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Ma D.,Tianjin University | Zheng Q.,Tianjin University | Lin W.,Tianjin Municipal Engineering Design and Research Institute | Guo M.,Tianjin University
Aerosol Science and Technology | Year: 2017

Based on the theories of acoustic agglomeration and dust wet removal, an experimental apparatus was constructed to study the combined effects of acoustic agglomeration and atomization humidification in the pretreatment process to analyze the filtration performance of filter material. According to the concentration of coal-fired fly ash chosen in the experiments, the proper amount of atomization humidification and the proper sound pressure level (SPL) were determined. Under the relative humidity (RH) of 69% and with SPL in the range of 100 dB to 135 dB, the removal efficiency of fly-ash, the compressibility of the fly-ash particle layer on the filter media, and the performance of pulse filter cleaning were studied. The results indicate that the combined effects of sound fields and atomization humidification can effectively remove PM10 and PM2.5, and change the interaction and movement of particles, which can improve the pore structure of the fly-ash particle layer and increase the porosity of the dust layer. The results also indicate that with the proper amount of atomization humidification and appropriate SPL, the joint acoustic-atomization pretreatment can delay the filter material blocking, which reduces the pulse filter cleaning frequency and extends the filter cleaning cycle. It can also reduce the residual resistance after filter cleaning and prolong the operating lifetime of the filter media. © 2017 American Association for Aerosol Research © 2017 American Association for Aerosol Research

Cao J.,Tianjin Municipal Engineering Design and Research Institute | Liu Z.-C.,Tianjin Municipal Engineering Design and Research Institute | Feng X.-X.,Tianjin Municipal Engineering Design and Research Institute
Bridge Construction | Year: 2014

The calculation formulae for the overturning stability coefficients of the straight and curved bridges with box sections were deduced based on the mechanical principles in regard of the overturning stability problems of the bridges and with the aim of studying several overturning resistance checking calculation loads and the rationality of the loads commonly applied in the current design. The simplified formulae that were suitable for the design were proposed and were applied to the design of practical bridges. The results show that the application of the Highway-I Standard Load to the checking calculation of the overturning stability is slightly not sufficient and the densely arrayed 55 t heavy vehicles at spacing of 5 m should be preferably applied. The increase of the spacing between the support points of the connecting piers can increase the overturning stability of a straight bridge. With the gradual decrease of the curving radius of a curved bridge, the overturning stability coefficients of the bridge will gradually increase. The more curved the bridge is, the less easily the bridge will globally overturn. The overturning resistance capacity of the bridge with the gentle radius is the poorest, the second to the bridge is the straight bridge and the last is the bridge with the sharp radius.

Fan P.,Tianjin Municipal Engineering Design and Research Institute | Wang K.-L.,Tianjin Municipal Engineering Design and Research Institute
Forestry Studies in China | Year: 2011

Rooftop gardening or green roof establishment, one of the methods of afforestation for urban greening, has many benefits for the environment, the economy and urban landscapes. Various environmental stresses including heat, strong wind, sunshine and cold prevent most plants from growing well in extensive green roof systems. For the establishment of urban rooftop gardening in Beijing, we evaluated 13 ornamental plant species [Berberis thunbergii 'Atropurea Nana', Euonymus fortune (Turcz.) Hand., Viburnum dilatatum Thunb., Cotinus coggygria Scop., Swida alba Opiz., Weigela florida (Bunge.) A. DC., Jasminum nudiflorum Lindl., Euonymus japonicus Thunb., Euonymus japonicus 'Cuzhi', Buddleja davidii Franch., Pyracantha fortuneana (Maxim.) Li., Ligustrum lucidum Ait. and Spiraea salicifolia L.] for greening of flat rooftops. We obtained three indices concerning cold resistance, i. e., electrical conductivity of leaves, amounts of soluble sugars and amounts of free proline, providing a theoretical basis for selection of plants fit for roof and balcony greening. The results show that the six species P. fortuneana (Maxim.) Li., B. thunbergii 'Atropurea Nana', J. nudiflorum Lindl., E. fortune (Turcz.) Hand., E. japonicus Thunb. and E. japonicus 'Cuzhi' are excellent plants for rooftop gardening, judging from their strong ability in cold resistance. Plants such as L. lucidum Ait., C. coggygria Scop. and W. florida (Bunge) A. DC. showed a medium ability in cold resistance. However, these species can be used in roof and balcony greening after intensive management or acclimatization of variety. The ability to resist cold of plants such as W. florida (Bunge) A. DC., S. salicifolia L., V. rhytidophyllum and S. alba Opiz. (Cornus alba L.) was found to be rather weak. Therefore, cold-proof measures are recommended when using these species. © 2011 Beijing Forestry University and Springer-Verlag Berlin Heidelberg.

