240 research outputs found

    Dissipation enhancement by transport noise for stochastic pp-Laplace equations

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    The stochastic pp-Laplace equation with multiplicative transport noise is studied on the torus Td (d≥2)\mathbb T^d\, (d\geq 2). It is shown that the dissipation is enhanced by transport noise in both the averaged sense and the pathwise sense.Comment: 20 pages. We have made some small correction

    Exponential Synchronization Analysis and Control for Discrete-Time Uncertain Delay Complex Networks with Stochastic Effects

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    The exponential synchronization for a class of discrete-time uncertain complex networks with stochastic effects and time delay is investigated by using the Lyapunov stability theory and discrete Halanay inequality. The uncertainty arises from the difference of the nodes’ reliability in the complex network. Through constructing an appropriate Lyapunov function and applying inequality technique, some synchronization criteria and two control methods are obtained to ensure the considered complex network being exponential synchronization. Finally, a numerical example is provided to show the effectiveness of our proposed methods

    Microfluidic flow direction and rate vector sensor based on a partially gold-coated TFBG

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    In microfluidic chips applications, the monitoring of the rate and the direction of a microfluidic flow is very important. Here, we demonstrate a liquid flow rate and a direction sensor using a partially gold-coated tilted fiber Bragg grating (TFBG) as the sensing element. Wavelength shifts and amplitude changes of the TFBG transmission resonances in the near infrared reveal the direction of the liquid flowing along the fiber axis in the vicinity of the TFBG due to a nanoscale gold layer over part of the TFBG. For a device length of 10 mm (and a diameter of 125 µm for easy insertion into microfluidic channels), the flow rates and the direction can be detectable unequivocally. The TFBG waveguiding properties allow such devices to function in liquids with refractive indices ranging from 1.33 to about 1.40. In addition, the proposed sensor can be made inherently temperature-insensitive by referencing all wavelengths to the wavelength of the core mode resonance of the grating, which is isolated from the fiber surroundings

    An investigation of 3.5 μm emission in Er3+-doped fluorozirconate glasses under 638 nm laser excitation

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    Intense 3.5 μm mid-infrared emission has been achieved in Er3+-doped ZBYA glasses, which is ascribed to the Er3+: 4F9/2→4I9/2 transition. Based on the absorption spectrum of Er3+ ions, a 638 nm laser was utilized to directly pump the upper level (Er3+: 4F9/2) to achieve 3.5 μm emission with enhanced quantum efficiency. Spectroscopic parameters were predicted by Judd-Ofelt theory. The maximum emission cross-section of the Er3+-doped ZBYA glass was estimated to be 5.5×10-22 cm2 at 3496 nm. Additionally, the fluorescence spectra and energy level lifetimes of ZBYA glass samples with different Er3+ ions doping concentrations were also measured. The theoretical and experimental results confirm the potential of Er3+-doped ZBYA glasses for use in the development of 3.5 μm mid-infrared fiber lasers

    A novel multilevel index model for distributed service repositories.

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    This study, based on the theory of equivalence relations, proposes a novel multilevel index model for decentralized service repositories to eliminate redundant information and enhance the time-management quality of the service retrieval process of the service repository architecture. An efficient resource discovery algorithm based on Discrete Hash Tables, is presented to enable efficient and effective retrieval services among different distributed repositories. The performance of the proposed model and the supporting algorithms have been evaluated in a distributed environment. Experimental results validate the effectiveness of our proposed indexing model and search algorithm.N/

    NH2+ implantations induced superior hemocompatibility of carbon nanotubes

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    NH(2)(+) implantation was performed on multiwalled carbon nanotubes (MWCNTs) prepared by chemical vapor deposition. The hemocompatibility of MWCNTs and NH(2)(+)-implanted MWCNTs was evaluated based on in vitro hemolysis, platelet adhesion, and kinetic-clotting tests. Compared with MWCNTs, NH(2)(+)-implanted MWCNTs displayed more perfect platelets and red blood cells in morphology, lower platelet adhesion rate, lower hemolytic rate, and longer kinetic blood-clotting time. NH(2)(+)-implanted MWCNTs with higher fluency of 1 × 10(16) ions/cm(2) led to the best thromboresistance, hence desired hemocompatibility. Fourier transfer infrared and X-ray photoelectron spectroscopy analyses showed that NH(2)(+) implantation caused the cleavage of some pendants and the formation of some new N-containing functional groups. These results were responsible for the enhanced hemocompatibility of NH(2)(+)-implanted MWCNTs

