NASA Astrophysics Data System (ADS)
Takemiya, Tetsushi
, and that (2) the AMF terminates optimization erroneously when the optimization problems have constraints. The first problem is due to inaccuracy in computing derivatives in the AMF, and the second problem is due to erroneous treatment of the trust region ratio, which sets the size of the domain for an optimization in the AMF. In order to solve the first problem of the AMF, automatic differentiation (AD) technique, which reads the codes of analysis models and automatically generates new derivative codes based on some mathematical rules, is applied. If derivatives are computed with the generated derivative code, they are analytical, and the required computational time is independent of the number of design variables, which is very advantageous for realistic aerospace engineering problems. However, if analysis models implement iterative computations such as computational fluid dynamics (CFD), which solves system partial differential equations iteratively, computing derivatives through the AD requires a massive memory size. The author solved this deficiency by modifying the AD approach and developing a more efficient implementation with CFD, and successfully applied the AD to general CFD software. In order to solve the second problem of the AMF, the governing equation of the trust region ratio, which is very strict against the violation of constraints, is modified so that it can accept the violation of constraints within some tolerance. By accepting violations of constraints during the optimization process, the AMF can continue optimization without terminating immaturely and eventually find the true optimum design point. With these modifications, the AMF is referred to as "Robust AMF," and it is applied to airfoil and wing aerodynamic design problems using Euler CFD software. The former problem has 21 design variables, and the latter 64. In both problems, derivatives computed with the proposed AD method are first compared with those computed with the finite
Experimental Investigation on Adaptive Robust Controller Designs Applied to Constrained Manipulators
Nogueira, Samuel L.; Pazelli, Tatiana F. P. A. T.; Siqueira, Adriano A. G.; Terra, Marco H.
2013-01-01
In this paper, two interlaced studies are presented. The first is directed to the design and construction of a dynamic 3D force/moment sensor. The device is applied to provide a feedback signal of forces and moments exerted by the robotic end-effector. This development has become an alternative solution to the existing multi-axis load cell based on static force and moment sensors. The second one shows an experimental investigation on the performance of four different adaptive nonlinear ℋ∞ control methods applied to a constrained manipulator subject to uncertainties in the model and external disturbances. Coordinated position and force control is evaluated. Adaptive procedures are based on neural networks and fuzzy systems applied in two different modeling strategies. The first modeling strategy requires a well-known nominal model for the robot, so that the intelligent systems are applied only to estimate the effects of uncertainties, unmodeled dynamics and external disturbances. The second strategy considers that the robot model is completely unknown and, therefore, intelligent systems are used to estimate these dynamics. A comparative study is conducted based on experimental implementations performed with an actual planar manipulator and with the dynamic force sensor developed for this purpose. PMID:23598503
A robust nonlinear skid-steering control design applied to the MULE (6x6) unmanned ground vehicle
NASA Astrophysics Data System (ADS)
Kaloust, Joseph
2006-05-01
The paper presents a robust nonlinear skid-steering control design concept. The control concept is based on the recursive/backstepping control design technique and is capable of compensating for uncertainties associated with sensor noise measurements and/or system dynamic state uncertainties. The objective of this control design is to demonstrate the performance of the nonlinear controller under uncertainty associate with road traction (rough off-road and on-road terrain). The MULE vehicle is used in the simulation modeling and results.
Robustness analysis applied to substructure controller synthesis
NASA Technical Reports Server (NTRS)
Gonzalez-Oberdoerffer, Marcelo F.; Craig, Roy R., Jr.
1993-01-01
The stability and robustness of the controlled system obtained via the substructure control synthesis (SCS) method of Su et al. (1990) were examined using a six-bay truss model, and employing an LQG control design method to obtain controllers for two separate structures. It is found that the assembled controller provides a stability in this instance. A qualitative assessment of the stability robustness of the system with controller designed with the SCS method is provided by obtaining a controller using the complete truss model and comparing the robustness of the corresponding closed-loop systems.
Robust design of dynamic observers
NASA Technical Reports Server (NTRS)
Bhattacharyya, S. P.
1974-01-01
The two (identity) observer realizations z = Mz + Ky and z = transpose of Az + transpose of K(y - transpose of Cz), respectively called the open loop and closed loop realizations, for the linear system x = Ax, y = Cx are analyzed with respect to the requirement of robustness; i.e., the requirement that the observer continue to regulate the error x - z satisfactorily despite small variations in the observer parameters from the projected design values. The results show that the open loop realization is never robust, that robustness requires a closed loop implementation, and that the closed loop realization is robust with respect to small perturbations in the gains transpose of K if and only if the observer can be built to contain an exact replica of the unstable and underdamped dynamics of the system being observed. These results clarify the stringent accuracy requirements on both models and hardware that must be met before an observer can be considered for use in a control system.
Applying robust multibit watermarks to digital images
NASA Astrophysics Data System (ADS)
Tsolis, Dimitrios; Nikolopoulos, Spiridon; Drossos, Lambros; Sioutas, Spyros; Papatheodorou, Theodore
2009-05-01
The current work is focusing on the implementation of a robust multibit watermarking algorithm for digital images, which is based on an innovative spread spectrum technique analysis. The paper presents the watermark embedding and detection algorithms, which use both wavelets and the Discrete Cosine Transform and analyzes the arising issues.
Robust multivariable controller design for flexible spacecraft
NASA Technical Reports Server (NTRS)
Joshi, Suresh M.; Armstrong, Ernest S.
1986-01-01
Large, flexible spacecraft are typically characterized by a large number of significant elastic modes with very small inherent damping, low, closely spaced natural frequencies, and the lack of accurate knowledge of the structural parameters. Summarized here is some recent research on the design of robust controllers for such spacecraft, which will maintain stability, and possible performance, despite these problems. Two types of controllers are considered, the first being the linear-quadratic-Gaussian-(LQG)-type. The second type utilizes output feedback using collocated sensors and actuators. The problem of designing robust LQG-type controllers using the frequency domain loop transfer recovery (LTR) method is considered, and the method is applied to a large antenna model. Analytical results regarding the regions of stability for LQG-type controllers in the presence of actuator nonlinearities are also presented. The results obtained for the large antenna indicate that the LQG/LTR method is a promising approach for control system design for flexible spacecraft. For the second type of controllers (collocated controllers), it is proved that the stability is maintained in the presence of certain commonly encountered nonlinearities and first-order actuator dynamics. These results indicate that collocated controllers are good candidates for robust control in situations where model errors are large.
Robust controller design for a skid to turn missile
NASA Astrophysics Data System (ADS)
Sreenatha, A. G.; Rajhans, Vivek; Bhardwaj, Neeraj
1999-11-01
The design and analysis of Robust Autopilot for skid-to-turn missile is presented. Two of the popular Robust Controller design approaches, The Loop Shaping Design Procedure (LSDP) and The Robust Eigenstructure Assignment are considered. The missile model considered in the present work is having lightly damped modes and non-minimum phase zeros, with stringent performance requirements. Numerical results are presented to evaluate the Robustness of stability and performance of the controller. Merits and demerits of the above said methodologies are brought out clearly as applied to this specific plant.
Evaluating efficiency and robustness in cilia design
NASA Astrophysics Data System (ADS)
Guo, Hanliang; Kanso, Eva
2016-03-01
Motile cilia are used by many eukaryotic cells to transport flow. Cilia-driven flows are important to many physiological functions, yet a deep understanding of the interplay between the mechanical structure of cilia and their physiological functions in healthy and diseased conditions remains elusive. To develop such an understanding, one needs a quantitative framework to assess cilia performance and robustness when subject to perturbations in the cilia apparatus. Here we link cilia design (beating patterns) to function (flow transport) in the context of experimentally and theoretically derived cilia models. We particularly examine the optimality and robustness of cilia design. Optimality refers to efficiency of flow transport, while robustness is defined as low sensitivity to variations in the design parameters. We find that suboptimal designs can be more robust than optimal ones. That is, designing for the most efficient cilium does not guarantee robustness. These findings have significant implications on the understanding of cilia design in artificial and biological systems.
Evaluating efficiency and robustness in cilia design.
Guo, Hanliang; Kanso, Eva
2016-03-01
Motile cilia are used by many eukaryotic cells to transport flow. Cilia-driven flows are important to many physiological functions, yet a deep understanding of the interplay between the mechanical structure of cilia and their physiological functions in healthy and diseased conditions remains elusive. To develop such an understanding, one needs a quantitative framework to assess cilia performance and robustness when subject to perturbations in the cilia apparatus. Here we link cilia design (beating patterns) to function (flow transport) in the context of experimentally and theoretically derived cilia models. We particularly examine the optimality and robustness of cilia design. Optimality refers to efficiency of flow transport, while robustness is defined as low sensitivity to variations in the design parameters. We find that suboptimal designs can be more robust than optimal ones. That is, designing for the most efficient cilium does not guarantee robustness. These findings have significant implications on the understanding of cilia design in artificial and biological systems. PMID:27078459
Design of flight control systems via robust decoupled servomechanism theory
NASA Technical Reports Server (NTRS)
Wang, S.-H.; Davison, E. J.
1979-01-01
Decoupling theory and robust servomechanism theory are applied to the design of linear multivariable systems with large parameter variations. In addition to being approximately decoupled in the transient period, the over-all system achieves tracking and disturbance rejection robustly in the steady state. An example in flight control system is given.
Robust Design Optimization via Failure Domain Bounding
NASA Technical Reports Server (NTRS)
Crespo, Luis G.; Kenny, Sean P.; Giesy, Daniel P.
2007-01-01
This paper extends and applies the strategies recently developed by the authors for handling constraints under uncertainty to robust design optimization. For the scope of this paper, robust optimization is a methodology aimed at problems for which some parameters are uncertain and are only known to belong to some uncertainty set. This set can be described by either a deterministic or a probabilistic model. In the methodology developed herein, optimization-based strategies are used to bound the constraint violation region using hyper-spheres and hyper-rectangles. By comparing the resulting bounding sets with any given uncertainty model, it can be determined whether the constraints are satisfied for all members of the uncertainty model (i.e., constraints are feasible) or not (i.e., constraints are infeasible). If constraints are infeasible and a probabilistic uncertainty model is available, upper bounds to the probability of constraint violation can be efficiently calculated. The tools developed enable approximating not only the set of designs that make the constraints feasible but also, when required, the set of designs for which the probability of constraint violation is below a prescribed admissible value. When constraint feasibility is possible, several design criteria can be used to shape the uncertainty model of performance metrics of interest. Worst-case, least-second-moment, and reliability-based design criteria are considered herein. Since the problem formulation is generic and the tools derived only require standard optimization algorithms for their implementation, these strategies are easily applicable to a broad range of engineering problems.
Towards designing robust coupled networks
Schneider, Christian M.; Yazdani, Nuri; Araújo, Nuno A. M.; Havlin, Shlomo; Herrmann, Hans J.
2013-01-01
Natural and technological interdependent systems have been shown to be highly vulnerable due to cascading failures and an abrupt collapse of global connectivity under initial failure. Mitigating the risk by partial disconnection endangers their functionality. Here we propose a systematic strategy of selecting a minimum number of autonomous nodes that guarantee a smooth transition in robustness. Our method which is based on betweenness is tested on various examples including the famous 2003 electrical blackout of Italy. We show that, with this strategy, the necessary number of autonomous nodes can be reduced by a factor of five compared to a random choice. We also find that the transition to abrupt collapse follows tricritical scaling characterized by a set of exponents which is independent on the protection strategy. PMID:23752705
Robust holographic storage system design.
Watanabe, Takahiro; Watanabe, Minoru
2011-11-21
Demand is increasing daily for large data storage systems that are useful for applications in spacecraft, space satellites, and space robots, which are all exposed to radiation-rich space environment. As candidates for use in space embedded systems, holographic storage systems are promising because they can easily provided the demanded large-storage capability. Particularly, holographic storage systems, which have no rotation mechanism, are demanded because they are virtually maintenance-free. Although a holographic memory itself is an extremely robust device even in a space radiation environment, its associated lasers and drive circuit devices are vulnerable. Such vulnerabilities sometimes engendered severe problems that prevent reading of all contents of the holographic memory, which is a turn-off failure mode of a laser array. This paper therefore presents a proposal for a recovery method for the turn-off failure mode of a laser array on a holographic storage system, and describes results of an experimental demonstration. PMID:22109441
Robust Decentralized Controller Design: Subsystem Approach
NASA Astrophysics Data System (ADS)
Rosinová, Danica; Thuan, Nguyen Quang; Veselý, Vojtech; Marko, L'ubomír
2012-01-01
The paper addresses the problem of the robust output feedback PI controller design for complex large-scale stable systems with a state decentralized control structure. A decentralized control design procedure is proposed for static output feedback control which is based on solving robust control design problems of subsystems' size. The presented approach is based
A robust optimization methodology for preliminary aircraft design
NASA Astrophysics Data System (ADS)
Prigent, S.; Maréchal, P.; Rondepierre, A.; Druot, T.; Belleville, M.
2016-05-01
This article focuses on a robust optimization of an aircraft preliminary design under operational constraints. According to engineers' know-how, the aircraft preliminary design problem can be modelled as an uncertain optimization problem whose objective (the cost or the fuel consumption) is almost affine, and whose constraints are convex. It is shown that this uncertain optimization problem can be approximated in a conservative manner by an uncertain linear optimization program, which enables the use of the techniques of robust linear programming of Ben-Tal, El Ghaoui, and Nemirovski [Robust Optimization, Princeton University Press, 2009]. This methodology is then applied to two real cases of aircraft design and numerical results are presented.
Robust Crossfeed Design for Hovering Rotorcraft
NASA Technical Reports Server (NTRS)
Catapang, David R.
1993-01-01
Control law design for rotorcraft fly-by-wire systems normally attempts to decouple angular responses using fixed-gain crossfeeds. This approach can lead to poor decoupling over the frequency range of pilot inputs and increase the load on the feedback loops. In order to improve the decoupling performance, dynamic crossfeeds may be adopted. Moreover, because of the large changes that occur in rotorcraft dynamics due to small changes about the nominal design condition, especially for near-hovering flight, the crossfeed design must be 'robust'. A new low-order matching method is presented here to design robust crossfeed compensators for multi-input, multi-output (MIMO) systems. The technique identifies degrees-of-freedom that can be decoupled using crossfeeds, given an anticipated set of parameter variations for the range of flight conditions of concern. Cross-coupling is then reduced for degrees-of-freedom that can use crossfeed compensation by minimizing off-axis response magnitude average and variance. Results are presented for the analysis of pitch, roll, yaw and heave coupling of the UH-60 Black Hawk helicopter in near-hovering flight. Robust crossfeeds are designed that show significant improvement in decoupling performance and robustness over nominal, single design point, compensators. The design method and results are presented in an easily used graphical format that lends significant physical insight to the design procedure. This plant pre-compensation technique is an appropriate preliminary step to the design of robust feedback control laws for rotorcraft.
Robust Tensioned Kevlar Suspension Design
NASA Technical Reports Server (NTRS)
Young, Joseph B.; Naylor, Bret J.; Holmes, Warren A.
2012-01-01
One common but challenging problem in cryogenic engineering is to produce a mount that has excellent thermal isolation but is also rigid. Such mounts can be achieved by suspending the load from a network of fibers or strings held in tension. Kevlar fibers are often used for this purpose owing to their high strength and low thermal conductivity. A suite of compact design elements has been developed to improve the reliability of suspension systems made of Kevlar.
Design optimization for cost and quality: The robust design approach
NASA Technical Reports Server (NTRS)
Unal, Resit
1990-01-01
Designing reliable, low cost, and operable space systems has become the key to future space operations. Designing high quality space systems at low cost is an economic and technological challenge to the designer. A systematic and efficient way to meet this challenge is a new method of design optimization for performance, quality, and cost, called Robust Design. Robust Design is an approach for design optimization. It consists of: making system performance insensitive to material and subsystem variation, thus allowing the use of less costly materials and components; making designs less sensitive to the variations in the operating environment, thus improving reliability and reducing operating costs; and using a new structured development process so that engineering time is used most productively. The objective in Robust Design is to select the best combination of controllable design parameters so that the system is most robust to uncontrollable noise factors. The robust design methodology uses a mathematical tool called an orthogonal array, from design of experiments theory, to study a large number of decision variables with a significantly small number of experiments. Robust design also uses a statistical measure of performance, called a signal-to-noise ratio, from electrical control theory, to evaluate the level of performance and the effect of noise factors. The purpose is to investigate the Robust Design methodology for improving quality and cost, demonstrate its application by the use of an example, and suggest its use as an integral part of space system design process.
Robust Control Design for Large Space Structures
NASA Technical Reports Server (NTRS)
Eastman, W. L.; Bossi, J. A.
1985-01-01
The control design problem for the class of future spacecraft referred to as large space structures (LSS) is by now well known. The issue is the reduced order control of a very high order, lightly damped system with uncertain system parameters, particularly in the high frequency modes. A design methodology which incorporates robustness considerations as part of the design process is presented. Combining pertinent results from multivariable systems theory and optimal control and estimation, LQG eigenstructure assignment and LQG frequency shaping, were used to improve singular value robustness measures in the presence of control and observation spillover.
Robust linear quadratic designs with respect to parameter uncertainty
NASA Technical Reports Server (NTRS)
Douglas, Joel; Athans, Michael
1992-01-01
The authors derive a linear quadratic regulator (LQR) which is robust to parametric uncertainty by using the overbounding method of I. R. Petersen and C. V. Hollot (1986). The resulting controller is determined from the solution of a single modified Riccati equation. It is shown that, when applied to a structural system, the controller gains add robustness by minimizing the potential energy of uncertain stiffness elements, and minimizing the rate of dissipation of energy through uncertain damping elements. A worst-case disturbance in the direction of the uncertainty is also considered. It is proved that performance robustness has been increased with the robust LQR when compared to a mismatched LQR design where the controller is designed on the nominal system, but applied to the actual uncertain system.
Extensibility of a linear rapid robust design methodology
NASA Astrophysics Data System (ADS)
Steinfeldt, Bradley A.; Braun, Robert D.
2016-05-01
The extensibility of a linear rapid robust design methodology is examined. This analysis is approached from a computational cost and accuracy perspective. The sensitivity of the solution's computational cost is examined by analysing effects such as the number of design variables, nonlinearity of the CAs, and nonlinearity of the response in addition to several potential complexity metrics. Relative to traditional robust design methods, the linear rapid robust design methodology scaled better with the size of the problem and had performance that exceeded the traditional techniques examined. The accuracy of applying a method with linear fundamentals to nonlinear problems was examined. It is observed that if the magnitude of nonlinearity is less than 1000 times that of the nominal linear response, the error associated with applying successive linearization will result in ? errors in the response less than 10% compared to the full nonlinear error.
Robust regression applied to fractal/multifractal analysis.
NASA Astrophysics Data System (ADS)
Portilla, F.; Valencia, J. L.; Tarquis, A. M.; Saa-Requejo, A.
2012-04-01
Fractal and multifractal are concepts that have grown increasingly popular in recent years in the soil analysis, along with the development of fractal models. One of the common steps is to calculate the slope of a linear fit commonly using least squares method. This shouldn't be a special problem, however, in many situations using experimental data the researcher has to select the range of scales at which is going to work neglecting the rest of points to achieve the best linearity that in this type of analysis is necessary. Robust regression is a form of regression analysis designed to circumvent some limitations of traditional parametric and non-parametric methods. In this method we don't have to assume that the outlier point is simply an extreme observation drawn from the tail of a normal distribution not compromising the validity of the regression results. In this work we have evaluated the capacity of robust regression to select the points in the experimental data used trying to avoid subjective choices. Based on this analysis we have developed a new work methodology that implies two basic steps: • Evaluation of the improvement of linear fitting when consecutive points are eliminated based on R p-value. In this way we consider the implications of reducing the number of points. • Evaluation of the significance of slope difference between fitting with the two extremes points and fitted with the available points. We compare the results applying this methodology and the common used least squares one. The data selected for these comparisons are coming from experimental soil roughness transect and simulated based on middle point displacement method adding tendencies and noise. The results are discussed indicating the advantages and disadvantages of each methodology. Acknowledgements Funding provided by CEIGRAM (Research Centre for the Management of Agricultural and Environmental Risks) and by Spanish Ministerio de Ciencia e Innovación (MICINN) through project no
Robustness Analysis and Optimally Robust Control Design via Sum-of-Squares
NASA Technical Reports Server (NTRS)
Dorobantu, Andrei; Crespo, Luis G.; Seiler, Peter J.
2012-01-01
A control analysis and design framework is proposed for systems subject to parametric uncertainty. The underlying strategies are based on sum-of-squares (SOS) polynomial analysis and nonlinear optimization to design an optimally robust controller. The approach determines a maximum uncertainty range for which the closed-loop system satisfies a set of stability and performance requirements. These requirements, de ned as inequality constraints on several metrics, are restricted to polynomial functions of the uncertainty. To quantify robustness, SOS analysis is used to prove that the closed-loop system complies with the requirements for a given uncertainty range. The maximum uncertainty range, calculated by assessing a sequence of increasingly larger ranges, serves as a robustness metric for the closed-loop system. To optimize the control design, nonlinear optimization is used to enlarge the maximum uncertainty range by tuning the controller gains. Hence, the resulting controller is optimally robust to parametric uncertainty. This approach balances the robustness margins corresponding to each requirement in order to maximize the aggregate system robustness. The proposed framework is applied to a simple linear short-period aircraft model with uncertain aerodynamic coefficients.
NASA Technical Reports Server (NTRS)
Bayard, David S.; Chiang, Richard Y.
1996-01-01
This paper demonstrates an approach to frequency domain identification for the explicit purpose of designing robust H(infinity) controllers. The approach transforms raw experimental data into a plant set estimate directly usable by modern robust control design software(e.g., Matlab Robust Control Toolboxes [11][2]). A key issue in control design from raw data is the question of whether the controller will work when applied to the true system. The main feature fo this approach is that the resulting controller in guaranteed to work as designed(when applied to the true system) to a prescribed statistical confidence. While the overall methodology addresses key theoretical issues, it has at the same time been specifically designed to support practical implementations. A simulation example is included to demonstrate the overall approach.
A method for designing robust multivariable feedback systems
NASA Technical Reports Server (NTRS)
Milich, David Albert; Athans, Michael; Valavani, Lena; Stein, Gunter
1988-01-01
A new methodology is developed for the synthesis of linear, time-invariant (LTI) controllers for multivariable LTI systems. The aim is to achieve stability and performance robustness of the feedback system in the presence of multiple unstructured uncertainty blocks; i.e., to satisfy a frequency-domain inequality in terms of the structured singular value. The design technique is referred to as the Causality Recovery Methodology (CRM). Starting with an initial (nominally) stabilizing compensator, the CRM produces a closed-loop system whose performance-robustness is at least as good as, and hopefully superior to, that of the original design. The robustness improvement is obtained by solving an infinite-dimensional, convex optimization program. A finite-dimensional implementation of the CRM was developed, and it was applied to a multivariate design example.
A method for designing robust multivariable feedback systems
NASA Technical Reports Server (NTRS)
Milich, David A.; Athans, Michael; Valavani, Lena; Stein, Gunter
1988-01-01
A new methodology is developed for the synthesis of linear, time-invariant (LTI) controllers for multivariable LTI systems. The aim is to achieve stability and performance robustness of the feedback system in the presence of multiple unstructured uncertainty blocks; i.e., to satisfy a frequency-domain inequality in terms of the structured singular value. The design technique is referred to as the causality recovery methodology (CRM). Starting with an initial (nominally) stabilizing compensator, the CRM produces a closed-loop system whose performance-robustness is at least as good as, and hopefully superior to, that of the original design. The robustness improvement is obtained by solving an infinite-dimensional, convex optimization program. A finite-dimensional implementation of the CRM was developed, and it was applied to a multivariate design example.
Matlab as a robust control design tool
NASA Technical Reports Server (NTRS)
Gregory, Irene M.
1994-01-01
This presentation introduces Matlab as a tool used in flight control research. The example used to illustrate some of the capabilities of this software is a robust controller designed for a single stage to orbit air breathing vehicles's ascent to orbit. The global requirements of the controller are to stabilize the vehicle and follow a trajectory in the presence of atmospheric disturbances and strong dynamic coupling between airframe and propulsion.
NASA Technical Reports Server (NTRS)
Ryan, R.
1993-01-01
Robustness is a buzz word common to all newly proposed space systems design as well as many new commercial products. The image that one conjures up when the word appears is a 'Paul Bunyon' (lumberjack design), strong and hearty; healthy with margins in all aspects of the design. In actuality, robustness is much broader in scope than margins, including such factors as simplicity, redundancy, desensitization to parameter variations, control of parameter variations (environments flucation), and operational approaches. These must be traded with concepts, materials, and fabrication approaches against the criteria of performance, cost, and reliability. This includes manufacturing, assembly, processing, checkout, and operations. The design engineer or project chief is faced with finding ways and means to inculcate robustness into an operational design. First, however, be sure he understands the definition and goals of robustness. This paper will deal with these issues as well as the need for the requirement for robustness.
A Robust Control Design Framework for Substructure Models
NASA Technical Reports Server (NTRS)
Lim, Kyong B.
1994-01-01
A framework for designing control systems directly from substructure models and uncertainties is proposed. The technique is based on combining a set of substructure robust control problems by an interface stiffness matrix which appears as a constant gain feedback. Variations of uncertainties in the interface stiffness are treated as a parametric uncertainty. It is shown that multivariable robust control can be applied to generate centralized or decentralized controllers that guarantee performance with respect to uncertainties in the interface stiffness, reduced component modes and external disturbances. The technique is particularly suited for large, complex, and weakly coupled flexible structures.
Robustness of speckle imaging techniques applied to horizontal imaging scenarios
NASA Astrophysics Data System (ADS)
Bos, Jeremy P.
Atmospheric turbulence near the ground severely limits the quality of imagery acquired over long horizontal paths. In defense, surveillance, and border security applications, there is interest in deploying man-portable, embedded systems incorporating image reconstruction to improve the quality of imagery available to operators. To be effective, these systems must operate over significant variations in turbulence conditions while also subject to other variations due to operation by novice users. Systems that meet these requirements and are otherwise designed to be immune to the factors that cause variation in performance are considered robust. In addition to robustness in design, the portable nature of these systems implies a preference for systems with a minimum level of computational complexity. Speckle imaging methods are one of a variety of methods recently been proposed for use in man-portable horizontal imagers. In this work, the robustness of speckle imaging methods is established by identifying a subset of design parameters that provide immunity to the expected variations in operating conditions while minimizing the computation time necessary for image recovery. This performance evaluation is made possible using a novel technique for simulating anisoplanatic image formation. I find that incorporate as few as 15 image frames and 4 estimates of the object phase per reconstructed frame provide an average reduction of 45% reduction in Mean Squared Error (MSE) and 68% reduction in deviation in MSE. In addition, the Knox-Thompson phase recovery method is demonstrated to produce images in half the time required by the bispectrum. Finally, it is shown that certain blind image quality metrics can be used in place of the MSE to evaluate reconstruction quality in field scenarios. Using blind metrics rather depending on user estimates allows for reconstruction quality that differs from the minimum MSE by as little as 1%, significantly reducing the deviation in
Design of robust failure detection filters
NASA Technical Reports Server (NTRS)
San Martin, A. M.; Vander Velde, W. E.
1986-01-01
An essential aspect of the design of control systems for large, flexible spacecraft is fault tolerance. Because it is anticipated that a large number of sensors and actuators will be required to realize good control over these assemblies, the detection and isolation of component failures cannot be based on direct comparisons among replicated components. Instead, the notion of 'analytic redundancy' must be employed for the FDI function. Unfortunately this makes the FDI function sensitive to modeling errors which are certain to exist in the large space structure problem due to model truncation and parameter uncertainty. This paper addresses the robustness to model error of one method of FDI residual generation - the failure detection filter. Initial designs were found to be extremely sensitive to modeling error. The sources of this sensitivity are analyzed and modifications to the design are suggested. The improved filter is shown to have much better visibility of the failure signatures relative to the background due to modeling error.
Design analysis, robust methods, and stress classification
Bees, W.J.
1993-01-01
This special edition publication volume is comprised of papers presented at the 1993 ASME Pressure Vessels and Piping Conference, July 25--29, 1993 in Denver, Colorado. The papers were prepared for presentations in technical sessions developed under the auspices of the PVPD Committees on Computer Technology, Design and Analysis, Operations Applications and Components. The topics included are: Analysis of Pressure Vessels and Components; Expansion Joints; Robust Methods; Stress Classification; and Non-Linear Analysis. Individual papers have been processed separately for inclusion in the appropriate data bases.
System identification for robust control design
Dohner, J.L.
1995-04-01
System identification for the purpose of robust control design involves estimating a nominal model of a physical system and the uncertainty bounds of that nominal model via the use of experimentally measured input/output data. Although many algorithms have been developed to identify nominal models, little effort has been directed towards identifying uncertainty bounds. Therefore, in this document, a discussion of both nominal model identification and bounded output multiplicative uncertainty identification will be presented. This document is divided into several sections. Background information relevant to system identification and control design will be presented. A derivation of eigensystem realization type algorithms will be presented. An algorithm will be developed for calculating the maximum singular value of output multiplicative uncertainty from measured data. An application will be given involving the identification of a complex system with aliased dynamics, feedback control, and exogenous noise disturbances. And, finally, a short discussion of results will be presented.
Computational methods of robust controller design for aerodynamic flutter suppression
NASA Technical Reports Server (NTRS)
Anderson, L. R.
1981-01-01
The development of Riccati iteration, a tool for the design and analysis of linear control systems is examined. First, Riccati iteration is applied to the problem of pole placement and order reduction in two-time scale control systems. Order reduction, yielding a good approximation to the original system, is demonstrated using a 16th order linear model of a turbofan engine. Next, a numerical method for solving the Riccati equation is presented and demonstrated for a set of eighth order random examples. A literature review of robust controller design methods follows which includes a number of methods for reducing the trajectory and performance index sensitivity in linear regulators. Lastly, robust controller design for large parameter variations is discussed.
Robust Bayesian decision theory applied to optimal dosage.
Abraham, Christophe; Daurès, Jean-Pierre
2004-04-15
We give a model for constructing an utility function u(theta,d) in a dose prescription problem. theta and d denote respectively the patient state of health and the dose. The construction of u is based on the conditional probabilities of several variables. These probabilities are described by logistic models. Obviously, u is only an approximation of the true utility function and that is why we investigate the sensitivity of the final decision with respect to the utility function. We construct a class of utility functions from u and approximate the set of all Bayes actions associated to that class. Then, we measure the sensitivity as the greatest difference between the expected utilities of two Bayes actions. Finally, we apply these results to weighing up a chemotherapy treatment of lung cancer. This application emphasizes the importance of measuring robustness through the utility of decisions rather than the decisions themselves. PMID:15057878
Robust control systems design by H-infinity optimization theory
NASA Technical Reports Server (NTRS)
Chang, B. C.; Li, X. P.; Banda, S. S.; Yeh, H. H.
1991-01-01
In this paper, step-by-step procedures of applying the H-infinity theory to robust control systems design are given. The objective of the paper is to eliminate the possible difficulties a control engineer may encounter in applying H-infinity control theory and to clear up some misconceptions about H-infinity theory like high-gain controller and numerical obstacles, etc. An efficient algorithm is used to compute the optimal H-infinity norm. The Glover and Doyle (1988) controller formulas are slightly modified and used to construct an optimal controller without any numerical difficulties.
Robust Path Planning and Feedback Design Under Stochastic Uncertainty
NASA Technical Reports Server (NTRS)
Blackmore, Lars
2008-01-01
Autonomous vehicles require optimal path planning algorithms to achieve mission goals while avoiding obstacles and being robust to uncertainties. The uncertainties arise from exogenous disturbances, modeling errors, and sensor noise, which can be characterized via stochastic models. Previous work defined a notion of robustness in a stochastic setting by using the concept of chance constraints. This requires that mission constraint violation can occur with a probability less than a prescribed value.In this paper we describe a novel method for optimal chance constrained path planning with feedback design. The approach optimizes both the reference trajectory to be followed and the feedback controller used to reject uncertainty. Our method extends recent results in constrained control synthesis based on convex optimization to solve control problems with nonconvex constraints. This extension is essential for path planning problems, which inherently have nonconvex obstacle avoidance constraints. Unlike previous approaches to chance constrained path planning, the new approach optimizes the feedback gain as wellas the reference trajectory.The key idea is to couple a fast, nonconvex solver that does not take into account uncertainty, with existing robust approaches that apply only to convex feasible regions. By alternating between robust and nonrobust solutions, the new algorithm guarantees convergence to a global optimum. We apply the new method to an unmanned aircraft and show simulation results that demonstrate the efficacy of the approach.
Robust PID Parameter Design for Embedded Temperature Control System Using Taguchi Method
NASA Astrophysics Data System (ADS)
Suzuki, Arata; Sugimoto, Kenji
This paper proposes a robust PID parameter design scheme using Taguchi's robust design method. This scheme is applied to an embedded PID temperature control system which is affected by outside (room) temperature. The effectiveness of this scheme is verified experimentally with a cooking household appliance.
Robust design of polyrhythmic neural circuits
NASA Astrophysics Data System (ADS)
Schwabedal, Justus T. C.; Neiman, Alexander B.; Shilnikov, Andrey L.
2014-08-01
Neural circuit motifs producing coexistent rhythmic patterns are treated as building blocks of multifunctional neuronal networks. We study the robustness of such a motif of inhibitory model neurons to reliably sustain bursting polyrhythms under random perturbations. Without noise, the exponential stability of each of the coexisting rhythms increases with strengthened synaptic coupling, thus indicating an increased robustness. Conversely, after adding noise we find that noise-induced rhythm switching intensifies if the coupling strength is increased beyond a critical value, indicating a decreased robustness. We analyze this stochastic arrhythmia and develop a generic description of its dynamic mechanism. Based on our mechanistic insight, we show how physiological parameters of neuronal dynamics and network coupling can be balanced to enhance rhythm robustness against noise. Our findings are applicable to a broad class of relaxation-oscillator networks, including Fitzhugh-Nagumo and other Hodgkin-Huxley-type networks.
Applying Software Design Methodology to Instructional Design
NASA Astrophysics Data System (ADS)
East, J. Philip
2004-12-01
The premise of this paper is that computer science has much to offer the endeavor of instructional improvement. Software design processes employed in computer science for developing software can be used for planning instruction and should improve instruction in much the same manner that design processes appear to have improved software. Techniques for examining the software development process can be applied to an examination of the instructional process. Furthermore, the computer science discipline is particularly well suited to these tasks. Thus, computer science can develop instructional design expertise for export to other disciplines to improve education in all disciplines and, eventually, at all levels.
Robust Decision-making Applied to Model Selection
Hemez, Francois M.
2012-08-06
The scientific and engineering communities are relying more and more on numerical models to simulate ever-increasingly complex phenomena. Selecting a model, from among a family of models that meets the simulation requirements, presents a challenge to modern-day analysts. To address this concern, a framework is adopted anchored in info-gap decision theory. The framework proposes to select models by examining the trade-offs between prediction accuracy and sensitivity to epistemic uncertainty. The framework is demonstrated on two structural engineering applications by asking the following question: Which model, of several numerical models, approximates the behavior of a structure when parameters that define each of those models are unknown? One observation is that models that are nominally more accurate are not necessarily more robust, and their accuracy can deteriorate greatly depending upon the assumptions made. It is posited that, as reliance on numerical models increases, establishing robustness will become as important as demonstrating accuracy.
Robust Design of Motor PWM Control using Modeling and Simulation
NASA Astrophysics Data System (ADS)
Zhan, Wei
A robust design method is developed for Pulse Width Modulation (PWM) motor speed control. A first principle model for DC permanent magnetic motor is used to build a Simulink model for simulation and analysis. Based on the simulation result, the main factors that contributed to the average speed variation are identified using Design of Experiment (DOE). A robust solution is derived to reduce the aver age speed control variation using Response Surface Method (RSM). The robustness of the new design is verified using the simulation model.
Analytical redundancy and the design of robust failure detection systems
NASA Technical Reports Server (NTRS)
Chow, E. Y.; Willsky, A. S.
1984-01-01
The Failure Detection and Identification (FDI) process is viewed as consisting of two stages: residual generation and decision making. It is argued that a robust FDI system can be achieved by designing a robust residual generation process. Analytical redundancy, the basis for residual generation, is characterized in terms of a parity space. Using the concept of parity relations, residuals can be generated in a number of ways and the design of a robust residual generation process can be formulated as a minimax optimization problem. An example is included to illustrate this design methodology. Previously announcedd in STAR as N83-20653
NASA Astrophysics Data System (ADS)
Hwang, Kwang-Hyeon; Lee, Kwon-Hee; Park, Gyung-Jin; Lee, Byeong-Leul; Cho, Yong-Chul; Lee, Seok-Han
2003-01-01
Recently, there has been considerable interest in micro gyroscopes made of silicon chips. These can be applied to many microelectromechanical systems, such as devices for stabilization, general rate control, directional pointing, autopilot systems, and missile control. A decoupled vibratory gyroscope has been fabricated and tested. In this research, design improvement is obtained from numerical analyses as well as from a theoretical design point of view. The existing design is analyzed by using the axiomatic approach, which provides a general framework for design. For axiomatic design, the functional requirements (FRs) are twofold: firstly, the natural frequencies should have fixed values, and secondly the system should be robust to large tolerances. According to the independence axiom, the design parameters (DPs) are classified into the same number of groups as the FRs. Each group of DPs is separately determined according to the sequence indicated by axiomatic design. When a group of DPs should be determined to enhance robustness, the Taguchi concept is employed to maintain robust performance regardless of the tolerances. It is noted that the Taguchi method is used as a unit process in the sequence of the axiomatic design.
A robust industrial accelerator window design
NASA Astrophysics Data System (ADS)
Schuetz, Marlin N.; Vroom, David A.
1998-06-01
An improved design for the thin metal foil window associated with high power industrial accelarators has been developed and tested. This design, which employs specifically shaped flanges, greatly reduce the stresses normally present on accelerators windows and has lead to longer window lifetime and a better means of window cooling.
Design for robustness of unique, multi-component engineering systems
NASA Astrophysics Data System (ADS)
Shelton, Kenneth A.
2007-12-01
The purpose of this research is to advance the science of conceptual designing for robustness in unique, multi-component engineering systems. Robustness is herein defined as the ability of an engineering system to operate within a desired performance range even if the actual configuration has differences from specifications within specified tolerances. These differences are caused by three sources, namely manufacturing errors, system degradation (operational wear and tear), and parts availability. Unique, multi-component engineering systems are defined as systems produced in unique or very small production numbers. They typically have design and manufacturing costs on the order of billions of dollars, and have multiple, competing performance objectives. Design time for these systems must be minimized due to competition, high manpower costs, long manufacturing times, technology obsolescence, and limited available manpower expertise. Most importantly, design mistakes cannot be easily corrected after the systems are operational. For all these reasons, robustness of these systems is absolutely critical. This research examines the space satellite industry in particular. Although inherent robustness assurance is absolutely critical, it is difficult to achieve in practice. The current state of the art for robustness in the industry is to overdesign components and subsystems with redundancy and margin. The shortfall is that it is not known if the added margins were either necessary or sufficient given the risk management preferences of the designer or engineering system customer. To address this shortcoming, new assessment criteria to evaluate robustness in design concepts have been developed. The criteria are comprised of the "Value Distance", addressing manufacturing errors and system degradation, and "Component Distance", addressing parts availability. They are based on an evolutionary computation format that uses a string of alleles to describe the components in the
Designing Robust Hierarchically Textured Oleophobic Fabrics.
Kleingartner, Justin A; Srinivasan, Siddarth; Truong, Quoc T; Sieber, Michael; Cohen, Robert E; McKinley, Gareth H
2015-12-01
Commercially available woven fabrics (e.g., nylon- or PET-based fabrics) possess inherently re-entrant textures in the form of cylindrical yarns and fibers. We analyze the liquid repellency of woven and nanotextured oleophobic fabrics using a nested model with n levels of hierarchy that is constructed from modular units of cylindrical and spherical building blocks. At each level of hierarchy, the density of the topographical features is captured using a dimensionless textural parameter D(n)*. For a plain-woven mesh comprised of chemically treated fiber bundles (n = 2), the tight packing of individual fibers in each bundle (D2* ≈ 1) imposes a geometric constraint on the maximum oleophobicity that can be achieved solely by modifying the surface energy of the coating. For liquid droplets contacting such tightly bundled fabrics with modified surface energies, we show that this model predicts a lower bound on the equilibrium contact angle of θ(E) ≈ 57° below which the Cassie–Baxter to Wenzel wetting transition occurs spontaneously, and this is validated experimentally. We demonstrate how the introduction of an additional higher order micro-/nanotexture onto the fibers (n = 3) is necessary to overcome this limit and create more robustly nonwetting fabrics. Finally, we show a simple experimental realization of the enhanced oleophobicity of fabrics by depositing spherical microbeads of poly(methyl methacrylate)/fluorodecyl polyhedral oligomeric silsesquioxane (fluorodecyl POSS) onto the fibers of a commercial woven nylon fabric. PMID:26473386
Robust sliding mode control applied to double Inverted pendulum system
Mahjoub, Sonia; Derbel, Nabil; Mnif, Faical
2009-03-05
A three hierarchical sliding mode control is presented for a class of an underactuated system which can overcome the mismatched perturbations. The considered underactuated system is a double inverted pendulum (DIP), can be modeled by three subsystems. Such structure allows the construction of several designs of hierarchies for the controller. For all hierarchical designs, the asymptotic stability of every layer sliding mode surface and the sliding mode surface of subsystems are proved theoretically by Barbalat's lemma. Simulation results show the validity of these methods.
Robust Control Design for Systems With Probabilistic Uncertainty
NASA Technical Reports Server (NTRS)
Crespo, Luis G.; Kenny, Sean P.
2005-01-01
This paper presents a reliability- and robustness-based formulation for robust control synthesis for systems with probabilistic uncertainty. In a reliability-based formulation, the probability of violating design requirements prescribed by inequality constraints is minimized. In a robustness-based formulation, a metric which measures the tendency of a random variable/process to cluster close to a target scalar/function is minimized. A multi-objective optimization procedure, which combines stability and performance requirements in time and frequency domains, is used to search for robustly optimal compensators. Some of the fundamental differences between the proposed strategy and conventional robust control methods are: (i) unnecessary conservatism is eliminated since there is not need for convex supports, (ii) the most likely plants are favored during synthesis allowing for probabilistic robust optimality, (iii) the tradeoff between robust stability and robust performance can be explored numerically, (iv) the uncertainty set is closely related to parameters with clear physical meaning, and (v) compensators with improved robust characteristics for a given control structure can be synthesized.
Object oriented simulation implementation in support of robust system design
Not Available
1993-04-01
A very brief description of two ``classes`` developed for use in design optimization and sensitivity analyses are given. These classes are used in simulations of systems in early design phases as well as system response assessments. The instanciated classes were coupled to system models to demonstrate the practically and efficiency of using these objects in complex robust design processes.
Design of robust level control system of nuclear steam generator
NASA Astrophysics Data System (ADS)
Lee, Y. J.; Na, M. G.
2007-12-01
The nuclear steam generator feedwater control system is designed by the robust control methods. The design is divided into two steps. First, the feedwater controller in the feedwater station is designed by H ∞ and MWS methods. Then the controller located on the feedback loop is designed both by classical PID and by robust technique. It is found that the feedback controller of simple PID whose coefficients vary with the power is proper for the system performance. The simulations show that the hybrid system of H ∞ and PID has a good performance with proper stability margins.
Apply Design Patterns to Refactor Software Design
NASA Technical Reports Server (NTRS)
Baggs, Rhoda; Shaykhian, Gholam Ali
2007-01-01
Refactoring software design is a method of changing software design while explicitly preserving its unique design functionalities. Presented approach is to utilize design patterns as the basis for refactoring software design. Comparison of a design solution will be made through C++ programming language examples to exploit this approach. Developing reusable component will be discussed, the paper presents that the construction of such components can diminish the added burden of both refactoring and the use of design patterns.
Robust synthetic biology design: stochastic game theory approach
Chen, Bor-Sen; Chang, Chia-Hung; Lee, Hsiao-Ching
2009-01-01
Motivation: Synthetic biology is to engineer artificial biological systems to investigate natural biological phenomena and for a variety of applications. However, the development of synthetic gene networks is still difficult and most newly created gene networks are non-functioning due to uncertain initial conditions and disturbances of extra-cellular environments on the host cell. At present, how to design a robust synthetic gene network to work properly under these uncertain factors is the most important topic of synthetic biology. Results: A robust regulation design is proposed for a stochastic synthetic gene network to achieve the prescribed steady states under these uncertain factors from the minimax regulation perspective. This minimax regulation design problem can be transformed to an equivalent stochastic game problem. Since it is not easy to solve the robust regulation design problem of synthetic gene networks by non-linear stochastic game method directly, the Takagi–Sugeno (T–S) fuzzy model is proposed to approximate the non-linear synthetic gene network via the linear matrix inequality (LMI) technique through the Robust Control Toolbox in Matlab. Finally, an in silico example is given to illustrate the design procedure and to confirm the efficiency and efficacy of the proposed robust gene design method. Availability: http://www.ee.nthu.edu.tw/bschen/SyntheticBioDesign_supplement.pdf Contact: bschen@ee.nthu.edu.tw Supplementary information: Supplementary data are available at Bioinformatics online. PMID:19435742
Robust control design verification using the modular modeling system
Edwards, R.M.; Ben-Abdennour, A.; Lee, K.Y.
1991-01-01
The Modular Modeling System (B W MMS) is being used as a design tool to verify robust controller designs for improving power plant performance while also providing fault-accommodating capabilities. These controllers are designed based on optimal control theory and are thus model based controllers which are targeted for implementation in a computer based digital control environment. The MMS is being successfully used to verify that the controllers are tolerant of uncertainties between the plant model employed in the controller and the actual plant; i.e., that they are robust. The two areas in which the MMS is being used for this purpose is in the design of (1) a reactor power controller with improved reactor temperature response, and (2) the design of a multiple input multiple output (MIMO) robust fault-accommodating controller for a deaerator level and pressure control problem.
Trading Robustness Requirements in Mars Entry Trajectory Design
NASA Technical Reports Server (NTRS)
Lafleur, Jarret M.
2009-01-01
One of the most important metrics characterizing an atmospheric entry trajectory in preliminary design is the size of its predicted landing ellipse. Often, requirements for this ellipse are set early in design and significantly influence both the expected scientific return from a particular mission and the cost of development. Requirements typically specify a certain probability level (6-level) for the prescribed ellipse, and frequently this latter requirement is taken at 36. However, searches for the justification of 36 as a robustness requirement suggest it is an empirical rule of thumb borrowed from non-aerospace fields. This paper presents an investigation into the sensitivity of trajectory performance to varying robustness (6-level) requirements. The treatment of robustness as a distinct objective is discussed, and an analysis framework is presented involving the manipulation of design variables to effect trades between performance and robustness objectives. The scenario for which this method is illustrated is the ballistic entry of an MSL-class Mars entry vehicle. Here, the design variable is entry flight path angle, and objectives are parachute deploy altitude performance and error ellipse robustness. Resulting plots show the sensitivities between these objectives and trends in the entry flight path angles required to design to these objectives. Relevance to the trajectory designer is discussed, as are potential steps for further development and use of this type of analysis.
Robust crossfeed design for hovering rotorcraft. M.S. Thesis
NASA Technical Reports Server (NTRS)
Catapang, David R.
1993-01-01
Control law design for rotorcraft fly-by-wire systems normally attempts to decouple angular responses using fixed-gain crossfeeds. This approach can lead to poor decoupling over the frequency range of pilot inputs and increase the load on the feedback loops. In order to improve the decoupling performance, dynamic crossfeeds may be adopted. Moreover, because of the large changes that occur in rotorcraft dynamics due to small changes about the nominal design condition, especially for near-hovering flight, the crossfeed design must be 'robust.' A new low-order matching method is presented here to design robost crossfeed compensators for multi-input, multi-output (MIMO) systems. The technique identifies degrees-of-freedom that can be decoupled using crossfeeds, given an anticipated set of parameter variations for the range of flight conditions of concern. Cross-coupling is then reduced for degrees-of-freedom that can use crossfeed compensation by minimizing off-axis response magnitude average and variance. Results are presented for the analysis of pitch, roll, yaw, and heave coupling of the UH-60 Black Hawk helicopter in near-hovering flight. Robust crossfeeds are designed that show significant improvement in decoupling performance and robustness over nominal, single design point, compensators. The design method and results are presented in an easily-used graphical format that lends significant physical insight to the design procedure. This plant pre-compensation technique is an appropriate preliminary step to the design of robust feedback control laws for rotorcraft.
Designing Flood Management Systems for Joint Economic and Ecological Robustness
NASA Astrophysics Data System (ADS)
Spence, C. M.; Grantham, T.; Brown, C. M.; Poff, N. L.
2015-12-01
Freshwater ecosystems across the United States are threatened by hydrologic change caused by water management operations and non-stationary climate trends. Nonstationary hydrology also threatens flood management systems' performance. Ecosystem managers and flood risk managers need tools to design systems that achieve flood risk reduction objectives while sustaining ecosystem functions and services in an uncertain hydrologic future. Robust optimization is used in water resources engineering to guide system design under climate change uncertainty. Using principles introduced by Eco-Engineering Decision Scaling (EEDS), we extend robust optimization techniques to design flood management systems that meet both economic and ecological goals simultaneously across a broad range of future climate conditions. We use three alternative robustness indices to identify flood risk management solutions that preserve critical ecosystem functions in a case study from the Iowa River, where recent severe flooding has tested the limits of the existing flood management system. We seek design modifications to the system that both reduce expected cost of flood damage while increasing ecologically beneficial inundation of riparian floodplains across a wide range of plausible climate futures. The first robustness index measures robustness as the fraction of potential climate scenarios in which both engineering and ecological performance goals are met, implicitly weighting each climate scenario equally. The second index builds on the first by using climate projections to weight each climate scenario, prioritizing acceptable performance in climate scenarios most consistent with climate projections. The last index measures robustness as mean performance across all climate scenarios, but penalizes scenarios with worse performance than average, rewarding consistency. Results stemming from alternate robustness indices reflect implicit assumptions about attitudes toward risk and reveal the
Enabling Rapid and Robust Structural Analysis During Conceptual Design
NASA Technical Reports Server (NTRS)
Eldred, Lloyd B.; Padula, Sharon L.; Li, Wu
2015-01-01
This paper describes a multi-year effort to add a structural analysis subprocess to a supersonic aircraft conceptual design process. The desired capabilities include parametric geometry, automatic finite element mesh generation, static and aeroelastic analysis, and structural sizing. The paper discusses implementation details of the new subprocess, captures lessons learned, and suggests future improvements. The subprocess quickly compares concepts and robustly handles large changes in wing or fuselage geometry. The subprocess can rank concepts with regard to their structural feasibility and can identify promising regions of the design space. The automated structural analysis subprocess is deemed robust and rapid enough to be included in multidisciplinary conceptual design and optimization studies.
Design for robustness of unique, multi-component engineering systems
NASA Astrophysics Data System (ADS)
Shelton, Kenneth A.
2007-12-01
The purpose of this research is to advance the science of conceptual designing for robustness in unique, multi-component engineering systems. Robustness is herein defined as the ability of an engineering system to operate within a desired performance range even if the actual configuration has differences from specifications within specified tolerances. These differences are caused by three sources, namely manufacturing errors, system degradation (operational wear and tear), and parts availability. Unique, multi-component engineering systems are defined as systems produced in unique or very small production numbers. They typically have design and manufacturing costs on the order of billions of dollars, and have multiple, competing performance objectives. Design time for these systems must be minimized due to competition, high manpower costs, long manufacturing times, technology obsolescence, and limited available manpower expertise. Most importantly, design mistakes cannot be easily corrected after the systems are operational. For all these reasons, robustness of these systems is absolutely critical. This research examines the space satellite industry in particular. Although inherent robustness assurance is absolutely critical, it is difficult to achieve in practice. The current state of the art for robustness in the industry is to overdesign components and subsystems with redundancy and margin. The shortfall is that it is not known if the added margins were either necessary or sufficient given the risk management preferences of the designer or engineering system customer. To address this shortcoming, new assessment criteria to evaluate robustness in design concepts have been developed. The criteria are comprised of the "Value Distance", addressing manufacturing errors and system degradation, and "Component Distance", addressing parts availability. They are based on an evolutionary computation format that uses a string of alleles to describe the components in the
Robust Control Design for Uncertain Nonlinear Dynamic Systems
NASA Technical Reports Server (NTRS)
Kenny, Sean P.; Crespo, Luis G.; Andrews, Lindsey; Giesy, Daniel P.
2012-01-01
Robustness to parametric uncertainty is fundamental to successful control system design and as such it has been at the core of many design methods developed over the decades. Despite its prominence, most of the work on robust control design has focused on linear models and uncertainties that are non-probabilistic in nature. Recently, researchers have acknowledged this disparity and have been developing theory to address a broader class of uncertainties. This paper presents an experimental application of robust control design for a hybrid class of probabilistic and non-probabilistic parametric uncertainties. The experimental apparatus is based upon the classic inverted pendulum on a cart. The physical uncertainty is realized by a known additional lumped mass at an unknown location on the pendulum. This unknown location has the effect of substantially altering the nominal frequency and controllability of the nonlinear system, and in the limit has the capability to make the system neutrally stable and uncontrollable. Another uncertainty to be considered is a direct current motor parameter. The control design objective is to design a controller that satisfies stability, tracking error, control power, and transient behavior requirements for the largest range of parametric uncertainties. This paper presents an overview of the theory behind the robust control design methodology and the experimental results.
Existential Design Applied in Universal Design Settings.
Torkildsby, Anne Britt
2016-01-01
The critical design method aims to discuss ways of opening up the (design) brief when planning, designing, building, operating and maintaining the future of the built environment - public as well as private, indoor as well as outdoor. Focusing on "designials" (fundamental forms of design being), the methodology intends to illustrate the fact that objects; including buildings, parks, transportation systems, etc. may directly encroach upon certain "existentials" (fundamental forms of human being) - thus shed light on how a design process is normally conducted, and furthermore, how that affects people's existential well-being. PMID:27534284
GPS baseline configuration design based on robustness analysis
NASA Astrophysics Data System (ADS)
Yetkin, M.; Berber, M.
2012-11-01
The robustness analysis results obtained from a Global Positioning System (GPS) network are dramatically influenced by the configuration
Towards Robust Designs Via Multiple-Objective Optimization Methods
NASA Technical Reports Server (NTRS)
Man Mohan, Rai
2006-01-01
Fabricating and operating complex systems involves dealing with uncertainty in the relevant variables. In the case of aircraft, flow conditions are subject to change during operation. Efficiency and engine noise may be different from the expected values because of manufacturing tolerances and normal wear and tear. Engine components may have a shorter life than expected because of manufacturing tolerances. In spite of the important effect of operating- and manufacturing-uncertainty on the performance and expected life of the component or system, traditional aerodynamic shape optimization has focused on obtaining the best design given a set of deterministic flow conditions. Clearly it is important to both maintain near-optimal performance levels at off-design operating conditions, and, ensure that performance does not degrade appreciably when the component shape differs from the optimal shape due to manufacturing tolerances and normal wear and tear. These requirements naturally lead to the idea of robust optimal design wherein the concept of robustness to various perturbations is built into the design optimization procedure. The basic ideas involved in robust optimal design will be included in this lecture. The imposition of the additional requirement of robustness results in a multiple-objective optimization problem requiring appropriate solution procedures. Typically the costs associated with multiple-objective optimization are substantial. Therefore efficient multiple-objective optimization procedures are crucial to the rapid deployment of the principles of robust design in industry. Hence the companion set of lecture notes (Single- and Multiple-Objective Optimization with Differential Evolution and Neural Networks ) deals with methodology for solving multiple-objective Optimization problems efficiently, reliably and with little user intervention. Applications of the methodologies presented in the companion lecture to robust design will be included here. The
Applying Software Design Methodology to Instructional Design
ERIC Educational Resources Information Center
East, J. Philip
2004-01-01
The premise of this paper is that computer science has much to offer the endeavor of instructional improvement. Software design processes employed in computer science for developing software can be used for planning instruction and should improve instruction in much the same manner that design processes appear to have improved software. Techniques…
Design and tuning of robust PID controller for HVAC systems
Kasahara, Masato; Matsuba, Tadahiko; Kuzuu, Yoshiaki; Yamazaki, Takanori; Hashimoto, Yukihiro; Kamimura, Kazuyuki; Kurosu, Shigeru
1999-07-01
This paper concerns the development of a new design and tuning method for use with robust proportional-plus-integral-plus-derivative (PID) controllers that are commonly used in the heating, ventilating, and air-conditioning (HVAC) fields. The robust PID controller is designed for temperature control of a single-zone environmental space. Although the dynamics of environmental space are described by higher-order transfer functions, most HVAC plants are approximated by first-order lag plus deadtime systems. Its control performance is examined for this commonly approximated controlled plant. Since most HVAC plants are complex with nonlinearity, distributed parameters, and multivariables, a single set of PID gains does not necessarily yield a satisfactory control performance. For this reason, the PID controller must be designed as a robust control system considering model uncertainty caused by changes in characteristics of the plant. The PID gains obtained by solving a two-disk type of mixed sensitivity problem can be modified by contrast to those tuned by the traditional Ziegler-Nichols rule. The results, which are surprisingly simple, are given as linear functions of ratio of deadtime to time constant for robustness. The numerical simulation and the experiments on a commercial-size test plant for air conditioning suggest that the robust PID controller proposed in this paper is effective enough for practical applications.
Robust optimization for water distribution systems least cost design
NASA Astrophysics Data System (ADS)
Perelman, Lina; Housh, Mashor; Ostfeld, Avi
2013-10-01
The objective of the least cost design problem of a water distribution system is to find its minimum cost with discrete diameters as decision variables and hydraulic controls as constraints. The goal of a robust least cost design is to find solutions which guarantee its feasibility independent of the data (i.e., under model uncertainty). A robust counterpart approach for linear uncertain problems is adopted in this study, which represents the uncertain stochastic problem as its deterministic equivalent. Robustness is controlled by a single parameter providing a trade-off between the probability of constraint violation and the objective cost. Two principal models are developed: uncorrelated uncertainty model with implicit design reliability, and correlated uncertainty model with explicit design reliability. The models are tested on three example applications and compared for uncertainty in consumers' demands. The main contribution of this study is the inclusion of the ability to explicitly account for different correlations between water distribution system demand nodes. In particular, it is shown that including correlation information in the design phase has a substantial advantage in seeking more efficient robust solutions.
