NASA Astrophysics Data System (ADS)
Liang, Guanhao; Wang, Yancheng; Mei, Deqing; Xi, Kailun; Chen, Zichen
2016-04-01
This paper presents an analytical model to study the structural effects of a capacitive tactile sensor array on its capacitance changes and sensitivities. The tactile sensor array has 8 × 8 sensor units, and each unit utilizes the truncated polydimethylsiloxane (PDMS) pyramid array structure as the dielectric layer to enhance the sensing performance. To predict the capacitance changes of the sensor unit, it is simplified into a two-layered structure: upper polyethylene terephthalate (PET) film and bottom truncated PDMS pyramid array. The upper PET is modeled by a displacement field function, while each of the truncated pyramids is analyzed to obtain its stress-strain relation. Using the Ritz method, the displacement field functions are solved. The deformation of the upper electrodes and the capacitance changes of the sensor unit can then be calculated. Using the developed model, the structural effects of the truncated PDMS pyramid array and the PDMS bump on the capacitance changes and sensitivities are studied. To achieve the largest capacitance changes, the dimensions have been optimized for the sensor unit. To verify the developed model, we have fabricated the sensor array, and the average sensitivities of the sensor unit to the x-, y-, and z-axes force are 0.49, 0.50, and 0.32% mN-1, respectively, while the model predicted values are 0.54, 0.54, and 0.35% mN-1. Results demonstrate that the developed model can accurately predict the sensing performance of the sensor array and could be utilized for structural optimization.
An analytic study of near terminal area optimal sequencing and flow control techniques
NASA Technical Reports Server (NTRS)
Park, S. K.; Straeter, T. A.; Hogge, J. E.
1973-01-01
Optimal flow control and sequencing of air traffic operations in the near terminal area are discussed. The near terminal area model is based on the assumptions that the aircraft enter the terminal area along precisely controlled approach paths and that the aircraft are segregated according to their near terminal area performance. Mathematical models are developed to support the optimal path generation, sequencing, and conflict resolution problems.
Analytical and Computational Aspects of Collaborative Optimization
NASA Technical Reports Server (NTRS)
Alexandrov, Natalia M.; Lewis, Robert Michael
2000-01-01
Bilevel problem formulations have received considerable attention as an approach to multidisciplinary optimization in engineering. We examine the analytical and computational properties of one such approach, collaborative optimization. The resulting system-level optimization problems suffer from inherent computational difficulties due to the bilevel nature of the method. Most notably, it is impossible to characterize and hence identify solutions of the system-level problems because the standard first-order conditions for solutions of constrained optimization problems do not hold. The analytical features of the system-level problem make it difficult to apply conventional nonlinear programming algorithms. Simple examples illustrate the analysis and the algorithmic consequences for optimization methods. We conclude with additional observations on the practical implications of the analytical and computational properties of collaborative optimization.
Deco, Gustavo; Hugues, Etienne
2012-01-01
Recent neurophysiological experiments have demonstrated a remarkable effect of attention on the underlying neural activity that suggests for the first time that information encoding is indeed actively influenced by attention. Single cell recordings show that attention reduces both the neural variability and correlations in the attended condition with respect to the non-attended one. This reduction of variability and redundancy enhances the information associated with the detection and further processing of the attended stimulus. Beyond the attentional paradigm, the local activity in a neural circuit can be modulated in a number of ways, leading to the general question of understanding how the activity of such circuits is sensitive to these relatively small modulations. Here, using an analytically tractable neural network model, we demonstrate how this enhancement of information emerges when excitatory and inhibitory synaptic currents are balanced. In particular, we show that the network encoding sensitivity -as measured by the Fisher information- is maximized at the exact balance. Furthermore, we find a similar result for a more realistic spiking neural network model. As the regime of balanced inputs has been experimentally observed, these results suggest that this regime is functionally important from an information encoding standpoint. PMID:22359550
Extended Analytic Device Optimization Employing Asymptotic Expansion
NASA Technical Reports Server (NTRS)
Mackey, Jonathan; Sehirlioglu, Alp; Dynsys, Fred
2013-01-01
Analytic optimization of a thermoelectric junction often introduces several simplifying assumptionsincluding constant material properties, fixed known hot and cold shoe temperatures, and thermallyinsulated leg sides. In fact all of these simplifications will have an effect on device performance,ranging from negligible to significant depending on conditions. Numerical methods, such as FiniteElement Analysis or iterative techniques, are often used to perform more detailed analysis andaccount for these simplifications. While numerical methods may stand as a suitable solution scheme,they are weak in gaining physical understanding and only serve to optimize through iterativesearching techniques. Analytic and asymptotic expansion techniques can be used to solve thegoverning system of thermoelectric differential equations with fewer or less severe assumptionsthan the classic case. Analytic methods can provide meaningful closed form solutions and generatebetter physical understanding of the conditions for when simplifying assumptions may be valid.In obtaining the analytic solutions a set of dimensionless parameters, which characterize allthermoelectric couples, is formulated and provide the limiting cases for validating assumptions.Presentation includes optimization of both classic rectangular couples as well as practically andtheoretically interesting cylindrical couples using optimization parameters physically meaningful toa cylindrical couple. Solutions incorporate the physical behavior for i) thermal resistance of hot andcold shoes, ii) variable material properties with temperature, and iii) lateral heat transfer through legsides.
Analytic solutions for optimal statistical arbitrage trading
NASA Astrophysics Data System (ADS)
Bertram, William K.
2010-06-01
In this paper we derive analytic formulae for statistical arbitrage trading where the security price follows an Ornstein-Uhlenbeck process. By framing the problem in terms of the first-passage time of the process, we derive expressions for the mean and variance of the trade length and the return. We examine the problem of choosing an optimal strategy under two different objective functions: the expected return, and the Sharpe ratio. An exact analytic solution is obtained for the case of maximising the expected return.
Optimism and Physical Health: A Meta-analytic Review
Rasmussen, Heather N.; Greenhouse, Joel B.
2010-01-01
Background Prior research links optimism to physical health, but the strength of the association has not been systematically evaluated. Purpose The purpose of this study is to conduct a meta-analytic review to determine the strength of the association between optimism and physical health. Methods The findings from 83 studies, with 108 effect sizes (ESs), were included in the analyses, using random-effects models. Results Overall, the mean ES characterizing the relationship between optimism and physical health outcomes was 0.17, p<.001. ESs were larger for studies using subjective (versus objective) measures of physical health. Subsidiary analyses were also conducted grouping studies into those that focused solely on mortality, survival, cardiovascular outcomes, physiological markers (including immune function), immune function only, cancer outcomes, outcomes related to pregnancy, physical symptoms, or pain. In each case, optimism was a significant predictor of health outcomes or markers, all p<.001. Conclusions Optimism is a significant predictor of positive physical health outcomes. PMID:19711142
Gradient Optimization for Analytic conTrols - GOAT
NASA Astrophysics Data System (ADS)
Assémat, Elie; Machnes, Shai; Tannor, David; Wilhelm-Mauch, Frank
Quantum optimal control becomes a necessary step in a number of studies in the quantum realm. Recent experimental advances showed that superconducting qubits can be controlled with an impressive accuracy. However, most of the standard optimal control algorithms are not designed to manage such high accuracy. To tackle this issue, a novel quantum optimal control algorithm have been introduced: the Gradient Optimization for Analytic conTrols (GOAT). It avoids the piecewise constant approximation of the control pulse used by standard algorithms. This allows an efficient implementation of very high accuracy optimization. It also includes a novel method to compute the gradient that provides many advantages, e.g. the absence of backpropagation or the natural route to optimize the robustness of the control pulses. This talk will present the GOAT algorithm and a few applications to transmons systems.
NASA Astrophysics Data System (ADS)
Ooi, B. L.; Gilbert, J. M.; Aziz, A. Rashid A.
2016-08-01
Owing to the increasing demand for harvesting energy from environmental vibration for use in self-powered electronic applications, cantilever-based vibration energy harvesting has attracted considerable interest from various parties and has become one of the most common approaches to converting redundant mechanical energy into electrical energy. As the output voltage produced from a piezoelectric material depends largely on the geometric shape and the size of the beam, there is a need to model and compare the performance of cantilever beams of differing geometries. This paper presents the study of strain distribution in various shapes of cantilever beams, including a convex and concave edge profile elliptical beam that have not yet been discussed in any prior literature. Both analytical and finite-element models are derived and the resultant strain distributions in the beam are computed based on a MATLAB solver and ANSYS finite-element analysis tools. An optimum geometry for a vibration-based energy harvesting system is verified. Finally, experimental results comparing the power density for triangular and rectangular piezoelectric beams are also presented to validate the findings of the study, and the claim, as suggested in the literature, is verified.
Using perioperative analytics to optimize OR performance.
Rempfer, Doug
2015-06-01
In the past, the data hospitals gleaned from operating rooms (ORs) tended to be static and lacking in actionable information. Hospitals can improve OR performance by applying OR analytics, such as evaluation of turnover times and expenses, which provide useful intelligence. Having the information is important, but success depends on aligning staff behavior to effectively achieve improvement strategies identified using the analytics.
Optimization of Analytical Potentials for Coarse-Grained Biopolymer Models.
Mereghetti, Paolo; Maccari, Giuseppe; Spampinato, Giulia Lia Beatrice; Tozzini, Valentina
2016-08-25
The increasing trend in the recent literature on coarse grained (CG) models testifies their impact in the study of complex systems. However, the CG model landscape is variegated: even considering a given resolution level, the force fields are very heterogeneous and optimized with very different parametrization procedures. Along the road for standardization of CG models for biopolymers, here we describe a strategy to aid building and optimization of statistics based analytical force fields and its implementation in the software package AsParaGS (Assisted Parameterization platform for coarse Grained modelS). Our method is based on the use and optimization of analytical potentials, optimized by targeting internal variables statistical distributions by means of the combination of different algorithms (i.e., relative entropy driven stochastic exploration of the parameter space and iterative Boltzmann inversion). This allows designing a custom model that endows the force field terms with a physically sound meaning. Furthermore, the level of transferability and accuracy can be tuned through the choice of statistical data set composition. The method-illustrated by means of applications to helical polypeptides-also involves the analysis of two and three variable distributions, and allows handling issues related to the FF term correlations. AsParaGS is interfaced with general-purpose molecular dynamics codes and currently implements the "minimalist" subclass of CG models (i.e., one bead per amino acid, Cα based). Extensions to nucleic acids and different levels of coarse graining are in the course. PMID:27150459
Optimizing an immersion ESL curriculum using analytic hierarchy process.
Tang, Hui-Wen Vivian
2011-11-01
The main purpose of this study is to fill a substantial knowledge gap regarding reaching a uniform group decision in English curriculum design and planning. A comprehensive content-based course criterion model extracted from existing literature and expert opinions was developed. Analytical hierarchy process (AHP) was used to identify the relative importance of course criteria for the purpose of tailoring an optimal one-week immersion English as a second language (ESL) curriculum for elementary school students in a suburban county of Taiwan. The hierarchy model and AHP analysis utilized in the present study will be useful for resolving several important multi-criteria decision-making issues in planning and evaluating ESL programs. This study also offers valuable insights and provides a basis for further research in customizing ESL curriculum models for different student populations with distinct learning needs, goals, and socioeconomic backgrounds.
Analytical Inverse Optimization in Two-Hand Prehensile Tasks.
Parsa, Behnoosh; Ambike, Satyajit; Terekhov, Alexander; Zatsiorsky, Vladimir M; Latash, Mark L
2016-01-01
The authors explored application of analytical inverse optimization (ANIO) method to the normal finger forces in unimanual and bimanual prehensile tasks with discrete and continuously changing constraints. The subjects held an instrumented handle vertically with one or two hands. The external torque and grip force changed across trials or within a trial continuously. Principal component analysis showed similar percentages of variance accounted for by the first two principal components across tasks and conditions. Compared to unimanual tasks, bimanual tasks showed significantly more frequent inability to find a cost function leading to a stable solution. In cases of stable solutions, similar second-order polynomials were computed as cost functions across tasks and condition. The bimanual tasks, however, showed significantly worse goodness-of-fit index values. The authors show that ANIO can be used in tasks with slowly changing constraints making it an attractive tool to study optimality of performance in special populations. They also show that ANIO can fail in multifinger tasks, likely due to irreproducible behavior across trials, more likely to happen in bimanual tasks compared to unimanual tasks.
Analytical Inverse Optimization in Two-Hand Prehensile Tasks.
Parsa, Behnoosh; Ambike, Satyajit; Terekhov, Alexander; Zatsiorsky, Vladimir M; Latash, Mark L
2016-01-01
The authors explored application of analytical inverse optimization (ANIO) method to the normal finger forces in unimanual and bimanual prehensile tasks with discrete and continuously changing constraints. The subjects held an instrumented handle vertically with one or two hands. The external torque and grip force changed across trials or within a trial continuously. Principal component analysis showed similar percentages of variance accounted for by the first two principal components across tasks and conditions. Compared to unimanual tasks, bimanual tasks showed significantly more frequent inability to find a cost function leading to a stable solution. In cases of stable solutions, similar second-order polynomials were computed as cost functions across tasks and condition. The bimanual tasks, however, showed significantly worse goodness-of-fit index values. The authors show that ANIO can be used in tasks with slowly changing constraints making it an attractive tool to study optimality of performance in special populations. They also show that ANIO can fail in multifinger tasks, likely due to irreproducible behavior across trials, more likely to happen in bimanual tasks compared to unimanual tasks. PMID:27254391
Optimal procedures for detecting analytic bias using patient samples.
Smith, F A; Kroft, S H
1997-09-01
We recently described the performance characteristics of the exponentially adjusted moving mean (EAMM), a patient-data, moving block mean procedure, which is a generalized algorithm that unifies Bull's algorithm and the classic average of normals (AON) procedure. Herein we describe the trend EAMM (TEAMM), a continuous signal analog of the EAMM procedure related to classic trend analysis. Using computer simulation, we have compared EAMM and TEAMM over a range of biases for various sample sizes (N or equivalent smoothing factor alpha) and exponential parameters (P) under conditions of equivalent false rejection (fixed on a per patient sample basis). We found optimal pairs of N and P for each level of bias by determination of minimum mean patient samples to rejection. Overall optimal algorithms were determined through calculation of undetected lost medical utility (ULMU), a novel function that quantifies the medical damage due to analytic bias. The ULMU function was calculated based on lost test specificity in a normal population. We found that optimized TEAMM was superior to optimized EAMM for all levels of analytic bias. If these observations hold true for non-Gaussian populations, TEAMM procedures are the method of choice for detecting bias using patient samples or as an event gauge to trigger use of known-value control materials.
Optimization of the firefly luciferase reaction for analytical purposes.
Lundin, Arne
2014-01-01
The optimization of assays has two purposes: (1) to increase the sensitivity of the assay so that low levels of the analyte can be determined; and (2) to prevent small changes of the reaction conditions from having a large impact on the outcome of the assay. The two purposes are usually equally important, as has been recognized in well-established branches of analytical chemistry, such as clinical chemistry. The firefly luciferase reaction can be used for many types of assays. The way to optimize these assays is not trivial, as there are many parameters to consider. Furthermore, as there are now several types of recombinant luciferases available, one has to decide which is the most suitable for each individual assay. The optimization is influenced by the conditions and requirements under which the assay is performed. Special attention is given to ways to calibrate assays. Examples on optimization are mainly taken from the author's own work during 40 years using assays based on the firefly luciferase reaction.
Roll levelling semi-analytical model for process optimization
NASA Astrophysics Data System (ADS)
Silvestre, E.; Garcia, D.; Galdos, L.; Saenz de Argandoña, E.; Mendiguren, J.
2016-08-01
Roll levelling is a primary manufacturing process used to remove residual stresses and imperfections of metal strips in order to make them suitable for subsequent forming operations. In the last years the importance of this process has been evidenced with the apparition of Ultra High Strength Steels with strength > 900 MPa. The optimal setting of the machine as well as a robust machine design has become critical for the correct processing of these materials. Finite Element Method (FEM) analysis is the widely used technique for both aspects. However, in this case, the FEM simulation times are above the admissible ones in both machine development and process optimization. In the present work, a semi-analytical model based on a discrete bending theory is presented. This model is able to calculate the critical levelling parameters i.e. force, plastification rate, residual stresses in a few seconds. First the semi-analytical model is presented. Next, some experimental industrial cases are analyzed by both the semi-analytical model and the conventional FEM model. Finally, results and computation times of both methods are compared.
Statistical and optimal learning with applications in business analytics
NASA Astrophysics Data System (ADS)
Han, Bin
Statistical learning is widely used in business analytics to discover structure or exploit patterns from historical data, and build models that capture relationships between an outcome of interest and a set of variables. Optimal learning on the other hand, solves the operational side of the problem, by iterating between decision making and data acquisition/learning. All too often the two problems go hand-in-hand, which exhibit a feedback loop between statistics and optimization. We apply this statistical/optimal learning concept on a context of fundraising marketing campaign problem arising in many non-profit organizations. Many such organizations use direct-mail marketing to cultivate one-time donors and convert them into recurring contributors. Cultivated donors generate much more revenue than new donors, but also lapse with time, making it important to steadily draw in new cultivations. The direct-mail budget is limited, but better-designed mailings can improve success rates without increasing costs. We first apply statistical learning to analyze the effectiveness of several design approaches used in practice, based on a massive dataset covering 8.6 million direct-mail communications with donors to the American Red Cross during 2009-2011. We find evidence that mailed appeals are more effective when they emphasize disaster preparedness and training efforts over post-disaster cleanup. Including small cards that affirm donors' identity as Red Cross supporters is an effective strategy, while including gift items such as address labels is not. Finally, very recent acquisitions are more likely to respond to appeals that ask them to contribute an amount similar to their most recent donation, but this approach has an adverse effect on donors with a longer history. We show via simulation that a simple design strategy based on these insights has potential to improve success rates from 5.4% to 8.1%. Given these findings, when new scenario arises, however, new data need to
Analytical investigations in aircraft and spacecraft trajectory optimization and optimal guidance
NASA Technical Reports Server (NTRS)
Markopoulos, Nikos; Calise, Anthony J.
1995-01-01
A collection of analytical studies is presented related to unconstrained and constrained aircraft (a/c) energy-state modeling and to spacecraft (s/c) motion under continuous thrust. With regard to a/c unconstrained energy-state modeling, the physical origin of the singular perturbation parameter that accounts for the observed 2-time-scale behavior of a/c during energy climbs is identified and explained. With regard to the constrained energy-state modeling, optimal control problems are studied involving active state-variable inequality constraints. Departing from the practical deficiencies of the control programs for such problems that result from the traditional formulations, a complete reformulation is proposed for these problems which, in contrast to the old formulation, will presumably lead to practically useful controllers that can track an inequality constraint boundary asymptotically, and even in the presence of 2-sided perturbations about it. Finally, with regard to s/c motion under continuous thrust, a thrust program is proposed for which the equations of 2-dimensional motion of a space vehicle in orbit, viewed as a point mass, afford an exact analytic solution. The thrust program arises under the assumption of tangential thrust from the costate system corresponding to minimum-fuel, power-limited, coplanar transfers between two arbitrary conics. The thrust program can be used not only with power-limited propulsion systems, but also with any propulsion system capable of generating continuous thrust of controllable magnitude, and, for propulsion types and classes of transfers for which it is sufficiently optimal the results of this report suggest a method of maneuvering during planetocentric or heliocentric orbital operations, requiring a minimum amount of computation; thus uniquely suitable for real-time feedback guidance implementations.
Optimization of the analytical extraction of polyamines from milk.
Rigueira, Juliana Cristina Sampaio; Rodrigues, Maria Isabel; Gloria, Maria Beatriz Abreu
2011-10-30
Polyamines play an important role as growth promoters, in the maturation of the intestinal tract of infants and in the modulation of the immune response; consequently, the importance of polyamines in the diet of infants and adults is well established. However, information on the occurrence and levels of polyamines in cow's milk and milk from other species (including human milk) is contradictory. Furthermore, the methods used for the extraction of amines from these samples vary widely. Therefore, a method for the accurate analysis of amines in milk from different species and in milk products is needed. A sequential strategy of experimental designs was used to optimize the analytical extraction of polyamines from milk. The dependent variables that significantly affected the recoveries were screened through a Plackett-Burman design. Sulfosalicylic acid (SSA) provided better recoveries compared to trichloroacetic acid. Centrifugation time and speed during extraction were independent variables. The Central Composite Rotational Design used to optimize the dependent variables indicated that the optimal conditions for the extraction of polyamines were 40s vortexing, four successive extractions, and an SSA concentration of 1.5%. These conditions provided recoveries ≥ 92.8% and CV ≤ 5.8%. The experiments confirmed the predicted results, indicating that the optimized conditions and models used were effective in the determination of amines from milk. Samples of raw milk and milk beverages were observed to be poor sources of spermine and spermidine, whereas human milk contained both amines.
The analytical representation of viscoelastic material properties using optimization techniques
NASA Astrophysics Data System (ADS)
Hill, S. A.
1993-02-01
This report presents a technique to model viscoelastic material properties with a function of the form of the Prony series. Generally, the method employed to determine the function constants requires assuming values for the exponential constants of the function and then resolving the remaining constants through linear least-squares techniques. The technique presented here allows all the constants to be analytically determined through optimization techniques. This technique is employed in a computer program named PRONY and makes use of commercially available optimization tool developed by VMA Engineering, Inc. The PRONY program was utilized to compare the technique against previously determined models for solid rocket motor TP-H1148 propellant and V747-75 Viton fluoroelastomer. In both cases, the optimization technique generated functions that modeled the test data with at least an order of magnitude better correlation. This technique has demonstrated the capability to use small or large data sets and to use data sets that have uniformly or nonuniformly spaced data pairs. The reduction of experimental data to accurate mathematical models is a vital part of most scientific and engineering research. This technique of regression through optimization can be applied to other mathematical models that are difficult to fit to experimental data through traditional regression techniques.
Optimizing an Immersion ESL Curriculum Using Analytic Hierarchy Process
ERIC Educational Resources Information Center
Tang, Hui-Wen Vivian
2011-01-01
The main purpose of this study is to fill a substantial knowledge gap regarding reaching a uniform group decision in English curriculum design and planning. A comprehensive content-based course criterion model extracted from existing literature and expert opinions was developed. Analytical hierarchy process (AHP) was used to identify the relative…
Stochastic Optimization for an Analytical Model of Saltwater Intrusion in Coastal Aquifers
Stratis, Paris N.; Karatzas, George P.; Papadopoulou, Elena P.; Zakynthinaki, Maria S.; Saridakis, Yiannis G.
2016-01-01
The present study implements a stochastic optimization technique to optimally manage freshwater pumping from coastal aquifers. Our simulations utilize the well-known sharp interface model for saltwater intrusion in coastal aquifers together with its known analytical solution. The objective is to maximize the total volume of freshwater pumped by the wells from the aquifer while, at the same time, protecting the aquifer from saltwater intrusion. In the direction of dealing with this problem in real time, the ALOPEX stochastic optimization method is used, to optimize the pumping rates of the wells, coupled with a penalty-based strategy that keeps the saltwater front at a safe distance from the wells. Several numerical optimization results, that simulate a known real aquifer case, are presented. The results explore the computational performance of the chosen stochastic optimization method as well as its abilities to manage freshwater pumping in real aquifer environments. PMID:27689362
Analytical insights into optimality and resonance in fish swimming
Kohannim, Saba; Iwasaki, Tetsuya
2014-01-01
This paper provides analytical insights into the hypothesis that fish exploit resonance to reduce the mechanical cost of swimming. A simple body–fluid fish model, representing carangiform locomotion, is developed. Steady swimming at various speeds is analysed using optimal gait theory by minimizing bending moment over tail movements and stiffness, and the results are shown to match with data from observed swimming. Our analysis indicates the following: thrust–drag balance leads to the Strouhal number being predetermined based on the drag coefficient and the ratio of wetted body area to cross-sectional area of accelerated fluid. Muscle tension is reduced when undulation frequency matches resonance frequency, which maximizes the ratio of tail-tip velocity to bending moment. Finally, hydrodynamic resonance determines tail-beat frequency, whereas muscle stiffness is actively adjusted, so that overall body–fluid resonance is exploited. PMID:24430125
An analytic approach to optimize tidal turbine fields
NASA Astrophysics Data System (ADS)
Pelz, P.; Metzler, M.
2013-12-01
Motivated by global warming due to CO2-emission various technologies for harvesting of energy from renewable sources are developed. Hydrokinetic turbines get applied to surface watercourse or tidal flow to gain electrical energy. Since the available power for hydrokinetic turbines is proportional to the projected cross section area, fields of turbines are installed to scale shaft power. Each hydrokinetic turbine of a field can be considered as a disk actuator. In [1], the first author derives the optimal operation point for hydropower in an open-channel. The present paper concerns about a 0-dimensional model of a disk-actuator in an open-channel flow with bypass, as a special case of [1]. Based on the energy equation, the continuity equation and the momentum balance an analytical approach is made to calculate the coefficient of performance for hydrokinetic turbines with bypass flow as function of the turbine head and the ratio of turbine width to channel width.
Analytical Dimensional Reduction of a Fuel Optimal Powered Descent Subproblem
NASA Technical Reports Server (NTRS)
Rea, Jeremy R.; Bishop, Robert H.
2010-01-01
Current renewed interest in exploration of the moon, Mars, and other planetary objects is driving technology development in many fields of space system design. In particular, there is a desire to land both robotic and human missions on the moon and elsewhere. The landing guidance system must be able to deliver the vehicle to a desired soft landing while meeting several constraints necessary for the safety of the vehicle. Due to performance limitations of current launch vehicles, it is desired to minimize the amount of fuel used. In addition, the landing site may change in real-time in order to avoid previously undetected hazards which become apparent during the landing maneuver. This complicated maneuver can be broken into simpler subproblems that bound the full problem. One such subproblem is to find a minimum-fuel landing solution that meets constraints on the initial state, final state, and bounded thrust acceleration magnitude. With the assumptions of constant gravity and negligible atmosphere, the form of the optimal steering law is known, and the equations of motion can be integrated analytically, resulting in a system of five equations in five unknowns. It is shown that this system of equations can be reduced analytically to two equations in two unknowns. With an additional assumption of constant thrust acceleration magnitude, this system can be reduced further to one equation in one unknown. It is shown that these unknowns can be bounded analytically. An algorithm is developed to quickly and reliably solve the resulting one-dimensional bounded search, and it is used as a real-time guidance applied to a lunar landing test case.
Błażewicz, Anna; Klatka, Maria; Dolliver, Wojciech; Kocjan, Ryszard
2014-07-01
A fast, accurate and precise ion chromatography method with pulsed amperometric detection was applied to evaluate a variety of parameters affecting the determination of total iodine in serum and urine of 81 subjects, including 56 obese and 25 healthy Polish children. The sample pretreatment methods were carried out in a closed system and with the assistance of microwaves. Both alkaline and acidic digestion procedures were developed and optimized to find the simplest combination of reagents and the appropriate parameters for digestion that would allow for the fastest, least time consuming and most cost-effective way of analysis. A good correlation between the certified and the measured concentrations was achieved. The best recoveries (96.8% for urine and 98.8% for serum samples) were achieved using 1ml of 25% tetramethylammonium hydroxide solution within 6min for 0.1ml of serum/urine samples. Using 0.5ml of 65% nitric acid solution the best recovery (95.3%) was obtained when 7min of effective digestion time was used. Freeze-thaw stability and long-term stability were checked. After 24 weeks 14.7% loss of iodine in urine, and 10.9% in serum samples occurred. For urine samples, better correlation (R(2)=0.9891) of various sample preparation procedures (alkaline digestion and application of OnGuard RP cartidges) was obtained. Significantly lower iodide content was found in samples taken from obese children. Serum iodine content in obese children was markedly variable in comparison with the healthy group, whereas the difference was less evident when urine samples were analyzed. The mean content in serum was 59.12±8.86μg/L, and in urine 98.26±25.93 for obese children when samples were prepared by the use of optimized alkaline digestion reinforced by microwaves. In healthy children the mean content in serum was 82.58±6.01μg/L, and in urine 145.76±31.44μg/L.
Laser: a Tool for Optimization and Enhancement of Analytical Methods
Preisler, Jan
1997-01-01
In this work, we use lasers to enhance possibilities of laser desorption methods and to optimize coating procedure for capillary electrophoresis (CE). We use several different instrumental arrangements to characterize matrix-assisted laser desorption (MALD) at atmospheric pressure and in vacuum. In imaging mode, 488-nm argon-ion laser beam is deflected by two acousto-optic deflectors to scan plumes desorbed at atmospheric pressure via absorption. All absorbing species, including neutral molecules, are monitored. Interesting features, e.g. differences between the initial plume and subsequent plumes desorbed from the same spot, or the formation of two plumes from one laser shot are observed. Total plume absorbance can be correlated with the acoustic signal generated by the desorption event. A model equation for the plume velocity as a function of time is proposed. Alternatively, the use of a static laser beam for observation enables reliable determination of plume velocities even when they are very high. Static scattering detection reveals negative influence of particle spallation on MS signal. Ion formation during MALD was monitored using 193-nm light to photodissociate a portion of insulin ion plume. These results define the optimal conditions for desorbing analytes from matrices, as opposed to achieving a compromise between efficient desorption and efficient ionization as is practiced in mass spectrometry. In CE experiment, we examined changes in a poly(ethylene oxide) (PEO) coating by continuously monitoring the electroosmotic flow (EOF) in a fused-silica capillary during electrophoresis. An imaging CCD camera was used to follow the motion of a fluorescent neutral marker zone along the length of the capillary excited by 488-nm Ar-ion laser. The PEO coating was shown to reduce the velocity of EOF by more than an order of magnitude compared to a bare capillary at pH 7.0. The coating protocol was important, especially at an intermediate pH of 7.7. The increase of p
A. S. Hofler; P. Evtushenko; M. Krasilnikov
2007-08-01
Injector gun design is an iterative process where the designer optimizes a few nonlinearly interdependent beam parameters to achieve the required beam quality for a particle accelerator. Few tools exist to automate the optimization process and thoroughly explore the parameter space. The challenging beam requirements of new accelerator applications such as light sources and electron cooling devices drive the development of RF and SRF photo injectors. RF and SRF gun design is further complicated because the bunches are space charge dominated and require additional emittance compensation. A genetic algorithm has been successfully used to optimize DC photo injector designs for Cornell* and Jefferson Lab**, and we propose studying how the genetic algorithm techniques can be applied to the design of RF and SRF gun injectors. In this paper, we report on the initial phase of the study where we model and optimize gun designs that have been benchmarked with beam measurements and simulation.
Kawase, Mitsuhiro
2009-11-22
The zipped file contains a directory of data and routines used in the NNMREC turbine depth optimization study (Kawase et al., 2011), and calculation results thereof. For further info, please contact Mitsuhiro Kawase at kawase@uw.edu. Reference: Mitsuhiro Kawase, Patricia Beba, and Brian Fabien (2011), Finding an Optimal Placement Depth for a Tidal In-Stream Conversion Device in an Energetic, Baroclinic Tidal Channel, NNMREC Technical Report.
Alicia Hofler; Pavel Evtushenko
2007-07-03
Injector gun design is an iterative process where the designer optimizes a few nonlinearly interdependent beam parameters to achieve the required beam quality for a particle accelerator. Few tools exist to automate the optimization process and thoroughly explore the parameter space. The challenging beam requirements of new accelerator applications such as light sources and electron cooling devices drive the development of RF and SRF photo injectors. A genetic algorithm (GA) has been successfully used to optimize DC photo injector designs at Cornell University [1] and Jefferson Lab [2]. We propose to apply GA techniques to the design of RF and SRF gun injectors. In this paper, we report on the initial phase of the study where we model and optimize a system that has been benchmarked with beam measurements and simulation.
Meeks, S L; Bova, F J; Buatti, J M; Friedman, W A; Eyster, B; Kendrick, L A
1999-11-01
Linear accelerator (linac) radiosurgery utilizes non-coplanar arc therapy delivered through circular collimators. Generally, spherically symmetric arc sets are used, resulting in nominally spherical dose distributions. Various treatment planning parameters may be manipulated to provide dose conformation to irregular lesions. Iterative manipulation of these variables can be a difficult and time-consuming task, because (a) understanding the effect of these parameters is complicated and (b) three-dimensional (3D) dose calculations are computationally expensive. This manipulation can be simplified, however, because the prescription isodose surface for all single isocentre distributions can be approximated by conic sections. In this study, the effects of treatment planning parameter manipulation on the dimensions of the treatment isodose surface were determined empirically. These dimensions were then fitted to analytic functions, assuming that the dose distributions were characterized as conic sections. These analytic functions allowed real-time approximation of the 3D isodose surface. Iterative plan optimization, either manual or automated, is achieved more efficiently using this real time approximation of the dose matrix. Subsequent to iterative plan optimization, the analytic function is related back to the appropriate plan parameters, and the dose distribution is determined using conventional dosimetry calculations. This provides a pseudo-inverse approach to radiosurgery optimization, based solely on geometric considerations.
Optimal symmetric flight studies
NASA Technical Reports Server (NTRS)
Weston, A. R.; Menon, P. K. A.; Bilimoria, K. D.; Cliff, E. M.; Kelley, H. J.
1985-01-01
Several topics in optimal symmetric flight of airbreathing vehicles are examined. In one study, an approximation scheme designed for onboard real-time energy management of climb-dash is developed and calculations for a high-performance aircraft presented. In another, a vehicle model intermediate in complexity between energy and point-mass models is explored and some quirks in optimal flight characteristics peculiar to the model uncovered. In yet another study, energy-modelling procedures are re-examined with a view to stretching the range of validity of zeroth-order approximation by special choice of state variables. In a final study, time-fuel tradeoffs in cruise-dash are examined for the consequences of nonconvexities appearing in the classical steady cruise-dash model. Two appendices provide retrospective looks at two early publications on energy modelling and related optimal control theory.
Analytical and experimental study of resonance ignition tubes
NASA Technical Reports Server (NTRS)
Stabinsky, L.
1973-01-01
The application of the gas-dynamic resonance concept was investigated in relation to ignition of rocket propulsion systems. Analytical studies were conducted to delineate the potential uses of resonance ignition in oxygen/hydrogen bipropellant and hydrazine monopropellant rocket engines. Experimental studies were made to: (1) optimize the resonance igniter configuration, and (2) evaluate the ignition characteristics when operating with low temperature oxygen and hydrogen at the inlet to the igniter.
Analytical studies of coherent electron cooling
Wang,G.; Blaskiewicz, M.; Litvinenko, V.N.
2009-05-04
Under certain assumptions and simplifications, we studied a few physics processes of Coherent Electron Cooling using analytical approach. In the modulation process, the effect due to merging the ion beam with the electron beam is studied under single kick approximation. In the free electron laser (FEL) amplifier, we studied the amplification of the electron density modulation using 1D analytical approach. Both the electron charge density and the phase space density are derived in the frequency domain. The solutions are then transformed into the space domain through Fast Fourier Transformation (FFT).
Optimal analytic method for the nonlinear Hasegawa-Mima equation
NASA Astrophysics Data System (ADS)
Baxter, Mathew; Van Gorder, Robert A.; Vajravelu, Kuppalapalle
2014-05-01
The Hasegawa-Mima equation is a nonlinear partial differential equation that describes the electric potential due to a drift wave in a plasma. In the present paper, we apply the method of homotopy analysis to a slightly more general Hasegawa-Mima equation, which accounts for hyper-viscous damping or viscous dissipation. First, we outline the method for the general initial/boundary value problem over a compact rectangular spatial domain. We use a two-stage method, where both the convergence control parameter and the auxiliary linear operator are optimally selected to minimize the residual error due to the approximation. To do the latter, we consider a family of operators parameterized by a constant which gives the decay rate of the solutions. After outlining the general method, we consider a number of concrete examples in order to demonstrate the utility of this approach. The results enable us to study properties of the initial/boundary value problem for the generalized Hasegawa-Mima equation. In several cases considered, we are able to obtain solutions with extremely small residual errors after relatively few iterations are computed (residual errors on the order of 10-15 are found in multiple cases after only three iterations). The results demonstrate that selecting a parameterized auxiliary linear operator can be extremely useful for minimizing residual errors when used concurrently with the optimal homotopy analysis method, suggesting that this approach can prove useful for a number of nonlinear partial differential equations arising in physics and nonlinear mechanics.
Ponslet, E.R.; Eldred, M.S.
1996-05-17
An analytical and experimental study is conducted to investigate the effect of isolator locations on the effectiveness of vibration isolation systems. The study uses isolators with fixed properties and evaluates potential improvements to the isolation system that can be achieved by optimizing isolator locations. Because the available locations for the isolators are discrete in this application, a Genetic Algorithm (GA) is used as the optimization method. The system is modeled in MATLAB{trademark} and coupled with the GA available in the DAKOTA optimization toolkit under development at Sandia National Laboratories. Design constraints dictated by hardware and experimental limitations are implemented through penalty function techniques. A series of GA runs reveal difficulties in the search on this heavily constrained, multimodal, discrete problem. However, the GA runs provide a variety of optimized designs with predicted performance from 30 to 70 times better than a baseline configuration. An alternate approach is also tested on this problem: it uses continuous optimization, followed by rounding of the solution to neighboring discrete configurations. Results show that this approach leads to either infeasible or poor designs. Finally, a number of optimized designs obtained from the GA searches are tested in the laboratory and compared to the baseline design. These experimental results show a 7 to 46 times improvement in vibration isolation from the baseline configuration.
Recent Studies in Functional Analytic Psychotherapy
ERIC Educational Resources Information Center
Garcia, Rafael Ferro
2008-01-01
Functional Analytic Psychotherapy (FAP), based on the principles of radical behaviorism, emphasizes the impact of eventualities that occur during therapeutic sessions, the therapist-client interaction context, functional equivalence between environments, natural reinforcement and shaping by the therapist. This paper reviews recent studies of FAP…
Heliostat cost optimization study
NASA Astrophysics Data System (ADS)
von Reeken, Finn; Weinrebe, Gerhard; Keck, Thomas; Balz, Markus
2016-05-01
This paper presents a methodology for a heliostat cost optimization study. First different variants of small, medium sized and large heliostats are designed. Then the respective costs, tracking and optical quality are determined. For the calculation of optical quality a structural model of the heliostat is programmed and analyzed using finite element software. The costs are determined based on inquiries and from experience with similar structures. Eventually the levelised electricity costs for a reference power tower plant are calculated. Before each annual simulation run the heliostat field is optimized. Calculated LCOEs are then used to identify the most suitable option(s). Finally, the conclusions and findings of this extensive cost study are used to define the concept of a new cost-efficient heliostat called `Stellio'.
Query optimization for graph analytics on linked data using SPARQL
Hong, Seokyong; Lee, Sangkeun; Lim, Seung -Hwan; Sukumar, Sreenivas R.; Vatsavai, Ranga Raju
2015-07-01
Triplestores that support query languages such as SPARQL are emerging as the preferred and scalable solution to represent data and meta-data as massive heterogeneous graphs using Semantic Web standards. With increasing adoption, the desire to conduct graph-theoretic mining and exploratory analysis has also increased. Addressing that desire, this paper presents a solution that is the marriage of Graph Theory and the Semantic Web. We present software that can analyze Linked Data using graph operations such as counting triangles, finding eccentricity, testing connectedness, and computing PageRank directly on triple stores via the SPARQL interface. We describe the process of optimizing performance of the SPARQL-based implementation of such popular graph algorithms by reducing the space-overhead, simplifying iterative complexity and removing redundant computations by understanding query plans. Our optimized approach shows significant performance gains on triplestores hosted on stand-alone workstations as well as hardware-optimized scalable supercomputers such as the Cray XMT.
Truzzi, Cristina; Annibaldi, Anna; Illuminati, Silvia; Finale, Carolina; Scarponi, Giuseppe
2014-05-01
The study compares official spectrophotometric methods for the determination of proline content in honey - those of the International Honey Commission (IHC) and the Association of Official Analytical Chemists (AOAC) - with the original Ough method. Results show that the extra time-consuming treatment stages added by the IHC method with respect to the Ough method are pointless. We demonstrate that the AOACs method proves to be the best in terms of accuracy and time saving. The optimized waiting time for the absorbance recording is set at 35min from the removal of reaction tubes from the boiling bath used in the sample treatment. The optimized method was validated in the matrix: linearity up to 1800mgL(-1), limit of detection 20mgL(-1), limit of quantification 61mgL(-1). The method was applied to 43 unifloral honey samples from the Marche region, Italy.
Truzzi, Cristina; Annibaldi, Anna; Illuminati, Silvia; Finale, Carolina; Scarponi, Giuseppe
2014-05-01
The study compares official spectrophotometric methods for the determination of proline content in honey - those of the International Honey Commission (IHC) and the Association of Official Analytical Chemists (AOAC) - with the original Ough method. Results show that the extra time-consuming treatment stages added by the IHC method with respect to the Ough method are pointless. We demonstrate that the AOACs method proves to be the best in terms of accuracy and time saving. The optimized waiting time for the absorbance recording is set at 35min from the removal of reaction tubes from the boiling bath used in the sample treatment. The optimized method was validated in the matrix: linearity up to 1800mgL(-1), limit of detection 20mgL(-1), limit of quantification 61mgL(-1). The method was applied to 43 unifloral honey samples from the Marche region, Italy. PMID:24360478
Analytical models integrated with satellite images for optimized pest management
Technology Transfer Automated Retrieval System (TEKTRAN)
The global field protection (GFP) was developed to protect and optimize pest management resources integrating satellite images for precise field demarcation with physical models of controlled release devices of pesticides to protect large fields. The GFP was implemented using a graphical user interf...
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.
Ahn, Yongjun; Yeo, Hwasoo
2015-01-01
The charging infrastructure location problem is becoming more significant due to the extensive adoption of electric vehicles. Efficient charging station planning can solve deeply rooted problems, such as driving-range anxiety and the stagnation of new electric vehicle consumers. In the initial stage of introducing electric vehicles, the allocation of charging stations is difficult to determine due to the uncertainty of candidate sites and unidentified charging demands, which are determined by diverse variables. This paper introduces the Estimating the Required Density of EV Charging (ERDEC) stations model, which is an analytical approach to estimating the optimal density of charging stations for certain urban areas, which are subsequently aggregated to city level planning. The optimal charging station's density is derived to minimize the total cost. A numerical study is conducted to obtain the correlations among the various parameters in the proposed model, such as regional parameters, technological parameters and coefficient factors. To investigate the effect of technological advances, the corresponding changes in the optimal density and total cost are also examined by various combinations of technological parameters. Daejeon city in South Korea is selected for the case study to examine the applicability of the model to real-world problems. With real taxi trajectory data, the optimal density map of charging stations is generated. These results can provide the optimal number of chargers for driving without driving-range anxiety. In the initial planning phase of installing charging infrastructure, the proposed model can be applied to a relatively extensive area to encourage the usage of electric vehicles, especially areas that lack information, such as exact candidate sites for charging stations and other data related with electric vehicles. The methods and results of this paper can serve as a planning guideline to facilitate the extensive adoption of electric
Ahn, Yongjun; Yeo, Hwasoo
2015-01-01
The charging infrastructure location problem is becoming more significant due to the extensive adoption of electric vehicles. Efficient charging station planning can solve deeply rooted problems, such as driving-range anxiety and the stagnation of new electric vehicle consumers. In the initial stage of introducing electric vehicles, the allocation of charging stations is difficult to determine due to the uncertainty of candidate sites and unidentified charging demands, which are determined by diverse variables. This paper introduces the Estimating the Required Density of EV Charging (ERDEC) stations model, which is an analytical approach to estimating the optimal density of charging stations for certain urban areas, which are subsequently aggregated to city level planning. The optimal charging station’s density is derived to minimize the total cost. A numerical study is conducted to obtain the correlations among the various parameters in the proposed model, such as regional parameters, technological parameters and coefficient factors. To investigate the effect of technological advances, the corresponding changes in the optimal density and total cost are also examined by various combinations of technological parameters. Daejeon city in South Korea is selected for the case study to examine the applicability of the model to real-world problems. With real taxi trajectory data, the optimal density map of charging stations is generated. These results can provide the optimal number of chargers for driving without driving-range anxiety. In the initial planning phase of installing charging infrastructure, the proposed model can be applied to a relatively extensive area to encourage the usage of electric vehicles, especially areas that lack information, such as exact candidate sites for charging stations and other data related with electric vehicles. The methods and results of this paper can serve as a planning guideline to facilitate the extensive adoption of electric
Ahn, Yongjun; Yeo, Hwasoo
2015-01-01
The charging infrastructure location problem is becoming more significant due to the extensive adoption of electric vehicles. Efficient charging station planning can solve deeply rooted problems, such as driving-range anxiety and the stagnation of new electric vehicle consumers. In the initial stage of introducing electric vehicles, the allocation of charging stations is difficult to determine due to the uncertainty of candidate sites and unidentified charging demands, which are determined by diverse variables. This paper introduces the Estimating the Required Density of EV Charging (ERDEC) stations model, which is an analytical approach to estimating the optimal density of charging stations for certain urban areas, which are subsequently aggregated to city level planning. The optimal charging station's density is derived to minimize the total cost. A numerical study is conducted to obtain the correlations among the various parameters in the proposed model, such as regional parameters, technological parameters and coefficient factors. To investigate the effect of technological advances, the corresponding changes in the optimal density and total cost are also examined by various combinations of technological parameters. Daejeon city in South Korea is selected for the case study to examine the applicability of the model to real-world problems. With real taxi trajectory data, the optimal density map of charging stations is generated. These results can provide the optimal number of chargers for driving without driving-range anxiety. In the initial planning phase of installing charging infrastructure, the proposed model can be applied to a relatively extensive area to encourage the usage of electric vehicles, especially areas that lack information, such as exact candidate sites for charging stations and other data related with electric vehicles. The methods and results of this paper can serve as a planning guideline to facilitate the extensive adoption of electric
Candioti, Luciana Vera; De Zan, María M; Cámara, María S; Goicoechea, Héctor C
2014-06-01
A review about the application of response surface methodology (RSM) when several responses have to be simultaneously optimized in the field of analytical methods development is presented. Several critical issues like response transformation, multiple response optimization and modeling with least squares and artificial neural networks are discussed. Most recent analytical applications are presented in the context of analytLaboratorio de Control de Calidad de Medicamentos (LCCM), Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, C.C. 242, S3000ZAA Santa Fe, ArgentinaLaboratorio de Control de Calidad de Medicamentos (LCCM), Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, C.C. 242, S3000ZAA Santa Fe, Argentinaical methods development, especially in multiple response optimization procedures using the desirability function.
Sweeping Jet Optimization Studies
NASA Technical Reports Server (NTRS)
Melton, LaTunia Pack; Koklu, Mehti; Andino, Marlyn; Lin, John C.; Edelman, Louis
2016-01-01
Progress on experimental efforts to optimize sweeping jet actuators for active flow control (AFC) applications with large adverse pressure gradients is reported. Three sweeping jet actuator configurations, with the same orifice size but di?erent internal geometries, were installed on the flap shoulder of an unswept, NACA 0015 semi-span wing to investigate how the output produced by a sweeping jet interacts with the separated flow and the mechanisms by which the flow separation is controlled. For this experiment, the flow separation was generated by deflecting the wing's 30% chord trailing edge flap to produce an adverse pressure gradient. Steady and unsteady pressure data, Particle Image Velocimetry data, and force and moment data were acquired to assess the performance of the three actuator configurations. The actuator with the largest jet deflection angle, at the pressure ratios investigated, was the most efficient at controlling flow separation on the flap of the model. Oil flow visualization studies revealed that the flow field controlled by the sweeping jets was more three-dimensional than expected. The results presented also show that the actuator spacing was appropriate for the pressure ratios examined.
Analytical and experimental performance of optimal controller designs for a supersonic inlet
NASA Technical Reports Server (NTRS)
Zeller, J. R.; Lehtinen, B.; Geyser, L. C.; Batterton, P. G.
1973-01-01
The techniques of modern optimal control theory were applied to the design of a control system for a supersonic inlet. The inlet control problem was approached as a linear stochastic optimal control problem using as the performance index the expected frequency of unstarts. The details of the formulation of the stochastic inlet control problem are presented. The computational procedures required to obtain optimal controller designs are discussed, and the analytically predicted performance of controllers designed for several different inlet conditions is tabulated. The experimental implementation of the optimal control laws is described, and the experimental results obtained in a supersonic wind tunnel are presented. The control laws were implemented with analog and digital computers. Comparisons are made between the experimental and analytically predicted performance results. Comparisons are also made between the results obtained with continuous analog computer controllers and discrete digital computer versions.
Analytical and Experimental Studies on Fixtured Work pieces
NASA Astrophysics Data System (ADS)
Nagendran, Latha; Srinivasan, K.; Ranjeev, V.
2004-06-01
An important aspect in the design of a good fixture is that of imparting sufficient rigidity to all the work piece surfaces that are to be machined. Work piece deformation during fixture set-up and process operation is the most important consideration in the fixture design process. The present work aims at studying the effect of cutting forces and clamping forces on the workpiece. Prediction of deflection of the part under cutting loads and obtaining an optimal fix ture configuration could eliminate part rejects attributed to poor fixture design. The results of an analytical study to optimize the position of locators and clamps using a three stage procedure based on the Finite Element method is presented here. In the first stage, the optimal position for the base locators is determined with the objective being that of minimizing the deflection of the work piece. In the second stage, the position of the clamps and side locators and in the third stage, the clamping forces have been optimized. The work piece has been considered as a deformable body and the fixture elements as rigid members. Contact between the fixture elements and the work piece has been modeled using surface- to- surface contact elements and Coulomb friction assumed between contact surfaces. The deflection predicted by the analysis for various configurations of the base locators has been compared with the values that have been obtained experimentally using a test fixture. The results from the analysis and experiment follow the same trend and are comparable.
Asymptotic Linearity of Optimal Control Modification Adaptive Law with Analytical Stability Margins
NASA Technical Reports Server (NTRS)
Nguyen, Nhan T.
2010-01-01
Optimal control modification has been developed to improve robustness to model-reference adaptive control. For systems with linear matched uncertainty, optimal control modification adaptive law can be shown by a singular perturbation argument to possess an outer solution that exhibits a linear asymptotic property. Analytical expressions of phase and time delay margins for the outer solution can be obtained. Using the gradient projection operator, a free design parameter of the adaptive law can be selected to satisfy stability margins.
Căruntu, Bogdan
2014-01-01
The paper presents the optimal homotopy perturbation method, which is a new method to find approximate analytical solutions for nonlinear partial differential equations. Based on the well-known homotopy perturbation method, the optimal homotopy perturbation method presents an accelerated convergence compared to the regular homotopy perturbation method. The applications presented emphasize the high accuracy of the method by means of a comparison with previous results. PMID:25003150
Nuclear analytical techniques in environmental studies.
Jervis, R E
1994-01-01
Nuclear analytical techniques are particularly suitable for measuring trace components in a wide variety of environmental samples, and for that reason, the techniques have made a significant contribution to environmental research. Presently, at a time when biosphere contamination and threats of global change in the atmosphere are of widespread concern, there exist an impressive array of specialized instrumental methods available to life scientists engaged in environmental studies; however, the nuclear techniques will probably continue to play a useful role in the future, notwithstanding the decreasing availability of necessary facilities, such as research reactors and accelerators. Reasons for the particular suitability of radionanalytical techniques are reviewed and illustrated by examples of recent applications to solid wastes, biomonitoring, and urban aerosol source identification in this laboratory.
Hubert, C; Houari, S; Rozet, E; Lebrun, P; Hubert, Ph
2015-05-22
When using an analytical method, defining an analytical target profile (ATP) focused on quantitative performance represents a key input, and this will drive the method development process. In this context, two case studies were selected in order to demonstrate the potential of a quality-by-design (QbD) strategy when applied to two specific phases of the method lifecycle: the pre-validation study and the validation step. The first case study focused on the improvement of a liquid chromatography (LC) coupled to mass spectrometry (MS) stability-indicating method by the means of the QbD concept. The design of experiments (DoE) conducted during the optimization step (i.e. determination of the qualitative design space (DS)) was performed a posteriori. Additional experiments were performed in order to simultaneously conduct the pre-validation study to assist in defining the DoE to be conducted during the formal validation step. This predicted protocol was compared to the one used during the formal validation. A second case study based on the LC/MS-MS determination of glucosamine and galactosamine in human plasma was considered in order to illustrate an innovative strategy allowing the QbD methodology to be incorporated during the validation phase. An operational space, defined by the qualitative DS, was considered during the validation process rather than a specific set of working conditions as conventionally performed. Results of all the validation parameters conventionally studied were compared to those obtained with this innovative approach for glucosamine and galactosamine. Using this strategy, qualitative and quantitative information were obtained. Consequently, an analyst using this approach would be able to select with great confidence several working conditions within the operational space rather than a given condition for the routine use of the method. This innovative strategy combines both a learning process and a thorough assessment of the risk involved.
Analytical strategies for studying stem cell metabolism
Arnold, James M.; Choi, William T.; Sreekumar, Arun
2015-01-01
Owing to their capacity for self-renewal and pluripotency, stem cells possess untold potential for revolutionizing the field of regenerative medicine through the development of novel therapeutic strategies for treating cancer, diabetes, cardiovascular and neurodegenerative diseases. Central to developing these strategies is improving our understanding of biological mechanisms responsible for governing stem cell fate and self-renewal. Increasing attention is being given to the significance of metabolism, through the production of energy and generation of small molecules, as a critical regulator of stem cell functioning. Rapid advances in the field of metabolomics now allow for in-depth profiling of stem cells both in vitro and in vivo, providing a systems perspective on key metabolic and molecular pathways which influence stem cell biology. Understanding the analytical platforms and techniques that are currently used to study stem cell metabolomics, as well as how new insights can be derived from this knowledge, will accelerate new research in the field and improve future efforts to expand our understanding of the interplay between metabolism and stem cell biology. PMID:26213533
NASA Astrophysics Data System (ADS)
Kratzer, Jan; Dědina, Jiří
2008-08-01
The compact trap-and-atomizer device was employed to trap stibine and bismuthine, and subsequently to volatilize collected analyte and atomize it for atomic absorption spectrometric detection. The device is actually the multiple microflame quartz tube atomizer (multiatomizer) with inlet arm modified to serve as the trap and to accommodate the oxygen delivery capillary employed for burning out hydrogen during the trapping step. The optimization of Sb and Bi collection in the device is presented based on a study of the influence of relevant experimental parameters on preconcentration efficiency of both analytes. The parameters studied were: (1) trap temperature during trapping and (2) hydrogen flow rate and (3) trap temperature during volatilization and (4) the stability of the trapped analyte species. Under optimized conditions, the preconcentration efficiency was 100% for both analytes. The trap-and-atomizer device can be replaced by the simple conventional externally heated quartz tube atomizer without any trap as demonstrated on the ultratrace antimony determination in groundwater reference material and mineral water samples. The interference of other hydride forming elements on Bi in-situ collection in the conventional externally heated quartz tube atomizer was investigated.
Dynamic optimization case studies in DYNOPT tool
NASA Astrophysics Data System (ADS)
Ozana, Stepan; Pies, Martin; Docekal, Tomas
2016-06-01
Dynamic programming is typically applied to optimization problems. As the analytical solutions are generally very difficult, chosen software tools are used widely. These software packages are often third-party products bound for standard simulation software tools on the market. As typical examples of such tools, TOMLAB and DYNOPT could be effectively applied for solution of problems of dynamic programming. DYNOPT will be presented in this paper due to its licensing policy (free product under GPL) and simplicity of use. DYNOPT is a set of MATLAB functions for determination of optimal control trajectory by given description of the process, the cost to be minimized, subject to equality and inequality constraints, using orthogonal collocation on finite elements method. The actual optimal control problem is solved by complete parameterization both the control and the state profile vector. It is assumed, that the optimized dynamic model may be described by a set of ordinary differential equations (ODEs) or differential-algebraic equations (DAEs). This collection of functions extends the capability of the MATLAB Optimization Tool-box. The paper will introduce use of DYNOPT in the field of dynamic optimization problems by means of case studies regarding chosen laboratory physical educational models.
Spatiotemporal and geometric optimization of sensor arrays for detecting analytes in fluids
Lewis, Nathan S.; Freund, Michael S.; Briglin, Shawn S.; Tokumaru, Phillip; Martin, Charles R.; Mitchell, David
2009-09-29
Sensor arrays and sensor array systems for detecting analytes in fluids. Sensors configured to generate a response upon introduction of a fluid containing one or more analytes can be located on one or more surfaces relative to one or more fluid channels in an array. Fluid channels can take the form of pores or holes in a substrate material. Fluid channels can be formed between one or more substrate plates. Sensor can be fabricated with substantially optimized sensor volumes to generate a response having a substantially maximized signal to noise ratio upon introduction of a fluid containing one or more target analytes. Methods of fabricating and using such sensor arrays and systems are also disclosed.
Spatiotemporal and geometric optimization of sensor arrays for detecting analytes fluids
Lewis, Nathan S.; Freund, Michael S.; Briglin, Shawn M.; Tokumaru, Phil; Martin, Charles R.; Mitchell, David T.
2006-10-17
Sensor arrays and sensor array systems for detecting analytes in fluids. Sensors configured to generate a response upon introduction of a fluid containing one or more analytes can be located on one or more surfaces relative to one or more fluid channels in an array. Fluid channels can take the form of pores or holes in a substrate material. Fluid channels can be formed between one or more substrate plates. Sensor can be fabricated with substantially optimized sensor volumes to generate a response having a substantially maximized signal to noise ratio upon introduction of a fluid containing one or more target analytes. Methods of fabricating and using such sensor arrays and systems are also disclosed.
Converse, Sarah J.; Shelley, Kevin J.; Morey, Steve; Chan, Jeffrey; LaTier, Andrea; Scafidi, Carolyn; Crouse, Deborah T.; Runge, Michael C.