    Establishment and evaluation of a predictive model for length of hospital stay after total knee arthroplasty: A single-center retrospective study in China

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    BackgroundTotal knee arthroplasty (TKA) is the ultimate option for end-stage osteoarthritis, and the demand of this procedure are increasing every year. The length of hospital stay (LOS) greatly affects the overall cost of joint arthroplasty. The purpose of this study was to develop and validate a predictive model using perioperative data to estimate the risk of prolonged LOS in patients undergoing TKA.MethodsData for 694 patients after TKA collected retrospectively in our department were analyzed by logistic regression models. Multi-variable logistic regression modeling with forward stepwise elimination was used to determine reduced parameters and establish a prediction model. The discrimination efficacy, calibration efficacy, and clinical utility of the prediction model were evaluated.ResultsEight independent predictors were identified: non-medical insurance payment, Charlson Comorbidity Index (CCI) ≥ 3, body mass index (BMI) > 25.2, surgery on Monday, age > 67.5, postoperative complications, blood transfusion, and operation time > 120.5 min had a higher probability of hospitalization for ≥6 days. The model had good discrimination [area under the curve (AUC), 0.802 95% CI, 0.754–0.850]] and good calibration (p = 0.929). A decision curve analysis proved that the nomogram was clinically effective.ConclusionThis study identified risk factors for prolonged hospital stay in patients after TKA. It is important to recognize all the factors that affect hospital LOS to try to maximize the use of medical resources, optimize hospital LOS and ultimately optimize the care of our patients

    Comparative Study on Properties of Polylactic Acid Nanocomposites with Cellulose and Chitin Nanofibers Extracted from Different Raw Materials

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    Polylactic acid (PLA) was reinforced with ultralong cellulose and chitin nanofibers extracted from four raw materials by extrusion. The mechanical, rheological, thermal, and viscoelastic performances of four nanocomposites were comparatively studied in detail. The results showed that fibrillation of poplar was much easier than that of cotton, and fibrillation of crab shell was relatively hard as compared to prawn shell. The poplar CNFs/PLA composite exhibited the best mechanical properties among four nanocomposites due to the highest aspect ratio of nanofibers, while both the cotton CNFs/PLA composite and the crab shell CHNFs/PLA composite had low mechanical strength due to the relatively low aspect ratio. FE-SEM images showed that the ultralong nanofibers were uniformly dispersed in PLA matrix for all four samples with the water preblending method. The CTE values of the nanocomposites with 40 wt% nanofibers extracted from poplar, cotton, crab shell, and prawn shell were 69.5 × 10−6 K−1, 79.6 × 10−6 K−1, 77.2 × 10−6 K−1, and 75.3 × 10−6 K−1, respectively. All the results indicated that the aspect ratio of the nanofibers has a great influence on the performance of the composites, irrespective of the composites prepared by cellulose or chitin

    Ecological strategies of Hyphantria cunea (Lepidoptera: Arctiidae) response to different larval densities

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    Population density is an essential factor affecting the life history traits of insects and their trade-off relationships, as increasing density intensifies intraspecific competition. It decreases the average resources available to individuals within a population, affecting their morphology, physiology, behavior, and fitness. The fall webworm, Hyphantria cunea (Drury) (Lepidoptera: Arctiidae), has been an invasive pest of forest trees, ornamental plants, and fruit trees in China for many years. The larvae have a typical aggregation habit before the fourth instar and keep spitting silk to gather the damaged leaves into silk webs. However, the fitness of H. cunea in response to population density remains unclear. In this study, the critical biological parameters, food utilization, and population parameters of H. cunea in response to different rearing densities were investigated. The results showed that under high population density, H. cunea larvae showed better performance, with faster development, higher survival rates, and shorter generation time, but pupal weight and female fecundity decreased as population density increased. In contrast, for larvae raised in low density, the developmental period was prolonged, and mortality was increased, while higher food utilization, greater body size, and female fecundity were observed. Both males and females had similar development strategies in response to the density, but females may be more resistant to crowding than males. In conclusion, H. cunea could adopt different ecological strategies against the stress of density. High population densities result in shorter generation cycles and higher survival rates. Conversely, the low-density generation period becomes longer but with greater fecundity. The results may help determine the possible outbreak mechanism and develop effective population monitoring and forecasting measures for H. cunea
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