LED光源反射器特征参数对被照面照度的影响

在普通LED照明应用中,常采用多颗LED光源加装抛物线型反射器来满足照明要求。本文以9颗LED光源为例,探讨抛物线型反射器特征参数对被照面照度的影响。模拟结果表明：反射器长度不变,焦距越小,光能聚集效果越好;反射器口径不变,随着焦距的增大,被照面照度分布由光斑逐渐变为光环,中心照度逐渐降低;反射器焦距不变,随着口径的减小,被照面中心区域的照度几乎不变,但两侧的照度略有下降。在反射器口径面加装磨砂透光板后,被照面聚光区域的照度下降明显,但是被照面照度分布更加均匀;按环形排列方式增加LED光源的数目仅增大被照面的照度。     

Evaluating the Parameters of the Equivalent Circuit of Single-Phase Induction Motors

ABSTRACT

An algorithm is proposed in this paper which evaluates the equivalent-circuit parameters of single-phase induction motors. Two parameters are kept constant at all speeds: the resistance of the stator winding, and the resistance representing the core losses of the motor. All other parameters must vary with the speed of the motor, so that the equivalent circuit is able to match exactly the performance of the actual motor. The parameters are evaluated from standard test data taken at standstill, at no-load, and under load conditions.     

MnZn铁氧体单晶的硬度问题

用维氏显微硬度计测定了ＭｎＺｎ铁氧体单晶不同晶面方向的硬度。结果表明,对于利用布里兹曼法生长的ＭｎＺｎ铁氧体单晶来说,并不存在硬度方面的各向异性。     

Improvement of the energy efficiency in the decomposition of dilute trichloroethylene by the barrier discharge plasma process

In order to improve the energy efficiency in the dilute trichloroethylene (TCE) removal by the nonthermal plasma process, the barrier discharge reactor was studied experimentally. It is investigated by combining it with catalyst of manganese dioxide at the downstream of the barrier discharge reactor. Decomposition efficiency by the barrier discharge reactor was about 83% at the gas flow rate 2 L/min, where the dilute TCE concentration is 250 ppm. Decomposition efficiency with passing through manganese dioxide was improved about 99% at the specific energy of 40 J/L. However, other by-products including ozone and oxidation by-products such as DCAC and TCAA were detected by the gas chromatograph mass spectrometry or the Fourier transform infrared spectroscope measurement. DCAC is generated at the plasma reactor, but TCAA is generated at catalyst during ozone decomposition. CO/sub x/ yield increased about twice with passing through catalyst in the Direct Process. Nitric oxides such as NO, NO/sub 2/, and N/sub 2/O did not generate so much in this barrier discharge process. The dielectric barrier discharge process combined with manganese dioxide is considered as a very desirable way to improve the energy efficiency.     

硫酸盐还原菌的驯化及脱硫性能研究

对内蒙古某地工业污泥分离出的硫酸盐还原菌 (sulfate-reducing bacteria，SRB)-DYB2菌种进行 离子、电厂脱硫尾液的环境适应驯化并分别进行 脱除试验。首先采用3 000~9 000 mg/L的 驯化DYB2，在38 ℃、pH值为7.2、菌株接种量为10%及厌氧条件下，72 h后，溶液中 的去除率为69.5%~76.9%，净去除量为2 307~ 6 255 mg/L；改变菌株接种量，在38 ℃、pH值为7.2，处理含 1 000~4 000 mg/L的脱硫尾液。当接种量为20%时， 1 000 mg/L去除率最高，达到83.3%，净去除量最高达到2 140 mg/L。结果表明，接种量相同，脱硫尾液中 浓度增加，净去除量增加，但去除率降低；同浓度 脱硫尾液，接种量愈高，去除率与净去除量愈多。     

Study by laser interferometry of the resonance modes of the shear plate used in the standards characterization of piezoceramics

Recent Finite Element Analysis (FEA) modeling of a Standard shear plate of Navy II type PZT-based ceramics was carried out based on the full matrix material characterization Material coefficients in the linear range, including all losses, were obtained by an iterative automatic method from impedance measurements at resonance. FEA modeling has shown that the shear plate used in the standard characterization of piezoceramics is dynamically clamped at resonance, which results in an underestimation of the related shear coefficients. This work aims to examine experimentally the resonance modes of such standard shear sample by the use of the laser interferometry technique to map the displacement pattern at its free surfaces.     

