813 research outputs found

    Statistical analyses on multi-scale features of monitoring data from health monitoring system in long cable supported bridges

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    AbstractStrain-time histories and other data acquired from a structural health monitoring system (SHMS) installed on a bridge reflect the real-time structural response of the bridge under actual service and environmental loading. It is necessary to understand the inherent features of the data if we want to have confidence in using them to assess the health state or detect potential damage in the structure. This paper aims at exploring the inherent features of strain-time histories data from SHMS in order to find out their behavior in multiple temporal scales and to obtain reliable, clean and normalized data at the dominant scale of stresses inducing fatigue. Firstly, the strain history data from SHMS installed on Runyang Yangtze Bridges (RYB) were analyzed within three typical temporal scales to explore their different characteristics and their own cut-off frequency which span different orders of magnitude. Then, based on the description of the multi-scale features of the monitored data, a further investigation of the dominant scale controlling fatigue failures was carried out. The result shows that, the strain data corresponding to the typical temporal scales of 106, 103 and 100 sec are caused by temperature change, with cut-off frequency fc,1 in the 10−2 Hz range, by train load, with fc,2 in the 10−1 Hz range and by truck load, with fc,3 in the 100 Hz range. Noise shows significant coupling effect when coarse scale strain data are used for the evaluation, which may lead to significant error even it is in small level acceptable in engineering analyses

    Distribution of power requirements during yarn winding in ring spinning

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    A model of a yam package is established for a ring spinning system. The yarn layer, surface area, and mass of the yam package are formulated with respect to the diameters of the empty bobbin and full yarn package, yarn count, and yarn winding-on time. Based on the principles of dynamics and aerodynamics, models of the power requirements for overcoming the skin friction drag, increasing the kinetic energy of the yarn package (bobbin and wound yarn), and overcoming the yarn wind-on tension are developed. The skin friction coefficient on the surface of a rotating yam package is obtained from experiment. The power distribution during yam packaging is discussed based on a case study. The results indicate that overcoming the skin friction drag during yarn winding consumes the largest amount of energy. The energy required to overcome the yarn wind-on tension is also significant

    Kir5.1 regulates Nedd4-2-mediated ubiquitination of Kir4.1 in distal nephron.

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    Kir4.1/5.1 heterotetramer participates in generating the negative cell membrane potential in distal convoluted tubule (DCT) and plays a critical role in determining the activity of Na-Cl cotransporter (NCC). Kir5.1 contains a phosphothreonine motif at its COOH terminus (AA249-252). Coimmunoprecipitation showed that Nedd4-2 was associated with Kir5.1 in HEK293 cells cotransfected with Kir5.1 or Kir4.1/Kir5.1. GST pull-down further confirmed the association between Nedd4-2 and Kir5.1. Ubiquitination assay showed that Nedd4-2 increased the ubiquitination of Kir4.1/Kir5.1 heterotetramer in the cells cotransfected with Kir4.1/Kir5.1, but it has no effect on Kir4.1 or Kir5.1 alone. Patch-clamp and Western blot also demonstrated that coexpression of Nedd4-2 but not Nedd4-1 decreased K currents and Kir4.1 expression in the cells cotransfected with Kir4.1 and Kir5.1. In contrast, Nedd4-2 fails to inhibit Kir4.1 in the absence of Kir5.1 or in the cells transfected with the inactivated form of Nedd4-2 (Nedd4-2C821A). Moreover, the mutation of TPVT motif in the COOH terminus of Kir5.1 largely abolished the association of Nedd4-2 with Kir5.1 and abolished the inhibitory effect of Nedd4-2 on K currents in HEK293 cells transfected with Kir4.1 and Kir5.1 mutant (Kir5.1T249A). Finally, the basolateral K conductance in the DCT and Kir4.1 expression is significantly increased in the kidney-specific Nedd4-2 knockout or in Kir5.1 knockout mice in comparison to their corresponding wild-type littermates. We conclude that Nedd4-2 binds to Kir5.1 at the phosphothreonine motif of the COOH terminus, and the association of Nedd4-2 with Kir5.1 facilitates the ubiquitination of Kir4.1, thereby regulating its plasma expression in the DCT

