检索结果-南通市图书馆

roles of Superthermal Electrons and Adiabatic Heavy Ions on Heavy-Ion-Acoustic Solitary and Shock Waves in a Multi-Component Plasma

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2015年第8期64卷 208-214页

作者： M.G.Shah M.M.rahman M.r.Hossen A.A.Mamun Department of Physics Jahangirnagar University Department of Natural Sciences Daffodil International University

Heavy-ion-acoustic(HIA) waves in an unmagnetized collisionless plasma system comprising superthermal electrons, Boltzmann distributed light ions, and adiabatic positively charged inertial heavy ions have been investigated both numerically and analytically. The well-known reductive perturbation method has been used to derive the Kortewegde Vries(K-d V) and Burgers(BG) equations. The parametric regimes for the existence of both the positive and negative solitary and shock waves have been obtained. The effects of adiabaticity of heavy ions and superthermality of electrons,which are found to notably modify the fundamental features(viz. polarity, amplitude, phase speed, etc.) of HIA solitary and shock waves, are precisely studied. The results of our theoretical investigation can be applicable to understand the characteristics and basic nonlinear structures of HIA waves both in space and laboratory plasma situations.

关键词： heavy-ion acoustic waves superthermality adiabatic

Irrigation Water Use Efficiency of Farmers and Its Determinants: Evidence from a Survey in Northwestern China

在线全文

学校读者我要写书评

暂无评论

Agricultural Sciences in China 2010年第9期9卷 1326-1337页

作者： WANG Xue-yuan College of Economics, Zhejiang Gongshang University, Hangzhou 310018, P.r.China College of Economics Zhejiang Gongshang University Hangzhou 310018 P.R. China

Irrigation water shortage is becoming an increasingly serious problem in agricultural production. In this case, it is very important for policy makers to take measures to improve irrigation water use efficiency, especially in the water-scarce areas. In this paper, the data envelopment analysis （DEA） techniques, based on the concept of input-specific technical efficiency were used to develop farm-level technical efficiency measures and sub-vector efficiencies for irrigation water use. The Tobit regression technique was then adopted to identify the factors that influence irrigation water efficiency differentials under the shortage of water resources. Based on a sample data of 432 wheat farmers in northwestern China, our experimental results of the DEA analysis showed the average technical efficiency of 0.6151. It suggested that wheat farmers could increase their production by as much as 38.49% by using inputs more efficiently. Further, the mean irrigation water efficiency of 0.3065, suggested that wheat farmers could produce the same quantity of wheat using the same quantity of inputs but with 69.35% less water. The results of the Tobit regression analysis showed that the farmer＇s age, income, education level, and the farm size tended to affect the degree of irrigation water efficiency positively, and the channel conditions and different irrigation methods made a significant impact on irrigation water use efficiency. Furthermore, the arrangements of exclusive water property rights and competitive water price mechanism have effectively encouraged the water saving behavior of farmers. These results are valuable for policy makers since it could help to guide policies towards high irrigation water use efficiency.

关键词： irrigation water efficiency determinants data envelopment analysis Tobit regression

Prevention of laryngeal webs through endoscopic keel placement for bilateral vocal cord lesions

在线全文

学校读者我要写书评

暂无评论

Frontiers of Medicine 2018年第3期12卷 301-306页

作者： Jian Chen Yilai Shu Matthew r. Naunheim Min Chen Lei Cheng Haitao Wu Department of Otolaryngology-Head and Neck Surgery Eye Ear Nose and Throat Hospital Fudan University Shanghai Key Clinical Disciplines of Otorhinolaryngology Shanghai 200031 China Department of Otology and Laryngology Harvard Medical School Boston MA 02138 USA Department of Otolaryngology Massachusetts Eye and Ear Infirmary Boston MA 02138 USA

