scholarly journals Fast and Near-Optimal Timing-Driven Cell Sizing under Cell Area and Leakage Power Constraints Using a Simplified Discrete Network Flow Algorithm

VLSI Design ◽  
2013 ◽  
Vol 2013 ◽  
pp. 1-15
Author(s):  
Huan Ren ◽  
Shantanu Dutt
Keyword(s):  
Cell Size ◽  
Network Flow ◽  
Optimization Methods ◽  
Leakage Power ◽  
Optimal Timing ◽  
Optimal Method ◽  
Efficient Manner ◽  
Power Constraints ◽  
Model Cell ◽  
Cell Sizing

We propose a timing-driven discrete cell-sizing algorithm that can address total cell size and/or leakage power constraints. We model cell sizing as a “discretized” mincost network flow problem, wherein available sizes of each cell are modeled as nodes. Flow passing through a node indicates the choice of the corresponding cell size, and the total flow cost reflects the timing objective function value corresponding to these choices. Compared to other discrete optimization methods for cell sizing, our method can obtain near-optimal solutions in a time-efficient manner. We tested our algorithm on ISCAS’85 benchmarks, and compared our results to those produced by an optimal dynamic programming- (DP-) based method. The results show that compared to the optimal method, the improvements to an initial sizing solution obtained by our method is only 1% (3%) worse when using a 180 nm (90 nm) library, while being 40–60 times faster. We also obtained results for ISPD’12 cell-sizing benchmarks, under leakage power constraint, and compared them to those of a state-of-the-art approximate DP method (optimal DP runs out of memory for the smallest of these circuits). Our results show that we are only 0.9% worse than the approximate DP method, while being more than twice as fast.

scholarly journals Higher-order structure of polymer melt described by persistent homology

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yohei Shimizu ◽  
Takanori Kurokawa ◽  
Hirokazu Arai ◽  
Hitoshi Washizu
Keyword(s):  
Cell Size ◽  
Md Simulation ◽  
Persistent Homology ◽  
Polymer Melt ◽  
Higher Order ◽  
Polymer Materials ◽  
Order Structure ◽  
Materials Informatics ◽  
Optimal Method ◽  
Amorphous Nature

AbstractThe optimal method of the polymer Materials Informatics (MI) has not been developed because the amorphous nature of the higher-order structure affects these properties. We have now tried to develop the polymer MI’s descriptor of the higher-order structure using persistent homology as the topological method. We have experimentally studied the influence of the MD simulation cell size as the higher-order structure of the polymer on its electrical properties important for a soft material sensor or actuator device. The all-atom MD simulation of the polymer has been calculated and the obtained atomic coordinate has been analyzed by the persistent homology. The change in the higher-order structure by different cell size simulations affects the dielectric constant, although these changes are not described by a radial distribution function (RDF). On the other hand, using the 2nd order persistent diagram (PD), it was found that when the cell size is small, the island-shaped distribution become smoother as the cell size increased. There is the same tendency for the condition of change in the monomer ratio, the polymer chain length or temperature. As a result, the persistent homology may express the higher-order structure generated by the MD simulation as a descriptor of the polymer MI.

scholarly journals Optimizing Long-Lasting Insecticidal Nets Campaign in Ivory Coast

Logistics ◽  
2020 ◽  
Vol 4 (3) ◽  
pp. 18
Author(s):  
Irineu de Brito ◽  
Silvia Uneddu ◽  
Emma Maspero ◽  
Paulo Gonçalves
Keyword(s):  
Network Flow ◽  
Ivory Coast ◽  
Optimal Transport ◽  
Cost Effective ◽  
Mixed Integer ◽  
Efficient Manner ◽  
Humanitarian Organizations ◽  
Mosquito Nets ◽  
Long Lasting Insecticidal Nets ◽  
Health Districts

