Zhang Z.,Zhejiang Shuren University |
Pan E.,University of Akron
Soil Dynamics and Earthquake Engineering | Year: 2017
Surrounding soil may be weakened or strengthened due to construction disturbance of the pile, resulting in soil properties varying gradually in the radial direction. In this paper, an analytical solution is developed to investigate the torsional vibration of an elastic pile embedded in a radially inhomogeneous soil and subjected to a time-harmonic torsional loading. The radially inhomogeneous soil is subdivided into many thin concentric annular sub-zones, with each having constant complex shear modulus in radial direction. The dynamic equilibrium equation of each sub-zone of the soil is then solved and the circumferential displacement and shear stress along the pile-soil interface are obtained by a newly developed method that enforces the continuity conditions between the two adjacent sub-zones. By virtue of the boundary and continuity conditions of the pile-soil system, the torsional impedance at the pile head is derived in an exact closed form in the frequency domain. Some numerical results are presented to study the influence of the soil layer rigidities on the vibration characteristic of the pile-soil system. © 2017
Hu F.,Zhejiang Shuren University
Mathematical Problems in Engineering | Year: 2017
A new sliding mode control model of discrete chaotic systems based on multimodal function series coupling is proposed to overcome the shortcomings of the standard PSO algorithm in multimodal function optimization. Firstly, a series coupled PSO algorithm (PP algorithm) based on multimodal function is constructed, which is optimized by multipeak solution on the basis of the standard PSO algorithm. Secondly, the improved PSO algorithm is applied to search all the extreme points in the feasible domain. Thirdly, the Powell method is used to perform the local optimization of the search results, and the newly generated extreme points are added to the extreme point database according to the same peak judgment operator. Finally, the long training time of PP algorithm can be overcome by the characteristics of fast convergence rate of the cloud mutation model. And also, both the population size and the redundancy can be reduced. Then, the clonal selection algorithm is used to keep the diversity of the population effectively. Simulation results of the sliding mode control of discrete chaotic systems show that the improved PSO algorithm obviously improves the response speed, overshoot, and so on. © 2017 Fengjun Hu.
Hu F.,Zhejiang University of Technology |
Hu F.,Zhejiang Shuren University |
Zhao Y.,Zhejiang University of Technology
International Journal of Applied Mathematics and Statistics | Year: 2013
Under keep the geometrical characteristics of point cloud, efficient processing of the original point cloud data of noise and outliers can greatly improve the search efficiency. A filtering algorithm is proposed to improve existing methods. Firstly, 3D voxel grid is created for the massive point cloud data approximating other points inside the voxel with the centroid of all points; then, the neighborhood of discrete points is analyzed statistically, calculating average distance of every point to its neighboring points and filtering the outliers outside the reference ranges of average distance from the data set; finally, the segmentation rules are improved according to the characteristics of KD-Tree. A large amount of experimental results show that this stable and reliable algorithm can compress and filter the point cloud data quickly and effectively. At the same time, it greatly accelerates the search speed. © 2013 by CESER Publications.
Li W.,Zhejiang University |
Li W.,Zhejiang Shuren University |
Mei X.,Zhejiang University |
Tu Y.Y.,Zhejiang University
Mini-Reviews in Medicinal Chemistry | Year: 2012
The biological activities and mechanisms of tea polyphenols and their polymerics have been attractive issues in cancer research. The inhibition of tea polyphenols on cancer cells decreased cell proliferation and increased apoptosis. Tremendous evidences have shown that tea polyphenols suppress tumor promotion by inhibiting enzyme activities and blocking signal transduction pathways. Specifically, the mitogen activated protein kinases (MAPK) pathways have been implicated as an important target molecular for cancer prevention and therapy. The purpose of this review is to discuss the relationship between tea polyphenols and MAPK signaling pathways in cancer. © 2012 Bentham Science Publishers.
Shen C.,Hangzhou Normal University |
Shen C.,Zhejiang Shuren University |
Zhang P.,Hangzhou Normal University |
Sun Q.,National University of Singapore |
And 5 more authors.
Chemical Society Reviews | Year: 2015
The development of mild and general methods for C-S bond formation has received significant attention because the C-S bond is indispensable in many important biological and pharmaceutical compounds. Early examples for the synthesis of C-S bonds are generally limited to the condensation reaction between a metal thiolate and an organic halide. Recent chemical approaches for C-S bond formation, based upon direct C-H bond functionalization and decarboxylative reactions, not only provide new insights into the mechanistic understanding of C-S coupling reactions but also allow the synthesis of sulfur-containing compounds from more effective synthetic routes with high atom economy. This review intends to explore recent advances in C-S bond formation via C-H functionalization and decarboxylation, and the growing opportunities they present to the construction of complex chemical scaffolds for applications encompassing natural product synthesis, synthetic methodology development, and functional materials as well as nanotechnology. © The Royal Society of Chemistry 2015.
