STELLA

STELLA SIMULATION

Introduction.

            Simulation is one of the technique that teacher can use to increase students interest toward the topic. It is also a useful technique that can illustrate a complex and changing situation. If teachers choose simulation as the teaching technique, they need computer stimulation as teaching tools. Computer simulation is the discipline of designing a model of an actual or theoretical physical system, executing the model on a digital computer, and analyzing the execution output. The principle of simulation is “learning by doing” which means the learner acts, the stimulation reacts and the learner from this feedback.

 Before we learn about the system, we must first build the model and then operate the model. The model that being build must be related and relevant to the topic and also can be handling by teachers and students. Simulation also can be used to provide the students with the fertile learning environment. By doing this, teachers can trigger students interest about the topic and also they can become more active during the class.

Simulation can be used as an activity that closely related to student like students who role plays. Students especially students learn by using simulating like toys. When teacher used abstract teaching tools, students are more excited because they can see more clearly about the topic.  To make students more understand the reality and the complexity about the topic that being teach, teachers must build some artificial object that can be use as teaching tools. Teacher can also act out roles with students while teaching especially when explaining the complex system like respiration for human and also excretion in human body. Computer simulation can be use as electronic equivalent of this type of role playing and also serves to drive synthetic environment and virtual worlds.

When planning to create the simulation there are three primary sub-field that should be taking into consideration. The first one is model design followed by model execution and lastly model analysis. In order to build the simulation model, we must first design the model by create a mathematical model which represents that physical object. The models can take many form like functional and multimodel which the model contain multiple integrated models each of which represents a level of granularity for the physical systems. After that, the model that has being design will be execute the model on a computer that needs computer program. The last sub-field that need to be complete while create the simulation is model analysis. This last stage will go through the model that have being create whether it practical or do not practical. Model analysis is also need to find any mistake about the simulation model so that when it is being used during teaching and learning process, there is no error when the data is collected.

 As being mention before, simulation is closely related to computer and the compute also a great source for simulation educational activities. Simulation as also known as virtual reality, this term implies all things to all people. There is a lot of basic material and application that available in the computer that teachers can use as simulation. There are three ways that we can the computer for simulation activities.

First, run a simulation program on a computer. This is very simple but yet very effective. There are a lot of simulations inside a computer, for example Microsoft Office Excel. This software can be use to collect data, tabulate the data and also present the data in a form of various types of graph and chart. Students can change the data, so that they can see the result and also the change in pattern of the graph. By this way, students can predict the outcome if they change some of the variables but, this software only limited to number variables only. Second, use the simulation on the World Wide Web (WWW). There is a lot of simulation in the internet nowadays. What a teachers need to do is just spent some time to explore the internet to find the suitable simulation that can be used when teaching. Do not afraid to explore the internet and try different simulation, understand the application and then choose the simulation that can be handled easily and also practical. The third way that we can use is by enhance the simulation with computer. Many of the simulation that you run can be enhanced by using computer. To add reality to the simulation, the computer can be used to display the images and pictures. The computer can make the pictures or images more real. Simulation or virtual reality does not have to be complex but simple.

Some people will get confuse whether simulation is a games or not. There is a lot of differences between simulation and games. Games create competition but simulation not. Simulation is used to help the process of teaching and learning in the class. Simulations also illustrate relationship and create insights and also allow people to practice behaviours. Since simulation do not create any competition it will make the users practise the positive behaviour like patient. Games only focus on the attention on extrinsic motivation (gamification) but simulation focus attention on intrinsic motivation. Extrinsic motivation is the motivation that come from outside of an individual, rewards like money or grades and these reward provide satisfaction that the game or task itself may not provide. Intrinsic motivation is the motivation that comes from inside of the individual like the pleasure one get from the task itself or the sense of satisfaction when completing the task or work. 

As a teacher, we need to make sure that the students learn something from the simulation. For the students learn something from the simulation, teacher must do the discussion during the simulation or after the simulation and teacher can do both session. This is very important as an integral to the student’s learning. There are here phases that can be use to make sure that this simulation can be done smoothly during the class. The phases are orientation, the simulation and debrief.

