Understanding Systems: Concepts, Engineering Applications, and Interconnections, Schemes and Mind Maps of Industrial Engineering

Download Understanding Systems: Concepts, Engineering Applications, and Interconnections and more Schemes and Mind Maps Industrial Engineering in PDF only on Docsity! UNIT 2 SYSTEMS CONCEPTS AND INDUSTRIAL ENGINEERING Structure 2.1 Introduction Objectives 2.2 Engineering and Systems 2.2.1 Uses and Meanings of the Word 'System' 2.2.2 Engineered Systems 2.3 The Whole and the Parts : System and Components 2.4 System and Environment : Inputs and Outputs 2.4.1 System and Environment 2.4.2 Inputs and Outputs : Block Diagrams 2.4.3 Interconnection Diagrams 2.4.4 The Whole and the Parts - Invariance Principles 2.5 Manual and Automatic Feedback 2.6 System Performance Specifications 2.7 System Analysis and Design 2.8 Man-made Systems and "Natural" Systems 2.9 System Approach in Industrial Engineering 2.10 Summary 2.1 1 Key Words 2.12 Answers to SAQs 2.1 INTRODUCTION Industrial engineering adopts a system approach in analysing and solving the problems in an organisation. An industrial engineer does not analyse the problem in isolation. He takes an integrated view of the problem. He considers all the constraints imposed on the system from both inside and outside the system. In system approach all the factors which influence the system are also being considered. In this unit, you will learn about some basic concepts of systems theory. The concept of a system has arisen out of the practical human activity of 'putting things together' to achieve some goal. Although, basically, the term 'system' can only be applied to something engineered by man, you will see that some naturally occurring things can also be viewed as systems. A system is basically a 'whole' obtained by interconnecting appropriately 'parts' to achieve a desired behaviour. You will learn that system behaviouir is described in terms of physical variables some of which are 'inputs' and some others, 'outputs'. Certain 'invariance principles' must hold in order for this 'parts-whole' viewpoint to be useful. Feedback, or monitoring of the behaviour of a system, is most often used, and it may be manual or automatic. You will see that the design of a system usually requires the carrying out analysis of system behaviour. We conclude with some observations on the study of some naturally occurring things as systems. Objectives After studying this unit, you should be able to decide whether systems concepts can be used in a given problem situation, Industrial Engineering specify the component relations and interconnection relations as given problem for which the systems approach can be used, identify all the physical variables, including input and output variables, I I decide whether feedback should be used and if so, how it should be achieved, I draw the schematic diagram and interconnection diagram, and 1 formulate the system goal or design objective in terms of the system behaviour. 2.2 ENGINEERING AND SYSTEMS - I 2.2.1 Uses and Meanings of the Word 'System' In ordinary conversation, we quite often use the work 'System'. (a) Thus, we talk about 'the system of Government' or 'the political system' of a country, the system of 'education' or 'educational system'; 'the legal system'; 'the health or medical system'; 'the economic or financial system'; 'the system of arranged marriages'; and even 'the dowry system' and the 'caste system'. All these systems may be said to be examples of 'social systems'. First and foremost, a social system involves people - they could be people living in a village, town, city, region, state, country, or even all the people living on this earth - the entire mankind. Secondly, a social system concerns the social behaviour of these people, i.e. their behaviours in so far as these effect one another. Thirdly, the work 'system' highlights the fact that the behaviour of individuals constituting the 'system' are expected to conform to some rules and mutual relations or roles. Very often, these rules are make explicit, as for example, 'the constitution of a country', the laws of country', 'the Rules and Regulations of a University', and so on. (b) We also talk of 'the transportation system' - such as the 'railway network', 'the communication system', 'the postal system', 'the defence system', 'the irrigation system', 'the electrical power or energy system', 'the manufacturing or industrial system', etc. These would all be said to be examples of 'engineering systems'. Of course, all the engineering systems mentioned above involve people, but they also involve a significant amount of material things, of infrastructure, of hardware. They all have to be designed and built - 'engineered' (social systems may also require some infrastructure system of Government. But social behaviour is the most important thing in a social system). We could - and should - regard even a house or a building as an example of an engineered-system. In general, one can recognise three phases, stages or steps of an engineering activity -the design or planning phase, the construction or execution phase, and lastly, the utilisation phase. Of course. an engineering system that has been completed and commissioned, i.e. put to use, may be subsequently modified, updated, modernised, expanded - or even scrapped or written-off (we do often talk about the limited lives of engineering systems). (c) have also been told about some other systems in your school education -the respiratory systeln of the human (or animal) body and of plants, the circulatory systeln of animals and plants, the digestive system of animals (one could talk about digestive sensations?). These are all examples of 'biological systems'; they are systems 'inside' a living being. It is tempting to ask - are these biological systems 'engineered'? Have they been planned? How are they constructed? Of course, we all know well that they all have only a limited life. 2.4 SYSTEM AND ENVIRONMENT : INPUTS Systems Concepts and Industrial Engineering AND OUTPUTS 2.4.1 System and Environment In a broad sense, all systems, whether engineered (buildings, lathes, electric motors, chemical plants), or natural (human beings, plants, human society), are a part of Nature, exist in nature, or are natural. They are all subject to the influences of the other components of this big and complex system that we call Nature. Thus, a building is subject to various environmental influences such as the weather (heat and cold, humidity and rain, wind and - yes - earthquakes), and it has to be designed taking into account these influences. But these influences are beyond the control, or the will, of the designer. Sometimes they can be measured as and when they occur. Sometimes they can be anticipated or estimated. In system theory, such influences are known as disturbances or disturbance inputs to the system. Of course, the environment is not all disturbances. It does provide support or sustenance to the system. Thus, the building is indeed supported by the foundation below - soil or rock - but there can be some uncertainty about such support; for example, the soil may sink, the rock may crack, or there could be tremors. What would be the environment for a system consisting of, say, the ceiling fan in your room, or the electric motor and water pump for the storage tank of your building. Here, the environment consists of the electric supply to your house or building, and the water supply to your building. What would be some of the disturbances, which your system will have to face up to? Changes in the power supply voltage - and even its failure - could be one disturbances. Changes in the water supply rate - and its being shut off altogether - could be another. Then, the ceiling fan (motor) or the pump set motor could get over heated. 