Acoustics is the science concerned with the production, control, transmission, reception, and effects of sound.
Its origins began with the study of mechanical vibrations and the radiation of these vibrations through mechanical waves, and still continues today.
Research was done to look into the many aspects of the fundamental physical processes involved in waves and sound and into possible applications of these processes in modern life.
The study of sound waves also lead to physical principles that can be applied to the study of all waves. Applications of acoustic technology include music and the study of geologic, atmospheric, and underwater phenomena.
Psychoacoustics, the study of the physical effects of sound on biological systems, has been of interest since Pythagoras first heard the sounds of vibrating strings and of hammers hitting anvils in the 6th century BC, but the application of modern ultrasonic technology has only recently provided some of the most exciting developments in medicine.
The ear itself is another biological instrument dedicated to receiving certain wave vibrations and interpreting them as sound..
Saturday, July 24, 2010
Bluetooth Technology
Introduction To Bluetooth Technology
Bluetooth technology is a radio frequency short range communications technology that was created with the intention of replacing wired cables that are used to connect various portable and fixed devices. The use of this technology will do away with the physical cables that connect devices. The key features are its low cost, low power and robustness in maintaining high level of security.
Bluetooth was made possible by the Bluetooth Special Interest Group(SIG) which was founded by Ericsson, IBM, Intel, Nokia and Toshiba in the year 1998. The objective was to develop an open specifications for short range wireless connectivity. More than 1900 companies have since joined the SIG and the numbers are increasing day by day.
Specifications
The specifications provide developers the link layer and application layer definitions which are used to support both voice and data applications. The spectrum of frequency used is in the unlicensed ISM(Industrial, Scientific and Medical) band at 2.4 Ghz to 2.485 GHz using spread spectrum and frequency hopping. As this is a free band, there is no cost for the use of Bluetooth compared to cellular phones where one must subscribe to use the network of GSM or CDMA.
IEEE 802.15.1 standard is used in the development of Bluetooth enabled products. The versions used are Ver 1.2 with data rate of 1 Mbps and ver 2.0 with data rate of up to 3 Mbps. The range of operation depends on the device classes. They are:
Class 3 – 1 meter range with maximum permitted power set at 1mW.Class 2 – 10 meters range with maximum permitted power set at 2.5mW. Class 1 – 100 meters range with maximum permitted power set at 5mW.
Bluetooth technology is a radio frequency short range communications technology that was created with the intention of replacing wired cables that are used to connect various portable and fixed devices. The use of this technology will do away with the physical cables that connect devices. The key features are its low cost, low power and robustness in maintaining high level of security.
Bluetooth was made possible by the Bluetooth Special Interest Group(SIG) which was founded by Ericsson, IBM, Intel, Nokia and Toshiba in the year 1998. The objective was to develop an open specifications for short range wireless connectivity. More than 1900 companies have since joined the SIG and the numbers are increasing day by day.
Specifications
The specifications provide developers the link layer and application layer definitions which are used to support both voice and data applications. The spectrum of frequency used is in the unlicensed ISM(Industrial, Scientific and Medical) band at 2.4 Ghz to 2.485 GHz using spread spectrum and frequency hopping. As this is a free band, there is no cost for the use of Bluetooth compared to cellular phones where one must subscribe to use the network of GSM or CDMA.
IEEE 802.15.1 standard is used in the development of Bluetooth enabled products. The versions used are Ver 1.2 with data rate of 1 Mbps and ver 2.0 with data rate of up to 3 Mbps. The range of operation depends on the device classes. They are:
Class 3 – 1 meter range with maximum permitted power set at 1mW.Class 2 – 10 meters range with maximum permitted power set at 2.5mW. Class 1 – 100 meters range with maximum permitted power set at 5mW.
Simple DC Motor Driver
This simple DC motor driver circuit uses a 741 operational amplifier operating as a voltage follower where its non inverting input is connected to the speed and rotation direction of a potentiometer VR1. When VR1 is at mid position, the op-amp output is near zero and both Q1 and Q2 is OFF.
