Effect of radial profile of a charged particle pulse on the electromagnetic wake in a plasma †

The variation of the self-magnetic field of a charged particle pulse penetrating a uniform homogeneous plasma is studied as a function of the charge density profile of the pulse.     

Effect of Mo Addition on Structure and Magnetocaloric Effect in γ-FeNi Nanocrystals

Nanocrystalline powders of (Fe₇₀Ni₃₀)_100?x Mo _x (x = 1 to 4) were produced by high-energy (SPEX) mechanical alloying. Increasing the Mo content was found to stabilize the face-centered cubic phase in mechanically alloyed nanopowders. To obtain a single γ-phase, a powdered sample was solution annealed in the γ-phase field and water quenched. The Curie temperature, T _C, of the alloys was lowered with Mo addition, without decreasing the refrigeration capacity (RC), due to the additional temperature broadening of the magnetic entropy change. Based on previous study on the role of disorder, the additional temperature broadening was attributed to increased positional disorder and changes in the distribution of ferromagnetic exchange bonds introduced by Mo addition into the γ-FeNi system. (Fe₇₀Ni₃₀)₉₇Mo₃ and (Fe₇₀Ni₃₀)₉₆Mo₄ alloys have RC_FWHM values of ～440 J/kg and ～432 J/kg at 5 T, comparable to other prominent magnetic refrigerants operating near room temperature. The economic viability of these alloys, along with their competitive magnetocaloric properties and potential for scalable production, make them good candidate magnetic refrigerants without critical rare-earth materials.     

Effect of Film Thickness on Properties of a—Si：H Films

The a -Si:H film with different thickness smaller than 1μm were deposited by plasma enhanced chemical vapor deposition (PECVD) under the optimum deposition contitions.The effect of diferent thickness on film properties is analyzed.The results show that,with the increase of the film thickness,the dark conductivity ,photoconductivity and threshold voltage increase,the optical gap and peak ratio of TA to TO in the Raman spectra decrease, the refractive index keeps almost constant, and the optical absorption coefficient and current ration of on/off state first maximize and then reduce.     

Mitigation of channel estimation error in TR–UWB system based on a novel MMSE equalizer

The time reversal (TR) technique combined with the ultra-wideband (UWB) system offers a new potential for decreasing the cost and complexity of the UWB receivers. In spite of TR–UWB's good performance in perfect channel state information (CSI), it is very sensitive to the channel estimation error. The effect of channel imperfection on the TR–UWB system is considered in this paper. At first, based on a minimum mean square error (MMSE) equalizer receiver, a prefilter is calculated in closed form to improve the performance of the TR–UWB system in an imperfect CSI scenario. Furthermore, for comparison purposes, a similar calculation for prefilter is carried out based on a simple matched filter (MF) receiver. Then, in order to improve the MF receiver performance, a two-stage iteration-based algorithm is developed. The initial value for this iteration-based improved algorithm is considered to be a prefilter which is calculated in the TR–UWB system with MMSE equalizer. This optimized algorithm causes the channel estimation error in the TR–UWB system to become zero in some steps. Finally, exhaustive simulations are done to demonstrate the performance advantage attained by the improved algorithm.     

Design of airport wake vortex monitoring system based on 1.5-μm pulsed coherent Doppler lidar

To shun the vortex hazard,the airport wake vortex monitoring system based on 1.5-mm pulsed coherent Doppler lidar is designed successfully in this paper.Based on the realistic analytical model,the wake vortex generated by airbus A340 under typical flight condition is simulated.Then the principle of airport wake vortex monitoring is introduced,and the work flow of the monitoring system is also presented.Moreover,based on the mechanism of vortex coherent detection and typical system parameters,both detection SNR and detection precision are obtained through numerical simulations.When the system outputs 2 J energy,the coherent detection SNR at 10 km distance is up to 23.452,and detection precision can reach 0.328 m/s.With the wake vortex monitoring experiment of A340,some vortex parameters are estimated.Due to these results comparatively coinciding with the previous simulation conclusions,the ability of Doppler lidar for full-scale wake vortex characterization and real time measurement is demonstrated.The study shows that the wake vortex detection based on 1.5-mm pulsed coherent Doppler lidar has the advantages of high accuracy and far distance,and the designed airport wake vortex monitoring system has proved to be effective and feasible,which has significant development and application prospect in the aspect of assuring flight security and increasing airport capacity.     