2.4.2 Inputs and Outputs : Block Diagrams Unlike the disturbances to a system which are not under the control of the system designer or system user, there are some other things associated with a system which are under the user's control. Thus, usually the speed of the ceiling fan, or of the pump motor can be controlled, or changed at will - to some extent, of course. The ceiling fan usually has a speed regulator going with it; by turning that knob or dial of the regulator, one can vary the speed - within limits, from a minimum, low speed to a maximum or full speed. Similarly, the pump motor could be made to supply more or less power to the pump. Such actions are referred to as the inputs or input actions to the system, and they are associated with physical variables or signals which can be measured and are known as the input variables. Thus, the ceiling fan motor has an input variable, associated with it, namely, the voltage across it, which can be measured by a voltmeter. This input voltage is changed by changing the position of the knob of the speed regulator, so the position of this knob could be regarded as an input to the speed regulator regarded as a sub-system. This example also illustrates the general situation that the system has some other physical variables also associated with it; there are its output or output variables. The output variable of the ceiling fan would usually be its sqpeed, although the fan motor also produces heat (the rheostat type regulator certainly does!). The output variable of the regulator wodd be the voltage 'fed' to the fan motor. The situation can be pictorially represented by means of a system diagram, which is also called a block diagram, because it consists of a number of 'blocks'. In the Figure 2.1, we have shown two blocks, these are the two sub-systems of the system we are interested in. Of course, the electric wiring and the mechanical mounting of the regulator and fan assembly, as well as the entire power supply system are important components of the system, but for studying a specific aspect of the system, namely, speed control of the fan, it is necessary and sufficient to think of the above two blocks. Industrial Engineering Power Supply Voltage Figure 2.1 . Now, the block marked 'Fan Motor' has two variables associated with it, shown by 'arrows' attached to it. The 'incoming' arrow usually placed on the left-hand side of the block, represents the input variable, in this case, the voltage across the motor winding. Knob Position The 'outgoing' arrow, usually placed on the right-hand side of the block, represents the output variable, in this case, the speed of the motor, or of the fan blades, or indirectly, the ventilation and cooling that the fan provides. Note that the fan speed does not physically 'come out' of the fan, as water would come out of a container, nor is the voltage poured into the motor. It is only metapherically that we talk about input and output. But then what is the difference between the two? The difference is that the input variable is usually under our direct control, whereas the output variable is not under our direct control, but is put under indirect control by the use of a device such as a fan motor (Direct control of the fan speed in case the electric failed could be achieved by asking somebody to turn the fan by hand!). We desire that it should be possible to change the fan speed, and we achieve this possibility by building a special kind of device - the fan motor - and providing the possibility for something else to be changed, namely, the voltage to the motor. The input variable is also known as the command or control variable, and the output variable as the controlled or manipulated variable. Voltage to Motor Fan Speed Regulator Fan Speed Voltage to Motor . b Figure 2.2 But then, how do we provide for the possibility of varying the voltage to the fan motor? By designing another sub-system, namely, the speed regulator. Let us consider the speed regulator by itself. Fan Motor Fan Motor Power Supply Voltage Fan Speed b + Voltage to Position 4 Fan Speed 1 Motor + Regulator Figure 2.3 Notice that the block representing this sub-system has two incoming arrows, because it has two inputs. One of them is the environmental input which can also act as a disturbance; this is the power supply voltage. It is not under our control, usually we have to take it or leave it. If there is a power failure, our fan won't work - unless we have a stand-by power supply. In fact, it is because the power supply voltage cannot be varied at will - it is not under our control, it is not a control variable - that we invent the fan speed regulator! The other input to the block is our control input, namely, the position of the knob. This can be varied at will to a limited extent - unless it gets jammed! The block has one outgoing arrow, representing the output variable, the voltage to motor, which is thus, indirectly controlled or manipulated - which it turn, directly controls or manipulates the fan speed. You will see that the block diagram of Figure 2.1 can be obtained by combining the two Systems Concepts and block diagrams of Figures 2.2 and 2.3, so that the output of the fan speed regulator . Industrial Engineering becomes the input to the fan motor, this variable being indicated by a single arrow going from one block to the other in Figure 2.1. In practical or 'hardware' terms, this involves joining the 'terminals' of the fan regulator to the terminals of the fan motor. 2.4.3 Interconnection Diagrams A block diagram such as the one in Figure 2.1, which shows the various input and output variables for various sub-blocks comprising it, is different from an interconnection diagram or schematic diagram which shows the interconnections between the various components of a system, without usually showing any system variable at all. Figure 2.4 show's such a diagram for a simple electrical network; it is therefore, also known as a network diagram. Note that the diagram uses some standard symbols to represent the various components or elements, and the 'parameter values' of the components may also be specified. Thus, in the network shown in Figure 2.4, there are three resistors, labeled as R,, R3 and R5 (R for resistor), and the values of their resistances are also indicated (k R is to be read as kilo-ohms). The symbol commonly used to represent a resistor is a 'jagged' line. here are two capacitors, labeled as C2 and Cq (C for capacitor), and pF is read as 'micro-farads'. The symbol for a capacitor is made up of two parallel lines (which reminds one of the two parallel 'plates' of a special type of capacitor), with two attached lines, indicating the two leads wires. The network - sometimes also called an electric circuit - has one more component of a different type, namely, a dc voltage source, indicated by the symbol E6, with a value of 1.5 volts. In hardware form, it is usually a dry cell. Its symbol consists of two unequal parallel lines, the longer line indicating the 'positive' terminal, also marked with a '+' sign,and the shorter line the 'negative' terminal marked with a '-' sign. How does the network diagram represent the interconnections of these 6 components? By a set of lines together, as shown by the small thick