突出盲峒自然火灾的处理

论述了救护大队在处理建新矿1010顺槽突出盲峒发生瓦斯浓度达到爆炸界限与自燃阴火源同时存在的事故中,采取控风、注水方法灭火,取得良好的效果.     

采用ASIC技术的新一代电流传感器

为了满足电力电子行业电流测量精度的要求,LEM公司开发了新一代开环霍尔效应电流传感器。本文介绍了该电流传感器的性能特点。     

The influence of drift fields in thin silicon solar cells

The influence of electric “drift” fields in the base of silicon solar cells on device performance is investigated. The drift fields are the result of a nonuniform dopant density in the base material. Numerical modelling is carried out for a range of representative cell structures and two different models for the dependence of the minority carrier lifetime on the dopant density. The cell design variables, in particular the dopant densities and the thicknesses of the device regions, are optimized with respect to the cell efficiency. Comparison of optimized cells incorporating a drift field with those not having a drift field, shows that a drift field can offer only small efficiency advantages for particular cell structures and recombination parameters, and only if large variations in dopant concentration can be achieved.     

Charge density at the contacts of symmetric and asymmetric organic diodes

The organic diode, or metal-organic-metal (MOM) structure, is constituent key building block of organic-devices. The physical understanding and performance evaluation of these devices usually require proper modeling and simulation of the metal-organic structure. A topic of major concern in the simulation of the MOM structure, although frequently mishandled, is the selection of proper boundary conditions at the metal-organic interface. In this work, we determine the boundary conditions for the charge density at the metal-organic contact. Symmetric and asymmetric organic diodes with unipolar and bipolar conduction are analyzed. Using experimental current-voltage curves, an analytical method to determine the value of the charge density at the contacts is proposed. In single-carrier diodes, we observe that the charge concentration at the interface due to injection follows a power-law function of the current in metal-organic contacts in drift-dominated transport. This boundary condition is the way to introduce the contact effects in models. The contact affects the other regions (e.g., the bulk) as a boundary condition. This boundary condition for the charge density keeps information about the limited recombination velocity at the contacts and the contribution from space charge limited conduction (SCLC) in the bulk. In diffusion-dominated transport, at low bias close to the diode’s built-in voltage, the charge density at the contact is almost constant with the current. The complete relation between charge and current for injecting electrodes, extracted from the analysis of single-carrier diodes, can be used as boundary condition in bipolar devices.     

基于全局最优的快速一致性点漂移算法

目前受到广泛关注和研究的一致性点漂移(CPD)算法是一种基于高斯混合模型的点模式匹配算法,虽然该算法具有较强的鲁棒性,但其存在局部最优性和收敛速度随点集大小增加而下降等问题。针对上述问题,该文提出了一种新的基于全局最优的快速一致性点漂移算法。该算法首先将点集进行正交标准形约简,利用约简后点集的重要性质,推导出不完全观测数据的对数似然函数在全局最优解附近凸函数区域的边界值,再以该边界值为基础,采用多重初始化策略来实现全局最优。最后,提出了基于置信域的全局收敛二次平方迭代期望最大化算法,实现了全局优化算法的超线性收敛。模拟仿真与真实数据实验验证了该文算法是有效的、快速的以及鲁棒性较强的。     

One-dimensional drift-flux model for two-phase flow in a large diameter pipe

In view of the practical importance of the drift-flux model for two-phase-flow analysis in general and in the analysis of nuclear-reactor transients and accidents in particular, the distribution parameter and the drift velocity have been studied for vertical upward two-phase flow in a large diameter pipe. One of the important flow characteristics in a large diameter pipe is a liquid recirculation induced at low mixture volumetric flux. Since the liquid recirculation may affect the liquid velocity profile and promote the formation of cap or slug bubbles, the distribution parameter and the drift velocity in a large diameter pipe can be quite different from those in a small diameter pipe where the liquid recirculation may not be significant. A flow regime at a test section inlet may also affect the liquid recirculation pattern, resulting in the inlet-flow-regime dependent distribution parameter and drift velocity. Based on the above detailed discussions, two types of inlet-flow-regime dependent drift-flux correlations have been developed for two-phase flow in a large diameter pipe at low mixture volumetric flux. A comparison of the newly developed correlations with various data at low mixture volumetric flux shows a satisfactory agreement. As the drift-flux correlations in a large diameter pipe at high mixture volumetric flux, the drift-flux correlations developed by Kataoka-Ishii, and Ishii have been recommended for cap bubbly flow, and churn and annular flows, respectively, based on the comparisons of the correlations with existing experimental data.     

铜绿山矿软岩巷道支护的实践

根据铜绿山矿井下软岩巷道的支护情况,分析了岩层破坏的原因,并提出了改善支护状态的途径和保障安全的措施     

分条式上向进路块石混凝土胶结充填采矿法的应用

在会东铅锌矿二期扩建工程投产前,露天开采的矿石品位低,于是在井下开采中应用分条式上向进路充填采矿法先采出部分富矿,以满足冶炼厂对原料的要求,同时,也可对矿山还贷和提高经济效益起到一定的作用。作者对此采矿方法在会东矿的应用作了较详细的介绍。     

Origin of high fill factor in polymer solar cells from semiconducting polymer with moderate charge carrier mobility

The fill factor of polymer bulk heterojunction solar cells (PSCs), which is mainly governed by the processes of charge carrier generation, recombination, transport and extraction, and the competition between them in the device, is one of the most important parameters that determine the power conversion efficiency of the device. We show that the fill factor of PSCs based on thieno[3,4-b]-thiophene/benzodithiophene (PTB7):[6,6]-phenyl C₇₁-butyric acid methylester (PC₇₁BM) blend that only have moderate carrier mobilities for hole and electron transport, can be enhanced to 76% by reducing the thickness of the photoactive layer. A drift–diffusion simulation study showed that reduced charge recombination loss is mainly responsible for the improvement of FF, as a result of manipulating spatial distribution of charge carrier in the photoactive layer. Furthermore, the reduction of the active layer thickness also leads to enhanced built-in electric field across the active layer, therefore can facilitate efficient charge carrier transport and extraction. Finally, the dependence of FF on charge carrier mobility and transport balance is also investigated theoretically, revealing that an ultrahigh FF of 80–82% is feasible if the charge mobility is high enough (∼10⁻³–10⁻¹ cm²/V s).     

Fault curves—A novel drift-fault diagnosing method for condition monitoring

A drift-fault diagnosing method is presented based on fault curves fitted to changes in a single characteristic of a system performance curve such as the peak of the step response. The method consists of fitting a fault curve, for each potential fault in the system, to samples of the characteristic produced under different levels of the faults. Unknown faults are then diagnosed, irrespective of severity, by seeing which fault curve is closest to the characteristic produced by the system under test. It is argued that this method is very appropriate for diagnosing faults detected by condition monitoring systems since these will be drift faults, and because the method can be applied to normal operational signals without the need to inject special test signals.