Algorithmic Mechanism Design of Evolutionary Computation
Pei, Yan
2015-01-01
We consider algorithmic design, enhancement, and improvement of evolutionary computation as a mechanism design problem. All individuals or several groups of individuals can be considered as self-interested agents. The individuals in evolutionary computation can manipulate parameter settings and operations by satisfying their own preferences, which are defined by an evolutionary computation algorithm designer, rather than by following a fixed algorithm rule. Evolutionary computation algorithm designers or self-adaptive methods should construct proper rules and mechanisms for all agents (individuals) to conduct their evolution behaviour correctly in order to definitely achieve the desired and preset objective(s). As a case study, we propose a formal framework on parameter setting, strategy selection, and algorithmic design of evolutionary computation by considering the Nash strategy equilibrium of a mechanism design in the search process. The evaluation results present the efficiency of the framework. This primary principle can be implemented in any evolutionary computation algorithm that needs to consider strategy selection issues in its optimization process. The final objective of our work is to solve evolutionary computation design as an algorithmic mechanism design problem and establish its fundamental aspect by taking this perspective. This paper is the first step towards achieving this objective by implementing a strategy equilibrium solution (such as Nash equilibrium) in evolutionary computation algorithm. PMID:26257777
Algorithmic Mechanism Design of Evolutionary Computation.
Pei, Yan
2015-01-01
We consider algorithmic design, enhancement, and improvement of evolutionary computation as a mechanism design problem. All individuals or several groups of individuals can be considered as self-interested agents. The individuals in evolutionary computation can manipulate parameter settings and operations by satisfying their own preferences, which are defined by an evolutionary computation algorithm designer, rather than by following a fixed algorithm rule. Evolutionary computation algorithm designers or self-adaptive methods should construct proper rules and mechanisms for all agents (individuals) to conduct their evolution behaviour correctly in order to definitely achieve the desired and preset objective(s). As a case study, we propose a formal framework on parameter setting, strategy selection, and algorithmic design of evolutionary computation by considering the Nash strategy equilibrium of a mechanism design in the search process. The evaluation results present the efficiency of the framework. This primary principle can be implemented in any evolutionary computation algorithm that needs to consider strategy selection issues in its optimization process. The final objective of our work is to solve evolutionary computation design as an algorithmic mechanism design problem and establish its fundamental aspect by taking this perspective. This paper is the first step towards achieving this objective by implementing a strategy equilibrium solution (such as Nash equilibrium) in evolutionary computation algorithm. PMID:26257777
Genetic Algorithm for the Design of Electro-Mechanical Sigma Delta Modulator MEMS Sensors
Wilcock, Reuben; Kraft, Michael
2011-01-01
This paper describes a novel design methodology using non-linear models for complex closed loop electro-mechanical sigma-delta modulators (EMΣΔM) that is based on genetic algorithms and statistical variation analysis. The proposed methodology is capable of quickly and efficiently designing high performance, high order, closed loop, near-optimal systems that are robust to sensor fabrication tolerances and electronic component variation. The use of full non-linear system models allows significant higher order non-ideal effects to be taken into account, improving accuracy and confidence in the results. To demonstrate the effectiveness of the approach, two design examples are presented including a 5th order low-pass EMΣΔM for a MEMS accelerometer, and a 6th order band-pass EMΣΔM for the sense mode of a MEMS gyroscope. Each example was designed using the system in less than one day, with very little manual intervention. The strength of the approach is verified by SNR performances of 109.2 dB and 92.4 dB for the low-pass and band-pass system respectively, coupled with excellent immunities to fabrication tolerances and parameter mismatch. PMID:22163691
Shook, Richard; /Marquette U. /SLAC
2010-08-25
The particle beam of the SXR (soft x-ray) beam line in the LCLS (Linac Coherent Light Source) has a high intensity in order to penetrate through samples at the atomic level. However, the intensity is so high that many experiments fail because of severe damage. To correct this issue, attenuators are put into the beam line to reduce this intensity to a level suitable for experimentation. Attenuation is defined as 'the gradual loss in intensity of any flux through a medium' by [1]. It is found that Beryllium and Boron Carbide can survive the intensity of the beam. At very thin films, both of these materials work very well as filters for reducing the beam intensity. Using a total of 12 filters, the first 9 being made of Beryllium and the rest made of Boron Carbide, the beam's energy range of photons can be attenuated between 800 eV and 9000 eV. The design of the filters allows attenuation for different beam intensities so that experiments can obtain different intensities from the beam if desired. The step of attenuation varies, but is relative to the thickness of the filter as a power function of 2. A relationship for this is f(n) = x{sub 0}2{sup n} where n is the step of attenuation desired and x{sub 0} is the initial thickness of the material. To allow for this desired variation, a mechanism must be designed within the test chamber. This is visualized using a 3D computer aided design modeling tool known as Solid Edge.
NASA Technical Reports Server (NTRS)
1976-01-01
Design concepts for a 1000 mw thermal stationary power plant employing the UF6 fueled gas core breeder reactor are examined. Three design combinations-gaseous UF6 core with a solid matrix blanket, gaseous UF6 core with a liquid blanket, and gaseous UF6 core with a circulating blanket were considered. Results show the gaseous UF6 core with a circulating blanket was best suited to the power plant concept.
Design of robust systolic algorithms
Varman, P.J.; Fussell, D.S.
1983-01-01
A primary reason for the susceptibility of systolic algorithms to faults is their strong dependence on the interconnection between the processors in a systolic array. A technique to transform any linear systolic algorithm into an equivalent pipelined algorithm that executes on arbitrary trees is presented. 5 references.
Fashion sketch design by interactive genetic algorithms
NASA Astrophysics Data System (ADS)
Mok, P. Y.; Wang, X. X.; Xu, J.; Kwok, Y. L.
2012-11-01
Computer aided design is vitally important for the modern industry, particularly for the creative industry. Fashion industry faced intensive challenges to shorten the product development process. In this paper, a methodology is proposed for sketch design based on interactive genetic algorithms. The sketch design system consists of a sketch design model, a database and a multi-stage sketch design engine. First, a sketch design model is developed based on the knowledge of fashion design to describe fashion product characteristics by using parameters. Second, a database is built based on the proposed sketch design model to define general style elements. Third, a multi-stage sketch design engine is used to construct the design. Moreover, an interactive genetic algorithm (IGA) is used to accelerate the sketch design process. The experimental results have demonstrated that the proposed method is effective in helping laypersons achieve satisfied fashion design sketches.
NASA Astrophysics Data System (ADS)
Beets, Timothy A.; Beno, Joseph H.; Chun, Moo-Young; Lee, Sungho; Park, Chan; Rafal, Marc; Worthington, Michael S.; Yuk, In-Soo
2012-09-01
A near-infrared spectrograph (NIRS) has been designed and proposed for utilization as a first-light instrument on the Giant Magellan Telescope (GMT). GMTNIRS includes modular JHK, LM spectrograph units mounted to two sides of a cryogenic optical bench. The optical bench and surrounding, protective radiation (thermal) shield are containerized within a rigid cryostat vessel, which mounts to the GMT instrument platform. A support structure on the secondary side of the optical bench provides multi-dimensional stiffness to the optical bench, to prevent excessive displacements of the optical components during tracking of the telescope. Extensive mechanical simulation and optimization was utilized to arrive at synergistic designs of the optical bench, support structure, cryostat, and thermal isolation system. Additionally, detailed steady-state and transient thermal analyses were conducted to optimize and verify the mechanical designs to maximize thermal efficiency and to size cryogenic coolers and conductors. This paper explains the mechanical and thermal design points stemming from optical component placement and mounting and structural and thermal characteristics needed to achieve instrument science requirements. The thermal and mechanical simulations will be described and the data will be summarized. Sufficient details of the analyses and data will be provided to validate the design decisions.
NASA Technical Reports Server (NTRS)
Wolpert, David H.; Turner, Kagan
2004-01-01
The field of mechanism design is concerned with setting (incentives superimposed on) the utility functions of a group of players so as to induce desirable joint behavior of those players. It arose in the context of traditional equilibrium game theory applied to games involving human players. This has led it to have many implicit restrictions, which strongly limits its scope. In particular, it ignores many issues that are crucial for systems that are large (and therefore far off-equilibrium in general) and/or composed of non-human players (e.g., computer-based agents). This also means it has concentrated on issues that are often irrelevant in those broader domains (e.g., incentive compatibility). This paper illustrates these shortcomings by reviewing some of the recent theoretical work on the design of collectives, a body of work that constitutes a substantial broadening of mechanism design. It then presents computer experiments based on a recently suggested nanotechnology testbed that demonstrates the power of that extended version of mechanism design.
General lossless planar coupler design algorithms.
Vance, Rod
2015-08-01
This paper reviews and extends two classes of algorithms for the design of planar couplers with any unitary transfer matrix as design goals. Such couplers find use in optical sensing for fading free interferometry, coherent optical network demodulation, and also for quantum state preparation in quantum optical experiments and technology. The two classes are (1) "atomic coupler algorithms" decomposing a unitary transfer matrix into a planar network of 2×2 couplers, and (2) "Lie theoretic algorithms" concatenating unit cell devices with variable phase delay sets that form canonical coordinates for neighborhoods in the Lie group U(N), so that the concatenations realize any transfer matrix in U(N). As well as review, this paper gives (1) a Lie theoretic proof existence proof showing that both classes of algorithms work and (2) direct proofs of the efficacy of the "atomic coupler" algorithms. The Lie theoretic proof strengthens former results. 5×5 couplers designed by both methods are compared by Monte Carlo analysis, which would seem to imply atomic rather than Lie theoretic methods yield designs more resilient to manufacturing imperfections. PMID:26367295
Fast Fourier Transform algorithm design and tradeoffs
NASA Technical Reports Server (NTRS)
Kamin, Ray A., III; Adams, George B., III
1988-01-01
The Fast Fourier Transform (FFT) is a mainstay of certain numerical techniques for solving fluid dynamics problems. The Connection Machine CM-2 is the target for an investigation into the design of multidimensional Single Instruction Stream/Multiple Data (SIMD) parallel FFT algorithms for high performance. Critical algorithm design issues are discussed, necessary machine performance measurements are identified and made, and the performance of the developed FFT programs are measured. Fast Fourier Transform programs are compared to the currently best Cray-2 FFT program.
Automated Antenna Design with Evolutionary Algorithms
NASA Technical Reports Server (NTRS)
Linden, Derek; Hornby, Greg; Lohn, Jason; Globus, Al; Krishunkumor, K.
2006-01-01
Current methods of designing and optimizing antennas by hand are time and labor intensive, and limit complexity. Evolutionary design techniques can overcome these limitations by searching the design space and automatically finding effective solutions. In recent years, evolutionary algorithms have shown great promise in finding practical solutions in large, poorly understood design spaces. In particular, spacecraft antenna design has proven tractable to evolutionary design techniques. Researchers have been investigating evolutionary antenna design and optimization since the early 1990s, and the field has grown in recent years as computer speed has increased and electromagnetic simulators have improved. Two requirements-compliant antennas, one for ST5 and another for TDRS-C, have been automatically designed by evolutionary algorithms. The ST5 antenna is slated to fly this year, and a TDRS-C phased array element has been fabricated and tested. Such automated evolutionary design is enabled by medium-to-high quality simulators and fast modern computers to evaluate computer-generated designs. Evolutionary algorithms automate cut-and-try engineering, substituting automated search though millions of potential designs for intelligent search by engineers through a much smaller number of designs. For evolutionary design, the engineer chooses the evolutionary technique, parameters and the basic form of the antenna, e.g., single wire for ST5 and crossed-element Yagi for TDRS-C. Evolutionary algorithms then search for optimal configurations in the space defined by the engineer. NASA's Space Technology 5 (ST5) mission will launch three small spacecraft to test innovative concepts and technologies. Advanced evolutionary algorithms were used to automatically design antennas for ST5. The combination of wide beamwidth for a circularly-polarized wave and wide impedance bandwidth made for a challenging antenna design problem. From past experience in designing wire antennas, we chose to
Instrument design and optimization using genetic algorithms
Hoelzel, Robert; Bentley, Phillip M.; Fouquet, Peter
2006-10-15
This article describes the design of highly complex physical instruments by using a canonical genetic algorithm (GA). The procedure can be applied to all instrument designs where performance goals can be quantified. It is particularly suited to the optimization of instrument design where local optima in the performance figure of merit are prevalent. Here, a GA is used to evolve the design of the neutron spin-echo spectrometer WASP which is presently being constructed at the Institut Laue-Langevin, Grenoble, France. A comparison is made between this artificial intelligence approach and the traditional manual design methods. We demonstrate that the search of parameter space is more efficient when applying the genetic algorithm, and the GA produces a significantly better instrument design. Furthermore, it is found that the GA increases flexibility, by facilitating the reoptimization of the design after changes in boundary conditions during the design phase. The GA also allows the exploration of 'nonstandard' magnet coil geometries. We conclude that this technique constitutes a powerful complementary tool for the design and optimization of complex scientific apparatus, without replacing the careful thought processes employed in traditional design methods.
Fuzzy logic and guidance algorithm design
Leng, G.
1994-12-31
This paper explores the use of fuzzy logic for the design of a terminal guidance algorithm for an air to surface missile against a stationary target. The design objectives are (1) a smooth transition, at lock-on, (2) large impact angles and (3) self-limiting acceleration commands. The method of reverse kinematics is used in the design of the membership functions and the rule base. Simulation results for a Mach 0.8 missile with a 6g acceleration limit are compared with a traditional proportional navigation scheme.
Multidisciplinary design optimization using genetic algorithms
NASA Astrophysics Data System (ADS)
Unal, Resit
1994-12-01
Multidisciplinary design optimization (MDO) is an important step in the conceptual design and evaluation of launch vehicles since it can have a significant impact on performance and life cycle cost. The objective is to search the system design space to determine values of design variables that optimize the performance characteristic subject to system constraints. Gradient-based optimization routines have been used extensively for aerospace design optimization. However, one limitation of gradient based optimizers is their need for gradient information. Therefore, design problems which include discrete variables can not be studied. Such problems are common in launch vehicle design. For example, the number of engines and material choices must be integer values or assume only a few discrete values. In this study, genetic algorithms are investigated as an approach to MDO problems involving discrete variables and discontinuous domains. Optimization by genetic algorithms (GA) uses a search procedure which is fundamentally different from those gradient based methods. Genetic algorithms seek to find good solutions in an efficient and timely manner rather than finding the best solution. GA are designed to mimic evolutionary selection. A population of candidate designs is evaluated at each iteration, and each individual's probability of reproduction (existence in the next generation) depends on its fitness value (related to the value of the objective function). Progress toward the optimum is achieved by the crossover and mutation operations. GA is attractive since it uses only objective function values in the search process, so gradient calculations are avoided. Hence, GA are able to deal with discrete variables. Studies report success in the use of GA for aircraft design optimization studies, trajectory analysis, space structure design and control systems design. In these studies reliable convergence was achieved, but the number of function evaluations was large compared
Multidisciplinary design optimization using genetic algorithms
NASA Technical Reports Server (NTRS)
Unal, Resit
1994-01-01
Multidisciplinary design optimization (MDO) is an important step in the conceptual design and evaluation of launch vehicles since it can have a significant impact on performance and life cycle cost. The objective is to search the system design space to determine values of design variables that optimize the performance characteristic subject to system constraints. Gradient-based optimization routines have been used extensively for aerospace design optimization. However, one limitation of gradient based optimizers is their need for gradient information. Therefore, design problems which include discrete variables can not be studied. Such problems are common in launch vehicle design. For example, the number of engines and material choices must be integer values or assume only a few discrete values. In this study, genetic algorithms are investigated as an approach to MDO problems involving discrete variables and discontinuous domains. Optimization by genetic algorithms (GA) uses a search procedure which is fundamentally different from those gradient based methods. Genetic algorithms seek to find good solutions in an efficient and timely manner rather than finding the best solution. GA are designed to mimic evolutionary selection. A population of candidate designs is evaluated at each iteration, and each individual's probability of reproduction (existence in the next generation) depends on its fitness value (related to the value of the objective function). Progress toward the optimum is achieved by the crossover and mutation operations. GA is attractive since it uses only objective function values in the search process, so gradient calculations are avoided. Hence, GA are able to deal with discrete variables. Studies report success in the use of GA for aircraft design optimization studies, trajectory analysis, space structure design and control systems design. In these studies reliable convergence was achieved, but the number of function evaluations was large compared
Fuzzy controller design by parallel genetic algorithms
NASA Astrophysics Data System (ADS)
Mondelli, G.; Castellano, G.; Attolico, Giovanni; Distante, Arcangelo
1998-03-01
Designing a fuzzy system involves defining membership functions and constructing rules. Carrying out these two steps manually often results in a poorly performing system. Genetic Algorithms (GAs) has proved to be a useful tool for designing optimal fuzzy controller. In order to increase the efficiency and effectiveness of their application, parallel GAs (PAGs), evolving synchronously several populations with different balances between exploration and exploitation, have been implemented using a SIMD machine (APE100/Quadrics). The parameters to be identified are coded in such a way that the algorithm implicitly provides a compact fuzzy controller, by finding only necessary rules and removing useless inputs from them. Early results, working on a fuzzy controller implementing the wall-following task for a real vehicle as a test case, provided better fitness values in less generations with respect to previous experiments made using a sequential implementation of GAs.
Material design using surrogate optimization algorithm
NASA Astrophysics Data System (ADS)
Khadke, Kunal R.
Nanocomposite ceramics have been widely studied in order to tailor desired properties at high temperatures. Methodologies for development of material design are still under effect . While finite element modeling (FEM) provides significant insight on material behavior, few design researchers have addressed the design paradox that accompanies this rapid design space expansion. A surrogate optimization model management framework has been proposed to make this design process tractable. In the surrogate optimization material design tool, the analysis cost is reduced by performing simulations on the surrogate model instead of high density finite element model. The methodology is incorporated to find the optimal number of silicon carbide (SiC) particles, in a silicon-nitride Si3N 4 composite with maximum fracture energy [2]. Along with a deterministic optimization algorithm, model uncertainties have also been considered with the use of robust design optimization (RDO) method ensuring a design of minimum sensitivity to changes in the parameters. These methodologies applied to nanocomposites design have a signicant impact on cost and design cycle time reduced.
Designing conducting polymers using genetic algorithms
NASA Astrophysics Data System (ADS)
Giro, R.; Cyrillo, M.; Galvão, D. S.
2002-11-01
We have developed a new methodology to design conducting polymers with pre-specified properties. The methodology is based on the use of genetic algorithms (GAs) coupled to Negative Factor Counting technique. We present the results for a case study of polyanilines, one of the most important families of conducting polymers. The methodology proved to be able of generating automatic solutions for the problem of determining the optimum relative concentration for binary and ternary disordered polyaniline alloys exhibiting metallic properties. The methodology is completely general and can be used to design new classes of materials.
Predicting Resistance Mutations Using Protein Design Algorithms
Frey, K.; Georgiev, I; Donald, B; Anderson, A
2010-01-01
Drug resistance resulting from mutations to the target is an unfortunate common phenomenon that limits the lifetime of many of the most successful drugs. In contrast to the investigation of mutations after clinical exposure, it would be powerful to be able to incorporate strategies early in the development process to predict and overcome the effects of possible resistance mutations. Here we present a unique prospective application of an ensemble-based protein design algorithm, K*, to predict potential resistance mutations in dihydrofolate reductase from Staphylococcus aureus using positive design to maintain catalytic function and negative design to interfere with binding of a lead inhibitor. Enzyme inhibition assays show that three of the four highly-ranked predicted mutants are active yet display lower affinity (18-, 9-, and 13-fold) for the inhibitor. A crystal structure of the top-ranked mutant enzyme validates the predicted conformations of the mutated residues and the structural basis of the loss of potency. The use of protein design algorithms to predict resistance mutations could be incorporated in a lead design strategy against any target that is susceptible to mutational resistance.
Fast search algorithms for computational protein design.
Traoré, Seydou; Roberts, Kyle E; Allouche, David; Donald, Bruce R; André, Isabelle; Schiex, Thomas; Barbe, Sophie
2016-05-01
One of the main challenges in computational protein design (CPD) is the huge size of the protein sequence and conformational space that has to be computationally explored. Recently, we showed that state-of-the-art combinatorial optimization technologies based on Cost Function Network (CFN) processing allow speeding up provable rigid backbone protein design methods by several orders of magnitudes. Building up on this, we improved and injected CFN technology into the well-established CPD package Osprey to allow all Osprey CPD algorithms to benefit from associated speedups. Because Osprey fundamentally relies on the ability of A* to produce conformations in increasing order of energy, we defined new A* strategies combining CFN lower bounds, with new side-chain positioning-based branching scheme. Beyond the speedups obtained in the new A*-CFN combination, this novel branching scheme enables a much faster enumeration of suboptimal sequences, far beyond what is reachable without it. Together with the immediate and important speedups provided by CFN technology, these developments directly benefit to all the algorithms that previously relied on the DEE/ A* combination inside Osprey* and make it possible to solve larger CPD problems with provable algorithms. PMID:26833706
Problem Solving Techniques for the Design of Algorithms.
ERIC Educational Resources Information Center
Kant, Elaine; Newell, Allen
1984-01-01
Presents model of algorithm design (activity in software development) based on analysis of protocols of two subjects designing three convex hull algorithms. Automation methods, methods for studying algorithm design, role of discovery in problem solving, and comparison of different designs of case study according to model are highlighted.…
NASA Technical Reports Server (NTRS)
Roth, J. P.
1972-01-01
Methods for development of logic design together with algorithms for failure testing, a method for design of logic for ultra-large-scale integration, extension of quantum calculus to describe the functional behavior of a mechanism component-by-component and to computer tests for failures in the mechanism using the diagnosis algorithm, and the development of an algorithm for the multi-output 2-level minimization problem are discussed.
Algorithm design of liquid lens inspection system
NASA Astrophysics Data System (ADS)
Hsieh, Lu-Lin; Wang, Chun-Chieh
2008-08-01
In mobile lens domain, the glass lens is often to be applied in high-resolution requirement situation; but the glass zoom lens needs to be collocated with movable machinery and voice-coil motor, which usually arises some space limits in minimum design. In high level molding component technology development, the appearance of liquid lens has become the focus of mobile phone and digital camera companies. The liquid lens sets with solid optical lens and driving circuit has replaced the original components. As a result, the volume requirement is decreased to merely 50% of the original design. Besides, with the high focus adjusting speed, low energy requirement, high durability, and low-cost manufacturing process, the liquid lens shows advantages in the competitive market. In the past, authors only need to inspect the scrape defect made by external force for the glass lens. As to the liquid lens, authors need to inspect the state of four different structural layers due to the different design and structure. In this paper, authors apply machine vision and digital image processing technology to administer inspections in the particular layer according to the needs of users. According to our experiment results, the algorithm proposed can automatically delete non-focus background, extract the region of interest, find out and analyze the defects efficiently in the particular layer. In the future, authors will combine the algorithm of the system with automatic-focus technology to implement the inside inspection based on the product inspective demands.
Optimal Design of Geodetic Network Using Genetic Algorithms
NASA Astrophysics Data System (ADS)
Vajedian, Sanaz; Bagheri, Hosein
2010-05-01
A geodetic network is a network which is measured exactly by techniques of terrestrial surveying based on measurement of angles and distances and can control stability of dams, towers and their around lands and can monitor deformation of surfaces. The main goals of an optimal geodetic network design process include finding proper location of control station (First order Design) as well as proper weight of observations (second order observation) in a way that satisfy all the criteria considered for quality of the network with itself is evaluated by the network's accuracy, reliability (internal and external), sensitivity and cost. The first-order design problem, can be dealt with as a numeric optimization problem. In this designing finding unknown coordinates of network stations is an important issue. For finding these unknown values, network geodetic observations that are angle and distance measurements must be entered in an adjustment method. In this regard, using inverse problem algorithms is needed. Inverse problem algorithms are methods to find optimal solutions for given problems and include classical and evolutionary computations. The classical approaches are analytical methods and are useful in finding the optimum solution of a continuous and differentiable function. Least squares (LS) method is one of the classical techniques that derive estimates for stochastic variables and their distribution parameters from observed samples. The evolutionary algorithms are adaptive procedures of optimization and search that find solutions to problems inspired by the mechanisms of natural evolution. These methods generate new points in the search space by applying operators to current points and statistically moving toward more optimal places in the search space. Genetic algorithm (GA) is an evolutionary algorithm considered in this paper. This algorithm starts with definition of initial population, and then the operators of selection, replication and variation are applied
Design of SPARC V8 superscalar pipeline applied Tomasulo's algorithm
NASA Astrophysics Data System (ADS)
Yang, Xue; Yu, Lixin; Feng, Yunkai
2014-04-01
A superscalar pipeline applied Tomasulo's algorithm is presented in this paper. The design begins with a dual-issue superscalar processor based on LEON2. Tomasulo's algorithm is adopted to implement out-of-order execution. Instructions are separated into three different parts and executed by three different function units so as to reduce area and promote execution speed. Results wrote back into registers are still in program order, for the aim of ensure the function veracity. Mechanisms of the reservation station, common data bus, and reorder buffer are presented in detail. The structure can sends and executes three instructions at most at a time. Branch prediction can also be realized by reorder buffer. Performance of the scalar pipeline applied Tomasulo's algorithm is promoted by 41.31% compared to singleissue pipeline..
Design of Protein-Protein Interactions with a Novel Ensemble-Based Scoring Algorithm
NASA Astrophysics Data System (ADS)
Roberts, Kyle E.; Cushing, Patrick R.; Boisguerin, Prisca; Madden, Dean R.; Donald, Bruce R.
Protein-protein interactions (PPIs) are vital for cell signaling, protein trafficking and localization, gene expression, and many other biological functions. Rational modification of PPI targets provides a mechanism to understand their function and importance. However, PPI systems often have many more degrees of freedom and flexibility than the small-molecule binding sites typically targeted by protein design algorithms. To handle these challenging design systems, we have built upon the computational protein design algorithm K * [8,19] to develop a new design algorithm to study protein-protein and protein-peptide interactions. We validated our algorithm through the design and experimental testing of novel peptide inhibitors.
UWB Tracking System Design with TDOA Algorithm
NASA Technical Reports Server (NTRS)
Ni, Jianjun; Arndt, Dickey; Ngo, Phong; Phan, Chau; Gross, Julia; Dusl, John; Schwing, Alan
2006-01-01
This presentation discusses an ultra-wideband (UWB) tracking system design effort using a tracking algorithm TDOA (Time Difference of Arrival). UWB technology is exploited to implement the tracking system due to its properties, such as high data rate, fine time resolution, and low power spectral density. A system design using commercially available UWB products is proposed. A two-stage weighted least square method is chosen to solve the TDOA non-linear equations. Matlab simulations in both two-dimensional space and three-dimensional space show that the tracking algorithm can achieve fine tracking resolution with low noise TDOA data. The error analysis reveals various ways to improve the tracking resolution. Lab experiments demonstrate the UWBTDOA tracking capability with fine resolution. This research effort is motivated by a prototype development project Mini-AERCam (Autonomous Extra-vehicular Robotic Camera), a free-flying video camera system under development at NASA Johnson Space Center for aid in surveillance around the International Space Station (ISS).
Optimal brushless DC motor design using genetic algorithms
NASA Astrophysics Data System (ADS)
Rahideh, A.; Korakianitis, T.; Ruiz, P.; Keeble, T.; Rothman, M. T.
2010-11-01
This paper presents a method for the optimal design of a slotless permanent magnet brushless DC (BLDC) motor with surface mounted magnets using a genetic algorithm. Characteristics of the motor are expressed as functions of motor geometries. The objective function is a combination of losses, volume and cost to be minimized simultaneously. Electrical and mechanical requirements (i.e. voltage, torque and speed) and other limitations (e.g. upper and lower limits of the motor geometries) are cast into constraints of the optimization problem. One sample case is used to illustrate the design and optimization technique.
Algorithmic Processes for Increasing Design Efficiency.
ERIC Educational Resources Information Center
Terrell, William R.
1983-01-01
Discusses the role of algorithmic processes as a supplementary method for producing cost-effective and efficient instructional materials. Examines three approaches to problem solving in the context of developing training materials for the Naval Training Command: application of algorithms, quasi-algorithms, and heuristics. (EAO)
In-Trail Procedure (ITP) Algorithm Design
NASA Technical Reports Server (NTRS)
Munoz, Cesar A.; Siminiceanu, Radu I.
2007-01-01
The primary objective of this document is to provide a detailed description of the In-Trail Procedure (ITP) algorithm, which is part of the Airborne Traffic Situational Awareness In-Trail Procedure (ATSA-ITP) application. To this end, the document presents a high level description of the ITP Algorithm and a prototype implementation of this algorithm in the programming language C.
Optimization Algorithm for Designing Diffractive Optical Elements
NASA Astrophysics Data System (ADS)
Agudelo, Viviana A.; Orozco, Ricardo Amézquita
2008-04-01
Diffractive Optical Elements (DOEs) are commonly used in many applications such as laser beam shaping, recording of micro reliefs, wave front analysis, metrology and many others where they can replace single or multiple conventional optical elements (diffractive or refractive). One of the most versatile way to produce them, is to use computer assisted techniques for their design and optimization, as well as optical or electron beam micro-lithography techniques for the final fabrication. The fundamental figures of merit involved in the optimization of such devices are both the diffraction efficiency and the signal to noise ratio evaluated in the reconstructed wave front at the image plane. A design and optimization algorithm based on the error—reduction method (Gerchberg and Saxton) is proposed to obtain binary discrete phase-only Fresnel DOEs that will be used to produce specific intensity patterns. Some experimental results were obtained using a spatial light modulator acting as a binary programmable diffractive phase element. Although the DOEs optimized here are discrete in phase, they present an acceptable signal noise relation and diffraction efficiency.
Birefringent filter design by use of a modified genetic algorithm.
Wen, Mengtao; Yao, Jianping
2006-06-10
A modified genetic algorithm is proposed for the optimization of fiber birefringent filters. The orientation angles and the element lengths are determined by the genetic algorithm to minimize the sidelobe levels of the filters. Being different from the normal genetic algorithm, the algorithm proposed reduces the problem space of the birefringent filter design to achieve faster speed and better performance. The design of 4-, 8-, and 14-section birefringent filters with an improved sidelobe suppression ratio is realized. A 4-section birefringent filter designed with the algorithm is experimentally realized. PMID:16761031
Organization mechanism and counting algorithm on vertex-cover solutions
NASA Astrophysics Data System (ADS)
Wei, Wei; Zhang, Renquan; Niu, Baolong; Guo, Binghui; Zheng, Zhiming
2015-04-01
Counting the solution number of combinational optimization problems is an important topic in the study of computational complexity, which is concerned with Vertex-Cover in this paper. First, we investigate organizations of Vertex-Cover solution spaces by the underlying connectivity of unfrozen vertices and provide facts on the global and local environment. Then, a Vertex-Cover Solution Number Counting Algorithm is proposed and its complexity analysis is provided, the results of which fit very well with the simulations and have a better performance than those by 1-RSB in the neighborhood of c = e for random graphs. Based on the algorithm, variation and fluctuation on the solution number the statistics are studied to reveal the evolution mechanism of the solution numbers. Furthermore, the marginal probability distributions on the solution space are investigated on both the random graph and scale-free graph to illustrate the different evolution characteristics of their solution spaces. Thus, doing solution number counting based on the graph expression of the solution space should be an alternative and meaningful way to study the hardness of NP-complete and #P-complete problems and the appropriate algorithm design can help to achieve better approximations of solving combinational optimization problems and the corresponding counting problems.
An assessment of 'shuffle algorithm' collision mechanics for particle simulations
NASA Technical Reports Server (NTRS)
Feiereisen, William J.; Boyd, Iain D.
1991-01-01
Among the algorithms for collision mechanics used at present, the 'shuffle algorithm' of Baganoff (McDonald and Baganoff, 1988; Baganoff and McDonald, 1990) not only allows efficient vectorization, but also discretizes the possible outcomes of a collision. To assess the applicability of the shuffle algorithm, a simulation was performed of flows in monoatomic gases and the calculated characteristics of shock waves was compared with those obtained using a commonly employed isotropic scattering law. It is shown that, in general, the shuffle algorithm adequately represents the collision mechanics in cases when the goal of calculations are mean profiles of density and temperature.
Testing block subdivision algorithms on block designs
NASA Astrophysics Data System (ADS)
Wiseman, Natalie; Patterson, Zachary
2016-01-01
Integrated land use-transportation models predict future transportation demand taking into account how households and firms arrange themselves partly as a function of the transportation system. Recent integrated models require parcels as inputs and produce household and employment predictions at the parcel scale. Block subdivision algorithms automatically generate parcel patterns within blocks. Evaluating block subdivision algorithms is done by way of generating parcels and comparing them to those in a parcel database. Three block subdivision algorithms are evaluated on how closely they reproduce parcels of different block types found in a parcel database from Montreal, Canada. While the authors who developed each of the algorithms have evaluated them, they have used their own metrics and block types to evaluate their own algorithms. This makes it difficult to compare their strengths and weaknesses. The contribution of this paper is in resolving this difficulty with the aim of finding a better algorithm suited to subdividing each block type. The proposed hypothesis is that given the different approaches that block subdivision algorithms take, it's likely that different algorithms are better adapted to subdividing different block types. To test this, a standardized block type classification is used that consists of mutually exclusive and comprehensive categories. A statistical method is used for finding a better algorithm and the probability it will perform well for a given block type. Results suggest the oriented bounding box algorithm performs better for warped non-uniform sites, as well as gridiron and fragmented uniform sites. It also produces more similar parcel areas and widths. The Generalized Parcel Divider 1 algorithm performs better for gridiron non-uniform sites. The Straight Skeleton algorithm performs better for loop and lollipop networks as well as fragmented non-uniform and warped uniform sites. It also produces more similar parcel shapes and patterns.
Mechanical Design Handbook for Elastomers
NASA Technical Reports Server (NTRS)
Darlow, M.; Zorzi, E.
1986-01-01
Mechanical Design Handbook for Elastomers reviews state of art in elastomer-damper technology with particular emphasis on applications of highspeed rotor dampers. Self-contained reference but includes some theoretical discussion to help reader understand how and why dampers used for rotating machines. Handbook presents step-by-step procedure for design of elastomer dampers and detailed examples of actual elastomer damper applications.
HEURISTIC OPTIMIZATION AND ALGORITHM TUNING APPLIED TO SORPTIVE BARRIER DESIGN
While heuristic optimization is applied in environmental applications, ad-hoc algorithm configuration is typical. We use a multi-layer sorptive barrier design problem as a benchmark for an algorithm-tuning procedure, as applied to three heuristics (genetic algorithms, simulated ...
Parallel optimization algorithms and their implementation in VLSI design
NASA Technical Reports Server (NTRS)
Lee, G.; Feeley, J. J.
1991-01-01
Two new parallel optimization algorithms based on the simplex method are described. They may be executed by a SIMD parallel processor architecture and be implemented in VLSI design. Several VLSI design implementations are introduced. An application example is reported to demonstrate that the algorithms are effective.
NASA Technical Reports Server (NTRS)
Roth, J. P.
1972-01-01
The following problems are considered: (1) methods for development of logic design together with algorithms, so that it is possible to compute a test for any failure in the logic design, if such a test exists, and developing algorithms and heuristics for the purpose of minimizing the computation for tests; and (2) a method of design of logic for ultra LSI (large scale integration). It was discovered that the so-called quantum calculus can be extended to render it possible: (1) to describe the functional behavior of a mechanism component by component, and (2) to compute tests for failures, in the mechanism, using the diagnosis algorithm. The development of an algorithm for the multioutput two-level minimization problem is presented and the program MIN 360 was written for this algorithm. The program has options of mode (exact minimum or various approximations), cost function, cost bound, etc., providing flexibility.
Optimal Pid Controller Design Using Adaptive Vurpso Algorithm
NASA Astrophysics Data System (ADS)
Zirkohi, Majid Moradi
2015-04-01
The purpose of this paper is to improve theVelocity Update Relaxation Particle Swarm Optimization algorithm (VURPSO). The improved algorithm is called Adaptive VURPSO (AVURPSO) algorithm. Then, an optimal design of a Proportional-Integral-Derivative (PID) controller is obtained using the AVURPSO algorithm. An adaptive momentum factor is used to regulate a trade-off between the global and the local exploration abilities in the proposed algorithm. This operation helps the system to reach the optimal solution quickly and saves the computation time. Comparisons on the optimal PID controller design confirm the superiority of AVURPSO algorithm to the optimization algorithms mentioned in this paper namely the VURPSO algorithm, the Ant Colony algorithm, and the conventional approach. Comparisons on the speed of convergence confirm that the proposed algorithm has a faster convergence in a less computation time to yield a global optimum value. The proposed AVURPSO can be used in the diverse areas of optimization problems such as industrial planning, resource allocation, scheduling, decision making, pattern recognition and machine learning. The proposed AVURPSO algorithm is efficiently used to design an optimal PID controller.
Aerodynamic optimum design of transonic turbine cascades using Genetic Algorithms
NASA Astrophysics Data System (ADS)
Li, Jun; Feng, Zhenping; Chang, Jianzhong; Shen, Zuda
1997-06-01
This paper presents an aerodynamic optimum design method for transonic turbine cascades based on the Genetic Algorithms coupled to the inviscid flow Euler solver and the boundary-layer calculation. The Genetic Algorithms control the evolution of a population of cascades towards an optimum design. The fitness value of each string is evaluated using the flow solver. The design procedure has been developed and the behavior of the genetic algorithms has been tested. The objective functions of the design examples are the minimum mean-square deviation between the aimed pressure and computed pressure and the minimum amount of user expertise.
Extrapolated gradientlike algorithms for molecular dynamics and celestial mechanics simulations.
Omelyan, I P
2006-09-01
A class of symplectic algorithms is introduced to integrate the equations of motion in many-body systems. The algorithms are derived on the basis of an advanced gradientlike decomposition approach. Its main advantage over the standard gradient scheme is the avoidance of time-consuming evaluations of force gradients by force extrapolation without any loss of precision. As a result, the efficiency of the integration improves significantly. The algorithms obtained are analyzed and optimized using an error-function theory. The best among them are tested in actual molecular dynamics and celestial mechanics simulations for comparison with well-known nongradient and gradient algorithms such as the Störmer-Verlet, Runge-Kutta, Cowell-Numerov, Forest-Ruth, Suzuki-Chin, and others. It is demonstrated that for moderate and high accuracy, the extrapolated algorithms should be considered as the most efficient for the integration of motion in molecular dynamics simulations. PMID:17025782
A parallel sparse algorithm targeting arterial fluid mechanics computations
NASA Astrophysics Data System (ADS)
Manguoglu, Murat; Takizawa, Kenji; Sameh, Ahmed H.; Tezduyar, Tayfun E.
2011-09-01
Iterative solution of large sparse nonsymmetric linear equation systems is one of the numerical challenges in arterial fluid-structure interaction computations. This is because the fluid mechanics parts of the fluid + structure block of the equation system that needs to be solved at every nonlinear iteration of each time step corresponds to incompressible flow, the computational domains include slender parts, and accurate wall shear stress calculations require boundary layer mesh refinement near the arterial walls. We propose a hybrid parallel sparse algorithm, domain-decomposing parallel solver (DDPS), to address this challenge. As the test case, we use a fluid mechanics equation system generated by starting with an arterial shape and flow field coming from an FSI computation and performing two time steps of fluid mechanics computation with a prescribed arterial shape change, also coming from the FSI computation. We show how the DDPS algorithm performs in solving the equation system and demonstrate the scalability of the algorithm.
A generalized algorithm to design finite field normal basis multipliers
NASA Technical Reports Server (NTRS)
Wang, C. C.
1986-01-01
Finite field arithmetic logic is central in the implementation of some error-correcting coders and some cryptographic devices. There is a need for good multiplication algorithms which can be easily realized. Massey and Omura recently developed a new multiplication algorithm for finite fields based on a normal basis representation. Using the normal basis representation, the design of the finite field multiplier is simple and regular. The fundamental design of the Massey-Omura multiplier is based on a design of a product function. In this article, a generalized algorithm to locate a normal basis in a field is first presented. Using this normal basis, an algorithm to construct the product function is then developed. This design does not depend on particular characteristics of the generator polynomial of the field.
A Parallel Genetic Algorithm for Automated Electronic Circuit Design
NASA Technical Reports Server (NTRS)
Lohn, Jason D.; Colombano, Silvano P.; Haith, Gary L.; Stassinopoulos, Dimitris; Norvig, Peter (Technical Monitor)
2000-01-01
We describe a parallel genetic algorithm (GA) that automatically generates circuit designs using evolutionary search. A circuit-construction programming language is introduced and we show how evolution can generate practical analog circuit designs. Our system allows circuit size (number of devices), circuit topology, and device values to be evolved. We present experimental results as applied to analog filter and amplifier design tasks.
On the design, analysis, and implementation of efficient parallel algorithms
Sohn, S.M.
1989-01-01
There is considerable interest in developing algorithms for a variety of parallel computer architectures. This is not a trivial problem, although for certain models great progress has been made. Recently, general-purpose parallel machines have become available commercially. These machines possess widely varying interconnection topologies and data/instruction access schemes. It is important, therefore, to develop methodologies and design paradigms for not only synthesizing parallel algorithms from initial problem specifications, but also for mapping algorithms between different architectures. This work has considered both of these problems. A systolic array consists of a large collection of simple processors that are interconnected in a uniform pattern. The author has studied in detain the problem of mapping systolic algorithms onto more general-purpose parallel architectures such as the hypercube. The hypercube architecture is notable due to its symmetry and high connectivity, characteristics which are conducive to the efficient embedding of parallel algorithms. Although the parallel-to-parallel mapping techniques have yielded efficient target algorithms, it is not surprising that an algorithm designed directly for a particular parallel model would achieve superior performance. In this context, the author has developed hypercube algorithms for some important problems in speech and signal processing, text processing, language processing and artificial intelligence. These algorithms were implemented on a 64-node NCUBE/7 hypercube machine in order to evaluate their performance.
Mechanical flexible joint design document
NASA Technical Reports Server (NTRS)
Daily, Vic
1993-01-01
The purpose of this report is to document the status of the Mechanical Flexible Joint (MFJ) Design Subtask with the intent of halting work on the design. Recommendations for future work is included in the case that the task is to be resumed. The MFJ is designed to eliminate two failure points from the current flex joint configuration, the inner 'tripod configuration' and the outer containment jacket. The MFJ will also be designed to flex 13.5 degrees and have three degrees of freedom. By having three degrees of freedom, the MFJ will allow the Low Pressure Fuel Duct to twist and remove the necessity to angulate the full 11 degrees currently required. The current flex joints are very labor intensive and very costly and a simple alternative is being sought. The MFJ is designed with a greater angular displacement, with three degrees of freedom, to reside in the same overall envelope, to meet weight constraints of the current bellows, to be compatible with cryogenic fuel and oxidizers, and also to be man-rated.
Genetic algorithms for the construction of D-optimal designs
Heredia-Langner, Alejandro; Carlyle, W M.; Montgomery, D C.; Borror, Connie M.; Runger, George C.
2003-01-01
Computer-generated designs are useful for situations where standard factorial, fractional factorial or response surface designs cannot be easily employed. Alphabetically-optimal designs are the most widely used type of computer-generated designs, and of these, the D-optimal (or D-efficient) class of designs are extremely popular. D-optimal designs are usually constructed by algorithms that sequentially add and delete points from a potential design based using a candidate set of points spaced over the region of interest. We present a technique to generate D-efficient designs using genetic algorithms (GA). This approach eliminates the need to explicitly consider a candidate set of experimental points and it can handle highly constrained regions while maintaining a level of performance comparable to more traditional design construction techniques.
Evaluation of Mechanical Losses in Piezoelectric Plates using Genetic algorithm
NASA Astrophysics Data System (ADS)
Arnold, F. J.; Gonçalves, M. S.; Massaro, F. R.; Martins, P. S.
Numerical methods are used for the characterization of piezoelectric ceramics. A procedure based on genetic algorithm is applied to find the physical coefficients and mechanical losses. The coefficients are estimated from a minimum scoring of cost function. Electric impedances are calculated from Mason's model including mechanical losses constant and dependent on frequency as a linear function. The results show that the electric impedance percentage error in the investigated interval of frequencies decreases when mechanical losses depending on frequency are inserted in the model. A more accurate characterization of the piezoelectric ceramics mechanical losses should be considered as frequency dependent.
Algorithme intelligent d'optimisation d'un design structurel de grande envergure
NASA Astrophysics Data System (ADS)
Dominique, Stephane
The implementation of an automated decision support system in the field of design and structural optimisation can give a significant advantage to any industry working on mechanical designs. Indeed, by providing solution ideas to a designer or by upgrading existing design solutions while the designer is not at work, the system may reduce the project cycle time, or allow more time to produce a better design. This thesis presents a new approach to automate a design process based on Case-Based Reasoning (CBR), in combination with a new genetic algorithm named Genetic Algorithm with Territorial core Evolution (GATE). This approach was developed in order to reduce the operating cost of the process. However, as the system implementation cost is quite expensive, the approach is better suited for large scale design problem, and particularly for design problems that the designer plans to solve for many different specification sets. First, the CBR process uses a databank filled with every known solution to similar design problems. Then, the closest solutions to the current problem in term of specifications are selected. After this, during the adaptation phase, an artificial neural network (ANN) interpolates amongst known solutions to produce an additional solution to the current problem using the current specifications as inputs. Each solution produced and selected by the CBR is then used to initialize the population of an island of the genetic algorithm. The algorithm will optimise the solution further during the refinement phase. Using progressive refinement, the algorithm starts using only the most important variables for the problem. Then, as the optimisation progress, the remaining variables are gradually introduced, layer by layer. The genetic algorithm that is used is a new algorithm specifically created during this thesis to solve optimisation problems from the field of mechanical device structural design. The algorithm is named GATE, and is essentially a real number
The study on gear transmission multi-objective optimum design based on SQP algorithm
NASA Astrophysics Data System (ADS)
Li, Quancai; Qiao, Xuetao; Wu, Cuirong; Wang, Xingxing
2011-12-01
Gear mechanism is the most popular transmission mechanism; however, the traditional design method is complex and not accurate. Optimization design is the effective method to solve the above problems, used in gear design method. In many of the optimization software MATLAB, there are obvious advantage projects and numerical calculation. There is a single gear transmission as example, the mathematical model of gear transmission system, based on the analysis of the objective function, and on the basis of design variables and confirmation of choice restrictive conditions. The results show that the algorithm through MATLAB, the optimization designs, efficient, reliable, simple.
NASA Astrophysics Data System (ADS)
Grill, M.; Radovan, M.; Melchiorri, R.; Slanger, T. G.
2009-12-01
The Compact Echelle Spectrograph for Aeronomical Research (CESAR) covers the wavelength range from 300 to 1000 nm with a spectral resolution of 20,000. It is being constructed at SRI International with funds from the National Science Foundation's Major Research Instrumentation Program. Our goal is to significantly expand the range of upper atmospheric science investigations (nightglow, aurora, and dayglow emissions) by providing to aeronomers a high-throughput, high-dispersion, large-passband spectrograph by scaling an astronomical grade echelle spectrograph into a portable version capable of siting at multiple geophysically significant stations, heretofore only available to astronomers at a handful of large observatories. We present major aspects of the ongoing opto-mechanical design. The design incorporates lessons learned from the construction of the High Resolution Echelle Spectrometer (HiRES) and the Automated Planet Finder (APF) spectrometer, amongst others. All major optical components are mounted on kinematically fully determined hexapod structures, giving unprecedented three-dimensional adjustment capability. CESAR is designed to operate in an outdoors environment in remote locations such as the Poker Flat Research Range (PFRR) in Alaska. We present an enclosure concept that will allow CESAR to withstand the weather conditions found at such sites while still giving CESAR's fore-optics full access to the sky.
Acoustic design of rotor blades using a genetic algorithm
NASA Technical Reports Server (NTRS)
Wells, V. L.; Han, A. Y.; Crossley, W. A.
1995-01-01
A genetic algorithm coupled with a simplified acoustic analysis was used to generate low-noise rotor blade designs. The model includes thickness, steady loading and blade-vortex interaction noise estimates. The paper presents solutions for several variations in the fitness function, including thickness noise only, loading noise only, and combinations of the noise types. Preliminary results indicate that the analysis provides reasonable assessments of the noise produced, and that genetic algorithm successfully searches for 'good' designs. The results show that, for a given required thrust coefficient, proper blade design can noticeably reduce the noise produced at some expense to the power requirements.
Optimal fractional order PID design via Tabu Search based algorithm.
Ateş, Abdullah; Yeroglu, Celaleddin
2016-01-01
This paper presents an optimization method based on the Tabu Search Algorithm (TSA) to design a Fractional-Order Proportional-Integral-Derivative (FOPID) controller. All parameter computations of the FOPID employ random initial conditions, using the proposed optimization method. Illustrative examples demonstrate the performance of the proposed FOPID controller design method. PMID:26652128
Generation of Compliant Mechanisms using Hybrid Genetic Algorithm
NASA Astrophysics Data System (ADS)
Sharma, D.; Deb, K.
2014-10-01
Compliant mechanism is a single piece elastic structure which can deform to perform the assigned task. In this work, compliant mechanisms are evolved using a constraint based bi-objective optimization formulation which requires one user defined parameter ( η). This user defined parameter limits a gap between a desired path and an actual path traced by the compliant mechanism. The non-linear and discrete optimization problems are solved using the hybrid Genetic Algorithm (GA) wherein domain specific initialization, two-dimensional crossover operator and repairing techniques are adopted. A bit-wise local search method is used with elitist non-dominated sorting genetic algorithm to further refine the compliant mechanisms. Parallel computations are performed on the master-slave architecture to reduce the computation time. A parametric study is carried out for η value which suggests a range to evolve topologically different compliant mechanisms. The applied and boundary conditions to the compliant mechanisms are considered the variables that are evolved by the hybrid GA. The post-analysis of results unveils that the complaint mechanisms are always supported at unique location that can evolve the non-dominated solutions.
Superspreading: mechanisms and molecular design.
Theodorakis, Panagiotis E; Müller, Erich A; Craster, Richard V; Matar, Omar K
2015-03-01
The intriguing ability of certain surfactant molecules to drive the superspreading of liquids to complete wetting on hydrophobic substrates is central to numerous applications that range from coating flow technology to enhanced oil recovery. Despite significant experimental efforts, the precise mechanisms underlying superspreading remain unknown to date. Here, we isolate these mechanisms by analyzing coarse-grained molecular dynamics simulations of surfactant molecules of varying molecular architecture and substrate affinity. We observe that for superspreading to occur, two key conditions must be simultaneously satisfied: the adsorption of surfactants from the liquid-vapor surface onto the three-phase contact line augmented by local bilayer formation. Crucially, this must be coordinated with the rapid replenishment of liquid-vapor and solid-liquid interfaces with surfactants from the interior of the droplet. This article also highlights and explores the differences between superspreading and conventional surfactants, paving the way for the design of molecular architectures tailored specifically for applications that rely on the control of wetting. PMID:25658859
Microgel mechanics in biomaterial design.
Saxena, Shalini; Hansen, Caroline E; Lyon, L Andrew
2014-08-19
The field of polymeric biomaterials has received much attention in recent years due to its potential for enhancing the biocompatibility of systems and devices applied to drug delivery and tissue engineering. Such applications continually push the definition of biocompatibility from relatively straightforward issues such as cytotoxicity to significantly more complex processes such as reducing foreign body responses or even promoting/recapitulating natural body functions. Hydrogels and their colloidal analogues, microgels, have been and continue to be heavily investigated as viable materials for biological applications because they offer numerous, facile avenues in tailoring chemical and physical properties to approach biologically harmonious integration. Mechanical properties in particular are recently coming into focus as an important manner in which biological responses can be altered. In this Account, we trace how mechanical properties of microgels have moved into the spotlight of research efforts with the realization of their potential impact in biologically integrative systems. We discuss early experiments in our lab and in others focused on synthetic modulation of particle structure at a rudimentary level for fundamental drug delivery studies. These experiments elucidated that microgel mechanics are a consequence of polymer network distribution, which can be controlled by chemical composition or particle architecture. The degree of deformability designed into the microgel allows for a defined response to an imposed external force. We have studied deformation in packed colloidal phases and in translocation events through confined pores; in all circumstances, microgels exhibit impressive deformability in response to their environmental constraints. Microgels further translate their mechanical properties when assembled in films to the properties of the bulk material. In particular, microgel films have been a large focus in our lab as building blocks for self
An optimal structural design algorithm using optimality criteria
NASA Technical Reports Server (NTRS)
Taylor, J. E.; Rossow, M. P.
1976-01-01
An algorithm for optimal design is given which incorporates several of the desirable features of both mathematical programming and optimality criteria, while avoiding some of the undesirable features. The algorithm proceeds by approaching the optimal solution through the solutions of an associated set of constrained optimal design problems. The solutions of the constrained problems are recognized at each stage through the application of optimality criteria based on energy concepts. Two examples are described in which the optimal member size and layout of a truss is predicted, given the joint locations and loads.
Understanding Mechanical Design with Respect to Manufacturability
NASA Technical Reports Server (NTRS)
Mondell, Skyler
2010-01-01
At the NASA Prototype Development Laboratory in Kennedy Space Center, Fl, several projects concerning different areas of mechanical design were undertaken in order to better understand the relationship between mechanical design and manufacturabiIity. The assigned projects pertained specifically to the NASA Space Shuttle, Constellation, and Expendable Launch Vehicle programs. During the work term, mechanical design practices relating to manufacturing processes were learned and utilized in order to obtain an understanding of mechanical design with respect to manufacturability.
A VLSI design concept for parallel iterative algorithms
NASA Astrophysics Data System (ADS)
Sun, C. C.; Götze, J.
2009-05-01
Modern VLSI manufacturing technology has kept shrinking down to the nanoscale level with a very fast trend. Integration with the advanced nano-technology now makes it possible to realize advanced parallel iterative algorithms directly which was almost impossible 10 years ago. In this paper, we want to discuss the influences of evolving VLSI technologies for iterative algorithms and present design strategies from an algorithmic and architectural point of view. Implementing an iterative algorithm on a multiprocessor array, there is a trade-off between the performance/complexity of processors and the load/throughput of interconnects. This is due to the behavior of iterative algorithms. For example, we could simplify the parallel implementation of the iterative algorithm (i.e., processor elements of the multiprocessor array) in any way as long as the convergence is guaranteed. However, the modification of the algorithm (processors) usually increases the number of required iterations which also means that the switch activity of interconnects is increasing. As an example we show that a 25×25 full Jacobi EVD array could be realized into one single FPGA device with the simplified μ-rotation CORDIC architecture.
A robust Feasible Directions algorithm for design synthesis
NASA Technical Reports Server (NTRS)
Vanderplaats, G. N.
1983-01-01
A nonlinear optimization algorithm is developed which combines the best features of the Method of Feasible Directions and the Generalized Reduced Gradient Method. This algorithm utilizes the direction-finding sub-problem from the Method of Feasible Directions to find a search direction which is equivalent to that of the Generalized Reduced Gradient Method, but does not require the addition of a large number of slack variables associated with inequality constraints. This method provides a core-efficient algorithm for the solution of optimization problems with a large number of inequality constraints. Further optimization efficiency is derived by introducing the concept of infrequent gradient calculations. In addition, it is found that the sensitivity of the optimum design to changes in the problem parameters can be obtained using this method without the need for second derivatives or Lagrange multipliers. A numerical example is given in order to demonstrate the efficiency of the algorithm and the sensitivity analysis.
Designing Artificial Neural Networks Using Particle Swarm Optimization Algorithms
Garro, Beatriz A.; Vázquez, Roberto A.
2015-01-01
Artificial Neural Network (ANN) design is a complex task because its performance depends on the architecture, the selected transfer function, and the learning algorithm used to train the set of synaptic weights. In this paper we present a methodology that automatically designs an ANN using particle swarm optimization algorithms such as Basic Particle Swarm Optimization (PSO), Second Generation of Particle Swarm Optimization (SGPSO), and a New Model of PSO called NMPSO. The aim of these algorithms is to evolve, at the same time, the three principal components of an ANN: the set of synaptic weights, the connections or architecture, and the transfer functions for each neuron. Eight different fitness functions were proposed to evaluate the fitness of each solution and find the best design. These functions are based on the mean square error (MSE) and the classification error (CER) and implement a strategy to avoid overtraining and to reduce the number of connections in the ANN. In addition, the ANN designed with the proposed methodology is compared with those designed manually using the well-known Back-Propagation and Levenberg-Marquardt Learning Algorithms. Finally, the accuracy of the method is tested with different nonlinear pattern classification problems. PMID:26221132
Designing Artificial Neural Networks Using Particle Swarm Optimization Algorithms.
Garro, Beatriz A; Vázquez, Roberto A
2015-01-01
Artificial Neural Network (ANN) design is a complex task because its performance depends on the architecture, the selected transfer function, and the learning algorithm used to train the set of synaptic weights. In this paper we present a methodology that automatically designs an ANN using particle swarm optimization algorithms such as Basic Particle Swarm Optimization (PSO), Second Generation of Particle Swarm Optimization (SGPSO), and a New Model of PSO called NMPSO. The aim of these algorithms is to evolve, at the same time, the three principal components of an ANN: the set of synaptic weights, the connections or architecture, and the transfer functions for each neuron. Eight different fitness functions were proposed to evaluate the fitness of each solution and find the best design. These functions are based on the mean square error (MSE) and the classification error (CER) and implement a strategy to avoid overtraining and to reduce the number of connections in the ANN. In addition, the ANN designed with the proposed methodology is compared with those designed manually using the well-known Back-Propagation and Levenberg-Marquardt Learning Algorithms. Finally, the accuracy of the method is tested with different nonlinear pattern classification problems. PMID:26221132
Design of synthetic biological logic circuits based on evolutionary algorithm.
Chuang, Chia-Hua; Lin, Chun-Liang; Chang, Yen-Chang; Jennawasin, Tanagorn; Chen, Po-Kuei
2013-08-01
The construction of an artificial biological logic circuit using systematic strategy is recognised as one of the most important topics for the development of synthetic biology. In this study, a real-structured genetic algorithm (RSGA), which combines general advantages of the traditional real genetic algorithm with those of the structured genetic algorithm, is proposed to deal with the biological logic circuit design problem. A general model with the cis-regulatory input function and appropriate promoter activity functions is proposed to synthesise a wide variety of fundamental logic gates such as NOT, Buffer, AND, OR, NAND, NOR and XOR. The results obtained can be extended to synthesise advanced combinational and sequential logic circuits by topologically distinct connections. The resulting optimal design of these logic gates and circuits are established via the RSGA. The in silico computer-based modelling technology has been verified showing its great advantages in the purpose. PMID:23919952
Design of Automatic Extraction Algorithm of Knowledge Points for MOOCs
Chen, Haijian; Han, Dongmei; Dai, Yonghui; Zhao, Lina
2015-01-01
In recent years, Massive Open Online Courses (MOOCs) are very popular among college students and have a powerful impact on academic institutions. In the MOOCs environment, knowledge discovery and knowledge sharing are very important, which currently are often achieved by ontology techniques. In building ontology, automatic extraction technology is crucial. Because the general methods of text mining algorithm do not have obvious effect on online course, we designed automatic extracting course knowledge points (AECKP) algorithm for online course. It includes document classification, Chinese word segmentation, and POS tagging for each document. Vector Space Model (VSM) is used to calculate similarity and design the weight to optimize the TF-IDF algorithm output values, and the higher scores will be selected as knowledge points. Course documents of “C programming language” are selected for the experiment in this study. The results show that the proposed approach can achieve satisfactory accuracy rate and recall rate. PMID:26448738
OSPREY: Protein Design with Ensembles, Flexibility, and Provable Algorithms
Gainza, Pablo; Roberts, Kyle E.; Georgiev, Ivelin; Lilien, Ryan H.; Keedy, Daniel A.; Chen, Cheng-Yu; Reza, Faisal; Anderson, Amy C.; Richardson, David C.; Richardson, Jane S.; Donald, Bruce R.
2013-01-01
Summary We have developed a suite of protein redesign algorithms that improves realistic in silico modeling of proteins. These algorithms are based on three characteristics that make them unique: (1) improved flexibility of the protein backbone, protein side chains, and ligand to accurately capture the conformational changes that are induced by mutations to the protein sequence; (2) modeling of proteins and ligands as ensembles of low-energy structures to better approximate binding affinity; and (3) a globally-optimal protein design search, guaranteeing that the computational predictions are optimal with respect to the input model. Here, we illustrate the importance of these three characteristics. We then describe OSPREY, a protein redesign suite that implements our protein design algorithms. OSPREY has been used prospectively, with experimental validation, in several biomedically-relevant settings. We show in detail how OSPREY has been used to predict resistance mutations and explain why improved flexibility, ensembles, and provability are essential for this application. PMID:23422427
A superlinear interior points algorithm for engineering design optimization
NASA Technical Reports Server (NTRS)
Herskovits, J.; Asquier, J.
1990-01-01
We present a quasi-Newton interior points algorithm for nonlinear constrained optimization. It is based on a general approach consisting of the iterative solution in the primal and dual spaces of the equalities in Karush-Kuhn-Tucker optimality conditions. This is done in such a way to have primal and dual feasibility at each iteration, which ensures satisfaction of those optimality conditions at the limit points. This approach is very strong and efficient, since at each iteration it only requires the solution of two linear systems with the same matrix, instead of quadratic programming subproblems. It is also particularly appropriate for engineering design optimization inasmuch at each iteration a feasible design is obtained. The present algorithm uses a quasi-Newton approximation of the second derivative of the Lagrangian function in order to have superlinear asymptotic convergence. We discuss theoretical aspects of the algorithm and its computer implementation.
Distributed genetic algorithms for the floorplan design problem
NASA Technical Reports Server (NTRS)
Cohoon, James P.; Hegde, Shailesh U.; Martin, Worthy N.; Richards, Dana S.
