叠加法作弯矩图再讨论

通过对已知荷载作变换，找出给定区间上的弯矩有无极值的简单判别式，进而计算出极值点处的弯矩。在用叠加法作弯矩图时，可由两个端点处及极值点处的弯矩值而准确地画出弯矩图。     

万州长江大桥车桥耦合振动的研究

结合万州长江大桥铁路桥梁的特点．分别建立了车辆的三维离散自由度模型和桥梁的模态模型．通过轮轨作用关系建立了车桥耦合振动的动力模型．并对万州长江大桥的车桥耦合振动进行了研究．分析表明：主梁较柔的大跨度钢桁架桥梁，车辆高速行驶对其动力响应特别是横向动力响应影响显著．     

Mixed numerical-analytical approach for dynamic one-point-bend test modelling

Specimen deformation during a one-point-bend impact test is modelled within 2D linear elasticity framework. Using modal superposition technique, the closed-form solutions for the striker force and dynamic stress intensity factor (DSIF) variation with time are derived. Parameters used in these solutions have been determined using plane stress finite element model of the specimen and approximated polynomially for a wide range of the specimen geometry parameters. The efficiency of the method proposed has been verified by comparison of the analytical results with the experimental data available in the literature and with the results of finite element analysis.     

A Two-Stage Method for an Approximate Calculation of Statically Indeterminate Trusses

The paper presents the principles of a method, which in two simple stages makes possible to carry out the statically calculation of values of forces acting in the fiat static indeterminate trusses. In each stage, it is considered the static determinate truss, scheme of which is obtained after remove the suitable number of members from the basic static indeterminate truss. The both intermediate statically determinate trusses are of the same clear span and they are loaded by forces of half values applied to the corresponding truss nodes. The method applies one of the typical procedures of calculation of the statically determinate trusses and then it is applied in an appropriate way the rule of superposition for obtaining the final values of forces acting in particular members of the basic truss. The values of forces calculated in this way are of a very close approximation to the force values determined in the special and complex ways being considered as the exact calculation methods. The proposed method can be useful mostly but not only for the initial structural design of such systems. The simplicity of the two-stage method justifies an assumption that it can be relatively easy and worthy to adjust to the requirements of the computer aided technology of statically calculation of the complex forms of trusses.     

On the state and stability of fuel cell catalyst inks

Catalyst layers (CL), as an active component of the catalyst coated membrane (CCM), form the heart of the polymer electrolyte membrane fuel cell (PEMFC). For optimum performance of the fuel cell, obtaining suitable structural and functional characteristics for the CL is crucial. Direct tuning of the microstructure and morphology of the CL is non-trivial; hence catalyst inks as CL precursors need to be modulated, which are then applied onto a membrane to form the CCM. Obtaining favorable dispersion characteristics forms an important prerequisite in engineering catalyst inks for large scale manufacturing. In order to facilitate a knowledge-based approach for developing fuel cell inks, this work introduces new tools and methods to study both the dispersion state and stability characteristics, simultaneously. Catalyst inks were prepared using different processing methods, which include stirring and ultrasonication. The proposed tools are used to characterize and elucidate the effects of the processing method. Structural characterization of the dispersed particles and their assemblages was carried out by means of transmission electron microscopy. Analytical centrifugation (AC) was used to study the state and stability of the inks. Herein, we introduce new concepts, S score, and stability trajectory, for a time-resolved assessment of inks in their native state using AC. The findings were validated and rationalized using transmittograms as a direct visualization technique. The flowability of inks was investigated by rheological measurements. It was found that probe sonication only up to an optimum amplitude leads to a highly stable colloidal ink.     

