Riesz空间分数阶扩散方程的分数阶中心差分加权离散格式

在有限区域内考虑带齐次Dirichlet边界条件的Riesz空间分数阶扩散方程的初边值问题,利用分数阶中心差分对空间方向进行离散,在时间方向上用隐式和显式Euler格式的加权平均进行离散,构造了空间2阶、时间γ阶(γ=1,2)的全离散加权差分格式.利用函数的单调性证明了当加权因子0≤θ≤1/2时差分离散格式是无条件稳定的,当1/2<θ≤1时差分离散格式是条件稳定的,并给出了稳定的条件.证明了相应差分离散格式的收敛性.用实际数值算例验证了差分离散格式的有效性.

用于计算离散分数阶傅里叶变换的MA-CDFRFT算法改进

基于中心类型DFT矩阵特征分解的MA-CDFRFT(Multiangle Centered Discrete Fractional Fourier Transform)算法在计算一组离散分数阶傅里叶变换DFRFT(Discrete Fractional Fourier Transform)时充分利用FFT运算来减小运算量.结合偶数点离散傅里叶变换DFT(Discrete Fourier Transform)运算的对称性原理,通过数学推导将MA-CDFRFT算法中的一维对称性扩展到频率和变换阶数的二维平面上.利用这个二维对称性原理,改进算法将原算法的主要计算量减小了一半左右.仿真测试结果证明了改进算法的正确性.

Optimization on the Conversion of Bamboo Shoot Shell to Levulinic Acid with Environmentally Benign Acidic Ionic Liquid and Response Surface Analysis

Levulinic acid（LA） has been identified as a promising green,biomass derived platform chemical.Response surface analysis（RSA） with a four-factor-five-level central composite design（CCD） was applied to optimize the hydrolysis conditions for the conversion of bamboo（Phyllostachys Praecox f.preveynalis） shoot shell（BSS） to LA catalyzed with ionic liquid [C4mim]HSO4.The effects of four main reaction parameters including temperature,time,C[C4mim]HSO4（initial [C4mim]HSO4 concentration） and XBSS（initial BSS intake） on the hydrolysis reaction for yield of LA were analyzed.A quadratic equation model for yield of LA was established and fitted to the data with an R2 of 0.9868,and effects of main factors and their corresponding relationships were obtained with RSA.Model validation and results of CCD showed good correspondence between actual and predicted values.The analysis of variance（ANOVA） of the results indicated that the yield of LA in the range studied was significantly（P＆lt;0.05） affected by the four factors.The optimized reaction conditions were as follows：temperature of 145 ℃,time of 103.8 min,C[C4mim]HSO4 of 0.9 mol.L-1 and XBSS of 2.04%（by mass）,respectively.A high yield [（71±0.41）%（by mol）,triplicate experiment] was obtained at the optimum conditions of temperature of 145 ℃,time of 104 min,C[C4mim]HSO4 of 0.9 mol.L-1 and XBSS of 2%（by mass）,which obtained from the real experiments,concurred with the model prediction [73.8%（by mol） based on available C6 sugars in BSS or 17.9%（by mass） based on the mass of BSS],indicating that the model was adequate for the hydrolysis process.

Delay-Differentiated Scheduling in Optical Packet Switches for Cloud Data Centers

We consider differentiated timecritical task scheduling in a N×N input queued optical packet s w itch to ens ure 100% throughput and meet different delay requirements among various modules of data center. Existing schemes either consider slot-by-slot scheduling with queue depth serving as the delay metric or assume that each input-output connection has the same delay bound in the batch scheduling mode. The former scheme neglects the effect of reconfiguration overhead, which may result in crippled system performance, while the latter cannot satisfy users' differentiated Quality of Service(Qo S) requirements. To make up these deficiencies, we propose a new batch scheduling scheme to meet the various portto-port delay requirements in a best-effort manner. Moreover, a speedup is considered to compensate for both the reconfiguration overhead and the unavoidable slots wastage in the switch fabric. With traffic matrix and delay constraint matrix given, this paper proposes two heuristic algorithms Stringent Delay First(SDF) and m-order SDF(m-SDF) to realize the 100% packet switching, while maximizing the delay constraints satisfaction ratio. The performance of our scheme is verified by extensive numerical simulations.

