检索结果-南通市图书馆

Laminated Si3N4/SiC Composites with Self-Sealed Structure

在线全文

学校读者我要写书评

暂无评论

Laminated Si3N4/SiC Composites with Self-Sealed Structure

development of BaTiO3 Based X7R Wafers for Single-Layer Capacitors

The 3～〔rd〕International Conference on High-Performance Ceramics(CICC-3)（2）

作者： Zoran krstic vladimir d.krstic Centre for Manufacturing of Advanced Ceramics and Nanomaterials Queen’s University Nicol Hall Kingston Ontario Canada K7L 3N6

Self-sealed laminar SiN/SiC composites, with different cross-section shapes and various thickness ratios of Si3N4 to SiC, have been fabricated. The laminates consist alternately of thicker Si3N4 layers ranging from 100 to 500μm and thinner SiC layers ranging from 6 to 15μm after sintering. Preliminary results indicate that SiC thin layer forms during sintering according to the reaction Si3N4 + 3C→3SiC + 2N2, which is confirmed by X-ray diffraction. An excellent physical and chemical compatibility between Si3N4 and SiC layers was observed. The self-sealed Si3N4/SiC composites not only demonstrate a superb resistance to delamination, usually associated with the plate-form ones, but also show a high damage-tolerance behavior. The laminated Si3N4/SiC composite with a layer thickness ratio of Si3N4 to SiC of approximately 40 gives the highest value of work of fracture (WOF) of approximately 406 kJ/m3, whereas the highest toughness of 21 MPam1/2 was achieved at the layer thickness ratio of 50. The effects of the relative thickness of SiN and SiC layers on the densification of the laminates are examined and fracture behavior and microstructure of the Si3N4/SiC laminates discussed.

关键词： Laminate Si3N4/SiC Composite Self-sealed Structure.

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Development of BaTiO3 Based X7R Wafers for Single-Layer Capa...

Seismicity,structure and tectonics in the Arctic region

The 3～〔rd〕International Conference on High-Performance Ceramics(CICC-3)（1）

作者： vladimir d. krstic Jack Ng Centre for Manufacturing of Advanced Ceramics and Nanomaterials Nicol HallQueens UniversityKingston OntarioCanada K7L 3N6 REMEC Nanowave 425 Horner AvenueUnit# 1Etobicoke OntarioCanada M8W 4W3

＜正＞ Research on the development and characterization of X7R BaTiO3 dielectric wafers for high frequency single-layer capacitors has been carried out. Commercial BaTiO3 powders were processed and optimized in dielectric constant （εr ）, dissipation factor （dF） and temperature coefficient of capacitance （TCC）. The results indicate a strong effect of sintering temperature on dielectric properties as well as on mechanical properties of the BaTiO3. It has been shown that the highest dielectric constant is achieved at high sintering temperatures （＞1400℃） and lowest TCC at lower sintering temperatures （＜1300℃）. By optimizing fabrication process e.g. dry pressing, cold isostatic pressing, sintering, and machining such as grinding and lapping, BaTiO3 wafers of dielectric constant from 3400 to 3600, with a diameter approximately 50mm and thickness 150μm, have been manufactured successfully. The fabricated thin wafers exhibit the X7R capacitor characteristics of the dissipation factor （＜3%） and temperature coefficient of capacitance （＜±5%） in the temperature range of-55℃to 125℃.

关键词： Barium titanate X7R wafer Single-layer capacitor.

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Geoscience Frontiers 2015年第5期6卷 665-677页

作者： Masaki Kanao vladimir d.Suvorov Shigeru Toda Seiji Tsuboi National Institute of Polar Research.Research Organization of Information and Systems Trofimuk Institute of Petroleum Geology and Geophysics of Siberian Branch Russian Academy of Sciences department of Earth Sciences Faculty of EducationAichi University of Education Institute for Research on Earth Evolution Japan Agency for Marine-Earth Science and Technology

The "Arctic" region,where the North Pole occupies the center of the Arctic Ocean,has been affecting the environmental variation of the Earth from geological time to the ***,the seismic activities in the area are not adequately ***,by conducting long term monitoring of seismic phenomenon as sustainable parameters,our understanding of both the tectonic evolution of the Earth and the dynamic interaction between the cryosphere and geosphere in surface layers of the Earth will *** this paper,the association of the seismicity and structure of the Arctic region,particularly focused on Eurasian continent and surrounding oceans,and its relationship with regional evolution during the Earth’s history is *** target areas cover representative tectonic provinces in the Eurasian Arctic,such as the wide area of Siberia,Baikal Rift *** East Russia,Arctic Ocean together with Greenland and Northern *** on discussion including characteristics of seismicity,heterogeneous structure of the crust and upper mantle,tectonic history and recent dynamic features of the Earth’s surface in the Arctic are summarized.

