检索结果-南通市图书馆

End Effect on the Twin-Wire Depth Probe

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 1992年第4期1卷 286-291页

作者： C.y.Liu y.W.wong 等 SchoolofMechanicalandProductionEngineering NanyangTechnologicalInstituteNayangAvenueSingapre2263 Sc

The end effect on the output voltage of a twin-wire depth probe was investigated both theoretically and ex- *** was found that the contribution of the end of the probe to the output voltage depends upon the distance between the boundary and the end of the probe and the geometrical configuration of the probe. By mounting a piece of plate to the end of the electrodes,the end effect can be ***,the size of the plate required to eliminate completely this effect is much larger than that usually mounted on commercially available *** between theoretical and experimental results was *** agreement was obtained.

关键词： twin-wire probe depth probe

SCHEDULING TWO GROUPS OF JOBS WITH INCOMPLETE INFORMATION

在线全文

学校读者我要写书评

暂无评论

Systems Science and Systems Engineering 2003年第1期12卷 73-81页

作者： GuochuanZHANG XiaoqiangCAI C.k.wong DepartmentofMathematics ZhejiangUniversityHangzhou30027P.R.China DepartmentofSystemsEngineeringandEngineeringManagement TheChineseUniversityofHongKongShatinN.T.HongKong DepartmentofComputerScienceandEngineering TheChineseUniversityofHangKongShatinN.T.HongKong

In real world situations, most scheduling problems occur neither as complete off-line nor as complete on-line models. Most likely, a problem arises as an on-line model with some partial information. In this article, we consider such a model. We study the scheduling problem P(n1,n2), where two groups of jobs are to be scheduled. The first job group is available beforehand. As soon as all jobs in the first group are assigned, the second job group appears. The objective is to minimize the longest job completion time (makespan). We show a lower bound of 3/2 even for very special cases. Best possible algorithms are presented for a number of cases. Furthermore, a heuristic is proposed for the general case. The main contribution of this paper is to discuss the impact of the quantity of available information in designing an on-line algorithm. It is interesting to note that the absence of even a little bit information may significantly affect the performance of an algorithm.

关键词： Machine scheduling worst-case analysis on-line algorithm

Heavy metal concentrations in edible bivalves and gastropods available in major markets of the Pearl River Delta

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2001年第2期13卷 210-217页

作者： FANG Zhan-qiang CHEUNG R.y.H. wong M.H. Department of Biology South China Normal UniversityGuangzhou 510631China Department of Biology and Chemistry City University of Hong Kong83 Tat Chee AvenueKowloonHong Kong Institute for Natural Resources and Waste Management and Department of BiologyHong Kong Bapt ist UniversityKowloon TongHong Kong

Molluscs are able to accumulate heavy metals and impose health hazard to consumers. The main objective of the present study is to investigate the heavy metal concentrations in edible bivalves and gastropods available in major markets of the Pearl River Delta. Fourteen species of edible molluscs were purchased from six markets in Hong kong and Guangdong Province. The fresh of these biota were tested for their cadmium (Cd), copper (Cu), zinc (Zn), lead (Pb), nickel (Ni), chromium (Cr), antimony (Sb) and tin (Sn) concentrations (based on wet weight). The results indicated that amongst the 14 edible molluscs, only Cd, Pb, Ni, Cr, Sb and Sn concentrations in three species (Ruditapes philippinarum, Perna viridis and Hemifusus tuba) were within the local regulatory limits. Over 60% of bivalve species exceeded maximum permitted levels of Cd (2 mug/g) and Cr (1 mug/g), while over 40% of gastropod species exceeded the maximum levels of Sb (1 mug/g) and Cr (1 mug/g). Most of the samples collected from Hong kong had significantly higher contents of Pb and Sb, but similar levels of Cd, Cu and Zn when compared with samples collected across the border ( p y). In general, the molluscs purchased in Guangdong markets had higher metal contents than those purchased from the Hong kong markets. When compared with the Provisional Tolerable Weekly Intake or Maximum Acceptable Daily Load recommended by FAO/WHO Expert Committee on Food Additives, Cd levels of five species (Anadara ferruginea, Pinna pectinata, Chlamys nobilis, Babylonia lutosa and Hemifusus terntanus) and Cr levels of seven species ( Anadara ferruginea, Paphia undulata, Pinna pectinata, Babylonia lutosa, Hemifusus terntanus, Cymbium melo and Cipangopaludina chinensis) were higher than both the human daily acceptable limits (for Cd and Cr respectively) and the local regulatory levels (for Cd and Cr respectively).

