Optimal Experimental Design for Model Discrimination
Myung, Jay I.; Pitt, Mark A.
2009-01-01
Models of a psychological process can be difficult to discriminate experimentally because it is not easy to determine the values of the critical design variables (e.g., presentation schedule, stimulus structure) that will be most informative in differentiating them. Recent developments in sampling-based search methods in statistics make it possible to determine these values, and thereby identify an optimal experimental design. After describing the method, it is demonstrated in two content areas in cognitive psychology in which models are highly competitive: retention (i.e., forgetting) and categorization. The optimal design is compared with the quality of designs used in the literature. The findings demonstrate that design optimization has the potential to increase the informativeness of the experimental method. PMID:19618983
Parameter estimation and optimal experimental design.
Banga, Julio R; Balsa-Canto, Eva
2008-01-01
Mathematical models are central in systems biology and provide new ways to understand the function of biological systems, helping in the generation of novel and testable hypotheses, and supporting a rational framework for possible ways of intervention, like in e.g. genetic engineering, drug development or treatment of diseases. Since the amount and quality of experimental 'omics' data continue to increase rapidly, there is great need for methods for proper model building which can handle this complexity. In the present chapter we review two key steps of the model building process, namely parameter estimation (model calibration) and optimal experimental design. Parameter estimation aims to find the unknown parameters of the model which give the best fit to a set of experimental data. Optimal experimental design aims to devise the dynamic experiments which provide the maximum information content for subsequent non-linear model identification, estimation and/or discrimination. We place emphasis on the need for robust global optimization methods for proper solution of these problems, and we present a motivating example considering a cell signalling model. PMID:18793133
Optimizing Experimental Designs: Finding Hidden Treasure.
Technology Transfer Automated Retrieval System (TEKTRAN)
Classical experimental design theory, the predominant treatment in most textbooks, promotes the use of blocking designs for control of spatial variability in field studies and other situations in which there is significant variation among heterogeneity among experimental units. Many blocking design...
Optimal Experimental Design for Model Discrimination
ERIC Educational Resources Information Center
Myung, Jay I.; Pitt, Mark A.
2009-01-01
Models of a psychological process can be difficult to discriminate experimentally because it is not easy to determine the values of the critical design variables (e.g., presentation schedule, stimulus structure) that will be most informative in differentiating them. Recent developments in sampling-based search methods in statistics make it…
Achieving optimal SERS through enhanced experimental design
Fisk, Heidi; Westley, Chloe; Turner, Nicholas J.
2016-01-01
One of the current limitations surrounding surface‐enhanced Raman scattering (SERS) is the perceived lack of reproducibility. SERS is indeed challenging, and for analyte detection, it is vital that the analyte interacts with the metal surface. However, as this is analyte dependent, there is not a single set of SERS conditions that are universal. This means that experimental optimisation for optimum SERS response is vital. Most researchers optimise one factor at a time, where a single parameter is altered first before going onto optimise the next. This is a very inefficient way of searching the experimental landscape. In this review, we explore the use of more powerful multivariate approaches to SERS experimental optimisation based on design of experiments and evolutionary computational methods. We particularly focus on colloidal‐based SERS rather than thin film preparations as a result of their popularity. © 2015 The Authors. Journal of Raman Spectroscopy published by John Wiley & Sons, Ltd.
Ceramic processing: Experimental design and optimization
NASA Technical Reports Server (NTRS)
Weiser, Martin W.; Lauben, David N.; Madrid, Philip
1992-01-01
The objectives of this paper are to: (1) gain insight into the processing of ceramics and how green processing can affect the properties of ceramics; (2) investigate the technique of slip casting; (3) learn how heat treatment and temperature contribute to density, strength, and effects of under and over firing to ceramic properties; (4) experience some of the problems inherent in testing brittle materials and learn about the statistical nature of the strength of ceramics; (5) investigate orthogonal arrays as tools to examine the effect of many experimental parameters using a minimum number of experiments; (6) recognize appropriate uses for clay based ceramics; and (7) measure several different properties important to ceramic use and optimize them for a given application.
Simultaneous optimal experimental design for in vitro binding parameter estimation.
Ernest, C Steven; Karlsson, Mats O; Hooker, Andrew C
2013-10-01
Simultaneous optimization of in vitro ligand binding studies using an optimal design software package that can incorporate multiple design variables through non-linear mixed effect models and provide a general optimized design regardless of the binding site capacity and relative binding rates for a two binding system. Experimental design optimization was employed with D- and ED-optimality using PopED 2.8 including commonly encountered factors during experimentation (residual error, between experiment variability and non-specific binding) for in vitro ligand binding experiments: association, dissociation, equilibrium and non-specific binding experiments. Moreover, a method for optimizing several design parameters (ligand concentrations, measurement times and total number of samples) was examined. With changes in relative binding site density and relative binding rates, different measurement times and ligand concentrations were needed to provide precise estimation of binding parameters. However, using optimized design variables, significant reductions in number of samples provided as good or better precision of the parameter estimates compared to the original extensive sampling design. Employing ED-optimality led to a general experimental design regardless of the relative binding site density and relative binding rates. Precision of the parameter estimates were as good as the extensive sampling design for most parameters and better for the poorly estimated parameters. Optimized designs for in vitro ligand binding studies provided robust parameter estimation while allowing more efficient and cost effective experimentation by reducing the measurement times and separate ligand concentrations required and in some cases, the total number of samples. PMID:23943088
Optimal experimental design and therapeutic drug monitoring.
Kulcsár, C; Pronzato, L; Walter, E
1994-06-01
A simple example of intravenous theophylline therapy is used to present and compare various drug administration policies based on stochastic control theory. The simplest approach (Heuristic-Certainty-Equivalence (HCE) control) assumes that the model parameters are known. Prior uncertainty on these parameters can be taken into account by using average optimal (AO) control. The available knowledge about the system can be improved by measuring the drug concentration some time after the beginning of the treatment. This corresponds to the notion of feedback and leads to the HCE feedback (HCEF) and AO feedback (AOF) policies. A further step towards optimality consists in choosing the optimal measurement time given that the final purpose is the control of the system and not the estimation of its parameters. Finally, closed-loop optimal (CLO) control optimally chooses both the dosage regimen and measurement time. PMID:7927864
Optimizing experimental design for comparing models of brain function.
Daunizeau, Jean; Preuschoff, Kerstin; Friston, Karl; Stephan, Klaas
2011-11-01
This article presents the first attempt to formalize the optimization of experimental design with the aim of comparing models of brain function based on neuroimaging data. We demonstrate our approach in the context of Dynamic Causal Modelling (DCM), which relates experimental manipulations to observed network dynamics (via hidden neuronal states) and provides an inference framework for selecting among candidate models. Here, we show how to optimize the sensitivity of model selection by choosing among experimental designs according to their respective model selection accuracy. Using Bayesian decision theory, we (i) derive the Laplace-Chernoff risk for model selection, (ii) disclose its relationship with classical design optimality criteria and (iii) assess its sensitivity to basic modelling assumptions. We then evaluate the approach when identifying brain networks using DCM. Monte-Carlo simulations and empirical analyses of fMRI data from a simple bimanual motor task in humans serve to demonstrate the relationship between network identification and the optimal experimental design. For example, we show that deciding whether there is a feedback connection requires shorter epoch durations, relative to asking whether there is experimentally induced change in a connection that is known to be present. Finally, we discuss limitations and potential extensions of this work. PMID:22125485
Decision-oriented Optimal Experimental Design and Data Collection
NASA Astrophysics Data System (ADS)
O'Malley, D.; Vesselinov, V. V.
2015-12-01
Classical optimal experimental design is a branch of statistics that seeks to construct ("design") a data collection effort ("experiment") that minimizes ("optimal") the uncertainty associated with some quantity of interest. In many real world problems, we are interested in these quantities to help us make a decision. Minimizing the uncertainty associated with the quantity can help inform the decision, but a more holistic approach is possible where the experiment is designed to maximize the information that it provides to the decision-making process. The difference is subtle, but it amounts to focusing on the end-goal (the decision) rather than an intermediary (the quantity). We describe one approach to decision-oriented optimal experimental design that utilizes Bayesian-Information-Gap Decision Theory which combines probabilistic and non-probabilistic methods for uncertainty quantification. In this approach, experimental designs that have a high probability of altering the decision are deemed worthwhile. On the other hand, experimental designs that have little chance or no of altering the decision need not be performed.
Optimal active vibration absorber - Design and experimental results
NASA Technical Reports Server (NTRS)
Lee-Glauser, Gina; Juang, Jer-Nan; Sulla, Jeffrey L.
1993-01-01
An optimal active vibration absorber can provide guaranteed closed-loop stability and control for large flexible space structures with collocated sensors/actuators. The active vibration absorber is a second-order dynamic system which is designed to suppress any unwanted structural vibration. This can be designed with minimum knowledge of the controlled system. Two methods for optimizing the active vibration absorber parameters are illustrated: minimum resonant amplitude and frequency matched active controllers. The Controls-Structures Interaction Phase-1 Evolutionary Model at NASA LaRC is used to demonstrate the effectiveness of the active vibration absorber for vibration suppression. Performance is compared numerically and experimentally using acceleration feedback.
Optimal active vibration absorber: Design and experimental results
NASA Technical Reports Server (NTRS)
Lee-Glauser, Gina; Juang, Jer-Nan; Sulla, Jeffrey L.
1992-01-01
An optimal active vibration absorber can provide guaranteed closed-loop stability and control for large flexible space structures with collocated sensors/actuators. The active vibration absorber is a second-order dynamic system which is designed to suppress any unwanted structural vibration. This can be designed with minimum knowledge of the controlled system. Two methods for optimizing the active vibration absorber parameters are illustrated: minimum resonant amplitude and frequency matched active controllers. The Controls-Structures Interaction Phase-1 Evolutionary Model at NASA LaRC is used to demonstrate the effectiveness of the active vibration absorber for vibration suppression. Performance is compared numerically and experimentally using acceleration feedback.
Criteria for the optimal design of experimental tests
NASA Technical Reports Server (NTRS)
Canavos, G. C.
1972-01-01
Some of the basic concepts are unified that were developed for the problem of finding optimal approximating functions which relate a set of controlled variables to a measurable response. The techniques have the potential for reducing the amount of testing required in experimental investigations. Specifically, two low-order polynomial models are considered as approximations to unknown functionships. For each model, optimal means of designing experimental tests are presented which, for a modest number of measurements, yield prediction equations that minimize the error of an estimated response anywhere inside a selected region of experimentation. Moreover, examples are provided for both models to illustrate their use. Finally, an analysis of a second-order prediction equation is given to illustrate ways of determining maximum or minimum responses inside the experimentation region.
Optimizing an experimental design for an electromagnetic experiment
NASA Astrophysics Data System (ADS)
Roux, Estelle; Garcia, Xavier
2013-04-01
Most of geophysical studies focus on data acquisition and analysis, but another aspect which is gaining importance is the discussion on acquisition of suitable datasets. This can be done through the design of an optimal experiment. Optimizing an experimental design implies a compromise between maximizing the information we get about the target and reducing the cost of the experiment, considering a wide range of constraints (logistical, financial, experimental …). We are currently developing a method to design an optimal controlled-source electromagnetic (CSEM) experiment to detect a potential CO2 reservoir and monitor this reservoir during and after CO2 injection. Our statistical algorithm combines the use of linearized inverse theory (to evaluate the quality of one given design via the objective function) and stochastic optimization methods like genetic algorithm (to examine a wide range of possible surveys). The particularity of our method is that it uses a multi-objective genetic algorithm that searches for designs that fit several objective functions simultaneously. One main advantage of this kind of technique to design an experiment is that it does not require the acquisition of any data and can thus be easily conducted before any geophysical survey. Our new experimental design algorithm has been tested with a realistic one-dimensional resistivity model of the Earth in the region of study (northern Spain CO2 sequestration test site). We show that a small number of well distributed observations have the potential to resolve the target. This simple test also points out the importance of a well chosen objective function. Finally, in the context of CO2 sequestration that motivates this study, we might be interested in maximizing the information we get about the reservoir layer. In that case, we show how the combination of two different objective functions considerably improve its resolution.
A Hierarchical Adaptive Approach to Optimal Experimental Design
Kim, Woojae; Pitt, Mark A.; Lu, Zhong-Lin; Steyvers, Mark; Myung, Jay I.
2014-01-01
Experimentation is at the core of research in the behavioral and neural sciences, yet observations can be expensive and time-consuming to acquire (e.g., MRI scans, responses from infant participants). A major interest of researchers is designing experiments that lead to maximal accumulation of information about the phenomenon under study with the fewest possible number of observations. In addressing this challenge, statisticians have developed adaptive design optimization methods. This letter introduces a hierarchical Bayes extension of adaptive design optimization that provides a judicious way to exploit two complementary schemes of inference (with past and future data) to achieve even greater accuracy and efficiency in information gain. We demonstrate the method in a simulation experiment in the field of visual perception. PMID:25149697
Simulation-based optimal Bayesian experimental design for nonlinear systems
Huan, Xun; Marzouk, Youssef M.
2013-01-01
The optimal selection of experimental conditions is essential to maximizing the value of data for inference and prediction, particularly in situations where experiments are time-consuming and expensive to conduct. We propose a general mathematical framework and an algorithmic approach for optimal experimental design with nonlinear simulation-based models; in particular, we focus on finding sets of experiments that provide the most information about targeted sets of parameters. Our framework employs a Bayesian statistical setting, which provides a foundation for inference from noisy, indirect, and incomplete data, and a natural mechanism for incorporating heterogeneous sources of information. An objective function is constructed from information theoretic measures, reflecting expected information gain from proposed combinations of experiments. Polynomial chaos approximations and a two-stage Monte Carlo sampling method are used to evaluate the expected information gain. Stochastic approximation algorithms are then used to make optimization feasible in computationally intensive and high-dimensional settings. These algorithms are demonstrated on model problems and on nonlinear parameter inference problems arising in detailed combustion kinetics.
Computational procedures for optimal experimental design in biological systems.
Balsa-Canto, E; Alonso, A A; Banga, J R
2008-07-01
Mathematical models of complex biological systems, such as metabolic or cell-signalling pathways, usually consist of sets of nonlinear ordinary differential equations which depend on several non-measurable parameters that can be hopefully estimated by fitting the model to experimental data. However, the success of this fitting is largely conditioned by the quantity and quality of data. Optimal experimental design (OED) aims to design the scheme of actuations and measurements which will result in data sets with the maximum amount and/or quality of information for the subsequent model calibration. New methods and computational procedures for OED in the context of biological systems are presented. The OED problem is formulated as a general dynamic optimisation problem where the time-dependent stimuli profiles, the location of sampling times, the duration of the experiments and the initial conditions are regarded as design variables. Its solution is approached using the control vector parameterisation method. Since the resultant nonlinear optimisation problem is in most of the cases non-convex, the use of a robust global nonlinear programming solver is proposed. For the sake of comparing among different experimental schemes, a Monte-Carlo-based identifiability analysis is then suggested. The applicability and advantages of the proposed techniques are illustrated by considering an example related to a cell-signalling pathway. PMID:18681746
Prediction uncertainty and optimal experimental design for learning dynamical systems
NASA Astrophysics Data System (ADS)
Letham, Benjamin; Letham, Portia A.; Rudin, Cynthia; Browne, Edward P.
2016-06-01
Dynamical systems are frequently used to model biological systems. When these models are fit to data, it is necessary to ascertain the uncertainty in the model fit. Here, we present prediction deviation, a metric of uncertainty that determines the extent to which observed data have constrained the model's predictions. This is accomplished by solving an optimization problem that searches for a pair of models that each provides a good fit for the observed data, yet has maximally different predictions. We develop a method for estimating a priori the impact that additional experiments would have on the prediction deviation, allowing the experimenter to design a set of experiments that would most reduce uncertainty. We use prediction deviation to assess uncertainty in a model of interferon-alpha inhibition of viral infection, and to select a sequence of experiments that reduces this uncertainty. Finally, we prove a theoretical result which shows that prediction deviation provides bounds on the trajectories of the underlying true model. These results show that prediction deviation is a meaningful metric of uncertainty that can be used for optimal experimental design.
NASA Astrophysics Data System (ADS)
Reimer, J.; Schuerch, M.; Slawig, T.
2015-03-01
The geosciences are a highly suitable field of application for optimizing model parameters and experimental designs especially because many data are collected. In this paper, the weighted least squares estimator for optimizing model parameters is presented together with its asymptotic properties. A popular approach to optimize experimental designs called local optimal experimental designs is described together with a lesser known approach which takes into account the potential nonlinearity of the model parameters. These two approaches have been combined with two methods to solve their underlying discrete optimization problem. All presented methods were implemented in an open-source MATLAB toolbox called the Optimal Experimental Design Toolbox whose structure and application is described. In numerical experiments, the model parameters and experimental design were optimized using this toolbox. Two existing models for sediment concentration in seawater and sediment accretion on salt marshes of different complexity served as an application example. The advantages and disadvantages of these approaches were compared based on these models. Thanks to optimized experimental designs, the parameters of these models could be determined very accurately with significantly fewer measurements compared to unoptimized experimental designs. The chosen optimization approach played a minor role for the accuracy; therefore, the approach with the least computational effort is recommended.
Optimizing Experimental Designs Relative to Costs and Effect Sizes.
ERIC Educational Resources Information Center
Headrick, Todd C.; Zumbo, Bruno D.
A general model is derived for the purpose of efficiently allocating integral numbers of units in multi-level designs given prespecified power levels. The derivation of the model is based on a constrained optimization problem that maximizes a general form of a ratio of expected mean squares subject to a budget constraint. This model provides more…
Patel, Dipil; Chauhan, Musharraf; Patel, Ravi; Patel, Jayvadan
2012-03-01
The objective of this work was to apply central composite experimental design to investigate main and interaction effect of formulation parameters in optimizing novel fast disintegration tablets formulation using pullulan as diluents. Face centered central composite experimental design was employed to optimize fast disintegration tablet formulation. The variables studied were concentration of diluents (pullulan, X(1)), superdisintigrant (sodium starch glycolate, X(2)), and direct compression aid (spray dried lactose, X(3)). Tablets were characterized for weight variation, thickness, disintegration time (Y(1)) and hardness (Y(2)). Good correlation between the predicted values and experimental data of the optimized formulation methodology in optimizing fast disintegrating tablets using pullulan as a diluent. PMID:23066220
NASA Astrophysics Data System (ADS)
Reimer, J.; Schürch, M.; Slawig, T.
2014-09-01
The weighted least squares estimator for model parameters was presented together with its asymptotic properties. A popular approach to optimize experimental designs called local optimal experimental designs was described together with a lesser known approach which takes into account a potential nonlinearity of the model parameters. These two approaches were combined with two different methods to solve their underlying discrete optimization problem. All presented methods were implemented in an open source MATLAB toolbox called the Optimal Experimental Design Toolbox whose structure and handling was described. In numerical experiments, the model parameters and experimental design were optimized using this toolbox. Two models for sediment concentration in seawater of different complexity served as application example. The advantages and disadvantages of the different approaches were compared, and an evaluation of the approaches was performed.
Optimization of experimental designs by incorporating NIF facility impacts
NASA Astrophysics Data System (ADS)
Eder, D. C.; Whitman, P. K.; Koniges, A. E.; Anderson, R. W.; Wang, P.; Gunney, B. T.; Parham, T. G.; Koerner, J. G.; Dixit, S. N.; Suratwala, T. I.; Blue, B. E.; Hansen, J. F.; Tobin, M. T.; Robey, H. F.; Spaeth, M. L.; MacGowan, B. J.
2006-06-01
For experimental campaigns on the National Ignition Facility (NIF) to be successful, they must obtain useful data without causing unacceptable impact on the facility. Of particular concern is excessive damage to optics and diagnostic components. There are 192 fused silica main debris shields (MDS) exposed to the potentially hostile target chamber environment on each shot. Damage in these optics results either from the interaction of laser light with contamination and pre-existing imperfections on the optic surface or from the impact of shrapnel fragments. Mitigation of this second damage source is possible by identifying shrapnel sources and shielding optics from them. It was recently demonstrated that the addition of 1.1-mm thick borosilicate disposable debris shields (DDS) blocks the majority of debris and shrapnel fragments from reaching the relatively expensive MDS's. However, DDS's cannot stop large, fast moving fragments. We have experimentally demonstrated one shrapnel mitigation technique showing that it is possible to direct fast moving fragments by changing the source orientation, in this case a Ta pinhole array. Another mitigation method is to change the source material to one that produces smaller fragments. Simulations and validating experiments are necessary to determine which fragments can penetrate or break 1-3 mm thick DDS's. Three-dimensional modeling of complex target-diagnostic configurations is necessary to predict the size, velocity, and spatial distribution of shrapnel fragments. The tools we are developing will be used to assure that all NIF experimental campaigns meet the requirements on allowed level of debris and shrapnel generation.
Analytical and experimental performance of optimal controller designs for a supersonic inlet
NASA Technical Reports Server (NTRS)
Zeller, J. R.; Lehtinen, B.; Geyser, L. C.; Batterton, P. G.
1973-01-01
The techniques of modern optimal control theory were applied to the design of a control system for a supersonic inlet. The inlet control problem was approached as a linear stochastic optimal control problem using as the performance index the expected frequency of unstarts. The details of the formulation of the stochastic inlet control problem are presented. The computational procedures required to obtain optimal controller designs are discussed, and the analytically predicted performance of controllers designed for several different inlet conditions is tabulated. The experimental implementation of the optimal control laws is described, and the experimental results obtained in a supersonic wind tunnel are presented. The control laws were implemented with analog and digital computers. Comparisons are made between the experimental and analytically predicted performance results. Comparisons are also made between the results obtained with continuous analog computer controllers and discrete digital computer versions.
Optimal experimental designs for dose-response studies with continuous endpoints.
Holland-Letz, Tim; Kopp-Schneider, Annette
2015-11-01
In most areas of clinical and preclinical research, the required sample size determines the costs and effort for any project, and thus, optimizing sample size is of primary importance. An experimental design of dose-response studies is determined by the number and choice of dose levels as well as the allocation of sample size to each level. The experimental design of toxicological studies tends to be motivated by convention. Statistical optimal design theory, however, allows the setting of experimental conditions (dose levels, measurement times, etc.) in a way which minimizes the number of required measurements and subjects to obtain the desired precision of the results. While the general theory is well established, the mathematical complexity of the problem so far prevents widespread use of these techniques in practical studies. The paper explains the concepts of statistical optimal design theory with a minimum of mathematical terminology and uses these concepts to generate concrete usable D-optimal experimental designs for dose-response studies on the basis of three common dose-response functions in toxicology: log-logistic, log-normal and Weibull functions with four parameters each. The resulting designs usually require control plus only three dose levels and are quite intuitively plausible. The optimal designs are compared to traditional designs such as the typical setup of cytotoxicity studies for 96-well plates. As the optimal design depends on prior estimates of the dose-response function parameters, it is shown what loss of efficiency occurs if the parameters for design determination are misspecified, and how Bayes optimal designs can improve the situation. PMID:25155192
Chang, Liang-Cheng; Chu, Hone-Jay; Lin, Yu-Pin; Chen, Yu-Wen
2010-10-01
This research develops an optimum design model of groundwater network using genetic algorithm (GA) and modified Newton approach, based on the experimental design conception. The goal of experiment design is to minimize parameter uncertainty, represented by the covariance matrix determinant of estimated parameters. The design problem is constrained by a specified cost and solved by GA and a parameter identification model. The latter estimates optimum parameter value and its associated sensitivity matrices. The general problem is simplified into two classes of network design problems: an observation network design problem and a pumping network design problem. Results explore the relationship between the experimental design and the physical processes. The proposed model provides an alternative to solve optimization problems for groundwater experimental design. PMID:19757116
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
Optimal experimental designs for the estimation of thermal properties of composite materials
NASA Technical Reports Server (NTRS)
Scott, Elaine P.; Moncman, Deborah A.
1994-01-01
Reliable estimation of thermal properties is extremely important in the utilization of new advanced materials, such as composite materials. The accuracy of these estimates can be increased if the experiments are designed carefully. The objectives of this study are to design optimal experiments to be used in the prediction of these thermal properties and to then utilize these designs in the development of an estimation procedure to determine the effective thermal properties (thermal conductivity and volumetric heat capacity). The experiments were optimized by choosing experimental parameters that maximize the temperature derivatives with respect to all of the unknown thermal properties. This procedure has the effect of minimizing the confidence intervals of the resulting thermal property estimates. Both one-dimensional and two-dimensional experimental designs were optimized. A heat flux boundary condition is required in both analyses for the simultaneous estimation of the thermal properties. For the one-dimensional experiment, the parameters optimized were the heating time of the applied heat flux, the temperature sensor location, and the experimental time. In addition to these parameters, the optimal location of the heat flux was also determined for the two-dimensional experiments. Utilizing the optimal one-dimensional experiment, the effective thermal conductivity perpendicular to the fibers and the effective volumetric heat capacity were then estimated for an IM7-Bismaleimide composite material. The estimation procedure used is based on the minimization of a least squares function which incorporates both calculated and measured temperatures and allows for the parameters to be estimated simultaneously.
Recent developments in optimal experimental designs for functional magnetic resonance imaging
Kao, Ming-Hung; Temkit, M'hamed; Wong, Weng Kee
2014-01-01
Functional magnetic resonance imaging (fMRI) is one of the leading brain mapping technologies for studying brain activity in response to mental stimuli. For neuroimaging studies utilizing this pioneering technology, there is a great demand of high-quality experimental designs that help to collect informative data to make precise and valid inference about brain functions. This paper provides a survey on recent developments in experimental designs for fMRI studies. We briefly introduce some analytical and computational tools for obtaining good designs based on a specified design selection criterion. Research results about some commonly considered designs such as blocked designs, and m-sequences are also discussed. Moreover, we present a recently proposed new type of fMRI designs that can be constructed using a certain type of Hadamard matrices. Under certain assumptions, these designs can be shown to be statistically optimal. Some future research directions in design of fMRI experiments are also discussed. PMID:25071884
OPTIMIZING THE PRECISION OF TOXICITY THRESHOLD ESTIMATION USING A TWO-STAGE EXPERIMENTAL DESIGN
An important consideration for risk assessment is the existence of a threshold, i.e., the highest toxicant dose where the response is not distinguishable from background. We have developed methodology for finding an experimental design that optimizes the precision of threshold mo...
Kamairudin, Norsuhaili; Gani, Siti Salwa Abd; Masoumi, Hamid Reza Fard; Hashim, Puziah
2014-01-01
The D-optimal mixture experimental design was employed to optimize the melting point of natural lipstick based on pitaya (Hylocereus polyrhizus) seed oil. The influence of the main lipstick components-pitaya seed oil (10%-25% w/w), virgin coconut oil (25%-45% w/w), beeswax (5%-25% w/w), candelilla wax (1%-5% w/w) and carnauba wax (1%-5% w/w)-were investigated with respect to the melting point properties of the lipstick formulation. The D-optimal mixture experimental design was applied to optimize the properties of lipstick by focusing on the melting point with respect to the above influencing components. The D-optimal mixture design analysis showed that the variation in the response (melting point) could be depicted as a quadratic function of the main components of the lipstick. The best combination of each significant factor determined by the D-optimal mixture design was established to be pitaya seed oil (25% w/w), virgin coconut oil (37% w/w), beeswax (17% w/w), candelilla wax (2% w/w) and carnauba wax (2% w/w). With respect to these factors, the 46.0 °C melting point property was observed experimentally, similar to the theoretical prediction of 46.5 °C. Carnauba wax is the most influential factor on this response (melting point) with its function being with respect to heat endurance. The quadratic polynomial model sufficiently fit the experimental data. PMID:25325152
Optimization of Experimental Design for Estimating Groundwater Pumping Using Model Reduction
NASA Astrophysics Data System (ADS)
Ushijima, T.; Cheng, W.; Yeh, W. W.
2012-12-01
An optimal experimental design algorithm is developed to choose locations for a network of observation wells for estimating unknown groundwater pumping rates in a confined aquifer. The design problem can be expressed as an optimization problem which employs a maximal information criterion to choose among competing designs subject to the specified design constraints. Because of the combinatorial search required in this optimization problem, given a realistic, large-scale groundwater model, the dimensionality of the optimal design problem becomes very large and can be difficult if not impossible to solve using mathematical programming techniques such as integer programming or the Simplex with relaxation. Global search techniques, such as Genetic Algorithms (GAs), can be used to solve this type of combinatorial optimization problem; however, because a GA requires an inordinately large number of calls of a groundwater model, this approach may still be infeasible to use to find the optimal design in a realistic groundwater model. Proper Orthogonal Decomposition (POD) is therefore applied to the groundwater model to reduce the model space and thereby reduce the computational burden of solving the optimization problem. Results for a one-dimensional test case show identical results among using GA, integer programming, and an exhaustive search demonstrating that GA is a valid method for use in a global optimum search and has potential for solving large-scale optimal design problems. Additionally, other results show that the algorithm using GA with POD model reduction is several orders of magnitude faster than an algorithm that employs GA without POD model reduction in terms of time required to find the optimal solution. Application of the proposed methodology is being made to a large-scale, real-world groundwater problem.
Kincl, M; Turk, S; Vrecer, F
2005-03-01
The aim of our research was to apply experimental design methodology in the development and optimization of drug release methods. Diclofenac sodium (2-[(2,6-dichlorophenyl)amino]benzeneacetic acid monosodium salt) was selected as a model drug and Naklofen retard prolonged release tablets, containing 100 mg of diclofenac sodium, were chosen as a model prolonged release system. On the basis of previous results, a three-level three-factorial Box-Behnken experimental design was used to characterize and optimize three physicochemical parameters, i.e. rotation speeds of the stirring elements, pH, and ionic strengths of the dissolution medium, affecting the release of diclofenac sodium from the tablets. The chosen dependent variables (responses) were a cumulative percentage of dissolved diclofenac sodium in 2, 6, 12 and 24 h. For estimation of coefficients in the approximating polynomial function, the least square regression method was applied. Afterwards, the information about the model reliability was verified by using the analysis of variance (ANOVA). The estimation of model factors' significance was performed by Student's t-test. For investigation of the shape of the predicted response surfaces and for model optimization, the canonical analysis was applied. Our study proved that experimental design methodology could efficiently be applied for characterization and optimization of analytical parameters affecting drug release and that it is an economical way of obtaining the maximum amount of information in a short period of time and with the fewest number of experiments. PMID:15707730
NASA Technical Reports Server (NTRS)
Maghami, Peiman G.; Gupta, Sandeep; Joshi, Suresh M.; Walz, Joseph E.
