scholarly journals Design and fabrication of a freeform mirror generating a uniform illuminance distribution in a rectangular region

2020 ◽  
Vol 44 (4) ◽  
pp. 540-546
Author(s):  
E.S. Andreev ◽  
E.V. Byzov ◽  
D.A. Bykov ◽  
М.А. Moiseev ◽  
L.L. Doskolovich
Keyword(s):  
Numerical Simulations ◽  
Assignment Problem ◽  
Transportation Problem ◽  
Design Method ◽  
Experimental Measurements ◽  
Mass Transportation ◽  
Rectangular Region ◽  
Linear Assignment Problem ◽  
Linear Assignment ◽  
Good Agreement

The design of a freeform mirror generating a uniform illuminance distribution in a rectangular region with angular dimensions of 30°x15° is presented. The design method is based on the formulation of the problem of calculating the "ray-mapping" as a Monge-Kantorovich mass transportation problem and its subsequent reducing to a linear assignment problem. We describe a mirror fabrication process with the use of milling technology and present results of experimental measurements of the light distribution generated by the mirror. The experimental results are in good agreement with the results of numerical simulations and thus confirm the manufacturability of mirrors designed by the method proposed.

Experimental Characterization of a T-Shaped Programmable Multistable Mechanism

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Mohamed Zanaty ◽  
Simon Henein
Keyword(s):  
Numerical Simulations ◽  
Reaction Force ◽  
Experimental Measurements ◽  
Experimental Characterization ◽  
Stable States ◽  
Stability Behavior ◽  
The Stability ◽  
Force Characteristics ◽  
Good Agreement

Programmable multistable mechanisms (PMM) exhibit a modifiable stability behavior in which the number of stable states, stiffness, and reaction force characteristics are controlled via their programming inputs. In this paper, we present experimental characterization for the concept of stability programing introduced in our previous work (Zanaty et al., 2018, “Programmable Multistable Mechanisms: Synthesis and Modeling,” ASME J. Mech. Des., 140(4), p. 042301.) A prototype of the T-combined axially loaded double parallelogram mechanisms (DPM) with rectangular hinges is manufactured using electrodischarge machining (EDM). An analytical model based on Euler–Bernoulli equations of the T-mechanism is derived from which the stability behavior is extracted. Numerical simulations and experimental measurements are conducted on programming the mechanism as monostable, bistable, tristable, and quadrastable, and show good agreement with our analytical derivations within 10%.

scholarly journals Topology-Aware Strategy for MPI-IO Operations in Clusters

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Weifeng Liu ◽  
Jie Zhou ◽  
Meng Guo
Keyword(s):  
Phase I ◽  
Execution Time ◽  
Assignment Problem ◽  
Optimal Assignment ◽  
Local Data ◽  
Two Phase ◽  
File Access ◽  
Linear Assignment Problem ◽  
Linear Assignment

This paper presents the topology-aware two-phase I/O (TATP), which optimizes the most popular collective MPI-IO implementation of ROMIO. In order to improve the hop-bytes metric during the file access, topology-aware two-phase I/O employs the Linear Assignment Problem (LAP) for finding an optimal assignment of file domain to aggregators, an aspect which is not considered in most two-phase I/O implementations. The distribution is based on the local data stored by each process, and its main purpose is to reduce the total hop-bytes of the I/O collective operation. Therefore, the global execution time can be improved. In most of the considered scenarios, topology-aware two-phase I/O obtains important improvements when compared with the original two-phase I/O implementations.

A negative dual rectangle cancellation algorithm for the linear assignment problem

2013 ◽  
Vol 65 (4) ◽  
pp. 673-678 ◽  
Author(s):  
Mohammad S. Sabbagh ◽  
Sayyed R. Mousavi ◽  
Yasin Zamani
Keyword(s):  
Assignment Problem ◽  
Linear Assignment Problem ◽  
Linear Assignment

scholarly journals In Vitro Validation of Finite-Element Model of AAA Hemodynamics Incorporating Realistic Outlet Boundary Conditions

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Ethan O. Kung ◽  
Andrea S. Les ◽  
Francisco Medina ◽  
Ryan B. Wicker ◽  
Michael V. McConnell ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Numerical Simulations ◽  
In Silico ◽  
Physiological State ◽  
Patient Specific ◽  
Experimental Measurements ◽  
Windkessel Model ◽  
Measured Velocity ◽  
Good Agreement

The purpose of this study is to validate numerical simulations of flow and pressure in an abdominal aortic aneurysm (AAA) using phase-contrast magnetic resonance imaging (PCMRI) and an in vitro phantom under physiological flow and pressure conditions. We constructed a two-outlet physical flow phantom based on patient imaging data of an AAA and developed a physical Windkessel model to use as outlet boundary conditions. We then acquired PCMRI data in the phantom while it operated under conditions mimicking a resting and a light exercise physiological state. Next, we performed in silico numerical simulations and compared experimentally measured velocities, flows, and pressures in the in vitro phantom to those computed in the in silico simulations. There was a high degree of agreement in all of the pressure and flow waveform shapes and magnitudes between the experimental measurements and simulated results. The average pressures and flow split difference between experiment and simulation were all within 2%. Velocity patterns showed good agreement between experimental measurements and simulated results, especially in the case of whole-cycle averaged comparisons. We demonstrated methods to perform in vitro phantom experiments with physiological flows and pressures, showing good agreement between numerically simulated and experimentally measured velocity fields and pressure waveforms in a complex patient-specific AAA geometry.

Statistical Physics Algorithms That Converge

1994 ◽  
Vol 6 (3) ◽  
pp. 341-356 ◽  
Author(s):  
A. L. Yuille ◽  
J. J. Kosowsky
Keyword(s):  
Field Theory ◽  
Assignment Problem ◽  
Statistical Physics ◽  
Heuristic Algorithms ◽  
Optimization Problems ◽  
Mean Field Theory ◽  
Mean Field ◽  
Approximate Solutions ◽  
Linear Assignment Problem ◽  
Linear Assignment

In recent years there has been significant interest in adapting techniques from statistical physics, in particular mean field theory, to provide deterministic heuristic algorithms for obtaining approximate solutions to optimization problems. Although these algorithms have been shown experimentally to be successful there has been little theoretical analysis of them. In this paper we demonstrate connections between mean field theory methods and other approaches, in particular, barrier function and interior point methods. As an explicit example, we summarize our work on the linear assignment problem. In this previous work we defined a number of algorithms, including deterministic annealing, for solving the assignment problem. We proved convergence, gave bounds on the convergence times, and showed relations to other optimization algorithms.

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