Variational Methods in Design Optimization and Sensitivity Analysis for Two-Dimensional Euler Equations

NASA Technical Reports Server (NTRS)

Ibrahim, A. H.; Tiwari, S. N.; Smith, R. E.

1997-01-01

Variational methods (VM) sensitivity analysis employed to derive the costate (adjoint) equations, the transversality conditions, and the functional sensitivity derivatives. In the derivation of the sensitivity equations, the variational methods use the generalized calculus of variations, in which the variable boundary is considered as the design function. The converged solution of the state equations together with the converged solution of the costate equations are integrated along the domain boundary to uniquely determine the functional sensitivity derivatives with respect to the design function. The application of the variational methods to aerodynamic shape optimization problems is demonstrated for internal flow problems at supersonic Mach number range. The study shows, that while maintaining the accuracy of the functional sensitivity derivatives within the reasonable range for engineering prediction purposes, the variational methods show a substantial gain in computational efficiency, i.e., computer time and memory, when compared with the finite difference sensitivity analysis.

Behavior sensitivities for control augmented structures

NASA Technical Reports Server (NTRS)

Manning, R. A.; Lust, R. V.; Schmit, L. A.

1987-01-01

During the past few years it has been recognized that combining passive structural design methods with active control techniques offers the prospect of being able to find substantially improved designs. These developments have stimulated interest in augmenting structural synthesis by adding active control system design variables to those usually considered in structural optimization. An essential step in extending the approximation concepts approach to control augmented structural synthesis is the development of a behavior sensitivity analysis capability for determining rates of change of dynamic response quantities with respect to changes in structural and control system design variables. Behavior sensitivity information is also useful for man-machine interactive design as well as in the context of system identification studies. Behavior sensitivity formulations for both steady state and transient response are presented and the quality of the resulting derivative information is evaluated.

Integrating ethics in design through the value-sensitive design approach.

PubMed

Cummings, Mary L

2006-10-01

The Accreditation Board of Engineering and Technology (ABET) has declared that to achieve accredited status, 'engineering programs must demonstrate that their graduates have an understanding of professional and ethical responsibility.' Many engineering professors struggle to integrate this required ethics instruction in technical classes and projects because of the lack of a formalized ethics-in-design approach. However, one methodology developed in human-computer interaction research, the Value-Sensitive Design approach, can serve as an engineering education tool which bridges the gap between design and ethics for many engineering disciplines. The three major components of Value-Sensitive Design, conceptual, technical, and empirical, exemplified through a case study which focuses on the development of a command and control supervisory interface for a military cruise missile.

Automated Sensitivity Analysis of Interplanetary Trajectories for Optimal Mission Design

NASA Technical Reports Server (NTRS)

Knittel, Jeremy; Hughes, Kyle; Englander, Jacob; Sarli, Bruno

2017-01-01

This work describes a suite of Python tools known as the Python EMTG Automated Trade Study Application (PEATSA). PEATSA was written to automate the operation of trajectory optimization software, simplify the process of performing sensitivity analysis, and was ultimately found to out-perform a human trajectory designer in unexpected ways. These benefits will be discussed and demonstrated on sample mission designs.

A NEW HOUSE DUST COLLECTION SYSTEM AND ITS USE IN A STUDY OF ASTHMA IN DUST MITE SENSITIVE CHILDREN IN RALEIGH, NORTH CAROLINA

EPA Science Inventory

A prototype dust collection system, the House Dust Vacuum One (HDVI), was designed for use in a study to investigate the relationship between house dust mite antigen levels and the presence of asthma in dust mite sensitive children. The HDVI was designed for the collection of dus...

Theoretical studies on effective metal-to-ligand charge transfer characteristics of novel ruthenium dyes for dye sensitized solar cells.

PubMed

Wang, Huei-Tang; Taufany, Fadlilatul; Nachimuthu, Santhanamoorthi; Jiang, Jyh-Chiang

2014-05-01

The development of ruthenium dye-sensitizers with highly effective metal-to-ligand charge transfer (MLCT) characteristics and narrowed transition energy gaps are essential for the new generation of dye-sensitized solar cells. Here, we designed a novel anchoring ligand by inserting the cyanovinyl-branches inside the anchoring ligands of selected highly efficient dye-sensitizers and studied their intrinsic optical properties using theoretical methods. Our calculated results show that the designed ruthenium dyes provide good performances as sensitizers compared to the selected efficient dyes, because of their red-shift in the UV-visible absorption spectra with an increase in the absorption intensity, smaller energy gaps and thereby enhancing MLCT transitions. We found that, the designed anchoring ligand acts as an efficient "electron-acceptor" which boosts electron-transfer from a -NCS ligand to this ligand via a Ru-bridge, thus providing a way to lower the transition energy gap and enhance the MLCT transitions.

AASHTO mechanistic-empirical pavement design guide parametric study.

DOT National Transportation Integrated Search

2012-03-01

This study focuses on assessing the robustness of the AASHTO Mechanistic-Empirical Pavement Design Guide (MEPDG v 1.1) for rigid pavement : design projects in Wisconsin. The primary tasks conducted in this study included performing sensitivity analys...

Optimization of PET instrumentation for brain activation studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dahlbom, M.; Cherry, S.R.; Hoffman, E.J.

By performing cerebral blood flow studies with positron emission tomography (PET), and comparing blood flow images of different states of activation, functional mapping of the brain is possible. The ability of current commercial instruments to perform such studies is investigated in this work, based on a comparison of noise equivalent count (NEC) rates. Differences in the NEC performance of the different scanners in conjunction with scanner design parameters, provide insights into the importance of block design (size, dead time, crystal thickness) and overall scanner design (sensitivity and scatter fraction) for optimizing data from activation studies. The newer scanners with removablemore » septa, operating with 3-D acquisition, have much higher sensitivity, but require new methodology for optimized operation. Only by administering multiple low doses (fractionation) of the flow tracer can the high sensitivity be utilized.« less

A before-and-after study of traffic conflicts at the U.S. Route One entrance to Camden Hills State Park : an evaluation of a portion of a context sensitive design project.

DOT National Transportation Integrated Search

2007-09-01

Route 1 has been reconstructed as a Context Sensitive Design Project in the Camden, : Maine area. The purpose of this study is to evaluate the safety effect of the reconstruction of the highway at the entrances to the Camden Hills State Park. The two...

Design principles for enhancing phase sensitivity and suppressing phase fluctuations simultaneously in biochemical oscillatory systems.

PubMed

Fei, Chenyi; Cao, Yuansheng; Ouyang, Qi; Tu, Yuhai

2018-04-12

Biological systems need to function accurately in the presence of strong noise and at the same time respond sensitively to subtle external cues. Here we study design principles in biochemical oscillatory circuits to achieve these two seemingly incompatible goals. We show that energy dissipation can enhance phase sensitivity linearly by driving the phase-amplitude coupling and increase timing accuracy by suppressing phase diffusion. Two general design principles in the key underlying reaction loop formed by two antiparallel pathways are found to optimize oscillation performance with a given energy budget: balancing the forward-to-backward flux ratio between the two pathways to reduce phase diffusion and maximizing the net flux of the phase-advancing pathway relative to that of the phase-retreating pathway to enhance phase sensitivity. Experimental evidences consistent with these design principles are found in the circadian clock of cyanobacteria. Future experiments to test the predicted dependence of phase sensitivity on energy dissipation are proposed.

Human Mars Ascent Vehicle Performance Sensitivities

NASA Technical Reports Server (NTRS)

Polsgrove, Tara P.; Thomas, Herbert D.

2016-01-01

Human Mars mission architecture studies have shown that the ascent vehicle mass drives performance requirements for the descent and in-space transportation elements. Understanding the sensitivity of Mars ascent vehicle (MAV) mass to various mission and vehicle design choices enables overall transportation system optimization. This paper presents the results of a variety of sensitivity trades affecting MAV performance including: landing site latitude, target orbit, initial thrust to weight ratio, staging options, specific impulse, propellant type and engine design.

The New Suburb -- Guidelines for Transit Sensitive Suburban Land Use Design: Study of Land Use and Transportation in the Suburbs - Report Two

DOT National Transportation Integrated Search

1991-07-01

This report provides guidelines for the planning and design of land use patterns that are sensitive to the needs of public transit. These guidelines are meant to create an efficient environment for future growth in suburban areas. The guidelines have...

Continuous coaxial cable sensors for monitoring of RC structures with electrical time domain reflectometry

NASA Astrophysics Data System (ADS)

Chen, Genda; Mu, Huimin; Pommerenke, David; Drewniak, James L.

2003-08-01

This study was aimed at developing and validating a new type of coaxial cable sensors that can be used to detect cracks or measure strains in reinforced concrete (RC) structures. The new sensors were designed based on the change in outer conductor configuration under strain effects in contrast to the geometry-based design in conventional coaxial cable sensors. Both numerical simulations and calibration tests with strain gauges of a specific design of the proposed cables were conducted to study the cables' sensitivity. Four designs of the proposed type of sensors were then respectively mounted near the surface of six 3-foot-long RC beams. They were tested in bending to further validate the cables' sensitivity in concrete members. The calibration test results generally agree with the numerical simulations. They showed that the proposed sensors are over 10~50 times more sensitive than conventional cable sensors. The test results of the beams not only validate the sensitivity of the new sensors but also indicate a good correlation with the measured crack width.

Behavior of sensitivities in the one-dimensional advection-dispersion equation: Implications for parameter estimation and sampling design

USGS Publications Warehouse

Knopman, Debra S.; Voss, Clifford I.

1987-01-01

The spatial and temporal variability of sensitivities has a significant impact on parameter estimation and sampling design for studies of solute transport in porous media. Physical insight into the behavior of sensitivities is offered through an analysis of analytically derived sensitivities for the one-dimensional form of the advection-dispersion equation. When parameters are estimated in regression models of one-dimensional transport, the spatial and temporal variability in sensitivities influences variance and covariance of parameter estimates. Several principles account for the observed influence of sensitivities on parameter uncertainty. (1) Information about a physical parameter may be most accurately gained at points in space and time with a high sensitivity to the parameter. (2) As the distance of observation points from the upstream boundary increases, maximum sensitivity to velocity during passage of the solute front increases and the consequent estimate of velocity tends to have lower variance. (3) The frequency of sampling must be “in phase” with the S shape of the dispersion sensitivity curve to yield the most information on dispersion. (4) The sensitivity to the dispersion coefficient is usually at least an order of magnitude less than the sensitivity to velocity. (5) The assumed probability distribution of random error in observations of solute concentration determines the form of the sensitivities. (6) If variance in random error in observations is large, trends in sensitivities of observation points may be obscured by noise and thus have limited value in predicting variance in parameter estimates among designs. (7) Designs that minimize the variance of one parameter may not necessarily minimize the variance of other parameters. (8) The time and space interval over which an observation point is sensitive to a given parameter depends on the actual values of the parameters in the underlying physical system.

Design and characterization of planar capacitive imaging probe based on the measurement sensitivity distribution

NASA Astrophysics Data System (ADS)

Yin, X.; Chen, G.; Li, W.; Huthchins, D. A.

2013-01-01

Previous work indicated that the capacitive imaging (CI) technique is a useful NDE tool which can be used on a wide range of materials, including metals, glass/carbon fibre composite materials and concrete. The imaging performance of the CI technique for a given application is determined by design parameters and characteristics of the CI probe. In this paper, a rapid method for calculating the whole probe sensitivity distribution based on the finite element model (FEM) is presented to provide a direct view of the imaging capabilities of the planar CI probe. Sensitivity distributions of CI probes with different geometries were obtained. Influencing factors on sensitivity distribution were studied. Comparisons between CI probes with point-to-point triangular electrode pair and back-to-back triangular electrode pair were made based on the analysis of the corresponding sensitivity distributions. The results indicated that the sensitivity distribution could be useful for optimising the probe design parameters and predicting the imaging performance.

Dynamic Compression of the Signal in a Charge Sensitive Amplifier: From Concept to Design

NASA Astrophysics Data System (ADS)

Manghisoni, Massimo; Comotti, Daniele; Gaioni, Luigi; Ratti, Lodovico; Re, Valerio

2015-10-01

This work is concerned with the design of a low-noise Charge Sensitive Amplifier featuring a dynamic signal compression based on the non-linear features of an inversion-mode MOS capacitor. These features make the device suitable for applications where a non-linear characteristic of the front-end is required, such as in imaging instrumentation for free electron laser experiments. The aim of the paper is to discuss a methodology for the proper design of the feedback network enabling the dynamic signal compression. Starting from this compression solution, the design of a low-noise Charge Sensitive Amplifier is also discussed. The study has been carried out by referring to a 65 nm CMOS technology.

High-Sensitivity GaN Microchemical Sensors

NASA Technical Reports Server (NTRS)

Son, Kyung-ah; Yang, Baohua; Liao, Anna; Moon, Jeongsun; Prokopuk, Nicholas

2009-01-01

Systematic studies have been performed on the sensitivity of GaN HEMT (high electron mobility transistor) sensors using various gate electrode designs and operational parameters. The results here show that a higher sensitivity can be achieved with a larger W/L ratio (W = gate width, L = gate length) at a given D (D = source-drain distance), and multi-finger gate electrodes offer a higher sensitivity than a one-finger gate electrode. In terms of operating conditions, sensor sensitivity is strongly dependent on transconductance of the sensor. The highest sensitivity can be achieved at the gate voltage where the slope of the transconductance curve is the largest. This work provides critical information about how the gate electrode of a GaN HEMT, which has been identified as the most sensitive among GaN microsensors, needs to be designed, and what operation parameters should be used for high sensitivity detection.

Automated Sensitivity Analysis of Interplanetary Trajectories

NASA Technical Reports Server (NTRS)

Knittel, Jeremy; Hughes, Kyle; Englander, Jacob; Sarli, Bruno

2017-01-01

This work describes a suite of Python tools known as the Python EMTG Automated Trade Study Application (PEATSA). PEATSA was written to automate the operation of trajectory optimization software, simplify the process of performing sensitivity analysis, and was ultimately found to out-perform a human trajectory designer in unexpected ways. These benefits will be discussed and demonstrated on sample mission designs.

Preparation of the implementation plan of AASHTO Mechanistic-Empirical Pavement Design Guide (M-EPDG) in Connecticut : Phase II : expanded sensitivity analysis and validation with pavement management data.

DOT National Transportation Integrated Search

2017-02-08

The study re-evaluates distress prediction models using the Mechanistic-Empirical Pavement Design Guide (MEPDG) and expands the sensitivity analysis to a wide range of pavement structures and soils. In addition, an extensive validation analysis of th...

Selective Intercultural Sensitivity to Different Sources of Cultural Identity: Study of Intercultural Sensitivity of Students at Teacher Education Programs of Georgia

ERIC Educational Resources Information Center

Tabatadze, Shalva; Gorgadze, Natia

2018-01-01

Purpose: The purpose of this paper is to assess the intercultural sensitivity of students in teacher educational programs at higher education institutes (HEIs) in Georgia. Design/methodology/approach: This research explored the intercultural sensitivity among 355 randomly selected students in teacher education programs at higher education…

Sensitivity to Morphosyntactic Information in 3-Year-Old Children with Typical Language Development: A Feasibility Study

ERIC Educational Resources Information Center

Deevy, Patricia; Leonard, Laurence B.; Marchman, Virginia A.

2017-01-01

Purpose: This study tested the feasibility of a method designed to assess children's sensitivity to tense/agreement information in fronted auxiliaries during online comprehension of questions (e.g., "Are the nice little dogs running?"). We expected that a group of children who were proficient in auxiliary use would show this sensitivity,…

Results of an integrated structure-control law design sensitivity analysis

NASA Technical Reports Server (NTRS)

Gilbert, Michael G.

1988-01-01

Next generation air and space vehicle designs are driven by increased performance requirements, demanding a high level of design integration between traditionally separate design disciplines. Interdisciplinary analysis capabilities have been developed, for aeroservoelastic aircraft and large flexible spacecraft control for instance, but the requisite integrated design methods are only beginning to be developed. One integrated design method which has received attention is based on hierarchal problem decompositions, optimization, and design sensitivity analyses. This paper highlights a design sensitivity analysis method for Linear Quadratic Cost, Gaussian (LQG) optimal control laws, which predicts change in the optimal control law due to changes in fixed problem parameters using analytical sensitivity equations. Numerical results of a design sensitivity analysis for a realistic aeroservoelastic aircraft example are presented. In this example, the sensitivity of the optimally controlled aircraft's response to various problem formulation and physical aircraft parameters is determined. These results are used to predict the aircraft's new optimally controlled response if the parameter was to have some other nominal value during the control law design process. The sensitivity results are validated by recomputing the optimal control law for discrete variations in parameters, computing the new actual aircraft response, and comparing with the predicted response. These results show an improvement in sensitivity accuracy for integrated design purposes over methods which do not include changess in the optimal control law. Use of the analytical LQG sensitivity expressions is also shown to be more efficient that finite difference methods for the computation of the equivalent sensitivity information.

Shape design sensitivity analysis and optimization of three dimensional elastic solids using geometric modeling and automatic regridding. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Yao, Tse-Min; Choi, Kyung K.

1987-01-01

An automatic regridding method and a three dimensional shape design parameterization technique were constructed and integrated into a unified theory of shape design sensitivity analysis. An algorithm was developed for general shape design sensitivity analysis of three dimensional eleastic solids. Numerical implementation of this shape design sensitivity analysis method was carried out using the finite element code ANSYS. The unified theory of shape design sensitivity analysis uses the material derivative of continuum mechanics with a design velocity field that represents shape change effects over the structural design. Automatic regridding methods were developed by generating a domain velocity field with boundary displacement method. Shape design parameterization for three dimensional surface design problems was illustrated using a Bezier surface with boundary perturbations that depend linearly on the perturbation of design parameters. A linearization method of optimization, LINRM, was used to obtain optimum shapes. Three examples from different engineering disciplines were investigated to demonstrate the accuracy and versatility of this shape design sensitivity analysis method.

Overview of Sensitivity Analysis and Shape Optimization for Complex Aerodynamic Configurations

NASA Technical Reports Server (NTRS)

Newman, Perry A.; Newman, James C., III; Barnwell, Richard W.; Taylor, Arthur C., III; Hou, Gene J.-W.

1998-01-01

This paper presents a brief overview of some of the more recent advances in steady aerodynamic shape-design sensitivity analysis and optimization, based on advanced computational fluid dynamics. The focus here is on those methods particularly well- suited to the study of geometrically complex configurations and their potentially complex associated flow physics. When nonlinear state equations are considered in the optimization process, difficulties are found in the application of sensitivity analysis. Some techniques for circumventing such difficulties are currently being explored and are included here. Attention is directed to methods that utilize automatic differentiation to obtain aerodynamic sensitivity derivatives for both complex configurations and complex flow physics. Various examples of shape-design sensitivity analysis for unstructured-grid computational fluid dynamics algorithms are demonstrated for different formulations of the sensitivity equations. Finally, the use of advanced, unstructured-grid computational fluid dynamics in multidisciplinary analyses and multidisciplinary sensitivity analyses within future optimization processes is recommended and encouraged.

Numerical Simulation and Mechanical Design for TPS Electron Beam Position Monitors

NASA Astrophysics Data System (ADS)

Hsueh, H. P.; Kuan, C. K.; Ueng, T. S.; Hsiung, G. Y.; Chen, J. R.

2007-01-01

Comprehensive study on the mechanical design and numerical simulation for the high resolution electron beam position monitors are key steps to build the newly proposed 3rd generation synchrotron radiation research facility, Taiwan Photon Source (TPS). With more advanced electromagnetic simulation tool like MAFIA tailored specifically for particle accelerator, the design for the high resolution electron beam position monitors can be tested in such environment before they are experimentally tested. The design goal of our high resolution electron beam position monitors is to get the best resolution through sensitivity and signal optimization. The definitions and differences between resolution and sensitivity of electron beam position monitors will be explained. The design consideration is also explained. Prototype deign has been carried out and the related simulations were also carried out with MAFIA. The results are presented here. Sensitivity as high as 200 in x direction has been achieved in x direction at 500 MHz.

Manufacturing error sensitivity analysis and optimal design method of cable-network antenna structures

NASA Astrophysics Data System (ADS)

Zong, Yali; Hu, Naigang; Duan, Baoyan; Yang, Guigeng; Cao, Hongjun; Xu, Wanye

2016-03-01

Inevitable manufacturing errors and inconsistency between assumed and actual boundary conditions can affect the shape precision and cable tensions of a cable-network antenna, and even result in failure of the structure in service. In this paper, an analytical sensitivity analysis method of the shape precision and cable tensions with respect to the parameters carrying uncertainty was studied. Based on the sensitivity analysis, an optimal design procedure was proposed to alleviate the effects of the parameters that carry uncertainty. The validity of the calculated sensitivities is examined by those computed by a finite difference method. Comparison with a traditional design method shows that the presented design procedure can remarkably reduce the influence of the uncertainties on the antenna performance. Moreover, the results suggest that especially slender front net cables, thick tension ties, relatively slender boundary cables and high tension level can improve the ability of cable-network antenna structures to resist the effects of the uncertainties on the antenna performance.

Dynamic analysis of Apollo-Salyut/Soyuz docking

NASA Technical Reports Server (NTRS)

Schliesing, J. A.

1972-01-01

The use of a docking-system computer program in analyzing the dynamic environment produced by two impacting spacecraft and the attitude control systems is discussed. Performance studies were conducted to determine the mechanism load and capture sensitivity to parametric changes in the initial impact conditions. As indicated by the studies, capture latching is most sensitive to vehicle angular-alinement errors and is least sensitive to lateral-miss error. As proved by load-sensitivity studies, peak loads acting on the Apollo spacecraft are considerably lower than the Apollo design-limit loads.

Climate-sensitive urban design through Envi-Met simulation: case study in Kemayoran, Jakarta

NASA Astrophysics Data System (ADS)

Kusumastuty, K. D.; Poerbo, H. W.; Koerniawan, M. D.

2018-03-01

Indonesia as a tropical country which the character of its climate are hot and humid, the outdoor activity applications are often disrupted due to discomfort in thermal conditions. Massive construction of skyscrapers in urban areas are caused by the increase of human population leads to reduced green and infiltration areas that impact to environmental imbalances and triggering microclimate changes with rising air temperatures on the surface. The area that significantly experiences the rise of temperature in the Central Business District (CBD), which has need an analysis to create thermal comfort conditions to improve the ease of outdoor activities by an approach. This study aims to design the Kemayoran CBD through Climate Sensitive Urban Design especially in hot and humid tropical climate area and analyze thermal comfort level and optimal air conditioning in the outdoor area. This research used a quantitative method by generating the design using Climate Sensitive Urban Design principle through Envi-met 4.1 simulation program to find out the value of PMV, air temperature, wind speed and relative humidity conditions. The design area considers the configuration of buildings such as the distance between buildings, the average height, the orientation of the building, and the width of the road.

The Advanced Gamma-ray Imaging System (AGIS)-Simulation Studies

NASA Astrophysics Data System (ADS)

Maier, G.; Buckley, J.; Bugaev, V.; Fegan, S.; Funk, S.; Konopelko, A.; Vassiliev, V. V.

2008-12-01

The Advanced Gamma-ray Imaging System (AGIS) is a US-led concept for a next-generation instrument in ground-based very-high-energy gamma-ray astronomy. The most important design requirement for AGIS is a sensitivity of about 10 times greater than current observatories like Veritas, H.E.S.S or MAGIC. We present results of simulation studies of various possible designs for AGIS. The primary characteristics of the array performance, collecting area, angular resolution, background rejection, and sensitivity are discussed.

[Application of Fourier amplitude sensitivity test in Chinese healthy volunteer population pharmacokinetic model of tacrolimus].

PubMed

Guan, Zheng; Zhang, Guan-min; Ma, Ping; Liu, Li-hong; Zhou, Tian-yan; Lu, Wei

2010-07-01

In this study, we evaluated the influence of different variance from each of the parameters on the output of tacrolimus population pharmacokinetic (PopPK) model in Chinese healthy volunteers, using Fourier amplitude sensitivity test (FAST). Besides, we estimated the index of sensitivity within whole course of blood sampling, designed different sampling times, and evaluated the quality of parameters' and the efficiency of prediction. It was observed that besides CL1/F, the index of sensitivity for all of the other four parameters (V1/F, V2/F, CL2/F and k(a)) in tacrolimus PopPK model showed relatively high level and changed fast with the time passing. With the increase of the variance of k(a), its indices of sensitivity increased obviously, associated with significant decrease in sensitivity index for the other parameters, and obvious change in peak time as well. According to the simulation of NONMEM and the comparison among different fitting results, we found that the sampling time points designed according to FAST surpassed the other time points. It suggests that FAST can access the sensitivities of model parameters effectively, and assist the design of clinical sampling times and the construction of PopPK model.

Optimization of an ultralow-dose high-resolution pediatric PET scanner design based on monolithic scintillators with dual-sided digital SiPM readout: a simulation study

NASA Astrophysics Data System (ADS)

Mikhaylova, Ekaterina; Tabacchini, Valerio; Borghi, Giacomo; Mollet, Pieter; D'Hoe, Ester; Schaart, Dennis R.; Vandenberghe, Stefaan

2017-11-01

The goal of this simulation study is the performance evaluation and comparison of six potential designs for a time-of-flight PET scanner for pediatric patients of up to about 12 years of age. It is designed to have a high sensitivity and provide high-contrast and high-resolution images. The simulated pediatric PET is a full ring scanner, consisting of 32  ×  32 mm2 monolithic LYSO:Ce crystals coupled to digital silicon photomultiplier arrays. The six considered designs differ in axial lengths (27.2 cm, 54.4 cm and 102 cm) and crystal thicknesses (22 mm and 11 mm). The simulations are based on measured detector response data. We study two possible detector arrangements: 22 mm-thick crystals with dual-sided readout and 11 mm-thick crystals with back-sided readout. The six designs are simulated by means of the GEANT4 application for tomographic emission software, using the measured spatial, energy and time response of the monolithic scintillator detectors as input. The performance of the six designs is compared on the basis of four studies: (1) spatial resolution; (2) NEMA NU2-2012 sensitivity and scatter fraction (SF) tests; (3) non-prewhitening signal-to-noise ratio observer study; and (4) receiver operating characteristics analysis. Based on the results, two designs are identified as cost-effective solutions for fast and efficient imaging of children: one with 54.4 cm axial field-of-view (FOV) and 22 mm-thick crystals, and another one with 102 cm axial FOV and 11 cm-thick crystals. The first one has a higher center point sensitivity than the second one, but requires dual-sided readout. The second design has the advantage of allowing a whole-body scan in a single bed position acquisition. Both designs have the potential to provide an excellent spatial resolution (˜2 mm) and an ultra-high sensitivity (>100 cps kBq-1 ).

Methodology for sensitivity analysis, approximate analysis, and design optimization in CFD for multidisciplinary applications. [computational fluid dynamics

NASA Technical Reports Server (NTRS)

Taylor, Arthur C., III; Hou, Gene W.

1992-01-01

Fundamental equations of aerodynamic sensitivity analysis and approximate analysis for the two dimensional thin layer Navier-Stokes equations are reviewed, and special boundary condition considerations necessary to apply these equations to isolated lifting airfoils on 'C' and 'O' meshes are discussed in detail. An efficient strategy which is based on the finite element method and an elastic membrane representation of the computational domain is successfully tested, which circumvents the costly 'brute force' method of obtaining grid sensitivity derivatives, and is also useful in mesh regeneration. The issue of turbulence modeling is addressed in a preliminary study. Aerodynamic shape sensitivity derivatives are efficiently calculated, and their accuracy is validated on two viscous test problems, including: (1) internal flow through a double throat nozzle, and (2) external flow over a NACA 4-digit airfoil. An automated aerodynamic design optimization strategy is outlined which includes the use of a design optimization program, an aerodynamic flow analysis code, an aerodynamic sensitivity and approximate analysis code, and a mesh regeneration and grid sensitivity analysis code. Application of the optimization methodology to the two test problems in each case resulted in a new design having a significantly improved performance in the aerodynamic response of interest.

Monte Carlo studies of medium-size telescope designs for the Cherenkov Telescope Array

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wood, M. D.; Jogler, T.; Dumm, J.

In this paper, we present studies for optimizing the next generation of ground-based imaging atmospheric Cherenkov telescopes (IACTs). Results focus on mid-sized telescopes (MSTs) for CTA, detecting very high energy gamma rays in the energy range from a few hundred GeV to a few tens of TeV. We describe a novel, flexible detector Monte Carlo package, FAST (FAst Simulation for imaging air cherenkov Telescopes), that we use to simulate different array and telescope designs. The simulation is somewhat simplified to allow for efficient exploration over a large telescope design parameter space. We investigate a wide range of telescope performance parametersmore » including optical resolution, camera pixel size, and light collection area. In order to ensure a comparison of the arrays at their maximum sensitivity, we analyze the simulations with the most sensitive techniques used in the field, such as maximum likelihood template reconstruction and boosted decision trees for background rejection. Choosing telescope design parameters representative of the proposed Davies–Cotton (DC) and Schwarzchild–Couder (SC) MST designs, we compare the performance of the arrays by examining the gamma-ray angular resolution and differential point-source sensitivity. We further investigate the array performance under a wide range of conditions, determining the impact of the number of telescopes, telescope separation, night sky background, and geomagnetic field. We find a 30–40% improvement in the gamma-ray angular resolution at all energies when comparing arrays with an equal number of SC and DC telescopes, significantly enhancing point-source sensitivity in the MST energy range. Finally, we attribute the increase in point-source sensitivity to the improved optical point-spread function and smaller pixel size of the SC telescope design.« less

Monte Carlo studies of medium-size telescope designs for the Cherenkov Telescope Array

DOE PAGES

Wood, M. D.; Jogler, T.; Dumm, J.; ...

2015-06-07

In this paper, we present studies for optimizing the next generation of ground-based imaging atmospheric Cherenkov telescopes (IACTs). Results focus on mid-sized telescopes (MSTs) for CTA, detecting very high energy gamma rays in the energy range from a few hundred GeV to a few tens of TeV. We describe a novel, flexible detector Monte Carlo package, FAST (FAst Simulation for imaging air cherenkov Telescopes), that we use to simulate different array and telescope designs. The simulation is somewhat simplified to allow for efficient exploration over a large telescope design parameter space. We investigate a wide range of telescope performance parametersmore » including optical resolution, camera pixel size, and light collection area. In order to ensure a comparison of the arrays at their maximum sensitivity, we analyze the simulations with the most sensitive techniques used in the field, such as maximum likelihood template reconstruction and boosted decision trees for background rejection. Choosing telescope design parameters representative of the proposed Davies–Cotton (DC) and Schwarzchild–Couder (SC) MST designs, we compare the performance of the arrays by examining the gamma-ray angular resolution and differential point-source sensitivity. We further investigate the array performance under a wide range of conditions, determining the impact of the number of telescopes, telescope separation, night sky background, and geomagnetic field. We find a 30–40% improvement in the gamma-ray angular resolution at all energies when comparing arrays with an equal number of SC and DC telescopes, significantly enhancing point-source sensitivity in the MST energy range. Finally, we attribute the increase in point-source sensitivity to the improved optical point-spread function and smaller pixel size of the SC telescope design.« less

Sensitivity study for a remotely piloted microwave-powered sailplane used as a high-altitude observation

NASA Technical Reports Server (NTRS)

Turriziani, R. V.

1979-01-01

The sensitivity of several performance characteristics of a proposed design for a microwave-powered, remotely piloted, high-altitude sailplane to changes in independently varied design parameters was investigated. Results were expressed as variations from baseline values of range, final climb altitude and onboard storage of radiated energy. Calculated range decreased with increases in either gross weight or parasite drag coefficient; it also decreased with decreases in lift coefficient, propeller efficiency, or microwave beam density. The sensitivity trends for range and final climb altitude were very similar. The sensitivity trends for stored energy were reversed from those for range, except for decreasing microwave beam density. Some study results for single parameter variations were combined to estimate the effect of the simultaneous variation of several parameters: for two parameters, this appeared to give reasonably accurate results.

Mechanical Structural Design of a MEMS-Based Piezoresistive Accelerometer for Head Injuries Monitoring: A Computational Analysis by Increments of the Sensor Mass Moment of Inertia †

PubMed Central

Messina, Marco; Njuguna, James; Palas, Chrysovalantis

2018-01-01

This work focuses on the proof-mass mechanical structural design improvement of a tri-axial piezoresistive accelerometer specifically designed for head injuries monitoring where medium-G impacts are common; for example, in sports such as racing cars or American Football. The device requires the highest sensitivity achievable with a single proof-mass approach, and a very low error (<1%) as the accuracy for these types of applications is paramount. The optimization method differs from previous work as it is based on the progressive increment of the sensor proof-mass mass moment of inertia (MMI) in all three axes. Three different designs are presented in this study, where at each step of design evolution, the MMI of the sensor proof-mass gradually increases in all axes. The work numerically demonstrates that an increment of MMI determines an increment of device sensitivity with a simultaneous reduction of cross-axis sensitivity in the particular axis under study. This is due to the linkage between the external applied stress and the distribution of mass (of the proof-mass), and therefore of its mass moment of inertia. Progressively concentrating the mass on the axes where the piezoresistors are located (i.e., x- and y-axis) by increasing the MMI in the x- and y-axis, will undoubtedly increase the longitudinal stresses applied in that areas for a given external acceleration, therefore increasing the piezoresistors fractional resistance change and eventually positively affecting the sensor sensitivity. The final device shows a sensitivity increase of about 80% in the z-axis and a reduction of cross-axis sensitivity of 18% respect to state-of-art sensors available in the literature from a previous work of the authors. Sensor design, modelling, and optimization are presented, concluding the work with results, discussion, and conclusion. PMID:29351221

Numerical study on tailoring the shock sensitivity of TATB-based explosives using mesostructural features

NASA Astrophysics Data System (ADS)

Springer, H. Keo

2017-06-01

Advanced manufacturing techniques offer control of explosive mesostructures necessary to tailor its shock sensitivity. However, structure-property relationships are not well established for explosives so there is little material design guidance for these techniques. The objective of this numerical study is to demonstrate how TATB-based explosives can be sensitized to shocks using mesostructural features. For this study, we use LX-17 (92.5%wt TATB, 7.5%wt Kel-F 800) as the prototypical TATB-based explosive. We employ features with different geometries and materials. HMX-based explosive features, high shock impedance features, and pores are used to sensitive the LX-17. Simulations are performed in the multi-physics hydrocode, ALE3D. A reactive flow model is used to simulate the shock initiation response of the explosives. Our metric for shock sensitivity in this study is run distance to detonation as a function of applied pressure. These numerical studies are important because they guide the design of novel energetic materials. This work was performed under the auspices of the United States Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-724986.

Culturally Sensitive Interventions and Substance Use: A Meta-Analytic Review of Outcomes among Minority Youths

ERIC Educational Resources Information Center

Hodge, David R.; Jackson, Kelly F.; Vaughn, Michael G.

2012-01-01

This study assessed the effectiveness of culturally sensitive interventions (CSIs) ("N" = 10) designed to address substance use among minority youths. Study methods consisted of systematic search procedures, quality of study ratings, and meta-analytic techniques to gauge effects and evaluate publication bias. The results, across all measures and…

Observations Regarding Use of Advanced CFD Analysis, Sensitivity Analysis, and Design Codes in MDO

NASA Technical Reports Server (NTRS)

Newman, Perry A.; Hou, Gene J. W.; Taylor, Arthur C., III

1996-01-01

Observations regarding the use of advanced computational fluid dynamics (CFD) analysis, sensitivity analysis (SA), and design codes in gradient-based multidisciplinary design optimization (MDO) reflect our perception of the interactions required of CFD and our experience in recent aerodynamic design optimization studies using CFD. Sample results from these latter studies are summarized for conventional optimization (analysis - SA codes) and simultaneous analysis and design optimization (design code) using both Euler and Navier-Stokes flow approximations. The amount of computational resources required for aerodynamic design using CFD via analysis - SA codes is greater than that required for design codes. Thus, an MDO formulation that utilizes the more efficient design codes where possible is desired. However, in the aerovehicle MDO problem, the various disciplines that are involved have different design points in the flight envelope; therefore, CFD analysis - SA codes are required at the aerodynamic 'off design' points. The suggested MDO formulation is a hybrid multilevel optimization procedure that consists of both multipoint CFD analysis - SA codes and multipoint CFD design codes that perform suboptimizations.

Evolution of Geometric Sensitivity Derivatives from Computer Aided Design Models

NASA Technical Reports Server (NTRS)

Jones, William T.; Lazzara, David; Haimes, Robert

2010-01-01

The generation of design parameter sensitivity derivatives is required for gradient-based optimization. Such sensitivity derivatives are elusive at best when working with geometry defined within the solid modeling context of Computer-Aided Design (CAD) systems. Solid modeling CAD systems are often proprietary and always complex, thereby necessitating ad hoc procedures to infer parameter sensitivity. A new perspective is presented that makes direct use of the hierarchical associativity of CAD features to trace their evolution and thereby track design parameter sensitivity. In contrast to ad hoc methods, this method provides a more concise procedure following the model design intent and determining the sensitivity of CAD geometry directly to its respective defining parameters.

Conceptual design and analysis of a dynamic scale model of the Space Station Freedom

NASA Technical Reports Server (NTRS)

Davis, D. A.; Gronet, M. J.; Tan, M. K.; Thorne, J.

1994-01-01

This report documents the conceptual design study performed to evaluate design options for a subscale dynamic test model which could be used to investigate the expected on-orbit structural dynamic characteristics of the Space Station Freedom early build configurations. The baseline option was a 'near-replica' model of the SSF SC-7 pre-integrated truss configuration. The approach used to develop conceptual design options involved three sets of studies: evaluation of the full-scale design and analysis databases, conducting scale factor trade studies, and performing design sensitivity studies. The scale factor trade study was conducted to develop a fundamental understanding of the key scaling parameters that drive design, performance and cost of a SSF dynamic scale model. Four scale model options were estimated: 1/4, 1/5, 1/7, and 1/10 scale. Prototype hardware was fabricated to assess producibility issues. Based on the results of the study, a 1/4-scale size is recommended based on the increased model fidelity associated with a larger scale factor. A design sensitivity study was performed to identify critical hardware component properties that drive dynamic performance. A total of 118 component properties were identified which require high-fidelity replication. Lower fidelity dynamic similarity scaling can be used for non-critical components.

Application-oriented computational studies on a series of D-π-A structured porphyrin sensitizers with different electron-donor groups.

PubMed

Fan, Chencheng; Zhang, Bao; Li, Yuanchao; Liang, Yuxia; Xue, Xiaodong; Feng, Yaqing

2015-11-11

A series of D-π-A zinc porphyrin sensitizers bearing a substituted iminodibenzyl group at the porphyrin meso position, which is expected to have different electron-donating abilities, were designed. Theoretical studies were performed to examine the photovoltaic properties of these molecules in dye-sensitized solar cells (DSSCs). In particular, the important concepts, the Fukui function and the extended condensed Fukui function, are employed to describe the electron-donating abilities accurately at the quantitative level. Tangui Le Bahers model was adopted to analyze charge transfer (CT) during electron transition. A correlation between the electron donating abilities of the derived iminodibenzyl group and CT was built to evaluate the cell performance based on sensitizers . The theoretical studies showed that porphyrins bearing an extremely strong electron-donating group (EDG) would fail in the generation of photocurrent in the closed circuit when applied in DSSCs due to the higher level of the HOMO energy than the redox potential of the redox couple (I(-)/I3(-)). The one with a weaker EDG () is expected to show better photovoltaic performance than porphyrin with an unsubstituted iminodibenzyl group. This study demonstrates a reliable method involving the employment of the Fukui function, the extended condensed Fukui function and the Tangui Le Bahers model for the evaluation of newly designed D-π-A type porphyrin sensitizers for use in DSSCs, and as guidance for future molecular design.

Development of LC-13C NMR

NASA Technical Reports Server (NTRS)

Dorn, H. C.; Wang, J. S.; Glass, T. E.

1986-01-01

This study involves the development of C-13 nuclear resonance as an on-line detector for liquid chromatography (LC-C-13 NMR) for the chemical characterization of aviation fuels. The initial focus of this study was the development of a high sensitivity flow C-13 NMR probe. Since C-13 NMR sensitivity is of paramount concern, considerable effort during the first year was directed at new NMR probe designs. In particular, various toroid coil designs were examined. In addition, corresponding shim coils for correcting the main magnetic field (B sub 0) homogeneity were examined. Based on these initial probe design studies, an LC-C-13 NMR probe was built and flow C-13 NMR data was obtained for a limited number of samples.

Sensitivity of Space Station alpha joint robust controller to structural modal parameter variations

NASA Technical Reports Server (NTRS)

Kumar, Renjith R.; Cooper, Paul A.; Lim, Tae W.

1991-01-01

The photovoltaic array sun tracking control system of Space Station Freedom is described. A synthesis procedure for determining optimized values of the design variables of the control system is developed using a constrained optimization technique. The synthesis is performed to provide a given level of stability margin, to achieve the most responsive tracking performance, and to meet other design requirements. Performance of the baseline design, which is synthesized using predicted structural characteristics, is discussed and the sensitivity of the stability margin is examined for variations of the frequencies, mode shapes and damping ratios of dominant structural modes. The design provides enough robustness to tolerate a sizeable error in the predicted modal parameters. A study was made of the sensitivity of performance indicators as the modal parameters of the dominant modes vary. The design variables are resynthesized for varying modal parameters in order to achieve the most responsive tracking performance while satisfying the design requirements. This procedure of reoptimization design parameters would be useful in improving the control system performance if accurate model data are provided.

Design component method for sensitivity analysis of built-up structures

NASA Technical Reports Server (NTRS)

Choi, Kyung K.; Seong, Hwai G.

1986-01-01

A 'design component method' that provides a unified and systematic organization of design sensitivity analysis for built-up structures is developed and implemented. Both conventional design variables, such as thickness and cross-sectional area, and shape design variables of components of built-up structures are considered. It is shown that design of components of built-up structures can be characterized and system design sensitivity expressions obtained by simply adding contributions from each component. The method leads to a systematic organization of computations for design sensitivity analysis that is similar to the way in which computations are organized within a finite element code.

Tradeoff studies in multiobjective insensitive design of airplane control systems

NASA Technical Reports Server (NTRS)

Schy, A. A.; Giesy, D. P.

1983-01-01

A computer aided design method for multiobjective parameter-insensitive design of airplane control systems is described. Methods are presented for trading off nominal values of design objectives against sensitivities of the design objectives to parameter uncertainties, together with guidelines for designer utilization of the methods. The methods are illustrated by application to the design of a lateral stability augmentation system for two supersonic flight conditions of the Shuttle Orbiter. Objective functions are conventional handling quality measures and peak magnitudes of control deflections and rates. The uncertain parameters are assumed Gaussian, and numerical approximations of the stochastic behavior of the objectives are described. Results of applying the tradeoff methods to this example show that stochastic-insensitive designs are distinctly different from deterministic multiobjective designs. The main penalty for achieving significant decrease in sensitivity is decreased speed of response for the nominal system.

Efficient hiding of confidential high-utility itemsets with minimal side effects

NASA Astrophysics Data System (ADS)

Lin, Jerry Chun-Wei; Hong, Tzung-Pei; Fournier-Viger, Philippe; Liu, Qiankun; Wong, Jia-Wei; Zhan, Justin

2017-11-01

Privacy preserving data mining (PPDM) is an emerging research problem that has become critical in the last decades. PPDM consists of hiding sensitive information to ensure that it cannot be discovered by data mining algorithms. Several PPDM algorithms have been developed. Most of them are designed for hiding sensitive frequent itemsets or association rules. Hiding sensitive information in a database can have several side effects such as hiding other non-sensitive information and introducing redundant information. Finding the set of itemsets or transactions to be sanitised that minimises side effects is an NP-hard problem. In this paper, a genetic algorithm (GA) using transaction deletion is designed to hide sensitive high-utility itemsets for PPUM. A flexible fitness function with three adjustable weights is used to evaluate the goodness of each chromosome for hiding sensitive high-utility itemsets. To speed up the evolution process, the pre-large concept is adopted in the designed algorithm. It reduces the number of database scans required for verifying the goodness of an evaluated chromosome. Substantial experiments are conducted to compare the performance of the designed GA approach (with/without the pre-large concept), with a GA-based approach relying on transaction insertion and a non-evolutionary algorithm, in terms of execution time, side effects, database integrity and utility integrity. Results demonstrate that the proposed algorithm hides sensitive high-utility itemsets with fewer side effects than previous studies, while preserving high database and utility integrity.

Error analysis and prevention of cosmic ion-induced soft errors in static CMOS RAMs

NASA Astrophysics Data System (ADS)

Diehl, S. E.; Ochoa, A., Jr.; Dressendorfer, P. V.; Koga, P.; Kolasinski, W. A.

1982-12-01

Cosmic ray interactions with memory cells are known to cause temporary, random, bit errors in some designs. The sensitivity of polysilicon gate CMOS static RAM designs to logic upset by impinging ions has been studied using computer simulations and experimental heavy ion bombardment. Results of the simulations are confirmed by experimental upset cross-section data. Analytical models have been extended to determine and evaluate design modifications which reduce memory cell sensitivity to cosmic ions. A simple design modification, the addition of decoupling resistance in the feedback path, is shown to produce static RAMs immune to cosmic ray-induced bit errors.

Coal gasification systems engineering and analysis, volume 2

NASA Technical Reports Server (NTRS)

1980-01-01

The major design related features of each generic plant system were characterized in a catalog. Based on the catalog and requirements data, approximately 17 designs and cost estimates were developed for MBG and alternate products. A series of generic trade studies was conducted to support all of the design studies. A set of cost and programmatic analyses were conducted to supplement the designs. The cost methodology employed for the design and sensitivity studies was documented and implemented in a computer program. Plant design and construction schedules were developed for the K-T, Texaco, and B&W MBG plant designs. A generic work breakdown structure was prepared, based on the K-T design, to coincide with TVA's planned management approach. An extensive set of cost sensitivity analyses was completed for K-T, Texaco, and B&W design. Product price competitiveness was evaluated for MBG and the alternate products. A draft management policy and procedures manual was evaluated. A supporting technology development plan was developed to address high technology risk issues. The issues were identified and ranked in terms of importance and tractability, and a plan developed for obtaining data or developing technology required to mitigate the risk.

Shape design sensitivity analysis and optimal design of structural systems

NASA Technical Reports Server (NTRS)

Choi, Kyung K.

1987-01-01

The material derivative concept of continuum mechanics and an adjoint variable method of design sensitivity analysis are used to relate variations in structural shape to measures of structural performance. A domain method of shape design sensitivity analysis is used to best utilize the basic character of the finite element method that gives accurate information not on the boundary but in the domain. Implementation of shape design sensitivty analysis using finite element computer codes is discussed. Recent numerical results are used to demonstrate the accuracy obtainable using the method. Result of design sensitivity analysis is used to carry out design optimization of a built-up structure.

Development of Multiobjective Optimization Techniques for Sonic Boom Minimization

NASA Technical Reports Server (NTRS)

Chattopadhyay, Aditi; Rajadas, John Narayan; Pagaldipti, Naryanan S.

1996-01-01

A discrete, semi-analytical sensitivity analysis procedure has been developed for calculating aerodynamic design sensitivities. The sensitivities of the flow variables and the grid coordinates are numerically calculated using direct differentiation of the respective discretized governing equations. The sensitivity analysis techniques are adapted within a parabolized Navier Stokes equations solver. Aerodynamic design sensitivities for high speed wing-body configurations are calculated using the semi-analytical sensitivity analysis procedures. Representative results obtained compare well with those obtained using the finite difference approach and establish the computational efficiency and accuracy of the semi-analytical procedures. Multidisciplinary design optimization procedures have been developed for aerospace applications namely, gas turbine blades and high speed wing-body configurations. In complex applications, the coupled optimization problems are decomposed into sublevels using multilevel decomposition techniques. In cases with multiple objective functions, formal multiobjective formulation such as the Kreisselmeier-Steinhauser function approach and the modified global criteria approach have been used. Nonlinear programming techniques for continuous design variables and a hybrid optimization technique, based on a simulated annealing algorithm, for discrete design variables have been used for solving the optimization problems. The optimization procedure for gas turbine blades improves the aerodynamic and heat transfer characteristics of the blades. The two-dimensional, blade-to-blade aerodynamic analysis is performed using a panel code. The blade heat transfer analysis is performed using an in-house developed finite element procedure. The optimization procedure yields blade shapes with significantly improved velocity and temperature distributions. The multidisciplinary design optimization procedures for high speed wing-body configurations simultaneously improve the aerodynamic, the sonic boom and the structural characteristics of the aircraft. The flow solution is obtained using a comprehensive parabolized Navier Stokes solver. Sonic boom analysis is performed using an extrapolation procedure. The aircraft wing load carrying member is modeled as either an isotropic or a composite box beam. The isotropic box beam is analyzed using thin wall theory. The composite box beam is analyzed using a finite element procedure. The developed optimization procedures yield significant improvements in all the performance criteria and provide interesting design trade-offs. The semi-analytical sensitivity analysis techniques offer significant computational savings and allow the use of comprehensive analysis procedures within design optimization studies.

Results of an integrated structure/control law design sensitivity analysis

NASA Technical Reports Server (NTRS)

Gilbert, Michael G.

1989-01-01

A design sensitivity analysis method for Linear Quadratic Cost, Gaussian (LQG) optimal control laws, which predicts change in the optimal control law due to changes in fixed problem parameters using analytical sensitivity equations is discussed. Numerical results of a design sensitivity analysis for a realistic aeroservoelastic aircraft example are presented. In this example, the sensitivity of the optimally controlled aircraft's response to various problem formulation and physical aircraft parameters is determined. These results are used to predict the aircraft's new optimally controlled response if the parameter was to have some other nominal value during the control law design process. The sensitivity results are validated by recomputing the optimal control law for discrete variations in parameters, computing the new actual aircraft response, and comparing with the predicted response. These results show an improvement in sensitivity accuracy for integrated design purposes over methods which do not include changes in the optimal control law. Use of the analytical LQG sensitivity expressions is also shown to be more efficient than finite difference methods for the computation of the equivalent sensitivity information.

Floor vibration evaluations for medical facilities

NASA Astrophysics Data System (ADS)

Himmel, Chad N.

2003-10-01

The structural floor design for new medical facilities is often selected early in the design phase and in renovation projects, the floor structure already exists. Because the floor structure can often have an influence on the location of vibration sensitive medical equipment and facilities, it is becoming necessary to identify the best locations for equipment and facilities early in the design process. Even though specific criteria for vibration-sensitive uses and equipment may not always be available early in the design phase, it should be possible to determine compatible floor structures for planned vibration-sensitive uses by comparing conceptual layouts with generic floor vibration criteria. Relatively simple evaluations of planned uses and generic criteria, combined with on-site vibration and noise measurements early in design phase, can significantly reduce future design problems and expense. Concepts of evaluation procedures and analyses will be presented in this paper. Generic floor vibration criteria and appropriate parameters to control resonant floor vibration and noise will be discussed for typical medical facilities and medical research facilities. Physical, economic, and logistical limitations that affect implementation will be discussed through case studies.

A Statistical Simulation Approach to Safe Life Fatigue Analysis of Redundant Metallic Components

NASA Technical Reports Server (NTRS)

Matthews, William T.; Neal, Donald M.

1997-01-01

This paper introduces a dual active load path fail-safe fatigue design concept analyzed by Monte Carlo simulation. The concept utilizes the inherent fatigue life differences between selected pairs of components for an active dual path system, enhanced by a stress level bias in one component. The design is applied to a baseline design; a safe life fatigue problem studied in an American Helicopter Society (AHS) round robin. The dual active path design is compared with a two-element standby fail-safe system and the baseline design for life at specified reliability levels and weight. The sensitivity of life estimates for both the baseline and fail-safe designs was examined by considering normal and Weibull distribution laws and coefficient of variation levels. Results showed that the biased dual path system lifetimes, for both the first element failure and residual life, were much greater than for standby systems. The sensitivity of the residual life-weight relationship was not excessive at reliability levels up to R = 0.9999 and the weight penalty was small. The sensitivity of life estimates increases dramatically at higher reliability levels.

A new u-statistic with superior design sensitivity in matched observational studies.

PubMed

Rosenbaum, Paul R

2011-09-01

In an observational or nonrandomized study of treatment effects, a sensitivity analysis indicates the magnitude of bias from unmeasured covariates that would need to be present to alter the conclusions of a naïve analysis that presumes adjustments for observed covariates suffice to remove all bias. The power of sensitivity analysis is the probability that it will reject a false hypothesis about treatment effects allowing for a departure from random assignment of a specified magnitude; in particular, if this specified magnitude is "no departure" then this is the same as the power of a randomization test in a randomized experiment. A new family of u-statistics is proposed that includes Wilcoxon's signed rank statistic but also includes other statistics with substantially higher power when a sensitivity analysis is performed in an observational study. Wilcoxon's statistic has high power to detect small effects in large randomized experiments-that is, it often has good Pitman efficiency-but small effects are invariably sensitive to small unobserved biases. Members of this family of u-statistics that emphasize medium to large effects can have substantially higher power in a sensitivity analysis. For example, in one situation with 250 pair differences that are Normal with expectation 1/2 and variance 1, the power of a sensitivity analysis that uses Wilcoxon's statistic is 0.08 while the power of another member of the family of u-statistics is 0.66. The topic is examined by performing a sensitivity analysis in three observational studies, using an asymptotic measure called the design sensitivity, and by simulating power in finite samples. The three examples are drawn from epidemiology, clinical medicine, and genetic toxicology. © 2010, The International Biometric Society.

Design sensitivity analysis and optimization tool (DSO) for sizing design applications

NASA Technical Reports Server (NTRS)

Chang, Kuang-Hua; Choi, Kyung K.; Perng, Jyh-Hwa

1992-01-01

The DSO tool, a structural design software system that provides the designer with a graphics-based menu-driven design environment to perform easy design optimization for general applications, is presented. Three design stages, preprocessing, design sensitivity analysis, and postprocessing, are implemented in the DSO to allow the designer to carry out the design process systematically. A framework, including data base, user interface, foundation class, and remote module, has been designed and implemented to facilitate software development for the DSO. A number of dedicated commercial software/packages have been integrated in the DSO to support the design procedures. Instead of parameterizing an FEM, design parameters are defined on a geometric model associated with physical quantities, and the continuum design sensitivity analysis theory is implemented to compute design sensitivity coefficients using postprocessing data from the analysis codes. A tracked vehicle road wheel is given as a sizing design application to demonstrate the DSO's easy and convenient design optimization process.

Application of design sensitivity analysis for greater improvement on machine structural dynamics

NASA Technical Reports Server (NTRS)

Yoshimura, Masataka

1987-01-01

Methodologies are presented for greatly improving machine structural dynamics by using design sensitivity analyses and evaluative parameters. First, design sensitivity coefficients and evaluative parameters of structural dynamics are described. Next, the relations between the design sensitivity coefficients and the evaluative parameters are clarified. Then, design improvement procedures of structural dynamics are proposed for the following three cases: (1) addition of elastic structural members, (2) addition of mass elements, and (3) substantial charges of joint design variables. Cases (1) and (2) correspond to the changes of the initial framework or configuration, and (3) corresponds to the alteration of poor initial design variables. Finally, numerical examples are given for demonstrating the availability of the methods proposed.

Maternal Sensitivity and Children's Behavior Problems: Examining the Moderating Role of Infant Sleep Duration

ERIC Educational Resources Information Center

Bordeleau, Stephanie; Bernier, Annie; Carrier, Julie

2012-01-01

The current study aimed to examine infant sleep duration as a moderator of the relations between maternal sensitivity and child externalizing and internalizing symptoms, in a prospective longitudinal design. Fifty-five Caucasian infants (33 girls) took part in 2 assessments, at 1 and 4 years. Maternal sensitivity was rated at 1 year, based on…

The complexity of personality: advantages of a genetically sensitive multi-group design.

PubMed

Hahn, Elisabeth; Spinath, Frank M; Siedler, Thomas; Wagner, Gert G; Schupp, Jürgen; Kandler, Christian

2012-03-01

Findings from many behavioral genetic studies utilizing the classical twin design suggest that genetic and non-shared environmental effects play a significant role in human personality traits. This study focuses on the methodological advantages of extending the sampling frame to include multiple dyads of relatives. We investigated the sensitivity of heritability estimates to the inclusion of sibling pairs, mother-child pairs and grandparent-grandchild pairs from the German Socio-Economic Panel Study in addition to a classical German twin sample consisting of monozygotic- and dizygotic twins. The resulting dataset contained 1.308 pairs, including 202 monozygotic and 147 dizygotic twin pairs, along with 419 sibling pairs, 438 mother-child dyads, and 102 grandparent-child dyads. This genetically sensitive multi-group design allowed the simultaneous testing of additive and non-additive genetic, common and specific environmental effects, including cultural transmission and twin-specific environmental influences. Using manifest and latent modeling of phenotypes (i.e., controlling for measurement error), we compare results from the extended sample with those from the twin sample alone and discuss implications for future research.

Mechanical design optimization of a single-axis MOEMS accelerometer based on a grating interferometry cavity for ultrahigh sensitivity

NASA Astrophysics Data System (ADS)

Lu, Qianbo; Bai, Jian; Wang, Kaiwei; Lou, Shuqi; Jiao, Xufen; Han, Dandan; Yang, Guoguang

2016-08-01

The ultrahigh static displacement-acceleration sensitivity of a mechanical sensing chip is essential primarily for an ultrasensitive accelerometer. In this paper, an optimal design to implement to a single-axis MOEMS accelerometer consisting of a grating interferometry cavity and a micromachined sensing chip is presented. The micromachined sensing chip is composed of a proof mass along with its mechanical cantilever suspension and substrate. The dimensional parameters of the sensing chip, including the length, width, thickness and position of the cantilevers are evaluated and optimized both analytically and by finite-element-method (FEM) simulation to yield an unprecedented acceleration-displacement sensitivity. Compared with one of the most sensitive single-axis MOEMS accelerometers reported in the literature, the optimal mechanical design can yield a profound sensitivity improvement with an equal footprint area, specifically, 200% improvement in displacement-acceleration sensitivity with moderate resonant frequency and dynamic range. The modified design was microfabricated, packaged with the grating interferometry cavity and tested. The experimental results demonstrate that the MOEMS accelerometer with modified design can achieve the acceleration-displacement sensitivity of about 150μm/g and acceleration sensitivity of greater than 1500V/g, which validates the effectiveness of the optimal design.

Nervous System Sensitization as a Predictor of Outcome in the Treatment of Peripheral Musculoskeletal Conditions: A Systematic Review.

PubMed

O'Leary, Helen; Smart, Keith M; Moloney, Niamh A; Doody, Catherine M

2017-02-01

Research suggests that peripheral and central nervous system sensitization can contribute to the overall pain experience in peripheral musculoskeletal (MSK) conditions. It is unclear, however, whether sensitization of the nervous system results in poorer outcomes following the treatment. This systematic review investigated whether nervous system sensitization in peripheral MSK conditions predicts poorer clinical outcomes in response to a surgical or conservative intervention. Four electronic databases were searched to identify the relevant studies. Eligible studies had a prospective design, with a follow-up assessing the outcome in terms of pain or disability. Studies that used baseline indices of nervous system sensitization were included, such as quantitative sensory testing (QST) or questionnaires that measured centrally mediated symptoms. Thirteen studies met the inclusion criteria, of which six were at a high risk of bias. The peripheral MSK conditions investigated were knee and hip osteoarthritis, shoulder pain, and elbow tendinopathy. QST parameters indicative of sensitization (lower electrical pain thresholds, cold hyperalgesia, enhanced temporal summation, lower punctate sharpness thresholds) were associated with negative outcome (more pain or disability) in 5 small exploratory studies. Larger studies that accounted for multiple confounders in design and analysis did not support a predictive relationship between QST parameters and outcome. Two studies used self-report measures to capture comorbid centrally mediated symptoms, and found higher questionnaire scores were independently predictive of more persistent pain following a total joint arthroplasty. This systematic review found insufficient evidence to support an independent predictive relationship between QST measures of nervous system sensitization and treatment outcome. Self-report measures demonstrated better predictive ability. Further high-quality prognostic research is warranted. © 2016 World Institute of Pain.

Optimization of geometric characteristics to improve sensing performance of MEMS piezoresistive strain sensors

NASA Astrophysics Data System (ADS)

Mohammed, Ahmed A. S.; Moussa, Walied A.; Lou, Edmond

2010-01-01

In this paper, the design of MEMS piezoresistive strain sensor is described. ANSYS®, finite element analysis (FEA) software, was used as a tool to model the performance of the silicon-based sensor. The incorporation of stress concentration regions (SCRs), to localize stresses, was explored in detail. This methodology employs the structural design of the sensor silicon carrier. Therefore, the induced strain in the sensing chip yielded stress concentration in the vicinity of the SCRs. Hence, this concept was proved to enhance the sensor sensitivity. Another advantage of the SCRs is to reduce the sensor transverse gauge factor, which offered a great opportunity to develop a MEMS sensor with minimal cross sensitivity. Two basic SCR designs were studied. The depth of the SCRs was also investigated. Moreover, FEA simulation is utilized to investigate the effect of the sensing element depth on the sensor sensitivity. Simulation results showed that the sensor sensitivity is independent of the piezoresistors' depth. The microfabrication process flow was introduced to prototype the different sensor designs. The experiments covered operating temperature range from -50 °C to +50 °C. Finally, packaging scheme and bonding adhesive selection were discussed. The experimental results showed good agreement with the FEA simulation results. The findings of this study confirmed the feasibility of introducing SCRs in the sensor silicon carrier to improve the sensor sensitivity while using relatively high doping levels (5 × 1019 atoms cm-3). The fabricated sensors have a gauge factor about three to four times higher compared to conventional thin-foil strain gauges.

Rationally Designed Sensing Selectivity and Sensitivity of an Aerolysin Nanopore via Site-Directed Mutagenesis.

PubMed

Wang, Ya-Qian; Cao, Chan; Ying, Yi-Lun; Li, Shuang; Wang, Ming-Bo; Huang, Jin; Long, Yi-Tao

2018-04-27

Selectivity and sensitivity are two key parameters utilized to describe the performance of a sensor. In order to investigate selectivity and sensitivity of the aerolysin nanosensor, we manipulated its surface charge at different locations via single site-directed mutagenesis. To study the selectivity, we replaced the positively charged R220 at the entrance of the pore with negatively charged glutamic acid, resulting in barely no current blockages for sensing negatively charged oligonucleotides. For the sensitivity, we substituted the positively charged lumen-exposed amino acid K238 located at trans-ward third of the β-barrel stem with glutamic acid. This leads to a surprisingly longer duration time at +140 mV, which is about 20 times slower in translocation speed for Poly(dA) 4 compared to that of wild-type aerolysin, indicating the stronger pore-analyte interactions and enhanced sensitivity. Therefore, it is both feasible and understandable to rationally design confined biological nanosensors for single molecule detection with high selectivity and sensitivity.

Does design matter? Systematic evaluation of the impact of analytical choices on effect estimates in observational studies

PubMed Central

Ryan, Patrick B.; Schuemie, Martijn

2013-01-01

Background: Clinical studies that use observational databases, such as administrative claims and electronic health records, to evaluate the effects of medical products have become commonplace. These studies begin by selecting a particular study design, such as a case control, cohort, or self-controlled design, and different authors can and do choose different designs for the same clinical question. Furthermore, published papers invariably report the study design but do not discuss the rationale for the specific choice. Studies of the same clinical question with different designs, however, can generate different results, sometimes with strikingly different implications. Even within a specific study design, authors make many different analytic choices and these too can profoundly impact results. In this paper, we systematically study heterogeneity due to the type of study design and due to analytic choices within study design. Methods and findings: We conducted our analysis in 10 observational healthcare databases but mostly present our results in the context of the GE Centricity EMR database, an electronic health record database containing data for 11.2 million lives. We considered the impact of three different study design choices on estimates of associations between bisphosphonates and four particular health outcomes for which there is no evidence of an association. We show that applying alternative study designs can yield discrepant results, in terms of direction and significance of association. We also highlight that while traditional univariate sensitivity analysis may not show substantial variation, systematic assessment of all analytical choices within a study design can yield inconsistent results ranging from statistically significant decreased risk to statistically significant increased risk. Our findings show that clinical studies using observational databases can be sensitive both to study design choices and to specific analytic choices within study design. Conclusion: More attention is needed to consider how design choices may be impacting results and, when possible, investigators should examine a wide array of possible choices to confirm that significant findings are consistently identified. PMID:25083251

Design optimization of condenser microphone: a design of experiment perspective.

PubMed

Tan, Chee Wee; Miao, Jianmin

2009-06-01

A well-designed condenser microphone backplate is very important in the attainment of good frequency response characteristics--high sensitivity and wide bandwidth with flat response--and low mechanical-thermal noise. To study the design optimization of the backplate, a 2(6) factorial design with a single replicate, which consists of six backplate parameters and four responses, has been undertaken on a comprehensive condenser microphone model developed by Zuckerwar. Through the elimination of insignificant parameters via normal probability plots of the effect estimates, the projection of an unreplicated factorial design into a replicated one can be performed to carry out an analysis of variance on the factorial design. The air gap and slot have significant effects on the sensitivity, mechanical-thermal noise, and bandwidth while the slot/hole location interaction has major influence over the latter two responses. An organized and systematic approach of designing the backplate is summarized.

Experimental Investigation of a Piezo-Optical Transducer for Highly Sensitive Strain Gauges

NASA Astrophysics Data System (ADS)

Paulish, A. G.; Zagubisalo, P. S.; Barakov, V. N.; Pavlov, M. A.