2011-01-01
The resources available to support conservation work, whether time or money, are limited. Decision makers need methods to help them identify the optimal allocation of limited resources to meet conservation goals, and decision analysis is uniquely suited to assist with the development of such methods. In recent years, a number of case studies have been described that examine optimal conservation decisions under fiscal constraints; here we develop methods to look at other types of constraints, including limited staff and regulatory deadlines. In the US, Section Seven consultation, an important component of protection under the federal Endangered Species Act, requires that federal agencies overseeing projects consult with federal biologists to avoid jeopardizing species. A benefit of consultation is negotiation of project modifications that lessen impacts on species, so staff time allocated to consultation supports conservation. However, some offices have experienced declining staff, potentially reducing the efficacy of consultation. This is true of the US Fish and Wildlife Service's Washington Fish and Wildlife Office (WFWO) and its consultation work on federally-threatened bull trout (Salvelinus confluentus). To improve effectiveness, WFWO managers needed a tool to help allocate this work to maximize conservation benefits. We used a decision-analytic approach to score projects based on the value of staff time investment, and then identified an optimal decision rule for how scored projects would be allocated across bins, where projects in different bins received different time investments. We found that, given current staff, the optimal decision rule placed 80% of informal consultations (those where expected effects are beneficial, insignificant, or discountable) in a short bin where they would be completed without negotiating changes. The remaining 20% would be placed in a long bin, warranting an investment of seven days, including time for negotiation. For formal
Ho, Chao Chung
2011-07-15
Ever since Taiwan's National Health Insurance implemented the diagnosis-related groups payment system in January 2010, hospital income has declined. Therefore, to meet their medical waste disposal needs, hospitals seek suppliers that provide high-quality services at a low cost. The enactment of the Waste Disposal Act in 1974 had facilitated some improvement in the management of waste disposal. However, since the implementation of the National Health Insurance program, the amount of medical waste from disposable medical products has been increasing. Further, of all the hazardous waste types, the amount of infectious medical waste has increased at the fastest rate. This is because of the increase in the number of items considered as infectious waste by the Environmental Protection Administration. The present study used two important findings from previous studies to determine the critical evaluation criteria for selecting infectious medical waste disposal firms. It employed the fuzzy analytic hierarchy process to set the objective weights of the evaluation criteria and select the optimal infectious medical waste disposal firm through calculation and sorting. The aim was to propose a method of evaluation with which medical and health care institutions could objectively and systematically choose appropriate infectious medical waste disposal firms.
Ho, Chao Chung
2011-07-01
Ever since Taiwan's National Health Insurance implemented the diagnosis-related groups payment system in January 2010, hospital income has declined. Therefore, to meet their medical waste disposal needs, hospitals seek suppliers that provide high-quality services at a low cost. The enactment of the Waste Disposal Act in 1974 had facilitated some improvement in the management of waste disposal. However, since the implementation of the National Health Insurance program, the amount of medical waste from disposable medical products has been increasing. Further, of all the hazardous waste types, the amount of infectious medical waste has increased at the fastest rate. This is because of the increase in the number of items considered as infectious waste by the Environmental Protection Administration. The present study used two important findings from previous studies to determine the critical evaluation criteria for selecting infectious medical waste disposal firms. It employed the fuzzy analytic hierarchy process to set the objective weights of the evaluation criteria and select the optimal infectious medical waste disposal firm through calculation and sorting. The aim was to propose a method of evaluation with which medical and health care institutions could objectively and systematically choose appropriate infectious medical waste disposal firms.
Many-objective optimization and visual analytics reveal key trade-offs for London's water supply
NASA Astrophysics Data System (ADS)
Matrosov, Evgenii S.; Huskova, Ivana; Kasprzyk, Joseph R.; Harou, Julien J.; Lambert, Chris; Reed, Patrick M.
2015-12-01
In this study, we link a water resource management simulator to multi-objective search to reveal the key trade-offs inherent in planning a real-world water resource system. We consider new supplies and demand management (conservation) options while seeking to elucidate the trade-offs between the best portfolios of schemes to satisfy projected water demands. Alternative system designs are evaluated using performance measures that minimize capital and operating costs and energy use while maximizing resilience, engineering and environmental metrics, subject to supply reliability constraints. Our analysis shows many-objective evolutionary optimization coupled with state-of-the art visual analytics can help planners discover more diverse water supply system designs and better understand their inherent trade-offs. The approach is used to explore future water supply options for the Thames water resource system (including London's water supply). New supply options include a new reservoir, water transfers, artificial recharge, wastewater reuse and brackish groundwater desalination. Demand management options include leakage reduction, compulsory metering and seasonal tariffs. The Thames system's Pareto approximate portfolios cluster into distinct groups of water supply options; for example implementing a pipe refurbishment program leads to higher capital costs but greater reliability. This study highlights that traditional least-cost reliability constrained design of water supply systems masks asset combinations whose benefits only become apparent when more planning objectives are considered.
CENTRAL PLATEAU REMEDIATION OPTIMIZATION STUDY
BERGMAN, T. B.; STEFANSKI, L. D.; SEELEY, P. N.; ZINSLI, L. C.; CUSACK, L. J.
2012-09-19
THE CENTRAL PLATEAU REMEDIATION OPTIMIZATION STUDY WAS CONDUCTED TO DEVELOP AN OPTIMAL SEQUENCE OF REMEDIATION ACTIVITIES IMPLEMENTING THE CERCLA DECISION ON THE CENTRAL PLATEAU. THE STUDY DEFINES A SEQUENCE OF ACTIVITIES THAT RESULT IN AN EFFECTIVE USE OF RESOURCES FROM A STRATEGIC PERSPECTIVE WHEN CONSIDERING EQUIPMENT PROCUREMENT AND STAGING, WORKFORCE MOBILIZATION/DEMOBILIZATION, WORKFORCE LEVELING, WORKFORCE SKILL-MIX, AND OTHER REMEDIATION/DISPOSITION PROJECT EXECUTION PARAMETERS.
Analytical optimization of demand management strategies across all urban water use sectors
NASA Astrophysics Data System (ADS)
Friedman, Kenneth; Heaney, James P.; Morales, Miguel; Palenchar, John
2014-07-01
An effective urban water demand management program can greatly influence both peak and average demand and therefore long-term water supply and infrastructure planning. Although a theoretical framework for evaluating residential indoor demand management has been well established, little has been done to evaluate other water use sectors such as residential irrigation in a compatible manner for integrating these results into an overall solution. This paper presents a systematic procedure to evaluate the optimal blend of single family residential irrigation demand management strategies to achieve a specified goal based on performance functions derived from parcel level tax assessor's data linked to customer level monthly water billing data. This framework is then generalized to apply to any urban water sector, as exponential functions can be fit to all resulting cumulative water savings functions. Two alternative formulations are presented: maximize net benefits, or minimize total costs subject to satisfying a target water savings. Explicit analytical solutions are presented for both formulations based on appropriate exponential best fits of performance functions. A direct result of this solution is the dual variable which represents the marginal cost of water saved at a specified target water savings goal. A case study of 16,303 single family irrigators in Gainesville Regional Utilities utilizing high quality tax assessor and monthly billing data along with parcel level GIS data provide an illustrative example of these techniques. Spatial clustering of targeted homes can be easily performed in GIS to identify priority demand management areas.
Three-dimensional magnetic optimization of accelerator magnets using an analytic strip model
Rochepault, Etienne Aubert, Guy; Vedrine, Pierre
2014-07-14
The end design is a critical step in the design of superconducting accelerator magnets. First, the strain energy of the conductors must be minimized, which can be achieved using differential geometry. The end design also requires an optimization of the magnetic field homogeneity. A mechanical and magnetic model for the conductors, using developable strips, is described in this paper. This model can be applied to superconducting Rutherford cables, and it is particularly suitable for High Temperature Superconducting tapes. The great advantage of this approach is analytic simplifications in the field computation, allowing for very fast and accurate computations, which save a considerable computational time during the optimization process. Some 3D designs for dipoles are finally proposed, and it is shown that the harmonic integrals can be easily optimized using this model.
Analytical study of magnetohydrodynamic propulsion stability
NASA Astrophysics Data System (ADS)
Abdollahzadeh Jamalabadi, M. Y.
2014-09-01
In this paper an analytical solution for the stability of the fully developed flow drive in a magneto-hydro-dynamic pump with pulsating transverse Eletro-magnetic fields is presented. To do this, a theoretical model of the flow is developed and the analytical results are obtained for both the cylindrical and Cartesian configurations that are proper to use in the propulsion of marine vessels. The governing parabolic momentum PDEs are transformed into an ordinary differential equation using approximate velocity distribution. The numerical results are obtained and asymptotic analyses are built to discover the mathematical behavior of the solutions. The maximum velocity in a magneto-hydro-dynamic pump versus time for various values of the Stuart number, electro-magnetic interaction number, Reynolds number, aspect ratio, as well as the magnetic and electrical angular frequency and the shift of the phase angle is presented. Results show that for a high Stuart number there is a frequency limit for stability of the fluid flow in a certain direction of the flow. This stability frequency is dependent on the geometric parameters of a channel.
Visual Analytics Methodology for Eye Movement Studies.
Andrienko, G; Andrienko, N; Burch, M; Weiskopf, D
2012-12-01
Eye movement analysis is gaining popularity as a tool for evaluation of visual displays and interfaces. However, the existing methods and tools for analyzing eye movements and scanpaths are limited in terms of the tasks they can support and effectiveness for large data and data with high variation. We have performed an extensive empirical evaluation of a broad range of visual analytics methods used in analysis of geographic movement data. The methods have been tested for the applicability to eye tracking data and the capability to extract useful knowledge about users' viewing behaviors. This allowed us to select the suitable methods and match them to possible analysis tasks they can support. The paper describes how the methods work in application to eye tracking data and provides guidelines for method selection depending on the analysis tasks.
Analytical study of twin-jet shielding
NASA Technical Reports Server (NTRS)
Gerhold, C. H.
1980-01-01
The development of an analytical model, an aircraft noise prediction computer program, to estimate the shielding of one jet by an adjacent jet in a twin jet configuration, is discussed. Noise estimations included consideration not only of noise sources on the aircraft, but also of the propagation path between source and receiver. A three-dimensional case is considered in which noise source is a discrete frequency point source at rest with respect to the jet axis. The shielding jet is assumed to be a cylinder of heated flow in which the temperature and flow velocity profiles are constant across the jet. The effect on shielding of the orientation of the emitting jet with respect to the shielding jet was investigated. Forward and backward scattering phenomena as well as the influence of jet flow speed were also investigated.
NASA Astrophysics Data System (ADS)
Yan, Su; Ghasemi-Nejhad, Mehrdad N.
2007-12-01
In this paper, models of adaptive composite panels with surface-mounted/embedded piezoelectric patches are analytically built using the Lagrange-Rayleigh-Ritz method (LRRM), verified through experiments and finite element method (FEM), and used in piezoelectric actuator placement optimization and vibration control. Two panels are considered: a cantilevered adaptive composite beam (ACB) and an adaptive circular composite plate (ACCP) with complex boundaries. The inertia and stiffness of the surface-mounted/embedded piezoelectric patches are included in the developed models. To obtain the mode shapes of the ACCP, which are essential to the LRRM modeling, the method of separation of variables is employed and Bessel series and modified Bessel series are introduced. The built models are verified by experiments for the ACB and by the FEM for the ACCP. The actuation configurations of the piezoelectric patches in the panels are optimized based on the introduced analytical model. Finally, with the optimal locations of the piezoelectric patches, the vibration suppression of the ACB and the ACCP is experimentally and numerically carried out, and excellent vibration suppressions for both adaptive panels are obtained.
Structural optimization for the avoidance of self-excited vibrations based on analytical models
NASA Astrophysics Data System (ADS)
Spelsberg-Korspeter, Gottfried
2010-11-01
Self-excited vibrations are a severe problem in many technical applications. In many cases they are caused by friction as for example in disk and drum brakes, clutches, saws and paper calenders. The goal to suppress self-excited vibrations can be reached by active and passive techniques, the latter ones being preferable due to the lower costs. Among design engineers it is known that breaking the symmetries of structures is sometimes helpful to avoid self-excited vibrations. This has been verified from an analytical point of view in a recent paper. The goal of the present paper is to use this analytical insight for a systematic structural optimization of rotors in frictional contact. The first system investigated is a simple discrete model of a rotor in frictional contact. As a continuous example a rotating beam in frictional contact is considered and optimized with respect to its bending stiffness. Finally a brake disk is optimized giving some attention to the feasibility of the modifications for the production process.
Sanderson, Ruth M; Catton, Philip P
2011-05-01
This paper presents an analytical modeling technique for the simulation of long-range ultrasonic guided waves in structures. The model may be used to predict the displacement field in a prismatic structure arising from any excitation arrangement and may therefore be used as a tool to design new inspection systems. It is computationally efficient and relatively simple to implement, yet gives accuracy similar to finite element analysis and semi-analytical finite element analysis methods. The model has many potential applications; one example is the optimization of part-circumferential arrays where access to the full circumference of the pipe is restricted. The model has been successfully validated by comparison with finite element solutions. Experimental validation has also been carried out using an array of piezoelectric transducer elements to measure the displacement field arising from a single transducer element in an 88.9-mm-diameter pipe. Good agreement has been obtained between the two models and the experimental data.
NASA Astrophysics Data System (ADS)
Frunză, T.; Susan-Resiga, R.; Muntean, S.; Bernad, S.
2010-08-01
The paper presents the authors ongoing efforts to develop a robust and efficient numerical methodology, and the associated expert software, for analysis, design and optimization of hydrofoil cascades. We developed, so far, a Finite Element solver with streamfunction formulation for incompressible, inviscid and irrotational cascade flow, using a modern software infrastructure, and efficient implementation. Two test cases will be presented to evaluate the accuracy of our CASCADExpert code. In the first case, our code is tested for a thin hydrofoil cascade designed with the quasi-analytical approach. Second, the blade loading and thickness distributions obtain with our code from a given hydrofoil shape are used in an inverse design method. As a result, an optimized hydrofoil cascade is obtained. The pressure distribution on the original and optimized hydrofoil cascades is compared. We have applied the method in order to optimize the turbine and pump hydrofoil cascades, respectively. Consequently, a new method is developed in order to generate the optimized hydrofoil cascade geometry for hydraulic machinery.
Ke, Quan; Luo, Weijie; Yan, Guozheng; Yang, Kai
2016-04-01
A wireless power transfer system based on the weakly inductive coupling makes it possible to provide the endoscope microrobot (EMR) with infinite power. To facilitate the patients' inspection with the EMR system, the diameter of the transmitting coil is enlarged to 69 cm. Due to the large transmitting range, a high quality factor of the Litz-wire transmitting coil is a necessity to ensure the intensity of magnetic field generated efficiently. Thus, this paper builds an analytical model of the transmitting coil, and then, optimizes the parameters of the coil by enlarging the quality factor. The lumped model of the transmitting coil includes three parameters: ac resistance, self-inductance, and stray capacitance. Based on the exact two-dimension solution, the accurate analytical expression of ac resistance is derived. Several transmitting coils of different specifications are utilized to verify this analytical expression, being in good agreements with the measured results except the coils with a large number of strands. Then, the quality factor of transmitting coils can be well predicted with the available analytical expressions of self- inductance and stray capacitance. Owing to the exact estimation of quality factor, the appropriate coil turns of the transmitting coil is set to 18-40 within the restrictions of transmitting circuit and human tissue issues. To supply enough energy for the next generation of the EMR equipped with a Ø9.5×10.1 mm receiving coil, the coil turns of the transmitting coil is optimally set to 28, which can transfer a maximum power of 750 mW with the remarkable delivering efficiency of 3.55%. PMID:26292335
Holistic versus Analytic Evaluation of EFL Writing: A Case Study
ERIC Educational Resources Information Center
Ghalib, Thikra K.; Al-Hattami, Abdulghani A.
2015-01-01
This paper investigates the performance of holistic and analytic scoring rubrics in the context of EFL writing. Specifically, the paper compares EFL students' scores on a writing task using holistic and analytic scoring rubrics. The data for the study was collected from 30 participants attending an English undergraduate program in a Yemeni…
Rosado-Méndez, I; Palma, B A; Brandan, M E
2008-12-01
Contrast-medium-enhanced digital mammography (CEDM) is an image subtraction technique which might help unmasking lesions embedded in very dense breasts. Previous works have stated the feasibility of CEDM and the imperative need of radiological optimization. This work presents an extension of a former analytical formalism to predict contrast-to-noise ratio (CNR) in subtracted mammograms. The goal is to optimize radiological parameters available in a clinical mammographic unit (x-ray tube anode/filter combination, voltage, and loading) by maximizing CNR and minimizing total mean glandular dose (D(gT)), simulating the experimental application of an iodine-based contrast medium and the image subtraction under dual-energy nontemporal, and single- or dual-energy temporal modalities. Total breast-entrance air kerma is limited to a fixed 8.76 mGy (1 R, similar to screening studies). Mathematical expressions obtained from the formalism are evaluated using computed mammographic x-ray spectra attenuated by an adipose/glandular breast containing an elongated structure filled with an iodinated solution in various concentrations. A systematic study of contrast, its associated variance, and CNR for different spectral combinations is performed, concluding in the proposal of optimum x-ray spectra. The linearity between contrast in subtracted images and iodine mass thickness is proven, including the determination of iodine visualization limits based on Rose's detection criterion. Finally, total breast-entrance air kerma is distributed between both images in various proportions in order to maximize the figure of merit CNR2/D(gT). Predicted results indicate the advantage of temporal subtraction (either single- or dual-energy modalities) with optimum parameters corresponding to high-voltage, strongly hardened Rh/Rh spectra. For temporal techniques, CNR was found to depend mostly on the energy of the iodinated image, and thus reduction in D(gT) could be achieved if the spectral energy
Verifiable Adaptive Control with Analytical Stability Margins by Optimal Control Modification
NASA Technical Reports Server (NTRS)
Nguyen, Nhan T.
2010-01-01
This paper presents a verifiable model-reference adaptive control method based on an optimal control formulation for linear uncertain systems. A predictor model is formulated to enable a parameter estimation of the system parametric uncertainty. The adaptation is based on both the tracking error and predictor error. Using a singular perturbation argument, it can be shown that the closed-loop system tends to a linear time invariant model asymptotically under an assumption of fast adaptation. A stability margin analysis is given to estimate a lower bound of the time delay margin using a matrix measure method. Using this analytical method, the free design parameter n of the optimal control modification adaptive law can be determined to meet a specification of stability margin for verification purposes.
NASA Astrophysics Data System (ADS)
Akhtar, Taimoor; Shoemaker, Christine
2016-04-01
Watershed model calibration is inherently a multi-criteria problem. Conflicting trade-offs exist between different quantifiable calibration criterions indicating the non-existence of a single optimal parameterization. Hence, many experts prefer a manual approach to calibration where the inherent multi-objective nature of the calibration problem is addressed through an interactive, subjective, time-intensive and complex decision making process. Multi-objective optimization can be used to efficiently identify multiple plausible calibration alternatives and assist calibration experts during the parameter estimation process. However, there are key challenges to the use of multi objective optimization in the parameter estimation process which include: 1) multi-objective optimization usually requires many model simulations, which is difficult for complex simulation models that are computationally expensive; and 2) selection of one from numerous calibration alternatives provided by multi-objective optimization is non-trivial. This study proposes a "Hybrid Automatic Manual Strategy" (HAMS) for watershed model calibration to specifically address the above-mentioned challenges. HAMS employs a 3-stage framework for parameter estimation. Stage 1 incorporates the use of an efficient surrogate multi-objective algorithm, GOMORS, for identification of numerous calibration alternatives within a limited simulation evaluation budget. The novelty of HAMS is embedded in Stages 2 and 3 where an interactive visual and metric based analytics framework is available as a decision support tool to choose a single calibration from the numerous alternatives identified in Stage 1. Stage 2 of HAMS provides a goodness-of-fit measure / metric based interactive framework for identification of a small subset (typically less than 10) of meaningful and diverse set of calibration alternatives from the numerous alternatives obtained in Stage 1. Stage 3 incorporates the use of an interactive visual
NASA Astrophysics Data System (ADS)
Guerrero, R. D.; Arango, C. A.; Reyes, A.
2016-07-01
We recently proposed a Quantum Optimal Control (QOC) method constrained to build pulses from analytical pulse shapes [R. D. Guerrero et al., J. Chem. Phys. 143(12), 124108 (2015)]. This approach was applied to control the dissociation channel yields of the diatomic molecule KH, considering three potential energy curves and one degree of freedom. In this work, we utilized this methodology to study the strong field control of the cis-trans photoisomerization of 11-cis retinal. This more complex system was modeled with a Hamiltonian comprising two potential energy surfaces and two degrees of freedom. The resulting optimal pulse, made of 6 linearly chirped pulses, was capable of controlling the population of the trans isomer on the ground electronic surface for nearly 200 fs. The simplicity of the pulse generated with our QOC approach offers two clear advantages: a direct analysis of the sequence of events occurring during the driven dynamics, and its reproducibility in the laboratory with current laser technologies.
Design optimization of thin-film/wafer-based tandem junction solar cells using analytical modeling
NASA Astrophysics Data System (ADS)
Davidson, Lauren; Toor, Fatima
2016-03-01
Several research groups are developing solar cells of varying designs and materials that are high efficiency as well as cost competitive with the single junction silicon (Si) solar cells commercially produced today. One of these solar cell designs is a tandem junction solar cell comprised of perovskite (CH3NH3PbI3) and silicon (Si). Loper et al.1 was able to create a 13.4% efficient tandem cell using a perovskite top cell and a Si bottom cell, and researchers are confident that the perovskite/Si tandem cell can be optimized in order to reach higher efficiencies without introducing expensive manufacturing processes. However, there are currently no commercially available software capable of modeling a tandem cell that is based on a thin-film based bottom cell and a wafer-based top cell. While PC1D2 and SCAPS3 are able to model tandem cells comprised solely of thin-film absorbers or solely of wafer-based absorbers, they result in convergence errors if a thin-film/wafer-based tandem cell, such as the perovskite/ Si cell, is modeled. The Matlab-based analytical model presented in this work is capable of modeling a thin-film/wafer-based tandem solar cell. The model allows a user to adjust the top and bottom cell parameters, such as reflectivity, material bandgaps, donor and acceptor densities, and material thicknesses, in order to optimize the short circuit current, open circuit voltage, and quantum efficiency of the tandem solar cell. Using the Matlab-based analytical model, we were able optimize a perovskite/Si tandem cell with an efficiency greater than 30%.
Interplanetary Program to Optimize Simulated Trajectories (IPOST). Volume 2: Analytic manual
NASA Technical Reports Server (NTRS)
Hong, P. E.; Kent, P. D.; Olson, D. W.; Vallado, C. A.
1992-01-01
The Interplanetary Program to Optimize Space Trajectories (IPOST) is intended to support many analysis phases, from early interplanetary feasibility studies through spacecraft development and operations. The IPOST output provides information for sizing and understanding mission impacts related to propulsion, guidance, communications, sensor/actuators, payload, and other dynamic and geometric environments. IPOST models three degree of freedom trajectory events, such as launch/ascent, orbital coast, propulsive maneuvering (impulsive and finite burn), gravity assist, and atmospheric entry. Trajectory propagation is performed using a choice of Cowell, Encke, Multiconic, Onestep, or Conic methods. The user identifies a desired sequence of trajectory events, and selects which parameters are independent (controls) and dependent (targets), as well as other constraints and the cost function. Targeting and optimization is performed using the Stanford NPSOL algorithm. IPOST structure allows subproblems within a master optimization problem to aid in the general constrained parameter optimization solution. An alternate optimization method uses implicit simulation and collocation techniques.
Analytical studies: a framework for quality improvement design and analysis.
Provost, Lloyd P
2011-04-01
Conducting studies for learning is fundamental to improvement. Deming emphasised that the reason for conducting a study is to provide a basis for action on the system of interest. He classified studies into two types depending on the intended target for action. An enumerative study is one in which action will be taken on the universe that was studied. An analytical study is one in which action will be taken on a cause system to improve the future performance of the system of interest. The aim of an enumerative study is estimation, while an analytical study focuses on prediction. Because of the temporal nature of improvement, the theory and methods for analytical studies are a critical component of the science of improvement.
Comparison of optimization methods for the hyperspectral semi-analytical model
NASA Astrophysics Data System (ADS)
Du, KePing; Xi, Ying; Sun, LiRan; Zhang, Xuegang
2009-01-01
During recent years, more and more efforts have been focused on developing new models based on ocean optics theory to retrieve water's bio-geo-chemical parameters or inherent optical properties (IOPs) from either ocean color imagery or in situ measurements. Basically, these models are sophisticated, and hard to invert directly, look up table (LUT) technique or optimization methods are employed to retrieve the unknown parameters, e.g., chlorophyll concentration, CDOM absorption, etc. Many researches prefer to use time-consuming global optimization methods, e.g., genetic or evolutionary algorithm, etc. In this study, different optimization methods, smooth nonlinear optimization (NLP), global optimization (GO), nonsmooth optimization (NSP), are compared based on the sophisticated hyper-spectral semianalytical (SA) algorithm developed by Lee et al., retrieval accuracy and performance are evaluated. It is found that retrieval accuracy don't have much difference, the performance difference, however, is much larger, NLP works very well for the SA model. For a given model, it is better to analyze the model is linear, nonlinear or nonsmooth category problem, sometimes, convex also need to be determined, or linearize some nonsmooth problem caused by if decision, then select the corresponding category optimization methods. Initial values selection is a big issue for optimization, the simple statistical models (e.g., OC2 or OC4) are used to retrieve the unknowns as initial values.
Analytical optimal controls for the state constrained addition and removal of cryoprotective agents
Chicone, Carmen C.; Critser, John K.
2014-01-01
Cryobiology is a field with enormous scientific, financial and even cultural impact. Successful cryopreservation of cells and tissues depends on the equilibration of these materials with high concentrations of permeating chemicals (CPAs) such as glycerol or 1,2 propylene glycol. Because cells and tissues are exposed to highly anisosmotic conditions, the resulting gradients cause large volume fluctuations that have been shown to damage cells and tissues. On the other hand, there is evidence that toxicity to these high levels of chemicals is time dependent, and therefore it is ideal to minimize exposure time as well. Because solute and solvent flux is governed by a system of ordinary differential equations, CPA addition and removal from cells is an ideal context for the application of optimal control theory. Recently, we presented a mathematical synthesis of the optimal controls for the ODE system commonly used in cryobiology in the absence of state constraints and showed that controls defined by this synthesis were optimal. Here we define the appropriate model, analytically extend the previous theory to one encompassing state constraints, and as an example apply this to the critical and clinically important cell type of human oocytes, where current methodologies are either difficult to implement or have very limited success rates. We show that an enormous increase in equilibration efficiency can be achieved under the new protocols when compared to classic protocols, potentially allowing a greatly increased survival rate for human oocytes, and pointing to a direction for the cryopreservation of many other cell types. PMID:22527943
Semi Active Control of Civil Structures, Analytical and Numerical Studies
NASA Astrophysics Data System (ADS)
Kerboua, M.; Benguediab, M.; Megnounif, A.; Benrahou, K. H.; Kaoulala, F.
numerical example of the parallel R-L piezoelectric vibration shunt control simulated with MATLAB® is presented. An analytical study of the resistor-inductor (R-L) passive piezoelectric vibration shunt control of a cantilever beam was undertaken. The modal and strain analyses were performed by varying the material properties and geometric configurations of the piezoelectric transducer in relation to the structure in order to maximize the mechanical strain produced in the piezoelectric transducer.
Studying Human Dynamics Through Web Analytics
NASA Astrophysics Data System (ADS)
Ramasco, Jose; Goncalves, Bruno
2008-03-01
When Tim Berners Lee, a physicist at the European Center for Nuclear Research (CERN) first conceived the World Wide Web (WWW) in 1990 as a way to facilitate the sharing of scientific information and results among the centers different researchers and groups, even the most ingenious of science fiction writers could not have imagined the role it would come to play in the following decades. The increasing ubiquitousness of Internet access and the frequency with which people interact with it raise the possibility of using it to better observe, understand, and even monitor several aspects of human social behavior. Websites with large numbers of frequently returning users, such as search engines, company or university websites, are ideal for this task. The properly anonymized logs detailing the access history to Emory University's website is studied. We find that a small number of users is responsible for a finite fraction of the total activity. A saturation phenomenon is observed where, certain connections age, becoming less attractive to new activity over time. Finally, by measuring the average activity as a function of the day of the week, we find that productivity seems to be higher on Tuesdays and Wednesdays, with Sundays being the least active day.
Analytical and phenomenological studies of rotating turbulence
NASA Technical Reports Server (NTRS)
Mahalov, Alex; Zhou, YE
1995-01-01
A framework, which combines mathematical analysis, closure theory, and phenomenological treatment, is developed to study the spectral transfer process and reduction of dimensionality in turbulent flows that are subject to rotation. First, we outline a mathematical procedure that is particularly appropriate for problems with two disparate time scales. The approach which is based on the Green's method leads to the Poincare velocity variables and the Poincare transformation when applied to rotating turbulence. The effects of the rotation are now reflected in the modifications to the convolution of a nonlinear term. The Poincare transformed equations are used to obtain a time-dependent analog of the Taylor-Proudman theorem valid in the asymptotic limit when the non-dimensional parameter mu is identical to Omega(t) approaches infinity (Omega is the rotation rate and t is the time). The 'split' of the energy transfer in both direct and inverse directions is established. Secondly, we apply the Eddy-Damped-Quasinormal-Markovian (EDQNM) closure to the Poincare transformed Euler/Navier-Stokes equations. This closure leads to expressions for the spectral energy transfer. In particular, an unique triple velocity decorrelation time is derived with an explicit dependence on the rotation rate. This provides an important input for applying the phenomenological treatment of Zhou. In order to characterize the relative strength of rotation, another non-dimensional number, a spectral Rossby number, which is defined as the ratio of rotation and turbulence time scales, is introduced. Finally, the energy spectrum and the spectral eddy viscosity are deduced.
Cardiff, Michael; Liu, Xiaoyi; Kitanidis, Peter K; Parker, Jack; Kim, Ungtae
2010-04-01
Dense non-aqueous phase liquid (DNAPL) spills represent a potential long-term source of aquifer contamination, and successful low-cost remediation may require a combination of both plume management and source treatment. In addition, substantial uncertainty exists in many of the parameters that control field-scale behavior of DNAPL sources and plumes. For these reasons, cost optimization of DNAPL cleanup needs to consider multiple treatment options and their associated costs while also gauging the influence of prediction uncertainty on expected costs. In this paper, we present a management methodology for field-scale DNAPL source and plume management under uncertainty. Using probabilistic methods, historical data and prior information are combined to produce a set of equally likely realizations of true field conditions (i.e., parameter sets). These parameter sets are then used in a simulation-optimization framework to produce DNAPL cleanup solutions that have the lowest possible expected net present value (ENPV) cost and that are suitably cautious in the presence of high uncertainty. For simulation, we utilize a fast-running semi-analytic field-scale model of DNAPL source and plume evolution that also approximates the effects of remedial actions. The degree of model prediction uncertainty is gauged using a restricted maximum likelihood method, which helps to produce suitably cautious remediation strategies. We test our methodology on a synthetic field-scale problem with multiple source architectures, for which source zone thermal treatment and electron donor injection are considered as remedial actions. The lowest cost solution found utilizes a combination of source and plume remediation methods, and is able to successfully meet remediation constraints for a majority of possible scenarios. Comparisons with deterministic optimization results show that not taking into account uncertainty can result in optimization strategies that are not aggressive enough and result
Analytical Prediction and Optimization of Far-Field Pyroshock Test Procedures
NASA Astrophysics Data System (ADS)
Lacher, Alexander; Jungel, Nikolas; von Wagner, Utz; Bager, Annette
2012-07-01
The simulation of far-field pyroshocks is mainly performed by the use of mechanical or mechatronic devices such as hammer pendulums, shakers and piezoactors. Latter show limitations concerning frequency and acceleration ranges which does not hold for hammer pendulums or bolt guns. Their controllability, however, is rather unsatisfactory and there still exists a general lack of computational prediction tools for usually time consuming and costly far-field pyroshock tests. Mechanical minimal models of existing hammer test devices are presented and investigated by the use of the finite element and analytical methods. The tedious mechanical impact problem is reduced by introducing a nonlinear compressive spring connecting striking partners. Computational test results are verified by experiments and optimized by an evolution strategy allowing for determination of optimum test parameters. The algorithms developed are the basis for fast and efficient predictions of pyroshock tests.
Analytic Shielding Optimization to Reduce Crew Exposure to Ionizing Radiation Inside Space Vehicles
NASA Technical Reports Server (NTRS)
Gaza, Razvan; Cooper, Tim P.; Hanzo, Arthur; Hussein, Hesham; Jarvis, Kandy S.; Kimble, Ryan; Lee, Kerry T.; Patel, Chirag; Reddell, Brandon D.; Stoffle, Nicholas; Zapp, E. Neal; Shelfer, Tad D.
2009-01-01
A sustainable lunar architecture provides capabilities for leveraging out-of-service components for alternate uses. Discarded architecture elements may be used to provide ionizing radiation shielding to the crew habitat in case of a Solar Particle Event. The specific location relative to the vehicle where the additional shielding mass is placed, as corroborated with particularities of the vehicle design, has a large influence on protection gain. This effect is caused by the exponential- like decrease of radiation exposure with shielding mass thickness, which in turn determines that the most benefit from a given amount of shielding mass is obtained by placing it so that it preferentially augments protection in under-shielded areas of the vehicle exposed to the radiation environment. A novel analytic technique to derive an optimal shielding configuration was developed by Lockheed Martin during Design Analysis Cycle 3 (DAC-3) of the Orion Crew Exploration Vehicle (CEV). [1] Based on a detailed Computer Aided Design (CAD) model of the vehicle including a specific crew positioning scenario, a set of under-shielded vehicle regions can be identified as candidates for placement of additional shielding. Analytic tools are available to allow capturing an idealized supplemental shielding distribution in the CAD environment, which in turn is used as a reference for deriving a realistic shielding configuration from available vehicle components. While the analysis referenced in this communication applies particularly to the Orion vehicle, the general method can be applied to a large range of space exploration vehicles, including but not limited to lunar and Mars architecture components. In addition, the method can be immediately applied for optimization of radiation shielding provided to sensitive electronic components.
NASA Astrophysics Data System (ADS)
Teoh, Lay Eng; Khoo, Hooi Ling
2013-09-01
This study deals with two major aspects of airlines, i.e. supply and demand management. The aspect of supply focuses on the mathematical formulation of an optimal fleet management model to maximize operational profit of the airlines while the aspect of demand focuses on the incorporation of mode choice modeling as parts of the developed model. The proposed methodology is outlined in two-stage, i.e. Fuzzy Analytic Hierarchy Process is first adopted to capture mode choice modeling in order to quantify the probability of probable phenomena (for aircraft acquisition/leasing decision). Then, an optimization model is developed as a probabilistic dynamic programming model to determine the optimal number and types of aircraft to be acquired and/or leased in order to meet stochastic demand during the planning horizon. The findings of an illustrative case study show that the proposed methodology is viable. The results demonstrate that the incorporation of mode choice modeling could affect the operational profit and fleet management decision of the airlines at varying degrees.
Aeroelastic Optimization Study Based on the X-56A Model
NASA Technical Reports Server (NTRS)
Li, Wesley W.; Pak, Chan-Gi
2014-01-01
One way to increase the aircraft fuel efficiency is to reduce structural weight while maintaining adequate structural airworthiness, both statically and aeroelastically. A design process which incorporates the object-oriented multidisciplinary design, analysis, and optimization (MDAO) tool and the aeroelastic effects of high fidelity finite element models to characterize the design space was successfully developed and established. This paper presents two multidisciplinary design optimization studies using an object-oriented MDAO tool developed at NASA Armstrong Flight Research Center. The first study demonstrates the use of aeroelastic tailoring concepts to minimize the structural weight while meeting the design requirements including strength, buckling, and flutter. Such an approach exploits the anisotropic capabilities of the fiber composite materials chosen for this analytical exercise with ply stacking sequence. A hybrid and discretization optimization approach improves accuracy and computational efficiency of a global optimization algorithm. The second study presents a flutter mass balancing optimization study for the fabricated flexible wing of the X-56A model since a desired flutter speed band is required for the active flutter suppression demonstration during flight testing. The results of the second study provide guidance to modify the wing design and move the design flutter speeds back into the flight envelope so that the original objective of X-56A flight test can be accomplished successfully. The second case also demonstrates that the object-oriented MDAO tool can handle multiple analytical configurations in a single optimization run.
Behavior Analytic Contributions to the Study of Creativity
ERIC Educational Resources Information Center
Kubina, Richard M., Jr.; Morrison, Rebecca S.; Lee, David L.
2006-01-01
As researchers continue to study creativity, a behavior analytic perspective may provide new vistas by offering an additional perspective. Contemporary behavior analysis began with B. F. Skinner and offers a selectionist approach to the scientific investigation of creativity. Behavior analysis contributes to the study of creativity by…
Study of an analytical method for hexavalent chromium.
Bhargava, O P; Bumsted, H E; Grunder, F I; Hunt, B L; Manning, G E; Riemann, R A; Samuels, J K; Tatone, V; Waldschmidt, S J; Hernandez, P
1983-06-01
The diphenylcarbazide colorimetric method was evaluated by analyzing spiked PVC filters prepared by an AIHA-accredited consultant laboratory for chromium (VI). All seven participating laboratories received the samples and performed the analyses at the same time. Three laboratories simultaneously tested three alternative analytical procedures. Reduced amounts of chromium (VI) were found by both the consultant and participating laboratories when using the test procedure and one of the alternative methods. Two of the alternative analytical methods, both of which involve an alkaline extraction procedure, provided higher recoveries and more precise values for the test filters. It appears that the alkaline extraction procedure may be more appropriate for occupational health samples taken in steel industry environments which may include several interferents. Suggestions are made for further studies to determine the most appropriate analytical method.
Dimensions of Early Speech Sound Disorders: A Factor Analytic Study
ERIC Educational Resources Information Center
Lewis, Barbara A.; Freebairn, Lisa A.; Hansen, Amy J.; Stein, Catherine M.; Shriberg, Lawrence D.; Iyengar, Sudha K.; Taylor, H. Gerry
2006-01-01
The goal of this study was to classify children with speech sound disorders (SSD) empirically, using factor analytic techniques. Participants were 3-7-year olds enrolled in speech/language therapy (N=185). Factor analysis of an extensive battery of speech and language measures provided support for two distinct factors, representing the skill…
Algorithms for optimized maximum entropy and diagnostic tools for analytic continuation.
Bergeron, Dominic; Tremblay, A-M S
2016-08-01
Analytic continuation of numerical data obtained in imaginary time or frequency has become an essential part of many branches of quantum computational physics. It is, however, an ill-conditioned procedure and thus a hard numerical problem. The maximum-entropy approach, based on Bayesian inference, is the most widely used method to tackle that problem. Although the approach is well established and among the most reliable and efficient ones, useful developments of the method and of its implementation are still possible. In addition, while a few free software implementations are available, a well-documented, optimized, general purpose, and user-friendly software dedicated to that specific task is still lacking. Here we analyze all aspects of the implementation that are critical for accuracy and speed and present a highly optimized approach to maximum entropy. Original algorithmic and conceptual contributions include (1) numerical approximations that yield a computational complexity that is almost independent of temperature and spectrum shape (including sharp Drude peaks in broad background, for example) while ensuring quantitative accuracy of the result whenever precision of the data is sufficient, (2) a robust method of choosing the entropy weight α that follows from a simple consistency condition of the approach and the observation that information- and noise-fitting regimes can be identified clearly from the behavior of χ^{2} with respect to α, and (3) several diagnostics to assess the reliability of the result. Benchmarks with test spectral functions of different complexity and an example with an actual physical simulation are presented. Our implementation, which covers most typical cases for fermions, bosons, and response functions, is available as an open source, user-friendly software.
Algorithms for optimized maximum entropy and diagnostic tools for analytic continuation.
Bergeron, Dominic; Tremblay, A-M S
2016-08-01
Analytic continuation of numerical data obtained in imaginary time or frequency has become an essential part of many branches of quantum computational physics. It is, however, an ill-conditioned procedure and thus a hard numerical problem. The maximum-entropy approach, based on Bayesian inference, is the most widely used method to tackle that problem. Although the approach is well established and among the most reliable and efficient ones, useful developments of the method and of its implementation are still possible. In addition, while a few free software implementations are available, a well-documented, optimized, general purpose, and user-friendly software dedicated to that specific task is still lacking. Here we analyze all aspects of the implementation that are critical for accuracy and speed and present a highly optimized approach to maximum entropy. Original algorithmic and conceptual contributions include (1) numerical approximations that yield a computational complexity that is almost independent of temperature and spectrum shape (including sharp Drude peaks in broad background, for example) while ensuring quantitative accuracy of the result whenever precision of the data is sufficient, (2) a robust method of choosing the entropy weight α that follows from a simple consistency condition of the approach and the observation that information- and noise-fitting regimes can be identified clearly from the behavior of χ^{2} with respect to α, and (3) several diagnostics to assess the reliability of the result. Benchmarks with test spectral functions of different complexity and an example with an actual physical simulation are presented. Our implementation, which covers most typical cases for fermions, bosons, and response functions, is available as an open source, user-friendly software. PMID:27627408
Algorithms for optimized maximum entropy and diagnostic tools for analytic continuation
NASA Astrophysics Data System (ADS)
Bergeron, Dominic; Tremblay, A.-M. S.
2016-08-01
Analytic continuation of numerical data obtained in imaginary time or frequency has become an essential part of many branches of quantum computational physics. It is, however, an ill-conditioned procedure and thus a hard numerical problem. The maximum-entropy approach, based on Bayesian inference, is the most widely used method to tackle that problem. Although the approach is well established and among the most reliable and efficient ones, useful developments of the method and of its implementation are still possible. In addition, while a few free software implementations are available, a well-documented, optimized, general purpose, and user-friendly software dedicated to that specific task is still lacking. Here we analyze all aspects of the implementation that are critical for accuracy and speed and present a highly optimized approach to maximum entropy. Original algorithmic and conceptual contributions include (1) numerical approximations that yield a computational complexity that is almost independent of temperature and spectrum shape (including sharp Drude peaks in broad background, for example) while ensuring quantitative accuracy of the result whenever precision of the data is sufficient, (2) a robust method of choosing the entropy weight α that follows from a simple consistency condition of the approach and the observation that information- and noise-fitting regimes can be identified clearly from the behavior of χ2 with respect to α , and (3) several diagnostics to assess the reliability of the result. Benchmarks with test spectral functions of different complexity and an example with an actual physical simulation are presented. Our implementation, which covers most typical cases for fermions, bosons, and response functions, is available as an open source, user-friendly software.
Vilim, R.B.; Wegerich, S.W.
1995-12-31
A neural network originally proposed by Szu for performing pattern recognition has been modified for use in a noisy manufacturing environment. Signals from the factory floor are frequently affine transformed and, as a consequence, a signal may not be properly aligned with respect to the input node that corresponds to the signal leading edge or with respect to the number of nodes representing the time varying part. Rater than translate and scale the presented signal, an operation which because of noise can be prone to numerical error since the signal is not smoothly varying, the network in this paper has the capability to analytically translate and scale its internal representation of the signal so that it overlays the presented signal. A response surface in the neighborhood of the stored reference signal is built during, training, and covers the range of translate and scale parameter values expected. A genetic algorithm is used to search over this hilly terrain to find the optimal values of these parameters so that the reference signal overlays the presented signal. The procedure is repeated over all hypothesized pattern classes with the best fit identifying the class.
Optimal search strategies for retrieving systematic reviews from Medline: analytical survey
Montori, Victor M; Wilczynski, Nancy L; Morgan, Douglas; Haynes, R Brian
2005-01-01
Objective: To develop optimal search strategies in Medline for retrieving systematic reviews. Design: Analytical survey. Data sources: 161 journals published in 2000 indexed in Medline. Main outcome measures: The sensitivity, specificity, and precision of retrieval of systematic reviews of 4862 unique terms in 782 485 combinations of one to five terms were determined by comparison with a hand search of all articles (the criterion standard) in 161 journals published during 2000 (49 028 articles). Results: Only 753 (1.5%) of the 49 028 articles were systematic reviews. The most sensitive strategy included five terms and had a sensitivity of 99.9% (95% confidence interval 99.6% to 100%) and a specificity of 52% (51.6% to 52.5%). The strategy that best minimised the difference between sensitivity and specificity had a sensitivity of 98% (97% to 99%) and specificity of 90.8% (90.5% to 91.1%). Highest precision for multiterm strategies, 57% (54% to 60%), was achieved at a sensitivity of 71% (68% to 74%). The term “cochrane database of systematic reviews.jn.” was the most precise single term search strategy (sensitivity of 56% (52% to 60%) and precision of 96% (94% to 98%)). These strategies are available through the “limit” screen of Ovid's search interface for Medline. Conclusions: Systematic reviews can be retrieved from Medline with close to perfect sensitivity or specificity, or with high precision, by using empirical search strategies. PMID:15619601
Guerrero, R D; Arango, C A; Reyes, A
2016-07-21
We recently proposed a Quantum Optimal Control (QOC) method constrained to build pulses from analytical pulse shapes [R. D. Guerrero et al., J. Chem. Phys. 143(12), 124108 (2015)]. This approach was applied to control the dissociation channel yields of the diatomic molecule KH, considering three potential energy curves and one degree of freedom. In this work, we utilized this methodology to study the strong field control of the cis-trans photoisomerization of 11-cis retinal. This more complex system was modeled with a Hamiltonian comprising two potential energy surfaces and two degrees of freedom. The resulting optimal pulse, made of 6 linearly chirped pulses, was capable of controlling the population of the trans isomer on the ground electronic surface for nearly 200 fs. The simplicity of the pulse generated with our QOC approach offers two clear advantages: a direct analysis of the sequence of events occurring during the driven dynamics, and its reproducibility in the laboratory with current laser technologies. PMID:27448862
Assessing analytical comparability of biosimilars: GCSF as a case study.
Nupur, Neh; Singh, Sumit Kumar; Narula, Gunjan; Rathore, Anurag S
2016-10-01
The biosimilar industry is witnessing an unprecedented growth with the newer therapeutics increasing in complexity over time. A key step towards development of a biosimilar is to establish analytical comparability with the innovator product, which would otherwise affect the safety/efficacy profile of the product. Choosing appropriate analytical tools that can fulfil this objective by qualitatively and/or quantitatively assessing the critical quality attributes (CQAs) of the product is highly critical for establishing equivalence. These CQAs cover the primary and higher order structures of the product, product related variants and impurities, as well as process related impurities, and host cell related impurities. In the present work, we use such an analytical platform for assessing comparability of five approved Granulocyte Colony Stimulating Factor (GCSF) biosimilars (Emgrast, Lupifil, Colstim, Neukine and Grafeel) to the innovator product, Neupogen(®). The comparability studies involve assessing structural homogeneity, identity, secondary structure, and product related modifications. Physicochemical analytical tools include peptide mapping with mass determination, circular dichroism (CD) spectroscopy, reverse phase chromatography (RPC) and size exclusion chromatography (SEC) have been used in this exercise. Bioactivity assessment include comparison of relative potency through in vitro cell proliferation assays. The results from extensive analytical examination offer robust evidence of structural and biological similarity of the products under consideration with the pertinent innovator product. For the most part, the biosimilar drugs were found to be comparable to the innovator drug anomaly that was identified was that three of the biosimilars had a typical variant which was reported as an oxidized species in the literature. But, upon further investigation using RPC-FLD and ESI-MS we found that this is likely a conformational variant of the biotherapeutic been
Educational Optimism among Parents: A Pilot Study
ERIC Educational Resources Information Center
Räty, Hannu; Kasanen, Kati
2016-01-01
This study explored parents' (N = 351) educational optimism in terms of their trust in the possibilities of school to develop children's intelligence. It was found that educational optimism could be depicted as a bipolar factor with optimism and pessimism on the opposing ends of the same dimension. Optimistic parents indicated more satisfaction…
An analytical study on the bending of prismatic SMA beams
NASA Astrophysics Data System (ADS)
Ostadrahimi, Alireza; Arghavani, Jamal; Poorasadion, Saeid
2015-12-01
In this study, an analytical solution is presented for pure bending of shape memory alloy (SMA) beams with symmetric cross section as well as symmetric behavior in tension and compression. To this end, a three-dimensional constitutive equation is reduced to one-dimensional form and employed to study the bending response of SMA beams at high (pseudo-elasticity) and low (shape memory effect) temperatures. An analytical expression for bending stress as well as polynomial approximation for shear stress and deflection are obtained. Derived equations for bending are employed to analyze an SMA beam with rectangular cross section and results are compared with those of the finite element method. The results of this work show good agreement when compared with experimental data and finite element results. Furthermore, the existence of several zero-stress fibers during unloading of SMA beams at low temperature is demonstrated.
NASA Astrophysics Data System (ADS)
Hofman, Radek; Seibert, Petra; Kovalets, Ivan; Andronopoulos, Spyros
2015-04-01
We are concerned with source term retrieval in the case of an accident in a nuclear power with off-site consequences. The goal is to optimize atmospheric dispersion model inputs using inverse modeling of gamma dose rate measurements (instantaneous or time-integrated). These are the most abundant type of measurements provided by various radiation monitoring networks across Europe and available continuously in near-real time. Usually, a source term of an accidental release comprises of a mixture of nuclides. Unfortunately, gamma dose rate measurements do not provide a direct information on the source term composition; however, physical properties of respective nuclides (deposition properties, decay half-life) can yield some insight. In the method presented, we assume that nuclide ratios are known at least approximately, e.g. from nuclide specific observations or reactor inventory and assumptions on the accident type. The source term can be in multiple phases, each being characterized by constant nuclide ratios. The method is an extension of a well-established source term inversion approach based on the optimization of an objective function (minimization of a cost function). This function has two quadratic terms: mismatch between model and measurements weighted by an observation error covariance matrix and the deviation of the solution from a first guess weighted by the first-guess error covariance matrix. For simplicity, both error covariance matrices are approximated as diagonal. Analytical minimization of the cost function leads to a liner system of equations. Possible negative parts of the solution are iteratively removed by the means of first guess error variance reduction. Nuclide ratios enter the problem in the form of additional linear equations, where the deviations from prescribed ratios are weighted by factors; the corresponding error variance allows us to control how strongly we want to impose the prescribed ratios. This introduces some freedom into the
Dispersion of helically corrugated waveguides: Analytical, numerical, and experimental study
NASA Astrophysics Data System (ADS)
Burt, G.; Samsonov, S. V.; Ronald, K.; Denisov, G. G.; Young, A. R.; Bratman, V. L.; Phelps, A. D.; Cross, A. W.; Konoplev, I. V.; He, W.; Thomson, J.; Whyte, C. G.
2004-10-01
Helically corrugated waveguides have recently been studied for use in various applications such as interaction regions in gyrotron traveling-wave tubes and gyrotron backward-wave oscillators and as a dispersive medium for passive microwave pulse compression. The paper presents a summary of various methods that can be used for analysis of the wave dispersion of such waveguides. The results obtained from an analytical approach, simulations with the three-dimensional numerical code MAGIC, and cold microwave measurements are analyzed and compared.
Gaye, Amadou; Peakman, Tim; Tobin, Martin D; Burton, Paul R
2014-01-01
Background: Errors, introduced through poor assessment of physical measurement or because of inconsistent or inappropriate standard operating procedures for collecting, processing, storing or analysing haematological and biochemistry analytes, have a negative impact on the power of association studies using the collected data. A dataset from UK Biobank was used to evaluate the impact of pre-analytical variability on the power of association studies. Methods: First, we estimated the proportion of the variance in analyte concentration that may be attributed to delay in processing using variance component analysis. Then, we captured the proportion of heterogeneity between subjects that is due to variability in the rate of degradation of analytes, by fitting a mixed model. Finally, we evaluated the impact of delay in processing on the power of a nested case-control study using a power calculator that we developed and which takes into account uncertainty in outcome and explanatory variables measurements. Results: The results showed that (i) the majority of the analytes investigated in our analysis, were stable over a period of 36 h and (ii) some analytes were unstable and the resulting pre-analytical variation substantially decreased the power of the study, under the settings we investigated. Conclusions: It is important to specify a limited delay in processing for analytes that are very sensitive to delayed assay. If the rate of degradation of an analyte varies between individuals, any delay introduces a bias which increases with increasing delay. If pre-analytical variation occurring due to delays in sample processing is ignored, it affects adversely the power of the studies that use the data. PMID:25085103
A Web-based Geovisual Analytical System for Climate Studies
NASA Astrophysics Data System (ADS)
Sun, M.; Li, J.; Yang, C.; Schmidt, G. A.; Bambacus, M.; Cahalan, R.; Huang, Q.; Xu, C.; Noble, E.
2012-12-01
Climate studies involve petabytes of spatiotemporal datasets that are produced and archived at distributed computing resources. Scientists need an intuitive and convenient tool to explore the distributed spatiotemporal data. Geovisual analytical tools have the potential to provide such an intuitive and convenient method for scientists to access climate data, discover the relationships between various climate parameters, and communicate the results across different research communities. However, implementing a geovisual analytical tool for complex climate data in a distributed environment poses several challenges. This paper reports our efforts in developing a web-based geovisual analytical system to support the analysis of climate data generated by Intergovernmental Panel on Climate Change (IPCC), Fourth Assessment Report (AR4) models. Using the ModelE developed by NASA Goddard Institute for Space Studies (GISS) as an example, we demonstrate that the system is able to 1) manage large volume datasets over the Internet, 2) visualize 3D/4D spatiotemporal data, 3) broker various spatiotemporal statistical analyses for climate research, and 4) support interactive data analysis and knowledge discovery. This research also provides an example of how to manage, disseminate, and analyze Big Data in the 21st century.
Analytical electron microscopy study of radioactive ceramic waste form
O'Holleran, T. P.; Sinkler, W.; Moschetti, T. L.; Johnson, S. G.; Goff, K. M.
1999-11-11
A ceramic waste form has been developed to immobilize the halide high-level waste stream from electrometallurgical treatment of spent nuclear fuel. Analytical electron microscopy studies, using both scanning and transmission instruments, have been performed to characterize the microstructure of this material. The microstructure consists primarily of sodalite granules (containing the bulk of the halides) bonded together with glass. The results of these studies are discussed in detail. Insight into the waste form fabrication process developed as a result of these studies is also discussed.
Use of Analytical Solutions to Optimize Simulation of Multicomponent Three-Phase Displacements
NASA Astrophysics Data System (ADS)
Laforce, Tara
2010-05-01
The conservation law for oil/water/gas flow in porous media can be highly sensitive to numerical dispersive effects, particularly in systems with substantial partitioning of components between the gas and oil phases. As a consequence, it is not typically possible to perform field-scale simulations with a sufficiently fine-grid to accurately model compositional displacements such as CO2 injection into oil fields for storage or enhanced oil recovery (EOR). The purpose of this study is to use analytical results to demonstrate the numerical errors in water and gas injection simulations in one dimension (1D) and to discuss the applicability of simplified models in obtaining an accurate simulated solution. Recently analytical solutions have become available for simultaneous water and gas (sWAG) flooding for three-phase multicomponent compositional systems (LaForce and Orr, 2009). This work showed the surprising result that excessive water injection can interfere with the development of multicontact miscibility (MCM) between the oil and gas phases. Multicontact miscibility occurs when a combination of thermodynamics and flow through porous media cause the formation of a single hydrocarbon phase. When MCM occurs hydrocarbons are displaced from the reservoir much more efficiently than in an immiscible gas or water flood. This presentation will compare and contrast the predicted displacements to a variety of models for sWAG flooding, including injection of water and a first-contact miscible (FCM) gas, three-phase compositional systems with developed miscibility and inert water (the aqueous phase contains only water, and water exists in only the aqueous phase) and compositional systems with developed miscibility in which all of the hydrocarbon components partition between all of the phases, but the water remains in the aqueous phase. Simulated solutions for each of the models are compared with the analytical solutions for various injection mixtures. This analysis can be used
Study of monopropellants for electrothermal thrusters: Analytical task summary report
NASA Technical Reports Server (NTRS)
Kuenzly, J. D.; Grabbi, R.
1973-01-01
The feasibility of operating small thrust level electrothermal thrusters is determined with monopropellants other than MIL-grade hydrazine. The work scope includes analytical study, design and fabrication of demonstration thrusters, and an evaluation test program where monopropellants with freezing points lower than MIL-grade hydrazine are evaluated and characterized to determine their applicability to electrothermal thrusters for spacecraft attitude control. Results of propellant chemistry studies and performance analyses indicated that the most promising candidate monopropellants to be investigated are monomethylhydrazine, Aerozine-50, 77% hydrazine-23% hydrazine azide blend, and TRW formulated mixed hydrazine monopropellant (MHM) consisting of 35% hydrazine-50% monomethylhydrazine-15% ammonia.
Blanket optimization studies for Cascade
Meier, W.R.; Morse, E.C.
1985-02-28
A nonlinear, multivariable, blanket optimization technique is applied to the Cascade inertial confinement fusion reactor concept. The thickness of a two-zone blanket, which consists of a BeO multiplier region followed by a LiAlO/sub 2/ breeding region, is minimized subject to constraints on the tritium breeding ratio, neutron leakage, and heat generation rate in Al/SiC tendons that support the chamber wall.
NASA Astrophysics Data System (ADS)
Kéchichian, Jean A.
