检索结果-南通市图书馆

Nonlinear vibration analysis of an embedded branched nanofluid-conveying carbon nanotube:Influence of downstream angle,temperature change and two dimensional external magnetic field

在线全文

学校读者我要写书评

暂无评论

Nano Materials Science 2020年第4期2卷 323-332页

作者： A.A.Yinusa M.g.Sobamowo A.o.Adelaja Mechanical Engineering Department University of LagosNigeria

In this study,non-linear thermal-mechanical stability and vibration analyses of different end-shaped single-walled carbon nanotube conveying viscous nano-magnetic fluid embedded in non-linear visco-elastic foundation under the influence of magnetic fields are *** development of the equation of motion was based on Euler-Bernoulli theory,Hamilton principle and nonlocal elasticity *** results of the analytical solutions using galerkin decomposition differential transform method(gDDTM)were validated with existing experimental *** the parametric studies,it was shown that decreasing the temperature difference as well as increasing the downstream angle decreased the system's stability for pre-bifurcation analysis but increased stability of the system for post bifurcation ***,the results obtained from the dynamic behaviour of the system indicated that the magnetic effect had an attenuating impact of about 45%on the system's response at any mode and for any boundary condition *** is hoped that this work will enhance the design and optimization of nano-devices with I,V,Y,L,K and T-shaped junctions under the influence of thermal-magneto-mechanical flow induced vibration.

关键词： Thermal-mechanical vibration Branched single walled carbon nanotube Magnetic field galerkin and differential transformation method Dynamic and stability analysis

Bacterial contamination of orally-consumed crude herbal remedies:A potential source for multi-drug resistant pathogens in man

在线全文

学校读者我要写书评

暂无评论

Asian Pacific Journal of Tropical Medicine 2009年第4期2卷 41-45页

作者： o.g.oyero A.o.B.oyefolu Microbiology Unit Department of BiologyThe PolytechnicIbadanOyo StateNigeria Department of Microbiology Lagos State UniversityLagos StateNigeria

objective:The acceptability of herbal remedies for alleviating discomforts and ill-health has become very popular, on the account of the increasing cost of allopathic medicine for personal health *** observable non-adherence of herbalists to the established World Health organization(WHo) / National Agency for Food and Drug Administration Control(NAFDAC) regulations for the quality control of herbal medicines is an issue for *** view of this,34 popular and widely consumed crude herbal remedies in southwestern,Nigeria were screened for compliance with standard limits for bacterial contamination,bacteria flora and their antibiotic susceptibility ***:Isolates recovered from samples were identified using the cultural, morphological and biochemical *** were also tested for drug sensitivity using standard procedures. Results:A heavy bacteria load ranging from 3.00×10~3-9.58×10~5 CFU/ML and 1.20×10~5- 5.41×10~5 CFU/ML was observed for water and spirit extracted preparations *** bacteria flora cum contaminants were:Staphylococcus aureus,Bacillus cereus,Bacillus subtilis,Pseudomonas aeruginosa, Micrococcus luteus,Lactobacillus plantarum,Klebsiella pneumoniae,Escherichia coli,streptococcus,Shigella, Neisseria,Arthrobacter,Kurthia and Clostridium *** the isolates were multi-drug resistant(MDR) ***:The crude herbal preparations consumed in Nigeria failed to comply with the internationally recognized standards regarding bacteria load and *** presence of MDR pathogens is of greatest concern. It poses a great risk to consumers health and could be a source of introducing MDR organisms into the human *** is the need for the enforcement of established guidelines to ensure the safety of these preparations.

关键词： Herbal remedies Bacterial contamination Multi-drug resistant bacteria Antibiotic susceptibility Quality control

Unwrapping reworked crust at the Columbia supercontinent margin within central southern Amazon Craton using multi-source g.ophysics and g.ochronology data synergy

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

g.oscience Frontiers 2022年第3期13卷 35-52页

作者： João g.Motta P.g.Betts V.T.Meira V.g.Trevisan C.R.de Souza Filho Institute of g.osciences University of CampinasCampinasSão PauloBrazil Camborne School of Mines University of ExeterPenryn CampusPenrynCornwallUnited Kingdom School of Earth Atmosphere and EnvironmentMonash University(Clayton Campus)ClaytonVICAustralia anglo American Níquel Brasil Ltda. Avenida Interlândia502 QD 87LST 68 e 10GoiâniaGoiásBrazil

