A Microcomputer Model for Flood Prediction with Applications

Abstract: A generally applicable mathematical model, tailored for use on a Personal Computer, as the design tool to simulate unsteady flood flow in a network of interconnected rivers has been developed and applied to the Sham Chun River along the border between Hong Kong and the People's Republic of China. The effect on the improved Sham Chun River due to the proposed river training in the River Indus, one of its tributaries, is evaluated. The one-dimensional unsteady flow model itself is broadly applicable to a wide range of hydrologic conditions and varying field situations. It incorporates real hydraulic features including branched channels and 'tidal flats' flooding and drying. The time history of water stages and discharges are computed at any desired location throughout the connected essentially one-dimensional channel network subject to initial and boundary conditions. Details are given of techniques adapted in using the computational scheme to quantify the unsteady flow condition and the means to assure an efficient numerical solution as well as to verify the accuracy of the computed outputs by subjection to carefully selected schematic simplified test cases and real prototype cases with numerical solution method is a useful predictive engineering tool in river design.     

Interaction effects of multiple pool fires

What are the effects of flame behavior of a number of fires burning in close proximity to one another? The results of measurements of burning rates, heat feedback, flame height, and flame trailing are reported for fires involving liquid pools.     

Characteristics of gel chromatography using Sephadex gel for fractionation of soluble organic pollutants

The elution volumes of 46 soluble organic compounds in gel chromatography using Sephadex G-15 and G-25 were measured, and the fractionation of organic pollutants by gel chromatography was discussed. In the case of compounds whose structures consist of some unit structure like polyethyleneglycols and sugars, the elution volume increased with the decrease of molecular weight as expected. But for many low molecular weight compounds, this conventional relationship did not apply. The relations between the elution volume and the chemical structure of organic compounds were also discussed.     

A box beam finite element for the elastic analysis of thin-walled structures

The purpose of this paper is to present a formulation of a curved thin-walled box beam finite element having a variable cross-section with at least one vertical axis of symmetry.

To allow for the effects of warping and distortion, three degrees of freedom have been included in the formulation. These degrees of freedom have been designated as the rate of change of twisting angle, the distortional angle of the cross-section, and the rate of change of distortional angle. The effect of shear lag has also been included.

The element may be used for the elastic analysis of a variety of thin-walled structures and in particular for the preliminary analysis of box bridge decks where a three-dimensional analysis may be unnecessary. The accuracy of the element has been demonstrated by comparison of the results obtained with known results from other methods for some examples.     

The Effect of Agitator Impeller Design on Maximum Shear Stress, and the Resulting Impact on the Flocculation Process

Although it is extensively researched, flocculation in the water-treatment industry lacks a design procedure to assess accurately the performance of the different types of agitator impeller which are available. New high-efficiency, hydrofoil-type impellers offer substantial potential for flocculation duties in many areas, provided that they are applied correctly. This paper highlights the importance of the 'velocity gradient'and the distribution of shear within the agitation system. The objective of the paper is to help engineers to evaluate different types of proprietary impeller designs, using various techniques to examine the shear distribution applied to the system.     

Studies on oxidation of benzo [a] pyrene by sunlight and ozone

The destruction of the carcinogen benzo[a]pyrene (BaP) by light is well known; laboratory workers are routinely advised to cover fluorescent lamps with yellow filters while treating samples containing BaP. However until recently the mechanism of oxidation by sunlight and ozone had not been studied in detail. Concentrations of benzo[a]pyrene in urban air are in the range of 5–10 μg/1000 m³. Oxidant concentrations (predominantly in the form of ozone) are reported to be in the range of 0.01 ppm (22 μg per m³). Thus a sampling system with a filter paper would filter about 22,000 μg of ozone passing through and collect about 5 μg of BaP for analysis. The effect of interactions of such large ozone concentrations with BaP deposited on the filter paper is reported; data for the oxidation rates for benzo[a]pyrene coated on quartz surface and exposed to ozone or sunlight are presented. The oxidation products were analysed by thin-layer chromatography and highpressure liquid chromatography. From about eight products detected in these experiments, three have been identified as quinones based on UV-absorption spectrometry and mass spectrometry. Oxidation rates as high as 100% per hour of exposure are observed when less than 0.1 μg of BaP is coated inside the quartz tubes and exposed to ozone or sunlight. Oxidation rates for benzo[a]pyrene (using tritiated BaP) were determined for two types of experimental conditions. In the first set, tritiated BaP was spotted onto a glass fibre paper and sampling continued for 24 h; the loss of BaP was found to be 88%. In the second set tritiated BaP was spotted at intervals of one hour, for eight hours, while sampling is being carried out and the loss of BaP during the period was estimated to be 50%.     

