V型尾门在河工模型试验中的应用

尾门是河工模型中常见的装置,也是水位控制的关键设备之一.该文作者根据多年的经验,研制了一种新式尾门--V型尾门.该尾门具有调节精度高、稳定性好、操作方便等优点.并在多个模型中应用,取得了良好的控制效果.文章介绍了V型尾门的制作要点,并结合试验数据论述具体应用效果.     

水力模型尾水测控系统数学模型

尾水测控系统是非恒定流水力模型自动测控系统的重要组成部分．采用翻板尾门进行尾水调节，具有反应快、调节范围大等优点，是非恒定流水力模型控制尾水位一种常用的方法．采用加入非线性校正法，对翻板门尾水测控系统的性能指标和稳定性进行改善，取得良好效果．     

尾式卟啉铁轴向加合含氮配体的共振拉曼光谱的研究

测定了尾式卟啉[5-邻-(4-二甲胺基丁酰胺)苯基-10,15,20-三苯基卟啉](简记 meso-MDMBPTPPH_2)、尾式卟啉铁配合物及其轴向与咪唑、吡啶、三乙胺、二乙胺、乙胺、正丙胺、正丁胺含 N 配体加合物的共振拉曼光谱.详细指认了其振动谱带,考察了轴向配体的改变对 Fe—N 键拉曼伸缩振动的影响.实验结果表明:尾式卟啉尾端侧链的存在,阻碍了苯环的旋转,使苯环与卟啉环相互作用减弱,Raman 光谱产生分裂.1363 cm~(-1)强的振动谱带的出现,证实了尾式卟啉铁是高自旋状态.轴向配体对 Fe—N 伸缩振动谱带有较大的影响,其频率有:咪唑>有机胺>吡啶的规律,同时与轴向配位平衡常数之间存在着:v=8.9log K+338的关系.     

一种低速情况下无尾飞翼飞机航向控制方法

无尾飞翼飞机通常使用开裂式阻力方向舵或者嵌入式操纵面来解决其航向控制问题。开裂式阻力方向舵对飞机的航向控制机理与传统方向舵不同,其舵效随舵偏角的变化呈非线性特性,且在较大迎角时会产生操纵反效现象,诱发航向振荡,产生飞行事故。针对此问题,利用CFD方法分析了某小型无尾飞翼飞机开裂式阻力方向舵的操纵特性,提出一种基于迎角反馈的开裂式阻力方向舵预偏差动控制方法,并进行了非线性数值仿真和试飞验证。结果表明:该方法可以改善开裂式阻力方向舵的非线性特性,解决操纵反效问题,增强无尾飞翼飞机低速飞行时的航向控制性能。     

过程式语言中递归的消除

尾递归化是程序分析中的一个基本方法，通过对过程式语言中递归函数尾递归化几个特殊方法的比较分析，给出了一个较一般的方法。     

一种新型“尾式”卟啉的合成

根据不同性质的要求对卟啉环进行化学修饰是一个重要研究课题,对卟啉环的修饰一般是在卟啉环平面的一侧引入疏水障碍基因,由于其空间障碍作用和屏蔽作用,从而避免双分子不可逆氧化和质子进攻,使吸氧络合物趋于稳定。本文以α－溴代硬脂酸乙酯与不对称四苯基卟啉反应,合成了新的带有脂肪长链的拖尾卟啉,以期在模拟某些生物活性机理研究中成为较好的模型化合物。     

水轮机尾水管内的流动模拟

混流和轴流定浆式水轮机在部分负荷下运行时,尾水管中常出现较为强烈的振动。这种振动主要是由尾水管中的旋涡带所致。本文通过尾水管内流动的模拟,导出了由尾水涡带所引起的周期性振动的振动频率和脉动压力的计算公式。     

浅析中国传统之“门”的建筑形式与文化含蕴

门作为建筑元素之一,在中国古典建筑型制中有着重要的作用。一方面,门从依附于建筑的构件门发展成为独立的单体门,成为传统院落式建筑组群的空间组织核心;另一方面,门不仅具有实用功能、纪念功能,同时也表现出严格的等级制度,成为儒家礼制文化的表征符号。通过对门的功能、形式、象征性、纪念性以及门与建筑平面、立面的构成关系等进行分析,揭示其深厚的社会伦理及建筑美学内涵,并为建筑创作提供参考。     

关于重尾分布的一些探讨

讨论了由慢变化函数形式给出的重尾分布定义,与由指数阶矩形式给出的重尾分布定义是否一致.利用分析中的极限理论等方法,证明了重尾分布的这两种定义是一致的,并给出了重尾分布子族间的相互关系.     