1991-01-01
Designing a VLSI floorplan calls for arranging a given set of modules in the plane to minimize the weighted sum of area and wire-length measures. A method of solving the floorplan design problem using distributed genetic algorithms is presented. Distributed genetic algorithms, based on the paleontological theory of punctuated equilibria, offer a conceptual modification to the traditional genetic algorithms. Experimental results on several problem instances demonstrate the efficacy of this method and indicate the advantages of this method over other methods, such as simulated annealing. The method has performed better than the simulated annealing approach, both in terms of the average cost of the solutions found and the best-found solution, in almost all the problem instances tried.
Design of Automatic Extraction Algorithm of Knowledge Points for MOOCs.
Chen, Haijian; Han, Dongmei; Dai, Yonghui; Zhao, Lina
2015-01-01
In recent years, Massive Open Online Courses (MOOCs) are very popular among college students and have a powerful impact on academic institutions. In the MOOCs environment, knowledge discovery and knowledge sharing are very important, which currently are often achieved by ontology techniques. In building ontology, automatic extraction technology is crucial. Because the general methods of text mining algorithm do not have obvious effect on online course, we designed automatic extracting course knowledge points (AECKP) algorithm for online course. It includes document classification, Chinese word segmentation, and POS tagging for each document. Vector Space Model (VSM) is used to calculate similarity and design the weight to optimize the TF-IDF algorithm output values, and the higher scores will be selected as knowledge points. Course documents of "C programming language" are selected for the experiment in this study. The results show that the proposed approach can achieve satisfactory accuracy rate and recall rate. PMID:26448738
Design of PID-type controllers using multiobjective genetic algorithms.
Herreros, Alberto; Baeyens, Enrique; Perán, José R
2002-10-01
The design of a PID controller is a multiobjective problem. A plant and a set of specifications to be satisfied are given. The designer has to adjust the parameters of the PID controller such that the feedback interconnection of the plant and the controller satisfies the specifications. These specifications are usually competitive and any acceptable solution requires a tradeoff among them. An approach for adjusting the parameters of a PID controller based on multiobjective optimization and genetic algorithms is presented in this paper. The MRCD (multiobjective robust control design) genetic algorithm has been employed. The approach can be easily generalized to design multivariable coupled and decentralized PID loops and has been successfully validated for a large number of experimental cases. PMID:12398277
USING GENETIC ALGORITHMS TO DESIGN ENVIRONMENTALLY FRIENDLY PROCESSES
Genetic algorithm calculations are applied to the design of chemical processes to achieve improvements in environmental and economic performance. By finding the set of Pareto (i.e., non-dominated) solutions one can see how different objectives, such as environmental and economic ...
Designing an Algorithm Animation System To Support Instructional Tasks.
ERIC Educational Resources Information Center
Hamilton-Taylor, Ashley George; Kraemer, Eileen
2002-01-01
The authors are conducting a study of instructors teaching data structure and algorithm topics, with a focus on the use of diagrams and tracing. The results of this study are being used to inform the design of the Support Kit for Animation (SKA). This article describes a preliminary version of SKA, and possible usage scenarios. (Author/AEF)
Optical design with the aid of a genetic algorithm.
van Leijenhorst, D C; Lucasius, C B; Thijssen, J M
1996-01-01
Natural evolution is widely accepted as being the process underlying the design and optimization of the sensory functions of biological organisms. Using a genetic algorithm, this process is extended to the automatic optimization and design of optical systems, e.g. as used in astronomical telescopes. The results of this feasibility study indicate that various types of aberrations can be corrected quickly and simultaneously, even on small computers. PMID:8924643
Optimal design of plasmonic waveguide using multiobjective genetic algorithm
NASA Astrophysics Data System (ADS)
Jung, Jaehoon
2016-01-01
An approach for multiobjective optimal design of a plasmonic waveguide is presented. We use a multiobjective extension of a genetic algorithm to find the Pareto-optimal geometries. The design variables are the geometrical parameters of the waveguide. The objective functions are chosen as the figure of merit defined as the ratio between the propagation distance and effective mode size and the normalized coupling length between adjacent waveguides at the telecom wavelength of 1550 nm.
A new collage steganographic algorithm using cartoon design
NASA Astrophysics Data System (ADS)
Yi, Shuang; Zhou, Yicong; Pun, Chi-Man; Chen, C. L. Philip
2014-02-01
Existing collage steganographic methods suffer from low payload of embedding messages. To improve the payload while providing a high level of security protection to messages, this paper introduces a new collage steganographic algorithm using cartoon design. It embeds messages into the least significant bits (LSBs) of color cartoon objects, applies different permutations to each object, and adds objects to a cartoon cover image to obtain the stego image. Computer simulations and comparisons demonstrate that the proposed algorithm shows significantly higher capacity of embedding messages compared with existing collage steganographic methods.
Martinez-Canales, Monica L.; Heaphy, Robert; Gramacy, Robert B.; Taddy, Matt; Chiesa, Michael L.; Thomas, Stephen W.; Swiler, Laura Painton; Hough, Patricia Diane; Lee, Herbert K. H.; Trucano, Timothy Guy; Gray, Genetha Anne
2006-11-01
This project focused on research and algorithmic development in optimization under uncertainty (OUU) problems driven by earth penetrator (EP) designs. While taking into account uncertainty, we addressed three challenges in current simulation-based engineering design and analysis processes. The first challenge required leveraging small local samples, already constructed by optimization algorithms, to build effective surrogate models. We used Gaussian Process (GP) models to construct these surrogates. We developed two OUU algorithms using 'local' GPs (OUU-LGP) and one OUU algorithm using 'global' GPs (OUU-GGP) that appear competitive or better than current methods. The second challenge was to develop a methodical design process based on multi-resolution, multi-fidelity models. We developed a Multi-Fidelity Bayesian Auto-regressive process (MF-BAP). The third challenge involved the development of tools that are computational feasible and accessible. We created MATLAB{reg_sign} and initial DAKOTA implementations of our algorithms.
Design of transonic airfoils and wings using a hybrid design algorithm
NASA Technical Reports Server (NTRS)
Campbell, Richard L.; Smith, Leigh A.
1987-01-01
A method has been developed for designing airfoils and wings at transonic speeds. It utilizes a hybrid design algorithm in an iterative predictor/corrector approach, alternating between analysis code and a design module. This method has been successfully applied to a variety of airfoil and wing design problems, including both transport and highly-swept fighter wing configurations. An efficient approach to viscous airfoild design and the effect of including static aeroelastic deflections in the wing design process are also illustrated.
Mechanical verification of a schematic Byzantine clock synchronization algorithm
NASA Technical Reports Server (NTRS)
Shankar, Natarajan
1991-01-01
Schneider generalizes a number of protocols for Byzantine fault tolerant clock synchronization and presents a uniform proof for their correctness. The authors present a machine checked proof of this schematic protocol that revises some of the details in Schneider's original analysis. The verification was carried out with the EHDM system developed at the SRI Computer Science Laboratory. The mechanically checked proofs include the verification that the egocentric mean function used in Lamport and Melliar-Smith's Interactive Convergence Algorithm satisfies the requirements of Schneider's protocol.
Full design of fuzzy controllers using genetic algorithms
NASA Technical Reports Server (NTRS)
Homaifar, Abdollah; Mccormick, ED
1992-01-01
This paper examines the applicability of genetic algorithms (GA) in the complete design of fuzzy logic controllers. While GA has been used before in the development of rule sets or high performance membership functions, the interdependence between these two components dictates that they should be designed together simultaneously. GA is fully capable of creating complete fuzzy controllers given the equations of motion of the system, eliminating the need for human input in the design loop. We show the application of this new method to the development of a cart controller.
A new algorithm for modeling friction in dynamic mechanical systems
NASA Technical Reports Server (NTRS)
Hill, R. E.
1988-01-01
A method of modeling friction forces that impede the motion of parts of dynamic mechanical systems is described. Conventional methods in which the friction effect is assumed a constant force, or torque, in a direction opposite to the relative motion, are applicable only to those cases where applied forces are large in comparison to the friction, and where there is little interest in system behavior close to the times of transitions through zero velocity. An algorithm is described that provides accurate determination of friction forces over a wide range of applied force and velocity conditions. The method avoids the simulation errors resulting from a finite integration interval used in connection with a conventional friction model, as is the case in many digital computer-based simulations. The algorithm incorporates a predictive calculation based on initial conditions of motion, externally applied forces, inertia, and integration step size. The predictive calculation in connection with an external integration process provides an accurate determination of both static and Coulomb friction forces and resulting motions in dynamic simulations. Accuracy of the results is improved over that obtained with conventional methods and a relatively large integration step size is permitted. A function block for incorporation in a specific simulation program is described. The general form of the algorithm facilitates implementation with various programming languages such as FORTRAN or C, as well as with other simulation programs.
Entropy-Based Search Algorithm for Experimental Design
NASA Astrophysics Data System (ADS)
Malakar, N. K.; Knuth, K. H.
2011-03-01
The scientific method relies on the iterated processes of inference and inquiry. The inference phase consists of selecting the most probable models based on the available data; whereas the inquiry phase consists of using what is known about the models to select the most relevant experiment. Optimizing inquiry involves searching the parameterized space of experiments to select the experiment that promises, on average, to be maximally informative. In the case where it is important to learn about each of the model parameters, the relevance of an experiment is quantified by Shannon entropy of the distribution of experimental outcomes predicted by a probable set of models. If the set of potential experiments is described by many parameters, we must search this high-dimensional entropy space. Brute force search methods will be slow and computationally expensive. We present an entropy-based search algorithm, called nested entropy sampling, to select the most informative experiment for efficient experimental design. This algorithm is inspired by Skilling's nested sampling algorithm used in inference and borrows the concept of a rising threshold while a set of experiment samples are maintained. We demonstrate that this algorithm not only selects highly relevant experiments, but also is more efficient than brute force search. Such entropic search techniques promise to greatly benefit autonomous experimental design.
A disturbance based control/structure design algorithm
NASA Technical Reports Server (NTRS)
Mclaren, Mark D.; Slater, Gary L.
1989-01-01
Some authors take a classical approach to the simultaneous structure/control optimization by attempting to simultaneously minimize the weighted sum of the total mass and a quadratic form, subject to all of the structural and control constraints. Here, the optimization will be based on the dynamic response of a structure to an external unknown stochastic disturbance environment. Such a response to excitation approach is common to both the structural and control design phases, and hence represents a more natural control/structure optimization strategy than relying on artificial and vague control penalties. The design objective is to find the structure and controller of minimum mass such that all the prescribed constraints are satisfied. Two alternative solution algorithms are presented which have been applied to this problem. Each algorithm handles the optimization strategy and the imposition of the nonlinear constraints in a different manner. Two controller methodologies, and their effect on the solution algorithm, will be considered. These are full state feedback and direct output feedback, although the problem formulation is not restricted solely to these forms of controller. In fact, although full state feedback is a popular choice among researchers in this field (for reasons that will become apparent), its practical application is severely limited. The controller/structure interaction is inserted by the imposition of appropriate closed-loop constraints, such as closed-loop output response and control effort constraints. Numerical results will be obtained for a representative flexible structure model to illustrate the effectiveness of the solution algorithms.
Algorithm Of Revitalization Programme Design For Housing Estates
NASA Astrophysics Data System (ADS)
Ostańska, Anna
2015-09-01
Demographic problems, obsolescence of existing buildings, unstable economy, as well as misunderstanding of the mechanism that turn city quarters into areas in need for intervention result in the implementation of improvement measures that prove inadequate. The paper puts forward an algorithm of revitalization program for housing developments and presents its implementation. It also showed the effects of periodically run (10 years) three-way diagnostic tests in correlation with the concept of settlement management.
Designing a competent simple genetic algorithm for search and optimization
NASA Astrophysics Data System (ADS)
Reed, Patrick; Minsker, Barbara; Goldberg, David E.
2000-12-01
Simple genetic algorithms have been used to solve many water resources problems, but specifying the parameters that control how adaptive search is performed can be a difficult and time-consuming trial-and-error process. However, theoretical relationships for population sizing and timescale analysis have been developed that can provide pragmatic tools for vastly limiting the number of parameter combinations that must be considered. The purpose of this technical note is to summarize these relationships for the water resources community and to illustrate their practical utility in a long-term groundwater monitoring design application. These relationships, which model the effects of the primary operators of a simple genetic algorithm (selection, recombination, and mutation), provide a highly efficient method for ensuring convergence to near-optimal or optimal solutions. Application of the method to a monitoring design test case identified robust parameter values using only three trial runs.
Mechanical considerations and design skills.
Alvis, Robert L.
2008-03-01
The purpose of the report is to provide experienced-based insights into design processes that will benefit designers beginning their employment at Sandia National Laboratories or those assuming new design responsibilities. The main purpose of this document is to provide engineers with the practical aspects of system design. The material discussed here may not be new to some readers, but some of it was to me. Transforming an idea to a design to solve a problem is a skill, and skills are similar to history lessons. We gain these skills from experience, and many of us have not been fortunate enough to grow in an environment that provided the skills that we now need. I was fortunate to grow up on a farm where we had to learn how to maintain and operate several different kinds of engines and machines. If you are like me, my formal experience is partially based upon the two universities from which I graduated, where few practical applications of the technologies were taught. What was taught was mainly theoretical, and few instructors had practical experience to offer the students. I understand this, as students have their hands full just to learn the theoretical. The practical part was mainly left up to 'on the job experience'. However, I believe it is better to learn the practical applications early and apply them quickly 'on the job'. System design engineers need to know several technical things, both in and out of their field of expertise. An engineer is not expected to know everything, but he should know when to ask an expert for assistance. This 'expert' can be in any field, whether it is in analyses, drafting, machining, material properties, testing, etc. The best expert is a person who has practical experience in the area of needed information, and consulting with that individual can be the best and quickest way for one to learn. If the information provided here can improve your design skills and save one design from having a problem, save cost of development, or
Application of a genetic algorithm to wind turbine design
Selig, M.S.; Coverstone-Carroll, V.L.
1995-09-01
This paper presents an optimization procedure for stall-regulated horizontal-axis wind-turbines. A hybrid approach is used that combines the advantages of a genetic algorithm and an inverse design method. This method is used to determine the optimum blade pitch and blade chord and twist distributions that maximize the annual energy production. To illustrate the method, a family of 25 wind turbines was designed to examine the sensitivity of annual energy production to changes in the rotor blade length and peak rotor power. Trends are revealed that should aid in the design of new rotors for existing turbines. In the second application, a series of five wind turbines was designed to determine the benefits of specifically tailoring wind turbine blades for the average wind speed at a particular site. The results have important practical implications related to rotors designed for the Midwest versus those where the average wind speed may be greater.
Efficient computer algebra algorithms for polynomial matrices in control design
NASA Technical Reports Server (NTRS)
Baras, J. S.; Macenany, D. C.; Munach, R.
1989-01-01
The theory of polynomial matrices plays a key role in the design and analysis of multi-input multi-output control and communications systems using frequency domain methods. Examples include coprime factorizations of transfer functions, cannonical realizations from matrix fraction descriptions, and the transfer function design of feedback compensators. Typically, such problems abstract in a natural way to the need to solve systems of Diophantine equations or systems of linear equations over polynomials. These and other problems involving polynomial matrices can in turn be reduced to polynomial matrix triangularization procedures, a result which is not surprising given the importance of matrix triangularization techniques in numerical linear algebra. Matrices with entries from a field and Gaussian elimination play a fundamental role in understanding the triangularization process. In the case of polynomial matrices, matrices with entries from a ring for which Gaussian elimination is not defined and triangularization is accomplished by what is quite properly called Euclidean elimination. Unfortunately, the numerical stability and sensitivity issues which accompany floating point approaches to Euclidean elimination are not very well understood. New algorithms are presented which circumvent entirely such numerical issues through the use of exact, symbolic methods in computer algebra. The use of such error-free algorithms guarantees that the results are accurate to within the precision of the model data--the best that can be hoped for. Care must be taken in the design of such algorithms due to the phenomenon of intermediate expressions swell.
Orthogonalizing EM: A design-based least squares algorithm
Xiong, Shifeng; Dai, Bin; Huling, Jared; Qian, Peter Z. G.
2016-01-01
We introduce an efficient iterative algorithm, intended for various least squares problems, based on a design of experiments perspective. The algorithm, called orthogonalizing EM (OEM), works for ordinary least squares and can be easily extended to penalized least squares. The main idea of the procedure is to orthogonalize a design matrix by adding new rows and then solve the original problem by embedding the augmented design in a missing data framework. We establish several attractive theoretical properties concerning OEM. For the ordinary least squares with a singular regression matrix, an OEM sequence converges to the Moore-Penrose generalized inverse-based least squares estimator. For ordinary and penalized least squares with various penalties, it converges to a point having grouping coherence for fully aliased regression matrices. Convergence and the convergence rate of the algorithm are examined. Finally, we demonstrate that OEM is highly efficient for large-scale least squares and penalized least squares problems, and is considerably faster than competing methods when n is much larger than p. Supplementary materials for this article are available online. PMID:27499558
Robust Optimization Design Algorithm for High-Frequency TWTs
NASA Technical Reports Server (NTRS)
Wilson, Jeffrey D.; Chevalier, Christine T.
2010-01-01
Traveling-wave tubes (TWTs), such as the Ka-band (26-GHz) model recently developed for the Lunar Reconnaissance Orbiter, are essential as communication amplifiers in spacecraft for virtually all near- and deep-space missions. This innovation is a computational design algorithm that, for the first time, optimizes the efficiency and output power of a TWT while taking into account the effects of dimensional tolerance variations. Because they are primary power consumers and power generation is very expensive in space, much effort has been exerted over the last 30 years to increase the power efficiency of TWTs. However, at frequencies higher than about 60 GHz, efficiencies of TWTs are still quite low. A major reason is that at higher frequencies, dimensional tolerance variations from conventional micromachining techniques become relatively large with respect to the circuit dimensions. When this is the case, conventional design- optimization procedures, which ignore dimensional variations, provide inaccurate designs for which the actual amplifier performance substantially under-performs that of the design. Thus, this new, robust TWT optimization design algorithm was created to take account of and ameliorate the deleterious effects of dimensional variations and to increase efficiency, power, and yield of high-frequency TWTs. This design algorithm can help extend the use of TWTs into the terahertz frequency regime of 300-3000 GHz. Currently, these frequencies are under-utilized because of the lack of efficient amplifiers, thus this regime is known as the "terahertz gap." The development of an efficient terahertz TWT amplifier could enable breakthrough applications in space science molecular spectroscopy, remote sensing, nondestructive testing, high-resolution "through-the-wall" imaging, biomedical imaging, and detection of explosives and toxic biochemical agents.
Thrust vector control algorithm design for the Cassini spacecraft
NASA Technical Reports Server (NTRS)
Enright, Paul J.
1993-01-01
This paper describes a preliminary design of the thrust vector control algorithm for the interplanetary spacecraft, Cassini. Topics of discussion include flight software architecture, modeling of sensors, actuators, and vehicle dynamics, and controller design and analysis via classical methods. Special attention is paid to potential interactions with structural flexibilities and propellant dynamics. Controller performance is evaluated in a simulation environment built around a multi-body dynamics model, which contains nonlinear models of the relevant hardware and preliminary versions of supporting attitude determination and control functions.
A Matrix-Free Algorithm for Multidisciplinary Design Optimization
NASA Astrophysics Data System (ADS)
Lambe, Andrew Borean
Multidisciplinary design optimization (MDO) is an approach to engineering design that exploits the coupling between components or knowledge disciplines in a complex system to improve the final product. In aircraft design, MDO methods can be used to simultaneously design the outer shape of the aircraft and the internal structure, taking into account the complex interaction between the aerodynamic forces and the structural flexibility. Efficient strategies are needed to solve such design optimization problems and guarantee convergence to an optimal design. This work begins with a comprehensive review of MDO problem formulations and solution algorithms. First, a fundamental MDO problem formulation is defined from which other formulations may be obtained through simple transformations. Using these fundamental problem formulations, decomposition methods from the literature are reviewed and classified. All MDO methods are presented in a unified mathematical notation to facilitate greater understanding. In addition, a novel set of diagrams, called extended design structure matrices, are used to simultaneously visualize both data communication and process flow between the many software components of each method. For aerostructural design optimization, modern decomposition-based MDO methods cannot efficiently handle the tight coupling between the aerodynamic and structural states. This fact motivates the exploration of methods that can reduce the computational cost. A particular structure in the direct and adjoint methods for gradient computation motivates the idea of a matrix-free optimization method. A simple matrix-free optimizer is developed based on the augmented Lagrangian algorithm. This new matrix-free optimizer is tested on two structural optimization problems and one aerostructural optimization problem. The results indicate that the matrix-free optimizer is able to efficiently solve structural and multidisciplinary design problems with thousands of variables and
A Matrix-Free Algorithm for Multidisciplinary Design Optimization
NASA Astrophysics Data System (ADS)
Lambe, Andrew Borean
Multidisciplinary design optimization (MDO) is an approach to engineering design that exploits the coupling between components or knowledge disciplines in a complex system to improve the final product. In aircraft design, MDO methods can be used to simultaneously design the outer shape of the aircraft and the internal structure, taking into account the complex interaction between the aerodynamic forces and the structural flexibility. Efficient strategies are needed to solve such design optimization problems and guarantee convergence to an optimal design. This work begins with a comprehensive review of MDO problem formulations and solution algorithms. First, a fundamental MDO problem formulation is defined from which other formulations may be obtained through simple transformations. Using these fundamental problem formulations, decomposition methods from the literature are reviewed and classified. All MDO methods are presented in a unified mathematical notation to facilitate greater understanding. In addition, a novel set of diagrams, called extended design structure matrices, are used to simultaneously visualize both data communication and process flow between the many software components of each method. For aerostructural design optimization, modern decomposition-based MDO methods cannot efficiently handle the tight coupling between the aerodynamic and structural states. This fact motivates the exploration of methods that can reduce the computational cost. A particular structure in the direct and adjoint methods for gradient computation. motivates the idea of a matrix-free optimization method. A simple matrix-free optimizer is developed based on the augmented Lagrangian algorithm. This new matrix-free optimizer is tested on two structural optimization problems and one aerostructural optimization problem. The results indicate that the matrix-free optimizer is able to efficiently solve structural and multidisciplinary design problems with thousands of variables and
An efficient parallel algorithm for accelerating computational protein design
Zhou, Yichao; Xu, Wei; Donald, Bruce R.; Zeng, Jianyang
2014-01-01
Motivation: Structure-based computational protein design (SCPR) is an important topic in protein engineering. Under the assumption of a rigid backbone and a finite set of discrete conformations of side-chains, various methods have been proposed to address this problem. A popular method is to combine the dead-end elimination (DEE) and A* tree search algorithms, which provably finds the global minimum energy conformation (GMEC) solution. Results: In this article, we improve the efficiency of computing A* heuristic functions for protein design and propose a variant of A* algorithm in which the search process can be performed on a single GPU in a massively parallel fashion. In addition, we make some efforts to address the memory exceeding problem in A* search. As a result, our enhancements can achieve a significant speedup of the A*-based protein design algorithm by four orders of magnitude on large-scale test data through pre-computation and parallelization, while still maintaining an acceptable memory overhead. We also show that our parallel A* search algorithm could be successfully combined with iMinDEE, a state-of-the-art DEE criterion, for rotamer pruning to further improve SCPR with the consideration of continuous side-chain flexibility. Availability: Our software is available and distributed open-source under the GNU Lesser General License Version 2.1 (GNU, February 1999). The source code can be downloaded from http://www.cs.duke.edu/donaldlab/osprey.php or http://iiis.tsinghua.edu.cn/∼compbio/software.html. Contact: zengjy321@tsinghua.edu.cn Supplementary information: Supplementary data are available at Bioinformatics online. PMID:24931991
Algorithm development for the control design of flexible structures
NASA Technical Reports Server (NTRS)
Skelton, R. E.
1983-01-01
The critical problems associated with the control of highly damped flexible structures are outlined. The practical problems include: high performance; assembly in space, configuration changes; on-line controller software design; and lack of test data. Underlying all of these problems is the central problem of modeling errors. To justify the expense of a space structure, the performance requirements will necessarily be very severe. On the other hand, the absence of economical tests precludes the availability of reliable data before flight. A design algorithm is offered which: (1) provides damping for a larger number of modes than the optimal attitude controller controls; (2) coordinates the rate of feedback design with the attitude control design by use of a similar cost function; and (3) provides model reduction and controller reduction decisions which are systematically connected to the mathematical statement of the control objectives and the disturbance models.
Linear vs. function-based dose algorithm designs.
Stanford, N
2011-03-01
The performance requirements prescribed in IEC 62387-1, 2007 recommend linear, additive algorithms for external dosimetry [IEC. Radiation protection instrumentation--passive integrating dosimetry systems for environmental and personal monitoring--Part 1: General characteristics and performance requirements. IEC 62387-1 (2007)]. Neither of the two current standards for performance of external dosimetry in the USA address the additivity of dose results [American National Standards Institute, Inc. American National Standard for dosimetry personnel dosimetry performance criteria for testing. ANSI/HPS N13.11 (2009); Department of Energy. Department of Energy Standard for the performance testing of personnel dosimetry systems. DOE/EH-0027 (1986)]. While there are significant merits to adopting a purely linear solution to estimating doses from multi-element external dosemeters, differences in the standards result in technical as well as perception challenges in designing a single algorithm approach that will satisfy both IEC and USA external dosimetry performance requirements. The dosimetry performance testing standards in the USA do not incorporate type testing, but rely on biennial performance tests to demonstrate proficiency in a wide range of pure and mixed fields. The test results are used exclusively to judge the system proficiency, with no specific requirements on the algorithm design. Technical challenges include mixed beta/photon fields with a beta dose as low as 0.30 mSv mixed with 0.05 mSv of low-energy photons. Perception-based challenges, resulting from over 20 y of experience with this type of performance testing in the USA, include the common belief that the overall quality of the dosemeter performance can be judged from performance to pure fields. This paper presents synthetic testing results from currently accredited function-based algorithms and new developed purely linear algorithms. A comparison of the performance data highlights the benefits of each
Conceptual space Systems Design using Meta-Heuristic Algorithms
NASA Astrophysics Data System (ADS)
Kim, Byoungsoo; Morgenthaler, George W.
2002-01-01
easily and explicitly by new design-to-cost philosophy, "faster, better, cheaper" (fast-track, innovative, lower-cost, small-sat). The objective of the Space Systems Design has moved from maximizing space mission performance under weak time and cost constraints (almost regardless of cost) but with technology risk constraints, to maximizing mission goals under cost and schedule constraints but with prudent technology risk constraints, or maximizing space mission performance per unit cost. Within this mindset, Conceptual Space Systems Design models were formulated as constrained combinatorial optimization problems with estimated Total Mission Cost (TMC) as its objective function to be minimized and subsystems trade-offs as decision variables in its design space, using parametric estimating relationships (PERs) and cost estimating relationships (CERs).Here a constrained combinatorial optimized "solution" is defined as achieving the most favorable alternative for the system on the basis of the decision-making design criteria. Two non-traditional meta-heuristic optimization algorithms, Genetic Algorithms (GAs) and Simulated Annealing (SA), were used to solve the formulated combinatorial optimization model for the Conceptual Space Systems Design. GAs and SA were demonstrated on SAMPEX. The model simulation statistics show that the estimated TMCs obtained by GAs and SA are statistically equal and consistent. These statistics also show that Conceptual Space Systems Design Model can be used as a guidance tool to evaluate and validate space research proposals. Also, the non-traditional meta-heuristic constrained optimization techniques, GAs and SA, can be applied to all manner of space, civil or commercial design problems.
Hernández-Ocaña, Betania; Pozos-Parra, Ma Del Pilar; Mezura-Montes, Efrén; Portilla-Flores, Edgar Alfredo; Vega-Alvarado, Eduardo; Calva-Yáñez, Maria Bárbara
2016-01-01
This paper presents two-swim operators to be added to the chemotaxis process of the modified bacterial foraging optimization algorithm to solve three instances of the synthesis of four-bar planar mechanisms. One swim favors exploration while the second one promotes fine movements in the neighborhood of each bacterium. The combined effect of the new operators looks to increase the production of better solutions during the search. As a consequence, the ability of the algorithm to escape from local optimum solutions is enhanced. The algorithm is tested through four experiments and its results are compared against two BFOA-based algorithms and also against a differential evolution algorithm designed for mechanical design problems. The overall results indicate that the proposed algorithm outperforms other BFOA-based approaches and finds highly competitive mechanisms, with a single set of parameter values and with less evaluations in the first synthesis problem, with respect to those mechanisms obtained by the differential evolution algorithm, which needed a parameter fine-tuning process for each optimization problem. PMID:27057156
Hernández-Ocaña, Betania; Pozos-Parra, Ma. Del Pilar; Mezura-Montes, Efrén; Portilla-Flores, Edgar Alfredo; Vega-Alvarado, Eduardo; Calva-Yáñez, Maria Bárbara
2016-01-01
This paper presents two-swim operators to be added to the chemotaxis process of the modified bacterial foraging optimization algorithm to solve three instances of the synthesis of four-bar planar mechanisms. One swim favors exploration while the second one promotes fine movements in the neighborhood of each bacterium. The combined effect of the new operators looks to increase the production of better solutions during the search. As a consequence, the ability of the algorithm to escape from local optimum solutions is enhanced. The algorithm is tested through four experiments and its results are compared against two BFOA-based algorithms and also against a differential evolution algorithm designed for mechanical design problems. The overall results indicate that the proposed algorithm outperforms other BFOA-based approaches and finds highly competitive mechanisms, with a single set of parameter values and with less evaluations in the first synthesis problem, with respect to those mechanisms obtained by the differential evolution algorithm, which needed a parameter fine-tuning process for each optimization problem. PMID:27057156
Neural-network-biased genetic algorithms for materials design
NASA Astrophysics Data System (ADS)
Patra, Tarak; Meenakshisundaram, Venkatesh; Simmons, David
Machine learning tools have been progressively adopted by the materials science community to accelerate design of materials with targeted properties. However, in the search for new materials exhibiting properties and performance beyond that previously achieved, machine learning approaches are frequently limited by two major shortcomings. First, they are intrinsically interpolative. They are therefore better suited to the optimization of properties within the known range of accessible behavior than to the discovery of new materials with extremal behavior. Second, they require the availability of large datasets, which in some fields are not available and would be prohibitively expensive to produce. Here we describe a new strategy for combining genetic algorithms, neural networks and other machine learning tools, and molecular simulation to discover materials with extremal properties in the absence of pre-existing data. Predictions from progressively constructed machine learning tools are employed to bias the evolution of a genetic algorithm, with fitness evaluations performed via direct molecular dynamics simulation. We survey several initial materials design problems we have addressed with this framework and compare its performance to that of standard genetic algorithm approaches. We acknowledge the W. M. Keck Foundation for support of this work.
The Mechanical Design of Nacre
NASA Astrophysics Data System (ADS)
Jackson, A. P.; Vincent, J. F. V.; Turner, R. M.
1988-09-01
Mother-of-pearl (nacre) is a platelet-reinforced composite, highly filled with calcium carbonate (aragonite). The Young modulus, determined from beams of a span-to-depth ratio of no less than 15 (a necessary precaution), is of the order of 70 GPa (dry) and 60 GPa (wet), much higher than previously recorded values. These values can be derived from `shear-lag' models developed for platey composites, suggesting that nacre is a near-ideal material. The tensile strength of nacre is of the order of 170 MPa (dry) and 140 MPa (wet), values which are best modelled assuming that pull-out of the platelets is the main mode of failure. In three-point bending, depending on the span-to-depth ratio and degree of hydration, the work to fracture across the platelets varies from 350 to 1240 J m-2. In general, the effect of water is to increase the ductility of nacre and increase the toughness almost tenfold by the associated introduction of plastic work. The pull-out model is sufficient to account for the toughness of dry nacre, but accounts for only a third of the toughness of wet nacre. The additional contribution probably comes from debonding within the thin layer of matrix material. Electron microscopy reveals that the ductility of wet nacre is caused by cohesive fracture along platelet lamellae at right angles to the main crack. The matrix appears to be well bonded to the lamellae, enabling the matrix to be stretched across the delamination cracks without breaking, thereby sustaining a force across a wider crack. Such a mechanism also explains why toughness is dependent on the span-to-depth ratio of the test piece. With this last observation as a possible exception, nacre does not employ any really novel mechanisms to achieve its mechanical properties. It is simply `well made'. The importance of nacre to the mollusc depends both on the material and the size of the shell. Catastrophic failure will be very likely in whole, undamaged shells which behave like unnotched beams at
Direct simulation Monte Carlo method with a focal mechanism algorithm
NASA Astrophysics Data System (ADS)
Rachman, Asep Nur; Chung, Tae Woong; Yoshimoto, Kazuo; Yun, Sukyoung
2015-01-01
To simulate the observation of the radiation pattern of an earthquake, the direct simulation Monte Carlo (DSMC) method is modified by implanting a focal mechanism algorithm. We compare the results of the modified DSMC method (DSMC-2) with those of the original DSMC method (DSMC-1). DSMC-2 shows more or similarly reliable results compared to those of DSMC-1, for events with 12 or more recorded stations, by weighting twice for hypocentral distance of less than 80 km. Not only the number of stations, but also other factors such as rough topography, magnitude of event, and the analysis method influence the reliability of DSMC-2. The most reliable result by DSMC-2 is obtained by the best azimuthal coverage by the largest number of stations. The DSMC-2 method requires shorter time steps and a larger number of particles than those of DSMC-1 to capture a sufficient number of arrived particles in the small-sized receiver.
ARGOS laser system mechanical design
NASA Astrophysics Data System (ADS)
Deysenroth, M.; Honsberg, M.; Gemperlein, H.; Ziegleder, J.; Raab, W.; Rabien, S.; Barl, L.; Gässler, W.; Borelli, J. L.
2014-07-01
ARGOS, a multi-star adaptive optics system is designed for the wide-field imager and multi-object spectrograph LUCI on the LBT (Large Binocular Telescope). Based on Rayleigh scattering the laser constellation images 3 artificial stars (at 532 nm) per each of the 2 eyes of the LBT, focused at a height of 12 km (Ground Layer Adaptive Optics). The stars are nominally positioned on a circle 2' in radius, but each star can be moved by up to 0.5' in any direction. For all of these needs are following main subsystems necessary: 1. A laser system with its 3 Lasers (Nd:YAG ~18W each) for delivering strong collimated light as for LGS indispensable. 2. The Launch system to project 3 beams per main mirror as a 40 cm telescope to the sky. 3. The Wave Front Sensor with a dichroic mirror. 4. The dichroic mirror unit to grab and interpret the data. 5. A Calibration Unit to adjust the system independently also during day time. 6. Racks + platforms for the WFS units. 7. Platforms and ladders for a secure access. This paper should mainly demonstrate how the ARGOS Laser System is configured and designed to support all other systems.
Multidisciplinary Multiobjective Optimal Design for Turbomachinery Using Evolutionary Algorithm
NASA Technical Reports Server (NTRS)
2005-01-01
This report summarizes Dr. Lian s efforts toward developing a robust and efficient tool for multidisciplinary and multi-objective optimal design for turbomachinery using evolutionary algorithms. This work consisted of two stages. The first stage (from July 2003 to June 2004) Dr. Lian focused on building essential capabilities required for the project. More specifically, Dr. Lian worked on two subjects: an enhanced genetic algorithm (GA) and an integrated optimization system with a GA and a surrogate model. The second stage (from July 2004 to February 2005) Dr. Lian formulated aerodynamic optimization and structural optimization into a multi-objective optimization problem and performed multidisciplinary and multi-objective optimizations on a transonic compressor blade based on the proposed model. Dr. Lian s numerical results showed that the proposed approach can effectively reduce the blade weight and increase the stage pressure ratio in an efficient manner. In addition, the new design was structurally safer than the original design. Five conference papers and three journal papers were published on this topic by Dr. Lian.
Design principles and algorithms for automated air traffic management
NASA Technical Reports Server (NTRS)
Erzberger, Heinz
1995-01-01
This paper presents design principles and algorithm for building a real time scheduler. The primary objective of the scheduler is to assign arrival aircraft to a favorable landing runway and schedule them to land at times that minimize delays. A further objective of the scheduler is to allocate delays between high altitude airspace far from the airport and low altitude airspace near the airport. A method of delay allocation is described that minimizes the average operating cost in the presence of errors in controlling aircraft to a specified landing time.
Conceptual space systems design using meta-heuristic algorithms
NASA Astrophysics Data System (ADS)
Kim, Byoungsoo
criteria. Two meta-heuristic optimization algorithms, Genetic Algorithms (GAs) and Simulated Annealing (SA), were used to optimize the formulated (simply bounded) Constrained Combinatorial Conceptual Space Systems Design Model. GAs and SA were demonstrated on the SAMPEX (Solar Anomalous & Magnetospheric Particle Explorer) Space System. The Conceptual Space Systems Design Model developed in this thesis can be used as an assessment tool to evaluate and validate Space System proposals.
Design Principles and Algorithms for Air Traffic Arrival Scheduling
NASA Technical Reports Server (NTRS)
Erzberger, Heinz; Itoh, Eri
2014-01-01
This report presents design principles and algorithms for building a real-time scheduler of arrival aircraft based on a first-come-first-served (FCFS) scheduling protocol. The algorithms provide the conceptual and computational foundation for the Traffic Management Advisor (TMA) of the Center/terminal radar approach control facilities (TRACON) automation system, which comprises a set of decision support tools for managing arrival traffic at major airports in the United States. The primary objective of the scheduler is to assign arrival aircraft to a favorable landing runway and schedule them to land at times that minimize delays. A further objective of the scheduler is to allocate delays between high-altitude airspace far away from the airport and low-altitude airspace near the airport. A method of delay allocation is described that minimizes the average operating cost in the presence of errors in controlling aircraft to a specified landing time. This report is a revision of an earlier paper first presented as part of an Advisory Group for Aerospace Research and Development (AGARD) lecture series in September 1995. The authors, during vigorous discussions over the details of this paper, felt it was important to the air-trafficmanagement (ATM) community to revise and extend the original 1995 paper, providing more detail and clarity and thereby allowing future researchers to understand this foundational work as the basis for the TMA's scheduling algorithms.
Drought Adaptation Mechanisms Should Guide Experimental Design.
Gilbert, Matthew E; Medina, Viviana
2016-08-01
The mechanism, or hypothesis, of how a plant might be adapted to drought should strongly influence experimental design. For instance, an experiment testing for water conservation should be distinct from a damage-tolerance evaluation. We define here four new, general mechanisms for plant adaptation to drought such that experiments can be more easily designed based upon the definitions. A series of experimental methods are suggested together with appropriate physiological measurements related to the drought adaptation mechanisms. The suggestion is made that the experimental manipulation should match the rate, length, and severity of soil water deficit (SWD) necessary to test the hypothesized type of drought adaptation mechanism. PMID:27090148
Algorithm To Design Finite-Field Normal-Basis Multipliers
NASA Technical Reports Server (NTRS)
Wang, Charles C.
1988-01-01
Way found to exploit Massey-Omura multiplication algorithm. Generalized algorithm locates normal basis in Galois filed GF(2m) and enables development of another algorithm to construct product function.
Ishibuchi, Hisao; Sudo, Takahiko; Nojima, Yusuke
2016-01-01
In interactive evolutionary computation (IEC), each solution is evaluated by a human user. Usually the total number of examined solutions is very small. In some applications such as hearing aid design and music composition, only a single solution can be evaluated at a time by a human user. Moreover, accurate and precise numerical evaluation is difficult. Based on these considerations, we formulated an IEC model with the minimum requirement for fitness evaluation ability of human users under the following assumptions: They can evaluate only a single solution at a time, they can memorize only a single previous solution they have just evaluated, their evaluation result on the current solution is whether it is better than the previous one or not, and the best solution among the evaluated ones should be identified after a pre-specified number of evaluations. In this paper, we first explain our IEC model in detail. Next we propose a ([Formula: see text])ES-style algorithm for our IEC model. Then we propose an offline meta-level approach to automated algorithm design for our IEC model. The main feature of our approach is the use of a different mechanism (e.g., mutation, crossover, random initialization) to generate each solution to be evaluated. Through computational experiments on test problems, our approach is compared with the ([Formula: see text])ES-style algorithm where a solution generation mechanism is pre-specified and fixed throughout the execution of the algorithm. PMID:27026888
Application of Simulated Annealing and Related Algorithms to TWTA Design
NASA Technical Reports Server (NTRS)
Radke, Eric M.
2004-01-01
Simulated Annealing (SA) is a stochastic optimization algorithm used to search for global minima in complex design surfaces where exhaustive searches are not computationally feasible. The algorithm is derived by simulating the annealing process, whereby a solid is heated to a liquid state and then cooled slowly to reach thermodynamic equilibrium at each temperature. The idea is that atoms in the solid continually bond and re-bond at various quantum energy levels, and with sufficient cooling time they will rearrange at the minimum energy state to form a perfect crystal. The distribution of energy levels is given by the Boltzmann distribution: as temperature drops, the probability of the presence of high-energy bonds decreases. In searching for an optimal design, local minima and discontinuities are often present in a design surface. SA presents a distinct advantage over other optimization algorithms in its ability to escape from these local minima. Just as high-energy atomic configurations are visited in the actual annealing process in order to eventually reach the minimum energy state, in SA highly non-optimal configurations are visited in order to find otherwise inaccessible global minima. The SA algorithm produces a Markov chain of points in the design space at each temperature, with a monotonically decreasing temperature. A random point is started upon, and the objective function is evaluated at that point. A stochastic perturbation is then made to the parameters of the point to arrive at a proposed new point in the design space, at which the objection function is evaluated as well. If the change in objective function values (Delta)E is negative, the proposed new point is accepted. If (Delta)E is positive, the proposed new point is accepted according to the Metropolis criterion: rho((Delta)f) = exp((-Delta)E/T), where T is the temperature for the current Markov chain. The process then repeats for the remainder of the Markov chain, after which the temperature is
Evolutionary Design of Rule Changing Artificial Society Using Genetic Algorithms
NASA Astrophysics Data System (ADS)
Wu, Yun; Kanoh, Hitoshi
Socioeconomic phenomena, cultural progress and political organization have recently been studied by creating artificial societies consisting of simulated agents. In this paper we propose a new method to design action rules of agents in artificial society that can realize given requests using genetic algorithms (GAs). In this paper we propose an efficient method for designing the action rules of agents that will constitute an artificial society that meets a specified demand by using a GAs. In the proposed method, each chromosome in the GA population represents a candidate set of action rules and the number of rule iterations. While a conventional method applies distinct rules in order of precedence, the present method applies a set of rules repeatedly for a certain period. The present method is aiming at both firm evolution of agent population and continuous action by that. Experimental results using the artificial society proved that the present method can generate artificial society which fills a demand in high probability.
Optimal Design of RF Energy Harvesting Device Using Genetic Algorithm
NASA Astrophysics Data System (ADS)
Mori, T.; Sato, Y.; Adriano, R.; Igarashi, H.
2015-11-01
This paper presents optimal design of an RF energy harvesting device using genetic algorithm (GA). In the present RF harvester, a planar spiral antenna (PSA) is loaded with matching and rectifying circuits. On the first stage of the optimal design, the shape parameters of PSA are optimized using . Then, the equivalent circuit of the optimized PSA is derived for optimization of the circuits. Finally, the parameters of RF energy harvesting circuit are optimized to maximize the output power using GA. It is shown that the present optimization increases the output power by a factor of five. The manufactured energy harvester starts working when the input electric field is greater than 0.5 V/m.
Computational Tools and Algorithms for Designing Customized Synthetic Genes
Gould, Nathan; Hendy, Oliver; Papamichail, Dimitris
2014-01-01
Advances in DNA synthesis have enabled the construction of artificial genes, gene circuits, and genomes of bacterial scale. Freedom in de novo design of synthetic constructs provides significant power in studying the impact of mutations in sequence features, and verifying hypotheses on the functional information that is encoded in nucleic and amino acids. To aid this goal, a large number of software tools of variable sophistication have been implemented, enabling the design of synthetic genes for sequence optimization based on rationally defined properties. The first generation of tools dealt predominantly with singular objectives such as codon usage optimization and unique restriction site incorporation. Recent years have seen the emergence of sequence design tools that aim to evolve sequences toward combinations of objectives. The design of optimal protein-coding sequences adhering to multiple objectives is computationally hard, and most tools rely on heuristics to sample the vast sequence design space. In this review, we study some of the algorithmic issues behind gene optimization and the approaches that different tools have adopted to redesign genes and optimize desired coding features. We utilize test cases to demonstrate the efficiency of each approach, as well as identify their strengths and limitations. PMID:25340050
Computational tools and algorithms for designing customized synthetic genes.
Gould, Nathan; Hendy, Oliver; Papamichail, Dimitris
2014-01-01
Advances in DNA synthesis have enabled the construction of artificial genes, gene circuits, and genomes of bacterial scale. Freedom in de novo design of synthetic constructs provides significant power in studying the impact of mutations in sequence features, and verifying hypotheses on the functional information that is encoded in nucleic and amino acids. To aid this goal, a large number of software tools of variable sophistication have been implemented, enabling the design of synthetic genes for sequence optimization based on rationally defined properties. The first generation of tools dealt predominantly with singular objectives such as codon usage optimization and unique restriction site incorporation. Recent years have seen the emergence of sequence design tools that aim to evolve sequences toward combinations of objectives. The design of optimal protein-coding sequences adhering to multiple objectives is computationally hard, and most tools rely on heuristics to sample the vast sequence design space. In this review, we study some of the algorithmic issues behind gene optimization and the approaches that different tools have adopted to redesign genes and optimize desired coding features. We utilize test cases to demonstrate the efficiency of each approach, as well as identify their strengths and limitations. PMID:25340050
A Parallel Genetic Algorithm for Automated Electronic Circuit Design
NASA Technical Reports Server (NTRS)
Long, Jason D.; Colombano, Silvano P.; Haith, Gary L.; Stassinopoulos, Dimitris
2000-01-01
Parallelized versions of genetic algorithms (GAs) are popular primarily for three reasons: the GA is an inherently parallel algorithm, typical GA applications are very compute intensive, and powerful computing platforms, especially Beowulf-style computing clusters, are becoming more affordable and easier to implement. In addition, the low communication bandwidth required allows the use of inexpensive networking hardware such as standard office ethernet. In this paper we describe a parallel GA and its use in automated high-level circuit design. Genetic algorithms are a type of trial-and-error search technique that are guided by principles of Darwinian evolution. Just as the genetic material of two living organisms can intermix to produce offspring that are better adapted to their environment, GAs expose genetic material, frequently strings of 1s and Os, to the forces of artificial evolution: selection, mutation, recombination, etc. GAs start with a pool of randomly-generated candidate solutions which are then tested and scored with respect to their utility. Solutions are then bred by probabilistically selecting high quality parents and recombining their genetic representations to produce offspring solutions. Offspring are typically subjected to a small amount of random mutation. After a pool of offspring is produced, this process iterates until a satisfactory solution is found or an iteration limit is reached. Genetic algorithms have been applied to a wide variety of problems in many fields, including chemistry, biology, and many engineering disciplines. There are many styles of parallelism used in implementing parallel GAs. One such method is called the master-slave or processor farm approach. In this technique, slave nodes are used solely to compute fitness evaluations (the most time consuming part). The master processor collects fitness scores from the nodes and performs the genetic operators (selection, reproduction, variation, etc.). Because of dependency
Mechanical design of the Mars Pathfinder mission
NASA Technical Reports Server (NTRS)
Eisen, Howard Jay; Buck, Carl W.; Gillis-Smith, Greg R.; Umland, Jeffrey W.
1997-01-01
The Mars Pathfinder mission and the Sojourner rover is reported on, with emphasis on the various mission steps and the performance of the technologies involved. The mechanical design of mission hardware was critical to the success of the entry sequence and the landing operations. The various mechanisms employed are considered.
Mechanical design aspects of the HYVAX railgun
NASA Astrophysics Data System (ADS)
Fox, W. E.; Cummings, C. E.; Davidson, R. F.; Parker, J. V.
1984-03-01
The hypervelocity experiment (HYVAX) railgun is to produce projectile velocities greater than 15 km/s in a 13-m-long, round bore gun. The HYVAX railgun represents a sophisticated, state-of-the-art electromagnetic launcher (EML), which should provide significant information on the performance of these devices. The railgun consists of two kidney-shaped rails adjoining two insulators. Critical mechanical design considerations are related to the minimization of plasma penetration between the rails and insulators to prevent shorting, the minimization of bore deformation under magnetic loading, and the minimization of component stresses at expected loads. Attention is given to design criteria, mechanical design problems, and assembly and alignment.
Geometric methods for the design of mechanisms
NASA Astrophysics Data System (ADS)
Stokes, Ann Westagard
1993-01-01
Challenges posed by the process of designing robotic mechanisms have provided a new impetus to research in the classical subjects of kinematics, elastic analysis, and multibody dynamics. Historically, mechanism designers have considered these areas of analysis to be generally separate and distinct sciences. However, there are significant classes of problems which require a combination of these methods to arrive at a satisfactory solution. For example, both the compliance and the inertia distribution strongly influence the performance of a robotic manipulator. In this thesis, geometric methods are applied to the analysis of mechanisms where kinematics, elasticity, and dynamics play fundamental and interactive roles. Tools for the mathematical analysis, design, and optimization of a class of holonomic and nonholonomic mechanisms are developed. Specific contributions of this thesis include a network theory for elasto-kinematic systems. The applicability of the network theory is demonstrated by employing it to calculate the optimal distribution of joint compliance in a serial manipulator. In addition, the advantage of applying Lie group theoretic approaches to mechanisms requiring specific dynamic properties is demonstrated by extending Brockett's product of exponentials formula to the domain of dynamics. Conditions for the design of manipulators having inertia matrices which are constant in joint angle coordinates are developed. Finally, analysis and design techniques are developed for a class of mechanisms which rectify oscillations into secular motions. These techniques are applied to the analysis of free-floating chains that can reorient themselves in zero angular momentum processes and to the analysis of rattleback tops.
Mechanism design of continuous infrared lens
NASA Astrophysics Data System (ADS)
Su, Yan-qin; Zhang, Jing-xu; Lv, Tian-yu; Yang, Fei; Wang, Fu-guo
2013-09-01
With the development of infrared technology and material, infrared zoom system is playing an important role in the field of photoelectric observation, the demand of infrared systems is increasing rapidly. In order to satisfy the requirement of infrared tracking imaging requirements of a car optoelectronic devices, different kinds of mechanical structure has been discussed, finally, according to the character of the optical design result, cam mechanism is adopted in zoom mechanism design, ball screw has been used in focusing mechanism design. As is known to all, cam is the key part in zoom system, the static, dynamic and thermal characteristics of the cam make great effect on the system performance because of the greater impact of the car's shaking and a larger range of temperature changes, as a result, the FEM analysis is necessary. The static performance is all right obtained by the finite element analysis results, the cam's first -order natural frequency is 97.56 Hz by modal analysis, the deformation of cam in the temperature difference of 80 °C is no more than 0. 003 mm by thermal analysis, which means the mechanical performance of the cam is fine. at last, the focusing mechanism has been designed, and analysis of focusing mechanism precision and encoder theoretical resolving power has been done, this mechanism has the advantages of simple transmission chain and low friction, as well as reducing the transmission error, an absolute encoder is chosen to detect the displacement of the focusing mechanism, the focusing precision is 5μm, the encoder theoretical resolving power is 0.015μm. In addition, the measurements on how to suppress stray radiation have been put forward. The experiment afterward showed that the infrared zoom system performs well, which provides lot of experience in infrared zoom system design and adjustment.
Plant Stems: Functional Design and Mechanics
NASA Astrophysics Data System (ADS)
Speck, Thomas; Burgert, Ingo
2011-08-01
Plant stems are one of nature's most impressive mechanical constructs. Their sophisticated hierarchical structure and multifunctionality allow trees to grow more than 100 m tall. This review highlights the advanced mechanical design of plant stems from the integral level of stem structures down to the fiber-reinforced-composite character of the cell walls. Thereby we intend not only to provide insight into structure-function relationships at the individual levels of hierarchy but to further discuss how growth forms and habits of plant stems are closely interrelated with the peculiarities of their tissue and cell structure and mechanics. This concept is extended to a further key feature of plants, namely, adaptive growth as a reaction to mechanical perturbation and/or changing environmental conditions. These mechanical design principles of plant stems can serve as concept generators for advanced biomimetic materials and may inspire materials and engineering sciences research.
Performance Trend of Different Algorithms for Structural Design Optimization
NASA Technical Reports Server (NTRS)
Patnaik, Surya N.; Coroneos, Rula M.; Guptill, James D.; Hopkins, Dale A.
1996-01-01
Nonlinear programming algorithms play an important role in structural design optimization. Fortunately, several algorithms with computer codes are available. At NASA Lewis Research Center, a project was initiated to assess performance of different optimizers through the development of a computer code CometBoards. This paper summarizes the conclusions of that research. CometBoards was employed to solve sets of small, medium and large structural problems, using different optimizers on a Cray-YMP8E/8128 computer. The reliability and efficiency of the optimizers were determined from the performance of these problems. For small problems, the performance of most of the optimizers could be considered adequate. For large problems however, three optimizers (two sequential quadratic programming routines, DNCONG of IMSL and SQP of IDESIGN, along with the sequential unconstrained minimizations technique SUMT) outperformed others. At optimum, most optimizers captured an identical number of active displacement and frequency constraints but the number of active stress constraints differed among the optimizers. This discrepancy can be attributed to singularity conditions in the optimization and the alleviation of this discrepancy can improve the efficiency of optimizers.
Algorithm design for a gun simulator based on image processing
NASA Astrophysics Data System (ADS)
Liu, Yu; Wei, Ping; Ke, Jun
2015-08-01
In this paper, an algorithm is designed for shooting games under strong background light. Six LEDs are uniformly distributed on the edge of a game machine screen. They are located at the four corners and in the middle of the top and the bottom edges. Three LEDs are enlightened in the odd frames, and the other three are enlightened in the even frames. A simulator is furnished with one camera, which is used to obtain the image of the LEDs by applying inter-frame difference between the even and odd frames. In the resulting images, six LED are six bright spots. To obtain the LEDs' coordinates rapidly, we proposed a method based on the area of the bright spots. After calibrating the camera based on a pinhole model, four equations can be found using the relationship between the image coordinate system and the world coordinate system with perspective transformation. The center point of the image of LEDs is supposed to be at the virtual shooting point. The perspective transformation matrix is applied to the coordinate of the center point. Then we can obtain the virtual shooting point's coordinate in the world coordinate system. When a game player shoots a target about two meters away, using the method discussed in this paper, the calculated coordinate error is less than ten mm. We can obtain 65 coordinate results per second, which meets the requirement of a real-time system. It proves the algorithm is reliable and effective.
Comparative Evaluation of Different Optimization Algorithms for Structural Design Applications
NASA Technical Reports Server (NTRS)
Patnaik, Surya N.; Coroneos, Rula M.; Guptill, James D.; Hopkins, Dale A.
1996-01-01
Non-linear programming algorithms play an important role in structural design optimization. Fortunately, several algorithms with computer codes are available. At NASA Lewis Research Centre, a project was initiated to assess the performance of eight different optimizers through the development of a computer code CometBoards. This paper summarizes the conclusions of that research. CometBoards was employed to solve sets of small, medium and large structural problems, using the eight different optimizers on a Cray-YMP8E/8128 computer. The reliability and efficiency of the optimizers were determined from the performance of these problems. For small problems, the performance of most of the optimizers could be considered adequate. For large problems, however, three optimizers (two sequential quadratic programming routines, DNCONG of IMSL and SQP of IDESIGN, along with Sequential Unconstrained Minimizations Technique SUMT) outperformed others. At optimum, most optimizers captured an identical number of active displacement and frequency constraints but the number of active stress constraints differed among the optimizers. This discrepancy can be attributed to singularity conditions in the optimization and the alleviation of this discrepancy can improve the efficiency of optimizers.
Controller design based on μ analysis and PSO algorithm.
Lari, Ali; Khosravi, Alireza; Rajabi, Farshad
2014-03-01
In this paper an evolutionary algorithm is employed to address the controller design problem based on μ analysis. Conventional solutions to μ synthesis problem such as D-K iteration method often lead to high order, impractical controllers. In the proposed approach, a constrained optimization problem based on μ analysis is defined and then an evolutionary approach is employed to solve the optimization problem. The goal is to achieve a more practical controller with lower order. A benchmark system named two-tank system is considered to evaluate performance of the proposed approach. Simulation results show that the proposed controller performs more effective than high order H(∞) controller and has close responses to the high order D-K iteration controller as the common solution to μ synthesis problem. PMID:24314832
Performance-based seismic design of steel frames utilizing colliding bodies algorithm.
Veladi, H
2014-01-01
A pushover analysis method based on semirigid connection concept is developed and the colliding bodies optimization algorithm is employed to find optimum seismic design of frame structures. Two numerical examples from the literature are studied. The results of the new algorithm are compared to the conventional design methods to show the power or weakness of the algorithm. PMID:25202717
Performance-Based Seismic Design of Steel Frames Utilizing Colliding Bodies Algorithm
Veladi, H.
2014-01-01
A pushover analysis method based on semirigid connection concept is developed and the colliding bodies optimization algorithm is employed to find optimum seismic design of frame structures. Two numerical examples from the literature are studied. The results of the new algorithm are compared to the conventional design methods to show the power or weakness of the algorithm. PMID:25202717
NASA Astrophysics Data System (ADS)
Singh, R.; Verma, H. K.
2013-12-01
This paper presents a teaching-learning-based optimization (TLBO) algorithm to solve parameter identification problems in the designing of digital infinite impulse response (IIR) filter. TLBO based filter modelling is applied to calculate the parameters of unknown plant in simulations. Unlike other heuristic search algorithms, TLBO algorithm is an algorithm-specific parameter-less algorithm. In this paper big bang-big crunch (BB-BC) optimization and PSO algorithms are also applied to filter design for comparison. Unknown filter parameters are considered as a vector to be optimized by these algorithms. MATLAB programming is used for implementation of proposed algorithms. Experimental results show that the TLBO is more accurate to estimate the filter parameters than the BB-BC optimization algorithm and has faster convergence rate when compared to PSO algorithm. TLBO is used where accuracy is more essential than the convergence speed.
The design of aerial camera focusing mechanism
NASA Astrophysics Data System (ADS)
Hu, Changchang; Yang, Hongtao; Niu, Haijun
2015-10-01
In order to ensure the imaging resolution of aerial camera and compensating defocusing caused by the changing of atmospheric temperature, pressure, oblique photographing distance and other environmental factor [1,2], and to meeting the overall design requirements of the camera for the lower mass and smaller size , the linear focusing mechanism is designed. Through the target surface support, the target surface component is connected with focusing driving mechanism. Make use of precision ball screws, focusing mechanism transforms the input rotary motion of motor into linear motion of the focal plane assembly. Then combined with the form of linear guide restraint movement, the magnetic encoder is adopted to detect the response of displacement. And the closed loop control is adopted to realize accurate focusing. This paper illustrated the design scheme for a focusing mechanism and analyzed its error sources. It has the advantages of light friction and simple transmission chain and reducing the transmission error effectively. And this paper also analyses the target surface by finite element analysis and lightweight design. Proving that the precision of focusing mechanism can achieve higher than 3um, and the focusing range is +/-2mm.
Microfluidic serpentine antennas with designed mechanical tunability.
Huang, YongAn; Wang, Yezhou; Xiao, Lin; Liu, Huimin; Dong, Wentao; Yin, Zhouping
2014-11-01
This paper describes the design and characterization of microfluidic serpentine antennas with reversible stretchability and designed mechanical frequency modulation (FM). The microfluidic antennas are designed based on the Poisson's ratio of the elastomer in which the liquid alloy antenna is embedded, to controllably decrease, stabilize or increase its resonance frequency when being stretched. Finite element modelling was used in combination with experimental verification to investigate the effects of substrate dimensions and antenna aspect ratios on the FM sensitivity to uniaxial stretching. It could be designed within the range of -1.2 to 0.6 GHz per 100% stretch. When the aspect ratio of the serpentine antenna is between 1.0 and 1.5, the resonance frequency is stable under stretching, bending, and twisting. The presented microfluidic serpentine antenna design could be utilized in the field of wireless mobile communication for the design of wearable electronics, with a stable resonance frequency under dynamic applied strain up to 50%. PMID:25144304
Mars rover mechanisms designed for Rocky 4
NASA Technical Reports Server (NTRS)
Rivellini, Tommaso P.
1993-01-01
A Mars rover prototype vehicle named Rocky 4 was designed and built at JPL during the fall of 1991 and spring 1992. This vehicle is the fourth in a series of rovers designed to test vehicle mobility and navigation software. Rocky 4 was the first attempt to design a vehicle with 'flight like' mass and functionality. It was consequently necessary to develop highly efficient mechanisms and structures to meet the vehicles very tight mass limit of 3 Kg for the entire mobility system (7 Kg for the full system). This paper will discuss the key mechanisms developed for the rover's innovative drive and suspension system. These are the wheel drive and strut assembly, the rocker-bogie suspension mechanism and the differential pivot. The end-to-end design, analysis, fabrication and testing of these components will also be discussed as will their performance during field testing. The lessons learned from Rocky 4 are already proving invaluable for the design of Rocky 6. Rocky 6 is currently being designed to fly on NASA's MESUR mission to Mars scheduled to launch in 1996.
Design of infrasound-detection system via adaptive LMSTDE algorithm
NASA Technical Reports Server (NTRS)
Khalaf, C. S.; Stoughton, J. W.
