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Wireless sensor network is a data centric distributed self-organizing network. The transmission of data is the most important task of it. It is a topic worthy of study that how to ensure the reliability of data transmission in any environment .Fountain codes algorithm is simple, and has no ratio. It is very suitable for coding scheme for Wireless Sensor Networks. This paper mainly studies the Fountain codes of Raptor codes in wireless sensor network data transmission technology, and gives the concrete scheme and implementation ways. The application of this technology can improve the reliability of data transmission and transmission efficiency. It overcome the problems of very large packet error codec technology traditional rate and the decoding success rate.

Altium Desinger summer 09 is a circuit board design software with more perfect software function, quick operation and strong rationality. To make the beginner grasp the PCB design process well, this paper will describe the whole process and analyze every step with a circuit example

Permanent magnet synchronous motors(PMSM) as a representative of high efficiency motor was being used widely in the area of medium and small-sized power, high-accuracy,high reliability and wide-scope speed governing servo system.Otherwise,because traditional PI controller can not satisfy the high-performance of PMSM servo system,Fuzzy self-tuning PI(Fuzzy-PI) control method was used in this system, and proportion and integral parameter of PI controller is optimized by fuzzy logic.By simulation experiment, it was proved that Fuzzy-PI method had more steady and less q-axis current pulse to PI control in the transition procedure of PMSM governing.

Water cellar is an important facility to collect rainfall at the arid and semi-arid areas in China. The numerical simulation was carried out for one type of common cellar structure with concrete cellar wall, bottom floor and brick-arch roof using ABAQUS. Elastoplastic damage constitutive model was adopted to simulate the form and location of cellar cracking under different loads. Simulation results show that the circumferential cracks occures at the out side of the cellar bottom floor and the vertical cracks occures at the top of the cellar wall without water in cellar. In addition, vertical cracks also likely occures at the top of the cellar wall when full of water in cellar. Additional circle beam at the top of the cellar wall can reduce the principal tensile stress of the cellar wall and causing stress redistribution to uniform in the cross-section of cellar wall. Numerical analysis of the different locations of the reinforced concrete wall of water cellar shows that the additional circumferential steel bars at the top of the cellar wall are effective in reducing concrete cellar wall cracks.

This review addresses the introduction of fluorescent molecular tags into exo-enzymes and extra polymeric substances of bioaggregates and the use of confocal laser scanning microscopy (CLSM) to map their role, purpose and quantitative description of the biological processes they undertake. Multiple color staining coupled with CLSM and fluorescent in situ hybridisation (FISH) and flow cytometry have identified the individual polymeric substances, whether they are proteins, lipids, polysaccharides, nucleic acids or antibodies, as well as the microorganisms in the bioaggregate. Procedures are presented for simultaneous multicolor staining with seven different fluorochromes - SYTOX Blue for nucleic acids; Nile red for lipids; Calcofluor white [CW] for beta-polysaccharides; concanavalin A [Con A] for alpha-poly-saccharides; fluorescein-isothiocyanate [FITC] for proteins; SYTO 63 for live microbial cells and Calcium Green for monitoring calcium levels in the microbial cells. For the distribution of certain microbial strains, metabolic enzymes and extrapolymeric substances to be quantitatively described the generated colored images are converted into digital forms under specific predefined criteria. Procedures and computer software programs (Amira; MATLAB) are presented in order to quantitatively establish grid patterns from the CLSM images. The image is digitized using a threshholding algorithm followed by a reconstruction of the image as a volumetric grid for finite element simulation. The original color image is first converted to a grey followed by resizing, detection and modification of bilevel images and finally a total reversal of the image colors. The grid file is then used by specific computer software (Gambit, Fluent) for further numerical studies incorporating chemical reactions, transport processes and computational fluid dynamics including intra-bioaggregate fluid flow, and heat and mass transfer within the bioaggregate matrix.

This purpose of this investigation is to develop a new method for obtaining pore-size distribution (PSD) and other pore parameters from inner structure images. This method can be summarized into four key procedures to realize its functionality. A MATLAB program was composed to make the method applicable for image analysis. Image tests on wastewater biofouling layer samples showed the validity and feasibility of the method for analyzing intrinsic porous structures. The structural information obtained by this method can facilitate the understanding of transport phenomena, e.g., water flow and species diffusion inside porous structures.

The structure of fouling layer determines the pressure drop across the fouling layer. Three-dimensional distributions of nucleic acids, proteins, α- d -glucopyranose polysaccharides, β- d -glucopyranose polysaccharides and lipids in the biofouling layer that is formed on a mixed cellulose ester membrane were determined using a six-fold staining protocol combined with confocal laser scanning microscopy (CLSM). Based on the three-dimensional volumetric grid model of the fouling layer structure observed from the series of CLSM images, the intra-layer flow field during filtration was simulated using commercial software. The effective permeability of the fouling layer was estimated to be 2.65 × 10 −12 m 2 , which determines the upper estimate on the permeability of the fouling layer. The pores were categorized according to their diameters, using the maximum convex perimeter approach, and then the effects of the blocking pores on the permeability of the fouling layer were investigated. Blocking the large pores that accounted for 15% of the porosity reduced the mean permeability by 58%.

