0. NoteThis is the second assignment from my Masters Applied Digital Information Theory Course which has never been published anywhere and I, as the author and copyright holder, license this assignment customized CC-BY-SA where anyone can share, copy, republish, and sell on condition to state my name as the author and notify that the original and open version available here. 1. IntroductionOn the previous assignment we generate a chaotic sequence based on skew tent maps, and this time we generate a binary sequence (either '0' or '1'). On this occasion we generate the chaotic binary sequence based on the threshold function. bin = 0 if (x < c) bin = 1 if (x ≥ c) When a sequence value 'x' is less than critical point 'c' the binary value will be '0' and when a sequence value 'x' is equal or greater to critical point 'c' the binary value will be '1'. For example the critical value is set as 'c' = 0.4 and chaotic sequence 'x' = [0.750000 0.416667 0.972222 0.046296 0.115741 0.289352 0.723380], the binary sequence will be 'bin' = [1 1 1 0 0 0 1] as Figure 1. 2. Probability of binary sequenceUsing the chaotic sequence based on skew tent map to generate binary sequence we compute the probability the sequence value will be '0' or '1' as 'P(0) = c' and 'P(1) = 1-c'. Using the skew tent map we can compute 'P(00) = c x c', 'P(01) = c(1-c)', 'P(10) = (1-c)c', and 'P(11) = (1-c)(1-c)'. On Markov's chain the probability that '0' will remain '0' is 'P(0|0) = c', '0' will become '1' is 'P(1|0) = 1-c', and so-on 'P(0|1) = c', 'P(1|1) = 1-c'. We continue the assignment using the previous assignment to generate the binary sequence and calculate the probability of '0' and '1' theoretically and the actual number of '0' and '1' on the binary sequence generated. We used the initial value 'x(1) = 0.3' and trials of 'c = 0.1, 0.2, 0.301, 0.4, 0.6, 0.7, 0.8, 0.9'. The total sequence generated is 2000000 values (2 Millions). The result is on Table 1. Table 1. Result of theoritical calculation and actual
While the theoretical probability was calculated based on the formula, we count how much '0's and '1's in the sequence consist of 2 Millions binary values. For example using 'c = 0.4' we got 799594 '0's and 1200406 '1's in the 2 Millions sequence. So the actual probability of '0' is '799594/2000000 = 0.399797' and '1' is '1200406/2000000 = 0.600203'. For '00's is 319635, '01's is 479958, '10' is 479958, and '11' is 720449. Everything else is on Table 1, and actual data matched the theory. For Entropy and compression ratio is discussed on the next section. 3. Entropy vs Compression RatioOn this binary sequence we can calculate the entropy which is how much important information contained. The higher the entropy (more important information) the lower the compression ratio (the least it can be compressed). Based on Table 1 we also calculated entropy of the sequence with the following formula. Entropy = -P(1)log2P(1) - P(0)log2P(0) On this experiment the generated 2 million binary sequence is saved into a '.dat' file. The raw file for all 'c' value will equal to 2MB. Here we chose to compress the '.dat' file into '.tar.bz2' format which is a common compression method in Linux. Finally we can plot the entropy to the compression ratio on Figure 2 which is as stated in the theory that the compression value increases with lower entropy. 4. When t ≠ c is not memorylessWhen generating the binary sequence uses the threshold function bin = 0 (x < t) @ 1 ( x ≥ t), on above section it's automatically adjust that t = c to produce a memoryless binary sequence. One of the ways to show that the binary sequence is memoryless is that it fulfills Markov's chain on Figure 3, other than through the Bernoulli trials and independent and identically distributed (iid). We see that on table 2 that the probability is not balance, the probability of turning and remains '0' should be the same, same goes for the probability of turning to 1. Table 2. Data of t ≠ c
5. ConclusionUsing the chaotic sequence generated by skew tent map we can generate the random binary sequence with the probability of '0's and '1's computable. The result above shows that the theoretical probability of '0's, '1's, '00's, '01's, '10's, '11's, and the Markov's chain where the probability of '0' will remain '0', will turn to '1', '1' will remain '1', or turn to '0' matches from the actual binary sequence generated. The theory is true to the actual. On the second case where we compare the entropy to capability of the compression, the greater the entropy the less the compression ratio. We found that the sequence is not memoryless when t ≠ c because it does not fulfill the Markov's Chain. 6. Source CodeThe script is created in Ruby language, use Ruby to run. #!/usr/bin/ruby -w x = c = Array.new; binary_sequence = Array.new; $P0 = $P1 = $P00 = $P01 = $P10 = $P11 = $P0l0 = $P0l1 = $P1l0 = $P1l1 = 0; print "Input initial value x[1] from 0 ~ 1: "; x[1] = gets.chomp.to_f; print "\nInput critical point c[1] from 0 ~ 1: "; c = gets.chomp.to_f; print "\nInput number of sequence N: "; N = gets.chomp.to_f; for n in 1..N if x[n] >= 0 and x[n] < c x[n+1] = x[n]/c; elsif x[n] >= c and x[n] <= 1 x[n+1] = (1-x[n])/(1-c); else print "x must be from 0 ~ 1"; end end puts "P(0)_theory = c = #{c}"; puts "P(1)_theory = 1-c = #{1-c}"; puts "P(00)_theory = c*c = #{c*c}"; puts "P(01)_theory = c(1-c) = #{c*(1-c)}"; puts "P(10)_theory = (1-c)c = #{(1-c)*c}"; puts "P(11)_theory = (1-c)*(1-c) = #{(1-c)*(1-c)}"; puts "P(0|0)_theory = c = #{c}"; puts "P(0|1)_theory = c = #{c}"; puts "P(1|0)_theory = 1-c = #{1-c}"; puts "P(1|1)_theory = 1-c = #{1-c}"; puts ""; file = File.new("binary_sequence.dat", "w"); for n in 1..N if x[n] < c binary_sequence[n] = 0; $P0 += 1; elsif x[n] >= c binary_sequence[n] = 1; $P1 += 1; else print "something is wrong"; end #print binary_sequence[n]; file.syswrite(binary_sequence[n]); end P0_actual = $P0/N.to_f; P1_actual = $P1/N.to_f; for n in 1..N if binary_sequence[n] == 0 and binary_sequence[n+1] == 0 $P00 += 1; elsif binary_sequence[n] == 0 and binary_sequence[n+1] == 1 $P01 += 1; elsif binary_sequence[n] == 1 and binary_sequence[n+1] == 0 $P10 += 1; else $P11 += 1; end end P00_actual = $P00/N.to_f; P01_actual = $P01/N.to_f; P10_actual = $P10/N.to_f; P11_actual = $P11/N.to_f; P0l0_actual = P00_actual/P0_actual; P0l1_actual = P01_actual/P1_actual; P1l0_actual = P10_actual/P0_actual; P1l1_actual = P11_actual/P1_actual; puts "P(0)_actual = #{P0_actual}"; puts "P(1)_actual = #{P1_actual}"; puts "P(00)_actual = #{P00_actual}"; puts "P(01)_actual = #{P01_actual}"; puts "P(10)_actual = #{P10_actual}"; puts "P(11)_actual = #{P11_actual}"; puts "P(0|0)_actual = #{P0l0_actual}"; puts "P(0|1)_actual = #{P0l1_actual}"; puts "P(1|0)_actual = #{P1l0_actual}"; puts "P(1|1)_actual = #{P1l1_actual}"; puts ""; puts Entropy = ((-P1_actual)*(Math.log2(P1_actual)))-((P0_actual)*(Math.log2(P0_actual))); puts "Total of '0' is #{$P0}"; puts "Total of '1' is #{$P1}"; puts "Total of '00' is #{$P00}"; puts "Total of '01' is #{$P01}"; puts "Total of '10' is #{$P10}"; puts "Total of '11' is #{$P11}";
