Experimental Research of Resistance on Deep Sea Buoys and Mooring Systems

-In this paper a series of model experiments of resistance on buoys and mooring system components are described. The experiments include: experiments of hydrodynamic resistance on buoys and mooring system components, and experiment of air resistance on buoys in wind tunnel. The results are compared with the Beto's results (1980) and some analyses are conducted. The experimental results provide a reliable basis and some parameters for the design of deep sea mooring systems.

Experimental Study on Influencing Factors of Resistance Coefficient and Residual Resistance Coefficient in Oilfield Z

In order to clarify the major influence factors of resistance coefficient and residual resistance coefficient, so as to provide the basis for optimizing the polymer flooding schemes in oilfield Z of Bohai Sea, artificial cores were made by simulated the characteristic parameters of real reservoir and the spacing of production-injection wells. The main parameters considered include reservoir permeability, polymer solution concentration and polymer injection rate. Core experiment of polymer flooding was taken by considering all the main parameters. The result showed that resistance coefficient and residual resistance coefficient decrease with the increase of core permeability. Resistance coefficient and residual resistance coefficient increase with the increase of concentration of polymer solution. The increment of displacement pressure in low permeability core is higher than in medium and high permeability core. The resistance coefficient increase with higher displacing velocity, and the increment in high permeability core is higher than in low permeability?core. The displacement velocity has little effect on the residual resistance coefficient. The experimental results can effectively guide the formulation of polymer flooding scheme in offshore oilfields, and optimize the appropriate injection rate and concentration of polymer solution for different properties of reservoirs, thus ensuring the effectiveness of polymer flooding in offshore oilfields.

Electromagnetic anomaly before earthquakes measured by electromagnetic experiments

Three experiments are carried out for earthquake monitoring using electromagnetic （EM） methods in recent years. Some earthquakes occurred in chance of the measurement time period for each experiment and the anomalies were recorded before the shocks. The observation at a site 20 km away from the epicenter of Zhangbei Ms6.2 earthquake in 1998 shows that the apparent resistivity decreases in the strike direction before and/or during the earthquake and the resistivity increases in the decline direction. This anomalous variation in apparent resistivity accounts for about 20%. The apparent resistivities at a site in the epicentral area decrease in the strike and decline directions before and/or during the earthquake and increase after shocks. The experiments using artificial electromagnetic signals with super low frequency carried out in 1999 show that the resolution and stability of electric and magnetic spectra are improved. The spectra of electric and magnetic fields and apparent resistivity at the Baodi station began to anomalously change two days before the Qian＇an earthquake with 120 km distant to the station. The anomalous variation of electric and magnetic spectra is about twice as great as normal variation and the apparent resistivity changes by about 20%. The measurements in active seismic area of Yunnan province in the year 2005 indicate that the electric and magnetic spectra anomalously change by one order before the Taoyuan earthquake about 100 km away from the observatories. But the measurements at the sites in Beijing area 2 000 km away from the epicenter do not show any anomaly.

Centrifuge experiment on the penetration test for evaluating undrained strength of deep-sea surface soils

Rapid advances in deep-sea mining engineering have created an urgent need for the accurate evaluation of the undrained strength of marine soils,especially surface soils.Significant achievements have been made using full-flow penetration penetrometers to evaluate marine soil strength in the deep penetration;however,a method considering the effect of ambient water on the surface penetration needs to be established urgently.In this study,penetrometers with multiple probes were developed and used to conduct centrifuge experiments on South China Sea soil and kaolin clay.First,the forces on the probes throughout the penetration process were systematically analyzed and quantified.Second,the spatial influence zone was determined by capturing the resistance changes and sample crack development,and the penetration depth for a sample to reach a stable failure mode was given.Third,the vane shear strength was used to invert the penetration resistance factor of the ball and determine the range of the penetration resistance factor values.Furthermore,a methodology to determine the penetration resistance factors for surface marine soils was established.Finally,the effect of the water cavity above various probes in the surface penetration was used to formulate an internal mechanism for variations in the penetration resistance factor.

Effects of simulated submerged and rigid vegetation and grain roughness on hydraulic resistance to simulated overland flow

Better understanding of the role of vegetation and soil on hydraulic resistance of overland flow requires quantitative partition of their interaction. In this paper, a total of 144 hydraulic flume experiments were carried out to investigate the hydraulic characteristics of overland flow. Results show that hydraulic resistance is negatively correlated with Reynolds number on non-simulated vegetated slopes, while positively on vegetated slopes. The law of composite resistance agrees with the dominant resistance, depending on simulated vegetation stem,surface roughness, and discharge. Surface roughness has greater influence on overland flow resistance than vegetation stem when unit discharge is lower than the low-limited critical discharge, while vegetation has a more obvious influence when unit discharge is higher than the upper-limited critical discharge. Combined effects of simulated vegetation and surface roughness are unequal to the sum of the individual effects through t-test, implying the limitation of using linear superposition principle in calculating overland flow resistances under combined effect of roughness elements.