This research supports the United Nations Children’s Fund’s (UNICEF) conceptualization, planning and implementation of a campaign for distribution of more than 12 million mosquito nets in Ivory Coast. Procured from four different suppliers in Asia, the nets were transported to the two ports in Ivory Coast before being pre-positioned at 71 Health Districts across the country, a mixed integer network flow model identifies optimal transport options. The process of modeling and the model developed in this paper brought a significant understanding of the problem and, consequently, a reduction in the overall procurement and logistics costs. The implications of using mathematical modeling by practitioners as a tool which contributes to solve humanitarian logistics problems are significant. Mathematical models, like linear programming, can greatly support overall decision-making within humanitarian organizations by helping to ensure that limited resources are used in the most cost-effective and efficient manner. However, it is important to ensure consultations with and involvement by on the ground practitioners to ensure developed solutions assessed to fit the operating context before being implemented.

scholarly journals Vulnerability Identification of Hajiabad Plain Aquifer: The DRASTIC Model and the GIS-Based Fuzzy Logic Method

2021 ◽  
Vol 14 ◽  
pp. 117862212110484
Author(s):  
Mehrdad Hassanzadeh ◽  
Mehdi Momeni Reghabadi ◽  
Amir Robati
Keyword(s):  
Fuzzy Logic ◽  
Water Samples ◽  
Groundwater Resources ◽  
Fuzzy Optimization ◽  
Optimization Methods ◽  
Aquifer Vulnerability ◽  
Optimal Method ◽  
Drastic Model ◽  
Vulnerability Maps ◽  
Bandar Abbas

Hajiabad plain with an area of about 158 km2 is located about 160 km north of Bandar Abbas in Iran. Due to the significance of this plain in terms of agricultural and drinking water supply in the region and the declining groundwater level in the region, the withdrawal of water resources has been prohibited in recent years. The purpose of this study is to determine the vulnerability of the aquifer using the DRASTIC model and the optimal method of fuzzy logic as well as the drastic method calibrated with nitrate. Finally, the final vulnerability maps were calibrated with EC values. In order to investigate the hydrogeochemical properties of groundwater resources of the plain, 26 water samples were collected from designated points in different periods of the water year 2018. Water samples were analyzed in Hormozgan soil and water laboratory. Also, the results of water sample data analyzed by Hormozgan Regional Water Organization were used. Assessment of aquifer vulnerability based on vulnerability models showed that the east and parts of the center of the plain were subject to the highest vulnerability, while the southern, southwestern, and northern slopes of the plain were of the lowest vulnerability. The determined coefficients between nitrate and DRASTIC vulnerability models and fuzzy optimization were estimated to be 0.41 and 0.36, respectively. Nitrate concentration validation demonstrated that the vulnerabilities of Hajiabad plain aquifer were almost similar under both drastic model and fuzzy optimization methods.

scholarly journals Modelling sediment clasts transport during landscape evolution

2015 ◽  
Vol 3 (4) ◽  
pp. 1221-1254 ◽  
Author(s):  
S. Carretier ◽  
P. Martinod ◽  
M. Reich ◽  
Y. Godderis
Keyword(s):  
Cell Size ◽  
Landscape Evolution ◽  
Transport Rate ◽  
Time Step ◽  
Size Dependent ◽  
Scattering Rate ◽  
Local Erosion ◽  
Model Cell ◽  
Scattering Time ◽  
Grain Properties

