P2P网络环境下的一种高效搜索算法:Multilayer Light-Gossip

由于现有非结构化P2P网络路由协议均在应用层实现,缺乏缓存机制和对Internet底层通信子网路由资源的利用,存在可扩展性差和效率不高的问题·在基于层域结构的RLP2P网络环境下,将路由空间分为域间和域内两层,结合泛洪和生成树搜索方式的优点,提出并实现了一种Multilayer Light-Gossip分级搜索算法和域间基于正六边形的蜂窝路由探测策略,把网络中的搜索消息分为域间和域内扩散两类分级扩散,以一定的消息冗余保持网络的稳健性和搜索的有效性,使定位某种服务的工作量和查询范围从网络中的所有结点数降到域内的节点数·运用预测评估方法对级间路由消息进行预分组,使消息能够自适应地沿着一条在时间度量上距离尽量短的路径前进·实验结果表明,Multilayer Light-Gossip算法大幅提高搜索效率和减少冗余消息,在广域环境下具有良好的搜索性能和扩展性·

Geochemistry of Platinum Group Elements in Mafic-Ultramafic Rocks of Xinjie Intrusion

The platinum group elements (PGE) in the mafic ultramafic suite in the Xinjie layered intrusion and associated basalts and syenites were analyzed using neutron activation techniques after fire assay preconcentration. On this basis, the geochemistry of the platinum group during the magmatic stage is discussed. With respect to PGE distribution, the Xinjie layered intrusion is similar to the Bushveld ferruginous ultramafic series and is distinct from komatiite and Alpine type peridotite. It is also similar to the Emeishan basalt in PGE characteristics, implying that the original magmas of them may be of the same type.

Lie group analysis for thermophoretic and radiative augmentation of heat and mass transfer in a Brinkman-Darcy flow over a flat surface with heat generation

A boundary layer analysis is presented to investigate numerically the effects of radiation, thermophoresis and the dimensionless heat generation or absorption on hydromagnetic flow with heat and mass transfer over a flat surface in a porous medium. The boundary layer equations are transformed to non-linear ordinary differential equations using scaling group of transformations and they are solved numerically by using the fourth order Runge-Kutta method with shooting technique for some values of physical parameters. Comparisons with previously published work are performed and the results are found to be in very good agreement. Many results are obtained and a representative set is displayed graphically to illustrate the influence of the various parameters on the dimensionless velocity, temperature and concentration profiles as well as the local skin-friction coefficient, wall heat transfer, particle deposition rate and wall thermophoretic deposition velocity. The results show that the magnetic field induces acceleration of the flow, rather than deceleration （as in classical magnetohydrodynamics （MHD） boundary layer flow） but to reduce temperature and increase concentration of particles in boundary layer. Also, there is a strong dependency of the concentration in the boundary layer on both the Schmidt number and mass transfer parameter.

A problem solving framework for group decision support system

A new problem solving framework for group decision support system using layer model approach is proposed. This kind of framework includes four basic layers, namely, application layer, task layer, logical layer and physical layer. Based on indicating the respective meanings of those layers a task skeleton of group decision support system and a logical structure of group decision support system generator are put forward and discussed in detail. The framework provides theoretical guidance for developing group decision support system to lower systematic development complexity and support reuse of software.

TAILING WAVETRAIN GENERATION IN PRECURSOR SOLITON GENERATION IN TWO-LAYER FLOW

A theory of tailing wavetrain generation for the precursor soliton generation in two-layer flow is presented by using averaged KdV equations (AKdV), which are derived by the authors in terms of Whitham's method of averaging([1,2]). From the AKdV equations, group velocities of the tailing wavetrain generation are obtained by means of generating conditions of the tailing wavetrains, furthermore an analytical solution of the tailing wavetrain generation is found theoretically. A comparison between the theoretical and numerical results is carried out in the present paper, which shows that the theoretical results are in good agreement with the numerical ones, obtained from the fKdV equation in two-layer flow with the depth of unity in the rest.