Bending Resistance of Steel Plate-Reinforced Concrete Beam

The formulas for calculating bending-resistant capacity of a steel plate-reinforced concrete composite beam are derived. To validate the formulas, experiments of the composite beam under three-point bending are carried out. Calculated results based on the formulas are in good agreement with experimental results.

Some results of modeling D-D seismogenic pattern by the fracture model experiment of large-scale rock samples(I)

sing the natural limestone samples taken from the field with dimension of 500 mm×500 mm×1 000 mm, the D-D (dilatancy-diffusion) seismogeny pattern was modeled under the condition of water injection, which observes the time-space evolutionary features about the relative physics fields of the loaded samples from deformation, formation of microcracks to the occurrence of main rupture. The results of observed apparent resistivity show: ① The process of the deformation from microcrack to main rupture on the loaded rock sample could be characterized by the precursory spatial-temporal changes in the observation of apparent resistivity; ② The precursory temporal changes of observation in apparent resistivity could be divided into several stages, and its spatial distribution shows the difference in different parts of the rock sample; ③ Before the main rupture of the rock sample the obvious ″tendency anomaly′ and ′short-term anomaly″ were observed, and some of them could be likely considered as the ″impending earthquake ″anomaly precursor of apparent resistivity. The changes and distribution features of apparent resistivity show that they are intrinsically related to the dilatancy phenomenon of the loaded rock sample. Finally, this paper discusses the mechanism of resistivity change of loaded rock sample theoretically.

Key Technology and Experimental Results of the Clean Air Heated Facility for Supersonic Combustion

The scramjet, which is the propulsion of hypersonic vehicle, has become the focus in many military developed countries. The ground tests play an important role in the research of scramjet. There is defect of test medium contamination （the thermochemical characteristic of the ground test medium is different from that of the flight medium） in existing ground test facilities for scramjet combustor experiment. To solve the problem of test medium contamination, the first clean air heated facility of China for scramjet combustor experiment is designed. The key technology of designing the clean air heated facility is summarized. By using bypass duct, combustor model is protected from high temperature. To reduce the switching time between main duct and bypass duct, solenoid valve and water-cooled system were used. Having centrosymmetric structure, the heat radiating area of the facility and heat loss of the facility are much lower than others. Clean air heated facility is adopted to conduct experiment, which is the first experiment of China in clean air inflow, research on hydrogen-fueled and ethylene-fueled ignition and combustion for scramjet combustor at different equivalence ratio. Successful ignition and sustained combustion of hydrogen has been achieved. Successful ethylene ignition and sustained main stream combustion is achieved with normal fuel injection and taking hydrogen as pilot flame. Experiment result shows that the wall pressure of combustor model rises when the equivalence ratio of hydrogen rises. As the wall pressure of combustor model rises, the pressure disturbance influences the shock train in the upstream.

Input signal design to estimate interwell connectivities in mature fields from the capacitance-resistance model

Interwell connectivities are fundamental parameters required to manage waterfloods in oil reservoirs. Data-driven models, such as the capacitance-resistance model （CRM）, are fast tools to estimate these parameters from time-correlations of input （injection rates） and output （production rates） signals. Noise and structure of the input time-series impose limits on the information that can be extracted from a given data-set. This work uses the CRM to study general prescriptions for the design of input signals that enhance the information content of injection/production data in the estimation of well-to-well interactions. Numerical schemes and general features of the optimal input signal strategy are derived for this problem.

Optimization of friction stir welding parameters for improved corrosion resistance of AA2219 aluminum alloy joints

The aluminium alloy AA2219(Al—Cu—Mg alloy) is widely used in the fabrication of lightweight structures with high strength-to-weight ratio and good corrosion resistance.Welding is main fabrication method of AA2219 alloy for manufacturing various engineering components.Friction stir welding(FSW) is a recently developed solid state welding process to overcome the problems encountered in fusion welding.This process uses a non-consumable tool to generate frictional heat on the abutting surfaces.The welding parameters,such as tool pin profile,rotational speed,welding speed and axial force,play major role in determining the microstructure and corrosion resistance of welded joint.The main objective of this work is to develop a mathematical model to predict the corrosion resistance of friction stir welded AA2219 aluminium alloy by incorporating FSW process parameters.In this work a central composite design with four factors and five levels has been used to minimize the experimental conditions.Dynamic polarization testing was carried out to determine critical pitting potential in millivolt,which is a criteria for measuring corrosion resistance and the data was used in model.Further the response surface method(RSM) was used to develop the model.The developed mathematical model was optimized using the simulated annealing algorithm optimizing technique to maximize the corrosion resistance of the friction stir welded AA2219 aluminium alloy joints.

