Current–voltage and capacitance–voltage characteristics of Al Schottky contacts to strained Si-on-insulator in the wide temperature range

The electrical characteristics of Al/strained Si-on-insulator (sSOI) Schottky diode have been investigated using current–voltage (I–V) and capacitance–voltage (C–V) measurements in the wide temperature range of 200–400 K in steps of 25 K. It was found that the barrier height (0.57–0.80 eV) calculated from the I–V characteristics increased and the ideality factor (1.97–1.28) decreased with increasing temperature. The barrier heights determined from the C–V measurements were higher than those extracted from the I–V measurements, associated with the formation of an inhomogeneous Schottky barrier at the interface. The series resistance estimated from the forward I–V characteristics using Cheung and Norde methods decreased with increasing temperature, implying its strong temperature dependence. The observed variation in barrier height and ideality factor could be attributed to the inhomogeneities in Schottky barrier, explained by assuming Gaussian distribution of barrier heights. The temperature-dependent I–V characteristics showed a double Gaussian distribution with mean barrier heights of 0.83 and 1.19 eV and standard deviations of 0.10 and 0.16 eV at 200–275 and 300–400 K, respectively. From the modified Richardson plot, the modified Richardson constant were calculated to be 21.8 and 29.4 A cm⁻² K⁻² at 200–275 and 300–400 K, respectively, which were comparable to the theoretical value for p-type sSOI (31.6 A cm⁻² K⁻²).     

测井曲线标准化方法研究

由于长岭凹陷区经过近60年的勘探开发,再加上井场井眼条件的差异、测井系列、仪器刻度、测量时间及操作者不同等因素,使得各测井曲线存在系统误差。因此在开展储层参数研究和有效厚度划分时,为消除这些非地层因素对原始资料的影响,有必要对测井曲线进行标准化,以保证解释结果的合理性与可靠性。测井曲线标准化方法可以分为定性和定量两种类型。其中定性方法主要包括直方图法标准化校正、均值法标准化校正和重叠图法标准化校正;定量方法则为趋势面分析校正法。本论文利用Matlab软件,采用趋势面方法对研究区域内的井进行测井曲线标准化。结果表明经过趋势面法标准化校正能够消除不利因素,准确的提取出测井曲线中的各种有用地质信息。     

NIOSH national survey of long-haul truck drivers: Injury and safety

Approximately 1,701,500 people were employed as heavy and tractor-trailer truck drivers in the United States in 2012. The majority of them were long-haul truck drivers (LHTDs). There are limited data on occupational injury and safety in LHTDs, which prompted a targeted national survey. The National Institute of Occupational Safety and Health conducted a nationally representative survey of 1265 LHTDs at 32 truck stops across the contiguous United States in 2010. Data were collected on truck crashes, near misses, moving violations, work-related injuries, work environment, safety climate, driver training, job satisfaction, and driving behaviors. Results suggested that an estimated 2.6% of LHTDs reported a truck crash in 2010, 35% reported at least one crash while working as an LHTD, 24% reported at least one near miss in the previous 7 days, 17% reported at least one moving violation ticket and 4.7% reported a non-crash injury involving days away from work in the previous 12 months. The majority (68%) of non-crash injuries among company drivers were not reported to employers. An estimate of 73% of LHTDs (16% often and 58% sometimes) perceived their delivery schedules unrealistically tight; 24% often continued driving despite fatigue, bad weather, or heavy traffic because they needed to deliver or pick up a load at a given time; 4.5% often drove 10 miles per hours or more over the speed limit; 6.0% never wore a seatbelt; 36% were often frustrated by other drivers on the road; 35% often had to wait for access to a loading dock; 37% reported being noncompliant with hours-of-service rules (10% often and 27% sometimes); 38% of LHTDs perceived their entry-level training inadequate; and 15% did not feel that safety of workers was a high priority with their management. This survey brings to light a number of important safety issues for further research and interventions, e.g., high prevalence of truck crashes, injury underreporting, unrealistically tight delivery schedules, noncompliance with hours-of-service rules, and inadequate entry-level training.     

