AXISYMMETRIC BENDING OF TWO-DIRECTIONAL FUNCTIONALLY GRADED CIRCULAR AND ANNULAR PLATES

Assuming the material properties varying with an exponential law both in the thick- ness and radial directions, axisymmetric bending of two-directional functionally graded circular and annular plates is studied using the semi-analytical numerical method in this paper. The deflections and stresses of the plates are presented. Numerical results show the well accuracy and convergence of the method. Compared with the finite element method, the semi-analytical nu- merical method is with great advantage in the computational efficiency. Moreover, study on ax- isymmetric bending of two-directional functionally graded annular plate shows that such plates have better performance than those made of isotropic homogeneous materials or one-directional functionally graded materials. Two-directional functionally graded material is a potential alternative to the one-directional functionally graded material. And the integrated design of materials and structures can really be achieved in two-directional functionally graded materials.

Orchestrating Network Functions in Software-Defined Networks

Software.defined networking(SDN) enables third.part companies to participate in the network function innovations. A number of instances for one network function will inevitably co.exist in the network. Although some orchestration architecture has been proposed to chain network functions, rare works are focused on how to optimize this process. In this paper, we propose an optimized model for network function orchestration, function combination model(FCM). Our main contributions are as following. First, network functions are featured with a new abstraction, and are open to external providers. And FCM identifies network functions using unique type, and organizes their instances distributed over the network with the appropriate way. Second, with the specialized demands, we can combine function instances under the global network views, and formulate it into the problem of Boolean linear program(BLP). A simulated annealing algorithm is designed to approach optimal solution for this BLP. Finally, the numerical experiment demonstrates that our model can create outstanding composite schemas efficiently.

A SEQUENCE SPACE DEFINED BY ORLICZ FUNCTIONS

In this paper we define a sequence space using Orlicz functions. We give certain properties and inclusion relations between known sequence spaces and new sequence space.

A CLASS OF MULTIWAVELETS AND PROJECTED FRAMES FROM TWO-DIRECTION WAVELETS

This article aims at studying two-direction refinable functions and two-direction wavelets in the setting R^s, s 〉 1. We give a sufficient condition for a two-direction refinable function belonging to L^2（R^s）. Then, two theorems are given for constructing biorthogonal （orthogonal） two-direction refinable functions in L^2（R^s） and their biorthogonal （orthogonal） two-direction wavelets, respectively. From the constructed biorthogonal （orthogonal） two-direction wavelets, symmetric biorthogonal （orthogonal） multiwaveles in L^2（R^s） can be obtained easily. Applying the projection method to biorthogonal （orthogonal） two-direction wavelets in L^2（R^s）, we can get dual （tight） two-direction wavelet frames in L^2（R^m）, where m ≤ s. From the projected dual （tight） two-direction wavelet frames in L^2（R^m）, symmetric dual （tight） frames in L^2（R^m） can be obtained easily. In the end, an example is given to illustrate theoretical results.

Using the Cooperative Game for Service Placement of Virtual Network Functions

To address the issues that middleboxes as a fundamental part of today's networks are facing, Network Function Virtualization(NFV)has been recently proposed, which in essence asserts to migrate hardware-based middleboxes into software-based virtualized function entities.Due to the demands of virtual services placement in NFV network environment, this paper models the service amount placement problem involving with the resources allocation as a cooperative game and proposes the placement policy by Nash Bargaining Solution(NBS). Specifically,we first introduce the system overview and apply the rigorous cooperative game-theoretic guide to build the mathematical model, which can give consideration to both the responding efficiency of service requirements and the allocation fairness.Then a distributed algorithm corresponding to NBS is designed to achieve predictable network performance for virtual instances placement.Finally, with simulations under various scenarios,the results show that our placement approach can achieve high utilization of network through the analysis of evaluation metrics namely the satisfaction degree and fairness index. With the suitable demand amount of services, the average values of two metrics can reach above 90%. And by tuning the base placement, our solution can enable operators to flexibly balance the tradeoff between satisfaction and fairness of resourcessharing in service platforms.

