Ground response and failure mechanism of gob-side entry by roof cutting with hard main roof

This study is the result of long-term efforts of the authors’team to assess ground response of gob-side entry by roof cutting(GSERC)with hard main roof,aiming at scientific control for GSERC deformation.A comprehensive field measurement program was conducted to determine entry deformation,roof fracture zone,and anchor bolt(cable)loading.The results indicate that GSERC deformation presents asymmetric characteristics.The maximum convergence near roof cutting side is 458 mm during the primary use process and 1120 mm during the secondary reuse process.The entry deformation is closely associated with the primary development stage,primary use stage,and secondary reuse stage.The key block movement of roof cutting structure,a complex stress environment,and a mismatch in the supporting design scheme are the failure mechanism of GSERC.A controlling ideology for mining states,including regional and stage divisions,was proposed.Both dynamic and permanent support schemes have been implemented in the field.Engineering practice results indicate that the new support scheme can efficiently ensure long-term entry safety and could be a reliable approach for other engineering practices.

Optimal Design of a Main Driving Mechanism for Servo Punch Press Based on Performance Atlases

The servomotor drive turret punch press is attracting more attentions and being developed more intensively due to the advantages of high speed,high accuracy,high flexibility,high productivity,low noise,cleaning and energy saving.To effectively improve the performance and lower the cost,it is necessary to develop new mechanisms and establish corresponding optimal design method with uniform performance indices.A new patented main driving mechanism and a new optimal design method are proposed.In the optimal design,the performance indices,i.e.,the local motion/force transmission indices ITI,OTI,good transmission workspace good transmission workspace(GTW) and the global transmission indices GTIs are defined.The non-dimensional normalization method is used to get all feasible solutions in dimensional synthesis.Thereafter,the performance atlases,which can present all possible design solutions,are depicted.As a result,the feasible solution of the mechanism with good motion/force transmission performance is obtained.And the solution can be flexibly adjusted by designer according to the practical design requirements.The proposed mechanism is original,and the presented design method provides a feasible solution to the optimal design of the main driving mechanism for servo punch press.

Damage and deterioration mechanism and curing technique of concrete structure in main coal cleaning plants

Concrete structures in main coal cleaning plants have been rebuilt and reinforced in the coal mines of the Shanghai Datun Energy Sources Co. Ltd., the first colliery of the Pingdingshan Coal Co. Ltd. and the Sanhejian mine of the Xuzhou Mining Group Co. Ltd. In these projects, the operating environment and reliability of concrete structures in the main plants of the three companies were investigated and the safety of the structures inspected. Qualitative and quantitative analyses were made on the special natural, technological and mechanical environments around the structures. On the basis of these analyses, we discuss the long-term, combined actions of the harsh natural (corrosive gases, liquids and solids) and mechanical environments on concrete structures and further investigated the damage and deteriorating mechanisms and curing techniques of concrete structures in the main coal cleaning plants. Our study can provide a theoretical basis for ensuring the reliability of concrete structures in main coal cleaning plants.

Preliminary estimation for the focal mechanisms of 1996 Lijiang main shock in Yunnan Province and studies of related problems

The mechanisms of the February 3, 1996 Lijiang main shock, Yunnan Province, are estimated by using the principle to inverse the mechanisms of two point sources simultaneously. The results are that the main shock of Lijiang consists of two large ruptures, the time difference and the distance between the two ruptures are about 12 s (by the inversion) and about 26 km respectively. An extensional normal with strike-slip fault in about the north-south direction was formed by the first rupture, the mechanism of the second rupture is to be further studied. The method to inverse mechanisms of two point sources at the same time and the results obtained by directly analyzing P waveform records of the main shock are introduced, some related problems are also discussed. The Wuding earthquakes of October, 1995 and the Lijiang earthquake are considered to be the manifestation of the same dynamic process at different temporal and spatial points and the occurrence order of the two earthquakes is related to the direction of dynamics transmission.

Analysis of main roof breaking form and its mechanism during first weightingin longwall face

By field observation and simulating test in shallow seam longwall mining, the asymmetry breaking of main roof is discovered during the first weighting. Based on simulating model test and theoretical analysis, the mechanism of main roof first breaking is revealed, and the asymmetry breaking parameter is determined at all.