Robust process design and springback compensation of a decklid inner
NASA Astrophysics Data System (ADS)
Zhang, Xiaojing; Grimm, Peter; Carleer, Bart; Jin, Weimin; Liu, Gang; Cheng, Yingchao
2013-12-01
Springback compensation is one of the key topics in current die face engineering. The accuracy of the springback simulation, the robustness of method planning and springback are considered to be the main factors which influences the effectiveness of springback compensation. In the present paper, the basic principles of springback compensation are presented firstly. These principles consist of an accurate full cycle simulation with final validation setting and the robust process design and optimization are discussed in detail via an industrial example, a decklid inner. Moreover, an effective compensation strategy is put forward based on the analysis of springback and the simulation based springback compensation is introduced in the phase of process design. In the end, the final verification and comparison in tryout and production is given in this paper, which verified that the methodology of robust springback compensation is effective during the die development.
Towards robust optimal design of storm water systems
NASA Astrophysics Data System (ADS)
Marquez Calvo, Oscar; Solomatine, Dimitri
2015-04-01
In this study the focus is on the design of a storm water or a combined sewer system. Such a system should be capable to handle properly most of the storm to minimize the damages caused by flooding due to the lack of capacity of the system to cope with rain water at peak times. This problem is a multi-objective optimization problem: we have to take into account the minimization of the construction costs, the minimization of damage costs due to flooding, and possibly other criteria. One of the most important factors influencing the design of storm water systems is the expected amount of water to deal with. It is common that this infrastructure is developed with the capacity to cope with events that occur once in, say 10 or 20 years - so-called design rainfall events. However, rainfall is a random variable and such uncertainty typically is not taken explicitly into account in optimization. Rainfall design data is based on historical information of rainfalls, but many times this data is based on unreliable measures; or in not enough historical information; or as we know, the patterns of rainfall are changing regardless of historical information. There are also other sources of uncertainty influencing design, for example, leakages in the pipes and accumulation of sediments in pipes. In the context of storm water or combined sewer systems design or rehabilitation, robust optimization technique should be able to find the best design (or rehabilitation plan) within the available budget but taking into account uncertainty in those variables that were used to design the system. In this work we consider various approaches to robust optimization proposed by various authors (Gabrel, Murat, Thiele 2013; Beyer, Sendhoff 2007) and test a novel method ROPAR (Solomatine 2012) to analyze robustness. References Beyer, H.G., & Sendhoff, B. (2007). Robust optimization - A comprehensive survey. Comput. Methods Appl. Mech. Engrg., 3190-3218. Gabrel, V.; Murat, C., Thiele, A. (2014
Robust and versatile software system for optimal design of MEMS structures
NASA Astrophysics Data System (ADS)
Kwak, Byung M.; Lee, Sang H.; Huh, Jae S.
2000-04-01
A CAD-integrated total design system for MEMS is developed which can perform analysis and design for mechanical performance of a MEMS structure. The software works in a parametric CAD platform and makes users to do from CAD modeling and analysis to design optimization. Basic philosophy is to assure robustness, versatility and user friendliness. To satisfy these requirements; 1) Design variables are selectable directly form CAD model, 2) Commercial codes are utilized as many as available, and 3) Design sensitivity analysis must be simple and robust. Commercial finite element codes and some newly developed modules are integrated in the system for analysis. For design sensitivity analysis, two approaches were implemented: finite difference method and the Taguchi method. The approximate methods adopted seem to be simple and robust, which can be applied to design of complex practical structures. The design sensitivity analysis by finite difference method, with nonlinear programming and trade-off study, gives satisfactory results. The Taguchi method module is integrated for robust optimal design of MEMS structure. Although it is not meant to find the exact optimum point, it is applicable to practical problems where performance characteristics are hard to evaluate, since this does not require any derivative information. Two examples are taken to examine performance of the developed design tool and proposed methodology. It relieves much of the difficulties often met in conventional design works and has shown practicability for structural design of MEMS.
Robust, Decoupled, Flight Control Design with Rate Saturating Actuators
NASA Technical Reports Server (NTRS)
Snell, S. A.; Hess, R. A.
1997-01-01
Techniques for the design of control systems for manually controlled, high-performance aircraft must provide the following: (1) multi-input, multi-output (MIMO) solutions, (2) acceptable handling qualities including no tendencies for pilot-induced oscillations, (3) a tractable approach for compensator design, (4) performance and stability robustness in the presence of significant plant uncertainty, and (5) performance and stability robustness in the presence actuator saturation (particularly rate saturation). A design technique built upon Quantitative Feedback Theory is offered as a candidate methodology which can provide flight control systems meeting these requirements, and do so over a considerable part of the flight envelope. An example utilizing a simplified model of a supermaneuverable fighter aircraft demonstrates the proposed design methodology.
Simulation/optimization modeling for robust pumping strategy design.
Kalwij, Ineke M; Peralta, Richard C
2006-01-01
A new simulation/optimization modeling approach is presented for addressing uncertain knowledge of aquifer parameters. The Robustness Enhancing Optimizer (REO) couples genetic algorithm and tabu search as optimizers and incorporates aquifer parameter sensitivity analysis to guide multiple-realization optimization. The REO maximizes strategy robustness for a pumping strategy that is optimal for a primary objective function (OF), such as cost. The more robust a strategy, the more likely it is to achieve management goals in the field, even if the physical system differs from the model. The REO is applied to trinitrotoluene and Royal Demolition Explosive plumes at Umatilla Chemical Depot in Oregon to develop robust least cost strategies. The REO efficiently develops robust pumping strategies while maintaining the optimal value of the primary OF-differing from the common situation in which a primary OF value degrades as strategy reliability increases. The REO is especially valuable where data to develop realistic probability density functions (PDFs) or statistically derived realizations are unavailable. Because they require much less field data, REO-developed strategies might not achieve as high a mathematical reliability as strategies developed using many realizations based upon real aquifer parameter PDFs. REO-developed strategies might or might not yield a better OF value in the field. PMID:16857035
Robust Airfoil Optimization in High Resolution Design Space
NASA Technical Reports Server (NTRS)
Li, Wu; Padula, Sharon L.
2003-01-01
The robust airfoil shape optimization is a direct method for drag reduction over a given range of operating conditions and has three advantages: (1) it prevents severe degradation in the off-design performance by using a smart descent direction in each optimization iteration, (2) it uses a large number of B-spline control points as design variables yet the resulting airfoil shape is fairly smooth, and (3) it allows the user to make a trade-off between the level of optimization and the amount of computing time consumed. The robust optimization method is demonstrated by solving a lift-constrained drag minimization problem for a two-dimensional airfoil in viscous flow with a large number of geometric design variables. Our experience with robust optimization indicates that our strategy produces reasonable airfoil shapes that are similar to the original airfoils, but these new shapes provide drag reduction over the specified range of Mach numbers. We have tested this strategy on a number of advanced airfoil models produced by knowledgeable aerodynamic design team members and found that our strategy produces airfoils better or equal to any designs produced by traditional design methods.
Robustness-Based Design Optimization Under Data Uncertainty
NASA Technical Reports Server (NTRS)
Zaman, Kais; McDonald, Mark; Mahadevan, Sankaran; Green, Lawrence
2010-01-01
This paper proposes formulations and algorithms for design optimization under both aleatory (i.e., natural or physical variability) and epistemic uncertainty (i.e., imprecise probabilistic information), from the perspective of system robustness. The proposed formulations deal with epistemic uncertainty arising from both sparse and interval data without any assumption about the probability distributions of the random variables. A decoupled approach is proposed in this paper to un-nest the robustness-based design from the analysis of non-design epistemic variables to achieve computational efficiency. The proposed methods are illustrated for the upper stage design problem of a two-stage-to-orbit (TSTO) vehicle, where the information on the random design inputs are only available as sparse point and/or interval data. As collecting more data reduces uncertainty but increases cost, the effect of sample size on the optimality and robustness of the solution is also studied. A method is developed to determine the optimal sample size for sparse point data that leads to the solutions of the design problem that are least sensitive to variations in the input random variables.
Optimal Robust Motion Controller Design Using Multiobjective Genetic Algorithm
Svečko, Rajko
2014-01-01
This paper describes the use of a multiobjective genetic algorithm for robust motion controller design. Motion controller structure is based on a disturbance observer in an RIC framework. The RIC approach is presented in the form with internal and external feedback loops, in which an internal disturbance rejection controller and an external performance controller must be synthesised. This paper involves novel objectives for robustness and performance assessments for such an approach. Objective functions for the robustness property of RIC are based on simple even polynomials with nonnegativity conditions. Regional pole placement method is presented with the aims of controllers' structures simplification and their additional arbitrary selection. Regional pole placement involves arbitrary selection of central polynomials for both loops, with additional admissible region of the optimized pole location. Polynomial deviation between selected and optimized polynomials is measured with derived performance objective functions. A multiobjective function is composed of different unrelated criteria such as robust stability, controllers' stability, and time-performance indexes of closed loops. The design of controllers and multiobjective optimization procedure involve a set of the objectives, which are optimized simultaneously with a genetic algorithm—differential evolution. PMID:24987749
Robust design of configurations and parameters of adaptable products
NASA Astrophysics Data System (ADS)
Zhang, Jian; Chen, Yongliang; Xue, Deyi; Gu, Peihua
2014-03-01
An adaptable product can satisfy different customer requirements by changing its configuration and parameter values during the operation stage. Design of adaptable products aims at reducing the environment impact through replacement of multiple different products with single adaptable ones. Due to the complex architecture, multiple functional requirements, and changes of product configurations and parameter values in operation, impact of uncertainties to the functional performance measures needs to be considered in design of adaptable products. In this paper, a robust design approach is introduced to identify the optimal design configuration and parameters of an adaptable product whose functional performance measures are the least sensitive to uncertainties. An adaptable product in this paper is modeled by both configurations and parameters. At the configuration level, methods to model different product configuration candidates in design and different product configuration states in operation to satisfy design requirements are introduced. At the parameter level, four types of product/operating parameters and relations among these parameters are discussed. A two-level optimization approach is developed to identify the optimal design configuration and its parameter values of the adaptable product. A case study is implemented to illustrate the effectiveness of the newly developed robust adaptable design method.
Robust power system controller design based on measured models
Fatehi, F.; Smith, J.R.; Pierre, D.A.
1996-05-01
This paper presents combined system identification and controller design methods to dampen low-frequency oscillations in multimachine power systems. An iterative closed-loop identification method is used to find a linear model for the power system. Linear quadratic Gaussian controller design with loop transfer recovery (LQG/LTR), based on a generalized technique for the nonminimum phase (NMP) power system model, is used to design controllers. Simulation results are presented to demonstrate the robustness of controllers based on closed-loop identified plant models and the amount of loop transfer recovery that is possible for NMP plant models.
Robust co-ordinated AVR-PSS design
Law, K.T.; Hill, D.J. . Dept. of Electrical Engineering and Computer Engineering); Godfrey, N.R. )
1994-08-01
This paper considers the design of auto-voltage regulator (AVR) and power system stabilizer (PSS) for the case of single machine connected to the infinite bus. Although it is not a true representation of the real power system, it is hoped that the insights into the single machine can help in the design of AVR-PSS for multi-machine power systems. The framework of Internal Model Control (IMC) is used to explore the properties and structures of an ideal AVR and an ideal PSS. Although these ideal controllers are not implementable in practice, they provide valuable insights and understanding of the design constraints of the problem which help to lead them to an implementable sub-optimal solution. This resulting AVR-PSS is not only robust but it also allows direct trade-off between voltage regulation and damping performance. The proposed PSS is a merely proportional gain, hence it gives considerable promise for ease of tuning especially in a multimachine system. This paper is a summary of a series of work done on robust co-ordinated AVR-PSS design. In particular, due to limited space, details of robust tuning and analysis techniques will not be presented here.
Robust Control Design for Vibration Isolation of an Electron Beam Projection Lithography System
NASA Astrophysics Data System (ADS)
Wang, Fu-Cheng; Hong, Min-Feng; Yen, Jia-Yush
2010-06-01
This paper describes vibration control for an electron beam projection lithography (EPL) system. Two kinds of disturbances should be considered for an EPL: load disturbances from the machine and ground disturbances from the environment. However, the suspension settings for insulating these two disturbances conflict with each other. Therefore, we propose a double-layer optical table and apply disturbance response decomposing (DRD) techniques to independently control the disturbances. We use a passive control structure to isolate the ground disturbances, and an active control structure to suppress load disturbances. In addition, symmetric transformation is applied to decouple a full optical table into bounce/pitch and roll/warp half-table models, which can be further decoupled into quarter-table models to simplify controller design. Finally, we apply robust control techniques to design active controllers. From both simulation and experimental results, the designed H∞ robust controllers are proven effective in reducing EPL system vibrations.
Robust circuit & architecture design in the nanoscale regime
NASA Astrophysics Data System (ADS)
Ashraf, Rehman
Silicon based integrated circuit (IC) technology is approaching its physical limits. For sub 10nm technology nodes, the carbon nanotube (CNT) based field effect transistor has emerged as a promising device because of its excellent electronic properties. One of the major challenges faced by the CNT technology is the unwanted growth of metallic tubes. At present, there is no known CNT fabrication technology which allows the fabrication of 100% semiconducting CNTs. The presence of metallic tubes creates a short between the drain and source terminals of the transistor and has a detrimental impact on the delay, static power and yield of CNT based gates. This thesis will address the challenge of designing robust carbon nanotube based circuits in the presence of metallic tubes. For a small percentage of metallic tubes, circuit level solutions are proposed to increase the functional yield of CNT based gates in the presence of metallic tubes. Accurate analytical models with less than a 3% inaccuracy rate are developed to estimate the yield of CNT based circuit for a different percentage of metallic tubes and different drive strengths of logic gates. Moreover, a design methodology is developed for yield-aware carbon nanotube based circuits in the presence of metallic tubes using different CNFET transistor configurations. Architecture based on regular logic bricks with underlying hybrid CNFET configurations are developed which gives better trade-offs in terms of performance, power, and functional yield. In the case when the percentage of metallic tubes is large, the proposed circuit level techniques are not sufficient. Extra processing techniques must be applied to remove the metallic tubes. The tube removal techniques have trade-offs, as the removal process is not perfect and removes semiconducting tubes in addition to removing unwanted metallic tubes. As a result, stochastic removal of tubes from the drive and fanout gate(s) results in large variation in the performance of
NASA Technical Reports Server (NTRS)
Murphy, Patrick C.; Davidson, John B.
1998-01-01
A multi-input, multi-output control law design methodology, named "CRAFT", is presented. CRAFT stands for the design objectives addressed, namely, Control power, Robustness, Agility, and Flying Qualities Tradeoffs. The methodology makes use of control law design metrics from each of the four design objective areas. It combines eigenspace assignment, which allows for direct specification of eigenvalues and eigenvectors, with a graphical approach for representing the metrics that captures numerous design goals in one composite illustration. Sensitivity of the metrics to eigenspace choice is clearly displayed, enabling the designer to assess the cost of design tradeoffs. This approach enhances the designer's ability to make informed design tradeoffs and to reach effective final designs. An example of the CRAFT methodology applied to an advanced experimental fighter and discussion of associated design issues are provided.
Frequency domain identification for robust large space structure control design
NASA Technical Reports Server (NTRS)
Yam, Y.; Bayard, D. S.; Scheid, R. E.
1991-01-01
A methodology is demonstrated for frequency domain identification of large space structures which systematically transforms experimental raw data into a form required for synthesizing H(infinity) controllers using modern robust control design software (e.g., Matlab Toolboxes). A unique feature of this approach is that the additive uncertainty is characterized to a specified statistic confidence rather than with hard bounds. In this study, the difference in robust performance is minimal between the two levels of confidence. In general cases, the present methodology provides a tool for performance/confidence level tradeoff studies. For simplicity, the additive uncertainty on a frequency grid is considered and the interpolation error in between grid points is neglected.
Optimal flexible sample size design with robust power.
Zhang, Lanju; Cui, Lu; Yang, Bo
2016-08-30
It is well recognized that sample size determination is challenging because of the uncertainty on the treatment effect size. Several remedies are available in the literature. Group sequential designs start with a sample size based on a conservative (smaller) effect size and allow early stop at interim looks. Sample size re-estimation designs start with a sample size based on an optimistic (larger) effect size and allow sample size increase if the observed effect size is smaller than planned. Different opinions favoring one type over the other exist. We propose an optimal approach using an appropriate optimality criterion to select the best design among all the candidate designs. Our results show that (1) for the same type of designs, for example, group sequential designs, there is room for significant improvement through our optimization approach; (2) optimal promising zone designs appear to have no advantages over optimal group sequential designs; and (3) optimal designs with sample size re-estimation deliver the best adaptive performance. We conclude that to deal with the challenge of sample size determination due to effect size uncertainty, an optimal approach can help to select the best design that provides most robust power across the effect size range of interest. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26999385
Analysis and design of robust decentralized controllers for nonlinear systems
Schoenwald, D.A.
1993-07-01
Decentralized control strategies for nonlinear systems are achieved via feedback linearization techniques. New results on optimization and parameter robustness of non-linear systems are also developed. In addition, parametric uncertainty in large-scale systems is handled by sensitivity analysis and optimal control methods in a completely decentralized framework. This idea is applied to alleviate uncertainty in friction parameters for the gimbal joints on Space Station Freedom. As an example of decentralized nonlinear control, singular perturbation methods and distributed vibration damping are merged into a control strategy for a two-link flexible manipulator.
Robust integrated autopilot/autothrottle design using constrained parameter optimization
NASA Technical Reports Server (NTRS)
Ly, Uy-Loi; Voth, Christopher; Sanjay, Swamy
1990-01-01
A multivariable control design method based on constrained parameter optimization was applied to the design of a multiloop aircraft flight control system. Specifically, the design method is applied to the following: (1) direct synthesis of a multivariable 'inner-loop' feedback control system based on total energy control principles; (2) synthesis of speed/altitude-hold designs as 'outer-loop' feedback/feedforward control systems around the above inner loop; and (3) direct synthesis of a combined 'inner-loop' and 'outer-loop' multivariable control system. The design procedure offers a direct and structured approach for the determination of a set of controller gains that meet design specifications in closed-loop stability, command tracking performance, disturbance rejection, and limits on control activities. The presented approach may be applied to a broader class of multiloop flight control systems. Direct tradeoffs between many real design goals are rendered systematic by this method following careful problem formulation of the design objectives and constraints. Performance characteristics of the optimization design were improved over the current autopilot design on the B737-100 Transport Research Vehicle (TSRV) at the landing approach and cruise flight conditions; particularly in the areas of closed-loop damping, command responses, and control activity in the presence of turbulence.
Designing robust unitary gates: Application to concatenated composite pulses
Ichikawa, Tsubasa; Bando, Masamitsu; Kondo, Yasushi; Nakahara, Mikio
2011-12-15
We propose a simple formalism to design unitary gates robust against given systematic errors. This formalism generalizes our previous observation [Y. Kondo and M. Bando, J. Phys. Soc. Jpn. 80, 054002 (2011)] that vanishing dynamical phase in some composite gates is essential to suppress pulse-length errors. By employing our formalism, we derive a composite unitary gate which can be seen as a concatenation of two known composite unitary operations. The obtained unitary gate has high fidelity over a wider range of error strengths compared to existing composite gates.
Applying Expert System on the Development of a Robust Model for Groundwater Parameter Identification
NASA Astrophysics Data System (ADS)
Hsu, K.; Chang, L.; Jung, C.; Huang, C.; Chen, J.; Tsai, P. J.; Chen, Y.; Chang, P.
2011-12-01
Conventional groundwater parameter identification modeling based on optimization, such as UCODE, has difficulty converging to a global optimum in a high dimension situation. To avoid this convergence problem, this study integrates a rule-based expert system and a groundwater simulation model, MODFLOW 2000, to develop a robust methodology for groundwater parameter identification. Because the expert system requires calibration rules to identify parameters, users can flexibly add new rules or modify existing rules with this proposed methodology. Therefore, the proposed methodology can adapt for new parameter identification problems easily. We apply this proposed methodology to a real case study of Choshuihsi Alluvial Fan which is located at the central Taiwan. To test the robustness for high dimension problems, the proposed methodology is applied to calibrate the net recharge rates in a transient simulation in the study area. The result is compared with the calibration results obtained from UCODE. The results show that the initial guess dramatically effects the convergency of the optimization using UCODE, but our proposed methodology is very robust for achieving the convergence requirements of output error criteria for high dimensional problems. These results presented the robustness and the applicability of the proposed methodology for high dimensional groundwater parameter identification problems.
Quantum theory as plausible reasoning applied to data obtained by robust experiments.
De Raedt, H; Katsnelson, M I; Michielsen, K
2016-05-28
We review recent work that employs the framework of logical inference to establish a bridge between data gathered through experiments and their objective description in terms of human-made concepts. It is shown that logical inference applied to experiments for which the observed events are independent and for which the frequency distribution of these events is robust with respect to small changes of the conditions under which the experiments are carried out yields, without introducing any concept of quantum theory, the quantum theoretical description in terms of the Schrödinger or the Pauli equation, the Stern-Gerlach or Einstein-Podolsky-Rosen-Bohm experiments. The extraordinary descriptive power of quantum theory then follows from the fact that it is plausible reasoning, that is common sense, applied to reproducible and robust experimental data. PMID:27091169
Robust design and model validation of nonlinear compliant micromechanisms.
Howell, Larry L.; Baker, Michael Sean; Wittwer, Jonathan W.
2005-02-01
Although the use of compliance or elastic flexibility in microelectromechanical systems (MEMS) helps eliminate friction, wear, and backlash, compliant MEMS are known to be sensitive to variations in material properties and feature geometry, resulting in large uncertainties in performance. This paper proposes an approach for design stage uncertainty analysis, model validation, and robust optimization of nonlinear MEMS to account for critical process uncertainties including residual stress, layer thicknesses, edge bias, and material stiffness. A fully compliant bistable micromechanism (FCBM) is used as an example, demonstrating that the approach can be used to handle complex devices involving nonlinear finite element models. The general shape of the force-displacement curve is validated by comparing the uncertainty predictions to measurements obtained from in situ force gauges. A robust design is presented, where simulations show that the estimated force variation at the point of interest may be reduced from {+-}47 {micro}N to {+-}3 {micro}N. The reduced sensitivity to process variations is experimentally validated by measuring the second stable position at multiple locations on a wafer.
A robust adaptive autopilot design for decomposed bank to turn missiles
NASA Astrophysics Data System (ADS)
Song, Kwang Sub
2001-07-01
A decomposed robust adaptive controller design procedure is developed for 3-channel BTT missile systems. Three decomposed subsystems are constructed for highly nonlinear and coupled dynamic systems after parameter analysis is carried out. Appropriate adaptive optimal inner loop controllers are designed for accurate tracking performance to the reference command inputs of the respective subsystems. For robustness of systems, decomposed outer loop structures are introduced to minimize system coupling and to reduce nonlinear effects of BTT missile dynamic systems. The overall outer loop robust controller is designed to accommodate parameter variations and uncertainties with referenced model systems. The robust outer loop controller is designed by constructing decomposed stabilizing controllers in the form of the Youla parameterization. The results can be readily generalized to N-channel systems. The design procedure is built upon the J-spectral factorization approach to Hinfinity control. Instead of the centralized control, we employed decentralized controllers for reduced complexity in control implementations. In this research, a new concept for system modeling and decomposition, which uses the rate of system dynamics or the sensitivity of system parameter. After exhaustive classification and investigations of system characteristics, we can categorize several subsystems from overall system dynamic models. Subsystems are characterized by system dynamics with similar rates of changes. Once we get relatively small sized and homogeneous parameter groups, it is easier to design respective controllers. Otherwise, difficult trade offs must be made on control objectives for different kinds of dynamic characteristics of the whole system. The new idea is applied to a typical BTT missile system. Simulations results demonstrate that decomposed controller design is satisfactory for the BTT missile autopilot systems with good robustness and dynamic performances.
Preliminary demonstration of a robust controller design method
NASA Technical Reports Server (NTRS)
Anderson, L. R.
1980-01-01
Alternative computational procedures for obtaining a feedback control law which yields a control signal based on measurable quantitites are evaluated. The three methods evaluated are: (1) the standard linear quadratic regulator design model; (2) minimization of the norm of the feedback matrix, k via nonlinear programming subject to the constraint that the closed loop eigenvalues be in a specified domain in the complex plane; and (3) maximize the angles between the closed loop eigenvectors in combination with minimizing the norm of K also via the constrained nonlinear programming. The third or robust design method was chosen to yield a closed loop system whose eigenvalues are insensitive to small changes in the A and B matrices. The relationship between orthogonality of closed loop eigenvectors and the sensitivity of closed loop eigenvalues is described. Computer programs are described.
Robust Feedback Linearization Applied to a Separation Column for {sup 13}C
Dulf, Eva-Henrietta; Pop, Cristina-Ioana; Festila, Clement; Dulf, Francisc
2009-03-05
In the present developing plan to apply the cryogenic technology for the production of the {sup 13}C, an efficient and safe operation is a strong reason to conceive and to apply a modern computer based control strategy. The authors are concerned with the problem of developing effective and readily implemental techniques for modelling and control of the isotope separation plant. These columns are characterized by complex nonlinearities, with large time-delays. Furthermore, are subject to external disturbances, which are difficult to model. The present paper presents two models of the plant: a nonlinear model and a linear system obtained by robust feedback linearization.
Lin, Yuqun
2014-01-01
The performance of the suspension system is one of the most important factors in the vehicle design. For the double wishbone suspension system, the conventional deterministic optimization does not consider any deviations of design parameters, so design sensitivity analysis and robust optimization design are proposed. In this study, the design parameters of the robust optimization are the positions of the key points, and the random factors are the uncertainties in manufacturing. A simplified model of the double wishbone suspension is established by software ADAMS. The sensitivity analysis is utilized to determine main design variables. Then, the simulation experiment is arranged and the Latin hypercube design is adopted to find the initial points. The Kriging model is employed for fitting the mean and variance of the quality characteristics according to the simulation results. Further, a particle swarm optimization method based on simple PSO is applied and the tradeoff between the mean and deviation of performance is made to solve the robust optimization problem of the double wishbone suspension system. PMID:24683334
Robust parameter design for automatically controlled systems and nanostructure synthesis
NASA Astrophysics Data System (ADS)
Dasgupta, Tirthankar
2007-12-01
This research focuses on developing comprehensive frameworks for developing robust parameter design methodology for dynamic systems with automatic control and for synthesis of nanostructures. In many automatically controlled dynamic processes, the optimal feedback control law depends on the parameter design solution and vice versa and therefore an integrated approach is necessary. A parameter design methodology in the presence of feedback control is developed for processes of long duration under the assumption that experimental noise factors are uncorrelated over time. Systems that follow a pure-gain dynamic model are considered and the best proportional-integral and minimum mean squared error control strategies are developed by using robust parameter design. The proposed method is illustrated using a simulated example and a case study in a urea packing plant. This idea is also extended to cases with on-line noise factors. The possibility of integrating feedforward control with a minimum mean squared error feedback control scheme is explored. To meet the needs of large scale synthesis of nanostructures, it is critical to systematically find experimental conditions under which the desired nanostructures are synthesized reproducibly, at large quantity and with controlled morphology. The first part of the research in this area focuses on modeling and optimization of existing experimental data. Through a rigorous statistical analysis of experimental data, models linking the probabilities of obtaining specific morphologies to the process variables are developed. A new iterative algorithm for fitting a Multinomial GLM is proposed and used. The optimum process conditions, which maximize the above probabilities and make the synthesis process less sensitive to variations of process variables around set values, are derived from the fitted models using Monte-Carlo simulations. The second part of the research deals with development of an experimental design methodology, tailor
Advanced Vibration Analysis Tool Developed for Robust Engine Rotor Designs
NASA Technical Reports Server (NTRS)
Min, James B.
2005-01-01
The primary objective of this research program is to develop vibration analysis tools, design tools, and design strategies to significantly improve the safety and robustness of turbine engine rotors. Bladed disks in turbine engines always feature small, random blade-to-blade differences, or mistuning. Mistuning can lead to a dramatic increase in blade forced-response amplitudes and stresses. Ultimately, this results in high-cycle fatigue, which is a major safety and cost concern. In this research program, the necessary steps will be taken to transform a state-of-the-art vibration analysis tool, the Turbo- Reduce forced-response prediction code, into an effective design tool by enhancing and extending the underlying modeling and analysis methods. Furthermore, novel techniques will be developed to assess the safety of a given design. In particular, a procedure will be established for using natural-frequency curve veerings to identify ranges of operating conditions (rotational speeds and engine orders) in which there is a great risk that the rotor blades will suffer high stresses. This work also will aid statistical studies of the forced response by reducing the necessary number of simulations. Finally, new strategies for improving the design of rotors will be pursued.
A robust parameter design for multi-response problems
NASA Astrophysics Data System (ADS)
Zandieh, M.; Amiri, M.; Vahdani, B.; Soltani, R.
2009-08-01
Most real world search and optimization problems naturally involve multiple responses. In this paper we investigate a multiple response problem within desirability function framework and try to determine values of input variables that achieve a target value for each response through three meta-heuristic algorithms such as genetic algorithm (GA), simulated annealing (SA) and tabu search (TS). Each algorithm has some parameters that need to be accurately calibrated to ensure the best performance. For this purpose, a robust calibration is applied to the parameters by means of Taguchi method. The computational results of these three algorithms are compared against each others. The superior performance of SA over TS and TS over GA is inferred from the obtained results in various situations.
Sliding-Mode Control Applied for Robust Control of a Highly Unstable Aircraft
NASA Technical Reports Server (NTRS)
Vetter, Travis Kenneth
2002-01-01
An investigation into the application of an observer based sliding mode controller for robust control of a highly unstable aircraft and methods of compensating for actuator dynamics is performed. After a brief overview of some reconfigurable controllers, sliding mode control (SMC) is selected because of its invariance properties and lack of need for parameter identification. SMC is reviewed and issues with parasitic dynamics, which cause system instability, are addressed. Utilizing sliding manifold boundary layers, the nonlinear control is converted to a linear control and sliding manifold design is performed in the frequency domain. An additional feedback form of model reference hedging is employed which is similar to a prefilter and has large benefits to system performance. The effects of inclusion of actuator dynamics into the designed plant is heavily investigated. Multiple Simulink models of the full longitudinal dynamics and wing deflection modes of the forward swept aero elastic vehicle (FSAV) are constructed. Additionally a linear state space models to analyze effects from various system parameters. The FSAV has a pole at +7 rad/sec and is non-minimum phase. The use of 'model actuators' in the feedback path, and varying there design, is heavily investigated for the resulting effects on plant robustness and tolerance to actuator failure. The use of redundant actuators is also explored and improved robustness is shown. All models are simulated with severe failure and excellent tracking, and task dependent handling qualities, and low pilot induced oscillation tendency is shown.
Efficiency and robustness of different bus network designs
NASA Astrophysics Data System (ADS)
Pang, John Zhen Fu; Bin Othman, Nasri; Ng, Keng Meng; Monterola, Christopher
2015-07-01
We compare the efficiencies and robustness of four transport networks that can be possibly formed as a result of deliberate city planning. The networks are constructed based on their spatial resemblance to the cities of Manhattan (lattice), Sudan (random), Beijing (single-blob) and Greater Cairo (dual-blob). For a given type, a genetic algorithm is employed to obtain an optimized set of the bus routes. We then simulate how commuter travels using Yen's algorithms for k shortest paths on an adjacency matrix. The cost of traveling such as walking between stations is captured by varying the weighted sums of matrices. We also consider the number of transfers a posteriori by looking at the computed shortest paths. With consideration to distances via radius of gyration, redundancies of travel and number of bus transfers, our simulations indicate that random and dual-blob are more efficient than single-blob and lattice networks. Moreover, dual-blob type is least robust when node removals are targeted but is most resilient when node failures are random. The work hopes to guide and provide technical perspectives on how geospatial distribution of a city limits the optimality of transport designs.
Robustness in Nature as a Design Principle for Artificial Intelligence
NASA Astrophysics Data System (ADS)
Schuster, Alfons
Robustness is a feature in many systems, natural and artificial alike. This chapter investigates robustness from a variety of perspectives including its appearances in nature and its application in modern environments. A particular focus investigates the relevance and importance of robustness in a discipline where many techniques are inspired by problem-solving strategies found in nature—artificial intelligence. The challenging field of artificial intelligence provides an opportunity to engage in a wider discussion on the subject of robustness.
Robust Optimization Design Algorithm for High-Frequency TWTs
NASA Technical Reports Server (NTRS)
Wilson, Jeffrey D.; Chevalier, Christine T.
2010-01-01
Traveling-wave tubes (TWTs), such as the Ka-band (26-GHz) model recently developed for the Lunar Reconnaissance Orbiter, are essential as communication amplifiers in spacecraft for virtually all near- and deep-space missions. This innovation is a computational design algorithm that, for the first time, optimizes the efficiency and output power of a TWT while taking into account the effects of dimensional tolerance variations. Because they are primary power consumers and power generation is very expensive in space, much effort has been exerted over the last 30 years to increase the power efficiency of TWTs. However, at frequencies higher than about 60 GHz, efficiencies of TWTs are still quite low. A major reason is that at higher frequencies, dimensional tolerance variations from conventional micromachining techniques become relatively large with respect to the circuit dimensions. When this is the case, conventional design- optimization procedures, which ignore dimensional variations, provide inaccurate designs for which the actual amplifier performance substantially under-performs that of the design. Thus, this new, robust TWT optimization design algorithm was created to take account of and ameliorate the deleterious effects of dimensional variations and to increase efficiency, power, and yield of high-frequency TWTs. This design algorithm can help extend the use of TWTs into the terahertz frequency regime of 300-3000 GHz. Currently, these frequencies are under-utilized because of the lack of efficient amplifiers, thus this regime is known as the "terahertz gap." The development of an efficient terahertz TWT amplifier could enable breakthrough applications in space science molecular spectroscopy, remote sensing, nondestructive testing, high-resolution "through-the-wall" imaging, biomedical imaging, and detection of explosives and toxic biochemical agents.
Salinas, Cristian; Muzic, Raymond F. Jr.; Ernsberger, Paul; Saidel, Gerald M.
2007-01-15
Myocardial {beta} adrenergic receptor ({beta}-AR) concentration can substantially decrease in congestive heart failure and significantly increase in chronic volume overload, such as in severe aortic valve regurgitation. Positron emission tomography (PET) with an appropriate ligand-receptor model can be used for noninvasive estimation of myocardial {beta}-AR concentration in vivo. An optimal design of the experiment protocol, however, is needed for sufficiently precise estimates of {beta}-AR concentration in a heterogeneous population. Standard methods of optimal design do not account for a heterogeneous population with a wide range of {beta}-AR concentrations and other physiological parameters and consequently are inadequate. To address this, we have developed a methodology to design a robust two-injection protocol that provides reliable estimates of myocardial {beta}-AR concentration in normal and pathologic states. A two-injection protocol of the high affinity {beta}-AR antagonist [{sup 18}F]-(S)-fluorocarazolol was designed based on a computer-generated (or synthetic) population incorporating a wide range of {beta}-AR concentrations. Timing and dosage of the ligand injections were optimally designed with minimax criterion to provide the least bad {beta}-AR estimates for the worst case in the synthetic population. This robust experiment design for PET was applied to experiments with pigs before and after {beta}-AR upregulation by chemical sympathectomy. Estimates of {beta}-AR concentration were found by minimizing the difference between the model-predicted and experimental PET data. With this robust protocol, estimates of {beta}-AR concentration showed high precision in both normal and pathologic states. The increase in {beta}-AR concentration after sympathectomy predicted noninvasively with PET is consistent with the increase shown by in vitro assays in pig myocardium. A robust experiment protocol was designed for PET that yields reliable estimates of {beta
Intergration of system identification and robust controller designs for flexible structures in space
NASA Technical Reports Server (NTRS)
Juang, Jer-Nan; Lew, Jiann-Shiun
1990-01-01
An approach is developed using experimental data to identify a reduced-order model and its model error for a robust controller design. There are three steps involved in the approach. First, an approximately balanced model is identified using the Eigensystem Realization Algorithm, which is an identification algorithm. Second, the model error is calculated and described in frequency domain in terms of the H(infinity) norm. Third, a pole placement technique in combination with a H(infinity) control method is applied to design a controller for the considered system. A set experimental data from an existing setup, namely the Mini-Mast system, is used to illustrate and verify the approach.
Design of a robust SHM system for composite structures
NASA Astrophysics Data System (ADS)
Beard, Shawn; Liu, Ching-Chao; Chang, Fu-Kuo
2007-04-01
Composites are becoming increasingly popular materials used in a wide range of applications on large-scale structures such as windmill blades, rocket motor cases, and aircraft fuselage and wings. For these large structures, using composites greatly enhances the operation and performance of the application, but also introduces extraordinary inspection challenges that push the limits of traditional NDE in terms of time and cost. Recent advances in Structural Health Monitoring (SHM) technologies offer a promising solution to these inspection challenges. But efficient design methodologies and implementation procedures are needed to ensure the reliability and robustness of SHM technologies for use in real-world applications. This paper introduces the essential elements of the design and implementation process by way of example. State-of-the-art techniques to optimize sensor placement, perform self-diagnostics, compensate for environmental conditions, and generate probability of detection (POD) curves for any application are discussed. The techniques are presented in relation to Acellent's recently developed SmartComposite System that is used to monitor the integrity of large composite structures. The system builds on the active sensor network technology of Acellent that is analogous to a built-in acousto-ultrasonic NDE system. Key features of the system include new miniaturized lightweight hardware, self-diagnostics and adaptive algorithm to automatically compensate for damaged sensors, reliable damage detection under different environmental conditions, and generation of POD curves. This paper will provide an overview of the system and demonstrate its key features.
Sliding Mode Control Applied to Reconfigurable Flight Control Design
NASA Technical Reports Server (NTRS)
Hess, R. A.; Wells, S. R.; Bacon, Barton (Technical Monitor)
2002-01-01
Sliding mode control is applied to the design of a flight control system capable of operating with limited bandwidth actuators and in the presence of significant damage to the airframe and/or control effector actuators. Although inherently robust, sliding mode control algorithms have been hampered by their sensitivity to the effects of parasitic unmodeled dynamics, such as those associated with actuators and structural modes. It is known that asymptotic observers can alleviate this sensitivity while still allowing the system to exhibit significant robustness. This approach is demonstrated. The selection of the sliding manifold as well as the interpretation of the linear design that results after introduction of a boundary layer is accomplished in the frequency domain. The design technique is exercised on a pitch-axis controller for a simple short-period model of the High Angle of Attack F-18 vehicle via computer simulation. Stability and performance is compared to that of a system incorporating a controller designed by classical loop-shaping techniques.
Designing for Damage: Robust Flight Control Design using Sliding Mode Techniques
NASA Technical Reports Server (NTRS)
Vetter, T. K.; Wells, S. R.; Hess, Ronald A.; Bacon, Barton (Technical Monitor); Davidson, John (Technical Monitor)
2002-01-01
A brief review of sliding model control is undertaken, with particular emphasis upon the effects of neglected parasitic dynamics. Sliding model control design is interpreted in the frequency domain. The inclusion of asymptotic observers and control 'hedging' is shown to reduce the effects of neglected parasitic dynamics. An investigation into the application of observer-based sliding mode control to the robust longitudinal control of a highly unstable is described. The sliding mode controller is shown to exhibit stability and performance robustness superior to that of a classical loop-shaped design when significant changes in vehicle and actuator dynamics are employed to model airframe damage.
A novel methodology for building robust design rules by using design based metrology (DBM)
NASA Astrophysics Data System (ADS)
Lee, Myeongdong; Choi, Seiryung; Choi, Jinwoo; Kim, Jeahyun; Sung, Hyunju; Yeo, Hyunyoung; Shim, Myoungseob; Jin, Gyoyoung; Chung, Eunseung; Roh, Yonghan
2013-03-01
This paper addresses a methodology for building robust design rules by using design based metrology (DBM). Conventional method for building design rules has been using a simulation tool and a simple pattern spider mask. At the early stage of the device, the estimation of simulation tool is poor. And the evaluation of the simple pattern spider mask is rather subjective because it depends on the experiential judgment of an engineer. In this work, we designed a huge number of pattern situations including various 1D and 2D design structures. In order to overcome the difficulties of inspecting many types of patterns, we introduced Design Based Metrology (DBM) of Nano Geometry Research, Inc. And those mass patterns could be inspected at a fast speed with DBM. We also carried out quantitative analysis on PWQ silicon data to estimate process variability. Our methodology demonstrates high speed and accuracy for building design rules. All of test patterns were inspected within a few hours. Mass silicon data were handled with not personal decision but statistical processing. From the results, robust design rules are successfully verified and extracted. Finally we found out that our methodology is appropriate for building robust design rules.
Robustness analysis and controller design for static var compensators in power systems
NASA Astrophysics Data System (ADS)
Yu, Xuechun I.
effect of the supplementary controller on improving system dynamic performance and stability limits is also examined. The technique is applied to two test systems which are the four-machine test system and the IEEE 50-generator test system. Both the analysis and synthesis results clearly demonstrate the efficacy of the mu-based technique in analyzing and designing controls to meet robust performance and stability requirement.
Robust Engineering Designs for Infrastructure Adaptation to a Changing Climate
NASA Astrophysics Data System (ADS)
Samaras, C.; Cook, L.
2015-12-01
Infrastructure systems are expected to be functional, durable and safe over long service lives - 50 to over 100 years. Observations and models of climate science show that greenhouse gas emissions resulting from human activities have changed climate, weather and extreme events. Projections of future changes (albeit with uncertainties caused by inadequacies of current climate/weather models) can be made based on scenarios for future emissions, but actual future emissions are themselves uncertain. Most current engineering standards and practices for infrastructure assume that the probabilities of future extreme climate and weather events will match those of the past. Climate science shows that this assumption is invalid, but is unable, at present, to define these probabilities over the service lives of existing and new infrastructure systems. Engineering designs, plans, and institutions and regulations will need to be adaptable for a range of future conditions (conditions of climate, weather and extreme events, as well as changing societal demands for infrastructure services). For their current and future projects, engineers should: Involve all stakeholders (owners, financers, insurance, regulators, affected public, climate/weather scientists, etc.) in key decisions; Use low regret, adaptive strategies, such as robust decision making and the observational method, comply with relevant standards and regulations, and exceed their requirements where appropriate; Publish design studies and performance/failure investigations to extend the body of knowledge for advancement of practice. The engineering community should conduct observational and modeling research with climate/weather/social scientists and the concerned communities and account rationally for climate change in revised engineering standards and codes. This presentation presents initial research on decisionmaking under uncertainty for climate resilient infrastructure design.
Robust two-parameter invariant CFAR detection utilizing order statistics applied to Weibull clutter
NASA Astrophysics Data System (ADS)
Nagle, Daniel T.; Saniie, Jafar
1992-08-01
Constant False Alarm Rate (CFAR) detectors are designed to perform when the clutter information is partially unknown and/or varying. This is accomplished using local threshold estimates from background observations in which the CFAR level is maintained. However, when local observations contain target or irrelevant information, censoring is warranted to improve detection performance. Order Statistics (OS) processors have been shown to perform robustly (referring to type II errors or CFAR loss) for heterogeneous background clutter observations, and their performance has been analyzed for exponential clutter with unknown power. In this paper, several order statistics are used to create an invariant test statistic for Weibull clutter with two varying parameters (i.e., power and skewness). The robustness of a two-parameter invariant CFAR detector is analyzed and compared with an uncensored Weibull-Two Parameter (WTP) CFAR detector and conventional Cell Averaging (CA)-CFAR detector (i.e., designed invariant to exponential clutter). The performance trade-offs of these detectors are gaged for different scenarios of volatile clutter environments.
Robust Stability Analysis of the Space Launch System Control Design: A Singular Value Approach
NASA Technical Reports Server (NTRS)
Pei, Jing; Newsome, Jerry R.
2015-01-01
Classical stability analysis consists of breaking the feedback loops one at a time and determining separately how much gain or phase variations would destabilize the stable nominal feedback system. For typical launch vehicle control design, classical control techniques are generally employed. In addition to stability margins, frequency domain Monte Carlo methods are used to evaluate the robustness of the design. However, such techniques were developed for Single-Input-Single-Output (SISO) systems and do not take into consideration the off-diagonal terms in the transfer function matrix of Multi-Input-Multi-Output (MIMO) systems. Robust stability analysis techniques such as H(sub infinity) and mu are applicable to MIMO systems but have not been adopted as standard practices within the launch vehicle controls community. This paper took advantage of a simple singular-value-based MIMO stability margin evaluation method based on work done by Mukhopadhyay and Newsom and applied it to the SLS high-fidelity dynamics model. The method computes a simultaneous multi-loop gain and phase margin that could be related back to classical margins. The results presented in this paper suggest that for the SLS system, traditional SISO stability margins are similar to the MIMO margins. This additional level of verification provides confidence in the robustness of the control design.
Applying vision feedback to crane controller design
NASA Astrophysics Data System (ADS)
Lee, Lun-Hui; Huang, Pei-Hsiang; Pan, Shing-Tai; Wijaya Lie, Handra; Chiang, Tung-Chien; Chang, Cheng-Yuan
2015-01-01
Encoders are generally used to track the motion of industrial mechanisms. However, the information obtained by encoders may have errors due to encoder aging or mechanism-design problem. Therefore, information by visual feedback is a better way to track the movement of industrial mechanisms. However, image information costs lots of computing effort so it is not easy to be used in real-time control applications. This manuscript derives a simple but effective visual feedback method to follow the target and the image information is obtained only by a general handy camcorder. Besides, the proposed method can track multi-locations in a meantime. Fast image pattern recognition and localisation of the colour histogram by using a moving tracking block is applied to increase the calculation speed. Finally, the obtained locations information by the proposed visual feedback method is applied in an industrial crane control system to verify the effectiveness.
Robust controller design of four wheel steering systems using mu synthesis techniques
Gao, X.; McVey, B.D.; Tokar, R.L.
1995-02-27
In this paper, a linearized four wheel steering (4WS) system model is deduced and then modified into a form which is appropriate for applying Matlab {mu} Toolbox to design robust controller. Several important topics are discussed in detail, such as (1) how to make system set-up match Matlab {mu} Toolbox requirement, (2) how to select weights based on plant`s uncertainty, (3) how to solve controller discretization problem, and (4) how to adjust the system so that the conditions necessary for using a state-space formula to solve H{infinity} optimal (sub-optimal) problem and performing the Matlab {mu} Toolbox D--K iteration procedure are satisfied. Finally simulation results of robust controller and a PID controller are compared.
Design of robust controllers for smart structural systems with structured uncertainties
NASA Astrophysics Data System (ADS)
Sana, Sridhar; Rao, Vittal S.
2000-06-01
Effective integration of sensors, actuators and controllers with the structures is key to the success of smart structures. This concept has been manifested in numerous applications of smart structures in the areas such as civil, aerospace and automotive engineering. Control systems to be integrated with the structure is of paramount importance for ensuring the performance requirements in the presence of modal parameter variations, modeling errors and control effort constraints. The primary uncertainty associated with smart structural systems use the natural frequency variations. Linear Matrix Inequalities (LMIs) can be utilized to incorporate the real parameter uncertainty due to parameter variations and control input limits in the controller design. One of the challenges in the design of such controllers is the conservatism due to over bounding effect from the multiple constraints. Additional conservatism can also come from the approximation of the real parametric uncertainty due to modal parameter variations as sector bounded nonlinear, time varying or complex valued uncertainty. Using the traditional robustness analysis methods such as small gain theorem in the controller design will result in conservative designs leading to poor performance. In this paper, we present a controller synthesis procedure based on Popov stability results for reducing the conservatism in the design. Robust controllers are designed for real- parametric uncertainty arising from natural frequency variations in the presence of control input limits. Maximum possible attenuation in the structural response due to finite energy disturbances is also achieved. Trade-off between the robustness versus the control input limit is discussed. The design procedure is applied on a smart structural test article and the results are presented.
Design and Evaluation of a Robust PID Controller for a Fully Implantable Artificial Pancreas
2015-01-01
Treatment of type 1 diabetes mellitus could be greatly improved by applying a closed-loop control strategy to insulin delivery, also known as an artificial pancreas (AP). In this work, we outline the design of a fully implantable AP using intraperitoneal (IP) insulin delivery and glucose sensing. The design process utilizes the rapid glucose sensing and insulin action offered by the IP space to tune a PID controller with insulin feedback to provide safe and effective insulin delivery. The controller was tuned to meet robust performance and stability specifications. An anti-reset windup strategy was introduced to prevent dangerous undershoot toward hypoglycemia after a large meal disturbance. The final controller design achieved 78% of time within the tight glycemic range of 80–140 mg/dL, with no time spent in hypoglycemia. The next step is to test this controller design in an animal model to evaluate the in vivo performance. PMID:26538805
A design methodology for robust failure detection and isolation
NASA Technical Reports Server (NTRS)
Pattipati, K. R.; Willsky, A. S.; Deckert, J. C.; Eterno, J. S.; Weiss, J. S.
1984-01-01
A decentralized failure detection and isolation (FDI) methodology, which is robust with respect to model uncertainties and noise, is presented Redundancy metrics are developed, and optimization problems are posed for the choices of robust parity relations. Closed-form solutions for some special failure cases are given. Connections are drawn with other disciplines, and the use of the metrics to evaluate alternative FDI schemes is discussed.
Design of a robust EMG sensing interface for pattern classification.
Huang, He; Zhang, Fan; Sun, Yan L; He, Haibo
2010-10-01
Electromyographic (EMG) pattern classification has been widely investigated for neural control of external devices in order to assist with movements of patients with motor deficits. Classification performance deteriorates due to inevitable disturbances to the sensor interface, which significantly challenges the clinical value of this technique. This study aimed to design a sensor fault detection (SFD) module in the sensor interface to provide reliable EMG pattern classification. This module monitored the recorded signals from individual EMG electrodes and performed a self-recovery strategy to recover the classification performance when one or more sensors were disturbed. To evaluate this design, we applied synthetic disturbances to EMG signals collected from leg muscles of able-bodied subjects and a subject with a transfemoral amputation and compared the accuracies for classifying transitions between different locomotion modes with and without the SFD module. The results showed that the SFD module maintained classification performance when one signal was distorted and recovered about 20% of classification accuracy when four signals were distorted simultaneously. The method was simple to implement. Additionally, these outcomes were observed for all subjects, including the leg amputee, which implies the promise of the designed sensor interface for providing a reliable neural-machine interface for artificial legs. PMID:20811091
Design of a robust EMG sensing interface for pattern classification
NASA Astrophysics Data System (ADS)
Huang, He; Zhang, Fan; Sun, Yan L.; He, Haibo
2010-10-01
Electromyographic (EMG) pattern classification has been widely investigated for neural control of external devices in order to assist with movements of patients with motor deficits. Classification performance deteriorates due to inevitable disturbances to the sensor interface, which significantly challenges the clinical value of this technique. This study aimed to design a sensor fault detection (SFD) module in the sensor interface to provide reliable EMG pattern classification. This module monitored the recorded signals from individual EMG electrodes and performed a self-recovery strategy to recover the classification performance when one or more sensors were disturbed. To evaluate this design, we applied synthetic disturbances to EMG signals collected from leg muscles of able-bodied subjects and a subject with a transfemoral amputation and compared the accuracies for classifying transitions between different locomotion modes with and without the SFD module. The results showed that the SFD module maintained classification performance when one signal was distorted and recovered about 20% of classification accuracy when four signals were distorted simultaneously. The method was simple to implement. Additionally, these outcomes were observed for all subjects, including the leg amputee, which implies the promise of the designed sensor interface for providing a reliable neural-machine interface for artificial legs.
Design of a robust EMG sensing interface for pattern classification
Huang, He; Zhang, Fan; Sun, Yan L.; He, Haibo
2010-01-01
Electromyographic (EMG) pattern classification has been widely investigated for neural control of external devices in order to assist with movements of patients with motor deficits. Classification performance deteriorates due to inevitable disturbances to the sensor interface, which significantly challenges the clinical value of this technique. This study aimed to design a sensor fault detection (SFD) module in the sensor interface to provide reliable EMG pattern classification. This module monitored the recorded signals from individual EMG electrodes and performed a self-recovery strategy to recover the classification performance when one or more sensors were disturbed. To evaluate this design, we applied synthetic disturbances to EMG signals collected from leg muscles of able-bodied subjects and a subject with a transfemoral amputation and compared the accuracies for classifying transitions between different locomotion modes with and without the SFD module. The results showed that the SFD module maintained classification performance when one signal was distorted and recovered about 20% of classification accuracy when four signals were distorted simultaneously. The method was simple to implement. Additionally, these outcomes were observed for all subjects, including the leg amputee, which implies the promise of the designed sensor interface for providing a reliable neural-machine interface for artificial legs. PMID:20811091
Reducing Design Risk Using Robust Design Methods: A Dual Response Surface Approach
NASA Technical Reports Server (NTRS)
Unal, Resit; Yeniay, Ozgur; Lepsch, Roger A. (Technical Monitor)
2003-01-01
Space transportation system conceptual design is a multidisciplinary process containing considerable element of risk. Risk here is defined as the variability in the estimated (output) performance characteristic of interest resulting from the uncertainties in the values of several disciplinary design and/or operational parameters. Uncertainties from one discipline (and/or subsystem) may propagate to another, through linking parameters and the final system output may have a significant accumulation of risk. This variability can result in significant deviations from the expected performance. Therefore, an estimate of variability (which is called design risk in this study) together with the expected performance characteristic value (e.g. mean empty weight) is necessary for multidisciplinary optimization for a robust design. Robust design in this study is defined as a solution that minimizes variability subject to a constraint on mean performance characteristics. Even though multidisciplinary design optimization has gained wide attention and applications, the treatment of uncertainties to quantify and analyze design risk has received little attention. This research effort explores the dual response surface approach to quantify variability (risk) in critical performance characteristics (such as weight) during conceptual design.
Student design projects in applied acoustics.
Bös, Joachim; Moritz, Karsten; Skowronek, Adam; Thyes, Christian; Tschesche, Johannes; Hanselka, Holger
2012-03-01
This paper describes a series of student projects which are intended to complement theoretical education in acoustics and engineering noise control with practical experience. The projects are also intended to enhance the students' ability to work in a team, to manage a project, and to present their results. The projects are carried out in close cooperation with industrial partners so that the students can get a taste of the professional life of noise control engineers. The organization of such a project, its execution, and some of the results from the most recent student project are presented as a demonstrative example. This latest project involved the creation of noise maps of a production hall, the acoustic analysis of a packaging machine, and the acoustic analysis of a spiral vibratory conveyor. Upon completion of the analysis, students then designed, applied, and verified some simple preliminary noise reduction measures to demonstrate the potential of these techniques. PMID:22423803
Ignition target design and robustness studies for the National Ignition Facility
Krauser, W.J.; Hoffman, N.M.; Wilson, D.C.
1995-12-01
Recent results are presented from two-dimensional LASNEX calculations of the indirectly driven hohlraum and ignition capsules proposed for the National Ignition Facility (NIF). The calculations concentrate on two capsule designs, the baseline design which has a bromine-doped plastic ablator, and the beryllium design which has a copper-doped beryllium ablator. Both capsules have a cryogenic fuel layer. Primary emphasis in these calculations is placed upon robustness studies detailing various sensitivities. These studies fall naturally into two categories, those performed with integrated modeling where the capsule, hohlraum, and laser rays all are modeled simultaneously with the laser power levels as the only energy input, and those performed in a capsule-only mode where an externally imposed drive is applied to the exterior of the ignition capsule and only the capsule performance is modeled. Integrated modeling calculations address sensitivities to, e.g., the laser pointing; among other things, capsule-only calculations address yield degradation due to the growth of hydrodynamic instabilities seeded by initial surface roughnesses on the capsules. Limitations of the calculational models and directions for future research are discussed. The results of the robustness studies performed to date enhance the authors` confidence that the NIF can achieve ignition and produce 10--15 MJ of capsule yield with one or more capsule designs.
Simulation Assisted Risk Assessment Applied to Launch Vehicle Conceptual Design
NASA Technical Reports Server (NTRS)
Mathias, Donovan L.; Go, Susie; Gee, Ken; Lawrence, Scott
2008-01-01
A simulation-based risk assessment approach is presented and is applied to the analysis of abort during the ascent phase of a space exploration mission. The approach utilizes groupings of launch vehicle failures, referred to as failure bins, which are mapped to corresponding failure environments. Physical models are used to characterize the failure environments in terms of the risk due to blast overpressure, resulting debris field, and the thermal radiation due to a fireball. The resulting risk to the crew is dynamically modeled by combining the likelihood of each failure, the severity of the failure environments as a function of initiator and time of the failure, the robustness of the crew module, and the warning time available due to early detection. The approach is shown to support the launch vehicle design process by characterizing the risk drivers and identifying regions where failure detection would significantly reduce the risk to the crew.
NASA Astrophysics Data System (ADS)
Martowicz, Adam; Uhl, Tadeusz
2012-10-01
The paper discusses the applicability of a reliability- and performance-based multi-criteria robust design optimization technique for micro-electromechanical systems, considering their technological uncertainties. Nowadays, micro-devices are commonly applied systems, especially in the automotive industry, taking advantage of utilizing both the mechanical structure and electronic control circuit on one board. Their frequent use motivates the elaboration of virtual prototyping tools that can be applied in design optimization with the introduction of technological uncertainties and reliability. The authors present a procedure for the optimization of micro-devices, which is based on the theory of reliability-based robust design optimization. This takes into consideration the performance of a micro-device and its reliability assessed by means of uncertainty analysis. The procedure assumes that, for each checked design configuration, the assessment of uncertainty propagation is performed with the meta-modeling technique. The described procedure is illustrated with an example of the optimization carried out for a finite element model of a micro-mirror. The multi-physics approach allowed the introduction of several physical phenomena to correctly model the electrostatic actuation and the squeezing effect present between electrodes. The optimization was preceded by sensitivity analysis to establish the design and uncertain domains. The genetic algorithms fulfilled the defined optimization task effectively. The best discovered individuals are characterized by a minimized value of the multi-criteria objective function, simultaneously satisfying the constraint on material strength. The restriction of the maximum equivalent stresses was introduced with the conditionally formulated objective function with a penalty component. The yielded results were successfully verified with a global uniform search through the input design domain.
Reliability-based robust design optimization of vehicle components, Part II: Case studies
NASA Astrophysics Data System (ADS)
Zhang, Yimin
2015-06-01
The reliability-based optimization, the reliability- based sensitivity analysis and robust design method are employed to propose an effective approach for reliability-based robust design optimization of vehicle components in Part I. Applications of the method are further discussed for reliability-based robust optimization of vehicle components in this paper. Examples of axles, torsion bar, coil and composite springs are illustrated for numerical investigations. Results have shown the proposed method is an efficient method for reliability-based robust design optimization of vehicle components.
