水力喷射压裂中环空水力封隔全尺寸实验

多级水力喷射压裂技术依靠水力封隔实现层段间隔离。通过地面全尺寸实验,提出从环空压力变化的角度评估水力封隔效率。实验中对喷射速度、围压、喷嘴直径和射孔入口直径以及环空注液对水力封隔效率的影响进行测试。实验结果表明:射流速度和围压是影响环空压力降低的两个主要因素,环空压力降低的幅度与射流速度呈线性增长关系,与围压呈指数递减关系;水力封隔效率与射流动能和孔道入口直径的比值成正比,可通过增大喷嘴直径和减小孔道入口直径的方法提高水力封隔能力;环空注液降低水力封隔效率。     

尾矿库安全监督管理体系建设的探索

随着国内工业建设的不断发展,矿产资源成为了当前规划建设体系中的一项重要举措。尾矿库是整个矿山工程非常重要的基础设施,是一个具有较高势能、能够引发泥石流的巨大安全隐患。所以加强尾矿库安全监管,排除尾矿库存在的各类安全隐患,对预防重大安全事故的发生以及保证矿区周围人们生命财产安全具有非常重要的实际意义。该文从尾矿库安全监管体系建设的现状与重要意义的角度入手,提出相应的解决措施,对尾矿库安全监管体系建设提进行了理论研讨。     

超磁致伸缩驱动微泵的磁场优化分析与实验验证

为使超磁致伸缩驱动微泵中超磁致伸缩材料(GMM)棒获得最佳的磁致伸缩性能,在ANSYS Maxwell软件中建立双线圈式驱动磁场、外线圈内永磁体式驱动磁场、内线圈外永磁体式驱动磁场模型,进行仿真分析,得到三种情况下微泵轴线上平均磁场强度和磁场均匀度,并通过试验验证优选结构的磁场强度和均匀度。结果表明:外线圈长度L_(q1)=104 mm,厚度d_(q1)=12.5 mm;内线圈长度L_(q2)=104 mm,厚度d_(q2)=12.5 mm的双线圈式驱动磁场相对于外线圈内永磁体式和内线圈外永磁体式平均磁场强度提高了117%和8.6%,磁场均匀度下降4%。试验结果与仿真结果基本吻合,验证了仿真模型的正确性。     

北京东灵山两种温带森林根际和非根际土壤酶活性、温度敏感性及矢量特征的季节动态

以北京东灵山两种主要植被类型——白桦(Betula platyphylla)林和辽东栎(Quercus wutaishanica)林土壤为研究对象, 于2017年春季(5 月)、夏季(7 月)、秋季(9 月)和冬季(12 月)分别采集根际与非根际土壤, 测定土壤理化性质、微生物生物量、植物根叶功能性状、3种水解酶(BG, NAG 和 AP)及两种氧化酶(POX和PER)的活性及其温度敏感性和矢量特征。结果表明, 白桦林和辽东栎林土壤胞外酶活性、温度敏感性和矢量角度均存在显著的季节变化趋势, 且水解酶活性及温度敏感性的变化趋势与氧化酶相反; 根际土壤与非根际土壤中胞外酶活性、温度敏感性及矢量特征存在差异, 但季节变化趋势相同。温度是土壤胞外酶活性温度敏感性及矢量特征季节动态的重要驱动因素, 土壤 pH、土壤养分含量、植物叶片养分含量及细根生物量、细根密度对土壤胞外酶活性、温度敏感性及矢量特征有显著影响。     

Reduced K-best sphere decoding algorithm based on minimum route distance and noise variance

This paper focuses on reducing the complexity of K-best sphere decoding （SD） algorithm for the detection of uncoded multi-ple input multiple output （MIMO） systems. The proposed algorithm utilizes the threshold-pruning method to cut nodes with partial Euclidean distances （PEDs） larger than the threshold. Both the known noise value and the unknown noise value are considered to generate the threshold, which is the sum of the two values. The known noise value is the smal est PED of signals in the detected layers. The unknown noise value is generated by the noise power, the quality of service （QoS） and the signal-to-noise ratio （SNR） bound. Simulation results show that by considering both two noise values, the proposed algorithm makes an efficient reduction while the performance drops little.     

Opportunistic spectrum sharing in software defined wireless network

Over the past few decades, the world has witnessed a rapid growth in mobile and wireless networks（MWNs） which significantly change human life. However, proliferating mobile demands lead to several intractable challenges that MWN has to face. Software-defined network is expected as a promising way for future network and has captured growing attention. Network virtualization is an essential feature in software-defined wireless network（SDWN）, and it brings two new entities, physical networks and virtual networks. Accordingly, efficiently assigning spectrum resource to virtual networks is one of the fundamental problems in SDWN. Directly orienting towards the spectrum resource allocation problem, firstly, the fluctuation features of virtual network requirements in SDWN are researched, and the opportunistic spectrum sharing method is introduced to SDWN. Then, the problem is proved as NP-hardness. After that, a dynamic programming and graph theory based spectrum sharing algorithm is proposed.Simulations demonstrate that the opportunistic spectrum sharing method conspicuously improves the system performance up to around 20%–30% in SDWN, and the proposed algorithm achieves more efficient performance.     

拟常全纯截面曲率空间中的全实极小子流形

用活动标架法研究拟常全纯截面曲率空间中的全实极小子流形,得到了关于第二基本形式模长‖B‖的Smions型积分不等式.     

Microelectronics-embedded channel bridging and signal regeneration of injured spinal cords

Due to the difficulty in spinal cord regeneration with biological methods, the microelectronic neural bridge, a new concept based on microelectronic technology, is presented. The microelectronic system has been realized in the forms of hybrid and integrated circuits. The integrated circuits for neural signal detection, stimulation, and regeneration are realized in a CMOS process. In animal experiments with 100 toads, 48 rats, and 3 rabbits, nerve signals have been successfully detected from spinal cords and sciatic nerves, and functional electrical stimulation has been carried out for spinal cords and sciatic nerves. When the microelectronic system is bridged between the controlling and stimulated nerve, the relevant motion of legs and nerve signal waveforms, which are stimulated by the evoked or spontaneous nerve signal through such a system, have been observed. Therefore, the feasibility of the presented method was demonstrated.     

考虑热解反应的阴燃渐近分析

用渐近分析法对一维稳态逆流阴燃进行了分析，模型中将填充床沿气体流动方向分成三个区，预热区、氧化降解区和热解反应区，分析表明，阴燃峰值温度和阴燃传播速度主要由降解来决定，崦氧化降解和热解反应同时决定热解区的结构，推导了活性物全部转换情况下的温度分布，气固质量分布表达式     

基于GIS方法的公路客运枢纽选址分析

城市公路客运枢纽的科学选址已成为城市总体规划和交通规划中不容忽视的重要环节，基于GIS分析方法，在考虑选址规划区域内存在地理阻断和路网运输服务水平的情况下，对一般的连续型选址模型进行修正，得到非连续型的阻抗函数，并通过成本费用最小化模拟分析客运枢纽的最优选址。