New U-Pb and Sm-Nd Data and REE Distribution in Sulphides of Paleoproterozoic PGE Layered Intrusions in the Arctic Part of the Fennoscandian Shield

The U-Pb (on zircon) and Sm-Nd analysis is a popular isotope-geochronological tool for estimating the age of rocks from PGE mafic-ultramafic intrusions. Sulphides can be used to study the geochronology of ore processes as well, since they should indicate the time of ore mineralization. Gabbronorite has been sampled from the Passivaara reef at the Penikat layered intrusion (Finland) for U-Pb and Sm-Nd isotope single zircon analyses in order to separate sulphide minerals. The Sm-Nd isotope age of gabbronorite has been dated at 2426 ± 36 Ma;eNd(T) = −1.4 ± 0.4. The Sm-Nd isotope age on sulphides and rock-forming minerals reflects the crystallization time of the ore-bearing gabbronorite from the Passivaara reef of the Penikat layered intrusion. The mass-spectrometer analytical environment and modes of operation have been adjusted to detect REE in sulphide minerals on example of pyrite from the PGE Penikat layered intrusion (Finland) and chalcopyrite from the Talnakh deposit (Norilsk area, Russia) has been estimated. The total REE content in pyrite is ca. 3.5 ppm, which is enough to define the Sm-Nd age of pyrite. The study shows how to use the mineral/chondrite spectra to evaluate the accuracy of the REE analytical results on example of State Standard Sample 2463 (Russia).

SIMILARITY SOLUTIONS OF BOUNDARY LAYER EQUATIONS FOR A SPECIAL NON-NEWTONIAN FLUID IN A SPECIAL COORDINATE SYSTME

Two dimensional equations of steady motion for third order fluids are expressed in a special coordinate system generated by the potential flow corresponding to an inviscid fluid. For the inviscid flow around an arbitrary object, the streamlines are the phi-coordinates and velocity potential lines are psi-coordinates which form an orthogonal curvilinear set of coordinates. The outcome, boundary layer equations, is then shown to be independent of the body shape immersed into the flow. As a first approximation,assumption that second grade terms are negligible compared to viscous and third grade terms. Second grade terms spoil scaling transformation which is only transformation leading to similarity solutions for third grade fluid. By using Lie group methods,infinitesimal generators of boundary layer equations are calculated. The equations are transformed into an ordinary differential system. Numerical solutions of outcoming nonlinear differential equations are found by using combination of a Runge-Kutta algorithm and shooting technique.

A Layer-Cluster Key Agreement Protocol for Ad Hoc Networks

Mobile ad hoc networks create additional challenges for implementing the group key establishment due to resource constraints on nodes and dynamic changes on topology. The nodes in mobile ad hoc networks are usually low power devices that run on battery power. As a result, the costs of the node resources should be minimized when constructing a group key agreement protocol so that the battery life could be prolonged. To achieve this goal, in this paper we propose a security efficient group key agreement protocol based on Burmester-Desmedt （BD） scheme and layer-cluster group model, referred to as LCKM-BD, which is appropriate for large mobile ad hoe networks. In the layer-cluster group model, BD scheme is employed to establish group key, which can not only meet security demands of mobile ad hoc networks but also improve executing performance. Finally, the proposed protocol LCKM-BD are compared with BD, TGDH （tree-based group Diffe-Hellman）, and GDH （group Diffie-Hellman） group key agreement protocols. The analysis results show that our protocol can significantly decrease both the computational overhead and communication costs with respect to these comparable protocols.

