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Sample records for bollards

  1. Development of Shallow Footing Anti-Ram Bollard System Through Modeling and Testing

    Institute of Scientific and Technical Information of China (English)

    LAN Shengrui; CRAWFORD John E; XIN Xudong

    2006-01-01

    In past terrorist attacks,vehicle borne improvised explosive devices (VBIED) have been the primary manner of attacking buildings and infrastructures.Preventing unauthorized vehicles from approaching a protected area with anti-ram systems would maintain an established standoff distance against moving and stationary vehicles and consequently reduce blast and debris threats.This strategy has been considered the first line of defence against terrorists.Several types of anti-ram devices have been developed in accordance with U.S.Department of State K-rating criteria,for example,wedge barriers,rising beams,sliding/swing gates,and drop arms.However,these devices typically need a deep foundation for installation and can't be implemented into many locations where a depth of excavation is limited in order to protect utility lines of buildings and infrastructures.This paper presents a recent development of a series of shallow footing anti-ram bollard systems (SFABS) that can satisfy K-12 rating with only five-inch thick footing.A high-fidelity physics based finite element technique with a vehicle crash model is used for predicting anti-ram capacity and determining design parameters of the SFABS.Full-scale vehicle crash tests of the developed SFABS systems have been carried out to validate the design and analysis.

  2. Research for the Simplified Design Method of Anti-Ram Bollards Subject to Vehicle Impact Load%车辆冲击荷载下防撞杆的简化设计方法研究

    Institute of Scientific and Technical Information of China (English)

    王震; 李国强; 陈素文; 孙建运

    2013-01-01

    近年来发生的规模较大的恐怖袭击活动中,车载简易爆炸装置(VBIED)逐渐成为建筑结构与基础设施安全的重大危害.防撞杆作为重要建筑周边的第1道安全屏障,能够有效地控制潜在威胁车辆对建筑物的侵入.因此,以防撞杆为代表的阻拦型防爆路障在英、美等发达国家已有广泛应用.为了规范阻拦型防爆路障的试验测试及评定标准,英、美等国都相继颁布了本国阻拦型防爆路障的评测规范,其中美国规范中提出了一套K级抗撞等级标准.利用显式动力分析软件LS-DYNA的强大模拟功能,结合美国规范中的K4等级对应工况,提出了一套适用于钢管混凝土防撞杆的简化设计方法,可供今后的工程应用参考.%In past large-scale terrorist attacks, vehicle-borne improvised explosive devices ( VBIED) have become the major hazard for the safety of buildings and infrastructures. As the first line of defense against terrorism,anti-ram bollards could control the penetration ofvehicles with potential threat to buildings effectively. Therefore,anti-ram bollards have been widely used in the developed countries, such as U. S. and Britain. In order to adopt a unified test and evaluation standard of vehicle barriers,the governments of U. S. and Britain have established standards for vehicle barrier devices respectively. A criterion of K-level was given in the U. S. specification. By using of the LS-DYNA software.this paper presents a simplified design method of anti-ram bollards subject to vehicle impact load according to the K4 level,which could give a reference for the future engineering design.

  3. Propeller Design Optimization for Tunnel Bow Thrusters in the Bollard Pull Condition

    Science.gov (United States)

    2012-06-01

    rpm PWM Delay Brake/Stop Response Time 100 ms Torque Constant 0.927 N∙m/ Apk Gains Velocity Parameters Vp 32000 Velocity Tracking...brake/stop response time 100 ms Torque Constant 0.927 N∙m/ Apk Table 16: CME2 Motor Parameters Initial tuning for amplifier parameters. In

  4. Microwave Radiometric Measurement of Sea Surface Salinity.

    Science.gov (United States)

    1984-04-01

    potential problems of polution and urban water sup- plies. Although salinity can be measured from a surface vessel, economic consider- ations advocate...Washington, DC 20350 Commander Naval Sea System Commandaa ComAinder ATTN: Mr. C. Smith, NAVSEA 63R* Nval Air Development Center "’-’. "Washington, DC...20362 ATTN: Mr. R. Bollard, Code 2062% .’* Warminster, PA 18974 • .’.Commander CNaval Sea System CommandCoimCander Headquarters Naval Air Systems

  5. Verification of CFD analysis methods for predicting the drag force and thrust power of an underwater disk robot

    Directory of Open Access Journals (Sweden)

