Requirements Engineering

Finally, two other characteristics of hard materials are important their density and their chemical stability. The importance of these properties depends on the application. Oxides are chemically more stable than nitrides, which are in turn more stable than borides or carbides. The susceptibility to oxidation of boron carbide prevents its application at high temperatures, but for ballistic protection, where hardness, rigidity and low density take precedence, boron carbide is unparalleled. Tungsten carbide, on the other hand, is the material of first choice for cutting tools, because of its high hardness and stiffness, and high-temperature oxidation resistance, but is far too dense for application in which weight or inertial forces are important. Its use for ballistic protection is therefore out of the question. 

Hard materials available for the production of bulk components fall into two major groups hard metals , used primarily in the manufacture of cutting tools and related applications, and structural ceramics, primarily the oxides, carbides, borides, or nitrides of the low atomic number cations. Relatively few materials are of engineering importance, and we will list these, explaining briefly why similar compositions are less useful. 

1 Tungsten Carbide-Cobalt, Tungsten Carbide-Nickel, 

The success of hard metals in cutting tool applications is a result of their unique combination of hardness and toughness, tailored by controlling the ratio of binder to carbide phase, together with their unique microstructure. Both the ductile binder 

Selectivity is also needed to produce pure products in high yields, a characteristic which is very important in the preparation of pharmaceuticals, intermediates for polymers and many other applications. Prices of chemicals vary drastically with its purity grade. Often high purity is a necessity as in polymer grade propene or olefins for metathesis. This is 

The formation of by-products can also lead to a market problem in selling or discarding the latter ones, thus impacting the economics of a process. No industry likes processes with two or more products because balance on the market normally is quite difficult. In addition, disposal of by-products could become more difficult in the future. 

Besides selectivity, energy requirements will grow more essential in the future. One advantage of homogeneous catalysis lies in its mild reaction temperatures needed for reactions to occur. Also working in solution makes heat recovery especially in exothermic reactions — often much easier. For instance, reflux of a solvent can be used to control the temperature in a reaction vessel. 

Also benefits in diffusion control may be cited among the advantages. Heterogeneous catalysts are often plagued by diffusion limitations which are practically unknown or can be much easier solved in homogeneous systems. 

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In a general manner, diesel engines, jet engines, and domestic or industrial burners operate with lean mixtures and their performance is relatively insensitive to the equivalence ratio. On the other hand, gasoline engines require a fuel-air ratio close to the stoichiometric. Indeed, a too-rich mixture leads to an excessive exhaust pollution from CO emissions and unburned hydrocarbons whereas a too-lean mixture produces unstable combustion (reduced driveability and misfiring). 

Unlike spark-induced combustion engines requiring fuel that resists autoignition, diesel engines require motor fuels, for vhich the reference compound is cetane, that are capable of auto-igniting easily. Additives improving the cetane number will promote the oxidation of paraffins. The only compound used is ethyl-2-hexyl nitrate. 

ERD wells are technically more difficult to drill and because of the degree of engineering required for each well the term designer well is frequently used. 

Moser, C.C., Dutton, P.L. Biological electron transfer measurement, mechanism, engineering requirements. In Quantum mechanical simulation methods for studying biological systems, D. Bicout and M. Field, eds. Springer, Berlin (1996) 201-214. 

The requiiements for scientific software development have continually increased. Besides the algorithmic core functionality, nowadays there is often a demand for a graphical user interface. In addition to the increasing importance of this visible component, which may still be seen as just an add-on, the software development itself has to fulfill stronger demands on software engineering requirements, such as maintainability and recoverability. 

The fundamental chemistry and engineering requirements of the process have been studied and ate described elsewhere (23,24). 

Material property specifications must be written by design and material engineers to control engineering requirements and to control incoming raw material quahty. Material property requirements depend on various ia-use functional needs ia terms of electrical, mechanical, thermal, chemical, optical, and magnetic properties. 

The processes of cathodic protection can be scientifically explained far more concisely than many other protective systems. Corrosion of metals in aqueous solutions or in the soil is principally an electrolytic process controlled by an electric tension, i.e., the potential of a metal in an electrolytic solution. According to the laws of electrochemistry, the reaction tendency and the rate of reaction will decrease with reducing potential. Although these relationships have been known for more than a century and although cathodic protection has been practiced in isolated cases for a long time, it required an extended period for its technical application on a wider scale. This may have been because cathodic protection used to appear curious and strange, and the electrical engineering requirements hindered its practical application. The practice of cathodic protection is indeed more complex than its theoretical base. 

First part qualification. First part qualification is a process performed the first time a new bonded assembly is manufactured or the first time a new tool is used to manufacture a bonded assembly. First part qualification provides assurance that all of the aspects that control bond assembly quality, such as the design dimensions, detail part manufacturing techniques, tool dimensions, layup procedures and autoclave cure cycle parameters are correct and will produce a bond assembly that meets the engineering requirements. 

Although the table is outside the scope of most industrial ventilating engineering requirements, it does indicate the many problems to be considered in the measurement techniques. 

The fan is the heart of a ventilation system. The industrial engineer requires a comprehensive working knowledge of the subject of fan engineering for the following reasons ... 

The product approval process, or PPAP as it is known in QS-9000, is intended to validate that products made from production materials, tools, and processes meet the customer s engineering requirements and that the production process has the potential to produce product meeting these requirements during an actual production run at the quoted production rate. 

Just as an internal combustion engine requires fuel to do work, animals need fuel to power their body processes. Animals Cake in complex molecules as food and break them down to release the energy they contain. This process is called catabolism. Animals use the energy of catabolism to do work and to assemble complex molecules of their own from simple building blocks, a process called anabolism. The sum of anabolism and catabolism is metabolism, a broad term that includes all chemical reactions in the body. 

There are many other factors which affect project planning as it is related to process engineering. However, these are usually peculiar to the process or objective of the project. On first glance some of the items listed in Table 1-11 may appear to be unrelated to the process engineering requirements, and this can be the case for some types of projects. In these situations they become more of a project engineering responsibility. However, in many cases these have a relationship either to the process engineering requirements or to the decisions which must take this into account. 

In-place specific weight tests are used to correlate field compaction results with specified engineering requirements for specific weight. 

Preamble. Engineering is an important and learned profession. The members of the profession recognize that their work has a direct and vital impact on the quality of life for all people. Accordingly, the services provided by engineers require honesty, safety and welfare. In the practice of their profession, engineers must perform under a standard of professional behavior which requires adherence to the highest principles of ethical conduct on behalf of the public, clients, employers and the profession. 

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