1984-01-01
A proposed solution to an aviation safety problem is based on passive detection of turbulent weather phenomena through their infrasonic emission. This thesis describes a system design that is adequate for detection and bearing evaluation of infrasounds. An array of four sensors, with the appropriate hardware, is used for the detection part. Bearing evaluation is based on estimates of time delays between sensor outputs. The generalized cross correlation (GCC), as the conventional time-delay estimation (TDE) method, is first reviewed. An adaptive TDE approach, using the least mean square (LMS) algorithm, is then discussed. A comparison between the two techniques is made and the advantages of the adaptive approach are listed. The behavior of the GCC, as a Roth processor, is examined for the anticipated signals. It is shown that the Roth processor has the desired effect of sharpening the peak of the correlation function. It is also shown that the LMSTDE technique is an equivalent implementation of the Roth processor in the time domain. A LMSTDE lead-lag model, with a variable stability coefficient and a convergence criterion, is designed.
Optimal Robust Motion Controller Design Using Multiobjective Genetic Algorithm
Svečko, Rajko
2014-01-01
This paper describes the use of a multiobjective genetic algorithm for robust motion controller design. Motion controller structure is based on a disturbance observer in an RIC framework. The RIC approach is presented in the form with internal and external feedback loops, in which an internal disturbance rejection controller and an external performance controller must be synthesised. This paper involves novel objectives for robustness and performance assessments for such an approach. Objective functions for the robustness property of RIC are based on simple even polynomials with nonnegativity conditions. Regional pole placement method is presented with the aims of controllers' structures simplification and their additional arbitrary selection. Regional pole placement involves arbitrary selection of central polynomials for both loops, with additional admissible region of the optimized pole location. Polynomial deviation between selected and optimized polynomials is measured with derived performance objective functions. A multiobjective function is composed of different unrelated criteria such as robust stability, controllers' stability, and time-performance indexes of closed loops. The design of controllers and multiobjective optimization procedure involve a set of the objectives, which are optimized simultaneously with a genetic algorithm—differential evolution. PMID:24987749
A homogeneous superconducting magnet design using a hybrid optimization algorithm
NASA Astrophysics Data System (ADS)
Ni, Zhipeng; Wang, Qiuliang; Liu, Feng; Yan, Luguang
2013-12-01
This paper employs a hybrid optimization algorithm with a combination of linear programming (LP) and nonlinear programming (NLP) to design the highly homogeneous superconducting magnets for magnetic resonance imaging (MRI). The whole work is divided into two stages. The first LP stage provides a global optimal current map with several non-zero current clusters, and the mathematical model for the LP was updated by taking into account the maximum axial and radial magnetic field strength limitations. In the second NLP stage, the non-zero current clusters were discretized into practical solenoids. The superconducting conductor consumption was set as the objective function both in the LP and NLP stages to minimize the construction cost. In addition, the peak-peak homogeneity over the volume of imaging (VOI), the scope of 5 Gauss fringe field, and maximum magnetic field strength within superconducting coils were set as constraints. The detailed design process for a dedicated 3.0 T animal MRI scanner was presented. The homogeneous magnet produces a magnetic field quality of 6.0 ppm peak-peak homogeneity over a 16 cm by 18 cm elliptical VOI, and the 5 Gauss fringe field was limited within a 1.5 m by 2.0 m elliptical region.
Orbit design and estimation for surveillance missions using genetic algorithms
NASA Astrophysics Data System (ADS)
Abdelkhalik, Osama Mohamed Omar
2005-11-01
The problem of observing a given set of Earth target sites within an assigned time frame is examined. Attention is given mainly to visiting these sites as sub-satellite nadir points. Solutions to this problem in the literature require thrusters to continuously maneuver the satellite from one site to another. A natural solution is proposed. A natural solution is a gravitational orbit that enables the spacecraft to satisfy the mission requirements without maneuvering. Optimization of a penalty function is performed to find natural solutions for satellite orbit configurations. This penalty function depends on the mission objectives. Two mission objectives are considered: maximum observation time and maximum resolution. The penalty function poses multi minima and a genetic algorithm technique is used to solve this problem. In the case that there is no one orbit satisfying the mission requirements, a multi-orbit solution is proposed. In a multi-orbit solution, the set of target sites is split into two groups. Then the developed algorithm is used to search for a natural solution for each group. The satellite has to be maneuvered between the two solution orbits. Genetic algorithms are used to find the optimal orbit transfer between the two orbits using impulsive thrusters. A new formulation for solving the orbit maneuver problem using genetic algorithms is developed. The developed formulation searches for a minimum fuel consumption maneuver and guarantees that the satellite will be transferred exactly to the final orbit even if the solution is non-optimal. The results obtained demonstrate the feasibility of finding natural solutions for many case studies. The problem of the design of suitable satellite constellation for Earth observing applications is addressed. Two cases are considered. The first is the remote sensing missions for a particular region with high frequency and small swath width. The second is the interferometry radar Earth observation missions. In satellite
Novel design solutions for fishing reel mechanisms
NASA Astrophysics Data System (ADS)
Lovasz, Erwin-Christian; Modler, Karl-Heinz; Neumann, Rudolf; Gruescu, Corina Mihaela; Perju, Dan; Ciupe, Valentin; Maniu, Inocentiu
2015-07-01
Currently, there are various reels on the market regarding the type of mechanism, which achieves the winding and unwinding of the line. The designers have the purpose of obtaining a linear transmission function, by means of a simple and small-sized mechanism. However, the present solutions are not satisfactory because of large deviations from linearity of the transmission function and complexity of mechanical schema. A novel solution for the reel spool mechanism is proposed. Its kinematic schema and synthesis method are described. The kinematic schema of the chosen mechanism is based on a noncircular gear in series with a scotch-yoke mechanism. The yoke is driven by a stud fixed on the driving noncircular gear. The drawbacks of other models regarding the effects occurring at the ends of the spool are eliminated through achieving an appropriate transmission function of the spool. The linear function approximation with curved end-arches appropriately computed to ensure mathematical continuity is very good. The experimental results on the mechanism model validate the theoretical approach. The developed mechanism solution is recorded under a reel spool mechanism patent.
Design considerations for mechanical face seals
NASA Technical Reports Server (NTRS)
Ludwig, L. P.; Greiner, H. F.
1980-01-01
Two companion reports deal with design considerations for improving performance of mechanical face seals, one of family of devices used in general area of fluid sealing of rotating shafts. One report deals with basic seal configuration and other with lubrication of seal.
Combinatorial design of textured mechanical metamaterials.
Coulais, Corentin; Teomy, Eial; de Reus, Koen; Shokef, Yair; van Hecke, Martin
2016-07-28
The structural complexity of metamaterials is limitless, but, in practice, most designs comprise periodic architectures that lead to materials with spatially homogeneous features. More advanced applications in soft robotics, prosthetics and wearable technology involve spatially textured mechanical functionality, which requires aperiodic architectures. However, a naive implementation of such structural complexity invariably leads to geometrical frustration (whereby local constraints cannot be satisfied everywhere), which prevents coherent operation and impedes functionality. Here we introduce a combinatorial strategy for the design of aperiodic, yet frustration-free, mechanical metamaterials that exhibit spatially textured functionalities. We implement this strategy using cubic building blocks-voxels-that deform anisotropically, a local stacking rule that allows cooperative shape changes by guaranteeing that deformed building blocks fit together as in a three-dimensional jigsaw puzzle, and three-dimensional printing. These aperiodic metamaterials exhibit long-range holographic order, whereby the two-dimensional pixelated surface texture dictates the three-dimensional interior voxel arrangement. They also act as programmable shape-shifters, morphing into spatially complex, but predictable and designable, shapes when uniaxially compressed. Finally, their mechanical response to compression by a textured surface reveals their ability to perform sensing and pattern analysis. Combinatorial design thus opens up a new avenue towards mechanical metamaterials with unusual order and machine-like functionalities. PMID:27466125
Combinatorial design of textured mechanical metamaterials
NASA Astrophysics Data System (ADS)
Coulais, Corentin; Teomy, Eial; de Reus, Koen; Shokef, Yair; van Hecke, Martin
2016-07-01
The structural complexity of metamaterials is limitless, but, in practice, most designs comprise periodic architectures that lead to materials with spatially homogeneous features. More advanced applications in soft robotics, prosthetics and wearable technology involve spatially textured mechanical functionality, which requires aperiodic architectures. However, a naive implementation of such structural complexity invariably leads to geometrical frustration (whereby local constraints cannot be satisfied everywhere), which prevents coherent operation and impedes functionality. Here we introduce a combinatorial strategy for the design of aperiodic, yet frustration-free, mechanical metamaterials that exhibit spatially textured functionalities. We implement this strategy using cubic building blocks—voxels—that deform anisotropically, a local stacking rule that allows cooperative shape changes by guaranteeing that deformed building blocks fit together as in a three-dimensional jigsaw puzzle, and three-dimensional printing. These aperiodic metamaterials exhibit long-range holographic order, whereby the two-dimensional pixelated surface texture dictates the three-dimensional interior voxel arrangement. They also act as programmable shape-shifters, morphing into spatially complex, but predictable and designable, shapes when uniaxially compressed. Finally, their mechanical response to compression by a textured surface reveals their ability to perform sensing and pattern analysis. Combinatorial design thus opens up a new avenue towards mechanical metamaterials with unusual order and machine-like functionalities.
Augmented Lagrangian Particle Swarm Optimization in Mechanism Design
NASA Astrophysics Data System (ADS)
Sedlaczek, Kai; Eberhard, Peter
The problem of optimizing nonlinear multibody systems is in general nonlinear and nonconvex. This is especially true for the dimensional synthesis process of rigid body mechanisms, where often only local solutions might be found with gradient-based optimization methods. An attractive alternative for solving such multimodal optimization problems is the Particle Swarm Optimization (PSO) algorithm. This stochastic solution technique allows a derivative-free search for a global solution without the need for any initial design. In this work, we present an extension to the basic PSO algorithm in order to solve the problem of dimensional synthesis with nonlinear equality and inequality constraints. It utilizes the Augmented Lagrange Multiplier Method in combination with an advanced non-stationary penalty function approach that does not rely on excessively large penalty factors for sufficiently accurate solutions. Although the PSO method is even able to solve nonsmooth and discrete problems, this augmented algorithm can additionally calculate accurate Lagrange multiplier estimates for differentiable formulations, which are helpful in the analysis process of the optimization results. We demonstrate this method and show its very promising applicability to the constrained dimensional synthesis process of rigid body mechanisms.
Design definition of a mechanical capacitor
NASA Technical Reports Server (NTRS)
Michaelis, T. D.; Schlieban, E. W.; Scott, R. D.
1977-01-01
A design study and analyses of a 10 kW-hr, 15 kW mechanical capacitor system was studied. It was determined that magnetically supported wheels constructed of advanced composites have the potential for high energy density and high power density. Structural concepts are analyzed that yield the highest energy density of any structural design yet reported. Particular attention was paid to the problem of 'friction' caused by magnetic and I to the second power R losses in the suspension and motor-generator subsystems, and low design friction levels have been achieved. The potentially long shelf life of this system, and the absence of wearing parts, provide superior performance over conventional flywheels supported with mechanical bearings. Costs and economies of energy storage wheels were reviewed briefly.
Designing a Micro-Mechanical Transistor
Mainieri, R.
1999-06-03
This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Micro-mechanical electronic systems are chips with moving parts. They are fabricated with the same techniques that are used to manufacture electronic chips, sharing their low cost. Micro-mechanical chips can also contain electronic components. By combining mechanical parts with electronic parts it becomes possible to process signal mechanically. To achieve designs comparable to those obtained with electronic components it is necessary to have a mechanical device that can change its behavior in response to a small input - a mechanical transistor. The work proposed will develop the design tools for these complex-shaped resonant structures using the geometrical ray technique. To overcome the limitations of geometrical ray chaos, the dynamics of the rays will be studied using the methods developed for the study of nonlinear dynamical systems. T his leads to numerical methods that execute well in parallel computer architectures, using a limited amount of memory and no inter-process communication.
Lapidoth, Gideon D.; Baran, Dror; Pszolla, Gabriele M.; Norn, Christoffer; Alon, Assaf; Tyka, Michael D.; Fleishman, Sarel J.
2016-01-01
Computational design of protein function has made substantial progress, generating new enzymes, binders, inhibitors, and nanomaterials not previously seen in nature. However, the ability to design new protein backbones for function – essential to exert control over all polypeptide degrees of freedom – remains a critical challenge. Most previous attempts to design new backbones computed the mainchain from scratch. Here, instead, we describe a combinatorial backbone and sequence optimization algorithm called AbDesign, which leverages the large number of sequences and experimentally determined molecular structures of antibodies to construct new antibody models, dock them against target surfaces and optimize their sequence and backbone conformation for high stability and binding affinity. We used the algorithm to produce antibody designs that target the same molecular surfaces as nine natural, high-affinity antibodies; in six the backbone conformation at the core of the antibody binding surface is similar to the natural antibody targets, and in several cases sequence and sidechain conformations recapitulate those seen in the natural antibodies. In the case of an anti-lysozyme antibody, designed antibody CDRs at the periphery of the interface, such as L1 and H2, show a greater backbone conformation diversity than the CDRs at the core of the interface, and increase the binding surface area compared to the natural antibody, which could enhance affinity and specificity. PMID:25670500
AHTR Mechanical, Structural, And Neutronic Preconceptual Design
Varma, Venugopal Koikal; Holcomb, David Eugene; Peretz, Fred J; Bradley, Eric Craig; Ilas, Dan; Qualls, A L; Zaharia, Nathaniel M
2012-10-01
This report provides an overview of the mechanical, structural, and neutronic aspects of the Advanced High Temperature Reactor (AHTR) design concept. The AHTR is a design concept for a large output Fluoride salt cooled High-temperature Reactor (FHR) that is being developed to enable evaluation of the technology hurdles remaining to be overcome prior to FHRs becoming a commercial reactor class. This report documents the incremental AHTR design maturation performed over the past year and is focused on advancing the design concept to a level of a functional, self-consistent system. The AHTR employs plate type coated particle fuel assemblies with rapid, off-line refueling. Neutronic analysis of the core has confirmed the viability of a 6-month 2-batch cycle with 9 weight-percent enriched uranium fuel. Refueling is intended to be performed automatically under visual guidance using dedicated robotic manipulators. The present design intent is for used fuel to be stored inside of containment for at least 6 months and then transferred to local dry wells for intermediate term, on-site storage. The mechanical and structural concept development effort has included an emphasis on transportation and constructability to minimize construction costs and schedule. The design intent is that all components be factory fabricated into rail transportable modules that are assembled into subsystems at an on-site workshop prior to being lifted into position using a heavy-lift crane in an open-top style construction. While detailed accident identification and response sequence analysis has yet to be performed, the design concept incorporates multiple levels of radioactive material containment including fully passive responses to all identified design basis or non-very-low frequency beyond design basis accidents. Key building design elements include: 1) below grade siting to minimize vulnerability to aircraft impact, 2) multiple natural circulation decay heat rejection chimneys, 3) seismic
Global and Local Optimization Algorithms for Optimal Signal Set Design
Kearsley, Anthony J.
2001-01-01
The problem of choosing an optimal signal set for non-Gaussian detection was reduced to a smooth inequality constrained mini-max nonlinear programming problem by Gockenbach and Kearsley. Here we consider the application of several optimization algorithms, both global and local, to this problem. The most promising results are obtained when special-purpose sequential quadratic programming (SQP) algorithms are embedded into stochastic global algorithms.
NASA Astrophysics Data System (ADS)
Kanagaraj, G.; Ponnambalam, S. G.; Jawahar, N.; Mukund Nilakantan, J.
2014-10-01
This article presents an effective hybrid cuckoo search and genetic algorithm (HCSGA) for solving engineering design optimization problems involving problem-specific constraints and mixed variables such as integer, discrete and continuous variables. The proposed algorithm, HCSGA, is first applied to 13 standard benchmark constrained optimization functions and subsequently used to solve three well-known design problems reported in the literature. The numerical results obtained by HCSGA show competitive performance with respect to recent algorithms for constrained design optimization problems.
NASA Astrophysics Data System (ADS)
Strzałka, Dominik; Grabowski, Franciszek
Tsallis entropy introduced in 1988 is considered to have obtained new possibilities to construct generalized thermodynamical basis for statistical physics expanding classical Boltzmann-Gibbs thermodynamics for nonequilibrium states. During the last two decades this q-generalized theory has been successfully applied to considerable amount of physically interesting complex phenomena. The authors would like to present a new view on the problem of algorithms computational complexity analysis by the example of the possible thermodynamical basis of the sorting process and its dynamical behavior. A classical approach to the analysis of the amount of resources needed for algorithmic computation is based on the assumption that the contact between the algorithm and the input data stream is a simple system, because only the worst-case time complexity is considered to minimize the dependency on specific instances. Meanwhile the article shows that this process can be governed by long-range dependencies with thermodynamical basis expressed by the specific shapes of probability distributions. The classical approach does not allow to describe all properties of processes (especially the dynamical behavior of algorithms) that can appear during the computer algorithmic processing even if one takes into account the average case analysis in computational complexity. The importance of this problem is still neglected especially if one realizes two important things. The first one: nowadays computer systems work also in an interactive mode and for better understanding of its possible behavior one needs a proper thermodynamical basis. The second one: computers from mathematical point of view are Turing machines but in reality they have physical implementations that need energy for processing and the problem of entropy production appears. That is why the thermodynamical analysis of the possible behavior of the simple insertion sort algorithm will be given here.
NASA Astrophysics Data System (ADS)
Tadaki, Kohtaro
2010-12-01
The statistical mechanical interpretation of algorithmic information theory (AIT, for short) was introduced and developed by our former works [K. Tadaki, Local Proceedings of CiE 2008, pp. 425-434, 2008] and [K. Tadaki, Proceedings of LFCS'09, Springer's LNCS, vol. 5407, pp. 422-440, 2009], where we introduced the notion of thermodynamic quantities, such as partition function Z(T), free energy F(T), energy E(T), statistical mechanical entropy S(T), and specific heat C(T), into AIT. We then discovered that, in the interpretation, the temperature T equals to the partial randomness of the values of all these thermodynamic quantities, where the notion of partial randomness is a stronger representation of the compression rate by means of program-size complexity. Furthermore, we showed that this situation holds for the temperature T itself, which is one of the most typical thermodynamic quantities. Namely, we showed that, for each of the thermodynamic quantities Z(T), F(T), E(T), and S(T) above, the computability of its value at temperature T gives a sufficient condition for T (0,1) to satisfy the condition that the partial randomness of T equals to T. In this paper, based on a physical argument on the same level of mathematical strictness as normal statistical mechanics in physics, we develop a total statistical mechanical interpretation of AIT which actualizes a perfect correspondence to normal statistical mechanics. We do this by identifying a microcanonical ensemble in the framework of AIT. As a result, we clarify the statistical mechanical meaning of the thermodynamic quantities of AIT.
Computational Design of Animated Mechanical Characters
NASA Astrophysics Data System (ADS)
Coros, Stelian; Thomaszewski, Bernhard; DRZ Team Team
2014-03-01
A factor key to the appeal of modern CG movies and video-games is that the virtual worlds they portray place no bounds on what can be imagined. Rapid manufacturing devices hold the promise of bringing this type of freedom to our own world, by enabling the fabrication of physical objects whose appearance, deformation behaviors and motions can be precisely specified. In order to unleash the full potential of this technology however, computational design methods that create digital content suitable for fabrication need to be developed. In recent work, we presented a computational design system that allows casual users to create animated mechanical characters. Given an articulated character as input, the user designs the animated character by sketching motion curves indicating how they should move. For each motion curve, our framework creates an optimized mechanism that reproduces it as closely as possible. The resulting mechanisms are attached to the character and then connected to each other using gear trains, which are created in a semi-automated fashion. The mechanical assemblies generated with our system can be driven with a single input driver, such as a hand-operated crank or an electric motor, and they can be fabricated using rapid prototyping devices.
Sampling design for classifying contaminant level using annealing search algorithms
NASA Astrophysics Data System (ADS)
Christakos, George; Killam, Bart R.
1993-12-01
A stochastic method for sampling spatially distributed contaminant level is presented. The purpose of sampling is to partition the contaminated region into zones of high and low pollutant concentration levels. In particular, given an initial set of observations of a contaminant within a site, it is desired to find a set of additional sampling locations in a way that takes into consideration the spatial variability characteristics of the site and optimizes certain objective functions emerging from the physical, regulatory and monetary considerations of the specific site cleanup process. Since the interest is in classifying the domain into zones above and below a pollutant threshold level, a natural criterion is the cost of misclassification. The resulting objective function is the expected value of a spatial loss function associated with sampling. Stochastic expectation involves the joint probability distribution of the pollutant level and its estimate, where the latter is calculated by means of spatial estimation techniques. Actual computation requires the discretization of the contaminated domain. As a consequence, any reasonably sized problem results in combinatorics precluding an exhaustive search. The use of an annealing algorithm, although suboptimal, can find a good set of future sampling locations quickly and efficiently. In order to obtain insight about the parameters and the computational requirements of the method, an example is discussed in detail. The implementation of spatial sampling design in practice will provide the model inputs necessary for waste site remediation, groundwater management, and environmental decision making.
NASA Astrophysics Data System (ADS)
Tancret, F.
2013-06-01
A new alloy design procedure is proposed, combining in a single computational tool several modelling and predictive techniques that have already been used and assessed in the field of materials science and alloy design: a genetic algorithm is used to optimize the alloy composition for target properties and performance on the basis of the prediction of mechanical properties (estimated by Gaussian process regression of data on existing alloys) and of microstructural constitution, stability and processability (evaluated by computational themodynamics). These tools are integrated in a unique Matlab programme. An example is given in the case of the design of a new nickel-base superalloy for future power plant applications (such as the ultra-supercritical (USC) coal-fired plant, or the high-temperature gas-cooled nuclear reactor (HTGCR or HTGR), where the selection criteria include cost, oxidation and creep resistance around 750 °C, long-term stability at service temperature, forgeability, weldability, etc.
Parallel algorithms for placement and routing in VLSI design. Ph.D. Thesis
NASA Technical Reports Server (NTRS)
Brouwer, Randall Jay
1991-01-01
The computational requirements for high quality synthesis, analysis, and verification of very large scale integration (VLSI) designs have rapidly increased with the fast growing complexity of these designs. Research in the past has focused on the development of heuristic algorithms, special purpose hardware accelerators, or parallel algorithms for the numerous design tasks to decrease the time required for solution. Two new parallel algorithms are proposed for two VLSI synthesis tasks, standard cell placement and global routing. The first algorithm, a parallel algorithm for global routing, uses hierarchical techniques to decompose the routing problem into independent routing subproblems that are solved in parallel. Results are then presented which compare the routing quality to the results of other published global routers and which evaluate the speedups attained. The second algorithm, a parallel algorithm for cell placement and global routing, hierarchically integrates a quadrisection placement algorithm, a bisection placement algorithm, and the previous global routing algorithm. Unique partitioning techniques are used to decompose the various stages of the algorithm into independent tasks which can be evaluated in parallel. Finally, results are presented which evaluate the various algorithm alternatives and compare the algorithm performance to other placement programs. Measurements are presented on the parallel speedups available.
Mechanical engineering capstone senior design textbook
NASA Astrophysics Data System (ADS)
Barrett, Rolin Farrar, Jr.
This textbook is intended to bridge the gap between mechanical engineering equations and mechanical engineering design. To that end, real-world examples are used throughout the book. Also, the material is presented in an order that follows the chronological sequence of coursework that must be performed by a student in the typical capstone senior design course in mechanical engineering. In the process of writing this book, the author surveyed the fifty largest engineering schools (as ranked by the American Society of Engineering Education, or ASEE) to determine what engineering instructors are looking for in a textbook. The survey results revealed a clear need for a textbook written expressly for the capstone senior design course as taught throughout the nation. This book is designed to meet that need. This text was written using an organizational method that the author calls the General Topics Format. The format gives the student reader rapid access to the information contained in the text. All manufacturing methods, and some other material presented in this text, have been presented using the General Topics Format. The text uses examples to explain the importance of understanding the environment in which the product will be used and to discuss product abuse. The safety content contained in this text is unique. The Safety chapter teaches engineering ethics and includes a step-by-step guide to resolving ethical conflicts. The chapter includes explanations of rules, recommendations, standards, consensus standards, key safety concepts, and the legal implications of product failure. Key design principles have been listed and explained. The text provides easy-to-follow design steps, helpful for both the student and new engineer. Prototyping is presented as consisting of three phases: organization, building, and refining. A chapter on common manufacturing methods is included for reference.
AHTR Mechanical, Structural, and Neutronic Preconceptual Design
Varma, V.K.; Holcomb, D.E.; Peretz, F.J.; Bradley, E.C.; Ilas, D.; Qualls, A.L.; Zaharia, N.M.
2012-09-15
This report provides an overview of the mechanical, structural, and neutronic aspects of the Advanced High Temperature Reactor (AHTR) design concept. The AHTR is a design concept for a large output Fluoride salt cooled High-temperature Reactor (FHR) that is being developed to enable evaluation of the technology hurdles remaining to be overcome prior to FHRs becoming an option for commercial reactor deployment. This report documents the incremental AHTR design maturation performed over the past year and is focused on advancing the design concept to a level of a functional, self-consistent system. The reactor concept development remains at a preconceptual level of maturity. While the overall appearance of an AHTR design is anticipated to be similar to the current concept, optimized dimensions will differ from those presented here. The AHTR employs plate type coated particle fuel assemblies with rapid, off-line refueling. Neutronic analysis of the core has confirmed the viability of a 6-month two-batch cycle with 9 wt. % enriched uranium fuel. Refueling is intended to be performed automatically under visual guidance using dedicated robotic manipulators. The report includes a preconceptual design of the manipulators, the fuel transfer system, and the used fuel storage system. The present design intent is for used fuel to be stored inside of containment for at least six months and then transferred to local dry wells for intermediate term, on-site storage. The mechanical and structural concept development effort has included an emphasis on transportation and constructability to minimize construction costs and schedule. The design intent is that all components be factory fabricated into rail transportable modules that are assembled into subsystems at an on-site workshop prior to being lifted into position using a heavy-lift crane in an open-top style construction. While detailed accident identification and response sequence analysis has yet to be performed, the design
Mechanical design of SERT 2 thruster system
NASA Technical Reports Server (NTRS)
Zavesky, R. J.; Hurst, E. B.
1972-01-01
The mechanical design of the mercury bombardment thruster that was tested on SERT is described. The report shows how the structural, thermal, electrical, material compatibility, and neutral mercury coating considerations affected the design and integration of the subsystems and components. The SERT 2 spacecraft with two thrusters was launched on February 3, 1970. One thruster operated for 3782 hours and the other for 2011 hours. A high voltage short resulting from buildup of loose eroded material was believed to be the cause of failure.
Designing Stochastic Optimization Algorithms for Real-world Applications
NASA Astrophysics Data System (ADS)
Someya, Hiroshi; Handa, Hisashi; Koakutsu, Seiichi
This article presents a review of recent advances in stochastic optimization algorithms. Novel algorithms achieving highly adaptive and efficient searches, theoretical analyses to deepen our understanding of search behavior, successful implementation on parallel computers, attempts to build benchmark suites for industrial use, and techniques applied to real-world problems are included. A list of resources is provided.
Hybrid Algorithms for Fuzzy Reverse Supply Chain Network Design
Che, Z. H.; Chiang, Tzu-An; Kuo, Y. C.
2014-01-01
In consideration of capacity constraints, fuzzy defect ratio, and fuzzy transport loss ratio, this paper attempted to establish an optimized decision model for production planning and distribution of a multiphase, multiproduct reverse supply chain, which addresses defects returned to original manufacturers, and in addition, develops hybrid algorithms such as Particle Swarm Optimization-Genetic Algorithm (PSO-GA), Genetic Algorithm-Simulated Annealing (GA-SA), and Particle Swarm Optimization-Simulated Annealing (PSO-SA) for solving the optimized model. During a case study of a multi-phase, multi-product reverse supply chain network, this paper explained the suitability of the optimized decision model and the applicability of the algorithms. Finally, the hybrid algorithms showed excellent solving capability when compared with original GA and PSO methods. PMID:24892057
Opto-mechanical design of PANIC
NASA Astrophysics Data System (ADS)
Fried, Josef W.; Baumeister, Harald; Huber, Armin; Laun, Werner; Rohloff, Ralf-Rainer; Concepción Cárdenas, M.
2010-07-01
PANIC, the Panoramic Near-Infrared Camera, is a new instrument for the Calar Alto Observatory. A 4x4 k detector yields a field of view of 0.5x0.5 degrees at a pixel scale of 0.45 arc sec/pixel at the 2.2m telescope. PANIC can be used also at the 3.5m telescope with half the pixel scale. The optics consists of 9 lenses and 3 folding mirrors. Mechanical tolerances are as small as 50 microns for some elements. PANIC will have a low thermal background due to cold stops. Read-out is done with MPIA's own new electronics which allows read-out of 132 channels in parallel. Weight and size limits lead to interesting design features. Here we describe the opto-mechanical design.
Degradation mechanisms and accelerated aging test design
Clough, R L; Gillen, K T
1985-01-01
The fundamental mechanisms underlying the chemical degradation of polymers can change as a function of environmental stress level. When this occurs, it greatly complicates any attempt to use accelerated tests for predicting long-term material degradation behaviors. Understanding how degradation mechanisms can change at different stress levels facilitates both the design and the interpretation of aging tests. Oxidative degradation is a predominant mechanism for many polymers exposed to a variety of different environments in the presence of air, and there are two mechanistic considerations which are widely applicable to material oxidation. One involves a physical process, oxygen diffusion, as a rate-limiting step. This mechanism can predominate at high stress levels. The second is a chemical process, the time-dependent decomposition of peroxide species. This leads to chain branching and can become a rate-controlling factor at lower stress levels involving time-scales applicable to use environments. The authors describe methods for identifying the operation of these mechanisms and illustrate the dramatic influence they can have on the degradation behaviors of a number of polymer types. Several commonly used approaches to accelerated aging tests are discussed in light of the behaviors which result from changes in degradation mechanisms. 9 references, 4 figures.
Copps, Kevin D.; Carnes, Brian R.
2008-04-01
We examine algorithms for the finite element approximation of thermal contact models. We focus on the implementation of thermal contact algorithms in SIERRA Mechanics. Following the mathematical formulation of models for tied contact and resistance contact, we present three numerical algorithms: (1) the multi-point constraint (MPC) algorithm, (2) a resistance algorithm, and (3) a new generalized algorithm. We compare and contrast both the correctness and performance of the algorithms in three test problems. We tabulate the convergence rates of global norms of the temperature solution on sequentially refined meshes. We present the results of a parameter study of the effect of contact search tolerances. We outline best practices in using the software for predictive simulations, and suggest future improvements to the implementation.
Mechanism Design for Incentivizing Social Media Contributions
NASA Astrophysics Data System (ADS)
Singh, Vivek K.; Jain, Ramesh; Kankanhalli, Mohan
Despite recent advancements in user-driven social media platforms, tools for studying user behavior patterns and motivations remain primitive. We highlight the voluntary nature of user contributions and that users can choose when (and when not) to contribute to the common media pool. A Game theoretic framework is proposed to study the dynamics of social media networks where contribution costs are individual but gains are common. We model users as rational selfish agents, and consider domain attributes like voluntary participation, virtual reward structure, network effect, and public-sharing to model the dynamics of this interaction. The created model describes the most appropriate contribution strategy from each user's perspective and also highlights issues like 'free-rider' problem and individual rationality leading to irrational (i.e. sub-optimal) group behavior. We also consider the perspective of the system designer who is interested in finding the best incentive mechanisms to influence the selfish end-users so that the overall system utility is maximized. We propose and compare multiple mechanisms (based on optimal bonus payment, social incentive leveraging, and second price auction) to study how a system designer can exploit the selfishness of its users, to design incentive mechanisms which improve the overall task-completion probability and system performance, while possibly still benefiting the individual users.
Mechanical Design of Carbon Ion Optics
NASA Technical Reports Server (NTRS)
Haag, Thomas
2005-01-01
Carbon Ion Optics are expected to provide much longer thruster life due to their resistance to sputter erosion. There are a number of different forms of carbon that have been used for fabricating ion thruster optics. The mechanical behavior of carbon is much different than that of most metals, and poses unique design challenges. In order to minimize mission risk, the behavior of carbon must be well understood, and components designed within material limitations. Thermal expansion of the thruster structure must be compatible with thermal expansion of the carbon ion optics. Specially designed interfaces may be needed so that grid gap and aperture alignment are not adversely affected by dissimilar material properties within the thruster. The assembled thruster must be robust and tolerant of launch vibration. The following paper lists some of the characteristics of various carbon materials. Several past ion optics designs are discussed, identifying strengths and weaknesses. Electrostatics and material science are not emphasized so much as the mechanical behavior and integration of grid electrodes into an ion thruster.
The potential of genetic algorithms for conceptual design of rotor systems
NASA Technical Reports Server (NTRS)
Crossley, William A.; Wells, Valana L.; Laananen, David H.
1993-01-01
The capabilities of genetic algorithms as a non-calculus based, global search method make them potentially useful in the conceptual design of rotor systems. Coupling reasonably simple analysis tools to the genetic algorithm was accomplished, and the resulting program was used to generate designs for rotor systems to match requirements similar to those of both an existing helicopter and a proposed helicopter design. This provides a comparison with the existing design and also provides insight into the potential of genetic algorithms in design of new rotors.
Optimal design of low-density SNP arrays for genomic prediction: algorithm and applications
Technology Transfer Automated Retrieval System (TEKTRAN)
Low-density (LD) single nucleotide polymorphism (SNP) arrays provide a cost-effective solution for genomic prediction and selection, but algorithms and computational tools are needed for their optimal design. A multiple-objective, local optimization (MOLO) algorithm was developed for design of optim...
Lansce Wire Scanning Diagnostics Device Mechanical Design
Rodriguez Esparza, Sergio; Batygin, Yuri K.; Gilpatrick, John D.; Gruchalla, Michael E.; Maestas, Alfred J.; Pillai, Chandra; Raybun, Joseph L.; Sattler, F. D.; Sedillo, James Daniel; Smith, Brian G.
2011-01-01
The Accelerator Operations & Technology Division at Los Alamos National Laboratory operates a linear particle accelerator which utilizes 110 wire scanning diagnostics devices to gain position and intensity information of the proton beam. In the upcoming LANSCE improvements, 51 of these wire scanners are to be replaced with a new design, up-to-date technology and off-the-shelf components. This document outlines the requirements for the mechanical design of the LANSCE wire scanner and presents the recently developed linac wire scanner prototype. Additionally, this document presents the design modifications that have been implemented into the fabrication and assembly of this first linac wire scanner prototype. Also, this document will present the design for the second, third, and fourth wire scanner prototypes being developed. Prototypes 2 and 3 belong to a different section of the particle accelerator and therefore have slightly different design specifications. Prototype 4 is a modification of a previously used wire scanner in our facility. Lastly, the paper concludes with a plan for future work on the wire scanner development.
NASA Technical Reports Server (NTRS)
Lawton, Pat
2004-01-01
The objective of this work was to support the design of improved IUE NEWSIPS high dispersion extraction algorithms. The purpose of this work was to evaluate use of the Linearized Image (LIHI) file versus the Re-Sampled Image (SIHI) file, evaluate various extraction, and design algorithms for evaluation of IUE High Dispersion spectra. It was concluded the use of the Re-Sampled Image (SIHI) file was acceptable. Since the Gaussian profile worked well for the core and the Lorentzian profile worked well for the wings, the Voigt profile was chosen for use in the extraction algorithm. It was found that the gamma and sigma parameters varied significantly across the detector, so gamma and sigma masks for the SWP detector were developed. Extraction code was written.
Analysis and optimal design of an underactuated finger mechanism for LARM hand
NASA Astrophysics Data System (ADS)
Yao, Shuangji; Ceccarelli, Marco; Carbone, Giuseppe; Zhan, Qiang; Lu, Zhen
2011-09-01
This paper aims to present general design considerations and optimality criteria for underactuated mechanisms in finger designs. Design issues related to grasping task of robotic fingers are discussed. Performance characteristics are outlined as referring to several aspects of finger mechanisms. Optimality criteria of the finger performances are formulated after careful analysis. A general design algorithm is summarized and formulated as a suitable multi-objective optimization problem. A numerical case of an underactuated robot finger design for Laboratory of Robotics and Mechatronics (LARM) hand is illustrated with the aim to show the practical feasibility of the proposed concepts and computations.
FORTE antenna element and release mechanism design
NASA Technical Reports Server (NTRS)
Rohweller, David J.; Butler, Thomas A.
1995-01-01
The Fast On-Orbit Recording of Transient Events (FORTE) satellite being built by Los Alamos National Laboratory (LANL) and Sandia National Laboratories (SNL) has as its most prominent feature a large deployable (11 m by 5 m) log periodic antenna to monitor emissions from electrical storms on the Earth. This paper describes the antenna and the design for the long elements and explains the dynamics of their deployment and the damping system employed. It also describes the unique paraffin-actuated reusable tie-down and release mechanism employed in the system.
FORTE antenna element and release mechanism design
Rohweller, D.J.; Butler, T.Af.
1995-02-01
The Fast On-Orbit Recording of Transient Events (FORTE) satellite being built by Los Alamos National Laboratory (LANL) and Sandia National Laboratories (SNL) has as its most prominent feature a large deployable (11 m by 5 m) log periodic antenna to monitor emissions from electrical storms on the Earth. This paper describes the antenna and the design for the long elements and explains the dynamics of their deployment and the damping system employed. It also describes the unique paraffin-actuated reusable tie-down and release mechanism employed in the system.
Therapeutic Protein Aggregation: Mechanisms, Design, and Control
Roberts, Christopher J.
2014-01-01
While it is well known that proteins are only marginally stable in their folded states, it is often less well appreciated that most proteins are inherently aggregation-prone in their unfolded or partially unfolded states, and the resulting aggregates can be extremely stable and long-lived. For therapeutic proteins, aggregates are a significant risk factor for deleterious immune responses in patients, and can form via a variety of mechanisms. Controlling aggregation using a mechanistic approach may allow improved design of therapeutic protein stability, as a complement to existing design strategies that target desired protein structures and function. Recent results highlight the importance of balancing protein environment with the inherent aggregation propensities of polypeptide chains. PMID:24908382
Mechanical design of the SNS MEBT
Oshatz, D.; DeMello, A.; Doolittle, L.; Luft, P.; Staples, J.; Zachoszcz, A.
2001-06-11
The Lawrence Berkeley National Laboratory (LBNL) is presently designing and building the 2.5 MeV front end for the Spallation Neutron Source (SNS). The front end includes a medium-energy beam transport (MEBT) that carries the 2.5 MeV, 38 mA peak current, H{sup -} beam from the radio frequency quadrupole (RFQ) to the drift tube linac (DTL) through a series of 14 electromagnetic quadrupoles, four rebuncher cavities, and a fast traveling wave chopping system. The beamline contains numerous diagnostic devices, including stripline beam position and phase monitors (BPM), toroid beam current monitors (BCM), and beam profile monitors. Components are mounted on three rafts that are separately supported and aligned. The large number of beam transport and diagnostic components in the 3.6 meter-long beamline necessitates an unusually compact mechanical design.
Using a Genetic Algorithm to Design Nuclear Electric Spacecraft
NASA Technical Reports Server (NTRS)
Pannell, William P.
2003-01-01
The basic approach to to design nuclear electric spacecraft is to generate a group of candidate designs, see how "fit" the design are, and carry best design forward to the next generation. Some designs eliminated, some randomly modified and carried forward.
Design specification for the whole-body algorithm
NASA Technical Reports Server (NTRS)
Fitzjerrell, D. G.
1974-01-01
The necessary requirements and guidelines for the construction of a computer program of the whole-body algorithm are presented. The minimum subsystem models required to effectively simulate the total body response to stresses of interest are (1) cardiovascular (exercise/LBNP/tilt); (2) respiratory (Grodin's model); (3) thermoregulatory (Stolwijk's model); and (4) long-term circulatory fluid and electrolyte (Guyton's model). The whole-body algorithm must be capable of simulating response to stresses from CO2 inhalation, hypoxia, thermal environmental exercise (sitting and supine), LBNP, and tilt (changing body angles in gravity).
NASA Technical Reports Server (NTRS)
Izumi, K. H.; Thompson, J. L.; Groce, J. L.; Schwab, R. W.
1986-01-01
The design requirements for a 4D path definition algorithm are described. These requirements were developed for the NASA ATOPS as an extension of the Local Flow Management/Profile Descent algorithm. They specify the processing flow, functional and data architectures, and system input requirements, and recommended the addition of a broad path revision (reinitialization) function capability. The document also summarizes algorithm design enhancements and the implementation status of the algorithm on an in-house PDP-11/70 computer. Finally, the requirements for the pilot-computer interfaces, the lateral path processor, and guidance and steering function are described.
NASA Astrophysics Data System (ADS)
Zecchin, A. C.; Simpson, A. R.; Maier, H. R.; Marchi, A.; Nixon, J. B.
2012-09-01
Evolutionary algorithms (EAs) have been applied successfully to many water resource problems, such as system design, management decision formulation, and model calibration. The performance of an EA with respect to a particular problem type is dependent on how effectively its internal operators balance the exploitation/exploration trade-off to iteratively find solutions of an increasing quality. For a given problem, different algorithms are observed to produce a variety of different final performances, but there have been surprisingly few investigations into characterizing how the different internal mechanisms alter the algorithm's searching behavior, in both the objective and decision space, to arrive at this final performance. This paper presents metrics for analyzing the searching behavior of ant colony optimization algorithms, a particular type of EA, for the optimal water distribution system design problem, which is a classical NP-hard problem in civil engineering. Using the proposed metrics, behavior is characterized in terms of three different attributes: (1) the effectiveness of the search in improving its solution quality and entering into optimal or near-optimal regions of the search space, (2) the extent to which the algorithm explores as it converges to solutions, and (3) the searching behavior with respect to the feasible and infeasible regions. A range of case studies is considered, where a number of ant colony optimization variants are applied to a selection of water distribution system optimization problems. The results demonstrate the utility of the proposed metrics to give greater insight into how the internal operators affect each algorithm's searching behavior.
DESIGNING SUSTAINABLE PROCESSES WITH SIMULATION: THE WASTE REDUCTION (WAR) ALGORITHM
The WAR Algorithm, a methodology for determining the potential environmental impact (PEI) of a chemical process, is presented with modifications that account for the PEI of the energy consumed within that process. From this theory, four PEI indexes are used to evaluate the envir...
3D-design exploration of CNN algorithms
NASA Astrophysics Data System (ADS)
Spaanenburg, Lambert; Malki, Suleyman
2011-05-01
Multi-dimensional algorithms are hard to implement on classical platforms. Pipelining may exploit instruction-level parallelism, but not in the presence of simultaneous data; threads optimize only within the given restrictions. Tiled architectures do add a dimension to the solution space. With locally a large register store, data parallelism is handled, but only to a dimension. 3-D technologies are meant to add a dimension in the realization. Applied on the device level, it makes each computational node smaller. The interconnections become shorter and hence the network will be condensed. Such advantages will be easily lost at higher implementation levels unless 3-D technologies as multi-cores or chip stacking are also introduced. 3-D technologies scale in space, where (partial) reconfiguration scales in time. The optimal selection over the various implementation levels is algorithm dependent. The paper discusses such principles while applied on the scaling of cellular neural networks (CNN). It illustrates how stacking of reconfigurable chips supports many algorithmic requirements in a defect-insensitive manner. Further the paper explores the potential of chip stacking for multi-modal implementations in a reconfigurable approach to heterogeneous architectures for algorithm domains.
High pressure humidification columns: Design equations, algorithm, and computer code
Enick, R.M.; Klara, S.M.; Marano, J.J.
1994-07-01
This report describes the detailed development of a computer model to simulate the humidification of an air stream in contact with a water stream in a countercurrent, packed tower, humidification column. The computer model has been developed as a user model for the Advanced System for Process Engineering (ASPEN) simulator. This was done to utilize the powerful ASPEN flash algorithms as well as to provide ease of use when using ASPEN to model systems containing humidification columns. The model can easily be modified for stand-alone use by incorporating any standard algorithm for performing flash calculations. The model was primarily developed to analyze Humid Air Turbine (HAT) power cycles; however, it can be used for any application that involves a humidifier or saturator. The solution is based on a multiple stage model of a packed column which incorporates mass and energy, balances, mass transfer and heat transfer rate expressions, the Lewis relation and a thermodynamic equilibrium model for the air-water system. The inlet air properties, inlet water properties and a measure of the mass transfer and heat transfer which occur in the column are the only required input parameters to the model. Several example problems are provided to illustrate the algorithm`s ability to generate the temperature of the water, flow rate of the water, temperature of the air, flow rate of the air and humidity of the air as a function of height in the column. The algorithm can be used to model any high-pressure air humidification column operating at pressures up to 50 atm. This discussion includes descriptions of various humidification processes, detailed derivations of the relevant expressions, and methods of incorporating these equations into a computer model for a humidification column.
Design and analysis of closed-loop decoder adaptation algorithms for brain-machine interfaces.
Dangi, Siddharth; Orsborn, Amy L; Moorman, Helene G; Carmena, Jose M
2013-07-01
Closed-loop decoder adaptation (CLDA) is an emerging paradigm for achieving rapid performance improvements in online brain-machine interface (BMI) operation. Designing an effective CLDA algorithm requires making multiple important decisions, including choosing the timescale of adaptation, selecting which decoder parameters to adapt, crafting the corresponding update rules, and designing CLDA parameters. These design choices, combined with the specific settings of CLDA parameters, will directly affect the algorithm's ability to make decoder parameters converge to values that optimize performance. In this article, we present a general framework for the design and analysis of CLDA algorithms and support our results with experimental data of two monkeys performing a BMI task. First, we analyze and compare existing CLDA algorithms to highlight the importance of four critical design elements: the adaptation timescale, selective parameter adaptation, smooth decoder updates, and intuitive CLDA parameters. Second, we introduce mathematical convergence analysis using measures such as mean-squared error and KL divergence as a useful paradigm for evaluating the convergence properties of a prototype CLDA algorithm before experimental testing. By applying these measures to an existing CLDA algorithm, we demonstrate that our convergence analysis is an effective analytical tool that can ultimately inform and improve the design of CLDA algorithms. PMID:23607558
Use of Algorithm of Changes for Optimal Design of Heat Exchanger
NASA Astrophysics Data System (ADS)
Tam, S. C.; Tam, H. K.; Chio, C. H.; Tam, L. M.
2010-05-01
For economic reasons, the optimal design of heat exchanger is required. Design of heat exchanger is usually based on the iterative process. The design conditions, equipment geometries, the heat transfer and friction factor correlations are totally involved in the process. Using the traditional iterative method, many trials are needed for satisfying the compromise between the heat exchange performance and the cost consideration. The process is cumbersome and the optimal design is often depending on the design engineer's experience. Therefore, in the recent studies, many researchers, reviewed in [1], applied the genetic algorithm (GA) [2] for designing the heat exchanger. The results outperformed the traditional method. In this study, the alternative approach, algorithm of changes, is proposed for optimal design of shell-tube heat exchanger [3]. This new method, algorithm of changes based on I Ching (???), is developed originality by the author. In the algorithms, the hexagram operations in I Ching has been generalized to binary string case and the iterative procedure which imitates the I Ching inference is also defined. On the basis of [3], the shell inside diameter, tube outside diameter, and baffles spacing were treated as the design (or optimized) variables. The cost of the heat exchanger was arranged as the objective function. Through the case study, the results show that the algorithm of changes is comparable to the GA method. Both of method can find the optimal solution in a short time. However, without interchanging information between binary strings, the algorithm of changes has advantage on parallel computation over GA.
Mechanical cloak design by direct lattice transformation.
Bückmann, Tiemo; Kadic, Muamer; Schittny, Robert; Wegener, Martin
2015-04-21
Spatial coordinate transformations have helped simplifying mathematical issues and solving complex boundary-value problems in physics for decades already. More recently, material-parameter transformations have also become an intuitive and powerful engineering tool for designing inhomogeneous and anisotropic material distributions that perform wanted functions, e.g., invisibility cloaking. A necessary mathematical prerequisite for this approach to work is that the underlying equations are form invariant with respect to general coordinate transformations. Unfortunately, this condition is not fulfilled in elastic-solid mechanics for materials that can be described by ordinary elasticity tensors. Here, we introduce a different and simpler approach. We directly transform the lattice points of a 2D discrete lattice composed of a single constituent material, while keeping the properties of the elements connecting the lattice points the same. After showing that the approach works in various areas, we focus on elastic-solid mechanics. As a demanding example, we cloak a void in an effective elastic material with respect to static uniaxial compression. Corresponding numerical calculations and experiments on polymer structures made by 3D printing are presented. The cloaking quality is quantified by comparing the average relative SD of the strain vectors outside of the cloaked void with respect to the homogeneous reference lattice. Theory and experiment agree and exhibit very good cloaking performance. PMID:25848021
Mechanical cloak design by direct lattice transformation
Bückmann, Tiemo; Kadic, Muamer; Schittny, Robert; Wegener, Martin
2015-01-01
Spatial coordinate transformations have helped simplifying mathematical issues and solving complex boundary-value problems in physics for decades already. More recently, material-parameter transformations have also become an intuitive and powerful engineering tool for designing inhomogeneous and anisotropic material distributions that perform wanted functions, e.g., invisibility cloaking. A necessary mathematical prerequisite for this approach to work is that the underlying equations are form invariant with respect to general coordinate transformations. Unfortunately, this condition is not fulfilled in elastic–solid mechanics for materials that can be described by ordinary elasticity tensors. Here, we introduce a different and simpler approach. We directly transform the lattice points of a 2D discrete lattice composed of a single constituent material, while keeping the properties of the elements connecting the lattice points the same. After showing that the approach works in various areas, we focus on elastic–solid mechanics. As a demanding example, we cloak a void in an effective elastic material with respect to static uniaxial compression. Corresponding numerical calculations and experiments on polymer structures made by 3D printing are presented. The cloaking quality is quantified by comparing the average relative SD of the strain vectors outside of the cloaked void with respect to the homogeneous reference lattice. Theory and experiment agree and exhibit very good cloaking performance. PMID:25848021
LANSCE wire scanning diagnostics device mechanical design
Rodriguez Esparza, Sergio
2010-01-01
The Los Alamos Neutron Science Center (LANSCE) is one of the major experimental science facilities at the Los Alamos National Laboratory (LANL). The core of LANSCE's work lies in the operation of a powerful linear accelerator, which accelerates protons up to 84% the speed oflight. These protons are used for a variety of purposes, including materials testing, weapons research and isotopes production. To assist in guiding the proton beam, a series of over one hundred wire scanners are used to measure the beam profile at various locations along the half-mile length of the particle accelerator. A wire scanner is an electro-mechanical device that moves a set of wires through a particle beam and measures the secondary emissions from the resulting beam-wire interaction to obtain beam intensity information. When supplemented with data from a position sensor, this information is used to determine the cross-sectional profile of the beam. This measurement allows beam operators to adjust parameters such as acceleration, beam steering, and focus to ensure that the beam reaches its destination as effectively as possible. Some of the current wire scanners are nearly forty years old and are becoming obsolete. The problem with current wire scanners comes in the difficulty of maintenance and reliability. The designs of these wire scanners vary making it difficult to keep spare parts that would work on all designs. Also many of the components are custom built or out-dated technology and are no longer in production.
"Basic MR Relaxation Mechanisms & Contrast Agent Design"
De León-Rodríguez, Luis M.; Martins, André F.; Pinho, Marco; Rofsky, Neil; Sherry, A. Dean
2015-01-01
The diagnostic capabilities of magnetic resonance imaging (MRI) have undergone continuous and substantial evolution by virtue of hardware and software innovations and the development and implementation of exogenous contrast media. Thirty years since the first MRI contrast agent was approved for clinical use, a reliance on MR contrast media persists largely to improve image quality with higher contrast resolution and to provide additional functional characterization of normal and abnormal tissues. Further development of MR contrast media is an important component in the quest for continued augmentation of diagnostic capabilities. In this review we will detail the many important considerations when pursuing the design and use of MR contrast media. We will offer a perspective on the importance of chemical stability, particularly kinetic stability, and how this influences one's thinking about the safety of metal-ligand based contrast agents. We will discuss the mechanisms involved in magnetic resonance relaxation in the context of probe design strategies. A brief description of currently available contrast agents will be accompanied by an in-depth discussion that highlights promising MRI contrast agents in development for future clinical and research applications. Our intention is to give a diverse audience an improved understanding of the factors involved in developing new types of safe and highly efficient MR contrast agents and, at the same time, provide an appreciation of the insights into physiology and disease that newer types of responsive agents can provide. PMID:25975847
ERIC Educational Resources Information Center
Tran, Huu-Khoa; Chiou, Juing -Shian; Peng, Shou-Tao
2016-01-01
In this paper, the feasibility of a Genetic Algorithm Optimization (GAO) education software based Fuzzy Logic Controller (GAO-FLC) for simulating the flight motion control of Unmanned Aerial Vehicles (UAVs) is designed. The generated flight trajectories integrate the optimized Scaling Factors (SF) fuzzy controller gains by using GAO algorithm. The…
Hybrid real-code ant colony optimisation for constrained mechanical design
NASA Astrophysics Data System (ADS)
Pholdee, Nantiwat; Bureerat, Sujin
2016-01-01
This paper proposes a hybrid meta-heuristic based on integrating a local search simplex downhill (SDH) method into the search procedure of real-code ant colony optimisation (ACOR). This hybridisation leads to five hybrid algorithms where a Monte Carlo technique, a Latin hypercube sampling technique (LHS) and a translational propagation Latin hypercube design (TPLHD) algorithm are used to generate an initial population. Also, two numerical schemes for selecting an initial simplex are investigated. The original ACOR and its hybrid versions along with a variety of established meta-heuristics are implemented to solve 17 constrained test problems where a fuzzy set theory penalty function technique is used to handle design constraints. The comparative results show that the hybrid algorithms are the top performers. Using the TPLHD technique gives better results than the other sampling techniques. The hybrid optimisers are a powerful design tool for constrained mechanical design problems.
Evaluation of a segmentation algorithm designed for an FPGA implementation
NASA Astrophysics Data System (ADS)
Schwenk, Kurt; Schönermark, Maria; Huber, Felix
2013-10-01
The present work has to be seen in the context of real-time on-board image evaluation of optical satellite data. With on board image evaluation more useful data can be acquired, the time to get requested information can be decreased and new real-time applications are possible. Because of the relative high processing power in comparison to the low power consumption, Field Programmable Gate Array (FPGA) technology has been chosen as an adequate hardware platform for image processing tasks. One fundamental part for image evaluation is image segmentation. It is a basic tool to extract spatial image information which is very important for many applications such as object detection. Therefore a special segmentation algorithm using the advantages of FPGA technology has been developed. The aim of this work is the evaluation of this algorithm. Segmentation evaluation is a difficult task. The most common way for evaluating the performance of a segmentation method is still subjective evaluation, in which human experts determine the quality of a segmentation. This way is not in compliance with our needs. The evaluation process has to provide a reasonable quality assessment, should be objective, easy to interpret and simple to execute. To reach these requirements a so called Segmentation Accuracy Equality norm (SA EQ) was created, which compares the difference of two segmentation results. It can be shown that this norm is capable as a first quality measurement. Due to its objectivity and simplicity the algorithm has been tested on a specially chosen synthetic test model. In this work the most important results of the quality assessment will be presented.
Design of broadband omnidirectional antireflection coatings using ant colony algorithm.
Guo, X; Zhou, H Y; Guo, S; Luan, X X; Cui, W K; Ma, Y F; Shi, L
2014-06-30
Optimization method which is based on the ant colony algorithm (ACA) is described to optimize antireflection (AR) coating system with broadband omnidirectional characteristics for silicon solar cells incorporated with the solar spectrum (AM1.5 radiation). It's the first time to use ACA method for optimizing the AR coating system. In this paper, for the wavelength range from 400 nm to 1100 nm, the optimized three-layer AR coating system could provide an average reflectance of 2.98% for incident angles from Raveθ+ to 80° and 6.56% for incident angles from 0° to 90°. PMID:24978076
An Object-Oriented Collection of Minimum Degree Algorithms: Design, Implementation, and Experiences
NASA Technical Reports Server (NTRS)
Kumfert, Gary; Pothen, Alex
1999-01-01
The multiple minimum degree (MMD) algorithm and its variants have enjoyed 20+ years of research and progress in generating fill-reducing orderings for sparse, symmetric positive definite matrices. Although conceptually simple, efficient implementations of these algorithms are deceptively complex and highly specialized. In this case study, we present an object-oriented library that implements several recent minimum degree-like algorithms. We discuss how object-oriented design forces us to decompose these algorithms in a different manner than earlier codes and demonstrate how this impacts the flexibility and efficiency of our C++ implementation. We compare the performance of our code against other implementations in C or Fortran.
A general theory known as the WAste Reduction (WASR) algorithm has been developed to describe the flow and the generation of potential environmental impact through a chemical process. This theory integrates environmental impact assessment into chemical process design Potential en...
NASA Astrophysics Data System (ADS)
Bigdeli, Kasra; Hare, Warren; Tesfamariam, Solomon
2012-04-01
Passive dampers can be used to connect two adjacent structures in order to mitigate earthquakes induced pounding damages. Theoretical and experimental studies have confirmed efficiency and applicability of various connecting devices, such as viscous damper, MR damper, etc. However, few papers employed optimization methods to find the optimal mechanical properties of the dampers, and in most papers, dampers are assumed to be uniform. In this study, we optimized the optimal damping coefficients of viscous dampers considering a general case of non-uniform damping coefficients. Since the derivatives of objective function to damping coefficients are not known, to optimize damping coefficients, a heuristic search method, i.e. the genetic algorithm, is employed. Each structure is modeled as a multi degree of freedom dynamic system consisting of lumped-masses, linear springs and dampers. In order to examine dynamic behavior of the structures, simulations in frequency domain are carried out. A pseudo-excitation based on Kanai-Tajimi spectrum is used as ground acceleration. The optimization results show that relaxing the uniform dampers coefficient assumption generates significant improvement in coupling effectiveness. To investigate efficiency of genetic algorithm, solution quality and solution time of genetic algorithm are compared with those of Nelder-Mead algorithm.
A hybrid algorithm for transonic airfoil and wing design
NASA Technical Reports Server (NTRS)
Campbell, Richard L.; Smith, Leigh A.
1987-01-01
The present method for the design of transonic airfoils and wings employs a predictor/corrector approach in which an analysis code calculates the flowfield for an initial geometry, then modifies it on the basis of the difference between calculated and target pressures. This allows the design method to be straightforwardly coupled with any existing analysis code, as presently undertaken with several two- and three-dimensional potential flow codes. The results obtained indicate that the method is robust and accurate, even in the cases of airfoils with strongly supercritical flow and shocks. The design codes are noted to require computational resources typical of current pure-inverse methods.
Vision-based vehicle detection and tracking algorithm design
NASA Astrophysics Data System (ADS)
Hwang, Junyeon; Huh, Kunsoo; Lee, Donghwi
2009-12-01
The vision-based vehicle detection in front of an ego-vehicle is regarded as promising for driver assistance as well as for autonomous vehicle guidance. The feasibility of vehicle detection in a passenger car requires accurate and robust sensing performance. A multivehicle detection system based on stereo vision has been developed for better accuracy and robustness. This system utilizes morphological filter, feature detector, template matching, and epipolar constraint techniques in order to detect the corresponding pairs of vehicles. After the initial detection, the system executes the tracking algorithm for the vehicles. The proposed system can detect front vehicles such as the leading vehicle and side-lane vehicles. The position parameters of the vehicles located in front are obtained based on the detection information. The proposed vehicle detection system is implemented on a passenger car, and its performance is verified experimentally.
The design of flux-corrected transport (FCT) algorithms on structured grids
NASA Astrophysics Data System (ADS)
Zalesak, Steven T.
2005-12-01
A given flux-corrected transport (FCT) algorithm consists of three components: (1) a high order algorithm to which it reduces in smooth parts of the flow field; (2) a low order algorithm to which it reduces in parts of the flow devoid of smoothness; and (3) a flux limiter which calculates the weights assigned to the high and low order algorithms, in flux form, in the various regions of the flow field. In this dissertation, we describe a set of design principles that significantly enhance the accuracy and robustness of FCT algorithms by enhancing the accuracy and robustness of each of the three components individually. These principles include the use of very high order spatial operators in the design of the high order fluxes, the use of non-clipping flux limiters, the appropriate choice of constraint variables in the critical flux-limiting step, and the implementation of a "failsafe" flux-limiting strategy. We show via standard test problems the kind of algorithm performance one can expect if these design principles are adhered to. We give examples of applications of these design principles in several areas of physics. Finally, we compare the performance of these enhanced algorithms with that of other recent front-capturing methods.
General Structure Design for Fast Image Processing Algorithms Based upon FPGA DSP Slice
NASA Astrophysics Data System (ADS)
Wasfy, Wael; Zheng, Hong
Increasing the speed and accuracy for a fast image processing algorithms during computing the image intensity for low level 3x3 algorithms with different kernel but having the same parallel calculation method is our target to achieve in this paper. FPGA is one of the fastest embedded systems that can be used for implementing the fast image processing image algorithms by using DSP slice module inside the FPGA we aimed to get the advantage of the DSP slice as a faster, accurate, higher number of bits in calculations and different calculated equation maneuver capabilities. Using a higher number of bits during algorithm calculations will lead to a higher accuracy compared with using the same image algorithm calculations with less number of bits, also reducing FPGA resources as minimum as we can and according to algorithm calculations needs is a very important goal to achieve. So in the recommended design we used as minimum DSP slice as we can and as a benefit of using DSP slice is higher calculations accuracy as the DSP capabilities of having 48 bit accuracy in addition and 18 x 18 bit accuracy in multiplication. For proofing the design, Gaussian filter and Sobelx edge detector image processing algorithms have been chosen to be implemented. Also we made a comparison with another design for proofing the improvements of the accuracy and speed of calculations, the other design as will be mentioned later on this paper is using maximum 12 bit accuracy in adding or multiplying calculations.
Internal circulating fluidized bed incineration system and design algorithm.
