Earticle

Clustering is one of the main techniques that are used to increase the scalability of MANETs, but without any security considerations clustering is prone to various security attacks. Some cryptographic-based schemes have been proposed to secure the clustering process, but they are unable to handle the internal attacks. Trust-based clustering schemes have combined the trust management systems with the existing state of art clustering solutions and using cryptographic mechanism these schemes present the most complex and secure clustering solutions that are resilient against both internal and external attackers. In this paper, we present an in-depth analysis of trust-based clustering schemes and illustrate how reputations are integrated in these schemes. Then we compare them based on the various trust metrics and finally conclude with open research issues.

The rapid proliferation of mobile computing technology has massive potential for providing access to different services at any time and from anywhere. The mobile telephone is more than just making calls. It allows accessing several applications and services via the internet connection or by building stand-alone applications. The mobile telephone has a considerable effect in tourism by allowing the user to access the contents from Internet or from an install application over the mobile devices. The existing tourist guide applications use the latest technologies to enhance the application quality by satisfying the user’s requirements. These applications encounter great challenges because of limited mobile resources. Several development platforms for mobile applications are used to design tourist guide applications a caused to mobile devices incompatibility. Some of these applications are designed using, for example, J2ME which represents an effective language for small and portable devices. But, the ideal platform, now, for this type of applications is Android, it is designed to improve efficiency and reduce resource consumption compared to J2ME. The most used technology is Java programming languages but Android is more powerful, flexible and Android phones have more functionality than J2ME phones. In this paper, we build electronic tourist guide systems using the two technologies to confirm the powerful of Android. For this reason, a comparison between the two systems is made. The applications are tailored to user preferences, so that the user can access the application from a simple interface or automatically; the information may be displayed according to GPS positioning system. The system is built to be a tourist guide for Jordan, but it is flexible and easy to be for any country. To do that, the administrator need to know the GPS coordinates of each point of interest, and then the desired information may be added to database.

This paper addresses the method of multiple cracks detection in moving parts or beams by monitoring the natural frequency and prediction of crack location and depth using Artificial Neural Networks (ANN). Determination of crack properties like depth and location is vital in the fault diagnosis of rotating machine equipments. For the theoretical analysis, Finite Element Method (FEM) is used wherein the natural frequency of beam is calculated whereas the experimentation is performed using Fast Fourier Transform (FFT) analyzer. In experimentation, simply supported beam with single crack and cantilever beam with two cracks are considered. The experimental results are validated with the results of FEM (ANSYSTM) software. This formulation can be extended for various boundary conditions as well as varying cross sectional areas. The database obtained by FEM is used for prediction of crack location and depth using Artificial Neural Network (ANN). To investigate the validity of the proposed method, some predictions by ANN are compared with the results given by FEM. It is found that the method is capable of predicting the crack location and depth for single as well as two cracks. This work may be useful for improving online conditioning and monitoring of machine components and integrity assessment of the structures.

Delay Tolerant Network (DTN) aims to provide communication between distant nodes in spite of high end to end delay and frequent disruptions in connectivity. For successful communication between a pair of nodes, a routing protocol is used. The performance of routing protocols for DTN depends upon various factors i.e. bandwidth, residual battery power processing capability and mobility of nodes. Out of these the most prominent factor is mobility. To show the impact of mobility of nodes in simulation various mobility models are used. This paper is an effort to evaluate the performance of routing protocol for DTN using Random Walk (RW) mobility model. Moreover to provide a realistic touch to the simulation environment, cyclic motion among k% of total nodes has been introduced. To carry out the above process, a simulator was designed in MATLAB-7.0. The results show that as the percentage of cyclic nodes increases, the performance of routing protocols decreases significantly.

The combined effect of EGR and cetane improver can effectively reduce the Nitrogen Oxides (NOx) emissions by reducing the combustion temperatures, since NOx formation is a temperature dependent phenomenon in diesel engines. In the present work, experimental investigations were carried out on a single cylinder four stroke naturally aspirated direct injection air cooled diesel engine with exhaust gas recirculation and cetane improver Di Tertiary Butyl Peroxide (DTBP) as an additive to diesel-biodiesel blends. The combined effect of EGR and DTBP on Brake Thermal Efficiency(BTE), Brake Specific Fuel Consumption (BSFC), cylinder pressure and exhaust emissions is studied. From experimental results it is found that an EGR percentage of around 15% results in maximum BTE and minimum BSFC. It is also found that the combined effect of EGR and cetane improver reduces the NOx emissions by 25% with a slight increase in Carbon Monoxide (CO), Hydro Carbon (HC) and smoke opacity.