Saline-Alkali(Mixed) Dust Storms and Their Main Generation Mechanism

The exposed surface of the dry salt lake basin contains a large number of extremely fine lightweight saline-alkali(mixed)dust and clay dust.It is extremely easy to dust and since saline-alkali lake is low-lying and its temperature

Enrichment Mechanism and Prospects of Deep Oil and Gas

With the deepening of oil and gas exploration,the importance of depth is increasingly highlighted.The risk of preservation of storage space in deep reservoirs is greater than that in shallow and medium layers.Deep layers mean older strata,more complex structural evolution and more complex hydrocarbon accumulation processes,and even adjustment and transformation of oil and gas reservoirs.This paper systematically investigates the current status and research progress of deep oil and gas exploration around the world and looks forward to the future research focus of deep oil and gas.In the deep,especially the ultra-deep layers,carbonate reservoirs play a more important role than clastic rocks.Karst,fault-karst and dolomite reservoirs are the main types of deep and ultra-deep reservoirs.The common feature of most deep large and medium-sized oil and gas reservoirs is that they formed in the early with shallow depth.Fault activity and evolution of trap highs are the main ways to cause physical adjustment of oil and gas reservoirs.Crude oil cracking and thermochemical sulfate reduction(TSR)are the main chemical modification effects in the reservoir.Large-scale high-quality dolomite reservoirs is the main direction of deep oil and gas exploration.Accurate identification of oil and gas charging,adjustment and reformation processes is the key to understanding deep oil and gas distribution.High-precision detection technology and high-precision dating technology are an important guarantee for deep oil and gas research.

Mechanism of gas pressure action during the initial failure of coal containing gas and its application for an outburst inoculation

Faced with the continuous occurrence of coal and gas outburst(hereinafter referred to as“outburst”)disasters,as a main controlling factor in the evolution process of an outburst,for gas pressure,it is still unclear about the phased characteristics of the coupling process with in situ stress,which induce coal damage and instability.Therefore,in the work based on the mining stress paths induced by typical outburst accidents,the gradual and sudden change of three-dimensional stress is taken as the background for the mechanical reconstruction of the disaster process.Then the true triaxial physical experiments are conducted on the damage and instability of coal containing gas under multiple stress paths.Finally,the response characterization between coal damage and gas pressure has been clarified,revealing the mechanism of action of gas pressure during the initial failure of coals.And the main controlling mechanism during the outburst process is elucidated in the coupling process of in situ stress with gas pressure.The results show that during the process of stress loading and unloading,the original gas pressure enters the processes of strengthening and weakening the action ability successively.And the strengthening effect continues to the period of large-scale destruction of coals.The mechanical process of gas pressure during the initial failure of coals can be divided into three stages:the enhancement of strengthening action ability,the decrease of strengthening action ability,and the weakening action ability.The entire process is implemented by changing the dominant action of in situ stress into the dominant action of gas pressure.The failure strength of coals is not only affected by its original mechanical strength,but also by the stress loading and unloading paths,showing a particularly significant effect.Three stages can be divided during outburst inoculation process.That is,firstly,the coals suffer from initial damage through the dominant action of in situ stress with synergy of gas pressure;secondly,the coals with spallation of structural division are generated through the dominant action of gas pressure with synergy of in situ stress,accompanied by further fragmentation;and finally,the fractured coals suffer from fragmentation and pulverization with the gas pressure action.Accordingly,the final broken coals are ejected out with the gas action,initiating an outburst.The research results can provide a new perspective for deepening the understanding of coal and gas outburst mechanism,laying a theoretical foundation for the innovation of outburst prevention and control technologies.

Research Progress of Action Mechanism of Mongolian Medicine Hatageqi-7 in the Treatment of Recurrent Aphthous Ulcer

Based on Mongolian medical theory and modern pharmacology,literature on the main components and action mechanism of Hatageqi-7 in the treatment of recurrent aphthous ulcer is collected,sorted and summarized.The research hopes to provide certain basis for its clinical efficacy from theory.

Adaptive Clutch Engaging Process Control for Automatic Mechanical Transmission

Based on detail analysis of clutch engaging process control targets and adaptive demands, a control strategy which is based on speed signal, different from that of based on main clutch displacement signal, is put forward. It considers both jerk and slipping work which are the most commonly used quality evaluating indexes of vehicle starting phase. The adaptive control system and its reference model are discussed profoundly. Taking the adaptability to different starting gears and different road conditions as examples, some proving field test records are shown to illustrate the main clutch adaptive control strategy at starting phase. Proving field test gives acceptable results.

