993 resultados para 156-949A


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Adiabatic shear localization is a mode of failure that occurs in dynamic loading. It is characterized by thermal softening occurring over a very narrow region of a material and is usually a precursor to ductile fracture and catastrophic failure. This reference source is the first detailed study of the mechanics and modes of adiabatic shear localization in solids, and provides a systematic description of a number of aspects of adiabatic shear banding. The inclusion of the appendices which provide a quick reference section and a comprehensive collection of thermomechanical data allows rapid access and understanding of the subject and its phenomena. The concepts and techniques described in this work can usefully be applied to solve a multitude of problems encountered by those investigating fracture and damage in materials, impact dynamics, metal working and other areas. This reference book has come about in response to the pressing demand of mechanical and metallurgical engineers for a high quality summary of the knowledge gained over the last twenty years. While fulfilling this requirement, the book is also of great interest to academics and researchers into materials performance.

Table of Contents

1Introduction1
1.1What is an Adiabatic Shear Band?1
1.2The Importance of Adiabatic Shear Bands6
1.3Where Adiabatic Shear Bands Occur10
1.4Historical Aspects of Shear Bands11
1.5Adiabatic Shear Bands and Fracture Maps14
1.6Scope of the Book20
2Characteristic Aspects of Adiabatic Shear Bands24
2.1General Features24
2.2Deformed Bands27
2.3Transformed Bands28
2.4Variables Relevant to Adiabatic Shear Banding35
2.5Adiabatic Shear Bands in Non-Metals44
3Fracture and Damage Related to Adiabatic Shear Bands54
3.1Adiabatic Shear Band Induced Fracture54
3.2Microscopic Damage in Adiabatic Shear Bands57
3.3Metallurgical Implications69
3.4Effects of Stress State73
4Testing Methods76
4.1General Requirements and Remarks76
4.2Dynamic Torsion Tests80
4.3Dynamic Compression Tests91
4.4Contained Cylinder Tests95
4.5Transient Measurements98
5Constitutive Equations104
5.1Effect of Strain Rate on Stress-Strain Behaviour104
5.2Strain-Rate History Effects110
5.3Effect of Temperature on Stress-Strain Behaviour114
5.4Constitutive Equations for Non-Metals124
6Occurrence of Adiabatic Shear Bands125
6.1Empirical Criteria125
6.2One-Dimensional Equations and Linear Instability Analysis134
6.3Localization Analysis140
6.4Experimental Verification146
7Formation and Evolution of Shear Bands155
7.1Post-Instability Phenomena156
7.2Scaling and Approximations162
7.3Wave Trapping and Viscous Dissipation167
7.4The Intermediate Stage and the Formation of Adiabatic Shear Bands171
7.5Late Stage Behaviour and Post-Mortem Morphology179
7.6Adiabatic Shear Bands in Multi-Dimensional Stress States187
8Numerical Studies of Adiabatic Shear Bands194
8.1Objects, Problems and Techniques Involved in Numerical Simulations194
8.2One-Dimensional Simulation of Adiabatic Shear Banding199
8.3Simulation with Adaptive Finite Element Methods213
8.4Adiabatic Shear Bands in the Plane Strain Stress State218
9Selected Topics in Impact Dynamics229
9.1Planar Impact230
9.2Fragmentation237
9.3Penetration244
9.4Erosion255
9.5Ignition of Explosives261
9.6Explosive Welding268
10Selected Topics in Metalworking273
10.1Classification of Processes273
10.2Upsetting276
10.3Metalcutting286
10.4Blanking293
 Appendices297
AQuick Reference298
BSpecific Heat and Thermal Conductivity301
CThermal Softening and Related Temperature Dependence312
DMaterials Showing Adiabatic Shear Bands335
ESpecification of Selected Materials Showing Adiabatic Shear Bands341
FConversion Factors357
 References358
 Author Index369
 Subject Index375

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The following series of fishery publications produced in calendar years 1980-85 by the Scientific Publications OffIce of the National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), are listed numerically and indexed by author and subject: Circular, Fishery BuUetin, Marine Fisheries Review, Special Scientific Report-Fisheries, and Technical Report NMFS. Also included is an alphanumeric listing of the NOAA Technical Memorandum NMFS series published in calendar years 1972-85 by NMFS regional offices and fisheries centers. Authors and subjects for the Memoradum series are indexed with the other publication series. (PDF file contains 156 pages.)

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On several classes of n-person NTU games that have at least one Shapley NTU value, Aumann characterized this solution by six axioms: Non-emptiness, efficiency, unanimity, scale covariance, conditional additivity, and independence of irrelevant alternatives (IIA). Each of the first five axioms is logically independent of the remaining axioms, and the logical independence of IIA is an open problem. We show that for n = 2 the first five axioms already characterize the Shapley NTU value, provided that the class of games is not further restricted. Moreover, we present an example of a solution that satisfies the first five axioms and violates IIA for two-person NTU games (N, V) with uniformly p-smooth V(N).

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Based on the EU Regulation 1543/2000 for the improvement of quantity and quality of fishery data the Federal Ministry for Consumer Protection, Food and Agriculture has initiated a national data collection programme, executed by three institutions, Federal Research Centre for Fisheries (BFAFi), Federal Agency for Ariculture and Food and the Federal Research Centre Agriculture, co-ordinated by BFAFi. In 2004 samples have been taken from 943 hauls during 29 commercial fishing trips; 357 000 fish have been measured. From 2002 to 2004 the number of length and weight and measurements, and age determinations could increased by 32, 65 and 156 % resp. Pilot inquiries have been carried out to prepare also the collection of economical date of fishing vessels and of fish processing plants from 2006.