For the first phase which is orientation, teacher will give briefing and explanation to the students about what the simulations are about and for. Teacher must fully describe the simulation so that students can fully understand the concepts of the simulation. Other than that, teacher also has to ensure the students completely understand the purpose of the simulation. If the simulation needs rule or any safety precaution, make sure to outline it for the students. Write the rules or the safety precaution on the board so that the students can apply it during the do the simulation.

The second phase is the simulation, where the students will do the simulation. Teacher will monitor the students to make sure that they can work properly with the simulation and also can cooperate well with the other students. Guide the students during this session so that the students can get familiar with the simulation and also try to relate the simulation with the topic that students should learn that day. Simulation can also give other benefits to students for example good moral values. Every time in the class, teacher must include moral values.

The last phase that should be taken when using simulation is debrief. In the end of the simulation, there is always part discussion. At this part student will do their reflection on what they have learn when using the simulation. There is much different method or strategy that can be done by teacher when doing debrief. One of the ways is, by group the students into small group of 5 or 4 students. Then, each group will be given one learning objective for the simulation. The group will discuss about the learning objectives and also the teacher will give another question about what the students think about the simulation. Each group then will present to the class. Comment from the students then can be use to make improvement for the simulation. 

Result:

Graph 1:

          

Graph 2:

Graph 3:

 Graph 4:

Discussion:    

In an ecosystem, there is always an interaction between organisms. That is the nature of this world. Some people might think that it is cruel to kill other organism but, if some animal do not kill other animal, they will not survive. There are a lot of interaction between organism in this earth like mutualism, parasitism and prey-predator interaction. In this graph, we will discuss more about the interaction between prey and predator.

            A predator is the organism that eats another organism while prey is the organism that predator eats. All four graphs above show the interaction between predators (lynx) and prey (hares). Lynx is the type of wild cat. Hares may be looks like rabbit but they are not from rabbit family. Hares have 48 chromosomes while rabbit only 44 chromosomes. As being mention before, the interaction between lynx and hares is prey predator. We will see the pattern of the interaction in the graph above.  

            For graph 1, it shows that the number of lynx and hares is stable throughout the years. This means that there is no environmental complexility in the ecosystem. The number of lynx is balance with the number of hare. The birth rate of hares can afford the needed from lynx. That is why from the graph we can see that the interaction between the predator and prey is constant throughout the year. There is no increasing or decreasing number for both predator and prey.

            For graph 2, it shows that the size of 1 time lynx harvest is increasing as the number of hares increase. At the beginning of the graph, the lynx is drop a little bit as the hares constant. This is because when the number of hares becomes constant for such a long time, the number of lynx will decrease because there is no food for them. If the food source decreases, the competition between predators will become tight. There is no increasing in food source so the predator will die thus the shows the decreasing in number. The following pattern shows that the increasing of food source for predator (lynx) which is prey (hares) will simultaneously increase the number of predator.  

            For graph 3, compared to graph 2 the number of both prey (hares) and predator (predator) is slightly increase. The concept is still same as is mention at graph 2. Graph 4 also shows the same pattern with tremendously increasing number of both lynx and hares. This shows that the lynx have enough food supply from the increasing number of hare.

            The conclusion that we can make from the relation between prey and predator is when the prey is numerous their predators increase in numbers this then will reducing the prey population which then make the number of predator to decreases. After sometimes, the relation is expected to recover and starting a new cycle. According to the recent research, the predator and prey systems are potentially unstable because predators often extinguish their prey and then starve. In nature, there is at least three factors that can promote stability and coexistence.   

All of the graph shows above is one of the example of simulation. From the graph itself we can see that by using the simulation the learning and teaching process will become more interesting and effective. There is a lot of benefits that teacher can get by using simulation as one of their teaching tools. Simulations are low cost to create than the real life counterparts. Simulation is also easy to use and less risky. Other than that simulation can be repeated over and over again whereas real life cannot.

To the students, using the simulation can give them motivation. This motivation will develop when using the simulation. The motivation that students will get is they will highly anticipate learning more about the topic. The most important things when using teaching tools, teacher must choose the one that can increase student interest and simulation is one of the best choices. When students involve in the activity they will be interested to learn more about the activity and also the subject or topic.