1993-01-01
An optimization-based integrated design approach for flexible space structures is experimentally validated using three types of dissipative controllers, including static, dynamic, and LQG dissipative controllers. The nominal phase-0 of the controls structure interaction evolutional model (CEM) structure is redesigned to minimize the average control power required to maintain specified root-mean-square line-of-sight pointing error under persistent disturbances. The redesign structure, phase-1 CEM, was assembled and tested against phase-0 CEM. It is analytically and experimentally demonstrated that integrated controls-structures design is substantially superior to that obtained through the traditional sequential approach. The capability of a software design tool based on an automated design procedure in a unified environment for structural and control designs is demonstrated.
Issues and recent advances in optimal experimental design for site investigation (Invited)
NASA Astrophysics Data System (ADS)
Nowak, W.
2013-12-01
This presentation provides an overview over issues and recent advances in model-based experimental design for site exploration. The addressed issues and advances are (1) how to provide an adequate envelope to prior uncertainty, (2) how to define the information needs in a task-oriented manner, (3) how to measure the expected impact of a data set that it not yet available but only planned to be collected, and (4) how to perform best the optimization of the data collection plan. Among other shortcomings of the state-of-the-art, it is identified that there is a lack of demonstrator studies where exploration schemes based on expert judgment are compared to exploration schemes obtained by optimal experimental design. Such studies will be necessary do address the often voiced concern that experimental design is an academic exercise with little improvement potential over the well- trained gut feeling of field experts. When addressing this concern, a specific focus has to be given to uncertainty in model structure, parameterizations and parameter values, and to related surprises that data often bring about in field studies, but never in synthetic-data based studies. The background of this concern is that, initially, conceptual uncertainty may be so large that surprises are the rule rather than the exception. In such situations, field experts have a large body of experience in handling the surprises, and expert judgment may be good enough compared to meticulous optimization based on a model that is about to be falsified by the incoming data. In order to meet surprises accordingly and adapt to them, there needs to be a sufficient representation of conceptual uncertainty within the models used. Also, it is useless to optimize an entire design under this initial range of uncertainty. Thus, the goal setting of the optimization should include the objective to reduce conceptual uncertainty. A possible way out is to upgrade experimental design theory towards real-time interaction
Krstulovich, S.F.
1987-10-31
This report is developed as part of the Fermilab D-0 Experimental Facility Project Title II Design Documentation Update. As such, it concentrates primarily on HVAC mechanical systems design optimization and cost analysis.
Optimal design and experimental analyses of a new micro-vibration control payload-platform
NASA Astrophysics Data System (ADS)
Sun, Xiaoqing; Yang, Bintang; Zhao, Long; Sun, Xiaofen
2016-07-01
This paper presents a new payload-platform, for precision devices, which possesses the capability of isolating the complex space micro-vibration in low frequency range below 5 Hz. The novel payload-platform equipped with smart material actuators is investigated and designed through optimization strategy based on the minimum energy loss rate, for the aim of achieving high drive efficiency and reducing the effect of the magnetic circuit nonlinearity. Then, the dynamic model of the driving element is established by using the Lagrange method and the performance of the designed payload-platform is further discussed through the combination of the controlled auto regressive moving average (CARMA) model with modified generalized prediction control (MGPC) algorithm. Finally, an experimental prototype is developed and tested. The experimental results demonstrate that the payload-platform has an impressive potential of micro-vibration isolation.
Experimental Investigation of a Point Design Optimized Arrow Wing HSCT Configuration
NASA Technical Reports Server (NTRS)
Narducci, Robert P.; Sundaram, P.; Agrawal, Shreekant; Cheung, S.; Arslan, A. E.; Martin, G. L.
1999-01-01
The M2.4-7A Arrow Wing HSCT configuration was optimized for straight and level cruise at a Mach number of 2.4 and a lift coefficient of 0.10. A quasi-Newton optimization scheme maximized the lift-to-drag ratio (by minimizing drag-to-lift) using Euler solutions from FL067 to estimate the lift and drag forces. A 1.675% wind-tunnel model of the Opt5 HSCT configuration was built to validate the design methodology. Experimental data gathered at the NASA Langley Unitary Plan Wind Tunnel (UPWT) section #2 facility verified CFL3D Euler and Navier-Stokes predictions of the Opt5 performance at the design point. In turn, CFL3D confirmed the improvement in the lift-to-drag ratio obtained during the optimization, thus validating the design procedure. A data base at off-design conditions was obtained during three wind-tunnel tests. The entry into NASA Langley UPWT section #2 obtained data at a free stream Mach number, M(sub infinity), of 2.55 as well as the design Mach number, M(sub infinity)=2.4. Data from a Mach number range of 1.8 to 2.4 was taken at UPWT section #1. Transonic and low supersonic Mach numbers, M(sub infinity)=0.6 to 1.2, was gathered at the NASA Langley 16 ft. Transonic Wind Tunnel (TWT). In addition to good agreement between CFD and experimental data, highlights from the wind-tunnel tests include a trip dot study suggesting a linear relationship between trip dot drag and Mach number, an aeroelastic study that measured the outboard wing deflection and twist, and a flap scheduling study that identifies the possibility of only one leading-edge and trailing-edge flap setting for transonic cruise and another for low supersonic acceleration.
Optimizing an experimental design for a CSEM experiment: methodology and synthetic tests
NASA Astrophysics Data System (ADS)
Roux, E.; Garcia, X.
2014-04-01
Optimizing an experimental design is a compromise between maximizing information we get about the target and limiting the cost of the experiment, providing a wide range of constraints. We present a statistical algorithm for experiment design that combines the use of linearized inverse theory and stochastic optimization technique. Linearized inverse theory is used to quantify the quality of one given experiment design while genetic algorithm (GA) enables us to examine a wide range of possible surveys. The particularity of our algorithm is the use of the multi-objective GA NSGA II that searches designs that fit several objective functions (OFs) simultaneously. This ability of NSGA II is helping us in defining an experiment design that focuses on a specified target area. We present a test of our algorithm using a 1-D electrical subsurface structure. The model we use represents a simple but realistic scenario in the context of CO2 sequestration that motivates this study. Our first synthetic test using a single OF shows that a limited number of well-distributed observations from a chosen design have the potential to resolve the given model. This synthetic test also points out the importance of a well-chosen OF, depending on our target. In order to improve these results, we show how the combination of two OFs using a multi-objective GA enables us to determine an experimental design that maximizes information about the reservoir layer. Finally, we present several tests of our statistical algorithm in more challenging environments by exploring the influence of noise, specific site characteristics or its potential for reservoir monitoring.
Ahmad, A L; Ideris, N; Ooi, B S; Low, S C; Ismail, A
2016-01-01
Statistical experimental design was employed to optimize the preparation conditions of polyvinylidenefluoride (PVDF) membranes. Three variables considered were polymer concentration, dissolving temperature, and casting thickness, whereby the response variable was membrane-protein binding. The optimum preparation for the PVDF membrane was a polymer concentration of 16.55 wt%, a dissolving temperature of 27.5°C, and a casting thickness of 450 µm. The statistical model exhibits a deviation between the predicted and actual responses of less than 5%. Further characterization of the formed PVDF membrane showed that the morphology of the membrane was in line with the membrane-protein binding performance. PMID:27088961
Formulation and optimization by experimental design of eco-friendly emulsions based on d-limonene.
Pérez-Mosqueda, Luis M; Trujillo-Cayado, Luis A; Carrillo, Francisco; Ramírez, Pablo; Muñoz, José
2015-04-01
d-Limonene is a natural occurring solvent that can replace more pollutant chemicals in agrochemical formulations. In the present work, a comprehensive study of the influence of dispersed phase mass fraction, ϕ, and of the surfactant/oil ratio, R, on the emulsion stability and droplet size distribution of d-limonene-in-water emulsions stabilized by a non-ionic triblock copolymer surfactant has been carried out. An experimental full factorial design 3(2) was conducted in order to optimize the emulsion formulation. The independent variables, ϕ and R were studied in the range 10-50 wt% and 0.02-0.1, respectively. The emulsions studied were mainly destabilized by both creaming and Ostwald ripening. Therefore, initial droplet size and an overall destabilization parameter, the so-called turbiscan stability index, were used as dependent variables. The optimal formulation, comprising minimum droplet size and maximum stability was achieved at ϕ=50 wt%; R=0.062. Furthermore, the surface response methodology allowed us to obtain the formulation yielding sub-micron emulsions by using a single step rotor/stator homogenizer process instead of most commonly used two-step emulsification methods. In addition, the optimal formulation was further improved against Ostwald ripening by adding silicone oil to the dispersed phase. The combination of these experimental findings allowed us to gain a deeper insight into the stability of these emulsions, which can be applied to the rational development of new formulations with potential application in agrochemical formulations. PMID:25734966
Abou-Taleb, Noura Hemdan; El-Wasseef, Dalia Rashad; El-Sherbiny, Dina Tawfik; El-Ashry, Saadia Mohamed
2016-05-01
The aim of this work is to optimize a spectrofluorimetric method for the determination of cefdinir (CFN) using the Taguchi method. The proposed method is based on the oxidative coupling reaction of CFN and cerium(IV) sulfate. The quenching effect of CFN on the fluorescence of the produced cerous ions is measured at an emission wavelength (λem ) of 358 nm after excitation (λex ) at 301 nm. The Taguchi orthogonal array L9 (3(4) ) was designed to determine the optimum reaction conditions. The results were analyzed using the signal-to-noise (S/N) ratio and analysis of variance (ANOVA). The optimal experimental conditions obtained from this study were 1 mL of 0.2% MBTH, 0.4 mL of 0.25% Ce(IV), a reaction time of 10 min and methanol as the diluting solvent. The calibration plot displayed a good linear relationship over a range of 0.5-10.0 µg/mL. The proposed method was successfully applied to the determination of CFN in bulk powder and pharmaceutical dosage forms. The results are in good agreement with those obtained using the comparison method. Finally, the Taguchi method provided a systematic and efficient methodology for this optimization, with considerably less effort than would be required for other optimizations techniques. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26456088
Optimization and evaluation of clarithromycin floating tablets using experimental mixture design.
Uğurlu, Timucin; Karaçiçek, Uğur; Rayaman, Erkan
2014-01-01
The purpose of the study was to prepare and evaluate clarithromycin (CLA) floating tablets using experimental mixture design for treatment of Helicobacter pylori provided by prolonged gastric residence time and controlled plasma level. Ten different formulations were generated based on different molecular weight of hypromellose (HPMC K100, K4M, K15M) by using simplex lattice design (a sub-class of mixture design) with Minitab 16 software. Sodium bicarbonate and anhydrous citric acid were used as gas generating agents. Tablets were prepared by wet granulation technique. All of the process variables were fixed. Results of cumulative drug release at 8th h (CDR 8th) were statistically analyzed to get optimized formulation (OF). Optimized formulation, which gave floating lag time lower than 15 s and total floating time more than 10 h, was analyzed and compared with target for CDR 8th (80%). A good agreement was shown between predicted and actual values of CDR 8th with a variation lower than 1%. The activity of clarithromycin contained optimizedformula against H. pylori were quantified using well diffusion agar assay. Diameters of inhibition zones vs. log10 clarithromycin concentrations were plotted in order to obtain a standard curve and clarithromycin activity. PMID:25272652
Doehlert experimental design applied to optimization of light emitting textile structures
NASA Astrophysics Data System (ADS)
Oguz, Yesim; Cochrane, Cedric; Koncar, Vladan; Mordon, Serge R.
2016-07-01
A light emitting fabric (LEF) has been developed for photodynamic therapy (PDT) for the treatment of dermatologic diseases such as Actinic Keratosis (AK). A successful PDT requires homogenous and reproducible light with controlled power and wavelength on the treated skin area. Due to the shape of the human body, traditional PDT with external light sources is unable to deliver homogenous light everywhere on the skin (head vertex, hand, etc.). For better light delivery homogeneity, plastic optical fibers (POFs) have been woven in textile in order to emit laterally the injected light. The previous studies confirmed that the light power could be locally controlled by modifying the radius of POF macro-bendings within the textile structure. The objective of this study is to optimize the distribution of macro-bendings over the LEF surface in order to increase the light intensity (mW/cm2), and to guarantee the best possible light deliver homogeneity over the LEF which are often contradictory. Fifteen experiments have been carried out with Doehlert experimental design involving Response Surface Methodology (RSM). The proposed models are fitted to the experimental data to enable the optimal set up of the warp yarns tensions.
D-optimal experimental designs to test for departure from additivity in a fixed-ratio mixture ray.
Coffey, Todd; Gennings, Chris; Simmons, Jane Ellen; Herr, David W
2005-12-01
Traditional factorial designs for evaluating interactions among chemicals in a mixture may be prohibitive when the number of chemicals is large. Using a mixture of chemicals with a fixed ratio (mixture ray) results in an economical design that allows estimation of additivity or nonadditive interaction for a mixture of interest. This methodology is extended easily to a mixture with a large number of chemicals. Optimal experimental conditions can be chosen that result in increased power to detect departures from additivity. Although these designs are used widely for linear models, optimal designs for nonlinear threshold models are less well known. In the present work, the use of D-optimal designs is demonstrated for nonlinear threshold models applied to a fixed-ratio mixture ray. For a fixed sample size, this design criterion selects the experimental doses and number of subjects per dose level that result in minimum variance of the model parameters and thus increased power to detect departures from additivity. An optimal design is illustrated for a 2:1 ratio (chlorpyrifos:carbaryl) mixture experiment. For this example, and in general, the optimal designs for the nonlinear threshold model depend on prior specification of the slope and dose threshold parameters. Use of a D-optimal criterion produces experimental designs with increased power, whereas standard nonoptimal designs with equally spaced dose groups may result in low power if the active range or threshold is missed. PMID:16162847
Multi-objective optimization design and experimental investigation of centrifugal fan performance
NASA Astrophysics Data System (ADS)
Zhang, Lei; Wang, Songling; Hu, Chenxing; Zhang, Qian
2013-11-01
Current studies of fan performance optimization mainly focus on two aspects: one is to improve the blade profile, and another is only to consider the influence of single impeller structural parameter on fan performance. However, there are few studies on the comprehensive effect of the key parameters such as blade number, exit stagger angle of blade and the impeller outlet width on the fan performance. The G4-73 backward centrifugal fan widely used in power plants is selected as the research object. Based on orthogonal design and BP neural network, a model for predicting the centrifugal fan performance parameters is established, and the maximum relative errors of the total pressure and efficiency are 0.974% and 0.333%, respectively. Multi-objective optimization of total pressure and efficiency of the fan is conducted with genetic algorithm, and the optimum combination of impeller structural parameters is proposed. The optimized parameters of blade number, exit stagger angle of blade and the impeller outlet width are seperately 14, 43.9°, and 21 cm. The experiments on centrifugal fan performance and noise are conducted before and after the installation of the new impeller. The experimental results show that with the new impeller, the total pressure of fan increases significantly in total range of the flow rate, and the fan efficiency is improved when the relative flow is above 75%, also the high efficiency area is broadened. Additionally, in 65% -100% relative flow, the fan noise is reduced. Under the design operating condition, total pressure and efficiency of the fan are improved by 6.91% and 0.5%, respectively. This research sheds light on the considering of comprehensive effect of impeller structrual parameters on fan performance, and a new impeller can be designed to satisfy the engineering demand such as energy-saving, noise reduction or solving air pressure insufficiency for power plants.
Martinello, Tiago; Kaneko, Telma Mary; Velasco, Maria Valéria Robles; Taqueda, Maria Elena Santos; Consiglieri, Vladi O
2006-09-28
The poor flowability and bad compressibility characteristics of paracetamol are well known. As a result, the production of paracetamol tablets is almost exclusively by wet granulation, a disadvantageous method when compared to direct compression. The development of a new tablet formulation is still based on a large number of experiments and often relies merely on the experience of the analyst. The purpose of this study was to apply experimental design methodology (DOE) to the development and optimization of tablet formulations containing high amounts of paracetamol (more than 70%) and manufactured by direct compression. Nineteen formulations, screened by DOE methodology, were produced with different proportions of Microcel 102, Kollydon VA 64, Flowlac, Kollydon CL 30, PEG 4000, Aerosil, and magnesium stearate. Tablet properties, except friability, were in accordance with the USP 28th ed. requirements. These results were used to generate plots for optimization, mainly for friability. The physical-chemical data found from the optimized formulation were very close to those from the regression analysis, demonstrating that the mixture project is a great tool for the research and development of new formulations. PMID:16806756
Navarrete-Bolaños, José Luis; Jiménez-Islas, Hugo; Botello-Alvarez, Enrique; Rico-Martínez, Ramiro
2003-04-01
Endogenous microorganisms isolated from the marigold flower (Tagetes erecta) were studied to understand the events taking place during its ensilage. Studies of the cellulase enzymatic activity and the ensilage process were undertaken. In both studies, the use of approximate second-order models and multiple lineal regression, within the context of an experimental mixture design using the response surface methodology as optimization strategy, determined that the microorganisms Flavobacterium IIb, Acinetobacter anitratus, and Rhizopus nigricans are the most significant in marigold flower ensilage and exhibit high cellulase activity. A mixed culture comprised of 9.8% Flavobacterium IIb, 41% A. anitratus, and 49.2% R. nigricans used during ensilage resulted in an increased yield of total xanthophylls extracted of 24.94 g/kg of dry weight compared with 12.92 for the uninoculated control ensilage. PMID:12670157
Wang, Hsiu-Ju; Pan, Meng-Chun; Chang, Chao-Kai; Chang, Shu-Wei; Hsieh, Chang-Wei
2014-01-01
This study reports on the optimization of the extraction conditions of cordycepin from Cordyceps militaris by using ultrasonication. For this purpose, the orthogonal experimental design was used to investigate the effects of factors on the ultrasonic-assisted extraction (UAE). Four factors: extraction time (min), ethanol concentration (%), extraction temperature (°C) and extraction frequency (kHz), were studied. The results showed that the highest cordycepin yield of 7.04 mg/g (86.98% ± 0.23%) was obtained with an extraction time of 60 min, ethanol concentration of 50%, extraction temperature of 65 °C and extraction frequency of 56 kHz. It was found that the cordycepin extraction yield increased with the effect of ultrasonication during the extraction process. Therefore, UAE can be used as an alternative to conventional immersion extraction with respect to the recovery of cordycepin from C. militaris, with the advantages of shorter extraction time and reduced solvent consumption. PMID:25514223
NASA Astrophysics Data System (ADS)
Reimer, Joscha; Piwonski, Jaroslaw; Slawig, Thomas
2016-04-01
The statistical significance of any model-data comparison strongly depends on the quality of the used data and the criterion used to measure the model-to-data misfit. The statistical properties (such as mean values, variances and covariances) of the data should be taken into account by choosing a criterion as, e.g., ordinary, weighted or generalized least squares. Moreover, the criterion can be restricted onto regions or model quantities which are of special interest. This choice influences the quality of the model output (also for not measured quantities) and the results of a parameter estimation or optimization process. We have estimated the parameters of a three-dimensional and time-dependent marine biogeochemical model describing the phosphorus cycle in the ocean. For this purpose, we have developed a statistical model for measurements of phosphate and dissolved organic phosphorus. This statistical model includes variances and correlations varying with time and location of the measurements. We compared the obtained estimations of model output and parameters for different criteria. Another question is if (and which) further measurements would increase the model's quality at all. Using experimental design criteria, the information content of measurements can be quantified. This may refer to the uncertainty in unknown model parameters as well as the uncertainty regarding which model is closer to reality. By (another) optimization, optimal measurement properties such as locations, time instants and quantities to be measured can be identified. We have optimized such properties for additional measurement for the parameter estimation of the marine biogeochemical model. For this purpose, we have quantified the uncertainty in the optimal model parameters and the model output itself regarding the uncertainty in the measurement data using the (Fisher) information matrix. Furthermore, we have calculated the uncertainty reduction by additional measurements depending on time
Abul Kalam, Mohd; Khan, Abdul Arif; Khan, Shahanavaj; Almalik, Abdulaziz; Alshamsan, Aws
2016-06-01
Indomethacin chitosan nanoparticles (NPs) were developed by ionotropic gelation and optimized by concentrations of chitosan and tripolyphosphate (TPP) and stirring time by 3-factor 3-level Box-Behnken experimental design. Optimal concentration of chitosan (A) and TPP (B) were found 0.6mg/mL and 0.4mg/mL with 120min stirring time (C), with applied constraints of minimizing particle size (R1) and maximizing encapsulation efficiency (R2) and drug release (R3). Based on obtained 3D response surface plots, factors A, B and C were found to give synergistic effect on R1, while factor A has a negative impact on R2 and R3. Interaction of AB was negative on R1 and R2 but positive on R3. The factor AC was having synergistic effect on R1 and on R3, while the same combination had a negative effect on R2. The interaction BC was positive on the all responses. NPs were found in the size range of 321-675nm with zeta potentials (+25 to +32mV) after 6 months storage. Encapsulation, drug release, and content were in the range of 56-79%, 48-73% and 98-99%, respectively. In vitro drug release data were fitted in different kinetic models and pattern of drug release followed Higuchi-matrix type. PMID:26893052
Mahmood, Syed; Taher, Muhammad; Mandal, Uttam Kumar
2014-01-01
Raloxifene hydrochloride, a highly effective drug for the treatment of invasive breast cancer and osteoporosis in post-menopausal women, shows poor oral bioavailability of 2%. The aim of this study was to develop, statistically optimize, and characterize raloxifene hydrochloride-loaded transfersomes for transdermal delivery, in order to overcome the poor bioavailability issue with the drug. A response surface methodology experimental design was applied for the optimization of transfersomes, using Box-Behnken experimental design. Phospholipon® 90G, sodium deoxycholate, and sonication time, each at three levels, were selected as independent variables, while entrapment efficiency, vesicle size, and transdermal flux were identified as dependent variables. The formulation was characterized by surface morphology and shape, particle size, and zeta potential. Ex vivo transdermal flux was determined using a Hanson diffusion cell assembly, with rat skin as a barrier medium. Transfersomes from the optimized formulation were found to have spherical, unilamellar structures, with a homogeneous distribution and low polydispersity index (0.08). They had a particle size of 134±9 nM, with an entrapment efficiency of 91.00%±4.90%, and transdermal flux of 6.5±1.1 μg/cm2/hour. Raloxifene hydrochloride-loaded transfersomes proved significantly superior in terms of amount of drug permeated and deposited in the skin, with enhancement ratios of 6.25±1.50 and 9.25±2.40, respectively, when compared with drug-loaded conventional liposomes, and an ethanolic phosphate buffer saline. Differential scanning calorimetry study revealed a greater change in skin structure, compared with a control sample, during the ex vivo drug diffusion study. Further, confocal laser scanning microscopy proved an enhanced permeation of coumarin-6-loaded transfersomes, to a depth of approximately160 μM, as compared with rigid liposomes. These ex vivo findings proved that a raloxifene hydrochloride
Mahmood, Syed; Taher, Muhammad; Mandal, Uttam Kumar
2014-01-01
Raloxifene hydrochloride, a highly effective drug for the treatment of invasive breast cancer and osteoporosis in post-menopausal women, shows poor oral bioavailability of 2%. The aim of this study was to develop, statistically optimize, and characterize raloxifene hydrochloride-loaded transfersomes for transdermal delivery, in order to overcome the poor bioavailability issue with the drug. A response surface methodology experimental design was applied for the optimization of transfersomes, using Box-Behnken experimental design. Phospholipon(®) 90G, sodium deoxycholate, and sonication time, each at three levels, were selected as independent variables, while entrapment efficiency, vesicle size, and transdermal flux were identified as dependent variables. The formulation was characterized by surface morphology and shape, particle size, and zeta potential. Ex vivo transdermal flux was determined using a Hanson diffusion cell assembly, with rat skin as a barrier medium. Transfersomes from the optimized formulation were found to have spherical, unilamellar structures, with a homogeneous distribution and low polydispersity index (0.08). They had a particle size of 134±9 nM, with an entrapment efficiency of 91.00%±4.90%, and transdermal flux of 6.5±1.1 μg/cm(2)/hour. Raloxifene hydrochloride-loaded transfersomes proved significantly superior in terms of amount of drug permeated and deposited in the skin, with enhancement ratios of 6.25±1.50 and 9.25±2.40, respectively, when compared with drug-loaded conventional liposomes, and an ethanolic phosphate buffer saline. Differential scanning calorimetry study revealed a greater change in skin structure, compared with a control sample, during the ex vivo drug diffusion study. Further, confocal laser scanning microscopy proved an enhanced permeation of coumarin-6-loaded transfersomes, to a depth of approximately160 μM, as compared with rigid liposomes. These ex vivo findings proved that a raloxifene hydrochloride
NASA Astrophysics Data System (ADS)
Lewis, Jeffrey; Sjöstrom, Jan
2010-06-01
Soil column experiments in both the saturated and unsaturated regimes are widely used for applied and theoretical studies in such diverse fields as transport model evaluation, fate and transport of pesticides, explosives, microbes, heavy metals and non aqueous phase liquids, and for evapotranspiration studies. The apparent simplicity of constructing soil columns conceals a number of technical issues which can seriously affect the outcome of an experiment, such as the presence or absence of macropores, artificial preferential flow paths, non-ideal infiltrate injection and unrealistic moisture regimes. This review examines the literature to provide an analysis of the state of the art for constructing both saturated and unsaturated soil columns. Common design challenges are discussed and best practices for potential solutions are presented. This article discusses both basic principles and the practical advantages and disadvantages of various experimental approaches. Both repacked and monolith-type columns are discussed. The information in this review will assist soil scientists, hydrogeologists and environmental professionals in optimizing the construction and operation of soil column experiments in order to achieve their objectives, while avoiding serious design flaws which can compromise the integrity of their results.
Celani de Souza, Helder Jose; Moyses, Cinthia B; Pontes, Fabrício J; Duarte, Roberto N; Sanches da Silva, Carlos Eduardo; Alberto, Fernando Lopes; Ferreira, Ubirajara R; Silva, Messias Borges
2011-01-01
Two mutations - Factor V Leiden (1691G > A) and the 20210G > A on the Prothrombin gene - are key risk factors for a frequent and potentially fatal disorder called Venous Thromboembolism. These molecular alterations can be investigated using real-time Polymerase Chain Reaction (PCR) with Fluorescence Resonance Energy Transfer (FRET) probes and distinct DNA pools for both factors. The objective of this paper is to present an application of Taguchi Experimental Design Method to determine the best parameters adjustment of a Molecular Assays Process in order to obtain the best diagnostic result for Venous Thromboembolism investigation. The complete process contains six three-level factors which usually demands 729 experiments to obtain the final result, if using a Full Factorial Array. In this research, a Taguchi L27 Orthogonal Array is chosen to optimize the analysis and reduce the number of experiments to 27 without degrading the final result accuracy. The application of this method can lessen the time and cost necessary to achieve the best operation condition for a required performance. The results is proven in practice and confirmed that the Taguchi method can really offer a good approach for clinical assay efficiency and effectiveness improvement even though the clinical diagnostics can be based on the use of qualitative techniques. PMID:21867748
NASA Astrophysics Data System (ADS)
Hu, Enzhu; Bartsev, Sergey I.; Zhao, Ming; Liu, Professor Hong
The conceptual scheme of an experimental bioregenerative life support system (BLSS) for planetary exploration was designed, which consisted of four elements - human metabolism, higher plants, silkworms and waste treatment. 15 kinds of higher plants, such as wheat, rice, soybean, lettuce, mulberry, et al., were selected as regenerative component of BLSS providing the crew with air, water, and vegetable food. Silkworms, which producing animal nutrition for crews, were fed by mulberry-leaves during the first three instars, and lettuce leaves last two instars. The inedible biomass of higher plants, human wastes and silkworm feces were composted into soil like substrate, which can be reused by higher plants cultivation. Salt, sugar and some household material such as soap, shampoo would be provided from outside. To support the steady state of BLSS the same amount and elementary composition of dehydrated wastes were removed periodically. The balance of matter flows between BLSS components was described by the system of algebraic equations. The mass flows between the components were optimized by EXCEL spreadsheets and using Solver. The numerical method used in this study was Newton's method.
Trovó, Alam G; Silva, Tatiane F S; Gomes, Oswaldo; Machado, Antonio E H; Neto, Waldomiro Borges; Muller, Paulo S; Daniel, Daniela
2013-01-01
The degradation of caffeine in different kind of effluents, via photo-Fenton process, was investigated in lab-scale and in a solar pilot plant. The treatment conditions (caffeine, Fe(2+) and H(2)O(2) concentrations) were defined by experimental design. The optimized conditions for each variable, obtained using the response factor (% mineralization), were: 52.0 mg L(-1)caffeine, 10.0 mg L(-1)Fe(2+) and 42.0 mg L(-1)H(2)O(2) (replaced in kinetic experiments). Under these conditions, in ultrapure water (UW), the caffeine concentration reached the quantitation limit (0.76 mg L(-1)) after 20 min, and 78% of mineralization was obtained respectively after 120 min of reaction. Using the same conditions, the matrix influence (surface water - SW and sewage treatment plant effluent - STP) on caffeine degradation was also evaluated. The total removal of caffeine in SW was reached at the same time in UW (after 20 min), while 40 min were necessary in STP. Although lower mineralization rates were verified for high organic load, under the same operational conditions, less H(2)O(2) was necessary to mineralize the dissolved organic carbon as the initial organic load increases. A high efficiency of the photo-Fenton process was also observed in caffeine degradation by solar photocatalysis using a CPC reactor, as well as intermediates of low toxicity, demonstrating that photo-Fenton process can be a viable alternative for caffeine removal in wastewater. PMID:22795305
Numerical and Experimental Approach for the Optimal Design of a Dual Plate Under Ballistic Impact
NASA Astrophysics Data System (ADS)
Yoo, Jeonghoon; Chung, Dong-Teak; Park, Myung Soo
To predict the behavior of a dual plate composed of 5052-aluminum and 1002-cold rolled steel under ballistic impact, numerical and experimental approaches are attempted. For the accurate numerical simulation of the impact phenomena, the appropriate selection of the key parameter values based on numerical or experimental tests are critical. This study is focused on not only the optimization technique using the numerical simulation but also numerical and experimental procedures to obtain the required parameter values in the simulation. The Johnson-Cook model is used to simulate the mechanical behaviors, and the simplified experimental and the numerical approaches are performed to obtain the material properties of the model. The element erosion scheme for the robust simulation of the ballistic impact problem is applied by adjusting the element erosion criteria of each material based on numerical and experimental results. The adequate mesh size and the aspect ratio are chosen based on parametric studies. Plastic energy is suggested as a response representing the strength of the plate for the optimization under dynamic loading. Optimized thickness of the dual plate is obtained to resist the ballistic impact without penetration as well as to minimize the total weight.
