Understanding Molecular Dynamics with Stochastic Processes via Real or Virtual Dynamics

Molecular dynamics with the stochastic process provides a convenient way to compute structural and thermodynamic properties of chemical, biological, and materials systems. It is demonstrated that the virtual dynamics case that we proposed for the Langevin equation [J. Chem. Phys. 147, 184104 （2017）] in principle exists in other types of stochastic thermostats as well. The recommended ＂middle＂ scheme [J. Chem. Phys. 147, 034109 （2017）] of the Andersen thermostat is investigated as an example. As shown by both analytic and numerical results, while the real and virtual dynamics cases approach the same plateau of the characteristic correlation time in the high collision frequency limit, the accuracy and efficiency of sampling are relatively insensitive to the value of the collision frequency in a broad range. After we compare the behaviors of the Andersen thermostat to those of Langevin dynamics, a heuristic schematic representation thermostatting processes with molecular is proposed for understanding efficient stochastic dynamics.

Inverse Dynamics of Delta Robot Based on the Principle of Virtual Work

A systematic methodology for solving the inverse dynamics of the Delta robot is presented.First,the inverse kinematics is solved based on the vector method.A new form of the Jacobi matrix formulized by the vectors is obtained so the three types kinematics singularities namely inverse, direct and combined types, can be identified with the physical meaning.Then based on the principle of virtual work, a methodology for driving the dynamical equations of motion is developed.Meanwhile the whole actuating torques, the torques caused by the gravity, the velocity and the acceleration are computed respectively in the numerical example. Results show that torque caused by the acceleration term is much bigger than the other two terms.This approach leads to efficient algorithms since the constraint forces and moments of the robot system have been eliminated from the equations of motion and there is no differential equation for the whole procedure when the principle of virtual work is applied to solving the inverse dynamical problem.

Influence of static cartoons combined with dynamic virtual environments on preoperative anxiety of preschool-aged children undergoing surgery

BACKGROUND Preschoolers become anxious when they are about to undergo anesthesia and surgery,warranting the development of more appropriate and effective interventions.AIM To explore the effect of static cartoons combined with dynamic virtual environments on preoperative anxiety and anesthesia induction compliance in preschool-aged children undergoing surgery.METHODS One hundred and sixteen preschool-aged children were selected and assigned to the drug(n=37),intervention(n=40),and control(n=39)groups.All the children received routine preoperative checkups and nursing before being transferred to the preoperative preparation room on the day of the operation.The drug group received 0.5 mg/kg midazolam and the intervention group treatment consisting of static cartoons combined with dynamic virtual environments.The control group received no intervention.The modified Yale Preoperative Anxiety Scale was used to evaluate the children’s anxiety level on the day before surgery(T0),before leaving the preoperative preparation room(T1),when entering the operating room(T2),and at anesthesia induction(T3).Compliance during anesthesia induction(T3)was evaluated using the Induction Compliance Checklist(ICC).Changes in mean arterial pressure(MAP),heart rate(HR),and respiratory rate(RR)were also recorded at each time point.RESULTS The anxiety scores of the three groups increased variously at T1 and T2.At T3,both the drug and intervention groups had similar anxiety scores,both of which were lower than those in the control group.At T1 and T2,MAP,HR,and RR of the three groups increased.The drug and control groups had significantly higher MAP and RR than the intervention group at T2.At T3,the MAP,HR,and RR of the drug group decreased and were significantly lower than those in the control group but were comparable to those in the intervention group.Both the drug and intervention groups had similar ICC scores and duration of anesthesia induction(T3),both of which were higher than those of the control group.CONCLUSION Combining static cartoons with dynamic virtual environments as effective as medication,specifically midazolam,in reducing preoperative anxiety and fear in preschool-aged children.This approach also improve their compliance during anesthesia induction and helped maintain their stable vital signs.

Multiway Dynamic Trust Chain Model on Virtual Machine for Cloud Computing

This paper sums up four security factors after analyzing co-residency threats caused by the special multitenant environment in the cloud.To secure the factors,a multiway dynamic trust chain transfer model was proposed on the basis of a measurement interactive virtual machine and current behavior to protect the integrity of the system.A trust chain construction module is designed in a virtual machine monitor.Through dynamic monitoring,it achieves the purpose of transferring integrity between virtual machine.A cloud system with a trust authentication function is implemented on the basis of the model,and its practicability is shown.

