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A pine/co-PES composite (PCPES composite) was proposed as the feedstock for powder bed fusion (laser sintering, LS). This paper aims to provide some necessary experimental data and the theoretical foundation for LS of pine/co-PES, especially for the application of using the laser-sintered pine/co-PES parts as complex structural patterns in investment casting.

The PCPES composites with different pine loadings were mixed mechanically. The composite’s preheating temperature and processing temperature during LS were determined experimentally based on the material’s thermal behavior. The effects of pine powder on the binding mechanism of PCPES composites were discussed through analyzing the microstructure of the laser-sintered parts’. Mechanical properties and dimensional precision of laser-sintered PCPES parts in different pine loadings were tested, and the parts’ mechanical properties were strengthened by wax-infiltration post-processing. The influence extents of process parameters on the mechanical properties of laser-sintered 20 Wt.% pine/co-PES parts were investigated using a 1/2 fractional factorials experiment.

20 Wt.% pine/co-PES is considered to be a promising wood-plastic composite for laser sintering. The relationship between mechanical strength of its laser-sintered parts and process parameters was built up using mathematical formulas. Experimental results show density, tensile strength, flexural strength and surface roughness of laser-sintered 20 Wt.% pine/co-PES parts are improved by 72.7-75.0%, 21.9-111.3%, 26.8-86.2%, 27.0-29.1% after post-process infiltration with a wax. A promising application of the wax-infiltrated laser-sintered parts is for investment casting cores and patterns.

The proper process parameters and forming properties of laser-sintered parts are limited to the results of laser sintering experiments carried on using AFS 360 rapid prototyping device.

This investigation not only provides a new feedstock for laser sintering with the advantages of low cost and fabricability but also uses an advanced technique to produce personalized wood-plastic parts efficiently. Mathematical models between mechanical properties of laser-sintered PCPES parts and LS process parameters will guide the further LS experiments using the 20 Wt.% pine/co-PES composite. Besides, the laser-sintered PCPES parts after wax-infiltration post-processing are promising as complex structural patterns for use in investment casting.

This paper aims to discuss that a WC/Co-Cr alloy coating was applied to the surface of H13 steel by laser cladding.

The oxidation behavior of the WC/Co-Cr alloy coating at 600°C was investigated by comparing it with the performance of the steel substrate to better understand the thermal stability of H13 steel.

The results showed that the WC/Co-Cr alloy coating exhibited better high-temperature oxidation resistance and thermal stability than did uncoated H13 steel. The coated H13 steel had a lower mass gain rate and higher microhardness than did the substrate after different oxidation times.

The WC/Co-Cr alloy coating was composed of e-Co, CW3, Co6W6C, Cr23C6 and Cr7C3; this mixture offered good thermal stability and better high-temperature oxidation resistance.

This paper aims to clarify the relationship between the cone bit seal failure and the down-hole drilling fluid pressure and high temperature that occur during ultra-deep well drilling. It proposes that the contact pressure distribution under low pressure conditions is favourable for lubrication and the seal inner wear is serious under high pressure conditions. Furthermore, the more reliable cone bit seal can be obtained using the back propagation (BP) neural network and genetic algorithm (GA) to reduce the drilling cost.

The wear morphologies of the seal surface were analyzed using Contour GT-K to determine the seal contact pressure distribution. Then, the influences of the drilling fluid pressure and high temperature on the metal seal interface were analyzed using finite element method. The structural parameters of the seal under high pressure were optimized based on the BP neural network and GA.

This paper proposes that the inner seal contact pressure increases rapidly with an increase in the drilling fluid pressure. The design parameters of the seal components should be adjusted reasonably to ensure that the outer contact pressure is greater than the inner contact pressure, which is advantageous for forming a lubricant film on the inner side of the seal. The uneven temperature distribution of the seal surface will further aggravate seal failure.

Study on the bit seal with good property is significant in drilling application, and the optimized seal can prolong the cone bit life.