Transoral microresection for treatment of vocal cord lesions involving the anterior commissure may result in anterior glottic webs. In this study, we retrospectively reviewed 54 patients who underwent microsurgery for bilateral lesions involving the anterior commissure and categorized them into two groups. The keel placement and control groups received endoscopic keel placement and mitomycin C, respectively. During the follow-up of at least 1 year, the laryngeal web formation rate significantly decreased in the keel placement group compared with that in the control group （18.6% versus 54.5%, P 〈 0.05）. Furthermore, the voice handicap index-10 scores for patients without web formation decreased in both the keel placement and control groups （P 〈 0.0001 and P 〈 0.001, respectively）. A pseudomembrane covering the vocal cords was detected in 16.3% （7 of 43） cases after keel removal. A total of 100% （7 of 7） of these cases and 2.8% （1 of 36） of the other cases formed laryngeal webs （P 〈 0.0001）. Endoscopic keel placement could be an effective method for preventing anterior glottic webs after surgery for bilateral vocal cord diseases involving the anterior commissure. The pseudomembrane observed at the time of keel removal may imply a high risk of web formation.

关键词： glottic stenosis glottic web laryngeal keel silastic sheets anterior commissure

recent advances and applications of machine learning in solidstate materials science

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

npj Computational Materials 2019年第1期5卷 394-429页

作者： Jonathan Schmidt Mário r.G.Marques Silvana Botti Miguel A.L.Marques Institut für Physik Martin-Luther-Universität06120 Halle-WittenbergHalle(Saale)Germany Institut für Festkörpertheorie und-optik Friedrich-Schiller-Universität JenaMax-Wien-Platz 107743 JenaGermany

One of the most exciting tools that have entered the material science toolbox in recent years is machine *** collection of statistical methods has already proved to be capable of considerably speeding up both fundamental and applied *** present,we are witnessing an explosion of works that develop and apply machine learning to solid-state *** provide a comprehensive overview and analysis of the most recent research in this *** a starting point,we introduce machine learning principles,algorithms,descriptors,and databases in materials *** continue with the description of different machine learning approaches for the discovery of stable materials and the prediction of their crystal *** we discuss research in numerous quantitative structure–property relationships and various approaches for the replacement of first-principle methods by machine *** review how active learning and surrogate-based optimization can be applied to improve the rational design process and related examples of *** major questions are always the interpretability of and the physical understanding gained from machine learning *** consider therefore the different facets of interpretability and their importance in materials ***,we propose solutions and future research paths for various challenges in computational materials science.

关键词： learning gained starting

Using physiological conditions to assess current and future habitat use of a Subarctic frog

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Integrative Zoology 2023年第1期18卷 2-14页

作者： Thomas P.HASTINGS Blake r.HOSSACK LeeAnn FISHBACK Jon M.DAVENPOrT Department of Biology Appalachian State UniversityBooneNorth CarolinaUSA U.S.Geological Survey Northern Rocky Mountain Science Centerand Wildlife Biology ProgramW.A.Franke College of Forestry&ConservationUniversity of MontanaMissoulaMontanaUSA Churchill Northern Studies Centre ChurchillManitobaCanada

Species with especially close dependence on the environment to meet physiological requirements,such as ectotherms,are highly susceptible to the impacts of climate *** change is occurring rapidly in the Subarctic and Arctic,but there is limited knowledge on ectotherm physiology in these *** investigated how environmental conditions and habitat characteristics inﬂuence the physiological conditions and habitat use of wood frogs(rana sylvatica)in a Subarctic landscape near Churchill,Manitoba(Canada).We used plaster models to estimate water loss rates and surface body temperatures among different habitat types and at speciﬁc locations used by radio-tracked *** loss(r2=0.67)and surface temperature(r2=0.80)of plaster models was similar to that of live ***-based water loss rates were greater in tundra habitat than in boreal forest and ecotone *** use of wood frogs was strongly tied with available surface moisture and decreased water loss rates that were observed with plaster *** conditions,such as wind speed and ground tem-perature,explained 58%and 91%of the variation in water balance and temperature of plaster *** physiological conditions may be challenging for semi-aquatic ectotherms in environments vulnerable to future cli-mate *** ability to predict physiological conditions based on environmental conditions,as demonstrated in our study,can help understand how wildlife will respond to climatic changes.