关键词： Arctic region Seismicity Tectonics Earth’s structu

Spontaneous gastrojejunal fistula is a complication of gastric ulcer

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2007年第3期13卷 483-485页

作者： dorde M ulafi Olivera d Mateji vladimir S duki Miodrag d Vukevi Mirko d Kerkez Clinic of Gastroenterology and Hepatology Institute of Digestive Diseases Clinical Center of Serbia Medical FacultyBelgradeSerbia Clinic of Surgery Institute of Digestive Diseases Clinical Center of SerbiaMedical FacultyBelgradeSerbia Institute of Pulmonary diseases Clinical Center of SerbiaMedical FacultyBelgradeSerbia

Spontaneous gastrojejunal fistula formation is an extremely rare complication of gastric ulcer disease. We report a 77-year old woman who presented with diffuse abdominal pain, weight loss, malaise, nausea, and occasional dark stools. Laboratory tests showed extreme hyposideremic anemia with inflammatory syndrome. In addition, biochemical parameters of malnourishment were presented. Upper endoscopy revealed the patent esophagus along the full length without any pathological changes. Large and deep ulceration with perforation in the small intestine was detected in the posterior gastric wall. The small intestine loop was reached by endoscope through spontaneously developed gastrojejunal fistula. Polytopic biopsies of described ulcerative change were carried out. Histopathologically reepithelialized ulcerous zone was seen in the gastric mucosa. Also, gastrojejunal fistula was visualized after wide opening of hepatogastric and gastrocolic ligament. Jejunal loop 25 cm from ligament of Treitz was attached to mesocolon and posterior gastric wall because of ulcer penetration. Postoperative course was uneventful, Per oral intake started on the 4^th postoperative day, and the patient was discharged on the 8^th postoperative day. In summary, this case indicates that persistent symptoms of peptic ulcer disease associated with nutritional disturbances may be caused by gastrojejunal fistula.

关键词： Gastric ulcer Spontaneous Gastrojejunal fistula

A Three-dimensional Multi-scale Plasticity Model for Metal-Intermetallic Laminate Composites Containing Phases of the L12 Structure

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

Acta Metallurgica Sinica(English Letters) 2018年第12期31卷 1265-1271页

作者： Yana d.Lipatnikova vladimir A.Starenchenko Yuliya V.Solov'eva Larisa A.Valuiskaya Tomsk State University of Architecture and Building Solyanaya Sq.2TomskRussia 634003 Siberian State Medical University 2 Moskovsky traktTomskRussia 634055

A three-dimensional plasticity model was developed and applied to metal-intermetallic laminate composites containingphases of the L12 structure. A multi-scale approach that combined the methods of continuum mechanics and dislocationkinetics was used. This model takes account of the different mechanisms of self-locking superdislocations, the dislocationsand the dislocation walls＇ density storage for each type of layer at the micro-scale. At the meso-scale, the solutions to thedislocation kinetics equations, in the form of stress-strain curves, were used to create the properties of a three-dimensionalrepresentative element. The numerical simulation study of the macroscopic deformation was carried out with the finiteelement method using the dynamic model of continuum mechanics, which included the classical conservation laws,constitutive equations and the equation of state. It was shown that the simulation results generated using this model were ingood agreement with the mechanical tests conducted on the single crystals of the L12 structure. The model provides anexcellent description of the high-temperature plastic strain superlocalization effect of single crystal intermetallics of theLI2 structure. This paper describes the numerical results of the study of the tension and compression tests of metal-intermetallic laminate composites containing phases of the L12 structure. The model allows the description of the dis-tribution of the accumulated plastic strain inhomogeneities and is capable of predicting the strengthening properties andplastic behaviour of the metal-intermetallic laminate composites containing phases of the L12 structure.

