运用代数法的事件驱动分子动力学模拟

分子动力学模拟是随着计算机技术发展而兴起的一种科学计算方法,在基于事件驱动的椭球分子动力学模拟中碰撞检测是一个核心计算问题。为提高基于事件驱动的分子动力学模拟的效率,提出利用代数法计算椭球分子间的碰撞时间,通过椭球分子膨胀形成包围域,并使用代数法建立最近邻居列表。模拟实验结果表明,该算法的计算效率明显提高,特别是该算法不受椭球粒子长宽比的影响。

中国南海高分辨率大地水准面及海底地形特征

利用高分辨率的海洋卫星测高资料,构制中国南海及邻近海域完整到3600阶次的甚高阶大地水准面数值模型,使其表示大地水准面起伏的空间分辨率好于5.5km;对大地水准面进行滤波和平滑,滤除相关的波长,得到了中国南海及邻近海域高分辨率的海底地形图像,清晰地勾画出中国南海及邻近海域海底地貌、构造特征及动力学事件,可作为海洋测深预报和构造的重新构成等之参考。

亚暴期间场向电流的特征

分析了由ISEE 1和ISEE 2飞船在亚暴期间观测到的场向电流的特性 ,包括场向电流所伴随的行星际磁场、地方时与L值分布以及场向电流强度和密度随亚暴位相的变化 ,并着重分析了亚暴电流楔的特征。结果表明 ,亚暴膨胀相的场向电流强度和密度都达到极大值 ;亚暴的膨胀相是由行星际磁场转向或南向分量变小触发的 。

胸液含量预测危重患儿持续性肾脏替代治疗中容量状态的预后研究

背景胸液含量(TFC)是电子心力监测法(EC)以胸腔基础阻抗标准化导出的一项容量指标,反映血管内、血管外及胸腔组织间隙总液体含量,国内外有关危重患儿持续性肾脏替代治疗(CRRT)期间使用TFC评估容量状态的临床研究极少。目的TFC能否成为CRRT期间容量状态的评估指标,并指导CRRT期间的液体管理。设计预后研究。方法纳入PICU中行CRRT≥24 h的危重患儿,CRRT以颈内静脉、股静脉或锁骨下静脉双腔管为血管通路。采集基线、实验室、EC测量和临床液体状态指标,以发生血流动力学不良事件[低血压或心律失常,需行扩容治疗,正性肌力药物评分(IS)最大值(ISmax)>IS]为结局指标,评估CRRT不同时点(开始时、24 h和结束时)容量指标[每搏输出变异(SVV)、TFC和B型钠尿肽(BNP)]与超滤量间的相关性,并评估容量指标是否可以预测结局事件的发生。主要结局指标血流动力学不良事件预测指标。结果①43例59例次CRRT数据进入本文分析。与CRRT开始相比,CRRT 24 h时TFC、Hct、Hb差异有统计学意义(P均<0.05);CRRT结束时与CRRT开始时相比,SVV、TFC、心肌收缩指数(ICON)、BNP、Hct、Scr、BUN、Hb、ALB差异均有统计学意义(P<0.05)。②液体超负荷(FO)与TFC(始)、SVV(始)正相关;超滤量/体重与TFC(始)正相关,与ΔTFC(24 h)、ΔTFC(末)、TFCd0%(24 h)、TFCd0%(末)负相关;超滤速率与SVV(始)、TFC(始)、BNP(始)正相关,与ΔTFC(24 h)、ΔTFC(末)、TFCd0%(24 h)负相关;平衡量/体重与ΔTFC(24 h)、ΔTFC(末)、TFCd0%(24 h)、TFCd0%(末)、ΔBNP(末)正相关,与BNP(始)负相关。CRRT期间33例次发生了血流动力学不良事件,单因素分析显示,BNP(始)、ΔBNP(末)、超滤速率、TFCd0%(24 h)差异有统计学意义;多因素分析显示,TFCd0%(24 h)≤-3.64 kΩ^(-1)(OR=8.84,95%CI:1.16~67.44,P=0.036)和ΔBNP(末)≤-133.8 pg·mL^(-1)(OR=5.67,95%CI:1.24~26.03,P=0.007)更易发生血流动力学紊乱。结论TFC用于监测危重患儿CRRT治疗中的液体状态可行,特别是CRRT开始后24 h时TFCd0%≤-3.64 kΩ^(-1)需警惕发生血流动力学不良事件。