circles marked a, b, c and d. b d Figure 2.5 Each of these indicates that corresponding lead wires from several components are to be connected together. Sometimes, they are just twisted together, or inserted together into a binding post, but more often, they may be soldered together. They are also known as the junction points or interconnection points. Thus, the junction point indicates that the lead wire from the positive terminal of the cell Eg, one of the lead wires of the resistor R1 and one of the lead wires of the capacitor C2 are to be connected together. Industrial Engineering may be soldered together. In fact, one simplifies Figure 2.7 by dropping out the boxes and using numerical labels along side the several lines of the figure. Figure 2.8 which is the result is usually called the system (inter-connection) graph. a Figure 2.8 Now, the principle of invariance of inter-connection behaviour says that some inter-connection relations hold between the various physical variables of the devices which depend only on, and so, can be written down or formulated from the system inter-connection graph. In our circuit example, in order to associate definite physical variables (in this case, a voltage and a current) with each of the two-terminal devices, we have to say how certain measuring instruments (in this case, a voltmeter and an ammeter) should be connected with each of the devices. This is conventionally done by putting 'arrow heads' on the interconnecting lines of Figure 2.8, giving Figure 2.9 below which is usually called the directed or oriented system graph (Figure 2.8 will, therefore, be said to be an undirected system graph). a Figure 2.9 Once the directed system graph is given, the principle of invariance of inter-connection behaviour as applied to (or rather, as it holds in the case) electric circuits say that certain definite relations will hold between the physical variables of the various devices irrespective of what, these (two-terminal electric) devices are. Thus, device 1, no matter what it is, has an associated voltage variable v , and a current variable i l , similarly, 2 is associated with v2 and i2; and so on. Now, one principle of invariance of inter-connection behaviour, known as Kirchhoff s Current Law. Kirchhoff s Current Law Kirchhoff was a German physicist of the ninteenth century - says that because at junction point or node a, the three devices 1,2 and 6 are connected together and because the arrowheads (which stand for the manner in which ammeters might be connected to read off currents i , , i2 and i6) stand in particular way in relation to the node a, thus, the arrows on all the three edges 1 ,2 and 6 point away from the node a, the following relation or equation, known as a Kirchhoff's Current Equation holds : System Cowepta and Industrial Engineering Three more such relations can be written down, one for each of the remaining nodes, h, c, d; these are : (for node b) -i , +i3 +i4 = O . (for node c) -i2 - i 3 +i5 = O , (for node d) - i 4 - i5 -i6 = O . Similarly, another principle of invariance of inter-connection behaviour for electric circuits, known as Kirchhoff's Voltage Law, enables us to write down a set of relations or equations relating or connecting the six voltage variables. How are they written down from Figure 2.9? Well, suppose Figure 2.9 was not connected with any electric circuit, but was rather a map showing a number of cities (or places in a city) a, b, c and d and of roads 1,2,3,4, 5 and 6 interconnecting them. Then one could think of the following round trip or 'circuit' : start at a, go to h via 1, then to c via 3 and back to a via 2. This round trip in circuit theory is called a directed or oriented, closed path or loop or circuit -and once again, the manner in which the arrowheads are encountered on this trip enables us to write down the following Kirchhoff Voltage Equation : In fact, for each of the closed paths, we can write down one such equation. Notice that the equation does not depend on what kind of devices we encounter along the round trip, that is, on what sort of behaviour these devices have. Invariance Principles for Systems other than Electric Circuits We have considered the examples of an electric circuit in some detail because of the very obvious similarity among the various fingers associated with them. Thus Figure 2.4, which is the full circuit diagram, is seen to be similar to Figure 2.7 where the component information has been deleted, and to its further simplifications, namely Figures 2.8 and 2.9. Now, it is possible to draw directed system graphs for almost all engineering systems, but they are no longer so similar to the schematic diagram of the system, such as our simple pair of gears in Figure 2.6. But the two principles hold nevertheless. In particular, the interconnection equations can be written down from the schematic diagram without knowing anything about the components. Think of the diagram of a truss for a roof or a bridge, subjected to some load distribution, and the resulting tensions and compressions - stresses and strains - in the various members. SAQ 3 (a) Consider a human being, or even a plant. What would be the environment and the distributors for such a system? (b) What would be the inputs and outputs for civil engineering systems such as (i) a building, (ii) a bridge, and (iii) a road? (c) Could one think of concrete as a system consisting of cement, sand wid stone put together? Could one think of a RCC structure as a system, consisting of concrete and the reinforcement bars? (d) What could be regarded as the principles governing the interaction behaviour in the case of social systems? Industrial Engineering 2.5 MANUAL AND AUTOMATIC FEEDBACK Let us consider our fan regulator - ceiling fan system depicted in Figure 2.1 earlier. It is an example of a control system or controlled system. It is so called because the speed of the fan can be controlled, varied, chosen at will - within a limited range, of course. This is the main feature of control; control requires the possibility of choice. Imaging that one operated the fan directly on the domestic power supply. One would then have no control over its speed, that is, one would not choose the speed - from among a set of possible values - and then do something - turn the knob - to realise that choice or make it come true. (Usually, of course, there will be the minimum choice of having the fan turned on or off, that is, usually and on-off switch is provided, but what if the switch was jammed in one position?) So, imaging that we have the fan regulator installed and that the knob is not jammed. In the morning, a person mops the floor of the room and in order to make it become dry very quickly, he sets the knob to full speed, but before he can switch it off after the floor has become dried, he has to leave the room and he forgets all about it. Now, imagine that you enter the room after sometime; perhaps, it is your classroom that we are talking about. You find that the fan speed is too high and you don't want it that high, but rather you want it at the minimum speed, just enough to provide some ventilation. What do you do? Turn the knob to the minimum speed position. You have just managed a system with feedback - manual feedback, and a control action - change in the position of the knob -resulting from this feedback. Feedback means looking at what is actually going on, monitoring the behaviour of the system, and, if the behaviour is not satisfactory - the fan is going too fast -taking an appropriate control