Ding H.,Tianjin University | Zhang Y.,Tianjin Municipal Engineering Design and Research Institute | Sun H.,Tianjin University | Feng L.,Tianjin University
Energy and Buildings | Year: 2016

To investigate the transfer characteristics of PM2.5 in a car cabin, several experiments were performed featuring real-time online monitoring of the concentration of PM2.5 and CO2 in the cabin under different ventilation modes (circulation with outdoor air and recirculation without outdoor air), at a minimum of mechanical ventilation and matching experimental route conditions. We analyzed the PM2.5 concentration distribution characteristics and the ratio of inside-to-outside PM2.5 concentration (I/O). The ventilation rate was determined by the CO2 concentration change during the experiments, and it was used to analyze the transfer characteristics of PM2.5. The results showed that under the "circulation with outdoor air" condition, the average I/O was 0.6, while it was 0.25 under the "recirculation" condition. I/O value decreased with acceleration of driving speed. It could be concluded that the ventilation mode has a significant impact on the concentration of PM2.5 in the cabin, and plays a decisive role in PM2.5 levels. The quantitative evaluation of PM2.5 transfer characteristics under the "circulation with outdoor air" condition showed that the contributions of ventilation, penetration, and deposition to the cabin PM2.5 concentration accounted for 69.3%, 22.8%, and 7.9%, respectively; while under the "recirculation" condition, penetration accounted for 72.0% and deposition accounted for 28.0%. © 2016 Elsevier B.V. All rights reserved.

Ji X.-B.,Northeastern University China | Zhao W.,Northeastern University China | Li S.-G.,Northeastern University China | Zhou Z.-S.,Tianjin Municipal Engineering Design and Research Institute
Dongbei Daxue Xuebao/Journal of Northeastern University | Year: 2013

The mechanical behavior and deformation of a metro tunnel using isolation piles adjacent to existing buildings with shallow foundation were studied with orthogonal finite element analysis method. Comparative analysis was implemented to examine: the settlement at the surface of existing building, the isolating effect of isolation piles and effectiveness of grouting on tunnel stability. Orthogonal finite element analysis was adopted to optimize three main parameters of isolation piles. The present results indicated that the existing building changes the shape of settlement trough and increases the inter-force and deformation. Isolation piles and grouting have some control on the deformation and inter-force of supporting structures. The optimal parameters of isolation piles are 33 m in length, 0.5 m in longitudinal spacing, and the distance between piles and tunnel is 1.5 m. This kind of optimization may provide references for the similar construction design.

Wang Z.,Tianjin University | He S.,Tianjin Municipal Engineering Design and Research Institute | Li J.,Tianjin Municipal Engineering Design and Research Institute | Song G.,China Tianchen Engineering Corporation
Advanced Materials Research | Year: 2012

Trilateral Flash Cycle (TFC) is particularly suitable for recovering energy from low-grade heat source. This paper presented a new mathematical model for calculating the performance of a twin screw expander integrated into a TFC working with organic components. The geometric parameters related to the rotation angle of male rotor e.g. groove volume, suction and discharge port area, leakage area etc were used in the model. The combination effects of internal leakage through five paths, oil injection, gas-oil heat transfer and refrigerant property were taken into account. The sensitivity of single parameter was also analyzed. To verify the model and the calculated p-φ indicator diagram, experimental recording of the diagram of twin screw expander was performed. The results of theoretical calculation were in good agreement with the experimental data, which indicated that the model in the present paper could be used as a powerful tool for performance prediction and product development.

