Concepts and Units

Define or explain the following terms energy, system, closed system, nonflow system, open system, flow system, surroundings, property, extensive property, intensive property, state, heat, work, kinetic energy, potential energy, internal energy, enthalpy, initial state, final state, point (state) function, state variable, cyclical process, and path function. 

Select and define a system suitable for problem solution, either closed or open, steady or unsteady state, and fix the system boundary. 

Distinguish among potential, kinetic, and internal energy. 

List and apply the equations used to calculate kinetic energy, potential energy, and work. 

What units are associated with energy If you have forgotten, refer back to -Table-lvl—No - confiision-exists -with-respect-tO-the ioule.. but it is necessary tp be careful in specifying what type of calorie or British thermal unit (Btu) is under consideration (there are four or five common kinds). For example, the type of calorie that is found in older tables of thermochemical properties of substances is the thermochemical calorie (equal to 4.184 J), whereas a second type of calorie is the International Steam Table (I.T.) calorie (equal to 4.1867 J). A kcal in nutrition is just called a calorie that is, a hamburger containing 500 calories really contains 500 kcal. 

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This example involves concepts and units which may be unfamiliar to you, so that you can t easily judge whether the result "makes sense," so we ll check the answer by estimation. Write each term in exponential notation, using just one significant figure. Then mentally combine the powers of 10 and the multipliers separately to estimate the result ... 

RADIOMETRIC AND PHOTOMETRIC CONCEPTS AND UNITS Radiant Flux (Power) and Luminous Flux (Lumen)... 

Concepts like excitation, emission, quantum numbers, and electron volts have aU been introduced in a framework of simple algebra, so in later chapters we can focus on the quantum phenomena with familiarity of concepts and units already in hand. 

The first encounter with fibre science and technology is often frustrated by many unfamiliar terms, concepts and units. Use of a suitable dictionary can help with many problems. ... 

Before considering other concepts and group-theoretical machinery, it should once again be stressed that these same tools can be used in symmetry analysis of the translational, vibrational and rotational motions of a molecule. The twelve motions of NH3 (three translations, three rotations, six vibrations) can be described in terms of combinations of displacements of each of the four atoms in each of three (x,y,z) directions. Hence, unit vectors placed on each atom directed in the x, y, and z directions form a basis for action by the operations S of the point group. In the case of NH3, the characters of the resultant 12x12 representation matrices form a reducible representation... 

The importance of an accurate and complete record of invention caimot be underestimated. The record of invention should serve as the basic document for estabUshing the date of conception and reduction to practice of the invention. The U.S. PTO issues patents to those who are first to invent. In a contest over inventorship, any available record of invention is submitted to the U.S. PTO to estabUsh proof of an inventor s rights. As of January 1, 1996, any inventor from a country belonging to the World Trade Organization may use such evidence before the U.S. PTO. Previously, this type of proof could be rehed upon only if the activity, documented in the notebook, record, etc, was undertaken in the United States. Similarly, activity undertaken after December 8, 1993 in Mexico or Canada may also be rehed upon to prove inventorship. 

Mechanical Expanders Reciprocating expanders are very similar in concept and design to reciprocating compressors. Generally these units are used with inlet pressures of 4 to 20 MPa. These machines operate at speeds up to 500 rpm. The thermal efficiencies (actual enthalpy difference/maximum possible enthalpy difference) range from about 75 percent for small units to 85 percent for large machines. 

Internal reboilers are similar in concept and designed accordingly to the ketde units, but this style does not have a... 

Based on the practical history of scale-up, most fermentation processes for alcohol and organic acid production have followed the concepts of geometric similarity and constant power per unit volume. From the above concept, and as a strong basis for translation of process criteria, only physical properties of the process were considered in the scale-up calculation. For power consumption in an agitated vessel, there is a fixed relation between impeller speed, N, and impeller diameter, l)t. The constant power per unit volume, for a mechanical agitated vessel is given by ... 

The use of stress terminology has been discussed in Chapter 1, where it was pointed out that the value of the term stress in indicating some adverse force or influence lies in its extreme generality, without the need for a precise quantification. Nevertheless it is appropriate that a scientific discipline should be concerned with definable quantities. This will be the starting point for this paper, which will follow the example of Levitt (1972) who applied the concepts and terminology of mechanical stress (force per unit area) and strain (a definable dimension change) to the study of plant responses to the environment. This approach will be developed here in an attempt to incorporate the philosophies behind stress effects into a general treatment of the responses of ecosystems to adverse environmental conditions. 

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