8,275 research outputs found
Optical guidelines and signal quality for LDA applications in circular pipes
The optical performance of laser Doppler anemometer (LDA) technology in applications to circular pipes with an external plane wall has been clarified and quantified. It is shown that optical aberration is a persistent feature in such LDA measurements and measurements from each direction along a full pipe diameter are needed to obtain the flow distribution. For measurements of axial velocities in a circular pipe no special care has to be taken, even if the optical plane deviates from the pipe axis. For measurements of tangential and radial velocities detailed operating guidelines have been presented with respect to the shift of the measurement volume, its optical properties and the beam waist dislocations. The analysis reveals the possible influences on both the signal quality and the measurement accurac
Dissipation function of the first-order phase transformation in VO2 ceramics by internal-friction measurements
In order to apply the concept of the dissipation function during the first-order phase transition (FOPT) in solids, we measured the internal friction Q-1 and shear modulus μ for a range of frequencies of polycrystalline ceramics VO2 as the sample passed through a FOPT across the temperature range of 300–420 K. The experiment was repeated for different temperature variation rate Ṫ. We have found that for each frequency, a maximum of Q-1 and a minimum of μ occurred at the same temperature Tp when Ṫ was kept constant. The numerical values of the dissipation function ΔGR plus other FOPT parameters have been deduced using Q-1 data. The general trend of ΔGR-T and other results are found to be consistent with known physical aspects.published_or_final_versio
Virtual Teamwork Environment -A Web-Based Conical Administration Framework for MNC
Because today\u27s commerce is information intensive and requires sophisticated computer support, it is difficult for the traditional corporations working individually to adapt the new environment to utilize information and build multinational teams effectively and efficiently. The need for global competitiveness makes multinational corporation (MNC) shift to a new team style: virtual teams, which are groups of individuals collaborating in the execution of a specific project while located at multiple individual sites or multiple group sites [1]. The environment of a virtual team is a cyberspace in which virtual project groups communicate mutually. In this paper, we focus on the functionality and structure of this highly abstract system. The groupware available for the teamwork collaboration is briefly introduced. A web-based teamwork environment served for MNC is thenpresented. We present a conical management architecture combined with a network topology: a peers and client/server mode instead of the traditional client/server and pure peers mode. It provides an orderly teamwork environment to replace the crowed and chaos-like teamwork space used currently. A design and implementation of the framework is finally described based on Sun Microsystems\u27 Java languag
Response of innate immune factors in abalone Haliotis diversicolor supertexta to pathogenic or nonpathogenic infection
Cell free hemolymph from Haliotis diversicolor supertexta was prepared from fluid collected at 1, 4, 8. 12. 24, 48 96 It after injection with either Escherichia coli, Vibrio parahaemolyticus or 0.9 NaCl solution (control group). The response of selected innate immune parameters (lysozyme, antibacterial activity, alkaline phosphatase, acid phosphatase, phenoloxidase, and superoxide dismutase) was investigated. Results showed that the activities of ACP (Acid Phosphatase) from abalone injected with V. parahaemolyticus were much higher than that of the control group at 24 h after injection. The ALP (Alkaline Phosphatase) activities of abalone challenged with V. parahaemolyticus were significantly higher than those of the control group at 8 h and increased further up to 48 h after the challenge. In contrast, the activities of ALP and ACP in the E. coli-challenged group showed no statistically significant differences at any of the sampling times. The activities of SOD (Superoxide Dismutase) in cell free hemolymph from the V. parahaemolyticus-exposed group were significantly lower than those of the control group at both I h and 24 h, whereas there was no difference in SOD activity observed in the group exposed to E. coli at any of the sampling times. The activities of lysozyme and phenoloxidase in Haliotis diversicolor were relatively low in both control and bacteria-ex posed groups when compared with reports for other invertebrates no significant difference was found between the infected groups and the control for these two parameters, due to the low activities and high individual variance
Giant radiation heat transfer through the micron gaps
Near-field heat transfer between two closely spaced radiating media can
exceed in orders radiation through the interface of a single black body. This
effect is caused by exponentially decaying (evanescent) waves which form the
photon tunnel between two transparent boundaries. However, in the mid-infrared
range it holds when the gap between two media is as small as few tens of
nanometers. We propose a new paradigm of the radiation heat transfer which
makes possible the strong photon tunneling for micron thick gaps. For it the
air gap between two media should be modified, so that evanescent waves are
transformed inside it into propagating ones. This modification is achievable
using a metamaterial so that the direct thermal conductance through the
metamaterial is practically absent and the photovoltaic conversion of the
transferred heat is not altered by the metamaterial.Comment: 4 pages, 3 figure
Novel critical point drying (CPD) based preparation and transmission electron microscopy (TEM) imaging of protein specific molecularly imprinted polymers (HydroMIPs)
We report the transmission electron microscopy (TEM) imaging of a hydrogel-based molecularly imprinted polymer (HydroMIP) specific to the template molecule bovine haemoglobin (BHb). A novel critical point drying based sample preparation technique was employed to prepare the molecularly imprinted polymer (MIP) samples in a manner that would facilitate the use of TEM to image the imprinted cavities, and provide an appropriate degree of both magnification and resolution to image polymer architecture in the <10 nm range. For the first time, polymer structure has been detailed that clearly displays molecularly imprinted cavities, ranging from 5-50 nm in size, that correlate (in terms of size) with the protein molecule employed as the imprinting template. The modified critical point drying sample preparation technique used may potentially play a key role in the imaging of all molecularly imprinted polymers, particularly those prepared in the aqueous phase
Master equation, design equations and runaway speed of the Kaplan turbine
To make the Kaplan turbine technology comparable to both the Pelton and the Francis turbine, the master equation for the Kaplan turbine has been established by analyses similar to that for the Francis turbine. The analysis begins with the descriptions of free vortex flows at the runner inlet and the swirl flow at the impeller exit. By considering the Euler equation for specific work and by further evaluating the most significant shock and swirling losses, the first and the second energy equations in the form of hydraulic efficiency were formulated. The master equation is then established by combining both energy equations. In addition, three design equations and a new design parameter are presented. The master equation relates the turbine hydromechanics to the geometrical design of both the runner and the guide-vane parameters. It enables the complete hydraulic characteristics of a given Kaplan turbine to be analytically and simply computed. A computation example demonstrates the functionality and applicability of the method. With the reconstructed master equation, the runaway speed of the Kaplan turbine and its dependence on the guide-vane setting can be easily and precisely computed. For bulb turbines with guide vanes directly ahead of the turbine runner in the same tube, all computations are also applicable using another equivalent control parameter
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