Numerical investigation of water-entry of flatted-bottom seafloor mining tool in ocean waves

A numerical wave load model based on two-phase(water-air) Reynolds-Averaged Navier Stokes(RANS) type equations is used to evaluate hydrodynamic forces exerted on flatted-bottom seafloor mining tool during its entering ocean waves of deploying process.The discretization of the RANS equations is achieved by a finite volume approach(FV).The volume of fluid method(VOF) is employed to track the complicated free surface.A numerical wave tank is built to generate the ocean waves which are suitable for deploying seafloor mining tool.A typical deploying condition is employed to reflect the process of flatted-bottom body impacting with waves,and the pressure distribution of bottom is also presented.Four different lowering velocities are applied to obtain the time histories of maximum pressure of bottom,and it can be concluded that the pressure coefficient decreases with water velocity increasing,which is similar with ordinary water entry case.The numerical results clearly demonstrate the characteristics of flatted-bottom body entering ocean waves.

Nonlinear Simulation of Focused Wave Group Action on a Truncated Surface-Piercing Structure

In this study, we numerically investigated the nonlinear focused wave group action on a truncated surface-piercing structure, and developed a two-dimensional fully nonlinear numerical tank using the higher-order boundary element method. We determined the amplitude of the wave components of the focused wave group based on the JONSWAP wave spectrum. We discuss the effects of the presence of a surface-piercing structure on the characteristics of the focused wave group and find that the location of the structure does not evidently change the focal location or focal time of the focused wave group. The largest amplitudes of the run-up and horizontal force on the structure occur when the front surface of the structure is at the focal location. The critical draught and breadth of the structure occur when the wave run-up reaches its maximum along the structure.

Numerical Analysis on Motion of Multi-column Tension-Leg-Type Floating Wind Turbine Basement

The offshore wind energy presents a good solution for the green energy demand.The floating offshore wind turbine(FOWT)is one of the most potential choices of the basement construction for offshore wind turbines in deep water.Hydrodynamic performance of multi-column tension-leg-type floating wind turbine is investigated numerically,particularly at its motion responses.Based on the Navier-Stokes equations and the volume of fluid method,a numerical wave tank(NWT)is established to simulate the floating structure system.The analytical relaxation method is adopted to generate regular waves.Dynamic mesh method is used to calculate the motion of the floating body.Hydrostatic decay of motion and hydrodynamic forces in the regular wave are provided.The computation results agree with the experimental data available.Numerical results show that the wave force on the lower pontoon of the system is the greatest while that on the center column is the smallest.Detailed information about the changes of the wave forces on different elements of the floating system is discussed.

常压罐车罐体检验机构资质管理与技术要求研究

我国常压罐车罐体的第三方检验分为出厂检验和定期检验,常压罐车罐体检验机构管理和检验技术要求存在较多问题。通过分析我国常压罐车罐体检验机构资质要求和技术要求,提出了相应的对策建议,可为常压罐车罐体的生产、检验、认可、监管提供参考。

双浮体直驱波浪发电装置建模分析与基于模型预测控制的能量提取算法研究

基于振荡浮体结构的直驱波浪发电装置具有损耗低、控制灵活等优点,近年来,逐渐成为波浪发电领域的研究热点。双浮体直驱波浪发电装置不需要海上固定平台,能够通过锚系结构在海水中工作,是一种工程可行的直驱波浪发电方案,但其动力学模型更为复杂,相关控制算法缺少实际装置测试。该文通过等效电路的方法对双浮体装置进行建模分析,指出采用张力锚结构可将双浮体装置等效为单浮体装置进行分析,简化控制器的分析与设计,从而建立基于模型预测控制的高效波浪能提取问题。提出一种结合波浪激励力辨识、预测与快速模型预测求解的控制算法,并且设计了双浮体直驱波浪发电装置,在不同波浪条件下进行了相关实验测试。实验结果表明,所提控制算法能够在有效降低运算复杂度的前提下提高装置的波浪能提取效率。

大坡度低矮巷道掘进机关键技术探讨

介绍了煤矿巷道机械化以来掘进机在大坡度低矮巷道中应用所面临的一些问题,对煤矿大坡度和低矮巷道条件下掘进机设计的关键问题进行了阐述,针对问题提出了解决方案,提出了掘进机在大坡度低矮巷道中应用研究的方向。