The dynamic performance of PEM fuel cell is one of the most important criteria in its design with application to mobile systems and portable devices. To analyze the features, this work employs an unsteady model about single phase transport in cathode side of PEM fuel cell with interdigitated flow field, which considers both convection and diffusion processes. Two types of dynamic performances, start-up and state-to-state operations, are analyzed. The effects of channel width fraction, porosity of the gas diffusion layer, pressure drop and the surface overpotential of the catalyst layer on the dynamic performance are investigated in detail. Predicted results found that the response time is generally quite fast, less than 0.1 s, to reach the 90% response. The time interval from the start-up to a steady state or from one steady state to another steady state mainly depends on the end condition.

 Th e fi n effi ciency of a fi nned oval tube heat exchanger is usually calculated by fi rst converting the oval tube to an equivalent round tube and then using the Schmidt fi n effi ciency technique. Th ere are two ways of selecting the equivalent round tube: one is to make the perimeter of the equivalent round tube equal to that of the oval tube; and the other is to make the area of the equivalent round tube equal to that of the oval tube. Th e present research uses the sector method to calculate the fi n effi ciency of fi nned oval tube exchangers. Th e fi n effi ciencies obtained from the equal-perimeter and equal-area methods were compared with those calculated from the sector method. Th e equal- perimeter method yields a higher fi n effi ciency, whereas the equal-area method gives a lower fi n effi ciency compared to the sector method. To make the Schmidt equation applicable to the oval tube case, correlations for determining the radius of the equivalent round tube were developed based on the results generated by the sector method. Correlations are provided for both staggered and in-line arrays of oval tubes. By combining the radius correlation with the Schmidt equation, one can readily determine the fi n effi ciency of a fi nned oval tube exchanger with accuracy comparable to that of the sector method.

We experimentally justified the validity of the basic assumption made in most floc models: there exists a strong advection flow through the floc. A swarm of bubbles were generated and released from the bottom of a water pool and rose at the same falling plane of the floc. Information regarding the fluid field, the capture ratio, and the extent of the advection flow were obtained by tracking the interactions of the floc and the bubbles. The advection flow through the floc is found unexceptionable in all tests. The polyelectrolyte flocculation would markedly reduce the extent of advection flow. The floc permeability was estimated based on comparison between experimental findings and the numerical simulations.

Amorphous silicon carbide nitride thin films were synthesized on single crystal silicon (0 0 1) substrates by rf reactive sputtered a silicon nitride target in methane and argon atmosphere. The effects of sputtering parameters such as target voltage in the range of 1.6‐3.0 kV on the optical properties were studied by a Cary 500 UN-VIS-NIR spectrophotometer and Bio-Rad FTS 185 FTIR spectrometer. The results showed that the deposition rate reached maximal at the target voltage of 2.5 kV. The refractive index, n, decrease with increase of target voltage except the sample deposited on 1.6 kV. Moreover, the maximal proportion of Si‐C and C‐N bond achieved at the target voltage of 2.5 and 2.0 kV, respectively. It reflects that the bonding configuration can be tailored by adjusting the target voltage. # 2001 Published by Elsevier Science B.V.

Two Hawaiian endemic yeast species, Metschnikowia hawaiiensis and Metschnikowia hamakuensis , were examined by means of multilocus characterization. In spite of their narrow range of distribution, restricted to the island of Hawai‘i, both species were found to be polymorphic at several loci. Alleles of different loci were distributed independently within local populations, confirming that sexual reproduction prevails among these facultatively asexual organisms. No alleles were shared across species, confirming their reproductive isolation. Although the sample size for the northern species, M. hamakuensis , is much less ( N = 7) than that for its southern relative, M. hawaiiensis ( N = 161), their genetic diversity is comparable. Genetic differentiation was detected in M. hawaiiensis populations at both regional (ca. 30–40 km) and local (ca. 1 km) scales. A single isolate recovered in a separate locality exhibited considerable allelic divergence from others, indicating that genetic isolation can occur over relatively short distances and suggesting a first step towards cessation of gene flow, which is required for speciation.