Shen C.,Zhejiang Shuren University |
Shen C.,Hangzhou Normal University |
Xu J.,Hangzhou Normal University |
Yu W.,Hangzhou Normal University |
Zhang P.,Hangzhou Normal University
Green Chemistry | Year: 2014
Aryl sulfones were synthesized using a highly active and easily recoverable heterogeneous Cu catalyst which was prepared by simply stirring an aqueous suspension of chitosan in water with copper salts. The chitosan@copper catalyst catalyzed the coupling reactions of aryl halides with sodium sulfinates to readily give the corresponding sulfones in good to excellent yields. The highly active catalyst can be reused many times without losing its catalytic activity. In addition, by using this protocol, the marketed drug zolimidine (antiulcer) could be synthesized easily. This journal is © the Partner Organisations 2014.
Xu D.,Zhejiang Shuren University |
Li C.,Zhejiang University |
Wen Y.,Zhejiang University |
Liu W.,Zhejiang University
Environmental Pollution | Year: 2013
The use of earthworms as a sublethal endpoint has significantly contributed to the ecological risk assessment of contaminated soils. Few studies have focused on the potential toxicity of PFOS to earthworms in the soil. In this work, artificial soils were tested, and contact filter paper studies were used. The results showed that earthworm growth was generally inhibited. The antioxidant activities of the enzymes superoxide dismutase, peroxidase, catalase and glutathione peroxidase were initially activated and then inhibited. Reduced glutathione content was observed, and malondialdehyde content was elevated over the duration of the exposure. These results suggested that PFOS induced oxidative stress in earthworms. In addition, the values of olive tail moment, tail DNA% and tail length using SCGE showed similar frequency distributions and increased with increases in the PFOS concentration. These results suggest that all concentrations of PFOS cause DNA damage. © 2012 Elsevier Ltd. All rights reserved.
Zhou Z.-S.,Zhejiang Shuren University |
He X.-H.,Zhejiang Institute of Geology
Tetrahedron Letters | Year: 2010
A novel and convenient catalytic method for phosphoryloxylactonization of pentenoic acids is available: the cyclization of 4-pentenoic acids with phosphates using iodobenzene as a recyclable catalyst in combination with m-chloroperbenzoic acid as the terminal oxidant was easily carried out in CF3CH2OH at room temperature, giving phosphoryloxylactons in good yields, some of them had two diastereoisomers. © 2010 Elsevier Ltd. All rights reserved.
Cai X.-o.,Zhejiang Shuren University
Optik | Year: 2010
Based on the whole process of recording and reconstruction of digital holography, we study the formation causes of speckle noise in the reconstructed image and its characteristics. And we reach the conclusions that the little hologram aperture diffraction aggravates the speckle noise and the speckle noise in the reconstructed image is a kind of multiplicative noise. Serving as the basis of these features, we propose the reduction technique for speckle noise. Firstly, we set an appropriate aperture function matching the recording parameter and an aperture size of hologram and deconvolve the reconstructed image of the hologram with it. Secondly, we converted the multiplicative noise into additive noise by means of homomorphic transform and realize the separation of signal and noise. Thirdly, we applied the Wiener filtering to reduce the additive noise. Finally, we carried out the inverse transformation. The proposed reduction technique is illustrated with experimental results. Therefore, the paper offers a brand-new thought and practical way of reducing the speckle noise in the reconstructed image of digital holography. © 2008 Elsevier GmbH. All rights reserved.
Lai X.-J.,Zhejiang Shuren University
Communications in Theoretical Physics | Year: 2011
The exact chirped soliton-like and quasi-periodic wave solutions of (2 + 1)-dimensional generalized nonlinear Schrödinger equation including linear and nonlinear gain (loss) with variable coefficients are obtained detailedly in this paper. The form and the behavior of solutions are strongly affected by the modulation of both the dispersion coefficient and the nonlinearity coefficient. In addition, self-similar soliton-like waves precisely piloted from our obtained solutions by tailoring the dispersion and linear gain (loss). © 2011 Chinese Physical Society and IOP Publishing Ltd.