Service Function Chain in Small Satellite-Based Software Defined Satellite Networks

Software Defined Satellite Networks(SDSN) are proposed to solve the problems in traditional satellite networks, such as time-consuming configuration and inflexible traffic scheduling. The emerging application of small satellite and research of SDSN make it possible for satellite networks to provide flexible network services. Service Function Chain(SFC) can satisfy this need. In this paper, we are motivated to investigate applying SFC in the small satellite-based SDSN for service delivery. We introduce the structure of the multi-layer constellation-based SDSN. Then, we describe two deployment patterns of SFC in SDSN, the Multi-Domain(MD) pattern and the Satellite Formation(SF) pattern. We propose two algorithms, SFP-MD, and SFP-SF, to calculate the Service Function Path(SFP). We implement the algorithms and conduct contrast experiments in our prototype. Finally, we summarize the applicable conditions of two deployment patterns according to the experimental results in terms of hops, delay, and packet loss rate.

Virtualizing Network and Service Functions: Impact on ICT Transformation and Standardization

Virtualization of network/service functions means time sharing network/service（and affiliated）resources in a hyper speed manner.The concept of time sharing was popularized in the 1970s with mainframe computing.The same concept has recently resurfaced under the guise of cloud computing and virtualized computing.Although cloud computing was originally used in IT for server virtualization,the ICT industry is taking a new look at virtualization.This paradigm shift is shaking up the computing,storage,networking,and ser vice industries.The hope is that virtualizing and automating configuration and service management/orchestration will save both capes and opex for network transformation.A complimentary trend is the separation（over an open interface）of control and transmission.This is commonly referred to as software defined networking（SDN）.This paper reviews trends in network/service functions,efforts to standardize these functions,and required management and orchestration.

Service Function Chain Migration in LEO Satellite Networks

With the advancements of software defined network(SDN)and network function virtualization(NFV),service function chain(SFC)placement becomes a crucial enabler for flexible resource scheduling in low earth orbit(LEO)satellite networks.While due to the scarcity of bandwidth resources and dynamic topology of LEO satellites,the static SFC placement schemes may cause performance degradation,resource waste and even service failure.In this paper,we consider migration and establish an online migration model,especially considering the dynamic topology.Given the scarcity of bandwidth resources,the model aims to maximize the total number of accepted SFCs while incurring as little bandwidth cost of SFC transmission and migration as possible.Due to its NP-hardness,we propose a heuristic minimized dynamic SFC migration(MDSM)algorithm that only triggers the migration procedure when new SFCs are rejected.Simulation results demonstrate that MDSM achieves a performance close to the upper bound with lower complexity.

Two-direction refinable functions and twodirection wavelets with high approximation order and regularity

The concept of two-direction refinable functions and two-direction wavelets is introduced.We investigate the existence of distributional(or L2-stable) solutions of the two-direction refinement equation: φ(x)=∑p+kφ(mx-k)+∑p-kφ(k-mx) where m ≥ 2 is an integer. Based on the positive mask {pk+} and negative mask {p-k}, the conditions that guarantee the above equation has compactly distributional solutions or L2-stable solutions are established. Furthermore, the condition that the L2-stable solution of the above equation can generate a two-direction MRA is given. The support interval of φ(x) is discussed amply. The definition of orthogonal two-direction refinable function and orthogonal two-direction wavelets is presented, and the orthogonality criteria for two-direction refinable functions are established. An algorithm for constructing orthogonal two-direction refinable functions and their two-direction wavelets is presented. Another construction algorithm for two-direction L2-refinable functions, which have nonnegative symbol masks and possess high approximation order and regularity, is presented. Finally, two construction examples are given.