The purpose of this paper is to investigate the dissipative filtering problem for a flexible manipulator (FM) with randomly occurring uncertainties and randomly occurring missing data.

The randomly occurring phenomena during the filtering procedure are described by Bernoulli sequences. Based on the idea of dissipative theory, the distributed filtering error augmented system is derived for ensuring the prescribed dissipative performance.

By constructing appropriate Lyapunov function, sufficient dissipative filtering conditions are derived such that the filtering error can be approaching zero. Then, the desired distributed filter gains are designed with the help of matrix transformation.

The merit of this paper is proposing a novel distributed filtering framework for an FM with external disturbance under the dissipative framework, which can provide a more applicable filter design.

This paper builds on and extends the theory of planned behavior (TPB) by examining empirically the underlying mechanism through which red tape is associated with employee change-supportive intention (CSI). It investigates red tape as an antecedent of CSI and examines the mediation role of change-related attitude, subjective norm and perceived behavioral control (PBC) in the relationship between red tape and CSI.

To test the study's hypotheses, cross-sectional data were collected from 183 employees working at a public organization in the Kurdistan Region of Iraq that was going through a major change. Regression analyses and the PROCESS macro for SPSS were used.

Consistent with our expectations, the results indicate that red tape negatively predicts CSI. Red tape also predicts change-related attitude, subjective norm and PBC, which consequently predict CSI. The results also reveal that the relationship between red tape and CSI is mediated by change-related attitude and subjective norm.

The study is limited in using cross-sectional data at a point in time and in investigating intention only, rather than actual behavior.

While prior work shows that red tape is a relevant factor that may affect employee responses to change in public sector, the psychological processes on which this relationship is based are still not fully explained. Therefore, this is the first study that aims to shed some light on this relationship.

The purpose of this paper is to solve the problems of poor mechanical properties, high surface roughness and waste support materials of thin-walled parts fabricated by flat-layered additive manufacturing process.

This paper proposes a curved-layered material extrusion modeling process with a five-axis motion mechanism. This process has advantages of the platform rotating, non-support printing and three-dimensional printing path. First, the authors present a curved-layered algorithm by offsetting the bottom surface into a series of conformal surfaces and a toolpath generation algorithm based on the geodesic distance field in each conformal surface. Second, they introduce a parallel five-axis printing machine consisting of a printing head fixed on a delta-type manipulator and a rotary platform on a spherical parallel machine.

Mechanical experiments show the failure force of the five-axis printed samples is 153% higher than that of the three-axis printed samples. Forming experiments show that the surface roughness significantly decreases from 42.09 to 18.31 µm, and in addition, the material consumption reduces by 42.90%. These data indicate the curved-layered algorithm and five-axis motion mechanism in this paper could effectively improve mechanical properties and the surface roughness of thin-walled parts, and realize non-support printing. These methods also have reference value for other additive manufacturing processes.

Previous researchers mostly focus on printing simple shapes such as arch or “T”-like shape. In contrast, this study sets out to explore the algorithm and benefits of modeling thin-walled parts by a five-axis machine. Several validated models would allow comparability in five-axis printing.

The purpose of this paper is to solve the tracking problem for free-floating space manipulators (FFSMs) in task space with parameter uncertainties and external disturbance.

In this paper, the novel cerebellar model articulation controller (CMAC) is designed with the feedback controller. More precisely, the parameter uncertainties in the FFSM are considered for achieving the robustness.

By using the dynamically equivalent model, the CMAC can be designed and trained with the desired performance, such that the prescribed trajectory can be followed accordingly. The simulation results are presented for illustrating the validity of the derived results.

Based on the designed CMAC, the tracking error would be approaching zero by choosing appropriate quantization level in CMAC and the corresponding learning rules can be tuned online.