关键词： heavy metals edible molluscs human health Pearl River Delta

Removal of Lead from Aqueous Solution by Acinetobacter calcoaceticus

在线全文

学校读者我要写书评

暂无评论

Biomedical and Environmental Sciences 1990年第2期3卷 202-210页

作者： N.k.MAk y.k.MOk V.W.D.CHUI M.H.wong Department of Biology Hong Kong Baptist College 224 Waterloo Road Hong Kong

A bacterial strain tolerant to the presence of 400 ppm lead was isolated from digested sewage sludge. The organism was identified as Acinetobacter calcoaceticus var: anitraus (98% confidence). Both viable and formalin-inactivated bacterial cells could remove Pb from an aqueous solution. The Pb-binding ability of inactivated cells was compared with that of a commercial ion-exchange resin, Amberlite IR-I20. The metal-binding ability of A. calcoaceticus followed the sequence Pb≥Cu≥Cr≥ (Cd, Ni, and Zn)≥Co. The ability of the inactivated cells to remove Pb was pH sensitive, and the adsorption process was slightly affected at high temperature (70℃). The adsorption and desorption process worked equally well with A. calcoaceticus embedded in a polyacrylamide gel matrix. (c)1990 Academic Press, Inc.

关键词：柳人

Are state ownership and auditors' locality determinants of asset write-downs? Evidence from China

在线全文

学校读者我要写书评

暂无评论

China Journal of Accounting Research 2018年第4期11卷 385-405页

作者： Pauline W.y.wong Department of Accountancy Hang Seng Management College

After issuing the 1998 Accounting Standards, Chinese regulators implemented additional regulations in 2001 governing write-downs of impaired assets and required assessment of recoverable amounts for four additional asset categories. As the recoverable value cannot be obtained objectively, management can discretionally assess the magnitude of write-downs to affect bottom-line profit. This study used 7258 firm-year observations in China from 1998 to2005 to examine whether the percentage of asset write-downs by statecontrolled firms differs from non-state-controlled firms, conditional upon more conservative financial reporting rules, and investigate whether local auditors support managerial decisions on asset write-downs. The empirical findings support the tendency of state-controlled ownerships to have lower asset write-downs. Local auditors also support managerial decisions on asset write-downs, especially when the companies are controlled by local governments.

关键词： Earnings management Impairments State ownership Auditor locality Political influence

Role of C11-FDG dual-tracer PET-CT scan in metastatic screening of hepatocellular carcinoma-a cost-effectiveness analysis

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Hepatobiliary Surgery and Nutrition 2021年第3期10卷 301-307页

作者： kevin k.W.Chu Albert C.y.Chan ka Wing Ma wong Hoi She Wing Chiu Dai kenneth S.H.Chok Tan To Cheung Chung Mau Lo Department of Surgery The University of Hong KongHong KongChina

Background:We aimed to identify predictive factors for positron emission tomography(PET)-detected hepatocellular carcinoma(HCC)metastasis and a cost-effective approach to preoperative PET-computed tomography(CT)for detecting ***:Clinicopathological and survival data of HCC patients having PET-CT with 18F-fludeoxyglucose(FDG)and 11C-acetate(ACT)following contrast-enhanced CT/magnetic resonance imaging(MRI)for preoperative tumor staging were *** logistic regression was performed to identify predictive factors for PET-detected metastasis.A cost-benefit analysis model was built for the incurred costs and the impact of PET-CT findings on treatment strategy was ***:Totally 152 patients were ***-tracer PET-CT detected metastasis in 17 patients(11%).By multivariate analysis,alpha-fetoprotein(AFP)≥400 ng/mL[relative risk(RR):4.30,95%confidence interval(CI):1.41-13.15,P=0.011]and bilobar disease(RR:3.94,95%CI:1.24-12.52,P=0.014)were independent predictive factors for PET-detected ***-CT findings altered the treatment strategy for 12 patients(7.9%);three partial hepatectomies,eight episodes of transarterial chemoembolization(TACE)and one episode of ablation were avoided,with an estimated cost-saving of US$91,000,$150,000 and$10,600 *** the PET-CT been performed only for patients with AFP≥400 ng/mL or bilobar disease(n=74),metastasis would have been confirmed in 14 patients(18.9%),and the cost-saving per patient was estimated at US$1,***:Dual-tracer PET-CT is cost-effective and useful for preoperative HCC staging in patients with AFP≥400 ng/mL or bilobar *** routine use in preoperative workup for all HCC patients is not *** disease with AFPy procedures and is thus cost-effective for preoperative HCC workup.