2018-03-01

The characteristics of a piezo-optical transducer of a new design with high strain sensitivity at compact size have been studied.The original form of the photoelastic element provides a considerable increase in the stress in its working area at a given external force, resulting in an increase in the sensitivity of the transducer. The main characteristics of the transducer were measured using a specially designed device. The strain at a given applied force was calculated using a developed mathematical model of the transducer. As a result, the sensitivity to the relative strain was Δ x/ x=3 · 10-10, the dynamic range was at least four orders of magnitude higher and the gauge factor three orders of magnitude higher than those of strain-resistive gauges.

Impact of longitudinal flying qualities upon the design of a transport with active controls

NASA Technical Reports Server (NTRS)

Sliwa, S. M.

1980-01-01

Direct constrained parameter optimization was used to optimally size a medium range transport for minimum direct operating cost. Several stability and control constraints were varied to study the sensitivity of the configuration to specifying the unaugmented flying qualities of transports designed with relaxed static stability. Additionally, a number of handling quality related design constants were studied with respect to their impact to the design.

Buckling Design and Imperfection Sensitivity of Sandwich Composite Launch-Vehicle Shell Structures

NASA Technical Reports Server (NTRS)

Schultz, Marc R.; Sleight, David W.; Myers, David E.; Waters, W. Allen, Jr.; Chunchu, Prasad B.; Lovejoy, Andrew W.; Hilburger, Mark W.

2016-01-01

Composite materials are increasingly being considered and used for launch-vehicle structures. For shell structures, such as interstages, skirts, and shrouds, honeycomb-core sandwich composites are often selected for their structural efficiency. Therefore, it is becoming increasingly important to understand the structural response, including buckling, of sandwich composite shell structures. Additionally, small geometric imperfections can significantly influence the buckling response, including considerably reducing the buckling load, of shell structures. Thus, both the response of the theoretically perfect structure and the buckling imperfection sensitivity must be considered during the design of such structures. To address the latter, empirically derived design factors, called buckling knockdown factors (KDFs), were developed by NASA in the 1960s to account for this buckling imperfection sensitivity during design. However, most of the test-article designs used in the development of these recommendations are not relevant to modern launch-vehicle constructions and material systems, and in particular, no composite test articles were considered. Herein, a two-part study on composite sandwich shells to (1) examine the relationship between the buckling knockdown factor and the areal mass of optimized designs, and (2) to interrogate the imperfection sensitivity of those optimized designs is presented. Four structures from recent NASA launch-vehicle development activities are considered. First, designs optimized for both strength and stability were generated for each of these structures using design optimization software and a range of buckling knockdown factors; it was found that the designed areal masses varied by between 6.1% and 19.6% over knockdown factors ranging from 0.6 to 0.9. Next, the buckling imperfection sensitivity of the optimized designs is explored using nonlinear finite-element analysis and the as-measured shape of a large-scale composite cylindrical shell. When compared with the current buckling design recommendations, the results suggest that the current recommendations are overly conservative and that the development of new recommendations could reduce the acreage areal mass of many composite sandwich shell designs by between 4% and 19%, depending on the structure.

Design and synthesis study of the thermo-sensitive poly (N-vinylpyrrolidone-b- N, N-diethylacrylamide).

PubMed

Zhang, Xiayun; Yang, Zhongduo; Xie, Dengmin; Liu, Donglei; Chen, Zhenbin; Li, Ke; Li, Zhizhong; Tichnell, Brandon; Liu, Zhen

2018-01-01

The reversible addition fragmentation chain transfer (RAFT) polymerization method was adopted here to prepare a series of thermo-sensitive copolymers, poly (N,N-diethyl- acrylamide-b-N-vinylpyrrolidone). Their structures, molecular weight distribution and temperature sensitivity performances were characterized by the nuclear magnetic resonance ( 1 HNMR), the gel permeation chromatography (GPC) and the fluorescence spectrophotometer, respectively. It has been identified that the synthesis reaction of the block copolymer was living polymerization. The thermo-sensitivity study suggested that N-vinylpyrrolidone (NVP), played a key role on the lower critical solution temperature (LCST) performance.

A parametric study of motor starting for a 2- to 10-kilowatt Brayton power system

NASA Technical Reports Server (NTRS)

Cantoni, D. A.

1971-01-01

A study of the motor starting of a Brayton cycle power system was conducted to provide estimates of system sensitivity to several controllable parameters. These sensitivity estimates were used as a basis for selection of an optimum motor-start scheme to be implemented on the 2- to 10-kilowatt Brayton power system designed and presently under test. The studies were conducted with an analog simulation of the Brayton power system and covered a range of frequencies from 400 Hz (33 percent design) to 1200 Hz (design), voltage-to-frequency ratios of 0.050 (50 percent design) to 0.100 (design), turbine-inlet temperatures of 800 K (1440 R, 70 percent design) to 1140 K (2060 deg R, design), and prestart pressure levels of 14.5 psia to 29.0 psia. These studies have shown the effect of selected system variables on motor starting. The final selection of motor-start variables can therefore be made on the basis of motor-start inverter complexity, battery size and weight, desired steady-state pressure level after startup, and other operational limitations. In general, the study showed the time required for motor starting to be inversely proportional to motor frequency, voltage, turbine-inlet temperature, and pressure level. An increase in any of these parameters decreases startup time.

Sensitivity analysis for axis rotation diagrid structural systems according to brace angle changes

NASA Astrophysics Data System (ADS)

Yang, Jae-Kwang; Li, Long-Yang; Park, Sung-Soo

2017-10-01

General regular shaped diagrid structures can express diverse shapes because braces are installed along the exterior faces of the structures and the structures have no columns. However, since irregular shaped structures have diverse variables, studies to assess behaviors resulting from various variables are continuously required to supplement the imperfections related to such variables. In the present study, materials elastic modulus and yield strength were selected as variables for strength that would be applied to diagrid structural systems in the form of Twisters among the irregular shaped buildings classified by Vollers and that affect the structural design of these structural systems. The purpose of this study is to conduct sensitivity analysis for axial rotation diagrid structural systems according to changes in brace angles in order to identify the design variables that have relatively larger effects and the tendencies of the sensitivity of the structures according to changes in brace angles and axial rotation angles.

Aggressive Behavior between Siblings and the Development of Externalizing Problems: Evidence from a Genetically Sensitive Study

ERIC Educational Resources Information Center

Natsuaki, Misaki N.; Ge, Xiaojia; Reiss, David; Neiderhiser, Jenae M.

2009-01-01

This study investigated the prospective links between sibling aggression and the development of externalizing problems using a multilevel modeling approach with a genetically sensitive design. The sample consisted of 780 adolescents (390 sibling pairs) who participated in 2 waves of the Nonshared Environment in Adolescent Development project.…

Axial compressor blade design for desensitization of aerodynamic performance and stability to tip clearance

NASA Astrophysics Data System (ADS)

Erler, Engin

Tip clearance flow is the flow through the clearance between the rotor blade tip and the shroud of a turbomachine, such as compressors and turbines. This flow is driven by the pressure difference across the blade (aerodynamic loading) in the tip region and is a major source of loss in performance and aerodynamic stability in axial compressors of modern aircraft engines. An increase in tip clearance, either temporary due to differential radial expansion between the blade and the shroud during transient operation or permanent due to engine wear or manufacturing tolerances on small blades, increases tip clearance flow and results in higher fuel consumption and higher risk of engine surge. A compressor design that can reduce the sensitivity of its performance and aerodynamic stability to tip clearance increase would have a major impact on short and long-term engine performance and operating envelope. While much research has been carried out on improving nominal compressor performance, little had been done on desensitization to tip clearance increase beyond isolated observations that certain blade designs such as forward chordwise sweep, seem to be less sensitive to tip clearance size increase. The current project aims to identify through a computational study the flow features and associated mechanisms that reduces sensitivity of axial compressor rotors to tip clearance size and propose blade design strategies that can exploit these results. The methodology starts with the design of a reference conventional axial compressor rotor followed by a parametric study with variations of this reference design through modification of the camber line and of the stacking line of blade profiles along the span. It is noted that a simple desensitization method would be to reduce the aerodynamic loading of the blade tip which would reduce the tip clearance flow and its proportional contribution to performance loss. However, with the larger part of the work on the flow done in this region, this approach would entail a nominal performance penalty. Therefore, the chosen rotor design philosophy aims to keep the spanwise loading constant to avoid trading performance for desensitization. The rotor designs that resulted from this exercise are simulated in ANSYS CFX at different tip clearance sizes. The change in their performance with respect to tip clearance size (sensitivity) is compared both on an integral level in terms of pressure ratio and adiabatic efficiency, as well as on a detailed level in terms of aerodynamic losses and blockage associated with tip clearance flow. The sensitivity of aerodynamic stability is evaluated either directly through the simulations of the rotor characteristics up to the stall point (expensive in time and resources) for a few designs or indirectly through the position of the interface between the incoming and tip clearance flow with respect to the rotor leading edge plane. The latter approach is based on a generally observed stall criteria in modern axial compressors. The rotor designs are then assessed according to their sensitivity in comparison to that of the reference rotor design to detect features that can explain the trend in sensitivity to tip clearance size. These features can then be validated and the associated flow mechanisms explained through numerical simulations and modelling. Analysis of the database from the rotor parametric study shows that the observed trend in sensitivity cannot be explained by the shifting of the aerodynamic loading along the blade chord, as initially hypothesized based on the literature review. Instead, two flow features are found to reduce sensitivity of performance and stability to tip clearance, namely an increase in incoming meridional momentum in the tip region and a reduction/elimination of double leakage flow. Double leakage flow is the flow that exits the tip clearance of one blade and proceeds into the clearance of the adjacent blade rather than convecting downstream out of the local blade passage. These flow features are isolated and validated based on the reference rotor design through changes in the inlet total pressure condition to alter incoming flow momentum and blade number count to change double leakage rate. In terms of flow mechanism, double leakage is shown to be detrimental to performance and stability, and its proportional increase with tip clearance size explains the sensitivity increase in the presence of double leakage and, conversely, the desensitization effect of reducing or eliminating double leakage. The increase in incoming meridional momentum in the tip region reduces sensitivity to tip clearance through its reduction of double leakage as well as through improved mixing with tip clearance flow, as demonstrated by an analytical model without double leakage flow. The above results imply that any blade design strategy that exploits the two desensitizing flow features would reduce the performance and stability sensitivity to tip clearance size. The increase of the incoming meridional momentum can be achieved through forward chordwise sweep of the blade. The reduction of double leakage without changing blade pitch can be obtained by decreasing the blade stagger angle in the tip region. Examples of blade designs associated with these strategies are shown through CFX simulations to be successful in reducing sensitivity to tip clearance size.

Augmented Cross-Sectional Studies with Abbreviated Follow-up for Estimating HIV Incidence

PubMed Central

Claggett, B.; Lagakos, S.W.; Wang, R.

2011-01-01

Summary Cross-sectional HIV incidence estimation based on a sensitive and less-sensitive test offers great advantages over the traditional cohort study. However, its use has been limited due to concerns about the false negative rate of the less-sensitive test, reflecting the phenomenon that some subjects may remain negative permanently on the less-sensitive test. Wang and Lagakos (2010) propose an augmented cross-sectional design which provides one way to estimate the size of the infected population who remain negative permanently and subsequently incorporate this information in the cross-sectional incidence estimator. In an augmented cross-sectional study, subjects who test negative on the less-sensitive test in the cross-sectional survey are followed forward for transition into the nonrecent state, at which time they would test positive on the less-sensitive test. However, considerable uncertainty exists regarding the appropriate length of follow-up and the size of the infected population who remain nonreactive permanently to the less-sensitive test. In this paper, we assess the impact of varying follow-up time on the resulting incidence estimators from an augmented cross-sectional study, evaluate the robustness of cross-sectional estimators to assumptions about the existence and the size of the subpopulation who will remain negative permanently, and propose a new estimator based on abbreviated follow-up time (AF). Compared to the original estimator from an augmented cross-sectional study, the AF Estimator allows shorter follow-up time and does not require estimation of the mean window period, defined as the average time between detectability of HIV infection with the sensitive and less-sensitive tests. It is shown to perform well in a wide range of settings. We discuss when the AF Estimator would be expected to perform well and offer design considerations for an augmented cross-sectional study with abbreviated follow-up. PMID:21668904

Augmented cross-sectional studies with abbreviated follow-up for estimating HIV incidence.

PubMed

Claggett, B; Lagakos, S W; Wang, R

2012-03-01

Cross-sectional HIV incidence estimation based on a sensitive and less-sensitive test offers great advantages over the traditional cohort study. However, its use has been limited due to concerns about the false negative rate of the less-sensitive test, reflecting the phenomenon that some subjects may remain negative permanently on the less-sensitive test. Wang and Lagakos (2010, Biometrics 66, 864-874) propose an augmented cross-sectional design that provides one way to estimate the size of the infected population who remain negative permanently and subsequently incorporate this information in the cross-sectional incidence estimator. In an augmented cross-sectional study, subjects who test negative on the less-sensitive test in the cross-sectional survey are followed forward for transition into the nonrecent state, at which time they would test positive on the less-sensitive test. However, considerable uncertainty exists regarding the appropriate length of follow-up and the size of the infected population who remain nonreactive permanently to the less-sensitive test. In this article, we assess the impact of varying follow-up time on the resulting incidence estimators from an augmented cross-sectional study, evaluate the robustness of cross-sectional estimators to assumptions about the existence and the size of the subpopulation who will remain negative permanently, and propose a new estimator based on abbreviated follow-up time (AF). Compared to the original estimator from an augmented cross-sectional study, the AF estimator allows shorter follow-up time and does not require estimation of the mean window period, defined as the average time between detectability of HIV infection with the sensitive and less-sensitive tests. It is shown to perform well in a wide range of settings. We discuss when the AF estimator would be expected to perform well and offer design considerations for an augmented cross-sectional study with abbreviated follow-up. © 2011, The International Biometric Society.

Design sensitivity analysis with Applicon IFAD using the adjoint variable method

NASA Technical Reports Server (NTRS)

Frederick, Marjorie C.; Choi, Kyung K.

1984-01-01

A numerical method is presented to implement structural design sensitivity analysis using the versatility and convenience of existing finite element structural analysis program and the theoretical foundation in structural design sensitivity analysis. Conventional design variables, such as thickness and cross-sectional areas, are considered. Structural performance functionals considered include compliance, displacement, and stress. It is shown that calculations can be carried out outside existing finite element codes, using postprocessing data only. That is, design sensitivity analysis software does not have to be imbedded in an existing finite element code. The finite element structural analysis program used in the implementation presented is IFAD. Feasibility of the method is shown through analysis of several problems, including built-up structures. Accurate design sensitivity results are obtained without the uncertainty of numerical accuracy associated with selection of a finite difference perturbation.

The Science and Design of the AGIS Observatory

NASA Astrophysics Data System (ADS)

Schroedter, Martin

2010-02-01

The AGIS observatory is a next-generation array of imaging atmospheric Cherenkov telescopes (IACTs) for gamma-ray astronomy between 100 GeV and 100 TeV. The AGIS observatory is the next logical step in high energy gamma-ray astronomy, offering improved angular resolution and sensitivity compared to FERMI, and overlapping the high energy end of FERMI's sensitivity band. The baseline AGIS observatory will employ an array of 36 Schwarzschild-Couder IACTs in combination with a highly pixelated (0.05^o diameter) camera. The instrument is designed to provide millicrab sensitivity over a wide (8^o diameter) field of view, allowing both deep studies of faint point sources as well as efficient mapping of the Galactic plane and extended sources. I will describe science drivers behind the AGIS observatory and the design and status of the project. )

The Science and Design of the AGIS Observatory

NASA Astrophysics Data System (ADS)

Falcone, Abraham; Aliu, E.; Arlen, T.; Benbow, W.; Buckley, J.; Bugaev, S.; Byrum, K.; Ciupik, L.; Coppi, P.; Digel, S.; Drake, G.; Finley, J.; Fortson, L.; Franco, J.; Funk, S.; Guarino, V.; Gyuk, G.; Hanna, D.; Hiriart, D.; Humensky, B.; Holder, J.; Kaaret, P.; Karlsson, N.; Kieda, D.; Konopelko, A.; Krawczynski, H.; Krennrich, F.; LeBohec, S.; Maier, G.; Mukherjee, R.; Ong, R.; Otte, N.; Pareschi, G.; Pohl, M.; Quinn, J.; Ramsey, B.; Romani, R.; Rovero, A. C.; Schroedter, M.; Sinnis, C.; Slane, P.; Smith, A.; Swordy, S.; Tajima, H.; Vassiliev, V.; Wagner, R.; Wakely, S. P.; Weekes, T. C.; Weinstein, A.; Williams, D.

2010-01-01

The AGIS observatory is a next-generation array of imaging atmospheric Cherenkov telescopes (IACTs) for gamma-ray astronomy between 100GeV and 100 TeV. The AGIS observatory is the next logical step in high energy gamma-ray astronomy, offering improved angular resolution and sensitivity compared to FERMI, and overlapping the high energy end of FERMI's sensitivity band. The baseline AGIS observatory will employ an array of 36 Schwarzschild-Couder IACTs in combination with a highly pixelated (0.05 degree/pixel) camera. The instrument is designed to provide millicrab sensitivity over a wide (8 degree diameter) field of view, allowing both deep studies of faint point sources as well as efficient mapping of the Galactic plane and extended sources. This presentation will include a description of science drivers behind the AGIS observatory and the design and status of the project.

What makes a good home-based nocturnal seizure detector? A value sensitive design.

PubMed

van Andel, Judith; Leijten, Frans; van Delden, Hans; van Thiel, Ghislaine

2015-01-01

A device for the in-home detection of nocturnal seizures is currently being developed in the Netherlands, to improve care for patients with severe epilepsy. It is recognized that the design of medical technology is not value neutral: perspectives of users and developers are influential in design, and design choices influence these perspectives. However, during development processes, these influences are generally ignored and value-related choices remain implicit and poorly argued for. In the development process of the seizure detector we aimed to take values of all stakeholders into consideration. Therefore, we performed a parallel ethics study, using "value sensitive design." Analysis of stakeholder communication (in meetings and e-mail messages) identified five important values, namely, health, trust, autonomy, accessibility, and reliability. Stakeholders were then asked to give feedback on the choice of these values and how they should be interpreted. In a next step, the values were related to design choices relevant for the device, and then the consequences (risks and benefits) of these choices were investigated. Currently the process of design and testing of the device is still ongoing. The device will be validated in a trial in which the identified consequences of design choices are measured as secondary endpoints. Value sensitive design methodology is feasible for the development of new medical technology and can help designers substantiate the choices in their design.

Submersible Aircraft Concept Design Study - Amendment 1. Additional Assessment of Design Risks & Sensitivities within the Original Study, and an Initial Assessment of Key Control Aspects

DTIC Science & Technology

2011-02-01

http://www.redhammer.se/tornado/index.html (3) Aircraft Design: A Conceptual Approach, Daniel P. Raymer , AIAA, 1992 (4) (5) Moran, J., Computational...Fluid Dynamics, Wiley & Sons, 1984. Notes on the Stability and Control of Tailless Airplanes, Robert T. Jones, NACA Technical Note No.837, December

Balancing Methodological Rigor and the Needs of Research Participants: A Debate on Alternative Approaches to Sensitive Research.

PubMed

Chan, T M Simon; Teram, Eli; Shaw, Ian

2017-01-01

Despite growing consideration of the needs of research participants in studies related to sensitive issues, discussions of alternative ways to design sensitive research are scarce. Structured as an exchange between two researchers who used different approaches in their studies with childhood sexual abuse survivors, in this article, we seek to advance understanding of methodological and ethical issues in designing sensitive research. The first perspective, which is termed protective, promotes the gradual progression of participants from a treatment phase into a research phase, with the ongoing presence of a researcher and a social worker in both phases. In the second perspective, which is termed minimalist, we argue for clear boundaries between research and treatment processes, limiting the responsibility of researchers to ensuring that professional support is available to participants who experience emotional difficulties. Following rebuttals, lessons are drawn for ethical balancing between methodological rigor and the needs of participants. © The Author(s) 2015.

Examining the Independent Contribution of Prosodic Sensitivity to Word Reading and Spelling in Early Readers

ERIC Educational Resources Information Center

Holliman, A. J.; Gutiérrez Palma, N.; Critten, S.; Wood, C.; Cunnane, H.; Pillinger, C.

2017-01-01

This study was designed to examine the independent contribution of prosodic sensitivity--the rhythmic patterning of speech-to word reading and spelling in a sample of early readers. Ninety-three English-speaking children aged 5-6 years old (M = 69.28 months, SD = 3.67) were assessed for their prosodic sensitivity, vocabulary knowledge,…

Influence of operating conditions on the optimum design of electric vehicle battery cooling plates

NASA Astrophysics Data System (ADS)

Jarrett, Anthony; Kim, Il Yong

2014-01-01

The efficiency of cooling plates for electric vehicle batteries can be improved by optimizing the geometry of internal fluid channels. In practical operation, a cooling plate is exposed to a range of operating conditions dictated by the battery, environment, and driving behaviour. To formulate an efficient cooling plate design process, the optimum design sensitivity with respect to each boundary condition is desired. This determines which operating conditions must be represented in the design process, and therefore the complexity of designing for multiple operating conditions. The objective of this study is to determine the influence of different operating conditions on the optimum cooling plate design. Three important performance measures were considered: temperature uniformity, mean temperature, and pressure drop. It was found that of these three, temperature uniformity was most sensitive to the operating conditions, especially with respect to the distribution of the input heat flux, and also to the coolant flow rate. An additional focus of the study was the distribution of heat generated by the battery cell: while it is easier to assume that heat is generated uniformly, by using an accurate distribution for design optimization, this study found that cooling plate performance could be significantly improved.

Precision of Sensitivity in the Design Optimization of Indeterminate Structures

NASA Technical Reports Server (NTRS)

Patnaik, Surya N.; Pai, Shantaram S.; Hopkins, Dale A.

2006-01-01

Design sensitivity is central to most optimization methods. The analytical sensitivity expression for an indeterminate structural design optimization problem can be factored into a simple determinate term and a complicated indeterminate component. Sensitivity can be approximated by retaining only the determinate term and setting the indeterminate factor to zero. The optimum solution is reached with the approximate sensitivity. The central processing unit (CPU) time to solution is substantially reduced. The benefit that accrues from using the approximate sensitivity is quantified by solving a set of problems in a controlled environment. Each problem is solved twice: first using the closed-form sensitivity expression, then using the approximation. The problem solutions use the CometBoards testbed as the optimization tool with the integrated force method as the analyzer. The modification that may be required, to use the stiffener method as the analysis tool in optimization, is discussed. The design optimization problem of an indeterminate structure contains many dependent constraints because of the implicit relationship between stresses, as well as the relationship between the stresses and displacements. The design optimization process can become problematic because the implicit relationship reduces the rank of the sensitivity matrix. The proposed approximation restores the full rank and enhances the robustness of the design optimization method.

The Negative Affect Hypothesis of Noise Sensitivity

PubMed Central

Shepherd, Daniel; Heinonen-Guzejev, Marja; Heikkilä, Kauko; Dirks, Kim N.; Hautus, Michael J.; Welch, David; McBride, David

2015-01-01

Some studies indicate that noise sensitivity is explained by negative affect, a dispositional tendency to negatively evaluate situations and the self. Individuals high in such traits may report a greater sensitivity to other sensory stimuli, such as smell, bright light and pain. However, research investigating the relationship between noise sensitivity and sensitivity to stimuli associated with other sensory modalities has not always supported the notion of a common underlying trait, such as negative affect, driving them. Additionally, other explanations of noise sensitivity based on cognitive processes have existed in the clinical literature for over 50 years. Here, we report on secondary analyses of pre-existing laboratory (n = 74) and epidemiological (n = 1005) data focusing on the relationship between noise sensitivity to and annoyance with a variety of olfactory-related stimuli. In the first study a correlational design examined the relationships between noise sensitivity, noise annoyance, and perceptual ratings of 16 odors. The second study sought differences between mean noise and air pollution annoyance scores across noise sensitivity categories. Results from both analyses failed to support the notion that, by itself, negative affectivity explains sensitivity to noise. PMID:25993104

A PDE Sensitivity Equation Method for Optimal Aerodynamic Design

NASA Technical Reports Server (NTRS)

Borggaard, Jeff; Burns, John

1996-01-01

The use of gradient based optimization algorithms in inverse design is well established as a practical approach to aerodynamic design. A typical procedure uses a simulation scheme to evaluate the objective function (from the approximate states) and its gradient, then passes this information to an optimization algorithm. Once the simulation scheme (CFD flow solver) has been selected and used to provide approximate function evaluations, there are several possible approaches to the problem of computing gradients. One popular method is to differentiate the simulation scheme and compute design sensitivities that are then used to obtain gradients. Although this black-box approach has many advantages in shape optimization problems, one must compute mesh sensitivities in order to compute the design sensitivity. In this paper, we present an alternative approach using the PDE sensitivity equation to develop algorithms for computing gradients. This approach has the advantage that mesh sensitivities need not be computed. Moreover, when it is possible to use the CFD scheme for both the forward problem and the sensitivity equation, then there are computational advantages. An apparent disadvantage of this approach is that it does not always produce consistent derivatives. However, for a proper combination of discretization schemes, one can show asymptotic consistency under mesh refinement, which is often sufficient to guarantee convergence of the optimal design algorithm. In particular, we show that when asymptotically consistent schemes are combined with a trust-region optimization algorithm, the resulting optimal design method converges. We denote this approach as the sensitivity equation method. The sensitivity equation method is presented, convergence results are given and the approach is illustrated on two optimal design problems involving shocks.

Design optimization for a wearable, gamma-ray and neutron sensitive, detector array with directionality estimation

NASA Astrophysics Data System (ADS)

Ayaz-Maierhafer, Birsen; Britt, Carl G.; August, Andrew J.; Qi, Hairong; Seifert, Carolyn E.; Hayward, Jason P.

2017-10-01

In this study, we report on a constrained optimization and tradeoff study of a hybrid, wearable detector array having directional sensing based upon gamma-ray occlusion. One resulting design uses CLYC detectors while the second feasibility design involves the coupling of gamma-ray-sensitive CsI scintillators and a rubber LiCaAlF6 (LiCAF) neutron detector. The detector systems' responses were investigated through simulation as a function of angle in a two-dimensional plane. The expected total counts, peak-to-total ratio, directionality performance, and detection of 40 K for accurate gain stabilization were considered in the optimization. Source directionality estimation was investigated using Bayesian algorithms. Gamma-ray energies of 122 keV, 662 keV, and 1332 keV were considered. The equivalent neutron capture response compared with 3 He was also investigated for both designs.

High S/N Ratio Slotted Step Piezoresistive Microcantilever Designs for Biosensors

PubMed Central

Ansari, Mohd Zahid; Cho, Chongdu

2013-01-01

This study proposes new microcantilever designs in slotted step configuration to improve the S/N ratio of surface stress-based sensors used in physical, chemical, biochemical and biosensor applications. The cantilevers are made of silicon dioxide with a u-shaped silicon piezoresistor in p-doped. The cantilever step length and piezoresistor length is varied along with the operating voltage to characterise the surface stress sensitivity and thermal drifting sensitivity of the cantilevers when used as immunosensor. The numerical analysis is performed using ANSYS Multiphysics. Results show the surface stress sensitivity and the S/N ratio of the slotted step cantilevers is improved by more than 32% and 22%, respectively, over its monolithic counterparts. PMID:23535637

High S/N ratio slotted step piezoresistive microcantilever designs for biosensors.

PubMed

Ansari, Mohd Zahid; Cho, Chongdu

2013-03-26

This study proposes new microcantilever designs in slotted step configuration to improve the S/N ratio of surface stress-based sensors used in physical, chemical, biochemical and biosensor applications. The cantilevers are made of silicon dioxide with a u-shaped silicon piezoresistor in p-doped. The cantilever step length and piezoresistor length is varied along with the operating voltage to characterise the surface stress sensitivity and thermal drifting sensitivity of the cantilevers when used as immunosensor. The numerical analysis is performed using ANSYS Multiphysics. Results show the surface stress sensitivity and the S/N ratio of the slotted step cantilevers is improved by more than 32% and 22%, respectively, over its monolithic counterparts.

Netlist Oriented Sensitivity Evaluation (NOSE)

DTIC Science & Technology

2017-03-01

developing methodologies to assess sensitivities of alternative chip design netlist implementations. The research is somewhat foundational in that such...Netlist-Oriented Sensitivity Evaluation (NOSE) project was to develop methodologies to assess sensitivities of alternative chip design netlist...analysis to devise a methodology for scoring the sensitivity of circuit nodes in a netlist and thus providing the raw data for any meaningful

Measuring Cognitive Load during Simulation-Based Psychomotor Skills Training: Sensitivity of Secondary-Task Performance and Subjective Ratings

ERIC Educational Resources Information Center

Haji, Faizal A.; Khan, Rabia; Regehr, Glenn; Drake, James; de Ribaupierre, Sandrine; Dubrowski, Adam

2015-01-01

As interest in applying cognitive load theory (CLT) to the study and design of pedagogic and technological approaches in healthcare simulation grows, suitable measures of cognitive load (CL) are needed. Here, we report a two-phased study investigating the sensitivity of subjective ratings of mental effort (SRME) and secondary-task performance…

Concept Study of Optical Configurations for High-Frequency Telescope for LiteBIRD

NASA Astrophysics Data System (ADS)

Hasebe, T.; Kashima, S.; Ade, P. A. R.; Akiba, Y.; Alonso, D.; Arnold, K.; Aumont, J.; Baccigalupi, C.; Barron, D.; Basak, S.; Beckman, S.; Borrill, J.; Boulanger, F.; Bucher, M.; Calabrese, E.; Chinone, Y.; Cho, H.-M.; Cukierman, A.; Curtis, D. W.; de Haan, T.; Dobbs, M.; Dominjon, A.; Dotani, T.; Duband, L.; Ducout, A.; Dunkley, J.; Duval, J. M.; Elleflot, T.; Eriksen, H. K.; Errard, J.; Fischer, J.; Fujino, T.; Funaki, T.; Fuskeland, U.; Ganga, K.; Goeckner-Wald, N.; Grain, J.; Halverson, N. W.; Hamada, T.; Hasegawa, M.; Hattori, K.; Hattori, M.; Hayes, L.; Hazumi, M.; Hidehira, N.; Hill, C. A.; Hilton, G.; Hubmayr, J.; Ichiki, K.; Iida, T.; Imada, H.; Inoue, M.; Inoue, Y.; Irwin, K. D.; Ishino, H.; Jeong, O.; Kanai, H.; Kaneko, D.; Katayama, N.; Kawasaki, T.; Kernasovskiy, S. A.; Keskitalo, R.; Kibayashi, A.; Kida, Y.; Kimura, K.; Kisner, T.; Kohri, K.; Komatsu, E.; Komatsu, K.; Kuo, C. L.; Kurinsky, N. A.; Kusaka, A.; Lazarian, A.; Lee, A. T.; Li, D.; Linder, E.; Maffei, B.; Mangilli, A.; Maki, M.; Matsumura, T.; Matsuura, S.; Meilhan, D.; Mima, S.; Minami, Y.; Mitsuda, K.; Montier, L.; Nagai, M.; Nagasaki, T.; Nagata, R.; Nakajima, M.; Nakamura, S.; Namikawa, T.; Naruse, M.; Nishino, H.; Nitta, T.; Noguchi, T.; Ogawa, H.; Oguri, S.; Okada, N.; Okamoto, A.; Okamura, T.; Otani, C.; Patanchon, G.; Pisano, G.; Rebeiz, G.; Remazeilles, M.; Richards, P. L.; Sakai, S.; Sakurai, Y.; Sato, Y.; Sato, N.; Sawada, M.; Segawa, Y.; Sekimoto, Y.; Seljak, U.; Sherwin, B. D.; Shimizu, T.; Shinozaki, K.; Stompor, R.; Sugai, H.; Sugita, H.; Suzuki, A.; Suzuki, J.; Tajima, O.; Takada, S.; Takaku, R.; Takakura, S.; Takatori, S.; Tanabe, D.; Taylor, E.; Thompson, K. L.; Thorne, B.; Tomaru, T.; Tomida, T.; Tomita, N.; Tristram, M.; Tucker, C.; Turin, P.; Tsujimoto, M.; Uozumi, S.; Utsunomiya, S.; Uzawa, Y.; Vansyngel, F.; Wehus, I. K.; Westbrook, B.; Willer, M.; Whitehorn, N.; Yamada, Y.; Yamamoto, R.; Yamasaki, N.; Yamashita, T.; Yoshida, M.

2018-05-01

The high-frequency telescope for LiteBIRD is designed with refractive and reflective optics. In order to improve sensitivity, this paper suggests the new optical configurations of the HFT which have approximately 7 times larger focal planes than that of the original design. The sensitivities of both the designs are compared, and the requirement of anti-reflection (AR) coating on the lens for the refractive option is derived. We also present the simulation result of a sub-wavelength AR structure on both surfaces of silicon, which shows a band-averaged reflection of 1.1-3.2% at 101-448 GHz.

Eliciting an antibody response against a recombinant TSH containing fusion protein.

PubMed

Mard-Soltani, Maysam; Rasaee, Mohamad Javad; Sheikhi, AbdolKarim; Hedayati, Mehdi

2017-01-01

Designing novel antigens to rise specific antibodies for Thyroid Stimulating Hormone (TSH) detection is of great significance. A novel fusion protein consisting of the C termini sequence of TSH beta subunit and a fusion sequence was designed and produced for rabbit immunization. Thereafter, the produced antibodies were purified and characterized for TSH detection. Our results indicate that the produced antibody is capable of sensitive and specific detection of TSH with low cross reactivity. This study underscores the applicability of designed fusion protein for specific and sensitive polyclonal antibody production and the importance of selecting an amenable region of the TSH for immunization.

Nonindependence and sensitivity analyses in ecological and evolutionary meta-analyses.

PubMed

Noble, Daniel W A; Lagisz, Malgorzata; O'dea, Rose E; Nakagawa, Shinichi

2017-05-01

Meta-analysis is an important tool for synthesizing research on a variety of topics in ecology and evolution, including molecular ecology, but can be susceptible to nonindependence. Nonindependence can affect two major interrelated components of a meta-analysis: (i) the calculation of effect size statistics and (ii) the estimation of overall meta-analytic estimates and their uncertainty. While some solutions to nonindependence exist at the statistical analysis stages, there is little advice on what to do when complex analyses are not possible, or when studies with nonindependent experimental designs exist in the data. Here we argue that exploring the effects of procedural decisions in a meta-analysis (e.g. inclusion of different quality data, choice of effect size) and statistical assumptions (e.g. assuming no phylogenetic covariance) using sensitivity analyses are extremely important in assessing the impact of nonindependence. Sensitivity analyses can provide greater confidence in results and highlight important limitations of empirical work (e.g. impact of study design on overall effects). Despite their importance, sensitivity analyses are seldom applied to problems of nonindependence. To encourage better practice for dealing with nonindependence in meta-analytic studies, we present accessible examples demonstrating the impact that ignoring nonindependence can have on meta-analytic estimates. We also provide pragmatic solutions for dealing with nonindependent study designs, and for analysing dependent effect sizes. Additionally, we offer reporting guidelines that will facilitate disclosure of the sources of nonindependence in meta-analyses, leading to greater transparency and more robust conclusions. © 2017 John Wiley & Sons Ltd.

Dakota, a multilevel parallel object-oriented framework for design optimization, parameter estimation, uncertainty quantification, and sensitivity analysis :

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adams, Brian M.; Ebeida, Mohamed Salah; Eldred, Michael S.

The Dakota (Design Analysis Kit for Optimization and Terascale Applications) toolkit provides a exible and extensible interface between simulation codes and iterative analysis methods. Dakota contains algorithms for optimization with gradient and nongradient-based methods; uncertainty quanti cation with sampling, reliability, and stochastic expansion methods; parameter estimation with nonlinear least squares methods; and sensitivity/variance analysis with design of experiments and parameter study methods. These capabilities may be used on their own or as components within advanced strategies such as surrogate-based optimization, mixed integer nonlinear programming, or optimization under uncertainty. By employing object-oriented design to implement abstractions of the key components requiredmore » for iterative systems analyses, the Dakota toolkit provides a exible and extensible problem-solving environment for design and performance analysis of computational models on high performance computers. This report serves as a user's manual for the Dakota software and provides capability overviews and procedures for software execution, as well as a variety of example studies.« less

Spacecraft design sensitivity for a disaster warning satellite system

NASA Technical Reports Server (NTRS)

Maloy, J. E.; Provencher, C. E.; Leroy, B. E.; Braley, R. C.; Shumaker, H. A.

1977-01-01

A disaster warning satellite (DWS) is described for warning the general public of impending natural catastrophes. The concept is responsive to NOAA requirements and maximizes the use of ATS-6 technology. Upon completion of concept development, the study was extended to establishing the sensitivity of the DWSS spacecraft power, weight, and cost to variations in both warning and conventional communications functions. The results of this sensitivity analysis are presented.

Multidisciplinary design optimization using multiobjective formulation techniques

NASA Technical Reports Server (NTRS)

Chattopadhyay, Aditi; Pagaldipti, Narayanan S.

1995-01-01

This report addresses the development of a multidisciplinary optimization procedure using an efficient semi-analytical sensitivity analysis technique and multilevel decomposition for the design of aerospace vehicles. A semi-analytical sensitivity analysis procedure is developed for calculating computational grid sensitivities and aerodynamic design sensitivities. Accuracy and efficiency of the sensitivity analysis procedure is established through comparison of the results with those obtained using a finite difference technique. The developed sensitivity analysis technique are then used within a multidisciplinary optimization procedure for designing aerospace vehicles. The optimization problem, with the integration of aerodynamics and structures, is decomposed into two levels. Optimization is performed for improved aerodynamic performance at the first level and improved structural performance at the second level. Aerodynamic analysis is performed by solving the three-dimensional parabolized Navier Stokes equations. A nonlinear programming technique and an approximate analysis procedure are used for optimization. The proceduredeveloped is applied to design the wing of a high speed aircraft. Results obtained show significant improvements in the aircraft aerodynamic and structural performance when compared to a reference or baseline configuration. The use of the semi-analytical sensitivity technique provides significant computational savings.

Design analysis of an MPI human functional brain scanner

PubMed Central

Mason, Erica E.; Cooley, Clarissa Z.; Cauley, Stephen F.; Griswold, Mark A.; Conolly, Steven M.; Wald, Lawrence L.

2017-01-01

MPI’s high sensitivity makes it a promising modality for imaging brain function. Functional contrast is proposed based on blood SPION concentration changes due to Cerebral Blood Volume (CBV) increases during activation, a mechanism utilized in fMRI studies. MPI offers the potential for a direct and more sensitive measure of SPION concentration, and thus CBV, than fMRI. As such, fMPI could surpass fMRI in sensitivity, enhancing the scientific and clinical value of functional imaging. As human-sized MPI systems have not been attempted, we assess the technical challenges of scaling MPI from rodent to human brain. We use a full-system MPI simulator to test arbitrary hardware designs and encoding practices, and we examine tradeoffs imposed by constraints that arise when scaling to human size as well as safety constraints (PNS and central nervous system stimulation) not considered in animal scanners, thereby estimating spatial resolutions and sensitivities achievable with current technology. Using a projection FFL MPI system, we examine coil hardware options and their implications for sensitivity and spatial resolution. We estimate that an fMPI brain scanner is feasible, although with reduced sensitivity (20×) and spatial resolution (5×) compared to existing rodent systems. Nonetheless, it retains sufficient sensitivity and spatial resolution to make it an attractive future instrument for studying the human brain; additional technical innovations can result in further improvements. PMID:28752130

Variance-Based Sensitivity Analysis to Support Simulation-Based Design Under Uncertainty

DOE PAGES

Opgenoord, Max M. J.; Allaire, Douglas L.; Willcox, Karen E.

2016-09-12

Sensitivity analysis plays a critical role in quantifying uncertainty in the design of engineering systems. A variance-based global sensitivity analysis is often used to rank the importance of input factors, based on their contribution to the variance of the output quantity of interest. However, this analysis assumes that all input variability can be reduced to zero, which is typically not the case in a design setting. Distributional sensitivity analysis (DSA) instead treats the uncertainty reduction in the inputs as a random variable, and defines a variance-based sensitivity index function that characterizes the relative contribution to the output variance as amore » function of the amount of uncertainty reduction. This paper develops a computationally efficient implementation for the DSA formulation and extends it to include distributions commonly used in engineering design under uncertainty. Application of the DSA method to the conceptual design of a commercial jetliner demonstrates how the sensitivity analysis provides valuable information to designers and decision-makers on where and how to target uncertainty reduction efforts.« less

Variance-Based Sensitivity Analysis to Support Simulation-Based Design Under Uncertainty

DOE Office of Scientific and Technical Information (OSTI.GOV)

Opgenoord, Max M. J.; Allaire, Douglas L.; Willcox, Karen E.

Sensitivity analysis plays a critical role in quantifying uncertainty in the design of engineering systems. A variance-based global sensitivity analysis is often used to rank the importance of input factors, based on their contribution to the variance of the output quantity of interest. However, this analysis assumes that all input variability can be reduced to zero, which is typically not the case in a design setting. Distributional sensitivity analysis (DSA) instead treats the uncertainty reduction in the inputs as a random variable, and defines a variance-based sensitivity index function that characterizes the relative contribution to the output variance as amore » function of the amount of uncertainty reduction. This paper develops a computationally efficient implementation for the DSA formulation and extends it to include distributions commonly used in engineering design under uncertainty. Application of the DSA method to the conceptual design of a commercial jetliner demonstrates how the sensitivity analysis provides valuable information to designers and decision-makers on where and how to target uncertainty reduction efforts.« less

Design, characterization, and sensitivity of the supernova trigger system at Daya Bay

NASA Astrophysics Data System (ADS)

Wei, Hanyu; Lebanowski, Logan; Li, Fei; Wang, Zhe; Chen, Shaomin

2016-02-01

Providing an early warning of galactic supernova explosions from neutrino signals is important in studying supernova dynamics and neutrino physics. A dedicated supernova trigger system has been designed and installed in the data acquisition system at Daya Bay and integrated into the worldwide Supernova Early Warning System (SNEWS). Daya Bay's unique feature of eight identically-designed detectors deployed in three separate experimental halls makes the trigger system naturally robust against cosmogenic backgrounds, enabling a prompt analysis of online triggers and a tight control of the false-alert rate. The trigger system is estimated to be fully sensitive to 1987A-type supernova bursts throughout most of the Milky Way. The significant gain in sensitivity of the eight-detector configuration over a mass-equivalent single detector is also estimated. The experience of this online trigger system is applicable to future projects with spatially distributed detectors.

Influence of Culture and Language Sensitive Physics on Science Attitude Enhancement

ERIC Educational Resources Information Center

Morales, Marie Paz E.

2015-01-01

The study critically explored how culture and language sensitive curriculum materials in physics improve Pangasinan learners' attitude towards science. Their cultural dimensions, epistemological beliefs, and views on integration of culture and language in the teaching and learning process determined their cultural preference or profile. Design and…

Radical Sensitivity Is the Key to Understanding Chinese Character Acquisition in Children

ERIC Educational Resources Information Center

Tong, Xiuhong; Tong, Xiuli; McBride, Catherine

2017-01-01

This study investigated Chinese children's development of sensitivity to positional (orthographic), phonological, and semantic cues of radicals in encoding novel Chinese characters. A newly designed picture-novel character mapping task, along with nonverbal reasoning ability, vocabulary, and Chinese character recognition were administered to 198…

Sensitivity Analysis of Hydraulic Head to Locations of Model Boundaries

DOE PAGES

Lu, Zhiming

2018-01-30

Sensitivity analysis is an important component of many model activities in hydrology. Numerous studies have been conducted in calculating various sensitivities. Most of these sensitivity analysis focus on the sensitivity of state variables (e.g. hydraulic head) to parameters representing medium properties such as hydraulic conductivity or prescribed values such as constant head or flux at boundaries, while few studies address the sensitivity of the state variables to some shape parameters or design parameters that control the model domain. Instead, these shape parameters are typically assumed to be known in the model. In this study, based on the flow equation, wemore » derive the equation (and its associated initial and boundary conditions) for sensitivity of hydraulic head to shape parameters using continuous sensitivity equation (CSE) approach. These sensitivity equations can be solved numerically in general or analytically in some simplified cases. Finally, the approach has been demonstrated through two examples and the results are compared favorably to those from analytical solutions or numerical finite difference methods with perturbed model domains, while numerical shortcomings of the finite difference method are avoided.« less

Sensitivity Analysis of Hydraulic Head to Locations of Model Boundaries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Zhiming

Sensitivity analysis is an important component of many model activities in hydrology. Numerous studies have been conducted in calculating various sensitivities. Most of these sensitivity analysis focus on the sensitivity of state variables (e.g. hydraulic head) to parameters representing medium properties such as hydraulic conductivity or prescribed values such as constant head or flux at boundaries, while few studies address the sensitivity of the state variables to some shape parameters or design parameters that control the model domain. Instead, these shape parameters are typically assumed to be known in the model. In this study, based on the flow equation, wemore » derive the equation (and its associated initial and boundary conditions) for sensitivity of hydraulic head to shape parameters using continuous sensitivity equation (CSE) approach. These sensitivity equations can be solved numerically in general or analytically in some simplified cases. Finally, the approach has been demonstrated through two examples and the results are compared favorably to those from analytical solutions or numerical finite difference methods with perturbed model domains, while numerical shortcomings of the finite difference method are avoided.« less

Economic evaluation of flying-qualities design criteria for a transport configured with relaxed static stability

NASA Technical Reports Server (NTRS)

Sliwa, S. M.

1980-01-01

Direct constrained parameter optimization was used to optimally size a medium range transport for minimum direct operating cost. Several stability and control constraints were varied to study the sensitivity of the configuration to specifying the unaugmented flying qualities of transports designed to take maximum advantage of relaxed static stability augmentation systems. Additionally, a number of handling qualities related design constants were studied with respect to their impact on the design.

Conditionally activating optical contrast agent with enhanced sensitivity via gold nanoparticle plasmon energy transfer: feasibility study.

PubMed

Kang, Kyung Aih; Wang, Jianting

2014-12-07

Molecular sensing/imaging utilizing fluorophores has been one of the most frequently used techniques in biomedical research. As for any molecular imaging techniques, fluorescence mediated sensing always seeks for greater specificity and sensitivity. Since fluorophores emit fluorescence while their electron energy state changes, manipulating the local electromagnetic field around the fluorophores may be a way to enhance the specificity and sensitivity. Gold nanoparticles (GNPs) are known to form a very strong electromagnetic field on their surface [i.e., surface plasmon field (SPF)], upon receiving photonic energy. The level of fluorescence change by GNP-SPF may range from complete quenching to extensive enhancement, depending upon the SPF strength, excitation and emission wavelengths, and quantum yield of the fluorophore. Here, we report a novel design that utilizes BOTH fluorescence quenching and enhancement abilities of the GNP in one single nano-entity, providing high specificity and sensitivity. The construct utilizes a specially designed molecular dual-spacer that places the fluorphore at the location with an appropriate GNP-SFP strength before and after exposed to the biomarker. A model system to test the concept was an optical signal mediator activated by urokinase-type plasminogen activator (uPA; breast cancer secreting enzyme). The resulting contrast agent shows less than 10% of the natural fluorescence but, in the presence of uPA, its fluorescence emission is triggered and emits its fluorescence approximately twice of the natural form. This study demonstrated that our novel design of an optical contrast agent can be conditionally activated with enhanced sensitivity, using both quenching and enhancement phenomena of fluorophores in the electromagnetic field of the appropriate strengths (in this case, locally generated by the GNP-SPF). This entity is similar to molecular beacon in terms of specificity but with greater sensitivity. In addition, it is not restricted to only DNA or RNA sensing but for any designs that cause the change in the distance between the fluorophore and GNP, upon the time of encountering biomarker of interest.

Design sensitivity analysis using EAL. Part 1: Conventional design parameters

NASA Technical Reports Server (NTRS)

Dopker, B.; Choi, Kyung K.; Lee, J.

1986-01-01

A numerical implementation of design sensitivity analysis of builtup structures is presented, using the versatility and convenience of an existing finite element structural analysis code and its database management system. The finite element code used in the implemenatation presented is the Engineering Analysis Language (EAL), which is based on a hybrid method of analysis. It was shown that design sensitivity computations can be carried out using the database management system of EAL, without writing a separate program and a separate database. Conventional (sizing) design parameters such as cross-sectional area of beams or thickness of plates and plane elastic solid components are considered. Compliance, displacement, and stress functionals are considered as performance criteria. The method presented is being extended to implement shape design sensitivity analysis using a domain method and a design component method.

Galactic binary science with the new LISA design

NASA Astrophysics Data System (ADS)

Cornish, Neil; Robson, Travis

2017-05-01

Building on the great success of the LISA Pathfinder mission, the outlines of a new LISA mission design were laid out at the 11th International LISA Symposium in Zurich. The revised design calls for three identical spacecraft forming an equilateral triangle with 2.5 million kilometer sides, and two laser links per side delivering full polarization sensitivity. With the demonstrated Pathfinder performance for the disturbance reduction system, and a well studied design for the laser metrology, it is anticipated that the new mission will have a sensitivity very close to the original LISA design. This implies that the mid-band performance, between 0.5 mHz and 3 mHz, will be limited by unresolved signals from compact binaries in our galaxy. Here we use the new LISA design to compute updated estimates for the galactic confusion noise, the number of resolvable galactic binaries, and the accuracy to which key parameters of these systems can be measured.

Computational Aspects of Sensitivity Calculations in Linear Transient Structural Analysis. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Greene, William H.

1989-01-01

A study has been performed focusing on the calculation of sensitivities of displacements, velocities, accelerations, and stresses in linear, structural, transient response problems. One significant goal was to develop and evaluate sensitivity calculation techniques suitable for large-order finite element analyses. Accordingly, approximation vectors such as vibration mode shapes are used to reduce the dimensionality of the finite element model. Much of the research focused on the accuracy of both response quantities and sensitivities as a function of number of vectors used. Two types of sensitivity calculation techniques were developed and evaluated. The first type of technique is an overall finite difference method where the analysis is repeated for perturbed designs. The second type of technique is termed semianalytical because it involves direct, analytical differentiation of the equations of motion with finite difference approximation of the coefficient matrices. To be computationally practical in large-order problems, the overall finite difference methods must use the approximation vectors from the original design in the analyses of the perturbed models.

Design Optimization Method for Composite Components Based on Moment Reliability-Sensitivity Criteria

NASA Astrophysics Data System (ADS)

Sun, Zhigang; Wang, Changxi; Niu, Xuming; Song, Yingdong

2017-08-01

In this paper, a Reliability-Sensitivity Based Design Optimization (RSBDO) methodology for the design of the ceramic matrix composites (CMCs) components has been proposed. A practical and efficient method for reliability analysis and sensitivity analysis of complex components with arbitrary distribution parameters are investigated by using the perturbation method, the respond surface method, the Edgeworth series and the sensitivity analysis approach. The RSBDO methodology is then established by incorporating sensitivity calculation model into RBDO methodology. Finally, the proposed RSBDO methodology is applied to the design of the CMCs components. By comparing with Monte Carlo simulation, the numerical results demonstrate that the proposed methodology provides an accurate, convergent and computationally efficient method for reliability-analysis based finite element modeling engineering practice.

Estimating the safety benefits of context sensitive solutions.

DOT National Transportation Integrated Search

2011-11-01

Context Sensitive Solutions (CSS), also commonly known by the original name Context Sensitive Design : (CSD), is an alternative approach to the conventional transportation-oriented decision-making and design : processes. The CSS approach can be used ...

The Advanced Gamma-ray Imaging System (AGIS): Camera Electronics Designs

NASA Astrophysics Data System (ADS)

Tajima, H.; Buckley, J.; Byrum, K.; Drake, G.; Falcone, A.; Funk, S.; Holder, J.; Horan, D.; Krawczynski, H.; Ong, R.; Swordy, S.; Wagner, R.; Williams, D.

2008-04-01

AGIS, a next generation of atmospheric Cherenkov telescope arrays, aims to achieve a sensitivity level of a milliCrab for gamma-ray observations in the energy band of 40 GeV to 100 TeV. Such improvement requires cost reduction of individual components with high reliability in order to equip the order of 100 telescopes necessary to achieve the sensitivity goal. We are exploring several design concepts to reduce the cost of camera electronics while improving their performance. These design concepts include systems based on multi-channel waveform sampling ASIC optimized for AGIS, a system based on IIT (image intensifier tube) for large channel (order of 1 million channels) readout as well as a multiplexed FADC system based on the current VERITAS readout design. Here we present trade-off in the studies of these design concepts.

The Advanced Gamma-ray Imaging System (AGIS): Camera Electronics Designs

NASA Astrophysics Data System (ADS)

Tajima, Hiroyasu; Buckley, J.; Byrum, K.; Drake, G.; Falcone, A.; Funk, S.; Holder, J.; Horan, D.; Krawczynski, H.; Ong, R.; Swordy, S.; Wagner, R.; Wakely, S.; Williams, D.; Camera Electronics Working Group; AGIS Collaboration

2008-03-01

AGIS, a next generation of atmospheric Cherenkov telescope arrays, aims to achieve a sensitivity level of a milliCrab for gamma-ray observations in in the energy band of 40 GeV to 100 TeV. Such improvement requires cost reduction of individual components with high reliability in order to equip the order of 100 telescopes necessary to achieve the sensitivity goal. We are exploring several design concepts to reduce the cost of camera electronics while improving their performance. These design concepts include systems based on multi-channel waveform sampling ASIC optimized for AGIS, a system based on IIT (image intensifier tube) for large channel (order of 1 million channels) readout as well as a multiplexed FADC system based on the current VERITAS readout design. Here we present trade-off studies of these design concepts.

Multiobjective robust design of the double wishbone suspension system based on particle swarm optimization.

PubMed

Cheng, Xianfu; 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.

Designing scalable product families by the radial basis function-high-dimensional model representation metamodelling technique

NASA Astrophysics Data System (ADS)

Pirmoradi, Zhila; Haji Hajikolaei, Kambiz; Wang, G. Gary

2015-10-01

Product family design is cost-efficient for achieving the best trade-off between commonalization and diversification. However, for computationally intensive design functions which are viewed as black boxes, the family design would be challenging. A two-stage platform configuration method with generalized commonality is proposed for a scale-based family with unknown platform configuration. Unconventional sensitivity analysis and information on variation in the individual variants' optimal design are used for platform configuration design. Metamodelling is employed to provide the sensitivity and variable correlation information, leading to significant savings in function calls. A family of universal electric motors is designed for product performance and the efficiency of this method is studied. The impact of the employed parameters is also analysed. Then, the proposed method is modified for obtaining higher commonality. The proposed method is shown to yield design solutions with better objective function values, allowable performance loss and higher commonality than the previously developed methods in the literature.

Epidemiological performance and subsequent costs of different surveillance strategies to control bovine herpesvirus type 1 in dairy farms.

PubMed

Veldhuis, Anouk; Santman-Berends, Inge; Schauer, Birgit; Mars, Jet; Waldeck, Frederik; Staubach, Christoph; van Schaik, Gerdien

2017-04-01

This study aimed at comparing the surveillance program of bovine herpesvirus type 1 (BHV1) as laid down by EU Decision 2004/558/EC and 2007/584/EC ('conventional design') with an alternative design. The alternative design was based on monthly bulk-milk testing, clinical surveillance and a risk-based component that involves testing of animals that are purchased from non-free cattle herds. Scenario-tree analyses were carried out to determine sensitivities of the surveillance system (and its components) and the monthly confidence of freedom on herd-level. Also, the expected costs per surveillance design and components thereof were calculated. Results showed that the conventional (EU) and alternative surveillance designs to obtain a BHV1-free status performed equally well in terms of sensitivity. However, total costs per cattle herd to obtain a free status were highest in the conventional design. In an endemic situation and with a within-herd design prevalence of 10%, the conventional design led to a varying probability of freedom ranging from 99.6% to 100% per month. With the alternative design, in this situation, a constant probability of freedom of >99.9% per month was found. In a disease-free situation, both designs performed equally well (probability of freedom >99.9% per month). The yearly costs per farm for monitoring the disease-free status decreased by approximately 25% in the alternative design. The alternative strategy based on monthly bulk-milk monitoring therefore was deemed most cost-effective. This study showed that the surveillance regime to attain and maintain a BHV1-free status as described by EU-legislation can be improved to reduce the monitoring costs without reduction of the system's sensitivity, given a within-herd design prevalence of 10%. The assessment of various surveillance designs could be highly useful to support decision-making towards a more risk-based approach of animal health surveillance. Copyright © 2017 Elsevier B.V. All rights reserved.

Sensitivity computation of the ell1 minimization problem and its application to dictionary design of ill-posed problems

NASA Astrophysics Data System (ADS)

Horesh, L.; Haber, E.

2009-09-01

The ell1 minimization problem has been studied extensively in the past few years. Recently, there has been a growing interest in its application for inverse problems. Most studies have concentrated in devising ways for sparse representation of a solution using a given prototype dictionary. Very few studies have addressed the more challenging problem of optimal dictionary construction, and even these were primarily devoted to the simplistic sparse coding application. In this paper, sensitivity analysis of the inverse solution with respect to the dictionary is presented. This analysis reveals some of the salient features and intrinsic difficulties which are associated with the dictionary design problem. Equipped with these insights, we propose an optimization strategy that alleviates these hurdles while utilizing the derived sensitivity relations for the design of a locally optimal dictionary. Our optimality criterion is based on local minimization of the Bayesian risk, given a set of training models. We present a mathematical formulation and an algorithmic framework to achieve this goal. The proposed framework offers the design of dictionaries for inverse problems that incorporate non-trivial, non-injective observation operators, where the data and the recovered parameters may reside in different spaces. We test our algorithm and show that it yields improved dictionaries for a diverse set of inverse problems in geophysics and medical imaging.

Conceptual design optimization study

NASA Technical Reports Server (NTRS)

Hollowell, S. J.; Beeman, E. R., II; Hiyama, R. M.

1990-01-01

The feasibility of applying multilevel functional decomposition and optimization techniques to conceptual design of advanced fighter aircraft was investigated. Applying the functional decomposition techniques to the conceptual design phase appears to be feasible. The initial implementation of the modified design process will optimize wing design variables. A hybrid approach, combining functional decomposition techniques for generation of aerodynamic and mass properties linear sensitivity derivatives with existing techniques for sizing mission performance and optimization, is proposed.

Analysis and amelioration about the cross-sensitivity of a high resolution MOEMS accelerometer based on diffraction grating

NASA Astrophysics Data System (ADS)

Lu, Qianbo; Bai, Jian; Wang, Kaiwei; Lou, Shuqi; Jiao, Xufen; Han, Dandan

2016-10-01

Cross-sensitivity is a crucial parameter since it detrimentally affect the performance of an accelerometer, especially for a high resolution accelerometer. In this paper, a suite of analytical and finite-elements-method (FEM) models for characterizing the mechanism and features of the cross-sensitivity of a single-axis MOEMS accelerometer composed of a diffraction grating and a micromachined mechanical sensing chip are presented, which have not been systematically investigated yet. The mechanism and phenomena of the cross-sensitivity of this type MOEMS accelerometer based on diffraction grating differ quite a lot from the traditional ones owing to the identical sensing principle. By analyzing the models, some ameliorations and the modified design are put forward to suppress the cross-sensitivity. The modified design, achieved by double sides etching on a specific double-substrate-layer silicon-on-insulator (SOI) wafer, is validated to have a far smaller cross-sensitivity compared with the design previously reported in the literature. Moreover, this design can suppress the cross-sensitivity dramatically without compromising the acceleration sensitivity and resolution.

Stellarator Coil Design and Plasma Sensitivity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Long-Poe Ku and Allen H. Boozer

2010-11-03

The rich information contained in the plasma response to external magnetic perturbations can be used to help design stellarator coils more effectively. We demonstrate the feasibility by first devel- oping a simple, direct method to study perturbations in stellarators that do not break stellarator symmetry and periodicity. The method applies a small perturbation to the plasma boundary and evaluates the resulting perturbed free-boundary equilibrium to build up a sensitivity matrix for the important physics attributes of the underlying configuration. Using this sensitivity information, design methods for better stellarator coils are then developed. The procedure and a proof-of-principle application are givenmore » that (1) determine the spatial distributions of external normal magnetic field at the location of the unperturbed plasma boundary to which the plasma properties are most sen- sitive, (2) determine the distributions of external normal magnetic field that can be produced most efficiently by distant coils, (3) choose the ratios of the magnitudes of the the efficiently produced magnetic distributions so the sensitive plasma properties can be controlled. Using these methods, sets of modular coils are found for the National Compact Stellarator Experiment (NCSX) that are either smoother or can be located much farther from the plasma boundary than those of the present design.« less

[INVITED] Design of turn around point long period fiber grating sensor with Au-nanoparticle self monolayer

NASA Astrophysics Data System (ADS)

Bandyopadhyay, Sankhyabrata; Basumallick, Nandini; Bysakh, Sandip; Dey, Tanoy Kumar; Biswas, Palas; Bandyopadhyay, Somnath

2018-06-01

In this paper studies on the design and fabrication of a long period fiber grating (LPFG) with a self mono layer of gold nanoparticle (AuNP) has been presented. Refractive index (RI) sensitivity of a dispersed cladding mode (DCM) near turn around point (TAP) of its phase matching curve (PMC) has been investigated with and also without AuNP coated LPFG. The typical role played by the intermediate layer of AuNP on the effective index and thus on the sensitivity of the cladding mode to the surrounding RI has also been explored by carrying out coupled mode analysis of the requisite multilayer waveguide. Deposition of AuNP enhanced the sensitivity by more than a factor of 2. Measured sensitivity was found to be ∼3928 nm/refractive index unit (RIU) in the range of 1.3333-1.3428.

Pollution balance method and the demonstration of its application to minimizing waste in a biochemical process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hilaly, A.K.; Sikdar, S.K.

In this study, the authors introduced several modifications to the WAR (waste reduction) algorithm developed earlier. These modifications were made for systematically handling sensitivity analysis and various tasks of waste minimization. A design hierarchy was formulated to promote appropriate waste reduction tasks at designated levels of the hierarchy. A sensitivity coefficient was used to measure the relative impacts of process variables on the pollution index of a process. The use of the WAR algorithm was demonstrated by a fermentation process for making penicillin.

Development of a mass sensitive quartz crystal microbalance (QCM)-based DNA biosensor using a 50 MHz electronic oscillator circuit.

PubMed

García-Martinez, Gonzalo; Bustabad, Enrique Alonso; Perrot, Hubert; Gabrielli, Claude; Bucur, Bogdan; Lazerges, Mathieu; Rose, Daniel; Rodriguez-Pardo, Loreto; Fariña, Jose; Compère, Chantal; Vives, Antonio Arnau

2011-01-01

This work deals with the design of a high sensitivity DNA sequence detector using a 50 MHz quartz crystal microbalance (QCM) electronic oscillator circuit. The oscillator circuitry is based on Miller topology, which is able to work in damping media. Calibration and experimental study of frequency noise are carried out, finding that the designed sensor has a resolution of 7.1 ng/cm(2) in dynamic conditions (with circulation of liquid). Then the oscillator is proved as DNA biosensor. Results show that the system is able to detect the presence of complementary target DNAs in a solution with high selectivity and sensitivity. DNA target concentrations higher of 50 ng/mL can be detected.

Validation of a Brazilian version of the moral sensitivity questionnaire.

PubMed

Dalla Nora, Carlise R; Zoboli, Elma Lcp; Vieira, Margarida M

2017-01-01

Moral sensitivity has been identified as a foundational component of ethical action. Diminished or absent moral sensitivity can result in deficient care. In this context, assessing moral sensitivity is imperative for designing interventions to facilitate ethical practice and ensure that nurses make appropriate decisions. The main purpose of this study was to validate a scale for examining the moral sensitivity of Brazilian nurses. A pre-existing scale, the Moral Sensitivity Questionnaire, which was developed by Lützén, was used after the deletion of three items. The reliability and validity of the scale were examined using Cronbach's alpha and factor analysis, respectively. Participants and research context: Overall, 316 nurses from Rio Grande do Sul, Brazil, participated in the study. Ethical considerations: This study was approved by the Ethics Committee of Research of the Nursing School of the University of São Paulo. The Moral Sensitivity Questionnaire contained 27 items that were distributed across four dimensions: interpersonal orientation, professional knowledge, moral conflict and moral meaning. The questionnaire accounted for 55.8% of the total variance, with Cronbach's alpha of 0.82. The mean score for moral sensitivity was 4.45 (out of 7). The results of this study were compared with studies from other countries to examine the structure and implications of the moral sensitivity of nurses in Brazil. The Moral Sensitivity Questionnaire is an appropriate tool for examining the moral sensitivity of Brazilian nurses.

Model-Based Engineering Design for Trade Space Exploration throughout the Design Cycle

NASA Technical Reports Server (NTRS)

Lamassoure, Elisabeth S.; Wall, Stephen D.; Easter, Robert W.

