Ramp-Wave Compression Experiment with Direct Laser Illumination on ShenGuang-Ⅲ Prototype Laser Facility

Ramp-wave compression experiment to balance the high compression pressure generation in aluminum and x-ray blanking effect in transparent window is demonstrated with an imaging velocity interferometer system for any reflector （VISAR） on ShenGuang-Ⅲprototype laser facility. The highest pressure is about 500 GPa after using the multilayer target design Al/Au/Al/LiF and -10^13 W//cm2 laser pulse illuminated on the planar Al target, which generates the spatial uniformity to 〈1% over 500 μm on the ablation layer. A 2-μm-thick Au layer is used to prevent the x-ray from preheating the planar ablation Al layer and window material LiF. The imaging VISAR system can be used to record the abrupt loss of the probe beam （λ= 532 nm） caused by absorption and reflection of 20-μm, 30-μm and 40-μm-thick Al, i.e., the blanking effect. Although there are slight shocks in the target, the peak pressure 500 GPa, which is the highest data up to now, is obtained with ramp-wave compression.

Experiments and 3D DEM of Triaxial Compression Tests under Special Consideration of Particle Stiffness

Discrete element modelling is commonly used for particle-scale modelling of granular or particulate materials. Developing a DEM model requires the determination of a number of micro-structural parameters, including the particle contact stiffness and the particle-particle friction. These parameters cannot easily be measured in the laboratory or directly related to measurable, physical material parameters. Therefore, a calibration process is typically used to determine the values for use in simulations of physical systems. This paper focuses on how to define the particle stiffness for the discrete element modelling in order to perform realistic simulations of granular materials in the case of linear contact model. For that, laboratory tests and numerical discrete element modelling of triaxial compression tests have been carried out on two different non-cohesive soils i.e. poorly graded fine sand and gap graded coarse sand. The results of experimental tests are used to calibrate the numerical model. It is found that the numerical results are qualitatively and quantitatively in good agreement with the laboratory tests results. Moreover, the results show that the stress dependent of soil behaviour can be reproduced well by assigning the particle stiffness as a function of the particle size particularly for gap graded soil.

Experimental Analysis of a Compressed Air Engine

Nowadays, automobiles consume a large number of fossil fuels. However, the consumption of fossil fuels has brought many serious environmental problems, such as global warming, ozone layer depletion and fine particulate matter. To avoid such environmental problems, renewable energy has been applied to automobiles. In this paper, an air-powered engine of a renewable energy vehicle is introduced. To lay a foundation for the optimization of compressed air engine (CAE), a physical model of compressed air engine (CAE) is established with cam which controls compressed air charge or discharge cylinder. To obtain performance of the CAE, a prototype CAE system is set up. The output torque, power and efficiency are obtained through experimental study. The results show that the prototype of CAE has a good economic performance under low speed and when the supply pressure is 2 MPa, the maximum output power is 1.92 kW;the maximum output torque is 56.55 N·m;and the maximum efficiency is 25%. This research can be referred to in the optimization of air-powered engine.

Axial Compression Behavior and Analytical Method of L-Shaped Column Composed of Concrete-Filled Square Steel Tubes

Based on the characteristics of an L-shaped column composed of concrete-filled square steel tubes, the axial compression experiment and nonlinear finite element analysis were carried out to study the mechanical property of the L-shaped column. The load-displacement curve for the L-shaped column, the deflection and load-strain curves for the mono columns were obtained by the axial compression experiment. The results show that the L-shaped column exhibits a flexural-torsional buckling failure mode. The numerical simulation by the finite element analysis shows that the bearing capacity and failure mode are in accordance with those of the axial compression experiment and the feasi- bility of the finite element analysis is proved. For the calculation of the bearing capacity of the L-shaped column com- posed of concrete-filled square steel tubes, an analytical method is proposed based on the theory of the elastic stability and spatial truss model. The results of the analytical method are in good agreement with those of the axial compression experiment and the finite element analysis.

STUDY ON THE POST-STALL BEHAVIOR OF AN AXIAL-FLOW COMPRESSION SYSTEM

Post stall behaviors of a single stage compression system are studied theoretically and experimentally in this paper. A one dimensional nonlinear model, which is able to describe the dynamically post stall behaviors of the compression system, is applied to simulate the post stall behaviors digitally. The stall types, i.e. , rotating stall and surge, are determined. The variations of annular average parameters while the compression system goes into stall are also calculated exactly. The post stall behaviors are measured on the single stage compressor test rig. The measurement shows that rotating stall and surge appear under different conditions. On the basis of experiments, it is found that the post stall behaviors are influenced remarkably by some factors, such as rotation speeds, construction type and size of the exhaust duct. Good agreement between the simulation and experiments proves that this modeling technique is valid for simulating the post stall behaviors.