The g.ometry and evolution of pre-existing basement in accretionary belts bordering supercontinents are often *** interpretation of long-wavelength potential field satellite data can image deep crust structure,improving.our understanding.of lithospheric processes that formed these margins ***,we present a multidisciplinary interpretation of the lithospheric architecture of the central southern Amazon Craton,a fragment of an accretionary belt at the southwestern Columbia supercontinent ***-borne gravity and magnetic data,airborne magnetic data,passive seismic(V_(p)/V_(s) ratio,crustal thickness)and seismic tomography data reveals that basement terranes from the interior of the craton extend into the accretionary margin of *** demonstrate a vertically heterogeneous structure with an underlying strongly reworked pre-Columbia tectonic wedge that sustained prolonged modification during the supercontinent assembly as corroborated by Nd isotope and g.ochronology *** isotope data suggest that the protracted orogenic wedge was influenced by subduction angle shifts over time,including addition of substantial juvenile material during slab retreat *** interplay promoted Craton g.owth at the supercontinent margin while keeping a subtle record of the pre-existing *** findings point to the possible misrepresentation of basement extension and g.ometry of supercontinent margins elsewhere.

关键词： Satellite gravity Satellite magnetics Columbia Accretionary belt Amazon Craton g.ochronology

Rolling-element bearings in China： From ancient times to the 20th century

在线全文

学校读者我要写书评

暂无评论

Frontiers of Mechanical Engineering 2016年第1期11卷 33-43页

作者： Lie SUN ang LI Institute for the History of Natural Sciences Chinese Academy of Sciences Beijing 100190 China

The development of rolling-element bearings in China has spanned a long period. Based on several typical and important cases, the present article reconstructs the history of rolling-element bearings in China by dividing it into four stages according to the various characteristics of the bearings. The first stage represents the origin of rolling beatings in China, which remains controversial because of several suspected races and cages that were likely the components of bearings more than a millennium ago. At the second stage, a type of simple roller bearing was used for astronomical instru- ments not later than the 13th century based on clear philological and physical evidence. A similar bearing was also applied to an abridged armillary in the 17th century. Another type of spherical thrust bearings with rolling elements, which is a key component of a traditional Chinese windmill, could support a rotating shaft that moves rotationally and at an angle. At the third stage, the Chinese began studying and using the so-called European- style bearing since the 17th century. Moreover, over the last 100 years, the modem rolling bearing industry was gradually established in China, particularly because of the technology transfer from the Soviet Union in the 1950s. At the fourth stage, the Chinese government initiated the relatively rapid development of beating technology. The govemment launched the ＂bearing movement＂ from the 1950s to the 1960s to establish the modem bearing industry and to promote rolling bearings as replacement for traditional sliding bearings. Furthermore, a number of large professional factories and institutions in China have continually introduced advanced technology and equip- ment. At present, these companies and institutions play a significant role in the intemational bearing industry.

关键词： rolling-element bearing China early rolling bearings technology transfer bearing movement

Attitude Regulation With Bounded Control in the Presence of Large Disturbances With Bounded Moving Average

在线全文

学校读者我要写书评

暂无评论

IEEE/CAA Journal of Automatica Sinica 2022年第5期9卷 834-846页

作者： ang Li Alessandro Astolfi Ming Liu School of Astronautics Harbin Institute of TechnologyHarbin 150080China Department of Electrical and Electronic Engineering Imperial College LondonLondon SW72AZUK Dipartimento di Ingegneria Civile e Ingegneria Informatica University of Rome Tor VergataRoma 00133Italy IEEE

The attitude regulation problem with bounded control for a class of satellites in the presence of large disturbances,with bounded moving average,is solved using a Lyapunov-like *** analysis and design approaches are introduced in the case in which the underlying system is an integrator and are then applied to the satellite attitude regulation *** performance of the resulting closed-loop systems are studied in detail and it is shown that trajectories are ultimately bounded despite the effect of the persistent *** results on a model of a small satellite subject to large,but bounded in moving average,disturbances are presented.

关键词： control cubeSats robust attitude regulation ultimate boundedness

Design of an all-day electrical power generator based on thermoradiative devices

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2021年第10期64卷 2166-2173页

作者： ZHang Xin Yang g.oFeng YAN MengQi ang Lay Kee ang Yee Sin CHEN JinCan School of Science Jiangnan UniversityWuxi 214122China Science Mathematics and TechnologySingapore University of Technology and DesignSingapore 487372Singapore Department of Physics Xiamen UniversityXiamen 361005China

Energy harvesting from sun and outer space using thermoradiative devices(TRDs),despite being promising renewable energy sources,is limited only to daytime and nighttime period,*** a system with 24-hour continuous electric power generation remains an open question thus ***,a TRD-based power generator that harvests solar energy via concentrated solar irradiation during daytime and via thermal infrared emission towards the outer space at nighttime is proposed,thus achieving the much sought-after 24-hour electrical power ***,a rigorous thermodynamical model is developed to investigate the all-day performance characteristics,parametric optimum design,and the role of various energy loss *** calculated results predict that the daytime TRD-based system yields a peak efficiency of 12.6%under 10 suns,thus sig-nificantly outperforming the state-of-art record-setting solar thermoelectric *** work reveals the potential of TRD towards 24-hour electricity generation and future renewable energy technology.

