Lin’an, China
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Liu D.,Zhejiang iversity | Turner J.A.,University of Nebraska - Lincoln
Journal of the Acoustical Society of America | Year: 2017

Techniques of quantitative nondestructive evaluation using attenuation of ultrasonic waves have been proposed as a potential tool for monitoring sintering processes because of the direct connection between the changes of wave propagation characteristics and microstructure properties. However, the influence of these changes during sintering on sound propagation remains unclear. In addition to theoretical investigations, numerical models can be utilized to provide key information for interpreting experimental data quantitatively. In this article, a simplified two-phase model using Voronoi polycrystals is applied to study wave propagation through sintered materials. Finite element simulations are developed with various material and geometric parameters of the two-phase model. Example longitudinal attenuation results are obtained and compared with the scattering theory for different input wave frequencies. The comparison of the numerical results with the theory shows the dependence of the attenuation on the parameters of the correlation function and the two-phase geometry. The results also validate the correlation function formula used in the theory. The influence of the input wave frequency and material properties on the correlation lengths is also discussed. Such numerical models can be used to verify theoretical models efficiently and to design further experimental methods for characterization of microstructures. © 2017 Acoustical Society of America.

Shao Q.,Zhejiang iversity | Shao Q.,Institute of Paper Science And Technology | Cheng C.,Zhejiang iversity | Ong R.G.,Michigan State University | And 2 more authors.
Bioresource Technology | Year: 2013

Bamboo is a fast growing plant found worldwide that has high potential as an energy crop. This project evaluated the effectiveness of AFEX pretreatment for converting moso bamboo (Phyllostachys heterocycla var. pubescens) to fermentable sugars, both with and without pre-soaking in hydrogen peroxide. Pretreatment conditions including temperature, water loading, residence time, ammonia loading, and hydrogen peroxide loadings were varied to maximize hydrolysis yields. The optimal conditions for AFEX were 150. °C, 0.8 or 2.0 (w/w) water loading, 10-30. min residence time, and 2.0-5.0 (w/w) ammonia loading. The optimal conditions for H-AFEX were same AFEX conditions with 0.7-1.9 (w/w) 30% (wt) hydrogen peroxide solutions loading. Using 15 FPU/g glucan cellulase and under optimal conditions, AFEX pretreatment achieved a theoretical sugars yield of 64.8-72.7% and addition of hydrogen peroxide presoaking increased the yield to 83.4-92.1%. It is about 5-fold and 7-fold increase in sugars yield for AFEX-treated and H-AFEX-treated bamboo respectively. © 2013 Elsevier Ltd.

Peng Y.X.,Zaozhuang University | Sun Y.F.,Zhejiang iversity
Advances in Energy Science and Equipment Engineering - Proceedings of International Conference on Energy Equipment Science and Engineering, ICEESE 2015 | Year: 2015

The society and economy of various countries will be affected by global warming. In order to cope with the global climate change, reducing agricultural carbon emissions is one of the important measures. Therefore, it is necessary to study the agricultural carbon emissions. Based on a questionnaire survey of Qiansan village in Zouping County, it is shown that the chemical fertilizer is the most important factor of agricultural carbon emissions, and the electricity and fuel used in agricultural production are also important factors of carbon emissions. Eight variables related to agricultural carbon emissions are chosen for study through regression analysis. The results show that the size of land area, degree of education of farmers, and planting greenhouse are important factors of carbon emissions. In order to reduce agricultural carbon emissions, the government should take active measures to promote scientific farming techniques, improve the cultural quality of the farmers and push scientific greenhouse vegetable cultivation. © 2015 Taylor & Francis Group, London.

Zhang J.-F.,Zhejiang University of Media and Communications | Dai C.-Q.,Zhejiang iversity
Wuli Xuebao/Acta Physica Sinica | Year: 2016

