Room Temperature Ferromagnetism in Ga1-xHoxN (x=0.0 and 0.05) Diluted Magnetic Semiconductor Thin Films

Holmium doped GaN diluted magnetic semiconductor thin films have been prepared by thermal evaporation technique and subsequent ammonia annealing. X-ray diffraction mea-surements reveal all peaks belong to the purely hexagonal wurtzite structure. Surface mor-phology and composition analysis were carried out by scanning electron microscopy and energy dispersive spectroscopy respectively. The room temperature ferromagnetic proper-ties of Ga_1-xHo_xN(x=0.0, 0.05) films were analyzed using vibrating sample magnetometer at room temperature. Magnetic measurements showed that the undoped films (i.e. GaN) exhibited diamagnetic behavior, while the Ho-doped (Ga_0.95Ho_0.05N) film exhibited a ferro-magnetic behavior.     

Stability of imperfect stiffened conical shells

A general procedure is developed for stability of stiffened conical shells. It is used for studying the sensitivity behavior with respect to the stiffener configurations. The effect of the pre-buckling nonlinearity on the bifurcation point, as well as the limit-point load level, is examined. The unique algorithm presented by the authors is an extended version of an earlier one, adapted for determination of the limit-point load level of imperfect conical shells. The eigenvalue problem is iteratively solved with respect to the nonlinear equilibrium state up to the bifurcation point or to the limit-point load level.A general symbolic code (using MAPLE) was programmed to create the differential operators based on Donnell’s type shell theory. Then the code uses the Galerkin procedure, the Newton–Raphson procedure, and a finite difference scheme for automatic development of an efficient FORTRAN code which is used for the parametric study.     

Discontinuous Galerkin relaxation algorithm for solute transport in porous media

We consider a degenerate parabolic convection dominated equation which models the transport of contaminant in porous media. The numerical scheme is fulfilled by combining the DG – Discontinuous Galerkin Method with and an efficient relaxation algorithm that recently developed. Numerical results show the efficiency of our scheme. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Investigation of the optimal annealing temperature for the enhanced thermoelectric properties of MOCVD-grown ZnO films

In this study, we demonstrate the optimization of the annealing temperature for enhanced thermoelectric properties of ZnO. Thin films of ZnO are grown on a sapphire substrate using the metal organic chemical Vapor Deposition (MOCVD) technique. The grown films are annealed in an oxygen environment at 600–1000°C, with a step of 100°C for one hour. Seebeck measurements at room temperature revealed that the Seebeck coefficient of the sample that was not annealed was 152 μV/K, having a carrier concentration of N _D ~ 1.46 × 10¹⁸ cm^–3. The Seebeck coefficient of the annealed films increased from 212 to 415 μV/K up to 900°C and then decreased at 1000°C. The power factor is calculated and found to have an increasing trend with the annealing temperature. This observation is explained by the theory of Johnson and Lark–Horovitz that thermoelectric properties are enhanced by improving the structure of ZnO thin films. The Hall measurements and PL data strongly justify the proposed argument.     

基于深度学习的位置大数据统计发布与隐私保护方法

针对传统位置大数据统计划分发布结构不合理、划分发布方法效率低下的问题,提出一种基于深度学习的位置大数据统计划分结构预测方法和差分隐私发布方法,以提高位置大数据统计划分发布数据的可用性和执行效率.首先对二维空间进行细致划分和自底向上合并,从而构建合理的空间划分结构.然后将划分结构矩阵组织为三维时空序列,借助深度学习模型提...     

Efficient method for designing chaotic S-boxes based on generalized Baker’s map and TDERC chaotic sequence

The theory of chaos is applied to the construction of substitution boxes used in encryption applications. The synthesis process of the proposed substitution boxes is presented, which is based on chaotic Baker’s map and TDERC chaotic sequences. The objectives of the new substitution box are to provide enhanced resistance against differential and linear cryptanalysis. The constructed substitution boxes uses Galois field elements and relies on discrete chaotic maps while keeping differential and linear approximation probabilities to desired levels.     

A novel method for designing nonlinear component for block cipher based on TD-ERCS chaotic sequence

A substitution box is used to induce nonlinearity in plaintext for encryption systems. Recently, the application of chaotic maps to encryption applications has resulted in some interesting nonlinear transformations. In this paper, we propose an efficient method to design nonlinear components for block ciphers that are based on TD-ERCS chaotic sequence. The new substitution box is analyzed for nonlinearity, bit independence, strict avalanche criterion, generalized majority logic criterion, and differential and linear approximation probabilities. The results show high resistance to differential and linear cryptanalysis in comparison to some recently proposed chaotic substitution boxes.     

Determination of macronutrients,micronutrients, non-essential elements in milk based-infant formulas by atomic absorption and inductively coupled plasma-optical emission spectroscopy after microwave and ultrasound assisted digestion

Microwave and ultrasound procedures for samples preparations were adopted and the elements were determined by validated flame atomic absorption and inductively coupled plasma–optical emission spectrometry. Student’s t-test was established whether there was a difference between the sample preparation methods. Trueness of certified values by all methods was ensured which were not differing significantly at 95% level of confidence interval. The highest intensity ratio of magnesium (II)/magnesium (I) was obtained at 1120 radiofrequency value to achieve accurate and reproducible results by inductively coupled plasma–optical emission spectrometry. The value of corresponding correlation coefficient (r²) were obtained as >0.990 indicating the excellent linearity for concentration range chosen for each element to be determined in commercial samples. Results showed that concentrations of calcium, magnesium, potassium, sodium, chromium, copper, iron, manganese, selenium, and zinc found in commercially available products are in good agreement with label as declared by the manufacturers. Exposure to aluminum, cadmium, and lead from consumption of products under evaluation was estimated and it was in compliance with permissible level suggested by European Commission regulations. Regarding the food safety monitoring, the proposed methods are rapid and met green chemistry approach so that can be implemented in laboratories easily for routine analysis.     

Association study of the angiotensin-converting enzyme (ACE) gene G2350A dimorphism with myocardial infarction

The angiotensin converting enzyme (ACE) is a strong candidate gene for myocardial infarction (MI). Insertion-deletion dimorphism in intron 16 of this gene has been inconclusively found to be associated with it. Several new polymorphisms in the ACE gene have been identified and among these, a dimorphism in exon 17, ACE G2350A, has a significant effect on plasma ACE concentrations. To assess the value of genotyping the ACE G2350A dimorphism in a genetically homogeneous population, we carried out a case-control study of dimorphism G2350A for a putative association with MI among Pakistani nationals. We investigated a sample population of 370 Pakistanis, comprising 163 controls, and 207 patients with clinical diagnosis of acute MI (AMI). ACE G2350A alleles were visualized by assays based on polymerase chain reaction and restriction endonuclease analysis. Frequencies of G alleles were 0.68 among controls and 0.72 among AMI patients. The ACE G2350A dimorphism showed no significant association with MI (chi2 = 0.90, 2 df, P = 0.64), plasma levels of homocysteine (P = 0.52) or with serum levels of folate (P = 0.299). The results indicate that ACE G2350A polymorphism is not associated with risk of myocardial infarction in the Pakistani population investigated here.     

A mechanism and kinetics of discharge pumped mercury bromide lasers

Emission spectra of the HgBr (B²Σ⁺-Z ²Σ⁺) band system and atomic mercury lines observed during collisions of HgBr₂ with N⁺/N₂⁺ ions at different laboratory kinetic energies are discussed. Emission cross sections of the most intense band of the HgBr transition at 502 nm have been measured at low energies of the projectile ions. Collision-induced dissociative excitation processes appear to be the dominant mechanism producing these emissions