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Adaptive Optics in Ground Based Telescopes

Adaptive optics is a new technology which is being used now a days in ground based telescopes to remove atmospheric tremor and thus provide a clearer and brighter view of stars seen through ground based telescopes. Without using this system, the images obtained through telescopes on earth are seen to be blurred, which is caused by the turbulent mixing of air at different temperatures.

Adaptive optics in effect removes this atmospheric tremor. It brings together the latest in computers, material science, electronic detectors, and digital control in a system that warps and bends a mirror in a telescope to counteract, in real time the atmospheric distortion.

The advance promises to let ground based telescopes reach their fundamental limits of resolution and sensitivity, out performing space based telescopes and ushering in a new era in optical astronomy. Finally, with this technology, it will be possible to see gas-giant type planets in nearby solar systems in our Milky Way galaxy. Although about 100 such planets have been discovered in recent years, all were detected through indirect means, such as the gravitational effects on their parent stars, and none has actually been detected directly.

WHAT IS ADAPTIVE OPTICS ?

Adaptive optics refers to optical systems which adapt to compensate for optical effects introduced by the medium between the object and its image. In theory a telescope's resolving power is directly proportional to the diameter of its primary light gathering lens or mirror. But in practice , images from large telescopes are blurred to a resolution no better than would be seen through a 20 cm aperture with no atmospheric blurring. At scientifically important infrared wavelengths, atmospheric turbulence degrades resolution by at least a factor of 10.

Space telescopes avoid problems with the atmosphere, but they are enormously expensive and the limit on aperture size of telescopes is quite restrictive. The Hubble Space telescope, the world's largest telescope in orbit , has an aperture of only 2.4 metres, while terrestrial telescopes can have a diameter four times that size.

ANN for misuse detection

Because of the increasing dependence which companies and government agencies have on their computer networks the importance of protecting these systems from attack is critical. A single intrusion of a computer network can result in the loss or unauthorized utilization or modification of large amounts of data and cause users to question the reliability of all of the information on the network. There are numerous methods of responding to a network intrusion, but they all require the accurate and timely identification of the attack.

Intrusion Detection Systems

The timely and accurate detection of computer and network system intrusions has always been an elusive goal for system administrators and information security researchers. The individual creativity of attackers, the wide range of computer hardware and operating systems, and the ever changing nature of the overall threat to target systems have contributed to the difficulty in effectively identifying intrusions. While the complexities of host computers already made intrusion detection a difficult endeavor, the increasing prevalence of distributed network-based systems and insecure networks such as the Internet has greatly increased the need for intrusion detection.

There are two general categories of attacks which intrusion detection technologies attempt to identify - anomaly detection and misuse detection .Anomaly detection identifies activities that vary from established patterns for users, or groups of users. Anomaly detection typically involves the creation of knowledge bases that contain the profiles of the monitored activities.

The second general approach to intrusion detection is misuse detection. This technique involves the comparison of a user's activities with the known behaviors of attackers attempting to penetrate a system. While anomaly detection typically utilizes threshold monitoring to indicate when a certain established metric has been reached, misuse detection techniques frequently utilize a rule-based approach. When applied to misuse detection, the rules become scenarios for network attacks. The intrusion detection mechanism identifies a potential attack if a user's activities are found to be consistent with the established rules. The use of comprehensive rules is critical in the application of expert systems for intrusion detection.

Current approaches to intrusion detection systems

Most current approaches to the process of detecting intrusions utilize some form of rule-based analysis. Rule-Based analysis relies on sets of predefined rules that are provided by an administrator, automatically created by the system, or both. Expert systems are the most common form of rule-based intrusion detection approaches. The early intrusion detection research efforts realized the inefficiency of any approach that required a manual review of a system audit trail. While the information necessary to identify attacks was believed to be present within the voluminous audit data, an effective review of the material required the use of an automated system.

The use of expert system techniques in intrusion detection mechanisms was a significant milestone in the development of effective and practical detection-based information security systems.

An expert system consists of a set of rules that encode the knowledge of a human "expert". These rules are used by the system to make conclusions about the security-related data from the intrusion detection system. Expert systems permit the incorporation of an extensive amount of human experience into a computer application that then utilizes that knowledge to identify activities that match the defined characteristics of misuse and attack.

