The Complete Jamming Landscape of Confined Hard Discs

An exact description of the complete jamming landscape is developed for a system of hard discs of diameter $\sigma$, confined between two lines separated by a distance $1+\sqrt{3/4} < H/\sigma < 2$. By considering all possible local packing arrangements, the generalized ensemble partition function of jammed states is obtained using the transfer matrix method, which allows us to calculate the configurational entropy and the equation of state for the packings. Exploring the relationship between structural order and packing density, we find that the geometric frustration between local packing environments plays an important role in determining the density distribution of jammed states and that structural "randomness" is a non-monotonic function of packing density. Molecular dynamics simulations show that the properties of the equilibrium liquid are closely related to those of the landscape.Comment: 5 Pages, 4 figure

Use of unbalanced laminates as a screening method for microcracking

State-of-the-art, high temperature polyimide matrix composites, reinforced with continuous graphite fibers are known to be susceptible to intraply cracking when thermally cycled over their useful service temperature range. It is believed that the transply cracking, in part, results from residual stresses caused by differences in coefficients of thermal expansion (CTE) between the polymer matrix and the reinforcement. Thermal cycling tests to investigate this phenomenon involve expensive time and energy consuming programs which are not economically feasible for use as a part of a materials screening process. As an alternative to thermal cycling studies, a study of unbalanced crossply graphite fiber reinforcement composites was conducted to assess the effect of the composite ply layup and surface condition on the residual stresses that remain after the processing of these materials. The residual stresses were assessed by measuring the radii of curvature of the types of laminates that were studied. The temperature at which stress-free conditions existed were determined and a dye penetrant method was used to observe surface damage resulting from excessive residual stress buildup. These results are compared with some published results of thermal cycling tests that were previously conducted on balanced polyimide composites

Thermal expansion of graphite-epoxy between 116 K and 366 K

A Priest laser interferometer was developed to measure the thermal strain of composite laminates. The salient features of this interferometer are that: (1) it operates between 116 K and 366 K; (2) it is easy to operate; (3) minimum specimen preparation is required; (4) coefficients of thermal expansion in the range of 0-5 micro epsilon/K can be measured; and (5) the resolution of thermal strain is on the order of micro epsilon. The thermal response of quasi-isotropic, T300/5208, grahite-epoxy composite material was studied with this interferometer. The study showed that: (1) for the material tested, thermal cycling effects are negligible; (2) variability of thermal response from specimen to specimen may become significant at cryogenic temperatures; and (3) the thermal response of 0.6 cm and 2.5 cm wide specimens are the same above room temperature

Does mClass Reading 3D Predict Student Reading Proficiency on High-Stakes Assessments?

This quantitative, correlational study investigated the relationship between the North Carolina End of Grade Assessment of Reading Comprehension (NCEOG) and mClass Reading 3D assessment in a North Carolina elementary school. It especially examined the degree to which mClass Reading 3D measures predict scores on the reading comprehension portion of the NCEOG. The study was conducted in two parts. Part one utilized quantitative methods to describe the relationship between mClass Reading 3D and NCEOG based on demographic data. Part two utilized quantitative methods to determine the predictability of mClass Reading 3D measures Oral Reading Fluency (ORF) and Text Reading and Comprehension (TRC) to student scale scores on the NCEOG Assessment of Reading Comprehension. Based on the results of this study, the researcher determined that mClass Reading 3D Oral Reading Fluency (ORF) and Text Reading and Comprehension (TRC) measures statistically, significantly predict student scale scores on the NCEOG Assessment of Reading Comprehension

Inequality and Network Structure

This paper explores the manner in which the structure of a social network constrains the level of inequality that can be sustained among its members. We assume that any distribution of value across the network must be stable with respect to coalitional deviations, and that players can form a deviating coalition only if they constitute a clique in the network. We show that if the network is bipartite, there is a unique stable payoff distribution that is maximally unequal in that it does not Lorenz dominate any other stable distribution. We obtain a complete ordering of the class of bipartite networks and show that those with larger maximum independent sets can sustain greater levels of inequality. The intuition behind this result is that networks with larger maximum independent sets are more sparse and hence offer fewer opportunities for coalitional deviations. We also demonstrate that standard centrality measures do not consistently predict inequality. We extend our framework by allowing a group of players to deviate if they are all within distance k of each other, and show that the ranking of networks by the extent of extremal inequality is not invariant in k.inequality;networks;coalitional deviations;power;centrality

Hands on the Green Leaf Labor, Resistance, and Bittersweet Dwelling in Argentina's Yerba Mate Country.

