可控阵的k-泛传递刻画

研究 k-泛传递的性质及其图的特征 ,证明 acyclicity阵是可控阵 ,实现对可控阵的传递性刻画 。

一类具有时间依赖的病毒动力学模型

研究了一类具有时间依赖的病毒动力学模型.在引入基本再生率R0的基础上,运用持久性理论,证明了当R0>1时,系统至少存在一个正周期解且病毒持续;当R0<1时,病毒清除.

一种基于模糊聚类的网格DAG任务图调度算法

针对网格环境中,任务调度的目标系统具有规模庞大、分布异构和动态性等特点,提出一种基于模糊聚类的网格异构任务调度算法.以往的很多调度算法需要在调度的每一步遍历整个目标系统,虽然能够获得较小的makespan,但是无疑增加了整个调度的Runtime.定义了一组刻画处理单元综合性能的特征,利用模糊聚类方法对目标系统(处理单元网络)进行预处理,实现了对处理单元网络的合理划分,使得在任务调度时能够较准确地优先选择综合性能较好的处理单元聚类,从而缩小搜索空间,大量减少任务调度时选择处理单元的时间耗费.此外,就绪任务优先级的构造既隐含考虑了关键路径上节点的执行情况对整个程序执行的影响,又考虑了异构资源对任务执行的影响.实验及性能分析比较的结果表明,定义的处理器特征能够实现对处理器网络的合理划分,而且随着目标系统规模的增大,所提出的算法优越性越来越明显.

Generating Compatibility Conditions and General Relativity

The search for the generating compatibility conditions (CC) of a given operator is a very recent problem met in general relativity in order to study the Killing operator for various standard useful metrics. Accordingly, this paper can be considered as a natural continuation of a previous paper recently published in JMP under the title Minkowski, Schwarschild and Kerr metrics revisited. In particular, we prove that the intrinsic link existing between the lack of formal exactness of an operator sequence on the jet level, the lack of formal exactness of its corresponding symbol sequence and the lack of formal integrability (FI) of the initial operator is of a purely homological nature as it is based on the long exact connecting sequence provided by the so-called snake lemma in homological algebra. It is therefore quite difficult to grasp it in general and even more difficult to use it on explicit examples. It does not seem that any one of the results presented in this paper is known as most of the other authors who studied the above problem of computing the total number of generating CC are confusing this number with the degree of generality introduced by A. Einstein in his 1930 letters to E. Cartan. One of the motivating examples that we provide is so striking that it is even difficult to imagine that such an example could exist. We hope this paper could be used as a source of testing examples for future applications of computer algebra in general relativity and, more generally, in mathematical physics.

Multi-satellite observation integrated scheduling method oriented to emergency tasks and common tasks

Satellite observation scheduling plays a significant role in improving the efficiency of satellite observation systems.Although many scheduling algorithms have been proposed,emergency tasks,characterized as importance and urgency（e.g.,observation tasks orienting to the earthquake area and military conflict area）,have not been taken into account yet.Therefore,it is crucial to investigate the satellite integrated scheduling methods,which focus on meeting the requirements of emergency tasks while maximizing the profit of common tasks.Firstly,a pretreatment approach is proposed,which eliminates conflicts among emergency tasks and allocates all tasks with a potential time-window to related orbits of satellites.Secondly,a mathematical model and an acyclic directed graph model are constructed.Thirdly,a hybrid ant colony optimization method mixed with iteration local search（ACO-ILS） is established to solve the problem.Moreover,to guarantee all solutions satisfying the emergency task requirement constraints,a constraint repair method is presented.Extensive experimental simulations show that the proposed integrated scheduling method is superior to two-phased scheduling methods,the performance of ACO-ILS is greatly improved in both evolution speed and solution quality by iteration local search,and ACO-ILS outperforms both genetic algorithm and simulated annealing algorithm.

Performance analysis and comparison of PoW,PoS and DAG based blockchains

In the blockchain,the consensus mechanism plays a key role in maintaining the security and legitimation of contents recorded in the blocks.Various blockchain consensus mechanisms have been proposed.However,there is no technical analysis and comparison as a guideline to determine which type of consensus mechanism should be adopted in a specific scenario/application.To this end,this work investigates three mainstream consensus mechanisms in the blockchain,namely,Proof of Work(PoW),Proof of Stake(PoS),and Direct Acyclic Graph(DAG),and identifies their performances in terms of the average time to generate a new block,the confirmation delay,the Transaction Per Second(TPS)and the confirmation failure probability.The results show that the consensus process is affected by both network resource(computation power/coin age,buffer size)and network load conditions.In addition,it shows that PoW and PoS are more sensitive to the change of network resource while DAG is more sensitive to network load conditions.

