An a posteriori error analysis of a mixed finite element Galerkin approximation to second order linear parabolic problems

In this article, a posteriori error estimates are derived for a mixed finite element Galerkin approximation to second order linear parabolic initial and boundary value problems. Using mixed elliptic reconstruction method, a posteriori error estimates in $L^\infty(L^2)$ and $L^2(L^2)$-norms with optimal order of convergence for the solution as well as its flux are proved for the semidiscrete scheme. Finally, based on backward Euler method, a completely discrete scheme is analyzed and a posteriori bounds are derived, which improves earlier results on a posteriori estimates for mixed parabolic problems

Why physicians and lay people smoke and how can it be reduced?

Objective: The objective of this study was to find out the level of knowledge the physicians and lay people have pertaining to the effect of cigarettes, why certain physicians smoke and what measures could be applied to reduce the rate of smoking. Methods: A questionnaire was administered to the one hundred physicians who smoke, one hundred non-smoking physicians and one hundred lay people who smoke to determine their attitude towards this addition. Subjects were chosen using convenience sampling. The physicians were picked from six hospitals of Karachi. Results: When the smoking physicians were asked what could motivate them to stop smoking, majority of them said that an occurrence of a smoking related illness would. Majority of the physicians who do not smoke felt that individual will was the greatest force keeping them from smoking. When asked how smoking can be reduced in Pakistan, majority of the physicians, both smoking and non-smoking, favoured mass health education. Lay smokers expressed marked ignorance about deleterious effects of cigarette smoke. Like smoking physicians, majority of them said that occurrence of an illness related to smoking would effectively motivate them to stop smoking. CONCLUSION: Based on this survey we conclude that mass health education and enforcement of the ban on smoking in public places will effectively reduce the number of smokers. There is a need to educate physicians and the general public about the cardiac and carcinogenic effects of smoking

Effect of hot-arid climatic solar energy on monocrystallinephotovoltaic performance in Pakistan

The domestic dwellings in Pakistan have predominantly implemented low-carbon strategies by harvesting solar energy using photo-voltaic (PV) panels as a long-term vision of low-carbon economy. Most of the urban areas in Pakistan stay hot and humid in an entire year. Consistent solar irradiation at higher temperatures is one of the major factors that affect the power generation performance of monocrystalline PV systems pose challenges to performance and degradation issues. Monocrystalline PV module efficiencies are declining and damaging under the continuous exposure to higher surface day-time temperatures in the different parts of the country. MATLAB simulations were performed based on the validated mathematical approach. This paper investigates the hot arid surface temperature impacts on the performance of PV modules during the summer and winter seasons in Pakistan. The investigations are performed examining the comparative output power generating performance of the PV system. This paper also investigates the influence of installations of PV-system in the North, South, East and West regions of Pakistan. It was examined that the northern areas of Pakistan are more suitable for maintaining the long-term durability of the PV system. Investigations are performed for the peak summer and peak winter days. During summer months, cooling strategies have to be implemented to overcome the heating effects whilst reducing degradation effect on installed PV-system

JPEG2000 compatible neural network based cipher

In this paper, an efficient encryption technique is proposed, especially for JPEG2000 compatible images.The technique uses a multilayer neural network to generate a pseudo-random sequence for transforming wavelet subbands into cipher subbands.The neural network generator takes 64 bit key as a startup seed with additional 64 bit key for initial weights and biases.At each layer, output is calculated by several iterations to increase the complexity of the pseudorandom sequence generation.In order to examine effectiveness of this approach, various tests including correlation, histogram, key space etc. are conducted on test images, and the results demonstrate the robustness of the proposed approach

Embedding Authentication and DistortionConcealment in Images – A Noisy Channel Perspective

In multimedia communication, compression of data is essential to improve transmission rate, and minimize storage space. At the same time, authentication of transmitted data is equally important to justify all these activities. The drawback of compression is that the compressed data are vulnerable to channel noise. In this paper, error concealment methodologies with ability of error detection and concealment are investigated for integration with image authentication in JPEG2000.The image authentication includes digital signature extraction and its diffusion as a watermark. To tackle noise, the error concealment technologies are modified to include edge information of the original image.This edge_image is transmitted along with JPEG2000 compressed image to determine corrupted coefficients and regions. The simulation results are conducted on test images for different values of bit error rate to judge confidence in noise reduction within the received images

Approximate trigonometric expansions with applications to signal decomposition and coding

Signal representation and data coding for multi-dimensional signals have recently received considerable attention due to their importance to several modern technologies. Many useful contributions have been reported that employ wavelets and transform methods. For signal representation, it is always desired that a signal be represented using minimum number of parameters. The transform efficiency and ease of its implementation are to a large extent mutually incompatible. If a stationary process is not periodic, then the coefficients of its Fourier expansion are not uncorrelated. With the exception of periodic signals the expansion of such a process as a superposition of exponentials, particularly in the study of linear systems, needs no elaboration. In this research, stationary and non-periodic signals are represented using approximate trigonometric expansions. These expansions have a user-defined parameter which can be used for making the transformation a signal decomposition tool. It is shown that fast implementation of these expansions is possible using wavelets. These approximate trigonometric expansions are applied to multidimensional signals in a constrained environment where dominant coefficients of the expansion are retained and insignificant ones are set to zero. The signal is then reconstructed using these limited set of coefficients, thus leading to compression. Sample results for representing multidimensional signals are given to illustrate the efficiency of the proposed method. It is verified that for a given number of coefficients, the proposed technique yields higher signal to noise ratio than conventional techniques employing the discrete cosine transform technique

Testing Onion Market Integration in Pakistan

This paper analyses spatial market integration using monthly wholesale real price of onion in four regional markets located in each of the four provinces of Pakistan. Unit root test indicates that the price series in each location are stationary, and the series are represented as autoregressive model for eachlocation. The error correction model results show that the regional markets of onion have strong price linkages, and thus are spatially integrated.