Assessing cutter-rock interaction during TBM tunnelling in granite:Large-scale standing rotary cutting tests and 3D DEM simulations

The widespread utilisation of tunnel boring machines(TBMs)in underground construction engineering requires a detailed investigation of the cutter-rock interaction.In this paper,we conduct a series of largescale standing rotary cutting tests on granite in conjunction with high-fidelity numerical simulations based on a particle-type discrete element method(DEM)to explore the effects of key cutting parameters on the TBM cutter performance and the distribution of cutter-rock contact stresses.The assessment results of cutter performance obtained from the cutting tests and numerical simulations reveal similar dependencies on the key cutting parameters.More specifically,the normal and rolling forces exhibit a positive correlation with penetration but are slightly influenced by the cutting radius.In contrast,the side force decreases as the cutting radius increases.Additionally,the side force shows a positive relationship with the penetration for smaller cutting radii but tends to become negative as the cutting radius increases.The cutter's relative effectiveness in rock breaking is significantly impacted by the penetration but shows little dependency on the cutting radius.Consequently,an optimal penetration is identified,leading to a low boreability index and specific energy.A combined Hertz-Weibull function is developed to fit the cutter-rock contact stress distribution obtained in DEM simulations,whereby an improved CSM(Colorado School of Mines)model is proposed by replacing the original monotonic cutting force distribution with this combined Hertz-Weibull model.The proposed model outperforms the original CSM model as demonstrated by a comparison of the estimated cutting forces with those from the tests/simulations.The findings from this work that advance our understanding of TBM cutter performance have important implications for improving the efficiency and reliability of TBM tunnelling in granite.

From concept to reality-A review to the primary test stand and its preliminary application in high energy density physics

Pulsed power technology,whereas the electrical energy stored in a relative long period is released in much shorter timescale,is an efficient method to create high energy density physics(HEDP)conditions in laboratory.Around the beginning of this century,China Academy of Engineering Physics(CAEP)began to build some experimental facilities for HEDP investigations,among which the Primary Test Stand(PTS),a multi-module pulsed power facility with a nominal current of 10 MA and a current rising time~90 ns,is an important achievement on the roadmap of the electro-magnetically driven inertial confinement fusion(ICF)researches.PTS is the first pulsed power facility beyond 10 TW in China.Therefore,all the technologies have to be demonstrated,and all the engineering issues have to be overcome.In this article,the research outline,key technologies and the preliminary HEDP experiments are reviewed.Prospects on HEDP research on PTS and pulsed power development for the next step are also discussed.

Numerical study on magneto-Rayleigh–Taylor instabilities for thin liner implosions on the primary test stand facility

The thin aluminum liners with an aspect ratio R/?r 1 have been imploded on the primary test stand(PTS) facility,where R is the outer radius of the liner and ?r is the thickness. The x-ray self-emission images present azimuthally correlated perturbations in the liner implosions. The experiments show that at-10 ns before the stagnation, the wavelengths of perturbation are about 0.93 mm and 1.67 mm for the small-radius and large-radius liners, respectively. We have utilized the resistive magnetohydrodynamic code PLUTO to study the development of magneto-Rayleigh–Taylor(MRT) instabilities under experimental conditions. The calculated perturbation amplitudes are consistent with the experimental observations very well. We have found that both mode coupling and long implosion distance are responsible for the more developed instabilities in the large-radius liner implosions.

DEVELOPMENT OF PT PUMP AND INJECTOR TEST STANDS FOR CUMMINS ENGINE

The type PT-821 PT Pump test stand and type PT-881 injector test stand are a set of special test stands for calibration of PT Pumps and injectors of Cummins engines. Both test stands may be used in conjunction with any model of Bosch injection pump test benches for PT Pumps and injector calibration. During PT Pump calibration, the type PT-821 test stand should be used in conjunction with a Bosch injection pump lest bench. The PT Pump to be tested is installed on the Bosch injection pump test bench through a mounting bracket and is driven by the bench shaft. When calibrating PT injectors, both the PT-881 injector test stand and the PT-821 PT Pump test stand should be used in conjunction with a Bosch injection pump test bench, with the PT-881 injector test stand installed on Bosch test bench. The injector to be tested is driven by the Bosch injection pump test bench through a coupling. This paper describes the structure and function of the PT-821 PT Pump test stand and PT-881 injector test stand. Some technical problems arc described in detail.