The Effect of Temperature on the Ionization Coefficient in Silicon†

The avalanche breakdown of p-n junction diodes across their space charge regions is known to be analogous to the Townsend mechanism for gases. Electric charge carriers, which gain sufficient energy from the field, are able to produce secondary electron-hole pairs. Both the holes and the electrons can themselves have ionizing collisions and thus the process leads to an avalanche. An important factor, controlling the breakdown, is the ionization coefficient a, defined as the number of electron-hole pairs produced by a carrier moving unit distance in the direction of the field.

This paper presents the results of nn investigation into the effect of lattice temperature on the ionization coefficient. This has been achieved by observing the breakdown voltage of a range of silicon diodes with either step or linear graded junctions, and applying simple and well-known relationships between ionization coefficient and breakdown voltage.

Measurements have been made over the temperature range 77 to 400°K, and for field strengths from 4 to 9 × 10⁵ volts/cm. Results show the ionization to become more efficient with decrease in temperature over this range of field strength. Temperature is found to have a greater effect at the lower field strength. This is shown to be consistent with modern theory.     

Effect of junction heating on the magnetocurrent in semiconductor diodes†

The effect of junction heating on the temperature dependence of magnetocurrent in semiconductor diodes is explained by taking into account the temperature dependence of various diode parameters.     

Effect of a Nanodimensional Polyethylenimine Layer on Current–Voltage Characteristics of Hybrid Structures Based on Single-Crystal Silicon

In this paper the study of the tunneling current–voltage (I–V) characteristics of silicon surfaces with n- and p-type conductivity as a function of roughness in the presence of an adsorbed insulating layer of polyethylenimine (PEI) is presented. A new approach is proposed for analysis of the tunnel current–voltage characteristics of a metal–insulator–semiconductor structure based on the combination of two models (Simmons and Schottky). Such joint analysis demonstrates the effect of surface states and evaluates changes in the band bending and electron affinity after the deposition of the polyelectrolyte layer on the semiconductor surface. As a result, we are able to differentiate between the equilibrium tunnel barrier (qφ ₀) and the barrier height (qφ _B). It is shown that the deposition of the polymer leads to an increase of the equilibrium tunnel barrier by more than 250 meV, irrespective of the roughness and the conductivity type of the silicon substrate. The PEI deposition also leads to changes in the barrier height (less than 25 meV) that are smaller than the equilibrium tunnel barrier changes, indicating pinning of the Fermi level by the electron surface states that are energetically close to it. These surface states can trap charge carriers, a process leading to the formation of a depletion region and band bending on the semiconductor surface. Moreover, the change in the barrier height qΔφ _B depends on the conductivity type of the semiconductor, being positive for n-type and negative for p-type, in contrast to qΔφ ₀, which is positive for all substrates. The change is explained by capture of electrons preferably from the semiconductor space-charge region in the presence of a cationic polyelectrolyte, e.g., PEI.     

Effect of a policy intervention on handset subsidies on the intention to change handsets and households’ expenses in mobile telecommunications

This study examined effect of a policy intervention that provides an upper limit for handset subsidies on users’ intention to change handset and households’ expenses on mobile telecommunications. The Korean government has prohibited mobile network providers from providing excessive subsidies for mobile handsets to attract subscribers since Nov. 2014 according to the mobile act. Using the exogenous variation, we estimate the impact of the policy on the intention to change handsets and expenses on handset installment, total mobile communications, and online content. The longitudinal data are from the 2014 to 2015 waves of the Korea Media Panel Survey. The mobile act lowered the predicted probability of switching handsets by 0.4% points. Moreover, the mobile act increased the predicted probability of any expense on handset installment by 7.5% points and had a significant impact on the amount of expenses on handset installment, with an increase of 7.8%. The mobile act lowered users’ willingness to switch handsets and increased spending on handset installment. This increased burden in handset installment might shrink the online content market, which has a large need for government support, as well as decrease consumers’ welfare. We assert that the policy intervention on handset subsidies is questionable with regard to both consumer welfare and the healthiness of the ICT ecosystem.     

Effect of γ-ray Radiation on the Loss of Optical Fiber in Visible Range

The mechanism of γ-ray radiation induced absorption loss of the optical fiber in visible range is analyzed. According to the mechanism, the quantitative relation between loss in optical fiber and γ-ray cumulation dose is found by use of methods of solid physics and statistic physics. This quantitative relation is certified in terms of the results of radiation experiment.     

Effect of γ—ray Radiation on Loss of Optical Fiber in Visible Range

The mechanism of γ-ray radiation induced absorption loss of the optical fiber in visible range is analyzed.According to the mechanism,the quantitative relation between loss in optical fiber and γ-ray cumulation dose is found by use of methods of solid physics and statistic physics.This quantitatie relation is certified in terms of the results of radiation experiment.     

