Performance Analysis and Optimization of a Series Heat Exchangers Organic Rankine Cycle Utilizing Multi-Heat Sources from a Marine Diesel Engine

Organic Rankine Cycle (ORC) is an effective way to recycle waste heat sources of a marine diesel engine. The aim of the present paper is to analyze and optimize the thermoeconomic performance of a Series Heat Exchangers ORC (SHEORC) for recovering energy from jacket water, scavenge air, and exhaust gas. The three sources are combined into three groups of jacket water (JW)→exhaust gas (EG), scavenge air (SA)→exhaust gas, and jacket water→scavenge air→exhaust gas. The influence of fluid mass flow rate, evaporation pressure, and heat source recovery proportion on the thermal performance and economic performance of SHEORC was studied. A single-objective optimization with power output as the objective and multi-objective optimization with exergy efficiency and levelized cost of energy (LCOE) as the objectives are carried out. The analysis results show that in jacket water→exhaust gas and jacket water→scavenge air→exhaust gas source combination, there is an optimal heat recovery proportion through which the SHEORC could obtain the best performance. The optimization results showed that R245ca has the best performance in thermoeconomic performance in all three source combinations. With scavenge air→exhaust, the power output, exergy efficiency, and LCOE are 354.19 kW, 59.02%, and 0.1150 $/kWh, respectively. Integrating the jacket water into the SA→EG group would not increase the power output, but would decrease the LCOE.     

PSF-g-P(PEGMA)的合成及其共混超滤膜的制备与性能研究

以氯甲基化双酚A型聚砜(PSF-CH2Cl)为大分子引发剂,通过原子转移自由基聚合(ATRP)法合成了以聚砜(PSF)为疏水主链、聚(聚乙二醇单甲醚甲基丙烯酸酯)[P(PEGMA)]为亲水侧链的梳状两亲性共聚物PSF-g-P(PEGMA).FT-IR和1H-NMR的表征结果证实了两亲性共聚物的生成.将PSF-g-P(PEGMA)与PSF进行共混,通过浸没沉淀法制备了共混超滤膜.研究发现,引入5 wt%的PSF-g-P(PEGMA),共混膜的孔隙率和平均孔径分别从65.9%和0.08μm提高到81.9%和0.18μm;将共混膜于90℃热水中浸泡24 h后,膜表面O/S从14.63提高到17.16;共混膜的亲水性和抗牛血清蛋白(BSA)吸附性能显著提升.     

超临界二氧化碳体系中PVDF微孔膜的表面接枝改性

超临界二氧化碳（SCCO2）是一种T〉31．1℃,P〉7．38MPa的二氧化碳流体,不仅具有类似于气体的粘度和类似于液体的密度,而且可以通过改变温度或压力控制SCCO2的密度及溶解性．SCCO2对有机小分子具有优良的溶解、扩散和渗透性能,化学惰性,无污染,易于分离,作为一种聚合反应介质,受到学术界日益增多重视．SCCO2极低的粘度使其具有良好的流动性和扩散渗透性能,零表面张力使其对聚合物具有良好的润湿和增塑性,这将促进引发剂和聚合单体向微孔膜的外表面及内表面扩散．利用温度和压力改变SCCO2的溶解性能调整单体在聚合物相和SCCO2相之间的分布,进而控制微孔膜内外表面的接枝程度．所以SCCO2接枝聚合反应对于聚合物膜的表面改性具有极其重要的意义．     

Delay-dependent exponential stability for neural networks with discrete and distributed time-varying delays

This Letter studies the exponential stability for a class of neural networks (NNs) with both discrete and distributed time-varying delays. Under weaker assumptions on the activation functions, by defining a more general type of Lyapunov functionals and developing a new convex combination technique, new less conservative and less complex stability criteria are established to guarantee the global exponential stability of the discussed NNs. The obtained conditions are dependent on both discrete and distributed delays, are expressed in terms of linear matrix inequalities (LMIs), and contain fewer decision variables. Numerical examples are given to illustrate the effectiveness and the less conservatism of the proposed conditions.     

