A routing algorithm for a single transfer crane to load export containers onto a containership

It is discussed how to route transfer crane during loading operation of export containers in port container terminal. We determine the number of containers which transfer crane picks up at each yard-bay as well as the sequence of yard-bays which transfer crane visits during the tour. The objective is to minimize the total container handling time of the transfer crane including the set-up time at each yard-bay and the travel time between consecutive yard-bays. This routing problem is formulated as an integer programming. An efficient optimizing algorithm is also developed for the crane routing problem.     

一种基于空间特征的自适应对角加载性能的研究

基于TDD-CDMA系统前向与反向链路的互易性，以反向链路的波束成形为基础，分析了在不对称传输情况下前向链路波束成彤、功率控制及信号空间特征之间的联系。首先将前向链路波束调节权值的求解转换为标准的半定规划问题(SDP)，得出权向量与阵列误差之间的近似表达式；其次引入调节权值与加栽量之间的迭代关系，从而得出了阵列响应与自适应加载水平之问的函数表达式及前向链路最优功率分配方案；最后给出了仿真验证及分析。     

Probabilistic fatigue crack growth analysis of spot‐welded joints

This paper presents a probabilistic fatigue crack growth life prediction methodology for spot‐welded joints under variable amplitude loading history. The loading is multi‐axial and is obtained from transient response analysis of a vehicle model using finite‐element analysis. A three‐dimensional (3D) finite element model of a simplified joint with four spot welds is developed, and the static stress analysis of this joint is performed. Then the fatigue crack inside the base material sheet is modelled as a surface crack. Probabilistic crack growth model is combined with the stress analysis result to develop a probabilistic fatigue crack growth life prediction methodology for spot welds. This new method is implemented with MSC/NASTRAN and MSC/FATIGUE and is useful for the reliability assessment of spot‐welded joints against fatigue crack growth.     

基于启发式算法的集装箱配载问题的研究

集装箱配载是一个复杂的组合优化问题，属于NP完全问题，求解难度大．在考虑实际应用中的约束条件下，采用整体装填、空间分割、装载间隙合并等策略，提出了一种基于启发式算法的集装箱配载问题的解决方案．运用举例和对比分析验证了该算法的有效性，能够直接应用于物资的集装箱配载．     

不确定输入对电力负荷预测的影响

有关天气的输入变量不确定性会造成较大的预测偏差 .新方法比使用多层感知器的网络有更准确的预测均值 ,这个新方法包括传统的训练后的神经网络和用来计算预测负荷的均值及置信区间的一组方程 .     

An improved model for the prediction of intra-cell buckling in CFRP sandwich panels under in-plane compressive loading

Local instability in the form of “intra-cell buckling” or “dimpling” is a well-known failure mode in honeycomb-cored sandwich panels with very thin faces. Most work reported on the subject suggests relatively simple design formulae for the estimation of the intra-cell buckling load. It is however widely known that these classical design formulae in some cases considerably underpredict the intra-cell buckling load. In this paper a series of experimental results obtained for different CFRP/honeycomb sandwich panel configurations loaded in compression are presented. The results confirm that the “classical” design formulae provide overly conservative results. During the tests the intra-cell buckling patterns were monitored carefully, and it was observed that the hitherto assumed buckling patterns did not correspond to the experimental observations. Based on these findings a new simplified design formula is suggested, which for the investigated CFRP/honeycomb sandwich panels provides significantly more accurate predictions than the “classical” design formulae.     

Probabilistic approach in high-cycle multiaxial fatigue: volume and surface effects

The stress gradient and the size of a component are known to influence the fatigue strength of metallic components. Indeed, in high‐cycle fatigue, experiments prove that the stress distribution as well as the size of the loaded specimen can be responsible for changes in the fatigue limit (for instance, the fatigue limits in tension and bending are different, and decrease with the size of the specimen). When dealing with multiaxial load conditions, those effects still act but a relevant criterion must be used to account for the complex state of stress. The weakest‐link concept together with a multiaxial endurance criterion based on a microplasticity analysis are then combined to describe the fatigue limit distribution of different metallic materials. Several load conditions are analysed: tension–compression, torsion, rotating bending and plane bending. By means of the proposed model, all the known effects on fatigue strength can be reflected. First, the endurance probability can be adequately predicted for any complex load conditions knowing some reference data from uniaxial fatigue tests. It can be linked to the probability of finding a defect with a critical size. The weakest‐link theory also accounts for the decrease of multiaxial fatigue limit with the stressed volume. For the same load condition (i.e. for the same stress distribution in the volume), the probability of finding a critical defect increases with the component size and then according to the weakest‐link theory the fatigue strength drops. A second model, based only on the damage developed at the surface, is also proposed. While the original Weibull theory makes no distinction between potential initiation sites at the free surface and in the volume and can lead to unsatisfactory predictions when applied to materials containing defects such as nodular cast iron, the new surface approach distinguishes between surface and volume effects.     

2种NdFeB粉末的混炼研究

采用快淬法和雾化法制得的2种不同形貌的NdFeB磁粉,以尼龙12作粘结剂,研究了注射成形粘结磁体的混炼过程。分析了2种磁粉的形貌与粉末粒度及其分布,对混合料的粉末临界充填率、均匀度、流变特性的影响,以及混炼温度对磁性能的影响。     

AFM analysis of the lacunar-canalicular network in demineralized compact bone

Atomic force microscopy has been successfully used to examine a wide range of cellular and biomolecular structures and interactions. The application of atomic force microscopy in the analysis of organs and tissues, however, has been limited. In this study, we present a new method for high-resolution atomic force microscopy imaging of compact bone tissue. We performed atomic force microscopy imaging on demineralized compact bone from bovine tibia to obtain structural information about the bone matrix and the lacunar-canalicular network. Knowledge of the dimensions and distributions of the network allows quantitative analysis of the microfluidics of bone tissue. Results from our study show that (1) the canalicular distribution and dimensions are homogenous in transverse, radial and longitudinal orientations; (2) the lamellae of an osteon consist of alternating high and low bands; (3) the canaliculi follow the contour of lamellar bands and (4) globular structures cover much of the bone matrix, including canalicular walls. Our work demonstrates that atomic force microscopy studies of thin-section tissue samples can provide structural details at nanometre resolution.     

Nonlinear cumulative damage model for multiaxial fatigue

On the basis of the continuum fatigue damage theory, a nonlinear uniaxial fatigue cumulative damage model is first proposed. In order to describe multiaxial fatigue damage characteristics, a nonlinear multiaxial fatigue cumulative damage model is developed based on the critical plane approach. The proposed model can consider the multiaxial fatigue limit, mean hydrostatic pressure and the unseparated characteristic for the damage variables and loading parameters. The recurrence formula of fatigue damage model was derived under multilevel loading, which is used to predict multiaxial fatigue life. The results showed that the proposed nonlinear multiaxial fatigue cumulative damage model is better than Miner’s rule.