Fracture mechanics model of fully mechanized top coal caving of shallow coal seams and its application

Based on break characteristics of roofs in fully mechanized top-coal mining of thick shallow coal seams, a fracture mechanics model was built, and the criterion of crack propagation in the main roof was derived using the fracture mechanics theory. The relationships between the fracture length of the roof and the working resistance of the supports were discovered, and the correlations between the load on the overlying strata and the ratio of the crack's length to the thickness of the roof were obtained. Using a working face of Jindi Coal Mine, Xing county Shanxi province as an example, the relationships between the fracture length of the roof and the working resistance of the supports were analysed in detail. The results give a design basis in hydraulic top coal caving supports, which could provide useful references in the practical application. On-site experiment proves that the periodic weighting step interval of the caving face is 15–16 m, which is basically consistent with the theoretical analysis results, and indicates that the mechanized caving hydraulic support is capable of meeting the support requirements in the mining of a super-thick but shallowly buried coal seam.

Ideas and Countermeasures for Perfecting Rural Public Product Supply from the Perspective of Main Beneficiaries

On the basis of defining the concept of rural public product supply, the weaknesses of the supply mechanism of rural public product are analyzed. The shortages of rural public product supply lead to the difficult ties in developing agriculture and rural economy; enriching farmers and narrowing the urban and rural income gap. Problems in rural public product supply are further analyzed. Firstly, the national finance used in agriculture is low. Secondly, farmers are not separated from decision system and the beneficiaries separate from the decision-makers. Thirdly, farmers are not fully treated as civilians. Fourthly, rural areas lack the selection and supervision mechanism of public product. The ideas and countermeasures on perfecting rural public product are put forward from the perspective of main beneficiaries. The supply of rural public product should take intensifying the self development capability of farmers as core; farmers should actively participate in the making the rural public product decision and fight for their right to say. Farmers should unit together through organizations to improve the organizational level. Farmers should actively participate in trainings on them and try to get the updated information from the local government. The village collective should protect the supply of rural public product.

Study on Varying Metallic Properties of Straight and Elbow Pipes of Main Steam Piping after Long-Time Service

The mechanic properties, lasting strength and microstructural properties of straight and elbow pipesof 12CrMo, 10CrMo910 and 12CrlMoV low alloy steel main steam piping system after long-time service weretested and studied. The testing results showed that, for straight and elbow pipes of mainsteam piping under theconditions of high temperature and high pressure, the numerical operating performance indexes of their metalchanged with little difference, generally both within 5%, and the Values of elbow were higher than those ofstraight pipes. These phenomena proved that the aging processes of pipe metal at different positions are thesame. And the cause for higher numerical performance indexes of elbow and higher failure rate at elbow posi-tion during operation of steam pipes were investigated.

健全我国粮食主产区利益补偿机制的新思路

粮食安全关乎国运民生,政府在战略上高度重视主产区利益补偿问题。当前,我国粮食产业面临产销区粮食供需矛盾加剧、经济发展差距加大、种粮收益不稳、主产区资源和环境压力激增等诸多压力与挑战,健全粮食主产区利益补偿机制、创新补偿思路是我国保障粮食安全亟待解决的现实难题。因此,在进一步拓展了粮食主产区利益补偿的理论基础上,提出利益补偿的新思路,要以公平、协调和可持续发展实现各区域的共同富裕为导向,形成多维度补偿机制。在纵向上,完善以政府为主导的利益补偿机制,提高补偿资金使用效能,在横向上,制定各区域责任分担机制,积极探索新型产销区协作关系,建立产销区横向利益补偿机制。此外,还要综合考虑主产区发展的显性和隐性损失,通过做好用地文章、提高产业核心竞争力、建立粮食生态补偿机制等途径弥补主产区经济发展的机会成本和粮食生产的资源消耗。

以糖厂为主体的甘蔗机收推进模式

近年来,我国甘蔗种植面积逐年减少,切段式甘蔗联合收获机保有量大幅增加,机收率却多年低位徘徊。针对这一问题,本文从方法论视角阐明当前甘蔗产业生产关系与新质生产力之间的矛盾,是机收推进缓慢的主要原因。提出以提高甘蔗产业的竞争力和促进产业可持续发展为目标,调整甘蔗产业当前生产关系,将当前生产关系中的各方组成机收推进联合体,构建以糖厂为主体的机收推进模式。该模式以免费或低价机收为杠杆,糖厂组织、协调、管理甘蔗机械化生产,实现了糖厂有稳定优质蔗源、机收组织效益稳定、蔗农获得免费(或低价)砍收甘蔗,达到多方共赢,有利于稳定甘蔗种植面积和甘蔗产业可持续发展。以该模式为抓手,建立试点并推广应用,在当前条件下,有望打破目前机收推进缓慢僵局,实现甘蔗机收快速推进。

