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Study on impact factors of tracer gas method in investigations of gaseous pollutant transport and building ventilation

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Building Simulation 2023年第3期16卷 413-426页

作者： Naiping Gao Ruge Wang Yan wu zhu wu School of Mechanical Engineering Tongji UniversityShanghai201804China Baoye Group Co.LTD Zhejiang312000China

Building ventilation is essential to discharge indoor pollutants and improve indoor air quality for occupant *** gas method is an efficient way in the field of building ventilation to measure ventilation rate and to evaluate the ventilation *** shows notable deviation of measured ventilation rate using different tracer *** the present study,CFD simulations are carried out to analyze He-,CO_(2)-and SF_(6)-based tracer gas *** effects of tracer gas density and release rate on the concentration distribution and ventilation effectiveness are *** application scenarios of different ventilation rates and airflow distribution forms are *** results show that the deviation of ventilation effectiveness evaluated by different tracer gases can be above 2-4 times,and the error is introduced by non-passive *** tracer gas dispersion is passive or not depends on the relative importance of density difference driven mass transfer to forced convection mass transfer,which is due to the combined effects of density difference,release rate,and indoor airflow velocity,and can be judged by a dimensionless number θ.Under the geometry and ventilation settings in the present study,the critical value of θ is 1.0 for the error range of 5%,and 2.0 for the error range of 10%.When θ is below the critical value,the gas transport is passive and dominated by the indoor ventilation airflow.A release of tracer gas with smaller release rate and smaller density difference into a stronger indoor airflow behaves more *** tracer gas tends to significantly overestimate the performance of upper supply and lower exhaust ventilation,and lighter tracer gas aggravates the overestimation of the performance for lower supply and upper exhaust *** mechanical ventilation rooms with air change rate of 3.0-6.0 h^(−1),a continuous release of tracer gas SF_(6),CO_(2) or He with release rate above 8 mg/s or source concentrati

关键词： building ventilation tracer gas method passive dispersion non-passive dispersion ventilation effectiveness

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Thermal insulation design of subsea vertical X-mas tree

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Petroleum Science 2021年第4期18卷 1182-1194页

作者： Xin Rong Hong-wu zhu College of Mechanical and Transportation Engineering China University of PetroleumBeijing102249China

Temperature drop is commonly observed in subsea vertical X-mas trees during *** presence of a huge temperature difference between internal crude oil and external seawater can cause severe equipment degradation of the oil flow channel(e.g.,hydrate precipitation),which can block the oil flow channel and interrupt the production *** most vulnerable parts of a subsea vertical X-mas tree tend to be components with high convective heat transfer rates,such as production modules and short *** proposed an innovative approach for the insulation design of underwater equipment under a shutdown ***,we obtained a heat transfer analysis of the tree under working conditions through computational fluid dynamics to ascertain the initial temperature condition for an unsteadystate ***,we investigated the unsteady heat transfer characteristics of the tree with an insulation layer in the shutdown state and derived the relationships between insulation duration and thickness by data *** used data analysis to identify the relationship between insulation duration and ***,we derived the empirical formula of insulation thickness for underwater equipment given the effect of environmental factors on the heat preservation *** performed the experiment with an oil pipeline,and the results showed that the internal oil of the equipment did not hydrate within 8 h under the shutdown condition with insulation layers.

关键词： Subsea vertical X-mas tree Thermal insulation design Unsteady heat-transfer analysis Computational fluid dynamics

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Mobilities and leachabilities of heavy metals in sludge with humus soil

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Journal of Environmental Sciences 2011年第2期23卷 247-254页

作者： Rui zhu Min wu Jian Yang State Key Laboratory of Pollution Control and Resources Reuse Tongji University Shanghai 200092 China.

Chemical forms of Zn, Ni, Cu, and Pb in municipal sewage sludge were investigated by adding humus soil to sludge and by performing sequential extraction procedures. In the final sludge mixtures, Zn and Ni were mainly found in Fe/Mn oxide-bound （F3） and organic matter/sulfide-bound （F4） forms. For Zn, exchangeable （F1）, carbonate-bound （F2）, and F3 forms were transformed to F4 and residual forms （F5）. For Ni, F1 and F2 forms were transformed to F1, F2, and F3 forms. Both Cu and Pb were strongly associated with the stable forms F4 and F5. For Cu, F2 and F3 forms were major contributors, while for Pb, F3 and F4 forms were major contributors to F5. Humus soil dosage and pH conditions in the sludge were strongly correlated with the forms of heavy metals. Five forms were used to evaluate metal mobilities in the initial and final sludge mixtures. The mobilities of the four heavy metals studied decreased after 28 days. The metal mobilities in the final sludge mixtures were ranked in the following order： Ni 〉 Zn 〉 Cu = Pb. Leaching tests showed that the mobilities of Zn and Ni in lower pH conditions （pH 4） were higher than those in higher pH conditions （pH 8）.

关键词： sludge heavy metal humus soil mobility leachability

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Frequency Analysis and Anti-Shock Mechanism of Woodpecker＇s Head Structure

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Journal of Bionic Engineering 2014年第2期11卷 282-287页

作者： Zhaodan zhu Chengwei wu Wei Zhang State Key Lab of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian 116024 P. R. China

The mechanical properties of the skull and the anti-shock characteristics of woodpecker＇s head were investigated by ex- periment and numerical simulation. We measured the micro-Young＇s modulus of the skull by nano-indentation method and calculated the macro-equivalent Young＇s modulus of the skull at different positions using homogenization theory. Based on the Computerized Tomography （CT） images of woodpecker head, we then built complete and symmetric finite element models of woodpecker＇s skull and its internal structure and performed modal analysis and stress spectrum analysis. The numerical results show that the application of pre-tension force to the hyoid bone can increase the natural frequency of woodpecker＇s head. The first natural frequency under the pre-tension force of 25 N reaches 57 Hz, which is increased by 21.3% from the non-pre-tension state and is more than twice the working frequency of woodpecker （20 Hz 25 Hz）. On the application of impact force to the tip of beak for 0.6 ms, high magnitudes of stress component occur at around 100 Hz and 8,000 Hz, far away from both the working frequencies and the natural frequencies of woodpecker head. The large gaps among the natural, working and stress response frequencies enable the woodpecker to effectively protect its brain from the resonance injury.

