3,031 research outputs found
Factors influencing Collaborative Communication in Virtual Teams
Collaborative communication has properties different from face to face communication. For instance team can generate ideas, manage information that are beyond the skills of any single team member. In this paper we examine factors that can influence collaborative communication in virtual teams. To study this we used a survey method across various organizations in China. We collected data to get responses from managers and experts engaged in collaborative efforts for product design developments in virtual environments. We conducted factor analysis and used the mean value of factors to test our hypothesis. We found that in the Chinese context, the significant factors were: constructs of team collaboration; information technology support and training; clear descriptions of team objectives and of tasks to be accomplished. Our results show that collaborative communication in collaborative virtual team environment is guided both by the global competition as well as indigenous and institutional pressures. Managers view decision making as a business issue in a globally competitive environment
An Improved Modeling for Low-grade Organic Rankine Cycle Coupled with Optimization Design of Radial-inflow Turbine
This document is the Accepted Manuscript of the following article: Lijing Zhai, Guoqiang Xu, Jie Wen, Yongkai Quan, Jian Fu, Hongwei Wu, and Tingting Li, ‘An improved modeling for low-grade organic Rankine cycle coupled with optimization design of radial-inflow turbine’, Energy Conversion and Management, Vol. 153: 60-70, December 2017. Under embargo. Embargo end date: 10 October 2018. The final, published version is available online at DOI: https://doi.org/10.1016/j.enconman.2017.09.063. Published by Elsevier Ltd.Organic Rankine cycle (ORC) has been proven to be an effective and promising technology to convert low-grade heat energy into power, attracting rapidly growing interest in recent years. As the key component of the ORC system, turbine significantly influences the overall cycle performance and its efficiency also varies with different working fluids as well as in different operating conditions. However, turbine efficiency is generally assumed to be constant in the conventional cycle design. Aiming at this issue, this paper couples the ORC system design with the radial-inflow turbine design to investigate the thermodynamic performance of the ORC system and the aerodynamic characteristics of radial-inflow turbine simultaneously. The constrained genetic algorithm (GA) is used to optimize the radial-inflow turbine with attention to six design parameters, including degree of reaction, velocity ratio, loading coefficient, flow coefficient, ratio of wheel diameter, and rotational speed. The influence of heat source outlet temperature on the performance of the radial-inflow turbine and the ORC system with constant mass flow rate of the heat source and constant heat source inlet temperature is investigated for four kinds of working fluids. The net electrical powers achieved are from few tens kWs to one hundred kWs. The results show that the turbine efficiency decreases with increasing heat source outlet temperature and that the decreasing rate of turbine efficiency becomes faster in the high temperature region. The optimized turbine efficiency varies from 88.06% (using pentane at the outlet temperature of 105 ºC) to 91.01% (using R245fa at the outlet temperature of 80 ºC), which appears much higher compared to common values reported in the literature. Furthermore, the cycle efficiency increases monotonously with the growth of the heat source outlet temperature, whereas the net power output has the opposite trend. R123 achieves the maximum cycle efficiency of 12.21% at the heat source outlet temperature of 110 ºC. Based on the optimized results, the recommended ranges of the key design parameters for ORC radial-inflow turbine are presented as well.Peer reviewe
A study on transmitted intensity of disturbance for air-spaced Glan-type polarizing prisms
We study theoretically and experimentally the transmission intensity of
polarized light through the air-spaced Glan-type polarizing prsims. It is found
that the variation of the transmitted intensity with the rotation angle
deviates from Malus Law, exhibiting a cyclic fluctuation with the rotation
angle. The occurrence of the disturbance is explained by the use of an argument
based on the interference effect produced from the air-gap in the prisms. The
theoretcal results are well agreed with the experimental ones. By selecting the
proper cut angle of prism and reducing the thickness of air-gap in prism, the
disturbance may be minimized.Comment: 5 pages, 10 figures, to be published in Optics Communication
Heat statistics in the relaxation process of the Edwards-Wilkinson elastic manifold
The stochastic thermodynamics of systems with a few degrees of freedom has
been studied extensively so far. We would like to extend the study to systems
with more degrees of freedom and even further-continuous fields with infinite
degrees of freedom. The simplest case for a continuous stochastic field is the
Edwards-Wilkinson elastic manifold. It is an exactly solvable model of which
the heat statistics in the relaxation process can be calculated analytically.
