Height connection across sea by using satellite altimetry data sets,ellipsoidal heights,astrogeodetic deflections of the vertical,and an Earth Gravity Model

Islands and the mainland are separated by seas,and the distances between them might be so long that the height on the mainland cannot be exactly translated to the islands,resulting in different height systems on the mainland and the islands.In this study,we used astrogeodetic deflections of the vertical and ellipsoidal heights of points on the mainland and island near their coastlines to implement height connection across sea areas.First,the modeled gravity and modeled astrogeodetic vertical deflections of segmentation points along connecting routes over the sea between the mainland and the island were determined by Earth Gravity Model(EGM),and the ellipsoidal heights of segmentation points were determined by the satellite altimetry data sets.Second,we used a linear interpolation model to increase the precision of the vertical deflections of segmentation points.Third,we computed the geopotential difference of points between the mainland and the island using a method derived from geopotential theory and the astronomical leveling principle.Finally,we estimated the normal height of the point on the island using the geopotential-difference iterative computation approach.Using observed data of normal heights,ellipsoidal heights,and astrogeodetic vertical deflections referring to height sites in Qingdao,Shandong Province,we conducted a numerical experiment involving the normal height connection across sea regions.We determined the data of the ellipsoidal heights and gravity of segmentation points along the connecting route across the water in the numerical experiment using DTU10.The distance of the height connection across the sea was approximately 10.5 km.According to China's official leveling specifications,the experimental results met the criterion of third-class leveling precision.

Route Height Connection Across the Sea by Using the Vertical Deflections and Ellipsoidal Height Data

Distance between the main land and island is so long that it is very difficult to precisely connect the height datum across the sea with the traditional method like the trigonometric leveling, or it is very expensive and takes long time to implement the height transfer with the geopotential technique. We combine the data of GPS surveying, astro-geodesy and EGM2008 to precisely connect the orthometric height across the sea with the improved astronomical leveling method in the paper. The Qiongzhou Strait is selected as the test area for the height connection over the sea. We precisely determine the geodetic latitudes, longitudes, heights and deflections of the vertical for four points on both sides across the strait. Modeled deflections of the vertical along the height connecting routes over the sea are determined with EGM2008 model based on the geodetic positions and heights of the sea segmentation points from DNSC08MSS model. Differences of the measured and modeled deflections of the vertical are calculated at four points on both sides and linearly change along the route. So the deflections of the vertical along the route over the sea can be improved by the linear interpolation model. The results are also in accord with those of trigonometirc levelings. The practical case shows that we can precisely connect the orthometric height across the Qiongzhou Strait to satisfy the requirement of order 3 leveling network of China. The method is very efficient to precisely connect the height datum across the sea along the route up to 80 km.

Numerical and Experimental Study of the 3D Effect on Connecting Arm of Vertical Axis Tidal Current Turbine

Vertical axis tidal current turbine is a promising device to extract energy from ocean current. One of the important components of the turbine is the connecting arm, which can bring about a significant effect on the pressure distribution along the span of the turbine blade, herein we call it 3D effect. However, so far the effect is rarely reported in the research, moreover, in numerical simulation. In the present study, a 3D numerical model of the turbine with the connecting arm was developed by using FLUENT software compiling the UDF（User Defined Function） command. The simulation results show that the pressure distribution along the span of blade with the connecting arm model is significantly different from those without the connecting arm. To facilitate the validation of numerical model, the laboratory experiment has been carried out by using three different types of NACA aerofoil connecting arm and circle section connecting arm. And results show that the turbine with NACA0012 connecting arm has the best start-up performance which is 0.346 m/s and the peak point of power conversion coefficient is around 0.33. A further study has been performed and a conclusion is drawn that the aerofoil and thickness of connecting arm are the most important factors on the power conversion coefficient of the vertical axis tidal current turbine.