action, changing the appropriate control input to the system - the position of the knob. The feedback may be manual, that is, a human being watches the system and with his hands - 'manually' - changes the control input or, the feedback may be automatic, that is, provided by putting in some more components into the system to achieve the same purpose. We illustrate with a more practical example. Motor Speed Control Shown in Figure 2.10, the schematic diagram of a simple dc motor speed control system using feedback. Figure 2.10 Some of the symbols used in this figure are already familiar to you, namely, two cells and one resistor, but this resistor has an additional third terminal corresponding to a variable (sliding) control. M denotes the electric motor, T, a tachogenerator, K, a dc amplifier. The component, indicated by a curly line, connected to one of the cells denotes the field winding of the motor. Why do we say that this system uses feedback, or is a closed-cycle control system, or feedback-control system, and that too, automatic one? Because with the 'help' of the tachogenerator, the speed of the motor - and of the load and the tachogenerator, since they are all connected to one and the same shaft - is monitored, measures, and this monitoring is used to change the control action Apart from this ignorance about the components, there are uncertainties arising from Systems Concepts and ignorance about the environment of the system. These are known as disturbances or Industrial Engineering disturbance inputs to the system and have been already mentioned in Section 2.4.1 where the voltage of the electric power supply to the fan was indicated as a variable over . L 4 which we have no control, and so, which may - and usually does - keep changing. But one may know that it will not change too much. Although, by definition, the uncertainties associated with the system cannot be known, often they can be estimated, that is to say, some bonds on them can be used, whether it be in the form of tolerance on components, precision of measurement or changes in parameter values or environmental variables. SAQ 4 (a) Think of goal specification for (i) a building, (ii) a ceiling fan and (iii) speed regulator for a ceiling fan. Try to be as specific as you can, that is, make your specification as detailed as you can. (b) Think of component tolerances, precision of measurement and disturbance inputs in the context of civil engineering. 2.7 SYSTEM ANALYSIS AND DESIGN System design, of course, is an activity which is almost self-explanatory. It is the activity of building a new system, whether it be a building, a bridge, a television receiver, or a railway line. Actually, design is the phase that precedes the activity of construction but can be seen as a blueprint for construction. But, how does one design a system? In most cases, system design is based on past experience and is called for only when a new kind of system is to be made and not merely a copy of an existing system. Thus, a new model of television receiver will usually require designing, but once designed, one can go on manufacturing one receiver after another. Past experience about systems and their design is usually learnt in the form of system analysis. Thus, a beginning in electrical circuit (design will be asked to study a simple electric circuit such as the one we have already seen (Figure 2.4). What do we do when we analyse such a system? We learn about the nature of the components, the physical variables associated with them, the characteristics equations associated with them, the nature of the interconnections and the characteristics equations associated with the interconnections. Then we try to 'solve' the system; thus, for Figure 2.4, we may calculate the current in the resistor RI. Next, we try to get some more general information about such currents. We may try to find out what happens to the system behaviour (for example, the current R1) if a parameter value is changed (for example R1 is changed to 47 kQ), or if the structure of the system is changed. Only after such a study we are usually able to tackle a new design problem. Thus, suppose in Figure 2.4, R, was not specified but all other component values were specified, and R, was to be chosen so that R3 will have a current of 1 rnA - if that is possible. How will you find out? By trial say, choose R1 as 33 kQ and then finding out that it doesn't work? As you can see, design is an activity somewhat 'inverse' of analysis. In analysis, you are told everything about the system except its behaviour; you have to figure that out. In design, you are told about the behaviour that the system should have, what is wanted, what is desired, and you have to figure out which system will produce that desired behaviour. Of course, the two activities are inter-dependent and even cyclical as a pair. Thus, past experience - or study - enables you to purpose a simple design for achieving a given objective. You can analyse the chosen to see whether the objective is met. If not, you modify the design. The modification, too, may be based on past experience, but sometimes it requires a new invention! Industrial Engineering 2.8 MAN-MADE SYSTEMS AND "NATURAL" SYSTEMS We now come to a topic which is controversial but, to many people, exciting. We have already remarked that every system, even a man-made one, is basically, ultimately, finally - in fact, often initially - a natural one. But the distinction that one is making here is of a diffetent kind. Man-made or engineering systems are systems made or engineered by man. They require intervention by human beings; study, analysis, design, manufacture, assembly and so on. On the other hand, there are things which are not made by man in this sense but appear to be readymade. Rather, there are things which appear to be systems, or could be regarded as systems, profitably studied as systems and so on. The main example of this class of things are living beings, animal or plant. As we saw very early, we do talk about systems associated with living beings, and often about the living beings themselves as interconnections of, that is, system make up of these sub-systems. So, there are a number of interesting - and difficult! - questions that arise in connection with such systems. What is the nature of their 'components'? What are the device characteristics? What is the nature of the inter-connections and the laws of invariance about the interconnections? What kind of behaviour do these systems exhibit? Can we understand their behaviour by doing system analysis? Do they have a goal? Do they have a design? Lastly, how are they built? This is perhaps where they differ the most from engineered systems. Living beings grow; they are not built at once. Further, they propagate or give rise to other living beings. And finally, they evolve, that is, they change as they grow and propagate. 2.9 SYSTEM APPROACH IN INDUSTRIAL ENGINEERING If industry is compared to as a human being, the various systems in human body are quite analogous to the systems of an industry. Finance department is analogous to blood circulation system. Production system can be comparable to the hands and legs while skin can be considered as security department. The industrial engineering is supposed to be the most significant department in the industry is generally compared to as the brain that directs the methods of working to nervous systems for the human being. Industrial engineering system seen as a whole is in fact composed of many subsystems. The subsystems are mutually interactive and closely connected to one another with their relations. Therefore;whatever order in which these subsystems are studied, they should only be understood as systems simultaneous functioning with pace. The subsystems in the Industrial Engineering System are (a) Work Measurement (Time Study) Subsystem. (b) Method Study Subsystem. 