Fundamental analysis of recombinant human epidermal growth factor in solution with biophysical methods

Correlation of thermodynamic and secondary structural stability of proteins at various buffer pHs was investigated using differential scanning calorimetry (DSC), dynamic light scattering (DLS) and attenuated total reflection Fourier-transform infrared spectroscopy (ATR FT-IR). Recombinant human epithelial growth factor (rhEGF) was selected as a model protein at various pHs and in different buffers, including phosphate, histidine, citrate, HEPES and Tris. Particle size and zeta potential of rhEGF at each selected pH of buffer were observed by DLS. Four factors were used to characterize the biophysical stability of rhEGF in solution: temperature at maximum heat flux (T_m), intermolecular β-sheet contents, zeta size and zeta potential. It was possible to predict the apparent isoelectric point (pI) of rhEGF as 4.43 by plotting pH against zeta potential. When the pH of the rhEGF solution increased or decreased from pI, the absolute zeta potential increased indicating a reduced possibility of protein aggregation, since T_m increased and β-sheet contents decreased. The contents of induced intermolecular β-sheet in Tris and HEPES buffers were the lowest. Thermodynamic stability of rhEGF markedly increased when pH is higher than 6.2 in histidine buffer where T_m of first transition was all above 70?°C. Moreover, rhEGF in Tris buffer was more thermodynamically stable than in HEPES with higher zeta potential. Tris buffer at pH 7.2 was concluded to be the most favorable.     

Classification of quasigroups based on period factors

Edon80 is a stream cipher design that had advanced to the third and last phase of the eSTREAM project. The core of the cipher consists quasigroup string e-transformations and it employs four quasigroups of order 4. The employed quasigroups have influence on the period of the keystream. There are 576 quasigroups of order 4 in total which have different period factors. The four quasigroups used in Edon80 were chosen by numerous computer experiments. In this paper, based on permutation groups, we give a theory criterion for the determination of quasigroups and give a complete classification for the 576 quasigroups of order 4 according to their period factors.     

网络安全威胁因素及其常见网络安全技术分析

社会经济的快速发展促进了科学技术水平的显著提升，社会生产生活各个领域当中对计算机网络的应用程度不断提升，当前，网络已经成为了人们日常生活与工作的重要组成部分。为此，加强对网络安全等因素影响研究就显得格外重要。网络环境关系着用户的使用质量，更加影响人们的工作效率，加强对网络安全技术的研究时解决相关问题的核心内容。本文针对网络安全威胁因素以及常见的网络安全技术进行了简要分析。     

A new semi-empirical wind turbine capacity factor for maximizing annual electricity and hydrogen production

The capacity factor is an important wind turbine parameter which is ratio of average output electrical power to rated electrical power of the wind turbine. Another main factor, the AEP, the annual energy production, can be determined using wind characteristics and wind turbine performance. Lower rated power may lead to higher capacity factor but will reduce the AEP. Therefore, it is important to consider simultaneously both the capacity factor and the AEP in design or selecting a wind turbine. In this work, a new semi-empirical secondary capacity factor is introduced for determining a rated wind speed at which yearly energy and hydrogen production obtain a maximum value. This capacity factor is expressed as ratio of the AEP for wind turbine to yearly wind energy delivered by mean wind speed at the rotor swept area. The methodology is demonstrated using the empirical efficiency curve of Vestas-80 2 MW turbine and the Weibull probability density function. Simultaneous use of the primary and the secondary capacity factors are discussed for maximizing electrical energy and hence hydrogen production for different wind classes and economic feasibility are scrutinized in several wind stations in Kuwait.     

Identification of Wiener systems based on the variable forgetting factor multierror stochastic gradient and the key term separation

The identification of Wiener systems is very difficult because of the output nonlinearity and the parameter product term. To identify the Wiener system, a novel stochastic gradient algorithm based on the multierror and the key term separation is proposed. Firstly, the Wiener system is parameterized as a pseudo-linear model to avoid the products of the parameters. Secondly, a parzen window is used to estimate the probability density function of the error. Thirdly, a stochastic information gradient algorithm with the multierror is adopted to estimate the parameters. The multierror takes the place of the scalar error by the stacked error, which accelerates the algorithm greatly. Fourthly, a variable forgetting factor considering errors is integrated to further speed the algorithm up. Finally, the proposed algorithm is validated by a numerical example and an industrial case. The estimation results indicate that the proposed algorithm can obtain accurate estimates with fast convergence speed.     

Reduction of Ripple Current Loss by Electromagnetic Coupling of Air‐Core Reactors

To reduce the loss due to ripple current in a multiphase current‐reversible chopper, we investigated electromagnetic coupling of an air‐core reactor. We derived the relationship between the amplitude of the ripple current, the duty factor, and the electromagnetic coupling coefficient, and used the results to estimate the effects of electromagnetic coupling in the design of a train energy storage system. We built reactors with electromagnetic coupling coefficients of 0.93 and 0.60. These reactors employed a new winding structure that provides an optimal electromagnetic coupling coefficient. The mass of the former type of reactor was increased by 4.4% over the conventional design, and that of the latter type of reactor was decreased by 17%. Finally, we tested the new reactors. When the chopper employs the former type of reactor and operates with equal‐phase switching and cumulative coupling, the loss due to ripple current is decreased by 11%. When the chopper employs the latter type of reactor and operates with shift‐phase switching and differential coupling, the loss is decreased to 31%. The test showed that the calculated relationships agreed with the measured values.