Effect Investigation of Channel Estimation Deviation on STBC Performance in CDMA System

1　Introduction　Inrecentyears ,Space Timecode (STC) [3,8～ 11] hasattractedmuchattentionfrommanyscholarsinthefieldofwirelesscommunicationsasaneffectivetransmitdi versitytechniquecombatingfadinginwirelesscommuni cations.SpaceTimeBlockCode (STBC) [3] ,whichisproposedbyS .M .Alamoutiin 1998asasub optimaltransmitdiversitytechnique ,canobtain gainthroughemployingtwoantennasattransmitend .However,STBChastheassumptionofflatfadingchannelcondi tionthatlimitsitsuseonbroadbandwirelesscommuni cat…     

Effect of weak r.f. signal on the electron energy distribution in a gas discharge†

The electron energy distribution near the cylindrical anode surface of a discharge in air at low pressure is determined between a central wire and the cylindrical anode with and without a weak superimposed r.f. signal, using a linear electrostatic field analyser. The distribution, essentially of the Maxwell—Boltzmann type, undergoes appreciable alteration, especially in the high energy range, in the presence of a r.f. voltage. It is suggested that effectively a change in the mean total ionization cross section of the neutral molecules for electron impacts may account for the observed effect.     

Moderating effect of learning styles on a learning management system’s success

This study uses the DeLone and McLean model to determine the moderating impact of learning styles on the success of learning management systems from a student’s point of view. The main objectives of this research are: (1) to evaluate the Delone and McLean model of information system success in the context of learning management systems and, (2) to determine the effect of the learning styles of students on this model. An in-person survey of 258 engineering students was used to evaluate the research model. The analysis is based on structural equation modelling, specifically partial least squares. The results indicate that the research model explains use, user satisfaction, and perceived benefits of a learning management system. In addition, the Felder-Silverman learning styles (sensing-intuitive, visual-verbal; active-reflective; sequential-global) modify the strength of the relationships between the variables of the success model.     

Experimental study on the evolution of bright-dark pulses in a 2 μm mode-locked thulium/holmium co-doped fiber laser

We experimentally demonstrate the effects of pump power and polarization state on the evolution of bright-dark pulses (BDPs) in a figure-eight passively mode-locked thulium/holmium co-doped fiber laser (THDFL) using nonlinear amplifying loop mirror (NALM) technology. As the pump power increases from 0.5 W to 1 W, the BDPs are separated and exhibit a linear increase in the time interval between the bright pulse (BP) and dark pulse (DP), which roughly corresponds to the reciprocal of the modulation frequency in the radio frequency (RF) spectrum. Additionally, the polarization state in the cavity is altered by adjusting the polarization controller (PC), and the central wavelength of spectrum, pulse waveform, and full width at half maximum (FWHM) of BDPs in different states are presented.     

Effect of intrachain configuration disorder on the exciton delocalization in π-conjugated polymers

Exciton delocalization in conjugated polymers is investigated in view of its important contribution to the ultrafast charge separation recently focused in polymer solar cells (PSCs). Simulations are performed within the framework of an extended version of the one-dimensional Su-Schrieffer-Heeger (SSH) model with different molecular configuration disorders considered, including transfer integral disorder and on-site energy disorder. To quantitatively describe the exciton delocalization degree, we introduce the exciton binding energy in the numerical calculations. It is found that both the transfer integral and on-site energy disorders can effectively reduce the exciton binding energy, indicating that they should play crucial roles in facilitating the exciton delocalization. Especially, there exists a critical strength for either of the two disorder forms, beyond which only by the internal electric field in PSCs, a photogenerated exciton can be dissociated, consequently contributing to the ultrafast charge separation. In addition, we take the temperature dependent lattice vibration as an example to quantitatively discuss the realization possibility of the critical disorder strength.     

Study of the effects of structural uncertainties on a fractional system of the first kind – application in vibration isolation with the CRONE suspension

In this paper, we deal with the effects of the uncertainties on a fractional system of the first kind, mainly on the frequency-domain and the time-domain responses. For the structural uncertainties, two main aspects are studied: the nonlinearities of the physical components used to realize the fractional system and the consideration of the previously neglected dynamics of the system. Both uncertainties are introduced for the hydropneumatic CRONE suspension, previously synthesized and realized without taking into consideration these uncertainties. So, the novel approach treated in this work is to find whether the uncertainties, which were previously neglected in the synthesis and the realization phases, alter the behaviour of the system or not. The results show that the fractional order system behaviour is not affected.