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0. NoteThis is the first assignment from my Masters Applied Digital Information Theory Course which has never been published anywhere and I, as the author and copyright holder, license this assignment customized CC-BY-SA where anyone can share, copy, republish, and sell on condition to state my name as the author and notify that the original and open version available here. 1. IntroductionThe chaos theory is a field of study in mathematics that studies the behaviour of dynamical system. Rober L. Devaney stated a system can be chaotic if it is sensitive to initial value, topologically mixing, and have a dense periodic orbit. The theory was summarized by Edward Lorenz. Although the system was highly determined by the initial value, in the end the sequence is unpredictable. Chaos exist in many natural system such as the climate and whether. In the field of computer science, it's applied to generate random values. 2. Tent MapThe tent map can be formulated as t = x/c for 0 ≤ x < c and t = (1-x)/(1-c) for c ≤ x ≤ 1 where: c = critical point x = initial value t = tent map (next value for sequence) For example c = 0.5 with x from 0 to 1: Figure 1 is based on the equation that the value would range from 0 to 1, and when “x” reached the critical point, the value of “t” will equals to 1. It is up to us to decide the critical point, as in Figure 2 shows if “c” equals to 0.2. Another information is if “x” equals to 0 or 1 the end result will be 0, thus using this value is not recommended. 3. Chaotic SequenceIn some areas the tent map equation is used to generate chaotic sequence, here t(n) = x(n+1). The equation would turn into x(n+1) = (x(n))/c for 0 ≤ x(n) < c and x(n+1) = (1-x(n))/(1-c) for c ≤ x(n) ≤ 1. Why the equation is stated differently? So the value of x(n+1) will never exceed 1. For example if “c = 0.4” and “x = 0.5” and use the first equation “x(n)/c = 0.5/0.4 = 1.25”. That won't do so we use “1-x(n)/1-c = 1 - 0.5 / 1 - 0.4 = 0.5/0.6 = 0.833”. Another example “c = 0.7” and “x = 0.4” which we can't use the second equation “1-x(n)/1-c = 1 - 0.4 / 1 - 0.7 = 0.6/0.3 = 2” but we use “x(n)/c = 0.7/0.4 = 0.571”. As stated in the chaos theory the next sequence “x(n+1)” is highly dependable on the initial value “x(n)” (x(2) depends on x(1), x(3) depends on x(2), etc), as we plot the sequences it will looked unpredictable. 3.1 For “x” equals to 0 and 1, and “c” equals to 0.5Figure 3 is only plotted to the 10th “n” because the result is obvious. For x(1) (initial) equals to 0, x(2) = 0/c = 0 and for x(1) x(2) = (1-1)/(1-c) = 0/(1-c) = 0. Once the value is zero, the next value will always be zero, and for x(1) equals to c x(2) = c/c = 1, x(3) = (1-1)/(1-c) = 0. When “x” reaches critical point “c” it will result to 1, and once the next value “x(n+1)” equals to 1 the next value “x(n+2)” will result to 0, and once it reaches to 0 the next value will always be 0. With the explanation above we can see that it's not recommended to use a critical point “c” equals to 0.5. In Figure 4b when “c = 0.5” it's susceptible for “x” in reaching “c”. On the 54th “n” “x(n) = c” and “x(n+1) = 1”, then the next result will always be 0. 3.2 For “c” equals to 0.6 and x = 0.3 and 0.8Figure 5a shows that when “c” equals to 0.6, “t” will have the same value when “x” equals to 0.3 and 0.8. Thus the sequence generated at Figure 5b will be the same. At the same time it is shown the sequence will be continuous. 3.3 Sensitivity to Initial ValueThe chaos theory stated that it is sensitive to initial value, just a slight change can totally change the whole sequence. For example “c = 0.4” and we'll try “x” with initial value of 0.7, 0.71, 0.72, 0.73 on Figure 6 and “x” with initial value of 0.7111, 0.71111, 0.711111, 0.7111111 on Figure 7. On Figure 7 we tried even more extreme which we plot of each initial value with a difference of 0.0001, 0.00001, 0.000001, and 0.0000001. There seems to be no difference on up to the 10th sequence, but the sequences finally deviated on the 15th “n” sequence for 0.7111 and 0.71111, then followed up by the other initial values that have smaller difference. Even with small difference it's still unpredictable on the 100th sequence, let alone the 1000th sequence. This proofs the sensitivity to initial values (where the “x” starts). 3.4 Distributions of the sequencesOn this section we will see the distribution of value from 0 to 1, specifically from 0, 0.01, 0.02 ~ 1. Only 0 to 1 because the sequence is formulated to not go below 0 and go above 1. The histogram on Figure 8 shows the distribution of value with critical point “c” of 0.4 and initial value “x(1)” of 0.7. This time we produce a sequence as much as “n = 1000000” (million) (the more the sequence the better). Plotting that much data cannot be seen in one graph, in other word it's not visible, but with histogram we can see what and how much the values contained in the sequence. Figure 8 shows that there is around 10000 data with a value of 0.1, 0.2, and so on. The hist() function works by rounding, for example the value of 0.1111 will be rounded to 0.1, and the value of 0.15 rounded to 0.2. Then the value is counted up (how many 0.1s there is) and a distrubution histogram was graphed. Finally it can be said that the distribution of data is uniformed since the amount of data for each value is almost the same. 4. ConclusionWe can conclude that the chaos sequence is formed by previous value like a memory system. Since it's very sensitive to initial value, the further the sequence becomes more unpredictable. The theory is a simple application of the natural system for example the weather. We can predict the weather maybe for a month, beyond that it's likely miss prediction. The course of whether is determined by its starting point, the wrong initial value will lead to the wrong prediction. On the other hand the more accurate the initial value and the formula, the longer the validity of the prediction. Since the unpredictable outcome of this chaos theory, in computer it can be also applied for creating random values. On this simulation the distribution of the skew tent to the chaotic sequence, we found it to be uniformed. 5. Source CodeThe source code is written in “m file” that could run on Matlab or Octave alike. It is a function which can be run as “stcsfp(xo,c,N)” where “xo = initial value”, “c = critical point”, and “N = number of sequence”. For example the plotted graph above we run by “stcsfp(0.7,0.4,1000000)”, but we can delete function if it seems inconvenient by deleting the 1st line and use it as regular script. The graphs above are done by few modifications of the code, but here on Code 1 resides the pure source code. function t = stcsfp(xo,c,N) % === TENT MAP === % X = 0:.1:1; for n = 1:11 if X(n) >= 0 && X(n) < c T(n) = X(n)/c; elseif X(n) >= c && X(n) <=1 T(n) = (1-X(n))/(1-c); else printf("x initial must be from 0 to 1"); end end % === MAIN CALCULATION === % x(1) = xo; for n = 1:N if x(n) >= 0 && x(n) < c t(n) = x(n)/c; x(n+1) = t(n); elseif x(n) >= c && x(n) <=1 t(n) = (1-x(n))/(1-c); x(n+1) = t(n); else printf("x initial must be from 0 to 1"); end end %Plot Tent Map% figure plot(X, T, xo, t(1)); title("Tent Map"); xlabel("X"); ylabel("T"); %legend("fill this in") %Plot Sequence% figure plot(t); title("Sequence Generated"); xlabel("n"); ylabel("t(n) or x(n+1)"); ylim([-0.1 1.1]); %legend(["fill this in"]); %xlim([1 20]) %Plot Histogram% figure hist(t, 0:.01:1); title("Distribution"); xlabel("Value"); ylabel("Count"); xlim([-0.1 1.1]); Code 1. Skew Tent Chaotic Sequence Program Mirrors
Back in high school and university in department of science and mathematic, it is compulsory to solve mathematical problem manually using theories through formulas. However in Engineering, it is the application that is important, and thus we are encouraged not to waste time solving manually and instead use simulators such as Matlab, Octave, and today there are online ploters. For example in one of my assignments in Signal and System Analysis course, I was asked to find periods in signal equations through visualization rather solving through formulas. Period is defined as a complete cycle. Mirrors
