一类SP结构的不可能差分区分器证明

针对分组密码SP结构的不可能差分区分器轮数的下界进行证明,提出的方法使用线性代数的理论,对系数矩阵P及P-1进行分析,提出了系数矩阵部分子空间存在两个行向量线性相关时,可证明至少存在四轮不可能差分区分器。uBlock算法是SPN结构,提出的方法对uBlock算法进行了分析验证,说明了结论的正确性,进一步,使用该算法搜索到比uBlock算法设计文档更多的不可能差分区分器。针对SPN结构线性扩散层P,使用了本原指数的概念,使用线性扩散层P的本原指数对SPN结构不可能差分的轮数进行论证。分析结果表明,分组密码SP结构至少存在四轮不可能差分区分器。     

An Adaptive Fault-tolerant Control Method for Robot Manipulators

International Journal of Control, Automation and Systems - This paper presents a new method for adaptive continuous nonsingular fast terminal sliding mode control (ACNFTSMC) based on a novel...     

Flocking of Multi-agent Systems with Unknown Nonlinear Dynamics and Heterogeneous Virtual Leader

This paper investigates the flocking control of multi-agent systems with unknown nonlinear dynamics while the virtual leader information is heterogeneous. The uncertain nonlinearity in the virtual leader information is considered, and the weaker constraint on the velocity information measurements is assumed. In addition, a bounded assumption on the unknown nonlinear dynamics is also considered. It is weaker than the Lipschitz condition adopted in the most flocking control methods. To avoid fragmentation, we construct a new potential function based on the penalty idea when the initial network is disconnected. A dynamical control law including a adjust parameter is designed to achieve the stable flocking. It is proven that the velocities of all agents approach to consensus and no collision happens between the mobile agents. Finally, several simulations verify the effectiveness of the new design, and indicate that the proposed method has high convergence and the broader applicability in practical applications with more stringent restrictions.

     

Semi-global Adaptive Bipartite Output Consensus of Multi-agent Systems Subject to Input Saturation and External Disturbance Under Switching Network

This paper investigates semi-global adaptive bipartite output consensus of continuous-time multi-agent systems (MASs) with input saturation and non-identical external disturbance under jointly connected switching network. An adaptive bipartite output consensus protocol of MASs is proposed by using low-gain feedback technology. It is turned out that semi-global adaptive bipartite consensus of MASs can be achieved under the protocol. Furthermore, the proposed control protocol can be applied for MASs under fixed network, and semi-global adaptive bipartite output consensus can be also achieved in this case. Finally, the simulations will verify the effectiveness of theoretical results.

     

CMADS驱动SWAT模型在水循环模拟中的应用——以洱海流域为例

基于大气数据驱动水文模型的输出结果开展水循环模拟研究是大气和水文学界的研究热点。利用中国大气同化驱动数据集CMADS驱动SWAT模型,模拟2009～2016年期间洱海流域关键水循环要素的时空分布特征。结果表明:①CMADS数据集可很好地驱动SWAT模型,在洱海流域适用性较好,可用于水循环模拟研究。②从时间上看,洱海流域年降水量、实际蒸散和年产水量均呈现出先减少后增加的趋势,分别以4.6,29.3,15.0 mm/a的速率递增,多年平均降水量、多年平均实际蒸散发和多年平均产水量分别为792.8,565.5,286.1 mm。从空间上看,洱海西部降水最丰沛,东部地区次之,北部地区最低;实际蒸散发空间差异性相对较小,高值区主要分布于洱海湖区周围;产水量空间分布差异性较大,洱海西部产水量最大,其次为洱海北部和东部山区。③湿润度呈现出增加的趋势,而产水系数表现出减少的趋势,多年平均湿润度和产水系数分别为0.61和0.43;实际蒸散发与降水变化趋势一致,但与潜在蒸散发变化趋势相反,表明水分条件是限制洱海流域潜热的主要因子。     

A new way of strengthening and toughening for carbon fiber reinforced polyphenylene sulfide (CF/PPS) composites via matrix modification

The effect of pressure-induced flow(PIF) processing on the mechanical properties of noncontinuous carbon fiber(CF) reinforced polyphenylene sulfide(PPS) composites was investigated. A series of CF/PPS composites under different processing conditions were prepared through PIF-processing. SEM observations showed that the interfaces adhesion between CFs and PPS became stronger and ductile fracture mainly occurred in PPS matrix. This brought to a great increase of both strength and toughness by about 2 folds, when the composites were processed at 240 ℃ and under 263 MPa. The results in differential scanning calorimetry(DSC) and X-ray diffraction(XRD) measurements indicated more regular crystalline structures and orientation of lamellae formed during PIF-processing.     