    Quantum secure communication scheme with W state

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    Recently, Cao et al. proposed a new quantum secure direct communication scheme using W state. In their scheme, the error rate introduced by an eavesdropper who takes intercept-resend attack, is only 8.3%. Actually, their scheme is just a quantum key distribution scheme because the communication parties first create a shared key and then encrypt the secret message using one-time pad. We then present a quantum secure communication scheme using three-qubit W state. In our scheme, the error rate is raised to 25% and it is not necessary for the present scheme to use alternative measurement or Bell basis measurement. We also show our scheme is unconditionally secure.Comment: Comments are welcom

    Characteristics and Sensing Properties of the La1-xNdxCo0.3Fe0.7O3 System for CO Gas Sensors

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    A series of nanostructured La1-xNdxCo0.3Fe0.7O3 perovskite-type (x ranging from 0 to 1) were prepared using the co-precipitation method. CO gas sensing properties of La1-xNdxCo0.3Fe0.7O3 sensors were performed. La0.7Nd0.3Co0.3Fe0.7O3 sensor showed the highest response at 250 °C (S=52.8)

    Understory plant diversity assessment of Szemao pine (Pinus kesiya var. langbianensis) plantations in Yunnan, China

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    Evaluación de la diversidad de plantas de sotobosque en plantaciones de pino Szemao (Pinus kesiya var. langbianensis) en Yunnan, China.— La sostenibilidad es un objetivo clave para la gestión tanto de bosques naturales como de plantaciones, mientras que los estudios sobre biodiversidad constituyen herramientas muy útiles para mejorar la conservación de especies amenazadas. El pino Szemao (Pinus kesiya var. langbianensis) es un árbol nativo de China que se usa en plantaciones. Este estudio evalúa la diversidad del sotobosque en plantaciones de pino Szemao (SP) y otros tipos de vegetación local, como bosques secundarios perennifolios (SE) y tierras de cultivo abandonadas (AF), en la provincia de Yunnan, China. El muestreo se realizó en tres rangos altitudinales, y se evaluó riqueza y cobertura de hierbas y arbustos además de factores ambientales. En general, la riqueza promedio y la diversidad de Shannon-Wiener fueron mayores en SE que en SP, y a su vez que en AF, mientras que la equitatividad tendió a ser mayor en SP. Asimismo, dichos índices tendieron a aumentar con la altitud en SP y AF, aunque en SE fueron mayores a altitudes bajas y medias. La inclusión de factores ambientales resaltó las diferencias entre rangos altitudinales, siendo el contenido de agua (en el estrato herbáceo) y el tipo de suelo (en el estrato arbustivo) las variables más significativas. Las plantaciones de pino Szemao en Yunnan afectan al sotobosque, encontrándose pocas especies raras o amenazadas en su interior. Las reservas naturales y los trasplantes podrían ser una alternativa para proteger a las especies amenazadas si se llevan a cabo anticipadamente a las plantaciones.Sustainability is a key objective for managers of both natural forests and plantations, and biodiversity assessments are important tools to improve conservation of endangered species. Szemao pine (Pinus kesiya var. langbianensis) is a native Chinese tree species used in plantations. This study evaluated differences in understory diversity among Szemao pine plantations (SP) and other local current vegetation types: secondary evergreen forests (SE) and abandoned farmlands (AF) in Yunnan Province. Sampling was performed at three elevation ranges, where species richness, species cover, and environmental variables in the herb and shrub layers were measured. We found that indexes for average richness and Shannon?Wiener diversity were higher in SE than in SP, which were in turn higher than in AF, while the index for evenness was higher in SP. These indexes increased with elevation in SP and AF, but were higher at low and medium elevations in SE. Inclusion of environmental factors highlighted elevation differences, with water content (at herb layer) and soil type (at shrub layer) being the most significant variables. In conclusion, plantations of Szemao pine negatively affect understory diversity in Yunnan, and furthermore, only a few rare or threatened species could be found in the plantations. Nature reserves and transplanting could protect threatened species if established before plantations.Fil: Wang, H.F.. Research Center for Eco-Environmental Sciences; ChinaFil: Lencinas, María Vanessa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Ross Friedman, Cynthia. Thompson Rivers University.; CanadáFil: Zhu, Z.X.. Institute of Botany. Chinese Academy of Sciences; ChinaFil: Qiu, J. Research Center for Eco-Environmental Sciences; Chin