铋元素对阀控式密封铅酸蓄电池作用的探讨

比较了美国RSR公司和中国江苏春兴集团制订的有关铅及铅合金化学组份、物理及机械性能的标准。就含铋铅粉及合金在VRLA蓄电池的作用进行了试验。研究表明 ,它们对电池的容量、比能量、大电流放电及低温容量均有一定的提高     

发电机中性点电压互感器断线的检测方法

分析了发电机中性点电压互感器断线故障对定子单相接地保护的影响,指出中性点电压互感器断线将导致三次谐波电压比值型定子单相接地保护误动,但现有电压互感器断线判断方法不易检测该处的断线故障。利用单相接地故障发生时机端和中性点三次谐波电压故障分量近似相同的变化特点区分中性点电压互感器断线与中性点金属性接地故障,防止定子单相接地保护误动。     

桥门式起重机吊重防摇状态反馈控制系统设计

为了防止桥门式起重机吊重在目标位置和期望时间时摇摆,针对电压控制直流电机驱动的小车吊重系统,建立了系统动力学方程,并在工程实用和允许范围内对该方程进行简化和状态空间描述.通过状态反馈控制,并考虑一对闭环主导极点,类似二阶系统性能分析推导出反馈控制器的调节参数公式.仿真结果表明小车在目标位置10 m、期望调节时间7s静止,同时吊重摆角衰减为零,控制系统具有良好的稳定性和期望的动态特性.     

正交实验在MH-Ni电池化成中的应用

介绍了利用正交试验的方法考察充电速率、充入电量以及放电速率对直封ONY1．2电池初期性能及1C循环寿命的影响。通过试验优化出合理、省时的化成制度：即第1次以0．5C5A充2h,停30min,以1C5A放电,第二次以0．5C5A充2h 50min,停30min,以1C5A放电。     

可编程序控制器在机床数控系统中应用探讨

可编程序控制器（简称PLC）是专为在工业环境中应用而设计的一种工业控制用计算机，具有抗干扰能力强、可靠性高、体积小等优点，是实观机电一体化的理想装置，目前在机械加工行业中的应用日益广泛。本文介绍的是永宏PLC在机床数控系统中应用的有关控制原理与方法，分析了控制系统在设计和使用中需要认识与解决的问题，给出了控制系统方案及软硬件结构的设计思路。     

New study of the abnormal behavior of the low temperature dependence of the current in inhomogeneous Schottky diode

In this study, we show clearly why unexpected observations have been reported in the current–voltage curves of Schottky diodes, containing barrier inhomogeneities generated by using the analytical results based on a Gaussian distribution model of barrier heights. The Chand's calculations have shown that the current (saturation current) at low temperatures may exceed the current (saturation current) at high temperatures when the effective barrier height is calculated from an appropriate integral with integration limits −∞ and +∞. In this new study, we show that the method followed by Chand to remove these anomalies is not accurate enough. We prove that the origin of these anomalies stems from the nature of a proper function f(φ) that moves to the negative barrier heights and takes large value of the integral at low temperatures than at high temperatures when it has large standard deviation (σ) and the discrepancies are not due to the integration limits as Chand concluded. In order to obtain results consistent with the thermionic emission–diffusion theory, the standard deviation must have lower values. Copyright © 2014 John Wiley & Sons, Ltd.     

