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Zhu H.,Zhejiang University City College
Science China Information Sciences | Year: 2017

In this paper, an efficient construction of multicast key distribution schemes based on semantically secure symmetric-key encryption schemes and cryptographically strong pseudo-random number generators is presented and analyzed. The proposed scheme is provably secure against adaptive adversaries leveraging the security amplification technique defined over the logical key hierarchy structures. Our protocol tolerates any coalition of revoked users; in particular, we do not assume any limit on the size or structure of the coalition. The proposed scheme is efficient as a performance of Join or Leave procedure requires 2 log(N) multicast activities defined over a sibling ancestor node set, 2 log(N) internal state updates of the underlying pseudo-random number generator and 2 log(N) symmetric-key encryption activities for N users in a session. © 2016, Science China Press and Springer-Verlag Berlin Heidelberg.

Wu H.,Yiwu Industrial and Commercial College | Wei G.,Zhejiang University City College
Modern Tunnelling Technology | Year: 2014

This paper presents that the curve of soil settlement induced by small-interval double-bore parallel shield tunnel construction conforms with the normal distribution, and summarizes the calculation method for surface settlement. Aiming at the deficiencies of various calculation methods, the modified 2D Peck formula is established to calculate the deep soil settlement while considering the asymmetry of the settlement curve. Based on the research of calculation parameters, the measured results show that iTotal/iAdvancing tunnel (i: width coefficient of the settlement trough) decreases linearly with the increase of h/D, thus giving the formula for iTotal and ηTotal (η: Soil loss rate). Additionally, this paper firstly proposes the coefficient C of relative horizontal distance between two tunnel axes (C<0.6; C=L/(h+R)), to which the shape of the total ground settlement curve is related. According to the case study, the predicted values agree with the measured ones and the calculation is relatively simple.

Wei G.,Zhejiang University City College | Li G.,Zhejiang University | Su Q.,Zhejiang University
Modern Tunnelling Technology | Year: 2014

An underground passage passes over the existing shield-driven tunnel of the Hangzhou Metro line 1. Due to the complex geological conditions and surrounding environment of the over -passing section, tunnel deformation has to be strictly controlled. For this reason, control measures like foundation reinforcement and sectional excavation are considered in the tunnel design. Based on the monitoring data from the pile foundation construction and foundation pit excavation, this paper analyzes the rules and characteristics of the vertical displacement, horizontal displacement, and convergence of the shield -driven tunnel at different construction stages. The results show that the pile foundation construction may cause vertical settlement of the tunnel (maximum: 5mm), but has little influence on the horizontal convergence; additionally, foundation pit excavation may cause tunnel floating (maximum: 5mm) and horizontal radial convergence, but has little influence on the horizontal displacement.

Zhang Y.,Zhejiang University City College
Zhejiang da xue xue bao. Yi xue ban = Journal of Zhejiang University. Medical sciences | Year: 2013

To prepare nanofibrous membranes of poly (vinyl alcohol)/chitosan (PVA/CS) loaded with varied salvianic acid A sodium (SAS) contents. Ultrafine fiber mats were prepared with PVA/CS as matrix and SAS as model drug. The structure and morphology of the nanofibrous membranes were characterized by FT-IR and SEM. Drug-loading amount and drug release profiles of these membranes were determined by UV VIS spectra, and the degradation of the membranes was also investigated. Average diameters of PVA/CS/SAS nanofibers with different SAS contents were 280 ≊390 nm. Drug-loading amount of these nanofibrous membranes was high and exhibited sustained and controlled release behavior for SAS. The PVA/CS/SAS nanofibrous membrane prepared in this study loads drug uniformly and has remarkably sustained release behavior, which may offer strategies for the research and development of novel topical drug delivery systems.

Wei G.,Zhejiang University City College
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2010

The observed data of surface settlement caused by construction of Qingchun Road River-Crossing Tunnel in Hangzhou are collected, and a method to select surface settlement values during the construction stage is put forward. Based on the data of ground loss ratio induced by shield tunnel construction in Beijing, Shanghai, Nanjing, Guangzhou, Wuhan, Tianjin and Shenzhen, seventy-one groups of data are statistically analyzed. The results show that the ground loss ratio ranges from 0.2% to 3.01%. About 95.77% of the ground loss ratio is 0.20%~2.0%, and about 43.66% of the ground loss ratio is 0.5% ~1%. The ground loss ratio is 0.20%~2.0% for the cohesive soil area. The ground loss ratio is dependent on the construction level, soil properties and buried depth of the tunnel. With the increase of the tunnel buried depth, the ground loss ratio overall decreases, especially when the buried depth is more than 25 m. The relationship between the ground loss ratio and the tunnel buried depth can be approximately expressed by power functions.

