Bostonia. Volume 17

Founded in 1900, Bostonia magazine is Boston University's main alumni publication, which covers alumni and student life, as well as university activities, events, and programs

Marshall University Music Department Presents the Faculty Woodwind Quintet

https://mds.marshall.edu/music_perf/1079/thumbnail.jp

Spiral Orbit Tribometer

The spiral orbit tribometer (SOT) bridges the gap between full-scale life testing and typically unrealistic accelerated life testing of ball-bearing lubricants in conjunction with bearing ball and race materials. The SOT operates under realistic conditions and quickly produces results, thereby providing information that can guide the selection of lubricant, ball, and race materials early in a design process. The SOT is based upon a simplified, retainerless thrust bearing comprising one ball between flat races (see figure). The SOT measures lubricant consumption and degradation rates and friction coefficients in boundary lubricated rolling and pivoting contacts. The ball is pressed between the lower and upper races with a controlled force and the lower plate is rotated. The combination of load and rotation causes the ball to move in a nearly circular orbit that is, more precisely, an opening spiral. The spiral s pitch is directly related to the friction coefficient. At the end of the orbit, the ball contacts the guide plate, restoring the orbit to its original radius. The orbit is repeatable throughout the entire test. A force transducer, mounted in-line with the guide plate, measures the force between the ball and the guide plate, which directly relates to the friction coefficient. The SOT, shown in the figure, can operate in under ultra-high vacuum (10(exp -9) Torr) or in a variety of gases at atmospheric pressure. The load force can be adjusted between 45 and 450 N. By varying the load force and ball diameter, mean Hertzian stresses between 0.5 and 5.0 GPa can be obtained. The ball s orbital speed range is between 1 and 100 rpm

Experimental Determination of Load Carrying Capacity of Point Contacts at Zero Entrainment Velocity

A capacitance technique was used to monitor the film thickness separating two steel balls of a unique tribometer while subjecting the ball-ball contact to highly stressed, zero entrainment velocity (ZEV) conditions. All tests were performed under a N2 purge (R.H. < 1.0%) and utilized 52100 steel balls (R(sub a) = 0.02 mm). Tribometer operations and capacitance-to-film-thickness accuracy were verified by comparing the film thickness approximations to established theoretical predictions for test conditions involving pure rolling. Pure rolling experiments were performed under maximum contact stresses and entrainment velocities of 1.0 GPa and 1.0 m/s to 3.0 m/s, respectively. All data from these baseline tests conformed to theory. ZEV tests were initiated after calibration of the tribometer and verification of film thickness approximation accuracy. Maximum contact stresses up to 0.57 GPa were supported at zero entrainment velocity with sliding speeds from 6.0 to 10.0 m/s for sustained amounts of time up to 28.8 minutes. The protective lubricating film separating the specimens at ZEV had a thickness between 0.10 and 0.14 mm (4 to 6 min), which corresponds to an approximate L-value of 4. The film thickness did not have a strong dependence upon variations of load or speed. Decreasing the sliding speed from 10.0 m/s to 1 m/s revealed a rapid loss in load support between 3.0 and 1.0 m/s. The formation of an immobile film formed by lubricant entrapment is discussed as an explanation of the load carrying capacity at these zero entrainment velocity conditions, relevant to the ball-ball contact application in retainerless ball bearings

TID Tolerance of Popular CubeSat Components

In this paper we report total dose test results of COTS components commonly used on CubeSats. We investigate a variety of analog integrated circuits, a popular microcontroller (PIC24) as well as SD memory card

Conjugate Addition Routes to 2-alkyl-2,3-dihydroquinolin-4(1H)-ones and 2-alkyl-4-hydroxy-1,2-dihydroquinoline-3-carboxylates

Under CuBr·SMe2/PPh3 catalysis (5/10 mol-%) RMgCl (R = Me, Et, nPr, CH=CH2, nBu, iBu, nC5H11, cC6H11, Bn, CH2Bn, nC11H23) readily (-78 oC) undergo 1,4-addition to Cbz or Boc protected quinolin-4(1H)-ones to provide 2-alkyl-2,3-dihydroquinolin-4(1H)-ones (14 examples, 54-99% yield). Asymmetric versions require AlEt3 to Boc-protected ethyl 6substituted 4(1H)-quinolone-3-carboxylates (6-R group = all halogens, n/i/t-alkyls, CF3) and provide 61-91% yield, 30-86% ee; any halogen, Me, or CF3 provide the highest stereoselectivities (76-86% ee). Additions of AlMe3 or Al(nC8H17)3 provide ~45 and ~75% ee on addition to the parent (6-R = H). Ligand (S)-(BINOL)P-N(CHPh2)(cC6H11) provides the highest ee values engendering addition to the Si face of the 4(1H)-quinolone-3-carboxylate. Allylation and deprotection of a representative 1,4-addition product example confirm the facial selectivity (X-ray)

Natural resource wars in the shadow of the future: Explaining spatial dynamics of violence during civil war

Previous studies on natural resources and civil wars find that the presence of natural resources increases both civil conflict risk and duration. At the same time, belligerents often cooperate over resource extraction, suggesting a temporal variation in the contest over this subnational space. This study argues that parties fight over natural resources primarily when they expect that the conflict is about to end, as the importance of controlling them increases in the post-conflict setting. In contrast, belligerents that anticipate a long war have incentives to avoid fighting near natural resources since excessive violence will hurt the extraction, trade, and subsequent taxation that provide conflict actors with income from the resource. We test our argument using yearly and monthly grid-cell-level data on African civil conflicts for the period 1989–2008 and find support for our expected spatial variation. Using whether negotiations are underway as an indicator about warring parties’ expectations on conflict duration, we find that areas with natural resources in general experience less intense fighting than other areas, but during negotiations these very areas witness most of the violence. We further find that the spatial shift in violence occurs immediately when negotiations are opened. A series of difference-in-difference estimations show a visible shift of violence towards areas rich in natural resources in the first three months after parties have initiated talks. Our findings are relevant for scholarship on understanding and predicting the trajectories of micro-level civil conflict violence, and for policymakers seeking to prevent peace processes being derailed

Dreams and nightmares of liberal international law: capitalist accumulation, natural rights and state hegemony

This article develops a line of theorising the relationship between peace, war and commerce and does so via conceptualising global juridical relations as a site of contestation over questions of economic and social justice. By sketching aspects of a historical interaction between capitalist accumulation, natural rights and state hegemony, the article offers a critical account of the limits of liberal international law, and attempts to recover some ground for thinking about the emancipatory potential of international law more generally

Law, Environment, and the “Nondismal” Social Sciences

Over the past 30 years, the influence of economics over the study of environmental law and policy has expanded considerably, becoming in the process the predominant framework for analyzing regulations that address pollution, natural resource use, and other environmental issues. This review seeks to complement the expansion of economic reasoning and methodology within the field of environmental law and policy by identifying insights to be gleaned from various “nondismal” social sciences. In particular, three areas of inquiry are highlighted as illustrative of interdisciplinary work that might help to complement law and economics and, in some cases, compensate for it: the study of how human individuals perceive, judge, and decide; the observation and interpretation of how knowledge schemes are created, used, and regulated; and the analysis of how states and other actors coordinate through international and global regulatory regimes. The hope is to provide some examples of how environmental law and policy research can be improved by deeper and more diverse engagement with social science