When VR1 is turned towards the positive supply side, the output will go positive voltage and Q1 will supply the current to the motor and Q2 will be OFF. When VR1 is turned to the negative supply side, the op-amp output switches to the negative voltage and Q1 will turn OFF and Q2 ON which reverses the rotation of the motor's direction.
As the potentiometer VR1 is moved toward either end, the speed increases in whichever direction it is turning.
The TIP3055 Q1 NPN power transistor has a collector current specs of 15A and VCE0 of 60V DC.
The MJE34 Q2 PNP power transistor has a collector current specs of 10A and VCE0 of 40V DC.
When VR1 is turned towards the positive supply side, the output will go positive voltage and Q1 will supply the current to the motor and Q2 will be OFF. When VR1 is turned to the negative supply side, the op-amp output switches to the negative voltage and Q1 will turn OFF and Q2 ON which reverses the rotation of the motor's direction.
As the potentiometer VR1 is moved toward either end, the speed increases in whichever direction it is turning.
The TIP3055 Q1 NPN power transistor has a collector current specs of 15A and VCE0 of 60V DC.
The MJE34 Q2 PNP power transistor has a collector current specs of 10A and VCE0 of 40V DC.
Acupuncture
Acupuncture is one of the main branches of Traditional Chinese Medicine
The technique involves the insertion of needles into "acupuncture points" on the body by trained practitioners.
According to acupunctural teachings this will restore health and well-being, and is particularly good at treating pain.
The definition and characterization of these points is standardized by the World Health Organization.
Acupuncture is thought to have originated in China and is most commonly associated with Traditional Chinese medicine.
Other types of acupuncture (Japanese, Korean, and classical Chinese acupuncture) are practiced and taught throughout the world.
Scientists have conducted reviews of existing clinical trials according to the protocols of evidence-based medicine; some have found efficacy for headache, low back pain and nausea, but for most conditions have concluded that there is insufficient evidence to determine whether or not acupuncture is effective.
The technique involves the insertion of needles into "acupuncture points" on the body by trained practitioners.
According to acupunctural teachings this will restore health and well-being, and is particularly good at treating pain.
The definition and characterization of these points is standardized by the World Health Organization.
Acupuncture is thought to have originated in China and is most commonly associated with Traditional Chinese medicine.
Other types of acupuncture (Japanese, Korean, and classical Chinese acupuncture) are practiced and taught throughout the world.
Scientists have conducted reviews of existing clinical trials according to the protocols of evidence-based medicine; some have found efficacy for headache, low back pain and nausea, but for most conditions have concluded that there is insufficient evidence to determine whether or not acupuncture is effective.
How diamonds form underground?
Ask anybody about why a diamond is so special, and you will get the standard replies about the beauty, price, and exclusiveness of these unique gems. In reality, it is those features that make diamonds so appealing, but the true power of these elemental masterpieces comes from how they are made and how they are brought to the surface of the Earth. It is cool stuff indeed!While the science behind diamonds is impressive, it would not be as important if not for the more mainstream qualities that garner such high respect for diamonds. After all, there are many substances that are formed through interesting scientific processes, but unless there is actual use to what is produced, that doesn't mean much, except to scientific eggheads in their grand Universities.The chemical composition of a diamond is exactly the same as what you use in your pencil or the coal we burn for energy. A diamond is simply carbon, nothing else. Of course, there is a little more to it than just that. The carbon in diamonds is compressed at extremely high depths in the surface of the Earth, and in addition to the massive pressure, there is also a high temperature. The combination enables the carbon to be intensely concentrated, so much so that the resulting output is the hardest mineral in existence. It is impossible to cut a diamond, except with powerful lasers. It cannot even be broken with a bullet.In order for diamonds to be brought to the surface, they must go through something called a diatreme. This is a volcano-like structure in which deep minerals are shot up at supersonic speeds! While this has never been witnessed by humans, as diatremes became inactive millions of years ago, we know about them based on scientific observation, experimentation, and extrapolation.
