中国数字地震台网(CDSN)和IMS/PS台阵的监测定位能力评估   总被引：12，自引：6，他引：6  

郝春月  郑重  郭燕平  周公威  张爽 《地震地磁观测与研究》2006,27(2):56-63

根据近震震级(ML)和远震震级(Ms)公式,估算了中国数字地震台网(CDSN)对近震和远震的定位能力,并把IMS／PS台阵(海拉尔台阵与兰州台阵)作为加强台站,与CDSN一并估算了其联合定位能力,此后,对两个定位能力结果做了比较。  相似文献   

敦煌-格尔木铁路沿线风动力环境特征     

鱼燕萍  张克存  安志山  张余 《中国沙漠》2020,40(1):41-48

敦煌-格尔木铁路沿线地形复杂、起沙因素多变、沙源丰富,沙害问题日益严重。目前对其风沙活动规律还未有研究,不利于防沙工作的开展。为此,通过对自北向南的5个观测点（S1、S2、S3、S4、S5）风速和风向的观测、计算和分析,利用平均风速、起沙风况及输沙势对敦格铁路沿线的风动力环境特征进行研究。结果表明：S5、S4和S3的风况对铁路风沙灾害防治意义较大。S5年平均风速、起沙风频率和输沙势最大,春季风沙活动最为强烈,且风向单一、风力强劲,风沙运动方向基本与铁路垂直,沙粒易在铁路附近堆积。S4夏季风沙活动最为强烈;S3春季风沙活动最为强烈,且风向单一,S4和S3的风沙运动方向与铁路夹角小于90°,附近沙源广阔,铁路易受风沙侵蚀,阻碍交通运营。  相似文献   

乡土资源在高中地理教学中的应用尝试     

苏燕萍  郭国金 《地理教学》2020,(1):46-47,26

乡土资源融入高中地理教学,不仅能够激发学生的学习兴趣,培养学生的综合思维,还能提高学生的地理实践能力。结合《普通高中地理课程标准(2017年版)》的相关要求,文章尝试性地利用乡土资源设计高中地理教学案例、编制地理试题和开展地理实践活动等。  相似文献   

Enhanced a novel β-agarase production in recombinant Escherichia coli BL21(DE3) through induction mode optimization and glycerol feeding strategy     

CHAN Zhuhua  CHEN Xinglin  HOU Yanping  GAO Boliang  ZHAO Chungui  YANG Suping  ZENG Runying 《海洋学报(英文版)》2018,(2)

Agarases are hydrolytic enzymes that act on the hydrolysis of agar and have a broad range of applications in food,cosmetics and pharmaceutical industries. In this study, a glycerol feeding strategy based on induction mode optimization for high cell density and β-agarase production was established, which could effectively control acetate yield. First, exponential feeding strategy of glycerol with different overall specific growth rates(μ) was applied in the pre-induction phase. The results showed that the low μ(μ=0.2) was suggested to be the optimal for cell growth and β-agarase production. Second, the effects of induction temperature and the inducer concentration on cell growth and β-agarase production were investigated in the post-induction phase. When induced by isopropyl-β-d-thiogalactoside(IPTG), the strategy of 0.8 mmol/L IPTG induction at 20℃ was found to be optimal for β-agarase production. When cultivation was induced by continuous lactose feeding strategy of 1.0 g/(L·h), the β-agarase activity reached 112.5 U/mL, which represented the highest β-agarase production to date.Furthermore, the β-agarase was capable of degrading G. lemaneiformis powder directly to produce neoagarooligosaccharide, and the hydrolysates were neoagarotetraose(NA4) and neoagarohexaose(NA6). The overall research may be useful for the industrial production and application of β-agarase.  相似文献   

基于DEA-TOBIT模型的我国港口业 上市公司经营效率研究          下载免费PDF全文

郭鹏  温艳萍 《海洋开发与管理》2019,36(1):107-113

文章利用DEA-TOBIT两阶段法,对我国17家港口业上市公司2011—2016年经营效率及影响因素进行了测算和分析,并运用Malmquist指数对我国港口业上市公司的经营效率变化进行动态分析。研究结果表明:从静态效率分析,17家港口上市公司综合效率值相对较高,但维持在产出不变的情况下,港口公司投入仍有相对的节能空间;从动态效率上看,在研究期内17家港口上市公司的全要素生产率总体呈下降趋势,技术水平下降和规模效率的降低是造成全要素生产率降低的主要原因;从效率影响因素研究来看,总资产周转率、资产收益率、股权集中度和上市时间与港口经营效率呈正相关,企业的资产负债率对港口经营效率呈负向影响,企业的规模大小对港口经营效率的影响不明显。最后,根据实证结果,提出了科学合理的融资渠道组合,提高港口企业资产周转率;不断提升企业自身管理水平,科学控制企业规模;积极把握时代发展需求,加大企业技术创新,实现港口创新型驱动发展;大力建设港口组合,合作共享,协调发展等对策建议。  相似文献   