2004-01-01

This paper presents ongoing work to standardize model-based system engineering as a complement to point design development in the conceptual design phase of deep space missions. It summarizes two first steps towards practical application of this capability within the framework of concurrent engineering design teams and their customers. The first step is standard generation of system sensitivities models as the output of concurrent engineering design sessions, representing the local trade space around a point design. A review of the chosen model development process, and the results of three case study examples, demonstrate that a simple update to the concurrent engineering design process can easily capture sensitivities to key requirements. It can serve as a valuable tool to analyze design drivers and uncover breakpoints in the design. The second step is development of rough-order- of-magnitude, broad-range-of-validity design models for rapid exploration of the trade space, before selection of a point design. At least one case study demonstrated the feasibility to generate such models in a concurrent engineering session. The experiment indicated that such a capability could yield valid system-level conclusions for a trade space composed of understood elements. Ongoing efforts are assessing the practicality of developing end-to-end system-level design models for use before even convening the first concurrent engineering session, starting with modeling an end-to-end Mars architecture.

In silico designing of power conversion efficient organic lead dyes for solar cells using todays innovative approaches to assure renewable energy for future

NASA Astrophysics Data System (ADS)

Kar, Supratik; Roy, Juganta K.; Leszczynski, Jerzy

2017-06-01

Advances in solar cell technology require designing of new organic dye sensitizers for dye-sensitized solar cells with high power conversion efficiency to circumvent the disadvantages of silicon-based solar cells. In silico studies including quantitative structure-property relationship analysis combined with quantum chemical analysis were employed to understand the primary electron transfer mechanism and photo-physical properties of 273 arylamine organic dyes from 11 diverse chemical families explicit to iodine electrolyte. The direct quantitative structure-property relationship models enable identification of the essential electronic and structural attributes necessary for quantifying the molecular prerequisites of 11 classes of arylamine organic dyes, responsible for high power conversion efficiency of dye-sensitized solar cells. Tetrahydroquinoline, N,N'-dialkylaniline and indoline have been least explored classes under arylamine organic dyes for dye-sensitized solar cells. Therefore, the identified properties from the corresponding quantitative structure-property relationship models of the mentioned classes were employed in designing of "lead dyes". Followed by, a series of electrochemical and photo-physical parameters were computed for designed dyes to check the required variables for electron flow of dye-sensitized solar cells. The combined computational techniques yielded seven promising lead dyes each for all three chemical classes considered. Significant (130, 183, and 46%) increment in predicted %power conversion efficiency was observed comparing with the existing dye with highest experimental %power conversion efficiency value for tetrahydroquinoline, N,N'-dialkylaniline and indoline, respectively maintaining required electrochemical parameters.

Chinese nurses' perceived barriers and facilitators of ethical sensitivity.

PubMed

Huang, Fei Fei; Yang, Qing; Zhang, Jie; Khoshnood, Kaveh; Zhang, Jing Ping

2016-08-01

An overview of ethical sensitivity among Chinese registered nurses is needed to develop and optimize the education programs and interventions to cultivate and improve ethical sensitivity. The study was conducted to explore the barriers to and facilitators of ethical sensitivity among Chinese registered nurses working in hospital settings. A convergent parallel mixed-methods research design was adopted. In the cross-sectional quantitative study, the Chinese Moral Sensitivity Questionnaire-revised version was used to assess the levels of ethical sensitivity among registered nurses, and the scores were correlated with key demographics, training experiences in ethics, and workplace cultural environments (n = 306). In the qualitative study, semi-structured interviews were used to elicit the nurses' perceptions of the barriers and facilitators in nurturing ethical sensitivity (n = 15). The data were collected from February to June 2014. This study was approved by the Institutional Review Boards of Yale University and Central South University. Despite moderately high overall Chinese Moral Sensitivity Questionnaire-revised version scores, the ethical sensitivity among Chinese nurses lags in practice. Barriers to ethical sensitivity include the lack of knowledge related to ethics, lack of working experience as a nurse, the hierarchical organizational climate, and the conformist working attitude. The positive workplace cultural environments and application of ethical knowledge in practice were considered potential facilitators of ethical sensitivity. The findings of this study were compared with studies from other countries to examine the barriers and facilitators of ethical sensitivity in Chinese nurses. This mixed-methods study showed that even though the Chinese nurses have moderately high sensitivity to the ethical issues encountered in hospitals, there is still room for improvement. The barriers to and facilitators of ethical sensitivity identified here offer new and important strategies to support and enhance the nurses' sensitivity to ethical issues. © The Author(s) 2015.

Design sensitivity analysis of nonlinear structural response

NASA Technical Reports Server (NTRS)

Cardoso, J. B.; Arora, J. S.

1987-01-01

A unified theory is described of design sensitivity analysis of linear and nonlinear structures for shape, nonshape and material selection problems. The concepts of reference volume and adjoint structure are used to develop the unified viewpoint. A general formula for design sensitivity analysis is derived. Simple analytical linear and nonlinear examples are used to interpret various terms of the formula and demonstrate its use.

Shape optimization using a NURBS-based interface-enriched generalized FEM

DOE PAGES

Najafi, Ahmad R.; Safdari, Masoud; Tortorelli, Daniel A.; ...

2016-11-26

This study presents a gradient-based shape optimization over a fixed mesh using a non-uniform rational B-splines-based interface-enriched generalized finite element method, applicable to multi-material structures. In the proposed method, non-uniform rational B-splines are used to parameterize the design geometry precisely and compactly by a small number of design variables. An analytical shape sensitivity analysis is developed to compute derivatives of the objective and constraint functions with respect to the design variables. Subtle but important new terms involve the sensitivity of shape functions and their spatial derivatives. As a result, verification and illustrative problems are solved to demonstrate the precision andmore » capability of the method.« less

Miniature triaxial metastable ionization detector for gas chromatographic trace analysis of extraterrestrial volatiles

NASA Technical Reports Server (NTRS)

Woeller, F. H.; Kojiro, D. R.; Carle, G. C.

1984-01-01

The present investigation is concerned with a miniature metastable ionization detector featuring an unconventional electrode configuration, whose performance characteristics parallel those of traditional design. The ionization detector is to be incorporated in a flight gas chromatograph (GC) for use in the Space Shuttle. The design of the detector is discussed, taking into account studies which verified the sensitivity of the detector. The triaxial design of the detector is compared with a flat-plate style. The obtained results show that the principal goal of developing a miniature, highly sensitive ionization detector for flight applications was achieved. Improved fabrication techniques will utilize glass-to-metal seals and brazing procedures.

Mindful Music Listening Instruction Increases Listening Sensitivity and Enjoyment

ERIC Educational Resources Information Center

Anderson, William Todd

2016-01-01

The purpose of this study was to examine the effect of mindful listening instruction on music listening sensitivity and music listening enjoyment. A pretest--posttest control group design was used. Participants, fourth-grade students (N = 42) from an elementary school in a large city in the Northeastern United States, were randomly assigned to two…

Cultural Sensitivity Levels of University Students Receiving Education in Health Disciplines

ERIC Educational Resources Information Center

Meydanlioglu, Ayse; Arikan, Fatma; Gozum, Sebahat

2015-01-01

Medical and nursing students are expected to be more competent in terms of being acquainted with different cultures and approaching culturally, compared to many other disciplines. This descriptive study was designed to evaluate the cultural sensitivity levels of nursing and medical students and the affecting factors. One hundred and eleven nursing…

Cold Pressor Pain Sensitivity in Twins Discordant for Chronic Fatigue Syndrome

PubMed Central

Ullrich, Phil; Afari, Niloofar; Jacobsen, Clemma; Goldberg, Jack; Buchwald, Dedra

2010-01-01

Objective Individuals with chronic fatigue syndrome (CFS) experience many pain symptoms. The present study examined whether pain and fatigue ratings and pain threshold and tolerance levels for cold pain differed between twins with CFS and their cotwins without CFS. Design Cotwin control design to assess cold pain sensitivity, pain, and fatigue in monozygotic twins discordant for CFS. Patients and Setting Fifteen twin pairs discordant for CFS recruited from the volunteer Chronic Fatigue Twin Registry at the University of Washington. Results Although cold pain threshold and tolerance levels were slightly lower in twins with CFS than their cotwins without CFS, these differences failed to reach statistical significance. Subjective ratings of pain and fatigue at multiple time points during the experimental protocol among twins with CFS were significantly higher than ratings of pain (p = 0.003) and fatigue (p < 0.001) by their cotwins without CFS. Conclusions These results, while preliminary, highlight the perceptual and cognitive components to the pain experience in CFS. Future studies should focus on examining the heritability of pain sensitivity and the underlying mechanisms involved in the perception of pain sensitivity in CFS. PMID:17371408

Molecular Tools for Diagnosis of Visceral Leishmaniasis: Systematic Review and Meta-Analysis of Diagnostic Test Accuracy

PubMed Central

de Ruiter, C. M.; van der Veer, C.; Leeflang, M. M. G.; Deborggraeve, S.; Lucas, C.

2014-01-01

Molecular methods have been proposed as highly sensitive tools for the detection of Leishmania parasites in visceral leishmaniasis (VL) patients. Here, we evaluate the diagnostic accuracy of these tools in a meta-analysis of the published literature. The selection criteria were original studies that evaluate the sensitivities and specificities of molecular tests for diagnosis of VL, adequate classification of study participants, and the absolute numbers of true positives and negatives derivable from the data presented. Forty studies met the selection criteria, including PCR, real-time PCR, nucleic acid sequence-based amplification (NASBA), and loop-mediated isothermal amplification (LAMP). The sensitivities of the individual studies ranged from 29 to 100%, and the specificities ranged from 25 to 100%. The pooled sensitivity of PCR in whole blood was 93.1% (95% confidence interval [CI], 90.0 to 95.2), and the specificity was 95.6% (95% CI, 87.0 to 98.6). The specificity was significantly lower in consecutive studies, at 63.3% (95% CI, 53.9 to 71.8), due either to true-positive patients not being identified by parasitological methods or to the number of asymptomatic carriers in areas of endemicity. PCR for patients with HIV-VL coinfection showed high diagnostic accuracy in buffy coat and bone marrow, ranging from 93.1 to 96.9%. Molecular tools are highly sensitive assays for Leishmania detection and may contribute as an additional test in the algorithm, together with a clear clinical case definition. We observed wide variety in reference standards and study designs and now recommend consecutively designed studies. PMID:24829226

Architecture as Design Study.

ERIC Educational Resources Information Center

Kauppinen, Heta

1989-01-01

Explores the use of analogies in architectural design, the importance of Gestalt theory and aesthetic cannons in understanding and being sensitive to architecture. Emphasizes the variation between public and professional appreciation of architecture. Notes that an understanding of architectural process enables students to improve the aesthetic…

Design consideration of a multipinhole collimator with septa for ultra high-resolution silicon drift detector modules

NASA Astrophysics Data System (ADS)

Min, Byung Jun; Choi, Yong; Lee, Nam-Yong; Lee, Kisung; Ahn, Young Bok; Joung, Jinhun

2009-07-01

The aim of this study was to design a multipinhole (MP) collimator with lead vertical septa coupled to a high-resolution detector module containing silicon drift detectors (SDDs) with an intrinsic resolution approaching the sub-millimeter level. Monte Carlo simulations were performed to determine pinhole parameters such as pinhole diameter, focal length, and number of pinholes. Effects of parallax error and collimator penetration were investigated for the new MP collimator design. The MP detector module was evaluated using reconstructed images of resolution and mathematical cardiac torso (MCAT) phantoms. In addition, the reduced angular sampling effect was investigated over 180°. The images were reconstructed using dedicated maximum likelihood expectation maximization (MLEM) algorithm. An MP collimator with 81-pinhole was designed with a 2-mm-diameter pinhole and a focal length of 40 mm . Planar sensitivity and resolution obtained using the devised MP collimator were 3.9 cps/μCi and 6 mm full-width at half-maximum (FWHM) at a 10 cm distance. The parallax error and penetration ratio were significantly improved using the proposed MP collimation design. The simulation results demonstrated that the proposed MP detector provided enlarged imaging field of view (FOV) and improved the angular sampling effect in resolution and MCAT phantom studies. Moreover, the novel design enables tomography images by simultaneously obtaining eight projections with eight-detector modules located along the 180° orbit surrounding a patient, which allows designing of a stationary cardiac SPECT. In conclusion, the MP collimator with lead vertical septa was designed to have comparable system resolution and sensitivity to those of the low-energy high-resolution (LEHR) collimator per detector. The system sensitivity with an eight-detector configuration would be four times higher than that with a standard dual-detector cardiac SPECT.

A new x-ray interface and surface scattering environmental cell design for in situ studies of radioactive and atmosphere-sensitive samples.

PubMed

Schmidt, M; Eng, P J; Stubbs, J E; Fenter, P; Soderholm, L

2011-07-01

We present a novel design of a purpose-built, portable sample cell for in situ x-ray scattering experiments of radioactive or atmosphere sensitive samples. The cell has a modular design that includes two independent layers of containment that are used simultaneously to isolate the sensitive samples. Both layers of containment can be flushed with an inert gas, thus serving a double purpose as containment of radiological material (either as a solid sample or as a liquid phase) and in separating reactive samples from the ambient atmosphere. A remote controlled solution flow system is integrated into the containment system that allows sorption experiments to be performed on the diffractometer. The cell's design is discussed in detail and we demonstrate the cell's performance by presenting first results of crystal truncation rod measurements. The results were obtained from muscovite mica single crystals reacted with 1 mM solutions of Th(IV) with 0.1 M NaCl background electrolyte. Data were obtained in specular as well as off-specular geometry.

Surrogate-based Analysis and Optimization

NASA Technical Reports Server (NTRS)

Queipo, Nestor V.; Haftka, Raphael T.; Shyy, Wei; Goel, Tushar; Vaidyanathan, Raj; Tucker, P. Kevin

2005-01-01

A major challenge to the successful full-scale development of modem aerospace systems is to address competing objectives such as improved performance, reduced costs, and enhanced safety. Accurate, high-fidelity models are typically time consuming and computationally expensive. Furthermore, informed decisions should be made with an understanding of the impact (global sensitivity) of the design variables on the different objectives. In this context, the so-called surrogate-based approach for analysis and optimization can play a very valuable role. The surrogates are constructed using data drawn from high-fidelity models, and provide fast approximations of the objectives and constraints at new design points, thereby making sensitivity and optimization studies feasible. This paper provides a comprehensive discussion of the fundamental issues that arise in surrogate-based analysis and optimization (SBAO), highlighting concepts, methods, techniques, as well as practical implications. The issues addressed include the selection of the loss function and regularization criteria for constructing the surrogates, design of experiments, surrogate selection and construction, sensitivity analysis, convergence, and optimization. The multi-objective optimal design of a liquid rocket injector is presented to highlight the state of the art and to help guide future efforts.

Application of Taguchi methods to dual mixture ratio propulsion system optimization for SSTO vehicles

NASA Technical Reports Server (NTRS)

Stanley, Douglas O.; Unal, Resit; Joyner, C. R.

1992-01-01

The application of advanced technologies to future launch vehicle designs would allow the introduction of a rocket-powered, single-stage-to-orbit (SSTO) launch system early in the next century. For a selected SSTO concept, a dual mixture ratio, staged combustion cycle engine that employs a number of innovative technologies was selected as the baseline propulsion system. A series of parametric trade studies are presented to optimize both a dual mixture ratio engine and a single mixture ratio engine of similar design and technology level. The effect of varying lift-off thrust-to-weight ratio, engine mode transition Mach number, mixture ratios, area ratios, and chamber pressure values on overall vehicle weight is examined. The sensitivity of the advanced SSTO vehicle to variations in each of these parameters is presented, taking into account the interaction of each of the parameters with each other. This parametric optimization and sensitivity study employs a Taguchi design method. The Taguchi method is an efficient approach for determining near-optimum design parameters using orthogonal matrices from design of experiments (DOE) theory. Using orthogonal matrices significantly reduces the number of experimental configurations to be studied. The effectiveness and limitations of the Taguchi method for propulsion/vehicle optimization studies as compared to traditional single-variable parametric trade studies is also discussed.

An optimized design to reduce eddy current sensitivity in velocity-selective arterial spin labeling using symmetric BIR-8 pulses.

PubMed

Guo, Jia; Meakin, James A; Jezzard, Peter; Wong, Eric C

2015-03-01

Velocity-selective arterial spin labeling (VSASL) tags arterial blood on a velocity-selective (VS) basis and eliminates the tagging/imaging gap and associated transit delay sensitivity observed in other ASL tagging methods. However, the flow-weighting gradient pulses in VS tag preparation can generate eddy currents (ECs), which may erroneously tag the static tissue and create artificial perfusion signal, compromising the accuracy of perfusion quantification. A novel VS preparation design is presented using an eight-segment B1 insensitive rotation with symmetric radio frequency and gradient layouts (sym-BIR-8), combined with delays after gradient pulses to optimally reduce ECs of a wide range of time constants while maintaining B0 and B1 insensitivity. Bloch simulation, phantom, and in vivo experiments were carried out to determine robustness of the new and existing pulse designs to ECs, B0 , and B1 inhomogeneity. VSASL with reduced EC sensitivity across a wide range of EC time constants was achieved with the proposed sym-BIR-8 design, and the accuracy of cerebral blood flow measurement was improved. The sym-BIR-8 design performed the most robustly among the existing VS tagging designs, and should benefit studies using VS preparation with improved accuracy and reliability. © 2014 Wiley Periodicals, Inc.

Pre-study feasibility and identifying sensitivity analyses for protocol pre-specification in comparative effectiveness research.

PubMed

Girman, Cynthia J; Faries, Douglas; Ryan, Patrick; Rotelli, Matt; Belger, Mark; Binkowitz, Bruce; O'Neill, Robert

2014-05-01

The use of healthcare databases for comparative effectiveness research (CER) is increasing exponentially despite its challenges. Researchers must understand their data source and whether outcomes, exposures and confounding factors are captured sufficiently to address the research question. They must also assess whether bias and confounding can be adequately minimized. Many study design characteristics may impact on the results; however, minimal if any sensitivity analyses are typically conducted, and those performed are post hoc. We propose pre-study steps for CER feasibility assessment and to identify sensitivity analyses that might be most important to pre-specify to help ensure that CER produces valid interpretable results.

The Advanced Gamma-ray Imaging System (AGIS): Simulation Studies

NASA Astrophysics Data System (ADS)

Fegan, Stephen; Buckley, J. H.; Bugaev, S.; Funk, S.; Konopelko, A.; Maier, G.; Vassiliev, V. V.; Simulation Studies Working Group; AGIS Collaboration

2008-03-01

The Advanced Gamma-ray Imaging System (AGIS) is a concept for the next generation instrument in ground-based very high energy gamma-ray astronomy. It has the goal of achieving significant improvement in sensitivity over current experiments. We present the results of simulation studies of various possible designs for AGIS. The primary characteristics of the array performance, collecting area, angular resolution, background rejection, and sensitivity are discussed.

Classroom-Based Phonological Sensitivity Intervention (PSI) Using a Narrative Platform: An Experimental Study of First Graders at Risk for a Reading Disability

ERIC Educational Resources Information Center

Ritter, Michaela J.; Saxon, Terrill F.

2011-01-01

The purpose of this study was to assess the effectiveness of classroom-based phonological sensitivity intervention (PSI) using a narrative platform for children in first grade who are at risk for a reading disability. Participants consisted of 59 first graders identified as at risk for later reading impairments. At-risk designation was dictated by…

Sensitivity enhancement in optical micro-tube resonator sensors via mode coupling

NASA Astrophysics Data System (ADS)

Ling, Tao; Guo, L. Jay

2013-07-01

A liquid filled, silica micro-tube with a low refractive index material inner-coating has been proposed and theoretically studied as a coupled micro-resonator sensor to greatly enhance biochemical sensor sensitivity. Its unique coupling phenomenon has been analyzed and utilized to boost the device's refractive index sensitivity to 967 nm/Refractive Index Unit (RIU). Through optimization of the coupling strength between the two micro-resonators, further improvement in refractive index sensitivity up to 1100 nm/RIU has been predicted. This mode coupling strategy allows us to design robust, thick-walled micro-tube sensors with ultra-high sensitivity which is useful in practical biochemical sensing applications.

Parametric study of a canard-configured transport using conceptual design optimization

NASA Technical Reports Server (NTRS)

Arbuckle, P. D.; Sliwa, S. M.

1985-01-01

Constrained-parameter optimization is used to perform optimal conceptual design of both canard and conventional configurations of a medium-range transport. A number of design constants and design constraints are systematically varied to compare the sensitivities of canard and conventional configurations to a variety of technology assumptions. Main-landing-gear location and canard surface high-lift performance are identified as critical design parameters for a statically stable, subsonic, canard-configured transport.

Crowdsourcing as a screening tool to detect clinical features of glaucomatous optic neuropathy from digital photography.

PubMed

Mitry, Danny; Peto, Tunde; Hayat, Shabina; Blows, Peter; Morgan, James; Khaw, Kay-Tee; Foster, Paul J

2015-01-01

Crowdsourcing is the process of simplifying and outsourcing numerous tasks to many untrained individuals. Our aim was to assess the performance and repeatability of crowdsourcing in the classification of normal and glaucomatous discs from optic disc images. Optic disc images (N = 127) with pre-determined disease status were selected by consensus agreement from grading experts from a large cohort study. After reading brief illustrative instructions, we requested that knowledge workers (KWs) from a crowdsourcing platform (Amazon MTurk) classified each image as normal or abnormal. Each image was classified 20 times by different KWs. Two study designs were examined to assess the effect of varying KW experience and both study designs were conducted twice for consistency. Performance was assessed by comparing the sensitivity, specificity and area under the receiver operating characteristic curve (AUC). Overall, 2,540 classifications were received in under 24 hours at minimal cost. The sensitivity ranged between 83-88% across both trials and study designs, however the specificity was poor, ranging between 35-43%. In trial 1, the highest AUC (95%CI) was 0.64(0.62-0.66) and in trial 2 it was 0.63(0.61-0.65). There were no significant differences between study design or trials conducted. Crowdsourcing represents a cost-effective method of image analysis which demonstrates good repeatability and a high sensitivity. Optimisation of variables such as reward schemes, mode of image presentation, expanded response options and incorporation of training modules should be examined to determine their effect on the accuracy and reliability of this technique in retinal image analysis.

Combined loading criterial influence on structural performance

NASA Technical Reports Server (NTRS)

Kuchta, B. J.; Sealey, D. M.; Howell, L. J.

1972-01-01

An investigation was conducted to determine the influence of combined loading criteria on the space shuttle structural performance. The study consisted of four primary phases: Phase (1) The determination of the sensitivity of structural weight to various loading parameters associated with the space shuttle. Phase (2) The determination of the sensitivity of structural weight to various levels of loading parameter variability and probability. Phase (3) The determination of shuttle mission loading parameters variability and probability as a function of design evolution and the identification of those loading parameters where inadequate data exists. Phase (4) The determination of rational methods of combining both deterministic time varying and probabilistic loading parameters to provide realistic design criteria. The study results are presented.

Bedside diagnosis of dysphagia: a systematic review.

PubMed

O'Horo, John C; Rogus-Pulia, Nicole; Garcia-Arguello, Lisbeth; Robbins, JoAnne; Safdar, Nasia

2015-04-01

Dysphagia is associated with aspiration, pneumonia, and malnutrition, but remains challenging to identify at the bedside. A variety of exam protocols and maneuvers are commonly used, but the efficacy of these maneuvers is highly variable. We conducted a comprehensive search of 7 databases, including MEDLINE, Embase, and Scopus, from each database's earliest inception through June 9, 2014. Studies reporting diagnostic performance of a bedside examination maneuver compared to a reference gold standard (videofluoroscopic swallow study or flexible endoscopic evaluation of swallowing with sensory testing) were included for analysis. From each study, data were abstracted based on the type of diagnostic method and reference standard study population and inclusion/exclusion characteristics, design, and prediction of aspiration. The search strategy identified 38 articles meeting inclusion criteria. Overall, most bedside examinations lacked sufficient sensitivity to be used for screening purposes across all patient populations examined. Individual studies found dysphonia assessments, abnormal pharyngeal sensation assessments, dual axis accelerometry, and 1 description of water swallow testing to be sensitive tools, but none were reported as consistently sensitive. A preponderance of identified studies was in poststroke adults, limiting the generalizability of results. No bedside screening protocol has been shown to provide adequate predictive value for presence of aspiration. Several individual exam maneuvers demonstrated reasonable sensitivity, but reproducibility and consistency of these protocols was not established. More research is needed to design an optimal protocol for dysphagia detection. © 2015 Society of Hospital Medicine.

Proof-of-Concept Study for Uncertainty Quantification and Sensitivity Analysis using the BRL Shaped-Charge Example

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hughes, Justin Matthew

These are the slides for a graduate presentation at Mississippi State University. It covers the following: the BRL Shaped-Charge Geometry in PAGOSA, mesh refinement study, surrogate modeling using a radial basis function network (RBFN), ruling out parameters using sensitivity analysis (equation of state study), uncertainty quantification (UQ) methodology, and sensitivity analysis (SA) methodology. In summary, a mesh convergence study was used to ensure that solutions were numerically stable by comparing PDV data between simulations. A Design of Experiments (DOE) method was used to reduce the simulation space to study the effects of the Jones-Wilkins-Lee (JWL) Parameters for the Composition Bmore » main charge. Uncertainty was quantified by computing the 95% data range about the median of simulation output using a brute force Monte Carlo (MC) random sampling method. Parameter sensitivities were quantified using the Fourier Amplitude Sensitivity Test (FAST) spectral analysis method where it was determined that detonation velocity, initial density, C1, and B1 controlled jet tip velocity.« less

Grid sensitivity capability for large scale structures

NASA Technical Reports Server (NTRS)

Nagendra, Gopal K.; Wallerstein, David V.

1989-01-01

The considerations and the resultant approach used to implement design sensitivity capability for grids into a large scale, general purpose finite element system (MSC/NASTRAN) are presented. The design variables are grid perturbations with a rather general linking capability. Moreover, shape and sizing variables may be linked together. The design is general enough to facilitate geometric modeling techniques for generating design variable linking schemes in an easy and straightforward manner. Test cases have been run and validated by comparison with the overall finite difference method. The linking of a design sensitivity capability for shape variables in MSC/NASTRAN with an optimizer would give designers a powerful, automated tool to carry out practical optimization design of real life, complicated structures.

Developing Tools to Counteract and Prevent Suicide Bomber Incidents: A Case Study in Value Sensitive Design.

PubMed

Royakkers, Lambèr; Steen, Marc

2017-08-01

Developers and designers make all sorts of moral decisions throughout an innovation project. In this article, we describe how teams of developers and designers engaged with ethics in the early phases of innovation based on case studies in the SUBCOP project (SUBCOP stands for 'SUicide Bomber COunteraction and Prevention'). For that purpose, Value Sensitive Design (VSD) will be used as a reference. Specifically, we focus on the following two research questions: How can researchers/developers learn about users' perspectives and values during the innovation process? and How can researchers/developers take into account these values, and related design criteria, in their decision-making during the innovation process? Based on a case study of several innovation processes in this project, we conclude the researchers/developers involved are able to do something similar to VSD (without them knowing about VSD or calling it 'VSD'), supported by relatively simple exercises in the project, e.g., meetings with potential end-users and discussions with members of the Ethical Advisory Board of the project. Furthermore, we also found-possibly somewhat counterintuitively-that a commercial, with its focus on understanding and satisfying customers' needs, can promote VSD.

Search strategies to identify information on adverse effects: a systematic review

PubMed Central

Golder, Su; Loke, Yoon

2009-01-01

Objectives: The review evaluated studies of electronic database search strategies designed to retrieve adverse effects data for systematic reviews. Methods: Studies of adverse effects were located in ten databases as well as by checking references, hand-searching, searching citations, and contacting experts. Two reviewers screened the retrieved records for potentially relevant papers. Results: Five thousand three hundred thirteen citations were retrieved, yielding 19 studies designed to develop or evaluate adverse effect filters, of which 3 met the inclusion criteria. All 3 studies identified highly sensitive search strategies capable of retrieving over 95% of relevant records. However, 1 study did not evaluate precision, while the level of precision in the other 2 studies ranged from 0.8% to 2.8%. Methodological issues in these papers included the relatively small number of records, absence of a validation set of records for testing, and limited evaluation of precision. Conclusions: The results indicate the difficulty of achieving highly sensitive searches for information on adverse effects with a reasonable level of precision. Researchers who intend to locate studies on adverse effects should allow for the amount of resources and time required to conduct a highly sensitive search. PMID:19404498

Definition study for photovoltaic residential prototype system

NASA Technical Reports Server (NTRS)

Imamura, M. S.; Hulstrom, R. L.; Cookson, C.; Waldman, B. H.; Lane, R. A.

1976-01-01

A parametric sensitivity study and definition of the conceptual design is presented. A computer program containing the solar irradiance, solar array, and energy balance models was developed to determine the sensitivities of solar insolation and the corresponding solar array output at five sites selected for this study as well as the performance of several solar array/battery systems. A baseline electrical configuration was chosen, and three design options were recommended. The study indicates that the most sensitive parameters are the solar insolation and the inverter efficiency. The baseline PST selected is comprised of a 133 sg m solar array, 250 ampere hour battery, one to three inverters, and a full shunt regulator to limit the upper solar array voltage. A minicomputer controlled system is recommended to provide the overall control, display, and data acquisition requirements. Architectural renderings of two photovoltaic residential concepts, one above ground and the other underground, are presented. The institutional problems were defined in the areas of legal liabilities during and after installation of the PST, labor practices, building restrictions and architectural guides, and land use.

[Sensitivity to change].

PubMed

Igl, W; Zwingmann, C; Faller, H

2005-04-01

In rehabilitation research patient questionnaires are widely used for evaluative purposes, i. e. to measure improvements or deteriorations over time. This is only possible if the questionnaires applied appropriately reflect "true" change over time, i. e. they have to be sensitive to change. The aim of this paper is to point out the importance of the "sensitivity to change" concept for evaluative assessment tools and evaluative studies, respectively, considering quality of life research as an example. Various qualitative aspects, e. g. scaling of response options of assessment tools, are covered as well as quantitative methods, i. e. study designs and indices. Furthermore, recommendations for interpretation are given.

Computational aspects of sensitivity calculations in linear transient structural analysis. Ph.D. Thesis - Virginia Polytechnic Inst. and State Univ.

NASA Technical Reports Server (NTRS)

Greene, William H.

1990-01-01

A study was performed focusing on the calculation of sensitivities of displacements, velocities, accelerations, and stresses in linear, structural, transient response problems. One significant goal of the study was to develop and evaluate sensitivity calculation techniques suitable for large-order finite element analyses. Accordingly, approximation vectors such as vibration mode shapes are used to reduce the dimensionality of the finite element model. Much of the research focused on the accuracy of both response quantities and sensitivities as a function of number of vectors used. Two types of sensitivity calculation techniques were developed and evaluated. The first type of technique is an overall finite difference method where the analysis is repeated for perturbed designs. The second type of technique is termed semi-analytical because it involves direct, analytical differentiation of the equations of motion with finite difference approximation of the coefficient matrices. To be computationally practical in large-order problems, the overall finite difference methods must use the approximation vectors from the original design in the analyses of the perturbed models. In several cases this fixed mode approach resulted in very poor approximations of the stress sensitivities. Almost all of the original modes were required for an accurate sensitivity and for small numbers of modes, the accuracy was extremely poor. To overcome this poor accuracy, two semi-analytical techniques were developed. The first technique accounts for the change in eigenvectors through approximate eigenvector derivatives. The second technique applies the mode acceleration method of transient analysis to the sensitivity calculations. Both result in accurate values of the stress sensitivities with a small number of modes and much lower computational costs than if the vibration modes were recalculated and then used in an overall finite difference method.

Investigation of Navier-Stokes Code Verification and Design Optimization

NASA Technical Reports Server (NTRS)

Vaidyanathan, Rajkumar

2004-01-01

With rapid progress made in employing computational techniques for various complex Navier-Stokes fluid flow problems, design optimization problems traditionally based on empirical formulations and experiments are now being addressed with the aid of computational fluid dynamics (CFD). To be able to carry out an effective CFD-based optimization study, it is essential that the uncertainty and appropriate confidence limits of the CFD solutions be quantified over the chosen design space. The present dissertation investigates the issues related to code verification, surrogate model-based optimization and sensitivity evaluation. For Navier-Stokes (NS) CFD code verification a least square extrapolation (LSE) method is assessed. This method projects numerically computed NS solutions from multiple, coarser base grids onto a freer grid and improves solution accuracy by minimizing the residual of the discretized NS equations over the projected grid. In this dissertation, the finite volume (FV) formulation is focused on. The interplay between the xi concepts and the outcome of LSE, and the effects of solution gradients and singularities, nonlinear physics, and coupling of flow variables on the effectiveness of LSE are investigated. A CFD-based design optimization of a single element liquid rocket injector is conducted with surrogate models developed using response surface methodology (RSM) based on CFD solutions. The computational model consists of the NS equations, finite rate chemistry, and the k-6 turbulence closure. With the aid of these surrogate models, sensitivity and trade-off analyses are carried out for the injector design whose geometry (hydrogen flow angle, hydrogen and oxygen flow areas and oxygen post tip thickness) is optimized to attain desirable goals in performance (combustion length) and life/survivability (the maximum temperatures on the oxidizer post tip and injector face and a combustion chamber wall temperature). A preliminary multi-objective optimization study is carried out using a geometric mean approach. Following this, sensitivity analyses with the aid of variance-based non-parametric approach and partial correlation coefficients are conducted using data available from surrogate models of the objectives and the multi-objective optima to identify the contribution of the design variables to the objective variability and to analyze the variability of the design variables and the objectives. In summary the present dissertation offers insight into an improved coarse to fine grid extrapolation technique for Navier-Stokes computations and also suggests tools for a designer to conduct design optimization study and related sensitivity analyses for a given design problem.

Molecular engineering of cyanine dyes to design a panchromatic response in Co-sensitized dye-sensitized solar cells

DOE PAGES

Pepe, Giulio; Cole, Jacqueline M.; Waddell, Paul G.; ...

2016-04-05

Cyanines are optically tunable dyes with high molar extinction coefficients, suitable for applications in co-sensitized dye-sensitized solar cells (DSCs); yet, barely thus applied. This might be due to the lack of a rational molecular design strategy that efficiently exploits cyanine properties. This study computationally re-designs these dyes, to broaden their optical absorption spectrum and create dye···TiO 2 binding and co-sensitization functionality. This is achieved via a stepwise molecular engineering approach. Firstly, the structural and optical properties of four parent dyes are experimentally and computationally investigated: 3,3’-diethyloxacarbocyanine iodide, 3,3’-diethylthiacarbocyanine iodide, 3,3’-diethylthiadicarbocyanine iodide and 3,3’-diethylthiatricarbocyanine iodide. Secondly, the molecules are theoretically modifiedmore » and their energetics are analyzed and compared to the parent dyes. A dye···TiO 2 anchoring group (carboxylic or cyanoacrylic acid), absent from the parent dyes, is chemically substituted at different molecular positions to investigate changes in optical absorption. We find that cyanoacrylic acid substitution at the para-quinoidal position affects the absorption wavelength of all parent dyes, with an optimal bathochromic shift of ca. 40 nm. The theoretical lengthening of the polymethine chain is also shown to effect dye absorption. Two molecularly engineered dyes are proposed as promising co-sensitizers. Finally, corresponding dye···TiO 2 adsorption energy calculations corroborate their applicability, demonstrating the potential of cyanine dyes in DSC research.« less

Enhancing Sensitivity in Adolescent Mothers: Does a Standardised, Popular Parenting Intervention Work with Teens?

ERIC Educational Resources Information Center

Bohr, Yvonne; BinNoon, Noam

2014-01-01

This community pilot study was designed to evaluate a small group intervention, Right From The Start (RFTS), in terms of the benefits it provides to adolescent mothers specifically. The effectiveness of the programme was examined in the areas of maternal sensitivity, parenting confidence, parenting stress, and postnatal depression. RFTS has been…

Working Politically amongst Professional Knowledge Landscapes to Implement Gender-Sensitive Physical Education Reform

ERIC Educational Resources Information Center

McCaughtry, Nate

2006-01-01

Background: As the conversation regarding gender and physical education has evolved, a great many suggestions have been offered that reflect ways of designing more gender sensitive environments. The problem now turns the transformation of theoretical suggestions into real change in the practices of schools. Purpose: The purpose of this study was…

Factors Influencing Sensitivity to Lexical Tone in an Artificial Language: Implications for Second Language Learning

ERIC Educational Resources Information Center

Caldwell-Harris, Catherine L.; Lancaster, Alia; Ladd, D. Robert; Dediu, Dan; Christiansen, Morten H.

2015-01-01

This study examined whether musical training, ethnicity, and experience with a natural tone language influenced sensitivity to tone while listening to an artificial tone language. The language was designed with three tones, modeled after level-tone African languages. Participants listened to a 15-min random concatenation of six 3-syllable words.…

A Test of the Homogeneous versus Heterogeneous Categories of the Repression-Sensitization Dimension

ERIC Educational Resources Information Center

Millimet, C. Raymond; Cohen, Howard J.

1973-01-01

A study was designed to examine further the psychometric relationships between the Marlowe-Crown Social Desirability Scale (MC-SDS) and a Repression-Sensitization (R-S) scale in order to affirm or deny the meaningfulness of pairing these two personality measures. The relationships between these measures was considered to be of sufficiently high…

Design optimization and fabrication of a novel structural piezoresistive pressure sensor for micro-pressure measurement

NASA Astrophysics Data System (ADS)

Li, Chuang; Cordovilla, Francisco; Ocaña, José L.

2018-01-01

This paper presents a novel structural piezoresistive pressure sensor with a four-beams-bossed-membrane (FBBM) structure that consisted of four short beams and a central mass to measure micro-pressure. The proposed structure can alleviate the contradiction between sensitivity and linearity to realize the micro measurement with high accuracy. In this study, the design, fabrication and test of the sensor are involved. By utilizing the finite element analysis (FEA) to analyze the stress distribution of sensitive elements and subsequently deducing the relationships between structural dimensions and mechanical performance, the optimization process makes the sensor achieve a higher sensitivity and a lower pressure nonlinearity. Based on the deduced equations, a series of optimized FBBM structure dimensions are ultimately determined. The designed sensor is fabricated on a silicon wafer by using traditional MEMS bulk-micromachining and anodic bonding technology. Experimental results show that the sensor achieves the sensitivity of 4.65 mV/V/kPa and pressure nonlinearity of 0.25% FSS in the operating range of 0-5 kPa at room temperature, indicating that this novel structure sensor can be applied in measuring the absolute micro pressure lower than 5 kPa.

Validation of a patient-centered culturally sensitive health care office staff inventory.

PubMed

Tucker, Carolyn M; Wall, Whitney; Marsiske, Michael; Nghiem, Khanh; Roncoroni, Julia

2015-09-01

Research suggests that patient-perceived culturally sensitive health care encompasses multiple components of the health care delivery system including the cultural sensitivity of front desk office staff. Despite this, research on culturally sensitive health care focuses almost exclusively on provider behaviors, attitudes, and knowledge. This is due in part to the paucity of instruments available to assess the cultural sensitivity of front desk office staff. Thus, the objective of the present study is to determine the psychometric properties of the pilot Tucker-Culturally Sensitive Health Care Office Staff Inventory-Patient Form (T-CSHCOSI-PF), which is an instrument designed to enable patients to evaluate the patient-defined cultural sensitivity of their front desk office staff. A sample of 1648 adult patients was recruited by staff at 67 health care sites across the United States. These patients anonymously completed the T-CSHCOSI-PF, a demographic data questionnaire, and a patient satisfaction questionnaire. Findings Confirmatory factor analyses of the TCSHCOSI-PF revealed that this inventory has two factors with high internal consistency reliability and validity (Cronbach's αs=0.97 and 0.95). It is concluded that the T-CSHCOSI-PF is a psychometrically strong and useful inventory for assessing the cultural sensitivity of front desk office staff. This inventory can be used to support culturally sensitive health care research, evaluate the job performance of front desk office staff, and aid in the development of trainings designed to improve the cultural sensitivity of these office staff.

The art of spacecraft design: A multidisciplinary challenge

NASA Technical Reports Server (NTRS)

Abdi, F.; Ide, H.; Levine, M.; Austel, L.

1989-01-01

Actual design turn-around time has become shorter due to the use of optimization techniques which have been introduced into the design process. It seems that what, how and when to use these optimization techniques may be the key factor for future aircraft engineering operations. Another important aspect of this technique is that complex physical phenomena can be modeled by a simple mathematical equation. The new powerful multilevel methodology reduces time-consuming analysis significantly while maintaining the coupling effects. This simultaneous analysis method stems from the implicit function theorem and system sensitivity derivatives of input variables. Use of the Taylor's series expansion and finite differencing technique for sensitivity derivatives in each discipline makes this approach unique for screening dominant variables from nondominant variables. In this study, the current Computational Fluid Dynamics (CFD) aerodynamic and sensitivity derivative/optimization techniques are applied for a simple cone-type forebody of a high-speed vehicle configuration to understand basic aerodynamic/structure interaction in a hypersonic flight condition.

Charge-transfer-based terbium MOF nanoparticles as fluorescent pH sensor for extreme acidity.

PubMed

Qi, Zewan; Chen, Yang

2017-01-15

Newly emerged metal organic frameworks (MOFs) have aroused the great interest in designing functional materials by means of its flexible structure and component. In this study, we used lanthanide Tb 3+ ions and small molecular ligands to design and assemble a kind of pH-sensitive MOF nanoparticle based on intramolecular-charge-transfer effect. This kind of made-to-order MOF nanoparticle for H + is highly specific and sensitive and could be used to fluorescently indicate pH value of strong acidic solution via preset mechanism through luminescence of Tb 3+ . The long luminescence lifetime of Tb 3+ allows eliminating concomitant non-specific fluorescence by time-revised fluorescence techniques, processing an advantage in sensing H + in biological media with strong autofluorescence. Our method showed a great potential of MOF structures in designing and constructing sensitive sensing materials for specific analytes directly via the assembly of functional ions/ligands. Copyright © 2016 Elsevier B.V. All rights reserved.

High-sensitivity cooled coil system for nuclear magnetic resonance in kHz range

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Tingting; Zhao, Jing, E-mail: zhaojing-8239@jlu.edu.cn; Peter Grünberg Institute

2014-11-15

In several low-field Nuclear Magnetic Resonance (LF-NMR) and surface nuclear magnetic resonance applications, i.e., in the frequency range of kHz, high sensitivity magnetic field detectors are needed. Usually, low-T{sub c} superconducting quantum interference devices (SQUIDs) with a high field sensitivity of about 1 fT/Hz{sup 1/2} are employed as detectors. Considering the flux trapping and operational difficulties associated with low-T{sub c} SQUIDs, we designed and fabricated liquid-nitrogen-cooled Cu coils for NMR detection in the kHz range. A cooled coil system consisting of a 9-cm diameter Cu coil and a low noise preamplifier was systematically investigated and reached a sensitivity of 2more » fT/Hz{sup 1/2} at 77 K, which is 3 times better compared to the sensitivity at 300 K. A Q-switch circuit as an essential element for damping the ringing effects of the pickup coil was developed to acquire free induction decay signals of a water sample with minimum loss of signal. Our studies demonstrate that cooled Cu coils, if designed properly, can provide a comparable sensitivity to low-T{sub c} SQUIDs.« less

Solid state SPS microwave generation and transmission study. Volume 1: Phase 2

NASA Technical Reports Server (NTRS)

Maynard, O. E.

1980-01-01

The solid state sandwich concept for Solar Power Station (SPS) was investigated. The design effort concentrated on the spacetenna, but did include some system analysis for parametric comparison reasons. The study specifically included definition and math modeling of basic solid state microwave devices, an initial conceptual subsystems and system design, sidelobe control and system selection, an assessment of selected system concept and parametric solid state microwave power transmission system data relevant to the SPS concept. Although device efficiency was not a goal, the sensitivities to design of this efficiency were parametrically treated. Sidelobe control consisted of various single step tapers, multistep tapers, and Gaussian tapers. A preliminary assessment of a hybrid concept using tubes and solid state is also included. There is a considerable amount of thermal analysis provided with emphasis on sensitivities to waste heat radiator form factor, emissivity, absorptivity, amplifier efficiency, material and junction temperature.

Application of characteristic time concepts for hydraulic fracture configuration design, control, and optimization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Advani, S.H.; Lee, T.S.; Moon, H.

1992-10-01

The analysis of pertinent energy components or affiliated characteristic times for hydraulic stimulation processes serves as an effective tool for fracture configuration designs optimization, and control. This evaluation, in conjunction with parametric sensitivity studies, provides a rational base for quantifying dominant process mechanisms and the roles of specified reservoir properties relative to controllable hydraulic fracture variables for a wide spectrum of treatment scenarios. Results are detailed for the following multi-task effort: (a) Application of characteristic time concept and parametric sensitivity studies for specialized fracture geometries (rectangular, penny-shaped, elliptical) and three-layered elliptic crack models (in situ stress, elastic moduli, and fracturemore » toughness contrasts). (b) Incorporation of leak-off effects for models investigated in (a). (c) Simulation of generalized hydraulic fracture models and investigation of the role of controllable vaxiables and uncontrollable system properties. (d) Development of guidelines for hydraulic fracture design and optimization.« less

Application of characteristic time concepts for hydraulic fracture configuration design, control, and optimization. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Advani, S.H.; Lee, T.S.; Moon, H.

1992-10-01

The analysis of pertinent energy components or affiliated characteristic times for hydraulic stimulation processes serves as an effective tool for fracture configuration designs optimization, and control. This evaluation, in conjunction with parametric sensitivity studies, provides a rational base for quantifying dominant process mechanisms and the roles of specified reservoir properties relative to controllable hydraulic fracture variables for a wide spectrum of treatment scenarios. Results are detailed for the following multi-task effort: (a) Application of characteristic time concept and parametric sensitivity studies for specialized fracture geometries (rectangular, penny-shaped, elliptical) and three-layered elliptic crack models (in situ stress, elastic moduli, and fracturemore » toughness contrasts). (b) Incorporation of leak-off effects for models investigated in (a). (c) Simulation of generalized hydraulic fracture models and investigation of the role of controllable vaxiables and uncontrollable system properties. (d) Development of guidelines for hydraulic fracture design and optimization.« less

Solid Aerosol Program

DTIC Science & Technology

1993-04-01

not to be construed as an official Department of the Army position unless so designated by other authorizing documents. REPORT DOCUMENTATION PAGE...parameter sensitivity studies, and test procedure design . An experimental system providing reaL data on the parametters relevant to the calculations has been...experimental program was designed to exploit as much of the existing capabilities of the Ventilation Kinetics group as possible while keeping in mind

Negative measurement sensitivity values of planar capacitive imaging probes

NASA Astrophysics Data System (ADS)

Yin, Xiaokang; Chen, Guoming; Li, Wei; Hutchins, David

2014-02-01

The measurement sensitivity distribution of planar capacitive imaging (CI) probes describes how effectively each region in the sensing area is contributing to the measured charge signal on the sensing electrode. It can be used to determine the imaging ability of a CI probe. It is found in previous work that, there are regions in the sensing area where the change of the charge output and the change of targeting physical parameter are of opposite trends. This opposite correlation implies that the measurement sensitivity values in such regions are negative. In this work, the cause of negative sensitivity is discussed. Experiments are also designed and performed so as to verify the existence of negative sensitivity and study the factors that may affect the negative sensitivity distributions.

High sensitivity optical molecular imaging system

NASA Astrophysics Data System (ADS)

An, Yu; Yuan, Gao; Huang, Chao; Jiang, Shixin; Zhang, Peng; Wang, Kun; Tian, Jie

2018-02-01

Optical Molecular Imaging (OMI) has the advantages of high sensitivity, low cost and ease of use. By labeling the regions of interest with fluorescent or bioluminescence probes, OMI can noninvasively obtain the distribution of the probes in vivo, which play the key role in cancer research, pharmacokinetics and other biological studies. In preclinical and clinical application, the image depth, resolution and sensitivity are the key factors for researchers to use OMI. In this paper, we report a high sensitivity optical molecular imaging system developed by our group, which can improve the imaging depth in phantom to nearly 5cm, high resolution at 2cm depth, and high image sensitivity. To validate the performance of the system, special designed phantom experiments and weak light detection experiment were implemented. The results shows that cooperated with high performance electron-multiplying charge coupled device (EMCCD) camera, precision design of light path system and high efficient image techniques, our OMI system can simultaneously collect the light-emitted signals generated by fluorescence molecular imaging, bioluminescence imaging, Cherenkov luminance and other optical imaging modality, and observe the internal distribution of light-emitting agents fast and accurately.

Methods for comparative evaluation of propulsion system designs for supersonic aircraft

NASA Technical Reports Server (NTRS)

Tyson, R. M.; Mairs, R. Y.; Halferty, F. D., Jr.; Moore, B. E.; Chaloff, D.; Knudsen, A. W.

1976-01-01

The propulsion system comparative evaluation study was conducted to define a rapid, approximate method for evaluating the effects of propulsion system changes for an advanced supersonic cruise airplane, and to verify the approximate method by comparing its mission performance results with those from a more detailed analysis. A table look up computer program was developed to determine nacelle drag increments for a range of parametric nacelle shapes and sizes. Aircraft sensitivities to propulsion parameters were defined. Nacelle shapes, installed weights, and installed performance was determined for four study engines selected from the NASA supersonic cruise aircraft research (SCAR) engine studies program. Both rapid evaluation method (using sensitivities) and traditional preliminary design methods were then used to assess the four engines. The method was found to compare well with the more detailed analyses.

SSTO vs TSTO design considerations—an assessment of the overall performance, design considerations, technologies, costs, and sensitivities of SSTO and TSTO designs using modern technologies

NASA Astrophysics Data System (ADS)

Penn, Jay P.

1996-03-01

It is generally believed by those skilled in launch system design that Single-Stage-To-Orbit (SSTO) designs are more technically challenging, more performance sensitive, and yield larger lift-off weights than do Two-Stage-To-Orbit designs (TSTO's) offering similar payload delivery capability. Without additional insight into the other considerations which drive the development, recurring costs, operability, and reliability of a launch fleet, an analyst may easily conclude that the higher performing, less sensitive TSTO designs, thus yield a better solution to achieving low cost payload delivery. This limited insight could justify an argument to eliminate the X-33 SSTO technology/demonstration development effort, and thus proceed directly to less risky TSTO designs. Insight into real world design considerations of launch vehicles makes the choice of SSTO vs TSTO much less clear. The presentation addresses a more comprehensive evaluation of the general class of SSTO and TSTO concepts. These include pure SSTO's, augmented SSTO's, Siamese Twin, and Pure TSTO designs. The assessment considers vehicle performance and scaling relationships which characterize real vehicle designs. The assessment also addresses technology requirements, operations and supportability, cost implications, and sensitivities. Results of the assessment indicate that the trade space between various SSTO and TSTO design approaches is complex and not yet fully understood. The results of the X-33 technology demonstrators, as well as additional parametric analysis is required to better define the relative performance and costs of the various design approaches. The results also indicate that with modern technologies and today's better understanding of vehicle design considerations, the perception that SSTO's are dramatically heavier and more sensitive than TSTO designs is more of a myth, than reality.

Cultural sensitivity and health promotion: assessing breast cancer education pamphlets designed for African American women.

PubMed

Kline, Kimberly N

2007-01-01

This study discusses the implications for cultural sensitivity of the rhetorical choices in breast cancer education materials developed specifically for African American audiences by national organizations. Using the PEN-3 model of cultural sensitivity as an analytic framework for a generative rhetorical criticism, this study revealed that adaptations have been made in some pamphlets to acknowledge African American cultural values related to community, self-reliance, spirituality, and distrust of the Western medical establishment, but many messages could be revised to achieve a more comprehensive, balanced, accurate, and audience-specific discussion of the breast cancer issue. Achieving cultural sensitivity in health promotion materials necessitates attention to nuanced meanings in messages, revision of questionable arguments and evidence, and avoidance of ambiguity.

Attempts to Reach the Oldest and Frailest: Recruitment, Adherence, and Retention of Urban Elderly Persons to a Falls Reduction Exercise Program

ERIC Educational Resources Information Center

Stineman, Margaret G.; Strumpf, Neville; Kurichi, Jibby E.; Charles, Jeremy; Grisso, Jeane Ann; Jayadevappa, Ravishankar

2011-01-01

Purpose of the study: To assess the recruitment, adherence, and retention of urban elderly, predominantly African Americans to a falls reduction exercise program. Design and methods: The randomized controlled trial was designed as an intervention development pilot study. The goal was to develop a culturally sensitive intervention for elderly…

Modeling, design, packing and experimental analysis of liquid-phase shear-horizontal surface acoustic wave sensors

NASA Astrophysics Data System (ADS)

Pollard, Thomas B

Recent advances in microbiology, computational capabilities, and microelectromechanical-system fabrication techniques permit modeling, design, and fabrication of low-cost, miniature, sensitive and selective liquid-phase sensors and lab-on-a-chip systems. Such devices are expected to replace expensive, time-consuming, and bulky laboratory-based testing equipment. Potential applications for devices include: fluid characterization for material science and industry; chemical analysis in medicine and pharmacology; study of biological processes; food analysis; chemical kinetics analysis; and environmental monitoring. When combined with liquid-phase packaging, sensors based on surface-acoustic-wave (SAW) technology are considered strong candidates. For this reason such devices are focused on in this work; emphasis placed on device modeling and packaging for liquid-phase operation. Regarding modeling, topics considered include mode excitation efficiency of transducers; mode sensitivity based on guiding structure materials/geometries; and use of new piezoelectric materials. On packaging, topics considered include package interfacing with SAW devices, and minimization of packaging effects on device performance. In this work novel numerical models are theoretically developed and implemented to study propagation and transduction characteristics of sensor designs using wave/constitutive equations, Green's functions, and boundary/finite element methods. Using developed simulation tools that consider finite-thickness of all device electrodes, transduction efficiency for SAW transducers with neighboring uniform or periodic guiding electrodes is reported for the first time. Results indicate finite electrode thickness strongly affects efficiency. Using dense electrodes, efficiency is shown to approach 92% and 100% for uniform and periodic electrode guiding, respectively; yielding improved sensor detection limits. A numerical sensitivity analysis is presented targeting viscosity using uniform-electrode and shear-horizontal mode configurations on potassium-niobate, langasite, and quartz substrates. Optimum configurations are determined yielding maximum sensitivity. Results show mode propagation-loss and sensitivity to viscosity are correlated by a factor independent of substrate material. The analysis is useful for designing devices meeting sensitivity and signal level requirements. A novel, rapid and precise microfluidic chamber alignment/bonding method was developed for SAW platforms. The package is shown to have little effect on device performance and permits simple macrofluidic interfacing. Lastly, prototypes were designed, fabricated, and tested for viscosity and biosensor applications; results show ability to detect as low as 1% glycerol in water and surface-bound DNA crosslinking.

Temperament, character and anxiety sensitivity in panic disorder: a high-risk study.

PubMed

Perna, Giampaolo; di Pasquale, Danila; Grassi, Massimiliano; Vanni, Giovanna; Bellodi, Laura; Caldirola, Daniela

2012-01-01

Adult patients with panic disorder (PD) show high levels of harm avoidance and anxiety sensitivity. Peculiar temperament profiles and high anxiety sensitivity have been proposed as developmental risk factors for PD in adult age. Since familial-genetic influences play a role both in PD and in anxiety sensitivity and temperament profiles, this study aims to investigate the possible association between family history of PD and peculiar temperament-character profiles or high anxiety sensitivity in offspring of patients with PD. Thirty-four children of patients with PD with/without agoraphobia and 30 children of healthy subjects were compared. Temperament and character dimensions and anxiety sensitivity levels of children were obtained by the Junior Temperament and Character Inventory and the Childhood Anxiety Sensitivity Index. Children of patients with PD and children of healthy subjects differed neither in temperament and character dimensions nor in anxiety sensitivity levels. Our results show that family history of PD is not associated with peculiar temperament and character profiles or high anxiety sensitivity in children, suggesting that these factors may not be early expressions of familial vulnerability to PD. Since the sample is small and the study has a cross-sectional design, longitudinal studies in larger samples are warranted to confirm these findings and to clarify the role of anxiety sensitivity and temperament-character dimensions in the development of PD. Copyright © 2012 S. Karger AG, Basel.

Molecular tools for diagnosis of visceral leishmaniasis: systematic review and meta-analysis of diagnostic test accuracy.

PubMed

de Ruiter, C M; van der Veer, C; Leeflang, M M G; Deborggraeve, S; Lucas, C; Adams, E R

2014-09-01

Molecular methods have been proposed as highly sensitive tools for the detection of Leishmania parasites in visceral leishmaniasis (VL) patients. Here, we evaluate the diagnostic accuracy of these tools in a meta-analysis of the published literature. The selection criteria were original studies that evaluate the sensitivities and specificities of molecular tests for diagnosis of VL, adequate classification of study participants, and the absolute numbers of true positives and negatives derivable from the data presented. Forty studies met the selection criteria, including PCR, real-time PCR, nucleic acid sequence-based amplification (NASBA), and loop-mediated isothermal amplification (LAMP). The sensitivities of the individual studies ranged from 29 to 100%, and the specificities ranged from 25 to 100%. The pooled sensitivity of PCR in whole blood was 93.1% (95% confidence interval [CI], 90.0 to 95.2), and the specificity was 95.6% (95% CI, 87.0 to 98.6). The specificity was significantly lower in consecutive studies, at 63.3% (95% CI, 53.9 to 71.8), due either to true-positive patients not being identified by parasitological methods or to the number of asymptomatic carriers in areas of endemicity. PCR for patients with HIV-VL coinfection showed high diagnostic accuracy in buffy coat and bone marrow, ranging from 93.1 to 96.9%. Molecular tools are highly sensitive assays for Leishmania detection and may contribute as an additional test in the algorithm, together with a clear clinical case definition. We observed wide variety in reference standards and study designs and now recommend consecutively designed studies. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Sensitivity analysis, approximate analysis, and design optimization for internal and external viscous flows

NASA Technical Reports Server (NTRS)

Taylor, Arthur C., III; Hou, Gene W.; Korivi, Vamshi M.

1991-01-01

A gradient-based design optimization strategy for practical aerodynamic design applications is presented, which uses the 2D thin-layer Navier-Stokes equations. The strategy is based on the classic idea of constructing different modules for performing the major tasks such as function evaluation, function approximation and sensitivity analysis, mesh regeneration, and grid sensitivity analysis, all driven and controlled by a general-purpose design optimization program. The accuracy of aerodynamic shape sensitivity derivatives is validated on two viscous test problems: internal flow through a double-throat nozzle and external flow over a NACA 4-digit airfoil. A significant improvement in aerodynamic performance has been achieved in both cases. Particular attention is given to a consistent treatment of the boundary conditions in the calculation of the aerodynamic sensitivity derivatives for the classic problems of external flow over an isolated lifting airfoil on 'C' or 'O' meshes.

Stochastic sensitivity measure for mistuned high-performance turbines

NASA Technical Reports Server (NTRS)

Murthy, Durbha V.; Pierre, Christophe

1992-01-01

A stochastic measure of sensitivity is developed in order to predict the effects of small random blade mistuning on the dynamic aeroelastic response of turbomachinery blade assemblies. This sensitivity measure is based solely on the nominal system design (i.e., on tuned system information), which makes it extremely easy and inexpensive to calculate. The measure has the potential to become a valuable design tool that will enable designers to evaluate mistuning effects at a preliminary design stage and thus assess the need for a full mistuned rotor analysis. The predictive capability of the sensitivity measure is illustrated by examining the effects of mistuning on the aeroelastic modes of the first stage of the oxidizer turbopump in the Space Shuttle Main Engine. Results from a full analysis mistuned systems confirm that the simple stochastic sensitivity measure predicts consistently the drastic changes due to misturning and the localization of aeroelastic vibration to a few blades.

Improving multi-objective reservoir operation optimization with sensitivity-informed dimension reduction

NASA Astrophysics Data System (ADS)

Chu, J.; Zhang, C.; Fu, G.; Li, Y.; Zhou, H.

2015-08-01

This study investigates the effectiveness of a sensitivity-informed method for multi-objective operation of reservoir systems, which uses global sensitivity analysis as a screening tool to reduce computational demands. Sobol's method is used to screen insensitive decision variables and guide the formulation of the optimization problems with a significantly reduced number of decision variables. This sensitivity-informed method dramatically reduces the computational demands required for attaining high-quality approximations of optimal trade-off relationships between conflicting design objectives. The search results obtained from the reduced complexity multi-objective reservoir operation problems are then used to pre-condition the full search of the original optimization problem. In two case studies, the Dahuofang reservoir and the inter-basin multi-reservoir system in Liaoning province, China, sensitivity analysis results show that reservoir performance is strongly controlled by a small proportion of decision variables. Sensitivity-informed dimension reduction and pre-conditioning are evaluated in their ability to improve the efficiency and effectiveness of multi-objective evolutionary optimization. Overall, this study illustrates the efficiency and effectiveness of the sensitivity-informed method and the use of global sensitivity analysis to inform dimension reduction of optimization problems when solving complex multi-objective reservoir operation problems.

Improving multi-objective reservoir operation optimization with sensitivity-informed problem decomposition

NASA Astrophysics Data System (ADS)

Chu, J. G.; Zhang, C.; Fu, G. T.; Li, Y.; Zhou, H. C.

2015-04-01

This study investigates the effectiveness of a sensitivity-informed method for multi-objective operation of reservoir systems, which uses global sensitivity analysis as a screening tool to reduce the computational demands. Sobol's method is used to screen insensitive decision variables and guide the formulation of the optimization problems with a significantly reduced number of decision variables. This sensitivity-informed problem decomposition dramatically reduces the computational demands required for attaining high quality approximations of optimal tradeoff relationships between conflicting design objectives. The search results obtained from the reduced complexity multi-objective reservoir operation problems are then used to pre-condition the full search of the original optimization problem. In two case studies, the Dahuofang reservoir and the inter-basin multi-reservoir system in Liaoning province, China, sensitivity analysis results show that reservoir performance is strongly controlled by a small proportion of decision variables. Sensitivity-informed problem decomposition and pre-conditioning are evaluated in their ability to improve the efficiency and effectiveness of multi-objective evolutionary optimization. Overall, this study illustrates the efficiency and effectiveness of the sensitivity-informed method and the use of global sensitivity analysis to inform problem decomposition when solving the complex multi-objective reservoir operation problems.

Preparation for implementation of the mechanistic-empirical pavement design guide in Michigan : part 2 - evaluation of rehabilitation fixes (part 2).

DOT National Transportation Integrated Search

2013-08-01

The overall goal of Global Sensitivity Analysis (GSA) is to determine sensitivity of pavement performance prediction models to the variation in the design input values. The main difference between GSA and detailed sensitivity analyses is the way the ...

The Advanced Gamma-ray Imageing System (AGIS): Simulation Design Studies

NASA Astrophysics Data System (ADS)

Bugaev, V.; Buckley, J.; Digel, S.; Fegan, S.; Funk, S.; Konopelko, A.; Krawczynski, H.; Lebohec, S.; Maier, G.; Vassiliev, V.

2008-04-01

We present design studies for AGIS, a proposed array of ˜100 imaging atmospheric Cherenkov telescopes for gamma-rays astronomy in the 40GeV to 100 TeV energy regime. We describe optimization studies for the array configuration, pixel size and field of view aimed at achieving the best sensitivity over the entire energy range and best angular resolution for a fixed project total cost.

High-throughput spectrometer designs in a compact form-factor: principles and applications

NASA Astrophysics Data System (ADS)

Norton, S. M.

2013-05-01

Many compact, portable Raman spectrometers have entered the market in the past few years with applications in narcotics and hazardous material identification, as well as verification applications in pharmaceuticals and security screening. Often, the required compact form-factor has forced designers to sacrifice throughput and sensitivity for portability and low-cost. We will show that a volume phase holographic (VPH)-based spectrometer design can achieve superior throughput and thus sensitivity over conventional Czerny-Turner reflective designs. We will look in depth at the factors influencing throughput and sensitivity and illustrate specific VPH-based spectrometer examples that highlight these design principles.

Comparative analytical evaluation of the respiratory TaqMan Array Card with real-time PCR and commercial multi-pathogen assays.

PubMed

Harvey, John J; Chester, Stephanie; Burke, Stephen A; Ansbro, Marisela; Aden, Tricia; Gose, Remedios; Sciulli, Rebecca; Bai, Jing; DesJardin, Lucy; Benfer, Jeffrey L; Hall, Joshua; Smole, Sandra; Doan, Kimberly; Popowich, Michael D; St George, Kirsten; Quinlan, Tammy; Halse, Tanya A; Li, Zhen; Pérez-Osorio, Ailyn C; Glover, William A; Russell, Denny; Reisdorf, Erik; Whyte, Thomas; Whitaker, Brett; Hatcher, Cynthia; Srinivasan, Velusamy; Tatti, Kathleen; Tondella, Maria Lucia; Wang, Xin; Winchell, Jonas M; Mayer, Leonard W; Jernigan, Daniel; Mawle, Alison C

2016-02-01

In this study, a multicenter evaluation of the Life Technologies TaqMan(®) Array Card (TAC) with 21 custom viral and bacterial respiratory assays was performed on the Applied Biosystems ViiA™ 7 Real-Time PCR System. The goal of the study was to demonstrate the analytical performance of this platform when compared to identical individual pathogen specific laboratory developed tests (LDTs) designed at the Centers for Disease Control and Prevention (CDC), equivalent LDTs provided by state public health laboratories, or to three different commercial multi-respiratory panels. CDC and Association of Public Health Laboratories (APHL) LDTs had similar analytical sensitivities for viral pathogens, while several of the bacterial pathogen APHL LDTs demonstrated sensitivities one log higher than the corresponding CDC LDT. When compared to CDC LDTs, TAC assays were generally one to two logs less sensitive depending on the site performing the analysis. Finally, TAC assays were generally more sensitive than their counterparts in three different commercial multi-respiratory panels. TAC technology allows users to spot customized assays and design TAC layout, simplify assay setup, conserve specimen, dramatically reduce contamination potential, and as demonstrated in this study, analyze multiple samples in parallel with good reproducibility between instruments and operators. Copyright © 2015 Elsevier B.V. All rights reserved.