鲜烟叶主脉力学特性试验研究

为研究鲜烟叶在机械手有序抓取过程中的破碎机理,以寸三皮黄烟品种为研究对象,利用万能试验机对新鲜烟叶主脉进行径向、侧向的压缩和剪切力学试验,得到不同作用位置的载荷-位移曲线,并利用Origin软件拟合烟叶主脉最大破碎力和剪切力的离散点变化规律曲线。结果表明,烟叶主脉径向和侧向压缩的最大破碎力均值为75.25 N,抗压强度均值为1.175 MPa,压缩弹性模量均值为5.79 MPa;径向和侧向最大剪切力均值为23.04 N,剪切强度均值为0.295 MPa,剪切模量均值为0.56 MPa。对烟株中部叶和下部叶的压缩和剪切力学特性进行比较,发现中部叶破碎和剪切需要施加更大的力。为机械手有序抓取烟叶提供理论基础和设计依据。

斯坦福大学科技成果高效转化的运行机制研究

推动大学科技成果走出实验室,将科技成果与经济发展紧密结合,使其转化为社会发展的推动力,是提升国家创新能力和竞争力的关键所在。斯坦福大学作为美国高校开展科技成果转化的先驱和当代美国大学技术转移标准模式的首创者,其成熟、专业且高效的科技成果转化机制不仅成为行业的典范,也为我国大学科技成果转化提供了参考与借鉴。

高校青年教师师德师风建设长效机制构建研究

新时期下,高校青年教师师德师风建设已经成为我国社会主义特色精神文明建设的重要组成部分之一。青年教师是我国高校的中坚力量,为建立专业化、素质化的青年教师团队,因此需要加强高校青年教师师德师风建设。为加快我国教育事业的发展进程,我国高校都在重视青年师德师风建设。该文分析当前高校青年教师师德师风建设过程中的主要困境,并进一步对构建高校青年教师师德师风建设长效机制提出一些可行性建议,尤其是对奖惩机制措施进行细化,为深入进行青年教师师德师风建设研究奠定理论基础。

九蒸九制槐角炮制过程主要成分、物性参数及颜色的相关性分析

目的研究九蒸九制槐角炮制过程中主要成分含量、物性参数、颜色的相关性。方法采用高效液相色谱法(HPLC)同时测定槐角苷、染料木苷、芦丁和5-羟甲基糠醛的含量,紫外分光光度法测定多糖的含量;通过测定物性参数和颜色指标(L*、a*、b*),结合系统聚类分析(HCA)、主成分分析(PCA)和偏最小二乘法(PLS)研究主要成分、物性参数及颜色的相关性;采用基于指标相关性的指标权重确定(CRITIC)法对槐角九蒸九制过程的影响进行综合评价。结果含量测定及色度测量方法准确可靠,精密度、稳定性、重复性试验均良好。HCA和PCA结果均表明,槐角饮片炮制过程中一蒸一制至四蒸四制聚为一类,五蒸五制至九蒸九制聚为一类。PLS相关性分析表明,多糖、芦丁的含量与物性参数、颜色均呈显著性相关;吸水膨胀度、相对密度与颜色均呈显著性相关。综合评价显示九蒸九制槐角炮制品最佳。结论九蒸九制槐角炮制过程中主要成分含量、物性参数、颜色的总体变化具有一定规律性,将其内在成分含量与颜色、物性参数结合为揭示槐角九蒸九制炮制机理提供了依据。

基于工程经济性的公路悬索桥主缆最优垂跨比研究

为寻求工程经济性最优的公路悬索桥主缆垂跨比,以我国近年多座采用混凝土桥塔的单跨公路悬索桥为背景,建立主缆、锚碇、桥塔基础工程量的直接函数模型和桥塔塔身工程量的非线性函数拟合模型,对跨度750~2250 m、单层车道数4~8及双层车道数6+4、垂跨比1/14~1/6共952种布置形式的悬索桥进行大范围关于主缆垂跨比的工程经济性研究,并以2座实桥为算例分析主缆垂跨比对悬索桥静、动力性能及抗风性能的影响。结果表明:主缆垂跨比对悬索桥工程经济性影响显著;悬索桥主缆最优垂跨比与跨度相关,而车道数、加劲梁荷载集度的影响相对较小,涉水和不涉水的差异也不显著;基于工程经济性考虑,跨度750~2250 m的悬索桥主缆最优垂跨比为1/6.5~1/8.5,比经验值增大较多。2座实桥算例分析表明随着垂跨比增加,加劲梁挠度和活载应力有所增加,抗风性能略有提升,建议方案设计阶段加大垂跨比研究范围、对工程经济性和桥梁力学性能进行综合比选。