Mindfulness, operational

New ideas emerge dimly into intuition, come into consciousness from nobody knows where, and become the material on which the mind operates, forming them gradually into a consistent doctrine, which can be welded onto existing domains of knowledge. But this process is never complete a crude connection can always be pointed to by a logician as an indication of the imperfection of human constructions. 

Afterwards the subject is asked to deduce a possible logical relation between the several types of generic objects, now shown continuously, in one case with the reference object shown, and in another case without the reference. To deduce any one of the several possible logical relations between the generic objects requires a logical sequence of brain/mind operations, including attention and... 

For a description of the way your mind operates, look up Mercury in the Appendix and read the appropriate paragraph in this list ... 

Choice of reactor. The first and usually most important decisions to be made are those for the reactor type and its operating conditions. In choosing the reactor, the overriding consideration is usually raw materials efficiency (bearing in mind materials of construction, safety, etc.). Raw materials costs are usually the most important costs in the whole process. Also, any inefficiency in raw materials use is likely to create waste streams that become an environmental problem. 

Quantum mechanics is cast in a language that is not familiar to most students of chemistry who are examining the subject for the first time. Its mathematical content and how it relates to experimental measurements both require a great deal of effort to master. With these thoughts in mind, the authors have organized this introductory section in a manner that first provides the student with a brief introduction to the two primary constructs of quantum mechanics, operators and wavefunctions that obey a Schrodinger equation, then demonstrates the application of these constructs to several chemically relevant model problems, and finally returns to examine in more detail the conceptual structure of quantum mechanics. 

The results given above are, as stated, general. Any and all angular momenta have quantum mechanical operators that obey these equations. It is convention to designate specific kinds of angular momenta by specific letters however, it should be kept in mind... 

As of the year 1998, small quantities of sassafras oil are still being sold on retail shelves without any scrutiny. Usually in 1-4oz sizes. Anything larger is usually sold only through distributors and manufacturers. And as of 1998, the DEA has informed most of these distributors that they (the DEA) want lists kept or sales reported of most, if not all, sassafras oil purchases. Mind you it is not illegal to buy the oil. It s just that you will be put on a list if you do. The operative term here is Watched Substance . Solution have someone else buy it for you. 

Operations such as the above are carried out very rapidly by the computer through voltage switching, each switch lasting only a few nanoseconds. Therefore, although it is clumsier to represent numbers in binary for the human mind, and instead we use ten symbols (0, 1,. .., 9) to help us with complicated arithmetic, the speed with which we can do this arithmetic is nothing like the speed of the computer. Computer addition seems instantaneous, whereas human response to addition takes a finite time. 

The relatively low flash points of some acrylates create a fire hazard. Also, the ease of polymerization must be home in mind in ah. operations. The lower and upper explosive limits for methyl acrylate are 2.8 and 25 vol %, respectively. Corresponding limits for ethyl acrylate are 1.8 vol % and saturation, respectively. All possible sources of ignition of monomers must be eliininated. 

There are four overall guidehnes that analysts should keep in mind. They must recognize the difficulties associated with the limited number and accuracy of the data, overcome the plant operation mythologies, overcome the designers and controllers biases and, finally, override the analysts own prejudices. The following four overall guidelines assist in overcoming the hurdles to proper plant performance. 

Measurement Selection The identification of which measurements to make is an often overlooked aspect of plant-performance analysis. The end use of the data interpretation must be understood (i.e., the purpose for which the data, the parameters, or the resultant model will be used). For example, building a mathematical model of the process to explore other regions of operation is an end use. Another is to use the data to troubleshoot an operating problem. The level of data accuracy, the amount of data, and the sophistication of the interpretation depends upon the accuracy with which the result of the analysis needs to oe known. Daily measurements to a great extent and special plant measurements to a lesser extent are rarelv planned with the end use in mind. The result is typically too little data of too low accuracy or an inordinate amount with the resultant misuse in resources. 

Listed below are operator related safety issues that are more prevelant in batch operations. Keep in mind, however, that human error consists of more facets than operator error alone. 

QRA practitioners can use to satisfy some QRA objectives. Also, the American Institute of Chemical Engineers (AIChE) has sponsored a project to expand and improve the quality of component failure data for chemical industry use. And many process facilities have considerable equipment operating experience in maintenance files, operating logs, and the minds of operators and maintenance personnel. These data can be collected and combined with industrywide data to help achieve reasonable QRA objectives. However, care must be exercised to select data most representative of your specific system from the wide range available from various sources. Even data from your own plant may have to be modified (sometimes by a factor of 10 or more) to reflect your plant s current operating environment and maintenance practices. 

To summarize the importance of the critical speed concept, one should bear in mind that it allows an identification of the operation region of the rotor-bearing system, probable mode shapes, and approximate locations of peak amplitudes. 

It is not a bad idea for the process engineer to familiarize himself with compressor surge controls. The interaction of the compressor surge controls with downstream process control valves can become a problem area later, and this study phase is not too early to put such items on a checklist. An LNG plant example comes to mind where such an operating problem existed. 

Keep in mind rail tariff breaks for numbers of cars in a string so that the ability to handle the required numbers can be provided. If the operation is large enough, as for large coal mining operations, unit trains (100 cars) are used. 

Several steps can be taken to maximize the run time for the reciprocating compressor. Since wear is a function of rubbing speed, the piston speed can be kept to a minimum. Chapter 3 made recommendations for piston speed. Reliability problems due to valves are reputed to account tor 40% of the maintenance cost of the compressor. Valves are the single largest cause for unplanned shutdowns. Basically, valve life can he increased by keeping the speed of the compressor as low as practical. At 360 rpm, the valves are operated six times a second. At 1,200 rpm, ihc valves operate 20 times a second or 1,728,000 times in a day. It is not difficult to understand why the valves are considered critical. To keep the reliability in mind, valve type, material selection and application considerations such as volume ratio, gas corrosiveness, and gas cleanliness need attention by the experts. One final note is that while lubrication is an asset to the rubbing parts, it is not necessarily good for valve reliability. 

For calibration of the 0 to 100% LEL scale, test kits containing known concentrations of combustible gases (usually either 2.5% methane or 2.5% natural gas) are available from the instrument manufacturers. In using these kits, it should be borne in mind that the calibration is only for that sjiecific gas and indicates only that the meter is operational on the 0 to 100% LEL scale. To calibrate to 0 to 10% scale, it is necessary to use purchased or specifically prepared known concentrations of gases in the TLV ranges. 

Some general considerations to bear in mind are (1) In all start-up and shutdown operations, fluid flows should be regulated so as to avoid thermal shocking the unit, regardless of whether the unit is of either a removable or non-removable type of construction (2) For fixed tubesheet (i.e., non-removable bundle) type units, where the tube side fluid cannot be shut down, it is recommended that both a bypass arrangement be incorporated in the system, and the tube side fluid be bypassed before the shell side fluid is shut down (3) Extreme caution should be taken on insulated units where fluid flows are terminated and then restarted. Since the metal parts eould remain at high temperatures for extended periods of time, severe thermal shock could occur. 

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