“Compression Dynamometamorphic Solid Bitmen” and Its Significance in Oil and Gas Exploration

There is natural occurrence of pressure-induced solid bitumen, here referred to as “compression dynamometamorphic solid bitumen”. It differs in physical properties and chemical structure from thermal metamorphic solid bitumen. Under a high pressure and moderate temperature, the solid bitumen forms crystals and its reflectance rises rapidly with increasing crystallization. Accordingly, its reflectance can reach a very high value without having been exposed to a high level of thermal stress. Laboratory simulation confirms the formation of pressure-induced solid bitumen at moderate temperatures. The revelation of this new bitumen type is very helpful in the accurate maturity determination of carbonate organic matter.

Prediction of Load-Displacement Curve of Flexible Pipe Carcass Under Radial Compression Based on Residual Neural Network

The carcass layer of flexible pipe comprises a large-angle spiral structure with a complex interlocked stainless steel cross-section profile, which is mainly used to resist radial load. With the complex structure of the carcass layer, an equivalent simplified model is used to study the mechanical properties of the carcass layer. However, the current equivalent carcass model only considers the elastic deformation, and this simplification leads to huge errors in the calculation results. In this study, radial compression experiments were carried out to make the carcasses to undergo plastic deformation. Subsequently, a residual neural network based on the experimental data was established to predict the load-displacement curves of carcasses with different inner diameter in plastic states under radial compression.The established neural network model’s high precision was verified by experimental data, and the influence of the number of input variables on the accuracy of the neural network was discussed. The conclusion shows that the residual neural network model established based on the experimental data of the small-diameter carcass layer can predict the load-displacement curve of the large-diameter carcass layer in the plastic stage. With the decrease of input data, the prediction accuracy of residual network model in plasticity stage will decrease.

局部麻醉下机器人辅助经皮椎体后凸成形伤椎注入骨水泥的患者体验分析

背景:局部麻醉下传统C臂辅助经皮椎体后凸成形手术需多次透视以调整穿刺方向,工作通道建立时间较长,患者术中疼痛刺激较大;而机器人辅助经皮椎体后凸成形手术可一次性精准穿刺成功,明显改善患者术中体验,同时减少骨水泥渗漏风险。目的:比较局部麻醉下机器人辅助和传统C臂辅助经皮椎体后凸成形手术的患者体验和其他疗效。方法:选择四川省医学科学院·四川省人民医院(电子科技大学附属医院)收治的单节段骨质疏松性椎体压缩骨折患者241例,其中132例在局部麻醉下进行机器人辅助经皮椎体后凸成形手术治疗(机器人辅助组),109例在局部麻醉下进行传统C臂辅助经皮椎体后凸成形手术治疗(传统透视组),记录患者术中体验评价、骨水泥注射量、手术时间、工作通道建立时间、住院费用及并发症,术后1 d通过影像学评估穿刺偏差与骨水泥渗漏。结果与结论:(1)机器人组59例患者术中体验评价为“非常好”,43例为“好”,16例为“一般”,10例为“差”,4例为“非常差”;传统透视组30例患者术中体验评价为“非常好”,44例为“好”,21例为“一般”,9例为“差”,5例为“非常差”,两组间术中体验评价比较差异有显著性意义(Z=-2.546,P=0.011);机器人组患者术中目测类比评分低于传统透视组(t=-9.513,P=0.000);机器人组、传统透视组愿意在必要时再次接受经皮椎体后凸成形手术的患者分别为84例和47例,组间比较差异有显著性意义(Z=-2.730,P=0.006);(2)机器人组患者手术时间、住院费用均多于传统透视组(t=2.860,P=0.003;t=36.522,P=0.000),工作通道建立时间短于传统透视组(t=-27.066,P=0.000),穿刺精度优于传统透视组(Z=-3.656,P=0.000),骨水泥渗漏率低于传统透视组(χ^(2)=7.284,P=0.007);(3)结果表明,局部麻醉后在机器人辅助行经皮椎体后凸成形手术患者的手术体验较好,具有穿刺精确、工作通道建立时间短、骨水泥渗漏率低的优势。