2011-06-01
An analytic form of the accelerations due to the luni-solar perturbations resolved along the rotating Euler-Hill frame is devised by using the expansion method. The addition of higher order terms to the main gravity gradient term linear in the spacecraft radial distance, carried out to the third order, provides a very high level of accuracy in accounting for the gravity perturbations experienced by a vehicle in orbit due to the sun and the moon. The nodal precession as well as the perigee advance of the lunar orbit is taken into account analytically by using the analytic lunar theory of de Pontécoulant. The analytic description of the apparent solar orbit and the motion of the moon remove the need to call an epherneris generator at each integration step during the numerical integration of the spacecraft trajectory, leading to the self-contained software for rapid and efficient optimal trajectory generation through iterations. Equinoctial elements are used to describe the spacecraft state and the luni-solar accelerations are given in terms of the apparent solar and lunar longitudes as well as Eulerian angles of the spacecraft orbit with respect to the inertial ecliptic system. The analysis is useful in optimal low-thrust orbit transfers complementing previous analyses carried out by this author, in which thrust and Earth zonal perturbations such as J2, J3 and J4 in terms of the nonsingular equinoctial elements are included.
Cogeneration Technology Alternatives Study (CTAS). Volume 2: Analytical approach
NASA Technical Reports Server (NTRS)
Gerlaugh, H. E.; Hall, E. W.; Brown, D. H.; Priestley, R. R.; Knightly, W. F.
1980-01-01
The use of various advanced energy conversion systems were compared with each other and with current technology systems for their savings in fuel energy, costs, and emissions in individual plants and on a national level. The ground rules established by NASA and assumptions made by the General Electric Company in performing this cogeneration technology alternatives study are presented. The analytical methodology employed is described in detail and is illustrated with numerical examples together with a description of the computer program used in calculating over 7000 energy conversion system-industrial process applications. For Vol. 1, see 80N24797.
An insight-based longitudinal study of visual analytics.
Saraiya, Purvi; North, Chris; Lam, Vy; Duca, Karen A
2006-01-01
Visualization tools are typically evaluated in controlled studies that observe the short-term usage of these tools by participants on preselected data sets and benchmark tasks. Though such studies provide useful suggestions, they miss the long-term usage of the tools. A longitudinal study of a bioinformatics data set analysis is reported here. The main focus of this work is to capture the entire analysis process that an analyst goes through from a raw data set to the insights sought from the data. The study provides interesting observations about the use of visual representations and interaction mechanisms provided by the tools, and also about the process of insight generation in general. This deepens our understanding of visual analytics, guides visualization developers in creating more effective visualization tools in terms of user requirements, and guides evaluators in designing future studies that are more representative of insights sought by users from their data sets.
[Practical features of the pre-analytical phase of the BIOAMBIENT.ES biomonitoring study].
Esteban, Marta; Ruiz-Moraga, Montserrat; Pérez-Gómez, Beatriz; Castaño, Argelia
2013-01-01
The fieldwork of BIOAMBIENT.ES was developed from March 2009 to July 2010. BIOAMBIENT.ES is a human biomonitoring study of environmental pollutants performed in Spain at the national level. This article aims to show the tasks performed before starting the fieldwork to ensure the quality of the samples and consequently the quality of the results. A total of 1,936 whole blood, serum and first-morning urine samples and 604 hair samples were collected from workers who attended the annual occupational health examination in 38 centers in the Peninsula, Ceuta and the Canary Islands. Before the fieldwork was started, the optimal sampling material and sample shipment was identified and fieldworkers were trained in their tasks. Due to the planning and organization of the pre-analytical phase, only 1% of the collected samples had to be rejected due to problem with spills, conservation, etc. In addition, the analyses conducted showed no pre-analytical interferences.
Noble gas encapsulation into carbon nanotubes: Predictions from analytical model and DFT studies
Balasubramani, Sree Ganesh; Singh, Devendra; Swathi, R. S.
2014-11-14
The energetics for the interaction of the noble gas atoms with the carbon nanotubes (CNTs) are investigated using an analytical model and density functional theory calculations. Encapsulation of the noble gas atoms, He, Ne, Ar, Kr, and Xe into CNTs of various chiralities is studied in detail using an analytical model, developed earlier by Hill and co-workers. The constrained motion of the noble gas atoms along the axes of the CNTs as well as the off-axis motion are discussed. Analyses of the forces, interaction energies, acceptance and suction energies for the encapsulation enable us to predict the optimal CNTs that can encapsulate each of the noble gas atoms. We find that CNTs of radii 2.98 − 4.20 Å (chiral indices, (5,4), (6,4), (9,1), (6,6), and (9,3)) can efficiently encapsulate the He, Ne, Ar, Kr, and Xe atoms, respectively. Endohedral adsorption of all the noble gas atoms is preferred over exohedral adsorption on various CNTs. The results obtained using the analytical model are subsequently compared with the calculations performed with the dispersion-including density functional theory at the M06 − 2X level using a triple-zeta basis set and good qualitative agreement is found. The analytical model is however found to be computationally cheap as the equations can be numerically programmed and the results obtained in comparatively very less time.
NASA Astrophysics Data System (ADS)
Gaetano, A.; Roncolato, J.; Montorfano, D.; Barbato, M. C.; Ambrosetti, G.; Pedretti, A.
2016-05-01
The employment of new gaseous heat transfer fluids as air or CO2, which are cheaper and environmentally friendly, is drawing more and more attention within the field of Concentrated Solar Power applications. However, despite the advantages, their use requires receivers with a larger heat transfer area and flow cross section with a consequent greater volume of thermal insulation. Solid thermal insulations currently used present high thermal inertia which is energetically penalizing during the daily transient phases faced by the main plant components (e.g. receivers). With the aim of overcoming this drawback a thermal insulation based on radiative shields is presented in this study. Starting from an initial layout comprising a solid thermal insulation layer, the geometry was optimized avoiding the use of the solid insulation keeping performance and fulfilling the geometrical constraints. An analytical Matlab model was implemented to assess the system thermal behavior in terms of heat loss taking into account conductive, convective and radiative contributions. Accurate 2D Computational Fluid Dynamics (CFD) simulations were run to validate the Matlab model which was then used to select the most promising among three new different designs.
Aerodynamic optimization studies on advanced architecture computers
NASA Technical Reports Server (NTRS)
Chawla, Kalpana
1995-01-01
The approach to carrying out multi-discipline aerospace design studies in the future, especially in massively parallel computing environments, comprises of choosing (1) suitable solvers to compute solutions to equations characterizing a discipline, and (2) efficient optimization methods. In addition, for aerodynamic optimization problems, (3) smart methodologies must be selected to modify the surface shape. In this research effort, a 'direct' optimization method is implemented on the Cray C-90 to improve aerodynamic design. It is coupled with an existing implicit Navier-Stokes solver, OVERFLOW, to compute flow solutions. The optimization method is chosen such that it can accomodate multi-discipline optimization in future computations. In the work , however, only single discipline aerodynamic optimization will be included.
Analytical optimal pulse shapes obtained with the aid of genetic algorithms
NASA Astrophysics Data System (ADS)
Guerrero, Rubén D.; Arango, Carlos A.; Reyes, Andrés
2015-09-01
We propose a methodology to design optimal pulses for achieving quantum optimal control on molecular systems. Our approach constrains pulse shapes to linear combinations of a fixed number of experimentally relevant pulse functions. Quantum optimal control is obtained by maximizing a multi-target fitness function using genetic algorithms. As a first application of the methodology, we generated an optimal pulse that successfully maximized the yield on a selected dissociation channel of a diatomic molecule. Our pulse is obtained as a linear combination of linearly chirped pulse functions. Data recorded along the evolution of the genetic algorithm contained important information regarding the interplay between radiative and diabatic processes. We performed a principal component analysis on these data to retrieve the most relevant processes along the optimal path. Our proposed methodology could be useful for performing quantum optimal control on more complex systems by employing a wider variety of pulse shape functions.
Analytical optimal pulse shapes obtained with the aid of genetic algorithms
Guerrero, Rubén D.; Arango, Carlos A.; Reyes, Andrés
2015-09-28
We propose a methodology to design optimal pulses for achieving quantum optimal control on molecular systems. Our approach constrains pulse shapes to linear combinations of a fixed number of experimentally relevant pulse functions. Quantum optimal control is obtained by maximizing a multi-target fitness function using genetic algorithms. As a first application of the methodology, we generated an optimal pulse that successfully maximized the yield on a selected dissociation channel of a diatomic molecule. Our pulse is obtained as a linear combination of linearly chirped pulse functions. Data recorded along the evolution of the genetic algorithm contained important information regarding the interplay between radiative and diabatic processes. We performed a principal component analysis on these data to retrieve the most relevant processes along the optimal path. Our proposed methodology could be useful for performing quantum optimal control on more complex systems by employing a wider variety of pulse shape functions.
Analytical study of the critical behavior of the nonlinear pendulum
NASA Astrophysics Data System (ADS)
Lima, F. M. S.
2010-11-01
The dynamics of a simple pendulum consisting of a small bob and a massless rigid rod has three possible regimes depending on its total energy E: Oscillatory (when E is not enough for the pendulum to reach the top position), "perpetual ascent" when E is exactly the energy needed to reach the top, and nonoscillatory for greater energies. In the latter regime, the pendulum rotates periodically without velocity inversions. In contrast to the oscillatory regime, for which an exact analytic solution is known, the other two regimes are usually studied by solving the equation of motion numerically. By applying conservation of energy, I derive exact analytical solutions to both the perpetual ascent and nonoscillatory regimes and an exact expression for the pendulum period in the nonoscillatory regime. Based on Cromer's approximation for the large-angle pendulum period, I find a simple approximate expression for the decrease of the period with the initial velocity in the nonoscillatory regime, valid near the critical velocity. This expression is used to study the critical slowing down, which is observed near the transition between the oscillatory and nonoscillatory regimes.
Factor analytic study of the personality of female methadone outpatients.
Duthie, R B
1980-10-01
Several researchers have examined the personality of chemical abusers by employing a multivariate clustering strategy. All of these studies focused on hospitalized inpatient addicts. Only one included females in the study. The purpose of this study is to examine the transposed data factor analytically derived profiles of female methadone maintained outpatients. All clients were given the Mini-Mult short form version of the Minnesota Multiphasic Personality Inventory. Seventy profiles were randomly selected from 130 female profiles. Program Factor of the Analyses of Behavioral Sciences Data program series was employed in statistically processing this data. Descriptions of the five factors are provided. Most of the profile types seem to fall into the normal or personality disordered categories. Forth-two percent of the profiles were normal, 24% were Personality Disorders, 6% were Neurotic, and 28% were unclassified using five factors.
DeBaun, M.R.; Sox, H.C. Jr. )
1991-07-01
Erythrocyte protoporphyrin (EP) was introduced in the 1970s as an inexpensive screening test for lead poisoning. As greater knowledge of lead poisoning has accumulated, the recommended EP level at which further evaluation for lead poisoning should be initiated has been lowered from greater than or equal to 50 micrograms/dL to greater than or equal to 35 micrograms/dL. The purpose of this study was to evaluate the utility of this EP threshold. A receiver operator characteristic curve was constructed to assess the relationship between the true-positive rate and false-positive rate of EP at various decision thresholds. The receiver operator characteristic curve was constructed with data from the second National Health and Nutrition Examination Survey from 1976 to 1980, which included 2673 children 6 years of age or younger who had both blood lead and EP level determinations. Decision analysis was then used to determine the optimal EP decision threshold for detecting a blood lead level greater than or equal to 25 micrograms/dL. The receiver operator characteristic curve demonstrated that EP is a poor predictor of a blood lead level greater than or equal to 25 micrograms/dL. At the currently recommended EP decision threshold of 35 micrograms/dL, the true-positive rates and false-positive rates of EP are 0.23 and 0.04, respectively. As a result of the inadequate performance of EP screening for lead poisoning, when the prevalence of lead poisoning is greater than 8%, there is no EP decision threshold that optimizes the relationship between the cost of screening normal children and the benefit of detecting lead-poisoned children. Erythrocyte protoporphyrin measurement is not sufficiently sensitive to be recommended uniformly as a screening test for lead poisoning.
Vehicle systems design optimization study
NASA Technical Reports Server (NTRS)
Gilmour, J. L.
1980-01-01
The optimum vehicle configuration and component locations are determined for an electric drive vehicle based on using the basic structure of a current production subcompact vehicle. The optimization of an electric vehicle layout requires a weight distribution in the range of 53/47 to 62/38 in order to assure dynamic handling characteristics comparable to current internal combustion engine vehicles. Necessary modification of the base vehicle can be accomplished without major modification of the structure or running gear. As long as batteries are as heavy and require as much space as they currently do, they must be divided into two packages, one at front under the hood and a second at the rear under the cargo area, in order to achieve the desired weight distribution. The weight distribution criteria requires the placement of batteries at the front of the vehicle even when the central tunnel is used for the location of some batteries. The optimum layout has a front motor and front wheel drive. This configuration provides the optimum vehicle dynamic handling characteristics and the maximum passenger and cargo space for a given size vehicle.
Vehicle systems design optimization study
Gilmour, J. L.
1980-04-01
The optimization of an electric vehicle layout requires a weight distribution in the range of 53/47 to 62/38 in order to assure dynamic handling characteristics comparable to current production internal combustion engine vehicles. It is possible to achieve this goal and also provide passenger and cargo space comparable to a selected current production sub-compact car either in a unique new design or by utilizing the production vehicle as a base. Necessary modification of the base vehicle can be accomplished without major modification of the structure or running gear. As long as batteries are as heavy and require as much space as they currently do, they must be divided into two packages - one at front under the hood and a second at the rear under the cargo area - in order to achieve the desired weight distribution. The weight distribution criteria requires the placement of batteries at the front of the vehicle even when the central tunnel is used for the location of some batteries. The optimum layout has a front motor and front wheel drive. This configuration provides the optimum vehicle dynamic handling characteristics and the maximum passsenger and cargo space for a given size vehicle.
Analytical study of acoustically perturbed Brillouin active magnetized semiconductor plasma
Shukla, Arun; Jat, K. L.
2015-07-31
An analytical study of acoustically perturbed Brillouin active magnetized semiconductor plasma has been reported. In the present analytical investigation, the lattice displacement, acousto-optical polarization, susceptibility, acousto-optical gain constant arising due to the induced nonlinear current density and acousto-optical process are deduced in an acoustically perturbed Brillouin active magnetized semiconductor plasma using the hydrodynamical model of plasma and coupled mode scheme. The influence of wave number and magnetic field has been explored. The analysis has been applied to centrosymmetric crystal. Numerical estimates are made for n-type InSb crystal duly irradiated by a frequency doubled 10.6 µm CO{sub 2} laser. It is found that lattice displacement, susceptibility and acousto-optical gain increase linearly with incident wave number and applied dc magnetic field, while decrease with scattering angle. The gain also increases with electric amplitude of incident laser beam. Results are found to be well in agreement with available literature.
Hinojo, M J; Medina, A; Valle-Algarra, F M; Gimeno-Adelantado, J V; Jiménez, M; Mateo, R
2006-04-01
Fumonisin B1 (FB1) and fumonisin B2 (FB2) are the main members of a family of mycotoxins produced by various fungal species belonging to the Gibberella fujikuroi complex. The present work shows the results of a comparative study of various clean-up and derivatization procedures for analysis of fumonisins in rice cultures. Fumonisins were extracted from rice with acetonitrile/water (50/50, v/v). For clean-up, three solid-phase extraction procedures were assayed (C18 cartridge, SAX cartridge, and a combination of both). Two reagents (o-phthaldialdehyde and 4-fluoro-7-nitro-benzofurazan) were studied comparatively for formation of fluorescent derivatives. The separation was carried out by LC using a fluorescence detector. The best procedure for analysis of fumonisins in rice involved clean-up with C18 cartridge and derivatization with o-phthaldialdehyde. The limit of detection was 0.010 mg kg(-1) for both toxins. In the 10-500 mg kg(-1) spiking level range, the recovery rates for FB1 and FB2 in rice varied from 94.6% to 103.6% and from 96.3% to 101.9%, respectively. The optimized analytical method for determination of fumonisins in rice was applied to the study of FB1 and FB2 production by four isolates of the G. fujikuroi species complex in rice cultures carried out at different temperatures and water activities to establish the influence of strain and environmental conditions on fumonisin production in this cereal. In general, fumonisin production was the highest at 20 degrees C and lowest at 37 degrees C. Four of the five assayed water activity (aw) values (0.97, 0.98, 0.99, and 1.0) did not affect significantly fumonisin accumulation but fumonisins were not detected in cultures when aw was 0.96.
Design optimization studies using COSMIC NASTRAN
NASA Technical Reports Server (NTRS)
Pitrof, Stephen M.; Bharatram, G.; Venkayya, Vipperla B.
1993-01-01
The purpose of this study is to create, test and document a procedure to integrate mathematical optimization algorithms with COSMIC NASTRAN. This procedure is very important to structural design engineers who wish to capitalize on optimization methods to ensure that their design is optimized for its intended application. The OPTNAST computer program was created to link NASTRAN and design optimization codes into one package. This implementation was tested using two truss structure models and optimizing their designs for minimum weight, subject to multiple loading conditions and displacement and stress constraints. However, the process is generalized so that an engineer could design other types of elements by adding to or modifying some parts of the code.
Optimized interpolations and nonlinearity in numerical studies of woodwind instruments
NASA Astrophysics Data System (ADS)
Skouroupathis, Apostolos
2005-04-01
The impedance spectra of woodwind instruments with arbitrary axisymmetric geometry are studied. Piecewise interpolations of the instruments' profile are performed, using interpolating functions amenable to analytic solutions of the Webster equation. Our algorithm optimizes on the choice of such functions, while ensuring compatibility of wave-fronts at the joining points. Employing a standard mathematical model of a single-reed mouthpiece, as well as the time-domain reflection function which is derived from our impedance results, the Schumacher equation is solved for the pressure evolution in time. Analytic checks are made to verify that, despite the nonlinearity in the reed model and in the evolution equation, solutions are unique and singularity-free.
Analytical methods for kinetic studies of biological interactions: A review.
Zheng, Xiwei; Bi, Cong; Li, Zhao; Podariu, Maria; Hage, David S
2015-09-10
The rates at which biological interactions occur can provide important information concerning the mechanism and behavior of these processes in living systems. This review discusses several analytical methods that can be used to examine the kinetics of biological interactions. These techniques include common or traditional methods such as stopped-flow analysis and surface plasmon resonance spectroscopy, as well as alternative methods based on affinity chromatography and capillary electrophoresis. The general principles and theory behind these approaches are examined, and it is shown how each technique can be utilized to provide information on the kinetics of biological interactions. Examples of applications are also given for each method. In addition, a discussion is provided on the relative advantages or potential limitations of each technique regarding its use in kinetic studies.
An analytical study of electric vehicle handling dynamics
NASA Technical Reports Server (NTRS)
Greene, J. E.; Segal, D. J.
1979-01-01
Hypothetical electric vehicle configurations were studied by applying available analytical methods. Elementary linearized models were used in addition to a highly sophisticated vehicle dynamics computer simulation technique. Physical properties of specific EV's were defined for various battery and powertrain packaging approaches applied to a range of weight distribution and inertial properties which characterize a generic class of EV's. Computer simulations of structured maneuvers were performed for predicting handling qualities in the normal driving range and during various extreme conditions related to accident avoidance. Results indicate that an EV with forward weight bias will possess handling qualities superior to a comparable EV that is rear-heavy or equally balanced. The importance of properly matching tires, suspension systems, and brake system front/rear torque proportioning to a given EV configuration during the design stage is demonstrated.
Thermal analytical study of polyamide copolymer/Surlyn Ionomers Blends
Qin, C.; Ding, Y.P.
1993-12-31
Thermal analytical technique was used as a screening method to study polyamide(Nylon)/ethylene-co-methacrylic acid copolymer-based ionomer(Surlyn)blends. The retardation of crystallization process from molten state of Nylon-12 by the existence of the ionomer was observed, but the crystallization of Nylon-12 can not be thwarted even at high concentration of ionomers. Zinc ionomers shows stronger effect than sodium ionomers. A Nylon copolymer, polyamide-6,6-co-polyamide-6,10, was used to blend with different ionomers and the crystallization process from molten state of Nylon copolymer could be thwarted at high concentration of zinc ionomer even at very cooling rate. Interesting cold crystallization behavior of polyamide copolymer was observed during second DSC heating cycle in the temperature range of the melting process of ionomer.
Analytical methods for kinetic studies of biological interactions: A review.
Zheng, Xiwei; Bi, Cong; Li, Zhao; Podariu, Maria; Hage, David S
2015-09-10
The rates at which biological interactions occur can provide important information concerning the mechanism and behavior of these processes in living systems. This review discusses several analytical methods that can be used to examine the kinetics of biological interactions. These techniques include common or traditional methods such as stopped-flow analysis and surface plasmon resonance spectroscopy, as well as alternative methods based on affinity chromatography and capillary electrophoresis. The general principles and theory behind these approaches are examined, and it is shown how each technique can be utilized to provide information on the kinetics of biological interactions. Examples of applications are also given for each method. In addition, a discussion is provided on the relative advantages or potential limitations of each technique regarding its use in kinetic studies. PMID:25700721
ANALYTICAL METHODS FOR KINETIC STUDIES OF BIOLOGICAL INTERACTIONS: A REVIEW
Zheng, Xiwei; Bi, Cong; Li, Zhao; Podariu, Maria; Hage, David S.
2015-01-01
The rates at which biological interactions occur can provide important information concerning the mechanism and behavior of these processes in living systems. This review discusses several analytical methods that can be used to examine the kinetics of biological interactions. These techniques include common or traditional methods such as stopped-flow analysis and surface plasmon resonance spectroscopy, as well as alternative methods based on affinity chromatography and capillary electrophoresis. The general principles and theory behind these approaches are examined, and it is shown how each technique can be utilized to provide information on the kinetics of biological interactions. Examples of applications are also given for each method. In addition, a discussion is provided on the relative advantages or potential limitations of each technique regarding its use in kinetic studies. PMID:25700721
Analytical studies of spectrum broadcast structures in quantum Brownian motion
NASA Astrophysics Data System (ADS)
Tuziemski, J.; Korbicz, J. K.
2016-11-01
Spectrum broadcast structures are a new and fresh concept in the quantum-to-classical transition, introduced recently in the context of decoherence and the appearance of objective features in quantum mechanics. These are specific quantum state structures, responsible for the objectivization of the decohered state of a system. Recently, they have been demonstrated by means of the well-known quantum Brownian motion model of the recoilless limit (infinitely massive central system), as the principal interest lies in information transfer from the system to the environment. However, a final analysis relied on numerics. Here, after a presentation of the main concepts, we perform analytical studies of the model, showing the timescales and the efficiency of the spectrum broadcast structure formation. We consider a somewhat simplified environment, being random with a uniform distribution of frequencies.
Lubbad, Said H
2016-04-22
Poly(methyl styrene-co-bis(p-vinylbenzyl)dimethylsilane)-based monolithic capillary columns were optimized for separation of low, medium, and high molecular-weight analytes. The morphology and consequently the chromatographic performance of these monoliths were tuned by changes in the volume-ratio of monomer to macroporogen, establishing good monolithic flow-through and retention pores. Two monoliths were prepared and analyzed by reversed-phase chromatographic separation of low molecular-weight analytes such as alkyl benzenes and β-blockers, as well as medium and high molecular-weight analytes such as peptides and proteins, respectively. The microstructure was studied by scanning electron microscopy (SEM), and by inverse-size exclusion chromatography (ISEC). Monolith 1 demonstrated a high retention of alkyl benzenes, which coeluted from the column at the washing step of absolute acetonitrile; yet this monolith established a baseline separation of 9-peptide and 8-protein mixtures. Monolith 2 demonstrated efficient separation of the three analyte groups of different molecular weights. Six alkyl benzenes and five β-blockers were base-line separated in less than 5 and 2min, respectively, with good resolution and very small values of peak width at half height. Moreover, a comparable performance of efficient separation of the 9-peptide mixture and a fast separation of 5- and 8-protein mixtures were achieved. Both monoliths were characterized by high mechanical strength, high permeability, and excellent reproducibility. PMID:27016117
Lubbad, Said H
2016-04-22
Poly(methyl styrene-co-bis(p-vinylbenzyl)dimethylsilane)-based monolithic capillary columns were optimized for separation of low, medium, and high molecular-weight analytes. The morphology and consequently the chromatographic performance of these monoliths were tuned by changes in the volume-ratio of monomer to macroporogen, establishing good monolithic flow-through and retention pores. Two monoliths were prepared and analyzed by reversed-phase chromatographic separation of low molecular-weight analytes such as alkyl benzenes and β-blockers, as well as medium and high molecular-weight analytes such as peptides and proteins, respectively. The microstructure was studied by scanning electron microscopy (SEM), and by inverse-size exclusion chromatography (ISEC). Monolith 1 demonstrated a high retention of alkyl benzenes, which coeluted from the column at the washing step of absolute acetonitrile; yet this monolith established a baseline separation of 9-peptide and 8-protein mixtures. Monolith 2 demonstrated efficient separation of the three analyte groups of different molecular weights. Six alkyl benzenes and five β-blockers were base-line separated in less than 5 and 2min, respectively, with good resolution and very small values of peak width at half height. Moreover, a comparable performance of efficient separation of the 9-peptide mixture and a fast separation of 5- and 8-protein mixtures were achieved. Both monoliths were characterized by high mechanical strength, high permeability, and excellent reproducibility.
NASA Astrophysics Data System (ADS)
Liang, Guanhao; Wang, Yancheng; Mei, Deqing; Xi, Kailun; Chen, Zichen
2015-03-01
This paper presents a modified analytical model to study the sensing performance of a flexible capacitive tactile sensor array, which utilizes solid polydimethylsiloxane (PDMS) film as the dielectric layer. To predict the deformation of the sensing unit and capacitance changes, each sensing unit is simplified into a three-layer plate structure and divided into central, edge and corner regions. The plate structure and the three regions are studied by the general and modified models, respectively. For experimental validation, the capacitive tactile sensor array with 8 × 8 (= 64) sensing units is fabricated. Experiments are conducted by measuring the capacitance changes versus applied external forces and compared with the general and modified models’ predictions. For the developed tactile sensor array, the sensitivity predicted by the modified analytical model is 1.25%/N, only 0.8% discrepancy from the experimental measurement. Results demonstrate that the modified analytical model can accurately predict the sensing performance of the sensor array and could be utilized for model-based optimal capacitive tactile sensor array design.
NASA Astrophysics Data System (ADS)
Roy Choudhury, Raja; Roy Choudhury, Arundhati; Kanti Ghose, Mrinal
2013-01-01
A semi-analytical model with three optimizing parameters and a novel non-Gaussian function as the fundamental modal field solution has been proposed to arrive at an accurate solution to predict various propagation parameters of graded-index fibers with less computational burden than numerical methods. In our semi analytical formulation the optimization of core parameter U which is usually uncertain, noisy or even discontinuous, is being calculated by Nelder-Mead method of nonlinear unconstrained minimizations as it is an efficient and compact direct search method and does not need any derivative information. Three optimizing parameters are included in the formulation of fundamental modal field of an optical fiber to make it more flexible and accurate than other available approximations. Employing variational technique, Petermann I and II spot sizes have been evaluated for triangular and trapezoidal-index fibers with the proposed fundamental modal field. It has been demonstrated that, the results of the proposed solution identically match with the numerical results over a wide range of normalized frequencies. This approximation can also be used in the study of doped and nonlinear fiber amplifier.
STRengthening Analytical Thinking for Observational Studies: the STRATOS initiative
Sauerbrei, Willi; Abrahamowicz, Michal; Altman, Douglas G; le Cessie, Saskia; Carpenter, James
2014-01-01
The validity and practical utility of observational medical research depends critically on good study design, excellent data quality, appropriate statistical methods and accurate interpretation of results. Statistical methodology has seen substantial development in recent times. Unfortunately, many of these methodological developments are ignored in practice. Consequently, design and analysis of observational studies often exhibit serious weaknesses. The lack of guidance on vital practical issues discourages many applied researchers from using more sophisticated and possibly more appropriate methods when analyzing observational studies. Furthermore, many analyses are conducted by researchers with a relatively weak statistical background and limited experience in using statistical methodology and software. Consequently, even ‘standard’ analyses reported in the medical literature are often flawed, casting doubt on their results and conclusions. An efficient way to help researchers to keep up with recent methodological developments is to develop guidance documents that are spread to the research community at large. These observations led to the initiation of the strengthening analytical thinking for observational studies (STRATOS) initiative, a large collaboration of experts in many different areas of biostatistical research. The objective of STRATOS is to provide accessible and accurate guidance in the design and analysis of observational studies. The guidance is intended for applied statisticians and other data analysts with varying levels of statistical education, experience and interests. In this article, we introduce the STRATOS initiative and its main aims, present the need for guidance documents and outline the planned approach and progress so far. We encourage other biostatisticians to become involved. PMID:25074480
STRengthening analytical thinking for observational studies: the STRATOS initiative.
Sauerbrei, Willi; Abrahamowicz, Michal; Altman, Douglas G; le Cessie, Saskia; Carpenter, James
2014-12-30
The validity and practical utility of observational medical research depends critically on good study design, excellent data quality, appropriate statistical methods and accurate interpretation of results. Statistical methodology has seen substantial development in recent times. Unfortunately, many of these methodological developments are ignored in practice. Consequently, design and analysis of observational studies often exhibit serious weaknesses. The lack of guidance on vital practical issues discourages many applied researchers from using more sophisticated and possibly more appropriate methods when analyzing observational studies. Furthermore, many analyses are conducted by researchers with a relatively weak statistical background and limited experience in using statistical methodology and software. Consequently, even 'standard' analyses reported in the medical literature are often flawed, casting doubt on their results and conclusions. An efficient way to help researchers to keep up with recent methodological developments is to develop guidance documents that are spread to the research community at large. These observations led to the initiation of the strengthening analytical thinking for observational studies (STRATOS) initiative, a large collaboration of experts in many different areas of biostatistical research. The objective of STRATOS is to provide accessible and accurate guidance in the design and analysis of observational studies. The guidance is intended for applied statisticians and other data analysts with varying levels of statistical education, experience and interests. In this article, we introduce the STRATOS initiative and its main aims, present the need for guidance documents and outline the planned approach and progress so far. We encourage other biostatisticians to become involved.
Analytical and Numerical Studies of Coherent Field Configurations
NASA Astrophysics Data System (ADS)
Muller, Hans-Reinhard
Motivated by the goal of investigating the dynamics of the electroweak phase transition in the early Universe, a study of dynamical aspects of nonlinear field-theoretical systems is performed. Symmetric and asymmetric double-well potentials in the φ4 theory are used as a model for these systems. In the first part, it is shown that in this model, a class of localized, time-dependent, spherically-symmetric objects dubbed oscillons exists. The most distinctive feature of these objects is that they are extremely long-lived. The properties of oscillons are studied by numerical and analytical means. In the second part of the study, the matching between (1+1)-dimensional nonlinear field theories coupled to an external stochastic environment and their lattice simulations is investigated. In particular, a method is developed to obtain numerical results which are lattice-spacing independent, and to extract the correct effective potential which emerges from the simulations. As an application, the thermal production of kinks is studied, obtaining the lattice-spacing independent number density of kinks and the effective barrier for kink production, i.e., the effective kink mass. Within its range of validity, the approach can be used to match numerical simulations to continuum studies of the emergence of coherent field structures in cosmology and condensed matter physics.
Optimization of a coaxial electron cyclotron resonance plasma thruster with an analytical model
Cannat, F. E-mail: felix.cannat@gmail.com; Lafleur, T.; Jarrige, J.; Elias, P.-Q.; Packan, D.; Chabert, P.
2015-05-15
A new cathodeless plasma thruster currently under development at Onera is presented and characterized experimentally and analytically. The coaxial thruster consists of a microwave antenna immersed in a magnetic field, which allows electron heating via cyclotron resonance. The magnetic field diverges at the thruster exit and forms a nozzle that accelerates the quasi-neutral plasma to generate a thrust. Different thruster configurations are tested, and in particular, the influence of the source diameter on the thruster performance is investigated. At microwave powers of about 30 W and a xenon flow rate of 0.1 mg/s (1 SCCM), a mass utilization of 60% and a thrust of 1 mN are estimated based on angular electrostatic probe measurements performed downstream of the thruster in the exhaust plume. Results are found to be in fair agreement with a recent analytical helicon thruster model that has been adapted for the coaxial geometry used here.
Analytical study of ultrasound influence on the molten metals atomization
NASA Astrophysics Data System (ADS)
Antonnikova, A.; Arkhipov, V.; Boiko, V.; Basalaev, S.; Konovalenko, A.; Zolotorev, N.
2016-04-01
This paper focuses on the study of influence of ultrasound on liquid atomization using ejection nozzles. Two principles of influence of ultrasound on the atomization process such as a change of conditions on gas-liquid boundary during the generation of ultrasound oscillation in the gas and liquid jet (film) disintegration under the action of capillary forces in cases of generation of ultrasound oscillation in the liquid are considered. The optimal values of the ultrasound oscillation frequencies are calculated. Two constructions of the nozzles patented are proposed.
Insight and Action Analytics: Three Case Studies to Consider
ERIC Educational Resources Information Center
Milliron, Mark David; Malcolm, Laura; Kil, David
2014-01-01
Civitas Learning was conceived as a community of practice, bringing together forward-thinking leaders from diverse higher education institutions to leverage insight and action analytics in their ongoing efforts to help students learn well and finish strong. We define insight and action analytics as drawing, federating, and analyzing data from…
Chen, Xinhua; Zhou, Jiankang; Shen, Weimin
2016-09-01
Wavefront coding system can realize defocus invariance of PSF/OTF with a phase mask inserting in the pupil plane. Ideally, the derivative of the PSF/OTF with respect to defocus error should be close to zero as much as possible over the extended depth of field/focus for the wavefront coding system. In this paper, we propose an analytical expression for the computation of the derivative of PSF. With this expression, the derivative of PSF based merit function can be used in the optimization of the wavefront coding system with any type of phase mask and aberrations. Computation of the derivative of PSF using the proposed expression and FFT respectively are compared and discussed. We also demonstrate the optimization of a generic polynomial phase mask in wavefront coding system as an example. PMID:27607710
Zatsiorsky, Vladimir M.
2011-01-01
One of the key problems of motor control is the redundancy problem, in particular how the central nervous system (CNS) chooses an action out of infinitely many possible. A promising way to address this question is to assume that the choice is made based on optimization of a certain cost function. A number of cost functions have been proposed in the literature to explain performance in different motor tasks: from force sharing in grasping to path planning in walking. However, the problem of uniqueness of the cost function(s) was not addressed until recently. In this article, we analyze two methods of finding additive cost functions in inverse optimization problems with linear constraints, so-called linear-additive inverse optimization problems. These methods are based on the Uniqueness Theorem for inverse optimization problems that we proved recently (Terekhov et al., J Math Biol 61(3):423–453, 2010). Using synthetic data, we show that both methods allow for determining the cost function. We analyze the influence of noise on the both methods. Finally, we show how a violation of the conditions of the Uniqueness Theorem may lead to incorrect solutions of the inverse optimization problem. PMID:21311907
Terekhov, Alexander V; Zatsiorsky, Vladimir M
2011-02-01
One of the key problems of motor control is the redundancy problem, in particular how the central nervous system (CNS) chooses an action out of infinitely many possible. A promising way to address this question is to assume that the choice is made based on optimization of a certain cost function. A number of cost functions have been proposed in the literature to explain performance in different motor tasks: from force sharing in grasping to path planning in walking. However, the problem of uniqueness of the cost function(s) was not addressed until recently. In this article, we analyze two methods of finding additive cost functions in inverse optimization problems with linear constraints, so-called linear-additive inverse optimization problems. These methods are based on the Uniqueness Theorem for inverse optimization problems that we proved recently (Terekhov et al., J Math Biol 61(3):423-453, 2010). Using synthetic data, we show that both methods allow for determining the cost function. We analyze the influence of noise on the both methods. Finally, we show how a violation of the conditions of the Uniqueness Theorem may lead to incorrect solutions of the inverse optimization problem. PMID:21311907
Terekhov, Alexander V; Zatsiorsky, Vladimir M
2011-02-01
One of the key problems of motor control is the redundancy problem, in particular how the central nervous system (CNS) chooses an action out of infinitely many possible. A promising way to address this question is to assume that the choice is made based on optimization of a certain cost function. A number of cost functions have been proposed in the literature to explain performance in different motor tasks: from force sharing in grasping to path planning in walking. However, the problem of uniqueness of the cost function(s) was not addressed until recently. In this article, we analyze two methods of finding additive cost functions in inverse optimization problems with linear constraints, so-called linear-additive inverse optimization problems. These methods are based on the Uniqueness Theorem for inverse optimization problems that we proved recently (Terekhov et al., J Math Biol 61(3):423-453, 2010). Using synthetic data, we show that both methods allow for determining the cost function. We analyze the influence of noise on the both methods. Finally, we show how a violation of the conditions of the Uniqueness Theorem may lead to incorrect solutions of the inverse optimization problem.
Optimal pleurodesis: a comparison study.
Bresticker, M A; Oba, J; LoCicero, J; Greene, R
1993-02-01
With the resurgence of thoracoscopy, there is renewed interest in less invasive methods of pleurodesis. We wished to compare in an animal model a variety of methods suggested in reports. The purpose of the study was to rank the effectiveness of each procedure against the standard mechanical pleurodesis. Twenty-five mongrel dogs (weight, 25 to 35 kg) underwent bilateral thoracotomy. Each animal was randomly assigned to receive two of the following methods of pleurodesis: tetracycline, talc, mechanical abrasion, neodymium: yttrium-aluminum garnet (Nd:YAG) laser (Hereus Inc, E. Rutherford, NJ) photocoagulation, and argon beam coagulator (ABC) (Beacon Lab, Bloomfield, CO) electrocoagulation of the parietal pleura. At evaluation at 30 +/- 2 days, the efficacy of pleurodesis was graded on a scale of 0 to 4, with 0 representing a complete absence of pleural symphysis and 4 the adhesion of more than one lobe to both the chest wall and mediastinum. Mean grade and standard deviation of each method were: talc, 3.0 +/- 0.67; mechanical, 3.0 +/- 0.82; tetracycline, 2.3 +/- 1.4; ABC, 1.5 +/- 0.97; and Nd:YAG laser, 0.7 +/- 0.95. Both the talc and mechanical methods were superior to either the Nd:YAG laser or the ABC (p < 0.01). In this study, neither the Nd:YAG laser nor the ABC proved efficacious in producing pleurodesis. Talc poudrage is the only method of pleural symphysis comparable with mechanical abrasion.
Optimal pleurodesis: a comparison study.
Bresticker, M A; Oba, J; LoCicero, J; Greene, R
1993-02-01
With the resurgence of thoracoscopy, there is renewed interest in less invasive methods of pleurodesis. We wished to compare in an animal model a variety of methods suggested in reports. The purpose of the study was to rank the effectiveness of each procedure against the standard mechanical pleurodesis. Twenty-five mongrel dogs (weight, 25 to 35 kg) underwent bilateral thoracotomy. Each animal was randomly assigned to receive two of the following methods of pleurodesis: tetracycline, talc, mechanical abrasion, neodymium: yttrium-aluminum garnet (Nd:YAG) laser (Hereus Inc, E. Rutherford, NJ) photocoagulation, and argon beam coagulator (ABC) (Beacon Lab, Bloomfield, CO) electrocoagulation of the parietal pleura. At evaluation at 30 +/- 2 days, the efficacy of pleurodesis was graded on a scale of 0 to 4, with 0 representing a complete absence of pleural symphysis and 4 the adhesion of more than one lobe to both the chest wall and mediastinum. Mean grade and standard deviation of each method were: talc, 3.0 +/- 0.67; mechanical, 3.0 +/- 0.82; tetracycline, 2.3 +/- 1.4; ABC, 1.5 +/- 0.97; and Nd:YAG laser, 0.7 +/- 0.95. Both the talc and mechanical methods were superior to either the Nd:YAG laser or the ABC (p < 0.01). In this study, neither the Nd:YAG laser nor the ABC proved efficacious in producing pleurodesis. Talc poudrage is the only method of pleural symphysis comparable with mechanical abrasion. PMID:8431042
On biomolecules and semiconductors: Analytical studies of interface dynamics
NASA Astrophysics Data System (ADS)
Slavin, John William Joseph
The studies discussed here were undertaken to examine the use of III-V semiconducting materials as templates for biomolecules, to be applied in such technologies as Field-Effect Transistor (FET) and Light-emitting Diode (LED) biosensors. Materials application requires an informed analysis of interactions between chemical environments. Specific to surfaces, this means investigating the molecular interactions between the substrate and the bonding moieties. The analytical tools used to probe these interactions, and the changes that such communication causes on specific substrates are specifically discussed. Surface analysis tools included in this review are Atomic Force Microscopy (AFM), Nanoindentation, X-ray Photoelectron Spectroscopy (XPS), and Raman Microscopy. The interaction of biomolecules - deoxyribonucleic acid (DNA), proteins adhered to nanoparticles, and amino acids - on semiconductor surfaces is also examined. Proper investigation follows, as well, the methods of applying these biomolecular structures to the specified surfaces, through procedures such as solution phase transfer, as well as Dip-pen Nanolithography (DPN). The stretching and enzymatic cleavage of DNA, on silicon oxide surfaces, was studied to determine the recognition properties of dual-enzymatic systems on surfaces. Fundamental questions such as the interaction of functional groups with InAs(100) surfaces, the mechanical properties of protein modified systems, and the DPN application of biologically relevant linker molecules to InAs(100) surfaces were explored. These studies provide information applicable to the development of novel sensing platforms in the future.
Numerical simulations and analytical studies of collapsing spheres
NASA Astrophysics Data System (ADS)
Foster, Prudence Nichols
We investigate the spherical self-gravitating collapse of two scenarios. In the first, used to study star formation, we assume the gas remains isothermal. In the second, used in cooling flow studies, we assume the gas is radiatively cooling. In both cases, we compare numerical hydrodynamic evolutions with analytical solutions. In the star formation problem our simulations begin close to hydrostatic equilibrium. For initial conditions with a central density plateau, supersonic infall velocities develop. At core formation, near the origin, the central density diverges approaching an r-2 profile, and the infall velocity approaches -3.3 times the speed of sound. These are characteristics of the Larson Penston self-similar solution, although in the analytical solution these conditions would apply at all radii. After core formation, these initial conditions lead to a decreasing mass accretion rate. Other initial configurations with larger initial outer cloud radii to core radius ratios, i.e. in excess of 20, will develop constant mass accretion rates after core formation. This agrees with the self-similar solutions developed by Shu. Assuming optical transparency, we calculate line profiles for the computed collapse and find that the supersonic velocities do affect the line profiles near the time of core formation. The second problem we address is radiatively cooling self-gravitating flows. We find a self-similar solution that describes the flow, with characteristics in common with the gravothermal catastrophe studied in the context of globular clusters. Our analysis applies to the early transitional stage of cluster cooling flows, as the gas evolves from a static medium to a steady state inflow. The self-similar solution incorporates a power law cooling term which is inversely proportional to rho2 Tlamda;if lambda is less than 1 the central temperature increases with time. This is confirmed with numerical simulations for lambda less than or equal to -0.5 that have
Systematic analytical and numerical studies of highly correlated electron systems
NASA Astrophysics Data System (ADS)
Tsai, Shan-Wen
Strong electron correlations in condensed matter systems give rise to a wide range of striking physical properties, producing phenomena as varied as high temperature superconductivity, metal-insulator transitions and the integer and fractional quantum Hall effects. Quantum critical systems also exhibit strong correlations between a large number of degrees of freedom. In this thesis we study these complicated systems using a combination of analytical and numerical approaches. We perform systematic investigations, which adds to the robustness of our results. We develop a new method, based on the density-matrix renormalization-group (DMRG) algorithm combined with finite-size scaling analysis, to study critical behavior in quantum spin chains and extract critical exponents. Accurate results are obtained for spin-1/2 antiferromagnetic chains and the spin-1 chain at the critical point separating the Haldane and the dimerized phases. Disorder in a system can change its properties drastically. Plateau transitions in the integer quantum Hall effect provide the clearest example of quantum critical behavior in a disordered system. We provide analytical proof that the Chalker-Coddington model, which is used to describe the plateau transitions, is quantum critical. Starting from a field theory based on this model, equivalent to a non-Hermitian supersymmetric spin chain, we prove quantum criticality by a Lieb-Schultz-Mattis type theorem. This approach was motivated by numerical results obtained using the DMRG/finite-size scaling method. Our generalized LSM theorem also applies to the spin quantum Hall effect, which can appear in disordered d-wave superconductors with broken time-reversal symmetry. The last part of the thesis is a renormalization-group study of two dimensional interacting electron systems. We obtain results relevant to high-temperature superconductors and also to the family of kappa - (BEDT - TTF)2X organic superconductors. At half filling, the fully nested
Optimization of solar assisted heat pump systems via a simple analytic approach
Andrews, J W
1980-01-01
An analytic method for calculating the optimum operating temperature of the collector/storage subsystem in a solar assisted heat pump is presented. A tradeoff exists between rising heat pump coefficient of performance and falling collector efficiency as this temperature is increased, resulting in an optimum temperature whose value increases with increasing efficiency of the auxiliary energy source. Electric resistance is shown to be a poor backup to such systems. A number of options for thermally coupling the system to the ground are analyzed and compared.
Modeling of dispersed-drug delivery from planar polymeric systems: optimizing analytical solutions.
Helbling, Ignacio M; Ibarra, Juan C D; Luna, Julio A; Cabrera, María I; Grau, Ricardo J A
2010-11-15
Analytical solutions for the case of controlled dispersed-drug release from planar non-erodible polymeric matrices, based on Refined Integral Method, are presented. A new adjusting equation is used for the dissolved drug concentration profile in the depletion zone. The set of equations match the available exact solution. In order to illustrate the usefulness of this model, comparisons with experimental profiles reported in the literature are presented. The obtained results show that the model can be employed in a broad range of applicability.
a Multidisciplinary Analytical Framework for Studying Active Mobility Patterns
NASA Astrophysics Data System (ADS)
Orellana, D.; Hermida, C.; Osorio, P.
2016-06-01
Intermediate cities are urged to change and adapt their mobility systems from a high energy-demanding motorized model to a sustainable low-motorized model. In order to accomplish such a model, city administrations need to better understand active mobility patterns and their links to socio-demographic and cultural aspects of the population. During the last decade, researchers have demonstrated the potential of geo-location technologies and mobile devices to gather massive amounts of data for mobility studies. However, the analysis and interpretation of this data has been carried out by specialized research groups with relatively narrow approaches from different disciplines. Consequently, broader questions remain less explored, mainly those relating to spatial behaviour of individuals and populations with their geographic environment and the motivations and perceptions shaping such behaviour. Understanding sustainable mobility and exploring new research paths require an interdisciplinary approach given the complex nature of mobility systems and their social, economic and environmental impacts. Here, we introduce the elements for a multidisciplinary analytical framework for studying active mobility patterns comprised of three components: a) Methodological, b) Behavioural, and c) Perceptual. We demonstrate the applicability of the framework by analysing mobility patterns of cyclists and pedestrians in an intermediate city integrating a range of techniques, including: GPS tracking, spatial analysis, auto-ethnography, and perceptual mapping. The results demonstrated the existence of non-evident spatial behaviours and how perceptual features affect mobility. This knowledge is useful for developing policies and practices for sustainable mobility planning.
Inertial drives for micro- and nanorobots: analytical study
NASA Astrophysics Data System (ADS)
Buechi, Roland; Zesch, Wolfgang; Codourey, Alain; Siegwart, Roland Y.
1995-12-01
The need for high precision robots dedicated to the assembly of microsystems has led to the design of new kinds of actuators able to reach very high positional accuracy over large distances. Among these, inertial sliders have received considerably interest in the last years. They have the advantage of being based on a simple principle that leads to a simple mechanical design. However, because they are based on the nonlinearity of friction, it is not easy to predict their stepsize repeatability. In order to understand the most important parameters affecting the precision of inertial drives, a theoretical study of a 1 degree of freedom inertial slider has been established. Analytical formulas describing the influence of different parameters, such as static and dynamic friction and mass distribution, have been developed. The effect of applied functions (sawtooth and parabolic), have also been studied. The theoretical cut off frequency has been found for each of the different waveforms, allowing us to predict the maximal and minimal working frequencies for the system. Thus, for each curve form, the repeatability of inertial sliders can be evaluated taking into account the uncertainties in the friction coefficients. The best suited waveforms for given constraints can therefore be selected. Simulations carried out from this have been successfully compared to experimental results.
Analytical study of Saint Gregory Nazianzen Icon, Old Cairo, Egypt
NASA Astrophysics Data System (ADS)
Issa, Yousry M.; Abdel-Maksoud, Gomaa; Magdy, Mina
2015-11-01
The study aims to evaluate the state of icon through characterization of the icon layers (ground, paint and varnish layers) and to provide tools for assessment the impact of aging and environmental conditions in order to produce some solutions for conservation of the icon. Analytical techniques used in this study were attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), field emission scanning electron microscope-energy dispersive X ray spectroscopy (FESEM-EDX) and amino acid analyzer (AAA). The results obtained revealed that gypsum and lead white were used for ground layer. The identified pigments were lamp carbon black, brown ochre, Prussian blue, yellow ochre and gold leaf. Egg yolk was the binder used with most of pigments and animal glue was used with gold color. The varnish used was shellac resin. It was concluded that stable pigments gave permanent colors and environmental conditions had an influence on promotion of oxidation process. Auto-oxidation of binder and varnish materials occurred by the action of pigment components and light result in cracking of the paint film and fading of the varnish glaze.
An analytical study of various telecomminication networks using markov models
NASA Astrophysics Data System (ADS)
Ramakrishnan, M.; Jayamani, E.; Ezhumalai, P.
2015-04-01
The main aim of this paper is to examine issues relating to the performance of various Telecommunication networks, and applied queuing theory for better design and improved efficiency. Firstly, giving an analytical study of queues deals with quantifying the phenomenon of waiting lines using representative measures of performances, such as average queue length (on average number of customers in the queue), average waiting time in queue (on average time to wait) and average facility utilization (proportion of time the service facility is in use). In the second, using Matlab simulator, summarizes the finding of the investigations, from which and where we obtain results and describing methodology for a) compare the waiting time and average number of messages in the queue in M/M/1 and M/M/2 queues b) Compare the performance of M/M/1 and M/D/1 queues and study the effect of increasing the number of servers on the blocking probability M/M/k/k queue model.
A Comprehensive Feasibility Study of Marine CSEM Using Analytical Calculation
NASA Astrophysics Data System (ADS)
Furukawa, T.; Lee, K. H.; Yamane, K.
2010-12-01
The main purpose of marine controlled source electromagnetic (CSEM) sounding is to find subsurface resistive reservoir and thus reduce risk before drilling. The CSEM response, usually in the form of electric field, recorded by seafloor receivers along one or several survey lines have been used to detect subsurface resistors and rank prospects initially defined from seismic data. The CSEM forward modeling plays an important role in sensitivity studies, survey design and data interpretation. A number of 3-D modeling techniques has recently been reported, but only 1-D forward modeling provides analytical solutions using numerical integration. Based on EM1D originally developed at Lawrence Berkeley National Laboratory, we made some improvements in the following subjects. First, the accuracy of the solution has been improved especially when the source-receiver separation (offset) is large. The need for better accuracy stems from the fact that the sensitivity requirement in detecting a thin resistive layer in marine CSEM survey, potential indicator of hydrocarbon zone, is on the order of 10-15Volt/m. This is a very small number to deal with requiring highly accurate solutions. Second, transverse isotropy in electrical resistivity has been implemented so that one or more layers can have anisotropy to simulate vertically compressed sedimentary sections. Using such modified code, we investigate the sensitivity of a thin resistive, and/or transversely isotropic, hydrocarbon reservoir to marine CSEM methods. Both the time-domain and the frequency-domain responses are investigated.
NASA Astrophysics Data System (ADS)
Boisson, F.; Bekaert, V.; Reilhac, A.; Wurtz, J.; Brasse, D.
2015-03-01
In SPECT imaging, improvement or deterioration of performance is mostly due to collimator design. Classical SPECT systems mainly use parallel hole or pinhole collimators. Rotating slat collimators (RSC) can be an interesting alternative to optimize the tradeoff between detection efficiency and spatial resolution. The present study was conducted using a RSC system for small animal imaging called CLiR. The CLiR system was used in planar mode only. In a previous study, planar 2D projections were reconstructed using the well-known filtered backprojection algorithm (FBP). In this paper, we investigated the use of the statistical reconstruction algorithm maximum likelihood expectation maximization (MLEM) to reconstruct 2D images with the CLiR system using a probability matrix calculated using an analytic approach. The primary objective was to propose a method to quickly generate a light system matrix, which facilitates its handling and storage, while providing accurate and reliable performance. Two other matrices were calculated using GATE Monte Carlo simulations to investigate the performance obtained using the matrix calculated analytically. The first matrix calculated using GATE took all the physics processes into account, where the second did not consider for the scattering, as the analytical matrix did not take this physics process into account either. 2D images were reconstructed using FBP and MLEM with the three different probability matrices. Both simulated and experimental data were used. A comparative study of these images was conducted using different metrics: the modulation transfert function, the signal-to-noise ratio and quantification measurement. All the results demonstrated the suitability of using a probability matrix calculated analytically. It provided similar results in terms of spatial resolution (about 0.6 mm with differences <5%), signal-to-noise ratio (differences <10%), or quality of image.
Boisson, F; Bekaert, V; Reilhac, A; Wurtz, J; Brasse, D
2015-03-21
In SPECT imaging, improvement or deterioration of performance is mostly due to collimator design. Classical SPECT systems mainly use parallel hole or pinhole collimators. Rotating slat collimators (RSC) can be an interesting alternative to optimize the tradeoff between detection efficiency and spatial resolution. The present study was conducted using a RSC system for small animal imaging called CLiR. The CLiR system was used in planar mode only. In a previous study, planar 2D projections were reconstructed using the well-known filtered backprojection algorithm (FBP). In this paper, we investigated the use of the statistical reconstruction algorithm maximum likelihood expectation maximization (MLEM) to reconstruct 2D images with the CLiR system using a probability matrix calculated using an analytic approach. The primary objective was to propose a method to quickly generate a light system matrix, which facilitates its handling and storage, while providing accurate and reliable performance. Two other matrices were calculated using GATE Monte Carlo simulations to investigate the performance obtained using the matrix calculated analytically. The first matrix calculated using GATE took all the physics processes into account, where the second did not consider for the scattering, as the analytical matrix did not take this physics process into account either. 2D images were reconstructed using FBP and MLEM with the three different probability matrices. Both simulated and experimental data were used. A comparative study of these images was conducted using different metrics: the modulation transfert function, the signal-to-noise ratio and quantification measurement. All the results demonstrated the suitability of using a probability matrix calculated analytically. It provided similar results in terms of spatial resolution (about 0.6 mm with differences <5%), signal-to-noise ratio (differences <10%), or quality of image. PMID:25716556
Balbo, Andrea; Minor, Kenneth H; Velikovsky, Carlos A; Mariuzza, Roy A; Peterson, Cynthia B; Schuck, Peter
2005-01-01
Protein interactions can promote the reversible assembly of multiprotein complexes, which have been identified as critical elements in many regulatory processes in cells. The biophysical characterization of assembly products, their number and stoichiometry, and the dynamics of their interactions in solution can be very difficult. A classical first-principle approach for the study of purified proteins and their interactions is sedimentation velocity analytical ultracentrifugation. This approach allows one to distinguish different protein complexes based on their migration in the centrifugal field without isolating reversibly formed complexes from the individual components. An important existing limitation for systems with multiple components and assembly products is the identification of the species associated with the observed sedimentation rates. We developed a computational approach for integrating multiple optical signals into the sedimentation coefficient distribution analysis of components, which combines the size-dependent hydrodynamic separation with discrimination of the extinction properties of the sedimenting species. This approach allows one to deduce the stoichiometry and to assign the identity of the assembly products without prior assumptions of the number of species and the nature of their interaction. Although chromophoric labels may be used to enhance the spectral resolution, we demonstrate the ability to work label-free for three-component protein mixtures. We observed that the spectral discrimination can synergistically enhance the hydrodynamic resolution. This method can take advantage of differences in the absorbance spectra of interacting solution components, for example, for the study of protein-protein, protein-nucleic acid or protein-small molecule interactions, and can determine the size, hydrodynamic shape, and stoichiometry of multiple complexes in solution.
Systematic analytical characterization of new psychoactive substances: A case study.
Lobo Vicente, Joana; Chassaigne, Hubert; Holland, Margaret V; Reniero, Fabiano; Kolář, Kamil; Tirendi, Salvatore; Vandecasteele, Ine; Vinckier, Inge; Guillou, Claude
2016-08-01
New psychoactive substances (NPS) are synthesized compounds that are not usually covered by European and/or international laws. With a slight alteration in the chemical structure of existing illegal substances registered in the European Union (EU), these NPS circumvent existing controls and are thus referred to as "legal highs". They are becoming increasingly available and can easily be purchased through both the internet and other means (smart shops). Thus, it is essential that the identification of NPS keeps up with this rapidly evolving market. In this case study, the Belgian Customs authorities apprehended a parcel, originating from China, containing two samples, declared as being "white pigments". For routine identification, the Belgian Customs Laboratory first analysed both samples by gas-chromatography mass-spectrometry and Fourier-Transform Infrared spectroscopy. The information obtained by these techniques is essential and can give an indication of the chemical structure of an unknown substance but not the complete identification of its structure. To bridge this gap, scientific and technical support is ensured by the Joint Research Centre (JRC) to the European Commission Directorate General for Taxation and Customs Unions (DG TAXUD) and the Customs Laboratory European Network (CLEN) through an Administrative Arrangement for fast recognition of NPS and identification of unknown chemicals. The samples were sent to the JRC for a complete characterization using advanced techniques and chemoinformatic tools. The aim of this study was also to encourage the development of a science-based policy driven approach on NPS. These samples were fully characterized and identified as 5F-AMB and PX-3 using (1)H and (13)C nuclear magnetic resonance (NMR), high-resolution tandem mass-spectrometry (HR-MS/MS) and Raman spectroscopy. A chemoinformatic platform was used to manage, unify analytical data from multiple techniques and instruments, and combine it with chemical and
Systematic analytical characterization of new psychoactive substances: A case study.
