长治市辛安引水二期工程水锤消除方法及原理

结合工程实例 ,介绍了双速阀、压力波动预止阀、全压高速排气阀在引水工程中的作用 ,通过实践证明 ,采用适当措施 ,能有效预防和消除水锤的危害 ,达到节能降耗的目的     

A new efficient numerical method and the dynamic analysis of composite laminates with piezoelectric layers

Firstly, a numerical method for the inversion of Laplace transform is developed and its accuracy is shown through examples. Then, a state-vector equation for the dynamic problems of piezoelectric plates is deduced directly from a modified mixed variational principle for piezoelectric bodies and its exact solution for the dynamic problems of simply supported rectangle piezoelectric plate is simply given. For multilayered hybrid plates, we derive the solution in terms of the propagator matrices. The techniques accounts for the compatibility of generalized displacements and generalized stresses on the interface both the elastic layers and piezoelectric layers, and the transverse shear deformation and the rotary inertia of laminate are also considered in the global algebraic equation of structure. Meanwhile, there is no restriction on the thickness and the number of layers. As an application of the numerical inversion of Laplace transform presented in this paper, typical numerical examples of the harmonic vibration and transient response are proposed and discussed. Since the highly accurate numerical results, they can serve as benchmarks to test various thick plate theories and various numerical methods, such as the finite and boundary element methods for transient response problems.     

水上地震折射互换法误差分析

在理论上，用源检互换的方法进行折射地震勘探是没有误差的，在某些特殊条件下无法铺设检波器而又必须进行折射地震勘探时它也是唯一的选择，然而，在实际工作中，由于各种因素的影响，其误差是不可忽略的。为此，本文从地震折射运动学的角度对水上地震折射互换法因过河钢丝绳的重量、水的流速和流向、炮点深度等客观因素造成的解释误差进行了分析，揭示了水上地震折射互换法应注意的问题。这对水上地震折射互换法的资料解释进行误差校正提供了理论基础。     

Lactic acid production from dining‐hall food waste by Lactobacillus plantarum using response surface methodology

BACKGROUND: Food waste generally has a high starch content and is rich in nutritional compounds, including lipids and proteins. It therefore represents a potential renewable resource. In this study, dining‐hall food waste was used as a substrate for lactic acid production, and response surface methodology was employed to optimise the fermentation conditions. RESULTS: Lactic acid biosynthesis was significantly affected by the interaction of protease and temperature. Protease, temperature and CaCO₃ had significant linear effects on lactic acid production, while α‐amylase and yeast extract had insignificant effects. The optimal conditions were found to be an α‐amylase activity of 13.86 U g^?1 dried food waste, a protease activity of 2.12 U g^?1 dried food waste, a temperature of 29.31 °C and a CaCO₃ concentration of 62.67 g L^?1, which resulted in a maximum lactic acid concentration of 98.51 g L^?1 (88.75% yield). An increase in inoculum size would be appropriate for accelerating the depletion of initial soluble carbohydrate to enhance the efficiency of α‐amylase in dining‐hall food waste fermentation. CONCLUSION: A suitable regression model for lactic acid production was developed based on the experimental results. Dining‐hall food waste was found to be a good substrate for lactic acid fermentation with high product yield and without nutrient supplementation. Copyright © 2008 Society of Chemical Industry     

Synthesis of nonsharp distillation sequences via genetic programming

This paper addresses the application of Genetic Programming (GP) to the synthesis of multicomponent product nonsharp distillation sequences. Combined with the domain knowledge of chemical engineering, some evolutionary factors are improved, and a set of special encoding method and solving strategy is proposed to deal with this kind of problem. The system structural variable is optimized by GP and the continuous variable is optimized by the simulated annealing algorithm simultaneously. Because GP has an automatic searching function, the optimal solution can be found including distillation, splitting, blending and bypassing operations automatically without any superstructures of nonsharp distillation sequences. Three illustrative examples are presented to demonstrate the effective computational strategies.     

