a 3 user ajustable process control system

... COMMUNICATIONS IN A PROCESS CONTROL SYSTEM by GR MacKenzie, AEG Communication has become a major part of any process control automation system Today PLC communication is as much for data acquisition ... than one bit per baud Baseband and broadband The principle characteristics of base-band and broadband systems are listed in Table BASEBAND Digital signalling Entire bandwidth consumed By signal ... in automation systems today, have at least one PS 232 (serial) interface as a standard RS 232 , however, has some limitations Distance, a maximum of 50 ft by definition (without modems) is a major...

Ngày tải lên: 25/12/2013, 08:50

... pair cable and standard connectors A few European PLC manufacturers immediately adopted this standard This Bit Bus, however, was also seen to have a major shortfall, in that it was based on a ... performance, and is generally cheaper The maximum transmission time for any network configuration can be calculated A classic rule for any PLC application is that repeatability is more important than ... the control is a master-slave type control This works well, as if either user fails, no communication can take place anyway In a bus configuration, however, this is not always the case For installations...

Ngày tải lên: 25/01/2014, 05:20

... Absorption and Humidification 32 6 Evaporation and Crystallization 33 2 Extraction and Extractive Distillation 33 8 Drying Operations 34 3 Summary 34 6 References 34 7 Problems 34 7 Appendix: Answers to ... of mass or energy may change In fluid systems, tanks have capacity to hold liquid or gas In electrical systems, capacitors are used to store nominal amounts of charge Heat capacity is a factor ... sustain oscillations A Two-capacity Process Having established the ease with which a single-capacity process may be controlled, the complications involved in adding a second capacity may be evaluated...

Ngày tải lên: 01/04/2014, 11:09

... famous iris databases, that is, CASIA-IrisV3, Bath, and Ubiris CASIA-IrisV3 includes three subsets which are labeled as CASIA-IrisV3-Interval, CASIA-IrisV3-Lamp, and CASIA-IrisV3-Twins CASIA-IrisV3 ... Unlike the CASIA-IrisV3 database, it includes EURASIP Journal on Advances in Signal Processing (a) (b) (c) Figure 7: Some samples taken from (a) CASIA-IrisV3 database, (b) Bath database, and (c) ... with (a) Boles and Boashash [10], Daugman [5], Ma et al [7], and (b) Monro et al [15], Halligswroth et al [27] methods using CASIA-IrisV3 iris database 95 90 0.01 0.1 False acceptance rate (%)...

Ngày tải lên: 21/06/2014, 22:20

... Absorption and Humidification 32 6 Evaporation and Crystallization 33 2 Extraction and Extractive Distillation 33 8 Drying Operations 34 3 Summary 34 6 References 34 7 Problems 34 7 Appendix: Answers to ... of mass or energy may change In fluid systems, tanks have capacity to hold liquid or gas In electrical systems, capacitors are used to store nominal amounts of charge Heat capacity is a factor ... sustain oscillations A Two-capacity Process Having established the ease with which a single-capacity process may be controlled, the complications involved in adding a second capacity may be evaluated...

Ngày tải lên: 27/06/2014, 05:20

... Absorption and Humidification 32 6 Evaporation and Crystallization 33 2 Extraction and Extractive Distillation 33 8 Drying Operations 34 3 Summary 34 6 References 34 7 Problems 34 7 Appendix: Answers to ... of mass or energy may change In fluid systems, tanks have capacity to hold liquid or gas In electrical systems, capacitors are used to store nominal amounts of charge Heat capacity is a factor ... sustain oscillations A Two-capacity Process Having established the ease with which a single-capacity process may be controlled, the complications involved in adding a second capacity may be evaluated...

Ngày tải lên: 27/06/2014, 08:20

... respect, and compensation improperly applied can aggravate the situation The steady-state relationships that prevail among manipulated, load, and cont,roIled variables take on paramount importance ... sustain oscillations A Two-capacity Process Having established the ease with which a single-capacity process may be controlled, the complications involved in adding a second capacity may be evaluated ... -2an T n+m 70 (2 .3) This indicates t,hat a large number n of isolated lags approaches the same phase charactcrist,ic as dead time of value m The same is not, true in t,he interacting case, because...

Ngày tải lên: 12/08/2014, 16:21

... dynamic gain is invariant Steady-state gain, as calculated above, is only meaningful at the rated flow F.) Dimensional gain of the composition process can always be found by writing a material ... applications Practical Considerations Pure dead time cannot be generated by analog means, therefore a dead-time complementary analog controller will never be available Dead time can be generated ... the estimate of the natural period and proportional band in Prob 3. 1 if the dynamic elements were all assumed to be dead time rather than capacities? Is this a valid approximation? Why? 3. 3 Let...

Ngày tải lên: 12/08/2014, 16:21

... total flow was the primary manipulated variable Infinite Ratio Rangeability The range of adjustment available with standard ratio stations is typically 0 .3 to 3. 0 Using a single multiplier, a range ... a material balance can be enforced by flow controllers, temperature controllers are often used to manipulate a heat balance Careful control of heat balance is most important in a chemical reaction ... m normally greater and more rapid t’han load disturbances, taking advantage of the region of higher gain Load disturbances make their appearance as a slow departure of the controlled variable...

