In this paper, we will report on the outline and the vision for our plant modernization project and the recent results concerned with automation. The most important component of the project is ensuring the use of high capacity production facilities, introducing a complete centralised control system by the use of DCS (Distributed Control System) and superseding the process computer. We will also build management systems, such as production management system, quality control system, maintenance management system and decision-making support system through the plant host computer. It is thus our intention to build CIM (Computer Integrated Manufacturing).
Process Control Level
The process control computers take charge of stabilisation and optimisation of unit process control such as raw meal composition control, kiln control and so on. In our system, the process computer can freely access the DCS through the gate-way. If we install a new control programme in the process computer, it is not necessary to make an input/ output programme between the DCS and scheduling programme. We need to enter those parameters into our system. Also, we can maintain all process computers installed in the plants from our central head office by the use of a standardised network system.
DCS-PC level
The DCS and PC units are able to communicate with each other and likewise, the process computer can access PC via DCS. On this level, we emphasise that for the startup/shutdown and emergency control of the plant, the process computer can access all information, such as thermal trip, breaker off, local mode, detection of clogging etc. By such information, the reliability of the automatic procedure increases.
Real Time Quality Prediction System
In order to make the process control much more effective in the cement industry, it is necessary to combine it with the quality control system. The framework of the real time quality prediction system is based on the Ono-method. The estimated value is calculated by formula, and shown as an average of a half hour data on CRT in the control room. The procedure to produce a prediction formula for clinker strength is described as follows. The relation between the estimated strength of clinker and actual values of process variables is analysed by the use of multi-variable regression analysis. Without the Ono-method, one would have to wait a month for the quality test results, during which time a quality prediction system could not be established. The estimation formula which took in NOx, kiln drive torque and clinker temperature at the kiln outlet was judged to be applicable with the contribution degree at more than 60 per cent. The completion of the quality prediction system made it possible to establish an integrated system which unites the unit process control systems.
Kiln Control System
The kiln control system consists of the supervisor programme and subsystems such as steady state control, non-steady state control, cement type changing control and an emergency support system. This system manipulates kiln fuel feed rate, set-point of the bottom cyclone raw meal temperature control, raw meal feed rate, kiln revolution and IDF revolution. This system was installed in all kilns in our plants and has been operating satisfactorily up to now.
The supervisor programme has the right to select the outputs, which are requested at the same time from both the steady state and nonsteady state programmes. The processing of the supervisor becomes very complicated, for example, when the plural non-steady states occur at the same time. For that reason, we do not use procedural language for programming this system. The supervisor is programmed with production rules on OPS83. The programme is very clear and the extension of system becomes very easy.
Steady State Control System
The steady state control is based on the feedback of burning condition such as the kiln outlet clinker temperature and the kiln drive torque. However, as the cement rotary kiln process is slow to respond, we cannot control it only with a simple feedback. We used a model prediction control system on the background of a heat balance. Cement production via a rotary kiln is a non-linear process, but in the steady state control, the linear system model, which is linearised near the operating point, is used. For the prediction of the states (the heat transmitted to the raw meal in the kiln), the state transition equation is used. We can use state feedback control theory and calculate the feedback gains by the use of optimal regulator method. Our control system has a high robustness to the process fluctuations and moreover it is easily accepted by operators.
Non-Steady State Control System
In poor operational conditions, resulting from coating ring fall, etc, or in a severely weak kiln condition, we must control the kiln by logic different from that of above mentioned steady state control, until the kiln recovers to the steady state. For this purpose, we developed a non-steady state control system. This system is programmed with a production rule system on 0PS83. When the system judges the kiln state to be recovering, it takes a backward action. When it judges the kiln state to be returning to the steady state, it gives the control hegemony to the steady state control system.
The control for changing the type of cement is based on sequential control of raw meal feed rate, kiln fuel feed rate and set point of minor control loop for bottom cyclone raw meal temperature. The standard patterns for all types are set in the system, and they are automatically modified on the actual conditions when the changing procedure starts. The reference trajectories of the kiln outlet clinker temperature and the kiln drive torque are also made automatically, and if they turn aside from these lines during changing control, the sequential pattern is revised.
