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全层状TiAl基合金拉伸试验断裂过程及机理

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机械工程学报 2008年第1期44卷 40-45页

作者：曹睿林有智陈剑虹 HU d 兰州理工大学甘肃省有色金属新材料重点实验室兰州730050 宁德职业技术学院福安355000 伯明翰大学跨学科材料研究中心英国伯明翰B152TT

通过对全层组织TiAl基合金不同缺口试样进行原位拉伸试验,结合数据分析以及断口形貌的观察,研究TiAl基合金拉伸的断裂过程和断裂机理。研究发现在原位拉伸试验中,对于直缺口试样,裂纹起裂于缺口根部,其断裂过程主要是主裂纹(沿层裂纹)... 详细信息

通过对全层组织TiAl基合金不同缺口试样进行原位拉伸试验,结合数据分析以及断口形貌的观察,研究TiAl基合金拉伸的断裂过程和断裂机理。研究发现在原位拉伸试验中,对于直缺口试样,裂纹起裂于缺口根部,其断裂过程主要是主裂纹(沿层裂纹)首先起裂、扩展、连接,然后形成解理断裂起裂源。这一起裂源形成的同时,在刚好能满足Griffiths脆性解理断裂所需要的临界裂纹尺寸时,引起整个试件发生脆性解理断裂。裂纹首先起裂于层间,层间是薄弱环节,断裂方式是穿层断裂和沿层断裂的混合体,以穿层断裂为主。对于大圆弧和平板试样,这种材料的断裂过程是:首先在较高外加载荷下,在标距范围内比较薄弱的区域沿层开裂,随着外加载荷的进一步增加,这些微裂纹扩展,当微裂纹引起的应力集中和外加载荷共同作用足以引起微裂纹进一步贯穿的瞬间,即能量积累到一定程度时,试样整体发生解理断裂。很多试样的断裂是直接起裂的过程,一旦产生裂纹试样立即解理断裂,即这种材料的强度较高,材料很难产生裂纹,也不易损伤。

关键词： TiAl基合金原位拉伸断裂机理

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轮轨噪声预测模型研究进展

交通运输工程学报 2021年第3期21卷 20-38页

作者：圣小珍成功 THOMPSON d J 葛帅上海工程技术大学城市轨道交通学院上海201620 上海工程技术大学上海市轨道交通振动与噪声控制技术工程研究中心上海201620 西南交通大学牵引动力国家重点实验室四川成都610031 南安普敦大学声与振动研究所汉普郡南安普敦SO171BJ

从轮对振动声辐射预测模型、轨道结构振动声辐射预测模型与轮轨相互作用预测模型等方面,总结了轮轨噪声预测模型的研究进展,阐述了主要的建模方法及其特点,给出了一些典型结果,并提出了需要进一步研究的问题。研究结果表明:在建立轮对... 详细信息

从轮对振动声辐射预测模型、轨道结构振动声辐射预测模型与轮轨相互作用预测模型等方面,总结了轮轨噪声预测模型的研究进展,阐述了主要的建模方法及其特点,给出了一些典型结果,并提出了需要进一步研究的问题。研究结果表明:在建立轮对在给定简谐轮轨力作用下的振动声辐射预测模型时,可以将轮对简化为轴对称弹性体,轮对的振动响应通过一个2维的结构有限元模型来预测,而它的声辐射则通过一个2维的声学边界元模型来确定,这样的建模方法可以全面且方便地考虑轮对旋转所带来的陀螺效应和移动荷载效应;在建立轨道结构在给定的简谐轮轨力作用下的振动声辐射预测模型时,可以将轨道结构简化为无限长周期结构,轨道结构的振动响应通过周期结构理论来分析,而它的声辐射则应用2.5维声学边界元来预测,这样的建模方法可以方便地考虑轮轨力沿轨道的高速移动并大大简化声辐射的计算;在建立轮轨相互作用预测模型时,可以利用轮对和钢轨在轮轨接触点处的频率响应函数或脉冲响应函数,这样的建模方法只以轮轨力为未知量,不但使得相应的微分方程或积分方程未知量少,而且完全考虑了轮对的旋转及沿轨道的移动;轮轨噪声预测还需研究的问题包括高速列车轮对的声辐射、高速轨道相对车体的声辐射、地下铁路轮轨噪声,以及包含降噪措施的轮轨噪声预测模型等。