导弹尾焰对其飞行性能的影响研究

基于压力隐式算子分裂（pressure implicit with splitting of operators, PISO）算法,通过求解Navier-Stokes方程,对不同尾部形状的弹体在M∞=1.2～10飞行条件下发动机内流场、尾焰及弹体绕流形成的干扰流场进行了一体化数值仿真,得出了马赫数、弹体表面压力等流场参数的分布.用TTM方法生成结构网格,采用标准k-ε两方程湍流模型.结果表明：尾部形状为直角时,M∞越大,尾焰膨胀与边界层分离越弱,尾焰诱导激波越靠近弹体尾部;尾部形状为环形时,尾焰对导弹飞行性能影响较小.计算结果与试验数据吻合,可为工程设计提供参考.     

济三煤矿沿空巷道矿压显现规律研究

针对济三煤矿综放工作面断层发育、坚硬顶板围岩地质条件,设计了综放面小煤柱沿空巷道锚杆(索)支护参数.巷道在施工过程中,采用顶板离层仪和钻孔窥视仪,较系统地观测研究了沿空掘巷矿压显现规律.研究结果表明:巷道顶板下沉量较小,锚固区内外岩层离层量小巷道掘进影响区范围为50m左右;巷道底臌较严重,巷道两帮移近明显,围岩收敛后巷道由矩形断面变形成为倒梯形断面;沿空巷道煤柱中节理裂隙十分发育,煤体压缩变形成为块状结构的塑性松散体.综放面回采期间巷道断面大小满足使用要求,说明了沿空巷道锚杆支护,能够经受住综放工作面采动影响,锚杆支护试验取得了成功.研究成果在综放面沿空掘巷中进行了推广应用.     

皮卡车外流场的数值模拟

采用CFD进行皮卡车的外流场模拟,得到了车身表面压力分布、尾流典型剖面流速值和尾流流场结构,数值模拟结果与风洞试验结果吻合较好。模拟结果表明,皮卡车尾涡存在于货箱上方和尾挡板后方两个区域。进行了皮卡车几种几何改型的CFD模拟,所得阻力系数变化与实车试验结果有相同的变化趋势,证实了尾挡板的减阻作用。由此得出CFD用于皮卡车外流场模拟,可获得较高的模拟精度。     

Identification methods for anomalous stress region in coal roadways based on microseismic information and numerical simulation

It is believed that the microseismicity induced by mining effect and gas gradient disturbance stress is a precursor to the essential characteristics of roadway unstability. In order to effectively identify and evaluate the stability of coal roadways in the process of mine development and extraction, a microseismic monitoring system was deployed for the study of the stress evolution process, damage degree and distribution characteristics in the tailgate and headgate. The mine under study is the 62113 outburst working face of Xin Zhuangzi coalmine in Huainan mining area. The whole process of microfractures initiation,extension, interaction and coalescence mechanisms during the progressive failure processes of the coal rock within the delineated and typical event clusters were investigated by means of a two dimensional realistic failure process analysis code(RFPA2D-Flow). The results show that the microseismic events gradually create different-sized event clusters. The microseismicity of the tailgate is significantly higher than that of the headgate. The study indicates that the greater anomalous stress region matches the area where microfractures continuously develop and finally connect to each other and form a fissure zone.Due to the mine layout and stress concentration, the ruptured area is mainly located on the left shoulder of the tailgate roof. The potential anomalous stress region of the coal roadway obtained by numerical simulation is relatively in good agreement with the trend of spatial macro evolution of coal rock microfractures captured by the microseismic monitoring system. The research results can provide important basis for understanding instability failure mechanism of deep roadway and microseismic activity law in complex geologic conditions, and it ultimately can be used to guide the selection and optimization of reinforcement and protection scheme.     

Bleeder entry evaluation using condition mapping and numerical modeling

One of the most common critical areas of longwall mining in terms of ground stability are the gateroad and bleeder entries. These critical entries provide much-needed safe access for miners and allow for adequate ventilation required for dilution of hazardous airborne contaminants and must remain open during mining of a multi-panel district. This paper is focused on the stability of the longwall entries subjected to a single abutment load such as bleeders, first tailgate, and last headgate. First tailgate and last headgate are also referred to as blind headgate and tailgate. A study of a longwall district through conditions mapping, support evaluations, and numerical modeling was conducted and evaluated by researchers from the National Institute for Occupational Safety and Health(NIOSH). The condition mapping and support evaluations were performed on entries that spanned the previous five years of mining and relied on a diverse selection of supports to maintain the functionality of the entry. Numerical modeling was also conducted to evaluate various support types with further investigation and comparison to the condition mapping.The study demonstrated the importance of the abutment load decay versus distance from the gob edge,the potential for a reduction in material handling related injuries, as well as optimal usage of secondary and standing support.     