NoteAs the title suggest, the course is a collection of topics discussed by Professors in Kumamoto University which is compulsory for international students and optional for native Japanese students. Unfortunately I do not have all the materials and do not have the right to share them but I do have the right to share my assignments. Most the assignments are summaries or just my impressions about each sessions and not all of them survived since some are asked to be hand written. Either way, these assignments has never been published anywhere and I, as the author and copyright holder, license this assignment customized CC-BY-SA where anyone can share, copy, republish, and sell on condition to state my name as the author and notify that the original and open version available here. How Will the Feedback Control Technology be Useful or Beneficial in Your Future?IntroductionThe feedback control is one of the topics that is discussed in the subject of control system. It can be implemented in all fields but in my case, I mostly heard in field of Engineering usually in Electrical and Mechanical Engineering. The control system itself is the field of controlling a system where a simple control device can control the behaviour of another device, a remote controlled car for example. The remote controlled car is a user or manually controlled device which generally is not feeback controlled that tends to be automatic. A feedback control technology automatically controls the device with the general definition follows after Figure 1. Figure 1 above shows the block diagram of feedback control system where the desired output is controlled. The variable “input” itself is usually “desired output”, and “feedback” is the current “output”. The feedback system is a system where the current output is included into the calculation. For example an air conditioner is set an input of 250C, the current temperature is 270C will be the value of the feedback. The system will detect the difference in temperature that the room is still hot. The air condition will attempt to cool it down until it reaches 250C or lower, and once it reaches it the air condition will stop the cool down attempt. It will turn on again when the temperature rises. Current Daily Life ApplicationAir conditioner is a good commonly known example in the first section. Another example is the refrigerator which should have the almost the same method as the air conditioner. There's a block diagram thermoelectric cooler control on Figure 2. Another example of heat controlled device is the electric iron for ironing clothes. The heating process will stop if it reaches the desired temperature. There's still more examples like oven, microwave, dispenser, and heater during summer. Those are common examples that can easily be explained and tends to be very crucial if feedback control is not implemented. If iron, oven, dispensers, and stuffs over heat it will burn the clothes, the foods, spill the water, in worst case it might explode, cause fire, and casualties. Now days even computers and laptops are equipped with cooling features. The hotter the computer the faster the fan spins, and on the other hand if it cools down, the fan will spin slower. Those are essential control example in daily live, another very crucial example is the balance of helicopter issue, air plane, train, rocket, which are very dangerous if feedback control is not implemented. They're not daily lives thought. There are other feedback control that can be implemented which is not necessary but could benefit greatly. On my undergraduate I made an automatic dimming light consist of light and photo-transistor as its sensor with micro-controller. Other than the automatically turning on the light when it's night, turning it off when it's day, it can automatically adjust the light intensity based on surrounding light intensity. It's an automatic lighting system that could adjust to the desired brightness with the block diagram on Figure 3. This isn't crucial but it could save energy if it's implemented. Today's InnovationToday's feedback control system purposes are for efficient, richer, and safer life. Electric vehicles such as the segways and scooters are feedback controlled on the balance issues where it tries to maintain the center of balance. As for the building demolisher prevents shaking of the demolisher (the pendulum iron ball) to prevent accident. The latest control system technology is on automatic cars and robots. Latest car can drive automatically using the GPS to find the way, using the road's lines and signs to keep on track (line follower robot is the most basic), and few sensors to detect surroundings like other cars, bike, and people crossing the road. It's not that far where vehicles can automatically be called to get us using remote control for example. If autopilot is already possible, then all we need is to send our GPS location to our car, and will automatically come. Lastly on Figure 5 is a compilation of feedback control applications. Comment About Pulsed Power Science (3rd and 4th lecture)First I would like to admit that my knowledge of chemistry and environment is still insufficient but I would like to give my comments and suggestion from the public point of view. The lecture consists of “Development of environmentally benign biomass utilization processes”, “producing functional polymers“, and “synthesizing bio-active peptides”. The first comment I would like to give is about biorefinery with supercritical fluids. As the question that I asked on the previous lecture the idea is the cost of the refinery process in compare to the output whether they are fuels, power supply, or chemicals. If the input is larger than the output normally it's a loss, but biorefinery is a special case. Since it is the process of recycling waste is not necessary a loss if the cost to do the refinery is larger than the output. Instead I suggest to compare the cost used using conventional method and supercritical fluid method, then compare the output of those two methods. Which one is better? Another opinion is, maybe you may mix using supercritical fluids and conventional method. As for Supercritical CO2 Extraction and Micronization of Carotenoids I think it may proceed to the manufacturing side for next research. How is it if it's actually implemented in Industry? On PNIPAM polymers synthesis topic using pulsed power, there's a graphic of using pulsed power to produce with low frequencies and the conventional way. The conventional method produces on 5 minutes while using pulsed power can produce almost instantaneously. On the very low frequency the conventional method can produce higher yields when over 10 minutes pass. I propose, how about mixing the pulsed power method with the conventional method? Use the pulsed power method first, then continue with conventional method. Another thing is you may continue retrieving data for more frequencies. Again is it more expensive to use the pulsed power method? Are we ready to implement it? On synthesis of peptides using the same method, how about doing the experiment on the larger scale of volumes? If not possible due to current equipment, then I think we can provide datas with different volumes. Then to perform on large scale the first step can be done through theoretical, calculation, or simulation. Another curiosity, what if we do the experiment in different room temperatures? Lastly I would like to thank for your time for giving us lecture. With have another view of what is like in Pulsed Power department. I believed that learning many different things will widen our view, and make even more path possible. I prefer to learn a little of everything than just being closed to study one subject. One last advice, since some of us are not familiar on this field is very hard for us the grasp the lecture, so I suggest you may provide videos of your experiments. We find it harder to imagine based on the advance theory, but with videos we directly see your research. Noise Policy in Developing CountriesThis Lecture of Current Science and Technology on 18th and 25th January 2016 discusses about noise policy and later on to be implement in developing countries by Professor Takashi Yano from Department of Architecture and Environment Planning, Graduate School of Science and Technology, Kumamoto University. On the first lecture the very basics