3t电弧炉炉膛扩容改造的实践

作者针对公司老龄3 t电弧炉冶炼钢水吨位小、单耗高的实际情况,通过对炉壳出钢口进行适度的改造,进而实现了炉膛的扩容和炉料的扩装,并通过加长出钢槽、增大出钢槽倾角措施,解决了由于出钢口提高而带来的钢水包吊车钢丝绳与电弧炉电极架相互碰撞问题,炉膛扩容改造后从原额定容量3 t扩容到了5 t,显著地提高了钢水冶炼效率,为老龄3 t电弧炉冶炼钢水节能降耗、增产增效提供了技术保障。

强化处理对GIS罐体焊缝组织和性能的影响

气体绝缘金属密封组合电器(GIS)上使用的互感器罐体为2A12铝合金材质,为了分析2A12铝合金焊接工艺并提高罐体焊缝质量,对2A12铝合金进行钨极氩弧焊(TIG)焊接工艺试验,并在不同强化处理条件下对焊缝的微观组织及性能进行了研究。通过对比试验发现,不同的强化处理方式下,焊缝性能不同,采用退火+固溶+分级时效强化处理的焊缝性能最好,而退火+单级时效强化处理后的焊缝性能最差。

卧式罐容量测量方法研究

本文介绍了一种快速测量卧式罐容量的方法,用以解决传统容量比较法和几何测量法在检测时存在的问题。该方法通过使用高精度电子秤和双路并行等手段,实现了对检测介质的快速称重和对卧式罐内液位的自动读取。相较于传统方法,该方法显著提高了检测效率、降低了劳动强度,并在使用场景上具备灵活性,适用于各种环境条件。该方法具有检测效率高、对罐体变形容忍度高等特点,可为工业生产提供更为便捷、高效、可靠的卧式罐容量测量手段,为该领域带来了创新性的解决方案。

Impact of combined systolic blood pressure and body mass index on the risk of new-onset atrial fibrillation

Objective To observe the impact of combined systolic blood pressure and body mass index(BMI)on the risk of new-onset atrial fibrillation.Methods The participants who participated the health examination between July 2006 and October 2007 at Kailuan medical group and had no history of atrial fibrillation were selected as the observation cohort.The second,the third and

堰塞体溃决离心模型试验供水系统关键技术研究

堰塞体溃决洪水洪峰流量及洪水时程曲线特征的预测是堰塞湖应急抢险及下游风险控制方案制订的重要依据。堰塞体溃决的离心模型试验,在研究堰塞体溃决机理、溃决过程及溃决洪水的历时曲线特征方面独具优势,但离心模型试验供水系统的设计,涉及到从外部静止状态到高速旋转状态的模型中连续供水,同时还要保证堰塞体溃决过程中上游水位为设定的常水头,是堰塞体溃决离心模型试验中的关键性的一大难题。本文围绕以上难题,设计了一种环形水箱以解决从静态到动态模型的连续供水问题,通过理论分析,确定了环形水箱中可提前注入的最大水量。另外在试验箱设置了竖井式溢流口,可以排出高出设定常水头的水体,保证了上游水位的稳定。通过以上设计有效地解决了供水系统中的关键难题,并在后续堰塞体溃决离心模型试验中得到了验证。

炼钢厂煤气烘烤器危险因素分析及管控对策

针对近年来互联网发布的各类行业发生的烟气脱硫塔设施火灾爆炸事故的发生原因与发生环节进行归类和分析,并对某钢铁企业焦化厂检维修动火作业发生的脱硫塔火灾爆炸事故进行深入剖析,提出烟气脱硫塔设施火灾爆炸事故风险管控对策,可为相关企业减少类似事故发生提供指导。

WAVE-BODY INTERACTIONS FOR A SURFACE-PIERCING BODY IN WATER OF FINITE DEPTH

Nonlinear wave-body interactions for a stationary surface-piercing body in water of finite depth with fiat and sloping bottoms are simulated in a two-dimensional numerical wave tank, which is constructed mainly based on the spatially averaged Navier-Stokes equations with the k- ε model for simulating the turbulence. The equations are discretized based on the finite volume method and the scheme of the pressure implicit splitting of operators is employed to solve the Navier-Stokes equations. By using the force time histories, the mean and higher-harmonic force components are calculated. The computational results are shown to be in good agreement with experimental and numerical results of other researchers. Then, the horizontal force, the vertical force and the moment on the surface-piercing body under nonlinear regular waves with flat and sloping bottoms are obtained. The results indicate that the bottom topographies have a significant influence on the wave loads on the surface-piercing body.

