scholarly journals Optimization Modulo the Theories of Signed Bit-Vectors and Floating-Point Numbers

2021 ◽  
Author(s):  
Patrick Trentin ◽  
Roberto Sebastiani
Keyword(s):  
Floating Point ◽  
The Novel ◽  
Objective Functions ◽  
Linear Arithmetic ◽  
Novel Approach ◽  
Optimization Modulo Theories ◽  
Important Extension ◽  
Novel Concept ◽  
First Time ◽  
Floating Point Numbers

AbstractOptimization modulo theories (OMT) is an important extension of SMT which allows for finding models that optimize given objective functions, typically consisting in linear-arithmetic or Pseudo-Boolean terms. However, many SMT and OMT applications, in particular from SW and HW verification, require handling bit-precise representations of numbers, which in SMT are handled by means of the theory of bit-vectors ($${{\mathcal {B}}}{{\mathcal {V}}}$$ B V ) for the integers and that of floating-point numbers ($$\mathcal {FP}$$ FP ) for the reals respectively. Whereas an approach for OMT with (unsigned) $${{\mathcal {B}}}{{\mathcal {V}}}$$ B V objectives has been proposed by Nadel & Ryvchin, unfortunately we are not aware of any existing approach for OMT with $$\mathcal {FP}$$ FP objectives. In this paper we fill this gap, and we address for the first time $$\text {OMT}$$ OMT with $$\mathcal {FP}$$ FP objectives. We present a novel OMT approach, based on the novel concept of attractor and dynamic attractor, which extends the work of Nadel and Ryvchin to work with signed-$${{\mathcal {B}}}{{\mathcal {V}}}$$ B V objectives and, most importantly, with $$\mathcal {FP}$$ FP objectives. We have implemented some novel $$\text {OMT}$$ OMT procedures on top of OptiMathSAT and tested them on modified problems from the SMT-LIB repository. The empirical results support the validity and feasibility of our novel approach.

Edge controller – a small UAVs distributed avionics paradigm

2019 ◽  
Vol 92 (2) ◽  
pp. 229-236
Author(s):  
Svetoslav Zabunov ◽  
Roumen Nedkov
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Design Methodology ◽  
The Novel ◽  
Functional Requirements ◽  
New Paradigm ◽  
Content Type ◽  
Novel Approach ◽  
Novel Concept ◽  
Practical Implications ◽  
Structure And Design

Purpose This paper aims to reveal the authors’ conceptual and experimental work on an innovative avionics paradigm for small unmanned aerial vehicles (UAVs). Design/methodology/approach This novel approach stipulates that, rather than being centralized at the autopilot, control of avionics devices is instead distributed among controllers – spread over the airframe span, in response to avionics devices’ natural location requirements. The latter controllers are herein referred to as edge controllers by the first author. Findings The edge controller manifests increased efficiency in a number of functions, some of which are unburdened from the autopilot. The edge controller establishes a new paradigm of structure and design of small UAVs avionics such that any functionality related to the periphery of the airframe is implemented in the controller. Research limitations/implications The research encompasses a workbench prototype testing on a breadboard, as the presented idea is a novel concept. Further, another test has been conducted with four controllers mounted on a quadcopter; results from the vertical attitude sustenance are disclosed herein. Practical implications The motivation behind developing this paradigm was the need to position certain avionics devices at different locations on the airframe. Due to their inherent functional requirements, most of these devices have hitherto been placed at the periphery of the aircraft construction. Originality/value The current paper describes the novel avionics paradigm, compares it to the standard approach and further reveals two experimental setups with testing results.

A unified approach to Stefan’s problem for spheres and cylinders

1980 ◽  
Vol 373 (1752) ◽  
pp. 131-147 ◽  
Keyword(s):  
Latent Heat ◽  
Asymptotic Theory ◽  
Cylindrical Body ◽  
The Novel ◽  
Sensible Heat ◽  
Unified Approach ◽  
Fusion Temperature ◽  
Molten Material ◽  
Novel Approach ◽  
First Time

The problem of the inward solidification of a spherical or cylindrical body of molten material, initially at its uniform fusion temperature, when the outside is suddenly cooled, is considered. A complete asymptotic theory is developed for the case when the parameter A, which measures the ratio of latent heat to sensible heat of the substance, is large. Uniformly valid approximations to the solution are found everywhere, for all time t*, up to the instant t* = t* e ,at which the material is completely frozen. Though many of the results have been obtained previously, the treatment of the final freezing of the central core as t* -> t* e is new. For the cylinder, the novel approach enables asymptotic solutions to be obtained, when t* t* e , for the first time.