Negative effect of [bmim][PF6] on the catalytic activity of alcohol dehydrogenase: mechanism and prevention

BACKGROUND: [bmim][PF₆] is a hydrophobic ionic liquid which could be considered as an environmentally friendly solvent for biocatalysis. In pure [bmim][PF₆], however, alcohol dehydrogenase from yeast (YADH) has no catalytic activity. The aim of the present work was (1) to quantitatively study the negative effect of [bmim][PF₆] on the catalytic activity of YADH and the related mechanism and (2) to made an attempt to lessen the negative effect of [bmim][PF₆] on YADH by microemulsifying [bmim][PF₆]. RESULTS: The activity of YADH in the homogeneous solution formed by H₂O, CH₃CH₂OH and [bmim][PF₆] decreased rapidly with the increase of the molar fraction of [bmim][PF₆]. The inhibitory effect of [bmim][PF₆] on YADH was probably caused by the competition of the imidazole group of [bmim][PF₆] with the coenzyme NAD⁺ for the binding sites on YADH. In a water‐in‐[bmim][PF₆] microemulsion, YADH was catalytically active due to the formation of the interfacial membrane of the nonionic surfactant TritonX‐100, which separated YADH from [bmim][PF₆] and avoided the direct inactivation of [bmim][PF₆] on YADH. Under optimal conditions, the activity of YADH was as high as 51 µmol L^?1 min^?1. CONCLUSION: [bmim][PF₆] was an inhibitor of YADH and its negative effect on YADH could be lessened by its microemulsification. Copyright © 2008 Society of Chemical Industry     

Validation and modification of WAVE spray model for diesel combustion simulation

In CFD simulation of diesel combustion, the predictive capabilities of the spray model play the most important role. Consequently, under the strict guidelines of the V&V, a method to adjust parameters of diesel spray model WAVE to accompany with the in-cylinder physical progress has been investigated in this paper. Moreover, the simulation of the spray has been validated by high-speed photography experiments and verified by the equation proposed by Hiroyasu. Finally, a modified setup for the WAVE spray model has been proposed and applied in the spray and combustion simulation for Deutz1013 diesel in different engine speed.     

Interfacial polycondensation of diphenolic acid and isophthaloyl chloride

Interfacial polycondensation of diphenolic acid (DPA) and isophthaloyl chloride (IPC) in various solvent/water systems was investigated with tetrabutyl ammonium chloride as a phase transfer catalyst. It was found that a large mass of capsules were formed at the beginning of the reaction for all solvents examined but the capsule morphology and reaction results depended on the solvents. It is believed that the capsule shells make up of the reaction zone and a mechanism of the interfacial polycondensation is proposed accordingly. The effect of the solvents on the reaction was interpreted from the interaction between the polymer and the solvent according to the mechanism. The reaction conditions were optimized, and poly(DPA-IPC) with high intrinsic viscosity was prepared in high yield under the optimal condition. It is an amorphous polymer with glass transition temperature of about 160°C. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Restraining the associations of anthracene fluorophore by chemically linking to poly(methyl methacrylate)

Associations (dimer or aggregate) of anthracene (An) fluorophores tend to interrupt the monomer emission and reduce the quantum yield (Φ_PL); therefore, poly(methyl methacrylate) (PMMA) chain was used in this study to chemically link to anthracene and to block the mutual associations among the anthracene fluorophores. With this aim, the target polymers were prepared by anionic polymerizations with 9,10‐dibromoanthracene/s‐butyllithium as initiating system to proceed polymerizations of methyl methacrylate (MMA) directly or in the presence of 1,1‐diphenylethylene (DPE). Use of DPE before addition of MMA produces stable initiating anionic species and avoids potential side reactions during polymerization; however, it also introduces four β‐phenylene rings around the central anthracene ring, which interfere with the corresponding emission pattern and reduce the Φ_PL (32%) value due to potential interactions between phenylene rings and anthracene. On the contrast, polymerization without participation of DPE results in polymer with central anthracene ring directly connected to two PMMA chains, which gives clean vibronic emission pattern with limited association emissions and enhanced Φ_PL (52%) value. Physical blending of anthracene by PMMA is less efficient to restrain the associations and results in a film of lower Φ_PL (20%). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Green and self-lubricating polyoxymethylene composites filled with low-density polyethylene and rice husk flour

Polyoxymethylene (POM) composites filled with low-density polyethylene (LDPE) and rice husk flour (RHF) were prepared by injection molding. The POM/5 wt % LDPE/7.5 wt % RHF composite exhibited the lowest wear rate, whereas the coefficient of friction remained low, and the POM/5 wt % LDPE/5 wt % RHF composite had the best mechanical properties. X-ray diffraction analysis was carried out, and the worn surfaces were examined with scanning electron microscopy. The results showed that the addition of the filler reduced the crystallinity degree of the POM composites. The main wear mechanism for unfilled POM was adhesion, whereas for the POM composites, wear seemed to occur mainly by fatigue and abrasion. It was experimentally confirmed that the POM composite filled with LDPE and RHF, which is well-performing, low-cost, and environmentally friendly, could be a potential material for tribological applications. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008