DK-1型电空制动机在空气位增设断钩保护的电路改进方案

DK-1型电空制动机具有准、快、轻、静及便于检修等优点,并设有多重性安全措施,因此,深受运用、检修部门的喜爱。但该制动机有一严重的缺陷,即在空气位故障运行时,因电空控制器无电,在列车断钩时中立电空阀也无电,故不能切除列车管的供风源;若列车处于牵引工况,也不能自动切除机车的动力源。据有关资料介绍:从列车管直接放风时,如手柄在运转位,没有断钩保护功能的列车经过8秒机车就开始缓解,45秒内前部车辆共缓解8辆。同时。

对DK-1型电空制动机在空气位操纵产生自动缓解现象的处理意见

DK-1型电空制动机由于设计的原因,在空气位操纵时,列车施行常用制动后,容易产生自动缓解(俗称偷风),给安全行车将带来隐患,重者将造成“停不住”的危险事故。在空气位操作时,由于中立电空阀(253)无电,中继阀的遮断阀左侧无压力空气,该阀处于开放状态。在列车施行常用制动后,列车管如发生漏泄,中继阀供风阀口将开放,总风缸的压力空气将进入制动管,使制动管获得补风。由于我国多数车辆无阶段缓解装置,极易使车辆三通阀动作缓解。铁路技术管理规程第235条中规定,牵引列车时制动管压力漏泄每分钟不得超过0.2kgf/cm^2。这样,在长大坡道上。

DK-1型制动机空气位的缺陷及改进建议

分析DK－1型制动机空气位操作失效的原因，对原设计电路提出两种改造方案。

四川省环境空气质量监测点位存在问题及其优化

由于城市的发展规划,现有环境空气质量监测点位存在覆盖不全等问题,为客观准确反映城区环境空气质量,开展点位优化确有必要。调研四川省各市(州)点位具体情况,按照《环境空气质量监测点位布设技术规范(试行)》(HJ664-2013)要求,结合我省实际情况,探索三种点位优化方案:一是各建城区内至少有1个评价点,拟增加28个国控城市评价点;二是新增10%的评价点,拟增加10个国控城市评价点;三是调整清洁点,点位总数量未达到规范最低要求的未达标城市建成区内清洁对照点变更为城市评价点,撤销已达标城市清洁对照点,为“十四五”开展点位优化工作提供参考。

SS4改型机车DK-1型电空制动机的改进

装用DK-1型电空制动机的SS4改型机车在正常使用的电空位故障后,须转空气位操作维持运行,此时,会出现一系列的安全隐患,针对此类安全隐患,对制动机空气位电路进行改进,阐述了改进后的电路控制原理,并说明了改进后空气位操纵时的注意事项。

口罩过滤效率检测用颗粒物粒径的换算和标准比对

为理清口罩过滤效率检测用颗粒物粒径的相关科学概念,介绍了GB 2626—2006《呼吸防护用品自吸过滤式防颗粒物呼吸器》中所用颗粒物粒径及粒径分布的基本概念和描述方法。在回顾呼吸性粉尘和空气动力学质量中位径(MMAD)概念的基础上,重点介绍了计数中位径(CMD)换算为MMAD的方法,通过计算证明GB 2626—2006中过滤效率测试用颗粒物的MMAD为0.3μm,该粒径为最具有穿透性的颗粒物粒径。应用该换算方法,探讨了AQ 1114—2014《煤矿用自吸过滤式防尘口罩》中以MMAD大于7μm粗粉尘颗粒物测试过滤效率的局限性,并采用MMAD为0.3μm的颗粒物评估典型口罩材料的过滤效率,为正确评价国内外防颗粒物口罩标准提供专业指导。

基于空气稳定金属配位活化的n型掺杂技术及其进展

n型掺杂技术是提高电子注入性能、改善载流子平衡的有效方法,被广泛运用于有机电子学领域.近年来,基于空气稳定金属配位活化的n型掺杂(coordination-activated n-doping,CAN)技术受到了广泛关注.相对于传统n型掺杂技术,CAN具有对空气稳定、适用于多种电极、可抑制金属迁移、无副产物、工艺简单等优势,有望解决当前有机发光二极管(OLED)显示依赖易燃活泼金属实现电子注入的缺点.本文回顾了OLED中的n型掺杂体系研究进展,着重介绍了CAN策略及其机理,并对CAN的最新进展及其在OLED中的应用进行了专题介绍.最后,我们对CAN尚存在的问题及未来的发展方向进行了总结和展望.

