Workloads

Further improvements on typical signal distance rules will certainly reduce the tremendous workload of online analysis. This new approach will lead to a reduction of the on-site analyst team. 

Parallel molecular dynamics codes are distinguished by their methods of dividing the force evaluation workload among the processors (or nodes). The force evaluation is naturally divided into bonded terms, approximating the effects of covalent bonds and involving up to four nearby atoms, and pairwise nonbonded terms, which account for the electrostatic, dispersive, and electronic repulsion interactions between atoms that are not covalently bonded. The nonbonded forces involve interactions between all pairs of particles in the system and hence require time proportional to the square of the number of atoms. Even when neglected outside of a cutoff, nonbonded force evaluations represent the vast majority of work involved in a molecular dynamics simulation. 

Air-Atmosphere Furnaces. These furnaces are appHed to processes where the workload can tolerate the oxidation that occurs at elevated temperatures in air. In some special appHcations, the oxidation is not only tolerable but is desired. Some furnaces heat the work solely to promote oxidation. Furnaces designed for air operation are not completely gas-tight which results in somewhat lower constmction costs. There are no particular problems encountered in selecting the insulation systems because almost all refractory insulations are made up of oxides. Heating element materials are readily available for the common temperature ranges used with air atmospheres. 

Heat. Personal monitoring of the environmental conditions which impose a heat stress on a worker is impractical, so fixed station measurement of such parameters as wet bulb globe temperature are usually made (see Temperature measurements). These stations are carefully selected so that the results, plus worker location and workload data, can be combined to yield an overall heat stress estimate. Heat strain, the effect on the human, can be estimated from core body temperature, but this is usually only a research tool. 

Workload status and the justification of equipment Regulatory agency compliance Audit trail for all database transactions Security class or hierarchy... 

Assay of Enzymes In body fluids, enzyme levels aie measured to help in diagnosis and for monitoiing treatment of disease. Some enzymes or isoenzymes are predominant only in a particular tissue. When such tissues are damaged because of a disease, these enzymes or isoenzymes are Hberated and there is an increase in the level of the enzyme in the semm. Enzyme levels are deterrnined by the kinetic methods described, ie, the assays are set up so that the enzyme concentration is rate-limiting. The continuous flow analyzers, introduced in the early 1960s, solved the problem of the high workload of clinical laboratories. In this method, reaction velocity is measured rapidly the change in absorbance may be very small, but within the capabiUty of advanced kinetic analyzers. 

An advantage of pack carburizing is that the charcoal pack supports the workload which minimizes distortion. However, the components must be removed from the pack for quenching, or the mass cooled to room temperature and then the components reaustenitized and quenched. 

Ca.rdia.c-AssistDevices. The principal cardiac-assist device, the intra-aortic balloon pump (lABP), is used primarily to support patients before or after open-heart surgery, or patients who go into cardiogenic shock. As of the mid-1990s, the lABP was being used more often to stabilize heart attack victims, especially in community hospitals which do not provide open-heart surgery. The procedure consists of a balloon catheter inserted into the aorta which expands and contracts to assist blood flow into the circulatory system and to reduce the heart s workload by about 20%. The disposable balloon is powered by an external pump console. 

Mean arterial pressure and cardiac output, an expression of the amount of blood that the heart pumps each minute, are the key Indicators of the normal functioning of the cardiovascular system. Mean arterial pressure is strictly controlled, but by changing the cardiac output, a person can adapt, e.g., to increased oxygen requirement due to increased workload. Blood flow in vital organs may vary for many reasons, but is usually due to decreased cardiac output. However, there can be very dramatic changes in blood pressure, e.g., blood pressure plummets during an anaphylactic allergic reaction. Also cytotoxic chemicals, such as heavy metals, may decrease the blood pressure. 

Human Factors Engineering/Ergonomics approach (control of error by design, audit, and feedback of operational experience) Occupational/process safety Manual/control operations Routine operation Task analysis Job design Workplace design Interface design Physical environment evaluation Workload analysis Infrequent... 

From the 1960s onward, there was a greater interest in psychological issues, dominated by the concept of the human as a single-channel processor of information. This stimulated research into a number of areas. Studies of mental workload were concerned with the ability of humans to cope with extremely high levels of information in situations such as air traffic control. Vigilance studies, which focused on the human s role in situations with very low levels of stimulation such as radar monitoring, represented the other extreme of human performance that was considered. 

Decision making may involve calculations, reference to procedures and past experience, and other demands on long-term memory. This contributes further to the overall mental workload. From the HF/E perspective, many errors are likely to arise from information processing overload, essentially from the mismatch between demands and capabilities. Information-processing demands can be reduced by the provision of information in the form of job aids such as flow charts or decision trees. 

Many of the difficulties in using operating procedures stem from the fact that the conditions for applying a given section or branch and the conditions for completing or transferring to another section are not clearly specified. This is particularly important in emergency situations where a choice must be made under time pressure and excessive workload. 

On many occasions, new equipment is installed or process workers have to work in other similar plant units in order to substitute for one of their colleagues. Despite the overall similarity of the new equipment, there might be some differences in their operation which may sometimes become very critical. We caimot always rely on the operator to discover these potentially critical differences in equipment design, especially under time pressure and excessive workload. If multiskill training in a range of plant equipment is not feasible, then training should be provided for the specific new equipment. The incident below was due to lack of training for a caimed pump. 

Conditions of health and age play an important role in human performance. Job demands will determine the general fitness and age of the workers to be employed for a particular job. Recent illness can affect the level of alertness, the required concentration on the job, and the capability to cope with high workload. 

To judge the quality of team performance it is necessary to examine the following PIFs distribution of workload, clarity of responsibilities, communications, team structure and leadership, and finally, group planning and orientation. 

The distribution of workload among the members of the team will determine the extent of task overload or task vmderload for each person. It is widely recognized that reliabihty decreases when people have too much or too little to do. The incident which is described below occurred because of suboptimal allocation of tasks to team members. 

Signal-flow graphs are particularly useful in two respects. First, they make the process designer examine in considerable detail the dynamic structure and fimctioning of the process. Second, the nature of the interface between person and machine can be seen more clearly. The variables that are displayed in a system are, of course, available for study, but workers frequently respond to derivative functions of variables or "hidden" variables that must be deduced. Given that the process variables to be displayed will influence the worker s control strategy and that the number of deductions to be made will affect the mental workload involved, a process designer can select the type and amoimt of process information which will enhance performance of the task. 

Another limitation concerns the duplication of process information on different VDU pages. Specifically, most of the data on the graphic displays were presented again in a different format on the text displays. This increased the number of VDU pages used in total to perform a task. This secondary navigation task undoubtedly increased the workload of the worker who had to control the process. Within the text displays themselves, information was not structured in a functional manner. TTiat is, information required by workers was... 

Delays are caused by workload and communication load problems. 

Forget to blowdown (due to workload, distractions, or low prominence of information). 

A selection of the recommendations which were produced are presented below and cover most aspects of the blowdown operation. However, their common underlying theme is to provide optimum decision support in a high stress, high workload emergency situation such as a significant fire or gas release. 

The most likely means of rectifying the very high workload and error rates which are likely to occur, would be to make use of the VDUs in the control room to provide important information in a centralized location, perhaps also in certain cases to effect control actions. This would be especially useful in one of the platform control rooms, since it was never intended to be a centralized control room, and there were therefore many information limitations which could probably only be compensated for by providing VDU information. 

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