Finite axiomatization for symbolic probabilistic π-calculus

This paper focuses on the problem of seeking complete axiomatization for finite processes in the process calculus called symbolic probabilistic π-calculus introduced by Wu, Palamidessi and Lin. We provide inference systems for both strong and weak symbolic probabilistic bisimulations and also prove their soundness and completeness. This is the first work, to our knowledge, that provides complete axiomatization for symbolic probabilistic bisimulations in the presence of both nondeterministic and probabilistic choice.     

A Theory of Secure Mobile Computation with Confined Movement and Communication

An extended π calculus was introduced to deal with secure movement and intercommunication between agents. The system extends Nomadic-π with objective migration primitive and confined region which serves as annotation labels of agents and channels. The confined region labels were used to uniquely identify the constraints on the migration and communication of agents, with the labels, the agents could be confined in a secure subsystem and the inter-agent communication could be confined between agents located on trusted sites during computation. The operational semantics for the calculus was given out, and a type system which enforces security properties called confined migration and confined communication was developed.     

Recycling of aluminum from fibre metal laminates

Recycling of aluminum alloy scrap obtained from delaminated fibre metal laminates (FMLs) was studied through high temperature refining in the presence of a salt flux. The aluminum alloy scrap contains approximately mass fraction w(Cu) = 4.4%, w(Mg) = 1.1% and w(Mn) = 0.6% (2024 aluminum alloy). The main objective of this research is to obtain a high metal yield, while maintaining its original alloy compositions. The work focuses on the metal yield and quality of recycled Al alloy under different refining conditions. The NaCl-KCl salt system was selected as the major components of flux in the Al alloy recycling. Two different flux compositions were employed at NaCl to KCl mass ratios of 44:56 and 70:30 respectively, based on either the eutectic composition, or the European preference. Different additives were introduced into the NaCl-KCl system to study the effect of flux component on recycling result. Although burning and oxidation loss of the alloying elements during re-melting and refining take place as the drawbacks of conventional refining process, the problems can be solved to a large extent by using an appropriate salt flux. Experimental results indicate that Mg in the alloy gets lost when adding cryolite in the NaCl-KCl salt system, though the metal yield can reach as high as 98%. However, by adding w(MgF₂) = 5% into the NaCl-KCl salt system (instead of using cryolite) all alloying elements were well controlled to its original composition with a metal yield of almost 98%.     

Grain refining mechanism of carbon inoculation on Mg-Al alloy

The processing parameters and refining mechanism of Mg-Al alloy treated with a newly developed carbon inoculant under different conditions were investigated experimentally in this work. Results show that the finest ??-Mg grain in AZ91D alloy can be obtained after processing at about 740°C, and the average grain size of ??-Mg grain decreases from about 180.4 to 85.6 ??m by adding mass fraction w _in = 1% inoculant into melt. However, no evident refinement was achieved with excessive inoculant for Mn-free Mg-9Al alloy. Scanning electron microscope (SEM) photo, energy dispersive spectroscopy (EDS) analysis on the Mn-contained intermediate phase and differential scanning calorimetry (DSC) results indicate that Mn element plays an important role in the heterogeneous nucleation of ??-Mg grain. In the early stage of solidification, Al-Mn-C compound particles formed on the surface of Al₄C₃ nano-particles should be the potential nuclei for primary ??-Mg and probably responsible for the grain refinement achieved in the carbon inoculation process.     

基于SHEPWM的多模式调制切换算法

为了抑制切换过程电流和转矩冲击，提出了一种基于特定次谐波消除脉宽调制（SHEPWM）的多模式调制平滑切换算法. 根据SHEPWM算法的基本原理分析了相电压波形谐波分布情况；基于异步电机等效电路模型得到不同开关角个数下各次电流谐波幅值和调制度的关系；将切换过程抽象为电流基波及各次谐波的一阶暂态响应过程，建立了切换过程的数学模型，从电路原理的角度分析了切换冲击的产生机理；基于RT-LAB半实物实验平台对两种切换算法进行了硬件在环半实物试验对比. 研究结果表明:谐波幅值突变是造成转矩冲击的原因，在相电压基波相位π/2和3π/2处切换谐波电流幅值不发生变化，相电流可以平滑过渡；三相无法同时满足相位为π/2或3π/2的条件，因此分别在相电压基波相位π/2和3π/2处切换，切换过程电流和转矩冲击得到有效抑制.      

Antibacterial analyse of perovskite

We mainly studied the antibacterial properties of perovskite. Its structure was evaluated by X-ray diffractometer (XRD), scanning electron microscope (SEM), and ultraviolet-visible (UV-vis) absorption spectrometer etc. The antibacterial properties of perovskite to Candida albicans (ATCC10231), Escherichia coli (ATCC25922) and Staphylococcus aureus (ATCC6538) were investigated by the flask oscillation method. The results show that the perovskite has strong antibacterial ability, and continued antibacterial properties; its sterilization rates are 87.00%, 99.50%, 96.22% respectively to these three bacteria.     

