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Complex geometry: Its brief history and its future

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Science China Mathematics 2005年第z1期48卷 47-60页

作者： shing.Tung Yau Department of Mathematics Harvard University CambridgeMA 02138USA

This paper reviews the brief history of complex geometry and looks into itsfuture.

关键词： complex geometry, complex manifold, Kahler manifold, Kahler-Einstein metric.

Geometric aspects of the moduli space of Riemann surfaces

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Science China Mathematics 2005年第z1期48卷 97-122页

作者： shing.Tung Yau Department of Mathematics Harvard University CambridgeMA 02138USA

We describe some recent progress in the study of moduli space of Riemann surfaces in this survey paper. New complete Kahler metrics were introduced on the moduli space and Teichmuller space. Their curvature properties and asymptotic behavior were studied in details. These natural metrics served as bridges to connect all the known canonical metrics, especially the Kahler-Einstein metric. We showed that all the known complete metrics on the moduli space are equivalent and have Poincare type growth. Furthermore,the Kahler-Einstein metric has strongly bounded geometry. This also implied that the logarithm cotangent bundle of the moduli space is stable in the sense of Mumford.

关键词： moduli space Teichmiiller space metric curvature.

Benzene and lead exposure assessment among occupational bus drivers in Bangkok traffic

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Journal of Environmental Sciences 2004年第1期16卷 61-66页

作者： shing.TET LEONG PREECHA LAORTANAKUL Research Lab Supervisor Urban Environmental Engineering and Management ProgramSchool of EnvironmentResource and DevelopmentAsian Institute of TechnologyAffiliated Research Associate G.P.O. Box 4 Klong Luang Pathumthani 12120 Thailand216 Soi Satsana 5 Phya Thai Bangkok 10400 Thailand

Four environmental and biological monitoring sites were strategically established to evaluate benzene and lead exposure assessment at various traffic zones of Bangkok Metropolitan Region(BMR). Biological measurement of 48 non air-conditioned, male bus drivers was carried to study the relationship between individual exposure levels and exposure biomarkers. The study group was further sub-divided into four age groups(16—25, 26—35, 36—45 and 46—55 years old) to monitor the age—related exposure effects. A total of 12 unexposed persons were deliberately chosen as the control group. Measurement of unmetobolized benzene in blood and analysis of urinary tt-Muconic acid urine and urinary creatinine are recommended as biomarkers of benzene exposure. Measurement of lead in blood and urine is also recommended for the biological monitoring of lead exposure. During the monitoring period, benzene and lead levels at Yaowarat Road was C_6H_6: 42.46±3.88 μg/m 3, Pb: 0.29±0.03 μg/m 3 and decreased to C_6H_6: 33.5±1.35 μg/m 3, Pb: 0.13±0.01 μg/m 3 at Phahonyothin Road. Significant difference was established between the nonsmoking exposed group and nonsmoking control group for blood benzene concentrations ( P <0.001, two-tailed, Mann-Whiteney U test). Strong correlations were also found between trans-trans-Muconic acid concentrations in post shift samples and atmospheric benzene concentrations. Similarly, good correlation between all of biomarkers and lead level in air is established from automobile *** analysis revealed that among the occupational population in the urban sites, the driver groups were found to have the highest risk of benzene and lead exposures derived from automobile emission.

关键词： benzene and lead measurement biomarkers exposure assessment human biomonitoring unleaded gasoline

An environmental approach for used oil management in Asian cities: a Bangkok's experience

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Journal of Environmental Sciences 2003年第6期15卷 734-743页

作者： shing.TET LEONG PREECHA LAORTANAKUL Urban Environmental Engineering and Management Program School of Environment Resources and Development Asian Institute of Technology G.P.O. Box 4 Klong Luang Pathumthani 12120 ThailandMailing address: 216 Soi Satsana 5 Phya Thai Bangkok 10400 Thailand

This paper addresses increasing concern about the pollution threat of used oil being illegally dumped and the impact of oil on air pollution and freshwater ecosystems in Asian countries. Used oil is a very serious waste management problem. These results call for management action such as maximising the collection and recovery of used oil. The Thai government recognizes the need to recycle used oil and has been active in encouraging programs to accomplish this goal. Thus unless new approaches and incentives are developed, used oil generation may become an increasing serious problem to our environment. The purpose of this study is to examine the technical and economic feasibility, of recycling used oils. In addition, this paper briefly discusses the problems to be overcome and outlines potential mechanisms for providing the necessary disposal controls in order to maximize the protection to public health and environmental quality from potential hazards posed by used lube oil disposal.

