Stress tasks

Increased automation, which frees the operations staff from boring and/or stressful tasks, leading to reduced frequency of operator error. 

Oswego Children s Study participants (N= 122, 46% male) Cord Pb mean =2.0 pg/dl mean at 2.2 years = 4.6 It dI SBP, DBP tested at 9.5 years old using stress tasks Cord Pb significantly associated positively with resting BP no effect on BP with acute stress Gump et al. (2005)... 

Some of the psychological stressors that directly affect mental stress are suddenness of onset duration of stress task speed task load high-jeopardy risk threat of failure boring, repetitive, or meaningless work long, uneventful vigilance periods and distractions (e.g., noise, glare, and flicker). 

The force and moment ia a constrained system can be estimated by the cantilever formula. Leg MB is a cantilever subject to a displacement of and leg CB subject to a displacement Av. Taking leg CB, for example, the task has become the problem of a cantilever beam with length E and displacement of Av. This problem caimot be readily solved, because the end condition at is an unknown quantity. However, it can be conservatively solved by assuming there is no rotation at poiat B. This is equivalent to putting a guide at poiat B, and results ia higher estimate ia force, moment, and stress. The approach is called guided-cantilever method. 

Characterization. The proper characterization of coUoids depends on the purposes for which the information is sought because the total description would be an enormous task (27). The foUowiag physical traits are among those to be considered size, shape, and morphology of the primary particles surface area number and size distribution of pores degree of crystallinity and polycrystaUinity defect concentration nature of internal and surface stresses and state of agglomeration (27). Chemical and phase composition are needed for complete characterization, including data on the purity of the bulk phase and the nature and quaHty of adsorbed surface films or impurities. 

These values are determined by experiment. It is, however, by no means a trivial task to measure the lamina compressive and shear strengths (52,53). Also the failure of the first ply of a laminate does not necessarily coincide with the maximum load that the laminate can sustain. In many practical composite laminates first-ply failure may be accompanied by a very small reduction in the laminate stiffness. Local ply-level failures can reduce the stress-raising effects of notches and enhance fatigue performance (54). 

Working in level A proteetion ean eause a variety of stresses. The equipment is heavy. The pressure to eomplete work tasks during a time frame is intensified beeause work time is limited by air supply. Heat stress ean be a problem, even in the winter. In the summer, the use of eooling vests ean keep you eool but also adds to the weight that you are earry-ing. Typieally, all level A workers have a sharp knife blade so that they ean eut themselves out of the suit if the air supply fails. Realizing that you may have to eut yourself out of this suit in ease of air supply failure adds more potential stress to the situation. 

Respiratory protection should always be carefully considered by a qualified person who is aware of the specific task and site conditions. Similar stresses as those pointed out for Levels A and B can be found... 

The analysis of stresses in the laminae of a laminate is a straight-fonvard, but sometimes tedious, task. The reader is presumed to be familiar with the basic lamination principles that were discussed earlier in this chapter. There, the stresses were seen to be a linear function of the applied loads if the laminae exhibit linear elastic behavior. Thus, a single stress analysis suffices to determine the stress field that causes failure of an individual lamina. That is, if all laminae stresses are known, then the stresses in each lamina can be compared with the lamina failure criterion and uniformly scaled upward to determine the load at which failure occurs. 

It is worth pointing out, however, that personality traits which do not provide people with adequate resources to maintain performance under stress, may compensate by supporting other activities during normal operations. For instance, "externals" may be more cautious than "internals" and take no chances to risk plant safety, while type A personalities may have a greater motivation to progress in their jobs and perfect their skills than type B personalities. Depending on the type of task, some personality traits will produce better performance than others. More research would be needed to develop a better understanding of the relationships between types of task and preferable personality styles. 

These diagrams focus on the temporal or time relationships of operations and they can be used to solve resource allocation problems, to determine whether there is any potential for time stress, and to consider alternative work methods in the execution of a procedure. An example drawn from traditional industrial engineering methods is shown in Figure 4.7. The chart is used to analyze the interaction between people and equipment. As indicated in the summary portion of this chart, there is a high proportion of idle time which would probably indicate the use of alternative procedures in the execution of this task. The chart enables the analyst to see the relationships among the activities of the different components in planning such alternatives. 

Check Road Tanker while filling Provide secondary task involving other personnel. Supervisor periodically checks operation Stress importance of regular checks for safety Provide automatic log-in procedure... 

Modify the basic data according to guidelines provided in the handbook, to reflect differences in the assumed "nominal" conditions and the specific conditions for the task being evaluated. The major factor that is taken in to account is the level of stress perceived by the operator when performing the task. 

There is a written procedure for condenser isolation, but it is normally a simple step-by-step task that is second nature to the operator and is performed from memory. However, imder the threat of a potential vapor cloud explosion, the operator may forget to close the propane valves first (Error A). The HEP in Handbook Table 20-7 5 footnote (.01) is increased by a factor of 5 per Handbook Table 20-16 6a to account for stress. 

Ideally, data bases will have been developed within a company such that predetermined PIFs are associated with particular categories of task. If this is not the case, the analyst decides on a suitable set of PIFs. In this example, it is assumed that the main PIFs which determine the likelihood of error are time stress, level of experience, level of distractions, and quality of procedures. (See Section 5.3.2.6.)... 

These ratings can be interpreted as follows. In the case of the Time Stress PIF, all the operations have a high level of time stress, apart from close test valve, where stress is low. The operators are very experienced in carrying out all the tasks. Distractions are moderately high for close test valve, but otherwise low. Procedures are poor for secure locking nuts and secure blocking device, but above average for the other two tasks. 

Based on the analyst s experience, or upon error theory, it is possible to assign weights to the various PIFs to represent the relative influence that each PIF has on all the tasks in the set being evaluated. In this example it is assumed that in general the level of experience has the least influence on these types of errors, and time stress the most iirfluence. The relative effects of the different PIFs can be expressed by the following weights ... 

An alternative intervention would be to make the procedures ideal (rating = 9). Changing the ratings for procedures to this value for each task (instead of reducing time stress) produces the following results. 

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