The Origins and Early Implementation of the Magnuson-Stevens Fishery Conservation and Management Act of 1976

The Magnuson-Stevens Fishery Management and Conservation Act, enacted in 1974, is the primary federal fishery management legislation in the United States. The political impetus that led to enactment was the extensive foreign fish off U.S. shores that expanded following World War II and the failure of international negotiations to prevent the decline in many fisheries relied upon by domestic fishers. In Congress, there was uncertainty as to whether a comprehensive management program would be created along with a unilateral extension of fishery management jurisdiction out to 200 nautical miles. The delay in agreement over a new United Nations Law of the Sea Treaty and resolution of the extent of coastal nation jurisdiction over fisheries culminated in enactment of the legislation sponsored by Senator Warren Magnuson, a Democrat from Washington State, and Senator Ted Stevens, a Republican from the State of Alaska.     

Dynamic hardening behaviors of various marine structural steels considering dependencies on strain rate and temperature

This paper presents a new formula for prediction of the dynamic hardening effect for various marine structural steels, considering dependencies on the strain rates and temperatures. Dynamic tensile tests are carried out for three kinds of marine steels, 2W50, EH36, and DH36, changing the steel layer in the thickness direction, the strain rates, and temperatures. Considering two thickness layers at the middle and surface, five strain rate levels of 0.001/s, 1/s, 10/s, 100/s, and 200/s, three temperature levels of LT (−40 °C), RT, and HT (200 °C), and two repetitions, the total number of tests is 180. Dynamic hardening is clearly seen at LT and RT regardless of the material type, while dynamic strain aging occurs at HT, leads to negative strain rate sensitivity, and thus elevates the quasi-static flow stress above the dynamic flow stress to a certain strain rate. Dynamic hardening factors (DHFs) are derived as a function of the proof strains of 0.05, 0.10, and 0.15 according to each material type and temperature level. A new formula to determine the material constant D of Cowper–Symonds constitutive equation is developed. The correctness of the proposed formula is verified through comparison with test flow stress curves and reference test data in large plastic strain and high strain rate ranges.     

钢筋混凝土空心板梁疲劳损伤试验研究

为获取钢筋混凝土空心板梁的疲劳损伤发展规律,通过对1片试验梁的静载试验测得试验梁的极限承载力,以此作为疲劳试验加载幅值取值依据,对5片试验梁进行等幅疲劳加载试验.试验表明,试验梁呈现出明显的疲劳损伤三阶段(即快速发展、稳定和破坏)规律.接近疲劳破坏时除1至2条主裂缝继续扩展外,其余裂缝停止增长并逐渐闭合,最终在主裂缝处疲劳断裂.试验梁的挠度发展、钢筋与混凝土的应变发展增量在疲劳循环初期增长比较显著;随着疲劳荷载循环次数的增加,增长速率趋缓而进入相对稳定发展阶段;临近破坏时又发生较大幅度的增长.     

基于蠕变效应的隧道衬砌结构耐久性研究

以佛岭隧道工程为依托,通过蠕变试验得到围岩和衬砌相应的力学特性参数,并对佛岭隧道在开挖后及使用期间的应力-应变规律给出具体求解,经计算可知,佛岭隧道在使用若干年后,支护的径向力和相互作用力都趋向于0.38 MPa。结论对隧道衬砌结构耐久性的研究具有一定的参考意义。     

边坡滚石破坏及防护技术研究

为了有效防治高速公路边坡发生岩石滚石破坏,基于能量守恒定律建立了边坡滚石飞落模型,综合考虑边坡坡型、地面摩擦因数等因素推导了岩石滚落轨迹方程,并根据所建立的模型计算出滚石水平运动距离及滚石在防护栏处的撞击能,从而提出合理的道路防护方式.研究结果表明:滚石撞击坡面后的水平运动距离小于撞击点到公路路缘的水平距离,滚石飞落至地面的撞击能为142 kJ,设计采用型号为AXI-015(防护能级为150 kJ)的被动防护网,可对高速公路坡面滚石灾害进行有效防护.     

车载娱乐总成的静态电流分析

本文对车载娱乐总成的静态电流进行测试,找出其在室温、低温、高温下的分布规律,为车载娱乐总成生产厂家提供优化静态电流的思路。     

上海市防汛能力建设调查及评价

上海位于长江入海口,低洼的地势使得上海遭受台风、暴雨、高潮、洪水(俗称“四碰头”)的袭击后易成灾,多年来上海已建设抵御灾害的防汛体系,且发挥了积极的作用。在对上海防汛能力建设体系开展调查的基础上,分析存在问题和不足。同时,结合科学的层次分析法理论构建评价指标体系,为后续防汛能力建设的进一步优化提供依据。     

对海事依法行政有关问题的思考

中国的改革开放是一场史无前例的“摸着石头过河”的大试验。依法行政也有“摸着石头过河”的感觉。马列主义是关于实践的科学,从实践的角度来认识与思考依法行政,对提高依法行政水平更具有现实性。     

对船舶污染损害侵权责任及索赔主体问题的探讨

船舶污染事故是造成海洋环境污染损害的主要原因之一,建立完善的船舶污染损害索赔机制,保证受损方获得及时的赔偿,是恢复海洋环境、维护受害者利益所必须的。文中从民法的基本原理出发,对国家海域所有权、海域使用权等进行了论述,并按照民事侵权责任的承担原则,对索赔权利主体的确定等问题进行了探讨。     

浅谈公路路政执法和谐机制的构建

构建公路路政执法和谐机制，是建设和谐公路的重要内容。文章分析了当前公路路政执法存在的不和谐现象及原因，提出了构建公路路政执法和谐机制的对策与措施。