Control/structure interaction during Space Station Freedom-Orbiter berthing

The berthing maneuver is essential for the construction and assembly of Space Station Freedom (SSF) and has a direct effect on the SSF assembly build up and SSF/Orbiter operations. The effects of flexible body dynamics coupled with the available control system may impose new requirements on the maneuver. The problem is further complicated by the effect of the SSF control system on the Shuttle Remote Manipulator System (SRMS). These effects will play a major role in the development of operational requirements which need to be identified and validated in order to assure total safety and maneuver execution during SSF construction. This paper presents the results of ongoing studies to investigate the Control/Structure Interaction (CSI) during the berthing operations. The problem is formulated in terms of multi-flex body equations of motion for SSF and the SRMS and on-orbit flight control systems for the SRMS and the SSF, which includes the Control Moment Gyro (CMG) and Reaction Control System (RCS) Attitude Control Systems (ACS). The SSF control system designs are based on the Preliminary Design Review (PDR) version of the Honeywell design. The simulation tool used for the analysis is briefly described and the CSI results are presented for given berthing scenarios

Dynamic scheduling of recreational rental vehicles with revenue management extensions

The rental fleet scheduling problem (RFSP) arises in vehicle-rental operations that offer a wide variety of vehicle types to customers, and allow a rented vehicle to migrate to a setdown depot other than the pickup depot. When there is a shortage of vehicles of a particular type at a depot, vehicles may be relocated to that depot, or vehicles of similar types may be substituted. The RFSP involves assigning vehicles to rentals so as to minimise the costs of these operations, and arises in both static and online contexts. The authors have adapted a well-known assignment algorithm for application in the online context. In addition, a network-flow algorithm with more comprehensive coverage of problem conditions is used to investigate the determination of rental pricing using revenue management principles. The paper concludes with an outline of the algorithms use in supporting the operations of a large recreational vehicle rental company

Determining the Solution Space of Vertex-Cover by Interactions and Backbones

To solve the combinatorial optimization problems especially the minimal Vertex-cover problem with high efficiency, is a significant task in theoretical computer science and many other subjects. Aiming at detecting the solution space of Vertex-cover, a new structure named interaction between nodes is defined and discovered for random graph, which results in the emergence of the frustration and long-range correlation phenomenon. Based on the backbones and interactions with a node adding process, we propose an Interaction and Backbone Evolution Algorithm to achieve the reduced solution graph, which has a direct correspondence to the solution space of Vertex-cover. By this algorithm, the whole solution space can be obtained strictly when there is no leaf-removal core on the graph and the odd cycles of unfrozen nodes bring great obstacles to its efficiency. Besides, this algorithm possesses favorable exactness and has good performance on random instances even with high average degrees. The interaction with the algorithm provides a new viewpoint to solve Vertex-cover, which will have a wide range of applications to different types of graphs, better usage of which can lower the computational complexity for solving Vertex-cover

Ultra-low-energy non-volatile straintronic computing using single multiferroic composites

The primary impediment to continued downscaling of traditional charge-based electronic devices in accordance with Moore\u27s law is the excessive energy dissipation that takes place in the device during switching of bits. One very promising solution is to utilize multiferroicheterostructures, comprised of a single-domain magnetostrictive nanomagnet strain-coupled to a piezoelectric layer, in which the magnetization can be switched between its two stable states while dissipating minuscule amount of energy. However, no efficient and viable means of computing is proposed so far. Here we show that such single multiferroic composites can act as universal logic gates for computing purposes, which we demonstrate by solving the stochastic Landau-Lifshitz-Gilbert equation of magnetization dynamics in the presence of room-temperature thermal fluctuations. The proposed concept can overwhelmingly simplify the design of large-scale circuits and portend a highly dense yet an ultra-low-energy computing paradigm for our future information processing systems

Improving Outcomes After Relapse in Ewing's Sarcoma: Analysis of 114 Patients From a Single Institution

The outcome for patients with relapsed Ewing's sarcoma is poor. A retrospective analysis was carried out to identify factors associated with improved survival. Between 1992 and 2002, 114 patients presented with relapsed or progressive disease. Median time to progression/relapse was 13 months (range, 2–128). Treatment at relapse included high dose treatment (HDT) in 29 patients, and surgery or definitive radiotherapy in 29. 2 and 5-year post relapse survival (PRS) was 23.5% and 15.2%, respectively. In multivariate analysis, the most significant factors associated with improved survival were disease confined locally or to the lungs (2-year PRS, 40% versus 6%; P < .001), relapse > 18 months from diagnosis (2-year PRS, 53% versus 8%; P < .001), HDT at relapse (2-year PRS, 62% versus 11%; P < .001), and surgery and/or radiotherapy at relapse (2-year PRS, 51% versus 14%; P < .001). First treatment failure in Ewing's sarcoma is mostly fatal. Improved survival can be achieved in selective patients with aggressive treatment. These improvements are confined to those without bone or bone marrow metastases

The determinants of election to the United Nations Security Council

This is the author's accepted manuscript. The final publication is available at Springer via http://dx.doi.org/10.1007/s11127-013-0096-4.The United Nations Security Council (UNSC) is the foremost international body responsible for the maintenance of international peace and security. Members vote on issues of global importance and consequently receive perks—election to the UNSC predicts, for instance, World Bank and IMF loans. But who gets elected to the UNSC? Addressing this question empirically is not straightforward as it requires a model that allows for discrete choices at the regional and international levels; the former nominates candidates while the latter ratifies them. Using an original multiple discrete choice model to analyze a dataset of 180 elections from 1970 to 2005, we find that UNSC election appears to derive from a compromise between the demands of populous countries to win election more frequently and a norm of giving each country its turn. We also find evidence that richer countries from the developing world win election more often, while involvement in warfare lowers election probability. By contrast, development aid does not predict election