冲角对车轮与道岔尖轨弹塑性接触的影响

在机车运行中轮轨间存在冲角,改变轮轨接触关系.针对冲角对车轮与尖轨接触的影响问题,建立了车轮—尖轨接触三维有限元模型,通过弹塑性接触计算,分析不同冲角工况下的接触情况.结果表明:轮轨间冲角的存在,导致车轮与钢轨接触位置发生改变,基本轨和尖轨接触斑中心不在同一钢轨横断面上,冲角越大,超前或滞后的数值越大;车轮与尖轨接触法向力随冲角的增大而增大;不同冲角工况下车轮与尖轨的接触等效应力变化规律基本一致,最大等效应力均出现在2 m位置处;冲角的增大会造成尖轨前端等效应力增大,导致车轮轮缘与尖轨的磨耗增加,降低车轮和尖轨的使用寿命.     

Method Based on Time Randomization to Resist Fault Sensitivity Analysis

A fault sensitivity analysis (FSA)-resistance model based on time randomization is proposed. The randomization unit is composed of two parts, namely the configurable register array (R-A) and the decoder (chiefly random number generator, RNG). In this way, registers chosen can be either valid or invalid depending on the configuration information generated by the decoder. Thus, the fault sensitivity information can be confusing. Meanwhile, based on this model, a defensive scheme is designed to resist both fault sensitivity analysis (FSA) and differential power analysis (DPA). This scheme is verified with our experiments.     

混凝法去除水中TiO2纳米颗粒

为了探讨混凝法去除水中纳米颗粒的可行性及最佳条件,研究了无机混凝剂（PAC、PFS、PAFC）和有机絮凝剂（CPAM、APAM、NPAM）对TiO₂纳米颗粒的去除效果,并考察了投加量、pH、沉淀时间、水力条件及有机无机复配对TiO₂纳米颗粒去除效率的影响。单独投加PAC、PFS和PAFC时,三者对应的最高去除率分别为92.51%、84.43%、95.66%。单独投加CPAM、APAM、NPAM时三者对应的去除率仅为61.72%、29.06%、55.37%。复配最佳混凝条件为：投加40 mg/LPAC和3 mg/LCPAM,pH值为9,G值143.5/s,沉淀时间15 min,此时,TiO₂纳米颗粒去除率为99.6%。     

Investigation on the cleaning of KDP ultra-precision surface polished with micro water dissolution machining principle

A potassium dihydrogen phosphate (KDP) optical crystal was machined to an ultra-precision surface with water-in-oil (W/O) micro emulsion polishing fluid. The micro water dissolution principle utilized in the machining process is discussed, its planarization mechanism is illustrated, and an ultra-precision polished surface with 2.205 nm RMS roughness is obtained. However, a substantial quantity of residual contamination remained on the polished surface after machining. This can seriously impact the optical performance of the crystal, and so it must be removed. Fourier transform infrared (FTIR) spectroscopy was used to conduct an investigation into the composition of the surface residue, and the results showed that the residue was comprised of organic chemicals with hydrocarbon chains and aromatic ether, i.e., mostly the polishing fluid. The cleaning method and the principle on which the KDP ultra precision surface investigation is based are discussed in detail, and the cleaning experiments with selected KDP-compatible organic solvents were then performed. FTIR transmittance spectra measurement and microscopic observations were employed to assess the effects of the cleaning process on the surface of the KDP crystal. The results showed that toluene cleaning achieved the most desirable results. This cleaning method produced a surface roughness of 1.826 nm RMS, which allows the KDP crystal to be applied to subsequent engineering applications.