Friday, January 24, 2020

Overpopulation :: Human Population

During the first 2 million or so years of its history the human population was a minor element in the world ecosystem, with at most 10 million members. In the New Stone Age, less than 10,000 years ago, the number of humans began to increase more rapidly. The rough equilibrium maintained before Neolithic times gave way when the human population developed agriculture and animal husbandry and no longer had to spread out in search of game. With the abandonment of a hunting-gathering way of life and the rise of permanent settlements and eventually cities, the human population underwent dramatic growth. By the beginning of the Christian era it had reached 250 million, and by 1650, half a billion. Growth of population during 20th century was very rapid. In 1994 the total world population was estimated at about 5. 6 billion people. It increased nearly by 4 billions of people during past 100 years. The most significant world trend is that death rates are currently falling in poor and rich countries alike, while birthrates remain high in most poor countries and low in most rich ones. Exceptions are the generally higher death rates of Africa and the high birthrates of the rich oil-producing countries. The most populous countries, in descending order, are China, India, the United States, Indonesia, Brazil, and Russia. The U.S. population totaled about 260. 8 million in 1994. In the 1990s about 4. 1 million children were born annually in the United States, and more than 2. 1 million persons died yearly. The greater number of births is due in part to a fertility rate that has increased by nearly 20 percent since the mid-1980s. International immigration, both legal and illegal, is another major element in U.S. population growth. Legal immigration has recently amounted to about 1 million per year; illegal immigration is thought to be several hundred thousand. In China, the world's most populous country, the 1994 population was estimated at nearly 1. 2 billion, more than double the 1953 census population of 584 million in mainland China. China's annual increase has been estimated at 1. 1 percent annually. India's population of more than 911. 6 million people (1994 est.) is increasing faster than that of China, and if present trends continue, it will soon catch up with or surpass China. Since the disintegration of the USSR, Indonesia and Brazil are now the fourth and fifth most populous countries, with 1994 estimated populations of 199.