Preliminary design of a mini-Brayton Compressor-Alternator-Turbine (CAT)

NASA Technical Reports Server (NTRS)

1973-01-01

The preliminary design of a mini-Brayton compressor-alternator-turbine system is discussed. The program design goals are listed. The optimum system characteristics over the entire range of power output were determined by performing a wide-range parametric study. The ability to develop the required components to the degree necessary within the limitations of present technology is evaluated. The sensitivity of the system to various individual design parameters was analyzed.

A stereo-compound hybrid microscope for combined intracellular and optical recording of invertebrate neural network activity.

PubMed

Frost, William N; Wang, Jean; Brandon, Christopher J

2007-05-15

Optical recording studies of invertebrate neural networks with voltage-sensitive dyes seldom employ conventional intracellular electrodes. This may in part be due to the traditional reliance on compound microscopes for such work. While such microscopes have high light-gathering power, they do not provide depth of field, making working with sharp electrodes difficult. Here we describe a hybrid microscope design, with switchable compound and stereo objectives, that eases the use of conventional intracellular electrodes in optical recording experiments. We use it, in combination with a voltage-sensitive dye and photodiode array, to identify neurons participating in the swim motor program of the marine mollusk Tritonia. This microscope design should be applicable to optical recording studies in many preparations.

Comparing performance of mothers using simplified mid-upper arm circumference (MUAC) classification devices with an improved MUAC insertion tape in Isiolo County, Kenya.

PubMed

Grant, Angeline; Njiru, James; Okoth, Edgar; Awino, Imelda; Briend, André; Murage, Samuel; Abdirahman, Saida; Myatt, Mark

2018-01-01

A novel approach for improving community case-detection of acute malnutrition involves mothers/caregivers screening their children for acute malnutrition using a mid-upper arm circumference (MUAC) insertion tape. The objective of this study was to test three simple MUAC classification devices to determine whether they improved the sensitivity of mothers/caregivers at detecting acute malnutrition. Prospective, non-randomised, partially-blinded, clinical diagnostic trial describing and comparing the performance of three "Click-MUAC" devices and a MUAC insertion tape. The study took place in twenty-one health facilities providing integrated management of acute malnutrition (IMAM) services in Isiolo County, Kenya. Mothers/caregivers classified their child ( n =1040), aged 6-59 months, using the "Click-MUAC" devices and a MUAC insertion tape. These classifications were compared to a "gold standard" classification (the mean of three measurements taken by a research assistant using the MUAC insertion tape). The sensitivity of mother/caregiver classifications was high for all devices (>93% for severe acute malnutrition (SAM), defined by MUAC < 115 mm, and > 90% for global acute malnutrition (GAM), defined by MUAC < 125 mm). Mother/caregiver sensitivity for SAM and GAM classification was higher using the MUAC insertion tape (100% sensitivity for SAM and 99% sensitivity for GAM) than using "Click-MUAC" devices. Younden's J for SAM classification, and sensitivity for GAM classification, were significantly higher for the MUAC insertion tape (99% and 99% respectively). Specificity was high for all devices (>96%) with no significant difference between the "Click-MUAC" devices and the MUAC insertion tape. The results of this study indicate that, although the "Click-MUAC" devices performed well, the MUAC insertion tape performed best. The results for sensitivity are higher than found in previous studies. The high sensitivity for both SAM and GAM classification by mothers/caregivers with the MUAC insertion tape could be due to the use of an improved MUAC tape design which has a number of new design features. The one-on-one demonstration provided to mothers/caregivers on the use of the devices may also have helped improve sensitivity. The results of this study provide evidence that mothers/caregivers can perform sensitive and specific classifications of their child's nutritional status using MUAC. Clinical trials registration number: NCT02833740.

A trigger-based design for evaluating the safety of in utero antiretroviral exposure in uninfected children of human immunodeficiency virus-infected mothers.

PubMed

Williams, Paige L; Seage, George R; Van Dyke, Russell B; Siberry, George K; Griner, Raymond; Tassiopoulos, Katherine; Yildirim, Cenk; Read, Jennifer S; Huo, Yanling; Hazra, Rohan; Jacobson, Denise L; Mofenson, Lynne M; Rich, Kenneth

2012-05-01

The Pediatric HIV/AIDS Cohort Study's Surveillance Monitoring of ART Toxicities Study is a prospective cohort study conducted at 22 US sites between 2007 and 2011 that was designed to evaluate the safety of in utero antiretroviral drug exposure in children not infected with human immunodeficiency virus who were born to mothers who were infected. This ongoing study uses a "trigger-based" design; that is, initial assessments are conducted on all children, and only those meeting certain thresholds or "triggers" undergo more intensive evaluations to determine whether they have had an adverse event (AE). The authors present the estimated rates of AEs for each domain of interest in the Surveillance Monitoring of ART Toxicities Study. They also evaluated the efficiency of this trigger-based design for estimating AE rates and for testing associations between in utero exposures to antiretroviral drugs and AEs. The authors demonstrate that estimated AE rates from the trigger-based design are unbiased after correction for the sensitivity of the trigger for identifying AEs. Even without correcting for bias based on trigger sensitivity, the trigger approach is generally more efficient for estimating AE rates than is evaluating a random sample of the same size. Minor losses in efficiency when comparing AE rates between persons exposed and unexposed in utero to particular antiretroviral drugs or drug classes were observed under most scenarios.

Respiratory allergen from house dust mite is present in human milk and primes for allergic sensitization in a mouse model of asthma.

PubMed

Macchiaverni, P; Rekima, A; Turfkruyer, M; Mascarell, L; Airouche, S; Moingeon, P; Adel-Patient, K; Condino-Neto, A; Annesi-Maesano, I; Prescott, S L; Tulic, M K; Verhasselt, V

2014-03-01

There is an urgent need to identify environmental risk and protective factors in early life for the prevention of allergy. Our study demonstrates the presence of respiratory allergen from house dust mite, Der p 1, in human breast milk. Der p 1 in milk is immunoreactive, present in similar amounts as dietary egg antigen, and can be found in breast milk from diverse regions of the world. In a mouse model of asthma, oral exposure to Der p through breast milk strongly promotes sensitization rather than protect the progeny as we reported with egg antigen. These data highlight that antigen administration to the neonate through the oral route may contribute to child allergic sensitization and have important implications for the design of studies assessing early oral antigen exposure for allergic disease prevention. The up-to-now unknown worldwide presence of respiratory allergen in maternal milk allows new interpretation and design of environmental control epidemiological studies for allergic disease prevention. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Concurrent Validity and Sensitivity to Change of Direct Behavior Rating Single-Item Scales (DBR-SIS) within an Elementary Sample

ERIC Educational Resources Information Center

Smith, Rhonda L.; Eklund, Katie; Kilgus, Stephen P.

2018-01-01

The purpose of this study was to evaluate the concurrent validity, sensitivity to change, and teacher acceptability of Direct Behavior Rating single-item scales (DBR-SIS), a brief progress monitoring measure designed to assess student behavioral change in response to intervention. Twenty-four elementary teacher-student dyads implemented a daily…

Design of helicopter rotors to noise constraints

NASA Technical Reports Server (NTRS)

Schaeffer, E. G.; Sternfeld, H., Jr.

1978-01-01

Results of the initial phase of a research project to study the design constraints on helicopter noise are presented. These include the calculation of nonimpulsive rotor harmonic and broadband hover noise spectra, over a wide range of rotor design variables and the sensitivity of perceived noise level (PNL) to changes in rotor design parameters. The prediction methodology used correlated well with measured whirl tower data. Application of the predictions to variations in rotor design showed tip speed and thrust as having the most effect on changing PNL.

Development and validation of coaxial cable sensors for damage detection of reinforced concrete structures

NASA Astrophysics Data System (ADS)

Mu, Huimin

Coaxial cables are mainly composed of inner and outer conductors, and a dielectric layer in between. In this study they are proposed as continuous sensors for monitoring of civil infrastructures. Due to small deformation and minor cracks of engineering interest, coaxial cables have never been applied into reinforced concrete (RC) structures until the late 1990s. The state of the art in design of a cable sensor is to replace the polyethylene pipe of a commercial cable with a rubber tube as a dielectric layer to increase the cable's sensitivity up to 10 times. In this dissertation a new design of prototype cable sensor is proposed. The new sensors not only respond to the cable's elongation directly but, more significantly, to the topology change in the outer conductor associated with the cable elongation. The latter effect is first proposed and investigated in this study. An analytical model of the proposed sensor design was developed in this study to establish the relation between the directly measurable quantities with design parameters. Four types of the sensors with various parameters were also numerically simulated to confirm the analytical results. Both analytical and numerical results were validated through experimentation. After having calibrated with the strain applied on them, the sensors were embedded into twelve RC beams to understand how sensitive they are to stressing and cracking in RC beams. The results from the flexural tests indicated that the sensitivity of the newly designed sensors is 50˜100 times higher than that of commercial cables to the longitudinal elongation. The new sensors can be used to successfully detect both the location and width of a crack in RC members.

Optimal two-phase sampling design for comparing accuracies of two binary classification rules.

PubMed

Xu, Huiping; Hui, Siu L; Grannis, Shaun

2014-02-10

In this paper, we consider the design for comparing the performance of two binary classification rules, for example, two record linkage algorithms or two screening tests. Statistical methods are well developed for comparing these accuracy measures when the gold standard is available for every unit in the sample, or in a two-phase study when the gold standard is ascertained only in the second phase in a subsample using a fixed sampling scheme. However, these methods do not attempt to optimize the sampling scheme to minimize the variance of the estimators of interest. In comparing the performance of two classification rules, the parameters of primary interest are the difference in sensitivities, specificities, and positive predictive values. We derived the analytic variance formulas for these parameter estimates and used them to obtain the optimal sampling design. The efficiency of the optimal sampling design is evaluated through an empirical investigation that compares the optimal sampling with simple random sampling and with proportional allocation. Results of the empirical study show that the optimal sampling design is similar for estimating the difference in sensitivities and in specificities, and both achieve a substantial amount of variance reduction with an over-sample of subjects with discordant results and under-sample of subjects with concordant results. A heuristic rule is recommended when there is no prior knowledge of individual sensitivities and specificities, or the prevalence of the true positive findings in the study population. The optimal sampling is applied to a real-world example in record linkage to evaluate the difference in classification accuracy of two matching algorithms. Copyright © 2013 John Wiley & Sons, Ltd.

Design of optimal collimation for dedicated molecular breast imaging systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weinmann, Amanda L.; Hruska, Carrie B.; O'Connor, Michael K.

2009-03-15

Molecular breast imaging (MBI) is a functional imaging technique that uses specialized small field-of-view gamma cameras to detect the preferential uptake of a radiotracer in breast lesions. MBI has potential to be a useful adjunct method to screening mammography for the detection of occult breast cancer. However, a current limitation of MBI is the high radiation dose (a factor of 7-10 times that of screening mammography) associated with current technology. The purpose of this study was to optimize the gamma camera collimation with the aim of improving sensitivity while retaining adequate resolution for the detection of sub-10-mm lesions. Square-hole collimatorsmore » with holes matched to the pixilated cadmium zinc telluride detector elements of the MBI system were designed. Data from MBI patient studies and parameters of existing dual-head MBI systems were used to guide the range of desired collimator resolutions, source-to-collimator distances, pixel sizes, and collimator materials that were examined. General equations describing collimator performance for a conventional gamma camera were used in the design process along with several important adjustments to account for the specialized imaging geometry of the MBI system. Both theoretical calculations and a Monte Carlo model were used to measure the geometric efficiency (or sensitivity) and resolution of each designed collimator. Results showed that through optimal collimation, collimator sensitivity could be improved by factors of 1.5-3.2, while maintaining a collimator resolution of either {<=}5 or {<=}7.5 mm at a distance of 3 cm from the collimator face. These gains in collimator sensitivity permit an inversely proportional drop in the required dose to perform MBI.« less

CORSSTOL: Cylinder Optimization of Rings, Skin, and Stringers with Tolerance sensitivity

NASA Technical Reports Server (NTRS)

Finckenor, J.; Bevill, M.

1995-01-01

Cylinder Optimization of Rings, Skin, and Stringers with Tolerance (CORSSTOL) sensitivity is a design optimization program incorporating a method to examine the effects of user-provided manufacturing tolerances on weight and failure. CORSSTOL gives designers a tool to determine tolerances based on need. This is a decisive way to choose the best design among several manufacturing methods with differing capabilities and costs. CORSSTOL initially optimizes a stringer-stiffened cylinder for weight without tolerances. The skin and stringer geometry are varied, subject to stress and buckling constraints. Then the same analysis and optimization routines are used to minimize the maximum material condition weight subject to the least favorable combination of tolerances. The adjusted optimum dimensions are provided with the weight and constraint sensitivities of each design variable. The designer can immediately identify critical tolerances. The safety of parts made out of tolerance can also be determined. During design and development of weight-critical systems, design/analysis tools that provide product-oriented results are of vital significance. The development of this program and methodology provides designers with an effective cost- and weight-saving design tool. The tolerance sensitivity method can be applied to any system defined by a set of deterministic equations.

LASER BIOLOGY AND MEDICINE: Application of tunable diode lasers for a highly sensitive analysis of gaseous biomarkers in exhaled air

NASA Astrophysics Data System (ADS)

Stepanov, E. V.; Milyaev, Varerii A.

2002-11-01

The application of tunable diode lasers for a highly sensitive analysis of gaseous biomarkers in exhaled air in biomedical diagnostics is discussed. The principle of operation and the design of a laser analyser for studying the composition of exhaled air are described. The results of detection of gaseous biomarkers in exhaled air, including clinical studies, which demonstrate the diagnostic possibilities of the method, are presented.

Bedside Diagnosis of Dysphagia: A Systematic Review

PubMed Central

O’Horo, John C.; Rogus-Pulia, Nicole; Garcia-Arguello, Lisbeth; Robbins, JoAnne; Safdar, Nasia

2015-01-01

Background Dysphagia is associated with aspiration, pneumonia and malnutrition, but remains challenging to identify at the bedside. A variety of exam protocols and maneuvers are commonly used, but the efficacy of these maneuvers is highly variable. Methods We conducted a comprehensive search of seven databases, including MEDLINE, EMBASE and Scopus, from each database’s earliest inception through June 5th, 2013. Studies reporting diagnostic performance of a bedside examination maneuver compared to a reference gold standard (videofluoroscopic swallow study [VFSS] or flexible endoscopic evaluation of swallowing with sensory testing [FEEST]) were included for analysis. From each study, data were abstracted based on the type of diagnostic method and reference standard study population and inclusion/exclusion characteristics, design and prediction of aspiration. Results The search strategy identified 38 articles meeting inclusion criteria. Overall, most bedside examinations lacked sufficient sensitivity to be used for screening purposes across all patient populations examined. Individual studies found dysphonia assessments, abnormal pharyngeal sensation assessments, dual axis accelerometry, and one description of water swallow testing to be sensitive tools, but none were reported as consistently sensitive. A preponderance of identified studies was in post-stroke adults, limiting the generalizability of results. Conclusions No bedside screening protocol has been shown to provide adequate predictive value for presence of aspiration. Several individual exam maneuvers demonstrated reasonable sensitivity, but reproducibility and consistency of these protocols was not established. More research is needed to design an optimal protocol for dysphagia detection. PMID:25581840

Detection of allergen sources in the homes of sensitized children.

PubMed

Álvarez-Chávez, Clara R; Flores-Bernal, José L; Esquer-Peralta, Javier; Munguía-Vega, Nora E; Corella-Madueño, María A G; Rascón-Careaga, Antonio; Turcotte, David; Velázquez-Contreras, Luis E

2016-11-01

To identify the presence of environmental factors linked to the onset of allergies and asthma in the homes of children participating in an early detection program that were identified with sensitivity to common allergens in the region of Sonora, Mexico. A walkthrough assessment was carried out in the homes of sensitized children; the research tools were the questionnaire and environmental checklist proposed by the Lowell Healthy Homes Program of the University of Massachusetts-Lowell. The results showed the presence of environmental allergen sources, to which most of the children in the study are sensitized, as well as the environmental conditions and habits that determine the quality of the indoor air of the households, were both related to triggering allergies and asthma in this population. A statistically significant association was found between the visual observation of dust inside homes and the sensitivity of children to dust mites. Dust found inside the home was the most relevant environmental factor related to positive cases of IgE in children. Early detection of allergies in children in the study and the methodology used in this investigation provided a useful framework for the design of plans and intervention alternatives in these homes to prevent the development of allergies and asthma panorama. These plans should be designed with a multidisciplinary approach to impact social, environmental and economic benefits in the family, improving the living conditions of the study population and contributing to the sustainable development goals of the United Nations for 2030.

Sensitivity analysis and multidisciplinary optimization for aircraft design: Recent advances and results

NASA Technical Reports Server (NTRS)

Sobieszczanski-Sobieski, Jaroslaw

1988-01-01

Optimization by decomposition, complex system sensitivity analysis, and a rapid growth of disciplinary sensitivity analysis are some of the recent developments that hold promise of a quantum jump in the support engineers receive from computers in the quantitative aspects of design. Review of the salient points of these techniques is given and illustrated by examples from aircraft design as a process that combines the best of human intellect and computer power to manipulate data.

The relationship of ethics education to moral sensitivity and moral reasoning skills of nursing students.

PubMed

Park, Mihyun; Kjervik, Diane; Crandell, Jamie; Oermann, Marilyn H

2012-07-01

This study described the relationships between academic class and student moral sensitivity and reasoning and between curriculum design components for ethics education and student moral sensitivity and reasoning. The data were collected from freshman (n = 506) and senior students (n = 440) in eight baccalaureate nursing programs in South Korea by survey; the survey consisted of the Korean Moral Sensitivity Questionnaire and the Korean Defining Issues Test. The results showed that moral sensitivity scores in patient-oriented care and conflict were higher in senior students than in freshman students. Furthermore, more hours of ethics content were associated with higher principled thinking scores of senior students. Nursing education in South Korea may have an impact on developing student moral sensitivity. Planned ethics content in nursing curricula is necessary to improve moral sensitivity and moral reasoning of students.

Reusable Launch Vehicle Tank/Intertank Sizing Trade Study

NASA Technical Reports Server (NTRS)

Dorsey, John T.; Myers, David E.; Martin, Carl J.

2000-01-01

A tank and intertank sizing tool that includes effects of major design drivers, and which allows parametric studies to be performed, has been developed and calibrated against independent representative results. Although additional design features, such as bulkheads and field joints, are not currently included in the process, the improved level of fidelity has allowed parametric studies to be performed which have resulted in understanding of key tank and intertank design drivers, design sensitivities, and definition of preferred design spaces. The sizing results demonstrated that there were many interactions between the configuration parameters of internal/external payload, vehicle fineness ratio (half body angle), fuel arrangement (LOX-forward/LOX-aft), number of tanks, and tank shape/arrangement (number of lobes).

Design-Filter Selection for H2 Control of Microgravity Isolation Systems: A Single-Degree-of-Freedom Case Study

NASA Technical Reports Server (NTRS)

Hampton, R. David; Whorton, Mark S.

2000-01-01

Many microgravity space-science experiments require active vibration isolation, to attain suitably low levels of background acceleration for useful experimental results. The design of state-space controllers by optimal control methods requires judicious choices of frequency-weighting design filters. Kinematic coupling among states greatly clouds designer intuition in the choices of these filters, and the masking effects of the state observations cloud the process further. Recent research into the practical application of H2 synthesis methods to such problems, indicates that certain steps can lead to state frequency-weighting design-filter choices with substantially improved promise of usefulness, even in the face of these difficulties. In choosing these filters on the states, one considers their relationships to corresponding design filters on appropriate pseudo-sensitivity- and pseudo-complementary-sensitivity functions. This paper investigates the application of these considerations to a single-degree-of-freedom microgravity vibration-isolation test case. Significant observations that were noted during the design process are presented. along with explanations based on the existent theory for such problems.

SAFARI new and improved: extending the capabilities of SPICA's imaging spectrometer

NASA Astrophysics Data System (ADS)

Roelfsema, Peter; Giard, Martin; Najarro, Francisco; Wafelbakker, Kees; Jellema, Willem; Jackson, Brian; Sibthorpe, Bruce; Audard, Marc; Doi, Yasuo; di Giorgio, Anna; Griffin, Matthew; Helmich, Frank; Kamp, Inga; Kerschbaum, Franz; Meyer, Michael; Naylor, David; Onaka, Takashi; Poglitch, Albrecht; Spinoglio, Luigi; van der Tak, Floris; Vandenbussche, Bart

2014-08-01

The Japanese SPace Infrared telescope for Cosmology and Astrophysics, SPICA, aims to provide astronomers with a truly new window on the universe. With a large -3 meter class- cold -6K- telescope, the mission provides a unique low background environment optimally suited for highly sensitive instruments limited only by the cosmic background itself. SAFARI, the SpicA FAR infrared Instrument SAFARI, is a Fourier Transform imaging spectrometer designed to fully exploit this extremely low far infrared background environment. The SAFARI consortium, comprised of European and Canadian institutes, has established an instrument reference design based on a Mach-Zehnder interferometer stage with outputs directed to three extremely sensitive Transition Edge Sensor arrays covering the 35 to 210 μm domain. The baseline instrument provides R > 1000 spectroscopic imaging capabilities over a 2' by 2' field of view. A number of modifications to the instrument to extend its capabilities are under investigation. With the reference design SAFARI's sensitivity for many objects is limited not only by the detector NEP but also by the level of broad band background radiation - the zodiacal light for the shorter wavelengths and satellite baffle structures for the longer wavelengths. Options to reduce this background are dedicated masks or dispersive elements which can be inserted in the optics as required. The resulting increase in sensitivity can directly enhance the prime science goals of SAFARI; with the expected enhanced sensitivity astronomers would be in a better position to study thousands of galaxies out to redshift 3 and even many hundreds out to redshifts of 5 or 6. Possibilities to increase the wavelength resolution, at least for the shorter wavelength bands, are investigated as this would significantly enhance SAFARI's capabilities to study star and planet formation in our own galaxy.

Monte Carlo design of optimal wire mesh collimator for breast tumor imaging process

NASA Astrophysics Data System (ADS)

Saad, W. H. M.; Roslan, R. E.; Mahdi, M. A.; Choong, W.-S.; Saion, E.; Saripan, M. I.

2011-08-01

This paper presents the modeling of breast tumor imaging process using wire mesh collimator gamma camera. Previous studies showed that the wire mesh collimator has a potential to improve the sensitivity of the tumor detection. In this paper, we extend our research significantly, to find an optimal configuration of the wire mesh collimator specifically for semi-compressed breast tumor detection, by looking into four major factors: weight, sensitivity, spatial resolution and tumor contrast. The numbers of layers in the wire mesh collimator is varied to optimize the collimator design. The statistical variations of the results are studied by simulating multiple realizations for each experiment using different starting random numbers. All the simulation environments are modeled using Monte Carlo N-Particle Code (MCNP). The quality of the detection is measured directly by comparing the sensitivity, spatial resolution and tumor contrast of the images produced by the wire mesh collimator and benchmarked that with a standard multihole collimator. The proposed optimal configuration of the wire mesh collimator is optimized by selecting the number of layers in wire mesh collimator, where the tumor contrast shows a relatively comparable value to the multihole collimator, when it is tested with uniformly semi-compressed breast phantom. The wire mesh collimator showed higher number of sensitivity because of its loose arrangement while the spatial resolution of wire mesh collimator does not shows much different compared to the multihole collimator. With a relatively good tumor contrast and spatial resolution, and increased in sensitivity, a new proposed wire mesh collimator gives a significant improvement in the wire mesh collimator design for breast cancer imaging process. The proposed collimator configuration is reduced to 44.09% from the total multihole collimator weight.

Human Mars Lander Design for NASA's Evolvable Mars Campaign

NASA Technical Reports Server (NTRS)

Polsgrove, Tara; Chapman, Jack; Sutherlin, Steve; Taylor, Brian; Fabisinski, Leo; Collins, Tim; Cianciolo Dwyer, Alicia; Samareh, Jamshid; Robertson, Ed; Studak, Bill;

Low-sensitivity H ∞ filter design for linear delta operator systems with sampling time jitter

NASA Astrophysics Data System (ADS)

Guo, Xiang-Gui; Yang, Guang-Hong

2012-04-01

This article is concerned with the problem of designing H ∞ filters for a class of linear discrete-time systems with low-sensitivity to sampling time jitter via delta operator approach. Delta-domain model is used to avoid the inherent numerical ill-condition resulting from the use of the standard shift-domain model at high sampling rates. Based on projection lemma in combination with the descriptor system approach often used to solve problems related to delay, a novel bounded real lemma with three slack variables for delta operator systems is presented. A sensitivity approach based on this novel lemma is proposed to mitigate the effects of sampling time jitter on system performance. Then, the problem of designing a low-sensitivity filter can be reduced to a convex optimisation problem. An important consideration in the design of correlation filters is the optimal trade-off between the standard H ∞ criterion and the sensitivity of the transfer function with respect to sampling time jitter. Finally, a numerical example demonstrating the validity of the proposed design method is given.

Design Optimisation of a Magnetic Field Based Soft Tactile Sensor

PubMed Central

Raske, Nicholas; Kow, Junwai; Alazmani, Ali; Ghajari, Mazdak; Culmer, Peter; Hewson, Robert

2017-01-01

This paper investigates the design optimisation of a magnetic field based soft tactile sensor, comprised of a magnet and Hall effect module separated by an elastomer. The aim was to minimise sensitivity of the output force with respect to the input magnetic field; this was achieved by varying the geometry and material properties. Finite element simulations determined the magnetic field and structural behaviour under load. Genetic programming produced phenomenological expressions describing these responses. Optimisation studies constrained by a measurable force and stable loading conditions were conducted; these produced Pareto sets of designs from which the optimal sensor characteristics were selected. The optimisation demonstrated a compromise between sensitivity and the measurable force, a fabricated version of the optimised sensor validated the improvements made using this methodology. The approach presented can be applied in general for optimising soft tactile sensor designs over a range of applications and sensing modes. PMID:29099787

Preliminary Structural Sensitivity Study of Hypersonic Inflatable Aerodynamic Decelerator Using Probabilistic Methods

NASA Technical Reports Server (NTRS)

Lyle, Karen H.

2014-01-01

Acceptance of new spacecraft structural architectures and concepts requires validated design methods to minimize the expense involved with technology validation via flighttesting. This paper explores the implementation of probabilistic methods in the sensitivity analysis of the structural response of a Hypersonic Inflatable Aerodynamic Decelerator (HIAD). HIAD architectures are attractive for spacecraft deceleration because they are lightweight, store compactly, and utilize the atmosphere to decelerate a spacecraft during re-entry. However, designers are hesitant to include these inflatable approaches for large payloads or spacecraft because of the lack of flight validation. In the example presented here, the structural parameters of an existing HIAD model have been varied to illustrate the design approach utilizing uncertainty-based methods. Surrogate models have been used to reduce computational expense several orders of magnitude. The suitability of the design is based on assessing variation in the resulting cone angle. The acceptable cone angle variation would rely on the aerodynamic requirements.

Culture in Context: An Interdisciplinary Travel Study Course.

ERIC Educational Resources Information Center

Berger, Karen A.; O'Neill, Geraldine P.

2002-01-01

Describes an interdisciplinary travel study course designed to teach cultural appreciation and sensitivity in context. Readings and instruction focus on cultural issues that affect business and marketing practices, using France and the French as the subjects of the study. (Author/VWL)

On the design of wave digital filters with low sensitivity properties.

NASA Technical Reports Server (NTRS)

Renner, K.; Gupta, S. C.

1973-01-01

The wave digital filter patterned after doubly terminated maximum available power (MAP) networks by means of the Richard's transformation has been shown to have low-coefficient-sensitivity properties. This paper examines the exact nature of the relationship between the wave-digital-filter structure and the MAP networks and how the sensitivity property arises, which permits implementation of the digital structure with a lower coefficient word length than that possible with the conventional structures. The proper design procedure is specified and the nature of the unique complementary outputs is discussed. Finally, an example is considered which illustrates the design, the conversion techniques, and the low sensitivity properties.

Neuraminidase Subtyping of Avian Influenza Viruses with PrimerHunter-Designed Primers and Quadruplicate Primer Pools

PubMed Central

Huang, Yanyan; Khan, Mazhar; Măndoiu, Ion I.

2013-01-01

We have previously developed a software package called PrimerHunter to design primers for PCR-based virus subtyping. In this study, 9 pairs of primers were designed with PrimerHunter and successfully used to differentiate the 9 neuraminidase (NA) genes of avian influenza viruses (AIVs) in multiple PCR-based assays. Furthermore, primer pools were designed and successfully used to decrease the number of reactions needed for NA subtyping from 9 to 4. The quadruplicate primer-pool method is cost-saving, and was shown to be suitable for the NA subtyping of both cultured AIVs and uncultured AIV swab samples. The primers selected for this study showed excellent sensitivity and specificity in NA subtyping by RT-PCR, SYBR green-based Real-time PCR and Real-time RT-PCR methods. AIV RNA of 2 to 200 copies (varied by NA subtypes) could be detected by these reactions. No unspecific amplification was displayed when detecting RNAs of other avian infectious viruses such as Infectious bronchitis virus, Infectious bursal disease virus and Newcastle disease virus. In summary, this study introduced several sensitive and specific PCR-based assays for NA subtyping of AIVs and also validated again the effectiveness of the PrimerHunter tool for the design of subtyping primers. PMID:24312367

Making your skin crawl: The role of tactile sensitivity in disease avoidance.

PubMed

Hunt, David Francis; Cannell, Grace; Davenhill, Nicholas A; Horsford, Stephanie A; Fleischman, Diana S; Park, Justin H

2017-07-01

Mounting evidence indicates that animals, including humans, have evolved a behavioral disease-avoidance system designed to facilitate the detection and avoidance of sources of pathogens, and that this system interacts with physiological defenses. The skin acts as an important anatomical barrier, yet little research has investigated the role of tactile sensitivity in disease avoidance. Increased tactile sensitivity in the presence of potential sources of pathogens may facilitate prophylactic behaviors such as self-grooming. Across multiple studies, we tested the hypothesis that the induction of disgust-the key emotion underlying disease avoidance-may lead to greater tactile sensitivity compared to control conditions. A nonsignificant trend was found in a pilot study, which was replicated (and found to be significant) in Studies 1 and 2. To our knowledge, these results are the first to demonstrate disgust-induced changes in tactile sensitivity, and they contribute to the growing literature on the integrated evolved defenses against infectious disease. Copyright © 2017 Elsevier B.V. All rights reserved.

Aircraft Maneuvers for the Evaluation of Flying Qualities and Agility. Volume 2. Maneuver Descriptions and Section Guide

DTIC Science & Technology

1993-08-01

Requirements to Design 2 Several of these maneuvers may be suitable for the development of design criteria or tactical utility studies . However, this...research was not intended to be a criteria development effort or a tactical ufiflity study . Instead, a sensitivity between each maneuver and various...utility studies because it contains measure of merit data and pilot comments for numerous desigp parameter variations. The Standard Evaluation

Sensitivity of the Asteroid Redirect Robotic Mission (ARRM) to Launch Date and Asteroid Stay Time

NASA Technical Reports Server (NTRS)

Mcguire, Melissa L.; Burke, Laura M.; McCarty, Steven L.; Strange, Nathan J.; Qu, Min; Shen, Haijun; Vavrina, Matthew A.

2017-01-01

National Aeronautics and Space Administrations (NASAs) proposed Asteroid Redirect Mission (ARM) is being designed to robotically capture and then redirect an asteroidal boulder into a stable orbit in the vicinity of the moon, where astronauts would be able to visit and study it. The current reference trajectory for the robotic portion, ARRM, assumes a launch on a Delta-IV H in the end of the calendar year 2021, with a return for astronaut operations in cislunar space in 2026. The current baseline design allocates 245 days of stay time at the asteroid for operations and boulder collection. This paper outlines analysis completed by the ARRM mission design team to understand the sensitivity of the reference trajectory to launch date and asteroid stay time.

Sensitivity of the Asteroid Redirect Robotic Mission (ARRM) to Launch Date and Asteroid Stay Time

NASA Technical Reports Server (NTRS)

Mcguire, Melissa L.; Burke, Laura M.; McCarty, Steven L.; Strange, Nathan J.; Qu, Min; Shen, Haijun; Vavrina, Matthew A.

2017-01-01

National Aeronautics and Space Administrations (NASAs) proposed Asteroid Redirect Mission (ARM) is being designed to robotically capture and then redirect an asteroidal boulder mass into a stable orbit in the vicinity of the moon, where astronauts would be able to visit and study it. The current reference trajectory for the robotic portion, ARRM, assumes a launch on a Delta IV H in the end of the calendar year 2021, with a return for astronaut operations in cislunar space in 2026. The current baseline design allocates 245 days of stay time at the asteroid for operations and boulder collection. This paper outlines analysis completed by the ARRM mission design team to understand the sensitivity of the reference trajectory to launch date and asteroid stay time.

Application of Adjoint Methodology in Various Aspects of Sonic Boom Design

NASA Technical Reports Server (NTRS)

Rallabhandi, Sriram K.

2014-01-01

One of the advances in computational design has been the development of adjoint methods allowing efficient calculation of sensitivities in gradient-based shape optimization. This paper discusses two new applications of adjoint methodology that have been developed to aid in sonic boom mitigation exercises. In the first, equivalent area targets are generated using adjoint sensitivities of selected boom metrics. These targets may then be used to drive the vehicle shape during optimization. The second application is the computation of adjoint sensitivities of boom metrics on the ground with respect to parameters such as flight conditions, propagation sampling rate, and selected inputs to the propagation algorithms. These sensitivities enable the designer to make more informed selections of flight conditions at which the chosen cost functionals are less sensitive.

A methodological framework to support the initiation, design and institutionalization of participatory modeling processes in water resources management

NASA Astrophysics Data System (ADS)

Halbe, Johannes; Pahl-Wostl, Claudia; Adamowski, Jan

2018-01-01

Multiple barriers constrain the widespread application of participatory methods in water management, including the more technical focus of most water agencies, additional cost and time requirements for stakeholder involvement, as well as institutional structures that impede collaborative management. This paper presents a stepwise methodological framework that addresses the challenges of context-sensitive initiation, design and institutionalization of participatory modeling processes. The methodological framework consists of five successive stages: (1) problem framing and stakeholder analysis, (2) process design, (3) individual modeling, (4) group model building, and (5) institutionalized participatory modeling. The Management and Transition Framework is used for problem diagnosis (Stage One), context-sensitive process design (Stage Two) and analysis of requirements for the institutionalization of participatory water management (Stage Five). Conceptual modeling is used to initiate participatory modeling processes (Stage Three) and ensure a high compatibility with quantitative modeling approaches (Stage Four). This paper describes the proposed participatory model building (PMB) framework and provides a case study of its application in Québec, Canada. The results of the Québec study demonstrate the applicability of the PMB framework for initiating and designing participatory model building processes and analyzing barriers towards institutionalization.

Novel experimental design for high pressure-high temperature electrical resistance measurements in a "Paris-Edinburgh" large volume press.

PubMed

Matityahu, Shlomi; Emuna, Moran; Yahel, Eyal; Makov, Guy; Greenberg, Yaron

2015-04-01

We present a novel experimental design for high sensitivity measurements of the electrical resistance of samples at high pressures (0-6 GPa) and high temperatures (300-1000 K) in a "Paris-Edinburgh" type large volume press. Uniquely, the electrical measurements are carried out directly on a small sample, thus greatly increasing the sensitivity of the measurement. The sensitivity to even minor changes in electrical resistance can be used to clearly identify phase transitions in material samples. Electrical resistance measurements are relatively simple and rapid to execute and the efficacy of the present experimental design is demonstrated by measuring the electrical resistance of Pb, Sn, and Bi across a wide domain of temperature-pressure phase space and employing it to identify the loci of phase transitions. Based on these results, the phase diagrams of these elements are reconstructed to high accuracy and found to be in excellent agreement with previous studies. In particular, by mapping the locations of several well-studied reference points in the phase diagram of Sn and Bi, it is demonstrated that a standard calibration exists for the temperature and pressure, thus eliminating the need for direct or indirect temperature and pressure measurements. The present technique will allow simple and accurate mapping of phase diagrams under extreme conditions and may be of particular importance in advancing studies of liquid state anomalies.

Application of advanced technologies to small, short-haul transport aircraft (STAT)

NASA Technical Reports Server (NTRS)

Kraus, E. F.; Mall, O. D.; Awker, R. W.; Scholl, J. W.

1982-01-01

The benefits of selected advanced technologies for 19 and 30 passenger, short-haul aircraft were identified. Advanced technologies were investigated in four areas: aerodynamics, propulsion, structures, and ride quality. Configuration sensitivity studies were conducted to show design tradeoffs associated with passenger capacity, cabin comfort level, and design field length.

Statistical Power for Causally Defined Indirect Effects in Group-Randomized Trials with Individual-Level Mediators

ERIC Educational Resources Information Center

Kelcey, Benjamin; Dong, Nianbo; Spybrook, Jessaca; Cox, Kyle

2017-01-01

Designs that facilitate inferences concerning both the total and indirect effects of a treatment potentially offer a more holistic description of interventions because they can complement "what works" questions with the comprehensive study of the causal connections implied by substantive theories. Mapping the sensitivity of designs to…

Designing Multi-Channel Web Frameworks for Cultural Tourism Applications: The MUSE Case Study.

ERIC Educational Resources Information Center

Garzotto, Franca; Salmon, Tullio; Pigozzi, Massimiliano

A framework for the design of multi-channel (MC) applications in the cultural tourism domain is presented. Several heterogeneous interface devices are supported including location-sensitive mobile units, on-site stationary devices, and personalized CDs that extend the on-site experience beyond the visit time thanks to personal memories gathered…

PERFORMANCE OF OVID MEDLINE SEARCH FILTERS TO IDENTIFY HEALTH STATE UTILITY STUDIES.

PubMed

Arber, Mick; Garcia, Sonia; Veale, Thomas; Edwards, Mary; Shaw, Alison; Glanville, Julie M

2017-01-01

This study was designed to assess the sensitivity of three Ovid MEDLINE search filters developed to identify studies reporting health state utility values (HSUVs), to improve the performance of the best performing filter, and to validate resulting search filters. Three quasi-gold standard sets (QGS1, QGS2, QGS3) of relevant studies were harvested from reviews of studies reporting HSUVs. The performance of three initial filters was assessed by measuring their relative recall of studies in QGS1. The best performing filter was then developed further using QGS2. This resulted in three final search filters (FSF1, FSF2, and FSF3), which were validated using QGS3. FSF1 (sensitivity maximizing) retrieved 132/139 records (sensitivity: 95 percent) in the QGS3 validation set. FSF1 had a number needed to read (NNR) of 842. FSF2 (balancing sensitivity and precision) retrieved 128/139 records (sensitivity: 92 percent) with a NNR of 502. FSF3 (precision maximizing) retrieved 123/139 records (sensitivity: 88 percent) with a NNR of 383. We have developed and validated a search filter (FSF1) to identify studies reporting HSUVs with high sensitivity (95 percent) and two other search filters (FSF2 and FSF3) with reasonably high sensitivity (92 percent and 88 percent) but greater precision, resulting in a lower NNR. These seem to be the first validated filters available for HSUVs. The availability of filters with a range of sensitivity and precision options enables researchers to choose the filter which is most appropriate to the resources available for their specific research.

Aerodynamic shape optimization directed toward a supersonic transport using sensitivity analysis

NASA Technical Reports Server (NTRS)

Baysal, Oktay

1995-01-01

This investigation was conducted from March 1994 to August 1995, primarily, to extend and implement the previously developed aerodynamic design optimization methodologies for the problems related to a supersonic transport design. These methods had demonstrated promise to improve the designs (more specifically, the shape) of aerodynamic surfaces, by coupling optimization algorithms (OA) with Computational Fluid Dynamics (CFD) algorithms via sensitivity analyses (SA) with surface definition methods from Computer Aided Design (CAD). The present extensions of this method and their supersonic implementations have produced wing section designs, delta wing designs, cranked-delta wing designs, and nacelle designs, all of which have been reported in the open literature. Despite the fact that these configurations were highly simplified to be of any practical or commercial use, they served the algorithmic and proof-of-concept objectives of the study very well. The primary cause for the configurational simplifications, other than the usual simplify-to-study the fundamentals reason, were the premature closing of the project. Only after the first of the originally intended three-year term, both the funds and the computer resources supporting the project were abruptly cut due to their severe shortages at the funding agency. Nonetheless, it was shown that the extended methodologies could be viable options in optimizing the design of not only an isolated single-component configuration, but also a multiple-component configuration in supersonic and viscous flow. This allowed designing with the mutual interference of the components being one of the constraints all along the evolution of the shapes.

Development of a Multilevel Optimization Approach to the Design of Modern Engineering Systems. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Barthelemy, J. F. M.

1983-01-01

A general algorithm is proposed which carries out the design process iteratively, starting at the top of the hierarchy and proceeding downward. Each subproblem is optimized separately for fixed controls from higher level subproblems. An optimum sensitivity analysis is then performed which determines the sensitivity of the subproblem design to changes in higher level subproblem controls. The resulting sensitivity derivatives are used to construct constraints which force the controlling subproblems into chosing their own designs so as to improve the lower levels subproblem designs while satisfying their own constraints. The applicability of the proposed algorithm is demonstrated by devising a four-level hierarchy to perform the simultaneous aerodynamic and structural design of a high-performance sailplane wing for maximum cross-country speed. Finally, the concepts discussed are applied to the two-level minimum weight structural design of the sailplane wing. The numerical experiments show that discontinuities in the sensitivity derivatives may delay convergence, but that the algorithm is robust enough to overcome these discontinuities and produce low-weight feasible designs, regardless of whether the optimization is started from the feasible space or the infeasible one.

Design of a Physiology-Sensitive VR-Based Social Communication Platform for Children With Autism.

PubMed

Kuriakose, Selvia; Lahiri, Uttama

2017-08-01

Individuals with autism are often characterized by impairments in communication, reciprocal social interaction and explicit expression of their affective states. In conventional techniques, a therapist adjusts the intervention paradigm by monitoring the affective state e.g., anxiety of these individuals for effective floor-time-therapy. Conventional techniques, though powerful, are observation-based and face resource limitations. Technology-assisted systems can provide a quantitative, individualized rehabilitation platform. Presently-available systems are designed primarily to chain learning via aspects of one's performance alone restricting individualization. Specifically, these systems are not sensitive to one's anxiety. Our presented work seeks to bridge this gap by developing a novel VR-based interactive system with Anxiety-Sensitive adaptive technology. Specifically, such a system is capable of objectively identifying and quantifying one's anxiety level from real-time biomarkers, along with performance metrics. In turn it can adaptively respond in an individualized manner to foster improved social communication skills. In our present research, we have used Virtual Reality (VR) to design a proof-of-concept application that exposes participants to social tasks of varying challenges. Results of a preliminary usability study indicate the potential of our VR-based Anxiety-Sensitive system to foster improved task performance, thereby serving as a potent complementary tool in the hands of therapist.

Booster propulsion/vehicle impact study

NASA Technical Reports Server (NTRS)

Weldon, Vincent; Dunn, Michael; Fink, Lawrence; Phillips, Dwight; Wetzel, Eric

1988-01-01

The use of hydrogen RP-1, propane, and methane as fuels for booster engines of launch vehicles is discussed. An automated procedure for integrated launch vehicle, engine sizing, and design optimization was used to define two stage and single stage concepts for minimum dry weight. The two stage vehicles were unmanned and used a flyback booster and partially reusable orbiter. The single stage designs were fully reusable, manned flyback vehicles. Comparisons of these vehicle designs, showing the effects of using different fuels, as well as sensitivity and trending data, are presented. In addition, the automated design technique utilized for the study is described.

Sensitivity method for integrated structure/active control law design

NASA Technical Reports Server (NTRS)

Gilbert, Michael G.

1987-01-01

The development is described of an integrated structure/active control law design methodology for aeroelastic aircraft applications. A short motivating introduction to aeroservoelasticity is given along with the need for integrated structures/controls design algorithms. Three alternative approaches to development of an integrated design method are briefly discussed with regards to complexity, coordination and tradeoff strategies, and the nature of the resulting solutions. This leads to the formulation of the proposed approach which is based on the concepts of sensitivity of optimum solutions and multi-level decompositions. The concept of sensitivity of optimum is explained in more detail and compared with traditional sensitivity concepts of classical control theory. The analytical sensitivity expressions for the solution of the linear, quadratic cost, Gaussian (LQG) control problem are summarized in terms of the linear regulator solution and the Kalman Filter solution. Numerical results for a state space aeroelastic model of the DAST ARW-II vehicle are given, showing the changes in aircraft responses to variations of a structural parameter, in this case first wing bending natural frequency.

Efficient Simulation of Wing Modal Response: Application of 2nd Order Shape Sensitivities and Neural Networks

NASA Technical Reports Server (NTRS)

Kapania, Rakesh K.; Liu, Youhua

2000-01-01

At the preliminary design stage of a wing structure, an efficient simulation, one needing little computation but yielding adequately accurate results for various response quantities, is essential in the search of optimal design in a vast design space. In the present paper, methods of using sensitivities up to 2nd order, and direct application of neural networks are explored. The example problem is how to decide the natural frequencies of a wing given the shape variables of the structure. It is shown that when sensitivities cannot be obtained analytically, the finite difference approach is usually more reliable than a semi-analytical approach provided an appropriate step size is used. The use of second order sensitivities is proved of being able to yield much better results than the case where only the first order sensitivities are used. When neural networks are trained to relate the wing natural frequencies to the shape variables, a negligible computation effort is needed to accurately determine the natural frequencies of a new design.

Development of a generalized perturbation theory method for sensitivity analysis using continuous-energy Monte Carlo methods

DOE PAGES

Perfetti, Christopher M.; Rearden, Bradley T.

2016-03-01

The sensitivity and uncertainty analysis tools of the ORNL SCALE nuclear modeling and simulation code system that have been developed over the last decade have proven indispensable for numerous application and design studies for nuclear criticality safety and reactor physics. SCALE contains tools for analyzing the uncertainty in the eigenvalue of critical systems, but cannot quantify uncertainty in important neutronic parameters such as multigroup cross sections, fuel fission rates, activation rates, and neutron fluence rates with realistic three-dimensional Monte Carlo simulations. A more complete understanding of the sources of uncertainty in these design-limiting parameters could lead to improvements in processmore » optimization, reactor safety, and help inform regulators when setting operational safety margins. A novel approach for calculating eigenvalue sensitivity coefficients, known as the CLUTCH method, was recently explored as academic research and has been found to accurately and rapidly calculate sensitivity coefficients in criticality safety applications. The work presented here describes a new method, known as the GEAR-MC method, which extends the CLUTCH theory for calculating eigenvalue sensitivity coefficients to enable sensitivity coefficient calculations and uncertainty analysis for a generalized set of neutronic responses using high-fidelity continuous-energy Monte Carlo calculations. Here, several criticality safety systems were examined to demonstrate proof of principle for the GEAR-MC method, and GEAR-MC was seen to produce response sensitivity coefficients that agreed well with reference direct perturbation sensitivity coefficients.« less

The impact of cultural diversity forum on students' openness to diversity.

PubMed

Sanner, Susan; Baldwin, Dee; Cannella, Kathleen A S; Charles, Jennell; Parker, Lillian

2010-01-01

As the population demographics for the United States (U.S.) shift towards increasing diversity, it is essential that nurses provide culturally competent care. Cultural sensitivity has been identified as a major curricular element in the American Association of Colleges of Nursing's (AACN) The Essentials of Baccalaureate Education for Professional Nursing Practice. Thus it is imperative that nursing faculty use effective strategies to help nursing students develop cultural sensitivity and competence. Educational workshops focusing on cultural diversity are usually designed to increase people's cultural sensitivity. The purpose of this study was to assess the effectiveness of a cultural diversity forum on nursing students' cultural sensitivity as measured by their openness to diversity. A convenience sample of students was recruited from a public university in the southeastern United States. The workshop was designed as a forum that combined a keynote presentation, shared meal, and a small group interactional activity. Cultural sensitivity was measured using the Openness to Diversity/Challenge Scale (ODCS), and was administered to students before and after the forum. A convenience sample of 47 students agreed to participate and completed both the pretest and posttest. Following the workshop, the students had more cultural sensitivity as measured by their scores on the ODCS (Wilcoxin Signed-Rank test z= -3.286, p = 0.001). The findings suggested that an educational format like the cultural diversity forum can promote students' cultural sensitivity. Further research needs to continue to focus on the effectiveness of strategies to increase the cultural sensitivity of baccalaureate nursing students.

Nursing students' understanding of factors influencing ethical sensitivity: A qualitative study.

PubMed

Borhani, Fariba; Abbaszadeh, Abbas; Mohsenpour, Mohaddeseh

2013-07-01

Ethical sensitivity is considered as a component of professional competency of nurses. Its effects on improvement of nurses' ethical performance and the therapeutic relationship between nurses and patients have been reported. However, very limited studies have evaluated ethical sensitivity. Since no previous Iranian research has been conducted in this regard, the present study aimed to review nursing students' understanding of effective factors on ethical sensitivity. This qualitative study was performed in Kerman, Iran, during 2009. It used semi-structured individual interviews with eight MSc nursing students to assess their viewpoints. It also included two focus groups. Purposive sampling was continued until data saturation. Data were analyzed using manifest content analysis. The students' understanding of factors influencing ethical sensitivity were summarized in five main themes including individual and spiritual characteristics, education, mutual understanding, internal and external controls, and experience of an immoral act. The findings of this study create a unique framework for sensitization of nurses in professional performance. The application of these factors in human resource management is reinforcement of positive aspects and decrease in negative aspects, in education can use for educational objectives setting, and in research can designing studies based on this framework and making related tools. It is noteworthy that presented classification was influenced by students themselves and mentioned to a kind of learning activity by them.

High-Sensitivity and Low-Hysteresis Porous MIM-Type Capacitive Humidity Sensor Using Functional Polymer Mixed with TiO2 Microparticles

PubMed Central

Liu, Ming-Qing; Wang, Cong; Kim, Nam-Young

2017-01-01

In this study, a high-sensitivity and low-hysteresis porous metal–insulator–metal-type capacitive humidity sensor is investigated using a functional polymer mixed with TiO2 microparticles. The humidity sensor consists of an optimally designed porous top electrode, a functional polymer humidity sensitive layer, a bottom electrode, and a glass substrate. The porous top electrode is designed to increase the contact area between the sensing layer and water vapor, leading to high sensitivity and quick response time. The functional polymer mixed with TiO2 microparticles shows excellent hysteresis under a wide humidity-sensing range with good long-term stability. The results show that as the relative humidity ranges from 10% RH to 90% RH, the proposed humidity sensor achieves a high sensitivity of 0.85 pF/% RH and a fast response time of less than 35 s. Furthermore, the sensor shows an ultra-low hysteresis of 0.95% RH at 60% RH, a good temperature dependence, and a stable capacitance value with a maximum of 0.17% RH drift during 120 h of continuous test. PMID:28157167

Methylation-Sensitive High Resolution Melting (MS-HRM).

PubMed

Hussmann, Dianna; Hansen, Lise Lotte

2018-01-01

Methylation-Sensitive High Resolution Melting (MS-HRM) is an in-tube, PCR-based method to detect methylation levels at specific loci of interest. A unique primer design facilitates a high sensitivity of the assays enabling detection of down to 0.1-1% methylated alleles in an unmethylated background.Primers for MS-HRM assays are designed to be complementary to the methylated allele, and a specific annealing temperature enables these primers to anneal both to the methylated and the unmethylated alleles thereby increasing the sensitivity of the assays. Bisulfite treatment of the DNA prior to performing MS-HRM ensures a different base composition between methylated and unmethylated DNA, which is used to separate the resulting amplicons by high resolution melting.The high sensitivity of MS-HRM has proven useful for detecting cancer biomarkers in a noninvasive manner in urine from bladder cancer patients, in stool from colorectal cancer patients, and in buccal mucosa from breast cancer patients. MS-HRM is a fast method to diagnose imprinted diseases and to clinically validate results from whole-epigenome studies. The ability to detect few copies of methylated DNA makes MS-HRM a key player in the quest for establishing links between environmental exposure, epigenetic changes, and disease.

Modeling the Sensitivity of Field Surveys for Detection of Environmental DNA (eDNA)

PubMed Central

Schultz, Martin T.; Lance, Richard F.

2015-01-01

The environmental DNA (eDNA) method is the practice of collecting environmental samples and analyzing them for the presence of a genetic marker specific to a target species. Little is known about the sensitivity of the eDNA method. Sensitivity is the probability that the target marker will be detected if it is present in the water body. Methods and tools are needed to assess the sensitivity of sampling protocols, design eDNA surveys, and interpret survey results. In this study, the sensitivity of the eDNA method is modeled as a function of ambient target marker concentration. The model accounts for five steps of sample collection and analysis, including: 1) collection of a filtered water sample from the source; 2) extraction of DNA from the filter and isolation in a purified elution; 3) removal of aliquots from the elution for use in the polymerase chain reaction (PCR) assay; 4) PCR; and 5) genetic sequencing. The model is applicable to any target species. For demonstration purposes, the model is parameterized for bighead carp (Hypophthalmichthys nobilis) and silver carp (H. molitrix) assuming sampling protocols used in the Chicago Area Waterway System (CAWS). Simulation results show that eDNA surveys have a high false negative rate at low concentrations of the genetic marker. This is attributed to processing of water samples and division of the extraction elution in preparation for the PCR assay. Increases in field survey sensitivity can be achieved by increasing sample volume, sample number, and PCR replicates. Increasing sample volume yields the greatest increase in sensitivity. It is recommended that investigators estimate and communicate the sensitivity of eDNA surveys to help facilitate interpretation of eDNA survey results. In the absence of such information, it is difficult to evaluate the results of surveys in which no water samples test positive for the target marker. It is also recommended that invasive species managers articulate concentration-based sensitivity objectives for eDNA surveys. In the absence of such information, it is difficult to design appropriate sampling protocols. The model provides insights into how sampling protocols can be designed or modified to achieve these sensitivity objectives. PMID:26509674

Modeling the Sensitivity of Field Surveys for Detection of Environmental DNA (eDNA).

PubMed

Schultz, Martin T; Lance, Richard F

2015-01-01

The environmental DNA (eDNA) method is the practice of collecting environmental samples and analyzing them for the presence of a genetic marker specific to a target species. Little is known about the sensitivity of the eDNA method. Sensitivity is the probability that the target marker will be detected if it is present in the water body. Methods and tools are needed to assess the sensitivity of sampling protocols, design eDNA surveys, and interpret survey results. In this study, the sensitivity of the eDNA method is modeled as a function of ambient target marker concentration. The model accounts for five steps of sample collection and analysis, including: 1) collection of a filtered water sample from the source; 2) extraction of DNA from the filter and isolation in a purified elution; 3) removal of aliquots from the elution for use in the polymerase chain reaction (PCR) assay; 4) PCR; and 5) genetic sequencing. The model is applicable to any target species. For demonstration purposes, the model is parameterized for bighead carp (Hypophthalmichthys nobilis) and silver carp (H. molitrix) assuming sampling protocols used in the Chicago Area Waterway System (CAWS). Simulation results show that eDNA surveys have a high false negative rate at low concentrations of the genetic marker. This is attributed to processing of water samples and division of the extraction elution in preparation for the PCR assay. Increases in field survey sensitivity can be achieved by increasing sample volume, sample number, and PCR replicates. Increasing sample volume yields the greatest increase in sensitivity. It is recommended that investigators estimate and communicate the sensitivity of eDNA surveys to help facilitate interpretation of eDNA survey results. In the absence of such information, it is difficult to evaluate the results of surveys in which no water samples test positive for the target marker. It is also recommended that invasive species managers articulate concentration-based sensitivity objectives for eDNA surveys. In the absence of such information, it is difficult to design appropriate sampling protocols. The model provides insights into how sampling protocols can be designed or modified to achieve these sensitivity objectives.

Specific coil design for SENSE: a six-element cardiac array.

PubMed

Weiger, M; Pruessmann, K P; Leussler, C; Röschmann, P; Boesiger, P

2001-03-01

In sensitivity encoding (SENSE), the effects of inhomogeneous spatial sensitivity of surface coils are utilized for signal localization in addition to common Fourier encoding using magnetic field gradients. Unlike standard Fourier MRI, SENSE images exhibit an inhomogeneous noise distribution, which crucially depends on the geometrical sensitivity relations of the coils used. Thus, for optimum signal-to-noise-ratio (SNR) and noise homogeneity, specialized coil configurations are called for. In this article we study the implications of SENSE imaging for coil layout by means of simulations and imaging experiments in a phantom and in vivo. New, specific design principles are identified. For SENSE imaging, the elements of a coil array should be smaller than for common phased-array imaging. Furthermore, adjacent coil elements should not overlap. Based on the findings of initial investigations, a configuration of six coils was designed and built specifically for cardiac applications. The in vivo evaluation of this array showed a considerable SNR increase in SENSE images, as compared with a conventional array. Magn Reson Med 45:495-504, 2001. Copyright 2001 Wiley-Liss, Inc.

One size does not fit all: investigating doctors' stated preference heterogeneity for job incentives to inform policy in Thailand.

PubMed

Lagarde, Mylene; Pagaiya, Nonglak; Tangcharoensathian, Viroj; Blaauw, Duane

2013-12-01

This study investigates heterogeneity in Thai doctors' job preferences at the beginning of their career, with a view to inform the design of effective policies to retain them in rural areas. A discrete choice experiment was designed and administered to 198 young doctors. We analysed the data using several specifications of a random parameter model to account for various sources of preference heterogeneity. By modelling preference heterogeneity, we showed how sensitivity to different incentives varied in different sections of the population. In particular, doctors from rural backgrounds were more sensitive than others to a 45% salary increase and having a post near their home province, but they were less sensitive to a reduction in the number of on-call nights. On the basis of the model results, the effects of two types of interventions were simulated: introducing various incentives and modifying the population structure. The results of the simulations provide multiple elements for consideration for policy-makers interested in designing effective interventions. They also underline the interest of modelling preference heterogeneity carefully. Copyright © 2013 John Wiley & Sons, Ltd.

The Influence of PV Module Materials and Design on Solder Joint Thermal Fatigue Durability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bosco, Nick; Silverman, Timothy J.; Kurtz, Sarah

Finite element model (FEM) simulations have been performed to elucidate the effect of flat plate photovoltaic (PV) module materials and design on PbSn eutectic solder joint thermal fatigue durability. The statistical method of Latin Hypercube sampling was employed to investigate the sensitivity of simulated damage to each input variable. Variables of laminate material properties and their thicknesses were investigated. Using analysis of variance, we determined that the rate of solder fatigue was most sensitive to solder layer thickness, with copper ribbon and silicon thickness being the next two most sensitive variables. By simulating both accelerated thermal cycles (ATCs) and PVmore » cell temperature histories through two characteristic days of service, we determined that the acceleration factor between the ATC and outdoor service was independent of the variables sampled in this study. This result implies that an ATC test will represent a similar time of outdoor exposure for a wide range of module designs. This is an encouraging result for the standard ATC that must be universally applied across all modules.« less

Optimization and Validation of a Sensitive Method for HPLC-PDA Simultaneous Determination of Torasemide and Spironolactone in Human Plasma using Central Composite Design.

PubMed

Subramanian, Venkatesan; Nagappan, Kannappan; Sandeep Mannemala, Sai

2015-01-01

A sensitive, accurate, precise and rapid HPLC-PDA method was developed and validated for the simultaneous determination of torasemide and spironolactone in human plasma using Design of experiments. Central composite design was used to optimize the method using content of acetonitrile, concentration of buffer and pH of mobile phase as independent variables, while the retention factor of spironolactone, resolution between torasemide and phenobarbitone; and retention time of phenobarbitone were chosen as dependent variables. The chromatographic separation was achieved on Phenomenex C(18) column and the mobile phase comprising 20 mM potassium dihydrogen ortho phosphate buffer (pH-3.2) and acetonitrile in 82.5:17.5 v/v pumped at a flow rate of 1.0 mL min(-1). The method was validated according to USFDA guidelines in terms of selectivity, linearity, accuracy, precision, recovery and stability. The limit of quantitation values were 80 and 50 ng mL(-1) for torasemide and spironolactone respectively. Furthermore, the sensitivity and simplicity of the method suggests the validity of method for routine clinical studies.

A stereo-compound hybrid microscope for combined intracellular and optical recording of invertebrate neural network activity

PubMed Central

Frost, William N.; Wang, Jean; Brandon, Christopher J.

2007-01-01

Optical recording studies of invertebrate neural networks with voltage-sensitive dyes seldom employ conventional intracellular electrodes. This may in part be due to the traditional reliance on compound microscopes for such work. While such microscopes have high light-gathering power, they do not provide depth of field, making working with sharp electrodes difficult. Here we describe a hybrid microscope design, with switchable compound and stereo objectives, that eases the use of conventional intracellular electrodes in optical recording experiments. We use it, in combination with a voltage-sensitive dye and photodiode array, to identify neurons participating in the swim motor program of the marine mollusk Tritonia. This microscope design should be applicable to optical recording studies in many preparations. PMID:17306887

Observed sensitivity during family interactions and cumulative risk: A study of multiple dyads per family.

PubMed

Browne, Dillon T; Leckie, George; Prime, Heather; Perlman, Michal; Jenkins, Jennifer M

2016-07-01

The present study sought to investigate the family, individual, and dyad-specific contributions to observed cognitive sensitivity during family interactions. Moreover, the influence of cumulative risk on sensitivity at the aforementioned levels of the family was examined. Mothers and 2 children per family were observed interacting in a round robin design (i.e., mother-older sibling, mother younger-sibling and sibling-dyad, N = 385 families). Data were dyadic, in that there were 2 directional scores per interaction, and were analyzed using a multilevel formulation of the Social Relations Model. Variance partitioning revealed that cognitive sensitivity is simultaneously a function of families, individuals and dyads, though the importance of these components varies across family roles. Cognitive sensitivity for mothers was primarily attributable to individual differences, whereas cognitive sensitivity for children was predominantly attributable to family and dyadic differences, especially for youngest children. Cumulative risk explained family and individual variance in cognitive sensitivity, particularly when actors were older or in a position of relative competence or authority (i.e., mother to children, older to younger siblings). Overall, this study demonstrates that cognitive sensitivity operates across levels of family organization, and is negatively impacted by psychosocial risk. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

A Quad-Cantilevered Plate micro-sensor for intracranial pressure measurement.

PubMed

Lalkov, Vasko; Qasaimeh, Mohammad A

2017-07-01

This paper proposes a new design for pressure-sensing micro-plate platform to bring higher sensitivity to a pressure sensor based on piezoresistive MEMS sensing mechanism. The proposed design is composed of a suspended plate having four stepped cantilever beams connected to its corners, and thus defined as Quad-Cantilevered Plate (QCP). Finite element analysis was performed to determine the optimal design for sensitivity and structural stability under a range of applied forces. Furthermore, a piezoresistive analysis was performed to calculate sensor sensitivity. Both the maximum stress and the change in resistance of the piezoresistor associated with the QCP were found to be higher compared to previously published designs, and linearly related to the applied pressure as desired. Therefore, the QCP demonstrates greater sensitivity, and could be potentially used as an efficient pressure sensor for intracranial pressure measurement.

Multidisciplinary Analysis and Optimal Design: As Easy as it Sounds?

NASA Technical Reports Server (NTRS)

Moore, Greg; Chainyk, Mike; Schiermeier, John

2004-01-01

The viewgraph presentation examines optimal design for precision, large aperture structures. Discussion focuses on aspects of design optimization, code architecture and current capabilities, and planned activities and collaborative area suggestions. The discussion of design optimization examines design sensitivity analysis; practical considerations; and new analytical environments including finite element-based capability for high-fidelity multidisciplinary analysis, design sensitivity, and optimization. The discussion of code architecture and current capabilities includes basic thermal and structural elements, nonlinear heat transfer solutions and process, and optical modes generation.

Diagnostic accuracy of fundal height and handheld ultrasound-measured abdominal circumference to screen for fetal growth abnormalities

PubMed Central

Haragan, Adriane F.; Hulsey, Thomas C.; Hawk, Angela F.; Newman, Roger B.; Chang, Eugene Y.

