Simulation of electron transport in quantum well devices

Double barrier resonant tunneling diodes (DBRTD) have received much attention as possible terahertz devices. Despite impressive experimental results, the specifics of the device physics (i.e., how the electrons propagate through the structure) are only qualitatively understood. Therefore, better transport models are warranted if this technology is to mature. In this paper, the Lattice Wigner function is used to explain the important transport issues associated with DBRTD device behavior

The dynamics and control of large flexible space structures, 3. Part A: Shape and orientation control of a platform in orbit using point actuators

The dynamics, attitude, and shape control of a large thin flexible square platform in orbit are studied. Attitude and shape control are assumed to result from actuators placed perpendicular to the main surface and one edge and their effect on the rigid body and elastic modes is modelled to first order. The equations of motion are linearized about three different nominal orientations: (1) the platform following the local vertical with its major surface perpendicular to the orbital plane; (2) the platform following the local horizontal with its major surface normal to the local vertical; and (3) the platform following the local vertical with its major surface perpendicular to the orbit normal. The stability of the uncontrolled system is investigated analytically. Once controllability is established for a set of actuator locations, control law development is based on decoupling, pole placement, and linear optimal control theory. Frequencies and elastic modal shape functions are obtained using a finite element computer algorithm, two different approximate analytical methods, and the results of the three methods compared

A Comparative Study of Text Summarization Based on Synchronous and Asynchronous PSO

Text summarization is the process of extracting the most important sentences from the original document without its meaning change. The paper focus on Extractive summarization technique which chooses the important sentences from the document and integrates into summary. An extractive summarization technique, Particle swarm Optimization performs arithmetic operations that enhances a problem, by iteratively trying to improve possible solution with regard to input data. It determines a problem by having a population of possible solutions moving around the search space according to arithmetic formulae over the particles position and velocity. The sequence of modernized particles of PSO can be categorized into Synchronous PSO (S-PSO) and Asynchronous PSO(A-PSO). In synchronous PSO, after calculating the whole performance, velocities and positions of the particles are modernized, this increases the performance. In A-PSO after calculating its performance, velocities and positions of the particles are modernized using partial data which leads to extreme analysis. The comparative study on the synchronous PSO and asynchronous PSO with the precision and recall values for different datasets is considered. Asynchronous PSO has higher precision and recall values compared to synchronous PSO. Asynchronous PSO leads to extreme analysis of data

The dynamics and control of large flexible space structures-IV

The effects of solar radiation pressure as the main environmental disturbance torque were incorporated into the model of the rigid orbiting shallow shell and computer simulation results indicate that within the linear range the rigid modal amplitudes are excited in proportion to the area to mass ratio. The effect of higher order terms in the gravity-gradient torque expressions previously neglected was evaluated and found to be negligible for the size structures under consideration. A graph theory approach was employed for calculating the eigenvalues of a large flexible system by reducing the system (stiffness) matrix to lower ordered submatrices. The related reachability matrix and term rank concepts are used to verify controllability and can be more effective than the alternate numerical rank tests. Control laws were developed for the shape and orientation control of the orbiting flexible shallow shell and numerical results presented

Viscosities of Binary Liquid Mixtures of Carbon Tetrachloride with Toluene & Xylenes

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Violation of Bell's inequality for phase singular beams

We have considered optical beams with phase singularity and experimentally verified that these beams, although being classical, have properties of two mode entanglement in quantum states. We have observed the violation of Bell's inequality for continuous variables using the Wigner distribution function (WDF) proposed by Chowdhury et al. [Phys. Rev. A \textbf{88}, 013830 (2013)]. Our experiment establishes a new form of Bell's inequality in terms of the WDF which can be used for classical as well as quantum systems.Comment: 7 pages, 9 figures and 1 tabl

Induced Gynogenesis in the Indian Major Carp, Cirrhinus mrigala (Ham.)

Artificial production of gynogenetic Cirrhinus mrigala (mrigal ) is reported for the first time. Ultraviolet irradiated Cyprinus carpio (common carp) milt was used for activating mrigal eggs. Cold shocking at 12°C and heat shocking at 39°C were used for restoring diploidy in activated eggs. Heat shock appeared more effective

Prevalence of tobacco use among adults in South Africa: Results from the first South African National Health and Nutrition Examination Survey

Background. Data on tobacco use have informed the effectiveness of South Africa (SA)’s tobacco control strategies over the past 20 years.Objective. To estimate the prevalence of tobacco use in the adult SA population according to certain demographic variables, and identify the factors influencing cessation attempts among current smokers.Methods. A multistage disproportionate nationally representative stratified cluster sample of households was selected for the South African National Health and Nutrition Examination Survey, conducted in 2012. A sample of 10 000 households from 500 census enumerator areas was visited. A detailed questionnaire was administered to all consenting adults in each consenting household.Results. Of adult South Africans, 17.6% (95% confidence interval (CI) 6.3 - 18.9) currently smoke tobacco. Males (29.2%) had a prevalence four times that for females (7.3%) (odds ratio 5.20, 95% CI 4.39 - 6.16; p<0.001). The provinces with the highest current tobacco smoking prevalence were the Western Cape (32.9%), Northern Cape (31.2%) and Free State (27.4%). Among current tobacco smokers, 29.3% had been advised to quit smoking by a healthcare provider during the preceding year, 81.4% had noticed health warnings on tobacco packages, and 49.9% reported that the warning labels had led them to consider quitting.Conclusion. A large proportion of adult South Africans continue to use tobacco. While considerable gains have been made in reducing tobacco use over the past 20 years, tobacco use and its determinants need to be monitored to ensure that tobacco control strategies remain effective