Communication and Control

The second major pair of ideas in systems theory is communication and control. An example of regulatory or control action is the imposition of constraints upon the 

This statement is somewhat of an oversimplification, because the reliability of a system component can, under some conditions (e.g., magnetic interference or excessive heat) be impacted by its environment. The basic reliability of the component, however, can be defined and measured in isolation, whereas the safety of an individual component is undefined except in a specific environment. 

The link between control mechanisms studied in natural systems and those engineered in man-made systems was provided by a part of systems theory known as cybernetics. Checkland writes  

Control is always associated with the imposition of constraints, and an account of a control process necessarily requires our taking into account at least two hierarchical levels. At a given level, it is often possible to describe the level by writing dynamical equations, on the assumption that one particle is representative of the collection and that the forces at other levels do not interfere. But any description of a control process entails an upper level imposing constraints upon the lower. The upper level is a source of an alternative (simpler) description of the lower level in terms of specific functions that are emergent as a result of the imposition of constraints [36, p. 87]. 

Note Checkland s statement about control always being associated with the imposition of constraints. Imposing safety constraints plays a fundamental role in the approach to safety presented in this book. The limited focus on avoiding failures, which is common in safety engineering today, is replaced by the larger concept of imposing constraints on system behavior to avoid unsafe events or conditions, that is, hazards. 

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Drug adverse events will always remain part of modern medicine and the potential for another thalidomide disaster cannot be totally dismissed. The prevention of a future disaster lies, not in simply increasing the number of regulatory hurdles but in the ability to communicate and control unexpected events and where necessary make rapid withdrawal from the market. 

The discovery of a multitude of naturally occurring, bioactive peptides has generated a rich source of pharmacophores from which medicinal chemists are developing new useful therapeutic drugs. After binding to an enzyme, or a membrane receptor, peptide-based inhibitors, neurotransmitters, immunomodulators, and hormones influence cell-to-cell communications and control a variety of vital functions such as metabolism, immune defense, digestion, respiration, sensitivity to pain, reproduction, and behavior. 

Frederick, D. K. and Carlson, A. B. Linear Systems in Communication and Control Wiley New York (1971). 

In contrast to the endocrine system that achieves long-term control via chemical (hormonal) mechanisms, the nervous system relies on more rapid mechanisms of chemical and electrical transmission to propagate signals and commands. The rapid conduction of impulses is essential in allowing the nervous system to mediate shortterm and near immediate communication and control between various body systems. 

J. M. Mendel, Lessons in Estimation Theory for Signal Processing, Communications, and Control, Prentice-Hall, Englewood Cliffs, NJ, 1995. 

For many applications, adhesives are formulated and tailored around specific products and environments. Among these are the ground communication and control equipment for the military that must withstand a wide spectrum of harsh terrestrial climates in addition to high levels of shock and vibration. Spacecraft electronics will be subjected to high vacuum, low temperatures, and particle bombardment from both radioactive and physical particles. Other specific applications include memory modules, automotive, flat-panel displays, optoelectronics, LEDs, MEMS, and EMI shielding. 

It is clear that such inherent rhythms are important in endocrine communication and control, suggesting that its physiologic organization is based not only on the structural components of the system but also on the dynamics of their interactions. The rhythmic, pulsatile nature of release of many hormones is a... 

The MCU is the communication and control hub for the FES-BPB System. The MCU transmits commands to and receives data from aU the BPBs and the recharging subsystem. There are two versions contemplated for the MCU packaging (1) an external MCU, which will be outside the body and have a few controls accessible to the patient and (2) an implantable MCU, which will be implanted in a convenient location in the body. The implantable MCU version wiU have a small patient control unit (PCU). 

The endocrine (hormonal) system is a network of glands and receptors that function to regulate a number of key body-functions, like growth, development, and maturation, as well as the operation of various organs in the bodies of vertebrates. In short, the endocrine system provides the key communication and control link between the nervous system and all body functions, through the secretion of hormones. 

D.R. Kipke, R.J. Vetter, J.C. Williams, and J.F. Hetke, Silicon-substrate intracortical microelectrode arrays for long-term recording of neuronal spike activity in cerebral cortex. In 2nd International Meeting on the Brain-Computer Interfaces for Communication and Control. Rensselaerville, Institute of Electrical and Electronics Engineers Inc., New York, 2002. 

Biosignal-ocular- gaze EOG Enables users to communicate and control with eye direction... 

Biosignal-brain EEG Enables communication and control with brain signal patterns. Used in the expanding field of brain-computer interfaces... 

Wolpaw, J., Birbaumer, N., McFarland, D., Pfurtscheller, G., and Vaughan, T., 2002. Brain-computer interfaces for communication and control. Clinical Neurophysiology, 113(6), 767-791. 

The foundation of systems theory rests on two pairs of ideas (1) emergence and hierarchy and (2) communication and control [36],... 

Several definitions have been put forward over the last 40 years but what is known as modern logistics is generally viewed as a business planning framework for the management of material, service, information and capital flows. It includes the increasingly complex information, communication and control systems required in today s business environment. It fits into the supply chain as defined by Mentzer et al. as a set of three or more entities (organizations or individuals) directly involved in the upstream and downstream flows of products, services, finances andjor information from a source to a customer (see Figure 4.1). ... 

Are there certain jobs for each craft that should not be attempted by a single person How are they communicated and controlled ... 

Finally, improved communications and control mechanisms are needed. For example, w neural networks could be used to train optic flow sensor controls to react appropriately to changes in light intensity, diffuse objects (such as fog), and low contrast obstacles (such as a white waU) [10]. Beyond the control of single microrotorcrafts, strategies should also be developed to control communications and reactions for groups of these vehicles. 

The excellent electrical insulation properties of PE and its good moisture resistance make it well suited for wire and cable coatings. Uses include power, communications, and control applications. Other major applications of PE include pipes such as domestic water and gas piping, agricultural piping, and ink tubes for ballpoint pens. PE is also used as a filament on rope, fishing nets, and fabrics. 

Smith RG (1980) The contract net protocol high-level communication and control in a distributed problem solver. IEEE Trans Comput 29(12) 1104-1113... 

Mendel, J. Least-squares estimation Singular-value decomposition. In Lessons in Estimation Theory for Sigruil Processing, Communications, and Control Prentice Hall New Jersey, 1995 44—57. 

Electronic options for Li-ion batteries include the basic functions of monitoring, measuring, calculating, communicating, and controlling the cells in a battery pack. In practice, the battery pack may vary in size both physically and by the number of cells, but each will utilize some of the same electronic functions required to protect the cells and/or ensure their performance in the device. 

The basic functions of monitoring, measuring, calculating, communicating and controlling are a representation of electronic options to enhance the safety and maintain the performance of a collection of cells in a battery pack. Although these functions can he applied to any battery, they are not all required in any particular battery-powered device (Figure 16.1). 

Another point of consideration as a battery pack adds more functionality, such as the calculating, communicating and controlling functions, is the ability to communicate after an abusive event that has activated the controlling interruption of the current. 

As with smaller, multicell devices like tablets, net-books, or subnotebooks, the battery may contain functionality that includes all monitoring, measuring, calculating, communicating and controlling components. Advanced features including black-box recording of abuse or failure conditions as well as authentication to prevent after-market or counterfeit batteries may also be included. 

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