关键词： woodpecker anti-shock frequency modal analysis stress spectrum

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Asymptotic Ruin Probabilities of the Renewal Model with Constant Interest Force and Dependent Heavy-tailed Claims

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Acta Mathematicae Applicatae Sinica 2011年第2期27卷 329-338页

作者： Jin-zhu Li Rong wu School of Mathematical Sciences and LPMC Nankai University Tianjin 300071 China

In this paper, we investigate the asymptotic behavior for the finite- and infinite-time ruin probabilities of a nonstandard renewal model in which the claims are identically distributed but not necessarily inde- pendent. Under the assumptions that the identical distribution of the claims belongs to the class of extended regular variation （ERV） and that the tails of joint distributions of every two claims are negligible compared to the tails of their margins, we obtain the precise approximations for the finite- and infinite-time ruin probabilities.

关键词： asymptotic behavior extended regular variation negligible joint tails ruin probability

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Recent advances in visible-light-driven organic reactions

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National Science Review 2017年第3期4卷 359-380页

作者： Qiang Liu Li-zhu wu State Key Laboratory of Applied Organic Chemistry Lanzhou University Key Laboratory of Photochemical Conversion and Optoelectronic Materials Technical Institute of Physics and ChemistryChinese Academy of Sciences

In recent years, visible-light-driven organic reactions have been experiencing a significant renaissance in response to topical interest in environmentally friendly green chemical synthesis. The transformations using inexpensive, readily available visible-light sources have come to the forefront in organic chemistry as a powerful strategy for the activation of small molecules. In this review, we focus on recent advances in the development of visible-light-driven organic reactions, including aerobic oxidation, hydrogen-evolution reactions, energy-transfer reactions and asymmetric reactions. These key research topics represent a promising strategy towards the development of practical, scalable industrial processes with great environmental benefits.

关键词： visible light catalysis synthesis photocatalyst aerobic oxidation hydrogen evolution energy transfer asymmetric photoreaction

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A Survey of Newtonian Core-Shell Systems with Pseudo High Order Symplectic Integrator and Fast Lyapunov Indicator

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Chinese Journal of Astronomy and Astrophysics 2007年第4期7卷 601-610页

作者： Jun-Fang zhu Xin wu Da-zhu Ma Department of Physics Nanchang University Nanchang 330031

Newtonian core-shell systems, as limiting cases of relativistic core-shell models under the two conditions of weak field and slow motion, could account for massive circumstellar dust shells and rings around certain types of star remnants. Because this kind of systems have Hamiltonians that can be split into a main part and a small perturbing part, a good choice of the numerical tool is the pseudo 8th order symplectic integrator of Laskar ＆ Robutel, and, to match the symplectic calculations, a good choice of chaos indicator is the fast Lyapunov indicator （FLI） with two nearby trajectories proposed by wu, Huang ＆ Zhang. Numerical results show that the FLI is very powerful when describing not only the transition from regular motion to chaos but also the global structure of the phase space of the system.

关键词： celestial mechanics - chaos - methods: numerical

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Hyperbranched Polyurethane Acrylate Applied to UV Curable Flame Retardant Coatings

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Chemical Research in Chinese Universities 2001年第3期17卷 331-333页

作者： zhu Sheng-wu SHI Wen-Fang State Key Laboratory of Fire Science Department of Applied ChemistryUniversity of Science and Technology of ChinaHefei 230026P.R.China

UV curable hyperbranched prepolymers based on amine-ester, ester-amide and ether-amide started with AB_2-type monomers have been prepared by the authors. A series of work on allyl ether maleate hyperbranched polyesters for UV curing coatings by Hult and his colleagues has been reported. However, the UV cured films from those materials are all flammable when attached to fire without addition of flame retardants.

关键词： Flame retardant Polyurethane acrylate Phosphorus UV curing

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Cohomology of the Schrdinger Algebra S(1)

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Acta Mathematica Sinica,English Series 2014年第12期30卷 2054-2062页

作者： Yue zhu wu Xiao Qing YUE Lin Sheng zhu Department of Mathematics Changshu Institute of Technology Department of Mathematics Tongji University

We explicitly compute the first and second cohomology groups of the SchrSdinger algebra S（1） with coefficients in the trivial module and the finite-dimensional irreducible modules. We also show that the first and second cohomology groups of S（1） with coefficients in the universal enveloping algebras U（S（1））（under the adjoint action） are infinite dimensional.

关键词： Schrodinger algebra first cohomology groups second cohomology groups

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Quantum Size Effects on Two Electrons and Two Holes in Double-Layer Quantum Dots

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Communications in Theoretical Physics 2002年第7期38卷 99-102页

作者： XIE Wen-Fang zhu wu Department of Physics Guangzhou University Guangzhou 510405 China Department of Physics Guangzhou University Guangzhou 510405 China

We propose a procedure to solve exactly the Schrodinger equation for a system of two electrons and two holes in a double-layer quantum dot by using the method of few-body physics. The features of the low-lying spectra have been deduced based on symmetry. The binding energies of the ground state are obtained as a function of the electron-to-hole mass ratio σ for a few values of the quantum dot size.

关键词： two-electron and two-hole system, quantum dot, method of few-body physics

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