Wednesday, January 15, 2020

Design of Fuzzy Controller

Design of fuzzy controller for two tank interacting system Mohamed sabith KT Second year M. tech Dept of Electrical Engineering NIT Calicut Calicut, India [email  protected] com Dr. Abraham T Mathew Professor, Dept of Electrical Engineering NIT Calicut Calicut, India [email  protected] ac. in Abstract—The control of liquid level in tanks and flow between tanks is a basic problem in the process Industries. Vital industries such as Petro-chemical industries, Paper making industries, Water treatment industries have the coupled tanks processes. The level of fluid in the tanks and interaction between tanks must be controlled.The aim of the project is to model the the coupled two tank liquid level system and to design a fuzzy controller. For coupled tank systems with non linear and complex characteristics classical PID is difficult to achieve the desired response. Fuzzy logic control is a classic method by which dynamic performance and strong robustness is guaranteed. The projec t compares the performance of the two tank system with classical PID and fuzzy logic control. Index Terms—PID, fuzzy logic, steady state Introduction through two separate pumps whose output is throttled using a control valve.Separate disturbance are made to both the tanks using hand valves. The two tanks are connected by means of hand valve, so the level of tank 1 will affect the tank 2 and vice versa. So this is a highly non linear system. Flow transmitters and pressure transmitters are there which give indication of flow and level respectively in a scale of 4-20 mA. The input from this sensors are taken to a computer which is process by a software in which controller is implemented which will give necessary control signal to throttle the control valve to get the necessary level.A Coupled tanks process is found in the many industries. Generally, The TITO processes have the problems to control their systems because of the existence of interactions between input and output var iables. Many control methods such as 2DOF PID [1], Auto tuning PID [2], CDM [3] and Decoupling [4] have been applied to coupled tanks processes for solving their problems. This paper presents control of two tank interacting system with the help of classical PID and Fuzzy control. The paper is organized as follows.The next section gives details about Coupled-tank process. Section 3 explains about modeling of two tank interacting system. Section 4 explains PID based control. Section 5 explains an implementation of Fuzzy Controller for coupled tank process. Section 6 shows experiment process and results. Finally, conclusions are given in section 7. COUPLED TANK SYSTEM MODELLING OF A TWO TANK INTERACTING SYSTEM Consider the coupled tank, two-input two-output process . The target is to control level of two tanks by the inlet water flow from two pumps P1and P2.The process inputs are flow rate of two pumps u1(t)and u2(t) which is throttled using control valves. The nonlinear plant equation s can be obtained by mass balance equation The overall material balance on the cylindrical tank is: Rate of mass accumulation in the system = rate of mass entering in the system- rate of mass leaving the system There for the dynamics of the tank system can be written as The coupled tank apparatus is shown in the Figure 1. 1. The apparatus is a model consisting of a pump, two cylindrical tanks made of plexiglas, two control valves, and two level transmitters .The two tanks are installed in a manner as shown in the fig 2. 1The water input to both the tank is provided 1 1 = ? 1 ? 1 ? 2 ? ? 1 + ? ( 2 ? ? 2 ? (2 ? ? 1( ) 2 2 = ? 2 ? 2 ? 2 ? ? 2 + ? ( 2 ? ? ( 1 ? 2 ? ? 2 Where A is the cross section area of tank 1 and tank 2, a is the cross section area of outlet hole of tank 1and tank 2 and cross section area of jointed pipe between tank 1 and tank 2 , ? 1 is the valve ratio at the outlet of tank 1, ? 2 is the valve ratio at the outlet of tank 2, ? x is the valve ratio between tank 1 and tank 2. k1,k2 are the gain of the pump. The above equations can be converted to transfer function form and a transfer matrix of the form is obtained. ?1( ) 11( ) 12( ) = ? 2( ) 21( ) 22( ) 1( ) 2( ) nteraction between processes, the control design needs the decoupling controllers to minimize the cross coupling effects Because of the interaction between processes, the control design needs the decoupling controllers to minimize the cross coupling effects The decoupling controllers consist of two decouplers d12 and d21 . The purpose of using decouple is to decouple the multivariable system. This can be done by choosing the following transfer function. D21=-G21/G22 D12=-G12/G11 SIMULINK SIMULATION OF COUPLED TANK SYSTEM WITH PID CONTROL AND DECOUPLERS The modeled coupled tank system was simulated using simulink .G11 represent the dynamics of the tank 1 ,similarly G22 represent the dynamics of tank2. G12 represent the effect of level of tan k 2 on tank1,and G21 represent the effect of level of tank 1 on tank 2. Due to high interaction between the tanks ,its difficult to control with ordinary PID. So as to avoid the interaction Decouplers were introduced. The advantage with the decoupler is that separate PID controllers can be designed for individual loops. Two individual PID controllers were designed for the two loops and tuning of the controllers were also performed.Tank 1 is subjected to a setpoint input of 15cm at time of 30 seconds and it is having an setpoint of 5cm. Similarly Tank 2 is subjected to a setpoint input of 25cm at time of 50 seconds and it is having an initial setpoint of 10. The response of the simulated system is shown in fig below,both the level of tank 1 and tank 2 follows the setpoint with small peak overshoot. Where h1, h2 are the liquid level in two tanks and u1,u2 are the input into the two tank . Where transfer matrix Gij(s)has the value as following G11(s)= 1 + 2 + 2 1 + +2 1 2 1 1 1 2 + +( + + ) 1 2 1 2 1 2 G22(s)= 2 + 1 + 1 1 + 2 +2 1 2 1 1 1 2 + +( + + ) 1 2 1 2 1 2 2 1 1 + 2 +2 1 2 1 1 1 2 + +( + + ) 1 2 1 2 1 G12(S)= G21(S)= 1 1 1 + 2 +2 1 2 1 1 1 2 + +( + + ) 1 2 1 2 1 2 Design of Decouplers The theoretically modeled system was simulated using simulink as shown in fig. below . G11(s) represents the tank 1 and G22(s) represents the tank 2. The effect of tank 1 on tank 2 is given by G21(s) and the effect of tank 2 on tank 1 is given by G12(s). This coupled tank system is having high interaction and it also exhibits non linear characterstics.Because of the The input variable error(e) is shown below,for all these inputs five membership functions are used. The five membership functions are NB,N,Z,P,PB. Fuzzy controller The traditional control, which includes the classical feedback control , has encountered many difficulties in its applications. The design and analysis of traditional control systems are based on their preci se mathematical models, which are usually very difficult to achieve owing to the complexity, nonlinearity, time varying and incomplete characteristics of the existing practical systems.One of the most effective ways to solve the problem is to use the technique of intelligent control system, or hybrid methodology of the traditional and ntelligent control techniques. The output variable is shown below As i have 2 inputs with 5 membership functions,I used 25 rules(IF THEN ). The surface of the rulebase is as shown below The above fig shows how a fuzzy controller is implemented . The Fuzzy controller takes two input and have one output, error and rate of change of error are given as input to the fuzzy controller . depending on the input the fuzzy controller produces required control action.For all input and output triangular membership functions are used. The input rate of change of error(de) is shown below The two tank system with fuzzy controller is subjected to an input,the first tan k is set to a initial level of 5cm then it is subjected to a step change of 15 cm at 25 seconds,for the second tank it is set to a initial level of 10 cm and final level of 20 cm. With fuzzy controller the outputs obtained is as shown below [1] Suparoek Kangwanrat1, Vittaya Tipsuwannaporn ? Design of PI Controller Using MRAC Techniques for Coupled-Tanks Process? International Conference on Control, Automation and Systems 2010 Oct. 7-30, 2010 in KINTEX, Gyeonggido, Korea [2] V. R. Ravi , T. Thyagarajan ? Application of Adaptive Control Technique to Interacting Non Linear Systems† IEEE Transactions On Systems, Man, And Cybernetics—Part B: Cybernetics, 33( ), 2003, 514–521 [3] [3] Dr. S. AbrahamLincon, P. Selvakumar ? Design of PI Controller using Characteristic Ratio Assignment Method for Coupled Tank SISO Process? International Journal of Computer Applications (0975 – 8887) Volume 25– No. 9, July 2011 [4] Li LIANG ? The application of fuzzy PID contr oller in coupled-tank liquid-level control system?IEEE Transactions on Industrial Informatics, vol. 6, no. 1, pp. 25-35, 2010 [5] Jutarut Chaorai-ngern, Arjin Numsomran, Taweepol Suesut, Thanit Trisuwannawat and Vittaya Tipsuwanporn ?PID Controller Design using Characteristic Ratio Assignment Method for Coupled-Tank Process.? Proceedings of the 2005 International Conference on Computational Intelligence for Modelling, Control and Automation CONCLUSION The output obtained for fuzzy controller doesnot show peak overshoot as in th case of a PID controller ,the problem observed with fuzzy controller is that small oscillations will be prescent at steady state REFERENCES