姬塬地区长8油层组储层特征分析

为确定长8油层储层现今表征,储层物性受黏土矿物胶结物控制模式,储层沉积作用和沉积后期所经历的成岩变化,通过铸体薄片、扫描电镜等方法研究了储层基本特征和成岩作用及沉积作用,在整体低渗的背景下,部分位于相对渗透率较高区域的油井有较高的产量,理清研究区长8储层富集规律,对地区内岩石孔隙度下降因素进行剖析。结果表明,姬塬地区有利储层多发育水下分流河道和河口坝沉积,特别是砂体中心部位储层物性是最好,可见长8油层组的储集性能和渗流性能好,即粒间孔型、粒间孔+溶孔型和溶孔+粒间孔型。溶孔型、粒间孔+微孔型两种孔隙组合类型的渗流性能较差。微孔型和溶孔+微孔型两种孔隙组合类型的储集空间主要由半径极小的微孔构成,连通性较差,其孔隙内表面积和渗流阻力,储集性能和渗流性能较差。

基于DEM-MBD的油茶林分层切抛式开沟刀组研制

针对油茶种植林地土壤粘重板结环境下因刀片剧烈冲击导致开沟效果不理想、功率消耗较大和机具振动的问题,该研究设计了一种油茶林分层切抛式开沟刀组。根据油茶开沟施肥的农艺要求,分析土壤与切土刀片间的相互作用、建立土壤颗粒在抛土刀面上的动力学微分方程,得到影响刀组切抛性能的关键因素为偏心系数、最大工作半径r1处滑切角、安装角和刀轴转速。通过EDEM-RecurDyn耦合仿真,以作业功耗与沟深稳定性系数为评价指标进行单因素及二次正交旋转组合试验,基于NSGA-Ⅲ算法对构建的二阶多项式响应面模型进行循环逼近优化,确定最优参数组合为:偏心系数1.3、最大工作半径r1处滑切角64.7°、安装角55.1°、刀轴转速301 r/min,与对照组单一外层切土刀和正装抛土刀的组合方式相比,最优参数组合下分层切抛式开沟刀组的扭矩波动降低率为21.53%。田间试验结果表明,最优参数刀组下仿真与田间试验的作业功耗、沟深稳定性系数相对误差分别为10.25%和4.55%,验证了耦合仿真模型的准确性;田间试验的作业功耗与沟深稳定性系数分别为25.96 kW和88.31%,比功耗和现有的果园开沟刀组相比降低了8.31%,沟深稳定性系数满足国家相关标准的技术要求,研究结果可为油茶林开沟刀组的设计和优化提供理论支撑与参考。

基于差异阈值循环分组的密钥生成算法

针对无线通信中通信双方提取的信道特征存在明显差异,导致双方的密钥生成速率和一致率较低的问题,提出差异阈值循环分组的密钥生成算法(TGKG)。首先,对信道状态信息(CSI)进行差异阈值分组,使任意组内元素间的间隔均大于该值,提高组内数据的差异,减小量化误差以降低密钥不一致率;循环分组只需一方进行,防止因数据误差导致的分组不一致。同时,提取信道系数的实部和虚部量化,增加量化比特数目,提高了密钥生成速率。通过概率论及信息论公式证明了所提算法在密钥不一致率、密钥可达速率和安全性3方面的优势。实验结果表明,所提算法在5 dB信噪比(SNR)条件下,通信双方的密钥不一致率约为2%,密钥生成速率约为142%。

一种薄互层条件下致密砂体展布地震综合预测的策略

松辽盆地北部上白垩统高台子油层发育典型的致密砂岩储层,属于三角洲前缘沉积环境,该套地层从上至下有三套主力砂层组,每套砂层组均为砂泥岩薄互层,单层砂岩厚度超薄,一般为2 m~3 m。寻找区域内砂体比高的砂层组并刻画砂组内部单砂体空间分布是致密油勘探开发的关键所在。而常规属性分析及地震反演储层预测效果差、精度低,为此提出了针对性的地震综合预测策略,除地震资料保真高分辨率处理和岩石物理分析外,主要包括砂层组级的多属性融合砂地比预测技术以及单砂体级的相控地质统计学反演技术。具体工作流程为:第一在地震属性归一化基础上,利用聚类分析方法将地震属性划分为三大类,每类挑选相关性最高的地震属性进行多元线性拟合,建立砂层组级的多属性融合砂地比预测模型;第二利用统计分析手段建立井点先验信息与砂地比对应关系,建立砂地比先验信息约束的单砂体级的相控地质统计学反演方法。松辽盆地北部某区块应用实例表明,综合预测策略在评价砂层组级的砂体发育情况、刻画砂层组内部薄砂体空间展布方面取得较好的效果,指导了水平井井组的部署方案优化设计。