Improvement of reverse blocking performance in vertical power MOSFETs with Schottky–drain-connected semisuperjunctions

To enhance the reverse blocking capability with low specific on-resistance,a novel vertical metal-oxidesemiconductor field-effect transistor（MOSFET） with a Schottky-drian（SD） and SD-connected semisuperjunctions（SDD-semi-SJ）,named as SD-D-semi-SJ MOSFET is proposed and demonstrated by two-dimensional（2D） numerical simulations.The SD contacted with the n-pillar exhibits the Schottky-contact property,and that with the p-pillar the Ohmic-contact property.Based on these features,the SD-D-semi-SJ MOSFET could obviously overcome the great obstacle of the ineffectivity of the conventional superjunctions（SJ） or semisuperjunctions（semi-SJ） for the reverse applications and achieve a satisfactory trade-off between the reverse breakdown voltage（BV） and the specific on-resistance（R_（on）A）.For a given pillar width and n-drift thickness,there exists a proper range of n-drift concentration（N）,in which the SD-D-semi-SJ MOSFET could exhibit a better trade-off of R_（on）A-BV compared to the predication of SJ MOSFET in the forward applications.And what is much valuable,in this proper range of N,the desired BV and good trade-off could be achieved only by determining the pillar thickness,with the top assist layer thickness unchanged.Detailed analyses have been carried out to get physical insights into the intrinsic mechanism of R_（on）A-BV improvement in SD-D-semi-SJ MOSFET.These results demonstrate a great potential of SD-D-semi-SJ MOSFET in reverse applications.

Seismic behavior and mechanism analysis of innovative precast shear wall involving vertical joints

To study the seismic performance and load-transferring mechanism of an innovative precast shear wall(IPSW) involving vertical joints, an experimental investigation and theoretical analysis were successively conducted on two test walls. The test results confirm the feasibility of the novel joints as well as the favorable seismic performance of the walls, even though certain optimization measures should be taken to improve the ductility. The load-transferring mechanism subsequently is theoretically investigated based on the experimental study. The theoretical results show the load-transferring route of the novel joints is concise and definite. During the elastic stage, the vertical shear stress in the connecting steel frame(CSF) distributes uniformly; and each high-strength bolt(HSB)primarily delivers vertical shear force. However, the stress in the CSF redistributes when the walls develop into the elastic-plastic stage. At the ultimate state, the vertical shear stress and horizontal normal stress in the CSF distribute linearly; and the HSBs at both ends of the CSF transfer the maximum shear forces.

CONNECTIONS AND GEODESIC CHARACTERISTIC OF EQUATIONSOF MOTION FOR CONSTRAINED MECHANICAL SYSTEMS

The geodesic characteristic of equations of motion for nonautonomous constrained mechanical systems is studied in the modern setting of global differential geometry. A necessary and sufficient condition for the dynamical flow of a nonautonomous mechanical system with geodesic characteristic was obtained with respect to a connection of 1-jet bundle. The dynamical flow concerning the non-autonomous case motion of an nonautonomous mechanical system with constraints can be always represented by the motion along the geodesic line of torsion-free connection on 1-jet bundle, which is different from the case in an autonomous mechanical system.

垂直式重力储能系统的研究进展和关键技术

基于固体重物的重力储能技术因其不依赖水资源、选址灵活、效率高等优势,未来有望成为我国北方和西北缺水地区重要的储能技术之一,可以很好地满足大规模可再生能源电力并网对储能技术的需求。然而,由于固体重物的不可流动性和不连续性,重物启停和切换过程会对机械传动和电网系统造成冲击,是固体重力储能区别于抽水蓄能的重要特征。本文首先介绍了近年来国内外基于竖井和地面构筑物的垂直式重力储能技术的研发现状和示范工程,并进一步对垂直式重力储能系统垂直提升、水平转移和自动接驳机械传动技术,以及发电电动机和并网控制技术中存在的核心技术难题进行了分析,最后对垂直式重力储能技术未来的发展趋势进行了展望。研究表明,垂直式重力储能系统尽管技术方案较多,但在重载快速提升和转移、重物启停和切换过程控制、并网控制和能效提升等方面还存在诸多技术难题有待解决,后续通过技术提升可进一步降低系统建造成本并提高系统运行的效率和寿命,有望在近期获得一定的示范应用。