scholarly journals From a Pareto Front to Pareto Regions: A Novel Standpoint for Multiobjective Optimization

Mathematics ◽  
2021 ◽  
Vol 9 (24) ◽  
pp. 3152
Author(s):  
Carine M. Rebello ◽  
Márcio A. F. Martins ◽  
Daniel D. Santana ◽  
Alírio E. Rodrigues ◽  
José M. Loureiro ◽  
...  
Keyword(s):  
Multiobjective Optimization ◽  
Pareto Front ◽  
Optimization Problems ◽  
The Novel ◽  
Particle Swarm Optimizer ◽  
Novel Approach ◽  
Multiobjective Optimization Problems ◽  
Pressure Swing ◽  
Novel Concept

This work presents a novel approach for multiobjective optimization problems, extending the concept of a Pareto front to a new idea of the Pareto region. This new concept provides all the points beyond the Pareto front, leading to the same optimal condition with statistical assurance. This region is built using a Fisher–Snedecor test over an augmented Lagragian function, for which deductions are proposed here. This test is meant to provide an approximated depiction of the feasible operation region while using meta-heuristic optimization results to extract this information. To do so, a Constrained Sliding Particle Swarm Optimizer (CSPSO) was applied to solve a series of four benchmarks and a case study. The proposed test analyzed the CSPSO results, and the novel Pareto regions were estimated. Over this Pareto region, a clustering strategy was also developed and applied to define sub-regions that prioritize one of the objectives and an intermediary region that provides a balance between objectives. This is a valuable tool in the context of process optimization, aiming at assertive decision-making purposes. As this is a novel concept, the only way to compare it was to draw the entire regions of the benchmark functions and compare them with the methodology result. The benchmark results demonstrated that the proposed method could efficiently portray the Pareto regions. Then, the optimization of a Pressure Swing Adsorption unit was performed using the proposed approach to provide a practical application of the methodology developed here. It was possible to build the Pareto region and its respective sub-regions, where each process performance parameter is prioritized. The results demonstrated that this methodology could be helpful in processes optimization and operation. It provides more flexibility and more profound knowledge of the system under evaluation.

Power Augmentation of Heavy Duty and Two-Shaft Small and Medium Capacity Combustion Turbines With Application of Humid Air Injection and Dry Air Injection Technologies

2004 ◽  
Author(s):  
Michael Nakhamkin ◽  
Robert Pelini ◽  
Manu I. Patel ◽  
Ron Wolk
Keyword(s):  
Distributed Generation ◽  
Power Plants ◽  
Combined Cycle ◽  
Air Injection ◽  
The Novel ◽  
Capital Costs ◽  
Dry Air ◽  
Performance Improvements ◽  
Novel Approach ◽  
Novel Concept

This paper presents the latest information on Humid/Dry Air Injection (HAI/DAI) power augmentation technology for Combustion Turbine (CT) and Combined Cycle (CC) power plants. It describes: • The summary of the latest activities on the implementation of HAI and DAI technologies including results of the validations tests conducted on the PG7241 (FA) combustion turbine, and findings of various CT-HAI implementation projects. • The technical background including the latest CT-HAI and CT-DAI concepts resulting in the performance improvements and reduced emissions. • A novel concept for humidification of the injected air that further reduces overall capital costs by 15%. • The novel approach for the power augmentation of two-shaft small and medium capacity CTs with application of HAI and DAI technologies. Two-shaft CTs are widely used for electric power generation, including distributed generation, as well as a variable-speed mechanical driving engine including driving natural gas (NG) pipeline compressors (PC).

scholarly journals A novel approach to assess radial distribution system for optimal sizing of microgrid

2020 ◽  
Vol 17 (3) ◽  
pp. 1618
Author(s):  
Shalaka Chaphekar ◽  
Anjali A. Dharme
Keyword(s):  
Distributed Generation ◽  
Radial Distribution ◽  
Distribution System ◽  
The Novel ◽  
Radial Distribution System ◽  
Novel Approach ◽  
Penetration Ratio ◽  
Daily Energy ◽  
Novel Concept ◽  
The Impact

