Free Essay

About Unmanned Railway Crossing

In: Social Issues

Submitted By anup18kv
Words 8042
Pages 33
[pic]

✓ INTRODUCTION ✓ ALLOTROPHIC FORMS OF CARBONS ✓ APPLICATIONS

Carbon from Latin: carbo "coal" is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds. There are three naturally occurring isotopes, decaying with a half-life of about 5,730 years. Carbon is one of the few elements known since antiquity.
There are several allotropes of carbon of which the best known are graphite, diamond, and amorphous carbon. The physical properties of carbon vary widely with the allotropic form. For example, diamond is highly transparent, while graphite is opaque and black. Diamond is among the hardest materials known, while graphite is soft enough to form a streak on paper (hence its name, from the Greek word "to write"). Diamond has a very low electrical conductivity, while graphite is a very good conductor. Under normal conditions, diamond has the highest thermal conductivity of all known materials.
All carbon allotropes are solids under normal conditions with graphite being the most thermodynamically stable form. They are chemically resistant and require high temperature to react even with oxygen. The most common oxidation state of carbon in inorganic compounds is +4, while +2 is found in carbon monoxide and other transition metal carbonyl complexes. The largest sources of inorganic carbon are limestones, dolomites and carbon dioxide, but significant quantities occur in organic deposits of coal, peat, oil and methane clathrates. Carbon forms more compounds than any other element, with almost ten million pure organic compounds described to date, which in turn are a tiny fraction of such compounds that are theoretically possible under standard conditions.
Carbon is the 15th most abundant element in the Earth's crust, and the fourth most abundant element in the universe by mass after hydrogen, helium, and oxygen. It is present in all known life forms, and in the human body carbon is the second most abundant element by mass (about 18.5%) after oxygen This abundance, together with the unique diversity of organic compounds and their unusual polymer-forming ability at the temperatures commonly encountered on Earth, make this element the chemical basis of all known life.
Characteristics

The different forms or allotropes of carbon (see below) include the hardest naturally occurring substance, diamond, and also one of the softest known substances, graphite. Moreover, it has an affinity for bonding with other small atoms, including other carbon atoms, and is capable of forming multiple stable covalent bonds with such atoms. As a result, carbon is known to form almost ten million different compounds; the large majority of all chemical compounds. Carbon also has the highest sublimation point of all elements. At atmospheric pressure it has no melting point as its triple point is at 10.8 ± 0.2 MPa and 4,600 ± 300 K (~4,330 °C or 7,820 °F), so it sublimates at about 3,900 K
Carbon sublimes in a carbon arc which has a temperature of about 5,800 K (5,530 °C; 9,980 °F). Thus, irrespective of its allotropic form, carbon remains solid at higher temperatures than the highest melting point metals such as tungsten or rhenium. Although thermodynamically prone to oxidation, carbon resists oxidation more effectively than elements such as iron and copper that are weaker reducing agents at room temperature.
Carbon compounds form the basis of all known life on Earth, and the carbon-nitrogen cycle provides some of the energy produced by the Sun and other stars. Although it forms an extraordinary variety of compounds, most forms of carbon are comparatively unreactive under normal conditions. At standard temperature and pressure, it resists all but the strongest oxidizers. It does not react with sulfuric acid, hydrochloric acid, chlorine or any alkalis. At elevated temperatures carbon reacts with oxygen to form carbon oxides, and will reduce such metal oxides as iron oxide to the metal. This exothermic reaction is used in the iron and steel industry to control the carbon content of steel: Fe3O4 + 4 C(s) → 3 Fe(s) + 4 CO(g) with sulfur to form carbon disulfide and with steam in the coal-gas reaction: C(s) + H2O(g) → CO(g) + H2(g).
Carbon combines with some metals at high temperatures to form metallic carbides, such as the iron carbide cementite in steel, and tungsten carbide, widely used as an abrasive and for making hard tips for cutting tools.
As of 2009, graphene appears to be the strongest material ever tested. However, the process of separating it from graphite will require some technological development before it is economical enough to be used in industrial processes.

The system of carbon allotropes spans a range of extremes:
|Synthetic nanocrystalline diamond is the hardest material |Graphite is one of the softest materials known. |
|known.[19] | |
|Diamond is the ultimate abrasive. |Graphite is a very good lubricant, displaying |
| |superlubricity. |
|Diamond is an excellent electrical insulator. |Graphite is a conductor of electricity. |
|Diamond is the best known naturally occurring thermal |Some forms of graphite are used for thermal insulation |
|conductor |(i.e. firebreaks and heat shields) |
|Diamond is highly transparent. |Graphite is opaque. |
|Diamond crystallizes in the cubic system. |Graphite crystallizes in the hexagonal system. |
|Amorphous carbon is completely isotropic. |Carbon nanotubes are among the most anisotropic materials |
| |ever produced. |

Allotropy

[pic]

Allotropy or allotropism is the property of some chemical elements to exist in two or more different forms, known as allotropes of these elements. Allotropes are different structural modifications of an element;[1] the atoms of the element arebonded together in a different manner.
Take carbon for example: 4 common allotropes of carbon are diamond (where the carbon atoms are bonded together in a tetrahedral lattice arrangement), graphite(where the carbon atoms are bonded together in sheets of a hexagonal lattice),graphene (single sheets of graphite), and fullerenes (where the carbon atoms are bonded together in spherical, tubular, or ellipsoidal formations).
The term allotropy is used for elements only, not for compounds. The more general term, used for any crystalline material, is polymorphism. Allotropy refers only to different forms of an element within the same phase (i.e. different solid, liquid or gasforms); the changes of state between solid, liquid and gas in themselves are not considered allotropy.
For some elements, allotropes have different molecular formulae which can persist in different phases – for example, two allotropes of oxygen (dioxygen, O2 and ozone, O3), can both exist in the solid, liquid and gaseous states. Conversely, some elements do not maintain distinct allotropes in different phases – for examplephosphorus has numerous solid allotropes, which all revert to the same P4 form when melted to the liquid state.
History

The concept of allotropy was originally proposed in 1841 by the Swedish scientist Baron Jöns Jakob Berzelius (1779–1848) who offered no explanation.[2] The term is derived from the Greek (allotropia; variability, changeableness).[3] After the acceptance of Avogadro's hypothesis in 1860 it was understood that elements could exist as polyatomic molecules, and the two allotropes of oxygen were recognized as O2 and O3. In the early 20th century it was recognized that other cases such as carbon were due to differences in crystal structure.
By 1912, Ostwald noted that the allotropy of elements is just a special case of the phenomenon of polymorphism known for compounds, and proposed that the terms allotrope and allotropy be abandoned and replaced by polymorph and polymorphism. Although many other chemists have repeated this advice, IUPAC and most chemistry texts still favour the usage of allotrope and allotropy for elements only.