Anthropomorphic Robot hand

This paper presents an anthropomorphic robot hand called the Gifu hand II, which has a thumb and four fingers, all the
joints of which are driven by servomotors built into the fingers and the palm. The thumb has four joints with four-degrees-of-freedom (DOF); the other fingers have four joints with 3-DOF; and two axes of the joints near the palm cross orthogonally at one point, as is the case in the human hand. The Gifu hand II can be equipped with
six-axes force sensor at each fingertip and a developed distributed tactile sensor with 624 detecting points on its surface. The design concepts and the specifications of the Gifu hand II, the basic characteristics of the tactile sensor, and the pressure distributions at the time of object grasping are described and discussed herein. Our results demonstrate that the Gifu hand II has a high potential to perform dexterous object manipulations like the human hand.

INTRODUCTION

IT IS HIGHLY expected that forthcoming humanoid robots will execute various complicated tasks via communication with a human user. The humanoid robots will be equipped with anthropomorphic multifingered hands very much like the human hand. We call this a humanoid hand robot. Humanoid hand robots will eventually supplant human labor in the execution of intricate and dangerous tasks in areas such as manufacturing, space, the seabed, and so on. Further, the anthropomorphic hand will be provided as a prosthetic application for handicapped individuals.

Many multifingered robot hands (e.g., the Stanford-JPL hand by Salisbury et al. [1], the Utah/MIT hand by Jacobsen et al. [2], the JPL four-fingered hand by Jau [3], and the Anthrobot hand by Kyriakopoulos et al. [4]) have been developed. These robot hands are driven by actuators that are located in a place remote from the robot hand frame and connected by tendon cables. The elasticity of the tendon cable causes inaccurate joint angle control, and the long wiring of tendon cables may obstruct the robot motion when the hand is attached to the tip of the robot arm. Moreover, these hands have been problematic commercial products, particularly in terms of maintenance, due to their mechanical complexity.

To solve these problems, robot hands in which the actuators are built into the hand (e.g., the Belgrade/USC hand by Venkataraman et al. [5], the Omni hand by Rosheim [6], the NTU hand by Lin et al. [7], and the DLR's hand by Liu et al. [8]) have been developed. However, these hands present a problem in that their movement is unlike that of the human hand because the number of fingers and the number of joints in the fingers are insufficient. Recently, many reports on the use of the tactile sensor [9]-[13] have been presented, all of which attempted to realize adequate object manipulation involving contact with the finger and palm. The development of the hand, which combines a 6-axial force sensor attached at the fingertip and a distributed tactile sensor mounted on the hand surface, has been slight.

Our group developed the Gifu hand I [14], [15], a five-fingered hand driven by built-in servomotors. We investigated the hand's potential, basing the platform of the study on dexterous grasping and manipulation of objects. Because it had a nonnegligible backlash in the gear transmission, we redesigned the anthropomorphic robot hand based on the finite element analysis to reduce the backlash and enhance the output torque. We call this version the Gifu hand II.

A 64 Point Fourier Transform Chip

Fourth generation wireless and mobile system are currently the focus of research and development. Broadband wireless system based on orthogonal frequency division multiplexing will allow packet based high data rate communication suitable for video transmission and mobile internet application. Considering this fact we proposed a data path architecture using dedicated hardwire for the baseband processor. The most computationally intensive part of such a high data rate system are the 64-point inverse FFT in the transmit direction and the viterbi decoder in the receiver direction. Accordingly an appropriate design methodology for constructing them has to be chosen a) how much silicon area is needed b) how easily the particular architecture can be made flat for implementation in VLSI c) in actual implementation how many wire crossings and how many long wires carrying signals to remote parts of the design are necessary d) how small the power consumption can be .This paper describes a novel 64-point FFT/IFFT processor which has been developed as part of a large research project to develop a single chip wireless modem.

ALGORITHM FORMULATION

The discrete fourier transformation A(r) of a complex data sequence B(k) of length N
where r, k ={0,1……, N-1} can be described as

Where WN = e-2?j/N . Let us consider that N=MT , ? = s+ Tt and k=l+Mm,where s,l ? {0,1…..7} and m, t ? {0,1,….T-1}. Applying these values in first equation and we get

This shows that it is possible to realize the FFT of length N by first decomposing it to one M and one T-point FFT where N = MT, and combinig them. But this results in in a two dimensional instead of one dimensional structure of FFT. We can formulate 64-point by considering M =T = 8

This shows that it is possible to express the 64-point FFT in terms of a two dimensional structure of 8-point FFTs plus 64 complex inter-dimensional constant multiplications. At first, appropriate data samples undergo an 8-point FFT computation. However, the number of non-trivial multiplications required for each set of 8-point FFT gets multiplied with 1. Eight such computations are needed to generate a full set of 64 intermediate data, which once again undergo a second 8-point FFT operation . Like first 8-point FFT for second 8-point again such computions are required. Proper reshuffling of the data coming out from the second 8-point FFT generates the final output of the 64-point FFT .