Recent Progress of Marine Geographic Information System in China:A Review for 2006-2010

In this article,the progress of marine geographic information system(MGIS) in China during 2006?2010 is reviewed with emphases on generic MGIS,advanced MGIS and MGIS-based applications.Generic MGIS can be divided into two categories:data-oriented MGIS and user-oriented MGIS,recent achievements of which by Chinese researchers are summarized respectively.Advanced MGIS mainly involves the establishment of 3D virtual marine environment and 'Digital Ocean'.An overview of the 3D MGIS based simulations in the context of ocean phenomena,ocean engineering and ocean battlefield is also presented.Several sug-gestions for future development of MGIS in China are proposed,and trends of development are addressed.

A Multi-Agent Expert System for Prevention of Child Abuse and Neglect

When a child abuse situation arises, the responsible agencies and entities in charge of response should be capable of providing a fast and personalized solution for the good of the child. This need leads the authors to consider the formation of dynamic virtual organizations tailored to each particular abuse case. In the authors＇ approach the partner selection of these collaborative networks is done through a software tool that combines two technologies from the field of artificial intelligence, specifically multi-agent systems and expert systems. In addition, these partners come from the breeding environment constituted by all the agencies or individuals, either in a region or locality, which have the potential of response.

3D COMPUTER SIMULATION FOR LIGNIFICATION OF ANCIENT CHINESE TIMBER BUILDINGS

A pioneer research work was carried out by investigators engaged in surveying and mapping for describing ancient Chinese timber buildings by 3D frame graphs with a computer.Users can know the structural layers and the assembly process of these buildings if the frame graphs are processed further with a computer model.This can be implemented by computer simulation technique.This technique display the raw data on the screen of a computer and interactively manage them by combining technologies from computer graphics and image processing,multi-media technology,artificial intelligence,highly parallel real-time computation technique and human behavior science.This paper presents the implementing procedure of lignification simulation for large-sized wooden buildings as well as 3D dynamic assembly of these buildings under the 3DS MAX environment.The results from computer simulation are also shown in the paper.

Exact Computation of Parallel Robot's Generalized Inertia Matrix

According to the definition of the new hypothetical states which have obvious physical significance and are termed as no-gravity static and accelerated states, a method for exact computation of the parallel robot＇s generalized inertia matrix is presented. Based on the matrix theory, the generalized inertia matrix of the parallel robot can be computed on the assumption that the robot is in these new hypothetical states respectively. The approach is demonstrated by the Delta robot as an example. Based on the principle of the virtual work, the inverse dynamics model of the robot is formulized after the kinematics analysis. Finally, a numerical example is given and the element distribution of the Delta robot＇s inertia matrix in the workspace is studied. The method has computationa＇, advantage of numerical accuracy for the Delta robot and can be parallelized easily.

Relationship between the Virtual Dynamic Thinning Line and the Self-Thinning Boundary Line in Simulated Plant Populations

The self-thinning rule defines a straight upper boundary line on log-log scales for all possible combinations of mean individual biomass and density in plant populations. Recently, the traditional slope of the upper boundary line, -3/2, has been challenged by -4/3 which is deduced from some new mechanical theories, like the metabolic theory. More experimental or field studies should be carried out to identify the more accurate self-thinning exponent. But it＇s hard to obtain the accurate self-thinning exponent by fitting to data points directly because of the intrinsic problem of subjectivity in data selection. The virtual dynamic thinning line is derived from the competition-density （C-D） effect as the initial density tends to be positive infinity, avoiding the data selection process. The purpose of this study was to study the relationship between the virtual dynamic thinning line and the upper boundary line in simulated plant stands. Our research showed that the upper boundary line and the virtual dynamic thinning line were both straight lines on log-log scales. The slopes were almost the same value with only a very little difference of 0.059, and the intercept of the upper boundary line was a little larger than that of the virtual dynamic thinning line. As initial size and spatial distribution patterns became more uniform, the virtual dynamic thinning line was more similar to the upper boundary line. This implies that, given appropriate parameters, the virtual dynamic thinning line may be used as the upper boundary line in simulated plant stands.