The operating wagon records were produced from distinct railway information systems, which resulted in the wagon routing record with the same oriental destination (OD) was different. This phenomenon has brought considerable difficulties to the railway wagon flow forecast. Some were because of poor data quality, which misled the actual prediction, while others were because of the existence of another actual wagon routings. This paper aims at finding all the wagon routing locus patterns from the history records, and thus puts forward an intelligent recognition method for the actual routing locus pattern of railway wagon flow based on SST algorithm.

Based on the big data of railway wagon flow records, the routing metadata model is constructed, and the historical data and real-time data are fused to improve the reliability of the path forecast results in the work of railway wagon flow forecast. Based on the division of spatial characteristics and the reduction of dimension in the distributary station, the improved Simhash algorithm is used to calculate the routing fingerprint. Combined with Squared Error Adjacency Matrix Clustering algorithm and Tarjan algorithm, the fingerprint similarity is calculated, the spatial characteristics are clustering and identified, the routing locus mode is formed and then the intelligent recognition of the actual wagon flow routing locus is realized.

This paper puts forward a more realistic method of railway wagon routing pattern recognition algorithm. The problem of traditional railway wagon routing planning is converted into the routing locus pattern recognition problem, and the wagon routing pattern of all OD streams is excavated from the historical data results. The analysis is carried out from three aspects: routing metadata, routing locus fingerprint and routing locus pattern. Then, the intelligent recognition SST-based algorithm of railway wagon routing locus pattern is proposed, which combines the history data and instant data to improve the reliability of the wagon routing selection result. Finally, railway wagon routing locus could be found out accurately, and the case study tests the validity of the algorithm.

Before the forecasting work of railway wagon flow, it needs to know how many kinds of wagon routing locus exist in a certain OD. Mining all the OD routing locus patterns from the railway wagon operating records is helpful to forecast the future routing combined with the wagon characteristics. The work of this paper is the basis of the railway wagon routing forecast.

As the basis of the railway wagon routing forecast, this research not only improves the accuracy and efficiency for the railway wagon routing forecast but also provides the further support of decision-making for the railway freight transportation organization.

In this paper, the interaction kinetics between eutectic PbSn solder and Au/Ni/Cu metallisation of plastic ball grid array packages during laser reflow bumping were investigated. The effects of processing variables, including laser reflow power and time, on the morphology of the intermetallic compounds formed at the solder/pad interface were studied by scanning electron microscopy and energy dispersive X‐ray spectrometry. Furthermore, dissolution and diffusion of Au and Sn inside the solder bump within the duration of the laser heating was analysed by Auger electron spectroscopy (AES). The results reveal that the morphology of the intermetallic compounds was strongly influenced by the laser input energy. The AES results showed that Au atoms dissolved rapidly into the solder after the solder was melted.

The purpose of this paper is to achieve numerical simulation of cohesive crack growth in concrete structures.

The extended finite element method (XFEM) using four-node quadrilateral element associated with the fictitious cohesive crack model is used. A mixed-mode traction-separation law is assumed for the cohesive crack in the fracture process zone (FPZ). Enrichments are considered for both partly and fully cracked elements, and it thus makes the evolution of crack to any location inside the element possible. In all. two new solution procedures based on Newton-Raphson method, which differ from the approach suggested by Zi and Belytschko (2003), are presented to solve the nonlinear system of equations. The present formulation results in a symmetric tangent matrix, conveniently in finite element implementation and programming.

The inconvenience in solving the inversion of an unsymmetrical Jacobian matrix encountered in the existing approach is avoided. Numerical results evidently confirm the accuracy of the proposed approach. It is concluded that the developed XFEM approach is especially suitable in simulating cohesive crack growth in concrete structures.

Multiple cracks and crack growth in reinforced concretes should be considered in further studies.

The research paper presents a very useful and accurate numerical method for engineering application problems that has ability to numerically simulate the cohesive crack growth of concrete structures.

The research paper provides a new numerical approach using two new solution procedures in solving nonlinear system of equations for cohesive crack growth in concrete structures that is very convenient in programming and implementation.