External equality and absolute equality coincide in finite CCS and <Emphasis Type="Italic">π</Emphasis> calculus without summation

External equality and absolute equality are defined model independently by Fu. It is interesting and important to know whether these two equalities coincide or not. There are some results in Fu’s paper for this issue. It is relatively easy to prove the coincidence if the summation operator is in the language, otherwise it is harder. In fact Fu proposed it as an open problem whether the two equalities coincide in some languages without summation. In this paper, the proofs of the coincidence in finite CCS and π calculus without summation are given.     

Effectiveness of different orthoses on joint moments in patients with early knee osteoarthritis: Lateral wedge versus valgus knee bracing

The purpose of the study was to test the biomechanical differences between a lateral wedge and a valgus knee bracing on the knee joint moment during walking in patients with early stage of medial compartment knee osteoarthritis (OA). We conducted a crossover randomized design to compare gait parameters of 32 patients (with early stage medial compartment knee OA) in three different conditions during walking: with a custom-made lateral wedge of 5° (in standard shoes), with a valgus knee bracing (in standard shoes), and with control condition (in standard shoes). Both two-orthose conditions showed decreased loading patterns (knee adduction moment and knee adduction angular impulse) on the knee joint in dynamic condition (statistic probability P < 0.05). The decreased loading on OA knee in wedge condition was associated with a laterally shifted location of centre of pressure and increased ankle valgus degree and moment at the same foot (P < 0.05). It was not found significant differences in loading of the knee between these two-orthose conditions. These results indicated that, under dynamic condition, patients wearing lateral wedge and valgus knee bracing showed changes of moments on knee joints. Lateral wedge was as effective as valgus knee bracing in the treatment of early stage of knee OA.     

Calculation of 3D sensitivity matrix for electromagnetic tomography system using boundary elements and the perturbative approach

Electromagnetic tomography （EMT） is a non-invasive imaging technique capable of mapping the conductivity and permeability of an object. In EMT, eddy currents are induced in the object by the activation coils, and the receiving coils can measure the EMT voltages. When the activation frequency is significantly large, we can treat the metallic targets as electrically perfect conductors （EPCs）. In this situation, a thin skin approximation is reasonable and this type of scattering problem can be effectively treated by the boundary element method （BEM） formulated through integration equations. In this study, we compute three-dimensional （3D） sensitivity matrix between the sensors due to an EPC perturbation. Efficiency improvement is achieved through the utility of scalar magnetic potential. Two EPC objects, one sphere and one cube shaped, are simulated. The results agree well with the H dot H formula. Overall, we conclude that BEM can be used to calculate the 3D sensitivity matrix of an EMT system efficiently. This method is a general one for any shaped objects while the H dot H solution is only capable of producing the response for a small ball.     

Combustion optimization model for NO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> reduction with an improved particle swarm optimization

Abstract: This paper focuses on the combustion optimization to cut down NO _x emission with a new strategy. Firstly, orthogonal experimental design (OED) and chaotic sequences are introduced to improve the performance of particle swarm optimization (PSO). Then, a predicting model for NO _x emission is established on support vector machine (SVM) whose parameters are optimized by the improved PSO. Afterwards, a new optimization model considering coal quantity and air quantity along with the traditional optimization variables is established. At last, the operating parameters are optimized by the improved PSO to cut down the NO _x emission. An application on 600MW unit shows that the new optimization model can cut down NO _x emission effectively and maintain the load balance well. The NO _x emission optimized by the improved PSO is lowest among some state-of-the-art intelligent algorithms. This study can provide important guides for the low NO _x combustion in the power plant.     

Study on Oxidation Activity of CuCeZrO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> Doped with K for Diesel Engine Particles in NO/O<Subscript>2</Subscript>

CuCeZrO_x and KCuCeZrO_x catalysts were synthesized and coated on the blank diesel particulate filter (DPF) substrate and a particulate matter (PM) loading apparatus was used for soot loading. The catalytic performances of soot oxidation were evaluated by temperature programmed combustion (TPC) test and characterization tests were conducted to investigate the physicochemical properties of the catalysts. The reaction mechanism in the oxidation process was analyzed with diffuse reflectance infrared Fourier transform spectroscopy. The results demonstrated that CuCeZrO_x catalyst exhibited high activities of soot oxidation at low temperature and the best results have been attained with Cu_0.9Ce_0.05Zr_0.05O_x over which the maximum soot oxidation rate decreased to 410 °C. Characterization tests have shown that catalysts containing 90% Cu have uniformly distributed grains and small particle sizes, which provide excellent oxidation activity by providing more active sites and forming a good bond between the catalyst and the soot. The low-temperature oxidation activity of soot could be further optimized due to the excellent elevated NO’s conversion rate by partially substituting Cu with K. The maximum particle oxidation rate can be easily realized at such a low temperature as 347°C.     