关键词： Plasticity model Metal-intermetallic laminate composites Layered composites L12 structure Tension Compression

On finite 2-groups all of whose subgroups are mutually isomorphic

在线全文

学校读者我要写书评

暂无评论

Science China Mathematics 2009年第2期52卷 254-260页

作者： EPULIC vladimir Faculty of Electrical Engineering and Computing University of Zagreb

In this paper we investigate the title groups which we call isomaximal. We give the list of all isomaximal 2-groups with abelian maximal subgroups. Further, we prove some properties of isomaximal 2-groups with nonabelian maximal subgroups. After that, we investigate the structure of isomaximal groups of order less than 64. Finally, in Theorem 14. we show that the minimal nonmetacyclic group of order 32 possesses a unique isomaximal extension of order 64.

关键词： p-groups maximal subgroups minimal nonabelian minimal nonmetacyclic 20d15

Fragmentation model for large L/d (Length over diameter) explosive fragmentation warheads

在线全文

学校读者我要写书评

暂无评论

defence Technology（防务技术） 2017年第4期13卷 300-309页

作者： vladimir M. Gold US Army RdECOM-ARdEC Attn: RDAR-MEE-F Picatinny Arsenal NJ 07806-5000 USA

New advanced numerical computer model enabling accurate simulation of fragmentation parameters of large Length over diameter(L/d)explosively driven metal shells has been developed and *** newly developed large L/d multi-region model links three-dimensional axisymmetric high strain high strain-rate hydrocode analyses with the conventional set of Picatinny Arsenal FRAGmentation(PAFRAG)simulation *** standard PAFRAG modeling technique is based on the Mott's theory of break-up of idealized cylindrical"ring-bombs",in which the length of the average fragment is a function of the radius and velocity of the shell at the moment of break-up,and the mechanical properties of the *** the newly developed multi-region model,each of the shell region,the break-up is assumed to occur instantaneously,whereas the entire shell is modeled to fragment at multiple times,according to the number of the regions *** to PAFRAG methodology,the required input for both the natural and the controlled fragmentation models including the geometry and the velocity of the shell at moment of break-up had been provided from the hydrocode analyses and validated with available experimental *** newly developed large L/d multi-region PAFRAG model has been shown to accurately reproduce available experimental fragmentation data.

关键词： Explosive fragmentation modeling Natural fragmentation Mott model PAFRAG Fragmentation warhead lethality performance

Geotechnical methods of reinforcement of slopes near railroads

在线全文

学校读者我要写书评

暂无评论

Research in Cold and Arid Regions 2015年第5期7卷 469-474页

作者： vladimir d.Vereskun Victor A.Yavna Rostov State Transport University

In order to generate well-based design decisions on reinforcement of landslide slopes and road embankment slopes, a system of combined geotechnical analysis of geological conditions is suggested which includes topographic and geo- physical survey, and laboratory studies of soils using infra-red spectroscopy methods. Calculations of slopes＇ deflected modes are carried out with taking into account elastic and elasto-plastic behavior of soil, and the presence of supporting man-made constructions. Results of the application of the system suggested may be used as criteria for the classification of landslide slopes along permanent ways according to the degree of danger when used for transportation.

关键词： landslide slopes railway track engineering survey computer simulation stability factor

Study of asphaltene reaggregation in toluene/heptane mixture by dynamic and static light scattering

在线全文

学校读者我要写书评

暂无评论

Petroleum Research 2024年第1期9卷 48-54页

作者： vladimir N.Kuryakov Oil and Gas Research Institute of RAS(OGRI RAS) Gubkina Str.3119333MoscowRussian Federation

This paper presents the study of the effect of multiple ultrasonic impacts on submicron asphaltene aggregates in a toluene/heptane solution,conducted with dynamic light scattering *** objects of the study were four samples of asphaltenes obtained from four different *** all samples,the change in the average size of the asphaltene submicron aggregates with time was measured after the addition of a precipitant(heptane)to a solution of asphaltenes in toluene at an amount above the threshold *** aggregates formed in solution after the addition of the precipitant and were subjected to ultrasonic treatment,which led to the destruction of the asphaltene *** of destroyed asphaltenes was *** kinetics of this aggregation were similar to the kinetics of aggregation of asphaltenes after the addition of a *** iterations of asphaltene aggregate destruction in the sample led to a significant change in the kinetics of aggregation:the growth of aggregates slowed and stabilized at a size of approximately 200 nm and 30 nm for the different studied samples.

关键词： Asphaltenes Aggregation Sonication dynamic light scattering Re-aggregation Colloidal stability Resins