Ngày tải lên: 12/08/2014, 16:21

... which places a particular demand on the control system Like a manipulated variable, the load is flow or a function thereof In a mass transfer operation, the load is mass flow In a level -control ... measure the variable, place a value on it, and find out how to maximize (or minimize) it If the variable can be measured and an appropriate manipulated variable found, feedback optimizing control ... signals mentioned above permit many economic variables to be generated For example, the conversion in a reactor can be assimilated from a heat balance across it Yield can be calculated as the ratio...

Ngày tải lên: 12/08/2014, 16:21

... Adaptation An adaptive control system was defined as having the ability to change its parameters in accordance with the changing character of the process A feedforward control system, by itself, can only ... balances on the process, and the manipulated variables must therefore be accurately regulated flow rates An example is the balancing of firing rate vs thermal power that is being withdrawn as ... flow as shown in Fig 8.5 Two failings of the steady-state control calculation should be noted: Each load change is followed by a period of dynamic imbalance, which makes its appearance as a transient...

Ngày tải lên: 12/08/2014, 16:21

... sure, a certain amount of subcooling always takes place, in whatever area is not used for condensing The amount of subcooling varies FIG 9.7 The heat transfer area available for condensation can ... the system has not changed, the rate of heat transfer farther away from the burner tends to increase Safety dictates certain operating precautions for fuel-air controls A deficiency of air can allow ... Should the fuel be gas at a variable temperature or pressure, computation of mass flow may be warranted, particularly if these variations are frequent or rapid STEAM-PLANT CONTROL SYSTEMS In order...

Ngày tải lên: 12/08/2014, 16:21

... &reams in each of the above is eit’her pure, as the vapor from an evaporator, or in an equilibrium stat’e independent of material-balance considerat’ions Although materialbalance control can ... investigation of material-balance control Material-balance Control A certain amount of solvent is evaporated in each effect relative to its heat input; all the solids in the feed are discharged ... constant Similarly, a material balance may be drawn across the stage: A( xo - XI> = B(y, - yo) (12.27) Recognize that A and B are mass flow rates of the two solvents, and that x0 and yo are the...

Ngày tải lên: 12/08/2014, 16:21

... Mass transfer operations, 32 5 -32 6 Material balance, in absorption, 32 8 in crystallizers, 33 7, 33 8 in distillation, batch, 31 9 -32 1 continuous, 289-292, 30 7, 30 8 in evaporators, 33 3 -33 5 in extractors, ... Distillation, 288 -32 3 analyzers in, 30 3 -30 5 azeotropic, 34 0 -34 2 batch, 31 9 -32 3 with constant distillate quality, 32 1, 32 2 with constant distillate rate, 32 0, 32 1 with optimum distillate rate, 32 2 ,32 3 ... compensation in, 31 4 -31 6 entrainer in, 34 1, 34 2 extractive, 34 2, 34 3 feedback control of, 295 -30 6 feedforward control of, 30 7 -31 9 heat balance in, 296 -30 2 interaction in, 296-298, 30 5, 30 6 lead-lag...

Ngày tải lên: 12/08/2014, 16:21

... statistical control charts for monitoring process variance changes Johnson and Leone (196 2a, 1962b) and Page (19 63) later proposed CUSUM charts based on sample variance and sample range As an alternative, ... etc A QC can be mathematically defined as a random variable, which is a function that takes values from a population or distribution Denote a QC as random variable x If a population Ω only contains ... variation change Notice that SPC charts are designed to detect assignable causes of variation as indicated by mean or standard deviation shifts and at the same time tolerate the chance variation as shown...

Ngày tải lên: 23/01/2014, 01:20

... batch-type simulation sessions It is imperative that a dynamic simulation is ‘packaged’ in a way that makes it easy to use and learn, yet still be applicable to a broad range of applications and ... concepts as fundamentals of chemical engineering For undergraduate programs looking to transition away from the traditional mathematical-based approach to a more applied, hands-on approach, this ... of an actual plant Dynamic simulation allows for the comparison of several candidate control strategies and assesses the propagation of variation through a process/ plant In other words, dynamic...

Ngày tải lên: 01/01/2014, 17:44

... Cataloguing in Publication Data Control systems design : a new framework Automatic control I Zakian, Vladimir 629.8 ISBN 185 233 9 136 Library of Congress Cataloging-in-Publication Data Control systems ... Chulalongkorn University Bangkok 1 033 0 Thailand e-mail: suchin .a@ chula.ac.th Tadashi Ishihara Faculty of Science and Technology Fukushima University Kanayagawa 1, Fukushima, 960-1296 Japan e-mail: ... but has been given various, somewhat arbitrary, mathematical interpretations, each leading to a separate branch of mainstream control theory and design Although sensitivity is a way of quantifying...

Ngày tải lên: 01/01/2014, 18:49

Ngày tải lên: 26/01/2014, 07:20