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- ALPHABETIC INDEX TO THE COMMODITIES SPECIFIED IN THE REVISED INDIAN TRADE CLASSIFICATION. Code No.
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ALPHABETIC INDEX TO THE COMMODITIES SPECIFIED IN THE REVISED INDIAN TRADE CLASSIFICATION. Code No.
From Wikipedia, the free encyclopedia Jump to navigation Jump to search Material consisting of numerous extremely fine fibers of glassFor the common composite material reinforced with glass fibers, see Fiberglass.
For the glass fiber used to transmit information, see Optical fiber. Bundle of glass fibersGlass fiber or glass fibre is a material consisting of numerous extremely fine fibers of glass. Glassmakers throughout history have experimented with glass fibers, but mass manufacture of glass fiber was only made possible with the invention of finer machine tooling.
In , Edward Drummond Libbey exhibited a dress at the World's Columbian Exposition incorporating glass fibers with the diameter and texture of silk fibers. Glass fibers can also occur naturally, as Pele's hair.
Glass wool, which is one product called 'fiberglass' today, was invented in — by Russell Games Slayter of Owens-Corning, as a material to be used as thermal building insulation. Glass fiber when used as a thermal insulating material, is specially manufactured with a bonding agent to trap many small air cells, resulting in the characteristically air-filled low-density 'glass wool' family of products.
Glass fiber has roughly comparable mechanical properties to other fibers such as polymers and carbon fiber. Although not as rigid as carbon fiber, it is much cheaper and significantly less brittle when used in composites.
Glass fibers are therefore used as a reinforcing agent for many polymer products; to form a very strong and relatively lightweight fiber-reinforced polymer FRP composite material called glass-reinforced plastic GRP , also popularly known as 'fiberglass'. This material contains little or no air or gas, is more dense, and is a much poorer thermal insulator than is glass wool. Contents1 Fiber formation2 Chemistry3 Properties3.
The technique of heating and drawing glass into fine fibers has been known for millennia; however, the use of these fibers for textile applications is more recent. Until this time, all glass fiber had been manufactured as staple that is, clusters of short lengths of fiber.
Toledo, Ohio. He first applied for a patent for a new process to make glass wool in The first commercial production of glass fiber was in When the two companies joined to produce and promote glass fiber, they introduced continuous filament glass fibers. In order to lower the necessary work temperature, other materials are introduced as 'fluxing agents' i. Ordinary A-glass 'A' for 'alkali-lime' or soda lime glass, crushed and ready to be remelted, as so-called cullet glass, was the first type of glass used for fiberglass.
E-glass 'E' because of initial electrical application , is alkali free, and was the first glass formulation used for continuous filament formation. It now makes up most of the fiberglass production in the world, and also is the single largest consumer of boron minerals globally.
It is susceptible to chloride ion attack and is a poor choice for marine applications. S-glass 'S' for 'Strength' is used when high tensile strength modulus is important, and is thus important in composites for building and aircraft construction. The same substance is known as R-glass 'R' for 'reinforcement' in Europe. C-glass 'C' for 'chemical resistance' and T-glass 'T' is for 'thermal insulator' — a North American variant of C-glass are resistant to chemical attack; both are often found in insulation-grades of blown fiberglass.
In its pure form it exists as a polymer, SiO2 n. If the glass is extruded and cooled quickly at this temperature, it will be unable to form an ordered structure. These atoms then form a network bonded at the corners by sharing the oxygen atoms.
The vitreous and crystalline states of silica glass and quartz have similar energy levels on a molecular basis, also implying that the glassy form is extremely stable. It is usual to introduce impurities into the glass in the form of other materials to lower its working temperature.
These materials also impart various other properties to the glass that may be beneficial in different applications. The first type of glass used for fiber was soda lime glass or A-glass 'A' for the alkali it contains. It is not very resistant to alkali. A newer, alkali-free  C-glass was developed to resist attack from chemicals, mostly acids that destroy E-glass. AR-glass is alkali-resistant glass. Most glass fibers have limited solubility in water but are very dependent on pH.
Chloride ions will also attack and dissolve E-glass surfaces. E-glass does not actually melt, but softens instead, the softening point being 'the temperature at which a 0. However, the increased surface area makes them much more susceptible to chemical attack. By trapping air within them, blocks of glass fiber make good thermal insulation, with a thermal conductivity of the order of 0. The freshest, thinnest fibers are the strongest because the thinner fibers are more ductile.
The more the surface is scratched, the less the resulting tenacity. Moisture is easily adsorbed and can worsen microscopic cracks and surface defects, and lessen tenacity. In contrast to carbon fiber, glass can undergo more elongation before it breaks. During drawing, the process where the hot glass is pulled to reduce the diameter of the fiber, the viscosity must be relatively low. If it is too high, the fiber will break during drawing.
