基于博弈分析的流域水资源配置

针对传统规划方法难以体现水资源配置过程中多种复杂因素的问题,基于博弈理论建立宏观调控和市场经济相结合的水资源配置动态博弈模型,求解其子博弈精炼纳什均衡下各博弈参与人的策略,并运用改进量子遗传算法求解该博弈模型。对A河流域水资源配置结果表明,在保证流域公共生态用水2.0×10~8 m~3的基础上,各用水子区自发约束自身的取水量,达到均衡时,社会总收益为11.27亿元,相比自由取水模型,社会总收益增加了0.95亿元,增幅为9.2%。     

Mechanism of methanol decomposition on the Pd/WC(0001) surface unveiled by first-principles calculations

In this study, the decomposition of methanol into the CO and H species on the Pd/tungsten carbide (WC)(0001) surface is systematically investigated using periodic density functional theory (DFT) calculations. The possible reaction pathways and intermediates are determined. The results reveal that saturated molecules, i.e., methanol and formaldehyde, adsorb weakly on the Pd/ WC(0001) surface. Both CO and H prefer three-fold sites, with adsorption energies of −1.51 and −2.67 eV, respectively. On the other hand, CH₃O stably binds at three-fold and bridge sites, with an adsorption energy of −2.58 eV. However, most of the other intermediates tend to adsorb to the surface with the carbon and oxygen atoms in their sp³ and hydroxyl-like configurations, respectively. Hence, the C atom of CH₂OH preferentially attaches to the top sites, CHOH and CH₂O adsorb at the bridge sites, while COH and CHO occupy the three-fold sites. The DFT calculations indicate that the rupture of the initial C–H bond promotes the decomposition of CH₃OH and CH₂OH, whereas in the case of CHOH, O–H bond scission is favored over the C–H bond rupture. Thus, the most probable methanol decomposition pathway on the Pd/WC(0001) surface is CH₃OH → CH₂OH → trans-CHOH → CHO → CO. The present study demonstrates that the synergistic effect of WC (as carrier) and Pd (as catalyst) alters the CH₃OH decomposition pathway and reduces the noble metal utilization.     

Chest X-ray enhancement to interpret pneumonia malformation based on fuzzy soft set and Dempster–Shafer theory of evidence

Image enhancement algorithms are commonly used to increase the contrast and visual quality of low-dose x-ray images. This paper proposes an automated enhancement method using soft fuzzy sets with a new decision-making scheme based on Dempster-Shafer theory of evidence for the visual interpretation of pneumonia malformation in low-dose x-ray images, called as XEFSDS. The XEFSDS model first generates an original source x-ray image into a complementary image, then each original and complement image is applied to the characterized image object and background areas of fuzzy space. The S-function is utilized to define fuzzy soft sets for the classification of gray level ambiguity in both images, and hence a decision criterion via Dempster-Shafer approach and fuzzy interval has been adapted to discriminate uncertainties on the pixel intensity and the spatial information. Modified membership grade operations have been performed on each object/background area, and Werner’s AND/OR operator (an aggregation operator) has been utilized to build a new membership function from two modified membership functions. Finally, an enhanced image is obtained from the new membership function via defuzzification. Experiments on different pneumonia X-ray images demonstrate that the XEFSDS scheme produces better results than the existing methods. To show the advantages of the XEFSDS scheme, we have executed a segmentation based examination on enhanced image for the detection of pneumonia malformation as well as abnormal lobe (lobar pneumonia) or bronchopneumonia.     

Component spectroscopic properties of light-harvesting complexes with DFT calculations

Photosynthesis is a fundamental process in biosciences and biotechnology that influences profoundly the research in other disciplines. In this paper, we focus on the characterization of fundamental components, present in pigment-protein complexes, in terms of their spectroscopic properties such as infrared spectra, nuclear magnetic resonance, as well as nuclear quadrupole resonance, which are of critical importance for many applications. Such components include chlorophylls and bacteriochlorophylls. Based on the density functional theory method, we calculate the main spectroscopic characteristics of these components for the Fenna-Matthews-Olson light-harvesting complex, analyze them and compare them with available experimental results. Future outlook is discussed in the context of current and potential applications of the presented results.     

Three-phase four-wire shunt active power filter based on the SOGI filter and Lyapunov function for DC bus control

The three-phase four-wire shunt active power filter (SAPF) was developed to suppress the harmonic currents generated by nonlinear loads, and for the compensation of unbalanced nonlinear load currents, reactive power, and the harmonic neutral current. In this work, we consider instantaneous reactive power theory (PQ theory) for reference current identification based on the following two algorithms: the classic low-pass filter (LPF) and the second-order generalized integrator (SOGI) filter. Furthermore, since an important process in SAPF control is the regulation of the DC bus voltage at the capacitor, a new controller based on the Lyapunov function is also proposed. A complete simulation of the resultant active filtering system confirms its validity, which uses the SOGI filter to extract the reference currents from the distorted line currents, compared with the traditional PQ theory based on LPF. In addition, the simulation performed also demonstrates the superiority of the proposed approach, for DC bus voltage control based on the Lyapunov function, compared with the traditional proportional-integral (PI) controller. Both novel approaches contribute towards an improvement in the overall performance of the system, which consists of a small rise and settling time, a very low or nonexistent overshoot, and the minimization of the total harmonic distortion (THD).     