2015-01-01

OBJECTIVE We sought to compare fundal height and handheld ultrasound–measured fetal abdominal circumference (HHAC) for the prediction of fetal growth restriction (FGR) or large for gestational age. STUDY DESIGN This was a diagnostic accuracy study in nonanomalous singleton pregnancies between 24 and 40 weeks’ gestation. Patients underwent HHAC and fundal height measurement prior to formal growth ultrasound. FGR was defined as estimated fetal weight less than 10%, whereas large for gestational age was defined as estimated fetal weight greater than 90%. Sensitivity and specificity were calculated and compared using methods described elsewhere. RESULTS There were 251 patients included in this study. HHAC had superior sensitivity and specificity for the detection of FGR (sensitivity, 100% vs 42.86%) and (specificity, 92.62% vs 85.24%). HHAC had higher specificity but lower sensitivity when screening for LGA (specificity, 85.66% vs 66.39%) and (sensitivity, 57.14% vs 71.43%). CONCLUSION HHAC could prove to be a valuable screening tool in the detection of FGR. Further studies are needed in a larger population. PMID:25818672

Nuclear Thermal Propulsion Mars Mission Systems Analysis and Requirements Definition

NASA Technical Reports Server (NTRS)

Mulqueen, Jack; Chiroux, Robert C.; Thomas, Dan; Crane, Tracie

2007-01-01

This paper describes the Mars transportation vehicle design concepts developed by the Marshall Space Flight Center (MSFC) Advanced Concepts Office. These vehicle design concepts provide an indication of the most demanding and least demanding potential requirements for nuclear thermal propulsion systems for human Mars exploration missions from years 2025 to 2035. Vehicle concept options vary from large "all-up" vehicle configurations that would transport all of the elements for a Mars mission on one vehicle. to "split" mission vehicle configurations that would consist of separate smaller vehicles that would transport cargo elements and human crew elements to Mars separately. Parametric trades and sensitivity studies show NTP stage and engine design options that provide the best balanced set of metrics based on safety, reliability, performance, cost and mission objectives. Trade studies include the sensitivity of vehicle performance to nuclear engine characteristics such as thrust, specific impulse and nuclear reactor type. Tbe associated system requirements are aligned with the NASA Exploration Systems Mission Directorate (ESMD) Reference Mars mission as described in the Explorations Systems Architecture Study (ESAS) report. The focused trade studies include a detailed analysis of nuclear engine radiation shield requirements for human missions and analysis of nuclear thermal engine design options for the ESAS reference mission.

LIGO: The instruments that launched gravitational-wave astronomy

NASA Astrophysics Data System (ADS)

Fritschel, Peter; LIGO Scientific Collaboration

2018-01-01

After decades of development, the advanced gravitational wave detectors are now in the business of making detections of the types of astrophysical sources they were designed for. And yet these detectors still have a ways to go to reach their designed sensitivity levels. This talk will cover the design and performance of these advanced detectors, with emphasis on Advanced LIGO. I will lay out the path to reaching design sensitivity, and then turn to plans for future improvements to the existing LIGO detectors’ sensitivity. Looking even further into the future, I will discuss concepts for a new generation of detectors that will be needed to probe much deeper into the cosmos.

An experimental test of the effect of acute anxious arousal and anxiety sensitivity on negative reinforcement smoking.

PubMed

Farris, Samantha G; Zvolensky, Michael J

2016-07-01

Although anxiety sensitivity has been reliably associated with smoking-anxiety comorbidity, there has not been a test of whether this construct moderates the effect of acute anxious arousal on actual smoking behavior. The present study utilized an experimental design to test the moderating role of anxiety sensitivity on laboratory-induced anxious arousal in terms of smoking urges and topography (puff style). Participants were adult daily smokers (n=90; Mage=43.6 SD =9.7); average 15.8 cigarettes per day). A between-subjects design was used; participants were randomly assigned to complete a biological challenge procedure consisting of either a single vital capacity inhalation of 35% carbon dioxide (CO2)-enriched air mixture or compressed room air. Smoking urges and smoking topography (puff behavior) were assessed before and after the challenge. Results revealed a significant interaction between anxiety sensitivity and experimental condition (b=-9.96, p=0.014), such that high anxiety sensitive smokers exposed to 35% CO2-enriched air reported significantly lower levels of smoking urges, relative to low anxiety sensitive smokers; the conditional effect of anxiety sensitivity was not observed for the room air condition. There were no significant interaction effects of experimental manipulation by anxiety sensitivity for any of the smoking topography outcomes. The present results suggest for smokers with higher levels of anxiety sensitivity, the acute experience of anxious arousal is related to decreased subjective smoking urges. These data invite future research to explore the reasons for dampened smoking urges, including cardiorespiratory symptom severity. © The Author(s) 2016.

A sensitivity analysis for missing outcomes due to truncation by death under the matched-pairs design.

PubMed

Imai, Kosuke; Jiang, Zhichao

2018-04-29

The matched-pairs design enables researchers to efficiently infer causal effects from randomized experiments. In this paper, we exploit the key feature of the matched-pairs design and develop a sensitivity analysis for missing outcomes due to truncation by death, in which the outcomes of interest (e.g., quality of life measures) are not even well defined for some units (e.g., deceased patients). Our key idea is that if 2 nearly identical observations are paired prior to the randomization of the treatment, the missingness of one unit's outcome is informative about the potential missingness of the other unit's outcome under an alternative treatment condition. We consider the average treatment effect among always-observed pairs (ATOP) whose units exhibit no missing outcome regardless of their treatment status. The naive estimator based on available pairs is unbiased for the ATOP if 2 units of the same pair are identical in terms of their missingness patterns. The proposed sensitivity analysis characterizes how the bounds of the ATOP widen as the degree of the within-pair similarity decreases. We further extend the methodology to the matched-pairs design in observational studies. Our simulation studies show that informative bounds can be obtained under some scenarios when the proportion of missing data is not too large. The proposed methodology is also applied to the randomized evaluation of the Mexican universal health insurance program. An open-source software package is available for implementing the proposed research. Copyright © 2018 John Wiley & Sons, Ltd.

Design Flexibility for Uncertain Distributed Generation from Photovoltaics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Palmintier, Bryan; Krishnamurthy, Dheepak; Wu, Hongyu

2016-12-12

Uncertainty in the future adoption patterns for distributed energy resources (DERs) introduces a challenge for electric distribution system planning. This paper explores the potential for flexibility in design - also known as real options - to identify design solutions that may never emerge when future DER patterns are treated as deterministic. A test case for storage system design with uncertain distributed generation for solar photovoltaics (DGPV) demonstrates this approach and is used to study sensitivities to a range of techno-economic assumptions.

Wide field/planetary camera optics study. [for the large space telescope

NASA Technical Reports Server (NTRS)

1979-01-01

Design feasibility of the baseline optical design concept was established for the wide field/planetary camera (WF/PC) and will be used with the space telescope (ST) to obtain high angular resolution astronomical information over a wide field. The design concept employs internal optics to relay the ST image to a CCD detector system. Optical design performance predictions, sensitivity and tolerance analyses, manufacturability of the optical components, and acceptance testing of the two mirror Cassegrain relays are discussed.

SNS Emittance Scanner, Increasing Sensitivity and Performance through Noise Mitigation ,Design, Implementation and Results

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pogge, J.

2006-11-20

The Spallation Neutron Source (SNS) accelerator systems will deliver a 1.0 GeV, 1.4 MW proton beam to a liquid mercury target for neutron scattering research. The SNS MEBT Emittance Harp consists of 16 X and 16 Y wires, located in close proximity to the RFQ, Source, and MEBT Choppers. Beam Studies for source and LINAC commissioning required an overall increase in sensitivity for halo monitoring and measurement, and at the same time several severe noise sources had to be effectively removed from the harp signals. This paper is an overview of the design approach and techniques used in increasing gainmore » and sensitivity while maintaining a large signal to noise ratio for the emittance scanner device. A brief discussion of the identification of the noise sources, the mechanism for transmission and pick up, how the signals were improved and a summary of results.« less

Optimal design of microtube recuperators for an indirect supercritical carbon dioxide recompression closed Brayton cycle

DOE PAGES

Jiang, Yuan; Liese, Eric; Zitney, Stephen E.; ...

2018-02-25

This paper presents a baseline design and optimization approach developed in Aspen Custom Modeler (ACM) for microtube shell-and-tube exchangers (MSTEs) used for high- and low-temperature recuperation in a 10 MWe indirect supercritical carbon dioxide (sCO 2) recompression closed Brayton cycle (RCBC). The MSTE-type recuperators are designed using one-dimensional models with thermal-hydraulic correlations appropriate for sCO 2 and properties models that capture considerable nonlinear changes in CO 2 properties near the critical and pseudo-critical points. Using the successive quadratic programming (SQP) algorithm in ACM, optimal recuperator designs are obtained for either custom or industry-standard microtubes considering constraints based on current advancedmore » manufacturing techniques. The three decision variables are the number of tubes, tube pitch-to-diameter ratio, and tube diameter. Five different objective functions based on different key design measures are considered: minimization of total heat transfer area, heat exchanger volume, metal weight, thermal residence time, and maximization of compactness. Sensitivities studies indicate the constraint on the maximum number of tubes per shell does affect the number of parallel heat exchanger trains but not the tube selection, total number of tubes, tube length and other key design measures in the final optimal design when considering industry-standard tubes. In this study, the optimally designed high- and low-temperature recuperators have 47,000 3/32 inch tubes and 63,000 1/16 inch tubes, respectively. In addition, sensitivities to the design temperature approach and maximum allowable pressure drop are studied, since these specifications significantly impact the optimal design of the recuperators as well as the thermal efficiency and the economic performance of the entire sCO 2 Brayton cycle.« less

Optimal design of microtube recuperators for an indirect supercritical carbon dioxide recompression closed Brayton cycle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, Yuan; Liese, Eric; Zitney, Stephen E.

This paper presents a baseline design and optimization approach developed in Aspen Custom Modeler (ACM) for microtube shell-and-tube exchangers (MSTEs) used for high- and low-temperature recuperation in a 10 MWe indirect supercritical carbon dioxide (sCO 2) recompression closed Brayton cycle (RCBC). The MSTE-type recuperators are designed using one-dimensional models with thermal-hydraulic correlations appropriate for sCO 2 and properties models that capture considerable nonlinear changes in CO 2 properties near the critical and pseudo-critical points. Using the successive quadratic programming (SQP) algorithm in ACM, optimal recuperator designs are obtained for either custom or industry-standard microtubes considering constraints based on current advancedmore » manufacturing techniques. The three decision variables are the number of tubes, tube pitch-to-diameter ratio, and tube diameter. Five different objective functions based on different key design measures are considered: minimization of total heat transfer area, heat exchanger volume, metal weight, thermal residence time, and maximization of compactness. Sensitivities studies indicate the constraint on the maximum number of tubes per shell does affect the number of parallel heat exchanger trains but not the tube selection, total number of tubes, tube length and other key design measures in the final optimal design when considering industry-standard tubes. In this study, the optimally designed high- and low-temperature recuperators have 47,000 3/32 inch tubes and 63,000 1/16 inch tubes, respectively. In addition, sensitivities to the design temperature approach and maximum allowable pressure drop are studied, since these specifications significantly impact the optimal design of the recuperators as well as the thermal efficiency and the economic performance of the entire sCO 2 Brayton cycle.« less

Demographic factors associated with moral sensitivity among nursing students.

PubMed

Tuvesson, Hanna; Lützén, Kim

2017-11-01

Today's healthcare environment is often characterized by an ethically demanding work situation, and nursing students need to prepare to meet ethical challenges in their future role. Moral sensitivity is an important aspect of the ethical decision-making process, but little is known regarding nursing students' moral sensitivity and its possible development during nursing education. The aims of this study were to investigate moral sensitivity among nursing students, differences in moral sensitivity according to sample sub-group, and the relation between demographic characteristics of nursing students and moral sensitivity. A convenience sample of 299 nursing students from one university completed a questionnaire comprising questions about demographic information and the revised Moral Sensitivity Questionnaire. With the use of SPSS, non-parametric statistics, including logistic regression models, were used to investigate the relationship between demographic characteristics and moral sensitivity. Ethical considerations: The study followed the regulations according to the Swedish Ethical Review Act and was reviewed by the Ethics Committee of South-East Sweden. The findings showed that mean scores of nursing students' moral sensitivity were found in the middle to upper segment of the rating scale. Multivariate analysis showed that gender (odds ratio = 3.32), age (odds ratio = 2.09; 1.73), and parental status (odds ratio = 0.31) were of relevance to nursing students' moral sensitivity. Academic year was found to be unrelated to moral sensitivity. These demographic aspects should be considered when designing ethics education for nursing students. Future studies should continue to investigate moral sensitivity in nursing students, such as if and how various pedagogical strategies in ethics may contribute to moral sensitivity in nursing students.

Polymer/silica hybrid waveguide temperature sensor based on asymmetric Mach-Zehnder interferometer

NASA Astrophysics Data System (ADS)

Niu, Donghai; Wang, Xibin; Sun, Shiqi; Jiang, Minghui; Xu, Qiang; Wang, Fei; Wu, Yuanda; Zhang, Daming

2018-04-01

A highly sensitive waveguide temperature sensor based on asymmetric Mach-Zehnder interferometer was designed and experimentally demonstrated. The interferometer is based on the polymer/silica hybrid waveguide structure, and Norland Optical Adhesive 73 (NOA 73) was employed as the waveguide core to enhance the temperature sensitivity. The influence of the different length differences between the two interferometer arms on the sensitivity of the sensor was systemically studied. It is shown that the maximum temperature sensitivity of -431 pm °C-1 can be obtained in the range of 25 °C-75 °C, while the length difference is 92 μm. Moreover, the temperature sensitivity contributions from different core materials were also investigated experimentally. It is shown that the waveguide material and microstructure of the device have significant influences on the sensitivity of the waveguide temperature sensor.

Integrating aerodynamics and structures in the minimum weight design of a supersonic transport wing

NASA Technical Reports Server (NTRS)

Barthelemy, Jean-Francois M.; Wrenn, Gregory A.; Dovi, Augustine R.; Coen, Peter G.; Hall, Laura E.

1992-01-01

An approach is presented for determining the minimum weight design of aircraft wing models which takes into consideration aerodynamics-structure coupling when calculating both zeroth order information needed for analysis and first order information needed for optimization. When performing sensitivity analysis, coupling is accounted for by using a generalized sensitivity formulation. The results presented show that the aeroelastic effects are calculated properly and noticeably reduce constraint approximation errors. However, for the particular example selected, the error introduced by ignoring aeroelastic effects are not sufficient to significantly affect the convergence of the optimization process. Trade studies are reported that consider different structural materials, internal spar layouts, and panel buckling lengths. For the formulation, model and materials used in this study, an advanced aluminum material produced the lightest design while satisfying the problem constraints. Also, shorter panel buckling lengths resulted in lower weights by permitting smaller panel thicknesses and generally, by unloading the wing skins and loading the spar caps. Finally, straight spars required slightly lower wing weights than angled spars.

Micro-jitter attenuation of spaceborne cooler by using a blade-type hyperelastic shape memory alloy passive isolator

NASA Astrophysics Data System (ADS)

Kwon, Seong-Cheol; Jeon, Young-Hyeon; Oh, Hyun-Ung

2017-10-01

In this study, the primary design objective is to develop a passive isolator that can guarantee structural safety of the cooler assembly in a launch vibration environment without a launch locking mechanism, while effectively isolating the cooler-induced micro-jitter during the on-orbit operation of the cooler. To achieve the design objective, we focused on the utilization of characteristics of the hyperelastic shape memory effects. The major advantage of the isolator is that the micro-jitter isolation performance is much less sensitive to the aligned position of the isolator in comparison with the conventional isolator. Moreover, implementation of an additional 0g compensation device during a satellite level on-ground test, such as a jitter measurement test, is not required. In this study, the basic characteristics of the isolator were measured using the torque test and free vibration test. The micro-jitter attenuation capability and position sensitivity of the proposed isolator design were validated by the micro-jitter measurement test.

Involving consumers in product design through collaboration: the case of online role-playing games.

PubMed

Yeh, Shu-Yu

2010-12-01

The release of software attributes to users by software designers for the creation of user-designed forms is regarded as a producer-consumer collaboration, leading consumers to expend significant effort on a specific product. This article identifies such software/product attributes within online role-playing games and then explores how consumers' prior experience affects the evaluation of such attributes. In this article, product attributes comprise customized, content, and interactive externality-sensitive and complementary externality-sensitive attributes, with the value of each attribute being greater for experts than for novices. In Study 1, data were collected and analyzed for the purpose of identifying such features in online role-playing games. The results can also be generalized to convergent products, such as TV games that have been redesigned as online games or mobile games found in Study 2. For the introduction of a convergent product to be successful, our research suggests that the potential market-segment focus should be on knowledgeable consumers who accept such products more readily.

Inviscid/Boundary-Layer Aeroheating Approach for Integrated Vehicle Design

NASA Technical Reports Server (NTRS)

Lee, Esther; Wurster, Kathryn E.

2017-01-01

A typical entry vehicle design depends on the synthesis of many essential subsystems, including thermal protection system (TPS), structures, payload, avionics, and propulsion, among others. The ability to incorporate aerothermodynamic considerations and TPS design into the early design phase is crucial, as both are closely coupled to the vehicle's aerodynamics, shape and mass. In the preliminary design stage, reasonably accurate results with rapid turn-representative entry envelope was explored. Initial results suggest that for Mach numbers ranging from 9-20, a few inviscid solutions could reasonably sup- port surface heating predictions at Mach numbers variation of +/-2, altitudes variation of +/-10 to 20 kft, and angle-of-attack variation of +/- 5. Agreement with Navier-Stokes solutions was generally found to be within 10-15% for Mach number and altitude, and 20% for angle of attack. A smaller angle-of-attack increment than the 5 deg around times for parametric studies and quickly evolving configurations are necessary to steer design decisions. This investigation considers the use of an unstructured 3D inviscid code in conjunction with an integral boundary-layer method; the former providing the flow field solution and the latter the surface heating. Sensitivity studies for Mach number, angle of attack, and altitude, examine the feasibility of using this approach to populate a representative entry flight envelope based on a limited set of inviscid solutions. Each inviscid solution is used to generate surface heating over the nearby trajectory space. A subset of a considered in this study is recommended. Results of the angle-of-attack sensitivity studies show that smaller increments may be needed for better heating predictions. The approach is well suited for application to conceptual multidisciplinary design and analysis studies where transient aeroheating environments are critical for vehicle TPS and thermal design. Concurrent prediction of aeroheating environments, coupled with the use of unstructured methods, is considered enabling for TPS material selection and design in conceptual studies where vehicle mission, shape, and entry strategies evolve rapidly.

Three-Dimensional Finite Element Ablative Thermal Response and Thermostructural Design of Thermal Protection Systems

NASA Technical Reports Server (NTRS)

Dec, John A.; Braun, Robert D.

2011-01-01

A finite element ablation and thermal response program is presented for simulation of three-dimensional transient thermostructural analysis. The three-dimensional governing differential equations and finite element formulation are summarized. A novel probabilistic design methodology for thermal protection systems is presented. The design methodology is an eight step process beginning with a parameter sensitivity study and is followed by a deterministic analysis whereby an optimum design can determined. The design process concludes with a Monte Carlo simulation where the probabilities of exceeding design specifications are estimated. The design methodology is demonstrated by applying the methodology to the carbon phenolic compression pads of the Crew Exploration Vehicle. The maximum allowed values of bondline temperature and tensile stress are used as the design specifications in this study.

Computation of Sensitivity Derivatives of Navier-Stokes Equations using Complex Variables

NASA Technical Reports Server (NTRS)

Vatsa, Veer N.

2004-01-01

Accurate computation of sensitivity derivatives is becoming an important item in Computational Fluid Dynamics (CFD) because of recent emphasis on using nonlinear CFD methods in aerodynamic design, optimization, stability and control related problems. Several techniques are available to compute gradients or sensitivity derivatives of desired flow quantities or cost functions with respect to selected independent (design) variables. Perhaps the most common and oldest method is to use straightforward finite-differences for the evaluation of sensitivity derivatives. Although very simple, this method is prone to errors associated with choice of step sizes and can be cumbersome for geometric variables. The cost per design variable for computing sensitivity derivatives with central differencing is at least equal to the cost of three full analyses, but is usually much larger in practice due to difficulty in choosing step sizes. Another approach gaining popularity is the use of Automatic Differentiation software (such as ADIFOR) to process the source code, which in turn can be used to evaluate the sensitivity derivatives of preselected functions with respect to chosen design variables. In principle, this approach is also very straightforward and quite promising. The main drawback is the large memory requirement because memory use increases linearly with the number of design variables. ADIFOR software can also be cumber-some for large CFD codes and has not yet reached a full maturity level for production codes, especially in parallel computing environments.

Aerothermodynamic Design Sensitivities for a Reacting Gas Flow Solver on an Unstructured Mesh Using a Discrete Adjoint Formulation

NASA Astrophysics Data System (ADS)

Thompson, Kyle Bonner

An algorithm is described to efficiently compute aerothermodynamic design sensitivities using a decoupled variable set. In a conventional approach to computing design sensitivities for reacting flows, the species continuity equations are fully coupled to the conservation laws for momentum and energy. In this algorithm, the species continuity equations are solved separately from the mixture continuity, momentum, and total energy equations. This decoupling simplifies the implicit system, so that the flow solver can be made significantly more efficient, with very little penalty on overall scheme robustness. Most importantly, the computational cost of the point implicit relaxation is shown to scale linearly with the number of species for the decoupled system, whereas the fully coupled approach scales quadratically. Also, the decoupled method significantly reduces the cost in wall time and memory in comparison to the fully coupled approach. This decoupled approach for computing design sensitivities with the adjoint system is demonstrated for inviscid flow in chemical non-equilibrium around a re-entry vehicle with a retro-firing annular nozzle. The sensitivities of the surface temperature and mass flow rate through the nozzle plenum are computed with respect to plenum conditions and verified against sensitivities computed using a complex-variable finite-difference approach. The decoupled scheme significantly reduces the computational time and memory required to complete the optimization, making this an attractive method for high-fidelity design of hypersonic vehicles.

Grid-Optimization Program for Photovoltaic Cells

NASA Technical Reports Server (NTRS)

Daniel, R. E.; Lee, T. S.

1986-01-01

CELLOPT program developed to assist in designing grid pattern of current-conducting material on photovoltaic cell. Analyzes parasitic resistance losses and shadow loss associated with metallized grid pattern on both round and rectangular solar cells. Though performs sensitivity studies, used primarily to optimize grid design in terms of bus bar and grid lines by minimizing power loss. CELLOPT written in APL.

Differences in Meta-Aesthetic Consciousness in Students Taking Fine Arts, Design and Academy Education

ERIC Educational Resources Information Center

Tataroglu, Eylem

2016-01-01

Meta-aesthetics is the aesthetic field relating to the images of products where the conversion value, separate from the product's function, takes part directly in its value. Meta-aesthetics is among the subjects that today's art and design world must address more sensitively. This study was based on a 2009 dissertation measuring university…

Optimization Under Uncertainty for Electronics Cooling Design

NASA Astrophysics Data System (ADS)

Bodla, Karthik K.; Murthy, Jayathi Y.; Garimella, Suresh V.

Optimization under uncertainty is a powerful methodology used in design and optimization to produce robust, reliable designs. Such an optimization methodology, employed when the input quantities of interest are uncertain, produces output uncertainties, helping the designer choose input parameters that would result in satisfactory thermal solutions. Apart from providing basic statistical information such as mean and standard deviation in the output quantities, auxiliary data from an uncertainty based optimization, such as local and global sensitivities, help the designer decide the input parameter(s) to which the output quantity of interest is most sensitive. This helps the design of experiments based on the most sensitive input parameter(s). A further crucial output of such a methodology is the solution to the inverse problem - finding the allowable uncertainty range in the input parameter(s), given an acceptable uncertainty range in the output quantity of interest...

Design, data, and theory regarding a digital hand inclinometer: a portable device for studying slant perception.

PubMed

Li, Zhi; Durgin, Frank H

2011-06-01

Palm boards are often used as a nonverbal measure in human slant perception studies. It was recently found that palm boards are biased and relatively insensitive measures, and that an unrestricted hand gesture provides a more sensitive response (Durgin, Hajnal, Li, Tonge, & Stigliani, Acta Psychologica, 134, 182-197, 2010a). In this article, we describe an original design for a portable lightweight digital device for measuring hand orientation. This device is microcontroller-based and uses a micro inclinometer chip as its inclination sensor. The parts are fairly inexpensive. This device, used to measure hand orientation, provides a sensitive nonverbal method for studying slant perception, which can be used in both indoor and outdoor environments. We present data comparing the use of a free hand to palm-board and verbal measures for surfaces within reach and explain how to interpret free-hand measures for outdoor hills.

Diagnostic utility of patient history and physical examination data to detect spondylolysis and spondylolisthesis in athletes with low back pain: A systematic review.

PubMed

Grødahl, Linn Helen J; Fawcett, Louise; Nazareth, Madeleine; Smith, Richard; Spencer, Simon; Heneghan, Nicola; Rushton, Alison

2016-08-01

In adolescent athletes, low back pain has a 1-year prevalence of 57% and causes include spondylolysis and spondylolisthesis. An accurate diagnosis enables healing, prevention of progression and return to sport. To evaluate the diagnostic utility of patient history and physical examination data to identify spondylolysis and/or spondylolisthesis in athletes. Systematic review was undertaken according to published guidelines, and reported in line with PRISMA. Key databases were searched up to 13/11/15. athletic population with LBP, patient history and/or physical examination accuracy data for spondylolysis and/or spondylolisthesis, any study design including raw data. Two reviewers independently assessed risk of bias (ROB) using QUADAS-2. A data extraction sheet was pre-designed. Pooling of data and investigation for heterogeneity enabled a qualitative synthesis of data across studies. Of the eight included studies, two were assessed as low ROB, one of which also had no concerns regarding applicability. Age (<20 years) demonstrated 81% sensitivity and 44% specificity and gender (male) 73% sensitivity and 57% specificity for spondylolysis. Difficulty falling asleep, waking up because of pain, pain worse with sitting and walking all have sensitivity >75% for spondylolisthesis. Step-deformity palpation demonstrated 60-88% sensitivity and 87-100% specificity for spondylolisthesis. The one-legged hyperextension test was not supported for spondylolysis (sensitivity 50-73%, specificity 0-87%). No recommendations can be made utilising patient history data. Based on one low ROB study, step deformity palpation may be useful in diagnosing spondylolisthesis. No physical tests demonstrated diagnostic utility for spondylolysis. Further research is required. Copyright © 2016 Elsevier Ltd. All rights reserved.

Examples of sex/gender sensitivity in epidemiological research: results of an evaluation of original articles published in JECH 2006-2014.

PubMed

Jahn, Ingeborg; Börnhorst, Claudia; Günther, Frauke; Brand, Tilman

2017-02-15

During the last decades, sex and gender biases have been identified in various areas of biomedical and public health research, leading to compromised validity of research findings. As a response, methodological requirements were developed but these are rarely translated into research practice. The aim of this study is to provide good practice examples of sex/gender sensitive health research. We conducted a systematic search of research articles published in JECH between 2006 and 2014. An instrument was constructed to evaluate sex/gender sensitivity in four stages of the research process (background, study design, statistical analysis, discussion). In total, 37 articles covering diverse topics were included. Thereof, 22 were evaluated as good practice example in at least one stage; two articles achieved highest ratings across all stages. Good examples of the background referred to available knowledge on sex/gender differences and sex/gender informed theoretical frameworks. Related to the study design, good examples calculated sample sizes to be able to detect sex/gender differences, selected sex/gender sensitive outcome/exposure indicators, or chose different cut-off values for male and female participants. Good examples of statistical analyses used interaction terms with sex/gender or different shapes of the estimated relationship for men and women. Examples of good discussions interpreted their findings related to social and biological explanatory models or questioned the statistical methods used to detect sex/gender differences. The identified good practice examples may inspire researchers to critically reflect on the relevance of sex/gender issues of their studies and help them to translate methodological recommendations of sex/gender sensitivity into research practice.

Early morning urine collection to improve urinary lateral flow LAM assay sensitivity in hospitalised patients with HIV-TB co-infection.

PubMed

Gina, Phindile; Randall, Philippa J; Muchinga, Tapuwa E; Pooran, Anil; Meldau, Richard; Peter, Jonny G; Dheda, Keertan

2017-05-12

Urine LAM testing has been approved by the WHO for use in hospitalised patients with advanced immunosuppression. However, sensitivity remains suboptimal. We therefore examined the incremental diagnostic sensitivity of early morning urine (EMU) versus random urine sampling using the Determine® lateral flow lipoarabinomannan assay (LF-LAM) in HIV-TB co-infected patients. Consenting HIV-infected inpatients, screened as part of a larger prospective randomized controlled trial, that were treated for TB, and could donate matched random and EMU samples were included. Thus paired sample were collected from the same patient, LF-LAM was graded using the pre-January 2014, with grade 1 and 2 manufacturer-designated cut-points (the latter designated grade 1 after January 2014). Single sputum Xpert-MTB/RIF and/or TB culture positivity served as the reference standard (definite TB). Those treated for TB but not meeting this standard were designated probable TB. 123 HIV-infected patients commenced anti-TB treatment and provided matched random and EMU samples. 33% (41/123) and 67% (82/123) had definite and probable TB, respectively. Amongst those with definite TB LF-LAM sensitivity (95%CI), using the grade 2 cut-point, increased from 12% (5-24; 5/43) to 39% (26-54; 16/41) with random versus EMU, respectively (p = 0.005). Similarly, amongst probable TB, LF-LAM sensitivity increased from 10% (5-17; 8/83) to 24% (16-34; 20/82) (p = 0.001). LF-LAM specificity was not determined. This proof of concept study indicates that EMU could improve the sensitivity of LF-LAM in hospitalised TB-HIV co-infected patients. These data have implications for clinical practice.

Nested PCR Assay for Eight Pathogens: A Rapid Tool for Diagnosis of Bacterial Meningitis.

PubMed

Bhagchandani, Sharda P; Kubade, Sushant; Nikhare, Priyanka P; Manke, Sonali; Chandak, Nitin H; Kabra, Dinesh; Baheti, Neeraj N; Agrawal, Vijay S; Sarda, Pankaj; Mahajan, Parikshit; Ganjre, Ashish; Purohit, Hemant J; Singh, Lokendra; Taori, Girdhar M; Daginawala, Hatim F; Kashyap, Rajpal S

2016-02-01

Bacterial meningitis is a dreadful infectious disease with a high mortality and morbidity if remained undiagnosed. Traditional diagnostic methods for bacterial meningitis pose a challenge in accurate identification of pathogen, making prognosis difficult. The present study is therefore aimed to design and evaluate a specific and sensitive nested 16S rDNA genus-based polymerase chain reaction (PCR) assay using clinical cerebrospinal fluid (CSF) for rapid diagnosis of eight pathogens causing the disease. The present work was dedicated to development of an in-house genus specific 16S rDNA nested PCR covering pathogens of eight genera responsible for causing bacterial meningitis using newly designed as well as literature based primers for respective genus. A total 150 suspected meningitis CSF obtained from the patients admitted to Central India Institute of Medical Sciences (CIIMS), India during the period from August 2011 to May 2014, were used to evaluate clinical sensitivity and clinical specificity of optimized PCR assays. The analytical sensitivity and specificity of our newly designed genus-specific 16S rDNA PCR were found to be ≥92%. With such a high sensitivity and specificity, our in-house nested PCR was able to give 100% sensitivity in clinically confirmed positive cases and 100% specificity in clinically confirmed negative cases indicating its applicability in clinical diagnosis. Our in-house nested PCR system therefore can diagnose the accurate pathogen causing bacterial meningitis and therefore be useful in selecting a specific treatment line to minimize morbidity. Results are obtained within 24 h and high sensitivity makes this nested PCR assay a rapid and accurate diagnostic tool compared to traditional culture-based methods.

Sensitivity analysis of bi-layered ceramic dental restorations.

PubMed

Zhang, Zhongpu; Zhou, Shiwei; Li, Qing; Li, Wei; Swain, Michael V

2012-02-01

The reliability and longevity of ceramic prostheses have become a major concern. The existing studies have focused on some critical issues from clinical perspectives, but more researches are needed to address fundamental sciences and fabrication issues to ensure the longevity and durability of ceramic prostheses. The aim of this paper was to explore how "sensitive" the thermal and mechanical responses, in terms of changes in temperature and thermal residual stress of the bi-layered ceramic systems and crown models will be with respect to the perturbation of the design variables chosen (e.g. layer thickness and heat transfer coefficient) in a quantitative way. In this study, three bi-layered ceramic models with different geometries are considered: (i) a simple bi-layered plate, (ii) a simple bi-layer triangle, and (iii) an axisymmetric bi-layered crown. The layer thickness and convective heat transfer coefficient (or cooling rate) seem to be more sensitive for the porcelain fused on zirconia substrate models. The resultant sensitivities indicate a critical importance of the heat transfer coefficient and thickness ratio of core to veneer on the temperature distributions and residual stresses in each model. The findings provide a quantitative basis for assessing the effects of fabrication uncertainties and optimizing the design of ceramic prostheses. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Solid state SPS microwave generation and transmission study. Volume 2, phase 2: Appendices

NASA Technical Reports Server (NTRS)

Maynard, O. E.

1980-01-01

The solid state sandwich concept for SPS was further defined. The design effort concentrated on the spacetenna, but did include some system analysis for parametric comparison reasons. Basic solid state microwave devices were defined and modeled. An initial conceptual subsystems and system design was performed as well as sidelobe control and system selection. The selected system concept and parametric solid state microwave power transmission system data were assessed relevant to the SPS concept. Although device efficiency was not a goal, the sensitivities to design of this efficiency were parametrically treated. Sidelobe control consisted of various single step tapers, multistep tapers and Gaussian tapers. A hybrid concept using tubes and solid state was evaluated. Thermal analyses are included with emphasis on sensitivities to waste heat radiator form factor, emissivity, absorptivity, amplifier efficiency, material and junction temperature.

Natural environment design criteria for the Space Station definition and preliminary design

NASA Astrophysics Data System (ADS)

Vaughan, W. W.; Green, C. E.

1985-03-01

The natural environment design criteria for the Space Station Program (SSP) definition and preliminary design are presented. Information on the atmospheric, dynamic and thermodynamic environments, meteoroids, radiation, magnetic fields, physical constants, etc. is provided with the intension of enabling all groups involved in the definition and preliminary design studies to proceed with a common and consistent set of natural environment criteria requirements. The space station program elements (SSPE) shall be designed with no operational sensitivity to natural environment conditions during assembly, checkout, stowage, launch, and orbital operations to the maximum degree practical.

Natural environment design criteria for the Space Station definition and preliminary design

NASA Technical Reports Server (NTRS)

Vaughan, W. W.; Green, C. E.

1985-01-01

The natural environment design criteria for the Space Station Program (SSP) definition and preliminary design are presented. Information on the atmospheric, dynamic and thermodynamic environments, meteoroids, radiation, magnetic fields, physical constants, etc. is provided with the intension of enabling all groups involved in the definition and preliminary design studies to proceed with a common and consistent set of natural environment criteria requirements. The space station program elements (SSPE) shall be designed with no operational sensitivity to natural environment conditions during assembly, checkout, stowage, launch, and orbital operations to the maximum degree practical.

Technical and economic evaluation of advanced air cargo system concepts

NASA Technical Reports Server (NTRS)

Whitehead, A. H., Jr.

1977-01-01

The paper reviews NASA air cargo market studies, reports on NASA and NASA-sponsored studies of advanced freighter concepts, and identifies the opportunities for the application of advanced technology. The air cargo market is studied to evaluate the timing for, and the potential market response to, advanced technology aircraft. The degree of elasticity in future air freight markets is also being investigated, since the demand for a new aircraft is most favorable in a price-sensitive environment. Aircraft design studies are considered with attention to mission and design requirements, incorporation of advanced technologies in transport aircraft, new cargo aircraft concepts, advanced freighter evaluation, and civil-military design commonality.

Frequency dependence of sensitivities in second-order RC active filters

NASA Astrophysics Data System (ADS)

Kunieda, T.; Hiramatsu, Y.; Fukui, A.

1980-02-01

This paper presents that gain and phase sensitivities to some element in biquadratic filters approximately constitute a circle on the complex sensitivity plane, provided that the quality factor Q of the circuit is appreciably larger than unity. Moreover, the group delay sensitivity is represented by the imaginary part of a cardioid. Using these results, bounds of maximum values of gain, phase, and group delay sensitivities are obtained. Further, it is proved that the maximum values of these sensitivities can be simultaneously minimized by minimizing the absolute value of the transfer function sensitivity at the center frequency provided that w(0)-sensitivities are constant and do not contain design parameters. Next, a statistical variability measure for the optimal-filter design is proposed. Finally, the relation between some variability measures proposed to the present time is made clear.

A Monte Carlo study of different detector geometries for HAWC

NASA Astrophysics Data System (ADS)

Gebauer, Iris

Compared to other parts of astronomy the study of the universe at energies above 100GeV is a relatively new field. Pointed instruments presently achieve the highest sensitivities. They have detected gamma-rays from at least 10 sources, but they are only able to monitor a relatively small fraction of the sky. The detection of exciting phenomena such as Gamma-ray Bursts (GRBs) requires a highly sensitive detector capable of continuously monitoring the entire overhead sky. Such an instrument could make an unbiased study of the entire field of view. With sufficient sensitivity it could detect short transients (~ 15 minutes) and study the time structure of Active galactic nuclei (AGN) flares at energies unattainable to space-based instruments. This thesis describes the design and performance of the next generation water Cherenkov detector HAWC (High Altitude Water Cherenkov). Focussing on the performance in background-rejection and sensitivity to point sources, two possible detector geometries, different in the way the photomultipliers (PMTs) are separated from each other, are compared.

Design of butterfly type organic dye sensitizers with double electron donors: The first principle study

NASA Astrophysics Data System (ADS)

Yang, Zhenqing; Shao, Di; Li, Juan; Tang, Lian; Shao, Changjin

2018-05-01

In this work, we designed a series of butterfly type organic dyes, named ME07-ME13 by introducing such as triphenylamine, phenothiazine, coumarin groups etc. as electron donors and further investigated their absorption spectra using density functional theory (DFT) and time-dependent DFT (TDDFT). All designed dyes cover the entire visible absorption spectrum from 300 to 800 nm. It's fascinating that ME13 molecule has two absorption peak and the molar coefficient of two absorption peaks are above 4.645 × 104 M-1·cm-1. The light absorption area of ME13 exhibits an increment of 16.5-19.1% compared to ME07-ME12. Furthermore, we performed a detailed analysis on their geometrical and electronic properties, including molecular structures, energy levels, light harvesting efficiency (LHE), driving force (ΔGinject), regeneration (ΔGregen),electron dipole moments (μnormal), intermolecular electron transfer and dye/(TiO2)38 system electron transitions. The results of calculation reveal that double coumarin donors in ME13 are promising functional groups for butterfly type organic dye sensitizers. It is expected that the design of double donors can provide a new strategy and guidance for the investigation in high efficiency dye-sensitized devices.

Design and fabrication of a differential scanning nanocalorimeter

NASA Astrophysics Data System (ADS)

Zuo, Lei; Chen, Xiaoming; Yu, Shifeng; Lu, Ming

2017-02-01

This paper describes the design, fabrication, and characterization of a differential scanning nanocalorimeter that significantly reduces the sample volume to microliters and can potentially improve the temperature sensitivity to 10 µK. The nanocalorimeter consists of a polymeric freestanding membrane, four high-sensitive low-noise thermistors based on silicon carbide (SiC), and a platinum heater and temperature sensor. With the integrated heater and sensors, temperature scanning and power compensation can be achieved for calorimetric measurement. Temperature sensing SiC film was prepared by using sintered SiC target and DC magnetron sputtering under different gas pressures and sputtering power. The SiC sensing material is characterized through the measurement of current-voltage curves and noise levels. The thermal performance of a fabricated nanocalorimeter is studied in simulation and experiment. The experiment results show the device has excellent thermal isolation to hold thermal energy. The noise test together with the simulation show the device is promising for micro 10 µK temperature sensitivity and nanowatt resolution which will lead to low-volume ultra-sensitive nanocalorimetry for biological processes, such as protein folding and ligand binding.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Karaulanov, Todor; Savukov, Igor; Kim, Young Jin

We constructed a spin-exchange relaxation-free (SERF) magnetometer with a small angle between the pump and probe beams facilitating a multi-channel design with a flat pancake cell. This configuration provides almost complete overlap of the beams in the cell, and prevents the pump beam from entering the probe detection channel. By coupling the lasers in multi-mode fibers, without an optical isolator or field modulation, we demonstrate a sensitivity of 10 fTmore » $$/\\sqrt{\\text{Hz}}$$ for frequencies between 10 Hz and 100 Hz. In addition to the experimental study of sensitivity, we present a theoretical analysis of SERF magnetometer response to magnetic fields for small-angle and parallel-beam configurations, and show that at optimal DC offset fields the magnetometer response is comparable to that in the orthogonal-beam configuration. Based on the analysis, we also derive fundamental and probe-limited sensitivities for the arbitrary non-orthogonal geometry. The expected practical and fundamental sensitivities are of the same order as those in the orthogonal geometry. As a result, we anticipate that our design will be useful for magnetoencephalography (MEG) and magnetocardiography (MCG) applications.« less

Multiobjective sampling design for parameter estimation and model discrimination in groundwater solute transport

USGS Publications Warehouse

Knopman, Debra S.; Voss, Clifford I.

1989-01-01

Sampling design for site characterization studies of solute transport in porous media is formulated as a multiobjective problem. Optimal design of a sampling network is a sequential process in which the next phase of sampling is designed on the basis of all available physical knowledge of the system. Three objectives are considered: model discrimination, parameter estimation, and cost minimization. For the first two objectives, physically based measures of the value of information obtained from a set of observations are specified. In model discrimination, value of information of an observation point is measured in terms of the difference in solute concentration predicted by hypothesized models of transport. Points of greatest difference in predictions can contribute the most information to the discriminatory power of a sampling design. Sensitivity of solute concentration to a change in a parameter contributes information on the relative variance of a parameter estimate. Inclusion of points in a sampling design with high sensitivities to parameters tends to reduce variance in parameter estimates. Cost minimization accounts for both the capital cost of well installation and the operating costs of collection and analysis of field samples. Sensitivities, discrimination information, and well installation and sampling costs are used to form coefficients in the multiobjective problem in which the decision variables are binary (zero/one), each corresponding to the selection of an observation point in time and space. The solution to the multiobjective problem is a noninferior set of designs. To gain insight into effective design strategies, a one-dimensional solute transport problem is hypothesized. Then, an approximation of the noninferior set is found by enumerating 120 designs and evaluating objective functions for each of the designs. Trade-offs between pairs of objectives are demonstrated among the models. The value of an objective function for a given design is shown to correspond to the ability of a design to actually meet an objective.

Poisson and negative binomial item count techniques for surveys with sensitive question.

PubMed

Tian, Guo-Liang; Tang, Man-Lai; Wu, Qin; Liu, Yin

2017-04-01

Although the item count technique is useful in surveys with sensitive questions, privacy of those respondents who possess the sensitive characteristic of interest may not be well protected due to a defect in its original design. In this article, we propose two new survey designs (namely the Poisson item count technique and negative binomial item count technique) which replace several independent Bernoulli random variables required by the original item count technique with a single Poisson or negative binomial random variable, respectively. The proposed models not only provide closed form variance estimate and confidence interval within [0, 1] for the sensitive proportion, but also simplify the survey design of the original item count technique. Most importantly, the new designs do not leak respondents' privacy. Empirical results show that the proposed techniques perform satisfactorily in the sense that it yields accurate parameter estimate and confidence interval.

The Effects of Carbohydrate, Unsaturated Fat, and Protein Intake on Measures of Insulin Sensitivity

PubMed Central

Gadgil, Meghana D.; Appel, Lawrence J.; Yeung, Edwina; Anderson, Cheryl A.M.; Sacks, Frank M.; Miller, Edgar R.

2013-01-01

OBJECTIVE Impaired insulin sensitivity increases the risk of cardiovascular disease. Although calorie restriction and weight loss increase insulin sensitivity, the effects of modifying macronutrient composition on insulin sensitivity are uncertain. The purpose of this study is to determine the effects on insulin sensitivity of a carbohydrate-rich diet (CARB; similar to the Dietary Approaches to Stop Hypertension [DASH] diet), a protein-rich diet (PROT; protein predominantly from plant sources), and an unsaturated fat–rich diet (UNSAT; predominantly monounsaturated). RESEARCH DESIGN AND METHODS This study was a randomized, controlled, three-period, crossover feeding study. The study participants were 164 individuals with prehypertension or stage 1 hypertension without diabetes. Diets were administered for 6 weeks each, with a washout period between diets of 2–4 weeks. Weight was held constant throughout the study. For our primary outcome, we calculated the quantitative insulin sensitivity check index (QUICKI) using the end-of-period fasting serum glucose and insulin. QUICKI is a validated measure of insulin sensitivity. The primary analyses used generalized estimating equations. RESULTS At baseline, mean (SD) BMI was 30.2 (6.1) kg/m2, and mean (SD) QUICKI was 0.35 (0.04). The UNSAT diet increased QUICKI by 0.005, more than the CARB diet (P = 0.04). PROT had no significant effect compared with CARB. CONCLUSIONS A diet that partially replaces carbohydrate with unsaturated fat may improve insulin sensitivity in a population at risk for cardiovascular disease. Given the well-recognized challenges of sustaining weight loss, our results suggest an alternative approach for improving insulin sensitivity. PMID:23223345

Configuration evaluation and criteria plan. Volume 1: System trades study and design methodology plan (preliminary). Space Transportation Main Engine (STME) configuration study

NASA Technical Reports Server (NTRS)

Bair, E. K.

1986-01-01

The System Trades Study and Design Methodology Plan is used to conduct trade studies to define the combination of Space Shuttle Main Engine features that will optimize candidate engine configurations. This is accomplished by using vehicle sensitivities and engine parametric data to establish engine chamber pressure and area ratio design points for candidate engine configurations. Engineering analyses are to be conducted to refine and optimize the candidate configurations at their design points. The optimized engine data and characteristics are then evaluated and compared against other candidates being considered. The Evaluation Criteria Plan is then used to compare and rank the optimized engine configurations on the basis of cost.

Numerical study on refractive index sensor based on hybrid-plasmonic mode

NASA Astrophysics Data System (ADS)

Yun, Jeong-Geun; Kim, Joonsoo; Lee, Kyookeun; Lee, Yohan; Lee, Byoungho

2017-04-01

We propose a highly sensitive hybrid-plasmonic sensor based on thin-gold nanoslit arrays. The transmission characteristics of gold nanoslit arrays are analyzed as changing the thickness of gold layer. The surface plasmon polariton mode excited on the sensing medium, which is sensitive to refractive index change of the sensing medium, is strengthened by reducing the thickness of the gold layer. A design rule is suggested that steeper dispersion curve of the surface plasmon polariton mode leads to higher sensitivity. For the dispersion engineering, hybrid-plasmonic structure, which consists of thin-gold nanoslit arrays, sensing region and high refractive index dielectric space is introduced. The proposed sensor structure with period of 700 nm shows the improved sensitivity up to 1080 nm/RIU (refractive index unit), and the surface sensitivity is extremely enhanced.

Structural synthesis: Precursor and catalyst

NASA Technical Reports Server (NTRS)

Schmit, L. A.

1984-01-01

More than twenty five years have elapsed since it was recognized that a rather general class of structural design optimization tasks could be properly posed as an inequality constrained minimization problem. It is suggested that, independent of primary discipline area, it will be useful to think about: (1) posing design problems in terms of an objective function and inequality constraints; (2) generating design oriented approximate analysis methods (giving special attention to behavior sensitivity analysis); (3) distinguishing between decisions that lead to an analysis model and those that lead to a design model; (4) finding ways to generate a sequence of approximate design optimization problems that capture the essential characteristics of the primary problem, while still having an explicit algebraic form that is matched to one or more of the established optimization algorithms; (5) examining the potential of optimum design sensitivity analysis to facilitate quantitative trade-off studies as well as participation in multilevel design activities. It should be kept in mind that multilevel methods are inherently well suited to a parallel mode of operation in computer terms or to a division of labor between task groups in organizational terms. Based on structural experience with multilevel methods general guidelines are suggested.

Stratospheric Airship Design Sensitivity

NASA Astrophysics Data System (ADS)

Smith, Ira Steve; Fortenberry, Michael; Noll, . James; Perry, William

2012-07-01

The concept of a stratospheric or high altitude powered platform has been around almost as long as stratospheric free balloons. Airships are defined as Lighter-Than-Air (LTA) vehicles with propulsion and steering systems. Over the past five (5) years there has been an increased interest by the U. S. Department of Defense as well as commercial enterprises in airships at all altitudes. One of these interests is in the area of stratospheric airships. Whereas DoD is primarily interested in things that look down, such platforms offer a platform for science applications, both downward and outward looking. Designing airships to operate in the stratosphere is very challenging due to the extreme high altitude environment. It is significantly different than low altitude airship designs such as observed in the familiar advertising or tourism airships or blimps. The stratospheric airship design is very dependent on the specific application and the particular requirements levied on the vehicle with mass and power limits. The design is a complex iterative process and is sensitive to many factors. In an effort to identify the key factors that have the greatest impacts on the design, a parametric analysis of a simplified airship design has been performed. The results of these studies will be presented.

Dimensions of Culturally Sensitive Factors in the Design and Development of Learning Objects

ERIC Educational Resources Information Center

Qi, Mei; Boyle, Tom

2010-01-01

Open educational resources (OERs) are designed to be globally reusable. Yet comparatively little attention has been given to the cultural issues. This paper addresses the issue of culturally sensitive factors that may influence the design of reusable learning objects. These influences are often subtle and hard to manage. The paper proposes a…

Design and performance evaluation of a new high energy parallel hole collimator for radioiodine planar imaging by gamma cameras: Monte Carlo simulation study.

PubMed

Moslemi, Vahid; Ashoor, Mansour

2017-05-01

In addition to the trade-off between resolution and sensitivity which is a common problem among all types of parallel hole collimators (PCs), obtained images by high energy PCs (HEPCs) suffer from hole-pattern artifact (HPA) due to further septa thickness. In this study, a new design on the collimator has been proposed to improve the trade-off between resolution and sensitivity and to eliminate the HPA. A novel PC, namely high energy extended PC (HEEPC), is proposed and is compared to HEPCs. In the new PC, trapezoidal denticles were added upon the septa in the detector side. The performance of the HEEPCs were evaluated and compared to that of HEPCs using a Monte Carlo-N-particle version5 (MCNP5) simulation. The point spread functions (PSF) of HEPCs and HEEPCs were obtained as well as the various parameters such as resolution, sensitivity, scattering, and penetration ratios, and the HPA of the collimators was assessed. Furthermore, a Picker phantom study was performed to examine the effects of the collimators on the quality of planar images. It was found that the HEEPC D with an identical resolution to that of HEPC C increased sensitivity by 34.7%, and it improved the trade-off between resolution and sensitivity as well as to eliminate the HPA. In the picker phantom study, the HEEPC D indicated the hot and cold lesions with the higher contrast, lower noise, and higher contrast to noise ratio (CNR). Since the HEEPCs modify the shaping of PSFs, they are able to improve the trade-off between the resolution and sensitivity; consequently, planar images can be achieved with higher contrast resolutions. Furthermore, because the HEEPC S reduce the HPA and produce images with a higher CNR, compared to HEPCs, the obtained images by HEEPCs have a higher quality, which can help physicians to provide better diagnosis.

Parametric design and analysis on the landing gear of a planet lander using the response surface method

NASA Astrophysics Data System (ADS)

Zheng, Guang; Nie, Hong; Luo, Min; Chen, Jinbao; Man, Jianfeng; Chen, Chuanzhi; Lee, Heow Pueh

2018-07-01

The purpose of this paper is to obtain the design parameter-landing response relation for designing the configuration of the landing gear in a planet lander quickly. To achieve this, parametric studies on the landing gear are carried out using the response surface method (RSM), based on a single landing gear landing model validated by experimental results. According to the design of experiment (DOE) results of the landing model, the RS (response surface)-functions of the three crucial landing responses are obtained, and the sensitivity analysis (SA) of the corresponding parameters is performed. Also, two multi-objective optimizations designs on the landing gear are carried out. The analysis results show that the RS (response surface)-model performs well for the landing response design process, with a minimum fitting accuracy of 98.99%. The most sensitive parameters for the three landing response are the design size of the buffers, struts friction and the diameter of the bending beam. Moreover, the good agreement between the simulated model and RS-model results are obtained in two optimized designs, which show that the RS-model coupled with the FE (finite element)-method is an efficient method to obtain the design configuration of the landing gear.

Thermal design and verification of an instrument cooling system for infrared detectors utilizing the Oxford Stirling cycle refrigerator

NASA Technical Reports Server (NTRS)

Werrett, Stephen; Seivold, Alfred L.

1990-01-01

A detailed nodal computer model was developed to thermally represent the hardware, and sensitivity studies were performed to evaluate design parameters and orbital environmental effects of an instrument cooling system for IR detectors. Thermal-vacuum testing showed excellent performance of the system and a correspondence with math model predictions to within 3 K. Results show cold stage temperature sensitivity to cold patch backload, outer stage external surface emittance degradation, and cold stage emittance degradation, respectively. The increase in backload on the cold patch over the mission lifetime is anticipated to be less than 3.0 watts, which translates to less than a 3-degree increase in detector temperatures.

Crevicular Fluid and Serum Concentrations of Progranulin and High Sensitivity CRP in Chronic Periodontitis and Type 2 Diabetes

PubMed Central

Priyanka, N.; Kumari, Minal; Kalra, Nitish; Arjun, P.; Naik, Savitha B.; Pradeep, A. R.

2013-01-01

Introduction. This study was designed to correlate the serum and gingival crevicular fluid (GCF) levels of progranulin (PGRN) and high sensitivity C-reactive protein (hs CRP) in chronic periodontitis and type 2 diabetes mellitus (DM). Design. PGRN and hs CRP levels were estimated in 3 groups: healthy, chronic periodontitis, and type 2 DM with chronic periodontitis. Results. The mean PGRN and hs CRP concentrations in serum and GCF were the highest for group 3 followed by group 2 and the least in group 1. Conclusion. PGRN and hs CRP may be biomarkers of the inflammatory response in type 2 DM and chronic periodontitis. PMID:24191130

Limited Qualities Evaluation of Longitudinal Flight Control Systems Designed Using Multiobjective Control Design Techniques (HAVE INFINITY II)

DTIC Science & Technology

1998-06-01

analytical phase of this research. Finally, the mixed H2/H-Infinity method optimally tradeoff the different benefits offered by the separate H2 and H...potential benefits of the multiobjective design techniques used. Due to the HAVE INFINITY I test results, AFIT made the decision to continue the...sensitivity and complimentary sensitivity weighting, and a mixed H2/H-Infinity design that compromised the benefits of both design techniques optimally. The

Design sensitivity analysis of boundary element substructures

NASA Technical Reports Server (NTRS)

Kane, James H.; Saigal, Sunil; Gallagher, Richard H.

1989-01-01

The ability to reduce or condense a three-dimensional model exactly, and then iterate on this reduced size model representing the parts of the design that are allowed to change in an optimization loop is discussed. The discussion presents the results obtained from an ongoing research effort to exploit the concept of substructuring within the structural shape optimization context using a Boundary Element Analysis (BEA) formulation. The first part contains a formulation for the exact condensation of portions of the overall boundary element model designated as substructures. The use of reduced boundary element models in shape optimization requires that structural sensitivity analysis can be performed. A reduced sensitivity analysis formulation is then presented that allows for the calculation of structural response sensitivities of both the substructured (reduced) and unsubstructured parts of the model. It is shown that this approach produces significant computational economy in the design sensitivity analysis and reanalysis process by facilitating the block triangular factorization and forward reduction and backward substitution of smaller matrices. The implementatior of this formulation is discussed and timings and accuracies of representative test cases presented.

Stressful Life Events, Anxiety Sensitivity, and Internalizing Symptoms in Adolescents

PubMed Central

McLaughlin, Katie A.; Hatzenbuehler, Mark L.

2010-01-01

Anxiety sensitivity represents a robust risk factor for the development of anxiety symptoms among both adolescents and adults. However, the development of anxiety sensitivity among adolescents remains inadequately understood. In this study, the authors examined the role of stressful life events as a risk factor for the development of elevated anxiety sensitivity. Anxiety sensitivity was then examined in a longitudinal design as a mechanism linking stressful life events to changes in anxiety symptoms. Stressful life events, anxiety sensitivity, and internalizing symptoms were assessed in a diverse community sample of adolescents (N = 1,065) at 3 time points spanning 7 months. The results indicated that stressful life events were longitudinally associated with increases in anxiety sensitivity and that certain types of stressful life events, specifically events related to health and events related to family discord, were differentially predictive of increases in anxiety sensitivity. Moreover, anxiety sensitivity mediated the longitudinal relation between stressful life events and anxiety symptoms. Evidence was also found for the predictive specificity of anxiety sensitivity to symptoms of anxiety but not depression. PMID:19685962

Stressful life events, anxiety sensitivity, and internalizing symptoms in adolescents.

PubMed

McLaughlin, Katie A; Hatzenbuehler, Mark L

2009-08-01

Anxiety sensitivity represents a robust risk factor for the development of anxiety symptoms among both adolescents and adults. However, the development of anxiety sensitivity among adolescents remains inadequately understood. In this study, the authors examined the role of stressful life events as a risk factor for the development of elevated anxiety sensitivity. Anxiety sensitivity was then examined in a longitudinal design as a mechanism linking stressful life events to changes in anxiety symptoms. Stressful life events, anxiety sensitivity, and internalizing symptoms were assessed in a diverse community sample of adolescents (N = 1,065) at 3 time points spanning 7 months. The results indicated that stressful life events were longitudinally associated with increases in anxiety sensitivity and that certain types of stressful life events, specifically events related to health and events related to family discord, were differentially predictive of increases in anxiety sensitivity. Moreover, anxiety sensitivity mediated the longitudinal relation between stressful life events and anxiety symptoms. Evidence was also found for the predictive specificity of anxiety sensitivity to symptoms of anxiety but not depression.

A parametric sensitivity study for single-stage-to-orbit hypersonic vehicles using trajectory optimization

NASA Astrophysics Data System (ADS)

Lovell, T. Alan; Schmidt, D. K.

1994-03-01

The class of hypersonic vehicle configurations with single stage-to-orbit (SSTO) capability reflect highly integrated airframe and propulsion systems. These designs are also known to exhibit a large degree of interaction between the airframe and engine dynamics. Consequently, even simplified hypersonic models are characterized by tightly coupled nonlinear equations of motion. In addition, hypersonic SSTO vehicles present a major system design challenge; the vehicle's overall mission performance is a function of its subsystem efficiencies including structural, aerodynamic, propulsive, and operational. Further, all subsystem efficiencies are interrelated, hence, independent optimization of the subsystems is not likely to lead to an optimum design. Thus, it is desired to know the effect of various subsystem efficiencies on overall mission performance. For the purposes of this analysis, mission performance will be measured in terms of the payload weight inserted into orbit. In this report, a trajectory optimization problem is formulated for a generic hypersonic lifting body for a specified orbit-injection mission. A solution method is outlined, and results are detailed for the generic vehicle, referred to as the baseline model. After evaluating the performance of the baseline model, a sensitivity study is presented to determine the effect of various subsystem efficiencies on mission performance. This consists of performing a parametric analysis of the basic design parameters, generating a matrix of configurations, and determining the mission performance of each configuration. Also, the performance loss due to constraining the total head load experienced by the vehicle is evaluated. The key results from this analysis include the formulation of the sizing problem for this vehicle class using trajectory optimization, characteristics of the optimal trajectories, and the subsystem design sensitivities.

A parametric sensitivity study for single-stage-to-orbit hypersonic vehicles using trajectory optimization

NASA Technical Reports Server (NTRS)

Lovell, T. Alan; Schmidt, D. K.

1994-01-01

The class of hypersonic vehicle configurations with single stage-to-orbit (SSTO) capability reflect highly integrated airframe and propulsion systems. These designs are also known to exhibit a large degree of interaction between the airframe and engine dynamics. Consequently, even simplified hypersonic models are characterized by tightly coupled nonlinear equations of motion. In addition, hypersonic SSTO vehicles present a major system design challenge; the vehicle's overall mission performance is a function of its subsystem efficiencies including structural, aerodynamic, propulsive, and operational. Further, all subsystem efficiencies are interrelated, hence, independent optimization of the subsystems is not likely to lead to an optimum design. Thus, it is desired to know the effect of various subsystem efficiencies on overall mission performance. For the purposes of this analysis, mission performance will be measured in terms of the payload weight inserted into orbit. In this report, a trajectory optimization problem is formulated for a generic hypersonic lifting body for a specified orbit-injection mission. A solution method is outlined, and results are detailed for the generic vehicle, referred to as the baseline model. After evaluating the performance of the baseline model, a sensitivity study is presented to determine the effect of various subsystem efficiencies on mission performance. This consists of performing a parametric analysis of the basic design parameters, generating a matrix of configurations, and determining the mission performance of each configuration. Also, the performance loss due to constraining the total head load experienced by the vehicle is evaluated. The key results from this analysis include the formulation of the sizing problem for this vehicle class using trajectory optimization, characteristics of the optimal trajectories, and the subsystem design sensitivities.

Investigation of Fundamental Modeling and Thermal Performance Issues for a Metallic Thermal Protection System Design

NASA Technical Reports Server (NTRS)

Blosser, Max L.

2002-01-01

A study was performed to develop an understanding of the key factors that govern the performance of metallic thermal protection systems for reusable launch vehicles. A current advanced metallic thermal protection system (TPS) concept was systematically analyzed to discover the most important factors governing the thermal performance of metallic TPS. A large number of relevant factors that influence the thermal analysis and thermal performance of metallic TPS were identified and quantified. Detailed finite element models were developed for predicting the thermal performance of design variations of the advanced metallic TPS concept mounted on a simple, unstiffened structure. The computational models were also used, in an automated iterative procedure, for sizing the metallic TPS to maintain the structure below a specified temperature limit. A statistical sensitivity analysis method, based on orthogonal matrix techniques used in robust design, was used to quantify and rank the relative importance of the various modeling and design factors considered in this study. Results of the study indicate that radiation, even in small gaps between panels, can reduce significantly the thermal performance of metallic TPS, so that gaps should be eliminated by design if possible. Thermal performance was also shown to be sensitive to several analytical assumptions that should be chosen carefully. One of the factors that was found to have the greatest effect on thermal performance is the heat capacity of the underlying structure. Therefore the structure and TPS should be designed concurrently.

Design and development of pH-responsive HSPC:C12H25-PAA chimeric liposomes.

PubMed

Naziris, Nikolaos; Pippa, Natassa; Meristoudi, Anastasia; Pispas, Stergios; Demetzos, Costas

2017-06-01

The application of stimuli-responsive medical practices has emerged, in which pH-sensitive liposomes figure prominently. This study investigates the impact of the incorporation of different amounts of pH-sensitive polymer, C 12 H 25 -PAA (poly(acrylic acid) with a hydrophobic end group) in l-α-phosphatidylcholine, hydrogenated (Soy) (HSPC) phospholipidic bilayers, with respect to biomimicry and functionality. PAA is a poly(carboxylic acid) molecule, classified as a pH-sensitive polymer, whose pH-sensitivity is attributed to its regulative -COOH groups, which are protonated under acidic pH (pKa ∼4.2). Our concern was to fully characterize, in a biophysical and thermodynamical manner, the mixed nanoassemblies arising from the combination of the two biomaterials. At first, we quantified the physicochemical characteristics and physical stability of the prepared chimeric nanosystems. Then, we studied their thermotropic behavior, through measurement of thermodynamical parameters, using Differential Scanning Calorimetry (DSC). Finally, the loading and release of indomethacin (IND) were evaluated, as well as the physicochemical properties and stability of the nanocarriers incorporating it. As expected, thermodynamical findings are in line with physicochemical results and also explain the loading and release profiles of IND. The novelty of this investigation is the utilization of these pH-sensitive chimeric advanced Drug Delivery nano Systems (aDDnSs) in targeted drug delivery which relies entirely on the biophysics and thermodynamics between such designs and the physiological membranes and environment of living organisms.

Sampled-Data Techniques Applied to a Digital Controller for an Altitude Autopilot

NASA Technical Reports Server (NTRS)

Schmidt, Stanley F.; Harper, Eleanor V.

1959-01-01

Sampled-data theory, using the Z transformation, is applied to the design of a digital controller for an aircraft-altitude autopilot. Particular attention is focused on the sensitivity of the design to parameter variations and the abruptness of the response, that is, the normal acceleration required to carry out a transient maneuver. Consideration of these two characteristics of the system has shown that the finite settling time design method produces an unacceptable system, primarily because of the high sensitivity of the response to parameter variations, although abruptness can be controlled by increasing the sampling period. Also demonstrated is the importance of having well-damped poles or zeros if cancellation is attempted in the design methods. A different method of smoothing the response and obtaining a design which is not excessively sensitive is proposed, and examples are carried through to demonstrate the validity of the procedure. This method is based on design concepts of continuous systems, and it is shown that if no pole-zero cancellations are allowed in the design, one can obtain a response which is not too abrupt, is relatively insensitive to parameter variations, and is not sensitive to practical limits on control-surface rate. This particular design also has the simplest possible pulse transfer function for the digital controller. Simulation techniques and root loci are used for the verification of the design philosophy.

Topology optimization based design of unilateral NMR for generating a remote homogeneous field.

PubMed

Wang, Qi; Gao, Renjing; Liu, Shutian

2017-06-01

This paper presents a topology optimization based design method for the design of unilateral nuclear magnetic resonance (NMR), with which a remote homogeneous field can be obtained. The topology optimization is actualized by seeking out the optimal layout of ferromagnetic materials within a given design domain. The design objective is defined as generating a sensitive magnetic field with optimal homogeneity and maximal field strength within a required region of interest (ROI). The sensitivity of the objective function with respect to the design variables is derived and the method for solving the optimization problem is presented. A design example is provided to illustrate the utility of the design method, specifically the ability to improve the quality of the magnetic field over the required ROI by determining the optimal structural topology for the ferromagnetic poles. Both in simulations and experiments, the sensitive region of the magnetic field achieves about 2 times larger than that of the reference design, validating validates the feasibility of the design method. Copyright © 2017. Published by Elsevier Inc.