基于TestStand的DCS系统级冗余功能自动测试方法

阐述基于Test Stand自动化测试管理框架在集散控制系统(DCS)系统级冗余功能测试上的应用。冗余功能是保证DCS稳定性和可靠性的典型容错技术,其实现方法是当正在运行的子系统出现故障时,将其从系统中切除,并尽快将备用子系统投入应用。该过程本身需要进行详尽的测试,保证切换机制、切换前后系统输入输出以及程序处理符合预期;同时该过程的测试和DCS基本功能需同时进行,观察项、激励源种类多。用Lab VIEW语言编写子模块控制NI板卡和仪表,给系统激励,采集系统输出;用Python语言编写协议层相关函数,给控制器注入故障、模拟上位机操作等。Test Stand自动化测试框架统一并行调度子模块和函数,形成测试序列,提高该项测试的覆盖率、频率、强度、一致性。

Effects of Tuned Mass Damper on Wind-Induced Vibration of Free Standing Pylon by Wind Tunnel Test

In order to assess the effects of tuned mass dampers （TMDs） on wind actions, an aeroelastic model with a scale of 1：60 was constructed. Tests were performed in an atmospheric boundary layer wind tunnel to investigate the buffeting response of the pylon with a TMD fixed by a wire rope instead of a spring. The model was tested under different levels of damping. The experimental and numerical results showed that with the TMD in the optimal condition, the buffeting response was reduced by 47%.

Room-temperature test system for 162.5 MHz high-power couplers

Fundamental power couplers are crucial components for feeding radio frequency power to accelerating cavities. Couplers must be tested and conditioned on a room-temperature test stand to evaluate and potentially improve their performance before being installed in an accelerating cavity. A new test system has been designed and is under construction at the institute of modern physics.For this test system, multiple conditioning modes, including the pulse mode, CW mode, and amplitude-sweeping mode, have been embedded in the low-level radio frequency system of the test stand. All of these conditioning modes can be run manually or automatically. In addition, a novel test cavity is proposed and has been designed, which facilitates non-contact conditioning and a multi-purpose test stand.

First normative reference of standing long jump indicates gender difference in lower muscular strength of Macedonian school children

Background: This is the first study to publish the normative reference values for assessment of the level of muscular strength through the “standing long jump” test carried out on a large sample of Macedonian school children. The normative values encompass a wide span of years (6 - 18). Methods: The research was realized in a large sample of 12618 school children at the age of 6 to 18 years from Macedonia. The sample was divided in 14 groups, according to chronological age and each age group was divided into two subgroups according to the criteria of gender. For estimation of the morphologic characteristics, the following anthropometric measures have been applied: body height in standing position (cm), body weight (kg), as well as the body mass index (BMI). Children aged 6 or above were invited to take a standing long jump test. Results: Boys show statistically better results in all age categories in the standing long jump test than girls, and these differences become bigger with the increase of age, especially after the 14th year

针刀松解联合Mulligan手法治疗中期膝骨关节炎临床观察

目的:观察针刀松解联合Mulligan手法治疗中度膝骨关节炎的临床效果。方法:选取2019年9月至2020年9月上海中医药大学附属龙华医院和上海中医药大学附属龙华医院金山分院门诊收治的KOA患者120例作为研究对象,按照随机数字表法随机分为针刀组、手法组和联合组,每组40例。针刀组采用单纯针刀治疗,手法组采用Mulligan手法治疗,联合组采用针刀联合Mulligan手法治疗。分别观察2组患者治疗前、治疗后及随访24周骨关节炎指数、疼痛视觉模拟评分变化情况、5次坐立试验情况和2组患者临床疗效情况。结果:与针刀组、手法组比较,联合组在治疗后和随访24周,在疼痛视觉模拟评分、骨关节炎指数评分和5次坐立试验情况改善方面差异均有统计学意义(均P<0.01),联合组临床疗效总有效率为97.50%,明显优于针刀组(92.10%)和手法组(75.00%),差异有统计学意义(P<0.05)。结论:针刀联合Mulligan手法治疗中度膝骨关节炎,在改善患者关节疼痛、僵硬和活动不利等症状在近期与远期疗效方面均效果显著,值得临床推广应用。

曲线轨道式隔震装置的结构优化与应用研究

针对浮放物体的防震保护需求,研发出一款基于新型抗侧移组件的曲线轨道式隔震装置。阐述它的构造特点和运行机制,并依据结构原理制作模型,通过试验与理论对比来检验模型的运行质量进而验证方案的可行性。然后结合雨花阁内文物来设计样机,采用多条楼面波进行样机的振动台试验,测试其隔震效果。最后探讨建筑滤波效应对该类隔震装置设计的影响。研究结果表明:曲线轨道式隔震装置经优化后不仅零部件功能清晰,结构简单易加工,而且具备整体性强、运行质量高以及后期可扩展等优势。试验模型的零部件能充分发挥各自功能,尤其是抗侧移组件极大提高了模型的稳定性和可靠性,理论分析与试验结果吻合良好。结合案例所设计的样机虽具有较好的隔震性能,但限于非线性双自由度的结构特点,重复试验的响应结果存在差异,工程应用中应予以重视。当楼面波不易获取且隔震装置周期远离建筑自振周期时,依据楼面加速度放大系数,将调幅后的原始波作为隔震装置设计依据是可行的且结果偏保守。