国际航空货运枢纽港:以航空物流为新竞争优势

20世纪80年代以来,经济全球化促进了亚太地区的一些国家和地区的经济迅速增长,同时也带动了区内航空货运的发展.国际航空货运枢纽港(GTP:Global TransPark)是新经济背景下的一种新型货运机场,对提升区域竞争力有着重要的意义.我国有必要建设GTP,以期在21世纪电子商贸及高科技加工工业的发展上抢先建立滩头阵地.逐渐成熟的香港都会经济区有着"一国两制"的特殊地缘政治和制度优势,因而,在亚洲各竞争中的经济区域中,它是建设亚洲首个、也将是最大的GTP的最佳区位.GTP的建成运作可以提升该都会经济区的总体竞争力,加快其经济重构的步伐.结合区内的其它4个机场,珠海机场有条件发展成为GTP.然而,GTP的建设需要有关机场与地方政府间在关税、制空权、后勤服务以及水陆交通等方面进行协调,这将对该都会经济区的内部合作提出更新的挑战.     

Partitioning of polycyclic aromatic hydrocarbons between dissolved and particulate phases in natural waters

Quantities of polycyclic aromatic hydrocarbons (PAH), some of which are carcinogens, enter natural waters in effuents of coke production and other high-temperature industrial pyrolysis processes. Because of their low water solubilities. PAH compounds are generally considered to occur in particulate form in lakes and rivers. However, present studies of ¹⁴C-anthracene adsorption by autoclaved yeast cells indicated that significant fractions of both dissolved and particulate forms of PAH may exist in natural waters. Quantities of anthracene adsorbed exceeded values for PAH adsorption onto mineral surfaces by more than an order of magnitude: suspended organic material may thus be more important than mineral particles in adsorption of PAH compounds. Adsorption was highly dependent upon the yeast cell concentration, and varied widely through the range of suspended organic solids normally encountered in natural waters. The heat of adsorption (5.2 kcal/mole) was characteristic of a physical adsorptive process. Because ecological effects and pathways of dissolved and particulate PAH may differ, adsorptive partitioning may be important in determining PAH hazards to higher organisms in aquatic food chains, and ultimately to man.     

Application of GaN-based ultraviolet-C light emitting diodes--UV LEDs--for water disinfection

GaN-based ultraviolet-C (UV-C) light emitting diodes (LEDs) are of great interest for water disinfection. They offer significant advantages compared to conventional mercury lamps due to their compact form factor, low power requirements, high efficiency, non-toxicity, and overall robustness. However, despite the significant progress in the performance of semiconductor based UV LEDs that has been achieved in recent years, these devices still suffer from low emission power and relatively short lifetimes. Even the best UV LEDs exhibit external quantum efficiencies of only 1-2%.The objective of this study was to investigate the suitability of GaN-based UV LEDs for water disinfection. The investigation included the evaluation of the performance characteristics of UV LEDs at different operating conditions as well as the design of a UV LED module in view of the requirements for water treatment applications. Bioanalytical testing was conducted using Bacillus subtilis spores as test organism and UV LED modules with emission wavelengths of 269 nm and 282 nm.The results demonstrate the functionality of the developed UV LED disinfection modules. GaN-based UV LEDs effectively inactivated B. subtilis spores during static and flow-through tests applying varying water qualities. The 269 nm LEDs reached a higher level of inactivation than the 282 nm LEDs for the same applied fluence. The lower inactivation achieved by the 282 nm LEDs was compensated by their higher photon flux. First flow-through tests indicate a linear correlation between inactivation and fluence, demonstrating a well designed flow-through reactor. With improved light output and reduced costs, GaN-based UV LEDs can provide a promising alternative for decentralised and mobile water disinfection systems.