Tian, W D; Wei, X L; Li, J; Sheng, H Z
2001-04-01
The internal circulating fluidized bed (ICFB) system is characterized with fast combustion, low emission, uniformity of bed temperature and controllability of combustion process. It is a kind of novel clean combustion system, especially for the low-grade fuels, such as municipal solid waste (MSW). The experimental systems of ICFB with and without combustion were designed and set up in this paper. A series of experiments were carried out for further understanding combustion process and characteristics of several design parameters for MSW. Based on the results, a design routine for the ICFB system was suggested for the calculation of energy balance, airflow rate, heat transfer rate, and geometry arrangement. A test system with ICFB combustor has been set up and the test results show that the design of the ICFB system is successful. PMID:11590739
Designer spin systems via inverse statistical mechanics
NASA Astrophysics Data System (ADS)
DiStasio, Robert A., Jr.; Marcotte, Étienne; Car, Roberto; Stillinger, Frank H.; Torquato, Salvatore
2013-10-01
nature of the target radial spin-spin correlation function. In the future, it will be interesting to explore whether such inverse statistical-mechanical techniques could be employed to design materials with desired spin properties.
Sequence-Specific Copolymer Compatibilizers designed via a Genetic Algorithm
NASA Astrophysics Data System (ADS)
Meenakshisundaram, Venkatesh; Patra, Tarak; Hung, Jui-Hsiang; Simmons, David
For several decades, block copolymers have been employed as surfactants to reduce interfacial energy for applications from emulsification to surface adhesion. While the simplest approach employs symmetric diblocks, studies have examined asymmetric diblocks, multiblock copolymers, gradient copolymers, and copolymer-grafted nanoparticles. However, there exists no established approach to determining the optimal copolymer compatibilizer sequence for a given application. Here we employ molecular dynamics simulations within a genetic algorithm to identify copolymer surfactant sequences yielding maximum reductions the interfacial energy of model immiscible polymers. The optimal copolymer sequence depends significantly on surfactant concentration. Most surprisingly, at high surface concentrations, where the surfactant achieves the greatest interfacial energy reduction, specific non-periodic sequences are found to significantly outperform any regularly blocky sequence. This emergence of polymer sequence-specificity within a non-sequenced environment adds to a recent body of work suggesting that specific sequence may have the potential to play a greater role in polymer properties than previously understood. We acknowledge the W. M. Keck Foundation for financial support of this research.
Preliminary Design of a Manned Nuclear Electric Propulsion Vehicle Using Genetic Algorithms
NASA Astrophysics Data System (ADS)
Irwin, Ryan W.; Tinker, Michael L.
2005-02-01
Nuclear electric propulsion (NEP) vehicles will be needed for future manned missions to Mars and beyond. Candidate designs must be identified for further detailed design from a large array of possibilities. Genetic algorithms have proven their utility in conceptual design studies by effectively searching a large design space to pinpoint unique optimal designs. This research combined analysis codes for NEP subsystems with a genetic algorithm. The use of penalty functions with scaling ratios was investigated to increase computational efficiency. Also, the selection of design variables for optimization was considered to reduce computation time without losing beneficial design search space. Finally, trend analysis of a reference mission to the asteroids yielded a group of candidate designs for further analysis.
Preliminary Design of a Manned Nuclear Electric Propulsion Vehicle Using Genetic Algorithms
Irwin, Ryan W.; Tinker, Michael L.
2005-02-06
Nuclear electric propulsion (NEP) vehicles will be needed for future manned missions to Mars and beyond. Candidate designs must be identified for further detailed design from a large array of possibilities. Genetic algorithms have proven their utility in conceptual design studies by effectively searching a large design space to pinpoint unique optimal designs. This research combined analysis codes for NEP subsystems with a genetic algorithm. The use of penalty functions with scaling ratios was investigated to increase computational efficiency. Also, the selection of design variables for optimization was considered to reduce computation time without losing beneficial design search space. Finally, trend analysis of a reference mission to the asteroids yielded a group of candidate designs for further analysis.
Preliminary Design of a Manned Nuclear Electric Propulsion Vehicle Using Genetic Algorithms
NASA Technical Reports Server (NTRS)
Irwin, Ryan W.; Tinker, Michael L.
2005-01-01
Nuclear electric propulsion (NEP) vehicles will be needed for future manned missions to Mars and beyond. Candidate designs must be identified for further detailed design from a large array of possibilities. Genetic algorithms have proven their utility in conceptual design studies by effectively searching a large design space to pinpoint unique optimal designs. This research combined analysis codes for NEP subsystems with a genetic algorithm. The use of penalty functions with scaling ratios was investigated to increase computational efficiency. Also, the selection of design variables for optimization was considered to reduce computation time without losing beneficial design search space. Finally, trend analysis of a reference mission to the asteroids yielded a group of candidate designs for further analysis.
Overlay measurement accuracy enhancement by design and algorithm
NASA Astrophysics Data System (ADS)
Lee, Honggoo; Lee, Byongseog; Han, Sangjun; Kim, Myoungsoo; Kwon, Wontaik; Park, Sungki; Choi, DongSub; Lee, Dohwa; Jeon, Sanghuck; Lee, Kangsan; Itzkovich, Tal; Amir, Nuriel; Volkovich, Roie; Herzel, Eitan; Wagner, Mark; El Kodadi, Mohamed
2015-03-01
Advanced design nodes require more complex lithography techniques, such as double patterning, as well as advanced materials like hard masks. This poses new challenge for overlay metrology and process control. In this publication several step are taken to face these challenges. Accurate overlay metrology solutions are demonstrated for advanced memory devices.
A sequential implicit algorithm of chemo-thermo-poro-mechanics for fractured geothermal reservoirs
NASA Astrophysics Data System (ADS)
Kim, Jihoon; Sonnenthal, Eric; Rutqvist, Jonny
2015-03-01
We describe the development of a sequential implicit formulation and algorithm for coupling fluid-heat flow, reactive transport, and geomechanics. We consider changes in pore volume from dissolution caused by chemical reactions, in addition to coupled flow and geomechanics. Moreover, we use the constitutive equations for the multiple porosity model for fractured geothermal reservoirs, employing failure-dependent permeability dynamically and updating it every time step. The proposed sequential algorithm is an extension of the fixed-stress split method to chemo-thermo-poro-mechanics, facilitating the use of existing flow-reactive transport and geomechanics simulators. We first validate a simulator that employs the proposed sequential algorithm, matching the numerical solutions with the analytical solutions such as Terzaghi's and Mandel's problems for poro-mechanics and the reference solutions of chemo-poro-mechanics and chemo-thermo-poro-mechanics in the 1D elastic problems. We also perform convergence test, and the proposed algorithm shows fast convergence, when full iteration is taken, and first order accuracy in time for the staggered approach. We then investigate two test cases: 2D multiple porosity elastic and 3D single porosity elastoplastic problems, and explore the differences in coupled flow and geomechanics with and without reactive transport. We find that the change in pore-volume induced by mineral dissolution can impact on fluid pressure and failure status, followed by significant changes in permeability and flow variables, showing strong interrelations between flow-reactive transport and geomechanics.
On Polymorphic Circuits and Their Design Using Evolutionary Algorithms
NASA Technical Reports Server (NTRS)
Stoica, Adrian; Zebulum, Ricardo; Keymeulen, Didier; Lohn, Jason; Clancy, Daniel (Technical Monitor)
2002-01-01
This paper introduces the concept of polymorphic electronics (polytronics) - referring to electronics with superimposed built-in functionality. A function change does not require switches/reconfiguration as in traditional approaches. Instead the change comes from modifications in the characteristics of devices involved in the circuit, in response to controls such as temperature, power supply voltage (VDD), control signals, light, etc. The paper illustrates polytronic circuits in which the control is done by temperature, morphing signals, and VDD respectively. Polytronic circuits are obtained by evolutionary design/evolvable hardware techniques. These techniques are ideal for the polytronics design, a new area that lacks design guidelines, know-how,- yet the requirements/objectives are easy to specify and test. The circuits are evolved/synthesized in two different modes. The first mode explores an unstructured space, in which transistors can be interconnected freely in any arrangement (in simulations only). The second mode uses a Field Programmable Transistor Array (FPTA) model, and the circuit topology is sought as a mapping onto a programmable architecture (these experiments are performed both in simulations and on FPTA chips). The experiments demonstrated the synthesis. of polytronic circuits by evolution. The capacity of storing/hiding "extra" functions provides for watermark/invisible functionality, thus polytronics may find uses in intelligence/security applications.
A Computer Environment for Beginners' Learning of Sorting Algorithms: Design and Pilot Evaluation
ERIC Educational Resources Information Center
Kordaki, M.; Miatidis, M.; Kapsampelis, G.
2008-01-01
This paper presents the design, features and pilot evaluation study of a web-based environment--the SORTING environment--for the learning of sorting algorithms by secondary level education students. The design of this environment is based on modeling methodology, taking into account modern constructivist and social theories of learning while at…
Algorithm Design on Network Game of Chinese Chess
NASA Astrophysics Data System (ADS)
Xianmei, Fang
This paper describes the current situation of domestic network game. Contact the present condition of the local network game currently, we inquired to face to a multithread tcp client and server, such as Chinese chess, according to the information, and study the contents and meanings. Combining the Java of basic knowledge, the article study the compiling procedure facing to the object according to the information in Java Swing usage, and the method of the network procedure. The article researched the method and processes of the network procedure carry on the use of Sprocket under the Java Swing. Understood the basic process of compiling procedure using Java and how to compile a network procedure. The most importance is how a pair of machines correspondence-C/S the service system-is carried out. From here, we put forward the data structure,the basic calculate way of the network game- Chinese chess, and how to design and realize the server and client of that procedure. The online games -- chess design can be divided into several modules as follows: server module, client module and the control module.
On the impact of communication complexity in the design of parallel numerical algorithms
NASA Technical Reports Server (NTRS)
Gannon, D.; Vanrosendale, J.
1984-01-01
This paper describes two models of the cost of data movement in parallel numerical algorithms. One model is a generalization of an approach due to Hockney, and is suitable for shared memory multiprocessors where each processor has vector capabilities. The other model is applicable to highly parallel nonshared memory MIMD systems. In the second model, algorithm performance is characterized in terms of the communication network design. Techniques used in VLSI complexity theory are also brought in, and algorithm independent upper bounds on system performance are derived for several problems that are important to scientific computation.
A novel method to design S-box based on chaotic map and genetic algorithm
NASA Astrophysics Data System (ADS)
Wang, Yong; Wong, Kwok-Wo; Li, Changbing; Li, Yang
2012-01-01
The substitution box (S-box) is an important component in block encryption algorithms. In this Letter, the problem of constructing S-box is transformed to a Traveling Salesman Problem and a method for designing S-box based on chaos and genetic algorithm is proposed. Since the proposed method makes full use of the traits of chaotic map and evolution process, stronger S-box is obtained. The results of performance test show that the presented S-box has good cryptographic properties, which justify that the proposed algorithm is effective in generating strong S-boxes.
Phase Response Design of Recursive All-Pass Digital Filters Using a Modified PSO Algorithm
Chang, Wei-Der
2015-01-01
This paper develops a new design scheme for the phase response of an all-pass recursive digital filter. A variant of particle swarm optimization (PSO) algorithm will be utilized for solving this kind of filter design problem. It is here called the modified PSO (MPSO) algorithm in which another adjusting factor is more introduced in the velocity updating formula of the algorithm in order to improve the searching ability. In the proposed method, all of the designed filter coefficients are firstly collected to be a parameter vector and this vector is regarded as a particle of the algorithm. The MPSO with a modified velocity formula will force all particles into moving toward the optimal or near optimal solution by minimizing some defined objective function of the optimization problem. To show the effectiveness of the proposed method, two different kinds of linear phase response design examples are illustrated and the general PSO algorithm is compared as well. The obtained results show that the MPSO is superior to the general PSO for the phase response design of digital recursive all-pass filter. PMID:26366168
Chen, Deng-kai; Gu, Rong; Gu, Yu-feng; Yu, Sui-huai
2016-01-01
Consumers' Kansei needs reflect their perception about a product and always consist of a large number of adjectives. Reducing the dimension complexity of these needs to extract primary words not only enables the target product to be explicitly positioned, but also provides a convenient design basis for designers engaging in design work. Accordingly, this study employs a numerical design structure matrix (NDSM) by parameterizing a conventional DSM and integrating genetic algorithms to find optimum Kansei clusters. A four-point scale method is applied to assign link weights of every two Kansei adjectives as values of cells when constructing an NDSM. Genetic algorithms are used to cluster the Kansei NDSM and find optimum clusters. Furthermore, the process of the proposed method is presented. The details of the proposed approach are illustrated using an example of electronic scooter for Kansei needs clustering. The case study reveals that the proposed method is promising for clustering Kansei needs adjectives in product emotional design.
Li, Zong-Tao; Wu, Tie-Jun; Lin, Can-Long; Ma, Long-Hua
2011-01-01
A new generalized optimum strapdown algorithm with coning and sculling compensation is presented, in which the position, velocity and attitude updating operations are carried out based on the single-speed structure in which all computations are executed at a single updating rate that is sufficiently high to accurately account for high frequency angular rate and acceleration rectification effects. Different from existing algorithms, the updating rates of the coning and sculling compensations are unrelated with the number of the gyro incremental angle samples and the number of the accelerometer incremental velocity samples. When the output sampling rate of inertial sensors remains constant, this algorithm allows increasing the updating rate of the coning and sculling compensation, yet with more numbers of gyro incremental angle and accelerometer incremental velocity in order to improve the accuracy of system. Then, in order to implement the new strapdown algorithm in a single FPGA chip, the parallelization of the algorithm is designed and its computational complexity is analyzed. The performance of the proposed parallel strapdown algorithm is tested on the Xilinx ISE 12.3 software platform and the FPGA device XC6VLX550T hardware platform on the basis of some fighter data. It is shown that this parallel strapdown algorithm on the FPGA platform can greatly decrease the execution time of algorithm to meet the real-time and high precision requirements of system on the high dynamic environment, relative to the existing implemented on the DSP platform. PMID:22164058
Li, Zong-Tao; Wu, Tie-Jun; Lin, Can-Long; Ma, Long-Hua
2011-01-01
A new generalized optimum strapdown algorithm with coning and sculling compensation is presented, in which the position, velocity and attitude updating operations are carried out based on the single-speed structure in which all computations are executed at a single updating rate that is sufficiently high to accurately account for high frequency angular rate and acceleration rectification effects. Different from existing algorithms, the updating rates of the coning and sculling compensations are unrelated with the number of the gyro incremental angle samples and the number of the accelerometer incremental velocity samples. When the output sampling rate of inertial sensors remains constant, this algorithm allows increasing the updating rate of the coning and sculling compensation, yet with more numbers of gyro incremental angle and accelerometer incremental velocity in order to improve the accuracy of system. Then, in order to implement the new strapdown algorithm in a single FPGA chip, the parallelization of the algorithm is designed and its computational complexity is analyzed. The performance of the proposed parallel strapdown algorithm is tested on the Xilinx ISE 12.3 software platform and the FPGA device XC6VLX550T hardware platform on the basis of some fighter data. It is shown that this parallel strapdown algorithm on the FPGA platform can greatly decrease the execution time of algorithm to meet the real-time and high precision requirements of system on the high dynamic environment, relative to the existing implemented on the DSP platform. PMID:22164058
A Annealing Algorithm for Designing Ligands from Receptor Structures.
NASA Astrophysics Data System (ADS)
Zielinski, Peter J.
DEenspace NOVO, a simulated annealing method for designing ligands is described. At a given temperature, ligand fragments are randomly selected and randomly placed within the given receptor cavity, often replacing existing ligand fragments. For each new ligand fragment combination, bonded, nonbonded, polarization and solvation energies of the new ligand-receptor system are compared to the previous system. Acceptance or rejection of the new system is decided using the Boltzmann distribution. Thus, energetically unfavorable fragment switches are sometimes accepted, sacrificing immediate energy gains in the interest of finding the system with the globally minimum energy. By lowering the temperature, the rate of unfavorable switches decreases and energetically favorable combinations become difficult to change. The process is halted when the frequency of switches becomes too small. As a test of the method, DEenspace NOVO predicted the positions of important ligand fragments for neuraminidase that are in accord with the natural ligand, sialic acid.
Evolutionary algorithm for the neutrino factory front end design
Poklonskiy, Alexey A.; Neuffer, David; /Fermilab
2009-01-01
The Neutrino Factory is an important tool in the long-term neutrino physics program. Substantial effort is put internationally into designing this facility in order to achieve desired performance within the allotted budget. This accelerator is a secondary beam machine: neutrinos are produced by means of the decay of muons. Muons, in turn, are produced by the decay of pions, produced by hitting the target by a beam of accelerated protons suitable for acceleration. Due to the physics of this process, extra conditioning of the pion beam coming from the target is needed in order to effectively perform subsequent acceleration. The subsystem of the Neutrino Factory that performs this conditioning is called Front End, its main performance characteristic is the number of the produced muons.
New bionic navigation algorithm based on the visual navigation mechanism of bees
NASA Astrophysics Data System (ADS)
Huang, Yufeng; Liu, Yi; Liu, Jianguo
2015-04-01
Through some research on visual navigation mechanisms of flying insects especially honeybees, a novel navigation algorithm integrating entropy flow with Kalman filter has been introduced in this paper. Concepts of entropy image and entropy flow are also introduced, which can characterize topographic features and measure changes of the image respectively. To characterize texture feature and spatial distribution of an image, a new concept of contrast entropy image has been presented in this paper. Applying the contrast entropy image to the navigation algorithm to test its' performance of navigation and comparing with simulation results of intensity entropy image, a conclusion that contrast entropy image performs better and more robust in navigation has been made.
NASA Astrophysics Data System (ADS)
Lin, Jeng-Wen; Shen, Pu Fun; Wen, Hao-Ping
2015-10-01
The application of a repetitive control mechanism for use in a mechanical control system has been a topic of investigation. The fundamental purpose of repetitive control is to eliminate disturbances in a mechanical control system. This paper presents two different repetitive control laws using individual types of basis function feedback and their combinations. These laws adjust the command given to a feedback control system to eliminate tracking errors, generally resulting from periodic disturbance. Periodic errors can be reduced through linear basis functions using regression and a genetic algorithm. The results illustrate that repetitive control is most effective method for eliminating disturbances. When the data are stabilized, the tracking error of the obtained convergence value, 10-14, is the optimal solution, verifying that the proposed regression and genetic algorithm can satisfactorily reduce periodic errors.
The Design of Flux-Corrected Transport (FCT) Algorithms for Structured Grids
NASA Astrophysics Data System (ADS)
Zalesak, Steven T.
A given flux-corrected transport (FCT) algorithm consists of three components: (1) a high order algorithm to which it reduces in smooth parts of the flow; (2) a low order algorithm to which it reduces in parts of the flow devoid of smoothness; and (3) a flux limiter which calculates the weights assigned to the high and low order fluxes in various regions of the flow field. One way of optimizing an FCT algorithm is to optimize each of these three components individually. We present some of the ideas that have been developed over the past 30 years toward this end. These include the use of very high order spatial operators in the design of the high order fluxes, non-clipping flux limiters, the appropriate choice of constraint variables in the critical flux-limiting step, and the implementation of a "failsafe" flux-limiting strategy. This chapter confines itself to the design of FCT algorithms for structured grids, using a finite volume formalism, for this is the area with which the present author is most familiar. The reader will find excellent material on the design of FCT algorithms for unstructured grids, using both finite volume and finite element formalisms, in the chapters by Professors Löhner, Baum, Kuzmin, Turek, and Möller in the present volume.
Small, high pressure ratio compressor: Aerodynamic and mechanical design
NASA Technical Reports Server (NTRS)
Bryce, C. A.; Erwin, J. R.; Perrone, G. L.; Nelson, E. L.; Tu, R. K.; Bosco, A.
1973-01-01
The Small, High-Pressure-Ratio Compressor Program was directed toward the analysis, design, and fabrication of a centrifugal compressor providing a 6:1 pressure ratio and an airflow rate of 2.0 pounds per second. The program consists of preliminary design, detailed areodynamic design, mechanical design, and mechanical acceptance tests. The preliminary design evaluate radial- and backward-curved blades, tandem bladed impellers, impeller-and diffuser-passage boundary-layer control, and vane, pipe, and multiple-stage diffusers. Based on this evaluation, a configuration was selected for detailed aerodynamic and mechanical design. Mechanical acceptance test was performed to demonstrate that mechanical design objectives of the research package were met.
Epitope prediction algorithms for peptide-based vaccine design.
Florea, Liliana; Halldórsson, Bjarni; Kohlbacher, Oliver; Schwartz, Russell; Hoffman, Stephen; Istrail, Sorin
2003-01-01
Peptide-based vaccines, in which small peptides derived from target proteins (eptiopes) are used to provoke an immune reaction, have attracted considerable attention recently as a potential means both of treating infectious diseases and promoting the destruction of cancerous cells by a patient's own immune system. With the availability of large sequence databases and computers fast enough for rapid processing of large numbers of peptides, computer aided design of peptide-based vaccines has emerged as a promising approach to screening among billions of possible immune-active peptides to find those likely to provoke an immune response to a particular cell type. In this paper, we describe the development of three novel classes of methods for the prediction problem. We present a quadratic programming approach that can be trained on quantitative as well as qualitative data. The second method uses linear programming to counteract the fact that our training data contains mostly positive examples. The third class of methods uses sequence profiles obtained by clustering known epitopes to score candidate peptides. By integrating these methods, using a simple voting heuristic, we achieve improved accuracy over the state of the art. PMID:16826643
Uncertainty-based Optimization Algorithms in Designing Fractionated Spacecraft
Ning, Xin; Yuan, Jianping; Yue, Xiaokui
2016-01-01
A fractionated spacecraft is an innovative application of a distributive space system. To fully understand the impact of various uncertainties on its development, launch and in-orbit operation, we use the stochastic missioncycle cost to comprehensively evaluate the survivability, flexibility, reliability and economy of the ways of dividing the various modules of the different configurations of fractionated spacecraft. We systematically describe its concept and then analyze its evaluation and optimal design method that exists during recent years and propose the stochastic missioncycle cost for comprehensive evaluation. We also establish the models of the costs such as module development, launch and deployment and the impacts of their uncertainties respectively. Finally, we carry out the Monte Carlo simulation of the complete missioncycle costs of various configurations of the fractionated spacecraft under various uncertainties and give and compare the probability density distribution and statistical characteristics of its stochastic missioncycle cost, using the two strategies of timing module replacement and non-timing module replacement. The simulation results verify the effectiveness of the comprehensive evaluation method and show that our evaluation method can comprehensively evaluate the adaptability of the fractionated spacecraft under different technical and mission conditions. PMID:26964755
Uncertainty-based Optimization Algorithms in Designing Fractionated Spacecraft.
Ning, Xin; Yuan, Jianping; Yue, Xiaokui
2016-01-01
A fractionated spacecraft is an innovative application of a distributive space system. To fully understand the impact of various uncertainties on its development, launch and in-orbit operation, we use the stochastic missioncycle cost to comprehensively evaluate the survivability, flexibility, reliability and economy of the ways of dividing the various modules of the different configurations of fractionated spacecraft. We systematically describe its concept and then analyze its evaluation and optimal design method that exists during recent years and propose the stochastic missioncycle cost for comprehensive evaluation. We also establish the models of the costs such as module development, launch and deployment and the impacts of their uncertainties respectively. Finally, we carry out the Monte Carlo simulation of the complete missioncycle costs of various configurations of the fractionated spacecraft under various uncertainties and give and compare the probability density distribution and statistical characteristics of its stochastic missioncycle cost, using the two strategies of timing module replacement and non-timing module replacement. The simulation results verify the effectiveness of the comprehensive evaluation method and show that our evaluation method can comprehensively evaluate the adaptability of the fractionated spacecraft under different technical and mission conditions. PMID:26964755
Uncertainty-based Optimization Algorithms in Designing Fractionated Spacecraft
NASA Astrophysics Data System (ADS)
Ning, Xin; Yuan, Jianping; Yue, Xiaokui
2016-03-01
A fractionated spacecraft is an innovative application of a distributive space system. To fully understand the impact of various uncertainties on its development, launch and in-orbit operation, we use the stochastic missioncycle cost to comprehensively evaluate the survivability, flexibility, reliability and economy of the ways of dividing the various modules of the different configurations of fractionated spacecraft. We systematically describe its concept and then analyze its evaluation and optimal design method that exists during recent years and propose the stochastic missioncycle cost for comprehensive evaluation. We also establish the models of the costs such as module development, launch and deployment and the impacts of their uncertainties respectively. Finally, we carry out the Monte Carlo simulation of the complete missioncycle costs of various configurations of the fractionated spacecraft under various uncertainties and give and compare the probability density distribution and statistical characteristics of its stochastic missioncycle cost, using the two strategies of timing module replacement and non-timing module replacement. The simulation results verify the effectiveness of the comprehensive evaluation method and show that our evaluation method can comprehensively evaluate the adaptability of the fractionated spacecraft under different technical and mission conditions.
Integrated Turbopump Thermo-Mechanical Design and Analysis Tools
NASA Astrophysics Data System (ADS)
Platt, Mike
2002-07-01
This viewgraph presentation provides information on the thermo-mechanical design and analysis tools used to control the steady and transient thermo-mechanical effects which drive life, reliability, and cost. The thermo-mechanical analysis tools provide upfront design capability by effectively leveraging existing component design tools to analyze and control: fits, clearance, preload; cooling requirements; stress levels, LCF (low cycle fatigue) limits, and HCF (high cycle fatigue) margin.
Design of a blade stiffened composite panel by a genetic algorithm
NASA Technical Reports Server (NTRS)
Nagendra, S.; Haftka, R. T.; Gurdal, Z.
1993-01-01
Genetic algorithms (GAs) readily handle discrete problems, and can be made to generate many optima, as is presently illustrated for the case of design for minimum-weight stiffened panels with buckling constraints. The GA discrete design procedure proved superior to extant alternatives for both stiffened panels with cutouts and without cutouts. High computational costs are, however, associated with this discrete design approach at the current level of its development.
Design of a blade stiffened composite panel by a genetic algorithm
NASA Astrophysics Data System (ADS)
Nagendra, S.; Haftka, R. T.; Gurdal, Z.
1993-04-01
Genetic algorithms (GAs) readily handle discrete problems, and can be made to generate many optima, as is presently illustrated for the case of design for minimum-weight stiffened panels with buckling constraints. The GA discrete design procedure proved superior to extant alternatives for both stiffened panels with cutouts and without cutouts. High computational costs are, however, associated with this discrete design approach at the current level of its development.
Analysis and design of algorithm-based fault-tolerant systems
NASA Technical Reports Server (NTRS)
Nair, V. S. Sukumaran
1990-01-01
An important consideration in the design of high performance multiprocessor systems is to ensure the correctness of the results computed in the presence of transient and intermittent failures. Concurrent error detection and correction have been applied to such systems in order to achieve reliability. Algorithm Based Fault Tolerance (ABFT) was suggested as a cost-effective concurrent error detection scheme. The research was motivated by the complexity involved in the analysis and design of ABFT systems. To that end, a matrix-based model was developed and, based on that, algorithms for both the design and analysis of ABFT systems are formulated. These algorithms are less complex than the existing ones. In order to reduce the complexity further, a hierarchical approach is developed for the analysis of large systems.
Optimization of experimental design in fMRI: a general framework using a genetic algorithm.
Wager, Tor D; Nichols, Thomas E
2003-02-01
This article describes a method for selecting design parameters and a particular sequence of events in fMRI so as to maximize statistical power and psychological validity. Our approach uses a genetic algorithm (GA), a class of flexible search algorithms that optimize designs with respect to single or multiple measures of fitness. Two strengths of the GA framework are that (1) it operates with any sort of model, allowing for very specific parameterization of experimental conditions, including nonstandard trial types and experimentally observed scanner autocorrelation, and (2) it is flexible with respect to fitness criteria, allowing optimization over known or novel fitness measures. We describe how genetic algorithms may be applied to experimental design for fMRI, and we use the framework to explore the space of possible fMRI design parameters, with the goal of providing information about optimal design choices for several types of designs. In our simulations, we considered three fitness measures: contrast estimation efficiency, hemodynamic response estimation efficiency, and design counterbalancing. Although there are inherent trade-offs between these three fitness measures, GA optimization can produce designs that outperform random designs on all three criteria simultaneously. PMID:12595184
NASA Technical Reports Server (NTRS)
Tinker, Michael L.; Steincamp, James W.; Stewart, Eric T.; Patton, Bruce W.; Pannell, William P.; Newby, Ronald L.; Coffman, Mark E.; Qualls, A. L.; Bancroft, S.; Molvik, Greg
2003-01-01
The Nuclear Electric Vehicle Optimization Toolset (NEVOT) optimizes the design of all major Nuclear Electric Propulsion (NEP) vehicle subsystems for a defined mission within constraints and optimization parameters chosen by a user. The tool uses a Genetic Algorithm (GA) search technique to combine subsystem designs and evaluate the fitness of the integrated design to fulfill a mission. The fitness of an individual is used within the GA to determine its probability of survival through successive generations in which the designs with low fitness are eliminated and replaced with combinations or mutations of designs with higher fitness. The program can find optimal solutions for different sets of fitness metrics without modification and can create and evaluate vehicle designs that might never be conceived of through traditional design techniques. It is anticipated that the flexible optimization methodology will expand present knowledge of the design trade-offs inherent in designing nuclear powered space vehicles and lead to improved NEP designs.
MSFC Three Point Docking Mechanism design review
NASA Technical Reports Server (NTRS)
Schaefer, Otto; Ambrosio, Anthony
1992-01-01
In the next few decades, we will be launching expensive satellites and space platforms that will require recovery for economic reasons, because of initial malfunction, servicing, repairs, or out of a concern for post lifetime debris removal. The planned availability of a Three Point Docking Mechanism (TPDM) is a positive step towards an operational satellite retrieval infrastructure. This study effort supports NASA/MSFC engineering work in developing an automated docking capability. The work was performed by the Grumman Space & Electronics Group as a concept evaluation/test for the Tumbling Satellite Retrieval Kit. Simulation of a TPDM capture was performed in Grumman's Large Amplitude Space Simulator (LASS) using mockups of both parts (the mechanism and payload). Similar TPDM simulation activities and more extensive hardware testing was performed at NASA/MSFC in the Flight Robotics Laboratory and Space Station/Space Operations Mechanism Test Bed (6-DOF Facility).
A new second-order integration algorithm for simulating mechanical dynamic systems
NASA Technical Reports Server (NTRS)
Howe, R. M.
1989-01-01
A new integration algorithm which has the simplicity of Euler integration but exhibits second-order accuracy is described. In fixed-step numerical integration of differential equations for mechanical dynamic systems the method represents displacement and acceleration variables at integer step times and velocity variables at half-integer step times. Asymptotic accuracy of the algorithm is twice that of trapezoidal integration and ten times that of second-order Adams-Bashforth integration. The algorithm is also compatible with real-time inputs when used for a real-time simulation. It can be used to produce simulation outputs at double the integration frame rate, i.e., at both half-integer and integer frame times, even though it requires only one evaluation of state-variable derivatives per integration step. The new algorithm is shown to be especially effective in the simulation of lightly-damped structural modes. Both time-domain and frequency-domain accuracy comparisons with traditional integration methods are presented. Stability of the new algorithm is also examined.
Multidisciplinary Design, Analysis, and Optimization Tool Development Using a Genetic Algorithm
NASA Technical Reports Server (NTRS)
Pak, Chan-gi; Li, Wesley
2009-01-01
Multidisciplinary design, analysis, and optimization using a genetic algorithm is being developed at the National Aeronautics and Space Administration Dryden Flight Research Center (Edwards, California) to automate analysis and design process by leveraging existing tools to enable true multidisciplinary optimization in the preliminary design stage of subsonic, transonic, supersonic, and hypersonic aircraft. This is a promising technology, but faces many challenges in large-scale, real-world application. This report describes current approaches, recent results, and challenges for multidisciplinary design, analysis, and optimization as demonstrated by experience with the Ikhana fire pod design.!
Wang, Kung-Jeng; Adrian, Angelia Melani; Chen, Kun-Huang; Wang, Kung-Min
2015-04-01
Recently, the use of artificial intelligence based data mining techniques for massive medical data classification and diagnosis has gained its popularity, whereas the effectiveness and efficiency by feature selection is worthy to further investigate. In this paper, we presents a novel method for feature selection with the use of opposite sign test (OST) as a local search for the electromagnetism-like mechanism (EM) algorithm, denoted as improved electromagnetism-like mechanism (IEM) algorithm. Nearest neighbor algorithm is served as a classifier for the wrapper method. The proposed IEM algorithm is compared with nine popular feature selection and classification methods. Forty-six datasets from the UCI repository and eight gene expression microarray datasets are collected for comprehensive evaluation. Non-parametric statistical tests are conducted to justify the performance of the methods in terms of classification accuracy and Kappa index. The results confirm that the proposed IEM method is superior to the common state-of-art methods. Furthermore, we apply IEM to predict the occurrence of Type 2 diabetes mellitus (DM) after a gestational DM. Our research helps identify the risk factors for this disease; accordingly accurate diagnosis and prognosis can be achieved to reduce the morbidity and mortality rate caused by DM. PMID:25677947
The Balanced Cross-Layer Design Routing Algorithm in Wireless Sensor Networks Using Fuzzy Logic.
Li, Ning; Martínez, José-Fernán; Hernández Díaz, Vicente
2015-01-01
Recently, the cross-layer design for the wireless sensor network communication protocol has become more and more important and popular. Considering the disadvantages of the traditional cross-layer routing algorithms, in this paper we propose a new fuzzy logic-based routing algorithm, named the Balanced Cross-layer Fuzzy Logic (BCFL) routing algorithm. In BCFL, we use the cross-layer parameters' dispersion as the fuzzy logic inference system inputs. Moreover, we give each cross-layer parameter a dynamic weight according the value of the dispersion. For getting a balanced solution, the parameter whose dispersion is large will have small weight, and vice versa. In order to compare it with the traditional cross-layer routing algorithms, BCFL is evaluated through extensive simulations. The simulation results show that the new routing algorithm can handle the multiple constraints without increasing the complexity of the algorithm and can achieve the most balanced performance on selecting the next hop relay node. Moreover, the Balanced Cross-layer Fuzzy Logic routing algorithm can adapt to the dynamic changing of the network conditions and topology effectively. PMID:26266412
The Balanced Cross-Layer Design Routing Algorithm in Wireless Sensor Networks Using Fuzzy Logic
Li, Ning; Martínez, José-Fernán; Díaz, Vicente Hernández
2015-01-01
Recently, the cross-layer design for the wireless sensor network communication protocol has become more and more important and popular. Considering the disadvantages of the traditional cross-layer routing algorithms, in this paper we propose a new fuzzy logic-based routing algorithm, named the Balanced Cross-layer Fuzzy Logic (BCFL) routing algorithm. In BCFL, we use the cross-layer parameters’ dispersion as the fuzzy logic inference system inputs. Moreover, we give each cross-layer parameter a dynamic weight according the value of the dispersion. For getting a balanced solution, the parameter whose dispersion is large will have small weight, and vice versa. In order to compare it with the traditional cross-layer routing algorithms, BCFL is evaluated through extensive simulations. The simulation results show that the new routing algorithm can handle the multiple constraints without increasing the complexity of the algorithm and can achieve the most balanced performance on selecting the next hop relay node. Moreover, the Balanced Cross-layer Fuzzy Logic routing algorithm can adapt to the dynamic changing of the network conditions and topology effectively. PMID:26266412
Rolamite - A new mechanical design concept
NASA Technical Reports Server (NTRS)
Wilkes, D. F.
1967-01-01
Rolamite, a mechanical suspension system, provides substantial reductions in friction in the realm of extremely low bearing pressures. In addition, rolamite devices are easily microminiaturized, are extremely tolerant of production variations and are inherently capable of virtually all functions to construct most electromechanical devices.
The Design of Flux-Corrected Transport (FCT) Algorithms For Structured Grids
NASA Astrophysics Data System (ADS)
Zalesak, Steven T.
A given flux-corrected transport (FCT) algorithm consists of three components: 1) a high order algorithm to which it reduces in smooth parts of the flow; 2) a low order algorithm to which it reduces in parts of the flow devoid of smoothness; and 3) a flux limiter which calculates the weights assigned to the high and low order fluxes in various regions of the flow field. One way of optimizing an FCT algorithm is to optimize each of these three components individually. We present some of the ideas that have been developed over the past 30 years toward this end. These include the use of very high order spatial operators in the design of the high order fluxes, non-clipping flux limiters, the appropriate choice of constraint variables in the critical flux-limiting step, and the implementation of a "failsafe" flux-limiting strategy.
Validation of space/ground antenna control algorithms using a computer-aided design tool
NASA Technical Reports Server (NTRS)
Gantenbein, Rex E.
1995-01-01
The validation of the algorithms for controlling the space-to-ground antenna subsystem for Space Station Alpha is an important step in assuring reliable communications. These algorithms have been developed and tested using a simulation environment based on a computer-aided design tool that can provide a time-based execution framework with variable environmental parameters. Our work this summer has involved the exploration of this environment and the documentation of the procedures used to validate these algorithms. We have installed a variety of tools in a laboratory of the Tracking and Communications division for reproducing the simulation experiments carried out on these algorithms to verify that they do meet their requirements for controlling the antenna systems. In this report, we describe the processes used in these simulations and our work in validating the tests used.
Infrastructure Retrofit Design via Composite Mechanics
NASA Technical Reports Server (NTRS)
Chamis, Christos, C.; Gotsis,Pascal K.
1998-01-01
Select applications are described to illustrate the concept for retrofitting reinforced concrete infrastructure with fiber reinforced plastic laminates. The concept is first illustrated by using an axially loaded reinforced concrete column. A reinforced concrete arch and a dome are then used to illustrate the versatility of the concept. Advanced methods such as finite element structural analysis and progressive structural fracture are then used to evaluate the retrofitting laminate adequacy. Results obtains show that retrofits can be designed to double and even triple the as-designed load of the select reinforced concrete infrastructures.
The design and results of an algorithm for intelligent ground vehicles
NASA Astrophysics Data System (ADS)
Duncan, Matthew; Milam, Justin; Tote, Caleb; Riggins, Robert N.
2010-01-01
This paper addresses the design, design method, test platform, and test results of an algorithm used in autonomous navigation for intelligent vehicles. The Bluefield State College (BSC) team created this algorithm for its 2009 Intelligent Ground Vehicle Competition (IGVC) robot called Anassa V. The BSC robotics team is comprised of undergraduate computer science, engineering technology, marketing students, and one robotics faculty advisor. The team has participated in IGVC since the year 2000. A major part of the design process that the BSC team uses each year for IGVC is a fully documented "Post-IGVC Analysis." Over the nine years since 2000, the lessons the students learned from these analyses have resulted in an ever-improving, highly successful autonomous algorithm. The algorithm employed in Anassa V is a culmination of past successes and new ideas, resulting in Anassa V earning several excellent IGVC 2009 performance awards, including third place overall. The paper will discuss all aspects of the design of this autonomous robotic system, beginning with the design process and ending with test results for both simulation and real environments.
An Adaptive Defect Weighted Sampling Algorithm to Design Pseudoknotted RNA Secondary Structures.
Zandi, Kasra; Butler, Gregory; Kharma, Nawwaf
2016-01-01
Computational design of RNA sequences that fold into targeted secondary structures has many applications in biomedicine, nanotechnology and synthetic biology. An RNA molecule is made of different types of secondary structure elements and an important RNA element named pseudoknot plays a key role in stabilizing the functional form of the molecule. However, due to the computational complexities associated with characterizing pseudoknotted RNA structures, most of the existing RNA sequence designer algorithms generally ignore this important structural element and therefore limit their applications. In this paper we present a new algorithm to design RNA sequences for pseudoknotted secondary structures. We use NUPACK as the folding algorithm to compute the equilibrium characteristics of the pseudoknotted RNAs, and describe a new adaptive defect weighted sampling algorithm named Enzymer to design low ensemble defect RNA sequences for targeted secondary structures including pseudoknots. We used a biological data set of 201 pseudoknotted structures from the Pseudobase library to benchmark the performance of our algorithm. We compared the quality characteristics of the RNA sequences we designed by Enzymer with the results obtained from the state of the art MODENA and antaRNA. Our results show our method succeeds more frequently than MODENA and antaRNA do, and generates sequences that have lower ensemble defect, lower probability defect and higher thermostability. Finally by using Enzymer and by constraining the design to a naturally occurring and highly conserved Hammerhead motif, we designed 8 sequences for a pseudoknotted cis-acting Hammerhead ribozyme. Enzymer is available for download at https://bitbucket.org/casraz/enzymer. PMID:27499762
An Adaptive Defect Weighted Sampling Algorithm to Design Pseudoknotted RNA Secondary Structures
Zandi, Kasra; Butler, Gregory; Kharma, Nawwaf
2016-01-01
Computational design of RNA sequences that fold into targeted secondary structures has many applications in biomedicine, nanotechnology and synthetic biology. An RNA molecule is made of different types of secondary structure elements and an important RNA element named pseudoknot plays a key role in stabilizing the functional form of the molecule. However, due to the computational complexities associated with characterizing pseudoknotted RNA structures, most of the existing RNA sequence designer algorithms generally ignore this important structural element and therefore limit their applications. In this paper we present a new algorithm to design RNA sequences for pseudoknotted secondary structures. We use NUPACK as the folding algorithm to compute the equilibrium characteristics of the pseudoknotted RNAs, and describe a new adaptive defect weighted sampling algorithm named Enzymer to design low ensemble defect RNA sequences for targeted secondary structures including pseudoknots. We used a biological data set of 201 pseudoknotted structures from the Pseudobase library to benchmark the performance of our algorithm. We compared the quality characteristics of the RNA sequences we designed by Enzymer with the results obtained from the state of the art MODENA and antaRNA. Our results show our method succeeds more frequently than MODENA and antaRNA do, and generates sequences that have lower ensemble defect, lower probability defect and higher thermostability. Finally by using Enzymer and by constraining the design to a naturally occurring and highly conserved Hammerhead motif, we designed 8 sequences for a pseudoknotted cis-acting Hammerhead ribozyme. Enzymer is available for download at https://bitbucket.org/casraz/enzymer. PMID:27499762
NASA Astrophysics Data System (ADS)
Foudray, Angela Marie Klohs
Detecting, quantifying and visualizing biochemical mechanism in a living system without perturbing function is the goal of the instrument and algorithms designed in this thesis. Biochemical mechanisms of cells have long been known to be dependent on the signals they receive from their environment. Studying biological processes of cells in-vitro can vastly distort their function, since you are removing them from their natural chemical signaling environment. Mice have become the biological system of choice for various areas of biomedical research due to their genetic and physiological similarities with humans, the relatively low cost of their care, and their quick breeding cycle. Drug development and efficacy assessment along with disease detection, management, and mechanism research all have benefited from the use of small animal models of human disease. A high resolution, high sensitivity, three-dimensional (3D) positioning positron emission tomography (PET) detector system was designed through device characterization and Monte Carlo simulation. Position-sensitive avalanche photodiodes (PSAPDs) were characterized in various packaging configurations; coupled to various configurations of lutetium oxyorthosilicate (LSO) scintillation crystals. Forty novelly packaged final design devices were constructed and characterized, each providing characteristics superior to commercially available scintillation detectors used in small animal imaging systems: ˜1mm crystal identification, 14-15% of 511 keV energy resolution, and averaging 1.9 to 5.6 ns coincidence time resolution. A closed-cornered box-shaped detector configuration was found to provide optimal photon sensitivity (˜10.5% in the central plane) using dual LSO-PSAPD scintillation detector modules and Monte Carlo simulation. Standard figures of merit were used to determine optimal system acquisition parameters. A realistic model for constituent devices was developed for understanding the signals reported by the
Rationally designing the mechanical properties of protein hydrogels
NASA Astrophysics Data System (ADS)
Cao, Yi
Naturally occurring biomaterials possess diverse mechanical properties, which are critical to their unique biological functions. However, it remains challenging to rationally control the mechanical properties of synthetic biomaterials. Here we provide a bottom-up approach to rationally design the mechanical properties of protein-based hydrogels. We first use atomic fore microscope (AFM) based single-molecule force spectroscopy to characterize the mechanical stability of individual protein building blocks. We then rationally design the mechanical properties of hydrogels by selecting different combination of protein building blocks of known mechanical properties. As a proof-of-principle, we demonstrate the engineering of hydrogels of distinct extensibility and toughness. This simple combinatorial approach allows direct translation of the mechanical properties of proteins from the single molecule level to the macroscopic level and represents an important step towards rationally designing the mechanical properties of biomaterials.
A Proposal of CAD Mechanism for Design Knowledge Management
NASA Astrophysics Data System (ADS)
Nomaguchi, Yutaka; Yoshioka, Masaharu; Tomiyama, Tetsuo
In this paper, we propose a fundamental idea of a new CAD mechanism to facilitate design knowledge management. This mechanism encourages a designer to externalise his/her knowledge during a design process and facilitates sharing and reuse of such externalised design knowledge in later stages. We also describe the implementation of this idea called DDMS (Design Documentation Management System). DDMS works as a front end to KIEF (Knowledge Intensive Engineering Framework), which we have been developing. We also illustrate an example of machining tool design to demonstrate the features of DDMS.
The Mechanization of Design and Manufacturing.
ERIC Educational Resources Information Center
Gunn, Thomas G.
1982-01-01
Describes changes in the design of products and in planning, managing, and coordinating their manufacture. Focuses on discrete-products manufacturing industries, encompassing the fabrication and assembly of automobiles, aircraft, computers and microelectric components of computers, furniture, appliances, foods, clothing, building materials, and…
Designing berthing mechanisms for international compatibility
NASA Technical Reports Server (NTRS)
Winch, John; Gonzalez-Vallejo, Juan J.
1991-01-01
The paper examines the technological issues regarding common berthing interfaces for the Space Station Freedom and pressurized modules from U.S., European, and Japanese space programs. The development of the common berthing mechanism (CBM) is based on common requirements concerning specifications, launch environments, and the unique requirements of ESA's Man-Tended Free Flyer. The berthing mechanism is composed of an active and a passive half, a remote manipulator system, 4 capture-latch assemblies, 16 structural bolts, and a pressure gage to verify equalization. Extensive graphic and verbal descriptions of each element are presented emphasizing the capture-latch motion and powered-bolt operation. The support systems to complete the interface are listed, and the manufacturing requirements for consistent fabrication are discussed to ensure effective international development.
Dietrich, Arne; Haider, Hilde
2015-08-01
Creative thinking is arguably the pinnacle of cerebral functionality. Like no other mental faculty, it has been omnipotent in transforming human civilizations. Probing the neural basis of this most extraordinary capacity, however, has been doggedly frustrated. Despite a flurry of activity in cognitive neuroscience, recent reviews have shown that there is no coherent picture emerging from the neuroimaging work. Based on this, we take a different route and apply two well established paradigms to the problem. First is the evolutionary framework that, despite being part and parcel of creativity research, has no informed experimental work in cognitive neuroscience. Second is the emerging prediction framework that recognizes predictive representations as an integrating principle of all cognition. We show here how the prediction imperative revealingly synthesizes a host of new insights into the way brains process variation-selection thought trials and present a new neural mechanism for the partial sightedness in human creativity. Our ability to run offline simulations of expected future environments and action outcomes can account for some of the characteristic properties of cultural evolutionary algorithms running in brains, such as degrees of sightedness, the formation of scaffolds to jump over unviable intermediate forms, or how fitness criteria are set for a selection process that is necessarily hypothetical. Prospective processing in the brain also sheds light on how human creating and designing - as opposed to biological creativity - can be accompanied by intentions and foresight. This paper raises questions about the nature of creative thought that, as far as we know, have never been asked before. PMID:25304474
Design and Optimization of Low-thrust Orbit Transfers Using Q-law and Evolutionary Algorithms
NASA Technical Reports Server (NTRS)
Lee, Seungwon; vonAllmen, Paul; Fink, Wolfgang; Petropoulos, Anastassios; Terrile, Richard
2005-01-01
Future space missions will depend more on low-thrust propulsion (such as ion engines) thanks to its high specific impulse. Yet, the design of low-thrust trajectories is complex and challenging. Third-body perturbations often dominate the thrust, and a significant change to the orbit requires a long duration of thrust. In order to guide the early design phases, we have developed an efficient and efficacious method to obtain approximate propellant and flight-time requirements (i.e., the Pareto front) for orbit transfers. A search for the Pareto-optimal trajectories is done in two levels: optimal thrust angles and locations are determined by Q-law, while the Q-law is optimized with two evolutionary algorithms: a genetic algorithm and a simulated-annealing-related algorithm. The examples considered are several types of orbit transfers around the Earth and the asteroid Vesta.
General parameter relations for the Shinnar-Le Roux pulse design algorithm.
Lee, Kuan J
2007-06-01
The magnetization ripple amplitudes from a pulse designed by the Shinnar-Le Roux algorithm are a non-linear function of the Shinnar-Le Roux A and B polynomial ripples. In this paper, the method of Pauly et al. [J. Pauly, P. Le Roux, D. Nishimura, A. Macovski, Parameter relations for the Shinnar-Le Roux selective excitation pulse design algorithm, IEEE Transactions on Medical Imaging 10 (1991) 56-65.] has been extended to derive more general parameter relations. These relations can be used for cases outside the five classes considered by Pauly et al., in particular excitation pulses for flip angles that are not small or 90 degrees. Use of the new relations, together with an iterative procedure to obtain polynomials with the specified ripples from the Parks-McClellan algorithm, are shown to give simulated slice profiles that have the desired ripple amplitudes. PMID:17408999
A Dynamic Programming Algorithm for Optimal Design of Tidal Power Plants
NASA Astrophysics Data System (ADS)
Nag, B.
2013-03-01
A dynamic programming algorithm is proposed and demonstrated on a test case to determine the optimum operating schedule of a barrage tidal power plant to maximize the energy generation over a tidal cycle. Since consecutive sets of high and low tides can be predicted accurately for any tidal power plant site, this algorithm can be used to calculate the annual energy generation for different technical configurations of the plant. Thus an optimal choice of a tidal power plant design can be made from amongst different design configurations yielding the least cost of energy generation. Since this algorithm determines the optimal time of operation of sluice gate opening and turbine gates opening to maximize energy generation over a tidal cycle, it can also be used to obtain the annual schedule of operation of a tidal power plant and the minute-to-minute energy generation, for dissemination amongst power distribution utilities.
Improved Cost-Base Design of Water Distribution Networks using Genetic Algorithm
NASA Astrophysics Data System (ADS)
Moradzadeh Azar, Foad; Abghari, Hirad; Taghi Alami, Mohammad; Weijs, Steven
2010-05-01
Population growth and progressive extension of urbanization in different places of Iran cause an increasing demand for primary needs. The water, this vital liquid is the most important natural need for human life. Providing this natural need is requires the design and construction of water distribution networks, that incur enormous costs on the country's budget. Any reduction in these costs enable more people from society to access extreme profit least cost. Therefore, investment of Municipal councils need to maximize benefits or minimize expenditures. To achieve this purpose, the engineering design depends on the cost optimization techniques. This paper, presents optimization models based on genetic algorithm(GA) to find out the minimum design cost Mahabad City's (North West, Iran) water distribution network. By designing two models and comparing the resulting costs, the abilities of GA were determined. the GA based model could find optimum pipe diameters to reduce the design costs of network. Results show that the water distribution network design using Genetic Algorithm could lead to reduction of at least 7% in project costs in comparison to the classic model. Keywords: Genetic Algorithm, Optimum Design of Water Distribution Network, Mahabad City, Iran.
Genetic algorithms in conceptual design of a light-weight, low-noise, tilt-rotor aircraft
NASA Technical Reports Server (NTRS)
Wells, Valana L.
1996-01-01
This report outlines research accomplishments in the area of using genetic algorithms (GA) for the design and optimization of rotorcraft. It discusses the genetic algorithm as a search and optimization tool, outlines a procedure for using the GA in the conceptual design of helicopters, and applies the GA method to the acoustic design of rotors.
Mechanical design of the VISA undulator
Libkind, M.; Bertolini, L.; Duffy, P.; Carr, R.; Ratowsky, G.; Skarita, J.
1999-03-01
As part of the research and development effort for a 4th generation light source, we have designed a 4-meter long Free-Electron Laser (FEL) undulator. The undulator will be installed at the Accelerator Test Facility (ATF) at Brookhaven National Laboratory to conduct a Self-Amplified Spontaneous Emission (SASE) demonstration. The demonstration is called VISA, which stands for "Visible to Infrared SASE Amplifier." The undulator consists of 440 permanent dipole magnets per meter which are supported and aligned on a precision strongback. Focusing and defocusing permanent quadrupole magnets are also supported by the strongback. Each of the 4 one-meter sections of undulator are kinematically supported and housed within the vacuum vessel. The undulator and the vacuum vessel are supported independently to eliminate undulator misalignment during vacuum pump-down of the vessel. We describe the design requirements and features of the undulator, vacuum vessel and support system.
Opto-mechanical design of FRIDA
NASA Astrophysics Data System (ADS)
Bringas, V.; Lucero, D.; Uribe, J.; Rodríguez, A.; Montoya, J. M.; Estrada, R.; Álvarez, L.; Gómez, E.; Sánchez, B.; Cuevas, S.; Espejo, C.; Flores, R.; Keiman, C.; Chapa, O.; Lara, G.; Eikenberry, S. S.
2013-05-01
FRIDA (inFRrared Imager and Dissector for the Adaptive optics system of the Gran Telescopio Canarias) is being designed as cryogenic and diffraction limited instrument that will offer with broad and narrow band imaging and integral field spectroscopy capabilities with Low (R=1400), intermediate (R=4000) and high (R=30000) to operate in the wavelength range 0.9-2.4 μm.
Mechanism Design Principle for Optical-Precision, Deployable Instruments
NASA Technical Reports Server (NTRS)
Lake, Mark S.; Hachkowski, M. Roman
2000-01-01
The present paper is intended to be a guide for the design of 'microdynamically quiet' deployment mechanisms for optical-precision structures, such as deployable telescope mirrors and optical benches. Many of the guidelines included herein come directly from the field of optomechanical engineering, and are neither newly developed guidelines nor are they uniquely applicable to high-precision deployment mechanisms. However, the application of these guidelines to the design of deployment mechanisms is a rather new practice, so efforts are made herein to illustrate the process through the discussion of specific examples. The present paper summarizes a more extensive set of design guidelines for optical-precision mechanisms that are under development.
Automatic design of decision-tree induction algorithms tailored to flexible-receptor docking data
2012-01-01
Background This paper addresses the prediction of the free energy of binding of a drug candidate with enzyme InhA associated with Mycobacterium tuberculosis. This problem is found within rational drug design, where interactions between drug candidates and target proteins are verified through molecular docking simulations. In this application, it is important not only to correctly predict the free energy of binding, but also to provide a comprehensible model that could be validated by a domain specialist. Decision-tree induction algorithms have been successfully used in drug-design related applications, specially considering that decision trees are simple to understand, interpret, and validate. There are several decision-tree induction algorithms available for general-use, but each one has a bias that makes it more suitable for a particular data distribution. In this article, we propose and investigate the automatic design of decision-tree induction algorithms tailored to particular drug-enzyme binding data sets. We investigate the performance of our new method for evaluating binding conformations of different drug candidates to InhA, and we analyze our findings with respect to decision tree accuracy, comprehensibility, and biological relevance. Results The empirical analysis indicates that our method is capable of automatically generating decision-tree induction algorithms that significantly outperform the traditional C4.5 algorithm with respect to both accuracy and comprehensibility. In addition, we provide the biological interpretation of the rules generated by our approach, reinforcing the importance of comprehensible predictive models in this particular bioinformatics application. Conclusions We conclude that automatically designing a decision-tree algorithm tailored to molecular docking data is a promising alternative for the prediction of the free energy from the binding of a drug candidate with a flexible-receptor. PMID:23171000
MECHANICAL DESIGN OF NSLS MINI - GAP UNDULATOR (MGU)
LYNCH,D.; RAKOWSKY,G.
2002-09-05
The mechanical design considerations are discussed with respect to the currently installed X-13 and future X-29 MGU. Comparisons to the previous 2 generations of variable small-gap undulator evolution in the NSLS X-ray ring are made and design improvements noted. The design requirements and mechanical difficulties for holding, positioning and driving the magnetic arrays are explored. Structural, thermal and electrical considerations which influenced the design are then analyzed. The mechanical performance of the MGU currently installed at X-13 is examined and future installations and enhancements are presented.
Optimal high speed CMOS inverter design using craziness based Particle Swarm Optimization Algorithm
NASA Astrophysics Data System (ADS)
De, Bishnu P.; Kar, Rajib; Mandal, Durbadal; Ghoshal, Sakti P.
2015-07-01
The inverter is the most fundamental logic gate that performs a Boolean operation on a single input variable. In this paper, an optimal design of CMOS inverter using an improved version of particle swarm optimization technique called Craziness based Particle Swarm Optimization (CRPSO) is proposed. CRPSO is very simple in concept, easy to implement and computationally efficient algorithm with two main advantages: it has fast, nearglobal convergence, and it uses nearly robust control parameters. The performance of PSO depends on its control parameters and may be influenced by premature convergence and stagnation problems. To overcome these problems the PSO algorithm has been modiffed to CRPSO in this paper and is used for CMOS inverter design. In birds' flocking or ffsh schooling, a bird or a ffsh often changes direction suddenly. In the proposed technique, the sudden change of velocity is modelled by a direction reversal factor associated with the previous velocity and a "craziness" velocity factor associated with another direction reversal factor. The second condition is introduced depending on a predeffned craziness probability to maintain the diversity of particles. The performance of CRPSO is compared with real code.gnetic algorithm (RGA), and conventional PSO reported in the recent literature. CRPSO based design results are also compared with the PSPICE based results. The simulation results show that the CRPSO is superior to the other algorithms for the examples considered and can be efficiently used for the CMOS inverter design.
A new adaptive merging and growing algorithm for designing artificial neural networks.
Islam, Md Monirul; Sattar, Md Abdus; Amin, Md Faijul; Yao, Xin; Murase, Kazuyuki
2009-06-01
This paper presents a new algorithm, called adaptive merging and growing algorithm (AMGA), in designing artificial neural networks (ANNs). This algorithm merges and adds hidden neurons during the training process of ANNs. The merge operation introduced in AMGA is a kind of a mixed mode operation, which is equivalent to pruning two neurons and adding one neuron. Unlike most previous studies, AMGA puts emphasis on autonomous functioning in the design process of ANNs. This is the main reason why AMGA uses an adaptive not a predefined fixed strategy in designing ANNs. The adaptive strategy merges or adds hidden neurons based on the learning ability of hidden neurons or the training progress of ANNs. In order to reduce the amount of retraining after modifying ANN architectures, AMGA prunes hidden neurons by merging correlated hidden neurons and adds hidden neurons by splitting existing hidden neurons. The proposed AMGA has been tested on a number of benchmark problems in machine learning and ANNs, including breast cancer, Australian credit card assessment, and diabetes, gene, glass, heart, iris, and thyroid problems. The experimental results show that AMGA can design compact ANN architectures with good generalization ability compared to other algorithms. PMID:19203888
The Impact of Critical Thinking and Logico-Mathematical Intelligence on Algorithmic Design Skills
ERIC Educational Resources Information Center
Korkmaz, Ozgen
2012-01-01
The present study aims to reveal the impact of students' critical thinking and logico-mathematical intelligence levels of students on their algorithm design skills. This research was a descriptive study and carried out by survey methods. The sample consisted of 45 first-year educational faculty undergraduate students. The data was collected by…
NASA Technical Reports Server (NTRS)
Collins, Emmanuel G., Jr.; Richter, Stephen
1990-01-01
One well known deficiency of LQG compensators is that they do not guarantee any measure of robustness. This deficiency is especially highlighted when considering control design for complex systems such as flexible structures. There has thus been a need to generalize LQG theory to incorporate robustness constraints. Here we describe the maximum entropy approach to robust control design for flexible structures, a generalization of LQG theory, pioneered by Hyland, which has proved useful in practice. The design equations consist of a set of coupled Riccati and Lyapunov equations. A homotopy algorithm that is used to solve these design equations is presented.
Multidisciplinary Design, Analysis, and Optimization Tool Development using a Genetic Algorithm
NASA Technical Reports Server (NTRS)
Pak, Chan-gi; Li, Wesley
2008-01-01
Multidisciplinary design, analysis, and optimization using a genetic algorithm is being developed at the National Aeronautics and Space A dministration Dryden Flight Research Center to automate analysis and design process by leveraging existing tools such as NASTRAN, ZAERO a nd CFD codes to enable true multidisciplinary optimization in the pr eliminary design stage of subsonic, transonic, supersonic, and hypers onic aircraft. This is a promising technology, but faces many challe nges in large-scale, real-world application. This paper describes cur rent approaches, recent results, and challenges for MDAO as demonstr ated by our experience with the Ikhana fire pod design.
2014-01-01
Background To improve the tedious task of reconstructing gene networks through testing experimentally the possible interactions between genes, it becomes a trend to adopt the automated reverse engineering procedure instead. Some evolutionary algorithms have been suggested for deriving network parameters. However, to infer large networks by the evolutionary algorithm, it is necessary to address two important issues: premature convergence and high computational cost. To tackle the former problem and to enhance the performance of traditional evolutionary algorithms, it is advisable to use parallel model evolutionary algorithms. To overcome the latter and to speed up the computation, it is advocated to adopt the mechanism of cloud computing as a promising solution: most popular is the method of MapReduce programming model, a fault-tolerant framework to implement parallel algorithms for inferring large gene networks. Results This work presents a practical framework to infer large gene networks, by developing and parallelizing a hybrid GA-PSO optimization method. Our parallel method is extended to work with the Hadoop MapReduce programming model and is executed in different cloud computing environments. To evaluate the proposed approach, we use a well-known open-source software GeneNetWeaver to create several yeast S. cerevisiae sub-networks and use them to produce gene profiles. Experiments have been conducted and the results have been analyzed. They show that our parallel approach can be successfully used to infer networks with desired behaviors and the computation time can be largely reduced. Conclusions Parallel population-based algorithms can effectively determine network parameters and they perform better than the widely-used sequential algorithms in gene network inference. These parallel algorithms can be distributed to the cloud computing environment to speed up the computation. By coupling the parallel model population-based optimization method and the parallel
The design of a parallel adaptive paving all-quadrilateral meshing algorithm
Tautges, T.J.; Lober, R.R.; Vaughan, C.