装配式混凝土剪力墙结构接缝连接研究进展

装配式剪力墙结构拼装时存在大量的水平接缝和竖向接缝,由于剪力墙的刚度较大,接缝连接处易存在刚度不足引起的损伤集聚问题,成为影响结构整体性和抗震性能的决定性因素。总结了国内外正在发展的预制装配式剪力墙结构水平和竖向接缝的连接形式,并对各类连接形式的构造特点、抗震性能、应用优势和技术瓶颈进行了系统阐述和分析,在此基础上探讨了装配式剪力墙结构接缝连接技术的发展方向。结果表明:目前湿式连接技术已较为成熟且被广泛应用,但仍存在现场湿作业量大、质量不易检测和控制等问题;干式连接技术工业化程度高,但对施工精度的要求也高,可能产生的螺栓松动、锈蚀以及磨损问题限制了其工程应用;将消能减震技术融入竖向接缝连接,利用超高性能混凝土实现水平接缝连接,并结合可恢复功能防震技术,是未来装配式剪力墙结构高质量发展的新增长点。

地下工程竖井定向连接四边形法最优图形分析

为了提高地下工程竖井定向精度,阐释了连接四边形法竖井定向方法,用一个角和一条边为参数确定对称四边形,构建了连接四边形严密平差模型,采用间接平差进行网形精度评估。编写程序遍历条件角和条件边计算定向边精度,绘制等值线,定量分析连接四边形法最优图形。该研究对于地下工程竖井定向具有实际应用价值。

某型飞机垂直安定面-方向舵关键参数对模态频率影响的研究

目的 研究飞机垂直安定面-方向舵装配参数对固有频率的影响。方法 通过有限元模型分析,研究铰链轴位置变化和舵机刚度调整对垂尾安定面-方向舵模态频率的影响。结果 下铰接点偏移对方向舵频率的影响最大,频率随偏移量增加而降低,最大降低0.36 Hz;上铰接点次之,前3阶频率降低,第4阶频率增加,最大变化量分别为0.203、0.08 Hz;中铰接点影响最小,频率变化微小,最大为0.028 Hz。增加舵机刚度时,前4阶频率均上升,但前3阶在刚度增加5倍以下时上升较快,超过5倍后趋于稳定,而前2阶频率受刚度的影响不大。第4阶频率在刚度增加10倍以下时明显上升。结论 垂尾安定面与方向舵的连接铰链在装配时不同轴,下铰接点偏移,对垂尾结构的前4阶模态频率的影响最大,上铰接点偏移次之,中铰接点偏移对垂尾结构的前4阶模态频率没有影响。舵机的刚度增加,垂尾的前4阶模态频率增加,对第3、4阶模态的影响尤为显著。

新型横向连接装配整体式榫卯剪力墙结构抗震性能模拟分析

为加强装配整体式剪力墙的竖向接缝性能和墙体的整体性,在传统榫卯接缝的基础上,研究提出一种采用新型横向连接的装配式榫卯剪力墙,设置横向凹槽处的封闭环形钢筋闭合连接,并与纵向孔洞处的竖向钢筋绑扎形成钢筋骨架,以提高剪力墙的整体稳定性。设置1组现浇剪力墙、1组传统装配式榫卯连接装配式剪力墙、1组采用新型横向连接的装配式榫卯剪力墙,使用ABAQUS有限元软件模拟在低周往复荷载作用下不同墙体的受力情况及破坏过程,并且对比分析不同竖向接缝对剪力墙工作性能和抗震能力的影响。研究结果表明,采用新型榫卯横向连接的装配式榫卯剪力墙的刚度和承载能力与现浇剪力墙基本一致,能够满足“等同现浇”的要求。