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A research was conducted in thirty approximately 100 sq.m earthern ponds of the Brackishwater Aquaculture Centre (BAC), College of Fisheries, University of the Philippines, Leganes Iloilo from November 7, 1982 to March 7, 1983 to evaluate the effects of nine supplemental feeds containing different protein: energy ratios on the growth and survival of Tilapia nilotica in brackishwater ponds. Nine supplemental feeds formulated were with protein levels of 20%, 25%, and 30% each at three energy levels of 3,000 kcals; 3,500 kcals; and 4,000 kcals. There was a control treatment with no feeding so that mean weight gain growth rate, feed conversion rate, and survival were determined. Fish fingerlings were acclimated from 0-29 ppt. salinity before the experiment and 20% of fish in each treatment were sampled after every 30 days. Growth rates were significantly different and increased with increasing energy level at the 30% protein feeds but decreased at high energy levels in the 20% and 25% protein feeds. Feed conversion was significantly different due to interaction between protein and energy levels in the feeds, and was better at the 30:3,500 kcals feeds having a feed conversion of 1.55 g. Survival was not significantly different

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本书系统地介绍了材料微尺度力学行为的尺寸效应实验现象,重点介绍了几种代表性的微尺度应变梯度塑性理论及对微尺度实验现象的解释;以及对裂纹尖端微尺度范围内解理断裂的应用。融会贯通的介绍了国内外学者的原创性工作和创新性学术思想。 全书共8章。第1章介绍了应变梯度塑性理论的应用背景及经典微极理论;第2章介绍了金属材料典型的微尺度力学实验现象;第3~7章介绍了几种典型的应变梯度理论及其应用;第8章介绍了应变梯度理论在微观断裂力学中的应用。 本书适合从事固体微尺度力学、先进材料的微结构设计与力学性能优化、微机电和微电子元件力学行为研究的科技工作者及工程师使用和参考,也可供力学专业及材料专业的高年级本科生和研究生阅读参考。

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Self-organized generation of transverse waves associated with the transverse wave instabilities at a diverging cylindrical detonation front was numerically studied by solving two-dimensional Euler equations implemented with an improved two-step chemical kinetic model. After solution validation, four mechanisms of the transverse wave generation were identified from numerical simulations, and referred to as the concave front focusing, the kinked front evolution, the wrinkled front evolution and the transverse wave merging, respectively. The propagation of the cylindrical detonation is maintained by the growth of the transverse waves that match the rate of increase in surface area of the detonation front to asymptotically approach a constant average number of transverse waves per unit length along the circumference of the detonation front. This cell bifurcation phenomenon of cellular detonations is discussed in detail to gain better understanding on detonation physics.

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[EN] Atemschaukel approaches the falling apart and survival in a historically loaded space, such as a labour camp. This novel offers a relevant research field for the space analysis, focused from the perspective of the Spatial Turn, as not only this theoretical frame but also Herta Müller herself conceive of space as a process, unterstood as a reciprocal interaction with the social practice, thus as a spatial and social construct. The representation of space in Atemschaukel is described in this article as a “swinging movement between boxes and abyss”, where the discourse of Leopold Auberg’s memories oscillates between closed and square spaces, on one hand, and open and giddy spaces, on the other hand. In this oscillating movement it is the open spaces that will most clearly show the process of inner destruction of the subject in such oppressive situations as on labour camps, as well as the permanent damages of deportation.

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The involvement of women in the marketing of frozen fish in Lagos State (Nigeria) was examined in this study. Two hundred questionnaires were administered to fish marketers in five markets randomly selected within the Lagos metropolis based on their storage capacities. These markets were Balogun (500 tones), Idumagbo and Idumota (250 tonnes each) Obalende and Epetedo (37.5 tonnes each). From the study results, a greater percentage of women (64.2%) are actively involved in marketing of frozen fish in the study areas. Over 56% of these traders are retailers while about 33% are wholesalers. More than 91% of the marketers were found to be literate. A high percentage of the frozen fish are imported (68%), 27% from coastal fishing and 5% from riverine fishing. The commonest fish in the markets were titus (34%), sardine (32%), hake 19%, catfish 10% and argentine 5%. Catfish has the highest profit margin. The greatest problem of these traders is the lack of modern storage facilities and where available, the erratic power supply constitutes a problem

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The carbohydrate, protein and lipid contents of the food ingested and their absorption in the intestine of Sarotherodon melanotheron inhabiting Awba lake in Ibadan, Nigeria, were investigated. Total carbohydrates of the ingested food ranged from 39.33 to 55.38% (mean = 48.70% while total protein and total lipid ranged from 10.10 to 17.13% (mean = 12.91%) and 7.79 to 8.96% (mean = 8.28%) dry weight, respectively. Calculated total percentages absorbed were 54.86-62.01 (mean 58.07) carbohydrates 47.33-54.06 (mean = 50.43) protein and 43.27-52.23% (mean 46.56) lipid. Absorption of protein and carbohydrate occurred mostly in the fore-gut (the first one-third of the intestine), while lipid was mostly absorbed in the mid-gut (the second one-third of the intestine). Dietary carbohydrate, protein and lipid contents of the food as well as the absorptive capacity of the intestine for these components of the food varied with size of fish

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En la mitología vasca existen numerosas narraciones cuyo protagonista presenta rasgos de similitud con el Polifemo de la mitología griega. En este trabajo se recopilan y analizan las diferentes populares o legendarias en que aparece bajo descripciones o denominaciones diversas: pastor (gigante) antropófago anónimo, begibakarra (“ojo único), gentil, sorgina (“bruja”), basajaun, Tártalo, Tártaro, Ojanco, Torto, Alarabi, Cíclope, y se relacionan con el modelo literario del Cíclope griego.