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- Zhang, Qing, et al.
(author)
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Prevalence of Otitis Media With Effusion Among Children in Xi'an, China : A Randomized Survey in China's Mainland
- 2011
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In: Annals of Otology, Rhinology and Laryngology. - : SAGE Publications. - 0003-4894 .- 1943-572X. ; 120:9, s. 617-621
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Journal article (peer-reviewed)abstract
- Objectives: We sought to identify the prevalence of otitis media with effusion (OME) in urban Chinese children in Xi'an, China. Methods: Five kindergartens and 3 primary schools were randomly selected in the urban area of Xi'an. Screening otoscopic and tympanometric examinations were performed on 2,902 children (1,491 boys and 1,411 girls) 2 to 8 years of age. Children with an abnormal tympanogram and simultaneous otomicroscopic signs of effusion were given a diagnosis of OME. Results: The overall prevalence of OME was 4.3%. By age group, the prevalence was 14.0% in 2-year-olds, 8.3% in 3-year-olds, 5.0% in 4-year-olds, 4.9% in 5-year-olds, 2.8% in 6-year-olds, 1.7% in 7-year-olds, and 3.2% in 8-year-olds. The prevalence rate for OME was 4.7% for boys versus 3.9% for girls, and 3.0% in the right ear versus 2.7% in the left, showing no statistically significant difference between genders or between ear sides (p > 0.05). Conclusions: The prevalence of OME in urban areas of Xi'an is not high in comparison with that of the same age group in surrounding areas.
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| 2. |
- Zhang, Qing, et al.
(author)
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A case of Meniere's disease in the left ear and Lermoyez syndrome in the right ear - a 32-month longitudinal observation and literature review
- 2010
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In: Acta Oto-Laryngologica. - : Informa UK Limited. - 0001-6489 .- 1651-2251. ; 130:9, s. 1084-1088
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Journal article (peer-reviewed)abstract
- We here present a 32-month follow-up of a case of Lermoyez syndrome combined with Meniere's disease. The patient was a 49-year-old male, with a stabilized severe hearing loss in the left ear for about 15 years after Meniere's disease. He started to show typical symptoms of Lermoyez syndrome in the right ear about 32 months ago. Audiologic data were obtained and imaging examinations were performed 0, 9, 15, 28, and 32 months after the onset of the Lermoyez syndrome. Pure tone threshold data obtained 5 months before the onset are also reported. The results show that the hearing thresholds, mainly at low frequencies, elevated rapidly during the first months shortly after the onset of the disease and slowly in later months. The glycerol test resulted in a remarkable hearing improvement at the beginning of the disease, but showed no detectable improvements as the disease advanced. Electrocochleogram revealed a -SP/AP value with click stimulus 0.65 at the 9th month and > 1.0 at the 28th month after the onset. Clinical manifestations of this patient fit well with a pathological endolymphatic hydrops.
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| 4. |
- Zhang, Xingxing, et al.
(author)
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Characterization of a solar photovoltaic/loop-heat-pipe heat pump water heating system
- 2013
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In: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 102, s. 1229-1245
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Journal article (peer-reviewed)abstract
- This paper introduced the concept, potential application and benefits relating to a novel solar photovoltaic/loop-heat-pipe (PV/LHP) heat pump system for hot water generation. On this basis, the paper reported the process and results of characterizing the performance of such a system, which was undertaken through dedicated thermo-fluid and energy balance analyses, computer model development and operation, and experimental verification and modification. The fundamental heat transfer, fluid flow and photovoltaic governing equations were applied to characterize the energy conversion and transfer processes occurring in each part and whole system layout; while the energy balance approach was utilized to enable inter-connection and resolution of the grouped equations. As a result, a dedicated computer model was developed and used to calculate the operational parameters, optimise the geometrical configurations and sizes, and recommend the appropriate operational condition relating to the system. Further, an experimental rig was constructed and utilized to acquire the relevant measurement data that thus enabled the parallel comparison between the simulation and experiment. It is concluded that the testing and modelling results are in good agreement, indicating that the model has the reasonable accuracy in predicting the system’s performance. Under the given experimental conditions, the electrical, thermal and overall efficiency of the PV/LHP module were around 10%, 40% and 50% respectively; whilst the system’s overall performance coefficient (COPPV/T) was 8.7. Impact of the operational parameters (i.e. solar radiation, air temperature, air velocity, heat-pump’s evaporation temperature, glazing covers, and number of the absorbing heat pipes) to the performance of the system (in terms of efficiencies of the PV/LHP module and the system’s overall performance coefficient COPPV/T) was investigated individually. The results indicated that lower solar radiation, lower air temperature, higher air velocity and smaller cover number led to enhanced electrical efficiency but reduced thermal efficiency of the module; whereas lower heat-pump’s evaporation temperature and larger number of heat absorbing pipes gave rise to both thermal and electrical efficiencies of the module. The research results would assist in developing a high efficient solar (space or hot water) heating system and thus contribute to realisation of the energy saving and associated carbon emission targets set for buildings globally.