关键词： Cost-effectiveness study dual-tracer positron emission tomography-computed tomography(dual-tracer PET-CT) hepatocellular carcinoma(HCC) metastatic screening preoperative investigation

Fiber optical parametric oscillator based on highly nonlinear dispersion-shifted fiber

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Optoelectronics 2013年第1期6卷 25-29页

作者： Sigang yANG kenneth k. y. wong Minghua CHEN Shizhong XIE Tsinghua National Laboratory for Information Science and Technology (TNList) Department of Electrical Engineering Tsinghua University Beijing 100084 China The Photonic Systems Research Laboratory Department of Electrical and Electronic Engineering The University of Hong Kong Hong Kong China

The development of fiber optical parametric oscillators (FOPO) based on highly nonlinear dispersion-shifted fiber is reviewed in this paper. Firstly, the background and motivation are introduced, and it is pointed out that the FOPO is promising to act as optical source in non-conventional wavelength bands. Subsequently, the context focuses principally on the problem of inherent multiple-longitudinal-mode characteristic of FOPO and the corresponding solutions to it. The primary technique is by locking the phase of multiple longitudinal modes. The first reported actively mode locked FOPO is also presented in this article. However, it is not probable to realize passively mode locked FOPO because of the random phase dithering of the pump required for suppressing stimulated Brillouin scattering. Furthermore, a regeneratively mode locked FOPO is demonstrated, which can generate wide band tunable radiation in nonconventional wavelengths. Besides mode locked FOPO, the single-longitudinal-mode FOPO is also introduced. Finally, potential future directions are discussed.

关键词： fiber optical parametric amplifier (FOPA) fiber optical parametric oscillator (FOPO) mode locking single longitudinal mode

On Systems of Boundary Value Problems for Differential Inclusions

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2007年第3期23卷 549-556页

作者： Lynn ERBE Christopher C.TISDELL Patricia J.y.wong Department of Mathematics The University of Nebraska-LincolnLincolnNE 68588-0130USA School of Mathematics and Statistics The University of New South WalesSydney 2052Australia School of Electrical and Electronic Engineering Nanyang Technological University50 Nanyan9 AvenueSingapore 639798Singapore

Herein we consider the existence of solutions to second-order, two-point boundary value problems （BVPs） for systems of ordinary differential inclusions. Some new Bernstein-Nagumo conditions are presented that ensure a priori bounds on the derivative of solutions to the differential inclusion. These a priori bound results are then applied, in conjunction with appropriate topological methods, to prove some new existence theorems for solutions to systems of BVPs for differential inclusions. The new conditions allow of the treatment of systems of BVPs without growth restrictions.

关键词： boundary value problem, systems of differential inclusions, existence of solutions a priori bounds Bernstein-Nagumo condition

Ultrafast laser-scanning time-stretch imaging at visible wavelengths

在线全文

学校读者我要写书评

暂无评论

Light(Science & Applications) 2016年第1期5卷 303-312页

作者： Jiang-Lai Wu yi-Qing Xu Jing-Jiang Xu Xiao-Ming Wei Antony CS Chan Anson HL Tang Andy kS Lau Bob MF Chung Ho Cheung Shum Edmund y Lam kenneth ky wong kevin k Tsia Department of Electrical and Electronic Engineering The University of Hong KongPokfulam RoadHong Kong 999077China Department of Bioengineering University of WashingtonSeattleWashington 98195USA Department of Mechanical Engineering The University of Hong KongPokfulam RoadHong Kong 999077China

Optical time-stretch imaging enables the continuous capture of non-repetitive events in real time at a line-scan rate of tens of MHz—a distinct advantage for the ultrafast dynamics monitoring and high-throughput screening that are widely needed in biological ***,its potential is limited by the technical challenge of achieving significant pulse stretching(that is,high temporal dispersion)and low optical loss,which are the critical factors influencing imaging quality,in the visible spectrum demanded in many of these *** present a new pulse-stretching technique,termed free-space angular-chirpenhanced delay(FACED),with three distinguishing features absent in the prevailing dispersive-fiber-based implementations:(1)it generates substantial,reconfigurable temporal dispersion in free space(41 ns nm^(−1))with low intrinsic loss(o6 dB)at visible wavelengths;(2)its wavelength-invariant pulse-stretching operation introduces a new paradigm in time-stretch imaging,which can now be implemented both with and without spectral encoding;and(3)pulse stretching in FACED inherently provides an ultrafast all-optical laser-beam scanning mechanism at a line-scan rate of tens of *** FACED,we demonstrate not only ultrafast laser-scanning time-stretch imaging with superior bright-field image quality compared with previous work but also,for the first time,MHz fluorescence and colorized time-stretch *** results show that this technique could enable a wider scope of applications in high-speed and high-throughput biological microscopy that were once out of reach.

关键词： optical time-stretch imaging pulse stretching ultrafast laser scanning