Kośmider, Alicja; Białas, Wojciech; Kubiak, Piotr; Drożdżyńska, Agnieszka; Czaczyk, Katarzyna
2012-02-01
A two-step statistical experimental design was employed to optimize the medium for vitamin B(12) production from crude glycerol by Propionibacterium freudenreichii ssp. shermanii. In the first step, using Plackett-Burman design, five of 13 tested medium components (calcium pantothenate, NaH(2)PO(4)·2H(2)O, casein hydrolysate, glycerol and FeSO(4)·7H(2)O) were identified as factors having significant influence on vitamin production. In the second step, a central composite design was used to optimize levels of medium components selected in the first step. Valid statistical models describing the influence of significant factors on vitamin B(12) production were established for each optimization phase. The optimized medium provided a 93% increase in final vitamin concentration compared to the original medium. PMID:22178491
Optimal experimental design for nano-particle atom-counting from high-resolution STEM images.
De Backer, A; De Wael, A; Gonnissen, J; Van Aert, S
2015-04-01
In the present paper, the principles of detection theory are used to quantify the probability of error for atom-counting from high resolution scanning transmission electron microscopy (HR STEM) images. Binary and multiple hypothesis testing have been investigated in order to determine the limits to the precision with which the number of atoms in a projected atomic column can be estimated. The probability of error has been calculated when using STEM images, scattering cross-sections or peak intensities as a criterion to count atoms. Based on this analysis, we conclude that scattering cross-sections perform almost equally well as images and perform better than peak intensities. Furthermore, the optimal STEM detector design can be derived for atom-counting using the expression for the probability of error. We show that for very thin objects LAADF is optimal and that for thicker objects the optimal inner detector angle increases. PMID:25499018
Uysal, Ersin; Akcan, Nurullah; Baysal, Zübeyde; Uyar, Fikret
2011-01-01
In this study, the Taguchi experimental design was applied to optimize the conditions for α-amylase production by Bacillus subtilis RSKK96, which was purchased from Refik Saydam Hifzissihha Industry (RSHM). Four factors, namely, carbon source, nitrogen source, amino acid, and fermentation time, each at four levels, were selected, and an orthogonal array layout of L(16) (4(5)) was performed. The model equation obtained was validated experimentally at maximum casein (1%), corn meal (1%), and glutamic acid (0.01%) concentrations with incubation time to 72 h in the presence of 1% inoculum density. Point prediction of the design showed that maximum α-amylase production of 503.26 U/mg was achieved under optimal experimental conditions. PMID:21229466
Design optimization and experimental testing of the High-Flux Test Module of IFMIF
NASA Astrophysics Data System (ADS)
Leichtle, D.; Arbeiter, F.; Dolensky, B.; Fischer, U.; Gordeev, S.; Heinzel, V.; Ihli, T.; Moeslang, A.; Simakov, S. P.; Slobodchuk, V.; Stratmanns, E.
2009-04-01
The design of the High-Flux Test Module of the International Fusion Material Irradiation Facility has been developed continuously in the past few years. The present paper highlights recent design achievements, including a thorough state-of-the-art validation assessment of CFD tools and models. Along with design related analyses exercises on manufacturing procedures have been performed. Recommendations for the use of container, rig, and capsule materials as well as recent progress in brazing of electrical heaters are discussed. A test matrix starting from High-Flux Test Module compartments, i.e. segments of the full module, with heated dummy rigs up to the full-scale module with instrumented irradiation rigs has been developed and the appropriate helium gas loop has been designed conceptually. A roadmap of the envisaged experimental activities is presented in accordance with the test loop facility construction and mock-up design and fabrication schedules.
A Resampling Based Approach to Optimal Experimental Design for Computer Analysis of a Complex System
Rutherford, Brian
1999-08-04
The investigation of a complex system is often performed using computer generated response data supplemented by system and component test results where possible. Analysts rely on an efficient use of limited experimental resources to test the physical system, evaluate the models and to assure (to the extent possible) that the models accurately simulate the system order investigation. The general problem considered here is one where only a restricted number of system simulations (or physical tests) can be performed to provide additional data necessary to accomplish the project objectives. The levels of variables used for defining input scenarios, for setting system parameters and for initializing other experimental options must be selected in an efficient way. The use of computer algorithms to support experimental design in complex problems has been a topic of recent research in the areas of statistics and engineering. This paper describes a resampling based approach to form dating this design. An example is provided illustrating in two dimensions how the algorithm works and indicating its potential on larger problems. The results show that the proposed approach has characteristics desirable of an algorithmic approach on the simple examples. Further experimentation is needed to evaluate its performance on larger problems.
An experimental evaluation of a helicopter rotor section designed by numerical optimization
NASA Technical Reports Server (NTRS)
Hicks, R. M.; Mccroskey, W. J.
1980-01-01
The wind tunnel performance of a 10-percent thick helicopter rotor section design by numerical optimization is presented. The model was tested at Mach number from 0.2 to 0.84 with Reynolds number ranging from 1,900,000 at Mach 0.2 to 4,000,000 at Mach numbers above 0.5. The airfoil section exhibited maximum lift coefficients greater than 1.3 at Mach numbers below 0.45 and a drag divergence Mach number of 0.82 for lift coefficients near 0. A moderate 'drag creep' is observed at low lift coefficients for Mach numbers greater than 0.6.
NASA Astrophysics Data System (ADS)
Russo, S.; Krastev, V. K.; Jannelli, E.; Falcucci, G.
2016-06-01
In this work, the design and the optimization of an experimental test bench for the experimental characterization of impulsive water-entry problems are presented. Currently, the majority of the experimental apparatus allow impact test only in specific conditions. Our test bench allows for testing of rigid and compliant bodies and allows performing experiments on floating or sinking structures, in free-fall, or under dynamic motion control. The experimental apparatus is characterized by the adoption of accelerometers, encoders, position sensors and, above all, FBG (fiber Bragg grating) sensors that, together with a high speed camera, provide accurate and fast data acquisitions for the dissection of structural deformations and hydrodynamic loadings under a broad set of experimental conditions.
NASA Astrophysics Data System (ADS)
Sohn, Jung Woo; Jeon, Juncheol; Nguyen, Quoc Hung; Choi, Seung-Bok
2015-08-01
In this paper, a disc-type magneto-rheological (MR) brake is designed for a mid-sized motorcycle and its performance is experimentally evaluated. The proposed MR brake consists of an outer housing, a rotating disc immersed in MR fluid, and a copper wire coiled around a bobbin to generate a magnetic field. The structural configuration of the MR brake is first presented with consideration of the installation space for the conventional hydraulic brake of a mid-sized motorcycle. The design parameters of the proposed MR brake are optimized to satisfy design requirements such as the braking torque, total mass of the MR brake, and cruising temperature caused by the magnetic-field friction of the MR fluid. In the optimization procedure, the braking torque is calculated based on the Herschel-Bulkley rheological model, which predicts MR fluid behavior well at high shear rate. An optimization tool based on finite element analysis is used to obtain the optimized dimensions of the MR brake. After manufacturing the MR brake, mechanical performances regarding the response time, braking torque and cruising temperature are experimentally evaluated.
NASA Astrophysics Data System (ADS)
Singh, Harinder J.; Hu, Wei; Wereley, Norman M.; Glass, William
2014-12-01
A linear stroke adaptive magnetorheological energy absorber (MREA) was designed, fabricated and tested for intense impact conditions with piston velocities up to 8 m s-1. The performance of the MREA was characterized using dynamic range, which is defined as the ratio of maximum on-state MREA force to the off-state MREA force. Design optimization techniques were employed in order to maximize the dynamic range at high impact velocities such that MREA maintained good control authority. Geometrical parameters of the MREA were optimized by evaluating MREA performance on the basis of a Bingham-plastic analysis incorporating minor losses (BPM analysis). Computational fluid dynamics and magnetic FE analysis were conducted to verify the performance of passive and controllable MREA force, respectively. Subsequently, high-speed drop testing (0-4.5 m s-1 at 0 A) was conducted for quantitative comparison with the numerical simulations. Refinements to the nonlinear BPM analysis were carried out to improve prediction of MREA performance.
Zhao, Ying-Zheng; Lu, Cui-Tao; Mei, Xin-Guo
2008-08-01
Sonogenic microbubble agent is a newly developed drug targeting delivery system, which uses ultrasonic beam to enhance the delivery of drug and gene to targeted cells and tissues. In this paper, the preparation of sonogenic phospholipids-based microbubbles was optimized by using central composite experimental design (CCD) and response surface methodology (RSM). Hydrogenated egg phosphatidylcholine (EPC), Tween 80 and polyethylene glycol 1500 (PEG 1500) were important components affecting the concentration of 2 - 8 microm microbubbles in the preparation. The combined effects of these three factors were analyzed by CCD and optimized by RSM. Evaluation variable was the concentration of 2 - 8 microm microbubbles. Overall desirability was fitted to a second-order polynomial equation, through which three dimensional response surface graphs were produced. Optimal experimental conditions were selected from the stationary point of the response surfaces. The stability of the sonogenic phospholipids-based microbubbles by the optimal formulation was investigated by accelerated experiment. The contrast effect in vivo of the optimal formulation was investigated. Foreign market product SonoVue was used as the control. From the results, all the three factors had positive effects on the concentration of 2 - 8 microm microbubbles. The optimal condition in the preparation of phospholipids-based microbubbles was obtained as following: EPC 8.35 mg, Tween 80 21.68 mg and PEG 1500 201 mg. The mean value of the concentration of 2 - 8 microm microbubbles in rechecking experiment reached 8.60 x 10(9) x mL(-1). From the accelerated experiment, phospholipids-based microbubbles showed good physical stability. The intensity (relative unit) and duration of the contrast effect by the optimal formulation were 4.47 +/- 0.15 and (302 +/- 7) s respectively, which showed little difference with foreign market product SonoVue [4.28 +/- 0.13, (309 +/- 8) s]. The optimal formulation selected by CCD and
Sanchez, Gaëtan; Lecaignard, Françoise; Otman, Anatole; Maby, Emmanuel; Mattout, Jérémie
2016-01-01
The relatively young field of Brain-Computer Interfaces has promoted the use of electrophysiology and neuroimaging in real-time. In the meantime, cognitive neuroscience studies, which make extensive use of functional exploration techniques, have evolved toward model-based experiments and fine hypothesis testing protocols. Although these two developments are mostly unrelated, we argue that, brought together, they may trigger an important shift in the way experimental paradigms are being designed, which should prove fruitful to both endeavors. This change simply consists in using real-time neuroimaging in order to optimize advanced neurocognitive hypothesis testing. We refer to this new approach as the instantiation of an Active SAmpling Protocol (ASAP). As opposed to classical (static) experimental protocols, ASAP implements online model comparison, enabling the optimization of design parameters (e.g., stimuli) during the course of data acquisition. This follows the well-known principle of sequential hypothesis testing. What is radically new, however, is our ability to perform online processing of the huge amount of complex data that brain imaging techniques provide. This is all the more relevant at a time when physiological and psychological processes are beginning to be approached using more realistic, generative models which may be difficult to tease apart empirically. Based upon Bayesian inference, ASAP proposes a generic and principled way to optimize experimental design adaptively. In this perspective paper, we summarize the main steps in ASAP. Using synthetic data we illustrate its superiority in selecting the right perceptual model compared to a classical design. Finally, we briefly discuss its future potential for basic and clinical neuroscience as well as some remaining challenges. PMID:27458364
Ben Taheur, Fadia; Fdhila, Kais; Elabed, Hamouda; Bouguerra, Amel; Kouidhi, Bochra; Bakhrouf, Amina; Chaieb, Kamel
2016-04-01
Three bacterial strains (TE1, TD3 and FB2) were isolated from date palm (degla), pistachio and barley. The presence of nitrate reductase (narG) and nitrite reductase (nirS and nirK) genes in the selected strains was detected by PCR technique. Molecular identification based on 16S rDNA sequencing method was applied to identify positive strains. In addition, the D-optimal mixture experimental design was used to optimize the optimal formulation of probiotic bacteria for denitrification process. Strains harboring denitrification genes were identified as: TE1, Agrococcus sp LN828197; TD3, Cronobacter sakazakii LN828198 and FB2, Pedicoccus pentosaceus LN828199. PCR results revealed that all strains carried the nirS gene. However only C. sakazakii LN828198 and Agrococcus sp LN828197 harbored the nirK and the narG genes respectively. Moreover, the studied bacteria were able to form biofilm on abiotic surfaces with different degree. Process optimization showed that the most significant reduction of nitrate was 100% with 14.98% of COD consumption and 5.57 mg/l nitrite accumulation. Meanwhile, the response values were optimized and showed that the most optimal combination was 78.79% of C. sakazakii LN828198 (curve value), 21.21% of P. pentosaceus LN828199 (curve value) and absence (0%) of Agrococcus sp LN828197 (curve value). PMID:26893037
Golabchifar, Ali-Akbar; Rouini, Mohammad-Reza; Shafaghi, Bijan; Rezaee, Saeed; Foroumadi, Alireza; Khoshayand, Mohammad-Reza
2011-10-15
A simple, rapid and specific HPLC method has been developed and validated for the simultaneous determination of imatinib, a tyrosine kinase inhibitor, and its major metabolite, CGP74588, in human plasma. The optimization of the HPLC procedure involved several variables, of which the influences of each was studied. After a series of preliminary-screening experiments, the composition of the mobile phase and the pH of the added buffer solution were set as the investigated variables, while the resolution between imatinib and CGP74588 peaks, the retention time and the imatinib peak width were chosen as the dependent variables. Applying D-optimal design, the optimal chromatographic conditions for the separation were defined. The method proved to show good agreement between the experimental data and predictive values throughout the studied parameter range. The optimum assay conditions were achieved with a Chromolith™ Performance RP-8e 100 mm × 4.6 mm column and a mixture of methanol/acetonitrile/triethylamine/diammonium hydrogen phosphate (pH 6.25, 0.048 mol L(-1)) (20:20:0.1:59.9, v/v/v/v) as the mobile phase at a flow rate of 2 mL min(-1) and detection wavelength of 261 nm. The run time was less than 5 min, which is much shorter than the previously optimized methods. The optimized method was validated according to FDA guidelines to confirm specificity, linearity, accuracy and precision. PMID:21962649
Gao, Ping; Witt, Martha J; Haskell, Roy J; Zamora, Kathryn M; Shifflett, John R
2004-08-01
Response surface methodology (RSM) was applied to optimize the self-emulsifying drug delivery system (SEDDS) containing 25% (w/w) Drug A, a model drug with a high lipophilicity and low water solubility. The key objective of this study was to identify an optimal SEDDS formulation that: 1) possesses a minimum concentration of the surfactant and a maximum concentration of lipid and 2) generates a fine emulsion and eliminates large size droplets (> or = 1 microm) upon dilution with an aqueous medium. Three ingredient variables [PEG 400, Cremophor EL, and a mixture of glycerol dioleate (GDO), and glycerol monooleate (GMO)] were included in the experimental design, while keeping the other ingredients at a fixed level (25% Drug A, 6% ethanol, 3% propylene glycol, 4% water, and 2% tromethamine) in the SEDDS formulation. Dispersion performance of these formulations upon dilution with a simulated gastrointestinal fluid was measured, and the population of the large droplets was used as the primary response for statistical modeling. The results of this mixture study revealed significant interactions among the three ingredients, and their individual levels in the formulation collectively dictated the dispersion performance. The fitted response surface model predicted an optimal region of the SEDDS formulation compositions that generate fine emulsions and essentially eliminates large droplets upon dilution. The predicted optimal 25% Drug A-SEDDS formulations with the levels of Cremophor EL ranging from 40-44%, GDO/GMO ranging from 10-13%, and PEG 400 ranging from 2.7-9.0% were selected and prepared. The dispersion experiment results confirmed the prediction of this model and identified potential optimal formulations for further development. This work demonstrates that RSM is an efficient approach for optimization of the SEDDS formulation. PMID:15458235
Candioti, Luciana Vera; De Zan, María M; Cámara, María S; Goicoechea, Héctor C
2014-06-01
A review about the application of response surface methodology (RSM) when several responses have to be simultaneously optimized in the field of analytical methods development is presented. Several critical issues like response transformation, multiple response optimization and modeling with least squares and artificial neural networks are discussed. Most recent analytical applications are presented in the context of analytLaboratorio de Control de Calidad de Medicamentos (LCCM), Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, C.C. 242, S3000ZAA Santa Fe, ArgentinaLaboratorio de Control de Calidad de Medicamentos (LCCM), Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, C.C. 242, S3000ZAA Santa Fe, Argentinaical methods development, especially in multiple response optimization procedures using the desirability function. PMID:24767454
Deruaz, D.; Bannier, A.; Pionchon, C.
1995-08-01
This paper deals with the optimal conditions for the detection of {sup 15}N determined using a four-factor experimental design from [2{sup 13}C,-1,3 {sup 15}N] caffeine measured with an atomic emission detector (AED) coupled to gas chromatography (GC). Owing to the capability of a photodiodes array, AED can simultaneously detect several elements using their specific emission lines within a wavelength range of 50 nm. So, the emissions of {sup 15}N and {sup 14}N are simultaneously detected at 420.17 nm and 421.46 nm respectively. Four independent experimental factors were tested (1) helium flow rate (plasma gas); (2) methane pressure (reactant gas); (3) oxygen pressure; (4) hydrogen pressure. It has been shown that these four gases had a significant influence on the analytical response of {sup 15}N. The linearity of the detection was determined using {sup 15}N amounts ranging from 1.52 pg to 19 ng under the optimal conditions obtained from the experimental design. The limit of detection was studied using different methods. The limits of detection of {sup 15}N was 1.9 pg/s according to the IUPAC method (International-Union of Pure and Applied Chemistry). The method proposed by Quimby and Sullivan gave a value of 2.3 pg/s and that of Oppenheimer gave a limit of 29 pg/s. For each determination, and internal standard: 1-isobutyl-3.7 dimethylxanthine was used. The results clearly demonstrate that GC AED is sensitive and selective enough to detect and measure {sup 15}N-labelled molecules after gas chromatographic separation.
Conceptual design optimization study
NASA Technical Reports Server (NTRS)
Hollowell, S. J.; Beeman, E. R., II; Hiyama, R. M.
1990-01-01
The feasibility of applying multilevel functional decomposition and optimization techniques to conceptual design of advanced fighter aircraft was investigated. Applying the functional decomposition techniques to the conceptual design phase appears to be feasible. The initial implementation of the modified design process will optimize wing design variables. A hybrid approach, combining functional decomposition techniques for generation of aerodynamic and mass properties linear sensitivity derivatives with existing techniques for sizing mission performance and optimization, is proposed.
Experimental validation of structural optimization methods
NASA Technical Reports Server (NTRS)
Adelman, Howard M.
1992-01-01
The topic of validating structural optimization methods by use of experimental results is addressed. The need for validating the methods as a way of effecting a greater and an accelerated acceptance of formal optimization methods by practicing engineering designers is described. The range of validation strategies is defined which includes comparison of optimization results with more traditional design approaches, establishing the accuracy of analyses used, and finally experimental validation of the optimization results. Examples of the use of experimental results to validate optimization techniques are described. The examples include experimental validation of the following: optimum design of a trussed beam; combined control-structure design of a cable-supported beam simulating an actively controlled space structure; minimum weight design of a beam with frequency constraints; minimization of the vibration response of helicopter rotor blade; minimum weight design of a turbine blade disk; aeroelastic optimization of an aircraft vertical fin; airfoil shape optimization for drag minimization; optimization of the shape of a hole in a plate for stress minimization; optimization to minimize beam dynamic response; and structural optimization of a low vibration helicopter rotor.
Silva, Karen T.; Leão, Pedro E.; Abreu, Fernanda; López, Jimmy A.; Gutarra, Melissa L.; Farina, Marcos; Bazylinski, Dennis A.; Freire, Denise M. G.
2013-01-01
The growth and magnetosome production of the marine magnetotactic vibrio Magnetovibrio blakemorei strain MV-1 were optimized through a statistics-based experimental factorial design. In the optimized growth medium, maximum magnetite yields of 64.3 mg/liter in batch cultures and 26 mg/liter in a bioreactor were obtained. PMID:23396329
Patris, Stéphanie; Vandeput, Marie; Kenfack, Gersonie Momo; Mertens, Dominique; Dejaegher, Bieke; Kauffmann, Jean-Michel
2016-03-15
An immunoassay for the determination of anti-tetani antibodies has been developed using a screen printed electrode (SPE) as solid support for toxoid (antigen) immobilization. The assay was performed in guinea pig serum. The immunoreaction and the subsequent amperometric detection occurred directly onto the SPE surface. The assay consisted of spiking the anti-tetani sample directly onto the toxoid modified SPE, and then a second antibody, i.e. a HRP-labeled anti-immunoglobulin G, was deposited onto the biosensor. Subsequent amperometric detection was realized by spiking 10 µL of a hydroquinone (HQ) solution into 40 µL of buffer solution containing hydrogen peroxide. An experimental design approach was implemented for the optimization of the immunoassay. The variables of interest, such as bovine serum albumin (BSA) concentration, incubation times and labeled antibody dilution, were optimized with the aid of the response surface methodology using a circumscribed central composite design (CCCD). It was observed that two factors exhibited the greatest impact on the response, i.e. the anti-tetani incubation time and the dilution factor of the labeled antibody. It was discovered that in order to maximize the response, the dilution factor should be small, while the anti-tetani antibody incubation time should be long. The BSA concentration and the HRP-anti-IgG incubation had very limited influence. Under the optimized conditions, the immunoassay had a limit of detection of 0.011 IU/mL and a limit of quantification of 0.012 IU/mL. These values were below the protective human antibody limit of 0.06 IU/mL. PMID:26454827
Heterogeneity of the gut microbiome in mice: guidelines for optimizing experimental design
Laukens, Debby; Brinkman, Brigitta M.; Raes, Jeroen; De Vos, Martine; Vandenabeele, Peter
2015-01-01
Targeted manipulation of the gut flora is increasingly being recognized as a means to improve human health. Yet, the temporal dynamics and intra- and interindividual heterogeneity of the microbiome represent experimental limitations, especially in human cross-sectional studies. Therefore, rodent models represent an invaluable tool to study the host–microbiota interface. Progress in technical and computational tools to investigate the composition and function of the microbiome has opened a new era of research and we gradually begin to understand the parameters that influence variation of host-associated microbial communities. To isolate true effects from confounding factors, it is essential to include such parameters in model intervention studies. Also, explicit journal instructions to include essential information on animal experiments are mandatory. The purpose of this review is to summarize the factors that influence microbiota composition in mice and to provide guidelines to improve the reproducibility of animal experiments. PMID:26323480
L'Hocine, Lamia; Pitre, Mélanie
2016-03-01
A D-optimal design was constructed to optimize allergen extraction efficiency simultaneously from roasted, non-roasted, defatted, and non-defatted almond, hazelnut, peanut, and pistachio flours using three non-denaturing aqueous (phosphate, borate, and carbonate) buffers at various conditions of ionic strength, buffer-to-protein ratio, extraction temperature, and extraction duration. Statistical analysis showed that roasting and non-defatting significantly lowered protein recovery for all nuts. Increasing the temperature and the buffer-to-protein ratio during extraction significantly increased protein recovery, whereas increasing the extraction time had no significant impact. The impact of the three buffers on protein recovery varied significantly among the nuts. Depending on the extraction conditions, protein recovery varied from 19% to 95% for peanut, 31% to 73% for almond, 17% to 64% for pistachio, and 27% to 88% for hazelnut. A modulation by the buffer type and ionic strength of protein and immunoglobuline E binding profiles of extracts was evidenced, where high protein recovery levels did not always correlate with high immunoreactivity. PMID:26471618
D-OPTIMAL EXPERIMENTAL DESIGNS TO TEST FOR DEPARTURE FROM ADDITIVITY IN A FIXED-RATIO MIXTURE RAY.
Humans are exposed to mixtures of environmental compounds. A regulatory assumption is that the mixtures of chemicals act in an additive manner. However, this assumption requires experimental validation. Traditional experimental designs (full factorial) require a large number of e...
NASA Astrophysics Data System (ADS)
Yu, Long; Druckenbrod, Markus; Greve, Martin; Wang, Ke-qi; Abdel-Maksoud, Moustafa
2015-10-01
A fully automated optimization process is provided for the design of ducted propellers under open water conditions, including 3D geometry modeling, meshing, optimization algorithm and CFD analysis techniques. The developed process allows the direct integration of a RANSE solver in the design stage. A practical ducted propeller design case study is carried out for validation. Numerical simulations and open water tests are fulfilled and proved that the optimum ducted propeller improves hydrodynamic performance as predicted.
NASA Astrophysics Data System (ADS)
Girish, B. M.; Satish, B. M.; Sarapure, Sadanand; Basawaraj
2016-06-01
In the present paper, the statistical investigation on wear behavior of magnesium alloy (AZ91) hybrid metal matrix composites using Taguchi technique has been reported. The composites were reinforced with SiC and graphite particles of average size 37 μm. The specimens were processed by stir casting route. Dry sliding wear of the hybrid composites were tested on a pin-on-disk tribometer under dry conditions at different normal loads (20, 40, and 60 N), sliding speeds (1.047, 1.57, and 2.09 m/s), and composition (1, 2, and 3 wt pct of each of SiC and graphite). The design of experiments approach using Taguchi technique was employed to statistically analyze the wear behavior of hybrid composites. Signal-to-noise ratio and analysis of variance were used to investigate the influence of the parameters on the wear rate.
Kim, Nam Ah; An, In Bok; Lee, Sang Yeol; Park, Eun-Seok; Jeong, Seong Hoon
2012-09-01
In this study, the structural stability of hen egg white lysozyme in solution at various pH levels and in different types of buffers, including acetate, phosphate, histidine, and Tris, was investigated by means of differential scanning calorimetry (DSC). Reasonable pH values were selected from the buffer ranges and were analyzed statistically through design of experiment (DoE). Four factors were used to characterize the thermograms: calorimetric enthalpy (ΔH), temperature at maximum heat flux (T( m )), van't Hoff enthalpy (ΔH( V )), and apparent activation energy of protein solution (E(app)). It was possible to calculate E(app) through mathematical elaboration from the Lumry-Eyring model by changing the scan rate. The transition temperature of protein solution, T( m ), increased when the scan rate was faster. When comparing the T( m ), ΔH( V ), ΔH, and E(app) of lysozyme in various pH ranges and buffers with different priorities, lysozyme in acetate buffer at pH 4.767 (scenario 9) to pH 4.969 (scenario 11) exhibited the highest thermodynamic stability. Through this experiment, we found a significant difference in the thermal stability of lysozyme in various pH ranges and buffers and also a new approach to investigate the physical stability of protein by DoE. PMID:23054718
D-OPTIMAL EXPERIMENTAL DESIGNS TO TEST FOR DEPARTURE FROM ADDITIVITY IN A FIXED-RATIO MIXTURE RAY.
Traditional factorial designs for evaluating interactions among chemicals in a mixture are prohibitive when the number of chemicals is large. However, recent advances in statistically-based experimental design have made it easier to evaluate interactions involving many chemicals...
Propeller design by optimization
NASA Technical Reports Server (NTRS)
Rizk, M. H.; Jou, W.-H.
1986-01-01
The feasibility of designing propellers by an optimization procedure is investigated. A scheme, which solves the full potential flow equation about a propeller by line relaxation, is modified so that the iterative solutions of the flow equation and the design parameters are updated simultaneously. Some technical problems in using optimization for designing propellers with maximum efficiency are identified. Approaches for overcoming these problems are presented.
Hansborough, L.; Hamm, R.; Stovall, J.; Swenson, D.
1980-01-01
PIGMI (Pion Generator for Medical Irradiations) is a compact linear proton accelerator design, optimized for pion production and cancer treatment use in a hospital environment. Technology developed during a four-year PIGMI Prototype experimental program allows the design of smaller, less expensive, and more reliable proton linacs. A new type of low-energy accelerating structure, the radio-frequency quadrupole (RFQ) has been tested; it produces an exceptionally good-quality beam and allows the use of a simple 30-kV injector. Average axial electric-field gradients of over 9 MV/m have been demonstrated in a drift-tube linac (DTL) structure. Experimental work is underway to test the disk-and-washer (DAW) structure, another new type of accelerating structure for use in the high-energy coupled-cavity linac (CCL). Sufficient experimental and developmental progress has been made to closely define an actual PIGMI. It will consist of a 30-kV injector, and RFQ linac to a proton energy of 2.5 MeV, a DTL linac to 125 MeV, and a CCL linac to the final energy of 650 MeV. The total length of the accelerator is 133 meters. The RFQ and DTL will be driven by a single 440-MHz klystron; the CCL will be driven by six 1320-MHz klystrons. The peak beam current is 28 mA. The beam pulse length is 60 ..mu..s at a 60-Hz repetition rate, resulting in a 100-..mu..A average beam current. The total cost of the accelerator is estimated to be approx. $10 million.
NASA Astrophysics Data System (ADS)
Asghari, E.; Ashassi-Sorkhabi, H.; Ahangari, M.; Bagheri, R.
2016-04-01
Factors such as inhibitor concentration, solution hydrodynamics, and temperature influence the performance of corrosion inhibitor mixtures. The simultaneous studying of the impact of different factors is a time- and cost-consuming process. The use of experimental design methods can be useful in minimizing the number of experiments and finding local optimized conditions for factors under the investigation. In the present work, the inhibition performance of a three-component inhibitor mixture against corrosion of St37 steel rotating disk electrode, RDE, was studied. The mixture was composed of citric acid, lanthanum(III) nitrate, and tetrabutylammonium perchlorate. In order to decrease the number of experiments, the L16 Taguchi orthogonal array was used. The "control factors" were the concentration of each component and the rotation rate of RDE and the "response factor" was the inhibition efficiency. The scanning electron microscopy and energy dispersive x-ray spectroscopy techniques verified the formation of islands of adsorbed citrate complexes with lanthanum ions and insoluble lanthanum(III) hydroxide. From the Taguchi analysis results the mixture of 0.50 mM lanthanum(III) nitrate, 0.50 mM citric acid, and 2.0 mM tetrabutylammonium perchlorate under the electrode rotation rate of 1000 rpm was found as optimum conditions.
NASA Astrophysics Data System (ADS)
Ávila, Akie K.; Araujo, Thiago O.; Couto, Paulo R. G.; Borges, Renata M. H.