Lobo Vicente, Joana; Chassaigne, Hubert; Holland, Margaret V; Reniero, Fabiano; Kolář, Kamil; Tirendi, Salvatore; Vandecasteele, Ine; Vinckier, Inge; Guillou, Claude
2016-08-01
New psychoactive substances (NPS) are synthesized compounds that are not usually covered by European and/or international laws. With a slight alteration in the chemical structure of existing illegal substances registered in the European Union (EU), these NPS circumvent existing controls and are thus referred to as "legal highs". They are becoming increasingly available and can easily be purchased through both the internet and other means (smart shops). Thus, it is essential that the identification of NPS keeps up with this rapidly evolving market. In this case study, the Belgian Customs authorities apprehended a parcel, originating from China, containing two samples, declared as being "white pigments". For routine identification, the Belgian Customs Laboratory first analysed both samples by gas-chromatography mass-spectrometry and Fourier-Transform Infrared spectroscopy. The information obtained by these techniques is essential and can give an indication of the chemical structure of an unknown substance but not the complete identification of its structure. To bridge this gap, scientific and technical support is ensured by the Joint Research Centre (JRC) to the European Commission Directorate General for Taxation and Customs Unions (DG TAXUD) and the Customs Laboratory European Network (CLEN) through an Administrative Arrangement for fast recognition of NPS and identification of unknown chemicals. The samples were sent to the JRC for a complete characterization using advanced techniques and chemoinformatic tools. The aim of this study was also to encourage the development of a science-based policy driven approach on NPS. These samples were fully characterized and identified as 5F-AMB and PX-3 using (1)H and (13)C nuclear magnetic resonance (NMR), high-resolution tandem mass-spectrometry (HR-MS/MS) and Raman spectroscopy. A chemoinformatic platform was used to manage, unify analytical data from multiple techniques and instruments, and combine it with chemical and
NASA Astrophysics Data System (ADS)
Cody, B. M.; Gonzalez-Nicolas, A.; Bau, D. A.
2011-12-01
Carbon capture and storage (CCS) has been proposed as a method of reducing global carbon dioxide (CO2) emissions. Although CCS has the potential to greatly retard greenhouse gas loading to the atmosphere while cleaner, more sustainable energy solutions are developed, there is a possibility that sequestered CO2 may leak and intrude into and adversely affect groundwater resources. It has been reported [1] that, while CO2 intrusion typically does not directly threaten underground drinking water resources, it may cause secondary effects, such as the mobilization of hazardous inorganic constituents present in aquifer minerals and changes in pH values. These risks must be fully understood and minimized before CCS project implementation. Combined management of project resources and leakage risk is crucial for the implementation of CCS. In this work, we present a method of: (a) minimizing the total CCS cost, the summation of major project costs with the cost associated with CO2 leakage; and (b) maximizing the mass of injected CO2, for a given proposed sequestration site. Optimization decision variables include the number of CO2 injection wells, injection rates, and injection well locations. The capital and operational costs of injection wells are directly related to injection well depth, location, injection flow rate, and injection duration. The cost of leakage is directly related to the mass of CO2 leaked through weak areas, such as abandoned oil wells, in the cap rock layers overlying the injected formation. Additional constraints on fluid overpressure caused by CO2 injection are imposed to maintain predefined effective stress levels that prevent cap rock fracturing. Here, both mass leakage and fluid overpressure are estimated using two semi-analytical models based upon work by [2,3]. A multi-objective evolutionary algorithm coupled with these semi-analytical leakage flow models is used to determine Pareto-optimal trade-off sets giving minimum total cost vs. maximum mass
Analytical solution of the optimal three dimensional reentry problem using Chapman's exact equations
NASA Technical Reports Server (NTRS)
Vinh, N. X.; Busemann, A.; Culp, R. D.
1974-01-01
This paper presents the general solution for the optimal three dimensional aerodynamic control of a lifting vehicle entering a planetary atmosphere. A set of dimensionless variables is introduced, and the resulting exact equations of motion have the distinctive advantage that they are completely free of the physical characteristics of the vehicle. Furthermore, a general lift-drag polar is used to define the aerodynamic control. Hence, the results obtained apply to any type of vehicle of arbitrary weight, dimensions and shape, having an arbitrary polar and entering any planetary atmosphere.
Abou Mrad, Ninette; Duvernay, Fabrice; Theulé, Patrice; Chiavassa, Thierry; Danger, Grégoire
2014-08-19
This contribution presents an original analytical system for studying volatile organic compounds (VOC) coming from the heating and/or irradiation of interstellar/cometary ice analogues (VAHIIA system) through laboratory experiments. The VAHIIA system brings solutions to three analytical constraints regarding chromatography analysis: the low desorption kinetics of VOC (many hours) in the vacuum chamber during laboratory experiments, the low pressure under which they sublime (10(-9) mbar), and the presence of water in ice analogues. The VAHIIA system which we developed, calibrated, and optimized is composed of two units. The first is a preconcentration unit providing the VOC recovery. This unit is based on a cryogenic trapping which allows VOC preconcentration and provides an adequate pressure allowing their subsequent transfer to an injection unit. The latter is a gaseous injection unit allowing the direct injection into the GC-MS of the VOC previously transferred from the preconcentration unit. The feasibility of the online transfer through this interface is demonstrated. Nanomoles of VOC can be detected with the VAHIIA system, and the variability in replicate measurements is lower than 13%. The advantages of the GC-MS in comparison to infrared spectroscopy are pointed out, the GC-MS allowing an unambiguous identification of compounds coming from complex mixtures. Beyond the application to astrophysical subjects, these analytical developments can be used for all systems requiring vacuum/cryogenic environments.
Abou Mrad, Ninette; Duvernay, Fabrice; Theulé, Patrice; Chiavassa, Thierry; Danger, Grégoire
2014-08-19
This contribution presents an original analytical system for studying volatile organic compounds (VOC) coming from the heating and/or irradiation of interstellar/cometary ice analogues (VAHIIA system) through laboratory experiments. The VAHIIA system brings solutions to three analytical constraints regarding chromatography analysis: the low desorption kinetics of VOC (many hours) in the vacuum chamber during laboratory experiments, the low pressure under which they sublime (10(-9) mbar), and the presence of water in ice analogues. The VAHIIA system which we developed, calibrated, and optimized is composed of two units. The first is a preconcentration unit providing the VOC recovery. This unit is based on a cryogenic trapping which allows VOC preconcentration and provides an adequate pressure allowing their subsequent transfer to an injection unit. The latter is a gaseous injection unit allowing the direct injection into the GC-MS of the VOC previously transferred from the preconcentration unit. The feasibility of the online transfer through this interface is demonstrated. Nanomoles of VOC can be detected with the VAHIIA system, and the variability in replicate measurements is lower than 13%. The advantages of the GC-MS in comparison to infrared spectroscopy are pointed out, the GC-MS allowing an unambiguous identification of compounds coming from complex mixtures. Beyond the application to astrophysical subjects, these analytical developments can be used for all systems requiring vacuum/cryogenic environments. PMID:25025518
[Optimal formation conditions and analytical methods of the target product by MAP precipitation].
Hao, Xiao-Di; Lan, Li; Wang, Chong-Chen; van Loosdrecht, M C M
2009-04-15
In order to establish optimal conditions of the struvite (MAP: MgNH4PO4 x 6H2O) formation, acid dissolution was applied and developed to perform element analyses on the precipitates obtained from MAP precipitation, and a novel analyzing and calculating method was developed to quantitatively determine the struvite content (purity) in the harvested precipitates according to the NH4+-N content. With this method, the purities of struvite were respectively determined for both ultra pure water and tap water used as solutes. At the same time, the effect of pH and Ca2+ on the formation and crystallization of struvite was evaluated. The newly developed method was effective enough to determine the purities of struvite, which could be a better method than qualitative X-ray diffraction (XRD). Based on the developed method, it was found that the optimal pH ranges for having a high struvite content (> 90%) were respectively at 7.5-9.0 with ultra pure water as solute and at 7.0-7.5 with tap water as solute. In real wastewater, Ca2+ at pH > 8.0 might result in impurities rather than struvite. Therefore, a neutral pH range (< 8.0) is proposed to perform struvite precipitation in wastewater.
Beamforming and holography image formation methods: an analytic study.
Solimene, Raffaele; Cuccaro, Antonio; Ruvio, Giuseppe; Tapia, Daniel Flores; O'Halloran, Martin
2016-04-18
Beamforming and holographic imaging procedures are widely used in many applications such as radar sensing, sonar, and in the area of microwave medical imaging. Nevertheless, an analytical comparison of the methods has not been done. In this paper, the Point Spread Functions pertaining to the two methods are analytically determined. This allows a formal comparison of the two techniques, and to easily highlight how the performance depends on the conﬁguration parameters, including frequency range, number of scatterers, and data discretization. It is demonstrated that the beamforming and holography basically achieve the same resolution but beamforming requires a cheaper (less sensors) conﬁguration.. PMID:27137336
Beamforming and holography image formation methods: an analytic study.
Solimene, Raffaele; Cuccaro, Antonio; Ruvio, Giuseppe; Tapia, Daniel Flores; O'Halloran, Martin
2016-04-18
Beamforming and holographic imaging procedures are widely used in many applications such as radar sensing, sonar, and in the area of microwave medical imaging. Nevertheless, an analytical comparison of the methods has not been done. In this paper, the Point Spread Functions pertaining to the two methods are analytically determined. This allows a formal comparison of the two techniques, and to easily highlight how the performance depends on the conﬁguration parameters, including frequency range, number of scatterers, and data discretization. It is demonstrated that the beamforming and holography basically achieve the same resolution but beamforming requires a cheaper (less sensors) conﬁguration..
Structural and analytical studies of silica accumulations in Equisetum hyemale.
Sapei, Lanny; Gierlinger, Notburga; Hartmann, Jürgen; Nöske, Robert; Strauch, Peter; Paris, Oskar
2007-10-01
Horsetail (Equisetum spp.) is known as one of the strongest accumulators of silicon among higher terrestrial plants. We use the combination of position-resolved analytical techniques, namely microtomography, energy-dispersive X-Ray elemental mapping, Raman microscopy, as well as small-angle and wide-angle scattering of X-rays, to study the type, distribution and nanostructure of silica in the internodes of Equisetum hyemale. The predominant silicification pattern is a thin continuous layer on the entire outer epidermis with the highest density in particular knob regions of the long epidermal cells. The knob tips contain up to 33 wt% silicon in the form of pure hydrated amorphous silica, while the silica content is lower in the inner part of the knobs and on the continuous layer. In contrast to the knob tips, the silica in these regions lacks silanol groups and is proposed to be in close association with polysaccharides. No mentionable amount of crystalline silica is detected by wide-angle X-ray scattering. The small-angle X-ray scattering data are consistent with the presence of colloidal, sheet-like silica agglomerates with a thickness of about 2 nm. From these results we conclude that there are at least two distinct forms of silica in E. hyemale which may have different functions. The close association of silica with cell wall polymers suggests that they may act as a polymeric template that controls the shape and size of the colloidal silica particles similar to many other biominerals and mineralised tissues. We propose that owing to its specific distribution in E. hyemale, a protective role and possibly also an important biomechanical role are among the most likely functions of silica in these plants.
NASA Astrophysics Data System (ADS)
Nečemer, Marijan; Kump, Peter; Ščančar, Janez; Jaćimović, Radojko; Simčič, Jurij; Pelicon, Primož; Budnar, Miloš; Jeran, Zvonka; Pongrac, Paula; Regvar, Marjana; Vogel-Mikuš, Katarina
2008-11-01
Phytoremediation is an emerging technology that employs the use of higher plants for the clean-up of contaminated environments. Progress in the field is however handicapped by limited knowledge of the biological processes involved in plant metal uptake, translocation, tolerance and plant-microbe-soil interactions; therefore a better understanding of the basic biological mechanisms involved in plant/microbe/soil/contaminant interactions would allow further optimization of phytoremediation technologies. In view of the needs of global environmental protection, it is important that in phytoremediation and plant biology studies the analytical procedures for elemental determination in plant tissues and soil should be fast and cheap, with simple sample preparation, and of adequate accuracy and reproducibility. The aim of this study was therefore to present the main characteristics, sample preparation protocols and applications of X-ray fluorescence-based analytical techniques (energy dispersive X-ray fluorescence spectrometry—EDXRF, total reflection X-ray fluorescence spectrometry—TXRF and micro-proton induced X-ray emission—micro-PIXE). Element concentrations in plant leaves from metal polluted and non-polluted sites, as well as standard reference materials, were analyzed by the mentioned techniques, and additionally by instrumental neutron activation analysis (INAA) and atomic absorption spectrometry (AAS). The results were compared and critically evaluated in order to assess the performance and capability of X-ray fluorescence-based techniques in phytoremediation and plant biology studies. It is the EDXRF, which is recommended as suitable to be used in the analyses of a large number of samples, because it is multi-elemental, requires only simple preparation of sample material, and it is analytically comparable to the most frequently used instrumental chemical techniques. The TXRF is compatible to FAAS in sample preparation, but relative to AAS it is fast
Widdowson, M.A.; Chapelle, F.H.; Brauner, J.S.; ,
2003-01-01
A method is developed for optimizing monitored natural attenuation (MNA) and the reduction in the aqueous source zone concentration (??C) required to meet a site-specific regulatory target concentration. The mathematical model consists of two one-dimensional equations of mass balance for the aqueous phase contaminant, to coincide with up to two distinct zones of transformation, and appropriate boundary and intermediate conditions. The solution is written in terms of zone-dependent Peclet and Damko??hler numbers. The model is illustrated at a chlorinated solvent site where MNA was implemented following source treatment using in-situ chemical oxidation. The results demonstrate that by not taking into account a variable natural attenuation capacity (NAC), a lower target ??C is predicted, resulting in unnecessary source concentration reduction and cost with little benefit to achieving site-specific remediation goals.
A Cluster Analytic Study of Osteoprotective Behavior in Undergraduates
ERIC Educational Resources Information Center
Sharp, Katherine; Thombs, Dennis L.
2003-01-01
Objective: To derive an empirical taxonomy of osteoprotective stages using the Precaution Adoption Process Model (PAPM) and to identify the predisposing factors associated with each stage. Methods: An anonymous survey was completed by 504 undergraduates at a Midwestern public university. Results: Cluster analytic findings indicate that only 2…
Expanding Students' Analytical Frameworks through the Study of Graphic Novels
ERIC Educational Resources Information Center
Connors, Sean P.
2015-01-01
When teachers work with students to construct a metalanguage that they can draw on to describe and analyze graphic novels, and then invite students to apply that metalanguage in the service of composing multimodal texts of their own, teachers broaden students' analytical frameworks. In the process of doing so, teachers empower students. In this…
Numerical and Analytic Studies of Random-Walk Models.
NASA Astrophysics Data System (ADS)
Li, Bin
We begin by recapitulating the universality approach to problems associated with critical systems, and discussing the role that random-walk models play in the study of phase transitions and critical phenomena. As our first numerical simulation project, we perform high-precision Monte Carlo calculations for the exponents of the intersection probability of pairs and triplets of ordinary random walks in 2 dimensions, in order to test the conformal-invariance theory predictions. Our numerical results strongly support the theory. Our second numerical project aims to test the hyperscaling relation dnu = 2 Delta_4-gamma for self-avoiding walks in 2 and 3 dimensions. We apply the pivot method to generate pairs of self-avoiding walks, and then for each pair, using the Karp-Luby algorithm, perform an inner -loop Monte Carlo calculation of the number of different translates of one walk that makes at least one intersection with the other. Applying a least-squares fit to estimate the exponents, we have obtained strong numerical evidence that the hyperscaling relation is true in 3 dimensions. Our great amount of data for walks of unprecedented length(up to 80000 steps), yield a updated value for the end-to-end distance and radius of gyration exponent nu = 0.588 +/- 0.001 (95% confidence limit), which comes out in good agreement with the renormalization -group prediction. In an analytic study of random-walk models, we introduce multi-colored random-walk models and generalize the Symanzik and B.F.S. random-walk representations to the multi-colored case. We prove that the zero-component lambdavarphi^2psi^2 theory can be represented by a two-color mutually -repelling random-walk model, and it becomes the mutually -avoiding walk model in the limit lambda to infty. However, our main concern and major break-through lies in the study of the two-point correlation function for the lambda varphi^2psi^2 theory with N > 0 components. By representing it as a two-color random-walk expansion
Study and optimization of the spatial resolution for detectors with binary readout
NASA Astrophysics Data System (ADS)
Yonamine, R.; Maerschalk, T.; Lentdecker, G. De
2016-09-01
Using simulations and analytical approaches, we have studied single hit resolutions obtained with a binary readout, which is often proposed for high granularity detectors to reduce the generated data volume. Our simulations considering several parameters (e.g. strip pitch) show that the detector geometry and an electronics parameter of the binary readout chips could be optimized for binary readout to offer an equivalent spatial resolution to the one with an analog readout. To understand the behavior as a function of simulation parameters, we developed analytical models that reproduce simulation results with a few parameters. The models can be used to optimize detector designs and operation conditions with regard to the spatial resolution.
Analytical study of flow phenomena in SSME turnaround duct geometries
NASA Astrophysics Data System (ADS)
McLallin, K. L.
1985-04-01
The SSME fuel turbopump hot gas manifold was identified as a source of loss and flow distortion which significantly affects the performance and durability of both the drive turbine and the LOX injector area of the main combustion chamber. Two current SSME geometries were studied, the full power level (FPL) and the first manned orbital flight (FMOF) configuration. The effects of turnaround duct geometry on flow losses and distortions, by varying wall curvature and flow area variation in the 180 deg turnaround region were examined. The effects of the duct inlet flow phenomena such as the radial distortion of the inlet flow and inlet swirl level on turnaround duct performance were also investigated. It is shown that of the two current geometries, the FMOF configuration had lower pressure losses and generated less flow distortion, but had a small flow separation bubble at the 180 deg turnaround exit. It is found that by optimizing wall curvature and flow diffusion in the turnaround, improved duct performance can be achieved.
Lee, Eungkyu; Zhang, Teng; Hu, Ming; Luo, Tengfei
2016-06-22
Interfacial thermal resistance presents great challenges to the thermal management of modern electronics. In this work, we perform an analytical study to enhance the thermal boundary conductance (TBC) of nanostructured interfaces with square-shape pillar arrays, extendable to the characteristic lengths that can be fabricated in practice. As a representative system, we investigate a SiC substrate with the square-shape pillar array combined with epitaxial GaN as the nanostructured interface. By applying a first-order ray tracing method and molecular dynamics simulations to analyze phonon incidence and transmission at the nanostructured interface, we systematically study the impact of the characteristic dimensions of the pillar array on the TBC. Based on the multi-scale analysis we provide a general guideline to optimize the nanostructured interfaces to achieve higher TBC, demonstrating that the optimized TBC value of the nanostructured SiC/GaN interfaces can be 42% higher than that of the planar SiC/GaN interfaces without nanostructures. The model used and results obtained in this study will guide the further experimental realization of nanostructured interfaces for better thermal management in microelectronics. PMID:27275647
Review of Factor Analytic Studies Examining Symptoms of Autism Spectrum Disorders
ERIC Educational Resources Information Center
Shuster, Jill; Perry, Adrienne; Bebko, James; Toplak, Maggie E.
2014-01-01
Factor analytic studies have been conducted to examine the inter-relationships and degree of overlap among symptoms in Autism Spectrum Disorder (ASD). This paper reviewed 36 factor analytic studies that have examined ASD symptoms, using 13 different instruments. Studies were grouped into three categories: Studies with all DSM-IV symptoms, studies…
Analytical and experimental study on complex compressed air pipe network
NASA Astrophysics Data System (ADS)
Gai, Yushou; Cai, Maolin; Shi, Yan
2015-09-01
To analyze the working characteristics of complex compressed air networks, numerical methods are widely used which are based on finite element technology or intelligent algorithms. However, the effectiveness of the numerical methods is limited. In this paper, to provide a new method to optimize the design and the air supply strategy of the complex compressed air pipe network, firstly, a novel method to analyze the topology structure of the compressed air flow in the pipe network is initially proposed. A matrix is used to describe the topology structure of the compressed air flow. Moreover, based on the analysis of the pressure loss of the pipe network, the relationship between the pressure and the flow of the compressed air is derived, and a prediction method of pressure fluctuation and air flow in a segment in a complex pipe network is proposed. Finally, to inspect the effectiveness of the method, an experiment with a complex network is designed. The pressure and the flow of airflow in the network are measured and studied. The results of the study show that, the predicted results with the proposed method have a good consistency with the experimental results, and that verifies the air flow prediction method of the complex pipe network. This research proposes a new method to analyze the compressed air network and a prediction method of pressure fluctuation and air flow in a segment, which can predicate the fluctuation of the pressure according to the flow of compressed air, and predicate the fluctuation of the flow according to the pressure in a segment of a complex pipe network.
Analytical Studies of Boundary Layer Generated Aircraft Interior Noise
NASA Technical Reports Server (NTRS)
Howe, M. S.; Shah, P. L.
1997-01-01
An analysis is made of the "interior noise" produced by high, subsonic turbulent flow over a thin elastic plate partitioned into "panels" by straight edges transverse to the mean flow direction. This configuration models a section of an aircraft fuselage that may be regarded as locally flat. The analytical problem can be solved in closed form to represent the acoustic radiation in terms of prescribed turbulent boundary layer pressure fluctuations. Two cases are considered: (i) the production of sound at an isolated panel edge (i.e., in the approximation in which the correlation between sound and vibrations generated at neighboring edges is neglected), and (ii) the sound generated by a periodic arrangement of identical panels. The latter problem is amenable to exact analytical treatment provided the panel edge conditions are the same for all panels. Detailed predictions of the interior noise depend on a knowledge of the turbulent boundary layer wall pressure spectrum, and are given here in terms of an empirical spectrum proposed by Laganelli and Wolfe. It is expected that these analytical representations of the sound generated by simplified models of fluid-structure interactions can used to validate more general numerical schemes.
Bozkaya, Uğur; Sherrill, C. David
2014-11-28
Orbital-optimized MP2.5 [or simply “optimized MP2.5,” OMP2.5, for short] and its analytic energy gradients are presented. The cost of the presented method is as much as that of coupled-cluster singles and doubles (CCSD) [O(N{sup 6}) scaling] for energy computations. However, for analytic gradient computations the OMP2.5 method is only half as expensive as CCSD because there is no need to solve λ{sub 2}-amplitude equations for OMP2.5. The performance of the OMP2.5 method is compared with that of the standard second-order Møller–Plesset perturbation theory (MP2), MP2.5, CCSD, and coupled-cluster singles and doubles with perturbative triples (CCSD(T)) methods for equilibrium geometries, hydrogen transfer reactions between radicals, and noncovalent interactions. For bond lengths of both closed and open-shell molecules, the OMP2.5 method improves upon MP2.5 and CCSD by 38%–43% and 31%–28%, respectively, with Dunning's cc-pCVQZ basis set. For complete basis set (CBS) predictions of hydrogen transfer reaction energies, the OMP2.5 method exhibits a substantially better performance than MP2.5, providing a mean absolute error of 1.1 kcal mol{sup −1}, which is more than 10 times lower than that of MP2.5 (11.8 kcal mol{sup −1}), and comparing to MP2 (14.6 kcal mol{sup −1}) there is a more than 12-fold reduction in errors. For noncovalent interaction energies (at CBS limits), the OMP2.5 method maintains the very good performance of MP2.5 for closed-shell systems, and for open-shell systems it significantly outperforms MP2.5 and CCSD, and approaches CCSD(T) quality. The MP2.5 errors decrease by a factor of 5 when the optimized orbitals are used for open-shell noncovalent interactions, and comparing to CCSD there is a more than 3-fold reduction in errors. Overall, the present application results indicate that the OMP2.5 method is very promising for open-shell noncovalent interactions and other chemical systems with difficult electronic structures.
NASA Astrophysics Data System (ADS)
Bani-Hani, M. A.; Karami, M. A.
2015-09-01
This paper presents vibration analysis and structural optimization of a swimming-morphing structure. The swimming of the structure is achieved by utilization of piezoelectric patches to generate traveling waves. The third mode shape of the structure in the longitudinal direction resembles the body waveform of a swimming eel. After swimming to its destination, the morphing structure changes shape from an open box to a cube using shape memory alloys (SMAs). The SMAs used for the configuration change of the box robot cannot be used for swimming since they fail to operate at high frequencies. Piezoelectric patches are actuated at the third natural frequency of the structure. We optimize the thickness of the panels and the stiffness of the springs at the joints to generate swimming waveforms that most closely resemble the body waveform of an eel. The traveling wave is generated using two piezoelectric sets of patches bonded to the first and last segments of the beams in the longitudinal direction. Excitation of the piezoelectric results in coupled system dynamics equations that can be translated into the generation of waves. Theoretical analysis based on the distributed parameter model is conducted in this paper. A scalar measure of the traveling to standing wave ratio is introduced using a 2-dimensional Fourier transform (2D-FFT) of the body deformation waveform. An optimization algorithm based on tuning the flexural transverse wave is established to obtain a higher traveling to standing wave ratio. The results are then compared to common methods in the literature for assessment of standing to traveling wave ratios. The analytical models are verified by the close agreement between the traveling waves predicted by the model and those measured in the experiments.
Parameterizing Phrase Based Statistical Machine Translation Models: An Analytic Study
ERIC Educational Resources Information Center
Cer, Daniel
2011-01-01
The goal of this dissertation is to determine the best way to train a statistical machine translation system. I first develop a state-of-the-art machine translation system called Phrasal and then use it to examine a wide variety of potential learning algorithms and optimization criteria and arrive at two very surprising results. First, despite the…
Analytic and numerical studies of the modified betatron. [Kiloamp beams
Hughes, T.P.; Campbell, M.M.; Godfrey, B.B.
1983-08-01
The modified betatron concept has been proposed as a means of accelerating high current (kiloamp) electron beams to high energy. This device employs a toroidal magnetic field to overcome the space-charge limit on the current in a conventional betatron at low energy. In this paper, the authors look at the injection, equilibrium and stability of the modified betatron. The main emphasis is on stability. An analytic dispersion relation is derived using a cold-fluid model of the beam. The results are compared to three-dimensional simulations performed with the electromagnetic PIC code IVORY. The nonlinear development of the negative mass instability is followed in the simulations.
Analytical study of the twin-jet shielding
NASA Technical Reports Server (NTRS)
Gerhold, C. H.
1983-01-01
The development of the analytical model of twin-jet shielding is summarized. The models consist of a point noise source impinging on a cylinder of heated flow in which the temperature and flow velocity are uniform cross the cross section. In the formulation of the model, the wave equations are written for the regions outside the flow and within the flow cylinder. The solutions to the wave equations are matched at the jet boundary under the conditions of continuity of pressure and continuity of the vortex sheet. The solution reduces to an indefinite integral involving Bessel functions. The integral is solved approximately using a saddle point method.
An Optimization Study of Hot Stamping Operation
NASA Astrophysics Data System (ADS)
Ghoo, Bonyoung; Umezu, Yasuyoshi; Watanabe, Yuko; Ma, Ninshu; Averill, Ron
2010-06-01
In the present study, 3-dimensional finite element analyses for hot-stamping processes of Audi B-pillar product are conducted using JSTAMP/NV and HEEDS. Special attention is paid to the optimization of simulation technology coupling with thermal-mechanical formulations. Numerical simulation based on FEM technology and optimization design using the hybrid adaptive SHERPA algorithm are applied to hot stamping operation to improve productivity. The robustness of the SHERPA algorithm is found through the results of the benchmark example. The SHERPA algorithm is shown to be far superior to the GA (Genetic Algorithm) in terms of efficiency, whose calculation time is about 7 times faster than that of the GA. The SHERPA algorithm could show high performance in a large scale problem having complicated design space and long calculation time.
The Use of Analytic Rubric in the Assessment of Writing Performance--Inter-Rater Concordance Study
ERIC Educational Resources Information Center
Beyreli, Latif; Ari, Gokhan
2009-01-01
In this study, the purpose was to determine whether there was concordance among raters in the assessment of the writing performance using analytic rubric; furthermore, factors affecting the assessment process were examined. The analytic rubric used in the study consists of three sections and ten properties: External structure (format, spelling and…
Multivariate optimization of an analytical method for the analysis of dog and cat foods by ICP OES.
da Costa, Silvânio Silvério Lopes; Pereira, Ana Cristina Lima; Passos, Elisangela Andrade; Alves, José do Patrocínio Hora; Garcia, Carlos Alexandre Borges; Araujo, Rennan Geovanny Oliveira
2013-04-15
Experimental design methodology was used to optimize an analytical method for determination of the mineral element composition (Al, Ca, Cd, Cr, Cu, Ba, Fe, K, Mg, Mn, P, S, Sr and Zn) of dog and cat foods. Two-level full factorial design was applied to define the optimal proportions of the reagents used for microwave-assisted sample digestion (2.0 mol L(-1) HNO3 and 6% m/v H2O2). A three-level factorial design for two variables was used to optimize the operational conditions of the inductively coupled plasma optical emission spectrometer, employed for analysis of the extracts. A radiofrequency power of 1.2 kW and a nebulizer argon flow of 1.0 L min(-1) were selected. The limits of quantification (LOQ) were between 0.03 μg g(-1) (Cr, 267.716 nm) and 87 μg g(-1) (Ca, 373.690 nm). The trueness of the optimized method was evaluated by analysis of five certified reference materials (CRMs): wheat flour (NIST 1567a), bovine liver (NIST 1577), peach leaves (NIST 1547), oyster tissue (NIST 1566b), and fish protein (DORM-3). The recovery values obtained for the CRMs were between 80 ± 4% (Cr) and 117 ± 5% (Cd), with relative standard deviations (RSDs) better than 5%, demonstrating that the proposed method offered good trueness and precision. Ten samples of pet food (five each of cat and dog food) were acquired at supermarkets in Aracaju city (Sergipe State, Brazil). Concentrations in the dog food ranged between 7.1 mg kg(-1) (Ba) and 2.7 g kg(-1) (Ca), while for cat food the values were between 3.7 mg kg(-1) (Ba) and 3.0 g kg(-1) (Ca). The concentrations of Ca, K, Mg, P, Cu, Fe, Mn, and Zn in the food were compared with the guidelines of the United States' Association of American Feed Control Officials (AAFCO) and the Brazilian Ministry of Agriculture, Livestock, and Food Supply (Ministério da Agricultura, Pecuária e Abastecimento-MAPA).
Analytical study on mesocarbon microbeads derived from coal tar pitch
Zhang, Y.; Murata, S.; Nomura, M.
1999-07-01
Pitches have been recognized as excellent precursors for carbon materials and their properties are considered to be influential on the properties and function of carbon material. For this reason, their detailed characterization is being required. Successful pitch characterization must satisfy the following points: (1) very complicated pitches can be clearly distinguished; (2) the performance of the final carbon product can be predicted by characterizing the precursor pitch at its molecular level; and (3) a satisfactory explanation can be provided for chemical and physical behavior of pitches for a given utilization process based on their structural differences. Successful pitch characterization is quite difficult to be attained because pitches are very complex mixtures containing several hundred compounds with different functionalities. Thus, the methods for their characterization are limited to the measurements of average structural parameters, such as softening point (SP), H/C atomic ratio, quinoline- and toluene-insoluble (QI and TI) fractions, aromaticity, carbon yield, etc.. Although these parameters can give a fairly good evaluation about pitch quality, they can not always explain why pitches with similar characteristics on traditional characterization techniques display a significantly different behavior. This fact provides a challenging subject in the field of pitch characterization. At the same time, there is a possibility that in a given case satisfactory important factors remain undetected due to the limitation of analytical techniques, thus leading to serious problems in the pitch utilization. Therefore, it seems to be essential to know, for a given utilization of pitches, which of the pitch properties normally measured is important and how this affects the behavior of pitch. Another serious difficulty in pitch characterization is the fact that pitches are normally not completely soluble in solvents. There is no single analytical technique which can
NASA Astrophysics Data System (ADS)
Taneja, Jayant Kumar
Electricity is an indispensable commodity to modern society, yet it is delivered via a grid architecture that remains largely unchanged over the past century. A host of factors are conspiring to topple this dated yet venerated design: developments in renewable electricity generation technology, policies to reduce greenhouse gas emissions, and advances in information technology for managing energy systems. Modern electric grids are emerging as complex distributed systems in which a portfolio of power generation resources, often incorporating fluctuating renewable resources such as wind and solar, must be managed dynamically to meet uncontrolled, time-varying demand. Uncertainty in both supply and demand makes control of modern electric grids fundamentally more challenging, and growing portfolios of renewables exacerbate the challenge. We study three electricity grids: the state of California, the province of Ontario, and the country of Germany. To understand the effects of increasing renewables, we develop a methodology to scale renewables penetration. Analyzing these grids yields key insights about rigid limits to renewables penetration and their implications in meeting long-term emissions targets. We argue that to achieve deep penetration of renewables, the operational model of the grid must be inverted, changing the paradigm from load-following supplies to supply-following loads. To alleviate the challenge of supply-demand matching on deeply renewable grids, we first examine well-known techniques, including altering management of existing supply resources, employing utility-scale energy storage, targeting energy efficiency improvements, and exercising basic demand-side management. Then, we create several instantiations of supply-following loads -- including refrigerators, heating and cooling systems, and laptop computers -- by employing a combination of sensor networks, advanced control techniques, and enhanced energy storage. We examine the capacity of each load
Analytical structural efficiency studies of borsic/aluminum compression panels
NASA Technical Reports Server (NTRS)
Mcwithey, R. R.
1976-01-01
Analytically determined mass-strength curves, strain-strength curves, and dimensions are presented for structurally efficient hat-stiffened panels, corrugation-stiffened panels, hat-stiffened honeycomb-core sandwich panels, open-section corrugation panels, and honeycomb-core sandwich panels. The panels were assumed to be fabricated from either titanium, borsic/aluminum, or a combination of these materials. Borsic/aluminum panels and titanium panels reinforced with borsic/aluminum were lighter and stiffer than comparably designed titanium panels. Reinforced titanium panels had the same extensional stiffness as comparably designed Borsic/aluminum panels. For a given load, the structural efficiency of the hat-stiffened honeycomb-core sandwich panel was higher than the structural efficiency of the other stiffened panels.
Analytical study of diffraction effects in extremely large segmented telescopes.
Yaitskova, Natalia; Dohlen, Kjetil; Dierickx, Philippe
2003-08-01
We present an analysis of the diffraction effects from a segmented aperture with a very large number of segments-prototype of the next generation of extremely large telescopes. This analysis is based on the point-spread-function analytical calculation for Keck-type hexagonal segmentation geometry. We concentrate on the effects that lead to the appearance of speckles and/or a regular pattern of diffraction peaks. These effects are related to random piston and tip-tilt errors on each segment, gaps between segments, and segment edge distortion. We deliver formulas and the typical numerical values for the Strehl ratio, the relative intensity of higher-order diffraction peaks, and the averaged intensity of speckles associated with each particular case of segmentation error. PMID:12938912
Analytical study of diffraction effects in extremely large segmented telescopes.
Yaitskova, Natalia; Dohlen, Kjetil; Dierickx, Philippe
2003-08-01
We present an analysis of the diffraction effects from a segmented aperture with a very large number of segments-prototype of the next generation of extremely large telescopes. This analysis is based on the point-spread-function analytical calculation for Keck-type hexagonal segmentation geometry. We concentrate on the effects that lead to the appearance of speckles and/or a regular pattern of diffraction peaks. These effects are related to random piston and tip-tilt errors on each segment, gaps between segments, and segment edge distortion. We deliver formulas and the typical numerical values for the Strehl ratio, the relative intensity of higher-order diffraction peaks, and the averaged intensity of speckles associated with each particular case of segmentation error.
Coordinated Optimization of Visual Cortical Maps (II) Numerical Studies
Reichl, Lars; Heide, Dominik; Löwel, Siegrid; Crowley, Justin C.; Kaschube, Matthias; Wolf, Fred
2012-01-01
In the juvenile brain, the synaptic architecture of the visual cortex remains in a state of flux for months after the natural onset of vision and the initial emergence of feature selectivity in visual cortical neurons. It is an attractive hypothesis that visual cortical architecture is shaped during this extended period of juvenile plasticity by the coordinated optimization of multiple visual cortical maps such as orientation preference (OP), ocular dominance (OD), spatial frequency, or direction preference. In part (I) of this study we introduced a class of analytically tractable coordinated optimization models and solved representative examples, in which a spatially complex organization of the OP map is induced by interactions between the maps. We found that these solutions near symmetry breaking threshold predict a highly ordered map layout. Here we examine the time course of the convergence towards attractor states and optima of these models. In particular, we determine the timescales on which map optimization takes place and how these timescales can be compared to those of visual cortical development and plasticity. We also assess whether our models exhibit biologically more realistic, spatially irregular solutions at a finite distance from threshold, when the spatial periodicities of the two maps are detuned and when considering more than 2 feature dimensions. We show that, although maps typically undergo substantial rearrangement, no other solutions than pinwheel crystals and stripes dominate in the emerging layouts. Pinwheel crystallization takes place on a rather short timescale and can also occur for detuned wavelengths of different maps. Our numerical results thus support the view that neither minimal energy states nor intermediate transient states of our coordinated optimization models successfully explain the architecture of the visual cortex. We discuss several alternative scenarios that may improve the agreement between model solutions and biological
da Rocha, Leticia; Sloane, Elliot; M Bassani, Jose
2005-01-01
This study describes a framework to support the choice of the maintenance service (in-house or third party contract) for each category of medical equipment based on: a) the real medical equipment maintenance management system currently used by the biomedical engineering group of the public health system of the Universidade Estadual de Campinas located in Brazil to control the medical equipment maintenance service, b) the Activity Based Costing (ABC) method, and c) the Analytic Hierarchy Process (AHP) method. Results show the cost and performance related to each type of maintenance service. Decision-makers can use these results to evaluate possible strategies for the categories of equipment.
da Rocha, Leticia; Sloane, Elliot; M Bassani, Jose
2005-01-01
This study describes a framework to support the choice of the maintenance service (in-house or third party contract) for each category of medical equipment based on: a) the real medical equipment maintenance management system currently used by the biomedical engineering group of the public health system of the Universidade Estadual de Campinas located in Brazil to control the medical equipment maintenance service, b) the Activity Based Costing (ABC) method, and c) the Analytic Hierarchy Process (AHP) method. Results show the cost and performance related to each type of maintenance service. Decision-makers can use these results to evaluate possible strategies for the categories of equipment. PMID:17281912
Zhang, Yichuan; Wang, Jiangping
2015-07-01
Rivers serve as a highly valued component in ecosystem and urban infrastructures. River planning should follow basic principles of maintaining or reconstructing the natural landscape and ecological functions of rivers. Optimization of planning scheme is a prerequisite for successful construction of urban rivers. Therefore, relevant studies on optimization of scheme for natural ecology planning of rivers is crucial. In the present study, four planning schemes for Zhaodingpal River in Xinxiang City, Henan Province were included as the objects for optimization. Fourteen factors that influenced the natural ecology planning of urban rivers were selected from five aspects so as to establish the ANP model. The data processing was done using Super Decisions software. The results showed that important degree of scheme 3 was highest. A scientific, reasonable and accurate evaluation of schemes could be made by ANP method on natural ecology planning of urban rivers. This method could be used to provide references for sustainable development and construction of urban rivers. ANP method is also suitable for optimization of schemes for urban green space planning and design.
Advanced Cogeneration Technology Economic Optimization Study (ACTEOS)
NASA Technical Reports Server (NTRS)
Nanda, P.; Ansu, Y.; Manuel, E. H., Jr.; Price, W. G., Jr.
1980-01-01
The advanced cogeneration technology economic optimization study (ACTEOS) was undertaken to extend the results of the cogeneration technology alternatives study (CTAS). Cost comparisons were made between designs involving advanced cogeneration technologies and designs involving either conventional cogeneration technologies or not involving cogeneration. For the specific equipment cost and fuel price assumptions made, it was found that: (1) coal based cogeneration systems offered appreciable cost savings over the no cogeneration case, while systems using coal derived liquids offered no costs savings; and (2) the advanced cogeneration systems provided somewhat larger cost savings than the conventional systems. Among the issues considered in the study included: (1) temporal variations in steam and electric demands; (2) requirements for reliability/standby capacity; (3) availability of discrete equipment sizes; (4) regional variations in fuel and electricity prices; (5) off design system performance; and (6) separate demand and energy charges for purchased electricity.
Experimental and analytical studies of advanced air cushion landing systems
NASA Technical Reports Server (NTRS)
Lee, E. G. S.; Boghani, A. B.; Captain, K. M.; Rutishauser, H. J.; Farley, H. L.; Fish, R. B.; Jeffcoat, R. L.
1981-01-01
Several concepts are developed for air cushion landing systems (ACLS) which have the potential for improving performance characteristics (roll stiffness, heave damping, and trunk flutter), and reducing fabrication cost and complexity. After an initial screening, the following five concepts were evaluated in detail: damped trunk, filled trunk, compartmented trunk, segmented trunk, and roll feedback control. The evaluation was based on tests performed on scale models. An ACLS dynamic simulation developed earlier is updated so that it can be used to predict the performance of full-scale ACLS incorporating these refinements. The simulation was validated through scale-model tests. A full-scale ACLS based on the segmented trunk concept was fabricated and installed on the NASA ACLS test vehicle, where it is used to support advanced system development. A geometrically-scaled model (one third full scale) of the NASA test vehicle was fabricated and tested. This model, evaluated by means of a series of static and dynamic tests, is used to investigate scaling relationships between reduced and full-scale models. The analytical model developed earlier is applied to simulate both the one third scale and the full scale response.
Applications of nuclear analytical techniques to environmental studies
NASA Astrophysics Data System (ADS)
Freitas, M. C.; Pacheco, A. M. G.; Marques, A. P.; Barros, L. I. C.; Reis, M. A.
2001-07-01
A few examples of application of nuclear-analytical techniques to biological monitors—natives and transplants—are given herein. Parmelia sulcata Taylor transplants were set up in a heavily industrialized area of Portugal—the Setúbal peninsula, about 50 km south of Lisbon—where indigenous lichens are rare. The whole area was 10×15 km around an oil-fired power station, and a 2.5×2.5 km grid was used. In north-western Portugal, native thalli of the same epiphytes (Parmelia spp., mostly Parmelia sulcata Taylor) and bark from olive trees (Olea europaea) were sampled across an area of 50×50 km, using a 10×10 km grid. This area is densely populated and features a blend of rural, urban-industrial and coastal environments, together with the country's second-largest metro area (Porto). All biomonitors have been analyzed by INAA and PIXE. Results were put through nonparametric tests and factor analysis for trend significance and emission sources, respectively.
Heat pipe thermionic reactor shield optimization studies
NASA Astrophysics Data System (ADS)
Keshishan, Vahé; Dix, Terry E.
1992-01-01
Shield optimization studies were conducted for a thermionic reactor, that uses heat pipes for both reactor heat removal and radiator. The radiator was placed on the opposite side of the payload to more efficiency reject the heat without affecting the LiH shadow shield. Neutron scattering off the radiator was an important consideration. The shield that was added to reduce the neutron scattering by itself became a source for scattering. By proper shield material selection, the radiator and radiator shield scattering contribution was reduced. A direct shield material selection trade study was performed, and tungsten was selected for the gamma ray shield. The direct shield mass was then optimized with respect to separation distance, using both the mass of the boom and electrical cables. A very important conclusion was that the optimum system mass depends on the boom structural criteria that is used. At a separation distance of 5 m the shield mass was calculated to be 1,445 kg. At 10 m, the shield mass drops to 700 kg; however, the additional electrical cable mass was 73 kg and the additional boom mass was 335 kg (or 67 kg/m) for a total mass of 1,108 kg. The boom minimum resonant structural frequency was 10 Hz.
Has analytical flexibility increased in imaging studies of bipolar disorder and major depression?
Munafò, M R; Kempton, M J
2015-02-01
There has been extensive discussion of problems of reproducibility of research. Analytical flexibility may contribute to this, by increasing the likelihood that a reported finding represents a chance result. We explored whether analytical flexibility has increased over time, using human imaging studies of bipolar disorder and major depression. Our results indicate that the number of measures collected per study has increased over time for studies of bipolar disorder, but not for studies of major depression.
Experimental and analytical study of a boiling collector in thermal siphon operation
Silva, M. da; Eugenia, M.
1992-01-01
The purpose of this study is to analytically and experimentally evaluate the performance of a boiling solar collector in thermal siphon operation so that, in future work, solar collectors can be optimized for boiling operation. A new procedure, based on boiling heat transfer fundamentals, is developed to estimate the rate of energy gain in the collector. The temperature of the absorber plate is determined from the simultaneous solution of the rate of energy absorbed by the collector and the rate of energy used in boiling as a function of vapor bubble density, the energy required for bubble formation, and the volumetric flow rate through the collector. Since the volumetric flow rate could not be predicted theoretically, experimentally estimated values are used in the numerical calculation. This model is an improvement over previous models which assume that the total mass flow rate that flows through the collector boils, when in reality just a small percent of this mass flow boils and most of it is recirculated. To validate the analytical model, the thermal efficiency and the absorber plate temperature of two collector-condenser systems are experimentally determined. Measurements with both a conventional sheet with tube and a waffled flat plate collector indicate the importance of collector geometry. The two-phase thermal siphon system operates at practically the same thermal efficiency as the hydronic single-phase system, but it uses one less pump, the net rate of useful energy transfer in the two-phase system is higher than in the single-phase system. When boiling collectors are designed for two-phase operation, they may out-perform hydronic collectors.
Li, Zukui; Ding, Ran; Floudas, Christodoulos A.
2011-01-01
Robust counterpart optimization techniques for linear optimization and mixed integer linear optimization problems are studied in this paper. Different uncertainty sets, including those studied in literature (i.e., interval set; combined interval and ellipsoidal set; combined interval and polyhedral set) and new ones (i.e., adjustable box; pure ellipsoidal; pure polyhedral; combined interval, ellipsoidal, and polyhedral set) are studied in this work and their geometric relationship is discussed. For uncertainty in the left hand side, right hand side, and objective function of the optimization problems, robust counterpart optimization formulations induced by those different uncertainty sets are derived. Numerical studies are performed to compare the solutions of the robust counterpart optimization models and applications in refinery production planning and batch process scheduling problem are presented. PMID:21935263
Li, Zukui; Ding, Ran; Floudas, Christodoulos A
2011-09-21
Robust counterpart optimization techniques for linear optimization and mixed integer linear optimization problems are studied in this paper. Different uncertainty sets, including those studied in literature (i.e., interval set; combined interval and ellipsoidal set; combined interval and polyhedral set) and new ones (i.e., adjustable box; pure ellipsoidal; pure polyhedral; combined interval, ellipsoidal, and polyhedral set) are studied in this work and their geometric relationship is discussed. For uncertainty in the left hand side, right hand side, and objective function of the optimization problems, robust counterpart optimization formulations induced by those different uncertainty sets are derived. Numerical studies are performed to compare the solutions of the robust counterpart optimization models and applications in refinery production planning and batch process scheduling problem are presented.
NASA Astrophysics Data System (ADS)
Richard, Luke
The effectiveness of shifting the failure mode away from delamination by the installation of multiple fasteners in series which arrests and stabilizes mixed mode interlaminar failure in composite structures has been demonstrated through analytical and experimental investigation. Based on the novel mixed mode axially loaded specimen, a multi-fastener specimen was manufactured using a quasi-isotropic layup. Testing showed that the damage tolerance of the structure was improved by the inclusion of a second fastener in the crack arrest feature, with laminate failure occurring before significant delamination propagation past the second fastener. Concurrently, finite element models were developed with good agreement of the results. Parametric studies were performed which aid in the optimization of the feature by studying the relative effect of various parameters such as fastener spacing and stiffness as well as laminate thickness and layup. Additional modeling investigated the crack curvature caused by the installation of a fastener, and the possibility of modeling the system with one dimensional elements. It is recommended that the finite element solution be used to aid in the design of alternate specimen configurations which would increase the crack length prior to total laminate failure.
A Spectrophotometric Study of the Permanganate-Oxalate Reaction: An Analytical Laboratory Experiment
ERIC Educational Resources Information Center
Kalbus, Gene E.; Lieu, Van T.; Kalbus, Lee H.
2004-01-01
The spectrophotometric method assists in the study of potassium permanganate-oxalate reaction. Basic analytical techniques and rules are implemented in the experiment, which can also include the examination of other compounds oxidized by permanganate.
Kang, Youn-Ah; Stasko, J
2012-12-01
While the formal evaluation of systems in visual analytics is still relatively uncommon, particularly rare are case studies of prolonged system use by domain analysts working with their own data. Conducting case studies can be challenging, but it can be a particularly effective way to examine whether visual analytics systems are truly helping expert users to accomplish their goals. We studied the use of a visual analytics system for sensemaking tasks on documents by six analysts from a variety of domains. We describe their application of the system along with the benefits, issues, and problems that we uncovered. Findings from the studies identify features that visual analytics systems should emphasize as well as missing capabilities that should be addressed. These findings inform design implications for future systems.
SRC-I naphtha hydrotreating study pilot plant and oxygen analytical studies. Final technical report
Ulowetz, M.A.
1984-01-01
The first part of this study covered second-stage pilot plant hydrotreating using a UOP nickel-molybdenum (-moly) catalyst and first-stage product from earlier pilot plant work as feedstock. Results from this study indicate that the nickel-moly catalyst is less active than the cobalt-moly catalyst used during original studies over the lower end of the temperature range tested (250 to 280/sup 0/C average bed temperature (ABT)), but should produce satisfactory product contaminant levels at the temperature range of commercial interest (335 to 345/sup 0/C ABT). The second part of the study covered oxygen analysis comprising two separate programs. The first was aimed at determining the effect of various molecular sieve drying techniques on SRC-I hydrotreated naphtha. This resulted in the recommendation that 3A molecular sieves be left in contact with the naphtha before analysis to assure that the sample remains relatively dry (approx. 20 wt-ppM water), and therefore minimize water interference during analysis. The second program was conducted to determine if different oxygen concentrations in the range of 10 to 100 wt-ppM. The results showed that scatter in the analytical data was too large to permit conclusions relative to the type of oxygen compound. Further combustion/GC analytical method development is recommended. In general, the results from the oxygen analytical study are very beneficial to the ongoing effort to develop an accurate method for total oxygen analysis in the 10 to 100 wt-ppM range. 3 figures, 12 tables.
Analytical Study on Thermal and Mechanical Design of Printed Circuit Heat Exchanger
Su-Jong Yoon; Piyush Sabharwall; Eung-Soo Kim
2013-09-01
The analytical methodologies for the thermal design, mechanical design and cost estimation of printed circuit heat exchanger are presented in this study. In this study, three flow arrangements of parallel flow, countercurrent flow and crossflow are taken into account. For each flow arrangement, the analytical solution of temperature profile of heat exchanger is introduced. The size and cost of printed circuit heat exchangers for advanced small modular reactors, which employ various coolants such as sodium, molten salts, helium, and water, are also presented.
Analytical study of spacecraft deposition contamination by internal reflection spectroscopy
NASA Technical Reports Server (NTRS)
Mookherji, T.
1972-01-01
Infrared absorption spectra of ten individual contaminant materials and four binary mixtures of these have been studied using the internal reflection spectroscopy technique. The effect of ultraviolet radiation on these contaminants has also been studied. It has been observed that all siloxanes, silanes, and esters are drastically affected by ultraviolet irradiation. In most cases polymerization and tar formation results.
A Factor Analytic Study of the Internet Usage Scale
ERIC Educational Resources Information Center
Monetti, David M.; Whatley, Mark A.; Hinkle, Kerry T.; Cunningham, Kerry T.; Breneiser, Jennifer E.; Kisling, Rhea
2011-01-01
This study developed an Internet Usage Scale (IUS) for use with adolescent populations. The IUS is a 26-item scale that measures participants' beliefs about how their Internet usage impacts their behavior. The sample for this study consisted of 947 middle school students. An exploratory factor analysis with varimax rotation was conducted on the…
A Factor Analytic Study of the Teaching Events Stress Inventory.
ERIC Educational Resources Information Center
Alexander, Livingston; And Others
The purpose of this study was to determine if definitive factors emerge from the responses of teachers to the Teaching Events Stress Inventory (TESI). In a series of three studies during the years 1980 to 1982, data were collected to assess the levels and sources of stress experienced by 660 teachers in central and western Kentucky. The subjects…
An analytic modeling and system identification study of rotor/fuselage dynamics at hover
NASA Technical Reports Server (NTRS)
Hong, Steven W.; Curtiss, H. C., Jr.
1993-01-01
A combination of analytic modeling and system identification methods have been used to develop an improved dynamic model describing the response of articulated rotor helicopters to control inputs. A high-order linearized model of coupled rotor/body dynamics including flap and lag degrees of freedom and inflow dynamics with literal coefficients is compared to flight test data from single rotor helicopters in the near hover trim condition. The identification problem was formulated using the maximum likelihood function in the time domain. The dynamic model with literal coefficients was used to generate the model states, and the model was parametrized in terms of physical constants of the aircraft rather than the stability derivatives, resulting in a significant reduction in the number of quantities to be identified. The likelihood function was optimized using the genetic algorithm approach. This method proved highly effective in producing an estimated model from flight test data which included coupled fuselage/rotor dynamics. Using this approach it has been shown that blade flexibility is a significant contributing factor to the discrepancies between theory and experiment shown in previous studies. Addition of flexible modes, properly incorporating the constraint due to the lag dampers, results in excellent agreement between flight test and theory, especially in the high frequency range.
An analytic modeling and system identification study of rotor/fuselage dynamics at hover
NASA Technical Reports Server (NTRS)
Hong, Steven W.; Curtiss, H. C., Jr.
1993-01-01
A combination of analytic modeling and system identification methods have been used to develop an improved dynamic model describing the response of articulated rotor helicopters to control inputs. A high-order linearized model of coupled rotor/body dynamics including flap and lag degrees of freedom and inflow dynamics with literal coefficients is compared to flight test data from single rotor helicopters in the near hover trim condition. The identification problem was formulated using the maximum likelihood function in the time domain. The dynamic model with literal coefficients was used to generate the model states, and the model was parametrized in terms of physical constants of the aircraft rather than the stability derivatives resulting in a significant reduction in the number of quantities to be identified. The likelihood function was optimized using the genetic algorithm approach. This method proved highly effective in producing an estimated model from flight test data which included coupled fuselage/rotor dynamics. Using this approach it has been shown that blade flexibility is a significant contributing factor to the discrepancies between theory and experiment shown in previous studies. Addition of flexible modes, properly incorporating the constraint due to the lag dampers, results in excellent agreement between flight test and theory, especially in the high frequency range.
Experimental and Analytical Studies of Solar System Chemistry
NASA Technical Reports Server (NTRS)
Burnett, Donald S.
2003-01-01
The cosmochemistry research funded by this grant resulted in the publications given in the attached Publication List. The research focused in three areas: (1) Experimental studies of trace element partitioning. (2) Studies of the minor element chemistry and O isotopic compositions of MgAlO4 spinels from Ca-Al-Rich Inclusions in carbonaceous chondrite meteorites, and (3) The abundances and chemical fractionations of Th and U in chondritic meteorites.
Asynchronous telehealth: a scoping review of analytic studies
Deshpande, Amol; Khoja, Shariq; Lorca, Julio; McKibbon, Ann; Rizo, Carlos; Husereau, Donald; Jadad, Alejandro R
2009-01-01
Background Asynchronous telehealth captures clinically important digital samples (e.g., still images, video, audio, text files) and relevant data in one location and subsequently transmits these files for interpretation at a remote site by health professionals without requiring the simultaneous presence of the patient involved and his or her health care provider. Its utility in the health care system, however, still remains poorly defined. We conducted this scoping review to determine the impact of asynchronous telehealth on health outcomes, process of care, access to health services, and health resources. Methods A search was performed up to December 2006 of MEDLINE, CINAHL, HealthSTAR, the Database of Abstracts of Reviews of Effectiveness, and The Cochrane Library. Studies were included if they contained original data on the use of asynchronous telehealth and were published in English in a peer-reviewed journal. Two independent reviewers screened all articles and extracted data, reaching consensus on the articles and data identified. Data were extracted on general study characteristics, clinical domain, technology, setting, category of outcome, and results. Study quality (internal validity) was assessed using the Jadad scale for randomized controlled trials and the Downs and Black index for non-randomized studies. Summary data were categorized by medical specialty and presented qualitatively. Results The scoping review included 52 original studies from 238 citations identified; of these 52, almost half focused on the use of telehealth in dermatology. Included studies were characterized by diverse designs, interventions, and outcomes. Only 16 studies were judged to be of high quality. Most studies showed beneficial effects in terms of diagnostic accuracy, wait times, referral management, and satisfaction with services. Evidence on the impact of asynchronous telehealth on resource use in dermatology suggests a reduction in the number of, or avoidance of, in
Behavior analytic studies of creativity: A critical review.
