Wednesday, April 4, 2007
I have to admit we had a nice trip on a nice weekend morning. The trip was held in American Museum of Natural History. Last time I was here is 1994, when I was 13 years old.
Teacher Jamie kindly introduce us another gentleman, Dean, who work for the museum, as a one day tour guide for us. One interesting point Dean mentioned is that we cannot put textbooks on the wall and force visitors to take them all words by words. As a solution, we use a way through design to attract people's eye and try to stimulate them, and see if we can rise their interest about the subject we display.
2. Interesting Displaying Design
a) touch screen interface
This is called Tree of Life, which author use a 3D tree object to demonstrate the various creatures' life within and related to a tree. Good thing about it is user can have a broad view about different lives on the tree, and can have detail review of specific one if he click into it.
I and my classmate were talking about if we can grab certain creatures from the tree into a box, a introduction box which give you detail information of your selection , that would be more attractive and create more fun feeling with this system.
This is another touch screen demonstration system which tells you about the differences of brain and nerves system between human and chimpanzee.
Something I like about this system if the buttons lie in the lower right corner. If you only click on human, it will show you the detail of human body structure, such as human brain. But if you click on both human and chimpanzee, it will show you the comparison of brains of human and chimpanzee.
In the exhibition we find some interesting box that display certain amount of small object. I specially love the graphic design as the picture beside. You can see the designer emphasize the number to attract visitor's eye, and it really got me.
c) Round Table
Jamie was like King Arthur, and we all stand surrounding the round table, carefully listen to his instruction. It's interesting that we talked and shared opinion around the table, which reminds me a Chinese traditional dining situation: a big family sitting around a big round table and sharing food, feeling, and emotion. (Obviously we don't wanna share those bones on the demonstrate table)
The table fascinate me because there's the other one designed in opposite way, which is text content placed inside, and physical object outside on the table.
d) Screen projection box
Like in movies, there's a 3D projected image!! In a small box demonstrating people's behaviors like using tools. The designer successfully use a dark box with some thin transparent sheet and a hidden projector located below to simulate the 3D projection.
3. Shop for working, not for shopping
After visiting the exhibiting area, Jamie told us to go to the shop. I was wondering why we have to go to a souvenir shop on this trip? In the end it's a workshop to create animal model, not for selling souvenir.
We discovered how they create those fake animals and plants, by using all kind of artificial materials and sometimes real one like leather. Just like making a movie, they try to recreate those creatures as real as possible which really fascinate me.
Tuesday, March 20, 2007
Why do we need to know body fat?
Everybody cares about his own health condition, to see if he or she is in a good shape. Weigh is an easy-getting information that shows you if you're out of shape. However, counting on weight only is too risky because it doesn't show you how much fat you have which is the main factor causing heart disease. Too much fat, obesity, is definitely neither good looking nor healthy.
Nowadays we have mainly two ways (regardless of those non-mainstream ways)to know how much body fat one has. First, the luxury way, is to go to some hospitals or health centers, spending a lot of money to let those professional immerse you in a water tank and measure very detail displacement of your body fat. The other way is to buy a cheap body fat monitor from stores and measure your self anytime you want to.
Body fat monitor often uses a technology called "Bioelectrical Impedance Analysis"(BIA) which measures the impedance to an electrical signal in your body which might be seen as the level of obesity. Actually it shots an non-harmful electron into one side or your body(e.g. your left foot) and receive it from the other side(e.g. your right foot). It measures how much the loss of electron is between the start point and the end, and then translate this number of loss into degree or percentage of body fat degree and show it on the screen.
For men, your age & body fat percentage diagram:
The theory of electron loss is a hypothesis that while electron travels through the water found in muscle and fat, the more muscle a person has, the more water their body can hold. The greater the amount of water in a person's body, the easier it is for the current to pass through it. In contrast, the more fat, the more resistance to the current. The factors that go into determining the percentage of body fat include a person's weight, height, age, gender and body type.
For women, your age & body fat percentage diagram:
How to use a body fat monitor:
Before using the scale for the first time you enter your age, gender, height. Weight is displayed on the LCD screen and five seconds later your percentage of body fat appears. Usually you will get higher body fat value in the morning than evening because after a sleep the food you consumed at daytime already transform into body fat.
Typical Body Fat Monitor
The one I have in hand is made by Tanita, the company who claims to be the world leader in precision electronic scales. Tanita's device looks like a normal bathroom scale, using 4 normal AA batteries as power supply.
To be written...
Pads(shot and receive electron)
To be written...
To be written...
Wednesday, February 14, 2007
Programmable Linear Hall-Effect Sensors
A hall effect sensor is a transducer that varies its output voltage in response to changes in magnetic field density. If an electric current flows through a conductor in a magnetic field, the magnetic field exerts a transverse force on the moving charge carriers which tends to push them to one side of the conductor. This is most evident in a thin flat conductor as illustrated.
A buildup of charge at the sides of the conductors will balance this magnetic influence, producing a measurable voltage between the two sides of the conductor.
Hall Effect Sensor:
* type: A1373EKB-T (programmable Linear Hall-Effect Sensor)
* manufacturer: Allegro Micro System Inc.