Location of anemometer along Lanzhou-Xinjiang railway

Using structured mesh to discretize the calculation region, the wind velocity and pressure distribution in front of the wind barrier under different embankment heights are investigated based on the Detached Eddy Simulation(DES) with standard SpalartAllmaras(SA) model. The Reynolds number is 4.0×105 in this calculation. The region is three-dimensional. Since the wind barrier and trains are almost invariable cross-sections, only 25 m along the track is modeled. The height of embankment ranges from 1 m to 5 m and the wind barrier is 3 m high. The results show that the wind speed changes obviously before the wind barrier on the horizontal plane, which is 4.5 m high above the track. The speed of wind reduces gradually while approaching the wind barrier. It reaches the minimum value at a distance about 5 m before the wind barrier, and increases dramatically afterwards. The speed of wind at this location is linear with the speed of far field. The train aerodynamic coefficients decrease sharply with the increment of the embankment height. And they take up the monotonicity. Meanwhile, when the height increases from 3 m to 5 m, they just change slightly. It is concluded that the optimum anemometer location is nearly 5 m in front of the wind barrier.

Sensitivity and effect of key operational parameters on performance of a dual-cylinder free-piston engine generator

The free-piston engine generator(FPEG)is regarded as the next generation of energy conversion system which may replace traditional engines in the future.The effect of key operational parameters like excess air ratio of input mixture and ignition position on the engine performance of a dual-cylinder FPEG was investigated,and their sensitivity was analyzed in this paper.The operating compression ratio of the system is susceptible to changes in excess air ratio and ignition position.At the same time,it decreases from 15.8 to 6.6 when excess air ratio increases from 0.85 to 1.15,but it increases from 6.1 to 13.3 as ignition position increases from 15 mm to 20 mm.The operating frequency and indicated power are more sensitive to changes in excess air ratio than ignition position.But it is the opposite for the indicated thermal efficiency and friction loss.Excess air ratio and ignition position have a quite similar influence on heat transfer.Therefore,from the perspective of system operation and performance,it is preferable to keep excess air coefficient slightly below 1.0.In contrast,when selecting ignition position,it is of great importance to comprehensively consider the risk of structural damage caused by the increase in the compression ratio and in-cylinder gas pressure.

AN AIR POLLUTION PREDICTION TECHNIQUE FOR URBAN DISTRICTS BASED ON MESO-SCALE NUMERICAL MODEL

Taking Shenzhen city as an example, the statistical and physical relationship between the density of pollutants and various atmospheric parameters are analyzed in detail, and a space-partitioned city air pollution potential prediction scheme is established based on it. The scheme considers quantitatively more than ten factors at the surface and planetary boundary layer (PBL), especially the effects of anisotropy of geographical environment, and treats wind direction as an independent impact factor. While the scheme treats the prediction equation respectively for different pollutants according to their differences in dilute properties, it considers as well the possible differences in dilute properties at different districts of the city under the same atmospheric condition, treating predictions respectively for different districts. Finally, the temporally and spatially high resolution predictions for the atmospheric factors are made with a high resolution numerical model, and further the space-partitioned and time-variational city pollution potential predictions are made. The scheme is objective and quantitative, and with clear physical meaning, so it is suitable to use in making high resolution air pollution predictions.

In-situ decoration of metallic Bi on BiOBr with exposed(110)facets and surface oxygen vacancy for enhanced solar light photocatalytic degradation of gaseous n-hexane

Photocatalytic degradation of gaseous pollutants on Bi-based semiconductors under solar lightirradiation has attracted significant attention.However,their application in gaseous straight-chainalkane purification is still rare.Here,a series of Bi/BiOBr composites were solvothermally synthe-sized and applied in solar-light-driven photocatalytic degradation of gaseous n-hexane.The charac-terization results revealed that both increasing number of functional groups of alcohol solvent(from methanol and ethylene glycol to glycerol)and solvothermal temperature(from 160 and 180to 200℃)facilitated the in-situ formation of metallic Bi nanospheres on BiOBr nanoplates withexposed(110)facets.Meanwhile,chemical bonding between Bi and BiOBr was observed on theseexposed facets that resulted in the formation of surface oxygen vacancy.Furthermore,the synergis-tic effect of optimum surface oxygen vacancy on exposed(110)facets led to a high visible light re-sponse,narrow band gap,great photocurrent,low recombination rate of the charge carriers,andstrong·O2-and h*formation,all of which resulted in the highest removal efficiency of 97.4%within120 min of 15 ppmv of n-hexane on Bi/BiOBr.Our findings efficiently broaden the application ofBi-based photocatalysis technology in the purification of gaseous straight-chain pollutants emittedby the petrochemical industry.