Postoperative cognitive dysfunction (POCD) is associated with cardiopulmonary bypass (CPB). We investigated the effect of different doses of inhaled sevoflurane administered prior to CPB on cerebral oxygen supply and demand, and the incidence of associated early POCD. One hundred and twenty patients were randomly allocated into four treatment groups (n = 30, each) and administered a high- [1.5 minimum alveolar concentration (MAC)], moderate- (1.0 MAC), low- (0.5 MAC), or no- sevoflurane dose prior to CPB. Standard blood gas parameters, serum S-100 protein, and neuron-specific enolase (NSE) were measured at different time points. The mini-mental state examination (MMSE) was administered 1 day before and 24 and 72 h after surgery. The jugular bulb venous oxygen saturation (SjvO2) in the moderate- and high-dose groups at a nasopharyngeal temperature of 25–28 °C was significantly higher compared with the control group, while the arteriovenous oxygen content difference (AVDO2) and cerebral extraction of oxygen (CEO2) were significantly reduced. The serum S-100 protein and NSE concentrations of the moderate- and high-dose groups at 1 and 6 h after the cessation of CPB were significantly lower than that of the control group. The 24 h postoperative MMSE scores of the moderate- and high-dose groups were significantly higher than those of the low-dose and control groups. An inhaled optimal concentration of sevoflurane may be beneficial for cerebral oxygen balance during CPB, and may ameliorate cognitive damage. However, the effect is dose-dependent.

This paper reviews briefly the definition of heat capacity and clarifies the defined specific heat capacity and volumetric heat capacity. The specific heat capacity and volumetric heat capacity, with our measured experimental data for CuO nanofluids, are discussed as an illustrating example. The result indicates that the specific heat capacity of CuO nanofluid decreases gradually with increasing volume concentration of nanoparticles. The measurement and the prediction from the thermal equilibrium model exhibit good agreement. The other simple mixing model fails to predict the specific heat capacity of CuO nanofluid. The nanoparticle size effect and solid-liquid interface effect on the specific heat capacity of nanofluid are discussed.

An investigation was conducted to understand flow boiling of de-ionized water in locally heated parallel microchannels. High speed visualization technology was employed to visually observe the transient phase change process in an individual microchannel. The process at locally heated condition was different from those at entirely heated condition where vapor column(s) stayed quasi-stable for a long time without venting out. Intensive interface oscillation occurred during phase change. Thin film evaporation appeared to be the main evaporation mode at the upstream vapor column cap, whereas nucleation happened occasionally at favorable flow, heat transfer and local wall conditions. Continuous condensation at the downstream vapor column cap led the flow back to single liquid phase regime out of the microchannel. A signal analysis method was introduced to study the interfacial oscillation behavior at the evaporating cap, which showed marked impact of the evaporation mode on the characteristic frequency.Copyright © 2008 by ASME

An experimental investigation was conducted to visually observe the transitional boiling in an individual water droplet on heated solid surfaces, with temperature ranging from 120°C to 160°C. Using a high-speed video imaging system, the dynamical process of the evaporation and boiling behavior of a droplet was recorded. Infrared ray temperature measurement technique was employed to investigate the instantaneous characteristics of heat transfer as the droplet was boiled. In the transition boiling regime, the phase change behavior of a droplet displayed a cyclical process. Restricted cyclical, sole-bubble cyclical and metastable cyclical styles were observed as the surface temperature increased.Copyright © 2007 by ASME

In present paper, a high speed CCD was employed to conduct a visualized observation of the phenomena of nucleation in micro capillary tubes covered with transparent metal film on the tube serving as the heater. When the heat flux reached a certain value, the liquid in capillary tubes was emitted instantaneously, which is referred as liquid exploding emission here, rather than generating visible bubbles. The critical heat flux and tube inner temperature corresponding to this phenomenon were measured to discuss the fundamental characteristics and physical significance of the phenomenon in different capillary tubes having different tube length, heating length and diameters.

An experimental investigation was conducted to visually observe the dynamical characteristics of water droplets with evaporation and nucleation on stainless steel and polished silicon surfaces. The water droplet diameter, contacting area and spreading speed were measured using a high-speed CCD camera at the surface temperature ranging from 110°C to 190°C. The spreading of water droplets under evaporation and nucleate boiling had a close relationship with the dynamic bubble behavior in the droplet as well as the surface properties. A model was proposed to describe the dynamical behavior of droplet spreading. Particularly, bubble volume, bubble interaction, surface temperature and surface properties had very strong influence on droplet spreading. Water droplets was easiest to spread at the surface temperature of 130 , and the spreading tendency increased with increasing surface coarseness. ℃

In this paper, liquid laminar flow friction in micro/mini ducts is considered for investigating the effects of roughness. The available research in this field is briefly reviewed, and the results are comprehensively discussed. The flow behavior is theoretically analyzed in the region adjacent to rough wall, and one of roughness effects is considered equivalent to the reduction of flow cross area, which is referred to the constricted flow model. A modified formula and coefficient η are introduced to correct the reduction value of hydraulic diameter. Two important factors, the space of two neighboring roughness elements and the reattachment length, are involved in accounting for the flow cross-section reduction. Eventually, an expression of flow resistance calculation is reduced in terms of relative roughness ε/d, parameter A and Reynolds number Re. Based on the ultimate friction factor formula, the influences of relative roughness ε/d, parameter A and Reynolds number Re on friction coefficient f are discussed by figuring and comparing f variation with those parameters.