2.9.1 Work Measurement (Time Study) Subsystem Any work can be split up into small activities called 'elemental movements' or simply 'elements' a d so we do. Then we eliminate all unnecessary elements. Then assign time to each elemental motion accurately with the help of stopwatch or standards. Classify and describe each elemental motion and its time carefully for future reference. Add an allowance to actual time to cover the time delays due to known or forecasted or unforeseen reasons. Standardize the tools and working conditions with more emphasis laid on method improvement. Industrial Engineers further encapsulated Taylor's study in three simple words viz. definite task, definite time and definite method. His study was directed towards the specialisation and standardisation. Time study has given rise to a firm scientific and calculated opinion on remuneration system too. The industrial engineer, after conducting time study prescribes the following : (a) Assign each worker a clearly defined tasWtarget with definite time. (task and time will be decided by the industrial engineer after necessary time study.) (b) Provide each worker with such standard conditions and appliances that will enable him to accomplish the task with certainty. (Industrial Engineer will prescribe the correct procedure and conditions applicable. Therefore, this subsystem is to be interfaced with method study and ergonomics). (c) Remunerate each worker with large pay when he accomplishes his task. (Industrial Engineer evaluates the job and translates the work content into money. So we interface this activity with wage fixation). (d) Make sure that when a workman fails, he is the loser there by. (Industrial engineer demarcates the targets of the job. Hence this activity is integrated with disciplinary actions of personnel or HR department). 2.9.2 Method Study Subsystem Methods study subsystem is concerned with the analysis of the methods and the equipment used in performing a job, the design of an optimum method, and the standardization of the proposed methods. This field is often cited as "method study", "motion study", "operation analysis" or "job design". Because of the economies that result from continuous methods improvement programs industry has long considered this one of the best avenues to manufacturing cost reduction and increased productivity. Methods study subsystem is the most important function of industrial engineer to ensure that the most efficient and effective methods are being employed. The industrial engineers may be assigned to a central methods engineering or industrial engineering department or may be assigned on a decentralised basis to individual operating departments. Some multi-plant companies maintain both a central industrial engineering group to work on problems common to many plants and also assign industrial engineers to each plant to work on projects pertinent only to that plant. It is clearly apparent that methods design may be either "before the fact" or "after the fact," i.e. it could consist of designing entirely a new process or system not previously used in the organisation or it may be the improvement of an existing process or workplace. In attempting to determine how much engineering time and effort can be justified on a methods project, the following factors should be considered. (a) The volume of production to be scheduled on the job, (b) The expected life of the product, (c) The current investment on machines, tools and equipment, and (d) The human considerations (training and retraining time, other human requirements and so forth). Approach to Methods Design Method design is a systematic approach that is far superior to the use ofa "h3t or miss" method. In its simplest form the industrial engineer uses this (PQRST-MODEL) approach through the following steps : I (a) Problem Identification : Identify the problem and then secure all known information about it to use suitable analysis techniques. (b) Question the present method : If any method exists, question the details of the known information to determine the lacuna. Systems Concepts rnd Industrial Engineering Industrial Engineering (b) To improve working conditions so as to enhance productivity of the system. (c) To create adequate facilities to reduce or eliminate the stresses, fatigue and failures in the performance of man-machine system. (d) To provide comforts and making the job easy. (e) To match the requirements of the task with the capabilities of a man and hence eliminate the loss in output. In every domain of technology, the man is involved. Therefore many situations in which the characteristics of man may conflict with the characteristics of technical procedures. Matching these characteristics is not an easy job since it is very difficult to trace the characteristics and their limits of tolerances in human beings. These depend on many factors such as geographic, demographic. economic and environmental reasons on one hand and physiological, psychological and anatomical reasons on the other hand. In a nutshell, we can say that the primary role of industrial engineer through ergonomic study is establishing the most optimum working conditions such as lighting, climatic conditions, noise level, work loads, working posture, gestures, psycho sensorial functions, displays, handling of machine levers, controls, etc. SAQ 5 (a) Explain the role of industrial engineering system in work study. (b) What is the role of the following subsystems with reference to the industrial engineering in an industry? (i) Time study subsystem (ii) Method study subsystem (iii) Ergonomics subsystem (c) How would you describe the subsystems of work measurement and methods engineering as the tools of lndustrial Engineer for enhancement of efficiency? (d) What is method design? Explain briefly the PQRST model and SREDlM techniques. 2.9.4 Productivity Subsystem The managing of production firm today presents a greater challenge than ever before. Top management is immersed in an endless stream of problems that evolve from continuing inflation, energy crisis, high taxes, government regulations, shortage of capital, dissatisfaction of workers, declining productivity and intense foreign competition. Any daily newspaper or newsmagazine provides the idea of the magnitude and the crux of these problen~s and the efforts to offset price increases, to mobilise funds for plant modernization, to increase productivity, to meet foreign competition and so on. It has not taken long time for an industrial engineer to recognize that high productivity has been one of the keys to the high standard of living. Further. it does not require extensive analysis to state that productivity is the backbone of the nation's economic progress. The standard of living is high in the countries where productivity is high. Thus increasing productivity should be a national challenge, and it behooves all industrial engineers to do their best to achieve ever-increasing levels. 