Wuhan Environmental Protection science Research Institute

Wuhan, China

Wuhan Environmental Protection science Research Institute

Wuhan, China
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Zhang W.,NUE | Wu X.,NUE | Cao W.,Wuhan Environmental Protection Science Research Institute
Advanced Materials Research | Year: 2011

Piezoelectric acoustic sensor with negative impedance matching circuit is put forward to enhance its sensitivity at low frequencies. The multi-physics problem coupled with sound wave equations, structure stress-strain equations, piezoelectric constitutive equations and electric ordinary equations is analyzed with FEM in detail. Frequency response characteristics are simulated when shunted with negative-capacitance, resistance in series. Sensitivity is obtained from 1kHz to 5kHz. When used proper electrical elements, the sensitivity of the piezoelectric sensor can even exceed that of no matching circuit over 2 factors in broad band. © (2011) Trans Tech Publications, Switzerland.


Zhang W.,NUE | Wu X.,NUE | Cao W.,Wuhan Environmental Protection Science Research Institute
Applied Mechanics and Materials | Year: 2012

Piezoelectric transducer with negative impedance matching circuit is put forward to enhance its performance in broadband frequencies. The typical multi-physics problem is coupled with sound wave equations, structure stress-strain equations, piezoelectric constitutive equations and electric ordinary equations, and it is analyzed with FEM in detail. Frequency response characteristics are simulated when shunted with negative-impedance in series. When proper negative synthesized elements are connected, the performance of low frequencies and bandwidth are enhanced obviously. © (2012) Trans Tech Publications, Switzerland.


Zhang W.,NUE | Wu X.,NUE | Cao W.,Wuhan Environmental Protection Science Research Institute
Advanced Materials Research | Year: 2011

Piezoelectric material shunted with negative capacitance can be used to insulate sound theoretically. But sound insulation of the system is limited by many factors. The dielectric and mechanical loss of the piezoelectric system deteriorate seriously the ability at some frequencies. According to the ideal electric elements formulas, the capacitance has imaginary part because of the loss. It has important influence on sound insulation ability. If a series resistance is introduced into the shunting circuit to form the imaginary part to compensate the loss, it is dependent on frequency. Sound insulation would be increased only in narrow band, and at some frequencies the system with the shunting circuit even becomes unstable. © 2011 Trans Tech Publications, Switzerland.


Liu C.,Wuhan Environmental Protection science Research Institute
Advanced Materials Research | Year: 2012

This paper presents a study of effects of low power ultrasonication on anaerobic digestion of sludge. Based on the optimizing tests, large lab scale experiments were implemented to investigate impact of different dosage of ultrasonication on a sludge anaerobic process. Hydrolysis capacity of sludge for protein, cellulose and fat, pH, content of coenzyme F420 and daily yield of biogas were detected to observe changes of the main biochemical steps. The underlying mechanisms for the enhancement of sludge digestion efficiency by low power ultrasonication are also discussed. © (2012) Trans Tech Publications, Switzerland.


Zhang W.,Wuhan Naval University of Engineering | Wu X.,Wuhan Naval University of Engineering | Cao W.,Wuhan Environmental Protection Science Research Institute
Proceedings of 2013 IEEE 11th International Conference on Electronic Measurement and Instruments, ICEMI 2013 | Year: 2013

A novel piezoelectric actuator is proposed to enhance its displacement in broad band at low frequencies. Its structure consists of a tunable stiffness part and a driven part. The tunable stiffness part is the piezoelectric stacks shunted with negative capacitance and its effective stiffness could be softening widely under the proper capacitance ratios at low frequencies. The principle of tunable stiffness system is analyzed and the proposed actuator is simulated by multi-physics coupled finite element method. When negative capacitance is selected properly, the displacement of the actuator can be increased up about 10 to 100 times in much broad band even at non-resonant low frequencies. The non-resonant actuator can be used to generate large displacement at low frequencies. © 2013 IEEE.


Zhang W.,Wuhan Naval University of Engineering | Wu X.,Wuhan Naval University of Engineering | Cao W.,Wuhan Environmental Protection Science Research Institute
Applied Mechanics and Materials | Year: 2011

Piezoelectric system shunted with proper negative capacitance in series has low dynamic stiffness. According to frequency characteristic equations of the piezoelectric system, optimal parameters and characteristics of both shunted series structures were deduced and compared theoretically. One is negative-capacitance and resistance in series, and the other is negative-capacitance, resistance and inductance in seires. It presented that high damping characteristic can be obtained at low frequencies when shunted with series negative-capacitance. If proper inductance is included in shunt circuit, effective bandwidth could be extended and the peak of amplitude of response is decreased, what' more, the stability of this structure is enhanced. This technology can be used in vibration isolators or sensors and the shunt structure including inductance is recommended. © (2011) Trans Tech Publications.


