Numerical Simulation of Residual Circulation due to Bottom Roughness Variability Under Tidal Flows in A Semi-Enclosed Bay

Nowadays there are some chronic serious environmental problems, such as eutrophication, blue tide and so on, in a complicated coastal zone or a semi-enclosed bay, because the water exchanges between an inner bay and an outer sea is weak compared with the supply of contaminant. Under this situation, a method to improve the water quality by 3-dimensional small unsymmetrical structures has been proposed by Komatsu et al. In this paper, several numerical simulations of the tidal current and concentration for various arrangements of bottom roughness in a semi-enclosed model bay are carfled out with a depth-averaged 2-D numerical model. The model is solved by the hybrid finite analytic method with nonstaggered grid. And the SIMPLES algorithm with Rhie and Chow＇ s momentum interpolation technique is used for the simulation. The effect of Komatsu＇ s method for water purification is examined by numerical simulation. The result of numerical experiment indicates that it is possible to generate a new tidal residual current and to activate a tidal exchange by bottom roughness arrangement only.

Influence of Reclamation Works on the Marine Environment in a Semi-Enclosed Bay

The flow and seawater exchange rates have been predicted using a two-dimensional numerical model and a Lagrangian method for a semi-enclosed shallow bay where reclaiming and dredging works are scheduled. The wind effect on the flow and material transport has been emphasized, and a thirty-year mean value of wind has been considered in the numerical simulation. As a whole, even after the reclaiming and dredging are conducted, the flow pattern looks similar to the original state. However, velocity variations up to 20% to 100% appear in the vicinity of the construction area. In the case of summcr wind forcing, the seawater exchange rate increases from 71.6% to 82.9% after the reclaiming and dredging, as indicated by a particle-tracking method. On the contrary, in the case of winter wind forcing, thc seawater cxchange rate appears to be 97.2% under natural conditions but decrcases slightly to 93.2% aftcr the rcclaiming and dredging. Thus, the wind forcing plays an important role in controlling the seawater exchangc rates. The seawater cxchange rate is further improved by 15% if the dredging is simultaneously carried out with the reclaiming. This suggests that the dredging can be an effective means to mitigate the variation of flow.

Semi-enclosed experimental system for coal spontaneous combustion for determining regional distribution of high-temperature zone of coal fire

Temperature variation and gas generation at diferent depths and positions in the coal combustion process were studied to determine the propagation and evolution of high temperature regions in the process of coal spontaneous combustion.This study selected coal samples from Mengcun,Shaanxi Province,People’s Republic of China,and developed a semi-enclosed experimental system(furnace)for simulating coal combustion.The thermal mass loss of coal samples under various heating rates(5,10,and 15℃/min)was analyzed through thermogravimetric analysis,and the dynamic characteristics of the coal samples were analyzed;the reliability of the semi-enclosed experimental system was verifed through the equal proportional method of fuzzy response.The results reveal that the high-temperature zone is distributed nonlinearly from the middle to the front end of the furnace,and the temperatures of points in this zone decreased gradually as the layer depth increased.The apparent activation energy of the coal samples during combustion frst increased and then decreased as the conversion degree increased.Furthermore,the proportion of mass loss and the mass loss rate in the coal samples observed in the thermogravimetric experiment is consistent with that observed in the frst and second stages of the experiment conducted using the semi-enclosed system.The research fndings can provide a theoretical basis for the prevention and control of hightemperature zones in coal combustion.

Investigation of wave characteristics in a semi-enclosed bay based on SWAN model validated with buoys and ADP-observed currents

In this study, the simulating waves nearshore (SWAN) model with a locally refined curvilinear grid system was constructed to simulate waves in Jervis Bay and the neighbouring ocean of Australia, with the aim of examining the wave characteristics in an area with special topography and practical importance. This model was verified by field observations from buoys and acoustic Doppler profilers (ADPs). The model precisions were validated for both wind-generated waves and open-ocean swells. We present an approach with which to convert ADP-observed current data from near the bottom into the significant wave height. Our approach is deduced from the Fourier transform technique and the linear wave theory. The results illustrate that the location of the bay entrance is important because it allows the swells in the dominant direction to propagate into the bay despite the narrowness of the bay entrance. The wave period T p is also strongly related to the wave direction in the semi-enclosed bay. The Tp is great enough along the entire propagating direction from the bay entrance to the top of the bay, and the largest Tp appears along the north-west coast, which is the end tip of the swells’ propagation.