Early Childhood Studies in Israel: Using DAP as a Framework.

ERIC Educational Resources Information Center

Dayan, Yael

2000-01-01

This article describes the evolution of a graduate program in early childhood studies at the Hebrew University of Jerusalem. The training model was designed to enhance sensitivity and responsiveness toward children, and uses developmentally appropriate practices as a theoretical basis. (JPB)

Yoga therapy for promoting emotional sensitivity in University students.

PubMed

Ganpat, Tikhe Sham; Dash, Sasmita; Ramarao, Nagendra Hongasandra

2014-01-01

Students need emotional intelligence (EI) for their better academic excellence. There are three important psychological dimensions of EI: Emotional sensitivity (ES), emotional maturity (EM) and emotional competency (EC), which motivate students to recognize truthfully, interpret honestly and handle tactfully the dynamics of their behavioral pattern. The study was designed to assess ES in the students undergoing yoga therapy program in the form of yoga instructor's course (YIC) module. One hundred and eighty four YIC students with 25.77 ± 4.85 years of mean age participated in this study of 21 days duration (a single group pre-post design). The ES data was collected before (pre) and after (post) YIC module using Emotional Quotient test developed by Dr Dalip Singh and Dr N K Chadha. Means, standard deviations, Kolmogorov-Smirnov test, and Wilcoxon signed rank test were used for analyzing the data with the help of SPSS 16. The data analysis showed 3.63% significant increase (P < 0.01) in ES. The present study suggests that YIC module can result in improvement of ES among university students, thus paving the way for their academic success. Additional well-designed studies are needed before a strong recommendation can be made.

32 CFR 651.29 - Determining when to use a CX (screening criteria).

Code of Federal Regulations, 2013 CFR

2013-07-01

...; areas of critical environmental concern; or other areas of high environmental sensitivity. (4) Cultural... agricultural lands; coastal zones; designated wilderness or wilderness study areas; wild and scenic rivers...

32 CFR 651.29 - Determining when to use a CX (screening criteria).

Code of Federal Regulations, 2014 CFR

2014-07-01

...; areas of critical environmental concern; or other areas of high environmental sensitivity. (4) Cultural... agricultural lands; coastal zones; designated wilderness or wilderness study areas; wild and scenic rivers...

32 CFR 651.29 - Determining when to use a CX (screening criteria).

Code of Federal Regulations, 2012 CFR

2012-07-01

...; areas of critical environmental concern; or other areas of high environmental sensitivity. (4) Cultural... agricultural lands; coastal zones; designated wilderness or wilderness study areas; wild and scenic rivers...

[Effects of a breast feeding promotion program for working women].

PubMed

Yoon, Ji-Won; Park, Young-Joo

2008-12-01

The purpose of this study was to measure the effects of a breast feeding promotion program for working women on breast feeding continuation, mother-infant attachment, and maternal sensitivity. The design of this study is nonequivalent control group design with repeated measures. There were significant differences in breast feeding continuation between two groups at each time point except 2 days and 1 week after delivery. The scores of mother-infant attachment and maternal sensitivity of experimental group were higher than those of the control group, but there were no significant differences between two groups. Although some modifications in contents and administration will be required to increase the effectiveness of the program, breast feeding promotion program for working women can be an effective nursing intervention which can facilitate breast feeding continuation and mother-infant relationships.

Sensitivity study of Space Station Freedom operations cost and selected user resources

NASA Technical Reports Server (NTRS)

Accola, Anne; Fincannon, H. J.; Williams, Gregory J.; Meier, R. Timothy

1990-01-01

The results of sensitivity studies performed to estimate probable ranges for four key Space Station parameters using the Space Station Freedom's Model for Estimating Space Station Operations Cost (MESSOC) are discussed. The variables examined are grouped into five main categories: logistics, crew, design, space transportation system, and training. The modification of these variables implies programmatic decisions in areas such as orbital replacement unit (ORU) design, investment in repair capabilities, and crew operations policies. The model utilizes a wide range of algorithms and an extensive trial logistics data base to represent Space Station operations. The trial logistics data base consists largely of a collection of the ORUs that comprise the mature station, and their characteristics based on current engineering understanding of the Space Station. A nondimensional approach is used to examine the relative importance of variables on parameters.

Design, synthesis, and evaluation of caffeic acid amides as synergists to sensitize fluconazole-resistant Candida albicans to fluconazole.

PubMed

Dai, Li; Zang, Chengxu; Tian, Shujuan; Liu, Wei; Tan, Shanlun; Cai, Zhan; Ni, Tingjunhong; An, Maomao; Li, Ran; Gao, Yue; Zhang, Dazhi; Jiang, Yuanying

2015-01-01

A series of caffeic acid amides were designed, synthesized, and their synergistic activity with fluconazole against fluconazole-resistant Candida albicans was evaluated in vitro. The title caffeic acid amides 3-30 except 26 exhibited potent activity, and the subsequent SAR study was conducted. Compound 3, 5, 21, and 34c, at a concentration of 1.0 μg/ml, decreased the MIC₈₀ of fluconazole from 128.0 μg/ml to 1.0-0.5 μg/ml against the fluconazole-resistant C. albicans. This result suggests that the caffeic acid amides, as synergists, can sensitize drug-resistant fungi to fluconazole. The SAR study indicated that the dihydroxyl groups and the amido groups linking to phenyl or heterocyclic rings are the important pharmacophores of the caffeic acid amides.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Lijuan; Gonder, Jeff; Burton, Evan

This study evaluates the costs and benefits associated with the use of a plug-in hybrid electric bus and determines the cost effectiveness relative to a conventional bus and a hybrid electric bus. A sensitivity sweep analysis was performed over a number of a different battery sizes, charging powers, and charging stations. The net present value was calculated for each vehicle design and provided the basis for the design evaluation. In all cases, given present day economic assumptions, the conventional bus achieved the lowest net present value while the optimal plug-in hybrid electric bus scenario reached lower lifetime costs than themore » hybrid electric bus. The study also performed parameter sensitivity analysis under low market potential assumptions and high market potential assumptions. The net present value of plug-in hybrid electric bus is close to that of conventional bus.« less

When stress gets into your head: Socioeconomic risk, executive functions, and maternal sensitivity across childrearing contexts.

PubMed

Sturge-Apple, Melissa L; Jones, Hannah R; Suor, Jennifer H

2017-03-01

Socioeconomic adversity has been targeted as a key upstream mechanism with robust pathogenic effects on maternal caregiving. Although research has demonstrated the negative repercussions of socioeconomic difficulties, little research has documented potential mechanisms underlying this association. Toward increasing understanding, the present study examined how maternal working memory capacity and inhibitory control may mediate associations between socioeconomic risk and change in maternal sensitivity across free-play and discipline caregiving contexts. This study used a longitudinal design, and utilized a socioeconomically diverse sample of 185 mothers and their 3.5-year-old toddlers. Multi-informants and methods were used to assess constructs. Findings revealed that maternal EF mediated associations between socioeconomic risk and parenting sensitivity with specific effects for working memory and baseline sensitivity and inhibitory control and change in sensitivity as childrearing demands increased. Results are interpreted within emerging conceptual frameworks regarding the role of parental neurocognitive functioning and caregiving. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

A Trigger-based Design for Evaluating the Safety of In Utero Antiretroviral Exposure in Uninfected Children of Human Immunodeficiency Virus-Infected Mothers

PubMed Central

Williams, Paige L.; Seage, George R.; Van Dyke, Russell B.; Siberry, George K.; Griner, Raymond; Tassiopoulos, Katherine; Yildirim, Cenk; Read, Jennifer S.; Huo, Yanling; Hazra, Rohan; Jacobson, Denise L.; Mofenson, Lynne M.; Rich, Kenneth

2012-01-01

The Pediatric HIV/AIDS Cohort Study’s Surveillance Monitoring of ART Toxicities Study is a prospective cohort study conducted at 22 US sites between 2007 and 2011 that was designed to evaluate the safety of in utero antiretroviral drug exposure in children not infected with human immunodeficiency virus who were born to mothers who were infected. This ongoing study uses a “trigger-based” design; that is, initial assessments are conducted on all children, and only those meeting certain thresholds or “triggers” undergo more intensive evaluations to determine whether they have had an adverse event (AE). The authors present the estimated rates of AEs for each domain of interest in the Surveillance Monitoring of ART Toxicities Study. They also evaluated the efficiency of this trigger-based design for estimating AE rates and for testing associations between in utero exposures to antiretroviral drugs and AEs. The authors demonstrate that estimated AE rates from the trigger-based design are unbiased after correction for the sensitivity of the trigger for identifying AEs. Even without correcting for bias based on trigger sensitivity, the trigger approach is generally more efficient for estimating AE rates than is evaluating a random sample of the same size. Minor losses in efficiency when comparing AE rates between persons exposed and unexposed in utero to particular antiretroviral drugs or drug classes were observed under most scenarios. PMID:22491086

Theoretical Design on a Series of Novel Bicyclic and Cage Nitramines as High Energy Density Compounds.

PubMed

Pan, Yong; Zhu, Weihua

2017-11-30

We designed four bicyclic nitramines and three cage nitramines by incorporating -N(NO 2 )-CH 2 -N(NO 2 )-, -N(NO 2 )-, and -O- linkages based on the HMX (1,3,5,7-tetranitro-1,3,5,7-tetrazocane) framework. Then, their electronic structure, heats of formation, energetic properties, strain energy, thermal stability, and impact sensitivity were systematically studied using density functional theory (DFT). Compared to the parent compound HMX, all the title compounds have much higher density, better detonation properties, and better oxygen balance. Among them, four compounds have extraordinary high detonation properties (D > 9.70 km/s and P > 44.30 GPa). Moreover, most of the title compounds exhibit better thermal stability and lower impact sensitivity than CL-20 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane) or HNHAA (hexanitrohexaazaadamantane). Thus, all of the seven new nitramine compounds are promising candidates for high energy density compounds. In particular, five compounds exhibit a best combination of better oxygen balance, good thermal stability, excellent detonation properties superior to or comparable to CL-20 or HNHAA, and lower impact sensitivity than CL-20 or HNHAA. The results indicate that our unusual design strategy that constructing bicyclic or cage nitramines based on the HMX framework by incorporating the intramolecular linkages is very useful for developing novel energetic compounds with excellent detonation performance and low sensitivity.

Stability of a pH-sensitive polymer matrix

DOE Office of Scientific and Technical Information (OSTI.GOV)

Northrup, M.A.; Langry, K.; Angel, S.M.

1990-03-01

A ratiometric pH-sensitive fluorescent dye (hydroxypyrenetrisulfonic acid) was covalently attached to an acrylamide polymer. These pH-sensitive copolymers were either covalently bonded to the end of an optical fiber or polymerized into separate gels. Long-term, accelerated aging studies were performed on the fibers and gels in 43{degree}C distilled H{sub 2}O. The fiber-immobilized optrodes gave good pH responses for up to 2 months. The pH-sensitive gels were physically attached to optical fibers and gave very good pH responses for over one year. These physically immobilized, one-year-old, pH-sensitive copolymers provided optrodes with linear pH responses between pH 6 and 8 and resolution greatermore » than 0.25 pH unit. A simple photostability experiment on these optrodes showed that they were very photostable. The results of this study indicate that pH-sensitive copolymers in a simple optrode design can be employed as pH sensors with useful lifetimes exceeding one year. 11 refs., 6 figs.« less

Sensitivity of different Trypanosoma vivax specific primers for the diagnosis of livestock trypanosomosis using different DNA extraction methods.

PubMed

Gonzales, J L; Loza, A; Chacon, E

2006-03-15

There are several T. vivax specific primers developed for PCR diagnosis. Most of these primers were validated under different DNA extraction methods and study designs leading to heterogeneity of results. The objective of the present study was to validate PCR as a diagnostic test for T. vivax trypanosomosis by means of determining the test sensitivity of different published specific primers with different sample preparations. Four different DNA extraction methods were used to test the sensitivity of PCR with four different primer sets. DNA was extracted directly from whole blood samples, blood dried on filter papers or blood dried on FTA cards. The results showed that the sensitivity of PCR with each primer set was highly dependant of the sample preparation and DNA extraction method. The highest sensitivities for all the primers tested were determined using DNA extracted from whole blood samples, while the lowest sensitivities were obtained when DNA was extracted from filter paper preparations. To conclude, the obtained results are discussed and a protocol for diagnosis and surveillance for T. vivax trypanosomosis is recommended.

Development of animal models and sandwich-ELISA tests to detect the allergenicity and antigenicity of fining agent residues in wines.

PubMed

Lifrani, Awatif; Dos Santos, Jacinthe; Dubarry, Michel; Rautureau, Michelle; Blachier, Francois; Tome, Daniel

2009-01-28

Food allergy can cause food-related anaphylaxis. Food allergen labeling is the principal means of protecting sensitized individuals. This motivated European Directive 2003/89 on the labeling of ingredients or additives that could trigger adverse reactions, which has been in effect since 2005. During this study, we developed animal models with allergy to ovalbumin, caseinate, and isinglass in order to be able to detect fining agent residues that could induce anaphylactic reactions in sensitized mice. The second aim of the study was to design sandwich ELISA tests specific to each fining agent in order to detect their residue antigenicity, both during wine processing and in commercially available bottled wines. Sensitized mice and sandwich ELISA methods were established to test a vast panel of wines. The results showed that although they were positive to our highly sensitive sandwich-ELISA tests, some commercially available wines are not allergenic in sensitized mice. Commercially available bottled wines made using standardized processes, fining, maturation, and filtration, do not therefore represent any risk of anaphylactic reactions in sensitized mice.

Multicolour LEDs in educational demonstrations of physics and optometry

NASA Astrophysics Data System (ADS)

Paulins, Paulis; Ozolinsh, Maris

2014-07-01

LED light sources are used to design experimental setup for university courses teaching human color vision. The setup allows to demonstrate various vision characteristics and to apply for student practical exercises to study eye spectral sensitivity in different spectral range using heterochromatic flicker photometry. Technique can be used in laboratory works for students to acquire knowledge in visual perception, basics of electronics and measuring, or it can be applied as fully computer control experiment. Besides studies of the eye spectral sensitivity students can practice in trichromatic color matching and other visual perception tasks

Orbit Transfer Vehicle (OTV) engine phase A study

NASA Technical Reports Server (NTRS)

Mellish, J. A.

1978-01-01

Requirements for the orbit transfer vehicle engine were examined. Engine performance/weight sensitivities, the effect of a service life of 300 start/shutdown cycles between overalls on the maximum engine operating pressure, and the sensitivity of the engine design point (i.e., thrust chamber pressure and nozzle area ratio) to the performance requirements specified are among the factors studied. Preliminary engine systems analyses were conducted on the stage combustion, expander, and gas generator engine cycles. Hydrogen and oxygen pump discharge pressure requirements are shown for various engine cycles. Performance of the engine cycles is compared.

Conducting Qualitative Research on Stigmatizing Conditions with Military Populations

PubMed Central

Lincoln, Martha L.; Ames, Genevieve M.; Moore, Roland S.

2016-01-01

This article addresses the conduct of qualitative research regarding sensitive or stigmatizing topics with military populations, and provides suggestions for implementing culturally responsive and effective data collection with these groups. Given high rates of underreporting of sensitive and stigmatizing conditions in the military, qualitative methods have potential to shed light on phenomena that are not well understood. Drawing on a study of U.S. Army National Guard personnel by civilian anthropologists, we present lessons learned and argue that the value of similar studies can be maximized by culturally responsive research design. PMID:27722033

Sensitivity, Specificity, and Predictive Values of Pediatric Metabolic Syndrome Components in Relation to Adult Metabolic Syndrome: The Princeton LRC Follow-up Study

PubMed Central

Huang, Terry T-K; Nansel, Tonja R.; Belsheim, Allen R.; Morrison, John A.

2008-01-01

Objective To estimate the sensitivity, specificity, and predictive values of pediatric metabolic syndrome (MetS) components (obesity, fasting glucose, triglycerides, high-density lipoprotein, and blood pressure) at various cutoffs in relation to adult MetS. Study design Data from the NHLBI Lipid Research Clinics (LRC) Princeton Prevalence Study (1973–76) and the Princeton Follow-up Study (PFS, 2000-4) were used to calculate sensitivity, specificity, and positive and negative predictive values for each component at a given cutoff, as well as for aggregates of components. Results Individual pediatric components alone showed low to moderate sensitivity, high specificity, and moderate predictive values in relation to adult MetS. When all five pediatric MetS components were considered, the presence of at least one abnormality had higher sensitivity for adult MetS than individual components alone. When multiple abnormalities were mandatory for MetS, positive predictive value was high and sensitivity was low. Childhood body mass alone showed neither high sensitivity nor high positive predictive value for adult MetS. Conclusions Considering multiple metabolic variables in childhood can improve the predictive utility for adult MetS, compared to each component or body mass alone. MetS variables may be useful for identifying some at risk children for prevention interventions. PMID:18206687

Assurance of Learning and Study Abroad: A Case Study

ERIC Educational Resources Information Center

Rexeisen, Richard J.; Al-Khatib, Jamal

2009-01-01

Most academic programs are now held accountable for measuring student-learning outcomes. This article reports the results of an assurance of learning (AOL) project designed to measure the impact of study abroad on the development of ethical reasoning, intercultural sensitivity, and environmental attitudes. The Association to Advance Collegiate…

Variational Methods in Sensitivity Analysis and Optimization for Aerodynamic Applications

NASA Technical Reports Server (NTRS)

Ibrahim, A. H.; Hou, G. J.-W.; Tiwari, S. N. (Principal Investigator)

1996-01-01

Variational methods (VM) sensitivity analysis, which is the continuous alternative to the discrete sensitivity analysis, is employed to derive the costate (adjoint) equations, the transversality conditions, and the functional sensitivity derivatives. In the derivation of the sensitivity equations, the variational methods use the generalized calculus of variations, in which the variable boundary is considered as the design function. The converged solution of the state equations together with the converged solution of the costate equations are integrated along the domain boundary to uniquely determine the functional sensitivity derivatives with respect to the design function. The determination of the sensitivity derivatives of the performance index or functional entails the coupled solutions of the state and costate equations. As the stable and converged numerical solution of the costate equations with their boundary conditions are a priori unknown, numerical stability analysis is performed on both the state and costate equations. Thereafter, based on the amplification factors obtained by solving the generalized eigenvalue equations, the stability behavior of the costate equations is discussed and compared with the state (Euler) equations. The stability analysis of the costate equations suggests that the converged and stable solution of the costate equation is possible only if the computational domain of the costate equations is transformed to take into account the reverse flow nature of the costate equations. The application of the variational methods to aerodynamic shape optimization problems is demonstrated for internal flow problems at supersonic Mach number range. The study shows, that while maintaining the accuracy of the functional sensitivity derivatives within the reasonable range for engineering prediction purposes, the variational methods show a substantial gain in computational efficiency, i.e., computer time and memory, when compared with the finite difference sensitivity analysis.

Research design considerations for single-dose analgesic clinical trials in acute pain: IMMPACT recommendations.

PubMed

Cooper, Stephen A; Desjardins, Paul J; Turk, Dennis C; Dworkin, Robert H; Katz, Nathaniel P; Kehlet, Henrik; Ballantyne, Jane C; Burke, Laurie B; Carragee, Eugene; Cowan, Penney; Croll, Scott; Dionne, Raymond A; Farrar, John T; Gilron, Ian; Gordon, Debra B; Iyengar, Smriti; Jay, Gary W; Kalso, Eija A; Kerns, Robert D; McDermott, Michael P; Raja, Srinivasa N; Rappaport, Bob A; Rauschkolb, Christine; Royal, Mike A; Segerdahl, Märta; Stauffer, Joseph W; Todd, Knox H; Vanhove, Geertrui F; Wallace, Mark S; West, Christine; White, Richard E; Wu, Christopher

2016-02-01

This article summarizes the results of a meeting convened by the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT) on key considerations and best practices governing the design of acute pain clinical trials. We discuss the role of early phase clinical trials, including pharmacokinetic-pharmacodynamic (PK-PD) trials, and the value of including both placebo and active standards of comparison in acute pain trials. This article focuses on single-dose and short-duration trials with emphasis on the perioperative and study design factors that influence assay sensitivity. Recommendations are presented on assessment measures, study designs, and operational factors. Although most of the methodological advances have come from studies of postoperative pain after dental impaction, bunionectomy, and other surgeries, the design considerations discussed are applicable to many other acute pain studies conducted in different settings.

Citation searches are more sensitive than keyword searches to identify studies using specific measurement instruments

PubMed Central

Linder, Suzanne K.; Kamath, Geetanjali R.; Pratt, Gregory F.; Saraykar, Smita S.; Volk, Robert J.

2015-01-01

Objective To compare the effectiveness of two search methods in identifying studies that used the Control Preferences Scale (CPS), a healthcare decision-making instrument commonly used in clinical settings. Study Design & Setting We searched the literature using two methods: 1) keyword searching using variations of “control preferences scale” and 2) cited reference searching using two seminal CPS publications. We searched three bibliographic databases [PubMed, Scopus, Web of Science (WOS)] and one full-text database (Google Scholar). We report precision and sensitivity as measures of effectiveness. Results Keyword searches in bibliographic databases yielded high average precision (90%), but low average sensitivity (16%). PubMed was the most precise, followed closely by Scopus and WOS. The Google Scholar keyword search had low precision (54%) but provided the highest sensitivity (70%). Cited reference searches in all databases yielded moderate sensitivity (45–54%), but precision ranged from 35–75% with Scopus being the most precise. Conclusion Cited reference searches were more sensitive than keyword searches, making it a more comprehensive strategy to identify all studies that use a particular instrument. Keyword searches provide a quick way of finding some but not all relevant articles. Goals, time and resources should dictate the combination of which methods and databases are used. PMID:25554521

Context sensitive design : thinking beyond the pavement : documentation of workshop development and training.

DOT National Transportation Integrated Search

2005-05-01

This report documents the development and presentation of the workshop titled Thinking Beyond the Pavement A Workshop on Context Sensitive Design. Work began on the workshop development in 1998 after the Kentucky Transportation Cabinet was ...

Optimal packing for cascaded regenerative transmission based on phase sensitive amplifiers.

PubMed

Sorokina, Mariia; Sygletos, Stylianos; Ellis, Andrew D; Turitsyn, Sergei

2013-12-16

We investigate the transmission performance of advanced modulation formats in nonlinear regenerative channels based on cascaded phase sensitive amplifiers. We identify the impact of amplitude and phase noise dynamics along the transmission line and show that after a cascade of regenerators, densely packed single ring PSK constellations outperform multi-ring constellations. The results of this study will greatly simplify the design of future nonlinear regenerative channels for ultra-high capacity transmission.

Constellations of elliptical inclined lunar orbits providing polar and global coverage

NASA Technical Reports Server (NTRS)

Ely, Todd A.; Lieb, Erica

2005-01-01

Prior results have developed a methodology for selecting a long-lived constellation of 3 satellites that provide persistent, stable coverage to either the North or South Pole with no requirement for stationkeeping under the influence of only gravitational perturbations. In the present study, the sensitivity of this coverage in the presence of non-gravitational forces is determined, and a design strategy is formulated that minimizes any potential sensitivity to these accelerations.

Secure FAST: Security Enhancement in the NATO Time Sensitive Targeting Tool

DTIC Science & Technology

2010-11-01

designed to aid in the tracking and prosecuting of Time Sensitive Targets. The FAST tool provides user level authentication and authorisation in terms...level authentication and authorisation in terms of security. It uses operating system level security but does not provide application level security for...and collaboration tool, designed to aid in the tracking and prosecuting of Time Sensitive Targets. The FAST tool provides user level authentication and

Epidemiology and Clinical Research Design, Part 2: Principles.

PubMed

Manja, Veena; Lakshminrusimha, Satyan

This is the third article covering core knowledge in scholarly activities for neonatal physicians. In this article, we discuss various principles of epidemiology and clinical research design. A basic knowledge of these principles is necessary for conducting clinical research and for proper interpretation of studies. This article reviews bias and confounding, causation, incidence and prevalence, decision analysis, cost-effectiveness, sensitivity analysis, and measurement.

Design enhancement tools in MSC/NASTRAN

NASA Technical Reports Server (NTRS)

Wallerstein, D. V.

1984-01-01

Design sensitivity is the calculation of derivatives of constraint functions with respect to design variables. While a knowledge of these derivatives is useful in its own right, the derivatives are required in many efficient optimization methods. Constraint derivatives are also required in some reanalysis methods. It is shown where the sensitivity coefficients fit into the scheme of a basic organization of an optimization procedure. The analyzer is to be taken as MSC/NASTRAN. The terminator program monitors the termination criteria and ends the optimization procedure when the criteria are satisfied. This program can reside in several plances: in the optimizer itself, in a user written code, or as part of the MSC/EOS (Engineering Operating System) MSC/EOS currently under development. Since several excellent optimization codes exist and since they require such very specialized technical knowledge, the optimizer under the new MSC/EOS is considered to be selected and supplied by the user to meet his specific needs and preferences. The one exception to this is a fully stressed design (FSD) based on simple scaling. The gradients are currently supplied by various design sensitivity options now existing in MSC/NASTRAN's design sensitivity analysis (DSA).

Personal use of hair dyes and the risk of bladder cancer: results of a meta-analysis.

PubMed Central

Huncharek, Michael; Kupelnick, Bruce

2005-01-01

OBJECTIVE: This study examined the methodology of observational studies that explored an association between personal use of hair dye products and the risk of bladder cancer. METHODS: Data were pooled from epidemiological studies using a general variance-based meta-analytic method that employed confidence intervals. The outcome of interest was a summary relative risk (RRs) reflecting the risk of bladder cancer development associated with use of hair dye products vs. non-use. Sensitivity analyses were performed to explain any observed statistical heterogeneity and to explore the influence of specific study characteristics of the summary estimate of effect. RESULTS: Initially combining homogenous data from six case-control and one cohort study yielded a non-significant RR of 1.01 (0.92, 1.11), suggesting no association between hair dye use and bladder cancer development. Sensitivity analyses examining the influence of hair dye type, color, and study design on this suspected association showed that uncontrolled confounding and design limitations contributed to a spurious non-significant summary RR. The sensitivity analyses yielded statistically significant RRs ranging from 1.22 (1.11, 1.51) to 1.50 (1.30, 1.98), indicating that personal use of hair dye products increases bladder cancer risk by 22% to 50% vs. non-use. CONCLUSION: The available epidemiological data suggest an association between personal use of hair dye products and increased risk of bladder cancer. PMID:15736329

Current estimates of the cure fraction: a feasibility study of statistical cure for breast and colorectal cancer.

PubMed

Stedman, Margaret R; Feuer, Eric J; Mariotto, Angela B

2014-11-01

The probability of cure is a long-term prognostic measure of cancer survival. Estimates of the cure fraction, the proportion of patients "cured" of the disease, are based on extrapolating survival models beyond the range of data. The objective of this work is to evaluate the sensitivity of cure fraction estimates to model choice and study design. Data were obtained from the Surveillance, Epidemiology, and End Results (SEER)-9 registries to construct a cohort of breast and colorectal cancer patients diagnosed from 1975 to 1985. In a sensitivity analysis, cure fraction estimates are compared from different study designs with short- and long-term follow-up. Methods tested include: cause-specific and relative survival, parametric mixture, and flexible models. In a separate analysis, estimates are projected for 2008 diagnoses using study designs including the full cohort (1975-2008 diagnoses) and restricted to recent diagnoses (1998-2008) with follow-up to 2009. We show that flexible models often provide higher estimates of the cure fraction compared to parametric mixture models. Log normal models generate lower estimates than Weibull parametric models. In general, 12 years is enough follow-up time to estimate the cure fraction for regional and distant stage colorectal cancer but not for breast cancer. 2008 colorectal cure projections show a 15% increase in the cure fraction since 1985. Estimates of the cure fraction are model and study design dependent. It is best to compare results from multiple models and examine model fit to determine the reliability of the estimate. Early-stage cancers are sensitive to survival type and follow-up time because of their longer survival. More flexible models are susceptible to slight fluctuations in the shape of the survival curve which can influence the stability of the estimate; however, stability may be improved by lengthening follow-up and restricting the cohort to reduce heterogeneity in the data. Published by Oxford University Press 2014.

Molecular engineering of sensitizers for dye-sensitized solar cell applications.

PubMed

Giribabu, Lingamallu; Kanaparthi, Ravi Kumar; Velkannan, Veerapandian

2012-06-01

Dye-sensitized solar cells (DSSCs) have attracted considerable attention in recent years as they offer the possibility of low-cost conversion of photovoltaic energy. This account focuses on recent advances in molecular design and technological aspects of sensitizers based on metal complexes, metal-free organics and tetrapyrrolic compounds which include porphyrins, phthalocyanines as well as corroles. Special attention has been paid to the design principles of these dyes, and co-sensitization, an emerging technique to extend the absorption range, is also discussed as a way to improve the performance of the device. This account also focuses on recent advances of efficient ruthenium sensitizers as well as other metal complexes and their applications in DSSCs. Recent developments in the area of metal-free organic and tetrapyrrolic sensitizers are also discussed. Copyright © 2012 The Japan Chemical Journal Forum and Wiley Periodicals, Inc.

Chemically Designed Metallic/Insulating Hybrid Nanostructures with Silver Nanocrystals for Highly Sensitive Wearable Pressure Sensors.

PubMed

Kim, Haneun; Lee, Seung-Wook; Joh, Hyungmok; Seong, Mingi; Lee, Woo Seok; Kang, Min Su; Pyo, Jun Beom; Oh, Soong Ju

2018-01-10

With the increase in interest in wearable tactile pressure sensors for e-skin, researches to make nanostructures to achieve high sensitivity have been actively conducted. However, limitations such as complex fabrication processes using expensive equipment still exist. Herein, simple lithography-free techniques to develop pyramid-like metal/insulator hybrid nanostructures utilizing nanocrystals (NCs) are demonstrated. Ligand-exchanged and unexchanged silver NC thin films are used as metallic and insulating components, respectively. The interfaces of each NC layer are chemically engineered to create discontinuous insulating layers, i.e., spacers for improved sensitivity, and eventually to realize fully solution-processed pressure sensors. Device performance analysis with structural, chemical, and electronic characterization and conductive atomic force microscopy study reveals that hybrid nanostructure based pressure sensor shows an enhanced sensitivity of higher than 500 kPa -1 , reliability, and low power consumption with a wide range of pressure sensing. Nano-/micro-hierarchical structures are also designed by combining hybrid nanostructures with conventional microstructures, exhibiting further enhanced sensing range and achieving a record sensitivity of 2.72 × 10 4 kPa -1 . Finally, all-solution-processed pressure sensor arrays with high pixel density, capable of detecting delicate signals with high spatial selectivity much better than the human tactile threshold, are introduced.

Sensitivity of measuring the progress in financial risk protection to survey design and its socioeconomic and demographic determinants: A case study in Rwanda.

PubMed

Lu, Chunling; Liu, Kai; Li, Lingling; Yang, Yuhong

2017-04-01

Reliable and comparable information on households with catastrophic health expenditure (HCHE) is crucial for monitoring and evaluating our progress towards achieving universal financial risk protection. This study aims to investigate the sensitivity of measuring the progress in financial risk protection to survey design and its socioeconomic and demographic determinants. Using the Rwanda Integrated Living Conditions Survey in 2005 and 2010/2011, we derived the level and trend of the percentage of the HCHE using out-of-pocket health spending data derived from (1) a health module with a two-week recall period and six (2005)/seven (2010/2011) survey questions (Method 1) and (2) a consumption module with a four-week/ten-/12-month recall period and 11(2005)/24 (2010/2011) questions (Method 2). Using multilevel logistic regression analysis, we investigated the household socioeconomic and demographic characteristics that affected the sensitivity of estimating the HCHE to survey design. We found that Method 1 generated a significantly higher HCHE estimate (9.2%, 95% confidence interval 8.4%-10.0%) than Method2 (7.4%, 6.6%-8.1%) in 2005 and lower estimate (5.6%, 5.2%-6.1%) than Method 2 (8.2%, 7.6%-8.7%) in 2010/2011. The estimated trends of the HCHE using the two methods were not consistent between the two years. A household's size, its income quintile, having no under-five children, and educational level of its head were positively associated with the consistency of its HCHE status when using the two survey methods. Estimates of the progress in financial risk protection, especially among the most vulnerable households, are sensitive to survey design. These results are robust to various thresholds of catastrophic health spending. Future work must focus on mitigating survey effects through the development of statistical tools. Copyright © 2017 Elsevier Ltd. All rights reserved.

Sensitivity of measuring the progress in financial risk protection to survey design and its socioeconomic and demographic determinants: A case study in Rwanda

PubMed Central

Lu, Chunling; Liu, Kai; Li, Lingling; Yang, Yuhong

2017-01-01

Reliable and comparable information on households with catastrophic health expenditure (HCHE) is crucial for monitoring and evaluating our progress towards achieving universal financial risk protection. This study aims to investigate the sensitivity of measuring the progress in financial risk protection to survey design and its socioeconomic and demographic determinants. Using the Rwanda Integrated Living Conditions Survey in 2005 and 2010/2011, we derived the level and trend of the percentage of the HCHE using out-of-pocket health spending data derived from (1) a health module with a two-week recall period and six (2005)/seven (2010/2011) survey questions (Method 1) and (2) a consumption module with a four-week/ten-/12-month recall period and 11(2005)/24 (2010/2011) questions (Method 2). Using multilevel logistic regression analysis, we investigated the household socioeconomic and demographic characteristics that affected the sensitivity of estimating the HCHE to survey design. We found that Method 1 generated a significantly higher HCHE estimate (9.2%, 95% confidence interval 8.4%–10.0%) than Method2 (7.4%, 6.6%–8.1%) in 2005 and lower estimate (5.6%, 5.2%–6.1%) than Method 2 (8.2%, 7.6% –8.7%) in 2010/2011. The estimated trends of the HCHE using the two methods were not consistent between the two years. A household's size, its income quintile, having no under-five children, and educational level of its head were positively associated with the consistency of its HCHE status when using the two survey methods. Estimates of the progress in financial risk protection, especially among the most vulnerable households, are sensitive to survey design. These results are robust to various thresholds of catastrophic health spending. Future work must focus on mitigating survey effects through the development of statistical tools. PMID:28189819

TRIMELLITIC ANHYDRIDE-INDUCED EOSINOPHILLA IN A MOUSE MODEL OF OCCUPATIONAL ASTHMA

EPA Science Inventory

Trimellitic anhydride (TMA) is a low molecular weight chemical known to cause occupational asthma. The present study was designed to determine if TMA could elicit eosinophil infiltration into the lung of a sensitized mouse similarly to previous studies with the protein allergen ...

The Insensitive Ruins It All: Compositional and Compilational Influences of Social Sensitivity on Collective Intelligence in Groups.

PubMed

Meslec, Nicoleta; Aggarwal, Ishani; Curseu, Petru L

2016-01-01

A group's collective intelligence reflects its capacity to perform well across a variety of cognitive tasks and it transcends the individual intelligence of its members. Previous research shows that group members' social sensitivity is a potential antecedent of collective intelligence, yet it is still unclear whether individual or group-level indices are responsible for the positive association between social sensitivity and collective intelligence. In a comprehensive manner, we test the extent to which both compositional (lowest and highest individual score) and compilational aspects (emergent group level) of social sensitivity are associated with collective intelligence. This study has implications for research that explores groups as information processors, and for group design as it indicates how a group should be composed with respect to social sensitivity if the group is to reach high levels of collective intelligence. Our empirical results indicate that collectively intelligent groups are those in which the least socially sensitive group member has a rather high score on social sensitivity. Differently stated, (socially sensitive) group members cannot compensate for the lack of social sensitivity of the other group members.

Integrated multidisciplinary design optimization using discrete sensitivity analysis for geometrically complex aeroelastic configurations

NASA Astrophysics Data System (ADS)

Newman, James Charles, III

1997-10-01

The first two steps in the development of an integrated multidisciplinary design optimization procedure capable of analyzing the nonlinear fluid flow about geometrically complex aeroelastic configurations have been accomplished in the present work. For the first step, a three-dimensional unstructured grid approach to aerodynamic shape sensitivity analysis and design optimization has been developed. The advantage of unstructured grids, when compared with a structured-grid approach, is their inherent ability to discretize irregularly shaped domains with greater efficiency and less effort. Hence, this approach is ideally suited for geometrically complex configurations of practical interest. In this work the time-dependent, nonlinear Euler equations are solved using an upwind, cell-centered, finite-volume scheme. The discrete, linearized systems which result from this scheme are solved iteratively by a preconditioned conjugate-gradient-like algorithm known as GMRES for the two-dimensional cases and a Gauss-Seidel algorithm for the three-dimensional; at steady-state, similar procedures are used to solve the accompanying linear aerodynamic sensitivity equations in incremental iterative form. As shown, this particular form of the sensitivity equation makes large-scale gradient-based aerodynamic optimization possible by taking advantage of memory efficient methods to construct exact Jacobian matrix-vector products. Various surface parameterization techniques have been employed in the current study to control the shape of the design surface. Once this surface has been deformed, the interior volume of the unstructured grid is adapted by considering the mesh as a system of interconnected tension springs. Grid sensitivities are obtained by differentiating the surface parameterization and the grid adaptation algorithms with ADIFOR, an advanced automatic-differentiation software tool. To demonstrate the ability of this procedure to analyze and design complex configurations of practical interest, the sensitivity analysis and shape optimization has been performed for several two- and three-dimensional cases. In twodimensions, an initially symmetric NACA-0012 airfoil and a high-lift multielement airfoil were examined. For the three-dimensional configurations, an initially rectangular wing with uniform NACA-0012 cross-sections was optimized; in addition, a complete Boeing 747-200 aircraft was studied. Furthermore, the current study also examines the effect of inconsistency in the order of spatial accuracy between the nonlinear fluid and linear shape sensitivity equations. The second step was to develop a computationally efficient, high-fidelity, integrated static aeroelastic analysis procedure. To accomplish this, a structural analysis code was coupled with the aforementioned unstructured grid aerodynamic analysis solver. The use of an unstructured grid scheme for the aerodynamic analysis enhances the interaction compatibility with the wing structure. The structural analysis utilizes finite elements to model the wing so that accurate structural deflections may be obtained. In the current work, parameters have been introduced to control the interaction of the computational fluid dynamics and structural analyses; these control parameters permit extremely efficient static aeroelastic computations. To demonstrate and evaluate this procedure, static aeroelastic analysis results for a flexible wing in low subsonic, high subsonic (subcritical), transonic (supercritical), and supersonic flow conditions are presented.

Multidisciplinary optimization of controlled space structures with global sensitivity equations

NASA Technical Reports Server (NTRS)

Padula, Sharon L.; James, Benjamin B.; Graves, Philip C.; Woodard, Stanley E.

1991-01-01

A new method for the preliminary design of controlled space structures is presented. The method coordinates standard finite element structural analysis, multivariable controls, and nonlinear programming codes and allows simultaneous optimization of the structures and control systems of a spacecraft. Global sensitivity equations are a key feature of this method. The preliminary design of a generic geostationary platform is used to demonstrate the multidisciplinary optimization method. Fifteen design variables are used to optimize truss member sizes and feedback gain values. The goal is to reduce the total mass of the structure and the vibration control system while satisfying constraints on vibration decay rate. Incorporating the nonnegligible mass of actuators causes an essential coupling between structural design variables and control design variables. The solution of the demonstration problem is an important step toward a comprehensive preliminary design capability for structures and control systems. Use of global sensitivity equations helps solve optimization problems that have a large number of design variables and a high degree of coupling between disciplines.

Buckling Imperfection Sensitivity of Axially Compressed Orthotropic Cylinders

NASA Technical Reports Server (NTRS)

Schultz, Marc R.; Nemeth, Michael P.

2010-01-01

Structural stability is a major consideration in the design of lightweight shell structures. However, the theoretical predictions of geometrically perfect structures often considerably over predict the buckling loads of inherently imperfect real structures. It is reasonably well understood how the shell geometry affects the imperfection sensitivity of axially compressed cylindrical shells; however, the effects of shell anisotropy on the imperfection sensitivity is less well understood. In the present paper, the development of an analytical model for assessing the imperfection sensitivity of axially compressed orthotropic cylinders is discussed. Results from the analytical model for four shell designs are compared with those from a general-purpose finite-element code, and good qualitative agreement is found. Reasons for discrepancies are discussed, and potential design implications of this line of research are discussed.

Interfacing of differential-capacitive biomimetic hair flow-sensors for optimal sensitivity

NASA Astrophysics Data System (ADS)

Dagamseh, A. M. K.; Bruinink, C. M.; Wiegerink, R. J.; Lammerink, T. S. J.; Droogendijk, H.; Krijnen, G. J. M.

2013-03-01

Biologically inspired sensor-designs are investigated as a possible path to surpass the performance of more traditionally engineered designs. Inspired by crickets, artificial hair sensors have shown the ability to detect minute flow signals. This paper addresses developments in the design, fabrication, interfacing and characterization of biomimetic hair flow-sensors towards sensitive high-density arrays. Improvement of the electrode design of the hair sensors has resulted in a reduction of the smallest hair movements that can be measured. In comparison to the arrayed hairs-sensor design, the detection-limit was arguably improved at least twelve-fold, down to 1 mm s-1 airflow amplitude at 250 Hz as measured in a bandwidth of 3 kHz. The directivity pattern closely resembles a figure-of-eight. These sensitive hair-sensors open possibilities for high-resolution spatio-temporal flow pattern observations.

Using an Adjoint Approach to Eliminate Mesh Sensitivities in Computational Design

NASA Technical Reports Server (NTRS)

Nielsen, Eric J.; Park, Michael A.

2006-01-01

An algorithm for efficiently incorporating the effects of mesh sensitivities in a computational design framework is introduced. The method is based on an adjoint approach and eliminates the need for explicit linearizations of the mesh movement scheme with respect to the geometric parameterization variables, an expense that has hindered practical large-scale design optimization using discrete adjoint methods. The effects of the mesh sensitivities can be accounted for through the solution of an adjoint problem equivalent in cost to a single mesh movement computation, followed by an explicit matrix-vector product scaling with the number of design variables and the resolution of the parameterized surface grid. The accuracy of the implementation is established and dramatic computational savings obtained using the new approach are demonstrated using several test cases. Sample design optimizations are also shown.

Using an Adjoint Approach to Eliminate Mesh Sensitivities in Computational Design

NASA Technical Reports Server (NTRS)

Nielsen, Eric J.; Park, Michael A.

2005-01-01

An algorithm for efficiently incorporating the effects of mesh sensitivities in a computational design framework is introduced. The method is based on an adjoint approach and eliminates the need for explicit linearizations of the mesh movement scheme with respect to the geometric parameterization variables, an expense that has hindered practical large-scale design optimization using discrete adjoint methods. The effects of the mesh sensitivities can be accounted for through the solution of an adjoint problem equivalent in cost to a single mesh movement computation, followed by an explicit matrix-vector product scaling with the number of design variables and the resolution of the parameterized surface grid. The accuracy of the implementation is established and dramatic computational savings obtained using the new approach are demonstrated using several test cases. Sample design optimizations are also shown.

Influence of some design parameters on the thermal performance of domestic refrigerator appliances

NASA Astrophysics Data System (ADS)

Rebora, Alessandro; Senarega, Maurizio; Tagliafico, Luca A.

2006-07-01

This paper presents a thermal study on chest-freezers, the small refrigerators used in domestic and supermarket applications. A thermal and energy model of a particular kind of these refrigerators, the “hot-wall” (or “skin condenser”) refrigerator, is developed and used to perform sensitivity and design optimisation analysis for given working temperatures and useful volume of the refrigerated cell. A finite-element heat transfer model of the refrigerator box is coupled to the complete thermodynamic model of the refrigerating plant, including real working conditions (compressor efficiency, friction pressure losses and so on). A sensitivity study of the main design parameters affecting the global refrigerator performance has been developed (for fixed working temperatures) with reference to the thickness of the metallic plates, to the evaporator and condenser tube diameters and to the evaporator tube pitch (with fixed evaporator-to-condenser tube pitch ratio). The results obtained show that the proposed sensitivity analysis can yield quite reliable results (in comparison with much more complex, albeit more accurate mathematical optimisation algorithms) using small computational resources. The great importance of 2-D heat conduction in the metallic plates is shown, evidencing how the plate thickness and the evaporator and condenser tube diameters affect the global performance of the system according to the well-known “fin efficiency” effect. The influence of the evaporator and condenser tube diameters on the friction pressure losses is also outlined. Some practical suggestions are made in conclusion, regarding the criteria which should be adopted in the thermal design of a hot-wall refrigerator.

Optimization of Heat Exchangers with Dimpled Surfaces to Improve the Performance in Thermoelectric Generators Using a Kriging Model

NASA Astrophysics Data System (ADS)

Li, Shuai; Wang, Yiping; Wang, Tao; Yang, Xue; Deng, Yadong; Su, Chuqi

2017-05-01

Thermoelectric generators (TEGs) have become a topic of interest for vehicle exhaust energy recovery. Electrical power generation is deeply influenced by temperature differences, temperature uniformity and topological structures of TEGs. When the dimpled surfaces are adopted in heat exchangers, the heat transfer rates can be augmented with a minimal pressure drop. However, the temperature distribution shows a large gradient along the flow direction which has adverse effects on the power generation. In the current study, the heat exchanger performance was studied in a computational fluid dynamics (CFD) model. The dimple depth, dimple print diameter, and channel height were chosen as design variables. The objective function was defined as a combination of average temperature, temperature uniformity and pressure loss. The optimal Latin hypercube method was used to determine the experiment points as a method of design of the experiment in order to analyze the sensitivity of the design variables. A Kriging surrogate model was built and verified according to the database resulting from the CFD simulation. A multi-island genetic algorithm was used to optimize the structure in the heat exchanger based on the surrogate model. The results showed that the average temperature of the heat exchanger was most sensitive to the dimple depth. The pressure loss and temperature uniformity were most sensitive to the parameter of channel rear height, h 2. With an optimal design of channel structure, the temperature uniformity can be greatly improved compared with the initial exchanger, and the additional pressure loss also increased.

Probabilistic Structural Evaluation of Uncertainties in Radiator Sandwich Panel Design

NASA Technical Reports Server (NTRS)

Kuguoglu, Latife; Ludwiczak, Damian

2006-01-01

The Jupiter Icy Moons Orbiter (JIMO) Space System is part of the NASA's Prometheus Program. As part of the JIMO engineering team at NASA Glenn Research Center, the structural design of the JIMO Heat Rejection Subsystem (HRS) is evaluated. An initial goal of this study was to perform sensitivity analyses to determine the relative importance of the input variables on the structural responses of the radiator panel. The desire was to let the sensitivity analysis information identify the important parameters. The probabilistic analysis methods illustrated here support this objective. The probabilistic structural performance evaluation of a HRS radiator sandwich panel was performed. The radiator panel structural performance was assessed in the presence of uncertainties in the loading, fabrication process variables, and material properties. The stress and displacement contours of the deterministic structural analysis at mean probability was performed and results presented. It is followed by a probabilistic evaluation to determine the effect of the primitive variables on the radiator panel structural performance. Based on uncertainties in material properties, structural geometry and loading, the results of the displacement and stress analysis are used as an input file for the probabilistic analysis of the panel. The sensitivity of the structural responses, such as maximum displacement and maximum tensile and compressive stresses of the facesheet in x and y directions and maximum VonMises stresses of the tube, to the loading and design variables is determined under the boundary condition where all edges of the radiator panel are pinned. Based on this study, design critical material and geometric parameters of the considered sandwich panel are identified.

Tunable wavefront coded imaging system based on detachable phase mask: Mathematical analysis, optimization and underlying applications

NASA Astrophysics Data System (ADS)

Zhao, Hui; Wei, Jingxuan

2014-09-01

The key to the concept of tunable wavefront coding lies in detachable phase masks. Ojeda-Castaneda et al. (Progress in Electronics Research Symposium Proceedings, Cambridge, USA, July 5-8, 2010) described a typical design in which two components with cosinusoidal phase variation operate together to make defocus sensitivity tunable. The present study proposes an improved design and makes three contributions: (1) A mathematical derivation based on the stationary phase method explains why the detachable phase mask of Ojeda-Castaneda et al. tunes the defocus sensitivity. (2) The mathematical derivations show that the effective bandwidth wavefront coded imaging system is also tunable by making each component of the detachable phase mask move asymmetrically. An improved Fisher information-based optimization procedure was also designed to ascertain the optimal mask parameters corresponding to specific bandwidth. (3) Possible applications of the tunable bandwidth are demonstrated by simulated imaging.

Ultrastable lasers based on vibration insensitive cavities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Millo, J.; Magalhaes, D. V.; Mandache, C.

2009-05-15

We present two ultrastable lasers based on two vibration insensitive cavity designs, one with vertical optical axis geometry, the other horizontal. Ultrastable cavities are constructed with fused silica mirror substrates, shown to decrease the thermal noise limit, in order to improve the frequency stability over previous designs. Vibration sensitivity components measured are equal to or better than 1.5x10{sup -11}/m s{sup -2} for each spatial direction, which shows significant improvement over previous studies. We have tested the very low dependence on the position of the cavity support points, in order to establish that our designs eliminate the need for fine tuningmore » to achieve extremely low vibration sensitivity. Relative frequency measurements show that at least one of the stabilized lasers has a stability better than 5.6x10{sup -16} at 1 s, which is the best result obtained for this length of cavity.« less

Theory of mind as a predictor of maternal sensitivity in women with severe mental illness.

PubMed

Rigby, J; Conroy, S; Miele-Norton, M; Pawlby, S; Happé, F

2016-07-01

Research has shown that maternal mental illness can affect mother-infant interactions with implications for infant outcomes. Severe and chronic mental illness (SMI), particularly schizophrenia, is associated with the greatest risk. Schizophrenia is also associated with impairments in attribution of mental states, 'theory of mind' (ToM). Recent attachment research has suggested that maternal mentalizing skills are strongly associated with attachment outcome in infants. To date, no research has explored the relationship between ToM and maternal sensitivity in mothers with SMI using standard tests of ToM. The present study was designed as an exploratory study in order to investigate this. A total of 40 women with SMI in the postpartum period were administered a battery of ToM tasks and general neuropsychological tasks. The women were also filmed in an unstructured play session with their infants, which was coded for maternal sensitivity using the Crittenden CARE-Index. One ToM task, the Frith-Happé Animations, predicted maternal sensitivity across all diagnoses. There was also an effect of diagnosis, with lower sensitivity observed in women with schizophrenia. ToM impairments did not fully explain the effect of diagnosis on sensitivity. Mothers of girls were rated as being more sensitive than mothers of boys. The results suggest that ToM is a significant predictor of maternal sensitivity across all mental health diagnoses, extending the results of studies focusing on healthy populations. Clinical interventions emphasizing the importance of understanding the perspective of the infant may enhance maternal sensitivity.

Design constraints of the LST fine guidance sensor

NASA Technical Reports Server (NTRS)

Wissinger, A. B.

1975-01-01

The LST Fine Guidance Sensor design is shaped by the rate of occurrence of suitable guide stars, the competition for telescope focal plane space with the Science Instruments, and the sensitivity of candidate image motion sensors. The relationship between these parameters is presented, and sensitivity to faint stars is shown to be of prime importance. An interferometric technique of image motion sensing is shown to have improved sensitivity and, therefore, a reduced focal plane area requirement in comparison with other candidate techniques (image-splitting prism and image dissector tube techniques). Another design requirement is speed in acquiring the guide star in order to maximize the time available for science observations. The design constraints are shown parametrically, and modelling results are presented.

Relative Accuracy of Nucleic Acid Amplification Tests and Culture in Detecting Chlamydia in Asymptomatic Men

PubMed Central

Cheng, Hong; Macaluso, Maurizio; Vermund, Sten H.; Hook, Edward W.

2001-01-01

Published estimates of the sensitivity and specificity of PCR and ligase chain reaction (LCR) for detecting Chlamydia trachomatis are potentially biased because of study design limitations (confirmation of test results was limited to subjects who were PCR or LCR positive but culture negative). Relative measures of test accuracy are less prone to bias in incomplete study designs. We estimated the relative sensitivity (RSN) and relative false-positive rate (RFP) for PCR and LCR versus cell culture among 1,138 asymptomatic men and evaluated the potential bias of RSN and RFP estimates. PCR and LCR testing in urine were compared to culture of urethral specimens. Discordant results (PCR or LCR positive, but culture negative) were confirmed by using a sequence including the other DNA amplification test, direct fluorescent antibody testing, and a DNA amplification test to detect chlamydial major outer membrane protein. The RSN estimates for PCR and LCR were 1.45 (95% confidence interval [CI] = 1.3 to 1.7) and 1.49 (95% CI = 1.3 to 1.7), respectively, indicating that both methods are more sensitive than culture. Very few false-positive results were found, indicating that the specificity levels of PCR, LCR, and culture are high. The potential bias in RSN and RFP estimates were <5 and <20%, respectively. The estimation of bias is based on the most likely and probably conservative parameter settings. If the sensitivity of culture is between 60 and 65%, then the true sensitivity of PCR and LCR is between 90 and 97%. Our findings indicate that PCR and LCR are significantly more sensitive than culture, while the three tests have similar specificities. PMID:11682509

Application research on the sensitivity of porous silicon

NASA Astrophysics Data System (ADS)

Xu, Gaobin; Xi, Ye; Chen, Xing; Ma, Yuanming

2017-09-01

Applications based on sensitive property of porous silicon (PSi) were researched. As a kind of porous material, the feasibility of PSi as a getter material was studied. Five groups of samples with different parameters were prepared. The gas-sensing property of PSi was studied by the test system and suitable parameters of PSi were also discussed. Meanwhile a novel structure of humidity sensor, using porous silicon as humidity-sensitive material, based on MEMS process has been successfully designed. The humidity-sensing properties were studied by a test system. Because of the polysilicon layer deposited upon the PSi layer, the humidity sensor can realize a quick dehumidification by itself. To extend service life and reduce the effect of the environment, a passivation layer (Si3N4) was also deposited on the surface of electrodes. The result indicated the novel humidity sensor presented high sensitivity (1.1 pF/RH%), low hysteresis, low temperature coefficient (0.5%RH/°C) and high stability.

Failure Bounding And Sensitivity Analysis Applied To Monte Carlo Entry, Descent, And Landing Simulations

NASA Technical Reports Server (NTRS)

Gaebler, John A.; Tolson, Robert H.

2010-01-01

In the study of entry, descent, and landing, Monte Carlo sampling methods are often employed to study the uncertainty in the designed trajectory. The large number of uncertain inputs and outputs, coupled with complicated non-linear models, can make interpretation of the results difficult. Three methods that provide statistical insights are applied to an entry, descent, and landing simulation. The advantages and disadvantages of each method are discussed in terms of the insights gained versus the computational cost. The first method investigated was failure domain bounding which aims to reduce the computational cost of assessing the failure probability. Next a variance-based sensitivity analysis was studied for the ability to identify which input variable uncertainty has the greatest impact on the uncertainty of an output. Finally, probabilistic sensitivity analysis is used to calculate certain sensitivities at a reduced computational cost. These methods produce valuable information that identifies critical mission parameters and needs for new technology, but generally at a significant computational cost.

First- and Second-Order Sensitivity Analysis of a P-Version Finite Element Equation Via Automatic Differentiation

NASA Technical Reports Server (NTRS)

Hou, Gene

1998-01-01

Sensitivity analysis is a technique for determining derivatives of system responses with respect to design parameters. Among many methods available for sensitivity analysis, automatic differentiation has been proven through many applications in fluid dynamics and structural mechanics to be an accurate and easy method for obtaining derivatives. Nevertheless, the method can be computational expensive and can require a high memory space. This project will apply an automatic differentiation tool, ADIFOR, to a p-version finite element code to obtain first- and second- order then-nal derivatives, respectively. The focus of the study is on the implementation process and the performance of the ADIFOR-enhanced codes for sensitivity analysis in terms of memory requirement, computational efficiency, and accuracy.

Shot noise-limited Cramér-Rao bound and algorithmic sensitivity for wavelength shifting interferometry

NASA Astrophysics Data System (ADS)

Chen, Shichao; Zhu, Yizheng

2017-02-01

Sensitivity is a critical index to measure the temporal fluctuation of the retrieved optical pathlength in quantitative phase imaging system. However, an accurate and comprehensive analysis for sensitivity evaluation is still lacking in current literature. In particular, previous theoretical studies for fundamental sensitivity based on Gaussian noise models are not applicable to modern cameras and detectors, which are dominated by shot noise. In this paper, we derive two shot noiselimited theoretical sensitivities, Cramér-Rao bound and algorithmic sensitivity for wavelength shifting interferometry, which is a major category of on-axis interferometry techniques in quantitative phase imaging. Based on the derivations, we show that the shot noise-limited model permits accurate estimation of theoretical sensitivities directly from measured data. These results can provide important insights into fundamental constraints in system performance and can be used to guide system design and optimization. The same concepts can be generalized to other quantitative phase imaging techniques as well.

Design of a Model Execution Framework: Repetitive Object-Oriented Simulation Environment (ROSE)

NASA Technical Reports Server (NTRS)

Gray, Justin S.; Briggs, Jeffery L.

2008-01-01

The ROSE framework was designed to facilitate complex system analyses. It completely divorces the model execution process from the model itself. By doing so ROSE frees the modeler to develop a library of standard modeling processes such as Design of Experiments, optimizers, parameter studies, and sensitivity studies which can then be applied to any of their available models. The ROSE framework accomplishes this by means of a well defined API and object structure. Both the API and object structure are presented here with enough detail to implement ROSE in any object-oriented language or modeling tool.

Studies of low-mass star formation with the large deployable reflector

NASA Technical Reports Server (NTRS)

Hollenbach, D. J.; Tielens, Alexander G. G. M.

1984-01-01

Estimates are made of the far-infrared and submillimeter continuum and line emission from regions of low mass star formation. The intensity of this emission is compared with the sensitivity of the large deployable reflector (LDR), a large space telescope designed for this wavelength range. The proposed LDR is designed to probe the temperature, density, chemical structure, and the velocity field of the collapsing envelopes of these protostars. The LDR is also designed to study the accretion shocks on the cores and circumstellar disks of low-mass protostars, and to detect shock waves driven by protostellar winds.

A Risk Management Framework to Characterize Black Swan Risks: A Case Study of Lightning Effects on Insensitive High Explosives

NASA Astrophysics Data System (ADS)

Sanders, Gary A.

Effective and efficient risk management processes include the use of high fidelity modeling and simulation during the concept exploration phase as part of the technology and risk assessment activities, with testing and evaluation tasks occurring in later design development phases. However, some safety requirements and design architectures may be dominated by the low probability/high consequence "Black Swan" vulnerabilities that require very early testing to characterize and efficiently mitigate. Failure to address these unique risks has led to catastrophic systems failures including the space shuttle Challenger, Deepwater Horizon, Fukushima nuclear reactor, and Katrina dike failures. Discovering and addressing these risks later in the design and development process can be very costly or even lead to project cancellation. This paper examines the need for risk management process adoption of early hazard phenomenology testing to inform the technical risk assessment, requirements definition and conceptual design. A case study of the lightning design vulnerability of the insensitive high explosives being used in construction, mining, demolition, and defense industries will be presented to examine the impact of this vulnerability testing during the concept exploration phase of the design effort. While these insensitive high explosives are far less sensitive to accidental initiation by fire, impact, friction or even electrical stimuli, their full range of sensitivities have not been characterized and ensuring safe engineering design and operations during events such as lightning storms requires vulnerability testing during the risk assessment phase.

Comprehensive Design Reliability Activities for Aerospace Propulsion Systems

NASA Technical Reports Server (NTRS)

Christenson, R. L.; Whitley, M. R.; Knight, K. C.

2000-01-01

This technical publication describes the methodology, model, software tool, input data, and analysis result that support aerospace design reliability studies. The focus of these activities is on propulsion systems mechanical design reliability. The goal of these activities is to support design from a reliability perspective. Paralleling performance analyses in schedule and method, this requires the proper use of metrics in a validated reliability model useful for design, sensitivity, and trade studies. Design reliability analysis in this view is one of several critical design functions. A design reliability method is detailed and two example analyses are provided-one qualitative and the other quantitative. The use of aerospace and commercial data sources for quantification is discussed and sources listed. A tool that was developed to support both types of analyses is presented. Finally, special topics discussed include the development of design criteria, issues of reliability quantification, quality control, and reliability verification.

Automatic differentiation for design sensitivity analysis of structural systems using multiple processors

NASA Technical Reports Server (NTRS)

Nguyen, Duc T.; Storaasli, Olaf O.; Qin, Jiangning; Qamar, Ramzi

1994-01-01

An automatic differentiation tool (ADIFOR) is incorporated into a finite element based structural analysis program for shape and non-shape design sensitivity analysis of structural systems. The entire analysis and sensitivity procedures are parallelized and vectorized for high performance computation. Small scale examples to verify the accuracy of the proposed program and a medium scale example to demonstrate the parallel vector performance on multiple CRAY C90 processors are included.

Simulation study comparing the helmet-chin PET with a cylindrical PET of the same number of detectors

NASA Astrophysics Data System (ADS)

Ahmed, Abdella M.; Tashima, Hideaki; Yoshida, Eiji; Nishikido, Fumihiko; Yamaya, Taiga

2017-06-01

There is a growing interest in developing brain PET scanners with high sensitivity and high spatial resolution for early diagnosis of neurodegenerative diseases and studies of brain functions. Sensitivity of the PET scanner can be improved by increasing the solid angle. However, conventional PET scanners are designed based on a cylindrical geometry, which may not be the most efficient design for brain imaging in terms of the balance between sensitivity and cost. We proposed a dedicated brain PET scanner based on a hemispheric shape detector and a chin detector (referred to as the helmet-chin PET), which is designed to maximize the solid angle by increasing the number of lines-of-response in the hemisphere. The parallax error, which PET scanners with a large solid angle tend to have, can be suppressed by the use of depth-of-interaction detectors. In this study, we carry out a realistic evaluation of the helmet-chin PET using Monte Carlo simulation based on the 4-layer GSO detector which consists of a 16  ×  16  ×  4 array of crystals with dimensions of 2.8  ×  2.8  ×  7.5 mm3. The purpose of this simulation is to show the gain in imaging performance of the helmet-chin PET compared with the cylindrical PET using the same number of detectors in each configuration. The sensitivity of the helmet-chin PET evaluated with a cylindrical phantom has a significant increase, especially at the top of the (field-of-view) FOV. The peak-NECR of the helmet-chin PET is 1.4 times higher compared to the cylindrical PET. The helmet-chin PET provides relatively low noise images throughout the FOV compared to the cylindrical PET which exhibits enhanced noise at the peripheral regions. The results show the helmet-chin PET can significantly improve the sensitivity and reduce the noise in the reconstructed images.

Physical effects of mechanical design parameters on photon sensitivity and spatial resolution performance of a breast-dedicated PET system.

PubMed

Spanoudaki, V C; Lau, F W Y; Vandenbroucke, A; Levin, C S

2010-11-01

This study aims to address design considerations of a high resolution, high sensitivity positron emission tomography scanner dedicated to breast imaging. The methodology uses a detailed Monte Carlo model of the system structures to obtain a quantitative evaluation of several performance parameters. Special focus was given to the effect of dense mechanical structures designed to provide mechanical robustness and thermal regulation to the minuscule and temperature sensitive detectors. For the energies of interest around the photopeak (450-700 keV energy window), the simulation results predict a 6.5% reduction in the single photon detection efficiency and a 12.5% reduction in the coincidence photon detection efficiency in the case that the mechanical structures are interspersed between the detectors. However for lower energies, a substantial increase in the number of detected events (approximately 14% and 7% for singles at a 100-200 keV energy window and coincidences at a lower energy threshold of 100 keV, respectively) was observed with the presence of these structures due to backscatter. The number of photon events that involve multiple interactions in various crystal elements is also affected by the presence of the structures. For photon events involving multiple interactions among various crystal elements, the coincidence photon sensitivity is reduced by as much as 20% for a point source at the center of the field of view. There is no observable effect on the intrinsic and the reconstructed spatial resolution and spatial resolution uniformity. Mechanical structures can have a considerable effect on system sensitivity, especially for systems processing multi-interaction photon events. This effect, however, does not impact the spatial resolution. Various mechanical structure designs are currently under evaluation in order to achieve optimum trade-off between temperature stability, accurate detector positioning, and minimum influence on system performance.

Physical effects of mechanical design parameters on photon sensitivity and spatial resolution performance of a breast-dedicated PET system

PubMed Central

Spanoudaki, V. C.; Lau, F. W. Y.; Vandenbroucke, A.; Levin, C. S.