To improve the drivability and reduce fuel consumption and emissions of an existing sport utility vehicle (SUV), simulation-based vehicle refinement was conducted in this study. A simulation model of the SUV was first established and validated. Both simulation and test results confirm that due to low reserve power both at low and high speed bands, the drivability, fuel economy and emissions of the SUV are unsatisfactory. To refine the vehicle, complex precautions were implemented to upgrade the diesel engine, and the powertrain gear ratios were optimized with a design of experiments (DOE) approach to match the upgraded engine. Updated simulation results demonstrate that the refined vehicle is powerful enough at a sufficient speed range, with moderate fuel consumption at Euro Ⅲ standard emissions. An interim vehicle prototype, with an upgraded engine but an unmatched transmission, was produced; field test results of the interim vehicle proved the effectiveness of the simulation-based SUV refinement. The final, fully refined SUV product is currently in development.

Noise power spectral density (PSD) estimation is a crucial part of speech enhancement system due to its contributory effect on the quality of the noise reduced speech. A novel estimation method for color noise PSD on the basis of an assumption of generalized Gamma distribution and maximum a posteriori (MAP) criterion is proposed. In the experiment, generalized Gamma PDF which is a natural extension of the Gaussian modeling of a non-white components distribution is found best fitting in four types of color noises compared with Laplace, Rayleigh distributions. After that MAP noise estimators based on the reported generalized Gamma PDF models are competed with Minimum Statistics (MS), minimum mean square error (MMSE) based PSD estimation and Maximum Likelihood estimation (MLE) noise tracking methods in evaluations. The performance of the proposed noise estimations are good as demonstrated by log error, segmental SNR and PESQ measures when they are integrated with the speech enhancement technique.

This paper provides technical support guidelines that address problems related to nail clipper progressive die for Three Seven Inc., also known as “777” in the global beauty supply market. The company’s nail clippers have not been recognized as the best of their kind because the cross sectional areas on the sides of these multipurpose nail clippers that are more recognized in the global market than in Korea are not even and have a large fracture angle and rough surface. Although 24-hour barrel work is relied upon after heat treating a nail clipper product that is produced from die to achieve even cross section, technical support for die is still needed. In this regard, clearance is revised, structure of blanking stage is changed, and strip layout drawing is modified. High-temperature tempering is conducted when constructing die in order to eliminate corrupted layers and residual stress. The results of this technical support for die through the aid of the heat treatment technical support business unit of Kongju National University showed 2.5 times and 1.3 times improvement in die repair/maintenance cycle and die life span, respectively, with a 20% increase for both quantity produced and sales. In addition, the defect rate has significantly decreased from 5% to 0.1%.

Energy is an inescapable part of today’s society and economy. Accomplishment of every work depends on the sufficient and incessant supply of energy. But the conventional fossil energy sources like oil are ultimately limited. Moreover, the increasing demand and flinching supply of oil has made the sustainable energy supply more vulnerable. So this vulnerability of conventional source of energy conducts the thinkers to think about reliable sources of fuel like fuel cell and renewable energy. It can forestall the minus impacts of global climate change, the growing risk of supply interruptions, price fluctuations and air pollution that are associated with today’s energy systems. Bring in the hydrogen economy by hydrogen and fuel cell in the minor level like household activities can be a promising solution of energy crisis in a quite unique way which also can ensure our concerns over energy supply security and climate change.

This study was conducted to identify challenges of application information and communication technology (ICTs) in Technical and Vocational Training. Using the factor analysis, the challenges have been classified into eight factors (Technical, economical, services, support, educational, cultural, legal, and educational planning) from students’ perception and five factors (legal, technical, educational, economical, and cultural) from instructors’ perception. Several suggestions have been made based upon these findings.

Steganography is going to gain its importance due to the exponential growth and secret communication of potential computer users over the internet. It can also be defined as the study of invisible communication that usually deals with the ways of hiding the existence of the communicated message. Generally data embedding is achieved in communication, image, text, voice or multimedia content for copyright, military communication, authentication and many other purposes. In image Steganography, secret communication is achieved to embed a message into cover image (used as the carrier to embed message into) and generate a stego-image (generated image which is carrying a hidden message). In this paper we have critically analyzed various steganographic techniques and also have covered steganography overview its major types, classification, applications.