体外实验中压应力对细胞的作用和影响

背景:沃尔夫定律指出,机体缺乏机械应力会导致骨组织的微结构退化、质量损失和代谢紊乱,并最终导致骨质疏松症,这提示机械应力在骨组织生长、重建及成形中具有重要作用。目前机械应力对成骨细胞的相关研究主要集中在流体剪切力上,但其在体内干预较为困难,同时有研究发现压应力在一定程度上也可以起到与流体剪切力类似的作用,探究压应力在体外对细胞的作用方式和影响,可以丰富机械应力与细胞的相互作用关系,有助于为包括骨质疏松在内的代谢性骨病和其他疾病的研究提供理论依据。目的:综述体外实验中压应力对细胞的施加方式、引起细胞产生不同的生物学行为、可能的作用信号途径以及未来可能应用的领域。方法:检索PubMed、Web of Science、中国知网及万方数据库2000年1月至2024年3月发表的相关文献,中文检索词为“压应力,机械应力,静水压力,细胞”,英文检索词为“compressive stress,mechanical stress,hydrostatic pressure,cell”。纳入压应力作用于细胞的基础研究及微观机制研究,最终对纳入的63文献进行综述。结果与结论:(1)压应力的施加方式多样,不同实验设备对细胞加载压应力的方式不尽相同,需要进一步规范实验设备和标准化力学单位,减少混杂因素,使不同实验组之间具有参考性和可比性;(2)压应力可引起细胞增殖、分化、自噬、凋亡、迁移等变化,且在多数情况下压应力的作用效果具有时间或剂量依赖性;(3)目前大部分体外实验研究表明,压应力可能主要是通过MAPK信号途径、Wnt/β-catenin信号通路作用于成骨细胞,引起成骨细胞产生不同的应答;(4)压应力可对不同细胞产生不同的作用效果,还需要进一步研究其对不同组织的生物学作用;(5)对压应力的更深入研究有助于为骨科、口腔、肿瘤等疾病的治疗提供理论依据,利用静水压力进行温和消毒是一种前景巨大的消毒手段。

Effect of compressive strength on the performance of the NEMO-LIM model in Arctic Sea ice simulation

Satellite records show that the extent and thickness of sea ice in the Arctic Ocean have significantly decreased since the early 1970s.The prediction of sea ice is highly important,but accurate simulation of sea ice variations remains highly challenging.For improving model performance,sensitivity experiments were conducted using the coupled ocean and sea ice model(NEMO-LIM),and the simulation results were compared against satellite observations.Moreover,the contribution ratios of dynamic and thermodynamic processes to sea ice variations were analyzed.The results show that the performance of the model in reconstructing the spatial distribution of Arctic sea ice is highly sensitive to ice strength decay constant(C^(rhg)).By reducing the C^(rhg) constant,the sea ice compressive strength increases,leading to improved simulated sea ice states.The contribution of thermodynamic processes to sea ice melting was reduced due to less deformation and fracture of sea ice with increased compressive strength.Meanwhile,dynamic processes constrained more sea ice to the central Arctic Ocean and contributed to the increases in ice concentration,reducing the simulation bias in the central Arctic Ocean in summer.The root mean square error(RMSE)between modeled and the CryoSat-2/SMOS satellite observed ice thickness was reduced in the compressive strength-enhanced model solution.The ice thickness,especially of multiyear thick ice,was also reduced and matched with the satellite observation better in the freezing season.These provide an essential foundation on exploring the response of the marine ecosystem and biogeochemical cycling to sea ice changes.

Structure design and compression experiment of the supporting node for JUNO PMMA detector

Introduction Jiangmen Underground Neutrino Observation is going to build a huge polymethyl methacrylate(PMMA)detector to hold 20,000 tons of liquid scintillator to capture neutrinos in a 700-m underground cave.This PMMA detector has a spherical shape with an inner diameter of 35.4 m and is supported by an outside stainless steel structure through 590 supporting nodes.The maximum compression force applied to these supporting nodes would be about 150 kN when the detector is running.Method This paper focuses on the design and validation of the PMMA supporting node and compares the effects of two gaskets(round gasket and ring gasket)on the supporting node stress and ultimate compression load.An innovative PMMA supporting node structure is first proposed,and a 1/4 symmetric model with the material nonlinearity and frictional contact boundary is established in the finite element analysis(FEA).Results The FEA results show that the principal stress of the structure is less than 3.5 MPa and the Mises stress is less than 5.5 MPa.The stress and deformation at the groove of the supporting node using the ring gasket are smaller than that using the round gasket.The compression experiments of the supporting node using two types of gaskets were conducted to study the effect of gaskets on the ultimate compression load of supporting node.The ultimate compression load of the supporting node with ring gasket is larger than 900 kN,which is six times of design load.In a comparison of experimental results with FEA,the maximum difference is 15.78%,demonstrating the validity of FEA results.Through the material test of PMMA and experiment of the PMMA supporting node,it is known that PMMA is a brittle material and it is very sensitive to sharp corner defects that should be avoided in the design of PMMA structure.