隔震装置阻尼机构的参数设计与振动台试验

为了改善浮放物体隔震装置中阻尼力的施加方式,研制出一款阻尼机构。对其构造和工作机理进行阐述,推导出了它的力学特征表达式,并验证了分析模型的准确性。结合某文物隔震装置的目标性能,利用数值方法对阻尼机构的参数进行设计,并对比振动台试验。结果表明:该阻尼机构结构简单,性能稳定;经阻尼参数优化后的隔震装置在满足位移限值的情况下达到了设定的隔震目标;试验与数值分析结果相吻合,证明了阻尼机构参数设计的正确性,同时也检验了隔震装置的安装和运行质量。其中,试验与数值分析结果的吻合程度,尤其是位移时程曲线的吻合程度,可为浮放物体隔震装置的方案对比和质量评估提供思路。

水下控制系统测试台设计及试验研究

针对水下控制模块测试需求,文中设计了一种多功能水下控制模块测试台。水下控制模块(SCM)作为水下生产系统的核心部分,其安装成本高、难度大,且不便于在水下维护,因此,在其入水前必须对其进行严格的功能测试,确保在水下工作的可靠性。首先,对关于水下控制模块测试的相关技术和标准进行研究,得出水下控制模块在测试台上进行的测试主要包括内部静水压力测试、液压内部泄漏测试和液压系统功能测试;然后,基于被测水下控制模块的性能指标对测试台的机械结构和液压系统进行了设计,并对上述测试内容的测试方法进行了研究;最后,通过试验对测试台的测试功能进行验证。文中研究为我国设计和研制国产水下生产系统测试设备提供了宝贵经验。

30秒坐立试验联合慢性阻塞性肺疾病患者自我评估测试评分对运动性低氧的预测价值及临床应用研究

背景慢性阻塞性肺疾病(COPD)是老年患者常见呼吸系统疾病之一,活动时外周经皮血氧饱和度(SpO_(2))下降是普遍存在的现象,与疾病预后存在相关性,目前诱导运动性低氧(EID)的评估结论不一。目的探究适合社区及居家COPD患者诱导EID的方法。方法回顾性选择中日友好医院2021年1月—2023年8月收治的76例COPD稳定期患者为研究对象。收集六分钟步行测试(6MWT)中静息SpO_(2)与运动中最低SpO_(2)(ΔSpO_(2)),以ΔSpO_(2)≥4%为EID判定标准。根据有无EID分为非EID组和EID组,比较两组的肺功能指标、30秒坐立试验(30s STST)ΔSpO_(2)、COPD患者自我评估测试(CAT)评分。探究EID与30s STSTΔSpO_(2)、CAT评分的关系;采用受试者工作特征(ROC)曲线分析30s STSTΔSpO_(2)、CAT评分及二者联合对EID的预测价值。结果非EID组(n=29)与EID组(n=47)中30s STSTΔSpO_(2)、CAT评分比较,差异有统计学意义(P<0.05);30s STSTΔSpO_(2)预测EID截断值为2%,灵敏度为59.6%,特异度为82.8%,ROC曲线下面积(AUC)为0.730(95%CI=0.614~0.846,P<0.05);CAT评分预测EID截断值为13分,灵敏度为48.9%,特异度为79.3%,AUC为0.712(95%CI=0.596~0.828,P<0.05);30s STSTΔSpO_(2)联合CAT评分预测EID的截断值为0.593,灵敏度为70.2%,特异度为72.4%,AUC为0.765(95%CI=0.659~0.871,P<0.001)。结论30s STST诱发SpO_(2)≥2%、CAT评分≥13分,需警惕EID的发生可能;30s STST、CAT评分可以成为社区及居家预测稳定期COPD患者诱导EID的测评方法。

前列腺切除术后尿失禁的诊断与评估

近年来,前列腺癌发病率逐渐升高,根治性前列腺切除术是治疗局限性前列腺癌的标准手术,其中前列腺切除术后尿失禁(PPI)是术后常见的并发症之一,严重影响患者的生活质量。对于药物及保守治疗无效的PPI,需要采用手术方式治疗,目前主要根据临床症状、体格检查及尿动力学检查结果选择具体手术方式,具体手术方式包括人工尿道括约肌植入术、可调节及不可调节男性吊带手术等。因此,准确诊断及评估PPI有助于临床制订更有针对性的治疗方案。

