建筑创作的实践与思维

我的童年及少年时代在珠江三角洲的农村度过,然后到广州读书,有着从农村到城市的不同环境的薰陶和人间阅历;1936年大学毕业之后,先从事道路土木工程,解放之后又进入建筑设计与创作领域,有着从工程实践到建筑艺术创作的不同体会与思考。回首几十年中生活、环境、职业的转移和变化所引发的生活及思维的发展,颇有痕迹可寻。乡土田园审美观的孕育12岁之前,生活在珠江口农村中,与广州市郊只一江之隔。这里水网纵横,蕉基鱼塘,田畴聚落,星罗棋布,一派水乡自然景色。在这种天然的田园风光和淳朴人情关系的环境的潜移默化薰陶下,形成了一种乡土田园审…     

Fabrication of 3D chitosan–hydroxyapatite scaffolds using a robotic dispensing system

A new robotic desktop rapid prototyping (RP) system was designed to fabricate scaffolds for tissue engineering applications. The experimental setup consists of a computer-guided desktop robot and a one-component pneumatic dispenser. The dispensing material (chitosan and chitosan–hydroxyapatite (HA) dissolved in acetic acid) was stored in a 30-ml barrel and forced out through a small Teflon-lined nozzle into a dispensing medium (sodium hydroxide–ethanol in ratio of 7:3). Layer-by-layer, the chitosan was fabricated with a preprogramed lay-down pattern. Neutralization of the chitosan forms a gel-like precipitate, and the hydrostatic pressure in the sodium hydroxide (NaOH) solution keeps the cuboid scaffold in shape. Comparison of the freeze-dried scaffold to the wet one showed linear and volumetric shrinkage of about 31% and 62%, respectively. A good attachment between layers allowed the chitosan matrix to form a fully interconnected channel architecture. Results of in vitro cell culture studies revealed the scaffold biocompatibility. The results of this preliminary study using the rapid prototyping robotic dispensing (RPBOD) system demonstrated its potential in fabricating three-dimensional (3D) scaffolds with regular and reproducible macropore architecture.     

Spectroscopic ellipsometry studies of amorphous PZT thin films with various Zr/Ti stoichiometries

Amorphous stoichiometric Pb(Zr _x Ti_{1 – x)}O₃) (PZT) thin films with various values of x were deposited on Si(100) substrates by the sol-gel technique. The influence of Ti content on the optical properties was studied by spectroscopic ellipsometry (SE) in the UV-visible region. Using a four-phase fitting model, the refractive index n and extinction coefficient k was obtained by analyzing the SE spectra. The optical band gap energies E _g for these films were reported under the assumption of a direct band-to-band transition. It has been found that the refractive index, extinction coefficient and band gap energy of the films were functions of the film compositions. The refractive index of the PZT films increases linearly with increasing Ti content. On the other hand, the optical band gap energy of the PZT films decreases with increasing Ti content.     

Extreme Thermal Loading on Steel Bridges in Tropical Region

In the design of highway bridges, it is important to consider the thermal stresses induced by the nonlinear temperature distribution in the bridge deck irrespective of their spans. To cope with this, design temperature profiles are provided by many bridge design codes, which are normally based on extensive research on the thermal behavior of bridges. This paper presents the results of a comprehensive investigation on the thermal behavior of steel bridges carried out in Hong Kong. A method for predicting bridge temperatures from given meteorological conditions is briefly discussed. The theoretical results have been validated by temperature measurements on experimental models mounted on the roof of a building as well as on an existing steel bridge. Both the theoretical and field results confirm the validity of the one-dimensional heat transfer model on which most design codes are based. Values of design thermal loading for a 50-year return period are determined from the statistics of extremes over 40 years of meteorological information in Hong Kong. The design temperature profiles for various types of steel bridge deck with different thickness of bituminous surfacing are developed.     

高速公路几何线形对交通安全的影响分析

从交通安全的角度,分析了交通事故与几何线形的关系;得出道路几何线形是造成交通事故的主要原因之一,从而为相关部门采取措施达到减少交通事故的目的.     

Detection and quantification of palm mid‐fraction in a chocolate model system

The tocopherol and tocotrienol compositions of the genuine cocoa butter (CB) and palm mid‐fraction (PMF) were investigated to introduce a more reliable indicator in detecting PMF in CB. The results suggested that the α‐tocotrienol data presented could be utilised for the detection of the PMF admixture to CB. The PMF was added to CB at different levels. HPLC was used to detect the presence of PMF admixture to CB using α‐tocotrienol as an indicator. The results derived from the model system indicated that increasing the PMF amount at 0–15% to CB resulted in an increase in the concentration of the α‐tocotrienol significantly (P < 0.05). The addition of PMF amount more than 15% did not have any effect on the α‐tocotrienol concentration. A linear plot with a high correlation of 0.9967 was obtained with SE of 1.527. The high correlation obtained indicated good accuracy, reflecting a close relationship between experimental and theoretical predicted value.     

Mission reliability analysis of fault-tolerant multiple-phased systems

Fault-tolerant multiple-phased systems (FTMPS) are defined as systems whose critical components are independently replicated and whose operational life can be partitioned into a set of disjoint periods, called “phases”. Because of their deployment in critical applications, their mission reliability analysis is a task of primary relevance to validate the designs. This paper is focused on the reliability analysis of FTMPS with random phase durations, non-exponentially distributed repair activities and different repair policies. For self-repairable FTMPS with a component-level reconfiguration architecture, we derive several efficient formulations from the underlying structure characteristics for their intraphase behavior analysis. We also present a uniform solution framework of the mission reliability for FTMPS with generally distributed phase durations. Compared with existing methods based on deterministic and stochastic Petri nets or Markov regenerative stochastic Petri nets, our approach is more simple in concept and powerful in computation. Two examples of FTMPS are analyzed to illustrate the advantages of our approach.     

薄膜厚度的多探头计算机实时测控系统

阐述了用声阻抗法实时监测薄膜沉积的原理，介绍了一种使用个人计算机的实时测控系统。它可在真空镀膜的过程中对膜厚进行实时测量和控制，允许使用多个石英晶体探头，以适应多源共蒸发真空镀膜的需要。监测的过程和结果可以存储下来进行分析。为优化镀膜工艺提供了很大的方便。     

煤直接液化用溶剂的研究现状

对前人在煤直接液化研究中所使用的溶剂的种类、作用和优缺点进行综述，指出开发新的溶剂，使煤液化在较低温度和压力下完成并获得高的油收率是煤直接液化更容易实现和产业化的关键。