Tuesday, March 29, 2011

Çağatay Kadir Aktaş, 030060176, 7th week

Pyrolysis: (21:15)
Pyrolysis is the chemical decomposition of organic materials by heating in the absence or controlled amount of oxygen. Pyrolysis and gasification are thermo-chemical conversion routes which recovers energy from biomass and waste fuels. Pyrolysis is heavily used in the chemical industry, for example, to produce charcoal, activated carbon, methanol and other chemicals from wood. It is an important chemical process in several cooking procedures such as baking, frying and grilling. Pyrolytic processes are involved in basic research as well as in applied fields such as the industry. This book will survey the use of the pyrolysis in these fields and will also examine current research done in the nanoscience field.
(Walker S. Dnahue, Jack C. Brandt, Types, Processes, and Industrial Sources and Products, pg:259)

Black Orlon: (21:40)
Black Orlon is a ladder polymer obtained by regulated pyrolysis of polyacrylonitrile. Fibres of black orlon are highly tough and find applications in fibre reinforced plastics. The structure of black orlon has carbon hydrogen and nitrogen atoms. It's a special structure which have bonds between these atoms.
(
A.K. Bhargava, Engineering Materials: Polymers Ceramics and Composites, pg:118)

Thermal anemometers: (22:00)
Thermal anemometers measure fluid velocity by sensing the changes in heat transfer from a small, electrically heated sensor exposed to the fluid motion. Their generally small size and good frequency response makes them especially suitable for studying flow details, particularly in turbulent flow.

In many applications, fluid tempereture, composition, and pressure are constant, so the only variable affecting heat transfer is fluid velocity. When other parameters vary,
accurate velocity measurements with a thermal sensor become more difficult. At the same time, sentivity of thermal sensors to other fluid parameters presents the
possibillity of measuring more than just velocity by using more than one sensor.
(Richard J. Goldstein,Fluid Mechanics Measurements, pg:115)

In-transit inventory: (22:18)
During transportation goods are also in stock, even if they are not available for use. The calculation of in-transit inventory is fairly obvious. Goods are held in inventory fort he duration of the in-transit period. All this time they are subject to inventory costs, which, no less than when they are in the storage, comprise interest costs, insurance costs and depreciation. There is this difference, that in-transit inventory generates no warehousing costs. There might, on the other hand, be a slightly higher insurance cost, for there is a greater risk factor during transportation than in the warehouse.

In-transit inventory mus not be underestimated. In volume it can surpass cycle stock. For example, if a firm replenishes its stock on a regular monthly basis, an average tonne of goods will remain in cycle stock for only a fortnight. It is quite possible that the total transportation time, say from an overseas origin, exceeds a fortnight. Thus the goods actually spend a longer time in transit thant they do in the cycle stock.

In-transit inventory costs have a very different effect from cycle stock costs on transport decisions. Cycle stock costs encourage transportation in small consignments, whereas in-transit inventory costs encourage a faster mode of transport. This difference is frequently overlooked, because the fastest means of transport also tend to carry the smallest consignments. Since the two elements overlap, the difference easily goes unnoticed. In essence, however, they are quite different.
(Gust Blauwens,Peter De Baere,Eddy Van de Voorde, Transport Economics, pg:205)

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