自然资源管理改革基本逻辑下海洋自然资源 年度利用计划的思考          下载免费PDF全文

刘大海  李彦平  李晓璇  马雪健 《海洋开发与管理》2019,36(1):23-29

重构自然资源管理体系的重点并不在于直接干预和调整资源配置的结果,而在于优化重塑自然资源配置制度和手段。自然资源管理改革在机构方面基本实现了"两统一",并在海域管理方面取消了过去的围填海年度计划。文章以此为背景,梳理了自然资源管理制度重构的基本逻辑,以围填海为例解析了自然资源管理模式调整思路。基于以上提出海洋自然资源利用年度计划的初步构想,包括将海洋自然资源年度利用计划作为国土空间用途管制中的基础性制度。并提出政策建议:坚持陆海统筹,加强计划管理对海洋资源开发、保护和修复的约束与引导;探索"总量不变、盘活存量"的海洋空间资源供给思路;完善围填海"总量控制、中央统筹"的管理流程;聚焦解决围填海历史遗留问题;加强自然资源法治建设。  相似文献   

Size-fractionated uranium isotopes in surface waters in the Jiulong Estuary in China   总被引：1，自引：1，他引：0  

L&#; E  ZHANG Lei  CHEN Min  QIU Yusheng  XING N  YANG Weifeng  LI Yanping  HUANG Yipu 《海洋学报(英文版)》2008,27(1):29-41

Surface water was collected from the Jiulong Estuary for determination of activity concentrations of uranium isotopes in different size fractions, namely, greater than 53, 10 -53, 2 - 10, 0.4 -2 μm, 10 000 u -0.4 μm and less than 10 000 u fractions by microfihration and cross-flow uhrafiltration technologies. Results indicated that most of the dissolved uranium （ 〈 0.4 μm） exis- ted in the low molecular mass fraction （ 〈 10 000 u）, and the colloidal uranium-238 （10 000 u -0.4 μm） only contributed less than 1% of the dissolved uranium-238. The fractions of colloidal uranium in the dissolved phases decreased with the increasing sa- linity. A positive linear relationship between uranium-238 activities and salinities was observed for the dissolved, colloidal and low molecular mass fractions, indicating a conservative behavior of uranium in the Jiulong Estuary. In the particulate phases （ 〉 0.4 μm）, the partitioning of uranium isotopes among different size fractions was controlled by the partitioning of particle concentrations. In the regions with salinities below 20, the partitioning of uranium-238 among different size fractions was as follows： 10 - 53 μm 〉 2 - 10 μm 〉 0.4 - 2 μm greater than above 53 μm. However, the order at the offshore station with salinities above 30 changed as follows ： 0.4 - 2 μm 〉 10 - 53 μm 〉 2 - 10 μm greater than above 53 μm. The fraction of the 0.4 - 2 μm particles increased at the offshore station, suggesting the increased contribution of the authigenic uranium. The activity ratio of uranium-234 to uranium-238 in the dissolved phases, including the low molecular mass fraction and the colloidal fraction, was larger than unity, showing the occurrence of excess uranium-234. In contrast, the activity ratio of uranium-234 to uranium-238 in all size fractions of the particulate phase was close to the equilibrium value （1.0）. The observed different values of the activity ratio of uranium-234 to uranium-238 in the dissolved phase and the partic  相似文献   

山东温泉旅游资源分析及科学发展思考   总被引：1，自引：0，他引：1       下载免费PDF全文

李宇荣  王艳平 《山东国土资源》2008,24(3):35-38

山东省温泉资源分布广泛、储量大,利用历史十分悠久,在温泉资源开发应用过程中,应根据其分布、类型、开发利用现状,并结合国内外的科技成果而进行科学开发与综合利用,建设既有地方民俗文化特色又与国际接轨的可持续发展模式。  相似文献   

Semi-active model predictive control for 3rd generation benchmark problem using smart dampers     

颜桂云  孙炳楠  吕艳平 《地震工程与工程振动(英文版)》2007,6(3):307-315

A semi-active strategy for model predictive control (MPC), in which magneto-rheological dampers are used as an actuator, is presented for use in reducing the nonlinear seismic response of high-rise buildings. A multi-step predictive model is developed to estimate the seismic performance of high-rise buildings, taking into account of the effects of nonlinearity, time-variability, model mismatching, and disturbances and uncertainty of controlled system parameters by the predicted error feedback in the multi-step predictive model. Based on the predictive model, a Kalman-Bucy observer suitable for semi-active strategy is proposed to estimate the state vector from the acceleration and semi-active control force feedback. The main advantage of the proposed strategy is its inherent stability, simplicity, on-line real-time operation, and the ability to handle nonlinearity, uncertainty, and time-variability properties of structures. Numerical simulation of the nonlinear seismic responses of a controlled 20-story benchmark building is carried out, and the simulation results are compared to those of other control systems. The results show that the developed semi-active strategy can efficiently reduce the nonlinear seismic response of high-rise buildings.  相似文献   

Virgo星系团的Virial质量和运动学分析     

赵君亮  潘容士  何燕萍 《中国天文和天体物理学报》1992,(2)

本文利用由Binggeli、Sandage和Tammann提供的Virgo团天区星系视向速度所确定的6°核区域的352个成员星系,得出团的Virial质量为μv=2.7×10~(14)μ。总光度L_B=2.0×10~(12)L,质光比μv/L_B=136,以及光度质量μ_L=4.1×10~(13)μ,Virgo团有着和Coma团类似的速度弥散度轮廓,近团中心部分的星系速度弥散度有减小的趋势。团星系呈现明显的形态分层,早型星系较之晚型星系明显向团中心聚集,速度弥散度较小(615:827公里·秒~(-1))。分析表明,Virgo团所经历的动力学演化过程很短,质量分层效应很不显著,是一个年轻的不规则星系团。  相似文献