A robust rotorcraft flight control system design methodology utilizing quantitative feedback theory
NASA Technical Reports Server (NTRS)
Gorder, Peter James
1993-01-01
Rotorcraft flight control systems present design challenges which often exceed those associated with fixed-wing aircraft. First, large variations in the response characteristics of the rotorcraft result from the wide range of airspeeds of typical operation (hover to over 100 kts). Second, the assumption of vehicle rigidity often employed in the design of fixed-wing flight control systems is rarely justified in rotorcraft where rotor degrees of freedom can have a significant impact on the system performance and stability. This research was intended to develop a methodology for the design of robust rotorcraft flight control systems. Quantitative Feedback Theory (QFT) was chosen as the basis for the investigation. Quantitative Feedback Theory is a technique which accounts for variability in the dynamic response of the controlled element in the design robust control systems. It was developed to address a Multiple-Input Single-Output (MISO) design problem, and utilizes two degrees of freedom to satisfy the design criteria. Two techniques were examined for extending the QFT MISO technique to the design of a Multiple-Input-Multiple-Output (MIMO) flight control system (FCS) for a UH-60 Black Hawk Helicopter. In the first, a set of MISO systems, mathematically equivalent to the MIMO system, was determined. QFT was applied to each member of the set simultaneously. In the second, the same set of equivalent MISO systems were analyzed sequentially, with closed loop response information from each loop utilized in subsequent MISO designs. The results of each technique were compared, and the advantages of the second, termed Sequential Loop Closure, were clearly evident.
Decentralized adaptive control of robot manipulators with robust stabilization design
NASA Technical Reports Server (NTRS)
Yuan, Bau-San; Book, Wayne J.
1988-01-01
Due to geometric nonlinearities and complex dynamics, a decentralized technique for adaptive control for multilink robot arms is attractive. Lyapunov-function theory for stability analysis provides an approach to robust stabilization. Each joint of the arm is treated as a component subsystem. The adaptive controller is made locally stable with servo signals including proportional and integral gains. This results in the bound on the dynamical interactions with other subsystems. A nonlinear controller which stabilizes the system with uniform boundedness is used to improve the robustness properties of the overall system. As a result, the robot tracks the reference trajectories with convergence. This strategy makes computation simple and therefore facilitates real-time implementation.
Robust control design techniques for active flutter suppression
NASA Technical Reports Server (NTRS)
Ozbay, Hitay; Bachmann, Glen R.
1994-01-01
In this paper, an active flutter suppression problem is studied for a thin airfoil in unsteady aerodynamics. The mathematical model of this system is infinite dimensional because of Theodorsen's function which is irrational. Several second order approximations of Theodorsen's function are compared. A finite dimensional model is obtained from such an approximation. We use H infinity control techniques to find a robustly stabilizing controller for active flutter suppression.
Integration of system identification and robust controller designs for flexible structures in space
NASA Technical Reports Server (NTRS)
Juang, Jer-Nan; Lew, Jiann-Shiun
1990-01-01
A novel approach is developed using experimental data from the structural testing of a physical system to identify a reduced-order model and its error for a robust controller design. There are three steps involved in the approach. First, an approximately balanced model is identified using the eigensystem realization algorithm, which is an identification algorithm. Second, the model error is calculated and described in frequency domain in terms of the H(infinity) norm. Third, a pole-placement technique in combination with an H(infinity) control method is applied to design a controller for the system. A set of experimental data from an existing setup, namely the Mini-Mast system, is used to illustrate and verify the approach development in this paper.
Optimal and Robust Design Method for Two-Chip Out-of-Plane Microaccelerometers
Lee, Sangmin; Ko, Hyoungho; Choi, Byoungdoo; Cho, Dong-il Dan
2010-01-01
In this paper, an optimal and robust design method to implement a two-chip out-of-plane microaccelerometer system is presented. The two-chip microsystem consists of a MEMS chip for sensing the external acceleration and a CMOS chip for signal processing. An optimized design method to determine the device thickness, the sacrificial gap, and the vertical gap length of the M EMS sensing element is applied to minimize the fundamental noise level and also to achieve the robustness to the fabrication variations. In order to cancel out the offset and gain variations due to parasitic capacitances and process variations, a digitally trimmable architecture consisting of an 11 bit capacitor array is adopted in the analog front-end of the CMOS capacitive readout circuit. The out-of-plane microaccelerometer has the scale factor of 372 mV/g∼389 mV/g, the output nonlinearity of 0.43% FSO∼0.60% FSO, the input range of ±2 g and a bias instability of 122 μg∼229 μg. The signal-to-noise ratio and the noise equivalent resolution are measured to be 74.00 dB∼75.23 dB and 180 μg/rtHz∼190 μg/rtHz, respectively. The in-plane cross-axis sensitivities are measured to be 1.1%∼1.9% and 0.3%∼0.7% of the out-of-plane sensitivity, respectively. The results show that the optimal and robust design method for the MEMS sensing element and the highly trimmable capacity of the CMOS capacitive readout circuit are suitable to enhance the die-to-die uniformity of the packaged microsystem, without compromising the performance characteristics. PMID:22163484
NASA Technical Reports Server (NTRS)
Collins, Emmanuel G., Jr.; Richter, Stephen
1990-01-01
One well known deficiency of LQG compensators is that they do not guarantee any measure of robustness. This deficiency is especially highlighted when considering control design for complex systems such as flexible structures. There has thus been a need to generalize LQG theory to incorporate robustness constraints. Here we describe the maximum entropy approach to robust control design for flexible structures, a generalization of LQG theory, pioneered by Hyland, which has proved useful in practice. The design equations consist of a set of coupled Riccati and Lyapunov equations. A homotopy algorithm that is used to solve these design equations is presented.
NASA Technical Reports Server (NTRS)
Yedavalli, R. K.
1992-01-01
The aspect of controller design for improving the ride quality of aircraft in terms of damping ratio and natural frequency specifications on the short period dynamics is addressed. The controller is designed to be robust with respect to uncertainties in the real parameters of the control design model such as uncertainties in the dimensional stability derivatives, imperfections in actuator/sensor locations and possibly variations in flight conditions, etc. The design is based on a new robust root clustering theory developed by the author by extending the nominal root clustering theory of Gutman and Jury to perturbed matrices. The proposed methodology allows to get an explicit relationship between the parameters of the root clustering region and the uncertainty radius of the parameter space. The current literature available for robust stability becomes a special case of this unified theory. The bounds derived on the parameter perturbation for robust root clustering are then used in selecting the robust controller.
NASA Astrophysics Data System (ADS)
Shin, Sangmun; Cho, Byung Rae
2008-11-01
Many practitioners and researchers have implemented robust design and tolerance design as quality improvement and process optimization tools for more than two decades. Robust design is an enhanced process/product design methodology for determining the best settings of control factors while minimizing process bias and variability. Tolerance design is aimed at determining the best tolerance limits for minimizing the total cost incurred by both the customer and manufacturer by balancing quality loss due to variations in product performance and the cost of controlling these variations. Although robust design and tolerance design have received much attention from researchers and practitioners, there is ample room for improvement. First, most researchers consider robust design and tolerance design as separate research fields. Second, most research work is based on a single quality characteristic. The primary goal of this paper is to integrate a sequential robust design-tolerance design optimization procedure within a bi-objective paradigm, which, the authors believe, is the first attempt in the robust design and tolerance design literature. Models are proposed and numerical examples along with sensitivity analysis are performed for verification purposes.
Design and Validation of Optimized Feedforward with Robust Feedback Control of a Nuclear Reactor
Shaffer, Roman; He Weidong; Edwards, Robert M.
2004-08-15
Design applications for robust feedback and optimized feedforward control, with confirming results from experiments conducted on the Pennsylvania State University TRIGA reactor, are presented. The combination of feedforward and feedback control techniques complement each other in that robust control offers guaranteed closed-loop stability in the presence of uncertainties, and optimized feedforward offers an approach to achieving performance that is sometimes limited by overly conservative robust feedback control. The design approach taken in this work combines these techniques by first designing robust feedback control. Alternative methods for specifying a low-order linear model and uncertainty specifications, while seeking as much performance as possible, are discussed and evaluated. To achieve desired performance characteristics, the optimized feedforward control is then computed by using the nominal nonlinear plant model that incorporates the robust feedback control.
NASA Technical Reports Server (NTRS)
Newsom, J. R.; Mukhopadhyay, V.
1983-01-01
A method for designing robust feedback controllers for multiloop systems is presented. Robustness is characterized in terms of the minimum singular value of the system return difference matrix at the plant input. Analytical gradients of the singular values with respect to design variables in the controller are derived. A cumulative measure of the singular values and their gradients with respect to the design variables is used with a numerical optimization technique to increase the system's robustness. Both unconstrained and constrained optimization techniques are evaluated. Numerical results are presented for a two output drone flight control system.
Robustness of fuzzy logic power system stabilizers applied to multimachine power system
Hiyama, Takashi . Dept. of Electrical Engineering and Computer Science)
1994-09-01
This paper investigates the robustness of fuzzy logic stabilizers using the information of speed and acceleration states of a study unit. The input signals are the real power output and/or the speed of the study unit. Non-linear simulations show the robustness of the fuzzy logic power system stabilizers. Experiments are also performed by using a micro-machine system. The results show the feasibility of proposed fuzzy logic stabilizer.
Robustness of controllers designed using Galerkin type approximations
NASA Technical Reports Server (NTRS)
Morris, K. A.
1990-01-01
One of the difficulties in designing controllers for infinite-dimensional systems arises from attempting to calculate a state for the system. It is shown that Galerkin type approximations can be used to design controllers which will perform as designed when implemented on the original infinite-dimensional system. No assumptions, other than those typically employed in numerical analysis, are made on the approximating scheme.
Applying Knowledge of Quantitative Design and Analysis
ERIC Educational Resources Information Center
Baskas, Richard S.
2011-01-01
This study compared and contrasted two quantitative scholarly articles in relation to their research designs. Their designs were analyzed by the comparison of research references and research specific vocabulary to describe how various research methods were used. When researching and analyzing quantitative scholarly articles, it is imperative to…
A Robust Design Methodology for Optimal Microscale Secondary Flow Control in Compact Inlet Diffusers
NASA Technical Reports Server (NTRS)
Anderson, Bernhard H.; Keller, Dennis J.
2001-01-01
It is the purpose of this study to develop an economical Robust design methodology for microscale secondary flow control in compact inlet diffusers. To illustrate the potential of economical Robust Design methodology, two different mission strategies were considered for the subject inlet, namely Maximum Performance and Maximum HCF Life Expectancy. The Maximum Performance mission maximized total pressure recovery while the Maximum HCF Life Expectancy mission minimized the mean of the first five Fourier harmonic amplitudes, i.e., 'collectively' reduced all the harmonic 1/2 amplitudes of engine face distortion. Each of the mission strategies was subject to a low engine face distortion constraint, i.e., DC60<0.10, which is a level acceptable for commercial engines. For each of these missions strategies, an 'Optimal Robust' (open loop control) and an 'Optimal Adaptive' (closed loop control) installation was designed over a twenty degree angle-of-incidence range. The Optimal Robust installation used economical Robust Design methodology to arrive at a single design which operated over the entire angle-of-incident range (open loop control). The Optimal Adaptive installation optimized all the design parameters at each angle-of-incidence. Thus, the Optimal Adaptive installation would require a closed loop control system to sense a proper signal for each effector and modify that effector device, whether mechanical or fluidic, for optimal inlet performance. In general, the performance differences between the Optimal Adaptive and Optimal Robust installation designs were found to be marginal. This suggests, however, that Optimal Robust open loop installation designs can be very competitive with Optimal Adaptive close loop designs. Secondary flow control in inlets is inherently robust, provided it is optimally designed. Therefore, the new methodology presented in this paper, combined array 'Lower Order' approach to Robust DOE, offers the aerodynamicist a very viable and
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.
Robust Kalman filter design for active flutter suppression systems
NASA Technical Reports Server (NTRS)
Garrard, W. L.; Mahesh, J. K.; Stone, C. R.; Dunn, H. J.
1982-01-01
Additional insight is provided into the use of the Doyle-Stein (1979, 1981) technique in aeroelastic control problems by examining the application of the method to a flutter control problem. The system to be controlled consists of a full-size wind tunnel model of a wing, plus an aileron, an actuator, and an accelerometer used to sense the motion of the wing. A full-state feedback controller was designed using linear optimal control theory, and a Kalman filter was used in the feedback loop for state estimation. The filter design procedure is explained along with that to improve closed-loop properties of the system. The locus of the poles of the filter is examined as a scalar design parameter is varied. The Doyle-Stein design procedure is shown to substantially improve the stability properties of an active flutter controller designed using the linear quadratic Gaussian control theory.
Two Reconfigurable Flight-Control Design Methods: Robust Servomechanism and Control Allocation
NASA Technical Reports Server (NTRS)
Burken, John J.; Lu, Ping; Wu, Zheng-Lu; Bahm, Cathy
2001-01-01
Two methods for control system reconfiguration have been investigated. The first method is a robust servomechanism control approach (optimal tracking problem) that is a generalization of the classical proportional-plus-integral control to multiple input-multiple output systems. The second method is a control-allocation approach based on a quadratic programming formulation. A globally convergent fixed-point iteration algorithm has been developed to make onboard implementation of this method feasible. These methods have been applied to reconfigurable entry flight control design for the X-33 vehicle. Examples presented demonstrate simultaneous tracking of angle-of-attack and roll angle commands during failures of the fight body flap actuator. Although simulations demonstrate success of the first method in most cases, the control-allocation method appears to provide uniformly better performance in all cases.
Using open robust design models to estimate temporary emigration from capture-recapture data
Kendall, W.L.; Bjorkland, R.
2001-01-01
Capture-recapture studies are crucial in many circumstances for estimating demographic parameters for wildlife and fish populations. Pollock's robust design, involving multiple sampling occasions per period of interest, provides several advantages over classical approaches. This includes the ability to estimate the probability of being present and available for detection, which in some situations is equivalent to breeding probability. We present a model for estimating availability for detection that relaxes two assumptions required in previous approaches. The first is that the sampled population is closed to additions and deletions across samples within a period of interest. The second is that each member of the population has the same probability of being available for detection in a given period. We apply our model to estimate survival and breeding probability in a study of hawksbill sea turtles (Eretmochelys imbricata), where previous approaches are not appropriate.
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.
Jumbo squid beaks: inspiration for design of robust organic composites.
Miserez, Ali; Li, Youli; Waite, J Herbert; Zok, Frank
2007-01-01
The hard tissues found in some invertebrate marine organisms represent intriguing paradigms for robust, lightweight materials. The present study focuses on one such tissue: that comprising the beak of the jumbo squid (Dosidicus gigas). Its main constituents are chitin fibers (15-20wt.%) and histidine- and glycine-rich proteins (40-45%). Notably absent are mineral phases, metals and halogens. Despite being fully organic, beak hardness and stiffness are at least twice those of the most competitive synthetic organic materials (notably engineering polymers) and comparable to those of Glycera and Nereis jaws. Furthermore, the combination of hardness and stiffness makes the beaks more resistant to plastic deformation when in contact with blunt abrasives than virtually all metals and polymers. The 3,4-dihydroxy-l-phenylalanine and abundant histidine content in the beak proteins as well as the pigmented hydrolysis-resistant residue are suggestive of aromatic cross-linking. A high cross-linking density between the proteins and chitin may be the single most important determinant of hardness and stiffness in the beak. Beak microstructure is characterized by a lamellar arrangement of the constituents, with a weak interface that promotes crack deflection and endows the structure with high fracture toughness. The susceptibility of this microstructure to cracking along these interfaces from contact stresses at the external surface is mitigated by the presence of a protective coating. PMID:17113369
Systems design analysis applied to launch vehicle configuration
NASA Technical Reports Server (NTRS)
Ryan, R.; Verderaime, V.
1993-01-01
As emphasis shifts from optimum-performance aerospace systems to least lift-cycle costs, systems designs must seek, adapt, and innovate cost improvement techniques in design through operations. The systems design process of concept, definition, and design was assessed for the types and flow of total quality management techniques that may be applicable in a launch vehicle systems design analysis. Techniques discussed are task ordering, quality leverage, concurrent engineering, Pareto's principle, robustness, quality function deployment, criteria, and others. These cost oriented techniques are as applicable to aerospace systems design analysis as to any large commercial system.
NASA Technical Reports Server (NTRS)
Burken, John J.
2005-01-01
This viewgraph presentation reviews the use of a Robust Servo Linear Quadratic Regulator (LQR) and a Radial Basis Function (RBF) Neural Network in reconfigurable flight control designs in adaptation to a aircraft part failure. The method uses a robust LQR servomechanism design with model Reference adaptive control, and RBF neural networks. During the failure the LQR servomechanism behaved well, and using the neural networks improved the tracking.
NASA Technical Reports Server (NTRS)
Belcastro, Christine M.; Chang, B.-C.; Fischl, Robert
1989-01-01
In the design and analysis of robust control systems for uncertain plants, the technique of formulating what is termed an M-delta model has become widely accepted and applied in the robust control literature. The M represents the transfer function matrix M(s) of the nominal system, and delta represents an uncertainty matrix acting on M(s). The uncertainty can arise from various sources, such as structured uncertainty from parameter variations or multiple unstructured uncertainties from unmodeled dynamics and other neglected phenomena. In general, delta is a block diagonal matrix, and for real parameter variations the diagonal elements are real. As stated in the literature, this structure can always be formed for any linear interconnection of inputs, outputs, transfer functions, parameter variations, and perturbations. However, very little of the literature addresses methods for obtaining this structure, and none of this literature addresses a general methodology for obtaining a minimal M-delta model for a wide class of uncertainty. Since have a delta matrix of minimum order would improve the efficiency of structured singular value (or multivariable stability margin) computations, a method of obtaining a minimal M-delta model would be useful. A generalized method of obtaining a minimal M-delta structure for systems with real parameter variations is given.
Optimisation in the Design of Environmental Sensor Networks with Robustness Consideration
Budi, Setia; de Souza, Paulo; Timms, Greg; Malhotra, Vishv; Turner, Paul
2015-01-01
This work proposes the design of Environmental Sensor Networks (ESN) through balancing robustness and redundancy. An Evolutionary Algorithm (EA) is employed to find the optimal placement of sensor nodes in the Region of Interest (RoI). Data quality issues are introduced to simulate their impact on the performance of the ESN. Spatial Regression Test (SRT) is also utilised to promote robustness in data quality of the designed ESN. The proposed method provides high network representativeness (fit for purpose) with minimum sensor redundancy (cost), and ensures robustness by enabling the network to continue to achieve its objectives when some sensors fail. PMID:26633392
Robust Coordinated AVR-PSS Design Using H∞ Static Output Feedback Control
NASA Astrophysics Data System (ADS)
Bevrani, Hassan; Hiyama, Takashi
This paper addresses a new robust control methodology to enhance the power system stability and voltage regulation as an integrated design approach. The automatic voltage regulation (AVR) and power system stabilizer (PSS) design problems are reduced to solve a single H∞ based static output feedback control problem. To determine the optimal gains, an iterative linear matrix inequalities (LMI) algorithm is used. A four-machine infinite-bus system example is given to demonstrate the efficiency of developed approach. The proposed robust technique is shown to maintain the robust performance and minimize the effects of disturbances, properly.
Robust Multivariable Optimization and Performance Simulation for ASIC Design
NASA Technical Reports Server (NTRS)
DuMonthier, Jeffrey; Suarez, George
2013-01-01
Application-specific-integrated-circuit (ASIC) design for space applications involves multiple challenges of maximizing performance, minimizing power, and ensuring reliable operation in extreme environments. This is a complex multidimensional optimization problem, which must be solved early in the development cycle of a system due to the time required for testing and qualification severely limiting opportunities to modify and iterate. Manual design techniques, which generally involve simulation at one or a small number of corners with a very limited set of simultaneously variable parameters in order to make the problem tractable, are inefficient and not guaranteed to achieve the best possible results within the performance envelope defined by the process and environmental requirements. What is required is a means to automate design parameter variation, allow the designer to specify operational constraints and performance goals, and to analyze the results in a way that facilitates identifying the tradeoffs defining the performance envelope over the full set of process and environmental corner cases. The system developed by the Mixed Signal ASIC Group (MSAG) at the Goddard Space Flight Center is implemented as a framework of software modules, templates, and function libraries. It integrates CAD tools and a mathematical computing environment, and can be customized for new circuit designs with only a modest amount of effort as most common tasks are already encapsulated. Customization is required for simulation test benches to determine performance metrics and for cost function computation.
Applying colour science in colour design
NASA Astrophysics Data System (ADS)
Luo, Ming Ronnier
2006-06-01
Although colour science has been widely used in a variety of industries over the years, it has not been fully explored in the field of product design. This paper will initially introduce the three main application fields of colour science: colour specification, colour-difference evaluation and colour appearance modelling. By integrating these advanced colour technologies together with modern colour imaging devices such as display, camera, scanner and printer, some computer systems have been recently developed to assist designers for designing colour palettes through colour selection by means of a number of widely used colour order systems, for creating harmonised colour schemes via a categorical colour system, for generating emotion colours using various colour emotional scales and for facilitating colour naming via a colour-name library. All systems are also capable of providing accurate colour representation on displays and output to different imaging devices such as printers.
Designing Robust and Reliable Timestamps for Remote Patient Monitoring.
Clarke, Malcolm; Schluter, Paul; Reinhold, Barry; Reinhold, Brian
2015-09-01
Having timestamps that are robust and reliable is essential for remote patient monitoring in order for patient data to have context and to be correlated with other data. However, unlike hospital systems for which guidelines on timestamps are currently provided by HL7 and IHE, remote patient monitoring platforms are: operated in environments where it can be difficult to synchronize with reliable time sources; include devices with simple or no clock; and may store data spanning significant periods before able to upload. Existing guidelines prove inadequate. This paper analyzes the requirements and the operating scenarios of remote patient monitoring platforms and defines a framework to convey information on the conditions under which observations were made by the device and forwarded by the gateway in order for data to be managed appropriately and to include both reference to local time and an underlying continuous reference timeline. We define the timestamp formats of HL7 to denote the different conditions of operation and describe extensions to the existing definition of the HL7 timestamp to differentiate between time local to GMT (+0000) and universal coordinated time or network time protocol time where no geographic time zone is implied (-0000). We further describe how timestamps from devices having only simple or no clocks might be managed reliably by a gateway to provide timestamps that are referenced to local time and an underlying continuous reference timeline. We extend the HL7 message to include information to permit a subsequent receiver of the data to understand the quality of the timestamp and how it has been translated. We present evaluation from deploying a platform for 12 months. PMID:25095271
NASA Astrophysics Data System (ADS)
Gharibnezhad, Fahit; Mujica, Luis E.; Rodellar, José
2015-01-01
Using Principal Component Analysis (PCA) for Structural Health Monitoring (SHM) has received considerable attention over the past few years. PCA has been used not only as a direct method to identify, classify and localize damages but also as a significant primary step for other methods. Despite several positive specifications that PCA conveys, it is very sensitive to outliers. Outliers are anomalous observations that can affect the variance and the covariance as vital parts of PCA method. Therefore, the results based on PCA in the presence of outliers are not fully satisfactory. As a main contribution, this work suggests the use of robust variant of PCA not sensitive to outliers, as an effective way to deal with this problem in SHM field. In addition, the robust PCA is compared with the classical PCA in the sense of detecting probable damages. The comparison between the results shows that robust PCA can distinguish the damages much better than using classical one, and even in many cases allows the detection where classic PCA is not able to discern between damaged and non-damaged structures. Moreover, different types of robust PCA are compared with each other as well as with classical counterpart in the term of damage detection. All the results are obtained through experiments with an aircraft turbine blade using piezoelectric transducers as sensors and actuators and adding simulated damages.
Applied virtual reality in aerospace design
NASA Technical Reports Server (NTRS)
Hale, Joseph P.
1995-01-01
A virtual reality (VR) applications program has been under development at the Marshall Space Flight Center (MSFC) since 1989. The objectives of the MSFC VR Applications Program are to develop, assess, validate, and utilize VR in hardware development, operations development and support, mission operations training and science training. Before VR can be used with confidence in a particular application, VR must be validated for that class of applications. For that reason, specific validation studies for selected classes of applications have been proposed and are currently underway. These include macro-ergonomic 'control room class' design analysis, Spacelab stowage reconfiguration training, a full-body microgravity functional reach simulator, a gross anatomy teaching simulator, and micro-ergonomic design analysis. This paper describes the MSFC VR Applications Program and the validation studies.
NASA Technical Reports Server (NTRS)
Olds, John Robert; Walberg, Gerald D.
1993-01-01
Multidisciplinary design optimization (MDO) is an emerging discipline within aerospace engineering. Its goal is to bring structure and efficiency to the complex design process associated with advanced aerospace launch vehicles. Aerospace vehicles generally require input from a variety of traditional aerospace disciplines - aerodynamics, structures, performance, etc. As such, traditional optimization methods cannot always be applied. Several multidisciplinary techniques and methods were proposed as potentially applicable to this class of design problem. Among the candidate options are calculus-based (or gradient-based) optimization schemes and parametric schemes based on design of experiments theory. A brief overview of several applicable multidisciplinary design optimization methods is included. Methods from the calculus-based class and the parametric class are reviewed, but the research application reported focuses on methods from the parametric class. A vehicle of current interest was chosen as a test application for this research. The rocket-based combined-cycle (RBCC) single-stage-to-orbit (SSTO) launch vehicle combines elements of rocket and airbreathing propulsion in an attempt to produce an attractive option for launching medium sized payloads into low earth orbit. The RBCC SSTO presents a particularly difficult problem for traditional one-variable-at-a-time optimization methods because of the lack of an adequate experience base and the highly coupled nature of the design variables. MDO, however, with it's structured approach to design, is well suited to this problem. The result of the application of Taguchi methods, central composite designs, and response surface methods to the design optimization of the RBCC SSTO are presented. Attention is given to the aspect of Taguchi methods that attempts to locate a 'robust' design - that is, a design that is least sensitive to uncontrollable influences on the design. Near-optimum minimum dry weight solutions are
A robust inverse inviscid method for airfoil design
NASA Astrophysics Data System (ADS)
Chaviaropoulos, P.; Dedoussis, V.; Papailiou, K. D.
An irrotational inviscid compressible inverse design method for two-dimensional airfoil profiles is described. The method is based on the potential streamfunction formulation, where the physical space on which the boundaries of the airfoil are sought, is mapped onto the (phi, psi) space via a body-fitted coordinate transformation. A novel procedure based on differential geometry arguments is employed to derive the governing equations for the inverse problem, by requiring the curvature of the flat 2-D Euclidean space to be zero. An auxiliary coordinate transformation permits the definition of C-type computational grids on the (phi, psi) plane resulting to a more accurate description of the leading edge region. Geometry is determined by integrating Frenet equations along the grid lines. To validate the method inverse calculation results are compared to direct, `reproduction', calculation results. The design procedure of a new airfoil shape is also presented.
Robust Control for Microgravity Vibration Isolation using Fixed Order, Mixed H2/Mu Design
NASA Technical Reports Server (NTRS)
Whorton, Mark
2003-01-01
Many space-science experiments need an active isolation system to provide a sufficiently quiescent microgravity environment. Modern control methods provide the potential for both high-performance and robust stability in the presence of parametric uncertainties that are characteristic of microgravity vibration isolation systems. While H2 and H(infinity) methods are well established, neither provides the levels of attenuation performance and robust stability in a compensator with low order. Mixed H2/H(infinity), controllers provide a means for maximizing robust stability for a given level of mean-square nominal performance while directly optimizing for controller order constraints. This paper demonstrates the benefit of mixed norm design from the perspective of robustness to parametric uncertainties and controller order for microgravity vibration isolation. A nominal performance metric analogous to the mu measure, for robust stability assessment is also introduced in order to define an acceptable trade space from which different control methodologies can be compared.
Robust model matching design methodology for a stochastic synthetic gene network.
Chen, Bor-Sen; Chang, Chia-Hung; Wang, Yu-Chao; Wu, Chih-Hung; Lee, Hsiao-Ching
2011-03-01
Synthetic biology has shown its potential and promising applications in the last decade. However, many synthetic gene networks cannot work properly and maintain their desired behaviors due to intrinsic parameter variations and extrinsic disturbances. In this study, the intrinsic parameter uncertainties and external disturbances are modeled in a non-linear stochastic gene network to mimic the real environment in the host cell. Then a non-linear stochastic robust matching design methodology is introduced to withstand the intrinsic parameter fluctuations and to attenuate the extrinsic disturbances in order to achieve a desired reference matching purpose. To avoid solving the Hamilton-Jacobi inequality (HJI) in the non-linear stochastic robust matching design, global linearization technique is used to simplify the design procedure by solving a set of linear matrix inequalities (LMIs). As a result, the proposed matching design methodology of the robust synthetic gene network can be efficiently designed with the help of LMI toolbox in Matlab. Finally, two in silico design examples of the robust synthetic gene network are given to illustrate the design procedure and to confirm the robust model matching performance to achieve the desired behavior in spite of stochastic parameter fluctuations and environmental disturbances in the host cell. PMID:21215760
Reliability Assessment of a Robust Design Under Uncertainty for a 3-D Flexible Wing
NASA Technical Reports Server (NTRS)
Gumbert, Clyde R.; Hou, Gene J. -W.; Newman, Perry A.
2003-01-01
The paper presents reliability assessment results for the robust designs under uncertainty of a 3-D flexible wing previously reported by the authors. Reliability assessments (additional optimization problems) of the active constraints at the various probabilistic robust design points are obtained and compared with the constraint values or target constraint probabilities specified in the robust design. In addition, reliability-based sensitivity derivatives with respect to design variable mean values are also obtained and shown to agree with finite difference values. These derivatives allow one to perform reliability based design without having to obtain second-order sensitivity derivatives. However, an inner-loop optimization problem must be solved for each active constraint to find the most probable point on that constraint failure surface.
A Statistical Approach Reveals Designs for the Most Robust Stochastic Gene Oscillators
2016-01-01
The engineering of transcriptional networks presents many challenges due to the inherent uncertainty in the system structure, changing cellular context, and stochasticity in the governing dynamics. One approach to address these problems is to design and build systems that can function across a range of conditions; that is they are robust to uncertainty in their constituent components. Here we examine the parametric robustness landscape of transcriptional oscillators, which underlie many important processes such as circadian rhythms and the cell cycle, plus also serve as a model for the engineering of complex and emergent phenomena. The central questions that we address are: Can we build genetic oscillators that are more robust than those already constructed? Can we make genetic oscillators arbitrarily robust? These questions are technically challenging due to the large model and parameter spaces that must be efficiently explored. Here we use a measure of robustness that coincides with the Bayesian model evidence, combined with an efficient Monte Carlo method to traverse model space and concentrate on regions of high robustness, which enables the accurate evaluation of the relative robustness of gene network models governed by stochastic dynamics. We report the most robust two and three gene oscillator systems, plus examine how the number of interactions, the presence of autoregulation, and degradation of mRNA and protein affects the frequency, amplitude, and robustness of transcriptional oscillators. We also find that there is a limit to parametric robustness, beyond which there is nothing to be gained by adding additional feedback. Importantly, we provide predictions on new oscillator systems that can be constructed to verify the theory and advance design and modeling approaches to systems and synthetic biology. PMID:26835539
A Statistical Approach Reveals Designs for the Most Robust Stochastic Gene Oscillators.
Woods, Mae L; Leon, Miriam; Perez-Carrasco, Ruben; Barnes, Chris P
2016-06-17
The engineering of transcriptional networks presents many challenges due to the inherent uncertainty in the system structure, changing cellular context, and stochasticity in the governing dynamics. One approach to address these problems is to design and build systems that can function across a range of conditions; that is they are robust to uncertainty in their constituent components. Here we examine the parametric robustness landscape of transcriptional oscillators, which underlie many important processes such as circadian rhythms and the cell cycle, plus also serve as a model for the engineering of complex and emergent phenomena. The central questions that we address are: Can we build genetic oscillators that are more robust than those already constructed? Can we make genetic oscillators arbitrarily robust? These questions are technically challenging due to the large model and parameter spaces that must be efficiently explored. Here we use a measure of robustness that coincides with the Bayesian model evidence, combined with an efficient Monte Carlo method to traverse model space and concentrate on regions of high robustness, which enables the accurate evaluation of the relative robustness of gene network models governed by stochastic dynamics. We report the most robust two and three gene oscillator systems, plus examine how the number of interactions, the presence of autoregulation, and degradation of mRNA and protein affects the frequency, amplitude, and robustness of transcriptional oscillators. We also find that there is a limit to parametric robustness, beyond which there is nothing to be gained by adding additional feedback. Importantly, we provide predictions on new oscillator systems that can be constructed to verify the theory and advance design and modeling approaches to systems and synthetic biology. PMID:26835539
Applying the miniaturization technologies for biosensor design.
Derkus, Burak
2016-05-15
Microengineering technologies give us some opportunities in developing high-tech sensing systems that operate with low volumes of samples, integrates one or more laboratory functions on a single substrate, and enables automation. These millimetric sized devices can be produced for only a few dollars, which makes them promising candidates for mass-production. Besides electron beam lithography, stencil lithography, nano-imprint lithography or dip pen lithography, basic photolithography is the technique which is extensively used for the design of microengineered sensing systems. This technique has some advantages such as easy-to-manufacture, do not require expensive instrumentation, and allow creation of lower micron-sized patterns. In this review, it has been focused on three different type of microengineered sensing devices which are developed using micro/nano-patterning techniques, microfluidic technology, and microelectromechanics system based technology. PMID:26800206
A robust Feasible Directions algorithm for design synthesis
NASA Technical Reports Server (NTRS)
Vanderplaats, G. N.
1983-01-01
A nonlinear optimization algorithm is developed which combines the best features of the Method of Feasible Directions and the Generalized Reduced Gradient Method. This algorithm utilizes the direction-finding sub-problem from the Method of Feasible Directions to find a search direction which is equivalent to that of the Generalized Reduced Gradient Method, but does not require the addition of a large number of slack variables associated with inequality constraints. This method provides a core-efficient algorithm for the solution of optimization problems with a large number of inequality constraints. Further optimization efficiency is derived by introducing the concept of infrequent gradient calculations. In addition, it is found that the sensitivity of the optimum design to changes in the problem parameters can be obtained using this method without the need for second derivatives or Lagrange multipliers. A numerical example is given in order to demonstrate the efficiency of the algorithm and the sensitivity analysis.
Robust H infinity control design for the space station with structured parameter uncertainty
NASA Technical Reports Server (NTRS)
Byun, Kuk-Whan; Wie, Bong; Geller, David; Sunkel, John
1992-01-01
A robust H-infinity control design methodology and its application to a Space Station attitude and momentum control problem are presented. This new approach incorporates nonlinear multi-parameter variations in the state-space formulation of H-infinity control theory. An application of this robust H-infinity control synthesis technique to the Space Station control problem yields a remarkable result in stability robustness with respect to the moments-of-inertia variation of about 73% in one of the structured uncertainty directions. The performance and stability of this new robust H-infinity controller for the Space Station are compared to those of other controllers designed using a standard linear-quadratic-regulator synthesis technique.
Robust H(infinity) control design for the Space Station with structured parameter uncertainty
NASA Technical Reports Server (NTRS)
Byun, Kuk-Whan; Wie, Bong; Geller, David; Sunkel, John
1990-01-01
A robust H(infinity) control design methodology and its application to a Space Station attitude and momentum control problem are presented. This new approach incorporates nonlinear multiparameter variations in the state-space formulation of H(infinity) control theory. An application of this robust control synthesis technique tothe Space Station control problem yields a remarkable result in stability robustness with respect to the moments-of-inertia variation of about 73 percent in one of the structured uncertainty directions. The performance and stability of this new robust H(infinity) controller for the Space Station are compared to those of other controllers designed using a standard linear-quadratic-regulator synthesis technique.
Robust Design of Reliability Test Plans Using Degradation Measures.
Lane, Jonathan Wesley; Lane, Jonathan Wesley; Crowder, Stephen V.; Crowder, Stephen V.
2014-10-01
With short production development times, there is an increased need to demonstrate product reliability relatively quickly with minimal testing. In such cases there may be few if any observed failures. Thus, it may be difficult to assess reliability using the traditional reliability test plans that measure only time (or cycles) to failure. For many components, degradation measures will contain important information about performance and reliability. These measures can be used to design a minimal test plan, in terms of number of units placed on test and duration of the test, necessary to demonstrate a reliability goal. Generally, the assumption is made that the error associated with a degradation measure follows a known distribution, usually normal, although in practice cases may arise where that assumption is not valid. In this paper, we examine such degradation measures, both simulated and real, and present non-parametric methods to demonstrate reliability and to develop reliability test plans for the future production of components with this form of degradation.
Sahni, Narinder S.; Piepel, Gregory F.; Naes, Tormod
2009-04-01
The quality of an industrial product depends on the raw material proportions and the process variable levels, both of which need to be taken into account in designing a product. This article presents a case study from the food industry in which both kinds of variables were studied by combining a constrained mixture experiment design and a central composite process variable design. Based on the natural structure of the situation, a split-plot experiment was designed and models involving the raw material proportions and process variable levels (separately and combined) were fitted. Combined models were used to study: (i) the robustness of the process to variations in raw material proportions, and (ii) the robustness of the raw material recipes with respect to fluctuations in the process variable levels. Further, the expected variability in the robust settings was studied using the bootstrap.
Stochastic Satbility and Performance Robustness of Linear Multivariable Systems
NASA Technical Reports Server (NTRS)
Ryan, Laurie E.; Stengel, Robert F.
1990-01-01
Stochastic robustness, a simple technique used to estimate the robustness of linear, time invariant systems, is applied to a single-link robot arm control system. Concepts behind stochastic stability robustness are extended to systems with estimators and to stochastic performance robustness. Stochastic performance robustness measures based on classical design specifications are introduced, and the relationship between stochastic robustness measures and control system design parameters are discussed. The application of stochastic performance robustness, and the relationship between performance objectives and design parameters are demonstrated by means of example. The results prove stochastic robustness to be a good overall robustness analysis method that can relate robustness characteristics to control system design parameters.
NASA Astrophysics Data System (ADS)
Beuchat, X.; Schaefli, B.; Soutter, M.; Mermoud, A.
2012-02-01
Rainfall is poorly modeled by general circulation models (GCMs) and requires appropriate downscaling for local-scale hydrological impact studies. Such downscaling methods should be robust and accurate (to handle, e.g., extreme events and uncertainties), but the noncontinuous and highly nonlinear nature of rainfall makes this task particularly challenging. This paper brings together and extends state-of-the-art methods into an integrated and robust probabilistic methodology to downscale local daily rainfall series from an ensemble of climate simulations. The downscaling is based on generalized linear models (GLMs) that relate monthly GCM-scale atmospheric variables to local-scale daily rainfall series. A cross-validation step ensures that the fitted models are correctly conditioned by the climate variables, and a statistical procedure is proposed to test whether the statistical relationships identified for the reference period also hold in a future perturbed climate (i.e., to test the stationarity assumption). Additionally, we propose a strategy to downweigh poorly performing GCM-GLM couples. The methodology is assessed at 27 locations covering Switzerland and is shown to perform well in reproducing historical rainfall statistics including extremes and interannual variability. Furthermore, the projections are consistent with the simulations of physically based dynamical models. Using an original visualization method based on heat maps, we show that although the downscaling models were fitted at each of the 27 sites independently, their projections follow a spatially coherent pattern and that regions exhibiting different climate change impacts can be identified.
NASA Astrophysics Data System (ADS)
Ju, Yaping; Zhang, Chuhua
2016-03-01
Blade fouling has been proved to be a great threat to compressor performance in operating stage. The current researches on fouling-induced performance degradations of centrifugal compressors are based mainly on simplified roughness models without taking into account the realistic factors such as spatial non-uniformity and randomness of the fouling-induced surface roughness. Moreover, little attention has been paid to the robust design optimization of centrifugal compressor impellers with considerations of blade fouling. In this paper, a multi-objective robust design optimization method is developed for centrifugal impellers under surface roughness uncertainties due to blade fouling. A three-dimensional surface roughness map is proposed to describe the nonuniformity and randomness of realistic fouling accumulations on blades. To lower computational cost in robust design optimization, the support vector regression (SVR) metamodel is combined with the Monte Carlo simulation (MCS) method to conduct the uncertainty analysis of fouled impeller performance. The analyzed results show that the critical fouled region associated with impeller performance degradations lies at the leading edge of blade tip. The SVR metamodel has been proved to be an efficient and accurate means in the detection of impeller performance variations caused by roughness uncertainties. After design optimization, the robust optimal design is found to be more efficient and less sensitive to fouling uncertainties while maintaining good impeller performance in the clean condition. This research proposes a systematic design optimization method for centrifugal compressors with considerations of blade fouling, providing a practical guidance to the design of advanced centrifugal compressors.
Control design for robust stability in linear regulators: Application to aerospace flight control
NASA Technical Reports Server (NTRS)
Yedavalli, R. K.
1986-01-01
Time domain stability robustness analysis and design for linear multivariable uncertain systems with bounded uncertainties is the central theme of the research. After reviewing the recently developed upper bounds on the linear elemental (structured), time varying perturbation of an asymptotically stable linear time invariant regulator, it is shown that it is possible to further improve these bounds by employing state transformations. Then introducing a quantitative measure called the stability robustness index, a state feedback conrol design algorithm is presented for a general linear regulator problem and then specialized to the case of modal systems as well as matched systems. The extension of the algorithm to stochastic systems with Kalman filter as the state estimator is presented. Finally an algorithm for robust dynamic compensator design is presented using Parameter Optimization (PO) procedure. Applications in a aircraft control and flexible structure control are presented along with a comparison with other existing methods.
Synthesis of structural/control systems robust with respect to design variable tolerances
NASA Technical Reports Server (NTRS)
Thomas, H. L.; Schmit, L. A.
1991-01-01
A methodology is presented for the synthesis of control augmented structures which can be modeled as an assemblage of beam, truss, and nonstructural mass elements augmented by a robust noncollocated direct output feedback control system. The control system is robust in the sense that it can tolerate manufacturing and realization errors. The robust control system is synthesized using a constraint buffering technique in conjunction with the approximation concepts approach to system synthesis. All of the design constraints on the system, including the dynamic stability, are buffered by a nonlinear quantity that is a function of acceptable tolerances on the design variables and the sensitivity of the constraints to changes in these design variables. Numerical results which illustrate the effectiveness of the method presented are given.
Design Method of ILQ Robust Current Control System for Synchronous Reluctance Electrical Motors
NASA Astrophysics Data System (ADS)
Amano, Yoko; Takami, Hiroshi; Fujii, Takao
In this paper, a robust current control system for a synchronous reluctance electrical motor by an ILQ (Inverse Linear Quadratic) design method is proposed newly. First, for performing simultaneously decouple and large region linearization of an d-q axes system in the synchronous reluctance electrical motor using nonlinear state feedback, it is derived that a linear current-voltage state equation linearized model by the d-q axes decouple of the synchronous reluctance electrical motor. Next, according to the ILQ design method, an optimum solution and an optimal condition that achieve the robust current control system for the synchronous reluctance electrical motor are analytically derived, then the robust current control system can be designed. Finally, in practical experiments, we compare the proposed method with the PI (Proportional Integral) control method, the creativity and the usefulness of the proposed method are confirmed by experimental results.
LMI-Based 2-Degrees-of-Freedom Controller Design for Robust Vibration Suppression Positioning
NASA Astrophysics Data System (ADS)
Kato, Takanori; Maeda, Yoshihiro; Iwasaki, Makoto; Hirai, Hiromu
This paper presents a novel 2-degrees-of-freedom (2-DOF) controller design for the robust vibration suppression positioning of mechatronic systems against the frequency perturbation in mechanical vibration modes. The authors have already proposed an linear matrix inequality (LMI)-based feedforward (FF) compensator design method to provide the robust properties in positioning against the perturbation, while the feedback (FB) controller has been independently designed to ensure the robust stability on the basis of the 2-DOF controller design concept. However, a problem still remains in the conventional design that the FB characteristic causes the deterioration of the FF control performance because the undesired response in the FB system due to the perturbation affects the ideal response by the FF compensation. The proposed controller design in this paper, therefore, includes the FB control system with the perturbation in the FF design model to solve the problem in the conventional design. In addition, the FB controller is optimally designed to improve the positioning performance as a cooperated design between FB and FF controllers. The effectiveness of the proposed approach has been verified by numerical simulations and experiments using a prototype.
NASA Technical Reports Server (NTRS)
Troudet, T.; Garg, S.; Merrill, W.
1992-01-01
The design of a dynamic neurocontroller with good robustness properties is presented for a multivariable aircraft control problem. The internal dynamics of the neurocontroller are synthesized by a state estimator feedback loop. The neurocontrol is generated by a multilayer feedforward neural network which is trained through backpropagation to minimize an objective function that is a weighted sum of tracking errors, and control input commands and rates. The neurocontroller exhibits good robustness through stability margins in phase and vehicle output gains. By maintaining performance and stability in the presence of sensor failures in the error loops, the structure of the neurocontroller is also consistent with the classical approach of flight control design.
Multi-point objective-oriented sequential sampling strategy for constrained robust design
NASA Astrophysics Data System (ADS)
Zhu, Ping; Zhang, Siliang; Chen, Wei
2015-03-01
Metamodelling techniques are widely used to approximate system responses of expensive simulation models. In association with the use of metamodels, objective-oriented sequential sampling methods have been demonstrated to be effective in balancing the need for searching an optimal solution versus reducing the metamodelling uncertainty. However, existing infilling criteria are developed for deterministic problems and restricted to one sampling point in one iteration. To exploit the use of multiple samples and identify the true robust solution in fewer iterations, a multi-point objective-oriented sequential sampling strategy is proposed for constrained robust design problems. In this article, earlier development of objective-oriented sequential sampling strategy for unconstrained robust design is first extended to constrained problems. Next, a double-loop multi-point sequential sampling strategy is developed. The proposed methods are validated using two mathematical examples followed by a highly nonlinear automotive crashworthiness design example. The results show that the proposed method can mitigate the effect of both metamodelling uncertainty and design uncertainty, and identify the robust design solution more efficiently than the single-point sequential sampling approach.
Kendall, W.L.; Hines, J.E.
1999-01-01
Several papers have demonstrated the advantages of collecting capture-recapture data using subsamples (i.e. Pollock's robust design). Compared with a standard design (i.e. one sample per period), this approach (1) permits the estimation of more demographic parameters and (2) in many cases produces more efficient estimators. Program SURVIV is a powerful tool for computing parameter estimates under the robust design. However, multinomial models developed for the robust design require cells for each possible capture history that occurs across the subsamples within a period. This makes the process of entering cell probabilities in SURVIV very tedious and subject to errors. Program RDSURVIV combines SURVIV with a front end that converts capture histories taken under the robust design to the proper input format for estimating parameters under a general model, and builds that model. This model permits Markovian temporary emigration, trap response in capture probabilities and time variation in all parameters. Program RDSURVIV also automatically computes estimates under a series of submodels, but also permits the user to specify other submodels.
Kendall, W.L.; Hines, J.E.
1999-01-01
Several papers have demonstrated the advantages of collecting capture-recapture data using subsamples (i.e., Pollock?s robust design). Compared to a standard design (i.e., one sample per period), this approach (1) permits the estimation of more demographic parameters and (2) in many cases produces more efficient estimators. Program SURVIV is a powerful tool for computing parameter estimates under the robust design. However, multinomial models developed for the robust design require cells for each possible capture history that occurs across the subsamples within a period. This makes the process of entering cell probabilities in SURVIV very tedious and subject to errors. Program RDSURVIV combines SURVIV with a front end that converts capture histories taken under the robust design to the proper input format for estimating parameters under a general model, and builds that model. This model permits Markovian temporary emigration, trap response in capture probabilities, and time variation in all parameters. Program RDSURVIV also automatically computes estimates under a series of submodels, but also permits the user to specify other submodels.
Steps toward an Empirical Evaluation of Robust Regression Applied to Reaction-Time Data.
ERIC Educational Resources Information Center
Sternberg, Saul; And Others
Because analyses of reaction-time data are sensitive to aberrant observations and violations of statistical assumptions, a new approach is suggested. In this empirical approach, one applies the same criteria to the problem of selecting a statistical method as one uses to select among alternative experimental procedures. Six criteria are presented…
Applying Learning Design to Work-Based Learning
ERIC Educational Resources Information Center
Miao, Yongwu; Hoppe, Heinz Ulrich
2011-01-01
Learning design is currently slanted to reflect a course-based approach to learning. This article explores whether the concept of learning design could be applied to support the informal aspects of work-based learning (WBL). It also discusses the characteristics of WBL and presents a WBL-specific learning design that highlights the key features…
Universal Design for Online Courses: Applying Principles to Pedagogy
ERIC Educational Resources Information Center
Rao, Kavita; Edelen-Smith, Patricia; Wailehua, Cat-Uyen
2015-01-01
Universal design (UD) educational frameworks provide useful guidelines for designing accessible learning environments with the intention of supporting students with and without disabilities. This article describes how one university instructor defined and applied the principles of Universal Instructional Design (UID) to pedagogy, while designing…
Quality by Design Approaches to Formulation Robustness-An Antibody Case Study.
Wurth, Christine; Demeule, Barthelemy; Mahler, Hanns-Christian; Adler, Michael
2016-05-01
The International Conference on Harmonization Q8 (R2) includes a requirement that "Critical formulation attributes and process parameters are generally identified through an assessment of the extent to which their variation can impact the quality of the drug product," that is, the need to assess the robustness of a formulation. In this article, a quality-by-design-based definition of a "robust formulation" for a biopharmaceutical product is proposed and illustrated with a case study. A multivariate formulation robustness study was performed for a selected formulation of a monoclonal antibody to demonstrate acceptable quality at the target composition as well as at the edges of the allowable composition ranges and fulfillment of the end-of-shelf-life stability requirements of 36 months at the intended storage temperature (2°C-8°C). Extrapolation of 24 months' formulation robustness data to end of shelf life showed that the MAb formulation was robust within the claimed formulation composition ranges. Based on this case study, we propose that a formulation can be claimed as "robust" if all drug substance and drug product critical quality attributes remain within their respective end-of-shelf-life critical quality attribute-acceptance criteria throughout the entire claimed formulation composition range. PMID:27001536
NASA Technical Reports Server (NTRS)
Singh, M.
1999-01-01
Ceramic matrix composite (CMC) components are being designed, fabricated, and tested for a number of high temperature, high performance applications in aerospace and ground based systems. The critical need for and the role of reliable and robust databases for the design and manufacturing of ceramic matrix composites are presented. A number of issues related to engineering design, manufacturing technologies, joining, and attachment technologies, are also discussed. Examples of various ongoing activities in the area of composite databases. designing to codes and standards, and design for manufacturing are given.
A robust design mark-resight abundance estimator allowing heterogeneity in resighting probabilities
McClintock, B.T.; White, Gary C.; Burnham, K.P.
2006-01-01
This article introduces the beta-binomial estimator (BBE), a closed-population abundance mark-resight model combining the favorable qualities of maximum likelihood theory and the allowance of individual heterogeneity in sighting probability (p). The model may be parameterized for a robust sampling design consisting of multiple primary sampling occasions where closure need not be met between primary occasions. We applied the model to brown bear data from three study areas in Alaska and compared its performance to the joint hypergeometric estimator (JHE) and Bowden's estimator (BOWE). BBE estimates suggest heterogeneity levels were non-negligible and discourage the use of JHE for these data. Compared to JHE and BOWE, confidence intervals were considerably shorter for the AICc model-averaged BBE. To evaluate the properties of BBE relative to JHE and BOWE when sample sizes are small, simulations were performed with data from three primary occasions generated under both individual heterogeneity and temporal variation in p. All models remained consistent regardless of levels of variation in p. In terms of precision, the AICc model-averaged BBE showed advantages over JHE and BOWE when heterogeneity was present and mean sighting probabilities were similar between primary occasions. Based on the conditions examined, BBE is a reliable alternative to JHE or BOWE and provides a framework for further advances in mark-resight abundance estimation. ?? 2006 American Statistical Association and the International Biometric Society.
Enhancing Functional Robustness of Gene Regulatory Networks Based on Fitness Landscape Design
NASA Astrophysics Data System (ADS)
Kim, Kyung
We aim to develop design principles for enhancing functional robustness of engineered cells using gene-network topology. We observed the effect of genetic regulation types (inhibition and activation) on robustness. Inhibition was much more stable than activation in E. coli. In the case of activation, if the upstream activator expression is shutdown by mutation, then its downstream expression is shut down as well. Without activation, the activator shutdown due to mutation will make its downstream expression ``remains`` turned off. Thus, the change in the metabolic load is higher in the activation case. Therefore, the stronger activation, the less robust the circuits are. In the inhibition case, we found that the story becomes opposite. When an inhibitor expression is shut down by mutation, the downstream expression turns on because the inhibitor is not expressed. This compensates changes in the metabolic load that might have been decreased without the inhibition. This result presents potential significant roles of network topology on the robustness of engineered cellular networks. This also emphasizes that the concept of fitness landscape, where the local slope corresponds to the fitness difference between different genotypes, can be useful to design robust gene circuits. We acknowledge the support of the NSF (MCB Award # 1515280).
Applying macro design tools to the design of MEMS accelerometers
Davies, B.R.; Rodgers, M.S.; Montague, S.
1998-02-01
This paper describes the design of two different surface micromachined (MEMS) accelerometers and the use of design and analysis tools intended for macro sized devices. This work leverages a process for integrating both the micromechanical structures and microelectronics circuitry of a MEMS accelerometer on the same chip. In this process, the mechanical components of the sensor are first fabricated at the bottom of a trench etched into the wafer substrate. The trench is then filled with oxide and sealed to protect the mechanical components during subsequent microelectronics processing. The wafer surface is then planarized in preparation for CMOS processing. Next, the CMOS electronics are fabricated and the mechanical structures are released. The mechanical structure of each sensor consists of two polysilicon plate masses suspended by multiple springs (cantilevered beam structures) over corresponding polysilicon plates fixed to the substrate to form two parallel plate capacitors. One polysilicon plate mass is suspended using compliant springs forming a variable capacitor. The other polysilicon plate mass is suspended using very stiff springs acting as a fixed capacitor. Acceleration is measured by comparing the variable capacitance with the fixed capacitance during acceleration.
Estimating survival and breeding probability for pond-breeding amphibians: a modified robust design
Bailey, L.L.; Kendall, W.L.; Church, D.R.; Wilbur, H.M.
2004-01-01
Many studies of pond-breeding amphibians involve sampling individuals during migration to and from breeding habitats. Interpreting population processes and dynamics from these studies is difficult because (1) only a proportion of the population is observable each season, while an unknown proportion remains unobservable (e.g., non-breeding adults) and (2) not all observable animals are captured. Imperfect capture probability can be easily accommodated in capture?recapture models, but temporary transitions between observable and unobservable states, often referred to as temporary emigration, is known to cause problems in both open- and closed-population models. We develop a multistate mark?recapture (MSMR) model, using an open-robust design that permits one entry and one exit from the study area per season. Our method extends previous temporary emigration models (MSMR with an unobservable state) in two ways. First, we relax the assumption of demographic closure (no mortality) between consecutive (secondary) samples, allowing estimation of within-pond survival. Also, we add the flexibility to express survival probability of unobservable individuals (e.g., ?non-breeders?) as a function of the survival probability of observable animals while in the same, terrestrial habitat. This allows for potentially different annual survival probabilities for observable and unobservable animals. We apply our model to a relictual population of eastern tiger salamanders (Ambystoma tigrinum tigrinum). Despite small sample sizes, demographic parameters were estimated with reasonable precision. We tested several a priori biological hypotheses and found evidence for seasonal differences in pond survival. Our methods could be applied to a variety of pond-breeding species and other taxa where individuals are captured entering or exiting a common area (e.g., spawning or roosting area, hibernacula).
HEURISTIC OPTIMIZATION AND ALGORITHM TUNING APPLIED TO SORPTIVE BARRIER DESIGN
While heuristic optimization is applied in environmental applications, ad-hoc algorithm configuration is typical. We use a multi-layer sorptive barrier design problem as a benchmark for an algorithm-tuning procedure, as applied to three heuristics (genetic algorithms, simulated ...
Applying axiomatic design to a medication distribution system
NASA Astrophysics Data System (ADS)
Raguini, Pepito B.
As the need to minimize medication errors drives many medical facilities to come up with robust solutions to the most common error that affects patient's safety, these hospitals would be wise to put a concerted effort into finding methodologies that can facilitate an optimized medical distribution system. If the hospitals' upper management is looking for an optimization method that is an ideal fit, it is just as important that the right tool be selected for the application at hand. In the present work, we propose the application of Axiomatic Design (AD), which is a process that focuses on the generation and selection of functional requirements to meet the customer needs for product and/or process design. The appeal of the axiomatic approach is to provide both a formal design process and a set of technical coefficients for meeting the customer's needs. Thus, AD offers a strategy for the effective integration of people, design methods, design tools and design data. Therefore, we propose the AD methodology to medical applications with the main objective of allowing nurses the opportunity to provide cost effective delivery of medications to inpatients, thereby improving quality patient care. The AD methodology will be implemented through the use of focused stores, where medications can be readily stored and can be conveniently located near patients, as well as a mobile apparatus that can also store medications and is commonly used by hospitals, the medication cart. Moreover, a robust methodology called the focused store methodology will be introduced and developed for both the uncapacitated and capacitated case studies, which will set up an appropriate AD framework and design problem for a medication distribution case study.
NASA Technical Reports Server (NTRS)
Garg, Sanjay
1993-01-01
Results are presented from an application of H-infinity control design methodology to a centralized integrated flight/propulsion control (IFPC) system design for a supersonic STOVL fighter aircraft in transition flight. The emphasis is on formulating the H-infinity optimal control synthesis problem such that the critical requirements for the flight and propulsion systems are adequately reflected within the linear, centralized control problem formulation and the resulting controller provides robustness to modeling uncertainties and model parameter variations with flight condition. Detailed evaluation results are presented for a reduced order controller obtained from the improved H-infinity control design showing that the control design meets the specified nominal performance objective as well as provides stability robustness for variations in plant system dynamics with changes in aircraft trim speed within the transition flight envelope.
Applying a fuzzy-set-based method for robust estimation of coupling loss factors
NASA Astrophysics Data System (ADS)
Nunes, R. F.; Ahmida, K. M.; Arruda, J. R. F.