Sun Y.,Tianjin University | Sun Y.,Pennsylvania State University | Wang Z.,Tianjin Municipal Engineering Design and Research Institute | Zhang Y.,Tianjin University | And 2 more authors.
PLoS ONE | Year: 2011

Objective: To test whether the incidence of common colds among college students in China is associated with ventilation rates and crowdedness in dormitories. Methods: In Phase I of the study, a cross-sectional study, 3712 students living in 1569 dorm rooms in 13 buildings responded to a questionnaire about incidence and duration of common colds in the previous 12 months. In Phase II, air temperature, relative humidity and CO 2 concentration were measured for 24 hours in 238 dorm rooms in 13 buildings, during both summer and winter. Out-to indoor air flow rates at night were calculated based on measured CO 2 concentrations. Results: In Phase I, 10% of college students reported an incidence of more than 6 common colds in the previous 12 months, and 15% reported that each infection usually lasted for more than 2 weeks. Students in 6-person dorm rooms were about 2 times as likely to have an incidence of common colds ≥6 times per year and a duration ≥2 weeks, compared to students in 3-person rooms. In Phase II, 90% of the measured dorm rooms had an out-to indoor air flow rate less than the Chinese standard of 8.3 L/s per person during the heating season. There was a dose-response relationship between out-to indoor air flow rate per person in dorm rooms and the proportion of occupants with annual common cold infections ≥6 times. A mean ventilation rate of 5 L/(s•person) in dorm buildings was associated with 5% of self reported common cold ≥6 times, compared to 35% at 1 L/(s•person). Conclusion: Crowded dormitories with low out-to indoor airflow rates are associated with more respiratory infections among college students. © 2011 Sun et al.

Yang H.,Tsinghua University | Xu W.,Tsinghua University | Zhang Q.,Tianjin Municipal Engineering Design and Research Institute
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2015

The strain localization in granular material due to its internal fabric under external load is a popular topic in the field of geotechnical engineering. However, current studies have focused on the analysis of statistical parameters, while the intrinsic link between the macroscopic phenomena and the mesoscopic mechanism has been ignored. The macroscopic and mesoscopic mechanical characteristics and the mechanism of deformation failure in the direct shear tests were systematically analyzed with the discrete element method(DEM). According to the development of shear stress ratio under the different normal stresses during the shearing process, anti-friction properties of granular material were discussed from the perspective of particle movement. A synchronic development between the anisotropic parameters of fabric and the macro-scale stress ratio was found. Through the statistical analysis of particle rotation, the friction between particles was revealed to be an important factor to maintain the relative stability of the mesoscopic structure. The morphological analysis of the networks of force chains revealed an agreement between the direction of principle stress and the principle direction of anisotropy. The decrease of the force chain intensity and the increase of porosity during the shearing tests were discovered. Two main mechanical models of force chain structures under different normal stresses were proposed. The fluctuation of macro-scale mechanical parameters was explained with the stability of system and the cumulative release of energy, showing the microscopic mechanism of deformation localization and dilatancy. ©, 2015, Academia Sinica. All right reserved.

Li H.,Tianjin Municipal Engineering Design and Research Institute | Wang X.,Tianjin Municipal Engineering Design and Research Institute | Shen K.,Tianjin Municipal Engineering Design and Research Institute
Tumu Gongcheng Xuebao/China Civil Engineering Journal | Year: 2011

The discussion is proposed that the influential depth of the vehicle load is unifiedly defined as 1.5 m. It should depend on the vehicle loads. Then, the definition of the heavy vehicle load and the working depth is established. The FEM based on the representative geological conditions, vehicle loads and the pavement in Tianjin Binhai New Area is developed. The working depthes of different vehicle loads are analyzed. The result indicates that the working depth of the standard vehicle load is 1.5 m, and that of the heavy vehicle load is 2.5 m.

Ma W.-S.,Tianjin Municipal Engineering Design and Research Institute
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2011

Based on the reconstruction project of Tianjin-Tanggu Expressway, the subgrade bearing capacity of composite foundation with pipe piles is calculated. The Terzaghi's theory is verified, and the Terzaghi's theoretical formula is modified for application in composite pipe piles. Through the analysis of the typical elements, the stress model of pile-soil under rigid foundation is derived. Finally, it is demonstrated that the results from this solution are in accordance with the design ones of a project. So the proposed method can reflect the working behaviors of foundation treatment of pipes pile in Tianjin area. It supplements the application of composite foundation with pipe piles and prospects for the model.

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