Air-Flow Distribution Efficiency of a Precision Drill Used in the Sowing of Different Graded Seeds

Uniform seed spacing is considered a fundamental factor in quality and yield for many crops and drill manufacturers continuously try to improve the accuracy in seed placement, according to the cultivation standard requirements. This paper reports the results of tests on the performances of a six row pneumatic precision drill in which the depression into each sowing unit is created by means of flexible pipes that do not start directly from the fan, as in most pneumatic drills, but from an air duct having the function of uniformly distributing the air flow along the working width. Field tests have been conducted, using three graded seeds, to evaluate the accuracy of the single seed metering system, according to ISO 7256/1 standard, and the uniformity of negative pressure, through the measurement of the distance between seeds in the furrow, under two speed conditions （5 and 8 km bl）.

Improved SMB speckle filtering of polarimetric SAR data with synergistic use of orientation angle compensation and spatial majority rule

The scattering-model-based(SMB)speckle filtering for polarimetric SAR(Pol SAR)data is reasonably effective in preserving dominant scattering mechanisms.However,the efficiency strongly depends on the accuracies of both the decomposition and classification of the scattering properties.In addition,a relatively weak speckle reduction particularly in distributed media was reported in the related literatures.In this work,an improved SMB filtering strategy is proposed considering the aforementioned deficiencies.First,the orientation angle compensation is incorporated into the SMB filtering process to remedy the overestimation of the volume scattering contribution in the Freeman-Durden decomposition.In addition,an algorithm to select the homogenous pixels is developed based on the spatial majority rule for adaptive speckle reduction.We demonstrate the superiority of the proposed methods in terms of scattering property preservation and speckle noise reduction using L-band Pol SAR data sets of San Francisco that were acquired by the NASA/JPL airborne SAR(AIRSAR)system.

Prediction of the position of coal particles in an air dense medium fluidized bed system

An air dense medium fluidized bed separator(ADMFBS) is used for dry beneficiation of coal using ultrafine magnetite particles as a pseudo-fluid medium. In this process, the coal particle gains additional weight due to coating on its surface and deposition at dead zone area by fine magnetite particles.Hence, the effective density of coal particle increases and the position of coal particle changes accordingly. In this work, an attempt was made to predict the position of coal particle in non-bubbling condition dense medium fluidized bed system. Coal particles of different shape such as cubical, rectangular prism,spherical and triangular prism with different projected area and density were used. The results show that the position of coal particle in air dense medium fluidized bed follows descending order with respect to the increase of density, projected area of coal particle and different shapes(i.e., triangular prism, cubical,rectangular prism and spherical). Empirical mathematical correlations were developed to predict the position of coal particle.

Doping effect of cations(Zr^(4+),Al^(3+),and Si^(4+)) on MnO_x/CeO_2 nano-rod catalyst for NH_3-SCR reaction at low temperature

Thermally stable Zr4+, Al3+, and Si4+ cations were incorporated into the lattice of CeO2 nano‐rods (i.e., CeO2‐NR) in order to improve the specific surface area. The undoped and Zr4+, Al3+, and Si4+ doped nano‐rods were used as supports to prepare MnOx/CeO2‐NR, MnOx/CZ‐NR, MnOx/CA‐NR, and MnOx/CS‐NR catalysts, respectively. The prepared supports and catalysts were comprehensively characterized by transmission electron microscopy (TEM), high‐resolution TEM, X‐ray diffraction, Raman and N2‐physisorption analyses, hydrogen temperature‐programmed reduction, ammonia temperature‐programmed desorption, in situ diffuse reflectance infrared Fourier‐transform spectroscopic analysis of the NH3 adsorption, and X‐ray photoelectron spectroscopy. Moreover, the catalytic performance and H2O+SO2 tolerance of these samples were evaluated through NH3‐selective catalytic reduction (NH3‐SCR) in the absence or presence of H2O and SO2. The obtained results show that the MnOx/CS‐NR catalyst exhibits the highest NOx conversion and the lowest N2O concentration, which result from the largest number of oxygen vacancies and acid sites, the highest Mn4+ content, and the lowest redox ability. The MnOx/CS‐NR catalyst also presents excellent resistance to H2O and SO2. All of these phenomena suggest that Si4+ is the optimal dopant for the MnOx/CeO2‐NR catalyst.

Stable Isotopes in Precipitation in Xilin River Basin,Northern China and Their Implications

Under the increasing pressure of water shortage and steppe degradation, information on the hydrological cycle in steppe region in Inner Mongolia, China is urgently needed. An intensive investigation of the temporal varia-tions of δD and δ^18O in precipitation was conducted in 2007-2008 in the Xilin River Basin, Inner Mongolia in the northern China. The 6D and δ^18O values for 54 precipitation samples range from ＋1.1%o to -34.7%0 and -3.0%0 to -269%0, respectively. This wide range indicates that stable isotopes in precipitation are primarily controlled by differ-ent condensation mechanisms as a function of air temperature and varying sources of vapor. The relationship between δD and δ^18O defined a well constrained line given by δD = 7.896180 ＋ 9.5, which is nearly identical to the Meteoric Water Line in the northern China. The temperature effect is clearly displayed in this area. The results of backward tra-jectory of each precipitation day show that the vapor of the precipitation in cold season （October to March） mainly originates from the west while the moisture source is more complicated in warm season （April to September）. A light precipitation amount effect existes at the precipitation event scale in this area. The vapor source of precipitation with higher d-excesses are mainly from the west wind or neighboring inland area and precipitation with lower d-excesses from a monsoon source from the southeastern China.

