Control systems, technically complex

Overall, the technical complexity of the Deans switch system is considerably greater than that of a mechanical switching valve and it is accepted that reliability and ease of use is reduced as the system complexity increases. For many compound types, however, the completely non-intrusive nature of the Deans method offers sufficient advantages to justify its application. However, the use of modern electronic pressure and flow controls integrated into the overall computer control of the chromatographic system does now make the operation of Deans switches significantly easier or more reliable than has been reported in its earlier applications. 

Inhalation. The respiratory system is an important portal of entry, and for evaluation purposes animals must be exposed to atmospheres containing potential toxicants. The generation and control of the physical characteristics of such contaminated atmospheres is technically complex and expensive in practice. The alternative—direct instillation into the lung through the trachea—presents problems of reproducibility as well as stress and for these reasons is generally unsatisfactory. 

Within the framework of assembly rationalization, electronics almost has a double effect (Figure 5). In the first step, efficient assembly solutions can be built up by electronically controlled systems with programmable controllers and sensors. In the second step, the assembly task can be completely replaced by an electronically provided function. Examples are the replacement of electromechanicd fluorescent lamp starters by an electronic solution and, on a long-term basis, the replacement of technically complex letter-sorting installations by purely electronic communication via global computer networks. Not only does the replacing electromechanical solutions with electronic functional carriers reduce assembly expenditure, but electronics production can be automated more efficiently. In many cases, the functionality and thus the customer benefit can be increased by the transition to entirely electronic solutions. 

Because of the sophistication of new automated control systems and the complexity of the growing list of responsibilities, the requirements for a process employee changed. No longer can they be someone who could come in off the street without training or experience and be trained for the job in a few days or even a few weeks. The fact that operators, instrumentation technicians, and analyzer technicians are now more frequently referred to as technicians implies a change in their roles. The definition of technical is having special or practical knowledge of a mechanical or scientific subject. 

Due to the worldwide growth in airspace utilization, including the expansion and diversity of military operations, airspace control systems have been increasing their technical complexity, introducing new features into the existent automation or creating additional resources for the automation of some functions previously performed by human operators. Therefore, the dependence on the availabihly of the computer systems involved in the services provided by control centers has increased. Project directives and operational procedures are established in order to maintain the safety integrify levels, in case of any degraded operation event, while availability remains as a critical parameter to the efficiency of the operation services provided by the centers. 

A distributed control system may involve the use of microcomputers at the local level and the use of more powerful rruchines to coordinate overall plant control objectives. In this context, it has been suggested that process control might be described better as process management." " Local control of the operation of individual separators is still important but, with the use of distributed control, reliability is maintained (microcomputers are dedicated to particular process units) while overall technical and economic objectives are pursued (mainframe computers can perform complex on-line/off-line optimization). The advantage to distributed control is that it makes effe ve use of current technology and provides a framework within which control and optimization developments can be implemented. These developments probably will include better simulation and optimization routines that will help to assess the current state of the process plant and to suggest improvements. 

It is obvious that the most important requirements for safe machine operation as a mechatronic system are placed at its design stage, at which all the risk analyses must be carried out and all the available technical measures must be implemented based on the outcomes. The goal herein must be the elimination or minimization of risk. The requirements also affect the selection of effective methods for risk estimation for all the parts of a machine or a complex machinery system, including its control system, at all the stages of a machine s technological lifespan. 

Monitoring of systems feedback provides an opportunity for error detection and recovery when there is a mismatch between detected and observed outcome of an action. Human errors are not easily detected in complex systems. There may be a significant time lag between action and observed effects that makes detection difficult. The effects of human actions may be masked by actions taken by the technical control system. Biased error attribution on the part of the operator may also impede error recovery. Co-workers and supervisors are important resources for error recovery in this context. There are, however, some important preconditions for colleagues and supervisors to be able to contribute. They must co-operate closely with the erring operator to be able to observe performance and distinguish between erroneous and correct acts. There must also be a climate of trust and willingness to correct each other s behaviour. 

The sixth paper proposes a mathematical model of the computer-aided design of technical systems, based on notions of increasing sequence of macromodels, block frontal algorithms in the hypermatrix algebra, and a database approach. The next paper focuses on solid modeling, namely on using curves and surfaces with tension control to build complex surface models with geometric discontinuities. 

The processes of cathodic protection can be scientifically explained far more concisely than many other protective systems. Corrosion of metals in aqueous solutions or in the soil is principally an electrolytic process controlled by an electric tension, i.e., the potential of a metal in an electrolytic solution. According to the laws of electrochemistry, the reaction tendency and the rate of reaction will decrease with reducing potential. Although these relationships have been known for more than a century and although cathodic protection has been practiced in isolated cases for a long time, it required an extended period for its technical application on a wider scale. This may have been because cathodic protection used to appear curious and strange, and the electrical engineering requirements hindered its practical application. The practice of cathodic protection is indeed more complex than its theoretical base. 

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