An Approach for Network Function Combination Based on Least Busy Placement Algorithm

Recently, integrating Softwaredefined networking(SDN) and network functions virtualization(NFV) are proposed to address the issue that difficulty and cost of hardwarebased and proprietary middleboxes management. However, it lacks of a framework that orchestrates network functions to service chain in the network cooperatively. In this paper, we propose a function combination framework that can dynamically adapt the network based on the integration NFV and SDN. There are two main contributions in this paper. First, the function combination framework based on the integration of SDN and NFV is proposed to address the function combination issue, including the architecture of Service Deliver Network, the port types representing traffic directions and the explanation of terms. Second, we formulate the issue of load balance of function combination as the model minimizing the standard deviations of all servers' loads and satisfying the demand of performance and limit of resource. The least busy placement algorithm is introduced to approach optimal solution of the problem. Finally, experimental results demonstrate that the proposed method can combine functions in an efficient and scalable way and ensure the load balance of the network.

A Software-Defined Approach to IoT Networking

It is foreseen that the Internet of Things (IoT) will comprise billions of connected devices, and this will make the provi?sioning and operation of some IoT connectivity services more challenging. Indeed, IoT services are very different from lega?cy Internet services because of their dimensioning figures and also because IoT services differ dramatically in terms of na?ture and constraints. For example, IoT services often rely on energy and CPU?constrained sensor technologies, regardless of whether the service is for home automation, smart building, e?health, or power or water metering on a regional or national scale. Also, some IoT services, such as dynamic monitoring of biometric data, manipulation of sensitive information, and pri?vacy needs to be safeguarded whenever this information is for?warded over the underlying IoT network infrastructure. This paper discusses how software?defined networking (SDN) can facilitate the deployment and operation of some advanced IoT services regardless of their nature or scope. SDN introduces a high degree of automation in service delivery and operation-from dynamic IoT service parameter exposure and negotiation to resource allocation, service fulfillment, and assurance. This paper does not argue that all IoT services must adopt SDN. Rather, it is left to the discretion of operators to decide which IoT services can best leverage SDN capabilities. This paper only discusses managed IoT services, i.e., services that are op?erated by a service provider.

Optimize the Deployment and Integration for Multicast-Oriented Virtual Network Function Tree

Due to the development of network technology,the number of users is increasing rapidly,and the demand for emerging multicast services is becoming more and more abundant,traffic data is increasing day by day,network nodes are becoming denser,network topology is becoming more complex,and operators’equipment operation and maintenance costs are increasing.Network functions virtualization multicast issues include building a traffic forwarding topology,deploying the required functions,and directing traffic.Combining the two is still a problem to be studied in depth at present,and this paper proposes a two-stage solution where the decisions of these two stages are interdependent.Specifically,this paper decouples multicast traffic forwarding and function delivery.The minimum spanning tree of traffic forwarding is constructed by Steiner tree,and the traffic forwarding is realized by Viterbi-algorithm.Use a general topology network to examine network cost and service performance.Simulation results show that this method can reduce overhead and delay and optimize user experience.

资源碎片感知的服务功能链映射算法

针对网络虚拟化环境中资源碎片问题,提出一种资源碎片感知的服务功能链路由算法。提出一种资源碎片化度量模型,用于定量地测量物理节点和物理链路的资源碎片化程度,将服务功能链映射问题转化为以最小化资源碎片为优化目标的整数线性规划模型,使用分步优化方法,解决动态网络环境中服务功能链映射问题。实验结果表明,与同类算法进行对比,SFC-RFA有效降低了资源碎片率,服务功能链请求接受率提高了12%~26%,资源利用率提高了7%~17%,取得了较好的负载均衡性能。

软件定义无线网络异构服务功能链低功耗部署方法

受到节点性能以及功耗方面的限制,在对无线网络异构服务功能链进行部署时,通常会因缺乏节点重要程度评估而导致部署效果不佳。对此,提出软件定义无线网络异构服务功能链低功耗部署方法。首先通过对网络协议内容进行获取,实现拓扑结构感知,并构建出节点重要度与节点链路数目之间的相关关系,对网络节点的重要度进行计算。然后将原始服务功能链拆分为多个独立的服务功能,并以节点综合度最高以及网络功耗最低构建出的目标函数作为映射方案求解途径,将服务功能映射到物理节点上。利用SDN控制器的编程接口,将功能链分解与映射的结果转化为网络配置指令。最后构建交换机的流量需求信息与待部署节点之间的映射关系,从而实现低功耗部署。在实验中,对提出的服务功能链部署方法进行了部署效果的检验。最终的测试结果表明,采用提出的方法对服务功能链进行模拟部署后,软件定义无线网络的功耗值更低,具备较为理想的部署效果。