Anisotropy Characteristics of Magnetostatic Surface Wave Propagating in YIG/Dielectric/Metal Layered Structure

The anisotropy of magnetostatic surface wave （MSSW） propagating in finite width YIG /dielectric/metal layered structure is analyzed. This problem is solved by finding the rigorous solution of each layer from Maxwell equation and the appropriate transmission Green＇s function matrix G. From the relationship of Green＇s function matrixes of dielectric layer and ferrite layer, the dispersion equation is obtained. The MSSW filter is designed to verify the dispersion characteristics. The experiment results are in good agreement with the calculating data from the model.

一种改进的群组机器人网络路由算法

针对群组机器人系统在应急场景下移动频繁、能量有限的特点,提出了一种基于能量与速度的分簇自组织按需距离矢量协议(Clustered Ad hoc On-Demand Distance Vector Protocol Based on Energy and Speed,ESC-AODV),以延长群组机器人网络运行时间,提高通信可靠性。用路由性能代替跳数作为路由判据,目的节点在重复接收到路由请求(Route Request,RREQ)数据包时,若路由性能更小,则回复路由应答(Routing Reply,RREP)数据包,以此选择更好的路由,引入分簇结构,通过簇头和网关组成的骨干网络减少广播洪泛次数。实验结果证明,节点数量多时,改进的ESC-AODV协议在延长网络生存时间的同时,平均端到端时延、数据包投递率、吞吐量和路由开销均优于AODV以及基于能量、负载和速度的AODV路由协议(AODV Routing Protocol Based on Energy,Load and Speed,ELS-AODV)。ESC-AODV协议能够节约网络能量,提高可靠性,获得更优的网络性能。

多工作面连续开采地表沉陷与强矿震联动响应规律

深部矿井多工作面大空间开采导致大能量强矿震事件频发,同时地表伴随剧烈的下沉变形,掌握具体地层条件下地表移动与强矿震时空分布响应规律对于深部矿井动力灾害防控意义重大。以兖州矿区东滩煤矿63_(上)04,63_(上)05,63_(上)06工作面为工程背景,基于关键层理论与复合破断原理,对东滩煤矿复杂地层进行了科学划分,现场实测了深井厚硬岩层下多工作面开采地表沉降规律及强矿震时空分布特征,分析了多工作面连续开采下关键层组运移演化规律,揭示了关键层组破断演化、地表沉陷规律与大能量强矿震分布的联动效应。研究结果表明:(1)东滩煤矿六采区地层可以划分出4个关键层组,每个关键层组包含一层关键层和若干坚硬岩层,相比单一关键层,关键层组发生复合破断时的矿震能量更高、破断步距更大,对上覆岩层的运移及地表下沉影响也更为突出。(2)地表沉陷观测结果显示,63_(上)04,63_(上)05工作面开采结束,地表下沉系数分别为0.189,0.458;63上06工作面当前已开采808.29 m,地表下沉系数为0.492,受多关键层组地质赋存特征影响,东滩煤矿六采区地表下沉系数远小于兖州矿区其他矿井平均地表下沉系数(0.75~0.85),地表未达到充分采动,下沉趋势为:无明显下沉–下沉空间显著–下沉空间逐渐增大。(3)矿震监测结果显示,63上04工作面开采时,大能量强矿震事件主要集中在低位关键层组Ⅰ,Ⅱ层位,随着多工作面连续开采,大能量强矿震逐渐向高位转移,逐渐集中至关键层组Ⅱ,Ⅲ层位。(4)由地表沉陷及大能量强矿震实测数据可知,东滩煤矿六采区多工作面连续开采下关键层组复合破断覆岩结构呈“断悬”结构–“铰接”结构交替上升,逐层演化过程验证了覆岩运动、地表沉陷及大能量强矿震3者之间存在一定的联动效应。研究成果可对类似工程地质条件下多关键层组复合破断研究及大能量强矿震预控提供一定参考。

