The predecessor of the spacemouse was the DLR controller ball. Spacemouse has its origins in the late seventies when the DLR (German Aerospace Research Establishment) started research in its robotics and system dynamics division on devices with six degrees of freedom (6 dof) for controlling robot grippers in Cartesian space. The basic principle behind its construction is mechatronics engineering and the multisensory concept. The spacemouse has different modes of operation in which it can also be used as a two-dimensional mouse.

How does computer mouse work?
Mice first broke onto the public stage with the introduction of the Apple Macintosh in 1984, and since then they have helped to completely redefine the way we use computers. Every day of your computing life, you reach out for your mouse whenever you want to move your cursor or activate something. Your mouse senses your motion and your clicks and sends them to the computer so it can respond appropriately

2.1 Inside a Mouse
The main goal of any mouse is to translate the motion of your hand into signals that the computer can use. Almost all mice today do the translation using five components:

1. A ball inside the mouse touches the desktop and rolls when the mouse moves.

2. Two rollers inside the mouse touch the ball. One of the rollers is oriented so that it detects motion in the X direction, and the other is oriented 90 degrees to the first roller so it detects motion in the Y direction. When the ball rotates, one or both of these rollers rotate as well. The following image shows the two white rollers on this mouse:

3. The rollers each connect to a shaft, and the shaft spins a disk with holes in it. When a roller rolls, its shaft and disk spin. The following image shows the disk:

4. On either side of the disk there is an infrared LED and an infrared sensor. The holes in the disk break the beam of light coming from theLED so that the infrared sensor sees pulses of light. The rate of the pulsing is directly related to the speed of the mouse and the distance it travels.

5. An on-board processor chip reads the pulses from the infrared sensors and turns them into binary data that the computer can understand. The chip sends the binary data to the computer through the mouse’s cord.

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The VISNAV system uses a Position Sensitive Diode (PSD) sensor for 6 DOF estimation. Output current from the PSD sensor determines the azimuth and elevation of the light source with respect to the sensor. By having four or more light source called beacons in the target frame at known positions the six degree of freedom data associated with the sensor is calculated.

The beacon channel separation and demodulation are done on a fixed point digital signal processor (DSP) Texas Instruments TMS320C55x [2] using digital down conversion, synchronous detection and multirate signal processing techniques. The demodulated sensor currents due to each beacon are communicated to a floating point DSP Texas Instruments TMS320VC33 [2] for subsequent navigation solution by the use of colinearity equations.

Among other competitive systems [3]  a differential global positioning system (GPS) is limited to midrange accuracies, lower bandwidth, and requires complex infrastructures. The sensor systems based on differential GPS are also limited by geometric dilution of precision, multipath errors, receiver errors, etc.These limitations can be overcome by using the DSP embedded VISNAV system.

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The goal of steganography is to hide messages inside other “harmless” messages in a way that does not allow any “enemy” to even detect that there is a second secret message present. The only missing information for the “enemy” is the short easily exchangeable random number sequence, the secret key, without the secret key, the “enemy” should not have the slightest chance of even becoming suspicious that on an observed communication channel, hidden communication might take place.

Steganography is closely related to the problem of “hidden channels” n secure operating system design, a term which refers to all communication paths that cannot easily be restricted by access control mechanisms. In an ideal world we would all be able to sent openly encrypted mail or files to each other with no fear of reprisals. However there are often cases when this is possible, either because the working company does not allow encrypted email or the local government does not approve of encrypt communication (a reality in some parts of the world). This is where steganography can come into play.

Data hiding techniques can also be classified with respect to the extraction process:
Cover Escrow methods need both the original piece of information and the   encoded one in order to extract the embedded data.Blind or Oblivious schemes can recover the hidden message by means only of the encoded data.

Steganography has developed a lot in recent years, because digital techniques allow new ways of hiding informations inside other informations, and this can be valuable in a lot of situations. The first to employ hidden communications techniques -with radio transmissions- were the armies, because of the strategic importance of secure communication and the need to conceal the source as much as possible.
Nowadays, new constraints in using strong encryption for messages are added by international laws, so if two peers want to use it, they can resort in hiding the communication into casual looking data. This problem has become more and more important just in these days, after the international Wassenaar agreement, with which around thirty of the major – with respect to technology – countries in the world decided to apply restrictions in cryptography export similar to the US’s ones.

Another application of steganography is the protection of sensitive data. A file system can be hidden in random looking files in a hard disk, needing a key to extract the original files. This can protect from physical attacks to people in order to get their passwords, because maybe the attacker can’t even know that some files are in that disk.

