Malicious Code and Spam in Wired and Wireless Environments: Problems and Solutions

Over the last several years digital pests - namely viruses and spam - have reached epidemic proportions, severely impacting the usability of digital communication systems, primarily affecting email. These pests result in increased bandwidth usage, increased operating costs, potential security threats and above all decreased usability. They also have the potential to create Denial of Service attacks, crippling the networks that they infect or target. Whilst to date they have been mostly confined to email, it is becoming apparent that they have the potential to impact digital communications infrastructure of the future. For example, concerns have already been raised with regards to the potential impact of spam on Voice over IP. Spam and viruses have also been appearing within other technologies and communication media, including mobile phone networks and hand held devices. To combat the above mentioned security problems, we propose an email scanning gateway using open source tools, whilst ensuring that the gateway can be readily deployed in a commercial environment. In this paper we present details of the design and implementation, and discuss several possible applications of our proposed syste

A new architecture for dynamic e-business database interoperability

There have been many approaches of data sharing in e-businesses, attempting at mapping each field at the source to its corresponding field at the target. These approaches eliminate the need for deriving the global schema and hence eliminate a substantial overhead. But, the approaches work out well only when both the source and the target databases have approximately the same content. Moreover, if some concepts of source do not have the counterpart fields in the target then the mapping will lose the concepts. This problem will be further aggregated by the mapping compositions and the large size of the databases. In this paper, we propose a framework to alleviate the interoperability problem

Maintaining the integrity of XML signatures by using the manifest element

One of the aims of providing 'security of data' in e-commerce transactions is making sure that the receiver receives the same data which the sender sends, that is the data has not been tampered in any way. To achieve this aim digital signatures are used. A digital signature helps in providing integrity, message authentication, and signer authentication for the signed data. An XML signature can contain or point to the data that is being signed. In this paper we discuss a possible solution of avoiding a signature from breaking when there is a change in the location of the document after it has been signed

Self-gravitating spheres of anisotropic fluid in geodesic flow

The fluid models mentioned in the title are classified. All characteristics of the fluid are expressed through a master potential, satisfying an ordinary second order differential equation. Different constraints are imposed on this core of relations, finding new solutions and deriving the classical results for perfect fluids and dust as particular cases. Many uncharged and charged anisotropic solutions, all conformally flat and some uniform density solutions are found. A number of solutions with linear equation among the two pressures are derived, including the case of vanishing tangential pressure.Comment: 21 page

Numerical analyses for improved terminal velocity of deep water torpedo anchor

Purpose: This research aims to investigate the effects of manipulation of a torpedo’s geometries to attain higher terminal velocity. The parameters of interest include geometric changes of the original design, as well as sea water properties that reflect water depth in South China Sea. Design/methodology/approach: The research make use of computational fluid dynamics (CFD) software, FLUENT, to solve viscous incompressible Navier–Stokes equations with two equations k-epsilon turbulent model. The calculated drag coefficient is subsequently used to calculate the maximum attainable terminal velocity of the torpedo. Findings: It was found that the terminal velocity can be improved by sharper tip angle, greater aspect ratio, greater diameter ratio and optimum rear angle at 30°. Sensitivity of drag coefficient toward each of the parameters is established in this paper. Originality/value: The paper, in addition to verifying the importance of aspect ratio, has also established the tip angle, diameter ratio and rear angle of the torpedo as important geometric aspects that could be tuned to improve its terminal velocity