Structures economics

The fundamental requirements of a sacrificial anode are to impart sufficient cathodic protection to a structure economically and predictably over a defined period, and to eliminate, or reduce to an acceptable level, corrosion that would otherwise take place. 

Thompson, R. G., Stone, J. C., Singleton, F. D., Jr., and Raghaven, S. "Predicting the Structural Economic Consequences of Different Interrelated Energy and Environmental Policies," technical report to the Electric Power Research Institute, July, 1978 (draft). 

Thomas, P.G. 2000. An approach to dynamic environmental life-cycle assessment by evaluating structural economic sequences. Dissertation, Tufts University. 

The interplay of this complex mix of hard and soft factors is best understood by applying a business dynamics approach. A business dynamics model can, for example, simulate the cost structure, economics and investment behavior of a group of players in a commodity industry. The output is the financial performance of the industry - and even of individual players - over time. 

The problems associated with discarded batteries from the highly distributed domestic sources are complicated. They involve questions of social structures, economics, technology, and regulatory climates. The first problem is that of the efficient retrieval of discarded batteries. The next question that must be answered is what kinds of batteries may be allowed to enter municipal waste streams without treatment Another question is how will the consumers know which is which This is related to the question of the amounts of pollutants contributed by particular batteries relative to other sources of the same pollutants. It is not reasonable to consider batteries alone as a problem from the point of view of municipal solid waste (MSW) treatments when other sources contribute the same pollutants as well. Nickel/cadmium batteries are an example. Sources other than batteries contribute significant amounts of cadmium to MSW. The elimination of nickel/cadmium batteries from MSW or the elimination of cadmium from Ni/Cd batteries will not solve problems attributed to cadmium in MSW. 

Multicomponent reactions (MCRs) have attracted much attention in the past decade because of advantages such as high atom economy, simple procedure, and high efficiency. [1] Because of their ability to generate complex structures economically and efficiently [2], numerous MCRs have been developed and widely studied, such as the Cu-catalyzed three-component reactions [3-6], Mannich reactions [7, 8], Passerini reactions [9, 10], and A3-coupling reactions [11]. Of these, multicomponent alkyne reactions have become quite popular recently and abundant literature has been published regarding the various MCRs of alkynes with all sorts of reactants [12, 13]. 

This approach to synthesis is one of making a series of best local decisions. Equipment is added only if it can be justified economically on the basis of the information available, albeit an incomplete picture. This keeps the structure irreducible, and features which are technically or economically redundant are not included. 

The preceding definitions of economic potential and total annual cost can be simplified if it is accepted that they will be used to compare the relative merits of difierent structural options in the flowsheet and difierent settings of the operating parameters. Thus items which will be common to the options being compared can be neglected. 

A catalyst is a material that accelerates a reaction rate towards thennodynamic equilibrium conversion without itself being consumed in the reaction. Reactions occur on catalysts at particular sites, called active sites , which may have different electronic and geometric structures than neighbouring sites. Catalytic reactions are at the heart of many chemical industries, and account for a large fraction of worldwide chemical production. Research into fiindamental aspects of catalytic reactions has a strong economic motivating factor a better understanding of the catalytic process... 

More than 10 000 databases exist that provide a small or large amount of data on various topics (including chemistry). The contents in databases are supplied by approximately 3500 database developers (e.g., the Chemical Abstracts Service, MDL Information Systems, etc.). Since there is a variety of topics from economics to science, as well as a variety of structures of the database, only some of the vendors (-2000) offer one or more databases as either local or as online databases (Figure 5-4) [4]. Usually, databases are provided by hosts that permit direct access to more than one database. The search occurs primarily through different individual soft-... 

We have exemplified the principal methods for allenes, cumulenes and also some new methods for acetylenic compounds by procedures for relatively simple structures. For each of the compounds the most suitable and economic method was selected. 

An important concern to chemists is synthesis the challenge of preparing a particular compound m an economical way with confidence that the method chosen will lead to the desired structure In this section we will introduce the topic of synthesis emphasiz mg the need for systematic planning to decide what is the best sequence of steps to con vert a specified sfarfmg mafenal fo a desired producf (fhe target molecule)... 

I. B.Joralemon, Copper. The Encompassing Sto of Mankind s First Metal, H.owe]l-Notth Books, Berkeley, Calif., 1973. R. F. Mikesell, The World Copper Industry Structure and Economic Mnaljsis,]o m.s Hopkins Press, Baltimore, Md., 1979. 

The half-pipe jacket is used when high jacket pressures are required. The flow pattern of a liquid heat-transfer fluid can be controlled and designed for effective heat transfer. The dimple jacket offers structural advantages and is the most economical for high jacket pressures. The low volumetric capacity produces a fast response to temperature changes. 

Economic and process considerations usually dictate that agitated thin-film evaporators be operated in single-effect mode. Veiy high temperature differences can then be used many are heated with Dowtherm or other high-temperature media. This permits achieving reasonable capacities in spite of the relatively low heat-transfer coefficients and the small surface that can be provided in a single tube [to about 20 m" (200 ft")]. The structural need for wall thicknesses of 6 to 13 mm (V4 to V2. in) is a major reason for the relatively low heat-transfer coefficients when evaporating water-like materials. 

FIG. 14-79 Cost of trays in plate towers. Price includes tray deck, bubble caps, risers, downcomers, and structural-steel parts. The stainless steel designated is type 410 Peters and Timmerhaus, Plant Design and Economics for Cbemical Engineers, 4th ed., McGraw-Hill, New York, 1.9.91). 

When both solids and gases pass through the distributor, such as in catalytic-cracldng units, a number of variations are or have been used, such as concentric rings in the same plane, with the annuli open (Fig. 17-9a) concentric rings in the form of a cone (Fig. 17-9b) grids of T bars or other structural shapes (Fig. 17-9c) flat metal perforated plates supported or reinforced with structural members (Fig. 17-9d) dished and perforated plates concave both upward and downward (Fig. 17-9e and f). The last two forms are generally more economical. 

The most commonly used warehouse chain conveyor is the tow chain. Chain may be mounted overhead or in the floor, and trucks being towed can be designed for automatic detachment at a specific point. While the overhead chain is often used and is usually easy to support from structural members in the ceihng, the in-floor chain is probably most common. Automatic disengagement is possible should trucks encounter an obstruction or accident ly strike warehouse personnel. The two-chain conveyor is, of course, most economical when large tonnages are moved over a fixed path. 

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