Time-series forecasting using autoregression enhanced k-nearest neighbors method

This study proposes two metrics using the nearest neighbors method to improve the accuracy of time-series forecasting. These two metrics can be treated as a hybrid forecasting approach to combine linear and non-linear forecasting techniques. One metric redefines the distance in k-nearest neighbors based on the coefficients of autoregression (AR) in time series. Meanwhile, an improvement to Kulesh’s adaptive metrics in the nearest neighbors is also presented. To evaluate the performance of the two proposed metrics, three types of time-series data, namely deterministic synthetic data, chaotic time-series data and real time-series data, are predicted. Experimental results show the superiority of the proposed AR-enhanced k-nearest neighbors methods to the traditional k-nearest neighbors metric and Kulesh’s adaptive metrics.     

Safety Evaluation for Freeway Exit Ramp Based on Speed Consistency

Speed differential has direct relationship with road safety. Conventional speed consistency measures draw sample data from independent population that follows a normal distribution. These methods may fall into ecological fallacy and overestimate the safety level of road elements. After deducing the relationship between the difference in operating speed ΔV₈₅ and85(ΔV), the 85^th percentile value of individual speed reduction, this paper recommends 85(ΔV) and speed reduction rate 85(ΔV)R is used to evaluate ramp safety. Point speeds of individual vehicle at freeway diverge area, upper ramp, and lower ramp are collected by radar guns. Safety performance of 37 exit ramps are appraised using three different measures, namely, ΔV₈₅, 85(ΔV), and 85(ΔV)R. The results show that 85(ΔV) is 1.42 to 2.02 times of ΔV₈₅, and that the evaluation result of 85(ΔV)R is between the other two. The measure 85(ΔV)R considers not only individual speed but also the base speed on upstream element, which avoid the pitfalls of ecological fallacy and overestimation possessed by conventional measures. It is a safer and reasonable measure that should be adopted in practice.     

Research on Nonlinear Dynamic Simulation and Fatigue Reliability Life Prediction for Synthesis Transmission System of Self-Propelled Gun

Aiming to the puzzle that the inner load of nonlinear synthesis transmission system is difficult to obtain, a new kind of virtual prototype establishment and simulation method is put forward. The influence on nonlinear vibration with flexible rotor, bearing backlash is analyzed based on a virtual prototype. To validate the virtual prototype of nonlinear gear transmission system, the corresponding test platform is established. The consistency between simulation results and test results proves that the simulation results of the virtual prototype can be used to calculate the fatigue reliability life of key components. A new kind of fatigue reliability life prediction method of gear system considering multi-random parameter distribution is put forward based on the fatiguestatistic theory. Considering the periodicity of gear meshing, linear interpolation method is adopted to obtain the stress-time course of random load spectrum based on the gear’s complicated torque provided by virtual prototype. The gear’s P-S_a-S_m-N curved cluster can be simulated based on material’s P-S-N curve. The simulation process considers the parameter distributions of stress concentration coefficients, dimension coefficients and surface quality treatment coefficients, and settles the puzzle that traditional test methods cannot acquire the gear’s fatigue life of all reliability levels. This method can provide the distribution function and the interval of fatigue reliability life of gear’s danger region, and has a guide meaning for the gear maintenance periods determination and reliability evaluation.     

Genome-wide profiling identifies Saccharomyces cerevisiae response in PKC-SLT2 signaling and glycogen metabolic pathways to antifungal compound calcofluor white

Fungal infection remains a major problem worldwide, yet treatment options are limited owing to the lack of effective drugs, the significant toxicity of available compounds, and the emergence of drug resistance. The low toxicity of calcofluor white （CFW） is an attractive antifungal compound for its known inhibitive effects on trichophyton rubrum and candida albicans growth. However, the efficacy of CFW is limited in most cases. In order to search for effective means to improve its efficacy, using saccharomyces cerevisiae as a model, we have used microarrays to examine the cell＇s response when treated with CFW on the genome scale. We found that both the PKC-SLT2 （i.e, protein kinase C-mitogen activated protein kinase） and the glycogen metabolic pathways are activated upon CFW treatment. These results suggest that the key components in these pathways could be targeted by other drugs to counter the cell＇s compensative response, thus to further substantiate the inhibitive effect of CFW on fungal growth, which may lead to treatment regimens with improved efficacy of this compound in clinical applications.     