    Joung Tae-Hwan

    2014-06-01

    Full Text Available This paper examines the suitability of using the Computational Fluid Dynamics (CFD tools, ANSYSCFX, as an initial analysis tool for predicting the drag and propulsion performance (thrust and torque of a concept underwater vehicle design. In order to select an appropriate thruster that will achieve the required speed of the Underwater Disk Robot (UDR, the ANSYS-CFX tools were used to predict the drag force of the UDR. Vertical Planar Motion Mechanism (VPMM test simulations (i.e. pure heaving and pure pitching motion by CFD motion analysis were carried out with the CFD software. The CFD results reveal the distribution of hydrodynamic values (velocity, pressure, etc. of the UDR for these motion studies. Finally, CFD bollard pull test simulations were performed and compared with the experimental bollard pull test results conducted in a model basin. The experimental results confirm the suitability of using the ANSYS-CFX tools for predicting the behavior of concept vehicles early on in their design process.

  6. On the possibility of the in-cell molecular motors working as cargo moorings only

    CERN Document Server

    Lisowski, Bartosz

    2012-01-01

    Although active transport is considered the most efficient way of depositing materials in the appropriate compartments within living cells, free diffusion remains the energetically cheapest and most widespread determinant of the in-cell dynamics. Here we investigate the hypothesis of cargoes - vesicles or organelles - being transported by the means of free diffusion, limited spatially by the molecular motors. Routinely navigating through ever-changing and unsteady environment, utilizing chemical energy (e.g. from hydrolyzing ATP), as the result they transport cell's crucial components, such as neurotransmitters and organelles. In our model the motor, which we identify with kinesin-1 walking along the microtubule, tethers the cargo in the same manner as a mooring rope attached to a bollard holds a ship from drifting toward the open sea. We study the model behavior in the context of optical trap single molecule experiments, mimicking their procedures in our simulations and investigate how the mechanical propert...

  7. Simulation of a sprinter. Part II. Implementation on a programmable calculator.

    Science.gov (United States)

    Vaughan, C L

    1983-01-01

    Although successful models have been developed to simulate a sprinter's performance, they are often complex and sophisticated, requiring a main frame environment and expensive monitoring equipment. These disadvantages preclude the wide-spread use of the models by practitioners. This paper presents a method in which the necessary data can be easily gathered--using a tape measure, six stop watches and bollards, a starting gun, and a bathroom scale. A simple algorithm is presented for calculating the parameters of a previously defined model, and implemented on hand-held programmable calculators, the Casio FX-502P and HP41C. The model calculates the sprinter's initial horizontal acceleration, maximum horizontal velocity and can be used to predict the time for any given race distance. The model can therefore be used to evaluate the sprinter's current performance as well as indicate his potential if he were able to reach and maintain maximum velocity.

  8. I-Xe systematics of the impact plume produced chondrules from the CB carbonaceous chondrites: Implications for the half-life value of 129I and absolute age normalization of 129I-129Xe chronometer

    Science.gov (United States)

    Pravdivtseva, O.; Meshik, A.; Hohenberg, C. M.; Krot, A. N.

    2017-03-01

    It is inferred that magnesian non-porphyritic chondrules in the CB (Bencubbin-type) carbonaceous chondrites formed in an impact generated plume of gas and melt at 4562.49 ± 0.21 Ma (Bollard et al., 2015) and could be suitable for the absolute age normalization of relative chronometers. Here xenon isotopic compositions of neutron irradiated chondrules from the CB chondrites Gujba and Hammadah al Hamra (HH) 237 have been analyzed in an attempt to determine closure time of their I-Xe isotope systematics. One of the HH 237 chondrules, #1, yielded a well-defined I-Xe isochron that corresponds to a closure time of 0.29 ± 0.16 Ma after the Shallowater aubrite standard. Release profiles and diffusion properties of radiogenic 129*Xe and 128*Xe, extracted from this chondrule by step-wise pyrolysis, indicate presence of two iodine host phases with distinct activation energies of 73 and 120 kcal/mol. In spite of the activation energy differences, the I-Xe isotope systematics of these two phases closed simultaneously, suggesting rapid heating and cooling (possibly quenching) of the CB chondrules. The release profiles of U-fission Xe and I-derived Xe correlate in the high temperature host phase supporting simultaneous closure of 129I-129Xe and 207Pb-206Pb systematics. The absolute I-Xe age of Shallowater standard is derived from the observed correlation between I-Xe and Pb-Pb ages in a number of samples. It is re-evaluated here using Pb-Pb ages adjusted for an updated 238U/235U ratio of 137.794 and meteorite specific U-isotope ratios. With the addition of the new data for HH 237 chondrule #1, the re-evaluated absolute I-Xe age of Shallowater is 4562.4 ± 0.2 Ma. The absolute I-Xe age of the HH 237 chondrule #1 is 4562.1 ± 0.3 Ma, in good agreement with U-corrected Pb-Pb ages of the Gujba chondrules (Bollard et al., 2015) and HH 237 silicates (Krot et al., 2005). All I-Xe data used here, and in previous estimates of the absolute age of Shallowater, are calculated using 15.7