2007-10-01
Finite element models have been used by many authors to provide accurate estimations of coupling loss factors. Although much progress has been achieved in this area, little attention has been paid to the influence of uncertain parameters in the finite element model used to estimate these factors. It is well known that, in the mid-frequency range, uncertainty is a major issue. In this context, a spectral element method combined with a special implementation of a fuzzy-set-based method, which is called the transformation method, is proposed as an alternative to compute coupling loss factors. The proposed technique is applied to a frame-type junction, which can consist of two beams connected at an arbitrary angle. In this context, two problems are investigated. In the first one, the influence of the confidence intervals of the coupling loss factors on the estimated energy envelopes assuming a unit power input is considered. In the other problem the influence of the envelope of the input power obtained considering the confidence intervals of the coupling loss factors is also taken into account. The estimates of the intervals are obtained by using the spectral element method combined with a fuzzy-set-based method. Results using a Monte Carlo analysis for the estimation of the coupling loss factors under the influence of uncertain parameters are shown for comparison and verification of the fuzzy method.
Dynamic reliability-based robust design optimization with time-variant probabilistic constraints
NASA Astrophysics Data System (ADS)
Wang, Pingfeng; Wang, Zequn; Almaktoom, Abdulaziz T.
2014-06-01
With the increasing complexity of engineering systems, ensuring high system reliability and system performance robustness throughout a product life cycle is of vital importance in practical engineering design. Dynamic reliability analysis, which is generally encountered due to time-variant system random inputs, becomes a primary challenge in reliability-based robust design optimization (RBRDO). This article presents a new approach to efficiently carry out dynamic reliability analysis for RBRDO. The key idea of the proposed approach is to convert time-variant probabilistic constraints to time-invariant ones by efficiently constructing a nested extreme response surface (NERS) and then carry out dynamic reliability analysis using NERS in an iterative RBRDO process. The NERS employs an efficient global optimization technique to identify the extreme time responses that correspond to the worst case scenario of system time-variant limit state functions. With these extreme time samples, a kriging-based time prediction model is built and used to estimate extreme responses for any given arbitrary design in the design space. An adaptive response prediction and model maturation mechanism is developed to guarantee the accuracy and efficiency of the proposed NERS approach. The NERS is integrated with RBRDO with time-variant probabilistic constraints to achieve optimum designs of engineered systems with desired reliability and performance robustness. Two case studies are used to demonstrate the efficacy of the proposed approach.
NASA Astrophysics Data System (ADS)
Sarjaš, Andrej; Chowdhury, Amor; Svečko, Rajko
2016-09-01
This paper presents the synthesis of an optimal robust controller design using the polynomial pole placement technique and multi-criteria optimisation procedure via an evolutionary computation algorithm - differential evolution. The main idea of the design is to provide a reliable fixed-order robust controller structure and an efficient closed-loop performance with a preselected nominally characteristic polynomial. The multi-criteria objective functions have quasi-convex properties that significantly improve convergence and the regularity of the optimal/sub-optimal solution. The fundamental aim of the proposed design is to optimise those quasi-convex functions with fixed closed-loop characteristic polynomials, the properties of which are unrelated and hard to present within formal algebraic frameworks. The objective functions are derived from different closed-loop criteria, such as robustness with metric ?∞, time performance indexes, controller structures, stability properties, etc. Finally, the design results from the example verify the efficiency of the controller design and also indicate broader possibilities for different optimisation criteria and control structures.
Robust controller designs for second-order dynamic systems - A virtual passive approach
NASA Technical Reports Server (NTRS)
Juang, Jer-Nan; Phan, Minh
1991-01-01
A robust controller design is presented for second-order dynamic systems. The controller is model-independent and itself is a virtual second-order dynamic system. Conditions on actuator and sensor placements are identified for controller designs that guarantee overall closed-loop stability. The dynamic controller can be viewed as a virtual passive damping system that serves to stabilize the actual dynamic system. The control gians are interpreted as virtual mass, spring, and dashpot elements that play the same roles as actual physical elements in stability analysis. Position, velocity, and acceleration feedback are considered. Simple examples are provided to illustrate the physical meaning of this controller design.
Robust controller designs for second-order dynamic system: A virtual passive approach
NASA Technical Reports Server (NTRS)
Juang, Jer-Nan; Phan, Minh
1990-01-01
A robust controller design is presented for second-order dynamic systems. The controller is model-independent and itself is a virtual second-order dynamic system. Conditions on actuator and sensor placements are identified for controller designs that guarantee overall closed-loop stability. The dynamic controller can be viewed as a virtual passive damping system that serves to stabilize the actual dynamic system. The control gains are interpreted as virtual mass, spring, and dashpot elements that play the same roles as actual physical elements in stability analysis. Position, velocity, and acceleration feedback are considered. Simple examples are provided to illustrate the physical meaning of this controller design.
Design of a nonlinear robust controller for a complete unmanned aerial vehicle mission
NASA Astrophysics Data System (ADS)
Sadraey, Mohammad Hashem
Unmanned Aerial Vehicle (UAV) flight control systems must be capable of delivering the required performance while handling nonlinearities and uncertainties in the vehicle model, the atmosphere, and ambient wind. These factors necessitate the development of nonlinear flight control system design methods that can handle large nonlinearities and uncertainties. Variable approaches to the linear control of UAVs have been discussed in the recent literature. However, the development of a nonlinear robust autopilot has not been addressed to any significant degree. The development of a nonlinear autopilot based on robust control methods will be discussed in this dissertation. In this design technique, the nonlinear UAV model is not linearized. The control law is designed using the Hinfinity technique. This dissertation presents the results of an exploratory study to examine robust autopilot nonlinear design methods for the UAV and compare this new approach with existing PID, LQR, and linear Hinfinity techniques. Since the method must then be verified, its flight simulation will be done using MATLAB/SIMULINK. Verification, validation and robustness tests are documented at the end of this dissertation. The airplane examined is called the Hawkeye. It was designed and built by KU students in the fall of 2004. It is a small, 14 foot wingspan, remotely controlled airplane made from composite materials with a maximum takeoff weight of 90 lbs. It will be used in the future as a small UAV for research programs at KU. The mission includes take-off, climb, cruise, a one and a half circle accomplished in a level turn, and a return back to its original airfield accomplished by cruising back, descending, and completing an approach and landing. After take-off, the airplane is required to climb to 1,000 ft altitude, and then it travels 5,000 ft over the ground into the target area. It will then take some photos of that target using its camera. The complete mission for the UAV lasts about
Design of inner coupling matrix for robustly self-synchronizing networks
NASA Astrophysics Data System (ADS)
Gequn, Liu; Zhiguo, Zhan; Knowles, Gareth
2015-12-01
A self-synchronizing network may undergo change of scale and topology during its functioning, thus adjustment of parameters is necessary to enable the synchronization. The adjustment cost and runtime-break demand a method to maintain continuous operation of the network. To address these issues, this paper presents an analytical method for the design of the inner coupling matrix. The proposed method renders the synchronization robust to change of network scale and topology. It is usual in network models that scale and topology are represented by outer coupling matrix. In this paper we only consider diffusively coupled networks. For these networks, the eigenvalues of the outer coupling matrix are all non-positive. By utilizing this property, the designed inner coupling matrix can cover the entire left half of complex plane within the synchronized region to underlie robustness of synchronization. After elaborating the applicability of several types of synchronization state for a robustly self-synchronizing network, the analytical design method is given for the stable equilibrium point case. Sometimes the Jacobian matrix of the node dynamical equation may lead to an unrealizable complex inner coupling matrix in the method. We then introduce a lemma of matrix transformation to prevent this possibility. Additionally, we investigated the choice of inner coupling matrix to get a desirable self-synchronization speed. The corresponding condition in the design procedure is given to drive the network synchronization faster than convergence of each node. Finally, the article includes examples that show effectiveness and soundness of the method.
Converse, S.J.; Kendall, W.L.; Doherty, P.F., Jr.; Naughton, M.B.; Hines, J.E.
2009-01-01
For many animal populations, one or more life stages are not accessible to sampling, and therefore an unobservable state is created. For colonially-breeding populations, this unobservable state could represent the subset of adult breeders that have foregone breeding in a given year. This situation applies to many seabird populations, notably albatrosses, where skipped breeders are either absent from the colony, or are present but difficult to capture or correctly assign to breeding state. Kendall et al. have proposed design strategies for investigations of seabird demography where such temporary emigration occurs, suggesting the use of the robust design to permit the estimation of time-dependent parameters and to increase the precision of estimates from multi-state models. A traditional robust design, where animals are subject to capture multiple times in a sampling season, is feasible in many cases. However, due to concerns that multiple captures per season could cause undue disturbance to animals, Kendall et al. developed a less-invasive robust design (LIRD), where initial captures are followed by an assessment of the ratio of marked-to-unmarked birds in the population or sampled plot. This approach has recently been applied in the Northwestern Hawaiian Islands to populations of Laysan (Phoebastria immutabilis) and black-footed (P. nigripes) albatrosses. In this paper, we outline the LIRD and its application to seabird population studies. We then describe an approach to determining optimal allocation of sampling effort in which we consider a non-robust design option (nRD), and variations of both the traditional robust design (RD), and the LIRD. Variations we considered included the number of secondary sampling occasions for the RD and the amount of total effort allocated to the marked-to-unmarked ratio assessment for the LIRD. We used simulations, informed by early data from the Hawaiian study, to address optimal study design for our example cases. We found that
NASA Astrophysics Data System (ADS)
Ho, D.; Salmonson, J.; Haan, S.; Clark, D.; Lindl, J.; Meezan, N.; Thomas, C.
2015-11-01
We present six ignition designs using W-doped HDC ablators with, respectively, 2, 3, and 4-step increases in Tr. Fuel adiabat α ranges between 1.5 and 4. The 4-step design has the lowest α of 1.5 but has the highest ablation front Rayleigh-Taylor (RT) growth. Consequently, the overall robustness of the 4-step design is inferior to the intermediate- α 3-step design, assuming typical currently measured surface roughness spectrum. As the foot level is increased further and the shocks merge inside the fuel, the fuel adiabat is raised to 4. The RT growth and mix are reduced but the 1D margin is decreased making it overall more susceptible to surface roughness. The 2-step α = 2.5 design turns out to be the most robust against surface roughness and still can deliver very high 1D yield of 14.5 MJ. Systematic evaluation of the robustness of these capsules with respect to low-mode radiation asymmetries, will also be discussed. Different paths to achieve low-convergence-ratio implosions (i.e. high velocity and high α as one option versus low velocity and low α as another option), while still giving respectable neutron yield will be presented. Finally, we discuss how the performance of these doped capsules changes; if the Au wall of the hohlraum is replaced by U. Work performed under auspices of U.S. DOE by LLNL under DE-AC52-07NA27344.
Hierarchical Modeling and Robust Synthesis for the Preliminary Design of Large Scale Complex Systems
NASA Technical Reports Server (NTRS)
Koch, Patrick N.
1997-01-01
Large-scale complex systems are characterized by multiple interacting subsystems and the analysis of multiple disciplines. The design and development of such systems inevitably requires the resolution of multiple conflicting objectives. The size of complex systems, however, prohibits the development of comprehensive system models, and thus these systems must be partitioned into their constituent parts. Because simultaneous solution of individual subsystem models is often not manageable iteration is inevitable and often excessive. In this dissertation these issues are addressed through the development of a method for hierarchical robust preliminary design exploration to facilitate concurrent system and subsystem design exploration, for the concurrent generation of robust system and subsystem specifications for the preliminary design of multi-level, multi-objective, large-scale complex systems. This method is developed through the integration and expansion of current design techniques: Hierarchical partitioning and modeling techniques for partitioning large-scale complex systems into more tractable parts, and allowing integration of subproblems for system synthesis; Statistical experimentation and approximation techniques for increasing both the efficiency and the comprehensiveness of preliminary design exploration; and Noise modeling techniques for implementing robust preliminary design when approximate models are employed. Hierarchical partitioning and modeling techniques including intermediate responses, linking variables, and compatibility constraints are incorporated within a hierarchical compromise decision support problem formulation for synthesizing subproblem solutions for a partitioned system. Experimentation and approximation techniques are employed for concurrent investigations and modeling of partitioned subproblems. A modified composite experiment is introduced for fitting better predictive models across the ranges of the factors, and an approach for
NASA Astrophysics Data System (ADS)
Nambu, Yohsuke; Takashima, Toshihide; Inagaki, Akiya
2015-12-01
This paper examines the effects of connecting multiplexing shunt circuits composed of inductors and resistors to piezoelectric transducers so as to improve the robustness of a piezoelectric vibration absorber (PVA). PVAs are well known to be effective at suppressing the vibration of an adaptive structure; their weakness is low robustness to changes in the dynamic parameters of the system, including the main structure and the absorber. In the application to space structures, the temperature-dependency of capacitance of piezoelectric ceramics is the factor that causes performance reduction. To improve robustness to the temperature-dependency of the capacitance, this paper proposes a multiple-PVA system that is composed of distributed piezoelectric transducers and several shunt circuits. The optimization problems that determine both the frequencies and the damping ratios of the PVAs are multi-objective problems, which are solved using a real-coded genetic algorithm in this paper. A clamped aluminum beam with four groups of piezoelectric ceramics attached was considered in simulations and experiments. Numerical simulations revealed that the PVA systems designed using the proposed method had tolerance to changes in the capacitances. Furthermore, experiments using a thermostatic bath were conducted to reveal the effectiveness and robustness of the PVA systems. The maximum peaks of the transfer functions of the beam with the open circuit, the single-PVA system, the double-PVA system, and the quadruple-PVA system at 20 °C were 14.3 dB, -6.91 dB, -7.47 dB, and -8.51 dB, respectively. The experimental results also showed that the multiple-PVA system is more robust than a single PVA in a variable temperature environment from -10 °C to 50 °C. In conclusion, the use of multiple PVAs results in an effective, robust vibration control method for adaptive structures.
Robust attitude control design for spacecraft under assigned velocity and control constraints.
Hu, Qinglei; Li, Bo; Zhang, Youmin
2013-07-01
A novel robust nonlinear control design under the constraints of assigned velocity and actuator torque is investigated for attitude stabilization of a rigid spacecraft. More specifically, a nonlinear feedback control is firstly developed by explicitly taking into account the constraints on individual angular velocity components as well as external disturbances. Considering further the actuator misalignments and magnitude deviation, a modified robust least-squares based control allocator is employed to deal with the problem of distributing the previously designed three-axis moments over the available actuators, in which the focus of this control allocation is to find the optimal control vector of actuators by minimizing the worst-case residual error using programming algorithms. The attitude control performance using the controller structure is evaluated through a numerical example. PMID:23618744
Evaluation of power costs in applying TMR to FPGA designs.
Rollins, Nathaniel; Wirthlin, M. J.; Graham, P. S.
2004-01-01
Triple modular redundancy (TMR) is a technique commonly used to mitigate against design failures caused by single event upsets (SEUs). The SEU immunity that TMR provides comes at the cost of increased design area and decreased speed. Additionally, the cost of increased power due to TMR must be considered. This paper evaluates the power costs of TMR and validates the evaluations with actual measurements. Sensitivity to design placement is another important part of this study. Power consumption costs due to TMR are also evaluated in different FPGA architectures. This study shows that power consumption rises in the range of 3x to 7x when TMR is applied to a design.
Sequential approximate optimization-based robust design of SiC-Si3N4 nanocomposite microstructures
NASA Astrophysics Data System (ADS)
Mejía-Rodríguez, Gilberto; Renaud, John E.; Kim, Han Sung; Tomar, Vikas
2013-03-01
A simulation-based robust design optimization methodology to predict the most suitable microstructures of SiC-Si 3N 4 nanocomposites for desired high-temperature toughness is presented. The focus is on finding robust nanocomposite microstructures with maximum toughness at two temperatures: 1500°C and 1600°C. Within this context a sequential approximate optimization algorithm under uncertainty is applied to six different test problems addressing different aspects of robust microstructure generation. During optimization, statistical uncertainties inherent to the computational microstructural generation are quantified and introduced in the optimization framework. The results show that the SiC volume fraction, the number of Si 3N 4 grains, the grain size distribution of the Si 3N 4 grains, and the grain size of the SiC particles have varied effects on the microstructure toughness at different temperatures. At 1500°C, the preferred microstructure is the one with higher Si 3N 4 volume fraction, whereas at 1600°C, the preferred microstructure is the one with higher SiC volume fraction.
Robust controller design for flexible structures using normalized coprime factor plant descriptions
NASA Technical Reports Server (NTRS)
Armstrong, Ernest S.
1993-01-01
Stabilization is a fundamental requirement in the design of feedback compensators for flexible structures. The search for the largest neighborhood around a given design plant for which a single controller produces closed-loop stability can be formulated as an H(sub infinity) control problem. The use of normalized coprime factor plant descriptions, in which the plant perturbations are defined as additive modifications to the coprime factors, leads to a closed-form expression for the maximum neighborhood boundary allowing optimal and suboptimal H(sub infinity) compensators to be computed directly without the usual gamma iteration. A summary of the theory on robust stabilization using normalized coprime factor plant descriptions is presented, and the application of the theory to the computation of robustly stable compensators for the phase version of the Control-Structures Interaction (CSI) Evolutionary Model is described. Results from the application indicate that the suboptimal version of the theory has the potential of providing the bases for the computation of low-authority compensators that are robustly stable to expected variations in design model parameters and additive unmodeled dynamics.
Robust design of spot welds in automotive structures: A decision-making methodology
NASA Astrophysics Data System (ADS)
Ouisse, M.; Cogan, S.
2010-05-01
Automotive structures include thousands of spot welds whose design must allow the assembled vehicle to satisfy a wide variety of performance constraints including static, dynamic and crash criteria. The objective of a standard optimization strategy is to reduce the number of spot welds as much as possible while satisfying all the design objectives. However, a classical optimization of the spot weld distribution using an exhaustive search approach is simply not feasible due to the very high order of the design space and the subsequently prohibitive calculation costs. Moreover, even if this calculation could be done, the result would not necessarily be very informative with respect to the design robustness to manufacturing uncertainties (location of welds and defective welds) and to the degradation of spot welds due to fatigue effects over the lifetime of the vehicle. In this paper, a decision-making methodology is presented which allows some aspects of the robustness issues to be integrated into the spot weld design process. The starting point is a given distribution of spot welds on the structure, which is based on both engineering know-how and preliminary critical numerical results, in particular criteria such as crash behavior. An over-populated spot weld distribution is then built in order to satisfy the remaining design criteria, such as static torsion angle and modal behavior. Then, an efficient optimization procedure based on energy considerations is used to eliminate redundant spot welds while preserving as far as possible the nominal structural behavior. The resulting sub-optimal solution is then used to provide a decision indicator for defining effective quality control procedures (e.g. visual post-assembly inspection of a small number of critical spot welds) as well as designing redundancy into critical zones. The final part of the paper is related to comparing the robustness of competing designs. Some decision-making indicators are presented to help the
Variable-complexity optimization applied to airfoil design
NASA Astrophysics Data System (ADS)
Thokala, Praveen; Martins, Joaquim R. R. A.
2007-04-01
Variable-complexity methods are applied to aerodynamic shape design problems with the objective of reducing the total computational cost of the optimization process. Two main strategies are employed: the use of different levels of fidelity in the analysis models (variable fidelity) and the use of different sets of design variables (variable parameterization). Variable-fidelity methods with three different types of corrections are implemented and applied to a set of two-dimensional airfoil optimization problems that use computational fluid dynamics for the analysis. Variable parameterization is also used to solve the same problems. Both strategies are shown to reduce the computational cost of the optimization.
A methodology for robust structural design with application to active aeroelastic wings
NASA Astrophysics Data System (ADS)
Zink, Paul Scott
A new design process for Active Aeroelastic Wing (AAW) technology was developed, in which control surface gear ratios and structural design variables were treated together in the same optimization problem, acting towards the same objective of weight minimization. This is in contrast to traditional AAW design processes that treat design of the gear ratios and design of the structure as separate optimization problems, each with their own different objectives and constraints, executed in an iterative fashion. The demonstration of the new AAW design process, implemented in an efficient modal-based structural analysis and optimization code, on a lightweight fighter resulted in a 15% reduction in wing box skin weight over a more traditional AAW design process. In addition, the new process was far more streamlined than the traditional approach in that it was performed in one continuous run and did not require the exchange of data between modules. The new AAW design process was then used in the development of a methodology for the design of AAW structures that are robust to uncertainty in maneuver loads which arise from the use of linear aerodynamics. Maneuver load uncertainty was modeled probabilistically and based on typical differences between rigid loads as predicted by nonlinear and linear aerodynamic theory. These models were used to augment the linear aerodynamic loads that had been used in the AAW design process. Characteristics of the robust design methodology included: use of a criticality criterion based on a strain energy formulation to determine what loads were most critical to the structure, Latin Hypercube Sampling for the propagation of uncertainty to the criterion function, and redesign of the structure, using the new AAW design process, to the most critical loads identified. The demonstration of the methodology resulted in a wing box skin structure that was 11% heavier than an AAW structure designed only with linear aerodynamics. However, it was
Pfister, A.; Goossen, C.; Coogler, K.; Gorgemans, J.
2012-07-01
Both the International Atomic Energy Agency (IAEA) and the U.S. Nuclear Regulatory Commission (NRC) require existing and new nuclear power plants to conduct plant assessments to demonstrate the unit's ability to withstand external hazards. The events that occurred at the Fukushima-Dai-ichi nuclear power station demonstrated the importance of designing a nuclear power plant with the ability to protect the plant against extreme external hazards. The innovative design of the AP1000{sup R} nuclear power plant provides unparalleled protection against catastrophic external events which can lead to extensive infrastructure damage and place the plant in an extended abnormal situation. The AP1000 plant is an 1100-MWe pressurized water reactor with passive safety features and extensive plant simplifications that enhance construction, operation, maintenance and safety. The plant's compact safety related footprint and protection provided by its robust nuclear island structures prevent significant damage to systems, structures, and components required to safely shutdown the plant and maintain core and spent fuel pool cooling and containment integrity following extreme external events. The AP1000 nuclear power plant has been extensively analyzed and reviewed to demonstrate that it's nuclear island design and plant layout provide protection against both design basis and extreme beyond design basis external hazards such as extreme seismic events, external flooding that exceeds the maximum probable flood limit, and malicious aircraft impact. The AP1000 nuclear power plant uses fail safe passive features to mitigate design basis accidents. The passive safety systems are designed to function without safety-grade support systems (such as AC power, component cooling water, service water, compressed air or HVAC). The plant has been designed to protect systems, structures, and components critical to placing the reactor in a safe shutdown condition within the steel containment vessel
Reliability Engineering and Robust Design: New Methods for Thermal/Fluid Engineering
NASA Astrophysics Data System (ADS)
Cullimore, Brent A.; Tsuyuki, Glenn T.
2002-07-01
Recent years have witnessed more improvement to the SINDA/FLUINT thermohydraulic analyzer than at any other time in its long history. These improvements have included not only expansions in analytic power, but also the additions of high-level modules that offer revolutions in thermal/fluid engineering itself. One such high-level module, "Reliability Engineering," is described in this paper. Reliability Engineering means considering tolerances in design parameters, uncertainties in environments, uncertainties in application (e.g. usage scenarios), and variations in manufacturing as the stochastic phenomena that they are. Using this approach, the probability that a design will achieve its required performance (i.e., the reliability) is calculated, providing an assessment of risk or confidence in the design, and quantifying the amount of over- or under-design present. The design to be evaluated for reliability will likely have been produced using traditional methods. Possibly, the design was generated using the Solver optimizer, another high-level module available in SINDA/FLUINT. Using design optimization, the user quantifies the goals that make one design better than another (mass, efficiency, etc.), and specifies the thresholds or requirements which render a given design viable or useless (exceeding a performance limit, etc.). SINDA/FLUINT then automatically searches for an optimal design. Robust Design means factoring reliability into the development of the design itself: designing for a target reliability and thereby avoiding either costly over-design or dangerous under-design in the first place. Such an approach eliminates a deterministic stack-up of tolerances, worst-case scenarios, safety factors, and margins that have been the traditional approaches for treating uncertainties. In any real system or product, heat transfer and fluid flow play a limited role: there are many other aspects to a successful design than the realm of thermal/fluids that is encompassed
Robust control design with real parameter uncertainty using absolute stability theory. Ph.D. Thesis
NASA Technical Reports Server (NTRS)
How, Jonathan P.; Hall, Steven R.
1993-01-01
The purpose of this thesis is to investigate an extension of mu theory for robust control design by considering systems with linear and nonlinear real parameter uncertainties. In the process, explicit connections are made between mixed mu and absolute stability theory. In particular, it is shown that the upper bounds for mixed mu are a generalization of results from absolute stability theory. Both state space and frequency domain criteria are developed for several nonlinearities and stability multipliers using the wealth of literature on absolute stability theory and the concepts of supply rates and storage functions. The state space conditions are expressed in terms of Riccati equations and parameter-dependent Lyapunov functions. For controller synthesis, these stability conditions are used to form an overbound of the H2 performance objective. A geometric interpretation of the equivalent frequency domain criteria in terms of off-axis circles clarifies the important role of the multiplier and shows that both the magnitude and phase of the uncertainty are considered. A numerical algorithm is developed to design robust controllers that minimize the bound on an H2 cost functional and satisfy an analysis test based on the Popov stability multiplier. The controller and multiplier coefficients are optimized simultaneously, which avoids the iteration and curve-fitting procedures required by the D-K procedure of mu synthesis. Several benchmark problems and experiments on the Middeck Active Control Experiment at M.I.T. demonstrate that these controllers achieve good robust performance and guaranteed stability bounds.
Bionic Concept Applied to Flow Slab Design of PEMFC
NASA Astrophysics Data System (ADS)
Wang, C. T.; Chang, C. P.
A character of fuel cell with high potency and low pollution was known well and considered as a new generation of power technology. In this study a novel design of flow slab addressed and originated from bionic concept will be applied to improve the performance of PEMFC. Simulation results executed at Re = 100 show that the bionic flow type will possess a better uniformity of velocity and lower pressure drop. Besides, the integral performance concerned at SDR and PDR will also show the bionic flow type to be an outstanding design. Hence, this novel flow design addressed will be useful to promotion of PEMFC.
Design of Robust PI Controllers and their Application to a Nonlinear Electronic System
NASA Astrophysics Data System (ADS)
Matušů, Radek; Vaneková, Katarína; Prokop, Roman; Bakošová, Monika
2010-01-01
The principal aim of the paper is to present a possible approach to the design of simple Proportional-Integral (PI) robust controllers and subsequently to demonstrate their applicability during control of a laboratory model with uncertain parameters through the Programmable Logic Controller (PLC) SIMATIC S7-300 by Siemens Company. The proposed and utilized synthesis consists of two steps. The former one is determination of controller parameters area, which ensures the robustly stable control loop and is based on computing/plotting the stability boundary locus while the latter one lies in the final choice of the controller itself relying on algebraic techniques. The basic theoretical parts are followed by laboratory experiments in which the 3rd order nonlinear electronic model has been successfully controlled in various working points.
NASA Technical Reports Server (NTRS)
Turso, James A.; Litt, Jonathan S.
2004-01-01
A method for accommodating engine deterioration via a scheduled Linear Parameter Varying Quadratic Lyapunov Function (LPVQLF)-Based controller is presented. The LPVQLF design methodology provides a means for developing unconditionally stable, robust control of Linear Parameter Varying (LPV) systems. The controller is scheduled on the Engine Deterioration Index, a function of estimated parameters that relate to engine health, and is computed using a multilayer feedforward neural network. Acceptable thrust response and tight control of exhaust gas temperature (EGT) is accomplished by adjusting the performance weights on these parameters for different levels of engine degradation. Nonlinear simulations demonstrate that the controller achieves specified performance objectives while being robust to engine deterioration as well as engine-to-engine variations.
Applying riding-posture optimization on bicycle frame design.
Hsiao, Shih-Wen; Chen, Rong-Qi; Leng, Wan-Lee
2015-11-01
Customization design is a trend for developing a bicycle in recent years. Thus, the comfort of riding a bike is an important factor that should be paid much attention to while developing a bicycle. From the viewpoint of ergonomics, the concept of "fitting object to the human body" is designed into the bicycle frame in this study. Firstly, the important feature points of riding posture were automatically detected by the image processing method. In the measurement process, the best riding posture was identified experimentally, thus the positions of feature points and joint angles of human body were obtained. Afterwards, according to the measurement data, three key points: the handlebar, the saddle and the crank center, were identified and applied to the frame design of various bicycle types. Lastly, this study further proposed a frame size table for common bicycle types, which is helpful for the designer to design a bicycle. PMID:26154206
Probabilistic Methods for Uncertainty Propagation Applied to Aircraft Design
NASA Technical Reports Server (NTRS)
Green, Lawrence L.; Lin, Hong-Zong; Khalessi, Mohammad R.
2002-01-01
Three methods of probabilistic uncertainty propagation and quantification (the method of moments, Monte Carlo simulation, and a nongradient simulation search method) are applied to an aircraft analysis and conceptual design program to demonstrate design under uncertainty. The chosen example problems appear to have discontinuous design spaces and thus these examples pose difficulties for many popular methods of uncertainty propagation and quantification. However, specific implementation features of the first and third methods chosen for use in this study enable successful propagation of small uncertainties through the program. Input uncertainties in two configuration design variables are considered. Uncertainties in aircraft weight are computed. The effects of specifying required levels of constraint satisfaction with specified levels of input uncertainty are also demonstrated. The results show, as expected, that the designs under uncertainty are typically heavier and more conservative than those in which no input uncertainties exist.
Robust Optimal Design of Experiments for Model Discrimination Using an Interactive Software Tool
Stegmaier, Johannes; Skanda, Dominik; Lebiedz, Dirk
2013-01-01
Mathematical modeling of biochemical processes significantly contributes to a better understanding of biological functionality and underlying dynamic mechanisms. To support time consuming and costly lab experiments, kinetic reaction equations can be formulated as a set of ordinary differential equations, which in turn allows to simulate and compare hypothetical models in silico. To identify new experimental designs that are able to discriminate between investigated models, the approach used in this work solves a semi-infinite constrained nonlinear optimization problem using derivative based numerical algorithms. The method takes into account parameter variabilities such that new experimental designs are robust against parameter changes while maintaining the optimal potential to discriminate between hypothetical models. In this contribution we present a newly developed software tool that offers a convenient graphical user interface for model discrimination. We demonstrate the beneficial operation of the discrimination approach and the usefulness of the software tool by analyzing a realistic benchmark experiment from literature. New robust optimal designs that allow to discriminate between the investigated model hypotheses of the benchmark experiment are successfully calculated and yield promising results. The involved robustification approach provides maximally discriminating experiments for the worst parameter configurations, which can be used to estimate the meaningfulness of upcoming experiments. A major benefit of the graphical user interface is the ability to interactively investigate the model behavior and the clear arrangement of numerous variables. In addition to a brief theoretical overview of the discrimination method and the functionality of the software tool, the importance of robustness of experimental designs against parameter variability is demonstrated on a biochemical benchmark problem. The software is licensed under the GNU General Public License
Robust optimal design of experiments for model discrimination using an interactive software tool.
Stegmaier, Johannes; Skanda, Dominik; Lebiedz, Dirk
2013-01-01
Mathematical modeling of biochemical processes significantly contributes to a better understanding of biological functionality and underlying dynamic mechanisms. To support time consuming and costly lab experiments, kinetic reaction equations can be formulated as a set of ordinary differential equations, which in turn allows to simulate and compare hypothetical models in silico. To identify new experimental designs that are able to discriminate between investigated models, the approach used in this work solves a semi-infinite constrained nonlinear optimization problem using derivative based numerical algorithms. The method takes into account parameter variabilities such that new experimental designs are robust against parameter changes while maintaining the optimal potential to discriminate between hypothetical models. In this contribution we present a newly developed software tool that offers a convenient graphical user interface for model discrimination. We demonstrate the beneficial operation of the discrimination approach and the usefulness of the software tool by analyzing a realistic benchmark experiment from literature. New robust optimal designs that allow to discriminate between the investigated model hypotheses of the benchmark experiment are successfully calculated and yield promising results. The involved robustification approach provides maximally discriminating experiments for the worst parameter configurations, which can be used to estimate the meaningfulness of upcoming experiments. A major benefit of the graphical user interface is the ability to interactively investigate the model behavior and the clear arrangement of numerous variables. In addition to a brief theoretical overview of the discrimination method and the functionality of the software tool, the importance of robustness of experimental designs against parameter variability is demonstrated on a biochemical benchmark problem. The software is licensed under the GNU General Public License
A robust approach to human-computer interface design using the Taguchi method
Reed, B.M.
1991-01-01
The application of Dr. Genichi Taguchi's approach for design optimization, called Robust Design, to the design of human-computer interface software is investigated. The taguchi method is used to select a near optimum set of interface design alternatives to improve user acceptance of the resulting interface software product with minimum sensitivity to uncontrollable noise caused by human behavioral characteristics. Design alternatives for interaction with personal micro-computers are identified. Several important and representative alternatives are chosen as design parameters for the Taguchi matrix experiment. A noise field with three human behavioral characteristics as noise factors were chosen as a representative noise array. Task accomplishment scenarios were developed for demonstration of the design parameters on an interactive human-computer interface. Experimentation was conducted using selected human subjects to study the effect of the various settings of the design parameters on user acceptance of the interface. Using the results of the matrix experiment, a near optimum set of design parameter values was selected.
Robust optimal design of diffusion-weighted magnetic resonance experiments for skin microcirculation
NASA Astrophysics Data System (ADS)
Choi, J.; Raguin, L. G.
2010-10-01
Skin microcirculation plays an important role in several diseases including chronic venous insufficiency and diabetes. Magnetic resonance (MR) has the potential to provide quantitative information and a better penetration depth compared with other non-invasive methods such as laser Doppler flowmetry or optical coherence tomography. The continuous progress in hardware resulting in higher sensitivity must be coupled with advances in data acquisition schemes. In this article, we first introduce a physical model for quantifying skin microcirculation using diffusion-weighted MR (DWMR) based on an effective dispersion model for skin leading to a q-space model of the DWMR complex signal, and then design the corresponding robust optimal experiments. The resulting robust optimal DWMR protocols improve the worst-case quality of parameter estimates using nonlinear least squares optimization by exploiting available a priori knowledge of model parameters. Hence, our approach optimizes the gradient strengths and directions used in DWMR experiments to robustly minimize the size of the parameter estimation error with respect to model parameter uncertainty. Numerical evaluations are presented to demonstrate the effectiveness of our approach as compared to conventional DWMR protocols.
Designing Agent Utilities for Coordinated, Scalable and Robust Multi-Agent Systems
NASA Technical Reports Server (NTRS)
Tumer, Kagan
2005-01-01
Coordinating the behavior of a large number of agents to achieve a system level goal poses unique design challenges. In particular, problems of scaling (number of agents in the thousands to tens of thousands), observability (agents have limited sensing capabilities), and robustness (the agents are unreliable) make it impossible to simply apply methods developed for small multi-agent systems composed of reliable agents. To address these problems, we present an approach based on deriving agent goals that are aligned with the overall system goal, and can be computed using information readily available to the agents. Then, each agent uses a simple reinforcement learning algorithm to pursue its own goals. Because of the way in which those goals are derived, there is no need to use difficult to scale external mechanisms to force collaboration or coordination among the agents, or to ensure that agents actively attempt to appropriate the tasks of agents that suffered failures. To present these results in a concrete setting, we focus on the problem of finding the sub-set of a set of imperfect devices that results in the best aggregate device. This is a large distributed agent coordination problem where each agent (e.g., device) needs to determine whether to be part of the aggregate device. Our results show that the approach proposed in this work provides improvements of over an order of magnitude over both traditional search methods and traditional multi-agent methods. Furthermore, the results show that even in extreme cases of agent failures (i.e., half the agents failed midway through the simulation) the system's performance degrades gracefully and still outperforms a failure-free and centralized search algorithm. The results also show that the gains increase as the size of the system (e.g., number of agents) increases. This latter result is particularly encouraging and suggests that this method is ideally suited for domains where the number of agents is currently in the
Free-Energy-Based Design Policy for Robust Network Control against Environmental Fluctuation
Iwai, Takuya; Kominami, Daichi; Murata, Masayuki; Yomo, Tetsuya
2015-01-01
Bioinspired network control is a promising approach for realizing robust network controls. It relies on a probabilistic mechanism composed of positive and negative feedback that allows the system to eventually stabilize on the best solution. When the best solution fails due to environmental fluctuation, the system cannot keep its function until the system finds another solution again. To prevent the temporal loss of the function, the system should prepare some solution candidates and stochastically select available one from them. However, most bioinspired network controls are not designed with this issue in mind. In this paper, we propose a thermodynamics-based design policy that allows systems to retain an appropriate degree of randomness depending on the degree of environmental fluctuation, which prepares the system for the occurrence of environmental fluctuation. Furthermore, we verify the design policy by using an attractor selection model-based multipath routing to run simulation experiments. PMID:26167525
A robust variable sampling time BLDC motor control design based upon μ-synthesis.
Hung, Chung-Wen; Yen, Jia-Yush
2013-01-01
The variable sampling rate system is encountered in many applications. When the speed information is derived from the position marks along the trajectory, one would have a speed dependent sampling rate system. The conventional fixed or multisampling rate system theory may not work in these cases because the system dynamics include the uncertainties which resulted from the variable sampling rate. This paper derived a convenient expression for the speed dependent sampling rate system. The varying sampling rate effect is then translated into multiplicative uncertainties to the system. The design then uses the popular μ-synthesis process to achieve a robust performance controller design. The implementation on a BLDC motor demonstrates the effectiveness of the design approach. PMID:24327804
A Robust Variable Sampling Time BLDC Motor Control Design Based upon μ-Synthesis
Yen, Jia-Yush
2013-01-01
The variable sampling rate system is encountered in many applications. When the speed information is derived from the position marks along the trajectory, one would have a speed dependent sampling rate system. The conventional fixed or multisampling rate system theory may not work in these cases because the system dynamics include the uncertainties which resulted from the variable sampling rate. This paper derived a convenient expression for the speed dependent sampling rate system. The varying sampling rate effect is then translated into multiplicative uncertainties to the system. The design then uses the popular μ-synthesis process to achieve a robust performance controller design. The implementation on a BLDC motor demonstrates the effectiveness of the design approach. PMID:24327804
NASA Astrophysics Data System (ADS)
Badri, Pouya; Amini, Amir; Sojoodi, Mahdi
2016-12-01
This paper deals with designing a robust fixed-order non-fragile dynamic output feedback controller for active suspension system of a quarter-car, by means of convex optimization and linear matrix inequalities (LMIs). Our purpose is to design a low-order controller that keeps the desired design specifications besides the simplicity of the implementation. The proposed controller is capable of asymptotically stabilizing the closed-loop system and developing H∞ control, despite model uncertainties and nonlinear dynamics of the quarter-car as well as the norm bounded perturbations of controller parameters. Furthermore, controller parameters are prevented from taking very large and undesirable amounts through appropriate LMI constraints. Finally, a numerical example is presented to show the effectiveness of the proposed method by comparing it with similar works.
Multivariable output feedback robust adaptive tracking control design for a class of delayed systems
NASA Astrophysics Data System (ADS)
Mirkin, Boris; Gutman, Per-Olof
2015-02-01
In this paper, we develop a model reference adaptive control scheme for a class of multi-input multi-output nonlinearly perturbed dynamic systems with unknown time-varying state delays which is also robust with respect to an external disturbance with unknown bounds. The output feedback adaptive control scheme uses feedback actions only, and thus does not require a direct measurement of the command or disturbance signals. A suitable Lyapunov-Krasovskii type functional is introduced to design the adaptation algorithms and to prove stability.
Faircloth, Brant C.; Glenn, Travis C.
2012-01-01
Ligating adapters with unique synthetic oligonucleotide sequences (sequence tags) onto individual DNA samples before massively parallel sequencing is a popular and efficient way to obtain sequence data from many individual samples. Tag sequences should be numerous and sufficiently different to ensure sequencing, replication, and oligonucleotide synthesis errors do not cause tags to be unrecoverable or confused. However, many design approaches only protect against substitution errors during sequencing and extant tag sets contain too few tag sequences. We developed an open-source software package to validate sequence tags for conformance to two distance metrics and design sequence tags robust to indel and substitution errors. We use this software package to evaluate several commercial and non-commercial sequence tag sets, design several large sets (maxcount = 7,198) of edit metric sequence tags having different lengths and degrees of error correction, and integrate a subset of these edit metric tags to polymerase chain reaction (PCR) primers and sequencing adapters. We validate a subset of these edit metric tagged PCR primers and sequencing adapters by sequencing on several platforms and subsequent comparison to commercially available alternatives. We find that several commonly used sets of sequence tags or design methodologies used to produce sequence tags do not meet the minimum expectations of their underlying distance metric, and we find that PCR primers and sequencing adapters incorporating edit metric sequence tags designed by our software package perform as well as their commercial counterparts. We suggest that researchers evaluate sequence tags prior to use or evaluate tags that they have been using. The sequence tag sets we design improve on extant sets because they are large, valid across the set, and robust to the suite of substitution, insertion, and deletion errors affecting massively parallel sequencing workflows on all currently used platforms
A robust helium-cooled shield/blanket design for ITER
NASA Astrophysics Data System (ADS)
Wong, C. P. C.; Bourque, R. F.; Baxi, C. B.; Colleraine, A. P.; Grunloh, H. J.; Letchenberg, T.; Leuer, J. A.; Reis, E. E.; Redler, K.; Will, R.
1993-11-01
General Atomics Fusion and Reactor Groups have completed a helium-cooled, conceptual shield/blanket design for ITER. The configuration selected is a pressurized tubes design embedded in radially oriented plates. This plate can be made from ferritic steel or from V-alloy. Helium leakage to the plasma chamber is eliminated by conservative, redundant design and proper quality control and inspection programs. High helium pressure at 18 MPa is used to reduce pressure drop and enhance heat transfer. This high gas pressure is believed practical when confined in small diameter tubes. Ample industrial experience exists for safe high gas pressure operations. Inboard shield design is highlighted in this study since the allowable void fraction is more limited. Lithium is used as the thermal contacting medium and for tritium breeding; its safety concerns are minimized by a modular, low inventory design that requires no circulation of the liquid metal for the purpose of heat removal. This design is robust, conservative, reliable, and meets all design goals and requirements. It can also be built with present-day technology.
Probabilistic Design and Analysis for Robust Design of Advanced Thermoelectric Conversion Systems
Hendricks, Terry J.; Karri, Naveen K.
2007-04-01
ABSTRACT Research work has investigated the impacts and effects of single- and multi-variable stochasticity on optimum thermoelectric (TE) system design for automotive and industrial energy recovery applications because many critical design and environmental parameters input to the design optimization process can be randomly variable. Analysis tools and techniques have been developed to investigate a variety of stochastic behaviors in critical input parameters, including Gaussian, Log-Normal, Weibull, Gamma, or any type of user-defined probability distribution. Recent accomplishments discussed in this work show that Gaussian input probability distributions can create non-Gaussian outcome distributions for optimum TE areas, required cold-side mass flow rates, and expected power generation; optimum deterministically-derived designs (TE areas and cold-side mass flow rates) should be significantly modified in response to stochastically variable inputs; and outcome parameter standard deviations can be quite significant and magnified relative to input parameter standard deviations. Multiple variable stochastic inputs tend to significantly increase the output design parameter variability (i.e., standard deviations). Coupled, interactive effects/impacts of multiple stochastic input parameters in this research have demonstrated that reductions of optimum TE areas by 9-10% relative to deterministic optimum values was warranted in key stochastic analyses cases studied. Reductions in required cold-side mass flow rates may also be justified. Optimum system power output also was characterized by relatively high standard deviations and variability as a result of stochastic input parameter effects on the TE design optimization process, this would be an important consideration when integrating the overall power system design with power management electronics and energy storage subsystems.
Sontag, Eduardo; Davidsohn, Noah; Subramanian, Sairam; Purnick, Priscilla E. M.; Lauffenburger, Douglas; Weiss, Ron
2012-01-01
Synthetic biology efforts have largely focused on small engineered gene networks, yet understanding how to integrate multiple synthetic modules and interface them with endogenous pathways remains a challenge. Here we present the design, system integration, and analysis of several large scale synthetic gene circuits for artificial tissue homeostasis. Diabetes therapy represents a possible application for engineered homeostasis, where genetically programmed stem cells maintain a steady population of β-cells despite continuous turnover. We develop a new iterative process that incorporates modular design principles with hierarchical performance optimization targeted for environments with uncertainty and incomplete information. We employ theoretical analysis and computational simulations of multicellular reaction/diffusion models to design and understand system behavior, and find that certain features often associated with robustness (e.g., multicellular synchronization and noise attenuation) are actually detrimental for tissue homeostasis. We overcome these problems by engineering a new class of genetic modules for ‘synthetic cellular heterogeneity’ that function to generate beneficial population diversity. We design two such modules (an asynchronous genetic oscillator and a signaling throttle mechanism), demonstrate their capacity for enhancing robust control, and provide guidance for experimental implementation with various computational techniques. We found that designing modules for synthetic heterogeneity can be complex, and in general requires a framework for non-linear and multifactorial analysis. Consequently, we adapt a ‘phenotypic sensitivity analysis’ method to determine how functional module behaviors combine to achieve optimal system performance. We ultimately combine this analysis with Bayesian network inference to extract critical, causal relationships between a module's biochemical rate-constants, its high level functional behavior in isolation
Assessing target design robustness for Shock Ignition using 3D laser raytracing
NASA Astrophysics Data System (ADS)
Schiavi, Angelo; Atzeni, Stefano; Marocchino, Alberto
2014-10-01
Shock ignition (SI) is a laser direct-drive Inertial Confinement Fusion scheme in which fuel compression and hot spot formation are separated. Shock ignition shows potential for high gain at laser energy below 1 MJ (see review Ref.), and could be tested on present large scale facilities. We produced an analytical model for SI which allows rescaling of target and laser drive parameters starting from a given point design. The goal is to redefine a laser-target configuration increasing the robustness while preserving its performance. We developed a metric for ignition margins specific to SI. We report on simulations of rescaled targets using 2D hydrodynamic fluid model with 3D laser raytracing. The robustness with respect to target fabrication parameters and laser facility fluctuations will be assessed for an original reference design as well as for a rescaled target, testing the accuracy of the ignition margin predictor just developed. Work supported by the Italian MIUR Project PRIN2012AY5LEL.
Porel, A; Sanyal, Y; Kundu, A
2014-01-01
The aim of the present study was the development and validation of a simple, precise and specific reversed phase HPLC method for the simultaneous determination of 22 components present in different essential oils namely cinnamon bark oil, caraway oil and cardamom fruit oil. The chromatographic separation of all the components was achieved on Wakosil-II C18 column with mixture of 30 mM ammonium acetate buffer (pH 4.7), methanol and acetonitrile in different ratio as mobile phase in a ternary linear gradient mode. The calibration graphs plotted with five different concentrations of each component were linear with a regression coefficient R(2) >0.999. The limit of detection and limit of quantitation were estimated for all the components. Effect on analytical responses by small and deliberate variation of critical factors was examined by robustness testing with Design of Experiment employing Central Composite Design and established that this method was robust. The method was then validated for linearity, precision, accuracy, specificity and demonstrated to be applicable to the determination of the ingredients in commercial sample of essential oil. PMID:24799735
A robust approach to the design of an electromagnetic shield based on pyrolitic carbon
NASA Astrophysics Data System (ADS)
Lamberti, Patrizia; Kuzhir, Polina; Tucci, Vincenzo
2016-07-01
A robust approach to the design of an electromagnetic shield based on ultra-thin pyrolytic carbon (PyC, 5 ÷ 110 nm) films is proposed. Finite Element Method (FEM) simulations and Monte Carlo based tolerance analysis are used to show that even a deviation of 15 ÷ 20% from the nominal values of the most important design parameters of the PyC film, i.e. its thickness and sheet resistance, does not significantly affect the wanted level of electromagnetic interference shielding efficiency (EMI SE). The ranges of the SE show that EMI shield based on PyC film is characterized by a robust behavior with respect to the variation of such parameters due to the production processes. Therefore, since the PyC can be produced on a scalable basis, is chemically inert, significantly transparent in the visible range and can be deposited onto both metal and dielectric substrates, including flexible polymers, it may be appropriate for the highly demanding technological needs associated to the graphene revolution and can be developed from laboratory to mass production applications.
A TCAD approach to robust ESD design in oxide-confined VCSELs
NASA Astrophysics Data System (ADS)
Meier, Hektor; Santschi, Rafael; Odermatt, Stefan; Witzigmann, Bernd; Eitel, Sven; Nallet, Franck; Letay, Gergö
2007-02-01
Electrostatic Discharge (ESD) events can cause irreversible damage during production, packaging and application of Vertical-Cavity Surface Emitting Lasers (VCSELs). Experimental investigation of those damage patterns inside a real device is a complex and expensive task. Simulation tools can provide insight into the physics during an actual discharge event. This paper aims to analyze ESD events in VCSELs with a microscopic simulation. With the help of a state-of-the art Technology Computer Aided Design (TCAD) virtual ESD tests are performed on oxide-confined VCSELs. The 2-D simulation model takes into account high-field effects and self-heating in a hydrodynamic framework that allows time-dependent spatially resolved monitoring of critical quantities (such as electric field across the oxide, temperature profile, current densities) during the ESD events. Human Body Model (HBM), Machine Model (MM) and Charged Device Model (CDM) show typical local heating and current crowding effects which may lead to irreversible damaging of the device. For slow ESD events the temperature peak is found near the center of the device. Faster pulses show maximum temperature at the interface between oxide and aperture. Physics-based explanations in terms of local electric field, heat generation and heat transport are given. Oxide aperture, thickness and its position relative to the intrinsic region strongly influence self-heating, electric fields, current density profiles and the dielectric breakdown conditions. The impact of those factors on ESD robustness are analyzed and guidelines for robust ESD design in VCSELs are presented.
Porel, A.; Sanyal, Y.; Kundu, A.
2014-01-01
The aim of the present study was the development and validation of a simple, precise and specific reversed phase HPLC method for the simultaneous determination of 22 components present in different essential oils namely cinnamon bark oil, caraway oil and cardamom fruit oil. The chromatographic separation of all the components was achieved on Wakosil–II C18 column with mixture of 30 mM ammonium acetate buffer (pH 4.7), methanol and acetonitrile in different ratio as mobile phase in a ternary linear gradient mode. The calibration graphs plotted with five different concentrations of each component were linear with a regression coefficient R2 >0.999. The limit of detection and limit of quantitation were estimated for all the components. Effect on analytical responses by small and deliberate variation of critical factors was examined by robustness testing with Design of Experiment employing Central Composite Design and established that this method was robust. The method was then validated for linearity, precision, accuracy, specificity and demonstrated to be applicable to the determination of the ingredients in commercial sample of essential oil. PMID:24799735
Flight control design using a blend of modern nonlinear adaptive and robust techniques
NASA Astrophysics Data System (ADS)
Yang, Xiaolong
In this dissertation, the modern control techniques of feedback linearization, mu synthesis, and neural network based adaptation are used to design novel control laws for two specific applications: F/A-18 flight control and reusable launch vehicle (an X-33 derivative) entry guidance. For both applications, the performance of the controllers is assessed. As a part of a NASA Dryden program to develop and flight test experimental controllers for an F/A-18 aircraft, a novel method of combining mu synthesis and feedback linearization is developed to design longitudinal and lateral-directional controllers. First of all, the open-loop and closed-loop dynamics of F/A-18 are investigated. The production F/A-18 controller as well as the control distribution mechanism are studied. The open-loop and closed-loop handling qualities of the F/A-18 are evaluated using low order transfer functions. Based on this information, a blend of robust mu synthesis and feedback linearization is used to design controllers for a low dynamic pressure envelope of flight conditions. For both the longitudinal and the lateral-directional axes, a robust linear controller is designed for a trim point in the center of the envelope. Then by including terms to cancel kinematic nonlinearities and variations in the aerodynamic forces and moments over the flight envelope, a complete nonlinear controller is developed. In addition, to compensate for the model uncertainty, linearization error and variations between operating points, neural network based adaptation is added to the designed longitudinal controller. The nonlinear simulations, robustness and handling qualities analysis indicate that the performance is similar to or better than that for the production F/A-18 controllers. When the dynamic pressure is very low, the performance of both the experimental and the production flight controllers is degraded, but Level I handling qualities are still achieved. A new generation of Reusable Launch Vehicles
Optimal and robust design of brain-state-in-a-box neural associative memories.
Park, Yonmook
2010-03-01
This paper presents a new optimization approach to the design of associative memories via the brain-state-in-a-box (BSB) neural network. The optimization approach proposed in this paper provides the large and uniform domains of attraction of the prototype patterns, the large robustness margin for the weight matrix of the perturbed BSB neural network, the asymptotic stability of the prototype patterns, and the global stability of the BSB neural network. Based on some known qualitative properties of the BSB neural network and theoretical results presented in this paper, a synthesis method of the BSB-based associative memory is established. The synthesis method presented in this paper is given in the form of a linear matrix inequality-based optimization problem, which can be efficiently solved by a readily available software. Design examples are given to demonstrate the applicability of the proposed method and to compare with the existing synthesis methods. PMID:19914797
A new smooth robust control design for uncertain nonlinear systems with non-vanishing disturbances
NASA Astrophysics Data System (ADS)
Xian, Bin; Zhang, Yao
2016-06-01
In this paper, we consider the control problem for a general class of nonlinear system subjected to uncertain dynamics and non-varnishing disturbances. A smooth nonlinear control algorithm is presented to tackle these uncertainties and disturbances. The proposed control design employs the integral of a nonlinear sigmoid function to compensate the uncertain dynamics, and achieve a uniformly semi-global practical asymptotic stable tracking control of the system outputs. A novel Lyapunov-based stability analysis is employed to prove the convergence of the tracking errors and the stability of the closed-loop system. Numerical simulation results on a two-link robot manipulator are presented to illustrate the performance of the proposed control algorithm comparing with the layer-boundary sliding mode controller and the robust of integration of sign of error control design. Furthermore, real-time experiment results for the attitude control of a quadrotor helicopter are also included to confirm the effectiveness of the proposed algorithm.
NASA Astrophysics Data System (ADS)
Mindrup, Frank M.; Friend, Mark A.; Bauer, Kenneth W.
2011-06-01
There are numerous anomaly detection algorithms proposed for hyperspectral imagery. Robust parameter design (RPD) techniques have been applied to some of these algorithms in an attempt to choose robust settings capable of operating consistently across a large variety of image scenes. Typically, training and test sets of hyperspectral images are chosen randomly. Previous research developed a frameworkfor optimizing anomaly detection in HSI by considering specific image characteristics as noise variables within the context of RPD; these characteristics include the Fisher's score, ratio of target pixels and number of clusters. This paper describes a method for selecting hyperspectral image training and test subsets yielding consistent RPD results based on these noise features. These subsets are not necessarily orthogonal, but still provide improvements over random training and test subset assignments by maximizing the volume and average distance between image noise characteristics. Several different mathematical models representing the value of a training and test set based on such measures as the D-optimal score and various distance norms are tested in a simulation experiment.
Min, H. Jason; Beyeler, Walter E.; Glass, Laura M.
2008-01-01
Background The US government proposes pandemic influenza mitigation guidance that includes isolation and antiviral treatment of ill persons, voluntary household member quarantine and antiviral prophylaxis, social distancing of individuals, school closure, reduction of contacts at work, and prioritized vaccination. Is this the best strategy combination? Is choice of this strategy robust to pandemic uncertainties? What are critical enablers of community resilience? Methods and Findings We systematically simulate a broad range of pandemic scenarios and mitigation strategies using a networked, agent-based model of a community of explicit, multiply-overlapping social contact networks. We evaluate illness and societal burden for alterations in social networks, illness parameters, or intervention implementation. For a 1918-like pandemic, the best strategy minimizes illness to <1% of the population and combines network-based (e.g. school closure, social distancing of all with adults' contacts at work reduced), and case-based measures (e.g. antiviral treatment of the ill and prophylaxis of household members). We find choice of this best strategy robust to removal of enhanced transmission by the young, additional complexity in contact networks, and altered influenza natural history including extended viral shedding. Administration of age-group or randomly targeted 50% effective pre-pandemic vaccine with 7% population coverage (current US H5N1 vaccine stockpile) had minimal effect on outcomes. In order, mitigation success depends on rapid strategy implementation, high compliance, regional mitigation, and rigorous rescinding criteria; these are the critical enablers for community resilience. Conclusions Systematic evaluation of feasible, recommended pandemic influenza interventions generally confirms the US community mitigation guidance yields best strategy choices for pandemic planning that are robust to a wide range of uncertainty. The best strategy combines network- and
NASA Technical Reports Server (NTRS)
Crespo, Luis G.; Bushnell, Dennis M. (Technical Monitor)
2002-01-01
This paper presents a study on the optimization of systems with structured uncertainties, whose inputs and outputs can be exhaustively described in the probabilistic sense. By propagating the uncertainty from the input to the output in the space of the probability density functions and the moments, optimization problems that pursue performance, robustness and reliability based designs are studied. Be specifying the desired outputs in terms of desired probability density functions and then in terms of meaningful probabilistic indices, we settle a computationally viable framework for solving practical optimization problems. Applications to static optimization and stability control are used to illustrate the relevance of incorporating uncertainty in the early stages of the design. Several examples that admit a full probabilistic description of the output in terms of the design variables and the uncertain inputs are used to elucidate the main features of the generic problem and its solution. Extensions to problems that do not admit closed form solutions are also evaluated. Concrete evidence of the importance of using a consistent probabilistic formulation of the optimization problem and a meaningful probabilistic description of its solution is provided in the examples. In the stability control problem the analysis shows that standard deterministic approaches lead to designs with high probability of running into instability. The implementation of such designs can indeed have catastrophic consequences.
Design of SPARC V8 superscalar pipeline applied Tomasulo's algorithm
NASA Astrophysics Data System (ADS)
Yang, Xue; Yu, Lixin; Feng, Yunkai
2014-04-01
A superscalar pipeline applied Tomasulo's algorithm is presented in this paper. The design begins with a dual-issue superscalar processor based on LEON2. Tomasulo's algorithm is adopted to implement out-of-order execution. Instructions are separated into three different parts and executed by three different function units so as to reduce area and promote execution speed. Results wrote back into registers are still in program order, for the aim of ensure the function veracity. Mechanisms of the reservation station, common data bus, and reorder buffer are presented in detail. The structure can sends and executes three instructions at most at a time. Branch prediction can also be realized by reorder buffer. Performance of the scalar pipeline applied Tomasulo's algorithm is promoted by 41.31% compared to singleissue pipeline..