The major concern of steganography is stealth, because if an attacker, either passive or active, can detect the presence of the message, from that point he can try to extract it and, if encrypted, to decrypt it. The resistance to attempt at destruction or noise is not required, since we consider the sender and the receiver equally interested in exchanging messages, so that they will try to transmit the stego-medium in the best way they can. If the stego-data can be transmitted over the selected channel, and this is usually the case with all the media that are used, like images or sounds, then the embedded data will be preserved along with them. Thus, data hiding techniques for steganography must focus on the maximum strength against detection and extraction.

As a second request, we would prefer a high data rate, because we will usually want to be able to exchange any amount of data, from simple messages to top secret images.

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By the 1970s, computers grew fast enough to process an average user’s applications. But, they continued to occupy considerable amount of space as they were made of solid blocks of iron. The input was done by means of punch cards, and later came the keyboard, which revolutionalized the market. In 1971 came the 4004, a computer that was finally small in size. The programmability of these systems were quite less. Still, computers had to be plugged directly in to AC outlets, and input and output done by punch cards.  These computers were not built keeping users in mind. In fact, the user had to adjust himself with the computer.

This was the time when wearable computer (wearcomp) was born. In the 1970s, wearcomp challenged the other PCs with its capability to run on batteries. Wearcomps were a new vision of how computing should be done. Wearable computing showed that man and machine were no more separate concepts, but rather a symbiosis. The wearcomps could become a true extension of one’s mind and body.

In the beginning of 1980s, personal computing emerged. IBM’s PC and other cheaper clones spread world-wide like fire. Finally the idea of a small PC on your desktop that costed you quite less became a reality. In the late 1980s PC’s introduced the concept of WIMP (Windows, Icons, Mice & Pointers) to the world which revolutionalised the interface techniques. At the same time, wearables went through a transformation of their own. They were now eyeglass based, with external eyeglass mounts. Though they remained visible to all, wearcomps were developing principles of miniaturization, extension of man’s mind and body, secrecy and personal empowerment. Now, the only thing needed was an environment for them to flourish. People began to realize that wearcomps could be a powerful weapon in the hands of an individual against the machinery.
The 1990s witnessed the launch of laptops. The concept was a huge success as people could carry their PC wherever they go, and use them any time they need. A problem remained still.  They still had to find a workspace to use their laptops since keyboards and mice (or touch-pads) remained.

During all these years of fast transformation, there remained visionaries who struggled to design computers that were extension of one’s personality, computers that would work with your body, computers that will be with you at all times, always at your disposal. In the last two decades, wearcomps grew smaller still. Now you have completely covert systems which would reside inside your average glasses.

One of the prevalent ideas in wearable computing is the concept of mediated reality. Mediated reality refers to encapsulation of the user’s senses by incorporating the computer with the user’s perceptive mechanisms, which are used to process the outside stimuli. For example, one can mediate their vision by applying a computer-controlled camera to enhance it. The primary activity of mediated reality is direct interaction with the computer, which means that computer is “in charge” of processing and presenting the reality to the user. A subset of mediated reality is augmented reality. It differs from the former because interaction with the computer is secondary. The computer must be able to operate in the background, providing enough resources to enhance but not replace the user’s primary experience of reality. Wearable computers have many applications centered around this concept of mediated / augmented reality as well as many other exciting applications centered around the idea of immediate access to information.

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Speech morphing can be achieved by transforming the signal’s representation from the acoustic waveform obtained by sampling of the analog signal, with which many people are familiar with, to another representation. To prepare the signal for the transformation, it is split into a number of ‘frames’ – sections of the waveform. The transformation is then applied to each frame of the signal. This provides another way of viewing the signal information. The new representation (said to be in the frequency domain) describes the average energy present at each frequency band.

Further analysis enables two pieces of information to be obtained: pitch information and the overall envelope of the sound. A key element in the morphing is the manipulation of the pitch information. If two signals with different pitches were simply cross-faded it is highly likely that two separate sounds will be heard. This occurs because the signal will have two distinct pitches causing the auditory system to perceive two different objects. A successful morph must exhibit a smoothly changing pitch throughout. The pitch information of each sound is compared to provide the best match between the two signals’ pitches. To do this match, the signals are stretched and compressed so that important sections of each signal match in time. The interpolation of the two sounds can then be performed which creates the intermediate sounds in the morph. The final stage is then to convert the frames back into a normal waveform.

However, after the morphing has been performed, the legacy of the earlier analysis becomes apparent. The conversion of the sound to a representation in which the pitch and spectral envelope can be separated loses some information. Therefore, this information has to be re-estimated for the morphed sound. This process obtains an acoustic waveform, which can then be stored or listened to.

