Sedimentary characteristics and internal architecture of a river-dominated delta controlled by autogenic process:implications from a flume tank experiment

Autogenic processes are widely found in various sedimentary systems and they play an important role in the depositional evolution and corresponding sedimentary architecture.However,autogenic processes are often affected by changing allogenic factors and are difficult to be identified and analyzed from modern and ancient records.Through the flume tank experiment under constant boundary conditions,the depositional process,evolution principles,and the sedimentary architecture of a river-dominated delta was presented,and a corresponding sedimentary architecture model was constructed.The evolution of river-dominated delta controlled only by autogenic process is obviously periodic,and each autogenic cycle can be divided into an initial progradational stage,a middle retrogratational stage,and a late aggradational–progradational stage.In the initial progradational stage,one feeder channel incised into the delta plain,mouth bar(s)was formed in front of the channel mouth,and small-scale crevasse splays were formed on the delta plain.In the middle retrogradational stage,the feeder channel was blocked by the mouth bar(s)which grew out of water at the end of the initial stage,and a set of large-scale distributary splay complexes were formed on the delta plain.These distributary splay complexes were retrogradationally overlapped due to the continuous migration of the bifurcation point of the feeder channel.In the late aggradational–progradational stage,the feeder channel branched into several radial distributary channels,overlapped distributary channels were formed on the delta plain,and terminal lobe complexes were formed at the end of distributary channels.The three sedimentary layers formed in the three stages constituted an autogenic succession.The experimental delta consisted of six autogenic depositional successions.Dynamic allocation of accommodation space and the following adaptive sediments filling were the two main driving factors of the autogenic evolution of deltas.

Water-Tank Experiment on the Thermal Circulation Induced by the Bottom Heating in an Asymmetric Valley

Water tank experiments were carried out to investigate the thermal convection due to the bottom heating in an asymmetrical valley under neutral and stably stratified approach flows with the Particle Image Velometry (PIV) visualization technique. In the neutral stratification approach flow, the ascending draft induced by bottom heating is mainly located in the center of the valley in calm ambient wind. However, with ambient wind flow, the thermal convection is shifted leeward, and the descending draft is located on the leeward side of the valley, while the ascending draft is located on the windward side. The descending draft is minorly turbulent and organized, while the ascending draft is highly turbulent. With the increase of the towing speed, the descending and ascending drafts induced by the mechanical elevation begin to play a more dominant role in the valley flow, while the role of the thermal convection in the valley airflow becomes limited. In the stable stratification approach flow, the thermal convection is limited by the stable stratification and no distinct circulation is formed in calm ambient wind. With ambient wind, agravity wave appears in the upper layer in the valley. With the increase of the ambient wind speed, a gravity wave plays an important role in the valley flow, and the location and intensity of the thermal convection are also modulated by the gravity internal waves. The thermal convection has difficulty penetrating the upper stable layer. Its exchange is limited between the air in the upper layer and that in the lower layer in the valley, and it is adverse to the diffusion of pollutants in the valley.

Hydrodynamic Characteristics of the Biplane-Type Otter Board with the Canvas Through Flume−Tank Experiment

Hydrodynamic characteristics of a biplane-type otter board,equipped with nylon canvas of 2 mm in thickness was investigated through flume-tank experiment in this study.A series of predesigned structures with different gap-chord ratios G/c(0.75,0.90,1.05),stagger anglesθ(30°,45°,60°),and proportions of flexible area relative to the whole wing areaƒr(0,55%,65%,75%),at an aspect ratio of 2.0 and a camber ratio of 15%,were experimentally carried out.The results showed the solution referring to the usage of flexible canvas replacing part of rigid structure for the biplane-type otter board was efficient for the trawling in the middle or shallow water area.The improvement of lift and stability for the biplane-type otter board was concluded,and drag of the structure was reduced by 1.9%atƒr=55%.In addition,the coefficient of variation of the lift and drag coefficient at different current velocities were 2.69%and 2.28%,respectively,which was smaller than those at relatively large proportion of the flexible area.Compared with the other tested structures,the frame-type flexible structure with the gap-chord ratio of 0.9 and a stagger angle of 45°and the proportion of the flexible area of 55%,performed best,and its drag was reduced by 5.72%and lift increased by 4.8%,compared with the rigid biplane-type otter board at the angles of attack from 18°to 28°.