Combining band recovery data and Pollock's robust design to model temporary and permanent emigration
Lindberg, M.S.; Kendall, W.L.; Hines, J.E.; Anderson, M.G.
2001-01-01
Capture-recapture models are widely used to estimate demographic parameters of marked populations. Recently, this statistical theory has been extended to modeling dispersal of open populations. Multistate models can be used to estimate movement probabilities among subdivided populations if multiple sites are sampled. Frequently, however, sampling is limited to a single site. Models described by Burnham (1993, in Marked Individuals in the Study of Bird Populations, 199-213), which combined open population capture-recapture and band-recovery models, can be used to estimate permanent emigration when sampling is limited to a single population. Similarly, Kendall, Nichols, and Hines (1997, Ecology 51, 563-578) developed models to estimate temporary emigration under Pollock's (1982, Journal of Wildlife Management 46, 757-760) robust design. We describe a likelihood-based approach to simultaneously estimate temporary and permanent emigration when sampling is limited to a single population. We use a sampling design that combines the robust design and recoveries of individuals obtained immediately following each sampling period. We present a general form for our model where temporary emigration is a first-order Markov process, and we discuss more restrictive models. We illustrate these models with analysis of data on marked Canvasback ducks. Our analysis indicates that probability of permanent emigration for adult female Canvasbacks was 0.193 (SE = 0.082) and that birds that were present at the study area in year i - 1 had a higher probability of presence in year i than birds that were not present in year i - 1.
Flight control system design factors for applying automated testing techniques
NASA Technical Reports Server (NTRS)
Sitz, Joel R.; Vernon, Todd H.
1990-01-01
Automated validation of flight-critical embedded systems is being done at ARC Dryden Flight Research Facility. The automated testing techniques are being used to perform closed-loop validation of man-rated flight control systems. The principal design features and operational experiences of the X-29 forward-swept-wing aircraft and F-18 High Alpha Research Vehicle (HARV) automated test systems are discussed. Operationally applying automated testing techniques has accentuated flight control system features that either help or hinder the application of these techniques. The paper also discusses flight control system features which foster the use of automated testing techniques.
NASA Astrophysics Data System (ADS)
Dores, Delfim Zambujo Das
2005-11-01
Engineering research over the last few years has successfully demonstrated the potential of thrust vector control using counterflow at conditions up to Mach 2. Flow configurations that include the pitch vectoring of rectangular jets and multi-axis vector control in diamond and axisymmetric nozzle geometries have been studied. Although bistable (on-off) fluid-based control has been around for some time, the present counterflow thrust vector control is unique because proportional and continuous jet response can be achieved in the absence of moving parts, while avoiding jet attachment, which renders most fluidic approaches unacceptable for aircraft and missile control applications. However, before this study, research had been limited to open-loop studies of counterflow thrust vectoring. For practical implementation it was vital that the counterflow scheme be used in conjunction with feedback control. Hence, the focus of this research was to develop and experimentally demonstrate a feedback control design methodology for counterflow thrust vectoring. This research focused on 2-D (pitch) thrust vectoring and addresses four key modeling issues. The first issue is to determine the measured variable to be commanded since the thrust vector angle is not measurable in real time. The second related issue is to determine the static mapping from the thrust vector angle to this measured variable. The third issue is to determine the dynamic relationship between the measured variable and the thrust vector angle. The fourth issue is to develop dynamic models with uncertainty characterizations. The final and main goal was the design and implementation of robust controllers that yield closed-loop systems with fast response times, and avoid overshoot in order to aid in the avoidance of attachment. These controllers should be simple and easy to implement in real applications. Hence, PID design has been chosen. Robust control design is accomplished by using ℓ1 control theory in
Design of Robust Adaptive Unbalance Response Controllers for Rotors with Magnetic Bearings
NASA Technical Reports Server (NTRS)
Knospe, Carl R.; Tamer, Samir M.; Fedigan, Stephen J.
1996-01-01
Experimental results have recently demonstrated that an adaptive open loop control strategy can be highly effective in the suppression of unbalance induced vibration on rotors supported in active magnetic bearings. This algorithm, however, relies upon a predetermined gain matrix. Typically, this matrix is determined by an optimal control formulation resulting in the choice of the pseudo-inverse of the nominal influence coefficient matrix as the gain matrix. This solution may result in problems with stability and performance robustness since the estimated influence coefficient matrix is not equal to the actual influence coefficient matrix. Recently, analysis tools have been developed to examine the robustness of this control algorithm with respect to structured uncertainty. Herein, these tools are extended to produce a design procedure for determining the adaptive law's gain matrix. The resulting control algorithm has a guaranteed convergence rate and steady state performance in spite of the uncertainty in the rotor system. Several examples are presented which demonstrate the effectiveness of this approach and its advantages over the standard optimal control formulation.
Robust fault-tolerant tracking control design for spacecraft under control input saturation.
Bustan, Danyal; Pariz, Naser; Sani, Seyyed Kamal Hosseini
2014-07-01
In this paper, a continuous globally stable tracking control algorithm is proposed for a spacecraft in the presence of unknown actuator failure, control input saturation, uncertainty in inertial matrix and external disturbances. The design method is based on variable structure control and has the following properties: (1) fast and accurate response in the presence of bounded disturbances; (2) robust to the partial loss of actuator effectiveness; (3) explicit consideration of control input saturation; and (4) robust to uncertainty in inertial matrix. In contrast to traditional fault-tolerant control methods, the proposed controller does not require knowledge of the actuator faults and is implemented without explicit fault detection and isolation processes. In the proposed controller a single parameter is adjusted dynamically in such a way that it is possible to prove that both attitude and angular velocity errors will tend to zero asymptotically. The stability proof is based on a Lyapunov analysis and the properties of the singularity free quaternion representation of spacecraft dynamics. Results of numerical simulations state that the proposed controller is successful in achieving high attitude performance in the presence of external disturbances, actuator failures, and control input saturation. PMID:24751476
Silva, Marta M.; Rodrigues, Ana F.; Correia, Cláudia; Sousa, Marcos F.Q.; Brito, Catarina; Coroadinha, Ana S.
2015-01-01
Human embryonic stem cells (hESCs) have an enormous potential as a source for cell replacement therapies, tissue engineering, and in vitro toxicology applications. The lack of standardized and robust bioprocesses for hESC expansion has hindered the application of hESCs and their derivatives in clinical settings. We developed a robust and well-characterized bioprocess for hESC expansion under fully defined conditions and explored the potential of transcriptomic and metabolomic tools for a more comprehensive assessment of culture system impact on cell proliferation, metabolism, and phenotype. Two different hESC lines (feeder-dependent and feeder-free lines) were efficiently expanded on xeno-free microcarriers in stirred culture systems. Both hESC lines maintained the expression of stemness markers such as Oct-4, Nanog, SSEA-4, and TRA1-60 and the ability to spontaneously differentiate into the three germ layers. Whole-genome transcriptome profiling revealed a phenotypic convergence between both hESC lines along the expansion process in stirred-tank bioreactor cultures, providing strong evidence of the robustness of the cultivation process to homogenize cellular phenotype. Under low-oxygen tension, results showed metabolic rearrangement with upregulation of the glycolytic machinery favoring an anaerobic glycolysis Warburg-effect-like phenotype, with no evidence of hypoxic stress response, in contrast to two-dimensional culture. Overall, we report a standardized expansion bioprocess that can guarantee maximal product quality. Furthermore, the “omics” tools used provided relevant findings on the physiological and metabolic changes during hESC expansion in environmentally controlled stirred-tank bioreactors, which can contribute to improved scale-up production systems. Significance The clinical application of human pluripotent stem cells (hPSCs) has been hindered by the lack of robust protocols able to sustain production of high cell numbers, as required for
Designing the Electronic Classroom: Applying Learning Theory and Ergonomic Design Principles.
ERIC Educational Resources Information Center
Emmons, Mark; Wilkinson, Frances C.
2001-01-01
Applies learning theory and ergonomic principles to the design of effective learning environments for library instruction. Discusses features of electronic classroom ergonomics, including the ergonomics of physical space, environmental factors, and workstations; and includes classroom layouts. (Author/LRW)
Data-Division-Specific Robustness and Power of Randomization Tests for ABAB Designs
ERIC Educational Resources Information Center
Manolov, Rumen; Solanas, Antonio; Bulte, Isis; Onghena, Patrick
2010-01-01
This study deals with the statistical properties of a randomization test applied to an ABAB design in cases where the desirable random assignment of the points of change in phase is not possible. To obtain information about each possible data division, the authors carried out a conditional Monte Carlo simulation with 100,000 samples for each…
The robust design for capture-recapture studies: analysis using program MARK
Kendall, W.L.
2001-01-01
Collecting capture-recapture data under Pollock?s robust design provides an additional source of information on capture probability that can be used to provide less biased and more efficient estimates of population dynamics parameters. In addition, it can be used to estimate the probability of being available for capture, which in some cases (e.g., breeding proportion) has ecological significance. This phenomenon can be modeled as a completely random process, Markovian, or with temporary trap dependence. Analysis of this type of data is one of the options in program MARK. By using MARK the relationship between parameters and covariates can be modeled, and various approaches to goodness of fit, model selection, and model averaging can be implemented.
Use of Taguchi design of experiments to optimize and increase robustness of preliminary designs
NASA Technical Reports Server (NTRS)
Carrasco, Hector R.
1992-01-01
The research performed this summer includes the completion of work begun last summer in support of the Air Launched Personnel Launch System parametric study, providing support on the development of the test matrices for the plume experiments in the Plume Model Investigation Team Project, and aiding in the conceptual design of a lunar habitat. After the conclusion of last years Summer Program, the Systems Definition Branch continued with the Air Launched Personnel Launch System (ALPLS) study by running three experiments defined by L27 Orthogonal Arrays. Although the data was evaluated during the academic year, the analysis of variance and the final project review were completed this summer. The Plume Model Investigation Team (PLUMMIT) was formed by the Engineering Directorate to develop a consensus position on plume impingement loads and to validate plume flowfield models. In order to obtain a large number of individual correlated data sets for model validation, a series of plume experiments was planned. A preliminary 'full factorial' test matrix indicated that 73,024 jet firings would be necessary to obtain all of the information requested. As this was approximately 100 times more firings than the scheduled use of Vacuum Chamber A would permit, considerable effort was needed to reduce the test matrix and optimize it with respect to the specific objectives of the program. Part of the First Lunar Outpost Project deals with Lunar Habitat. Requirements for the habitat include radiation protection, a safe haven for occasional solar flare storms, an airlock module as well as consumables to support 34 extra vehicular activities during a 45 day mission. The objective for the proposed work was to collaborate with the Habitat Team on the development and reusability of the Logistics Modules.
Use of Taguchi design of experiments to optimize and increase robustness of preliminary designs
NASA Astrophysics Data System (ADS)
Carrasco, Hector R.
1992-12-01
The research performed this summer includes the completion of work begun last summer in support of the Air Launched Personnel Launch System parametric study, providing support on the development of the test matrices for the plume experiments in the Plume Model Investigation Team Project, and aiding in the conceptual design of a lunar habitat. After the conclusion of last years Summer Program, the Systems Definition Branch continued with the Air Launched Personnel Launch System (ALPLS) study by running three experiments defined by L27 Orthogonal Arrays. Although the data was evaluated during the academic year, the analysis of variance and the final project review were completed this summer. The Plume Model Investigation Team (PLUMMIT) was formed by the Engineering Directorate to develop a consensus position on plume impingement loads and to validate plume flowfield models. In order to obtain a large number of individual correlated data sets for model validation, a series of plume experiments was planned. A preliminary 'full factorial' test matrix indicated that 73,024 jet firings would be necessary to obtain all of the information requested. As this was approximately 100 times more firings than the scheduled use of Vacuum Chamber A would permit, considerable effort was needed to reduce the test matrix and optimize it with respect to the specific objectives of the program. Part of the First Lunar Outpost Project deals with Lunar Habitat. Requirements for the habitat include radiation protection, a safe haven for occasional solar flare storms, an airlock module as well as consumables to support 34 extra vehicular activities during a 45 day mission. The objective for the proposed work was to collaborate with the Habitat Team on the development and reusability of the Logistics Modules.
Kendall, W.L.; Nichols, J.D.; Hines, J.E.
1997-01-01
Statistical inference for capture-recapture studies of open animal populations typically relies on the assumption that all emigration from the studied population is permanent. However, there are many instances in which this assumption is unlikely to be met. We define two general models for the process of temporary emigration, completely random and Markovian. We then consider effects of these two types of temporary emigration on Jolly-Seber (Seber 1982) estimators and on estimators arising from the full-likelihood approach of Kendall et al. (1995) to robust design data. Capture-recapture data arising from Pollock's (1982) robust design provide the basis for obtaining unbiased estimates of demographic parameters in the presence of temporary emigration and for estimating the probability of temporary emigration. We present a likelihood-based approach to dealing with temporary emigration that permits estimation under different models of temporary emigration and yields tests for completely random and Markovian emigration. In addition, we use the relationship between capture probability estimates based on closed and open models under completely random temporary emigration to derive three ad hoc estimators for the probability of temporary emigration, two of which should be especially useful in situations where capture probabilities are heterogeneous among individual animals. Ad hoc and full-likelihood estimators are illustrated for small mammal capture-recapture data sets. We believe that these models and estimators will be useful for testing hypotheses about the process of temporary emigration, for estimating demographic parameters in the presence of temporary emigration, and for estimating probabilities of temporary emigration. These latter estimates are frequently of ecological interest as indicators of animal movement and, in some sampling situations, as direct estimates of breeding probabilities and proportions.
Hierarchical design of an electro-hydraulic actuator based on robust LPV methods
NASA Astrophysics Data System (ADS)
Németh, Balázs; Varga, Balázs; Gáspár, Péter
2015-08-01
The paper proposes a hierarchical control design of an electro-hydraulic actuator, which is used to improve the roll stability of vehicles. The purpose of the control system is to generate a reference torque, which is required by the vehicle dynamic control. The control-oriented model of the actuator is formulated in two subsystems. The high-level hydromotor is described in a linear form, while the low-level spool valve is a polynomial system. These subsystems require different control strategies. At the high level, a linear parameter-varying control is used to guarantee performance specifications. At the low level, a control Lyapunov-function-based algorithm, which creates discrete control input values of the valve, is proposed. The interaction between the two subsystems is guaranteed by the spool displacement, which is control input at the high level and must be tracked at the low-level control. The spool displacement has physical constraints, which must also be incorporated into the control design. The robust design of the high-level control incorporates the imprecision of the low-level control as an uncertainty of the system.
Modelling for the robust design of layered resonators for ultrasonic particle manipulation.
Hill, Martyn; Townsend, Rosemary J; Harris, Nicholas R
2008-11-01
Several approaches have been described for the manipulation of particles within an ultrasonic field. Of those based on standing waves, devices in which the critical dimension of the resonant chamber is less than a wavelength are particularly well suited to microfluidic, or "lab on a chip" applications. These might include pre-processing or fractionation of samples prior to analysis, formation of monolayers for cell interaction studies, or the enhancement of biosensor detection capability. The small size of microfluidic resonators typically places tight tolerances on the positioning of the acoustic node, and such systems are required to have high transduction efficiencies, for reasons of power availability and temperature stability. Further, the expense of many microfabrication methods precludes an iterative experimental approach to their development. Hence, the ability to design sub-wavelength resonators that are efficient, robust and have the appropriate acoustic energy distribution is extremely important. This paper discusses one-dimensional modelling used in the design of ultrasonic resonators for particle manipulation and gives example of their uses to predict and explain resonator behaviour. Particular difficulties in designing quarter wave systems are highlighted, and modelling is used to explain observed trends and predict performance of such resonators, including their performance with different coupling layer materials. PMID:18664398
Wavelet Domain Radiofrequency Pulse Design Applied to Magnetic Resonance Imaging
Huettner, Andrew M.; Mickevicius, Nikolai J.; Ersoz, Ali; Koch, Kevin M.; Muftuler, L. Tugan; Nencka, Andrew S.
2015-01-01
A new method for designing radiofrequency (RF) pulses with numerical optimization in the wavelet domain is presented. Numerical optimization may yield solutions that might otherwise have not been discovered with analytic techniques alone. Further, processing in the wavelet domain reduces the number of unknowns through compression properties inherent in wavelet transforms, providing a more tractable optimization problem. This algorithm is demonstrated with simultaneous multi-slice (SMS) spin echo refocusing pulses because reduced peak RF power is necessary for SMS diffusion imaging with high acceleration factors. An iterative, nonlinear, constrained numerical minimization algorithm was developed to generate an optimized RF pulse waveform. Wavelet domain coefficients were modulated while iteratively running a Bloch equation simulator to generate the intermediate slice profile of the net magnetization. The algorithm minimizes the L2-norm of the slice profile with additional terms to penalize rejection band ripple and maximize the net transverse magnetization across each slice. Simulations and human brain imaging were used to demonstrate a new RF pulse design that yields an optimized slice profile and reduced peak energy deposition when applied to a multiband single-shot echo planar diffusion acquisition. This method may be used to optimize factors such as magnitude and phase spectral profiles and peak RF pulse power for multiband simultaneous multi-slice (SMS) acquisitions. Wavelet-based RF pulse optimization provides a useful design method to achieve a pulse waveform with beneficial amplitude reduction while preserving appropriate magnetization response for magnetic resonance imaging. PMID:26517262
Wavelet Domain Radiofrequency Pulse Design Applied to Magnetic Resonance Imaging.
Huettner, Andrew M; Mickevicius, Nikolai J; Ersoz, Ali; Koch, Kevin M; Muftuler, L Tugan; Nencka, Andrew S
2015-01-01
A new method for designing radiofrequency (RF) pulses with numerical optimization in the wavelet domain is presented. Numerical optimization may yield solutions that might otherwise have not been discovered with analytic techniques alone. Further, processing in the wavelet domain reduces the number of unknowns through compression properties inherent in wavelet transforms, providing a more tractable optimization problem. This algorithm is demonstrated with simultaneous multi-slice (SMS) spin echo refocusing pulses because reduced peak RF power is necessary for SMS diffusion imaging with high acceleration factors. An iterative, nonlinear, constrained numerical minimization algorithm was developed to generate an optimized RF pulse waveform. Wavelet domain coefficients were modulated while iteratively running a Bloch equation simulator to generate the intermediate slice profile of the net magnetization. The algorithm minimizes the L2-norm of the slice profile with additional terms to penalize rejection band ripple and maximize the net transverse magnetization across each slice. Simulations and human brain imaging were used to demonstrate a new RF pulse design that yields an optimized slice profile and reduced peak energy deposition when applied to a multiband single-shot echo planar diffusion acquisition. This method may be used to optimize factors such as magnitude and phase spectral profiles and peak RF pulse power for multiband simultaneous multi-slice (SMS) acquisitions. Wavelet-based RF pulse optimization provides a useful design method to achieve a pulse waveform with beneficial amplitude reduction while preserving appropriate magnetization response for magnetic resonance imaging. PMID:26517262
NASA Astrophysics Data System (ADS)
Nakano, Kazuhiro; Obayashi, Masanao; Kuremoto, Takashi; Kobayashi, Kunikazu
We propose a robust control system which has robustness for disturbance and can deal with a nonlinear system with partially unknown structure by fusing reinforcement learning and robust control theory. First, we solved an optimal control problem without using unknown part of functions of the system, using neural network and the repetition learning of reinforcement learning algorithm. Second, we built the robust reinforcement learning control system which permits uncertainty and has robustness for disturbance by fusing the idea of H infinity control theory with above system.
NASA Technical Reports Server (NTRS)
Chen, Wei; Tsui, Kwok-Leung; Allen, Janet K.; Mistree, Farrokh
1994-01-01
In this paper we introduce a comprehensive and rigorous robust design procedure to overcome some limitations of the current approaches. A comprehensive approach is general enough to model the two major types of robust design applications, namely, robust design associated with the minimization of the deviation of performance caused by the deviation of noise factors (uncontrollable parameters), and robust design due to the minimization of the deviation of performance caused by the deviation of control factors (design variables). We achieve mathematical rigor by using, as a foundation, principles from the design of experiments and optimization. Specifically, we integrate the Response Surface Method (RSM) with the compromise Decision Support Problem (DSP). Our approach is especially useful for design problems where there are no closed-form solutions and system performance is computationally expensive to evaluate. The design of a solar powered irrigation system is used as an example. Our focus in this paper is on illustrating our approach rather than on the results per se.
Generation After Next Propulsor Research: Robust Design for Embedded Engine Systems
NASA Technical Reports Server (NTRS)
Arend, David J.; Tillman, Gregory; O'Brien, Walter F.
2012-01-01
The National Aeronautics and Space Administration, United Technologies Research Center and Virginia Polytechnic and State University have contracted to pursue multi-disciplinary research into boundary layer ingesting (BLI) propulsors for generation after next environmentally responsible subsonic fixed wing aircraft. This Robust Design for Embedded Engine Systems project first conducted a high-level vehicle system study based on a large commercial transport class hybrid wing body aircraft, which determined that a 3 to 5 percent reduction in fuel burn could be achieved over a 7,500 nanometer mission. Both pylon-mounted baseline and BLI propulsion systems were based on a low-pressure-ratio fan (1.35) in an ultra-high-bypass ratio engine (16), consistent with the next generation of advanced commercial turbofans. An optimized, coupled BLI inlet and fan system was subsequently designed to achieve performance targets identified in the system study. The resulting system possesses an inlet with total pressure losses less than 0.5%, and a fan stage with an efficiency debit of less than 1.5 percent relative to the pylon-mounted, clean-inflow baseline. The subject research project has identified tools and methodologies necessary for the design of next-generation, highly-airframe-integrated propulsion systems. These tools will be validated in future large-scale testing of the BLI inlet / fan system in NASA's 8 foot x 6 foot transonic wind tunnel. In addition, fan unsteady response to screen-generated total pressure distortion is being characterized experimentally in a JT15D engine test rig. These data will document engine sensitivities to distortion magnitude and spatial distribution, providing early insight into key physical processes that will control BLI propulsor design.
Design of Robust Guaranteed Cost PID Controller for Networked Control Systems
NASA Astrophysics Data System (ADS)
Nguyen, Quang Thuan; Veselý, Vojtech
2010-03-01
The paper addresses the problem of an output feedback guaranteed cost controller design for Networked Control Systems (NCSs) with time-delay and polytopic uncertainties. By constructing a new parameter-dependent Lyapunov functional and applying the free-weighting matrices technique, the parameter-dependent, delay-dependent design method will be obtained to synthesize PID controllers achieving a guaranteed cost such that the NCSs can be stabilized for all admissible uncertainties and time-delays. Finally, numerical examples are given to illustrate the effectiveness of the proposed method.
NASA Astrophysics Data System (ADS)
Whyte, D. G.; Bonoli, P.; Barnard, H.; Haakonsen, C.; Hartwig, Z.; Kasten, C.; Palmer, T.; Sung, C.; Sutherland, D.; Bromberg, L.; Mangiarotti, F.; Goh, J.; Sorbom, B.; Sierchio, J.; Ball, J.; Greenwald, M.; Olynyk, G.; Minervini, J.
2012-10-01
Two of the greatest challenges to tokamak reactors are 1) large single-unit cost of each reactor's construction and 2) their susceptibility to disruptions from operation at or above operational limits. We present an attractive tokamak reactor design that substantially lessens these issues by exploiting recent advancements in superconductor (SC) tapes allowing peak field on SC coil > 20 Tesla. A R˜3.3 m, B˜9.2 T, ˜ 500 MW fusion power tokamak provides high fusion gain while avoiding all disruptive operating boundaries (no-wall beta, kink, and density limits). Robust steady-state core scenarios are obtained by exploiting the synergy of high field, compact size and ideal efficiency current drive using high-field side launch of Lower Hybrid waves. The design features a completely modular replacement of internal solid components enabled by the demountability of the coils/tapes and the use of an immersion liquid blanket. This modularity opens up the possibility of using the device as a nuclear component test facility.
Design, stability and robustness analyses of neural networks in control systems
NASA Astrophysics Data System (ADS)
Shen, Jie
1998-12-01
Artificial Neural Network (ANN), also known as connectionist learning and parallel distributed processing, is finding its applications in diverse fields: many branches of engineering, health sciences, cognitive science, archaeology, finance, etc. This research tries to make some efforts to emphasize "design" methodology in ANN, and to explore the structures by which ANN can solve difficult problems by identifying proper ANN architecture. Two classes of ANN--multi-layer neural networks and recurrent networks--are investigated in the context of control of systems and estimation of unknown parameters. The multi-layer neural networks converge to optimal solutions by satisfying mathematical formulations associated with the Hamilton approach and the dynamic programming approach. A benchmark aerospace application is used for illustration. A variant of the Hopfield network, called the Modified Hopfield Neural Network (MHNN), is proposed to show the design approach to the determination of weights in recurrent networks. It is shown how the equilibrium point of this network helps with inversion operations arising in optimal gain determination. Control of dynamic systems using recurrent neural networks are presented. The robustness of the recurrent networks to parameter variation is considered in the context of weights. Analyses are carried out in the frequency domain and the time domain.
On the robust control of an induction machine: A complete design and realization
NASA Astrophysics Data System (ADS)
Chouiter, D. R.; Clerc, G.; Auriol, P.; Rétif, J. M.
1999-04-01
Electrical traction of vehicle needs accurate control of torque and flux. DC machines are mainly used but they are expensive and need heavy maintenance. Since some years, the use of field oriented vector control induction machines allows to fulfill the same objectives with lower cost. Unfortunately, they may present a decrease of their performances and an instability when their parameters vary with the temperature or the magnetic state and in the presence of converter or measurement noises. Therefore it is necessary to design effective control laws, which are especially less sensitive to these perturbations and variations. In this work, we have undertaken the conception and the realization of a voltage vector flux control whose inputs have been uncoupled by compensating terms. The torque and the flux regulations are realized at two different levels: an internal regulation loop for stator currents, and an external one for flux and torque. In order to achieve robust stability and performance objectives, we have involved several new methods in the domain such as H_{infty} control designed by genetic algorithms and reduced order extended Kalman filtering in the synchronous frame. Simulations will show the method efficiency and experimental results validate the control strategy.
NASA Technical Reports Server (NTRS)
Postma, Barry Dirk
2005-01-01
This thesis discusses application of a robust constrained optimization approach to control design to develop an Auto Balancing Controller (ABC) for a centrifuge rotor to be implemented on the International Space Station. The design goal is to minimize a performance objective of the system, while guaranteeing stability and proper performance for a range of uncertain plants. The Performance objective is to minimize the translational response of the centrifuge rotor due to a fixed worst-case rotor imbalance. The robustness constraints are posed with respect to parametric uncertainty in the plant. The proposed approach to control design allows for both of these objectives to be handled within the framework of constrained optimization. The resulting controller achieves acceptable performance and robustness characteristics.
SU-E-T-266: Proton PBS Plan Design and Robustness Evaluation for Head and Neck Cancers
Liang, X; Tang, S; Zhai, H; Kirk, M; Kalbasi, A; Lin, A; Ahn, P; Tochner, Z; McDonough, J; Both, S
2014-06-01
Purpose: To describe a newly designed proton pencil beam scanning (PBS) planning technique for radiotherapy of patients with bilateral oropharyngeal cancer, and to assess plan robustness. Methods: We treated 10 patients with proton PBS plans using 2 posterior oblique field (2F PBS) comprised of 80% single-field uniform dose (SFUD) and 20% intensity-modulated proton therapy (IMPT). All patients underwent weekly CT scans for verification. Using dosimetric indicators for both targets and organs at risk (OARs), we quantitatively compared initial plans and verification plans using student t-tests. We created a second proton PBS plan for each patient using 2 posterior oblique plus 1 anterior field comprised of 100% SFUD (3F PBS). We assessed plan robustness for both proton plan groups, as well as a photon volumetric modulated arc therapy (VMAT) plan group by comparing initial and verification plans. Results: The 2F PBS plans were not robust in target coverage. D98% for clinical target volume (CTV) degraded from 100% to 96% on average, with maximum change Δ D98% of −24%. Two patients were moved to photon VMAT treatment due to insufficient CTV coverage on verification plans. Plan robustness was especially weak in the low-anterior neck. The 3F PBS plans, however, demonstrated robust target coverage, which was comparable to the VMAT photon plan group. Doses to oral cavity were lower in the Proton PBS plans compared to photon VMAT plans due to no lower exit dose to the oral cavity. Conclusion: Proton PBS plans using 2 posterior oblique fields were not robust for CTV coverage, due to variable positioning of redundant soft tissue in the posterior neck. We designed 3-field proton PBS plans using an anterior field to avoid long heterogeneous paths in the low neck. These 3-field proton PBS plans had significantly improved plan robustness, and the robustness is comparable to VMAT photon plans.
Parametric Design within an Atomic Design Process (ADP) applied to Spacecraft Design
NASA Astrophysics Data System (ADS)
Ramos Alarcon, Rafael
This thesis describes research investigating the development of a model for the initial design of complex systems, with application to spacecraft design. The design model is called an atomic design process (ADP) and contains four fundamental stages (specifications, configurations, trade studies and drivers) that constitute the minimum steps of an iterative process that helps designers find a feasible solution. Representative design models from the aerospace industry are reviewed and are compared with the proposed model. The design model's relevance, adaptability and scalability features are evaluated through a focused design task exercise with two undergraduate teams and a long-term design exercise performed by a spacecraft payload team. The implementation of the design model is explained in the context in which the model has been researched. This context includes the organization (a student-run research laboratory at the University of Michigan), its culture (academically oriented), members that have used the design model and the description of the information technology elements meant to provide support while using the model. This support includes a custom-built information management system that consolidates relevant information that is currently being used in the organization. The information is divided in three domains: personnel development history, technical knowledge base and laboratory operations. The focused study with teams making use of the design model to complete an engineering design exercise consists of the conceptual design of an autonomous system, including a carrier and a deployable lander that form the payload of a rocket with an altitude range of over 1000 meters. Detailed results from each of the stages of the design process while implementing the model are presented, and an increase in awareness of good design practices in the teams while using the model are explained. A long-term investigation using the design model consisting of the
Chen, Bor-Sen; Chang, Yu-Te; Wang, Yu-Chao
2008-02-01
Molecular noises in gene networks come from intrinsic fluctuations, transmitted noise from upstream genes, and the global noise affecting all genes. Knowledge of molecular noise filtering in gene networks is crucial to understand the signal processing in gene networks and to design noise-tolerant gene circuits for synthetic biology. A nonlinear stochastic dynamic model is proposed in describing a gene network under intrinsic molecular fluctuations and extrinsic molecular noises. The stochastic molecular-noise-processing scheme of gene regulatory networks for attenuating these molecular noises is investigated from the nonlinear robust stabilization and filtering perspective. In order to improve the robust stability and noise filtering, a robust gene circuit design for gene networks is proposed based on the nonlinear robust H infinity stochastic stabilization and filtering scheme, which needs to solve a nonlinear Hamilton-Jacobi inequality. However, in order to avoid solving these complicated nonlinear stabilization and filtering problems, a fuzzy approximation method is employed to interpolate several linear stochastic gene networks at different operation points via fuzzy bases to approximate the nonlinear stochastic gene network. In this situation, the method of linear matrix inequality technique could be employed to simplify the gene circuit design problems to improve robust stability and molecular-noise-filtering ability of gene networks to overcome intrinsic molecular fluctuations and extrinsic molecular noises. PMID:18270080
Lee, Ji Min; Park, Sung Hwan; Kim, Jong Shik
2013-01-01
A robust control scheme is proposed for the position control of the electrohydrostatic actuator (EHA) when considering hardware saturation, load disturbance, and lumped system uncertainties and nonlinearities. To reduce overshoot due to a saturation of electric motor and to realize robustness against load disturbance and lumped system uncertainties such as varying parameters and modeling error, this paper proposes an adaptive antiwindup PID sliding mode scheme as a robust position controller for the EHA system. An optimal PID controller and an optimal anti-windup PID controller are also designed to compare control performance. An EHA prototype is developed, carrying out system modeling and parameter identification in designing the position controller. The simply identified linear model serves as the basis for the design of the position controllers, while the robustness of the control systems is compared by experiments. The adaptive anti-windup PID sliding mode controller has been found to have the desired performance and become robust against hardware saturation, load disturbance, and lumped system uncertainties and nonlinearities. PMID:23983640
Reduced-Order Blade Mistuning Analysis Techniques Developed for the Robust Design of Engine Rotors
NASA Technical Reports Server (NTRS)
Min, James B.
2004-01-01
The primary objective of this research program is to develop vibration analysis tools, design tools, and design strategies to significantly improve the safety and robustness of turbine engine rotors. Bladed disks in turbine engines always feature small, random blade-to-blade differences, or mistuning. Mistuning can lead to a dramatic increase in blade forced-response amplitudes and stresses. Ultimately, this results in high-cycle fatigue, which is a major safety and cost concern. In this research program, the necessary steps will be taken to transform a state-of-the-art vibration analysis tool, the Turbo-Reduce forced-response prediction code, into an effective design tool by enhancing and extending the underlying modeling and analysis methods. Furthermore, novel techniques will be developed to assess the safety of a given design. In particular, a procedure will be established for using eigenfrequency curve veerings to identify "danger zones" in the operating conditions--ranges of rotational speeds and engine orders in which there is a great risk that the rotor blades will suffer high stresses. This work also will aid statistical studies of the forced response by reducing the necessary number of simulations. Finally, new strategies for improving the design of rotors will be pursued. Several methods will be investigated, including the use of intentional mistuning patterns to mitigate the harmful effects of random mistuning, and the modification of disk stiffness to avoid reaching critical values of interblade coupling in the desired operating range. Recent research progress is summarized in the following paragraphs. First, significant progress was made in the development of the component mode mistuning (CMM) and static mode compensation (SMC) methods for reduced-order modeling of mistuned bladed disks (see the following figure). The CMM method has been formalized and extended to allow a general treatment of mistuning. In addition, CMM allows individual mode
Object Design: Twelve Concepts to Know, Understand and Apply
ERIC Educational Resources Information Center
Marschalek, Douglas G.
2005-01-01
Some art teachers say that art is all around us when they actually mean that "design" is all around us. The everyday objects we view, purchase, and use are designed. Some are well designed, others are poorly designed, and many are in-between. Teachers need to develop learning strategies that enable their students to understand how design is part…
The Study of an Optimal Robust Design and Adjustable Ordering Strategies in the HSCM.
Liao, Hung-Chang; Chen, Yan-Kwang; Wang, Ya-huei
2015-01-01
The purpose of this study was to establish a hospital supply chain management (HSCM) model in which three kinds of drugs in the same class and with the same indications were used in creating an optimal robust design and adjustable ordering strategies to deal with a drug shortage. The main assumption was that although each doctor has his/her own prescription pattern, when there is a shortage of a particular drug, the doctor may choose a similar drug with the same indications as a replacement. Four steps were used to construct and analyze the HSCM model. The computation technology used included a simulation, a neural network (NN), and a genetic algorithm (GA). The mathematical methods of the simulation and the NN were used to construct a relationship between the factor levels and performance, while the GA was used to obtain the optimal combination of factor levels from the NN. A sensitivity analysis was also used to assess the change in the optimal factor levels. Adjustable ordering strategies were also developed to prevent drug shortages. PMID:26451162
The Study of an Optimal Robust Design and Adjustable Ordering Strategies in the HSCM
Liao, Hung-Chang; Chen, Yan-Kwang; Wang, Ya-huei
2015-01-01
The purpose of this study was to establish a hospital supply chain management (HSCM) model in which three kinds of drugs in the same class and with the same indications were used in creating an optimal robust design and adjustable ordering strategies to deal with a drug shortage. The main assumption was that although each doctor has his/her own prescription pattern, when there is a shortage of a particular drug, the doctor may choose a similar drug with the same indications as a replacement. Four steps were used to construct and analyze the HSCM model. The computation technology used included a simulation, a neural network (NN), and a genetic algorithm (GA). The mathematical methods of the simulation and the NN were used to construct a relationship between the factor levels and performance, while the GA was used to obtain the optimal combination of factor levels from the NN. A sensitivity analysis was also used to assess the change in the optimal factor levels. Adjustable ordering strategies were also developed to prevent drug shortages. PMID:26451162
Optimized CVD production of CNT-based nanohybrids by Taguchi robust design.
Santangelo, S; Lanza, M; Piperopoulos, E; Milone, C
2012-03-01
Taguchi's robust design method is for the first time employed to optimize many aspects of the production of nanohybrids based on C nanotubes by iron-catalyzed chemical vapor deposition in i-C4H10 + H2 atmosphere. By analyzing the outcomes of the catalytic process in terms of selectivity, carbon yield, purity and crystalline arrangement of the hybrid-forming nanotubes, the influence is ranked of the following parameters: synthesis temperature (500-700 degrees C), support material (alumina, magnesia or sodium-exchanged montmorillonite), calcination- (450-750 degrees C) and reduction-(500-700 degrees C) temperatures of the 15 wt% Fe-catalyst. In the experiments initially performed for this purpose, the growth process had, on average, scarce selectivity (2 in a scale 1-5) and poor yield (130 wt%); carbonaceous deposits exhibited unsatisfactory graphitization degree (Raman D/G intensity ratio > 1.5) and contained large amounts of metal impurities (14 wt%) and amorphous carbon (5 wt%). The indications emerging from Taguchi approach to the process optimization are critically examined. The experimental conditions chosen for carrying out test experiments allow achieving excellent selectivity (5) or large yield (760 wt%), hybrids with well-graphitized nanotubes (D/G intensity ratio < 0.6), nearly free of metallic (0.3 wt%) or amorphous (0.4 wt%) inclusions, with consequent possibility of satisfying the different requisites that the specific application to be addressed may require. PMID:22755069
A less field-intensive robust design for estimating demographic parameters with Mark-resight data
McClintock, B.T.; White, Gary C.
2009-01-01
The robust design has become popular among animal ecologists as a means for estimating population abundance and related demographic parameters with mark-recapture data. However, two drawbacks of traditional mark-recapture are financial cost and repeated disturbance to animals. Mark-resight methodology may in many circumstances be a less expensive and less invasive alternative to mark-recapture, but the models developed to date for these data have overwhelmingly concentrated only on the estimation of abundance. Here we introduce a mark-resight model analogous to that used in mark-recapture for the simultaneous estimation of abundance, apparent survival, and transition probabilities between observable and unobservable states. The model may be implemented using standard statistical computing software, but it has also been incorporated into the freeware package Program MARK. We illustrate the use of our model with mainland New Zealand Robin (Petroica australis) data collected to ascertain whether this methodology may be a reliable alternative for monitoring endangered populations of a closely related species inhabiting the Chatham Islands. We found this method to be a viable alternative to traditional mark-recapture when cost or disturbance to species is of particular concern in long-term population monitoring programs. ?? 2009 by the Ecological Society of America.
Younkin, James R; Rowe, Nathan C; Garner, James R
2012-01-01
An online enrichment monitor (OLEM) is being developed to continuously measure the relative isotopic composition of UF6 in the unit header pipes of a gas centrifuge enrichment plant (GCEP). From a safeguards perspective, OLEM will provide early detection of a facility being misused for production of highly enriched uranium. OLEM may also reduce the number of samples collected for destructive assay and if coupled with load cell monitoring can provide isotope mass balance verification. The OLEM design includes power and network connections for continuous monitoring of the UF6 enrichment and state of health of the instrument. Monitoring the enrichment on all header pipes at a typical GCEP could require OLEM detectors on each of the product, tails, and feed header pipes. If there are eight process units, up to 24 detectors may be required at a modern GCEP. Distant locations, harsh industrial environments, and safeguards continuity of knowledge requirements all place certain demands on the network robustness and power reliability. This paper describes the infrastructure and architecture of an OLEM system based on OLEM collection nodes on the unit header pipes and power and network support nodes for groupings of the collection nodes. A redundant, self-healing communications network, distributed backup power, and a secure communications methodology. Two candidate technologies being considered for secure communications are the Object Linking and Embedding for Process Control Unified Architecture cross-platform, service-oriented architecture model for process control communications and the emerging IAEA Real-time And INtegrated STream-Oriented Remote Monitoring (RAINSTORM) framework to provide the common secure communication infrastructure for remote, unattended monitoring systems. The proposed infrastructure design offers modular, commercial components, plug-and-play extensibility for GCEP deployments, and is intended to meet the guidelines and requirements for unattended
Carmena, Jose M.
2016-01-01
Much progress has been made in brain-machine interfaces (BMI) using decoders such as Kalman filters and finding their parameters with closed-loop decoder adaptation (CLDA). However, current decoders do not model the spikes directly, and hence may limit the processing time-scale of BMI control and adaptation. Moreover, while specialized CLDA techniques for intention estimation and assisted training exist, a unified and systematic CLDA framework that generalizes across different setups is lacking. Here we develop a novel closed-loop BMI training architecture that allows for processing, control, and adaptation using spike events, enables robust control and extends to various tasks. Moreover, we develop a unified control-theoretic CLDA framework within which intention estimation, assisted training, and adaptation are performed. The architecture incorporates an infinite-horizon optimal feedback-control (OFC) model of the brain’s behavior in closed-loop BMI control, and a point process model of spikes. The OFC model infers the user’s motor intention during CLDA—a process termed intention estimation. OFC is also used to design an autonomous and dynamic assisted training technique. The point process model allows for neural processing, control and decoder adaptation with every spike event and at a faster time-scale than current decoders; it also enables dynamic spike-event-based parameter adaptation unlike current CLDA methods that use batch-based adaptation on much slower adaptation time-scales. We conducted closed-loop experiments in a non-human primate over tens of days to dissociate the effects of these novel CLDA components. The OFC intention estimation improved BMI performance compared with current intention estimation techniques. OFC assisted training allowed the subject to consistently achieve proficient control. Spike-event-based adaptation resulted in faster and more consistent performance convergence compared with batch-based methods, and was robust to
Shanechi, Maryam M; Orsborn, Amy L; Carmena, Jose M
2016-04-01
Much progress has been made in brain-machine interfaces (BMI) using decoders such as Kalman filters and finding their parameters with closed-loop decoder adaptation (CLDA). However, current decoders do not model the spikes directly, and hence may limit the processing time-scale of BMI control and adaptation. Moreover, while specialized CLDA techniques for intention estimation and assisted training exist, a unified and systematic CLDA framework that generalizes across different setups is lacking. Here we develop a novel closed-loop BMI training architecture that allows for processing, control, and adaptation using spike events, enables robust control and extends to various tasks. Moreover, we develop a unified control-theoretic CLDA framework within which intention estimation, assisted training, and adaptation are performed. The architecture incorporates an infinite-horizon optimal feedback-control (OFC) model of the brain's behavior in closed-loop BMI control, and a point process model of spikes. The OFC model infers the user's motor intention during CLDA-a process termed intention estimation. OFC is also used to design an autonomous and dynamic assisted training technique. The point process model allows for neural processing, control and decoder adaptation with every spike event and at a faster time-scale than current decoders; it also enables dynamic spike-event-based parameter adaptation unlike current CLDA methods that use batch-based adaptation on much slower adaptation time-scales. We conducted closed-loop experiments in a non-human primate over tens of days to dissociate the effects of these novel CLDA components. The OFC intention estimation improved BMI performance compared with current intention estimation techniques. OFC assisted training allowed the subject to consistently achieve proficient control. Spike-event-based adaptation resulted in faster and more consistent performance convergence compared with batch-based methods, and was robust to parameter
Our objective is to determine an optimal experimental design for a mixture of perfluoroalkyl acids (PFAAs) that is robust to the assumption of additivity. PFAAs are widely used in consumer products and industrial applications. The presence and persistence of PFAAs, especially in ...
Our objective was to determine an optimal experimental design for a mixture of perfluoroalkyl acids (PFAAs) that is robust to the assumption of additivity. Of particular focus to this research project is whether an environmentally relevant mixture of four PFAAs with long half-liv...
ERIC Educational Resources Information Center
King, Gary; Gakidou, Emmanuela; Ravishankar, Nirmala; Moore, Ryan T.; Lakin, Jason; Vargas, Manett; Tellez-Rojo, Martha Maria; Avila, Juan Eugenio Hernandez; Avila, Mauricio Hernandez; Llamas, Hector Hernandez
2007-01-01
We develop an approach to conducting large-scale randomized public policy experiments intended to be more robust to the political interventions that have ruined some or all parts of many similar previous efforts. Our proposed design is insulated from selection bias in some circumstances even if we lose observations; our inferences can still be…
Design of diode-pumped solid-state laser applied in laser fuses
NASA Astrophysics Data System (ADS)
Deng, FangLin; Zhang, YiFei
2005-04-01
The function of laser fuzes which are parts of certain weapon systems is to control the blasting height of warheads. Commonly the battle environment these weapon systems are confronted with is very complicated and the tactical demand for them is very rigor, so laser fuzes equipped for them must fulfill some special technical requirements, such as high repetition rate, long ranging scope, etc. Lasers are one of key components which constitute fuze systems. Whether designed lasers are advanced and reasonable will determine whether laser fuzes can be applied in these weapon systems or not. So we adopt the novel technology of diode-pumped solid-state laser (DPSSL) to design lasers applied in fuzes. Nd:YVO4 crystal is accepted as gain material, which has wide absorption band and large absorption efficient for 808nm pumping laser. As warhead's temperature is usually very high, wider absorption band is beneficial to reduce the influence of temperature fluctuation. Passive Q-switching with Cr4+:YAG is used to reduce the power consumption farthest. Design the end-pumped microchip sandwich-architecture to decrease lasers' size and increase the reliability, further it's advantageous to produce short pulses and increase peak power of lasers. The designed DPSSL features small size and weight, high repetition rate and peak power, robustness, etc. The repetition rate is expected to reach 1 kHz; peak power will exceed 300 kW; pulse width is only 5 ns; and divergence angle of laser beams is less than 5 mrad. So DPSSL is suitable for laser fuzes as an emitter.
Robust reliable control design for networked control system with sampling communication
NASA Astrophysics Data System (ADS)
Sakthivel, R.; Santra, Srimanta; Mathiyalagan, K.; Su, Hongye
2015-12-01
In this article, the problem of robust exponential stability and reliable stabilisation for a class of continuous-time networked control systems (NCSs) with a sample-data controller and unknown time-varying sampling rate is considered. The analysis is based on average dwell-time, Lyapunov-Krasovskii functional and linear matrix inequality (LMI) technique. The delay-dependent criteria are developed for ensuring the robust exponential stability of the considered NCSs. The obtained conditions are formulated in terms of LMIs that can easily be solved by using standard software packages. Furthermore, the result is extended to study the robust stabilisation for NCS with parameter uncertainties. A state feedback controller is constructed in terms of the solution to a set of LMIs, which guarantee the robust exponential stabilisation of NCS and the controller. Finally, numerical examples are presented to illustrate the effectiveness of the obtained results.
Approach for Input Uncertainty Propagation and Robust Design in CFD Using Sensitivity Derivatives
NASA Technical Reports Server (NTRS)
Putko, Michele M.; Taylor, Arthur C., III; Newman, Perry A.; Green, Lawrence L.
2002-01-01
An implementation of the approximate statistical moment method for uncertainty propagation and robust optimization for quasi 3-D Euler CFD code is presented. Given uncertainties in statistically independent, random, normally distributed input variables, first- and second-order statistical moment procedures are performed to approximate the uncertainty in the CFD output. Efficient calculation of both first- and second-order sensitivity derivatives is required. In order to assess the validity of the approximations, these moments are compared with statistical moments generated through Monte Carlo simulations. The uncertainties in the CFD input variables are also incorporated into a robust optimization procedure. For this optimization, statistical moments involving first-order sensitivity derivatives appear in the objective function and system constraints. Second-order sensitivity derivatives are used in a gradient-based search to successfully execute a robust optimization. The approximate methods used throughout the analyses are found to be valid when considering robustness about input parameter mean values.
Juefei-Xu, Felix; Luu, Khoa; Savvides, Marios
2015-12-01
In this paper, we investigate a single-sample periocular-based alignment-robust face recognition technique that is pose-tolerant under unconstrained face matching scenarios. Our Spartans framework starts by utilizing one single sample per subject class, and generate new face images under a wide range of 3D rotations using the 3D generic elastic model which is both accurate and computationally economic. Then, we focus on the periocular region where the most stable and discriminant features on human faces are retained, and marginalize out the regions beyond the periocular region since they are more susceptible to expression variations and occlusions. A novel facial descriptor, high-dimensional Walsh local binary patterns, is uniformly sampled on facial images with robustness toward alignment. During the learning stage, subject-dependent advanced correlation filters are learned for pose-tolerant non-linear subspace modeling in kernel feature space followed by a coupled max-pooling mechanism which further improve the performance. Given any unconstrained unseen face image, the Spartans can produce a highly discriminative matching score, thus achieving high verification rate. We have evaluated our method on the challenging Labeled Faces in the Wild database and solidly outperformed the state-of-the-art algorithms under four evaluation protocols with a high accuracy of 89.69%, a top score among image-restricted and unsupervised protocols. The advancement of Spartans is also proven in the Face Recognition Grand Challenge and Multi-PIE databases. In addition, our learning method based on advanced correlation filters is much more effective, in terms of learning subject-dependent pose-tolerant subspaces, compared with many well-established subspace methods in both linear and non-linear cases. PMID:26285149
Applying Quality Function Deployment in Industrial Design Curriculum Planning
ERIC Educational Resources Information Center
Liu, Shuo-Fang; Lee, Yann-Long; Lin, Yi-Zhi; Tseng, Chien-Feng
2013-01-01
Industrial design is a discipline that combines multiple professional fields. Enterprise demands for industrial design competencies also change over time; thus, the curriculum of industrial design education should be compatible with the current demands of the industry. However, scientific approaches have not been previously employed to plan…
Designing a New Program in Family Relations and Applied Nutrition
ERIC Educational Resources Information Center
Devine, Sharon Mayne; Daly, Kerry; Lero, Donna; MacMartin, Clare
2007-01-01
Family Relations and Applied Nutrition, which is offered at the University of Guelph, is an interdisciplinary department that previously offered three undergraduate majors: child, youth, and family; applied human nutrition; and gerontology; as well as graduate programs at the master's and doctoral levels. Several factors have precipitated a review…
Managing Uncertainty in Water Infrastructure Design Using Info-gap Robustness
NASA Astrophysics Data System (ADS)
Irias, X.; Cicala, D.
2013-12-01
Info-gap theory, a tool for managing deep uncertainty, can be of tremendous value for design of water systems in areas of high seismic risk. Maintaining reliable water service in those areas is subject to significant uncertainties including uncertainty of seismic loading, unknown seismic performance of infrastructure, uncertain costs of innovative seismic-resistant construction, unknown costs to repair seismic damage, unknown societal impacts from downtime, and more. Practically every major earthquake that strikes a population center reveals additional knowledge gaps. In situations of such deep uncertainty, info-gap can offer advantages over traditional approaches, whether deterministic approaches that use empirical safety factors to address the uncertainties involved, or probabilistic methods that attempt to characterize various stochastic properties and target a compromise between cost and reliability. The reason is that in situations of deep uncertainty, it may not be clear what safety factor would be reasonable, or even if any safety factor is sufficient to address the uncertainties, and we may lack data to characterize the situation probabilistically. Info-gap is a tool that recognizes up front that our best projection of the future may be wrong. Thus, rather than seeking a solution that is optimal for that projection, info-gap seeks a solution that works reasonably well for all plausible conditions. In other words, info-gap seeks solutions that are robust in the face of uncertainty. Info-gap has been used successfully across a wide range of disciplines including climate change science, project management, and structural design. EBMUD is currently using info-gap to help it gain insight into possible solutions for providing reliable water service to an island community within its service area. The island, containing about 75,000 customers, is particularly vulnerable to water supply disruption from earthquakes, since it has negligible water storage and is
NASA Astrophysics Data System (ADS)
Karimi Movahed, Kamran; Zhang, Zhi-Hai
2015-09-01
Demand and lead time uncertainties have significant effects on supply chain behaviour. In this paper, we present a single-product three-level multi-period supply chain with uncertain demands and lead times by using robust techniques to study the managerial insights of the supply chain inventory system under uncertainty. We formulate this problem as a robust mixed-integer linear program with minimised expected cost and total cost variation to determine the optimal (s, S) values of the inventory parameters. Several numerical studies are performed to investigate the supply chain behaviour. Useful guidelines for the design of a robust supply chain are also provided. Results show that the order variance and the expected cost in a supply chain significantly increase when the manufacturer's review period is an integer ratio of the distributor's and the retailer's review periods.
NASA Astrophysics Data System (ADS)
Ngamroo, Issarachai
2010-12-01
It is well known that the superconducting magnetic energy storage (SMES) is able to quickly exchange active and reactive power with the power system. The SMES is expected to be the smart storage device for power system stabilization. Although the stabilizing effect of SMES is significant, the SMES is quite costly. Particularly, the superconducting magnetic coil size which is the essence of the SMES, must be carefully selected. On the other hand, various generation and load changes, unpredictable network structure, etc., cause system uncertainties. The power controller of SMES which is designed without considering such uncertainties, may not tolerate and loses stabilizing effect. To overcome these problems, this paper proposes the new design of robust SMES controller taking coil size and system uncertainties into account. The structure of the active and reactive power controllers is the 1st-order lead-lag compensator. No need for the exact mathematical representation, system uncertainties are modeled by the inverse input multiplicative perturbation. Without the difficulty of the trade-off of damping performance and robustness, the optimization problem of control parameters is formulated. The particle swarm optimization is used for solving the optimal parameters at each coil size automatically. Based on the normalized integral square error index and the consideration of coil current constraint, the robust SMES with the smallest coil size which still provides the satisfactory stabilizing effect, can be achieved. Simulation studies in the two-area four-machine interconnected power system show the superior robustness of the proposed robust SMES with the smallest coil size under various operating conditions over the non-robust SMES with large coil size.
Nichols, J.D.; Pollock, K.H.; Hines, J.E.
1984-01-01
The robust design of Pollock (1982) was used to estimate parameters of a Maryland M. pennsylvanicus population. Closed model tests provided strong evidence of heterogeneity of capture probability, and model M eta (Otis et al., 1978) was selected as the most appropriate model for estimating population size. The Jolly-Seber model goodness-of-fit test indicated rejection of the model for this data set, and the M eta estimates of population size were all higher than the Jolly-Seber estimates. Both of these results are consistent with the evidence of heterogeneous capture probabilities. The authors thus used M eta estimates of population size, Jolly-Seber estimates of survival rate, and estimates of birth-immigration based on a combination of the population size and survival rate estimates. Advantages of the robust design estimates for certain inference procedures are discussed, and the design is recommended for future small mammal capture-recapture studies directed at estimation.
Applying Universal Design for Learning to Instructional Lesson Planning
ERIC Educational Resources Information Center
McGhie-Richmond, Donna; Sung, Andrew N.
2013-01-01
Universal Design for Learning is a framework for developing inclusive instructional lesson plans. The effects of introducing Universal Design for Learning Principles and Guidelines in a university teacher education program with pre-service and practicing teachers were explored in a mixed methods approach. The results indicate that the study…
Applying learning theories and instructional design models for effective instruction.
Khalil, Mohammed K; Elkhider, Ihsan A
2016-06-01
Faculty members in higher education are involved in many instructional design activities without formal training in learning theories and the science of instruction. Learning theories provide the foundation for the selection of instructional strategies and allow for reliable prediction of their effectiveness. To achieve effective learning outcomes, the science of instruction and instructional design models are used to guide the development of instructional design strategies that elicit appropriate cognitive processes. Here, the major learning theories are discussed and selected examples of instructional design models are explained. The main objective of this article is to present the science of learning and instruction as theoretical evidence for the design and delivery of instructional materials. In addition, this article provides a practical framework for implementing those theories in the classroom and laboratory. PMID:27068989
Self-Adaptive Stepsize Search Applied to Optimal Structural Design
NASA Astrophysics Data System (ADS)
Nolle, L.; Bland, J. A.
Structural engineering often involves the design of space frames that are required to resist predefined external forces without exhibiting plastic deformation. The weight of the structure and hence the weight of its constituent members has to be as low as possible for economical reasons without violating any of the load constraints. Design spaces are usually vast and the computational costs for analyzing a single design are usually high. Therefore, not every possible design can be evaluated for real-world problems. In this work, a standard structural design problem, the 25-bar problem, has been solved using self-adaptive stepsize search (SASS), a relatively new search heuristic. This algorithm has only one control parameter and therefore overcomes the drawback of modern search heuristics, i.e. the need to first find a set of optimum control parameter settings for the problem at hand. In this work, SASS outperforms simulated-annealing, genetic algorithms, tabu search and ant colony optimization.
Nonlinear robust controller design for multi-robot systems with unknown payloads
NASA Technical Reports Server (NTRS)
Song, Y. D.; Anderson, J. N.; Homaifar, A.; Lai, H. Y.
1992-01-01
This work is concerned with the control problem of a multi-robot system handling a payload with unknown mass properties. Force constraints at the grasp points are considered. Robust control schemes are proposed that cope with the model uncertainty and achieve asymptotic path tracking. To deal with the force constraints, a strategy for optimally sharing the task is suggested. This strategy basically consists of two steps. The first detects the robots that need help and the second arranges that help. It is shown that the overall system is not only robust to uncertain payload parameters, but also satisfies the force constraints.
Approach for Uncertainty Propagation and Robust Design in CFD Using Sensitivity Derivatives
NASA Technical Reports Server (NTRS)
Putko, Michele M.; Newman, Perry A.; Taylor, Arthur C., III; Green, Lawrence L.
2001-01-01
This paper presents an implementation of the approximate statistical moment method for uncertainty propagation and robust optimization for a quasi 1-D Euler CFD (computational fluid dynamics) code. Given uncertainties in statistically independent, random, normally distributed input variables, a first- and second-order statistical moment matching procedure is performed to approximate the uncertainty in the CFD output. Efficient calculation of both first- and second-order sensitivity derivatives is required. In order to assess the validity of the approximations, the moments are compared with statistical moments generated through Monte Carlo simulations. The uncertainties in the CFD input variables are also incorporated into a robust optimization procedure. For this optimization, statistical moments involving first-order sensitivity derivatives appear in the objective function and system constraints. Second-order sensitivity derivatives are used in a gradient-based search to successfully execute a robust optimization. The approximate methods used throughout the analyses are found to be valid when considering robustness about input parameter mean values.
Designing IS Curricula for Practical Relevance: Applying Baseball's "Moneyball" Theory
ERIC Educational Resources Information Center
Surendra, Nanda C.; Denton, James W.