煤灰熔融特性与锅炉安全运行平衡关系探讨

锅炉的安全运行与煤的品质密切相关。其要点是煤的热值,煤灰的熔融特性以及炉膛的中心温度。当煤燃烬后炉膛的中心温度、煤灰具有的熔融特性对锅炉的安全运行起着重要的作用。按比例配煤是通过不同种类的煤,调整煤燃烬后煤灰所具有的熔融特性以达到锅炉安全运行。     

Results of experimental studies of the gas-dynamic behavior of airflow in the circulation line of the air condenser of steam-turbine plants

The results of experimental studies and a physical model of the three-dimensional flow of cooling air in the circulation line (CL) of a dummy air condenser (AC) incorporating a fan, heat-exchange modules, a shell, and other auxiliary components are analyzed. The local air velocity fields determined experimentally at the AC CL inlet and at the fan diffuser outlet are presented. The guidelines for determining the head-capacity characteristics of the airflow through the AC CL are proposed.     

辐照交联乙烯四氟乙烯绝缘电线后处理工艺条件的选择

对辐照交联乙烯四氟乙烯绝缘电线在不同条件下进行了后处理,并对后处理后的样品进行物理机械性能和热性能的试验,发现在真空环境中与在空气环境中进行后处理对样品主要性能的影响基本相同。在120℃、160℃、200℃下不同时间处理的结果显示,较低温度长时间后处理与较高温度短时间后处理可以认为是等效的。     

新建机组抗燃油系统冲洗问题探讨

针对邹县发电厂新建1000MW超超临界机组抗燃油系统冲洗过程的问题进行了分析,提出防范措施。     

山东电网制氢站制氢系统的现状及改进

本文对山东电网制氢站制氢系统设备运行现状进行了论述，并对设备、运行的改进及气体分析监督提出改进建议供制氢站运行人员参考。     

Estimation of Efficiency of the Cooling Channel of the Nozzle Blade of Gas-Turbine Engines

The main direction of improvement of gas-turbine plants (GTP) and gas-turbine engines (GTE) is increasing the gas temperature at the turbine inlet. For the solution of this problem, promising systems of intensification of heat exchange in cooled turbine blades are developed. With this purpose, studies of the efficiency of the cooling channel of the nozzle blade in the basic modification and of the channel after constructive measures for improvement of the cooling system by the method of calorimetry in a liquid-metal thermostat were conducted. The combined system of heat-exchange intensification with the complicated scheme of branched channels is developed; it consists of a vortex matrix and three rows of inclined intermittent trip strips. The maximum value of hydraulic resistance ξ is observed at the first row of the trip strips, which is connected with the effect of dynamic impact of airflow on the channel walls, its turbulence, and rotation by 117° at the inlet to the channels formed by the trip strips. These factors explain the high value of hydraulic resistance equal to 3.7–3.4 for the first row of the trip strips. The obtained effect was also confirmed by the results of thermal tests, i.e., the unevenness of heat transfer on the back and on the trough of the blade is observed at the first row of the trip strips, which amounts 8–12%. This unevenness has a fading character; at the second row of the trip strips, it amounts to 3–7%, and it is almost absent at the third row. At the area of vortex matrix, the intensity of heat exchange on the blade back is higher as compared to the trough, which is explained by the different height of the matrix ribs on its opposite sides. The design changes in the nozzle blade of basic modification made it possible to increase the intensity of heat exchange by 20–50% in the area of the vortex matrix and by 15–30% on the section of inclined intermittent trip strips. As a result of research, new criteria dependences for the complicated systems of heat exchange intensification were obtained. The design of nozzle blades can be used when developing the promising high-temperature gas turbines.     

土工格网处理桥头跳车机理的有限元分析

通过非线性有限元计算分析，探讨了采用土工格网处理头跳车的机理。结果表明，利用在台背锚固的土工格网张拉作用，可分层阻止填料顺台背的沉降；利用土工格网与填料之间良好的界面摩擦作用，改善土体内部的受力状态，提高土体的抵抗变形的能力。并与现场检测资料对比，证明了这一方法的有效性。     

Experience gained with development of the instrumentation and control system for the PGU-410 power unit at the Krasnodar cogeneration station on the basis of the tornado-n distributed control system

The development of the instrumentation and control system for the PGU-410 power unit at the Krasnodar cogeneration station is discussed. Problems encountered in designing the process control system of a complex facility are considered, in particular, the need to integrate local control systems. Special attention is paid to the importance of setting up a united control area at such facilities.