CRTSⅢ型减振板式轨道垫层刚度限值研究

为研究CRTSⅢ型减振板式轨道减振垫层刚度对自密实混凝土耐久性的影响,应用弹性地基梁-实体有限元模型,以减振垫刚度限值为研究对象,考虑列车荷载与正温度梯度共同作用,计算不同垫层刚度下自密实混凝土的拉应力、裂纹分布及宽度、耐久性损伤度。结果表明,随减振垫层刚度减小,自密实混凝土层拉应力、裂纹数量、裂纹宽度及耐久性相对损伤度均逐渐增大;依据自密实混凝土层耐久性要求,得到减振垫层的面刚度下限值为20 MPa/m。     

汽车车身焊装过程小样本采样的评价极限

对汽车车身焊装过程中小样本采样的评价极限进行了研究。根据实际车身焊装过程中质量评价的需要,建立了基于蒙特卡罗方法的小样本采样评价极限确定方法,获得了车身焊装过程中小样本采样误差随样本量变化的曲线。在此误差曲线的基础上,以实际评价过程能够接受的置信程度为标准,确定小样本方法的评价极限,取得了很好的效果。     

Diatom stratigraphy and long-term dissolved silica concentrations in the Baltic Sea

In many parts of the world coastal waters with anthropogenic eutrophication have experienced a gradual depletion of dissolved silica (DSi) stocks. This could put pressure on spring bloom diatom populations, e.g. by limiting the intensity of blooms or by causing shifts in species composition. In addition, eutrophication driven enhanced diatom growth is responsible for the redistribution of DSi from the water phase to the sediments, and changes in the growth conditions may be reflected in the sediment diatom stratigraphy.To test for changes in diatom communities we have analyzed four sediment cores from the Baltic Sea covering approximately the last 100 years. The sediment cores originate from the western Gulf of Finland, the Kattegat, the Baltic Proper and the Gulf of Riga. Three out of the four cores reveal only minor changes in composition of diatom assemblages, while the Gulf of Riga core contains major changes, occurring after the second World War. This area is set apart from the other Baltic Sea basins by a high frequency of low after spring bloom DSi concentrations (< 2 µmol L^− 1) during a relatively well defined time period from 1991–1998. In 1991 to 1993 a rapid decline of DSi spring concentrations and winter stocks (down to 5 µmol L^− 1) in the Gulf was preceded by exceptionally intense diatom spring blooms dominated by the heavily silicified species Thalassiosira baltica (1991–1992; up to 5.5 mg ww L^− 1). T. baltica has been the principal spring bloom diatom in the Gulf of Riga since records began in 1975. DSi consumption and biomass yield experiments with cultured T. baltica suggest that intense blooms can potentially exhaust the DSi stock of the water column and exceed the annual Si dissolution in the Gulf of Riga. The phytoplankton time series reveals another exceptional T. baltica bloom period in 1981–1983 (up to 8 mg L^− 1), which, however, took place before the regular DSi measurements. These periods may be reflected in the conspicuous accumulation of T. baltica frustules in the sediment core corresponding to ca. 1975–1985.     

论我国海事赔偿责任限制制度

海事赔偿责任限制是我国《海商法》中的一项重要法律制度。其立法及施行涉及到国内法和外国法的法律适用和法律冲突。如何看待和处理这些问题,将有助于对这一海事领域所特有的制度的理解。此文就我国海事赔偿责任限制制度中存在的一些问题作了探讨。     

拱桥极限跨径研究

以拱肋材料的强度为限定条件，研究恒载下分别以抛物线、悬链线作为合理拱轴线时拱桥的极限跨径。并以此为基础，就极限跨径下拱桥的最佳矢跨比范围进行讨论。     

试论民事诉讼举证责任的时限

当今我国事诉讼举证制度中的矛盾和弊端已经影响了法律的严肃性和权威性,为了适应改革开发和经济发展的需要,将我国的诉讼制度与国际通行诉讼规则接轨,禁止滥用诉权和自由心证,提高法院的公信力和办 案效率,必须尽快在立法上对举证时限制度作出规定。     

天山公路泥石流形成机理参数的计算方法

泥石流是天山公路的主要地质灾害之一,天山公路泥石流的机理研究主要来自对区域泥石流的研究。研究工作以点面相结合为基础,通过对天山公路泥石流3个基本形成条件(即松散固体堆积物,水源和地形)的分析,提出了天气形势、暴雨强度、前期降雨、滑坡活动、土体含水等因素与泥石流暴发时间、规模大小、流体性质之间的关系,建立了部分相关公式。从而进行探讨和分析。     

重载交通条件下高速公路沥青路面设计

介绍重载交通对路面的影响及重载交通条件下设计上的局限;结合临吉高速公路的路面设计,列举典型路面结构。     

浅议桥梁钻孔灌注桩缺陷成因及防治措施

梁钻孔灌注桩缺陷往往是由于施工工艺不合理引起,因此必须对桩基工程的施工工艺、质量保证措施进行严格的控制。     

常规急滩整治方法在库区急滩治理中的局限性

三峡-葛洲坝两坝间库区急滩多为峡谷型洪水急滩,采用常规的扩大泄水断面等方法进行整治,不仅工程量大,废方多,也难以达到理想的治理效果,而且易引发滑坡等地质灾害。以三峡-葛洲坝两坝间水田角、喜滩两处急滩为例,对库区峡谷型洪水急滩的滩性特点及运用急滩常规整治方法进行治理时存在的局限性进行分析研究。