Defending Against Link Failure in Virtual Network Embedding Using a Hybrid Scheme

Nowadays network virtualization is utterly popular.As a result,how to protect the virtual networks from attacking on the link is increasingly important.Existing schemes are mainly backup-based,which suffer from data loss and are helpless to such attacks like data tampering.To offer high security level,in this paper,we first propose a multipath and decision-making(MD) scheme which applies multipath simultaneously delivery and decision-making for protecting the virtual network.Considering different security requirement for virtual link,we devise a hybrid scheme to protect the virtual links.For the critical links,MD scheme is adopted.For the other links,we adopt the Shared Backup Scheme.Our simulation results indicate the proposed scheme can significantly increase the security level of the critical link high in the loss of less acceptance ratio.

A New Hybrid WENO Scheme with the High-Frequency Region for Hyperbolic Conservation Laws

In this paper,a new kind of hybrid method based on the weighted essentially non-oscillatory(WENO)type reconstruction is proposed to solve hyperbolic conservation laws.Comparing the WENO schemes with/without hybridization,the hybrid one can resolve more details in the region containing multi-scale structures and achieve higher resolution in the smooth region;meanwhile,the essentially oscillation-free solution could also be obtained.By adapting the original smoothness indicator in the WENO reconstruction,the stencil is distinguished into three types:smooth,non-smooth,and high-frequency region.In the smooth region,the linear reconstruction is used and the non-smooth region with the WENO reconstruction.In the high-frequency region,the mixed scheme of the linear and WENO schemes is adopted with the smoothness amplification factor,which could capture high-frequency wave efficiently.Spectral analysis and numerous examples are presented to demonstrate the robustness and performance of the hybrid scheme for hyperbolic conservation laws.

A High Resolution Low Dissipation Hybrid Scheme for Compressible Flows

In this paper, an efficient hybrid shock capturing scheme is proposed to obtain accurate results both in the smooth region and around discontinuities for compressible flows. The hybrid algorithm is based on a fifth-order weighted essentially non-oscillatory （WENO） scheme in the finite volume form to solve the smooth part of the flow field, which is coupled with a characteristic-based monotone upstream-centered scheme for conservation laws （MUSCL） to capture discontinuities. The hybrid scheme is intended to combine high resolution of MUSCL scheme and low dissipation of WENO scheme. The two ingredients in this hybrid scheme are switched with an indicator. Three typical indicators are chosen and compared. MUSCL and WENO are both shock capturing schemes making the choice of the indicator parameter less crucial. Several test cases are carried out to investigate hybrid scheme with different indicators in terms of accuracy and efficiency. Numerical results demonstrate that the hybrid scheme in the present work performs well in a broad range of problems.

A Stability Analysis of Hybrid Schemes to Cure Shock Instability

The carbuncle phenomenon has been regarded as a spurious solution produced by most of contact-preserving methods.The hybrid method of combining high resolution flux with more dissipative solver is an attractive attempt to cure this kind of non-physical phenomenon.In this paper,a matrix-based stability analysis for 2-D Euler equations is performed to explore the cause of instability of numerical schemes.By combining the Roe with HLL flux in different directions and different flux components,we give an interesting explanation to the linear numerical instability.Based on such analysis,some hybrid schemes are compared to illustrate different mechanisms in controlling shock instability.Numerical experiments are presented to verify our analysis results.The conclusion is that the scheme of restricting directly instability source is more stable than other hybrid schemes.

A HYBRID FINITE ELEMENT SCHEME FOR INVISCID SUPERSONIC FLOWS

A hybrid monotonous finite element algorithm is developed in the present paper, based on a second-order-accurate finite element scheme and a first-accurate monotonous one derived from the former by a unilateral lumping procedure in one dimensional case. The switch functions for the two dimensional Euler equation system are constructed locally, based on the gradient of the flow field, with special consideration on the information from neighboring elements. Examples show that the new scheme can eliminate oscillations near strong shocks obviously.