1995-08-01
Adaptive finite element analysis demands a great deal of computational resources, and as such is most appropriately solved in a massively parallel computer environment. This analysis will require other parallel algorithms before it can fully utilize MP computers, one of which is parallel adaptive meshing. A version of the paving algorithm is being designed which operates in parallel but which also retains the robustness and other desirable features present in the serial algorithm. Adaptive paving in a production mode is demonstrated using a Babuska-Rheinboldt error estimator on a classic linearly elastic plate problem. The design of the parallel paving algorithm is described, and is based on the decomposition of a surface into {open_quotes}virtual{close_quotes} surfaces. The topology of the virtual surface boundaries is defined using mesh entities (mesh nodes and edges) so as to allow movement of these boundaries with smoothing and other operations. This arrangement allows the use of the standard paving algorithm on subdomain interiors, after the negotiation of the boundary mesh.
Data Sharing of Mechanical Design Formulas Using Semantic Web Technology
NASA Astrophysics Data System (ADS)
Zhou, Jun; Watanuki, Keiichi
Speed and efficiency are necessary in the field of mechanical design. CAD/CAM/CAE technologies have advanced and attention has also been paid to increasing the efficiency of data sharing and agent processes in the web environment. In this paper, Semantic Web technology is used to enable the sharing of metadata. The metadata consists of design documents and design formulas, with additional semantic information inserted. Mathematical information is expressed by adding metadata into conventional mechanical design formulas using a Resource Description Framework (RDF). The design formulas are later written in MathML (Mathematical Markup Language) for the sake of data sharing. In this way, data sharing and advanced searching is made easy, because the relevant information is made machine readable in the web environment. The calculation of design formulas is made possible using a mathematical processing system, thus increasing the efficiency of mechanical design.
Integrating Thermal Tools Into the Mechanical Design Process
NASA Technical Reports Server (NTRS)
Tsuyuki, Glenn T.; Siebes, Georg; Novak, Keith S.; Kinsella, Gary M.
1999-01-01
The intent of mechanical design is to deliver a hardware product that meets or exceeds customer expectations, while reducing cycle time and cost. To this end, an integrated mechanical design process enables the idea of parallel development (concurrent engineering). This represents a shift from the traditional mechanical design process. With such a concurrent process, there are significant issues that have to be identified and addressed before re-engineering the mechanical design process to facilitate concurrent engineering. These issues also assist in the integration and re-engineering of the thermal design sub-process since it resides within the entire mechanical design process. With these issues in mind, a thermal design sub-process can be re-defined in a manner that has a higher probability of acceptance, thus enabling an integrated mechanical design process. However, the actual implementation is not always problem-free. Experience in applying the thermal design sub-process to actual situations provides the evidence for improvement, but more importantly, for judging the viability and feasibility of the sub-process.
Thermoluminescence curves simulation using genetic algorithm with factorial design
NASA Astrophysics Data System (ADS)
Popko, E. A.; Weinstein, I. A.
2016-05-01
The evolutionary approach is an effective optimization tool for numeric analysis of thermoluminescence (TL) processes to assess the microparameters of kinetic models and to determine its effects on the shape of TL peaks. In this paper, the procedure for tuning of genetic algorithm (GA) is presented. This approach is based on multifactorial experiment and allows choosing intrinsic mechanisms of evolutionary operators which provide the most efficient algorithm performance. The proposed method is tested by considering the “one trap-one recombination center” (OTOR) model as an example and advantages for approximation of experimental TL curves are shown.
Preliminary Opto-Mechanical Design for the X2000 Transceiver
NASA Technical Reports Server (NTRS)
Hemmati, H.; Page, N. A.
2000-01-01
Preliminary optical design and mechanical conceptual design for a 30 cm aperture transceiver are described. A common aperture is used for both transmit and receive. Special attention was given to off-axis and scattered light rejection and isolation of the receive channel from the transmit channel. Requirements, details of the design and preliminary performance analysis of the transceiver are provided.
Mechanical design of submarine power cables for floating platforms
Bisplinghoff, R. L.; Libby, D. O.; Costantino, R. W.
1980-01-01
The process of mechanical design of submarine power cables employed by the Simplex Wire and Cable Company is described. The process commences with design criteria and proceeds through preliminary design, load and stress analyses and culminates in extreme value reliability and lifetime predictions. The analytical methods employed are emphasized and some representative numerical results are presented.
Mechanical Design of the LSST Camera
Nordby, Martin; Bowden, Gordon; Foss, Mike; Guiffre, Gary; Ku, John; Schindler, Rafe; /SLAC
2008-06-13
The LSST camera is a tightly packaged, hermetically-sealed system that is cantilevered into the main beam of the LSST telescope. It is comprised of three refractive lenses, on-board storage for five large filters, a high-precision shutter, and a cryostat that houses the 3.2 giga-pixel CCD focal plane along with its support electronics. The physically large optics and focal plane demand large structural elements to support them, but the overall size of the camera and its components must be minimized to reduce impact on the image stability. Also, focal plane and optics motions must be minimized to reduce systematic errors in image reconstruction. Design and analysis for the camera body and cryostat will be detailed.
Integrating a Genetic Algorithm Into a Knowledge-Based System for Ordering Complex Design Processes
NASA Technical Reports Server (NTRS)
Rogers, James L.; McCulley, Collin M.; Bloebaum, Christina L.
1996-01-01
The design cycle associated with large engineering systems requires an initial decomposition of the complex system into design processes which are coupled through the transference of output data. Some of these design processes may be grouped into iterative subcycles. In analyzing or optimizing such a coupled system, it is essential to be able to determine the best ordering of the processes within these subcycles to reduce design cycle time and cost. Many decomposition approaches assume the capability is available to determine what design processes and couplings exist and what order of execution will be imposed during the design cycle. Unfortunately, this is often a complex problem and beyond the capabilities of a human design manager. A new feature, a genetic algorithm, has been added to DeMAID (Design Manager's Aid for Intelligent Decomposition) to allow the design manager to rapidly examine many different combinations of ordering processes in an iterative subcycle and to optimize the ordering based on cost, time, and iteration requirements. Two sample test cases are presented to show the effects of optimizing the ordering with a genetic algorithm.
DeMAID/GA USER'S GUIDE Design Manager's Aid for Intelligent Decomposition with a Genetic Algorithm
NASA Technical Reports Server (NTRS)
Rogers, James L.
1996-01-01
Many companies are looking for new tools and techniques to aid a design manager in making decisions that can reduce the time and cost of a design cycle. One tool that is available to aid in this decision making process is the Design Manager's Aid for Intelligent Decomposition (DeMAID). Since the initial release of DEMAID in 1989, numerous enhancements have been added to aid the design manager in saving both cost and time in a design cycle. The key enhancement is a genetic algorithm (GA) and the enhanced version is called DeMAID/GA. The GA orders the sequence of design processes to minimize the cost and time to converge to a solution. These enhancements as well as the existing features of the original version of DEMAID are described. Two sample problems are used to show how these enhancements can be applied to improve the design cycle. This report serves as a user's guide for DeMAID/GA.
Sizing of complex structure by the integration of several different optimal design algorithms
NASA Technical Reports Server (NTRS)
Sobieszczanski, J.
1974-01-01
Practical design of large-scale structures can be accomplished with the aid of the digital computer by bringing together in one computer program algorithms of nonlinear mathematical programing and optimality criteria with weight-strength and other so-called engineering methods. Applications of this approach to aviation structures are discussed with a detailed description of how the total problem of structural sizing can be broken down into subproblems for best utilization of each algorithm and for efficient organization of the program into iterative loops. Typical results are examined for a number of examples.
Homotopy Algorithm for Fixed Order Mixed H2/H(infinity) Design
NASA Technical Reports Server (NTRS)
Whorton, Mark; Buschek, Harald; Calise, Anthony J.
1996-01-01
Recent developments in the field of robust multivariable control have merged the theories of H-infinity and H-2 control. This mixed H-2/H-infinity compensator formulation allows design for nominal performance by H-2 norm minimization while guaranteeing robust stability to unstructured uncertainties by constraining the H-infinity norm. A key difficulty associated with mixed H-2/H-infinity compensation is compensator synthesis. A homotopy algorithm is presented for synthesis of fixed order mixed H-2/H-infinity compensators. Numerical results are presented for a four disk flexible structure to evaluate the efficiency of the algorithm.
A firefly algorithm for solving competitive location-design problem: a case study
NASA Astrophysics Data System (ADS)
Sadjadi, Seyed Jafar; Ashtiani, Milad Gorji; Ramezanian, Reza; Makui, Ahmad
2016-07-01
This paper aims at determining the optimal number of new facilities besides specifying both the optimal location and design level of them under the budget constraint in a competitive environment by a novel hybrid continuous and discrete firefly algorithm. A real-world application of locating new chain stores in the city of Tehran, Iran, is used and the results are analyzed. In addition, several examples have been solved to evaluate the efficiency of the proposed model and algorithm. The results demonstrate that the performed method provides good-quality results for the test problems.
Evolving spiking neural networks: a novel growth algorithm exhibits unintelligent design
NASA Astrophysics Data System (ADS)
Schaffer, J. David
2015-06-01
Spiking neural networks (SNNs) have drawn considerable excitement because of their computational properties, believed to be superior to conventional von Neumann machines, and sharing properties with living brains. Yet progress building these systems has been limited because we lack a design methodology. We present a gene-driven network growth algorithm that enables a genetic algorithm (evolutionary computation) to generate and test SNNs. The genome for this algorithm grows O(n) where n is the number of neurons; n is also evolved. The genome not only specifies the network topology, but all its parameters as well. Experiments show the algorithm producing SNNs that effectively produce a robust spike bursting behavior given tonic inputs, an application suitable for central pattern generators. Even though evolution did not include perturbations of the input spike trains, the evolved networks showed remarkable robustness to such perturbations. In addition, the output spike patterns retain evidence of the specific perturbation of the inputs, a feature that could be exploited by network additions that could use this information for refined decision making if required. On a second task, a sequence detector, a discriminating design was found that might be considered an example of "unintelligent design"; extra non-functional neurons were included that, while inefficient, did not hamper its proper functioning.
Use of the particle swarm optimization algorithm for second order design of levelling networks
NASA Astrophysics Data System (ADS)
Yetkin, Mevlut; Inal, Cevat; Yigit, Cemal Ozer
2009-08-01
The weight problem in geodetic networks can be dealt with as an optimization procedure. This classic problem of geodetic network optimization is also known as second-order design. The basic principles of geodetic network optimization are reviewed. Then the particle swarm optimization (PSO) algorithm is applied to a geodetic levelling network in order to solve the second-order design problem. PSO, which is an iterative-stochastic search algorithm in swarm intelligence, emulates the collective behaviour of bird flocking, fish schooling or bee swarming, to converge probabilistically to the global optimum. Furthermore, it is a powerful method because it is easy to implement and computationally efficient. Second-order design of a geodetic levelling network using PSO yields a practically realizable solution. It is also suitable for non-linear matrix functions that are very often encountered in geodetic network optimization. The fundamentals of the method and a numeric example are given.
Adjoint-Based Algorithms for Adaptation and Design Optimizations on Unstructured Grids
NASA Technical Reports Server (NTRS)
Nielsen, Eric J.
2006-01-01
Schemes based on discrete adjoint algorithms present several exciting opportunities for significantly advancing the current state of the art in computational fluid dynamics. Such methods provide an extremely efficient means for obtaining discretely consistent sensitivity information for hundreds of design variables, opening the door to rigorous, automated design optimization of complex aerospace configuration using the Navier-Stokes equation. Moreover, the discrete adjoint formulation provides a mathematically rigorous foundation for mesh adaptation and systematic reduction of spatial discretization error. Error estimates are also an inherent by-product of an adjoint-based approach, valuable information that is virtually non-existent in today's large-scale CFD simulations. An overview of the adjoint-based algorithm work at NASA Langley Research Center is presented, with examples demonstrating the potential impact on complex computational problems related to design optimization as well as mesh adaptation.
A general design algorithm for low optical loss adiabatic connections in waveguides.
Chen, Tong; Lee, Hansuek; Li, Jiang; Vahala, Kerry J
2012-09-24
Single-mode waveguide designs frequently support higher order transverse modes, usually as a consequence of process limitations such as lithography. In these systems, it is important to minimize coupling to higher-order modes so that the system nonetheless behaves single mode. We propose a variational approach to design adiabatic waveguide connections with minimal intermodal coupling. An application of this algorithm in designing the "S-bend" of a whispering-gallery spiral waveguide is demonstrated with approximately 0.05 dB insertion loss. Compared to other approaches, our algorithm requires less fabrication resolution and is able to minimize the transition loss over a broadband spectrum. The method can be applied to a wide range of turns and connections and has the advantage of handling connections with arbitrary boundary conditions. PMID:23037432
Design and Implementation of IIR Algorithms for Control of Longitudinal Coupled-Bunch Instabilities
Teytelman, Dmitry
2000-05-16
The recent installation of third-harmonic RF cavities at the Advanced Light Source has raised instability growth rates, and also caused tune shifts (coherent and incoherent) of more than an octave over the required range of beam currents and energies. The larger growth rates and tune shifts have rendered control by the original bandpass FIR feedback algorithms unreliable. In this paper the authors describe an implementation of an IIR feedback algorithm with more exible response tailoring. A cascade of up to 6 second-order IIR sections (12 poles and 12 zeros) was implemented in the DSPs of the longitudinal feedback system. Filter design has been formulated as an optimization problem and solved using constrained optimization methods. These IIR filters provided 2.4 times the control bandwidth as compared to the original FIR designs. Here the authors demonstrate the performance of the designed filters using transient diagnostic measurements from ALS and DAPNE.
Mechanical design of a power-adjustable spectacle lens frame
NASA Astrophysics Data System (ADS)
Zapata, Asuncion; Barbero, Sergio
2011-05-01
Power-adjustable spectacle lenses, based on the Alvarez-Lohmann principle, can be used to provide affordable spectacles for subjective refractive errors measurement and its correction. A new mechanical frame has been designed to maximize the advantages of this technology. The design includes a mechanism to match the interpupillary distance with that of the optical centers of the lenses. The frame can be manufactured using low cost plastic injection molding techniques. A prototype has been built to test the functioning of this mechanical design.
NASA Astrophysics Data System (ADS)
Son, Min; Ko, Sangho; Koo, Jaye
2014-06-01
A genetic algorithm was used to develop optimal design methods for the regenerative cooled combustor and fuel-rich gas generator of a liquid rocket engine. For the combustor design, a chemical equilibrium analysis was applied, and the profile was calculated using Rao's method. One-dimensional heat transfer was assumed along the profile, and cooling channels were designed. For the gas-generator design, non-equilibrium properties were derived from a counterflow analysis, and a vaporization model for the fuel droplet was adopted to calculate residence time. Finally, a genetic algorithm was adopted to optimize the designs. The combustor and gas generator were optimally designed for 30-tonf, 75-tonf, and 150-tonf engines. The optimized combustors demonstrated superior design characteristics when compared with previous non-optimized results. Wall temperatures at the nozzle throat were optimized to satisfy the requirement of 800 K, and specific impulses were maximized. In addition, the target turbine power and a burned-gas temperature of 1000 K were obtained from the optimized gas-generator design.
A quantum mechanics-based algorithm for vessel segmentation in retinal images
NASA Astrophysics Data System (ADS)
Youssry, Akram; El-Rafei, Ahmed; Elramly, Salwa
2016-03-01
Blood vessel segmentation is an important step in retinal image analysis. It is one of the steps required for computer-aided detection of ophthalmic diseases. In this paper, a novel quantum mechanics-based algorithm for retinal vessel segmentation is presented. The algorithm consists of three major steps. The first step is the preprocessing of the images to prepare the images for further processing. The second step is feature extraction where a set of four features is generated at each image pixel. These features are then combined using a nonlinear transformation for dimensionality reduction. The final step is applying a recently proposed quantum mechanics-based framework for image processing. In this step, pixels are mapped to quantum systems that are allowed to evolve from an initial state to a final state governed by Schrödinger's equation. The evolution is controlled by the Hamiltonian operator which is a function of the extracted features at each pixel. A measurement step is consequently performed to determine whether the pixel belongs to vessel or non-vessel classes. Many functional forms of the Hamiltonian are proposed, and the best performing form was selected. The algorithm is tested on the publicly available DRIVE database. The average results for sensitivity, specificity, and accuracy are 80.29, 97.34, and 95.83 %, respectively. These results are compared to some recently published techniques showing the superior performance of the proposed method. Finally, the implementation of the algorithm on a quantum computer and the challenges facing this implementation are introduced.
A quantum mechanics-based algorithm for vessel segmentation in retinal images
NASA Astrophysics Data System (ADS)
Youssry, Akram; El-Rafei, Ahmed; Elramly, Salwa
2016-06-01
Blood vessel segmentation is an important step in retinal image analysis. It is one of the steps required for computer-aided detection of ophthalmic diseases. In this paper, a novel quantum mechanics-based algorithm for retinal vessel segmentation is presented. The algorithm consists of three major steps. The first step is the preprocessing of the images to prepare the images for further processing. The second step is feature extraction where a set of four features is generated at each image pixel. These features are then combined using a nonlinear transformation for dimensionality reduction. The final step is applying a recently proposed quantum mechanics-based framework for image processing. In this step, pixels are mapped to quantum systems that are allowed to evolve from an initial state to a final state governed by Schrödinger's equation. The evolution is controlled by the Hamiltonian operator which is a function of the extracted features at each pixel. A measurement step is consequently performed to determine whether the pixel belongs to vessel or non-vessel classes. Many functional forms of the Hamiltonian are proposed, and the best performing form was selected. The algorithm is tested on the publicly available DRIVE database. The average results for sensitivity, specificity, and accuracy are 80.29, 97.34, and 95.83 %, respectively. These results are compared to some recently published techniques showing the superior performance of the proposed method. Finally, the implementation of the algorithm on a quantum computer and the challenges facing this implementation are introduced.
Design of a High Resolution Hexapod Positioning Mechanism
NASA Technical Reports Server (NTRS)
Britt, Jamie
2001-01-01
This paper describes the development of a high resolution, six-degree of freedom positioning mechanism. This mechanism, based on the Stewart platform concept, was designed for use with the Developmental Comparative Active Optics Telescope Testbed (DCATT), a ground-based technology testbed for the Next Generation Space Telescope (NGST). The mechanism provides active control to the DCATT telescope's segmented primary mirror. Emphasis is on design decisions and technical challenges. Significant issues include undesirable motion properties of PZT-inchworm actuators, testing difficulties, dimensional stability, and use of advanced composite materials. Supporting test data from prototype mechanisms is presented.
Design of a High Resolution Hexapod Positioning Mechanism
NASA Technical Reports Server (NTRS)
Britt, Jamie; Brodeur, Stephen J. (Technical Monitor)
2001-01-01
This paper describes the development of a high resolution, six-degree of freedom positioning mechanism. This mechanism, based on the Stewart platform concept, was designed for use with the Developmental Comparative Active Optics Telescope Testbed (DCATT), a ground-based technology testbed for the Next Generation Space Telescope (NGST). The mechanism provides active control to the DCATT telescope's segmented primary mirror. Emphasis is on design decisions and technical challenges. Significant issues include undesirable motion properties of PZT-inchworm actuators, testing difficulties, dimensional stability and use of advanced composite materials. Supporting test data from prototype mechanisms is presented.
A new iterative Fourier transform algorithm for optimal design in holographic optical tweezers
NASA Astrophysics Data System (ADS)
Memmolo, P.; Miccio, L.; Merola, F.; Ferraro, P.; Netti, P. A.
2012-06-01
We propose a new Iterative Fourier Transform Algorithm (IFTA) capable to suppress ghost traps and noise in Holographic Optical Tweezers (HOT), maintaining a high diffraction efficiency in a computational time comparable with the others iterative algorithms. The process consists in the planning of the suitable ideal target of optical tweezers as input of classical IFTA and we show we are able to design up to 4 real traps, in the field of view imaged by the microscope objective, using an IFTA built on fictitious phasors, located in strategic positions in the Fourier plane. The effectiveness of the proposed algorithm is evaluated both for numerical and optical reconstructions and compared with the other techniques known in literature.
Springback compensation algorithm for tool design in creep age forming of large aluminum alloy plate
NASA Astrophysics Data System (ADS)
Xu, Xiaolong; Zhan, Lihua; Huang, Minghui
2013-12-01
The creep unified constitutive equations, which was built based on the age forming mechanism of aluminum alloy, was integrated with the commercial finite element analysis software MSC.MARC via the user defined subroutine, CREEP, and the creep age forming process simulations for7055 aluminum alloy plate parts were conducted. Then the springback of the workpiece after forming was calculated by ATOS Professional Software. Based on the combination between simulation results and calculation of springback by ATOS for the formed plate, a new weighted springback compensation algorithm for tool surface modification was developed. The compensate effects between the new algorithm and other overall compensation algorithms on the tool surface are compared. The results show that, the maximal forming error of the workpiece was reduced to below 0.2mm after 5 times compensations with the new weighted algorithm, while error rebound phenomenon occurred and the maximal forming error cannot be reduced to 0.3mm even after 6 times compensations with fixed or variable compensation coefficient, which are based on the overall compensation algorithm.
The multi-disciplinary design study: A life cycle cost algorithm
NASA Technical Reports Server (NTRS)
Harding, R. R.; Pichi, F. J.
1988-01-01
The approach and results of a Life Cycle Cost (LCC) analysis of the Space Station Solar Dynamic Power Subsystem (SDPS) including gimbal pointing and power output performance are documented. The Multi-Discipline Design Tool (MDDT) computer program developed during the 1986 study has been modified to include the design, performance, and cost algorithms for the SDPS as described. As with the Space Station structural and control subsystems, the LCC of the SDPS can be computed within the MDDT program as a function of the engineering design variables. Two simple examples of MDDT's capability to evaluate cost sensitivity and design based on LCC are included. MDDT was designed to accept NASA's IMAT computer program data as input so that IMAT's detailed structural and controls design capability can be assessed with expected system LCC as computed by MDDT. No changes to IMAT were required. Detailed knowledge of IMAT is not required to perform the LCC analyses as the interface with IMAT is noninteractive.
Design of 3D-Printed Titanium Compliant Mechanisms
NASA Technical Reports Server (NTRS)
Merriam, Ezekiel G.; Jones, Jonathan E.; Howell, Larry L.
2014-01-01
This paper describes 3D-printed titanium compliant mechanisms for aerospace applications. It is meant as a primer to help engineers design compliant, multi-axis, printed parts that exhibit high performance. Topics covered include brief introductions to both compliant mechanism design and 3D printing in titanium, material and geometry considerations for 3D printing, modeling techniques, and case studies of both successful and unsuccessful part geometries. Key findings include recommended flexure geometries, minimum thicknesses, and general design guidelines for compliant printed parts that may not be obvious to the first time designer.
Zhu, Wu; Fang, Jian-an; Tang, Yang; Zhang, Wenbing; Du, Wei
2012-01-01
Design of a digital infinite-impulse-response (IIR) filter is the process of synthesizing and implementing a recursive filter network so that a set of prescribed excitations results a set of desired responses. However, the error surface of IIR filters is usually non-linear and multi-modal. In order to find the global minimum indeed, an improved differential evolution (DE) is proposed for digital IIR filter design in this paper. The suggested algorithm is a kind of DE variants with a controllable probabilistic (CPDE) population size. It considers the convergence speed and the computational cost simultaneously by nonperiodic partial increasing or declining individuals according to fitness diversities. In addition, we discuss as well some important aspects for IIR filter design, such as the cost function value, the influence of (noise) perturbations, the convergence rate and successful percentage, the parameter measurement, etc. As to the simulation result, it shows that the presented algorithm is viable and comparable. Compared with six existing State-of-the-Art algorithms-based digital IIR filter design methods obtained by numerical experiments, CPDE is relatively more promising and competitive. PMID:22808191
Design of State-Space-Based Control Algorithms for Wind Turbine Speed Regulation: Preprint
Wright, A.; Balas, M.
2002-01-01
Control can improve the performance of wind turbines by enhancing energy capture and reducing dynamic loads.At the National Renewable Energy Laboratory, we are beginning to design control algorithms for regulation of turbine speed and power using state-space control designs. In this paper, we describe the design of such a control algorithm for regulation of rotor speed in full-load operation (region 3) for a two-bladed wind turbine. We base our control design on simple linear models of a turbine, which contain rotor and generator rotation, drivetrain torsion, and rotor flap degrees of freedom (first mode only). We account for wind-speed fluctuations using disturbance-accommodating control. We show the capability of these control schemes to stabilize the modeled turbine modes via pole placement while using state estimation to reduce the number of turbine measurements that are needed for these control algorithms. We incorporate these controllers into the FAST-AD code and show simulation results for various conditions. Finally, we report conclusions to this work and outline future studies.
Sum-of-squares-based fuzzy controller design using quantum-inspired evolutionary algorithm
NASA Astrophysics Data System (ADS)
Yu, Gwo-Ruey; Huang, Yu-Chia; Cheng, Chih-Yung
2016-07-01
In the field of fuzzy control, control gains are obtained by solving stabilisation conditions in linear-matrix-inequality-based Takagi-Sugeno fuzzy control method and sum-of-squares-based polynomial fuzzy control method. However, the optimal performance requirements are not considered under those stabilisation conditions. In order to handle specific performance problems, this paper proposes a novel design procedure with regard to polynomial fuzzy controllers using quantum-inspired evolutionary algorithms. The first contribution of this paper is a combination of polynomial fuzzy control and quantum-inspired evolutionary algorithms to undertake an optimal performance controller design. The second contribution is the proposed stability condition derived from the polynomial Lyapunov function. The proposed design approach is dissimilar to the traditional approach, in which control gains are obtained by solving the stabilisation conditions. The first step of the controller design uses the quantum-inspired evolutionary algorithms to determine the control gains with the best performance. Then, the stability of the closed-loop system is analysed under the proposed stability conditions. To illustrate effectiveness and validity, the problem of balancing and the up-swing of an inverted pendulum on a cart is used.
Orion Guidance and Control Ascent Abort Algorithm Design and Performance Results
NASA Technical Reports Server (NTRS)
Proud, Ryan W.; Bendle, John R.; Tedesco, Mark B.; Hart, Jeremy J.
2009-01-01
During the ascent flight phase of NASA s Constellation Program, the Ares launch vehicle propels the Orion crew vehicle to an agreed to insertion target. If a failure occurs at any point in time during ascent then a system must be in place to abort the mission and return the crew to a safe landing with a high probability of success. To achieve continuous abort coverage one of two sets of effectors is used. Either the Launch Abort System (LAS), consisting of the Attitude Control Motor (ACM) and the Abort Motor (AM), or the Service Module (SM), consisting of SM Orion Main Engine (OME), Auxiliary (Aux) Jets, and Reaction Control System (RCS) jets, is used. The LAS effectors are used for aborts from liftoff through the first 30 seconds of second stage flight. The SM effectors are used from that point through Main Engine Cutoff (MECO). There are two distinct sets of Guidance and Control (G&C) algorithms that are designed to maximize the performance of these abort effectors. This paper will outline the necessary inputs to the G&C subsystem, the preliminary design of the G&C algorithms, the ability of the algorithms to predict what abort modes are achievable, and the resulting success of the abort system. Abort success will be measured against the Preliminary Design Review (PDR) abort performance metrics and overall performance will be reported. Finally, potential improvements to the G&C design will be discussed.
Optimal fractional delay-IIR filter design using cuckoo search algorithm.
Kumar, Manjeet; Rawat, Tarun Kumar
2015-11-01
This paper applied a novel global meta-heuristic optimization algorithm, cuckoo search algorithm (CSA) to determine optimal coefficients of a fractional delay-infinite impulse response (FD-IIR) filter and trying to meet the ideal frequency response characteristics. Since fractional delay-IIR filter design is a multi-modal optimization problem, it cannot be computed efficiently using conventional gradient based optimization techniques. A weighted least square (WLS) based fitness function is used to improve the performance to a great extent. FD-IIR filters of different orders have been designed using the CSA. The simulation results of the proposed CSA based approach have been compared to those of well accepted evolutionary algorithms like Genetic Algorithm (GA) and Particle Swarm Optimization (PSO). The performance of the CSA based FD-IIR filter is superior to those obtained by GA and PSO. The simulation and statistical results affirm that the proposed approach using CSA outperforms GA and PSO, not only in the convergence rate but also in optimal performance of the designed FD-IIR filter (i.e., smaller magnitude error, smaller phase error, higher percentage improvement in magnitude and phase error, fast convergence rate). The absolute magnitude and phase error obtained for the designed 5th order FD-IIR filter are as low as 0.0037 and 0.0046, respectively. The percentage improvement in magnitude error for CSA based 5th order FD-IIR design with respect to GA and PSO are 80.93% and 74.83% respectively, and phase error are 76.04% and 71.25%, respectively. PMID:26391486
Thermal design of spiral heat exchangers and heat pipes through global best algorithm
NASA Astrophysics Data System (ADS)
Turgut, Oğuz Emrah; Çoban, Mustafa Turhan
2016-07-01
This study deals with global best algorithm based thermal design of spiral heat exchangers and heat pipes. Spiral heat exchangers are devices which are highly efficient in extremely dirty and fouling process duties. Spirals inherent in design maintain high heat transfer coefficients while avoiding hazardous effects of fouling and uneven fluid distribution in the channels. Heat pipes have wide usage in industry. Thanks to the two phase cycle which takes part in operation, they can transfer high amount of heat with a negligible temperature gradient. In this work, a new stochastic based optimization method global best algorithm is applied for multi objective optimization of spiral heat exchangers as well as single objective optimization for heat pipes. Global best algorithm is easy-to-implement, free of derivatives and it can be reliably applied to any optimization problem. Case studies taken from the literature approaches are solved by the proposed algorithm and results obtained from the literature approaches are compared with thosed acquired by GBA. Comparisons reveal that GBA attains better results than literature studies in terms of solution accuracy and efficiency.
Montgomery, Christopher J.; Yang, Chongguan; Parkinson, Alan R.; Chen, J.-Y.
2006-01-01
A genetic optimization algorithm has been applied to the selection of quasi-steady-state (QSS) species in reduced chemical kinetic mechanisms. The algorithm seeks to minimize the error between reduced and detailed chemistry for simple reactor calculations approximating conditions of interest for a computational fluid dynamics simulation. The genetic algorithm does not guarantee that the global optimum will be found, but much greater accuracy can be obtained than by choosing QSS species through a simple kinetic criterion or by human trial and error. The algorithm is demonstrated for methane-air combustion over a range of temperatures and stoichiometries and for homogeneous charge compression ignition engine combustion. The results are in excellent agreement with those predicted by the baseline mechanism. A factor of two reduction in the number of species was obtained for a skeletal mechanism that had already been greatly reduced from the parent detailed mechanism.
Knowledge-based design of complex mechanical systems
Ishii, K.
1988-01-01
The recent development of Artificial Intelligence (AI) techniques allows incorporation of qualitative aspects of design into the computer aids. This thesis presents a framework for applying AI techniques to the design of complex mechanical systems. A complex, yet well-understood design example as a vehicle for the effort is used. The author first reviews how experienced designers use knowledge at various stages of system design. He then proposes a knowledge-based model of the design process and develop frameworks for applying knowledge engineering in order to construct a consultation system for the designers. He proposes four such frameworks for use at different stages of design: (1) Design Compatibility Analysis (DCA) analyzes the compatibility of the designer's design alternatives with the design specification, (2) Initial Design Suggestion (IDS) provides the designer with reasonable initial estimates of the design variables, (3) Rule-based Sensitivity Analysis (RSA) guides the user through redesign, and (4) Active Constraint Deduction (ACD) identifies the bottlenecks of design by heuristic knowledge. These frameworks eliminate unnecessary iterations and allows the user to obtain a satisfactory solution rapidly.
Design and Validation of the Quantum Mechanics Conceptual Survey
ERIC Educational Resources Information Center
McKagan, S. B.; Perkins, K. K.; Wieman, C. E.
2010-01-01
The Quantum Mechanics Conceptual Survey (QMCS) is a 12-question survey of students' conceptual understanding of quantum mechanics. It is intended to be used to measure the relative effectiveness of different instructional methods in modern physics courses. In this paper, we describe the design and validation of the survey, a process that included…
NASA Astrophysics Data System (ADS)
Shen, Xin; Zhang, Jing; Yao, Huang
2015-12-01
Remote sensing satellites play an increasingly prominent role in environmental monitoring and disaster rescue. Taking advantage of almost the same sunshine condition to same place and global coverage, most of these satellites are operated on the sun-synchronous orbit. However, it brings some problems inevitably, the most significant one is that the temporal resolution of sun-synchronous orbit satellite can't satisfy the demand of specific region monitoring mission. To overcome the disadvantages, two methods are exploited: the first one is to build satellite constellation which contains multiple sunsynchronous satellites, just like the CHARTER mechanism has done; the second is to design non-predetermined orbit based on the concrete mission demand. An effective method for remote sensing satellite orbit design based on multiobjective evolution algorithm is presented in this paper. Orbit design problem is converted into a multi-objective optimization problem, and a fast and elitist multi-objective genetic algorithm is utilized to solve this problem. Firstly, the demand of the mission is transformed into multiple objective functions, and the six orbit elements of the satellite are taken as genes in design space, then a simulate evolution process is performed. An optimal resolution can be obtained after specified generation via evolution operation (selection, crossover, and mutation). To examine validity of the proposed method, a case study is introduced: Orbit design of an optical satellite for regional disaster monitoring, the mission demand include both minimizing the average revisit time internal of two objectives. The simulation result shows that the solution for this mission obtained by our method meet the demand the users' demand. We can draw a conclusion that the method presented in this paper is efficient for remote sensing orbit design.
Optimization of high speed pipelining in FPGA-based FIR filter design using genetic algorithm
NASA Astrophysics Data System (ADS)
Meyer-Baese, Uwe; Botella, Guillermo; Romero, David E. T.; Kumm, Martin
2012-06-01
This paper compares FPGA-based full pipelined multiplierless FIR filter design options. Comparison of Distributed Arithmetic (DA), Common Sub-Expression (CSE) sharing and n-dimensional Reduced Adder Graph (RAG-n) multiplierless filter design methods in term of size, speed, and A*T product are provided. Since DA designs are table-based and CSE/RAG-n designs are adder-based, FPGA synthesis design data are used for a realistic comparison. Superior results of a genetic algorithm based optimization of pipeline registers and non-output fundamental coefficients are shown. FIR filters (posted as open source by Kastner et al.) for filters in the length from 6 to 151 coefficients are used.
Multi-Objective Optimal Design of Switch Reluctance Motors Using Adaptive Genetic Algorithm
NASA Astrophysics Data System (ADS)
Rashidi, Mehran; Rashidi, Farzan
In this paper a design methodology based on multi objective genetic algorithm (MOGA) is presented to design the switched reluctance motors with multiple conflicting objectives such as efficiency, power factor, full load torque, and full load current, specified dimension, weight of cooper and iron and also manufacturing cost. The optimally designed motor is compared with an industrial motor having the same ratings. Results verify that the proposed method gives better performance for the multi-objective optimization problems. The results of optimal design show the reduction in the specified dimension, weight and manufacturing cost, and the improvement in the power factor, full load torque, and efficiency of the motor.A major advantage of the method is its quite short response time in obtaining the optimal design.
NASA Astrophysics Data System (ADS)
Sciandra, Vincent
performance of the algorithm generated sectors to the current sectors for a variety of configurations and scenarios, and comparing these results to those of the current sectors. The effect of dynamic airspace configurations will then be tested by observing the effects of update rate on the algorithm generated sector results. Finally, the algorithm will be used with simulated data, whose evaluation would show the ability of the sector design algorithm to meet the objectives of the NextGen system. Upon validation, the algorithm may be successfully incorporated into a larger Terminal Flow Algorithm, developed by our partners at Mosaic ATM, as the final step in the TDAC process.
Design And Implementation Of A Multi-Sensor Fusion Algorithm On A Hypercube Computer Architecture
NASA Astrophysics Data System (ADS)
Glover, Charles W.
1990-03-01
was obtained. This paper will also discuss the design of a completely parallel MSI algorithm.
Schalkoff, R.J.; Shaaban, K.M.; Carver, A.E.
1996-12-31
The ARIES {number_sign}1 (Autonomous Robotic Inspection Experimental System) vision system is used to acquire drum surface images under controlled conditions and subsequently perform autonomous visual inspection leading to a classification as `acceptable` or `suspect`. Specific topics described include vision system design methodology, algorithmic structure,hardware processing structure, and image acquisition hardware. Most of these capabilities were demonstrated at the ARIES Phase II Demo held on Nov. 30, 1995. Finally, Phase III efforts are briefly addressed.
Mechanical design of NASA Ames Research Center vertical motion simulator
NASA Technical Reports Server (NTRS)
Engelbert, D. F.; Bakke, A. P.; Chargin, M. K.; Vallotton, W. C.
1976-01-01
NASA has designed and is constructing a new flight simulator with large vertical travel. Several aspects of the mechanical design of this Vertical Motion Simulator (VMS) are discussed, including the multiple rack and pinion vertical drive, a pneumatic equilibration system, and the friction-damped rigid link catenaries used as cable supports.
Design and verification of mechanisms for a large foldable antenna
NASA Technical Reports Server (NTRS)
Luhmann, Hans Jurgen; Etzler, Carl Christian; Wagner, Rudolf
1989-01-01
The characteristics of the Synthetic Aperture Radar (SAR) antenna aboard the ESA Remote Sensing Satellite (ERS-1) are presented. The antenna is folded into a dense package for launch and is deployed in orbit. The design requirements and constraints, their impact on the design, and the resulting features of the mechanisms are discussed.
Wang, Yuping; Feng, Junhong
2013-01-01
In association rule mining, evaluating an association rule needs to repeatedly scan database to compare the whole database with the antecedent, consequent of a rule and the whole rule. In order to decrease the number of comparisons and time consuming, we present an attribute index strategy. It only needs to scan database once to create the attribute index of each attribute. Then all metrics values to evaluate an association rule do not need to scan database any further, but acquire data only by means of the attribute indices. The paper visualizes association rule mining as a multiobjective problem rather than a single objective one. In order to make the acquired solutions scatter uniformly toward the Pareto frontier in the objective space, elitism policy and uniform design are introduced. The paper presents the algorithm of attribute index and uniform design based multiobjective association rule mining with evolutionary algorithm, abbreviated as IUARMMEA. It does not require the user-specified minimum support and minimum confidence anymore, but uses a simple attribute index. It uses a well-designed real encoding so as to extend its application scope. Experiments performed on several databases demonstrate that the proposed algorithm has excellent performance, and it can significantly reduce the number of comparisons and time consumption. PMID:23766683
NASA Astrophysics Data System (ADS)
Ushijima, Timothy T.; Yeh, William W.-G.
2013-10-01
An optimal experimental design algorithm is developed to select locations for a network of observation wells that provide maximum information about unknown groundwater pumping in a confined, anisotropic aquifer. The design uses a maximal information criterion that chooses, among competing designs, the design that maximizes the sum of squared sensitivities while conforming to specified design constraints. The formulated optimization problem is non-convex and contains integer variables necessitating a combinatorial search. Given a realistic large-scale model, the size of the combinatorial search required can make the problem difficult, if not impossible, to solve using traditional mathematical programming techniques. Genetic algorithms (GAs) can be used to perform the global search; however, because a GA requires a large number of calls to a groundwater model, the formulated optimization problem still may be infeasible to solve. As a result, proper orthogonal decomposition (POD) is applied to the groundwater model to reduce its dimensionality. Then, the information matrix in the full model space can be searched without solving the full model. Results from a small-scale test case show identical optimal solutions among the GA, integer programming, and exhaustive search methods. This demonstrates the GA's ability to determine the optimal solution. In addition, the results show that a GA with POD model reduction is several orders of magnitude faster in finding the optimal solution than a GA using the full model. The proposed experimental design algorithm is applied to a realistic, two-dimensional, large-scale groundwater problem. The GA converged to a solution for this large-scale problem.
Process Improvement Through Tool Integration in Aero-Mechanical Design
NASA Technical Reports Server (NTRS)
Briggs, Clark
2010-01-01
Emerging capabilities in commercial design tools promise to significantly improve the multi-disciplinary and inter-disciplinary design and analysis coverage for aerospace mechanical engineers. This paper explores the analysis process for two example problems of a wing and flap mechanical drive system and an aircraft landing gear door panel. The examples begin with the design solid models and include various analysis disciplines such as structural stress and aerodynamic loads. Analytical methods include CFD, multi-body dynamics with flexible bodies and structural analysis. Elements of analysis data management, data visualization and collaboration are also included.
Design tool for multiprocessor scheduling and evaluation of iterative dataflow algorithms
NASA Technical Reports Server (NTRS)
Jones, Robert L., III
1995-01-01
A graph-theoretic design process and software tool is defined for selecting a multiprocessing scheduling solution for a class of computational problems. The problems of interest are those that can be described with a dataflow graph and are intended to be executed repetitively on a set of identical processors. Typical applications include signal processing and control law problems. Graph-search algorithms and analysis techniques are introduced and shown to effectively determine performance bounds, scheduling constraints, and resource requirements. The software tool applies the design process to a given problem and includes performance optimization through the inclusion of additional precedence constraints among the schedulable tasks.
An algorithm to design finite field multipliers using a self-dual normal basis
NASA Technical Reports Server (NTRS)
Wang, Charles C.
1989-01-01
The concept of using a self-dual normal basis to design the Massey-Omura finite-field multiplier is presented. An algorithm is given to locate a self-dual normal basis for GF(2m) for odd m. A method to construct the product function for designing the Massey-Omura multiplier is developed. It is shown that the construction of the product function based on a self-dual basis is simpler than that based on an arbitrary normal basis.
Optical and mechanical design advantages using polymer optics
NASA Astrophysics Data System (ADS)
Doushkina, Valentina; Fleming, Erik
2009-08-01
Precision diamond-turned or molded polymer optics are utilized in a wide range of commercial markets and applications including; medical disposables, bar code scan/recognition, security and fingerprint scanners, motion and presence sensors, CCD cameras, laser collimation and others.. The use of polymer optics was previously relegated to less technically challenging applications. Current advancements in polymer technology and injection molding capabilities have increased the manufacturability and precision of polymer optics. Polymer materials with optical properties are being thrust to the design forefront for new, sophisticated electro-optical applications. Designing and manufacturing optics and optical systems using polymers alone or hybrid polymer/glass applications provides complete custom capability and offers new optical and opto-mechanical solutions for a variety of optical and opto-mechanical modules, assemblies and components. Integrated mounting offers configuration flexibility, considerable design freedom, simplified optical alignment, mechanical design, assembly and packaging. The system is assembled, aligned, optically spaced, and sealed in a single manufacturing step.
Direction-of-arrival interferometer array design using genetic algorithm with fuzzy logic
NASA Astrophysics Data System (ADS)
Straatveit, S. Nils
2004-04-01
Design of interferometer arrays for radio frequency direction of arrival estimation involves optimizing conflicting requirements. For example, high resolution conflicts with low cost. Lower level requirements also invoke lower level design issues such as ambiguity in direction of arrival angle. A more efficient array design process is described here, which uses a genetic algorithm with a growing genome and fuzzy logic scoring. Extensive simulation software is also needed. Simulation starts with randomized small array configurations. These are then evaluated against the fitness functions with results scored using fuzzy logic. The best-fit of the population are combined to produce the next generation. A mutation function introduces slight randomness in some genomes. Finally, if the overall population scores well the size of the genome is increased until final genome size is consistent with the desired array resolution requirement. The genetic algorithm design process described here produced a number of array designs. The results indicate discrete stages or steps in the optimization and an interesting trade-off of lower resolution for greater accuracy.
Bieniawski, Z.T.
1996-04-01
A good designer needs not only knowledge for designing (technical know-how that is used to generate alternative design solutions) but also must have knowledge about designing (appropriate principles and systematic methodology to follow). Concepts such as {open_quotes}design for manufacture{close_quotes} or {open_quotes}concurrent engineering{close_quotes} are widely used in the industry. In the field of rock engineering, only limited attention has been paid to the design process because design of structures in rock masses presents unique challenges to the designers as a result of the uncertainties inherent in characterization of geologic media. However, a stage has now been reached where we are be able to sufficiently characterize rock masses for engineering purposes and identify the rock mechanics issues involved but are still lacking engineering design principles and methodology to maximize our design performance. This paper discusses the principles and methodology of the engineering design process directed to integrating site characterization activities with design, construction and performance of an underground repository. Using the latest information from the Yucca Mountain Project on geology, rock mechanics and starter tunnel design, the current lack of integration is pointed out and it is shown how rock mechanics issues can be effectively interwoven with repository design through a systematic design process methodology leading to improved repository performance. In essence, the design process is seen as the use of design principles within an integrating design methodology, leading to innovative problem solving. In particular, a new concept of {open_quotes}Design for Constructibility and Performance{close_quotes} is introduced. This is discussed with respect to ten rock mechanics issues identified for repository design and performance.
Designing an Algorithm to Preserve Privacy for Medical Record Linkage With Error-Prone Data
Pal, Doyel; Chen, Tingting; Khethavath, Praveen
2014-01-01
Background Linking medical records across different medical service providers is important to the enhancement of health care quality and public health surveillance. In records linkage, protecting the patients’ privacy is a primary requirement. In real-world health care databases, records may well contain errors due to various reasons such as typos. Linking the error-prone data and preserving data privacy at the same time are very difficult. Existing privacy preserving solutions for this problem are only restricted to textual data. Objective To enable different medical service providers to link their error-prone data in a private way, our aim was to provide a holistic solution by designing and developing a medical record linkage system for medical service providers. Methods To initiate a record linkage, one provider selects one of its collaborators in the Connection Management Module, chooses some attributes of the database to be matched, and establishes the connection with the collaborator after the negotiation. In the Data Matching Module, for error-free data, our solution offered two different choices for cryptographic schemes. For error-prone numerical data, we proposed a newly designed privacy preserving linking algorithm named the Error-Tolerant Linking Algorithm, that allows the error-prone data to be correctly matched if the distance between the two records is below a threshold. Results We designed and developed a comprehensive and user-friendly software system that provides privacy preserving record linkage functions for medical service providers, which meets the regulation of Health Insurance Portability and Accountability Act. It does not require a third party and it is secure in that neither entity can learn the records in the other’s database. Moreover, our novel Error-Tolerant Linking Algorithm implemented in this software can work well with error-prone numerical data. We theoretically proved the correctness and security of our Error
Voigt, C A; Gordon, D B; Mayo, S L
2000-06-01
Finding the minimum energy amino acid side-chain conformation is a fundamental problem in both homology modeling and protein design. To address this issue, numerous computational algorithms have been proposed. However, there have been few quantitative comparisons between methods and there is very little general understanding of the types of problems that are appropriate for each algorithm. Here, we study four common search techniques: Monte Carlo (MC) and Monte Carlo plus quench (MCQ); genetic algorithms (GA); self-consistent mean field (SCMF); and dead-end elimination (DEE). Both SCMF and DEE are deterministic, and if DEE converges, it is guaranteed that its solution is the global minimum energy conformation (GMEC). This provides a means to compare the accuracy of SCMF and the stochastic methods. For the side-chain placement calculations, we find that DEE rapidly converges to the GMEC in all the test cases. The other algorithms converge on significantly incorrect solutions; the average fraction of incorrect rotamers for SCMF is 0.12, GA 0.09, and MCQ 0.05. For the protein design calculations, design positions are progressively added to the side-chain placement calculation until the time required for DEE diverges sharply. As the complexity of the problem increases, the accuracy of each method is determined so that the results can be extrapolated into the region where DEE is no longer tractable. We find that both SCMF and MCQ perform reasonably well on core calculations (fraction amino acids incorrect is SCMF 0.07, MCQ 0.04), but fail considerably on the boundary (SCMF 0.28, MCQ 0.32) and surface calculations (SCMF 0.37, MCQ 0.44). PMID:10835284
Watanabe, Shin; Takamatsu, Atsuko
2014-01-01
In this paper, we propose designing transportation network topology and traffic distribution under fluctuating conditions using a bio-inspired algorithm. The algorithm is inspired by the adaptive behavior observed in an amoeba-like organism, plasmodial slime mold, more formally known as plasmodium of Physarum plycephalum. This organism forms a transportation network to distribute its protoplasm, the fluidic contents of its cell, throughout its large cell body. In this process, the diameter of the transportation tubes adapts to the flux of the protoplasm. The Physarum algorithm, which mimics this adaptive behavior, has been widely applied to complex problems, such as maze solving and designing the topology of railroad grids, under static conditions. However, in most situations, environmental conditions fluctuate; for example, in power grids, the consumption of electric power shows daily, weekly, and annual periodicity depending on the lifestyles or the business needs of the individual consumers. This paper studies the design of network topology and traffic distribution with oscillatory input and output traffic flows. The network topology proposed by the Physarum algorithm is controlled by a parameter of the adaptation process of the tubes. We observe various rich topologies such as complete mesh, partial mesh, Y-shaped, and V-shaped networks depending on this adaptation parameter and evaluate them on the basis of three performance functions: loss, cost, and vulnerability. Our results indicate that consideration of the oscillatory conditions and the phase-lags in the multiple outputs of the network is important: The building and/or maintenance cost of the network can be reduced by introducing the oscillating condition, and when the phase-lag among the outputs is large, the transportation loss can also be reduced. We use stability analysis to reveal how the system exhibits various topologies depending on the parameter. PMID:24586616
NASA Astrophysics Data System (ADS)
Raghavan, Ajay; Saha, Bhaskar
2013-03-01
Photo enforcement devices for traffic rules such as red lights, toll, stops, and speed limits are increasingly being deployed in cities and counties around the world to ensure smooth traffic flow and public safety. These are typically unattended fielded systems, and so it is important to periodically check them for potential image/video quality problems that might interfere with their intended functionality. There is interest in automating such checks to reduce the operational overhead and human error involved in manually checking large camera device fleets. Examples of problems affecting such camera devices include exposure issues, focus drifts, obstructions, misalignment, download errors, and motion blur. Furthermore, in some cases, in addition to the sub-algorithms for individual problems, one also has to carefully design the overall algorithm and logic to check for and accurately classifying these individual problems. Some of these issues can occur in tandem or have the potential to be confused for each other by automated algorithms. Examples include camera misalignment that can cause some scene elements to go out of focus for wide-area scenes or download errors that can be misinterpreted as an obstruction. Therefore, the sequence in which the sub-algorithms are utilized is also important. This paper presents an overview of these problems along with no-reference and reduced reference image and video quality solutions to detect and classify such faults.
NASA Technical Reports Server (NTRS)
Ng, Hok K.; Grabbe, Shon; Mukherjee, Avijit
2010-01-01
The optimization of traffic flows in congested airspace with varying convective weather is a challenging problem. One approach is to generate shortest routes between origins and destinations while meeting airspace capacity constraint in the presence of uncertainties, such as weather and airspace demand. This study focuses on development of an optimal flight path search algorithm that optimizes national airspace system throughput and efficiency in the presence of uncertainties. The algorithm is based on dynamic programming and utilizes the predicted probability that an aircraft will deviate around convective weather. It is shown that the running time of the algorithm increases linearly with the total number of links between all stages. The optimal routes minimize a combination of fuel cost and expected cost of route deviation due to convective weather. They are considered as alternatives to the set of coded departure routes which are predefined by FAA to reroute pre-departure flights around weather or air traffic constraints. A formula, which calculates predicted probability of deviation from a given flight path, is also derived. The predicted probability of deviation is calculated for all path candidates. Routes with the best probability are selected as optimal. The predicted probability of deviation serves as a computable measure of reliability in pre-departure rerouting. The algorithm can also be extended to automatically adjust its design parameters to satisfy the desired level of reliability.
Algorithm architecture co-design for ultra low-power image sensor
NASA Astrophysics Data System (ADS)
Laforest, T.; Dupret, A.; Verdant, A.; Lattard, D.; Villard, P.
2012-03-01
In a context of embedded video surveillance, stand alone leftbehind image sensors are used to detect events with high level of confidence, but also with a very low power consumption. Using a steady camera, motion detection algorithms based on background estimation to find regions in movement are simple to implement and computationally efficient. To reduce power consumption, the background is estimated using a down sampled image formed of macropixels. In order to extend the class of moving objects to be detected, we propose an original mixed mode architecture developed thanks to an algorithm architecture co-design methodology. This programmable architecture is composed of a vector of SIMD processors. A basic RISC architecture was optimized in order to implement motion detection algorithms with a dedicated set of 42 instructions. Definition of delta modulation as a calculation primitive has allowed to implement algorithms in a very compact way. Thereby, a 1920x1080@25fps CMOS image sensor performing integrated motion detection is proposed with a power estimation of 1.8 mW.
Design and simulation of imaging algorithm for Fresnel telescopy imaging system
NASA Astrophysics Data System (ADS)
Lv, Xiao-yu; Liu, Li-ren; Yan, Ai-min; Sun, Jian-feng; Dai, En-wen; Li, Bing
2011-06-01
Fresnel telescopy (short for Fresnel telescopy full-aperture synthesized imaging ladar) is a new high resolution active laser imaging technique. This technique is a variant of Fourier telescopy and optical scanning holography, which uses Fresnel zone plates to scan target. Compare with synthetic aperture imaging ladar(SAIL), Fresnel telescopy avoids problem of time synchronization and space synchronization, which decreasing technical difficulty. In one-dimensional (1D) scanning operational mode for moving target, after time-to-space transformation, spatial distribution of sampling data is non-uniform because of the relative motion between target and scanning beam. However, as we use fast Fourier transform (FFT) in the following imaging algorithm of matched filtering, distribution of data should be regular and uniform. We use resampling interpolation to transform the data into two-dimensional (2D) uniform distribution, and accuracy of resampling interpolation process mainly affects the reconstruction results. Imaging algorithms with different resampling interpolation algorithms have been analysis and computer simulation are also given. We get good reconstruction results of the target, which proves that the designed imaging algorithm for Fresnel telescopy imaging system is effective. This work is found to have substantial practical value and offers significant benefit for high resolution imaging system of Fresnel telescopy laser imaging ladar.
The design and hardware implementation of a low-power real-time seizure detection algorithm
NASA Astrophysics Data System (ADS)
Raghunathan, Shriram; Gupta, Sumeet K.; Ward, Matthew P.; Worth, Robert M.; Roy, Kaushik; Irazoqui, Pedro P.
2009-10-01
Epilepsy affects more than 1% of the world's population. Responsive neurostimulation is emerging as an alternative therapy for the 30% of the epileptic patient population that does not benefit from pharmacological treatment. Efficient seizure detection algorithms will enable closed-loop epilepsy prostheses by stimulating the epileptogenic focus within an early onset window. Critically, this is expected to reduce neuronal desensitization over time and lead to longer-term device efficacy. This work presents a novel event-based seizure detection algorithm along with a low-power digital circuit implementation. Hippocampal depth-electrode recordings from six kainate-treated rats are used to validate the algorithm and hardware performance in this preliminary study. The design process illustrates crucial trade-offs in translating mathematical models into hardware implementations and validates statistical optimizations made with empirical data analyses on results obtained using a real-time functioning hardware prototype. Using quantitatively predicted thresholds from the depth-electrode recordings, the auto-updating algorithm performs with an average sensitivity and selectivity of 95.3 ± 0.02% and 88.9 ± 0.01% (mean ± SEα = 0.05), respectively, on untrained data with a detection delay of 8.5 s [5.97, 11.04] from electrographic onset. The hardware implementation is shown feasible using CMOS circuits consuming under 350 nW of power from a 250 mV supply voltage from simulations on the MIT 180 nm SOI process.
Design of aspherical surfaces for panoramic imagers using multi-populations genetic algorithm
NASA Astrophysics Data System (ADS)
Wang, Li-Ping; Liang, Zhong-zhu; Jin, Chun-Shui
2009-05-01
A design method of aspherical surface for panoramic imaging system with two mirrors using multi-populations genetic algorithms is proposed. Astigmatism induced by mirrors may significantly compromise image resolution. To solve this problem, we induced algebraic expression of astigmatism in panoramic imager based on generalized Coddington equation and theory of geometric optics. Then, we propose an optimization process for mirror profile design to eliminate astigmatism and provide purposely-designed projection formula with aid of MPGA. A series of polynomial expressions of aspherical surfaces are obtained and procedures of the design are presented. In order to facilitate ray tracing and aberration calculation, even asphere surface model is obtained by using of hybrid schemes combining MPGA and damped least squares. Finally, a prototype of the catadioptric panoramic imager has been developed and panoramic ring image is obtained.
An algorithm to design finite field multipliers using a self-dual normal basis
NASA Technical Reports Server (NTRS)
Wang, C. C.
1987-01-01
Finite field multiplication is central in the implementation of some error-correcting coders. Massey and Omura have presented a revolutionary design for multiplication in a finite field. In their design, a normal base is utilized to represent the elements of the field. The concept of using a self-dual normal basis to design the Massey-Omura finite field multiplier is presented. Presented first is an algorithm to locate a self-dual normal basis for GF(2 sup m) for odd m. Then a method to construct the product function for designing the Massey-Omura multiplier is developed. It is shown that the construction of the product function base on a self-dual basis is simpler than that based on an arbitrary normal base.
Genetic algorithm based design optimization of a permanent magnet brushless dc motor
NASA Astrophysics Data System (ADS)
Upadhyay, P. R.; Rajagopal, K. R.
2005-05-01
Genetic algorithm (GA) based design optimization of a permanent magnet brushless dc motor is presented in this paper. A 70 W, 350 rpm, ceiling fan motor with radial-filed configuration is designed by considering the efficiency as the objective function. Temperature-rise and motor weight are the constraints and the slot electric loading, magnet-fraction, slot-fraction, airgap, and airgap flux density are the design variables. The efficiency and the phase-inductance of the motor designed using the developed CAD program are improved by using the GA based optimization technique; from 84.75% and 5.55 mH to 86.06% and 2.4 mH, respectively.
An Optimal Design Methodology of Tapered Roller Bearings Using Genetic Algorithms
NASA Astrophysics Data System (ADS)
Tiwari, Rajiv; Sunil, Kumar K.; Reddy, R. S.
2012-03-01
In the design of tapered roller bearings, long life is the one of the most important criterion. The design of bearings has to satisfy constraints of geometry and strength, while operating at its rated speed. An optimal design methodology is needed to achieve this objective (i.e., the maximization of the fatigue life). The fatigue life is directly proportional to the dynamic capacity; hence, for the present case, the latter has been chosen as the objective function. It has been optimized by using a constrained nonlinear formulation with real-coded genetic algorithms. Design variables for the bearing include four geometrical parameters: the bearing pitch diameter, the diameter of the roller, the effective length of the roller, and the number of rollers. These directly affect the dynamic capacity of tapered roller bearings. In addition to these, another five design constraint constants are included, which indirectly affect the basic dynamic capacity of tapered roller bearings. The five design constraint constants have been given bounds based on the parametric studies through initial optimization runs. There is good agreement between the optimized and standard bearings in respect to the basic dynamic capacity. A convergence study has been carried out to ensure the global optimum point in the design. A sensitivity analysis of various design parameters, using the Monte Carlo simulation method, has been performed to see changes in the dynamic capacity. Illustrations show that none of the geometric design parameters have adverse affect on the dynamic capacity.
Mechanical design of a high field common coil magnet
Caspi, S.; Chow, K.; Dietderich, D.; Gourlay, S.; Gupta, R.; McInturff, A.; Millos, G.; Scanlan, R.
1999-03-18
A common coil design for high field 2-in-1 accelerator magnets has been previously presented as a 'conductor-friendly' option for high field magnets applicable for a Very Large Hadron Collider. This paper presents the mechanical design for a 14 tesla 2-in-1 dipole based on the common coil design approach. The magnet will use a high current density Nb{sub 3}Sn conductor. The design addresses mechanical issues particular to the common coil geometry: horizontal support against coil edges, vertical preload on coil faces, end loading and support, and coil stresses and strains. The magnet is the second in a series of racetrack coil magnets that will provide experimental verification of the common coil design approach.