Wu Y.F.,Zhejiang University City College
Applied Mechanics and Materials | Year: 2014

Theory of Machines and Mechanism as a major technology foundation course of mechanical engineering plays an important role in connecting professional education. From the perspective of inspiring mechanical design thinking, put forward the idea of classroom teaching reform for the curriculum. The knowledge of the curriculum is combed; the target ability of the curriculum is specified; the teaching plans are designed to inspire design thinking; the teaching mode is reformed, and the extracurricular learning mode is enhanced. This paper provides a reference for the classroom teaching reform in the other mechanical course. © (2014) Trans Tech Publications, Switzerland.

Wei G.,Zhejiang University City College
Yantu Lixue/Rock and Soil Mechanics | Year: 2013

The mechanism of foundation pit excavation affecting the below existing shield tunnel is researched. 14 cases of the foundation pit instance are collected to make a statistical analysis of measured data. The results show that the maximum vertical displacements of shield tunnel are all uplift, and 64% of the tunnel uplift values exceed the alarm value (10 mm). Based on the measured statistical data, an empirical tunnel maximum uplift value prediction formula below pit is proposed. Measured data of displacements in horizontal direction are fewer surveyed; and they are also small; the convergent small deformations change from "horizontal stretching, vertical compression" to the "horizontal compression, vertical stretching". Based on the at Hangzhou Yan'an Road, underground street passage project, the influence of foundation pit excavation on lower shield tunnel deformation in Hangzhou Metro Line 1 is researched. The measured data of tunnel vertical displacements, horizontal displacements and horizontal convergence deformations are analyzed. The results verify the reliability of theoretical analysis and the proposed formula.

Lin Y.,Zhejiang University City College | Wen L.,Zhejiang University
International Journal of Medical Sciences | Year: 2013

DAI is a leading cause of the patient's death or lasting vegetable state following severe TBI, and up to now the detailed mechanism of axonal injury after head trauma is still unclear. Inflammatory responses have been proved to be an important mechanism of neural injury after TBI. However, most of these studies are concerned with focal cerebral injury following head trauma. In contrast to focal injury, studies on the inflammatory reaction following DAI are only beginning. And in this article, we aimed to review such studies. From the studies reviewed, immune response cells would become reactive around the sites of axonal injury after DAI. Besides, the concentrations of several important inflammatory factors, such as IL-1 family, IL-6 and TNF-a, increased after DAI as well, which implies the participation of inflammatory responses. It can be concluded that inflammatory responses probably participate in the neural injury in DAI, but at present the study of inflammatory responses following DAI is still limited and the clear effects of inflammatory response on axonal injury remain to be more explored. © Ivyspring International Publisher.

Gang W.,Zhejiang University City College
Disaster Advances | Year: 2013

The method established in the present study includes the horizontal distance "L" between the axes of two tunnels and considers the effect of the first tunnel construction on the second tunnel. Meanwhile, it reflects the asymmetric feature of soilsettlement curve. The measured results showed that there was significantly decreased linear relationship between i second/ifirst and h/(DL). The calculation formulae of parameter isecond and ηsecond were proposed.

Lv Y.,Zhejiang University City College
Sensors (Basel, Switzerland) | Year: 2013

A novel zinc porphyrin-containing polyimide (ZPCPI) nanofibrous membrane for rapid and reversible detection of trace amounts of pyridine vapor is described. The membrane displays a distinct color change, as well as dramatic variations in absorption and fluorescent emission spectra, upon exposure to pyridine vapor. This condition allows the detection of the analyte at concentrations as low as 0.041 ppm. The vapochromic and spectrophotometric responses of the membrane are attributed to the formation of the ZPCPI-pyridine complex upon axial coordination. From surface plasmon resonance analysis, the affinity constant of ZPCPI-pyridine complex was calculated to be (3.98 ± 0.25) × 104 L · mol(-1). The ZPCPI nanofibrous membrane also showed excellent selectivity for pyridine vapor over other common amines, confirming its applicability in the manufacture of pyridine-sensitive gas sensors.

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