Grading variability

A cooperative alliance of Kenetech Corporation, Pacific Gas and Electric Company, Niagara Mohawk Power Corporation, and EPRI has developed an advanced, utility-grade variable speed wind turbine that can deliver 300 kW. Commercially available and in widespread use, the turbine uses advanced power electronics to increase turbine efficiency, improve power quality, and lengthen turbine life. Future efforts are directed at developing turbines capable of individually producing 500—1000 kW for eventual deployment in a large-scale power role. 

Feedstock flexibility The process is capable of treating a wide range of low grade, variable composition cellulosic feedstocks or on proposed dedicated energy crops such as willow, poplar, miscanthus Sp. or switchgrass 41). 

Graded index stmctures allow greater control over fibre characteristics. In these stmctures, the core has a variable... 

Production Technology. A moderately high (33.5% 2 5 BPL) grade of phosphate rock is required for the production of a product that contains 20% available P2 5 Significant process variables in the manufacture of NSP are Hsted in Table 5. 

An example of a classification problem ia which feature weighting and selection was important comes from forensic chemistry (qv). A classification method was needed to determine the paper grade and manufacturer of a paper scrap found at the scene of a crime. In this study, 119 sheets of paper (qv) representing 40 different paper grades and nine manufacturers were obtained (25). The objects were then the paper samples, and the variables consisted of... 

The production rate is 2—4 t/h, depending on the feed rate, monomer concentration in the feed, and conversion. The conversion of isobutylene and isoprene typically ranges from 75—95% and 45—85%, respectively, depending on the grade of butyl mbber being produced. The composition and mol wt of the polymer formed depend on the concentration of the monomers in the reactor Hquid phase and the amount of chain transfer and terminating species present. The Hquid-phase composition is a function of the feed composition and the extent of monomer conversion. In practice, the principal operating variable is the flow rate of the initiator/coinitiator solution to the reactor residence time is normally 30—60 minutes. 

There are many grades of nitrile rubber available on the market today for example, Zeon Chemicals offers approximately 75 different grades of NBR. The principal variables that are commonly changed iaclude the foUowiag ... 

Aluminium fluoride (anhydrous) [7784-18-4] M 84.0, m 250°. Technical material may contain up to 15% alumina, with minor impurities such as aluminium sulfate, cryolite, silica and iron oxide. Reagent grade AIF3 (hydrated) contains only traces of impurities but its water content is very variable (may be up to 40%). It can be dried by calcining at 600-800° in a stream of dry air (some hydrolysis occurs), followed by vacuum distn at low pressure in a graphite system, heated to approximately 925° (condenser at 900°) [Henry and Dreisbach J Am Chem Soc 81 5274 1959]. 

At the present time there are available many hundreds of grades of polyethylene, most of which differ in their properties in one way or another. Such differences arise from the following variables ... 

Note that the wetted surface A used to calculate heat absoiption for a practical fire situation is normally taken to be the total wetted surface within 7.5 m of grade. "Grade" usually refers to ground level, but any other level at which a major fire could be sustained, such as a platform, should also be considered. In the case of vessels containing a variable level of liquid, the average level is considered. Specific inteipretations of A to be used for various vessels are as... 

Timber is derived from a great number of botanical species, and has a wide range of properties. Variability also occurs within a single species and in order to achieve acceptable levels of uniformity, selection by grading is necessary. The timber trade differentiates between softwoods and hardwoods, and the latter are again separated into temperate and tropical types. Hardwoods are derived from broad-leaved and mainly deciduous trees, which are anatomically more complex and differ in chemical composition... 

With the best observing conditions, it is possible for the trained observer to compete with photoelectric colorimeters for detection of small color differences in samples which can be observed simultaneously. However, the human observer cannot ordinarily make accurate color comparisons over a period of time if memory of sample color is involved. This factor and others, such as variability among observers and color blindness, make it important to control or eliminate the subjective factor in color grading. In this respect, objective methods, which make use of instruments such as spectrophotometers or carefully calibrated colorimeters with conditions of observation carefully standardized, provide the most reliable means of obtaining precise color measurements. 

The technology of manufacturing the same basic type or grade of plastics (as with steel and other materials) by different suppliers may not provide the same results. In fact a supplier furnishing their material under an initial batch number could differ when the next batch is delivered and in turn could effect the performance of your product. Taking into account manufacturing tolerances of the plastic, plus variables of equipment and procedure, it becomes apparent that checking several types of materials from the same or from different sources is an important part of material selection and in turn their use. 

---