A new acyclic peroxide from Aspergillus nidulans SD-531,a fungus obtained from deep-sea sediment of cold spring in the South China Sea

A new acyclic peroxide derivative asperoxide A(1),along with 13 known compounds,namely,microperfuranone(2),9-hydroxymicroperfuranone(3),gibellulin A(4),lecanoric acid(5),terrequinone A(6),sterigmatocystin(7),isosecosterigmatocystin(8),arugosin C(9),curvularin(10),3,3'-diindolylmethane(11),austinol(12),austin(13),and dehydroaustin(14),were isolated and identified from the culture extract of Aspergillus nidulans SD-531,a fungus obtained from the deep-sea sediment of cold spring in the South China Sea.Their structures were determined based on detailed interpretation of nuclear magnetic resonance(NMR)spectroscopic and mass spectrometry data analysis.All the isolated compounds were evaluated for antimicrobial activities against human and aquatic bacteria as well as plant pathogenic fungi.Compounds 1–8,10,and 11 exhibited antimicrobial activities against some of the tested strains with minimum inhibitory concentration(MIC)values ranging from^2 to 64μg/mL.Compounds 4 and 6 displayed strongest activities among the tested samples and might be used as promising molecules for the development of natural antimicrobial agents.

EQUILIBRIUM PROBLEMS WITH LOWER AND UPPER BOUNDS IN TOPOLOGICAL SPACES

By employing a fixed point theorem due to Ding, Park and Jung, some existence theorems of solutions for equilibrium problems with lower and upper bounds are proved in noncompact topological spaces. These results further answer the open problem raised by Isac, Sehgal and Singh under much weaker assumptions.

On the adjacent vertex-distinguishing acyclic edge coloring of some graphs

A proper edge coloring of a graph G is called adjacent vertex-distinguishing acyclic edge coloring if there is no 2-colored cycle in G and the coloring set of edges incident with u is not equal to the coloring set of edges incident with v, where uv∈ E（G）. The adjacent vertex distinguishing acyclic edge chromatic number of G, denoted by X＇Aa（G）, is the minimal number of colors in an adjacent vertex distinguishing acyclic edge coloring of G. If a graph G has an adjacent vertex distinguishing acyclic edge coloring, then G is called adjacent vertex distinguishing acyclic. In this paper, we obtain adjacent vertex-distinguishing acyclic edge coloring of some graphs and put forward some conjectures.

Dependent task assignment algorithm based on particle swarm optimization and simulated annealing in ad-hoc mobile cloud

In order to solve the problem of efficiently assigning tasks in an ad-hoc mobile cloud( AMC),a task assignment algorithm based on the heuristic algorithm is proposed. The proposed task assignment algorithm based on particle swarm optimization and simulated annealing( PSO-SA) transforms the dependencies between tasks into a directed acyclic graph( DAG) model. The number in each node represents the computation workload of each task and the number on each edge represents the workload produced by the transmission. In order to simulate the environment of task assignment in AMC,mathematical models are developed to describe the dependencies between tasks and the costs of each task are defined. PSO-SA is used to make the decision for task assignment and for minimizing the cost of all devices,which includes the energy consumption and time delay of all devices.PSO-SA also takes the advantage of both particle swarm optimization and simulated annealing by selecting an optimal solution with a certain probability to avoid falling into local optimal solution and to guarantee the convergence speed. The simulation results show that compared with other existing algorithms,the PSO-SA has a smaller cost and the result of PSO-SA can be very close to the optimal solution.

COINCIDENCE THEOREMS INVOKING COMPOSITES OF ACYCLIC MAPPINGS AND APPLICATIONS

Some new coincidence theorems involving a new class of set-valued mappingscontaining composites of acyclic mappings defined on a contractible space are proved.As applications, some existence theorems of maximal elements and solutions of abstract variational inequalities, and best approximation theorems are proved. These theorems improve and generalize a number of known results in recent literature.

Two isomeric compounds of C_(13)-norisoprenoids from Saururus chinensis(Lour.) Baill

Two new isomeric compounds of rare acyclic C13-norisoprenoids, along with two known lignans sauchinone and licarin A, were isolated from the herb of Saururus chinensis （Lour.） Baill. Their structures were elucidated on the basis of spectral analysis.

A version management model of PDM system and its realization

Based on the key function of version management in PDM system, this paper discusses the function and the realization of version management and the transitions of version states with a workflow. A directed aeyclic graph is used to describe a version model. Three storage modes of the directed acyelic graph version model in the database, the bumping block and the PDM working memory are presented and the conversion principle of these three modes is given. The study indicates that building a dynamic product structure configuration model based on versions is the key to resolve the problem. Thus a version model of single product object is built. Then the version management model in product structure configuration is built and the application of version management of PDM syster is presented as a case.