The cumulants require a cutoff spacing to avoid ultra-violet divergence. The
scaling behavior of the heat cumulants with time and the system size as well as
the large deviation rate function of the heat statistics in the large size
limit is obtained
Effect of Dihuang rougui decoction on ovariectomyinduced osteoporosis in rats
Purpose: To investigate the effect of Dihuang Rougui Decoction (DRD) on ovariectomy-induced osteoporosis in rats.Methods: Female Sprague-Dawley rats were randomly assigned to a normal group (control) and five ovariectomy (OVX) subgroups: OVX with vehicle (OVX), OVX with positive control drug (alendronate sodium tablets, 1.6 mg/kg/week), and OVX + DRD (75, 150 or 300 mg/kg/day). After the rats were subjected to ovariectomy for 4 weeks, fosamax or DRD were administered daily (orally) for 16 weeks. The bone mineral density (BMD) of the L4 vertebrae and right femurs of the rats was evaluated. Serum hormones estradiol (E2), follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels and serum alkaline phosphatase (ALP), osteocalcin (OC) and telopeptides of collagen type I (CTx) levels of the rats were determined. The bone tissue morphology of the rats was examined by microscopy.Results: The results show that DRD dose-dependently inhibited bone mineral density (BMD) reduction of L4 vertebrae and femurs (both p < 0.05). DRD significantly increased serum E2, FSH and LH levels (p < 0.05) in the osteoporotic rats, and significantly lowered serum ALP, CTx and OC concentrations, compared to OVX group (p < 0.01). Compared with OVX model group, bone trabeculae in all three DRD groups and nilestriol groups were wider, and the space and connections markedly increased. Furthermore, the medullary cavity reduced in size.Conclusion: These findings indicate that DRD mitigates OVX-induced osteoporosis in rats, and thus, the decoction has a potential for clinical management of osteoporosis patients.Keywords: Dihuang Rougui decoction, Osteoporosis, Ovariectomy, Bone mineral density, Serum bone marker, Bone tissue morpholog
Seroprevalence of Toxoplasma gondii infection in household and stray cats in Lanzhou, northwest China
<p>Abstract</p> <p>Background</p> <p><it>Toxoplasma gondii </it>is an important protozoan parasite infecting humans and almost all warm-blooded animals. As the only definitive host, cats play a crucial role in the transmission of <it>T. gondii </it>infection by shedding parasite oocysts in their feces. However, little information on <it>T. gondii </it>infection in cats was available in Lanzhou, northwest China. This study was performed to determine the seroprevalence of <it>T. gondii </it>infection in household and stray cats in Lanzhou, northwest China.</p> <p>Results</p> <p>A total of 221 (179 households and 42 strays) blood samples were collected from clinically healthy cats admitted to several pet hospitals located in Lanzhou City, between November 2010 and July 2011 for the serological detection of <it>T. gondii </it>infection. The majority (207) of these cats represented Chinese Lihua cats. 47 of 221 (21.3%) examined cats were seropositive for <it>T. gondii </it>infection using the modified agglutination test (MAT) at the cut-off of 1:25. The seroprevalence in household and stray cats was assessed to be 15.6% and 45.2%, respectively, and the difference was statistically significant (<it>P <</it>0.05). The seroprevalence ranged from 15.1% to 25.8% among different age groups, but the differences were not statistically significant (<it>P ></it>0.05). Studies showed that there was no relationship between seroprevalence and the gender (<it>P ></it>0.05).</p> <p>Conclusions</p> <p>The present survey indicated the high seroprevalence of <it>T. gondii </it>in cats in Lanzhou, northwest China, which poses a threat to animal and human health. Therefore, measures should be taken to control and prevent toxoplasmosis of cats in this area.</p
Vertical jetting induced by shear horizontal leaky surface acoustic wave on 36°Y-X LiTaO3
Shear horizontal surface acoustic waves (SH-SAWs) have been regarded as a good candidate for liquid sensing applications, but being inefficient in fluid manipulation due to a minimal fluid coupling between the fluid and acoustic waves. However, in this letter, a vertical jetting function was realized using the SH-SAW generated from a 36°Y-X LiTaO3 SAW device. The jetting of the droplet induced by the SH-SAWs was observed nearly along vertical direction, and the aspect ratio of the liquid beam is proportional to the applied power before breaking up, which is dramatically different from those generated from the conventional Rayleigh SAWs. By conducting theoretical simulation and experimental investigation on the SH-SAWs systematically, we concluded that the wave/energy pressure dissipated into the sessile droplets causes this vertical ejection on the device surface
Unifying constitutive law of vibroconvective turbulence in microgravity
The emergence of unified constitutive law is a hallmark of convective
turbulence, i.e., with in the classical
and in the ultimate regime, where the Nusselt number measures
the global heat transport and the Rayleigh number quantifies the strength
of thermal forcing. In recent years, vibroconvective flows have been attractive
due to its ability to drive flow instability and generate ``artificial
gravity'', which have potential to effective heat and mass transport in
microgravity. However, the existence of constitutive laws in vibroconvective
turbulence remains unclear. To address this issue, we carry out direct
numerical simulations in a wide range of frequencies and amplitudes, and report
that the heat transport exhibits a universal scaling law where is the vibration amplitude, is
the oscillational Reynolds number, and is the universal exponent. We
find that the dynamics of boundary layers plays an essential role in
vibroconvective heat transport, and the -scaling exponent is
determined by the competition between the thermal boundary layer (TBL) and
vibration-induced oscillating boundary layer (OBL). Then a physical model is
proposed to explain the change of scaling exponent from in the
OBL-dominant regime to in the TBL-dominant regime. We conclude
that vibroconvective turbulence in microgravity defines a distinct universality
class of convective turbulence. This work elucidates the emergence of universal
constitutive laws in vibroconvective turbulence, and opens up a new avenue for
generating a controllable effective heat transport under microgravity or even
microfluidic environment in which gravity is nearly absent.Comment: 18 pages, 3 figure
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