Simulations are “hands-on” that involve students. Students will become participants not just a listener or observers. Students observe and learn more from their own experiences than having other’s experience related to them. They will experience on how to do their own experiment that related to the topic. Since simulation is “hands-on”, students will explore the topic by playing with the simulation. By doing this, students can relate the topic with the simulation and see clearly the concept behind the topic. Simulation stimulate an activity that is “real” ,this means that simulation are “virtually real”. The purpose why simulation is being create is because they stimulate activity that are similar with the real situation and environment. From this creation, students can learn the real experience.

Simulation is tailored to the students. Simulation is designed specifically for students the user and they take development improvement into consideration. This means that, when simulation is developed, the students will be the user and from time to time there is always be an improvement that can be made. This is the advantage of simulation where we can improve the model from time to time. This improvement will produce better simulation model that can be use by students and teacher. The developing of simulation also considered students development level. Slow students will use simple simulation while high develop students will use more complex simulation but yet easy to handle. This is not a bias to anyone but, simulation that being use must suit with the development level of the students. Suitable simulation is very important to make sure that students can learn something from the simulation.

Using simulation will increase student’s interest to learn more about the topic. Since students will experience their own experiments, they will find that the topic that being taught is really interesting. Students are more excited when being introduce to something new. When teacher first introduce simulation in the class, students at first will feel burden because they are not familiar with the concept and functional of simulation. After sometimes and a lot of practices, students will get familiar with the simulation and thus become more excited to learn. Simulation is also empowering. This is because, students are given a chance to be responsible, find ways to succeed and also they will develop problem solving tools as a result of the interaction with the simulation.

Simulation can encourage student to do more prediction like what scientist always do. Simulation model will have parameter that can be change and adjust by users. This application allow user to predict what will happen if they change some parameter. Students that use this simulation can predict what will happen to the experiment or task that they are doing if they change the parameter. Students can also add other adjustable parameter. The try and error method will help students to understand more about the topic. In the real situation, it is impossible to change any parameter and also see the result immediately. Just like in the example above, the prey-predator interaction. It is impossible to see the interaction pattern of predator (lynx) when we decrease or increase the number of prey (hares) because in the real situation it takes many years to see the pattern. By using simulation, students can predict on the pattern outcome when we increase or decrease the number of hare and see the pattern result for both prey and hares immediately.   

In conclusion, the traditional method of teaching should change because students nowadays are totally different from 20 years ago. Simulation is one of the new teaching method that teacher can use nowadays. Teacher role nowadays also different from before, they are not only give knowledge to students but also guide them. Simulations give new dimension to the learning experience and develop the teacher’s role even further. Students also will experience new method of learning.

Reference:

1.      http://www.slideshare.net/enspirelearning/how-simulations-can-change-the-future-of-learning

2.      http://www.creativeteachingsite.com/edusims.html

3.      http://www.creativeteachingsite.com/virtual.htm

4.      http://www.usask.ca/education/coursework/mcvittiej/methods/simul.html

5.      http://www.cise.ufl.edu/~fishwick/introsim/node1.html

6.      http://www.globalchange.umich.edu/globalchange1/current/lectures/predation/predation.html

Data Logging (Essay)

Data logging: Speed Of Sound

INTRODUCTION

Data logger is an electronics instrument that records measurements of all types at set intervals over a period of time. Data logger also can record a wide variety of energy and environmental measurements including temperature, speed, light intensity, pressure, electric currents and more. The characteristic of a data logger is the ability to take sensor measurements and store the data for future used. This is how data logger works, a data logger works with sensors that then will convert physical phenomena and stimuli into electronic signals such as voltage or current. These electronics signals are then converted or digitized into binary data. The binary data is then easily analyzed by software and stored on a PC hard drive or other form of storage like memory card and CDs.

While we talking about data logger, data logging is the process of using a computer to collect data through sensors, analyze the data and save and output the results of the collection and analysis. Data logging is also implies the control of how the computer collects and analyzes the data. It is commonly used in scientific experiments and in monitoring systems where there is the need to collect the information faster than we do it manually especially when the experiments need accuracy. Figure below shows the complete data logging applications elements. 

