车辆驾驶室减振降噪分析与结构设计

利用薄板理论建立了汽车驾驶室壁板的微分振动方程。对驾驶室进行了试验模态分析,得出固有频率和基本振型变化。发现顶板和后壁板振动最大,采用辛几何法计算出了驾驶室顶板和后壁板的固有频率,其值与试验值基本一致,对驾驶室后壁板和顶板分别采用敷贴阻尼材料和加筋板的降噪方法,利用声辐射理论,对改进后的驾驶室降噪效果进行了数值模拟,结果表明,壁板固有频率处的辐射功率和辐射声压级最大,与理论分析相符,并且改进后的驾驶室内部噪声明显降低。     

Eclogites in the interior of the Tibetan Plateau and their geodynamic implications

Eclogites have been recently reported in the interior of the Tibetan Plateau, including in the central Qiangtang metamorphic belt, in the Basu metamorphic massif of the eastern Bangong-Nujiang suture zone, and at Songdo and Pengco in the eastern Lhasa terrane. Some typical ultrahigh-pressure （UHP） metamorphic phenomena, e.g., garnet exsolution from clinopyroxene, were documented in the Basu and Pengco eclogites. The UHP metamorphism in the interior of the Tibetan Plateau marked by these eclogites generally took place in the Early Mesozoic. Along with exhumation of these eclogites, （post-） collision-related magmatism extensively occurred around the central Qiangtang belt, the eastern Bangong-Nujiang suture zone, and the eastern Lhasa terrane. The occurrence of these Early Mesozoic eclogites manifests an out-of-sequence evolution of the Tethys, and they could be a product of diachronous collision between the eastern Qiangtang terrane and the irregular continental margin of the united western Qiangtang-Lhasa plate, along the linked eastern Bangong-Nujiang-central Qiangtang zone. The collision-related magmatic rocks could have been originated from lithospheric thickening, melting, or detachment due to the collision. The presence of UHP metamorphic rocks in central Qiangtang and Basu implies likely continental deep-subduction, and the denudation of these two metamorphic zones could have served as the source of the Triassic turbidites in the Songpan-Garze complex and the Jurassic turbidites in the western Bangong-Nujiang zone, respectively. However, studies of the eclogites in the interior of the Tibetan Plateau just began, and many principal aspects still remain to be explored, such as their distributions, typical lithologies and minerals, temperature-pressure conditions, timing of formation and exhumation, protoliths and tectonic setting, and relationship with the evolution of the Tethys and large-scale basins in Tibet.     

滇中及邻区大地构造演化─运动特征

滇中及其邻区的大地构造演化运动经历了原陆壳活动阶段、原陆壳“稳定”阶段、地槽、地台和地洼５个阶段,留下了相应的构造层．前地槽构造层包括活动和稳定２种类型,具有面状分布的特征,代表陆壳演化初期刚性较低的地壳特点．地槽构造层以大红山群、昆阳群和澄江组为代表,但邻区出现分异现象．地台构造层的特征表明最迟在寒武纪,本区壳体接合成为一个稳定的整体,但从奥陶纪开始古地台边缘出现陆缘扩张现象,形成局部扩张槽．地洼阶段具有中亚壳体和东亚壳体过渡性特点,地洼阶段开始的时间与东亚壳体的相同,而激烈期时间与中亚壳体的相同．通过构造层特征的分析,认为滇中及其邻区壳体成长经历了接合、同化、分异、同化的过程．     

Growth and reworking of cratonic lithosphere

To study the thinning of cratonic lithosphere in North China has been the hot subject of basic research in the fields of solid earth science in China. This paper presents an overview on the formation and evolution of continental crust, and outlines the mechanisms of forming the lithospheric mantle. It is suggested that the thinning of cratonic lithosphere principally proceeds in two ways, one by subduction erosion （e.g., North China）, and the other by a combination of subduction erosion and underplating degistion （e.g., Yangtze）.     

地球系统科学与可持续发展(Ⅴ)——理论基础概述

地球系统科学是可持续发展战略的科学基础,它跨越一系列自然与社会科学。本文将两者融为一体进行系统研究,讨论了地球系统科学与可持续发展研究的意义及其内涵,并初步提出了理论体系。同时,本文以地球系统科学为指导思想,对大地构造学进行了深入、系统地总结、分析和研究。在此基础上,尝试提出了地球系统科学统一构造理论的学术观点。取得八点结论     

推覆构造的控矿成矿规律——以武当山推覆构造为例

通过对武当山推覆构造与成矿关系的研究,认为在推覆构造中的固体矿产主要分布于推覆体变形强烈的两端和推覆构造的强应变带内。     

Decoupling of surface and subsurface sutures in the Dabie orogen and a continent-collisional lithospheric-wedging model：Sr-Nd-Pb isotopic evidences of Mesozoic igneous rocks in eastern China

Based on the distribution of UHPM rocks on the surface in Sulu terrane, the surface suture between the NCB and SCB should be located along the Wulian fault (see Fig. 1, S1). However, based on the aeromagnetic data of eastern China, Li[1] first indicated that the subsurface suture between the NCB and SCB in the region east of the Tan-Lu fault should be located to the east of Nanjing City (see Fig. 1, S2), which south displaced about 400 km from the surface suture. This is contradicto…     

长江形成的大地构造背景与沿江带的环境效应

长江上游金沙江段的展布形态为一向NE凸出的弧形,宜宾-宜昌段主要为向NW凸出的弧形;中游近似于"S”形;而下游则是向N凸出的弧形.这一特殊的自然地理面貌严格受青藏地块、秦祁昆地块和扬子板块的构造格局控制,是特提斯构造系统和太平洋构造系统及其二者复合作用的结果.沿长江地带的地震活动是上述两大构造系统下,新构造运动所致,在二者的接合部位地震活动最强烈.长江沿岸的地质灾害严格受岸坡的岩石类型、结构面规模以及产状等因素的影响.因此,长江的形成和沿江带的环境效应与大地构造背景密切相关.     

黔西南赵家坪矿带地层中汞金地球化学研究

通过对地层中汞、金的某些沉积作用和地球化学特征的研究,认为赵家坪矿带内各地层中的汞、金曾参加了同生沉积作用。由于黔西南普遍存在着玄武岩喷发对地层中汞金含量在时间上和空间上的直接和间接控制作用,使地层中的汞、金含量达到了初始富集,即形成了矿源层。再经构造热液改造矿源层而成矿。     

一种实用车牌定位算法及实现

提出了结合空域拓扑结构和频域特征的车牌定位实用算法。在空域上，首先对原始照片进行预处理，包括灰度拉伸处理从而均衡光照影响，有利于增强算法的鲁棒性；然后对前面处理结果进行形态学梯度变换从而加强车牌文字区域的线状结构，有利于突出文字的频率特征。在频域上，利用车牌文字的横向频率特征，按照一定稠密度条件筛选水平象素，得到若干相对稠密的水平点集。接着在空域上对频域处理结果进行几何归并、拓扑筛选。最后利用车牌本身特点提出以一种快速倾斜纠正方法，并经过投影过滤，从而实现车牌区域快速准确定位。