<p>The performance of Radial Distribution System (RDS) is enhanced by maintaining the appropriate Penetration Ratio (PR) of Distributed generation.  However, it has been observed that Penetration Ratio cannot be useful to analyze the impact of a Microgrid on performance of RDS. Hence a new index ‘Relief Factor’ (RF) is defined in this paper and the impact of Microgrid at different RF is studied. This paper presents an approach to compute daily energy losses variation when Microgrids of varying RF are connected to RDS having different maximum demands.  A methodology has been proposed for finding optimal RF and location of Microgrid.  In addition, the impact of maximum demand of RDS on optimum RF is analyzed. This paper gives the novel concept of assessing the RDS for integration of Microgrid based on maximum demand of RDS as well as Microgrid and sizing of Microgrid based on optimum Relief Factor.</p>

scholarly journals High-performance cellulosic filament fibers prepared via dry-jet wet spinning from ionic liquids

Cellulose ◽  
2021 ◽  
Author(s):  
Marc P. Vocht ◽  
Ronald Beyer ◽  
Patricija Thomasic ◽  
Alexandra Müller ◽  
Antje Ota ◽  
...  
Keyword(s):  
High Performance ◽  
Continuous Process ◽  
Degree Of Polymerization ◽  
Alkali Resistance ◽  
Wet Spinning ◽  
The Novel ◽  
Cellulosic Fibers ◽  
Novel Approach ◽  
First Time

AbstractWe report on a new process for the spinning of high-performance cellulosic fibers. For the first time, cellulose has been dissolved in the ionic liquid (IL) 1-ethyl-3-methylimidazolium octanoate ([C2C1im][Oc]) via a thin film evaporator in a continuous process. Compared to other ILs, [C2C1im][Oc] shows no signs of hydrolysis with water. For dope preparation the degree of polymerization of the pulp was adjusted by electron beam irradiation and determined by viscosimetry. In addition, the quality of the pulp was evaluated by means of alkali resistance. Endless filament fibers have been spun using dry-jet wet spinning and an extruder instead of a spinning pump, which significantly increases productivity. By this approach, more than 1000 m of continuous multifilament fibers have been spun. The novel approach allows for preparing cellulose fibers with high Young's modulus (33 GPa) and unprecedented high tensile strengths up to 45 cN/tex. The high performance of the obtained fibers provides a promising outlook for their application as replacement material for rayon-based tire cord fibers.

A Novel Approach to the Stabilization of Auto-Igniting Flames Within a Gas Turbine Sequential Combustor, Through the Control of Static Temperature Variation Along the Premixing and Flame Zones

2020 ◽  
Author(s):  
K. J. Syed ◽  
A. C. Benim ◽  
E. Pasqualotto ◽  
R. C. Payne
Keyword(s):  
Gas Turbine ◽  
Pressure Loss ◽  
The Novel ◽  
Turbine Stage ◽  
Critical Aspect ◽  
Single Digit ◽  
Pressure Losses ◽  
Hot Gas ◽  
Novel Approach ◽  
Novel Concept

Abstract The present work proposes a novel concept for a sequential burner and combustor that can be located downstream of a first stage combustor or downstream of a turbine stage in the case of a reheat gas turbine. The novel aspect is the method of flame anchoring, which, instead of relying on dump expansion as in the present state-of-the-art, relies on setting up a static temperature gradient through the premixing and flame zones. The advantage of this is that anchoring of the auto-igniting flame is not dependent on fluid mechanic phenomena, and reaction can proceed at rates governed by the chemical kinetics. Under these circumstances, CO can reach its equilibrium in ≪ 1ms, which allows for compactness and the potential of single digit NOx emissions at hot gas temperatures in excess of 2100K. Pressure loss is a critical aspect, as the concept requires flows to be accelerated to high velocities (M∼0.7). However, it is shown that pressure losses can be limited to 4–5%. The concept is evaluated through analytical and 1D approaches, while the feasibility of achieving a design that meets the desired turbulence characteristics at an acceptable pressure loss is demonstrated by way of 3D CFD.

scholarly journals Total Bond Order Density as a Quantum Mechanical Metric for Materials Design: Application to Chalcogenide Crystals

2019 ◽  
Author(s):  
Sahib Hasan ◽  
Khagendra Baral ◽  
Wai-Yim Ching
Keyword(s):  
Bond Order ◽  
Interatomic Interaction ◽  
Materials Design ◽  
First Principles Calculation ◽  
Quantum Mechanical ◽  
The Novel ◽  
Novel Approach ◽  
Optical And Mechanical Properties ◽  
Novel Concept ◽  
Scale Design