2009-01-01
Baseball's "Moneyball" theory states that the baseball market undervalues some attributes (and players with these attributes) that are key contributors to wins while overvaluing other attributes. Teams who correctly evaluate attributes that contribute to wins have higher winning percentages with relatively low payrolls. We applied the Moneyball…
Hou, Shibing; Wu, Jiang; Qin, Yufei; Xu, Zhenming
2010-07-01
Electrostatic separation is an effective and environmentally friendly method for recycling waste printed circuit board (PCB) by several kinds of electrostatic separators. However, some notable problems have been detected in its applications and cannot be efficiently resolved by optimizing the separation process. Instead of the separator itself, these problems are mainly caused by some external factors such as the nonconductive powder (NP) and the superficial moisture of feeding granule mixture. These problems finally lead to an inefficient separation. In the present research, the impacts of these external factors were investigated and a robust design was built to optimize the process and to weaken the adverse impact. A most robust parameter setting (25 kv, 80 rpm) was concluded from the experimental design. In addition, some theoretical methods, including cyclone separation, were presented to eliminate these problems substantially. This will contribute to efficient electrostatic separation of waste PCB and make remarkable progress for industrial applications. PMID:20518505
Bettotti, P; Mancinelli, M; Guider, R; Masi, M; Vanacharla, M Rao; Pavesi, L
2011-04-15
A novel (to our knowledge) scheme of an optical router/switch element, composed of a tapered side-coupled integrated spaced sequence of optical resonators, is proposed. It is based on a modified design of the ring sequence in which the resonance conditions are set by the single ring resonance and by the coherent feedback of the sequence of rings. This double condition yields robustness against fabrication defects, dense routing capability, and high switching efficiency. PMID:21499394
Applying Additive Manufacturing to a New Liquid Oxygen Turbopump Design
NASA Technical Reports Server (NTRS)
O'Neal, Derek
2016-01-01
A liquid oxygen turbopump has been designed at Marshall Space Flight Center as part of the in-house, Advanced Manufacturing Demonstrator Engine (AMDE) project. Additive manufacturing, specifically direct metal laser sintering (DMLS) of Inconel 718, is used for 77% of the parts by mass. These parts include the impeller, turbine components, and housings. The near-net shape DMLS parts have been delivered and final machining is underway. Fabrication of the traditionally manufactured hardware is also proceeding. Testing in liquid oxygen is planned for Q2 of FY2017. This topic explores the design of the turbopump along with fabrication and material testing of the DMLS hardware.
Applying Learning Theories and Instructional Design Models for Effective Instruction
ERIC Educational Resources Information Center
Khalil, Mohammed K.; Elkhider, Ihsan A.
2016-01-01
Faculty members in higher education are involved in many instructional design activities without formal training in learning theories and the science of instruction. Learning theories provide the foundation for the selection of instructional strategies and allow for reliable prediction of their effectiveness. To achieve effective learning…
A Probabilistic Design Method Applied to Smart Composite Structures
NASA Technical Reports Server (NTRS)
Shiao, Michael C.; Chamis, Christos C.
1995-01-01
A probabilistic design method is described and demonstrated using a smart composite wing. Probabilistic structural design incorporates naturally occurring uncertainties including those in constituent (fiber/matrix) material properties, fabrication variables, structure geometry and control-related parameters. Probabilistic sensitivity factors are computed to identify those parameters that have a great influence on a specific structural reliability. Two performance criteria are used to demonstrate this design methodology. The first criterion requires that the actuated angle at the wing tip be bounded by upper and lower limits at a specified reliability. The second criterion requires that the probability of ply damage due to random impact load be smaller than an assigned value. When the relationship between reliability improvement and the sensitivity factors is assessed, the results show that a reduction in the scatter of the random variable with the largest sensitivity factor (absolute value) provides the lowest failure probability. An increase in the mean of the random variable with a negative sensitivity factor will reduce the failure probability. Therefore, the design can be improved by controlling or selecting distribution parameters associated with random variables. This can be implemented during the manufacturing process to obtain maximum benefit with minimum alterations.
Control design and robustness analysis of a ball and plate system by using polynomial chaos
Colón, Diego; Balthazar, José M.; Reis, Célia A. dos; Bueno, Átila M.; Diniz, Ivando S.; Rosa, Suelia de S. R. F.
2014-12-10
In this paper, we present a mathematical model of a ball and plate system, a control law and analyze its robustness properties by using the polynomial chaos method. The ball rolls without slipping. There is an auxiliary robot vision system that determines the bodies' positions and velocities, and is used for control purposes. The actuators are to orthogonal DC motors, that changes the plate's angles with the ground. The model is a extension of the ball and beam system and is highly nonlinear. The system is decoupled in two independent equations for coordinates x and y. Finally, the resulting nonlinear closed loop systems are analyzed by the polynomial chaos methodology, which considers that some system parameters are random variables, and generates statistical data that can be used in the robustness analysis.
Control design and robustness analysis of a ball and plate system by using polynomial chaos
NASA Astrophysics Data System (ADS)
Colón, Diego; Balthazar, José M.; dos Reis, Célia A.; Bueno, Átila M.; Diniz, Ivando S.; de S. R. F. Rosa, Suelia
2014-12-01
In this paper, we present a mathematical model of a ball and plate system, a control law and analyze its robustness properties by using the polynomial chaos method. The ball rolls without slipping. There is an auxiliary robot vision system that determines the bodies' positions and velocities, and is used for control purposes. The actuators are to orthogonal DC motors, that changes the plate's angles with the ground. The model is a extension of the ball and beam system and is highly nonlinear. The system is decoupled in two independent equations for coordinates x and y. Finally, the resulting nonlinear closed loop systems are analyzed by the polynomial chaos methodology, which considers that some system parameters are random variables, and generates statistical data that can be used in the robustness analysis.
Large mode area aperiodic fiber designs for robust singlemode emission under high thermal load
NASA Astrophysics Data System (ADS)
Dauliat, Romain; Coscelli, Enrico; Poli, Federica; Darwich, Dia; Benoît, Aurélien; Jamier, Raphaël.; Schuster, Kay; Grimm, Stephan; Cucinotta, Annamaria; Selleri, Stefano; Salin, François; Roy, Philippe
2015-05-01
In this paper, we investigate the potential of various large mode area fibers under thermal load, that is the state-of-the-art air-silica large pitch fibers, as well as the recently devised symmetry-reduced photonic crystal fiber and aperiodic all-solid by carefully considering the degrees of freedom offered all along the fiber fabrication. This work aims to discuss the mode filtering ability of these structures in regard to the power scaling and to confirm their potential for robust singlemode operation at high power level. Structural principles contributing to improve their performances such as the impact of air holes / solid inclusions size will be presented. We also intend to establish that the range of average absorbed/output power for which a robust singlemode operation is available can be shifted to fulfill user requests in term of power range.
Flight control system design factors for applying automated testing techniques
NASA Technical Reports Server (NTRS)
Sitz, Joel R.; Vernon, Todd H.
1990-01-01
The principal design features and operational experiences of the X-29 forward-swept-wing aircraft and F-18 high alpha research vehicle (HARV) automated test systems are discussed. It is noted that operational experiences in developing and using these automated testing techniques have highlighted the need for incorporating target system features to improve testability. Improved target system testability can be accomplished with the addition of nonreal-time and real-time features. Online access to target system implementation details, unobtrusive real-time access to internal user-selectable variables, and proper software instrumentation are all desirable features of the target system. Also, test system and target system design issues must be addressed during the early stages of the target system development. Processing speeds of up to 20 million instructions/s and the development of high-bandwidth reflective memory systems have improved the ability to integrate the target system and test system for the application of automated testing techniques. It is concluded that new methods of designing testability into the target systems are required.
NASA Technical Reports Server (NTRS)
Avis, L. M.; Green, R. N.; Suttles, J. T.; Gupta, S. K.
1984-01-01
Computer simulations of a least squares estimator operating on the ERBE scanning channels are discussed. The estimator is designed to minimize the errors produced by nonideal spectral response to spectrally varying and uncertain radiant input. The three ERBE scanning channels cover a shortwave band a longwave band and a ""total'' band from which the pseudo inverse spectral filter estimates the radiance components in the shortwave band and a longwave band. The radiance estimator draws on instantaneous field of view (IFOV) scene type information supplied by another algorithm of the ERBE software, and on a priori probabilistic models of the responses of the scanning channels to the IFOV scene types for given Sun scene spacecraft geometry. It is found that the pseudoinverse spectral filter is stable, tolerant of errors in scene identification and in channel response modeling, and, in the absence of such errors, yields minimum variance and essentially unbiased radiance estimates.
[Information and communication technologies in teaching applied and experimental designs].
Bono, Roser; Arnau, Jaume; Blanca, María J
2006-08-01
In this work, an innovative teaching model applied to methodological contents in psychology is presented. The proposed didactic model includes Information and Communication Technologies (ICT), such as CD-ROMs, web sites and Internet. These resources complement class attendance. In the classes the students are informed, guided and oriented so that they are able to obtain information and reorganize it in a coherent way. The aim of this article is to find out the students' learning preferences and estimate the incorporation of ICT, by means of the ETIM (Evaluation of Teaching Innovation Model) questionnaire. The results show that the students are aware of the need to consult other materials and that ICT helps students to understand the subject from various perspectives. In this way, the students become more autonomous in acquiring learning results. PMID:17296099
Designing Crane Controls with applied Mechanical and Electrical Safety Features
NASA Technical Reports Server (NTRS)
Lytle, Bradford P.; Walczak, Thomas A.; Delgado, H. (Technical Monitor)
2002-01-01
The use of overhead traveling bridge cranes in many varied applications is common practice. In particular, the use of cranes in the nuclear, military, commercial, aerospace, and other industries can involve safety critical situations. Considerations for Human Injury or Casualty, Loss of Assets, Endangering the Environment, or Economic Reduction must be addressed. Traditionally, in order to achieve additional safety in these applications, mechanical systems have been augmented with a variety of devices. These devices assure that a mechanical component failure shall reduce the risk of a catastrophic loss of the correct and/or safe load carrying capability. ASME NOG-1-1998, (Rules for Construction of Overhead and Gantry Cranes, Top Running Bridge, and Multiple Girder), provides design standards for cranes in safety critical areas. Over and above the minimum safety requirements of todays design standards, users struggle with obtaining a higher degree of reliability through more precise functional specifications while attempting to provide "smart" safety systems. Electrical control systems also may be equipped with protective devices similar to the mechanical design features. Demands for improvement of the cranes "control system" is often recognized, but difficult to quantify for this traditionally "mechanically" oriented market. Finite details for each operation must be examined and understood. As an example, load drift (or small motions) at close tolerances can be unacceptable (and considered critical). To meet these high functional demands encoders and other devices are independently added to control systems to provide motion and velocity feedback to the control drive. This paper will examine the implementation of Programmable Electronic Systems (PES). PES is a term this paper will use to describe any control system utilizing any programmable electronic device such as Programmable Logic Controllers (PLC), or an Adjustable Frequency Drive (AID) 'smart' programmable
Optical design of low glare luminaire applied for tunnel light
NASA Astrophysics Data System (ADS)
Tsai, M. S.; Lee, X. H.; Lo, Y. C.; Sun, C. C.
2014-09-01
In this study, a low glare and high-efficient tunnel lighting design which consists of a cluster light-emitting diode and a free-form lens is presented. Most of the energy emitted from the proposed luminaire is transmitted onto the surface of the road in front of drivers, and the probability that the energy is emitted directly into drivers' eyes is low. Compared with traditional fluorescent lamps, the proposed luminaire, of which the optical utilization factor, optical efficiency, and uniformity are, respectively, 44%, 92.5%, and 0.72, performs favorably in traffic safety, energy saving, and glare reduction.
NASA Astrophysics Data System (ADS)
Ball, Nicholas M.; Brunner, Robert J.; Myers, Adam D.; Strand, Natalie E.; Alberts, Stacey L.; Tcheng, David; Llorà, Xavier
2007-07-01
We apply instance-based machine learning in the form of a k-nearest neighbor algorithm to the task of estimating photometric redshifts for 55,746 objects spectroscopically classified as quasars in the Fifth Data Release of the Sloan Digital Sky Survey. We compare the results obtained to those from an empirical color-redshift relation (CZR). In contrast to previously published results using CZRs, we find that the instance-based photometric redshifts are assigned with no regions of catastrophic failure. Remaining outliers are simply scattered about the ideal relation, in a manner similar to the pattern seen in the optical for normal galaxies at redshifts z<~1. The instance-based algorithm is trained on a representative sample of the data and pseudo-blind-tested on the remaining unseen data. The variance between the photometric and spectroscopic redshifts is σ2=0.123+/-0.002 (compared to σ2=0.265+/-0.006 for the CZR), and 54.9%+/-0.7%, 73.3%+/-0.6%, and 80.7%+/-0.3% of the objects are within Δz<0.1, 0.2, and 0.3, respectively. We also match our sample to the Second Data Release of the Galaxy Evolution Explorer legacy data, and the resulting 7642 objects show a further improvement, giving a variance of σ2=0.054+/-0.005, with 70.8%+/-1.2%, 85.8%+/-1.0%, and 90.8%+/-0.7% of objects within Δz<0.1, 0.2, and 0.3. We show that the improvement is indeed due to the extra information provided by GALEX, by training on the same data set using purely SDSS photometry, which has a variance of σ2=0.090+/-0.007. Each set of results represents a realistic standard for application to further data sets for which the spectra are representative.
APPLYING INSIGHTS FROM BEHAVIORAL ECONOMICS TO POLICY DESIGN
Madrian, Brigitte C.
2014-01-01
The premise of this article is that an understanding of psychology and other social science disciplines can inform the effectiveness of the economic tools traditionally deployed in carrying out the functions of government, which include remedying market failures, redistributing income, and collecting tax revenue. An understanding of psychology can also lead to the development of different policy tools that better motivate desired behavior change or that are more cost-effective than traditional policy tools. The article outlines a framework for thinking about the psychology of behavior change in the context of market failures. It then describes the research on the effects of a variety of interventions rooted in an understanding of psychology that have policy-relevant applications. The article concludes by discussing how an understanding of psychology can also inform the use and design of traditional policy tools for behavior change, such as financial incentives. PMID:25520759
Applying Contamination Modelling to Spacecraft Propulsion Systems Designs and Operations
NASA Technical Reports Server (NTRS)
Chen, Philip T.; Thomson, Shaun; Woronowicz, Michael S.
2000-01-01
Molecular and particulate contaminants generated from the operations of a propulsion system may impinge on spacecraft critical surfaces. Plume depositions or clouds may hinder the spacecraft and instruments from performing normal operations. Firing thrusters will generate both molecular and particulate contaminants. How to minimize the contamination impact from the plume becomes very critical for a successful mission. The resulting effect from either molecular or particulate contamination of the thruster firing is very distinct. This paper will discuss the interconnection between the functions of spacecraft contamination modeling and propulsion system implementation. The paper will address an innovative contamination engineering approach implemented from the spacecraft concept design, manufacturing, integration and test (I&T), launch, to on- orbit operations. This paper will also summarize the implementation on several successful missions. Despite other contamination sources, only molecular contamination will be considered here.
Applying Quality by Design Concepts to Pharmacy Compounding.
Timko, Robert J
2015-01-01
Compounding of medications is an important part of the practice of the pharmacy profession. Because compounded medications do not have U.S. Food and Drug Administration approval, a pharmacist has the responsibility to ensure that compounded medications are of suitable quality, safety, and efficacy. The Federal Government and numerous states have updated their laws and regulations regarding pharmacy compounding as a result of recent quality issues. Compounding pharmacists are expected to follow good preparation prodecures in their compounding practices in much the same way pharmaceutical manufacturers are required to follow Current Good Manufacturing Procedures as detailed in the United States Code of Federal Regulations. Application of Quality by Design concepts to the preparation process for a compounded medication can help in understanding the potential pitfalls and the means to mitigate their impact. The goal is to build quality into the compounding process to ensure that the resultant compounded prescription meets the human or animal patients' requirements. PMID:26891559
NASA Astrophysics Data System (ADS)
Lima, Roberta; Soize, Christian; Sampaio, Rubens
2015-06-01
In this paper, the robust design with an uncertain model of a vibro-impact electro-mechanical system is done. The electro-mechanical system is composed of a cart, whose motion is excited by a DC motor (motor with continuous current), and an embarked hammer into this cart. The hammer is connected to the cart by a nonlinear spring component and by a linear damper, so that a relative motion exists between them. A linear flexible barrier, placed outside of the cart, constrains the hammer movements. Due to the relative movement between the hammer and the barrier, impacts can occur between these two elements. The developed model of the system takes into account the influence of the DC motor in the dynamic behavior of the system. Some system parameters are uncertain, such as the stiffness and the damping coefficients of the flexible barrier. The objective of the paper is to perform an optimization of this electro-mechanical system with respect to design parameters (spring component, and barrier g) in order to maximize the impact power under the constraint that the electric power consumed by the DC motor is lower than a maximum value. This optimization is formulated in the framework of robust design due to the presence of uncertainties in the model. The set of nonlinear equations are presented, and an adapted time domain solver is developed. The stochastic nonlinear constrained design optimization problem is solved for different levels of uncertainties, and also for the deterministic case.
Applied design methodology for lunar rover elastic wheel
NASA Astrophysics Data System (ADS)
Cardile, Diego; Viola, Nicole; Chiesa, Sergio; Rougier, Alessandro
2012-12-01
In recent years an increasing interest in the Moon surface operations has been experienced. In the future robotic and manned missions of Moon surface exploration will be fundamental in order to lay the groundwork for more ambitious space exploration programs. Surface mobility systems will be the key elements to ensure an efficient and safe Moon exploration. Future lunar rovers are likely to be heavier and able to travel longer distances than the previously developed Moon rover systems. The Lunar Roving Vehicle (LRV) is the only manned rover, which has so far been launched and used on the Moon surface. Its mobility system included flexible wheels that cannot be scaled to the heavier and longer range vehicles. Thus the previously developed wheels are likely not to be suitable for the new larger vehicles. Taking all these considerations into account, on the basis of the system requirements and assumptions, several wheel concepts have been discussed and evaluated through a trade-off analysis. Semi-empirical equations have been utilized to predict the wheel geometrical characteristics, as well as to estimate the motion resistances and the ability of the system to generate thrust. A numerical model has also been implemented, in order to define more into the details the whole wheel design, in terms of wheel geometry and physical properties. As a result of the trade-off analysis, the ellipse wheel concept has shown the best behavior in terms of stiffness, mass budget and dynamic performance. The results presented in the paper have been obtained in cooperation with Thales Alenia Space-Italy and Sicme motori, in the framework of a regional program called STEPS . STEPS-Sistemi e Tecnologie per l'EsPlorazione Spaziale is a research project co-financed by Piedmont Region and firms and universities of the Piedmont Aerospace District in the ambit of the P.O.R-F.E.S.R. 2007-2013 program.
Applying environmental product design to biomedical products research.
Messelbeck, J; Sutherland, L
2000-12-01
The principal themes for the Biomedical Research and the Environment Conference Committee on Environmental Economics in Biomedical Research include the following: healthcare delivery companies and biomedical research organizations, both nonprofit and for-profit, need to improve their environmental performance; suppliers of healthcare products will be called upon to support this need; and improving the environmental profile of healthcare products begins in research and development (R&D). The committee report begins with requirements from regulatory authorities (e.g., U.S. Environmental Protection Agency [EPA], the U.S. Food and Drug Administration), and the healthcare delivery sector). The 1998 American Hospital Association and EPA Memorandum of Understanding to reduce solid waste and mercury from healthcare facilities is emblematic of these requirements. The dominant message from the requirements discussion is to ensure that R&D organizations do not ignore customer, environmental, and regulatory requirements in the early stages of product development. Several representatives from healthcare products manufacturers presented their companies' approaches to meeting these requirements. They reported on efforts to ensure that their R&D processes are sensitive to the environmental consequences from manufacturing, distributing, using, and disposing of healthcare products. These reports describe representatives' awareness of requirements and the unique approaches their R&D organizations have taken to meet these requirements. All representatives reported that their R&D organizations have embraced environmental product design because it avoids the potential of returning products to R&D to improve the environmental profile. Additionally, several reports detailed cost savings, sustainability benefits, and improvements in environmental manufacturing or redesign, and increased customer satisfaction. Many companies in healthcare delivery are working to improve environmental
Applying environmental product design to biomedical products research.
Messelbeck, J; Sutherland, L
2000-01-01
The principal themes for the Biomedical Research and the Environment Conference Committee on Environmental Economics in Biomedical Research include the following: healthcare delivery companies and biomedical research organizations, both nonprofit and for-profit, need to improve their environmental performance; suppliers of healthcare products will be called upon to support this need; and improving the environmental profile of healthcare products begins in research and development (R&D). The committee report begins with requirements from regulatory authorities (e.g., U.S. Environmental Protection Agency [EPA], the U.S. Food and Drug Administration), and the healthcare delivery sector). The 1998 American Hospital Association and EPA Memorandum of Understanding to reduce solid waste and mercury from healthcare facilities is emblematic of these requirements. The dominant message from the requirements discussion is to ensure that R&D organizations do not ignore customer, environmental, and regulatory requirements in the early stages of product development. Several representatives from healthcare products manufacturers presented their companies' approaches to meeting these requirements. They reported on efforts to ensure that their R&D processes are sensitive to the environmental consequences from manufacturing, distributing, using, and disposing of healthcare products. These reports describe representatives' awareness of requirements and the unique approaches their R&D organizations have taken to meet these requirements. All representatives reported that their R&D organizations have embraced environmental product design because it avoids the potential of returning products to R&D to improve the environmental profile. Additionally, several reports detailed cost savings, sustainability benefits, and improvements in environmental manufacturing or redesign, and increased customer satisfaction. Many companies in healthcare delivery are working to improve environmental
Smith, Holly C.; Pollock, Ken; Waples, Kelly; Bradley, Stuart; Bejder, Lars
2013-01-01
As delphinid populations become increasingly exposed to human activities we rely on our capacity to produce accurate abundance estimates upon which to base management decisions. This study applied mark–recapture methods following the Robust Design to estimate abundance, demographic parameters, and temporary emigration rates of an Indo-Pacific bottlenose dolphin (Tursiops aduncus) population off Bunbury, Western Australia. Boat-based photo-identification surveys were conducted year-round over three consecutive years along pre-determined transect lines to create a consistent sampling effort throughout the study period and area. The best fitting capture–recapture model showed a population with a seasonal Markovian temporary emigration with time varying survival and capture probabilities. Abundance estimates were seasonally dependent with consistently lower numbers obtained during winter and higher during summer and autumn across the three-year study period. Specifically, abundance estimates for all adults and juveniles (combined) varied from a low of 63 (95% CI 59 to 73) in winter of 2007 to a high of 139 (95% CI 134 to148) in autumn of 2009. Temporary emigration rates (γ') for animals absent in the previous period ranged from 0.34 to 0.97 (mean = 0.54; ±SE 0.11) with a peak during spring. Temporary emigration rates for animals present during the previous period (γ'') were lower, ranging from 0.00 to 0.29, with a mean of 0.16 (± SE 0.04). This model yielded a mean apparent survival estimate for juveniles and adults (combined) of 0.95 (± SE 0.02) and a capture probability from 0.07 to 0.51 with a mean of 0.30 (± SE 0.04). This study demonstrates the importance of incorporating temporary emigration to accurately estimate abundance of coastal delphinids. Temporary emigration rates were high in this study, despite the large area surveyed, indicating the challenges of sampling highly mobile animals which range over large spatial areas. PMID:24130781
Smith, Holly C; Pollock, Ken; Waples, Kelly; Bradley, Stuart; Bejder, Lars
2013-01-01
As delphinid populations become increasingly exposed to human activities we rely on our capacity to produce accurate abundance estimates upon which to base management decisions. This study applied mark-recapture methods following the Robust Design to estimate abundance, demographic parameters, and temporary emigration rates of an Indo-Pacific bottlenose dolphin (Tursiops aduncus) population off Bunbury, Western Australia. Boat-based photo-identification surveys were conducted year-round over three consecutive years along pre-determined transect lines to create a consistent sampling effort throughout the study period and area. The best fitting capture-recapture model showed a population with a seasonal Markovian temporary emigration with time varying survival and capture probabilities. Abundance estimates were seasonally dependent with consistently lower numbers obtained during winter and higher during summer and autumn across the three-year study period. Specifically, abundance estimates for all adults and juveniles (combined) varied from a low of 63 (95% CI 59 to 73) in winter of 2007 to a high of 139 (95% CI 134 to148) in autumn of 2009. Temporary emigration rates (γ') for animals absent in the previous period ranged from 0.34 to 0.97 (mean = 0.54; ±SE 0.11) with a peak during spring. Temporary emigration rates for animals present during the previous period (γ'') were lower, ranging from 0.00 to 0.29, with a mean of 0.16 (± SE 0.04). This model yielded a mean apparent survival estimate for juveniles and adults (combined) of 0.95 (± SE 0.02) and a capture probability from 0.07 to 0.51 with a mean of 0.30 (± SE 0.04). This study demonstrates the importance of incorporating temporary emigration to accurately estimate abundance of coastal delphinids. Temporary emigration rates were high in this study, despite the large area surveyed, indicating the challenges of sampling highly mobile animals which range over large spatial areas. PMID:24130781
Labyrinth Seal Flutter Analysis and Test Validation in Support of Robust Rocket Engine Design
NASA Technical Reports Server (NTRS)
El-Aini, Yehia; Park, John; Frady, Greg; Nesman, Tom
2010-01-01
High energy-density turbomachines, like the SSME turbopumps, utilize labyrinth seals, also referred to as knife-edge seals, to control leakage flow. The pressure drop for such seals is order of magnitude higher than comparable jet engine seals. This is aggravated by the requirement of tight clearances resulting in possible unfavorable fluid-structure interaction of the seal system (seal flutter). To demonstrate these characteristics, a benchmark case of a High Pressure Oxygen Turbopump (HPOTP) outlet Labyrinth seal was studied in detail. First, an analytical assessment of the seal stability was conducted using a Pratt & Whitney legacy seal flutter code. Sensitivity parameters including pressure drop, rotor-to-stator running clearances and cavity volumes were examined and modeling strategies established. Second, a concurrent experimental investigation was undertaken to validate the stability of the seal at the equivalent operating conditions of the pump. Actual pump hardware was used to construct the test rig, also referred to as the (Flutter Rig). The flutter rig did not include rotational effects or temperature. However, the use of Hydrogen gas at high inlet pressure provided good representation of the critical parameters affecting flutter especially the speed of sound. The flutter code predictions showed consistent trends in good agreement with the experimental data. The rig test program produced a stability threshold empirical parameter that separated operation with and without flutter. This empirical parameter was used to establish the seal build clearances to avoid flutter while providing the required cooling flow metering. The calibrated flutter code along with the empirical flutter parameter was used to redesign the baseline seal resulting in a flutter-free robust configuration. Provisions for incorporation of mechanical damping devices were introduced in the redesigned seal to ensure added robustness
NASA Astrophysics Data System (ADS)
Jung, Hoeguk; Wang, Haifeng; Hu, Tingshu
2014-12-01
This paper considers some control design problems in a power system driven by battery/supercapacitor hybrid energy storage devices. The currents in the battery and the supercapacitor are actively controlled by two bidirectional buck-boost converters. Two control objectives are addressed in this paper: one is to achieve robust tracking of two reference variables, the battery current and the load voltage, the other is to achieve smooth transition of these variables during load switch. Based on the state-space averaged model we newly developed, the control design problems are converted into numerically efficient optimization problems with linear matrix inequality (LMI) constraints. An experimental system is constructed to validate the control design methods.
Applying Universal Instructional Design to Course Websites by Using Course Evaluations
ERIC Educational Resources Information Center
Carter, Irene; Leslie, Donald; Kwan, Denise
2012-01-01
The authors explore their use of learner-centred teaching strategies and Universal Instructional Design (UID) on course websites. UID is based on universal design, the design of products and environments intended to be usable by all people to the greatest extent possible (Burgstahler & Cory, 2008). UID applies universal design to instructional…
NASA Astrophysics Data System (ADS)
Layton, Jeffrey B.
1997-06-01
The goal of this paper is to examine the use of covariance control to directly design reduced-order multi-objective controllers for gust alleviation using adaptive materials as the control effector. It will use piezoelectric actuators as control effectors in a finite element model of a full-size wing model. More precisely, the finite element model is of the F-16 Agile Falcon/Active Flexible Wing that is modified to use piezoelectric actuators as control effectors. The paper will also examine the interacting roles of important control design constraints and objectives for designing an aeroservoelastic system. The paper will also present some results of multiobjective control design for the model, illustrating the benefits and complexity of modern practical control design for aeroservoelastic systems that use adaptive materials for actuation.
Robust micromagnet design for fast electrical manipulations of single spins in quantum dots
NASA Astrophysics Data System (ADS)
Yoneda, Jun; Otsuka, Tomohiro; Takakura, Tatsuki; Pioro-Ladrière, Michel; Brunner, Roland; Lu, Hong; Nakajima, Takashi; Obata, Toshiaki; Noiri, Akito; Palmstrøm, Christopher J.; Gossard, Arthur C.; Tarucha, Seigo
2015-08-01
Tailoring spin coupling to electric fields is central to spintronics and spin-based quantum information processing. We present an optimal micromagnet design that produces appropriate stray magnetic fields to mediate fast electrical spin manipulations in nanodevices. We quantify the practical requirements for spatial field inhomogeneity and tolerance for misalignment with spins, and propose a design scheme to improve the spin-rotation frequency (to exceed 50 MHz in GaAs nanostructures). We then validate our design by experiments in separate devices. Our results will open a route to rapidly control solid-state electron spins with limited lifetimes and to study coherent spin dynamics in solids.
Designing a robust activity recognition framework for health and exergaming using wearable sensors.
Alshurafa, Nabil; Xu, Wenyao; Liu, Jason J; Huang, Ming-Chun; Mortazavi, Bobak; Roberts, Christian K; Sarrafzadeh, Majid
2014-09-01
Detecting human activity independent of intensity is essential in many applications, primarily in calculating metabolic equivalent rates and extracting human context awareness. Many classifiers that train on an activity at a subset of intensity levels fail to recognize the same activity at other intensity levels. This demonstrates weakness in the underlying classification method. Training a classifier for an activity at every intensity level is also not practical. In this paper, we tackle a novel intensity-independent activity recognition problem where the class labels exhibit large variability, the data are of high dimensionality, and clustering algorithms are necessary. We propose a new robust stochastic approximation framework for enhanced classification of such data. Experiments are reported using two clustering techniques, K-Means and Gaussian Mixture Models. The stochastic approximation algorithm consistently outperforms other well-known classification schemes which validate the use of our proposed clustered data representation. We verify the motivation of our framework in two applications that benefit from intensity-independent activity recognition. The first application shows how our framework can be used to enhance energy expenditure calculations. The second application is a novel exergaming environment aimed at using games to reward physical activity performed throughout the day, to encourage a healthy lifestyle. PMID:24235280
Design of a robust multivariable proportional plus integral controller via spectral assignment
NASA Technical Reports Server (NTRS)
Mielke, R. R.; Maynard, R. A.; Liberty, S. R.
1980-01-01
A new design procedure for a class of multivariable integral plus proportional servo control systems is presented. The procedure utilizes a null space formulation of the eigensystem assignment problem assuming complete state feedback. Reduced order observers are used to estimate unavailable states. The resulting system realizes arbitrary closed-loop eigenvalues, approximates specified modal behavior and achieves low eigensystem sensitivity with respect to plant parameter variations. A tutorial example to illustrate the design procedure is included.
Hasanvand, Hamed; Mozafari, Babak; Arvan, Mohammad R; Amraee, Turaj
2015-11-01
This paper addresses the application of a static Var compensator (SVC) to improve the damping of interarea oscillations. Optimal location and size of SVC are defined using bifurcation and modal analysis to satisfy its primary application. Furthermore, the best-input signal for damping controller is selected using Hankel singular values and right half plane-zeros. The proposed approach is aimed to design a robust PI controller based on interval plants and Kharitonov's theorem. The objective here is to determine the stability region to attain robust stability, the desired phase margin, gain margin, and bandwidth. The intersection of the resulting stability regions yields the set of kp-ki parameters. In addition, optimal multiobjective design of PI controller using particle swarm optimization (PSO) algorithm is presented. The effectiveness of the suggested controllers in damping of local and interarea oscillation modes of a multimachine power system, over a wide range of loading conditions and system configurations, is confirmed through eigenvalue analysis and nonlinear time domain simulation. PMID:26410448
Huang, Dong; Cabral, Ricardo; De la Torre, Fernando
2016-02-01
Discriminative methods (e.g., kernel regression, SVM) have been extensively used to solve problems such as object recognition, image alignment and pose estimation from images. These methods typically map image features ( X) to continuous (e.g., pose) or discrete (e.g., object category) values. A major drawback of existing discriminative methods is that samples are directly projected onto a subspace and hence fail to account for outliers common in realistic training sets due to occlusion, specular reflections or noise. It is important to notice that existing discriminative approaches assume the input variables X to be noise free. Thus, discriminative methods experience significant performance degradation when gross outliers are present. Despite its obvious importance, the problem of robust discriminative learning has been relatively unexplored in computer vision. This paper develops the theory of robust regression (RR) and presents an effective convex approach that uses recent advances on rank minimization. The framework applies to a variety of problems in computer vision including robust linear discriminant analysis, regression with missing data, and multi-label classification. Several synthetic and real examples with applications to head pose estimation from images, image and video classification and facial attribute classification with missing data are used to illustrate the benefits of RR. PMID:26761740
Meyer-Baese, A; Theis, F; Emmett, M R
2010-01-01
The tryptophan system present in Escherichia coli represents an important regulatory unit described by multiple feedback loops. The role of these feedback loops is crucial for the analysis of the dynamical behavior of the tryptophan synthesis. We analyze the robust stability of this system which models the dynamics of both fast state, such as transcription and synthesis of free operator, and slow state, such as translation and tryptophan synthesis under consideration of nonlinear uncertainties. In addition, we analyze the role of these feedback loops as key design components of this regulatory unit responsible for its physiological performance. The range of allowed parameter perturbations and the conditions that ensure the existence of asymptotically stable equilibria of the perturbed system are determined. We also analyze two important alternate regulatory designs for the tryptophan synthesis pathway and derive the stability conditions. PMID:20865501
Oliveira, Luciana F; Braga, Soraia C G N; Filgueiras, Paulo R; Augusto, Fabio; Poppi, Ronei J
2014-11-01
Plackett-Burman experimental design was applied for the robustness assessment of GC×GC-qMS (Comprehensive Two-Dimensional Gas Chromatography with Fast Quadrupolar Mass Spectrometric Detection) in quantitative and qualitative analysis of volatiles compounds from chocolate samples isolated by headspace solid-phase microextraction (HS-SPME). The influence of small changes around the nominal level of six factors deemed as important on peak areas (carrier gas flow rate, modulation period, temperature of ionic source, MS photomultiplier power, injector temperature and interface temperature) and of four factors considered as potentially influential on spectral quality (minimum and maximum limits of the scanned mass ranges, ions source temperature and photomultiplier power). The analytes selected for the study were 2,3,5-trimethylpyrazine, 2-octanone, octanal, 2-pentyl-furan, 2,3,5,6-tetramethylpyrazine, and 2-nonanone e nonanal. The factors pointed out as important on the robustness of the system were photomultiplier power for quantitative analysis and lower limit of mass scanning range for qualitative analysis. PMID:25127599
Robust control for uncertain structures
NASA Technical Reports Server (NTRS)
Douglas, Joel; Athans, Michael
1991-01-01
Viewgraphs on robust control for uncertain structures are presented. Topics covered include: robust linear quadratic regulator (RLQR) formulas; mismatched LQR design; RLQR design; interpretations of RLQR design; disturbance rejection; and performance comparisons: RLQR vs. mismatched LQR.
An application of robust parameter design using an alternative to Taguchi methods
Abate, M.L.; Morrow, M.C.; Kuczek, T.
1996-11-01
The factors of interest in designing a product or process can generally be classified into two categories, controllable and uncontrollable. Controllable (or control) factors represent those factors which can be regulated. Examples of control factors include: the choice of material, flow rates, processing pressures, times and temperatures. Uncontrollable (noise) factors are those that are either difficult, impossible or too expensive to control during actual production or use. Examples of noise factors are: environmental conditions such as ambient temperature or humidity, process parameters which are dictated by an outside source such as end user demand, and usage factors such as how long and at what temperature a consumer stores a product. As compared to the current Tagachi approach, a new design method which provides greater flexibility in the design of the experiment, utilize a more meaningful performance statistic, and lend itself to a better understanding of the product or process is described in this paper.
Advanced Vibration Analysis Tools and New Strategies for Robust Design of Turbine Engine Rotors
NASA Technical Reports Server (NTRS)
Min, James B.
2002-01-01
The adverse effects of small, random structural irregularities among the blades, called mistuning, can result in blade forced-response amplitudes and stresses that are much larger than those predicted for a perfectly tuned rotor. Manufacturing tolerances, deviations in material properties, or nonuniform operational wear causes mistuning; therefore, mistuning is unavoidable. Furthermore, even a small mistuning can have a dramatic effect on the vibratory behavior of a rotor because it can lead to spatial localization of the vibration energy (see the following photographs). As a result, certain blades may experience forced response amplitudes and stresses that are substantially larger than those predicted by an analysis of the nominal (tuned) design. Unfortunately, these random uncertainties in blade properties, and the immense computational effort involved in obtaining statistically reliable design data, combine to make this aspect of rotor design cumbersome.
Haan, S W; Herrmann, M C; Dittrich, T R; Fetterman, A J; Marinak, M M; Munro, D; Pollaine, S M; Salmonson, J D; Strobel, G L; Suter, L J
2004-11-12
Target designs are described that are meant to achieve ignition on the National Ignition Facility. Simulations of recent indirect drive cryogenic capsule designs indicate dramatically reduced growth of short wavelength hydrodynamic instabilities, resulting from two changes in the designs. First, better optimization results from systematic mapping of the ignition target performance over the parameter space of ablator and DT-ice thickness combinations, using techniques developed by one of us (Herrmann). After the space is mapped with one-dimensional simulations, exploration of it with two-dimensional simulations quantifies the dependence of instability growth on target dimensions. Low modes and high modes grow differently in different regions of the space, allowing a trade-off of the two regimes of growth. Significant improvement in high-mode stability can be achieved, relative to previous designs, with only insignificant increase in low-mode growth. This procedure produces capsule designs that, in simulations, tolerate several times the surface roughness that could be tolerated by capsules optimized by older more heuristic techniques. Another significant reduction in instability growth, by another factor of several, is achieved with ablators with 'graded dopants.' In this type of capsule the mid-Z dopant, which is needed in the ablator to minimize x-ray preheat at the ablator-ice interface, is optimally positioned within the ablator. A fabrication scenario for graded dopants already exists, using sputter coating to fabricate the ablator shell. We describe the systematics of these advances in capsule design, discuss the basis behind their improved performance, and summarize how this is affecting our plans for NIF ignition.
Flat-top MZI filters: a novel robust design based on MMI splitters
NASA Astrophysics Data System (ADS)
Cherchi, Matteo; Harjanne, Mikko; Ylinen, Sami; Kapulainen, Markku; Vehmas, Tapani; Aalto, Timo
2016-03-01
Multimode Interferometers (MMIs) are an attractive alternative to directional couplers, ensuring more relaxed tolerances to fabrication errors and broader operation bandwidth. The drawback is that only a limited discrete set of splitting ratios is achievable with MMIs of constant cross section. This issue clearly limits their use in flat-top interferometric filters, which design requires, in general, free choice of the splitting ratios. Here we show for the first time that it is possible to design 4-stage flat-top interferometers using only standard MMIs with 50:50 and 85:15 splitting ratios. The design approach is based on the representation of the system on the Bloch sphere. Flat-top interleavers with different free spectral ranges have been designed and fabricated on the silicon photonics platform of VTT, based on 3 μm thick rib and strip waveguides. Two different layouts have been explored: one where all components are collinear and a more compact one which elements have been folded in a spiral shape. All interleavers have been designed for TE polarization, and they work in a wavelength range comparable with the 100 nm bandwidth of the MMI splitters. Even though fabrication imperfections and non-ideal behaviour of both waveguide bends and MMIs led to reduced extinction compared to simulations, most devices show in-band extinction exceeding 15 dB. The in-band losses of the most central channels did not exceed 1.5 dB compared to the reference straight waveguide. The designed interleavers can be employed in cascaded configurations to achieve broadband and fabrication tolerant flat-top wavelength (de)multiplexers.
Estimation of recruitment from immigration versus in situ reproduction using Pollock's robust design
Nichols, J.D.; Pollock, K.H.
1990-01-01
Recruitment to animal populations can occur through both immigration and in situ reproduction. These two components of recruitment are conceptually distinct and lead to different mechanistic models of population dynamics. We describe a capture-recapture design that can be used to obtain separate estimates of these two recruitment components
ERIC Educational Resources Information Center
He, Yong
2013-01-01
Common test items play an important role in equating multiple test forms under the common-item nonequivalent groups design. Inconsistent item parameter estimates among common items can lead to large bias in equated scores for IRT true score equating. Current methods extensively focus on detection and elimination of outlying common items, which…
Applying Semiotic Theories to Graphic Design Education: An Empirical Study on Poster Design Teaching
ERIC Educational Resources Information Center
Yang, Chao-Ming; Hsu, Tzu-Fan
2015-01-01
The rationales behind design are dissimilar to those behind art. Establishing an adequate theoretical foundation for conducting design education can facilitate scientising design methods. Thus, from the perspectives of the semiotic theories proposed by Saussure and Peirce, we investigated graphic design curricula by performing teaching…
13 CFR 108.300 - When and how to apply for designation as a NMVC Company.
Code of Federal Regulations, 2010 CFR
2010-01-01
... designation as a NMVC Company. 108.300 Section 108.300 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION NEW MARKETS VENTURE CAPITAL (âNMVCâ) PROGRAM Application and Approval Process for NMVC Company Designation § 108.300 When and how to apply for designation as a NMVC Company. (a) Notice of...
NASA Astrophysics Data System (ADS)
Azizi, Seyed Naser; Asemi, Neda; Samadi-Maybodi, Abdolrouf
2012-09-01
In this study, perlite was used as a low-cost source of Si and Al to synthesis of nanocrystalline cancrinite zeolite. The synthesis of cancrinite zeolite from perlite by using the alkaline hydrothermal treatment under saturated steam pressure was investigated. A statistical Taguchi design of experiments was employed to evaluate the effects of the process variables such as type of aging, aging time and hydrothermal crystallization time on the crystallnity of synthesized zeolite. The optimum conditions for maximum crystallinity of nanocrystalline cancrinite were obtained as microwave-assisted aging, 60 min aging time and 6 h hydrothermal crystallization time from statistical analysis of the experimental results using Taguchi design. The synthetic samples were characterization by XRD, FT-IR and FE-SEM techniques. The results showed that the microwave-assisted aging can shorten the crystallization time and reduced the crystal size to form nanocrystalline cancrinite zeolite.
Thermochemical hydrolysis of macroalgae Ulva for biorefinery: Taguchi robust design method
Jiang, Rui; Linzon, Yoav; Vitkin, Edward; Yakhini, Zohar; Chudnovsky, Alexandra; Golberg, Alexander
2016-01-01
Understanding the impact of all process parameters on the efficiency of biomass hydrolysis and on the final yield of products is critical to biorefinery design. Using Taguchi orthogonal arrays experimental design and Partial Least Square Regression, we investigated the impact of change and the comparative significance of thermochemical process temperature, treatment time, %Acid and %Solid load on carbohydrates release from green macroalgae from Ulva genus, a promising biorefinery feedstock. The average density of hydrolysate was determined using a new microelectromechanical optical resonator mass sensor. In addition, using Flux Balance Analysis techniques, we compared the potential fermentation yields of these hydrolysate products using metabolic models of Escherichia coli, Saccharomyces cerevisiae wild type, Saccharomyces cerevisiae RN1016 with xylose isomerase and Clostridium acetobutylicum. We found that %Acid plays the most significant role and treatment time the least significant role in affecting the monosaccharaides released from Ulva biomass. We also found that within the tested range of parameters, hydrolysis with 121 °C, 30 min 2% Acid, 15% Solids could lead to the highest yields of conversion: 54.134–57.500 gr ethanol kg−1 Ulva dry weight by S. cerevisiae RN1016 with xylose isomerase. Our results support optimized marine algae utilization process design and will enable smart energy harvesting by thermochemical hydrolysis. PMID:27291594
Thermochemical hydrolysis of macroalgae Ulva for biorefinery: Taguchi robust design method.
Jiang, Rui; Linzon, Yoav; Vitkin, Edward; Yakhini, Zohar; Chudnovsky, Alexandra; Golberg, Alexander
2016-01-01
Understanding the impact of all process parameters on the efficiency of biomass hydrolysis and on the final yield of products is critical to biorefinery design. Using Taguchi orthogonal arrays experimental design and Partial Least Square Regression, we investigated the impact of change and the comparative significance of thermochemical process temperature, treatment time, %Acid and %Solid load on carbohydrates release from green macroalgae from Ulva genus, a promising biorefinery feedstock. The average density of hydrolysate was determined using a new microelectromechanical optical resonator mass sensor. In addition, using Flux Balance Analysis techniques, we compared the potential fermentation yields of these hydrolysate products using metabolic models of Escherichia coli, Saccharomyces cerevisiae wild type, Saccharomyces cerevisiae RN1016 with xylose isomerase and Clostridium acetobutylicum. We found that %Acid plays the most significant role and treatment time the least significant role in affecting the monosaccharaides released from Ulva biomass. We also found that within the tested range of parameters, hydrolysis with 121 °C, 30 min 2% Acid, 15% Solids could lead to the highest yields of conversion: 54.134-57.500 gr ethanol kg(-1) Ulva dry weight by S. cerevisiae RN1016 with xylose isomerase. Our results support optimized marine algae utilization process design and will enable smart energy harvesting by thermochemical hydrolysis. PMID:27291594
Design of robust state feedback controllers via eigenvalue/eigenvector assignment
NASA Technical Reports Server (NTRS)
Mielke, R. R.; Maynard, R. A.; Liberty, S. R.; Srinathkumar, S.
1979-01-01
A new method of selecting a multivariable state feedback controller is presented. The resulting controller simultaneously realizes arbitrary closed-loop eigenvalues, approximates specified modal behavior and achieves low eigensystem sensitivity with respect to plant parameter variations. The method characterizes a vector space slightly larger than the null space of the closed-loop system matrix and projects a desired modal matrix onto this space. Sensitivity of eigenvalues and eigenvectors is then minimized local to the desired modal matrix using a gradient search technique. A tutorial example to illustrate the design procedure is given.
Promoting Robust Design of Diode Lasers for Space: A National Initiative
NASA Technical Reports Server (NTRS)
Tratt, David M.; Amzajerdian, Farzin; Kashem, Nasir B.; Shapiro, Andrew A.; Mense, Allan T.
2007-01-01
The Diode-laser Array Working Group (DAWG) is a national-level consumer/provider forum for discussion of engineering and manufacturing issues which influence the reliability and survivability of high-power broad-area laser diode devices in space, with an emphasis on laser diode arrays (LDAs) for optical pumping of solid-state laser media. The goals of the group are to formulate and validate standardized test and qualification protocols, operational control recommendations, and consensus manufacturing and certification standards. The group is using reliability and lifetime data collected by laser diode manufacturers and the user community to develop a set of standardized guidelines for specifying and qualifying laser diodes for long-duration operation in space, the ultimate goal being to promote an informed U.S. Government investment and procurement strategy for assuring the availability and durability of space-qualified LDAs. The group is also working to establish effective implementation of statistical design techniques at the supplier design, development, and manufacturing levels to help reduce product performance variability and improve product reliability for diodes employed in space applications
Wireless sensing and vibration control with increased redundancy and robustness design.
Li, Peng; Li, Luyu; Song, Gangbing; Yu, Yan
2014-11-01
Control systems with long distance sensor and actuator wiring have the problem of high system cost and increased sensor noise. Wireless sensor network (WSN)-based control systems are an alternative solution involving lower setup and maintenance costs and reduced sensor noise. However, WSN-based control systems also encounter problems such as possible data loss, irregular sampling periods (due to the uncertainty of the wireless channel), and the possibility of sensor breakdown (due to the increased complexity of the overall control system). In this paper, a wireless microcontroller-based control system is designed and implemented to wirelessly perform vibration control. The wireless microcontroller-based system is quite different from regular control systems due to its limited speed and computational power. Hardware, software, and control algorithm design are described in detail to demonstrate this prototype. Model and system state compensation is used in the wireless control system to solve the problems of data loss and sensor breakdown. A positive position feedback controller is used as the control law for the task of active vibration suppression. Both wired and wireless controllers are implemented. The results show that the WSN-based control system can be successfully used to suppress the vibration and produces resilient results in the presence of sensor failure. PMID:25330471
Macromodeling for analog design and robustness boosting in bio-inspired computing models
NASA Astrophysics Data System (ADS)
Cuadri, J.; Linan, G.; Roca, E.; Rodriguez-Vazquez, A.
2005-06-01
Setting specifications for the electronic implementation of biological neural-network-like vision systems on-chip is not straightforward, neither it is to simulate the resulting circuit. The structure of these systems leads to a netlist of more than 100.000 nodes for a small array of 100x150 pixels. Moreover, introducing an optical input in the low level simulation is nowadays not feasible with standard electrical simulation environments. Given that, to accomplish the task of integrating those systems in silicon to build compact, low power consuming, and reliable systems, a previous step in the standard analog electronic design flux should be introduced. Here a methodology to make the translation from the biological model to circuit-level specifications for electronic design is proposed. The purpose is to include non ideal effects as mismatching, noise, leakages, supply degradation, feedthrough, and temperature of operation in a high level description of the implementation, in order to accomplish behavioural simulations that require less computational effort and resources. A particular case study is presented, the analog electronic implementation of the locust"s Lobula Giant Movement Detector (LGMD), a neural structure that fires a collision alarm based on visual information. The final goal is a collision threat detection vision system on-chip for automotive applications.
Wu, Zhen-Yu; Liang, Hai-Wei; Chen, Li-Feng; Hu, Bi-Cheng; Yu, Shu-Hong
2016-01-19
Three dimensional (3D) carbon nanomaterials exhibit great application potential in environmental protection, electrochemical energy storage and conversion, catalysis, polymer science, and advanced sensors fields. Current methods for preparing 3D carbon nanomaterials, for example, carbonization of organogels, chemical vapor deposition, and self-assembly of nanocarbon building blocks, inevitably involve some drawbacks, such as expensive and toxic precursors, complex equipment and technological requirements, and low production ability. From the viewpoint of practical application, it is highly desirable to develop a simple, cheap, and environmentally friendly way for fabricating 3D carbon nanomaterials in large scale. On the other hand, in order to extend the application scope and improve the performance of 3D carbon nanomaterials, we should explore efficient strategies to prepare diverse functional nanomaterials based on their 3D carbon structure. Recently, many researchers tend to fabricate high-performance 3D carbon-based nanomaterials from biomass, which is low cost, easy to obtain, and nontoxic to humans. Bacterial cellulose (BC), a typical biomass material, has long been used as the raw material of nata-de-coco (an indigenous dessert food of the Philippines). It consists of a polysaccharide with a β-1,4-glycosidic linkage and has a interconnected 3D porous network structure. Interestingly, the network is made up of a random assembly of cellulose nanofibers, which have a high aspect ratio with a diameter of 20-100 nm. As a result, BC has a high specific surface area. Additionally, BC hydrogels can be produced on an industrial scale via a microbial fermentation process at a very low price. Thus, it can be an ideal platform for design of 3D carbon-based functional nanomaterials. Before our work, no systematic work and summary on this topic had been reported. This Account presents the concepts and strategies of our studies on BC in the past few years, that is
Design of a robust modulation controller over a wide range of load characteristics for ac/dc systems
Choudry, M.A.; Reza, M.A. . Dept. of Electrical Engineering); Ellithy, K.A. )
1990-02-01
This paper presents a method to design a robust modulation controller to improve the dynamic performance of ac/dc systems. Static load is modeled as a nonlinear function of load bus voltage and dynamic load is modeled by an equivalent induction motor. Reactive power and dc power are considered for the modulation control. Static var compensator (SVC) is used for the reactive power modulation. The rotor speed and angle deviations of the synchronous generator are used as a stabilizing signal to the SVC. The controller gains are selected based on the eigenvalue sensitivity of electromechanical mode of the closed loop system with respect to load characteristic. Eigenvalue analysis and simulation results show that the proposed reactive power modulation control improves the system response over a wide range of voltage dependent load characteristic as compared with the control using only the rotor speed deviation.
Estimating parameters of hidden Markov models based on marked individuals: use of robust design data
Kendall, William L.; White, Gary C.; Hines, James E.; Langtimm, Catherine A.; Yoshizaki, Jun
2012-01-01
Development and use of multistate mark-recapture models, which provide estimates of parameters of Markov processes in the face of imperfect detection, have become common over the last twenty years. Recently, estimating parameters of hidden Markov models, where the state of an individual can be uncertain even when it is detected, has received attention. Previous work has shown that ignoring state uncertainty biases estimates of survival and state transition probabilities, thereby reducing the power to detect effects. Efforts to adjust for state uncertainty have included special cases and a general framework for a single sample per period of interest. We provide a flexible framework for adjusting for state uncertainty in multistate models, while utilizing multiple sampling occasions per period of interest to increase precision and remove parameter redundancy. These models also produce direct estimates of state structure for each primary period, even for the case where there is just one sampling occasion. We apply our model to expected value data, and to data from a study of Florida manatees, to provide examples of the improvement in precision due to secondary capture occasions. We also provide user-friendly software to implement these models. This general framework could also be used by practitioners to consider constrained models of particular interest, or model the relationship between within-primary period parameters (e.g., state structure) and between-primary period parameters (e.g., state transition probabilities).
Kendall, William L; White, Gary C; Hines, James E; Langtimm, Catherine A; Yoshizaki, Jun
2012-04-01
Development and use of multistate mark-recapture models, which provide estimates of parameters of Markov processes in the face of imperfect detection, have become common over the last 20 years. Recently, estimating parameters of hidden Markov models, where the state of an individual can be uncertain even when it is detected, has received attention. Previous work has shown that ignoring state uncertainty biases estimates of survival and state transition probabilities, thereby reducing the power to detect effects. Efforts to adjust for state uncertainty have included special cases and a general framework for a single sample per period of interest. We provide a flexible framework for adjusting for state uncertainty in multistate models, while utilizing multiple sampling occasions per period of interest to increase precision and remove parameter redundancy. These models also produce direct estimates of state structure for each primary period, even for the case where there is just one sampling occasion. We apply our model to expected-value data, and to data from a study of Florida manatees, to provide examples of the improvement in precision due to secondary capture occasions. We have also implemented these models in program MARK. This general framework could also be used by practitioners to consider constrained models of particular interest, or to model the relationship between within-primary-period parameters (e.g., state structure) and between-primary-period parameters (e.g., state transition probabilities). PMID:22690641
Mechanisms for Robust Cognition.
Walsh, Matthew M; Gluck, Kevin A
2015-08-01
To function well in an unpredictable environment using unreliable components, a system must have a high degree of robustness. Robustness is fundamental to biological systems and is an objective in the design of engineered systems such as airplane engines and buildings. Cognitive systems, like biological and engineered systems, exist within variable environments. This raises the question, how do cognitive systems achieve similarly high degrees of robustness? The aim of this study was to identify a set of mechanisms that enhance robustness in cognitive systems. We identify three mechanisms that enhance robustness in biological and engineered systems: system control, redundancy, and adaptability. After surveying the psychological literature for evidence of these mechanisms, we provide simulations illustrating how each contributes to robust cognition in a different psychological domain: psychomotor vigilance, semantic memory, and strategy selection. These simulations highlight features of a mathematical approach for quantifying robustness, and they provide concrete examples of mechanisms for robust cognition. PMID:25352094
Trabelsi, O; Villalobos, J L López; Ginel, A; Cortes, E Barrot; Doblaré, M
2014-05-01
Swallowing depends on physiological variables that have a decisive influence on the swallowing capacity and on the tracheal stress distribution. Prosthetic implantation modifies these values and the overall performance of the trachea. The objective of this work was to develop a decision support system based on experimental, numerical and statistical approaches, with clinical verification, to help the thoracic surgeon in deciding the position and appropriate dimensions of a Dumon prosthesis for a specific patient in an optimal time and with sufficient robustness. A code for mesh adaptation to any tracheal geometry was implemented and used to develop a robust experimental design, based on the Taguchi's method and the analysis of variance. This design was able to establish the main swallowing influencing factors. The equations to fit the stress and the vertical displacement distributions were obtained. The resulting fitted values were compared to those calculated directly by the finite element method (FEM). Finally, a checking and clinical validation of the statistical study were made, by studying two cases of real patients. The vertical displacements and principal stress distribution obtained for the specific tracheal model were in agreement with those calculated by FE simulations with a maximum absolute error of 1.2 mm and 0.17 MPa, respectively. It was concluded that the resulting decision support tool provides a fast, accurate and simple tool for the thoracic surgeon to predict the stress state of the trachea and the reduction in the ability to swallow after implantation. Thus, it will help them in taking decisions during pre-operative planning of tracheal interventions. PMID:23046526
A.G. Ware; D.K. Morton; N.L. Smith; S.D. Snow; T.E. Rahl
1999-08-01
The Department of Energy (DOE) has developed a design concept for a set of standard canisters for the handling, interim storage, transportation, and disposal in the national repository, of DOE spent nuclear fuel (SNF). The standardized DOE SNF canister has to be capable of handling virtually all of the DOE SNF in a variety of potential storage and transportation systems. It must also be acceptable to the repository, based on current and anticipated future requirements. This expected usage mandates a robust design. The canister design has four unique geometries, with lengths of approximately 10 feet or 15 feet, and an outside nominal diameter of 18 inches or 24 inches. The canister has been developed to withstand a drop from 30 feet onto a rigid (flat) surface, sustaining only minor damage - but no rupture - to the pressure (containment) boundary. The majority of the end drop-induced damage is confined to the skirt and lifting/stiffening ring components, which can be removed if de sired after an accidental drop. A canister, with its skirt and stiffening ring removed after an accidental drop, can continue to be used in service with appropriate operational steps being taken. Features of the design concept have been proven through drop testing and finite element analyses of smaller test specimens. Finite element analyses also validated the canister design for drops onto a rigid (flat) surface for a variety of canister orientations at impact, from vertical to 45 degrees off vertical. Actual 30-foot drop testing has also been performed to verify the final design, though limited to just two full-scale test canister drops. In each case, the analytical models accurately predicted the canister response.