2010-01-01

Purpose: This study aims to address design considerations of a high resolution, high sensitivity positron emission tomography scanner dedicated to breast imaging. Methods: The methodology uses a detailed Monte Carlo model of the system structures to obtain a quantitative evaluation of several performance parameters. Special focus was given to the effect of dense mechanical structures designed to provide mechanical robustness and thermal regulation to the minuscule and temperature sensitive detectors. Results: For the energies of interest around the photopeak (450–700 keV energy window), the simulation results predict a 6.5% reduction in the single photon detection efficiency and a 12.5% reduction in the coincidence photon detection efficiency in the case that the mechanical structures are interspersed between the detectors. However for lower energies, a substantial increase in the number of detected events (approximately 14% and 7% for singles at a 100–200 keV energy window and coincidences at a lower energy threshold of 100 keV, respectively) was observed with the presence of these structures due to backscatter. The number of photon events that involve multiple interactions in various crystal elements is also affected by the presence of the structures. For photon events involving multiple interactions among various crystal elements, the coincidence photon sensitivity is reduced by as much as 20% for a point source at the center of the field of view. There is no observable effect on the intrinsic and the reconstructed spatial resolution and spatial resolution uniformity. Conclusions: Mechanical structures can have a considerable effect on system sensitivity, especially for systems processing multi-interaction photon events. This effect, however, does not impact the spatial resolution. Various mechanical structure designs are currently under evaluation in order to achieve optimum trade-off between temperature stability, accurate detector positioning, and minimum influence on system performance. PMID:21158296

The System Design, Engineering Architecture, and Preliminary Results of a Lower-Cost High-Sensitivity High-Resolution Positron Emission Mammography Camera.

PubMed

Zhang, Yuxuan; Ramirez, Rocio A; Li, Hongdi; Liu, Shitao; An, Shaohui; Wang, Chao; Baghaei, Hossain; Wong, Wai-Hoi

2010-02-01

A lower-cost high-sensitivity high-resolution positron emission mammography (PEM) camera is developed. It consists of two detector modules with the planar detector bank of 20 × 12 cm(2). Each bank has 60 low-cost PMT-Quadrant-Sharing (PQS) LYSO blocks arranged in a 10 × 6 array with two types of geometries. One is the symmetric 19.36 × 19.36 mm(2) block made of 1.5 × 1.5 × 10 mm(3) crystals in a 12 × 12 array. The other is the 19.36 × 26.05 mm(2) asymmetric block made of 1.5 × 1.9 × 10 mm(3) crystals in 12 × 13 array. One row (10) of the elongated blocks are used along one side of the bank to reclaim the half empty PMT photocathode in the regular PQS design to reduce the dead area at the edge of the module. The bank has a high overall crystal packing fraction of 88%, which results in a very high sensitivity. Mechanical design and electronics have been developed for low-cost, compactness, and stability purposes. Each module has four Anger-HYPER decoding electronics that can handle a count-rate of 3 Mcps for single events. A simple two-module coincidence board with a hardware delay window for random coincidences has been developed with an adjustable window of 6 to 15 ns. Some of the performance parameters have been studied by preliminary tests and Monte Carlo simulations, including the crystal decoding map and the 17% energy resolution of the detectors, the point source sensitivity of 11.5% with 50 mm bank-to-bank distance, the 1.2 mm-spatial resolutions, 42 kcps peak Noise Equivalent Count Rate at 7.0-mCi total activity in human body, and the resolution phantom images. Those results show that the design goal of building a lower-cost, high-sensitivity, high-resolution PEM detector is achieved.

Flexible Packaging by Film-Assisted Molding for Microintegration of Inertia Sensors

PubMed Central

Hera, Daniel; Berndt, Armin; Günther, Thomas; Schmiel, Stephan; Harendt, Christine; Zimmermann, André

2017-01-01

Packaging represents an important part in the microintegration of sensors based on microelectromechanical system (MEMS). Besides miniaturization and integration density, functionality and reliability in combination with flexibility in packaging design at moderate costs and consequently high-mix, low-volume production are the main requirements for future solutions in packaging. This study investigates possibilities employing printed circuit board (PCB-)based assemblies to provide high flexibility for circuit designs together with film-assisted transfer molding (FAM) to package sensors. The feasibility of FAM in combination with PCB and MEMS as a packaging technology for highly sensitive inertia sensors is being demonstrated. The results prove the technology to be a viable method for damage-free packaging of stress- and pressure-sensitive MEMS. PMID:28653992

Design and characterization of a wearable macrobending fiber optic sensor for human joint angle determination

NASA Astrophysics Data System (ADS)

Silva, Ana S.; Catarino, André; Correia, Miguel V.; Frazão, Orlando

2013-12-01

The work presented here describes the development and characterization of intensity fiber optic sensor integrated in a specifically designed piece of garment to measure elbow flexion. The sensing head is based on macrobending incorporated in the garment, and the increase of curvature number was studied in order to investigate which scheme provided a good result in terms of sensitivity and repeatability. Results showed the configuration that assured a higher sensitivity (0.644 dBm/deg) and better repeatability was the one with four loops. Ultimately, this sensor can be used for rehabilitation purposes to monitor human joint angles, namely, elbow flexion on stroke survivors while performing the reach functional task, which is the most common upper-limb human gesture.

Does the Irlen[R] Method Bring about an Increase in Reading Scores on a Specific Test of Reading for Students Found to Have Scotopic Sensitivity Syndrome?

ERIC Educational Resources Information Center

Faraci, Marie Elaine

2009-01-01

The problem. The purpose of this study was to examine the effect of the Irlen[R] method's use of colored overlays on the reading achievement of 3rd-grade students who were identified as having Scotopic Sensitivity Syndrome/Irlen[R] Syndrome. Method. This was a true experimental, pre-test, post-test design. The Irlen[R] overlay, either present…

Implementation Status of a Ultra-Wideband Receiver Package for the next-generation Very Large Array

NASA Astrophysics Data System (ADS)

Lazio, T. Joseph W.; Velazco, Jose; Soriano, Melissa; Hoppe, Daniel; Russell, Damon; D'Addario, Larry; Long, Ezra; Bowen, James; Samoska, Lorene; Janzen, Andrew

2017-01-01

The next-generation Very Large Array (ngVLA) is a concept for a radio astronomical interferometric array operating in the frequency range 1.2 GHz to 116 GHz and designed to provide substantial improvements in sensitivity, angular resolution, and frequency coverage above the current Very Large Array (VLA). As notional design goals, it would have a continuous frequency coverage of 1.2 GHz to 48 GHz and be 10 times more sensitive than the VLA (and 25 times more sensitive than a 34 m diameter antenna of the Deep Space Network [DSN]). One of the key goals for the ngVLA is to reduce the operating costs without sacrificing performance. We are designing an ultra-wideband receiver package designed to operate across the 8 to 48 GHz frequency range, which can be contrasted to the current VLA, which covers this frequency range with five receiver packages. Reducing the number of receiving systems required to cover the full frequency range would reduce operating costs, and the objective of this work is to develop a prototype integrated feed-receiver package with a sensitivity performance comparable to current narrower band systems on radio telescopes and the DSN, but with a design that meets the requirement of low long-term operational costs. The ultra-wideband receiver package consists of a feed horn, low-noise amplifier (LNA), and down-converters to analog intermediate frequencies. Key features of this design are a quad-ridge feed horn with dielectric loading and a cryogenic receiver with a noise temperature of no more than 30 K at the low end of the band. We will report on the status of this receiver package development including the feed design and LNA implementation. We will present simulation studies of the feed horn including the insertion of dielectric components for improved illumination efficiencies across the band of interest. In addition, we will show experimental results of low-noise 35nm InP HEMT amplifier testing performed across the 8-50 GHz frequency range.Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

Sensitivity of Space Shuttle Weight and Cost to Structure Subsystem Weights

NASA Technical Reports Server (NTRS)

Wedge, T. E.; Williamson, R. P.

1973-01-01

Quantitative relationships between changes in space shuttle weights and costs with changes in weight of various portions of space shuttle structural subsystems are investigated. These sensitivity relationships, as they apply at each of three points in the development program (preliminary design phase, detail design phase, and test/operational phase) have been established for five typical space shuttle designs, each of which was responsive to the missions in the NASA Shuttle RFP, and one design was that selected by NASA.

Fluorescent hybridization probes for nucleic acid detection.

PubMed

Guo, Jia; Ju, Jingyue; Turro, Nicholas J

2012-04-01

Due to their high sensitivity and selectivity, minimum interference with living biological systems, and ease of design and synthesis, fluorescent hybridization probes have been widely used to detect nucleic acids both in vivo and in vitro. Molecular beacons (MBs) and binary probes (BPs) are two very important hybridization probes that are designed based on well-established photophysical principles. These probes have shown particular applicability in a variety of studies, such as mRNA tracking, single nucleotide polymorphism (SNP) detection, polymerase chain reaction (PCR) monitoring, and microorganism identification. Molecular beacons are hairpin oligonucleotide probes that present distinctive fluorescent signatures in the presence and absence of their target. Binary probes consist of two fluorescently labeled oligonucleotide strands that can hybridize to adjacent regions of their target and generate distinctive fluorescence signals. These probes have been extensively studied and modified for different applications by modulating their structures or using various combinations of fluorophores, excimer-forming molecules, and metal complexes. This review describes the applicability and advantages of various hybridization probes that utilize novel and creative design to enhance their target detection sensitivity and specificity.

Estimation of Stormwater Interception Rate for various LID Facilities

NASA Astrophysics Data System (ADS)

Kim, S.; Lee, O.; Choi, J.

2017-12-01

In this study, the stormwater interception rate is proposed to apply in the design of LID facilities. For this purpose, EPA-SWMM is built with some areas of Noksan National Industrial Complex where long-term observed stormwater data were monitored and stormwater interception rates for various design capacities of various LID facilities are estimated. While the sensitivity of stormwater interception rate according to design specifications of bio-retention and infiltration trench facilities is not large, the sensitivity of stormwater interception rate according to local rainfall characteristics is relatively big. As a result of comparing the present rainfall interception rate estimation method which is officially operated in Korea with the one proposed in this study, it will be presented that the present method is highly likely to overestimate the performance of the bio-retention and infiltration trench facilities. Finally, a new stormwater interception rate formulas for the bio-retention and infiltration trench LID facilities will be proposed. Acknowledgement This research was supported by a grant (2016000200002) from Public Welfare Technology Development Program funded by Ministry of Environment of Korean government.

The Impact of Biofuels on Climate Change from Marginal Land over East Asia using the RegCM4

NASA Astrophysics Data System (ADS)

Kim, S.; Lee, O.; Choi, J.

2016-12-01

In this study, the stormwater interception rate is proposed to apply in the design of LID facilities. For this purpose, EPA-SWMM is built with some areas of Noksan National Industrial Complex where long-term observed stormwater data were monitored and stormwater interception rates for various design capacities of various LID facilities are estimated. While the sensitivity of stormwater interception rate according to design specifications of bio-retention and infiltration trench facilities is not large, the sensitivity of stormwater interception rate according to local rainfall characteristics is relatively big. As a result of comparing the present rainfall interception rate estimation method which is officially operated in Korea with the one proposed in this study, it will be presented that the present method is highly likely to overestimate the performance of the bio-retention and infiltration trench facilities. Finally, a new stormwater interception rate formulas for the bio-retention and infiltration trench LID facilities will be proposed. Acknowledgement This research was supported by a grant (2016000200002) from Public Welfare Technology Development Program funded by Ministry of Environment of Korean government.

Aeroelastic considerations for torsionally soft rotors

NASA Technical Reports Server (NTRS)

Mantay, W. R.; Yeager, W. T., Jr.

1986-01-01

A research study was initiated to systematically determine the impact of selected blade tip geometric parameters on conformable rotor performance and loads characteristics. The model articulated rotors included baseline and torsionally soft blades with interchangeable tips. Seven blade tip designs were evaluated on the baseline rotor and six tip designs were tested on the torsionally soft blades. The designs incorporated a systemmatic variation in geometric parameters including sweep, taper, and anhedral. The rotors were evaluated in the NASA Langley Transonic Dynamics Tunnel at several advance ratios, lift and propulsive force values, and tip Mach numbers. A track sensitivity study was also conducted at several advance ratios for both rotors. Based on the test results, tip parameter variations generated significant rotor performance and loads differences for both baseline and torsionally soft blades. Azimuthal variation of elastic twist generated by variations in the tip parameters strongly correlated with rotor performance and loads, but the magnitude of advancing blade elastic twist did not. In addition, fixed system vibratory loads and rotor track for potential conformable rotor candidates appears very sensitive to parametric rotor changes.

Posterior stabilized versus cruciate retaining total knee arthroplasty designs: conformity affects the performance reliability of the design over the patient population.

PubMed

Ardestani, Marzieh M; Moazen, Mehran; Maniei, Ehsan; Jin, Zhongmin

2015-04-01

Commercially available fixed bearing knee prostheses are mainly divided into two groups: posterior stabilized (PS) versus cruciate retaining (CR). Despite the widespread comparative studies, the debate continues regarding the superiority of one type over the other. This study used a combined finite element (FE) simulation and principal component analysis (PCA) to evaluate "reliability" and "sensitivity" of two PS designs versus two CR designs over a patient population. Four fixed bearing implants were chosen: PFC (DePuy), PFC Sigma (DePuy), NexGen (Zimmer) and Genesis II (Smith & Nephew). Using PCA, a large probabilistic knee joint motion and loading database was generated based on the available experimental data from literature. The probabilistic knee joint data were applied to each implant in a FE simulation to calculate the potential envelopes of kinematics (i.e. anterior-posterior [AP] displacement and internal-external [IE] rotation) and contact mechanics. The performance envelopes were considered as an indicator of performance reliability. For each implant, PCA was used to highlight how much the implant performance was influenced by changes in each input parameter (sensitivity). Results showed that (1) conformity directly affected the reliability of the knee implant over a patient population such that lesser conformity designs (PS or CR), had higher kinematic variability and were more influenced by AP force and IE torque, (2) contact reliability did not differ noticeably among different designs and (3) CR or PS designs affected the relative rank of critical factors that influenced the reliability of each design. Such investigations enlighten the underlying biomechanics of various implant designs and can be utilized to estimate the potential performance of an implant design over a patient population. Copyright © 2015 IPEM. Published by Elsevier Ltd. All rights reserved.

Conceptual Launch Vehicle and Spacecraft Design for Risk Assessment

NASA Technical Reports Server (NTRS)

Motiwala, Samira A.; Mathias, Donovan L.; Mattenberger, Christopher J.

2014-01-01

One of the most challenging aspects of developing human space launch and exploration systems is minimizing and mitigating the many potential risk factors to ensure the safest possible design while also meeting the required cost, weight, and performance criteria. In order to accomplish this, effective risk analyses and trade studies are needed to identify key risk drivers, dependencies, and sensitivities as the design evolves. The Engineering Risk Assessment (ERA) team at NASA Ames Research Center (ARC) develops advanced risk analysis approaches, models, and tools to provide such meaningful risk and reliability data throughout vehicle development. The goal of the project presented in this memorandum is to design a generic launch 7 vehicle and spacecraft architecture that can be used to develop and demonstrate these new risk analysis techniques without relying on other proprietary or sensitive vehicle designs. To accomplish this, initial spacecraft and launch vehicle (LV) designs were established using historical sizing relationships for a mission delivering four crewmembers and equipment to the International Space Station (ISS). Mass-estimating relationships (MERs) were used to size the crew capsule and launch vehicle, and a combination of optimization techniques and iterative design processes were employed to determine a possible two-stage-to-orbit (TSTO) launch trajectory into a 350-kilometer orbit. Primary subsystems were also designed for the crewed capsule architecture, based on a 24-hour on-orbit mission with a 7-day contingency. Safety analysis was also performed to identify major risks to crew survivability and assess the system's overall reliability. These procedures and analyses validate that the architecture's basic design and performance are reasonable to be used for risk trade studies. While the vehicle designs presented are not intended to represent a viable architecture, they will provide a valuable initial platform for developing and demonstrating innovative risk assessment capabilities.

Coordinate Axes and Mental Rotation Tasks: A Solomon Four Group Design.

ERIC Educational Resources Information Center

Branoff, Theodore J.

1999-01-01

Studies the effectiveness of adding coordinate axes to mental rotations tasks. Assesses the effect of the coordinate axes, the effect of pretest sensitization, and interaction between the pretest and posttest conditions. (Author/CCM)

Study of thermal effects on nickel-cadmium batteries

NASA Technical Reports Server (NTRS)

Foley, R. T.; Webster, W. H.

1967-01-01

Isothermal continuous flow calorimeter is designed to test a nickel-cadmium battery under numerous orbital conditions. This sensitive calorimeter collects cell data such as oxygen pressure and rate of heat generation, and calculates changes in enthalpy.

Statistical sensitivity analysis of a simple nuclear waste repository model

NASA Astrophysics Data System (ADS)

Ronen, Y.; Lucius, J. L.; Blow, E. M.

1980-06-01

A preliminary step in a comprehensive sensitivity analysis of the modeling of a nuclear waste repository. The purpose of the complete analysis is to determine which modeling parameters and physical data are most important in determining key design performance criteria and then to obtain the uncertainty in the design for safety considerations. The theory for a statistical screening design methodology is developed for later use in the overall program. The theory was applied to the test case of determining the relative importance of the sensitivity of near field temperature distribution in a single level salt repository to modeling parameters. The exact values of the sensitivities to these physical and modeling parameters were then obtained using direct methods of recalculation. The sensitivity coefficients found to be important for the sample problem were thermal loading, distance between the spent fuel canisters and their radius. Other important parameters were those related to salt properties at a point of interest in the repository.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Lijuan; Gonder, Jeff; Burton, Evan

This study evaluates the costs and benefits associated with the use of a stationary-wireless- power-transfer-enabled plug-in hybrid electric bus and determines the cost effectiveness relative to a conventional bus and a hybrid electric bus. A sensitivity sweep was performed over many different battery sizes, charging power levels, and number/location of bus stop charging stations. The net present cost was calculated for each vehicle design and provided the basis for design evaluation. In all cases, given the assumed economic conditions, the conventional bus achieved the lowest net present cost while the optimal plug-in hybrid electric bus scenario beat out the hybridmore » electric comparison scenario. The study also performed parameter sensitivity analysis under favorable and high unfavorable market penetration assumptions. The analysis identifies fuel saving opportunities with plug-in hybrid electric bus scenarios at cumulative net present costs not too dissimilar from those for conventional buses.« less

Solvatochromic and Fluorogenic Dyes as Environment-Sensitive Probes: Design and Biological Applications.

PubMed

Klymchenko, Andrey S

2017-02-21

Fluorescent environment-sensitive probes are specially designed dyes that change their fluorescence intensity (fluorogenic dyes) or color (e.g., solvatochromic dyes) in response to change in their microenvironment polarity, viscosity, and molecular order. The studies of the past decade, including those of our group, have shown that these molecules become universal tools in fluorescence sensing and imaging. In fact, any biomolecular interaction or change in biomolecular organization results in modification of the local microenvironment, which can be directly monitored by these types of probes. In this Account, the main examples of environment-sensitive probes are summarized according to their design concepts. Solvatochromic dyes constitute a large class of environment-sensitive probes which change their color in response to polarity. Generally, they are push-pull dyes undergoing intramolecular charge transfer. Emission of their highly polarized excited state shifts to the red in more polar solvents. Excited-state intramolecular proton transfer is the second key concept to design efficient solvatochromic dyes, which respond to the microenvironment by changing relative intensity of the two emissive tautomeric forms. Due to their sensitivity to polarity and hydration, solvatochromic dyes have been successfully applied to biological membranes for studying lipid domains (rafts), apoptosis and endocytosis. As fluorescent labels, solvatochromic dyes can detect practically any type of biomolecular interactions, involving proteins, nucleic acids and biomembranes, because the binding event excludes local water molecules from the interaction site. On the other hand, fluorogenic probes usually exploit intramolecular rotation (conformation change) as a design concept, with molecular rotors being main representatives. These probes were particularly efficient for imaging viscosity and lipid order in biomembranes as well as to light up biomolecular targets, such as antibodies, aptamers and receptors. The emerging concepts to achieve fluorogenic response to the microenvironment include ground-state isomerization, aggregation-caused quenching, and aggregation-induced emission. The ground-state isomerization exploits, for instance, polarity-dependent spiro-lactone formation in silica-rhodamines. The aggregation-caused quenching uses disruption of the self-quenched dimers and nanoassemblies of dyes in less polar environments of lipid membranes and biomolecules. The aggregation-induced emission couples target recognition with formation of highly fluorescent dye aggregates. Overall, solvatochromic and fluorogenic probes enable background-free bioimaging in wash-free conditions as well as quantitative analysis when combined with advanced microscopy, such as fluorescence lifetime (FLIM) and ratiometric imaging. Further development of fluorescent environment-sensitive probes should address some remaining problems: (i) improving their optical properties, especially brightness, photostability, and far-red to near-infrared operating range; (ii) minimizing nonspecific interactions of the probes in biological systems; (iii) their adaptation for advanced microscopies, notably for superresolution and in vivo imaging.

Detection of HbsAg and hATIII genetically modified goats (Caprahircus) by loop-mediated isothermal amplification.

PubMed

Tao, Chenyu; Zhang, Qingde; Zhai, Shanli; Liu, Bang

2013-11-01

In this study, sensitive and rapid detection systems were designed using a loop-mediated isothermal amplification (LAMP) method to detect the genetically modified goats. A set of 4 primers were designed for each exogenous nucleic acids HBsAg and hATIII. The DNA samples were first amplified with the outer and inner primers and released a single-stranded DNA,of which both ends were stem-loop structure. Then one inner primer hybridized with the loop, and initiated displacement synthesis in less than 1 h. The result could be visualized by both agarose gel electrophoresis and unaided eyes directly after adding SYBR GREEN 1. The detection limit of LAMP was ten copies of target molecules, indicating that LAMP was tenfold more sensitive than the classical PCR. Furthermore, all the samples of genetically modified goats were tested positively by LAMP, and the results demonstrated that the LAMP was a rapid and sensitive method for detecting the genetically modified organism.

Efficient sensitivity analysis and optimization of a helicopter rotor

NASA Technical Reports Server (NTRS)

Lim, Joon W.; Chopra, Inderjit

1989-01-01

Aeroelastic optimization of a system essentially consists of the determination of the optimum values of design variables which minimize the objective function and satisfy certain aeroelastic and geometric constraints. The process of aeroelastic optimization analysis is illustrated. To carry out aeroelastic optimization effectively, one needs a reliable analysis procedure to determine steady response and stability of a rotor system in forward flight. The rotor dynamic analysis used in the present study developed inhouse at the University of Maryland is based on finite elements in space and time. The analysis consists of two major phases: vehicle trim and rotor steady response (coupled trim analysis), and aeroelastic stability of the blade. For a reduction of helicopter vibration, the optimization process requires the sensitivity derivatives of the objective function and aeroelastic stability constraints. For this, the derivatives of steady response, hub loads and blade stability roots are calculated using a direct analytical approach. An automated optimization procedure is developed by coupling the rotor dynamic analysis, design sensitivity analysis and constrained optimization code CONMIN.

Epidemiology and Clinical Research Design, Part 2: Principles

PubMed Central

Manja, Veena; Lakshminrusimha, Satyan

2015-01-01

This is the third article covering core knowledge in scholarly activities for neonatal physicians. In this article, we discuss various principles of epidemiology and clinical research design. A basic knowledge of these principles is necessary for conducting clinical research and for proper interpretation of studies. This article reviews bias and confounding, causation, incidence and prevalence, decision analysis, cost-effectiveness, sensitivity analysis, and measurement. PMID:26236171

A practical approach to the sensitivity analysis for kinetic Monte Carlo simulation of heterogeneous catalysis

DOE PAGES

Hoffmann, Max J.; Engelmann, Felix; Matera, Sebastian

2017-01-31

Lattice kinetic Monte Carlo simulations have become a vital tool for predictive quality atomistic understanding of complex surface chemical reaction kinetics over a wide range of reaction conditions. In order to expand their practical value in terms of giving guidelines for atomic level design of catalytic systems, it is very desirable to readily evaluate a sensitivity analysis for a given model. The result of such a sensitivity analysis quantitatively expresses the dependency of the turnover frequency, being the main output variable, on the rate constants entering the model. In the past the application of sensitivity analysis, such as Degree ofmore » Rate Control, has been hampered by its exuberant computational effort required to accurately sample numerical derivatives of a property that is obtained from a stochastic simulation method. Here in this study we present an efficient and robust three stage approach that is capable of reliably evaluating the sensitivity measures for stiff microkinetic models as we demonstrate using CO oxidation on RuO 2(110) as a prototypical reaction. In a first step, we utilize the Fisher Information Matrix for filtering out elementary processes which only yield negligible sensitivity. Then we employ an estimator based on linear response theory for calculating the sensitivity measure for non-critical conditions which covers the majority of cases. Finally we adopt a method for sampling coupled finite differences for evaluating the sensitivity measure of lattice based models. This allows efficient evaluation even in critical regions near a second order phase transition that are hitherto difficult to control. The combined approach leads to significant computational savings over straightforward numerical derivatives and should aid in accelerating the nano scale design of heterogeneous catalysts.« less

A practical approach to the sensitivity analysis for kinetic Monte Carlo simulation of heterogeneous catalysis.

PubMed

Hoffmann, Max J; Engelmann, Felix; Matera, Sebastian

2017-01-28

Lattice kinetic Monte Carlo simulations have become a vital tool for predictive quality atomistic understanding of complex surface chemical reaction kinetics over a wide range of reaction conditions. In order to expand their practical value in terms of giving guidelines for the atomic level design of catalytic systems, it is very desirable to readily evaluate a sensitivity analysis for a given model. The result of such a sensitivity analysis quantitatively expresses the dependency of the turnover frequency, being the main output variable, on the rate constants entering the model. In the past, the application of sensitivity analysis, such as degree of rate control, has been hampered by its exuberant computational effort required to accurately sample numerical derivatives of a property that is obtained from a stochastic simulation method. In this study, we present an efficient and robust three-stage approach that is capable of reliably evaluating the sensitivity measures for stiff microkinetic models as we demonstrate using the CO oxidation on RuO 2 (110) as a prototypical reaction. In the first step, we utilize the Fisher information matrix for filtering out elementary processes which only yield negligible sensitivity. Then we employ an estimator based on the linear response theory for calculating the sensitivity measure for non-critical conditions which covers the majority of cases. Finally, we adapt a method for sampling coupled finite differences for evaluating the sensitivity measure for lattice based models. This allows for an efficient evaluation even in critical regions near a second order phase transition that are hitherto difficult to control. The combined approach leads to significant computational savings over straightforward numerical derivatives and should aid in accelerating the nano-scale design of heterogeneous catalysts.

A practical approach to the sensitivity analysis for kinetic Monte Carlo simulation of heterogeneous catalysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoffmann, Max J.; Engelmann, Felix; Matera, Sebastian

Lattice kinetic Monte Carlo simulations have become a vital tool for predictive quality atomistic understanding of complex surface chemical reaction kinetics over a wide range of reaction conditions. In order to expand their practical value in terms of giving guidelines for atomic level design of catalytic systems, it is very desirable to readily evaluate a sensitivity analysis for a given model. The result of such a sensitivity analysis quantitatively expresses the dependency of the turnover frequency, being the main output variable, on the rate constants entering the model. In the past the application of sensitivity analysis, such as Degree ofmore » Rate Control, has been hampered by its exuberant computational effort required to accurately sample numerical derivatives of a property that is obtained from a stochastic simulation method. Here in this study we present an efficient and robust three stage approach that is capable of reliably evaluating the sensitivity measures for stiff microkinetic models as we demonstrate using CO oxidation on RuO 2(110) as a prototypical reaction. In a first step, we utilize the Fisher Information Matrix for filtering out elementary processes which only yield negligible sensitivity. Then we employ an estimator based on linear response theory for calculating the sensitivity measure for non-critical conditions which covers the majority of cases. Finally we adopt a method for sampling coupled finite differences for evaluating the sensitivity measure of lattice based models. This allows efficient evaluation even in critical regions near a second order phase transition that are hitherto difficult to control. The combined approach leads to significant computational savings over straightforward numerical derivatives and should aid in accelerating the nano scale design of heterogeneous catalysts.« less

A practical approach to the sensitivity analysis for kinetic Monte Carlo simulation of heterogeneous catalysis

NASA Astrophysics Data System (ADS)

Hoffmann, Max J.; Engelmann, Felix; Matera, Sebastian

2017-01-01

Lattice kinetic Monte Carlo simulations have become a vital tool for predictive quality atomistic understanding of complex surface chemical reaction kinetics over a wide range of reaction conditions. In order to expand their practical value in terms of giving guidelines for the atomic level design of catalytic systems, it is very desirable to readily evaluate a sensitivity analysis for a given model. The result of such a sensitivity analysis quantitatively expresses the dependency of the turnover frequency, being the main output variable, on the rate constants entering the model. In the past, the application of sensitivity analysis, such as degree of rate control, has been hampered by its exuberant computational effort required to accurately sample numerical derivatives of a property that is obtained from a stochastic simulation method. In this study, we present an efficient and robust three-stage approach that is capable of reliably evaluating the sensitivity measures for stiff microkinetic models as we demonstrate using the CO oxidation on RuO2(110) as a prototypical reaction. In the first step, we utilize the Fisher information matrix for filtering out elementary processes which only yield negligible sensitivity. Then we employ an estimator based on the linear response theory for calculating the sensitivity measure for non-critical conditions which covers the majority of cases. Finally, we adapt a method for sampling coupled finite differences for evaluating the sensitivity measure for lattice based models. This allows for an efficient evaluation even in critical regions near a second order phase transition that are hitherto difficult to control. The combined approach leads to significant computational savings over straightforward numerical derivatives and should aid in accelerating the nano-scale design of heterogeneous catalysts.

Compact Highly Sensitive Multi-species Airborne Mid-IR Spectrometer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Richter, Dirk; Weibring, P.; Walega, J.

2015-02-01

We report on the development and airborne field deployment of a mid-IR laser based spectrometer. The instrument was configured for the simultaneous in-situ detection of formaldehyde (CH2O) and ethane (C2H6). Numerous mechanical, optical, electronic, and software improvements over a previous instrument design resulted in reliable highly sensitive airborne operation with long stability times yielding 90% airborne measurement coverage during the recent air quality study over the Colorado front range, FRAPPÉ 2014. Airborne detection sensitivities of ~ 15 pptv (C2H6) and ~40 pptv (CH2O) were generally obtained for 1 s of averaging for simultaneous detection.

The Perils of Ignoring Design Effects in Experimental Studies: Lessons from a Mammography Screening Trial

PubMed Central

Glenn, Beth A.; Bastani, Roshan; Maxwell, Annette E.

2013-01-01

Objective Threats to external validity including pretest sensitization and the interaction of selection and an intervention are frequently overlooked by researchers despite their potential to significantly influence study outcomes. The purpose of this investigation was to conduct secondary data analyses to assess the presence of external validity threats in the setting of a randomized trial designed to promote mammography use in a high risk sample of women. Design During the trial, recruitment and intervention implementation took place in three cohorts (with different ethnic composition), utilizing two different designs (pretest-posttest control group design; posttest only control group design). Results Results reveal that the intervention produced different outcomes across cohorts, dependent upon the research design used and the characteristics of the sample. Conclusion These results illustrate the importance of weighing the pros and cons of potential research designs before making a selection and attending more closely to issues of external validity. PMID:23289517

Ergonomics for the inclusion of older workers in the knowledge workforce and a guidance tool for designers.

PubMed

Gonzalez, I; Morer, P

2016-03-01

The ageing of the population and the inverted population pyramid is bringing important changes to society as a whole. These changes are associated with the inclusion of an older workforce in knowledge work and the challenge they represent in adapting the work environment accordingly. In order to approach a more universal design of the work environment, industrial designers need support from user-sensitive inclusive design studies. While there are plenty of guidelines and tools containing relevant information, there is a need to develop more appropriate tools for Industrial Designers that cover the initial phase of the design process. This study provides a review of the available tools and guidelines and proposes a theoretical framework intended for developing a design guidance tool for inclusive workstation design. Copyright © 2015 Elsevier Ltd and The Ergonomics Society. All rights reserved.

A traits-based approach for prioritizing species for monitoring and surrogacy selection

DOE PAGES

Pracheil, Brenda M.; McManamay, Ryan A.; Bevelhimer, Mark S.; ...

2016-11-28

The bar for justifying the use of vertebrate animals for study is being increasingly raised, thus requiring increased rigor for species selection and study design. Although we have power analyses to provide quantitative backing for the numbers of organisms used, quantitative backing for selection of study species is not frequently employed. This can be especially important when measuring the impacts of ecosystem alteration, when study species must be chosen that are both sensitive to the alteration and of sufficient abundance for study. Just as important is providing justification for designation of surrogate species for study, especially when the species ofmore » interest is rare or of conservation concern and selection of an appropriate surrogate can have legal implications. In this study, we use a combination of GIS, a fish traits database and multivariate statistical analyses to quantitatively prioritize species for study and to determine potential study surrogate species. We provide two case studies to illustrate our quantitative, traits-based approach for designating study species and surrogate species. In the first case study, we select broadly representative fish species to understand the effects of turbine passage on adult fishes based on traits that suggest sensitivity to turbine passage. In our second case study, we present a framework for selecting a surrogate species for an endangered species. Lastly, we suggest that our traits-based framework can provide quantitative backing and added justification to selection of study species while expanding the inference space of study results.« less

A traits-based approach for prioritizing species for monitoring and surrogacy selection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pracheil, Brenda M.; McManamay, Ryan A.; Bevelhimer, Mark S.

The bar for justifying the use of vertebrate animals for study is being increasingly raised, thus requiring increased rigor for species selection and study design. Although we have power analyses to provide quantitative backing for the numbers of organisms used, quantitative backing for selection of study species is not frequently employed. This can be especially important when measuring the impacts of ecosystem alteration, when study species must be chosen that are both sensitive to the alteration and of sufficient abundance for study. Just as important is providing justification for designation of surrogate species for study, especially when the species ofmore » interest is rare or of conservation concern and selection of an appropriate surrogate can have legal implications. In this study, we use a combination of GIS, a fish traits database and multivariate statistical analyses to quantitatively prioritize species for study and to determine potential study surrogate species. We provide two case studies to illustrate our quantitative, traits-based approach for designating study species and surrogate species. In the first case study, we select broadly representative fish species to understand the effects of turbine passage on adult fishes based on traits that suggest sensitivity to turbine passage. In our second case study, we present a framework for selecting a surrogate species for an endangered species. Lastly, we suggest that our traits-based framework can provide quantitative backing and added justification to selection of study species while expanding the inference space of study results.« less

Spin-exchange relaxation-free magnetometer with nearly parallel pump and probe beams

DOE PAGES

Karaulanov, Todor; Savukov, Igor; Kim, Young Jin

2016-03-22

We constructed a spin-exchange relaxation-free (SERF) magnetometer with a small angle between the pump and probe beams facilitating a multi-channel design with a flat pancake cell. This configuration provides almost complete overlap of the beams in the cell, and prevents the pump beam from entering the probe detection channel. By coupling the lasers in multi-mode fibers, without an optical isolator or field modulation, we demonstrate a sensitivity of 10 fTmore » $$/\\sqrt{\\text{Hz}}$$ for frequencies between 10 Hz and 100 Hz. In addition to the experimental study of sensitivity, we present a theoretical analysis of SERF magnetometer response to magnetic fields for small-angle and parallel-beam configurations, and show that at optimal DC offset fields the magnetometer response is comparable to that in the orthogonal-beam configuration. Based on the analysis, we also derive fundamental and probe-limited sensitivities for the arbitrary non-orthogonal geometry. The expected practical and fundamental sensitivities are of the same order as those in the orthogonal geometry. As a result, we anticipate that our design will be useful for magnetoencephalography (MEG) and magnetocardiography (MCG) applications.« less

Design and fabrication of a differential scanning nanocalorimeter

DOE PAGES

Zuo, Lei; Chen, Xiaoming; Yu, Shifeng; ...

2016-12-19

This paper describes the design, fabrication, and characterization of a differential scanning nanocalorimeter that significantly reduces the sample volume to microliters and can potentially improve the temperature sensitivity to 10 µK. The nanocalorimeter consists of a polymeric freestanding membrane, four high-sensitive low-noise thermistors based on silicon carbide (SiC), and a platinum heater and temperature sensor. With the integrated heater and sensors, temperature scanning and power compensation can be achieved for calorimetric measurement. Temperature sensing SiC film was prepared by using sintered SiC target and DC magnetron sputtering under different gas pressures and sputtering power. The SiC sensing material is characterizedmore » through the measurement of current–voltage curves and noise levels. The thermal performance of a fabricated nanocalorimeter is studied in simulation and experiment. The experiment results show the device has excellent thermal isolation to hold thermal energy. As a result, the noise test together with the simulation show the device is promising for micro 10 µK temperature sensitivity and nanowatt resolution which will lead to low-volume ultra-sensitive nanocalorimetry for biological processes, such as protein folding and ligand binding.« less

Position-sensitive, fast ionization chambers

NASA Astrophysics Data System (ADS)

Lai, J.; Afanasieva, L.; Blackmon, J. C.; Deibel, C. M.; Gardiner, H. E.; Lauer, A.; Linhardt, L. E.; Macon, K. T.; Rasco, B. C.; Williams, C.; Santiago-Gonzalez, D.; Kuvin, S. A.; Almaraz-Calderon, S.; Baby, L. T.; Baker, J.; Belarge, J.; Wiedenhöver, I.; Need, E.; Avila, M. L.; Back, B. B.; DiGiovine, B.; Hoffman, C. R.

2018-05-01

A high-count-rate ionization chamber design with position-sensitivity has been developed and deployed at several accelerator facilities. Counting rates of ≥ 500 kHz with good Z-separation (up to 5% energy resolution) for particle identification have been demonstrated in a series of commissioning experiments. A position-sensitive capability, with a resolution of 3 mm, has been implemented for the first time to record position information and suppress pileup. The design and performance of the detectors are described.

Adjoint Sensitivity Computations for an Embedded-Boundary Cartesian Mesh Method and CAD Geometry

NASA Technical Reports Server (NTRS)

Nemec, Marian; Aftosmis,Michael J.

2006-01-01

Cartesian-mesh methods are perhaps the most promising approach for addressing the issues of flow solution automation for aerodynamic design problems. In these methods, the discretization of the wetted surface is decoupled from that of the volume mesh. This not only enables fast and robust mesh generation for geometry of arbitrary complexity, but also facilitates access to geometry modeling and manipulation using parametric Computer-Aided Design (CAD) tools. Our goal is to combine the automation capabilities of Cartesian methods with an eficient computation of design sensitivities. We address this issue using the adjoint method, where the computational cost of the design sensitivities, or objective function gradients, is esseutially indepeudent of the number of design variables. In previous work, we presented an accurate and efficient algorithm for the solution of the adjoint Euler equations discretized on Cartesian meshes with embedded, cut-cell boundaries. Novel aspects of the algorithm included the computation of surface shape sensitivities for triangulations based on parametric-CAD models and the linearization of the coupling between the surface triangulation and the cut-cells. The objective of the present work is to extend our adjoint formulation to problems involving general shape changes. Central to this development is the computation of volume-mesh sensitivities to obtain a reliable approximation of the objective finction gradient. Motivated by the success of mesh-perturbation schemes commonly used in body-fitted unstructured formulations, we propose an approach based on a local linearization of a mesh-perturbation scheme similar to the spring analogy. This approach circumvents most of the difficulties that arise due to non-smooth changes in the cut-cell layer as the boundary shape evolves and provides a consistent approximation tot he exact gradient of the discretized abjective function. A detailed gradient accurace study is presented to verify our approach. Thereafter, we focus on a shape optimization problem for an Apollo-like reentry capsule. The optimization seeks to enhance the lift-to-drag ratio of the capsule by modifyjing the shape of its heat-shield in conjunction with a center-of-gravity (c.g.) offset. This multipoint and multi-objective optimization problem is used to demonstrate the overall effectiveness of the Cartesian adjoint method for addressing the issues of complex aerodynamic design. This abstract presents only a brief outline of the numerical method and results; full details will be given in the final paper.

Structural optimization: Status and promise

NASA Astrophysics Data System (ADS)

Kamat, Manohar P.

Chapters contained in this book include fundamental concepts of optimum design, mathematical programming methods for constrained optimization, function approximations, approximate reanalysis methods, dual mathematical programming methods for constrained optimization, a generalized optimality criteria method, and a tutorial and survey of multicriteria optimization in engineering. Also included are chapters on the compromise decision support problem and the adaptive linear programming algorithm, sensitivity analyses of discrete and distributed systems, the design sensitivity analysis of nonlinear structures, optimization by decomposition, mixed elements in shape sensitivity analysis of structures based on local criteria, and optimization of stiffened cylindrical shells subjected to destabilizing loads. Other chapters are on applications to fixed-wing aircraft and spacecraft, integrated optimum structural and control design, modeling concurrency in the design of composite structures, and tools for structural optimization. (No individual items are abstracted in this volume)

Predicting chemically-induced skin reactions. Part II: QSAR models of skin permeability and the relationships between skin permeability and skin sensitization

PubMed Central

Alves, Vinicius M.; Muratov, Eugene; Fourches, Denis; Strickland, Judy; Kleinstreuer, Nicole; Andrade, Carolina H.; Tropsha, Alexander

2015-01-01

Skin permeability is widely considered to be mechanistically implicated in chemically-induced skin sensitization. Although many chemicals have been identified as skin sensitizers, there have been very few reports analyzing the relationships between molecular structure and skin permeability of sensitizers and non-sensitizers. The goals of this study were to: (i) compile, curate, and integrate the largest publicly available dataset of chemicals studied for their skin permeability; (ii) develop and rigorously validate QSAR models to predict skin permeability; and (iii) explore the complex relationships between skin sensitization and skin permeability. Based on the largest publicly available dataset compiled in this study, we found no overall correlation between skin permeability and skin sensitization. In addition, cross-species correlation coefficient between human and rodent permeability data was found to be as low as R2=0.44. Human skin permeability models based on the random forest method have been developed and validated using OECD-compliant QSAR modeling workflow. Their external accuracy was high (Q2ext = 0.73 for 63% of external compounds inside the applicability domain). The extended analysis using both experimentally-measured and QSAR-imputed data still confirmed the absence of any overall concordance between skin permeability and skin sensitization. This observation suggests that chemical modifications that affect skin permeability should not be presumed a priori to modulate the sensitization potential of chemicals. The models reported herein as well as those developed in the companion paper on skin sensitization suggest that it may be possible to rationally design compounds with the desired high skin permeability but low sensitization potential. PMID:25560673

Use of experimental design in the investigation of stir bar sorptive extraction followed by ultra-high-performance liquid chromatography-tandem mass spectrometry for the analysis of explosives in water samples.

PubMed

Schramm, Sébastien; Vailhen, Dominique; Bridoux, Maxime Cyril

2016-02-12

A method for the sensitive quantification of trace amounts of organic explosives in water samples was developed by using stir bar sorptive extraction (SBSE) followed by liquid desorption and ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The proposed method was developed and optimized using a statistical design of experiment approach. Use of experimental designs allowed a complete study of 10 factors and 8 analytes including nitro-aromatics, amino-nitro-aromatics and nitric esters. The liquid desorption study was performed using a full factorial experimental design followed by a kinetic study. Four different variables were tested here: the liquid desorption mode (stirring or sonication), the chemical nature of the stir bar (PDMS or PDMS-PEG), the composition of the liquid desorption phase and finally, the volume of solvent used for the liquid desorption. On the other hand, the SBSE extraction study was performed using a Doehlert design. SBSE extraction conditions such as extraction time profiles, sample volume, modifier addition, and acetic acid addition were examined. After optimization of the experimental parameters, sensitivity was improved by a factor 5-30, depending on the compound studied, due to the enrichment factors reached using the SBSE method. Limits of detection were in the ng/L level for all analytes studied. Reproducibility of the extraction with different stir bars was close to the reproducibility of the analytical method (RSD between 4 and 16%). Extractions in various water sample matrices (spring, mineral and underground water) have shown similar enrichment compared to ultrapure water, revealing very low matrix effects. Copyright © 2016 Elsevier B.V. All rights reserved.

Ozone Response to Aircraft Emissions: Sensitivity Studies with Two-dimensional Models

NASA Technical Reports Server (NTRS)

Ko, Malcolm K. W.; Weisenstein, Debra; Jackman, Charles H.; Douglass, Anne R.; Bureske, K.; Weubbles, Donald J.; Kinnison, Douglas E.; Brasseur, G.; Pyle, J.; Jones, Anna

1992-01-01

Our first intercomparison/assessment of the effects of a proposed high-speed civil transport (HSCT) fleet on the stratosphere is presented. These model calculations should be considered more as sensitivity studies, primarily designed to serve the following purposes: (1) to allow for intercomparison of model predictions; (2) to focus on the range of fleet operations and engine specifications giving minimal environmental impact; and (3) to provide the basis for future assessment studies. The basic scenarios were chosen to be as realistic as possible, using the information available on anticipated developments in technology. They are not to be interpreted as a commitment or goal for environmental acceptability.

Active and passive shielding design optimization and technical solutions for deep sensitivity hard x-ray focusing telescopes

NASA Astrophysics Data System (ADS)

Malaguti, G.; Pareschi, G.; Ferrando, P.; Caroli, E.; Di Cocco, G.; Foschini, L.; Basso, S.; Del Sordo, S.; Fiore, F.; Bonati, A.; Lesci, G.; Poulsen, J. M.; Monzani, F.; Stevoli, A.; Negri, B.

2005-08-01

The 10-100 keV region of the electromagnetic spectrum contains the potential for a dramatic improvement in our understanding of a number of key problems in high energy astrophysics. A deep inspection of the universe in this band is on the other hand still lacking because of the demanding sensitivity (fraction of μCrab in the 20-40 keV for 1 Ms integration time) and imaging (≈ 15" angular resolution) requirements. The mission ideas currently being proposed are based on long focal length, grazing incidence, multi-layer optics, coupled with focal plane detectors with few hundreds μm spatial resolution capability. The required large focal lengths, ranging between 8 and 50 m, can be realized by means of extendable optical benches (as foreseen e.g. for the HEXITSAT, NEXT and NuSTAR missions) or formation flight scenarios (e.g. Simbol-X and XEUS). While the final telescope design will require a detailed trade-off analysis between all the relevant parameters (focal length, plate scale value, angular resolution, field of view, detector size, and sensitivity degradation due to detector dead area and telescope vignetting), extreme attention must be dedicated to the background minimization. In this respect, key issues are represented by the passive baffling system, which in case of large focal lengths requires particular design assessments, and by the active/passive shielding geometries and materials. In this work, the result of a study of the expected background for a hard X-ray telescope is presented, and its implication on the required sensitivity, together with the possible implementation design concepts for active and passive shielding in the framework of future satellite missions, are discussed.

The Diagnostic Performance of Stool DNA Testing for Colorectal Cancer: A Systematic Review and Meta-Analysis.

PubMed

Zhai, Rong-Lin; Xu, Fei; Zhang, Pei; Zhang, Wan-Li; Wang, Hui; Wang, Ji-Liang; Cai, Kai-Lin; Long, Yue-Ping; Lu, Xiao-Ming; Tao, Kai-Xiong; Wang, Guo-Bin

2016-02-01

This meta-analysis was designed to evaluate the diagnostic performance of stool DNA testing for colorectal cancer (CRC) and compare the performance between single-gene and multiple-gene tests.MEDLINE, Cochrane, EMBASE databases were searched using keywords colorectal cancers, stool/fecal, sensitivity, specificity, DNA, and screening. Sensitivity analysis, quality assessments, and performance bias were performed for the included studies.Fifty-three studies were included in the analysis with a total sample size of 7524 patients. The studies were heterogeneous with regard to the genes being analyzed for fecal genetic biomarkers of CRC, as well as the laboratory methods being used for each assay. The sensitivity of the different assays ranged from 2% to 100% and the specificity ranged from 81% to 100%. The meta-analysis found that the pooled sensitivities for single- and multigene assays were 48.0% and 77.8%, respectively, while the pooled specificities were 97.0% and 92.7%. Receiver operator curves and diagnostic odds ratios showed no significant difference between both tests with regard to sensitivity or specificity.This meta-analysis revealed that using assays that evaluated multiple genes compared with single-gene assays did not increase the sensitivity or specificity of stool DNA testing in detecting CRC.

Designing robots for care: care centered value-sensitive design.

PubMed

van Wynsberghe, Aimee

2013-06-01

The prospective robots in healthcare intended to be included within the conclave of the nurse-patient relationship--what I refer to as care robots--require rigorous ethical reflection to ensure their design and introduction do not impede the promotion of values and the dignity of patients at such a vulnerable and sensitive time in their lives. The ethical evaluation of care robots requires insight into the values at stake in the healthcare tradition. What's more, given the stage of their development and lack of standards provided by the International Organization for Standardization to guide their development, ethics ought to be included into the design process of such robots. The manner in which this may be accomplished, as presented here, uses the blueprint of the Value-sensitive design approach as a means for creating a framework tailored to care contexts. Using care values as the foundational values to be integrated into a technology and using the elements in care, from the care ethics perspective, as the normative criteria, the resulting approach may be referred to as care centered value-sensitive design. The framework proposed here allows for the ethical evaluation of care robots both retrospectively and prospectively. By evaluating care robots in this way, we may ultimately ask what kind of care we, as a society, want to provide in the future.

Nitrogen fertilization effects on sorghum forage yield and quality

USDA-ARS?s Scientific Manuscript database

The study objective was to determine the effect of nitrogen fertilization on yield and quality of photoperiod sensitive (PS) and non-PS forage sorghum, sorghum-sudangrass, and sudangrass compared to corn. This study was a randomized complete block design with treatments arranged in a 4 x 8 factorial...

Faith-Based Mental Health Interventions with African Americans: A Review

ERIC Educational Resources Information Center

Hays, Krystal; Aranda, Maria P.

2016-01-01

Faith-based interventions have emerged culturally sensitive way to address mental health issues among African Americans. This systematic review explores the scope and efficacy of faith-based mental health intervention outcomes among African Americans. Extracted data included the study population, setting, study design, intervention, adaptations,…

Test, episode, and programme sensitivities of screening for colorectal cancer as a public health policy in Finland: experimental design.

PubMed

Malila, Nea; Oivanen, Tiina; Malminiemi, Outi; Hakama, Matti

2008-11-20

To report the sensitivities of the faecal occult blood test, screening episode, and screening programme for colorectal cancer and the benefits of applying a randomised design at the implementation phase of a new public health policy. Experimental design incorporated in public health evaluation using randomisation at individual level in the target population. 161 of the 431 Finnish municipalities in 2004-6. 106 000 adults randomised to screening or control arms. In total, 52 998 adults aged 60-64 in the screening arm received faecal occult blood test kits. Test, episode, and programme sensitivities estimated by the incidence method and corrected for selective attendance and overdiagnosis. The response for screening was high overall (70.8%), and significantly better in women (78.1%) than in men (63.3%). The incidence of cancer in the controls was somewhat higher in men than in women (103 v 93 per 100 000 person years), which was not true for interval cancers (42 v 49 per 100 000 person years). The sensitivity of the faecal occult blood test was 54.6%. Only a few interval cancers were detected among those with positive test results, hence the episode sensitivity of 51.3% was close to the test sensitivity. At the population level the sensitivity of the programme was 37.5%. Although relatively low, the sensitivity of screening for colorectal cancer with the faecal occult blood test in Finland was adequate. An experimental design is a prerequisite for evaluation of such a screening programme because the effectiveness of preventing deaths is likely to be small and results may otherwise remain inconclusive. Thus, screening for colorectal cancer using any primary test modality should be launched in a public health programme with randomisation of the target population at the implementation phase.

Towards Sustainable H2 Production: Rational Design of Hydrophobic Triphenylamine-based Dyes for Sensitized Ethanol Photoreforming.

PubMed

Dessì, Alessio; Monai, Matteo; Bessi, Matteo; Montini, Tiziano; Calamante, Massimo; Mordini, Alessandro; Reginato, Gianna; Trono, Cosimo; Fornasiero, Paolo; Zani, Lorenzo

2018-02-22

Donor-acceptor dyes are a well-established class of photosensitizers, used to enhance visible-light harvesting in solar cells and in direct photocatalytic reactions, such as H 2 production by photoreforming of sacrificial electron donors (SEDs). Amines-typically triethanolamine (TEOA)-are commonly employed as SEDs in such reactions. Dye-sensitized photoreforming of more sustainable, biomass-derived alcohols, on the other hand, was only recently reported by using methanol as the electron donor. In this work, several rationally designed donor-acceptor dyes were used as sensitizers in H 2 photocatalytic production, comparing the efficiency of TEOA and EtOH as SEDs. In particular, the effect of hydrophobic chains in the spacer and/or the donor unit of the dyes was systematically studied. The H 2 production rates were higher when TEOA was used as SED, whereas the activity trends depended on the SED used. The best performance was obtained with TEOA by using a sensitizer with just one bulky hydrophobic moiety, propylenedioxythiophene, placed on the spacer unit. In the case of EtOH, the best-performing sensitizers were the ones featuring a thiazolo[5,4-d]thiazole internal unit, needed for enhancing light harvesting, and carrying alkyl chains on both the donor part and the spacer unit. The results are discussed in terms of reaction mechanism, interaction with the SED, and structural/electrochemical properties of the sensitizers. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

CUBES: cassegrain U-band Brazil-ESO spectrograph

NASA Astrophysics Data System (ADS)

Barbuy, B.; Bawden Macanhan, V.; Bristow, P.; Castilho, B.; Dekker, H.; Delabre, B.; Diaz, M.; Gneiding, C.; Kerber, F.; Kuntschner, H.; La Mura, G.; Maciel, W.; Meléndez, J.; Pasquini, L.; Pereira, C. B.; Petitjean, P.; Reiss, R.; Siqueira-Mello, C.; Smiljanic, R.; Vernet, J.

2014-11-01

CUBES is a high-efficiency, medium-resolution ( R˜20,000) ground based UV (300-400 nm) spectrograph, to be installed in the cassegrain focus of one of ESO's VLT unit telescopes in 2017/18. The CUBES project is a joint venture between ESO and IAG/USP, and LNA/MCTI. CUBES will provide access to a wealth of new and relevant information for stellar as well as extragalactic sources. Main science cases include the study of beryllium and heavy elements in metal-poor stars, the direct determination of carbon, nitrogen and oxygen abundances by study of molecular bands in the UV range, as well as the study of active galactic nuclei and the quasar absorption lines. With a streamlined modern instrument design, high efficiency dispersing elements and UV-sensitive detectors, it will give a significant gain in sensitivity over existing ground based medium-high resolution spectrographs, enabling vastly increased sample sizes accessible to the astronomical community. We present here a brief overview of the project including the status, science cases and a discussion of the design options.

Advanced detectors and signal processing

NASA Technical Reports Server (NTRS)

Greve, D. W.; Rasky, P. H. L.; Kryder, M. H.

1986-01-01

Continued progress is reported toward development of a silicon on garnet technology which would allow fabrication of advanced detection and signal processing circuits on bubble memories. The first integrated detectors and propagation patterns have been designed and incorporated on a new mask set. In addition, annealing studies on spacer layers are performed. Based on those studies, a new double layer spacer is proposed which should reduce contamination of the silicon originating in the substrate. Finally, the magnetic sensitivity of uncontaminated detectors from the last lot of wafers is measured. The measured sensitivity is lower than anticipated but still higher than present magnetoresistive detectors.

Sensitivity Study of the Wall Interference Correction System (WICS) for Rectangular Tunnels

NASA Technical Reports Server (NTRS)

Walker, Eric L.; Everhart, Joel L.; Iyer, Venkit

2001-01-01

An off-line version of the Wall Interference Correction System (WICS) has been implemented for the NASA Langley National Transonic Facility. The correction capability is currently restricted to corrections for solid wall interference in the model pitch plane for Mach numbers less than 0.45 due to a limitation in tunnel calibration data. A study to assess output sensitivity to measurement uncertainty was conducted to determine standard operational procedures and guidelines to ensure data quality during the testing process. Changes to the current facility setup and design recommendations for installing the WICS code into a new facility are reported.

An experimental evaluation of a new designed apparatus (NDA) for the rapid measurement of impaired motor function in rats.

PubMed

Jarrahi, M; Sedighi Moghadam, B; Torkmandi, H

2015-08-15

Assessment of the ability of rat to balance by rotarod apparatus (ROTA) is frequently used as a measure of impaired motor system function. Most of these methods have some disadvantages, such as failing to sense motor coordination rather than endurance and as the sensitivity of the method is low, more animals are needed to obtain statistically significant results. We have designed and tested a new designed apparatus (NDA) to measure motor system function in rats. Our system consists of a glass box containing 4 beams which placed with 1cm distance between them, two electrical motors for rotating the beams, and a camera to record the movements of the rats. The RPM of the beams is adjustable digitally between 0 and 50 rounds per minute. We evaluated experimentally the capability of the NDA for the rapid measurement of impaired motor function in rats. Also we demonstrated that the sensitivity of the NDA increases by faster rotation speeds and may be more sensitive than ROTA for evaluating of impaired motor system function. Compared to a previous version of this task, our NDA provides a more efficient method to test rodents for studies of motor system function after impaired motor nervous system. In summary, our NDA will allow high efficient monitoring of rat motor system function and may be more sensitive than ROTA for evaluating of impaired motor system function in rats. Copyright © 2015 Elsevier B.V. All rights reserved.

Integrated structure/control law design by multilevel optimization

NASA Technical Reports Server (NTRS)

Gilbert, Michael G.; Schmidt, David K.

1989-01-01

A new approach to integrated structure/control law design based on multilevel optimization is presented. This new approach is applicable to aircraft and spacecraft and allows for the independent design of the structure and control law. Integration of the designs is achieved through use of an upper level coordination problem formulation within the multilevel optimization framework. The method requires the use of structure and control law design sensitivity information. A general multilevel structure/control law design problem formulation is given, and the use of Linear Quadratic Gaussian (LQG) control law design and design sensitivity methods within the formulation is illustrated. Results of three simple integrated structure/control law design examples are presented. These results show the capability of structure and control law design tradeoffs to improve controlled system performance within the multilevel approach.

Considerations of study design.

PubMed

Koretz, Ronald L

2007-12-01

Research projects attempt to answer specific questions. The particular study design that is selected will depend in large measure on the nature of the question and the time and resources available. There are 5 common categories of clinical questions; they relate to etiology, prognosis, utility of diagnostic tests, efficacy of proposed interventions, and cost of treatment in specific disease states. A number of study designs can be used. Case reports serve to memorialize unusual or novel aspects of diseases. Retrospective case series are useful for defining natural history. Case-control studies are used by epidemiologists to elucidate potential etiologies of diseases. Prospective cohort studies can be used to assess natural history or to assess potential disease etiologies. Controlled trials are designed to assess the efficacy of therapeutic interventions. Studies that define the sensitivity and specificity of diagnostic tests can be used to assess the utility of those tests. Economic analyses estimate the costs that particular diseases or therapies will require. Each of these study designs has limitations; with the exception of high-quality randomized trials, none of these study designs can establish a causative relationship between putative etiologic (or therapeutic) factors and disease (outcomes).

Piezoresistive Cantilever Performance—Part I: Analytical Model for Sensitivity

PubMed Central

Park, Sung-Jin; Doll, Joseph C.; Pruitt, Beth L.

2010-01-01

An accurate analytical model for the change in resistance of a piezoresistor is necessary for the design of silicon piezoresistive transducers. Ion implantation requires a high-temperature oxidation or annealing process to activate the dopant atoms, and this treatment results in a distorted dopant profile due to diffusion. Existing analytical models do not account for the concentration dependence of piezoresistance and are not accurate for nonuniform dopant profiles. We extend previous analytical work by introducing two nondimensional factors, namely, the efficiency and geometry factors. A practical benefit of this efficiency factor is that it separates the process parameters from the design parameters; thus, designers may address requirements for cantilever geometry and fabrication process independently. To facilitate the design process, we provide a lookup table for the efficiency factor over an extensive range of process conditions. The model was validated by comparing simulation results with the experimentally determined sensitivities of piezoresistive cantilevers. We performed 9200 TSUPREM4 simulations and fabricated 50 devices from six unique process flows; we systematically explored the design space relating process parameters and cantilever sensitivity. Our treatment focuses on piezoresistive cantilevers, but the analytical sensitivity model is extensible to other piezoresistive transducers such as membrane pressure sensors. PMID:20336183

Piezoresistive Cantilever Performance-Part I: Analytical Model for Sensitivity.

PubMed

Park, Sung-Jin; Doll, Joseph C; Pruitt, Beth L

2010-02-01

An accurate analytical model for the change in resistance of a piezoresistor is necessary for the design of silicon piezoresistive transducers. Ion implantation requires a high-temperature oxidation or annealing process to activate the dopant atoms, and this treatment results in a distorted dopant profile due to diffusion. Existing analytical models do not account for the concentration dependence of piezoresistance and are not accurate for nonuniform dopant profiles. We extend previous analytical work by introducing two nondimensional factors, namely, the efficiency and geometry factors. A practical benefit of this efficiency factor is that it separates the process parameters from the design parameters; thus, designers may address requirements for cantilever geometry and fabrication process independently. To facilitate the design process, we provide a lookup table for the efficiency factor over an extensive range of process conditions. The model was validated by comparing simulation results with the experimentally determined sensitivities of piezoresistive cantilevers. We performed 9200 TSUPREM4 simulations and fabricated 50 devices from six unique process flows; we systematically explored the design space relating process parameters and cantilever sensitivity. Our treatment focuses on piezoresistive cantilevers, but the analytical sensitivity model is extensible to other piezoresistive transducers such as membrane pressure sensors.

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.

Sensitivity Analysis and Optimization of Aerodynamic Configurations with Blend Surfaces

NASA Technical Reports Server (NTRS)

Thomas, A. M.; Tiwari, S. N.

1997-01-01

A novel (geometrical) parametrization procedure using solutions to a suitably chosen fourth order partial differential equation is used to define a class of airplane configurations. Inclusive in this definition are surface grids, volume grids, and grid sensitivity. The general airplane configuration has wing, fuselage, vertical tail and horizontal tail. The design variables are incorporated into the boundary conditions, and the solution is expressed as a Fourier series. The fuselage has circular cross section, and the radius is an algebraic function of four design parameters and an independent computational variable. Volume grids are obtained through an application of the Control Point Form method. A graphic interface software is developed which dynamically changes the surface of the airplane configuration with the change in input design variable. The software is made user friendly and is targeted towards the initial conceptual development of any aerodynamic configurations. Grid sensitivity with respect to surface design parameters and aerodynamic sensitivity coefficients based on potential flow is obtained using an Automatic Differentiation precompiler software tool ADIFOR. Aerodynamic shape optimization of the complete aircraft with twenty four design variables is performed. Unstructured and structured volume grids and Euler solutions are obtained with standard software to demonstrate the feasibility of the new surface definition.

Non-invasive screening for Alzheimer's disease by sensing salivary sugar using Drosophila cells expressing gustatory receptor (Gr5a) immobilized on an extended gate ion-sensitive field-effect transistor (EG-ISFET) biosensor.

PubMed

Lau, Hui-Chong; Lee, In-Kyu; Ko, Pan-Woo; Lee, Ho-Won; Huh, Jeung-Soo; Cho, Won-Ju; Lim, Jeong-Ok

2015-01-01

Body fluids are often used as specimens for medical diagnosis. With the advent of advanced analytical techniques in biotechnology, the diagnostic potential of saliva has been the focus of many studies. We recently reported the presence of excess salivary sugars, in patients with Alzheimer's disease (AD). In the present study, we developed a highly sensitive, cell-based biosensor to detect trehalose levels in patient saliva. The developed biosensor relies on the overexpression of sugar sensitive gustatory receptors (Gr5a) in Drosophila cells to detect the salivary trehalose. The cell-based biosensor was built on the foundation of an improved extended gate ion-sensitive field-effect transistor (EG-ISFET). Using an EG-ISFET, instead of a traditional ion-sensitive field-effect transistor (ISFET), resulted in an increase in the sensitivity and reliability of detection. The biosensor was designed with the gate terminals segregated from the conventional ISFET device. This design allows the construction of an independent reference and sensing region for simultaneous and accurate measurements of samples from controls and patients respectively. To investigate the efficacy of the cell-based biosensor for AD screening, we collected 20 saliva samples from each of the following groups: participants diagnosed with AD, participants diagnosed with Parkinson's disease (PD), and a control group composed of healthy individuals. We then studied the response generated from the interaction of the salivary trehalose of the saliva samples and the Gr5a in the immobilized cells on an EG-ISFET sensor. The cell-based biosensor significantly distinguished salivary sugar, trehalose of the AD group from the PD and control groups. Based on these findings, we propose that salivary trehalose, might be a potential biomarker for AD and could be detected using our cell-based EG-ISFET biosensor. The cell-based EG-ISFET biosensor provides a sensitive and direct approach for salivary sugar detection and may be used in the future as a screening method for AD.

An initial investigation into methods of computing transonic aerodynamic sensitivity coefficients

NASA Technical Reports Server (NTRS)

Carlson, Leland A.

1991-01-01

Continuing studies associated with the development of the quasi-analytical (QA) sensitivity method for three dimensional transonic flow about wings are presented. Furthermore, initial results using the quasi-analytical approach were obtained and compared to those computed using the finite difference (FD) approach. The basic goals achieved were: (1) carrying out various debugging operations pertaining to the quasi-analytical method; (2) addition of section design variables to the sensitivity equation in the form of multiple right hand sides; (3) reconfiguring the analysis/sensitivity package in order to facilitate the execution of analysis/FD/QA test cases; and (4) enhancing the display of output data to allow careful examination of the results and to permit various comparisons of sensitivity derivatives obtained using the FC/QA methods to be conducted easily and quickly. In addition to discussing the above goals, the results of executing subcritical and supercritical test cases are presented.

Local sensitivity of per-recruit fishing mortality reference points.