2.9.5 WageIIncentive Fixation Subsystem Systems Concepts and Intlustrial Engineering Wage or Incentive fixation subsystem involves in deciding whether it is fair and adequate. It is very difficult to arrive at a decision, which will be satisfactory to both for the management and the workers. The arrival to a satisfactory solution is influenced by many factors, which are usually encountered in practice. It is only industrial engineer, who can do justice in finding an appropriate solution by translating the work content into the terms of money. This activity is termed as wage fixation. If at all, these wages are fixed by any other than industrial engineer, it should be either in the firm where there is no industrial engineering department is existing or he is doing industrial engineer's job deviously. On one hand, the industrial engineer has to formulate the work content by proper job evaluation, and on the other he has to design the incentive formula for those who work extraordinarily. A brief discussion in this regard is given below to familiarise the role of industrial engineer in wage and wage incentive fixation. According to American Society of Mechanical Engineers (ASME), a wage incentive scheme is defined as "A method ofpayment, which directly relates earning to the production and a system, which enables workmen to increase their earnings by maintaining or exceeding an established standard ofperformance". In other words, the wage incentive scheme is the tool used by the Industrial engineer to stimulate the production by encouraging the workmen to achieve more than the average or an established standard by putting an extra effort. In fact, it is very difficult to bring out an exact mathematical equation between the extra effort put by the worker and the extra money he gets for that work. The incentive scheme should be so designed that there should be a good recognition to the higher efforts. Thus it is very essential for the industrial engineer to have a thorough understanding on the amount of efforts required for every incremental production after standard. However, the following two points are considered while designing the scheme/system while calculating the incentive. Setting of Standards Here, the word 'Standards' refer to the time standards of a job. These standards indicate the time required to complete a defined target or definite out put or a piece of work or a certain service at desired level for a fixed wages and are treated as a yard stick to measure the effort of a worker. Establishing Relationship between Effort and Award This refers to fixing the rate or percentage by which additional amount of money will be earned by the worker over and above the set wages if he saves standard time exceeds the standard output. The rewards of incentives are fixed based on the considerations of the factors such as quantity of work, technical efficiency, quality of output, personnel assessment or a blend of these factors in an appropriate proportion. In general practice three policies are adopted viz. Individual incentive policy, group incentive policy and Fringe benefits. An industrial engineer may choose one of these policies or may choose one policy for one shop and the other for another depending on their suitability. Though there are number of incentive plans developed from time to time, every organisation develops their own plan to suit their requirement and availability and operating conditions. However, the basic plan and the formula remain same. These would resemble one of the plans developed during the second half of the 2oth century namely, Piece work, Standard hour plan, Taylor's differential piece rate, Merrick's multiple piece rate, Measured day work, Halsey's plan, Bedaux's plan, Rowan's plan, Emerson's plan, Cost saving-sharing plans and Profit sharing scheme. I An industrial engineer has to bear the following points while he designs a wage or wage incentive system : I (a) The system must guarantee the minimum day wage. Industrial Engineering (b) Workers' consent must be taken before fixing the wage. (c) It must respect the capacity and merit of the worker. (d) It must be simple to calculate and easy to understand. (e) It should be in such a way that it reduces the clerical costs. (f) It must aim high productivity without affecting the quality. (g) It should ensure the minimum wastage and maximum utility of resources such 4s manpower, material, equipment, money, time and other facilities in the plant. (h) It should have an optimum and effective supervision (neither too little nor too high). (i) Payments must be made timely. (j) It must be agreeable to both groups viz. The employees and the employers. (k) The system should not give any scope of dissatisfaction to the employees for wage differentials if any. (I) The wages must be in such a way that the workers would not go in any unrest and disturbances. Peace and harmony is an outcome of observed by a good wage system. Calculation of incentive for white-collar jobs and for indirect workers is another important and difficult task that challenges the role of an Industrial Engineer. Often industrial engineers choose the group incentive policy for these. The measurement of excessive effort in these cases is indeed a tough job. However, Management By Objectives (MBO) has been proven as a material tool that Industrial Engineers can employ successfully in most of the cases. SAQ 6 (a) What is productivity subsystem? What is industrial engineer's role in increasing productivity of a firm? (b) How is industrial engineer so significant in fixing the wages and incentives of industrial jobs? (c) What are points that an Industrial Engineer should bear in mind while designing a wage or wage incentive? 2.9.6 Research, Development and Engineering Subsystem Research and Development (R&D) is an important function of Industrial Engineer. In some industries (R&D) is a separate department either working under industrial engineering or industrial engineering to work under R&D or both to work in parallel. If we leave the debating question of who to report to whom in between IE and R&D, the activity that both perform is same with more or less same objective. This activity is to concern with the development of new product or process and in the improvement of the existing products and processes. The terms, such as research, development and engineering in fact are the core concepts of Industrial Engineering. Research It is an activity of attempts to discover and uncover new principles or methods or systems or processes or procedures or products, etc. The research may be pure or applied. Pure research has no practical application, while the applied research can point towards the solution to practical problems. importance of the circuit since its impact on performance was very marginal. The Industrial engineer of the company recommended that instead of using plywood the company should use transparent plastic back-covers for the chassis. This would allow the customers to see the circuit and decide for himself the truth of the company's claim. This is an innovation because it makes a vital difference to the customer, since he can see and understand for himself the improvement. Systems Concepts and Industrial Engineering Very often it is the customer himself who provides the source of innovation. A study conducted by Eric Von Hippel and James Utterback on the source of innovation in the scientific instruments business revealed that more than 75 percent of ideas for innovations came from users. To plan and manage for innovation as an on-going task, the first thing the Industrial Engineer must do is to maintain close contact and relation with marketing department. The firm's salesmen provide the most direct link for the company