Radial tidal current field in a semi-enclosed rectangular basin: formation and evolution

The radial tidal current field accounts for the formation of the radial sand ridges in the South Yellow Sea. Understanding the formation and evolution of this radial tidal current field is vital to assessing the morphodynamic features in the area. A semi-enclosed rectangular basin with and without a coastal barrier was schematized from the topography of the Bohai Sea and Yellow Sea. The 2D tidal current field in this basin was simulated using the DELFT3D-FLOW model. The concept of tidal wave refraction, which highlights the effect of the sloped or stepped submarine topography on the propagation of the tidal waves, was introduced to explain the formation of the radial tidal current field. Under the effect of tidal wave refraction, co-phase lines of the counterclockwise rotating tidal wave and incident tidal wave are transformed into clockwise and counterclockwise deflections, respectively, leading to the convergence and divergence of the flow field. Regardless of whether a coastal barrier exists or not, the outer radial tidal current field might emerge over certain topography. The responses of the radial tidal current field in this basin to the environmental variations such as coastline changes and bottom erosions were discussed. Results show that local protrusion near the focal point of the radial tidal current field will have limited effects on the location of the tidal system. However, a remarkable shift of the amphidromic point toward the entrance and central axis of this basin and a movement of the focal point of the radial tidal current field toward the entrance could be caused by the significant seaward coastline advance and submarine slope erosion.

Simulation Analysis of Electromechanical Coupling for Unmanned Aerial Vehicle Cabin Door System

In order to study the dynamic response of the unmanned aerial vehicle cabin door opening and closing system under impact load conditions, considering the flexible treatment of mechanical components, and the system’s motion with different stiffness of energy-absorbing components, a rigid-flexible coupling model of the cabin door actuation system was established in LMS. Virtual. Motion. In Amesim, a control model of the motor was created. Through the Motion-Amesim co-simulation module, the dynamic module of the system was combined with the motor control module to complete the electromechanical coupling simulation and analyze the results. .

Generation of a Controlled Polluted Atmosphere for Vehicles’ Cabins Air Quality Characterization

Air pollution induces significant health risks to individuals exposed to high levels of pollutants concentration. For ground vehicles, pollutants infiltrate the car cabin through the ventilation system, leading to potential health issues. To address this problem, a project was undertaken to develop a protocol for characterizing in-cabin air quality. The study involved a closed chamber (the bubble) where its internal multiphase flow has been optimized to create controlled polluted atmospheres. Experiments were conducted to optimize the positioning of the stirring fan and particle generation source, ensuring a homogeneous distribution of fine and ultrafine particles. This study demonstrated the feasibility of implementing a platform dedicated to characterizing the vehicles’ in-cabin air quality under controlled conditions. It allows a better understanding of the dynamics of particle infiltration and the establishment of an optimized protocol for simultaneous measurements of indoor and outdoor concentrations.

智能机舱验证平台设计与开发

智能机舱是近年来提出的概念,目前尚处于初级阶段,其功能,如数据采集、特征提取,以及故障诊断等的准确性尚缺乏规范性的验证手段。以某型内河船舶机舱动力系统为对象,基于NI LabVIEW软件平台和现场可编程门阵列硬件开发智能机舱验证平台,结合监测设备工作过程机理,按信号特征、通道,以及接口一致的原则,模拟输出柴油机、辅助发电机、齿轮箱和轴系等设备各类监测信号。通过开发的控制软件,可实现标准的、故障的和设备性能衰退的3类信号输出,为智能机舱系统数据采集、信号特征提取、监测诊断算法,以及健康状态评估算法的准确性和实时性提供验证平台。

高灵敏微波载荷卫星出舱电缆及舱体屏蔽的EMC设计

针对高灵敏微波载荷卫星对舱板电磁屏蔽效能的高需求与出舱电缆对舱体屏蔽效能巨大破坏性之间的矛盾,文章首先提出航天器理想舱板(无出舱电缆)的电磁屏蔽效能分析方法,给出提高对于1 GHz以上干扰电磁波屏蔽效能的设计原则;然后分析出舱电缆成为影响航天器外舱板对P波段(150 MHz~1 GHz)电磁波屏蔽效能主要因素的机理,给出干扰电流与干扰场强关系计算公式;最后给出出舱电缆及舱体屏蔽的电磁兼容(EMC)设计方法,提出用接地电阻测量法验证出舱电缆屏蔽皮接地的有效性,为总体总装EMC实施找到关键控制手段,并通过整星试验数据确认此方法能有效提升整星EMC试验效率。