Resource Allocation with Dynamic Substrate Network in Data Centre Networks

The resource allocation problem in data centre networks refers to a map of the workloads provided by the cloud users/tenants to the Substrate Network(SN)which are provided by the cloud providers.Existing studies consider the dynamic arrival and departure of the workloads,while the dynamics of the substrate are ignored.In this paper,we first propose the resource allocation with the dynamic SN,and denote it as GraphMap-DS.Then,we propose an efficient mapping algorithm for GraphMap-DS.The performance of the proposed algorithm is evaluated by performing simulation experiments.Our results show that the proposed algorithm can effectively solve the GraphMap-DS.

Improving MapReduce Performance by Balancing Skewed Loads

MapReduce has emerged as a popular computing model used in datacenters to process large amount of datasets.In the map phase,hash partitioning is employed to distribute data that sharing the same key across data center-scale cluster nodes.However,we observe that this approach can lead to uneven data distribution,which can result in skewed loads among reduce tasks,thus hamper performance of MapReduce systems.Moreover,worker nodes in MapReduce systems may differ in computing capability due to(1) multiple generations of hardware in non-virtualized data centers,or(2) co-location of virtual machines in virtualized data centers.The heterogeneity among cluster nodes exacerbates the negative effects of uneven data distribution.To improve MapReduce performance in heterogeneous clusters,we propose a novel load balancing approach in the reduce phase.This approach consists of two components:(1) performance prediction for reducers that run on heterogeneous nodes based on support vector machines models,and(2) heterogeneity-aware partitioning(HAP),which balances skewed data for reduce tasks.We implement this approach as a plug-in in current MapReduce system.Experimental results demonstrate that our proposed approach distributes work evenly among reduce tasks,and improves MapReduce performance with little overhead.

Submaximal oxygen uptake kinetics, functional mobility, and physical activity in older adults with heart failure and reduced ejection fraction

Background Submaximal oxygen uptake measures are more feasible and may better predict clinical cardiac outcomes than maximal tests in older adults with heart failure （HF）. We examined relationships between maximal oxygen uptake, submaximal oxygen kinetics, fianctional mobility, and physical activity in older adults with HF and reduced ejection fraction. Methods Older adults with HF and reduced ejection fraction （n = 25, age 75 ：i： 7 years） were compared to 25 healthy ageand gender-matched controls. Assessments included a maximal treadmill test for peak oxygen uptake （VO2p^ak）, oxygen uptake kinetics at onset of and on recovery from a submaximal treadmill test, functional mobility testing [Get Up and Go （GUG）, Comfortable Gait Speed （CGS）, Unipedal Stance （US）], and self-reported physical activity （PA）. Results Compared to controls, HF had worse performance on GUG, CGS, and US, greater delays in submaximal oxygen uptake kinetics, and lower PA. In controls, VO2peak was more strongly associated with functional mobility and PA than submaximal oxygen uptake kinetics. In HF patients, submaximal oxygen uptake kinetics were similarly associated with GUG and CGS as VO2peak, but weakly associated with PA. Conclusions Based on their mobility performance, older HF patients with reduced ejection fraction are at risk for adverse functional outcomes. In this population, submaximal oxygen uptake measures may be equivalent to VO2 peak in predicting functional mobility, and in addition to being more feasible, may provide better insight into how aerobic function relates to mobility in older adults with HF.