with its customers. The task of Industrial Engineer is to train these salesmen to keep their eyes and ears open for any type of information, ideas, suggestions, complaints, criticisms, and feed it back to the company. An extensive innovation study conducted by Christopher Freeman has concluded that successful companies pay a great deal of attention to the market. Successful firms innovate in response to market needs, involve * potential users in the development of the innovation, and understand users' needs. Keeping track of competitor's activities and moves can also be a source of innovation as can improvements in technology. To qualify as innovative, the technology must be market and customer-oriented rather than research-oriented. In most cases, innovation as finally introduced in the market was never originally intended to be so. You can appreciate the truth of this statement better when you know that xerography was originally aimed at a small segment of the lithography (a special type of printing process) market, it was never intended to be used in making mass copies. Transistors, which, prior to the development of integrated circuits, were used in manufacture of television, radio, etc., were originally developed for military use. As an Industrial Engineer you should keep a close watch on the technology improvements taking place and try to find a customer-oriented application for it. The Industrial Engineer who has his finger on the pulse of the market can quickly find out under-the-surface changes and shifts taking place and accordingly modify his product, and thence the process to match the customer requirement. It is not the absolute amount of money and effort, which a firm invests in research and development but its ability to quickly adapt and place in the market the improved product, which accounts for its innovation and care for the customer. This calls for flexibility in organisational structure to accommodate the necessary changes. In the final analysis, it is the Industrial Engineer who inculcates and nurtures curiosity and an open mind, and combines it with market feedback, who will emerge as winner in the race in which innovation is at a premium. Therefore, in simplest words, we can conclude that customer means the requirement and producer means the availability and Industrial Engineer's role is to match these two at a most optimum cost in right time. SAQ 8 (a) Customer means the requirement and producer means the availability and industrial engineer's role is to match these two at a most optimum cost in right time. Comment. (b) How far industrial engineer can succeed in maintaining the balance between the creativity and conformity in your view? (c) Explain innovation subsystem as tool for industrial engineer in achieving the operation effectiveness. Industrial Engineering 2.9.9 Information Subsystem - Management Information System (MIS) As speciallists, industrial engineer can secure and must work with information from many persons owing to his wide knowledge of various jobs and positions. Thus, they come in close contact with product engineers, quality control engineers, process engineers. production planning engineers, plant engineers, production supervisors, and many others. On major projects, methods engineers frequently may serve as chairmen of planning comrnitteds composed of such persons as product engineers, process engineers, quality control engineers, production supervisors, or others. For performing the above said functions effectively, an industrial Engineer always chooses to build up an efficient Management Information System (MIS). Management information system refers to that system by which information is collected, processed and presented to management to help it in making better divisions. An industrial engineer enables the top management to make improvised decisions all the time and anything which helps improve decision making will obviously lead to better results and it becomes a better management. In case of MIS, data is the input which is processed to provide output in the form of information reports, summaries etc To be really useful output, the information provided by Industrial Engineer must aid the managers good decision making. An Efficient Management Information System should be : S TA R Simple The information provided should be easy to understand and simple in using. The simplified/consolidated tabular forms, graphical aids (bar charts, Pareto's pie charts, graphs, scatter diagrams, etc.), pictorial views, drawings, diagrammatic representations, etc. will make the information to understand quickly. Delayed justice is denied justice. Information is useful when and only when it is within the limits of the decision. Accurate If the information presented is inaccurate, the management who makes decision based on this will invariably end up with mistake. Further, any spurious information is more dangerous than not providing the information. But the availability of 100% accurate information is very difficult. However, Industrial Engineer can only screen and refine the information to highest purity. Relevant Information systems for an exporter of cashew nut is of no value for manufacturer of sports goods. The industrial engineer himself can make an important contribution in ensuring relevance of the information to the official concerned. In simple words, Industrial Engineer is the Mariner's Compass for the ship like lndustry to show the right direction at right time. 2.9.10 A Subsystem to Meet the Challenge of Change One of the important tasks, which every industrial engineer has to perform, is that of a change agent. The social, technical and cultural environment in which the firm operates is always changing. The company must keep pace and change accordingly. Similarly, within the organisation, new types of production technology may be introduced, the existing product lines may be phased out, formal procedures and techniques for planning, resource allocation, job appraisal, etc. may be introduced. All these imply a change. And man by his very nature resists any change. Used to the old system or method of doing a particular job, people perceive change as a threat to their security. Moreover, change implies learning afresh the new methods or processes and most people resist making this extra effort. The marketing department of a television company always complained the low quality circuit in the black and white TV and held it responsible for its poor sales performance. However, when an improved circuit was introduced, the marketing department tried its best to convince the top management against this change saying that the old circuit was now performing in a satisfactory manner. The real reason, however, was that the marketing department would now be under pressure to show results as it would have no scapegoat to blame for its lack of results. The engineers responsible for providing after sales service opposed the new circuit since it meant putting in an effort to learn the new way of servicing it. There will always be change. It is the Industrial Engineer's task to ensure that the change is introduced and incorporated in a smooth manner with the least disturbance and resistance. Sharing information about the impending change, educating the people about the benefits resulting from changes and building favourable opinion of the key people in the organisation by involving them with the change process itself, go a long way in making the industrial engineer's task easy. The ideal way of introducing a change is that you, as an industrial engineer, simply sow the idea of the proposed change in the minds of a few people, and then let the idea grow and build till the people themselves come round to asking for the change. This is the way the Japanese make decisions- by consensus. However, it is not always possible to introduce change by having consensus. There may be limitation of time or money, or pressure of competition, which may make the consensus method impractical. SAQ 9 (a) Industrial engineer acts like Mariner's Compass to the Industry. Critically appreciate the statement. (b) In your view, how can an Industrial Engineer provide a purposeful direction to the firm? (c) What is the role of industrial engineer challenging change and in change management? (d) How should an efficient and effective management information system be? What are its characteristics? (e) What is role of an industrial engineer in providing purity in the . . information? 