一种虚拟试验架构下的舱段结构建模与承载破坏模拟技术

在一种面向产品的飞行器结构强度虚拟试验架构下,发展经典材料弹塑性损伤本构和通用有限元技术,并基于Abaqus内置Python软件开发虚拟试验插件工具,创建飞行器舱段结构人机交互虚拟试验平台,形成了对舱段结构承载破坏过程进行高逼真度模拟的虚拟试验能力。采取逐级验模的精度确认技术,开展从试棒到舱段壳体的虚/实试验对比,验证舱段结构虚拟试验的可行性,结果显示:虚拟试验能对舱段结构的承载破坏情况做高逼真度的模拟,对极限承载能力的预示精度达到4.6%。

基于支持向量机集成的船舶舱室温湿度预测

针对船舶舱室温湿度保持困难、数据难以预测的问题,提出了基于克隆选择算法的支持向量机集成方法。首先,利用克隆选择算法优化个体支持向量机,根据个体预测误差进行自适应集成;然后,对舱室温湿度时间序列数据样本化,采用支持向量机集成进行训练、测试;最后通过统计测试结果以及与BP神经网络、单支持向量机、GM(2,1)模型的预测误差对比发现,支持向量机集成模型可有效预测空调故障条件下船舶舱室温湿度的变化规律,为装备的使用和维护提供技术支持。

新一代快速部署方舱医院配套医疗设备的定制化设计方案

方舱医院被广泛用于灾害救援、战场救治、突发公共卫生事件防控等场景。目前,我国已进入第三代方舱医院的研制阶段。方舱医院的整体效能与配套医疗设备的性能直接相关。在研制阶段探讨方舱医院配套医疗设备的定制化设计方案,可保证医疗设备的配置与方舱医院的功能相匹配,从而更好地发挥方舱医院的整体效能。该研究针对方舱医院中占主体地位的急救设备、检验设备和影像设备,详细分析定制化设计方案。定制化设计的重点在于有限空间适应性、功能集成性、可快速部署、轻便性、抗震性、极端环境适用性、以及影像设备的低剂量高品质成像,并注重智能化功能融入。该研究可用于指导方舱医院配套医疗设备的定制化研制、选型及升级改造。

面向垃圾分类的全柔性多车舱车辆调度优化研究

垃圾分类运输是垃圾分类政策有效实施的重要环节。现有分类运输方法以单车舱专用车辆为主,易造成车辆资源浪费、垃圾收集点拥堵等问题。为此,本文引入能同时独立运输多种垃圾的多车舱车辆,依托我国垃圾收运实际情况,对车舱设置、收运模式等进行分析;以此为基础提出全柔性多车舱车辆路径问题(full flexible-MCVRP)及优化模型,并采用遗传算法进行求解。实际算例表明,与现有专用车辆分类调度方案相比,本文所给多车舱车辆调度方案总行驶路径更短,收运效率更高。进一步,针对几种典型城市生活区域,研究了垃圾分类占比对车舱分配方案的影响,为多车舱车辆设计提供参考。

电动汽车座舱内部噪声的非线性心理声学烦恼度建模

拟研究电动汽车座舱内部噪声特性对声学舒适性的影响。通过道路试验获取4种典型路面工况下某型电动汽车在不同车速下的舱内噪声,计算分析其心理声学参数,开展烦恼度主观评价实验,并基于非线性Zwicker心理声学烦恼度及其修正模型进行建模研究。结果显示,随着车速和路面粗糙程度变大,响度逐渐提高,尖锐度也随车速增大而变大;Zwicker心理声学烦恼度模型更适用于电动汽车座舱内部噪声。

耦合因素特征提取下船舶舱室通风设计方法

针对船舶舱室通风设计仅考虑单一因素,未考虑其他因素特征,影响船舶通风效率的问题,研究耦合因素特征提取下船舶舱室通风设计方法。将船舶舱室通风系统视为耦合系统,引入信息准则,利用牛顿方法提取影响船舶舱室通风效果的关键耦合因素特征。基于耦合因素特征提取结果,利用知识组件构建船舶舱室通风系统的数学模型,确保舱室空气流通顺畅。选取计算流体动力学软件模拟船舶舱室通风情况,依据模拟结果,进行船舶舱室通风设计的计算分析、调整与优化,获取船舶舱室通风系统的通风方式、换气次数等设计指标,确定最终的船舶舱室通风设计方案。实验结果表明,采用该方法设计的船舶舱室通风系统,满足换气次数要求,送风量与抽风量降低幅度明显,有效提升了通风系统的通风效率。