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| 5. |
- Zhang, Xingxing, et al.
(author)
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Dynamic performance of a novel solar photovoltaic/loop-heat-pipe heat pump system
- 2014
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In: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 114, s. 335-352
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Journal article (peer-reviewed)abstract
- Objective of the paper is to present an investigation into the dynamic performance of a novel solar photovoltaic/loop-heat-pipe (PV/LHP) heat pump system for potential use in space heating or hot water generation. The methods used include theoretical computer simulation, experimental verification, analysis and comparison. The fundamental equations governing the transient processes of solar transmission, heat transfer, fluid flow and photovoltaic (PV) power generation were appropriately integrated to address the energy balances occurring in different parts of the system, e.g., glazing cover, PV cells, fin sheet, loop heat pipe, heat pump cycle and water tank. A dedicated computer model was developed to resolve the above grouping equations and consequently predict the system’s dynamic performance. An experimental rig was constructed and operated under the real weather conditions for over one week in Shanghai to evaluate the system living performance, which was undertaken by measurement of various operational parameters, e.g., solar radiation, photovoltaic power generation, temperatures and heat pump compressor consumption. On the basis of the first- (energetic) and second- (exergetic) thermodynamic laws, an overall evaluation approach was proposed and applied to conduct both quantitative and qualitative analysis of the PV/LHP module’s efficiency, which involved use of the basic thermal performance coefficient (COPth) and the advanced performance coefficient (COPPV/T) of such a system. Moreover, a simple comparison between the PV/LHP heat-pump system and conventional solar/air energy systems was conducted. The research results indicated that under the testing outdoor conditions, the mean daily electrical, thermal and overall energetic and exergetic efficiencies of the PV/LHP module were 9.13%, 39.25%, 48.37% and 15.02% respectively, and the average values of COPth and COPPV/T were 5.51 and 8.71. The PV/LHP module was found to achieve 3–5% higher solar exergetic efficiency than standard PV systems and about 7% higher overall solar energetic efficiency than the independent solar collector. Compared to the conventional solar/air heat pump systems, the PV/LHP heat pump system could achieve a COP figure that is around 1.5–4 times that for the conventional systems. It is concluded that the computer model is able to achieve a reasonable accuracy in predicting the system’s dynamic performance. The PV/LHP heat pump system is able to harvest significant amount of solar heat and electricity, thus enabling achieving enhanced solar thermal and electrical efficiencies. All these indicate a positive implication that the proposed system has potential to be developed into a high performance PV/T technology that can contribute to significant fossil fuel energy saving and carbon emission.
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| 6. |
- Zhang, Xingxing, et al.
(author)
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Review of R&D progress and practical application of the solar photovoltaic/thermal (PV/T) technologies
- 2012
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In: Renewable & sustainable energy reviews. - : Elsevier BV. - 1364-0321 .- 1879-0690. ; 16:1, s. 599-617
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Journal article (peer-reviewed)abstract
- In this paper, the global market potential of solar thermal, photovoltaic (PV) and combined photovoltaic/thermal (PV/T) technologies in current time and near future was discussed. The concept of the PV/T and the theory behind the PV/T operation were briefly introduced, and standards for evaluating technical, economic and environmental performance of the PV/T systems were addressed. A comprehensive literature review into R&D works and practical application of the PV/T technology was illustrated and the review results were critically analysed in terms of PV/T type and research methodology used. The major features, current status, research focuses and existing difficulties/barriers related to the various types of PV/T were identified. The research methods, including theoretical analyses and computer simulation, experimental and combined experimental/theoretical investigation, demonstration and feasibility study, as well as economic and environmental analyses, applied into the PV/T technology were individually discussed, and the achievement and problems remaining in each research method category were described. Finally, opportunities for further work to carry on PV/T study were identified. The review research indicated that air/water-based PV/T systems are the commonly used technologies but their thermal removal effectiveness is lower. Refrigerant/heat-pipe-based PV/Ts, although still in research/laboratory stage, could achieve much higher solar conversion efficiencies over the air/water-based systems. However, these systems were found a few technical challenges in practice which require further resolutions. The review research suggested that further works could be undertaken to (1) develop new feasible, economic and energy efficient PV/T systems; (2) optimise the structural/geometrical configurations of the existing PV/T systems; (3) study long term dynamic performance of the PV/T systems; (4) demonstrate the PV/T systems in real buildings and conduct the feasibility study; and (5) carry on advanced economic and environmental analyses. This review research helps finding the questions remaining in PV/T technology, identify new research topics/directions to further improve the performance of the PV/T, remove the barriers in PV/T practical application, establish the standards/regulations related to PV/T design and installation, and promote its market penetration throughout the world.
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