Supply Voltage: 16 V
Reverse Supply Voltage: –16 V
Output Voltage: 16 V
Reverse-Output Voltage: –0.1 V
Output Source Current: 3 mA
Output Sink Current : 10 mA
Operating Ambient Temperature: Range E –40 to 85 oC, Range L –40 to 150 oC
Maximum Junction Temperature: 165 oC
Storage Temperature: –65 to 170 oC
Key Features Computing Core
* Output pin programming
* Field-programmable for optimal application integration
* Selectable coarse and fine gain and quiescent output voltage
* Selectable sensitivity temperature coefficient
* Selectable output clamp voltage level, including no-clamp (rail-to-rail)
* Selectable output polarity
* Unipolar or bipolar operation
* Ratiometric sensitivity, clamps, and quiescent output voltage
* Chopper-stabilized Hall technique
* Wide operating temperature range
* On-chip regulator for over/under voltage protection
* On-chip regulator provides EMI robustness
* Wide lead-spacing with KB package
This device incorporates a chopper-stabilized amplifier, voltage regulator, programming logic, and an output amplifier on a single IC. The patented dynamic offset cancellation used with a chopper-stabilization technique provides low offset and minimal temperature drift. A high frequency clock is used for chopping, to ensure high frequency signal processing capability.
The design and manufacturing flexibility of the A1373 is emphasized by offering programmable gain, quiescent offset voltage for unipolar or bipolar operation, temperature coefficient, clamps, and polarity. The device can be set up in a magnetic circuit and programmed with a train of serial pulses via the output pin. Once the right combination of gain, quiescent output voltage, and temperature coefficient has been selected, the codes can be locked for one-time programming. In this manner, manufacturing tolerances can be reduced and the assembly process can be simplified.
Hall sensors are used for proximity switching, positioning, speed detection, and current sensing applications. For its accuracy and reliability, its application includes automotive and indtustrial linear position-sensing,such as:
* throttle position sensors
* pedal position sensors
* suspension height sensors
1) What is the [chopper-stabilized amplifier]?
2)What is [no-clamp (rail-to-rail)]?
3) What is the diagram below telling?
Wednesday, February 7, 2007
I made a series of flex sensors, tuck 4 of them into a bendable transparent plastic tube:
And then I hooked these sensors on Arduino board, and use processing code from Jamie Allen, to generate waveform diagram of the sensor value, which change by time if you bend the tube filled with flex sensors.
The result of bending diagram:
[ extend reading about Magic DJ]
Wednesday, January 31, 2007
I was in a tour going to flushing from New York City to Flushing, Queens, (close to Shea Stadium as the place of American Open and NY Mets) where a lot of Chinese people live in. We drove a car, heading Chinese mall with Chinese market and food court to buy Chinese snack and enjoy a big meal.
On the way to Flushing, I take some time playing with all the marvelous device originally installed on vehicle. In the central console, I saw the air conditioning system which include a thermo sensor, to detect the temperature inside the car, and command the other part of air conditioning system to adjust the temperature to the one set by passenger. the thermo sensor is installed below the indoor back mirror, where the height is not far from the height of passengers head, which is a reasonable height setting. The air conditioning system work well on the trip and supposedly the sensor work well as well.
The second sensor I found on the car is the anti-pinch window sensor. While you press the button to lift up the window in order to close it, the anti-pinch function would be activated to detect if the window closing process counter any resistant. If the resistant is a little bit to high, obviously there is potential risk, a possibility that passenger's body might be pinched and then cause injury. So if the resistant is higher than certain level, it would be seen that the closing process is dangerous and the process would automatically stop the closing process and go backward to the open status. Some funny guy use a banana to test if the anti pinch function work well, but certainly we don't use that way in an official testing.
One more sensor was found in the car, which is an weight sensor, to detect the weight of passenger in order to modify the car seat position for two reasons:
First, safety reason, concerns the size of passenger to determine the suitable timing of airbag explosion. If the passenger is in a big size, the timing of explosion would be faster, not to let the heat to burn passenger's face. Second, comfort reason, in some luxury car is designed to fit different size of passengers to give them a better support cushion of the seat.
Going to outside of the car, you might easily find the distance sensors on the rear bumper, which is part of the parking assistance system. Those distance sensors would measure the distance from your vehicle to the obstacle behind, and send a signal to the buzzer in your car to remind you that you're too close something in behind.
Another sensor could be found outside the car is the rain drop sensor. In some cars, they have the rain drop sensor, which means if it start raining, the sensor would command the wiper to clean up your wind shield.
The last one I wanna talk about is the anti dazzling light sensor. We know sometimes there is some dazzling light in your back mirror from the car behind you, and make you dazzled and cannot clearly observe the situation of your behind. With the help from anti dazzling sensor, it would detect the dazzling light and change the angle of back mirror to eliminate the driver's
blind spot for safety concern.
Sensors I found:
1. anti-pin window sensor
2. AC thermo sensor
3. distance sensor
4. raindrop sensor
5. anti spotlight sensor
6. weight sensor
See some other sensors in your car: http://images.google.com/imgres?imgurl=http://www.sae.org/automag/techbriefs_04-00/images/02b.jpg&imgrefurl=http://www.sae.org/automag/techbriefs_04-00/02.htm&amp;amp;amp;amp;amp;amp;amp;amp;h=236&w=250&sz=20&hl=en&sig2=vdKqq7JAEiQRLVFAqwwHHQ&start=91&tbnid=SrSaTZ_B58Kr-M:&tbnh=105&amp;amp;amp;amp;amp;amp;amp;amp;tbnw=111&ei=w-TARbGGN4WMggTpjZyUCA&prev=/images%3Fq%3Dpassenger%2Bweight%2Bsensor%26start%3D80%26ndsp%3D20%26svnum%3D10%26hl%3Den%26client%3Dfirefox-a%26rls%3Dorg.mozilla:en-US:official%26sa%3DN