Collision frequencies and electron temperatures in the lower ionosphere

Collision frequencies and electron temperatures in lower ionospher

Simple Finite Non-Abelian Flavor Groups

The recently measured unexpected neutrino mixing patterns have caused a resurgence of interest in the study of finite flavor groups with two- and three-dimensional irreducible representations. This paper details the mathematics of the two finite simple groups with such representations, the Icosahedral group A_5, a subgroup of SO(3), and PSL_2(7), a subgroup of SU(3).Comment: 42 pages, matches published version, references adde

Electroweak Phase Transition in the U(1)' MSSM

In this work, we have investigated the nature of the electroweak phase transition in the U(1) extended minimal supersymmetric standard model without introducing any exotic fields. The effective potential has been estimated exactly at finite temperature taking into account the whole particle spectrum. For reasonable values of the lightest Higgs and neutralino, we found that the electroweak phase transition could be strongly first order due to: (1) the interactions of the singlet with the doublets in the effective potential, and (2) the evolution of the wrong vacuum that delays the transition.Comment: substantial changes, references added, 18 pages, 4 figure

Perceptions of faculty and students toward the obstacles of implementing e -government in educational institutions in Saudi Arabia

The purpose of this study was to examine the perceptions of faculty members and students towards the obstacles of e-government implementation in educational institutions in Saudi Arabia. To collect data, the researcher developed two surveys and employed a quantitative research technique. The research population involved 101 faculty members and 305 students from the IPA, KSU and IMBSIU. Descriptive statistics, frequency and percentage were conducted for each variable. Means and standard deviations for all Likert-type scale variables were calculated. Testing for the equality of groups\u27 means was conducted using t-test or Analyses of Variance (ANOVA). The level of significance was 0.05 for all tests. The collected data was analyzed using the Statistical Packages for the Social Sciences (SPSS). Depending on literature, 46 statements were identified as obstacles. The results of the study show that 37 of the identified obstacles prevent or influence e-government implementation in educational institutions. The identified obstacles were then categorized into six groups: educational, organizational, political, financial, social, and technological obstacles, ranked from highest to lowest mean. There was no statistically significant difference between groups of students and faculty members, males and females, and respondents from different institutions regarding all variables. However, a t-test revealed significant difference in participants from different academic majors with respect to their total scores on responses related to financial obstacles.;The study suggests that the e-government implementation should be done gradually throughout comprehensive planning. Therefore, a comprehensive plan should be made that includes all factors and aspects organizational, educational, financial, legislative, technological, and environmental. Also, e-government implementation needs to be integrated into the national curriculums from primary school to higher education. Furthermore, it is recommended that educational institutions should offer workshops, training programs, seminars and conferences regarding e-government implementation, as well as conducting a massive campaign to raise social awareness of e-government advantages. Also, fundamental changes in organizational behavior are necessary to overcome resistance to change. Educational institutions need to establish teams in each institution to be in charge of e-government applications and also support them by adequate budget and authority. The IPA should play an active role in training governmental employees in e-government applications, offering consultations, and performing research in this regard as well

Rapid generation of angular momentum in bounded magnetized plasma

Direct numerical simulations of two-dimensional decaying MHD turbulence in bounded domains show the rapid generation of angular momentum in nonaxisymmetric geometries. It is found that magnetic fluctuations enhance this mechanism. On a larger time scale, the generation of a magnetic angular momentum, or angular field, is observed. For axisymmetric geometries, the generation of angular momentum is absent; nevertheless, a weak magnetic field can be observed. The derived evolution equations for both the angular momentum and angular field yield possible explanations for the observed behavior

Capacity of Control for Stochastic Dynamical Systems Perturbed by Mixed Fractional Brownian Motion with Delay in Control

In this paper, we discuss the relationships between capacity of control in entropy theory and intrinsic properties in control theory for a class of finite dimensional stochastic dynamical systems described by a linear stochastic differential equations driven by mixed fractional Brownian motion with delay in control. Stochastic dynamical systems can be described as an information channel between the space of control signals and the state space. We study this control to state information capacity of this channel in continuous time. We turned out that, the capacity of control depends on the time of final state in dynamical systems. By using the analysis and representation of fractional Gaussian process, the closed form of continuous optimal control law is derived. The reached optimal control law maximizes the mutual information between control signals and future state over a finite time horizon. The results obtained here are motivated by control to state information capacity for linear systems in both types deterministic and stochastic models that are widely used to understand information flows in wireless network information theory. The contribution of this paper is that we propose some new relationships between control theory and entropy theoretic properties of stochastic dynamical systems with delay in control. Finally, we present an example that serve to illustrate the relationships between capacity of control and intrinsic properties in control theory.Comment: 17 pages, 2 example

Neural network and multiple linear regression to predict school children dimensions for ergonomic school furniture design

The current study investigates the possibility of obtaining the anthropometric dimensions, critical to school furniture design, without measuring all of them. The study first selects some anthropometric dimensions that are easy to measure. Two methods are then used to check if these easy-to-measure dimensions can predict the dimensions critical to the furniture design. These methods are multiple linear regression and neural networks. Each dimension that is deemed necessary to ergonomically design school furniture is expressed as a function of some other measured anthropometric dimensions. Results show that out of the five dimensions needed for chair design, four can be related to other dimensions that can be measured while children are standing. Therefore, the method suggested here would definitely save time and effort and avoid the difficulty of dealing with students while measuring these dimensions. In

A Digital Data Acquisition System for High Subsonic Speed Wind Tunnels

The need to reduce time and cost of running high speed (transonic & supersonic) wind tunnels and to obtain reliable experimental data is very essential to the academic and industrial worlds of aviation. Data acquisitioning technology together with the advents in computer programming made the prospects of upgrading old technology wind tunnels (those manually driven and using mercury or water manometers) a reality. Simple hardware and software are available and are cheap and very effective and can be easily installed for the purposes stated. The present paper describes a data acquisition system, suggested and installed, by the author for use on the supersonic wind tunnel at the university of Hertfordshire/UK. The tunnel layout and the acquisition system are described together with some of the validation experimental runs. The experiments were carried out originally as part of the author’s PhD research work investigating the effects of aerofoil surface irregularities at high subsonic speeds using the viscous Garabedian & Korn (VGK) method [1]