of what noises are, how can it occurs, and how the impact is to the environment. Then a policy was introduced for this noise including how the policy was created. Develop countries like Europe and Japan already studied early for these policies. The Professor states he would like to continue the research on implementing them on developing countries, on the second lecture his study of noise policy in Vietnam was introduced. On this topic noise is defined as unwanted sounds that bothers, cause disturbance, or cause annoyance. We can perceive sound in terms of energy, frequency, and temporal characteristic. Energy is more like the intensity of the sound with the higher the intensity the louder the sound. For us loud sounds tends to be nuisance. Frequency can correlate with pitch, women in choirs tends to have high pitch or high frequency or soprano sound, while men tends to have low pitch or low frequency or bass sound. The study between intensity and frequency have been conduct and we can refer to the research usually in form of graphic. With certain level usually high level of intensity are treated as noise. Where does noise came from? It can come from aircrafts, cars, trains, industrial, and many more. What are the effects of noise? It could be noise-induced hearing impairment, interference with speech communication, sleep disturbance, cardiovascular and physiological effects, mental health effects, performance, and residential behavior and annoyance. How does noise policies are made? First of is to get the scientific data of the noise by calculating the sound level in decibel (dB), not to forget to include the factors of daytime, evening, and night times. For example calculating the sound intensity of trains. Then get a social data by conducting surveys on people of getting their opinion of how annoying the sound is. In English it is either extremely, very, moderately, slightly, or not annoying at all. Another way is to use numbers or metrics and ask the people to fill it in. Finally a correlation between the level of annoyance and sound level is made usually in form of graphs. From here we derive of what sound level of certain object is tolerable in our policy. Studies in Europe shows an aircraft is more annoying on the same sound level rather than road traffic followed by railway. It's similar in Japan but railway is more annoying than road traffic, with these conditions bonus levels might be implemented in policies. These could be psychological issues and maybe others. The research aims to creates noise policies for all around the globe. The example above (noise policy in Europe and Japan) shows that each place might not be able to implement the same policies, because each place had their own characteristics. On the second lecture there was a survey conducted comparison of road traffic noise annoyance among Japanese, Vietnamese living in Kumamoto and Vietnamese living in Hanoi. The result was the Vietnamese living in Hanoi experience a certain sound level doesn't find it annoying at all, while for Japanese is already annoying. This could be due to the situation Vietnam very crowded in traffic and they are used to such noises. These arouse a question for me that will the noise policy be fixed? For example if the noises are reducing in the future wouldn't that change the opinion of the people on next generation? Research Idea on X-ray CT ScanIf you can use X-ray CT scanner for your study, what do you want to scan or study?If I can use an X-ray CT scan for my study, I would like to use them for examining and reverse engineering of electronic devices the non destructive way. The term reverse engineering means to break open the object to know how it works that later could be troubleshoot, revised, enhance, or duplicate. The normal way have a high chance of breaking the electronic device, or at least it can no longer return to the way it is. Reverse engineering on a phone for example will break the guarantee seal. Therefore it be nice if we can use X-ray CT scan to reconstruct the inside into 3D digital image. Furthermore I wanted to use this X-ray CT for education, if possible commercially available for everyone. So I hope a portable X-ray CT are to be developed as vision of the author of the paper I showed below. Search any papers using X-ray CT scanner or any other non-destructive test method with respect to your research.In the field of computer science, electrical engineering, or alike is more likely that we develop an X-ray computed tomography (CT) scanner, although not limited to that. We can for example use CT to monitor battery condition for example, or see whether CT can be use for reverse engineering of an electronic device. But most research are on finding algorithms for fast CT scan, develop the image processing, or upgrade the hardware as now nano-technologies are aggressively advancing. Here I would like to show a paper of “Towards a Flexible and Portable CT Scanner” by Jeff Orchard and John Yeow from Waterloo University, Canada on 2008, which was 8 years ago today the prototype probably exist. Even today we knew that X-ray CT scanner are very big and stationary, only available on the hospital, industries, or laboratories. It's not a public equipment, it's also high power consuming and produces high temperature. Like computers today can be portable (laptops, gadgets, PDA, etc) the thought came up of what if we can carry an X-ray CT scanner? To make this the author claimed that it is possible ever since the discovery of carbon nano tubes (CNT). CNT had the ability to project electrons when exposed to an electric field which is the one of the fundamental of X-ray CT. The author hadn't realized the device yet but simulates it when using flexible arrays in conjunction with X-ray detectors. The work before integrates the tiny x-ray devices into a flexible array such that each emitter can be individually pulsed. Through the simulation the author states that the challenge is within the irregular geometry shape (usually perfect circle). For this we have to treat scan as collection of individual ray sum. Other challenges were stated like the need of CNT to be in vacuum, the degradation of CNT structure, the unclear value of x-ray photon flux which determines the quality of the image, and some X-ray photons undergoes Rayleigh and Compton scattering. Short Report (Comments) of 8th and 15th December LectureBinaural Acoustic and Other ResearchMamiko Yada explained to me 2x at poster session and special seminar of her topic related to binaural hearing and bone conduction in determining the source of incoming sound. Koshiro Hira explained to me in his poster session on unidirectional sound for where each has anti sound waves of its opposing speakers so that it doesn't clash with each other, it's for evacuation pursposes. I too am a member of this Lab which my research continues Dynamic Synchronization of Learning Contents previously by Dr. Royyana. I do have an idea of audio distribution over wireless sensor network for emergency evacuation purposes on remote area. How to Return HomeFrom this I learned that the consequences of breaking the rule is more severe for foreigners than local citizen. Local citizen's suspension is more to social punishment while for let's say international student punishment must leave Japan. Using vehicle carefully is very important, even bicycle is regarded as an official vehicle. Plagiarism must be avoided at any cost. Don't save money if it relates to health and safety. For example buy thick clothes for Winter, becareful of disasters. But there is something still bothering me, and I highly suggest to explain deeply of this one. It's about copyright issues on The Internet. Back in Indonesia I don't have to worry anything when surfing on The Internet. I understand that you have to pay when downloading copyright materials, and uploading them is very