2.9.11 A Subsystem to Cope with Growing Technological Sophistication \ The two areas, which are witnessing dramatic changes in technology are production and information handling. In the area of production, technological sophistication has reached the level where the entire production plants are fully automated and programmed to run with the minimum human intervention. For instance, at Nissan's Zama plant, where Nissan cars are manufactured, the final assembly line operations are fully automated and controlled by robots. These robots have totally replaced men in such jobs in which the former can be programmed to perform round the clock without any fatigue or loss of efficiency. Robots are also being used in manufacturing, which requires handling of bulky and dangerous materials. All these changes in production techniques forced Industrial Engineers to find ways and means of relocating the workers rendered redundant. Simply laying off is not always the best solution as it can involve a very high compensation cost. Moreover, in many countries because of the government's political ideology or cultural values (as in Japan where the concept of employment with a company is life-long), laying off workers is not permissible. Systems Concepts and Industrial Engineering Industrial Engineering SREDIM Ergonomic Subsystem Incentive Innovation Subsystem Research Development Engineering Diversification Simplification Standardisation Innovation : The basic procedure of method study consists of the steps, Select, Record, Examine, Develop, Implement and Maintain the method. : An Ergonomic subsystem undertakes the study of the relation between man and his occupation, equipment and environment, and particularly the application of anatomical, physiological and psychological knowledge to the problems arising there from. : According to American Society of Mechanical Engineers (ASME), a wage incentive scheme is defined as "A method of payment, which directly relates earning to the production and a system, which enables workmen to increase their earnings by maintaining or exceeding an established standard of performance". : Innovation subsystem deals with the generation of innovative ideas, their collection/gathering, analysis, presentation and evaluation. : It is an activity of attempts to discover and uncover new principles or methods or systems or processes or procedures or products, etc. The research may be pure or applied. : It is the subsequent step of applied research and is usually connected with the fabrication of pilot plants to ensure the feasibility. This can also demonstrate the basic idea incorporated in the new product. : The activity to transform the work achieved from research and development groups into commercial benefit or profit by means of a product or a process that is capable of economical manufacturing. : For the prosperity and growth any company will think on the lines of adding new products to the product line or add more varieties or sizes of the product. This addition is known as diversification. : Simplification that reduces the number of varieties of finished products shows significant effect on both industry and public. : Standardisation is instituting of norms for quantity, quality, raw material, sizes and performance, etc. of any process or product done after conducting several experiments considering various scientific procedures. : Innovation is finding new, different and better ways of doing existing tasks. In the context of business, innovation has to be defined in terms of the additional value it imparts to the existing products of services. ! \ I Management Information : Management information System refers to Systems Concepts and f System that system by which information is collected, Industrial Engineering processed and presented to management to help it 1 in making better divisions. STAR Model of MIS : It is an acronym that indicates how a management information system should be, i.e. Simple, Timely, Accurate and Relevant. Knowledge Obsolescence : People cease to be productive and become a drag on the organisations in terms of their heavy cost and inability to make meaningful contribution. This is the problem of knowledge obsolescence, that is when employees become unproductive, or out of date or both. 2.12 ANSWERS TO SAOs I SAQ 1 (c) A village, a town, a city, a state, a country. Even religion, or religious behaviour, could be studied from the systems point of view. (e) Agriculture. In many systems, the various activities or actions are sequential, that is, have to be carried out in a definite sequence in time. (f) Although it is very difficult to define a biological system, you are already familiar with the use of some system concepts in biology. Thus, when studying plants, one talks about their parts such as root, stem, leaf, flower and seed. f SAQ 2 (a) For an RCC building, beams, columns, slabs and walls. (c) Bricks and mortar are the components. The various 'bonds' are the ways of interconnecting these components. (d) The electric supply network in the house, starting from the 'mains' switch, and going on with the wiring and the various switch-boards. ! SAQ 3 (a) The environment would be natural environment, and the disturbances could be changes in composition and condition of the surrounding air (humidity, carbon dioxide, etc.) and lack of food or nutrients. (b) (i) and (ii) - loads (inputs), deflections, strains, stresses (outputs), (iii) - frictional forces (inputs), wear (output). (c) It does not possible to think of concrete as a system since one cannot verify the invariance principles. The property or behaviour of concrete is quite different from the properties of cement and stone individually. However, RCC structure is usually treated as a system of concrete and steels bars interconnected so that the load is shared and the strains are related. (d) The rules and regulations, the laws, or the codes of conduct which are expected to be followed. Thus, if you go to a post office, it should be open for transactions when it is supposed to be open, and should provide for the stipulated transaction - buying postal stationary, sending a telegram at a cost, that is, on appropriate payment. Industrial Engineering SAQ 4 (a) (i) Floor size, ceiling height, wall thickness, slab thickness, so as to sustain a specified load and provide some level of comfort. (ii) The electrical power consumed at various speeds. (iii) Various steps of the speed, and efficiency. (b) Sizes of steel bars, grain of sand, strength and type of cement. Disturbances would be gusts of wind, dynamic loading, tremors.