Hands on the Green Leaf is an ethnographic homage to the men, women, and children called tareferos (tarefer@s) who labor to produce yerba mate, the naturally bitter, green tea that is both symbolic drink and staple food in Argentina. No ethnographic account exists of everyday life in yerba mate country while the vast majority of written work on the tea has focused on consumption. Focusing on tarefer@ personhood at the production site in Argentina’s poor Northeastern province of Misiones, this dissertation captures views of the first temporal, material, corporal, and affective spaces of the commodity chain from which 21st century agrarian alienation springs. I construct a “feminist ethnography of connectedness” which both links the lives of producers and consumers in order to ‘defetishize’ commodities and builds bridges between the disciplines of anthropology, agrarian studies, social work and psychology, as well as studies on labor, law, gender, and environment. I practice ethnographic “appearing” by tracing the history of los mensú, the workers who harvested yerba in the Paraná Forest up through the first part of the 20th century, bringing to light the role of women and children. I write on contemporary subjectivity in the yerbales unveiling a “bittersweet dwelling” in which tarefer@s fight weed cover and unfair labor practices to get to the green gold even as they experience the joys of camaraderie and the natural world in the yerbal. The second half of this dissertation contains accounts of tarefer@ resistance including historical highway blockades waged to improve the price of green leaf. I argue that tarefer@s forge temporary spaces of power and democracy on the asphalt. Contributing to legal anthropology and labor and agrarian studies, I analyze too the “culture of work” at play in the everyday labor conflict that jeopardizes food sovereignty. I argue that gender violence undergirds the yerba mate economy by writing the life of Presencia in which I demonstrate the critical value of women’s everyday practices of sustaining life. This dissertation closes with an account of my collaborative work with tarefer@s in Misiones, drawing on theories of empowerment from social work, community psychology, and collaborative anthropology.PhDAnthropologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/116698/1/chejen_1.pd

Development of a Priest interferometer for measurement of the thermal expansion of a graphite epoxy in the temperature range 116-366 K

The thermal expansion behavior of graphite epoxy laminates between 116 and 366 degrees Kelvin was investigated using as implementation of the Priest interferometer concept. The design, construction and use of the interferometer along with the experimental results it was used to generate are described. The experimental program consisted of 25 tests on 25.4 mm and 6.35 mm wide, 8 ply pi/4 quasi-isotropic T300-5208 graphite/epoxy specimens and 3 tests on a 25.4 mm wide unidirectional specimen. Experimental results are presented for all tests along with a discussion of the interferometer's limitations and some possible improvements in its design

Delineation of Landslide, Flash Flood, and Debris Flow Hazards in Utah

During 1982, 1983, and 1984, abnormally wet conditions in Utah triggered flash floods, landslides, and debris flows. Pore pressures built in hillside soils below melting snows and during prolonged periods of rainfall until the mass suddenly gave way, sometimes as a landslide and other times as a non-Newtonian debris flow that moved rapidly long distances down mountain slopes until finally stiffened by moisture loss or velocity loss because of flatter gradients. Also, runoff from heavy rainfall bursts picked up weathered and other loose material that accumulated on land surfaces over long dry periods . The sediment laden waters flowed out of mountain canyons onto lowlands where they deposited their loads, filled channels and c logged culverts, and then spread over the land surface to infiltrate, except as intercepted and diverted by streets, storm sewers, and irrigation canals. These were in turn often over topped to cause flooding in areas with no natural hazard. Snow melt runoff continued over extended periods, keeping stream flows too high to be contained within the clogged streams, and causing water to flow down streets for weeks disrupting traffic and inundating low-lying property. In closed basins, the waters eventually drain into a terminal lake where rising waters gradually inundated large areas. This complex of interrelated phenomena created a hazard situation that is greatest at the toe of the mountain slopes and concentrates where mountain canyons drain onto alluvial fans and the water spreads in a pattern that varies substantially from storm to storm. These hillside areas are prime res identical site s and command a high pr ice in the market. Development that should not be located in high hazard areas is reasonable a little further down slope where the risk is less. Quantitative methods are needed for mapping flood, debris, and landslide risks in these basin margin areas so that objective decisions can be made on where to locate and how to landscape and design buildings. Monitoring programs and warning systems are needed to track emerging hazards, emergency plans, and get people to respond. During two spring months of 1983, Utah sustained direct damages from landslides and debris floods in excess of 250 million dollars. Public official.s and residents were prepared for water flooding. However, neither the scientific community nor the agencies responsible for dealing with emergency situations were prepared for the widespread 1andslides and devastating debris flows. At least 92 significant landslides along a 30-mile length of the Wasatch Front Mountains sent torrents of water and debris down on the residential areas below. Along the Wasatch Plateau, more than 1000 landslides occurred. Additional massive landslides in Spanish Fork Canyon, Utah County, created Thistle Lake, and in 12-Hile Canyon, Sanpete County, dammed a river and sent a 30-foot high flash flood surge down the canyon. These devastating floods, landslides and debris flows were so extensive that 22 of Utah\u27s 28 counties were declared national disaster areas

Combined mechanical loading of composite tubes

An analytical/experimental investigation was performed to study the effect of material nonlinearities on the response of composite tubes subjected to combined axial and torsional loading. The effect of residual stresses on subsequent mechanical response was included in the investigation. Experiments were performed on P75/934 graphite-epoxy tubes with a stacking sequence of (15/0/ + or - 10/0/ -15), using pure torsion and combined axial/torsional loading. In the presence of residual stresses, the analytical model predicted a reduction in the initial shear modulus. Experimentally, coupling between axial loading and shear strain was observed in laminated tubes under combined loading. The phenomenon was predicted by the nonlinear analytical model. The experimentally observed linear limit of the global shear response was found to correspond to the analytically predicted first ply failure. Further, the failure of the tubes was found to be path dependent above a critical load level