A TVD-WAF-based hybrid finite volume and finite difference scheme for nonlinearly dispersive wave equations

A total variation diminishing-weighted average flux （TVD-WAF）-based hybrid numerical scheme for the enhanced version of nonlinearly dispersive Boussinesq-type equations was developed. The one-dimensional governing equations were rewritten in the conservative form and then discretized on a uniform grid. The finite volume method was used to discretize the flux term while the remaining terms were approximated with the finite difference method. The second-order TVD-WAF method was employed in conjunction with the Harten-Lax-van Leer （HLL） Riemann solver to calculate the numerical flux, and the variables at the cell interface for the local Riemann problem were reconstructed via the fourth- order monotone upstream-centered scheme for conservation laws （MUSCL）. The time marching scheme based on the third-order TVD Runge- Kutta method was used to obtain numerical solutions. The model was validated through a series of numerical tests, in which wave breaking and a moving shoreline were treated. The good agreement between the computed results, documented analytical solutions, and experimental data demonstrates the correct discretization of the governing equations and high accuracy of the proposed scheme, and also conforms the advantages of the proposed shock-capturing scheme for the enhanced version of the Boussinesq model, including the convenience in the treatment of wave breaking and moving shorelines and without the need for a numerical filter.

Likelihood Inference under Generalized Hybrid Censoring Scheme with Comp eting Risks

Statistical inference is developed for the analysis of generalized type-Ⅱ hybrid censoring data under exponential competing risks model. In order to solve the problem that approximate methods make unsatisfactory performances in the case of small sample size,we establish the exact conditional distributions of estimators for parameters by conditional moment generating function(CMGF). Furthermore, confidence intervals(CIs) are constructed by exact distributions, approximate distributions as well as bootstrap method respectively,and their performances are evaluated by Monte Carlo simulations. And finally, a real data set is analyzed to illustrate all the methods developed here.

Hybrid Mapping Scheme for Recent Orthogonal FDMA Schemes

Single-carrier frequency-division multiple access (SC-FDMA) and orthogonal frequency division multiple access (OFDMA) systems are new orthogonal multiple access systems. They have been adopted in the 3GPP long term evolution (3GPP-LTE). In these systems, there are only two types of subcarrier mapping schemes which are the interleaved and the localized. So, introducing a new subcarrier mapping scheme is an important issue, which is the main objective of this paper. In this paper, a hybrid subcarrier mapping scheme is proposed and examined for the SC-FDMA system. Monte Carlo simulations are performed to compare the performance of the proposed scheme with that of the interleaved and the localized schemes. It is shown that a hybrid scheme provides better performance than that of the localized and the same performance as that of the interleaved scheme and increased robustness to carrier frequency offset (CFO) at the expense of increased envelope fluctuations.

HHR:Hierarchical Hybrid Routing Scheme for Information-Centric Network

Publish/subscribe(pub/sub) paradigm is the main communication model for Information-Centric Network(ICN) proposals.A key issue for pub/sub system is how to route the content objects to the correct subscribers,and ICN is no exception.ICN network would be divided into core domain and many edge domains as today's internet does.HHR(Hierarchy Hybrid Routing scheme) is presented for ICN:A Chord-like routing scheme is used in core domain,while edge domains routing structure can be classified into three categories,Local Routing(LR),Delivery of Local Publication to Core domain(DLPC),and Remote Publication Routing into edge domain(RPR).LR can be decided by each edge domain,which determined by many factors,such as locality characteristic for pub/sub information and local policies.A hierarchical routing algorithm is proposed to solve DLPC and RPR simultaneously.Simulation results demonstrate that HHR can be fast deployed,and can be applied in large scale network or dynamic subscription environment.

带有预验证机制的区块链动态共识算法

委员会共识和混合共识通过选举委员会来代替全网节点完成区块验证,可有效加快共识速度,提高吞吐量,但恶意攻击和收买易导致委员会发生腐败问题,严重时将影响共识结果甚至造成系统瘫痪.现有工作虽引入信誉机制降低委员会节点腐败的可能性,但开销大、可信度低且无法降低腐败问题对系统的影响.提出一种带有预验证机制的区块链动态共识算法(DBCP),通过预验证机制在较小开销的前提下对委员会进行可靠的信誉评估,及时淘汰委员会中的恶意节点.若腐败问题已影响到共识结果,DBCP会通过动态共识将区块验证权转移到全网节点,并淘汰给出错误意见的委员会节点,避免系统瘫痪.若委员会通过迭代达到高可信状态,则DBCP会将区块验证权交由委员会,全网节点将认同委员会的共识结果,并不再对区块进行验证,进而加快共识速度.经实验验证,DBCP的吞吐量与比特币相比提升了两个数量级,且与Byzcoin相近,可在一个出块周期内快速应对委员会腐败问题,安全性优于Byzcoin.

