AFRP筋混凝土粘结强度和锚固长度的试验研究

通过对27个拉拔试件和16个梁式试件的试验,探讨AFRP筋与混凝土的粘结滑移关系、粘结强度,并且综合分析其他文献的结果,提出简化的局部粘结滑移本构关系和拔出破坏模式下锚固长度的计算公式。     

土钉支护结构中土钉长度的设计研究

土钉支护结构由于其诸多优点在深基坑中得到广泛应用,但是土钉长度布置问题一直是一个热点问题。本文研究了土钉长度的布置方式,结合工程实践,基于内部整体稳定性安全系数最小值的限制原则分析了土钉钻孔直径、水平倾角以及土钉间距等设计参数对土钉长度的影响,最后分析了不同土钉长度布置方式对安全系数的影响,所得结论可供工程技术人员参考。     

Completion and stimulation trends in North American unconventional plays and resulting impact on well productivity

过去十年,非常规油气勘探开发在全球范围内大幅扩张。水平钻井和多级水力压裂技术也在不断地发展和创新,使得超长水平井成为可能。同时,因为压裂强度不断增加,作业者可以最大限度地提高储层接触面积和对储层的改造体积 （SRV）。然而,完井优化方面的挑战仍然存在,作业者持续不断地尝试和试验各种完井与增产参数组合,以确保非常规油气藏开发的经济可行性。优选最佳的完井与增产参数组合是一项非常关键的任务,应结合油气田的具体储层特征进行优化。本文总结了2014—2020年间北美9个主要非常规油气藏的压裂增产趋势,包括Marcellus, Haynesville, Barnett, Utica, Bone Spring, Bakken, Wolfcamp Midland, Eagle Ford, Scoop/Stack。分析了各油气田几个关键的完井和增产参数的整体趋势,同时还评估了单个参数（如水平段压裂长度、支撑剂强度、段间距等）对井产能的影响。然后对比分析相应的初始井产量（90 天平均初始产量）,评估各个参数对产能的影响,从而确定每个完井参数的最佳范围,以实现产能最优化。     

检定S型短型热电偶的4种不同冷端补偿方法之比较

检定长度在200～700 mm范围内的S型热电偶时,由于参考端温度大都处于室温或者波动的温场之中,需要将参考端温度恒定在0℃或采取修正、补偿等措施进行修正。现采取检定中最常用的4种不同的冷端补偿方法检定同一支S型短型热电偶,对结果进行比较分析,得到这4种不同的冷端补偿方法的优劣性及其准确度排序。结果表明,将参考端应用达到一等标准热电偶准确度水平的同极性热电偶丝延伸至参考端恒温器方法能获得较为理想的补偿效果。     

High‐dose cefazolin on consecutive hemodialysis in anuric patients with Staphylococcal bacteremia

Methicillin‐sensitive Staphylococcus aureus (MSSA) bacteremia is a leading cause of infection in hemodialysis (HD) patients. Cloxacillin, cefazolin, and vancomycin are the mainstay antimicrobials. Cloxacillin administration leads to frequent drug dosing, longer length of stay (LOS), and higher cost, while resistance and poorer outcomes are associated with vancomycin use. Dosing cefazolin during HD allows for prolonged blood therapeutic levels. We assessed the outcomes and safety of a strategy of treating MSSA bacteremia with 2–3 g cefazolin on HD only. All HD patients with MSSA bacteremia admitted in June–December 2009 at our center and receiving this regime were compared with historical controls who received cloxacillin. Demographic characteristics and outcome measures like mortality, LOS, cost, recrudescence, and adverse drug reactions were assessed. Of 27 consecutive episodes reviewed, 14 and 13 patients received cefazolin and cloxacillin, respectively. Baseline demographics were comparable between the 2 treatment groups. More than one‐third of the bacteremia was related to tunneled catheter infection. The 30‐day mortality of cloxacillin‐ and cefazolin‐treated patients was 15% and 7%, respectively (P=0.14). Two of the 11 survivors treated with cloxacillin (18%) had recrudescent bacteremia while none was observed in cefazolin‐treated survivors. Cefazolin was associated with shorter LOS (10 vs. 20 days, P<0.05) and lower cost (US$8262.00 vs. US$15,367.00, P<0.05). Cefazolin use resulted in 3 idiosyncratic adverse drug reactions. Cefazolin dosed on each HD in MSSA bacteremia leads to earlier discharge and less cost. Larger prospective studies are, however, warranted to fully assess its safety and efficacy.     

One-dimensional V-Scope analysis of habituation to simulated cross-country skiing

Abstract

Responses to simulated cross-country skiing were measured using the V-Scope, a new telemetric ultrasound motion monitor. Ten young male adults performed a total of 45 minutes of distributed practice on a Nordic-Track^R ski simulator. Over a period of three 15-minute sessions cadence and velocity were unchanged. Step and stride lengths decreased significantly (p < 0-05) after the first 15-minute session and then remained unchanged. There were no left-right limb differences across all sessions indicating a normal gait. Response variability in velocity, step lengths and stride length was dramatically reduced after the first exposure period. This study demonstrates that the V-Scope system is a useful motion analysing device and, on the basis of the data presented in this preliminary investigation, at least two 15-minute habituation sessions are required for initial habituation to simulated cross-country skiing.     

GW4型隔离开关安装调试的一个典型问题分析

隔离开关在电力系统中有着至关重要的作用,其性能的好坏直接关系到整个系统能否安全稳定运行。在就GW4型隔离开关的两侧导电杆长度对隔离开关性能的影响进行了分析之后,提出了相应的安装、调试注意事项。     

基于改进SIFT特征提取的自主移动机器人环境识别方法研究

为了提高机器人在环境识别中的实时性和准确性,在分析了SIFT描述算子性能及原理的基础上,对SIFT算法在计算描述算子阶段提出自适应修改步长的改进,以及在原先的匹配方法的基础上又加入二次反向匹配,既在一定程度上提高了实时性又对关键点的消除错配起到较好的效果。仿真结果也证明了其有效性。     

透镜焦距频谱分析的解调测量

根据频谱分析原理,利用具有自扫描能力的CCD光电器件及解调测量的方法测量频谱间距,从而测得透镜焦距。讨论了信号的处理方法和测量误差。实验结果表明,误差小于0．2％。