Allotropes

Atomic carbon is a very short-lived species and, therefore, carbon is stabilized in various multi-atomic structures with different molecular configurations called allotropes. The three relatively well-known allotropes of carbon are amorphous carbon, graphite, and diamond. Once considered exotic, fullerenes are nowadays commonly synthesized and used in research; they include buckyballs, carbon nanotubes, carbon nanobuds and nanofibers. Several other exotic allotropes have also been discovered, such as lonsdaleite, glassy carbon, carbon nanofoam and linear acetylenic carbon (carbyne).
The amorphous form is an assortment of carbon atoms in a non-crystalline,irregular, glassy state, which is essentially graphite but not held in a crystalline macrostructure. It is present as a powder, and is the main constituent of substances such as charcoal, lampblack (soot) and activated carbon. At normal pressures carbon takes the form of graphite, in which each atom is bonded trigonally to three others in a plane composed of fused hexagonal rings, just like those in aromatic hydrocarbons. The resulting network is 2-dimensional, and the resulting flat sheets are stacked and loosely bonded through weak van der Waals forces. This gives graphite its softness and its cleaving properties (the sheets slip easily past one another). Because of the delocalization of one of the outer electrons of each atom to form a π-cloud, graphite conducts electricity, but only in the plane of each covalently bonded sheet. This results in a lower bulk electrical conductivity for carbon than for most metals. The delocalization also accounts for the energetic stability of graphite over diamond at room temperature.
Some allotropes of carbon: a) diamond; b) graphite; c) lonsdaleite; d–f) fullerenes (C60, C540, C70); g) amorphous carbon; h) carbon nanotube.
At very high pressures carbon forms the more compact allotrope diamond, having nearly twice the density of graphite. Here, each atom is bonded tetrahedrally to four others, thus making a 3-dimensional network of puckered six-membered rings of atoms. Diamond has the same cubic structure as silicon and germanium and because of the strength of the carbon-carbon bonds, it is the hardest naturally occurring substance in terms of resistance to scratching. Contrary to the popular belief that "diamonds are forever", they are in fact thermodynamically unstable under normal conditions and transform into graphite. However, due to a high activation energy barrier, the transition into graphite is so extremely slow at room temperature as to be unnoticeable. Under some conditions, carbon crystallizes as lonsdaleite. This form has a hexagonal crystal lattice where all atoms are covalently bonded. Therefore, all properties of lonsdaleite are close to those of diamond.
Fullerenes have a graphite-like structure, but instead of purely hexagonalpacking, they also contain pentagons (or even heptagons) of carbon atoms, which bend the sheet into spheres, ellipses or cylinders. The properties of fullerenes (split into buckyballs, buckytubes and nanobuds) have not yet been fully analyzed and represent an intense area of research in nanomaterials. The names "fullerene" and "buckyball" are given after Richard Buckminster Fuller, popularizer of geodesic domes, which resemble the structure of fullerenes. The buckyballs are fairly large molecules formed completely of carbon bonded trigonally, forming spheroids (the best-known and simplest is the soccerball-shaped C60 buckminsterfullerene). Carbon nanotubes are structurally similar to buckyballs, except that each atom is bonded trigonally in a curved sheet that forms a hollow cylinder. Nanobuds were first reported in 2007 and are hybrid bucky tube/buckyball materials (buckyballs are covalently bonded to the outer wall of a nanotube) that combine the properties of both in a single structure.
Of the other discovered allotropes, carbon nanofoam is a ferromagnetic allotrope discovered in 1997. It consists of a low-density cluster-assembly of carbon atoms strung together in a loose three-dimensional web, in which the atoms are bonded trigonally in six- and seven-membered rings. It is among the lightest known solids, with a density of about 2 kg/m3. Similarly, glassy carbon contains a high proportion of closed porosity, but contrary to normal graphite, the graphitic layers are not stacked like pages in a book, but have a more random arrangement. Linear acetylenic carbon has the chemical structure -(C:::C)n-. Carbon in this modification is linear with sp orbital hybridization, and is a polymer with alternating single and triple bonds. This type of carbyne is of considerable interest to nanotechnology as its Young's modulus is forty times that of the hardest known material – diamond.
"Present day" (1990s) sea surface dissolved inorganic carbon concentration (from the GLODAP climatology)
Carbon is the fourth most abundant chemical element in the universe by mass after hydrogen, helium, and oxygen. Carbon is abundant in the Sun, stars, comets, and in the atmospheres of most planets. Some meteorites contain microscopic diamonds that were formed when the solar system was still a protoplanetary disk. Microscopic diamonds may also be formed by the intense pressure and high temperature at the sites of meteorite impacts.
In combination with oxygen in carbon dioxide, carbon is found in the Earth's atmosphere (approximately 810 gigatonnes of carbon) and dissolved in all water bodies (approximately 36,000 gigatonnes of carbon). Around 1,900 gigatonnes of carbon are present in the biosphere. Hydrocarbons (such as coal, petroleum, and natural gas) contain carbon as well—coal "reserves" (not "resources") amount to around 900 gigatonnes, and oil reserves around 150 gigatonnes. Proven sources of natural gas are about 175 trillion cubic metres (representing about 105 gigatonnes carbon), but it is estimated that there are also about 900 trillion cubic metres of "unconventional" gas such as shale gas, representing about 540 gigatonnes of carbon. Carbon is also locked up as methane and methane hydrates in polar regions. It is estimated that at least 1,400 Gt of carbon is in this form just in (and under) the submarine permafrost of the Siberian Shelf.
Carbon is a major component in very large masses of carbonate rock (limestone, dolomite, marble and so on). Coal is the largest commercial source of mineral carbon, accounting for 4,000 gigatonnes or 80% of fossil carbon fuel. It is also rich in carbon – for example, anthracite contains 92–98%.As for individual carbon allotropes, graphite is found in large quantities in the United States (mostly in New York and Texas), Russia, Mexico, Greenland, and India. Natural diamonds occur in the rock kimberlite, found in ancient volcanic "necks," or "pipes". Most diamond deposits are in Africa, notably in South Africa, Namibia, Botswana, the Republic of the Congo, and Sierra Leone. There are also deposits in Arkansas, Canada, the Russian Arctic, Brazil and in Northern and Western Australia. Diamonds are now also being recovered from the ocean floor off the Cape of Good Hope. However, though diamonds are found naturally, about 30% of all industrial diamonds used in the U.S. are now made synthetically.
Carbon-14 is formed in upper layers of the troposphere and the stratosphere, at altitudes of 9–15 km, by a reaction that is precipitated by cosmic rays. Thermal neutrons are produced that collide with the nuclei of nitrogen-14, forming carbon-14 and a proton.

[pic]

o COAL o DIAMOND o GRAPHITE o CHARCOAL

COAL

Coal is a combustible black or brownish-black sedimentary rock normally occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure. Coal is composed primarily of carbon along with variable quantities of other elements, chiefly hydrogen, with smaller quantities of sulfur, oxygen and nitrogen.
[pic]

Physical Properties:

The development of coking property is an intrinsic property. The reason for development of coking property has not yet been clearly established. By physical tests it can be determined whether the coal is coking or non-coking. The following destructive physical test is used for finding the coking propensity of coal.

1. Geisler Plastometer: Equipment should give a reading between 500 to 2000 dial divisions per minute. Higher the fluidity of coal mass, batter will be the dials division per minute.
2. Caking Index: In this test certain amount of powered coal is thoroughly mixed with graded and sized sand. The total quantity of sand and coal should not exceed 25 grams. This mixture when heated at 9250 in the absence of air, after cooling down should a coherent residue. This coherent residue should be able to withstand a weight of 500 grams without generating more than 5% of powder out of the residue. If the solid residue more than 5% then the proportion of coal in the mixture of sand and coal should be increased and vice versa. Normally caking index for coking coal should vary from 20-24 for bee-hive oven the minimum index should be 13 and maximum 24. 3. Swelling Index: During determination of volatile matter in coking coal a solid reside in left, comprising of fixed carbon and mineral matter. The solid residue that is the coke bead is viewed horizontally at the same level of the eye. It will be observed that the top surface of the bead has developed some amount of swelling. This swelling is compared with standard chart indicating There quantum of swelling and a number indicating swelling index. Swelling index varying between 2.-5 is ideal for coke manufacturing. The high swelling coal is not charged for coke making as it would create unnecessary pressure on the side wall of the oven will also produce a coke porous structure.
4. Volatile Matter: The volatile matter of coking coal should vary between 19-26% on DMMF basis. A coal with less VM then 19% will give rise to a coke which will not have proper physical property. A coal with VM higher than 26% will give rise to coke with more porosity and physical strength, such as CSR and CRI. The VM in coal consist of various gaseous products which has generated when the coal is heated in absence of air at temperature more than 900o C. The gases, consists of combination of carbon and hydro-aromatic compound. The gases mainly methane, Acetylene, gaseous Amino – compound. The gases mainly Mathane, Hydrogen and Carbon and some other hydrogen-aromatic compounds such as phenol and benzene. Some amount of tar in gaseous from is also generated.