A density-functional-theory-based and machine-learning-accelerated hybrid method for intricate system catalysis

Being progressively applied in the design of highly active catalysts for energy devices,machine learning(ML)technology has shown attractive ability of dramatically reducing the computational cost of the traditional density functional theory(DFT)method,showing a particular advantage for the simulation of intricate system catalysis.Starting with a basic description of the whole workflow of the novel DFT-based and ML-accelerated(DFT-ML)scheme,and the common algorithms useable for machine learning,we presented in this paper our work on the development and performance test of a DFT-based ML method for catalysis program(DMCP)to implement the DFT-ML scheme.DMCP is an efficient and user-friendly program with the flexibility to accommodate the needs of performing ML calculations based on the data generated by DFT calculations or from materials database.We also employed an example of transition metal phthalocyanine double-atom catalysts as electrocatalysts for carbon reduction reaction to exhibit the general workflow of the DFT-ML hybrid scheme and our DMCP program.

作战仿真混合实验方案设计研究

作战仿真实验方案设计指的是基于基准的作战想定,利用各种实验设计方法对实验因子的取值进行抽样,形成一组实验方案,供后续仿真使用。作战仿真的复杂性包括实验因子数目众多,因子类型多样,既有连续数值类型,又有离散数值类型,这对高效的混合实验设计方法提出了迫切的需求。针对这些需求,对作战仿真混合实验方案设计技术展开了研究。对实验设计方法做了简单的分类和综述,给出了3种混合实验方案设计方法的流程及其优缺点分析;介绍了一个面向作战仿真的实验设计系统,包括软件架构设计、功能组成及实验设计流程;以一个作战想定为例,演示和分析了3种混合实验方案设计方法的具体应用。上述方法和工具将有效指导复杂作战仿真中具有离散和混合类型因子的实验设计问题,并在多个仿真项目得到了应用和验证。

混合驱动绞车方案设计及现场试验

为了解决现有煤矿运输绞车普遍存在的操作困难,调速性能差的问题,设计了一种混合驱动绞车。首先,根据实际生产需求,结合现有绞车技术,提出了混合驱动绞车的总体设计。然后,对各部位分别进行结构与原理设计。最后,根据方案设计,通过现场试验验证设计的绞车各种性能,为以后的实际生产提供理论依据。

基于重传错误率估计的自适应HARQ

自适应混合自动重传请求(hybrid automatic repeat request,HARQ)系统的性能与每次传输中的调制与编码方案(modulation and coding scheme,MCS)、发送功率选择密切相关,通过优化重传时的MCS及发送功率可以提升HARQ系统的吞吐率并降低能耗。由于不同MCS传输合并后的译码性能没有闭式解,这导致自适应HARQ优化问题不易解决。首先基于译码的判决域半径给出了一种HARQ合并后译码错误率的近似公式,进而提出了多种能权衡吞吐率和能耗性能的自适应HARQ优化策略。仿真结果验证了所提错误率估计方法的可靠性以及所提自适应HARQ的性能。与传统HARQ方案相比,所提方案能同时提高吞吐率、降低能耗,实现更好的吞吐率与能耗的性能折中。

基于串联式混合动力的无人车功率控制系统设计

介绍了串联式混合动力的无人车辆功率控制系统设计方案,分析了车辆在不同行驶工况下的功率匹配方案和控制策略,针对降速和制动中容易出现的功率匹配性问题提出了解决措施,整体方案已成功在实车上进行了应用。

HybridLT算法的改进及其收敛性分析

HybridLT法是一种解决组合优化问题的新方法 .与现存的Hopfield网络比较 ,这种方法有几个优点 :它不仅能用于二次函数 ,还能用于非二次函数 ;另外 ,在控制人为的加权参数时 ,它减少了对外部的依赖 .文中对原算法进行了改进 ,使其能更快找到准确的最优点 ,并且对迭代方法做了收敛性分析 ,给出了收敛的必要条件和充分条件 .从而说明HybridLT方法是可行的 ,是一种适用于很多类型组合优化问题的有效方法 .