关键词： Bangkok health effects oil pollution recycling used oil collection

COMPUTING HARMONIC MAPS AND CONFORMAL MAPS ON POINT CLOUDS

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Journal of Computational Mathematics 2023年第5期41卷 879-908页

作者： Tianqi Wu shing.Tung Yau Center of Mathematical Sciences and Applications Harvard UniversityCambridgeMA 02138USA Department of Mathematics Harvard UniversityCambridgeMA 02138USA

We use a narrow-band approach to compute harmonic maps and conformal maps for surfaces embedded in the Euclidean 3-space,using point cloud data *** a surface,or a point cloud approximation,we simply use the standard cubic lattice to approximate itsϵ-*** the harmonic map of the surface can be approximated by discrete harmonic maps on *** conformal map,or the surface uniformization,is achieved by minimizing the Dirichlet energy of the harmonic map while deforming the target surface of constant *** propose algorithms and numerical examples for closed surfaces and topological *** the best of the authors’knowledge,our approach provides the first meshless method for computing harmonic maps and uniformizations of higher genus surfaces.

关键词： harmonic maps conformal maps point clouds

Metrics on complex manifolds

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Science China Mathematics 2010年第3期53卷 565-572页

作者： YAU shing.Tung Department of Mathematics Harvard University Cambridge

In this note we discuss various canonical metrics on complex manifolds. A generalization of the Bergman metric is proposed and the relations of metrics on moduli spaces are commented. At last, we review some existence... 详细信息

关键词： intrinsic metrics generalized Bergman metrics Weil-Petersson metric Strominger system

New results on the geometry of the moduli space of Riemann surfaces

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Science China Mathematics 2008年第4期51卷 632-651页

作者： YAU shing.Tung Center of Mathematical Sciences Zhejiang University

We briefly survey our recent results about the Mumford goodness of several canonical metrics on the moduli spaces of Riemann surfaces, including the Weil-Petersson metric, the Ricci metric, the Perturbed Ricci metric and the Kahler-Einstein metric. We prove the dual Nakano negativity of the Weil-Petersson metric. As applications of these results we deduce certain important results about the L 2-cohomology groups of the logarithmic tangent bundle over the compactified moduli spaces.

关键词： moduli spaces canonical metrics good metrics L 2-cohomology 14D20 14H20 32G13 53C55

Spatial/temporal indexing and information visualization genre for environmental digital libraries

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2005年第11期6卷 1235-1248页

作者： CHEN Su-shing.GRUNWALD Sabine Department of Computer ＆ Information Science ＆ Engineering University of Florida Gainesville Florida 32611 USA Department of Soil and Water Science University of Florida Gainesville Florida 32611 USA

Protecting and preserving our environmental systems require the ability to understand the spatio-temporal distri- bution of soils, parent material, topography, and land cover as well as the effects of human activities on ecosystems. Space-time modelling of ecosystems in an environmental digital library is essential for visualizing past, present, and future impacts of changes occurring within such landscapes (e.g., shift in land use practices). In this paper, we describe three novel features, spa- tio-temporal indexing, visualization, and geostatistical genre, for the environmental digital library, Environmental Visualization and Geographic Enterprise System (ENVISAGE), currently in progress at the University of Florida.

关键词： Spatio-temporal indexing Geostatistics GIS (Geographic Information System) Visualization Environmentaldigital library Spatio-temporal search

Health implication among occupational exposed workers in a chromium alloy factory, Thailand

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Journal of Environmental Sciences 2004年第2期16卷 181-186页

作者： S. Muttamara shing.Tet Leong Research Lab Supervisor Urban Environmental Engineering and Management Program School of EnvironmentResources and DevelopmentAsian Institute of Technology G.P.O. Box 4Klong LuangResearch Lab SupervisorUrban Environmental Engineering and Management Program School of EnvironmentResources and DevelopmentAsian Institute of Technology G.P.O. Box 4Klong Luang Pathumthani 12120 ThailandPathumthani 12120 Thailand

This study was conducted to assess the occupational exposure and its health impact on the chromium alloy workers. Environmental and biological monitoring, noise and audiometry measurements were done to evaluate the exposure levels in the factory. A total of 112 non-smoking workers were monitored from July 2001 to August 2002 The results showed that most of the chromium and lead exposures in the factory were below the ACGIH-TWA of 50 μg/m 3 for chromium(Ⅵ) and OSHA-PEL of 50 μg/m 3 for lead. The highest chromium(7 25±0 16 μg/m 3) and lead(14 50±0 29 μg/m 3) concentrations were measured in the vibro room. The results indicated that elevated concentrations of chromium and lead were found in both blood and urine samples especially in those areas which were characterized by poor ventilation. The metal contents in blood and urine samples were significantly correlated with airborne metal concentrations in the factory. The result demonstrated that blood and urinary levels among workers were associated with increasing age and duration of exposure. The background noise level of the factory ranged from 67 6 to 89 2 dBA and was frequently higher than the threshold limit value for noise(90 dBA). According to the audiometric test, the exposed workers showed signs of noise-induced hearing loss. Noise at work continued to be an important factor to hearing loss among exposed workers. In our statistical analysis, a significant hearing loss was established on age effect and year of exposure among the workforce.

关键词： chromium and lead exposure electroplating environmental and biological monitoring audiometry measurement