Optimising Control for Ball Mills
For the operation of ball mills, constant-value feedback control is generally adopted to increase productivity and secure quality. This control system is based on the principal that grinding efficiency of ball mills is the highest at a certain value of the bucket elevator power or the mill sound level. Therefore if the set point deviates from optimum setting, maximum efficiency is not assured. In fact, there are many factors which disturb the grinding process, such as fluctuation of grindability, particle size distribution and moisture of raw meal, abrasion of grinding media and so on. These disturbances bring about a shift of the optimum set point.
A hill-climbing method was used in this system whereby the set point is automatically changed at a certain time interval and the next direction of change in the set point is decided according to the comparison between the mill grinding efficiency before and after changing the set point. But we should be very careful in applying this method to an actual process. If the control parameters, such as the step width and the speed of the set point change, do not match the property of the process, the optimising control does not work effectively. To cope with the problem, we have developed a simulation programme for parameter matching as a support system and obtained very good results.
Cement Fineness Control
Various systems for automatic measurement of cement fineness have been announced up to the present. But these systems have not had widespread use in spite of their great importance for an efficient quality and production control. The reasons seem to be difficulties of quantification of the effectiveness and realisation of the reliability at proper cost. We installed a dry powder laser granulometer and developed an on-line cement fineness measurement and control system. The sampling and conveyance system is very simple, therefore the whole system is more reliable.
The measurement equipment is MICRO-TRAC Model made by Leeds & Northrup Instruments in the USA. The cement powder is sampled by a screwfeeder, transported by a pneumatic system and then measured in the dry condition. The samples of AJS are sampled manually in synchronisation with the on-line measurement. The process computer receives the fineness data from MICRO-TRAC, calculates the set-point of separator speed and then output it to the DCS.
Automation of Silo Process
Automation of the grinding process and the kiln process are not strictly complete until the automation of silos located before and behind these processes is also established. Namely, we can only start-up the mills on condition that the conveying equipment to the silo is operating. We developed an automatic cement silo input control system with a rulebased system. In this system we made use of progressive Al technology and our experience in roller mill startup/shutdown system. Namely we adopted the method changing K.S (Knowledge Source) sequentially as progress of interface (i.e. level management, product kinds management and so on). This method made it easier to adapt this system to the change in the production environment.
Conclusions
The ultimate target of automation is a no-man operation. There are many remaining problems concerning automation. The optimisation system of production planning has not reached a satisfactory level. The plant emergency control system must also develop. The reliabilities of sensors and automation systems have to be further improved. It seems that these systems need better developed technology but this is not so easy. Hardware technology, particularly micro-electronics, exhibits continuous rapid progress while software development is acquiring great importance to the automation engineer. It is vital that we research and develop automation systems — but always with an eye to the future [World Cement, October, 2009].
ECONOMICS
Text 10. What is Economics?
By R.E. Backhouse
Economics is notoriously difficult to define. Perhaps the most widely used definition of the subject is the one offered by Lionel Robbins: “Economics is the science which studies human behaviour as a relationship between ends and scarce means which have alternative uses.” The phenomena we associate with economics (prices, money, production, markets, bargaining) can be viewed either as consequences of scarcity or as ways in which people try to overcome the problem of scarcity. Robbins’s definition goes a long way towards capturing the features common to all economic problems, but it represents a very specific, limited view of the nature of such problems. Why, for example, should the operations of multinational corporations in developing countries, or the design of policy to reduce mass unemployment, be seen as involving choices about how to use scarce resources? It is perhaps ironic that Robbins’s definition dates from 1932, during the depths of the Great Depression, when the world’s major economic problem was that vast resources of capital and labour were lying idle.
A more natural definition is that of the great Victorian economist Alfred Marshall, who defined economics as the study of mankind in the ordinary business of life. We know what he means by this, and it is hard to disagree, though his definition is very imprecise. It could be made more precise by saying that economics deals with the production, distribution and consumption of wealth or, even more precisely, is about how production is organized in order to satisfy human wants. Other definitions include ones that define economics as the logic of choice or as the study of markets.
Perhaps as important as what these definitions say is what they do not say. The subject matter of economics is not defined as the buying and selling of goods, markets, the organization of firms, the stock exchange or even money. These are all economic phenomena, but there are societies in which they do not occur. It is possible, for example, to have societies in which money does not exist (or performs only a ceremonial function), in which production is not undertaken by firms, or in which transactions are undertaken without markets. Such societies face economic problems — how to produce goods, how to distribute them, and so on — even though the phenomena we normally associate with economic life are missing. Phenomena such as firms, the stock exchange, money and so on are better seen as institutions that have arisen to solve more fundamental economic problems, common to all societies. It is better, therefore, to define economics in relation to these more fundamental problems, rather than in relation to institutions that exist in some societies but not in others.
