scholarly journals Is Satisfiability of Quantified Bit-Vector Formulas Stable Under Bit-Width Changes? (Experimental Paper)

10.29007/spnx ◽  
2018 ◽  
Author(s):  
Martin Jonáš ◽  
Jan Strejček
Keyword(s):  
Improve Performance ◽  
Practical Applications ◽  
Software Bugs ◽  
Smt Solvers ◽  
Starting Point ◽  
Bit Vector

In general, deciding satisfiability of quantified bit-vector formulas becomes harder with increasing maximal allowed bit-width of variables and constants. However, this does not have to be the case for formulas that come from practical applications. For example, software bugs often do not depend on the specific bit-width of the program variables and would manifest themselves also with much lower bit-widths. We experimentally evaluate this thesis and show that satisfiability of the vast majority of quantified bit-vector formulas from the smt-lib repository remains the same even after reducing bit-widths of variables to a very small number. This observation may serve as a starting-point for development of heuristics or other techniques that can improve performance of smt solvers for quantified bit-vector formulas.

scholarly journals CFD Analysis of Urban Canopy Flows Employing the V2F Model: Impact of Different Aspect Ratios and Relative Heights

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Fabio Nardecchia ◽  
Annalisa Di Bernardino ◽  
Francesca Pagliaro ◽  
Paolo Monti ◽  
Giovanni Leuzzi ◽  
...  
Keyword(s):  
Flow Field ◽  
Water Channel ◽  
Flow Regimes ◽  
Two Dimensional ◽  
Mean Flow ◽  
Ansys Fluent ◽  
Practical Applications ◽  
Aspect Ratios ◽  
Starting Point ◽  
Step Down

Computational fluid dynamics (CFD) is currently used in the environmental field to simulate flow and dispersion of pollutants around buildings. However, the closure assumptions of the turbulence usually employed in CFD codes are not always physically based and adequate for all the flow regimes relating to practical applications. The starting point of this work is the performance assessment of the V2F (i.e., v2¯ − f) model implemented in Ansys Fluent for simulating the flow field in an idealized array of two-dimensional canyons. The V2F model has been used in the past to predict low-speed and wall-bounded flows, but it has never been used to simulate airflows in urban street canyons. The numerical results are validated against experimental data collected in the water channel and compared with other turbulence models incorporated in Ansys Fluent (i.e., variations of both k-ε and k-ω models and the Reynolds stress model). The results show that the V2F model provides the best prediction of the flow field for two flow regimes commonly found in urban canopies. The V2F model is also employed to quantify the air-exchange rate (ACH) for a series of two-dimensional building arrangements, such as step-up and step-down configurations, having different aspect ratios and relative heights of the buildings. The results show a clear dependence of the ACH on the latter two parameters and highlight the role played by the turbulence in the exchange of air mass, particularly important for the step-down configurations, when the ventilation associated with the mean flow is generally poor.

scholarly journals Automation of the Leonardo da Vinci Machines

Machines ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 53
Author(s):  
Maide Bucolo ◽  
Arturo Buscarino ◽  
Carlo Famoso ◽  
Luigi Fortuna ◽  
Salvina Gagliano
Keyword(s):  
Automatic Control ◽  
Da Vinci ◽  
Low Cost ◽  
Classical Mechanics ◽  
Leonardo Da Vinci ◽  
Advanced Technology ◽  
Mechanical Equipment ◽  
Practical Applications ◽  
Main Research ◽  
Starting Point

Leonardo da Vinci inventions and projects represent an intriguing starting point to remark the concept that innovation must be considered as a continuous route towards evolution in history. Some of the particular ideas and innovations presented by Leonardo da Vinci led us to formulate a link with automatic control. Selected models of the Leonardo da Vinci machines are presented in this paper, taking strictly into account the original mechanical schemes and working principles, but introducing modern low-cost control equipment, emphasizing the role of automatic control and that of electronic control devices, such as microcontrollers, sensors, and communication devices, to completely automate the Leonardo da Vinci machines. The approach outlined in the paper can be applied not only to other Leonardo machines but also to other mechanical equipment not necessarily designed by Leonardo da Vinci. Moreover, it is useful to remark that the approach followed in this paper can be very important also to introduce students, leading by example, to concepts typical of automation and for assisting in learning, keeping in mind the practical applications of advanced automation principles. The main research task of this paper is proving the efficacy of modern digital control techniques and teleoperation in strongly classical mechanical Leonardo machines, remarking that the projects of Leonardo are prompt to be efficiently controlled. This task could not be explored by Leonardo himself due to the lack of control technology. Moreover, the paper is addressed also to stimulate the young generations of engineers in joining classical mechanics with advanced technology. Therefore, the paper is also devoted to give focus on the fact that the Leonardo machines encompass all the key aspects of modern system engineering.

