输入参数对板料成形有限元分析的影响

主要介绍了提高板料成形有限元分析计算效率的几种方法,并通过实验研究了虚拟速度对有限元分析结果的影响。     

近30年的工频磁场生物效应研究──没有定论

近３０年来，国际上关于工频电磁场的生物效应研究非常热烈，研究方法主要是基于流行病学、动物实验和暴露量统计分析，所得出的结论存在很大的非一致性。由于缺乏对工频电磁场如何影响人体健康的根本机理的明确认识，因此至今仍未得出关于该论题的确定性结论。本文在广泛阅读国内外有关文献的基础上，对该课题的研究状况作一综述，旨在加强人们对该课题的认识，指导有待深入的研究方向。关键词##4工频电磁场;流行病学;健康影响     

A New Method for Asymmetrical Abel Inversion Using Fourier-Bessel Expansions

A new asymmetrical Abel inversion is presented for application in asymmetrical data which is obtained from plasma diagnostics on the toroidal plasma system. Asymmetry in the system exists in the direction along chord distribution. This new method is aimed at general measuring configuration, and need not assume integration chords to be parallel (for instance, pinhole configurations). In this new method, the asymmetrical local value is expanded to Fourier-Bessel series, and Fourier terms include the information of asymmetry, The coefficients of the expansions are determined using least-square-fitting method.     

The influence of domain structure on the optical and electrical properties of transparent (Pb,La)(Mg1/3Nb2/3)O3–PbTiO3 ceramics

Transparent (Pb,La)(Mg_1/3Nb_2/3)O₃–PbTiO₃ (PLMNT) ceramics were prepared by two stage sintering method. Two different domain structures were formed in PLMNT transparent ceramics with the same composition by changing the cooling rate. Large strip-like domain structure was formed in rapidly-cooled samples, while fine fingerprint-type domain structure was formed in slowly-cooled samples. The large domain structure in transparent PLMNT ceramics caused light scattering and decreased the transmittance. The cut-off wavelength was also red-shifted for PLMNT ceramics with large domain structure, which was attributed to the inner stress in the ceramics. PLMNT ceramics with different domain structures showed different electrical properties: Compared with PLMNT ceramics with large domain structure, PLMNT ceramics with fine domain structure had smaller coercive field, larger electric field induced strain and lower freezing temperature (T_VF).     

醇水混合溶剂中沉淀无机晶体的研究

文章研究了醇水混合溶剂中无机物沉淀结晶的一些规律。研究结果表明,通过选择合适的实验条件,混合溶剂可以有效调控无机晶体的结晶行为,为控制无机晶体的晶型、形貌、尺寸等提供了可借鉴方法。     

粉煤灰运输方式的技术经济分析

探讨电厂与综合利用企业之间的粉煤灰运输方案的选择,从技术性、经济性等方面具体分析了各种粉煤灰运输方式的优缺点,为企业决策提供建议和指导。     

直接乙醇燃料电池阳极催化剂载体的研究进展

主要介绍燃料电池的重要作用,指出直接乙醇燃料电池的优势以及目前面临的问题,论述直接醇类燃料电池阳极催化剂载体的研究现状,介绍具体的催化剂碳系载体、非碳系载体的优点以及不足之处,并且对直接乙醇燃料电池阳极催化剂载体的发展进行了展望。     

Solvent-resistant porous membranes using poly(ether−ether ketone): preparation and application

Poly(ether−ether ketone) (PEEK) is a linear aromatic macromolecule, which can form semi-crystalline aggregative status, allowing PEEK materials to have strong environment tolerance and excellent physicochemical properties. PEEK materials have become a promising alternative to fabricate particular membranes used in extreme conditions. In the past few decades, many researches and evolutions have emerged in membrane fabrication with PEEK materials and its applications for treating organic solvents and their mixtures; however, there are little systematic and comprehensive literature to summarize fabrication approaches, compile applications, and elaborate PEEK property-structure relationship. In this review, the main approaches to fabricate PEEK-based membranes are illustrated concretely, including conventional thermal-induced and non-solvent-induced phase separation, and novel chemical-induced crystallization; the representative applications in ultrafiltration, nanofiltration and membrane contactor containing organic solvents are demonstrated systematically. Meanwhile, the mechanism to tune PEEK solubility in solvents, which can be achieved by altering monomers in synthesis processes or changing membrane preparation routes, is deeply analyzed. Moreover, the existing problems and the future prospects are also discussed. This review provides positive guidance for designing and fabricating membranes using PEEK and its derivative materials for task-specific applications in harsh conditions.     

Chemically triggered life control of “smart” hydrogels through click and declick reactions

The degradation of polymeric materials is recognized as one of the goals to be fulfilled for the sustainable economy. In this study, a novel methodology was presented to synthesize multiple highly cross-linked polymers (i.e., hydrogels) through amine–thiol scrambling under mild conditions. Amine-terminated poly(ethylene glycol) (PEG-NH₂) was reacted with the representative conjugate acceptors to synthesize hydrogels in organic and aqueous solutions, respectively. The materials above exhibited high water-swelling properties, distributed porous structures, as well as prominent mechanical strengths. It is noteworthy that the mentioned hydrogels could be degraded efficiently in hours to release the original coupling partner, which were induced by ethylene diamine at ambient temperature through amine-amine metathesis. The recovered PEG-NH₂ reagent could be employed again to regenerate hydrogels. Due to the multiple architectures and functions in polymeric synthesis, degradation and regeneration, a new generation of “smart” materials is revealed.     

Biobased Green Lubricants: Physicochemical,Tribological and Toxicological Properties of Fatty Acid Ionic Liquids

Fatty acid ionic liquids (FAILs) were designed and synthesized by combining quaternary ammonium cations with a range of biobased fatty acid anions. They were found to be good and universal lubricants for steel–steel, steel–copper, and steel–aluminum friction pairs, which possess low corrosivities, moderate viscosity indexes, and thermal stabilities compared to commercially available synthetic oil polyalphaolefin (PAO) 10 and traditional ionic liquid (IL) L-F104. Among them, N₁₄₄₄Oct and N₄₄₄₄Oct were found to have far lower toxicity than L-F104. Investigation of the lubricating mechanism revealed that firm and effective physical adsorption and tribochemical reaction films can be easily formed on the sliding surface due to the polarity of the fatty acid anions and the aliphatic tails, which prevent metal–metal contact and further antiwear and reduce friction.