Winston, A S; Baker, J E
1985-01-01
Studies that treat creativity as operant behavior were critically reviewed. Of the twenty studies, most met minimal requirements for methodological adequacy; all provided at least some evidence for increased creative responding. Major difficulties involved potential confounds between instructions and contingencies, lack of an independent record of the training interaction, lack of social validation data, and very limited evidence for generalization. Several issues were discussed: problems in the behavioral definition of creativity, objections to the use of contingent reinforcement, and the need for empirical analysis of the creative process.
A clinical research analytics toolkit for cohort study.
Yu, Yiqin; Zhu, Yu; Sun, Xingzhi; Tao, Ying; Zhang, Shuo; Xu, Linhao; Pan, Yue
2012-01-01
This paper presents a clinical informatics toolkit that can assist physicians to conduct cohort studies effectively and efficiently. The toolkit has three key features: 1) support of procedures defined in epidemiology, 2) recommendation of statistical methods in data analysis, and 3) automatic generation of research reports. On one hand, our system can help physicians control research quality by leveraging the integrated knowledge of epidemiology and medical statistics; on the other hand, it can improve productivity by reducing the complexities for physicians during their cohort studies.
Analytical study of nozzle performance for nuclear thermal rockets
NASA Technical Reports Server (NTRS)
Davidian, Kenneth O.; Kacynski, Kenneth J.
1991-01-01
A parametric study has been conducted by the NASA-Lewis Rocket Engine Design Expert System for the convergent-divergent nozzle of the Nuclear Thermal Rocket system, which uses a nuclear reactor to heat hydrogen to high temperature and then expands it through the nozzle. It is established by the study that finite-rate chemical reactions lower performance levels from theoretical levels. Major parametric roles are played by chamber temperature and chamber pressure. A maximum performance of 930 sec is projected at 2700 K, and of 1030 at 3100 K.
Optimality study of a gust alleviation system for light wing-loading STOL aircraft
NASA Technical Reports Server (NTRS)
Komoda, M.
1976-01-01
An analytical study was made of an optimal gust alleviation system that employs a vertical gust sensor mounted forward of an aircraft's center of gravity. Frequency domain optimization techniques were employed to synthesize the optimal filters that process the corrective signals to the flaps and elevator actuators. Special attention was given to evaluating the effectiveness of lead time, that is, the time by which relative wind sensor information should lead the actual encounter of the gust. The resulting filter is expressed as an implicit function of the prescribed control cost. A numerical example for a light wing loading STOL aircraft is included in which the optimal trade-off between performance and control cost is systematically studied.
Fears of a Heterogeneous, Nonpsychiatric Sample: A Factor Analytic Study.
ERIC Educational Resources Information Center
Kirkpatrick, Dwight R.; Berg, Alan J.
Previous studies on common fears have been vague and have not met requirements for using factor analysis. To avoid some of these problems, a broader age range and a separate analysis of males and females were designed for a sample of 545 individuals, ages 15-89, who responded to 133 fear-scale items. "Death of a loved one" was the greatest fear…
Analytical studies of new airfoils for wind turbines
NASA Technical Reports Server (NTRS)
Wentz, W. H., Jr.; Calhoun, J. T.
1981-01-01
Computer studies were conducted to analyze the potential gains associated with utilizing new airfoils for large wind turbine rotor blades. Attempts to include 3-dimensional stalling effects were inconclusive. It is recommended that blade pressure measurements be made to clarify the nature of blade stalling. It is also recommended that new laminar flow airfoils be used as rotor blade sections.
Children's Content Interest--A Factor Analytic Study.
ERIC Educational Resources Information Center
Feeley, Joan T.
Recognizing that interest is essential to motivation, this study was designed both to identify and describe the content interest patterns and media preferences (print and television) of middle-grade children and to determine any relationship between these interests and sex, race, or socioeconomic status (SES). An inventory was administered to 250…
Assessing Vocal Performances Using Analytical Assessment: A Case Study
ERIC Educational Resources Information Center
Gynnild, Vidar
2016-01-01
This study investigated ways to improve the appraisal of vocal performances within a national academy of music. Since a criterion-based assessment framework had already been adopted, the conceptual foundation of an assessment rubric was used as a guide in an action research project. The group of teachers involved wanted to explore thinking…
Sex Differences in Helping Behavior: A Meta-Analytic Study.
ERIC Educational Resources Information Center
Renner, Patricia; Eagly, Alice H.
Whether or not there are sex differences in helping behavior is a question that has attracted interest from both theoretical and applied perspectives. A meta-analysis was conducted of 172 studies of helping behavior, coded for publication date, source, sex of author, sample size, setting, type of appeal for help, availability of other helpers, sex…
A Study of Online Exams Procrastination Using Data Analytics Techniques
ERIC Educational Resources Information Center
Levy, Yair; Ramim, Michelle M.
2012-01-01
Procrastination appears to be an inevitable part of daily life, especially for activities that are bounded by deadlines. It has implications for performance and is known to be linked to poor personal time management. Although research related to procrastination as a general behavior has been well established, studies assessing procrastination in…
Analytical, Experimental, and Modelling Studies of Lunar and Terrestrial Rocks
NASA Technical Reports Server (NTRS)
Haskin, Larry A.
1997-01-01
The goal of our research has been to understand the paths and the processes of planetary evolution that produced planetary surface materials as we find them. Most of our work has been on lunar materials and processes. We have done studies that obtain geological knowledge from detailed examination of regolith materials and we have reported implications for future sample-collecting and on-surface robotic sensing missions. Our approach has been to study a suite of materials that we have chosen in order to answer specific geologic questions. We continue this work under NAG5-4172. The foundation of our work has been the study of materials with precise chemical and petrographic analyses, emphasizing analysis for trace chemical elements. We have used quantitative models as tests to account for the chemical compositions and mineralogical properties of the materials in terms of regolith processes and igneous processes. We have done experiments as needed to provide values for geochemical parameters used in the models. Our models take explicitly into account the physical as well as the chemical processes that produced or modified the materials. Our approach to planetary geoscience owes much to our experience in terrestrial geoscience, where samples can be collected in field context and sampling sites revisited if necessary. Through studies of terrestrial analog materials, we have tested our ideas about the origins of lunar materials. We have been mainly concerned with the materials of the lunar highland regolith, their properties, their modes of origin, their provenance, and how to extrapolate from their characteristics to learn about the origin and evolution of the Moon's early igneous crust. From this work a modified model for the Moon's structure and evolution is emerging, one of globally asymmetric differentiation of the crust and mantle to produce a crust consisting mainly of ferroan and magnesian igneous rocks containing on average 70-80% plagioclase, with a large
Pharmacognostical and analytical study of Tulsi-Amla-Yasti Ghrita.
Datta, Debdas; Chandola, Harimohan; Agarwal, S K; Shukla, Vinay J; Pandya, Preeti N
2012-04-01
Tulasi Amla Yashti Ghrita is an Ayurvedic formulation, which is beneficial in the management of the side effects of Head and Neck Malignancies induced by Radiotherapy and Chemotherapy. A pharmacognostical study involving both the macroscopic and powder microscopy of raw drugs of Tulasi Amla Yashti Ghrita and a physicochemical analysis of the finished product were carried out, to evaluate the quality of the formulation. The specific gravity of the formulation was 0.9130 and pH was 3.5. Thin layer chromatography (TLC) and high performance thin layer chromatography (HPTLC) were carried out after organizing the appropriate solvent system, in which five spots were distinguished in TLC and nine spots in HPTLC. Most of the Rf values for the spots observed were identical. The observations could be considered to be the reference standards in future studies. PMID:23559803
Data Analytics Under Deployed Conditions: A Case Study.
Mellott, Mark D; Bonica, Mark J; Mapes, Matthew J
2015-01-01
Like their colleagues in fixed facilities, healthcare planners operating in a combat environment face the problem of transforming data into actionable information. Not all data is useful for decision-making and not all data comes neatly packaged. In this case study, the authors present an effort to collect and analyze data about forward surgical team utilization. The article shares the variety of data collected and the process of analysis, and concludes with a recommended process for data analysis in the field.
An analytical study for the design of advanced rotor airfoils
NASA Technical Reports Server (NTRS)
Kemp, L. D.
1973-01-01
A theoretical study has been conducted to design and evaluate two airfoils for helicopter rotors. The best basic shape, designed with a transonic hodograph design method, was modified to meet subsonic criteria. One airfoil had an additional constraint for low pitching-moment at the transonic design point. Airfoil characteristics were predicted. Results of a comparative analysis of helicopter performance indicate that the new airfoils will produce reduced rotor power requirements compared to the NACA 0012. The hodograph design method, written in CDC Algol, is listed and described.
Noise characteristics of upper surface blown configurations: Analytical Studies
NASA Technical Reports Server (NTRS)
Reddy, N. N.; Tibbetts, J. G.; Pennock, A. P.; Tam, C. K. W.
1978-01-01
Noise and flow results of upper surface blown configurations were analyzed. The dominant noise source mechanisms were identified from experimental data. From far-field noise data for various geometric and operational parameters, an empirical noise prediction program was developed and evaluated by comparing predicted results with experimental data from other tests. USB aircraft compatibility studies were conducted using the described noise prediction and a cruise performance data base. A final design aircraft was selected and theory was developed for the noise from the trailing edge wake assuming it as a highly sheared layer.
Experimental and Analytic Studies of an RF Load Resistor
Borovina, D.L.; Humphries, S.; Gahl, J.M.; Rees, D.
1999-03-29
The pulsed output of an 850-MHz klystron was directed into a load assembly containing a water-cooled, 50-ohm resistor. The load was systematically subjected to high peak-power pulses from the klystron. Several thin-film resistors were tested and exhibited various damage patterns for different combinations of peak microwave power (33 kW - 500 kW) and heat input. In order to better understand the phenomena observed, the electromagnetic field distribution inside the resistor housing was studied with WaveSim, a two-dimensional, finite-element scattering code. The conformal mesh of the program allowed accurate representations of the complex assembly geometry.
Data Analytics Under Deployed Conditions: A Case Study.
Mellott, Mark D; Bonica, Mark J; Mapes, Matthew J
2015-01-01
Like their colleagues in fixed facilities, healthcare planners operating in a combat environment face the problem of transforming data into actionable information. Not all data is useful for decision-making and not all data comes neatly packaged. In this case study, the authors present an effort to collect and analyze data about forward surgical team utilization. The article shares the variety of data collected and the process of analysis, and concludes with a recommended process for data analysis in the field. PMID:26606410
Experimental and Analytical Studies for a Computational Materials Program
NASA Technical Reports Server (NTRS)
Knauss, W. G.
1999-01-01
The studies supported by Grant NAG1-1780 were directed at providing physical data on polymer behavior that would form the basis for computationally modeling these types of materials. Because of ongoing work in polymer characterization this grant supported part of a larger picture in this regard. Efforts went into two combined areas of their time dependent mechanical response characteristics: Creep properties on the one hand, subject to different volumetric changes (nonlinearly viscoelastic behavior) and time or frequency dependence of dilatational material behavior. The details of these endeavors are outlined sufficiently in the two appended publications, so that no further description of the effort is necessary.
Discourse analytic study of counseling sessions in stroke physiotherapy.
Talvitie, Ulla; Pyöriä, Outi
2006-01-01
Studies on the interaction between physiotherapists and patients during treatment sessions have found low levels of communicative participation by patients and lack of direct influence by patients on the content of their treatment. This article reports the results of 7 counseling sessions in which physiotherapists and patients with stroke and their caregivers discussed the patients' postural control and balance, which had been tested and videotaped at different stages of the rehabilitation process. The physiotherapists' discourses relating to the videotaped test performances were either brief comments on the patient's performance or critical appraisals with references to difficulties encountered during performance. Performances of the easier tasks were treated by the physiotherapists with rhetorical questions. The second type of discourse consisted of the physiotherapists directing the patients' attention to their problems, and of the patients' and caregivers' initiatives leading to conversation about the patients' problems. The patients understood the significance of the test performance for their life at home in varying ways. The results of this study showed that successful counseling calls for physiotherapists to develop dialogic communication skills to help patients in coconstructing their home exercise together with their social network.
Microstructural studies of dental amalgams using analytical transmission electron microscopy
NASA Astrophysics Data System (ADS)
Hooghan, Tejpal Kaur
Dental amalgams have been used for centuries as major restorative materials for decaying teeth. Amalgams are prepared by mixing alloy particles which contain Ag, Sn, and Cu as the major constituent elements with liquid Hg. The study of microstructure is essential in understanding the setting reactions and improving the properties of amalgams. Until the work reported in this dissertation, optical microscopy (OM), scanning electron microscopy (SEM), and x-ray diffractometry (XRD) were used commonly to analyze amalgam microstructures. No previous systematic transmission electron microscopy (TEM) study has been performed due to sample preparation difficulties and composite structure of dental amalgams. The goal of this research was to carry out detailed microstructural and compositional studies of dental amalgams. This was accomplished using the enhanced spatial resolution of the TEM and its associated microanalytical techniques, namely, scanning transmission electron microscopy (STEM), x-ray energy dispersive spectroscopy (XEDS) and micro-microdiffraction (mumuD). A new method was developed for thinning amalgam samples to electron transparency using the "wedge technique." Velvalloy, a low-Cu amalgam, and Tytin, a high-Cu amalgam, were the two amalgams characterized. Velvalloy is composed of a Agsb2Hgsb3\\ (gammasb1)/HgSnsb{7-9}\\ (gammasb2) matrix surrounding unreacted Agsb3Sn (gamma) particles. In addition, hitherto uncharacterized reaction layers between Agsb3Sn(gamma)/Agsb2Hgsb3\\ (gammasb2)\\ and\\ Agsb2Hgsb3\\ (gammasb1)/HgSnsb{7-9}\\ (gammasb2) were observed and analyzed. An Ag-Hg-Sn (betasb1) phase was clearly identified for the first time. In Tytin, the matrix consists of Agsb2Hgsb3\\ (gammasb1) grains. Fine precipitates of Cusb6Snsb5\\ (etasp') are embedded inside the gammasb1 and at the grain boundaries. These precipitates are responsible for the improved creep resistance of Tytin compared to Velvalloy. The additional Cu has completely eliminated the gammasb
An analytical study of reduced-gravity flow dynamics
NASA Technical Reports Server (NTRS)
Bradshaw, R. D.; Kramer, J. L.; Zich, J. L.
1976-01-01
Addition of surface tension forces to a marker-and-cell code and the performance of four incompressible fluid simulations in reduced gravity, were studied. This marker-and-cell code has a variable grid capability with arbitrary curved boundaries and time dependent acceleration fields. The surface tension logic includes a spline fit of surface marker particles as well as contact angle logic for straight and curved wall boundaries. Three types of flow motion were simulated with the improved code: impulsive settling in a model Centaur LH2 tank, continuous settling in a model and full scale Centaur LO2 tank and mixing in a Centaur LH2 tank. The impulsive settling case confirmed a drop tower analysis which indicated more orderly fluid collection flow patterns with this method providing a potential savings in settling propellants. In the LO2 tank, fluid collection and flow simulation into the thrust barrel were achieved. The mixing simulation produced good results indicating both the development of the flow field and fluid interface behavior.
Experimental and analytical studies of a true airspeed sensor
NASA Technical Reports Server (NTRS)
Goglia, G. L.; Shen, J. Y.
1983-01-01
A true airspeed sensor based on the precession of a vortex whistle for sensing airspeeds up to 321.9 km/hr (200 mph). In an attempt to model the complicated fluid mechanics of the vortex precession, three dimensional, inviscid, unsteady, incompressible fluid flow was studied by using the hydrodynamical linearized stability theory. The temporal stability approach was used to derive the relationship between the true airspeed and frequency response. The results show that the frequency response is linearly proportional to the airspeed. A computer program was developed to obtain the numerical solution. Computational results for various parameters were obtained. The designed sensor basically consisted of a vortex tube, a swirler, and a transducer system. A microphone converted the audible tone to an electronic frequency signal. Measurements for both the closed conduit tests and wind tunnel tests were recorded. For a specific flow rate or airspeed, larger exit swirler angles produced higher frequencies. For a smaller cross sectional area in the precessional flow region, the frequency was higher. It was observed that as the airspeed was increased the Strouhal number remained constant.
An Analytical Study for Subsonic Oblique Wing Transport Concept
NASA Technical Reports Server (NTRS)
Bradley, E. S.; Honrath, J.; Tomlin, K. H.; Swift, G.; Shumpert, P.; Warnock, W.
1976-01-01
The oblique wing concept has been investigated for subsonic transport application for a cruise Mach number of 0.95. Three different mission applications were considered and the concept analyzed against the selected mission requirements. Configuration studies determined the best area of applicability to be a commercial passenger transport mission. The critical parameter for the oblique wing concept was found to be aspect ratio which was limited to a value of 6.0 due to aeroelastic divergence. Comparison of the concept final configuration was made with fixed winged configurations designed to cruise at Mach 0.85 and 0.95. The crossover Mach number for the oblique wing concept was found to be Mach 0.91 for takeoff gross weight and direct operating cost. Benefits include reduced takeoff distance, installed thrust and mission block fuel and improved community noise characteristics. The variable geometry feature enables the final configuration to increase range by 10% at Mach 0.712 and to increase endurance by as much as 44%.
Analytical study of nozzle performance for nuclear thermal rockets
NASA Technical Reports Server (NTRS)
Davidian, Kenneth O.; Kacynski, Kenneth J.
1991-01-01
Nuclear propulsion has been identified as one of the key technologies needed for human exploration of the Moon and Mars. The Nuclear Thermal Rocket (NTR) uses a nuclear reactor to heat hydrogen to a high temperature followed by expansion through a conventional convergent-divergent nozzle. A parametric study of NTR nozzles was performed using the Rocket Engine Design Expert System (REDES) at the NASA Lewis Research Center. The REDES used the JANNAF standard rigorous methodology to determine nozzle performance over a range of chamber temperatures, chamber pressures, thrust levels, and different nozzle configurations. A design condition was set by fixing the propulsion system exit radius at five meters and throat radius was varied to achieve a target thrust level. An adiabatic wall was assumed for the nozzle, and its length was assumed to be 80 percent of a 15 degree cone. The results conclude that although the performance of the NTR, based on infinite reaction rates, looks promising at low chamber pressures, finite rate chemical reactions will cause the actual performance to be considerably lower. Parameters which have a major influence on the delivered specific impulse value include the chamber temperature and the chamber pressures in the high thrust domain. Other parameters, such as 2-D and boundary layer effects, kinetic rates, and number of nozzles, affect the deliverable performance of an NTR nozzle to a lesser degree. For a single nozzle, maximum performance of 930 seconds and 1030 seconds occur at chamber temperatures of 2700 and 3100 K, respectively.
Nationwide Multicenter Reference Interval Study for 28 Common Biochemical Analytes in China
Xia, Liangyu; Chen, Ming; Liu, Min; Tao, Zhihua; Li, Shijun; Wang, Liang; Cheng, Xinqi; Qin, Xuzhen; Han, Jianhua; Li, Pengchang; Hou, Li’an; Yu, Songlin; Ichihara, Kiyoshi; Qiu, Ling
2016-01-01
Abstract A nationwide multicenter study was conducted in the China to explore sources of variation of reference values and establish reference intervals for 28 common biochemical analytes, as a part of the International Federation of Clinical Chemistry and Laboratory Medicine, Committee on Reference Intervals and Decision Limits (IFCC/C-RIDL) global study on reference values. A total of 3148 apparently healthy volunteers were recruited in 6 cities covering a wide area in China. Blood samples were tested in 2 central laboratories using Beckman Coulter AU5800 chemistry analyzers. Certified reference materials and value-assigned serum panel were used for standardization of test results. Multiple regression analysis was performed to explore sources of variation. Need for partition of reference intervals was evaluated based on 3-level nested ANOVA. After secondary exclusion using the latent abnormal values exclusion method, reference intervals were derived by a parametric method using the modified Box–Cox formula. Test results of 20 analytes were made traceable to reference measurement procedures. By the ANOVA, significant sex-related and age-related differences were observed in 12 and 12 analytes, respectively. A small regional difference was observed in the results for albumin, glucose, and sodium. Multiple regression analysis revealed BMI-related changes in results of 9 analytes for man and 6 for woman. Reference intervals of 28 analytes were computed with 17 analytes partitioned by sex and/or age. In conclusion, reference intervals of 28 common chemistry analytes applicable to Chinese Han population were established by use of the latest methodology. Reference intervals of 20 analytes traceable to reference measurement procedures can be used as common reference intervals, whereas others can be used as the assay system-specific reference intervals in China. PMID:26945390
NASA Technical Reports Server (NTRS)
Rybak, S. C.
1976-01-01
The performance capabilities and limitations of the instrument pointing system (IPS) are described. Suggestions of design modifications that result in overall improved IPS performance are included. Since the design and configuration of the IPS was modified a portion of the study was performed with the inside-out Gimbal configuration which was updated to the present coincident Gimbal system configuration. Due to the similarity of the two systems, the results obtained for the inside-out Gimbal also apply to the coincident Gimbal system.
Optical microscopy as a comparative analytical technique for single-particle dissolution studies.
Svanbäck, Sami; Ehlers, Henrik; Yliruusi, Jouko
2014-07-20
Novel, simple and cost effective methods are needed to replace advanced chemical analytical techniques, in small-scale dissolution studies. Optical microscopy of individual particles could provide such a method. The aim of the present work was to investigate and verify the applicability of optical microscopy as an analytical technique for drug dissolution studies. The evaluation was performed by comparing image and chemical analysis data of individual dissolving particles. It was shown that the data obtained by image analysis and UV-spectrophotometry produced practically identical dissolution curves, with average similarity and difference factors above 82 and below 4, respectively. The relative standard deviation for image analysis data, of the studied particle size range, varied between 1.9% and 3.8%. Consequently, it is proposed that image analysis can be used, on its own, as a viable analytical technique in single-particle dissolution studies. The possibility for significant reductions in sample preparation, operational cost, time and substance consumption gives optical detection a clear advantage over chemical analytical methods. Thus, image analysis could be an ideal and universal analytical technique for rapid small-scale dissolution studies.
Publication Bias in Studies of an Applied Behavior-Analytic Intervention: An Initial Analysis
ERIC Educational Resources Information Center
Sham, Elyssa; Smith, Tristram
2014-01-01
Publication bias arises when studies with favorable results are more likely to be reported than are studies with null findings. If this bias occurs in studies with single-subject experimental designs (SSEDs) on applied behavior-analytic (ABA) interventions, it could lead to exaggerated estimates of intervention effects. Therefore, we conducted an…
Perspectives on Using Video Recordings in Conversation Analytical Studies on Learning in Interaction
ERIC Educational Resources Information Center
Rusk, Fredrik; Pörn, Michaela; Sahlström, Fritjof; Slotte-Lüttge, Anna
2015-01-01
Video is currently used in many studies to document the interaction in conversation analytical (CA) studies on learning. The discussion on the method used in these studies has primarily focused on the analysis or the data construction, whereas the relation between data construction and analysis is rarely brought to attention. The aim of this…
NASA Astrophysics Data System (ADS)
Wang, Wen-Shuo; He, Da-Wei; Wang, Ji-Hong; Duan, Jia-Hua; Peng, Hong-Shang; Wu, Hong-Peng; Fu, Ming; Wang, Yong-Sheng; Zhang, Xi-Qing
2014-04-01
The chemiluminescence (CL) performance of luminol is improved using reduced graphene oxide/gold nanoparticle (rGO-AuNP) nano-composites as catalyst. To prepare this catalyst, we propose a linker free, one-step method to in-situ synthesize rGO-AuNP nano-composites. Various measurements are utilized to characterize the resulting rGO-AuNP samples, and it is revealed that rGO could improve the stability and conductivity. Furthermore, we investigate the CL signals of luminal catalyzed by rGO-AuNP. Afterwards, the size effect of particle and the assisted enhancement effect of rGO are studied and discussed in detail. Based on the discussion, an optimal, sensitive and stable rGO-AuNP-luminon-H2O2 CL system is proposed. Finally, we utilize the system as a sensor to detect hydrogen peroxide and organic compounds containing amino, hydroxyl, or thiol groups. The CL system might provide a more attractive platform for various analytical devices with CL detection in the field of biosensors, bioassays, and immunosensors.
An analytical and experimental study of crack extension in center-notched composites
NASA Technical Reports Server (NTRS)
Beuth, Jack L., Jr.; Herakovich, Carl T.
1987-01-01
The normal stress ratio theory for crack extension in anisotropic materials is studied analytically and experimentally. The theory is applied within a microscopic-level analysis of a single center notch of arbitrary orientation in a unidirectional composite material. The bulk of the analytical work of this study applies an elasticity solution for an infinite plate with a center line to obtain critical stress and crack growth direction predictions. An elasticity solution for an infinite plate with a center elliptical flaw is also used to obtain qualitative predictions of the location of crack initiation on the border of a rounded notch tip. The analytical portion of the study includes the formulation of a new crack growth theory that includes local shear stress. Normal stress ratio theory predictions are obtained for notched unidirectional tensile coupons and unidirectional Iosipescu shear specimens. These predictions are subsequently compared to experimental results.
Optimizing Classroom Acoustics Using Computer Model Studies.
ERIC Educational Resources Information Center
Reich, Rebecca; Bradley, John
1998-01-01
Investigates conditions relating to the maximum useful-to-detrimental sound ratios present in classrooms and determining the optimum conditions for speech intelligibility. Reveals that speech intelligibility is more strongly influenced by ambient noise levels and that the optimal location for sound absorbing material is on a classroom's upper…
A Monte-Carlo Study of Confirmatory Factor Analytic Tests of Measurement Equivalence/Invariance
ERIC Educational Resources Information Center
Meade, Adam W.; Lautenschlager, Gary J.
2004-01-01
In recent years, confirmatory factor analytic (CFA) techniques have become the most common method of testing for measurement equivalence/invariance (ME/I). However, no study has simulated data with known differences to determine how well these CFA techniques perform. This study utilizes data with a variety of known simulated differences in factor…
The Effect of Brain Based Learning on Academic Achievement: A Meta-Analytical Study
ERIC Educational Resources Information Center
Gozuyesil, Eda; Dikici, Ayhan
2014-01-01
This study's aim is to measure the effect sizes of the quantitative studies that examined the effectiveness of brain-based learning on students' academic achievement and to examine with the meta-analytical method if there is a significant difference in effect in terms of the factors of education level, subject matter, sampling size, and…
Analytical Study of High Concentration PCB Paint at the Heavy Water Components Test Reactor
Lowry, N.J.
1998-10-21
This report provides results of an analytical study of high concentration PCB paint in a shutdown nuclear test reactor located at the US Department of Energy's Savannah River Site (SRS). The study was designed to obtain data relevant for an evaluation of potential hazards associated with the use of and exposure to such paints.
Does Marriage and Relationship Education Work? A Meta-Analytic Study
ERIC Educational Resources Information Center
Hawkins, Alan J.; Blanchard, Victoria L.; Baldwin, Scott A.; Fawcett, Elizabeth B.
2008-01-01
In this meta-analytic study, the authors examined the efficacy of marriage and relationship education (MRE) on 2 common outcomes: relationship quality and communication skills. A thorough search produced 86 codable reports that yielded 117 studies and more than 500 effect sizes. The effect sizes for relationship quality for experimental studies…
Duerr, Fabian; Benítez, Pablo; Miñano, Juan C; Meuret, Youri; Thienpont, Hugo
2012-02-27
In this work, a new two-dimensional optics design method is proposed that enables the coupling of three ray sets with two lens surfaces. The method is especially important for optical systems designed for wide field of view and with clearly separated optical surfaces. Fermat's principle is used to deduce a set of functional differential equations fully describing the entire optical system. The presented general analytic solution makes it possible to calculate the lens profiles. Ray tracing results for calculated 15th order Taylor polynomials describing the lens profiles demonstrate excellent imaging performance and the versatility of this new analytic design method. PMID:22418364
Liew, Kai Bin; Peh, Kok Khiang; Fung Tan, Yvonne Tze
2013-09-01
An easy, fast and validated RV-HPLC method was invented to quantify donepezil hydrochloride in drug solution and orally disintegrating tablet. The separation was carried out using reversed phase C-18 column (Agilent Eclipse Plus C-18) with UV detection at 268 nm. Method optimization was tested using various composition of organic solvent. The mobile phase comprised of phosphate buffer (0.01M), methanol and acetonitrile (50:30:20, v/v) adjusted to pH 2.7 with phosphoric acid (80%) was found as the optimum mobile phase. The method showed intraday precision and accuracy in the range of 0.24% to -1.83% and -1.83% to 1.99% respectively, while interday precision and accuracy ranged between 1.41% to 1.81% and 0.11% to 1.90% respectively. The standard calibration curve was linear from 0.125 μg/mL to 16 μg/mL, with correlation coefficient of 0.9997±0.00016. The drug solution was stable under room temperature at least for 6 hours. System suitability studies were done. The average plate count was > 2000, tailing factor <1, and capacity factor of 3.30. The retention time was 5.6 min. The HPLC method was used to assay donepezil hydrochloride in tablet and dissolution study of in-house manufactured donepezil orally disintegrating tablet and original Aricept.
Montaser, A.; Huse, G.R.; Wax, R.A.; Chan, S.-K.; Golightly, D.W.; Kane, J.S.; Dorrzapf, A.F.
1984-01-01
An inductively coupled Ar plasma (ICP), generated in a lowflow torch, was investigated by the simplex optimization technique for simultaneous, multielement, atomic emission spectrometry (AES). The variables studied included forward power, observation height, gas flow (outer, intermediate, and nebulizer carrier) and sample uptake rate. When the ICP was operated at 720-W forward power with a total gas flow of 5 L/min, the signal-to-background ratios (S/B) of spectral lines from 20 elements were either comparable or inferior, by a factor ranging from 1.5 to 2, to the results obtained from a conventional Ar ICP. Matrix effect studies on the Ca-PO4 system revealed that the plasma generated in the low-flow torch was as free of vaporizatton-atomizatton interferences as the conventional ICP, but easily ionizable elements produced a greater level of suppression or enhancement effects which could be reduced at higher forward powers. Electron number densities, as determined via the series until line merging technique, were tower ht the plasma sustained in the low-flow torch as compared with the conventional ICP. ?? 1984 American Chemical Society.
Klampfl, Christian W; Leitner, Tanja; Hilder, Emily F
2002-08-01
Microemulsion electrokinetic chromatography (MEEKC) has been applied to the separation of some UV filters (Eusolex 4360, Eusolex 6300, Eusolex OCR, Eusolex 2292, Eusolex 6007, Eusolex 9020, Eusolex HMS, Eusolex OS, and Eusolex 232) commonly found in suntan lotions. The composition of the microemulsion employed was optimized with respect to the best possible separation of the selected analytes using artificial neural networks (ANNs). Two parameters namely the composition of the mixed surfactant system comprising the anionic sodium dodecyl sulfate (SDS) and neutral Brij 35 and the amount of organic modifier (2-propanol) present in the aqueous phase of the microemulsion were modeled. Using an optimized MEEKC buffer consisting of 2.25 g SDS, 0.75 g Brij 35, 6.6 g 1-butanol, 0.8 g n-octane, 17.5 g 2-propanol, and 72.1 g of 10 mM borate buffer (pH 9.2), eight target analytes could be separated in under 25 min employing a diode-array detector to segregate the overlapping signals obtained for Eusolex 9020 and Eusolex HMS. Detection limits from 0.8 to 6.0 nug/mL were obtained and the calibration plots were linear over at least one order of magnitude. The optimized method could be applied to the determination of Eusolex 6300 and Eusolex 9020 in a commercial suntan lotion.
Laser scribe optimization study. Final report
Wannamaker, A.L.
1996-09-01
The laser scribe characterization/optimization project was initiated to better understand what factors influence response variables of the laser marking process. The laser marking system is utilized to indelibly identify weapon system components. Many components have limited field life, and traceability to production origin is critical. In many cases, the reliability of the weapon system and the safety of the users can be attributed to individual and subassembly component fabrication processes. Laser beam penetration of the substrate material may affect product function. The design agency for the DOE had requested that Federal Manufacturing and Technologies characterize the laser marking process and implement controls on critical process parameters.
Negotiating Story Entry: A Micro-Analytic Study of Storytelling Projection in English and Japanese
ERIC Educational Resources Information Center
Yasui, Eiko
2011-01-01
This dissertation offers a micro-analytic study of the use of language and body during storytelling in American English and Japanese conversations. Specifically, I focus on its beginning and explore how a story is "projected." A beginning of an action or activity is where an incipient speaker negotiates the floor with co-participants; they…
Do Premarital Education Programs Really Work? A Meta-Analytic Study
ERIC Educational Resources Information Center
Fawcett, Elizabeth B.; Hawkins, Alan J.; Blanchard, Victoria L.; Carroll, Jason S.
2010-01-01
Previous studies (J. S. Carroll & W. J. Doherty, 2003) have asserted that premarital education programs have a positive effect on program participants. Using meta-analytic methods of current best practices to look across the entire body of published and unpublished evaluation research on premarital education, we found a more complex pattern of…
ERIC Educational Resources Information Center
Heckel, Robert V.; Mandell, Elizabeth
1981-01-01
A factor analytic study of the behavioral and demographic variables that describe male and female juvenile offenders in a southern correctional facility identified 10 factors for females and six for males. Items clustered much as anticipated for both groups, with family conflicts and individual neurotic traits forming clusters. (Author)
An Analytical Approach to Study Educational Inequalities: 10 Hypothesis Tests in PIRLS 2006
ERIC Educational Resources Information Center
Caro, Daniel H.; Lenkeit, Jenny
2012-01-01
The paper draws on the work of Willms [2006. "Learning divides: Ten policy questions about the performance and equity of schools and schooling systems." Montreal: UNESCO Institute for Statistics] to present an analytical approach to the study of academic achievement disparities related to family socioeconomic status. The approach is illustrated by…
ERIC Educational Resources Information Center
Calvert, Carol Elaine
2014-01-01
This case study relates to distance learning students on open access courses. It demonstrates the use of predictive analytics to generate a model of the probabilities of success and retention at different points, or milestones, in a student journey. A core set of explanatory variables has been established and their varying relative importance at…
ERIC Educational Resources Information Center
Lam, Paul; McNaught, Carmel; Cheng, Kin-Fai
2008-01-01
This paper explores the concept of pragmatic meta-analytic studies in eLearning. Much educational technology literature focuses on developers and teachers describing and reflecting on their experiences. Few connections are made between these experiential "stories". The data set is fragmented and offers few generalisable lessons. The field needs…
Evidence of the Existence of Noctcaelador across Three Measures: A Factor Analytic Study
ERIC Educational Resources Information Center
Kelly, William E.
2006-01-01
This study factor analytically examined the convergence of three questionnaires used in previous research to measure night-sky related attitudes and behaviors in a sample of 72 college students. One factor emerged accounting for the majority of variance in responses. It was concluded that the single factor found across separate measures used in…
The Effects of Incentives on Workplace Performance: A Meta-Analytic Review of Research Studies
ERIC Educational Resources Information Center
Condly, Steven J.; Clark, Richard E.; Stolovitch, Harold D.
2003-01-01
A meta-analytic review of all adequately designed field and laboratory research on the use of incentives to motivate performance is reported. Of approximately 600 studies, 45 qualified. The overall average effect of all incentive programs in all work settings and on all work tasks was a 22% gain in performance. Team-directed incentives had a…
Experimental and analytical studies for the NASA carbon fiber risk assessment
NASA Technical Reports Server (NTRS)
1980-01-01
Various experimental and analytical studies performed for the NASA carbon fiber risk assessment program are described with emphasis on carbon fiber characteristics, sensitivity of electrical equipment and components to shorting or arcing by carbon fibers, attenuation effect of carbon fibers on aircraft landing aids, impact of carbon fibers on industrial facilities. A simple method of estimating damage from airborne carbon fibers is presented.
Adequacy of surface analytical tools for studying the tribology of ceramics
NASA Technical Reports Server (NTRS)
Sliney, H. E.
1986-01-01
Surface analytical tools are very beneficial in tribological studies of ceramics. Traditional methods of optical microscopy, XRD, XRF, and SEM should be combined with newer surface sensitive techniques especially AES and XPS. ISS and SIMS can also be useful in providing additional compositon details. Tunneling microscopy and electron energy loss spectroscopy are less known techniques that may also prove useful.
Setting analytical performance specifications based on outcome studies - is it possible?
Horvath, Andrea Rita; Bossuyt, Patrick M M; Sandberg, Sverre; John, Andrew St; Monaghan, Phillip J; Verhagen-Kamerbeek, Wilma D J; Lennartz, Lieselotte; Cobbaert, Christa M; Ebert, Christoph; Lord, Sarah J
2015-05-01
The 1st Strategic Conference of the European Federation of Clinical Chemistry and Laboratory Medicine proposed a simplified hierarchy for setting analytical performance specifications (APS). The top two levels of the 1999 Stockholm hierarchy, i.e., evaluation of the effect of analytical performance on clinical outcomes and clinical decisions have been proposed to be replaced by one outcome-based model. This model can be supported by: (1a) direct outcome studies; and (1b) indirect outcome studies investigating the impact of analytical performance of the test on clinical classifications or decisions and thereby on the probability of patient relevant clinical outcomes. This paper reviews the need for outcome-based specifications, the most relevant types of outcomes to be considered, and the challenges and limitations faced when setting outcome-based APS. The methods of Model 1a and b are discussed and examples are provided for how outcome data can be translated to APS using the linked evidence and simulation or decision analytic techniques. Outcome-based APS should primarily reflect the clinical needs of patients; should be tailored to the purpose, role and significance of the test in a well defined clinical pathway; and should be defined at a level that achieves net health benefit for patients at reasonable costs. Whilst it is acknowledged that direct evaluations are difficult and may not be possible for all measurands, all other forms of setting APS should be weighed against that standard, and regarded as approximations. Better definition of the relationship between the analytical performance of tests and health outcomes can be used to set analytical performance criteria that aim to improve the clinical and cost-effectiveness of laboratory tests.
A semi-analytical study on helical springs made of shape memory polymer
NASA Astrophysics Data System (ADS)
Baghani, M.; Naghdabadi, R.; Arghavani, J.
2012-04-01
In this paper, the responses of shape memory polymer (SMP) helical springs under axial force are studied both analytically and numerically. In the analytical solution, we first derive the response of a cylindrical tube under torsional loadings. This solution can be used for helical springs in which both the curvature and pitch effects are negligible. This is the case for helical springs with large ratios of the mean coil radius to the cross sectional radius (spring index) and also small pitch angles. Making use of this solution simplifies the analysis of the helical springs to that of the torsion of a straight bar with circular cross section. The 3D phenomenological constitutive model recently proposed for SMPs is also reduced to the 1D shear case. Thus, an analytical solution for the torsional response of SMP tubes in a full cycle of stress-free strain recovery is derived. In addition, the curvature effect is added to the formulation and the SMP helical spring is analyzed using the exact solution presented for torsion of curved SMP tubes. In this modified solution, the effect of the direct shear force is also considered. In the numerical analysis, the 3D constitutive equations are implemented in a finite element program and a full cycle of stress-free strain recovery of an SMP (extension or compression) helical spring is simulated. Analytical and numerical results are compared and it is shown that the analytical solution gives accurate stress distributions in the cross section of the helical SMP spring besides the global load-deflection response. Some case studies are presented to show the validity of the presented analytical method.
A KBE-enabled design framework for cost/weight optimization study of aircraft composite structures
NASA Astrophysics Data System (ADS)
Wang, H.; La Rocca, G.; van Tooren, M. J. L.
2014-10-01
Traditionally, minimum weight is the objective when optimizing airframe structures. This optimization, however, does not consider the manufacturing cost which actually determines the profit of the airframe manufacturer. To this purpose, a design framework has been developed able to perform cost/weight multi-objective optimization of an aircraft component, including large topology variations of the structural configuration. The key element of the proposed framework is a dedicated knowledge based engineering (KBE) application, called multi-model generator, which enables modelling very different product configurations and variants and extract all data required to feed the weight and cost estimation modules, in a fully automated fashion. The weight estimation method developed in this research work uses Finite Element Analysis to calculate the internal stresses of the structural elements and an analytical composite plate sizing method to determine their minimum required thicknesses. The manufacturing cost estimation module was developed on the basis of a cost model available in literature. The capability of the framework was successfully demonstrated by designing and optimizing the composite structure of a business jet rudder. The study case indicates the design framework is able to find the Pareto optimal set for minimum structural weight and manufacturing costin a very quick way. Based on the Pareto set, the rudder manufacturer is in conditions to conduct both internal trade-off studies between minimum weight and minimum cost solutions, as well as to offer the OEM a full set of optimized options to choose, rather than one feasible design.
Analytical stability and simulation response study for a coupled two-body system
NASA Technical Reports Server (NTRS)
Tao, K. M.; Roberts, J. R.
1975-01-01
An analytical stability study and a digital simulation response study of two connected rigid bodies are documented. Relative rotation of the bodies at the connection is allowed, thereby providing a model suitable for studying system stability and response during a soft-dock regime. Provisions are made of a docking port axes alignment torque and a despin torque capability for encountering spinning payloads. Although the stability analysis is based on linearized equations, the digital simulation is based on nonlinear models.
Aeroelastic Optimization Study Based on X-56A Model
NASA Technical Reports Server (NTRS)
Li, Wesley; Pak, Chan-Gi
2014-01-01
A design process which incorporates the object-oriented multidisciplinary design, analysis, and optimization (MDAO) tool and the aeroelastic effects of high fidelity finite element models to characterize the design space was successfully developed and established. Two multidisciplinary design optimization studies using an object-oriented MDAO tool developed at NASA Armstrong Flight Research Center were presented. The first study demonstrates the use of aeroelastic tailoring concepts to minimize the structural weight while meeting the design requirements including strength, buckling, and flutter. A hybrid and discretization optimization approach was implemented to improve accuracy and computational efficiency of a global optimization algorithm. The second study presents a flutter mass balancing optimization study. The results provide guidance to modify the fabricated flexible wing design and move the design flutter speeds back into the flight envelope so that the original objective of X-56A flight test can be accomplished.
NASA Astrophysics Data System (ADS)
Novotný, K.; Kaiser, J.; Galiová, M.; Konečná, V.; Novotný, J.; Malina, R.; Liška, M.; Kanický, V.; Otruba, V.
2008-10-01
Laser-ablation based analytical techniques represent a simple way for fast chemical analysis of different materials. In this work, an exploratory study of multi-element (Ca, Al, Fe, Mn) mappings of a granite sample surface was performed by laser-induced breakdown spectroscopy (LIBS) and subsequently by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis. The operating parameters (e.g. pulse energy, ablation-crater size) were optimized for both techniques in order to achieve the appropriate conditions for two-dimensional high-resolution compositional mappings of mineral microstructures in large sample areas. The sample was scanned with 100 × 100 individual sample points to map an area of 20 × 20 mm 2. The normalized signals were used for construct of contour plots which were colored according local distribution of the selected elements. The results of two laser-based methods were compared and found to be similar.
NASA Astrophysics Data System (ADS)
Baskonus, Haci Mehmet; Bulut, Hasan
2015-10-01
In this study, we have studied to obtain some new analytical solutions to the (1 + 1)-dimensional nonlinear Dispersive Modified Benjamin-Bona-Mahony equation by using modified exp-function method. We have submitted the general structure of modified exp-function method. We have founded some new analytical solutions such as hyperbolic and rational function solutions. Afterward, we have plotted 2D and 3D surfaces of analytical solutions obtained in this study by using computer programming wolfram Mathematica 9.
Effects of pre-analytical processes on blood samples used in metabolomics studies.
Yin, Peiyuan; Lehmann, Rainer; Xu, Guowang
2015-07-01
Every day, analytical and bio-analytical chemists make sustained efforts to improve the sensitivity, specificity, robustness, and reproducibility of their methods. Especially in targeted and non-targeted profiling approaches, including metabolomics analysis, these objectives are not easy to achieve; however, robust and reproducible measurements and low coefficients of variation (CV) are crucial for successful metabolomics approaches. Nevertheless, all efforts from the analysts are in vain if the sample quality is poor, i.e. if preanalytical errors are made by the partner during sample collection. Preanalytical risks and errors are more common than expected, even when standard operating procedures (SOP) are used. This risk is particularly high in clinical studies, and poor sample quality may heavily bias the CV of the final analytical results, leading to disappointing outcomes of the study and consequently, although unjustified, to critical questions about the analytical performance of the approach from the partner who provided the samples. This review focuses on the preanalytical phase of liquid chromatography-mass spectrometry-driven metabolomics analysis of body fluids. Several important preanalytical factors that may seriously affect the profile of the investigated metabolome in body fluids, including factors before sample collection, blood drawing, subsequent handling of the whole blood (transportation), processing of plasma and serum, and inadequate conditions for sample storage, will be discussed. In addition, a detailed description of latent effects on the stability of the blood metabolome and a suggestion for a practical procedure to circumvent risks in the preanalytical phase will be given.
Collisional evolution - an analytical study for the non steady-state mass distribution.
NASA Astrophysics Data System (ADS)
Vieira Martins, R.
1999-05-01
To study the collisional evolution of asteroidal groups one can use an analytical solution for the self-similar collision cascades. This solution is suitable to study the steady-state mass distribution of the collisional fragmentation. However, out of the steady-state conditions, this solution is not satisfactory for some values of the collisional parameters. In fact, for some values for the exponent of the mass distribution power law of an asteroidal group and its relation to the exponent of the function which describes "how rocks break" the author arrives at singular points for the equation which describes the collisional evolution. These singularities appear since some approximations are usually made in the laborious evaluation of many integrals that appear in the analytical calculations. They concern the cutoff for the smallest and the largest bodies. These singularities set some restrictions to the study of the analytical solution for the collisional equation. To overcome these singularities the author performed an algebraic computation considering the smallest and the largest bodies and he obtained the analytical expressions for the integrals that describe the collisional evolution without restriction on the parameters. However, the new distribution is more sensitive to the values of the collisional parameters. In particular the steady-state solution for the differential mass distribution has exponents slightly different from 11/6 for the usual parameters in the asteroid belt. The sensitivity of this distribution with respect to the parameters is analyzed for the usual values in the asteroidal groups. With an expression for the mass distribution without singularities, one can evaluate also its time evolution. The author arrives at an analytical expression given by a power series of terms constituted by a small parameter multiplied by the mass to an exponent, which depends on the initial power law distribution. This expression is a formal solution for the
Ammar, Hafedh Belhadj; Brahim, Mabrouk Ben; Abdelhédi, Ridha; Samet, Youssef
2016-02-01
The performance of boron-doped diamond (BDD) electrode for the detection of metronidazole (MTZ) as the most important drug of the group of 5-nitroimidazole was proven using cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques. A comparison study between BDD, glassy carbon and silver electrodes on the electrochemical response was carried out. The process is pH-dependent. In neutral and alkaline media, one irreversible reduction peak related to the hydroxylamine derivative formation was registered, involving a total of four electrons. In acidic medium, a prepeak appears probably related to the adsorption affinity of hydroxylamine at the electrode surface. The BDD electrode showed higher sensitivity and reproducibility analytical response, compared with the other electrodes. The higher reduction peak current was registered at pH11. Under optimal conditions, a linear analytical curve was obtained for the MTZ concentration in the range of 0.2-4.2μmolL(-1), with a detection limit of 0.065μmolL(-1).
Pesin, Yakov B.; Niu, Xun; Latash, Mark L.
2010-01-01
We consider the problem of what is being optimized in human actions with respect to various aspects of human movements and different motor tasks. From the mathematical point of view this problem consists of finding an unknown objective function given the values at which it reaches its minimum. This problem is called the inverse optimization problem. Until now the main approach to this problems has been the cut-and-try method, which consists of introducing an objective function and checking how it reflects the experimental data. Using this approach, different objective functions have been proposed for the same motor action. In the current paper we focus on inverse optimization problems with additive objective functions and linear constraints. Such problems are typical in human movement science. The problem of muscle (or finger) force sharing is an example. For such problems we obtain sufficient conditions for uniqueness and propose a method for determining the objective functions. To illustrate our method we analyze the problem of force sharing among the fingers in a grasping task. We estimate the objective function from the experimental data and show that it can predict the force-sharing pattern for a vast range of external forces and torques applied to the grasped object. The resulting objective function is quadratic with essentially non-zero linear terms. PMID:19902213
Analytical and numerical study of Gauss-Bonnet holographic superconductors with Power-Maxwell field
NASA Astrophysics Data System (ADS)
Sheykhi, Ahmad; Salahi, Hamid Reza; Montakhab, Afshin
2016-04-01
We provide an analytical as well as a numerical study of the holographic s-wave superconductors in Gauss-Bonnet gravity with Power-Maxwell electrodynamics. We limit our study to the case where scalar and gauge fields do not have an effect on the background metric. We use a variational method, based on Sturm-Liouville eigenvalue problem for our analytical study, as well as a numerical shooting method in order to compare with our analytical results. Interestingly enough, we observe that unlike Born-Infeld-like nonlinear electrodynamics which decrease the critical temperature compared to the linear Maxwell field, the Power-Maxwell electrodynamics is able to increase the critical temperature of the holographic superconductors in the sublinear regime. We find that requiring the finite value for the gauge field on the asymptotic boundary r → ∞, restricts the power parameter, q, of the Power-Maxwell field to be in the range 1 /2 < q < ( d - 1) /2. Our study indicates that it is quite possible to make condensation easier as q decreases in its allowed range. We also find that for all values of q, the condensation can be affected by the Gauss-Bonnet coefficient α. However, the presence of the Gauss-Bonnet term makes the transition slightly harder. Finally, we obtain an analytic expression for the order parameter and thus obtain the associated critical exponent near the phase transition. We find that the critical exponent has its universal value of β = 1 /2 regardless of the parameters q, α as well as dimension d, consistent with mean-field values obtained in previous studies.
Genetic association studies between SNPs and suicidal behavior: a meta-analytical field synopsis.
Schild, Anne H E; Pietschnig, Jakob; Tran, Ulrich S; Voracek, Martin
2013-10-01
The large number of published meta-analyses on the associations between single-nucleotide polymorphisms (SNPs) and suicidal behavior mirrors the enormous research interest in this topic. Although meta-analytic evidence is abundant and certain patterns are apparent, those have not been integrated into a general framework as of yet. In a systematic review, genetic association studies between SNPs and suicidal behavior were identified. Previously published meta-analyses for eight SNPs were updated and the results of the different meta-analyses were compared. Meta-analyses for 15 SNPs, which had not been subjected to meta-analysis before, were conducted. The present meta-analytical field synopsis showed five major similarities between new and published analyses: 1) Summary effect sizes were small and rarely statistically significant, 2) heterogeneity between studies was often substantial, 3) there were no time trends, 4) effects were easily swayed and were largely dependent on individual studies, and 5) publication bias does not play a role in this field of research. Meta-analytic data show once more that major contributions of single genes are unlikely. However, association studies and corresponding meta-analyses have been an important and necessary stepping stone in the development of modern and more complex approaches in the genetics of suicidal behavior.
Experimental and analytical study of high velocity impact on Kevlar/Epoxy composite plates
NASA Astrophysics Data System (ADS)
Sikarwar, Rahul; Velmurugan, Raman; Madhu, Velmuri
2012-12-01
In the present study, impact behavior of Kevlar/Epoxy composite plates has been carried out experimentally by considering different thicknesses and lay-up sequences and compared with analytical results. The effect of thickness, lay-up sequence on energy absorbing capacity has been studied for high velocity impact. Four lay-up sequences and four thickness values have been considered. Initial velocities and residual velocities are measured experimentally to calculate the energy absorbing capacity of laminates. Residual velocity of projectile and energy absorbed by laminates are calculated analytically. The results obtained from analytical study are found to be in good agreement with experimental results. It is observed from the study that 0/90 lay-up sequence is most effective for impact resistance. Delamination area is maximum on the back side of the plate for all thickness values and lay-up sequences. The delamination area on the back is maximum for 0/90/45/-45 laminates compared to other lay-up sequences.
Vandermause, Roxanne; Barbosa-Leiker, Celestina; Fritz, Roschelle
2014-12-01
This multimethod, qualitative study provides results for educators of nursing doctoral students to consider. Combining the expertise of an empirical analytical researcher (who uses statistical methods) and an interpretive phenomenological researcher (who uses hermeneutic methods), a course was designed that would place doctoral students in the midst of multiparadigmatic discussions while learning fundamental research methods. Field notes and iterative analytical discussions led to patterns and themes that highlight the value of this innovative pedagogical application. Using content analysis and interpretive phenomenological approaches, together with one of the students, data were analyzed from field notes recorded in real time over the period the course was offered. This article describes the course and the study analysis, and offers the pedagogical experience as transformative. A link to a sample syllabus is included in the article. The results encourage nurse educators of doctoral nursing students to focus educational practice on multiple methodological perspectives. PMID:25406843
Game analytics for game user research, part 1: a workshop review and case study.
El-Nasr, Magy Seif; Desurvire, Heather; Aghabeigi, Bardia; Drachen, Anders
2013-01-01
The emerging field of game user research (GUR) investigates interaction between players and games and the surrounding context of play. Game user researchers have explored methods from, for example, human-computer interaction, psychology, interaction design, media studies, and the social sciences. They've extended and modified these methods for different types of digital games, such as social games, casual games, and serious games. This article focuses on quantitative analytics of in-game behavioral user data and its emergent use by the GUR community. The article outlines open problems emerging from several GUR workshops. In addition, a case study of a current collaboration between researchers and a game company demonstrates game analytics' use and benefits.
Vandermause, Roxanne; Barbosa-Leiker, Celestina; Fritz, Roschelle
2014-12-01
This multimethod, qualitative study provides results for educators of nursing doctoral students to consider. Combining the expertise of an empirical analytical researcher (who uses statistical methods) and an interpretive phenomenological researcher (who uses hermeneutic methods), a course was designed that would place doctoral students in the midst of multiparadigmatic discussions while learning fundamental research methods. Field notes and iterative analytical discussions led to patterns and themes that highlight the value of this innovative pedagogical application. Using content analysis and interpretive phenomenological approaches, together with one of the students, data were analyzed from field notes recorded in real time over the period the course was offered. This article describes the course and the study analysis, and offers the pedagogical experience as transformative. A link to a sample syllabus is included in the article. The results encourage nurse educators of doctoral nursing students to focus educational practice on multiple methodological perspectives.
Optimal Trend Tests for Genetic Association Studies of Heterogeneous Diseases.
Lee, Wen-Chung
2016-06-09
The Cochran-Armitage trend test is a standard procedure in genetic association studies. It is a directed test with high power to detect genetic effects that follow the gene-dosage model. In this paper, the author proposes optimal trend tests for genetic association studies of heterogeneous diseases. Monte-Carlo simulations show that the power gain of the optimal trend tests over the conventional Cochran-Armitage trend test is striking when the genetic effects are heterogeneous. The easy-to-use R 3.1.2 software (R Foundation for Statistical Computing, Vienna, Austria) code is provided. The optimal trend tests are recommended for routine use.
[Migration and health--developing an explanatory and analytical model for epidemiological studies].
Schenk, Liane
2007-01-01
Migrant status, including ethnic minority status, is an important determinant of health inequalities. Previous studies point to a complex, multifactorial relationship between migration and health, however current explanatory approaches focus mostly on the effects of single determinants. In this article, an explanatory and analytical model of migration and health will be developed in an effort to structure and integrate previous approaches by drawing upon existing definitions of the target population and theories of the relationship between migration and health status.
NASA Astrophysics Data System (ADS)
Lohner, T.; Agócs, E.; Petrik, P.; Zolnai, Z.; Szilágyi, E.; Kovács, I.; Szőkefalvi-Nagy, Z.; Tóth, L.; Tóth, A. L.; Illés, L.; Bársony, I.
2014-11-01
In this work recently produced and commercially available glazed ceramic object with metallic lustre decoration was studied by using a spectroscopic ellipsometer with rotating compensator. The thickness and metal content of the surface lustre layers are determined by ion beam analytical techniques, i.e., Rutherford backscattering spectrometry and external beam particle-induced X-ray emission and the results were utilized in the construction of multilayer optical models for the evaluation and interpretation of the spectroellipsometric measurements.
An analytical and numerical study of chaotic dynamics in a simple bouncing ball model
NASA Astrophysics Data System (ADS)
Okninski, Andrzej; Radziszewski, Bogusław
2011-02-01
Dynamics of a ball moving in gravitational field and colliding with a moving table is studied in this paper. The motion of the limiter is assumed as periodic with piecewise constant velocity—it is assumed that the table moves up with a constant velocity and then moves down with another constant velocity. The Poincaré map, describing evolution from an impact to the next impact, is derived and scenarios of transition to chaotic dynamics are investigated analytically and numerically.
Evaluation of Lauha bhasma on classical analytical parameters - A pilot study.
Sarkar, Prasanta Kumar; Choudhary, A K; Prajapati, P K
2008-01-01
Lauha Bhasma is the most widely used bhasma preparation in therapeutics, but till date the temperature pattern to prepare Lauha Bhasma in electric muffle furnace is not fixed. So in this pilot study an attempt has been made to confirm the appropriate temperature pattern to prepare Lauha Bhasma. And emphasis has been given to evaluate this prepared Lauha Bhasma on classical analytical parameter, which reflects the physical and chemical properties of the Bhasma. PMID:22557274
Evaluation of Lauha bhasma on classical analytical parameters – A pilot study
Sarkar, Prasanta Kumar; Choudhary, A. K.; Prajapati, P. K.
