杆式破片不同攻角垂直侵彻硬铝靶板数值模拟

采用LS-DYNA显示分析,研究了杆式破片在不同攻角垂直侵彻硬铝靶板的响应,得出了不同着靶角度下破片侵彻能力,分析了临界速度、剩余速度、破口直径以及靶板塑性区域等参数,并总结了这些参数的变化规律。     

沥青温度敏感性指标评价与附加指标研究

分析了针入度指数评价沥青感温性能的优缺点,针对其不足之处,自行研发了可对多个温度下粘稠度进行测试的沥青稠度测试仪,引入了能在较宽温度范围内表征沥青感温性能的稠度-温度指数,并分析评价了该指标的合理性和可行性,提出了计算该指标的方法。测试误差和测试温度范围对指标影响的研究结果表明:稠度-温度指数有效地避免了针入度指数的缺点,可以作为沥青感温性的附加评价指标。     

探地雷达技术在岩溶地质勘探中的应用

以新建田德线初勘探地雷达实测结果为依据,分别从探测原理、技术方法、成果分析这几个方面,探讨了在岩溶异常发育地区,如何发挥探地雷达的工程物探技术的作用。运用探地雷达技术,探查并圈定了溶蚀破碎、溶洞、溶沟、溶槽等岩溶地质异常范围。     

交错直线间F(P,k)线的规律

本文对交错直线间的最长、最短及介于这两者间任一长度 F(P,k)线的方向线,从理论上进行了探讨,得出了普遍规律。并介绍了在科技领域实际应用中解决有关问题的方法,同时对规律以外各种情况作了分析,揭示了 F(P,k)线的存在与分布规律,以供作进一步研究时参考。     

江苏响水滩涂土壤圆锥指数试验研究

圆锥指数法(WES)是一种用来快速判断车辆通过性的方法。江苏沿海滩涂风力资源丰富,但滩涂土壤松软,普通车辆难以行驶,为保证风电开发施工设备在江苏沿海滩涂安全行驶通过而不发生陷车,三一电气有限责任公司自行设计了一种圆锥指数仪,用以测量滩涂土壤圆锥指数,判断车辆通过性。对响水滩涂T4风机位附近土壤的圆锥指数进行测量,得到了该区域扰动和非扰动两种情况下的土壤圆锥指数曲线,并对滩涂履带运输车的车辆圆锥指数进行了理论计算,根据试验和理论计算的结果进行了滩涂履带运输车实地行驶试验。试验表明,该型运输车在此区域通过性良好。该试验也为评估其它各种车辆在该地区的行驶通过性提供了数据参考。     

深圳地铁五号线海积淤泥地层基坑围护桩插入深度的研究

海积淤泥地层具有天然含水量高、渗透性低、压缩性高及抗剪强度低等特点,因此在海积淤泥地层修建地铁车站时,车站基坑围护结构的稳定性对安全施工至关重要。采用FLAC程序对海积淤泥地层地铁车站基坑围护结构桩体插入深度进行研究,分析桩体最大位移、最大剪力及基坑周边地表沉降等与插入深度的关系,给出适合于海积淤泥地层的桩体插入深度,并提出插入深度不足时的应对措施。     

车用冷却风扇安装位置对其性能影响的分析研究

根据某重型车用环形风扇的实际风筒试验过程建立了该风扇风筒仿真模型,并将计算结果与试验数据进行了比较,验证了模型的可靠性.利用该模型对不同风扇的轴向伸入距离、径向间隙进行仿真分析.结果表明,轴向伸入距离和径向间隙对风扇性能的影响十分显著:该风扇轴向伸入距离为75 mm、径向间隙为25 mm是较合理的安装距离:不同的轴向伸入距离对径向间隙的要求是不同的.     

Numerical simulation on truncated oval-nosed projectile penetrating into stiffened plate北大核心CSCD

[Objectives]In this paper, the numerical simulation method is used to study the anti-penetration performance and energy absorption mode of a stiffened plate, as well as the influence of different stiffened bars on the flight attitude of the projectile body.[Methods] Finite element software LS-DYNA is used to simulate the process of a truncated oval-nosed projectile penetrating a stiffened plate, and the results of the numerical simulation are compared with an experiment to verify the reliability of the numerical simulation method. The momentum method and mass equivalence method are used to predict the residual velocity of the projectile, and the applicability of different theoretical methods within different velocity ranges is compared. The deformation energy of different regions of the stiffened plate is then extracted to analyze the influence of the initial velocity of the projectile body on the energy absorption mode of the target plate. Finally, the structure of the stiffeners is changed and the influence of the relative position of the stiffeners on the penetration attitude of the projectile body is analyzed.[Results]The results show that the mass equivalence method is more accurate than the momentum method in predicting the residual velocity of the stiffened plate when the initial velocity of the projectile body is in the range of 300–900 m/s. The ratio of the deformation energy of the stiffened plate to the energy loss of the projectile body decreases with the increase of the initial velocity of the projectile body. The effect of a T-stiffened plate on trajectory is greater than that of a rectangular-stiffened plate.[Conclusions]The related calculation method and research results have certain reference value for research and engineering application surrounding the anti-penetration of stiffened plates. © 2023 Chinese Journal of Ship Research. All rights reserved.     

小管径垂直管水下排气完全携带点实验及分析

船用柴油机采用水下排气方式具有降低排气噪声、改善舱外空气质量等优点，在大型豪华游轮等特殊船舶中具有广泛应用前景。为防止海水由排气管倒灌入柴油机造成事故，需弄清水下排气管内水倒流发生的条件。对大管径垂直管防止水倒灌临界条件即完全携带点的已有认识较为统一，而对小管径垂直管仍未有清晰的认识。在管径25~100 mm范围对垂直管的完全携带点进行了实验，探究了小管径垂直管的完全携带点预报方法。实验结果表明在小管径范围，垂直管完全携带点对应的临界表观气速随管径增大而升高，但气相Wallis数随管径增大而减小，说明Wallis数过度关联了管径对临界表观气速的影响。基于气相Kutateladze数和无量纲气相黏性，对小管径垂直管提出了新的完全携带点预报模型和相应实验关联式。     

Compromising system and user interests in shelter location and evacuation planning

Traffic management during an evacuation and the decision of where to locate the shelters are of critical importance to the performance of an evacuation plan. From the evacuation management authority’s point of view, the desirable goal is to minimize the total evacuation time by computing a system optimum (SO). However, evacuees may not be willing to take long routes enforced on them by a SO solution; but they may consent to taking routes with lengths not longer than the shortest path to the nearest shelter site by more than a tolerable factor. We develop a model that optimally locates shelters and assigns evacuees to the nearest shelter sites by assigning them to shortest paths, shortest and nearest with a given degree of tolerance, so that the total evacuation time is minimized. As the travel time on a road segment is often modeled as a nonlinear function of the flow on the segment, the resulting model is a nonlinear mixed integer programming model. We develop a solution method that can handle practical size problems using second order cone programming techniques. Using our model, we investigate the importance of the number and locations of shelter sites and the trade-off between efficiency and fairness.