Flow Sensitive Information Flow Analysis for C Programs

VITC compiler aims to provide information security to legac y C applications, using type based information flow analysis. We have re- cently modified its typing discipline to flow sensitive, whil e those of the other realistic information secure compiler implementations for Java[5]and ML[8] are flow insensitive. This is because local states in C are toofrequently stored in global variables such as errno
http://repository.vnu.edu.vn/handle/VNU_123/14454

Degradation of diferent types of polyethylene using for lining system exposed to hydro chloride acid solution

This paper focuses on degradation behavior of a maleic anhydride modified and another new modified polyethylene used for lining system as anti-corrosion agent when exposed to hydrochloric acid solution environment. Different concentrations of HCl solution ： 0, 10, and 20 mass％at temperatures of 40, 60, and 80°C were set to investigate the degradation behavior of the two types of modified polyethylene. Virgin PE was also subjected to the same conditions for comparison. Weight change, chloride element penetration, and changes in chemical structure were measured. The immersion test result showed that the diffusion of water and the HCl solution into the neat PE obeyed Fickian diffusion model while those into both modified PE obeyed Fickian mode at low temperatures only. Two-saturation stages were observed for the samples immersed in HCl solutions at 80°C . The modified PE samples were degraded bythe HCl solutions while there was no change of chemical structure for the case of the PE resin. The high temperatureenhanced the order of degradation. IR spectra showed structural changes, which maybe attributed to the modifiercomponents in the polymers.
http://repository.vnu.edu.vn/handle/VNU_123/14461

Diffusion behaviour of corrosive solution environments in carbon black filled modified polyethylene linings

The diffusion behaviour of water and HCl solution at different temperatures and concentrations into a modified polyethylene filled with carbon black used for lining is presented. It has shown the predominant role of nature of environment and carbon black content. In the both environments, an increase of environmental temperature increased the capacity of environmental absorption and the diffusion rate. The lower sorption capacity was observed at 40 and 60 o C while a higher at 80o C in the water. The two-stage diffusion appeared for the case of the corrosive environment at 80o C. An increase of carbon black loading was increased both diffusion rate and saturation values. Diffusion of the environment into the polymer proposed by the following: environmental molecules diffusing into the polymer matrix through porous system, were trapped by functional groups on the carbon black surface and polymer molecule chain, and are immobilized. This explains the increase of sorption capacity when increase carbon black loading.
http://repository.vnu.edu.vn/handle/VNU_123/14462

HANDOVER DECISION IN VISIBLE LIGHT COMMUNICATIONS

VLC is a promising communication technology in which visible light sources such as white Light Emitting Diode (LED) can be utilized as a signal transmitter, the transmission medium is spatial environment, and the appropriate photodiode can be used as a signal receiving component. Despite of many potentially advantages such as: low cost, high speed, power efficient, green communication as well as secure data communication, VLC must deal with the difficulty of distributing LEDs for smooth handover in mobility scenarios and maximize both illumination and communication aspects. In this thesis, we recommend a method to calculate the overlapped area required for smooth handover by sum of the area to make initiation handover occurs and additional area to handover successfully. This thesis is also an efficient configuration method that based on calculated overlapped areas combined with some system constraints such as: sufficient room illumination level, Field of View angle and communication aspects, those are, High Signal to Noise Ratio (SNR), high received power. By transmitting data at different frequencies for each LED lamp, this configuration method can choose the best LED lamp layout setting that gives best performance at both SNR and received power corresponding to that given parameters of room dimension and mobile terminal.
http://repository.vnu.edu.vn/handle/VNU_123/14464

Applying CBR to estimate software costs

Most of current software costs estimation approaches based on statistical models appear to be too complicated and hard to apply in reality. This paper proposes an approach to estimate software costs using Case-Based Reasoning (CBR) where the costs of a new project are estimated by firstly retrieving the similar previous project and then adapting its costs to the current conditions. The project is described as an ontology which allows the managers to estimate with various level of requirement analysis. Moreover, the statistical analysis results of the COCOMO model are utilized to reflect the domain knowledge
http://repository.vnu.edu.vn/handle/VNU_123/14500