煤层群上下保护层开采围岩应力及裂隙演化规律研究

为实现煤层群上下保护层开采过程中被保护层卸压瓦斯的高效抽采,采用数值模拟方法研究上下保护层开采后围岩应力、裂隙分布及演化规律,探明上下保护层开采的卸压瓦斯富集区。研究结果表明:下保护层开采后,被保护层工作面上侧覆岩卸压高度明显大于下侧覆岩卸压高度,次采上保护层后,增大了被保护层卸压范围。下保护层开采后被保护层走向卸压角为63°,倾斜上下边界卸压角为87°、72°。上保护层开采后被保护层走向卸压角为59°,倾斜上下边界卸压角为76°、79°。经过保护层卸压后,被保护层抽采卸压瓦斯纯流量相比卸压前呈现10余倍增大,卸压瓦斯抽采具有明显的时空效应。

非交互密钥协商综述

非交互密钥协商作为一种重要的密码学原语是一种极具潜力的安全信道建立范式,持续受到学术界和工业界的密切关注.本文综述了非交互密钥协商协议的发展概况以及待解决的问题.有别于以往的综述,我们在对传统的非交互密钥协商协议进行全面回顾的同时,还对由消息层安全协议衍生的一类部分非交互密钥协商协议进行了深入的探讨.这类协议的突出特点在于,它们能够(部分)非交互式地为群组建立(初次)会话密钥;且后续在群组需要动态变化时,仅需其中一个参与者发送一条请求消息,其他参与者进行监听就能完成群组会话密钥的更新.此外,本文首次讨论了一种基于非对称群密钥协商构造多方非交互密钥协商协议的潜在技术路线,以及利用区块链技术作为公钥基础设施扩充组件用于解决非交互密钥协商协议设计中潜在风险的方法.

平煤十三矿突出煤层群保护层选择论证

在突出矿井开采煤层群时,为了有效防治煤与瓦斯突出的风险,确保平煤十三矿己_(16-17)-14060工作面煤层群开采时的安全,必须采用开采保护层防治突出措施,选择合理可行的首采保护层。依据保护层选择和开采的基本原则,从己_(16-17)煤层、己_(15)煤层的矿井煤层赋存情况,煤与瓦斯突出危险程度,保护层开采效果,是否破坏被保护层开采条件和经济效益五个方面论述比较。结果表明,选择己_(16-17)煤层作为矿井首采保护层较合理,运用AHP法(层次分析法)构建了一个保护层选择模型,该模型进一步论证了将己_(16-17)煤层作为首选保护层开采的可行性和合理性,对平煤十三矿工作面的安全生产发挥了重要作用,为矿井的安全开采提供了可靠的依据。

AlLi-LDH中Al-O八面体环吸附锂的机制

采用共沉淀法合成铝锂层状双氢氧化物(AlLi-LDH)并进行提锂试验。AlLi-LDH的空间群为P32或C2/m,微观形貌呈直径为5~10μm的规则球形。AlLi-LDH吸附Li^(+)后,空间群转化为P32。当Li^(+)浓度为95.4 mg/L时,1 h后锂吸附量为8.98 mg/g;吸附48 h后,吸附量增加到16.50 mg/g;根据二级吸附模型预测Li^(+)吸附总量为17.57 mg/g。当Mg^(2+)/Li^(+)的质量比为1067时,Mg^(2+)/Li^(+)分离系数为29536。空间群为P32时,Li-O的相互作用强度变弱,且相互作用属于静电效应。具有P32空间基团的AlLi-LDH更容易吸附和解吸Li^(+)。

突出煤层群上保护层煤柱留设合理宽度研究

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