舱外设备箱体模拟海洋大气环境中的加速腐蚀试验与结果分析

目的 研究模拟海洋大气环境对舱外设备箱体腐蚀行为的影响,为快速评价舱外设备箱体原材料、原结构、原表面技术状态改进优劣提供技术和方法支撑。方法 根据XX舱外设备箱体实际服役环境剖面、腐蚀损伤状况,制定含海水模拟、湿热、维护保养及检查阶段等3个模块的实验室模拟海洋大气环境加速谱,运用外观、扫描电镜(SEM)、金相显微镜、X射线能谱(EDS)等表征技术,研究设备箱体在12个循环周期的宏微观形貌和腐蚀产物元素含量分布,并对标准金属铝和钢的同步实验室试验与XX近海户外自然环境下的腐蚀效应进行对比。结果 12个循环周期结束后,底座铝合金严重腐蚀,呈现明显的晶间腐蚀,并产生大量腐蚀产物,腐蚀产物主要含有O、Na、Al、Si、Cl、Ca、Mn、Fe等元素,其腐蚀形貌及程度与实际服役5 a的底座一致。标准金属铝和钢加速试验120 d的腐蚀效应分别等效XX近海大气试验4.65 a和10.57 a。结论 海水模拟、湿热、维护保养及检查阶段等3个模块的实验室模拟循环试验能较好地模拟XX舱外设备箱体经历的环境,其腐蚀与实际服役环境下的腐蚀程度相近,实现了基于短期内完成3~5 a的海洋运行验证。

航天器密封舱水分含量测量与除水工艺方法研究

航天器密封舱在进行真空热试验时处在真空容器内部,常规的水分含量测量和除水方法均无法满足密封舱除水要求。本文针对航天器密封舱在真空热试验时的除水难题,设计了一套适合密封舱内水分含量测量的装置,经过标定确保其满足真空环境下水蒸气含量的测量要求。设计的密封舱除水系统通过双向密封法兰与密封舱连接,可以在真空容器外完成对密封舱的除水。试验验证结果表明,该除水方法能够保证在真空热试验过程中密封舱内气体的露点温度低于0℃。

新型船舶轻量化整体隔音舱室的研究与设计

提出一种国内首创的船舶轻量化整体舱室装置设计方案,该方案深入应用于船舶舱室领域以及轮机机械领域。这一创新设计,旨在提升船舶舱室的舒适性和安全性,同时降低船舶的整体重量,提高燃油效率。该装置的独特之处在于,它可以通过限位卡合结构,对船舶舱室内的一些家用家具进行精确的限位固定。这种方式相比于传统的膨胀螺丝等固定方法,更具灵活性和便捷性。当需要拆卸家具时,限位卡合结构可以迅速解锁,实现快速拆卸。这一设计大大提高了船舶舱室的实用性和人性化程度。此外,该装置还在舱室的墙壁以及顶部采用了石膏板和隔音棉,取代了传统的泡沫板或水泥板。这种创新的设计,不仅能有效提升舱室的隔音效果,还能进一步减轻船舶重量,提高燃油效率。总体来说,这种新型的船舶轻量化整体舱室装置设计理念,将为船舶行业带来全新的变革。它不仅提升了船舶的性能,提高了船舶舱室的舒适度,也为船舶制造带来更高的效率和更低的成本,将对我国船体建造方式产生重要影响,并提供一种全新的思路。

基于KANZI Studio的汽车虚拟仪表三维场景重构技术研究与实现

随着智能座舱技术的快速发展,针对现有汽车仪表场景重构的显示信息不全和效果不达标的问题,二维场景重构技术已无法满足虚拟仪表发展需要。该文利用KANZI Studio汽车HMI专用开发工具,提出了一种实现虚拟仪表三维场景重构效果的方法,并提出效果优化方案。经测试表明,该方法可以解决目前二维场景重构技术的不足,将三维场景重构研究引入到仪表显示端;另将开发周期减少至传统开发工具的50%,有效地降低了三维场景重构的开发难度,能够在保证30帧流畅运行的条件下满足功能要求,最终通过实车验证并在某量产车型上得到应用。

复杂地下工程施工风仓风量分配情况和局部阻力系数研究

为解决多掌子面且掌子面需风量间存在较大差异的地下工程施工通风节能问题,以多进出口隔板式风仓为对象,通过数值模拟方法,将进风量和隔板覆盖率作为自变量,研究风仓出风量分配情况和局部阻力系数。结果表明:(1)风仓出风量分配情况和局部阻力系数仅与风仓自身的结构形式有关,与进风量无关;(2)隔板式风仓出风管转角处会形成“三角状”高速区,隔板覆盖率越大,高速区内风流速度越快,高速区越短;(3)可通过改变隔板覆盖率,实现对风仓出风量的调节,并给出了风仓无隔板出风口出风量占比与隔板覆盖率之间的函数关系式;(4)风仓隔板覆盖率超过40%时,局部阻力系数会显著增加,并给出了隔板覆盖率与风仓各个出风口局部阻力系数的函数关系式,供后续研究和相关单位进行参考。