新时期运河战略及平陆运河规划建设实践

中国在世界的运河开凿利用和运河经济文化交流中发挥着引领性和示范性作用。综述我国运河的开发历史、世界十大运河的基本情况和功能价值、我国近代百年运河梦想和谋划。进入新时代,内河航运开发向全面考虑国民经济、产业布局、社会环境等各方面综合效益转变。阐述新时期跨水系连通运河规划背景和重大意义,重点介绍平陆运河这一世纪运河工程的规划历程、研究工作的重难点和工程技术创新点,可为相关工程的规划咨询提供借鉴。

带高位大悬挑的多塔连体结构超限分析与设计

武汉全球公共采购交易服务总部基地项目6~8号楼是三塔多重复杂连体结构,各塔间刚性连接体跨度25.2m,顶部两层南侧和东侧分别设置悬挑8.4m和6.0m的高位长悬挑结构,是具有6项不规则项的超限高层建筑。工程混合采用混凝土结构、钢结构和组合结构体系,并使用预应力技术。本文介绍了该项目抗震性能化设计过程,采用多种软件对小震、中震和大震作用下的结构及构件性能进行分析。对以下重点问题进行专项分析:采用时程法和反应谱法得出6度区连体和悬挑结构的最小竖向地震作用系数;分析温度作用下超长结构的楼板应力,分析悬挑结构在其上下层引起的楼板应力,验算大震作用下连接体楼板的抗剪承载力;验算连接体楼盖舒适度。结合分析结果和工程特点,采取相应加强措施,实现了良好的抗震效果。

型钢混合连接装配式混凝土剪力墙结构受力机理研究

结合钢筋混凝土结构和钢结构的优势,设计一种型钢-螺栓-后浇混凝土装配式剪力墙型钢混合连接。基于ABAQUS有限元软件建立混合连接的剪力墙模型,探究低周往复荷载作用下该混合连接预制剪力墙的受力性能,主要分析模型的破坏形态、受力机制、变形曲线、特征承载力等,并扩展分析了材料强度、轴压比、连接件数量、型钢截面高度等参数对模型受力性能影响。结果表明:装配式剪力墙破坏形态为压弯破坏,破坏时钢连接件仍保持完整,符合“强连接,弱墙肢”的基本设计理念;装配式剪力墙具有较好的承载力、延性和刚度;轴压比对结构承载力影响显著,型钢混合连接间距的增大能有效提升剪力墙延性。建立了型钢混合连接抗剪需求承载力计算模型和公式,并与国内外规范计算值对比分析,公式计算值和BS EN 1992欧洲规范计算值分别与模拟值的误差在15%和20%以内,均可用于型钢混合连接剪力墙竖缝受剪承载力设计参考。

结合井口对称点的竖井联系测量的应用

竖井联系测量中定向比较困难。为此,利用井口点对称性质,可减弱竖轴倾斜误差、投点误差和对中误差对水平角的影响,测定导线连接角,为隧道内导线建立起始或终止方向。对于两井定向,增加水平角校核条件,仍可采用无定向导线计算。结合某隧道扩建工程,验证该方法的有效性。该方法可结合其他定向方法,为一井定向导入较准确定向,对两井定向也有参考作用。

基于多策略融合的改进RRT路径规划算法

针对传统快速扩展随机树(RRT)及其衍生算法在路径规划时生成路径效率较低、无效探索点较多等问题,提出一种多策略融合的改进RRT算法。首先利用启发式选择策略确定最合适的扩展节点,然后结合基于目标偏置的自适应动态步长策略,使随机树始终向目标点区域扩展,最后通过垂距断点预优化的跳点连线策略去除冗余点,生成一条没有较大转折角的最短安全路径。通过不同复杂程度的仿真实验和现实环境实验对该算法进行测试。结果表明,与RRT、RRT*和Bi-RRT*算法相比,本文算法在时间消耗上分别减少了大约80%、50%和60%,在路径节点数上分别减少了大约65%、40%和35%。机器人依据该算法可以高效生成一条无碰撞,仅包含起始点、目标点和非突兀转折点的最优路径。