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Since it is proteins, and to a much lesser extent, other types of biological molecules that are directly involved in both normal and disease-associated biochemical processes, a more complete understanding of the disease may be gained by directly looking at the proteins present within a diseased cell or tissue and this is achieved through the study of the proteome, Proteomics. For, Proteomics, we need 2-D electrophoresis equipment ot separate the proteins, mass spectrometry to identify them and x-ray crystallography to know more of the structure and function of the proteins. These equipments are essential in the study of proteomics.

Genomics has provided a vast amount of information linking gene activity with disease. It is now recognized that gene sequence information and pattern of gene activity in a cell do not provide a complete and accurate profile of a protein’s abundance or its final structure and state of activity.

The day of spotlight of the human genome is now coming to an end. Researchers are now concentrating on the human proteome, the collective body of all the proteins made by a person’s cells and tissues. The genome- the full set of information in the body-contains only the recipes for making proteins; it is the proteins that constitute the bricks and mortar of cells and that do most of the work. Moreover it is the proteins that distinguish the various types of cells: although all cells have essentially the same genome, they can vary in which genes are active and thus in which proteins are made. Likewise diseased cells often produce proteins that healthy cells don’t and vice versa.

Proteome research permits the discovery of new protein markers for diagnostic purposes and of novel molecular targets for drug discovery.

All living things contain proteins. The structure of a cell is largely built of proteins. Proteins are complex, three-dimensional substances composed of one or more long, folded polypeptide chains. These chains, in turn, consist of small chemical units called amino acids. There are twenty kinds of amino acids involved in protein production, and any number of them may be linked in any order to form the polypeptide chain.

The order of the amino acids in the polypeptide chain is decided by the information contained in DNA structure of the cell’s genes. Following this translation, most proteins are chemically changed through post-translation modification (PTM), mainly through the addition of carbohydrate and phosphate groups. Such modification plays an important role in modulating the function of many proteins but the genes do not code it.

As a consequence, the information from a single gene can encode as many as fifty different protein species. It is clear that genomic information often does not provide an accurate profile of protein abundance, structure and activity.

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Optical networks are widely regarded as the ultimate solution to the bandwidth needs of future communication systems. Optical fiber links deployed between nodes are capable to carry terabits of information but the electronic switching at the nodes limit the bandwidth of a network. Optical switches at the nodes will overcome this limitation. With  their improved efficiency and lower costs, Optical switches provide the key to both manage the new capacity Dense Wavelength Division Multiplexing (DWDM) links as well as gain a competitive advantage for provision of new band width hungry services. However, in an optically switched network the challenge lies in overcoming signal impairment and network related parameters. Let us discuss the present status, advantages and challenges and future trends in optical  switches.

OPTICAL FIBERS

A fiber consists of a glass core and a surrounding layer called the cladding. The core and cladding have carefully chosen indices of refraction to ensure that the photos propagating in the core are always reflected at the interface of the cladding. The only way the light can enter and escape is through the ends of the fiber. A transmitter either alight emitting diode or a laser sends electronic data that have been converted to photons over the fiber at a wavelength of between 1,200 and 1,600 nanometers.

Today fibers are pure enough that a light signal can travel for about 80 kilometers without the need for amplification. But at some point the signal still needs to be boosted. Electronics for amplitude signal were replaced by stretches of fiber infused with ions of the rare-earth erbium. When these erbium-doped fibers were zapped by a pump laser, the excited ions could revive a fading signal. They restore a signal without any optical to electronic conversion and can do so for very high speed signals sending tens of gigabits a second. Most importantly they can boost the power of many wavelengths simultaneously.

Now to increase information rate, as many wavelengths as possible are jammed down a fiber, with a wavelength carrying as much data as possible. The technology that does this has a name-dense wavelength division multiplexing (DWDM ) – that is a paragon of technospeak.

Switches are needed to route the digital flow to its ultimate destination. The enormous bit conduits will flounder if the light streams are routed using conventional electronic switches, which require a multi-terabit signal to be converted into hundreds of lower-speed electronic signals. Finally, switched signals would have to be reconverted to photons and reaggregated into light channels that are then sent out through a designated output fiber.

The cost and complexity of electronic switching prompted to find a means of redirecting either individual wavelengths or the   entire light signal in a fiber from one path way to another without the opto-electronic conversion.

OPTICAL SWITCHES

Optical switches will switch a wavelength or an entire fiber-form one pathway to another, leaving the data-carrying packets in a signal untouched. An electronic signal from electronic processor will set the switch in the right position so that it directs an incoming fiber – or wavelengths within that fiber- to a given output fiber. But none of the wavelengths will be converted to electrons for processing.