severe. But what about just accessing the content like watching Youtube or reading online materials? Some say that you're not allow to download videos for example on Youtube, but what if there's no copyright on the video? It's the author's original video, and on Youtube he/she says it's free to distribute. Here P2P and file sharing software, it's said to be illegal, but I usually use them not for pirating, for example use torrent to download Linux and other open source software. Instead we encourage to use torrent because we wanted to widely distribute this free open source software. My Impression About This CourseOverall I really enjoyed the class, the materials were not complicated and interesting, the links shows to interesting page, the quiz helped me focus on the important part, the assignments were exciting where we get experiment in compressing image, analyzing website, making video presentations, and watched other's videos that had interesting topics. I liked this course because it's very flexible that I can attempt them on my leisure time on Saturday and Sunday for example with almost no burden. The course also reminds me what I did for my bachelor thesis, which is applying discrete wavelet transform on an image in application of wireless sensor network. The last section of the lecture was very difficult about user interface and universal design which the standards that was pointed to personally bear too much information. It's better to provide examples of a good and not okay page. For the videos I preferred accessing the through Youtube alike, maybe it can be note on the assignment to submit the file and recommended to upload them to Youtube. For the bandwidth consumption there's an option of introducing very high compression technique like x264. About the comment I said during the final face to face class, I thought that we should evaluated others presentation like the method on the picture below: These are my recorded assignments while the rest are not recorded because they are quiz sessions and has never been published anywhere and I, as the author and copyright holder, license this assignment customized CC-BY-SA where anyone can share, copy, republish, and sell on condition to state my name as the author and notify that the original and open version available here. The Professor wanted to change the course to something like Human Perceptions in Computers while actually the course name is Multidimensional Signal Processing. 1. Choose 2 Image Compression Method and Explain
2. The web site that I chose to examine is my former University www.unud.ac.id 2015, Udayana University with 5 issues:2.1 Readable: Make text content readable and understandable
2.2 Text Alternatives: Provide text alternatives for any non-text content
2.3 Navigable: Provide ways to help users navigate
2.4 Input Assistance: Help users avoid and correct mistakes
2.5 Predictable: Make Web pages appear and operate in predictable ways
3. Present a Journal Paper Related to Your Research
00:00 Opening 00:14 Title 00:30 Keywords: Dynamic Content Synchronization, Distributed Learning Management Systems, Course Sharing, Unidirectional Content Synchronization, Limited Bandwidth, Developing Country, Adding the update button on contents in LMS. For bandwidth efficient content sharing and support in collaborative content development. Demonstrated on Moodle 1.9. 00:44 Today ICT greatly supports education. 01:35 Motivation: equally distribute the learning contents (quality education for all). 02:51 Related Works: Moodleshare and Communityhub. 03:07 Contribution: novel method for sharing e-Learning content. 04:14 Content Synchronization: differential update using hashing technology. 04:54 Illustration 05:19 Concept 06:00 Coding Concept 06:58 Experiment 08:04 Result 09:16 Conclusion 09:31 Future Work Finally I would like to vote for the 5 following presentation: NoteThis is a summary about Biosignals in my Masters course of Bioinformation Engineering. If the passage is too much for you, then it is better to view the slide instead. This assignment except for the images which are from Miller Karol "Biological and medical physics, biomedical engineering" (2011), has never been published anywhere and I, as the author and copyright holder, license this assignment customized CC-BY-SA where anyone can share, copy, republish, and sell on condition to state my name as the author and notify that the original and open version available here. 1. Fudamental of BiosignalsFrom the biosignal is defined as a description of a physiological phenomena, the word “bio” and “signal” itself can mean any signals that can be found in living beings, also signal is some kind of message which contain informations. The very basic of biosignal assessment is from physiologist or us through observing the condition of the patient as on Fig. 1.1. The signals can be perceived by our senses like seeing in Fig. 1.1, touching as in Fig. 1.2, and hearing as in Fig. 1.3. Moving on to the next topic, where does biosignals come from? Apart from looking through our eyes we can feel vibrations and hear sounds emanating from within the living body. It is said the sources are vital organs which will be discussed on chapter 2. Those sounds and vibrations will travel through the body and perceived by us. It can be illustrated in Fig. 1.4 where they transmit, propagate, and us, receive. Thus this can be mathematically modeled as a block diagram which in the book had a figure as in Fig. 1.5 where there is biosignals source, then goes through propagation, coupling, and conversion loss, finally registration of biogsignal. The figure shows high similarity of Ohm’s law where the generator is in form of voltage “U”, through propagation there is an impedance of “Z” or resistance “R” for direct current (DC) (this one is alternating current (AC)), the registration of biosignal in form of current “I”. On therapy for physiologist, they will first have to learn how biosignals from healthy living being, then tries performing sets of method on the sick patient to return the abnormal biosignals to its healthy state. The therapy model on the book of Fig. 1.6 is more like a control system trying to achieve the desired biosignal, on this case the biosignal of a healthy living being. Outer parts of the body can be observed through sight, but for the inner parts sight is not common to use on the inside of the body conventionally since back then is not possible to see without disemboweling the outer parts. So vibration through touch and sound through hearing is commonly used to observe the inner part. To hear better stethoscope was invented, its ancestors is drawn on Fig. 1.7 and modern one is Fig. 1.1. However the information derived by the physician is highly subjective (different between each physicians) and a standard scale was demanded. It’s very interesting that back then they use musical nodes to document the heart beat rate on Fig. 1.8 before sphygmomanometer were discovered as on Fig. 1.9 which is its ancestor, and today the heartbeat can be drawn as form if sinusoid signals as on Fig. 1.10 which the figure also shows some other biosignals. Today even more tools are demanded for biosignal monitoring as on Fig. 1.11. Base on the book previously data was only known by physicians, but today with more monitoring tools more of patient’s condition can be recorded and documented which can be used for further analysis. The future trend is to make portable wearables where the monitoring doesn’t have to be done in the clinic. Ideally the closer the data to the condition of everyday live the better since the sickness is not represented in the clinic but what happens when the patients do their activities in their respective environment. Research sensor node commonly in how much data that could be retrieved, battery live, and patients’ comfort where wireless is more preferred than wire for example. 