2008-01-01
Lauha Bhasma is the most widely used bhasma preparation in therapeutics, but till date the temperature pattern to prepare Lauha Bhasma in electric muffle furnace is not fixed. So in this pilot study an attempt has been made to confirm the appropriate temperature pattern to prepare Lauha Bhasma. And emphasis has been given to evaluate this prepared Lauha Bhasma on classical analytical parameter, which reflects the physical and chemical properties of the Bhasma. PMID:22557274
An analytical study on the carrier-phase linear combinations for triple-frequency GNSS
NASA Astrophysics Data System (ADS)
Li, Jinlong; Yang, Yuanxi; He, Haibo; Guo, Hairong
2016-08-01
The linear combinations of multi-frequency carrier-phase measurements for Global Navigation Satellite System (GNSS) are greatly beneficial to improving the performance of ambiguity resolution (AR), cycle slip correction as well as precise positioning. In this contribution, the existing definitions of the carrier-phase linear combination are reviewed and the integer property of the resulting ambiguity of the phase linear combinations is examined. The general analytical method for solving the optimal integer linear combinations for all triple-frequency GNSS is presented. Three refined triple-frequency integer combinations solely determined by the frequency values are introduced, which are the ionosphere-free (IF) combination that the Sum of its integer coefficients equal to 0 (IFS0), the geometry-free (GF) combination that the Sum of its integer coefficients equal to 0 (GFS0) and the geometry-free and ionosphere-free (GFIF) combination. Besides, the optimal GF, IF, extra-wide lane and ionosphere-reduced integer combinations for GPS and BDS are solved exhaustively by the presented method. Their potential applications in cycle slip detection, AR as well as precise positioning are discussed. At last, a more straightforward GF and IF AR scheme than the existing method is presented based on the GFIF integer combination.
NASA Technical Reports Server (NTRS)
Starbuck, J. Michael; Guerdal, Zafer; Pindera, Marek-Jerzy; Poe, Clarence C.
1990-01-01
Damage states in laminated composites were studied by considering the model problem of a laminated beam subjected to three-point bending. A combination of experimental and theoretical research techniques was used to correlate the experimental results with the analytical stress distributions. The analytical solution procedure was based on the stress formulation approach of the mathematical theory of elasticity. The solution procedure is capable of calculating the ply-level stresses and beam displacements for any laminated beam of finite length using the generalized plane deformation or plane stress state assumption. Prior to conducting the experimental phase, the results from preliminary analyses were examined. Significant effects in the ply-level stress distributions were seen depending on the fiber orientation, aspect ratio, and whether or not a grouped or interspersed stacking sequence was used. The experimental investigation was conducted to determine the different damage modes in laminated three-point bend specimens. The test matrix consisted of three-point bend specimens of 0 deg unidirectional, cross-ply, and quasi-isotropic stacking sequences. The dependence of the damage initiation loads and ultimate failure loads were studied, and their relation to damage susceptibility and damage tolerance of the mean configuration was discussed. Damage modes were identified by visual inspection of the damaged specimens using an optical microscope. The four fundamental damage mechanisms identified were delaminations, matrix cracking, fiber breakage, and crushing. The correlation study between the experimental results and the analytical results were performed for the midspan deflection, indentation, damage modes, and damage susceptibility.
Analytical bunch compression studies for a linac-based electron accelerator
NASA Astrophysics Data System (ADS)
Schreck, M.; Wesolowski, P.
2015-10-01
The current paper deals with analytical bunch compression studies for FLUTE whose results are compared to simulations. FLUTE is a linac-based electron accelerator with a design energy of approximately 40 MeV currently being constructed at the Karlsruhe Institute of Technology. One of the goals of FLUTE is to generate electron bunches with their length lying in the femtosecond regime. In the first phase this will be accomplished using a magnetic bunch compressor. This compressor forms the subject of the studies presented. The paper is divided into two parts. The first part deals with pure geometric investigations of the bunch compressor where space charge effects and the backreaction of bunches with coherent synchrotron radiation are neglected. The second part is dedicated to the treatment of space charge effects. The upshot is that the analytical results in the two parts agree quite well with what is obtained from simulations. This paper shall form the basis for future analytical studies of the FLUTE bunch compressor and of bunch compression, in general.
A study of commuter airplane design optimization
NASA Technical Reports Server (NTRS)
Roskam, J.; Wyatt, R. D.; Griswold, D. A.; Hammer, J. L.
1977-01-01
Problems of commuter airplane configuration design were studied to affect a minimization of direct operating costs. Factors considered were the minimization of fuselage drag, methods of wing design, and the estimated drag of an airplane submerged in a propellor slipstream; all design criteria were studied under a set of fixed performance, mission, and stability constraints. Configuration design data were assembled for application by a computerized design methodology program similar to the NASA-Ames General Aviation Synthesis Program.
Do dental students use optimal study strategies?
McAndrew, Maureen; Kamboj, Rajit S; Pierre, Gaëlle C
2015-01-01
Research on human learning has shown that repeated retrieval practice or self-testing maximizes learning. However, recent studies have found undergraduate students to be largely unaware of the benefits of self-testing. The aim of this study was to examine dental students' study strategies and utilization of retrieval techniques for learning. All second-year dental students at New York University College of Dentistry were invited to participate. Of the total 360 students, 66 completed the two-question survey, for a response rate of 18.3%. The first question asked students to choose from a list of twelve study strategies the ones they used and to rank their top five in order of personal preference. Repeated reading was the most frequently used strategy with 83.3% of students reporting that they used it and 43.9% naming it as their top strategy. Of these students, 45.5% indicated that they self-tested while studying, but none indicated it was their number one strategy. The second question asked students how they would study after reading a textbook chapter for the first time. They were asked to choose one option from three possibilities: going back and restudying, self-testing (with the possibility of restudying afterward), or some other strategy. On this question, 25.8% chose restudying, 45.5% chose self-testing, and 28.8% indicated they would use another study strategy. Thus, 54.6% of the students reported they would not test themselves after reading a textbook chapter. Of those who chose self-testing, only seven students indicated they would do so to improve learning. The results of this study suggest that the students lacked sufficient awareness of the superiority of self-testing for learning.
Do dental students use optimal study strategies?
McAndrew, Maureen; Kamboj, Rajit S; Pierre, Gaëlle C
2015-01-01
Research on human learning has shown that repeated retrieval practice or self-testing maximizes learning. However, recent studies have found undergraduate students to be largely unaware of the benefits of self-testing. The aim of this study was to examine dental students' study strategies and utilization of retrieval techniques for learning. All second-year dental students at New York University College of Dentistry were invited to participate. Of the total 360 students, 66 completed the two-question survey, for a response rate of 18.3%. The first question asked students to choose from a list of twelve study strategies the ones they used and to rank their top five in order of personal preference. Repeated reading was the most frequently used strategy with 83.3% of students reporting that they used it and 43.9% naming it as their top strategy. Of these students, 45.5% indicated that they self-tested while studying, but none indicated it was their number one strategy. The second question asked students how they would study after reading a textbook chapter for the first time. They were asked to choose one option from three possibilities: going back and restudying, self-testing (with the possibility of restudying afterward), or some other strategy. On this question, 25.8% chose restudying, 45.5% chose self-testing, and 28.8% indicated they would use another study strategy. Thus, 54.6% of the students reported they would not test themselves after reading a textbook chapter. Of those who chose self-testing, only seven students indicated they would do so to improve learning. The results of this study suggest that the students lacked sufficient awareness of the superiority of self-testing for learning. PMID:25576550
Analytical study of the liquid phase transient behavior of a high temperature heat pipe. M.S. Thesis
NASA Technical Reports Server (NTRS)
Roche, Gregory Lawrence
1988-01-01
The transient operation of the liquid phase of a high temperature heat pipe is studied. The study was conducted in support of advanced heat pipe applications that require reliable transport of high temperature drops and significant distances under a broad spectrum of operating conditions. The heat pipe configuration studied consists of a sealed cylindrical enclosure containing a capillary wick structure and sodium working fluid. The wick is an annular flow channel configuration formed between the enclosure interior wall and a concentric cylindrical tube of fine pore screen. The study approach is analytical through the solution of the governing equations. The energy equation is solved over the pipe wall and liquid region using the finite difference Peaceman-Rachford alternating direction implicit numerical method. The continuity and momentum equations are solved over the liquid region by the integral method. The energy equation and liquid dynamics equation are tightly coupled due to the phase change process at the liquid-vapor interface. A kinetic theory model is used to define the phase change process in terms of the temperature jump between the liquid-vapor surface and the bulk vapor. Extensive auxiliary relations, including sodium properties as functions of temperature, are used to close the analytical system. The solution procedure is implemented in a FORTRAN algorithm with some optimization features to take advantage of the IBM System/370 Model 3090 vectorization facility. The code was intended for coupling to a vapor phase algorithm so that the entire heat pipe problem could be solved. As a test of code capabilities, the vapor phase was approximated in a simple manner.
A multiobjective shape optimization study for a subsonic submerged inlet
NASA Astrophysics Data System (ADS)
Taskinoglu, Ezgi S.
The purpose of the present work is to summarize the findings of a multiobjective shape optimization study conducted for a subsonic submerged air vehicle inlet. The objective functions of the optimization problem are distortion and swirl indices defined by the distribution of flow parameters over the exit cross-section of the inlet. The geometry alteration is performed by placing a protrusion in the shape of a fin on the baseline inlet surface. Thus, the design variables of the optimization problem are chosen to be the geometrical parameters defining the fin protrusion; namely fin height, length and incidence angle. The Trade Off (also known as epsilon-constraint) method is employed for finding the Pareto optimal set formed by the nondominated solutions of the feasible design space. Since the flow domain solution is required for every step along the line search, an automated optimization loop is constructed by integrating the optimizer with a surface modeler, a mesh generator and a flow solver through which the flow parameters over the compressor face are computed. In addition, the trade study for fin protrusion, the analyses and the comparison of the baseline and Pareto optimal solutions are presented and observations concerning grid resolution and convergence behaviour are discussed. The results display an irregular and discontinuous Pareto optimal set. Optimum inlet designs are scattered in two regions from which one representative inlet design is chosen and analyzed. As a result, it is concluded that an inlet designer has two options within the framework of this optimization study: an inlet design with high swirl but low distortion or an inlet design with low swirl but higher distortion.
An analytical pipeline for genomic representations used for cytosine methylation studies
Thompson, Reid F.; Reimers, Mark; Khulan, Batbayar; Gissot, Mathieu; Richmond, Todd A.; Chen, Quan; Zheng, Xin; Kim, Kami
2016-01-01
Motivation Representations of the genome can be generated by the selection of a subpopulation of restriction fragments using ligation-mediated PCR. Such representations form the basis for a number of high-throughput assays, including the HELP assay to study cytosine methylation. We find that HELP data analysis is complicated not only by PCR amplification heterogeneity but also by a complex and variable distribution of cytosine methylation. To address this, we created an analytical pipeline and novel normalization approach that improves concordance between microarray-derived data and single locus validation results, demonstrating the value of the analytical approach. A major influence on the PCR amplification is the size of the restriction fragment, requiring a quantile normalization approach that reduces the influence of fragment length on signal intensity. Here we describe all of the components of the pipeline, which can also be applied to data derived from other assays based on genomic representations. PMID:18353789
Mohd Sultan, Norfazila; Johan, Mohd Rafie
2014-01-01
Gold nanoparticles (AuNPs) had been synthesized with various molarities and weights of reducing agent, monosodium glutamate (MSG), and stabilizer chitosan, respectively. The significance of chitosan as stabilizer was distinguished through transmission electron microscopy (TEM) images and UV-Vis absorption spectra in which the interparticles distance increases whilst retaining the surface plasmon resonance (SPR) characteristics peak. The most stable AuNPs occurred for composition with the lowest (1 g) weight of chitosan. AuNPs capped with chitosan size stayed small after 1 month aging compared to bare AuNPs. The ability of chitosan capped AuNPs to uptake analyte was studied by employing amorphous carbon nanotubes (α-CNT), copper oxide (Cu2O), and zinc sulphate (ZnSO4) as the target material. The absorption spectra showed dramatic intensity increased and red shifted once the analyte was added to the chitosan capped AuNPs.
Study of a vibrating plate: comparison between experimental (ESPI) and analytical results
NASA Astrophysics Data System (ADS)
Romero, G.; Alvarez, L.; Alanís, E.; Nallim, L.; Grossi, R.
2003-07-01
Real-time electronic speckle pattern interferometry (ESPI) was used for tuning and visualization of natural frequencies of a trapezoidal plate. The plate was excited to resonant vibration by a sinusoidal acoustical source, which provided a continuous range of audio frequencies. Fringe patterns produced during the time-average recording of the vibrating plate—corresponding to several resonant frequencies—were registered. From these interferograms, calculations of vibrational amplitudes by means of zero-order Bessel functions were performed in some particular cases. The system was also studied analytically. The analytical approach developed is based on the Rayleigh-Ritz method and on the use of non-orthogonal right triangular co-ordinates. The deflection of the plate is approximated by a set of beam characteristic orthogonal polynomials generated by using the Gram-Schmidt procedure. A high degree of correlation between computational analysis and experimental results was observed.
Molecular motion in cell membranes: Analytic study of fence-hindered random walks
NASA Astrophysics Data System (ADS)
Kenkre, V. M.; Giuggioli, L.; Kalay, Z.
2008-05-01
A theoretical calculation is presented to describe the confined motion of transmembrane molecules in cell membranes. The study is analytic, based on Master equations for the probability of the molecules moving as random walkers, and leads to explicit usable solutions including expressions for the molecular mean square displacement and effective diffusion constants. One outcome is a detailed understanding of the dependence of the time variation of the mean square displacement on the initial placement of the molecule within the confined region. How to use the calculations is illustrated by extracting (confinement) compartment sizes from experimentally reported published observations from single particle tracking experiments on the diffusion of gold-tagged G -protein coupled μ -opioid receptors in the normal rat kidney cell membrane, and by further comparing the analytical results to observations on the diffusion of phospholipids, also in normal rat kidney cells.
A semi-analytical study of positive corona discharge in wire-plane electrode configuration
NASA Astrophysics Data System (ADS)
Yanallah, K.; Pontiga, F.; Chen, J. H.
2013-08-01
Wire-to-plane positive corona discharge in air has been studied using an analytical model of two species (electrons and positive ions). The spatial distributions of electric field and charged species are obtained by integrating Gauss's law and the continuity equations of species along the Laplacian field lines. The experimental values of corona current intensity and applied voltage, together with Warburg's law, have been used to formulate the boundary condition for the electron density on the corona wire. To test the accuracy of the model, the approximate electric field distribution has been compared with the exact numerical solution obtained from a finite element analysis. A parametrical study of wire-to-plane corona discharge has then been undertaken using the approximate semi-analytical solutions. Thus, the spatial distributions of electric field and charged particles have been computed for different values of the gas pressure, wire radius and electrode separation. Also, the two dimensional distribution of ozone density has been obtained using a simplified plasma chemistry model. The approximate semi-analytical solutions can be evaluated in a negligible computational time, yet provide precise estimates of corona discharge variables.
NASA Astrophysics Data System (ADS)
Zhou, L. X.; Li, K.
2015-08-01
Existing droplet evaporation/combustion models in computational fluid dynamics (CFD) simulation of spray combustion are based on simplified 1-D models. Both these models and recently developed 3-D models of single-droplet combustion do not give the conditions for the different existing droplet combustion modes. In this paper, droplet evaporation and combustion are studied both analytically and numerically. In the analytical solution, a 2-D axisymmetric flow surrounding an evaporating and combusting droplet was considered. The governing equations were solved using an integral method, similar to the Karman-Pohlhausen method for solving boundary-layer flows with pressure gradient. The results give a local evaporation rate and flame radius in agreement with experimental results. In numerical simulation, 3-D combusting gas flows surrounding an ethanol droplet were studied. The prediction results show three modes of droplet combustion under different relative velocities, explaining the change in the evaporation constant with an increase in relative velocity observed in experiments. This implies that different droplet combustion models should be developed in simulating spray combustion. The predicted local evaporation rate and flame radius by numerical simulation are in agreement with the analytical solution in the range of azimuthal angles . The numerical results indicate that the drag force of an evaporating and combusting droplet is much smaller than that of a cold solid particle, and thus the currently used drag models should be modified.
Starmer, C F; Biktashev, V N; Romashko, D N; Stepanov, M R; Makarova, O N; Krinsky, V I
1993-01-01
Cardiac tissue can display unusual responses to certain stimulation protocols. In the wake of a conditioning wave of excitation, spiral waves can be initiated by applying stimuli timed to occur during a period of vulnerability (VP). Although vulnerability is well known in cardiac and chemical media, the determinants of the VP and its boundaries have received little theoretical and analytical study. From numerical and analytical studies of reaction-diffusion equations, we have found that 1) vulnerability is an inherent property of Beeler-Reuter and FitzHugh-Nagumo models of excitable media; 2) the duration of the vulnerable window (VW) the one-dimensional analog of the VP, is sensitive to the medium properties and the size of the stimulus field; and 3) the amplitudes of the excitatory and recovery processes modulate the duration of the VW. The analytical results reveal macroscopic behavior (vulnerability) derived from the diffusion of excitation that is not observable at the level of isolated cells or single reaction units. PMID:8298011
NASA Astrophysics Data System (ADS)
Zhang, Li; Liu, Xi-Feng; Yuan, Wen; Wang, Xiao-Tian
2014-06-01
A new analytical perturbation method is developed in this study to investigate the general reflection coefficients in the frequency-wavenumber domain of the acoustic field in a fluid-filled borehole surrounded by a transversely isotropic medium (TIM). The transversely isotropic medium with a symmetric axis parallel to the borehole axis, which is usually called a VTI medium, was adopted because its exact solutions exists, and a corresponding isotropic medium was adopted as a reference state of perturbation solution. The general reflection coefficients were originally calculated by using the perturbation method and were compared with the analytical solutions. The zero-, first- and second-order perturbation solutions for the general reflection coefficients excited by monopole, dipole and quadrupole sources were investigated for a transversely isotropic elastic solid. The results showed that the general reflection coefficients obtained by using the perturbation solutions and the analytical solutions were similar for all three sources. In summary, our study demonstrated that the perturbation method is valid and effective in acoustical logging. This work provided a theoretical foundation for extending perturbation analyses to complicated anisotropic acoustical logging applications.
A prospective study of hope, optimism, and health.
Scioli, A; Chamberlin, C M; Samor, C M; Lapointe, A B; Campbell, T L; MacLeod, A R; McLenon, J
1997-12-01
The present investigation sought to distinguish hope from optimism in the context of a 10-wk. prospective study involving reports of health outcomes. Gottschalk's (1985) Hope Scale and Scheier and Carver's (1987) Life Orientation Test which assesses optimism were given to subjects, along with a health questionnaire. Ten weeks later subjects were given a second health questionnaire. To rule out potential confounds we included measures of neuroticism, depression, extroversion, and social desirability. After controlling for the effects of correlated confounds, we found that lower hope scores (but not optimism) were correlated with several dimensions of reported health, including frequency and severity of illness.
Optimization study of third harmonic generation in quantum cascade lasers.
Mojibpour, Ali; Pourfath, Mahdi; Kosina, Hans
2014-08-25
A systematic optimization study of quantum cascade lasers with integrated nonlinearity for third-harmonic generation is performed. To model current transport the Pauli master equation is solved using a Monte Carlo approach. A multi-objective particle swarm optimization algorithm is applied to obtain the Pareto front. Our theoretical analysis indicates an optimized structure with five orders of magnitude increase in the generated third-harmonic power with respect to the reference design. This striking performance comes with a low threshold current density of about 1.6 kA/cm2 and is attributed to double resonant phonon scattering assisted extraction and injection scheme of the laser.
Power supply standardization and optimization study
NASA Technical Reports Server (NTRS)
Ware, C. L.; Ragusa, E. V.
1972-01-01
A comprehensive design study of a power supply for use in the space shuttle and other space flight applications is presented. The design specifications are established for a power supply capable of supplying over 90 percent of the anticipated voltage requirements for future spacecraft avionics systems. Analyses and tradeoff studies were performed on several alternative design approaches to assure that the selected design would provide near optimum performance of the planned applications. The selected design uses a dc-to-dc converter incorporating regenerative current feedback with a time-ratio controlled duty cycle to achieve high efficiency over a wide variation in input voltage and output loads. The packaging concept uses an expandable mainframe capable of accommodating up to six inverter/regulator modules with one common input filter module.
NASA Astrophysics Data System (ADS)
Kaniewski, Jedrzej
2016-08-01
Self-testing refers to the phenomenon that certain extremal quantum correlations (almost) uniquely identify the quantum system under consideration. For instance, observing the maximal violation of the Clauser-Horne-Shimony-Holt (CHSH) inequality certifies that the two parties share a singlet. While self-testing results are known for several classes of states, in many cases they are only applicable if the observed statistics are almost perfect, which makes them unsuitable for practical applications. Practically relevant self-testing bounds are much less common and moreover they all result from a single numerical method (with one exception which we discuss in detail). In this work we present a new technique for proving analytic self-testing bounds of practically relevant robustness. We obtain improved bounds for the case of self-testing the singlet using the CHSH inequality (in particular we show that nontrivial fidelity with the singlet can be achieved as long as the violation exceeds β*=(16 +14 √{2 })/17 ≈2.11 ). In the case of self-testing the tripartite Greenberger-Horne-Zeilinger state using the Mermin inequality, we derive a bound which not only improves on previously known results but turns out to be tight. We discuss other scenarios to which our technique can be immediately applied.
Kaniewski, Jędrzej
2016-08-12
Self-testing refers to the phenomenon that certain extremal quantum correlations (almost) uniquely identify the quantum system under consideration. For instance, observing the maximal violation of the Clauser-Horne-Shimony-Holt (CHSH) inequality certifies that the two parties share a singlet. While self-testing results are known for several classes of states, in many cases they are only applicable if the observed statistics are almost perfect, which makes them unsuitable for practical applications. Practically relevant self-testing bounds are much less common and moreover they all result from a single numerical method (with one exception which we discuss in detail). In this work we present a new technique for proving analytic self-testing bounds of practically relevant robustness. We obtain improved bounds for the case of self-testing the singlet using the CHSH inequality (in particular we show that nontrivial fidelity with the singlet can be achieved as long as the violation exceeds β^{*}=(16+14sqrt[2])/17≈2.11). In the case of self-testing the tripartite Greenberger-Horne-Zeilinger state using the Mermin inequality, we derive a bound which not only improves on previously known results but turns out to be tight. We discuss other scenarios to which our technique can be immediately applied. PMID:27563939
Barati, Ali; Shamsipur, Mojtaba; Arkan, Elham; Hosseinzadeh, Leila; Abdollahi, Hamid
2015-02-01
Herein, a facile hydrothermal treatment of lime juice to prepare biocompatible nitrogen-doped carbon quantum dots (N-CQDs) in the presence of ammonium bicarbonate as a nitrogen source has been presented. The resulting N-CQDs exhibited excitation and pH independent emission behavior; with the quantum yield (QY) up to 40%, which was several times greater than the corresponding value for CQDs with no added nitrogen source. The N-CQDs were applied as a fluorescent probe for the sensitive and selective detection of Hg(2+) ions with a detection limit of 14 nM. Moreover, the cellular uptake and cytotoxicity of N-CQDs at different concentration ranges from 0.0 to 0.8 mg/ml were investigated by using PC12 cells as a model system. Response surface methodology was used for optimization and systematic investigation of the main variables that influence the QY, including reaction time, reaction temperature, and ammonium bicarbonate weight.
Sharon, Maheshwar; Apte, P R; Purandare, S C; Zacharia, Renju
2005-02-01
Seven variable parameters of the chemical vapor deposition system have been optimized with the help of the Taguchi analytical method for getting a desired product, e.g., carbon nanotubes or carbon nanobeads. It is observed that almost all selected parameters influence the growth of carbon nanotubes. However, among them, the nature of precursor (racemic, R or Technical grade camphor) and the carrier gas (hydrogen, argon and mixture of argon/hydrogen) seem to be more important parameters affecting the growth of carbon nanotubes. Whereas, for the growth of nanobeads, out of seven parameters, only two, i.e., catalyst (powder of iron, cobalt, and nickel) and temperature (1023 K, 1123 K, and 1273 K), are the most influential parameters. Systematic defects or islands on the substrate surface enhance nucleation of novel carbon materials. Quantitative contributions of process parameters as well as optimum factor levels are obtained by performing analysis of variance (ANOVA) and analysis of mean (ANOM), respectively. PMID:15853150
Phonon dispersion on Ag (100) surface: A modified analytic embedded atom method study
NASA Astrophysics Data System (ADS)
Xiao-Jun, Zhang; Chang-Le, Chen
2016-01-01
Within the harmonic approximation, the analytic expression of the dynamical matrix is derived based on the modified analytic embedded atom method (MAEAM) and the dynamics theory of surface lattice. The surface phonon dispersions along three major symmetry directions , and X¯M¯ are calculated for the clean Ag (100) surface by using our derived formulas. We then discuss the polarization and localization of surface modes at points X¯ and M¯ by plotting the squared polarization vectors as a function of the layer index. The phonon frequencies of the surface modes calculated by MAEAM are compared with the available experimental and other theoretical data. It is found that the present results are generally in agreement with the referenced experimental or theoretical results, with a maximum deviation of 10.4%. The agreement shows that the modified analytic embedded atom method is a reasonable many-body potential model to quickly describe the surface lattice vibration. It also lays a significant foundation for studying the surface lattice vibration in other metals. Project supported by the National Natural Science Foundation of China (Grant Nos. 61471301 and 61078057), the Scientific Research Program Funded by Shaanxi Provincial Education Department, China (Grant No. 14JK1301), and the Specialized Research Fund for the Doctoral Program of Higher Education, China (Grant No. 20126102110045).
Experimental and analytical study of close-coupled ventral nozzles for ASTOVL aircraft
NASA Technical Reports Server (NTRS)
Mcardle, Jack G.; Smith, C. Frederic
1990-01-01
Flow in a generic ventral nozzle system was studied experimentally and analytically with a block version of the PARC3D computational fluid dynamics program (a full Navier-Stokes equation solver) in order to evaluate the program's ability to predict system performance and internal flow patterns. For the experimental work a one-third-size model tailpipe with a single large rectangular ventral nozzle mounted normal to the tailpipe axis was tested with unheated air at steady-state pressure ratios up to 4.0. The end of the tailpipe was closed to simulate a blocked exhaust nozzle. Measurements showed about 5 1/2 percent flow-turning loss, reasonable nozzle performance coefficients, and a significant aftward axial component of thrust due to flow turning loss, reasonable nozzle performance coefficients, and a significant aftward axial component of thrust due to flow turning more than 90 deg. Flow behavior into and through the ventral duct is discussed and illustrated with paint streak flow visualization photographs. For the analytical work the same ventral system configuration was modeled with two computational grids to evaluate the effect of grid density. Both grids gave good results. The finer-grid solution produced more detailed flow patterns and predicted performance parameters, such as thrust and discharge coefficient, within 1 percent of the measured values. PARC3D flow visualization images are shown for comparison with the paint streak photographs. Modeling and computational issues encountered in the analytical work are discussed.
NASA Technical Reports Server (NTRS)
Rais-Rohani, Masoud
1991-01-01
In this paper an effort is made to improve the analytical open-loop flutter predictions for the Active Flexible Wing wind-tunnel model using a sensitivity based optimization approach. The sensitivity derivatives of the flutter frequency and dynamic pressure of the model with respect to the lag terms appearing in the Roger's unsteady aerodynamics approximations are evaluated both analytical and by finite differences. Then, the Levenberg-Marquardt method is used to find the optimum values for these lag-terms. The results obtained here agree much better with the experimental (wind tunnel) results than those found in the previous studies.
NASA Technical Reports Server (NTRS)
Prasthofer, W. P.
1974-01-01
The key to optimization of design where there are a large number of variables, all of which may not be known precisely, lies in the mathematical tool of dynamic programming developed by Bellman. This methodology can lead to optimized solutions to the design of critical systems in a minimum amount of time, even when there are a great number of acceptable configurations to be considered. To demonstrate the usefulness of dynamic programming, an analytical method is developed for evaluating the relationship among existing numerous connector designs to find the optimum configuration. The data utilized in the study were generated from 900 flanges designed for six subsystems of the S-1B stage of the Saturn 1B space carrier vehicle.
Not Available
2006-06-01
In the Analytical Microscopy group, within the National Center for Photovoltaic's Measurements and Characterization Division, we combine two complementary areas of analytical microscopy--electron microscopy and proximal-probe techniques--and use a variety of state-of-the-art imaging and analytical tools. We also design and build custom instrumentation and develop novel techniques that provide unique capabilities for studying materials and devices. In our work, we collaborate with you to solve materials- and device-related R&D problems. This sheet summarizes the uses and features of four major tools: transmission electron microscopy, scanning electron microscopy, the dual-beam focused-ion-beam workstation, and scanning probe microscopy.
Carver, Charles S.; Scheier, Michael F.; Segerstrom, Suzanne C.
2010-01-01
Optimism is an individual difference variable that reflects the extent to which people hold generalized favorable expectancies for their future. Higher levels of optimism have been related prospectively to better subjective well-being in times of adversity or difficulty (i.e., controlling for previous well-being). Consistent with such findings, optimism has been linked to higher levels of engagement coping and lower levels of avoidance, or disengagement, coping. There is evidence that optimism is associated with taking proactive steps to protect one's health, whereas pessimism is associated with health-damaging behaviors. Consistent with such findings, optimism is also related to indicators of better physical health. The energetic, task-focused approach that optimists take to goals also relates to benefits in the socioeconomic world. Some evidence suggests that optimism relates to more persistence in educational efforts and to higher later income. Optimists also appear to fare better than pessimists in relationships. Although there are instances in which optimism fails to convey an advantage, and instances in which it may convey a disadvantage, those instances are relatively rare. In sum, the behavioral patterns of optimists appear to provide models of living for others to learn from. PMID:20170998
NASA Astrophysics Data System (ADS)
Yttri, K. E.; Schnelle-Kreis, J.; Maenhaut, W.; Abbaszade, G.; Alves, C.; Bjerke, A.; Bonnier, N.; Bossi, R.; Claeys, M.; Dye, C.; Evtyugina, M.; García-Gacio, D.; Hillamo, R.; Hoffer, A.; Hyder, M.; Iinuma, Y.; Jaffrezo, J.-L.; Kasper-Giebl, A.; Kiss, G.; López-Mahia, P. L.; Pio, C.; Piot, C.; Ramirez-Santa-Cruz, C.; Sciare, J.; Teinilä, K.; Vermeylen, R.; Vicente, A.; Zimmermann, R.
2015-01-01
The monosaccharide anhydrides (MAs) levoglucosan, galactosan and mannosan are products of incomplete combustion and pyrolysis of cellulose and hemicelluloses, and are found to be major constituents of biomass burning (BB) aerosol particles. Hence, ambient aerosol particle concentrations of levoglucosan are commonly used to study the influence of residential wood burning, agricultural waste burning and wildfire emissions on ambient air quality. A European-wide intercomparison on the analysis of the three monosaccharide anhydrides was conducted based on ambient aerosol quartz fiber filter samples collected at a Norwegian urban background site during winter. Thus, the samples' content of MAs is representative for BB particles originating from residential wood burning. The purpose of the intercomparison was to examine the comparability of the great diversity of analytical methods used for analysis of levoglucosan, mannosan and galactosan in ambient aerosol filter samples. Thirteen laboratories participated, of which three applied high-performance anion-exchange chromatography (HPAEC), four used high-performance liquid chromatography (HPLC) or ultra-performance liquid chromatography (UPLC) and six resorted to gas chromatography (GC). The analytical methods used were of such diversity that they should be considered as thirteen different analytical methods. All of the thirteen laboratories reported levels of levoglucosan, whereas nine reported data for mannosan and/or galactosan. Eight of the thirteen laboratories reported levels for all three isomers. The accuracy for levoglucosan, presented as the mean percentage error (PE) for each participating laboratory, varied from -63 to 20%; however, for 62% of the laboratories the mean PE was within ±10%, and for 85% the mean PE was within ±20%. For mannosan, the corresponding range was -60 to 69%, but as for levoglucosan, the range was substantially smaller for a subselection of the laboratories; i.e. for 33% of the
NASA Astrophysics Data System (ADS)
Yttri, K. E.; Schnelle-Kreiss, J.; Maenhaut, W.; Alves, C.; Bossi, R.; Bjerke, A.; Claeys, M.; Dye, C.; Evtyugina, M.; García-Gacio, D.; Gülcin, A.; Hillamo, R.; Hoffer, A.; Hyder, M.; Iinuma, Y.; Jaffrezo, J.-L.; Kasper-Giebl, A.; Kiss, G.; López-Mahia, P. L.; Pio, C.; Piot, C.; Ramirez-Santa-Cruz, C.; Sciare, J.; Teinilä, K.; Vermeylen, R.; Vicente, A.; Zimmermann, R.
2014-07-01
The monosaccharide anhydrides (MAs) levoglucosan, galactosan and mannosan are products of incomplete combustion and pyrolysis of cellulose and hemicelluloses, and are found to be major constituents of biomass burning aerosol particles. Hence, ambient aerosol particle concentrations of levoglucosan are commonly used to study the influence of residential wood burning, agricultural waste burning and wild fire emissions on ambient air quality. A European-wide intercomparison on the analysis of the three monosaccharide anhydrides was conducted based on ambient aerosol quartz fiber filter samples collected at a Norwegian urban background site during winter. Thus, the samples' content of MAs is representative for biomass burning particles originating from residential wood burning. The purpose of the intercomparison was to examine the comparability of the great diversity of analytical methods used for analysis of levoglucosan, mannosan and galactosan in ambient aerosol filter samples. Thirteen laboratories participated, of which three applied High-Performance Anion-Exchange Chromatography (HPAEC), four used High-Performance Liquid Chromatography (HPLC) or Ultra-Performance Liquid Chromatography (UPLC), and six resorted to Gas Chromatography (GC). The analytical methods used were of such diversity that they should be considered as thirteen different analytical methods. All of the thirteen laboratories reported levels of levoglucosan, whereas nine reported data for mannosan and/or galactosan. Eight of the thirteen laboratories reported levels for all three isomers. The accuracy for levoglucosan, presented as the mean percentage error (PE) for each participating laboratory, varied from -63 to 23%; however, for 62% of the laboratories the mean PE was within ±10%, and for 85% the mean PE was within ±20%. For mannosan, the corresponding range was -60 to 69%, but as for levoglucosan, the range was substantially smaller for a subselection of the laboratories; i.e., for 33% of
NASA Astrophysics Data System (ADS)
Gergely, Felicián; Osán, János; Szabó, B. Katalin; Török, Szabina
2016-02-01
Laboratory-scale microscopic X-ray fluorescence (micro-XRF) plays an increasingly important role in various fields where multielemental investigations of samples are indispensable. In case of geological samples, the reasonable detection limits (LOD) and spatial resolutions are necessary to identify the trace element content in microcrystalline level. The present study focuses on the analytical performance of a versatile laboratory-scale micro-XRF system with various options of X-ray sources and detectors to find the optimal experimental configuration in terms of sensitivities and LOD for selected elements in loaded petrographic thin sections. The method was tested for sorption studies involving thin sections prepared from cores of Boda Claystone Formation, which is a potential site for a high-level radioactive waste repository. Loaded ions in the sorption measurements were Cs(I) and Ni(II) chemically representing fission and corrosion products. Based on the collected elemental maps, the correlation between the elements representative of main rock components and the selected loaded ion was studied. For the elements of interest, Cs(I) and Ni(II) low-power iMOXS source with polycapillary and silicon drift detector was found to be the best configuration to reach the optimal LOD values. Laboratory micro-XRF was excellent to identify the responsible key minerals for the uptake of Cs(I). In case of nickel, careful corrections were needed because of the relatively high Ca content of the rock samples. The results were compared to synchrotron radiation micro-XRF.
NASA Astrophysics Data System (ADS)
Ahmad, N.; Ali, Q.; Ashraf, M.; Alam, B.; Naeem, A.
2012-11-01
Half-Dressed rubble stone (DS) masonry structures as found in the Himalayan region are investigated using experimental and analytical studies. The experimental study included a shake table test on a one-third scaled structural model, a representative of DS masonry structure employed for public critical facilities, e.g. school buildings, offices, health care units, etc. The aim of the experimental study was to understand the damage mechanism of the model, develop damage scale towards deformation-based assessment and retrieve the lateral force-deformation response of the model besides its elastic dynamic properties, i.e. fundamental vibration period and elastic damping. The analytical study included fragility analysis of building prototypes using a fully probabilistic nonlinear dynamic method. The prototypes are designed as SDOF systems assigned with lateral, force-deformation constitutive law (obtained experimentally). Uncertainties in the constitutive law, i.e. lateral stiffness, strength and deformation limits, are considered through random Monte Carlo simulation. Fifty prototype buildings are analyzed using a suite of ten natural accelerograms and an incremental dynamic analysis technique. Fragility and vulnerability functions are derived for the damageability assessment of structures, economic loss and casualty estimation during an earthquake given the ground shaking intensity, essential within the context of risk assessment of existing stock aiming towards risk mitigation and disaster risk reduction.
NASA Astrophysics Data System (ADS)
Mezlini, Salah; Zidi, M.; Arfa, H.; Ben Tkaya, Mohamed; Kapsa, Philippe
2005-11-01
The transport of granular material often generates severe damage. Understanding the correlation between the friction coefficient, particle geometry and wear mechanisms is of primary importance for materials undergoing abrasive wear. The aim of this study is to investigate the effect of particle geometry on wear mechanisms and the friction coefficient. Numerical and analytical simulations and experimental results have been compared. The process to be studied is the scratch made by a rigid cone with different attack angles on a 5xxx aluminium alloy (Al-Mg) flat surface. A scratch test was used and the wear mechanisms were observed for different attack angles. A numerical study with a finite element code was made in order to understand the effect of attack angle on the friction coefficient. The contact surface and the friction coefficient were also studied, and the results compared to the Bowden and Tabor model. The superposition of the numerical, analytical and experimental results showed a better correlation between the wear mechanisms and the friction coefficient. It also showed the importance of the model hypothesis used to simulate the scratch phenomenon. To cite this article: S. Mezlini et al., C. R. Mecanique 333 (2005).
Mahulikar, Shripad P; Potnuru, Santosh K; Kolhe, Pankaj S
2007-08-01
The solid angle (Omega) subtended by the hot power-plant surfaces of a typical fighter aircraft, on the detector of an infrared (IR) guided missile, is analytically obtained. The use of the parallel rays projection method simplifies the incorporation of the effect of the optical blocking by engine surfaces, on Omega-subtended. This methodology enables the evaluation of the relative contribution of the IR signature from well-resolved distributed sources, and is important for imaging infrared detection studies. The complex 3D surface of a rear fuselage is projected onto an equivalent planar area normal to the viewing aspect, which would give the same Omega-subtended. PMID:17676106
In situ analytical electron microscopy studies of redox reactions at a YSZ/Pt interface.
Tavabi, Amir Hossein; Arai, Shigeo; Tanji, Takayoshi
2012-06-01
Redox reactions were studied at a single yttria-stabilized zirconia (YSZ)/Pt electrode interface, in parallel with pure YSZ with no catalyst electrode, by in situ analytical electron microscopy at elevated temperatures and in an oxygen atmosphere. In situ electron holography showed that the oxide underwent reduction at elevated temperatures in a vacuum and was consequently reoxidized upon exposure to an oxygen flux at the same temperature. In situ energy loss spectroscopy measurements were in agreement with in situ electron holography observations and indicated that the oxidation state of the host cation zirconium was altered in the reduced state of the YSZ to the metastable state Zr(3+).
Non-degenerate two-photon absorption in silicon waveguides. Analytical and experimental study
Zhang, Yanbing; Husko, Chad; Lefrancois, Simon; Rey, Isabella H.; Krauss, Thomas F.; Schröder, Jochen; Eggleton, Benjamin J.
2015-06-22
We theoretically and experimentally investigate the nonlinear evolution of two optical pulses in a silicon waveguide. We provide an analytic solution for the weak probe wave undergoing non-degenerate two-photon absorption (TPA) from the strong pump. At larger pump intensities, we employ a numerical solution to study the interplay between TPA and photo-generated free carriers. We develop a simple and powerful approach to extract and separate out the distinct loss contributions of TPA and free-carrier absorption from readily available experimental data. Our analysis accounts accurately for experimental results in silicon photonic crystal waveguides.
Analytical study of the large orbital X-ray telescope imaging system
NASA Technical Reports Server (NTRS)
Foreman, J. W., Jr.; Cardone, J. M.
1973-01-01
Results of an analytical study of the large orbital X-ray telescope (LOXT) are presented. The LOXT consists of a nested array of four conventional paraboloidal-hyperboloidal X-ray telescopes arranged with a common optical axis and a common focal plane. The composite nested array has a nominal effective focal length of 135.0 inches. The equations of the various mirror surfaces and the numerical values of the parameters in the defining equations are given in the technical specification sheets for the LOXT.
NASA Astrophysics Data System (ADS)
Bozkaya, Uǧur; Sherrill, C. David
2013-08-01
Orbital-optimized coupled-electron pair theory [or simply "optimized CEPA(0)," OCEPA(0), for short] and its analytic energy gradients are presented. For variational optimization of the molecular orbitals for the OCEPA(0) method, a Lagrangian-based approach is used along with an orbital direct inversion of the iterative subspace algorithm. The cost of the method is comparable to that of CCSD [O(N6) scaling] for energy computations. However, for analytic gradient computations the OCEPA(0) method is only half as expensive as CCSD since there is no need to solve the λ2-amplitude equation for OCEPA(0). The performance of the OCEPA(0) method is compared with that of the canonical MP2, CEPA(0), CCSD, and CCSD(T) methods, for equilibrium geometries, harmonic vibrational frequencies, and hydrogen transfer reactions between radicals. For bond lengths of both closed and open-shell molecules, the OCEPA(0) method improves upon CEPA(0) and CCSD by 25%-43% and 38%-53%, respectively, with Dunning's cc-pCVQZ basis set. Especially for the open-shell test set, the performance of OCEPA(0) is comparable with that of CCSD(T) (ΔR is 0.0003 Å on average). For harmonic vibrational frequencies of closed-shell molecules, the OCEPA(0) method again outperforms CEPA(0) and CCSD by 33%-79% and 53%-79%, respectively. For harmonic vibrational frequencies of open-shell molecules, the mean absolute error (MAE) of the OCEPA(0) method (39 cm-1) is fortuitously even better than that of CCSD(T) (50 cm-1), while the MAEs of CEPA(0) (184 cm-1) and CCSD (84 cm-1) are considerably higher. For complete basis set estimates of hydrogen transfer reaction energies, the OCEPA(0) method again exhibits a substantially better performance than CEPA(0), providing a mean absolute error of 0.7 kcal mol-1, which is more than 6 times lower than that of CEPA(0) (4.6 kcal mol-1), and comparing to MP2 (7.7 kcal mol-1) there is a more than 10-fold reduction in errors. Whereas the MAE for the CCSD method is only 0.1 kcal
Bozkaya, Uğur; Sherrill, C David
2013-08-01
Orbital-optimized coupled-electron pair theory [or simply "optimized CEPA(0)," OCEPA(0), for short] and its analytic energy gradients are presented. For variational optimization of the molecular orbitals for the OCEPA(0) method, a Lagrangian-based approach is used along with an orbital direct inversion of the iterative subspace algorithm. The cost of the method is comparable to that of CCSD [O(N(6)) scaling] for energy computations. However, for analytic gradient computations the OCEPA(0) method is only half as expensive as CCSD since there is no need to solve the λ2-amplitude equation for OCEPA(0). The performance of the OCEPA(0) method is compared with that of the canonical MP2, CEPA(0), CCSD, and CCSD(T) methods, for equilibrium geometries, harmonic vibrational frequencies, and hydrogen transfer reactions between radicals. For bond lengths of both closed and open-shell molecules, the OCEPA(0) method improves upon CEPA(0) and CCSD by 25%-43% and 38%-53%, respectively, with Dunning's cc-pCVQZ basis set. Especially for the open-shell test set, the performance of OCEPA(0) is comparable with that of CCSD(T) (ΔR is 0.0003 Å on average). For harmonic vibrational frequencies of closed-shell molecules, the OCEPA(0) method again outperforms CEPA(0) and CCSD by 33%-79% and 53%-79%, respectively. For harmonic vibrational frequencies of open-shell molecules, the mean absolute error (MAE) of the OCEPA(0) method (39 cm(-1)) is fortuitously even better than that of CCSD(T) (50 cm(-1)), while the MAEs of CEPA(0) (184 cm(-1)) and CCSD (84 cm(-1)) are considerably higher. For complete basis set estimates of hydrogen transfer reaction energies, the OCEPA(0) method again exhibits a substantially better performance than CEPA(0), providing a mean absolute error of 0.7 kcal mol(-1), which is more than 6 times lower than that of CEPA(0) (4.6 kcal mol(-1)), and comparing to MP2 (7.7 kcal mol(-1)) there is a more than 10-fold reduction in errors. Whereas the MAE for the CCSD method is
NASA Astrophysics Data System (ADS)
Rassoulinejad-Mousavi, S. M.; Abbasbandy, S.; Alsulami, H. H.
2014-08-01
Hydrodynamics of a conducting visco-elastic fluid in a porous medium sandwiched between two parallel plates, under the effect of the Lorentz force, for both moving and stationary wall boundary conditions, is considered in this paper. The non-linear momentum equation is solved analytically using the optimal homotopy analysis method (OHAM) and the effect of existing parameters in the physics of the problem is demonstrated on the dimensionless velocity profile and skin friction coefficient. The robustness of the analytical solution is checked by comparison with numerical results and plotting the residual errors. Results show that there is excellent agreement between numerical and analytical solutions. Furthermore, the error diagrams show that OHAM yields accurate results in all values of the different effective parameters, such as porous medium shape factor, Forchheimer number, visco-elastic parameter, Reynolds number and the parameters related to the Lorentz force.
Delcey, Mickaël G.; Freitag, Leon; González, Leticia; Pedersen, Thomas Bondo; Aquilante, Francesco; Lindh, Roland
2014-05-07
We present a formulation of analytical energy gradients at the complete active space self-consistent field (CASSCF) level of theory employing density fitting (DF) techniques to enable efficient geometry optimizations of large systems. As an example, the ground and lowest triplet state geometries of a ruthenium nitrosyl complex are computed at the DF-CASSCF level of theory and compared with structures obtained from density functional theory (DFT) using the B3LYP, BP86, and M06L functionals. The average deviation of all bond lengths compared to the crystal structure is 0.042 Å at the DF-CASSCF level of theory, which is slightly larger but still comparable with the deviations obtained by the tested DFT functionals, e.g., 0.032 Å with M06L. Specifically, the root-mean-square deviation between the DF-CASSCF and best DFT coordinates, delivered by BP86, is only 0.08 Å for S{sub 0} and 0.11 Å for T{sub 1}, indicating that the geometries are very similar. While keeping the mean energy gradient errors below 0.25%, the DF technique results in a 13-fold speedup compared to the conventional CASSCF geometry optimization algorithm. Additionally, we assess the singlet-triplet energy vertical and adiabatic differences with multiconfigurational second-order perturbation theory (CASPT2) using the DF-CASSCF and DFT optimized geometries. It is found that the vertical CASPT2 energies are relatively similar regardless of the geometry employed whereas the adiabatic singlet-triplet gaps are more sensitive to the chosen triplet geometry.
NASA Technical Reports Server (NTRS)
Betts, W. S., Jr.
1972-01-01
A computer program called HOPI was developed to predict reorientation flow dynamics, wherein liquids move from one end of a closed, partially filled, rigid container to the other end under the influence of container acceleration. The program uses the simplified marker and cell numerical technique and, using explicit finite-differencing, solves the Navier-Stokes equations for an incompressible viscous fluid. The effects of turbulence are also simulated in the program. HOPI can consider curved as well as straight walled boundaries. Both free-surface and confined flows can be calculated. The program was used to simulate five liquid reorientation cases. Three of these cases simulated actual NASA LeRC drop tower test conditions while two cases simulated full-scale Centaur tank conditions. It was concluded that while HOPI can be used to analytically determine the fluid motion in a typical settling problem, there is a current need to optimize HOPI. This includes both reducing the computer usage time and also reducing the core storage required for a given size problem.
Collisional evolution - an analytical study for the nonsteady-state mass distribution
NASA Astrophysics Data System (ADS)
Martins, R. Vieira
1999-05-01
To study the collisional evolution of asteroidal groups we can use an analytical solutionfor the self-similar collision cascades. This solution is suitable to study the steady-state massdistribution of the collisional fragmentation. However, out of the steady-state conditions, thissolution is not satisfactory for some values of the collisional parameters. In fact, for some valuesfor the exponent of the mass distribution power law of an asteroidal group and its relation to theexponent of the function which describes how rocks break we arrive at singular points for theequation which describes the collisional evolution. These singularities appear since someapproximations are usually made in the laborious evaluation of many integrals that appear in theanalytical calculations. They concern the cutoff for the smallest and the largest bodies. Thesesingularities set some restrictions to the study of the analytical solution for the collisionalequation. To overcome these singularities we performed an algebraic computationconsidering the smallest and the largest bodies and we obtained the analytical expressions for theintegrals that describe the collisional evolution without restriction on the parameters. However,the new distribution is more sensitive to the values of the collisional parameters. In particular thesteady-state solution for the differential mass distribution has exponents slightly different from11⧸6 for the usual parameters in the Asteroid Belt. The sensitivity of this distribution with respectto the parameters is analyzed for the usual values in the asteroidal groups. With anexpression for the mass distribution without singularities, we can evaluate also its time evolution.We arrive at an analytical expression given by a power series of terms constituted by a smallparameter multiplied by the mass to an exponent, which depends on the initial power lawdistribution. This expression is a formal solution for the equation which describes the collisionalevolution
An analytical study on the diffraction quality factor of open cavities
Huang, Y. J.; Chu, K. R.; Yeh, L. H.
2014-10-15
Open cavities are often employed as interaction structures in a new generation of coherent millimeter, sub-millimeter, and terahertz (THz) radiation sources called the gyrotron. One of the open ends of the cavity is intended for rapid extraction of the radiation generated by a powerful electron beam. Up to the sub-THz regime, the diffraction loss from this open end dominates over the Ohmic losses on the walls, which results in a much lower diffraction quality factor (Q{sub d}) than the Ohmic quality factor (Q{sub ohm}). Early analytical studies have led to various expressions for Q{sub d} and shed much light on its properties. In this study, we begin with a review of these studies, and then proceed with the derivation of an analytical expression for Q{sub d} accurate to high order. Its validity is verified with numerical solutions for a step-tunable cavity commonly employed for the development of sub-THz and THz gyrotrons. On the basis of the results, a simplified equation is obtained which explicitly expresses the scaling laws of Q{sub d} with respect to mode indices and cavity dimensions.
Conceptual framework for outcomes research studies of hepatitis C: an analytical review.
Sbarigia, Urbano; Denee, Tom R; Turner, Norris G; Wan, George J; Morrison, Alan; Kaufman, Anna S; Rice, Gary; Dusheiko, Geoffrey M
2016-01-01
Hepatitis C virus infection is one of the main causes of chronic liver disease worldwide. Until recently, the standard antiviral regimen for hepatitis C was a combination of an interferon derivative and ribavirin, but a plethora of new antiviral drugs is becoming available. While these new drugs have shown great efficacy in clinical trials, observational studies are needed to determine their effectiveness in clinical practice. Previous observational studies have shown that multiple factors, besides the drug regimen, affect patient outcomes in clinical practice. Here, we provide an analytical review of published outcomes studies of the management of hepatitis C virus infection. A conceptual framework defines the relationships between four categories of variables: health care system structure, patient characteristics, process-of-care, and patient outcomes. This framework can provide a starting point for outcomes studies addressing the use and effectiveness of new antiviral drug treatments. PMID:27313473
Conceptual framework for outcomes research studies of hepatitis C: an analytical review
Sbarigia, Urbano; Denee, Tom R; Turner, Norris G; Wan, George J; Morrison, Alan; Kaufman, Anna S; Rice, Gary; Dusheiko, Geoffrey M
2016-01-01
Hepatitis C virus infection is one of the main causes of chronic liver disease worldwide. Until recently, the standard antiviral regimen for hepatitis C was a combination of an interferon derivative and ribavirin, but a plethora of new antiviral drugs is becoming available. While these new drugs have shown great efficacy in clinical trials, observational studies are needed to determine their effectiveness in clinical practice. Previous observational studies have shown that multiple factors, besides the drug regimen, affect patient outcomes in clinical practice. Here, we provide an analytical review of published outcomes studies of the management of hepatitis C virus infection. A conceptual framework defines the relationships between four categories of variables: health care system structure, patient characteristics, process-of-care, and patient outcomes. This framework can provide a starting point for outcomes studies addressing the use and effectiveness of new antiviral drug treatments. PMID:27313473
Chahine, G.L.; Genoux, P.F.; Johnson, V.E. Jr.; Frederick, G.S.
1984-09-01
Waterjet nozzles (STRATOJETS) have been developed which achieve passive structuring of cavitating submerged jets into discrete ring vortices, and which possess cavitation incipient numbers six times higher than obtained with conventional cavitating jet nozzles. In this study we developed analytical and numerical techniques and conducted experimental work to gain an understanding of the basic phenomena involved. The achievements are: (1) a thorough analysis of the acoustic dynamics of the feed pipe to the nozzle; (2) a theory for bubble ring growth and collapse; (3) a numerical model for jet simulation; (4) an experimental observation and analysis of candidate second-generation low-sigma STRATOJETS. From this study we can conclude that intensification of bubble ring collapse and design of highly resonant feed tubes can lead to improved drilling rates. The models here described are excellent tools to analyze the various parameters needed for STRATOJET optimizations. Further analysis is needed to introduce such important factors as viscosity, nozzle-jet interaction, and ring-target interaction, and to develop the jet simulation model to describe the important fine details of the flow field at the nozzle exit.
Nowak, Paweł Mateusz; Woźniakiewicz, Michał; Kościelniak, Paweł
2016-07-15
In this work cyclodextrin-assisted enantioseparation of warfarin and 10-hydroxywarfarin by CE has been studied from the analytical and thermodynamic points of view. The role of cyclodextrin concentration and temperature has been analyzed in reference to three different analytical parameters, corresponding to selectivity, resolution and resolution/analysis time ratio. The optimal conditions for enantioseparation have been found, they have been selected on the basis of critical difference in electrophoretic mobility and possibly short analysis time. The values of complexation percentage have also been calculated, to provide a link between the state of complexation equilibrium and the effectiveness of enantioseparation. In the optimal conditions the difference in complexation degree between enantiomers reaches 2.5% and 7.3% for warfarin and 10-hydroxywarfarin, respectively. At each temperature the highest enantioresolution is observed when the average complexation degree is close to 50%. In each case complexation is exothermic and driven by some enthalpically favorable process. 10-hydroxywarfarin exerts the stronger affinity to cyclodextrin and the stronger stereoselective effect. The presented results may be helpful in optimization and understanding of chiral separations by CE. PMID:27160739
Trouvé, Hélène; Couturier, Yves; Etheridge, Francis; Saint-Jean, Olivier; Somme, Dominique
2010-01-01
Background The literature on integration indicates the need for an enhanced theorization of institutional integration. This article proposes path dependence as an analytical framework to study the systems in which integration takes place. Purpose PRISMA proposes a model for integrating health and social care services for older adults. This model was initially tested in Quebec. The PRISMA France study gave us an opportunity to analyze institutional integration in France. Methods A qualitative approach was used. Analyses were based on semi-structured interviews with actors of all levels of decision-making, observations of advisory board meetings, and administrative documents. Results Our analyses revealed the complexity and fragmentation of institutional integration. The path dependency theory, which analyzes the change capacity of institutions by taking into account their historic structures, allows analysis of this situation. The path dependency to the Bismarckian system and the incomplete reforms of gerontological policies generate the coexistence and juxtaposition of institutional systems. In such a context, no institution has sufficient ability to determine gerontology policy and build institutional integration by itself. Conclusion Using path dependence as an analytical framework helps to understand the reasons why institutional integration is critical to organizational and clinical integration, and the complex construction of institutional integration in France. PMID:20689740
NASA Astrophysics Data System (ADS)
Wu, Zhiliang; Wang, Shuxin; Zhang, Lianhong; Hu, S. Jack
This paper presents an analytical model of the electrical contact resistance between the carbon paper gas diffusion layers (GDLs) and the graphite bipolar plates (BPPs) in a proton exchange membrane (PEM) fuel cell. The model is developed based on the classical statistical contact theory for a PEM fuel cell, using the same probability distributions of the GDL structure and BPP surface profile as previously described in Wu et al. [Z. Wu, Y. Zhou, G. Lin, S. Wang, S.J. Hu, J. Power Sources 182 (2008) 265-269] and Zhou et al. [Y. Zhou, G. Lin, A.J. Shih, S.J. Hu, J. Power Sources 163 (2007) 777-783]. Results show that estimates of the contact resistance compare favorably with experimental data by Zhou et al. [Y. Zhou, G. Lin, A.J. Shih, S.J. Hu, J. Power Sources 163 (2007) 777-783]. Factors affecting the contact behavior are systematically studied using the analytical model, including the material properties of the two contact bodies and factors arising from the manufacturing processes. The transverse Young's modulus of chopped carbon fibers in the GDL and the surface profile of the BPP are found to be significant to the contact resistance. The factor study also sheds light on the manufacturing requirements of carbon fiber GDLs for a better contact performance in PEM fuel cells.