I-Neat:An Intelligent Framework for Adaptive Virtual Machine Consolidation

With the increasing use of cloud computing,high energy consumption has become one of the major challenges in cloud data centers.Virtual Machine(VM)consolidation has been proven to be an efficient way to optimize energy consumption in data centers,and many research works have proposed to optimize VM consolidation.However,the performance of different algorithms is related with the characteristics of the workload and system status;some algorithms are suitable for Central Processing Unit(CPU)-intensive workload and some for web application workload.Therefore,an adaptive VM consolidation framework is necessary to fully explore the potential of these algorithms.Neat is an open-source dynamic VM consolidation framework,which is well integrated into OpenStack.However,it cannot conduct dynamic algorithm scheduling,and VM consolidation algorithms in Neat are few and basic,which results in low performance for energy saving and Service-Level Agreement(SLA)avoidance.In this paper,an Intelligent Neat framework(I-Neat)is proposed,which adds an intelligent scheduler using reinforcement learning and a framework manager to improve the usability of the system.The scheduler can select appropriate algorithms for the local manager from an algorithm library with many load detection algorithms.The algorithm library is designed based on a template,and in addition to the algorithms of Neat,I-Neat adds six new algorithms to the algorithm library.Furthermore,the framework manager helps users add self-defined algorithms to I-Neat without modifying the source code.Our experimental results indicate that the intelligent scheduler and these novel algorithms can effectively reduce energy consumption with SLA assurance.

Individual knowledge sharing behavior in dynamic virtual communities： the perspectives of network effects and status competition

Purpose： While most literature concerning knowledge sharing examines it as an organizational method for innovation and value creation, this paper considers online knowledge sharing as an individual behavior decision embedded in a virtual community. We attempt to explore which sharing behavior can help individual participants gain a better position in an online community, improving social status, reputation, and other social networking interests. Design/methodology/approach： We collected and measured the knowledge sharing activities and discussion from a Chinese online expertise knowledge network in Business Management Consulting. We tested the mediating effects of the sharing behavior of the major members of the online knowledge network on members＇ status （network centrality） in different time units （days）. Findings： In a dynamic virtual community, the direct result of knowledge sharing behavior is reflected in the individual status position （the degree of node centrality）. At the same time, individual knowledge sharing behavior has an ＂inertia effect＂： individual prior status （the degree of node centrality） affects current knowledge sharing behavior, while current knowledge sharing behavior affects current status in the knowledge network, forming an inertial circuit between personal behavior and network status. Originality/value： We expound the theory of individual knowledge sharing in the context of an inter-person dynamic virtual community; we provide action ＂strategies＂ for individual knowledge shating behavior choice, for better understanding the nature of individual knowledge behavior, and we also propose and test the ＂inertia effect＂ of knowledge sharing behavior and the knowledge network, and demonstrate the theory of network effects from an individual perspective.

Mercury: Combining Performance with Dependability Using Self-Virtualization

Virtualization has recently gained popularity largely due to its promise in increasing utilization, improving availability and enhancing security. Very often, the role of computer systems needs to change as the business environment changes. Initially, the system may only need to host one operating system and seek full execution speed. Later, it may be required to add other functionalities such as allowing easy software/hardware maintenance, surviving system failures and hosting multiple operating systems. Virtualization allows these functionalities to be supported easily and effectively. However, virtualization techniques generally incur non-negligible performance penalty. Fortunately, many virtualization- enabled features such as online software/hardware maintenance and fault tolerance do not require virtualization standby all the time. Based on this observation, this paper proposes a technique, called Self-virtualization, which provides the operating system with the capability to turn on and off virtualization on demand, without disturbing running applications. This technique enables computer systems to reap most benefits from virtualization without sacrificing performance. This paper presents the design and implementation of Mercury, a working prototype based on Linux and Xen virtual machine monitor. The performance measurement shows that Mercury incurs very little overhead： about 0.2 ms on 3 GHz Xeon CPU to complete a mode switch, and negligible performance degradation compared to Linux.

Route Guardian: Constructing Secure Routing Paths in Software-Defined Networking

Software-Defined Networking（SDN） decouples the control plane and the data plane in network switches and routers, which enables the rapid innovation and optimization of routing and switching configurations. However,traditional routing mechanisms in SDN, based on the Dijkstra shortest path, do not take the capacity of nodes into account, which may lead to network congestion. Moreover, security resource utilization in SDN is inefficient and is not addressed by existing routing algorithms. In this paper, we propose Route Guardian, a reliable securityoriented SDN routing mechanism, which considers the capabilities of SDN switch nodes combined with a Network Security Virtualization framework. Our scheme employs the distributed network security devices effectively to ensure analysis of abnormal traffic and malicious node isolation. Furthermore, Route Guardian supports dynamic routing reconfiguration according to the latest network status. We prototyped Route Guardian and conducted theoretical analysis and performance evaluation. Our results demonstrate that this approach can effectively use the existing security devices and mechanisms in SDN.