Heuristic Virtual Machine Allocation for Multi-Tier Ambient Assisted Living Applications in a Cloud Data Center

Cloud computing provides the essential infrastructure for multi-tier Ambient Assisted Living(AAL) applications that facilitate people's lives. Resource provisioning is a critically important problem for AAL applications in cloud data centers(CDCs). This paper focuses on modeling and analysis of multi-tier AAL applications, and aims to optimize resource provisioning while meeting requests' response time constraint. This paper models a multi-tier AAL application as a hybrid multi-tier queueing model consisting of an M/M/c queueing model and multiple M/M/1 queueing models. Then, virtual machine(VM) allocation is formulated as a constrained optimization problem in a CDC, and is further solved with the proposed heuristic VM allocation algorithm(HVMA). The results demonstrate that the proposed model and algorithm can effectively achieve dynamic resource provisioning while meeting the performance constraint.

Analysis of Cooling Characteristics in Datacenter Using Outdoor Air Cooling

Advancement of the information society has proceeded with the development of information and communication technology, and a demand on a data center has increased. In such a situation, the number of servers is increasing in a data center. Thus, the heat density in a data center is much higher than that of usual offices. And typically, almost 40% of the total power consumption is used for cooling servers in a data center. Thus, cooling effectiveness is one of the most important factors in evaluating the value of the data center. The data center taken up in this paper is located in Ishikari, where is a cold district in Japan. Using the cool outdoor air for cooling servers helps us to cut the power consumption for cooling. This paper first assesses the efficiency of Ishikari data center measuring the temperature of seven parts in a building where the cooling air flowing. Second, this paper describes the most efficient method for the operation and estimates 1.11 of PUE （power usage effectiveness）.

建构“以学习为中心的评估”——面向未来的中小学评估转型探析

当下,我国中小学的评估在很大程度上仍将重心置于学生的考试分数上,而不是放在学生的学习上。建构"以学习为中心的评估",有利于推动中小学评估实现转型性变革,从"为评而学"走向"为学而评",从"造成威胁"走向"给予希望",从"强调分数"走向"支持可持续学习",进而突破"以分数为中心的评估"困局,充分释放评估促进学生学习与终身发展的作用。"以学习为中心的评估"具有五大特征:评估目的体现整体观照过去、当下和未来向度的学习;评估活动强调学生参与,让学生也成为评估主体,参与研制评估学习的标准并基于评估标准开展评估;评估内容指向认知、情意、自我调节和社会交往四维度的学习;评估方法力求多元整合,既综合运用多种已有方法,也创生一些新型方法,打破单一使用某种方法的习惯;评估反馈聚焦改进提升,强调反馈能被学生理解、认同、运用并带来学习上的改进。推进"以学习为中心的评估"其关键在于,将评估融入师生的教与学活动,教与学的过程成为评估过程,促进师生成长为"教-学-评整合"的实践者。师生在教与学的目标研制、情况分析、策略选择、效果考察及改进路径等方面开展一系列创新,进而落实和深化"以学习为中心的评估"。

Numerical Investigation of Centerline Curvature Effects on a Compact S-shaped Intake

Taking into account stealth, structure and maintenance, ultra-compact S-shaped intake has been widely used in modem vehicles. In this paper a series of steady numerical simulation were carried out to investigate the complex flow mechanism in s-shaped intake, particular attention was given to examining the effect of centerline curvature on the performance and flowfield of an ultra-compact S-shaped intake. In order to validate the multi-block model, the computational results for Royal Aircraft Establishment intake 2129-M2129 which had modest centerline cur- vature distribution were corrected with available experimental test data. The numerical simulation results agreed fairly well with the experimental data, and the computational method was then used to investigate the effects of different centerline curvature distributions on performance and flow field in compact S-shaped intake. Detailed analyses of the flow visualization had exposed the different flow topologies between the cases with different cen- terline curvature. It was found that different centerline curvature distributions changed the initial location and the size of separation bubble, as well as the strength of two counter-rotating vortices at the entrance of engine.

