System outputs

Cogeneration systems will not match the varying power and heat demands at all times for most applications. Thus, an industrial cogeneration systems output frequently must be supplemented by the separate on-site generation of heat or the purchase of utility-supplied elec tric power. If the on-site electric power demand is relatively low, an alternative option is to match the cogeneration system to the heat load and contract for the sale of excess electricity to the local utihty grid. 

In control engineering, the way in which the system outputs respond in changes to the system inputs (i.e. the system response) is very important. The control system design engineer will attempt to evaluate the system response by determining a mathematical model for the system. Knowledge of the system inputs, together with the mathematical model, will allow the system outputs to be calculated. 

If the dynamic behaviour of a physical system can be represented by an equation, or a set of equations, this is referred to as the mathematical model of the system. Such models can be constructed from knowledge of the physical characteristics of the system, i.e. mass for a mechanical system or resistance for an electrical system. Alternatively, a mathematical model may be determined by experimentation, by measuring how the system output responds to known inputs. 

Frequeney domain analysis is eoneerned with the ealeulation or measurement of the steady-state system output when responding to a eonstant amplitude, variable frequeney sinusoidal input. Steady-state errors, in terms of amplitude and phase relate direetly to the dynamie eharaeteristies, i.e. the transfer funetion, of the system. 

Works in diserete time - only snap-shots of the system output through the A/D eonverter are available. Henee, to ensure that all relevant data is available, the frequeney of sampling is very important. 

Tesla arrived in New York in 1884 and was hired by Edison. Edison understood Tesla s ability but remained unconvinced by his new employee s insistence on the use of alternating current for electrical power transmission. Nevertheless, Tesla accepted his assignment to work on improving Edison s direct-current method, which was then in use. Working long hours Tesla increased the system output and asked Edison for a 50,000 bonus, which Tesla understood he was to receive. Edison refused, claiming that the bonus had only been a joke. Tesla quit Edison s employ, and thereafter relations were strained between the two men. 

Feedback control can never be perfect as it only reacts to the disturbances which are already measured in the system output. The feed-forward method tries to eliminate this drawback by an alternative approach. Instead of using the process output, the measured variable is taken as the measured inlet disturbances and its effect on the process is anticipated via the use of a model. The action is taken on the manipulated variable using the model to relate the measured variable at the inlet, the manipulated variable and the process output. The success of this control strategy depends largely on the accuracy of the model prediction, which is often imperfect as models can rarely predict the... 

There are no standard notations. We could have used Y in place of C for system output. Or replaced Ga by Gv for valve (Gf is also used), GL and L by Gd and D for disturbance, and Gm by Gt for transducer. We have selected P to denote controller output, more or less for pneumatic. 

Regulator problems Consider changes in disturbance with a fixed set point (R = 0) C = G oacjL. The goal is to reject disturbances, i.e., keep the system output at its desired value in spite of load changes. Ideally, we would like to have C = 0, i.e., perfect disturbance rejection. 

Errors in system output measurements can produce calibration errors because the model user will be attempting to calibrate against inaccurate or missing data. Errors associated with system outputs are discussed below. 

The environmental compartments are represented by boxes and the concentration of a chemical in these boxes is affected by processes that cause mass flows of the chemical to and from the boxes. The chemical can be input into a box from outside the system, output from a box to outside the system, or transported by means of advective or diffusive processes to and from other boxes. A mass balance equation can be written for each of the boxes representing the mass flow of the chemical. Generally, the magnitude of these mass flows depends on the concentration of the chemical in the boxes. If mathematical expressions which relate the mass flows to the concentrations are available, the set of mass balance equations (one for... 

Control system output is the actual response obtained from a control system. In the example above, the temperature dropping to a preset value on the thermostat causes the furnace to turn on, providing heat to raise the temperature of the house. 

Control system output is the actual response obtained from a control system. 

Real-time parameters Alarm management Polarisation curves Data Analysis Intelligent System Output... 

In this setting, the exosystem may be also nonlinear and it is supposed that it does not depend on p, which is often verified in practical problems since the exosystem models the reference and disturbance signals affecting the plant. Moreover, the third nonlinear function in (31) describes the output tracking error e G R, which, in many cases, is given as a difference between the system output /i(x,p) and the reference signal, described by r uj), namely... 

Lemma 1. Let y = St the system output. Then, the AD model (2) has a well-defined relative degree r = 1 under NOG, when the dilution rate D is used as the control input. 

We will define a system output as a quantity or quality that might be influenced by the system. 

Again, the definition of system output is purposefully broad. It could have been made narrower to include only those quantities and qualities that are influenced by the system. However, to do so presupposes a more complete knowledge of the system than is usually possessed at the beginning of a research and development project. System outputs that are influenced by the system are called responses. 

System outputs can include such quantities and qualities as yield, color, cost of raw materials, and public acceptance of a product... 

Four types of measurement scale can be used for assigning values to varying amounts of a property associated with a system input or system output [Summers, Peters, and Armstrong (1977)]. In order of increasing informing power, they are nominal, ordinal, interval, and ratio scales. The characteristics at determine a measurement scale s level of sophistication are name, order, distance, and origin. The characteristics of the four types of measurement scale are shown in Table 1.3. The nominal scale possesses only one of these characteristics the ratio scale possess all four characteristics. 

It is usually not possible or practical to control a given system input at an exact level in practice, most inputs are controlled around set levels within certain factor tolerances. Thus, controlled system inputs exhibit some variation. Variation is also observed in the levels of otherwise constant system outputs, either because of instabilities within the system itself (e.g., a system involving an inherently random process, such as nuclear decay) or because of the transformation of variations in the system inputs into variations of the system output (see Figures 2.17 and 2.18) or because of variations in an external measurement system that is used to measure the levels of the outputs. This latter source of apparent system variation also applies to measured values of system inputs. 

To simplify the presentation of this chapter, we will look only at variation in the level of measured system outputs, but the same approach can also be applied to variation in the level of measured system inputs. We will assume that all controllable inputs (known and unknown) are fixed at some specified level (see Figure 3.1). Any variation in the output from the system will be assumed to be caused by variation in the uncontrolled inputs (known and unknown) or by small, unavoidable variations about the set levels of the controlled inputs [Davies (1956)]. 

A two-factor response surface is the graph of a system output or objective function plotted against the system s two inputs. It is assumed that all other controllable factors are held constant, each at a specified level. Again, it is important that this assumption be true otherwise, as will be seen in Section 12.2, the response surface might appear to change shape or to be excessively noisy. 

JLosbash Why don t you hke the idea that the period in the animal is an integrated systems output phenomenon When you start taking the pieces apart, especially under mutant conditions, you get less robust or less well contained periods and amplitudes. 

Transfer functions, when fired, create a transformation process. A transformation process in a project is made up of methods, steps, tasks, and various algorithms and processes that acquire and manipulate data and then turn it into system output(s). Note that the input data can describe material, human knowledge, technological standing, fiscal information, and others. 

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