Analysis of monitored ground support and rock mass response in a longwall tailgate entry

A comprehensive monitoring program was conducted to measure the rock mass displacements, support response, and stress changes at a longwall tailgate entry in West Virginia.Monitoring was initiated a few days after development of the gateroad entries and continued during passage of the longwall panels on both sides of the entry.Monitoring included overcore stress measurements of the initial stress within the rock mass, changes in cable bolt loading, standing support pressure, roof deformation, rib deformation,stress changes in the coal pillar, and changes in the full three-dimensional stress tensor within the rock mass at six locations around the monitoring site.During the passage of the first longwall, stress measurements in the rock and coal detected minor changes in loading while minor changes were detected in roof deformation.As a result of the relatively favorable stress and geological conditions, the support systems did not experience severe loading or rock deformation until the second panel approached within 10–15 m of the instrumented locations.After reaching the peak loading at about 50–75 mm of roof sag, the cable bolts started to unload, and load was transferred to the standing supports.The standing support system was able to maintain an adequate opening inby the shields to provide ventilation to the first crosscut inby the face, as designed.The results were used to calibrate modeled cable bolt response to field data, and to validate numerical modeling procedures that have been developed to evaluate entry support systems.It is concluded that the support system was more than adequate to control the roof of the tailgate up to the longwall face location.The monitoring results have provided valuable data for the development and validation of support design strategies for longwall tailgate entries.     

Deformation mechanism and stability control of roadway along a fault subjected to mining

It is difficult to maintain the roadway around a fault because of the fractured surroundings, complex stress environment, and large and intense deformation in the mining process. Based on a tailgate of panel S2205 in Tunliu colliery, in Shanxi province, China, we investigated the evolution of stress and displacement of rocks surrounding the roadway during the drivage and mining period using theoretical analysis, numerical simulation and field trial methods. We analyzed the deformation and failure mechanisms of the tailgate near a fault. The deformation of surrounding rock caused by unloading in the drivage period is large and asymmetric, the roadway convergence increases with activation of the fault and secondary fracture develops in the mining period. Therefore, we proposed a specific control technique of the roadway along a fault as follows: (1) High-strength yielding bolt not only supports the shallow rock to load-bearing structures, but also releases primary deformation energy by use of a pressure release device in order to achieve high resistance to the pressure retained; (2) Grouting of near-fault ribside after initial stabilization of the rock deformation is used to reinforce the broken rock, and to improve the integral load-bearing capacity of the roadway. The research results were successfully applied to a field trial.     

Development process for a higher capacity Propsetter~ system

As longwall tailgate support technologies continue to be developed and improved, strata worldwide has worked to design and manufacture a revised Propsetter to provide additional support capacity and enable applications at greater mine heights.The support is targeted for tailgate applications, however, it can also be utilized for roof support in various types of mining environments.This paper describes the design changes for enhancing the support capacity of the Propsetter to more closely align its performance with other support technologies currently being employed in longwall tailgates.Balancing changes to each design aspect of the Propsetter was key to successfully improving the roof support's load capacity while maintaining controlled deformation.Increasing the load capacity would allow a mine to improve support efficiency with a smaller, less intrusive support compared to support alternatives and reduce the cost per foot of supported entry.The target support capacity was 711–890 k N at 50 mm of deformation to more closely match the performance of competing tailgate supports such as the 610 mm-diameter CAN~.To achieve this goal, changes were made to all design aspects of the Propsetter: diameter, wedge cut depth and angle, pod size, and confinement rings.Test results from the NIOSH Mine Roof Simulator verified that these design changes were successful in increasing the capacity of the Propsetter to the 711–890 k N range at fifty mms of deformation.     

Optimization of gob ventilation boreholes design in longwall mining

Gob ventilation boreholes (GVBs) are widely used for degasification in U.S. longwall coal mines. Depending on geological conditions, 30–50% of methane can be recovered from longwall gob using GVBs. A NIOSH funded research at the Colorado School of Mines confirmed that GVBs can efficiently reduce methane at the face. However, GVBs can also draw some fresh air from the face and create explosive gas zones (EGZs). Explosive gas mixtures may be formed in gob areas due to the increased ingress of oxygen from GVBs. It is critical to identify the locations for GVBs for maximizing extraction of methane and minimizing hazards of explosion. This study analyzes the effect of operating parameters and design of GVB on methane extraction, EGZs formation, and face and tailgate methane concentrations. Methane extraction, formation of EGZs, and concentration of methane in working areas are significantly impacted by various factors. These factors include the distance of work face and tailgate from GVBs, diameter of GVBs, vacuum pressure of wellhead, GVB distance from the roof of the coal seam, and number of operating GVBs in a panel. Computational fluid dynamics (CFD) evaluations suggest optimal design and operating parameters of GVBs that can contribute to maximum benefits with minimum risks.     

高应力回采巷道围岩变形特征及协调支护技术研究

为了研究高应力条件下回采巷道围岩变形特征,以石板沟煤业18002工作面回风巷为研究对象,根据该巷道工程地质特点,采用FLAC3D数值模拟软件,分析高应力工作面回风巷的变形影响因素,提出高预应力高强锚杆与锚索协调支护的总体思路．分析可知,围岩变形较大是多重原因综合作用的结果;采用高预应力高强锚杆．锚索协调支护对高应力巷道围岩变形控制效果明显;工业性试验结果表明,该技术能有效控制巷道围岩变形,为矿井安全生产创造条件,并取得较好的效果．