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71.
M. Koltun D. Faiman S. Goren E.A. Katz E. Kunoff A. Shames S. Shtutina B. Uzan 《Solar Energy Materials & Solar Cells》1996,44(4):1138
A photovoltaic device, of the Schottky-barrier variety, has been fabricated from pure buckminsterfullerene and silver. The paper presents, as motivation for this work, a number of reasons why fullerenes may turn out to be excellent materials for solar cell fabrication. A summary is given of the experimental techniques employed and the results obtained thus far. 相似文献
72.
S. D. Goren C. Korn E. R ssler H. M. Vieth K. Lü ders Z. Gavra J. R. Johnson J. J. Reilly 《Journal of Alloys and Compounds》1994,210(1-2):9-11
The 2H quadrupole coupling constant e2qQ/h and asymmetry parameter η were measured for deuterium-doped Y2BaCuO5 (green phase) where x=0.31 and 0.61 in HxY2BaCuO5 and at temperatures of 180, 300 and 360 K. The values are e2qQ/h = 235 ± 20 kHz and η = 0.05 ± 0.05, independent of x and the temperature. These results, together with previously measured quadrupole coupling constants of other hydrogen-doped Y---Ba---Cu---O compounds, are correlated with IR stretching frequencies of these compounds and support the model that the hydrogen forms an O---H bond. 相似文献
73.
Active snake contours and Kohonen’s self-organizing feature maps (SOMs) are employed for representing and evaluating discrete
point maps of indoor environments efficiently and compactly. A generic error criterion is developed for comparing two different
sets of points based on the Euclidean distance measure. The point sets can be chosen as (i) two different sets of map points
acquired with different mapping techniques or different sensing modalities, (ii) two sets of fitted curve points to maps extracted
by different mapping techniques or sensing modalities, or (iii) a set of extracted map points and a set of fitted curve points.
The error criterion makes it possible to compare the accuracy of maps obtained with different techniques among themselves,
as well as with an absolute reference. Guidelines for selecting and optimizing the parameters of active snake contours and
SOMs are provided using uniform sampling of the parameter space and particle swarm optimization (PSO). A demonstrative example
from ultrasonic mapping is given based on experimental data and compared with a very accurate laser map, considered an absolute
reference. Both techniques can fill the erroneous gaps in discrete point maps. Snake curve fitting results in more accurate
maps than SOMs because it is more robust to outliers. The two methods and the error criterion are sufficiently general that
they can also be applied to discrete point maps acquired with other mapping techniques and other sensing modalities. 相似文献
74.
Lot sizing problems are production planning problems with the objective of determining the periods where production should
take place and the quantities to be produced in order to satisfy demand while minimizing production, setup and inventory costs.
Most lot sizing problems are combinatorial and hard to solve. In recent years, to deal with the complexity and find optimal
or near-optimal results in reasonable computational time, a growing number of researchers have employed meta-heuristic approaches
to lot sizing problems. One of the most popular meta-heuristics is genetic algorithms which have been applied to different
optimization problems with good results. The focus of this paper is on the recent published literature employing genetic algorithms
to solve lot sizing problems. The aim of the review is twofold. First it provides an overview of recent advances in the field
in order to highlight the many ways GAs can be applied to various lot sizing models. Second, it presents ideas for future
research by identifying gaps in the current literature. In reviewing the relevant literature the focus has been on the main
features of the lot sizing problems and the specifications of genetic algorithms suggested in solving these problems. 相似文献
75.
İbrahim Muter Ş. İlker Birbil Kerem Bülbül Güvenç Şahin Hüsnü Yenigün Duygu Taş Dilek Tüzün 《Computers & Operations Research》2013
In this study, we solve a robust version of the airline crew pairing problem. Our concept of robustness was partially shaped during our discussions with small local airlines in Turkey which may have to add a set of extra flights into their schedule at short notice during operation. Thus, robustness in this case is related to the ability of accommodating these extra flights at the time of operation by disrupting the original plans as minimally as possible. We focus on the crew pairing aspect of robustness and prescribe that the planned crew pairings incorporate a number of predefined recovery solutions for each potential extra flight. These solutions are implemented only if necessary for recovery purposes and involve either inserting an extra flight into an existing pairing or partially swapping the flights in two existing pairings in order to cover an extra flight. The resulting mathematical programming model follows the conventional set covering formulation of the airline crew pairing problem typically solved by column generation with an additional complication. The model includes constraints that depend on the columns due to the robustness consideration and grows not only column-wise but also row-wise as new columns are generated. To solve this difficult model, we propose a row and column generation approach. This approach requires a set of modifications to the multi-label shortest path problem for pricing out new columns (pairings) and various mechanisms to handle the simultaneous increase in the number of rows and columns in the restricted master problem during column generation. We conduct computational experiments on a set of real instances compiled from local airlines in Turkey. 相似文献
76.
This paper addresses the issue of finding robust and stable schedules with respect to random disruptions. Specifically, two surrogate measures for robustness and stability are developed. The proposed surrogate measures, which consider both busy and repair time distributions, are embedded in a tabu-search-based scheduling algorithm, which generates schedules in a single-machine environment subject to machine breakdowns. The performance of the proposed scheduling algorithm and the surrogate measures are tested under a wide range of experimental conditions. The results indicate that one of the proposed surrogate measures performs better than existing methods for the total tardiness and total flowtime criteria in a periodic scheduling environment. A comprehensive bibliography is also presented. 相似文献
77.
78.
Semerci Tugce Dizdar Kerem Can Kulkarni Apoorv Dispinar Derya Soraru Gian Domenico Vakifahmetoglu Cekdar 《Journal of Materials Science》2022,57(31):14723-14734
Journal of Materials Science - This paper reports the synthesis and the performance of polymer-derived ceramic filters for molten metal filtration. Two different filter types were studied: foam... 相似文献
79.
The plethora of research on \(\mathcal {NP}\)-hard parallel machine scheduling problems is focused on heuristics due to the theoretically and practically challenging nature of these problems. Only a handful of exact approaches are available in the literature, and most of these suffer from scalability issues. Moreover, the majority of the papers on the subject are restricted to the identical parallel machine scheduling environment. In this context, the main contribution of this work is to recognize and prove that a particular preemptive relaxation for the problem of minimizing the total weighted completion time (TWCT) on a set of unrelated parallel machines naturally admits a non-preemptive optimal solution and gives rise to an exact mixed integer linear programming formulation of the problem. Furthermore, we exploit the structural properties of TWCT and attain a very fast and scalable exact Benders decomposition-based algorithm for solving this formulation. Computationally, our approach holds great promise and may even be embedded into iterative algorithms for more complex shop scheduling problems as instances with up to 1000 jobs and 8 machines are solved to optimality within a few seconds. 相似文献
80.
Inal Yavuz Rızvanoğlu Kerem Yesilada Yeliz 《Universal Access in the Information Society》2019,18(2):387-398
Universal Access in the Information Society - Ensuring web accessibility for all is not an easy task and requires the awareness, understanding and practices of people with different roles. User... 相似文献