考虑竖向地震作用的连体结构地震易损性分析

为了探讨竖向地震分量对连体建筑结构抗震性能的影响,以某连体结构为例,利用增量动力分析方法研究了水平地震作用、水平向与竖向联合作用下连体结构的地震响应及易损性。结果表明:与水平向地震动作用相比,在竖向与水平向地震动联合作用下,连体结构最大层间位移角明显较大,二者之间的差异随着地震动幅值的增加而增加;竖向地震的作用增加了连体结构发生各级破坏的概率,显著增加了其发生“修复后使用”及以上等级破坏的可能性,但总体而言,三向地震作用下该连体结构仍满足“小震不坏、中震可修、大震不倒”的抗震设防目标。

无框瓦楞夹芯板极限抗拔力及家具角部结合性能的研究

无框瓦楞夹芯板是以立式瓦楞纸和中纤板为基材,经胶合而成的一种新型家具板材。本研究采用单因素分析法对影响该板材极限抗拔力的各项因素进行分析,同时通过拉伸和压缩试验测试角部结合性能,分析偏心件类型、偏心件位置和预埋螺母种类对角部结合强度的影响,为其在家具的生产应用中提供更加全面、系统的指导。结果表明:在极限抗拔力试验中,不同类型预埋螺母的极限抗拔力大小依次为拉铆螺母>小螺纹胶塞>大螺纹胶塞。对于小螺纹胶塞,当表板厚度为5 mm、螺纹间距为1 mm、引导孔直径为9.4 mm时,板材的极限抗拔力最大。在角部结合性能试验中,层板托作为偏心件强度大于偏心轮,拉铆螺母作为预埋螺母强度大于胶塞。在芯层板上使用偏心件可呈现出良好的力学性能。本文提出的拉铆螺母和层板托作为无框瓦楞夹芯板三合一连接件的组成部分具有较好的角部结合性能,为瓦楞夹芯板家具连接件的设计提供了新的思路。

大跨度齿板连接木桁架搁栅楼盖竖向振动性能试验研究

为研究齿板连接木桁架搁栅楼盖的人致振动响应,对12m跨度齿板连接木桁架搁栅楼盖振动性能进行了足尺试验研究,分析了横撑和隔墙对木楼盖振动特性、楼盖刚度的影响,分析了单人步行荷载和自由落体冲击荷载作用下木楼盖的振动响应。结果表明:木楼盖前三阶振型符合预期,单跨木楼盖的基本自振频率在8Hz以下,低于连跨形式木楼盖的基本自振频率;安装横撑和设置隔墙都可以增加木楼盖的前三阶频率;在不同位置安装横撑均可提高木楼盖的刚度,减小木楼盖的静态挠度,均匀安装4排横撑可将楼盖中心静态挠度降低47.5%;不同方向步行荷载激励下木楼盖的振动响应略有不同,纵向行走而致的振动响应较大,横向较小,安装隔墙后木楼盖中心的振动响应能降低40%左右;木楼盖的纵向振动传递大于横向和斜向两个方向,安装隔墙有助于木楼盖振动的传递。

深圳朗峻广场项目复杂高层结构设计

朗峻广场项目是多个整体建筑体块错落叠合而成的复杂建筑,其造型独特,具有45m跨度刚性连接连体、斜撑转换、竖向构件收进和大悬挑等特征,结构采用框架-多筒体剪力墙体系。阐述了刚性连体构成、转换结构的设计选型与思路,重点介绍了筒体剪力墙墙肢的关键设计要点。此外,根据项目特点确定结构的性能目标,提出了小震设计参数结果的合理提取方法和中震的设计原则,复核结构在大震下的抗震性能并根据结果采取适宜的抗震措施。结果表明本工程结构具有较好的抗震性能,采用的设计方法可行。