Effects of Ambient Conditions and Nozzle Design on the Velocity of Clustered Diesel Jets

The measurement of droplet velocities in Diesel sprays close to the nozzle is important because of the complexity of in-nozzle flow, spray break-up and evaporation. However, the measurement of droplet velocities in the dense region of Diesel sprays is very difficult or impossible by means of widely used laser diagnostic techniques, in particular under engine-like high-pressure and high-temperature conditions. The limitations of phase Doppler anemometry （PDA） and particle image velocimetry （PIV） prevent the application to the ultra-dense region of the spray. It was demonstrated that these problems can be greatly reduced by the laser flow tagging （LFT） technique. It was also demonstrated recently that LFT measurements can be conducted in clustered Diesel jets with improved spatial resolution and increased number of simultaneous measurements in the near-nozzle region. In the present work, the nozzle design, the temperature and pressure of the ambient air, and the fuel rail pressure are varied, in order to investigate the influence on the near-nozzle jet velocity and the underlying physical mechanisms.

Cleaning Technology of Operating Rooms in Hospitals

This paper is based on a literature review of foreign research regarding the relationship between： SSI （surgical-site infection） and operating room cleaning ventilation, the change of cleanroom technical factors of ventilation, and air conditioning in operating rooms. The differences between foreign codes and Chinese codes on cleaning and the air conditioning index of operating rooms are discussed. The historic background of the founding of the current Chinese clean operating room codes was analyzed. The author appealed to insiders for awareness and concentration on international medical research results involved in cleaning and air conditioning techniques of operating rooms. The current domestic codes should be modified based on the real situation of China. Therefore, the development of medical facilities can be fulfilled.

Multi-dimensional hierarchical CoS_(2)@MXene as trifunctional electrocatalysts for zinc-air batteries and overall water splitting

The demanding all-in-one electrocatalyst system for oxygen reduction reaction(ORR), oxygen evolution reaction(OER) and hydrogen evolution reaction(HER) in zinc-air batteries or water splitting requires elaborate material manufacturing, which is usually complicated and time-consuming.Efficient interface engineering between MXene and highly active electrocatalytic species(CoS_(2)) is, herein, achieved by an in situ hydrothermal growth and facile sulfurization process.The CoS_(2)@MXene electrocatalyst is composed by one-dimensional CoS_(2) nanowires and two-dimensional MXene nanosheets, which lead to a hierarchical structure(large specific surface area and abundant active sites), a spatial electron redistribution(high intrinsic activity), and high anchoring strength(superior performance stability). Therefore, the electrocatalyst achieves enhanced catalytic activity and longtime stability for ORR(a half-wave potential of 0.80 V), OER(an overpotential of 270 mV at 10 mA cm^(-2), i.e., η10= 270 mV)and HER(η10= 175 mV). Furthermore, the asymmetry water splitting system based on the CoS_(2)@MXene composites delivers a low overall voltage of 1.63 V at 10 mA cm^(-2). The solidstate zinc-air batteries using CoS_(2)@MXene as the air cathode display a small charge-discharge voltage gap(0.53 V at1 mA cm^(-2)) and superior stability(60 circles and 20-h continuous test). The energy interconversion between the chemical energy and electricity can be achieved by a self-powered system via integrating the water splitting system and quasisolid-state zinc-air batteries. Supported by in situ Raman analyses, the formation of cobalt oxyhydroxide species provides the active sites for water oxidation. This study paves apromising avenue for the design and application of multifunctional nanocatalysts.

The Monte-Carlo simulation on a scintillator neutron detector

A simulation of the properties of the shifting scintillator neutron detector using 6LiF/ZnS(Ag) scintillation screens is performed.The simulation results show that the light attenuation length of standard BC704 scintillator is about 0.65 mm.Its thermal neutron detection efficiency,gamma sensitivity and intrinsic spatial resolution can achieve around 50.0%,10 5and 0.18 mm(along X-axis) respectively.For the detector,air coupling position resolution is better than the silicone oil coupling.Some of the simulation results are compared with experimental results.They are in agreement.This work will be helpful for constructing neutron detector for high intensity powder diffractometer at Chinese spallation neutron source.