2005-10-01
In general, research experimentation is often used mainly when new methodologies are being developed or existing ones are being improved. The characteristics of any method depend on its factors or components. The planning techniques and analysis of experiments are basically used to improve the analytical conditions of methods, to reduce experimental labour with the minimum of tests and to optimize the use of resources (reagents, time of analysis, availability of the equipment, operator time, etc). These techniques are applied by the identification of variables (control factors) of a process that have the most influence on the response of the parameters of interest, by attributing values to the influential variables of the process in order that the variability of response can be minimum, or the obtained value (quality parameter) be very close to the nominal value, and by attributing values to the influential variables of the process so that the effects of uncontrollable variables can be reduced. In this central composite design (CCD), four permanent modifiers (Pd, Ir, W and Rh) and one combined permanent modifier W+Ir were studied. The study selected two factors: pyrolysis and atomization temperatures at five different levels for all the possible combinations. The pyrolysis temperatures with different permanent modifiers varied from 600 °C to 1600 °C with hold times of 25 s, while atomization temperatures ranged between 1900 °C and 2280 °C. The characteristic masses for As were in the range of 31 pg to 81 pg. Assuming the best conditions obtained on CCD, it was possible to estimate the measurement uncertainty of As determination in water samples. The results showed that considering the main uncertainty sources such as the repetitivity of measurement inherent in the equipment, the calibration curve which evaluates the adjustment of the mathematical model to the results and the calibration standards concentrations, the values obtained were similar to international
NASA Technical Reports Server (NTRS)
Allan, Brian; Owens, Lewis
2010-01-01
In support of the Blended-Wing-Body aircraft concept, a new flow control hybrid vane/jet design has been developed for use in a boundary-layer-ingesting (BLI) offset inlet in transonic flows. This inlet flow control is designed to minimize the engine fan-face distortion levels and the first five Fourier harmonic half amplitudes while maximizing the inlet pressure recovery. This concept represents a potentially enabling technology for quieter and more environmentally friendly transport aircraft. An optimum vane design was found by minimizing the engine fan-face distortion, DC60, and the first five Fourier harmonic half amplitudes, while maximizing the total pressure recovery. The optimal vane design was then used in a BLI inlet wind tunnel experiment at NASA Langley's 0.3-meter transonic cryogenic tunnel. The experimental results demonstrated an 80-percent decrease in DPCPavg, the reduction in the circumferential distortion levels, at an inlet mass flow rate corresponding to the middle of the operational range at the cruise condition. Even though the vanes were designed at a single inlet mass flow rate, they performed very well over the entire inlet mass flow range tested in the wind tunnel experiment with the addition of a small amount of jet flow control. While the circumferential distortion was decreased, the radial distortion on the outer rings at the aerodynamic interface plane (AIP) increased. This was a result of the large boundary layer being distributed from the bottom of the AIP in the baseline case to the outer edges of the AIP when using the vortex generator (VG) vane flow control. Experimental results, as already mentioned, showed an 80-percent reduction of DPCPavg, the circumferential distortion level at the engine fan-face. The hybrid approach leverages strengths of vane and jet flow control devices, increasing inlet performance over a broader operational range with significant reduction in mass flow requirements. Minimal distortion level requirements
NASA Astrophysics Data System (ADS)
Kaviani Darani, Masoume; Bastani, Saeed; Ghahari, Mehdi; Kardar, Pooneh
2015-11-01
Ultraviolet (UV) emissions of hydrothermally synthesized NaYF4: Yb3+, Tm3+ upconversion crystals were optimized using the response surface methodology experimental design. In these experimental designs, 9 runs, two factors namely (1) Tm3+ ion concentration, and (2) pH value were investigated using 3 different ligands. Introducing UV upconversion emissions as responses, their intensity were separately maximized. Analytical methods such as XRD, SEM, and FTIR could be used to study crystal structure, morphology, and fluorescent spectroscopy in order to obtain luminescence properties. From the photo-luminescence spectra, emissions centered at 347, 364, 452, 478, 648 and 803 nm were observed. Some results show that increasing each DOE factor up to an optimum value resulted in an increase in emission intensity, followed by reduction. To optimize UV emission, as a final result to the UV emission optimization, each design had a suggestion.
Rusconi, Patrice; Marelli, Marco; D'Addario, Marco; Russo, Selena; Cherubini, Paolo
2014-05-01
Evidence evaluation is a crucial process in many human activities, spanning from medical diagnosis to impression formation. The present experiments investigated which, if any, normative model best conforms to people's intuition about the value of the obtained evidence. Psychologists, epistemologists, and philosophers of science have proposed several models to account for people's intuition about the utility of the obtained evidence with respect either to a focal hypothesis or to a constellation of hypotheses. We pitted against each other the so-called optimal-experimental-design models (i.e., Bayesian diagnosticity, log₁₀ diagnosticity, information gain, Kullback-Leibler distance, probability gain, and impact) and measures L and Z to compare their ability to describe humans' intuition about the value of the obtained evidence. Participants received words-and-numbers scenarios concerning 2 hypotheses and binary features. They were asked to evaluate the utility of "yes" and "no" answers to questions about some features possessed in different proportions (i.e., the likelihoods) by 2 types of extraterrestrial creatures (corresponding to 2 mutually exclusive and exhaustive hypotheses). Participants evaluated either how an answer was helpful or how an answer decreased/increased their beliefs with respect either to a single hypothesis or to both hypotheses. We fitted mixed-effects models and used the Akaike information criterion and the Bayesian information criterion values to compare the competing models of the value of the obtained evidence. Overall, the experiments showed that measure Z was the best fitting model of participants' judgments of the value of obtained answers. We discussed the implications for the human hypothesis-evaluation process. PMID:24446753
Optimization of digital designs
NASA Technical Reports Server (NTRS)
Whitaker, Sterling R. (Inventor); Miles, Lowell H. (Inventor)
2009-01-01
An application specific integrated circuit is optimized by translating a first representation of its digital design to a second representation. The second representation includes multiple syntactic expressions that admit a representation of a higher-order function of base Boolean values. The syntactic expressions are manipulated to form a third representation of the digital design.
Bari, Md Niamul; Alam, Md Zahangir; Muyibi, Suleyman A; Jamal, Parveen; Abdullah-Al-Mamun
2009-06-01
A sequential optimization based on statistical design and one-factor-at-a-time (OFAT) method was employed to optimize the media constituents for the improvement of citric acid production from oil palm empty fruit bunches (EFB) through solid state bioconversion using Aspergillus niger IBO-103MNB. The results obtained from the Plackett-Burman design indicated that the co-substrate (sucrose), stimulator (methanol) and minerals (Zn, Cu, Mn and Mg) were found to be the major factors for further optimization. Based on the OFAT method, the selected medium constituents and inoculum concentration were optimized by the central composite design (CCD) under the response surface methodology (RSM). The statistical analysis showed that the optimum media containing 6.4% (w/w) of sucrose, 9% (v/w) of minerals and 15.5% (v/w) of inoculum gave the maximum production of citric acid (337.94 g/kg of dry EFB). The analysis showed that sucrose (p<0.0011) and mineral solution (p<0.0061) were more significant compared to inoculum concentration (p<0.0127) for the citric acid production. PMID:19231166
Gonnissen, J.; De Backer, A.; Martinez, G. T.; Van Aert, S.; Dekker, A. J. den; Rosenauer, A.; Sijbers, J.
2014-08-11
We report an innovative method to explore the optimal experimental settings to detect light atoms from scanning transmission electron microscopy (STEM) images. Since light elements play a key role in many technologically important materials, such as lithium-battery devices or hydrogen storage applications, much effort has been made to optimize the STEM technique in order to detect light elements. Therefore, classical performance criteria, such as contrast or signal-to-noise ratio, are often discussed hereby aiming at improvements of the direct visual interpretability. However, when images are interpreted quantitatively, one needs an alternative criterion, which we derive based on statistical detection theory. Using realistic simulations of technologically important materials, we demonstrate the benefits of the proposed method and compare the results with existing approaches.
NASA Technical Reports Server (NTRS)
Johannsen, G.; Govindaraj, T.
1980-01-01
The influence of different types of predictor displays in a longitudinal vertical takeoff and landing (VTOL) hover task is analyzed in a theoretical study. Several cases with differing amounts of predictive and rate information are compared. The optimal control model of the human operator is used to estimate human and system performance in terms of root-mean-square (rms) values and to compute optimized attention allocation. The only part of the model which is varied to predict these data is the observation matrix. Typical cases are selected for a subsequent experimental validation. The rms values as well as eye-movement data are recorded. The results agree favorably with those of the theoretical study in terms of relative differences. Better matching is achieved by revised model input data.
Optimal designs for copula models
Perrone, E.; Müller, W.G.
2016-01-01
Copula modelling has in the past decade become a standard tool in many areas of applied statistics. However, a largely neglected aspect concerns the design of related experiments. Particularly the issue of whether the estimation of copula parameters can be enhanced by optimizing experimental conditions and how robust all the parameter estimates for the model are with respect to the type of copula employed. In this paper an equivalence theorem for (bivariate) copula models is provided that allows formulation of efficient design algorithms and quick checks of whether designs are optimal or at least efficient. Some examples illustrate that in practical situations considerable gains in design efficiency can be achieved. A natural comparison between different copula models with respect to design efficiency is provided as well. PMID:27453616
El-Malah, Yasser; Nazzal, Sami
2013-01-01
The objective of this work was to study the dissolution and mechanical properties of fast-dissolving films prepared from a tertiary mixture of pullulan, polyvinylpyrrolidone and hypromellose. Disintegration studies were performed in real-time by probe spectroscopy to detect the onset of film disintegration. Tensile strength and elastic modulus of the films were measured by texture analysis. Disintegration time of the films ranged from 21 to 105 seconds whereas their mechanical properties ranged from approximately 2 to 49 MPa for tensile strength and 1 to 21 MPa% for young's modulus. After generating polynomial models correlating the variables using a D-Optimal mixture design, an optimal formulation with desired responses was proposed by the statistical package. For validation, a new film formulation loaded with diclofenac sodium based on the optimized composition was prepared and tested for dissolution and tensile strength. Dissolution of the optimized film was found to commence almost immediately with 50% of the drug released within one minute. Tensile strength and young's modulus of the film were 11.21 MPa and 6, 78 MPa%, respectively. Real-time spectroscopy in conjunction with statistical design were shown to be very efficient for the optimization and development of non-conventional intraoral delivery system such as fast dissolving films. PMID:22780708
Chen, Zhen-Min; Li, Qing; Liu, Hua-Mei; Yu, Na; Xie, Tian-Jian; Yang, Ming-Yuan; Shen, Ping; Chen, Xiang-Dong
2010-02-01
Bacillus subtilis spore preparations are promising probiotics and biocontrol agents, which can be used in plants, animals, and humans. The aim of this work was to optimize the nutritional conditions using a statistical approach for the production of B. subtilis (WHK-Z12) spores. Our preliminary experiments show that corn starch, corn flour, and wheat bran were the best carbon sources. Using Plackett-Burman design, corn steep liquor, soybean flour, and yeast extract were found to be the best nitrogen source ingredients for enhancing spore production and were studied for further optimization using central composite design. The key medium components in our optimization medium were 16.18 g/l of corn steep liquor, 17.53 g/l of soybean flour, and 8.14 g/l of yeast extract. The improved medium produced spores as high as 1.52 +/- 0.06 x 10(10) spores/ml under flask cultivation conditions, and 1.56 +/- 0.07 x 10(10) spores/ml could be achieved in a 30-l fermenter after 40 h of cultivation. To the best of our knowledge, these results compared favorably to the documented spore yields produced by B. subtilis strains. PMID:19697022
Tebani, Abdellah; Schmitz-Afonso, Isabelle; Rutledge, Douglas N; Gonzalez, Bruno J; Bekri, Soumeya; Afonso, Carlos
2016-03-24
High-resolution mass spectrometry coupled with pattern recognition techniques is an established tool to perform comprehensive metabolite profiling of biological datasets. This paves the way for new, powerful and innovative diagnostic approaches in the post-genomic era and molecular medicine. However, interpreting untargeted metabolomic data requires robust, reproducible and reliable analytical methods to translate results into biologically relevant and actionable knowledge. The analyses of biological samples were developed based on ultra-high performance liquid chromatography (UHPLC) coupled to ion mobility - mass spectrometry (IM-MS). A strategy for optimizing the analytical conditions for untargeted UHPLC-IM-MS methods is proposed using an experimental design approach. Optimization experiments were conducted through a screening process designed to identify the factors that have significant effects on the selected responses (total number of peaks and number of reliable peaks). For this purpose, full and fractional factorial designs were used while partial least squares regression was used for experimental design modeling and optimization of parameter values. The total number of peaks yielded the best predictive model and is used for optimization of parameters setting. PMID:26944989
Lorenz, Romy; Monti, Ricardo Pio; Violante, Inês R.; Anagnostopoulos, Christoforos; Faisal, Aldo A.; Montana, Giovanni; Leech, Robert
2016-01-01
Functional neuroimaging typically explores how a particular task activates a set of brain regions. Importantly though, the same neural system can be activated by inherently different tasks. To date, there is no approach available that systematically explores whether and how distinct tasks probe the same neural system. Here, we propose and validate an alternative framework, the Automatic Neuroscientist, which turns the standard fMRI approach on its head. We use real-time fMRI in combination with modern machine-learning techniques to automatically design the optimal experiment to evoke a desired target brain state. In this work, we present two proof-of-principle studies involving perceptual stimuli. In both studies optimization algorithms of varying complexity were employed; the first involved a stochastic approximation method while the second incorporated a more sophisticated Bayesian optimization technique. In the first study, we achieved convergence for the hypothesized optimum in 11 out of 14 runs in less than 10 min. Results of the second study showed how our closed-loop framework accurately and with high efficiency estimated the underlying relationship between stimuli and neural responses for each subject in one to two runs: with each run lasting 6.3 min. Moreover, we demonstrate that using only the first run produced a reliable solution at a group-level. Supporting simulation analyses provided evidence on the robustness of the Bayesian optimization approach for scenarios with low contrast-to-noise ratio. This framework is generalizable to numerous applications, ranging from optimizing stimuli in neuroimaging pilot studies to tailoring clinical rehabilitation therapy to patients and can be used with multiple imaging modalities in humans and animals. PMID:26804778
Lorenz, Romy; Monti, Ricardo Pio; Violante, Inês R; Anagnostopoulos, Christoforos; Faisal, Aldo A; Montana, Giovanni; Leech, Robert
2016-04-01
Functional neuroimaging typically explores how a particular task activates a set of brain regions. Importantly though, the same neural system can be activated by inherently different tasks. To date, there is no approach available that systematically explores whether and how distinct tasks probe the same neural system. Here, we propose and validate an alternative framework, the Automatic Neuroscientist, which turns the standard fMRI approach on its head. We use real-time fMRI in combination with modern machine-learning techniques to automatically design the optimal experiment to evoke a desired target brain state. In this work, we present two proof-of-principle studies involving perceptual stimuli. In both studies optimization algorithms of varying complexity were employed; the first involved a stochastic approximation method while the second incorporated a more sophisticated Bayesian optimization technique. In the first study, we achieved convergence for the hypothesized optimum in 11 out of 14 runs in less than 10min. Results of the second study showed how our closed-loop framework accurately and with high efficiency estimated the underlying relationship between stimuli and neural responses for each subject in one to two runs: with each run lasting 6.3min. Moreover, we demonstrate that using only the first run produced a reliable solution at a group-level. Supporting simulation analyses provided evidence on the robustness of the Bayesian optimization approach for scenarios with low contrast-to-noise ratio. This framework is generalizable to numerous applications, ranging from optimizing stimuli in neuroimaging pilot studies to tailoring clinical rehabilitation therapy to patients and can be used with multiple imaging modalities in humans and animals. PMID:26804778
Oberoi, Harinder Singh; Vadlani, Praveen Venkata; Madl, Ronald L; Saida, Lavudi; Abeykoon, Jithma P
2010-03-24
Orange peels were evaluated as a fermentation feedstock, and process conditions for enhanced ethanol production were determined. Primary hydrolysis of orange peel powder (OPP) was carried out at acid concentrations from 0 to 1.0% (w/v) at 121 degrees C and 15 psi for 15 min. High-performance liquid chromatography analysis of sugars and inhibitory compounds showed a higher production of hydroxymethyfurfural and acetic acid and a decrease in sugar concentration when the acid level was beyond 0.5% (w/v). Secondary hydrolysis of pretreated biomass obtained from primary hydrolysis was carried out at 0.5% (w/v) acid. Response surface methodology using three factors and a two-level central composite design was employed to optimize the effect of pH, temperature, and fermentation time on ethanol production from OPP hydrolysate at the shake flask level. On the basis of results obtained from the optimization experiment and numerical optimization software, a validation study was carried out in a 2 L batch fermenter at pH 5.4 and a temperature of 34 degrees C for 15 h. The hydrolysate obtained from primary and secondary hydrolysis processes was fermented separately employing parameters optimized through RSM. Ethanol yields of 0.25 g/g on a biomass basis (YP/X) and 0.46 g/g on a substrate-consumed basis (YP/S) and a promising volumetric ethanol productivity of 3.37 g/L/h were attained using this process at the fermenter level, which shows promise for further scale-up studies. PMID:20158208
NASA Astrophysics Data System (ADS)
Singh, Balbir; Radhakrishnan, Jayakrishnan
The need for uniform stress distribution of early super pressure balloons led a long period of the development of several optimal designs of scientific balloons for significant benefits in public outreach and education for the next generation of scientists, engineers and technicians. Scientific ballooning is continuing to evolve. The paper is divided into two sections. First section deals with the design, development and optimization of a cost effective high altitude ultra-long duration scientific balloon which are made up of stiff meridional tendons of a specific material. The numerical calculation along with the analysis of elastic buckling pressure, anisotropic viscoelstic effects is taken into consideration. The second section deals with the stability of the ULD balloon constructed by joining together a number of gores so that the structure forms a series of bulges and lobes. Under certain condition at high altitudes the nominal configuration of these structures is unstable and hence the analysis for development scenario must be envisaged so that the structure will never assume its intended shape which may end up in distorted but more stable configuration. The stability of the structure is shown depending upon the geometry and calculations using different softwares like MATLAB 2012b, ANSYS 14.0 (APDL).
Yang, S. M.; Hsieh, Y. C.; Jeng, C. A.
2009-03-15
Conventional antireflection coating by thin films of quarter-wavelength thickness is limited by material selections and these films' refractive indices. The optimal design by non-quarter-wavelength thickness is presented in this study. A multilayer thin-film model is developed by the admittance loci to show that the two-layer thin film of SiN{sub x}/SiO{sub y} at 124/87 nm and three layer of SiN{sub x}/SiN{sub y}/SiO{sub z} at 58/84/83 nm can achieve average transmittances of 94.4% and 94.9%, respectively, on polymer, glass, and silicon substrates. The optimal design is validated by plasma enhanced chemical vapor deposition of N{sub 2}O/SiH{sub 4} and NH{sub 3}/SiH{sub 4} to achieve the desired optical constants. Application of the antireflection coating to a 4 in. liquid crystal display demonstrates that the transmittance is over 94%, the mean luminance can be increased by 25%, and the total reflection angle increased from 41 deg. to 58 deg.
Fernández, P; Taboada, V; Regenjo, M; Morales, L; Alvarez, I; Carro, A M; Lorenzo, R A
2016-05-30
A simple Ultrasounds Assisted-Dispersive Liquid Liquid Microextraction (UA-DLLME) method is presented for the simultaneous determination of six second-generation antidepressants in plasma by Ultra Performance Liquid Chromatography with Photodiode Array Detector (UPLC-PDA). The main factors that potentially affect to DLLME were optimized by a screening design followed by a response surface design and desirability functions. The optimal conditions were 2.5mL of acetonitrile as dispersant solvent, 0.2mL of chloroform as extractant solvent, 3min of ultrasounds stirring and extraction pH 9.8.Under optimized conditions, the UPLC-PDA method showed good separation of antidepressants in 2.5min and good linearity in the range of 0.02-4μgmL(-1), with determination coefficients higher than 0.998. The limits of detection were in the range 4-5ngmL(-1). The method precision (n=5) was evaluated showing relative standard deviations (RSD) lower than 8.1% for all compounds. The average recoveries ranged from 92.5% for fluoxetine to 110% for mirtazapine. The applicability of DLLME/UPLC-PDA was successfully tested in twenty nine plasma samples from antidepressant consumers. Real samples were analyzed by the proposed method and the results were successfully submitted to comparison with those obtained by a Liquid Liquid Extraction-Gas Chromatography - Mass Spectrometry (LLE-GC-MS) method. The results confirmed the presence of venlafaxine in most cases (19 cases), followed by sertraline (3 cases) and fluoxetine (3 cases) at concentrations below toxic levels. PMID:26955756
Elements of Bayesian experimental design
Sivia, D.S.
1997-09-01
We consider some elements of the Bayesian approach that are important for optimal experimental design. While the underlying principles used are very general, and are explained in detail in a recent tutorial text, they are applied here to the specific case of characterising the inferential value of different resolution peakshapes. This particular issue was considered earlier by Silver, Sivia and Pynn (1989, 1990a, 1990b), and the following presentation confirms and extends the conclusions of their analysis.
NASA Astrophysics Data System (ADS)
Gao, Xinlu; Huang, Shanguo; Wei, Yongfeng; Zhai, Wensheng; Xu, Wenjing; Yin, Shan; Zhou, Jing; Gu, Wanyi
2014-12-01
A system of generating and receiving orbital angular momentum (OAM) radio beams, which are collectively formed by two circular array antennas (CAAs) and effectively optimized by two intensity controlled masks, is proposed and experimentally investigated. The scheme is effective in blocking of the unwanted OAM modes and enhancing the power of received radio signals, which results in the capacity gain of system and extended transmission distance of the OAM radio beams. The operation principle of the intensity controlled masks, which can be regarded as both collimator and filter, is feasible and simple to realize. Numerical simulations of intensity and phase distributions at each key cross-sectional plane of the radio beams demonstrate the collimated results. The experimental results match well with the theoretical analysis and the receive distance of the OAM radio beam at radio frequency (RF) 20 GHz is extended up to 200 times of the wavelength of the RF signals, the measured distance is 5 times of the original measured distance. The presented proof-of-concept experiment demonstrates the feasibility of the system.
Gao, Xinlu; Huang, Shanguo Wei, Yongfeng; Zhai, Wensheng; Xu, Wenjing; Yin, Shan; Gu, Wanyi; Zhou, Jing
2014-12-15
A system of generating and receiving orbital angular momentum (OAM) radio beams, which are collectively formed by two circular array antennas (CAAs) and effectively optimized by two intensity controlled masks, is proposed and experimentally investigated. The scheme is effective in blocking of the unwanted OAM modes and enhancing the power of received radio signals, which results in the capacity gain of system and extended transmission distance of the OAM radio beams. The operation principle of the intensity controlled masks, which can be regarded as both collimator and filter, is feasible and simple to realize. Numerical simulations of intensity and phase distributions at each key cross-sectional plane of the radio beams demonstrate the collimated results. The experimental results match well with the theoretical analysis and the receive distance of the OAM radio beam at radio frequency (RF) 20 GHz is extended up to 200 times of the wavelength of the RF signals, the measured distance is 5 times of the original measured distance. The presented proof-of-concept experiment demonstrates the feasibility of the system.
NASA Astrophysics Data System (ADS)
Karaagac, Oznur; Kockar, Hakan
2016-07-01
Orthogonal design technique was applied to obtain superparamagnetic iron oxide nanoparticles with high saturation magnetization, Ms. Synthesis of the nanoparticles were done in air atmosphere according to the orthogonal table L934. Magnetic properties of the synthesized nanoparticles were measured by a vibrating sample magnetometer. Structural analysis of the nanoparticles was also carried out by X-ray diffraction technique (XRD), Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). After the analysis of magnetic data, the optimized experimental parameters were determined as [Fe+2]/[Fe+3]=6/6, iron ion concentration=1500 mM, base concentration=6.7 M and reaction time=2 min. Magnetic results showed that the synthesis carried out according to the optimized conditions gave the highest Ms of 69.83 emu/g for the nanoparticles synthesized in air atmosphere. Magnetic measurements at 10 K and 300 K showed the sample is superparamagnetic at room temperature. Structural analysis by XRD, FTIR and selected area electron diffraction showed that the sample had the inverse spinel crystal structure of iron oxide. The particle size of the optimized sample determined from the TEM image is 7.0±2.2 nm. The results indicated that the Ms of superparamagnetic iron oxide nanoparticles can be optimized by experimental design with the suitable choice of the synthesis parameters.
Fry, Derek J
2014-01-01
Awareness of poor design and published concerns over study quality stimulated the development of courses on experimental design intended to improve matters. This article describes some of the thinking behind these courses and how the topics can be presented in a variety of formats. The premises are that education in experimental design should be undertaken with an awareness of educational principles, of how adults learn, and of the particular topics in the subject that need emphasis. For those using laboratory animals, it should include ethical considerations, particularly severity issues, and accommodate learners not confident with mathematics. Basic principles, explanation of fully randomized, randomized block, and factorial designs, and discussion of how to size an experiment form the minimum set of topics. A problem-solving approach can help develop the skills of deciding what are correct experimental units and suitable controls in different experimental scenarios, identifying when an experiment has not been properly randomized or blinded, and selecting the most efficient design for particular experimental situations. Content, pace, and presentation should suit the audience and time available, and variety both within a presentation and in ways of interacting with those being taught is likely to be effective. Details are given of a three-day course based on these ideas, which has been rated informative, educational, and enjoyable, and can form a postgraduate module. It has oral presentations reinforced by group exercises and discussions based on realistic problems, and computer exercises which include some analysis. Other case studies consider a half-day format and a module for animal technicians. PMID:25541547
NASA Astrophysics Data System (ADS)
Nguyen, Gia Luong Huu
obtained experimental data, the research studied the control of airflow to regulate the temperature of reactors within the fuel processor. The dynamic model provided a platform to test the dynamic response for different control gains. With sufficient sensing and appropriate control, a rapid response to maintain the temperature of the reactor despite an increase in power was possible. The third part of the research studied the use of a fuel cell in conjunction with photovoltaic panels, and energy storage to provide electricity for buildings. This research developed an optimization framework to determine the size of each device in the hybrid energy system to satisfy the electrical demands of buildings and yield the lowest cost. The advantage of having the fuel cell with photovoltaic and energy storage was the ability to operate the fuel cell at baseload at night, thus reducing the need for large battery systems to shift the solar power produced in the day to the night. In addition, the dispatchability of the fuel cell provided an extra degree of freedom necessary for unforeseen disturbances. An operation framework based on model predictive control showed that the method is suitable for optimizing the dispatch of the hybrid energy system.
Hassan, W.; Vensel, F.; Knowles, B.
2006-03-06
The inspection of critical rotating components of aircraft engines has made important advances over the last decade. The development of Phased Array (PA) inspection capability for billet and forging materials used in the manufacturing of critical engine rotating components has been a priority for Honeywell Aerospace. The demonstration of improved PA inspection system sensitivity over what is currently used at the inspection houses is a critical step in the development of this technology and its introduction to the supply base as a production inspection. As described in Part I (in these proceedings), a new phased array transducer was designed and manufactured for optimal inspection of eight inch diameter Ti-6Al-4V billets. After confirming that the transducer was manufactured in accordance with the design specifications a validation study was conducted to assess the sensitivity improvement of the PAI over the current capability of Multi-zone (MZ) inspection. The results of this study confirm the significant ({approx_equal} 6 dB in FBH number sign sensitivity) improvement of the PAI sensitivity over that of MZI.
Optimized quadrature surface coil designs
Kumar, Ananda; Bottomley, Paul A.
2008-01-01
Background Quadrature surface MRI/MRS detectors comprised of circular loop and figure-8 or butterfly-shaped coils offer improved signal-to-noise-ratios (SNR) compared to single surface coils, and reduced power and specific absorption rates (SAR) when used for MRI excitation. While the radius of the optimum loop coil for performing MRI at depth d in a sample is known, the optimum geometry for figure-8 and butterfly coils is not. Materials and methods The geometries of figure-8 and square butterfly detector coils that deliver the optimum SNR are determined numerically by the electromagnetic method of moments. Figure-8 and loop detectors are then combined to create SNR-optimized quadrature detectors whose theoretical and experimental SNR performance are compared with a novel quadrature detector comprised of a strip and a loop, and with two overlapped loops optimized for the same depth at 3 T. The quadrature detection efficiency and local SAR during transmission for the three quadrature configurations are analyzed and compared. Results The SNR-optimized figure-8 detector has loop radius r8 ∼ 0.6d, so r8/r0 ∼ 1.3 in an optimized quadrature detector at 3 T. The optimized butterfly coil has side length ∼ d and crossover angle of ≥ 150° at the center. Conclusions These new design rules for figure-8 and butterfly coils optimize their performance as linear and quadrature detectors. PMID:18057975
Torres, Ricardo A; Mosteo, Rosa; Pétrier, Christian; Pulgarin, Cesar
2009-03-01
This work presents the application of experimental design for the ultrasonic degradation of alachlor which is pesticide classified as priority substance by the European Commission within the scope of the Water Framework Directive. The effect of electrical power (20-80W), pH (3-10) and substrate concentration (10-50mgL(-1)) was evaluated. For a confidential level of 90%, pH showed a low effect on the initial degradation rate of alachlor; whereas electrical power, pollutant concentration and the interaction of these two parameters were significant. A reduced model taking into account the significant variables and interactions between variables has shown a good correlation with the experimental results. Additional experiments conducted in natural and deionised water indicated that the alachlor degradation by ultrasound is practically unaffected by the presence of potential *OH radical scavengers: bicarbonate, sulphate, chloride and oxalic acid. In both cases, alachlor was readily eliminated ( approximately 75min). However, after 4h of treatment only 20% of the initial TOC was removed, showing that alachlor by-products are recalcitrant to the ultrasonic action. Biodegradability test (BOD5/COD) carried out during the course of the treatment indicated that the ultrasonic system noticeably increases the biodegradability of the initial solution. PMID:18930694
OPTIMAL NETWORK TOPOLOGY DESIGN
NASA Technical Reports Server (NTRS)
Yuen, J. H.
1994-01-01
This program was developed as part of a research study on the topology design and performance analysis for the Space Station Information System (SSIS) network. It uses an efficient algorithm to generate candidate network designs (consisting of subsets of the set of all network components) in increasing order of their total costs, and checks each design to see if it forms an acceptable network. This technique gives the true cost-optimal network, and is particularly useful when the network has many constraints and not too many components. It is intended that this new design technique consider all important performance measures explicitly and take into account the constraints due to various technical feasibilities. In the current program, technical constraints are taken care of by the user properly forming the starting set of candidate components (e.g. nonfeasible links are not included). As subsets are generated, they are tested to see if they form an acceptable network by checking that all requirements are satisfied. Thus the first acceptable subset encountered gives the cost-optimal topology satisfying all given constraints. The user must sort the set of "feasible" link elements in increasing order of their costs. The program prompts the user for the following information for each link: 1) cost, 2) connectivity (number of stations connected by the link), and 3) the stations connected by that link. Unless instructed to stop, the program generates all possible acceptable networks in increasing order of their total costs. The program is written only to generate topologies that are simply connected. Tests on reliability, delay, and other performance measures are discussed in the documentation, but have not been incorporated into the program. This program is written in PASCAL for interactive execution and has been implemented on an IBM PC series computer operating under PC DOS. The disk contains source code only. This program was developed in 1985.