Hybrid assessment of pre-blasting weakening to horizontal section top coal caving (HSTCC) in steep and thick seams

Horizontal section top-coal(HSTCC)caving offers a powerful method to efficiently excavate rude coal in steep and thick seams,and pre-blasting weakening has a profound effect on pursuing great production,high efficiency and good benefit under particular conditions like a small-scale working face with large-scale sectional caving height.+564-level HSTCC working face in B3–6coal seams of Jiangou Colliery in Urumqi was taken as study case for in situ industrial experiment.Total thickness of seams in the study case is about 50.0 m and average angel here is over 83°.In the industrial experiments,at first we adopted continuous charge machine and emulsion matrix explosive to substitute for traditional blasting schemes for specific geological settings in the study case.Hybrid analyses and assessments with blasting crack propagation analysis,abutment pressure monitoring prediction and economical benefit assessment were attributed to be able to attest pre-blasting weakening effects practically.Meanwhile crack propagation analysis after pre-blasting weakening showed that in all triple monitoring bore holes rock masses of top-coal would be fallen into three stages from the bottom up:fracture zone,plastic zone and elastic zone generally,and fracture toughness respectively in correspondent zones was calculated by the analytical formula:0.5616–0.8806,0.6403–0.9541 and0.7535–1.1900 MPa m1/2after pre-blasting weakening.Pressure monitoring prediction and economical benefit assessment also indicated that it was necessary to introduce the pre-blasting weakening with predominant blasting scheme from both views.For excavation in extremely steep and thick coal seams,relevant results would be a useful tool to study the mechanism of pre-blasting weakening both qualitatively and quantitatively.

Incompressible Flow and Heat Transfer over a Plate: A Hybrid Integral Domain-Discretized Numerical Procedure

This work deals with incompressible two-dimensional viscous flow over a semi-infinite plate ac-cording to the approximations resulting from Prandtl boundary layer theory. The governing non-linear coupled partial differential equations describing laminar flow are converted to a self-simi- lar type third order ordinary differential equation known as the Falkner-Skan equation. For the purposes of a numerical solution, the Falkner-Skan equation is converted to a system of first order ordinary differential equations. These are numerically addressed by the conventional shooting and bisection methods coupled with the Runge-Kutta technique. However the accompanying energy equation lends itself to a hybrid numerical finite element-boundary integral application. An appropriate complementary differential equation as well as the Green second identity paves the way for the integral representation of the energy equation. This is followed by a finite element-type discretization of the problem domain. Based on the quality of the results obtained herein, a strong case is made for a hybrid numerical scheme as a useful approach for the numerical resolution of boundary layer flows and species transport. Thanks to the sparsity of the resulting coefficient matrix, the solution profiles not only agree with those of similar problems in literature but also are in consonance with the physics they represent.

A Hybrid ARQ System with Erasures Correction and Parity Retransmission

A modified type of Hybrid ARQ system with erasures correction and parity bits retransmission is considered. Performance of the system is analyzed under assumption that the forward channel suffers from Nakagami common fading and additive white Gaussian noise. A good agreement between theoretical results and simulation is achieved. The proposed ARQ protocol is compared with other known Hybrid ARQ algorithms. It demonstrates significantly higher throughput efficiency in a range of SNR.

A hybrid-stress element based on Hamilton principle

A novel hybrid-stress finite element method is proposed for constructing simple 4-node quadrilateral plane elements, and the new element is denoted as HH4-3fl here. Firstly, the theoretical basis of the traditional hybrid-stress elements, i.e., the Hellinger-Reissner variational principle, is replaced by the Hamilton variational principle, in which the number of the stress variables is reduced from 3 to 2. Secondly, three stress parameters and corresponding trial functions are introduced into the system equations. Thirdly, the displacement fields of the conventional bilinear isoparametric element are employed in the new models. Finally, from the stationary condition, the stress parameters can be expressed in terms of the displacement parameters, and thus the new element stiffness matrices can be obtained. Since the required number of stress variables in the Hamilton variational principle is less than that in the Hellinger-Reissner variational principle, and no additional incompatible displacement modes are considered, the new hybrid-stress element is simpler than the traditional ones. Furthermore, in order to improve the accuracy of the stress solutions, two enhanced post-processing schemes are also proposed for element HH4-3β. Numerical examples show that the proposed model exhibits great improvements in both displacement and stress solutions, implying that the proposed technique is an effective way for developing simple finite element models with high performance.