However, if it is too low, the glass will form droplets instead of being drawn out into a fiber. Manufacturing processesMeltingThere are two main types of glass fiber manufacture and two main types of glass fiber product. First, fiber is made either from a direct melt process or a marble remelt process.
Both start with the raw materials in solid form. The materials are mixed together and melted in a furnace. Then, for the marble process, the molten material is sheared and rolled into marbles which are cooled and packaged. The marbles are taken to the fiber manufacturing facility where they are inserted into a can and remelted.
The molten glass is extruded to the bushing to be formed into fiber. In the direct melt process, the molten glass in the furnace goes directly to the bushing for formation.
This is a small metal furnace containing nozzles for the fiber to be formed through. It is almost always made of platinum alloyed with rhodium for durability. Platinum is used because the glass melt has a natural affinity for wetting it. Also, due to its cost and the tendency to wear, the platinum was alloyed with rhodium. In the direct melt process, the bushing serves as a collector for the molten glass. It is heated slightly to keep the glass at the correct temperature for fiber formation.
In the marble melt process, the bushing acts more like a furnace as it melts more of the material. The nozzle design is also critical. The number of nozzles ranges from to in multiples of The important part of the nozzle in continuous filament manufacture is the thickness of its walls in the exit region.
It was found that inserting a counterbore here reduced wetting. Today, the nozzles are designed to have a minimum thickness at the exit. As glass flows through the nozzle, it forms a drop which is suspended from the end. As it falls, it leaves a thread attached by the meniscus to the nozzle as long as the viscosity is in the correct range for fiber formation. The smaller the annular ring of the nozzle and the thinner the wall at exit, the faster the drop will form and fall away, and the lower its tendency to wet the vertical part of the nozzle.
Although slowing this speed down can make coarser fiber, it is uneconomic to run at speeds for which the nozzles were not designed. This size helps protect the fiber as it is wound onto a bobbin. The particular size applied relates to end-use. While some sizes are processing aids, others make the fiber have an affinity for a certain resin, if the fiber is to be used in a composite.
The glass can be blown or blasted with heat or steam after exiting the formation machine. Usually these fibers are made into some sort of mat. The most common process used is the rotary process. Here, the glass enters a rotating spinner, and due to centrifugal force is thrown out horizontally.
The air jets push it down vertically, and binder is applied. Then the mat is vacuumed to a screen and the binder is cured in the oven. However, the safety of glass fiber is also being called into question, as research shows that the composition of this material asbestos and glass fiber are both silicate fibers can cause similar toxicity as asbestos.
The American Conference of Governmental Industrial Hygienists, on the other hand, says that there is insufficient evidence, and that glass fiber is in group A4: 'Not classifiable as a human carcinogen'. Although both glass fiber and asbestos are made from silica filaments, NAIMA claims that asbestos is more dangerous because of its crystalline structure, which causes it to cleave into smaller, more dangerous pieces, citing the U. Department of Health and Human Services:Synthetic vitreous fibers [fiber glass] differ from asbestos in two ways that may provide at least partial explanations for their lower toxicity.
Because most synthetic vitreous fibers are not crystalline like asbestos, they do not split longitudinally to form thinner fibers. They also generally have markedly less biopersistence in biological tissues than asbestos fibers because they can undergo dissolution and transverse breakage. Fibers that persisted longer were found to be more carcinogenic. Like graphite-reinforced plastic, the composite material is commonly referred to as fiberglass.
The glass can be in the form of a chopped strand mat CSM or a woven fabric. Whereas the plastic resins are strong in compressive loading and relatively weak in tensile strength, the glass fibers are very strong in tension but tend not to resist compression. By combining the two materials, GRP becomes a material that resists both compressive and tensile forces well.
It is also used to reinforce various materials, such as tent poles, pole vault poles, arrows, bows and crossbows, translucent roofing panels, automobile bodies, hockey sticks, surfboards, boat hulls, and paper honeycomb.
It has been used for medical purposes in casts. Glass fiber is extensively used for making FRP tanks and vessels.
Use of glass-fiber reinforced polymer rebar instead of steel rebar shows promise in areas where avoidance of steel corrosion is desired. Another potential use is within electronic applications as sodium based glass fibers assist or replace lithium in lithium-ion batteries due to its improved electronic properties.
Role of recycling in glass fiber manufacturingManufacturers of glass-fiber insulation can use recycled glass.
The Orders set out in the First Schedule to this Order are hereby revoked. Edible vegetables and certain roots and tubers. Edible fruit and nuts; peel of melons or citrus fruit. Coffee, tea, mate and spices Cereals Products of the milling industry; malt and stal'ches ; gluten; inulin.