Chen, Tinggui; Xiao, Renbin
2014-01-01
Due to fierce market competition, how to improve product quality and reduce development cost determines the core competitiveness of enterprises. However, design iteration generally causes increases of product cost and delays of development time as well, so how to identify and model couplings among tasks in product design and development has become an important issue for enterprises to settle. In this paper, the shortcomings existing in WTM model are discussed and tearing approach as well as inner iteration method is used to complement the classic WTM model. In addition, the ABC algorithm is also introduced to find out the optimal decoupling schemes. In this paper, firstly, tearing approach and inner iteration method are analyzed for solving coupled sets. Secondly, a hybrid iteration model combining these two technologies is set up. Thirdly, a high-performance swarm intelligence algorithm, artificial bee colony, is adopted to realize problem-solving. Finally, an engineering design of a chemical processing system is given in order to verify its reasonability and effectiveness. PMID:25431584
2014-01-01
Due to fierce market competition, how to improve product quality and reduce development cost determines the core competitiveness of enterprises. However, design iteration generally causes increases of product cost and delays of development time as well, so how to identify and model couplings among tasks in product design and development has become an important issue for enterprises to settle. In this paper, the shortcomings existing in WTM model are discussed and tearing approach as well as inner iteration method is used to complement the classic WTM model. In addition, the ABC algorithm is also introduced to find out the optimal decoupling schemes. In this paper, firstly, tearing approach and inner iteration method are analyzed for solving coupled sets. Secondly, a hybrid iteration model combining these two technologies is set up. Thirdly, a high-performance swarm intelligence algorithm, artificial bee colony, is adopted to realize problem-solving. Finally, an engineering design of a chemical processing system is given in order to verify its reasonability and effectiveness. PMID:25431584
A High Precision Position Sensor Design and Its Signal Processing Algorithm for a Maglev Train
Xue, Song; Long, Zhiqiang; He, Ning; Chang, Wensen
2012-01-01
High precision positioning technology for a kind of high speed maglev train with an electromagnetic suspension (EMS) system is studied. At first, the basic structure and functions of the position sensor are introduced and some key techniques to enhance the positioning precision are designed. Then, in order to further improve the positioning signal quality and the fault-tolerant ability of the sensor, a new kind of discrete-time tracking differentiator (TD) is proposed based on nonlinear optimal control theory. This new TD has good filtering and differentiating performances and a small calculation load. It is suitable for real-time signal processing. The stability, convergence property and frequency characteristics of the TD are studied and analyzed thoroughly. The delay constant of the TD is figured out and an effective time delay compensation algorithm is proposed. Based on the TD technology, a filtering process is introduced in to improve the positioning signal waveform when the sensor is under bad working conditions, and a two-sensor switching algorithm is designed to eliminate the positioning errors caused by the joint gaps of the long stator. The effectiveness and stability of the sensor and its signal processing algorithms are proved by the experiments on a test train during a long-term test run. PMID:22778582
A high precision position sensor design and its signal processing algorithm for a maglev train.
Xue, Song; Long, Zhiqiang; He, Ning; Chang, Wensen
2012-01-01
High precision positioning technology for a kind of high speed maglev train with an electromagnetic suspension (EMS) system is studied. At first, the basic structure and functions of the position sensor are introduced and some key techniques to enhance the positioning precision are designed. Then, in order to further improve the positioning signal quality and the fault-tolerant ability of the sensor, a new kind of discrete-time tracking differentiator (TD) is proposed based on nonlinear optimal control theory. This new TD has good filtering and differentiating performances and a small calculation load. It is suitable for real-time signal processing. The stability, convergence property and frequency characteristics of the TD are studied and analyzed thoroughly. The delay constant of the TD is figured out and an effective time delay compensation algorithm is proposed. Based on the TD technology, a filtering process is introduced in to improve the positioning signal waveform when the sensor is under bad working conditions, and a two-sensor switching algorithm is designed to eliminate the positioning errors caused by the joint gaps of the long stator. The effectiveness and stability of the sensor and its signal processing algorithms are proved by the experiments on a test train during a long-term test run. PMID:22778582
A Genetic Algorithm for the Bi-Level Topological Design of Local Area Networks
Camacho-Vallejo, José-Fernando; Mar-Ortiz, Julio; López-Ramos, Francisco; Rodríguez, Ricardo Pedraza
2015-01-01
Local access networks (LAN) are commonly used as communication infrastructures which meet the demand of a set of users in the local environment. Usually these networks consist of several LAN segments connected by bridges. The topological LAN design bi-level problem consists on assigning users to clusters and the union of clusters by bridges in order to obtain a minimum response time network with minimum connection cost. Therefore, the decision of optimally assigning users to clusters will be made by the leader and the follower will make the decision of connecting all the clusters while forming a spanning tree. In this paper, we propose a genetic algorithm for solving the bi-level topological design of a Local Access Network. Our solution method considers the Stackelberg equilibrium to solve the bi-level problem. The Stackelberg-Genetic algorithm procedure deals with the fact that the follower’s problem cannot be optimally solved in a straightforward manner. The computational results obtained from two different sets of instances show that the performance of the developed algorithm is efficient and that it is more suitable for solving the bi-level problem than a previous Nash-Genetic approach. PMID:26102502
SNL Mechanical Computer Aided Design (MCAD) guide 2007.
Moore, Brandon; Pollice, Stephanie L.; Martinez, Jack R.
2007-12-01
This document is considered a mechanical design best-practice guide to new and experienced designers alike. The contents consist of topics related to using Computer Aided Design (CAD) software, performing basic analyses, and using configuration management. The details specific to a particular topic have been leveraged against existing Product Realization Standard (PRS) and Technical Business Practice (TBP) requirements while maintaining alignment with sound engineering and design practices. This document is to be considered dynamic in that subsequent updates will be reflected in the main title, and each update will be published on an annual basis.
A guided search genetic algorithm using mined rules for optimal affective product design
NASA Astrophysics Data System (ADS)
Fung, Chris K. Y.; Kwong, C. K.; Chan, Kit Yan; Jiang, H.
2014-08-01
Affective design is an important aspect of new product development, especially for consumer products, to achieve a competitive edge in the marketplace. It can help companies to develop new products that can better satisfy the emotional needs of customers. However, product designers usually encounter difficulties in determining the optimal settings of the design attributes for affective design. In this article, a novel guided search genetic algorithm (GA) approach is proposed to determine the optimal design attribute settings for affective design. The optimization model formulated based on the proposed approach applied constraints and guided search operators, which were formulated based on mined rules, to guide the GA search and to achieve desirable solutions. A case study on the affective design of mobile phones was conducted to illustrate the proposed approach and validate its effectiveness. Validation tests were conducted, and the results show that the guided search GA approach outperforms the GA approach without the guided search strategy in terms of GA convergence and computational time. In addition, the guided search optimization model is capable of improving GA to generate good solutions for affective design.
Binary particle swarm optimization algorithm assisted to design of plasmonic nanospheres sensor
NASA Astrophysics Data System (ADS)
Kaboli, Milad; Akhlaghi, Majid; Shahmirzaee, Hossein
2016-04-01
In this study, a coherent perfect absorption (CPA)-type sensor based on plasmonic nanoparticles is proposed. It consists of a plasmonic nanospheres array on top of a quartz substrate. The refractive index changes above the sensor surface, which is due to the appearance of gas or the absorption of biomolecules, can be detected by measuring the resulting spectral shifts of the absorption coefficient. Since the CPA efficiency depends strongly on the number of plasmonic nanoparticles and the locations of nanoparticles, binary particle swarm optimization (BPSO) algorithm is used to design an optimized array of the plasmonic nanospheres. This optimized structure should be maximizing the absorption coefficient only in the one frequency. BPSO algorithm, a swarm of birds including a matrix with binary entries responsible for controlling nanospheres in the array, shows the presence with symbol of ('1') and the absence with ('0'). The sensor can be used for sensing both gas and low refractive index materials in an aqueous environment.
Low PMEPR OFDM Radar Waveform Design Using the Iterative Least Squares Algorithm
NASA Astrophysics Data System (ADS)
Huang, Tianyao; Zhao, Tong
2015-11-01
This letter considers waveform design of orthogonal frequency division multiplexing (OFDM) signal for radar applications, and aims at mitigating the envelope fluctuation in OFDM. A novel method is proposed to reduce the peak-to-mean envelope power ratio (PMEPR), which is commonly used to evaluate the fluctuation. The proposed method is based on the tone reservation approach, in which some bits or subcarriers of OFDM are allocated for decreasing PMEPR. We introduce the coefficient of variation of envelopes (CVE) as the cost function for waveform optimization, and develop an iterative least squares algorithm. Minimizing CVE leads to distinct PMEPR reduction, and it is guaranteed that the cost function monotonically decreases by applying the iterative algorithm. Simulations demonstrate that the envelope is significantly smoothed by the proposed method.
Morita, Kenji; Jitsev, Jenia; Morrison, Abigail
2016-09-15
Value-based action selection has been suggested to be realized in the corticostriatal local circuits through competition among neural populations. In this article, we review theoretical and experimental studies that have constructed and verified this notion, and provide new perspectives on how the local-circuit selection mechanisms implement reinforcement learning (RL) algorithms and computations beyond them. The striatal neurons are mostly inhibitory, and lateral inhibition among them has been classically proposed to realize "Winner-Take-All (WTA)" selection of the maximum-valued action (i.e., 'max' operation). Although this view has been challenged by the revealed weakness, sparseness, and asymmetry of lateral inhibition, which suggest more complex dynamics, WTA-like competition could still occur on short time scales. Unlike the striatal circuit, the cortical circuit contains recurrent excitation, which may enable retention or temporal integration of information and probabilistic "soft-max" selection. The striatal "max" circuit and the cortical "soft-max" circuit might co-implement an RL algorithm called Q-learning; the cortical circuit might also similarly serve for other algorithms such as SARSA. In these implementations, the cortical circuit presumably sustains activity representing the executed action, which negatively impacts dopamine neurons so that they can calculate reward-prediction-error. Regarding the suggested more complex dynamics of striatal, as well as cortical, circuits on long time scales, which could be viewed as a sequence of short WTA fragments, computational roles remain open: such a sequence might represent (1) sequential state-action-state transitions, constituting replay or simulation of the internal model, (2) a single state/action by the whole trajectory, or (3) probabilistic sampling of state/action. PMID:27173430
Mechanics of intraply hybrid composites - Properties, analysis and design
NASA Technical Reports Server (NTRS)
Chamis, C. C.; Sinclair, J. H.
1979-01-01
A mechanics theory is developed for predicting the physical thermal, hygral and mechanical properties (including various strengths) of unidirectional intraply hybrid composites (UIHC) based on unidirectional properties of the constituent composites. Procedures are described which can use this theory in conjunction with composite mechanics computer codes and general purpose structural analysis finite element programs for the analysis/design of structural components made from intraply hybrid angleplied laminates (IHAL). Comparisons with limited data show that this theory predicts mechanical properties of UIHC and flexural stiffnesses of IHAL which are in good agreement with experimental data. The theory developed herein makes it possible to design and optimize structural components from IHAL based on a large class of available constituent fibers.
A Diffusion Tensor Imaging Tractography Algorithm Based on Navier-Stokes Fluid Mechanics
Hageman, Nathan S.; Toga, Arthur W.; Narr, Katherine; Shattuck, David W.
2009-01-01
We introduce a fluid mechanics based tractography method for estimating the most likely connection paths between points in diffusion tensor imaging (DTI) volumes. We customize the Navier-Stokes equations to include information from the diffusion tensor and simulate an artificial fluid flow through the DTI image volume. We then estimate the most likely connection paths between points in the DTI volume using a metric derived from the fluid velocity vector field. We validate our algorithm using digital DTI phantoms based on a helical shape. Our method segmented the structure of the phantom with less distortion than was produced using implementations of heat-based partial differential equation (PDE) and streamline based methods. In addition, our method was able to successfully segment divergent and crossing fiber geometries, closely following the ideal path through a digital helical phantom in the presence of multiple crossing tracts. To assess the performance of our algorithm on anatomical data, we applied our method to DTI volumes from normal human subjects. Our method produced paths that were consistent with both known anatomy and directionally encoded color (DEC) images of the DTI dataset. PMID:19244007
Novel Design Aspects of the Space Technology 5 Mechanical Subsystem
NASA Technical Reports Server (NTRS)
Rossoni, Peter; McGill, William
2003-01-01
This paper describes several novel design elements of the Space Technology 5 (ST5) spacecraft mechanical subsystem. The spacecraft structure itself takes a significant step in integrating electronics into the primary structure. The deployment system restrains the spacecraft during launch and imparts a predetermined spin rate upon release from its secondary payload accommodations. The deployable instrument boom incorporates some traditional as well as new techniques for lightweight and stiffness. Analysis and test techniques used to validate these technologies are described. Numerous design choices were necessitated due to the compact spacecraft size and strict mechanical subsystem requirements.
Optimal Design of Low-Density SNP Arrays for Genomic Prediction: Algorithm and Applications.
Wu, Xiao-Lin; Xu, Jiaqi; Feng, Guofei; Wiggans, George R; Taylor, Jeremy F; He, Jun; Qian, Changsong; Qiu, Jiansheng; Simpson, Barry; Walker, Jeremy; Bauck, Stewart
2016-01-01
Low-density (LD) single nucleotide polymorphism (SNP) arrays provide a cost-effective solution for genomic prediction and selection, but algorithms and computational tools are needed for the optimal design of LD SNP chips. A multiple-objective, local optimization (MOLO) algorithm was developed for design of optimal LD SNP chips that can be imputed accurately to medium-density (MD) or high-density (HD) SNP genotypes for genomic prediction. The objective function facilitates maximization of non-gap map length and system information for the SNP chip, and the latter is computed either as locus-averaged (LASE) or haplotype-averaged Shannon entropy (HASE) and adjusted for uniformity of the SNP distribution. HASE performed better than LASE with ≤1,000 SNPs, but required considerably more computing time. Nevertheless, the differences diminished when >5,000 SNPs were selected. Optimization was accomplished conditionally on the presence of SNPs that were obligated to each chromosome. The frame location of SNPs on a chip can be either uniform (evenly spaced) or non-uniform. For the latter design, a tunable empirical Beta distribution was used to guide location distribution of frame SNPs such that both ends of each chromosome were enriched with SNPs. The SNP distribution on each chromosome was finalized through the objective function that was locally and empirically maximized. This MOLO algorithm was capable of selecting a set of approximately evenly-spaced and highly-informative SNPs, which in turn led to increased imputation accuracy compared with selection solely of evenly-spaced SNPs. Imputation accuracy increased with LD chip size, and imputation error rate was extremely low for chips with ≥3,000 SNPs. Assuming that genotyping or imputation error occurs at random, imputation error rate can be viewed as the upper limit for genomic prediction error. Our results show that about 25% of imputation error rate was propagated to genomic prediction in an Angus population. The
NASA Astrophysics Data System (ADS)
Gowen, A. A.; O'Donnell, C. P.
2009-05-01
White mushrooms were subjected to mechanical injury by controlled shaking in a plastic box at 400 rpm for different times (0, 60, 120, 300 and 600 s). Immediately after shaking, hyperspectral images were obtained using two pushbroom line-scanning hyperspectral imaging instruments, one operating in the wavelength range of 400 - 1000 nm with spectroscopic resolution of 5 nm, the other operating in the wavelength range of 950 - 1700 nm with spectroscopic resolution of 7 nm. Different spectral and spatial pretreatments were investigated to reduce the effect of sample curvature on hyperspectral data. Algorithms based on Chemometric techniques (Principal Component Analysis and Partial Least Squares Discriminant Analysis) and image processing methods (masking, thresholding, morphological operations) were developed for pixel classification in hyperspectral images. In addition, correlation analysis, spectral angle mapping and scaled difference of sample spectra were investigated and compared with the chemometric approaches.
Quantum mechanical NMR simulation algorithm for protein-size spin systems
NASA Astrophysics Data System (ADS)
Edwards, Luke J.; Savostyanov, D. V.; Welderufael, Z. T.; Lee, Donghan; Kuprov, Ilya
2014-06-01
Nuclear magnetic resonance spectroscopy is one of the few remaining areas of physical chemistry for which polynomially scaling quantum mechanical simulation methods have not so far been available. In this communication we adapt the restricted state space approximation to protein NMR spectroscopy and illustrate its performance by simulating common 2D and 3D liquid state NMR experiments (including accurate description of relaxation processes using Bloch-Redfield-Wangsness theory) on isotopically enriched human ubiquitin - a protein containing over a thousand nuclear spins forming an irregular polycyclic three-dimensional coupling lattice. The algorithm uses careful tailoring of the density operator space to only include nuclear spin states that are populated to a significant extent. The reduced state space is generated by analysing spin connectivity and decoherence properties: rapidly relaxing states as well as correlations between topologically remote spins are dropped from the basis set.
NASA Astrophysics Data System (ADS)
Degtyarev, Alexander; Khramushin, Vasily
2016-02-01
The paper deals with the computer implementation of direct computational experiments in fluid mechanics, constructed on the basis of the approach developed by the authors. The proposed approach allows the use of explicit numerical scheme, which is an important condition for increasing the effciency of the algorithms developed by numerical procedures with natural parallelism. The paper examines the main objects and operations that let you manage computational experiments and monitor the status of the computation process. Special attention is given to a) realization of tensor representations of numerical schemes for direct simulation; b) realization of representation of large particles of a continuous medium motion in two coordinate systems (global and mobile); c) computing operations in the projections of coordinate systems, direct and inverse transformation in these systems. Particular attention is paid to the use of hardware and software of modern computer systems.
Duarte, Belmiro P.M.; Wong, Weng Kee; Atkinson, Anthony C.
2016-01-01
T-optimum designs for model discrimination are notoriously difficult to find because of the computational difficulty involved in solving an optimization problem that involves two layers of optimization. Only a handful of analytical T-optimal designs are available for the simplest problems; the rest in the literature are found using specialized numerical procedures for a specific problem. We propose a potentially more systematic and general way for finding T-optimal designs using a Semi-Infinite Programming (SIP) approach. The strategy requires that we first reformulate the original minimax or maximin optimization problem into an equivalent semi-infinite program and solve it using an exchange-based method where lower and upper bounds produced by solving the outer and the inner programs, are iterated to convergence. A global Nonlinear Programming (NLP) solver is used to handle the subproblems, thus finding the optimal design and the least favorable parametric configuration that minimizes the residual sum of squares from the alternative or test models. We also use a nonlinear program to check the global optimality of the SIP-generated design and automate the construction of globally optimal designs. The algorithm is successfully used to produce results that coincide with several T-optimal designs reported in the literature for various types of model discrimination problems with normally distributed errors. However, our method is more general, merely requiring that the parameters of the model be estimated by a numerical optimization. PMID:27330230
Thermo-mechanical design aspects of mercury bombardment ion thrusters.
NASA Technical Reports Server (NTRS)
Schnelker, D. E.; Kami, S.
1972-01-01
The mechanical design criteria are presented as background considerations for solving problems associated with the thermomechanical design of mercury ion bombardment thrusters. Various analytical procedures are used to aid in the development of thruster subassemblies and components in the fields of heat transfer, vibration, and stress analysis. Examples of these techniques which provide computer solutions to predict and control stress levels encountered during launch and operation of thruster systems are discussed. Computer models of specific examples are presented.
NASA Astrophysics Data System (ADS)
Cozzani, A.; Sarti, B.; Casarosa, G.; Ratti, F.; Appolloni, M.
2003-09-01
One of the experiments on board of the Material Exposure and Degradation Experiment on Eutef (MEDET) consists of a Spectrometer. The aim of the experiment is to study the degradation of the properties of optical materials exposed to near earth orbit space environment. The samples of optical materials under investigation are placed on a rotating wheel. A drive mechanism is used to rotate the wheel and position each sample in front of the optical diffuser and the spectrometer sensor. The first step of the design was the choice of the components and the choice of the materials for the mechanical parts. Then, the detailed mechanical design of the assembly has been carried out. The mechanism has been designed in order to be integrated inside MEDET. This has posed constraints in terms of geometry and power budget for the components. A structural analysis of the drive mechanism assembly has been carried out to ensure the integrity of the mechanism during launch. The sample wheel is driven by a stepper motor that has been controlled by a closed-loop algorithm. The choice of the type of control has been driven by in orbit reliability considerations. A breadboard of the mechanism has been assembled in ESTEC laboratory to perform a drive control test. Challenges of the design have been the very limited time available for the overall concept and validation and the limited resources for the project that has been classified as a low cost experiment. The work has been carried out in the ESTEC laboratories with a close collaboration between mechanical and electrical engineers of the testing and material department.
Adaptive filter design based on the LMS algorithm for delay elimination in TCR/FC compensators.
Hooshmand, Rahmat Allah; Torabian Esfahani, Mahdi
2011-04-01
Thyristor controlled reactor with fixed capacitor (TCR/FC) compensators have the capability of compensating reactive power and improving power quality phenomena. Delay in the response of such compensators degrades their performance. In this paper, a new method based on adaptive filters (AF) is proposed in order to eliminate delay and increase the response of the TCR compensator. The algorithm designed for the adaptive filters is performed based on the least mean square (LMS) algorithm. In this design, instead of fixed capacitors, band-pass LC filters are used. To evaluate the filter, a TCR/FC compensator was used for nonlinear and time varying loads of electric arc furnaces (EAFs). These loads caused occurrence of power quality phenomena in the supplying system, such as voltage fluctuation and flicker, odd and even harmonics and unbalancing in voltage and current. The above design was implemented in a realistic system model of a steel complex. The simulation results show that applying the proposed control in the TCR/FC compensator efficiently eliminated delay in the response and improved the performance of the compensator in the power system. PMID:21193194
Simulation of Propellant Loading System Senior Design Implement in Computer Algorithm
NASA Technical Reports Server (NTRS)
Bandyopadhyay, Alak
2010-01-01
Propellant loading from the Storage Tank to the External Tank is one of the very important and time consuming pre-launch ground operations for the launch vehicle. The propellant loading system is a complex integrated system involving many physical components such as the storage tank filled with cryogenic fluid at a very low temperature, the long pipe line connecting the storage tank with the external tank, the external tank along with the flare stack, and vent systems for releasing the excess fuel. Some of the very important parameters useful for design purpose are the prediction of pre-chill time, loading time, amount of fuel lost, the maximum pressure rise etc. The physics involved for mathematical modeling is quite complex due to the fact the process is unsteady, there is phase change as some of the fuel changes from liquid to gas state, then conjugate heat transfer in the pipe walls as well as between solid-to-fluid region. The simulation is very tedious and time consuming too. So overall, this is a complex system and the objective of the work is student's involvement and work in the parametric study and optimization of numerical modeling towards the design of such system. The students have to first become familiar and understand the physical process, the related mathematics and the numerical algorithm. The work involves exploring (i) improved algorithm to make the transient simulation computationally effective (reduced CPU time) and (ii) Parametric study to evaluate design parameters by changing the operational conditions
Elastic mechanism design of a CMM contact probe
NASA Astrophysics Data System (ADS)
Li, Rui-Jun; Fan, Kuang-Chao; Zhou, Hao; Wang, Na; Huang, Qiang-xian
2013-10-01
The measurement of miniature components with a micro- or nano-coordinate measuring machine requires a high precision contact scanning probe. The elastic mechanism of low stiffness is a major component of the contact scanning probe. A new elastic mechanism is analyzed by the theory of elasticity and finite element analysis in this paper. It is to realize the probe's mechanical behavior and stiffness when designing an elastic mechanism for a contact scanning probe. The contact scanning probe is composed of a tungsten stylus with a ruby ball tip, a mechanism of floating plate suspended by four V-shaped leaf springs, and a 3D optical sensor. The leaf spring experiences elastic deformation when a contact force is applied. Uniform stiffness model is analyzed. Simulation and experimental results verify the correctness of the analysis.
NASA Astrophysics Data System (ADS)
Zhao, Sheng; Su, Xiuping; Wu, Ziran; Xu, Chengwen
The paper illustrates the procedure of reliability optimization modeling for contact springs of AC contactors under nonlinear multi-constraint conditions. The adaptive genetic algorithm (AGA) is utilized to perform reliability optimization on the contact spring parameters of a type of AC contactor. A method that changes crossover and mutation rates at different times in the AGA can effectively avoid premature convergence, and experimental tests are performed after optimization. The experimental result shows that the mass of each optimized spring is reduced by 16.2%, while the reliability increases to 99.9% from 94.5%. The experimental result verifies the correctness and feasibility of this reliability optimization designing method.
Binary TLBO algorithm assisted for designing plasmonic nano bi-pyramids-based absorption coefficient
NASA Astrophysics Data System (ADS)
Akhlaghi, Majid; Emami, Farzin; Nozhat, Najmeh
2014-07-01
A new efficient binary optimization method based on Teaching-Learning-Based Optimization (TLBO) algorithm is proposed to design an array of plasmonic nano bi-pyramids in order to achieve maximum absorption coefficient spectrum. In binary TLBO, a group of learners consisting of a matrix with binary entries controls the presence ('1') or the absence ('0') of nanoparticles in the array. Simulation results show that absorption coefficient strongly depends on the localized position of plasmonic nanoparticles. Non-periodic structures have more appropriate response in term of absorption coefficient. This approach is useful in optical applications such as solar cells and plasmonic nano antenna.
Mechanism Design for the Online Allocation of Items without Monetary Payments
NASA Astrophysics Data System (ADS)
Jalilzadeh, Behnam; Planken, Léon; de Weerdt, Mathijs
We consider online mechanism design without money, where agents are allowed to trade items with other agents, in an attempt to improve their own allocation. In an off-line context, this problem is known as the House Allocation Problem (HAP). We extend HAP to an online problem and call it the Online House Allocation Problem (OHAP) . In OHAP, agents can choose when to arrive and depart over time and are allowed to be indifferent between items. Subsequently, we present our Agent Shifting Algorithm (ASA) for OHAP . A mechanism that uses ASA as its allocation rule is shown to be strategy-proof, individually rational and Pareto optimal. Moreover, we argue that any mechanism that obtains an outcome in OHAP that cannot be obtained by using ASA fails to be strategy-proof or is not Pareto optimal.
Designing a mirrored Howland circuit with a particle swarm optimisation algorithm
NASA Astrophysics Data System (ADS)
Bertemes-Filho, Pedro; Negri, Lucas H.; Vincence, Volney C.
2016-06-01
Electrical impedance spectroscopy usually requires a wide bandwidth current source with high output impedance. Non-idealities of the operational amplifier (op-amp) degrade its performance. This work presents a particle swarm algorithm for extracting the main AC characteristics of the op-amp used to design a mirrored modified Howland current source circuit which satisfies both the output current and the impedance spectra required. User specifications were accommodated. Both resistive and biological loads were used in the simulations. The results showed that the algorithm can correctly identify the open-loop gain and the input and output resistance of the op-amp which best fit the performance requirements of the circuit. It was also shown that the higher the open-loop gain corner frequency the higher the output impedance of the circuit. The algorithm could be a powerful tool for developing a desirable current source for different bioimpedance medical and clinical applications, such as cancer tissue characterisation and tissue cell measurements.
Object-Oriented/Data-Oriented Design of a Direct Simulation Monte Carlo Algorithm
NASA Technical Reports Server (NTRS)
Liechty, Derek S.
2014-01-01
Over the past decade, there has been much progress towards improved phenomenological modeling and algorithmic updates for the direct simulation Monte Carlo (DSMC) method, which provides a probabilistic physical simulation of gas Rows. These improvements have largely been based on the work of the originator of the DSMC method, Graeme Bird. Of primary importance are improved chemistry, internal energy, and physics modeling and a reduction in time to solution. These allow for an expanded range of possible solutions In altitude and velocity space. NASA's current production code, the DSMC Analysis Code (DAC), is well-established and based on Bird's 1994 algorithms written in Fortran 77 and has proven difficult to upgrade. A new DSMC code is being developed in the C++ programming language using object-oriented and data-oriented design paradigms to facilitate the inclusion of the recent improvements and future development activities. The development efforts on the new code, the Multiphysics Algorithm with Particles (MAP), are described, and performance comparisons are made with DAC.
Utilizing the Hotelling template as a tool for CT image reconstruction algorithm design
NASA Astrophysics Data System (ADS)
Sanchez, Adrian A.; Sidky, Emil Y.; Pan, Xiaochuan
2012-02-01
Design of image reconstruction algorithms for CT can be significantly aided by useful metrics of image quality. Useful metrics, however, are difficult to develop due to the high-dimensionality of the CT imaging system, lack of spatial invariance in the imaging system, and a high degree of correlation among the image voxels. Although true task-based evaluation on realistic imaging tasks can be time-consuming, and a given task may be insensitive to the image reconstruction algorithm, task-based metrics can still prove useful in many contexts. For example, model observers that mimic performance of the imaging system on specific tasks can provide a low-dimensional measure of image quality while still accounting for many of the salient properties of the system and object being scanned. In this work, ideal observer performance is computed on a single detection task. The modeled signal for detection is taken to be very small - size on the order of a detector bin - and inspection of the accompanying Hotelling template is suggested. We hypothesize that improved detection on small signals may be sensitive to the reconstruction algorithm. Further, we hypothesize that structurally simple Hotelling templates may correlate with high human observer performance.
The Hierarchical Specification and Mechanical Verification of the SIFT Design
NASA Technical Reports Server (NTRS)
1983-01-01
The formal specification and proof methodology employed to demonstrate that the SIFT computer system meets its requirements are described. The hierarchy of design specifications is shown, from very abstract descriptions of system function down to the implementation. The most abstract design specifications are simple and easy to understand, almost all details of the realization were abstracted out, and are used to ensure that the system functions reliably and as intended. A succession of lower level specifications refines these specifications into more detailed, and more complex, views of the system design, culminating in the Pascal implementation. The section describes the rigorous mechanical proof that the abstract specifications are satisfied by the actual implementation.
Metamorphic manipulating mechanism design for MCCB using index reduced iteration
NASA Astrophysics Data System (ADS)
Xu, Jinghua; Zhang, Shuyou; Zhao, Zhen; Lin, Xiaoxia
2013-03-01
The present research on moulded case circuit breaker(MCCB) focuses on the enhancement of current-limiting interrupting performance during short circuit, overload, under voltage and phase failure, involving electrics, magnetic, mechanics, thermal, material, friction, arc extinguishing, impact vibration, skin effect, etc. The rigid-flexible coupling of the parts and components of the metamorphic manipulating mechanism in multi-fields leads to the non-rigid, high frequency, high damping, singularity of the Euler-Lagrange equations which represents the multi-body dynamics. The small step iteration which is used for obtaining the instantaneous and short time critical interrupting performance of metamorphic mechanism appears inaccuracy. It is difficult to realize top-down design by existing CAD systems. Therefore, a metamorphic manipulating mechanism design method for MCCB using index reduced iteration(IRI) is put forward. The metamorphic manipulating mechanism of MCCB is decomposed into three mechanisms: main switch connector mechanism, electromagnet-drawbar-jump buckle mechanism, and bimetallic strip-drawbar mechanism, which is respectively described by electro-dynamic force, electromagnet force, and bimetallic strip force. The dummy part(virtual rigid) without moment of inertia and mass is employed as intermediate to join the flexible body and rigid body. The model of rigid-flexible coupling metamorphic mechanism multi-body dynamics is built. The differential algebraic equations(DAEs) of the multibody dynamics model are converted to pure ordinary differential equations(ODEs) by coordinate partition. Order reduced integration with multi-step and variable step-size is preceded based on IRI. The non-linear algebraic equations are solved in each integration step by Newton-Rapson iteration. There is no ill-condition and singularity of Jacobian matrix when step size reduces to zero. The independent prototype design system using ACIS R13, HOOPS V11.0 and Visual C++.NET 2003
Multi-Stage Hybrid Rocket Conceptual Design for Micro-Satellites Launch using Genetic Algorithm
NASA Astrophysics Data System (ADS)
Kitagawa, Yosuke; Kitagawa, Koki; Nakamiya, Masaki; Kanazaki, Masahiro; Shimada, Toru
The multi-objective genetic algorithm (MOGA) is applied to the multi-disciplinary conceptual design problem for a three-stage launch vehicle (LV) with a hybrid rocket engine (HRE). MOGA is an optimization tool used for multi-objective problems. The parallel coordinate plot (PCP), which is a data mining method, is employed in the post-process in MOGA for design knowledge discovery. A rocket that can deliver observing micro-satellites to the sun-synchronous orbit (SSO) is designed. It consists of an oxidizer tank containing liquid oxidizer, a combustion chamber containing solid fuel, a pressurizing tank and a nozzle. The objective functions considered in this study are to minimize the total mass of the rocket and to maximize the ratio of the payload mass to the total mass. To calculate the thrust and the engine size, the regression rate is estimated based on an empirical model for a paraffin (FT-0070) propellant. Several non-dominated solutions are obtained using MOGA, and design knowledge is discovered for the present hybrid rocket design problem using a PCP analysis. As a result, substantial knowledge on the design of an LV with an HRE is obtained for use in space transportation.
Making software get along: integrating optical and mechanical design programs
NASA Astrophysics Data System (ADS)
Shackelford, Christie J.; Chinnock, Randal B.
2001-03-01
As modern optomechanical engineers, we have the good fortune of having very sophisticated software programs available to us. The current optical design, mechanical design, industrial design, and CAM programs are very powerful tools with some very desirable features. However, no one program can do everything necessary to complete an entire optomechanical system design. Each program has a unique set of features and benefits, and typically two or mo re will be used during the product development process. At a minimum, an optical design program and a mechanical CAD package will be employed. As we strive for efficient, cost-effective, and rapid progress in our development projects, we must use these programs to their full advantage, while keeping redundant tasks to a minimum. Together, these programs offer the promise of a `seamless' flow of data from concept all the way to the download of part designs directly to the machine shop for fabrication. In reality, transferring data from one software package to the next is often frustrating. Overcoming these problems takes some know-how, a bit of creativity, and a lot of persistence. This paper describes a complex optomechanical development effort in which a variety of software tools were used from the concept stage to prototyping. It will describe what software was used for each major design task, how we learned to use them together to best advantage, and how we overcame the frustrations of software that didn't get along.
An efficient algorithm for systematic analysis of nucleotide strings suitable for siRNA design
2011-01-01
Background The "off-target" silencing effect hinders the development of siRNA-based therapeutic and research applications. Existing solutions for finding possible locations of siRNA seats within a large database of genes are either too slow, miss a portion of the targets, or are simply not designed to handle a very large number of queries. We propose a new approach that reduces the computational time as compared to existing techniques. Findings The proposed method employs tree-based storage in a form of a modified truncated suffix tree to sort all possible short string substrings within given set of strings (i.e. transcriptome). Using the new algorithm, we pre-computed a list of the best siRNA locations within each human gene ("siRNA seats"). siRNAs designed to reside within siRNA seats are less likely to hybridize off-target. These siRNA seats could be used as an input for the traditional "set-of-rules" type of siRNA designing software. The list of siRNA seats is available through a publicly available database located at http://web.cos.gmu.edu/~gmanyam/siRNA_db/search.php Conclusions In attempt to perform top-down prediction of the human siRNA with minimized off-target hybridization, we developed an efficient algorithm that employs suffix tree based storage of the substrings. Applications of this approach are not limited to optimal siRNA design, but can also be useful for other tasks involving selection of the characteristic strings specific to individual genes. These strings could then be used as siRNA seats, as specific probes for gene expression studies by oligonucleotide-based microarrays, for the design of molecular beacon probes for Real-Time PCR and, generally, any type of PCR primers. PMID:21619643
Multispectral linear array (MLA) focal plane mechanical and thermal design
NASA Technical Reports Server (NTRS)
Mitchell, A. S.; Kaminski, E. F.
1982-01-01
The mechanical and thermal design of an integrated focal plane subsystem of a Multispectral Linear Array (MLA) instrument is discussed in terms of focal-plane alignment, thermoelastic performance, and thermal requirements. The modular construction and thermal control of the focal plane array are discussed.
Computer-based mechanical design of overhead lines
NASA Astrophysics Data System (ADS)
Rusinaru, D.; Bratu, C.; Dinu, R. C.; Manescu, L. G.
2016-02-01
Beside the performance, the safety level according to the actual standards is a compulsory condition for distribution grids’ operation. Some of the measures leading to improvement of the overhead lines reliability ask for installations’ modernization. The constraints imposed to the new lines components refer to the technical aspects as thermal stress or voltage drop, and look for economic efficiency, too. The mechanical sizing of the overhead lines is after all an optimization problem. More precisely, the task in designing of the overhead line profile is to size poles, cross-arms and stays and locate poles along a line route so that the total costs of the line's structure to be minimized and the technical and safety constraints to be fulfilled.The authors present in this paper an application for the Computer-Based Mechanical Design of the Overhead Lines and the features of the corresponding Visual Basic program, adjusted to the distribution lines. The constraints of the optimization problem are adjusted to the existing weather and loading conditions of Romania. The outputs of the software application for mechanical design of overhead lines are: the list of components chosen for the line: poles, cross-arms, stays; the list of conductor tension and forces for each pole, cross-arm and stay for different weather conditions; the line profile drawings.The main features of the mechanical overhead lines design software are interactivity, local optimization function and high-level user-interface
Design and testing of the LITE Variable Field Stop mechanism
NASA Technical Reports Server (NTRS)
Dillman, Robert A.
1993-01-01
The Variable Field Stop (VFS) is a rotary mechanism that reliably positions any of four aperture plates in the optical path of a spaceflight experiment, limiting the amount of light reaching the detectors. This paper discusses the design, operation, and testing of the VFS.
Using a Simple Contest to Illustrate Mechanism Design
ERIC Educational Resources Information Center
Blackwell, Calvin
2011-01-01
This article describes a simple classroom activity that illustrates how economic theory can be used for mechanism design. The rules for a set of contests are presented; the results typically obtained from these contests illustrate how the prize structure can be manipulated in order to produce a particular outcome. Specifically, this activity is…
Computer-aided design and analysis of mechanisms
NASA Technical Reports Server (NTRS)
Knight, F. L.
1982-01-01
An introduction to the computer programs developed to assist in the design and analysis of mechanisms is presented. A survey of the various types of programs which are available is given, and the most widely used programs are compared. The way in which the programs are used is discussed, and demonstrated with an example.
Algorithmic considerations of integrated design for CSI on a hypercube architecture
NASA Technical Reports Server (NTRS)
Oezguener, UE.; Oezguener, F.
1989-01-01
An approach is presented to the integrated design problem for actively controlled large, flexible mechanical systems for which Control Structure Interaction (CSI) problems are of concern. The two coupled design problems were identified as the optimal Structural Design problem the optimal Controller Design problem. These two problems can be addressed within a decision making loop that would consider each separately, and then sequentially analyze the effects of one on the other. Embedded in such a loop would be the simulation and coordination tasks as part of the decision tools required in a total (software) package. All of the above are compute-intensive tasks. In any such task, possible decompositions and gains due to the inherent parallelism have to be exploited. The problems under consideration, as applied to large flexible mechanical structures, are particularly suited to be mapped onto multicomputer systems in a hypercube topology.
NASA Astrophysics Data System (ADS)
Alpman, Emre
2014-06-01
The effect of selecting the twist angle and chord length distributions on the wind turbine blade design was investigated by performing aerodynamic optimization of a two-bladed stall regulated horizontal axis wind turbine. Twist angle and chord length distributions were defined using Bezier curve using 3, 5, 7 and 9 control points uniformly distributed along the span. Optimizations performed using a micro-genetic algorithm with populations composed of 5, 10, 15, 20 individuals showed that, the number of control points clearly affected the outcome of the process; however the effects were different for different population sizes. The results also showed the superiority of micro-genetic algorithm over a standard genetic algorithm, for the selected population sizes. Optimizations were also performed using a macroevolutionary algorithm and the resulting best blade design was compared with that yielded by micro-genetic algorithm.
Mechanics of swimming of multi-body bacterial swarmers using non-labeled cell tracking algorithm
NASA Astrophysics Data System (ADS)
Phuyal, Kiran; Kim, Min Jun
2013-01-01
To better understand the survival strategy of bacterial swarmers and the mechanical advantages offered by the linear chain (head-tail) attachment of the multiple bacterial bodies in an individual swarmer cell at low Reynolds number, a non-labeled cell tracking algorithm was used to quantify the mechanics of multi-body flagellated bacteria, Serratia marcescens, swimming in a motility buffer that originally exhibited the swarming motility. Swarming is a type of bacterial motility that is characterized by the collective coordinated motion of differentiated swarmer cells on a two-dimensional surface such as agar. In this study, the bacterial swarmers with multiple cell bodies (2, 3, and 4) were extracted from the swarm plate, and then tracked individually after resuspending in the motility medium. Their motion was investigated and compared with individual undifferentiated swimming bacterial cells. The swarmers when released into the motility buffer swam actively without tumbles. Their speeds, orientations, and the diffusive properties were studied by tracking the individual cell trajectories over a short distance in two-dimensional field when the cells are swimming at a constant depth in a bulk aqueous environment. At short time scales, the ballistic trajectory was dominant for both multi-body swarmers and undifferentiated cells.
Hebert, T.J. |; Moore, W.H.; Dhekne, R.D.; Ford, P.V.; Wendt, J.A.; Murphy, P.H.; Ting, Y.
1996-08-01
The design of an automated computer algorithm for labeling the cardiac blood pool within gated 3-D reconstructions of the radiolabeled red blood cells is investigated. Due to patient functional abnormalities, limited resolution, and noise, certain spatial and temporal features of the cardiac blood pool that one would anticipate finding in every study are not present in certain frames or with certain patients. The labeling of the cardiac blood pool requires an algorithm that only relies upon features present in all patients. The authors investigate the design of a fully-automated region growing algorithm for this purpose.
Fuzzy rule base design using tabu search algorithm for nonlinear system modeling.
Bagis, Aytekin
2008-01-01
This paper presents an approach to fuzzy rule base design using tabu search algorithm (TSA) for nonlinear system modeling. TSA is used to evolve the structure and the parameter of fuzzy rule base. The use of the TSA, in conjunction with a systematic neighbourhood structure for the determination of fuzzy rule base parameters, leads to a significant improvement in the performance of the model. To demonstrate the effectiveness of the presented method, several numerical examples given in the literature are examined. The results obtained by means of the identified fuzzy rule bases are compared with those belonging to other modeling approaches in the literature. The simulation results indicate that the method based on the use of a TSA performs an important and very effective modeling procedure in fuzzy rule base design in the modeling of the nonlinear or complex systems. PMID:17945233
NASA Astrophysics Data System (ADS)
Wahyudi, Eko Januari
2013-09-01
As advancing application of soft computation technique in oil and gas industry, Genetic Algorithm (GA) also shows contribution in geophysical inverse problems in order to achieve better results and efficiency in computational process. In this paper, I would like to show the progress of my work in inverse modeling of time-lapse gravity data uses value encoding with alphabet formulation. The alphabet formulation designed to provide solution of characterization positive density change (+Δρ) and negative density change (-Δρ) respect to reference value (0 gr/cc). The inversion that utilize discrete model parameter, computed with GA as optimization algorithm. The challenge working with GA is take long time computational process, so the step in designing GA in this paper described through evaluation on GA operators performance test. The performances of several combinations of GA operators (selection, crossover, mutation, and replacement) tested with synthetic model in single-layer reservoir. Analysis on sufficient number of samples shows combination of SUS-MPCO-QSA/G-ND as the most promising results. Quantitative solution with more confidence level to characterize sharp boundary of density change zones was conducted with average calculation of sufficient model samples.
ERIC Educational Resources Information Center
Schoolcraft Coll., Livonia, MI.
This document is a curriculum guide for a program in mechanical design technology (computer-assisted drafting and design developed at Schoolcraft College, Livonia, Michigan). The program helps students to acquire the skills of drafters and to interact with electronic equipment, with the option of becoming efficient in the computer-aided…
NASA Astrophysics Data System (ADS)
Sarjaš, Andrej; Chowdhury, Amor; Svečko, Rajko
2016-09-01
This paper presents the synthesis of an optimal robust controller design using the polynomial pole placement technique and multi-criteria optimisation procedure via an evolutionary computation algorithm - differential evolution. The main idea of the design is to provide a reliable fixed-order robust controller structure and an efficient closed-loop performance with a preselected nominally characteristic polynomial. The multi-criteria objective functions have quasi-convex properties that significantly improve convergence and the regularity of the optimal/sub-optimal solution. The fundamental aim of the proposed design is to optimise those quasi-convex functions with fixed closed-loop characteristic polynomials, the properties of which are unrelated and hard to present within formal algebraic frameworks. The objective functions are derived from different closed-loop criteria, such as robustness with metric ?∞, time performance indexes, controller structures, stability properties, etc. Finally, the design results from the example verify the efficiency of the controller design and also indicate broader possibilities for different optimisation criteria and control structures.
NASA Technical Reports Server (NTRS)
Spinhirne, James D.; Palm, Stephen P.; Hlavka, Dennis L.; Hart, William D.
2007-01-01
The Geoscience Laser Altimeter System (GLAS) launched in early 2003 is the first polar orbiting satellite lidar. The instrument design includes high performance observations of the distribution and optical scattering cross sections of atmospheric clouds and aerosol. The backscatter lidar operates at two wavelengths, 532 and 1064 nm. For the atmospheric cloud and aerosol measurements, the 532 nm channel was designed for ultra high efficiency with solid state photon counting detectors and etalon filtering. Data processing algorithms were developed to calibrate and normalize the signals and produce global scale data products of the height distribution of cloud and aerosol layers and their optical depths and particulate scattering cross sections up to the limit of optical attenuation. The paper will concentrate on the effectiveness and limitations of the lidar channel design and data product algorithms. Both atmospheric receiver channels meet and exceed their design goals. Geiger Mode Avalanche Photodiode modules are used for the 532 nm signal. The operational experience is that some signal artifacts and non-linearity require correction in data processing. As with all photon counting detectors, a pulse-pile-up calibration is an important aspect of the measurement. Additional signal corrections were found to be necessary relating to correction of a saturation signal-run-on effect and also for daytime data, a small range dependent variation in the responsivity. It was possible to correct for these signal errors in data processing and achieve the requirement to accurately profile aerosol and cloud cross section down to 10-7 llm-sr. The analysis procedure employs a precise calibration against molecular scattering in the mid-stratosphere. The 1064 nm channel detection employs a high-speed analog APD for surface and atmospheric measurements where the detection sensitivity is limited by detector noise and is over an order of magnitude less than at 532 nm. A unique feature of
GMI Spin Mechanism Assembly Design, Development, and Test Results
NASA Technical Reports Server (NTRS)
Woolaway, Scott; Kubitschek, Michael; Berdanier, Barry; Newell, David; Dayton, Chris; Pellicciotti, Joseph W.
2012-01-01
The GMI Spin Mechanism Assembly (SMA) is a precision bearing and power transfer drive assembly mechanism that supports and spins the Global Microwave Imager (GMI) instrument at a constant rate of 32 rpm continuously for the 3 year plus mission life. The GMI instrument will fly on the core Global Precipitation Measurement (GPM) spacecraft and will be used to make calibrated radiometric measurements at multiple microwave frequencies and polarizations. The GPM mission is an international effort managed by the National Aeronautics and Space Administration (NASA) to improve climate, weather, and hydro-meteorological predictions through more accurate and frequent precipitation measurements [1]. Ball Aerospace and Technologies Corporation (BATC) was selected by NASA Goddard Space Flight Center (GSFC) to design, build, and test the GMI instrument. The SMA design has to meet a challenging set of requirements and is based on BATC space mechanisms heritage and lessons learned design changes made to the WindSat BAPTA mechanism that is currently operating on orbit and has recently surpassed 8 years of Flight operation.
A possibilistic approach to rotorcraft design through a multi-objective evolutionary algorithm
NASA Astrophysics Data System (ADS)
Chae, Han Gil
Most of the engineering design processes in use today in the field may be considered as a series of successive decision making steps. The decision maker uses information at hand, determines the direction of the procedure, and generates information for the next step and/or other decision makers. However, the information is often incomplete, especially in the early stages of the design process of a complex system. As the complexity of the system increases, uncertainties eventually become unmanageable using traditional tools. In such a case, the tools and analysis values need to be "softened" to account for the designer's intuition. One of the methods that deals with issues of intuition and incompleteness is possibility theory. Through the use of possibility theory coupled with fuzzy inference, the uncertainties estimated by the intuition of the designer are quantified for design problems. By involving quantified uncertainties in the tools, the solutions can represent a possible set, instead of a crisp spot, for predefined levels of certainty. From a different point of view, it is a well known fact that engineering design is a multi-objective problem or a set of such problems. The decision maker aims to find satisfactory solutions, sometimes compromising the objectives that conflict with each other. Once the candidates of possible solutions are generated, a satisfactory solution can be found by various decision-making techniques. A number of multi-objective evolutionary algorithms (MOEAs) have been developed, and can be found in the literature, which are capable of generating alternative solutions and evaluating multiple sets of solutions in one single execution of an algorithm. One of the MOEA techniques that has been proven to be very successful for this class of problems is the strength Pareto evolutionary algorithm (SPEA) which falls under the dominance-based category of methods. The Pareto dominance that is used in SPEA, however, is not enough to account for the
Optimization design of wind turbine drive train based on Matlab genetic algorithm toolbox
NASA Astrophysics Data System (ADS)
Li, R. N.; Liu, X.; Liu, S. J.
2013-12-01
In order to ensure the high efficiency of the whole flexible drive train of the front-end speed adjusting wind turbine, the working principle of the main part of the drive train is analyzed. As critical parameters, rotating speed ratios of three planetary gear trains are selected as the research subject. The mathematical model of the torque converter speed ratio is established based on these three critical variable quantity, and the effect of key parameters on the efficiency of hydraulic mechanical transmission is analyzed. Based on the torque balance and the energy balance, refer to hydraulic mechanical transmission characteristics, the transmission efficiency expression of the whole drive train is established. The fitness function and constraint functions are established respectively based on the drive train transmission efficiency and the torque converter rotating speed ratio range. And the optimization calculation is carried out by using MATLAB genetic algorithm toolbox. The optimization method and results provide an optimization program for exact match of wind turbine rotor, gearbox, hydraulic mechanical transmission, hydraulic torque converter and synchronous generator, ensure that the drive train work with a high efficiency, and give a reference for the selection of the torque converter and hydraulic mechanical transmission.
Some mechanical design aspects of the European Robotic Arm
NASA Technical Reports Server (NTRS)
Lambooy, Peter J.; Mandersloot, Wart M.; Bentall, Richard H.
1995-01-01
The European Robotic Arm (ERA) is a contribution to the Russian Segment of the International Space Station Alpha. It will start operating on the Russian Segment during the assembly phase. ERA is designed and produced by a large industrial consortium spread over Europe with Fokker Space & Systems as prime contractor. In this paper, we will describe some of the overall design aspects and focus on the development of several mechanisms within ERA. The operation of ERA during the approach of its end effector towards the grapple interface and the grapple operation is discussed, with a focus on mechanisms. This includes the geometry of the end effector leading edge, which is carefully designed to provide the correct and complete tactile information to a torque-force sensor (TFS). The data from this TFS are used to steer the arm such that forces and moments are kept below 20 N and 20 N.m respectively during the grappling operation. Two hardware models of the end effector are built. The problems encountered are described as well as their solutions. The joints in the wrists and the elbow initially used a harmonic drive lubricated by MoS2. During development testing, this combination showed an insufficient lifetime in air to survive the acceptance test program. The switch-over to a system comprising planetary gearboxes with grease lubrication is described. From these development efforts, conclusions are drawn and recommendations are given for the design of complex space mechanisms.
Some mechanical design aspects of the European Robotic Arm
NASA Astrophysics Data System (ADS)
Lambooy, Peter J.; Mandersloot, Wart M.; Bentall, Richard H.
1995-05-01
The European Robotic Arm (ERA) is a contribution to the Russian Segment of the International Space Station Alpha. It will start operating on the Russian Segment during the assembly phase. ERA is designed and produced by a large industrial consortium spread over Europe with Fokker Space & Systems as prime contractor. In this paper, we will describe some of the overall design aspects and focus on the development of several mechanisms within ERA. The operation of ERA during the approach of its end effector towards the grapple interface and the grapple operation is discussed, with a focus on mechanisms. This includes the geometry of the end effector leading edge, which is carefully designed to provide the correct and complete tactile information to a torque-force sensor (TFS). The data from this TFS are used to steer the arm such that forces and moments are kept below 20 N and 20 N.m respectively during the grappling operation. Two hardware models of the end effector are built. The problems encountered are described as well as their solutions. The joints in the wrists and the elbow initially used a harmonic drive lubricated by MoS2. During development testing, this combination showed an insufficient lifetime in air to survive the acceptance test program. The switch-over to a system comprising planetary gearboxes with grease lubrication is described. From these development efforts, conclusions are drawn and recommendations are given for the design of complex space mechanisms.
NASA Astrophysics Data System (ADS)
Lin, Yong; Hu, Jiasheng; Wu, Kenan
2009-08-01
The vector fuzzy control iterative algorithm (VFCIA) is proposed for the design of phase-only sub-wavelength diffractive optical elements (SWDOEs) for beam shaping. The vector diffraction model put forward by Mansuripur is applied to relate the field distributions between the SWDOE plane and the output plane. Fuzzy control theory is used to decide the constraint method for each iterative process of the algorithm. We have designed a SWDOE that transforms a circular flat-top beam to a square irradiance pattern. Computer design results show that the SWDOE designed by the VFCIA can produce better results than the vector iterative algorithm (VIA). And the finite difference time-domain method (FDTD), a rigorous electromagnetic analysis technique, is used to analyze the designed SWDOE for further confirming the validity of the proposed method.
Mechanical design and evaluation of a slotted CFRP waveguide antenna
NASA Astrophysics Data System (ADS)
Knutsson, L.; Brunzell, S.; Magnusson, H.
A development program for a slotted waveguide array antenna made of metallized CFRP was carried out. The main objective was to minimize the weight of the structure without degrading the electrical and mechanical performance. This paper focuses on mechanical design aspects and manufacturing methods of metallized CFRP waveguides and assembly of an antenna array. A weight saving of approximately 40 percent was accomplished by the CFRP structure compared to a corresponding aluminum structure. Electrical properties and cost were essentially equal for the two concepts.
NASA Astrophysics Data System (ADS)
Tiwari, Rajiv; Waghole, Vikas
2015-07-01
Bearing standards impose restrictions on the internal geometry of spherical roller bearings. Geometrical and strength constraints conditions have been formulated for the optimization of bearing design. The long fatigue life is one of the most important criteria in the optimum design of bearing. The life is directly proportional to the dynamic capacity; hence, the objective function has been chosen as the maximization of dynamic capacity. The effect of speed and static loads acting on the bearing are also taken into account. Design variables for the bearing include five geometrical parameters: the roller diameter, the roller length, the bearing pitch diameter, the number of rollers, and the contact angle. There are a few design constraint parameters which are also included in the optimization, the bounds of which are obtained by initial runs of the optimization. The optimization program is made to run for different values of these design constraint parameters and a range of the parameters is obtained for which the objective function has a higher value. The artificial bee colony algorithm (ABCA) has been used to solve the constrained optimized problem and the optimum design is compared with the one obtained from the grid search method (GSM), both operating independently. Both the ABCA and the GSM have been finally combined together to reach the global optimum point. A constraint violation study has also been carried out to give priority to the constraint having greater possibility of violations. Optimized bearing designs show a better performance parameter with those specified in bearing catalogs. The sensitivity analysis of bearing parameters has also been carried out to see the effect of manufacturing tolerance on the objective function.
NASA Astrophysics Data System (ADS)
Haffner, D. P.; McPeters, R. D.; Bhartia, P. K.; Labow, G. J.
2015-12-01
The TOMS V9 total ozone algorithm will be applied to the OMPS Nadir Mapper instrument to supersede the exisiting V8.6 data product in operational processing and re-processing for public release. Becuase the quality of the V8.6 data is already quite high, enchancements in V9 are mainly with information provided by the retrieval and simplifcations to the algorithm. The design of the V9 algorithm has been influenced by improvements both in our knowledge of atmospheric effects, such as those of clouds made possible by studies with OMI, and also limitations in the V8 algorithms applied to both OMI and OMPS. But the namesake instruments of the TOMS algorithm are substantially more limited in their spectral and noise characterisitics, and a requirement of our algorithm is to also apply the algorithm to these discrete band spectrometers which date back to 1978. To achieve continuity for all these instruments, the TOMS V9 algorithm continues to use radiances in discrete bands, but now uses Rodgers optimal estimation to retrieve a coarse profile and provide uncertainties for each retrieval. The algorithm remains capable of achieving high accuracy results with a small number of discrete wavelengths, and in extreme cases, such as unusual profile shapes and high solar zenith angles, the quality of the retrievals is improved. Despite the intended design to use limited wavlenegths, the algorithm can also utilitze additional wavelengths from hyperspectral sensors like OMPS to augment the retreival's error detection and information content; for example SO2 detection and correction of Ring effect on atmospheric radiances. We discuss these and other aspects of the V9 algorithm as it will be applied to OMPS, and will mention potential improvements which aim to take advantage of a synergy with OMPS Limb Profiler and Nadir Mapper to further improve the quality of total ozone from the OMPS instrument.
Internal Control Rod Drive Mechanisms, Design Options for IRIS
Conway, Lawrence E.; Petrovic, Bojan
2004-07-01
IRIS (International Reactor Innovative and Secure) is a medium-power (335 MWe) PWR with an integral, primary circuit configuration, where all the reactor coolant system components are contained within the reactor vessel. This integral configuration is a key reason for the success of IRIS' 'safety-by-design' approach, whereby accident initiators are eliminated or the accident consequences and/or frequency are reduced. The most obvious example of the IRIS safety by design approach is the elimination of large LOCA's, since the integral reactor coolant system has no large loop piping. Another serious accident scenario that is being addressed in IRIS is the postulated ejection of a reactor control cluster assembly (RCCA). This accident initiator can be eliminated by locating the RCCA drive mechanisms (CRDMs) inside the reactor vessel. This eliminates the mechanical drive rod penetration between the RCCA and the external CRDM, eliminating the potential for differential pressure across the pressure boundary, and thus eliminating 'by design' the possibility for rod ejection accident. Moreover, the elimination of the 'large' drive-rod penetrations and the external CRDM pressure housings decreases the likelihood of boric acid leakage and subsequent corrosion of the reactor pressure boundary (like the Davis-Besse incident). This paper will discuss the IRIS top level design requirements and objectives for internal CRDMs, and provide examples candidate designs and their specific performance characteristics. (authors)
The optical-mechanical design of DMD modulation imaging device
NASA Astrophysics Data System (ADS)
Li, Tianting; Xu, Xiping; Qiao, Yang; Li, Lei; Pan, Yue
2014-09-01
In order to avoid the phenomenon of some image information were lost, which is due to the jamming signals, such as incident laser, make the pixels dot on CCD saturated. In this article a device of optical-mechanical structure was designed, which utilized the DMD (Digital Micro mirror Device) to modulate the image. The DMD reflection imaging optical system adopts the telecentric light path. However, because the design is not only required to guarantee a 66° angle between the optical axis of the relay optics and the DMD, but also to ensure that the optical axis of the projection system keeps parallel with the perpendicular bisector of the micro-mirror which is in the "flat" state, so the TIR prism is introduced，and making the relay optics and the DMD satisfy the optical institution's requirements. In this paper, a mechanical structure of the imaging optical system was designed and at the meanwhile the lens assembly has been well connected and fixed and fine-tuned by detailed structural design, which included the tilt decentered lens, wedge flanges, prisms. By optimizing the design, the issues of mutual restraint between the inverting optical system and the projecting system were well resolved, and prevented the blocking of the two systems. In addition, the structure size of the whole DMD reflection imaging optical system was minimized; it reduced the energy loss and ensured the image quality.
The Mechanical Design Optimization of a High Field HTS Solenoid
Lalitha, SL; Gupta, RC
2015-06-01
This paper describes the conceptual design optimization of a large aperture, high field (24 T at 4 K) solenoid for a 1.7 MJ superconducting magnetic energy storage device. The magnet is designed to be built entirely of second generation (2G) high temperature superconductor tape with excellent electrical and mechanical properties at the cryogenic temperatures. The critical parameters that govern the magnet performance are examined in detail through a multiphysics approach using ANSYS software. The analysis results formed the basis for the performance specification as well as the construction of the magnet.
Harmon, Tyler S; Crabtree, Michael D; Shammas, Sarah L; Posey, Ammon E; Clarke, Jane; Pappu, Rohit V
2016-09-01
Many intrinsically disordered proteins (IDPs) participate in coupled folding and binding reactions and form alpha helical structures in their bound complexes. Alanine, glycine, or proline scanning mutagenesis approaches are often used to dissect the contributions of intrinsic helicities to coupled folding and binding. These experiments can yield confounding results because the mutagenesis strategy changes the amino acid compositions of IDPs. Therefore, an important next step in mutagenesis-based approaches to mechanistic studies of coupled folding and binding is the design of sequences that satisfy three major constraints. These are (i) achieving a target intrinsic alpha helicity profile; (ii) fixing the positions of residues corresponding to the binding interface; and (iii) maintaining the native amino acid composition. Here, we report the development of a G: enetic A: lgorithm for D: esign of I: ntrinsic secondary S: tructure (GADIS) for designing sequences that satisfy the specified constraints. We describe the algorithm and present results to demonstrate the applicability of GADIS by designing sequence variants of the intrinsically disordered PUMA system that undergoes coupled folding and binding to Mcl-1. Our sequence designs span a range of intrinsic helicity profiles. The predicted variations in sequence-encoded mean helicities are tested against experimental measurements. PMID:27503953
NASA Astrophysics Data System (ADS)
Chen, Jing; Liu, Tundong; Jiang, Hao
2016-01-01
A Pareto-based multi-objective optimization approach is proposed to design multichannel FBG filters. Instead of defining a single optimal objective, the proposed method establishes the multi-objective model by taking two design objectives into account, which are minimizing the maximum index modulation and minimizing the mean dispersion error. To address this optimization problem, we develop a two-stage evolutionary computation approach integrating an elitist non-dominated sorting genetic algorithm (NSGA-II) and technique for order preference by similarity to ideal solution (TOPSIS). NSGA-II is utilized to search for the candidate solutions in terms of both objectives. The obtained results are provided as Pareto front. Subsequently, the best compromise solution is determined by the TOPSIS method from the Pareto front according to the decision maker's preference. The design results show that the proposed approach yields a remarkable reduction of the maximum index modulation and the performance of dispersion spectra of the designed filter can be optimized simultaneously.
NASA Astrophysics Data System (ADS)
Wang, Ping; Wu, Guangqiang
2013-03-01
Typical multidisciplinary design optimization(MDO) has gradually been proposed to balance performances of lightweight, noise, vibration and harshness(NVH) and safety for instrument panel(IP) structure in the automotive development. Nevertheless, plastic constitutive relation of Polypropylene(PP) under different strain rates, has not been taken into consideration in current reliability-based and collaborative IP MDO design. In this paper, based on tensile test under different strain rates, the constitutive relation of Polypropylene material is studied. Impact simulation tests for head and knee bolster are carried out to meet the regulation of FMVSS 201 and FMVSS 208, respectively. NVH analysis is performed to obtain mainly the natural frequencies and corresponding mode shapes, while the crashworthiness analysis is employed to examine the crash behavior of IP structure. With the consideration of lightweight, NVH, head and knee bolster impact performance, design of experiment(DOE), response surface model(RSM), and collaborative optimization(CO) are applied to realize the determined and reliability-based optimizations, respectively. Furthermore, based on multi-objective genetic algorithm(MOGA), the optimal Pareto sets are completed to solve the multi-objective optimization(MOO) problem. The proposed research ensures the smoothness of Pareto set, enhances the ability of engineers to make a comprehensive decision about multi-objectives and choose the optimal design, and improves the quality and efficiency of MDO.
