Numerical Simulation Of Impact Effects On Multilayer Fabrics

High strength fabrics provide lightweight impact protection and are employed in a wide range of applications. Examples include body armor for law enforcement and military personnel and orbital debris shielding for the International Space Station. Numerical simulation of impact effects on fabric protection systems is difficult., due to the complex woven structure of the fabric layers and the typical application of fabrics in a multilayer configuration. Recent research has applied a new particle-element method to the simulation of impact effects on multilayer fabrics, applicable over a wide range of impact velocities, for use in body armor and orbital debris shielding design applications.Mechanical Engineerin

Sound Minds in Sound Bodies: Transnational Philanthropy and Patriotic Masculinity in al-Nadi al-Homsi and Syrian Brazil, 1920–32

Established in 1920, al-Nadi al-Homsi in Sao Paulo, Brazil was a young men’s club devoted to ˜Syrian patriotic activism and culture in the American mahjar (diaspora). Founded by a transnational network of intellectuals from Homs, the fraternity committed itself to what it saw as a crucial aspect of Syrian national independence under Amir Faysal: the development of a political middle class and a masculine patriotic culture. Al-Nadi al-Homsi directed this project at Syrian youth, opening orphanages, libraries, and schools in both Syria and in Brazil. In these spaces, men and boys congregated to celebrate a polite male culture centered on secular philanthropy, popular education, and corporeal discipline through sports. This article argues that during the 1920s and 1930s, al-Nadi al-Homsi’s politics of benevolence was part of a larger social milieu that drew analogies between strong Syrian minds and bodies and a sovereign, independent Syrian homeland

Former Ottomans in the ranks: pro-Entente military recruitment among Syrians in the Americas, 1916–18

For half a million ‘Syrian’ Ottoman subjects living outside the empire, the First World War initiated a massive political rift with Istanbul. Beginning in 1916, Syrian and Lebanese emigrants from both North and South America sought to enlist, recruit, and conscript immigrant men into the militaries of the Entente. Employing press items, correspondence, and memoirs written by émigré recruiters during the war, this article reconstructs the transnational networks that facilitated the voluntary enlistment of an estimated 10,000 Syrian emigrants into the armies of the Entente, particularly the United States Army after 1917. As Ottoman nationals, many Syrian recruits used this as a practical means of obtaining American citizenship and shedding their legal ties to Istanbul. Émigré recruiters folded their military service into broader goals for ‘Syrian’ and ‘Lebanese’ national liberation under the auspices of American political support

Transnational Modes and Media: The Syrian Press in the Mahjar and Emigrant Activism during World War I

This article argues that during World War I, the Syrian and Lebanese periodical press in the American mahjar created new space for transnational political activism. In São Paulo, Buenos Aires, and New York City, diasporic journalists and political activists nurtured a new nationalist narrative and political culture in the press. In a public sphere linking mahjar to mashriq, what began with discussions about Ottoman political reform transformed into nationalist debate during the war. Intellectuals constructed and defined the “Syrian” and “Lebanese” national communities in the diaspora's newspapers, but the press also played an important practical role in promoting and shaping patterns of charity, remittances, and political activism towards the homeland. Using materials from this press, the article concludes that the newspaper industry's infrastructure enabled new patterns of political activism across the mahjar, but also channeled Syrian efforts into a complex alliance with France by the eve of the Mandate

Ladies Aid as Labor History: Working-Class Formation in the Mahjar

In the Arabic-speaking mahjar (diaspora), the plight of the working poor was the focus of women’s philanthropy. Scholarship on welfare relief in the interwar Syrian, Lebanese, and Palestinian diaspora currently situates it within a gendered politics of benevolence. This article reconsiders that frame and argues for a class-centered reassessment of “ladies aid” politics exploring the intersections of women’s relief with proletarian mutual aid strategies. Founded in 1917, the Syrian Ladies Aid Society (SLAS) of Boston provided food, shelter, education, and employment to Syrian workers. SLAS volunteers understood their efforts as mitigating the precarities imposed on Syrian workers by the global capitalist labor system. Theirs was both a women’s organization and a proletarian movement led by Syrian women. Drawing from SLAS records and the Syrian American press, the article centers Syrian American women within processes of working-class formation and concludes that labor history of the interwar mahjar requires focus on spaces of social reproduction beyond the factory floor