A data logger has an additional recording and storage facilities. It can store readings from events taking days or week to unfold. Afterwards, the computer can read the data from it. There stand alone devices can often record data at high speed for example they can record the flicker of a lamp and take 100’s of readings in second. The data logger has buttons to start and stop according as well as an independent power supply. The buttons allow us to alter the recording speed when the recording would start. The data logger may have an LCD display to monitor what it is doing. In nearly every system that find, data logging sensors plug into a box. The sensor send its ‘readings’ to the box and informs it which type of sensor it is. The sensor identifies itself using pins on the sensor plug while some systems place a resistor across the pins and use its value to identify it. Others sensor have a PIC chip which ‘tells’ the data logger all it needs to know. Some sensors have their own power supply but the best derive all their power via the interface. Some devices get all their power through a USB connection o Parallel port and these tend to be the most reliable. The interface box has a circuit that converts an analogue sensor signal to a digital signal. It also has a way communicating with the computer and most systems use ‘serial’ communication. Serial connections are compatible with almost every type of computer. While this is not fast communication, they transfer data fast enough for most purposes. If we want to show sound waves with these data loggers, we can record the sound at high speed and transfer the data to the computer afterwards. Data logger can collect readings independently of the computer, allows results collected in the lab to be downloaded to the lab computer, can be set to start recording during the night, record very fast, can be set to start recording at a certain sensor reading and can store the results of many experiments. Data logger has a rechargeable battery and uses alkaline batteries.

In every PC data logging and controls system, there are few basic components which are sensors, connectors, conditioning, Analog to Digital (A/D) Conversions, Online-Analysis, Logging/Storage, and Offline-Analysis. A few additional components also required in a dta logging and Control system including D/A Conversions and actuators.

Sensors

There are many type of sensors that are used in data logging. Sensors often process data before we can see it. The types of sensors that have are sensors to measure motion. Sensors that used to measure motion are accelerometer, light gates and switches, force or dynamic or mechanic pulley, rotation sensor, shock sensor, sonar distance sensor or ranger and strain gauge. The sensors that used to measure heat and temperature are heat flow sensor, full range temperature sensor, low temperature sensor, body temperature range sensor and thermocouple and high temperature sensors. Sensors for light and sound, we used light sensor, calorimeter sensor, infra-red sensor, sound sensor, microphone sensor, sound switch sensor and ultra-violet sensor. Sensors that used in physiology are pressure sensor, breathing monitor sensor, heart rate sensor and electrocardiogram sensor.

Any device that is used to convert physical parameters into electrical signals is called sensors. The sensors must be calibrated so that electrical output they provide maybe used to take meaningful measurements. For examples, flow meters, pressure transducers, accelerometers and microphone.  After we have the sensors, it must be connected to the connectors to transmit its electrical signal to the systems. There are variety of signal connectors that each have their own advantages and disadvantages. The simple connectors can be as simple as tightening a screw around a wire to the more complex like connectors typically used in NDT shown below.

Conditioning is the next steps needed for the electrical signal provided by the sensor to be useful. It is including all actions performed on the signal to improve its usability before it is digitized. There are few types of conditioning that can be used. Amplification is used when the voltage levels being measured are very small. Amplification is used to maximize the effectiveness of the digitizer. The typical sensors that require amplification are the thermocouples and strain gauges. Attenuation is the reverse of the amplification and necessary for measuring the high voltages. Filtering is the required to remove unwanted frequency components from a signal that will prevents the aliasing and reduces noise.

Excitation is used to provide the required currents and can be voltage or current source depending on the sensor type. Linearization is a type of sensors produce voltage signals that are not linearly related to the physical quantity they measuring. Isolation is used to in conjunction with attenuation to protect the system and the user from dangerous voltages or voltage spikes. It also can be used to when the sensor is on a different electrical ground plane from the measurement sensor. Lastly, multiplexing. Multiplexing allows you to automatically route multiple signals into a single digitizer. Most of the sensors required the combination of two or more of this conditioning technique like thermocouple.