De Beer, T R M; Wiggenhorn, M; Hawe, A; Kasper, J C; Almeida, A; Quinten, T; Friess, W; Winter, G; Vervaet, C; Remon, J P
2011-02-15
The aim of the present study was to examine the possibilities/advantages of using recently introduced in-line spectroscopic process analyzers (Raman, NIR and plasma emission spectroscopy), within well-designed experiments, for the optimization of a pharmaceutical formulation and its freeze-drying process. The formulation under investigation was a mannitol (crystalline bulking agent)-sucrose (lyo- and cryoprotector) excipient system. The effects of two formulation variables (mannitol/sucrose ratio and amount of NaCl) and three process variables (freezing rate, annealing temperature and secondary drying temperature) upon several critical process and product responses (onset and duration of ice crystallization, onset and duration of mannitol crystallization, duration of primary drying, residual moisture content and amount of mannitol hemi-hydrate in end product) were examined using a design of experiments (DOE) methodology. A 2-level fractional factorial design (2(5-1)=16 experiments+3 center points=19 experiments) was employed. All experiments were monitored in-line using Raman, NIR and plasma emission spectroscopy, which supply continuous process and product information during freeze-drying. Off-line X-ray powder diffraction analysis and Karl-Fisher titration were performed to determine the morphology and residual moisture content of the end product, respectively. In first instance, the results showed that - besides the previous described findings in De Beer et al., Anal. Chem. 81 (2009) 7639-7649 - Raman and NIR spectroscopy are able to monitor the product behavior throughout the complete annealing step during freeze-drying. The DOE approach allowed predicting the optimum combination of process and formulation parameters leading to the desired responses. Applying a mannitol/sucrose ratio of 4, without adding NaCl and processing the formulation without an annealing step, using a freezing rate of 0.9°C/min and a secondary drying temperature of 40°C resulted in
Khan, M Nisa
2015-07-20
Light-emitting diode (LED) technologies are undergoing very fast developments to enable household lamp products with improved energy efficiency and lighting properties at lower cost. Although many LED replacement lamps are claimed to provide similar or better lighting quality at lower electrical wattage compared with general-purpose incumbent lamps, certain lighting characteristics important to human vision are neglected in this comparison, which include glare-free illumination and omnidirectional or sufficiently broad light distribution with adequate homogeneity. In this paper, we comprehensively investigate the thermal and lighting performance and trade-offs for several commercial LED replacement lamps for the most popular Edison incandescent bulb. We present simulations and analyses for thermal and optical performance trade-offs for various LED lamps at the chip and module granularity levels. In addition, we present a novel, glare-free, and production-friendly LED lamp design optimized to produce very desirable light distribution properties as demonstrated by our simulation results, some of which are verified by experiments. PMID:26367844
NASA Astrophysics Data System (ADS)
Rettig, Ralf; Ritter, Nils C.; Helmer, Harald E.; Neumeier, Steffen; Singer, Robert F.
2015-04-01
A method for finding the optimum alloy compositions considering a large number of property requirements and constraints by systematic exploration of large composition spaces is proposed. It is based on a numerical multi-criteria global optimization algorithm (multistart solver using Sequential Quadratic Programming), which delivers the exact optimum considering all constraints. The CALPHAD method is used to provide the thermodynamic equilibrium properties, and the creep strength of the alloys is predicted based on a qualitative numerical model considering the solid solution strengthening of the matrix by the elements Re, Mo and W and the optimum morphology and fraction of the γ‧-phase. The calculated alloy properties which are required as an input for the optimization algorithm are provided via very fast Kriging surrogate models. This greatly reduces the total calculation time of the optimization to the order of minutes on a personal computer. The capability of the multi-criteria optimization method developed was experimentally verified with two new single crystal superalloys. Their compositions were designed such that the content of expensive elements was reduced. One of the newly designed alloys, termed ERBO/13, is found to possess creep strength of only 14 K below CMSX-4 in the high-temperature/low-stress regime although it is a Re-free alloy.
Rodríguez de San Miguel, Eduardo; Vital, Xóchitl; de Gyves, Josefina
2014-05-30
Chromium(VI) transport through a supported liquid membrane (SLM) system containing the commercial ionic liquid CYPHOS IL101 as carrier was studied. A reducing stripping phase was used as a mean to increase recovery and to simultaneously transform Cr(VI) into a less toxic residue for disposal or reuse. General functions which describe the time-depending evolution of the metal fractions in the cell compartments were defined and used in data evaluation. An experimental design strategy, using factorial and central-composite design matrices, was applied to assess the influence of the extractant, NaOH and citrate concentrations in the different phases, while a desirability function scheme allowed the synchronized optimization of depletion and recovery of the analyte. The mechanism for chromium permeation was analyzed and discussed to contribute to the understanding of the transfer process. The influence of metal concentration was evaluated as well. The presence of different interfering ions (Ca(2+), Al(3+), NO3(-), SO4(2-), and Cl(-)) at several Cr(VI): interfering ion ratios was studied through the use of a Plackett and Burman experimental design matrix. Under optimized conditions 90% of recovery was obtained from a feed solution containing 7mgL(-1) of Cr(VI) in 0.01moldm(-3) HCl medium after 5h of pertraction. PMID:24751491
Kindossi, Janvier Mêlégnonfan; Anihouvi, Victor Bienvenu; Vieira-Dalodé, Générose; Akissoé, Noël Houédougbé; Hounhouigan, Djidjoho Joseph
2016-03-01
Lanhouin is a traditional fermented salted fish made from the spontaneous and uncontrolled fermentation of whole salted cassava fish (Pseudotolithus senegalensis) mainly produced in the coastal regions of West Africa. The combined effects of NaCl, citric acid concentration, and marination time on the physicochemical and microbiological characteristics of the fish fillet used for Lanhouin production were studied using a Doehlert experimental design with the objective of preserving its quality and safety. The marination time has significant effects on total viable and lactic acid bacteria counts, and NaCl content of the marinated fish fillet while the pH was significantly affected by citric acid concentration and marination duration with high regression coefficient R (2) of 0.83. The experiment showed that the best conditions for marination process of fish fillet were salt ratio 10 g/100 g, acid citric concentration 2.5 g/100 g, and marination time 6 h. These optimum marinating conditions obtained present the best quality of marinated flesh fish leading to the safety of the final fermented product. This pretreatment is necessary in Lanhouin production processes to ensure its safety quality. PMID:27004115
Demiralay, Ebru Çubuk
2012-06-01
An optimization methodology is introduced for investigating the retention behavior and the separation factor of metformin, gliclazide (I.S.) and glibenclamide. This investigation has been focused on studying the influence of pH value of the mobile phase, concentration of acetonitrile and column temperature, which affect a complete separation of the chromatographic peaks of these compounds. The significant factors were optimized using full factorial design. Retention factor and separation factor were chosen as dependent variable. Optimum RP-LC chromatographic conditions for the separation of metformin, glibenclamide and gliclazide were obtained using X Terra column (150 mm × 4.6 mm I.D., 5 µm). The results show that the percentage of acetonitrile are the most important to investigate and sspH of the mobile phase and column temperature do not significantly affect the experimental results. The procedure was validated for linearity, accuracy, precision and recovery. Quantitation was accomplished using internal standard method. PMID:24061246
Aerodynamic design using numerical optimization
NASA Technical Reports Server (NTRS)
Murman, E. M.; Chapman, G. T.
1983-01-01
The procedure of using numerical optimization methods coupled with computational fluid dynamic (CFD) codes for the development of an aerodynamic design is examined. Several approaches that replace wind tunnel tests, develop pressure distributions and derive designs, or fulfill preset design criteria are presented. The method of Aerodynamic Design by Numerical Optimization (ADNO) is described and illustrated with examples.
Structural Optimization in automotive design
NASA Technical Reports Server (NTRS)
Bennett, J. A.; Botkin, M. E.
1984-01-01
Although mathematical structural optimization has been an active research area for twenty years, there has been relatively little penetration into the design process. Experience indicates that often this is due to the traditional layout-analysis design process. In many cases, optimization efforts have been outgrowths of analysis groups which are themselves appendages to the traditional design process. As a result, optimization is often introduced into the design process too late to have a significant effect because many potential design variables have already been fixed. A series of examples are given to indicate how structural optimization has been effectively integrated into the design process.
NASA Astrophysics Data System (ADS)
Roosta, M.; Ghaedi, M.; Shokri, N.; Daneshfar, A.; Sahraei, R.; Asghari, A.
2014-01-01
The present study was aimed to experimental design optimization applied to removal of malachite green (MG) from aqueous solution by ultrasound-assisted removal onto the gold nanoparticles loaded on activated carbon (Au-NP-AC). This nanomaterial was characterized using different techniques such as FESEM, TEM, BET, and UV-vis measurements. The effects of variables such as pH, initial dye concentration, adsorbent dosage (g), temperature and sonication time on MG removal were studied using central composite design (CCD) and the optimum experimental conditions were found with desirability function (DF) combined response surface methodology (RSM). Fitting the experimental equilibrium data to various isotherm models such as Langmuir, Freundlich, Tempkin and Dubinin-Radushkevich models show the suitability and applicability of the Langmuir model. Kinetic models such as pseudo -first order, pseudo-second order, Elovich and intraparticle diffusion models applicability was tested for experimental data and the second-order equation and intraparticle diffusion models control the kinetic of the adsorption process. The small amount of proposed adsorbent (0.015 g) is applicable for successful removal of MG (RE > 99%) in short time (4.4 min) with high adsorption capacity (140-172 mg g-1).
Colombo, Renata; Ferreira, Tanare C R; Ferreira, Renato A; Lanza, Marcos R V
2016-02-01
Mefenamic acid (MEF) is a non-steroidal anti-inflammatory drug indicated for relief of mild to moderate pain, and for the treatment of primary dysmenorrhea. The presence of MEF in raw and sewage waters has been detected worldwide at concentrations exceeding the predicted no-effect concentration. In this study, using experimental designs, different oxidative processes (H2O2, H2O2/UV, fenton and Photo-fenton) were simultaneously evaluated for MEF degradation efficiency. The influence and interaction effects of the most important variables in the oxidative process (concentration and addition mode of hydrogen peroxide, concentration and type of catalyst, pH, reaction period and presence/absence of light) were investigated. The parameters were determined based on the maximum efficiency to save time and minimize the consumption of reagents. According to the results, the photo-Fenton process is the best procedure to remove the drug from water. A reaction mixture containing 1.005 mmol L(-1) of ferrioxalate and 17.5 mmol L(-1) of hydrogen peroxide, added at the initial reaction period, pH of 6.1 and 60 min of degradation indicated the most efficient degradation, promoting 95% of MEF removal. The development and validation of a rapid and efficient qualitative and quantitative HPLC/UV methodology for detecting this pollutant in aqueous solution is also reported. The method can be applied in water quality control that is generated and/or treated in municipal or industrial wastewater treatment plants. PMID:26686073
L'Hocine, Lamia; Pitre, Mélanie
2016-03-01
A full factorial design was used to assess the single and interactive effects of three non-denaturing aqueous (phosphate, borate, and carbonate) buffers at various ionic strengths (I) on allergen extractability from and immunoglobulin E (IgE) immunoreactivity of peanut, almond, hazelnut, and pistachio. The results indicated that the type and ionic strength of the buffer had different effects on protein recovery from the nuts under study. Substantial differences in protein profiles, abundance, and IgE-binding intensity with different combinations of pH and ionic strength were found. A significant interaction between pH and ionic strength was observed for pistachio and almond. The optimal buffer system conditions, which maximized the IgE-binding efficiency of allergens and provided satisfactory to superior protein recovery yield and profiles, were carbonate buffer at an ionic strength of I=0.075 for peanut, carbonate buffer at I=0.15 for almond, phosphate buffer at I=0.5 for hazelnut, and borate at I=0.15 for pistachio. The buffer type and its ionic strength could be manipulated to achieve the selective solubility of desired allergens. PMID:26471623
Du, Xilin; Li, Yaqian; Zhou, Wanping; Zhou, Quan; Liu, Haiming; Xu, Yuquan
2013-09-01
We constructed a non-scar triple-deleted mutant Pseudomonas aeruginosa to improve phenazine-1-carboxylic acid (PCA) yield and then optimized the culture conditions for PCA production. Using a non-scar deletion strategy, the 5'-untranslated region of the phz1 gene cluster and two genes, phzM and phzS, were knocked out of the P. aeruginosa strain M18 genome. The potential ability for high-yield PCA production in this triple-deleted mutant M18MSU1 was successfully realized by using statistical experimental designs. A 2(5-1) fractional factorial design was used to show that the three culture components of soybean meal, corn steep liquor and ethanol had the most significant effect on PCA production. Using a central composite design, the concentration of the three components was optimized. The maximum PCA production was predicted to be 4,725.1 mg/L. With the optimal medium containing soybean meal 74.25 g/L, corn steep liquor 13.01 g/L and ethanol 21.84 ml/L, a PCA production of 4,771.2 mg/L was obtained in the validation experiments, which was nearly twofold of that before optimization and tenfold of that in the wild-type strain. This non-scar triple-deleted mutant M18MSU1 may be a suitable strain for industrial production of this biologically synthesized fungicide due to its high PCA production, presumed safety, thermal adaptability and cost-effectiveness. PMID:23636695
Propeller design by numerical optimization
NASA Technical Reports Server (NTRS)
Mendoza, J. P.
1977-01-01
A computer program designed to optimize propeller characteristics was developed by combining two main programs: the first is the optimization program based on the gradient algorithm; the second is based on a propeller blade element theory and uses an aerodynamics subprogram to approximate the lift and drag characteristics of the NACA 16-series airfoil section. To evaluate the propeller program alone (with its aerodynamics subprogram), propeller characteristics were computed and compared to those from wind tunnel investigations conducted on three different NACA propellers. Although the thrust and power coefficients which were computed using the blade element theory were generally higher than the experimental results for two of the three propellers, the corresponding efficiencies showed good agreement for all three propellers. The propeller optimization program was then used to study the NACA 4-(5)(08)-03 propeller at various Mach numbers from 0.175 to 0.60. Improvements in propeller efficiency and thrust were obtained through the use of the propeller optimization program.
Integrated controls design optimization
Lou, Xinsheng; Neuschaefer, Carl H.
2015-09-01
A control system (207) for optimizing a chemical looping process of a power plant includes an optimizer (420), an income algorithm (230) and a cost algorithm (225) and a chemical looping process models. The process models are used to predict the process outputs from process input variables. Some of the process in puts and output variables are related to the income of the plant; and some others are related to the cost of the plant operations. The income algorithm (230) provides an income input to the optimizer (420) based on a plurality of input parameters (215) of the power plant. The cost algorithm (225) provides a cost input to the optimizer (420) based on a plurality of output parameters (220) of the power plant. The optimizer (420) determines an optimized operating parameter solution based on at least one of the income input and the cost input, and supplies the optimized operating parameter solution to the power plant.
Design Optimization Toolkit: Users' Manual
Aguilo Valentin, Miguel Alejandro
2014-07-01
The Design Optimization Toolkit (DOTk) is a stand-alone C++ software package intended to solve complex design optimization problems. DOTk software package provides a range of solution methods that are suited for gradient/nongradient-based optimization, large scale constrained optimization, and topology optimization. DOTk was design to have a flexible user interface to allow easy access to DOTk solution methods from external engineering software packages. This inherent flexibility makes DOTk barely intrusive to other engineering software packages. As part of this inherent flexibility, DOTk software package provides an easy-to-use MATLAB interface that enables users to call DOTk solution methods directly from the MATLAB command window.
Roush, W B; Boykin, D; Branton, S L
2004-08-01
A mixture experiment, a variant of response surface methodology, was designed to determine the proportion of time to feed broiler starter (23% protein), grower (20% protein), and finisher (18% protein) diets to optimize production and processing variables based on a total production time of 48 d. Mixture designs are useful for proportion problems where the components of the experiment (i.e., length of time the diets were fed) add up to a unity (48 d). The experiment was conducted with day-old male Ross x Ross broiler chicks. The birds were placed 50 birds per pen in each of 60 pens. The experimental design was a 10-point augmented simplex-centroid (ASC) design with 6 replicates of each point. Each design point represented the portion(s) of the 48 d that each of the diets was fed. Formulation of the diets was based on NRC standards. At 49 d, each pen of birds was evaluated for production data including BW, feed conversion, and cost of feed consumed. Then, 6 birds were randomly selected from each pen for processing data. Processing variables included live weight, hot carcass weight, dressing percentage, fat pad percentage, and breast yield (pectoralis major and pectoralis minor weights). Production and processing data were fit to simplex regression models. Model terms determined not to be significant (P > 0.05) were removed. The models were found to be statistically adequate for analysis of the response surfaces. A compromise solution was calculated based on optimal constraints designated for the production and processing data. The results indicated that broilers fed a starter and finisher diet for 30 and 18 d, respectively, would meet the production and processing constraints. Trace plots showed that the production and processing variables were not very sensitive to the grower diet. PMID:15339000
Rahmani, Anosheh; Selamat, Jinap; Soleimany, Farhang
2011-01-01
A reversed-phase HPLC optimization strategy is presented for investigating the separation and retention behavior of aflatoxin B1, B2, G1, G2, ochratoxin A and zearalenone, simultaneously. A fractional factorial design (FFD) was used to screen the significance effect of seven independent variables on chromatographic responses. The independent variables used were: (X1) column oven temperature (20-40°C), (X2) flow rate (0.8-1.2 ml/min), (X3) acid concentration in aqueous phase (0-2%), (X4) organic solvent percentage at the beginning (40-50%), and (X5) at the end (50-60%) of the gradient mobile phase, as well as (X6) ratio of methanol/acetonitrile at the beginning (1-4) and (X7) at the end (0-1) of gradient mobile phase. Responses of chromatographic analysis were resolution of mycotoxin peaks and HPLC run time. A central composite design (CCD) using response surface methodology (RSM) was then carried out for optimization of the most significant factors by multiple regression models for response variables. The proposed optimal method using 40°C oven temperature, 1 ml/min flow rate, 0.1% acetic acid concentration in aqueous phase, 41% organic phase (beginning), 60% organic phase (end), 1.92 ratio of methanol to acetonitrile (beginning) and 0.2 ratio (end) for X1-X7, respectively, showed good prediction ability between the experimental data and predictive values throughout the studied parameter space. Finally, the optimized method was validated by measuring the linearity, sensitivity, accuracy and precision parameters, and has been applied successfully to the analysis of spiked cereal samples. PMID:21598138
D-OPTIMAL EXPERIMENTAL DESIGNS TO TEST FOR DEPARTURE FROM ADDITIVITY IN A FIXED-RATIO RAY MIXTURE.
Risk assessors are becoming increasingly aware of the importance of assessing interactions between chemicals in a mixture. Most traditional designs for evaluating interactions are prohibitive when the number of chemicals in the mixture is large. However, evaluation of interacti...
NASA Technical Reports Server (NTRS)
Torres-Pomales, Wilfredo
2015-01-01
This report documents a case study on the application of Reliability Engineering techniques to achieve an optimal balance between performance and robustness by tuning the functional parameters of a complex non-linear control system. For complex systems with intricate and non-linear patterns of interaction between system components, analytical derivation of a mathematical model of system performance and robustness in terms of functional parameters may not be feasible or cost-effective. The demonstrated approach is simple, structured, effective, repeatable, and cost and time efficient. This general approach is suitable for a wide range of systems.
Jontschev, C; Welikowa, E
1981-01-01
Experiments have been performed to optimize the composition of tablets with 250 mg of noramidopyrine methanesulphonate sodium, 250 mg of aminophenazone and 100 mg of caffeine + sodium benzoate. The effects of the adjuvants Micricell, Aerosil 200, Kollidon CE 5050 and wheat starch on different tablet characteristics (disintegration, mechanical strength, friability and rheological properties) were studied. The results obtained permitted to prepare tablets with good properties: disintegration time, up to 194 s; mechanical strength, greater than 12 kg; friability, less than 0.250%. PMID:7220583
Experimental and Quasi-Experimental Design.
ERIC Educational Resources Information Center
Cottrell, Edward B.
With an emphasis on the problems of control of extraneous variables and threats to internal and external validity, the arrangement or design of experiments is discussed. The purpose of experimentation in an educational institution, and the principles governing true experimentation (randomization, replication, and control) are presented, as are…
NASA Astrophysics Data System (ADS)
Bigan, Muriel; Bigot, Julien; Mutel, Brigitte; Coqueret, Xavier
2008-02-01
This work deals with the chemical grafting of a styrene maleic anhydride copolymer on the surface of a previously hydrolyzed polyethylene terephthalate (PET) film 12 μm thick via covalent bond. Two different ways are studied. The first one involves an activation of the hydrolyzed PET by the triethylamine before the grafting step. In the second one, the copolymer reacts with the 4-dimethylaminopyridine in order to form maleinyl pyridinium salt which reacts with alcohol function of the hydrolyzed PET. Characterization and quantification of the grafting are performed by Fourier transform infrared spectroscopy. Factorial experiment designs are used to optimize the process and to estimate experimental parameters effects. The opportunity to associate the chemical process to a cold remote nitrogen plasma one is also examined.
Yiamsawas, Doungporn; Boonpavanitchakul, Kanittha; Kangwansupamonkon, Wiyong
2011-05-15
Research highlights: {yields} Taguchi robust design can be applied to study ZnO nanocrystal growth. {yields} Spherical-like and rod-like shaped of ZnO nanocrystals can be obtained from solvothermal method. {yields} [NaOH]/[Zn{sup 2+}] ratio plays the most important factor on the aspect ratio of prepared ZnO. -- Abstract: Zinc oxide (ZnO) nanoparticles and nanorods were successfully synthesized by a solvothermal process. Taguchi robust design was applied to study the factors which result in stronger ZnO nanocrystal growth. The factors which have been studied are molar concentration ratio of sodium hydroxide and zinc acetate, amount of polymer templates and molecular weight of polymer templates. Transmission electron microscopy and X-ray diffraction technique were used to analyze the experiment results. The results show that the concentration ratio of sodium hydroxide and zinc acetate ratio has the greatest effect on ZnO nanocrystal growth.
Sibanda, Wilbert; Pillay, Viness; Danckwerts, Michael P; Viljoen, Alvaro M; van Vuuren, Sandy; Khan, Riaz A
2004-03-12
A Plackett-Burman design was employed to develop and optimize a novel crosslinked calcium-aluminum-alginate-pectinate oilisphere complex as a potential system for the in vitro site-specific release of Mentha piperita, an essential oil used for the treatment of irritable bowel syndrome. The physicochemical and textural properties (dependent variables) of this complex were found to be highly sensitive to changes in the concentration of the polymers (0%-1.5% wt/vol), crosslinkers (0%-4% wt/vol), and crosslinking reaction times (0.5-6 hours) (independent variables). Particle size analysis indicated both unimodal and bimodal populations with the highest frequency of 2 mm oilispheres. Oil encapsulation ranged from 6 to 35 mg/100 mg oilispheres. Gravimetric changes of the crosslinked matrix indicated significant ion sequestration and loss in an exponential manner, while matrix erosion followed Higuchi's cube root law. Among the various measured responses, the total fracture energy was the most suitable optimization objective (R2 = 0.88, Durbin-Watson Index = 1.21%, Coefficient of Variation (CV) = 33.21%). The Lagrangian technique produced no significant differences (P > .05) between the experimental and predicted total fracture energy values (0.0150 vs 0.0107 J). Artificial Neural Networks, as an alternative predictive tool of the total fracture energy, was highly accurate (final mean square error of optimal network epoch approximately 0.02). Fused-coated optimized oilispheres produced a 4-hour lag phase followed by zero-order kinetics (n > 0.99), whereby analysis of release data indicated that diffusion (Fickian constant k1 = 0.74 vs relaxation constant k2 = 0.02) was the predominant release mechanism. PMID:15198539
Asfaram, Arash; Ghaedi, Mehrorang; Goudarzi, Alireza
2016-09-01
A simple, low cost and ultrasensitive method for the simultaneous preconcentration and determination of trace amount of auramine-O and malachite green in aqueous media following accumulation on novel and lower toxicity nanomaterials by ultrasound-assisted dispersive solid phase micro-extraction (UA-DSPME) procedure combined with spectrophotometric has been described. The Mn doped ZnS nanoparticles loaded on activated carbon were characterized by Field emission scanning electron microscopy (FE-SEM), particle size distribution, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) analyses and subsequently were used as green and efficient material for dyes accumulation. Contribution of experimental variables such as ultrasonic time, ultrasonic temperature, adsorbent mass, vortex time, ionic strength, pH and elution volume were optimized through experimental design, and while the preconcentrated analytes were efficiently eluted by acetone. Preliminary Plackett-Burman design was applied for selection of most significant factors and giving useful information about their main and interaction part of significant variables like ultrasonic time, adsorbent mass, elution volume and pH were obtained by central composite design combined with response surface analysis and optimum experimental conditions was set at pH of 8.0, 1.2mg of adsorbent, 150μL eluent and 3.7min sonication. Under optimized conditions, the average recoveries (five replicates) for two dyes (spiked at 500.0ngmL(-1)) changes in the range of 92.80-97.70% with acceptable RSD% less than 4.0% over a linear range of 3.0-5000.0ngmL(-1) for the AO and MG in water samples with regression coefficients (R(2)) of 0.9975 and 0.9977, respectively. Acceptable limits of detection of 0.91 and 0.61ngmL(-1) for AO and MG, respectively and high accuracy and repeatability are unique advantages of present method to improve the figures of merit for their accurate determination at trace level in complicated
YANG, YU; BAI, WENKUN; CHEN, YINI; LIN, YANDUAN; HU, BING
2015-01-01
The present study aimed to provide a complete exploration of the effect of sound intensity, frequency, duty cycle, microbubble volume and irradiation time on low-frequency low-intensity ultrasound (US)-mediated microvessel disruption, and to identify an optimal combination of the five factors that maximize the blockage effect. An orthogonal experimental design approach was used. Enhanced US imaging and acoustic quantification were performed to assess tumor blood perfusion. In the confirmatory test, in addition to acoustic quantification, the specimens of the tumor were stained with hematoxylin and eosin and observed using light microscopy. The results revealed that sound intensity, frequency, duty cycle, microbubble volume and irradiation time had a significant effect on the average peak intensity (API). The extent of the impact of the variables on the API was in the following order: Sound intensity; frequency; duty cycle; microbubble volume; and irradiation time. The optimum conditions were found to be as follows: Sound intensity, 1.00 W/cm2; frequency, 20 Hz; duty cycle, 40%; microbubble volume, 0.20 ml; and irradiation time, 3 min. In the confirmatory test, the API was 19.97±2.66 immediately subsequent to treatment, and histological examination revealed signs of tumor blood vessel injury in the optimum parameter combination group. In conclusion, the Taguchi L18 (3)6 orthogonal array design was successfully applied for determining the optimal parameter combination of API following treatment. Under the optimum orthogonal design condition, a minimum API of 19.97±2.66 subsequent to low-frequency and low-intensity mediated blood perfusion blockage was obtained. PMID:26722279
Marengo, E; Gianotti, V; Angioi, S; Gennaro, M C
2004-03-12
Particular attention are recently receiving antimicrobial agents added as preservatives in hygiene and cosmetics commercial products, since some of them are suspected to be harmful to the human health. The preservatives used belong to different classes of chemical species and are generally used in their mixtures. Multi-component methods able to simultaneously determinate species with different chemical structure are therefore highly required in quality control analysis. This paper presents an ion interaction RP-HPLC method for the simultaneous separation of the 20 typical antimicrobial agents most used in cosmetics and hygiene products, that are: benzoic acid, salicylic acid, 4-hydroxybenzoic acid, methyl-, ethyl-, propyl-, butyl-, benzyl-benzoate, methyl-, ethyl-, propyl-, butyl-, benzyl-paraben, o-phenyl-phenol, 4-chloro-m-cresol, triclocarban, dehydroacetic acid, bronopol, sodium pyrithione and chlorhexidine. For the development of the method and the optimization of the chromatographic conditions, an experimental design was planned and models were built by the use of artificial neural network to correlate the retention time of each analyte to the variables and their interactions. The neuronal models developed showed good predictive ability and were used, by a grid search algorithm, to optimize the chromatographic conditions for the separation of the mixture. PMID:15032350
ElShaer, Amr; Mustafa, Shelan; Kasar, Mohamad; Thapa, Sapana; Ghatora, Baljit; Alany, Raid G.
2016-01-01
Human eye is one of the most accessible organs in the body, nonetheless, its physiology and associated precorneal factors such as nasolacrimal drainage, blinking, tear film, tear turnover, and induced lacrimation has significantly decreased the residence time of any foreign substances including pharmaceutical dosage forms. Soft contact lenses are promising delivery devices that can sustain the drug release and prolong residence time by acting as a geometric barrier to drug diffusion to tear fluid. This study investigates experimental parameters such as composition of polymer mixtures, stabilizer and the amount of active pharmaceutical ingredient on the preparation of a polymeric drug delivery system for the topical ocular administration of Prednisolone. To achieve this goal, prednisolone-loaded poly (lactic-co-glycolic acid) (PLGA) nanoparticles were prepared by single emulsion solvent evaporation method. Prednisolone was quantified using a validated high performance liquid chromatography (HPLC) method. Nanoparticle size was mostly affected by the amount of co-polymer (PLGA) used whereas drug load was mostly affected by amount of prednisolone (API) used. Longer homogenization time along with higher amount of API yielded the smallest size nanoparticles. The nanoparticles prepared had an average particle size of 347.1 ± 11.9 nm with a polydispersity index of 0.081. The nanoparticles were then incorporated in the contact lens mixture before preparing them. Clear and transparent contact lenses were successfully prepared. When the nanoparticle (NP)-loaded contact lenses were compared with control contact lenses (unloaded NP contact lenses), a decrease in hydration by 2% (31.2% ± 1.25% hydration for the 0.2 g loaded NP contact lenses) and light transmission by 8% (unloaded NP contact lenses 94.5% NP 0.2 g incorporated contact lenses 86.23%). The wettability of the contact lenses remained within the desired value (<90 °C) even upon incorporation of the NP. NP alone and
ElShaer, Amr; Mustafa, Shelan; Kasar, Mohamad; Thapa, Sapana; Ghatora, Baljit; Alany, Raid G
2016-01-01
Human eye is one of the most accessible organs in the body, nonetheless, its physiology and associated precorneal factors such as nasolacrimal drainage, blinking, tear film, tear turnover, and induced lacrimation has significantly decreased the residence time of any foreign substances including pharmaceutical dosage forms. Soft contact lenses are promising delivery devices that can sustain the drug release and prolong residence time by acting as a geometric barrier to drug diffusion to tear fluid. This study investigates experimental parameters such as composition of polymer mixtures, stabilizer and the amount of active pharmaceutical ingredient on the preparation of a polymeric drug delivery system for the topical ocular administration of Prednisolone. To achieve this goal, prednisolone-loaded poly (lactic-co-glycolic acid) (PLGA) nanoparticles were prepared by single emulsion solvent evaporation method. Prednisolone was quantified using a validated high performance liquid chromatography (HPLC) method. Nanoparticle size was mostly affected by the amount of co-polymer (PLGA) used whereas drug load was mostly affected by amount of prednisolone (API) used. Longer homogenization time along with higher amount of API yielded the smallest size nanoparticles. The nanoparticles prepared had an average particle size of 347.1 ± 11.9 nm with a polydispersity index of 0.081. The nanoparticles were then incorporated in the contact lens mixture before preparing them. Clear and transparent contact lenses were successfully prepared. When the nanoparticle (NP)-loaded contact lenses were compared with control contact lenses (unloaded NP contact lenses), a decrease in hydration by 2% (31.2% ± 1.25% hydration for the 0.2 g loaded NP contact lenses) and light transmission by 8% (unloaded NP contact lenses 94.5% NP 0.2 g incorporated contact lenses 86.23%). The wettability of the contact lenses remained within the desired value (<90 °C) even upon incorporation of the NP. NP alone and
A Surrogate Approach to the Experimental Optimization of Multielement Airfoils
NASA Technical Reports Server (NTRS)
Otto, John C.; Landman, Drew; Patera, Anthony T.