Abstract. Over thousands to millions of years, the landscape evolution is predicted by models based on fluxes of eroded, transported and deposited material. The laws describing these fluxes, corresponding to averages over many years, are difficult to prove with the available data. On the other hand, sediment dynamics are often tackled by studying the distribution of certain grain properties in the field (e.g. heavy metals, detrial zircons, 10Be in gravel, magnetic tracers, etc.). There is a gap between landscape evolution models based on fluxes and these field data on individual clasts, which prevent the latter from being used to calibrate the former. Here we propose an algorithm coupling the landscape evolution with mobile clasts. Our landscape evolution model predicts local erosion, deposition and transfer fluxes resulting from hillslope and river processes. Clasts of any size are initially spread in the basement and are detached, moved and deposited according to probabilities using these fluxes. Several river and hillslope laws are studied. Although the resulting mean transport rate of the clasts does not depend on the time step or the model cell size, our approach is limited by the fact that their scattering rate is cell-size dependent. Nevertheless, both their mean transport rate and the shape of the scattering-time curves fit the predictions. Different erosion-transport laws generate different clast movements. These differences show that studying the tracers in the field may provide a way to establish these laws on the hillslopes and in the rivers. Possible applications include the interpretation of cosmogenic nuclides in individual gravel deposits, provenance analyses, placers, sediment coarsening or fining, the relationship between magnetic tracers in rivers and the river planform, and the tracing of weathered sediment.

The Research of Dynamic Optimization Method on Automobile Shock Absorption Twist Bar Spring Design

2009 ◽  
Vol 16-19 ◽  
pp. 415-419
Author(s):  
Gui Qiu Song
Keyword(s):  
Dynamic Optimization ◽  
Optimization Design ◽  
Optimization Methods ◽  
Optimization Method ◽  
Random Load ◽  
Optimal Method ◽  
New Approach ◽  
Recent Developments ◽  
Spring System ◽  
Automobile Components

This paper presents recent developments in the study of optimization methods for industrial product design, and provides a method of dynamic optimization design to calculate the optimal loading property of automobile twist bar spring system. This is a different approach to traditional systems that is based on dynamic and random load, applying the basic theory and methods of dynamic design, according to the multi-goal characteristic of automobile twist bar spring. This paper presents a thorough analysis dynamic quadratic fuzzy optimal method of double-goal and the method to determine paper optimal gene. This method is used to automobile twist bar spring design, the result shows that the ability of spring loading is improved; the weight of structure is reduced. The new approach makes the vibration absorbing system more reliable and comfortable. The results presented in this paper are not only applicable to automobile twist bar spring systems but all systems that possess dynamic, random and fuzzy characteristics. This work finds applications in automobile components design and dynamic character analysis.

scholarly journals Static Risk-Based Group Testing Schemes Under Imperfectly Observable Risk

2020 ◽  
Vol 10 (4) ◽  
pp. 361-390
Author(s):  
Hrayer Aprahamian ◽  
Ebru K. Bish ◽  
Douglas R. Bish
Keyword(s):  
Network Flow ◽  
Group Testing ◽  
High Dimensional ◽  
Chlamydia Screening ◽  
Efficient Manner ◽  
Flow Problems ◽  
Underlying Network ◽  
Almost All ◽  
The Impact ◽  
Static Risk

Testing multiple subjects within a group, with a single test applied to the group (i.e., group testing), is an important tool for classifying populations as positive or negative for a specific binary characteristic in an efficient manner. We study the design of easily implementable, static group testing schemes that take into account operational constraints, heterogeneous populations, and uncertainty in subject risk, while considering classification accuracy- and robustness-based objectives. We derive key structural properties of optimal risk-based designs and show that the problem can be formulated as network flow problems. Our reformulation involves computationally expensive high-dimensional integrals. We develop an analytical expression that eliminates the need to compute high-dimensional integrals, drastically improving the tractability of constructing the underlying network. We demonstrate the impact through a case study on chlamydia screening, which leads to the following insights: (1) Risk-based designs are shown to be less expensive, more accurate, and more robust than current practices. (2) The performance of static risk-based schemes comprised of only two group sizes is comparable to those comprised of many group sizes. (3) Static risk-based schemes are an effective alternative to more complicated dynamic schemes. (4) An expectation-based formulation captures almost all benefits of a static risk-based scheme.

