Global Plate Motions and Their Impact on the Earth's Surface Area Change

Based on their Euler poles,we calculated the relative velocities between every two plates in the typical global plate motion models,respectively,and estimated the area change along these boundaries. In our calculations,plates on both sides accommodated area changes depending on the boundary types: extensional, convergent or transform, so we can estimate area change of each plate and then globally. Our preliminary results show that the area of the southern hemisphere increased while that of the northern hemisphere decreased over the past 1 million years,and global area has increased by 26,000km2 to 36,000km2,which corresponds to the 160m～250m increment on the Earth's radius if all these area increments are attributed to Earth's expansion. Taking the NUVEL-1 model as an example,of the 14 plates in this model,11 are decreasing,but the global area has increased because of the larger increment amount from Africa,North America and Antarctica. Finally,we also discussed factors affecting the global area change such as subduction zone retreating and back-arc spreading.     

Dual inexact fuzzy chance-constrained programming for planning waste management systems

This study develops a dual inexact fuzzy chance-constrained programming (DIFCCP) method for planning municipal solid waste (MSW) management systems. The concept of random boundary interval (RBI) is introduced to address the high uncertain parameters in the studied system. Fuzzy flexible programming and chance-constrained programming are also introduced to take into account the uncertainties of RBIs and various uncertainties in MSW management system. Compared with the existing methods, the developed method could deal with the uncertainty without simplification and thus is more robust. Moreover, the potential system-failure risks in MSW management system due to the existing uncertainties could be quantified by means of violation levels and satisfaction levels in DIFCCP. The developed method then is applied to a MSW management system. The obtained solutions could be used for generating efficient management schemes. The values of violation and satisfaction levels could help decision makers understand the tradeoffs between system cost and system-failure risk, and identify desired strategy according to the practical economic and environmental situation.     

地裂缝场地建筑结构动力响应特征及抗震设防研究

为研究地震作用下地裂缝场地建筑结构的动力响应特征,以西安地裂缝场地为研究背景,分别考虑独立基础、片筏基础、桩基础和桩筏基础上的框架结构,对结构峰值加速度、层间位移等动力响应特征及其影响因素和影响规律进行系统研究。研究结果表明：(1)地裂缝附近场地上的结构加速度响应和层间位移响应具有明显的放大效应,动力响应峰值随着距地裂缝距离的增大逐渐减小,最终趋于稳定,放大效应的影响范围约为24 m,此范围内的结构需提高抗震设防水平;(2)结构的峰值加速度随层高的增大而增大,整体呈现出“S”形,层间位移角随层高的增大先增大后减小,二者均表现出明显的“上盘效应”,即上盘结构响应强于下盘,且随着输入地震动强度的增大,上、下盘结构动力响应差异进一步扩大,上盘效应愈发显著;(3)片筏基础、桩基础和桩筏基础结构的加速度响应接近,而独立基础结构的加速度与前三者差异明显,但随着楼层的增大,基础形式对结构层间位移角的影响逐渐减弱;(4)上、下盘结构的峰值加速度、峰值位移大小及峰值出现的时间等存在一定差异,这是由于地震波经过地裂缝时发生复杂的反射和折射,结构受到非一致性激励造成的。     

Active phase of a substorm as a chain of two types of reconnection: In the closed plasma sheet and in the open tail lobes

The maps of the field-aligned current (FAC) density distribution in the ionosphere obtained by the TIM-2 magnetogram inversion technique are used to investigate the August 27, 2001 substorm. The open magnetic flux Ψ and intensity J of the substorm current wedge (SCW) have been determined with a step of 1–5 min. The substorm onsets are divided into two types, PSR (plasma sheet reconnection) and TLR (tail lobe reconnection). The fast expansion tailward of the PSR region is described as the transition from PSR to PSR+TLR. Assuming that the SCW FACs flow down into the ionosphere from the edges of the disruption region of the cross-tail dawn-dusk current, several parameters of the disruption region have been estimated. The disrupted magnetic field has been found to be ∼5% of the undisrupted one for PSR and ∼95% for PSR+TLR. The disturbance power Q for PSR is an order of magnitude lower than that for PSR+TLR. The abrupt growth of Q during the transition from PSR to PSR+TLR is observed over the entire SCW area from its near-Earth part to the midtail and distant tail.     