There is also other components that build the data logging systems like A/D conversion that convert analog electrical signal into digital values and transmit those signal to the computer and these is done by the using the data acquisition (DAQ) board. Online analysis is used after the analog signal has been converted to raw binary values. For logging or storage ,PC based data logging systems generally use the hard drive of the PC to store data, but may also use tape drivers, network drivers, or RAID drivers. After that, offline analysis is the performing mathematical analysis on data after it has been acquired to extract information. There are two forms of control part of the PC system. The first one is open – loop control which is independent of the current state of the process and the second one is the closed-loop control in which the PC measures one or more input variables and uses software to make decisions about what control signals should be output. Other than that, there is also D/A converter which the function is to takes the digital values output by the computer and turns them into analog signals which can be conditioned and then connected to actuators. Actuators is any device that converts electrical signals to physical parameters. 

 People we ask why we use data logging. Data logging help us do a lot of things. Data logging help us to perform the experiments in a short time. If we do a manual experiments, we will take time to construct the apparatus, adjust the parameters, collect the data and to analysis the data. By using the data logging, we also can perform the experiments online and also perform the online analysis. For online analysis, this step will include any analysis that we could like to do before storing the data. The most basic example is, when converting the voltage measurements to meaningful scientific units, such as degree Celsius. We can complete these complex calculations and data compressions before logging the data. Controlling part of a system based on current measurements. Every data-logging software applications have to complete the conversions from binary to voltage and the conversions from voltage to scientific units. 

There is also step in data logging which is log that refers to the storage of analyzed data including any formatting required for the data files. When doing the experiment, it is very important to save all the data from the experiment, therefore by doing data logging, we can save all the data that need to be analyzed and also the format. Other than that, data logging also help you to do the offline analysis. Offline analysis is the analysis that we do after storing the data. For example, we can use the data stored to look for trends in historical data or data reduction.

Data logging also will help us by displaying, sharing and reporting the experiment that had be done. This application can save our time and also the experiment can be repeated over again to get the result that we need. This does not means the data logging application will prepare for you the full report of the experiment like the full writing report but it can help you to create any reports that need to make present the data. Data logging also can present the data straight from the online analysis. This means that the monitor able to display the data you need and also analyzed the data and also viewing the historical data.

 DATA LOGGING : SPEED OF SOUND

Engage :

  

Last weekend, my family decide to go to Gua Kelam in Perlis. As we walk through the cave there is a lot of nice things to watch. Then, I notice something interesting, when we talk in the cave, we can hear our voice be reflect. We hear our own voice echo. Why this happened? I also notice the same phenomena occur when I talk in empty house or when I shout in the tunnel. How can this happen and what is the cause?

The speed of sound is the distance travelled during a unit of time by a sound wave propagating through an elastic medium. In dry air at 20 °C, the speed of sound is 343.2 metres per second. In fluid dynamics, the speed of sound in a fluid medium either gas or liquid is used as a relative measure of speed itself. The speed of an object (in distance per time) divided by the speed of sound in the fluid called the Mach number.

The speed of sound in an ideal gas depends on frequency, but it is weakly depends on frequency for all real physical situations. Sound speed depends on pressure only because the air is not quite an ideal gas. For different gases, the speed of sound is inversely dependent on square root of the mean molecular weight of the gas, and affected to a lesser extent by the number of ways in which the molecules of the gas can store heat from compression, since sound in gases is one type of compression.

Speed of sound refers to the speed of sound waves in air and the speed of sound varies from substance to substance. Sound travels faster in liquids and non-porous solids compared in air. It travels about 4.3 times as fast in water, and nearly 15 times as fast in iron. Sound waves in solids are composed of compression waves just as in gases and liquids, but also exhibit a different type of sound wave called a shear wave, which occurs only in solids. The different types of waves in solids usually travel at different speeds. The speed of a compression sound wave in solids is determined by the medium's compressibility, shear modulus and density.