Anyone writing a systematic “principles of economics” has to decide on a specific definition of the subject and work within it. The historian, however, does not have to do this. It is possible, instead, to start with those ideas that make up contemporary economics — ideas that are found in economics teaching and are being developed by people recognized as economists. These, however, do not provide a precise definition, for the boundaries of the discipline are indistinct. Academics, journalists, civil servants, politicians and other writers (even novelists) all develop and work with economic ideas. The boundaries of what constitutes economics are further blurred by the fact that economic issues are analysed not only by “economists” but also by historians, geographers, ecologists, management scientists, and engineers. (Such writing may not be what professional economists would consider “good” or “serious” economics, and it may be ridden with fallacious arguments, but that is a different matter — it is still economics.) Approaching the subject in this very pragmatic way might seem less desirable than defining economics in terms of its subject matter. In practice, however, it is a workable approach and probably corresponds with what most historians actually do, even if they profess to work within a tight analytical definition of the subject.
Having decided on what constitutes contemporary economics, it is possible to work backwards, tracing the roots of the ideas that are found there, as far as it is decided to go. Some of these roots will clearly lead outside the subject (for example, to Newtonian mechanics or the Reformation), and the historian of economics will not pursue these further. Others will lead to ideas that the historian decides still count as economics, even though their presentation and content may be very different from those of modern economics, and these will be included in the history. The result of such a choice is that, the further we go back into history, the more debatable it becomes whether or not certain ideas are “economic”. When people argue that a particular individual or group is the “founder” of economics, they are claiming that earlier writers should not be considered to be economists.
This raises two major questions about writing the history of economics. Where should it begin? And is our perspective on the past distorted through being obtained through the lens provided by present- day economics?
Some historians have argued that proper economics does not begin until we enter the modern world (say the fifteenth or sixteenth century), or even till the eighteenth century, when Adam Smith systematized so much of the work of his predecessors. Economics, the argument runs, is about analysing human behaviour and the way people interact through markets and respond to changes in their economic environment. Early writers, it is claimed, had quite different concerns, such as moral and theological issues about the justice of market exchange or lending at interest, and their work should not be classified as economics.
There is, however, a big problem with this argument: it is simply not possible to draw a clear dividing line between what constitutes economic analysis and what does not, or between what constitutes “proper” or “real” economics and what does not. For example, the moral and theological arguments of medieval theologians about the justice of commercial activities presuppose an understanding of how the economy operates. The economic content of such writing may be half-hidden or obscure, but it is there. The view underlying this book is that economic ideas were present even in antiquity, and that those ancient ideas are relevant in trying to locate the origins of modern economics. Furthermore, even in the present century, economics deals with normative questions (questions about what ought to be done), some of which parallel those tackled by the ancients. Economists are forever arguing that this policy or that will improve the welfare of society. It may be unfashionable to think of this as involving ethics, or morality; nonetheless, ethical presuppositions underlie modern economics just as much as they underlay Aristotle’s thinking about the market. The Old Testament contains many economic ideas, as does the poetry of Homer. In a general history of economics, it may not be necessary to dwell long on these texts, but they are part of the story.
My argument can be summed up by saying that economics does not have a beginning or a “founder”; people have always thought about questions that we now consider part of economics [The Penguin History of Economics, 2005].
Appendix 3
ГРАММАТИЧЕСКИЙ СПРАВОЧНИК
Unit 1
1.1. Структура простого повествовательного распространенного предложения
В английском языке грамматические отношения между словами в предложении выражаются, главным образом, порядком слов и предлогами. Для английского предложения характерен фиксированный порядок слов: каждый член предложения имеет свое определенное место. В простом распространенном повествовательном предложении следующий порядок слов: 1) подлежащее, 2) сказуемое, 3) дополнение(-я), 4) обстоятельство(-а):
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Дополнения также располагаются в строго определенном порядке: 1) косвенное беспредложное (кому?, чему?), 2) прямое (кого?, что?), 3) косвенное предложное (с кем?, для кого?).
John gave те a book. = John gave a book to me. He is translating the text.
She wrote about her research.
