Application of SPCTRAL2 parametric model in estimating spectral solar irradiances over polluted Athens atmosphere

Results obtained using SPCTRAL2 parametric model for the polluted urban atmosphere of Athens, Greece, were analysed and compared with ground level experimental spectral solar irradiance measurements and spectrally integrated solar irradiances in two discrete narrow bands, ultraviolet and visible. For the aerosol characterization, the aerosol optical depth evaluated at 500 nm was used as the basic input parameter. The algorithm used seems to reproduce the experimental solar spectral irradiances adequately depending on the aerosol model used. The results obtained have been explained through mean bias and root mean square statistical deviations and the resultant influence of the aerosol volume spectra.     

烧结车间热工设备隔热层厚度计算与构造

本文就我国南方钢铁厂烧结车间热辐射强度较大的热矿槽、主排气管等热工设备的隔热计算进行了讨论并提出了计算方案。     

用超声波检测信号预报抽油杆剩余寿命

目前研究抽油杆剩余寿命的理论方法没有一种可直接应用于现场,无法直接通过工程检测手段来判断抽油杆的剩余寿命。为此,通过抽油杆疲劳试验,找出裂纹前缘的变化规律,得出裂纹深度与裂纹面积之间的关系、裂纹面积与剩余寿命的关系,借用传统Paris公式的数学模型,通过超声波检测建立了超声波探伤信号与裂纹深度之间的关系式,即裂纹检测信号与裂纹扩展规律之间的关系,从而提出了直接利用超声波探伤信号确定抽油杆剩余寿命的方法。将研究结果与疲劳模拟试验得出的剩余寿命相比较,寿命预测符合率达84%以上。     

YXT—1石材异形铣镗机的研制

本文叙述用于大理石、花岗岩板材深度加工的YXT—1石材异形铣镗机的结构特点,并着重介绍该机的设计原则。     

Some experiments with a simple tabu search algorithm for the manufacturer's pallet loading problem

The manufacturer's pallet loading problem consists in arranging, orthogonally and without overlapping, the maximum number of boxes with dimensions (l,w) or (w,l) onto a rectangular pallet with dimensions (L,W). This problem has been successfully handled by block heuristics, which generate loading patterns composed by one or more blocks where the boxes have the same orientation. A common feature of such methods is that the solutions provided are limited to the so-called first order non-guillotine patterns. In this paper we propose an approach based on the incorporation of simple tabu search (without longer-term memory structures) in block heuristics. Starting from an initial loading pattern, the algorithm performs moves that increase the size of selected blocks in the current pattern; as a result, other blocks are decreased, eliminated or created. Computational results indicate that the approach is capable of generating superior order optimal patterns for difficult instances reported in the literature.     

Lower and upper bounds for the mixed capacitated arc routing problem

This paper presents a linear formulation, valid inequalities, and a lower bounding procedure for the mixed capacitated arc routing problem (MCARP). Moreover, three constructive heuristics and a memetic algorithm are described. Lower and upper bounds have been compared on two sets of randomly generated instances. Computational results show that the average gaps between lower and upper bounds are 0.51% and 0.33%, respectively.     

提高深度剖析拉曼光谱的纵向分辨能力

使用适当似从理论上给出了共焦显微拉曼光谱仪的纵向仪器响应函数，针对相对薄（几个μm)的样品（诸如半导体薄膜材料）给出了一个简化的卷积模型，利用共焦显微拉曼光谱的深度剖析方法，研究了激光晶化后的非晶硅薄膜，并利用反卷积算法，提高了对薄膜纵向结构的分辨能力，发现了激光晶化产生的纳米微晶硅仅位于薄膜中间。     

基于水深和地质条件的海洋平台的选型优化

针对海上油田开发的特点,综合考虑初期投资、建造运营期的安全性、维修费用、耐疲劳及腐蚀性能、施工工期、施工难易程度和对环境的破坏程度等多项条件,建立了基于水深和地质条件的海洋平台多目标选型优化模型。针对我国近海油田开发的特点,将水深划分为6个深度区间,为每一深度区间提供备选的平台型式,同时将海底地质条件划分为4种类别。采用层次分析法来求解这一选型多目标优化模型。将水深、地质资料以及备选的平台型式提供给具有丰富设计和建造经验的专家,请他们根据文中建立的层次结构模型对备选平台方案进行评判。实例分析表明,利用该模型,可以选择出适合给定水深范围和海底地质条件的最佳平台型式,为海洋平台的初步设计和建造提供依据和参考。     

An advanced FEA based force induced error compensation strategy in milling

The study introduces a multi-level machining error compensation approach focused on force-induced errors in machining of thin-wall structures. The prediction algorithm takes into account the deflection of the part in different points of the tool path. The machining conditions are modified at each step when the cutting force and deflection achieve a local equilibrium. The machining errors are predicted using a theoretical flexible force-deflection model. The error compensation is based on optimising the tool path taking into account the predicted milling error. The error compensation scheme is simulated using NC simulation package and is experimentally verified.     

气候变化对湟水径流量影响分析

根据近55年水文气象资料，统计分析了湟水径流量的变化特点及其影响因子，并依据降水、气温、蒸发等主要影响因子与径流量的关系，建立了天然径流量计算公式，计算分析了气候变化和人类活动对湟水径流量的影响。结果表明，随着暖干化趋势加剧，20世纪80年代以来气候变化对湟水径流量的影响幅度不断增大，在80年代、90年代，气候变化和人类活动对径流影响量的比例分别约为2：8与3：7，而2000-2004年影响量的比例已接近5：5。