香港滨水地区持续发展规划

香港海滨地区的存亡 自1840年开始的填海工程成为调节香港城市发展的核心策略为城市继续发展提供了必需的土地。回顾以往，对于另一个艰巨的挑战来说，这是一种简单的解决方案：香港的山地岛屿地形被证实大部分无法满足城市住宅和商业建筑发展的需要。它还要持续提供额外的建设用地，满足快速增长的人口所需的基础设施和道路：居住建筑,经济发展需要的劳动力空间和燃料都靠填海获得。填海工程发挥着作用,没有其他选择。这种发展模式是香港特有的,导致九龙和香港的海岸线不断靠近从原来的近2000m到现在的800m。     

The effects of run‐of‐river dam spill on Columbia River microplankton

Dams, increasingly common in riverine systems worldwide, are particularly prevalent on the Columbia River (CR) in the United States. Hydroelectric projects, including both storage and run‐of‐river (i.e., minimal storage) structures, on the mainstem CR highly manage water flow, often by releasing water over (rather than through) dams as “spill.” To test the effects of run‐of‐river dam spill on microplankton abundance and composition, we sampled above and below two dams in the lower CR before and during spill conditions in spring 2016 and during and after spill conditions in late summer 2007. We tested the effects of location (i.e., above vs. below dams), spill condition (i.e., before, during, and after spill), and their interaction on microplankton abundance. Generally, diatoms were most abundant during springtime, whereas cyanobacteria were most abundant in late summer. Most taxa were not significantly different in abundance above and below dams, regardless of spill status; although cyanobacteria abundance was marginally higher below dams in summer 2007 (p = .04). Abundances of all taxa were significantly different between pre‐spill and spill periods in spring 2016, whereas only diatom and flagellate abundances were significantly different between spill and post‐spill periods in summer 2007. We conclude that spill conditions may influence microplankton abundance, but are not likely to affect microplankton communities on either side of run‐of‐river dams on the CR. This is important information for dam managers concerned about ecosystem impacts of spill.     

Fracture and impulse based finite-discrete element modeling of fragmentation

A numerical method for fragmentation is presented that combines the finite element method with the impulse-based discrete element method (impulse-based FDEM). In contrast to existing methods, fragments are not represented as a conglomeration of spheres; instead, their shapes are represented using solid modeling techniques, and are the result of multiple fracture growth. Fracture growth within each three-dimensional fragment is controlled by stress intensity factors computed using the finite element method and the reduced virtual integration technique. Non-convex fragment interaction and movement is modeled using impulse dynamics, rather than a penalty-based method. Collisions leading to fracture are handled individually by propagating pre-existing internal flaws and cracks. The method utilizes decoupled geometry and mesh representation, and local failure and propagation criteria. Fractures that reach volume boundaries lead to further fragmentation. The approach is demonstrated by the fragmentation of a sphere, which exhibits a velocity-dependent fragment size distribution. The distribution is characterized by a two-parameter Weibull distribution, an emergent property of the simulation. Results are in good agreement with experimental data.     

Molecular dynamics investigation of the effect of the interatomic potential on steady‐state crack propagation

Abstract

We present molecular dynamics simulations examining the effect of the interatomic potential on steady‐state mode I crack propagation in a two‐dimensional triangular lattice as a function of applied strain. The interatomic potential is the Morse potential whose failure strain exhibits linear variation with its exponential parameter. The limiting crack speed is defined to be the steady‐state crack velocity observed at the onset of instability in steady‐state crack propagation leading to dislocation nucleation or crack branching. For all systems studied, the limiting crack speed is observed to be less than one third the Rayleigh wave speed. The fastest crack propagation in these ideal systems is associated with a material's long‐wavelength elastic properties being dominated by the strength of the nearest‐neighbor bond.     

Assessment of atomistic coarse-graining methods

This paper reviews classical theories of coarse-graining and gives a short introduction to representative coarse-grained atomistic models that were developed based on structure reduction, an assumption of homogenous deformation, and field representation. The applicability and limitations of these coarse-grained models are analyzed on the basis of their theoretical frameworks as well as the coarse-graining methods they employ.     

A variational,finite‐deformation constitutive model for piezoelectric materials

We present a constitutive model for piezoelectric materials. The model is fully variational and supports finite kinematics. The postulated free energy depends on the deformation mapping and an electric vector potential, from which the strain and the electric displacement are derived, respectively. The divergence‐free condition of the electric vector potential is enforced by means of a penalty method, which leads to a positive definite tangent for the system of equations that represent the problem. The performance of the formulation is demonstrated by several examples. Published in 2010 by John Wiley & Sons, Ltd.     

铌钛及铌钒钛微合金钢的高温力学性能研究

采用Gleeble-2000实验机测试了广西柳州钢铁股份公司生产的铌钛及铌钒钛微合金钢铸坯的高温力学性能,得到了这两种钢的第Ⅲ脆性温度区分别为600～850℃和750～900℃,并进行了裂纹敏感性及脆化机理分析.利用扫描电镜对塑性区与脆性区的断口形貌进行了观察分析,为减少铌钛及铌钒钛微合金钢铸坯角横裂纹缺陷提供了理论依据.     

Ethical and professional considerations in divorce and child custody cases.

The provision of psychological (e.g., psychotherapy, coparenting, mediation, collaborative divorce, child custody evaluation) services for families of divorce are growing specialties for many clinical and forensic psychologists. However, practice in domestic relations psychology, such as divorce and custody assessment and testimony, is a high-risk venture for incurring ethics complaints and law suits. The lead article and the three commentaries that follow enumerate the various roles practitioners might play, clarify how each role requires specific skill sets that may be outside one’s particular competence and necessitate additional training, describe how countertransferential issues arise, urge meticulous record keeping, discuss some of the subtleties of confidentiality and the releasing of information, describe how transparency in clarifying expectations leads to a lowering of contentiousness, and provide tips for divorce and forensic practice. The special challenges associated with psychologists being tempted to move beyond their role on a case and those of particularly high-risk situations (e.g., complaints of child abuse or domestic violence) are also discussed. Suggestions are offered to help psychologists better serve the public while taking steps to better inoculate themselves from complaints. (PsycINFO Database Record (c) 2010 APA, all rights reserved)