Место обстоятельства времени более свободно: оно может стоять в конце или в начале предложения. При наличии нескольких обстоятельств, они располагаются за глаголом или дополнением следующим образом: 1) обстоятельство образа действия, 2) обстоятельство места, 3) обстоятельство времени. Если обстоятельство времени выражено наречиями always, usually, often, seldom, sometimes и другими, то оно обычно ставится перед смысловым глаголом.
They often publish their research findings.
He presented his research last week. = Last week he presented his research.
She translated that article with the dictionary at the university library yesterday.
Определение может относиться к любому члену предложения, выраженному существительным.
1.2. Типы придаточных предложений
Сложноподчиненное предложение {the complex sentence) состоит из главного предложения {the principal clause) и одного или нескольких придаточных (the subordinate clauses), поясняющих главное предложение. Придаточные предложения подразделяются на: 1) придаточные подлежащие, 2) придаточные сказуемые, 3) придаточные дополнительные, 4) придаточные определительные, 5) придаточные обстоятельственные.
Г) Придаточные подлежащие (subject clauses) выполняют в сложном предложении функцию подлежащего и вводятся союзами that что, whether (if) ли и союзными словами who(m) кто (кого), whose чей, what что (какой), which который, when когда, where где (куда), how как, why почему.
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2) Придаточные сказуемые (predicative clauses) играют роль составной части сказуемого и вводятся теми же союзами и союзными словами, что и придаточные подлежащие.
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3) Придаточные дополнительные (object clauses) выполняют в сложном предложении функцию прямого или предложного косвенного дополнения, отвечают на вопросы what? что?, about what? о чем?, for what? за что? и т.д. и соединяются с главным предложением теми же союзами и союзными словами, что и придаточные предложения подлежащие и сказуемые.
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4) Придаточные определительные (attributive clauses) выполняют функцию определения и отвечают на вопросы what? which? какой? и соединяются с главным предложением следующими союзными словами: местоимениями who(m) который (-ого), which (that) который, whose чей, а также наречиями when когда, where где (куда), why почему. Определительные придаточные, в которых речь идет о людях, вводятся местоимением who (that), а определительные придаточные, в которых говорится о неодушевленных предметах или животных, вводятся местоимением which (that). Если местоимения who(m), which, that являются в предложении не подлежащим, а дополнением, они обычно опускаются.
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Если перед местоимением стоит предлог (о котором, с которым, для которого и т.д.), то при пропуске местоимения он ставится после глагола, а при наличии дополнения — после дополнения.
The scientist you wanted to talk to is coming next week.
This is the book you are looking for.
5) Придаточные обстоятельственные (adverbial clauses) выполняют функции различных обстоятельств. По своему значению они делятся на обстоятельственные предложения: а) времени, б) места, в) причины, г) следствия, д) образа действия, е) уступительные, ж) цели, з) условия.
а) Придаточные предложения времени вводятся союзами when когда, while в то время как, before до того как, after после того как, till (until) пока, до тех пор пока... (не), as long as пока, до тех пор пока, as soon as как только, since с тех пор как.
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б) Придаточные предложения места соединяются с главным предложением союзными словами where где (куда), wherever где бы ни (куда бы ни).
I’d like spend my vacation Я бы хотел провести отпуск where I was born. там, где я родился.
Wherever she came, she was al- Куда бы она ни приходила, ее ways welcome. всегда радушно принимали.
в) Придаточные предложения причины соединяются с главным предложением союзами because потому что, as так как, since так как, поскольку, for так как, ибо.
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г) Придаточные предложения следствия соединяются с главным предложением союзом so that так что.
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д) Придаточные предложения образа действия вводятся союзами as как, as if (as though) как будто, как если бы.
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е) Уступительные придаточные предложения соединяются с главным предложением союзами though (although) хотя, in spite of the fact that, notwithstanding that несмотря на то что.
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ж) Придаточные предложения цели соединяются с главным предложением союзами so that, so, in order that чтобы, для того чтобы, lest чтобы... не.
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з) Придаточные предложения условия соединяются с главным предложением союзами if если, unless если только не, разве только, provided (that), providing (that), on condition (that) при условии что.
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1.3. Эмфатическая (усилительная) конструкция It is... that
Для выделения какого-либо члена предложения, чтобы подчеркнуть его значение употребляется сложноподчиненное предложение с конструкцией It is... that., переводимое на русский язык простым предложением со словами именно, как раз перед выделенным членом предложения.
It is (was) + выделяемый член + that (which, who) + подлеж. + сказуемое
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