用于HVDC的电子式直流互感器的可靠性预计

直流互感器是高压直流输电工程中的重要设备,电力系统要求其具有较高的可靠性。为此在简要介绍了电子式直流互感器的系统结构后建立了它的可靠性框图和数学模型并推导出其失效率和平均无故障时间的数学表达式;根据美国军标MIL-HDBK-217F修订通告2和我国军标GJB/Z299-1998用计数法和应力法预计得出电子式直流互感器的失效率为15.51×(106h)-1,平均无故障时间为64474h,且指出激光器的失效率是影响整机可靠性的主要因素。     

基于神经网络的电子战人力资源规划分析

从现代智能化战争的电子战人力资源需求角度出发,分析了现代智能化战争中电子战人力资源规划问题,提出了基于神经网络理论的电子战人力资源规划分析思路和建议.其次,建立了兵力需求规划模型、BP神经网络和RBF神经网络预测模型以及电子战人员补充模型,将以往以定性分析为主的问题进行定量求解.最后,通过实际人员数量算例对模型进行分析...     

NMR Structure and Biophysical Characterization of Thermophilic Single-Stranded DNA Binding Protein from Sulfolobus Solfataricus

Proteins from Sulfolobus solfataricus (S. solfataricus), an extremophile, are active even at high temperatures. The single-stranded DNA (ssDNA) binding protein of S. solfataricus (SsoSSB) is overexpressed to protect ssDNA during DNA metabolism. Although SsoSSB has the potential to be applied in various areas, its structural and ssDNA binding properties at high temperatures have not been studied. We present the solution structure, backbone dynamics, and ssDNA binding properties of SsoSSB at 50 °C. The overall structure is consistent with the structures previously studied at room temperature. However, the loop between the first two β sheets, which is flexible and is expected to undergo conformational change upon ssDNA binding, shows a difference from the ssDNA bound structure. The ssDNA binding ability was maintained at high temperature, but different interactions were observed depending on the temperature. Backbone dynamics at high temperature showed that the rigidity of the structured region was well maintained. The investigation of an N-terminal deletion mutant revealed that it is important for maintaining thermostability, structure, and ssDNA binding ability. The structural and dynamic properties of SsoSSB observed at high temperature can provide information on the behavior of proteins in thermophiles at the molecular level and guide the development of new experimental techniques.     

Influence diagnostics for multivariate GARCH processes

This article presents diagnostics for identifying influential observations when estimating multivariate generalized autoregressive conditional heteroscedasticity (GARCH) models. We derive influence diagnostics by introducing minor perturbations to the conditional variances and covariances. The derived diagnostics are applied to a bivariate GARCH model of daily returns of the S&P500 and IBM. We find that univariate diagnostic procedures may be unable to identify the influential observations in a multivariate model. Importantly, the proposed curvature‐based diagnostic identified influential observations where the correlation between the two series had a major change. These observations were not identified as influential using the univariate diagnostics for each asset separately. When estimating the bivariate GARCH model allowing for weights at influential observations, we found that the time‐varying correlations behaved differently from that implied by the model ignoring influential observations. The application therefore highlights the importance of extending univariate diagnostic procedures to multivariate settings.     

Analysis of volatile compounds in L. edodes blanched by hot water and microwave

The comprehensive flavour characterisation and volatile compounds of raw L. edodes, hot water blanching (HB) sample and microwave blanching (MB) sample were comparatively analysed by electronic nose technology and headspace solid‐phase micro‐extraction combined with gas chromatography‐mass spectrometry (HS‐SPME‐GC‐MS). Results indicated that volatile components in L. edodes markedly changed after HB and MB. Volatile compounds of raw L. edodes consisted mainly ketones, sulphide and alcohols, and 3‐octanone, as well as 1‐octen‐3‐one, were the major compounds. The content of ketones and sulphides in blanched samples markedly decreased, while the relative content of aldehydes, hydrocarbons and esters increased, which became the major volatile compounds of treatment samples. In addition, the percentage contents of esters, alcohols and sulphides in MB samples were significantly (P < 0.05) higher than that in HB samples, especially 1‐octen‐3‐ol, which contributes more to mushroom flavour. Therefore, MB is a better pretreatment method of L. edodes processing and cooking according to the results of experiment.     