We study a (1+1)-dimensional variable-coefficient Gross-Pitaevskii equation with parabolic potential. A similarity transformation connecting the variable-coefficient Gross-Pitaevskii equation with the standard nonlinear Schrödinger equation is constructed. According to this transformation and solutions of the standard nonlinear Schrodinger equation, we obtain exact rogue wave solutions of variable-coefficient Gross-Pitaevskii equation with parabolic potential. In this solution, a Galilean transformation is used such that the center of optical pulse is Xc = v(T - T0) while the Galilean transformation was not used in previous analysis. By the Galilean transformation, the parameter T0 is added into the solution. It is found that the parameter T0 is important to control the excitations of rogue waves. Moreover, the parameters a1 and a2 in solution are complex parameters which can modulate the behaviors of rogue waves. If they are restricted to real numbers, we can obtain some well-known rogue wave solutions. If the parameter a2 = -1/12, we can have a second-order rogue wave solution. If the parameter a2 is a complex number, the solution can describe rogue wave triplets. Here two kinds of rogue wave triplets, namely, rogue wave triplets I and II are presented. For rogue wave triplet I, at first, two first-order rogue waves on each side are excited, and then a first-order rogue wave in the middle is excited with the increase of time. On the contrary, for rogue wave triplet II, a first-order rogue wave in the middle is initially excited, and then two first-order rogue waves on each side are excited with the increase of time. From these solutions, the controls for the excitations of rogue waves, such as the restraint, maintenance and postponement, are investigated in a system with an exponential-profile interaction. In this system, by modulating the relation between the maximum of accumulated time Tmax and the peak time T0 (or TI; TII), we realize the controls of rogue waves. When Tmax > T0 (or TI; TII), rogue wave is excited quickly, and the atom number of condensates increases; when Tmax = T0 (or TI; TII), rogue wave is excited to the maximum amplitude, then maintains this magnitude for a long time, and the atom number of condensates also increases; when Tmax < T0 (or TI; TII), the threshold of exciting rogue wave is never reached, thus the complete excitation is restrained, and the atom number of condensates reduces. These results can be used to understand rogue waves better, that is, besides their "appearing from nowhere and disappearing without a trace", rogue waves can be controlled as discussed by a similar way in this paper. These manipulations for rogue waves give edification on theory and practical application. © 2016 Chinese Physical Society.

Zhao C.,Nanjing Agricultural University | Zhao C.,Zhejiang iversity | Ding W.,Nanjing Agricultural University | Chen F.,Zhejiang iversity | And 2 more authors.
Bioresource Technology | Year: 2014

Corn stover is one of the main agricultural residues being considered as a cellulosic ethanol feedstock. This work evaluated the effectiveness of AFEX™. 1AFEXTM is a registered trademark of MBI International, Lansing, MI.1 pretreatment for converting corn stover to fermentable sugars, both with and without pre-soaking in hydrogen peroxide. The compositional changes and enzymatic digestibility of AFEX-treated and H-AFEX-treated biomass were investigated. Results showed that most of the polysaccharides remained intact following each of these two methods. Compared with AFEX pretreatment, the H-AFEX process enhanced delignification and enzymatic hydrolysis yields of both glucose and xylose. The maximum glucan and xylan digestibility of H-AFEX process were 87.78% and 90.64%, respectively, and were obtained using 0.7 (w/w) water loading, 1.0 (w/w) ammonia loading, 0.5 (w/w) 30. wt.% hydrogen peroxide loading, and 130. °C for 10. min. The results of the present work show that H-AFEX is a feasible pretreatment to improve the enzymatic saccharification of corn stover for bioethanol production. © 2013 Elsevier Ltd.

Guo M.,Hangzhou Dianzi University | Hui G.,Zhejiang iversity
Journal of Chinese Institute of Food Science and Technology | Year: 2016

In this paper, a pork freshness rapid analysis method based on electronic nose and non-linear feature extraction modeling. Chilled-stored pork samples are measured by electronic nose system for continuous 9 days. At the same time, total volatile basic nitrogen (TVB-N) index is examined to characterize pork freshness according to China standard protocols. Electronic nose measurement data is analyzed by principal component analysis (PCA) and stochastic resonance (SR) methods. PCA can not totally discriminate all pork samples. SR signal-to-noise ratio (SNR) spectrum solves this problem. Pork freshness predicting model is built based on linear fitting of SNR maximal values. Validating experiments demonstrate that the developed model predicts pork freshness with good accuracy, and high efficiency. This method is of field application value. © 2016, Editorial Office of Journal of CIFST. All right reserved.