关键词： sustainable energy HgCdTe solar energy thermoradiative optimum design

Motor skills matter to physical activity——At least for children

在线全文

学校读者我要写书评

暂无评论

Journal of Sport and Health Science 2013年第1期2卷 58-59页

作者： ang Chen Department of Kinesiology University of North Carolina at GreensboroGreensboroNC 27412USA

Physical activity(PA) is an effective means of curbing the prevalence of child obesity,and fundamental skills are hypothesized to be an important factor that determines physically active or inactive behavior in *** evidence suggests that adolescents and young adults with proficient motor skills in sport-related activities are more likely to have a physically active lifestyle.1 Because

关键词：学龄前儿童运动体力预测能力生活方式成年人患病率肥胖症

Semi-oxalate synthesis of (1-x)BaTio3-xM0.5Bi0.5Tio3 (M =Li, Na, K)PTCR materials

在线全文

学校读者我要写书评

暂无评论

Journal of Advanced Ceramics 2016年第2期5卷 117-125页

作者： T.A.PLUTENKo o.I.V'YUNoV A.g.BELoUS o.Z.YANCHEVSKII Vernadskii Institute of general and Inorganic Chemistry of the Ukrainian NAS Prospect Palladina 32/34 Kyiv 142 03680 Ukraine

(1−x)BaTio3–xM0.5Bi0.5Tio3 (M = Li, Na, K) solid solutions were prepared using BaTio3 pre-synthesized by oxalate method. The stability limits of (1−x)BaTio3–xLi0.5Bi0.5Tio3 solid solutions have been established. It was shown that increase in M0.5Bi0.5Tio3 concentration results in reduction of ceramic grain size in the (1−x)BaTio3−xM0.5Bi0.5Tio3 (M = Li, Na, K) system. It was found that the positive temperature coefficient of resistance (PTCR) effect in lead-free materials is due to the presence of a semiconductor core, which is formed by sintering under reducing atmosphere, and dielectric grain boundaries, formed on additional oxidation in air. The use of barium titanate, pre-synthesized by oxalate method, in the synthesis of solid solutions reduced the sintering temperature of ceramics compared with solid state reaction technique. By comparing the electrical properties of the synthesized lead-containing and lead-free materials, it has been shown that lead-free materials exhibit better electrical properties for practical use compared with lead-containing materials.

关键词： lead-free ceramic BaTio3 semi-oxalate method positive temperature coefficient of resistance (PTCR) effect

Methane oxidative carbonylation catalyzed by rhodium chalcogen halides over carbon supports

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Natural gas Chemistry 2008年第1期17卷 1-7页

作者： g.R.Kosmambetoval P.E.Strizhak V.I.gritsenko S.V.Volkov L.B.Kharkova o.g.Yanko o.M.Korduban L.V Pisarzhevsky Institute of Physical Chemistry of National Academy of Sciences of Ukraine pr.Nauki 31Kiev03039Ukraine V.I.Vernadsky Institute of general and Inorganic Chemistry of National Academy of Sciences of Ukraine pr.Pauadina 32/34Kiev03680Ukraine V.I.Vernadsky Institute of general and Inorganic Chemistry of National Academy of Sciences of Ukraine pr.Palladina 32/34Kiev03680Ukraine g.V.Kurdyumov Institute of Metal Physics of National Academy of Sciences of Ukraine 36Vernadskij avKyiv03680Ukraine

gas phase carbonylation of methane is studied in the presence of molecular oxygen over pure carbon carriers and carbon supported rhodium chalcogen halides. Activated carbons and fullerene blacks have been used as carbon supports. XPS and IR-spectroscopy data show the formation of rhodium chalcogen halides in solids prepared by different methods. We have found that the productivity of acetic acid by carbon supported rhodium chalcogen halides depends strongly on the carbon carrier and the method of the catalyst preparation. Namely, the catalyst with highest productivity for the acetic acid is prepared by synthesizing the rhodium chalcogen halide over the carbon support followed by thermal destruction. We have also found that rhodium chalcogen halides over activated carbons are more active compared with fullerene supported catalysts.

关键词： catalysts methane oxidative carbonylation rhodium chalcogen halides carbon supports