基于无线体域网的运动数据采集仪设计

本文针对传感设备在无线体域网中的实际应用,设计了以STM32F103C8T6为核心处理器的运动数据采集仪。该采集仪能实时捕捉用户心率、体温、步数等健康数据,并通过LoRa通讯实现数据上传,具备数据显示、数据存储、历史数据访问等功能。此外,针对ECG信号中存在的基线漂移问题,本文采用中值滤波算法进行处理,该方法在保持ECG信号特征的前提下,有效去除了基线漂移噪声。经测试,本运动数据采集仪在实际应用中运行稳定,各项性能均满足指标要求。

规则波条件下的多液舱浮体动力响应特性研究

为了研究多液舱浮体的动力响应特性,基于势流理论进行多液舱浮体动力响应的频域分析。首先考虑不同的网格尺寸开展网格敏感性分析,随后针对规则波中单液舱浮体开展建模计算并与相关试验结果进行对比验证。最后分析多液舱浮体的动力响应特性,并探讨载液量及载液类型对浮体动力响应的影响。研究发现:液舱对浮体横荡的影响较小,对横摇的影响较大,垂荡响应与全系统自重有关;横摇响应曲线的峰值大小及峰值数量与液舱的载液类型存在一定关联。

Effects of clozapine and haloperidol on body weight,neuropeptide Y and leptin in patients with schizophrenia

Objective To investigate the changes of neuropeptide Y(NPY) ,leptin,body weight and their relationship in schizophrenics with clozapine and haloperidol treatment. Methods Thirty schizophrenic patients

浅析常压罐车金属常压罐体定期检验中发现的问题及处理办法

随着社会经济迅速发展,工业生产及民用中普遍使用的道路运输液体危险货物罐式车辆(以下简称“常压罐车”)市场占有率逐年递增,与此同时,大量不符合国家标准要求的常压罐车“带病运行”,其安全性能越来越受到关注。本文从常压罐车金属常压罐体设计、制造、检验及运营监管等方面出发,简要阐述了其在检验时发现的问题并进行原因分析,提出处理办法和建议[1]。

基于有限元的矿用燃油箱托架结构优化设计

汽车燃油箱托架是汽车燃油供给系统中的关键部件,油箱托架承受着燃油箱本体以及燃料的冲击,其常见的受力形式多为受到来自路面的冲击载荷,在其作用下易发生失效。本文主要针对某特种矿用宽体车大容积燃油箱的需求,提出与其所匹配的油箱托架的强度(超强承载能力、抗外界冲击能力等)设计是否满足要求。通过利用CATIA进行针对性特殊设计,然后建立燃油箱托架有限元模型。最后,在不同的方案以及工况下,分别赋予不同的材料属性并利用Optistruct进行求解及强度对比分析,结果表明:在转向、冲击和制动的几种边界条件下,油箱托架应力最大平均值均在材料最大许用应力范围内,安全系数得到提升,符合设计要求,避免了应力集中及早期失效现象。

基于点云聚簇的铁路罐车罐体外部孤点自动去除算法研究

采用三维激光扫描法检定铁路罐车罐体时,扫描形成的容积检定点云中可能存在罐体外部孤点,这会影响罐车容积检定的准确性。因此,提出基于点云聚簇的铁路罐车罐体外部孤点自动去除算法。在分析铁路罐车罐体外部孤点特征的基础上,介绍点云聚簇算法流程,阐述去除外部孤点的点云聚簇算法,以及点簇语义类别判定原则,实现铁路罐车容积检定过程中罐体外部孤点的自动去除。分别运用中值滤波器、欧式距离算法和点云聚簇算法,开展G11K,G60K和G70K罐车容积检定过程中原始点云的罐体外部孤点去除试验,并进行对比分析。分析结果表明,与中值滤波器、欧式距离算法相比,点云聚簇算法去除罐体外部孤点效果较好,可为铁路罐车容积检定提供更精确的数据。

考虑桩土-隔震层-罐体相互作用的隔震储罐地震响应分析

为了研究桩土、隔震层与罐体相互作用对15×104m3隔震储罐地震响应的影响,桩与隔震层采用弹簧-阻尼单元,罐体采用壳单元,流体采用势流体单元,基于ADINA建立数值仿真分析模型,在8度El Centro地震动激励下,应用Newmark数值积分方法进行地震响应分析。结果表明:隔震储罐基底剪力和基底弯矩相对于非隔震储罐明显降低,储罐罐壁加速度沿罐壁高度方向近乎平动,但对波高的控制效果不明显;除罐壁顶部外,动液压力明显降低;隔震后,罐壁有效应力和环向应力减震效应明显,对轴向应力和径向应力影响较小,建议从安全角度考虑,储罐非隔震设计时不考虑桩土作用,隔震设计时考虑桩土对罐体的影响。