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Abrasive grains of fused alumina Abrasive grains of silicon carbide Abrasive grains, synthetic, others Abraive paper, n. Absorbent cotn Accelerars, electron pron, complete Accelerars, electron pron, complete-parts of Accelerars, rubber prepared Accordions etc. Accounting calculating machines Accoustic tiles of insulation boards Acetarsol B. Acetylsalicylic acid Accumular cases separars, hard rubber Accumulars, electric, parts of. Accumulars, electric srage batteries Acetals, hemiacetals derivatives Acetanilide Acetate butyrate sheets, rods tubes Acetate rayon filament yam Acetate rayon spun yam Acetate rayon ps.
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From Wikipedia, the free encyclopedia Jump to navigation Jump to search Material consisting of numerous extremely fine fibers of glassFor the common composite material reinforced with glass fibers, see Fiberglass. For the glass fiber used to transmit information, see Optical fiber. Bundle of glass fibersGlass fiber or glass fibre is a material consisting of numerous extremely fine fibers of glass. Glassmakers throughout history have experimented with glass fibers, but mass manufacture of glass fiber was only made possible with the invention of finer machine tooling. In , Edward Drummond Libbey exhibited a dress at the World's Columbian Exposition incorporating glass fibers with the diameter and texture of silk fibers. Glass fibers can also occur naturally, as Pele's hair. Glass wool, which is one product called 'fiberglass' today, was invented in — by Russell Games Slayter of Owens-Corning, as a material to be used as thermal building insulation. Glass fiber when used as a thermal insulating material, is specially manufactured with a bonding agent to trap many small air cells, resulting in the characteristically air-filled low-density 'glass wool' family of products. Glass fiber has roughly comparable mechanical properties to other fibers such as polymers and carbon fiber. Although not as rigid as carbon fiber, it is much cheaper and significantly less brittle when used in composites.
Words ending with s in the mammoth censored word list.
Artefacts and environmental remains are abundant from archaeological excavations across Europe, but until now they have most commonly been used to accompany broader narratives built on historical sources and studies of topography and buildings, rather than being studied as important evidence in their own right. The papers in this volume aim to redress the balance by taking an environmental and artefact-based approach to life in medieval Europe. The contributions included here address central themes such as urban identities, the nature of towns and their relationship with their hinterlands, provisioning processes, and the role of ritual and religion in everyday life. Case studies from across Europe encourage a comparative approach between town and country, and provide a pan-European perspective to current debates. The volume is divided into four key parts: an exploration of the processes of provisioning; an assessment of the dynamics of urban population; an examination of domestic life; and a discussion of the status quaestionis and future potential of urban environmental archaeology. Together, these sections make a significant contribution to medieval archaeology and offer new and unique insights into the conditions of everyday life in medieval Europe.
Archaeology of Culture Contact and Colonialism in Spanish and Portuguese America
Singapore Standard Industrial Classification - Statistics No part of this publication may be reproduced in any material form including photocopying or storing it in any medium by electronic means and whether or nottransiently or incidentally to some other use of this publication without the prior writtenpermission of the copyright owner except in accordance with the provisions of the CopyrightAct Cap. The Actguarantees the confidentiality of information collected relating fromindividuals and companies. It spells out the legislative authority andresponsibility of the Chief Statistician. The adoption and use ofthese standards in the collection, analysis and dissemination of statistics ensureconsistency and comparability of data, facilitating relevant and meaningful analysis aswell as data sharing. The SSIC is usedfor censuses of population, household and establishment surveys and increasingly, inadministrative databases. It is reviewed and updatedregularly to reflect significant changes in the structure of the Singapore economy andthe emergence of new activities as well as to align with changes in the internationalstandard. This publication includes the industrial codes, scope and structure of theclassification as well as descriptions of the principles.
Archaeology of Culture Contact and Colonialism in Spanish and Portuguese America contributes to disrupt the old grand narrative of cultural contact and colonialism in Spanish and Portuguese America in a wide and complete sense. This edited volume aims at exploring contact archaeology in the modern era.
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Ради своего собственного спокойствия ему следует возвратиться в Диаспар, искать у него защиты, пока он не преодолеет свои мечты и честолюбивые устремления. Здесь таилась некая насмешка: тот же самый человек, который оставил свой город ради попытки отправиться к звездам, возвращался домой, как бежит к матери испуганный чем-то ребенок.
А мы -- нет, поскольку нам свойственна боязнь высоты. Да, пусть она иррациональна, но она слишком уж сильна, чтобы ее можно было игнорировать.
Она встроена в .
По-видимому, он был способен -- как и многие человеческие существа до него -- примирять два противоречащих друг другу ряда фактов. Теперь он прослеживал свои воспоминания в обратном направлении -- к источнику их происхождения.
Почти потерявшись в сиянии Центрального Солнца, лежала бледная искорка, вокруг которой поблескивали уж совсем крохотные миры. Необъятное по масштабам путешествие приближалось к концу.