1996-01-01
The incorporation of experimental test data into the optimization process is accomplished through the use of Bayesian-validated surrogates. In the surrogate approach, a surrogate for the experiment (e.g., a response surface) serves in the optimization process. The validation step of the framework provides a qualitative assessment of the surrogate quality, and bounds the surrogate-for-experiment error on designs "near" surrogate-predicted optimal designs. The utility of the framework is demonstrated through its application to the experimental selection of the trailing edge ap position to achieve a design lift coefficient for a three-element airfoil.
Optimal Network-Topology Design
NASA Technical Reports Server (NTRS)
Li, Victor O. K.; Yuen, Joseph H.; Hou, Ting-Chao; Lam, Yuen Fung
1987-01-01
Candidate network designs tested for acceptability and cost. Optimal Network Topology Design computer program developed as part of study on topology design and analysis of performance of Space Station Information System (SSIS) network. Uses efficient algorithm to generate candidate network designs consisting of subsets of set of all network components, in increasing order of total costs and checks each design to see whether it forms acceptable network. Technique gives true cost-optimal network and particularly useful when network has many constraints and not too many components. Program written in PASCAL.
Design optimization of transonic airfoils
NASA Technical Reports Server (NTRS)
Joh, C.-Y.; Grossman, B.; Haftka, R. T.
1991-01-01
Numerical optimization procedures were considered for the design of airfoils in transonic flow based on the transonic small disturbance (TSD) and Euler equations. A sequential approximation optimization technique was implemented with an accurate approximation of the wave drag based on the Nixon's coordinate straining approach. A modification of the Euler surface boundary conditions was implemented in order to efficiently compute design sensitivities without remeshing the grid. Two effective design procedures producing converged designs in approximately 10 global iterations were developed: interchanging the role of the objective function and constraint and the direct lift maximization with move limits which were fixed absolute values of the design variables.
Designing an Experimental "Accident"
ERIC Educational Resources Information Center
Picker, Lester
1974-01-01
Describes an experimental "accident" that resulted in much student learning, seeks help in the identification of nematodes, and suggests biology teachers introduce similar accidents into their teaching to stimulate student interest. (PEB)
Habitat Design Optimization and Analysis
NASA Technical Reports Server (NTRS)
SanSoucie, Michael P.; Hull, Patrick V.; Tinker, Michael L.
2006-01-01
Long-duration surface missions to the Moon and Mars will require habitats for the astronauts. The materials chosen for the habitat walls play a direct role in the protection against the harsh environments found on the surface. Choosing the best materials, their configuration, and the amount required is extremely difficult due to the immense size of the design region. Advanced optimization techniques are necessary for habitat wall design. Standard optimization techniques are not suitable for problems with such large search spaces; therefore, a habitat design optimization tool utilizing genetic algorithms has been developed. Genetic algorithms use a "survival of the fittest" philosophy, where the most fit individuals are more likely to survive and reproduce. This habitat design optimization tool is a multi-objective formulation of structural analysis, heat loss, radiation protection, and meteoroid protection. This paper presents the research and development of this tool.
Optimization of ejector design and operation
NASA Astrophysics Data System (ADS)
Kuzmenko, Konstantin; Yurchenko, Nina; Vynogradskyy, Pavlo; Paramonov, Yuriy
2016-03-01
The investigation aims at optimization of gas ejector operation. The goal consists in the improvement of the inflator design so that to enable 50 liters of gas inflation within ~30 milliseconds. For that, an experimental facility was developed and fabricated together with the measurement system to study pressure patterns in the inflator path.
Computational design and optimization of energy materials
NASA Astrophysics Data System (ADS)
Chan, Maria
The use of density functional theory (DFT) to understand and improve energy materials for diverse applications - including energy storage, thermal management, catalysis, and photovoltaics - is widespread. The further step of using high throughput DFT calculations to design materials and has led to an acceleration in materials discovery and development. Due to various limitations in DFT, including accuracy and computational cost, however, it is important to leverage effective models and, in some cases, experimental information to aid the design process. In this talk, I will discuss efforts in design and optimization of energy materials using a combination of effective models, DFT, machine learning, and experimental information.
Experimental design of a waste glass study
Piepel, G.F.; Redgate, P.E.; Hrma, P.
1995-04-01
A Composition Variation Study (CVS) is being performed to support a future high-level waste glass plant at Hanford. A total of 147 glasses, covering a broad region of compositions melting at approximately 1150{degrees}C, were tested in five statistically designed experimental phases. This paper focuses on the goals, strategies, and techniques used in designing the five phases. The overall strategy was to investigate glass compositions on the boundary and interior of an experimental region defined by single- component, multiple-component, and property constraints. Statistical optimal experimental design techniques were used to cover various subregions of the experimental region in each phase. Empirical mixture models for glass properties (as functions of glass composition) from previous phases wee used in designing subsequent CVS phases.
Design optimization of space structures
NASA Technical Reports Server (NTRS)
Felippa, Carlos
1991-01-01
The topology-shape-size optimization of space structures is investigated through Kikuchi's homogenization method. The method starts from a 'design domain block,' which is a region of space into which the structure is to materialize. This domain is initially filled with a finite element mesh, typically regular. Force and displacement boundary conditions corresponding to applied loads and supports are applied at specific points in the domain. An optimal structure is to be 'carved out' of the design under two conditions: (1) a cost function is to be minimized, and (2) equality or inequality constraints are to be satisfied. The 'carving' process is accomplished by letting microstructure holes develop and grow in elements during the optimization process. These holes have a rectangular shape in two dimensions and a cubical shape in three dimensions, and may also rotate with respect to the reference axes. The properties of the perforated element are obtained through an homogenization procedure. Once a hole reaches the volume of the element, that element effectively disappears. The project has two phases. In the first phase the method was implemented as the combination of two computer programs: a finite element module, and an optimization driver. In the second part, focus is on the application of this technique to planetary structures. The finite element part of the method was programmed for the two-dimensional case using four-node quadrilateral elements to cover the design domain. An element homogenization technique different from that of Kikuchi and coworkers was implemented. The optimization driver is based on an augmented Lagrangian optimizer, with the volume constraint treated as a Courant penalty function. The optimizer has to be especially tuned to this type of optimization because the number of design variables can reach into the thousands. The driver is presently under development.
Design of optimal systolic arrays
Li, G.J.; Wah, B.W.
1985-01-01
Conventional design of systolic arrays is based on the mapping of an algorithm onto an interconnection of processing elements in a VLSI chip. This mapping is done in an ad hoc manner, and the resulting configuration usually represents a feasible but suboptimal design. In this paper, systolic arrays are characterized by three classes of parameters: the velocities of data flows, the spatial distributions of data, and the periods of computation. By relating these parameters in constraint equations that govern the correctness of the design, the design is formulated into an optimization problem. The size of the search space is a polynomial of the problem size, and a methodology to systematically search and reduce this space and to obtain the optimal design is proposed. Some examples of applying the method, including matrix multiplication, finite impulse response filtering, deconvolution, and triangular-matrix inversion, are given. 30 references.
Spin bearing retainer design optimization
NASA Technical Reports Server (NTRS)
Boesiger, Edward A.; Warner, Mark H.
1991-01-01
The dynamics behavior of spin bearings for momentum wheels (control-moment gyroscope, reaction wheel assembly) is critical to satellite stability and life. Repeated bearing retainer instabilities hasten lubricant deterioration and can lead to premature bearing failure and/or unacceptable vibration. These instabilities are typically distinguished by increases in torque, temperature, audible noise, and vibration induced by increases into the bearing cartridge. Ball retainer design can be optimized to minimize these occurrences. A retainer was designed using a previously successful smaller retainer as an example. Analytical methods were then employed to predict its behavior and optimize its configuration.
Optimization process in helicopter design
NASA Technical Reports Server (NTRS)
Logan, A. H.; Banerjee, D.
1984-01-01
In optimizing a helicopter configuration, Hughes Helicopters uses a program called Computer Aided Sizing of Helicopters (CASH), written and updated over the past ten years, and used as an important part of the preliminary design process of the AH-64. First, measures of effectiveness must be supplied to define the mission characteristics of the helicopter to be designed. Then CASH allows the designer to rapidly and automatically develop the basic size of the helicopter (or other rotorcraft) for the given mission. This enables the designer and management to assess the various tradeoffs and to quickly determine the optimum configuration.
Global Design Optimization for Fluid Machinery Applications
NASA Technical Reports Server (NTRS)
Shyy, Wei; Papila, Nilay; Tucker, Kevin; Vaidyanathan, Raj; Griffin, Lisa
2000-01-01
Recent experiences in utilizing the global optimization methodology, based on polynomial and neural network techniques for fluid machinery design are summarized. Global optimization methods can utilize the information collected from various sources and by different tools. These methods offer multi-criterion optimization, handle the existence of multiple design points and trade-offs via insight into the entire design space can easily perform tasks in parallel, and are often effective in filtering the noise intrinsic to numerical and experimental data. Another advantage is that these methods do not need to calculate the sensitivity of each design variable locally. However, a successful application of the global optimization method needs to address issues related to data requirements with an increase in the number of design variables and methods for predicting the model performance. Examples of applications selected from rocket propulsion components including a supersonic turbine and an injector element and a turbulent flow diffuser are used to illustrate the usefulness of the global optimization method.
Experimental Investigation of Optimal Adhesion of Mushroomlike Elastomer Microfibrillar Adhesives.
Marvi, Hamidreza; Song, Sukho; Sitti, Metin
2015-09-22
Optimal fiber designs for the maximal pull-off force have been indispensable for increasing the attachment performance of recently introduced gecko-inspired reversible micro/nanofibrillar adhesives. There are several theoretical studies on such optimal designs; however, due to the lack of three-dimensional (3D) fabrication techniques that can fabricate such optimal designs in 3D, there have not been many experimental investigations on this challenge. In this study, we benefitted from recent advances in two-photon lithography techniques to fabricate mushroomlike polyurethane elastomer fibers with different aspect ratios of tip to stalk diameter (β) and tip wedge angles (θ) to investigate the effect of these two parameters on the pull-off force. We found similar trends to those predicted theoretically. We found that β has an impact on the slope of the force-displacement curve while both β and θ play a role in the stress distribution and crack propagation. We found that these effects are coupled and the optimal set of parameters also depends on the fiber material. This is the first experimental verification of such optimal designs proposed for mushroomlike microfibers. This experimental approach could be used to evaluate a wide range of complex microstructured adhesive designs suggested in the literature and optimize them. PMID:26322396
A Tutorial on Adaptive Design Optimization
Myung, Jay I.; Cavagnaro, Daniel R.; Pitt, Mark A.
2013-01-01
Experimentation is ubiquitous in the field of psychology and fundamental to the advancement of its science, and one of the biggest challenges for researchers is designing experiments that can conclusively discriminate the theoretical hypotheses or models under investigation. The recognition of this challenge has led to the development of sophisticated statistical methods that aid in the design of experiments and that are within the reach of everyday experimental scientists. This tutorial paper introduces the reader to an implementable experimentation methodology, dubbed Adaptive Design Optimization, that can help scientists to conduct “smart” experiments that are maximally informative and highly efficient, which in turn should accelerate scientific discovery in psychology and beyond. PMID:23997275
Acoustic design by topology optimization
NASA Astrophysics Data System (ADS)
Dühring, Maria B.; Jensen, Jakob S.; Sigmund, Ole
2008-11-01
To bring down noise levels in human surroundings is an important issue and a method to reduce noise by means of topology optimization is presented here. The acoustic field is modeled by Helmholtz equation and the topology optimization method is based on continuous material interpolation functions in the density and bulk modulus. The objective function is the squared sound pressure amplitude. First, room acoustic problems are considered and it is shown that the sound level can be reduced in a certain part of the room by an optimized distribution of reflecting material in a design domain along the ceiling or by distribution of absorbing and reflecting material along the walls. We obtain well defined optimized designs for a single frequency or a frequency interval for both 2D and 3D problems when considering low frequencies. Second, it is shown that the method can be applied to design outdoor sound barriers in order to reduce the sound level in the shadow zone behind the barrier. A reduction of up to 10 dB for a single barrier and almost 30 dB when using two barriers are achieved compared to utilizing conventional sound barriers.
Gandolfi, F; Malleret, L; Sergent, M; Doumenq, P
2015-08-01
The water framework directives (WFD 2000/60/EC and 2013/39/EU) force European countries to monitor the quality of their aquatic environment. Among the priority hazardous substances targeted by the WFD, short chain chlorinated paraffins C10-C13 (SCCPs), still represent an analytical challenge, because few laboratories are nowadays able to analyze them. Moreover, an annual average quality standards as low as 0.4μgL(-1) was set for SCCPs in surface water. Therefore, to test for compliance, the implementation of sensitive and reliable analysis method of SCCPs in water are required. The aim of this work was to address this issue by evaluating automated solid phase micro-extraction (SPME) combined on line with gas chromatography-electron capture negative ionization mass spectrometry (GC/ECNI-MS). Fiber polymer, extraction mode, ionic strength, extraction temperature and time were the most significant thermodynamic and kinetic parameters studied. To determine the suitable factors working ranges, the study of the extraction conditions was first carried out by using a classical one factor-at-a-time approach. Then a mixed level factorial 3×2(3) design was performed, in order to give rise to the most influent parameters and to estimate potential interactions effects between them. The most influent factors, i.e. extraction temperature and duration, were optimized by using a second experimental design, in order to maximize the chromatographic response. At the close of the study, a method involving headspace SPME (HS-SPME) coupled to GC/ECNI-MS is proposed. The optimum extraction conditions were sample temperature 90°C, extraction time 80min, with the PDMS 100μm fiber and desorption at 250°C during 2min. Linear response from 0.2ngmL(-1) to 10ngmL(-1) with r(2)=0.99 and limits of detection and quantification, respectively of 4pgmL(-1) and 120pgmL(-1) in MilliQ water, were achieved. The method proved to be applicable in different types of waters and show key advantages, such
Experimental design in chemistry: A tutorial.
Leardi, Riccardo
2009-10-12
In this tutorial the main concepts and applications of experimental design in chemistry will be explained. Unfortunately, nowadays experimental design is not as known and applied as it should be, and many papers can be found in which the "optimization" of a procedure is performed one variable at a time. Goal of this paper is to show the real advantages in terms of reduced experimental effort and of increased quality of information that can be obtained if this approach is followed. To do that, three real examples will be shown. Rather than on the mathematical aspects, this paper will focus on the mental attitude required by experimental design. The readers being interested to deepen their knowledge of the mathematical and algorithmical part can find very good books and tutorials in the references [G.E.P. Box, W.G. Hunter, J.S. Hunter, Statistics for Experimenters: An Introduction to Design, Data Analysis, and Model Building, John Wiley & Sons, New York, 1978; R. Brereton, Chemometrics: Data Analysis for the Laboratory and Chemical Plant, John Wiley & Sons, New York, 1978; R. Carlson, J.E. Carlson, Design and Optimization in Organic Synthesis: Second Revised and Enlarged Edition, in: Data Handling in Science and Technology, vol. 24, Elsevier, Amsterdam, 2005; J.A. Cornell, Experiments with Mixtures: Designs, Models and the Analysis of Mixture Data, in: Series in Probability and Statistics, John Wiley & Sons, New York, 1991; R.E. Bruns, I.S. Scarminio, B. de Barros Neto, Statistical Design-Chemometrics, in: Data Handling in Science and Technology, vol. 25, Elsevier, Amsterdam, 2006; D.C. Montgomery, Design and Analysis of Experiments, 7th edition, John Wiley & Sons, Inc., 2009; T. Lundstedt, E. Seifert, L. Abramo, B. Thelin, A. Nyström, J. Pettersen, R. Bergman, Chemolab 42 (1998) 3; Y. Vander Heyden, LC-GC Europe 19 (9) (2006) 469]. PMID:19786177
Optimal design of solidification processes
NASA Technical Reports Server (NTRS)
Dantzig, Jonathan A.; Tortorelli, Daniel A.
1991-01-01
An optimal design algorithm is presented for the analysis of general solidification processes, and is demonstrated for the growth of GaAs crystals in a Bridgman furnace. The system is optimal in the sense that the prespecified temperature distribution in the solidifying materials is obtained to maximize product quality. The optimization uses traditional numerical programming techniques which require the evaluation of cost and constraint functions and their sensitivities. The finite element method is incorporated to analyze the crystal solidification problem, evaluate the cost and constraint functions, and compute the sensitivities. These techniques are demonstrated in the crystal growth application by determining an optimal furnace wall temperature distribution to obtain the desired temperature profile in the crystal, and hence to maximize the crystal's quality. Several numerical optimization algorithms are studied to determine the proper convergence criteria, effective 1-D search strategies, appropriate forms of the cost and constraint functions, etc. In particular, we incorporate the conjugate gradient and quasi-Newton methods for unconstrained problems. The efficiency and effectiveness of each algorithm is presented in the example problem.
Research on optimization-based design
NASA Technical Reports Server (NTRS)
Balling, R. J.; Parkinson, A. R.; Free, J. C.
1989-01-01
Research on optimization-based design is discussed. Illustrative examples are given for cases involving continuous optimization with discrete variables and optimization with tolerances. Approximation of computationally expensive and noisy functions, electromechanical actuator/control system design using decomposition and application of knowledge-based systems and optimization for the design of a valve anti-cavitation device are among the topics covered.
Optimal design of capacitor-driven coilgun
NASA Astrophysics Data System (ADS)
Kim, Seog-Whan; Jung, Hyun-Kyo; Hahn, Song-Yop
1994-03-01
This paper presents an analysis and optimal design of a capacitor-driven inductive coilgun. An equivalent circuit is used for a launch simulation of the coilgun. The circuit equations are solved together with the equation of motion of the projectile by using the Runge-Kutta method. The numerical results are compared with the experimental values to verify the usefulness of the developed simulation program. It is shown that the numerical and the experimental results are in a good agreement. In the design of the system the optimization is achieved by employing the genetic algorithm. The resultant specifications of the coilgun optimally designed by the proposed algorithm are tested by experiment. Finally the obtained results are compared with those designed by approximate equations and by linear search methods as well. It is found that the proposed algorithm gives a better result in the energy efficiency of the system, namely it enables one to obtain a higher muzzle velocity of the projectile with the same amount of energy.
Optimization of confocal scanning laser ophthalmoscope design
Dhalla, Al-Hafeez; Kelly, Michael P.; Farsiu, Sina; Izatt, Joseph A.
2013-01-01
Abstract. Confocal scanning laser ophthalmoscopy (cSLO) enables high-resolution and high-contrast imaging of the retina by employing spatial filtering for scattered light rejection. However, to obtain optimized image quality, one must design the cSLO around scanner technology limitations and minimize the effects of ocular aberrations and imaging artifacts. We describe a cSLO design methodology resulting in a simple, relatively inexpensive, and compact lens-based cSLO design optimized to balance resolution and throughput for a 20-deg field of view (FOV) with minimal imaging artifacts. We tested the imaging capabilities of our cSLO design with an experimental setup from which we obtained fast and high signal-to-noise ratio (SNR) retinal images. At lower FOVs, we were able to visualize parafoveal cone photoreceptors and nerve fiber bundles even without the use of adaptive optics. Through an experiment comparing our optimized cSLO design to a commercial cSLO system, we show that our design demonstrates a significant improvement in both image quality and resolution. PMID:23864013
Madgulkar, Ashwini; Bhalekar, Mangesh; Swami, Megha
2009-01-01
The aim of the present research work was to develop release modulated beads of losartan potassium complexed with anion exchange resin, Duolite AP143 (cholestyramine). Chitosan was selected as a hydrophilic polymer for the formation of beads which could sustain the release of the drug up to 12 h, along with drug resin complex (DRC). Chitosan beads were prepared using an in-liquid curing method by ionotropic cross-linking or interpolymer linkage with sodium tripolyphosphate (TPP). The formulation of the beads was optimized for entrapment efficiency and drug release using 3(2) full factorial design. The independent variables selected were DRC/chitosan and percent of TPP. The optimization model was validated for its performance characteristics. Studies revealed that as the concentration of chitosan and TPP was increased, entrapment efficiency and the drug release were found to increase and decrease, respectively. The swelling capacity of chitosan-TPP beads decreased with increasing concentration of TPP. The effect of chitosan concentration and percentage of TPP solution used for cross-linking on entrapment efficiency and drug release rate was extensively investigated. Optimized beads were subjected to in vivo studies in Wistar albino rats to determine the mean arterial blood pressure and compared with marketed formulation. The pharmacodynamic study demonstrates steady blood pressure control for optimized formulation as compared to fluctuated blood pressure for the marketed formulation. PMID:19495989
Design Of Theoretically Optimal Thermoacoustic Cooling Device
NASA Astrophysics Data System (ADS)
Tisovský, Tomáš; Vít, Tomáš
2016-03-01
The aim of this article is to design theoretically optimal thermoacoustic cooling device. The opening chapter gives the reader brief introduction to thermoacoustic, specializing in the thermoacoustic principle in refrigerator regime. Subsequent part of the article aims to explain the principle on which thermoacoustic is simulated in DeltaEC. Numbers of executed numerical simulations are listed and the resulting thermoacoustic cooling device design is presented along with its main operation characteristics. In conclusion, recommendations for future experimental work are given and the results are discussed.
NASA Astrophysics Data System (ADS)
Appiah, Williams Agyei; Park, Joonam; Song, Seonghyun; Byun, Seoungwoo; Ryou, Myung-Hyun; Lee, Yong Min
2016-07-01
LiNi0.6Co0.2Mn0.2O2 cathodes of different thicknesses and porosities are prepared and tested, in order to optimize the design of lithium-ion cells. A mathematical model for simulating multiple types of particles with different contact resistances in a single electrode is adopted to study the effects of the different cathode thicknesses and porosities on lithium-ion transport using the nonlinear least squares technique. The model is used to optimize the design of LiNi0.6Co0.2Mn0.2O2/graphite lithium-ion cells by employing it to generate a number of Ragone plots. The cells are optimized for cathode porosity and thickness, while the anode porosity, anode-to-cathode capacity ratio, thickness and porosity of separator, and electrolyte salt concentration are held constant. Optimization is performed for discharge times ranging from 10 h to 5 min. Using the Levenberg-Marquardt method as a fitting technique, accounting for multiple particles with different contact resistances, and employing a rate-dependent solid-phase diffusion coefficient results in there being good agreement between the simulated and experimentally determined discharge curves. The optimized parameters obtained from this study should serve as a guide for the battery industry as well as for researchers for determining the optimal cell design for different applications.
Rogez-Florent, Tiphaine; Foulon, Catherine; Six, Perrine; Goossens, Laurence; Danel, Cécile; Goossens, Jean-François
2014-10-01
A CE method using dual cationic and neutral cyclodextrins (CD) was optimized for the enantiomeric separation of a compound presenting a diaryl sulfonamide group. Preliminary studies were made to select the optimal CDs and pH of the BGE. Two CDs (amino-β-CD and β-CD) were selected to separate the enantiomers in a 67 mM phosphate buffer at pH 7.4. However, the repeatability of the analyses obtained on bare-fused silica capillary was not acceptable owing to the adsorption of the amino-β-CD to the capillary. To prevent this, a dynamic coating of the capillary was used employing five layers of ionic-polymer (poly(diallyldimethylammonium) chloride (PDADMAC) and poly(sodium 4-styrenesulfonate). The efficiency of the coating was assessed by measuring the EOF stability. Repeatability of the injections was obtained when intermediate coating with PDADMAC was performed between each run. Secondly, this enantioseparation method was optimized using a central composite circumscribed design including three factors: amino-β-CD and β-CD concentrations and the percentage of methanol. Under the optimal conditions (i.e. 16.6 mM of amino-β-CD, 2.6 mM of β-CD, 0% MeOH in 67 mM phosphate buffer (pH 7.4) as BGE, cathodic injection 0.5 psi, 5 s, separation voltage 15 kV and a temperature of 15°C), complete enantioresolution of the analyte was obtained. It is worth mentioning that the design of experiments (DOE) protocol employed showed a significant interaction between CDs, highlighting the utility of DOE in method development. Finally, small variations in the ionic-polymer concentrations did not significantly influence the EOF, confirming the robustness of the coating method. PMID:24723380
Optimal design of airlift fermenters
Moresi, M.
1981-11-01
In this article a modeling of a draft-tube airlift fermenter (ALF) based on perfect back-mixing of liquid and plugflow for gas bubbles has been carried out to optimize the design and operation of fermentation units at different working capacities. With reference to a whey fermentation by yeasts the economic optimization has led to a slim ALF with an aspect ratio of about 15. As far as power expended per unit of oxygen transfer is concerned, the responses of the model are highly influenced by kLa. However, a safer use of the model has been suggested in order to assess the feasibility of the fermentation process under study. (Refs. 39).
NASA Astrophysics Data System (ADS)
Chamkouri, Narges; Niazi, Ali; Zare-Shahabadi, Vali
2016-03-01
A novel pH optical sensor was prepared by immobilizing an azo dye called Janus Green B on the triacetylcellulose membrane. Condition of the dye solution used in the immobilization step, including concentration of the dye, pH, and duration were considered and optimized using the Box-Behnken design. The proposed sensor showed good behavior and precision (RSD < 5%) in the pH range of 2.0-10.0. Advantages of this optical sensor include on-line applicability, no leakage, long-term stability (more than 6 months), fast response time (less than 1 min), high selectivity and sensitivity as well as good reversibility and reproducibility.
Computational Optimization of a Natural Laminar Flow Experimental Wing Glove
NASA Technical Reports Server (NTRS)
Hartshom, Fletcher
2012-01-01
Computational optimization of a natural laminar flow experimental wing glove that is mounted on a business jet is presented and discussed. The process of designing a laminar flow wing glove starts with creating a two-dimensional optimized airfoil and then lofting it into a three-dimensional wing glove section. The airfoil design process does not consider the three dimensional flow effects such as cross flow due wing sweep as well as engine and body interference. Therefore, once an initial glove geometry is created from the airfoil, the three dimensional wing glove has to be optimized to ensure that the desired extent of laminar flow is maintained over the entire glove. TRANAIR, a non-linear full potential solver with a coupled boundary layer code was used as the main tool in the design and optimization process of the three-dimensional glove shape. The optimization process uses the Class-Shape-Transformation method to perturb the geometry with geometric constraints that allow for a 2-in clearance from the main wing. The three-dimensional glove shape was optimized with the objective of having a spanwise uniform pressure distribution that matches the optimized two-dimensional pressure distribution as closely as possible. Results show that with the appropriate inputs, the optimizer is able to match the two dimensional pressure distributions practically across the entire span of the wing glove. This allows for the experiment to have a much higher probability of having a large extent of natural laminar flow in flight.
Parametric Design Optimization By Integrating CAD Systems And Optimization Tools
NASA Astrophysics Data System (ADS)
Rehan, M.; Olabi, A. G.
2009-11-01
Designing a cost effective product in minimum time is a complex process. In order to achieve this goal the requirement of optimum designs are becoming more important. One of the time consuming factor in the design optimization cycle is the modifications of Computer Aided Design (CAD) model after optimization. In conventional design optimization techniques the design engineer has to update the CAD model after receiving optimum design from optimization tools. It is worthwhile using parametric design optimization process to minimize the optimization cycle time. This paper presents a comprehensive study to integrate the optimization parameters between CAD system and optimization tools which were driven from a single user environment. Finally, design optimization of a Compressed Natural Gas (CNG) cylinder was implemented as case study. In this case study the optimization tools were fully integrated with CAD system, therefore, all the deliverables including; part design, drawings and assembly can be automatically updated after achieving the optimum geometry having minimum volume and satisfying all imposed constraints.
Bianchi, F; Maffini, M; Mangia, A; Marengo, E; Mucchino, C
2007-01-17
A chemometric approach based on experimental design and desirability functions was used to develop and validated a method for the determination of some metals of biological concern by a fast sequential ICP-AES. The elements considered are Al, Fe, Mn, Zn, Li, Na and K. The experimental design was used to investigate the effects of three instrumental most crucial parameters, such as sheath gas flow rate, pump speed and auxiliary gas flow rate. In order to improve the multielemental analysis speed, although a sequential instrument allows the use of a separate parameter set for each wavelength, regression models and desirability functions were applied to find the experimental conditions providing the highest global sensitivity. Validation was performed in terms of limits of detection (LOD), limits of quantitation (LOQ), linearity, precision and recovery. By using the 167.02 nm wavelength, aluminium LOD was 0.5 microg L(-1) while the highest LOD was found for K (65 microg L(-1)). A linear range of at least three orders of magnitude was statistically demonstrated for each element. Precision was evaluated by testing two concentration levels, and good results in terms of intra-day repeatability were obtained, with R.S.D. values lower than 4.1% at the lowest concentration level. Lacking a suitable certified reference material, trueness was estimated using the recovery rate on fortified samples. The validated method was then used in the quantification of the elements considered in a serum sample. PMID:17079109
Probabilistic Finite Element Analysis & Design Optimization for Structural Designs
NASA Astrophysics Data System (ADS)
Deivanayagam, Arumugam
This study focuses on implementing probabilistic nature of material properties (Kevlar® 49) to the existing deterministic finite element analysis (FEA) of fabric based engine containment system through Monte Carlo simulations (MCS) and implementation of probabilistic analysis in engineering designs through Reliability Based Design Optimization (RBDO). First, the emphasis is on experimental data analysis focusing on probabilistic distribution models which characterize the randomness associated with the experimental data. The material properties of Kevlar® 49 are modeled using experimental data analysis and implemented along with an existing spiral modeling scheme (SMS) and user defined constitutive model (UMAT) for fabric based engine containment simulations in LS-DYNA. MCS of the model are performed to observe the failure pattern and exit velocities of the models. Then the solutions are compared with NASA experimental tests and deterministic results. MCS with probabilistic material data give a good prospective on results rather than a single deterministic simulation results. The next part of research is to implement the probabilistic material properties in engineering designs. The main aim of structural design is to obtain optimal solutions. In any case, in a deterministic optimization problem even though the structures are cost effective, it becomes highly unreliable if the uncertainty that may be associated with the system (material properties, loading etc.) is not represented or considered in the solution process. Reliable and optimal solution can be obtained by performing reliability optimization along with the deterministic optimization, which is RBDO. In RBDO problem formulation, in addition to structural performance constraints, reliability constraints are also considered. This part of research starts with introduction to reliability analysis such as first order reliability analysis, second order reliability analysis followed by simulation technique that
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.