Simulation of Lake-Groundwater Interaction under Steady-State Flow

MODFLOW is one of the most popular groundwater simulation tools available; however, the development of lake modules that can be coupled with MODFLOW is lacking apart from the LAK3 package. This study proposes a new approach for simulating lake - groundwater interaction under steady-state flow, referred to as the sloping lakebed method (SLM). In this new approach, discretization of the lakebed in the vertical direction is independent of the spatial discretization of the aquifer system, which can potentially solve the problem that the lake and groundwater are usually simulated at different scales. The lakebed is generalized by a slant at the bottom of each lake grid cell, which can be classified as fully submerged, dry, and partly submerged. The SLM method accounts for all lake sources and sinks, establishing a governing equation that can be solved using Newton's method. A benchmarking case study was conducted using a modified model setup in the LAK3 user manual. It was found that when there is a sufficient number of layers at the top of the groundwater model, SLM simulates an almost identical groundwater head as the LAK3-based model; when the number of layers decreases, SLM is unaffected while LAK3 may be at a risk of giving unrealistic results. Additionally, the SLM can reflect the relationship between the simulated lake surface area and lake water depth more accurately. Therefore, the SLM method is a promising alternative to the LAK3 package when simulating lake - groundwater interaction.     

Potential ecological risk of cadmium, lead and arsenic in agricultural black soil in Jilin Province, China

Potential ecological risk of cadmium (Cd), lead (Pb) and arsenic (As) in agricultural black soil in Jilin Province, China was analyzed by the methods of risk assessment based on dose–effect relationships and ecological risk index. Heavy Cd-contamination occurred mainly around the coal mine region. The accumulation area for Pb appeared mostly in the suburbs and roadsides, whereas the higher As content was mainly found in the farmland of suburb and coal mine vicinity. In acute toxicity test, Cd, Pb and As in the soil had adverse effects on both roots and shoots growth in soybean with the greatest toxicity of arsenic and the least toxicity of lead at the same concentration levels. Exposed to Cd, Pb and As, the EC₅₀ (50% effective concentration) values for the growth of soybean root (shoot) were 212.59 (376.70), 528.53 (828.69) and 194.60 (299.03) mg/kg, respectively. Results of potential ecological risk index showed that soil contamination from Cd in some samples had very high potential ecological risk; Pb contamination for almost all sampling sites had moderate ecological risk; while soil contamination from As had low ecological risk. With the present accumulation rate, concentrations of Cd, Pb and As in agricultural black soil near coal mine would reach the threshold values in 68, 175 and 120 years, respectively.     

Introduction of structural aseismic research in China in recent four years

Introduction Greeting the coming of the 21st century, Professor HU Yu-xian and other Chinese scholars briefed the trend of earthquake engineering in China and aboard (HU, 1999; HU, ZHOU, 1999). The experiences and lessons learning from the destructive earthquakes in China and abroad in re-cent years, the damage action of the large velocity impulse in ground motion in near field in seis-mic design, numerous earthquake examples show that there are many weaknesses in aspects of earthquake p…     

800KaB．P．来西藏“一江两河”中游地区的气候与西南季风变化

西藏“一江两河”中游地区风成地层沉积时代、沉积相和磁化率等研究结果表明，早在８００ＫａＢ．Ｐ．前西南季风就已存在，受全球气候波动和青藏高原隆起的影响，其盛行衰变与东南季风具有较好的一致性，主要表现为本区地层所记录的气候变化信息不如东南季风区详细；而且西南季风因高原屏障作用给本区带来的降水愈来愈少，气候明显地向干冷化发展。     

发展互花米草开发华南热带海滩

互花米草是禾本科多年生高秆型草本植物，原产北美洲大西洋海岸，７０年代末引入我国，本文在大量试验基础上，对互花米草在华南热带海滩的生长适应性，生物量和收获量及其在促淤造陆，改良土壤等方面作了论述，并对互花米草的抗污染作用和作为饲料，饵料等的经济作用也进行了定量分析，认为互花米草在华南热带海滩具有广阔的开发应用前景。     

Tropospheric Wet Refractivity Tomography Based on the BeiDou Satellite System简

This paper presents a novel approach for assessing the precision of the wet refractivity field using BDS （BeiDou navigation satellite system） simulations only,GPS,and BDS＋GPS for the Shenzhen and Hongkong GNSS network.The simulations are carried out by adding artificial noise to a real observation dataset.Instead of using the δ and σ parameters computed from slant wet delay,as in previous studies,we employ the Bias and RMS parameters,computed from the tomography results of total voxels,in order to obtain a more direct and comprehensive evaluation of the precision of the refractivity field determination.The results show that：（1） the precision of tropospheric wet refractivity estimated using BDS alone （only 9 satellites used） is basically comparable to that of GPS; （2） BDS＋GPS （as of current operation） may not be able to significantly improve the data＇s spatial density for the application of refractivity tomography; and （3） any slight increase in the precision of refractivity tomography,particularly in the lower atmosphere,bears great significance for any applications dependent on the Chinese operational meteorological service.