5. Petrographic Analysis and Reflectance: Another most important nondestructive test of coal which is used for determining of coking coal is the petrographic analysis & reflectance. The coking coal should have a minimum of 60% virtrain (active constituents) and maximum of 40% Inertinite (nonreactive constituent). For finding out the physical strength of the coke, reflectance studies on coking coal are also done. In this study the ideal value of reflectance will be within 1.3 – 1.5. GenerallyC) Physical Properties: The development of coking property is an intrinsic property. The reason for development of coking property has not yet been clearly established. By physical tests it can be determined whether the coal is coking or non-coking. The following destructive physical test is used for finding the coking propensity of coal.

Chemical properties:

1.Carbon: The elements carbon expressed on dry mineral matter free (DMMF) basis should vary between 85-88%. · Hydrogen: The hydrogen DMMF basis should vary between 3.7 to 4.5%. 2. Sulpher: In the suplher both organic & inorganic should not exceed 0.75% on DMMF basis.
3. Phosphorous: The Phosphorous present in the coking coal should not exceed 0.15 – 0.25%.
4. Other elements: Such as Nitrogen, Iron & Other rarer elements must be present in traces.

Applications:

Coal Catalyst Applications
|Cormetech designs and manufactures catalysts unique to coal-fired applications that ensure long-life and highly effective catalyst|
|performance. We offer guarantees tailored to the individual client requirements. |
|High NOx Removal |
|Cormetech coal catalysts are ideal for a variety of flue gas properties, particulate characteristics and temperature ranges |
|accommodating both high and low dust applications for a range of coal types. Our catalyst composition minimizes deactivation |
|caused by poisons such as arsenic and calcium oxide deposits. Our integrated design of the SCR catalyst and its modular frame |
|maximizes NOx reduction and balance of plant operations. |
| | |
|Low SO2 Conversion |[pic] |
|SO3 mitigation is a growing need among coal-fired power plants. A challenge faced |Our low SO2 conversion catalyst achieves less |
|by several power plants is to lower SO2conversion, while maintaining high |than 0.1% SO2 oxidation while maintaining all |
|NOx reduction levels and low ammonia slip. In order to meet this need, we have |other key product performance features. |
|developed a breakthrough low SO2 conversion catalyst that utilizes our unique | |
|extrusion expertise, product and materials know-how and extensive field experience | |
|of catalyst technology. The low SO2conversion catalyst is optimized to reduce | |
|volume, pressure drop and SO2 oxidation. This low SO2 conversion is achieved due to| |
|advanced features such as: | |
|Greater open area | |
|Thinner catalyst walls | |
|Excellent material utilization | |
|Improved composition and geometry for catalyst strength | |
| | |
| | |

DIAMOND

The diamond industry can be broadly separated into two basically distinct categories: one dealing with gem-grade diamonds and another for industrial-grade diamonds. While a large trade in both types of diamonds exists, the two markets act in dramatically different ways.
A large trade in gem-grade diamonds exists. Unlike precious metals such as gold or platinum, gem diamonds do not trade as a commodity: there is a substantial mark-up in the sale of diamonds, and there is not a very active market for resale of diamonds.
The market for industrial-grade diamonds operates much differently from its gem-grade counterpart. Industrial diamonds are valued mostly for their hardness and heat conductivity, making many of the gemological characteristics of diamond, including clarity and color, mostly irrelevant. This helps explain why 80% of mined diamonds (equal to about 100 million carats or 20 tonnes annually), unsuitable for use as gemstones and known as bort, are destined for industrial use. In addition to mined diamonds, synthetic diamonds found industrial applications almost immediately after their invention in the 1950s; another 3 billion carats (600 tonnes) of synthetic diamond is produced annually for industrial use. The dominant industrial use of diamond is in cutting, drilling, grinding, and polishing. Most uses of diamonds in these technologies do not require large diamonds; in fact, most diamonds that are gem-quality except for their small size, can find an industrial use. Diamonds are embedded in drill tips or saw blades, or ground into a powder for use in grinding and polishing applications. Specialized applications include use in laboratories as containment for high pressure experiments high-performance bearings, and limited use in specialized windows. With the continuing advances being made in the production of synthetic diamonds, future applications are beginning to become feasible. Garnering much excitement is the possible use of diamond as a semiconductor suitable to build microchips from, or the use of diamond as a heat sink in electronics

[pic]

|PROPERTIES OF DIAMOND | |
| In diamond each C-atom utilizes its four unpaired electrons in bond formation. These bonding electrons are localized. Due |
|to this reason diamond is a bad conductor of electricity. |
| Diamond is the hardest substance ever known. |
| Pure diamond is cloudless. |
| Its melting point is 3500OC. |
| Pure diamond is transparent to x-rays. |
| It has high refractive index i.e. 2.45. |
| Due to impurities it may be colored. |
| Its density is 3.5 gm/cm3. |

PHYSICAL AND CHEMICAL PROPERTIES

1.Hardness and crystal structure
Known to the ancient Greeks as proper, unalterable, unbreakable and sometimes called adamant, diamond is the hardest known naturally occurring material, scoring 10 on the Mohs scale of mineral hardness. Diamond is extremely strong due to the structure of its carbon atoms, where each carbon atom has four neighbors joined to it with covalent bonds. The material boron nitride, when in a form structurally identical to diamond (zincblende structure), is nearly as hard as diamond; a currently hypothetical material, beta carbon nitride, may also be as hard or harder in one form. It has been shown that some diamond aggregates having nanometer grain size are harder and tougher than conventional large diamond crystals, thus they perform better as abrasive material. Due to the use of those new ultra-hard materials for diamond testing, more accurate values are now known for diamond hardness. A surface perpendicular to the crystallographic direction(that is the longest diagonal of a cube) of a pure (i.e. type IIa) diamond has a hardness value of 167 GPa when scratched with an nanodiamond tip, while the nanodiamond sample itself has a value of 310 GPa when tested with another nanodiamond tip. Because the test only works properly with a tip made of harder material than the sample being tested, the true value for nanodiamond is likely somewhat lower than 310 GPa.

2. Toughness
Unlike hardness, which only denotes resistance to scratching, diamond's toughness or tenacity is only fair to good. Toughness relates to the ability to resist breakage from falls or impacts. Due to diamond's perfect and easy cleavage, it is vulnerable to breakage. A diamond will shatter if hit with an ordinary hammer. The toughness of natural diamond has been measured as 2.0 MPa m1/2, which is good compared to other gemstones, but poor compared to most engineering materials. As with any material, the macroscopic geometry of a diamond contributes to its resistance to breakage. Diamond has a cleavage plane and is therefore more fragile in some orientations than others. Diamond cutters use this attribute to cleave some stones, prior to faceting.[9][10]
3. Color and its causes
Diamonds occur in various colors — black, brown, yellow, gray, white, blue, orange, purple to pink and red. Colored diamonds contain crystallographic defects, including substitutional impurities and structural defects, that cause the coloration. Theoretically, pure diamonds would be transparent and colorless. Diamonds are scientifically classed into two main types and several subtypes, according to the nature of defects present and how they affect light absorption:

4. Luster
The luster of a diamond is described as 'adamantine', which simply means diamond-like. Reflections on a properly cut diamond's facets are undistorted, due to their flatness. The refractive index of diamond (as measured via sodium light, 589.3 nm) is 2.417. Because it is cubic in structure, diamond is also isotropic. Its high dispersionof 0.044 (variation of refractive index across the visible spectrum) manifests in the perceptible fire of cut diamonds. This fire—flashes of prismatic colors seen in transparent stones—is perhaps diamond's most important optical property from a jewelry perspective. The prominence or amount of fire seen in a stone is heavily influenced by the choice of diamond cut and its associated proportions (particularly crown height), although the body color of fancy (i.e., unusual) diamonds may hide their fire to some degree.

