Cu-MOF assisted synthesis of CuS/CdS(H)/CdS(C): Enhanced photocatalytic hydrogen production under visible light

CuS/CdS(H)/CdS(C) photocatalysts were synthesized via the hydrothermal method by employing thiourea, Cd(CH₃COO)₂·3H₂O and copper 1,4-benzenedicarboxylate MOF (CuBDC). The photocatalysts were characterized by XRD, XPS, BET, TEM and UV–vis diffuse reflectance spectra. Interestingly, hexagonal CdS (CdS(H)) and cubic CdS (CdS(C)) were formed with phase junctions in one step when CuBDC was introduced in the synthesis process, in addition, CuS nanoparticles were deposited on CdS. However, only hexagonal CdS was obtained without CuBDC. It demonstrated that CuBDC was not only the precursor of CuS but also the structural modifier for CdS. With the reduction of re-combination of photo-induced electrons and holes caused by phase junctions and the enhancement of visible-light absorptions due to the loading of CuS, all CuS/CdS(H)/CdS(C) photocatalysts had higher photocurrent densities under visible-light irradiation, and consequently the higher rates of H₂ production than pure CdS(H). Typically, the catalyst with 2.89 wt% of Cu showed a highest rate of H₂ evolution at 2042 μmol/g/h.     

资金约束下考虑碳配额质押融资的制造/再制造生产决策研究

本文研究资金约束下制造/再制造企业考虑碳配额质押融资的生产减排决策问题，构建了资金约束时不融资和进行碳配额质押融资两种利润模型，通过算例分析自有资金及减排效用参数对产量、碳排放量和总利润的影响。研究结果表明，进行碳配额质押融资能提高产量增加利润，但也可能导致碳排放总量的增加；企业减排能力与减排效用积累量正相关，资金不足时不融资减排效用积累值较小，选择融资可以为企业未来生产减排实现共赢奠定基础。     

热处理对超硬高速钢M42冷拔材组织和塑性的影响

采用中间退火、炉冷退火及相变退火等工艺处理W2Mo9Cr4VCo8(AISI M42)超硬高速钢冷拔钢丝(Φ5.2 mm、Φ4.96 mm),研究分析了不同组织因素对M42材料形变硬化和塑性的影响规律。结果表明,位错密度、铁素体晶粒度及亚微米级碳化物,在不同程度上影响M42高速钢形变硬化和塑性失稳行为。800℃中间退火和860炉冷退火能够显著降低铁素体位错密度,在一定程度上恢复加工硬化能力、改善M42高速钢加工塑性。860℃加热+750℃等温相变退火能够获得低位错密度、细小晶粒内部弥散分布亚微米碳化物颗粒的均匀复相组织,有利于提高材料加工硬化能力,使M42钢延伸率提升至20%。     

Ballistic resistance of spaced multi-layer plate structures: Experiments on Fibre Reinforced Plastic targets and an analytical framework for calculating the ballistic limit

As the use of complex multi-layer structures in defense, marine, aerospace and automotive applications becomes increasingly common, it is vital that the response of such structures to impact loading is better understood and that engineers have adequate analysis tools to design structures optimised for resistance to ballistic penetration. This paper presents the results of a series of ballistic impact experiments carried out on a range of spaced multi-layer fibre reinforced-plastic (FRP) composite targets, with a constant total number of plies per target, but varying numbers of plies per layer and varying layer arrangements. It is shown that varying the ratio of plies between layers can have a significant effect on resistance to ballistic penetration. In light of these experimental results, the validity of applying the Lambert–Jonas equation to spaced multi-layer structures is discussed and an extended framework developed to determine the ballistic limit of a projectile impacting such a structure. The extended Lambert–Jonas framework is then validated with data from the literature. It is hoped that this framework will allow engineers to quickly determine the optimum layer arrangement to maximise the ballistic resistance of complex spaced multi-layer structures.     