一种天然蓝色素可降解膜的制备及其油脂抗氧化性研究

目的将真菌Pseudofusicoccum violaceum F10产的天然蓝色素添加到明胶基膜中制备成可降解抗氧化性膜,并探究该膜的抗氧化性能。方法将天然蓝色素按一定比例添加到明胶、羧甲基纤维素钠(sodium carboxymethylcellulose,CMC)、甘油制备的基础膜液中,制备成蓝色素膜;采用响应面优化成膜工艺;对膜的色素保留率、机械性能、透水性、抗氧化活性及抗油脂光氧化性等进行测定。结果色素添加浓度在0.02%~0.04%时,色素在膜中分布均匀,浓度增加到0.08%时,色素分布不均匀、有聚集现象;随着蓝色素添加量增大,膜的抗拉力强度增强,伸长率有所下降;最佳的成膜工艺是明胶2.474 g、CMC 1.125 g、甘油1.158 g、蓝色素0.03%;正常光照下膜的色素保留率可达90%以上,加速光照下膜的色素保留率可维持在80%以上;蓝色膜的自由基清除率随色素添加量的增加而增强,当添加量为0.06%时,1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基和2,2’-联氮-二(3-乙基-苯并噻唑啉-6-磺酸)二铵盐[2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)ammonium salt,ABTS]阳离子自由基的清除率分别为42.3%和32.4%;与无色素膜相比,蓝色素膜能使橄榄油的过氧化值(peroxide value,POV)降低45.7%。结论该蓝色膜有较好色素保留率、机械性能,同时具备抗氧化活性和抗光氧化性,本研究可为开发同时具备减缓油脂自动氧化和光氧化的可降解包装膜奠定了理论基础。

大庆油田二类B油层聚驱剖面动用规律及其改善

大庆油田聚合物驱应用规模不断扩大,开发对象转向性质较差的二类B油层,现有聚合物与油层适应性不强,剖面动用规律不明确,不同地区聚驱开发效果差异较大。针对上述问题,应用矿场剖面数据统计和室内实验分析,研究了二类B油层剖面动用规律和剖面改善方法。结果表明:从吸水层动用情况来看,喇嘛甸地区由于发育厚层河道砂,油层物性好,油层有效厚度动用比例最高,油层以多次动用为主,突进层多,相对吸液量高;萨中和萨南地区河道砂发育规模小,薄砂层较多,物性差,有效厚度动用比例较低,但聚驱后,有效厚度动用比例相比水驱分别增大了12.5%和15.4%,渗透率为100~300 mD的储集层吸入剖面改善明显;从未吸水层动用来看,二类B油层纵向非均质性强,导致层间有效厚度未动用比例较高,剖面改善应以均衡层间动用为主;抗盐聚合物高、低质量浓度交替注入可延缓含水率上升时间,增加低渗透层吸液量,聚驱采出程度提高显著。在喇嘛甸北北块A区开展了DS1200抗盐聚合物和高、低质量浓度交替注入试验,降水增油效果好,可为大庆油田二类B油层聚驱剖面改善提供技术指导。

国医大师许润三用抵当汤加减治疗瘀血型痛经之经验

国医大师许润三从医70余年,传承仲景学术思想,善用经方治疗各种妇科经带胎产杂等疾病,疗效显著。抵当汤出自《伤寒杂病论》,临床被用来治疗诸多血证,在妇科应用也较为广泛,但因抵当汤过于峻猛,被视为是一首破气血、伤正气的“虎狼之方”,故不敢应用,加之抵当汤中的水蛭是有毒之品,妇科应用更是审慎。国医大师许润三秉承仲景的辨证论治精神,将抵挡汤加减广泛用于治疗各种瘀血重症所致的痛经,疗效颇佳。

材料腐蚀与防护实验教学案例设计

针对材料类学生教学需求,以科研项目为牵引,设计了稀土合金化增强耐候钢表面锈层保护性能的实验教学案例。该实验案例以海洋大气环境下耐候钢耐蚀性能亟待提高这一实际工程问题为切入点,通过现场大气曝露腐蚀实验、实验室模拟加速腐蚀实验来评价耐候钢的耐腐蚀能力。通过扫描电镜、X射线衍射分析等物理方法和极化曲线等电化学方法,研究分析了稀土耐候钢在近海大气环境下表面锈层的形貌、物相组成、合金元素分布及其电化学腐蚀行为。利用综合实验结果分析了特定腐蚀环境下稀土耐候钢的耐蚀性能和耐蚀机理。该实验教学案例以“问题提出-材料制备-腐蚀行为分析-耐蚀性能评价”为主线,综合性强,涉及材料合金成分设计、电化学腐蚀机理、表征技术、电化学分析等众多知识点,在一定程度上实现了专业知识的系统化和一体化,对学生创新意识和研究能力的培养具有很好的推动作用。