A GIS-based Earthquake and Tsunami Emergency Command System for Seaside Cities

In this paper the geographical information system （GIS） is applied to earthquake and tsunami emergency work and an earthquake and tsunami emergency command system （ETECS） for seaside cities is developed which is composed of a basic database and six subsystems. By employing this system, the responsible municipal departments can make rapid prediction before the occurrence of earthquake or tsunami, make commanding decisions concerning the disaster-fight during the disastrous event, and make rapid estimates of the casualties and economic losses. So that the government could conduct relief work in time and planning for future disaster reduction and prevention.

A Study of Soil-dynamics Based on a Simulated Drought in an Alpine Meadow on the Tibetan Plateau

Extreme weather events have played an important role in driving the ecosystem dynamics in high altitude areas, but the underlying mechanism remains unclear. To understand if and how the soil processes of an ecosystem react to extreme drought, we manipulated a once-in-a-century meteorological extreme drought in an alpine meadow on the Tibetan Plateau, which is also known as the ＂forerunner of global weather changes＂. The extremity was determined by statistical extreme weather events with respect to a historical reference period from April to September during 1962 - 2004, where the local historical precipitation data was calculated and intensified to loo-year recurrent drought event with Gumbel I distribution. The indicators we measured included soil microbial biomass C/N/P and soil enzymatic activities of phosphatase （AP） disbounding organic phosphate, cellobiohydrolase （CBH）, β- glucocidase （BG）, N-releasing enzyme N-acetyl- glucosaminidase （NAG） as well as soil respirations, during and after the treatments. It was found that the manipulated event induced a rapid shift in microbial biomass and activities, indicating a lower resistance of the underground process. However, the microbial and biochemical parameters saw rapid recovery after the event, which meant the soil processes enjoyed high resilience. The high responsiveness and lag-time effects of the soil indicators rendered new horizons for us to evaluate the interaction between the extremes and the ecosystem stability. Our study indicated that the once-in-a-century extreme drought induced very short term response in the soil biotic process, and the soil processes worked to buffer against such events under the observation period.

Hydrodynamic parameters in a flood impacted boulder block ramp： Krzczonówka mountain stream, Polish Carpathians

Boulder block ramps are river engineering structures used to stabilise river beds. Block ramps provide a semi-natural and aesthetically pleasing solution to certain river engineering problems in mountain streams. When constructing block ramps,one can use the dissipative behaviour of large macroroughness elements randomly placed on the river bed to enhance fish migration in an upstream direction thus, in this sense, meeting the requirements of the EU Water Framework Directive. Block ramps are often designed and constructed to replace damaged drop hydraulic structures in the channels of mountain streams. This paper investigates the resilience of a particular block ramp placed in the Krzczonówka stream(Polish Carpathians) in terms of the engineering design function and its durability against damaging. A hydrodynamic analysis of a block ramp is presented before and after a flood event that changed the configuration of the blocks. The seminatural unstructured hydraulic structure was built on the Krzczonowka stream to protect gas pipes which are located beneath it. As a result of several floods, the boulder block chute described in this paper was damaged, and some boulders were dislodged and transported downstream. Our post-flood investigations of bathymetry and velocity revealed that even damaged boulder blocks, removed from the chute and displaced downstream of the structure, still provide significant energy dissipation of the flowing water. The novel of our paper is for the first time showing very detailed analysis of unstructured block ramp hydrodynamics parameters done in the field.Also the novel finding of our investigations shows that before and after the flood event the unstructured block ramp structure, is still fish friendly in terms of hydrodynamics.