5. Fluorescence
.Diamonds exhibit fluorescence, that is, they emit light of various colors and intensities under long-wave ultra-violet light (365 nm): Cape series stones (type Ia) usually fluoresce blue, and these stones may also phosphoresce yellow, a unique property among gemstones. Other possible long-wave fluorescence colors are green (usually in brown stones), yellow, mauve, or red (in type IIb diamonds). In natural diamonds, there is typically little if any response to short-wave ultraviolet, but the reverse is true of synthetic diamonds. Some natural type IIb diamonds phosphoresce blue after exposure to short-wave ultraviolet. In natural diamonds, fluorescence under X-rays is generally bluish-white, yellowish or greenish. Some diamonds, particularly Canadian diamonds, show no fluorescence.

GRAPHITE

Commercially viable natural deposits of graphite occur in many parts of the world, but the most important sources economically are in China, India, Brazil and North Korea. Graphite deposits are of metamorphic origin, found in association with quartz, mica and feldspars in schists, gneisses and metamorphosed sandstones and limestone as lenses or veins, sometimes of a meter or more in thickness. Deposits of graphite in Borrowdale, Cumberland, England were at first of sufficient size and purity that, until the 19th century, pencils were made simply by sawing blocks of natural graphite into strips before encasing the strips in wood. Today, smaller deposits of graphite are obtained by crushing the parent rock and floating the lighter graphite out on water.
There are three types of natural graphite—amorphous, flake or crystalline flake, and vein or lump. Amorphous graphite is the lowest quality and most abundant. Contrary to science, in industry "amorphous" refers to very small crystal size rather than complete lack of crystal structure. Amorphous is used for lower value graphite products and is the lowest priced graphite. Large amorphous graphite deposits are found in China, Europe, Mexico and the United States. Flake graphite is less common and of higher quality than amorphous; it occurs as separate plates that crystallized in metamorphic rock. Flake graphite can be four times the price of amorphous. Good quality flakes can be processed into expandable graphite for many uses, such as flame retardants. The foremost deposits are found in Austria, Brazil, Canada, China, Germany and Madagascar. Vein or lump graphite is the rarest, most valuable, and highest quality type of natural graphite. It occurs in veins along intrusive contacts in solid lumps, and it is only commercially mined in Sri Lanka.
According to the USGS, world production of natural graphite was 1.1 million tonnes in 2010, to which China contributed 800,00 t, India 130,000 t, Brazil 76,000 t, North Korea 30,000 t and Canada 25,000 t. No natural graphite was reported mined in the United States, but 118,000 t of synthetic graphite with an estimated value of $998 million was produced in 2009.

[pic]
Graphite (named by Abraham Gottlob Werner in 1789, from the Greek "to draw/write", for its use in pencils) is one of the most common allotropes of carbon. Unlike diamond, graphite is an electrical conductor. Thus, it can be used in, for instance, electrical arc lamp electrodes. Likewise, under standard conditions, graphite is the most stable form of carbon. Therefore, it is used in thermochemistry as the standard state for defining the heat of formation of carbon compounds.

PROPERTIES:
Physical Properties of Graphite

1. Graphite is greyish black crystalline substance.
2. It has a soft and greasy texture, but has a metallic luster.
3. The specific gravity of graphite is only 2.2 g cm-3.
4. Due to the presence of a free valence electron, it is a good conductor of electricity.
5. It is also one of the stable forms of carbon.
6. The structure of graphite has hexagonal rings arranged in layers.

Chemical Properties of Graphite

1. Graphite is inactive and inert to almost all chemicals.
2. It does not burn in air, even if heated to high temperature. But if heated in oxygen, it burns completely to form only carbon dioxide
[pic]
3. It also gets oxidised to carbon dioxide, when heated with concentrated sulphuric acid and potassium dichromate.

Uses of Graphite

1. Graphite is used in making the 'lead' of pencils.
2. It is used in the production of refractory crucibles, which can withstand very high temperature.
3. Graphite being a conductor of electricity finds application in making electrodes.
4. It is used in making polishes and paints.
5. Graphite is used as lubricant in machines, which have to be operated at high temperatures. All such machines cannot be lubricated with oils, grease, etc. as they vaporize immediately at the high temperature. As a lubricant it is used as dry powder or mixed with water or oil. When mixed with water, it is called 'aqua-dag' and when mixed with oil, it is called 'oil dag'.
6. It is used for making electrotypes for printing, in the following manner. Wax impressions are made and then a thin layer of graphite powder is applied. Copper is deposited on this thin layer. The layer of graphite is used to give the negative electrical connection for carrying out electrolysis to deposit copper on it . After coating the required thickness, the wax can be melted out by dipping it in hot water.
7. Graphite is extensively used in nuclear reactors, to absorb neutrons. This helps in moderating the nuclear reaction.

CHARCOAL

Charcoal is the dark grey residue consisting of carbon, and any remaining ash, obtained by removing water and other volatile constituents from animal and vegetationsubstances. Charcoal is usually produced by slow pyrolysis, the heating of wood or other substances in the absence of oxygen (see pyrolysis, char and biochar). It is usually an impure form of carbon as it contains ash; however, sugar charcoal is among the purest forms of carbon readily available, particularly if it is not made by heating but by dehydrating with sulphuric acid to minimise introducing new impurities, as impurities can be removed from the sugar in advance. The resulting soft, brittle, lightweight, black, porous material resembles coal.[1]

[pic]

Uses

Charcoal has been used since the earliest times for a range of purposes including art and medicine, but by far its most important use has been as a metallurgical fuel. Charcoal is the traditional fuel of a blacksmith's forge and other applications where an intense heat is wanted. Charcoal was also used historically as a source of carbon black by grinding it up. In this form charcoal was important to early chemists and was a constituent of formulas for mixtures such as gunpowder. Due to its high surface area charcoal can be used as a filter, as a catalyst or as an absorbent.

1. Metallurgical fuel

Charcoal burns at intense temperatures, up to 2700 degrees Celsius. By comparison the melting point of iron is approximately 1200 to 1550 degrees Celsius. Due to its porosity it is sensitive to the flow of air and the heat generated can be moderated by controlling the air flow to the fire. For this reason charcoal is an ideal fuel for a forge and is still widely used by blacksmiths. Charcoal is also an excellent reducing fuel for the production of iron and has been used that way since Roman times. In the 16th century England had to pass laws to prevent the country from becoming completely denuded of trees due to production of iron. In the 19th century charcoal was largely replaced by coke, baked coal, in steel making due to cost. Charcoal is far superior fuel to coke, however, because it burns hotter and has no sulfur. Until World War II charcoal was still being used in Sweden to make ultra high-quality steel.