用于特殊环境的薄膜应变计的制备与表征

使用磁控溅射制备了卡玛合金薄膜应变计,研究了退火温度对薄膜微观结构的影响,测试了薄膜的电学性能以及压阻响应特性,并进行了环境实验。结果表明,随着退火温度升高,薄膜的电阻率逐渐下降,电阻温度系数则逐渐升高,在室温下有最小的电阻温度系数(TCR),约为59.9×10^(-6)/℃,经过200℃退火处理的薄膜应变计的应变灵敏度系数(GF)为2.2,TCR为64.4×10^(-6)/℃。经历温湿循环、盐雾、霉菌试验后,薄膜的压阻特性变化不大,能耐受海洋特殊环境。

碳钢表面超疏水镀层的制备综合实验设计

结合教师科研成果,设计了本科教学碳钢表面超疏水镀层的制备综合实验,具体方法是采用电沉积方法在碳钢表面制备镍镀层,再以低表面能物质修饰,制备具有超疏水特性的表面并研究其耐腐蚀性能。该实验方法简单,综合性强,通过实验使学生进一步理解超疏水表面的构建原理、制备方法、性能表征及应用前景,有效提升学生动手能力,培养学生的创新能力和科学素养。

钢-PVA混杂纤维高性能混凝土抗渗性能试验研究

为探究钢纤维掺量、聚乙烯醇(PVA)纤维掺量和矿粉掺量对钢-PVA混杂纤维高性能混凝土(HFHPC)抗渗性能的影响,本文开展了钢-PVA HFHPC抗渗性能试验,并对试验结果进行了极差分析、方差分析和回归分析。结果表明:对HFHPC抗渗性能的影响程度从高到低依次为钢纤维、矿粉和PVA纤维。在试验水平范围内,得出混凝土试件抗渗性能最佳水平组合:钢纤维体积掺量1.0%、PVA纤维体积掺量0.7%、矿粉质量取代率20%。当钢纤维掺量超1.0%时,HFHPC抗渗性能略有下降,但仍高于基准素混凝土。最后采用多元回归分析,建立了HFHPC渗透系数与钢纤维、PVA纤维和矿粉的预测模型。

改变车身造型的气动阻力与分轴升力多目标优化

针对汽车分轴升力与阻力无法综合改善的问题,提出一种造型优化方案。以某SUV为研究对象,建立SUV流场仿真模型并分析外流场气动特性,确定车身需要优化的部位,通过风洞试验验证流场仿真结果的准确性。采用均匀拉丁超立方对造型取样并进行外流场数值仿真计算,通过克里金法建立造型参数与气动系数的对应关系,使用遗传算法生成Pareto前沿解。最终提出3种优化方案综合改善阻力系数和前后轴升力系数,分别使前轴升力系数达到最负值,阻力系数降低2.7%。

全民族抗战胜利的法宝:统一战线——基于新四军统战工作的历史考察

作为华中抗战重要组成部分的苏北抗日根据地抗日民族统一战线工作,是在中共中央华中局及新四军新军部的全面领导下开展的,在华中工作的新四军领导人刘少奇、陈毅等高度关注并率先垂范,通过全方位与国民党地方实力派和广大爱国开明士绅包括社会各界知识分子展开多层次接触,积极聚拢各方爱国人士,团结一切可以团结的力量投身于全民族抗战之中,对根据地的巩固发展和抗战最终胜利起到了重要的推动作用。新四军统战工作的经验在全国范围内都具有启迪与示范意义,至今仍值得新时代共产党人学习和发扬。

滩涂土壤离散元接触模型优化与现场铲削试验

为解决现有离散元接触模型对滩涂土壤特性表征准确性差的问题,该研究基于离散元仿真软件EDEM的API二次开发功能,以Hertz-Mindlin接触模型为基础,通过增加塑性、粘附特征并更改切向滑动摩擦力,得到优化后的高湿黏弹塑性(moist elasto-plastic adhesion,MEPA)模型。通过模拟活塞拔出试验,结合Plackett-Burman试验筛选出影响标定指标的显著参数,完成接触模型参数标定。搭建了铲削试验平台进行现场铲削试验,对比分析了MEPA模型、JKR模型、EEPA模型以及Bonding模型的土壤特性表征效果。试验结果表明,在铲削阻力方面,MEPA模型较JKR模型、EEPA模型和Bonding模型的仿真精度分别提升约65.957%、74.206%和59.326%;相较于现场试验结果,MEPA模型的堆积厚度与侧边距相对误差分别为5.598%和6.362%,两者均保持在10%以内,能够较好地模拟滩涂土壤,对滩涂工作装置的工况模拟和优化设计具有重要意义。