关键词：轮轨噪声轮对动力学轨道动力学轮轨相互作用 2.5维有限元法 2.5维边界元法

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Natarajania thailandica ***.(Stilbosporaceae,diaporthales)from Thailand

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Phyton-International Journal of Experimental Botany 2021年第2期90卷 677-686页

作者： Monika C.dayarathne Rashika S.Brahmanage Kevin d.Hyde Yong Wang department of Plant Pathology Agriculture CollegeGuizhou UniversityGuiyang550025China Center of Excellence in Fungal Research Mae Fah Luang UniversityChiang Rai57100Thailand Inovative Institute of Plant Health Zhongkai University of Agriculture and EngineeringGuangzhou510225China

A fungus similar to the monotypic genus Natarajania,isolated from dead wood and collected in Thailand,is *** of partial ribosomal LSU and a protein coding gene(RPB2)demonstrated that the new isolate belonged to Stilbosporaceae,diaporthales and genetically different from *** is unique in producing synnematous conidiophores,smooth-walled conidiogenous cells and a flared collarette but lacks an elongated collar-canal which is distinct in the type ***,sequence data and morphological traits are used to introduce the new species,Natarajania thailandica.

关键词： Fungi hyphomycete one new species saprobes taxonomy

Recurrence rates after endoscopic resection of large colorectal polyps:A systematic review and meta-analysis

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World Journal of Gastroenterology 2022年第29期28卷 4007-4018页

作者： Carola Rotermund Roupen djinbachian Mahsa Taghiakbari Markus d Enderle Axel Eickhoff daniel von Renteln Research and Basic Technologies ERBE Elektromedizin GmbHTuebingen 72072Germany division of Internal Medicine Montreal University Hospital CenterMontreal QC H2X 3E4Canada Montreal University Hospital Research Center Montreal University Hospital CenterMontreal QC H2X 3E4Canada department of Internal Medicine II Klinikum HanauHanau 63450Germany

BACKGROUNd Complete polyp resection is the main goal of endoscopic removal of large colonic *** techniques have evolved in recent years and endoscopic submucosal dissection(ESd),endoscopic mucosal resection(EMR)with margin ablation,cold snare polypectomy(CSP),cold EMR,and underwater EMR have been ***,efficacy of these techniques with regard to local recurrence rates(LRRs)vs traditional hot snare polypectomy and standard EMR remains *** To analyze LRR of large colonic polyps in a systematic review and *** MEdLINE,EMBASE,EBM Reviews,and CINAHL were searched for prospective studies reporting LRR or incomplete resection rate(IRR)after colonic polypectomy of polyps≥10 mm,published between January 2011 and July *** outcome was LRR for polyps≥10 *** Six thousand nine hundred and twenty-eight publications were identified,of which 34 prospective studies were *** for polyps≥10 mm at up to 12 mo’follow-up was 11.0%(95%CI,7.1%-14.8%;15 studies;4904 polyps).ESd(1.7%;95%CI,0%-3.4%;3 studies,221 polyps)and endoscopic mucosal resection with margin ablation(3.3%;95%CI,2.2%-4.5%;2 studies,947 polyps)significantly reduced LRR vs standard EMR without(15.2%;95%CI,12.5%-18.0%;4 studies,650 polyps)or with unsystematic margin ablation(16.5%;95%CI,15.2%-17.8%;6 studies,3031 polyps).CONCLUSION LRR is significantly lower after ESd or EMR with routine margin ablation;thus,these techniques should be considered standard for endoscopic removal of large colorectal *** techniques,such as CSP,cold EMR,and underwater EMR require further evaluation in prospective studies before their routine implementation in clinical practice can be recommended.