NASA Astrophysics Data System (ADS)
Bosse, Stefan
2013-05-01
Sensorial materials consisting of high-density, miniaturized, and embedded sensor networks require new robust and reliable data processing and communication approaches. Structural health monitoring is one major field of application for sensorial materials. Each sensor node provides some kind of sensor, electronics, data processing, and communication with a strong focus on microchip-level implementation to meet the goals of miniaturization and low-power energy environments, a prerequisite for autonomous behaviour and operation. Reliability requires robustness of the entire system in the presence of node, link, data processing, and communication failures. Interaction between nodes is required to manage and distribute information. One common interaction model is the mobile agent. An agent approach provides stronger autonomy than a traditional object or remote-procedure-call based approach. Agents can decide for themselves, which actions are performed, and they are capable of flexible behaviour, reacting on the environment and other agents, providing some degree of robustness. Traditionally multi-agent systems are abstract programming models which are implemented in software and executed on program controlled computer architectures. This approach does not well scale to micro-chip level and requires full equipped computers and communication structures, and the hardware architecture does not consider and reflect the requirements for agent processing and interaction. We propose and demonstrate a novel design paradigm for reliable distributed data processing systems and a synthesis methodology and framework for multi-agent systems implementable entirely on microchip-level with resource and power constrained digital logic supporting Agent-On-Chip architectures (AoC). The agent behaviour and mobility is fully integrated on the micro-chip using pipelined communicating processes implemented with finite-state machines and register-transfer logic. The agent behaviour
Park, Chul Soon; Lee, Han Ju; Jamison, Andrew C; Lee, T Randall
2016-07-26
A series of custom-designed alkanethioacetate ligands were synthesized to provide a facile method of attaching maleimide-terminated adsorbates to gold nanostructures via thiolate bonds. Monolayers on flat gold substrates derived from both mono- and dithioacetates, with and without oligo(ethylene glycol) (OEG) moieties in their alkyl spacers, were characterized using X-ray photoelectron spectroscopy, polarization modulation infrared reflection-absorption spectroscopy, ellipsometry, and contact angle goniometry. For all adsorbates, the resulting monolayers revealed that a higher packing density and more homogeneous surface were generated when the film was formed in EtOH, but a higher percentage of bound thiolate was obtained in THF. A series of gold nanoparticles (AuNPs) capped with each adsorbate were prepared to explore how adsorbate structure influences aqueous colloidal stability under extreme conditions, as examined visually and spectroscopically. The AuNPs coated with adsorbates that include OEG moieties exhibited enhanced stability under high salt concentration, and AuNPs capped with dithioacetate adsorbates exhibited improved stability against ligand exchange in competition with dithiothreitol (DTT). Overall, the best results were obtained with a chelating dithioacetate adsorbate that included OEG moieties in its alkyl spacer, imparting improved stability via enhanced solubility in water and superior adsorbate attachment owing to the chelate effect. PMID:27385466
Extreme temperature robust optical sensor designs and fault-tolerant signal processing
Riza, Nabeel Agha; Perez, Frank
2012-01-17
Silicon Carbide (SiC) probe designs for extreme temperature and pressure sensing uses a single crystal SiC optical chip encased in a sintered SiC material probe. The SiC chip may be protected for high temperature only use or exposed for both temperature and pressure sensing. Hybrid signal processing techniques allow fault-tolerant extreme temperature sensing. Wavelength peak-to-peak (or null-to-null) collective spectrum spread measurement to detect wavelength peak/null shift measurement forms a coarse-fine temperature measurement using broadband spectrum monitoring. The SiC probe frontend acts as a stable emissivity Black-body radiator and monitoring the shift in radiation spectrum enables a pyrometer. This application combines all-SiC pyrometry with thick SiC etalon laser interferometry within a free-spectral range to form a coarse-fine temperature measurement sensor. RF notch filtering techniques improve the sensitivity of the temperature measurement where fine spectral shift or spectrum measurements are needed to deduce temperature.
Pavía-Sanders, Adriana; Zhang, Shiyi; Flores, Jeniree A; Sanders, Jonathan E; Raymond, Jeffery E; Wooley, Karen L
2013-09-24
Well-defined, magnetic shell cross-linked knedel-like nanoparticles (MSCKs) with hydrodynamic diameters ca. 70 nm were constructed through the co-assembly of amphiphilic block copolymers of PAA20-b-PS280 and oleic acid-stabilized magnetic iron oxide nanoparticles using tetrahydrofuran, N,N-dimethylformamide, and water, ultimately transitioning to a fully aqueous system. These hybrid nanomaterials were designed for application as sequestering agents for hydrocarbons present in crude oil, based upon their combination of amphiphilic organic domains, for aqueous solution dispersibility and capture of hydrophobic guest molecules, with inorganic core particles for magnetic responsivity. The employment of these MSCKs in a contaminated aqueous environment resulted in the successful removal of the hydrophobic contaminants at a ratio of 10 mg of oil per 1 mg of MSCK. Once loaded, the crude oil-sorbed nanoparticles were easily isolated via the introduction of an external magnetic field. The recovery and reusability of these MSCKs were also investigated. These results suggest that deployment of hybrid nanocomposites, such as these, could aid in environmental remediation efforts, including at oil spill sites, in particular, following the bulk recovery phase. PMID:23987122
NASA Astrophysics Data System (ADS)
Bayer, Peter; de Paly, Michael; Bürger, Claudius M.
2010-05-01
This study demonstrates the high efficiency of the so-called stack-ordering technique for optimizing a groundwater management problem under uncertain conditions. The uncertainty is expressed by multiple equally probable model representations, such as realizations of hydraulic conductivity. During optimization of a well-layout problem for contaminant control, a ranking mechanism is applied that extracts those realizations that appear most critical for the optimization problem. It is shown that this procedure works well for evolutionary optimization algorithms, which are to some extent robust against noisy objective functions. More precisely, differential evolution (DE) and the Covariance Matrix Adaptation Evolution Strategy (CMA-ES) are applied. Stack ordering is comprehensively investigated for a plume management problem at a hypothetical template site based on parameter values measured at and on a geostatistical model developed for the Lauswiesen study site near Tübingen, Germany. The straightforward procedure yields computational savings above 90% in comparison to always evaluating the full set of realizations. This is confirmed by cross testing with four additional validation cases. The results show that both evolutionary algorithms obtain highly reliable near-optimal solutions. DE appears to be the better choice for cases with significant noise caused by small stack sizes. On the other hand, there seems to be a problem-specific threshold for the evaluation stack size above which the CMA-ES achieves solutions with both better fitness and higher reliability.
Practical Findings from Applying the PSD Model for Evaluating Software Design Specifications
NASA Astrophysics Data System (ADS)
Räisänen, Teppo; Lehto, Tuomas; Oinas-Kukkonen, Harri
This paper presents practical findings from applying the PSD model to evaluating the support for persuasive features in software design specifications for a mobile Internet device. On the one hand, our experiences suggest that the PSD model fits relatively well for evaluating design specifications. On the other hand, the model would benefit from more specific heuristics for evaluating each technique to avoid unnecessary subjectivity. Better distinction between the design principles in the social support category would also make the model easier to use. Practitioners who have no theoretical background can apply the PSD model to increase the persuasiveness of the systems they design. The greatest benefit of the PSD model for researchers designing new systems may be achieved when it is applied together with a sound theory, such as the Elaboration Likelihood Model. Using the ELM together with the PSD model, one may increase the chances for attitude change.
ERIC Educational Resources Information Center
Beck, Tanja; Diaz del Castillo, Patricia; Fovet, Frederic; Mole, Heather; Noga, Brodie
2014-01-01
This article presents out an outcome analysis of a Universal Design (UD) audit to the various professional facets of a disability service (DS) provider's office on a large North American campus. The context of the audit is a broad campus-wide drive to implement Universal Design for Learning (UDL) in teaching practices. In an effort for…
Younkin, James R; March-Leuba, Jose A; Garner, James R
2013-01-01
Oak Ridge National Laoratory (ORNL) has engineered an on-line enrichment monitor (OLEM) to continuously measure U-235 emissions from the UF6 gas flowing through a unit header pipe of a gas centrifuge enrichment plant (GCEP) as a component of the International Atomic Energy Agency s (IAEA) new generation of technology to support enrichment plant safeguards1. In contrast to other enrichment monitoring approaches, OLEM calibrates and corrects for the pressure and temperature dependent UF6 gas-density without external radiation sources by using the inherent unit header pipe pressure dynamics and combining U-235 gamma-ray spectrometery using a shielded NaI detector with gas pressure and temperature data near the spectrum measurement point to obtain the enrichment of the gas as a function of time. From a safeguards perspective, OLEM can provide early detection of a GCEP being misused for production of highly enriched uranium, but would not detect directly the isolation and use of a cascade within the production unit to produce HEU. OLEM may also reduce the number of samples collected for destructive assay and, if coupled with load cell monitoring, could support isotope mass balance verification and unattended cylinder verification. The earlier paper presented OLEM as one component along with shared load cells and unattended cylinder verification, in the IAEA emering toolbox for unattended instruments at GCEPs1 and described the OLEM concept and how previous modeling studies and field measurements helped confirm the viability of a passive on-line enrichment monitor for meeting IAEA objectives and to support the development of performance targets. Phase I of the United States Support Program (USSP) OLEM project completed a preliminary hardware, software and communications design; phase II will build and test field prototypes in controlled laboratory settings and then at an operational facility. That paper also discussed many of the OLEM collection node commercial off the
Debrus, Benjamin; Lebrun, Pierre; Ceccato, Attilio; Caliaro, Gabriel; Rozet, Eric; Nistor, Iolanda; Oprean, Radu; Rupérez, Francisco J; Barbas, Coral; Boulanger, Bruno; Hubert, Philippe
2011-04-01
HPLC separations of an unknown sample mixture and a pharmaceutical formulation have been optimized using a recently developed chemometric methodology proposed by W. Dewé et al. in 2004 and improved by P. Lebrun et al. in 2008. This methodology is based on experimental designs which are used to model retention times of compounds of interest. Then, the prediction accuracy and the optimal separation robustness, including the uncertainty study, were evaluated. Finally, the design space (ICH Q8(R1) guideline) was computed as the probability for a criterion to lie in a selected range of acceptance. Furthermore, the chromatograms were automatically read. Peak detection and peak matching were carried out with a previously developed methodology using independent component analysis published by B. Debrus et al. in 2009. The present successful applications strengthen the high potential of these methodologies for the automated development of chromatographic methods. PMID:21458628
Progress toward a model based approach to the robust design of welded structures
NASA Astrophysics Data System (ADS)
Johnson, Eric M.
Civilization has relied on welded structures to facilitate fabrication and improve our quality of living for the past century. Welds are used in our production of energy, to create infrastructure that we rely upon such as bridges and building, and to fabricate the equipment that makes all of this happen. In short, the joining of two metals through welding has contributed immensely to our society. One problem that has plagued welds is their susceptibility to fatigue failure due to cyclic loading. Fatigue in welded joints is a complicated phenomenon and the subject of fatigue of welded structures been the subject of great study. The goal of the research presented in this dissertation is to improve fatigue life prediction capability by incorporating the effect of the welding process prior to making the structure. The first area examined in this study is the residual stress that is induced during the welding process. If the goal of virtual design and verification of welded structures is to become a reality the residual stress state needs to be known prior to making a product. Computational welding simulation can be used to predict the residual stress state of the welded structure prior to the manufacturing of any part. In order to use computational welding simulation in fatigue life predictions the validity of the results need to be confirmed. This was done in the following dissertation work in two steps, initially by using 3D image correlation to measure the full field displacement of a structure as compared to simulation, and secondly by using neutron diffraction to measure the residual stress after welding as compared to the computational welding simulation results. The results showed that the residual stress state could be predicted with enough accuracy to be used in fatigue life predictions. It is known that the residual stresses redistribute during cyclic loading which can have an impact on their effect on the fatigue life of the structure. The third area this
Single-Case Designs and Qualitative Methods: Applying a Mixed Methods Research Perspective
ERIC Educational Resources Information Center
Hitchcock, John H.; Nastasi, Bonnie K.; Summerville, Meredith
2010-01-01
The purpose of this conceptual paper is to describe a design that mixes single-case (sometimes referred to as single-subject) and qualitative methods, hereafter referred to as a single-case mixed methods design (SCD-MM). Minimal attention has been given to the topic of applying qualitative methods to SCD work in the literature. These two…
A Tutorial Design Process Applied to an Introductory Materials Engineering Course
ERIC Educational Resources Information Center
Rosenblatt, Rebecca; Heckler, Andrew F.; Flores, Katharine
2013-01-01
We apply a "tutorial design process", which has proven to be successful for a number of physics topics, to design curricular materials or "tutorials" aimed at improving student understanding of important concepts in a university-level introductory materials science and engineering course. The process involves the identification…
ERIC Educational Resources Information Center
Krumwiede, Robert William
This paper focuses on making specific connections between basic social and psychological needs of campus residents and the principles of architectural design that can be applied to the design and renovation of educational facilities. Various research was used to select six "principles of social ecology" that were cross-referenced with five design…
Schneider, Johannes; Wollenhaupt, Matthias; Winzenburg, Andreas; Bayer, Tim; Köhler, Jens; Faust, Rüdiger; Baumert, Thomas
2011-05-21
We demonstrate control of electronic population transfer in molecules with the help of appropriately shaped femtosecond laser pulses. To this end we investigate two photosensitizer dyes in solution being prepared in the triplet ground state. Excitation within the triplet system is followed by intersystem crossing and the corresponding singlet fluorescence is monitored as a measure of population transfer in the triplet system. We record control landscapes with respect to the fluorescence intensity on both dyes by a systematic variation of laser pulse shapes combining second order and third order dispersion. In the strong-field regime we find highly structured topologies with large areas of maximum or minimum population transfer being insensitive over a certain range of applied laser intensities thus demonstrating robustness. We then compare our experimental results with simulations on generic molecular potentials by solving the time-dependent Schrödinger equation for excitation with shaped pulses. Control landscapes with respect to population transfer confirm the general trends from experiments. An analysis of regions with maximum or minimum population transfer indicates that coherent processes are responsible for the outcome of our excitation process. The physical mechanisms of joint motion of ground and excited state wave packets or population of a vibrational eigenstate in the excited state permit us to discuss the molecular dynamics in an atom-like picture. PMID:21437344
ERIC Educational Resources Information Center
Shachak, Aviv; Ophir, Ron; Rubin, Eitan
2005-01-01
The need to support bioinformatics training has been widely recognized by scientists, industry, and government institutions. However, the discussion of instructional methods for teaching bioinformatics is only beginning. Here we report on a systematic attempt to design two bioinformatics workshops for graduate biology students on the basis of…
NASA Astrophysics Data System (ADS)
Koma, Zsófia; Székely, Balázs; Dorninger, Peter; Kovács, Gábor
2013-04-01
Due to the need for quantitative analysis of various geomorphological landforms, the importance of fast and effective automatic processing of the different kind of digital terrain models (DTMs) is increasing. The robust plane fitting (segmentation) method, developed at the Institute of Photogrammetry and Remote Sensing at Vienna University of Technology, allows the processing of large 3D point clouds (containing millions of points), performs automatic detection of the planar elements of the surface via parameter estimation, and provides a considerable data reduction for the modeled area. Its geoscientific application allows the modeling of different landforms with the fitted planes as planar facets. In our study we aim to analyze the accuracy of the resulting set of fitted planes in terms of accuracy, model reliability and dependence on the input parameters. To this end we used DTMs of different scales and accuracy: (1) artificially generated 3D point cloud model with different magnitudes of error; (2) LiDAR data with 0.1 m error; (3) SRTM (Shuttle Radar Topography Mission) DTM database with 5 m accuracy; (4) DTM data from HRSC (High Resolution Stereo Camera) of the planet Mars with 10 m error. The analysis of the simulated 3D point cloud with normally distributed errors comprised different kinds of statistical tests (for example Chi-square and Kolmogorov-Smirnov tests) applied on the residual values and evaluation of dependence of the residual values on the input parameters. These tests have been repeated on the real data supplemented with the categorization of the segmentation result depending on the input parameters, model reliability and the geomorphological meaning of the fitted planes. The simulation results show that for the artificially generated data with normally distributed errors the null hypothesis can be accepted based on the residual value distribution being also normal, but in case of the test on the real data the residual value distribution is
Robust optimisation of railway crossing geometry
NASA Astrophysics Data System (ADS)
Wan, Chang; Markine, Valeri; Dollevoet, Rolf
2016-05-01
This paper presents a methodology for improving the crossing (frog) geometry through the robust optimisation approach, wherein the variability of the design parameters within a prescribed tolerance is included in the optimisation problem. Here, the crossing geometry is defined by parameterising the B-spline represented cross-sectional shape and the longitudinal height profile of the nose rail. The dynamic performance of the crossing is evaluated considering the variation of wheel profiles and track alignment. A multipoint approximation method (MAM) is applied in solving the optimisation problem of minimising the contact pressure during the wheel-rail contact and constraining the location of wheel transition at the crossing. To clarify the difference between the robust optimisation and the normal deterministic optimisation approaches, the optimisation problems are solved in both approaches. The results show that the deterministic optimum fails under slight change of the design variables; the robust optimum, however, has improved and robust performance.
Pizarro, C; Martínez-Uruñuela, A; Pérez-Del-Notario, N; González-Sáiz, J M
2008-10-24
A robustness test of a solid-phase microextraction-based method optimised for the simultaneous determination of chloroanisoles and acetyl-chlorophenols implicated in the presence of corky taste in wine has been carried out using a hybrid experimental design. The influence of small changes around the nominal level of four factors (Vs/Vt ratio, extraction temperature, exposure time and sample incubation time) on the measured response were evaluated in order to indicate if the method is robust for the experimental range considered. Moreover, it was also necessary to identify the critical parameters in the validated model in order to keep them under strict control. Experimental design provides an effective approach for robustness testing as a part of the analytical method validation. PMID:18790489
Spasojević Brkić, Vesna K; Veljković, Zorica A; Golubović, Tamara; Brkić, Aleksandar Dj; Kosić Šotić, Ivana
2016-01-01
Procedures in the development process of crane cabins are arbitrary and subjective. Since approximately 42% of incidents in the construction industry are linked to them, there is a need to collect fresh anthropometric data and provide additional recommendations for design. In this paper, dimensioning of the crane cabin interior space was carried out using a sample of 64 crane operators' anthropometric measurements, in the Republic of Serbia, by measuring workspace with 10 parameters using nine measured anthropometric data from each crane operator. This paper applies experiments run via full factorial designs using a combined traditional and Taguchi approach. The experiments indicated which design parameters are influenced by which anthropometric measurements and to what degree. The results are expected to be of use for crane cabin designers and should assist them to design a cabin that may lead to less strenuous sitting postures and fatigue for operators, thus improving safety and accident prevention. PMID:26652099
Saad, Ahmed S; Ismail, Nahla S; Soliman, Marwa; Zaazaa, Hala E
2016-03-01
A sensitive and highly selective stability-indicating gradient HPLC method was developed and validated for simultaneous determination of clorsulon (CLO) and ivermectin (IVM) in the presence of their degradation products. The drugs were subjected to different stress conditions, including acid and alkaline hydrolysis, oxidative, thermal, and photolytic forced degradation. The robustness of the proposed method was assessed using the Plackett-Burman experimental design, the factors affecting system performance were defined, and nonsignificant intervals for the significant factors were determined. The separation was carried out on a ZORBAX SB phenyl analytical column (250 × 4.6 mm id, 5 μm particle size), with gradient elution utilizing 10 mM sodium dihydrogen phosphate and acetonitrile as mobile phase. UV detection was performed for CLO and IVM at 254 nm over a concentration range of 4-140 and 5-50 μg/mL, respectively, with mean percentage recoveries of 99.90 ± 1.30 and 98.59 ± 1.16%, respectively. The proposed method was successfully applied to a pharmaceutical dosage form containing the investigated drugs. The results were statistically compared with the official HPLC methods, and no significant differences were found. PMID:26997479
Mechanisms for Robust Cognition
ERIC Educational Resources Information Center
Walsh, Matthew M.; Gluck, Kevin A.
2015-01-01
To function well in an unpredictable environment using unreliable components, a system must have a high degree of robustness. Robustness is fundamental to biological systems and is an objective in the design of engineered systems such as airplane engines and buildings. Cognitive systems, like biological and engineered systems, exist within…
System Sensitivity Analysis Applied to the Conceptual Design of a Dual-Fuel Rocket SSTO
NASA Technical Reports Server (NTRS)
Olds, John R.
1994-01-01
This paper reports the results of initial efforts to apply the System Sensitivity Analysis (SSA) optimization method to the conceptual design of a single-stage-to-orbit (SSTO) launch vehicle. SSA is an efficient, calculus-based MDO technique for generating sensitivity derivatives in a highly multidisciplinary design environment. The method has been successfully applied to conceptual aircraft design and has been proven to have advantages over traditional direct optimization methods. The method is applied to the optimization of an advanced, piloted SSTO design similar to vehicles currently being analyzed by NASA as possible replacements for the Space Shuttle. Powered by a derivative of the Russian RD-701 rocket engine, the vehicle employs a combination of hydrocarbon, hydrogen, and oxygen propellants. Three primary disciplines are included in the design - propulsion, performance, and weights & sizing. A complete, converged vehicle analysis depends on the use of three standalone conceptual analysis computer codes. Efforts to minimize vehicle dry (empty) weight are reported in this paper. The problem consists of six system-level design variables and one system-level constraint. Using SSA in a 'manual' fashion to generate gradient information, six system-level iterations were performed from each of two different starting points. The results showed a good pattern of convergence for both starting points. A discussion of the advantages and disadvantages of the method, possible areas of improvement, and future work is included.
23 CFR 636.104 - Does this part apply to all Federal-aid design-build projects?
Code of Federal Regulations, 2011 CFR
2011-04-01
... ENGINEERING AND TRAFFIC OPERATIONS DESIGN-BUILD CONTRACTING General § 636.104 Does this part apply to all Federal-aid design-build projects? The provisions of this part apply to all Federal-aid design-build... 23 Highways 1 2011-04-01 2011-04-01 false Does this part apply to all Federal-aid...
Code of Federal Regulations, 2010 CFR
2010-07-01
... Security Committee Security Design Criteria apply to all new Federally owned and leased facilities? 102-81... Interagency Security Committee Security Design Criteria apply to all new Federally owned and leased facilities? No, the Interagency Security Committee Security Design Criteria— (a) Apply to new construction...
Accessible by Design: Applying UDL Principles in a First Year Undergraduate Course
ERIC Educational Resources Information Center
Kumar, Kari Lynne; Wideman, Maureen
2014-01-01
This article presents a case study of a technology-enhanced face-to-face health sciences course in which the principles of Universal Design for Learning (UDL) were applied. Students were offered a variety of means of representation, engagement, and expression throughout the course, and were surveyed and interviewed at the end of the term to…
21 CFR 111.20 - What design and construction requirements apply to your physical plant?
Code of Federal Regulations, 2011 CFR
2011-04-01
... your physical plant? 111.20 Section 111.20 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF... MANUFACTURING, PACKAGING, LABELING, OR HOLDING OPERATIONS FOR DIETARY SUPPLEMENTS Physical Plant and Grounds § 111.20 What design and construction requirements apply to your physical plant? Any physical plant...
ERIC Educational Resources Information Center
Moeller, Jeremy D.; Dattilo, John; Rusch, Frank
2015-01-01
This study examined how specific guidelines and heuristics have been used to identify methodological rigor associated with single-case research designs based on quality indicators developed by Horner et al. Specifically, this article describes how literature reviews have applied Horner et al.'s quality indicators and evidence-based criteria.…
Applying Item Response Theory Methods to Design a Learning Progression-Based Science Assessment
ERIC Educational Resources Information Center
Chen, Jing
2012-01-01
Learning progressions are used to describe how students' understanding of a topic progresses over time and to classify the progress of students into steps or levels. This study applies Item Response Theory (IRT) based methods to investigate how to design learning progression-based science assessments. The research questions of this study are: (1)…
"Design Your Own Disease" Assignment: Teaching Students to Apply Metabolic Pathways
ERIC Educational Resources Information Center
Flynn, Nick
2010-01-01
One of the major focuses of biochemistry courses is metabolic pathways. Although certain aspects of this content may require a rote approach, more applied techniques make these subject areas more interesting. This article describes the use of an assignment, "Design Your Own Disease" to teach students metabolic regulation and biosignaling…
34 CFR 606.5 - How does an institution apply to be designated an eligible institution?
Code of Federal Regulations, 2010 CFR
2010-07-01
... 34 Education 3 2010-07-01 2010-07-01 false How does an institution apply to be designated an eligible institution? 606.5 Section 606.5 Education Regulations of the Offices of the Department of Education (Continued) OFFICE OF POSTSECONDARY EDUCATION, DEPARTMENT OF EDUCATION DEVELOPING...
34 CFR 607.5 - How does an institution apply to be designated an eligible institution?
Code of Federal Regulations, 2010 CFR
2010-07-01
... 34 Education 3 2010-07-01 2010-07-01 false How does an institution apply to be designated an eligible institution? 607.5 Section 607.5 Education Regulations of the Offices of the Department of Education (Continued) OFFICE OF POSTSECONDARY EDUCATION, DEPARTMENT OF EDUCATION STRENGTHENING...
34 CFR 367.10 - How does a designated State agency (DSA) apply for an award?
Code of Federal Regulations, 2011 CFR
2011-07-01
... 34 Education 2 2011-07-01 2010-07-01 true How does a designated State agency (DSA) apply for an award? 367.10 Section 367.10 Education Regulations of the Offices of the Department of Education... LIVING SERVICES FOR OLDER INDIVIDUALS WHO ARE BLIND What Are the Application Requirements? § 367.10...
NASA Technical Reports Server (NTRS)
Thomas, J. M.; Hawk, J. D.
1975-01-01
A generalized concept for cost-effective structural design is introduced. It is assumed that decisions affecting the cost effectiveness of aerospace structures fall into three basic categories: design, verification, and operation. Within these basic categories, certain decisions concerning items such as design configuration, safety factors, testing methods, and operational constraints are to be made. All or some of the variables affecting these decisions may be treated probabilistically. Bayesian statistical decision theory is used as the tool for determining the cost optimum decisions. A special case of the general problem is derived herein, and some very useful parametric curves are developed and applied to several sample structures.
Ruano, M V; Ribes, J; Seco, A; Ferrer, J
2011-01-01
This paper presents a computer tool called DSC (Simulation based Controllers Design) that enables an easy design of control systems and strategies applied to wastewater treatment plants. Although the control systems are developed and evaluated by simulation, this tool aims to facilitate the direct implementation of the designed control system to the PC of the full-scale WWTP (wastewater treatment plants). The designed control system can be programmed in a dedicated control application and can be connected to either the simulation software or the SCADA of the plant. To this end, the developed DSC incorporates an OPC server (OLE for process control) which facilitates an open-standard communication protocol for different industrial process applications. The potential capabilities of the DSC tool are illustrated through the example of a full-scale application. An aeration control system applied to a nutrient removing WWTP was designed, tuned and evaluated with the DSC tool before its implementation in the full scale plant. The control parameters obtained by simulation were suitable for the full scale plant with only few modifications to improve the control performance. With the DSC tool, the control systems performance can be easily evaluated by simulation. Once developed and tuned by simulation, the control systems can be directly applied to the full-scale WWTP. PMID:21330730
Principles of Biomimetic Vascular Network Design Applied to a Tissue-Engineered Liver Scaffold
Hoganson, David M.; Pryor, Howard I.; Spool, Ira D.; Burns, Owen H.; Gilmore, J. Randall
2010-01-01
Branched vascular networks are a central component of scaffold architecture for solid organ tissue engineering. In this work, seven biomimetic principles were established as the major guiding technical design considerations of a branched vascular network for a tissue-engineered scaffold. These biomimetic design principles were applied to a branched radial architecture to develop a liver-specific vascular network. Iterative design changes and computational fluid dynamic analysis were used to optimize the network before mold manufacturing. The vascular network mold was created using a new mold technique that achieves a 1:1 aspect ratio for all channels. In vitro blood flow testing confirmed the physiologic hemodynamics of the network as predicted by computational fluid dynamic analysis. These results indicate that this biomimetic liver vascular network design will provide a foundation for developing complex vascular networks for solid organ tissue engineering that achieve physiologic blood flow. PMID:20001254
Quantitative Feedback Theory (QFT) applied to the design of a rotorcraft flight control system
NASA Technical Reports Server (NTRS)
Hess, R. A.; Gorder, P. J.
1992-01-01
Quantitative Feedback Theory describes a frequency-domain technique for the design of multi-input, multi-output control systems which meet time or frequency domain performance criteria when specified uncertainty exists in the linear description of the vehicle dynamics. Quantitative Feedback Theory is applied to the design of the longitudinal flight control system for a linear uncertain model of the AH-64 rotorcraft. In this model, the uncertainty is assigned, and is assumed to be attributable to actual uncertainty in the dynamic model and to the changes in the vehicle aerodynamic characteristics which occur near hover. The model includes an approximation to the rotor and actuator dynamics. The design example indicates the manner in which handling qualities criteria may be incorporated into the design of realistic rotorcraft control systems in which significant uncertainty exists in the vehicle model.
Applying Monte Carlo Simulation to Launch Vehicle Design and Requirements Verification
NASA Technical Reports Server (NTRS)
Hanson, John M.; Beard, Bernard B.
2010-01-01
This paper is focused on applying Monte Carlo simulation to probabilistic launch vehicle design and requirements verification. The approaches developed in this paper can be applied to other complex design efforts as well. Typically the verification must show that requirement "x" is met for at least "y" % of cases, with, say, 10% consumer risk or 90% confidence. Two particular aspects of making these runs for requirements verification will be explored in this paper. First, there are several types of uncertainties that should be handled in different ways, depending on when they become known (or not). The paper describes how to handle different types of uncertainties and how to develop vehicle models that can be used to examine their characteristics. This includes items that are not known exactly during the design phase but that will be known for each assembled vehicle (can be used to determine the payload capability and overall behavior of that vehicle), other items that become known before or on flight day (can be used for flight day trajectory design and go/no go decision), and items that remain unknown on flight day. Second, this paper explains a method (order statistics) for determining whether certain probabilistic requirements are met or not and enables the user to determine how many Monte Carlo samples are required. Order statistics is not new, but may not be known in general to the GN&C community. The methods also apply to determining the design values of parameters of interest in driving the vehicle design. The paper briefly discusses when it is desirable to fit a distribution to the experimental Monte Carlo results rather than using order statistics.
NASA Astrophysics Data System (ADS)
Bederli Tümay, Aylin; Brouwer, Roy
2007-05-01
In this paper, we investigate the economic benefits associated with public investments in wastewater treatment in one of the special protected areas along Turkey's touristic Mediterranean coast, the Köyceǧiz-Dalyan watershed. The benefits, measured in terms of boatable, fishable, swimmable and drinkable water quality, are estimated using a public survey format following the contingent valuation (CV) method. The study presented here is the first of its kind in Turkey. The study's main objective is to assess public perception, understanding, and valuation of improved wastewater treatment facilities in the two largest population centers in the watershed, facing the same water pollution problems as a result of lack of appropriate wastewater treatment. We test the validity and reliability of the application of the CV methodology to this specific environmental problem in a rural transition economy and evaluate the transferability of the results within the watershed. In order to facilitate willingness to pay (WTP) value elicitation we apply a novel dichotomous choice procedure where bid design takes place a posteriori instead of a priori. The statistical efficiency of different bid vectors is evaluated in terms of the estimated welfare measures' mean square errors using Monte Carlo simulation. The robustness of bid function specification is analyzed through average WTP and standard deviation estimated using parametric and nonparametric methods.
Efficient high-resolution RF pulse design applied to simultaneous multi-slice excitation
NASA Astrophysics Data System (ADS)
Aigner, Christoph Stefan; Clason, Christian; Rund, Armin; Stollberger, Rudolf
2016-02-01
RF pulse design via optimal control is typically based on gradient and quasi-Newton approaches and therefore suffers from slow convergence. We present a flexible and highly efficient method that uses exact second-order information within a globally convergent trust-region CG-Newton method to yield an improved convergence rate. The approach is applied to the design of RF pulses for single- and simultaneous multi-slice (SMS) excitation and validated using phantom and in vivo experiments on a 3 T scanner using a modified gradient echo sequence.
Designing and applying treatment technologies: Remediation of chlorinated and recalcitrant compounds
1998-12-31
This book combines technical guidance on some of the newer remediation technologies with case studies on remediation strategies that have worked effectively at real-world sites. Chapters cover bench-scale testing, modeling and performance evaluation for permeable barriers, barrier design and construction, remediation of explosives and nitroaromatics, remediation of pesticides and herbicides, regulation and remediation of PCBs/dioxins, emerging technologies, and applying multiple remediation technologies.
Selection of a turbine cooling system applying multi-disciplinary design considerations.
Glezer, B
2001-05-01
The presented paper describes a multi-disciplinary cooling selection approach applied to major gas turbine engine hot section components, including turbine nozzles, blades, discs, combustors and support structures, which maintain blade tip clearances. The paper demonstrates benefits of close interaction between participating disciplines starting from early phases of the hot section development. The approach targets advancements in engine performance and cost by optimizing the design process, often requiring compromises within individual disciplines. PMID:11460630
NASA Astrophysics Data System (ADS)
Parameswaran, Arun P.; Ananthakrishnan, B.; Gangadharan, K. V.
2015-10-01
Real physical vibrating smart systems exhibit a lot of nonlinearities in their dynamics. Undesirable vibrations, particularly in the regions of first as well as second resonance, play a very important role in deteriorating the stability of the system as well as its operational efficiency. The work presented in the paper focuses on an analytical technique of mathematical modeling of a vibrating piezoelectric laminate cantilever beam which is considered to be the smart system. The natural frequencies of the vibrating smart system are determined from the ANSYS simulation studies and experimentally, it is found that the vibrations induced voltage is maximum at the first followed by the second natural frequencies. Hence, the smart system is modeled analytically through finite element technique using the Euler-Bernoulli beam theory for the first two flexural modes of vibrations. To account for the possible nonlinearities, a suitable robust controller is designed based on sliding mode technique. Simulation studies on the developed analytical model indicated a high performance of the designed controller in controlling the vibrations at first and second resonance regions. Also, the designed controller was found to be effective in its operations when the excitation varied over a large range covering the first two natural frequencies. In the final stage, the designed robust controller was successfully prototyped on a Field Programmable Gate Array (FPGA) platform using LabVIEW coupled with Compact Reconfigurable Input Output (cRIO-9022) controller configured in its FPGA interface mode and the resulting robust FPGA controller successfully controlled the occurring system vibrations.
20 CFR 669.640 - What is the process for applying for designation as an MSFW youth program grantee?
Code of Federal Regulations, 2014 CFR
2014-04-01
... designation as an MSFW youth program grantee? 669.640 Section 669.640 Employees' Benefits EMPLOYMENT AND... THE WORKFORCE INVESTMENT ACT The MSFW Youth Program § 669.640 What is the process for applying for designation as an MSFW youth program grantee? (a) To apply for designation as an MSFW youth program...
20 CFR 669.640 - What is the process for applying for designation as an MSFW youth program grantee?
Code of Federal Regulations, 2012 CFR
2012-04-01
... designation as an MSFW youth program grantee? 669.640 Section 669.640 Employees' Benefits EMPLOYMENT AND... THE WORKFORCE INVESTMENT ACT The MSFW Youth Program § 669.640 What is the process for applying for designation as an MSFW youth program grantee? (a) To apply for designation as an MSFW youth program...
20 CFR 669.640 - What is the process for applying for designation as an MSFW youth program grantee?
Code of Federal Regulations, 2011 CFR
2011-04-01
... designation as an MSFW youth program grantee? 669.640 Section 669.640 Employees' Benefits EMPLOYMENT AND... WORKFORCE INVESTMENT ACT The MSFW Youth Program § 669.640 What is the process for applying for designation as an MSFW youth program grantee? (a) To apply for designation as an MSFW youth program...
20 CFR 669.640 - What is the process for applying for designation as an MSFW youth program grantee?
Code of Federal Regulations, 2010 CFR
2010-04-01
... designation as an MSFW youth program grantee? 669.640 Section 669.640 Employees' Benefits EMPLOYMENT AND... WORKFORCE INVESTMENT ACT The MSFW Youth Program § 669.640 What is the process for applying for designation as an MSFW youth program grantee? (a) To apply for designation as an MSFW youth program...
20 CFR 669.640 - What is the process for applying for designation as an MSFW youth program grantee?
Code of Federal Regulations, 2013 CFR
2013-04-01
... designation as an MSFW youth program grantee? 669.640 Section 669.640 Employees' Benefits EMPLOYMENT AND... THE WORKFORCE INVESTMENT ACT The MSFW Youth Program § 669.640 What is the process for applying for designation as an MSFW youth program grantee? (a) To apply for designation as an MSFW youth program...
Applying design principles to fusion reactor configurations for propulsion in space
NASA Technical Reports Server (NTRS)
Carpenter, Scott A.; Deveny, Marc E.; Schulze, Norman R.
1993-01-01
We applied three design principles (DPs) to adapt and optimize three candidate-terrestrial-fusion-reactor configurations for propulsion in space. The three design principles are: (1) provide maximum direct access to space for waste radiation, (2) operate components as passive radiators to minimize cooling-system mass, and (3) optimize the plasma fuel, fuel mix, and temperature for best specific Jet power. The three candidate-terrestrial-fusion-reactor configurations are: (1) the thermal-barrier-tandem-mirror (TBTM), (2) field-reversed-mirror (FRM), and (3) levitated-dipole-field (LDF). The resulting three candidate-space-fusion-propulsion systems have their initial-mass-to-LEO minimized and their specific jet power and reusability maximized. We performed a preliminary rating of these configurations and concluded that the leading engineering-design solution to space fusion propulsion is a modified TBTM that we call the Mirror Fusion Propulsion System.
Applying design principles to fusion reactor configurations for propulsion in space
NASA Astrophysics Data System (ADS)
Carpenter, Scott A.; Deveny, Marc E.; Schulze, Norman R.
1993-06-01
We applied three design principles (DPs) to adapt and optimize three candidate-terrestrial-fusion-reactor configurations for propulsion in space. The three design principles are: (1) provide maximum direct access to space for waste radiation, (2) operate components as passive radiators to minimize cooling-system mass, and (3) optimize the plasma fuel, fuel mix, and temperature for best specific Jet power. The three candidate-terrestrial-fusion-reactor configurations are: (1) the thermal-barrier-tandem-mirror (TBTM), (2) field-reversed-mirror (FRM), and (3) levitated-dipole-field (LDF). The resulting three candidate-space-fusion-propulsion systems have their initial-mass-to-LEO minimized and their specific jet power and reusability maximized. We performed a preliminary rating of these configurations and concluded that the leading engineering-design solution to space fusion propulsion is a modified TBTM that we call the Mirror Fusion Propulsion System.
Applying design principles to fusion reactor configurations for propulsion in space
NASA Technical Reports Server (NTRS)
Carpenter, Scott A.; Deveny, Marc E.; Schulze, Norman R.
1993-01-01
The application of fusion power to space propulsion requires rethinking the engineering-design solution to controlled-fusion energy. Whereas the unit cost of electricity (COE) drives the engineering-design solution for utility-based fusion reactor configurations; initial mass to low earth orbit (IMLEO), specific jet power (kW(thrust)/kg(engine)), and reusability drive the engineering-design solution for successful application of fusion power to space propulsion. We applied three design principles (DP's) to adapt and optimize three candidate-terrestrial-fusion-reactor configurations for propulsion in space. The three design principles are: provide maximum direct access to space for waste radiation, operate components as passive radiators to minimize cooling-system mass, and optimize the plasma fuel, fuel mix, and temperature for best specific jet power. The three candidate terrestrial fusion reactor configurations are: the thermal barrier tandem mirror (TBTM), field reversed mirror (FRM), and levitated dipole field (LDF). The resulting three candidate space fusion propulsion systems have their IMLEO minimized and their specific jet power and reusability maximized. We performed a preliminary rating of these configurations and concluded that the leading engineering-design solution to space fusion propulsion is a modified TBTM that we call the Mirror Fusion Propulsion System (MFPS).
NASA Astrophysics Data System (ADS)
Sancho-García, J. C.
2009-01-01
Quantum-chemical calculations of energy difference between ethene/benzenium ion complex and its fragments are reported. We pursue the greatest accuracy by tackling first a focal-point analysis to robustly estimate the fleetingness of the molecule. Previous calculations showed how MP2 failed to locate the complex on the energy surface due to basis sets superposition error, and thus predicting ethylbenzenium ion as the energetically favoured system. However, MP2-based balanced treatment of intra- and inter-pair correlation effects (SCS-MP2) greatly improves the results. DFT studies with dispersion corrections, including double-hybrid functionals, are presented and further assessed. Finally, IR signatures of involved species are also compared.
The Enzyme Portal: a case study in applying user-centred design methods in bioinformatics
2013-01-01
User-centred design (UCD) is a type of user interface design in which the needs and desires of users are taken into account at each stage of the design process for a service or product; often for software applications and websites. Its goal is to facilitate the design of software that is both useful and easy to use. To achieve this, you must characterise users’ requirements, design suitable interactions to meet their needs, and test your designs using prototypes and real life scenarios. For bioinformatics, there is little practical information available regarding how to carry out UCD in practice. To address this we describe a complete, multi-stage UCD process used for creating a new bioinformatics resource for integrating enzyme information, called the Enzyme Portal (http://www.ebi.ac.uk/enzymeportal). This freely-available service mines and displays data about proteins with enzymatic activity from public repositories via a single search, and includes biochemical reactions, biological pathways, small molecule chemistry, disease information, 3D protein structures and relevant scientific literature. We employed several UCD techniques, including: persona development, interviews, ‘canvas sort’ card sorting, user workflows, usability testing and others. Our hope is that this case study will motivate the reader to apply similar UCD approaches to their own software design for bioinformatics. Indeed, we found the benefits included more effective decision-making for design ideas and technologies; enhanced team-working and communication; cost effectiveness; and ultimately a service that more closely meets the needs of our target audience. PMID:23514033
The Enzyme Portal: a case study in applying user-centred design methods in bioinformatics.
de Matos, Paula; Cham, Jennifer A; Cao, Hong; Alcántara, Rafael; Rowland, Francis; Lopez, Rodrigo; Steinbeck, Christoph
2013-01-01
User-centred design (UCD) is a type of user interface design in which the needs and desires of users are taken into account at each stage of the design process for a service or product; often for software applications and websites. Its goal is to facilitate the design of software that is both useful and easy to use. To achieve this, you must characterise users' requirements, design suitable interactions to meet their needs, and test your designs using prototypes and real life scenarios.For bioinformatics, there is little practical information available regarding how to carry out UCD in practice. To address this we describe a complete, multi-stage UCD process used for creating a new bioinformatics resource for integrating enzyme information, called the Enzyme Portal (http://www.ebi.ac.uk/enzymeportal). This freely-available service mines and displays data about proteins with enzymatic activity from public repositories via a single search, and includes biochemical reactions, biological pathways, small molecule chemistry, disease information, 3D protein structures and relevant scientific literature.We employed several UCD techniques, including: persona development, interviews, 'canvas sort' card sorting, user workflows, usability testing and others. Our hope is that this case study will motivate the reader to apply similar UCD approaches to their own software design for bioinformatics. Indeed, we found the benefits included more effective decision-making for design ideas and technologies; enhanced team-working and communication; cost effectiveness; and ultimately a service that more closely meets the needs of our target audience. PMID:23514033
NASA Astrophysics Data System (ADS)
Ball, Nicholas M.; Brunner, Robert J.; Myers, Adam D.; Tcheng, David
2006-10-01
We provide classifications for all 143 million nonrepeat photometric objects in the Third Data Release of the SDSS using decision trees trained on 477,068 objects with SDSS spectroscopic data. We demonstrate that these star/galaxy classifications are expected to be reliable for approximately 22 million objects with r<~20. The general machine learning environment Data-to-Knowledge and supercomputing resources enabled extensive investigation of the decision tree parameter space. This work presents the first public release of objects classified in this way for an entire SDSS data release. The objects are classified as either galaxy, star, or nsng (neither star nor galaxy), with an associated probability for each class. To demonstrate how to effectively make use of these classifications, we perform several important tests. First, we detail selection criteria within the probability space defined by the three classes to extract samples of stars and galaxies to a given completeness and efficiency. Second, we investigate the efficacy of the classifications and the effect of extrapolating from the spectroscopic regime by performing blind tests on objects in the SDSS, 2dFGRS, and 2QZ surveys. Given the photometric limits of our spectroscopic training data, we effectively begin to extrapolate past our star-galaxy training set at r~18. By comparing the number counts of our training sample with the classified sources, however, we find that our efficiencies appear to remain robust to r~20. As a result, we expect our classifications to be accurate for 900,000 galaxies and 6.7 million stars and remain robust via extrapolation for a total of 8.0 million galaxies and 13.9 million stars.
Robust detection-isolation-accommodation for sensor failures
NASA Astrophysics Data System (ADS)
Weiss, J. L.; Pattipati, K. R.; Willsky, A. S.; Eterno, J. S.; Crawford, J. T.
1985-09-01
The results of a one year study to: (1) develop a theory for Robust Failure Detection and Identification (FDI) in the presence of model uncertainty, (2) develop a design methodology which utilizes the robust FDI ththeory, (3) apply the methodology to a sensor FDI problem for the F-100 jet engine, and (4) demonstrate the application of the theory to the evaluation of alternative FDI schemes are presented. Theoretical results in statistical discrimination are used to evaluate the robustness of residual signals (or parity relations) in terms of their usefulness for FDI. Furthermore, optimally robust parity relations are derived through the optimization of robustness metrics. The result is viewed as decentralization of the FDI process. A general structure for decentralized FDI is proposed and robustness metrics are used for determining various parameters of the algorithm.
Robust detection-isolation-accommodation for sensor failures
NASA Technical Reports Server (NTRS)
Weiss, J. L.; Pattipati, K. R.; Willsky, A. S.; Eterno, J. S.; Crawford, J. T.
1985-01-01
The results of a one year study to: (1) develop a theory for Robust Failure Detection and Identification (FDI) in the presence of model uncertainty, (2) develop a design methodology which utilizes the robust FDI ththeory, (3) apply the methodology to a sensor FDI problem for the F-100 jet engine, and (4) demonstrate the application of the theory to the evaluation of alternative FDI schemes are presented. Theoretical results in statistical discrimination are used to evaluate the robustness of residual signals (or parity relations) in terms of their usefulness for FDI. Furthermore, optimally robust parity relations are derived through the optimization of robustness metrics. The result is viewed as decentralization of the FDI process. A general structure for decentralized FDI is proposed and robustness metrics are used for determining various parameters of the algorithm.
Applying ILT mask synthesis for co-optimizing design rules and DSA process characteristics
NASA Astrophysics Data System (ADS)
Dam, Thuc; Stanton, William
2014-03-01
During early stage development of a DSA process, there are many unknown interactions between design, DSA process, RET, and mask synthesis. The computational resolution of these unknowns can guide development towards a common process space whereby manufacturing success can be evaluated. This paper will demonstrate the use of existing Inverse Lithography Technology (ILT) to co-optimize the multitude of parameters. ILT mask synthesis will be applied to a varied hole design space in combination with a range of DSA model parameters under different illumination and RET conditions. The design will range from 40 nm pitch doublet to random DSA designs with larger pitches, while various effective DSA characteristics of shrink bias and corner smoothing will be assumed for the DSA model during optimization. The co-optimization of these design parameters and process characteristics under different SMO solutions and RET conditions (dark/bright field tones and binary/PSM mask types) will also help to provide a complete process mapping of possible manufacturing options. The lithographic performances for masks within the optimized parameter space will be generated to show a common process space with the highest possibility for success.
Robust tooth surface reconstruction by iterative deformation.
Jiang, Xiaotong; Dai, Ning; Cheng, Xiaosheng; Wang, Jun; Peng, Qingjin; Liu, Hao; Cheng, Cheng
2016-01-01
Digital design technologies have been applied extensively in dental medicine, especially in the field of dental restoration. The all-ceramic crown is an important restoration type of dental CAD systems. This paper presents a robust tooth surface reconstruction algorithm for all-ceramic crown design. The algorithm involves three necessary steps: standard tooth initial positioning and division; salient feature point extraction using Morse theory; and standard tooth deformation using iterative Laplacian Surface Editing and mesh stitching. This algorithm can retain the morphological features of the tooth surface well. It is robust and suitable for almost all types of teeth, including incisor, canine, premolar, and molar. Moreover, it allows dental technicians to use their own preferred library teeth for reconstruction. The algorithm has been successfully integrated in our Dental CAD system, more than 1000 clinical cases have been tested to demonstrate the robustness and effectiveness of the proposed algorithm. PMID:26638148
NASA Astrophysics Data System (ADS)
Li, Zhifu; Hu, Yueming; Li, Di
2016-08-01
For a class of linear discrete-time uncertain systems, a feedback feed-forward iterative learning control (ILC) scheme is proposed, which is comprised of an iterative learning controller and two current iteration feedback controllers. The iterative learning controller is used to improve the performance along the iteration direction and the feedback controllers are used to improve the performance along the time direction. First of all, the uncertain feedback feed-forward ILC system is presented by an uncertain two-dimensional Roesser model system. Then, two robust control schemes are proposed. One can ensure that the feedback feed-forward ILC system is bounded-input bounded-output stable along time direction, and the other can ensure that the feedback feed-forward ILC system is asymptotically stable along time direction. Both schemes can guarantee the system is robust monotonically convergent along the iteration direction. Third, the robust convergent sufficient conditions are given, which contains a linear matrix inequality (LMI). Moreover, the LMI can be used to determine the gain matrix of the feedback feed-forward iterative learning controller. Finally, the simulation results are presented to demonstrate the effectiveness of the proposed schemes.
Zwickl, Titus; Carleer, Bart; Kubli, Waldemar
2005-08-05
In the past decade, sheet metal forming simulation became a well established tool to predict the formability of parts. In the automotive industry, this has enabled significant reduction in the cost and time for vehicle design and development, and has helped to improve the quality and performance of vehicle parts. However, production stoppages for troubleshooting and unplanned die maintenance, as well as production quality fluctuations continue to plague manufacturing cost and time. The focus therefore has shifted in recent times beyond mere feasibility to robustness of the product and process being engineered. Ensuring robustness is the next big challenge for the virtual tryout / simulation technology.We introduce new methods, based on systematic stochastic simulations, to visualize the behavior of the part during the whole forming process -- in simulation as well as in production. Sensitivity analysis explains the response of the part to changes in influencing parameters. Virtual tryout allows quick exploration of changed designs and conditions. Robust design and manufacturing guarantees quality and process capability for the production process. While conventional simulations helped to reduce development time and cost by ensuring feasible processes, robustness engineering tools have the potential for far greater cost and time savings.Through examples we illustrate how expected and unexpected behavior of deep drawing parts may be tracked down, identified and assigned to the influential parameters. With this knowledge, defects can be eliminated or springback can be compensated e.g.; the response of the part to uncontrollable noise can be predicted and minimized. The newly introduced methods enable more reliable and predictable stamping processes in general.
Wantuck, P. J.; Hollen, R. M.
2002-01-01
This paper provides an overview of some design and automation-related projects ongoing within the Applied Engineering Technologies (AET) Group at Los Alamos National Laboratory. AET uses a diverse set of technical capabilities to develop and apply processes and technologies to applications for a variety of customers both internal and external to the Laboratory. The Advanced Recovery and Integrated Extraction System (ARIES) represents a new paradigm for the processing of nuclear material from retired weapon systems in an environment that seeks to minimize the radiation dose to workers. To achieve this goal, ARIES relies upon automation-based features to handle and process the nuclear material. Our Chemical Process Development Team specializes in fuzzy logic and intelligent control systems. Neural network technology has been utilized in some advanced control systems developed by team members. Genetic algorithms and neural networks have often been applied for data analysis. Enterprise modeling, or discrete event simulation, as well as chemical process simulation has been employed for chemical process plant design. Fuel cell research and development has historically been an active effort within the AET organization. Under the principal sponsorship of the Department of Energy, the Fuel Cell Team is now focusing on technologies required to produce fuel cell compatible feed gas from reformation of a variety of conventional fuels (e.g., gasoline, natural gas), principally for automotive applications. This effort involves chemical reactor design and analysis, process modeling, catalyst analysis, as well as full scale system characterization and testing. The group's Automation and Robotics team has at its foundation many years of experience delivering automated and robotic systems for nuclear, analytical chemistry, and bioengineering applications. As an integrator of commercial systems and a developer of unique custom-made systems, the team currently supports the automation
Robust hyperchaotic synchronization via analog transmission line
NASA Astrophysics Data System (ADS)
Sadoudi, S.; Tanougast, C.
2016-02-01
In this paper, a novel experimental chaotic synchronization technique via analog transmission is discussed. We demonstrate through Field-Programmable Gate Array (FPGA) implementation design the robust synchronization of two embedded hyperchaotic Lorenz generators interconnected with an analog transmission line. The basic idea of this work consists in combining a numerical generation of chaos and transmitting it with an analog signal. The numerical chaos allows to overcome the callback parameter mismatch problem and the analog transmission offers robust data security. As application, this technique can be applied to all families of chaotic systems including time-delayed chaotic systems.
Ruggedness and robustness testing.
Dejaegher, Bieke; Heyden, Yvan Vander
2007-07-27
Due to the strict regulatory requirements, especially in pharmaceutical analysis, analysis results with an acceptable quality should be reported. Thus, a proper validation of the measurement method is required. In this context, ruggedness and robustness testing becomes increasingly more important. In this review, the definitions of ruggedness and robustness are given, followed by a short explanation of the different approaches applied to examine the ruggedness or the robustness of an analytical method. Then, case studies, describing ruggedness or robustness tests of high-performance liquid chromatographic (HPLC), capillary electrophoretic (CE), gas chromatographic (GC), supercritical fluid chromatographic (SFC), and ultra-performance liquid chromatographic (UPLC) assay methods, are critically reviewed and discussed. Mainly publications of the last 10 years are considered. PMID:17379230
Identification and robust control of an experimental servo motor.
Adam, E J; Guestrin, E D
2002-04-01
In this work, the design of a robust controller for an experimental laboratory-scale position control system based on a dc motor drive as well as the corresponding identification and robust stability analysis are presented. In order to carry out the robust design procedure, first, a classic closed-loop identification technique is applied and then, the parametrization by internal model control is used. The model uncertainty is evaluated under both parametric and global representation. For the latter case, an interesting discussion about the conservativeness of this description is presented by means of a comparison between the uncertainty disk and the critical perturbation radius approaches. Finally, conclusions about the performance of the experimental system with the robust controller are discussed using comparative graphics of the controlled variable and the Nyquist stability margin as a robustness measurement. PMID:12071255
Evolving Robust Gene Regulatory Networks
Noman, Nasimul; Monjo, Taku; Moscato, Pablo; Iba, Hitoshi
2015-01-01
Design and implementation of robust network modules is essential for construction of complex biological systems through hierarchical assembly of ‘parts’ and ‘devices’. The robustness of gene regulatory networks (GRNs) is ascribed chiefly to the underlying topology. The automatic designing capability of GRN topology that can exhibit robust behavior can dramatically change the current practice in synthetic biology. A recent study shows that Darwinian evolution can gradually develop higher topological robustness. Subsequently, this work presents an evolutionary algorithm that simulates natural evolution in silico, for identifying network topologies that are robust to perturbations. We present a Monte Carlo based method for quantifying topological robustness and designed a fitness approximation approach for efficient calculation of topological robustness which is computationally very intensive. The proposed framework was verified using two classic GRN behaviors: oscillation and bistability, although the framework is generalized for evolving other types of responses. The algorithm identified robust GRN architectures which were verified using different analysis and comparison. Analysis of the results also shed light on the relationship among robustness, cooperativity and complexity. This study also shows that nature has already evolved very robust architectures for its crucial systems; hence simulation of this natural process can be very valuable for designing robust biological systems. PMID:25616055
23 CFR 636.104 - Does this part apply to all Federal-aid design-build projects?
Code of Federal Regulations, 2010 CFR
2010-04-01
... 23 Highways 1 2010-04-01 2010-04-01 false Does this part apply to all Federal-aid design-build projects? 636.104 Section 636.104 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS DESIGN-BUILD CONTRACTING General § 636.104 Does this part apply to...
Pandya, Darpan N; Bhatt, Nikunj; An, Gwang Il; Ha, Yeong Su; Soni, Nisarg; Lee, Hochun; Lee, Yong Jin; Kim, Jung Young; Lee, Woonghee; Ahn, Heesu; Yoo, Jeongsoo
2014-09-11
The first macrocyclic bifunctional chelator incorporating propylene cross-bridge was efficiently synthesized from cyclam in seven steps. After the introduction of an extra functional group for facile conjugation onto the propylene cross-bridge, the two carboxylic acid pendants could contribute to strong coordination of Cu(II) ions, leading to a robust Cu complex. The cyclic RGD peptide conjugate of PCB-TE2A-NCS was prepared and successfully radiolabeled with (64)Cu ion. The radiolabeled peptide conjugate was evaluated in vivo through a biodistribution study and animal PET imaging to demonstrate high tumor uptake with low background. PMID:25137619
Vaseem, Mohammad; McKerricher, Garret; Shamim, Atif
2016-01-13
Currently, silver-nanoparticle-based inkjet ink is commercially available. This type of ink has several serious problems such as a complex synthesis protocol, high cost, high sintering temperatures (∼200 °C), particle aggregation, nozzle clogging, poor shelf life, and jetting instability. For the emerging field of printed electronics, these shortcomings in conductive inks are barriers for their widespread use in practical applications. Formulating particle-free silver inks has potential to solve these issues and requires careful design of the silver complexation. The ink complex must meet various requirements, such as in situ reduction, optimum viscosity, storage and jetting stability, smooth uniform sintered films, excellent adhesion, and high conductivity. This study presents a robust formulation of silver-organo-complex (SOC) ink, where complexing molecules act as reducing agents. The 17 wt % silver loaded ink was printed and sintered on a wide range of substrates with uniform surface morphology and excellent adhesion. The jetting stability was monitored for 5 months to confirm that the ink was robust and highly stable with consistent jetting performance. Radio frequency inductors, which are highly sensitive to metal quality, were demonstrated as a proof of concept on flexible PEN substrate. This is a major step toward producing high-quality electronic components with a robust inkjet printing process. PMID:26713357
Karimi, Mohammad; Aboufazeli, Forouzan; Zhad, Hamid Reza Lotfi Zadeh; Sadeghi, Omid; Najafi, Ezzatollah
2015-01-01
The application of modified magnetic nanoparticles in extraction of trace Hg was investigated. For this purpose, surfaces of magnetic nanoparticles were modified by 2-picolamine and then utilized as a solid-phase sorbent for Hg(II) extraction. A statistical method, based on surface response design, has been used for the optimization of Hg ion elution from the magnetic nanoparticles. The sorbed Hg ions were eluted quantitatively with 5.5 mL of a solution containing 0.8 M HCl and 0.08 M EDTA after 12 min. The recovery value in this method was 98.6% with RSD of 1.4%, and the obtained LOD was 0.01 ng/mL. The preconcentration factor was calculated to be 179. The method was applied to the determination of hair Hg content for biomonitoring purposes. PMID:25857894
Basis of human factors methodology applied in the Westinghouse AP600 design
Carrera, J.P.; Easter, J.R. )
1992-01-01
The incident at Three Mile Island Unit 2 brought about an awareness that there is a need for a new perspective on nuclear power plant operator performance. It was discerned that besides executing control actions, the operator needs an additional role, that of systems supervisor-someone who considers plant health at the functional level of how all the plant processes are related and how they perform with regard to the high-level operational goals of the plant. Westinghouse has taken the initiative to apply these ideas in dealing with the operator by studying the work of Rasmussen of Denmark's Riso Laboratory, regarding knowledge-based behavior and the requirements for supporting the cognitive processes required of an operator. This has led to the Westinghouse Man-Machine-Interface System (MMIS) design process.