Optical switching may eventually make obsolete existing lightwave technologies based on the ubiquitous SONET (Synchronous Optical Network) communications standard, which relies on electronics for conversion and processing of individual packets. In tandem with the gradual withering away of Asynchronous Transfer Mode (ATM), another phone company standard for packaging information.

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With short circuit capabilities of power systems getting larger, and the voltage levels going higher the conventional current transformers becomes  more and more bulky and costly also the saturation of the iron core under fault current and the low frequency response make it difficult to obtain accurate current signals under power system transient conditions. In addition to the concerns, with the computer control techniques and digital protection devices being introduced  into power systems, the conventional current transformers have caused further difficulties, as they are likely to introduce electro-magnetic interference through the ground loop into the digital systems. This has required the use of an auxiliary current transformer or optical isolator to avoid such problems.

It appears that the newly emerged Magneto-optical current transformer technology provides a solution for many of the above mentioned problems. The MOCT measures the electric current by means of Faraday Effect, which was first observed by Michael Faraday 150 years ago. The Faraday Effect is the phenomenon that the orientation of polarized light rotates under the influence of the magnetic fields and the rotation angle is proportional to the strength of the magnetic field component in the direction of optical path.

The MOCT measures the rotation angle caused by the magnetic field and converts it into a signal of few volts proportional to the electric currant. It consist of a sensor head located near the current carrying conductor, an electronic signal processing unit and fiber optical cables linking to these two parts. The sensor head consist of only optical component such as fiber optical cables, lenses, polarizers, glass prisms, mirrors etc. the signal is brought down by fiber optical cables to the signal processing unit and there is no need to use the metallic wires to transfer the signal. Therefore the insulation structure of an MOCT is simpler than that of a conventional current transformer, and there is no risk of fire or explosion by the MOCT. In addition to the insulation benefits, a MOCT is able to provide high immunity to electromagnetic interferences, wider frequency response, large dynamic range and low outputs which are compatible with the inputs of analog to digital converters. They are ideal for the interference between power systems and computer systems. And there is a growing interest in using MOCTs to measure the electric currents.

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The LRR calibration circuits consist of partly unknown standards, where L symbolizes a line element and R represents a symmetrical reflection standard. The calibration circuits are all of equal mechanical length. The obstacle, a symmetrical-reciprocal network is placed at three consecutive positions. The network consists of reflections, which might show a transmission. The calibration structures can be realized very easily as etched structures in microstrip technology.

During the calibration [G], [H], which represents the systematic errors of the VNA is eliminated in order to determine the unknown line and obstacle parameters.

Microwave devices are devices operating with a signal frequency range of 1-300GHz. A microwave circuit ordinarily consists of several microwave devices connected in some way to achieve the desired transmission of a microwave signal.

The various microwave solid state devices are,

* Tunnel diodes
These are also known as Esaki diodes. It is a specially made PN junction device which exhibits negative resistance over part of the forward bias characteristic. Both the P and the N regions are heavily doped. The tunneling effect is a majority carrier effect and is very fast. It is useful for oscillation and amplification purposes. Because of the thin junction and shot transit time, it is useful for microwave applications in fast switching circuits.

* Transferred electron devices
These are all two terminal negative resistance solid state devices which has no PN junction. Gunn diode is one of the transferred electron devices and which works with the principle that there will be periodic fluctuations in the current passing through an n-type GaAs substrate when the applied voltage increases a critical value i.e. 2-4Kv/cm.

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SAP AG was found in 1972 by four former IBM employees. Since its foundation, SAP has made significant development and marketing efforts on standard application software, being a global market player with its R/2 system for mainframe applications and its R/3 system for open client/server technologies.

The company name SAP stands for Systems, Applications and Products in Data Processing. It is a standard software package that can be configured in multiple areas and adapted to specific needs of the company. To support those needs, SAP includes large number of business functions, leaving room for further enhancements or adaptability to business practice changes.

ABAP/4 is the $GL (fourth-generation programming language) in which all R/3 applications (the upper layer) are developed. Middleware are the layered software components that facilitate the development of client/server applications that can be deployed in heterogeneous vendor platforms. The basis system, also known as kernel, is the SAP R/3 middleware.

The upper layer, the functional layer, contains the different business applications: financial, human resources, sales and distribution, materials management, and so on. The integration of all applications relies on the basis system.

The R/3 kernel makes use of standard communications and application program interfaces to access the operating system, the database, and the network. This architecture allows users to change system configuration and install new systems without interrupting or altering the applications themselves.

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