Integrating Factors and Conservation Laws of Generalized Birkhoff System Dynamics in Event Space

In this paper, the conservation laws of generalized Birkhoff system in event space are studied by using the method of integrating factors. Firstly, the generalized Pfaff-Birkhoff principle and the generalized Birkhoff equations are established, and the definition of the integrating factors for the system is given. Secondly, based on the concept of integrating factors, the conservation theorems and their inverse for the generalized Birkhoff system in the event space are presented in detail, and the relation between the conservation laws and the integrating factors of the system is obtained and the generalized Killing equations for the determination of the integrating factors are given. Finally, an example is given to illustrate the application of the results.

A Possible Interpretation of Burst-Like Characteristics of Explosive Events

Explosive events have been observed to occur consecutively in bursts at intermittent locations along theboundary near the opposite polarity. The aim of the present paper is to explore a possible mechanism to interpret thisburst-like characteristic of explosive events. The 2D magnetohydrodynamic (MHD) numerical simulations with resistivityhave been carried out to reproduce the intermittent spatial-temporal magnetic reconnection events taking place along thelong, compressible current sheet. The observed density enhancements in previously published results have been verifiedto be associated to magnetic reconnection sites. Late observational evidences, which support present attempts, have alsobeen found, at least in morphological evolution of the consecutive explosive events.

Event-driven Dynamic and Intelligent Scheduling for Agile Manufacturing Based on Immune Mechanism and Expert System

Based on the biological immune concept, immune response mechanism and expert system, a dynamic and intelligent scheduling model toward the disturbance of the production such as machine fault,task insert and cancel etc. Is proposed. The antibody generation method based on the sequence constraints and the coding rule of antibody for the machining procedure is also presented. Using the heuristic antibody generation method based on the physiology immune mechanism, the validity of the scheduling optimization is improved, and based on the immune and expert system under the event-driven constraints, not only Job-shop scheduling problem with multi-objective can be solved, but also the disturbance of the production be handled rapidly. A case of the job-shop scheduling is studied and dynamic optimal solutions with multi-objective function for agile manufacturing are obtained in this paper. And the event-driven dynamic rescheduling result is compared with right-shift rescheduling and total rescheduling.

Evolved Urban Form to Respond to Extreme Sea Level Events in Coastal Cities

Along with climate change and global warming, ESLEs （extreme sea level events） are seriously threatening coastal cities＇ development. In order to respond to such events, transformational adaptation strategy in urban planning might play an important role. For instance, it has been proposed that BCR （building coverage ratio） should be minimized to a certain range in order to enhance coastal areas＇ resiliency. For the purpose of urban planning practices, the main objective of this research is to develop a method which could formulate the proper BCR range in vulnerable coastal areas. The research is conducted through simulating storm surge floods in simplified waterfront settlements with different BCRs. Data representing the impact of ESLEs collected through CFD （computational fluid dynamic） simulations has been examined. This research has proved that in dense coastal areas, ESLEs may cause serious damage to the built environment if their protective structures fail. It showed that controlling BCR is an effective way to enhance their resiliency. When the BCR is low, the pressure caused by storm surge floods and wave height can be greatly reduced. However, decreased BCR may also reduce land utilization efficiency. Simulation results indicated that controlling the BCR to around 36% might be the most effective scenario which balances resiliency and land use efficiency. They also showed that under the same storm surge flood scenario, the pressures caused by flood waves could be reduced if the length of the building is increased. This study might be considered as transformational adaptation measures that contributes some knowledge for waterfront development in vulnerable locations, and it also provides scientific and useful proof for sustainable strategies in coastal cities and reveals that particular urban design tools, such as BCR control, could play an essential role in responding to ESLEs.