Compressive properties of open-cell ceramic foams

The compressive experiments of two kinds of ceramic foams were completed. The results show that the behavior of ceramic foams made by organic filling method is anisotropic. The stress-strain responses of ceramic foams made by sponge-replication show isotropy and strain rate dependence. The struts brittle breaking of net structure of this ceramic foam arises at the weakest defects of framework or at the part of framework, which causes the initiation and expanding of cracks. The compressive strength of ceramic foam is dependent on the strut size and relative density of foams.

Clinical experience in treating 78 cases of upper limb edema after breast cancer operation by WenYang HuoXue Washing Prescription

Objective To observe the clinical efficacy and safety of WenYang HuoXue Washing Prescription （WYHX） in the treatment of upper limb edema after breast cancer surgery. Methods： Seventy-eight patients with upper extremity edema after operation of breast cancer with Yin Syndrome were given wet compress with prescription and nursing guidance. The symptom score of affected extremity was observed before and 14 days after treatment, and the total effective rate was evaluated. Results： Twenty-three cases were markedly effective, 41 cases were effective and 14 cases were Invalid. The total effective rate was 82.1%. There was no significant difference between the two groups according to stage I and stage II of edema （P 〉 0.05）. Conclusion： WYHX can effectively improve the discomfort symptoms of upper limb edema and cold after breast cancer surgery, and is worthy of clinical application.

植生混凝土的配制及植生性能研究

配制植生混凝土的关键是解决混凝土强度和碱度之间的矛盾。通过化学降碱法、物理降碱法、物理降碱和农艺降碱相结合的方法,研究了水胶比、粉煤灰掺量、矿粉掺量、硅灰掺量、减水剂掺量等因素对植生混凝土抗压强度、孔隙环境pH值、孔隙率的影响,并对种植方式和植物品种进行优选试验。结果表明:最优配合比下,植生混凝土28 d抗压强度为13.4 MPa,pH值为11.0,并不能满足植生需求;采用物理降碱和农艺降碱相结合的方法,经处理后植生混凝土28 d抗压强度为12.4 MPa,pH值为8.8;高羊茅作为适生植物,在植生混凝土上生长状态良好。

乌兰木伦煤矿大断面硐室围岩变形破坏规律及控制

针对煤矿井下巷道大断面硐室的围岩变形破坏问题,以乌兰木伦煤矿井下分选及充填大断面硐室为研究对象,采用相似模拟实验方法,进行单调递增加载和恒定荷载加载单轴压缩实验,对大断面硐室围岩变形破坏规律进行了研究。结果表明:①2种加载方式在压密阶段、弹性变形阶段及微破裂稳定发展阶段破坏演化和变形位移趋势相似。②采用单调递增加载方式的试样裂纹较少但裂纹缝隙较大,试样沿着主裂纹突然发生破断,期间有大量碎屑飞出,试样变形位置主要集中在围岩边界,破坏时释放能量较多,但峰后释放能量持续时间较短。③采用恒定荷载加载方式的试样应力保持不变,应变缓慢增加,期间产生大量微小裂纹,试样变形位置主要围绕在硐室周围,破坏时释放能量较少,但峰后释放能量持续时间较长。依据大断面硐室围岩变形破坏规律,提出了锚杆索支护方案:硐室顶部打长锚索,将顶板和上方坚硬岩石连成整体;在硐室煤岩交界处打倾斜锚杆,将煤岩交界面与周围岩体紧密连接。数值模拟结果表明,支护后围岩应力、位移、塑性区均明显减小,围岩稳定性大幅提高,支护效果良好。

超深碳酸盐岩储层岩石三轴压缩实验与数值模拟研究

为了研究超深碳酸盐岩储层的岩石力学特性,文中以取自埋深约8350 m的顺北油气田奥陶系储层碳酸盐岩真实岩样为研究对象,按热处理与无热处理,在110 MPa围压范围内进行三轴压缩实验,从而得到高围压下的岩石力学特性。实验结果表明:高围压下,岩石表现强烈的塑性流动,加热处理会使得岩石强度降低,但随着围压等级的升高,不同温度下的岩石峰值应力又趋于一致。基于Drucker-Prager屈服准则,发展了塑性硬化参数与等效塑性应变之间的关系,对2种温度下的岩石三轴压缩实验进行数值模拟,结果很好地再现了三轴压缩应力-应变曲线。作为拓展应用,采用所建立的弹塑性本构对单条裂缝压裂过程进行模拟,发现在本岩样所在的储层条件下,压裂过程中的裂缝扩展不受岩石塑性的影响,这一点与裂缝闭合过程完全不同,这为目标储层压裂改造提供了有意义的借鉴。