Sha Q.,Wuhan Environmental Protection science Research Institute | Huang J.,Wuhan Environmental Protection science Research Institute | Zhang W.,Wuhan University
Advanced Materials Research | Year: 2012

Sediments have a significant influence on the overlying water, and phosphorus (P) release from sediments is an important source for the lake eutrophication, particularly in shallow ones. To better understand the mechanisms of eutrophication, lakes impacted by urbanization at varying levels were investigated. The results showed TP increased continuously from the sediments of eutrophic lake, and released more with higher temperature. While phosphorous could process adsorption and desorption from sediments of mesotrophic lake. It suggested that the sediments of eutrophic lake could be the inner source of phosphorous. © (2012) Trans Tech Publications, Switzerland.


Zhu Z.,Wuhan Environmental Protection science Research Institute | Liu C.,Wuhan Environmental Protection science Research Institute | Deng D.,Wuhan University
Chinese Journal of Environmental Engineering | Year: 2014

Under different mixture reflux ratio (Ri) conditions, the performance of the modified A2O process was investigated. The COD removal rate (83.3%, 79.9% and 84.3% when Ri=200%, 300% and 200% respectively) was less influenced by Ri. However, the nitrogen removal rate was obviously influenced by it. The variation of the nitrate load and the actual hydraulic retention time for the anoxic pool caused by different Ri jointly made mutual restriction relations of the removal rate of TN and NH3-N. In addition, the nitrate served as the electron acceptor for the denitrifying phosphorus process. Its concentration was higher when Ri=200% and 300% (the corresponding TP average removal rate was as high as 73.3% and 85.3%, respectively). Moreover, the TP average removal rate was only 54.4% when relatively low nitrate concentration in the anoxic pool (Ri=400%). To cope with different inflow water quality, appropriate Ri can be chosen to coordinate the removal ability of TN, NH3-N and TP for the process. As a result, the denitrification and phosphorus removal efficiency can meet the request of higher effluent standard. ©, 2014, Science Press. All right reserved.


Xu W.,Wuhan Environmental Protection Science Research Institute | Li L.,Wuhan Environmental Protection Science Research Institute | Liu C.,Wuhan Environmental Protection Science Research Institute
Chinese Journal of Environmental Engineering | Year: 2014

Activated sludge sewage treatment is the most widely used method. We produced a set of automatic control aeration system which can be able to control the significant parameter of dissolved oxygen (DO) timely, accurately and stably, with the accuracy of ±0.2 mg/L. Applying this system is beneficial for improving the degree of automation of distributed rural sewage treating factories, which may effectively relieve the situation of the shortage of labor and the deficiency of operators' knowledge level and the instability of the treating result. Additionally, the redundancy of aeration could be greatly reduced as well as the expense of energy, which is benefit for decreasing the cost of functioning facilities for treating rural sewage in order to relieve the pressure of operation.


PubMed | Northwest Agriculture and Forestry University, CAS Institute of Earth Environment, Chinese Ministry of Water Resources and Wuhan Environmental Protection science Research Institute
Type: Journal Article | Journal: Environmental science. Processes & impacts | Year: 2016

A GIS approach and HJ-1B images were employed to determine the effect of landscape structure on aerosol optical depth (AOD) patterns. Landscape metrics, fractal analysis and contribution analysis were proposed to quantitatively illustrate the impact of land use on AOD patterns. The high correlation between the mean AOD and landscape metrics indicates that both the landscape composition and spatial structure affect the AOD pattern. Additionally, the fractal analysis demonstrated that the densities of built-up areas and bare land decreased from the high AOD centers to the outer boundary, but those of water and forest increased. These results reveal that the built-up area is the main positive contributor to air pollution, followed by bare land. Although bare land had a high AOD, it made a limited contribution to regional air pollution due to its small spatial extent. The contribution analysis further elucidated that built-up areas and bare land can increase air pollution more strongly in spring than in autumn, whereas forest and water have a completely opposite effect. Based on fractal and contribution analyses, the different effects of cropland are ascribed to the greater vegetation coverage from farming activity in spring than in autumn. The opposite effect of cropland on air pollution reveals that green coverage and human activity also influence AOD patterns. Given that serious concerns have been raised regarding the effects of built-up areas, bare land and agricultural air pollutant emissions, this study will add fundamental knowledge of the understanding of the key factors influencing urban air quality.

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