Song X.,Zhejiang iversity | Li Q.,Zhejiang iversity | Gu H.,Zhejiang iversity
Plant and Soil | Year: 2016

Aims: The combined effects of nitrogen (N) deposition and management practices on fine root decomposition remain unknown. The objective of this study was to investigate the effects of the two factors on fine root decay in Moso bamboo plantations. Methods: This study was performed over a three-year period and included three nitrogen treatments (30, 60, and 90 kg N ha−1 yr.−1) and two management practices (conventional and intensive). Results: Fine root decomposition was significantly affected by N inputs and management practices both separately and in combination (P < 0.01). N inputs had a stronger effect than management practices. The low-N input (30 kg N ha−1 yr.−1) accelerated fine root decomposition and nutrient release, whereas high-N inputs (≥ 60 kg N ha−1 yr.−1) inhibited decomposition and nutrient release. Moreover, intensive management practices strengthened the inhibitory effects of the high-N inputs. Conclusions: Moderate N deposition (< 60 kg N ha−1 yr.−1) may decrease soil carbon storage but increase Moso bamboo productivity, while excessive N deposition (≥ 90 kg N ha−1 yr.−1) may have opposing effects. The combined effects of management practices and nitrogen amendment should be considered when estimating the effects of increasing atmospheric N deposition on plantation ecosystems. © 2016 Springer International Publishing Switzerland

Liang L.,Zhejiang iversity | Zhou M.,Zhejiang iversity
Shengwu Gongcheng Xuebao/Chinese Journal of Biotechnology | Year: 2016

Long terminal repeat (LTR) retrotransposons are mobile DNA sequences that ubiquitously exist in eukaryotic genomes. They replicate themselves in the genome by copy-paste mechanism with RNA as medium. In higher plants, many active LTR retrotransposons have been applied to analyze molecular marker technology, genetic tagging, insertion mutation and gene function. Here, we systematically review the characteristics of plant active LTR retrotransposons, including their structures, copy numbers and distributions. We further analyzed the gag (group-specific antigen) and pol (polymerase) sequence features of different plants active LTR retrotransposons and the distribution patterns of the cis-acting elements in LTR regions. The results show that autonomous active LTR retrotransposons must contain LTR regions and code Gag, Pr, Int, Rt, Rh proteins. Both LTR regions are highly homologous with each other and contain many cis-regulatory elements; RVT and RNase_H1_RT domain are essential for Rt and Rh protein respectively. These results provide the basis for subsequent identification of plant active LTR retrotransposons and their functional analysis. © 2016 Chin J Biotech, All right reserved.

Dai C.-Q.,Zhejiang Agriculture And forestry University | Yu F.-B.,Zhejiang iversity
Wave Motion | Year: 2014

With the help of a modified mapping method, we re-study the (3 + 1)-dimensional Burgers equation and derive three families of variable separation solutions. By selecting appropriate functions in the variable separation solution, we discuss interaction behaviors among flat-top rectangle-soliton and ring-soliton, embedded rectangle-soliton and embedded ring-soliton in a periodic wave background. All interaction behaviors among them are completely elastic, and no phase shift appears after the interaction. These results might be helpful to the understanding of the propagation processes for nonlinear water waves in fluid mechanics such as diverse nonequilibrium, nonlinear phenomena in turbulence and inter-face dynamics. © 2013 Elsevier B.V.

Zhou G.,Zhejiang iversity
Optics Communications | Year: 2014

An analytical expression of a Lorentz-Gauss vortex beam with one topological charge propagating in a strongly nonlocal nonlinear media is derived. The analytical expressions of the beam width, the curvature radius, and the orbital angular momentum density for the Lorentz-Gauss vortex beam with one topological charge have been also presented. The normalized intensity distribution, the relative beam width, the curvature radius, and the orbital angular momentum density distribution of the Lorentz-Gauss vortex beam with one topological charge are demonstrated in the strongly nonlocal nonlinear media, respectively. The normalized intensity, the beam width, the curvature radius, and the orbital angular momentum density versus the axial propagation distance are all periodic and the period is T=πz0/η. The evolution of the propagation property of the Lorentz-Gauss vortex beam with one topological charge has been exhibited in the strongly nonlocal nonlinear media. When the parameter η reaches the critical value, the beam width keeps invariant upon propagation, and the corresponding curvature radius is infinite. The propagation of Lorentz-Gauss vortex beams with larger topological charge propagating in the strongly nonlocal nonlinear media can be analyzed by the same procedure as here. © 2014 Elsevier B.V.

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