Theory and algorithms for a quasi-optical launcher design method for high-frequency gyrotrons
NASA Astrophysics Data System (ADS)
Ungku Farid, Ungku Fazri
Gyrotrons are vacuum tubes that can generate high amounts of coherent high-frequency microwave radiation used for plasma heating, breakdown and current drive, and other applications. The gyrotron output power is not directly usable, and must be converted to either a free-space circular TEM00 Gaussian beam or a HE11 corrugated waveguide mode by employing mode converters. Quasi-optical mode converters (QOMC) achieve this by utilizing a launcher (a type of waveguide antenna) and a mirror system. Adding perturbations to smooth-wall launchers can produce a better Gaussian shaped radiation pattern with smaller side lobes and less diffraction, and this improvement leads to higher power efficiency in the QOMC. The oversize factor (OF) is defined as the ratio of the operating to cutoff frequency of the launcher, and the higher this value is, the more difficult it is to obtain good launcher designs. This thesis presents a new method for the design of any perturbed-wall TE 0n launcher that is not too highly oversized, and it is an improvement over previous launcher design methods that do not work well for highly oversized launchers. This new launcher design method is a fusion of three different methods, which are the Iterative Stratton-Chu algorithm (used for fast and accurate waveguide field propagations), the Katsenelenbaum-Semenov phase-correcting optimization algorithm, and Geometrical Optics. Three different TE02 launchers were designed using this new method, 1) a highly oversized (2.49 OF) 60 GHz launcher as proof-of-method, 2) a highly oversized (2.66 OF) 28 GHz launcher for possible use in the quasihelically symmetric stellarator (HSX) transmission line at the University of Wisconsin -- Madison, and 3) a compact internal 94 GHz 1.54 OF launcher for use in a compact gyrotron. Good to excellent results were achieved, and all launcher designs were independently verified with Surf3d, a method-of-moments based software. Additionally, the corresponding mirror system for
Mechanical Design of a Second Generation LHC IR Quadrupole
Caspi, S.; Bartlett, S.E.; Dietderich, D.R.; Ferracin, P.; Gourlay, S.A.; Hafalia, R.R.; Hannaford, C.R.; Lietzke, A.F.; McInturff,A.D.; Sabbi, G.; Scanlan, R.M.
2003-11-10
One of the proposed options to increase the LHC luminosity is the replacement of the existing inner triplets at the Interaction Regions with new low-beta larger aperture quadrupoles operating at the same gradient. Lawrence Berkeley National Laboratory (LBNL) is carrying out preliminary studies of a large-bore Nb{sub 3}Sn quadrupole. The mechanical design presents a support structure based on the use of keys and bladders without self-supporting collars. This technology has been proven effective in several successful common coil Nb{sub 3}Sn dipoles built at LBNL, and it is for the first time applied to a cos(2{var_theta}) design. In this paper we present a detailed analysis of the quadrupole mechanical behavior, demonstrating the possibility of delivering, through this method, well-controlled coil precompression during assembly, cool-down and excitation. The study has been performed with the finite element program ANSYS.
Mechanical Design of the HER Synchrotron Light Monitor Primary Mirror
Daly, Edward F.; Fisher, Alan S.; Kurita, Nadine R.; Langton, J.; /SLAC
2011-09-14
This paper describes the mechanical design of the primary mirror that images the visible portion of the synchrotron radiation (SR) extracted from the High Energy Ring (HER) of the PEP-II B-Factory. During off-axis operation, the water-cooled GlidCop mirror is subjected to a heat flux in excess of 2000 W/cm2. When on-axis imaging occurs, the heat flux due to scattered SR, resistive wall losses and Higher-Order-Mode (HOM) heating is estimated at 1 W/cm2. The imaging surface is plated with Electroless Nickel to improve its optical characteristics. The design requirements for the primary mirror are listed and discussed. Calculated mechanical distortions and stresses experienced by the mirror during on-axis and off-axis operation will be presented.
NASA Astrophysics Data System (ADS)
Craft, Michael J.; Buckner, Gregory D.; Anderson, Richard D.
2003-07-01
Automotive ride quality and handling performance remain challenging design tradeoffs for modern, passive automobile suspension systems. Despite extensive published research outlining the benefits of active vehicle suspensions in addressing this tradeoff, the cost and complexity of these systems frequently prohibit commercial adoption. Semi-active suspensions can provide performance benefits over passive suspensions without the cost and complexity associated with fully active systems. This paper outlines the development and experimental evaluation of a fuzzy logic control algorithm for a commercial semi-active suspension component, Carrera's MagneShockTM shock absorber. The MagneShockTM utilizes an electromagnet to change the viscosity of magnetorheological (MR) fluid, which changes the damping characteristics of the shock. Damping for each shock is controlled by manipulating the coil current using real-time algorithms. The performance capabilities of fuzzy logic control (FLC) algorithms are demonstrated through experimental evaluations on a passenger vehicle. Results show reductions of 25% or more in sprung mass absorbed power (U.S. Army 6 Watt Absorbed Power Criterion) as compared to typical passive shock absorbers over urban terrains in both simulation and experimentation. Average sprung-mass RMS accelerations were also reduced by as much as 9%, but usually with an increase in total suspension travel over the passive systems. Additionally, a negligible decrease in RMS tire normal force was documented through computer simulations. And although the FLC absorbed power was comparable to that of the fixed-current MagneShockTM the FLC revealed reduced average RMS sprung-mass accelerations over the fixed-current MagneShocks by 2-9%. Possible means for improvement of this system include reducing the suspension spring stiffness and increasing the dynamic damping range of the MagneShockTM.
Design principles of a rotating medium speed mechanism
NASA Technical Reports Server (NTRS)
Hostenkamp, R. G.; Achtermann, E.; Bentall, R. H.
1976-01-01
Design principles of a medium speed mechanism (MSM) are presented, including discussion on the relative merits of beryllium and aluminium as structural materials. Rotating at a speed of 60 rpm, the application envisaged for the MSM was as a despin bearing for the despun platform or despun antenna of a spin stabilized satellite. The MSM was built and tested to qualification level and is currently undergoing real time life testing.
POMM: design of rotating mechanism and hexapod structure
NASA Astrophysics Data System (ADS)
Côté, Patrice; Leclerc, Mélanie; Demers, Mathieu; Bastien, Pierre; Hernandez, Olivier
2014-08-01
The new high precision polarimeter for the "Observatoire du Mont Mégantic" (POMM) is an instrument designed to observe exoplanets and other targets in the visible and near infrared wavebands. The requirements to achieve these observation goals are posing unusual challenges to structural and mechanical designers. In this paper, the detailed design, analysis and laboratory results of the key mechanical structure and sub-systems are presented. First, to study extremely low polarization, the birefringence effect due to stresses in the optical elements must be kept to the lowest possible values. The double-wedge Wollaston custom prism assembly that splits the incoming optical beam is made of bonded α-BBO to N-BK-7 glass lenses. Because of the large mismatch of coefficients of thermal expansion and temperatures as low as -40°C that can be encountered at Mont-Mégantic observatory, a finite element analysis (FEA) model is developed to find the best adhesive system to minimize stresses. Another critical aspect discussed in details is the implementation of the cascaded rotating elements and the twin rotating stages. Special attention is given to the drive mechanism and encoding technology. The objective was to reach high absolute positional accuracy in rotation without any mechanical backlash. As for many other instruments, mass, size and dimensional stability are important critera for the supporting structure. For a cantilevered device, such as POMM, a static hexapod is an attractive solution because of the high stiffness to weight ratio. However, the mechanical analysis revealed that the specific geometry of the dual channel optical layout also added an off-axis counterbalancing problem. To reach an X-Y displacement error on the detector smaller than 35μm for 0-45° zenith angle, further structural optimization was done using FEA. An imaging camera was placed at the detector plane during assembly to measure the actual optical beam shift under varying gravitational
Design and performance of a cryogenic iris aperture mechanism
NASA Astrophysics Data System (ADS)
de Jonge, C.; Laauwen, W. M.; de Vries, E. A.; Smit, H. P.; Detrain, A.; Eggens, M. J.; Ferrari, L.; Dieleman, P.
2014-07-01
A cryogenic iris mechanism is under development as part of the ground calibration source for the SAFARI instrument. The iris mechanism is a variable aperture used as an optical shutter to fine-tune and modulate the absolute power output of the calibration source. It has 4 stainless steel blades that create a near-circular aperture in every position. The operating temperature is 4.5 Kelvin to provide a negligible background to the SAFARI detectors, and `hot spots' above 9K should be prevented. Cryogenic testing proved that the iris works at 4K. It can be used in a broad range of cryogenic optical instruments where optical throughput needs to be controlled. Challenges in the design include the low cooling power available (5mW) and low friction at cryogenic temperatures. The actuator is an `arc-type' rotary voice-coil motor. The use of flexural pivots creates a mono-stable mechanism with a resonance frequency at 26Hz. Accurate and fast position control with disturbance rejection is managed by a PID servo loop using a hall-sensor as input. At 4 Kelvin, the frequency is limited to 4Hz to avoid excess dissipation and heating. In this paper, the design and performance of the iris are discussed. The design was optimized using a thermal, magnetic and mechanical model made with COMSOL Finite Element Analysis software. The dynamical and state-space modeling of the mechanism and the concept of the electrical control are presented. The performance of the iris show good agreement to the analytical and COMSOL modeling.
Design and Development of NEA Scout Solar Sail Deployer Mechanism
NASA Technical Reports Server (NTRS)
Sobey, Alexander R.; Lockett, Tiffany Russell
2016-01-01
The 6U (approx.10 cm x 20 cm x 30 cm) cubesat Near Earth Asteroid (NEA) Scout1, projected for launch in September 2018 aboard the maiden voyage of the Space Launch System, will utilize a solar sail as its main method of propulsion throughout its approx.3-year mission to a Near Earth Asteroid. Due to the extreme volume constraints levied onto the mission, an acutely compact solar sail deployment mechanism has been designed to meet the volume and mass constraints, as well as provide enough propulsive solar sail area and quality in order to achieve mission success. The design of such a compact system required the development of approximately half a dozen prototypes in order to identify unforeseen problems, advance solutions, and build confidence in the final design product. This paper focuses on the obstacles of developing a solar sail deployment mechanism for such an application and the lessons learned from a thorough development process. The lessons presented will have significant applications beyond the NEA Scout mission, such as the development of other deployable boom mechanisms and uses for gossamer-thin films in space.
Design and Development of NEA Scout Solar Sail Deployer Mechanism
NASA Technical Reports Server (NTRS)
Sobey, Alexander R.; Lockett, Tiffany Russell
2016-01-01
The 6U (approximately 10cm x 20cm x 30cm) cubesat Near Earth Asteroid (NEA) Scout1, projected for launch in September 2018 aboard the maiden voyage of the Space Launch System (SLS), will utilize a solar sail as its main method of propulsion throughout its approximately 3 year mission to a Near Earth Asteroid (NEA). Due to the extreme volume constraints levied onto the mission, an acutely compact solar sail deployment mechanism has been designed to meet the volume and mass constraints, as well as provide enough propulsive solar sail area and quality in order to achieve mission success. The design of such a compact system required the development of approximately half a dozen prototypes in order to identify unforeseen problems, advance solutions, and build confidence in the final design product. This paper focuses on the obstacles of developing a solar sail deployment mechanism for such an application and the lessons learned from a thorough development process. The lessons presented will have significant applications beyond the NEA Scout mission, such as the development of other deployable boom mechanisms and uses for gossamer-thin films in space.
Convergent evolution in mechanical design of lamnid sharks and tunas.
Donley, Jeanine M; Sepulveda, Chugey A; Konstantinidis, Peter; Gemballa, Sven; Shadwick, Robert E
2004-05-01
The evolution of 'thunniform' body shapes in several different groups of vertebrates, including whales, ichthyosaurs and several species of large pelagic fishes supports the view that physical and hydromechanical demands provided important selection pressures to optimize body design for locomotion during vertebrate evolution. Recognition of morphological similarities between lamnid sharks (the most well known being the great white and the mako) and tunas has led to a general expectation that they also have converged in their functional design; however, no quantitative data exist on the mechanical performance of the locomotor system in lamnid sharks. Here we examine the swimming kinematics, in vivo muscle dynamics and functional morphology of the force-transmission system in a lamnid shark, and show that the evolutionary convergence in body shape and mechanical design between the distantly related lamnids and tunas is much more than skin deep; it extends to the depths of the myotendinous architecture and the mechanical basis for propulsive movements. We demonstrate that not only have lamnids and tunas converged to a much greater extent than previously known, but they have also developed morphological and functional adaptations in their locomotor systems that are unlike virtually all other fishes. PMID:15129279
Hou, Yongchao; Zhao, Yang
2015-01-01
A novel 3-PUU parallel robot was put forward, on which kinematic analysis was conducted to obtain its inverse kinematics solution, and on this basis, the limitations of the sliding pair and the Hooke joint on the workspace were analyzed. Moreover, the workspace was solved through the three dimensional limit search method, and then optimization analysis was performed on the workspace of this parallel robot, which laid the foundations for the configuration design and further analysis of the parallel mechanism, with the result indicated that this type of robot was equipped with promising application prospect. In addition that, the workspace after optimization can meet more requirements of patients. PMID:26628930
Hou, Yongchao; Zhao, Yang
2015-01-01
A novel 3-PUU parallel robot was put forward, on which kinematic analysis was conducted to obtain its inverse kinematics solution, and on this basis, the limitations of the sliding pair and the Hooke joint on the workspace were analyzed. Moreover, the workspace was solved through the three dimensional limit search method, and then optimization analysis was performed on the workspace of this parallel robot, which laid the foundations for the configuration design and further analysis of the parallel mechanism, with the result indicated that this type of robot was equipped with promising application prospect. In addition that, the workspace after optimization can meet more requirements of patients. PMID:26628930
A new blind fault component separation algorithm for a single-channel mechanical signal mixture
NASA Astrophysics Data System (ADS)
Wang, Dong; Tse, Peter W.
2012-10-01
A vibration signal collected from a complex machine consists of multiple vibration components, which are system responses excited by several sources. This paper reports a new blind component separation (BCS) method for extracting different mechanical fault features. By applying the proposed method, a single-channel mixed signal can be decomposed into two parts: the periodic and transient subsets. The periodic subset is related to the imbalance, misalignment and eccentricity of a machine. The transient subset refers to abnormal impulsive phenomena, such as those caused by localized bearing faults. The proposed method includes two individual strategies to deal with these different characteristics. The first extracts the sub-Gaussian periodic signal by minimizing the kurtosis of the equalized signals. The second detects the super-Gaussian transient signal by minimizing the smoothness index of the equalized signals. Here, the equalized signals are derived by an eigenvector algorithm that is a successful solution to the blind equalization problem. To reduce the computing time needed to select the equalizer length, a simple optimization method is introduced to minimize the kurtosis and smoothness index, respectively. Finally, simulated multiple-fault signals and a real multiple-fault signal collected from an industrial machine are used to validate the proposed method. The results show that the proposed method is able to effectively decompose the multiple-fault vibration mixture into periodic components and random non-stationary transient components. In addition, the equalizer length can be intelligently determined using the proposed method.
Design and Development of NEA Scout Solar Sail Deployer Mechanism
NASA Technical Reports Server (NTRS)
Sobey, Alexander R.; Lockett, Tiffany Russell
2016-01-01
The 6U (approximately10cm x 20cm x 30cm) cubesat Near Earth Asteroid (NEA) Scout, projected for launch in September 2018 aboard the maiden voyage of the Space Launch System (SLS), will utilize a solar sail as its main method of propulsion throughout its approximately 3 year mission to a near earth asteroid. Due to the extreme volume constraints levied onto the mission, an acutely compact solar sail deployment mechanism has been designed to meet the volume and mass constraints, as well as provide enough propulsive solar sail area and quality in order to achieve mission success. The design of such a compact system required the development of approximately half a dozen prototypes in order to identify unforeseen problems and advance solutions. Though finite element analysis was performed during this process in an attempt to quantify forces present within the mechanism during deployment, both the boom and the sail materials do not lend themselves to achieving high-confidence results. This paper focuses on the obstacles of developing a solar sail deployment mechanism for such an application and the lessons learned from a thorough development process. The lessons presented here will have significant applications beyond the NEA Scout mission, such as the development of other deployable boom mechanisms and uses for gossamer-thin films in space.
Frida integral field unit opto-mechanical design
NASA Astrophysics Data System (ADS)
Cuevas, Salvador; Eikenberry, Stephen S.; Bringas, Vicente; Corrales, Adi; Espejo, Carlos; Lucero, Diana; Rodriguez, Alberto; Sánchez, Beatriz; Uribe, Jorge
2012-09-01
FRIDA (inFRared Imager and Dissector for the Adaptive optics system of the Gran Telescopio Canarias) has been designed as a cryogenic and diffraction limited instrument that will offer broad and narrow band imaging and integral field spectroscopy (IFS). Both, the imaging mode and IFS observing modes will use the same Teledyne 2Kx2K detector. This instrument will be installed at Nasmyth B station, behind the GTC Adaptive Optics system. FRIDA will provide the IFS mode using a 30 slices Integral Field Unit (IFU). This IFU design is based on University of Florida FISICA where the mirror block arrays are diamond turned on monolithic metal blocks. FRIDA IFU is conformed mainly by 3 mirror blocks with 30 spherical mirrors each. It also has a Schwarzschild relay based on two off axis spherical mirrors and an afocal system of two parabolic off axis mirrors. Including two insertion mirrors the IFU holds 96 metal mirrors. Each block or individual mirror is attached on its own mechanical mounting. In order to study beam interferences with mechanical parts, ghosts and scattered light, an iterative optical-mechanical modeling was developed. In this work this iterative modeling is described including pictures showing actual ray tracing on the opto-mechanical components.
NASA Astrophysics Data System (ADS)
Baadache, Khireddine; Bougriou, Chérif
2015-10-01
This paper presents the use of Genetic Algorithm in the sizing of the shell and double concentric tube heat exchanger where the objective function is the total cost which is the sum of the capital cost of the device and the operating cost. The use of the techno-economic methods based on the optimisation methods of heat exchangers sizing allow to have a device that satisfies the technical specification with the lowest possible levels of operating and investment costs. The logarithmic mean temperature difference method was used for the calculation of the heat exchange area. This new heat exchanger is more profitable and more economic than the old heat exchanger, the total cost decreased of about 13.16 % what represents 7,250.8 euro of the lump sum. The design modifications and the use of the Genetic Algorithm for the sizing also allow to improve the compactness of the heat exchanger, the study showed that the latter can increase the heat transfer surface area per unit volume until 340 m2/m3.
Design of Clinical Support Systems Using Integrated Genetic Algorithm and Support Vector Machine
NASA Astrophysics Data System (ADS)
Chen, Yung-Fu; Huang, Yung-Fa; Jiang, Xiaoyi; Hsu, Yuan-Nian; Lin, Hsuan-Hung
Clinical decision support system (CDSS) provides knowledge and specific information for clinicians to enhance diagnostic efficiency and improving healthcare quality. An appropriate CDSS can highly elevate patient safety, improve healthcare quality, and increase cost-effectiveness. Support vector machine (SVM) is believed to be superior to traditional statistical and neural network classifiers. However, it is critical to determine suitable combination of SVM parameters regarding classification performance. Genetic algorithm (GA) can find optimal solution within an acceptable time, and is faster than greedy algorithm with exhaustive searching strategy. By taking the advantage of GA in quickly selecting the salient features and adjusting SVM parameters, a method using integrated GA and SVM (IGS), which is different from the traditional method with GA used for feature selection and SVM for classification, was used to design CDSSs for prediction of successful ventilation weaning, diagnosis of patients with severe obstructive sleep apnea, and discrimination of different cell types form Pap smear. The results show that IGS is better than methods using SVM alone or linear discriminator.
NASA Astrophysics Data System (ADS)
Masoumi, Massoud; Raissi, Farshid; Ahmadian, Mahmoud; Keshavarzi, Parviz
2006-01-01
We are proposing that the recently proposed semiconductor-nanowire-molecular architecture (CMOL) is an optimum platform to realize encryption algorithms. The basic modules for the advanced encryption standard algorithm (Rijndael) have been designed using CMOL architecture. The performance of this design has been evaluated with respect to chip area and speed. It is observed that CMOL provides considerable improvement over implementation with regular CMOS architecture even with a 20% defect rate. Pseudo-optimum gate placement and routing are provided for Rijndael building blocks and the possibility of designing high speed, attack tolerant and long key encryptions are discussed.
NASA Technical Reports Server (NTRS)
Burt, Adam O.; Tinker, Michael L.
2014-01-01
In this paper, genetic algorithm based and gradient-based topology optimization is presented in application to a real hardware design problem. Preliminary design of a planetary lander mockup structure is accomplished using these methods that prove to provide major weight savings by addressing the structural efficiency during the design cycle. This paper presents two alternative formulations of the topology optimization problem. The first is the widely-used gradient-based implementation using commercially available algorithms. The second is formulated using genetic algorithms and internally developed capabilities. These two approaches are applied to a practical design problem for hardware that has been built, tested and proven to be functional. Both formulations converged on similar solutions and therefore were proven to be equally valid implementations of the process. This paper discusses both of these formulations at a high level.
Mechanical design problems associated with turbopump fluid film bearings
NASA Technical Reports Server (NTRS)
Evces, Charles R.
1990-01-01
Most high speed cryogenic turbopumps for liquid propulsion rocket engines currently use ball or roller contact bearings for rotor support. The operating speeds, loads, clearances, and environments of these pumps combine to make bearing wear a limiting factor on turbopump life. An example is the high pressure oxygen turbopump (HPOTP) used in the Space Shuttle Main Engine (SSME). Although the HPOTP design life is 27,000 seconds at 30,000 rpms, or approximately 50 missions, bearings must currently be replaced after 2 missions. One solution to the bearing wear problem in the HPOTP, as well as in future turbopump designs, is the utilization of fluid film bearings in lieu of continuous contact bearings. Hydrostatic, hydrodynamic, and damping seal bearings are all replacement candidates for contact bearings in rocket engine high speed turbomachinery. These three types of fluid film bearings have different operating characteristics, but they share a common set of mechanical design opportunities and difficulties. Results of research to define some of the mechanical design issues are given. Problems considered include transient strat/stop rub, non-operational rotor support, bearing wear inspection and measurement, and bearing fluid supply route. Emphasis is given to the HPOTP preburner pump (PBP) bearing, but the results are pertinent to high-speed cryogenic turbomachinery in general.
Mechanical design of the WIYN One Degree Imager (ODI)
NASA Astrophysics Data System (ADS)
Muller, Gary P.; Harbeck, Daniel; Jacoby, George H.; Harmer, Charles; Yeatts, Andrey; Blanco, Dan; Cavin, John; Sawyer, Dave
2008-07-01
The WIYN consortium is building the One Degree Imager (ODI) to be mounted to a Nasmyth port of the WIYN 3.5m telescope, located at Kitt Peak, Arizona, USA). ODI will utilize both the excellent image quality and the one-degree field of view that the telescope delivers. To accommodate the large field of view (~0.39m diameter unvignetted field with 0.54m across the diagonal of the one-degree-square, partially vignetted field), 0.6m-class optics are required. The ODI design consists of a two element corrector: one serves as a vacuum barrier to the cryostat, the other is an asphere; two independently rotating bonded prism pairs for atmospheric dispersion compensation (ADC); nine independently deployable filters via a simple pivoting motion; and a 971 mega-pixel focal plane consisting of 64 orthogonal transfer array (OTA) devices. This paper is an overview of the mechanical design of ODI and describes the optical element mounting and alignment strategy, the ADC & filter mechanisms, plus the focal plane. Additionally, the project status will be discussed. In accompanying papers Jacoby1 describes ODI's optical design, Yeatts2 describes the software and control system design, and Harbeck3 gives a general update on the project.
Functional Design in Rehabilitation: Modular Mechanisms for Ankle Complex
2016-01-01
This paper is aimed at presenting an innovative ankle rehabilitation device based on a parallel mechanism. A functional analysis and design are described to obtain a device able to guarantee ankle movement while patient's body remains stationary. Human ankle is a challenging context where a series of joints are highly integrated. The proposed rehabilitation device permits a patient with walking defects to improve his or her gait. The research focuses on plantar-flexion-dorsiflexion movement. The robust design starts from an accurate modelling of ankle movements during walking, assessing motion data from healthy individuals and patients. The kinematics analysis and functional evaluations lead the study and development of the articulated system. In particular, results of simulations support the effectiveness of the current design. A 3D prototype is presented highlighting that the ankle motion is successfully demonstrated. PMID:27524881
Mechanical design of a large bore quadrupole triplet magnet
Abbott, S.; Caylor, R.; Fong, E.; Tanabe, J.
1987-03-01
The mechanical design and construction of a 1 meter bore, low gradient quadrupole triplet is described. The magnet will be used for focussing a proton beam in accelerator studies of neutral particle at the Los Alamos National Laboratory. A significant feature of this magnet design is the precision location of the coil conductors within the steel yoke tube. Each of the quadrupole coils have been fabricated from water cooled aluminum conductor, wound in a cosine 2-theta geometry. The conductor bundles have been wound to a positional accuracy within +-0.050 cm which was required to reduce the harmonic content to less than 0.04% of the quadrupole field. Important aspects of the design, construction and assembly are described.
Towards designing an optical-flow based colonoscopy tracking algorithm: a comparative study
NASA Astrophysics Data System (ADS)
Liu, Jianfei; Subramanian, Kalpathi R.; Yoo, Terry S.
2013-03-01
Automatic co-alignment of optical and virtual colonoscopy images can supplement traditional endoscopic procedures, by providing more complete information of clinical value to the gastroenterologist. In this work, we present a comparative analysis of our optical flow based technique for colonoscopy tracking, in relation to current state of the art methods, in terms of tracking accuracy, system stability, and computational efficiency. Our optical-flow based colonoscopy tracking algorithm starts with computing multi-scale dense and sparse optical flow fields to measure image displacements. Camera motion parameters are then determined from optical flow fields by employing a Focus of Expansion (FOE) constrained egomotion estimation scheme. We analyze the design choices involved in the three major components of our algorithm: dense optical flow, sparse optical flow, and egomotion estimation. Brox's optical flow method,1 due to its high accuracy, was used to compare and evaluate our multi-scale dense optical flow scheme. SIFT6 and Harris-affine features7 were used to assess the accuracy of the multi-scale sparse optical flow, because of their wide use in tracking applications; the FOE-constrained egomotion estimation was compared with collinear,2 image deformation10 and image derivative4 based egomotion estimation methods, to understand the stability of our tracking system. Two virtual colonoscopy (VC) image sequences were used in the study, since the exact camera parameters(for each frame) were known; dense optical flow results indicated that Brox's method was superior to multi-scale dense optical flow in estimating camera rotational velocities, but the final tracking errors were comparable, viz., 6mm vs. 8mm after the VC camera traveled 110mm. Our approach was computationally more efficient, averaging 7.2 sec. vs. 38 sec. per frame. SIFT and Harris affine features resulted in tracking errors of up to 70mm, while our sparse optical flow error was 6mm. The comparison
Cold header machine process monitoring using a genetic algorithm designed neural network approach
NASA Astrophysics Data System (ADS)
dos Reis, Henrique L. M.; Voegele, Aaron C.; Cook, David B.
1999-12-01
In cold heading manufacturing processes, complete or partial fracture of the punch-pin leads to production of out-of-tolerance parts. A process monitoring system has been developed to assure that out-of-tolerance parts do not contaminate the batch of acceptable parts. A four-channel data acquisition system was assembled to collect and store the acoustic signal generated during the manufacturing process. A genetic algorithm was designed to select the smallest subset of waveform features necessary to develop a robust artificial neural network that could differentiate among the various cold head machine conditions, including complete or partial failure of the punch pin. The developed monitoring system is able to terminate production within seconds of punch pin failure using only four waveform features.
Optimum design of vortex generator elements using Kriging surrogate modelling and genetic algorithm
NASA Astrophysics Data System (ADS)
Neelakantan, Rithwik; Balu, Raman; Saji, Abhinav
Vortex Generators (VG's) are small angled plates located in a span wise fashion aft of the leading edge of an aircraft wing. They control airflow over the upper surface of the wing by creating vortices which energise the boundary layer. The parameters considered for the optimisation study of the VG's are its height, orientation angle and location along the chord in a low subsonic flow over a NACA0012 airfoil. The objective function to be maximised is the L/D ratio of the airfoil. The design data are generated using the commercially available ANSYS FLUENT software and are modelled using a Kriging based interpolator. This surrogate model is used along with a Generic Algorithm software to arrive at the optimum shape of the VG's. The results of this study will be confirmed with actual wind tunnel tests on scaled models.
Design of Pipeline Multiplier Based on Modified Booth's Algorithm and Wallace Tree
NASA Astrophysics Data System (ADS)
Yao, Aihong; Li, Ling; Sun, Mengzhe
A design of 32*32 bit pipelined multiplier is presented in this paper. The proposed multiplier is based on the modified booth algorithm and Wallace tree structure. In order to improve the throughput rate of the multiplier, pipeline architecture is introduced to the Wallace tree. Carry Select Adder is deployed to reduce the propagation delay of carry signal for the final level 64-bit adder. The multiplier is fully implemented with Verilog HDL and synthesized successfully with Quartus II. The experiment result shows that the resource consumption and power consumption is reduced to 2560LE and 120mW, the operating frequency is improved from 136.21MHz to 165.07MHz.
Designing Integrated Fuzzy Guidance Law for Aerodynamic Homing Missiles Using Genetic Algorithms
NASA Astrophysics Data System (ADS)
Omar, Hanafy M.
The Fuzzy logic controller (FLC) is well-known for robustness to parameter variations and ability to reject noise. However, its design requires definition of many parameters. This work proposes a systematic and simple procedure to develop an integrated fuzzy-based guidance law which consists of three FLC. Each is activated in a region of the interception. Another fuzzy-based switching system is introduced to allow smooth transition between these controllers. The parameters of all the fuzzy controllers, which include the distribution of the membership functions and the rules, are obtained simply by observing the function of each controller. Furthermore, these parameters are tuned by genetic algorithms by solving an optimization problem to minimize the interception time, missile acceleration commands, and miss distance. The simulation results show that the proposed procedure can generate a guidance law with satisfactory performance.
Designing Daily Patrol Routes for Policing Based on ANT Colony Algorithm
NASA Astrophysics Data System (ADS)
Chen, H.; Cheng, T.; Wise, S.
2015-07-01
In this paper, we address the problem of planning police patrol routes to regularly cover street segments of high crime density (hotspots) with limited police forces. A good patrolling strategy is required to minimise the average time lag between two consecutive visits to hotspots, as well as coordinating multiple patrollers and imparting unpredictability in patrol routes. Previous studies have designed different police patrol strategies for routing police patrol, but these strategies have difficulty in generalising to real patrolling and meeting various requirements. In this research we develop a new police patrolling strategy based on Bayesian method and ant colony algorithm. In this strategy, virtual marker (pheromone) is laid to mark the visiting history of each crime hotspot, and patrollers continuously decide which hotspot to patrol next based on pheromone level and other variables. Simulation results using real data testifies the effective, scalable, unpredictable and extensible nature of this strategy.
NASA Technical Reports Server (NTRS)
Argentiero, P.; Garza-Robles, R.
1980-01-01
The extraction of brightness temperature maps from scanning radiometer data is described as a typical linear inverse problem. Spatial quantization and parameter estimation is described and is suggested as an advantageous approach to a solution. Since this approach takes into explicit account the multivariate nature of the problem, it permits an accurate determination of the most detailed resolution extractable from the data as well as explicitly defining the possible compromises between accuracy and resolution. To illustrate the usefulness of the method described for algorithm design and accuracy prediction, it was applied to the problem of providing brightness temperature maps during the NOSS flight segment. The most detained possible resolution was determined and a curve which displays the possible compromises between accuracy and resolution was provided.
Mechanical Design Engineering Enabler Project wheel and wheel drives
NASA Technical Reports Server (NTRS)
Nutt, Richard E.; Couch, Britt K.; Holley, John L., Jr.; Garris, Eric S.; Staut, Paul V.
1992-01-01
Our group was assigned the responsibility of designing the wheel and wheel drive system for a proof-of-concept model of the lunar-based ENABLER. ENABLER is a multi-purpose, six wheeled vehicle designed to lift and transport heavy objects associated with the construction of a lunar base. The resulting design was based on the performance criteria of the ENABLER. The drive system was designed to enable the vehicle to achieve a speed of 7 mph on a level surface, climb a 30 percent grade, and surpass a one meter high object and one meter wide crevice. The wheel assemblies were designed to support the entire weight of the vehicle on two wheels. The wheels were designed to serve as the main component of the vehicle's suspension and will provide suitable traction for lunar-type surfaces. The expected performance of the drive system for the ENABLER was influenced by many mechanical factors. The expected top speed on a level sandy surface is 4 mph instead of the desired 7 mph. This is due to a lack of necessary power at the wheels. The lack of power resulted from dimension considerations that allowed only an eight horsepower engine and also from mechanical inefficiencies of the hydraulic system. However, the vehicle will be able to climb a 30 percent grade, surpass a one meter high object and one meter wide crevice. The wheel assemblies will be able to support the entire weight of the vehicle on two wheels. The wheels will also provide adequate suspension for the vehicle and sufficient traction for lunar-type surfaces.
Design of a gradient-index beam shaping system via a genetic algorithm optimization method
NASA Astrophysics Data System (ADS)
Evans, Neal C.; Shealy, David L.
2000-10-01
Geometrical optics - the laws of reflection and refraction, ray tracing, conservation of energy within a bundle of rays, and the condition of constant optical path length - provides a foundation for design of laser beam shaping systems. This paper explores the use of machine learning techniques, concentrating on genetic algorithms, to design laser beam shaping systems using geometrical optics. Specifically, a three-element GRIN laser beam shaping system has been designed to expand and transform a Gaussian input beam profile into one with a uniform irradiance profile. Solution to this problem involves the constrained optimization of a merit function involving a mix of discrete and continuous parameters. The merit function involves terms that measure the deviation of the output beam diameter, divergence, and irradiance from target values. The continuous parameters include the distances between the lens elements, the thickness, and radii of the lens elements. The discrete parameters include the GRIN glass types from a manufacturer's database, the gradient direction of the GRIN elements (positive or negative), and the actual number of lens elements in the system (one to four).
Chen, Kun-Huang; Wang, Kung-Jeng; Adrian, Angelia Melani; Wang, Kung-Min; Teng, Nai-Chia
2016-01-01
Brain metastases are commonly found in patients that are diagnosed with primary malignancy on their lung. Lung cancer patients with brain metastasis tend to have a poor survivability, which is less than 6 months in median. Therefore, an early and effective detection system for such disease is needed to help prolong the patients' survivability and improved their quality of life. A modified electromagnetism-like mechanism (EM) algorithm, MEM-SVM, is proposed by combining EM algorithm with support vector machine (SVM) as the classifier and opposite sign test (OST) as the local search technique. The proposed method is applied to 44 UCI and IDA datasets, and 5 cancers microarray datasets as preliminary experiment. In addition, this method is tested on 4 lung cancer microarray public dataset. Further, we tested our method on a nationwide dataset of brain metastasis from lung cancer (BMLC) in Taiwan. Since the nature of real medical dataset to be highly imbalanced, the synthetic minority over-sampling technique (SMOTE) is utilized to handle this problem. The proposed method is compared against another 8 popular benchmark classifiers and feature selection methods. The performance evaluation is based on the accuracy and Kappa index. For the 44 UCI and IDA datasets and 5 cancer microarray datasets, a non-parametric statistical test confirmed that MEM-SVM outperformed the other methods. For the 4 lung cancer public microarray datasets, MEM-SVM still achieved the highest mean value for accuracy and Kappa index. Due to the imbalanced property on the real case of BMLC dataset, all methods achieve good accuracy without significance difference among the methods. However, on the balanced BMLC dataset, MEM-SVM appears to be the best method with higher accuracy and Kappa index. We successfully developed MEM-SVM to predict the occurrence of brain metastasis from lung cancer with the combination of SMOTE technique to handle the class imbalance properties. The results confirmed that MEM
David J. Muth Jr.
2006-09-01
This paper examines the use of graph based evolutionary algorithms (GBEAs) to find multiple acceptable solutions for heat transfer in engineering systems during the optimization process. GBEAs are a type of evolutionary algorithm (EA) in which a topology, or geography, is imposed on an evolving population of solutions. The rates at which solutions can spread within the population are controlled by the choice of topology. As in nature geography can be used to develop and sustain diversity within the solution population. Altering the choice of graph can create a more or less diverse population of potential solutions. The choice of graph can also affect the convergence rate for the EA and the number of mating events required for convergence. The engineering system examined in this paper is a biomass fueled cookstove used in developing nations for household cooking. In this cookstove wood is combusted in a small combustion chamber and the resulting hot gases are utilized to heat the stove’s cooking surface. The spatial temperature profile of the cooking surface is determined by a series of baffles that direct the flow of hot gases. The optimization goal is to find baffle configurations that provide an even temperature distribution on the cooking surface. Often in engineering, the goal of optimization is not to find the single optimum solution but rather to identify a number of good solutions that can be used as a starting point for detailed engineering design. Because of this a key aspect of evolutionary optimization is the diversity of the solutions found. The key conclusion in this paper is that GBEA’s can be used to create multiple good solutions needed to support engineering design.
NASA Astrophysics Data System (ADS)
Montoya Villena, Rafael
According to its title, the general objective of the Thesis consists in developing a clear, simple and systematic methodology for programming type PLC devices. With this aim in mind, we will use the following elements: Codification of all variables types. This section is very important since it allows us working with little information. The necessary rules are given to codify all type of phrases produced in industrial processes. An algorithm that describes process evolution and that has been called process D.F. This is one of the most important contributions, since it will allow us, together with information codification, representing the process evolution in a graphic way and with any design theory used. Theory selection. Evidently, the use of some kind of design method is necessary to obtain logic equations. For this particular case, we will use binodal theory, an ideal theory for wired technologies, since it can obtain highly reduced schemas for relatively simple automatisms, which means a minimum number of components used. User program outline algorithm (D.F.P.). This is another necessary contribution and perhaps the most important one, since logic equations resulting from binodal theory are compatible with process evolution if wired technology is used, whether it is electric, electronic, pneumatic, etc. On the other hand, PLC devices performance characteristics force the program instructions order to validate or not the automatism, as we have proven in different articles and lectures at congresses both national and international. Therefore, we will codify any information concerning the automating process, graphically represent its temporal evolution and, applying binodal theory and D.F.P (previously adapted), succeed in making logic equations compatible with the process to be automated and the device in which they will be implemented (PLC in our case)
Evolutionary Design of one-dimensional Rule Changing cellular automata using genetic algorithms
NASA Astrophysics Data System (ADS)
Yun, Wu; Kanoh, Hitoshi
In this paper we propose a new method to obtain transition rules of one-dimensional two-state cellular automata (CAs) using genetic algorithms (GAs). CAs have the advantages of producing complex systems from the interaction of simple elements, and have attracted increased research interest. However, the difficulty of designing CAs' transition rules to perform a particular task has severely limited their applications. The evolutionary design of CA rules has been studied by the EVCA group in detail. A GA was used to evolve CAs for two tasks: density classification and synchronization problems. That GA was shown to have discovered rules that gave rise to sophisticated emergent computational strategies. Sipper has studied a cellular programming algorithm for 2-state non-uniform CAs, in which each cell may contain a different rule. Meanwhile, Land and Belew proved that the perfect two-state rule for performing the density classification task does not exist. However, Fuks´ showed that a pair of human written rules performs the task perfectly when the size of neighborhood is one. In this paper, we consider a pair of rules and the number of rule iterations as a chromosome, whereas the EVCA group considers a rule as a chromosome. The present method is meant to reduce the complexity of a given problem by dividing the problem into smaller ones and assigning a distinct rule to each one. Experimental results for the two tasks prove that our method is more efficient than a conventional method. Some of the obtained rules agree with the human written rules shown by Fuks´. We also grouped 1000 rules with high fitness into 4 classes according to the Langton's λ parameter. The rules obtained by the proposed method belong to Class- I, II, III or IV, whereas most of the rules by the conventional method belong to Class-IV only. This result shows that the combination of simple rules can perform complex tasks.
Afanasyev, Vsevolod; Buldyrev, Sergey V.; Dunn, Michael J.; Robst, Jeremy; Preston, Mark; Bremner, Steve F.; Briggs, Dirk R.; Brown, Ruth; Adlard, Stacey; Peat, Helen J.
2015-01-01
A fully automated weighbridge using a new algorithm and mechanics integrated with a Radio Frequency Identification System is described. It is currently in use collecting data on Macaroni penguins (Eudyptes chrysolophus) at Bird Island, South Georgia. The technology allows researchers to collect very large, highly accurate datasets of both penguin weight and direction of their travel into or out of a breeding colony, providing important contributory information to help understand penguin breeding success, reproductive output and availability of prey. Reliable discrimination between single and multiple penguin crossings is demonstrated. Passive radio frequency tags implanted into penguins allow researchers to match weight and trip direction to individual birds. Low unit and operation costs, low maintenance needs, simple operator requirements and accurate time stamping of every record are all important features of this type of weighbridge, as is its proven ability to operate 24 hours a day throughout a breeding season, regardless of temperature or weather conditions. Users are able to define required levels of accuracy by adjusting filters and raw data are automatically recorded and stored allowing for a range of processing options. This paper presents the underlying principles, design specification and system description, provides evidence of the weighbridge’s accurate performance and demonstrates how its design is a significant improvement on existing systems. PMID:25894763
Afanasyev, Vsevolod; Buldyrev, Sergey V; Dunn, Michael J; Robst, Jeremy; Preston, Mark; Bremner, Steve F; Briggs, Dirk R; Brown, Ruth; Adlard, Stacey; Peat, Helen J
2015-01-01
A fully automated weighbridge using a new algorithm and mechanics integrated with a Radio Frequency Identification System is described. It is currently in use collecting data on Macaroni penguins (Eudyptes chrysolophus) at Bird Island, South Georgia. The technology allows researchers to collect very large, highly accurate datasets of both penguin weight and direction of their travel into or out of a breeding colony, providing important contributory information to help understand penguin breeding success, reproductive output and availability of prey. Reliable discrimination between single and multiple penguin crossings is demonstrated. Passive radio frequency tags implanted into penguins allow researchers to match weight and trip direction to individual birds. Low unit and operation costs, low maintenance needs, simple operator requirements and accurate time stamping of every record are all important features of this type of weighbridge, as is its proven ability to operate 24 hours a day throughout a breeding season, regardless of temperature or weather conditions. Users are able to define required levels of accuracy by adjusting filters and raw data are automatically recorded and stored allowing for a range of processing options. This paper presents the underlying principles, design specification and system description, provides evidence of the weighbridge's accurate performance and demonstrates how its design is a significant improvement on existing systems. PMID:25894763
Designing Crane Controls with applied Mechanical and Electrical Safety Features
NASA Technical Reports Server (NTRS)
Lytle, Bradford P.; Walczak, Thomas A.; Delgado, H. (Technical Monitor)
2002-01-01
The use of overhead traveling bridge cranes in many varied applications is common practice. In particular, the use of cranes in the nuclear, military, commercial, aerospace, and other industries can involve safety critical situations. Considerations for Human Injury or Casualty, Loss of Assets, Endangering the Environment, or Economic Reduction must be addressed. Traditionally, in order to achieve additional safety in these applications, mechanical systems have been augmented with a variety of devices. These devices assure that a mechanical component failure shall reduce the risk of a catastrophic loss of the correct and/or safe load carrying capability. ASME NOG-1-1998, (Rules for Construction of Overhead and Gantry Cranes, Top Running Bridge, and Multiple Girder), provides design standards for cranes in safety critical areas. Over and above the minimum safety requirements of todays design standards, users struggle with obtaining a higher degree of reliability through more precise functional specifications while attempting to provide "smart" safety systems. Electrical control systems also may be equipped with protective devices similar to the mechanical design features. Demands for improvement of the cranes "control system" is often recognized, but difficult to quantify for this traditionally "mechanically" oriented market. Finite details for each operation must be examined and understood. As an example, load drift (or small motions) at close tolerances can be unacceptable (and considered critical). To meet these high functional demands encoders and other devices are independently added to control systems to provide motion and velocity feedback to the control drive. This paper will examine the implementation of Programmable Electronic Systems (PES). PES is a term this paper will use to describe any control system utilizing any programmable electronic device such as Programmable Logic Controllers (PLC), or an Adjustable Frequency Drive (AID) 'smart' programmable
Optimum design of bolted composite lap joints under mechanical and thermal loading
NASA Astrophysics Data System (ADS)
Kradinov, Vladimir Yurievich
A new approach is developed for the analysis and design of mechanically fastened composite lap joints under mechanical and thermal loading. Based on the combined complex potential and variational formulation, the solution method satisfies the equilibrium equations exactly while the boundary conditions are satisfied by minimizing the total potential. This approach is capable of modeling finite laminate planform dimensions, uniform and variable laminate thickness, laminate lay-up, interaction among bolts, bolt torque, bolt flexibility, bolt size, bolt-hole clearance and interference, insert dimensions and insert material properties. Comparing to the finite element analysis, the robustness of the method does not decrease when modeling the interaction of many bolts; also, the method is more suitable for parametric study and design optimization. The Genetic Algorithm (GA), a powerful optimization technique for multiple extrema functions in multiple dimensions search spaces, is applied in conjunction with the complex potential and variational formulation to achieve optimum designs of bolted composite lap joints. The objective of the optimization is to acquire such a design that ensures the highest strength of the joint. The fitness function for the GA optimization is based on the average stress failure criterion predicting net-section, shear-out, and bearing failure modes in bolted lap joints. The criterion accounts for the stress distribution in the thickness direction at the bolt location by applying an approach utilizing a beam on an elastic foundation formulation.
Probabilistic Design Methodology and its Application to the Design of an Umbilical Retract Mechanism
NASA Astrophysics Data System (ADS)
Onyebueke, Landon; Ameye, Olusesan
2002-10-01
A lot has been learned from past experience with structural and machine element failures. The understanding of failure modes and the application of an appropriate design analysis method can lead to improved structural and machine element safety as well as serviceability. To apply Probabilistic Design Methodology (PDM), all uncertainties are modeled as random variables with selected distribution types, means, and standard deviations. It is quite difficult to achieve a robust design without considering the randomness of the design parameters which is the case in the use of the Deterministic Design Approach. The US Navy has a fleet of submarine-launched ballistic missiles. An umbilical plug joins the missile to the submarine in order to provide electrical and cooling water connections. As the missile leaves the submarine, an umbilical retract mechanism retracts the umbilical plug clear of the advancing missile after disengagement during launch and retrains the plug in the retracted position. The design of the current retract mechanism in use was based on the deterministic approach which puts emphasis on factor of safety. A new umbilical retract mechanism that is simpler in design, lighter in weight, more reliable, easier to adjust, and more cost effective has become desirable since this will increase the performance and efficiency of the system. This paper reports on a recent project performed at Tennessee State University for the US Navy that involved the application of PDM to the design of an umbilical retract mechanism. This paper demonstrates how the use of PDM lead to the minimization of weight and cost, and the maximization of reliability and performance.
Probabilistic Design Methodology and its Application to the Design of an Umbilical Retract Mechanism
NASA Technical Reports Server (NTRS)
Onyebueke, Landon; Ameye, Olusesan
2002-01-01
A lot has been learned from past experience with structural and machine element failures. The understanding of failure modes and the application of an appropriate design analysis method can lead to improved structural and machine element safety as well as serviceability. To apply Probabilistic Design Methodology (PDM), all uncertainties are modeled as random variables with selected distribution types, means, and standard deviations. It is quite difficult to achieve a robust design without considering the randomness of the design parameters which is the case in the use of the Deterministic Design Approach. The US Navy has a fleet of submarine-launched ballistic missiles. An umbilical plug joins the missile to the submarine in order to provide electrical and cooling water connections. As the missile leaves the submarine, an umbilical retract mechanism retracts the umbilical plug clear of the advancing missile after disengagement during launch and retrains the plug in the retracted position. The design of the current retract mechanism in use was based on the deterministic approach which puts emphasis on factor of safety. A new umbilical retract mechanism that is simpler in design, lighter in weight, more reliable, easier to adjust, and more cost effective has become desirable since this will increase the performance and efficiency of the system. This paper reports on a recent project performed at Tennessee State University for the US Navy that involved the application of PDM to the design of an umbilical retract mechanism. This paper demonstrates how the use of PDM lead to the minimization of weight and cost, and the maximization of reliability and performance.
Quantum-Mechanical Combinatorial Design of Solids with Target Properties
NASA Astrophysics Data System (ADS)
Zunger, Alex
2009-10-01
One of the most striking aspects of solid-state physics is the diversity of structural forms in which crystals appear in Nature. The already rich repertoire of such (equilibrium) forms has recently been significantly enriched by the advent of artificial growth techniques (MBE, STM- atom positioning, etc) that can create desired structural forms, such as superlattices and geometric atomic clusters even in defiance of the rules of equilibrium thermodynamics. As is well known, different atomic configurations generally lead to different physical properties even at fixed chemical composition. While the most widely-known illustration of such ``form controls function'' rule is the dramatically different color, conductivity and hardness of the allotropical forms of pure carbon, the physics of semiconductor superstructures and nanostructures is full of striking examples of how optical, magnetic and transport properties depend sensitively on atomic configuration (e.g, compare the properties of random to ordered alloys). Yet, the history of material research generally proceeded via accidental discoveries of materials configuration with interesting physical property (semiconductivity, ferromagnetism; superconductivity etc). Given the ability of growing many different atomic configurations, and given the often sensitive dependence of physical properties on atomic configuration, makes one wonder: can one first articulate the desired target physical property, then search (within a class) for the configuration that has this property? This talk describes the recent steps made by solid-state theory and computational physics to address this ``Inverse Design'' problem. I will show how Genetic Algorithms, in combination with efficient (``Order N'') solutions to the Pseudopotential Schr"odinger equation allow us to investigate astronomical spaces of atomic configurations in search of the structure with a target physical problem. Only a small fraction of all ( ˜10^14 in our case
Bornholdt, S.; Graudenz, D.
1993-07-01
A learning algorithm based on genetic algorithms for asymmetric neural networks with an arbitrary structure is presented. It is suited for the learning of temporal patterns and leads to stable neural networks with feedback.
RNAiFOLD: a constraint programming algorithm for RNA inverse folding and molecular design.
Garcia-Martin, Juan Antonio; Clote, Peter; Dotu, Ivan
2013-04-01
Synthetic biology is a rapidly emerging discipline with long-term ramifications that range from single-molecule detection within cells to the creation of synthetic genomes and novel life forms. Truly phenomenal results have been obtained by pioneering groups--for instance, the combinatorial synthesis of genetic networks, genome synthesis using BioBricks, and hybridization chain reaction (HCR), in which stable DNA monomers assemble only upon exposure to a target DNA fragment, biomolecular self-assembly pathways, etc. Such work strongly suggests that nanotechnology and synthetic biology together seem poised to constitute the most transformative development of the 21st century. In this paper, we present a Constraint Programming (CP) approach to solve the RNA inverse folding problem. Given a target RNA secondary structure, we determine an RNA sequence which folds into the target structure; i.e. whose minimum free energy structure is the target structure. Our approach represents a step forward in RNA design--we produce the first complete RNA inverse folding approach which allows for the specification of a wide range of design constraints. We also introduce a Large Neighborhood Search approach which allows us to tackle larger instances at the cost of losing completeness, while retaining the advantages of meeting design constraints (motif, GC-content, etc.). Results demonstrate that our software, RNAiFold, performs as well or better than all state-of-the-art approaches; nevertheless, our approach is unique in terms of completeness, flexibility, and the support of various design constraints. The algorithms presented in this paper are publicly available via the interactive webserver http://bioinformatics.bc.edu/clotelab/RNAiFold; additionally, the source code can be downloaded from that site. PMID:23600819
NASA Astrophysics Data System (ADS)
Liu, Jinfei; Chen, Ming; Wang, Lei; Wu, Qidi
2014-05-01
The rapid expansion of enterprises makes product collaborative design (PCD) a critical issue under the distributed heterogeneous environment, but as the collaborative task of large-scale network becomes more complicated, neither unified task decomposition and allocation methodology nor Agent-based network management platform can satisfy the increasing demands. In this paper, to meet requirements of PCD for distributed product development, a collaborative design mechanism based on the thought of modularity and the Agent technology is presented. First, the top-down 4-tier process model based on task-oriented modular and Agent is constructed for PCD after analyzing the mapping relationships between requirements and functions in the collaborative design. Second, on basis of sub-task decomposition for PCD based on a mixed method, the mathematic model of task-oriented modular based on multi-objective optimization is established to maximize the module cohesion degree and minimize the module coupling degree, while considering the module executable degree as a restriction. The mathematic model is optimized and simulated by the modified PSO, and the decomposed modules are obtained. Finally, the Agent structure model for collaborative design is put forward, and the optimism matching Agents are selected by using similarity algorithm to implement different task-modules by the integrated reasoning and decision-making mechanism with the behavioral model of collaborative design Agents. With the results of experimental studies for automobile collaborative design, the feasibility and efficiency of this methodology of task-oriented modular and Agent-based collaborative design in the distributed heterogeneous environment are verified. On this basis, an integrative automobile collaborative R&D platform is developed. This research provides an effective platform for automobile manufacturing enterprises to achieve PCD, and helps to promote product numeralization collaborative R&D and
The PMAS Telescope Module: Opto-mechanical Design and Manufacture
NASA Astrophysics Data System (ADS)
Roth, Martin M.; Laux, Uwe; Kelz, Andreas; Dionies, Frank
2003-02-01
PMAS, the Potsdam Multi-Aperture Spectrophotometer, has a modular layout which was intended to provide for flexible operation as a travelling instrument and to accomodate different telescopes. The Telescope Module is the part of the instrument which serves the purpose of mechanical and optical interfacing to the telescope. It contains optical systems to re-image the telescope focal plane onto the lens array, to illuminate the lens array from an internal calibration light source, and to observe an area around the 3D spectroscopy field-of-view with a cryogenic CCD system for acquisition, guiding, and for the simultaneous determination of point-spread-function templates for 3D deconvolution. We discuss the opto-mechanical design and manufacture of these subsystems.
Panel discussion on rock mechanics issues in repository design
Bieniawski, Z.T.; Kim, K.S.; Nataraja, M.
1996-04-01
The panel discussion was introduced by Mr. Z.T.(Richard) Bieniawski and then continued with five additional speakers. The topics covered in the discussion included rock mechanics pertaining to the design of underground facilities for the disposal of radioactive wastes and the safety of such facilities. The speakers included: Mr. Kun-Soo Kim who is a specialist in the area of rock mechanics testing during the Basalt Waste Isolation Project; Dr. Mysore Nataraja who is the senior project manager with the NRC; Dr. Michael Voegele who is the project manager for Science Applications International Corporation (SAIC) on the Yucca Mountain Project; Dr. Edward Cording who is a member of the Nuclear Waste Technical Review Board; and Dr. Hemendra Kalia who is employed by Los Alamos National Laboratory and coordinates various activities of testing programs at the Yucca Mountain Site.
SPICA/SAFARI Fourier transform spectrometer mechanism evolutionary design
NASA Astrophysics Data System (ADS)
van den Dool, Teun C.; Kruizinga, Bob; Braam, Ben C.; Hamelinck, Roger F. M. M.; Loix, Nicolas; Van Loon, Dennis; Dams, Johan
2012-09-01
TNO, together with its partners, have designed a cryogenic scanning mechanism for use in the SAFARI1 Fourier Transform Spectrometer (FTS) on board of the SPICA mission. SPICA is one of the M-class missions competing to be launched in ESA's Cosmic Vision Programme2 in 2022. JAXA3 leads the development of the SPICA satellite and SRON is the prime investigator of the Safari instrument. The FTS scanning mechanism (FTSM) has to meet a 35 mm stroke requirement with an Optical Path Difference resolution of less then 15 nm and must fit in a small volume. It consists of two back-to-back roof-top mirrors mounted on a small carriage, which is moved using a magnetic bearing linear guiding system in combination with a magnetic linear motor serving as the OPD actuator. The FTSM will be used at cryogenic temperatures of 4 Kelvin inducing challenging requirements on the thermal power dissipation and heat leak. The magnetic bearing enables movements over a scanning stroke of 35.5 mm in a small volume. It supports the optics in a free-floating way with no friction, or other non-linearities, with sub-nanometer accuracy. This solution is based on the design of the breadboard ODL (Optical Delay Line) developed for the ESA Darwin mission4 and the MABE mechanism developed by Micromega Dynamics. During the last couple of years the initial design of the SAFARI instrument, as described in an earlier SPIE 2010 paper5, was adapted by the SAFARI team in an evolutionary way to meet the changing requirements of the SPICA payload module. This presentation will focus on the evolution of the FTSM to meet these changing requirements. This work is supported by the Netherlands Space Office (NSO).
NASA Astrophysics Data System (ADS)
Li, Wei; Haese-Coat, Veronique; Ronsin, Joseph
1996-03-01
An adaptive GA scheme is adopted for the optimal morphological filter design problem. The adaptive crossover and mutation rate which make the GA avoid premature and at the same time assure convergence of the program are successfully used in optimal morphological filter design procedure. In the string coding step, each string (chromosome) is composed of a structuring element coding chain concatenated with a filter sequence coding chain. In decoding step, each string is divided into 3 chains which then are decoded respectively into one structuring element with a size inferior to 5 by 5 and two concatenating morphological filter operators. The fitness function in GA is based on the mean-square-error (MSE) criterion. In string selection step, a stochastic tournament procedure is used to replace the simple roulette wheel program in order to accelerate the convergence. The final convergence of our algorithm is reached by a two step converging strategy. In presented applications of noise removal from texture images, it is found that with the optimized morphological filter sequences, the obtained MSE values are smaller than those using corresponding non-adaptive morphological filters, and the optimized shapes and orientations of structuring elements take approximately the same shapes and orientations as those of the image textons.
Optimization of thin noise barrier designs using Evolutionary Algorithms and a Dual BEM Formulation
NASA Astrophysics Data System (ADS)
Toledo, R.; Aznárez, J. J.; Maeso, O.; Greiner, D.
2015-01-01
This work aims at assessing the acoustic efficiency of different thin noise barrier models. These designs frequently feature complex profiles and their implementation in shape optimization processes may not always be easy in terms of determining their topological feasibility. A methodology to conduct both overall shape and top edge optimizations of thin cross section acoustic barriers by idealizing them as profiles with null boundary thickness is proposed. This procedure is based on the maximization of the insertion loss of candidate profiles proposed by an evolutionary algorithm. The special nature of these sorts of barriers makes necessary the implementation of a complementary formulation to the classical Boundary Element Method (BEM). Numerical simulations of the barriers' performance are conducted by using a 2D Dual BEM code in eight different barrier configurations (covering overall shaped and top edge configurations; spline curved and polynomial shaped based designs; rigid and noise absorbing boundaries materials). While results are achieved by using a specific receivers' scheme, the influence of the receivers' location on the acoustic performance is previously addressed. With the purpose of testing the methodology here presented, a numerical model validation on the basis of experimental results from a scale model test [34] is conducted. Results obtained show the usefulness of representing complex thin barrier configurations as null boundary thickness-like models.
The GLAS Science Algorithm Software (GSAS) Detailed Design Document Version 6. Volume 16
NASA Technical Reports Server (NTRS)
Lee, Jeffrey E.
2013-01-01
The Geoscience Laser Altimeter System (GLAS) is the primary instrument for the ICESat (Ice, Cloud and Land Elevation Satellite) laser altimetry mission. ICESat was the benchmark Earth Observing System (EOS) mission for measuring ice sheet mass balance, cloud and aerosol heights, as well as land topography and vegetation characteristics. From 2003 to 2009, the ICESat mission provided multi-year elevation data needed to determine ice sheet mass balance as well as cloud property information, especially for stratospheric clouds common over polar areas. It also provided topography and vegetation data around the globe, in addition to the polar-specific coverage over the Greenland and Antarctic ice sheets.This document describes the detailed design of GLAS Science Algorithm Software (GSAS). The GSAS is used to create the ICESat GLAS standard data products. The National Snow and Ice Data Center (NSDIC) distribute these products. The document contains descriptions, flow charts, data flow diagrams, and structure charts for each major component of the GSAS. The purpose of this document is to present the detailed design of the GSAS. It is intended as a reference source to assist the maintenance programmer in making changes that fix or enhance the documented software.
Toward a theory for design of kinematically constrained mechanical assemblies
Whitney, D.E.; Mantripragada, R.; Adams, J.D.; Rhee, S.J.
1999-12-01
This paper summarizes a theory to support the design of assemblies. It describes a top-down process for designing kinematically constrained assemblies that deliver geometric key characteristics (KCs) that achieve top-level customer requirements. The theory applies to assemblies that take the form of mechanisms (e.g., engines) or structures (e.g., aircraft fuselages). The process begins by creating a kinematic constraint structure and a systematic scheme by which parts are located in space relative to each other, followed by declaration of assembly features that join parts in such a way as to create the desired constraint relationships. This process creates a connective data model containing information to support relevant analyses such as variation buildup, constraint analysis, and establishment of constraining-consistent assembly sequences. Adjustable assemblies, assemblies built using fixtures, and selective assemblies can also be described by this theory.