scholarly journals Applications of variable-order fractional operators: a review

2020 ◽  
Vol 476 (2234) ◽  
pp. 20190498 ◽  
Author(s):  
Sansit Patnaik ◽  
John P. Hollkamp ◽  
Fabio Semperlotti
Keyword(s):  
Transport Processes ◽  
Point Of View ◽  
Variable Order ◽  
Fractional Operators ◽  
Mathematical Concepts ◽  
Physical Systems ◽  
Practical Applications ◽  
Starting Point ◽  
Made In ◽  
Real World Problems

Variable-order fractional operators were conceived and mathematically formalized only in recent years. The possibility of formulating evolutionary governing equations has led to the successful application of these operators to the modelling of complex real-world problems ranging from mechanics, to transport processes, to control theory, to biology. Variable-order fractional calculus (VO-FC) is a relatively less known branch of calculus that offers remarkable opportunities to simulate interdisciplinary processes. Recognizing this untapped potential, the scientific community has been intensively exploring applications of VO-FC to the modelling of engineering and physical systems. This review is intended to serve as a starting point for the reader interested in approaching this fascinating field. We provide a concise and comprehensive summary of the progress made in the development of VO-FC analytical and computational methods with application to the simulation of complex physical systems. More specifically, following a short introduction of the fundamental mathematical concepts, we present the topic of VO-FC from the point of view of practical applications in the context of scientific modelling.

Explicit Analytical Solutions for a Complete Set of the Eshelby Tensors of an Ellipsoidal Inclusion

2016 ◽  
Vol 83 (12) ◽  
Author(s):  
Xiaoqing Jin ◽  
Ding Lyu ◽  
Xiangning Zhang ◽  
Qinghua Zhou ◽  
Qian Wang ◽  
...  
Keyword(s):  
Deformation Gradient ◽  
Elastic Field ◽  
Analytical Form ◽  
Ellipsoidal Inclusion ◽  
Normal Vector ◽  
Full Field ◽  
Practical Applications ◽  
Starting Point ◽  
Complete Set ◽  
Outward Unit

The celebrated solution of the Eshelby ellipsoidal inclusion has laid the cornerstone for many fundamental aspects of micromechanics. A well-known difficulty of this classical solution is to determine the elastic field outside the ellipsoidal inclusion. In this paper, we first analytically present the full displacement field of an ellipsoidal inclusion subjected to uniform eigenstrain. It is demonstrated that the displacements inside inclusion are linearly related to the coordinates and continuous across the interface of inclusion and matrix. The exterior displacement, which is less detailed in existing literatures, may be expressed in a more compact, explicit, and simpler form through utilizing the outward unit normal vector of an auxiliary confocal ellipsoid. Other than many practical applications in geological engineering, the displacement solution can be a convenient starting point to derive the deformation gradient, and subsequently in a straightforward manner to accomplish the full-field solutions of the strain and stress. Following Eshelby's definition, a complete set of the Eshelby tensors corresponding to the displacement, deformation gradient, strain, and stress are expressed in explicit analytical form. Furthermore, the jump conditions to quantify the discontinuities across the interface are discussed and a benchmark problem is provided to validate the present formulation.

scholarly journals Wits: An Efficient Wi-Fi Based Indoor Positioning and Tracking System

2021 ◽  
Vol 14 (1) ◽  
pp. 19
Author(s):  
Li-Ping Tian ◽  
Liang-Qin Chen ◽  
Zhi-Meng Xu ◽  
Zhizhang (David) Chen
Keyword(s):  
Tracking System ◽  
Indoor Positioning ◽  
Doppler Velocity ◽  
Channel State ◽  
Time Intervals ◽  
Practical Applications ◽  
Mean Error ◽  
Starting Point ◽  
Motion Speed ◽  
The Mean