关键词： Arctic climate change landscape physiology water balance wood frog

Quasi-Homeomorphisms and Measures of Finite Energy Integrals of Generalized Dirichlet Forms

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2000年第2期16卷 325-336页

作者： Wei Sun Institute of Applied Mathematics,Chinese Academy of Sciences,Beijing,100080,P.r.China Institute of Applied Mathematics Chinese Academy of Sciences Beijing 100080 P. R. China

We introduce the quasi-homeomorphisms of generalized Dirichlet forms and prove that any quasi-regular generalized Dirichlet form is quasi-homeomorphic to a semi-regular generalized Dirichlet form. Moreover. we apply this quasi-homeomorphism method to study the measures of finite energy integrals of generalized Dirichlet forms. We show that any 1-coexcessive function which is dominated by a function in is associated with a measure of finite energy integral. Consequently, we prove that a Borel set B is-exceptional if and only if μ(B)=0 for any measure μ of finite energy integral.

关键词： Generalized Dirichlet form Quasi-homeomorphism Measure of finite energy integral

Decay rates and electromagnetic transitions of heavy quarkonia

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2015年第12期39卷 19-24页

作者： J.N.Pandya N.r.Soni N.Devlani A.K.rai Applied Physics Department Faculty of Technology & Engineeringthe M S University of Baroda Applied Physics Department Polytechnicthe M S University of Baroda Department of Applied Physics Sardar Vallabhbhai National Institute of Technology

The electromagnetic radiative transition widths for heavy quarkonia, as well as digamma and digluon decay widths, are computed in the framework of the extended harmonic confinement model （ErHM） and Coulomb plus power potential （CPP,） with varying potential index v. The outcome is compared with the values obtained from other theoretical models and experimental results. While the mass spectra, digamma and digluon widths from ErHM as well as CPP v=1 are in good agreement with experimental data, the electromagnetic transition widths span over a wide range for the potential models considered here making it difficult to prefer a particular model over the others because of the lack of experimental data for most transition widths.

关键词： heavy quarkonia radiative decays electromagnetic transitions

On the Solvability of Degenerate Quasilinear Parabolic Equations of Second Order

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2000年第2期16卷 313-324页

作者： Zhenhai Liu Department of Mathematics,Changsha University of Electric Power,Changsha 410077,P.r.China Department of Mathematics Changsha University of Electic Power Changsha 410077 P. R. China

In this paper,we consider nonlinear degenerate quasilinear parabolic initial boundary value problems of second *** results from the theory of pseudomonotone operators,we show that there exists at least one weak soluti... 详细信息

关键词： Quasilinear parabolic Degenerate equation Existence result

Saccharification of Sugarcane Bagasse Using an Enzymatic Extract Produced by Aspergillus fumigatus

在线全文

学校读者我要写书评

暂无评论

Journal of renewable Materials 2018年第2期6卷 169-175页

作者： Kenia F.r.Lamounier Patrisia O.rodrigues Daniel Pasquini Milla A.Baffi Institute of Agricultural Sciences Federal University of Uberlândia(UFU)UberlândiaMG38408-100Brazil Chemistry Institute Federal University of Uberlândia(UFU)UberlândiaMG38408-100Brazil

This study investigates the efficiency of a crude enzymatic extract produced by Aspergillus fumigatus SCBM6 by solid state fermentation(SSF)in the hydrolysis of alkali pretreated sugarcane bagasse(PTB).After SSF using in natura sugarcane bagasse(SCB),the enzymatic extract presented 21.33 U.g^-1 of β-glucosidase and 544.46 U.g^-1 of *** alkaline pretreatment with sodium hydroxide 2%NaOH(w/v)removed 43% of the lignin from PTB and the cellulosic fraction increased to 75%.The hydrolysis was optimized as a function of time,temperature,and concentration of *** hydrolysis,the maximum yield(30.05%)of total released reducing sugars(TrS)was obtained under the following conditions:24 h,55℃,2% of PTB and 3 U.g^-1 of β-glucosidase(CBU).Furthermore,an approximate TrS value(26.4%)was also obtained after saccharification carried out during 6 h,55℃,4% of PTB and 1 *** results indicate that hydrolysis can be performed in a short incubation period and with low enzymatic load for reasonable TrS release.

关键词： A.fumigatus enzymatic hydrolysis sugarcane bagasse alkaline pretreatment solid state fermentation