“Claimed by Turkey as Subjects”: Ottoman Migrants, Foreign Passports, and Syrian Nationality in the Americas, 1915–1925

Unofficial Description: In Arab American studies, it's long been understood that Syrian immigrants became "legally white" in 1915's George Dow v United States. This access to whiteness was critical in getting access to US citizenship. However, US laws governing Syrian racial status also bore implications beyond the US context. Starting with Dow (1915), this chapter examines the implications of wartime laws governing Syrian and Lebanese ethnicity in the United States on emerging nationality codes post-1918. It argues that a "Syrian American legal exceptionalism" in US law divided Arabic-speaking Ottoman immigrants from other Ottoman groups for the purposes of wartime mobilization. US laws set a precedent for the first post-Ottoman laws governing "national origins" as France asserted itself as Syria and Lebanon's administration. In sum, the chapter considers the intrinsic link between the assertion of "post-Ottoman" nationalities by Syrians in the mahjar (diaspora) and the arrival of practical nationalities in the eastern Mediterranean

Strial capillary permeability studied with fluorescent tracers in inbred mice

The stria vascularis generates the endocochlear potential (EP), which relies on the maintenance of ionic boundaries. Strial and spiral ligament capillary permeability to FITC-conjugated dextrans and other tracers was assessed in mice of different strains, with and without prior systemic application of mannitol. Mannitol appeared to increase strial capillary permeability to 4 kDa FITC-dextran and effects of mannitol were clearest for post-injection times of less than 2 hours. Present results agree with previous work in suggesting that cochlear capillaries are very ‘leaky’ under normal conditions

Coupling of Sph and Finite Element Codes for Multi-Layer Orbital Debris Shield Design

Particle-based hydrodynamics models offer distinct advantages over Eulerian and Lagrangian hydrocodes in particular shock physics applications. Particle models are designed to avoid the mesh distortion and state variable diffusion problems which can hinder the effective use of Lagrangian and Eulerian codes respectively. However conventional particle-in-cell and smooth particle hydrodynamics methods employ particles which are actually moving interpolation points. A new particle-based modeling methodology, termed Hamiltonian particle hydrodynamics, was developed by Fahrenthold and Koo (1997) to provide an alternative, fully Lagrangian, energy-based approach to shock physics simulations. This alternative formulation avoids the tensile and boundary instabilities associated with standard smooth particle hydrodynamics formulations and the diffusive grid- to-particle mapping schemes characteristic of particle-in-cell methods. In the work described herein, the method of Fahrenthold and Koo has been extended, by coupling the aforementioned hydrodynamic particle model to a hexahedral finite element based description of the continuum dynamics. The resulting continuum model retains all of the features (including general contact-impact effects) of Hamiltonian particle hydrodynamics, while in addition accounting for tensile strength, plasticity, and damage effects important in the simulation of hypervelocity impact on orbital debris shielding. A three dimensional, vectorized, and autotasked implementation of the extended particle method described here has been coded for application to orbital debris shielding design. Source code for the pre-processor (PREP), analysis code (EXOS), post-processor (POST), and rezoner (ZONE), have been delivered separately, along with a User's Guide describing installation and application of the software

Particle Hydrodynamics with Material Strength for Multi-Layer Orbital Debris Shield Design

Three dimensional simulation of oblique hypervelocity impact on orbital debris shielding places extreme demands on computer resources. Research to date has shown that particle models provide the most accurate and efficient means for computer simulation of shield design problems. In order to employ a particle based modeling approach to the wall plate impact portion of the shield design problem, it is essential that particle codes be augmented to represent strength effects. This report describes augmentation of a Lagrangian particle hydrodynamics code developed by the principal investigator, to include strength effects, allowing for the entire shield impact problem to be represented using a single computer code

Design of orbital debris shields for oblique hypervelocity impact

A new impact debris propagation code was written to link CTH simulations of space debris shield perforation to the Lagrangian finite element code DYNA3D, for space structure wall impact simulations. This software (DC3D) simulates debris cloud evolution using a nonlinear elastic-plastic deformable particle dynamics model, and renders computationally tractable the supercomputer simulation of oblique impacts on Whipple shield protected structures. Comparison of three dimensional, oblique impact simulations with experimental data shows good agreement over a range of velocities of interest in the design of orbital debris shielding. Source code developed during this research is provided on the enclosed floppy disk. An abstract based on the work described was submitted to the 1994 Hypervelocity Impact Symposium