Fig. Signal flow graph of an 8-point DIT FFT.

For realization of 8-point FFT using the conventional DIT does not need to use any multiplication operation.

The constants to be multiplied for the first two columns of the 8-point FFT structure are either 1 or j . In the third column, the multiplications of the constants are actually addition/subtraction operation followed multiplication of 1/?2 which can be easily realized by using only a hardwired shift-and-add operation. Thus an 8-point FFT can be carried out without using any true digital multiplier and thus provide a way to realize a low- power 64-point FFT at reduced hardware cost. Since a basic 8-point FFT does not need a true multiplier. On the other hand, the number of non-trivial complex multiplications for the conventional 64-point radix-2 DIT FFT is 66. Thus the present approach results in a reduction of about 26% for complex multiplication compared to that required in the conventional radix-2 64-point FFT. This reduction of arithmetic complexity furthur enhances the scope for realizing a low-power 64-point FFT processor. However, the arithmetic complexity of the proposed scheme is almost the same to that of radix-4 FFT algorithm since the radix-4 64-point FFT algorithm needs 52 non-trivial complex multiplications.

BIT for Intelligent system design

The principal of Built-in-test and self-test has been widely applied to the design and testing of complex, mixed-signal electronic systems, such as integrated circuits (IC s) and multifractional instrumentation [1]. A system with BIT is characterized by its ability to identify its operation condition by itself, through the testing and diagnosis capabilities built into its in structure. To ensure reliable performance, testability needs to be incorporated into the early stage of system and product design. Various techniques have been developed over the past decades to implement the BIT technique. In the semiconductor, the objective of applying BIT is to improve the yield of chip fabrication, enable robust and efficient chip testing and better scope with the increasing circuit complexity and integration density. This has been achieved by having an IC chip generate its own test stimuli and measure the corresponding responses from the various elements within the chip to determine its condition. In recent years, BIT has seen increasing applications in other branches of industry, eg. manufacturing, aerospace and transportation and for the purposes of system condition monitoring. In manufacturing systems, BIT facilitates automatic detection of toolwear and breakage and assists in corrective actions to ensure part quality and reduce machine downtime.

2. BIT TECHNIQUES
BIT techniques are classified:
a. on-line BIT
b. off-line BIT
On-line BIT:
It includes concurrent and nonconcurrent techniques. Testing occurs during normal functional operation.
Concurrent on-line BIST - Testing occurs simultaneously with normal operation mode, usually coding techniques or duplication and comparison are used. [3]
Nonconcurrent on-line BIST - testing is carried out while a system is in an idle state, often by executing diagnostic software or firmware routines
Off-line BIT:
System is not in its normal working mode it usually uses onchip test generators and output response analysers or micro diagnostic routines. Functional off-line BIT is based on a functional description of the Component Under Test (CUT) and uses functional high-level fault models.
Structural off-line BIT is based on the structure of the CUT and uses structural fault models.

3. BIT FOR THE IC INDUSTRY
IC s entering the market today is more complex in design with a higher integration density. This leads to increased vulnerability of the chip to problems such as cross talk noise contamination, and internal power dissipation. These problems reduce the reliability of the chip. Further more, with increased chip density, it becomes mo0re difficult to access test points on a chip for external testing. Also, testing procedures currently in use are time consuming, presenting a bottleneck for higher productivity [2]. These factors have led to the emergence of BIT in the semiconductor industry as a cost effective, reliable, and efficient quality control technique. Generally, adding testing circuitry on to the same IC chip increases the chip area requirement conflicting with the need for system miniaturization and power conception reduction. On the other hand, techniques have been developed to allow the circuit-under-test (CUT) to be tested using existing on-chip hardware, thus keeping the area overhead to a minimum [1]. Also, the built-in-test functions obviate the need for expensive external testers. Further more; since the chip testing procedure is generated and performed on the chip itself, it takes less time as compared to one external testing procedure.

, with increased chip density, it becomes mo0re difficult to access test points on a chip for external testing. Also, testing procedures currently in use are time consuming, presenting a bottleneck for higher productivity [2]. These factors have led to the emergence of BIT in the semiconductor industry as a cost effective, reliable, and efficient quality control technique. Generally, adding testing circuitry on to the same IC chip increases the chip area requirement conflicting with the need for system miniaturization and power conception reduction. On the other hand, techniques have been developed to allow the circuit-under-test (CUT) to be tested using existing on-chip hardware, thus keeping the area overhead to a minimum [1]. Also, the built-in-test functions obviate the need for expensive external testers. Further more; since the chip testing procedure is generated and performed on the chip itself, it takes less time as compared to one external testing procedure.