天地一体化网络关键技术研究综述

作为地面网络的补充和延伸,卫星网络有助于加速弥合区域间的数字鸿沟,扩展地面网络的覆盖和服务范围.然而卫星网络拓扑动态性高、传播时延大、星上计算能力和存储能力均受限,因此实现卫星网络与地面网络的有机融合,构建覆盖全球的天地一体化网络面临路由扩展性、传输稳定性等技术挑战.针对天地一体化网络的研究挑战,从网络架构、路由、传输和基于组播的内容分发等方面介绍了国内外的研究现状,并展望了天地一体化网络的发展趋势.

基于ConvLSTM融合RMAPS-NOW数据的雷达回波外推研究

雷达回波外推是临近预报、人工影响天气作业及效果评估的主要参考依据之一,快速准确的回波外推技术一直是雷达气象领域的研究热点。近年来,基于深度学习的时空序列预测模型在雷达回波外推中得到了广泛应用。然而,这些外推网络架构的输入大多用16级伪彩色雷达回波强度产品转化而来的灰度图,丢失了许多回波细节,并且随着外推时间延长,误差不可避免地增大。回波的生消、移动、演变与天气背景紧密相关,因此,将北京城市气象研究院研发的新一代快速更新多尺度资料分析和预报系统的临近数值预报子系统(RMAPS-NOW)初始零场的部分物理量产品融入华北雷达拼图原始数据,构建多个雷达单元(Radar cells),并将这些雷达单元作为输入,基于卷积长短期记忆网络(ConvLSTM),设计了一个多通道雷达回波外推网络架构(MR-ConvLSTM)。另外,考虑到卷积算法的平滑性,构建了自定义损失函数,增加回波强度的时空权重进行时空衰减订正。选取(40.65°—41.65°N,114°—115.4°E)内2018—2021年的6—9月共13000组华北雷达组合反射率因子拼图及RMAPS-NOW初始零场数据,其中的80%共10400组为训练集,20%共2600组为测试集。引入的物理量包括多个高度层的u、v风(1350 m),相对湿度(RH,150 m),水平散度(1350 m)等,基于ConvLSTM及MR-ConvLSTM加自定义损失函数,分别训练得到5个雷达回波外推模型。采用临界成功指数(CSI)、命中率(POD)、虚警率(FAR)作为评价指标,利用测试集对所有模型进行评估。基于引入物理量的MR-ConvLSTM训练得到的模型在20、30、35 dBz反射率阈值下,比未引入物理量的基于ConvLSTM的外推模型CSI值平均高4.67%、13.8%、5.98%,POD值平均高3.1%、7.68%、8.38%,FAR值平均低6.37%、8.54%、10.17%,同时引入3种物理量(RH、u、v)的外推模型在不同阈值的各项指标中综合表现最好,其CSI、 POD值在3种不同阈值下比未引入物理量模型平均高16.01%、13.38%,FAR值平均低14.88%。从模型应用的个例可视化也可以看出,引入物理量后有效提升了雷达回波外推的准确度,证明基于MR-ConvLSTM架构训练的雷达回波外推模型有较强的泛化能力。

自定义函数拟合在乙酸乙酯皂化反应实验中的应用

数据处理方法对乙酸乙酯皂化反应速率常数测定实验的结果影响较大。为了避免外推法作图、拟合公式与实验公式不匹配等处理方法带来的误差,本文根据各物理化学参数之间的关系推导得到新的函数,在Origin软件中用自定义函数对实验数据进行处理,一次拟合即可获得反应速率常数以及实验中不能直接测得的反应起始和平衡电导率值。对比分析了自定义函数拟合、多项式拟合和指数函数拟合得到的实验结果,表明自定义函数拟合能够达到最优的拟合效果,实验结果误差最小。数据处理方法的改进,即锻炼了学生综合运用物理化学、数学和计算机知识处理实验数据的能力,又培养了学生的科学思维。