2. Cooking fuel
Prior to the industrial revolution charcoal was occasionally used as a cooking fuel. Modern "charcoal briquettes", widely used for outdoor grilling and barbecues in backyards and on camping trips, imitate this use, but are not actually charcoal. They are usually compacted mixtures of coal or coke and various binders.

3. Industrial fuel
Historically, charcoal was used in great quantities for smelting iron in bloomeries and later blast furnaces and finery forges. This use was replaced by coke during the Industrial Revolution. For this purpose, charcoal in England was measured in dozens (or loads) consisting of 12 sacks or shems or seams, each of 8 bushels.

4. Automotive fuel
In times of scarce petroleum, automobiles and even buses have been converted to burn wood gas (a gas mixture consisting primarily of diluting atmospheric nitrogen, but also containing combustible gasses, mostlycarbon monoxide) released by burning charcoal or wood in a wood gas generator. In 1931 Tang Zhongming developed an automobile powered by charcoal, and these cars were popular in China until the 1950s. Inoccupied France during World War II, wood and wood charcoal production for such vehicles (called gazogènes) increased from pre-war figures of approximately fifty thousand tons a year to almost half a million tons in 1943.
5. Purification and filtration
[pic]

Activated charcoal readily adsorbs a wide range of organic compounds dissolved or suspended in gases and liquids. In certain industrial processes, such as the purification of sucrose from cane sugar, impurities cause an undesirable color, which can be removed with activated charcoal. It is also used to absorb odors and toxins in gases, such as air. Charcoal filters are also used in some types of gas masks. The medical use of activated charcoal is mainly the adsorption of poisons, especially in the case of suicide attempts in which the patient has ingested a large amount of a drug. Activated charcoal is available without a prescription, so it is used for a variety of health-related applications. For example, it is often used to reduce discomfort (and embarrassment) due to excessive gas in the digestive tract.[citation needed]
Animal charcoal or bone black is the carbonaceous residue obtained by the dry distillation of bones. It contains only about 10% carbon, the remainder being calcium andmagnesium phosphates (80%) and other inorganic material originally present in the bones. It is generally manufactured from the residues obtained in the glue and gelatinindustries. Its decolorizing power was applied in 1812 by Derosne to the clarification of the syrups obtained in sugar refining; but its use in this direction has now greatly diminished, owing to the introduction of more active and easily managed reagents. It is still used to some extent in laboratory practice. The decolorizing power is not permanent, becoming lost after using for some time; it may be revived, however, by washing and reheating. Wood charcoal also to some extent removes coloring material from solutions, but animal charcoal is generally more effective.
PHYSICAL AND CHEMICAL PROPERTIES
A gram of activated carbon can have a surface area in excess of 500 m2, with 1500 m2 being readily achievable.[3] Carbon aerogels, while more expensive, have even higher surface areas, and are used in special applications.
Under an electron microscope, the high surface-area structures of activated carbon are revealed. Individual particles are intensely convoluted and display various kinds of porosity; there may be many areas where flat surfaces of graphite-like material run parallel to each other, separated by only a few nanometers or so. Thesemicropores provide superb conditions for adsorption to occur, since adsorbing material can interact with many surfaces simultaneously. Tests of adsorption behaviour are usually done with nitrogen gas at 77 K under high vacuum, but in everyday terms activated carbon is perfectly capable of producing the equivalent, by adsorption from its environment, liquid water from steam at 100 °C and a pressure of 1/10,000 of an atmosphere.
James Dewar, the scientist after whom the Dewar (vacuum flask) is named, spent much time studying activated carbon and published a paper regarding its absorption capacity with regard to gases.[4] In this paper, he discovered that cooling the carbon to liquid nitrogen temperatures allowed it to absorb significant quantities of numerous air gases, among others, that could then be recollected by simply allowing the carbon to warm again and that coconut based carbon was superior for the effect. He uses oxygen as an example, wherein the activated carbon would typically absorb the atmospheric concentration (21%) under standard conditions, but release over 80% oxygen if the carbon was first cooled to low temperatures.
Physically, activated carbon binds materials by van der Waals force or London dispersion force.
Activated carbon does not bind well to certain chemicals, including alcohols, glycols, strong acids and bases, metals and most inorganics, such as lithium, sodium,iron, lead, arsenic, fluorine, and boric acid.
Activated carbon does adsorb iodine very well and in fact the iodine number, mg/g, (ASTM D28 Standard Method test) is used as an indication of total surface area.
Contrary to a claim repeated[citation needed] throughout the web, activated carbon does not adsorb ammonia.
Carbon monoxide is not well absorbed by activated carbon. This should be of particular concern to those using the material in filters for respirators, fume hoods or other gas control systems as the gas is undetectable to the human senses, toxic to metabolism and neurotoxic.
Substantial lists of the common industrial and agricultural gases absorbed by activated carbon can be found online.[5]
Activated carbon can be used as a substrate for the application of various chemicals to improve the adsorptive capacity for some inorganic (and problematic organic) compounds such as hydrogen sulfide (H2S), ammonia (NH3), formaldehyde (HCOH), radioisotopes iodine-131(131I) and mercury (Hg). This property is known as chemisorption.
1.Iodine number
Many carbons preferentially adsorb small molecules. Iodine number is the most fundamental parameter used to characterize activated carbon performance. It is a measure of activity level (higher number indicates higher degree of activation), often reported in mg/g (typical range 500–1200 mg/g). It is a measure of the micropore content of the activated carbon (0 to 20 Å, or up to 2 nm) by adsorption of iodine from solution. It is equivalent to surface area of carbon between 900 m²/g and 1100 m²/g. It is the standard measure for liquid phase applications.
Iodine number is defined as the milligrams of iodine adsorbed by one gram of carbon when the iodine concentration in the residual filtrate is 0.02 normal. Basically, iodine number is a measure of the iodine adsorbed in the pores and, as such, is an indication of the pore volume available in the activated carbon of interest. Typically, water treatment carbons have iodine numbers ranging from 600 to 1100. Frequently, this parameter is used to determine the degree of exhaustion of a carbon in use. However, this practice should be viewed with caution as chemical interactions with the adsorbate may affect the iodine uptake giving false results. Thus, the use of iodine number as a measure of the degree of exhaustion of a carbon bed can only be recommended if it has been shown to be free of chemical interactions with adsorbates and if an experimental correlation between iodine number and the degree of exhaustion has been determined for the particular application.
2. Molasses
Some carbons are more adept at adsorbing large molecules. Molasses number or molasses efficiency is a measure of the mesopore content of the activated carbon (greater than 20 Å, or larger than 2 nm) by adsorption of molasses from solution. A high molasses number indicates a high adsorption of big molecules (range 95–600). Caramel dp (decolorizing performance) is similar to molasses number. Molasses efficiency is reported as a percentage (range 40%–185%) and parallels molasses number (600 = 185%, 425 = 85%). The European molasses number (range 525–110) is inversely related to the North American molasses number.
Molasses Number is a measure of the degree of decolorization of a standard molasses solution that has been diluted and standardized against standardized activated carbon. Due to the size of color bodies, the molasses number represents the potential pore volume available for larger adsorbing species. As all of the pore volume may not be available for adsorption in a particular waste water application, and as some of the adsorbate may enter smaller pores, it is not a good measure of the worth of a particular activated carbon for a specific application. Frequently, this parameter is useful in evaluating a series of active carbons for their rates of adsorption. Given two active carbons with similar pore volumes for adsorption, the one having the higher molasses number will usually have larger feeder pores resulting in more efficient transfer of adsorbate into the adsorption space.
3. Tannin
Tannins are a mixture of large and medium size molecules. Carbons with a combination of macropores and mesopores adsorb tannins. The ability of a carbon to adsorb tannins is reported in parts per million concentration (range 200 ppm–362 ppm).
4. Methylene blue
Some carbons have a mesopore (20 Å to 50 Å, or 2 to 5 nm) structure which adsorbs medium size molecules, such as the dye methylene blue. Methylene blue adsorption is reported in g/100g (range 11–28 g/100g).
5. Dechlorination
Some carbons are evaluated based on the dechlorination half-value length, which measures the chlorine-removal efficiency of activated carbon. The dechlorination half-value length is the depth of carbon required to reduce the chlorine level of a flowing stream from 5 ppm to 3.5 ppm. A lower half-value length indicates superior performance.
6. Apparent density
Higher density provides greater volume activity and normally indicates better quality activated carbon.
7. Hardness/abrasion number
It is a measure of the activated carbon’s resistance to attrition. It is important indicator of activated carbon to maintain its physical integrity and withstand frictional forces imposed by backwashing, etc. There are large differences in the hardness of activated carbons, depending on the raw material and activity level.
8. Ash content
It reduces the overall activity of activated carbon. It reduces the efficiency of reactivation. The metal oxides (Fe2O3) can leach out of activated carbon resulting in discoloration. Acid/water soluble ash content is more significant than total ash content. Soluble ash content can be very important for aquarists, as ferric oxide can promote algal growths. A carbon with a low soluble ash content should be used for marine, freshwater fish and reef tanks to avoid heavy metal poisoning and excess plant/algal growth.
9. Carbon tetrachloride activity
Measurement of the porosity of an activated carbon by the adsorption of saturated carbon tetrachloride vapour.
10. Particle size distribution
The finer the particle size of an activated carbon, the better the access to the surface area and the faster the rate of adsorption kinetics. In vapour phase systems this needs to be considered against pressure drop, which will affect energy cost. Careful consideration of particle size distribution can provide significant operating benefits.