Studies on Heterobinuclear Complexes of Ln^(3+) and Zn^(2+) with Acyclic Polyether Schiff Base

Eight novel heterobinuclear complexes of Ln3+ and Zn2+ with salicylidene diethylene glycol diamine(SALDA) Schiff base (NO3)22H2O(Ln=Pr, Nd, Sm, Gd, Tb, Er, Yb, Y) were synthesized and characterized on the basis of IR and UV, particularly by1H and13C NMR spectra. It is confirmed that the azomethine nitrogen, ethereal oxygen and a part of phenolic oxygen atoms coordinate to the central ions.

Design, synthesis and in vitro evaluation of L-amino acid esters prodrugs of acyclic nucleoside phosphonates as anti-HBV agent

A series of novel L-amino acid esters prodrugs of acyclic nucleoside phosphonates was synthesized and their anti-HBV activity was evaluated in HepG2 2.2.15 cells. Compound 1d exhibited more potent anti-HBV activity and lower cytotoxicity than those of adefovir dipivoxil with EC50 and CC50 values of 0.207 μmol/L and 2530 μmol/L, respectively.

Modified origin-based algorithm for traffic equilibrium assignment problems

Key tactics of origin-based user equilibrium (OUE) algorithm was studied,which involved the algorithm procedure and several implementation issues.To speed up the convergence,update policies of flows,costs and bushes were proposed.The methods of step-size searching and bush construction are proved to be practical.The modified OUE algorithm procedure was also optimized to take the advantage of multi-thread process.Convergence performances were compared with those of other algorithms by different sizes of urban transportation networks.The result shows this modified OUE algorithm is more efficient and consumes less time to achieve the reasonable relative gap in practical applications.

Multi-Class Support Vector Machine Classifier Based on Jeffries-Matusita Distance and Directed Acyclic Graph

Based on the framework of support vector machines （SVM） using one-against-one （OAO） strategy, a new multi-class kernel method based on directed aeyclie graph （DAG） and probabilistic distance is proposed to raise the multi-class classification accuracies. The topology structure of DAG is constructed by rearranging the nodes＇ sequence in the graph. DAG is equivalent to guided operating SVM on a list, and the classification performance depends on the nodes＇ sequence in the graph. Jeffries-Matusita distance （JMD） is introduced to estimate the separability of each class, and the implementation list is initialized with all classes organized according to certain sequence in the list. To testify the effectiveness of the proposed method, numerical analysis is conducted on UCI data and hyperspectral data. Meanwhile, comparative studies using standard OAO and DAG classification methods are also conducted and the results illustrate better performance and higher accuracy of the orooosed JMD-DAG method.

EZDCP:A new static task scheduling algorithm with edge-zeroing based on dynamic critical paths

A new static task scheduling algorithm named edge-zeroing based on dynamic critical paths is proposed. The main ideas of the algorithm are as follows: firstly suppose that all of the tasks are in different clusters; secondly, select one of the critical paths of the partially clustered directed acyclic graph; thirdly, try to zero one of graph communication edges; fourthly, repeat above three processes until all edges are zeroed; finally, check the generated clusters to see if some of them can be further merged without increasing the parallel time. Comparisons of the previous algorithms with edge-zeroing based on dynamic critical paths show that the new algorithm has not only a low complexity but also a desired performance comparable or even better on average to much higher complexity heuristic algorithms.

3D-QSAR Topomer CoMFA Studies on 10 N-Substituted Acridone Derivatives

Topomer CoMFA models have been used to optimize the potency of 15 biologically active acridone derivatives se- lected from the literature. Their 3D chemical structures were sliced into three acyclic R groups, to produce a fragment that is present in each training set. The analysis was successful with 3 as the number of components that provided the highest q2 results: q2 is 0.56, which is the cross-validated coefficient for the specified number of components, giving rise to 0.37 standard error of estimate (q2 stderr), and a conventional coefficient (r2) of 0.82, whose standard error of estimate is 0.24. These results provide structure-activity relationship (sar) among the compounds. The result of the To-pomer CoMFA studies was used to design novel derivatives for future studies.

A Note on Acyclic Edge Colouring of Star Graph Families

A proper edge colouring f of a graph G is called acyclic if there are no bichromatic cycles in the graph. The acyclic edge chromatic number or acyclic chromatic index, denoted by , is the minimum number of colours in an acyclic edge colouring of G. In this paper, we discuss the acyclic edge colouring of middle, central, total and line graphs of prime related star graph families. Also exact values of acyclic chromatic indices of such graphs are derived and some of their structural properties are discussed.