Archives-May 2013

Wireless ad-hoc networks allow the construction of flexible and adaptive networks with no fixed infrastructure or any base station. The core challenge is to develop efficient routing protocols for the dynamic nodes to commune with each other without any hazard or latency. A number of routing protocols such as Dynamic Source Routing (DSR), Ad Hoc on Demand Distance Vector Routing (AODV), Destination–Sequenced Distance Vector (DSDV) and Temporally Ordered Routing Algorithm (TORA) have already been presented for the communication purpose while AODV outperforms the others in terms of the efficiency. Considering several performance factors such as the packet delivery fraction (PDF), end to end delivery, normalized routing overload and the normalized MAC, this paper has proposed an improvement over the existing AODV protocol and termed it as I-AODV (improved AODV). Effectiveness of the proposed I-AODV algorithm under different level of nodal mobility is confirmed through Cygwin simulation.

Low temperature offers an exciting opportunity to understand physical properties of various material and process. Electrical contact resistance which is fairly understood at room temperature behaves in entirely difference way at temperatures below the room temperature. Estimation of contact resistance and its behavior at low temperatures is not only necessary for its application areas but for understanding the contact mechanism and controlling the contact resistance. Low temperature experiments are highly time-consuming, due to the inherent thermal design of these systems, which takes a lot of time to stabilize. Automation of these experiments not only eases the experimentation but also improve the result accuracy.

We explore an alternate approach to the origin of primordial fluctuations using extra dimensions. A non-inflationary cosmology is considered, with the evolution of 4 + d dimensions from the initial singularity. The extra dimensions evolve more rapidly than the ordinary space and reach their maximum volume in a short interval of time, at the end of which they get stabilized. Due to random interactions between the bulk and the brane, the entropy may be sucked from the normal space. These interactions occur only for a short interval of time and hence only a small amount of entropy is consumed. An approximate equation which describes the decrease in entropy, in a region of normal space, is constructed. Finally, this violation of law of entropy is related to the increase in density of that region of space by simple thermodynamic considerations. This process occurs randomly in different regions of normal space generating the primordial fluctuations in density, which grow over time and eventually become the universe we see today.

Recognizing faces is something that people usually do effortlessly and without much conscious thought, yet it has remained a difficult problem in the area of computer vision, where some 20 years of research is just beginning to yield useful technological solutions. As a biometric technology, automated face recognition has a number of desirable properties that are driving research into practical techniques. The problem of face recognition can be stated as ‘identifying an individual from images of the face’ and encompasses a number of variations other than the most familiar Application of mug shot identification. One notable aspect of face recognition is the broad interdisciplinary nature of the interest in it: within computer recognition and pattern recognition; biometrics and security; multimedia processing; psychology and neuroscience. It is a field of research notable for the necessity and the richness of interaction between computer scientists and psychologists. The automatic recognition of human faces spans a variety of different technologies. At a highest level, the technologies are best distinguished by the input medium that is used, whether visible light, infra-red or 3-dimensional data from stereo or other range-finding technologies. Thus far, the field has concentrated on still, visible-light, photographic images, often black and white, though much interest is now beginning to be shown in the recognition of faces in colour video. Each input medium that is used for face recognition brings robustness to certain conditions, e.g. infra-red face imaging is practically invariant to lighting conditions while 3-dimensional data in theory is invariant to head pose. Imaging in the visible light spectrum, however, will remain the preeminent domain for research and application of face recognition because of the vast quantity of legacy data and the ubiquity and cheapness of photographic capture equipment.

Cognitive radios hold tremendous promise for increasing spectral efficiency in wireless systems. The spectrum sensing problem has gained new aspects with cognitive radio and opportunistic spectrum access concepts. It is one of the most challenging issues in cognitive radio systems. A cognitive radio is an intelligent wireless communication device that exploits side information about its environment to improve spectrum utilization. Spectrum shortage was born the idea for cognitive radios. These devices utilize advanced radio and signal processing technology along with novel spectrum allocation policies to support new wireless users operating in the existing crowded spectrum, without degrading the performance of entrenched users. In this paper we present a Cognitive Radio approach for usage of Virtual Unlicensed Spectrum , a vision of a Cognitive Radio (CR) based approach that uses allocated spectrum in a opportunistic manner to create “virtual unlicensed bands” i.e. bands that are shared with the primary (often licensed) users on a non-interfering basis. Dynamic spectrum management techniques are used to adapt immediate local spectrum availability. One of the most important components of the cognitive radio concept is the ability to measure, sense, learn, and be aware of the parameters related to the radio channel characteristics, availability of spectrum and power, radio’s operating environment, user requirements and applications, available networks (infrastructures) and nodes, local policies and other operating restrictions. In cognitive radio terminology, primary users can be defined as the users who have higher priority or legacy rights on the usage of a specific part of the spectrum.