[pic]

CARBON
Carbon is an indipensable element in industry. By far, the greatest single use of carbon is in the form of coke for the iron and steel industry. The major portion of this coke is used in the reduction of iron ore in blast furnaces.As in the rubber industry, the major applications for carbon blacks are in the printing ink, paint, paper and plastic industries. Minor amounts are used in the manufacture of dry cells and carbon brushes, and as insulation.The largest single application for gas phase activated carbons is in the recovery of volatile organic solvents from air or vapor mixtures. Another large application is in the purification and separation of natural and industrial gases.Main applications for pyrographite and the fiber forms of manufactured graphite are found as components for rockets, missile and other aerospace vehicles.

DIAMOND
Diamond is the only precious stone composed of a single element. Though diamonds have been discovered on all the major continents, over 90% of the world's natural diamond production comes from Africa. Other significant producers are Russia (mainly Siberia), China, Brazil and Angola. In the United States, diamonds can be found in the states of Arkansas, Virginia, Wisconsin and California. India, that was the only producer before the XVIII century, has a very small production nowadays. Diamond crystals can also be found in meteorites.In spite of the first attempt of the Scottish chemist J. Balentine Hannay, in 1880, to produce artificial diamond it was not until 1955 that the General Electric Company first announced the successful development of a reproducible process. The work of Francis Bundy, Tracy Hall, Herbert M. Strong and Robert H. Wentorf complemented the research by Percy W. Bridgman from the University of Harvard. This diamonds have industrial quality being nowadays produced by an identical method, in large scale. Precious-stone quality crystals were obtained in 1970 by Strong and Wentorf in a process involving extremely high pressures and temperatures.In spite of the popular interest on diamonds based on its value as gems, it is on the industrial domain that diamonds play a major role. They can be used in cutting or in turnery and to pierce alumina, quartz, glass and ceramics. Diamond powder is used to polish steel and alloys.

Graphite
Graphite crystals consist of superposed layers of carbon atoms, in an infinite net of hexagonal cycles. The free space between the layers can be occupied by several distint atoms, molecules or ions (oxygen, nitrogen, halogen, alkaly metals etc.), thus producing lamellar compounds.In normal conditions of pressure, the graphite layers easily glide due to the very weak bounds with the vicinity (van der Waals bonding); this is the reason why graphite is used as a lubricant.Graphite occurs mainly in Corea, Austria, Russia, China, Mexico, Madagascar, Germany, Sri Lanka and Norway. However, most of the graphite used nowadays has a synthetic origin.Thanks to its infusibility, hardness and conducting power, this substance is mainly used in the production of refractory coatings and crucibles in the foundry industry. It is also used in the production of pencils, electrodes for multiples purposes, rotary brushes, lubricants corrosion-resistent paints.

Similar Documents

Premium Essay

Crossing - Essay

...Essay- Crossing The short story ”Crossing” by Mark Slouka, written in 2009 is about a father and his son who is on a trip. The title of the short story is "Crossing" And this title is up to what the story is about. My interpretation of this story is that the message is to rebuild trust in relationships can be difficult. The main character tries so hard to rebuild his relationship with his son by making him trust him when the cross the river. Because it could happen that he slips on the rocks in the river, so actually the son let his life depends on a trust to his father. The main character is a man who has a young son and he were married once. The text does not tell us directly that he is divorced but there are things that leads up to the fact that he was for example, it says on page 1 line 15 “For a long time he hadn't wanted her back”. This tells us that he is separated from a woman but not that they are divorced. Another example could be when he looks at the yard page 1 line 14 “the azaleas he'd planted” This tells us that he once had lived there and planted an azaleas. Based on these facts about the man I would guess that he is around his thirties. The main character has hope for getting his son’s trust back and therefore he arranges a trip to an old barn across the river. The main character is the one who has destroyed the relationship with his wife because on page 4 line 135 is says, “My God, All his other fuckups were just preparations for this.” The main character......

Words: 938 - Pages: 4

Free Essay

Railway

...1 HIGHLIGHTS OF THE RAILWAY BUDGET 2014-15 Thrust 1. Safety 2. Project Delivery 3. Passenger Amenities/Services with focus on food services & on cleanliness, sanitation, toilets 4. Financial Discipline 5. Resource Mobilization 6. IT Initiatives 7. Transparency & System Improvements. Major Challenges facing the Railway System _ Vast tracts of hinterland waiting for rail connectivity. _ Railways expected to earn like a commercial enterprise but serve like a welfare organization. _ Railways carry Social Service Obligation of more than Rs 20,000 cr by carrying services below cost. This is nearly 16.6% of GTR and is almost half of Railways’ Plan Outlay under budgetary sources. _ Surplus revenues declining; Hardly any adequate resources for its development works. _ Tariff policy adopted lacked rational approach; passenger fares kept lower than costs; loss per passenger kilometer increased from 10 Paise per Km in 2000-01 to 23 Paise in 2012-13. _ ‘Decade of Golden Dilemma’ – choosing between commercial and social viability. _ Share of Railways in freight traffic coming down consistently. _ Rs 5 lakh crore required for ongoing projects alone. _ Focus so far in sanctioning more and more projects with inadequate prioritization rather than completing them; Of the 674 projects worth Rs 1,57,883 cr sanctioned in the last 30 years, only 317 could be completed. Completing the balance requires Rs 1,82,000 cr. _ Most of Gross Traffic Receipts is spent on......

