A Temporal-Rule Based Verification System for Business Collaboration Reliability

Based on the temporal rules defined for the business processe participating in a business collaboration, we present an implementation for a system called TiCoBTS to verify the reliability of the business collaboration

Discrete Element Modelling of Damage and Fracture of Brittle Materials

Concretes are widely used in civil engineering, such as bridges, roads, and water dams. However, damage occurs as the service age of the infrastructure increases. Investigations into the damage process can elucidate the fracture mechanisms and help to reduce the damage. Despite the fact that much research has been conducted on this topic, concrete fracture mechanisms remain unclear. Directly collecting microscale and/or meso-scale information (e.g., crack population, size, strength, and stress distribution) through laboratory experiments is challenging, However, this information is necessary for understanding the fracture process. Numerical simulation serves as a promising alternative as it can dynamically trace microcracking events and evaluate the spatial and temporal variations of stress in materials. Among the many numerical models, the discrete element method (DEM) is exceptionally successful in studying rocks and rock-like materials. Nevertheless, further improvements to DEM models are required to more accurately characterise materials' mechanical and fracture behaviours. To address the aforementioned problems, the present study developed superior discrete element models, including both homogeneous and heterogeneous models. The models were validated against finite element solutions and experiments, revealing that they can capture numerous behaviours of rock-like materials. The models were then used to study the mechanical and fracture behaviours of concretes under different loading conditions. The results indicate that the inhomogeneity of concrete strongly affects its fracture behaviours. Crack growth and stress distribution dynamically influence each other. Moreover, the crack population decreased exponentially with the crack length in the pre-peak stage. Crack proliferation usually initiated from the interior and grew outwards until the concrete disintegrated. The final disintegration of concrete usually resulted from the growth of several long-length cracks. The change in concrete strength was a consequence of the trade-off between strengthening aggregates and weakening ITZs. Furthermore, the introduction of vibration-assisted cutting mitigated crack growth in concretes and reduced spiking forces in the chipping process

Blockchain technology research and application: a systematic literature review and future trends

Blockchain, as the basis for cryptocurrencies, has received extensive attentions recently. Blockchain serves as an immutable distributed ledger technology which allows transactions to be carried out credibly in a decentralized environment. Blockchain-based applications are springing up, covering numerous fields including financial services, reputation system and Internet of Things (IoT), and so on. However, there are still many challenges of blockchain technology such as scalability, security and other issues waiting to be overcome. This article provides a comprehensive overview of blockchain technology and its applications. We begin with a summary of the development of blockchain, and then give an overview of the blockchain architecture and a systematic review of the research and application of blockchain technology in different fields from the perspective of academic research and industry technology. Furthermore, technical challenges and recent developments are also briefly listed. We also looked at the possible future trends of blockchain

Fault feature extraction method based on EWT-SMF and MF-DFA for valve fault of reciprocating compressor

According to the nonlinearity and nonstationarity characteristics of reciprocating compressor vibration signal, a fault feature extraction method of reciprocating compressor based on the empirical wavelet transform (EWT) and state-adaptive morphological filtering (SMF) is proposed. Firstly, an adaptive empirical wavelet transform was used to divide the Fourier spectrum by constructing a scale-space curve, and an appropriate orthogonal wavelet filter bank was constructed to extract the AM-FM component with a tightly-supported Fourier spectrum. Then according to the impact characteristic of the reciprocating compressor vibration signal, the morphological structural elements were constructed with the characteristics of the signal to perform state-adaptive morphological filtering on the partitioned modal functions. Finally, the MF-DFA method of the modal function was quantitatively analyzed and the fault identification was performed. By analyzing the experimental data, it can be shown that the method can effectively identify the fault type of reciprocating compressor valve

Dynamic characteristics and optimal design of the manipulator for automatic tool changer

In order to improve the reliability of changing tool for ATC (automatic tool changer), a horizontal tool changer of machining center is chosen as the example to study the dynamic characteristics in the condition of changing a heavy tool. This paper analyzes the structure and properties of the tool changer by simulation and experiment, and the space trajectory equations of the manipulator and tool are derived. The maximum force is calculated in the processing of changing tool. A virtual platform for the automatic tool changer is built to simulate and verify the dynamic performance of the tool changer; the simulation results show an obvious vibration in the process of changing tool, which increases the probability of failure for changing tool. Moreover, in order to find out the device's vibration reasons, a professional experiment platform is built to test the dynamic characteristics. Based on the testing results for a horizontal tool changer, it is known that the unstable vibration is mainly caused by the collision of the tool. Finally, an optimization method for the manipulator is proposed to reduce this vibration and improve the reliability of the tool changer. The final simulation and experiment results show that the optimized manipulator can grasp the heavy tool stably, and the vibration amplitude is significantly reduced in the process of changing tool