Pulsar radio emission

Radio emission by pulsars is calculated from first principles. In an almost current-free magnetosphere, the two charged components (of the unsteadily escaping pair plasma) have different (and varying) bulk Lorentz factors. Curvature radiation emitted by the more energetic component is thus locally coherent, (so-called antenna mechanism). Strong enough seed signals cause the relativistically streaming charges to enhance their radiation, via an induced drift that can largely exceed the curvature drift. This amplification mechanism is similar to - but different from - that of a maser; we call it a MAIDER. Maximal amplification occurs at an (emission) altitude where the two components have sufficiently separated in energy though not yet separated too strongly in space.     

中国大修侧钻技术的发展与创新

在回顾我国大修侧钻技术发展历史的基础上，立足于大修偶侧钻技术现状，展望了21世纪我国修井技术的发展趋势。     

关于地下车库(位)产权的思考

近年来,随着我国经济建设的高速发展,私家车的拥有量在急速增加,同时,现代化生活和集约有效利用土地的要求使地下车库(位)(以下统称“地下车位”)的建设越来越多。根据国家统计局《中华人民共和国2005年国民经济和社会发展统计公报》公布的统计数字,2005年全国商品房竣工建筑面积48793万m2,按照每套房子100m2测算,共计488万套,假设房屋与车位配备比为5∶1,则车位数量将为97.6万个。地下车位的产权不清,不仅国有土地资产流失严重,而且购买者的权益得不到应有的保护,全国各地因此引起的纠纷甚至诉讼频发。1地下车位产权不清车位的产权到底归谁…     

Optimum design and experimental study of multiple tuned mass dampers with limited stroke

This paper develops a two‐stage optimum design procedure for multiple tuned mass dampers (MTMD) to reduce structural dynamic responses with the limitation of MTMD's stroke. A new performance index, which is a linear combination of structural response ratio and MTMD stroke ratio by a weighting factor α, is proposed; α is in the range from 0 to 1.0. The larger the α, the more important the stroke. The case of α=1.0 indicates that MTMD is locked. The analytical results show that the MTMD's stroke can be significantly suppressed with little sacrifice of structural control effectiveness when an appropriate α is selected. To verify the design algorithm, a 360 kg‐MTMD composed of five TMD units arranged in parallel was fabricated. Shaking table tests of a large‐scale three‐story building with and without the MTMD under earthquake excitations were conducted at the National Center for Research on Earthquake Engineering (NCREE) in Taiwan. The experimental results show that MTMD is not only effective in mitigating the building responses but also is successful in suppressing its stroke. Copyright © 2010 John Wiley & Sons, Ltd.     

流体 花岗岩 金矿

流体地质研究是当代地学研究中的重要前沿课题，已成为发展地质科学、建立新的知识体系的一个主要支柱和知识生长点。本文阐述了当今国内外流体的研究现状、发展水平、流体的涵义、性质、研究方法和研究重点及其与板块构造、变质作用、岩浆作用、成矿作用、成矿作用的重要意义。流体地质为地质科学提出了许多新的研究机会和挑战。该文在简要评述当今花岗岩研究现状的基础上，对花岗岩与金矿的关系进行了深入的讨论，指出了不同成因类型的花岗岩与金矿有着完全不同的关系。人们所说的花岗岩与金矿关系多数情况下应考虑是流体作用的结果。最后指出加强流体地质研究对提高河南地质与金矿的研究水平具有十分重要的实际意义和理论意义。     

Hydroacoustic estimates of fish biomass and spatial distributions in shallow lakes

We conducted acoustical surveys with a horizontal beam transducer to detect fish and with a vertical beam transducer to detect depth and macrophytes in two typical shallow lakes along the middle and lower reaches of the Changjiang(Yangtze) River in November 2013. Both lakes are subject to active fish management with annual stocking and removal of large fish. The purpose of the study was to compare hydroacoustic horizontal beam estimates with fish landings. The preliminary results show that the fish distribution patterns dif fered in the two lakes and were af fected by water depth and macrophyte coverage. The hydroacoustically estimated fish biomass matched the commercial catch very well in Niushan Lake, but it was two times higher in Kuilei Lake. However, acoustic estimates included all fish, whereas the catch included only fish 45 cm(smaller ones were released). We were unable to determine the proper regression between acoustic target strength and fish length for the dominant fish species in the two lakes.     

Pb distribution and translocation in Jiaozhou Bay

The trends of distribution, translocation and seasonal change of heavy metal Pb were studied based on the surface and bottom water sampling in Jiaozhou Bay in 1979, and compared with those in 1990＇s. The results showed that the source of Pb in the bay was from wastewater and sewage in the east of Jiaozhou Bay from ocean vessels. Pb concentration was higher in spring and lower in summer and autumn, and remained stable through sedimentation in the bottom layer. The overall water quality was good in 1970＇s. Compared with the environmental monitoring data of 1995-1999, Pb pollution had become serious. Therefore, more efforts should be made to protect the bay from Pb pollution.     

1980—2020年中国九大流域蒸散发及其组分时空评估

蒸散发是地表陆气水分交换的纽带,准确量化蒸散发的时空演变格局对于水资源规划与管理至关重要。本文基于GLEAM模型的蒸散发及其组分数据集,借助7个通量观测站数据、120个流域的流域水量平衡及PML_V2蒸散发产品,在中国九大流域系统评估了GLEAM-ET产品,分析了植被恢复背景下,蒸散发（ET）及其组分（植被蒸腾Ec,截留蒸发Ei,土壤蒸发Es）在1980—2020年的时空演变格局。本文主要得到以下结论：① GLEAM-ET产品在中国九大流域具有较好的适用性,其性能与气候类型有关,干旱区效果优于湿润区。此外,GLEAM与PML_V2模型在九大流域相关性较好（R>0.7）,分布格局与变化趋势整体保持一致。② 全国尺度上,ET均值为416.88 mm,增长速率为1.21 mm/a。Ec与ET均呈自东南向西北递减的分布格局,而Es与其相反。Ec、ET在九大流域均呈显著增加趋势（p<0.001）。Ei、Es在季风区流域分别呈显著增加和显著减小趋势;在内陆区流域呈不显著减小（p>0.05）和显著增加趋势。③在植被恢复背景下,ET组分比例发生了变化。Ec占比变化存在南北差异,南方流域Ec占比均减小,北方流域均增加。Ei占比在各流域均增加,Es占比均减小。黄河流域ET组分对植被恢复的响应最为明显,Ec占比增加了5.21%,Es占比减小了5.56%。     

基于深度学习的钨钼找矿靶区预测方法研究

随着矿产勘查工作由浅部矿向深部隐伏矿、由易识别矿向难识别矿发展,找矿难度日益增大,地质专家越来越重视新理论、新方法、新技术的应用。深度学习作为人工智能的前沿领域/技术,对于实现矿产资源预测“智能化预测评价”具有得天独厚的优势。本文以陕西省镇安县西部钨钼矿集区单元素化探异常原始数据为基础,提出了基于深度学习的钨钼矿产评价方法。该方法以归一化地球化学数据作为模型训练数据,通过深度学习中深度自编码网络方法实现异常值提取进而识别重点成矿有利地段,实现矿产资源找矿远景区定性预测。研究结果表明,在对957条单元素化探异常原始数据分类且做好模型标签后,整个过程在计算机的“黑盒子”中自动完成学习和预测,相较于传统预测研究方法,本文方法具有自动化程度高和客观性强的特征。此外,本文利用已知矿点构建训练数据集,采用随机森林方法对预测区进行矿产资源找矿靶区预测圈定,为进一步缩小找矿靶区范围提供科学依据。