Sensor networks have been widely employed in many real-time applications. One of the most obvious challenges appearing to threaten the successful deployment of sensor networks is privacy issues including source-location privacy which can not be adequately addressed by general security mechanisms. Focusing on this important kind of privacy, among many approaches proposed in literatures, self-adjusting phantom routing is a very successful one. But it still has some weaknesses. In this paper, we propose an improved version of it to enhance its performance. This method can decrease energy consumption and communication cost while increase the accuracy of the aggregate locations by minimizing their monitored areas.

Collocation is one of the most problematic areas in second language learning and it seems that if one wants to improve his/her communication in another language the collocational competence should be improved. The purpose of this study was to examine the effect of applying Collins Collocation Dictionary as a concordancing tool on learning lexical collocations of Iranian EFL university students. After selecting 30 students randomly, they were divided into 2 groups: experimental group and control group. A pretest was taken from both groups at the same time. In the following week concordancing practice (task1) was given to the students in the experimental group and they were asked to work with10 lexical collocations and identify (mis)collocations. At the same time students in control group received some texts and they were asked to notice the lexical collocations. Then, posttest1 was given to the students in both groups. In the next week, the same procedure with 10 other lexical collocations was repeated and posttest 2 was administered. The results showed that the experimental group performed better on lexical collocations than the control group and their results were significant.

In recent time, there is increasing interest in diversified agricultural production systems to obtain higher yields per unit area through better use of natural resources, minimizing the incidence of insect pests and diseases, greater stability and crop insurance offered by intercropping systems. Field experiment was conducted during the rainy seasons of 2011 and 2012 at the Teaching and Research Farm of the Faculty of Agriculture, Nasarawa State University, Keffi – Lafia Campus to study the effect of poultry manure and planting arrangement on the soil physico-chemical properties and yield of Sesame/groundnut mixture. The experiment consisted of four rates of poultry manure (0, 3.0, 6.0 and 9.0 t ha-1) and two planting arrangement (single alternate row and double alternate row planting arrangement). The eight treatment combinations were laid out in randomized complete block design with four replications. The results obtained showed that the soil physical structure was slightly improved; total N, available P and organic carbon of the experimental soil were increased by 20, 62 and 6% respectively after the experiment. Yield and yield characters of the two crops were significantly increased by the application of 6 t ha-1 of poultry manure and double row planting arrangement. Land equivalent ratio was greater than unity indicating that the intercropping system was advantageous.

In today’s modern and digital world countless milestones have been achieved by the human. Technology has completely enveloped us in some way or the other. Hence if there is not complete dependency but most it is on the use of technology. For example, communicating with someone using a device is technology. Today, there are endless organizations that are maneuvering in recent advancements in technology. Among these the one which concerns us is to secure information or data on the network. Network security is the most functional requirement of any system. So the question arises that how to secure the data on the network from the intruder. There are innumerable intrusion detection techniques to detect the intrusion in the system. This paper deals with some handful of the techniques with which we can secure our data on the network.

The density (?), viscosity (?) and ultrasonic velocity (U) have been measured for the binary mixtures of Brompheniramine with 1-Butanol at 303,308 and 313K. From the experimental data, several acoustic parameters such as adiabatic compressibility (?), free length (L_f), free volume (V_f), viscous relaxation time (?) and Gibbs free energy (?G) have been calculated. The excess values of the above parameters (?^E, L_f^E, V_f ^E ,?^E and ?G^E ) were also determined and interpreted in terms of molecular association such as hydrogen bonding formed between the liquid mixtures. The results show that hetero association and homo association of molecules decrease with increase in the temperature.