Archives-June... 

Security threats for the network services have been constantly increasing day by day. Distributed denial of service (DDoS) attack is one such kind of security threat which involves multiple systems generating a large amount of traffic towards a target machine and thereby making any service from that target machine or server unavailable to its clients. This threat by nature needs no control over the target system. Traditional methods of detecting DDoS attacks are mostly centralized in nature and highly disadvantageous. To overcome the disadvantages of those schemes, we propose a distributed methodology which involves installing the attack detectors at various parts of the network. Each router in the network will monitor the traffic flowing through it and if any anomaly in the traffic pattern is detected, it will raise an alarm to the nearby routers. The alarm propagates to all the routers through which the attack flows. By this way a tree like construct is made, which will have information about number of alarms raised and the path of the attack flow. If the construct shows any converging pattern then it is declared as DDoS attack.

 Colonialism has been conceived as a policy and practice of a strong power extending its control territorially over a weaker nation or people. So, a colonial territory is that political entity over which a stronger power exercises political control. From around the mid 19th to about the mid 20th century, what we know today as the Nigerian nation-state was a classical colonial territory. Without bothering to obtain their consent or allow indigenous centripetal leaders emerge, a stronger British power proceeded not only to extend its control over the territorial space, but railroad its diverse peoples and cultures into a commonwealth they neither understood nor bargained for. What followed was a struggle of one group against the other, or others, either to ingratiate itself with the colonizing power, or assert itself against its pretensions. When the later disposition failed or became forlorn, all groups settled more or less for the former. In the midst of this novel social setting, the various cultural norms of transparency and sublime modesty in public affairs began to give way for new social ethos of competition and graft. The emerging urban areas provided a perfect arena not only for the social contact of the various culture groups, but one that saw to the flowering of seeds of dichotomy and discrimination amongst the people. This paper seeks to situate the so-called “culture of corruption” in Nigeria within the colonial environment, and posits that the aphorism, ‘culture of corruption’ is actually alien to indigenous Nigerian peoples. It contends that if the current so-called ‘War against Corruption’ must be successfully pursued, then the sublime virtues of indigenous cultures need to be propagated and adopted as national ethos. Key words: Colonialism, Corruption, Nigeria, Indigenous Culture, National Ethos.

In this paper, we have studied the photoluminescence spectroscopy of several HEMTs AlGaN/GaN high electron mobility transistors produced by molecular beam epitaxy growth. The heteroepitaxy of the nitrides of elements III is made on substrates of different nature: Silicon, Si [111]), Sapphire Al2O3 and Free-standing GaN. We thus observed constraints during growth, related to the disagreements of the mesh parameters. The EA activation energy of the free exciton A, measured by photoluminescence, varies linearly with the biaxial strain ?xx, obtained by X-ray diffraction. In addition we noticed that an evolution of the aluminum assay of 0.5% from one sample to another 5% reveals a shoulder that evolves respectively to a plateau, reproducible at different levels of excitation. This is how we interpret this phenomenon as a manifestation of 2D gas on the photoluminescence spectrum

Teachers are the back bone of society. Public and private schools are directly related with student achievements. A good school uses different strategies for student achievement. If the teachers are competent and teach students in better way, then they can achieve their goals in every field of life. This paper attempts to study the comparison of students’ achievement between public and private schools. This study shows that students’ achievement is based on quality education. Some factors affect the students achievement such as parent background, involvement of parents, low income, environment of a school and physical facilities.In this way this study shows that what influence the academic difference of public and private schools on students achievement. This study will be descriptive in nature therefore descriptive survey method of research will be used. The population of this study will comprise of all the secondary school students of distric Vehari. The sample of twenty secondary (private & public) schools will be selected from tehsil Vehari. Out of 1000 students 280 will be selected by using simple random technique. Questionnaire will be used to collect data from respondents. The collected data will be analyzed statistically by using (SPSS) software.

Separation of ions is a major problem in chemical industries. There are several techniques to separate ions, one of the technique is the use of electrokinetic valve. Electrokinetic valve is used to separate ions by applying external electric field. Earlier it is designed using CAD software. In this paper we present an approach of designing electrokinetic valve using COMSOL multiphysics in a miniature way.