Words: 2416 - Pages: 10

Premium Essay

The Crossing

...care required to cross it. The details are not particularly subtle. For instance, the father remembers when he was a boy crossing the river with his own father and asking, “what do you do if you fall?” His father answered, “Don’t fuckin’ fall.” It becomes clear where this story is headed. Yet we forget this inevitable end because of the second thing Slouka does. While the river takes a central place in the story, the focus is actually on the father’s memories and thoughts. In fact, the river doesn’t even appear until the fifth paragraph. The story opens in the house of the man’s ex-wife, where the man is picking up his son: “He went inside, wiping his shoes and ducking his head like a visitor, and when the boy came running into the living room he threw him over his shoulder, careful not to hit his head on the corner of the TV, and at some point he saw her watching them, leaning against the kitchen counter in her bathrobe, and when he looked at her she shook her head and looked away and at that moment he thought, maybe—maybe he could make this right.” Slouka uses this opening to set the stakes: the man is going to use this camping trip to make things right with his family. His thoughts circle this idea throughout the story, even as he’s crossing the river. And so he does not see a second set of story stakes appear. While the story starts out being about making this right with his family, it will end with both two lives in the balance....

Words: 330 - Pages: 2

Premium Essay

The Crossing

...Crossing Mark Slouka wrote the short story “Crossing” in 2009. This short brings us through a dangerous situation about a farther and son trying to cross a wild river. It is a great trip for a farther to spend some quality time with his son out in the wild nature and to bond with each other. It is very typical for an American family, to have such values about a “farther and son relationship”. The farther in this story takes his son to a place where he went with his own farther, when he was young. This brings me to the theme of the story, which could be “disappointment” or “failure”. It is mentioned that farther has made many “fuckups” and he does not want this experience with his son to become one of those fuckups. At the beginning of the short story, we are introduced to the farther, and the difficult period of his life that he is in. The farther reminds himself of his childhood, when he was seventeen years old and went with his farther on a trip into the wild. He gets very disappointed when he returns with his son and realizes that the barn and all the other things in the forest are barely recognizable. He has probably had a bad relationship with his own farther, and does not wish the same for him and his own son. He also thinks back on some of the bad things about his own farther, especially the way he spoke to him as a child “Don’t fucking fall” (p.2, l. 63). The farther is also divorced from the son’s mother he looks at “…the azaleas he’d planted…” (p.1, l.14) and......

Words: 706 - Pages: 3

Premium Essay

The Crossing

...The crossing The relationship between the father and the son The protagonist is an unnamed man somewhere between 30-50 years old, and located in a small depression, because text says; "He had not been happy in a while." The protagonist is divorced or separated from his wife: "... He had not wanted here back, had not wanted much of anything really" (line.15) It would seem that the protagonist himself is to blame for the divorce, as he nurtures a desire that things should work again, both in relation to his ex-wife, but perhaps most in relation to his son. The father is very caring and loving to his son, and you quickly sympathize with him as the reader "... when the boy came running into the living room he threw him over his shoulder, careful not to hit his head on the corner of the TV…" (Page 2. line16-17) The protagonist wants to pass some of the good childhood memories that he had with his own father. They also used to take the same trip, and the main character repeats many of the same principles and rituals with his own son. Since the reader does not have access to the boy's thoughts and feelings, just as we have in the father. The author paints a picture of him with descriptions and through his father's thoughts about him. Most of all, we get a picture of a small frail boy. This narrative technique enables the reader to quickly sympathize for the boy and especially his father, who tried to get him safely through their journey in the wilderness: "He looked at......

Words: 699 - Pages: 3

Premium Essay

Crossing

...Crossing The main character in the short story is a man in the middle of the thirties or around the age where he has a young son and has been married. When we read we get a feeling that he is divorced even when it is not written directly in the text, but as he sits in the driveway of a house and says: “the azaleas he’d planted” it gives us the impression that he is divorced. It also indicates that the main character has been living in the house with the mother to the son and now he has come to the house to pick up his son and he wants to make thinks right between himself and his wife again. All of this is described in the sentence: “He went inside, wiping his shoes and ducking his head like a visitor” and “and that moment he thought, maybe – maybe he could make things right”. That could be why he is taking their son on a trip; to take a small step and make up for some of his mistakes he has made. We only hear about the narrators’ thoughts and not about the sons: “He could hear himself breathing hard”. This make the narrator restricted and therefore we are only seeing the story from the man’s point of view. It also guides the reader through the story even though it is not told by a first person narrator but by a third person narrator. The narrative mode is describing through the story, the narrator gives small hints saying that something dangerous is about to happen. However, if nothing happens at first, the effect of the hints makes the reader anxious together with the......

Words: 884 - Pages: 4

Premium Essay

Crossing

...Crossing is a short story, which is written by Mark Slouka in 2009. The short story takes up father and son relationship. The father takes his son out on a trip to pass on their knowledge about how to conquer Mother Nature. But more important on that trip is, that it binds the father and the son together, and that is exactly what the father wishes to obtain. Through a third person narrator, the reader is presented to a father and his son. The father is pretending in the short story as a father who has a hard time in life after a divorce from his wife. Because of the divorce the father is now determined to find something that matters, and he wants a strong and sound relationship to his son, I don’t think the father have anything else in his life since the wife divorced him, and therefore he wants a good relationship with his son, so he wont lose him as well. It seems like it was the mother who wants the divorce, and it seems like the father has done something wrong which not could be forgiven “When he looked at her she shook her head and looked away and at that moment he thought, maybe – maybe he could make this right” and in that moment the father gets this idea that the son and him can bond trough male things, he wants to do things that the boy cannot do with his mother, by choosing something he did with his own father. Sometimes we gets glimpse of the things the father is struggled with, “He hadn’t been happy in a while”, that quote tells us that the father has lost the...

Words: 799 - Pages: 4

Premium Essay

Crossing

...Crossing Old traditions never die. Over thousands of years have fathers and sons taking on fishing trips. It is something very classic traditions to do. It creates a closer relationship between father and son. The shot story ”Crossing” is written by Mark Slouka in 2009. The title is crossing. The obvious reason why the title is crossing is because the father and his son have to cross a river. But usually is there always something deeper behind. Crossing can also mean to cross something in your life. You have to cross through hard times in your life. After I have read the story do I think the title crossing, can relate to the death. You are crossing from the earth and into the heaven. The short story is about a father and his son that try to cross a river. The father takes his own son to exactly the same place that he went with his own father back in the days. In the beginning of this story are we introduced with the father and his very difficult period of his life. He always reminds himself about his own childhood. When he was about 17 years old, took his father and him on a trip. He had a bad relationship with his father. His father often speaks hard to him and use swearword when he talk to his son. I think because he had a bad relationship to his own father and he has felt it first-hand. In the text: ““ It didn’t matter. Whatever it was had passed. He and his son would be friends. Nothing mattered more.” That shows us that he only want to be a better......

Words: 861 - Pages: 4

Premium Essay

Railways

...Indian Railways and IT Systems Used 1. ERP- enterprise resource planning (ERP)  IT enables signaling system MIS and LRDSS(Long Range Decision Support System) for investment optimization FOIS - Freight Operations Information System Comprehensive Payroll Processing System Vigilance software system Material Management Information System for P-way Comprehensive Accounting & Transaction System 2. CRM/PRS Online Ticket Booking Online Train Status Cell/Landline Rail Reservation Unreserved Ticketing System E-Payment of Freight 3. CONCERT Country Wide Network of Computerized Enhanced Reservation and Ticketing Integrates five Regional Reservation Centers into National PRS Grid Performs reservations for over 8.82 Lakh seats &Berths daily ( Peak rush -10.16 lakh) More than 4250 reservation terminals at more than 1200 locations Judicious mix local autonomy with uniformity of business rules. Very complex Business transactions - Handles Reservations, Modifications, Cancellations/ Refunds Comprehensive functionality 4. FOIS Freight Operations Information System An on line real time system for management and control of freight traffic Instant access to information regarding status of consignments in transit, for just in time inventory Assists in Asset Tracking, Asset Planning Performance Monitoring , to optimize Asset utilization Functions Using HR – Payroll GRP/Security – Vigilance Freight......

