Characteristics and effect of thermal treatment on surface texture of ultrafine zirconia powders

Yttria-stabilized zirconia ultrafine powders were prepared by the hydrolysis of their hydroxide at 200° C. The powders obtained were investigated for their crystal structure and degree of fineness. The surface characteristics of the prepared powders were determined by nitrogen gas adsorption. The effect of calcination conditions on the powder characteristics were thoroughly investigated and the results discussed in relation to their surface textures and degree of crystallinity.     

Efficient Data Compression of ECG Signal Based on Modified Discrete Cosine Transform

This paper introduced an efficient compression technique that uses the compressive sensing (CS) method to obtain and recover sparse electrocardiography (ECG) signals. The recovery of the signal can be achieved by using sampling rates lower than the Nyquist frequency. A novel analysis was proposed in this paper. To apply CS on ECG signal, the first step is to generate a sparse signal, which can be obtained using Modified Discrete Cosine Transform (MDCT) on the given ECG signal. This transformation is a promising key for other transformations used in this search domain and can be considered as the main contribution of this paper. A small number of wavelet components can describe the ECG signal as related work to obtain a sparse ECG signal. A sensing technique for ECG signal compression, which is a novel area of research, is proposed. ECG signals are introduced randomly between any successive beats of the heart. MIT-BIH database can be represented as the experimental database in this domain of research. The MIT-BIH database consists of various ECG signals involving a patient and standard ECG signals. MATLAB can be considered as the simulation tool used in this work. The proposed method's uniqueness was inspired by the compression ratio (CR) and achieved by MDCT. The performance measurement of the recovered signal was done by calculating the percentage root mean difference (PRD), mean square error (MSE), and peak signal to noise ratio (PSNR) besides the calculation of CR. Finally, the simulation results indicated that this work is one of the most important works in ECG signal compression.     

Pressure vessel steels: influence of chemical composition on irradiation sensitivity

Neutron irradiation of steels used in the construction of nuclear reactor pressure vessels can lead to the embrittlement of these materials, i.e. increasing the ductile-to-brittle transition temperature and decreasing the fracture energy, which can limit the plant life. The knowledge of irradiation embrittlement and the means for minimizing such degradation is therefore important in the field of assuring the safety of nuclear power plants.

Irradiation embrittlement is quite a complex process. It involves many variables. The most important of these are irradiation temperature, neutron fluence (neutron dose), neutron flux (neutron dose rate) and chemical composition of the irradiated material. This paper is concerned with the effect of chemical composition, i.e. the role of residual and alloying elements in the irradiation embrittlement of nuclear reactor pressure vessel steels in light water reactors. It presents a critical review for the published work in this field over the last 25 years.     

Comparison of measured and predicted performance of heat storage unit packed with spheres of a local material

The present paper presents a comparison between the measured and predicted performance of a sensible heat storage unit. The storage unit is packed with spheres manufactured from a powder of certain type of Egyptiain clay (trade name “tafla”) produced at Abu-Siebera, Aswan. A special experimental set up was designed to predict the performance of the storage unit. The temperature distribution of the solid spheres was measured at different mass flow rates and at different time intervals. A comparison was made between these measured values and the corresponding values obtained using a numerical model based on finite difference techniques. The results showed a reasonable agreement between the measured and predicted temperature distribution. Finally, the pressure drop through the storage unit was measured and compared with the corresponding pressure drop calculated using two different empirical formulae.