Medicinals with properties of warming Yang and tonifying Qi in terms of Traditional Chinese Medicine: their effects on left ventricular ejection fraction and aldosterone in rats with induced failure heart

OBJECTIVE: To investigate on Left ventricular ejection fraction value and aldosterone of two medicinals of Traditional Chinese Medicine(TCM) with the properties of warming Yang and tonifying Qi in terms of TCM theory.METHODS: An animal model of coronary ligation of heart failure after myocardial infarction was employed to study the influence of these two kinds of drugs on three batches of rats. On the basis of the average score of left ventricle ejection fraction during the investigation, there were some different groups, including Wen Yang(the warming Yang)group, Yi Qi(tonifying Qi) group, Wen Yang and Yi Qi group, captopril group, digoxin group. In additional, an artificial operation group was set for compari-son. The systemic intervention using these medicinal and drugs was taken effects on the 2nd day after the operation of myocardial infraction(MI) with once a day. At week one, two, and four after the MI treatment, evaluated were EF values, and ferritin,angiotensin-II and aldosterone in the rats' plasma.RESULTS: At week one and week two, the medicinal of Wen Yang, Yi Qi, Wen Yang pluse Yi Qi, and digoxin could improve left ventricular ejection fraction in rats with heart failure; Compared to the model group, captopril Left ventricular EF value increased, but there was not significant. At week four,heart failure and left ventricular EF values was improved in the intervention group and the other four captopril drug intervention. At week one in the rats with drug intervention, the medicinals of Yi Qi, Wen Yang plus Yi Qi, and captopril could inhibit activation in vivo hormone aldosterone in heart failure rats; aldosterone in Wen Yang group and digoxin group were not different from that in the model group at week two and four.CONCLUSION: Chinese medicinals with properties of Wen Yang, Yi Qi have significant effect on improving left ventricular EF in rats with heart failure; compared to Yi Qi medicinals, Wen Yang medicinals that inhibit the effectiveness of the time required for the activation of the role of aldosterone. The medicinals of Wen Yang and Yi Qi seems better by inhibiting the activation of the hormone aldosterone after failing to inhibit ventricular remodeling to improve heart failure.

通信枢纽楼能耗运行分析研究

如何在业务量不断增加,电源容量无法扩容的情况下,更好地解决供电能力紧张、机房装机位不足、机房散热等问题,是本论文的研究意义所在。本文通过对S省通信枢纽楼能耗运行分析,给出以上难点的合理化建议和建设指导原则。

Hopf bifurcation analysis in a turbidostat model with Beddington.DeAngelis functional response and discrete delay

In this paper, regarding the time delay as a bifurcation parameter, the stability and Hopf bifurcation of the model of competition between two species in a turbidostat with Beddington-DeAngelis functional response and discrete delay are studied. The Hopf bifurcations can be shown when the delay crosses the critical value. Furthermore, based on the normal form and the center manifold theorem, the type, stability and other properties of the bifurcating periodic solutions are determined. Finally, some numerical simulations are given to illustrate the results.

Bifurcation behaviors analysis of a plankton model with multiple delays

A mathematical model describing the dynamics of toxin producing phytoplankton- zooplankton interaction with instantaneous nutrient recycling is proposed. We have explored the dynamics of plankton ecosystem with multiple delays; one due to gestation period in the growth of phytoplankton population and second due to the delay in toxin liberated by TPP. It is established that a sequence of Hopf bifurcations occurs at the interior equilibrium as the delay increases through its critical value. The direction of the Hopf bifurcation and the stability of the bifurcating periodic solutions are determined using the theory of normal form and center manifold. Meanwhile, effect of toxin on the stability of delayed plankton system is also established numerically. Finally, numerical simulations are carried out to support and supplement the analytical findings.

Bifurcation analysis in a predator-prey model for the effect of delay in prey

In this paper, we study dynamics in a predator-prey model with delay, in which predator can be infected, with particular attention focused on nonresonant double Hopf bifurca- tion. By using center manifold reduction methods, we obtain the equivalent normal forms near a double Hopf critical point in this system. Moreover, bifurcations are classified in a two-dimensional parameter space near the critical point. Numerical simulations are presented to demonstrate the applicability of the theoretical results.