Analytical Target Cascading Method on Braking System Characteristics Optimization

2013 ◽  
Vol 307 ◽  
pp. 9-13
Author(s):  
Hsin Guan ◽  
Wei Tuo Hao ◽  
Jun Zhan ◽  
Xin Li
Keyword(s):  
Optimization Methods ◽  
Brake System ◽  
Analytical Target Cascading ◽  
Optimal Method ◽  
Master Cylinder ◽  
Braking System ◽  
Target Cascading ◽  
High Degree ◽  
System Characteristics

Because of the Limitations and shortcomings of the traditional multi-disciplinary optimization methods, this paper presents a useful optimal method named Analytical Target Cascading (ATC) for braking system characteristics optimization. The deceleration and pedal sense are chosen as the design targets. Brake system is divided into 4 subsystems: pedal, vacuum booster, master cylinder, brake. The optimization results show that ATC has a high degree of accuracy.

scholarly journals Neural-network-based simulation-optimization model for water allocation planning at basin scale

2008 ◽  
Vol 10 (4) ◽  
pp. 331-343 ◽  
Author(s):  
M. Shourian ◽  
S. Jamshid Mousavi ◽  
M. B. Menhaj ◽  
E. Jabbari
Keyword(s):  
River Basin ◽  
Network Flow ◽  
Model Performance ◽  
Optimization Methods ◽  
Pso Algorithm ◽  
Ann Model ◽  
Modeling Framework ◽  
Operational Variables ◽  
Basin Scale ◽  
Computationally Intensive

Heuristic search techniques are highly flexible, though they represent computationally intensive optimization methods that may require thousands of evaluations of expensive objective functions. This paper integrates MODSIM, a generalized river basin network flow model, a particle swarm optimization (PSO) algorithm and artificial neural networks into a modeling framework for optimum water allocations at basin scale. MODSIM is called in the PSO model to simulate a river basin system operation and to evaluate the fitness of each set of selected design and operational variables with respect to the model's objective function, which is the minimization of the system's design and operational cost. Since the direct incorporation of MODSIM into a PSO algorithm is computationally prohibitive, an ANN model as a meta-model is trained to approximate the MODSIM modeling tool. The resulting model is used in the problem of optimal design and operation of the upstream Sirvan river basin in Iran as a case study. The computational efficiency of the model makes it possible to analyze the model performance through changing its parameters so that better solutions are obtained compared to those of the original PSO–MODSIM model.

scholarly journals A Comparison of Grid Quality of Optimized Spherical Hexagonal–Pentagonal Geodesic Grids

2005 ◽  
Vol 133 (10) ◽  
pp. 2817-2833 ◽  
Author(s):  
Hiroaki Miura ◽  
Masahide Kimoto
Keyword(s):  
Common Ground ◽  
Optimization Methods ◽  
Optimization Method ◽  
Numerical Schemes ◽  
Optimal Method ◽  
Grid Optimization

Abstract Construction and optimization methods of spherical hexagonal–pentagonal geodesic grids are investigated. The objective is to compare grid structures on common ground. The distinction between two types of hexagonal–pentagonal grids is made. Three conventional grid optimization methods are summarized. In addition, three new optimization methods are proposed. Six desirable conditions for an ideal grid are described, and the grid optimization methods are organized in view of such conditions. Interval uniformity, area uniformity, isotropy, and bisection of cell faces are systematically investigated for optimized grids. There are compensations of preferable grid features in each optimization method, and an optimal method cannot be decided based only on the research of grid features. It is suggested that grid optimization methods should be selected based on research of numerical schemes.

scholarly journals Using phylogeny to model cell size evolution in marine and freshwater diatoms

2014 ◽  
Vol 59 (1) ◽  
pp. 79-86 ◽  
Author(s):  
Teofil Nakov ◽  
Edward C. Theriot ◽  
Andrew J. Alverson
Keyword(s):  
Cell Size ◽  
Size Evolution ◽  
Freshwater Diatoms ◽  
Model Cell
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