Design and implementation of a mechanically heterogeneous robot group
NASA Astrophysics Data System (ADS)
Sukhatme, Gaurav S.; Montgomery, James F.; Mataric, Maja J.
1999-08-01
This paper describes the design and construction of a cooperative, heterogeneous robot group comprised of one semi-autonomous aerial robot and two autonomous ground robots. The robots are designed to perform automated surveillance and reconnaissance of an urban outdoor area using onboard sensing. The ground vehicles have GPS, sonar for obstacle detection and avoidance, and a simple color- based vision system. Navigation is performed using an optimal mixture of odometry and GPS. The helicopter is equipped with a GPS/INS system, a camera, and a framegrabber. Each robot has an embedded 486 PC/104 processor running the QNX real-time operating system. Individual robot controllers are behavior-based and decentralized. We describe a control strategy and architecture that coordinates the robots with minimal top- down planning. The overall system is controlled at high level by a single human operator using a specially designed control unit. The operator is able to task the group with a mission using a minimal amount of training. The group can re-task itself based on sensor inputs and can also be re- tasked by the operator. We describe a particular reconnaissance mission that the robots have been tested with, and lessons learned during the design and implementation. Our initial results with these experiments are encouraging given the challenging mechanics of the aerial robot. We conclude the paper with a discussion of ongoing and future work.
The mechanical design for the WEAVE prime focus corrector system
NASA Astrophysics Data System (ADS)
Abrams, Don Carlos; Dee, Kevin; Agócs, Tibor; Lhome, Emilie; Peñate, José; Jaskó, Attila; Bányai, Evelin; Burgal, José A.; Dalton, Gavin; Middleton, Kevin; Bonifacio, Piercarlo; Aguerri, J. Alfonso L.; Trager, S. C.; Balcells, Marc
2014-08-01
WEAVE is the next-generation, wide-field, optical spectroscopy facility for the William Herschel Telescope (WHT) in La Palma, Canary Islands, Spain. The WHT will undergo a significant adaptation to accommodate this facility. A two- degree Prime Focus Corrector (PFC), that includes an Atmospheric Dispersion Compensator, is being planned and is currently in its final design phase. To compensate for the effects of temperature-induced image degradation, the entire PFC system will be translated along the telescope optical axis. The optical system comprises six lenses, the largest of which will have a diameter of 1.1m. Now that the optical elements are in production, the designs for the lens cells and the mounting arrangements are being analysed to ensure that the image quality of the complete system is better than 1.0 arcsec (80% encircled energy diameter) over the full field of view. The new PFC system is designed to be routinely interchanged with the existing top-end ring. This will maximise the versatility of the WHT and allow the two top-end systems to be interchanged as dictated by the scientific needs of the astronomers that will use WEAVE and other instruments on the telescope. This manuscript describes the work that has been carried out in developing the designs for the mechanical subsystems and the plans for mounting the lenses to attain an optical performance that is commensurate with the requirements derived from planning the WEAVE surveys.
NASA Astrophysics Data System (ADS)
Fenner, Jonathan W.; Simon, Solomon H.; Eden, Dayton D.
1994-07-01
As new IR focal plane array (IRFPA) technologies become available, improved methods for coping with array errors must be developed. Traditional methods of nonuniformity correction using simple calibration mode are not adequate to compensate for the inherent nonuniformity and 1/f noise in some arrays. In an effort to compensate for nonuniformity in a HgCdTe IRFPA, and to reduce the effects of 1/f noise over a time interval, a new dynamic neural network (NN) based algorithm was implemented. The algorithm compensates for nonuniformities, and corrects for 1/f noise. A gradient descent algorithm is used with nearest neighbor feedback for training, creating a dynamic model of the IRFPA's gains and offsets, then updating and correcting them continuously. Improvements to the NN include implementation on a IBM 486 computer system, and a close examination of simulated scenes to test the algorithms boundaries. Preliminary designs for a real-time hardware prototype have been developed as well. Simulations were implemented to test the algorithm's ability to correct under a variety of conditions. A wide range of background noise, 1/f noise, object intensities, and background intensities were used. Results indicate that this algorithm can correct efficiently down to the background noise. Our conclusions are that NN based adaptive algorithms will supplement the effectiveness of IRFPA's.
NASA Astrophysics Data System (ADS)
Reed, P. M.; Kollat, J. B.
2005-12-01
This study demonstrates the effectiveness of a modified version of Deb's Non-Dominated Sorted Genetic Algorithm II (NSGAII), which the authors have named the Epsilon-Dominance Non-Dominated Sorted Genetic Algorithm II (Epsilon-NSGAII), at solving a four objective long-term groundwater monitoring (LTM) design test case. The Epsilon-NSGAII incorporates prior theoretical competent evolutionary algorithm (EA) design concepts and epsilon-dominance archiving to improve the original NSGAII's efficiency, reliability, and ease-of-use. This algorithm eliminates much of the traditional trial-and-error parameterization associated with evolutionary multi-objective optimization (EMO) through epsilon-dominance archiving, dynamic population sizing, and automatic termination. The effectiveness and reliability of the new algorithm is compared to the original NSGAII as well as two other benchmark multi-objective evolutionary algorithms (MOEAs), the Epsilon-Dominance Multi-Objective Evolutionary Algorithm (Epsilon-MOEA) and the Strength Pareto Evolutionary Algorithm 2 (SPEA2). These MOEAs have been selected because they have been demonstrated to be highly effective at solving numerous multi-objective problems. The results presented in this study indicate superior performance of the Epsilon-NSGAII in terms of the hypervolume indicator, unary Epsilon-indicator, and first-order empirical attainment function metrics. In addition, the runtime metric results indicate that the diversity and convergence dynamics of the Epsilon-NSGAII are competitive to superior relative to the SPEA2, with both algorithms greatly outperforming the NSGAII and Epsilon-MOEA in terms of these metrics. The improvements in performance of the Epsilon-NSGAII over its parent algorithm the NSGAII demonstrate that the application of Epsilon-dominance archiving, dynamic population sizing with archive injection, and automatic termination greatly improve algorithm efficiency and reliability. In addition, the usability of
Zimmerman, K; Levitis, D; Addicott, E; Pringle, A
2016-02-01
We present a novel algorithm for the design of crossing experiments. The algorithm identifies a set of individuals (a 'crossing-set') from a larger pool of potential crossing-sets by maximizing the diversity of traits of interest, for example, maximizing the range of genetic and geographic distances between individuals included in the crossing-set. To calculate diversity, we use the mean nearest neighbor distance of crosses plotted in trait space. We implement our algorithm on a real dataset of Neurospora crassa strains, using the genetic and geographic distances between potential crosses as a two-dimensional trait space. In simulated mating experiments, crossing-sets selected by our algorithm provide better estimates of underlying parameter values than randomly chosen crossing-sets. PMID:26419337
Jou, Jonathan D; Jain, Swati; Georgiev, Ivelin S; Donald, Bruce R
2016-06-01
Sparse energy functions that ignore long range interactions between residue pairs are frequently used by protein design algorithms to reduce computational cost. Current dynamic programming algorithms that fully exploit the optimal substructure produced by these energy functions only compute the GMEC. This disproportionately favors the sequence of a single, static conformation and overlooks better binding sequences with multiple low-energy conformations. Provable, ensemble-based algorithms such as A* avoid this problem, but A* cannot guarantee better performance than exhaustive enumeration. We propose a novel, provable, dynamic programming algorithm called Branch-Width Minimization* (BWM*) to enumerate a gap-free ensemble of conformations in order of increasing energy. Given a branch-decomposition of branch-width w for an n-residue protein design with at most q discrete side-chain conformations per residue, BWM* returns the sparse GMEC in O([Formula: see text]) time and enumerates each additional conformation in merely O([Formula: see text]) time. We define a new measure, Total Effective Search Space (TESS), which can be computed efficiently a priori before BWM* or A* is run. We ran BWM* on 67 protein design problems and found that TESS discriminated between BWM*-efficient and A*-efficient cases with 100% accuracy. As predicted by TESS and validated experimentally, BWM* outperforms A* in 73% of the cases and computes the full ensemble or a close approximation faster than A*, enumerating each additional conformation in milliseconds. Unlike A*, the performance of BWM* can be predicted in polynomial time before running the algorithm, which gives protein designers the power to choose the most efficient algorithm for their particular design problem. PMID:26744898
Statistical mechanics of simple models of protein folding and design.
Pande, V S; Grosberg, A Y; Tanaka, T
1997-01-01
It is now believed that the primary equilibrium aspects of simple models of protein folding are understood theoretically. However, current theories often resort to rather heavy mathematics to overcome some technical difficulties inherent in the problem or start from a phenomenological model. To this end, we take a new approach in this pedagogical review of the statistical mechanics of protein folding. The benefit of our approach is a drastic mathematical simplification of the theory, without resort to any new approximations or phenomenological prescriptions. Indeed, the results we obtain agree precisely with previous calculations. Because of this simplification, we are able to present here a thorough and self contained treatment of the problem. Topics discussed include the statistical mechanics of the random energy model (REM), tests of the validity of REM as a model for heteropolymer freezing, freezing transition of random sequences, phase diagram of designed ("minimally frustrated") sequences, and the degree to which errors in the interactions employed in simulations of either folding and design can still lead to correct folding behavior. Images FIGURE 2 FIGURE 3 FIGURE 4 FIGURE 6 PMID:9414231
Dynamic Financial Constraints: Distinguishing Mechanism Design from Exogenously Incomplete Regimes*
Karaivanov, Alexander; Townsend, Robert M.
2014-01-01
We formulate and solve a range of dynamic models of constrained credit/insurance that allow for moral hazard and limited commitment. We compare them to full insurance and exogenously incomplete financial regimes (autarky, saving only, borrowing and lending in a single asset). We develop computational methods based on mechanism design, linear programming, and maximum likelihood to estimate, compare, and statistically test these alternative dynamic models with financial/information constraints. Our methods can use both cross-sectional and panel data and allow for measurement error and unobserved heterogeneity. We estimate the models using data on Thai households running small businesses from two separate samples. We find that in the rural sample, the exogenously incomplete saving only and borrowing regimes provide the best fit using data on consumption, business assets, investment, and income. Family and other networks help consumption smoothing there, as in a moral hazard constrained regime. In contrast, in urban areas, we find mechanism design financial/information regimes that are decidedly less constrained, with the moral hazard model fitting best combined business and consumption data. We perform numerous robustness checks in both the Thai data and in Monte Carlo simulations and compare our maximum likelihood criterion with results from other metrics and data not used in the estimation. A prototypical counterfactual policy evaluation exercise using the estimation results is also featured. PMID:25246710
Lauer, Timothy M; Wood, Geoffrey P F; Farkas, David; Sathish, Hasige A; Samra, Hardeep S; Trout, Bernhardt L
2016-06-14
A number of potential degradation routes can limit the shelf life of a biotherapeutic. While these are experimentally measurable, the tests to do so require a substantial investment in both time and material, resources rarely available early in the drug development process. To address the potential degradation route of non-enzymatic hydrolysis, we performed a molecular modeling analysis, together with an experimental study, to gain detailed insight into the reaction. On the basis of the mechanism, an algorithm for predicting the likely cleavage sites of a protein has been created. This algorithm measures four key properties during a molecular dynamics simulation, which relate to the key steps of the hydrolysis mechanism, in particular the rate-determining step (which can vary depending on the local environment). The first two properties include the secondary structure and the surface exposure of the amide bond, both of which help detect if the addition of the proton to the amide bond is possible. The second two properties relate to whether the side chain can cyclize and form a furane ring. These two properties are the orientation of the side chain relative to the amide bond and the number of hydrogen bonds between the side chain and the surrounding protein. Overall, the algorithm performs well at identifying reactive versus nonreactive bonds. The algorithm correctly classifies nearly 90% of all amide bonds following an aspartic or glutamic acid residue as reactive or nonreactive. PMID:27194363
Hamzaid, N A; Fornusek, C; Ruys, A; Davis, G M
2007-12-01
The mechanical design of a constant velocity (isokinetic) leg stepping trainer driven by functional electrical stimulation-evoked muscle contractions was the focus of this paper. The system was conceived for training the leg muscles of neurologically-impaired patients. A commercially available slider crank mechanism for elliptical stepping exercise was adapted to a motorized isokinetic driving mechanism. The exercise system permits constant-velocity pedalling at cadences of 1-60 rev x min(-1). The variable-velocity feature allows low pedalling forces for individuals with very weak leg muscles, yet provides resistance to higher pedalling effort in stronger patients. In the future, the system will be integrated with a computer-controlled neuromuscular stimulator and a feedback control unit to monitor training responses of spinal cord-injured, stroke and head injury patients. PMID:18274073
NASA Astrophysics Data System (ADS)
Li, Yutong; Wang, Yuxin; Duffy, Alex H. B.
2014-11-01
Computer-based conceptual design for routine design has made great strides, yet non-routine design has not been given due attention, and it is still poorly automated. Considering that the function-behavior-structure(FBS) model is widely used for modeling the conceptual design process, a computer-based creativity enhanced conceptual design model(CECD) for non-routine design of mechanical systems is presented. In the model, the leaf functions in the FBS model are decomposed into and represented with fine-grain basic operation actions(BOA), and the corresponding BOA set in the function domain is then constructed. Choosing building blocks from the database, and expressing their multiple functions with BOAs, the BOA set in the structure domain is formed. Through rule-based dynamic partition of the BOA set in the function domain, many variants of regenerated functional schemes are generated. For enhancing the capability to introduce new design variables into the conceptual design process, and dig out more innovative physical structure schemes, the indirect function-structure matching strategy based on reconstructing the combined structure schemes is adopted. By adjusting the tightness of the partition rules and the granularity of the divided BOA subsets, and making full use of the main function and secondary functions of each basic structure in the process of reconstructing of the physical structures, new design variables and variants are introduced into the physical structure scheme reconstructing process, and a great number of simpler physical structure schemes to accomplish the overall function organically are figured out. The creativity enhanced conceptual design model presented has a dominant capability in introducing new deign variables in function domain and digging out simpler physical structures to accomplish the overall function, therefore it can be utilized to solve non-routine conceptual design problem.
The Design of Mechanically Compatible Fasteners for Human Mandible Reconstruction
NASA Technical Reports Server (NTRS)
Roberts, Jack C.; Ecker, John A.; Biermann, Paul J.
1993-01-01
Mechanically compatible fasteners for use with thin or weakened bone sections in the human mandible are being developed to help reduce large strain discontinuities across the bone/implant interface. Materials being considered for these fasteners are a polyetherertherketone (PEEK) resin with continuous quartz or carbon fiber for the screw. The screws were designed to have a shear strength equivalent to that of compact/trabecular bone and to be used with a conventional nut, nut plate, or an expandable shank/blind nut made of a ceramic filled polymer. Physical and finite element models of the mandible were developed in order to help select the best material fastener design. The models replicate the softer inner core of trabecular bone and the hard outer shell of compact bone. The inner core of the physical model consisted of an expanding foam and the hard outer shell consisted of ceramic particles in an epoxy matrix. This model has some of the cutting and drilling attributes of bone and may be appropriate as an educational tool for surgeons and medical students. The finite element model was exercised to establish boundary conditions consistent with the stress profiles associated with mandible bite forces and muscle loads. Work is continuing to compare stress/strain profiles of a reconstructed mandible with the results from the finite element model. When optimized, these design and fastening techniques may be applicable, not only to other skeletal structures, but to any composite structure.
VLSI design of inverse-free Berlekamp-Massey algorithm for Reed-Solomon code
NASA Astrophysics Data System (ADS)
Truong, Trieu-Kien; Chang, Y. W.; Jeng, Jyh H.
2001-11-01
The inverse-free Berlekamp-Massey (BM) algorithm is the simplest technique for Reed-Solomon (RS) code to correct errors. In the decoding process, the BM algorithm is used to find the error locator polynomial with syndromes as the input. Later, the inverse-free BM algorithm is generalized to find the error locator polynomial with given erasure locator polynomial. By this means, the modified algorithm can be used for RS code to correct both errors and erasures. The improvement is achieved by replacing the input of the Berlekamp-Massey algorithm with the Forney syndromes instead of the syndromes. With this improved technique, the complexity of time domain RS decoders for correcting both errors and erasures is reduced substantially from previous approaches. In this paper, the register transfer language of this modified BM algorithm is derived and the VLSI architecture is presented.
Zhu, Di; Schubert, Martin F.; Cho, Jaehee; Schubert, E. Fred; Crawford, Mary H.; Koleske, Daniel D.; Shim, Hyunwook; Sone, Cheolsoo
2012-01-01
Light-emitting diodes are becoming the next-generation light source because of their prominent benefits in energy efficiency, versatility, and benign environmental impact. However, because of the unique polarization effects in III–V nitrides and the high complexity of light-emitting diodes, further breakthroughs towards truly optimized devices are required. Here we introduce the concept of artificial evolution into the device optimization process. Reproduction and selection are accomplished by means of an advanced genetic algorithm and device simulator, respectively. We demonstrate that this approach can lead to new device structures that go beyond conventional approaches. The innovative designs originating from the genetic algorithm and the demonstration of the predicted results by implementing structures suggested by the algorithm establish a new avenue for complex semiconductor device design and optimization.
NASA Astrophysics Data System (ADS)
Ushijima, Timothy T.; Yeh, William W.-G.
2015-12-01
We develop an experimental design algorithm to select locations for a network of observation wells that provide the maximum robust information about unknown hydraulic conductivity in a confined, anisotropic aquifer. Since the information that a design provides is dependent on an aquifer's hydraulic conductivity, a robust design is one that provides the maximum information in the worst-case scenario. The design can be formulated as a max-min optimization problem. The problem is generally non-convex, non-differentiable, and contains integer variables. We use a Genetic Algorithm (GA) to perform the combinatorial search. We employ proper orthogonal decomposition (POD) to reduce the dimension of the groundwater model, thereby reducing the computational burden posed by employing a GA. The GA algorithm exhaustively searches for the robust design across a set of hydraulic conductivities and finds an approximate design (called the High Frequency Observation Well Design) through a Monte Carlo-type search. The results from a small-scale 1-D test case validate the proposed methodology. We then apply the methodology to a realistically-scaled 2-D test case.
NASA Astrophysics Data System (ADS)
Li, Jun; Liu, Bo; Zhao, Yan; Yang, Xiaodong; Lu, Xiaofeng; Wang, Lei
2015-04-01
This paper focuses on creating a new design method optimizing both aspirated compressor airfoil and the aspiration scheme simultaneously. The optimization design method is based on the artificial bee colony algorithm and the CST method, while the flow field is computed by one 2D computational program. The optimization process of the rotor tip and stator tip airfoil from an aspirated fan stage is demonstrated to verify the effectiveness of the new coupling method. The results show that the total pressure losses of the optimized stator tip and rotor tip airfoil are reduced relatively by 54% and 20%, respectively. Artificial bee colony algorithm and CST method indicate a satisfying applicability in aspirated airfoil optimization design. Finally, the features of aspirated airfoil designing process are concluded.
Design of an iterative auto-tuning algorithm for a fuzzy PID controller
NASA Astrophysics Data System (ADS)
Saeed, Bakhtiar I.; Mehrdadi, B.
2012-05-01
Since the first application of fuzzy logic in the field of control engineering, it has been extensively employed in controlling a wide range of applications. The human knowledge on controlling complex and non-linear processes can be incorporated into a controller in the form of linguistic terms. However, with the lack of analytical design study it is becoming more difficult to auto-tune controller parameters. Fuzzy logic controller has several parameters that can be adjusted, such as: membership functions, rule-base and scaling gains. Furthermore, it is not always easy to find the relation between the type of membership functions or rule-base and the controller performance. This study proposes a new systematic auto-tuning algorithm to fine tune fuzzy logic controller gains. A fuzzy PID controller is proposed and applied to several second order systems. The relationship between the closed-loop response and the controller parameters is analysed to devise an auto-tuning method. The results show that the proposed method is highly effective and produces zero overshoot with enhanced transient response. In addition, the robustness of the controller is investigated in the case of parameter changes and the results show a satisfactory performance.
Design of electrocardiography measurement system with an algorithm to remove noise
NASA Astrophysics Data System (ADS)
Kwon, Hyeokjun; Oh, Sechang; Kumar, Prashanth; Varadan, Vijay K.
2011-04-01
Electrocardiography (ECG) is an important diagnostic tool that can provide vital information about diseases that may not be detectable with other biological signals like, SpO2(Oxygen Saturation), pulse rate, respiration, and blood pressure. For this reason, EKG measurement is mandatory for accurate diagnosis. Recent development in information technology has facilitated remote monitoring systems which can check patient's current status. Moreover, remote monitoring systems can obviate the need for patients to go to hospitals periodically. Such representative wireless communication system is Zigbee sensor network because Zigbee sensor network provides low power consumption and multi-device connection. When we measure EKG signal, another important factor that we should consider is about unexpected signals mixed to EKG signal. The unexpected signals give a severe impact in distorting original EKG signal. There are three kinds of types in noise elements such as muscle noise, movement noise, and respiration noise. This paper describes the design method for EKG measurement system with Zigbee sensor network and proposes an algorithm to remove noises from measured ECG signal.
Towards the optimal design of an uncemented acetabular component using genetic algorithms
NASA Astrophysics Data System (ADS)
Ghosh, Rajesh; Pratihar, Dilip Kumar; Gupta, Sanjay
2015-12-01
Aseptic loosening of the acetabular component (hemispherical socket of the pelvic bone) has been mainly attributed to bone resorption and excessive generation of wear particle debris. The aim of this study was to determine optimal design parameters for the acetabular component that would minimize bone resorption and volumetric wear. Three-dimensional finite element models of intact and implanted pelvises were developed using data from computed tomography scans. A multi-objective optimization problem was formulated and solved using a genetic algorithm. A combination of suitable implant material and corresponding set of optimal thicknesses of the component was obtained from the Pareto-optimal front of solutions. The ultra-high-molecular-weight polyethylene (UHMWPE) component generated considerably greater volumetric wear but lower bone density loss compared to carbon-fibre reinforced polyetheretherketone (CFR-PEEK) and ceramic. CFR-PEEK was located in the range between ceramic and UHMWPE. Although ceramic appeared to be a viable alternative to cobalt-chromium-molybdenum alloy, CFR-PEEK seems to be the most promising alternative material.
Combined Simulated Annealing and Genetic Algorithm Approach to Bus Network Design
NASA Astrophysics Data System (ADS)
Liu, Li; Olszewski, Piotr; Goh, Pong-Chai
A new method - combined simulated annealing (SA) and genetic algorithm (GA) approach is proposed to solve the problem of bus route design and frequency setting for a given road network with fixed bus stop locations and fixed travel demand. The method involves two steps: a set of candidate routes is generated first and then the best subset of these routes is selected by the combined SA and GA procedure. SA is the main process to search for a better solution to minimize the total system cost, comprising user and operator costs. GA is used as a sub-process to generate new solutions. Bus demand assignment on two alternative paths is performed at the solution evaluation stage. The method was implemented on four theoretical grid networks of different size and a benchmark network. Several GA operators (crossover and mutation) were utilized and tested for their effectiveness. The results show that the proposed method can efficiently converge to the optimal solution on a small network but computation time increases significantly with network size. The method can also be used for other transport operation management problems.
Jensen, Peter Bjerre; Lysgaard, Steen; Quaade, Ulrich J; Vegge, Tejs
2014-09-28
Metal halide ammines have great potential as a future, high-density energy carrier in vehicles. So far known materials, e.g. Mg(NH3)6Cl2 and Sr(NH3)8Cl2, are not suitable for automotive, fuel cell applications, because the release of ammonia is a multi-step reaction, requiring too much heat to be supplied, making the total efficiency lower. Here, we apply density functional theory (DFT) calculations to predict new mixed metal halide ammines with improved storage capacities and the ability to release the stored ammonia in one step, at temperatures suitable for system integration with polymer electrolyte membrane fuel cells (PEMFC). We use genetic algorithms (GAs) to search for materials containing up to three different metals (alkaline-earth, 3d and 4d) and two different halides (Cl, Br and I) - almost 27,000 combinations, and have identified novel mixtures, with significantly improved storage capacities. The size of the search space and the chosen fitness function make it possible to verify that the found candidates are the best possible candidates in the search space, proving that the GA implementation is ideal for this kind of computational materials design, requiring calculations on less than two percent of the candidates to identify the global optimum. PMID:25115581
NASA Astrophysics Data System (ADS)
Smith, R.; Kasprzyk, J. R.; Zagona, E. A.
2013-12-01
Population growth and climate change, combined with difficulties in building new infrastructure, motivate portfolio-based solutions to ensuring sufficient water supply. Powerful simulation models with graphical user interfaces (GUI) are often used to evaluate infrastructure portfolios; these GUI based models require manual modification of the system parameters, such as reservoir operation rules, water transfer schemes, or system capacities. Multiobjective evolutionary algorithm (MOEA) based optimization can be employed to balance multiple objectives and automatically suggest designs for infrastructure systems, but MOEA based decision support typically uses a fixed problem formulation (i.e., a single set of objectives, decisions, and constraints). This presentation suggests a dynamic framework for linking GUI-based infrastructure models with MOEA search. The framework begins with an initial formulation which is solved using a MOEA. Then, stakeholders can interact with candidate solutions, viewing their properties in the GUI model. This is followed by changes in the formulation which represent users' evolving understanding of exigent system properties. Our case study is built using RiverWare, an object-oriented, data-centered model that facilitates the representation of a diverse array of water resources systems. Results suggest that assumptions within the initial MOEA search are violated after investigating tradeoffs and reveal how formulations should be modified to better capture stakeholders' preferences.
Optimal structural design via optimality criteria as a nonsmooth mechanics problem
NASA Astrophysics Data System (ADS)
Tzaferopoulos, M. Ap.; Stravroulakis, G. E.
1995-06-01
In the theory of plastic structural design via optimality criteria (due to W. Prager), the optimal design problem is transformed to a nonlinear elastic structural analysis problem with appropriate stress-strain laws, which generally include complete vertical branches. In this context, the concept of structural universe (in the sense of G. Rozvany) permits the treatment of complicated optimal layout problems. Recent progress in the field of nonsmooth mechanics makes the solution of structural analysis problems with this kind of 'complete' law possible. Elements from the two fields are combined in this paper for the solution of optimal design and layout problems for structures. The optimal layout of plane trusses with various specific cost functions is studied here as a representative problem. The use of convex, continuous and piecewise linear specific cost functions for the structural members leads to problems of linear variational inequalities or equivalently piecewise linear, convex but nonsmooth optimization problems, which are solved by means of an iterative algorithm based on sequential linear programming techniques. Numerical examples illustrate the theory and its applicability to practical engineering structures. Following a parametric investigation of an optimal bridge design, certain aspects of the optimal truss layout problem are discussed, which can be extended to other types of structural systems as well.
First-principles modeling of catalysts: novel algorithms and reaction mechanisms
NASA Astrophysics Data System (ADS)
Richard, Bryan Goldsmith
A molecular level understanding of a reaction mechanism and the computation of rates requires knowledge of the stable structures and the corresponding transition states that connect them. Temperature, pressure, and environment effects must be included to bridge the 'materials gap' so one can reasonably compare ab initio (first-principles, i.e., having no empirical parameters) predictions with experimental measurements. In this thesis, a few critical problems pertaining to ab initio modeling of catalytic systems are addressed; namely, 1) the issue of building representative models of isolated metal atoms grafted on amorphous supports, 2) modeling inorganic catalytic reactions in non-ideal solutions where the solvent participates in the reaction mechanism, and 3) bridging the materials gap using ab initio thermodynamics to predict the stability of supported nanoparticles under experimental reaction conditions. In Chapter I, a background on first-principles modeling of heterogeneous and homogenous catalysts is provided. Subsequently, to address the problem of modeling catalysis by isolated metal atoms on amorphous supports, we present in Chapter II a sequential-quadratic programming algorithm that systematically predicts the structure and reactivity of isolated active sites on insulating amorphous supports. Modeling solution phase reactions is also a considerable challenge for first-principles modeling, yet when done correctly it can yield critical kinetic and mechanistic insight that can guide experimental investigations. In Chapter III, we examine the formation of peroxorhenium complexes by activation of H2O2, which is key in selective oxidation reactions catalyzed by CH3ReO3 (methyltrioxorhenium, MTO). New experiments and density functional theory (DFT) calculations were conducted to better understand the activation of H2O2 by MTO and to provide a strong experimental foundation for benchmarking computational studies involving MTO and its derivatives. It was found
NASA Technical Reports Server (NTRS)
Morrell, R. A.; Odoherty, R. J.; Ramsey, H. R.; Reynolds, C. C.; Willoughby, J. K.; Working, R. D.
1975-01-01
Data and analyses related to a variety of algorithms for solving typical large-scale scheduling and resource allocation problems are presented. The capabilities and deficiencies of various alternative problem solving strategies are discussed from the viewpoint of computer system design.
Discrete Mechanics and Optimal Control for Space Trajectory Design
NASA Astrophysics Data System (ADS)
Moore, Ashley
Space trajectory design is often achieved through a combination of dynamical systems theory and optimal control. The union of trajectory design techniques utilizing invariant manifolds of the planar circular restricted three-body problem and the optimal control scheme Discrete Mechanics and Optimal Control (DMOC) facilitates the design of low-energy trajectories in the N-body problem. In particular, DMOC is used to optimize a trajectory from the Earth to the Moon in the 4-body problem, removing the mid-course change in velocity, Delta V, usually necessary for such a trajectory while still exploiting the structure from the invariant manifolds. This thesis also focuses on how to adapt DMOC, a method devised with a constant step size, for the highly nonlinear dynamics involved in trajectory design. Mesh refinement techniques that aim to reduce discretization errors in the solution and energy evolution and their effect on DMOC optimization are explored and compared with trajectories created using time adaptive variational integrators. Furthermore, a time adaptive form of DMOC is developed that allows for a variable step size that is updated throughout the optimization process. Time adapted DMOC is based on a discretization of Hamilton's principle applied to the time adapted Lagrangian of the optimal control problem. Variations of the discrete action of the optimal control Lagrangian lead to discrete Euler-Lagrange equations that can be enforced as constraints for a boundary value problem. This new form of DMOC leads to the accurate and efficient solution of optimal control problems with highly nonlinear dynamics. Time adapted DMOC is tested on several space trajectory problems including the elliptical orbit transfer in the 2-body problem and the reconfiguration of a cubesat.
NASA Astrophysics Data System (ADS)
Pan, Zhong-Liang; Chen, Ling; Zhang, Guang-Zhao
2016-04-01
The hybrid CMOS molecular (CMOL) circuit, which combines complementary metal-oxide-semiconductor (CMOS) components with nanoscale wires and switches, can exhibit significantly improved performance. In CMOL circuits, the nanodevices, which are called cells, should be placed appropriately and are connected by nanowires. The cells should be connected such that they follow the shortest path. This paper presents an efficient method of cell allocation in CMOL circuits with the hybrid CMOS/nanodevice structure; the method is based on a cultural algorithm with chaotic behavior. The optimal model of cell allocation is derived, and the coding of an individual representing a cell allocation is described. Then the cultural algorithm with chaotic behavior is designed to solve the optimal model. The cultural algorithm consists of a population space, a belief space, and a protocol that describes how knowledge is exchanged between the population and belief spaces. In this paper, the evolutionary processes of the population space employ a genetic algorithm in which three populations undergo parallel evolution. The evolutionary processes of the belief space use a chaotic ant colony algorithm. Extensive experiments on cell allocation in benchmark circuits showed that a low area usage can be obtained using the proposed method, and the computation time can be reduced greatly compared to that of a conventional genetic algorithm.
QXP: powerful, rapid computer algorithms for structure-based drug design.
McMartin, C; Bohacek, R S
1997-07-01
New methods for docking, template fitting and building pseudo-receptors are described. Full conformational searches are carried out for flexible cyclic and acyclic molecules. QXP (quick explore) search algorithms are derived from the method of Monte Carlo perturbation with energy minimization in Cartesian space. An additional fast search step is introduced between the initial perturbation and energy minimization. The fast search produces approximate low-energy structures, which are likely to minimize to a low energy. For template fitting, QXP uses a superposition force field which automatically assigns short-range attractive forces to similar atoms in different molecules. The docking algorithms were evaluated using X-ray data for 12 protein-ligand complexes. The ligands had up to 24 rotatable bonds and ranged from highly polar to mostly nonpolar. Docking searches of the randomly disordered ligands gave rms differences between the lowest energy docked structure and the energy-minimized X-ray structure, of less than 0.76 A for 10 of the ligands. For all the ligands, the rms difference between the energy-minimized X-ray structure and the closest docked structure was less than 0.4 A, when parts of one of the molecules which are in the solvent were excluded from the rms calculation. Template fitting was tested using four ACE inhibitors. Three ACE templates have been previously published. A single run using QXP generated a series of templates which contained examples of each of the three. A pseudo-receptor, complementary to an ACE template, was built out of small molecules, such as pyrrole, cyclopentanone and propane. When individually energy minimized in the pseudo-receptor, each of the four ACE inhibitors moved with an rms of less than 0.25 A. After random perturbation, the inhibitors were docked into the pseudo-receptor. Each lowest energy docked structure matched the energy-minimized geometry with an rms of less than 0.08 A. Thus, the pseudo-receptor shows steric and
Rock mechanics investigations, design and construction of the Ridracoli dam
NASA Astrophysics Data System (ADS)
Oberti, G.; Bavestrello, F.; Rossi, P. P.; Flamigni, F.
1986-07-01
The Ridracoli arch-gravity concrete dam is the major work in a multipurpose project whose main scope is the water supply to 37 communities in the Forlì and Ravenna Provinces. The particular geological and structural characteristics of the foundation rock mass, consisting of a rhythmical alternation of sandstone, silstone and marl, required a wide program of in situ and laboratory investigations in order to obtain a detailed physical and mechanical characterization of the foundation. The design criteria based on the use of a physical and mathematical model are illustrated as well as the limit equilibrium analysis of the stability conditions of the abutments. Particular attention has been devoted to the problem of the excavation stability; excavation methods and stabilizing works are illustrated in detail. The scepage problems are also presented with the description of grouting and drainage works.
Target Tracking via Crowdsourcing: A Mechanism Design Approach
NASA Astrophysics Data System (ADS)
Cao, Nianxia; Brahma, Swastik; Varshney, Pramod K.
2015-03-01
In this paper, we propose a crowdsourcing based framework for myopic target tracking by designing an incentive-compatible mechanism based optimal auction in a wireless sensor network (WSN) containing sensors that are selfish and profit-motivated. For typical WSNs which have limited bandwidth, the fusion center (FC) has to distribute the total number of bits that can be transmitted from the sensors to the FC among the sensors. To accomplish the task, the FC conducts an auction by soliciting bids from the selfish sensors, which reflect how much they value their energy cost. Furthermore, the rationality and truthfulness of the sensors are guaranteed in our model. The final problem is formulated as a multiple-choice knapsack problem (MCKP), which is solved by the dynamic programming method in pseudo-polynomial time. Simulation results show the effectiveness of our proposed approach in terms of both the tracking performance and lifetime of the sensor network.
Delta3: design and control of a flexure hinge mechanism
NASA Astrophysics Data System (ADS)
Bacher, Jean-Philippe; Bottinelli, Stefano; Breguet, Jean-Marc; Clavel, Reymond
2001-10-01
In the fields of micro positioning, micromanipulation and micro machining, the required motion precision is continuously increasing. The demand also increases for high dynamic performances (large bandwidth, high closed loop stiffness.). In many cases an inappropriate mechanical structure prevents to achieve these objectives. For example backlash or friction have to be reduced as much as possible. In this paper, we propose backlash-free and friction-free manipulators using flexure hinges and direct drive actuators. A three degrees of freedom (dof) parallel robot (X, Y, Z) that is a transposition in a flexible structure of the Delta robot kinematics is presented. We focus on the design and control of the robot. A simple dynamic model is proposed and compared with measurements. The system is characterized and we propose solutions to improve performances. These solutions are tested on a linear stage.
The fern cavitation catapult: mechanism and design principles.
Llorens, C; Argentina, M; Rojas, N; Westbrook, J; Dumais, J; Noblin, X
2016-01-01
Leptosporangiate ferns have evolved an ingenious cavitation catapult to disperse their spores. The mechanism relies almost entirely on the annulus, a row of 12-25 cells, which successively: (i) stores energy by evaporation of the cells' content, (ii) triggers the catapult by internal cavitation, and (iii) controls the time scales of energy release to ensure efficient spore ejection. The confluence of these three biomechanical functions within the confines of a single structure suggests a level of sophistication that goes beyond most man-made devices where specific structures or parts rarely serve more than one function. Here, we study in detail the three phases of spore ejection in the sporangia of the fern Polypodium aureum. For each of these phases, we have written the governing equations and measured the key parameters. For the opening of the sporangium, we show that the structural design of the annulus is particularly well suited to inducing bending deformations in response to osmotic volume changes. Moreover, the measured parameters for the osmoelastic design lead to a near-optimal speed of spore ejection (approx. 10 m s(-1)). Our analysis of the trigger mechanism by cavitation points to a critical cavitation pressure of approximately -100 ± 14 bar, a value that matches the most negative pressures recorded in the xylem of plants. Finally, using high-speed imaging, we elucidated the physics leading to the sharp separation of time scales (30 versus 5000 µs) in the closing dynamics. Our results highlight the importance of the precise tuning of the parameters without which the function of the leptosporangium as a catapult would be severely compromised. PMID:26763327
ERIC Educational Resources Information Center
Hundhausen, Christopher D.; Brown, Jonathan L.
2008-01-01
Within the context of an introductory CS1 unit on algorithmic problem-solving, we are exploring the pedagogical value of a novel active learning activity--the "studio experience"--that actively engages learners with algorithm visualization technology. In a studio experience, student pairs are tasked with (a) developing a solution to an algorithm…
MEPSA: A flexible peak search algorithm designed for uniformly spaced time series
NASA Astrophysics Data System (ADS)
Guidorzi, C.
2015-04-01
We present a novel algorithm aimed at identifying peaks within a uniformly sampled time series affected by uncorrelated Gaussian noise. The algorithm, called "MEPSA" (multiple excess peak search algorithm), essentially scans the time series at different timescales by comparing a given peak candidate with a variable number of adjacent bins. While this has originally been conceived for the analysis of gamma-ray burst light (GRB) curves, its usage can be readily extended to other astrophysical transient phenomena, whose activity is recorded through different surveys. We tested and validated it through simulated featureless profiles as well as simulated GRB time profiles. We showcase the algorithm's potential by comparing with the popular algorithm by Li and Fenimore, that is frequently adopted in the literature. Thanks to its high flexibility, the mask of excess patterns used by MEPSA can be tailored and optimised to the kind of data to be analysed without modifying the code. The C code is made publicly available.
Mechanical and thermal design of the Cascade reactor
Pitts, J.H.
1983-01-01
We present an improved Cascade fusion reaction chamber that is optimized with respect to chamber radius, wall thickness, and pebble blanket outlet temperature. We show results of a parameter study where we varied chamber radius from 3 to 6 m, wall thickness from 15 to 80 mm, and blanket outlet temperature from 900 to 1400 K. Based on these studies, we achieved an optimized chamber with 50% the volume of the original design and 60% of its blanket. Chamber radius is only 4.4 m and its half length is only 5.9 m, decreased from the original 5-m radius and 8-m half-length. In our optimization method, we calculate both thermal and mechanical stresses resulting from x-ray, fusion-pellet-debris, and neutron-generated momentum, pressure from ablated material, centrifugal action, vacuum inside the chamber, and gravity. We add the mechanical stresses to thermal stresses and keep the total less than the yield stress. Further, we require that fluctuations in these stresses be less than that which would produce creep-fatigue failure within the chamber 30-year lifetime.
NASA Astrophysics Data System (ADS)
Li, Zhi-Hui; Ma, Qiang; Cui, Junzhi
2016-06-01
The new second-order two-scale (SOTS) finite element algorithm is developed for the dynamic thermo-mechanical coupling problems in axisymmetric and spherical symmetric structures made of composite materials. The axisymmetric structure considered is periodic in both radial and axial directions and homogeneous in circumferential direction. The spherical symmetric structure is only periodic in radial direction. The dynamic thermo-mechanical coupling model is presented and the equivalent compact form is derived. Then, the cell problems, effective material coefficients and the homogenized thermo-mechanical coupling problem are obtained successively by the second-order asymptotic expansion of the temperature increment and displacement. The homogenized material obtained is manifested with the anisotropic property in the circumferential direction. The explicit expressions of the homogenized coefficients in the plane axisymmetric and spherical symmetric cases are given and both the derivation of the analytical solutions of the cell functions and the quasi-static thermoelasticity problems are discussed. Based on the SOTS method, the corresponding finite-element procedure is presented and the unconditionally stable implicit algorithm is established. Some numerical examples are solved and the mutual interaction between the temperature and displacement field is studied under the condition of structural vibration. The computational results demonstrate that the second-order asymptotic analysis finite-element algorithm is feasible and effective in simulating and predicting the dynamic thermo-mechanical behaviors of the composite materials with small periodic configurations in axisymmetric and spherical symmetric structures. This may provide a vital computational tool for analyzing composite material internal temperature distribution and structural deformation induced by the dynamic thermo-mechanical coupling response under strong aerothermodynamic environment.
Algorithm for ventricular capture verification based on the mechanical evoked response.
Yaacoby, E; Akselrod, S; Eldar, M; Glikson, M
2005-07-01
Automatic pacemaker capture verification is important for maintaining safety and low energy consumption in pacemaker patients. A new algorithm was developed, based on impedance measurement between pacing electrode poles, which reflects the distribution of the conducting medium between the poles and changes with effective contraction. Data acquired during pacemaker implant in 17 subjects were analysed, with intracardiac impedance recorded while pacing was performed in the ventricle at varying energies, resulting in multiple-captured and non-captured beats. The impedance signals of all captured/non-captured beats were analysed using three different algorithms, based on the morphology of the impedance signal. The algorithm decision for each beat was compared with an actual capture or non-capture, as determined from the simultaneous recording of surface ECG. Two of the three algorithms (Z1 and Zn) were based on impedance values, and one (Z'n) was based on the first derivative of the impedance. Z1 was based on a single sample, whereas Z'n and Z'n were based on several samples in each beat. The total accuracy for each was Z1: 43%, Zn: 87%, Z'n: 92%. It was concluded that impedance-based capture verification is feasible, that a multiple rather than single sample approach for signal classification is both feasible and superior, and that first derivative analysis with multiple samples (Z'n) provides the best results. PMID:16255434
Hamilton, Lei; McConley, Marc; Angermueller, Kai; Goldberg, David; Corba, Massimiliano; Kim, Louis; Moran, James; Parks, Philip D; Sang Chin; Widge, Alik S; Dougherty, Darin D; Eskandar, Emad N
2015-08-01
A fully autonomous intracranial device is built to continually record neural activities in different parts of the brain, process these sampled signals, decode features that correlate to behaviors and neuropsychiatric states, and use these features to deliver brain stimulation in a closed-loop fashion. In this paper, we describe the sampling and stimulation aspects of such a device. We first describe the signal processing algorithms of two unsupervised spike sorting methods. Next, we describe the LFP time-frequency analysis and feature derivation from the two spike sorting methods. Spike sorting includes a novel approach to constructing a dictionary learning algorithm in a Compressed Sensing (CS) framework. We present a joint prediction scheme to determine the class of neural spikes in the dictionary learning framework; and, the second approach is a modified OSort algorithm which is implemented in a distributed system optimized for power efficiency. Furthermore, sorted spikes and time-frequency analysis of LFP signals can be used to generate derived features (including cross-frequency coupling, spike-field coupling). We then show how these derived features can be used in the design and development of novel decode and closed-loop control algorithms that are optimized to apply deep brain stimulation based on a patient's neuropsychiatric state. For the control algorithm, we define the state vector as representative of a patient's impulsivity, avoidance, inhibition, etc. Controller parameters are optimized to apply stimulation based on the state vector's current state as well as its historical values. The overall algorithm and software design for our implantable neural recording and stimulation system uses an innovative, adaptable, and reprogrammable architecture that enables advancement of the state-of-the-art in closed-loop neural control while also meeting the challenges of system power constraints and concurrent development with ongoing scientific research designed
An integrated mechanical design concept for the final focusingregion for the HIF point design
Brown, T.; Sabbi, G.-L.; Barnard, J.J.; Heitzenroeder, P.; Chun,J.; Schmidt, J.; Yu, S.S.; Peterson, P.F.; Abbott, R.P.; Callahan, D.A.; Latkowski, J.F.; Logan, B.G.; Meier, W.R.; Pemberton, S.J.; Rose, D.V.; Sharp, W.M.; Welch, D.R.
2002-11-21
A design study was undertaken to develop a ''first cut'' integrated mechanical design concept of the final focusing region for a conceptual IFE power plant that considers the major issues which must be addressed in an integrated driver and chamber system. The conceptual design in this study requires a total of 120 beamlines located in two conical arrays attached on the sides of the target chamber 180 degrees apart. Each beamline consists of four large-aperture superconducting quadrupole magnets and a dipole magnet. The major interface issues include radiation shielding and thermal insulation of the superconducting magnets; reaction of electromagnetic loads between the quadrupoles; alignment of the magnets; isolation of the vacuum regions in the target chamber from the beamline, and assembly and maintenance.
Designing the Structure of Carbon Fibers for Optimal Mechanical Properties
Ozcan, Soydan; Vautard, Frederic; Naskar, Amit K
2014-01-01
Carbon fiber manufacturing follows generic processing steps: formation of thermoplastic fibers, stabilization, and carbonization. The final structures and end properties of the carbon fiber can differ significantly depending on the precursor chemistry and the associated processing sciences. Polyacrylonitrile (PAN) and mesophase pitch are the predominant precursors used in the production of carbon fibers. PAN-based carbon fibers consist of nanocrystalline graphitic domains typically 1.5 5 nm in size surrounded by amorphous carbon; in contrast, pitch-based carbon fibers are 10 50 nm crystallites with the graphitic (002) planes mostly aligned parallel to the fiber axis. It has been seen that the skin core structure of PAN-based carbon fibers plays a significant role in their mechanical properties. Designing a more homogenous carbon fiber microstructure by controlling the starting polymer and process parameters results in a different set of tensile strengths and elastic moduli. In this study the microstructural defect distribution (0.1 200 nm), measured by small-angle X-ray scattering, was shown to be directly related to the tensile strength of the carbon fibers. Here the formation of carbon structures from various polymer precursors is reviewed. Such a comprehensive understanding offers the opportunity to design carbon fiber microstructures with improved properties and to ultimately create new types of carbon fibers from alternative precursors at reduced cost.
Opto-mechanical design of a beam launch telescope
NASA Astrophysics Data System (ADS)
Moon, Il; Lee, Soosang; Cho, Myung K.
2005-08-01
The design and development of a beam launch telescope (BLT) was addressed herein. The BLT optical instruments have been commonly used for the applications of adaptive optics (laser guide star), optical communications, and other laser powered optical systems. In this study, a BLT with a primary mirror of 700 mm was investigated as a prototype optical system. The BLT optical system includes a lightweight primary mirror of 700 mm in daimeter, a secondary mirror of 110 mm, a fast steering mirror of 200 mm, and three flat mirrors (array/relay mirrors) of 200 mm. As a test bed, the BLT system was optimized for a spot size of 100mm at a far field (departed by 1km from the telescope). In this design and development study, a wide range of the opto-mechanical and structural analyses have been performed including: static (gravity and thermal), frequency, dynamic and response analysis, and optical evaluations for minimum optical deformation. The EDS I-DEAS Finite Element program and the PCFRINGE optical program are mainly used to fulfill this analysis. Image motion is also calculated based on line of sight (LOS) sensitivity equations integrated in finite element models.
Basic MR relaxation mechanisms and contrast agent design.
De León-Rodríguez, Luis M; Martins, André F; Pinho, Marco C; Rofsky, Neil M; Sherry, A Dean
2015-09-01
The diagnostic capabilities of magnetic resonance imaging (MRI) have undergone continuous and substantial evolution by virtue of hardware and software innovations and the development and implementation of exogenous contrast media. Thirty years since the first MRI contrast agent was approved for clinical use, a reliance on MR contrast media persists, largely to improve image quality with higher contrast resolution and to provide additional functional characterization of normal and abnormal tissues. Further development of MR contrast media is an important component in the quest for continued augmentation of diagnostic capabilities. In this review we detail the many important considerations when pursuing the design and use of MR contrast media. We offer a perspective on the importance of chemical stability, particularly kinetic stability, and how this influences one's thinking about the safety of metal-ligand-based contrast agents. We discuss the mechanisms involved in MR relaxation in the context of probe design strategies. A brief description of currently available contrast agents is accompanied by an in-depth discussion that highlights promising MRI contrast agents in the development of future clinical and research applications. Our intention is to give a diverse audience an improved understanding of the factors involved in developing new types of safe and highly efficient MR contrast agents and, at the same time, provide an appreciation of the insights into physiology and disease that newer types of responsive agents can provide. PMID:25975847
Design of mechanically-tunable photonic crystal split-beam nanocavity.
Lin, Tong; Tian, Feng; Shi, Peng; Chau, Fook Siong; Zhou, Guangya; Tang, Xiaosong; Deng, Jie
2015-08-01
Photonic crystal split-beam nanocavities allow for ultra-sensitive optomechanical transductions but are degraded due to their relatively low optical quality factors. We have proposed and experimentally demonstrated a new type of one-dimensional photonic crystal split-beam nanocavity optimized for an ultra-high optical-quality factor. The design is based on the combination of the deterministic method and hill-climbing algorithm. The latter is the simplest and most straightforward method of the local search algorithm that provides the local maximum of the chosen quality factors. This split-beam nanocavity is made up of two mechanical uncoupled cantilever beams with Bragg mirrors patterned onto it and separated by a 75-nm air gap. Experimental results emphasize that the quality factor of the second-order TE mode can be as high as 1.99×10(4). Additionally, one beam of the device is actuated in the lateral direction with the aid of a NEMS actuator, and the quality factor maintains quite well even if there is a lateral offset up to 64 nm. Potentially promising applications, such as sensitive optomechanical torque sensor, local tuning of Fano resonance, all-optical-reconfigurable filters, etc., are foreseen. PMID:26258343
NASA Astrophysics Data System (ADS)
Ono, Chihiro; Mita, Akira
2012-04-01
Due to an increase in an elderly-people household, and global warming, the design of building spaces requires delicate consideration of the needs of elderly-people. Studies of intelligent spaces that can control suitable devices for residents may provide some of functions needed. However, these intelligent spaces are based on predefined scenarios so that it is difficult to handle unexpected circumstances and adapt to the needs of people. This study aims to suggest a Genetic adaption algorithm for building spaces. The feasibility of the algorithm is tested by simulation. The algorithm extend the existing design methodology by reflecting ongoing living information quickly in the variety of patterns.
Minato, A; Sugimoto, N
1998-01-20
A four-element retroreflector was designed for satellite laser ranging and Earth-satellite-Earth laser long-path absorption measurement of the atmosphere. The retroreflector consists of four symmetrically located corner retroreflectors. Each retroreflector element has curved mirrors and tuned dihedral angles to correct velocity aberrations. A genetic algorithm was employed to optimize dihedral angles of each element and the directions of the four elements. The optimized four-element retroreflector has high reflectance with a reasonably broad angular coverage. It is also shown that the genetic algorithm is effective for optimizing optics with many parameters. PMID:18268603
NASA Astrophysics Data System (ADS)
Javad Kazemzadeh-Parsi, Mohammad; Daneshmand, Farhang; Ahmadfard, Mohammad Amin; Adamowski, Jan; Martel, Richard
2015-01-01
In the present study, an optimization approach based on the firefly algorithm (FA) is combined with a finite element simulation method (FEM) to determine the optimum design of pump and treat remediation systems. Three multi-objective functions in which pumping rate and clean-up time are design variables are considered and the proposed FA-FEM model is used to minimize operating costs, total pumping volumes and total pumping rates in three scenarios while meeting water quality requirements. The groundwater lift and contaminant concentration are also minimized through the optimization process. The obtained results show the applicability of the FA in conjunction with the FEM for the optimal design of groundwater remediation systems. The performance of the FA is also compared with the genetic algorithm (GA) and the FA is found to have a better convergence rate than the GA.
NASA Technical Reports Server (NTRS)
Whiffen, Gregory J.
2006-01-01
Mystic software is designed to compute, analyze, and visualize optimal high-fidelity, low-thrust trajectories, The software can be used to analyze inter-planetary, planetocentric, and combination trajectories, Mystic also provides utilities to assist in the operation and navigation of low-thrust spacecraft. Mystic will be used to design and navigate the NASA's Dawn Discovery mission to orbit the two largest asteroids, The underlying optimization algorithm used in the Mystic software is called Static/Dynamic Optimal Control (SDC). SDC is a nonlinear optimal control method designed to optimize both 'static variables' (parameters) and dynamic variables (functions of time) simultaneously. SDC is a general nonlinear optimal control algorithm based on Bellman's principal.
Sivakamasundari, J; Natarajan, V
2015-01-01
Diabetic Retinopathy (DR) is a disorder that affects the structure of retinal blood vessels due to long-standing diabetes mellitus. Automated segmentation of blood vessel is vital for periodic screening and timely diagnosis. An attempt has been made to generate continuous retinal vasculature for the design of Content Based Image Retrieval (CBIR) application. The typical normal and abnormal retinal images are preprocessed to improve the vessel contrast. The blood vessels are segmented using evolutionary based Harmony Search Algorithm (HSA) combined with Otsu Multilevel Thresholding (MLT) method by best objective functions. The segmentation results are validated with corresponding ground truth images using binary similarity measures. The statistical, textural and structural features are obtained from the segmented images of normal and DR affected retina and are analyzed. CBIR in medical image retrieval applications are used to assist physicians in clinical decision-support techniques and research fields. A CBIR system is developed using HSA based Otsu MLT segmentation technique and the features obtained from the segmented images. Similarity matching is carried out between the features of query and database images using Euclidean Distance measure. Similar images are ranked and retrieved. The retrieval performance of CBIR system is evaluated in terms of precision and recall. The CBIR systems developed using HSA based Otsu MLT and conventional Otsu MLT methods are compared. The retrieval performance such as precision and recall are found to be 96% and 58% for CBIR system using HSA based Otsu MLT segmentation. This automated CBIR system could be recommended for use in computer assisted diagnosis for diabetic retinopathy screening. PMID:25996728
Yoshimaru, Eriko S.; Randtke, Edward A.; Pagel, Mark D.; Cárdenas-Rodríguez, Julio
2016-01-01
Pulsed Chemical Exchange Saturation Transfer (CEST) MRI experimental parameters and RF saturation pulse shapes were optimized using a multiobjective genetic algorithm. The optimization was carried out for RF saturation duty cycles of 50% and 90%, and results were compared to continuous wave saturation and Gaussian waveform. In both simulation and phantom experiments, continuous wave saturation performed the best, followed by parameters and shapes optimized by the genetic algorithm and then followed by Gaussian waveform. We have successfully demonstrated that the genetic algorithm is able to optimize pulse CEST parameters and that the results are translatable to clinical scanners. PMID:26778301
NASA Astrophysics Data System (ADS)
Yoshimaru, Eriko S.; Randtke, Edward A.; Pagel, Mark D.; Cárdenas-Rodríguez, Julio
2016-02-01
Pulsed Chemical Exchange Saturation Transfer (CEST) MRI experimental parameters and RF saturation pulse shapes were optimized using a multiobjective genetic algorithm. The optimization was carried out for RF saturation duty cycles of 50% and 90%, and results were compared to continuous wave saturation and Gaussian waveform. In both simulation and phantom experiments, continuous wave saturation performed the best, followed by parameters and shapes optimized by the genetic algorithm and then followed by Gaussian waveform. We have successfully demonstrated that the genetic algorithm is able to optimize pulse CEST parameters and that the results are translatable to clinical scanners.
NASA Astrophysics Data System (ADS)
Fan, Desheng; Meng, Xiangfeng; Wang, Yurong; Yang, Xiulun; Peng, Xiang; He, Wenqi; Dong, Guoyan; Chen, Hongyi
2013-11-01
We propose an asymmetric cryptosystem based on two-step phase-shifting interferometry (PSI) and elliptic curve (EC) public-key cryptographic algorithm, in which one image is encrypted to two interferograms by double random-phase encoding (DRPE) in Fresnel domain and two-step PSI, and the session keys such as geometrical parameters and pseudo-random seeds, are asymmetrically encoded and decoded with the aid of EC algorithm. The receiver, who possesses the corresponding private key generated by EC algorithm, can successfully decipher the transmitted data using the extracted session keys. The utilization of EC asymmetric cryptosystem solves the problem of key management and dispatch, which is inevitable in the conventional optical symmetric cryptosystems. Not only computer simulation, but also software design and development are carried out to verify the feasibility of the proposed cryptosystem.
An, Jianfei; Song, Kezhu; Zhang, Shuangxi; Yang, Junfeng; Cao, Ping
2014-01-01
An improved method based on a genetic algorithm (GA) is developed to design a broadband electrical impedance matching network for piezoelectric ultrasound transducer. A key feature of the new method is that it can optimize both the topology of the matching network and perform optimization on the components. The main idea of this method is to find the optimal matching network in a set of candidate topologies. Some successful experiences of classical algorithms are absorbed to limit the size of the set of candidate topologies and greatly simplify the calculation process. Both binary-coded GA and real-coded GA are used for topology optimization and components optimization, respectively. Some calculation strategies, such as elitist strategy and clearing niche method, are adopted to make sure that the algorithm can converge to the global optimal result. Simulation and experimental results prove that matching networks with better performance might be achieved by this improved method. PMID:24743156
NASA Astrophysics Data System (ADS)
Lu, Lin; Chang, Yunlong; Li, Yingmin; Lu, Ming
2013-05-01
An orthogonal experiment was conducted by the means of multivariate nonlinear regression equation to adjust the influence of external transverse magnetic field and Ar flow rate on welding quality in the process of welding condenser pipe by high-speed argon tungsten-arc welding (TIG for short). The magnetic induction and flow rate of Ar gas were used as optimum variables, and tensile strength of weld was set to objective function on the base of genetic algorithm theory, and then an optimal design was conducted. According to the request of physical production, the optimum variables were restrained. The genetic algorithm in the MATLAB was used for computing. A comparison between optimum results and experiment parameters was made. The results showed that the optimum technologic parameters could be chosen by the means of genetic algorithm with the conditions of excessive optimum variables in the process of high-speed welding. And optimum technologic parameters of welding coincided with experiment results.
NASA Astrophysics Data System (ADS)
Hartmann, Alexander K.; Weigt, Martin
2005-10-01
A concise, comprehensive introduction to the topic of statistical physics of combinatorial optimization, bringing together theoretical concepts and algorithms from computer science with analytical methods from physics. The result bridges the gap between statistical physics and combinatorial optimization, investigating problems taken from theoretical computing, such as the vertex-cover problem, with the concepts and methods of theoretical physics. The authors cover rapid developments and analytical methods that are both extremely complex and spread by word-of-mouth, providing all the necessary basics in required detail. Throughout, the algorithms are shown with examples and calculations, while the proofs are given in a way suitable for graduate students, post-docs, and researchers. Ideal for newcomers to this young, multidisciplinary field.
NASA Astrophysics Data System (ADS)
Liu, Y.
2014-12-01
The Chinese carbon dioxide observation satellite (TanSat) project is the national high technology research and development program. It is funded by the ministry of science and technology of the people's republic of China and the Chinese Academy of Sciences. TanSat will monitor carbon dioxide in Sun-Synchronous orbit by a hyper resolution grating spectrometer - Carbon Dioxide Sensor. A wide field of view moderate resolution imaging spectrometer - Cloud and Aerosol Polarization Imager (CAPI) will measure the aerosol and cloud properties synchronously. TanSat project turned to Critical Design Phase after Preliminary Design Review on June 2013, and it plan to finish Critical Design Review on December 2014 and launch on July 2016. A multi-bands retrieval algorithm has been developed to approach XCO2 with applying O2A band observation to reduce aerosol and cirrus cloud influence. The state vector list has been modified from previous two-bands algorithm by adding aerosol model parameters, cirrus cloud model parameters and linear correction on O2A bands. Application of TanSat XCO2 retrieval Algorithm on GOSAT Observation (ATANGO) has been developed from multi-bands TanSat algorithm. GOSAT observation has been used in retrieval experiment of ATANGO. A preliminary inter comparison test has been carried out with the XCO2 product of University of Leicester (UoL) full physics algorithm. The bias of 1.2 hPa (~0.1%) and 2.4ppm (~0.6%) of surface pressure and XCO2 between ATANGO and UoL were indicated, and the standard deviation of 2.8hPa (~0.28%) and 1.23ppm (~0.3%) of surface pressure and XCO2 between ATANGO and UoL were found. The Ground-based observation network of XCO2 in China was developed, which include three Fourier transform infrared spectroscopy (IFS-125) over Xinglong, Beijing, Shenzhen, and three Optical Spectrum Analyzers (OSA) over Shangdong, Hainan Island, and Dunhuang, with different latitude and background. The measurement spectrum has been investigated with a
Design and Implementation of Hybrid CORDIC Algorithm Based on Phase Rotation Estimation for NCO
Zhang, Chaozhu; Han, Jinan; Li, Ke
2014-01-01
The numerical controlled oscillator has wide application in radar, digital receiver, and software radio system. Firstly, this paper introduces the traditional CORDIC algorithm. Then in order to improve computing speed and save resources, this paper proposes a kind of hybrid CORDIC algorithm based on phase rotation estimation applied in numerical controlled oscillator (NCO). Through estimating the direction of part phase rotation, the algorithm reduces part phase rotation and add-subtract unit, so that it decreases delay. Furthermore, the paper simulates and implements the numerical controlled oscillator by Quartus II software and Modelsim software. Finally, simulation results indicate that the improvement over traditional CORDIC algorithm is achieved in terms of ease of computation, resource utilization, and computing speed/delay while maintaining the precision. It is suitable for high speed and precision digital modulation and demodulation. PMID:25110750