Effects of Perforated Baffle on Reducing Sloshing in Rectangular Tank:Experimental and Numerical Study

A liquid sloshing experimental rig driven by a wave-maker is designed and built to study liquid sloshing problems in a rectangular liquid tank with perforated baffle. A series of experiments are conducted in this experimental rig to estimate the free surface fluctuation and pressure distribution by changing external excitation frequency of the shaking table. An in-house CFD code is also used in this study to simulate the liquid sloshing in three-dimensional （3D） rectangular tank with perforated baffle. Good agreements of free surface elevation and pressure between the numerical results and the experimental data are obtained and presented. Spectral analysis of the time history of free surface elevation is conducted by using the fast Fourier transformation.

Migration of Infiltrated NH_4 and NO_3 in a Soil and Groundwater System Simulated by a Soil Tank

The infiltration of water contaminants into soil and groundwater systems can greatly affect the quality of groundwater. A laboratory-designed large soil tank with periodic and continuous infiltration models, respectively, was used to simulate the migration of the contaminants NH4 and NO3 in a soil and groundwater system, including unsaturated and saturated zones. The unsaturated soil zone had a significant effect on removing NH4 and NO3 infiltrated from the surface water. The patterns of breakthrough curves of NH4 and NO3 in the unsaturated zone were related to the infiltration time. A short infiltration time resulted in a single sharp peak in the breakthrough curve, while a long infiltration time led to a plateau curve. When NH4 and NO3 migrated from the unsaturated zone to the saturated zone, an interracial retardation was formed, resulting in an increased contaminant concentration on the interface. Under the influence of horizontal groundwater movement, the infiltrated contaminants formed a contamination-prone area downstream. As the contaminants migrated downstream, their concentrations were significantly reduced. Under the same infiltration concentration, the concentration of NO3 was greater than that of NH4 at every corresponding cross-section in the soil and groundwater tank, suggesting that the removal efficiency of NH4 was greater than that of NO3 in the soil and groundwater system.

Numerical and Experimental Studies on Flow and Pollutant Dispersion in Urban Street Canyons

In this study numerical simulations and water tank experiments were used to investigate the flow and pollutant dispersion in an urban street canyon. Two types of canyon geometry were tested. The studies indicate that in a step-up notch canyon （higher buildings on the downstream side of the canyon）, the height and shape of the upstream lower buildings plays an important role in flow pattern and pollutant dispersion, while in a step-down notch canyon （lower buildings on the downstream side）, the downstream lower buildings have little influence. The studies also show that the substitution of tall towers for parailelepiped buildings on one side of the canyon may enhance the street ventilation and decrease the pollutant concentration emitted by motor vehicles.

Nepheloid layer generation by gas eruption:unexpected experimental results

Knowledge of nepheloid layers is important to improve the understanding of physical,geological,and sedimentary processes from continental shelf to abyssal environments.We had not tried to study the nepheloid layers in a hydrate-associated tank until unexpected results occurred.Tank experimental results show that gas eruptions triggered intermediate nepheloid layers.Thus,we proposed a new mechanism of intermediate nepheloid layer generation by eruptions.The intermediate nepheloid layers were generated in uniform-density fluid,which indicated that stratified fluid is not a necessary condition for intermediate nepheloid layers.Sufficient space for advection and an oblique slope for detachment are the key ingredients for intermediate nepheloid layer generation by eruptions.Our experiments also offer a new experimental evidence for bottom nepheloid layer generation by earthquakes.Given the scale effects of laboratory experiment,it is important to determine whether submarine volcanic eruption or hydrate-associated venting causes intermediate nepheloid layer in the nature.

Research of refrigeration system for a new type of constant temperature hydraulic tank

Different from the traditional hydraulic oil cooling method,a new type of constant temperature oil tank cooling system based on semiconductor refrigeration technology is designed. This paper studies the principle of semiconductor refrigeration and establishes a heat transfer model. Semiconductor cooler on piping refrigeration is simulated,and influence of the parameters on the outlet temperature,such as pipe pressure difference of inlet and outlet,pipe length,pipe radius,are gotten,and then hydraulic tank semiconductor refrigeration system is proposed. The semiconductor refrigeration system can control temperature at 37 ± 1°C.