Materials design for processing and application requires fundamental understanding of their properties based interatomic interaction. The use of the novel concept of total bond order density (TBOD) as a single quantum mechanical metric to characterize the internal cohesion of a crystal and correlate with the calculated physical properties is particularly appealing. This requires detailed first-principles calculation of the electronic structure, interatomic bonding and related properties. In this article, we use this new concept and apply it to chalcogenide crystals based on data obtained from 25 crystals: Ag2S, Ag2Se, Ag2Te, As2S3, As2Se3, As2Te3, As4Se4, Cu2S, Cu2Se, Cu2Te, Cu4GeS4, Cu2SnS3, Cu2SnSe3, GeS2, GeSe2, Ge4Se9, Sb2S3, Sb2Se3, Sb2Te3, SnS, SnSe, CdSe, CdTe, ZnSe, and ZnTe. Together with the calculated optical and mechanical properties, we demonstrate the efficacy of using this novel approach for materials design that could facilitate the exploration and development of new chalcogenide crystals and glasses. Moreover, the TBOD and its partial components (PBOD) could be the key descriptors in machine learning protocol for broader scale design when a large database is available.

Buried Narratives: Exhuming the Mother's Story in Oliver Twist

2018 ◽  
Vol 8 (3) ◽  
pp. 247-266
Author(s):  
Michelle L. Wilson
Keyword(s):  
Social Change ◽  
Maternal Inheritance ◽  
The Novel ◽  
Poor Law ◽  
The Family ◽  
The Law ◽  
First Time ◽  
Critical Consideration

Initially, Oliver Twist (1839) might seem representative of the archetypal male social plot, following an orphan and finding him a place by discovering the father and settling the boy within his inheritance. But Agnes Fleming haunts this narrative, undoing its neat, linear transmission. This reconsideration of maternal inheritance and plot in the novel occurs against the backdrop of legal and social change. I extend the critical consideration of the novel's relationship to the New Poor Law by thinking about its reflection on the bastardy clauses. And here, of course, is where the mother enters. Under the bastardy clauses, the responsibility for economic maintenance of bastard children was, for the first time, legally assigned to the mother, relieving the father of any and all obligation. Oliver Twist manages to critique the bastardy clauses for their release of the father, while simultaneously embracing the placement of the mother at the head of the family line. Both Oliver and the novel thus suggest that it is the mother's story that matters, her name through which we find our own. And by containing both plots – that of the father and the mother – Oliver Twist reveals the violence implicit in traditional modes of inheritance in the novel and under the law.

CONVEYOR MODEL AND IMPLEMENTATION OF THE REAL NUMBERS ADDER ON FPGA

2020 ◽  
Vol 33 (109) ◽  
pp. 21-31
Author(s):  
І. Ya. Zeleneva ◽  
Т. V. Golub ◽  
T. S. Diachuk ◽  
А. Ye. Didenko
Keyword(s):  
Performance Improvement ◽  
Experimental Studies ◽  
Production Costs ◽  
Floating Point ◽  
Computing Device ◽  
Quartus Ii ◽  
Functional Blocks ◽  
Mental Testing ◽  
Processor Cores ◽  
Floating Point Numbers

The purpose of these studies is to develop an effective structure and internal functional blocks of a digital computing device – an adder, that performs addition and subtraction operations on floating- point numbers presented in IEEE Std 754TM-2008 format. To improve the characteristics of the adder, the circuit uses conveying, that is, division into levels, each of which performs a specific action on numbers. This allows you to perform addition / subtraction operations on several numbers at the same time, which increas- es the performance of calculations, and also makes the adder suitable for use in modern synchronous cir- cuits. Each block of the conveyor structure of the adder on FPGA is synthesized as a separate project of a digital functional unit, and thus, the overall task is divided into separate subtasks, which facilitates experi- mental testing and phased debugging of the entire device. Experimental studies were performed using EDA Quartus II. The developed circuit was modeled on FPGAs of the Stratix III and Cyclone III family. An ana- logue of the developed circuit was a functionally similar device from Altera. A comparative analysis is made and reasoned conclusions are drawn that the performance improvement is achieved due to the conveyor structure of the adder. Implementation of arithmetic over the floating-point numbers on programmable logic integrated cir- cuits, in particular on FPGA, has such advantages as flexibility of use and low production costs, and also provides the opportunity to solve problems for which there are no ready-made solutions in the form of stand- ard devices presented on the market. The developed adder has a wide scope, since most modern computing devices need to process floating-point numbers. The proposed conveyor model of the adder is quite simple to implement on the FPGA and can be an alternative to using built-in multipliers and processor cores in cases where the complex functionality of these devices is redundant for a specific task.

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