PubMed

Cadigan, N G; Wang, S

2016-12-01

We study the sensitivity of fishery management per-recruit harvest rates which may be part of a quantitative harvest strategy designed to achieve some objective for catch or population size. We use a local influence sensitivity analysis to derive equations that describe how these reference harvest rates are affected by perturbations to productivity processes. These equations give a basic theoretical understanding of sensitivity that can be used to predict what the likely impacts of future changes in productivity will be. Our results indicate that per-recruit reference harvest rates are more sensitive to perturbations when the equilibrium catch or population size per recruit, as functions of the harvest rate, have less curvature near the reference point. Overall our results suggest that per recruit reference points will, with some exceptions, usually increase if (1) growth rates increase, (2) natural mortality rates increase, or (3) fishery selectivity increases to an older age.

Sensitivity of a fibre scattered-light interferometer to external phase perturbations in an optical fibre

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alekseev, A E; Potapov, V T; Gorshkov, B G

2015-10-31

Sensitivity of a fibre scattered-light interferometer to external phase perturbations is studied for the first time. An expression is derived for an average power of a useful signal at the interferometer output under external harmonic perturbations in a signal fibre of the interferometer. It is shown that the maximum sensitivity of the scattered-light interferometer depends on the dispersion of the interferogram intensity. An average signal-to-noise ratio is determined theoretically and experimentally at the output of the interferometer at different amplitudes of external perturbations. Using the measured dependences of the signal-to-noise ratio, the threshold sensitivity of the fibre scattered-light interferometer tomore » external phase perturbations is found. The results obtained can be used to optimise characteristics of optical time-domain reflectometers and to design individual phase-sensitive fibre-optic sensors. (laser applications and other topics in quantum electronics)« less

Improving Initiation and Tracking of Research Projects at an Academic Health Center: A Case Study.

PubMed

Schmidt, Susanne; Goros, Martin; Parsons, Helen M; Saygin, Can; Wan, Hung-Da; Shireman, Paula K; Gelfond, Jonathan A L

2017-09-01

Research service cores at academic health centers are important in driving translational advancements. Specifically, biostatistics and research design units provide services and training in data analytics, biostatistics, and study design. However, the increasing demand and complexity of assigning appropriate personnel to time-sensitive projects strains existing resources, potentially decreasing productivity and increasing costs. Improving processes for project initiation, assigning appropriate personnel, and tracking time-sensitive projects can eliminate bottlenecks and utilize resources more efficiently. In this case study, we describe our application of lean six sigma principles to our biostatistics unit to establish a systematic continual process improvement cycle for intake, allocation, and tracking of research design and data analysis projects. The define, measure, analyze, improve, and control methodology was used to guide the process improvement. Our goal was to assess and improve the efficiency and effectiveness of operations by objectively measuring outcomes, automating processes, and reducing bottlenecks. As a result, we developed a web-based dashboard application to capture, track, categorize, streamline, and automate project flow. Our workflow system resulted in improved transparency, efficiency, and workload allocation. Using the dashboard application, we reduced the average study intake time from 18 to 6 days, a 66.7% reduction over 12 months (January to December 2015).

Thermal and cryogenic design study for space infrared telescope facility (SIRTF)

NASA Technical Reports Server (NTRS)

Urbach, A. R.; Kelly, T.; Poley, R.

1984-01-01

A study was conducted to determine the ability of an all superfluid helium design to meet the performance requirements of background limited to 200 micrometer, and a two year lifetime for a one meter class free flying infrared observatory. Both a 98 deg and 28.5 deg inclination orbits were examined, and aperture shade designs were developed for both orbits. A unique forebaffle cooling design significantly reduces the sensitivity to aperture heat loads. With certain restrictions on observing modes, the study determined that an all superfluid helium Dewar will meet the temperature and lifetime requirements. A dual cryogen SFHe/SH2 system was also investigated for the 28.5 deg orbit and found to provide a more constant forebaffle temperature but with only a slight improvement in lifetime.

Pain Sensitivity Subgroups in Individuals With Spine Pain: Potential Relevance to Short-Term Clinical Outcome

PubMed Central

Bialosky, Joel E.; Robinson, Michael E.

2014-01-01

Background Cluster analysis can be used to identify individuals similar in profile based on response to multiple pain sensitivity measures. There are limited investigations into how empirically derived pain sensitivity subgroups influence clinical outcomes for individuals with spine pain. Objective The purposes of this study were: (1) to investigate empirically derived subgroups based on pressure and thermal pain sensitivity in individuals with spine pain and (2) to examine subgroup influence on 2-week clinical pain intensity and disability outcomes. Design A secondary analysis of data from 2 randomized trials was conducted. Methods Baseline and 2-week outcome data from 157 participants with low back pain (n=110) and neck pain (n=47) were examined. Participants completed demographic, psychological, and clinical information and were assessed using pain sensitivity protocols, including pressure (suprathreshold pressure pain) and thermal pain sensitivity (thermal heat threshold and tolerance, suprathreshold heat pain, temporal summation). A hierarchical agglomerative cluster analysis was used to create subgroups based on pain sensitivity responses. Differences in data for baseline variables, clinical pain intensity, and disability were examined. Results Three pain sensitivity cluster groups were derived: low pain sensitivity, high thermal static sensitivity, and high pressure and thermal dynamic sensitivity. There were differences in the proportion of individuals meeting a 30% change in pain intensity, where fewer individuals within the high pressure and thermal dynamic sensitivity group (adjusted odds ratio=0.3; 95% confidence interval=0.1, 0.8) achieved successful outcomes. Limitations Only 2-week outcomes are reported. Conclusions Distinct pain sensitivity cluster groups for individuals with spine pain were identified, with the high pressure and thermal dynamic sensitivity group showing worse clinical outcome for pain intensity. Future studies should aim to confirm these findings. PMID:24764070

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harmony, S.C.; Steiner, J.L.; Stumpf, H.J.

The PIUS advanced reactor is a 640-MWe pressurized water reactor developed by Asea Brown Boveri (ABB). A unique feature of the PIUS concept is the absence of mechanical control and shutdown rods. Reactivity is controlled by coolant boron concentration and the temperature of the moderator coolant. As part of the preapplication and eventual design certification process, advanced reactor applicants are required to submit neutronic and thermal-hydraulic safety analyses over a sufficient range of normal operation, transient conditions, and specified accident sequences. Los Alamos is supporting the US Nuclear Regulatory Commission`s preapplication review of the PIUS reactor. A fully one-dimensional modelmore » of the PIUS reactor has been developed for the Transient Reactor Analysis Code, TRACPF1/MOD2. Early in 1992, ABB submitted a Supplemental Information Package describing recent design modifications. An important feature of the PIUS Supplement design was the addition of an active scram system that will function for most transient and accident conditions. A one-dimensional Transient Reactor Analysis Code baseline calculation of the PIUS Supplement design were performed for a break in the main steam line at the outlet nozzle of the loop 3 steam generator. Sensitivity studies were performed to explore the robustness of the PIUS concept to severe off-normal conditions following a main steam line break. The sensitivity study results provide insights into the robustness of the design.« less

Color sensitive silicon photomultiplers with micro-cell level encoding for DOI PET detectors

NASA Astrophysics Data System (ADS)

Shimazoe, Kenji; Koyama, Akihiro; Takahashi, Hiroyuki; Ganka, Thomas; Iskra, Peter; Marquez Seco, Alicia; Schneider, Florian; Wiest, Florian

2017-11-01

There have been many studies on Depth Of Interaction (DOI) identification for high resolution Positron Emission Tomography (PET) systems, including those on phoswich detectors, double-sided readout, light sharing methods, and wavelength discrimination. The wavelength discrimination method utilizes the difference in wavelength of stacked scintillators and requires a color sensitive photodetector. Here, a new silicon photomultiplier (SiPM) coupled to a color filter (colorSiPM) was designed and fabricated for DOI detection. The fabricated colorSiPM has two anode readouts that are sensitive to blue and green color. The colorSiPM's response and DOI identification capability for stacked GAGG and LYSO crystals are characterized. The fabricated colorSiPM is sensitive enough to detect a peak of 662 keV from a 137 Cs source.

The worth of data in predicting aquitard continuity in hydrogeological design

NASA Astrophysics Data System (ADS)

James, Bruce R.; Freeze, R. Allan

1993-07-01

A Bayesian decision framework is developed for addressing questions of hydrogeological data worth associated with engineering design at sites in heterogeneous geological environments. The specific case investigated is one of remedial contaminant containment in an aquifer underlain by an aquitard of uncertain continuity. The framework is used to evaluate the worth of hard and soft data in investigating the aquitard's continuity. The analysis consists of four modules: (1) an aquitard realization generator based on indicator kriging, (2) a procedure for the Bayesian updating of the uncertainty with respect to aquitard windows, (3) a Monte Carlo simulation model for advective contaminant transport, and (4) an economic decision model. A sensitivity analysis for a generic design example involving a design decision between a no-action alternative and a containment alternative indicates that the data worth of a single borehole providing a hard point datum was more sensitive to economic parameters than to hydrogeological or geostatistical parameters. For this case, data worth is very sensitive to the projected cost of containment, the discount rate, and the estimated cost of failure. When it comes to hydrogeological parameters, such as the representative hydraulic conductivity of the aquitard or underlying aquifer, the sensitivity analysis indicates that it is more important to know whether the field value is above or below some threshold value than it is to know its actual numerical value. A good conceptual understanding of the site geology is important in estimating prior uncertainties. The framework was applied in a retrospective fashion to the design of a remediation program for soil contaminated by radioactive waste disposal at the Savannah River site in South Carolina. The cost-effectiveness of different patterns of boreholes was studied. A contour map is presented for the net expected value of sample information (EVSI) for a single borehole. The net EVSI of patterns of precise point measurements is also compared to that of an imprecise seismic survey.

Design Considerations and Performance of MEMS Acoustoelectric Ultrasound Detectors

PubMed Central

Wang, Zhaohui; Ingram, Pier; Greenlee, Charles L.; Olafsson, Ragnar; Norwood, Robert A.; Witte, Russell S.

2014-01-01

Most single-element hydrophones depend on a piezoelectric material that converts pressure changes to electricity. These devices, however, can be expensive, susceptible to damage at high pressure, and/or have limited bandwidth and sensitivity. We have previously described the acoustoelectric (AE) hydrophone as an inexpensive alternative for mapping an ultrasound beam and monitoring acoustic exposure. The device exploits the AE effect, an interaction between electrical current flowing through a material and a propagating pressure wave. Previous designs required imprecise fabrication methods using common laboratory supplies, making it difficult to control basic features such as shape and size. This study describes a different approach based on microelectromechanical systems (MEMS) processing that allows for much finer control of several design features. In an effort to improve the performance of the AE hydrophone, we combine simulations with bench-top testing to evaluate key design features, such as thickness, shape, and conductivity of the active and passive elements. The devices were evaluated in terms of sensitivity, frequency response, and accuracy for reproducing the beam pattern. Our simulations and experimental results both indicated that designs using a combination of indium tin oxide (ITO) for the active element and gold for the passive electrodes (conductivity ratio = ~20) produced the best result for mapping the beam of a 2.25-MHz ultrasound transducer. Also, the AE hydrophone with a rectangular dumbbell configuration achieved a better beam pattern than other shape configurations. Lateral and axial resolutions were consistent with images generated from a commercial capsule hydrophone. Sensitivity of the best-performing device was 1.52 nV/Pa at 500 kPa using a bias voltage of 20 V. We expect a thicker AE hydrophone closer to half the acoustic wavelength to produce even better sensitivity, while maintaining high spectral bandwidth for characterizing medical ultrasound transducers. AE ultrasound detectors may also be useful for monitoring acoustic exposure during therapy or as receivers for photoacoustic imaging. PMID:24658721

Cost and Economics for Advanced Launch Vehicles

NASA Technical Reports Server (NTRS)

Whitfield, Jeff

1998-01-01

Market sensitivity and weight-based cost estimating relationships are key drivers in determining the financial viability of advanced space launch vehicle designs. Due to decreasing space transportation budgets and increasing foreign competition, it has become essential for financial assessments of prospective launch vehicles to be performed during the conceptual design phase. As part of this financial assessment, it is imperative to understand the relationship between market volatility, the uncertainty of weight estimates, and the economic viability of an advanced space launch vehicle program. This paper reports the results of a study that evaluated the economic risk inherent in market variability and the uncertainty of developing weight estimates for an advanced space launch vehicle program. The purpose of this study was to determine the sensitivity of a business case for advanced space flight design with respect to the changing nature of market conditions and the complexity of determining accurate weight estimations during the conceptual design phase. The expected uncertainty associated with these two factors drives the economic risk of the overall program. The study incorporates Monte Carlo simulation techniques to determine the probability of attaining specific levels of economic performance when the market and weight parameters are allowed to vary. This structured approach toward uncertainties allows for the assessment of risks associated with a launch vehicle program's economic performance. This results in the determination of the value of the additional risk placed on the project by these two factors.

Design and operational parameters of a rooftop rainwater harvesting system: definition, sensitivity and verification.

PubMed

Mun, J S; Han, M Y

2012-01-01

The appropriate design and evaluation of a rainwater harvesting (RWH) system is necessary to improve system performance and the stability of the water supply. The main design parameters (DPs) of an RWH system are rainfall, catchment area, collection efficiency, tank volume and water demand. Its operational parameters (OPs) include rainwater use efficiency (RUE), water saving efficiency (WSE) and cycle number (CN). The sensitivity analysis of a rooftop RWH system's DPs to its OPs reveals that the ratio of tank volume to catchment area (V/A) for an RWH system in Seoul, South Korea is recommended between 0.03 and 0.08 in terms of rate of change in RUE. The appropriate design value of V/A is varied with D/A. The extra tank volume up to V/A of 0.15∼0.2 is also available, if necessary to secure more water. Accordingly, we should figure out suitable value or range of DPs based on the sensitivity analysis to optimize design of an RWH system or improve operation efficiency. The operational data employed in this study, which was carried out to validate the design and evaluation method of an RWH system, were obtained from the system in use at a dormitory complex at Seoul National University (SNU) in Korea. The results of these operational data are in good agreement with those used in the initial simulation. The proposed method and the results of this research will be useful in evaluating and comparing the performance of RWH systems. It is found that RUE can be increased by expanding the variety of rainwater uses, particularly in the high rainfall season. Copyright © 2011 Elsevier Ltd. All rights reserved.

Spread spectrum time-resolved diffuse optical measurement system for enhanced sensitivity in detecting human brain activity

NASA Astrophysics Data System (ADS)

Mehta, Kalpesh; Hasnain, Ali; Zhou, Xiaowei; Luo, Jianwen; Penney, Trevor B.; Chen, Nanguang

2017-04-01

Diffuse optical spectroscopy (DOS) and imaging methods have been widely applied to noninvasive detection of brain activity. We have designed and implemented a low cost, portable, real-time one-channel time-resolved DOS system for neuroscience studies. Phantom experiments were carried out to test the performance of the system. We further conducted preliminary human experiments and demonstrated that enhanced sensitivity in detecting neural activity in the cortex could be achieved by the use of late arriving photons.

Sensitivity studies and laboratory measurements for the laser heterodyne spectrometer experiment

NASA Technical Reports Server (NTRS)

Allario, F.; Katzberg, S. J.; Larsen, J. C.

1980-01-01

Several experiments involving spectral scanning interferometers and gas filter correlation radiometers (ref. 2) using limb scanning solar occultation techniques under development for measurements of stratospheric trace gases from Spacelab and satellite platforms are described. An experiment to measure stratospheric trace constituents by Laser Heterodyne Spectroscopy, a summary of sensitivity analyses, and supporting laboratory measurements are presented for O3, ClO, and H2O2 in which the instrument transfer function is modeled using a detailed optical receiver design.

Design, assembly, and metrology of an oil-immersion microscope objective with long working distance

NASA Astrophysics Data System (ADS)

Peng, Wei-Jei; Lin, Wen-Lung; Kuo, Hui-Jean; Ho, Cheng-Fang; Hsu, Wei-Yao

2016-10-01

The design, tolerance sensitivity reduction, assembly, and optical bench test for an oil-immersion microscope objective with long working distance employed in a lattice light-sheet microscope is presented in this paper. In this application, the orthogonal excitation and detection objectives are dipped in an oil medium. The excitation objective focuses the incident laser beam to generate fluorescence on specimen for collecting by detection objective. The excitation objective is custom-designed to meet the requirement specification such as oil-immersion, the long working distance, and numerical aperture (NA) of 0.5, etc. To produce an acceptable point spread function (PSF) for effective excitation, the performance of the objective needs to be close to diffraction limit. Because the tolerance of the modulation transfer function (MTF) is more and more sensitive at higher spatial frequency, it is extremely critical to keep the performance after manufacture. Consequently, an insensitive optical design is very important for relaxing tolerance. We compare the design with and without tolerance sensitivity reduction, and the as-built MTF shows the result. Furthermore, the method for sensitivity reduction is presented. The opto-mechanical design and assembly method are also discussed. Eventually, the objective with five spherical lenses was fabricated. In optical bench test, the depth of the oil is sensitive to MTF, and it leads to the complicated adjustment. For solving this issue, we made an index-matching lens to replace oil for measurement easily. Finally, the measured MTF of the excitation objective can accomplish the requirement specification and successfully employed in a lattice light-sheet microscope.

Use of constrained optimization in the conceptual design of a medium-range subsonic transport

NASA Technical Reports Server (NTRS)

Sliwa, S. M.

1980-01-01

Constrained parameter optimization was used to perform the optimal conceptual design of a medium range transport configuration. The impact of choosing a given performance index was studied, and the required income for a 15 percent return on investment was proposed as a figure of merit. A number of design constants and constraint functions were systematically varied to document the sensitivities of the optimal design to a variety of economic and technological assumptions. A comparison was made for each of the parameter variations between the baseline configuration and the optimally redesigned configuration.

Sensitivity, Specificity, and Public-Health Utility of Clinical Case Definitions Based on the Signs and Symptoms of Cholera in Africa.

PubMed

Nadri, Johara; Sauvageot, Delphine; Njanpop-Lafourcade, Berthe-Marie; Baltazar, Cynthia S; Banla Kere, Abiba; Bwire, Godfrey; Coulibaly, Daouda; Kacou N'Douba, Adele; Kagirita, Atek; Keita, Sakoba; Koivogui, Lamine; Landoh, Dadja E; Langa, Jose P; Miwanda, Berthe N; Mutombo Ndongala, Guy; Mwakapeje, Elibariki R; Mwambeta, Jacob L; Mengel, Martin A; Gessner, Bradford D

2018-04-01

During 2014, Africa reported more than half of the global suspected cholera cases. Based on the data collected from seven countries in the African Cholera Surveillance Network (Africhol), we assessed the sensitivity, specificity, and positive and negative predictive values of clinical cholera case definitions, including that recommended by the World Health Organization (WHO) using culture confirmation as the gold standard. The study was designed to assess results in real-world field situations in settings with recent cholera outbreaks or endemicity. From June 2011 to July 2015, a total of 5,084 persons with suspected cholera were tested for Vibrio cholerae in seven different countries of which 35.7% had culture confirmation. For all countries combined, the WHO case definition had a sensitivity = 92.7%, specificity = 8.1%, positive predictive value = 36.1%, and negative predictive value = 66.6%. Adding dehydration, vomiting, or rice water stools to the case definition could increase the specificity without a substantial decrease in sensitivity. Future studies could further refine our findings primarily by using more sensitive methods for cholera confirmation.

Examining the mediational role of psychological flexibility, pain catastrophizing, and visceral sensitivity in the relationship between psychological distress, irritable bowel symptom frequency, and quality of life.

PubMed

Cassar, G E; Knowles, S; Youssef, G J; Moulding, R; Uiterwijk, D; Waters, L; Austin, D W

2018-06-08

The aim of the current study was to use Structural Equation Modelling (SEM) to examine whether psychological flexibility (i.e. mindfulness, acceptance, valued-living) mediates the relationship between distress, irritable bowel syndrome (IBS) symptom frequency, and quality of life (QoL). Ninety-two individuals participated in the study (12 male, 80 female, M age  = 36.24) by completing an online survey including measures of visceral sensitivity, distress, IBS-related QoL, mindfulness, bowel symptoms, pain catastrophizing, acceptance, and valued-living. A final model with excellent fit was identified. Psychological distress significantly and directly predicted pain catastrophizing, valued-living, and IBS symptom frequency. Pain catastrophizing directly predicted visceral sensitivity and acceptance, while visceral sensitivity significantly and directly predicted IBS symptom frequency and QoL. Symptom frequency also had a direct and significant relationship with QoL. The current findings suggest that interventions designed to address unhelpful cognitive processes related to visceral sensitivity, pain catastrophizing, and psychological distress may be of most benefit to IBS-related QoL.

Design of an adiabatic demagnetization refrigerator for studies in astrophysics

NASA Technical Reports Server (NTRS)

Castles, S.

1983-01-01

An adiabatic demagnetization refrigerator was designed for cooling infrared bolometers for studies in astrophysics and aeronomy. The design was tailored to the requirements of a Shuttle sortie experiment. The refrigerator should be capable of maintaining three bolometers at 0.1 K with a 90% cycle. The advantage are of operations the bolometer at 0.1K. greater sensitivity, faster response time, and the ability to use larger bolometer elements without compromising the response time. The design presented is the first complete design of an ADR intended for use in space. The most important of these specifications are to survive a Shuttle launch, to operate with 1.5 K - 2.0 K space-pumped liquid helium as a heat sink, to have a 90% duty cycle, and to be highly efficient.

Phase I - Final report: Improved position sensitive detectors for thermal neutrons. Design, fabrication, and results of testing the Phase I - Proof-of-Principal Improved Position Sensitive Thermal Neutron Detector Prototype in the laboratory and at the Intense Pulsed Neutron Source (IPNS), Argonne National Laboratory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hull, Carter D.

A position sensitive neutron detector was designed and fabricated with bundles of individual detector elements with diameters of 120 mm. These neutron scintillating fibers were coupled with optoelectronic arrays to produce a ''Fiber Detector.'' A fiber position sensitive detector was completed and tested with scattered and thermal neutrons. Deployment of improved 2D PSDs with high signal to noise ratios at lower costs per area was the overall objective of the project.

Fluorescence-guided tumor visualization using a custom designed NIR attachment to a surgical microscope for high sensitivity imaging (Conference Presentation)

NASA Astrophysics Data System (ADS)

Kittle, David S.; Patil, Chirag G.; Mamelak, Adam; Hansen, Stacey; Perry, Jeff; Ishak, Laura; Black, Keith L.; Butte, Pramod V.

2016-03-01

Current surgical microscopes are limited in sensitivity for NIR fluorescence. Recent developments in tumor markers attached with NIR dyes require newer, more sensitive imaging systems with high resolution to guide surgical resection. We report on a small, single camera solution enabling advanced image processing opportunities previously unavailable for ultra-high sensitivity imaging of these agents. The system captures both visible reflectance and NIR fluorescence at 300 fps while displaying full HD resolution video at 60 fps. The camera head has been designed to easily mount onto the Zeiss Pentero microscope head for seamless integration into surgical procedures.

Correspondence of electroencephalography and near-infrared spectroscopy sensitivities to the cerebral cortex using a high-density layout

PubMed Central

Giacometti, Paolo; Diamond, Solomon G.

2014-01-01

Abstract. This study investigates the correspondence of the cortical sensitivity of electroencephalography (EEG) and near-infrared spectroscopy (NIRS). EEG forward model sensitivity to the cerebral cortex was calculated for 329 EEG electrodes following the 10-5 EEG positioning system using a segmented structural magnetic resonance imaging scan of a human subject. NIRS forward model sensitivity was calculated for the same subject using 156 NIRS source-detector pairs selected from 32 source and 32 detector optodes positioned on the scalp using a subset of the 10-5 EEG positioning system. Sensitivity correlations between colocalized NIRS source-detector pair groups and EEG channels yielded R=0.46±0.08. Groups of NIRS source-detector pairs with maximum correlations to EEG electrode sensitivities are tabulated. The mean correlation between the point spread functions for EEG and NIRS regions of interest (ROI) was R=0.43±0.07. Spherical ROIs with radii of 26 mm yielded the maximum correlation between EEG and NIRS averaged across all cortical mesh nodes. These sensitivity correlations between EEG and NIRS should be taken into account when designing multimodal studies of neurovascular coupling and when using NIRS as a statistical prior for EEG source localization. PMID:25558462

Nanowire size dependence on sensitivity of silicon nanowire field-effect transistor-based pH sensor

NASA Astrophysics Data System (ADS)

Lee, Ryoongbin; Kwon, Dae Woong; Kim, Sihyun; Kim, Sangwan; Mo, Hyun-Sun; Kim, Dae Hwan; Park, Byung-Gook

2017-12-01

In this study, we investigated the effects of nanowire size on the current sensitivity of silicon nanowire (SiNW) ion-sensitive field-effect transistors (ISFETs). The changes in on-current (I on) and resistance according to pH were measured in fabricated SiNW ISFETs of various lengths and widths. As a result, it was revealed that the sensitivity expressed as relative I on change improves as the width decreases. Through technology computer-aided design (TCAD) simulation analysis, the width dependence on the relative I on change can be explained by the observation that the target molecules located at the edge region along the channel width have a stronger effect on the sensitivity as the SiNW width is reduced. Additionally, the length dependence on the sensitivity can be understood in terms of the resistance ratio of the fixed parasitic resistance, including source/drain resistance, to the varying channel resistance as a function of channel length.

Photonic crystal fiber long-period gratings for structural monitoring and chemical sensing

NASA Astrophysics Data System (ADS)

Tang, Jaw-Luen; Wang, Jian-Neng

2008-03-01

We present a simple, low-cost, temperature- and strain-insensitive long-period gratings (LPGs) written in photonic crystal fibers (PCFs) that can be used as sensitive chemical solution sensors or bend sensors for a variety of industrial applications, including civil engineering, aircraft, chemistry, food industry, and biosensing. Three different configurations of PCFs have been used for this study, including a polarization maintaining PCF, a large mode area PCF and an endlessly single mode PCF. These LPGs have been characterized for their sensitivity to temperature, strain, bending, and surrounding refractive index. Transmission spectra of the LPGs were found to exhibit negligible temperature and strain sensitivities, whereas possessing usable sensitivity to refractive index and bending. This type of PCF sensor could in principle be designed for optimum sensitivity to desired measurand(s), while minimizing or removing undesirable cross-sensitivities. The unique sensing features of PCFs are particularly suited for a wide variety of applications in smart structures, embedded materials, telecommunications and sensor systems.

Coexistence of positive and negative refractive index sensitivity in the liquid-core photonic crystal fiber based plasmonic sensor.

PubMed

Shuai, Binbin; Xia, Li; Liu, Deming

2012-11-05

We present and numerically characterize a liquid-core photonic crystal fiber based plasmonic sensor. The coupling properties and sensing performance are investigated by the finite element method. It is found that not only the plasmonic mode dispersion relation but also the fundamental mode dispersion relation is rather sensitive to the analyte refractive index (RI). The positive and negative RI sensitivity coexist in the proposed design. It features a positive RI sensitivity when the increment of the SPP mode effective index is larger than that of the fundamental mode, but the sensor shows a negative RI sensitivity once the increment of the fundamental mode gets larger. A maximum negative RI sensitivity of -5500nm/RIU (Refractive Index Unit) is achieved in the sensing range of 1.50-1.53. The effects of the structural parameters on the plasmonic excitations are also studied, with a view of tuning and optimizing the resonant spectrum.

Demisability and survivability sensitivity to design-for-demise techniques

NASA Astrophysics Data System (ADS)

Trisolini, Mirko; Lewis, Hugh G.; Colombo, Camilla

2018-04-01

The paper is concerned with examining the effects that design-for-demise solutions can have not only on the demisability of components, but also on their survivability that is their capability to withstand impacts from space debris. First two models are introduced. A demisability model to predict the behaviour of spacecraft components during the atmospheric re-entry and a survivability model to assess the vulnerability of spacecraft structures against space debris impacts. Two indices that evaluate the level of demisability and survivability are also proposed. The two models are then used to study the sensitivity of the demisability and of the survivability indices as a function of typical design-for-demise options. The demisability and the survivability can in fact be influenced by the same design parameters in a competing fashion that is while the demisability is improved, the survivability is worsened and vice versa. The analysis shows how the design-for-demise solutions influence the demisability and the survivability independently. In addition, the effect that a solution has simultaneously on the two criteria is assessed. Results shows which, among the design-for-demise parameters mostly influence the demisability and the survivability. For such design parameters maps are presented, describing their influence on the demisability and survivability indices. These maps represent a useful tool to quickly assess the level of demisability and survivability that can be expected from a component, when specific design parameters are changed.

Maternal smoking during pregnancy and offspring conduct problems: Evidence from three independent genetically-sensitive research designs

PubMed Central

Gaysina, Darya; Fergusson, David M.; Leve, Leslie D.; Horwood, John; Reiss, David; Shaw, Daniel S.; Elam, Kit K.; Natsuaki, Misaki N.; Neiderhiser, Jenae M.; Harold, Gordon T.

2013-01-01

Context A number of studies report an association between maternal smoking during pregnancy and offspring conduct disorder. However, past research evidences difficulty disaggregating prenatal environmental from genetic and postnatal environmental influences. Objective To examine the relationship between maternal smoking during pregnancy and offspring conduct problems among children reared by genetically-related and genetically-unrelated mothers. Design, Setting and Participants Three studies employing distinct but complementary research designs were utilized: The Christchurch Health and Development Study (a longitudinal cohort study that includes biological and adopted children), the Early Growth and Development Study (a longitudinal adoption at birth study), and the Cardiff IVF Study (genetically-related and -unrelated families; an adoption at conception study). Maternal smoking during pregnancy was measured as the average number of cigarettes/day (0, 1–9 or 10+) smoked during pregnancy. A number of possible covariates (child gender, ethnicity, birth weight, breast feeding, maternal age at birth, maternal education, family SES, family breakdown, placement age, and parenting practices) were controlled in the analyses. Main Outcome Measure Child conduct problems (age 4–10 years) reported by parents and/or teachers using the Rutter and Conners behaviour scales, the Child Behavior Checklist and Children's Behavior Questionnaire, and the Strengths and Difficulties Questionnaire. Results A significant association between maternal smoking during pregnancy and child conduct problems was observed among children reared by genetically-related and genetically-unrelated mothers. Results from a meta-analysis affirmed this pattern of findings across pooled study samples. Conclusions Findings across the three studies using a complement of genetically-sensitive research designs suggest smoking during pregnancy is a prenatal risk factor for offspring conduct problems, when specific perinatal and postnatal confounding factors are controlled. PMID:23884431

Characterizing Wheel-Soil Interaction Loads Using Meshfree Finite Element Methods: A Sensitivity Analysis for Design Trade Studies

NASA Technical Reports Server (NTRS)

Contreras, Michael T.; Trease, Brian P.; Bojanowski, Cezary; Kulakx, Ronald F.

2013-01-01

A wheel experiencing sinkage and slippage events poses a high risk to planetary rover missions as evidenced by the mobility challenges endured by the Mars Exploration Rover (MER) project. Current wheel design practice utilizes loads derived from a series of events in the life cycle of the rover which do not include (1) failure metrics related to wheel sinkage and slippage and (2) performance trade-offs based on grouser placement/orientation. Wheel designs are rigorously tested experimentally through a variety of drive scenarios and simulated soil environments; however, a robust simulation capability is still in development due to myriad of complex interaction phenomena that contribute to wheel sinkage and slippage conditions such as soil composition, large deformation soil behavior, wheel geometry, nonlinear contact forces, terrain irregularity, etc. For the purposes of modeling wheel sinkage and slippage at an engineering scale, meshfree nite element approaches enable simulations that capture su cient detail of wheel-soil interaction while remaining computationally feasible. This study implements the JPL wheel-soil benchmark problem in the commercial code environment utilizing the large deformation modeling capability of Smooth Particle Hydrodynamics (SPH) meshfree methods. The nominal, benchmark wheel-soil interaction model that produces numerically stable and physically realistic results is presented and simulations are shown for both wheel traverse and wheel sinkage cases. A sensitivity analysis developing the capability and framework for future ight applications is conducted to illustrate the importance of perturbations to critical material properties and parameters. Implementation of the proposed soil-wheel interaction simulation capability and associated sensitivity framework has the potential to reduce experimentation cost and improve the early stage wheel design proce

Map Sensitivity vs. Map Dependency: A Case Study of Subway Maps’ Impact on Passenger Route Choices in Washington DC

PubMed Central

Xu, John

2017-01-01

This paper addresses the key assumption in behavioral and transportation planning literature that, when people use a transit system more frequently, they become less dependent on and less sensitive to transit maps in their decision-making. Therefore, according to this assumption, map changes are much less impactful to travel decisions of frequent riders than to that of first-time or new passengers. This assumption—though never empirically validated—has been the major hurdle for transit maps to becoming a planning tool to change passengers’ behavior. This paper examines this assumption using the Washington DC metro map as a case study by conducting a route choice experiment between 30 Origin-Destination (O-D) pairs on seven metro map designs. The experiment targets two types of passengers: frequent metro riders through advertisements on a free daily newspaper available at DC metro stations, and general residents in the Washington metropolitan area through Amazon Mechanical Turk, an online crowdsourcing platform. A total of 255 and 371 participants made 2024 and 2960 route choices in the respective experiments. The results show that frequent passengers are in fact more sensitive to subtle changes in map design than general residents who are less likely to be familiar with the metro map and therefore unaffected by map changes presented in the alternative designs. The work disproves the aforementioned assumption and further validates metro maps as an effective planning tool in transit systems. PMID:29068371

High-field modulated ion-selective field-effect-transistor (FET) sensors with sensitivity higher than the ideal Nernst sensitivity.

PubMed

Chen, Yi-Ting; Sarangadharan, Indu; Sukesan, Revathi; Hseih, Ching-Yen; Lee, Geng-Yen; Chyi, Jen-Inn; Wang, Yu-Lin

2018-05-29

Lead ion selective membrane (Pb-ISM) coated AlGaN/GaN high electron mobility transistors (HEMT) was used to demonstrate a whole new methodology for ion-selective FET sensors, which can create ultra-high sensitivity (-36 mV/log [Pb 2+ ]) surpassing the limit of ideal sensitivity (-29.58 mV/log [Pb 2+ ]) in a typical Nernst equation for lead ion. The largely improved sensitivity has tremendously reduced the detection limit (10 -10  M) for several orders of magnitude of lead ion concentration compared to typical ion-selective electrode (ISE) (10 -7  M). The high sensitivity was obtained by creating a strong filed between the gate electrode and the HEMT channel. Systematical investigation was done by measuring different design of the sensor and gate bias, indicating ultra-high sensitivity and ultra-low detection limit obtained only in sufficiently strong field. Theoretical study in the sensitivity consistently agrees with the experimental finding and predicts the maximum and minimum sensitivity. The detection limit of our sensor is comparable to that of Inductively-Coupled-Plasma Mass Spectrum (ICP-MS), which also has detection limit near 10 -10  M.

Performance evaluation of a lossy transmission lines based diode detector at cryogenic temperature.

PubMed

Villa, E; Aja, B; de la Fuente, L; Artal, E

2016-01-01

This work is focused on the design, fabrication, and performance analysis of a square-law Schottky diode detector based on lossy transmission lines working under cryogenic temperature (15 K). The design analysis of a microwave detector, based on a planar gallium-arsenide low effective Schottky barrier height diode, is reported, which is aimed for achieving large input return loss as well as flat sensitivity versus frequency. The designed circuit demonstrates good sensitivity, as well as a good return loss in a wide bandwidth at Ka-band, at both room (300 K) and cryogenic (15 K) temperatures. A good sensitivity of 1000 mV/mW and input return loss better than 12 dB have been achieved when it works as a zero-bias Schottky diode detector at room temperature, increasing the sensitivity up to a minimum of 2200 mV/mW, with the need of a DC bias current, at cryogenic temperature.

Targeting HSP70-induced thermotolerance for design of thermal sensitizers.

PubMed

Calderwood, S K; Asea, A

2002-01-01

Thermal therapy has been shown to be an extremely powerful anti-cancer agent and a potent radiation sensitizer. However, the full potential of thermal therapy is hindered by a number of considerations including highly conserved heat resistance pathways in tumour cells and inhomogeneous heating of deep-seated tumours due to energy deposition and perfusion issues. This report reviews recent progress in the development of hyperthermia sensitizing drugs designed to specifically amplify the effects of hyperthermia. Such agents might be particularly useful in situations where heating is not adequate for the full biological effect or is not homogeneously delivered to tumours. The particular pathway concentrated on is thermotolerance, a complex, inducible cellular response that leads to heat resistance. This paper will concentrate on the molecular pathways of thermotolerance induction for designing inhibitors of heat resistance/thermal sensitizers, which may allow the full potential of thermal therapy to be utilized.

Design and Performance of the Antenna-Coupled Lumped-Element Kinetic Inductance Detector

NASA Astrophysics Data System (ADS)

Barry, P. S.; Doyle, S.; Hornsby, A. L.; Kofman, A.; Mayer, E.; Nadolski, A.; Tang, Q. Y.; Vieira, J.; Shirokoff, E.

2018-05-01

Focal plane arrays consisting of low-noise, polarisation-sensitive detectors have made possible the pioneering advances in the study of the cosmic microwave background (CMB). To make further progress, the next generation of CMB experiments (e.g. CMB-S4) will require a substantial increase in the number of detectors compared to current instruments. Arrays of kinetic inductance detectors (KIDs) provide a possible path to realising such large-format arrays owing to their intrinsic multiplexing advantage and relative cryogenic simplicity. In this paper, we report on the design of a variant of the traditional KID design: the antenna-coupled lumped-element KID. A polarisation-sensitive twin-slot antenna placed behind an optimised hemispherical lens couples power onto a thin-film superconducting microstrip line. The power is then guided into the inductive section of an aluminium KID, where it is absorbed and modifies both the resonant frequency and quality factor of the KID. We present the various aspects of the design and preliminary results from the first set of seven-element prototype arrays and compare to the expected modelled performance.

Investigation of Advanced Radar Techniques for Atmospheric Hazard Detection with Airborne Weather Radar

NASA Technical Reports Server (NTRS)

Pazmany, Andrew L.

2014-01-01

In 2013 ProSensing Inc. conducted a study to investigate the hazard detection potential of aircraft weather radars with new measurement capabilities, such as multi-frequency, polarimetric and radiometric modes. Various radar designs and features were evaluated for sensitivity, measurement range and for detecting and quantifying atmospheric hazards in wide range of weather conditions. Projected size, weight, power consumption and cost of the various designs were also considered. Various cloud and precipitation conditions were modeled and used to conduct an analytic evaluation of the design options. This report provides an overview of the study and summarizes the conclusions and recommendations.

Optimization of the Manufacturing Process of Conical Shell Structures Using Prepreg Laminatees

NASA Astrophysics Data System (ADS)

Khakimova, Regina; Zimmermann, Rolf; Burau, Florian; Siebert, Marc; Arbelo, Mariano; Castro, Saullo; Degenhardt, Richard

2014-06-01

The design and manufacture of an unstiffened composite conical structure which is a scaled-down version of the Ariane 5 Midlife Evolution Equipment Bay Structure is presented. For such benchmarking structures the fiber orientation error is critical and then the manufacturing process becomes a big challenge. The paper therefore is focused on the implementation of a tailoring study and on the manufacturing process. The conical structure will be tested to validate a new design approach.This study contributes to the European Union (EU) project DESICOS, whose aim is to develop less conservative design guidelines for imperfection sensitive thin-walled structures.

Aerodynamics as a subway design parameter

NASA Technical Reports Server (NTRS)

Kurtz, D. W.

1976-01-01

A parametric sensitivity study has been performed on the system operational energy requirement in order to guide subway design strategy. Aerodynamics can play a dominant or trivial role, depending upon the system characteristics. Optimization of the aerodynamic parameters may not minimize the total operational energy. Isolation of the station box from the tunnel and reduction of the inertial power requirements pay the largest dividends in terms of the operational energy requirement.

A novel regenerative shock absorber with a speed doubling mechanism and its Monte Carlo simulation

NASA Astrophysics Data System (ADS)

Zhang, Ran; Wang, Xu; Liu, Zhenwei

2018-03-01

A novel regenerative shock absorber has been designed and fabricated. The novelty of the presented work is the application of the double speed regenerative shock absorber that utilizes the rack and pinion mechanism to increase the magnet speed with respect to the coils for higher power output. The simulation models with parameters identified from finite element analysis and the experiments are developed. The proposed regenerative shock absorber is compared with the regenerative shock absorber without the rack and pinion mechanism, when they are integrated into the same quarter vehicle suspension system. The sinusoidal wave road profile displacement excitation and the random road profile displacement excitation with peak amplitude of 0.035 m are applied as the inputs in the frequency range of 0-25 Hz. It is found that with the sinusoidal and random road profile displacement input, the proposed innovative design can increase the output power by 4 times comparing to the baseline design. The proposed double speed regenerative shock absorber also presents to be more sensitive to the road profile irregularity than the single speed regenerative shock absorber as suggested by Monte Carlo simulation. Lastly the coil mass and amplification factor are studied for sensitivity analysis and performance optimization, which provides a general design method of the regenerative shock absorbers. It shows that for the system power output, the proposed design becomes more sensitive to either the coil mass or amplification factor depending on the amount of the coil mass. With the specifically selected combination of the coil mass and amplification factor, the optimized energy harvesting performance can be achieved.

Social reward and social punishment sensitivity in relation to dietary restraint and binge/purge symptoms.

PubMed

Fussner, Lauren M; Luebbe, Aaron M; Smith, April R

2018-08-01

Disordered eating symptoms are associated with disrupted sensitivity to reward and punishment, broadly assessed. However, it is unknown how eating pathology is related to sensitivity to social reward and social punishment specifically. Drawing on Reinforcement Sensitivity Theory, the current study utilized a multi-method design to test whether disordered eating symptoms, specifically dietary restraint (DR) and binge/purge (BP), were similarly or uniquely related to sensitivity to social punishment and social reward. Female university students (N = 110, M = 18.66, SD = 0.89) completed self-report measures and a novel behavioral task measuring willingness to work for or to avoid social feedback. DR and BP symptoms were related to increased self-reported and behavioral sensitivity to social punishment, yet only when symptoms were tested in isolation. DR was associated with increased sensitivity to social reward across self-report and behavioral paradigms. BP symptoms were uniquely and positively related to self-reported sensitivity to social reward, but decreased behavioral sensitivity to social reward. Findings suggest that sensitivity to punishment may be a common factor related to DR and BP, whereas sensitivity to social reward may be a key factor differentiating disordered eating symptoms. Copyright © 2018 Elsevier Ltd. All rights reserved.

Study design for a randomized controlled trial to increase the relative reinforcing value of vegetable consumption using incentive sensitization among obese and overweight people

USDA-ARS?s Scientific Manuscript database

Federal dietary guidance recommends consumption of a variety of vegetables, but Americans only consume a small fraction of recommended amounts. Studies have attempted to increase consumption with modest results. In this manuscript, we present the protocol for a study that applies incentive sensitiza...

Sensitization to Alternaria and Cladosporium in patients with respiratory allergy and outdoor counts of mold spores in Ankara atmosphere, Turkey.

PubMed

Bavbek, Sevim; Erkekol, Ferda Oner; Ceter, Talip; Mungan, Dilşad; Ozer, Faruk; Pinar, Münevver; Misirligil, Zeynep

2006-08-01

Sensitization to Alternaria and Cladosporium has been reported to be 3% to 30% in European countries. However, in Turkey, there is limited data about the prevalence of sensitization to these molds and the intensity of the two mold spores in Ankara atmosphere. This study was designed to evaluate the sensitization to Alternaria and Cladosporium in patients with respiratory allergy in Ankara and also the concentration of the two molds in Ankara atmosphere. Allergic rhinitis and asthma patients living in Ankara were included in the study. Demographic and diagnostic data of the patients were recorded. A skin prick test with extracts supplied by three different laboratories was used to evaluate the sensitization to Alternaria and Cladosporium. Mold spores were measured using a Burkard 7-day recording volumetric spore trap in Ankara atmosphere during a year. Overall sensitization to the two molds was found to be 14.8%, and isolated Alternaria or Cladosporiumsensitization was 3%. Considering the positive reaction to at least one of the three suppliers, the sensitization rate was 11.9% and 8.1% for Alternaria and Cladosporium, respectively. Cochran's Q homogenization test demonstrated that the positive and negative reaction were not homogeneous among three laboratories. The total number of mold spores in Ankara atmosphere was 429,264 spores/m3 of which 75.5% and 6% were constituted by Cladosporium and Alternaria, respectively. The prevalence of Cladosporium and Alternaria sensitization in respiratory allergy patients is quite similar to European countries; however, our data indicate that commercial mold extracts should be standardized to establish the real sensitization rates. Additionally, considering the great numbers of these mold spores in Ankara atmosphere, long-term follow-up studies are needed to evaluate the relationship between the mold load and sensitization patterns.

Direct Comparison of Two New Actigraphs and Polysomnography in Children and Adolescents

PubMed Central

Meltzer, Lisa J.; Walsh, Colleen M.; Traylor, Joel; Westin, Anna M. L.

2012-01-01

Study Objectives: To evaluate the validity and reliability of 2 new models of commercially available actigraphs compared to polysomnography for children and adolescents. Design and Setting: Subjects concurrently wore the Ambulatory Monitoring Inc. Motionlogger Sleep Watch (AMI) and the Phillips Respironics Mini-Mitter Actiwatch-2 (PRMM) while undergoing overnight polysomnography (PSG) in a pediatric sleep laboratory housed in a tertiary care children's hospital. Participants: 115 youth (59 girls, 56 boys), ages 3-18 years (mean 8.8 years, SD 4.4 years). Measurements: Outcome variables were total sleep time (TST), wake after sleep onset (WASO), and sleep efficiency (SE). Epoch-by-epoch comparisons were made between the 2 devices and PSG to determine sensitivity, specificity, and accuracy. Agreement between the 2 devices was determined with t-tests and the Bland-Altman concordance technique. Different algorithms/sensitivities, developmental age groups, and sleep disordered breathing (SDB) status were also examined. Results: For both device brands, sensitivity (0.89-0.97), specificity (0.54-0.77), and accuracy (0.87-0.90) were similar to previous reports. Notably, compared to PSG, both device brands significantly overestimated WASO, while the AMI device also significantly underestimated TST. Inter-device comparison of the 2 brands found poor agreement for TST, WASO, and SE. Agreement with PSG differed depending on the scoring algorithm (AMI) or sensitivity setting (PRMM), as well as across developmental age group and sleep disordered breathing (SDB) status. Conclusions: Similar to previous reports, both new actigraph brands were found to have good sensitivity (to detect sleep), but poorer specificity (to detect wake). Study results also suggest that researchers should adjust the scoring algorithm/sensitivity depending on a study's design (e.g., young children vs. adolescents, healthy children vs. youth with SDB). Further, inter-device reliability was poor, suggesting the need for caution when comparing results across studies that use different brands of actigraphic devices. Citation: Meltzer LJ; Walsh CM; Traylor J; Westin AML. Direct comparison of two new actigraphs and polysomnography in children and adolescents. SLEEP 2012;35(1):159-166. PMID:22215930

Systematic parameter estimation and sensitivity analysis using a multidimensional PEMFC model coupled with DAKOTA.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Chao Yang; Luo, Gang; Jiang, Fangming

2010-05-01

Current computational models for proton exchange membrane fuel cells (PEMFCs) include a large number of parameters such as boundary conditions, material properties, and numerous parameters used in sub-models for membrane transport, two-phase flow and electrochemistry. In order to successfully use a computational PEMFC model in design and optimization, it is important to identify critical parameters under a wide variety of operating conditions, such as relative humidity, current load, temperature, etc. Moreover, when experimental data is available in the form of polarization curves or local distribution of current and reactant/product species (e.g., O2, H2O concentrations), critical parameters can be estimated inmore » order to enable the model to better fit the data. Sensitivity analysis and parameter estimation are typically performed using manual adjustment of parameters, which is also common in parameter studies. We present work to demonstrate a systematic approach based on using a widely available toolkit developed at Sandia called DAKOTA that supports many kinds of design studies, such as sensitivity analysis as well as optimization and uncertainty quantification. In the present work, we couple a multidimensional PEMFC model (which is being developed, tested and later validated in a joint effort by a team from Penn State Univ. and Sandia National Laboratories) with DAKOTA through the mapping of model parameters to system responses. Using this interface, we demonstrate the efficiency of performing simple parameter studies as well as identifying critical parameters using sensitivity analysis. Finally, we show examples of optimization and parameter estimation using the automated capability in DAKOTA.« less

Sensitivity Enhancement in Si Nanophotonic Waveguides Used for Refractive Index Sensing

PubMed Central

Shi, Yaocheng; Ma, Ke; Dai, Daoxin

2016-01-01

A comparative study is given for the sensitivity of several typical Si nanophotonic waveguides, including SOI (silicon-on-insulator) nanowires, nanoslot waveguides, suspended Si nanowires, and nanofibers. The cases for gas sensing (ncl ~ 1.0) and liquid sensing (ncl ~ 1.33) are considered. When using SOI nanowires (with a SiO2 buffer layer), the sensitivity for liquid sensing (S ~ 0.55) is higher than that for gas sensing (S ~ 0.35) due to lower asymmetry in the vertical direction. By using SOI nanoslot waveguides, suspended Si nanowires, and Si nanofibers, one could achieve a higher sensitivity compared to sensing with a free-space beam (S = 1.0). The sensitivity for gas sensing is higher than that for liquid sensing due to the higher index-contrast. The waveguide sensitivity of an optimized suspended Si nanowire for gas sensing is as high as 1.5, which is much higher than that of a SOI nanoslot waveguide. Furthermore, the optimal design has very large tolerance to the core width variation due to the fabrication error (∆w ~ ±50 nm). In contrast, a Si nanofiber could also give a very high sensitivity (e.g., ~1.43) while the fabrication tolerance is very small (i.e., ∆w < ±5 nm). The comparative study shows that suspended Si nanowire is a good choice to achieve ultra-high waveguide sensitivity. PMID:26950132

Sensitivity Enhancement in Si Nanophotonic Waveguides Used for Refractive Index Sensing.

PubMed

Shi, Yaocheng; Ma, Ke; Dai, Daoxin

2016-03-03

A comparative study is given for the sensitivity of several typical Si nanophotonic waveguides, including SOI (silicon-on-insulator) nanowires, nanoslot waveguides, suspended Si nanowires, and nanofibers. The cases for gas sensing (ncl ~ 1.0) and liquid sensing (ncl ~ 1.33) are considered. When using SOI nanowires (with a SiO₂ buffer layer), the sensitivity for liquid sensing (S ~ 0.55) is higher than that for gas sensing (S ~ 0.35) due to lower asymmetry in the vertical direction. By using SOI nanoslot waveguides, suspended Si nanowires, and Si nanofibers, one could achieve a higher sensitivity compared to sensing with a free-space beam (S = 1.0). The sensitivity for gas sensing is higher than that for liquid sensing due to the higher index-contrast. The waveguide sensitivity of an optimized suspended Si nanowire for gas sensing is as high as 1.5, which is much higher than that of a SOI nanoslot waveguide. Furthermore, the optimal design has very large tolerance to the core width variation due to the fabrication error (∆w ~ ±50 nm). In contrast, a Si nanofiber could also give a very high sensitivity (e.g., ~1.43) while the fabrication tolerance is very small (i.e., ∆w < ±5 nm). The comparative study shows that suspended Si nanowire is a good choice to achieve ultra-high waveguide sensitivity.

Nuclear Data Needs for Generation IV Nuclear Energy Systems

NASA Astrophysics Data System (ADS)

Rullhusen, Peter

2006-04-01

Nuclear data needs for generation IV systems. Future of nuclear energy and the role of nuclear data / P. Finck. Nuclear data needs for generation IV nuclear energy systems-summary of U.S. workshop / T. A. Taiwo, H. S. Khalil. Nuclear data needs for the assessment of gen. IV systems / G. Rimpault. Nuclear data needs for generation IV-lessons from benchmarks / S. C. van der Marck, A. Hogenbirk, M. C. Duijvestijn. Core design issues of the supercritical water fast reactor / M. Mori ... [et al.]. GFR core neutronics studies at CEA / J. C. Bosq ... [et al]. Comparative study on different phonon frequency spectra of graphite in GCR / Young-Sik Cho ... [et al.]. Innovative fuel types for minor actinides transmutation / D. Haas, A. Fernandez, J. Somers. The importance of nuclear data in modeling and designing generation IV fast reactors / K. D. Weaver. The GIF and Mexico-"everything is possible" / C. Arrenondo Sánchez -- Benmarks, sensitivity calculations, uncertainties. Sensitivity of advanced reactor and fuel cycle performance parameters to nuclear data uncertainties / G. Aliberti ... [et al.]. Sensitivity and uncertainty study for thermal molten salt reactors / A. Biduad ... [et al.]. Integral reactor physics benchmarks- The International Criticality Safety Benchmark Evaluation Project (ICSBEP) and the International Reactor Physics Experiment Evaluation Project (IRPHEP) / J. B. Briggs, D. W. Nigg, E. Sartori. Computer model of an error propagation through micro-campaign of fast neutron gas cooled nuclear reactor / E. Ivanov. Combining differential and integral experiments on [symbol] for reducing uncertainties in nuclear data applications / T. Kawano ... [et al.]. Sensitivity of activation cross sections of the Hafnium, Tanatalum and Tungsten stable isotopes to nuclear reaction mechanisms / V. Avrigeanu ... [et al.]. Generating covariance data with nuclear models / A. J. Koning. Sensitivity of Candu-SCWR reactors physics calculations to nuclear data files / K. S. Kozier, G. R. Dyck. The lead cooled fast reactor benchmark BREST-300: analysis with sensitivity method / V. Smirnov ... [et al.]. Sensitivity analysis of neutron cross-sections considered for design and safety studies of LFR and SFR generation IV systems / K. Tucek, J. Carlsson, H. Wider -- Experiments. INL capabilities for nuclear data measurements using the Argonne intense pulsed neutron source facility / J. D. Cole ... [et al.]. Cross-section measurements in the fast neutron energy range / A. Plompen. Recent measurements of neutron capture cross sections for minor actinides by a JNC and Kyoto University Group / H. Harada ... [et al.]. Determination of minor actinides fission cross sections by means of transfer reactions / M. Aiche ... [et al.] -- Evaluated data libraries. Nuclear data services from the NEA / H. Henriksson, Y. Rugama. Nuclear databases for energy applications: an IAEA perspective / R. Capote Noy, A. L. Nichols, A. Trkov. Nuclear data evaluation for generation IV / G. Noguère ... [et al.]. Improved evaluations of neutron-induced reactions on americium isotopes / P. Talou ... [et al.]. Using improved ENDF-based nuclear data for candu reactor calculations / J. Prodea. A comparative study on the graphite-moderated reactors using different evaluated nuclear data / Do Heon Kim ... [et al.].

Designing a chevron unit for a microelectronic position-sensitive detector with two microchannel plates

NASA Astrophysics Data System (ADS)

Kosulya, A. V.; Verbitskii, V. G.

2017-09-01

The dependence of the transverse section of an electron beam on the distance between plates and on the accelerating potential difference is determined for a chevron unit of a microelectronic position-sensitive detector (MPSD) with two microchannel plates. The geometry of the MPSD chevron unit is designed and optimized.

Near infrared photography with a vacuum-cold camera. [Orion nebula observation

NASA Technical Reports Server (NTRS)

Rossano, G. S.; Russell, R. W.; Cornett, R. H.

1980-01-01

Sensitized cooled plates have been obtained of the Orion nebula region and of Sh2-149 in the wavelength ranges 8000 A-9000 A and 9,000 A-11,000 A with a recently designed and constructed vacuum-cold camera. Sensitization procedures are described and the camera design is presented.

Predicting chemically-induced skin reactions. Part II: QSAR models of skin permeability and the relationships between skin permeability and skin sensitization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alves, Vinicius M.; Laboratory for Molecular Modeling, Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599; Muratov, Eugene

Skin permeability is widely considered to be mechanistically implicated in chemically-induced skin sensitization. Although many chemicals have been identified as skin sensitizers, there have been very few reports analyzing the relationships between molecular structure and skin permeability of sensitizers and non-sensitizers. The goals of this study were to: (i) compile, curate, and integrate the largest publicly available dataset of chemicals studied for their skin permeability; (ii) develop and rigorously validate QSAR models to predict skin permeability; and (iii) explore the complex relationships between skin sensitization and skin permeability. Based on the largest publicly available dataset compiled in this study, wemore » found no overall correlation between skin permeability and skin sensitization. In addition, cross-species correlation coefficient between human and rodent permeability data was found to be as low as R{sup 2} = 0.44. Human skin permeability models based on the random forest method have been developed and validated using OECD-compliant QSAR modeling workflow. Their external accuracy was high (Q{sup 2}{sub ext} = 0.73 for 63% of external compounds inside the applicability domain). The extended analysis using both experimentally-measured and QSAR-imputed data still confirmed the absence of any overall concordance between skin permeability and skin sensitization. This observation suggests that chemical modifications that affect skin permeability should not be presumed a priori to modulate the sensitization potential of chemicals. The models reported herein as well as those developed in the companion paper on skin sensitization suggest that it may be possible to rationally design compounds with the desired high skin permeability but low sensitization potential. - Highlights: • It was compiled the largest publicly-available skin permeability dataset. • Predictive QSAR models were developed for skin permeability. • No concordance between skin sensitization and skin permeability has been found. • Structural rules for optimizing sensitization and penetration were established.« less

Estimating and Enhancing Public Transit Accessibility for People with Mobility Limitations

DOT National Transportation Integrated Search

2017-06-30

This two-part study employs fine-scale performance measures and analytical techniques designed to evaluate and improve transit services for people experiencing disability. Part one puts forth a series of time-sensitive, general transit feed system (G...

Similitude design for the vibration problems of plates and shells: A review

NASA Astrophysics Data System (ADS)

Zhu, Yunpeng; Wang, You; Luo, Zhong; Han, Qingkai; Wang, Deyou

2017-06-01

Similitude design plays a vital role in the analysis of vibration and shock problems encountered in large engineering equipment. Similitude design, including dimensional analysis and governing equation method, is founded on the dynamic similitude theory. This study reviews the application of similitude design methods in engineering practice and summarizes the major achievements of the dynamic similitude theory in structural vibration and shock problems in different fields, including marine structures, civil engineering structures, and large power equipment. This study also reviews the dynamic similitude design methods for thin-walled and composite material plates and shells, including the most recent work published by the authors. Structure sensitivity analysis is used to evaluate the scaling factors to attain accurate distorted scaling laws. Finally, this study discusses the existing problems and the potential of the dynamic similitude theory for the analysis of vibration and shock problems of structures.

Conceptual design of a lunar oxygen pilot plant Lunar Base Systems Study (LBSS) task 4.2

NASA Technical Reports Server (NTRS)

1988-01-01

The primary objective was to develop conceptual designs of two pilot plants to produce oxygen from lunar materials. A lunar pilot plant will be used to generate engineering data necessary to support an optimum design of a larger scale production plant. Lunar oxygen would be of primary value as spacecraft propellant oxidizer. In addition, lunar oxygen would be useful for servicing nonregenerative fuel cell power systems, providing requirements for life support, and to make up oxygen losses from leakage and airlock cycling. Thirteen different lunar oxygen production methods are described. Hydrogen reduction of ilmenite and extraction of solar-wind hydrogen from bulk lunar soil were selected for conceptual design studies. Trades and sensitivity analyses were performed with these models.

Integrating Flight Dynamics & Control Analysis and Simulation in Rotorcraft Conceptual Design

NASA Technical Reports Server (NTRS)

Lawrence, Ben; Berger, Tom; Tischler, Mark B.; Theodore, Colin R; Elmore, Josh; Gallaher, Andrew; Tobias, Eric L.

2016-01-01

The development of a toolset, SIMPLI-FLYD ('SIMPLIfied FLight dynamics for conceptual Design') is described. SIMPLI-FLYD is a collection of tools that perform flight dynamics and control modeling and analysis of rotorcraft conceptual designs including a capability to evaluate the designs in an X-Plane-based real-time simulation. The establishment of this framework is now facilitating the exploration of this new capability, in terms of modeling fidelity and data requirements, and the investigation of which stability and control and handling qualities requirements are appropriate for conceptual design. Illustrative design variation studies for single main rotor and tiltrotor vehicle configurations show sensitivity of the stability and control characteristics and an approach to highlight potential weight savings by identifying over-design.

Studies on Flat Sandwich-type Self-Powered Detectors for Flux Measurements in ITER Test Blanket Modules

NASA Astrophysics Data System (ADS)

Raj, Prasoon; Angelone, Maurizio; Döring, Toralf; Eberhardt, Klaus; Fischer, Ulrich; Klix, Axel; Schwengner, Ronald

2018-01-01

Neutron and gamma flux measurements in designated positions in the test blanket modules (TBM) of ITER will be important tasks during ITER's campaigns. As part of the ongoing task on development of nuclear instrumentation for application in European ITER TBMs, experimental investigations on self-powered detectors (SPD) are undertaken. This paper reports the findings of neutron and photon irradiation tests performed with a test SPD in flat sandwich-like geometry. Whereas both neutrons and gammas can be detected with appropriate optimization of geometries, materials and sizes of the components, the present sandwich-like design is more sensitive to gammas than 14 MeV neutrons. Range of SPD current signals achievable under TBM conditions are predicted based on the SPD sensitivities measured in this work.

Simulation study of electric-guided delivery of 0.4µm monodisperse and polydisperse aerosols to the ostiomeatal complex.

PubMed

Xi, Jinxiang; Yuan, Jiayao Eddie; Si, Xiuhua April

2016-05-01

Despite the high prevalence of rhinosinusitis, current inhalation therapy shows limited efficacy due to extremely low drug delivery efficiency to the paranasal sinuses. Novel intranasal delivery systems are needed to enhance targeted delivery to the sinus with therapeutic dosages. An optimization framework for intranasal drug delivery was developed to target polydisperse charged aerosols to the ostiomeatal complex (OMC) with electric guidance. The delivery efficiency of a group of charged aerosols recently reported in the literature was numerically assessed and optimized in an anatomically accurate nose-sinus model. Key design variables included particle charge number, particle size and distribution, electrode strength, and inhalation velocity. Both monodisperse and polydisperse aerosol profiles were considered. Results showed that the OMC delivery efficiency was highly sensitive to the applied electric field and electrostatic charges carried by the particles. Through the synthesis of electric-guidance and point drug release, focused deposition with significantly enhanced dosage in the OMC can be achieved. For 0.4 µm charged aerosols, an OMC delivery efficiency of 51.6% was predicted for monodisperse aerosols and 34.4% for polydisperse aerosols. This difference suggested that the aerosol profile exerted a notable effect on intranasal deliveries. Sensitivity analysis indicated that the OMC deposition fraction was highly sensitive to the charge and size of particles and was less sensitive to the inhalation velocity considered in this study. Experimental studies are needed to validate the numerically optimized designs. Further studies are warranted to investigate the targeted OMC delivery with both electric and acoustics controls, the latter of which has the potential to further deliver the drug particles into the sinus cavity. Copyright © 2016 Elsevier Ltd. All rights reserved.

Interfacial chemistry and the design of solid-phase nucleic acid hybridization assays using immobilized quantum dots as donors in fluorescence resonance energy transfer.

PubMed

Algar, W Russ; Krull, Ulrich J

2011-01-01

The use of quantum dots (QDs) as donors in fluorescence resonance energy transfer (FRET) offer several advantages for the development of multiplexed solid-phase QD-FRET nucleic acid hybridization assays. Designs for multiplexing have been demonstrated, but important challenges remain in the optimization of these systems. In this work, we identify several strategies based on the design of interfacial chemistry for improving sensitivity, obtaining lower limits of detection (LOD) and enabling the regeneration and reuse of solid-phase QD-FRET hybridization assays. FRET-sensitized emission from acceptor dyes associated with hybridization events at immobilized QD donors provides the analytical signal in these assays. The minimization of active sensing area reduces background from QD donor PL and allows the resolution of smaller amounts of acceptor emission, thus lowering the LOD. The association of multiple acceptor dyes with each hybridization event can enhance FRET efficiency, thereby improving sensitivity. Many previous studies have used interfacial protein layers to generate selectivity; however, transient destabilization of these layers is shown to prevent efficient regeneration. To this end, we report a protein-free interfacial chemistry and demonstrate the specific detection of as little as 2 pmol of target, as well as an improved capacity for regeneration.

Interfacial Chemistry and the Design of Solid-Phase Nucleic Acid Hybridization Assays Using Immobilized Quantum Dots as Donors in Fluorescence Resonance Energy Transfer

PubMed Central

Algar, W. Russ; Krull, Ulrich J.

2011-01-01

The use of quantum dots (QDs) as donors in fluorescence resonance energy transfer (FRET) offer several advantages for the development of multiplexed solid-phase QD-FRET nucleic acid hybridization assays. Designs for multiplexing have been demonstrated, but important challenges remain in the optimization of these systems. In this work, we identify several strategies based on the design of interfacial chemistry for improving sensitivity, obtaining lower limits of detection (LOD) and enabling the regeneration and reuse of solid-phase QD-FRET hybridization assays. FRET-sensitized emission from acceptor dyes associated with hybridization events at immobilized QD donors provides the analytical signal in these assays. The minimization of active sensing area reduces background from QD donor PL and allows the resolution of smaller amounts of acceptor emission, thus lowering the LOD. The association of multiple acceptor dyes with each hybridization event can enhance FRET efficiency, thereby improving sensitivity. Many previous studies have used interfacial protein layers to generate selectivity; however, transient destabilization of these layers is shown to prevent efficient regeneration. To this end, we report a protein-free interfacial chemistry and demonstrate the specific detection of as little as 2 pmol of target, as well as an improved capacity for regeneration. PMID:22163951