Effect of mechanical degradation of laminated elastomeric bearings and shear keys upon seismic behaviors of small-to-medium-span highway bridges in transverse direction

Laminated elastomeric bearings have been widely used for small-to-medium-span highway bridges in China, in which concrete shear keys are set transversely to prohibit large girder displacement. To evaluate bridge seismic responses more accurately, proper analytical models of bearings and shear keys should be developed. Based on a series of cyclic loading experiments and analyses, rational analytical models of laminated elastomeric bearings and shear keys, which can consider mechanical degradation, were developed. The effect of the mechanical degradation was investigated by examining the seismic response of a small-to-medium-span bridge in the transverse direction under a wide range of peak ground accelerations（PGA）. The damage mechanism for small-to-medium-span highway bridges was determined, which can explain the seismic damage investigation during earthquakes in recent years. The experimental results show that the mechanical properties of laminated elastomeric bearings will degrade due to friction sliding, but the degree of decrease is dependent upon the influencing parameters. It can be concluded that the mechanical degradation of laminated elastomeric bearings and shear keys play an important role in the seismic response of bridges. The degradation of mechanical properties of laminated elastomeric bearings and shear keys should be included to evaluate more precise bridge seismic performance.

The mechanical response of multi-tower continuous-span suspension bridge deck pavement based on whole bridge analysis

The effect of multiple span suspension structure on the mechanical response of bridge deck pavement was studied, and finite element analysis (FEM) of stress and strain of pavement according to the bridge floor system features of super-long and high flexibility was made. Meanwhile, the FEM results were compared with those of the single span suspension structure. Three-stage analytic hierarchy process (AHP) is developed to analyze the mechanical response including whole bridge analysis, partial beams section analysis and orthotropic plate analysis. The most unfavorable load position was determined by the numerical solutions acquired from each stage to study the main mechanical index of multiple span suspension structure. The FEM results showed that the mechanical response numerical solutions by using the three-stage AHP are greater than those by simplified boundary condition, and the force condition of multiple span suspension structure is worse than that of the single span suspension structure.

Cryptographic obfuscation for smart contracts: Trustless bitcoin bridge and more

Privacy protection for smart contracts is currently inadequate.Existing solutions for privacy-preserving smart contracts either support only a limited class of smart contracts or rely on noncryptographic assumptions.We propose a cryptographic obfuscation scheme for smart contracts based on existing blockchain mechanisms,standard cryptographic assumptions,and witness encryption.In the proposed scheme,an obfuscated smart contract does not reveal its algorithm and hardcoded secrets and preserves encrypted states.Any user can provide it with encrypted inputs and allow an untrusted third party to execute it.Although multiparty computation(MPC)among dynamically changing users is necessary,its privacy is protected if at least one user is honest.If the MPC does not finish within a period of time,anyone can cancel and restart it.The proposed scheme also supports decentralized obfuscation where even the participants of the obfuscation process cannot learn secrets in the obfuscated smart contract unless all of them are malicious.As its applications,we present a new trustless bitcoin bridge mechanism that exposes no secret key and privacy-preserving anti-money laundering built into smart contracts.

Structural Design and Control Strategy Analysis of Micro/Nano Transmission Platform

A fully flexure micro/nano transmission platform(MNTP)which has five degrees of freedom is designed on the basis of bridge type amplification mechanism.According to the kinematic theory and the elastic beam theory,the theoretical output displacement equation of the platform is derived,and then piezoelectric actuator(PZT)is calibrated.Meanwhile,a full closed-loop control strategy of the platform is established using the feedforward proportional-integral-derivative(PID)compound control algorithm based on the Preisach model.Moreover,the total transfer function of the micro positioning system is derived,and the calculation method of output signal is acquired.Finally,the theoretical output displacement is verified by finite element analysis(FEA)and positioning experiments.

CMC International Advertising & Exhibition Co.Ltd.-Bridging the Sino-foreign Mechanical and Electrical Trade

CMC International Advertising & Exhibition Co. Ltd.(CMC-IAE) is a specialized subsidiary of China National Machinery Import & Export Corporation (CMC) with corporate status. In the past 47 years, the company has played a positive role in the conveyance of information and development of China’s mechanical and electrical trade with other countries in the forms of specialized advertising and exhibitions, contributing greatly to the bridging of Sino-foreign mechanical and electrical trade and expansion of international economic and trade exchanges. CMC-IAE deals mainly in and acts as agent for the advertising business of both Chinese and foreign enterprises, and trading companies. It sponsors large-scale exhibitions and promotional activities both at home and abroad; undertaking to design and produce various advertisements,pamphlets and printing matters; engaging in