Tuesday, January 7, 2020

Distinctive Visuals in Run Lola Run Essay - 1190 Words

A composer can create images dependant on the form of the language of texts to shape a responders understanding of the ideas and themes prompted by people and their experiences. The German film, ‘Run Lola Run’ written and directed by Tom Tykwer, focuses on the experiences of the protagonist Lola to explore the themes of the inevitable force of time, and the issue of freewill verses determinism. Similarly, Dorothea Mackellar, in her poem ‘My Country’, relies on her experiences of the Australian landscape to convey her love and passion for the country using the language of the distinctive visual. The distinctively visual techniques employed by Tykwer in Run Lola Run, function to raise the importance of time, its inevitability, and†¦show more content†¦Split screen techniques divide the screen into three equal proportions creating a simultaneous depiction of Lola, Manni and the clock, allowing Tykwer to show the struggle to beat time. Adding to the dramatic urgency and reinforcing the power of time is the virtual real time of the film, meaning the twenty minutes of Lola’s life are shown in virtually twenty minutes of screen time. Hence, the distinctively visual provides an insightful image into Lola’s experiences placed under seize by the adamant nature of time. Interestingly, visual techniques are also effective in portraying the theme of free will versus determinism to question the responder who and what controls our lives. The tripartite storytelling structure incorporating three wholly, self-contained alternate versions of events is an unconventional filming technique reinforcing the postmodernist perception of having minimal control over life. As Lola rushes past minor characters in the film, flash forwards offer alternate glimpses of the possible outcome of their future, suggesting that fee-will alone is not a sole determination of the outcome of life. In each run, Lola’s encounter with these minor characters varies, showing that even the slightest change can become a significant impact to life. An extreme close-upShow MoreRelatedRun Lola Run and Related Texts.1339 Words   |  6 Pagesquestion distinctively visual images convey distinctive experiences, Evaluating the idea that visual images give us distinct experiences and how certain experiences can change our destiny. I will discuss this question using my chosen theme that is destiny, In Tom Tyker’s Run Lola Run and my related text Charlie Kaulfmans and Michael Gondrys Eternal sunshine of the spotless mind. Tom Tyker uses the theme of destiny to show how interaction between individuals can create a distinctive experience. Read MoreCompare the Ways the Distinctively Visual Is Created in Run Lola Run and in One Other Related Text of Your Own Choosing?941 Words   |  4 PagesCompare the ways the distinctively visual is created in Run Lola Run and in ONE other related text of your own choosing? Distinctively visual is one which the composer of the text uses visual, spoken and written language to position the reader to elicit their ideas. This is a powerful means to enhance the appeal of texts for viewers. Tom Tykwer’s film Run Lola Run includes Distinctively Visual scenes throughout the whole film using Symbolism. The exhilarating film takes the viewer through an intenselyRead MoreThe Studio System Essay14396 Words   |  58 Pagesdecades, the movie industry in the United States and the rest of the world operated by according to these principles. Cultural, social and economic changes ensured the demise of this system after the Second World War. A new way to run Hollywood was required. Beginning in 1962, Lew Wasserman of Universal Studios emerged as the key innovator in creating a second studio system. He realized that creating a global media conglomerate was more important than simply beingRead MoreMetz Film Language a Semiotics of the Cinema PDF100902 Words   |  316 Pagesthe impression of reality by giving objects dimension, but it also contributes directly to that impression in as much as it appears to be real. It is, in fact, a general law of psychology that movement is always perceived as real—unlike many other visual structures, such as volume, which is often very readily perceived as unreal (for example, in perspective drawings). Albert Michotte van den Berck examined the causal interpretations—the impression that something had been pushed, pulled, thrown, etc