Clever cats use mimicry when hunting
In a fascinating example of vocal mimicry, researchers have documented for the first time a margay wild cat (Leopardus wiedii) imitating the call of its intended victim: a small, squirrel-sized monkey known as a pied tamarin (Saguinus bicolor).
The extraordinary behavior was recorded by researchers from the Wildlife Conservation Society (WCS) and Federal University of Amazonas (UFAM) in the Amazonian forests of Brazil. The observations confirmed what until now had been only anecdotal reports from Amazonian inhabitants of wild cat species - including jaguars and pumas - mimicking primates and other species in order to draw them within striking range.
"Cats are known for their physical agility, but this vocal manipulation of prey species indicates a psychological cunning which merits further study," reported WCS researcher Fabio Rohe in the current issue of Neotropical Primates.
Researchers observed the trickery when a group of eight pied tamarins were feeding in a ficus tree. They then observed a margay emitting calls similar to those made by tamarin babies. This attracted the attention of a tamarin "sentinel," which climbed down from the tree to investigate the sounds coming from a tangle of vines called lianas
The extraordinary behavior was recorded by researchers from the Wildlife Conservation Society (WCS) and Federal University of Amazonas (UFAM) in the Amazonian forests of Brazil. The observations confirmed what until now had been only anecdotal reports from Amazonian inhabitants of wild cat species - including jaguars and pumas - mimicking primates and other species in order to draw them within striking range.
"Cats are known for their physical agility, but this vocal manipulation of prey species indicates a psychological cunning which merits further study," reported WCS researcher Fabio Rohe in the current issue of Neotropical Primates.
Researchers observed the trickery when a group of eight pied tamarins were feeding in a ficus tree. They then observed a margay emitting calls similar to those made by tamarin babies. This attracted the attention of a tamarin "sentinel," which climbed down from the tree to investigate the sounds coming from a tangle of vines called lianas
cyber lock system
CyberLock is an access control system that increases key control and accountability throughout your organization. Based on a unique design of electronic lock cylinders and intelligent keys, CyberLock solves security problems that no other system can.
CyberLock cylinders replace standard mechanical lock cylinders. Cylinders install without wiring, easily converting your existing lock hardware into an access control system.
This concept of electronic cylinders means there are CyberLock solutions for much more than just doorways. For customers large and small, CyberLocks secure cabinets, cash boxes, trucks, gates, narcotic boxes, safes, vending machines, cell tower sites, traffic control boxes, server cabinets—and, yes, doors—around the world.
CyberKeys are programmed by the software with the access permissions for each user. Keys work only during specific hours, and only for the locks each person is allowed access to. Because these intelligent keys restrict access and cannot be duplicated, the need to re-key a facility is eliminated.
Each time a key is used, a record of that event is stored in the key and the cylinder, for later transfer to the management software. For convenience, this information transfer can be done securely in a variety of ways, either at the computer where the software is being accessed or from remote locations. The data gathered is a valuable tool to better understand workplace efficiencies and areas of possible risk.
And, there’s management software to meet the needs of every user: small-to medium-sized businesses to large campus
CyberLock cylinders replace standard mechanical lock cylinders. Cylinders install without wiring, easily converting your existing lock hardware into an access control system.
This concept of electronic cylinders means there are CyberLock solutions for much more than just doorways. For customers large and small, CyberLocks secure cabinets, cash boxes, trucks, gates, narcotic boxes, safes, vending machines, cell tower sites, traffic control boxes, server cabinets—and, yes, doors—around the world.
CyberKeys are programmed by the software with the access permissions for each user. Keys work only during specific hours, and only for the locks each person is allowed access to. Because these intelligent keys restrict access and cannot be duplicated, the need to re-key a facility is eliminated.
Each time a key is used, a record of that event is stored in the key and the cylinder, for later transfer to the management software. For convenience, this information transfer can be done securely in a variety of ways, either at the computer where the software is being accessed or from remote locations. The data gathered is a valuable tool to better understand workplace efficiencies and areas of possible risk.
And, there’s management software to meet the needs of every user: small-to medium-sized businesses to large campus
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