Sound is a longitudinal wave that is created by a vibrating object, such as a guitar string, the human vocal cords or the diaphragm of a loudspeaker. Moreover, sound can be created or transmitted only in a medium, such as a gas, liquid and solid. To see how sound waves are produced and why they are longitudinal, consider the vibrating diaphragm of a loudspeaker. When the diaphragm moves outward, it compresses the air directly in front of it. The compression causes the air pressure to rise slightly. The region of increased pressure is called condensation, and it travels away from the speaker at a speed of sound. The condensation is analogous to the compressed region of coils in a longitudinal wave.

Sound travels through gases, liquids and solids at considerably different speeds as shown in the table below:

Substance	Speed (m/s)
Gases Air(0º C ) Air (20º C ) Carbon dioxide (0ºC ) Oxygen (0º C ) Helium (0º C )	331 343 259 316 965
liquids Chloroform (20º C ) Ethyl alcohol (20º C ) Mercury (20 º C ) Fresh water (20º C ) Seawater (20º C )	1004 1162 1450 1482 1522
Solids Copper Glass (Pyrex ) Lead Steel	5010 5640 1960 5960

Near room temperature, the speed of sound in air is 343 m/s and is markedly greater in liquids and solid. For example, sound travels more than four times faster in water and more than seventeen times faster in steel than it does in air. In general, sound travels slowest in gases, faster in liquids and fastest in solids. Like the speed of a wave on a guitar string, the speed of sound depends on the properties of the medium. In a gas, it is only when the molecules collide that the condensations and rarefactions of a sound wave can move from the place to other place. It is reasonable, then, to expect the speed of sound in a gas to have the same order of magnitude as the average molecular speed between collisions. Sonar is a technique for determining water depth and locating underwater objects, such as reefs, submarines, and schools of fish. The core of a sonar unit consists of an ultrasonic sound, and at a later time the reflected pulse returns and is detected by the receiver. The water depth is determined from the electronically measured round-trip time of the pulse and a knowledge of the speed of sound in water. In a liquid, the speed of sound depends on the density and the adiabatic bulk modulus. For the speed of sound in liquid for example in seawater, the speed is 1522 m/s, which is more than four times as great as the speed in air. The speed of sound is an important parameter in the measurement  of distance. Accurate distance measurements using ultrasonic sound also play an important role in medicine where the sound often travels through liquid-like materials in the body. A routine preoperative procedure in cataract surgery, for example, uses an ultrasonic probe called an A-scan to measure length of the eyeball between the lens of the eye and the retina. When sound travels through a long, slender, solid bar, the speed of the sound depends on the properties of the medium.

Empower :

Ø  Equipment required

v  2 microphones-crystal Mics were used since they are cheap and give a large output

v  1 metre wooden rule

v  Fast digital storage oscilloscope-the ADC-212 was used

v  A balloon-to burst for a sudden loud sound source

Ø  Experiment set up

The experiment was set up as shown below with two crystal microphones placed 1 metre apart.

RESULT:

·         The balloon was burst approximately 2 m away from the foremost Mic. The plot below shows the results clearly.

—  The lefthand “BLUE” trace is from the foremost Mic (Mic1) and the righthand “red” trace is from Mic (Mic2)

—  The waveform from Mic1 between -164µs and 500 s is clearly visible in the trace from Mic2 delayed by 2929 µs. There is second variation , in the waveform from Mic1, around 1.5 ms caused by an echo  from one  wall or ceiling. 

Enhance :

—  Telling how far away a person with a starter’s gun, at a running race, is by comparing the time difference from when you can see the gun’s smoke to when you hear the sound.

—  Telling how far away a cliff is by making a sound and measuring how long it takes for the echo to return

—  Telling where an enemies gun was fired.

—  Telling  how far away a lighting strike.

REFERENCES :

—   http://www.ni.com/white-paper/2946/en

—                        http://www.ndt-ed.org/GeneralResources/DataLogging/DataLogging.htm

—  http://www.onsetcomp.com/what-is-a-data-logger

—  http://www.webopedia.com/TERM/D/data_logging.html

   —  John D. Cutnell and Kenneth W.  Johnson  (2010). Introduction to Physics. Asia : Wiley.

—  Roger Frost. Data Logging in Practice. United Kingdom : IT in Science Publishing.

Data Logging (Slide Presentation)

Data logging final!! from Fazreena Ma'amor