scholarly journals Modeling and Algorithmic Approaches to Constitutively-Complex, Microstructured Fluids

2014 ◽  
Author(s):  
Gregory H. Miller ◽  
Gregory Forest
Keyword(s):  
Algorithmic Approaches ◽  
Microstructured Fluids

Cryo-TEM of amphiphilic polymer and amphiphile/polymer solutions

1993 ◽  
Vol 51 ◽  
pp. 876-877
Author(s):  
Yeshayahu Talmon
Keyword(s):  
Microstructural Characterization ◽  
Building Blocks ◽  
Quantitative Information ◽  
Physical Models ◽  
Specimen Preparation ◽  
Time Resolved ◽  
Temperature Changes ◽  
Temperature And Humidity ◽  
Microstructured Fluids ◽  
Air Streams

To achieve complete microstructural characterization of self-aggregating systems, one needs direct images in addition to quantitative information from non-imaging, e.g., scattering or Theological measurements, techniques. Cryo-TEM enables us to image fluid microstructures at better than one nanometer resolution, with minimal specimen preparation artifacts. Direct images are used to determine the “building blocks” of the fluid microstructure; these are used to build reliable physical models with which quantitative information from techniques such as small-angle x-ray or neutron scattering can be analyzed.To prepare vitrified specimens of microstructured fluids, we have developed the Controlled Environment Vitrification System (CEVS), that enables us to prepare samples under controlled temperature and humidity conditions, thus minimizing microstructural rearrangement due to volatile evaporation or temperature changes. The CEVS may be used to trigger on-the-grid processes to induce formation of new phases, or to study intermediate, transient structures during change of phase (“time-resolved cryo-TEM”). Recently we have developed a new CEVS, where temperature and humidity are controlled by continuous flow of a mixture of humidified and dry air streams.

scholarly journals MFIX-Exa: A path toward exascale CFD-DEM simulations

2021 ◽  
pp. 109434202110092
Author(s):  
Jordan Musser ◽  
Ann S Almgren ◽  
William D Fullmer ◽  
Oscar Antepara ◽  
John B Bell ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Element Model ◽  
Discrete Element Model ◽  
Software Framework ◽  
Chemical Reactors ◽  
Software Infrastructure ◽  
Fundamental Physics ◽  
Dem Simulations ◽  
Algorithmic Approaches

MFIX-Exa is a computational fluid dynamics–discrete element model (CFD-DEM) code designed to run efficiently on current and next-generation supercomputing architectures. MFIX-Exa combines the CFD-DEM expertise embodied in the MFIX code—which was developed at NETL and is used widely in academia and industry—with the modern software framework, AMReX, developed at LBNL. The fundamental physics models follow those of the original MFIX, but the combination of new algorithmic approaches and a new software infrastructure will enable MFIX-Exa to leverage future exascale machines to optimize the modeling and design of multiphase chemical reactors.

Algorithmic approaches to redesigning tcam-based systems

2008 ◽  
Vol 36 (1) ◽  
pp. 467-468 ◽  
Author(s):  
Chad R. Meiners ◽  
Alex X. Liu ◽  
Eric Torng
Keyword(s):  
Algorithmic Approaches

scholarly journals Minimum cost network flows: Problems, algorithms, and software

2013 ◽  
Vol 23 (1) ◽  
pp. 3-17 ◽  
Author(s):  
Angelo Sifaleras
Keyword(s):  
Network Flow ◽  
Flow Problem ◽  
Network Flows ◽  
Minimum Cost ◽  
Network Flow Problem ◽  
Software Packages ◽  
Wide Range ◽  
Solution Methods ◽  
Minimum Cost Network Flow ◽  
Algorithmic Approaches

We present a wide range of problems concerning minimum cost network flows, and give an overview of the classic linear single-commodity Minimum Cost Network Flow Problem (MCNFP) and some other closely related problems, either tractable or intractable. We also discuss state-of-the-art algorithmic approaches and recent advances in the solution methods for the MCNFP. Finally, optimization software packages for the MCNFP are presented.

scholarly journals A framework for automatically visualizing and recommending efficient routes

2019 ◽  
Vol 2 ◽  
pp. 1-8
Author(s):  
Stefan Fuest ◽  
Monika Sester
Keyword(s):  
Traffic Management ◽  
Human Perception ◽  
Urban Environments ◽  
Altruistic Behavior ◽  
Traffic Density ◽  
The Road ◽  
Geographic Space ◽  
Route Choice Behavior ◽  
Actual Shape ◽  
Algorithmic Approaches

<p><strong>Abstract.</strong> Due to an increasing traffic density in urban environments, the traffic management as well as the society needs to face various problems including congestion, air pollution or a higher probability of accidents. Therefore, it is getting more important to make road users aware of efficient route alternatives to obtain a better distribution of the traffic flow. Since the time for making route decisions is usually limited, the visualization of the information, which should be conveyed, needs to be prepared in a very clear and easily understandable format. In this approach, we propose a framework for automatically visualizing route efficiency based on various environmentally relevant scenarios. Our methods used to create the map visualizations are based on human perception of space, in order to communicate routes and traffic-related situations more intuitively. That is, humans are assumed to mentally abstract the geographic space using various types of distortions rather than perceiving the environment in its actual shape. Based on these concepts, we argue that a perception-based representation of the route, as well as the visual communication of temporary disturbances may not only simplify the navigation process, but also supports an awareness for the current traffic dynamics, which thus may influence route choice behavior towards a more altruistic behavior. In this paper, we further present two algorithmic approaches for automatically abstracting the geometry of a route in more detail, using cartographic generalization techniques - to present the road network in a way, how it might be perceived based on a certain traffic situation.</p>

scholarly journals Let Trajectories Speak Out the Traffic Bottlenecks

2022 ◽  
Vol 13 (1) ◽  
pp. 1-21
Author(s):  
Hui Luo ◽  
Zhifeng Bao ◽  
Gao Cong ◽  
J. Shane Culpepper ◽  
Nguyen Lu Dang Khoa
Keyword(s):  
Traffic Volume ◽  
Trajectory Data ◽  
Trade Offs ◽  
Bottleneck Identification ◽  
Spread Model ◽  
Efficiency And Effectiveness ◽  
Historical Trajectory ◽  
Algorithmic Approaches ◽  
Compare And Contrast ◽  
Road Segments