关键词： Colonoscopy Adenoma Polyp Endoscopic mucosal resection Colorectal cancer

Modeling the impact of dam removal on channel evolution and sediment delivery in a multiple dam setting

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International Journal of Sediment Research 2019年第6期34卷 537-549页

作者： R.E.Poeppl T.Coulthard S.d.Keesstra M.Keiler department of Geography and Regional Research University of Vienna School of Environmental Sciences University of Hull Wageningen Environmental Research Team SoilWater and Land Use 4. University of BernInstitute of Geography

dam removal can generate geomorphic disturbances,including channel bed and bank erosion and associated abrupt/pulsed release and downstream transfer of reservoir sediment,but the type and rate of geomorphic response often are hard to *** situation gets even more complex in systems which have been impacted by multiple dams and a long and complex engineering *** previous studies one-dimensional(1-d) models were used to predict aspects of post-removal channel ***,these models do not consider two-dimensional(2-d) effects of dam removal such as bank erosion processes and lateral *** the current study the impacts of multiple dams and their removal on channel evolution and sediment delivery were modeled by using a 2-d landscape evolution model(CAESAR-Lisflood) focusing on the following aspects:patterns,rates,and processes of geomorphic change and associated sediment delivery on annual to decadal *** current modeling study revealed that geomorphic response to dam removal(i.e.,channel evolution and associated rates of sediment delivery) in multiple dam settings is variable and complex in space and *** in geomorphic system response is related to differences in dam size,the proximity of upstream dams,related buffering effects and associated rates of upstream sediment supply,and emerging feedback processes as well as to the presence of channel stabilization *** types and rates of geomorphic adjustment,using the 2-d landscape evolution model CAESAR-Lisflood,are similar to those reported in previous ***,the use of a 2-d method showed some advantages compared to1-d models,generating spatially varying patterns of erosion and deposition before and after dam removal that provide morphologies that are more readily comparable to field data as well as features like the lateral re-working of past reservoir deposits which further enables the maintenance of sediment delivery downstream.

关键词： Reservoir and river management Landscape evolution modeling Sediment pulses River engineering Legacy effects Complexity

Nanotrains and Self-Assembled Two-dimensional Arrays Built from Carboranes Linked by Hydrogen Bonding of dipyridones

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Nano Research 2008年第5期1卷 412-419页

作者： Takashi Sasaki Jason M.Guerrero Ashley d.Leonard James M.Tour department of Chemistry Department of Mechanical Engineering and Materials ScienceRice UniversityMS 2226100 Main St.HoustonTexas 77005USA

The strong hydrogen bonding ability of 2-pyridones were exploited to build nanotrains on *** wheels on axles difunctionalized with 2-pyridone hydrogen bonding units were synthesized and displayed spontaneous formation of linear nanotrains by self-assembly on SiO_(2)or mica *** using atomic force microscopy confi rmed linear formations with lengths up to 5μm and heights within the range of the molecular height of the carborance-tipped axles.

关键词： Nanovehicles nanotrains 2-pyridone hydrogen bonding self-assembly

Phyllosticta species associated with citrus diseases in China

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Fungal diversity 2012年第1期52卷 209-224页

作者： Xinghong Wang Guoqing Chen Feng Huang Jingze Zhang Kevin d.Hyde Hongye Li Institute of Biotechnology Zhejiang UniversityHangzhouZhejiang 310058People’s Republic of China Key Laboratory of Molecular Biology for Crop Pathogens and Insect Pests of Minstry of Agriculture Zhejiang UniversityHangzhouZhejiang 310058People’s Republic of China School of Science Mae Fah Luang University 333 M.1.T.Tasud Muang DistrictChiang Rai 57100Thailand College of Science Botany and Microbiology DepartmentKing Saud UniversityP.O.Box:2455Riyadh 1145Saudi Arabia

Phyllosticta species associated with diseases of four commercial Citrus species grown in China are ***,496 Phyllosticta strains were isolated from mandarins(Citrus reticulata),pomeloes(***),oranges(***)and lemons(***)in the main citrus producing regions across China,and 74 strains were selected for phylogenetic *** inferred from the sequences of internal transcribed spacer region(ITS1,5.8S nrdNA and ITS2),partial translation elongation factor 1-alpha(TEF1)and partial actin gene(ACT),showed these representative Phyllosticta isolates clustered in four distinct clades corresponding to three known,and one undescribed *** newly resolved taxon,Phyllosticta citrichinaensis was isolated from leaves and fruits of all four Citrus species and is introduced in this *** taxon caused minor damage,showing irregular spots or *** citriasiana,associated with tan spot of pomeloes,was isolated only from pomeloes,and never from lemons,mandarins and *** citricarpa,the citrus black spot pathogen,which is presently subjected to phytosanitary legislation in the EU and United States,was isolated from lemons,mandarins and oranges,but never from *** isolates of *** clustered in two subclades,one from mandarins,the other from oranges and *** was isolated from all four Citrus species as an endophyte,causing false melanose,or together with *** or ***,cultural and biochemical characters were consistent with the results of phylogenetic *** addition,a specific primer pair Pca8/ITS4 was designed and selected,and its corresponding PCR procedure was developed for the detection of *** in this study.