基于IMPACT模式的延续性护理在老年2型糖尿病合并冠心病患者中的应用效果

目的:观察基于确定-定义-产生-应用-计算-跟踪(IMPACT)模式的延续性护理在老年2型糖尿病合并冠心病患者中的应用效果。方法:选取2020年8月至2022年8月该院收治的94例老年2型糖尿病合并冠心病患者进行前瞻性研究,采用随机数字表法将其分为观察组与对照组各47例。对照组采取常规护理,观察组采取基于IMPACT模式的延续性护理。比较两组护理前后血糖指标[餐后2 h血糖(2hPG)、空腹血糖(FBG)、糖化血红蛋白(HbA1c)]水平、心功能指标[左心室射血分数(LVEF)、左心室短轴缩短率(FS)、左心室收缩末期内径(LVESD)、左心室舒张末期内径(LVEDD)]水平、健康行为[健康促进生活方式量表Ⅱ(HPLP-Ⅱ)]评分、生命质量[2型糖尿病患者生存质量量表(DMQLS)]评分和护理满意度。结果:护理后,两组2hPG、FBG、HbA1c水平均低于护理前,且观察组低于对照组,差异有统计学意义(P<0.05);两组LVEF、FS水平均高于护理前,且观察组高于对照组,两组LVEDD、LVESD水平均低于护理前,且观察组低于对照组,差异有统计学意义(P<0.05);两组压力管理、健康责任感、人际关系、营养、体育运动和精神成长等HPLP-Ⅱ评分均高于护理前,且观察组高于对照组,差异有统计学意义(P<0.05);两组疾病、生理、心理、社会、满意度等DMQLS评分均高于护理前,且观察组高于对照组,差异有统计学意义(P<0.05);观察组护理满意度为95.74%(45/47),高于对照组的82.98%(39/47),差异有统计学意义(P<0.05)。结论:基于IMPACT模式的延续性护理应用于老年2型糖尿病合并冠心病患者中可降低血糖指标水平,改善心功能指标水平,提高健康行为评分、生命质量评分和护理满意度,其效果优于常规护理。

软件定义并行多径SFC编排

网络功能虚拟化(Network Functions Virtualization, NFV)技术可以通过动态实例化以及根据随时间变化的服务需求去动态地部署虚拟网络功能。基于NFV的多域网络切片中服务功能链(Service Function Chaining, SFC)的编排问题研究缺乏考虑多域场景,大多数启发式算法仅仅考虑了上界,SFC映射策略无法满足低时延高可靠要求。建立了面向并行业务流服务时延优化的数学模型,并进一步基于拉格朗日松弛法提出了一种考虑了下界的启发式SFC映射策略,可以有效地降低时延,提高服务的可靠性。与多租户边缘网络中可靠的SFC编排算法以及多路径低延迟SFC编排算法相比,所提算法平均包交付率分别提升了3.3%和7.4%,平均资源消耗分别降低了9%和19.2%。

核电主蒸汽阀站中电磁先导阀的动态响应仿真研究

针对核电主蒸汽阀站中关键部件之一——大气释放阀前置隔离阀在实际工况中常出现响应超时的问题,采用数值仿真软件Fluent中的动网格以及用户自定义函数技术,对控制其启闭过程的电磁先导阀动态响应过程进行了研究。首先,研究了电磁先导阀中先导结构的动态响应过程以及阀杆的受力情况;然后,研究了电磁先导阀中主阀的动态响应过程以及主阀泄压时阀内的压力和速度分布情况;最后,综合两个动态过程,分析了电磁先导阀整阀的运动时间。研究结果表明,电磁先导阀的运动时间为8.5 ms,其中先导结构的运动时间占比较小,85%的时间集中在电磁先导阀主阀动作过程。该研究结果可对前置隔离阀响应时间的优化提供参考。