An investigation on the dosimetric impact of hip prosthesis in radiotherapy

The objectives of this study are to evaluate the dosimetric impact of hip prosthesis using ELEKTA linac X-rays and compare the dose perturbations of metallic and nonmetallic hip prostheses. The local dose distributions of typical hip prostheses were calculated for 4, 8, and 15 MV beams by Geant4. Three prosthesis materials were selected in calculation to reveal the relation between material type and local dose perturbations of prostheses. Furthermore,the effect of nominal energy on prosthesis perturbation was also discussed and analyzed. Taking the calculated dose to the hip joint as reference, considerable differences were observed between prostheses and hip joints. In the prosthesis shadow region, the relative dose decreasing was up to 36, 21, and 16 % for the Co–Cr–Mo alloy, titanium alloy, and ceramic prostheses, respectively. In backscattering region, the relative dose increasing was about1–7 %. Overall, the results show that the dose perturbation effect of prostheses was mainly determined by material type, nominal energy, and density. Among these typical hip prostheses, ceramic prosthesis introduces the lowest dose perturbations.     

Simulation of runaway electron generation and diffusion during major disruptions in the HL-2A tokamak

The generation and diffusion of runaway electrons (REs) during major disruptions in the HL-2A tokamak has been studied numerically. The diffusion caused by the magnetic perturbation is especially addressed. The simulation results show that the strong magnetic perturbation (δB/B ∼ 1.0 × 10⁻³) can cause a significant loss of REs due to the radial diffusion and restrain the RE avalanche effectively. The results also indicate that the REs are generated initially in the plasma core during disruptions, and that the toroidal electric field does not exhibit a centrally hollow phenomenon. In addition, it is found that the toroidal effects have little impact on the generation of RE and the evolution of toroidal electric field.     

新型数码电子雷管及其起爆系统的开发与应用

针对现有数码电子雷管及其起爆系统在爆破作业现场使用中存在操作不便、输入延期时间繁琐和易错的问题,通过炮孔定位和数据采集技术,研发了新型数码电子雷管及其起爆系统。在使用过程中,可识别炮孔位置,自动匹配炮孔和雷管编号,自动写入延期时间,快速建立炮孔位-雷管ID码-延期时间三者的关系,各功能独立分开,但又相互配合,减少了误操作,提高了爆破作业现场自动化水平,增强了新型数码电子雷管起爆系统的安全性和可操作性。     

Study on soliton phase characteristics in 100 Gbps single‐channel telecommunication system

Here, we demonstrate the peculiar particle nature of soliton pulses with relative to phase, where the adjacent soliton pulses in a sequence attract and repel each other periodically for in‐phase and out‐of‐phase arrangement, respectively. This effect of soliton's interaction and repulsion is studied analytically by using perturbation theory approach. The study of soliton pair characteristics are mainly noted for different relative spacing (q _o ) between them and for different phase of launched soliton pulses. Following the analytical studies, we analyzed the effect in a 100 Gbps, single channel and uncompensated telecommunication system for different phased soliton sequences. Such that, the performance of the telecommunication system is characterized in terms of Q‐factor (Q) and bit‐error rate to realize the influence of phase on soliton pulses. The system was studied for 1 collision length (L _D ) of 123.36 km. It is seen that, for 100 Gbps system implemented with standard single mode telecom fiber, with soliton spaced at q _o  = 5.28, the in‐phase pulses interacted at 61.68 km, which has resulted in Q  = 0 (bit‐error rate  = 1). It is realized that for small‐phase introduction on soliton pulses, the system yielded fair Q demonstrating the non‐interaction at the I _p as the pulses deviate with respect to increasing phase values. But, it is also shown that large phase between pulses introduces more deviation, which results in overlapping of deviated pulses with adjacent pulses in sequence resulting in degradation of high bitrate system performance.