Maritime network dynamics before and after international events

Investigating the influence of international events on global maritime networks is a challenging task that must comprehensively incorporate geographical, political, and maritime sciences. Understanding global maritime network dynamics is an initial and critical step in this investigation. This study proposes an automatic identification system(AIS)-based approach to understanding maritime network dynamics before and after international events. In this approach, a spatiotemporal modeling method is introduced to measure the similarity in shipping trends before and after international events. Then, a spatiotemporal analytic framework is proposed to understand the maritime network dynamics by grouping similar situation, and assessing possible indirect effects within a network. Finally, three case studies of international events, military conflict, lifted economic sanctions, and government elections, were used to investigate the observed network dynamics possibly affected by international events. The results indicate that container, tanker, and bulk shipping between India and its connected countries all declined more than 69% after military conflicts between India and Pakistan in August 2015. Tanker shipping between Iran and the United Arab Emirates increased 51% after economic sanctions on Iran were lifted. Container shipping between Sri Lanka and Singapore, Malaysia, and India increased more than 74% after the general election in Sri Lanka. These investigations demonstrate the feasibility of the proposed approach in assessing the possible effects of international events on maritime network dynamics.

Adaptive Event-Based Consensus of Multi-Agent Systems with General Linear Dynamics

In this paper, adaptive event-based consensus of multi-agent systems with general linear dynamics is considered. A novel adaptive event-based controller and a state-dependent triggering function are proposed for each agent. The consensus can be achieved without the assumption that（A, B） is stabilizable. Furthermore, the Zeno-behavior of the concerned closed-loop system is also excluded under certain conditions. Finally, a numerical simulation example is presented to show the effectiveness of the theoretical results.

Genesis of the 2014–2016 El Nio events

The 2015/2016 El Nio was one of the strongest El Nio events in history, and this strong event was preceded by a weak El Nio in 2014. This study systematically analyzed the dynamical processes responsible for the genesis of these events. It was found that the weak 2014 El Nio had two warming phases, the spring-summer warming was produced by zonal advection and downwelling Kelvin waves driven by westerly wind bursts(WWBs), and the autumn-winter warming was produced by meridional advection, surface heating as well as downwelling Kelvin waves. The 2015/2016 extreme El Nio, on the other hand, was primarily a result of sustained zonal advection and downwelling Kelvin waves driven by a series of WWBs, with enhancement from the Bjerknes positive feedback. The vast difference between these two El Nio events mainly came from the different amount of WWBs in 2014 and 2015. As compared to the 1982/1983 and 1997/1998 extreme El Nio events, the 2015/2016 El Nio exhibited some distinctive characteristics in its genesis and spatial pattern. We need to include the effects of WWBs to the theoretical framework of El Nio to explain these characteristics, and to improve our understanding and prediction of El Nio.

Suppression dampens unpleasant emotion faster than reappraisal:Neural dynamics in a Chinese sample

The timing dynamics of regulating negative emotion with expressive suppression and cognitive reappraisal were investigated in a Chinese sample. Event-Related Potentials were recorded while subjects were required to view, suppress emotion expression to, or reappraise emotional pictures. The results showed a similar reduction in self-reported negative emotion during both strategies. Additionally, expressive suppression elicited larger amplitudes than reappraisal in central-frontal P3 component(340–480 ms). More importantly, the Late Positive Potential(LPP) amplitudes were decreased in each 200 ms of the 800–1600 ms time intervals during suppression vs. viewing conditions. In contrast, LPP amplitudes were similar for reappraisal and viewing conditions in all the time windows, except for the decreased amplitudes during reappraisal in the 1400–1600 ms. The LPP(but not P3) amplitudes were positively related to negative mood ratings, whereas the amplitudes of P3, rather than LPP, predict self-reported expressive suppression. These results suggest that expressive suppression decreases emotion responding more rapidly than reappraisal, at the cost of greater cognitive resource involvements in Chinese individuals.