排气道压力波动对发动机二冲程减压制动性能的影响

为分析排气管内压力波动对发动机二冲程制动功率的影响,以某重型柴油机为研究对象,利用GT-Power建立发动机二冲程制动一维模型,通过修改排气型线开展排气道压力波动对制动性能影响的研究。结果表明:第二次减压制动(the second compression release braking,2nd CRB)相位开启时的压力波动会影响到其他气缸的排气回流,进而影响发动机的制动功率。进一步对排气管进行三维流场计算,证明了其他气缸2nd CRB相位排气门开启时的压力波传递对排气回流阶段排气回流的影响。最后通过试验设计(design of experiment,DoE),结合响应面拟合和粒子群算法对排气管几何尺寸进行优化,优化后该柴油机二冲程减压制动模式下2100 r/min工况的最大制动功率可达到395.08 kW。

碳酸盐岩地层超压预测模型研究及应用

碳酸盐岩地层超压预测是目前国内外尚未解决的基础性难题。以川东北地区超压碳酸盐岩地层为研究对象,通过物理模拟实验研究碳酸盐岩弹性参数随围压和孔压的变化规律,提出了基于岩石孔隙压缩系数的碳酸盐岩地层超压预测模型。实验结果显示,碳酸盐岩孔隙度的增大和岩样弹性参数变化与孔隙压力增量之间存在一定的相关性,据此建立岩石孔隙压缩系数与孔隙压力、孔隙体积的理论关系,并推导出超压预测模型,模型考虑了区域构造应力的影响,参数可以通过实验和测井资料获得;利用密度、声波和中子测井资料开展典型钻井超压预测,预测结果与实测压力吻合良好。新提出的超压预测模型为碳酸盐岩地层超压预测提供了新思路。

轻质多孔结构制备及响应面优化

多孔结构作为新型建筑材料结构,目前依然存在制备材料最佳配比不准确、结构材料与植物相容性差等问题影响其应用。为确定制备多孔结构最佳材料配比,提高其力学强度的同时具有良好植生空间,文章采用轻质多孔火山石作为粗骨料,水泥、粉煤灰、拌合水搅拌而成的胶凝浆体作为胶结剂,制作轻质多孔材料,开展相关的多孔结构制备试验并探究其不同单因素水平下的物理力学性能,得到合理的配合比范围,并采用响应面进行优化,得到满足一定抗压强度、具有良好植生空间及透水性能的最佳材料配合比。结果如下:(1)抗压强度随着水灰比增大呈现先增大后减小的变化趋势,最佳水灰比约0.35,骨料粒径越小,多孔结构抗压强度越高,但为了满足多孔性和透水性,选取2 cm左右的骨料较为适宜;(2)胶凝浆体中胶凝材料由质量占比75%的水泥与25%的粉煤灰组成,并含有0.1%的减水剂,应控制浆体含量为15%~25%,且不应超过30%;(3)根据响应面优化分析,制备多孔结构最优化配合比为:骨料粒径约2 cm,水灰比0.377,胶凝材料体积含量20.7%,在该配比下孔隙率、有效孔隙率和透水系数分别为:38.3%、33.5%、2.98 cm/s。最佳配比下的多孔结构既满足其力学要求,同时具有良好的植物相容性,研究成果可为多孔结构的制备与应用提供科学依据。

基于大鼠模型的磁压榨吻合与机械压榨吻合的对比实验研究

目的基于大鼠回肠侧侧吻合模型进行磁压榨吻合与机械压榨吻合的对比实验研究,比较2种吻合方式的效果差异。方法将40只大鼠随机平均分为实验组与对照组进行回肠侧侧吻合。实验组使用磁压榨吻合装置(Magnetic Compression Device,MCD),对照组使用机械压榨吻合装置(Simple Compression Device,SCD),吻合装置直径均为6m m。结果在手术时间方面,MCD组耗时显著少于SCD组(P<0.001),这表明MCD在手术操作性上较SCD具有一定优势;MCD组与SCD组在存活率(P=0.548>0.05)、吻合口形成时间(P=0.062>0.05)、吻合口大小(P=0.754>0.05)、爆破压(P=0.533>0.05)、吻合口抗张强度(P=0.336>0.05)方面差异均无统计学意义。结论磁压榨吻合与机械压榨吻合均安全、可靠,且在磁压榨吻合过程中,磁力起主导作用。