Words: 1945 - Pages: 8

Premium Essay

Crossing

...Crossing The shot story ”Crossing” is written by Mark Slouka in 2009. The short story brings us through a dangerous situation about a father and son trying to cross a wild river. It is a great trip for a father to spend some quality time with his son out in the wild nature and to bond with each other. It is very typical for an American family, to have such values about a “father and son relationship”. The father in this story takes his son to a place where he went with his own father, when he was young. This brings me to the theme of the story, which could be “disappointment” or “failure”. It is mentioned that the father has done a lot of “fuckups” and he does not want this experience with his son to become one of those fuckups. At the beginning of the short story we are introduced to the father, and the difficult period of his life that he is in. The father reminds himself of his own childhood, when he was seventeen years old and went with his father on a trip into the wild. He gets very disappointed when he returns with his son and realizes that the barn and all the other things in the forest are barely recognizable. He might have had a bad relationship with his own father and does not want the same relationship with his own son. He also remembers some of the bad things about his own father, especially the way he spoke to him as a child, when the father yelled “Don’t fucking fall” (p.2, l. 63). The father could also be divorced from the mother of his son, where he is......

Words: 735 - Pages: 3

Premium Essay

Crossing

...hints to the reader about a certain danger which lies in the future of the story making the reader feel a bit anxious along with the father. For example when they are crossing the river second time around. Just as the open ending of the short story, many things stand unsaid forcing the reader to reflect on the presented problems and themes. The setting of Crossing takes place in a nature reserve. The surroundings are very important for the story since it is carefully described along with the flashbacks and thoughts of the main character and his experiences. The setting helps providing an atmosphere throughout the story; for example, when a parachute like mist is described as seemingly dragging behind a car, provoking a flashback to past adventures for the main character, creating the effect of a foggy memory returning. “(...)Dragging a long cloud of mist like a parachute, and when it passed he touched the wipers to clear things up and his mind flashed to a scene of black road (…)” (line 1-2). The setting also insinuates the mood throughout the story. The barn they are hiking to is an old barn which the main character used to visit with his own father, it is described as being rather dilapidated “standing against the trees like a rib cage” (line 72), yet he associates the barn with good memories, making it a safe haven and a shelter from reality. “but there was something about pitching a tent inside the skeleton that was pretty neat(…) Something about rooms in rooms”......

Words: 579 - Pages: 3

Premium Essay

Automatic Railway Gate Control

...Software Requirements Specification FOR AUTOMATIC RAILWAY GATE CONTROL SYSTEM PREPARED BY: SHIKHAR MALIK (13BCE0494) EMAIL: shikhar.malik2013@vit.ac.in SUBMITTED TO: PROF. AKILA VICTOR SOFTWARE ENGINEERING LAB (L5+L6) SCHOOL OF COMPUTER SCIENCE AND ENGINEERING Table of contents 1. Introduction 1.1 Abstract……………………………………………………………………………………………………………………………..3 1.2 Purpose……………………………………………………………………………………………………………………………..4 1.3 Scope………………………………………………………………………….……………………………………………………..5 1.4 Overview ……………………………………………………………………………………………………………………….... 7 2. Overall Description 2.1 Process Model……………………………………………………………………………………………………………………8 2.2 Work Break-down Structure……………………………………………………………………………………………….9 2.3 Data flow Diagram……………………………………………………………………………………………………………. 10 2.4 Tentative Schedule…………………………………………………………………………………………………………….11 2.5 Use-Case Model ………………………………………………………………………………………………………………..12 3. Specific Requirement 3.1 Functional Requirements……………………………………………………………………………………………….....14 3.2 Non-Functional......

Words: 1517 - Pages: 7

Free Essay

Fpga Based Automatic Railway Gate Control Sysytem

...Aim of this project is control the unmanned rail gate automatically using FPGA platform. Today often we see news papers very often about the railway accidents happening at un- attended railway gates. Present project is designed to avoid such accidents if implemented in spirit. This project utilizes two powerful IR transmitter and two receivers,one pair of transmitter and receiver is fixed at upside (from the train comes) at a levelhigher than human being in exact alignment and similarly other pair is fixed at 1Km away from gate to detect train depature.IR sensor activation time is so adjusted by calculating the time taken at a certain speed to cross at least one compartment of standard minimum size of theIndian railway, normally 5 seconds. The sensors are fixed at 5000 meters on foreside and 1000 meters on aft side, wecall fore side sensor pair for common towards gate train, and aft side sensors for the train just Crosses the gate. When train cross the fore side sensor it gives signal to the gate receiver to close the gate. The buzzer is activated to clear the gate area for drivers .Gate motor is turned on in one direction and gate is closed, and stay closed till train crosses the gate and reaches aft side sensors when aft side receiver get activated motor turns in opposite direction and gate opens and motor stops . If there is any problem in the gate means it will operate red signal on both side for the driver indication. Train arrival and......

Words: 2028 - Pages: 9

Premium Essay

Organization Behavior of Bangladesh Railway

...of Dhaka. Submission Date: 16th May 2011. Assignment topic A Research on Bangladesh Railway [pic] □ Introduction: Roads & Railways Division is one of the important Divisions in the Government under the Ministry of Communication. Ministry of Communication comprises two Divisions, 1. Roads & Railways Division and 2. Bridges Division. Roads & Railways Division shoulders a vast task and plays a vital role in socio-economic development of our country. It governs the Departments/Organizations which are playing very important roles in building our new nation. These are : (1) Roads & Highways Department (RHD), (2) Bangladesh Railway, (3) Bangladesh Road Transport Authority (BRTA), (4) Bangladesh Road Transport corporation (BRTC), (5) Dhaka Transport Co-ordination Board and (6) The office of the Government Inspector of Bangladesh Railways (GIBR). The principal motto of this Division is to ensure improvement of socio-economic condition of the people of our country through formulating policies regarding roads, road transports and railways and through construction, development, expansion and maintenance of environment-friendly and user-friendly integrated roads and railway transportation. Bangladesh Railway (BR) is the state-owned rail transport agency of Bangladesh. It operates and maintains the entire railway network of the country. Railway operation in today's Bangladesh began on November 15, 1862 when 53.11 kilometers of 5 ft 6 in (1,676 mm)......

Words: 2640 - Pages: 11

Free Essay

Indian Railways

... and Railways play a key role in not only meeting the transport needs of the country, but also in binding together dispersed areas and promoting national integration. Indian Railways have emerged as the sinews of the Indian economy, and have reached out to bring together the great Indian family. Indian railway is a Central Government owned Railway Company of India, which owns and operates most of the country’s rail transport. Indian Railways has more than 64,215 kms of the track and 7,083 stations. It has the World’s fourth world’s largest network after those of the US, Russia and China. It carries 30 million passengers & .2.8 million tons of freight daily. Indian Railways, therefore, rightly occupy pride of place in the growth and development of the nation. Apart from normal trains connecting almost all part of the country, the Indian Railways also runs special luxury trains like the Palace on Wheels, Rajdhani Express, Shatabdi Express, Fairy Queen, etc. STATEMENT OF PROBLEM Railways play a crucial role in the modern economy. This project is done to identify and analyze the level of satisfaction of the consumers and their problems faced in the railways. It is one among the high preferable means of transport by the people of India. But there are various problems faced by them in different aspects in journey. OBJECTIVES  To know the consumers awareness about the services provided by the railways.  To study the consumer preferences towards......

Words: 5749 - Pages: 23