关键词： Citrus black spot disease Biochemical character Phylogeny Morphology Rutaceae Species-specific primer

3d radiative convective flow of ZnO-SAE50nano-lubricant in presence of varying magnetic field and heterogeneous reactions

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Propulsion and Power Research 2019年第4期8卷 339-350页

作者： M.K.Nayak J.Prakash d.Tripathi V.S.Pandey department of Physics IHSESiksha"O"Anusandhan Deemed to be UniversityBhubaneswar751003OdishaIndia department of Mathematics Avvaiyar Government College for WomenKaraikal609602Puducherry-U.T.India department of Mathematics National Institute of TechnologyUttarakhand246174India department of Physics National Institute of Technology DelhiNew DelhiIndia

A numerical simulation is presented to investigate the effect of an exponentially varying magnetic field on three dimensional flow of Zinc Oxide-Society of Automotive Engineers 50 nanolubricant(ZnO-SAE50nano-lubricant)past a stretching *** the impact of homogenous and heterogeneous reactions on the flow of nanolubricant concerned has also taken into *** study has been strengthened by introducing the convection mechanism and the effect of thermal *** transformations are employed to transform the set of partial governing equations into the set of ordinary differential *** suitable boundary conditions are used to obtain the numerical *** numerical results are simulated using Matlab bvp4c solver and validated with the existing *** flow characteristics,thermal characteristics,nanoparticle concentration and some non-dimensional numbers are computed under the influence of the pertinent *** valuable outcome of the current study is that augmented magnetic field strength is the root cause of diminishing axial as well as transverse velocities and growing trend of fluid ***,the coeffi-cients of homogenous and heterogeneous reactions are boons for ascending concentration boundary layer.

关键词： MHd 3d flow ZnO-SAE50nanolubricant Exponential stretching sheet Convective heating mechanism Thermal radiation Heat generation/absorption

Streptophage-mediated control of off-flavour taint producing streptomycetes isolated from barramundi ponds

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Synthetic and Systems Biotechnology 2017年第2期2卷 105-112页

作者： Jodi Anne Jonns Peter Richard Brooks Paul Exley Sue Poole d_Ipek Kurtboke Genecology Research Centre Faculty of ScienceHealthEducation and EngineeringUniversity of the Sunshine CoastMaroochydore DCQLD4558Australia Innovative Food Technologies Department of Agriculture and FisheriesHealth and Food Sciences PrecinctBlock 1039 Kessels RoadCoopers PlainsBrisbaneQLD4108Australia

Off-flavour taint of aquaculture products is a global issue reducing consumer confidence in the farmed produce as they are taken up via the gills of fish,and deposited in the lipids of the *** the fish are not purged,resulting undesirable muddy earthy flavour taint can be tasted by *** undesirable flavour and odour is caused by the terpenoid compounds namely geosmin and 2-methylisoborneol,produced as secondary metabolites by certain bacteria including the cyanobacteria and *** strategies to remediate the problem rely on treating the symptoms not the cause and involve the use of time consuming purging methods and costly *** control using bacteriophages,specific to the problem causing bacteria,offers a natural alternative to chemical control,which might reduce further complications of copper based algaecides and its subsequent implications on water *** an adaptation of such biological control approach streptomycetes isolated from barramundi ponds were tested for their susceptibility to streptophages to understand whether host destruction via phage lysis would subsequently eliminate off-flavour taint productions by these *** the determination of the streptophage susceptibility of the isolates one of the most odourous streptomycete species(USC-14510)was selected to be tested further using different pond simulations resembling real-life *** was tested as the indicator of off-flavour taint production and as it has been previously reported that the cyanobacteria-actinomycete interactions occurring in ponds result in even greater levels of geosmin and 2-methylisoborneol,the geosmin levels for the isolate in the presence of cyanobacteria and streptophages were also *** indicated that the highly odourous Streptomyces species(USC-14510)once infected with streptophages,can lose its capacity to produce off-flavour *** simulation studies also revealed geosmin production

关键词： Actinomycetes Streptomycetes Streptophages Barramundi Aquaculture Geosmin