546 research outputs found
The New Confrontation Clause
Article published in the Michigan State University School of Law Student Scholarship Collection
A comprehensive study of infrared OH prompt emission in two comets. I. Observations and effective g-factors
We present high-dispersion infrared spectra of hydroxyl (OH) in comets C/2000 WM1 (LINEAR) and C/2004 Q2 (Machholz), acquired with the Near Infrared Echelle Spectrograph at the Keck Observatory atop Mauna Kea, Hawaii. Most of these rovibrational transitions result from photodissociative excitation of H_2O giving rise to OH "prompt" emission. We present calibrated emission efficiencies (equivalent g-factors, measured in OH photons s^(-1) [H_2O molecule]^(-1)) for more than 20 OH lines sampled in these two comets. The OH transitions analyzed cover a broad range of rotational excitation. This infrared database for OH can be used in two principal ways: (1) as an indirect tool for obtaining water production in comets simultaneously with the production of other parent volatiles, even when direct detections of H_2O are not available; and (2) as an observational constraint to models predicting the rotational distribution of rovibrationally excited OH produced by water photolysis
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The Architecture of Transaction Networks: A Comparative Analysis of Hierarchy in Two Sectors
Many products are manufactured in networks of firms linked by transactions, but comparatively little is known about how or why such transaction networks differ. This article investigates the transaction networks of two large sectors in Japan at a single point in time. In characterizing these networks, our primary measure is “hierarchy,” defined as the degree to which transactions flow in one direction, from “upstream” to “downstream.” Our empirical results show that the electronics sector exhibits a much lower degree of hierarchy than the automotive sector because of the presence of numerous inter-firm transaction cycles. These cycles, in turn, reveal that a significant group of firms have two-way “vertically permeable boundaries”: (i) they participate in multiple stages of an industry’s value chain, hence are vertically integrated, but also (ii) they allow both downstream units to purchase intermediate inputs from and upstream units to sell intermediate goods to other sector firms. We demonstrate that the 10 largest electronics firms had two-way vertically permeable boundaries while almost no firms in the automotive sector had adopted that practice
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Swept time-space domain decomposition on GPUs and heterogeneous computing systems
Modern scientific and engineering problems often require simulations with a level of resolution difficult to achieve in reasonable amounts of time—even in effectively parallelized programs. Therefore, applications that exploit high performance computing (HPC) systems have become invaluable in academia and industry over the past two decades. Addressing the questions that arise from continual scientific advancement requires solutions from hardware and software are required to supply the necessary throughput for demand across scientific disciplines.
The most important development on the hardware side has been the General Purpose Graphics Processing Unit (GPGPU), a class of massively parallel device that now composes a substantial portion of the computational power of the top 500 supercomputers. As these systems grow, barriers to increased performance arise from small costs accumulated over innumerable iterations such as latency, the fixed cost of memory accesses, which becomes significantly larger when access requires communication between two distant CPU processes. This thesis implements and analyzes swept time-space domain decomposition, a communication avoiding scheme for time-stepping stencil codes, for GPGPU and heterogeneous (CPU/GPU) architectures.
The GPGPU program significantly improves the execution time of finite-difference solvers for relatively simple one-dimensional time-stepping partial differential equations (PDEs). The swept decomposition code showed speedups of 2-9x compared with simple GPU domain decompositions and 7-300x compared with parallel CPU versions over a range of problem sizes: 103 – 106 spatial points. However, for a more sophisticated one-dimensional system of equations discretized with a second-order finite-volume scheme, the swept rule performs 1.2-1.9x than a standard implementation for all problem sizes. The program targeting heterogeneous systems with distributed memory patterns performs significantly better on both simple problems, speedup 4-18x, and more complex equation systems, speedup 1.5-3x, over the range of problem sizes: 105-107 spatial points. This demonstrates the benefit of GPU architecture and the contingent effectiveness of swept time-space decomposition for accelerating explicit PDE solvers on current computational architectures
Beyond R&D: What Design Adds to a Modern Research University
The government of Singapore is launching a new university, the Singapore University
of Technology and Design (SUTD), that is scheduled to take in its first freshman class in
April, 2012. SUTD, in collaboration with MIT and Zhejiang University, is striving to
establish a 21st century innovation paradigm that recognizes the synergy between
innovation and design. Many aspects of such an exciting development are of interest to
engineering educators and particularly to design educators and two are covered in this
paper.
One challenge addressed in this paper is the possibility for conflicting agendas between
design‐centric education and the goal of becoming a leading research‐intensive
university. An overview of research intended to address this conflict –that of the
International Design Center that is jointly part of MIT and SUTD‐ is given. It is argued
that, rather than conflicting, design‐centric education and research‐intensity are
synergistic for a 21st century university. The second challenge discussed in some depth
is the setting of “culture” for the new institution that encourages bold attempts to
improve the world through technical innovation (“innovation culture”) with breadth in
national cultures (“global culture”) bridging from Western to Asian perspectives.
Relative to the latter item, a central feature are the “Eastern Cultural” curriculum items
being developed by a second SUTD partner university ‐ Zhejiang University
(Hangzhou, China). The breadth of national cultures and a wide academic disciplinary
base as part of the education process are postulated to be enablers for developing a
strong 21st century innovation‐leadership‐culture for the modern research university
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