López Molina, Juan A; Rivera, María J; Trujillo, Macarena; Berjano, Enrique J
2009-04-01
The objectives of this study were to model the temperature progress of a pulsed radiofrequency (RF) power during RF heating of biological tissue, and to employ the hyperbolic heat transfer equation (HHTE), which takes the thermal wave behavior into account, and compare the results to those obtained using the heat transfer equation based on Fourier theory (FHTE). A theoretical model was built based on an active spherical electrode completely embedded in the biological tissue, after which HHTE and FHTE were analytically solved. We found three typical waveforms for the temperature progress depending on the relations between the dimensionless duration of the RF pulse delta(a) and the expression square root of lambda(rho-1), with lambda as the dimensionless thermal relaxation time of the tissue and rho as the dimensionless position. In the case of a unique RF pulse, the temperature at any location was the result of the overlapping of two different heat sources delayed for a duration delta(a) (each heat source being produced by a RF pulse of limitless duration). The most remarkable feature in the HHTE analytical solution was the presence of temperature peaks traveling through the medium at a finite speed. These peaks not only occurred during the RF power switch-on period but also during switch off. Finally, a physical explanation for these temperature peaks is proposed based on the interaction of forward and reverse thermal waves. All-purpose analytical solutions for FHTE and HHTE were obtained during pulsed RF heating of biological tissues, which could be used for any value of pulsing frequency and duty cycle.
Maternal and infant activity: Analytic approaches for the study of circadian rhythm.
Thomas, Karen A; Burr, Robert L; Spieker, Susan
2015-11-01
The study of infant and mother circadian rhythm entails choice of instruments appropriate for use in the home environment as well as selection of analytic approach that characterizes circadian rhythm. While actigraphy monitoring suits the needs of home study, limited studies have examined mother and infant rhythm derived from actigraphy. Among this existing research a variety of analyses have been employed to characterize 24-h rhythm, reducing ability to evaluate and synthesize findings. Few studies have examined the correspondence of mother and infant circadian parameters for the most frequently cited approaches: cosinor, non-parametric circadian rhythm analysis (NPCRA), and autocorrelation function (ACF). The purpose of this research was to examine analytic approaches in the study of mother and infant circadian activity rhythm. Forty-three healthy mother and infant pairs were studied in the home environment over a 72h period at infant age 4, 8, and 12 weeks. Activity was recorded continuously using actigraphy monitors and mothers completed a diary. Parameters of circadian rhythm were generated from cosinor analysis, NPCRA, and ACF. The correlation among measures of rhythm center (cosinor mesor, NPCRA mid level), strength or fit of 24-h period (cosinor magnitude and R(2), NPCRA amplitude and relative amplitude (RA)), phase (cosinor acrophase, NPCRA M10 and L5 midpoint), and rhythm stability and variability (NPCRA interdaily stability (IS) and intradaily variability (IV), ACF) was assessed, and additionally the effect size (eta(2)) for change over time evaluated. Results suggest that cosinor analysis, NPCRA, and autocorrelation provide several comparable parameters of infant and maternal circadian rhythm center, fit, and phase. IS and IV were strongly correlated with the 24-h cycle fit. The circadian parameters analyzed offer separate insight into rhythm and differing effect size for the detection of change over time. Findings inform selection of analysis and
Maternal and infant activity: Analytic approaches for the study of circadian rhythm.
Thomas, Karen A; Burr, Robert L; Spieker, Susan
2015-11-01
The study of infant and mother circadian rhythm entails choice of instruments appropriate for use in the home environment as well as selection of analytic approach that characterizes circadian rhythm. While actigraphy monitoring suits the needs of home study, limited studies have examined mother and infant rhythm derived from actigraphy. Among this existing research a variety of analyses have been employed to characterize 24-h rhythm, reducing ability to evaluate and synthesize findings. Few studies have examined the correspondence of mother and infant circadian parameters for the most frequently cited approaches: cosinor, non-parametric circadian rhythm analysis (NPCRA), and autocorrelation function (ACF). The purpose of this research was to examine analytic approaches in the study of mother and infant circadian activity rhythm. Forty-three healthy mother and infant pairs were studied in the home environment over a 72h period at infant age 4, 8, and 12 weeks. Activity was recorded continuously using actigraphy monitors and mothers completed a diary. Parameters of circadian rhythm were generated from cosinor analysis, NPCRA, and ACF. The correlation among measures of rhythm center (cosinor mesor, NPCRA mid level), strength or fit of 24-h period (cosinor magnitude and R(2), NPCRA amplitude and relative amplitude (RA)), phase (cosinor acrophase, NPCRA M10 and L5 midpoint), and rhythm stability and variability (NPCRA interdaily stability (IS) and intradaily variability (IV), ACF) was assessed, and additionally the effect size (eta(2)) for change over time evaluated. Results suggest that cosinor analysis, NPCRA, and autocorrelation provide several comparable parameters of infant and maternal circadian rhythm center, fit, and phase. IS and IV were strongly correlated with the 24-h cycle fit. The circadian parameters analyzed offer separate insight into rhythm and differing effect size for the detection of change over time. Findings inform selection of analysis and
Genetic studies of plasma analytes identify novel potential biomarkers for several complex traits
Deming, Yuetiva; Xia, Jian; Cai, Yefei; Lord, Jenny; Del-Aguila, Jorge L.; Fernandez, Maria Victoria; Carrell, David; Black, Kathleen; Budde, John; Ma, ShengMei; Saef, Benjamin; Howells, Bill; Bertelsen, Sarah; Bailey, Matthew; Ridge, Perry G.; Hefti, Franz; Fillit, Howard; Zimmerman, Earl A.; Celmins, Dzintra; Brown, Alice D.; Carrillo, Maria; Fleisher, Adam; Reeder, Stephanie; Trncic, Nadira; Burke, Anna; Tariot, Pierre; Reiman, Eric M.; Chen, Kewei; Sabbagh, Marwan N.; Beiden, Christine M.; Jacobson, Sandra A.; Sirrel, Sherye A.; Doody, Rachelle S.; Villanueva-Meyer, Javier; Chowdhury, Munir; Rountree, Susan; Dang, Mimi; Kowall, Neil; Killiany, Ronald; Budson, Andrew E.; Norbash, Alexander; Johnson, Patricia Lynn; Green, Robert C.; Marshall, Gad; Johnson, Keith A.; Sperling, Reisa A.; Snyder, Peter; Salloway, Stephen; Malloy, Paul; Correia, Stephen; Bernick, Charles; Munic, Donna; Stern, Yaakov; Honig, Lawrence S.; Bell, Karen L.; Relkin, Norman; Chaing, Gloria; Ravdin, Lisa; Paul, Steven; Flashman, Laura A.; Seltzer, Marc; Hynes, Mary L.; Santulli, Robert B.; Bates, Vernice; Capote, Horacio; Rainka, Michelle; Friedl, Karl; Murali Doraiswamy, P.; Petrella, Jeffrey R.; Borges-Neto, Salvador; James, Olga; Wong, Terence; Coleman, Edward; Schwartz, Adam; Cellar, Janet S.; Levey, Allan L.; Lah, James J.; Behan, Kelly; Scott Turner, Raymond; Johnson, Kathleen; Reynolds, Brigid; Pearlson, Godfrey D.; Blank, Karen; Anderson, Karen; Obisesan, Thomas O.; Wolday, Saba; Allard, Joanne; Lerner, Alan; Ogrocki, Paula; Tatsuoka, Curtis; Fatica, Parianne; Farlow, Martin R.; Saykin, Andrew J.; Foroud, Tatiana M.; Shen, Li; Faber, Kelly; Kim, Sungeun; Nho, Kwangsik; Marie Hake, Ann; Matthews, Brandy R.; Brosch, Jared R.; Herring, Scott; Hunt, Cynthia; Albert, Marilyn; Onyike, Chiadi; D’Agostino, Daniel; Kielb, Stephanie; Graff-Radford, Neill R; Parfitt, Francine; Kendall, Tracy; Johnson, Heather; Petersen, Ronald; Jack, Clifford R.; Bernstein, Matthew; Borowski, Bret; Gunter, Jeff; Senjem, Matt; Vemuri, Prashanthi; Jones, David; Kantarci, Kejal; Ward, Chad; Mason, Sara S.; Albers, Colleen S.; Knopman, David; Johnson, Kris; Chertkow, Howard; Hosein, Chris; Mintzer, Jacob; Spicer, Kenneth; Bachman, David; Grossman, Hillel; Mitsis, Effie; Pomara, Nunzio; Hernando, Raymundo; Sarrael, Antero; Potter, William; Buckholtz, Neil; Hsiao, John; Kittur, Smita; Galvin, James E.; Cerbone, Brittany; Michel, Christina A.; Pogorelec, Dana M.; Rusinek, Henry; de Leon, Mony J; Glodzik, Lidia; De Santi, Susan; Johnson, Nancy; Chuang-Kuo; Kerwin, Diana; Bonakdarpour, Borna; Weintraub, Sandra; Grafman, Jordan; Lipowski, Kristine; Mesulam, Marek-Marsel; Scharre, Douglas W.; Kataki, Maria; Adeli, Anahita; Kaye, Jeffrey; Quinn, Joseph; Silbert, Lisa; Lind, Betty; Carter, Raina; Dolen, Sara; Borrie, Michael; Lee, T-Y; Bartha, Rob; Martinez, Walter; Villena, Teresa; Sadowsky, Carl; Khachaturian, Zaven; Ott, Brian R.; Querfurth, Henry; Tremont, Geoffrey; Frank, Richard; Fleischman, Debra; Arfanakis, Konstantinos; Shah, Raj C.; deToledo-Morrell, Leyla; Sorensen, Greg; Finger, Elizabeth; Pasternack, Stephen; Rachinsky, Irina; Drost, Dick; Rogers, John; Kertesz, Andrew; Furst, Ansgar J.; Chad, Stevan; Yesavage, Jerome; Taylor, Joy L.; Lane, Barton; Rosen, Allyson; Tinklenberg, Jared; Black, Sandra; Stefanovic, Bojana; Caldwell, Curtis; Robin Hsiung, Ging-Yuek; Mudge, Benita; Assaly, Michele; Fox, Nick; Schultz, Susan K.; Boles Ponto, Laura L.; Shim, Hyungsub; Ekstam Smith, Karen; Burns, Jeffrey M.; Swerdlow, Russell H.; Brooks, William M.; Marson, Daniel; Griffith, Randall; Clark, David; Geldmacher, David; Brockington, John; Roberson, Erik; Natelson Love, Marissa; DeCarli, Charles; Carmichael, Owen; Olichney, John; Maillard, Pauline; Fletcher, Evan; Nguyen, Dana; Preda, Andrian; Potkin, Steven; Mulnard, Ruth A.; Thai, Gaby; McAdams-Ortiz, Catherine; Landau, Susan; Jagust, William; Apostolova, Liana; Tingus, Kathleen; Woo, Ellen; Silverman, Daniel H.S.; Lu, Po H.; Bartzokis, George; Thompson, Paul; Donohue, Michael; Thomas, Ronald G.; Walter, Sarah; Gessert, Devon; Brewer, James; Vanderswag, Helen; Sather, Tamie; Jiminez, Gus; Balasubramanian, Archana B.; Mason, Jennifer; Sim, Iris; Aisen, Paul; Davis, Melissa; Morrison, Rosemary; Harvey, Danielle; Thal, Lean; Beckett, Laurel; Neylan, Thomas; Finley, Shannon; Weiner, Michael W.; Hayes, Jacqueline; Rosen, Howard J.; Miller, Bruce L.; Perry, David; Massoglia, Dino; Brawman-Mentzer, Olga; Schuff, Norbert; Smith, Charles D.; Hardy, Peter; Sinha, Partha; Oates, Elizabeth; Conrad, Gary; Koeppe, Robert A.; Lord, Joanne L.; Heidebrink, Judith L.; Arnold, Steven E.; Karlawish, Jason H.; Wolk, David; Clark, Christopher M.; Trojanowki, John Q.; Shaw, Leslie M.; Lee, Virginia; Korecka, Magdalena; Figurski, Michal; Toga, Arthur W.; Crawford, Karen; Neu, Scott; Schneider, Lon S.; Pawluczyk, Sonia; Beccera, Mauricio; Teodoro, Liberty; Spann, Bryan M.; Womack, Kyle; Mathews, Dana; Quiceno, Mary; Foster, Norm; Montine, Tom; Fruehling, J. Jay; Harding, Sandra; Johnson, Sterling; Asthana, Sanjay; Carlsson, Cynthia M.; Petrie, Eric C.; Peskind, Elaine; Li, Gail; Porsteinsson, Anton P.; Goldstein, Bonnie S.; Martin, Kim; Makino, Kelly M.; Ismail, M. Saleem; Brand, Connie; Smith, Amanda; Ashok Raj, Balebail; Fargher, Kristin; Kuller, Lew; Mathis, Chet; Ann Oakley, Mary; Lopez, Oscar L.; Simpson, Donna M.; Sink, Kaycee M.; Gordineer, Leslie; Williamson, Jeff D.; Garg, Pradeep; Watkins, Franklin; Cairns, Nigel J.; Raichle, Marc; Morris, John C.; Householder, Erin; Taylor-Reinwald, Lisa; Holtzman, David; Ances, Beau; Carroll, Maria; Creech, Mary L.; Franklin, Erin; Mintun, Mark A.; Schneider, Stacy; Oliver, Angela; Duara, Ranjan; Varon, Daniel; Greig, Maria T.; Roberts, Peggy; Varma, Pradeep; MacAvoy, Martha G.; Carson, Richard E.; van Dyck, Christopher H.; Davies, Peter; Holtzman, David; Morris, John C.; Bales, Kelly; Pickering, Eve H.; Lee, Jin-Moo; Heitsch, Laura; Kauwe, John; Goate, Alison; Piccio, Laura; Cruchaga, Carlos
2016-01-01
Genome-wide association studies of 146 plasma protein levels in 818 individuals revealed 56 genome-wide significant associations (28 novel) with 47 analytes. Loci associated with plasma levels of 39 proteins tested have been previously associated with various complex traits such as heart disease, inflammatory bowel disease, Type 2 diabetes, and multiple sclerosis. These data suggest that these plasma protein levels may constitute informative endophenotypes for these complex traits. We found three potential pleiotropic genes: ABO for plasma SELE and ACE levels, FUT2 for CA19-9 and CEA plasma levels, and APOE for ApoE and CRP levels. We also found multiple independent signals in loci associated with plasma levels of ApoH, CA19-9, FetuinA, IL6r, and LPa. Our study highlights the power of biological traits for genetic studies to identify genetic variants influencing clinically relevant traits, potential pleiotropic effects, and complex disease associations in the same locus.
Analytical study of the effects of wind tunnel turbulence on turbofan rotor noise
NASA Astrophysics Data System (ADS)
Gliebe, P. R.
1980-06-01
An analytical study of the effects of wind tunnel turbulence on turbofan rotor noise was carried out to evaluate the effectiveness of the NASA Ames 40 by 80-foot wind tunnel in simulating flight levels of fan noise. A previously developed theory for predicting rotor/turbulence interaction noise, refined and extended to include first-order effects of inlet turbulence anisotropy, was employed to carry out a parametric study of the effects of fan size, blade number, and operating line for outdoor test stand, NASA Ames wind tunnel, and flight inlet turbulence conditions. A major result of this study is that although wind tunnel rotor/turbulence noise levels are not as low as flight levels, they are substantially lower than the outdoor test stand levels and do not mask other sources of fan noise.
Lin, Xiang-Yun; Wu, Ling-Ling; Pan, Zhong-Qin; Shi, Chuan-Guo; Bao, Ning; Gu, Hai-Ying
2015-04-01
Herein we utilized the filter paper to physically trap red blood cells (RBC) to observe the breathing process of red blood cells based on the permeability of the filter paper. By integrating double-sided conductive carbon tape as the working electrodes, the device could be applied to monitor electrochemical responses of RBC for up to hundreds of minutes. The differential pulse voltammetry (DPV) peak currents increased under oxygen while decreased under nitrogen, indicating that RBC could take in and release oxygen. Further studies demonstrated that the RBC suspension could more effectively take in oxygen than the solution of hemoglobin and the supernatant of RBC, suggesting the natural advantage of RBC on oxygen transportation. This study implied that simple paper-based analytical devices might be effectively applied in the study of gas-participating reactions and biochemical detections.
Optimization of the Pressurized Logistics Module - A Space Station Freedom analytical study
NASA Technical Reports Server (NTRS)
Scallan, J. M.
1991-01-01
The analysis for determining the optimum cylindrical length of the Space Station Freedom (SSF) Pressurized Logistics Module, whose task is to transport the SSF pressurized cargo via the NSTS Shuttle Orbiter, is described. The major factors considered include the NSTS net launch lift capability, the pressurized cargo requirements, and the mass properties of the module structures, mechanisms, and subsystems.
Analytical methodologies for metallomics studies of antitumor Pt-containing drugs.
Esteban-Fernández, Diego; Moreno-Gordaliza, Estefanía; Cañas, Benito; Palacios, María Antonia; Gómez-Gómez, María Milagros
2010-01-01
Pt-containing drugs are nowadays essential components in cancer chemotherapy. However, drug resistance and side effects limit the efficiency of the treatments. In order to improve the response to Pt-based drugs, different administration strategies or new Pt-compounds have been developed with little success. The reason for this failure could be that the mechanism of action of these drugs is not completely understood. In this way, metallomics studies may contribute to clarify the interactions of Pt-containing drugs within the organism. This review is mainly focused on the role of Analytical Chemistry on the study of the interactions between Pt-based drugs and biomolecules. A summary of the analytical techniques and the most common sample treatment procedures currently used in metallomics studies of these drugs is presented. Both are of paramount importance to study these complex samples preserving the drug-biomolecule interaction. Separation and detection techniques must be carefully selected in order to achieve the intended goals. The use of multidimensional hyphenated techniques is usually necessary for a better understanding of the Pt-based drugs interactions in the organism. An overview of Pt-drugs biological interactions is presented, considering the different sample matrices and the drugs course through the organism. Samples analysed in the included studies are blood, urine, cell cytosol, DNA as well as the drugs themselves and their derivatives. However, most of these works are based on in vitro experiments or incubations of standards, leading in some cases to contradictory results depending on the experimental conditions used. Though in vivo experiments represent a great challenge due to the high complexity and the low concentrations of the Pt-adducts in real samples, these studies must be undertaken to get a deeper understanding of the real interactions concerning Pt-containing drugs.
Self-Efficacy and Interest: Experimental Studies of Optimal Incompetence.
ERIC Educational Resources Information Center
Silvia, Paul J.
2003-01-01
To test the optimal incompetence hypothesis (high self-efficacy lowers task interest), 30 subjects rated interest, perceived difficulty, and confidence of success in different tasks. In study 2, 33 subjects completed a dart-game task in easy, moderate, and difficult conditions. In both, interest was a quadratic function of self-efficacy,…
Study of genetic direct search algorithms for function optimization
NASA Technical Reports Server (NTRS)
Zeigler, B. P.
1974-01-01
The results are presented of a study to determine the performance of genetic direct search algorithms in solving function optimization problems arising in the optimal and adaptive control areas. The findings indicate that: (1) genetic algorithms can outperform standard algorithms in multimodal and/or noisy optimization situations, but suffer from lack of gradient exploitation facilities when gradient information can be utilized to guide the search. (2) For large populations, or low dimensional function spaces, mutation is a sufficient operator. However for small populations or high dimensional functions, crossover applied in about equal frequency with mutation is an optimum combination. (3) Complexity, in terms of storage space and running time, is significantly increased when population size is increased or the inversion operator, or the second level adaptation routine is added to the basic structure.
Optimization in generalized linear models: A case study
NASA Astrophysics Data System (ADS)
Silva, Eliana Costa e.; Correia, Aldina; Lopes, Isabel Cristina
2016-06-01
The maximum likelihood method is usually chosen to estimate the regression parameters of Generalized Linear Models (GLM) and also for hypothesis testing and goodness of fit tests. The classical method for estimating GLM parameters is the Fisher scores. In this work we propose to compute the estimates of the parameters with two alternative methods: a derivative-based optimization method, namely the BFGS method which is one of the most popular of the quasi-Newton algorithms, and the PSwarm derivative-free optimization method that combines features of a pattern search optimization method with a global Particle Swarm scheme. As a case study we use a dataset of biological parameters (phytoplankton) and chemical and environmental parameters of the water column of a Portuguese reservoir. The results show that, for this dataset, BFGS and PSwarm methods provided a better fit, than Fisher scores method, and can be good alternatives for finding the estimates for the parameters of a GLM.
An analytical study of PPP-RTK corrections: precision, correlation and user-impact
NASA Astrophysics Data System (ADS)
Khodabandeh, A.; Teunissen, P. J. G.
2015-11-01
PPP-RTK extends the PPP concept by providing single-receiver users, next to orbits and clocks, also information about the satellite phase and code biases, thus enabling single-receiver ambiguity resolution. It is the goal of the present contribution to provide an analytical study of the quality of the PPP-RTK corrections as well as of their impact on the user ambiguity resolution performance. We consider the geometry-free and the geometry-based network derived corrections, as well as the impact of network ambiguity resolution on these corrections. Next to the insight that is provided by the analytical solutions, the closed form expressions of the variance matrices also demonstrate how the corrections depend on network parameters such as number of epochs, number of stations, number of satellites, and number of frequencies. As a result we are able to describe in a qualitative sense how the user ambiguity resolution performance is driven by the data from the different network scenarios.
Visual analytics for multimodal social network analysis: a design study with social scientists.
Ghani, Sohaib; Kwon, Bum Chul; Lee, Seungyoon; Yi, Ji Soo; Elmqvist, Niklas
2013-12-01
Social network analysis (SNA) is becoming increasingly concerned not only with actors and their relations, but also with distinguishing between different types of such entities. For example, social scientists may want to investigate asymmetric relations in organizations with strict chains of command, or incorporate non-actors such as conferences and projects when analyzing coauthorship patterns. Multimodal social networks are those where actors and relations belong to different types, or modes, and multimodal social network analysis (mSNA) is accordingly SNA for such networks. In this paper, we present a design study that we conducted with several social scientist collaborators on how to support mSNA using visual analytics tools. Based on an openended, formative design process, we devised a visual representation called parallel node-link bands (PNLBs) that splits modes into separate bands and renders connections between adjacent ones, similar to the list view in Jigsaw. We then used the tool in a qualitative evaluation involving five social scientists whose feedback informed a second design phase that incorporated additional network metrics. Finally, we conducted a second qualitative evaluation with our social scientist collaborators that provided further insights on the utility of the PNLBs representation and the potential of visual analytics for mSNA. PMID:24051769
Study of Gaussian and Bessel beam propagation using a new analytic approach
NASA Astrophysics Data System (ADS)
Dartora, C. A.; Nobrega, K. Z.
2012-03-01
The main feature of Bessel beams realized in practice is their ability to resist diffractive effects over distances exceeding the usual diffraction length. The theory and experimental demonstration of such waves can be traced back to the seminal work of Durnin and co-workers already in 1987. Despite that fact, to the best of our knowledge, the study of propagation of apertured Bessel beams found no solution in closed analytic form and it often leads to the numerical evaluation of diffraction integrals, which can be very awkward. In the context of paraxial optics, wave propagation in lossless media is described by an equation similar to the non-relativistic Schrödinger equation of quantum mechanics, but replacing the time t in quantum mechanics by the longitudinal coordinate z. Thus, the same mathematical methods can be employed in both cases. Using Bessel functions of the first kind as basis functions in a Hilbert space, here we present a new approach where it is possible to expand the optical wave field in a series, allowing to obtain analytic expressions for the propagation of any given initial field distribution. To demonstrate the robustness of the method two cases were taken into account: Gaussian and zeroth-order Bessel beam propagation.
NASA Technical Reports Server (NTRS)
Cucinotta, Francis A.; Wilson, John W.
1996-01-01
The angular momentum independent statistical decay model is often applied using a Monte-Carlo simulation to describe the decay of prefragment nuclei in heavy ion reactions. This paper presents an analytical approach to the decay problem of nuclei with mass number less than 60, which is important for galactic cosmic ray (GCR) studies. This decay problem of nuclei with mass number less than 60 incorporates well-known levels of the lightest nuclei (A less than 11) to improve convergence and accuracy. A sensitivity study of the model level density function is used to determine the impact on mass and charge distributions in nuclear fragmentation. This angular momentum independent statistical decay model also describes the momentum and energy distribution of emitted particles (n, p, d, t, h, and a) from a prefragment nucleus.
Wang, Taowei David; Wongsuphasawat, Krist; Plaisant, Catherine; Shneiderman, Ben
2011-10-01
Current electronic health record (EHR) systems facilitate the storage, retrieval, persistence, and sharing of patient data. However, the way physicians interact with EHRs has not changed much. More specifically, support for temporal analysis of a large number of EHRs has been lacking. A number of information visualization techniques have been proposed to alleviate this problem. Unfortunately, due to their limited application to a single case study, the results are often difficult to generalize across medical scenarios. We present the usage data of Lifelines2 (Wang et al. 2008), our information visualization system, and user comments, both collected over eight different medical case studies. We generalize our experience into a visual analytics process model for multiple EHRs. Based on our analysis, we make seven design recommendations to information visualization tools to explore EHR systems.
Analytical study of X-class flares released during year 2014
NASA Astrophysics Data System (ADS)
AbdelHady, Ahmed
2016-07-01
Eruptive X-class flares occurred during year 2014 with high energetic particles are stronger than which occurred during the mean peak of solar cycle 24. We notes that during the last 5 solar cycles a new peak has appeared releasing high energetic particles and X-class solar flares which are called the secondary peak or the double peak of solar cycle. The aim of this analytical study is to follow the X-class flares released study how can be predict it according to data analysis. Furthermore, the causes of the release of these eruptive storms have been discussed for the period of year 2014, during the double peak of the solar cycle 24.
Semi-analytical fluid study of the laser wake field excitation in the strong intensity regime
NASA Astrophysics Data System (ADS)
Jovanović, D.; Fedele, R.; Belić, M.; De Nicola, S.
2016-09-01
We present an analytical and numerical study of the interaction of a multi-petawatt, pancake-shaped laser pulse with an unmagnetized plasma. The study has been performed in the ultrarelativistic regime of electron jitter velocities, in which the plasma electrons are almost completely expelled from the pulse region. The calculations are applied to a laser wake field acceleration scheme with specifications that may be available in the next generation of Ti:Sa lasers and with the use of recently developed pulse compression techniques. A set of novel nonlinear equations is derived using a three-timescale description, with an intermediate timescale associated with the nonlinear phase of the electromagnetic wave and with the spatial bending of its wave front. They describe, on an equal footing, both the strong and the moderate laser intensity regimes, pertinent to the core and to the edges of the pulse.
Use of stable isotopes of selenium in human metabolic studies: development of analytical methodology
Janghorbani, M.; Ting, B.T.; Young, V.R.
1981-12-01
Use of stable isotopes of selenium in relation to enrichment of diets for studies of selenium absorption and metabolism in human subjects is discussed. A method based on radiochemical neutron activation analysis is described which allows accurate measurement of stable isotopes 74Se, 76Se, and 80Se in matrices (feces, plasma, red blood cells, and urine) of interest in metabolic studies. We show that these isotopes can routinely be measured with analytical precision and accuracy of 10% in samples of available size. This precision and accuracy is satisfactory for conduct of many nutritional experiments concerned with gastrointestinal absorption, plasma and red cell selenium turnover, and urinary excretion of the element, using an oral dose of 74Se. Original, experimental data are presented to illustrate the degree of enrichment of 74Se in feces, plasma, and urine after a single oral ingestion of 50 micrograms of the isotope with a breakfast meal in healthy young men.
NASA Astrophysics Data System (ADS)
Afzali-Far, Behrouz; Andersson, Anette; Nilsson, Kristina; Lidström, Per
2015-09-01
Consideration of strut inertia can have significant influence on the modal behavior of a Gough-Stewart Platform (GSP). However, in the literature, the strut inertia has not yet been taken into account in its vibration study with a parametric approach. In this paper, we present a fully parametric approach to formulate the damped vibrations of GSPs taking into account the strut masses and moments of inertia for symmetric configurations. For the first time, a combined 6×6 equivalent inertia matrix (mass matrix), including both the inertia properties of the platform and the struts, is formulated parametrically. Subsequently, the eigenvectors and the damped eigenfrequencies are also parametrically developed in the Cartesian space. Furthermore, the conditions for the decoupled vibrations and the effect of strut inertia on these conditions are analytically investigated. With the aid of a reference GSP, the influence of the strut inertia on its modal behavior is systematically investigated. Accordingly, it is concluded that the parametric equations established in this paper can be directly employed in the analysis, optimization and control of GSPs in any application.
Serrano-Gallardo, Pilar; Martínez-Marcos, Mercedes; Espejo-Matorrales, Flora; Arakawa, Tiemi; Magnabosco, Gabriela Tavares; Pinto, Ione Carvalho
2016-01-01
ABSTRACT Objective: to identify the students' perception about the quality of clinical placements and asses the influence of the different tutoring processes in clinical learning. Methods: analytical cross-sectional study on second and third year nursing students (n=122) about clinical learning in primary health care. The Clinical Placement Evaluation Tool and a synthetic index of attitudes and skills were computed to give scores to the clinical learning (scale 0-10). Univariate, bivariate and multivariate (multiple linear regression) analyses were performed. Results: the response rate was 91.8%. The most commonly identified tutoring process was "preceptor-professor" (45.2%). The clinical placement was assessed as "optimal" by 55.1%, relationship with team-preceptor was considered good by 80.4% of the cases and the average grade for clinical learning was 7.89. The multiple linear regression model with more explanatory capacity included the variables "Academic year" (beta coefficient = 1.042 for third-year students), "Primary Health Care Area (PHC)" (beta coefficient = 0.308 for Area B) and "Clinical placement perception" (beta coefficient = - 0.204 for a suboptimal perception). Conclusions: timeframe within the academic program, location and clinical placement perception were associated with students' clinical learning. Students' perceptions of setting quality were positive and a good team-preceptor relationship is a matter of relevance. PMID:27627124
Analytical and numerical studies of photo-injected charge transport in molecularly-doped polymers
NASA Astrophysics Data System (ADS)
Roy Chowdhury, Amrita
The mobility of photo-injected charge carriers in molecularly-doped polymers (MDPs) exhibits a commonly observed, and nearly universal Poole-Frenkel field dependence, mu exp√(beta0E), that has been shown to arise from the correlated Gaussian energy distribution of transport sites encountered by charges undergoing hopping transport through the material. Analytical and numerical studies of photo-injected charge transport in these materials are presented here with an attempt to understand how specific features of the various models developed to describe these systems depend on the microscopic parameters that define them. Specifically, previously published time-of-flight mobility data for the molecularly doped polymer 30% DEH:PC (polycarbonate doped with 30 wt.% aromatic hydrazone DEH) is compared with direct analytical and numerical predictions of five disorder-based models, the Gaussian disorder model (GDM) of Bassler, and four correlated disorder models introduced by Novikov, et al., and by Parris, et al. In these numerical studies, disorder parameters describing each model were varied from reasonable starting conditions, in order to give the best overall fit. The uncorrelated GDM describes the Poole-Frenkel field dependence of the mobility only at very high fields, but fails for fields lower than about 64 V/mum. The correlated disorder models with small amounts of geometrical disorder do a good over-all job of reproducing a robust Poole-Frenkel field dependence, with correlated disorder theories that employ polaron transition rates showing qualitatively better agreement with experiment than those that employ Miller-Abrahams rates. In a separate study, the heuristic treatment of spatial or geometric disorder incorporated in existing theories is critiqued, and a randomly-diluted lattice gas model is developed to describe the spatial disorder of the transport sites in a more realistic way.
NASA Astrophysics Data System (ADS)
Zhang, Zhizeng; Zhao, Zhao; Li, Yongtao
2016-06-01
This paper attempts to verify the correctness of the analytical displacement solution in transversely isotropic rock mass, and to determine the scope of its application. The analytical displacement solution of a circular tunnel in transversely isotropic rock mass was derived firstly. The analytical solution was compared with the numerical solution, which was carried out by FLAC3D software. The results show that the expression of the analytical displacement solution is correct, and the allowable engineering range is that the dip angle is less than 15 degrees.
Moretto Galazzi, Rodrigo; Arruda, Marco Aurélio Zezzi
2013-12-15
The present work describes a metallic tube as hydride atomizer for atomic absorption spectrometry. Its performance is evaluated through tin determination, and the accuracy of the method assessed through the analysis of sediment and water samples. Some chemical parameters (referring to the generation of the hydride) such as acid, NaOH and THB concentrations, as well as physical parameters (referring to the transport of the hydride) such as carrier, acetylene, air flow-rates, flame composition, coil length, tube hole area, among others, are evaluated for optimization of the method. Scanning electron microscopy is used for evaluating morphological parameters in both new and used (after 150 h) tube atomizers. The method presents linear Sn concentration from 50 to 1000 µg L(-1) (r>0.9995; n=3) and the analytical frequency of ca. 40 h(-1). The limit of detection (LOD) is 7.1 µg L(-1) and the precision, expressed as RSD is less than 4% (200 µg L(-1); n=10). The accuracy is evaluated through reference materials, and the results are similar at 95% confidence level according to the t-test.
Extended analytical study of the free-wing/free-trimmer concept
NASA Technical Reports Server (NTRS)
Porter, R. F.; Hall, D. W.; Vergara, R. D.
1979-01-01
The free wing/free trimmer concept was analytically studied in order to: (1) compare the fore and aft trimmer configurations on the basis of equal lift capability, rather than equal area; (2) assess the influence of tip mounted aft trimmers, both free and fixed, on the lateral directional modes and turbulence responses; (3) examine the feasibility of using differential tip mounted trimmer deflection for lateral control; (4) determine the effects of independent fuselage attitude on the lateral directional behavior; and (5) estimate the influence of wing sweep on dynamic behavior and structural weight. Results indicate that the forward trimmer concept is feasible with the reduced size examined, but it remains inferior to the aft trimmer in every respect except structural weight. Differential motion of the aft trimmer is found to provide powerful lateral control; while the effect of fuselage deck angle is a reduction of the dutch roll damping ratio for nose-down attitudes.
Heuristic and analytic processes in reasoning: an event-related potential study of belief bias.
Banks, Adrian P; Hope, Christopher
2014-03-01
Human reasoning involves both heuristic and analytic processes. This study of belief bias in relational reasoning investigated whether the two processes occur serially or in parallel. Participants evaluated the validity of problems in which the conclusions were either logically valid or invalid and either believable or unbelievable. Problems in which the conclusions presented a conflict between the logically valid response and the believable response elicited a more positive P3 than problems in which there was no conflict. This shows that P3 is influenced by the interaction of belief and logic rather than either of these factors on its own. These findings indicate that belief and logic influence reasoning at the same time, supporting models in which belief-based and logical evaluations occur in parallel but not theories in which belief-based heuristic evaluations precede logical analysis.
Focused Experimental and Analytical Studies of the RBCC Rocket-Ejector
NASA Technical Reports Server (NTRS)
Lehman, M.; Pal, S.; Schwes, D.; Chen, J. D.; Santoro, R. J.
1999-01-01
The rocket-ejector mode of a Rocket Based Combined Cycle Engine (RBCC) was studied through a joint experimental/analytical approach. A two-dimensional variable geometry rocket-ejector system with enhanced optical access was designed and fabricated for experimentation. The rocket-ejector system utilizes a single two-dimensional gaseous oxygen/gaseous hydrogen rocket as the ejector. To gain a systematic understanding of the rocket ejector's internal fluid mechanic/combustion phenomena, experiments were conducted with both direct-connect and sea-level static configurations for a range of rocket operating conditions Overall system performance was obtained through Global measurements of wall static pressure profiles, heat flux profiles and engine thrust, whereas detailed mixing and combustion information was obtained through Raman spectroscopy measurements of major species (gaseous oxygen, hydrogen. nitrogen and water vapor). These experimental efforts were complemented by Computational Fluid Dynamic (CFD) flowfield analyses.
Analytical Ultracentrifugation as a Tool to Study Nonspecific Protein–DNA Interactions
Yang, Teng-Chieh; Catalano, Carlos Enrique; Maluf, Nasib Karl
2016-01-01
Analytical ultracentrifugation (AUC) is a powerful tool that can provide thermodynamic information on associating systems. Here, we discuss how to use the two fundamental AUC applications, sedimentation velocity (SV), and sedimentation equilibrium (SE), to study nonspecific protein–nucleic acid interactions, with a special emphasis on how to analyze the experimental data to extract thermodynamic information. We discuss three specific applications of this approach: (i) determination of nonspecific binding stoichiometry of E. coli integration host factor protein to dsDNA, (ii) characterization of nonspecific binding properties of Adenoviral IVa2 protein to dsDNA using SE-AUC, and (iii) analysis of the competition between specific and nonspecific DNA-binding interactions observed for E. coli integration host factor protein assembly on dsDNA. These approaches provide powerful tools that allow thermodynamic interrogation and thus a mechanistic understanding of how proteins bind nucleic acids by both specific and nonspecific interactions. PMID:26412658
An Analytical Study of Fuzzy Control of a Flexible Rod Mechanism
NASA Astrophysics Data System (ADS)
Beale, D.; Lee, S. W.; Boghiu, D.
1998-02-01
The non-linear nature of very high speed, flexible rod mechanisms has been previously confirmed, both experimentally and analytically in reference [1]. Therefore, effective control system design for flexible mechanisms operating at very high speeds must consider the non-linearities when designing a controller for very high speeds. Active control via fuzzy logic is assessed as means to suppress the elastic transverse bending vibration of a flexible rod of a slider crank mechanism. Several pairs of piezoelectric elements are used to provide the control action. Sensor output of deflection is fed to the fuzzy controller, which determines the voltage input to the actuators. A three mode approximation is used in the simulation study. Computer simulation shows that fuzzy control can be used to suppress bending vibrations at high speeds, and even at speeds where the uncontrolled response would be unstable.
NASA Astrophysics Data System (ADS)
Bhatti, M. M.; Zeeshan, A.
2016-06-01
In this paper, effects of variable viscosity with heat transfer on solid particle motion of dusty Jeffrey fluid model through a planar channel has been examined. The governing flow problem for fluid phase and dusty phase is formulated with the help of momentum and energy equation. The resulting coupled ordinary differential equations have been solved analytically and closed form solutions are presented. The influence of all the physical parameters are sketched for velocity profile, pressure rise and temperature profile. Numerical computation is used to evaluate the expression for pressure rise. The present analysis is also presented for Newtonian fluid by taking λ1 → 0 as a special case of our study. It is found that due to the influence of variable viscosity, the fluid velocity changes in the center of the channel and shows opposite behavior near the walls. It is also found that temperature profile increases for larger values of Prandtl number (Pr) and Eckert number (Ec).
An analytical electron microscope study of airborne industrial particles in Sosnowiec, Poland
NASA Astrophysics Data System (ADS)
Rietmeijer, Frans J. M.; Janeczek, Janusz
The types and the relative amounts of airborne particles in the city of Sosnowiec (Poland) during 21-22 June, 1994 were identified by analytical electron microscope analyses. They are mostly aspherical angular Al-bearing silica particles (0.1-5.15 μm) and clusters thereof. Carbonaceous particles form sheets of soluble volatile-rich materials (0.3-33.9 μm) and rare soot. Numerous nanometer-sized Al-bearing silica grains and salt minerals are associated with the larger particles. They resulted from inefficient combustion of low-grade coals by the local industries whereby the silica particles are coal impurities that survived combustion. The total particle emission was constant during a 24 h period but silica shards dominated the nighttime emission while carbonaceous particles abounded during the daytime. This study showed that tropospheric particles in regions dominated by inefficient coal combustion are fundamentally different from typical coal fly ash spheres.
Rajashekhara, N; Vasanth, P; Kumar, D Vijaya
2012-07-01
Prasarani is one of the drugs used in Vata Rogas such as Amavata, Avabahuka, etc. Among the different source plants of Prasarani, the plant Merremia tridentata Haller.f. is mostly used in South India and the plant Paderia foetida Linn. in North India, hence taken in the present work for comparative analytical study. It was observed that there is a common constituent (having 350 mm absorbance maxima) present in both the drug samples indicating that both works on a similar disease. It was also found that the whole plant powder sample of P. foetida has more number of constituents than that of M. tridentata which indicates P. foetida may have a better efficacy than M. tridentata. PMID:23723657
Le Brech, Yann; Ghislain, Thierry; Leclerc, Sébastien; Bouroukba, Mohammed; Delmotte, Luc; Brosse, Nicolas; Snape, Colin; Chaimbault, Patrick; Dufour, Anthony
2016-04-21
Complementary analytical methods have been used to study the effect of potassium on the pyrolysis mechanisms of cellulose and lignocellulosic biomasses. Thermogravimetry, calorimetry, high-temperature (1) H NMR spectroscopy (in situ and real-time analysis of the fluid phase formed during pyrolysis), and water extraction of quenched char followed by size-exclusion chromatography coupled with mass spectrometry have been combined. Potassium impregnated in cellulose suppresses the formation of anhydrosugars, reduces the formation of mobile protons, and gives rise to a mainly exothermic signal. The evolution of mobile protons formed from K-impregnated cellulose has a very similar pattern to the evolution of the mass loss rate. This methodology has been also applied to analyze miscanthus, demineralized miscanthus, miscanthus re-impregnated with potassium after demineralization, raw oak, and Douglas fir. Hydrogen mobility and transfer are of high importance in the mechanisms of biomass pyrolysis. PMID:26990591
Ground Based Studies of Thermocapillary Flows in Levitated Drops: Analytical Part
NASA Technical Reports Server (NTRS)
Sadhal, S. S.; Trinh, Eugene H.
1997-01-01
The main objectives of the analytical part of this investigation are to study the fluid flow phenomena together with the thermal effects on drops levitated in an acoustic field. To a large extent, experimentation on ground requires a strong acoustic field that has a significant interference with other thermal-fluid effects. While most of the work has been directed towards particles in strong acoustic fields to overcome gravity, some results for microgravity have been obtained. One of the objectives was to obtain the thermocapillary flow in a spot-heated drop, and set up a model for the prediction of thermophysical properties. In addition, for acoustically levitated particles, a clear understanding of the underlying fluid mechanics was required. Also, the interaction of acoustics with steady and pulsating thermal stimuli was required to be analyzed. The experimental part of the work was funded through JPL, and has been reported separately.
Lewis, D.W. . Dept. of Geology); McConchie, D.M. . Centre for Coastal Management)
1994-01-01
Both a self instruction manual and a cookbook'' guide to field and laboratory analytical procedures, this book provides an essential reference for non-specialists. With a minimum of mathematics and virtually no theory, it introduces practitioners to easy, inexpensive options for sample collection and preparation, data acquisition, analytic protocols, result interpretation and verification techniques. This step-by-step guide considers the advantages and limitations of different procedures, discusses safety and troubleshooting, and explains support skills like mapping, photography and report writing. It also offers managers, off-site engineers and others using sediments data a quick course in commissioning studies and making the most of the reports. This manual will answer the growing needs of practitioners in the field, either alone or accompanied by Practical Sedimentology, which surveys the science of sedimentology and provides a basic overview of the principles behind the applications.
NASA Astrophysics Data System (ADS)
Gao, Jianxin; Cheng, Li
2003-10-01
Active noise control has recently been used to increase the sound transmission loss of double wall structures. Vibration energy transmission through a double-plates system is investigated experimentally and analytically in this paper. Novel high performance actuators which use two curved THUNDER actuators as active driving components are developed and mounted between the two plates to control the energy transmission in the double-plates system. The Rayleigh-Ritz method and eigenfunction expansion theorem are used to resolve arbitrary boundary conditions of plates, and the feedforward control strategy is employed in this paper. The time average power transmission between the source, actuators and receiver plate are discussed and utilized as a cost function to obtain optimal control. The optimal control voltages for actuators are obtained by minimizing the cost function. A double-plates system connected by four actuators is set up experimentally in order to verify the models and formulations by comparing with analytical results. The analytical and experimental data show that the new actuator exhibits excellent performance on active control of power transmission.
Glyphosate and AMPA in the estuaries of the Baltic Sea method optimization and field study.
Skeff, Wael; Neumann, Christine; Schulz-Bull, Detlef E
2015-11-15
Water samples from ten German Baltic estuaries were collected in 2012 in order to study the presence of the herbicide glyphosate, its primary metabolite AMPA and their potential transport to the marine environment. For the analyses an LC-MS/MS based analytical method after derivatization with FMOC-Cl was optimized and validated for marine water samples. All investigated estuarine stations were contaminated with AMPA and nine of them also with glyphosate. Concentration ranges observed were 28 to 1690ng/L and 45 to 4156ng/L for glyphosate and AMPA, respectively with strong spatial and temporal fluctuations. Both contaminants were found at inbound sampling sites in the stream Muehlenfliess and concentrations decreased along the salinity gradient to the estuaries of the Baltic Sea. The data obtained in this study clearly depict the transport of glyphosate and AMPA to the Baltic Sea. Hence, detailed fate and risk assessment for both contaminants in marine environments are required.
Action Video Game Training for Healthy Adults: A Meta-Analytic Study
Wang, Ping; Liu, Han-Hui; Zhu, Xing-Ting; Meng, Tian; Li, Hui-Jie; Zuo, Xi-Nian
2016-01-01
Action video game (AVG) has attracted increasing attention from both the public and from researchers. More and more studies found video game training improved a variety of cognitive functions. However, it remains controversial whether healthy adults can benefit from AVG training, and whether young and older adults benefit similarly from AVG training. In the present study, we aimed to quantitatively assess the AVG training effect on the cognitive ability of adults and to compare the training effects on young and older adults by conducting a meta-analysis on previous findings. We systematically searched video game training studies published between January 1986 and July 2015. Twenty studies were included in the present meta-analysis, for a total of 313 participants included in the training group and 323 participants in the control group. The results demonstrate that healthy adults achieve moderate benefit from AVG training in overall cognitive ability and moderate to small benefit in specific cognitive domains. In contrast, young adults gain more benefits from AVG training than older adults in both overall cognition and specific cognitive domains. Age, education, and some methodological factors, such as the session duration, session number, total training duration, and control group type, modulated the training effects. These meta-analytic findings provide evidence that AVG training may serve as an efficient way to improve the cognitive performance of healthy adults. We also discussed several directions for future AVG training studies. PMID:27378996
Action Video Game Training for Healthy Adults: A Meta-Analytic Study.
Wang, Ping; Liu, Han-Hui; Zhu, Xing-Ting; Meng, Tian; Li, Hui-Jie; Zuo, Xi-Nian
2016-01-01
Action video game (AVG) has attracted increasing attention from both the public and from researchers. More and more studies found video game training improved a variety of cognitive functions. However, it remains controversial whether healthy adults can benefit from AVG training, and whether young and older adults benefit similarly from AVG training. In the present study, we aimed to quantitatively assess the AVG training effect on the cognitive ability of adults and to compare the training effects on young and older adults by conducting a meta-analysis on previous findings. We systematically searched video game training studies published between January 1986 and July 2015. Twenty studies were included in the present meta-analysis, for a total of 313 participants included in the training group and 323 participants in the control group. The results demonstrate that healthy adults achieve moderate benefit from AVG training in overall cognitive ability and moderate to small benefit in specific cognitive domains. In contrast, young adults gain more benefits from AVG training than older adults in both overall cognition and specific cognitive domains. Age, education, and some methodological factors, such as the session duration, session number, total training duration, and control group type, modulated the training effects. These meta-analytic findings provide evidence that AVG training may serve as an efficient way to improve the cognitive performance of healthy adults. We also discussed several directions for future AVG training studies.
Action Video Game Training for Healthy Adults: A Meta-Analytic Study.
Wang, Ping; Liu, Han-Hui; Zhu, Xing-Ting; Meng, Tian; Li, Hui-Jie; Zuo, Xi-Nian
2016-01-01
Action video game (AVG) has attracted increasing attention from both the public and from researchers. More and more studies found video game training improved a variety of cognitive functions. However, it remains controversial whether healthy adults can benefit from AVG training, and whether young and older adults benefit similarly from AVG training. In the present study, we aimed to quantitatively assess the AVG training effect on the cognitive ability of adults and to compare the training effects on young and older adults by conducting a meta-analysis on previous findings. We systematically searched video game training studies published between January 1986 and July 2015. Twenty studies were included in the present meta-analysis, for a total of 313 participants included in the training group and 323 participants in the control group. The results demonstrate that healthy adults achieve moderate benefit from AVG training in overall cognitive ability and moderate to small benefit in specific cognitive domains. In contrast, young adults gain more benefits from AVG training than older adults in both overall cognition and specific cognitive domains. Age, education, and some methodological factors, such as the session duration, session number, total training duration, and control group type, modulated the training effects. These meta-analytic findings provide evidence that AVG training may serve as an efficient way to improve the cognitive performance of healthy adults. We also discussed several directions for future AVG training studies. PMID:27378996
NASA Astrophysics Data System (ADS)
Serra, Catarina; Simões, Nuno; Tadeu, António
2015-05-01
This paper compares experimental and heat transfer modeling results for thermography applications in building elements. Over the years most building envelope inspections using infrared thermography (IRT) have been focused on qualitative analysis using mostly passive thermography techniques. However, increased need for the monitorization and assessment of the energy performance and thermal behavior of buildings, along with ongoing structural safety concerns, has raised interest in quantitative studies and active IRT applications in buildings. Numerous other fields have benefited from developments in defect detection studies and from countless non-destructive testing applications. Pulse phase thermography, in which phase images are studied (instead of temperature images) using a long heating pulse have been proposed to be the most effective for Civil Engineering applications. However, the particular characteristics of building elements and materials, along with the complex nature of heat transfer phenomena, demand specific experimental procedures and processing techniques. In this paper, analytical solutions to simulate heat transfer in the frequency domain in multi-layered media are used to compute thermal wave phase results. These are compared to experimental IRT phase analysis results of experiments performed on test specimens simulating building elements with embedded defects. Crucial test parameters such as test duration and defect characteristics are changed and their influence is studied. In this way, this paper contributes to the understanding of building envelope thermal patterns using active IRT in defect detection studies and to the definition of test parameters.
Optimization Shield Materials Trade Study for Lunar/Gateway Mission
NASA Technical Reports Server (NTRS)
Tripathi, R. K.; Wilson, J. W.; Cucinotta, F. A.; Anderson, B. M.; Simonsen, L. C.
2002-01-01
The great cost of added radiation shielding is a potential limiting factor in many deep space missions. For this enabling technology, we are developing tools for optimized shield design over multi-segmented missions involving multiple work and living areas in the transport and duty phase of various space missions. The total shield mass over all pieces of equipment and habitats is optimized subject to career dose and dose rate constraints. Preliminary studies of deep space missions indicate that for long duration space missions, improved shield materials will be required. The details of this new method and its impact on space missions and other technologies will be discussed. This study will provide a vital tool for evaluating Gateway designs in their usage context. Providing protection against the hazards of space radiation is one of the challenges to the Gateway infrastructure designs. We will use the mission optimization software to scope the impact of Gateway operations on human exposures and the effectiveness of alternate shielding materials on Gateway infrastructure designs. It is being proposed to use Moon and the Lagrange points as the hub for deep space missions. This study will provide a guide to the effectiveness of multifunctional materials in preparation to more detailed geometry studies in progress.
ERIC Educational Resources Information Center
Budsankom, Prayoonsri; Sawangboon, Tatsirin; Damrongpanit, Suntorapot; Chuensirimongkol, Jariya
2015-01-01
The purpose of the research is to develop and identify the validity of factors affecting higher order thinking skills (HOTS) of students. The thinking skills can be divided into three types: analytical, critical, and creative thinking. This analysis is done by applying the meta-analytic structural equation modeling (MASEM) based on a database of…
Factors Influencing Beliefs for Adoption of a Learning Analytics Tool: An Empirical Study
ERIC Educational Resources Information Center
Ali, Liaqat; Asadi, Mohsen; Gasevic, Dragan; Jovanovic, Jelena; Hatala, Marek
2013-01-01
Present research and development offer various learning analytics tools providing insights into different aspects of learning processes. Adoption of a specific tool for practice is based on how its learning analytics are perceived by educators to support their pedagogical and organizational goals. In this paper, we propose and empirically validate…
ERIC Educational Resources Information Center
Ifenthaler, Dirk; Widanapathirana, Chathuranga
2014-01-01
Interest in collecting and mining large sets of educational data on student background and performance to conduct research on learning and instruction has developed as an area generally referred to as learning analytics. Higher education leaders are recognizing the value of learning analytics for improving not only learning and teaching but also…
Cook, Joseph; Jeuland, Marc; Maskery, Brian; Lauria, Donald; Sur, Dipika; Clemens, John; Whittington, Dale
2009-01-01
Although it is well known that vaccines against many infectious diseases confer positive economic externalities via indirect protection, analysts have typically ignored possible herd protection effects in policy analyses of vaccination programs. Despite a growing literature on the economic theory of vaccine externalities and several innovative mathematical modeling approaches, there have been almost no empirical applications. The first objective of the paper is to develop a transparent, accessible economic framework for assessing the private and social economic benefits of vaccination. We also describe how stated preference studies (for example, contingent valuation and choice modeling) can be useful sources of economic data for this analytic framework. We demonstrate socially optimal policies using a graphical approach, starting with a standard textbook depiction of Pigouvian subsidies applied to herd protection from vaccination programs. We also describe nonstandard depictions that highlight some counterintuitive implications of herd protection that we feel are not commonly understood in the applied policy literature. We illustrate the approach using economic and epidemiological data from two neighborhoods in Kolkata, India. We use recently published epidemiological data on the indirect effects of cholera vaccination in Matlab, Bangladesh (Ali et al., 2005) for fitting a simple mathematical model of how protection changes with vaccine coverage. We use new data on costs and private demand for cholera vaccines in Kolkata, India, and approximate the optimal Pigouvian subsidy. We find that if the optimal subsidy is unknown, selling vaccines at full marginal cost may, under some circumstances, be a preferable second-best option to providing them for free.
Differences in working memory involvement in analytical and creative tasks: an ERP study.
Lavric, A; Forstmeier, S; Rippon, G
2000-06-01
If, as suggested, creative (insight) problem solving is less systematic and employs less planning than analytical problem solving, the former requires substantially less working memory (WM) than the latter. Subjects simultaneously solved problems and counted auditory stimuli (concurrent WM task), in response to which ERPs were recorded. Counting disrupted analytical, but not creative performance. Peak and time-window average P300 were more frontal during analytical problem solving as compared to insight or counting tones only (control). A PCA extracted two factors in the P3 range, one frontal and one broad left-lateralized, which distinguished analytical from creative problem solving. The findings indicate distinct processing pathways for the two types of tasks with more WM involvement in analytical tasks.
An optimization study of the motion table performance.
Hsiao, Y F; Kuo, W M; Chang, Y T; Tarng, Y S
2010-01-01
This paper investigates the optimal selection of processing parameters for motion table performance. The main objective of the mechanism of a one-axis servo motor table is to avoid vibration, thereby reducing experimental error. This experimental controller uses a grey-based Taguchi method to make a quality evaluation of three table characteristics; displacement, arriving time, and torsion. It is shown that the multiple response performance characteristics are greatly improved through this study.
An Analytical Study on Periodically Changing Flow Cells in Groundwater Basins
NASA Astrophysics Data System (ADS)
Jiang, X.; Zhao, K. Y.; Wang, J. Z.; Wan, L.; Wang, H.
2014-12-01
Current understanding on basin-scale groundwater flow is mainly based on Tóth's (1962, 1963) pioneering study, which assumed that water table is a subdued replica of topography and the annual mean water table controls the pattern of groundwater flow. In fact, water table is driven by dynamic forcing and changes with time. This study modifies the conceptual model of basin-scale groundwater flow by taking the fluctuating water-table into account. For both unit basin and complex basin, water table fluctuates throughout the basin cross-section except for at basin valleys. By the method of separation of variables, we derive the analytical solution of hydraulics head and stream function in the unit basin and the complex basin, and discuss the characteristics of the time-dependent flow cells. For the unit basin, the change in amplitude of hydraulic head fluctuation with depth is studied. For the complex basin, the time-dependent distribution of internal stagnation points is discussed. In addition, the relationship between flowing artesian zone and the fluctuating water-table is discussed. The results of the current study enhance our understanding on the transient nature of basin-scale groundwater flow.
OPTIMIZATION STUDY FOR FILL STEM MANUFACTURINGAND PINCH WELD PROCESSING
Korinko, P; Karl Arnold, K
2006-09-06
A statistically designed experiment was conducted as part of a six sigma project for Fill Stem Manufacturing and Pinch Weld Processing. This multi-year/multi-site project has successfully completed a screening study and used those results as inputs to this optimization study. Eleven welds were made using fairly tight current and cycle range. The welds demonstrate increased burst strength, longer closure length, more net displacement, and improved bond rating with increased current. However, excessive melting remains a concern from a processing viewpoint and may cause adverse metallurgical interactions. Therefore, the highest current levels specified cannot be utilized. A Validation Study is proposed for the Defense Programs Inert Facility.