Weld Models Incorporating the HAZ Phase Transformation Effects, Comparison between Experimental and Numerical Results

Numerical simulations of a representative test of welding process are presented in this paper. A French vessel steel, which involves metallurgical phase transformations in solid state is considered in this work. The aim is to validate the thermal-metallurgical-mechanical models taking into account the metallurgical transformations in the finite element codes Sysweld (Framasoft) and Code Aster (EDF). The test is performed on a thin disc submitted to a thermal cycle loading by means of a CO2 laser beam, which leads to metallurgical phase transformations. The thermal, metallurgical and mechanical numerical results have been compared to the experimental results (temperatures, sizes of transformed zones, displacements and residual stresses and strains). The main objective of the numerical analysis is to have some results which enable to give some indications on the ability of the numerical codes to describe the observed phenomena. For that, it is necessary to simulate accurately the thermo-metallurgical history. The comparison of experimental results with the numerical ones leads to some interesting orientations related to the capacities of the considered models to describe the observed phenomena.

基于正交实验法的储罐泄漏对邻近建筑影响研究

为准确评估气相危险化学品从储罐中意外泄漏对周边环境的影响,以邻近建筑为研究对象,结合正交实验法,针对不同的考察指标,对影响危险气体在周边区域扩散的4个关键因素进行分析。研究结果表明:泄漏位置仅对建筑迎风面危险气体极值体积分数有较为明显的影响,不同泄漏位置造成的差异能达到23.2%。建筑密度的增加导致建筑区域面平均体积分数增加30%以上,而建筑区域危险气体极值体积分数分别降低了9.4%和30.4%。建筑与储罐组间距和建筑密度对于邻近建筑的影响强度(以极差来评价),是泄漏位置和气体种类的1.5~10倍。研究结果可为化工园区安全设计、合理规避事故风险提供参考。

某乘用车燃油箱强度仿真及试验研究

针对乘用车燃油箱这一重要的安全部件,在其前期设计阶段进行考虑流固耦合的有限元分析发现,前部和后部跌落存在应变超标现象。对其风险部位进行结构改进,强度仿真显示,等效塑性应变最大值相比改进前分别减少44.7%和33.3%,跌落试验显示均无泄漏和破裂发生,满足设计要求。结果表明,基于有限元分析的仿真和试验为燃油箱的开发提供了科学依据,可有效提升产品开发效率并降低试验成本。

铁路罐车封头冷冲压成形试验研究

通过对封头成形工艺的对比分析,根据铁路罐车封头需求量大、成形质量要求高的特点,制定了厚壁封头冷冲压成形工艺。通过试验研究的方法对EHA 3000×22(19)-Q345R GB/T 25198厚板冷冲压封头成形前、后的外形尺寸、壁厚、力学性能等变化规律进行了分析研究。对封头成形前后的各项试验数据进行对比分析,掌握了厚壁封头冷冲压的成形规律;通过5组封头热处理试验掌握了热处理对冷成形封头性能的影响规律,提高了冷冲压封头的性能,确保了冷冲压封头的成形质量,保证了铁路罐车的运行安全。

极坐标-直角坐标下水下目标跟踪算法及试验研究(英文)

在实际水下目标跟踪系统中,由声纳获得的速度量测是一个相对径向速度,并且量测噪声是非白的,为此提出了基于扩展量测和扩展状态的混合坐标系下水下目标跟踪算法。该方法把径向速度量测引入观测模型,提高了目标的状态估计精度和收敛时间;引入了扩充向量,克服了实际水下目标观测噪声非白的影响。提出了水下多目标跟踪水池试验方法。该方法应用静态长线阵和多目标信号源在水池实现了多目标和跟踪体之间的相对运动的模拟。水池试验结果表明所提出的方法性能明显优于基于量测转换跟踪方法(如MC方法),具有重大工程应用价值。

基于数值波浪水槽的港航专业实验教学改革与实践

采用MIKE21软件构建数值波浪水槽,其与物理波浪水槽相结合应用于港航专业的实验教学。实践证明,两种方式优势互补,为学生提供了更生动多元的实验平台,打破了时间空间壁垒,充分调动了学生创新探索的积极性和自主学习的热情,为培养港航专业卓越工程师人才起到了积极推动的作用。