With the development of wireless communication technology, indoor tracking technology has been rapidly developed. Wits presents a new indoor positioning and tracking algorithm with channel state information of Wi-Fi signals. Wits tracks using motion speed. Firstly, it eliminates static path interference and calibrates the phase information. Then, the maximum likelihood of the phase is used to estimate the radial Doppler velocity of the target. Experiments were conducted, and two sets of receiving antennas were used to determine the velocity of a human. Finally, speed and time intervals were used to track the target. Experimental results show that Wits can achieve the mean error of 0.235 m in two different environments with a known starting point. If the starting point is unknown, the mean error is 0.410 m. Wits has good accuracy and efficiency for practical applications.

scholarly journals Quantitative Indicators for Country-Level Innovation Ecosystems

2018 ◽  
Author(s):  
Michael Hogan ◽  
Michael Gallaher
Keyword(s):  
Growth Potential ◽  
Middle Income ◽  
Practical Applications ◽  
Country Level ◽  
Data Limitations ◽  
Starting Point ◽  
Key Factor ◽  
Changes Over Time ◽  
Future Work ◽  
Quantitative Indicators

Innovation has been shown to be a key factor in determining a country’s competitiveness and economic growth potential. Through investments in education and research and development, many developing countries have tried to avoid the “middle income trap” of stagnation by working to create high-value employment opportunities. To better understand country-level readiness to innovate, we have compiled a set of publicly available data indicators and created a data tool to illustrate innovation capabilities and infrastructure by country. Our approach builds on and advances existing national innovation metrics by constructing transparent, publicly sourced indicators that emphasize changes over time and interrelationships between different indicators, as opposed to creating simple indices across groups of indicators. This occasional paper is targeted to an applied audience, explaining the methods used to assemble the data, an overview of the indicators, practical applications of the data, summary statistics, and data limitations. The data are not intended to be a tool for providing answers about innovation, but rather a starting point for future work including market landscaping, country-level diagnostics, and qualitative protocols for research.

scholarly journals On the Complexity of Fixed-Size Bit-Vector Logics with Binary Encoded Bit-Width

10.29007/cvnz ◽  
2018 ◽  
Author(s):  
Gergely Kovásznai ◽  
Andreas Fröhlich ◽  
Armin Biere
Keyword(s):  
Point Of View ◽  
Satisfiability Modulo Theories ◽  
Theoretical Point ◽  
Fixed Size ◽  
Practical Applications ◽  
Binary Encoding ◽  
Complexity Results ◽  
Bit Vector

Bit-precise reasoning is important for many practical applications ofSatisfiability Modulo Theories (SMT). In recent years efficient approachesfor solving fixed-size bit-vector formulas have been developed. Fromthe theoretical point of view, only few results on the complexity offixed-size bit-vector logics have been published. In this paper we showthat some of these results only hold if unary encoding on the bit-width ofbit-vectors is used. We then consider fixed-size bit-vector logics withbinary encoded bit-width and establish new complexity results. Our proofsshow that binary encoding adds more expressiveness to bit-vector logics,e.g. it makes fixed-size bit-vector logic even without uninterpretedfunctions nor quantication NExpTime-complete. We also show that undercertain restrictions the increase of complexity when using binary encodingcan be avoided.

scholarly journals A Methodology for the Design of RTC Strategies for Combined Sewer Networks

Water ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1675 ◽  
Author(s):  
Stefan Kroll ◽  
Marjoleine Weemaes ◽  
Jan Van Impe ◽  
Patrick Willems
Keyword(s):  
Control Strategies ◽  
Real Life ◽  
Control Algorithms ◽  
Real Time Control ◽  
Practical Applications ◽  
Time Control ◽  
Drainage Networks ◽  
Starting Point ◽  
Combined Sewer ◽  
Large Case

While real-time control (RTC) is considered an established means of performance improvement for existing urban drainage networks, practical applications are frequently only documented for large case studies, and many operators are still reluctant to adopt RTC into their own systems. The purpose of the presented study is to highlight the potential of RTC also for smaller networks by the example of five representative catchments in Flanders, Belgium, and to demonstrate a novel methodology for the automated design of control strategies. This method analyses a given sewer network for the identification of suitable existing and new control locations. The gathered information is used in a second step for the design of control algorithms according to generic control concepts documented in the literature, such as e.g., “Equal Filling Degree”. The resulting RTC strategy uses sensible default parameters, and can form a starting point for further refinement through optimization or manual tuning. With a modelled total combined sewer overflow volume reduction of 20% to 50%, the created strategies showed generally good performance for the tested catchments. The method proved to be applicable for all tested networks. Its use for the real-life implementation of RTC is currently under way for 10 other Flemish cases.

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