Preparation and characterization of PES/TiO2 composite membranes

Polyethersulfone (PES)/TiO₂ composite membranes were prepared by phase inversion method with nano-TiO₂ as additive. The influence of TiO₂ on the morphologies and the performances of PES/TiO₂ membranes were investigated through the methods of SEM, XRD, TGA, contact angle goniometer, mechanical strength tests and filtration experiments. The results showed that the structure of membrane was not obviously affected by addition of TiO₂, and the performances such as hydrophilicity, thermal stability, mechanical strength and anti-fouling ability of membrane were enhanced through adding TiO₂ nanoparticles. At 0.5 wt.% TiO₂ content, the composite membrane has an excellent performance, however higher TiO₂ content (than 0.5 wt.%) resulted in defective pore structure of the membranes and decline of the performances, such as permeability and mechanical strength. TGA and mechanical strength analyses indicated good compatibility between polymers and TiO₂ nanoparticles.     

芯片毛细管电泳电化学检测

评述了芯片毛细管电泳各种电化学检测尤其是安培检测中工作模式、工作电极、分离电流的消除、应用等方面的进展,并进行了展望。     

Au nanoplate/polypyrrole nanofiber composite film: preparation,characterization and application as SERS substrate

Without any other additives or additional energy, Au nanoplates have been successfully prepared and integrated simultaneously with the dedoped polypyrrole nanofiber film via the in situ reduction of AuCl₄^– on the film surface. The morphology and structure of the as‐prepared composite film are characterized, and its application for surface‐enhanced Raman scattering is also investigated. It has been found that the morphology of as‐prepared Au nanoplates is dependent on the reaction duration, while the density is dependent on the concentration of AuCl₄^– ions in the reaction process. It is suggested that polypyrrole plays dual reducing and structure‐directing roles during the formation of Au nanoplates. Surface‐enhanced Raman scattering study shows that the Au nanoplates give an intensive and enhanced Raman scattering when 4‐aminothiophenol is used as a probing molecule. The employed approach may shed some light on simultaneously fabricating and immobilizing other noble metal micro/nanostructures with unique morphology. Copyright © 2011 John Wiley & Sons, Ltd.     

Location for the right eigenvalues of quaternion matrices

This paper aims to discuss the location for right eigenvalues of quaternion matrices. We will present some different Gerschgorin type theorems for right eigenvalues of quaternion matrices, based on the Gerschgorin type theorem for right eigenvalues of quaternion matrices (Zhang in Linear Algebra Appl. 424:139?C153, 2007), which are used to locate the right eigenvalues of quaternion matrices. We shall conclude this paper with some easily computed regions which are guaranteed to include the right eigenvalues of quaternion matrices in 4D spaces.     

Determination of paralytic shellfish toxins in dinoflagellate Alexandrium tamarense by using isotachophoresis/capillary electrophoresis

Baseline separation of seven paralytic shellfish toxins (PSTs), namely decarbamoylsaxitoxin (dcSTX), saxitoxin (STX), neosaxitoxin (NEO), gonyautoxin-2 (GTX-2), gonyautoxin-3 (GTX-3), gonyautoxin-1 (GTX-1), and gonyautoxin-4 (GTX-4), was achieved by using capillary ITP (CITP)/CE with UV detection. Separation parameters including duration time and voltage in CITP process, separation voltage, and pH and concentration of buffer were optimized. The developed method provided linear responses from 1.3 to 200 microM for the PSTs. The LOD ranged from 0.1 to 0.3 microM. PST extracts from two algal strains of Alexandrium tamarense were analyzed and the toxin concentrations in the samples were quantified with an internal standard method by using NEO as the internal standard. The algal extract of A. tamarense HK9301 contained 332 microM GTX-2 and 224 microM GTX-3, while the PSTs were not detected in the extract of A. tamarense CI01.     

HL-1装置的物理调试(1985)

自1985年4月起正式开展HL-1装置的物理调试,其目的是获得平衡、稳定和比较干净的等离子体,并在此基础上开展初步的物理实验研究。在纵向磁场2.3T下获得等离子体电流135kA,平顶时间150-200ms。等离子体电流的持续时间出乎意料地长达1s,其详细的物理原因尚待深入研究。其它等离子体参数的初步结果为n_e≈ 2.8×10~(13)cm~(-3),T_e≈350-500eV,τ_E≈10ms。