Teaching experimental design to biologists.
Zolman, J F
1999-12-01
The teaching of research design and data analysis to our graduate students has been a persistent problem. A course is described in which students, early in their graduate training, obtain extensive practice in designing experiments and interpreting data. Lecture-discussions on the essentials of biostatistics are given, and then these essentials are repeatedly reviewed by illustrating their applications and misapplications in numerous research design problems. Students critique these designs and prepare similar problems for peer evaluation. In most problems the treatments are confounded by extraneous variables, proper controls may be absent, or data analysis may be incorrect. For each problem, students must decide whether the researchers' conclusions are valid and, if not, must identify a fatal experimental flaw. Students learn that an experiment is a well-conceived plan for data collection, analysis, and interpretation. They enjoy the interactive evaluations of research designs and appreciate the repetitive review of common flaws in different experiments. They also benefit from their practice in scientific writing and in critically evaluating their peers' designs. PMID:10644236
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.
Szerkus, O; Jacyna, J; Wiczling, P; Gibas, A; Sieczkowski, M; Siluk, D; Matuszewski, M; Kaliszan, R; Markuszewski, M J
2016-09-01
Fluoroquinolones are considered as gold standard for the prevention of bacterial infections after transrectal ultrasound guided prostate biopsy. However, recent studies reported that fluoroquinolone- resistant bacterial strains are responsible for gradually increasing number of infections after transrectal prostate biopsy. In daily clinical practice, antibacterial efficacy is evaluated only in vitro, by measuring the reaction of bacteria with an antimicrobial agent in culture media (i.e. calculation of minimal inhibitory concentration). Such approach, however, has no relation to the treated tissue characteristics and might be highly misleading. Thus, the objective of this study was to develop, with the use of Design of Experiments approach, a reliable, specific and sensitive ultra-high performance liquid chromatography- diode array detection method for the quantitative analysis of levofloxacin in plasma and prostate tissue samples obtained from patients undergoing prostate biopsy. Moreover, correlation study between concentrations observed in plasma samples vs prostatic tissue samples was performed, resulting in better understanding, evaluation and optimization of the fluoroquinolone-based antimicrobial prophylaxis during transrectal ultrasound guided prostate biopsy. Box-Behnken design was employed to optimize chromatographic conditions of the isocratic elution program in order to obtain desirable retention time, peak symmetry and resolution of levofloxacine and ciprofloxacine (internal standard) peaks. Fractional Factorial design 2(4-1) with four center points was used for screening of significant factors affecting levofloxacin extraction from the prostatic tissue. Due to the limited number of tissue samples the prostatic sample preparation procedure was further optimized using Central Composite design. Design of Experiments approach was also utilized for evaluation of parameter robustness. The method was found linear over the range of 0.030-10μg/mL for human
An Evolutionary Optimization System for Spacecraft Design
NASA Technical Reports Server (NTRS)
Fukunaga, A.; Stechert, A.
1997-01-01
Spacecraft design optimization is a domian that can benefit from the application of optimization algorithms such as genetic algorithms. In this paper, we describe DEVO, an evolutionary optimization system that addresses these issues and provides a tool that can be applied to a number of real-world spacecraft design applications. We describe two current applications of DEVO: physical design if a Mars Microprobe Soil Penetrator, and system configuration optimization for a Neptune Orbiter.
Optimal design of compact spur gear reductions
NASA Technical Reports Server (NTRS)
Savage, M.; Lattime, S. B.; Kimmel, J. A.; Coe, H. H.
1992-01-01
The optimal design of compact spur gear reductions includes the selection of bearing and shaft proportions in addition to gear mesh parameters. Designs for single mesh spur gear reductions are based on optimization of system life, system volume, and system weight including gears, support shafts, and the four bearings. The overall optimization allows component properties to interact, yielding the best composite design. A modified feasible directions search algorithm directs the optimization through a continuous design space. Interpolated polynomials expand the discrete bearing properties and proportions into continuous variables for optimization. After finding the continuous optimum, the designer can analyze near optimal designs for comparison and selection. Design examples show the influence of the bearings on the optimal configurations.
Experimental Validation of an Integrated Controls-Structures Design Methodology
NASA Technical Reports Server (NTRS)
Maghami, Peiman G.; Gupta, Sandeep; Elliot, Kenny B.; Walz, Joseph E.
1996-01-01
The first experimental validation of an integrated controls-structures design methodology for a class of large order, flexible space structures is described. Integrated redesign of the controls-structures-interaction evolutionary model, a laboratory testbed at NASA Langley, was described earlier. The redesigned structure was fabricated, assembled in the laboratory, and experimentally tested against the original structure. Experimental results indicate that the structure redesigned using the integrated design methodology requires significantly less average control power than the nominal structure with control-optimized designs, while maintaining the required line-of-sight pointing performance. Thus, the superiority of the integrated design methodology over the conventional design approach is experimentally demonstrated. Furthermore, amenability of the integrated design structure to other control strategies is evaluated, both analytically and experimentally. Using Linear-Quadratic-Guassian optimal dissipative controllers, it is observed that the redesigned structure leads to significantly improved performance with alternate controllers as well.
Rational Experimental Design for Electrical Resistivity Imaging
NASA Astrophysics Data System (ADS)
Mitchell, V.; Pidlisecky, A.; Knight, R.
2008-12-01
Over the past several decades advances in the acquisition and processing of electrical resistivity data, through multi-channel acquisition systems and new inversion algorithms, have greatly increased the value of these data to near-surface environmental and hydrological problems. There has, however, been relatively little advancement in the design of actual surveys. Data acquisition still typically involves using a small number of traditional arrays (e.g. Wenner, Schlumberger) despite a demonstrated improvement in data quality from the use of non-standard arrays. While optimized experimental design has been widely studied in applied mathematics and the physical and biological sciences, it is rarely implemented for non-linear problems, such as electrical resistivity imaging (ERI). We focus specifically on using ERI in the field for monitoring changes in the subsurface electrical resistivity structure. For this application we seek an experimental design method that can be used in the field to modify the data acquisition scheme (spatial and temporal sampling) based on prior knowledge of the site and/or knowledge gained during the imaging experiment. Some recent studies have investigated optimized design of electrical resistivity surveys by linearizing the problem or with computationally-intensive search algorithms. We propose a method for rational experimental design based on the concept of informed imaging, the use of prior information regarding subsurface properties and processes to develop problem-specific data acquisition and inversion schemes. Specifically, we use realistic subsurface resistivity models to aid in choosing source configurations that maximize the information content of our data. Our approach is based on first assessing the current density within a region of interest, in order to provide sufficient energy to the region of interest to overcome a noise threshold, and then evaluating the direction of current vectors, in order to maximize the
Piezoelectric transducer design via multiobjective optimization.
Fu, B; Hemsel, T; Wallaschek, J
2006-12-22
The design of piezoelectric transducers is usually based on single-objective optimization only. In most practical applications of piezoelectric transducers, however, there exist multiple design objectives that often are contradictory to each other by their very nature. It is impossible to find a solution at which each objective function gets its optimal value simultaneously. Our design approach is to first find a set of Pareto-optimal solutions, which can be considered to be best compromises among multiple design objectives. Among these Pareto-optimal solutions, the designer can then select the one solution which he considers to be the best one. In this paper we investigate the optimal design of a Langevin transducer. The design problem is formulated mathematically as a constrained multiobjective optimization problem. The maximum vibration amplitude and the minimum electrical input power are considered as optimization objectives. Design variables involve continuous variables (dimensions of the transducer) and discrete variables (the number of piezoelectric rings and material types). In order to formulate the optimization problem, the behavior of piezoelectric transducers is modeled using the transfer matrix method based on analytical models. Multiobjective evolutionary algorithms are applied in the optimization process and a set of Pareto-optimal designs is calculated. The optimized results are analyzed and the preferred design is determined. PMID:16814826
Design optimization method for Francis turbine
NASA Astrophysics Data System (ADS)
Kawajiri, H.; Enomoto, Y.; Kurosawa, S.
2014-03-01
This paper presents a design optimization system coupled CFD. Optimization algorithm of the system employs particle swarm optimization (PSO). Blade shape design is carried out in one kind of NURBS curve defined by a series of control points. The system was applied for designing the stationary vanes and the runner of higher specific speed francis turbine. As the first step, single objective optimization was performed on stay vane profile, and second step was multi-objective optimization for runner in wide operating range. As a result, it was confirmed that the design system is useful for developing of hydro turbine.
Animal husbandry and experimental design.
Nevalainen, Timo
2014-01-01
If the scientist needs to contact the animal facility after any study to inquire about husbandry details, this represents a lost opportunity, which can ultimately interfere with the study results and their interpretation. There is a clear tendency for authors to describe methodological procedures down to the smallest detail, but at the same time to provide minimal information on animals and their husbandry. Controlling all major variables as far as possible is the key issue when establishing an experimental design. The other common mechanism affecting study results is a change in the variation. Factors causing bias or variation changes are also detectable within husbandry. Our lives and the lives of animals are governed by cycles: the seasons, the reproductive cycle, the weekend-working days, the cage change/room sanitation cycle, and the diurnal rhythm. Some of these may be attributable to routine husbandry, and the rest are cycles, which may be affected by husbandry procedures. Other issues to be considered are consequences of in-house transport, restrictions caused by caging, randomization of cage location, the physical environment inside the cage, the acoustic environment audible to animals, olfactory environment, materials in the cage, cage complexity, feeding regimens, kinship, and humans. Laboratory animal husbandry issues are an integral but underappreciated part of investigators' experimental design, which if ignored can cause major interference with the results. All researchers should familiarize themselves with the current routine animal care of the facility serving them, including their capabilities for the monitoring of biological and physicochemical environment. PMID:25541541
Hashemi, Payman; Rahmani, Zohreh
2006-02-28
Homocystine was for the first time, chemically linked to a highly cross-linked agarose support (Novarose) to be employed as a chelating adsorbent for preconcentration and AAS determination of nickel in table salt and baking soda. Nickel is quantitatively adsorbed on a small column packed with 0.25ml of the adsorbent, in a pH range of 5.5-6.5 and simply eluted with 5ml of a 1moll(-1) hydrochloric acid solution. A factorial design was used for optimization of the effects of five different variables on the recovery of nickel. The results indicated that the factors of flow rate and column length, and the interactions between pH and sample volume are significant. In the optimized conditions, the column could tolerate salt concentrations up to 0.5moll(-1) and sample volumes beyond 500ml. Matrix ions of Mg(2+) and Ca(2+), with a concentration of 200mgl(-1), and potentially interfering ions of Cd(2+), Cu(2+), Zn(2+) and Mn(2+), with a concentration of 10mgl(-1), did not have significant effect on the analyte's signal. Preconcentration factors up to 100 and a detection limit of 0.49mugl(-1), corresponding to an enrichment volume of 500ml, were obtained for the determination of the analyte by flame AAS. Application of the method to the determination of natural and spiked nickel in table salt and baking soda solutions resulted in quantitative recoveries. Direct ETAAS determination of nickel in the same samples was not possible because of a high background observed. PMID:18970514
Optimizing experimental parameters for tracking of diffusing particles
NASA Astrophysics Data System (ADS)
Vestergaard, Christian L.
2016-08-01
We describe how a single-particle tracking experiment should be designed in order for its recorded trajectories to contain the most information about a tracked particle's diffusion coefficient. The precision of estimators for the diffusion coefficient is affected by motion blur, limited photon statistics, and the length of recorded time series. We demonstrate for a particle undergoing free diffusion that precision is negligibly affected by motion blur in typical experiments, while optimizing photon counts and the number of recorded frames is the key to precision. Building on these results, we describe for a wide range of experimental scenarios how to choose experimental parameters in order to optimize the precision. Generally, one should choose quantity over quality: experiments should be designed to maximize the number of frames recorded in a time series, even if this means lower information content in individual frames.
Optimal design of biaxial tensile cruciform specimens
NASA Astrophysics Data System (ADS)
Demmerle, S.; Boehler, J. P.
1993-01-01
F OR EXPERIMENTAL investigations concerning the mechanical behaviour under biaxial stress states of rolled sheet metals, mostly cruciform flat specimens are used. By means of empirical methods, different specimen geometries have been proposed in the literature. In order to evaluate the suitability of a specimen design, a mathematically well defined criterion is developed, based on the standard deviations of the values of the stresses in the test section. Applied to the finite element method, the criterion is employed to realize the shape optimization of biaxial cruciform specimens for isotropic elastic materials. Furthermore, the performance of the obtained optimized specimen design is investigated in the case of off-axes tests on anisotropic materials. Therefore, for the first time, an original testing device, consisting of hinged fixtures with knife edges at each arm of the specimen, is applied to the biaxial test. The obtained results indicate the decisive superiority of the optimized specimens for the proper performance on isotropic materials, as well as the paramount importance of the proposed off-axes testing technique for biaxial tests on anisotropic materials.
Experimental validation of a topology optimized acoustic cavity.
Christiansen, Rasmus E; Sigmund, Ole; Fernandez-Grande, Efren
2015-12-01
This paper presents the experimental validation of an acoustic cavity designed using topology optimization with the goal of minimizing the sound pressure locally for monochromatic excitation. The presented results show good agreement between simulations and measurements. The effect of damping, errors in the production of the cavity, and variations in operating frequency is discussed and the importance of taking these factors into account in the modeling process is highlighted. PMID:26723304
NASA Astrophysics Data System (ADS)
Zweibaum, Nicolas
The development of advanced nuclear reactor technology requires understanding of complex, integrated systems that exhibit novel phenomenology under normal and accident conditions. The advent of passive safety systems and enhanced modular construction methods requires the development and use of new frameworks to predict the behavior of advanced nuclear reactors, both from a safety standpoint and from an environmental impact perspective. This dissertation introduces such frameworks for scaling of integral effects tests for natural circulation in fluoride-salt-cooled, high-temperature reactors (FHRs) to validate evaluation models (EMs) for system behavior; subsequent reliability assessment of passive, natural- circulation-driven decay heat removal systems, using these validated models; evaluation of life cycle carbon dioxide emissions as a key environmental impact metric; and recommendations for further work to apply these frameworks in the development and optimization of advanced nuclear reactor designs. In this study, the developed frameworks are applied to the analysis of the Mark 1 pebble-bed FHR (Mk1 PB-FHR) under current investigation at the University of California, Berkeley (UCB). (Abstract shortened by UMI.).
Program Aids Analysis And Optimization Of Design
NASA Technical Reports Server (NTRS)
Rogers, James L., Jr.; Lamarsh, William J., II
1994-01-01
NETS/ PROSSS (NETS Coupled With Programming System for Structural Synthesis) computer program developed to provide system for combining NETS (MSC-21588), neural-network application program and CONMIN (Constrained Function Minimization, ARC-10836), optimization program. Enables user to reach nearly optimal design. Design then used as starting point in normal optimization process, possibly enabling user to converge to optimal solution in significantly fewer iterations. NEWT/PROSSS written in C language and FORTRAN 77.
Sequential experimental design based generalised ANOVA
NASA Astrophysics Data System (ADS)
Chakraborty, Souvik; Chowdhury, Rajib
2016-07-01
Over the last decade, surrogate modelling technique has gained wide popularity in the field of uncertainty quantification, optimization, model exploration and sensitivity analysis. This approach relies on experimental design to generate training points and regression/interpolation for generating the surrogate. In this work, it is argued that conventional experimental design may render a surrogate model inefficient. In order to address this issue, this paper presents a novel distribution adaptive sequential experimental design (DA-SED). The proposed DA-SED has been coupled with a variant of generalised analysis of variance (G-ANOVA), developed by representing the component function using the generalised polynomial chaos expansion. Moreover, generalised analytical expressions for calculating the first two statistical moments of the response, which are utilized in predicting the probability of failure, have also been developed. The proposed approach has been utilized in predicting probability of failure of three structural mechanics problems. It is observed that the proposed approach yields accurate and computationally efficient estimate of the failure probability.
Integrated multidisciplinary design optimization of rotorcraft
NASA Technical Reports Server (NTRS)
Adelman, Howard M.; Mantay, Wayne R.
1989-01-01
The NASA/Army research plan for developing the logic elements for helicopter rotor design optimization by integrating appropriate disciplines and accounting for important interactions among the disciplines is discussed. The paper describes the optimization formulation in terms of the objective function, design variables, and constraints. The analysis aspects are discussed, and an initial effort at defining the interdisciplinary coupling is summarized. Results are presented on the achievements made in the rotor aerodynamic performance optimization for minimum hover horsepower, rotor dynamic optimization for vibration reduction, rotor structural optimization for minimum weight, and integrated aerodynamic load/dynamics optimization for minimum vibration and weight.
Vehicle systems design optimization study
Gilmour, J. L.
1980-04-01
The optimization of an electric vehicle layout requires a weight distribution in the range of 53/47 to 62/38 in order to assure dynamic handling characteristics comparable to current production internal combustion engine vehicles. It is possible to achieve this goal and also provide passenger and cargo space comparable to a selected current production sub-compact car either in a unique new design or by utilizing the production vehicle as a base. Necessary modification of the base vehicle can be accomplished without major modification of the structure or running gear. As long as batteries are as heavy and require as much space as they currently do, they must be divided into two packages - one at front under the hood and a second at the rear under the cargo area - in order to achieve the desired weight distribution. The weight distribution criteria requires the placement of batteries at the front of the vehicle even when the central tunnel is used for the location of some batteries. The optimum layout has a front motor and front wheel drive. This configuration provides the optimum vehicle dynamic handling characteristics and the maximum passsenger and cargo space for a given size vehicle.
Comparison of optimal design methods in inverse problems
NASA Astrophysics Data System (ADS)
Banks, H. T.; Holm, K.; Kappel, F.
2011-07-01
Typical optimal design methods for inverse or parameter estimation problems are designed to choose optimal sampling distributions through minimization of a specific cost function related to the resulting error in parameter estimates. It is hoped that the inverse problem will produce parameter estimates with increased accuracy using data collected according to the optimal sampling distribution. Here we formulate the classical optimal design problem in the context of general optimization problems over distributions of sampling times. We present a new Prohorov metric-based theoretical framework that permits one to treat succinctly and rigorously any optimal design criteria based on the Fisher information matrix. A fundamental approximation theory is also included in this framework. A new optimal design, SE-optimal design (standard error optimal design), is then introduced in the context of this framework. We compare this new design criterion with the more traditional D-optimal and E-optimal designs. The optimal sampling distributions from each design are used to compute and compare standard errors; the standard errors for parameters are computed using asymptotic theory or bootstrapping and the optimal mesh. We use three examples to illustrate ideas: the Verhulst-Pearl logistic population model (Banks H T and Tran H T 2009 Mathematical and Experimental Modeling of Physical and Biological Processes (Boca Raton, FL: Chapman and Hall/CRC)), the standard harmonic oscillator model (Banks H T and Tran H T 2009) and a popular glucose regulation model (Bergman R N, Ider Y Z, Bowden C R and Cobelli C 1979 Am. J. Physiol. 236 E667-77 De Gaetano A and Arino O 2000 J. Math. Biol. 40 136-68 Toffolo G, Bergman R N, Finegood D T, Bowden C R and Cobelli C 1980 Diabetes 29 979-90).
Flat-plate photovoltaic array design optimization
NASA Technical Reports Server (NTRS)
Ross, R. G., Jr.
1980-01-01
An analysis is presented which integrates the results of specific studies in the areas of photovoltaic structural design optimization, optimization of array series/parallel circuit design, thermal design optimization, and optimization of environmental protection features. The analysis is based on minimizing the total photovoltaic system life-cycle energy cost including repair and replacement of failed cells and modules. This approach is shown to be a useful technique for array optimization, particularly when time-dependent parameters such as array degradation and maintenance are involved.
Design Optimization of Composite Structures under Uncertainty
NASA Technical Reports Server (NTRS)
Haftka, Raphael T.
2003-01-01
Design optimization under uncertainty is computationally expensive and is also challenging in terms of alternative formulation. The work under the grant focused on developing methods for design against uncertainty that are applicable to composite structural design with emphasis on response surface techniques. Applications included design of stiffened composite plates for improved damage tolerance, the use of response surfaces for fitting weights obtained by structural optimization, and simultaneous design of structure and inspection periods for fail-safe structures.
A Bayesian experimental design approach to structural health monitoring
Farrar, Charles; Flynn, Eric; Todd, Michael
2010-01-01
Optimal system design for SHM involves two primarily challenges. The first is the derivation of a proper performance function for a given system design. The second is the development of an efficient optimization algorithm for choosing a design that maximizes, or nearly maximizes the performance function. In this paper we will outline how an SHM practitioner can construct the proper performance function by casting the entire design problem into a framework of Bayesian experimental design. The approach demonstrates how the design problem necessarily ties together all steps of the SHM process.
Rationally reduced libraries for combinatorial pathway optimization minimizing experimental effort.
Jeschek, Markus; Gerngross, Daniel; Panke, Sven
2016-01-01
Rational flux design in metabolic engineering approaches remains difficult since important pathway information is frequently not available. Therefore empirical methods are applied that randomly change absolute and relative pathway enzyme levels and subsequently screen for variants with improved performance. However, screening is often limited on the analytical side, generating a strong incentive to construct small but smart libraries. Here we introduce RedLibs (Reduced Libraries), an algorithm that allows for the rational design of smart combinatorial libraries for pathway optimization thereby minimizing the use of experimental resources. We demonstrate the utility of RedLibs for the design of ribosome-binding site libraries by in silico and in vivo screening with fluorescent proteins and perform a simple two-step optimization of the product selectivity in the branched multistep pathway for violacein biosynthesis, indicating a general applicability for the algorithm and the proposed heuristics. We expect that RedLibs will substantially simplify the refactoring of synthetic metabolic pathways. PMID:27029461
Rationally reduced libraries for combinatorial pathway optimization minimizing experimental effort
Jeschek, Markus; Gerngross, Daniel; Panke, Sven
2016-01-01
Rational flux design in metabolic engineering approaches remains difficult since important pathway information is frequently not available. Therefore empirical methods are applied that randomly change absolute and relative pathway enzyme levels and subsequently screen for variants with improved performance. However, screening is often limited on the analytical side, generating a strong incentive to construct small but smart libraries. Here we introduce RedLibs (Reduced Libraries), an algorithm that allows for the rational design of smart combinatorial libraries for pathway optimization thereby minimizing the use of experimental resources. We demonstrate the utility of RedLibs for the design of ribosome-binding site libraries by in silico and in vivo screening with fluorescent proteins and perform a simple two-step optimization of the product selectivity in the branched multistep pathway for violacein biosynthesis, indicating a general applicability for the algorithm and the proposed heuristics. We expect that RedLibs will substantially simplify the refactoring of synthetic metabolic pathways. PMID:27029461
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.
Solar-Diesel Hybrid Power System Optimization and Experimental Validation
NASA Astrophysics Data System (ADS)
Jacobus, Headley Stewart
As of 2008 1.46 billion people, or 22 percent of the World's population, were without electricity. Many of these people live in remote areas where decentralized generation is the only method of electrification. Most mini-grids are powered by diesel generators, but new hybrid power systems are becoming a reliable method to incorporate renewable energy while also reducing total system cost. This thesis quantifies the measurable Operational Costs for an experimental hybrid power system in Sierra Leone. Two software programs, Hybrid2 and HOMER, are used during the system design and subsequent analysis. Experimental data from the installed system is used to validate the two programs and to quantify the savings created by each component within the hybrid system. This thesis bridges the gap between design optimization studies that frequently lack subsequent validation and experimental hybrid system performance studies.
Optimal pupil design for confocal microscopy
NASA Astrophysics Data System (ADS)
Patel, Yogesh G.; Rajadhyaksha, Milind; DiMarzio, Charles A.
2010-02-01
Confocal reflectance microscopy may enable screening and diagnosis of skin cancers noninvasively and in real-time, as an adjunct to biopsy and pathology. Current instruments are large, complex, and expensive. A simpler, confocal line-scanning microscope may accelerate the translation of confocal microscopy in clinical and surgical dermatology. A confocal reflectance microscope may use a beamsplitter, transmitting and detecting through the pupil, or a divided pupil, or theta configuration, with half used for transmission and half for detection. The divided pupil may offer better sectioning and contrast. We present a Fourier optics model and compare the on-axis irradiance of a confocal point-scanning microscope in both pupil configurations, optimizing the profile of a Gaussian beam in a circular or semicircular aperture. We repeat both calculations with a cylindrical lens which focuses the source to a line. The variable parameter is the fillfactor, h, the ratio of the 1/e2 diameter of the Gaussian beam to the diameter of the full aperture. The optimal values of h, for point scanning are 0.90 (full) and 0.66 for the half-aperture. For line-scanning, the fill-factors are 1.02 (full) and 0.52 (half). Additional parameters to consider are the optimal location of the point-source beam in the divided-pupil configuration, the optimal line width for the line-source, and the width of the aperture in the divided-pupil configuration. Additional figures of merit are field-of-view and sectioning. Use of optimal designs is critical in comparing the experimental performance of the different configurations.
Topology Optimization for Architected Materials Design
NASA Astrophysics Data System (ADS)
Osanov, Mikhail; Guest, James K.
2016-07-01
Advanced manufacturing processes provide a tremendous opportunity to fabricate materials with precisely defined architectures. To fully leverage these capabilities, however, materials architectures must be optimally designed according to the target application, base material used, and specifics of the fabrication process. Computational topology optimization offers a systematic, mathematically driven framework for navigating this new design challenge. The design problem is posed and solved formally as an optimization problem with unit cell and upscaling mechanics embedded within this formulation. This article briefly reviews the key requirements to apply topology optimization to materials architecture design and discusses several fundamental findings related to optimization of elastic, thermal, and fluidic properties in periodic materials. Emerging areas related to topology optimization for manufacturability and manufacturing variations, nonlinear mechanics, and multiscale design are also discussed.
Control design for the SERC experimental testbeds
NASA Technical Reports Server (NTRS)
Jacques, Robert; Blackwood, Gary; Macmartin, Douglas G.; How, Jonathan; Anderson, Eric
1992-01-01
Viewgraphs on control design for the Space Engineering Research Center experimental testbeds are presented. Topics covered include: SISO control design and results; sensor and actuator location; model identification; control design; experimental results; preliminary LAC experimental results; active vibration isolation problem statement; base flexibility coupling into isolation feedback loop; cantilever beam testbed; and closed loop results.
Design optimization of a portable, micro-hydrokinetic turbine
NASA Astrophysics Data System (ADS)
Schleicher, W. Chris
Marine and hydrokinetic (MHK) technology is a growing field that encompasses many different types of turbomachinery that operate on the kinetic energy of water. Micro hydrokinetics are a subset of MHK technology comprised of units designed to produce less than 100 kW of power. A propeller-type hydrokinetic turbine is investigated as a solution for a portable micro-hydrokinetic turbine with the needs of the United States Marine Corps in mind, as well as future commercial applications. This dissertation investigates using a response surface optimization methodology to create optimal turbine blade designs under many operating conditions. The field of hydrokinetics is introduced. The finite volume method is used to solve the Reynolds-Averaged Navier-Stokes equations with the k ω Shear Stress Transport model, for different propeller-type hydrokinetic turbines. The adaptive response surface optimization methodology is introduced as related to hydrokinetic turbines, and is benchmarked with complex algebraic functions. The optimization method is further studied to characterize the size of the experimental design on its ability to find optimum conditions. It was found that a large deviation between experimental design points was preferential. Different propeller hydrokinetic turbines were designed and compared with other forms of turbomachinery. It was found that the rapid simulations usually under predict performance compare to the refined simulations, and for some other designs it drastically over predicted performance. The optimization method was used to optimize a modular pump-turbine, verifying that the optimization work for other hydro turbine designs.
Integrated multidisciplinary design optimization of rotorcraft
NASA Technical Reports Server (NTRS)
Adelman, Howard M.; Mantay, Wayne R.
1989-01-01
The NASA/Army research plan for developing the logic elements for helicopter rotor design optimization by integrating appropriate disciplines and accounting for important interactions among the disciplines is discussed. The optimization formulation is described in terms of the objective function, design variables, and constraints. The analysis aspects are discussed, and an initial effort at defining the interdisciplinary coupling is summarized. Results are presented on the achievements made in the rotor dynamic optimization for vibration reduction, rotor structural optimization for minimum weight, and integrated aerodynamic load/dynamics optimization for minimum vibration and weight.
Optimal Designs of Staggered Dean Vortex Micromixers
Chen, Jyh Jian; Chen, Chun Huei; Shie, Shian Ruei
2011-01-01
A novel parallel laminar micromixer with a two-dimensional staggered Dean Vortex micromixer is optimized and fabricated in our study. Dean vortices induced by centrifugal forces in curved rectangular channels cause fluids to produce secondary flows. The split-and-recombination (SAR) structures of the flow channels and the impinging effects result in the reduction of the diffusion distance of two fluids. Three different designs of a curved channel micromixer are introduced to evaluate the mixing performance of the designed micromixer. Mixing performances are demonstrated by means of a pH indicator using an optical microscope and fluorescent particles via a confocal microscope at different flow rates corresponding to Reynolds numbers (Re) ranging from 0.5 to 50. The comparison between the experimental data and numerical results shows a very reasonable agreement. At a Re of 50, the mixing length at the sixth segment, corresponding to the downstream distance of 21.0 mm, can be achieved in a distance 4 times shorter than when the Re equals 1. An optimization of this micromixer is performed with two geometric parameters. These are the angle between the lines from the center to two intersections of two consecutive curved channels, θ, and the angle between two lines of the centers of three consecutive curved channels, ϕ. It can be found that the maximal mixing index is related to the maximal value of the sum of θ and ϕ, which is equal to 139.82°. PMID:21747691
Optimality of a Fully Stressed Design
NASA Technical Reports Server (NTRS)
Patnaik, Surya N.; Hopkins, Dale A.
1998-01-01
For a truss a fully stressed state is reached and when all its members are utilized to their full strength capacity. Historically, engineers considered such a design optimum. But recently this optimality has been questioned, especially since the weight of the structure is not explicitly used in fully stressed design calculations. This paper examines optimality of the full stressed design (FSD) with analytical and graphical illustrations. Solutions for a set of examples obtained by using the FSD method and optimization methods numerically confirm the optimality of the FSD. The FSD, which can be obtained with a small amount of calculation, can be extended to displacement constraints and to nontruss-type structures.