某主燃油泵调节器最小燃油流量不合格故障研究

针对某主燃油泵调节器随发动机试车检查最小燃油流量不合格故障产生的原因,结合发动机工作原理,开展了故障分析及相关改进措施验证;最终确定故障原因为燃油泵调节器调整试验器的测量系统涡轮流量计管路设计前置长度较短、漩涡流动增强、测量误差大导致。通过对试验器系统原理分析,制定改进行措施,在安装测量系统涡轮流量计时,增加其上游直管段长度排除了主燃油泵调节器外场试车最小燃油量不合格故障,而且为后续燃油泵试验器测量系统的设计提供了参考依据,这既保证了发动机工作的可靠性和安全性,同时也提高了试验器测量系统的测量精度。

超越离合器试验台关键部件设计与计算

根据模拟离合器在实际工作状态下试验离合器的工作性能,设计了一种搭载2台异步电动机的超越离合器试验台,2台电动机分别与增速圆柱齿轮箱和减速圆柱齿轮箱配合模拟离合器在实际工作中的驱动模块和加载模块。采用斜齿圆柱齿轮传动齿根危险截面弯曲强度校核公式,对增速圆柱齿轮箱大小齿轮进行强度校核;基于SolidWorks软件Simulation模块对增速箱大小齿轮不同扭矩进行静应力仿真分析;计算传动轴的1、2阶临界转速,判断轴的工作转速是否处在安全范围、增速圆柱齿轮箱传动轴在高速运转过程中是否发生共振现象。为超越离合器相关研究提供参考。

多测试试验台生产计划智能调度优化系统设计与实现

生产计划调度是制造生产的重要步骤,是制造类企业生产运行的指挥中心。生产计划调度即按照一定的规则和要求合理安排若干个生产计划,以确定每个工艺工序的工件产出数量及其出厂时间,从而保证公司的产品出货供应正常,最大化地满足市场需求。制造元器件的测试过程对于确保产品质量至关重要,通过多工位检测对待检测元器件进行多个测试项目试验,可以及时发现并解决这些问题,提高产品的质量。多测试试验台的生产计划调度涉及多个测试工位的先后顺序,存在着复杂的制造流程,市场需求变化,设备故障,工艺流程的调整等因素造成的生产计划调度困难等问题。文中提出一种基于Spring Boot框架以及MySQL数据库的多测试试验台生产计划智能调度优化系统,用以实现对多测试试验台车间的生产计划智能调度,帮助克服多测试试验台的生产计划调度存在的诸多问题。

直立锁边金属屋面风揭破坏全过程分析

直立锁边金属屋面长期服役过程中,由于各种因素的影响,风揭破坏时有发生。国内外学者对其破坏过程及破坏形式进行一定探索,而风揭破坏阶段的划分及各阶段的标志仍缺乏清晰界定。使用自主设计的试验装置,以区域面力代替均布风吸力对直立锁边金属屋面进行静态承载力试验,结合表观现象与3D点云模型研究其破坏过程。研究发现:金属屋面的破坏过程可分为弹性、塑性、强化、失效、后承载力5个阶段,分别对应卸载变形可恢复、咬边处竖向板顶部与支座底部接触、竖向板顶部沿支座底部水平滑移,竖向板与水平夹角迅速扩展、竖向板顶部滑移至支座底部尽头,卷边间缝隙迅速增大、单边脱扣。对于服役状态下的金属屋面,在进入“塑性阶段”后,就已产生不可恢复的永久变形,应及时补强加固。设计时可依据抗风承载力及安全极限荷载给出2种承载限值。

立靶测试系统跨帧技术研究

CCD立靶测试系统用于靶场测试,采集弹丸着靶照片,其关键技术就是CCD高速成像,通常采用造价高昂的高速成像相机采集高速弹丸着靶图片,但由于仅需抓拍着靶瞬间图像,高速相机不适用于现场的立靶测试,因此根据实际情况进行跨帧技术研究,通过造价较低的两个低频率相机实现高频相机的功能,且能够适用于特殊的现场试验要求。

直立锁边金属屋面系统抗风设计与结构承载力试验

直立锁边金属屋面因抗风揭强度不足常出现风揭破坏。为了详细分析直立锁边金属屋面系统的抗风揭性能,首先,提出了抗风设计关键技术问题。然后,对屋面关键部位的风荷载计算和屋面系统的结构抗力进行研究。最后,对如何选择抗风揭试验方法来获得结构承载力进行对比分析。结果表明,在计算屋面风荷载时,应重点关注局部关键部位,采取规范计算和风洞试验相结合的方法进行验证;在确定直立锁边金属屋面系统结构承载力时,需综合考虑抗风揭静态和动态试验结果。