  9. Application of Inventor 3-D Design Software to Water Conservancy and Hydropower Engineering%Inventor三维设计软件在水利水电工程中的应用

    Institute of Scientific and Technical Information of China (English)

    刘敦煌

    2012-01-01

    The software Inventor is an intelligent tool for 3-D mechanical design. It is used in the present study to design mechanical equipment such as steel structure, bollard, and flume with variable slope, and has efficiently and accurately solved practical engineering problems. The basic functions of Inventor are presented by introducing design examples, which shows that Inventor is a crucial tool for the description and expression of engineering techniques and scientific research results. Utilization of Inventor is a key to master engineering design, and is essential for the creativity and innovation of engineering technique and scientific research%Inventor软件是全面智能化的三维机械设计工具.应用Inventor软件设计了钢结构、系船墩、变坡水槽等机械设备,高效准确地解决了实际水力学工程问题.结合设计实例介绍了软件的基本功能,表明Inventor三维软件是工程技术及科学研究的重要工具.进一步掌握其技术和技巧,即可进入设计的前沿,辅助实现工程技术及科学研究的创意与创新.

  10. PREDICTION OF LOADING DISTRIBUTION AND HYDRODYNAMIC MEASUREMENTS FOR PROPELLER BLADES IN A RIM DRIVEN THRUSTER

    Institute of Scientific and Technical Information of China (English)

    CAO Qing-ming; HONG Fang-wen; TANG Deng-hai; HU Fang-lin; LU Lin-zhang

    2012-01-01

    This article presents an approach which employs a commercial Reynolds-Averaged Navier-Stokes (RANS) solver to predict the steady wake field and loading distributions for a rim driven thruster.Four different cases of propeller blades are chosen to be calculated with the presented method.The propeller blade radial circulation and chordwise circulation density distributions are analyzed.The maximum radial circulation is found at the blade tip,which is different from conventional shaft drven propeller.The numerical results indicate that there is no tip leakage vortex in rim driven propulors.But there exist the tip joint vortex and the root region vortex.Bollard characteristics are calculated by taking rim surface effect into account.From the predicted results the second case in this paper is selected as the final one to perform hydrodynamic experiment.The calculation results with empirical rim surface corrections are compared with the measurement.It shows that the developed numerical method can well predict hydrodynamic performances of the rim driven thruster.

  11. Model test vs virtual simulation of a VLCC FPSO hookup%VLCC级FPSO海上连接的模型试验及虚拟模拟

    Institute of Scientific and Technical Information of China (English)

    郝军; 孙玉柱; 吴子全; Alan WANG

    2009-01-01

    This paper describes the model test and the virtual simulation respectively for the VLCC class FPSO hookup, as well as addresses their different applications to the mating operation between the FPSO and the soft yoke mooring system (SYMS) in extremely shallow water. The scope of the model test and the virtual simulation covers various installation stages including a series of positioning trials, positioning keeping and temporary mooring to the pre-installed SYMS mooring tower, pendulum mating, and yoke ballasting to storm-safe. The model test is to accurately verify bollard pull capacity to keep the FPSO in position and assess motion responses and mooring loads for the FPSO and installation vessels during various installation stages. The virtual simulation is to provide a virtual-reality environment, thus realistically replicating the hookup operation at the Simulation Test Center (STC) facility and identifying any deficiencies in key installation personnel, execution plan, or operation procedures. The methodologies of the model test and the virtual simulation addressed here can be easily extended to the deepwater applications such as positioning and installation operations of various floating systems.%阐述了VLCC级.FPSO海上连接的模型试验和虚拟模拟,以及其研究结果如何应用于指导FPSO与SYMS存极浅水中的连接作业.模犁试验和虚拟模拟研究范围覆盖了各安装阶段,包括海上就位试验、就位及连接临时交义缆、系泊腿连接、压载灌浆直至达到风暴安全状态.模型试验不仅可以核实FPSO就何拖拉力要求,而且可以确定FPSO和安装驳船的运动幅值和系泊力大小.而虚拟模拟则可以虚拟模拟环境,通过虚拟模拟确认关键作业人员、作业执行方案和作业程序中潜在的问题.该文介绍的模型试验和虚拟模拟方法可以进一步推广到各种浮式平台的深水应用中.