NASA Astrophysics Data System (ADS)
Oudadesse, H.; Derrien, A. C.; Lucas-Girot, A.
2005-09-01
Composites studied in this work are the associations of aluminosilicates and 13% of calcium phosphates. These composites present great interest. They are destined to be applied in biomedical field, particularly in orthopedic or jawbone surgery. Calcium phosphates are composed of HA (hydroxyapatite) and TCP (tricalcic phosphate). The success of synthesised bony biomaterials depends on two determinant factors: the porosity (which facilitate the cells deposition and the vascularisation) and the compressive strength (which permits the support of body charge). In this way, a statistical experimental design was employed to quantify the influence of these two synthesis parameters. It concerns the effect of the K{2}O/SiO{2} molecular ratio (X1) and the effect of the calcium phosphate (HA/TCP) weight % (X2). The K{2}O/SiO{2} molecular ratio characterises the synthesis of the aluminosilicate. It varies between two limit levels: the stoichiometric ratio K{2}O/SiO{2 }= 0.54 corresponding to: X1 = - 1 and the ratio K{2}O/SiO{2 }= 0.80 corresponding to X1 = 1. In bony biomaterials field, various calcium phosphates are commonly used as biomaterials. In our previous works, the influence of the commercial hydroxyapatite HA and tri-calcium phosphate TCP (13 wt%) addition was investigated. To study the effect of calcium phosphate composition, the weight percentage of mixing HA and TCP varied between two levels: the composite aluminosilicate with 13 wt% of HA (X2 = -1) and the composite aluminosilicate with 13 wt% of TCP (X2 = 1). Eight samples were studied. The statistical experimental design predicted answer surfaces for compressive strength and percentage of porosity. After the validation of models, it was possible to determine composite which presents best compromise between percentage of porosity and compressive strength. This composite will be evaluated by “in-vitro” and “in-vivo” studies to investigate its potential for forthcoming applied as biomaterial.
Schmidt, Alexander H; Stanic, Mijo; Molnár, Imre
2014-03-01
Purity testing of the active pharmaceutical ingredient (API) pramipexole is performed using an official (compendial) and harmonized method published in the European Pharmacopeia (E.P.) and United States Pharmacopeia (USP). According to this monograph the successful chromatographic separation of the API from impurities is achieved on a C18 column with gradient elution of an ion pairing buffer of pH 3.0 (mobile phase A) and acetonitrile (mobile phase B). Although not recommended in general, compendial methods are often adapted for purity testing of generic formulations. In this paper a novel approach to evaluate method robustness of an adapted method - prior of full method validation - is described. Based on Quality-by-Design (QbD) principles, a small number of experiments are performed, which after entering them into a chromatography modeling software allow to visualize a multidimensional "Design Space", a region, in which changes in method parameters will not significantly affect the results as defined in the ICH guideline Q8(R2) leading to a more flexible method handling in routine analysis. For two different recommended C18 columns a multidimensional Design Space (Method Operating Design Region, MODR) was constructed to study the robustness of the adapted method with a newly developed Robustness Module. In a full factorial design the following six parameters were varied at three levels (low, nominal, high): gradient time, temperature, pH of the aqueous eluent (A), flow rate, start- and end concentration of the organic mobile phase component (eluent B). The resulting 3(6)=729 experiments were performed in silico from the previously constructed models for Design Space in less than 1min and showed that the required resolution of 2.0 could not be reached in all experiments for the two columns which were recommended by the E.P. (failure rate 25% and 16%, respectively). However, by adjusting the gradient time, we were able to fulfill the requirements with a failure
Pallagi, Edina; Karimi, Keyhaneh; Ambrus, Rita; Szabó-Révész, Piroska; Csóka, Ildikó
2016-09-10
The current work outlines the application of an up-to-date and regulatory-based pharmaceutical quality management method, applied as a new development concept in the process of formulating dry powder inhalation systems (DPIs). According to the Quality by Design (QbD) methodology and Risk Assessment (RA) thinking, a mannitol based co-spray dried formula was produced as a model dosage form with meloxicam as the model active agent. The concept and the elements of the QbD approach (regarding its systemic, scientific, risk-based, holistic, and proactive nature with defined steps for pharmaceutical development), as well as the experimental drug formulation (including the technological parameters assessed and the methods and processes applied) are described in the current paper. Findings of the QbD based theoretical prediction and the results of the experimental development are compared and presented. Characteristics of the developed end-product were in correlation with the predictions, and all data were confirmed by the relevant results of the in vitro investigations. These results support the importance of using the QbD approach in new drug formulation, and prove its good usability in the early development process of DPIs. This innovative formulation technology and product appear to have a great potential in pulmonary drug delivery. PMID:27386791
Robust optimization of front members in a full frontal car impact
NASA Astrophysics Data System (ADS)
Aspenberg (né Lönn), David; Jergeus, Johan; Nilsson, Larsgunnar
2013-03-01
In the search for lightweight automobile designs, it is necessary to assure that robust crashworthiness performance is achieved. Structures that are optimized to handle a finite number of load cases may perform poorly when subjected to various dispersions. Thus, uncertainties must be accounted for in the optimization process. This article presents an approach to optimization where all design evaluations include an evaluation of the robustness. Metamodel approximations are applied both to the design space and the robustness evaluations, using artifical neural networks and polynomials, respectively. The features of the robust optimization approach are displayed in an analytical example, and further demonstrated in a large-scale design example of front side members of a car. Different optimization formulations are applied and it is shown that the proposed approach works well. It is also concluded that a robust optimization puts higher demands on the finite element model performance than normally.
ERIC Educational Resources Information Center
Metz, Kathleen E.
2011-01-01
This study examines first graders' epistemic reasoning, in tacit "practical epistemologies" reflected in thinking about an investigation of their own design. I analyzed children's epistemic reasoning, following a design experiment scaffolding increasing regulation of scientific inquiry in a domain they studied in depth. Participants consisted of…
Design of Astrometric Mission (JASMINE) by Applying Model Driven System Engineering
NASA Astrophysics Data System (ADS)
Yamada, Y.; Miyashita, H.; Nakamura, H.; Suenaga, K.; Kamiyoshi, S.; Tsuiki, A.
2010-12-01
We are planning space astrometric satellite mission named JASMINE. The target accuracy of parallaxes in JASMINE observation is 10 micro arc second, which corresponds to 1 nm scale on the focal plane. It is very hard to measure the 1 nm scale deformation of focal plane. Eventually, we need to add the deformation to the observation equations when estimating stellar astrometric parameters, which requires considering many factors such as instrument models and observation data analysis. In this situation, because the observation equations become more complex, we may reduce the stability of the hardware, nevertheless, we require more samplings due to the lack of rigidity of each estimation. This mission imposes a number of trades-offs in the engineering choices and then decide the optimal design from a number of candidates. In order to efficiently support such decisions, we apply Model Driven Systems Engineering (MDSE), which improves the efficiency of the engineering by revealing and formalizing requirements, specifications, and designs to find a good balance among various trade-offs.
Design, fabrication, and test of a graphite/epoxy metering truss. [as applied to the LST
NASA Technical Reports Server (NTRS)
Oken, S.; Skoumal, D. E.
1975-01-01
A graphite/epoxy metering truss as applied to the large space telescope was investigated. A full-scale truss was designed, fabricated and tested. Tests included static limit loadings, a modal survey and thermal-vacuum distortion evaluation. The most critical requirement was the demonstration of the dimensional stability provided by the graphite/epoxy truss concept. Crucial to the attainment of this objective was the ability to make very sophisticated thermal growth measurements which was provided by a seven beam laser interferometer. The design of the basic truss elements were tuned to provide the high degree of dimensional stability and stiffness required by the truss. The struts and spider assembly were fabricated with Fiberite's AS/934 and HMS/934 broadgoods. The rings utilized T300 graphite fabricate with the same materials. The predicted performance of the truss was developed using the NASTRAN program. These results showed conformance with the critical stiffness and thermal distortion requirements and correlated well with the test results.
Robust fuzzy logic control of mechanical systems
NASA Astrophysics Data System (ADS)
Kohn-Rich, Sylvia
An approach for the design of robust fuzzy control laws for a large class of mechanical systems was developed. The approach applies Lyapunov's Stability Theory to ensure closed loop stability in the presence of plant perturbations and bounded disturbances. It uses inherent properties of an important class of mechanical and aerospace systems, such as robotic manipulators and large spacecraft, to derive closed-loop stability conditions. Based on these conditions, a methodology for the design of robust fuzzy control systems with guaranteed closed-loop stability was developed. Two classes of control laws for mechanical systems were considered. First, a methodology for point-to-point control was formulated. It combines an energy-type approach with Lyapunov's Stability Theory and its extensions, to obtain robust stability conditions for the closed-loop system. A procedure for control system development based on the above conditions is presented. Finally, a procedure for the implementation of the fuzzy control system with guaranteed performance and closed-loop stability characteristics is formulated. In the second part of the dissertation, the problem of robust tracking for mechanical systems was considered. Based on Lyapunov's Stability Theory and its extensions due to Leitmann and Corless, conditions were developed to prove robust stability and performance in the presence of plant uncertainties, bounded disturbances and control saturation. These conditions involve a large number of parameters and functional dependencies that can be chosen by the designer, therefore are well suited for Fuzzy Logic Control implementation. Three different fuzzy implementation methods for the proposed controls system were analyzed and their relative advantages were discussed. An extensive simulation study of the proposed approach was conducted. It demonstrated the excellent performance of the proposed control systems. The proposed method showed superior performance compared to other robust
NASA Astrophysics Data System (ADS)
Cox, Henry; Heaney, Kevin D.
2003-04-01
The term robustness in signal processing applications usually refers to approaches that are not degraded significantly when the assumptions that were invoked in defining the processing algorithm are no longer valid. Highly tuned algorithms that fall apart in real-world conditions are useless. The classic example is super-directive arrays of closely spaced elements. The very narrow beams and high directivity could be predicted under ideal conditions, could not be achieved under realistic conditions of amplitude, phase and position errors. The robust design tries to take into account the real environment as part of the optimization problem. This problem led to the introduction of the white noise gain constraint and diagonal loading in adaptive beam forming. Multiple linear constraints have been introduced in pursuit of robustness. Sonar systems such as towed arrays operate in less than ideal conditions, making robustness a concern. A special problem in sonar systems is failed array elements. This leads to severe degradation in beam patterns and bearing response patterns. Another robustness issue arises in matched field processing that uses an acoustic propagation model in the beamforming. Knowledge of the environmental parameters is usually limited. This paper reviews the various approaches to achieving robustness in sonar systems.
Applied & Computational MathematicsChallenges for the Design and Control of Dynamic Energy Systems
Brown, D L; Burns, J A; Collis, S; Grosh, J; Jacobson, C A; Johansen, H; Mezic, I; Narayanan, S; Wetter, M
2011-03-10
The Energy Independence and Security Act of 2007 (EISA) was passed with the goal 'to move the United States toward greater energy independence and security.' Energy security and independence cannot be achieved unless the United States addresses the issue of energy consumption in the building sector and significantly reduces energy consumption in buildings. Commercial and residential buildings account for approximately 40% of the U.S. energy consumption and emit 50% of CO{sub 2} emissions in the U.S. which is more than twice the total energy consumption of the entire U.S. automobile and light truck fleet. A 50%-80% improvement in building energy efficiency in both new construction and in retrofitting existing buildings could significantly reduce U.S. energy consumption and mitigate climate change. Reaching these aggressive building efficiency goals will not happen without significant Federal investments in areas of computational and mathematical sciences. Applied and computational mathematics are required to enable the development of algorithms and tools to design, control and optimize energy efficient buildings. The challenge has been issued by the U.S. Secretary of Energy, Dr. Steven Chu (emphasis added): 'We need to do more transformational research at DOE including computer design tools for commercial and residential buildings that enable reductions in energy consumption of up to 80 percent with investments that will pay for themselves in less than 10 years.' On July 8-9, 2010 a team of technical experts from industry, government and academia were assembled in Arlington, Virginia to identify the challenges associated with developing and deploying newcomputational methodologies and tools thatwill address building energy efficiency. These experts concluded that investments in fundamental applied and computational mathematics will be required to build enabling technology that can be used to realize the target of 80% reductions in energy consumption. In addition the
Guaranteed robust fault detection and isolation techniques for small satellites
NASA Astrophysics Data System (ADS)
Valavani, L.; Tantouris, N.
2013-12-01
The paper presents two generic fault detection and isolation (FDI) techniques which have shown remarkable robustness when applied to the SIMULINK model of a small satellite for thruster failures. While fundamentally different in their design approach, they both generate ʽstructured residuals' which accurately capture the failure mode. The diagnosis criterion in both methods relies on residuals direction rather than magnitude, which avoids the delays and expense of setting accurate thresholds for residuals magnitudes. Most importantly, this fact can account for the enhanced robustness to disturbances and sensor noise, as well as to significant parametric variations. Extensive Monte Carlo simulations are presented validating the robust performance of the two algorithms.
Engineering robust intelligent robots
NASA Astrophysics Data System (ADS)
Hall, E. L.; Ali, S. M. Alhaj; Ghaffari, M.; Liao, X.; Cao, M.
2010-01-01
The purpose of this paper is to discuss the challenge of engineering robust intelligent robots. Robust intelligent robots may be considered as ones that not only work in one environment but rather in all types of situations and conditions. Our past work has described sensors for intelligent robots that permit adaptation to changes in the environment. We have also described the combination of these sensors with a "creative controller" that permits adaptive critic, neural network learning, and a dynamic database that permits task selection and criteria adjustment. However, the emphasis of this paper is on engineering solutions which are designed for robust operations and worst case situations such as day night cameras or rain and snow solutions. This ideal model may be compared to various approaches that have been implemented on "production vehicles and equipment" using Ethernet, CAN Bus and JAUS architectures and to modern, embedded, mobile computing architectures. Many prototype intelligent robots have been developed and demonstrated in terms of scientific feasibility but few have reached the stage of a robust engineering solution. Continual innovation and improvement are still required. The significance of this comparison is that it provides some insights that may be useful in designing future robots for various manufacturing, medical, and defense applications where robust and reliable performance is essential.
Van Cutsem, K.; De Cock, W.; Tavernier, S.
2011-07-01
This article describes the design of a sensor interface circuit for the amplification of voltages and currents. The created PCB was tested at high temperatures and under gamma irradiation. Two different operational amplifiers were compared. (authors)
Control of HIV/AIDS infection system with drug dosages design via robust H(∞) fuzzy controller.
Assawinchaichote, Wudhichai
2015-01-01
The designing of H∞ fuzzy controller for HIV/AIDS infected dynamic system has been considered in this paper. With TS fuzzy model and LMIs approach, the proposed controller is obtained for such a system. A set of sufficient conditions of the H∞ controller is given to ensure the closed-loop system asymptotic stability and the prescribed H∞ performance level. Finally, the effectiveness of the fuzzy controller design approach is finally presented through the simulation results. PMID:26405968
Great rivers are complex, trans-border resources that are difficult to assess without bias. The U.S. EPA is using the Upper Missouri River to develop tools for biological assessments of large rivers. Our focus is to l) apply multi-density randon tessellation stratified (MD-RTS) ...
Barth, Aline Bergesch; de Oliveira, Gabriela Bolfe; Malesuik, Marcelo Donadel; Paim, Clésio Soldatelli; Volpato, Nadia Maria
2011-08-01
A stability-indicating liquid chromatography method for the determination of the antifungal agent butenafine hydrochloride (BTF) in a cream was developed and validated using the Plackett-Burman experimental design for robustness evaluation. Also, the drug photodegradation kinetics was determined. The analytical column was operated with acetonitrile, methanol and a solution of triethylamine 0.3% adjusted to pH 4.0 (6:3:1) at a flow rate of 1 mL/min and detection at 283 nm. BTF extraction from the cream was done with n-butyl alcohol and methanol in ultrasonic bath. The performed degradation conditions were: acid and basic media with HCl 1M and NaOH 1M, respectively, oxidation with H(2)O(2) 10%, and the exposure to UV-C light. No interference in the BTF elution was verified. Linearity was assessed (r(2) = 0.9999) and ANOVA showed non-significative linearity deviation (p > 0.05). Adequate results were obtained for repeatability, intra-day precision, and accuracy. Critical factors were selected to examine the method robustness with the two-level Plackett-Burman experimental design and no significant factors were detected (p > 0.05). The BTF photodegradation kinetics was determined for the standard and for the cream, both in methanolic solution, under UV light at 254 nm. The degradation process can be described by first-order kinetics in both cases. PMID:21801482
Impact of early applied upper limb stimulation: The EXPLICIT-stroke programme design
Kwakkel, Gert; Meskers, Carel GM; van Wegen, Erwin E; Lankhorst, Guus J; Geurts, Alexander CH; van Kuijk, Annet A; Lindeman, Eline; Visser-Meily, Anne; de Vlugt, Erwin; Arendzen, J Hans
2008-01-01
Background Main claims of the literature are that functional recovery of the paretic upper limb is mainly defined within the first month post stroke and that rehabilitation services should preferably be applied intensively and in a task-oriented way within this particular time window. EXplaining PLastICITy after stroke (acronym EXPLICIT-stroke) aims to explore the underlying mechanisms of post stroke upper limb recovery. Two randomized single blinded trials form the core of the programme, investigating the effects of early modified Constraint-Induced Movement Therapy (modified CIMT) and EMG-triggered Neuro-Muscular Stimulation (EMG-NMS) in patients with respectively a favourable or poor probability for recovery of dexterity. Methods/design 180 participants suffering from an acute, first-ever ischemic stroke will be recruited. Functional prognosis at the end of the first week post stroke is used to stratify patient into a poor prognosis group for upper limb recovery (N = 120, A2 project) and a group with a favourable prognosis (N = 60, A1 project). Both groups will be randomized to an experimental arm receiving respectively modified CIMT (favourable prognosis) or EMG-NMS (poor prognosis) for 3 weeks or to a control arm receiving usual care. Primary outcome variable will be the Action Research Arm Test (ARAT), assessed at 1,2,3,4,5, 8, 12 and 26 weeks post stroke. To study the impact of modified CIMT or EMG-NMS on stroke recovery mechanisms i.e. neuroplasticity, compensatory movements and upper limb neuromechanics, 60 patients randomly selected from projects A1 and A2 will undergo TMS, kinematical and haptic robotic measurements within a repeated measurement design. Additionally, 30 patients from the A1 project will undergo fMRI at baseline, 5 and 26 weeks post stroke. Conclusion EXPLICIT stroke is a 5 year translational research programme which main aim is to investigate the effects of early applied intensive intervention for regaining dexterity and to explore the
Zhu, Xiaoying; Guo, Shifeng; He, Tao; Jiang, Shan; Jańczewski, Dominik; Vancso, G Julius
2016-02-01
Cross-linked layer-by-layer (LbL) assemblies with a precisely tuned surface ζ-potential were fabricated to control the adsorption of proteins, mammalian cells, and bacteria for different biomedical applications. Two weak polyions including a synthesized polyanion and polyethylenimine were assembled under controlled conditions and cross-linked to prepare three robust LbL films as model surfaces with similar roughness and water affinity but displaying negative, zero, and positive net charges at the physiological pH (7.4). These surfaces were tested for their abilities to adsorb proteins, including bovine serum albumin (BSA) and lysozyme (LYZ). In the adsorption tests, the LbL films bind more proteins with opposite charges but less of those with like charges, indicating that electrostatic interactions play a major role in protein adsorption. However, LYZ showed higher nonspecific adsorption than BSA, because of the specific behavior of LYZ molecules, such as stacked multilayer formation during adsorption. To exclude such stacking effects from experiments, protein molecules were covalently immobilized on AFM colloidal probes to measure the adhesion forces against the model surfaces utilizing direct protein molecule-surface contacts. The results confirmed the dominating role of electrostatic forces in protein adhesion. In fibroblast cell and bacteria adhesion tests, similar trends (high adhesion on positively charged surfaces, but much lower on neutral and negatively charged surfaces) were observed because the fibroblast cell and bacterial surfaces studied possess negative potentials. The cross-linked LbL films with improved stability and engineered surface charge described in this study provide an excellent platform to control the behavior of different charged objects and can be utilized in practical biomedical applications. PMID:26756285
Code of Federal Regulations, 2012 CFR
2012-07-01
... containment building and of sufficient strength and thickness to prevent collapse under the pressure exerted... standards apply if liquids will be in my containment building? 267.1103 Section 267.1103 Protection of....1103 What additional design and operating standards apply if liquids will be in my containment...
Code of Federal Regulations, 2013 CFR
2013-07-01
... containment building and of sufficient strength and thickness to prevent collapse under the pressure exerted... standards apply if liquids will be in my containment building? 267.1103 Section 267.1103 Protection of....1103 What additional design and operating standards apply if liquids will be in my containment...
Code of Federal Regulations, 2014 CFR
2014-07-01
... containment building and of sufficient strength and thickness to prevent collapse under the pressure exerted... standards apply if liquids will be in my containment building? 267.1103 Section 267.1103 Protection of....1103 What additional design and operating standards apply if liquids will be in my containment...
Code of Federal Regulations, 2011 CFR
2011-07-01
... containment building and of sufficient strength and thickness to prevent collapse under the pressure exerted... standards apply if liquids will be in my containment building? 267.1103 Section 267.1103 Protection of....1103 What additional design and operating standards apply if liquids will be in my containment...
ERIC Educational Resources Information Center
Moxley, Roy A.
2004-01-01
R. Douglas Greer's "Designing Teaching Strategies" is an important book directed to advanced students in applied behavior analysis for classrooms. This review presents some of the striking features of the Comprehensive Applied Behavior Analysis to Schooling (CABAS[R]) program and the individualized instruction that the book advances. These include…
Applying value sensitive design (VSD) to wind turbines and wind parks: an exploration.
Oosterlaken, Ilse
2015-04-01
Community acceptance still remains a challenge for wind energy projects. The most popular explanation for local opposition, the Not in My Backyard effect, has received fierce criticism in the past decade. Critics argue that opposition is not merely a matter of selfishness or ignorance, but that moral, ecological and aesthetic values play an important role. In order to better take such values into account, a more bottom-up, participatory decision process is usually proposed. Research on this topic focusses on either stakeholder motivations/attitudes, or their behavior during project implementation. This paper proposes a third research focus, namely the 'objects' which elicit certain behavioral responses and attitudes-the wind turbine and parks. More concretely, this paper explores Value Sensitive Design (VSD) as way to arrive at wind turbines and parks that better embed or reflect key values. After a critical discussion of the notion of acceptance versus acceptability and support, the paper discusses existing literature on ecology and aesthetics in relation to wind turbine/park design, which could serve as 'building blocks' of a more integral VSD approach of the topic. It also discusses the challenge of demarcating wind park projects as VSD projects. A further challenge is that VSD has been applied mainly at the level of technical artifacts, whereas wind parks can best be conceptualized as socio-technical system. This new application would therefore expand the current practice of VSD, and may as a consequence also lead to interesting new insights for the VSD community. The paper concludes that such an outcome-oriented approach of wind turbines and park is worth exploring further, as a supplement to rather than a replacement of the process-oriented approach that is promoted by the current literature on community acceptance of wind parks. PMID:24744115
NASA Astrophysics Data System (ADS)
Mallick, Rajnish; Ganguli, Ranjan; Seetharama Bhat, M.
2015-09-01
The objective of this study is to determine an optimal trailing edge flap configuration and flap location to achieve minimum hub vibration levels and flap actuation power simultaneously. An aeroelastic analysis of a soft in-plane four-bladed rotor is performed in conjunction with optimal control. A second-order polynomial response surface based on an orthogonal array (OA) with 3-level design describes both the objectives adequately. Two new orthogonal arrays called MGB2P-OA and MGB4P-OA are proposed to generate nonlinear response surfaces with all interaction terms for two and four parameters, respectively. A multi-objective bat algorithm (MOBA) approach is used to obtain the optimal design point for the mutually conflicting objectives. MOBA is a recently developed nature-inspired metaheuristic optimization algorithm that is based on the echolocation behaviour of bats. It is found that MOBA inspired Pareto optimal trailing edge flap design reduces vibration levels by 73% and flap actuation power by 27% in comparison with the baseline design.
Case Studies for the Statistical Design of Experiments Applied to Powered Rotor Wind Tunnel Tests
NASA Technical Reports Server (NTRS)
Overmeyer, Austin D.; Tanner, Philip E.; Martin, Preston B.; Commo, Sean A.
2015-01-01
The application of statistical Design of Experiments (DOE) to helicopter wind tunnel testing was explored during two powered rotor wind tunnel entries during the summers of 2012 and 2013. These tests were performed jointly by the U.S. Army Aviation Development Directorate Joint Research Program Office and NASA Rotary Wing Project Office, currently the Revolutionary Vertical Lift Project, at NASA Langley Research Center located in Hampton, Virginia. Both entries were conducted in the 14- by 22-Foot Subsonic Tunnel with a small portion of the overall tests devoted to developing case studies of the DOE approach as it applies to powered rotor testing. A 16-47 times reduction in the number of data points required was estimated by comparing the DOE approach to conventional testing methods. The average error for the DOE surface response model for the OH-58F test was 0.95 percent and 4.06 percent for drag and download, respectively. The DOE surface response model of the Active Flow Control test captured the drag within 4.1 percent of measured data. The operational differences between the two testing approaches are identified, but did not prevent the safe operation of the powered rotor model throughout the DOE test matrices.
Applying Monte Carlo Simulation to Launch Vehicle Design and Requirements Analysis
NASA Technical Reports Server (NTRS)
Hanson, J. M.; Beard, B. B.
2010-01-01
This Technical Publication (TP) is meant to address a number of topics related to the application of Monte Carlo simulation to launch vehicle design and requirements analysis. Although the focus is on a launch vehicle application, the methods may be applied to other complex systems as well. The TP is organized so that all the important topics are covered in the main text, and detailed derivations are in the appendices. The TP first introduces Monte Carlo simulation and the major topics to be discussed, including discussion of the input distributions for Monte Carlo runs, testing the simulation, how many runs are necessary for verification of requirements, what to do if results are desired for events that happen only rarely, and postprocessing, including analyzing any failed runs, examples of useful output products, and statistical information for generating desired results from the output data. Topics in the appendices include some tables for requirements verification, derivation of the number of runs required and generation of output probabilistic data with consumer risk included, derivation of launch vehicle models to include possible variations of assembled vehicles, minimization of a consumable to achieve a two-dimensional statistical result, recontact probability during staging, ensuring duplicated Monte Carlo random variations, and importance sampling.
23 CFR 636.210 - What requirements apply to projects which use the modified design-build procedure?
Code of Federal Regulations, 2010 CFR
2010-04-01
... modified design-build procedure? 636.210 Section 636.210 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS DESIGN-BUILD CONTRACTING Selection Procedures, Award Criteria § 636.210 What requirements apply to projects which use the modified...
Code of Federal Regulations, 2014 CFR
2014-07-01
... unique snowmobile designs for small-volume manufacturers? 1051.625 Section 1051.625 Protection of... snowmobile designs for small-volume manufacturers? (a) If you are a small-volume manufacturer, we may permit... different deadlines apply to companies that are not small-volume manufacturers, do not send your...
Code of Federal Regulations, 2010 CFR
2010-07-01
... unique snowmobile designs for small-volume manufacturers? 1051.625 Section 1051.625 Protection of... snowmobile designs for small-volume manufacturers? (a) If you are a small-volume manufacturer, we may permit... different deadlines apply to companies that are not small-volume manufacturers, do not send your...
Code of Federal Regulations, 2013 CFR
2013-07-01
... unique snowmobile designs for small-volume manufacturers? 1051.625 Section 1051.625 Protection of... snowmobile designs for small-volume manufacturers? (a) If you are a small-volume manufacturer, we may permit... different deadlines apply to companies that are not small-volume manufacturers, do not send your...
23 CFR 636.210 - What requirements apply to projects which use the modified design-build procedure?
Code of Federal Regulations, 2011 CFR
2011-04-01
... modified design-build procedure? 636.210 Section 636.210 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS DESIGN-BUILD CONTRACTING Selection Procedures, Award Criteria § 636.210 What requirements apply to projects which use the modified...
Robust control of accelerators
Johnson, W.J.D. ); Abdallah, C.T. )
1990-01-01
The problem of controlling the variations in the rf power system can be effectively cast as an application of modern control theory. Two components of this theory are obtaining a model and a feedback structure. The model inaccuracies influence the choice of a particular controller structure. Because of the modeling uncertainty, one has to design either a variable, adaptive controller or a fixed, robust controller to achieve the desired objective. The adaptive control scheme usually results in very complex hardware; and, therefore, shall not be pursued in this research. In contrast, the robust control methods leads to simpler hardware. However, robust control requires a more accurate mathematical model of the physical process than is required by adaptive control. Our research at the Los Alamos National Laboratory (LANL) and the University of New Mexico (UNM) has led to the development and implementation of a new robust rf power feedback system. In this paper, we report on our research progress. In section one, the robust control problem for the rf power system and the philosophy adopted for the beginning phase of our research is presented. In section two, the results of our proof-of-principle experiments are presented. In section three, we describe the actual controller configuration that is used in LANL FEL physics experiments. The novelty of our approach is that the control hardware is implemented directly in rf without demodulating, compensating, and then remodulating.
Robust control of accelerators
NASA Astrophysics Data System (ADS)
Joel, W.; Johnson, D.; Chaouki, Abdallah T.
1991-07-01
The problem of controlling the variations in the rf power system can be effectively cast as an application of modern control theory. Two components of this theory are obtaining a model and a feedback structure. The model inaccuracies influence the choice of a particular controller structure. Because of the modelling uncertainty, one has to design either a variable, adaptive controller or a fixed, robust controller to achieve the desired objective. The adaptive control scheme usually results in very complex hardware; and, therefore, shall not be pursued in this research. In contrast, the robust control method leads to simpler hardware. However, robust control requires a more accurate mathematical model of the physical process than is required by adaptive control. Our research at the Los Alamos National Laboratory (LANL) and the University of New Mexico (UNM) has led to the development and implementation of a new robust rf power feedback system. In this article, we report on our research progress. In section 1, the robust control problem for the rf power system and the philosophy adopted for the beginning phase of our research is presented. In section 2, the results of our proof-of-principle experiments are presented. In section 3, we describe the actual controller configuration that is used in LANL FEL physics experiments. The novelty of our approach is that the control hardware is implemented directly in rf. without demodulating, compensating, and then remodulating.
Robust Understanding of Statistical Variation
ERIC Educational Resources Information Center
Peters, Susan A.
2011-01-01
This paper presents a framework that captures the complexity of reasoning about variation in ways that are indicative of robust understanding and describes reasoning as a blend of design, data-centric, and modeling perspectives. Robust understanding is indicated by integrated reasoning about variation within each perspective and across…
Robust, Optimal Subsonic Airfoil Shapes
NASA Technical Reports Server (NTRS)
Rai, Man Mohan
2014-01-01
A method has been developed to create an airfoil robust enough to operate satisfactorily in different environments. This method determines a robust, optimal, subsonic airfoil shape, beginning with an arbitrary initial airfoil shape, and imposes the necessary constraints on the design. Also, this method is flexible and extendible to a larger class of requirements and changes in constraints imposed.
Chan, Jacky Chi-Hung; Wong, Hok-Lai; Wong, Wing-Tak; Yam, Vivian Wing-Wah
2015-04-27
A series of dithienylethene-containing phosphole derivatives has been designed, synthesized and characterized. One of the compounds has been characterized by X-ray crystallography. Upon photoexcitation, the compounds exhibit drastic color changes, ascribed to the reversible photochromic behavior. Their photochromic, photophysical and electrochemical properties have been studied. They show photochromic reactivities with high photocyclization quantum yields. Their photophysical and photochromic properties are found to be facilely tuned in this system by substitution at the phosphole backbone, as well as variation on the extent of π-conjugation of the phosphole backbone. Some selected compounds have been demonstrated to exhibit photochromic properties in polymethylmethacrylate (PMMA) films. PMID:25783613
NASA Astrophysics Data System (ADS)
Usman Saeed Khan, M.; Ali, Ehsan; Maqsood, M. Irfan; Nawaz, Haq
2013-06-01
Boundary layer turbine, although invented long before but has failed to commercialize and beat the bladed turbines due to certain lacks. In this paper we have proposed and suggested some techniques to improve the design of the boundary layer turbine such that to take the optimum advantage of its efficiency, compensating all of its draw backs. A test model of proposed boundary layer turbine has been physically made and tested under different conditions. The experiments using different flow rates, different discharge rates and changing many other factors has been made and the results of these experiments are included in this paper which verifies the improvements in the output power obtained from boundary layer turbine system. This modified turbine can thus become an efficient way of producing green energy like any other renewable energy resource.
Optimization methods applied to the aerodynamic design of helicopter rotor blades
NASA Technical Reports Server (NTRS)
Walsh, Joanne L.; Bingham, Gene J.; Riley, Michael F.
1987-01-01
Described is a formal optimization procedure for helicopter rotor blade design which minimizes hover horsepower while assuring satisfactory forward flight performance. The approach is to couple hover and forward flight analysis programs with a general-purpose optimization procedure. The resulting optimization system provides a systematic evaluation of the rotor blade design variables and their interaction, thus reducing the time and cost of designing advanced rotor blades. The paper discusses the basis for and details of the overall procedure, describes the generation of advanced blade designs for representative Army helicopters, and compares design and design effort with those from the conventional approach which is based on parametric studies and extensive cross-plots.
Further Development of an Optimal Design Approach Applied to Axial Magnetic Bearings
NASA Technical Reports Server (NTRS)
Bloodgood, V. Dale, Jr.; Groom, Nelson J.; Britcher, Colin P.
2000-01-01
Classical design methods involved in magnetic bearings and magnetic suspension systems have always had their limitations. Because of this, the overall effectiveness of a design has always relied heavily on the skill and experience of the individual designer. This paper combines two approaches that have been developed to aid the accuracy and efficiency of magnetostatic design. The first approach integrates classical magnetic circuit theory with modern optimization theory to increase design efficiency. The second approach uses loss factors to increase the accuracy of classical magnetic circuit theory. As an example, an axial magnetic thrust bearing is designed for minimum power.
Petersen, Jesper; Poulsen, Lena; Petronis, Sarunas; Birgens, Henrik; Dufva, Martin
2008-01-01
DNA microarrays are generally operated at a single condition, which severely limits the freedom of designing probes for allele-specific hybridization assays. Here, we demonstrate a fluidic device for multi-stringency posthybridization washing of microarrays on microscope slides. This device is called a multi-thermal array washer (MTAW), and it has eight individually controlled heating zones, each of which corresponds to the location of a subarray on a slide. Allele-specific oligonucleotide probes for nine mutations in the beta-globin gene were spotted in eight identical subarrays at positions corresponding to the temperature zones of the MTAW. After hybridization with amplified patient material, the slides were mounted in the MTAW, and each subarray was exposed to different temperatures ranging from 22 to 40°C. When processed in the MTAW, probes selected without considering melting temperature resulted in improved genotyping compared with probes selected according to theoretical melting temperature and run under one condition. In conclusion, the MTAW is a versatile tool that can facilitate screening of a large number of probes for genotyping assays and can also enhance the performance of diagnostic arrays. PMID:18063568
NASA Astrophysics Data System (ADS)
Chou, Yu-Cheng; Lin, Po Ting
2015-10-01
The network of delivering commodities has been an important design problem in our daily lives and many transportation applications. The reliability of delivering commodities from a source node to a sink node in the network is maximised to find the optimal routing. However, the design problem is not simple due to randomly distributed attributes in each path, multiple commodities with variable path capacities and the allowable time constraints for delivery. This paper presents the design optimisation of the multi-state flow network (MSFN) for multiple commodities. We propose an efficient and robust approach to evaluate the system reliability in the MSFN with respect to randomly distributed path attributes and to find the optimal routing subject to the allowable time constraints. The delivery rates of the path segments are evaluated and the minimal-speed arcs are eliminated to reduce the complexity of the MSFN. Accordingly, the correct optimal routing is found and the worst-case reliability is evaluated. The reliability of the optimal routing is at least higher than worst-case measure. Three benchmark examples are utilised to demonstrate the proposed method. The comparisons between the original and the reduced networks show that the proposed method is very efficient.
Hybrid inversions of CO2 fluxes at regional scale applied to network design
NASA Astrophysics Data System (ADS)
Kountouris, Panagiotis; Gerbig, Christoph; -Thomas Koch, Frank
2013-04-01
Long term observations of atmospheric greenhouse gas measuring stations, located at representative regions over the continent, improve our understanding of greenhouse gas sources and sinks. These mixing ratio measurements can be linked to surface fluxes by atmospheric transport inversions. Within the upcoming years new stations are to be deployed, which requires decision making tools with respect to the location and the density of the network. We are developing a method to assess potential greenhouse gas observing networks in terms of their ability to recover specific target quantities. As target quantities we use CO2 fluxes aggregated to specific spatial and temporal scales. We introduce a high resolution inverse modeling framework, which attempts to combine advantages from pixel based inversions with those of a carbon cycle data assimilation system (CCDAS). The hybrid inversion system consists of the Lagrangian transport model STILT, the diagnostic biosphere model VPRM and a Bayesian inversion scheme. We aim to retrieve the spatiotemporal distribution of net ecosystem exchange (NEE) at a high spatial resolution (10 km x 10 km) by inverting for spatially and temporally varying scaling factors for gross ecosystem exchange (GEE) and respiration (R) rather than solving for the fluxes themselves. Thus the state space includes parameters for controlling photosynthesis and respiration, but unlike in a CCDAS it allows for spatial and temporal variations, which can be expressed as NEE(x,y,t) = λG(x,y,t) GEE(x,y,t) + λR(x,y,t) R(x,y,t) . We apply spatially and temporally correlated uncertainties by using error covariance matrices with non-zero off-diagonal elements. Synthetic experiments will test our system and select the optimal a priori error covariance by using different spatial and temporal correlation lengths on the error statistics of the a priori covariance and comparing the optimized fluxes against the 'known truth'. As 'known truth' we use independent fluxes
Development of direct-inverse 3-D methods for applied transonic aerodynamic wing design and analysis
NASA Technical Reports Server (NTRS)
Carlson, Leland A.
1989-01-01
Progress in the direct-inverse wing design method in curvilinear coordinates has been made. This includes the remedying of a spanwise oscillation problem and the assessment of grid skewness, viscous interaction, and the initial airfoil section on the final design. It was found that, in response to the spanwise oscillation problem that designing at every other spanwise station produced the best results for the cases presented, a smoothly varying grid is especially needed for the accurate design at the wing tip, the boundary layer displacement thicknesses must be included in a successful wing design, the design of high and medium aspect ratio wings is possible with this code, and the final airfoil section designed is fairly independent of the initial section.
NASA Astrophysics Data System (ADS)
Valentic, T. A.
2012-12-01
The Data Transport Network is designed for the delivery of data from scientific instruments located at remote field sites with limited or unreliable communications. Originally deployed at the Sondrestrom Research Facility in Greenland over a decade ago, the system supports the real-time collection and processing of data from large instruments such as incoherent scatter radars and lidars. In recent years, the Data Transport Network has been adapted to small, low-power embedded systems controlling remote instrumentation platforms deployed throughout the Arctic. These projects include multiple buoys from the O-Buoy, IceLander and IceGoat programs, renewable energy monitoring at the Imnavait Creek and Ivotuk field sites in Alaska and remote weather observation stations in Alaska and Greenland. This presentation will discuss the common communications controller developed for these projects. Although varied in their application, each of these systems share a number of common features. Multiple instruments are attached, each of which needs to be power controlled, data sampled and files transmitted offsite. In addition, the power usage of the overall system must be minimized to handle the limited energy available from sources such as solar, wind and fuel cells. The communications links are satellite based. The buoys and weather stations utilize Iridium, necessitating the need to handle the common drop outs and high-latency, low-bandwidth nature of the link. The communications controller is an off-the-shelf, low-power, single board computer running a customized version of the Linux operating system. The Data Transport Network provides a Python-based software framework for writing individual data collection programs and supplies a number of common services for configuration, scheduling, logging, data transmission and resource management. Adding a new instrument involves writing only the necessary code for interfacing to the hardware. Individual programs communicate with the
NASA Astrophysics Data System (ADS)
Haag, D.; Auweter-Kurtz, M.; Fertig, M.
2004-10-01
In this paper, the plasma flow in applied field magneto-plasmadynamic (AFMPD) thrusters is described by conservation equations for heavy particles, electrons and the magnetic field for thermal and chemical non-equilibrium. To take into account the effects of the applied magnetic field a quasi-three dimensional approach with vanishing azimuthal derivatives is used for the velocity and magnetic field. The vector potential formulation has been chosen for the description of the applied magnetic field to handle the influences of solenoidal coils and induced azimuthal current density on the magnetic field. The numerical scheme is based on a two-dimensional, axisymmetric finite volume method on unstructured, adaptive meshes.
Demonstration of structural optimization applied to wind-tunnel model design
NASA Astrophysics Data System (ADS)
French, Mark; Kolonay, Raymond M.
1992-10-01
Results are presented which indicate that using structural optimization to design wind-tunnel models can result in a procedure that matches design stiffnesses well enough to be very useful in sizing the structures of aeroelastic models. The design procedure that is presented demonstrates that optimization can be useful in the design of aeroelastically scaled wind-tunnel models. The resulting structure effectively models an aeroelastically tailored composite wing with a simple aluminum beam structure, a structure that should be inexpensive to manufacture compared with a composite one.
Robustness of spatial micronetworks
NASA Astrophysics Data System (ADS)
McAndrew, Thomas C.; Danforth, Christopher M.; Bagrow, James P.
2015-04-01
Power lines, roadways, pipelines, and other physical infrastructure are critical to modern society. These structures may be viewed as spatial networks where geographic distances play a role in the functionality and construction cost of links. Traditionally, studies of network robustness have primarily considered the connectedness of large, random networks. Yet for spatial infrastructure, physical distances must also play a role in network robustness. Understanding the robustness of small spatial networks is particularly important with the increasing interest in microgrids, i.e., small-area distributed power grids that are well suited to using renewable energy resources. We study the random failures of links in small networks where functionality depends on both spatial distance and topological connectedness. By introducing a percolation model where the failure of each link is proportional to its spatial length, we find that when failures depend on spatial distances, networks are more fragile than expected. Accounting for spatial effects in both construction and robustness is important for designing efficient microgrids and other network infrastructure.
Robustness of spatial micronetworks.
McAndrew, Thomas C; Danforth, Christopher M; Bagrow, James P
2015-04-01
Power lines, roadways, pipelines, and other physical infrastructure are critical to modern society. These structures may be viewed as spatial networks where geographic distances play a role in the functionality and construction cost of links. Traditionally, studies of network robustness have primarily considered the connectedness of large, random networks. Yet for spatial infrastructure, physical distances must also play a role in network robustness. Understanding the robustness of small spatial networks is particularly important with the increasing interest in microgrids, i.e., small-area distributed power grids that are well suited to using renewable energy resources. We study the random failures of links in small networks where functionality depends on both spatial distance and topological connectedness. By introducing a percolation model where the failure of each link is proportional to its spatial length, we find that when failures depend on spatial distances, networks are more fragile than expected. Accounting for spatial effects in both construction and robustness is important for designing efficient microgrids and other network infrastructure. PMID:25974553
NASA Technical Reports Server (NTRS)
Munoz Fernandez, Michela Miche
2014-01-01
The potential of Model Model Systems Engineering (MBSE) using the Architecture Analysis and Design Language (AADL) applied to space systems will be described. AADL modeling is applicable to real-time embedded systems- the types of systems NASA builds. A case study with the Juno mission to Jupiter showcases how this work would enable future missions to benefit from using these models throughout their life cycle from design to flight operations.
34 CFR 370.44 - What reporting requirement applies to each designated agency?
Code of Federal Regulations, 2010 CFR
2010-07-01
... reason or reasons for those referrals; (c) The number of requests for advocacy services received by the designated agency from clients or client applicants; (d) The number of the requests for advocacy services... the designated agency was unable to serve all of the requests for advocacy services from clients...
34 CFR 370.44 - What reporting requirement applies to each designated agency?
Code of Federal Regulations, 2011 CFR
2011-07-01
... reason or reasons for those referrals; (c) The number of requests for advocacy services received by the designated agency from clients or client applicants; (d) The number of the requests for advocacy services... the designated agency was unable to serve all of the requests for advocacy services from clients...
ERIC Educational Resources Information Center
Linder, Kathryn E.; Cooper, Frank Rudy; McKenzie, Elizabeth M.; Raesch, Monika; Reeve, Patricia A.
2014-01-01
Backward design is a course creation method that encourages teachers to identify their goals for student understanding and measurable objectives for learning from the outset. In this article we explore the application of backward design to the production of scholarly articles. Specifically, we report on a writing group program that encourages…
Interview with Charles M. Reigeluth: Applying Instructional Design to Educational Reform
ERIC Educational Resources Information Center
Simsek, Ali
2013-01-01
Charles M. Reigeluth is one of the most contributing and certainly the leading scholars in the field of educational technology and instructional design. His early contributions were about developing instructional design theories such as Elaboration Theory and Component Display Theory. He has also edited monumental books as collections of major ID…
Applying a Competency- and Problem-Based Approach for Learning Compiler Design
ERIC Educational Resources Information Center
Khoumsi, Ahmed; Gonzalez-Rubio, Ruben
2006-01-01
Our department has redesigned its electrical engineering and computer engineering programs completely by adopting a learning methodology based on competence development, problem solving, and the realization of design projects. In this article, we show how this pedagogical approach has been successfully used for learning compiler design.
Development of direct-inverse 3-D methods for applied transonic aerodynamic wing design and analysis
NASA Technical Reports Server (NTRS)
Carlson, Leland A.
1989-01-01
An inverse wing design method was developed around an existing transonic wing analysis code. The original analysis code, TAWFIVE, has as its core the numerical potential flow solver, FLO30, developed by Jameson and Caughey. Features of the analysis code include a finite-volume formulation; wing and fuselage fitted, curvilinear grid mesh; and a viscous boundary layer correction that also accounts for viscous wake thickness and curvature. The development of the inverse methods as an extension of previous methods existing for design in Cartesian coordinates is presented. Results are shown for inviscid wing design cases in super-critical flow regimes. The test cases selected also demonstrate the versatility of the design method in designing an entire wing or discontinuous sections of a wing.
NASA Astrophysics Data System (ADS)
Rider, William; Witkowski, Walt; Kamm, James R.; Wildey, Tim
2016-02-01
We introduce a new methodology for inferring the accuracy of computational simulations through the practice of solution verification. We demonstrate this methodology on examples from computational heat transfer, fluid dynamics and radiation transport. Our methodology is suited to both well- and ill-behaved sequences of simulations. Our approach to the analysis of these sequences of simulations incorporates expert judgment into the process directly via a flexible optimization framework, and the application of robust statistics. The expert judgment is systematically applied as constraints to the analysis, and together with the robust statistics guards against over-emphasis on anomalous analysis results. We have named our methodology Robust Verification. Our methodology is based on utilizing multiple constrained optimization problems to solve the verification model in a manner that varies the analysis' underlying assumptions. Constraints applied in the analysis can include expert judgment regarding convergence rates (bounds and expectations) as well as bounding values for physical quantities (e.g., positivity of energy or density). This approach then produces a number of error models, which are then analyzed through robust statistical techniques (median instead of mean statistics). This provides self-contained, data and expert informed error estimation including uncertainties for both the solution itself and order of convergence. Our method produces high quality results for the well-behaved cases relatively consistent with existing practice. The methodology can also produce reliable results for ill-behaved circumstances predicated on appropriate expert judgment. We demonstrate the method and compare the results with standard approaches used for both code and solution verification on well-behaved and ill-behaved simulations.
ERIC Educational Resources Information Center
Conole, Grainne; Culver, Juliette
2010-01-01
This paper describes a new social networking site, Cloudworks, which aims to provide a dynamic environment for finding, sharing and discussing learning and teaching ideas and designs. The paper begins by discussing the mismatch between the potential application of technologies in education and their actual use in practice. It considers some of the…
NASA Technical Reports Server (NTRS)
Driggs, Ivan H
1925-01-01
T.M. 311 gave a short outline of modern theoretical aerodynamics as applied to light airplane design. This discussion may have been somewhat obscure to the nontechnical reader. A series of charts or curves should serve to clear up such obscurity as well as to more definitely emphasize those quantities most important for each flight characteristic.
Code of Federal Regulations, 2013 CFR
2013-07-01
... and Construction Sustainable Development § 102-76.55 What sustainable development principles must... Acquisition,” Federal agencies must apply sustainable development principles to the siting, design, and... 41 Public Contracts and Property Management 3 2013-07-01 2013-07-01 false What...
Code of Federal Regulations, 2010 CFR
2010-07-01
... and Construction Sustainable Development § 102-76.55 What sustainable development principles must... Acquisition,” Federal agencies must apply sustainable development principles to the siting, design, and... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false What...
Code of Federal Regulations, 2012 CFR
2012-01-01
... and Construction Sustainable Development § 102-76.55 What sustainable development principles must... Acquisition,” Federal agencies must apply sustainable development principles to the siting, design, and... 41 Public Contracts and Property Management 3 2012-01-01 2012-01-01 false What...
Code of Federal Regulations, 2014 CFR
2014-01-01
... and Construction Sustainable Development § 102-76.55 What sustainable development principles must... Acquisition,” Federal agencies must apply sustainable development principles to the siting, design, and... 41 Public Contracts and Property Management 3 2014-01-01 2014-01-01 false What...
Code of Federal Regulations, 2011 CFR
2011-01-01
... 41 Public Contracts and Property Management 3 2011-01-01 2011-01-01 false What sustainable development principles must Federal agencies apply to the siting, design, and construction of new facilities? 102-76.55 Section 102-76.55 Public Contracts and Property Management Federal Property Management Regulations System (Continued) FEDERAL...
34 CFR 370.41 - What conflict of interest provision applies to employees of a designated agency?
Code of Federal Regulations, 2011 CFR
2011-07-01
... 34 Education 2 2011-07-01 2010-07-01 true What conflict of interest provision applies to employees of a designated agency? 370.41 Section 370.41 Education Regulations of the Offices of the Department of Education (Continued) OFFICE OF SPECIAL EDUCATION AND REHABILITATIVE SERVICES, DEPARTMENT...
34 CFR 370.41 - What conflict of interest provision applies to employees of a designated agency?
Code of Federal Regulations, 2010 CFR
2010-07-01
... 34 Education 2 2010-07-01 2010-07-01 false What conflict of interest provision applies to employees of a designated agency? 370.41 Section 370.41 Education Regulations of the Offices of the Department of Education (Continued) OFFICE OF SPECIAL EDUCATION AND REHABILITATIVE SERVICES, DEPARTMENT...
Code of Federal Regulations, 2011 CFR
2011-01-01
... 41 Public Contracts and Property Management 3 2011-01-01 2011-01-01 false Do the Interagency Security Committee Security Design Criteria apply to all new Federally owned and leased facilities? 102-81.25 Section 102-81.25 Public Contracts and Property Management Federal Property Management Regulations System (Continued) FEDERAL...
A General Multidisciplinary Turbomachinery Design Optimization system Applied to a Transonic Fan
NASA Astrophysics Data System (ADS)
Nemnem, Ahmed Mohamed Farid
The blade geometry design process is integral to the development and advancement of compressors and turbines in gas generators or aeroengines. A new airfoil section design capability has been added to an open source parametric 3D blade design tool. Curvature of the meanline is controlled using B-splines to create the airfoils. The curvature is analytically integrated to derive the angles and the meanline is obtained by integrating the angles. A smooth thickness distribution is then added to the airfoil to guarantee a smooth shape while maintaining a prescribed thickness distribution. A leading edge B-spline definition has also been implemented to achieve customized airfoil leading edges which guarantees smoothness with parametric eccentricity and droop. An automated turbomachinery design and optimization system has been created. An existing splittered transonic fan is used as a test and reference case. This design was more general than a conventional design to have access to the other design methodology. The whole mechanical and aerodynamic design loops are automated for the optimization process. The flow path and the geometrical properties of the rotor are initially created using the axi-symmetric design and analysis code (T-AXI). The main and splitter blades are parametrically designed with the created geometry builder (3DBGB) using the new added features (curvature technique). The solid model creation of the rotor sector with a periodic boundaries combining the main blade and splitter is done using MATLAB code directly connected to SolidWorks including the hub, fillets and tip clearance. A mechanical optimization is performed with DAKOTA (developed by DOE) to reduce the mass of the blades while keeping maximum stress as a constraint with a safety factor. A Genetic algorithm followed by Numerical Gradient optimization strategies are used in the mechanical optimization. The splittered transonic fan blades mass is reduced by 2.6% while constraining the maximum
Development of direct-inverse 3-D methods for applied aerodynamic design and analysis
NASA Technical Reports Server (NTRS)
Carlson, Leland A.
1988-01-01
Several inverse methods have been compared and initial results indicate that differences in results are primarily due to coordinate systems and fuselage representations and not to design procedures. Further, results from a direct-inverse method that includes 3-D wing boundary layer effects, wake curvature, and wake displacement are presented. These results show that boundary layer displacements must be included in the design process for accurate results.
Design of robust systolic algorithms
Varman, P.J.; Fussell, D.S.
1983-01-01
A primary reason for the susceptibility of systolic algorithms to faults is their strong dependence on the interconnection between the processors in a systolic array. A technique to transform any linear systolic algorithm into an equivalent pipelined algorithm that executes on arbitrary trees is presented. 5 references.
Applying CBR to machine tool product configuration design oriented to customer requirements
NASA Astrophysics Data System (ADS)
Wang, Pengjia; Gong, Yadong; Xie, Hualong; Liu, Yongxian; Nee, Andrew Yehching
2016-03-01
Product customization is a trend in the current market-oriented manufacturing environment. However, deduction from customer requirements to design results and evaluation of design alternatives are still heavily reliant on the designer's experience and knowledge. To solve the problem of fuzziness and uncertainty of customer requirements in product configuration, an analysis method based on the grey rough model is presented. The customer requirements can be converted into technical characteristics effectively. In addition, an optimization decision model for product planning is established to help the enterprises select the key technical characteristics under the constraints of cost and time to serve the customer to maximal satisfaction. A new case retrieval approach that combines the self-organizing map and fuzzy similarity priority ratio method is proposed in case-based design. The self-organizing map can reduce the retrieval range and increase the retrieval efficiency, and the fuzzy similarity priority ratio method can evaluate the similarity of cases comprehensively. To ensure that the final case has the best overall performance, an evaluation method of similar cases based on grey correlation analysis is proposed to evaluate similar cases to select the most suitable case. Furthermore, a computer-aided system is developed using MATLAB GUI to assist the product configuration design. The actual example and result on an ETC series machine tool product show that the proposed method is effective, rapid and accurate in the process of product configuration. The proposed methodology provides a detailed instruction for the product configuration design oriented to customer requirements.
Robust impedance shaping telemanipulation
Colgate, J.E.
1993-08-01
When a human operator performs a task via a bilateral manipulator, the feel of the task is embodied in the mechanical impedance of the manipulator. Traditionally, a bilateral manipulator is designed for transparency; i.e., so that the impedance reflected through the manipulator closely approximates that of the task. Impedance shaping bilateral control, introduced here, differs in that it treats the bilateral manipulator as a means of constructively altering the impedance of a task. This concept is particularly valuable if the characteristic dimensions (e.g., force, length, time) of the task impedance are very different from those of the human limb. It is shown that a general form of impedance shaping control consists of a conventional power-scaling bilateral controller augmented with a real-time interactive task simulation (i.e., a virtual environment). An approach to impedance shaping based on kinematic similarity between tasks of different scale is introduced and illustrated with an example. It is shown that an important consideration in impedance shaping controller design is robustness; i.e., guaranteeing the stability of the operator/manipulator/task system. A general condition for the robustness of a bilateral manipulator is derived. This condition is based on the structured singular value ({mu}). An example of robust impedance shaping bilateral control is presented and discussed.
Robust Fixed-Structure Controller Synthesis
NASA Technical Reports Server (NTRS)
Corrado, Joseph R.; Haddad, Wassim M.; Gupta, Kajal (Technical Monitor)
2000-01-01
The ability to develop an integrated control system design methodology for robust high performance controllers satisfying multiple design criteria and real world hardware constraints constitutes a challenging task. The increasingly stringent performance specifications required for controlling such systems necessitates a trade-off between controller complexity and robustness. The principle challenge of the minimal complexity robust control design is to arrive at a tractable control design formulation in spite of the extreme complexity of such systems. Hence, design of minimal complexitY robust controllers for systems in the face of modeling errors has been a major preoccupation of system and control theorists and practitioners for the past several decades.
A Picture Is Worth a Thousand Words: Applying Image-Based Learning to Course Design
ERIC Educational Resources Information Center
Whitley, Cameron T.
2013-01-01
Although images are often used in the classroom to communicate difficult concepts, students have little input into their selection and application. This approach can create a passive experience for students and represents a missed opportunity for instructors to engage participation. By applying concepts found in visual sociology to techniques…
Comparative Case Study on Designing and Applying Flipped Classroom at Universities
ERIC Educational Resources Information Center
Lim, Cheolil; Kim, Sunyoung; Lee, Jihyun; Kim, Hyeonsu; Han, Hyeongjong
2014-01-01
There have been many reports on cases where flipped classroom was applied which put greater emphasis on conducting various learning activities during class. However, there is a limitation in redesigning existing university lectures as flipped classrooms merely based on reports that describe the learning activities of and their effects on…