    Adsorption properties of several materials for solar adsorption cooling system

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    Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.It is important for an adsorption refrigeration system to use an appropriate adsorption material and the matched refrigerant. In the present study, the adsorption characteristic of the allochroic silica gel and three kinds of zeolite material to water-vapor have been investigated experimentally. Upon analyzing the variation of the material adsorption capacity exposed in moist air atmosphere of controlled temperature and humidity, the adsorption characteristic to water-vapor is verified, and the influence of the temperature and the pressure are correlated. The results show that the dynamic adsorption characteristic and the adsorption isotherm of the tested material is closely related to its microstructure such as the BET surface area, the distribution of the pore diameter, the porosity, and the bulk density, etc. In view of the application in the solar adsorption air conditioning, 5A-II and 13X-II zeolite shows relatively fast adsorption rate and their time to adsorption saturation state is short. The allochroic silica gel, 5A-II and 13X-II zeolite is of higher adsorption capacity, while the dynamic adsorption characteristic of 5A-I and ZSM-5 zeolite is more sensitive to the change of pressure. The adsorption isotherm of allochroic silica gel follows an exponential function and ZSM-5 and 5A-I zeolites shows a “S" curve, The latter may be more suitable for the solar adsorption cooling system in summer.cf201

    Acoustic phonon transport through a double-bend quantum waveguide

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    In this work, using the scattering matrix method, we have investigated the transmission coefficients and the thermal conductivity in a double-bend waveguide structure. The transmission coefficients show strong resonances due to the scattering in the midsection of a double-bend structure; the positions and the widths of the resonance peaks are determined by the dimensions of the midsection of the structure. And the scattering in the double-bend structure makes the thermal conductivity decreases with the increasing of the temperature first, then increases after reaches a minimum. Furthermore, the investigations of the multiple double-bend structures indicate that the first additional double-bend structure suppresses the transmission coefficient and the frequency gap formed; and the additional double-bend structures determine the numbers of the resonance peaks at the frequency just above the gap region. These results could be useful for the design of phonon devices.Comment: 13 pages, 6 figures, elsart.cls is use

    Multiple superconducting gap and anisotropic spin fluctuations in iron arsenides: Comparison with nickel analog

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    We present extensive 75As NMR and NQR data on the superconducting arsenides PrFeAs0.89F0.11 (Tc=45 K), LaFeAsO0.92F0.08 (Tc=27 K), LiFeAs (Tc = 17 K) and Ba0.72K0.28Fe2As2 (Tc = 31.5 K) single crystal, and compare with the nickel analog LaNiAsO0.9F0.1 (Tc=4.0 K) . In contrast to LaNiAsO0.9F0.1 where the superconducting gap is shown to be isotropic, the spin lattice relaxation rate 1/T1 in the Fe-arsenides decreases below Tc with no coherence peak and shows a step-wise variation at low temperatures. The Knight shift decreases below Tc and shows a step-wise T variation as well. These results indicate spinsinglet superconductivity with multiple gaps in the Fe-arsenides. The Fe antiferromagnetic spin fluctuations are anisotropic and weaker compared to underdoped copper-oxides or cobalt-oxide superconductors, while there is no significant electron correlations in LaNiAsO0.9F0.1. We will discuss the implications of these results and highlight the importance of the Fermi surface topology.Comment: 6 pages, 11 figure
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