2. CellsIn the previous chapter was explained that biosignals from inside of our body, propagates through the skin, and perceived by us with the help of stethoscope. Inside of our bodies can be found different organs with brain, heart, kidneys, liver, and lungs as the major. Each organs have their own functionality and thus may produce different kind of biosignals. However the origin of biosignals is hypothesized to come from even deeper that made up of these organs which are called cells. Thus this summary will only include how cell is related to biosignals. Cell is the smallest unit of life which forms the basics of functions and structures in living things, also represents the origin of any biosignals. There is a basic structure of cells that consists of outer cell, cell contents, and its specialized units, which on Fig. 2.1 shows a illustration of it, but not all cells have the same structure, however shares similarities. The biosignal itself some may call it bioelectricity which is electricity emitted by cells. How does cells produce electricity? In simple term it is created from the potential difference between cells, and/or potential difference between intracellular (inside the cell) and extracellular (outside the cell). When the cells of living things are stimulated, sodium (Na+) and Potassium (K+) ions move rapidly through the cell membrane’s ion channel, creating a difference in electric potential. Sodium can be found outside the cell in form of NaCl (salt) while potassium can be found inside the cell. This also shows that cloride (Cl-) ion can also generate potential difference when flowing. Knowing this the number of nutrients the cells receive affects biosignal generated, with advance knowledge one can determine the condition of a person through biosignal alone. In the previous paragraph it is said that sodium and potassium flows in and out through the membrane channel which in the book showed that the cell membrane played the most important part in generating biosignal or bioelectricity. The membrane isolates the inner of the cell from the outer and controls interaction between cells which attached to similar ones and repels others, also controls interaction with other substances. Fig. 2.2 showed the ion channel controls what is coming in and out, looking at the image the channel is a protein that lines up with lipid molecules with more details on the right image. First the lipid molecules has a hydrophobic (repels water) side and hydrophilic side. They are formed from attraction of molecules between positive and negative charge. Though water (H2O) is an ionic bond that have equal positive and negative charge but the negative part will be attracted to the positive part of the lipid and so on. Second the channel is a protein which is too much of a topic to discuss here, however the protein have five main function in cells which is (1) as a channel, (2) as transporters, (3) as enzymes, (4) as receptors (only channel receptor is dicussed (1) and (2)), and (5) as structural proteins (not discussed). The channel can be passive channel like on Fig 2.2 or an active channel (transporter) on Fig 2.3 which chooses whether it is permeable to sodium, potassium, or whatsoever (only allowing certain ions). The flow of ions on passive channel is due to ions moving from higher concentration to lower concentration (sodium (Na+) comes in and Potassium (K+) comes out), and after certain points there will be equilibrium between concentrations of outside and inside the cell (no more flow) and that’s when the active channel activates. It will draw potassium back inside the cell and releases sodium back outside the cell. Thus the function of active channel is to create a difference in concentration between inside and outside in order for the passive channel to work again. The flow of ions is not only due to difference in concentration but also to chemical bonding. For example the Potassium (K+) is positively charge and outside the cell there is a chloride (Cl-) negatively charge. It can be said that the negatively charge chloride (Cl-) is pulling the Potassium (K+), and this is one of the place that enzymes come into play. The enzymes are more of a helper and accelerator to speed up the chemical bonding mostly in figure aspect as on Fig 2.4 like a key and lock process. Going back to the Fig 2.2 it showed a membrane that has one passive channel, while in actual it can have more active and passive channel, also another channel which will be discussed. But before that, with just the active and passive channel the cell is in a resting state (resting potential) where the flow of ions in and out of the passive channel is stable. Potassium (K+) going out, then going back in because the cell became negatively charged due to lack of positive ions, then going out again due to difference in concentration. When equilibrium is reached the active channel creates a difference in concentration again and everything will restart. This stable state or resting potential calculated on squid axon is about -50mV. The other potential other than the resting potential is the action potential. It is state when the cell flows a large portion of ion generating more potential difference, meaning much more bioelectricity or biosignals. This action potential is triggered when the cell is stimulated, Fig 2.5 shows a model of the axon cell being artificially stimulated, while Fig 2.6 shows how our body really works where the stimulation is sent from our brain, through the neuron, then contracting the muscles. The channel that is responsible for action potential is called gated channel. People studying electronics should see similarity with gated transistors, when a certain voltage is applied to the gate, the flow opens and amplifying the current. Surprisingly the gated channel works in similar way, or maybe the other way around that transistor was modeled after this. On Fig 2.7 the gated channel can either be voltage-gated or transmitter-gated. For voltage-gated like transistor can be stimulated by applying voltage around -55mV (in squid) while the transmitter-gated relies on a substance like a key that activates the channel. On Fig 2.6 the neurons applies voltage and releases these substances. After the action potential state it will return to resting potential state. With more examination the resting and action potential can be modeled into form of electric circuit as on Fig 2.8. My Impression on This ClassMy undergraduate is in electrical engineering in the field of telecommunications but I knew only a little of telecommunications and excels at programming and computer network. Back then I was unfortunate in taking a short electromagnetic wave course that the course was until before maxwell equation which is why I did not know about maxwell equation. In the end I'm very weak on that field and finds it hard to study antennas. Thanks to this masters course I was able to learn more of my field and cover some of my weaknesses. If I could give suggestion of this course, I would suggest the use of computer simulations such as Octave to demonstrate electromagnetic waves and polarization, Splat for RF propagation, or nec2c for antenna design simulation which will make the course more interesting. These are opensource softwares. This assignment except the images has never been published anywhere and I, as the author and copyright holder, license this assignment customized CC-BY-SA where anyone can share, copy, republish, and sell on condition to state my name as the author and notify that the original and open version available here. What is the difference between the LOS and NLOS environment?
What is the merit of using circular polarization in wireless communication and describe examples of applications of circular polarization?
There are many kinds of antennas, why many different kinds of antennas should exist?