Design optimization studies using COSMIC NASTRAN
NASA Technical Reports Server (NTRS)
Pitrof, Stephen M.; Bharatram, G.; Venkayya, Vipperla B.
1993-01-01
The purpose of this study is to create, test and document a procedure to integrate mathematical optimization algorithms with COSMIC NASTRAN. This procedure is very important to structural design engineers who wish to capitalize on optimization methods to ensure that their design is optimized for its intended application. The OPTNAST computer program was created to link NASTRAN and design optimization codes into one package. This implementation was tested using two truss structure models and optimizing their designs for minimum weight, subject to multiple loading conditions and displacement and stress constraints. However, the process is generalized so that an engineer could design other types of elements by adding to or modifying some parts of the code.
Optimal multiobjective design of digital filters using spiral optimization technique.
Ouadi, Abderrahmane; Bentarzi, Hamid; Recioui, Abdelmadjid
2013-01-01
The multiobjective design of digital filters using spiral optimization technique is considered in this paper. This new optimization tool is a metaheuristic technique inspired by the dynamics of spirals. It is characterized by its robustness, immunity to local optima trapping, relative fast convergence and ease of implementation. The objectives of filter design include matching some desired frequency response while having minimum linear phase; hence, reducing the time response. The results demonstrate that the proposed problem solving approach blended with the use of the spiral optimization technique produced filters which fulfill the desired characteristics and are of practical use. PMID:24083108
Web-based tools for finding optimal designs in biomedical studies
Wong, Weng Kee
2013-01-01
Experimental costs are rising and applications of optimal design ideas are increasingly applied in many disciplines. However, the theory for constructing optimal designs can be esoteric and its implementation can be difficult. To help practitioners have easier access to optimal designs and better appreciate design issues, we present a web site at http://optimal-design.biostat.ucla.edu/optimal/ capable of generating different types of tailor-made optimal designs for popular models in the biological sciences. This site also evaluates various efficiencies of a user-specified design and so enables practitioners to appreciate robustness properties of the design before implementation. PMID:23806678
Optimization, an Important Stage of Engineering Design
ERIC Educational Resources Information Center
Kelley, Todd R.
2010-01-01
A number of leaders in technology education have indicated that a major difference between the technological design process and the engineering design process is analysis and optimization. The analysis stage of the engineering design process is when mathematical models and scientific principles are employed to help the designer predict design…
Computational design optimization for microfluidic magnetophoresis
Plouffe, Brian D.; Lewis, Laura H.; Murthy, Shashi K.
2011-01-01
Current macro- and microfluidic approaches for the isolation of mammalian cells are limited in both efficiency and purity. In order to design a robust platform for the enumeration of a target cell population, high collection efficiencies are required. Additionally, the ability to isolate pure populations with minimal biological perturbation and efficient off-chip recovery will enable subcellular analyses of these cells for applications in personalized medicine. Here, a rational design approach for a simple and efficient device that isolates target cell populations via magnetic tagging is presented. In this work, two magnetophoretic microfluidic device designs are described, with optimized dimensions and operating conditions determined from a force balance equation that considers two dominant and opposing driving forces exerted on a magnetic-particle-tagged cell, namely, magnetic and viscous drag. Quantitative design criteria for an electromagnetic field displacement-based approach are presented, wherein target cells labeled with commercial magnetic microparticles flowing in a central sample stream are shifted laterally into a collection stream. Furthermore, the final device design is constrained to fit on standard rectangular glass coverslip (60 (L)×24 (W)×0.15 (H) mm3) to accommodate small sample volume and point-of-care design considerations. The anticipated performance of the device is examined via a parametric analysis of several key variables within the model. It is observed that minimal currents (<500 mA) are required to generate magnetic fields sufficient to separate cells from the sample streams flowing at rate as high as 7 ml∕h, comparable to the performance of current state-of-the-art magnet-activated cell sorting systems currently used in clinical settings. Experimental validation of the presented model illustrates that a device designed according to the derived rational optimization can effectively isolate (∼100%) a magnetic-particle-tagged cell
Computational design optimization for microfluidic magnetophoresis.
Plouffe, Brian D; Lewis, Laura H; Murthy, Shashi K
2011-01-01
Current macro- and microfluidic approaches for the isolation of mammalian cells are limited in both efficiency and purity. In order to design a robust platform for the enumeration of a target cell population, high collection efficiencies are required. Additionally, the ability to isolate pure populations with minimal biological perturbation and efficient off-chip recovery will enable subcellular analyses of these cells for applications in personalized medicine. Here, a rational design approach for a simple and efficient device that isolates target cell populations via magnetic tagging is presented. In this work, two magnetophoretic microfluidic device designs are described, with optimized dimensions and operating conditions determined from a force balance equation that considers two dominant and opposing driving forces exerted on a magnetic-particle-tagged cell, namely, magnetic and viscous drag. Quantitative design criteria for an electromagnetic field displacement-based approach are presented, wherein target cells labeled with commercial magnetic microparticles flowing in a central sample stream are shifted laterally into a collection stream. Furthermore, the final device design is constrained to fit on standard rectangular glass coverslip (60 (L)×24 (W)×0.15 (H) mm(3)) to accommodate small sample volume and point-of-care design considerations. The anticipated performance of the device is examined via a parametric analysis of several key variables within the model. It is observed that minimal currents (<500 mA) are required to generate magnetic fields sufficient to separate cells from the sample streams flowing at rate as high as 7 ml∕h, comparable to the performance of current state-of-the-art magnet-activated cell sorting systems currently used in clinical settings. Experimental validation of the presented model illustrates that a device designed according to the derived rational optimization can effectively isolate (∼100%) a magnetic-particle-tagged cell
Singularities in Optimal Structural Design
NASA Technical Reports Server (NTRS)
Patnaik, S. N.; Guptill, J. D.; Berke, L.
1992-01-01
Singularity conditions that arise during structural optimization can seriously degrade the performance of the optimizer. The singularities are intrinsic to the formulation of the structural optimization problem and are not associated with the method of analysis. Certain conditions that give rise to singularities have been identified in earlier papers, encompassing the entire structure. Further examination revealed more complex sets of conditions in which singularities occur. Some of these singularities are local in nature, being associated with only a segment of the structure. Moreover, the likelihood that one of these local singularities may arise during an optimization procedure can be much greater than that of the global singularity identified earlier. Examples are provided of these additional forms of singularities. A framework is also given in which these singularities can be recognized. In particular, the singularities can be identified by examination of the stress displacement relations along with the compatibility conditions and/or the displacement stress relations derived in the integrated force method of structural analysis.
Singularities in optimal structural design
NASA Technical Reports Server (NTRS)
Patnaik, S. N.; Guptill, J. D.; Berke, L.
1992-01-01
Singularity conditions that arise during structural optimization can seriously degrade the performance of the optimizer. The singularities are intrinsic to the formulation of the structural optimization problem and are not associated with the method of analysis. Certain conditions that give rise to singularities have been identified in earlier papers, encompassing the entire structure. Further examination revealed more complex sets of conditions in which singularities occur. Some of these singularities are local in nature, being associated with only a segment of the structure. Moreover, the likelihood that one of these local singularities may arise during an optimization procedure can be much greater than that of the global singularity identified earlier. Examples are provided of these additional forms of singularities. A framework is also given in which these singularities can be recognized. In particular, the singularities can be identified by examination of the stress displacement relations along with the compatibility conditions and/or the displacement stress relations derived in the integrated force method of structural analysis.
Multidisciplinary Optimization Methods for Aircraft Preliminary Design
NASA Technical Reports Server (NTRS)
Kroo, Ilan; Altus, Steve; Braun, Robert; Gage, Peter; Sobieski, Ian
1994-01-01
This paper describes a research program aimed at improved methods for multidisciplinary design and optimization of large-scale aeronautical systems. The research involves new approaches to system decomposition, interdisciplinary communication, and methods of exploiting coarse-grained parallelism for analysis and optimization. A new architecture, that involves a tight coupling between optimization and analysis, is intended to improve efficiency while simplifying the structure of multidisciplinary, computation-intensive design problems involving many analysis disciplines and perhaps hundreds of design variables. Work in two areas is described here: system decomposition using compatibility constraints to simplify the analysis structure and take advantage of coarse-grained parallelism; and collaborative optimization, a decomposition of the optimization process to permit parallel design and to simplify interdisciplinary communication requirements.
Magnetic design optimization using variable metrics
Davey, K.R.
1995-11-01
The optimal design of a magnet assembly for a magnetic levitated train is approached using a three step process. First, the key parameters within the objective performance index are computed for the variation range of the problem. Second, the performance index is fitted to a smooth polynomial involving products of the powers of all variables. Third, a constrained optimization algorithm is employed to predict the optimal choice of the variables. An assessment of the integrity of the optimization program is obtained by comparing the final optimized solution with that predicted by the field analysis in the final configuration. Additional field analysis is recommended around the final solution to fine tune the solution.
Cold Climates Heat Pump Design Optimization
Abdelaziz, Omar; Shen, Bo
2012-01-01
Heat pumps provide an efficient heating method; however they suffer from sever capacity and performance degradation at low ambient conditions. This has deterred market penetration in cold climates. There is a continuing effort to find an efficient air source cold climate heat pump that maintains acceptable capacity and performance at low ambient conditions. Systematic optimization techniques provide a reliable approach for the design of such systems. This paper presents a step-by-step approach for the design optimization of cold climate heat pumps. We first start by describing the optimization problem: objective function, constraints, and design space. Then we illustrate how to perform this design optimization using an open source publically available optimization toolbox. The response of the heat pump design was evaluated using a validated component based vapor compression model. This model was treated as a black box model within the optimization framework. Optimum designs for different system configurations are presented. These optimum results were further analyzed to understand the performance tradeoff and selection criteria. The paper ends with a discussion on the use of systematic optimization for the cold climate heat pump design.
Exponential approximations in optimal design
NASA Technical Reports Server (NTRS)
Belegundu, A. D.; Rajan, S. D.; Rajgopal, J.
1990-01-01
One-point and two-point exponential functions have been developed and proved to be very effective approximations of structural response. The exponential has been compared to the linear, reciprocal and quadratic fit methods. Four test problems in structural analysis have been selected. The use of such approximations is attractive in structural optimization to reduce the numbers of exact analyses which involve computationally expensive finite element analysis.
Optimization criteria for SRAM design: lithography contribution
NASA Astrophysics Data System (ADS)
Cole, Daniel C.; Bula, Orest; Conrad, Edward W.; Coops, Daniel S.; Leipold, William C.; Mann, Randy W.; Oppold, Jeffrey H.
1999-07-01
Here we discuss the use of well calibrated resist and etch bias models, in conjunction with a fast microlithography aerial image simulator, to predict and 'optimize' the printed shapes through all critical levels in a dense SRAM design. Our key emphasis here is on 'optimization criteria', namely, having achieved good predictability for printability with lithography models, how to use this capability in conjunction of best electrical performance, yield, and density. The key lithography/design optimization issues discussed here are: (1) tightening of gate width variation by reducing spatial curvature in the source and drain regions, (2) achieving sufficient contact areas, (3) maximizing process window for overlay, (4) reducing leakage mechanisms by reducing contributions of stress and strain due to the printed shape of oxide isolation regions, (5) examining topological differences in design during the optimization process, (6) accounting for mask corner rounding, and (7) designing for scalability to smaller dimensions to achieve optical design reusability issues without hardware.
Herrero, A; Ortiz, M C; Sarabia, L A
2013-05-01
The determination of triazines in oranges using a GC-MS system coupled to a programmed temperature vaporizer (PTV) inlet in the context of legislation is performed. Both pretreatment (using a Quick Easy Cheap Effective Rugged and Safe (QuEChERS) procedure) and injection steps are optimized using D-optimal experimental designs for reducing the experimental effort. The relative dirty extracts obtained and the elution time shifts make it necessary to use a PARAFAC2 decomposition to solve these two usual problems in the chromatographic determinations. The "second-order advantage" of the PARAFAC2 decomposition allows unequivocal identification according to document SANCO/12495/2011 (taking into account the tolerances for relative retention time and the relative abundance for the diagnostic ions), avoiding false negatives even in the presence of unknown co-eluents. The detection limits (CCα) found, from 0.51 to 1.05μgkg(-1), are far below the maximum residue levels (MRLs) established by the European Union for simazine, atrazine, terbuthylazine, ametryn, simetryn, prometryn and terbutryn in oranges. No MRL violations were found in the commercial oranges analyzed. PMID:23522618
Optimization design of electromagnetic shielding composites
NASA Astrophysics Data System (ADS)
Qu, Zhaoming; Wang, Qingguo; Qin, Siliang; Hu, Xiaofeng
2013-03-01
The effective electromagnetic parameters physical model of composites and prediction formulas of composites' shielding effectiveness and reflectivity were derived based on micromechanics, variational principle and electromagnetic wave transmission theory. The multi-objective optimization design of multilayer composites was carried out using genetic algorithm. The optimized results indicate that material parameter proportioning of biggest absorption ability can be acquired under the condition of the minimum shielding effectiveness can be satisfied in certain frequency band. The validity of optimization design model was verified and the scheme has certain theoretical value and directive significance to the design of high efficiency shielding composites.
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.
Optimization methods applied to hybrid vehicle design
NASA Technical Reports Server (NTRS)
Donoghue, J. F.; Burghart, J. H.
1983-01-01
The use of optimization methods as an effective design tool in the design of hybrid vehicle propulsion systems is demonstrated. Optimization techniques were used to select values for three design parameters (battery weight, heat engine power rating and power split between the two on-board energy sources) such that various measures of vehicle performance (acquisition cost, life cycle cost and petroleum consumption) were optimized. The apporach produced designs which were often significant improvements over hybrid designs already reported on in the literature. The principal conclusions are as follows. First, it was found that the strategy used to split the required power between the two on-board energy sources can have a significant effect on life cycle cost and petroleum consumption. Second, the optimization program should be constructed so that performance measures and design variables can be easily changed. Third, the vehicle simulation program has a significant effect on the computer run time of the overall optimization program; run time can be significantly reduced by proper design of the types of trips the vehicle takes in a one year period. Fourth, care must be taken in designing the cost and constraint expressions which are used in the optimization so that they are relatively smooth functions of the design variables. Fifth, proper handling of constraints on battery weight and heat engine rating, variables which must be large enough to meet power demands, is particularly important for the success of an optimization study. Finally, the principal conclusion is that optimization methods provide a practical tool for carrying out the design of a hybrid vehicle propulsion system.
Design Optimization Programmable Calculators versus Campus Computers.
ERIC Educational Resources Information Center
Savage, Michael
1982-01-01
A hypothetical design optimization problem and technical information on the three design parameters are presented. Although this nested iteration problem can be solved on a computer (flow diagram provided), this article suggests that several hand held calculators can be used to perform the same design iteration. (SK)
Optimality criteria solution strategies in multiple constraint design optimization
NASA Technical Reports Server (NTRS)
Levy, R.; Parzynski, W.
1981-01-01
Procedures and solution strategies are described to solve the conventional structural optimization problem using the Lagrange multiplier technique. The multipliers, obtained through solution of an auxiliary nonlinear optimization problem, lead to optimality criteria to determine the design variables. It is shown that this procedure is essentially equivalent to an alternative formulation using a dual method Lagrangian function objective. Although mathematical formulations are straight-forward, successful applications and computational efficiency depend upon execution procedure strategies. Strategies examined, with application examples, include selection of active constraints, move limits, line search procedures, and side constraint boundaries.
Interaction Prediction Optimization in Multidisciplinary Design Optimization Problems
Zhang, Xiaoling; Huang, Hong-Zhong; Wang, Zhonglai; Xu, Huanwei
2014-01-01
The distributed strategy of Collaborative Optimization (CO) is suitable for large-scale engineering systems. However, it is hard for CO to converge when there is a high level coupled dimension. Furthermore, the discipline objectives cannot be considered in each discipline optimization problem. In this paper, one large-scale systems control strategy, the interaction prediction method (IPM), is introduced to enhance CO. IPM is utilized for controlling subsystems and coordinating the produce process in large-scale systems originally. We combine the strategy of IPM with CO and propose the Interaction Prediction Optimization (IPO) method to solve MDO problems. As a hierarchical strategy, there are a system level and a subsystem level in IPO. The interaction design variables (including shared design variables and linking design variables) are operated at the system level and assigned to the subsystem level as design parameters. Each discipline objective is considered and optimized at the subsystem level simultaneously. The values of design variables are transported between system level and subsystem level. The compatibility constraints are replaced with the enhanced compatibility constraints to reduce the dimension of design variables in compatibility constraints. Two examples are presented to show the potential application of IPO for MDO. PMID:24744685
DESIGN AND OPTIMIZATION OF A REFRIGERATION SYSTEM
The paper discusses the design and optimization of a refrigeration system, using a mathematical model of a refrigeration system modified to allow its use with the optimization program. he model was developed using only algebraic equations so that it could be used with the optimiz...
Turbomachinery Airfoil Design Optimization Using Differential Evolution
NASA Technical Reports Server (NTRS)
Madavan, Nateri K.; Biegel, Bryan (Technical Monitor)
2002-01-01
An aerodynamic design optimization procedure that is based on a evolutionary algorithm known at Differential Evolution is described. Differential Evolution is a simple, fast, and robust evolutionary strategy that has been proven effective in determining the global optimum for several difficult optimization problems, including highly nonlinear systems with discontinuities and multiple local optima. The method is combined with a Navier-Stokes solver that evaluates the various intermediate designs and provides inputs to the optimization procedure. An efficient constraint handling mechanism is also incorporated. Results are presented for the inverse design of a turbine airfoil from a modern jet engine and compared to earlier methods. The capability of the method to search large design spaces and obtain the optimal airfoils in an automatic fashion is demonstrated. Substantial reductions in the overall computing time requirements are achieved by using the algorithm in conjunction with neural networks.
Turbomachinery Airfoil Design Optimization Using Differential Evolution
NASA Technical Reports Server (NTRS)
Madavan, Nateri K.; Biegel, Bryan A. (Technical Monitor)
2002-01-01
An aerodynamic design optimization procedure that is based on a evolutionary algorithm known at Differential Evolution is described. Differential Evolution is a simple, fast, and robust evolutionary strategy that has been proven effective in determining the global optimum for several difficult optimization problems, including highly nonlinear systems with discontinuities and multiple local optima. The method is combined with a Navier-Stokes solver that evaluates the various intermediate designs and provides inputs to the optimization procedure. An efficient constraint handling mechanism is also incorporated. Results are presented for the inverse design of a turbine airfoil from a modern jet engine. The capability of the method to search large design spaces and obtain the optimal airfoils in an automatic fashion is demonstrated. Substantial reductions in the overall computing time requirements are achieved by using the algorithm in conjunction with neural networks.
Experimental design for improved ceramic processing, emphasizing the Taguchi Method
Weiser, M.W. . Mechanical Engineering Dept.); Fong, K.B. )
1993-12-01
Ceramic processing often requires substantial experimentation to produce acceptable product quality and performance. This is a consequence of ceramic processes depending upon a multitude of factors, some of which can be controlled and others that are beyond the control of the manufacturer. Statistical design of experiments is a procedure that allows quick, economical, and accurate evaluation of processes and products that depend upon several variables. Designed experiments are sets of tests in which the variables are adjusted methodically. A well-designed experiment yields unambiguous results at minimal cost. A poorly designed experiment may reveal little information of value even with complex analysis, wasting valuable time and resources. This article will review the most common experimental designs. This will include both nonstatistical designs and the much more powerful statistical experimental designs. The Taguchi Method developed by Grenichi Taguchi will be discussed in some detail. The Taguchi method, based upon fractional factorial experiments, is a powerful tool for optimizing product and process performance.
Optimal design of artificial reefs for sturgeon
NASA Astrophysics Data System (ADS)
Yarbrough, Cody; Cotel, Aline; Kleinheksel, Abby
2015-11-01
The Detroit River, part of a busy corridor between Lakes Huron and Erie, was extensively modified to create deep shipping channels, resulting in a loss of spawning habitat for lake sturgeon and other native fish (Caswell et al. 2004, Bennion and Manny 2011). Under the U.S.- Canada Great Lakes Water Quality Agreement, there are remediation plans to construct fish spawning reefs to help with historic habitat losses and degraded fish populations, specifically sturgeon. To determine optimal reef design, experimental work has been undertaken. Different sizes and shapes of reefs are tested for a given set of physical conditions, such as flow depth and flow velocity, matching the relevant dimensionless parameters dominating the flow physics. The physical conditions are matched with the natural conditions encountered in the Detroit River. Using Particle Image Velocimetry, Acoustic Doppler Velocimetry and dye studies, flow structures, vorticity and velocity gradients at selected locations have been identified and quantified to allow comparison with field observations and numerical model results. Preliminary results are helping identify the design features to be implemented in the next phase of reef construction. Sponsored by NOAA.
A More Rigorous Quasi-Experimental Alternative to the One-Group Pretest-Posttest Design.
ERIC Educational Resources Information Center
Johnson, Craig W.
1986-01-01
A simple quasi-experimental design is described which may have utility in a variety of applied and laboratory research settings where ordinarily the one-group pretest-posttest pre-experimental design might otherwise be the procedure of choice. The design approaches the internal validity of true experimental designs while optimizing external…
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
Quasi experimental designs in pharmacist intervention research.
Krass, Ines
2016-06-01
Background In the field of pharmacist intervention research it is often difficult to conform to the rigorous requirements of the "true experimental" models, especially the requirement of randomization. When randomization is not feasible, a practice based researcher can choose from a range of "quasi-experimental designs" i.e., non-randomised and at time non controlled. Objective The aim of this article was to provide an overview of quasi-experimental designs, discuss their strengths and weaknesses and to investigate their application in pharmacist intervention research over the previous decade. Results In the literature quasi experimental studies may be classified into five broad categories: quasi-experimental design without control groups; quasi-experimental design that use control groups with no pre-test; quasi-experimental design that use control groups and pre-tests; interrupted time series and stepped wedge designs. Quasi-experimental study design has consistently featured in the evolution of pharmacist intervention research. The most commonly applied of all quasi experimental designs in the practice based research literature are the one group pre-post-test design and the non-equivalent control group design i.e., (untreated control group with dependent pre-tests and post-tests) and have been used to test the impact of pharmacist interventions in general medications management as well as in specific disease states. Conclusion Quasi experimental studies have a role to play as proof of concept, in the pilot phases of interventions when testing different intervention components, especially in complex interventions. They serve to develop an understanding of possible intervention effects: while in isolation they yield weak evidence of clinical efficacy, taken collectively, they help build a body of evidence in support of the value of pharmacist interventions across different practice settings and countries. However, when a traditional RCT is not feasible for
Three-mirror telescopes: design and optimization.
Robb, P N
1978-09-01
A set of equations is developed which yields the constructional parameters of three-mirror all-reflecting optical systems. An equation whose factors allow the shape of the image surface to be controlled is also derived. A method of optimizing the performance of three-mirror systems by varying the inputs to the design equations is described, and the results are compared with those obtained through a conventional numerical design optimization. The technique described is shown to be markedly superior to the usual optimization method of varying the constructional parameters of the system. PMID:20203850
GCFR shielding design and supporting experimental programs
Perkins, R.G.; Hamilton, C.J.; Bartine, D.
1980-05-01
The shielding for the conceptual design of the gas-cooled fast breeder reactor (GCFR) is described, and the component exposure design criteria which determine the shield design are presented. The experimental programs for validating the GCFR shielding design methods and data (which have been in existence since 1976) are also discussed.
Optimal design of reverse osmosis module networks
Maskan, F.; Wiley, D.E.; Johnston, L.P.M.; Clements, D.J.
2000-05-01
The structure of individual reverse osmosis modules, the configuration of the module network, and the operating conditions were optimized for seawater and brackish water desalination. The system model included simple mathematical equations to predict the performance of the reverse osmosis modules. The optimization problem was formulated as a constrained multivariable nonlinear optimization. The objective function was the annual profit for the system, consisting of the profit obtained from the permeate, capital cost for the process units, and operating costs associated with energy consumption and maintenance. Optimization of several dual-stage reverse osmosis systems were investigated and compared. It was found that optimal network designs are the ones that produce the most permeate. It may be possible to achieve economic improvements by refining current membrane module designs and their operating pressures.
Vehicle systems design optimization study
NASA Technical Reports Server (NTRS)
Gilmour, J. L.
1980-01-01
The optimum vehicle configuration and component locations are determined for an electric drive vehicle based on using the basic structure of a current production subcompact vehicle. The optimization of an electric vehicle layout requires a weight distribution in the range of 53/47 to 62/38 in order to assure dynamic handling characteristics comparable to current internal combustion engine vehicles. Necessary modification of the base vehicle can be accomplished without major modification of the structure or running gear. As long as batteries are as heavy and require as much space as they currently do, they must be divided into two packages, one at front under the hood and a second at the rear under the cargo area, in order to achieve the desired weight distribution. The weight distribution criteria requires the placement of batteries at the front of the vehicle even when the central tunnel is used for the location of some batteries. The optimum layout has a front motor and front wheel drive. This configuration provides the optimum vehicle dynamic handling characteristics and the maximum passenger and cargo space for a given size vehicle.
Optimal needle design for minimal insertion force and bevel length.
Wang, Yancheng; Chen, Roland K; Tai, Bruce L; McLaughlin, Patrick W; Shih, Albert J
2014-09-01
This research presents a methodology for optimal design of the needle geometry to minimize the insertion force and bevel length based on mathematical models of cutting edge inclination and rake angles and the insertion force. In brachytherapy, the needle with lower insertion force typically is easier for guidance and has less deflection. In this study, the needle with lancet point (denoted as lancet needle) is applied to demonstrate the model-based optimization for needle design. Mathematical models to calculate the bevel length and inclination and rake angles for lancet needle are presented. A needle insertion force model is developed to predict the insertion force for lancet needle. The genetic algorithm is utilized to optimize the needle geometry for two cases. One is to minimize the needle insertion force. Using the geometry of a commercial lancet needle as the baseline, the optimized needle has 11% lower insertion force with the same bevel length. The other case is to minimize the bevel length under the same needle insertion force. The optimized design can reduce the bevel length by 46%. Both optimized needle designs were validated experimentally in ex vivo porcine liver needle insertion tests and demonstrated the methodology of the model-based optimal needle design. PMID:24957487
Torsional ultrasonic transducer computational design optimization.
Melchor, J; Rus, G
2014-09-01
A torsional piezoelectric ultrasonic sensor design is proposed in this paper and computationally tested and optimized to measure shear stiffness properties of soft tissue. These are correlated with a number of pathologies like tumors, hepatic lesions and others. The reason is that, whereas compressibility is predominantly governed by the fluid phase of the tissue, the shear stiffness is dependent on the stroma micro-architecture, which is directly affected by those pathologies. However, diagnostic tools to quantify them are currently not well developed. The first contribution is a new typology of design adapted to quasifluids. A second contribution is the procedure for design optimization, for which an analytical estimate of the Robust Probability Of Detection, called RPOD, is presented for use as optimality criteria. The RPOD is formulated probabilistically to maximize the probability of detecting the least possible pathology while minimizing the effect of noise. The resulting optimal transducer has a resonance frequency of 28 kHz. PMID:24882020
Design optimization for active twist rotor blades
NASA Astrophysics Data System (ADS)
Mok, Ji Won
This dissertation introduces the process of optimizing active twist rotor blades in the presence of embedded anisotropic piezo-composite actuators. Optimum design of active twist blades is a complex task, since it involves a rich design space with tightly coupled design variables. The study presents the development of an optimization framework for active helicopter rotor blade cross-sectional design. This optimization framework allows for exploring a rich and highly nonlinear design space in order to optimize the active twist rotor blades. Different analytical components are combined in the framework: cross-sectional analysis (UM/VABS), an automated mesh generator, a beam solver (DYMORE), a three-dimensional local strain recovery module, and a gradient based optimizer within MATLAB. Through the mathematical optimization problem, the static twist actuation performance of a blade is maximized while satisfying a series of blade constraints. These constraints are associated with locations of the center of gravity and elastic axis, blade mass per unit span, fundamental rotating blade frequencies, and the blade strength based on local three-dimensional strain fields under worst loading conditions. Through pre-processing, limitations of the proposed process have been studied. When limitations were detected, resolution strategies were proposed. These include mesh overlapping, element distortion, trailing edge tab modeling, electrode modeling and foam implementation of the mesh generator, and the initial point sensibility of the current optimization scheme. Examples demonstrate the effectiveness of this process. Optimization studies were performed on the NASA/Army/MIT ATR blade case. Even though that design was built and shown significant impact in vibration reduction, the proposed optimization process showed that the design could be improved significantly. The second example, based on a model scale of the AH-64D Apache blade, emphasized the capability of this framework to
OSHA and Experimental Safety Design.
ERIC Educational Resources Information Center
Sichak, Stephen, Jr.
1983-01-01
Suggests that a governmental agency, most likely Occupational Safety and Health Administration (OSHA) be considered in the safety design stage of any experiment. Focusing on OSHA's role, discusses such topics as occupational health hazards of toxic chemicals in laboratories, occupational exposure to benzene, and role/regulations of other agencies.…
Acoustic control in enclosures using optimally designed Helmholtz resonators
NASA Astrophysics Data System (ADS)
Driesch, Patricia Lynne
A virtual design methodology is developed to minimize the noise in enclosures with optimally designed, passive, acoustic absorbers (Helmholtz resonators). A series expansion of eigen functions is used to represent the acoustic absorbers as external volume velocities, eliminating the need for a solution of large matrix eigen value problems. A determination of this type (efficient model/reevaluation approach) significantly increases the design possibilities when optimization techniques are implemented. As a benchmarking exercise, this novel methodology was experimentally validated for a narrowband acoustic assessment of two optimally designed Helmholtz resonators coupled to a 2D enclosure. The resonators were tuned to the two lowest resonance frequencies of a 30.5 by 40.6 by 2.5 cm (12 x 16 x 1 inch) cavity with the resonator volume occupying only 2% of the enclosure volume. A maximum potential energy reduction of 12.4 dB was obtained at the second resonance of the cavity. As a full-scale demonstration of the efficacy of the proposed design method, the acoustic response from 90--190 Hz of a John Deere 7000 Ten series tractor cabin was investigated. The lowest cabin mode, referred to as a "boom" mode, proposes a significant challenge to a noise control engineer since its anti-node is located near the head of the operator and often generates unacceptable sound pressure levels. Exploiting the low frequency capability of Helmholtz resonators, lumped parameter models of these resonators were coupled to the enclosure via an experimentally determined acoustic model of the tractor cabin. The virtual design methodology uses gradient optimization techniques as a post processor for the modeling and analysis of the unmodified acoustic interior to determine optimal resonator characteristics. Using two optimally designed Helmholtz resonators; potential energy was experimentally reduced by 3.4 and 10.3 dB at 117 and 167 Hz, respectively.