基于遗传算法的装备维修费用优化分配理论及优化方法研究

在美国工业界武器系统咨询委员会提出的郊能公式基础上 ,建立了武器装备效能与维修费用函数关系 ,为武器装备维修费用的优化分配提供了一个标准 .针对多种武器装备维修费用优化 ,建立了一个维修费用分配模型 ,用遗传算法进行了优化 ,并对优化过程进行了详细阐述 .在此基础上开发了装备维修经费优化与管理辅助决策支持系统 .     

Multiwalled carbon nanotubes reinforced poly (ether‐ketone) nanocomposites: Assessment of rheological,mechanical, and electromagnetic shielding properties

This study investigates the effect of multiwalled carbon nanotubes (MWCNTs) content on rheological, mechanical, and EMI shielding properties in Ka band (26.5‐40 GHz) of poly (ether‐ketone) [PEK] prepared by melt compounding using twin screw extruder. Transmission electron microscopy (TEM) and field emission gun scanning electron microscopy (FEG‐SEM) studies were adopted to identify dispersion of nanotubes in PEK matrix. TEM and SEM images showed uniform dispersion of MWCNTs in PEK/MWCNT composites even at loading of 5 wt%. The rheological studies showed that the material experiences viscous (fluid) to elastic (solid) transition at 1 wt% loading beyond which nanotubes form continuous network throughout the matrix which in turn promotes reinforcement. Additionally, Van‐Gurp Palmen plot (phase angle vs complex modulus) and values of damping factor further confirm that the material undergoes viscous to elastic transition at 1 wt% loading. This reinforcement effect of nanotubes is reflected in enhanced mechanical properties (flexural strength and flexural modulus). Flexural strength and flexural modulus of PEK showed an increment of 17% upon incorporation of 5 wt% of MWCNTs. Total shielding effectiveness (SE_T) of −38 dB with very high shielding effectiveness due to absorption (SE_A ~ −34 dB) was observed at 5 wt% loading of MWCNTs in PEK matrix in the frequency range of 26.5‐40 GHz (Ka band).     

Synthesis and electromagnetic shielding behaviour of poly(o‐toluidine)/red mud composite

This paper is an attempt to find out application of red mud in controlling electromagnetic pollution. Composite of PoT/RM has been prepared by in‐situ chemical oxidative polymerization and has been tested for electromagnetic shielding effectiveness. Red mud here acted as a filler material. The incorporation of 50 wt% red mud in the polymer matrix results in a shielding effectiveness of 8.9 dB in 8.2 to 12.4 GHz frequency range (X‐band). Furthermore, the structural analysis, morphology, and magnetization have been studied using XRD, TEM, and VSM techniques, respectively. TEM image of the composite shows the distribution of red mud particles in the polymer matrix. The magnetization decreases on incorporation of red mud in the polymer matrix.     

Comparison between experimental and theoretical values of effectiveness factor in cephalosporin C production process with immobilized cells

Cells ofCephalosporium acretnonium ATCC 48272 immobilized in calcium alginate beads were utilized for cephalosporin C production and the results were compared with those obtained with free cells. The experiments were performed with synthetic medium containing glucose and sucrose as carbon and energy sources. Experimental effectiveness factor values were obtained at various cell and dissolved-oxygen concentrations, considering Monod kinetics for the respiration rate, and were compared with the values calculated with zero-order kinetics in spherical bioparticle. The results showed that the assumption of oxygen limitation by diffusion in the bioparticle was correct, and that cephalosporin C production with immobilized cells is perfectly viable, although a slightly lower rate than that obtained in the free cell process was observed.     

INTRAPARTICLE DIFFUSION EFFECTS IN FISCHER-TROPSCH SYNTHESIS Ⅱ.EFFECTS OF PARTICLE SIZE,TEMPERATURE AND PORE STRUCTURE

lntroductionThccatal}'stcffcctivenessfactorismainl}'affectcdb}'itsporcstructurc-butthcparticlesizeandtcmperaturearcaIsoimportantforthediffesionandrcactionUnderindustrialopcrationconditionsforthcstrongl}'exothermicFischcr-Tropschs}nthcsis(FTS)reaction,temperaturedistributionalongcataI}ticbedisccrtainl}ununiform.andthus,theeffectivcncssfactorsarenaturall}'changcd.Whatisimportantisthatthccffectivcncssfactorsarestrictl}'detcrmincdb}'thcparticlcsizeandcorrcspondingporcparameters.lnvcstigationsont…     

Hydrophobic effect in aqueous solutions of nonelectrolytes. II. Cross-interactions of alkylureas

The heats of mixing of the aqueous solutions of monomethylurea, monoethylurea, 1,3-dimethylurea, 1,3-diethylurea were determined at 25°C. The excess enthalpies obtained are expressed in virial form, in terms of pair and triplet interaction coefficients. A method previously discussed for predicting the excess enthalpies and the interaction coefficients of ternary solutions has been applied to the alkylureas. The large deviations between the experimental and calculated values, led to the modification of that method, which better accounts for the marked mixed character of these substances.     

出流角对旋转涡轮叶片前缘气膜冷却影响

基于频闪拍照和稳态液晶测温技术,实验研究了不同气膜孔出流角对旋转态整级涡轮叶片前缘外壁面的气膜冷却特性的影响。实验中,叶片前缘处的主流雷诺数为6.3378×104。实验转速为574 r/min,对应的旋转数为0.0018。平均吹风比从0.5变化到1.25。射流采用N2,其对应的密度比为1.04。结果表明:展向平均气膜冷效是随吹风比的增加而单调增加的,其中最佳吹风比为M=1.25。对于所有吹风比,在-4.3相似文献   

领导团队相对进步效度的一种动态测评方法

团队管理已经成为现代社会最佳的领导方式，以往的绝对进步效度（Absolute Progress Effectiveness）是通过领导团队绩效的对照期指标的比值来测算，本文应用数据包络分析（DataEnvelopment Amtysis）方法，结合团队成员的有效努力程度，通过个体相对进步指数测算相对进步效度（Relative Progress Effectiveness），真实地反映领导团队在等参照前提下的有效进步程度，有利于领导团队的阶段性自检和渐进性发展。     

New insights on testing the efficiency of methods of pricing and hedging American options

With reference to the evaluation of the speed–precision efficiency of pricing and hedging of American Put options, we present and discuss numerical results obtained on the basis of four different large enough random samples according to the relevance of the American quality (relative importance of the early exercise opportunity) of the options. Here we provide a comparison of the best methods (lattice based numerical methods and an approximation of the American Premium analytical procedure) known in literature along with some key methodological remarks.     

Data-driven hedging of stock index options via deep learning

We develop deep learning models to learn the hedge ratio for S&P500 index options from options data. We compare different combinations of features and show that with sufficient training data, a feedforward neural network model with time to maturity, the Black-Scholes delta and market sentiment as inputs performs the best in the out-of-sample test under daily hedging. This model significantly outperforms delta hedging and a data-driven hedging model. Our results also demonstrate the importance of market sentiment for hedging.