DisclaimerThis is not an official guide, not peer reviewed, and does not even take citations but only my opinion based on my experience of 9 years as a student in university. As years passes, experience and knowledge accumulates where this article maybe upgraded in the future. Still, I hope this article can answer to those who asked me of how to make a research plan. I probably made this article based mostly on my dissertation but check out my thesis and final project as well. 1. Choose a FieldYou probably already have a field or major unless you just solely aimed to be accepted in a university only. Well if you are, then you better choose a general field like Computers, Electrical Engineering, Mathematics, Science, Social Science, Agriculture, Politics, Law, Art, Language, etc. For me, I am mostly in Computers, Internet, and Electrical Engineering because I spent most of my time on the computer and the Internet where they cannot function without electricity. 2. Choose an ExpertiseWhat do you want to concentrate on in your field? If you say that you want to focus on electricity, electricity today have many applications. Do you want to do electronics such as with television, refrigerator, air conditioner, etc, or do you want to do electrical power such as with generators and power line transmissions, do you want to do telecommunications where electricity is used to deliver information such as your old phone and new smartphone, or do you want to study electricity as a science? There are many things and as for my field in Computers and Internet and I chose information communication educational technology (ICET). Computers can be for many things such as for calculation, processing, simulation, arts, gaming, etc, also for Internet such as social media, e-commerce, news, entertainment, etc. I chose utilizing Computers and Internet for education. 3. Choose a Research TopicA topic is a discussion that you want to highlight in your concentrated field such the newest power plant, innovation in online payments, latest technology on video games, etc. However a "research" topic starts with a problem. A problem is not always accidents in operations like the power plant exploded and what to do, the Internet traffic got congested so how to solve, or classical math like solve this equation. A problem can be something that we want to do but cannot do such as how to send our other senses through the Internet like touch, smell, and test, how to find specific words mentioned in an audio or video, and how to verify transactions without third party. A problem can also be a desire for improvement such as how to generate more clean electricity daily, how to reduce electricity consumption, how to download a high definition video in less than a second, and how to increase the processing speed of computer processes. I chose a topic of how to capture students' attention and interaction during online learning. 4. Literature ReviewWhile choosing a research topic can be done with minimum general information reading and brainstorming your own idea regarding the problem and solution, but to be accepted as a research, you need to survey how other researchers are doing. If you remained in your workshop connect a single board computer to a graphic processing unit (GPU) card and claimed that you assembled a hand size gaming computer, then ASUS, Dell, and other providers already released a hand size gaming computer that is much faster and much smaller if you do not know. For general audience who did not understand what I said, I will provide another example. You can stay in a cave, assemble a bunch of rechargeable batteries and components and claimed that you build a pocket charger for your phone, but you should realize that you are behind times that many powerbanks are already on the market. Unless you surveyed those products and claimed at least one advantage such as your creations are cheaper. When I surveyed others' research about capturing students' attention and interaction during online learning, I found some tried to improve the conventional method where they use surveys and quizzes, some tried video calls, and some newer methods emerges which are eye tracking and mouse tracking. I decided to go with mouse tracking. Then I gathered any literatures regarding mouse tracking prioritizing ones in the education sector. Where do I do literature reviews? While the conventional library books still works but in modern times, we have more options:
5. State of The ArtState of the art is the goal of literature review which is the most recent stage in the development of a product, incorporating the newest technology, ideas, and features. In other words, what novelty can you contribute? After reading all those literatures, what problems that you found or what issues that others have not highlighted or what ideas that have never emerged before? The quality and quantity of the state of the art determines the quality of the research plan. As for my case about mouse tracking in education:
Writing your Research Plan
NoteThis is a collection of my undergraduate assignments that I translated to English myself in the Basic Electrical Power Engineering course. This assignment has never been published anywhere and I, as the author and copyright holder, license this assignment customized CC-BY-SA where anyone can share, copy, republish, and sell on condition to state my name as the author and notify that the original and open version available here. General Electric Energy Supply ProcessElectrical ConversionConversion in the field of electric power is the conversion from other energy to electrical energy. This conversion is usually used to generate electricity, producing this electricity is called a generator, in other words as a producer. Here are example sources of electrical energy: Hydroelectric Power Plant, Steam Power Plant, Nuclear Power Plant, Gas Power Plant, and Diesel Power Plant. Other generators include: Solar Power, Wind Power, Chemical Reactions, Geothermal Energy and others. Nuclear Energy etc → Reactor Converter etc → Alternate → Transformer Step Up; Reactor Converter etc → Generate Electric TransmissionElectric transmission is the process of sending electricity. The delivery goes through the power grid. Step-Up Transformer → High Voltage Network → Step-Down Transformer → Medium Voltage Network → Factory Electricity DistributionElectricity distribution is the process of sharing electricity to consumers. Medium Voltage Network → Step-Down Transformer → Low Voltage Network → Consumer Basic TheoriesOhm LawOhm law: V=IR, V = voltage (volt), I = current (ampere), R = resistance (ohm). Inverter, Rectifier, UPSTransformatorTransformers are devices for changing the voltage. The step-down transformer lowers the voltage while the step-up transformer increases the voltage. Magnetic FielddH = (IdI x aR)/(4πR2)(A/m), H = ∮(IdI x aR)/(4πR2) I = current (A), dl = length, aR = vector, R = vector length. Magnetic Field Flux B = dΦ/ds = μH, Φ = ∮Bds B = magnetic field flux density (weber/area), Φ=magnetic field flux (weber), ds = area (m2), H = magnetic field strength (A/m) Direct Current Generator Working PrincipleThe working principle of a direct current generator is based on Faraday's law: e = -N dΦ/dt Where, N: number of turns, Φ: magnetic flux, e: induced voltage, emf (electromotive force). The commutator functions as a switch. The commutator is in the form of a split ring attached to the end of the anchor. When the anchor rotates, the ring will rotate. When the coil has rotated half a turn, the brush will close the ring gap so that the voltage becomes zero. Because the ring continues to rotate, the gap will open again and create tension again. If the voltage period is the same as the ring rotation period, the voltage that arises is the full wave direct current voltage. Types of Direct Current Generators Viewed from its Field WindingSelf-Strengthening GeneratorCompoundSome ExercisesIsh = 600V/75Ω = 8A, I = 300000W/600V = 500A, Ia = Ish+I = 8A+500A = 508A ∆Vtotal = ∆V+∆Va = Ia R+Ia Ra = Ia (R+Ra) = 508A(0.03Ω+0.02Ω) = 25.4V emfV = V+∆Vtotal = 600V+20.4V = 625.4V emfP = (emfV)(Ia) = (625.4V)(508A) = 317703.2W 2. Transformer 1ɸ is given a 50 Hz supply step down 2200 V → 250 V with an area of 36 cm2 and a flux density of 6 wb/m2, look for the primary and secondary windings. Known: f = 50 Hz E1 = 2200 V E2 = 250 V A = 0.0036 m2 Bm = 6 wb/m2 Asked: N1 and N2 Answer Φm = (Bm)(A)=(6 wb/m2)(0.0036 m2) = 0.0216 wb E = (4.44)(f)(N)(Φm) = (4.44)(f)(N)(Bm)(A) Primary Winding = E1/((4.44)(f)(Φm)) = 2200/((4.44)(50 Hz)(0.0216 wb)) = 458.79 Secondary Winding = E2/((4.44)(f)(Φm)) = 250/((4.44)(50 Hz)(0.0216 wb)) = 52.135 3. The power of the transformer 1ɸ is 25 KVI, the primary winding is 500, the secondary winding is 50, the primary winding is connected to a voltage of 3000 V with a frequency of 50 Hz. Find the load currents in the primary and secondary winding, secondary emf and maximum flux. (ignore the drop voltage) Known P = 25 VI N1 = 500 N2 = 50 E1 = 3000 V f = 50 Hz Asked I1, I2, E2 and Φm Answer E = (4.44)(f)(N)(Φm) = (4.44)(f)(N)(Bm)(A) Φm = (4.44)(f)(N1)/E1 = (4.44)(50 Hz)(500)/(3000 V) = 37 wb E2/E1 = (4.44)(f)(N2)(Φm)/(4.44)(f)(N1)(Φm) = N2/N1 E2=N2/N1 E1 = 500/50 3000 V = 30000V P=(V)(I) I1 = P/E1 = (25 W)/(3000 V) = 8.3mA I2 = P/E2 = (25 W)/(30000 V) = 0.83mA CatatanIni merupakan kumpulan tugas-tugas S1 saya di mata kuliah Dasar Teknik Tenaga Listrik. Tugas ini tidak pernah dipublikasi dimanapun dan saya sebagai penulis dan pemegang hak cipta melisensi tugas ini customized CC-BY-SA dimana siapa saja boleh membagi, menyalin, mempublikasi ulang, dan menjualnya dengan syarat mencatumkan nama saya sebagai penulis dan memberitahu bahwa versi asli dan terbuka tersedia disini. Proses Pengadaan Energi Listrik Secara UmumKonversi ListrikKonversi dalam bidang tenaga listrik adalah konversi dari energi lain ke energi listrik. Konversi ini biasanya dipakai dalam menghasilkan listrik, penghasil listrik ini disebut pembangkit. Dengan kata lain sebagai produsen. Sebagai sumber energi listrik yang sudah resmi antara lain: PLTA (Pembangkit Listrik Tenaga Air), PLTU (Pembangkit Listrik Tenaga Uap), PLTN (Pembangkit Listrik Tenaga Nuklir), PLTG (Pembangkit Listrik Tenaga Gas), PLTD (Pembangkit Listrik Tenaga Diesel) dan lain-lain. Pembangkit lain antara lain: Tenaga Surya, Tenaga Angin, Reaksi Kimia, Panas Bumi dan lain-lain. Energi Nuklir dll → Converter Reaktor dll → Alternate → Transformator Step Up; Converter Reaktor dll → Generate Transmisi ListrikTransmisi listrik adalah proses pengiriman listrik. Pengiriman melewati jaringan listrik. Transformator Step-Up → Jaringan Tegangan Tinggi → Transformator Step-Down → Jaringan Tegangan Menengah → Pabrik Distribusi ListrikDistribusi listrik adalah proses pembagian listrik kepada konsumen. Jaringan Tegangan Menengah → Transformator Step-Down → Jaringan Tegangan Rendah → Konsumen Teori-Teori DasarHukum OhmHukum ohm: V=IR, V = tegangan (volt), I = arus (ampere), R = hambatan (ohm). Inverter, Rectifier, UPSTrafo (Transformator)Transformator (trafo) adalah alat untuk mengubah tegangan. Trafo step-down menurunkan tegangan sedangan trafo step-up meningkatkan tegangan. Magnetic FielddH = (IdI x aR)/(4πR2)(A/m), H = ∮(IdI x aR)/(4πR2) I = arus (A), dl = panjang, aR = vektor, R = panjang vektor. Flux Medan Magnet B = dΦ/ds = μH, Φ = ∮Bds B = kerapatan flux medan magnet (weber/area), Φ=flux medan magnet (weber), ds = luar area (m2), H = kuat medan magnet (A/m) Prinsip Kerja Generator Arus SearahPrinsip kerja suatu generator arus searah berdasarkan hukum Faraday: e = -N dΦ/dt Dimana, N: jumlah lilitan, Φ: fluksi magnet, e: Tegangan imbas, ggl(gaya gerak listrik). Komutator berfungsi sebagai saklar. Komutator berupa cicin belah yang dipasang pada ujung jangkar. Bila jangkar berputar maka cincin akan berputar. Bila kumparan telah berputar setengah putaran, sikat akan menutup celah cincin sehingga tegangan menjadi nol. Karena cincin berputar terus, maka celah akan terbuka lagi dan timbul tegangan lagi. Bila perioda tegangan sama dengan perioda perputaran cincin, tegangan yang timbul adalah tegangan arus searah gelombang penuh. Jenis-Jenis Generator Arus Searah Dilihat Dari Belitan MedannyaGenerator Penguatan SendiriCompoundSoal-SoalIsh = 600V/75Ω = 8A, I = 300000W/600V = 500A, Ia = Ish+I = 8A+500A = 508A ∆Vtotal = ∆V+∆Va = Ia R+Ia Ra = Ia (R+Ra) = 508A(0.03Ω+0.02Ω) = 25.4V emfV = V+∆Vtotal = 600V+20.4V = 625.4V emfP = (emfV)(Ia) = (625.4V)(508A) = 317703.2W 2. Trafo 1ɸ diberikan supply 50 Hz step down 2200 V→250 V dengan luas 36 cm2 dan kerapatn fluks 6 wb/m2, carilah belitan primer dan sekunder. Diketahui: f = 50 Hz E1 = 2200 V E2 = 250 V A = 0.0036 m2 Bm = 6 wb/m2 Ditanya: N1 dan N2 Jawab Φm = (Bm)(A)=(6 wb/m2)(0.0036 m2) = 0.0216 wb E = (4.44)(f)(N)(Φm) = (4.44)(f)(N)(Bm)(A) belitan primer = E1/((4.44)(f)(Φm)) = 2200/((4.44)(50 Hz)(0.0216 wb)) = 458.79 belitan sekunder = E2/((4.44)(f)(Φm)) = 250/((4.44)(50 Hz)(0.0216 wb)) = 52.135 3. Daya trafo 1ɸ adalah 25 KVI, belitan primer adalah 500, belitan sekunder adalah 50, belitan primer dihubungkan dengan tegangan 3000 V dengan frekuensi 50 Hz. Carilah arus beban pada belitan primer dan sekunder, emf sekunder dan fluks maksimal. (abaikan drop voltage) Diketahui P = 25 VI N1 = 500 N2 = 50 E1 = 3000 V f = 50 Hz Ditanya I1, I2, E2 dan Φm Jawab E = (4.44)(f)(N)(Φm) = (4.44)(f)(N)(Bm)(A) Φm = (4.44)(f)(N1)/E1 = (4.44)(50 Hz)(500)/(3000 V) = 37 wb E2/E1 = (4.44)(f)(N2)(Φm)/(4.44)(f)(N1)(Φm) = N2/N1 E2=N2/N1 E1 = 500/50 3000 V = 30000V P=(V)(I) I1 = P/E1 = (25 W)/(3000 V) = 8.3mA I2 = P/E2 = (25 W)/(30000 V) = 0.83mA |
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