Traffic bottlenecks are a set of road segments that have an unacceptable level of traffic caused by a poor balance between road capacity and traffic volume. A huge volume of trajectory data which captures realtime traffic conditions in road networks provides promising new opportunities to identify the traffic bottlenecks. In this paper, we define this problem as trajectory-driven traffic bottleneck identification : Given a road network R , a trajectory database T , find a representative set of seed edges of size K of traffic bottlenecks that influence the highest number of road segments not in the seed set. We show that this problem is NP-hard and propose a framework to find the traffic bottlenecks as follows. First, a traffic spread model is defined which represents changes in traffic volume for each road segment over time. Then, the traffic diffusion probability between two connected segments and the residual ratio of traffic volume for each segment can be computed using historical trajectory data. We then propose two different algorithmic approaches to solve the problem. The first one is a best-first algorithm BF , with an approximation ratio of 1-1/ e . To further accelerate the identification process in larger datasets, we also propose a sampling-based greedy algorithm SG . Finally, comprehensive experiments using three different datasets compare and contrast various solutions, and provide insights into important efficiency and effectiveness trade-offs among the respective methods.

scholarly journals Minimization in Cooperative Response to Failing Database Queries

1997 ◽  
Vol 06 (02) ◽  
pp. 95-149 ◽  
Author(s):  
Parke Godfrey
Keyword(s):  
Optimal Algorithm ◽  
Simple Algorithm ◽  
Search Space ◽  
Database Systems ◽  
Identification Problems ◽  
Database Queries ◽  
The Past ◽  
Cause Of Failure ◽  
Algorithmic Approaches ◽  
Answer Set

When a query fails, it is more cooperative to identify the cause of failure, rather than just to report the empty answer set. When there is not a cause per se for the query's failure, it is then worthwhile to report the part of the query which failed. To identify a Minimal Failing Subquery (MFS) of the query is the best way to do this. (This MFS is not unique; there may be many of them.) Likewise, to identify a Maximal Succeeding Subquery (XSS) can help a user to recast a new query that leads to a non-empty answer set. Database systems do not provide the functionality of these types of cooperative responses. This may be, in part, because algorithmic approaches to finding the MFSs and the XSSs to a failing query are not obvious. The search space of subqueries is large. Despite work on MFSs in the past, the algorithmic complexity of these identification problems had remained uncharted. This paper shows the complexity profile of MFS and XSS identification. It is shown that there exists a simple algorithm for finding an MFS or an XSS by asking N subsequent queries, in which N is the length of the query. To find more MFSs (or XSSs) can be hard. It is shown that to find N MFSs (or XSSs) is NP-hard. To find k MFSs (or XSSs), for a fixed k, remains polynomial. An optimal algorithm for enumerating MFSs and XSSs, ISHMAEL, is developed and presented. The algorithm has ideal performance in enumeration, finding the first answers quickly, and only decaying toward intractability in a predictable manner as further answers are found. The complexity results and the algorithmic approaches given in this paper should allow for the construction of cooperative facilities which identify MFSs and XSSs for database systems. These results are relevant to a number of problems outside of databases too, and may find further application.

scholarly journals Algorithmic approaches to the diagnosis of gallbladder intraluminal lesions on ultrasonography

2018 ◽  
Vol 81 (4) ◽  
pp. 297-304 ◽  
Author(s):  
Chia-Hung Wu ◽  
Yukun Luo ◽  
Xiang Fei ◽  
Yi-Hong Chou ◽  
Hong-Jen Chiou ◽  
...  
Keyword(s):  
Algorithmic Approaches

A Distributed Approach for Accessibility and Maintainability Check With a Manikin

1999 ◽  
Author(s):  
Patrick Chedmail ◽  
Christophe Le Roy
Keyword(s):  
Virtual Reality ◽  
Original Method ◽  
Direct Manipulation ◽  
Agent Architecture ◽  
Constrained Optimisation ◽  
Cluttered Environment ◽  
Distributed Approach ◽  
Multi Agent ◽  
The One ◽  
Algorithmic Approaches

Abstract The validation of the accessibility, maintainability, mounting/dismantle simulation in a cluttered environment is a key problem during the design process of a mechanical system. On the one hand research in path planning lead to automatic trajectory definition. These systems are really efficient for simple problems. On the other hand direct manipulation is possible thanks to robotic CAD systems. Another direct manipulation is possible with common virtual reality tools that allow the designer immersion in a whole mechanical environment. In such an environment the designer can handle an object in order to check its accessibility. Thanks to the use of a multi-agent architecture we greatly improve the effectiveness of virtual reality tools while coupling algorithmic approaches and direct manipulation. This original method is a solution of a multi-criteria constrained optimisation problem. Theoretical and practical aspects are presented.

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