高胆固醇饮食对胆囊结石形成和胆囊运动的影响

目的探讨高胆固醇饮食(HCD)能否引起胆囊胆固醇结石和对胆囊运动的影响及其机制。方法用实体解剖、B超观察HCD组、正常对照组的胆囊成石情况;测定两组的胆囊运动功能;用放免法测定空腹及脂肪餐后血浆胆囊收缩素(CCK)水平;用比色法测定胆汁中胆固醇浓度;观察胆囊病理学改变。结果HCD组的胆固醇结石成石率、胆汁胆固醇浓度显著高于正常对照组(P<0.05);HCD组的脂肪餐后CCK水平、胆囊排空功能低于正常对照组(P<0.05);HCD组有9例出现胆囊炎症性病理改变;正常对照组仅1例出现黏膜水肿。结论高胆固醇饮食可以造成家兔的胆囊胆固醇结石,成石的原因可能与胆囊运动功能障碍、胆固醇代谢紊乱、血浆CCK水平降低、胆囊炎症以及它们之间的相互作用有关。     

Lattice-based group signature with verifier-local revocation

Among several post quantum primitives proposed in the past few decades, lattice-based cryptography is considered as the most promising one, due to its underlying rich combinatorial structure, and the worst-case to average-case reductions. The first lattice-based group signature scheme with verifier-local revocation(VLR) is treated as the first quantum-resistant scheme supported member revocation, and was put forward by Langlois et al. This VLR group signature(VLR-GS) has group public key size of O(nm log N log q), and a signature size of O(tm log N log q log β). Nguyen et al. constructed a simple efficient group signature from lattice, with significant advantages in bit-size of both the group public key and the signature. Based on their work, we present a VLR-GS scheme with group public key size of O(nm log q) and signature size of O(tm log q). Our group signature has notable advantages: support of membership revocation, and short in both the public key size and the signature size.     

用因素分析理论分析铁路运营指标 对铁路货运收入的影响

论文分析了货物周转量、发送量、装车数、平均运程及货车静载重等铁路运营指标与铁 路货运收入的关系,运用微积分方法推导出了指标因素影响分析的计算公式,得出了分析铁路 运营指标对铁路货运收入影响的计算方法,并给出了计算实例.     

Dry milling of the ultra-high-strength steel 30CrMnSiNi2A with coated carbide inserts

The ultra-high-strength steel (UHSS) plays an important role in the mechanical industry because of their special performances. The machinability of 30CrMnSiNi2A steel was studied in dry milling with two different coated tools in the present work. This paper introduced that 30CrMnSiNi2A steel was a kind of difficult-to-machine materials. The results showed that the cutting force components of feed direction and cutting width direction, i.e. F x and F y , increased slightly with increasing the cutting speed and feed rate. The values of axial force component F z were much larger than F x and F y , and increased obviously with increasing the milling speed. The workpiece surface had the minimum roughness at the cutting speed of 150 m/min. The physical vapor deposition (PVD) coated ((Ti, Al)N-TiN) insert was more suitable for machining 30CrMnSiNi2A steel than the chemical vapor deposition (CVD) coated (Ti(C, N)-Al 2 O 3 ) insert. Moreover, the main failure modes of PVD-coated insert were micro-chipping and coating spalling. The wear modes of CVD-coated insert were ploughing, coating spalling, and cratering. The serious adhesive wear and the abrasion with some adhesion were the main wear mechanism of PVD- and CVD-coated inserts, respectively.     

Explore the possibility of forming fcc high entropy alloys in equal-atomic systems CoFeMnNiM and CoFeMnNiSmM

The multi-principal high-entropy alloys (HEAs) are promising new alloys. However, it is a challenge to screen out the suitable composition from the diverse combinations. Referring to the prototype AuCu₃ with AB₃-L1₂ structure, where it becomes a face-centered cubic (fcc) structure if element A and B are the same element, the site occupying tendencies of the elements and thermodynamic functions are predicted by using the sublattice model supported with first-principles total energy calculations. By considering the Gibbs energy of formation and the configurational entropy, the fcc HEAs in available literatures are examined, and the results of the quinary system with equal-atomic composition CoFeMnNiM and the hexbasic system with equal-atomic composition CoFeMnNiSmM are reported, respectively, where the element M is selected from the rest of the periodical table. When M=Cr, Zn, Ru, Rh, Pd, Re, Os, Ir, or Pt in the quinary systems CoFeMnNiM and when M=Ru, Pd, or Pt in the hexbasic systems CoFeMnNiSmM, respectively, the alloys are recommended to be potential fcc HEAs. The new approach opens a new way to mine the rich ores of HEAs.