Reinforcements affect mechanical properties and wear behaviors of WC clad layer by gas tungsten arc welding

This work deals with the surface analysis, mechanical properties and wear performances of the clad layer, which is made from tungsten carbide (WC) powders on SKD61 die steel by the gas tungsten arc welding method. According to the experimental results, due to the high hardness and elastic modulus reinforcements (Fe₃W₃C and M₇C₃) existing in the WC clad layer, the WC clad specimen has excellent wear performance at different sliding speeds.According to the wear analysis, wear behaviors of the WC clad layer are two-body abrasion and oxidation wear. In addition, oxidation wear dominates the wear behaviors of the SKD61 die steel specimen at different sliding speeds.     

Directional-stability-aware brake blending control synthesis for over-actuated electric vehicles during straight-line deceleration

For the purpose of both energy regeneration and directional stability enhancement, regenerative and hydraulic blended braking control of an over-actuated electric vehicle equipped with four individual on-board motors during normal straight-line deceleration is studied. System models which include the vehicle dynamics, tire, electric powertrain, and hydraulic brake models are developed. Mechanisms of directional instability of the electric vehicle during straight-line braking are analyzed. To improve the electric vehicle's safety and performance, novel compensation methods through blended braking are studied. On the basis of half-shaft torque estimation, two new regenerative braking control algorithms are proposed. Simulations of the developed control algorithms are carried out during normal straight-line braking maneuvers. The results and discussions demonstrate that the developed approaches are advantageous when compared with the conventional baseline strategy, with respect to both the directional stability and regeneration efficiency, thus validating the feasibility and effectiveness of the controller synthesis.     

Contribution of non-adsorbing polymers to cement dispersion

It has been noticed recently that at low w/c ratios (≤ 0.30), non-adsorbed polycarboxylate (PCE) polymers can contribute as well to cement dispersion. This study aimed at defining more specifically the structural requirement for such non-adsorbing polymers. For this purpose, a cement paste (w/c = 0.30) containing a conventional MPEG PCE superplasticizer was admixed with additional quantities of a polyester polymer prepared via homopolymerization of MPEG methacrylate ester macromonomer, the macromonomer used in the homopolymerization, and the polyethylene glycol contained in the macromonomer. It was found that when admixed individually, all three polymers do not adsorb on cement and cannot fluidize the paste but enhance dispersion and fluidity significantly when combined with the PCE superplasticizer. A potential explanation is that the non-adsorbing polymers act as lubricants between cement, which are particularly densely packed at low w/c ratios. The pore fluid loaded with non-adsorbed polymer exhibits superior lubrication compared to pristine cement pore solution.     

Atomistic simulation of the adsorption of calcium and hydroxyl ions onto portlandite surfaces — towards crystal growth mechanisms

Portlandite is an important constituent of cementitious materials. Consequently the growth of portlandite is of great interest to fully understand the hydration of cement, a process still posing many scientific challenges. In this paper the growth of portlandite in aqueous systems is studied by simulating the adsorption of Ca^2 + and OH⁻ at different portlandite surfaces. For the simulation an adapted version of the Freeman (Freeman et al., 2007) in combination with the TIP4P/2005 (Abascal and Vega, 2005) force field was used for both molecular dynamics, conventional and well-tempered metadynamics calculations. Depending on the structure of the portlandite–water interface, different adsorption sites were observed. Based on these we were able to propose an atomistic mechanism of portlandite growth in different crystallographic directions. The proposed mechanism indicates that different species control the growth in different directions, consistent with experimental observations reported in literature (Arnold, 2004).     

双弹性板矩形空腔内噪声的有源力控制

研究了在弹性板上施加不同参数的有源力对腔内噪声进行控制的问题。构建双弹性板构成的封闭矩形声腔模型，对封闭声腔的结构 声耦合特性进行分析，推导了在封闭声腔有源力控制作用下声压计算公式，给出采用有源力控制的最优控制模型。分析了弹性板在不同参数的次级力源激励下腔内局部声场的声压级响应，并建立了仿真模型对局部声场的减噪效果进行分析。结果表明，合理选择次级力源的参数对控制效果的影响较为明显，且次级力源的个数并非越多越好。