Cronkhite Canada Syndrome (CCS) is a rare, non-hereditary disease that combines chronic diarrhea, diffuse intestinal polyposis and onychodystrophy. We are reporting on the observation of the first case of Cronkhite Canada Syndrome in Morocco. The case has to do with a 33-year-old patient with chronic bloody diarrhea associated with alopecia and onychodystrophy within a context of general deterioration and significant weight loss. The biological assessments were characterized by the presence of microcytic anemia with hypo albuminemia, malabsorption syndrome and hydro electrolyte disorders. The colonoscopy had shown several hamartomatous polyps located at the recto sigmoid level. The histopathological examination showed hyperplastic inflammatory polyps with extensive propria oedematous lamina, and cystic glands. The diagnosis of CCS was made in the face of a host of clinical, biological, endoscopic and histological arguments. Our patient received oral corticosteroids as treatment, along with nutritional support and a treatment of electrolyte disorders. Cronkhite Canada syndrome is associated with high mortality and a risk of malignant transformation. Clinicians should considerand think about CCS for a patient with unexplained chronic diarrhea and dermatological manifestations (Alopecia, Onychodystrophy, Hyperpigmentation).

Wavelet transforms enable us to represent signals with a high degree of scarcity. Wavelet thresholding is a signal estimation technique that exploits the capabilities of wavelet transform for signal denoising. The aim of this paper is to study various thresholding techniques such as Sure Shrink, Visu Shrink and Bayes Shrink and determine the best one for image denoising. This paper presents an overview of various threshold methods for image denoising. Wavelet transform based denoising techniques are of greater interest because of their performance over Fourier and other spatial domain techniques. Selection of optimal threshold is crucial since threshold value governs the performance of denoising algorithms. Hence it is required to tune the threshold parameter for better PSNR values. In this paper, we present various wavelet based shrinkage methods for optimal threshold selection for noise removal.

Heat exchanger is a necessary laboratory equipment in a thermo-fluid laboratory, and lack of this equipment makes learning ineffective. Hence, this study aims to design and construct a shell and tube heat exchanger for laboratory use. To achieve this aim, mechanical and thermal factors were considered. The thermal design was done using the Bell Delaware method. The heat exchanger was designed based on the assumption that there is no phase change, while water at a cold inlet temperature of 15 °C enters the heat exchanger through the tube and hot water at 100 °C enters the heat exchanger through the shell. Results show that the geometry of the heat exchanger favours turbulent flow which enhances heat transfer. This causes a heat load of 107.973 kW to be transferred from the hot fluid to the cold fluid through the tube wall when hot fluid of 0.5 kg/sec flows at a velocity of 0.3 m/s and cold fluid of 2.58 kg/sec flows with a velocity of 1 m/sec. This heat transfer caused the cold fluid temperature to increase by 10 °C as it exits the tube, while the temperature of the hot fluid fell to 45 °C as it exits the shell. The pressure drops in both the shell and tubes were within the allowable range, and hence, accepted. With the overall heat coefficient at 134.23 W/m2K and the efficiency of the system at 73.3%, the study is said to have achieved its objective.

Urban sprawl, the changed lifestyle and urbanization requires landscaping as an essential factor. Urban landscape is so important that it is currently considered as an indicator of development. Unresponsive urban parks to meet the needs of most citizens and lack of facilities and services leads to elimination of deficiencies in an urban park, often referred to as design improvement. Due to its significance as well as the lack of relevant studies, design development should be given more attention. The purpose of this study was to evaluate Shahrekord Mellat Park qualitatively and quantitatively by a documentary-analytic survey. Majority of data was collected by questionnaires distributed among users of the park. Finally, data was analysed. The findings suggest that factors such as lack of facilities and furniture, lack of vegetation, lack of social security and mismanagement of the park reduce the willingness of citizens to use these areas. Finally, suggestions were made for design improvement of Shahrekord Mellat Park.

The use of fibrous material is effective in increasing the surface area of the support media in fixed film reactors. Several fibrous biomass support mediums are available for use in attached growth system .one of these support materials are areca fibers. In this study the experiment was conducted for a batch mode of operation. The bio-reactors were continuously aerated and fed with residential wastewater having an initial average COD of 860 mg/L, BOD of 450 mg/L and NH3-N of 70 mg/L. This present study reveals the study of COD, BOD and NH3-N removal in two reactors, one filled with gravel bed and other areca fibers. Two sets of experiments were conducted to study the effects of detention time, elevated NH3-N concentration. The reactors with gravel bed and areca fibers showed reasonable amount of COD removal (72-74%), BOD removal (92%-94%) and NH3-N removal (58%-60%) within 4-16 hrs of detention period. In both the reactors denitrification was almost absent. Here comparative study of both reactors has been done and it is hypothecated that at fixed MLSS concentration of 2210 mg/L, efficiency of areca fibers bio-reactor seems to be satisfactory and effective for batch mode of operation.