隔板装置对恒温水箱的性能影响分析(2)试验验证

试验验证经过数值优化设计的恒温水箱。试验结果表明,该水箱中流体在3个区域外部正向循环,内部反向循环,流体温度渐变收敛,至冷媒水和冷却水取水口处温度恒定,可以保证水冷冷水机组性能测试装置的进水温度工况条件。通过贝塞尔公式分析试验与模拟数据的标准残差和试验数据的标准离差之间的数值关系,表明所建立的恒温水箱模型准确性高,能够充分反映水箱内的实际换热过程,并可为相似用途的恒温水箱内部隔板设计提供参考。

搅拌反应器中液相混合时间研究进展

搅拌反应器是一种在化工、医药、能源和废水处理等领域应用比较广泛的设备。其中混合时间是表征搅拌反应器内物料混合状况的一个重要参数。本文从实验测量方法和数值模拟两个方面综述了近50年来对混合时间的研究,并展望了未来混合时间测量方法和数值计算的发展方向。

基于试验模态分析的原油储罐损伤识别研究

基于试验模态分析的基本原理,对立式拱顶钢制原油储罐模型进行应变模态试验,考察了模态参数对原油储罐模型损伤程度和损伤位置的识别能力。试验分析表明,罐体结构在损伤位置相同的情况下,损伤程度越大,频率的衰减增大,但相对变化率的变化规律不甚明显;位移振型不能给出损伤的位置信息,振型差曲线可以识别出罐体损伤位置;随着模型内充水高度上升,结构频率呈下降趋势,反映了附加质量和附加阻尼的作用;罐内液体存在对损伤位置识别影响不大。

16MnR钢在高温(火灾)下的力学性能试验研究

考虑到我国液化石油气储罐所使用的材料多为 16MnR钢 ,对该钢种在高温下的力学性能进行了试验研究 ,得出了 16MnR钢在温度≤ 6 0 0℃时的各项力学性能指标 ,包括应力 应变曲线、屈服强度、极限强度、伸长率、弹性模量随温度变化的规律 ,并利用其对储罐的失效压力进行了分析研究。试验结果表明 ,16MnR钢在高温下强度、伸长率等明显下降 ,6 0 0℃时其屈服强度、极限强度、弹性模量等仅为常温下的 2 0 %～ 30 % ,伸长率为 4 3% ,此时液化石油气储罐的爆破压力仅为常温下的 。

A Comparative Study on Hydrodynamic Performance of Double Deflector Rectangular Cambered Otter Board

In the present work,the hydrodynamic performance of the double deflector rectangular cambered otter board was studied using wind tunnel experiment,flume tank experiment and numerical simulation.Results showed that the otter board had a good hydrodynamic performance with the maximum lift-to-drag ratio(K_(MAX) = 3.70).The flow separation occurred when the angle of attack(AOA) was at 45?,which revealed that the double deflector structure of the otter board can delay the flow separation.Numerical simulation results showed a good agreement with experiment ones,and could predict the critical AOA,which showed that it can be used to study the hydrodynamic performance of the otter board with the advantage of flow visualization.However,the drag coefficient in flume tank was much higher than that in wind tunnel,which resulted in a lower lift-to-drag ratio.These may be due to different fluid media between flume tank and wind tunnel,which result in the big difference of the vortexes around the otter board.Given the otter boards are operated in water,it was suggested to apply both flume tank experiment and numerical simulation to study the hydrodynamic performance of otter board.

三容实验系统内模控制研究

针对三容实验系统液位的控制,介绍了三容液位过程内模控制系统的设计和实现。提出了一种内模PID(Internal Model Control-PID,IMC-PID)控制方法。建立了被控对象的数学模型,对数学模型进行理论推导,建立系统的状态矩阵方程,对模型进行近似处理。将三阶系统等效为一阶系统。为了使系统可实现,设计控制器时增加了一个一阶滤波器。并依据内模控制原理设计控制器,并且在内模控制的理论基础上设计了内模PID控制器,在Matlab/Simulink中分别搭建了此两个系统的数学模型,并进行仿真实验。对内模控制(IMC)和内模PID(IMC-PID)两种控制器控制结果进行对比分析。实验结果表明,内模控制器结构简单,可调参数少。内模PID参数调整方便,能有效地改善系统的性能。