基于TRIZ理论滤咀排列鼓工装夹具优化设计

针对滤咀排列鼓工装夹具所存在的制造难度大,精度难于保证,效率低的问题。利用TRIZ理论进行分析,根据技术矛盾解决方法并结合问题的实际情况,获得了具体可行的解决方案。经过实践证明,此设计方案是可行的、可靠的,大大缩短了夹具的加工周期,提高了生产效率,节约了成本。     

含芳香氨基酸三肽及其衍生物自由基离子的形成和解离机理研究

铜-配体(L)-三肽组成的三元复合物［Cu(L)M］²⁺，其中，L表示4′-氯-2,2′:6′,2″-三联吡啶(缩写为4Cl-tpy)；M表示酪氨酰-甘氨酰-色氨酸(YGW)及其修饰型三肽(CH₃CO-YGW-OCH₃，缩写 Ac-YGW-OMe)。使用该复合物，通过碰撞诱导解离 (collision-induced dissociation, CID)产生两种自由基离子 (［YGW］^·+和［Ac-YGW-OMe］^·+)。采用串联质谱结合密度泛函理论 (density functional theory, DFT)得到气相稳定结构，并研究其气相解离行为。研究结果表明，［YGW］^·+和［Ac-YGW-OMe］^·+的气相解离行为截然不同，［YGW］^·+主要产生［M-CO₂-116］⁺和［M-CO₂］^·+碎片离子；而［Ac-YGW-OMe］^·+在气相中主要产生［M-CH₃OH］^·+碎片离子。推测这两种离子的气相裂解机理分别为：［YGW］^·+羧基上的质子重排到多肽骨架中羰基氧上，经历 C_α-C键的断裂产生［M-CO₂］^·+、断裂色氨酸侧链 C_β-C_γ键产生［M-CO₂-116］⁺离子；［Ac-YGW-OMe］^·+则先经历质子重排到酯基氧上，然后经过C-O酯键的断裂形成［M-CH₃OH］^·+离子。参与重排的质子可能有3个来源：Ac-YGW-OMe中甘氨酸的C_α-H、色氨酸的C_α-H 或C_β-H，该机理有待进一步验证。本研究将为其他类型多肽及衍生物的结构及气相反应机理研究提供参考。     

User activities and the heterogeneity of urban space:The case of Dahiyat Al Hussein park

Urban researchers have maintained a constant interest in the complexity and continuity of urban space usage. Some have applied actor–network theory (ANT) to investigate the heterogeneity of spaces and present them through the networks of their users’ activities. However, these accounts are predominantly limited in examining the extent to which these spaces may be heterogeneous when exploring such networks. This paper draws on recent ANT scholarship, which employs an ethnographic research conducted in a main park in a housing project at Dahiyat Al Hussein in Amman, Jordan. The findings describe the complex and unpredictable negotiations that occur within spaces by documenting the varieties and interrelations among user activity networks within this common and shared urban space. This research reveals the extent to which spaces, parks in this case, may be heterogeneous by unpacking their usage. The conclusions and insights assert the necessity of paying attention to design detail and creating designs that are responsive to evolving user activities.     

基于ANSYS的双列圆锥滚子轴承预紧力有限元分析

应用赫兹弹性接触理论,首先分析双列圆锥滚子轴承的结构参数、预紧原理及其预紧受力,再运用SolidWorks建立了双列圆锥滚子轴承的三维模型,最后通过ANSYS进行有限元分析计算,得出在不同的预紧载荷下的接触应力和变形,为轴承预紧力分析提供了新的研究方法。     

A variational approach for free vibrating micro-rods with classical and non-classical new boundary conditions accounting for nonlocal strengthening and temperature effects

Abstract

Transverse vibration of a circular cross sectional micro-rod subjected to a new kind of boundary constraints with elastic torsional springs is presented based on nonlocal elasticity. A nonlocal strengthening beam model is utilized and the effect of temperature changing is taken into consideration. The variational method and Hamilton’s principle are applied to derive the governing equation of motion and corresponding boundary conditions. A higher-order partial differential equation that is a typical characteristic of nonlocal strengthening model is developed, and the boundary conditions contain not only classical conditions but also non-classical higher-order conditions. Unlike previous studies which were only concerned with some conventional boundary constraints, we consider more general boundary conditions named elastic torsional spring supports. Such boundary conditions are between the simply supported and clamped ones, and they are closer to the actual constraints of existing engineering structures. Natural frequencies of micro-rods with new boundary constraints are determined via an eigenvalue method and compared with other results in the literature. It is shown that the nonlocal scale factor, thermal parameter, rigidity parameter and torsional spring coefficient play significant roles in free vibration of micro-rods. The research can provide a reference for a large class of boundary conditions ranging from simply supported to clamped micro-rods.