我国绿色环保油墨标准现状及思考

本文介绍了国内外绿色环保油墨标准的现状,分析了我国绿色环保油墨标准存在的问题,提出了建议。     

Effects of Ni2+ concentration on the composition,structure, magnetic properties,and DC-bias superposition characteristics of NiCuZn ferrites

Ni_xCu_0.2Zn_yFe_1.98O₄ (x = 0.16, 0.26, 0.35, 0.43, 0.50; y = 0.8?x) ferrites were prepared via solid-state reaction. The influence of Ni²⁺ concentration on ferrites composition, microstructure, magnetic properties and DC-bias superposition characteristics was studied by XRD, SEM, XPS, and VSM. Then, the effect of magnetic properties on the DC-bias superposition characteristics was analyzed. The results showed that the ferrites sintered at 900 °C for 3 h were all in pure spinel phase with an average grain size of 7.5 μm and a relative density of about 5.15 g cm^?3. With the increase in Ni²⁺ concentration, the saturation magnetization (M_s) and coercivity (H_c) of ferrites increased, but the magnetocrystalline anisotropy constant (K₁) first increased and then decreased. And the M_s, H_c, and K₁ of the specimen with x = 0.43 were 63.62 emu·g^?1, 27.36 Oe, and 1813.17 Oe·emu·g^?1, respectively. In particular, the specimen of x = 0.50 achieved the best DC superposition characteristics, where the H_70% was about 220 A m^?1. The incremental permeability of the specimens decreased rapidly at a bias magnetic field <400 A m^?1. The variation mainly originated from the domain wall displacement, and the rate of decrease was influenced by both M_s and K₁. At a bias magnetic field ≥400 A m^?1, the incremental permeability of the specimens decreased slowly, mainly because the number of domain walls decreased until disappearing, and the specimens tended to become a single domain structure. And the rate of decrease of incremental permeability was mainly affected by K₁.     

Formulating Pantone colors by unused base inks,formulation software,and a spectrophotometer

Unused base inks that are not going to be used for printing production are considered to be hazardous materials. Their disposal is expensive, and strict environmental regulations should be followed for their disposal. As an alternative, this article describes how spectral data of unused base inks can be gathered and mixed to generate new colors to incorporate them back to print production for small‐volume jobs. In this study, 30 different Pantone colors were selected as target colors. The CIE L*a*b* spectral data of Pantone colors and unused base inks were gathered via a spectrophotometer. A commercial formulation software, based on multiflux theory and CIE L*a*b* color space, was used to formulate ink recipes that contained the base inks. To quantify the performance of ink recipes, they were mixed and printed using an offset printability tester. The CIELAB ΔE*_ab metric, developed by CIE, was used to detect the visual differences between the target Pantone Color and printed colors.     

Preparation of P(St-NMA) microsphere inks and their application in photonic crystal patterns with brilliant structural colors

Patterned photonic crystals with structural colors on textile substrates have attracted a special attention due to the great advantages in application, which currently become a research hot-spot. This study utilized an ink-jet printing technology to prepare high-quality photonic crystal patterns with structural colors on polyester substrates. The self-assembly temperature of poly(styrene-N-methylol acrylamide) (P(St-NMA)) microspheres set to construct photonic crystals were deeply optimized. Moreover, the structural colors of prepared photonic crystal patterns were characterized and evaluated. When the mass fraction of P(St-NMA) microspheres was 1.0 wt.%, the pH value ranged from 5 to 7, and the surface tension was in the range of 63.79 to 71.20 mN/m, inks could present the best print performance. At 60 °C, prepared P(St-NMA) microsphere inks were good for printing to obtain patterned photonic crystals with regular arrangement and beautiful structural colors. Specifically, photonic crystals with different colors could be constructed by regulating the diameter of microspheres in inks, and prepared structural colors exhibited distinct iridescent phenomenon. The present results could provide a theoretical basis for the industrial realization of patterned photonic crystals by ink-jet printing technology.     

Inkjet-printed patch antenna emitter for wireless communication application

This research focuses on exploring low-cost and rapid production solutions for fabricating emitters for patch antennas for wireless communication applications. Additive manufacturing technique is employed to fabricate two patch antennas using silver nanoparticle ink on FR4 substrate. Finite-element simulation software, HFSS is used to analyse and predict the theoretical performance of the antenna designs for 2.4?GHz MIMO and 6?GHz wireless data transmission. The fabricated antennas have resonant frequencies closely matching the design values. The work provides a viable solution for fabricating emitters and finally antennas commercially using inkjet printing platform, thus overall reducing the cost and simplifying the process.