W-based versus latent variables spatial autoregressive models: evidence from Monte Carlo simulations

In this paper, we compare by means of Monte Carlo simulations two approaches to take spatial autocorrelation into account: the classical spatial autoregressive model and the structural equations model with latent variables. The former accounts for spatial dependence and spillover effects in georeferenced data by means of a spatial weights matrix W. The latter represents spatial dependence and spillover effects by means of a latent variable in the structural (regression) model while the observed spatially lagged variables are related to the latent spatial dependence variable in the measurement model. The simulation results based on Anselin’s Columbus, Ohio, crime data set show that the misspecified latent variables approach slightly trails the correctly specified classical approach in terms of bias and root mean squared error of the coefficient estimators.     

Derivation of equations of motion of an unwinding cable from a cylindrical spool package

In this study, the transient analysis of a cable unwinding from a cylindrical spool package is studied. Cables are withdrawn with a constant velocity through a fixed point which is located along the axis of the package. When the cable is flown out of the package, several dynamic forces, such as inertial force, Coriolis force, centrifugal force, tensile force, and fluid-resistance force are acting on the cable. Consequently, the cable becomes to undergo very nonlinear and complex unwinding behavior which is called unwinding balloon. In this paper, to prevent the problems during unwinding such as tangling or cutting, unwinding behaviors of cables in transient state were derived and analyzed. First of all, the governing equations of motion of cables unwinding from a cylindrical spool package were systematically derived using the extended Hamilton’s principles of an open system in which mass is transported at each boundary. And the modified finite difference methods are suggested to solve the derived nonlinear partial differential equations. Time responses of unwinding cables are calculated using Newmark time integration methods.     

Quality and safety of a new rapeseed ‘Kangyu’ cultivated at different regions in Korea

The quality and safety of rapeseed are greatly affected by glucosinolate and erucic acid. To determine the quality of a new variety, ‘Kangyu’ was cultivated at 3 different regions and analyzed to evaluate oil quality and glucosinolates contents. The new cultivar accumulated 38–43%(w/w) of oil and 5–14 μmol/g of glucosinolates, whereas the local race contained 43% and 52 μmol/g, respectively. The total glucosinolates in ‘Sunmang’ was above the permissible limit. All ‘Kangyu’ samples had safe fatty acid compositions but the local race contained 43% of erucic acid (C22:1) that is far from the International Standard. The contents of oleic (C18:1), linoleic (C18:2), and linolenic acid (C18:3) in ‘Kangyu’ were 61–65, 21–23, and 9–10%, respectively. Consequently, ‘Kangyu’ was good oil source in Korea in terms of erucic acid (C22:1) and total glucosinolates for human health.     

Material characterization of glass/polypropylene composite bone plates according to the forming condition and performance evaluation under a simulated human body environment

The mechanical performance of a composite bone plate made of a glass/polypropylene (Twintex) for the biologic fixation of diaphyseal long bone fractures was investigated in this paper. To find out the most appropriate forming condition of the composite bone plate, tensile and bending tests and microscopic observations of the specimens fabricated by various forming conditions were carried out. The measured mechanical properties, the morphology of the material cross-section, the fibre volume fractions, etc., were mutually correlated, and the results were used for determining the most appropriate forming condition. An environmental test of composite bone plates under a simulated human body also was carried out using the fabricated composite bone plate. The material degradation according to the water-exposure time was quantitatively investigated by a four-point bending test. Finally, the serviceability of the proposed composite bone plate was verified by fatigue tests.     

Low cycle fatigue behavior of die cast Mg-Al-Mn-Ce magnesium alloy简

Fatigue failure is a main failure mode for magnesium and other alloys. It is beneficial for fatigue design and fatigue life improvement to investigate the low cycle fatigue behavior of magnesium alloys. In order to investigate the low cycle fatigue behavior of die cast Mg-AI-Mn-Ce magnesium alloy, the strain controlled fatigue experiments were performed at room temperature and fatigue fracture surfaces of specimens were observed with scanning election microscopy for the alloys under die-cast and aged states. Cyclic stress response curves, strain amplitude versus reversals to failure curve, total strain amplitude versus fatigue life curves and cyclic stress-strain curves of Mg-AI-Mn-Ce alloys were analyzed. The results show that the Mg-AI-Mn-Ce alloys under die-cast （F） and aged （T5） states exhibit cyclic strain hardening under the applied total strain amplitudes, and aging treatment could greatly increase the cyclic stress amplitudes of die cast Mg-AI-Mn-Ce alloys. The relationships between the plastic strain amplitude, the elastic strain amplitude and reversals to failure of Mg-AI-Mn-Ce magnesium alloy under different treatment states could be described by Coffin-Manson and Basquin equations, respectively. Observations on the fatigue fracture surface of specimens reveal that the fatigue cracks initiate on the surface of specimens and propagate transgranularly.     

结构疲劳可靠性分析智能仿真方法

将计算机智能仿真技术用于结构疲劳可靠性寿命评价。采用神经网络建立载荷级，损伤参数量及材料性能对应关系，模拟材料性能变化，采用随机离散仿真方法，建立材料疲劳失效可靠性分析仿真系统。     

Application of infrared thermal testing and mathematical models for studying the temperature distributions of the high-speed waterjet

In this paper, infrared thermal testing and mathematical models for studying the temperature distributions of the high-speed waterjet in air are presented. The waterjet temperature distributions are investigated under different pressures. We describe the experiments in which we apply the infrared thermal imager to obtain the infrared thermal images of the high-speed waterjet. By denoising these infrared thermal images and fitting data, we obtain the isotherms and the temperature variation curves as a function of the distances form the nozzle outlet. In order to calculate the shear stress within the water air boundary layers, multi-phase models are developed. Due to the sophisticated patterns of the multi-component model, the numerical computation is used to obtain the velocity and temperature distribution of the waterjet. The results indicate that the temperature distributions were similar when the pressure is greater than the threshold pressure. This fact is proved by further theoretical computation and experiments data. The paper revealed that the velocity profiles were similar to the temperature profiles in the radial direction at the same cross-sections.     

离心复合轧辊的碳化物带状偏析与早期剥落失效分析

对早期剥落失效的民进行了检验分析，阐述了裂纹的萌生、扩展的机制，指出了碳化物的带状偏析是影响轧辊早期剥落失效的主要原因。提出了避免碳化物带状偏析的有效措施。     

Effect of martensite–austenite constituent on toughness of simulated inter-critically reheated coarse-grained heat-affected zone in X70 pipeline steel

The inter-critically reheated coarse-grained heat-affected zone (ICCGHAZ) of X70 pipeline steel with different second peak temperature and heat input was simulated in this study by means of Gleeble3500 simulator. The volume fraction, size, shape and distribution of martensite–austenite (M–A) constituent were analysed. The toughness of ICCGHAZ and corresponding fractographs were examined. The results showed that the distribution of M–A was strongly influenced by second peak temperature, and M–A constituent with necklace structure at lower second peak temperature led to worse toughness. The volume fraction and size of M–A were strongly affected by heat input, the volume fraction of M–A constituent increased with the increase of heat input; the volume fraction and size of M–A were key factors of toughness deterioration; the interfacial energies and the initiation of crack were related to the shape of M–A constituent.