Mechanical characterization and modeling of non-linear deformation and fracture of a fiber reinforced metal matrix composite

The nonlinear anisotropic mechanical behavior of an aluminum alloy metal matrix composite reinforced with continuous alumina fibers was determined experimentally. The mechanical behavior of the composite were modeled by assuming that the composite has a periodical microstructure. The resulting unit cell problem was solved with the finite element method. Excellent agreement was found between theoretically predicted and measured stress-strain responses for various tensile and shear loadings. The stress-strain responses for transverse and inplane shear were found to be identical and this will provide a simplification of the constitutive equations for the composite. The composite has a very low ductility in transverse tension and a limited ductility in transverse shear that was correlated to high hydrostatic stresses that develop in the matrix. The shape of the initial yield surface was calculated and good agreement was found between the calculated shape and the experimentally determined shape

Non-invasive single-bunch matching and emittance monitor

On-line monitoring of beam quality for high brightness beams is only possible using non-invasive instruments. For matching measurements, very few such instruments are available. One candidate is a quadrupole pick-up. Therefore, a new type of quadrupole pick-up has been developed for the 26 GeV Proton Synchrotron (PS) at CERN, and a measurement system consisting of two such pick-ups is now installed in this accelerator. Using the information from these pick-ups, it is possible to determine both injection matching and emittance in the horizontal and vertical planes, for each bunch separately. This paper presents the measurement method and some of the results from the first year of use, as well as comparisons with other measurement methods.Comment: 10 pages, 10 figures; added figure, minor textual additions; To be resubmitted to Phys. Rev. ST-A

Mechanical behavior of a continuous fiber reinforced aluminum matrix composite subjected to transverse and thermal loading

The transverse properties of an aluminum alloy metal matrix composite reinforced by continuous alumina fibers were investigated. The composite is subjected to both mechanical and cyclic thermal loading. The results of an experimental program indicate that the shakedown concept of structural mechanics provides a means of describing the material behavior. When the loading conditions are within the shakedown region, the material finally responds in an elastic manner after initial plastic response, and for loading conditions outside the shakedown region, the material exhibits a rapid incremental plastic strain accumulation. The failure strain varies by an order of magnitude according to the operating conditions. Hence, for high mechanical and low thermal loading, the failure strains is small; for low mechanical and high thermal loading, the failure strain is large

Reduction of thermal stresses in continuous fiber reinforced metal matrix composites with interface layers

The potential of using an interface layer to reduce thermal stresses in the matrix of composites with a mismatch in coefficients of thermal expansion of fiber and matrix was investigated. It was found that compliant layers, with properties of readily available materials, do not have the potential to reduce thermal stresses significantly. However, interface layers with high coefficient of thermal expansion can compensate for the mismatch and reduce thermal stresses in the matrix significantly

Extraterritoriality, Externalities, and Cross-Border Trade: Some Lessons from the United States, the European Union, and the World Trade Organization

In this article, process and production method (PPM) rules are analyzed under three jurisdictions: the United States, the European Union (EU), and the World Trade Organization (WTO. The approach is justified by the fact that their rules on interstate trade reflect very similar basic objectives related to anti-protectionism. Moreover, the regimes, to a large extent, share the same structure of rules on prohibition balanced with rules on justification. All in all, the regimes reveal similar syntax. The comparability of the U.S. Dormant Commerce Clause Doctrine with both WTO law and EU free movement law has been highlighted already in previous research

Public Monitoring of Contracts with Nonprofit Organizations: Organizational Mission in Two Sectors

Public officials in the human service delivery system must wrestle with complex decisions regarding utilization of agencies in the nonpublic sector to deliver publicly funded services. Data from a survey of 167 agencies in a major metropolitan area suggest that there are still substantial differences in priorities and service approaches of public and nonpublic agencies. These differences suggest that public officials may need to devote more resources to ascertaining whether and when public agencies should themselves deliver publicly funded services and to strengthening public monitoring of contracts in the private sector

Wireless Communication in Process Control Loop: Requirements Analysis, Industry Practices and Experimental Evaluation

Wireless communication is already used in process automation for process monitoring. The next stage of implementation of wireless technology in industrial applications is for process control. The need for wireless networked control systems has evolved because of the necessity for extensibility, mobility, modularity, fast deployment, and reduced installation and maintenance cost. These benefits are only applicable given that the wireless network of choice can meet the strict requirements of process control applications, such as latency. In this regard, this paper is an effort towards identifying current industry practices related to implementing process control over a wireless link and evaluates the suitability of ISA100.11a network for use in process control through experiments

On a Common Road Towards Sustainable Biofuels? EU and U.S. Approaches to Regulating Biofuels

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Mapping Geomedia Studies: Origins, Trajectories, and Future Directions

This article explores the formation of and future avenues for geomedia studies. Drawing on a citation network analysis, we map the development of the interdisciplinary research terrain from its origins and identify central citation clusters. The term "geomedia" has been used in the humanities and social sciences since at least the early 2010s. Subsequently, geomedia studies have been advanced through an interdisciplinary scholarship from human geography, media and communication studies, and other related research areas, assessing the increasingly complex interplay between media technologies and the production of space. To detect the origins and growth of geomedia studies as an emerging field, we conduct a bibliographic citation and keyword analysis of 57 references from the Web of Science core collection. The generated charts and network graphs reveal that research on geomedia has mainly evolved within media and communication studies. A citation cluster analysis shows how two sub-communities and approaches have emerged, tentatively called "visual geomedia studies" and "urban-sociological geomedia studies." A keyword cluster analysis reveals how the approaches are entangled with different theoretical perspectives. Given the societal relevance and the growing vitality of present-day geomedia studies, this article discusses the prospects of both approaches