Experimental and Analytical Seismic Studies of a Four-Span Bridge System with Innovative Materials
NASA Astrophysics Data System (ADS)
Cruz Noguez, Carlos Alonso
As part of a multi-university project utilizing the NSF Network for Earthquake Engineering Simulation (NEES), a quarter-scale model of a four-span bridge incorporating plastic hinges with different advanced materials was tested to failure on the three shake table system at the University of Nevada, Reno (UNR). The bridge was the second test model in a series of three 4-span bridges, with the first model being a conventional reinforced-concrete (RC) structure. The purpose of incorporating advanced materials was to improve the seismic performance of the bridge with respect to two damage indicators: (1) column damage and (2) permanent deformations. The goals of the study presented in this document were to (1) evaluate the seismic performance of a 4-span bridge system incorporating SMA/ECC and built-in rubber pad plastic hinges as well as post-tensioned piers, (2) quantify the relative merit of these advanced materials and details compared to each other and to conventional reinforced concrete plastic hinges, (3) determine the influence of abutment-superstructure interaction on the response, (4) examine the ability of available elaborate analytical modeling techniques to model the performance of advanced materials and details, and (5) conduct an extensive parametric study of different variations of the bridge model to study several important issues in bridge earthquake engineering. The bridge model included six columns, each pair of which utilized a different advanced detail at bottom plastic hinges: shape memory alloys (SMA), special engineered cementitious composites (ECC), elastomeric pads embedded into columns, and post-tensioning tendons. The design of the columns, location of the bents, and selection of the loading protocol were based on pre-test analyses conducted using computer program OpenSees. The bridge model was subjected to two-horizontal components of simulated earthquake records of the 1994 Northridge earthquake. Over 340 channels of data were collected
Gloss paints in late paintings by Francis Picabia: a multi-analytical study
NASA Astrophysics Data System (ADS)
Kokkori, Maria; Hubert, Marie-Odile; Balcar, Nathalie; Barabant, Gilles; Sutherland, Ken; Casadio, Francesca
2016-01-01
In this paper, a multi-analytical approach for the study of the materials used by Francis Picabia in two paintings dating from 1949 and 1950 is reported, with a particular reference to the possible use of enamel paints. The study is complemented by analysis of paints that had the appearance of glossy enamel sampled from the artist's easel in the collection of the Comité Francis Picabia. Analysis with Fourier transform infrared spectroscopy, pyrolysis gas chromatography mass spectrometry with thermally assisted hydrolysis and methylation (THM-Py-GCMS) and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy revealed that only few paints match the composition of historical reference samples of Ripolin enamels, while the majority of the glossy paints sampled likely consist of mixtures of binders and varnishes made by the artist. This study confirms the importance of scientific testing and comparison with reference materials, when determining artists' use of enamel paints. Results should be interpreted in the context of documentary/historical evidence, for a more informed characterization of oleoresinous paint media.
NASA Technical Reports Server (NTRS)
Williams, J. G.; Mikulas, M. M., Jr.
1975-01-01
Structural efficiency studies were made to determine the weight-saving potential of graphite/epoxy composite structures for compression panel applications. Minimum-weight hat-stiffened and open-corrugation configurations were synthesized using a nonlinear mathematical programing technique. Selected configurations were built and tested to study local and Euler buckling characteristics. Test results for 23 panels critical in local buckling and six panels critical in Euler buckling are compared with analytical results obtained using the BUCLASP-2 branched plate buckling program. A weight efficiency comparison is made between composite and aluminum compression panels using metal test data generated by the NACA. Theoretical studies indicate that potential weight savings of up to 50% are possible for composite hat-stiffened panels when compared with similar aluminum designs. Weight savings of 32% to 42% were experimentally achieved. Experience to date suggests that most of the theoretical weight-saving potential is available if design deficiencies are eliminated and strict fabrication control is exercised.
Sutton, Patrick T; Ginn, Timothy R
2014-12-15
A sustainable in-well vapor stripping system is designed as a cost-effective alternative for remediation of shallow chlorinated solvent groundwater plumes. A solar-powered air compressor is used to inject air bubbles into a monitoring well to strip volatile organic compounds from a liquid to vapor phase while simultaneously inducing groundwater circulation around the well screen. An analytical model of the remediation process is developed to estimate contaminant mass flow and removal rates. The model was calibrated based on a one-day pilot study conducted in an existing monitoring well at a former dry cleaning site. According to the model, induced groundwater circulation at the study site increased the contaminant mass flow rate into the well by approximately two orders of magnitude relative to ambient conditions. Modeled estimates for 5h of pulsed air injection per day at the pilot study site indicated that the average effluent concentrations of dissolved tetrachloroethylene and trichloroethylene can be reduced by over 90% relative to the ambient concentrations. The results indicate that the system could be used cost-effectively as either a single- or multi-well point technology to substantially reduce the mass of dissolved chlorinated solvents in groundwater.
NASA Astrophysics Data System (ADS)
Sutton, Patrick T.; Ginn, Timothy R.
2014-12-01
A sustainable in-well vapor stripping system is designed as a cost-effective alternative for remediation of shallow chlorinated solvent groundwater plumes. A solar-powered air compressor is used to inject air bubbles into a monitoring well to strip volatile organic compounds from a liquid to vapor phase while simultaneously inducing groundwater circulation around the well screen. An analytical model of the remediation process is developed to estimate contaminant mass flow and removal rates. The model was calibrated based on a one-day pilot study conducted in an existing monitoring well at a former dry cleaning site. According to the model, induced groundwater circulation at the study site increased the contaminant mass flow rate into the well by approximately two orders of magnitude relative to ambient conditions. Modeled estimates for 5 h of pulsed air injection per day at the pilot study site indicated that the average effluent concentrations of dissolved tetrachloroethylene and trichloroethylene can be reduced by over 90% relative to the ambient concentrations. The results indicate that the system could be used cost-effectively as either a single- or multi-well point technology to substantially reduce the mass of dissolved chlorinated solvents in groundwater.
NASA Astrophysics Data System (ADS)
Barberini, V.; Maspero, F.; Galimberti, L.; Fusi, N.
2009-04-01
The aim of this work was the characterization, using several analytical techniques, of a sample of ancient pottery found during archaeological excavations in the 14th century's Sforza Castle in Milano. The use of a multi-analytical approach is well established in the study of archaeological materials (e.g. Tite et al. 1984, Ribechini et al. 2008). The chemical composition of the sample was determined with X-ray fluorescence spectroscopy. The chemical composition is: SiO2 61.3(±3)%, Al2O3 22.5(±2)%, Fe2O3 7.19(±6)%, K2O 3.85(±1)%, MgO 1.6(±1)%, Na2O 1.6(±4)% (probably overestimated), TiO2 1.02(±2)%, CaO 0.93(±1)%, MnO 0.15(±1)% and P2O5 0.06(±2)%. The K2O content, important when dealing with TL dating, was determined also with atomic absorption spectrophotometry. The K2O content determined with atomic absorption is 3.86(±3)%, in agreement with X-ray fluorescence analysis. The mineralogical composition of the sample was determined with X-ray powder diffraction: quartz 59.6(±1) wt%, mica 37.8(±3) wt% and feldspar (plagioclase) 2.6(±2) wt%. The sample homogeneity was assessed with X-ray computerised tomography (CT), which is a very powerful non-destructive analysis tool for 3D characterization (Sèguin, 1991). CT images show differences in materials with different X-ray absorption (mainly depending on different densities) and 3D reconstruction has many interesting archaeological applications (e.g. study of sealed jars). CT images of the studied sample showed the presence of angular fragments (probably quartz) few millimetres wide immersed in a fine grained matrix. Moreover, before and after the CT analysis, some ceramic powder was sampled to perform thermoluminescence analysis (TL, the powder used for this analysis can not be recovered). It was thus possible to evaluate the dose absorbed by the material due the X-ray irradiation. The dose absorbed after 3 hours of irradiation, the time needed for a complete scan of a 7 x 5 x 1 cm, is about 100 Gy, which
Aerial optimization and canopy penetration study of Dibrom 14 Concentrate.
Brown, James R; Reynolds, W H; Palmisano, C; Taylor, V
2005-03-01
This document describes the results of collaborative trials between St. Tammany Parish Mosquito Control, ADAPCO, Inc., and the Navy Disease Vector Ecology and Control Center, Naval Air Station, Jacksonville, FL. These tests provide data on the aerial optimization testing of Dibrom 14 Concentrate adulticide. During the week of June 17, 2002, 1 canopy penetration and 3 optimization studies were conducted in St. Tammany Parish, LA, using a Britton Norman twin turbine Islander equipped with 10-800067 flat fan nozzles. Dibrom 14 Concentrate (AMVAC Chemical Corp., Los Angeles, CA) was applied at 3.12 liter per min from a release height of 60.96 m above ground level (agl) at 140 kts indicated airspeed. This resulted in an application rate of 0.65 oz/acre. PMID:15825773
Analytical and Experimental Study of Near-Threshold Interactions Between Crack Closure Mechanisms
NASA Technical Reports Server (NTRS)
Newman, John A.; Riddell, William T.; Piascik, Robert S.
2003-01-01
The results of an analytical closure model that considers contributions and interactions between plasticity-, roughness-, and oxide-induced crack closure mechanisms are presented and compared with experimental data. The analytical model is shown to provide a good description of the combined influences of crack roughness, oxide debris, and plasticity in the near-threshold regime. Furthermore, analytical results indicate that closure mechanisms interact in a non-linear manner such that the total amount of closure is not the sum of closure contributions for each mechanism.
NASA Astrophysics Data System (ADS)
Bychenkov, V. Yu; Brantov, A. V.; Govras, E. A.
2016-03-01
The results of a 3D optimization study of ion acceleration from ultrathin solid density foils (Brantov et al 2015 Phys. Rev. Spec. Top. Accel. Beams 18 021301) are complemented with an improved analytic model of the directed Coulomb explosion. Similarly to optimizing overdense targets, we also optimize low-density targets to obtain maximum ion energy, motivated by progress in producing a new generation of low-density slab targets whose density can be very homogeneous and as low as the relativistic critical density. Using 3D simulations, we show that for the same laser pulse, the ion energy can be significantly increased with low-density targets. A new acceleration mechanism is responsible for such an increase. This mechanism is described qualitatively, and it explains an advantage of low-density targets for high-energy ion production by lasers.
Optimization studies on a Fe/Cr redox flow battery
NASA Astrophysics Data System (ADS)
Lopez-Atalaya, M.; Codina, G.; Perez, J. R.; Vazquez, J. L.; Aldaz, A.
The performance of a Fe/Cr redox flow battery which operates in bipolar mode is described. The optimization studies on electrolyte composition, temperature and membrane type are presented. These studies have achieved a coulombic efficiency of 97% and an energy efficiency of 73% for an electrolyte composition of 2.3 M HCl + 1.25 M FeCl 2 + 1.25 M CrCl 3, working at 44 °C with a current density of 40 mA/cm 2 and using the Nafion 117 membrane. A maximum discharge power density of 73 mW/cm 2 has been obtained.
Analytical study of ancient pottery from the archaeological site of Aiani, northern Greece
Iordanidis, A. Garcia-Guinea, J.
2009-04-15
The present study is a multi-analytical approach on the characterization of several potsherd samples, dated from prehistoric to hellenistic times, from Aiani, ancient Upper Macedonia, northern Greece. In particular, X-ray Diffraction (XRD), X-ray Fluorescence (XRF) and Environmental Scanning Electron Microscopy, coupled with Energy Dispersive X-ray system (ESEM-EDX) were used for the determination of the morphological, chemical and mineralogical characteristics of the potsherds. The preliminary results indicated a rather local provenance of the analyzed ancient pottery samples and a finer texture and thus better ceramic manufacture as getting to hellenistic era. The use of a silicious or calcerous raw material is probably related to the specific utilization of each ceramic vessel in ancient times. The presence of gehlenite or pyroxene minerals in the ceramic matrix indicated higher firing temperatures, while lower temperatures were deduced when finding phylosilicate minerals. The preliminary results of this study do not necessarily imply that all the pottery of this area, belonging to the same chronological type, have similar physicochemical characteristics.
Cloud-Enabled Climate Analytics-as-a-Service using Reanalysis data: A case study.
NASA Astrophysics Data System (ADS)
Nadeau, D.; Duffy, D.; Schnase, J. L.; McInerney, M.; Tamkin, G.; Potter, G. L.; Thompson, J. H.
2014-12-01
The NASA Center for Climate Simulation (NCCS) maintains advanced data capabilities and facilities that allow researchers to access the enormous volume of data generated by weather and climate models. The NASA Climate Model Data Service (CDS) and the NCCS are merging their efforts to provide Climate Analytics-as-a-Service for the comparative study of the major reanalysis projects: ECMWF ERA-Interim, NASA/GMAO MERRA, NOAA/NCEP CFSR, NOAA/ESRL 20CR, JMA JRA25, and JRA55. These reanalyses have been repackaged to netCDF4 file format following the CMIP5 Climate and Forecast (CF) metadata convention prior to be sequenced into the Hadoop Distributed File System ( HDFS ). A small set of operations that represent a common starting point in many analysis workflows was then created: min, max, sum, count, variance and average. In this example, Reanalysis data exploration was performed with the use of Hadoop MapReduce and accessibility was achieved using the Climate Data Service(CDS) application programming interface (API) created at NCCS. This API provides a uniform treatment of large amount of data. In this case study, we have limited our exploration to 2 variables, temperature and precipitation, using 3 operations, min, max and avg and using 30-year of Reanalysis data for 3 regions of the world: global, polar, subtropical.
2014-01-01
Background Nursing students may exhibit the characteristics of resistance to stress, such as hardiness, which can reduce the risk of burnout. However, we found only one published study about these phenomena among nursing students. Thus, we investigated the association between hardiness and burnout in such students. Methods An analytic, cross-sectional study was conducted among 570 nursing students from three Brazilian universities. Data were collected relating to sociodemographic characteristics, hardiness, and burnout, which we analyzed using inferential statistics. Results We observed that 64.04% of nursing students in the sample had a high level of emotional exhaustion, 35.79% had a high level of cynicism, and 87.72% had a low level of professional efficacy: these are dimensions of burnout. We also found that 48.77% had a high level of control, 61.40% a high level of commitment, and 35.44% a high level of challenge: these are dimensions of hardiness. Only 24.74% of the students experienced burnout, and 21.93% met the criteria for a hardy personality. There was a statistically significant difference between the frequency of hardiness and burnout (p = 0.033), with 68.00% of hardy students not exhibiting burnout. Conclusions Although nursing students live with educational stressors, burnout was not preponderant in our sample students; this may be linked to hardiness. Thus, given its benefits to student life and health, we recommend the development of strategies to promote hardiness among nursing students. PMID:24678676
An analytical study on artesian flow conditions in unconfined-aquifer drainage basins
NASA Astrophysics Data System (ADS)
Wang, Jun-Zhi; Jiang, Xiao-Wei; Wan, Li; Wörman, Anders; Wang, Heng; Wang, Xu-Sheng; Li, Hailong
2015-10-01
Although it has been reported that flowing artesian wells could be topographically controlled, there is no quantitative research on artesian flow conditions in unconfined aquifers. In this study, the water table, which has a lower amplitude than the land surface, is damped from the topography and used as the boundary condition to obtain the analytical solution of hydraulic head of a unit basin with a single flow system. The term artesian head is defined to characterize the condition of flowing artesian wells. The zone with positive artesian head is called artesian zone while with negative artesian head is nonartesian zone. The maximum artesian head and the size of artesian zones are found to increase with the damping factor and the anisotropy ratio, and decrease with the ratio of basin width to depth and the depth-decay exponent of hydraulic conductivity. Moreover, the artesian head increases with depth nearby the valley and decreases with depth near by the divide, and the variation rates are influenced by the decay exponent and the anisotropy ratio. Finally, the distribution of flowing artesian wells and the artesian head measurements in different depths of a borehole in a small catchment in the Ordos Plateau, Northwestern China is used to illustrate the theoretical findings. The change in artesian head with depth was used to estimate the anisotropy ratio and the decay exponent. This study opens up a new door to analyze basin-scale groundwater flow.
Analytical study of a gas-fired adsorptive air-conditioning system
Poyelle, F.; Guilleminot, J.J.; Meunier, F.
1996-11-01
Adsorptive air conditioning represents a potential alternative to chlorofluorocarbon (CFC) systems. But to compete with other systems, adsorption systems must exhibit sufficient figures of merit and energetic densities. An analytical study to predict the overall heat transfer coefficient in an adsorber has been conducted and is presented here. This study, based on a method-of-moment analysis, shows the influence of three parameters limiting the heat transfer in adsorbent beds. Heat transfer in adsorbent beds has been intensified. Using new consolidated materials, the machine utilizes two uniform temperature adsorbent beds in a cycle that incorporates both heat and mass recovery. It uses a zeolite-water pair. It is designed to produce 3 kW of cooling. Expected cooling performances are 300 W/kg of adsorbent with a coefficient of performance (COP) close to 0.8 and a cycle time of 20 minutes. The thermal conditions used to test the cycle are: the heater, 220 C; the cooler, 40 C; and the evaporation temperature, 3 C.
An analytical study on bistability of Fabry-Perot semiconductor optical amplifiers
NASA Astrophysics Data System (ADS)
Wang, Gang; Chen, Shuqiang; Yang, Huajun
2016-09-01
Optical bistabilities have been considered to be useful for sensor applications. As a typical nonlinear device, Fabry-Perot semiconductor optical amplifiers (FPSOAs) exhibit bistability under certain conditions. In this paper, the bistable characteristics in FPSOAs are investigated theoretically. Based on Adams's relationship between the incident optical intensity I in and the z-independent average intracavity intensity I av, an analytical expression of the bistable loop width in SOAs is derived. Numerical simulations confirm the accuracy of the analytical result.
Monte Carlo studies for medical imaging detector optimization
NASA Astrophysics Data System (ADS)
Fois, G. R.; Cisbani, E.; Garibaldi, F.
2016-02-01
This work reports on the Monte Carlo optimization studies of detection systems for Molecular Breast Imaging with radionuclides and Bremsstrahlung Imaging in nuclear medicine. Molecular Breast Imaging requires competing performances of the detectors: high efficiency and high spatial resolutions; in this direction, it has been proposed an innovative device which combines images from two different, and somehow complementary, detectors at the opposite sides of the breast. The dual detector design allows for spot compression and improves significantly the performance of the overall system if all components are well tuned, layout and processing carefully optimized; in this direction the Monte Carlo simulation represents a valuable tools. In recent years, Bremsstrahlung Imaging potentiality in internal radiotherapy (with beta-radiopharmaceuticals) has been clearly emerged; Bremsstrahlung Imaging is currently performed with existing detector generally used for single photon radioisotopes. We are evaluating the possibility to adapt an existing compact gamma camera and optimize by Monte Carlo its performance for Bremsstrahlung imaging with photons emitted by the beta- from 90 Y.
Optimization study on a single-cylinder compressed air engine
NASA Astrophysics Data System (ADS)
Yu, Qihui; Cai, Maolin; Shi, Yan; Xu, Qiyue
2015-11-01
The current research of compressed air engine (CAE) mainly focused on simulations and system integrations. However, energy efficiency and output torque of the CAE is limited, which restricts its application and popularization. In this paper, the working principles of CAE are briefly introduced. To set a foundation for the study on the optimization of the CAE, the basic mathematical model of working processes is set up. A pressure-compensated valve which can reduce the inertia force of the valve is proposed. To verify the mathematical model, the prototype with the newly designed pressure-compensated intake valve is built and the experiment is carried out, simulation and experimental results of the CAE are conducted, and pressures inside the cylinder and output torque of the CAE are obtained. Orthogonal design and grey relation analysis are utilized to optimize structural parameters. The experimental and optimized results show that, first of all, pressure inside the cylinder has the same changing tendency in both simulation curve and experimental curve. Secondly, the highest average output torque is obtained at the highest intake pressure and the lowest rotate speed. Thirdly, the optimization of the single-cylinder CAE can improve the working efficiency from an original 21.95% to 50.1%, an overall increase of 28.15%, and the average output torque increases also increases from 22.047 5 N • m to 22.439 N • m. This research designs a single-cylinder CAE with pressure-compensated intake valve, and proposes a structural parameters design method which improves the single-cylinder CAE performance.
Adriztina, Indri; Adnan, Adlin; Adenin, Ichwanul; Haryuna, Siti Hajar; Sarumpaet, Sorimuda
2015-01-01
Introduction There is only limited information from previous studies that suggest that auditory function may be influenced by hormones. Recent advances in the field have exposed the potential role of hormones in modulating the auditory system. Objective This study aims to investigate the relationship between menstrual cycle and outer hair cell function with audiological examination. Methods This is an analytic study with a cross-sectional design. The sampling was a systematic random sampling. We found 49 women with normal menstrual cycle and collected their data through interviews, physical examination, and examination of the ear, with otoscopic and other routine otorhinolaryngology examinations. We evaluated Tympanometry, distortion-product otoacoustic emissions (DPOAE), and pure tone audiometry. Results We found the audiometric threshold worse in the follicular phase than other phases at 4000 Hz of the right ear, and in the ovulation was found best than any other phases at 1000 Hz of the left ear with significant difference. We found significant difference of DPOAE between ovulation time and follicular phase at 3000 Hz and 1000 Hz in the left ear and between ovulation and luteal phased at 2000 Hz, 3000 Hz and 5000 Hz in the right ear and at 1000 Hz in the left ear with p < 0.05. Conclusion The result of this study showed that only a small part of audiometry threshold had a significant difference between each menstrual phase. In other words, we found no correlation between menstrual and audiometry threshold. Nonetheless, there is a correlation between menstrual cycle phase and DPOAE amplitude.
Gausachs, Mireia; Mur, Pilar; Corral, Julieta; Pineda, Marta; González, Sara; Benito, Llúcia; Menéndez, Mireia; Espinàs, Josep Alfons; Brunet, Joan; Iniesta, María Dolores; Gruber, Stephen B; Lázaro, Conxi; Blanco, Ignacio; Capellá, Gabriel
2012-01-01
The analytical algorithm of Lynch syndrome (LS) is increasingly complex. BRAF V600E mutation and MLH1 promoter hypermethylation have been proposed as a screening tool for the identification of LS. The aim of this study was to assess the clinical usefulness and cost-effectiveness of both somatic alterations to improve the yield of the diagnostic algorithm of LS. A total of 122 colorectal tumors from individuals with family history of colorectal cancer that showed microsatellite instability and/or loss of mismatch repair (MMR) protein expression were studied. MMR germline mutations were detected in 57 cases (40 MLH1, 15 MSH2 and 2 MSH6). BRAF V600E mutation was assessed by single-nucleotide primer extension. MLH1 promoter hypermethylation was assessed by methylation-specific multiplex ligation-dependent probe amplification in a subset of 71 cases with loss of MLH1 protein. A decision model was developed to estimate the incremental costs of alternative case-finding methods for detecting MLH1 mutation carriers. One-way sensitivity analysis was performed to assess robustness of estimations. Sensitivity of the absence of BRAF mutations for depiction of LS patients was 96% (23/24) and specificity was 28% (13/47). Specificity of MLH1 promoter hypermethylation for depiction of sporadic tumors was 66% (31/47) and sensitivity of 96% (23/24). The cost per additional mutation detected when using hypermethylation analysis was lower when compared with BRAF study and germinal MLH1 mutation study. Somatic hypermethylation of MLH1 is an accurate and cost-effective pre-screening method in the selection of patients that are candidates for MLH1 germline analysis when LS is suspected and MLH1 protein expression is absent. PMID:22274583
The Effects of Task Involvement Load on L2 Incidental Vocabulary Learning: A Meta-Analytic Study
ERIC Educational Resources Information Center
Huang, Shufen; Willson, Victor; Eslami, Zohreh
2012-01-01
This meta-analytic study provides a systematic statistical synthesis of the effects of output tasks on second or foreign incidental vocabulary learning. A total of 12 studies were included in this meta-analysis. Five mediator variables were examined: design quality, types of output task, time on task, genres of text, and text-target word ratios.…
ERIC Educational Resources Information Center
Goggins, S. P.; Galyen, K. D.; Petakovic, E.; Laffey, J. M.
2016-01-01
This exploratory study focuses on the design and evaluation of teaching analytics that relate social learning structure with performance measures in a massive open online course (MOOC) prototype environment. Using reflexive analysis of online learning trace data and qualitative performance measures we present an exploratory empirical study that:…
ERIC Educational Resources Information Center
Kalaian, Sema A.; Kasim, Rafa M.
2014-01-01
This meta-analytic study focused on the quantitative integration and synthesis of the accumulated pedagogical research in undergraduate statistics education literature. These accumulated research studies compared the academic achievement of students who had been instructed using one of the various forms of small-group learning methods to those who…
NASA Astrophysics Data System (ADS)
Liu, L.; Jia, Z.; Ma, X. L.; Fan, Y. R.
2013-07-01
This work concentrates on modeling the super-elastic behavior of 10wt% ballistic gelatin at 4°C and the mechanical responses at quasi-static and high-speed penetrations. Uniaxial compression and simple shearing experiments were carried out to determine the moduli in Mooney-Rivlin model describing the elastic behavior of gelatin at low strain rates. The failure mode is determined to be elastic fracture as the tensile stretch ratio exceeds a critical value. For high compression strain rates, the available results from the split Hopkinson pressure bar (SHPB) experiments for 10wt% gelatin were carefully examined and assessed. Linear relationship between the moduli and the strain rate is established. Based on these material parameters, an analytic solution of stress for the quasi-static and quasi-dynamic expansion of spherical cavity in gelatin is derived. As a consequence, the work needed to open unit volume of cavity, Ps, which is the key parameter in studying penetration problems, is linearly increasing with the characteristic strain rate. The application of Ps to our quasi-static and high-speed penetration experiments is discussed and assessed.
Collisions with Springs: A Useful Context for the Study of Analytical Dynamics
NASA Astrophysics Data System (ADS)
Twomey, Patrick; O'Sullivan, Colm; O'Riordan, John; Fahy, Stephen
2012-02-01
A recent paper in this journal describes an experimental demonstration of the conservation of total momentum before, during, and after an elastic collision between two bodies. The experiment also appears to show that total kinetic energy is conserved in the process, including during the collision. There is a danger that this may give rise to some misconception given that, in any collision that takes place over a finite time, some kinetic energy must transfer to potential energy—albeit temporarily in the case of an elastic collision. Indeed, when a collision is observed in the c.m. frame, all kinetic energy is lost momentarily. The sequence of simple experiments described below, which can be performed using standard equipment available in undergraduate laboratories, was developed so that undergraduate students could study a collision process in some detail. It was designed to enable students to gain insight into a range of important ideas in elementary analytical dynamics, including conservation of momentum, energy transfer in inelastic collisions, and coefficient of restitution. An extension of the experiment also gives insight into wave propagation in elastic media.
Kang, Shujiang; Kline, Keith L; Nair, S. Surendran; Nichols, Dr Jeff A; Post, Wilfred M; Brandt, Craig C; Wullschleger, Stan D; Wei, Yaxing; Singh, Nagendra
2013-01-01
A global energy crop productivity model that provides geospatially explicit quantitative details on biomass potential and factors affecting sustainability would be useful, but does not exist now. This study describes a modeling platform capable of meeting many challenges associated with global-scale agro-ecosystem modeling. We designed an analytical framework for bioenergy crops consisting of six major components: (i) standardized natural resources datasets, (ii) global field-trial data and crop management practices, (iii) simulation units and management scenarios, (iv) model calibration and validation, (v) high-performance computing (HPC) simulation, and (vi) simulation output processing and analysis. The HPC-Environmental Policy Integrated Climate (HPC-EPIC) model simulated a perennial bioenergy crop, switchgrass (Panicum virgatum L.), estimating feedstock production potentials and effects across the globe. This modeling platform can assess soil C sequestration, net greenhouse gas (GHG) emissions, nonpoint source pollution (e.g., nutrient and pesticide loss), and energy exchange with the atmosphere. It can be expanded to include additional bioenergy crops (e.g., miscanthus, energy cane, and agave) and food crops under different management scenarios. The platform and switchgrass field-trial dataset are available to support global analysis of biomass feedstock production potential and corresponding metrics of sustainability.
Kosek, Margaret; Guerrant, Richard L; Kang, Gagandeep; Bhutta, Zulfiqar; Yori, Pablo Peñataro; Gratz, Jean; Gottlieb, Michael; Lang, Dennis; Lee, Gwenyth; Haque, Rashidul; Mason, Carl J; Ahmed, Tahmeed; Lima, Aldo; Petri, William A; Houpt, Eric; Olortegui, Maribel Paredes; Seidman, Jessica C; Mduma, Estomih; Samie, Amidou; Babji, Sudhir
2014-11-01
Individuals in the developing world live in conditions of intense exposure to enteric pathogens due to suboptimal water and sanitation. These environmental conditions lead to alterations in intestinal structure, function, and local and systemic immune activation that are collectively referred to as environmental enteropathy (EE). This condition, although poorly defined, is likely to be exacerbated by undernutrition as well as being responsible for permanent growth deficits acquired in early childhood, vaccine failure, and loss of human potential. This article addresses the underlying theoretical and analytical frameworks informing the methodology proposed by the Etiology, Risk Factors and Interactions of Enteric Infections and Malnutrition and the Consequences for Child Health and Development (MAL-ED) cohort study to define and quantify the burden of disease caused by EE within a multisite cohort. Additionally, we will discuss efforts to improve, standardize, and harmonize laboratory practices within the MAL-ED Network. These efforts will address current limitations in the understanding of EE and its burden on children in the developing world.
Inverse patchy colloids with two and three patches. Analytical and numerical study
Kalyuzhnyi, Y. V.; Vasilyev, O. A.; Cummings, P. T.
2015-07-28
We propose an analytical solution of the multi-density Ornstein-Zernike equation supplemented by the associative Percus-Yevick closure relations specifically designed to describe the equilibrium properties of the novel class of patchy colloidal particles represented by the inverse patchy colloids with arbitrary number of patches. Using Baxter’s factorization method, we reduce solution of the problem to the solution of one nonlinear algebraic equation for the fraction of the particles with one non-bonded patch. We present closed-form expressions for the structure (structure factor) and thermodynamic (internal energy) properties of the system in terms of this fraction (and parameters of the model). We perform computer simulation studies and compare theoretical and computer simulation predictions for the pair distribution function, internal energy, and number of single and double bonds formed in the system, for two versions of the model, each with two and three patches. We consider the models with formation of the double bonds blocked by the patch-patch repulsion and the models without patch-patch repulsion. In general very good agreement between theoretical and computer simulation results is observed.
Kosek, Margaret; Guerrant, Richard L.; Kang, Gagandeep; Bhutta, Zulfiqar; Yori, Pablo Peñataro; Gratz, Jean; Gottlieb, Michael; Lang, Dennis; Lee, Gwenyth; Haque, Rashidul; Mason, Carl J.; Ahmed, Tahmeed; Lima, Aldo; Petri, William A.; Houpt, Eric; Olortegui, Maribel Paredes; Seidman, Jessica C.; Mduma, Estomih; Samie, Amidou; Babji, Sudhir
2014-01-01
Individuals in the developing world live in conditions of intense exposure to enteric pathogens due to suboptimal water and sanitation. These environmental conditions lead to alterations in intestinal structure, function, and local and systemic immune activation that are collectively referred to as environmental enteropathy (EE). This condition, although poorly defined, is likely to be exacerbated by undernutrition as well as being responsible for permanent growth deficits acquired in early childhood, vaccine failure, and loss of human potential. This article addresses the underlying theoretical and analytical frameworks informing the methodology proposed by the Etiology, Risk Factors and Interactions of Enteric Infections and Malnutrition and the Consequences for Child Health and Development (MAL-ED) cohort study to define and quantify the burden of disease caused by EE within a multisite cohort. Additionally, we will discuss efforts to improve, standardize, and harmonize laboratory practices within the MAL-ED Network. These efforts will address current limitations in the understanding of EE and its burden on children in the developing world. PMID:25305293
Yang, Shibing; Lu, Juan; Eaton, Charles B.; Harpe, Spencer; Lapane, Kate L.
2015-01-01
We sought to explore the impact of intention to treat and complex treatment use assumptions made during weight construction on the validity and precision of estimates derived from inverse-probability-of-treatment–weighted analysis. We simulated data assuming a nonexperimental design that attempted to quantify the effect of statin on lowering low-density lipoprotein cholesterol. We created 324 scenarios by varying parameter values (effect size, sample size, adherence level, probability of treatment initiation, associations between low-density lipoprotein cholesterol and treatment initiation and continuation). Four analytical approaches were used: 1) assuming intention to treat; 2) assuming complex mechanisms of treatment use; 3) assuming a simple mechanism of treatment use; and 4) assuming invariant confounders. With a continuous outcome, estimates assuming intention to treat were biased toward the null when there were nonnull treatment effect and nonadherence after treatment initiation. For each 1% decrease in the proportion of patients staying on treatment after initiation, the bias in estimated average treatment effect increased by 1%. Inverse-probability-of-treatment–weighted analyses that took into account the complex mechanisms of treatment use generated approximately unbiased estimates. Studies estimating the actual effect of a time-varying treatment need to consider the complex mechanisms of treatment use during weight construction. PMID:26316599
NASA Astrophysics Data System (ADS)
Tan, Xijuan; Song, Zhenghua; Chen, Donghua; Wang, Zhuming
2011-06-01
In this paper, the luminescence behavior of bovine serum albumin (BSA) and luminol was first studied by flow injection chemiluminescence (CL). It was found that the hyperchromic effect of luminol in the presence of BSA led to the acceleration of the electrons transferring rate of excited 3-aminophthalate, which greatly enhanced the CL intensity of luminol/dissolved oxygen reaction. The increments of CL intensity were proportional to the concentrations of BSA with a linear range from 0.01 to 7 nmol L -1. It was also found that azithromycin could inhibit the CL intensity of luminol/BSA reaction. The decrements of CL intensity were logarithm over the concentrations of azithromycin ranging from 0.1 to 700 ng mL -1. At a flow rate of 2.0 mL min -1, a complete analytical process, which included sampling and washing, could be performed within 30 s with relative standard deviations of less than 3.1%. This proposed method was successfully applied in assaying azithromycin in pharmaceutical and human serum samples with recoveries from 91.0 to 104.3%. The possible luminescence mechanism of luminol/BSA/azithromycin reaction was discussed in detail by CL, UV and fluorescence methods.
Interaction of airborne and structureborne noise radiated by plates. Volume 1: Analytical study
NASA Technical Reports Server (NTRS)
Mcgary, M. C.
1986-01-01
The interaction of airborne and structureborne noise radiated by aircraft materials was examined. The theory and results of several computer simulations of the noise radiated by thin, isotropic, rectangular aluminum plates due to fully coherent combined acoustic and vibrational inputs is presented. The most significant finding was the extremely large influence that the relative phase between inputs has on the combined noise radiation of the plates. Phase dependent effects manifest themselves as cross terms in both the dynamic and acoustic portions of the analysis. Computer simulations show that these cross terms can radically alter the combined sound power radiated by plates constructed of aircraft-type materials. The results suggest that airborne-structureborne interactive effects could be responsible for a significant portion of the overall noise radiated by aircraft-type structures in the low frequency regime. This implies that previous analytical and experimental studies may have neglected an important physical phenomenon in the analayses of the interior noise of propeller dirven aircraft.
Nair, S. Surendran; Nichols, Jeff A. {Cyber Sciences}; Post, Wilfred M; Wang, Dali; Wullschleger, Stan D; Kline, Keith L; Wei, Yaxing; Singh, Nagendra; Kang, Shujiang
2014-01-01
Contemporary global assessments of the deployment potential and sustainability aspects of biofuel crops lack quantitative details. This paper describes an analytical framework capable of meeting the challenges associated with global scale agro-ecosystem modeling. We designed a modeling platform for bioenergy crops, consisting of five major components: (i) standardized global natural resources and management data sets, (ii) global simulation unit and management scenarios, (iii) model calibration and validation, (iv) high-performance computing (HPC) modeling, and (v) simulation output processing and analysis. A case study with the HPC- Environmental Policy Integrated Climate model (HPC-EPIC) to simulate a perennial bioenergy crop, switchgrass (Panicum virgatum L.) and global biomass feedstock analysis on grassland demonstrates the application of this platform. The results illustrate biomass feedstock variability of switchgrass and provide insights on how the modeling platform can be expanded to better assess sustainable production criteria and other biomass crops. Feedstock potentials on global grasslands and within different countries are also shown. Future efforts involve developing databases of productivity, implementing global simulations for other bioenergy crops (e.g. miscanthus, energycane and agave), and assessing environmental impacts under various management regimes. We anticipated this platform will provide an exemplary tool and assessment data for international communities to conduct global analysis of biofuel biomass feedstocks and sustainability.
Vibration Based Crack Detection in a Rotating Disk. Part 1; An Analytical Study
NASA Technical Reports Server (NTRS)
Gyekenyesi, Andrew L.; Sawicki, Jerzy T.; Baaklini, George Y.
2003-01-01
This paper describes the analytical results concerning the detection of a crack in a rotating disk. The concept of the approach is based on the fact that the development of a disk crack results in a distorted strain field within the component. As a result, a minute deformation in the disk's geometry as well as a change in the system s center of mass occurs. Finite element analyses were conducted concerning a notched disk in order to define the sensitivity of the method. The notch was used to simulate an actual crack and will be the method utilized for upcoming experiments. Various notch sizes were studied. The geometric deformations and shifts of center of mass were documented as a function of rotational speed. In addition, a rotordynamic analysis of a 2-bearing, disk and shaft system was conducted. The overall response of the system was required in order to design the experimental system for operation beyond the first critical. The results of the FE analyses of the disk indicated that the overall changes in the disk s geometry and center of mass were rather small. The difference between the maximum centrifugal radial displacements between the undamaged and damaged disks at 8000 RPM was 0.00014 in. for a 0.963 in. notch length. The shift in center of mass was also of this magnitude. The next step involves running experiments to verify the analysis.
Analytical and experimental studies of heat pipe radiation cooling of hypersonic propulsion systems
NASA Technical Reports Server (NTRS)
Martin, R. A.; Merrigan, M. A.; Elder, M. G.; Sena, J. T.; Keddy, E. S.; Silverstein, C. C.
1992-01-01
Analytical and experimental studies were completed to assess the feasibility of using high-temperature heat pipes to cool hypersonic engine components. This new approach involves using heat pipes to transport heat away from the combustor, nozzle, or inlet regions, and to reject it to the environment by thermal radiation from an external heat pipe nacelle. For propulsion systems using heat pipe radiation cooling (HPRC), it is possible to continue to use hydrocarbon fuels into the Mach 4 to Mach 6 speed range, thereby enhancing the economic attractiveness of commercial or military hypersonic flight. In the second-phase feasibility program recently completed, it is found that heat loads produced by considering both convection and radiation heat transfer from the combustion gas can be handled with HPRC design modifications. The application of thermal insulation to ramburner and nozzle walls was also found to reduce the heat load by about one-half and to reduce peak HPRC system temperatures to below 2700 F. In addition, the operation of HPRC at cruise conditions of around Mach 4.5 and at an altitude of 90,000 ft lowers the peak hot-section temperatures to around 2800 F. An HPRC heat pipe was successfully fabricated and tested at Mach 5 conditions of heat flux, heat load, and temperature.
Kosek, Margaret; Guerrant, Richard L; Kang, Gagandeep; Bhutta, Zulfiqar; Yori, Pablo Peñataro; Gratz, Jean; Gottlieb, Michael; Lang, Dennis; Lee, Gwenyth; Haque, Rashidul; Mason, Carl J; Ahmed, Tahmeed; Lima, Aldo; Petri, William A; Houpt, Eric; Olortegui, Maribel Paredes; Seidman, Jessica C; Mduma, Estomih; Samie, Amidou; Babji, Sudhir
2014-11-01
Individuals in the developing world live in conditions of intense exposure to enteric pathogens due to suboptimal water and sanitation. These environmental conditions lead to alterations in intestinal structure, function, and local and systemic immune activation that are collectively referred to as environmental enteropathy (EE). This condition, although poorly defined, is likely to be exacerbated by undernutrition as well as being responsible for permanent growth deficits acquired in early childhood, vaccine failure, and loss of human potential. This article addresses the underlying theoretical and analytical frameworks informing the methodology proposed by the Etiology, Risk Factors and Interactions of Enteric Infections and Malnutrition and the Consequences for Child Health and Development (MAL-ED) cohort study to define and quantify the burden of disease caused by EE within a multisite cohort. Additionally, we will discuss efforts to improve, standardize, and harmonize laboratory practices within the MAL-ED Network. These efforts will address current limitations in the understanding of EE and its burden on children in the developing world. PMID:25305293
NASA Astrophysics Data System (ADS)
Subhash, P. V.; Madhavan, S.; Sakthivel, N.; Mishra, V.; Majalee, Aaditya V.; Pahari, P.; Chaturvedi, S.
2011-08-01
This paper reports a computational optimization study for an inverse z-pinch magnetized target fusion system (MTF). This has been carried out by varying various parameters such as the magnetizing current, the initial liner radius and thickness, liner length, etc. One-dimensional (1D) magneto-hydrodynamic (MHD) calculations are used for this purpose. Capacitor bank parameters are held constant, as is also the inner conductor radius. The Kadomtsev stability parameter Q0 is kept constant at 0.9 and the maximum plasma β at 0.4. The optimization study has yielded several parametric sets with an energy gain of more than unity, i.e. fusion energy output that exceeds the initial energy in the capacitor bank. A physical explanation for the local optimal points is provided through an energy flow analysis. For one case with energy gain exceeding unity, a simple liner stability analysis has been performed. This involves analytical calculations of the time points at which different liner modes become unstable. For these analytical studies, time-dependent parameters, such as liner acceleration, effective thickness of the liner region that still remains solid, and effective material strength, are obtained from 1D MHD simulations.
NASA Astrophysics Data System (ADS)
Abdul-Aziz, Ali; Krause, David
2006-03-01
A new in-house test capability has been developed at the NASA Glenn Research Center to conduct highly critical tests in support of major and significant components of the Stirling Radioisotope Generator (SRG). It is to aid the development of analytical life prediction methodology and to experimentally assist in verifying the flight-design component's life. Components within the SRG such as the heater head pressure vessel endure a very high temperature environment for a long period of time. Such conditions impose life-limiting failure by means of material creep, a slow gradual increase in strain which leads to an eventual failure of the pressure vessel. To properly evaluate the performance and assist in the design of this component, testing under multiaxial loading setting is essential, since the heater head is subjected to a biaxial state of stress. Thus, the current work undertakes conducting analytical studies under equibiaxial and non-equi-biaxial loadings situations at various temperatures emulating creep environment. These analytical activities will utilize the finite element method to analyze cruciform type specimens both, under linear elastic and creep conditions. And further to calibrate the in-plane biaxial-test system. The specimen finite element model is generated with MSC/Patran [1] and analytical calculations are conducted with MARC and ANSYS finite element codes [2-3]. Complementing these calculations will undertake conducting experimental tests. However, only results pertaining to the analytical studies are reported and their impact on estimating the life of the component is evaluated.
Compressed Air System Optimization: Case Study Food Industry in Indonesia
NASA Astrophysics Data System (ADS)
Widayati, Endang; Nuzahar, Hasril
2016-01-01
Compressors and compressed air systems was one of the most important utilities in industries or factories. Approximately 10% of the cost of electricity in the industry was used to produce compressed air. Therefore the potential for energy savings in the compressors and compressed air systems had a big challenge. This field was conducted especially in Indonesia food industry or factory. Compressed air system optimization was a technique approach to determine the optimal conditions for the operation of compressors and compressed air systems that included evaluation of the energy needs, supply adjustment, eliminating or reconfiguring the use and operation of inefficient, changing and complementing some equipment and improving operating efficiencies. This technique gave the significant impact for energy saving and costs. The potential savings based on this study through measurement and optimization e.g. system that lowers the pressure of 7.5 barg to 6.8 barg would reduce energy consumption and running costs approximately 4.2%, switch off the compressor GA110 and GA75 was obtained annual savings of USD 52,947 ≈ 455 714 kWh, running GA75 light load or unloaded then obtained annual savings of USD 31,841≈ 270,685 kWh, install new compressor 2x132 kW and 1x 132 kW VSD obtained annual savings of USD 108,325≈ 928,500 kWh. Furthermore it was needed to conduct study of technical aspect of energy saving potential (Investment Grade Audit) and performed Cost Benefit Analysis. This study was one of best practice solutions how to save energy and improve energy performance in compressors and compressed air system.
Igor D. Kaganovich; Edward A. Startsev; Ronald C. Davidson
2003-11-25
Plasma neutralization of an intense ion beam pulse is of interest for many applications, including plasma lenses, heavy ion fusion, high energy physics, etc. Comprehensive analytical, numerical, and experimental studies are underway to investigate the complex interaction of a fast ion beam with a background plasma. The positively charged ion beam attracts plasma electrons, and as a result the plasma electrons have a tendency to neutralize the beam charge and current. A suite of particle-in-cell codes has been developed to study the propagation of an ion beam pulse through the background plasma. For quasi-steady-state propagation of the ion beam pulse, an analytical theory has been developed using the assumption of long charge bunches and conservation of generalized vorticity. The analytical results agree well with the results of the numerical simulations. The visualization of the data obtained in the numerical simulations shows complex collective phenomena during beam entry into and ex it from the plasma.
Quality of Public Hospitals Websites: A Cross-Sectional Analytical Study in Iran
Salarvand, Shahin; Samadbeik, Mahnaz; Tarrahi, Mohammad Javad; Salarvand, Hamed
2016-01-01
Introduction: Nowadays, hospitals have turned increasingly towards the Internet and develop their own web presence. Hospital Websites could be operating as effective web resources of information and interactive communication mediums to enhance hospital services to the public. Aim: Therefore, the aim of this study was to assess the quality of websites in Tehran’s public hospitals. Material and methods: This cross-sectional analysis involved all public hospitals in Iran’s capital city, Tehran, with a working website or subsites between April and June, 2014 (N=59). The websites were evaluated using three validated instruments: a localized checklist, Google page rank, and the Alexa traffic ranking. The mentioned checklist consisted of 112 items divided into five sections: technical characteristics, hospital information and facilities, medical services, interactive on-line services and external activities. Data were analyzed using descriptive and analytical statistics. Results: The mean website evaluation score was 45.7 out of 224 for selected public hospitals. All the studied websites were in the weak category based on the earned quality scores. There was no statistically significant association between the website evaluation score with Google page rank (P=0.092), Alexa global traffic rank and Alexa traffic rank in Iran (P>0.05). The hospital websites had a lower quality score in the interactive online services and external activities criteria in comparing to other criteria. Due to the low quality level of the studied websites and the importance of hospital portals in providing information and services on the Internet, the authorities should do precise planning for the appreciable improvement in the quality of hospital websites. PMID:27147806
Bonaduce, Ilaria; Carlyle, Leslie; Colombini, Maria Perla; Duce, Celia; Ferrari, Carlo; Ribechini, Erika; Selleri, Paola; Tiné, Maria Rosaria
2012-01-01
This paper presents an analytical investigation of paint reconstructions prepared with linseed oil that have undergone typical 19th century treatments in preparation for painting. The oil was mechanically extracted from the same seed lot, which was then processed by various methods: water washing, heat treatments, and the addition of driers, with and without heat. A modern process lead white (Dutch source, Schoonhoven) and a commercially available vine black were used as pigments. The reconstructions were prepared in 1999, and naturally aged from then onwards. We compared thermogravimetric analysis (TG), which yields macromolecular information, with gas chromatography-mass spectrometry (GC-MS) and direct exposure mass spectrometry (DEMS), which both provide molecular information. The study enabled us to quantitatively demonstrate, for the first time, that the parameters used to identify drying oils are deeply influenced by the history of the paint. In particular, here we show that the ratio between the relative amounts of palmitic and stearic acid (P/S), which is used as an index for differentiating between drying oils, is extremely dependent on the pigments present and the age of the paint. Moreover the study revealed that neither the P/S parameter nor the ratios between the relative amounts of the various dicarboxylic acids (azelaic over suberic and azelaic over sebacic) can be used to trace the sorts of pre-treatment undergone by the oil investigated in this study. The final results represent an important milestone for the scientific community working in the field, highlighting that further research is still necessary to solve the identification of drying oils in works of art. PMID:23166642
Bonaduce, Ilaria; Carlyle, Leslie; Colombini, Maria Perla; Duce, Celia; Ferrari, Carlo; Ribechini, Erika; Selleri, Paola; Tiné, Maria Rosaria
2012-01-01
This paper presents an analytical investigation of paint reconstructions prepared with linseed oil that have undergone typical 19th century treatments in preparation for painting. The oil was mechanically extracted from the same seed lot, which was then processed by various methods: water washing, heat treatments, and the addition of driers, with and without heat. A modern process lead white (Dutch source, Schoonhoven) and a commercially available vine black were used as pigments. The reconstructions were prepared in 1999, and naturally aged from then onwards. We compared thermogravimetric analysis (TG), which yields macromolecular information, with gas chromatography-mass spectrometry (GC-MS) and direct exposure mass spectrometry (DEMS), which both provide molecular information. The study enabled us to quantitatively demonstrate, for the first time, that the parameters used to identify drying oils are deeply influenced by the history of the paint. In particular, here we show that the ratio between the relative amounts of palmitic and stearic acid (P/S), which is used as an index for differentiating between drying oils, is extremely dependent on the pigments present and the age of the paint. Moreover the study revealed that neither the P/S parameter nor the ratios between the relative amounts of the various dicarboxylic acids (azelaic over suberic and azelaic over sebacic) can be used to trace the sorts of pre-treatment undergone by the oil investigated in this study. The final results represent an important milestone for the scientific community working in the field, highlighting that further research is still necessary to solve the identification of drying oils in works of art. PMID:23166642
Bonaduce, Ilaria; Carlyle, Leslie; Colombini, Maria Perla; Duce, Celia; Ferrari, Carlo; Ribechini, Erika; Selleri, Paola; Tiné, Maria Rosaria
2012-01-01
This paper presents an analytical investigation of paint reconstructions prepared with linseed oil that have undergone typical 19th century treatments in preparation for painting. The oil was mechanically extracted from the same seed lot, which was then processed by various methods: water washing, heat treatments, and the addition of driers, with and without heat. A modern process lead white (Dutch source, Schoonhoven) and a commercially available vine black were used as pigments. The reconstructions were prepared in 1999, and naturally aged from then onwards. We compared thermogravimetric analysis (TG), which yields macromolecular information, with gas chromatography-mass spectrometry (GC-MS) and direct exposure mass spectrometry (DEMS), which both provide molecular information. The study enabled us to quantitatively demonstrate, for the first time, that the parameters used to identify drying oils are deeply influenced by the history of the paint. In particular, here we show that the ratio between the relative amounts of palmitic and stearic acid (P/S), which is used as an index for differentiating between drying oils, is extremely dependent on the pigments present and the age of the paint. Moreover the study revealed that neither the P/S parameter nor the ratios between the relative amounts of the various dicarboxylic acids (azelaic over suberic and azelaic over sebacic) can be used to trace the sorts of pre-treatment undergone by the oil investigated in this study. The final results represent an important milestone for the scientific community working in the field, highlighting that further research is still necessary to solve the identification of drying oils in works of art.
NASA Technical Reports Server (NTRS)
Pindera, Marek-Jerzy; Salzar, Robert S.; Williams, Todd O.
1993-01-01
The utility of a recently developed analytical micromechanics model for the response of metal matrix composites under thermal loading is illustrated by comparison with the results generated using the finite-element approach. The model is based on the concentric cylinder assemblage consisting of an arbitrary number of elastic or elastoplastic sublayers with isotropic or orthotropic, temperature-dependent properties. The elastoplastic boundary-value problem of an arbitrarily layered concentric cylinder is solved using the local/global stiffness matrix formulation (originally developed for elastic layered media) and Mendelson's iterative technique of successive elastic solutions. These features of the model facilitate efficient investigation of the effects of various microstructural details, such as functionally graded architectures of interfacial layers, on the evolution of residual stresses during cool down. The available closed-form expressions for the field variables can readily be incorporated into an optimization algorithm in order to efficiently identify optimal configurations of graded interfaces for given applications. Comparison of residual stress distributions after cool down generated using finite-element analysis and the present micromechanics model for four composite systems with substantially different temperature-dependent elastic, plastic, and thermal properties illustrates the efficacy of the developed analytical scheme.
A new mathematical model in space optimization: A case study
NASA Astrophysics Data System (ADS)
Abdullah, Kamilah; Kamis, Nor Hanimah; Sha'ari, Nor Shahida; Muhammad Halim, Nurul Suhada; Hashim, Syaril Naqiah
2013-04-01
Most of higher education institutions provide certain area known as learning centre for their students to study or having group discussions. However, some of the learning centers are not provided by optimum number of tables and seats to accommodate the students sufficiently. This study proposed a new mathematical model in optimizing the number of tables and seats at Laman Najib, Faculty of Computer and Mathematical Sciences, Universiti Teknologi MARA (UiTM) Shah Alam. An improvement of space capacity with maximum number of students who can facilitate the Laman Najib at the same time has been made by considering the type and size of tables that are appropriate for student's discussions. Our finding is compared with the result of Simplex method of linear programming to ensure that our new model is valid and consistent with other existing approaches. As a conclusion, we found that the round-type tables with six seats provide the maximum number of students who can use Laman Najib for their discussions or group studying. Both methods are also practical to use as alternative approaches in solving other space optimization problems.
Caregiver's education level and child's dental caries in African Americans: a path analytic study.
Heima, Masahiro; Lee, Wonik; Milgrom, Peter; Nelson, Suchita
2015-01-01
The objective of this study was to investigate the influence of caregiver education level on children's dental caries mediated by both caregiver and child oral health behaviors. Participants were 423 low-income African American kindergarteners and their caregivers who were part of a school-based randomized clinical trial. Path analysis tested the hypothesis that caregiver education level affected untreated dental caries and cumulative overall caries experience (decayed or filled teeth) through the mediating influence of frequency of dental visits, use of routine care, and frequency of toothbrushing for both the caregiver and the child. The results supported the hypothesis: caregivers who completed high school were 1.76 times more likely to visit dentists compared with those who did not complete high school (e(0.56) = 1.76, 95% CI: 1.03-2.99), which in turn was associated with 5.78 times greater odds of dental visits among their children (e(1.76) = 5.78, 95% CI: 3.53-9.48). Children's dental visits, subsequently, were associated with 26% fewer untreated decayed teeth compared with children without dental visits (e(-0.31) = 0.74, 95% CI: 0.60-0.91). However, this path was not present in the model with overall caries experience. Additionally, caregiver education level was directly associated with 34% less untreated decayed teeth (e(-0.42) = 0.66, 95% CI: 0.54-0.79) and 28% less decayed or filled teeth (e(-0.32) = 0.72, 95% CI: 0.60-0.88) among the children. This study overcomes important conceptual and analytic limitations in the existing literature. The findings confirm the role of caregiver education in child dental caries and indicate that caregiver's behavioral factors are important mediators of child oral health.
Caregiver's education level and child's dental caries in African Americans: a path analytic study.
Heima, Masahiro; Lee, Wonik; Milgrom, Peter; Nelson, Suchita
2015-01-01
The objective of this study was to investigate the influence of caregiver education level on children's dental caries mediated by both caregiver and child oral health behaviors. Participants were 423 low-income African American kindergarteners and their caregivers who were part of a school-based randomized clinical trial. Path analysis tested the hypothesis that caregiver education level affected untreated dental caries and cumulative overall caries experience (decayed or filled teeth) through the mediating influence of frequency of dental visits, use of routine care, and frequency of toothbrushing for both the caregiver and the child. The results supported the hypothesis: caregivers who completed high school were 1.76 times more likely to visit dentists compared with those who did not complete high school (e(0.56) = 1.76, 95% CI: 1.03-2.99), which in turn was associated with 5.78 times greater odds of dental visits among their children (e(1.76) = 5.78, 95% CI: 3.53-9.48). Children's dental visits, subsequently, were associated with 26% fewer untreated decayed teeth compared with children without dental visits (e(-0.31) = 0.74, 95% CI: 0.60-0.91). However, this path was not present in the model with overall caries experience. Additionally, caregiver education level was directly associated with 34% less untreated decayed teeth (e(-0.42) = 0.66, 95% CI: 0.54-0.79) and 28% less decayed or filled teeth (e(-0.32) = 0.72, 95% CI: 0.60-0.88) among the children. This study overcomes important conceptual and analytic limitations in the existing literature. The findings confirm the role of caregiver education in child dental caries and indicate that caregiver's behavioral factors are important mediators of child oral health. PMID:25661111
Industrial Cogeneration Optimization Program: A summary of two studies
NASA Astrophysics Data System (ADS)
1981-08-01
Two industrial cogeneration optimization programs were performed to examine the economic and energy saving impacts of adding cogeneration to site specific plants in the chemical, food, pulp and paper, petroleum refining, and textile industries. Industrial cogeneration is reviewed. The two parallel ICOP studies are described. The five industrial sectors are also described, followed by highlights of each of the site specific case studies. Steam turbine cogeneration systems fired by coal or alternative fuels are generally the most attractive in terms of economic performance and oil/gas savings potential. Of the 15 cogeneration systems selected as optimum in the ICOP studies, 11 were coal or wood fired steam turbines. By contrast, gas turbines, combined cycles, and diesel engines, which are limited to oil or gas firing, are usually less economical.
Passive scalar mixing: Analytic study of time scale ratio, variance, and mix rate
NASA Astrophysics Data System (ADS)
Ristorcelli, J. R.
2006-07-01
Some very reasonable approximations, consistent with numerical and experimental evidence, were applied to the skewness and palinstrophy coefficients in the dissipation equations to produce a simple closed moment model for mixing. Such a model, first suggested on the grounds of a Taylor microscale self-similarity of the scalar field, was studied numerically by Gonzalez and Fall ["The approach to self-preservation of scalar fluctuation decay in isotropic turbulence," Phys. Fluids 10, 654 (1998)]. Here, in a somewhat old fashioned and physically meaningful style, analytic solutions to the four coupled nonlinear moment equations for mixing by decaying and forced stationary turbulence, are given. Analytic expressions for the variance ⟨c2⟩, the mixing rate ɛc, and the time scale ratio r(t ) are derived and compared in different mixing situations. The solutions show the sensitive dependence on the initial relative length ratio as studied experimentally by Warhaft and Lumley ["An experimental study of the decay of temperature fluctuations in grid-generated turbulence," J. Fluid Mech. 88, 659 (1978)], and simulated by Eswaran and Pope ["Direct numerical simulation of the turbulent mixing of a passive scalar," Phys. Fluids 31, 506 (1988)]. The length scale ratio saturation effect predicted by Durbin ["Analysis of the decay of temperature fluctuations in isotropic turbulence," Phys. Fluids 25, 1328 (1982)], resolving the apparent contradiction with the results of Sreenivasan, Tavoularis, and Corrsin ["Temperature fluctuations and scales in grid generated turbulence," J. Fluid Mech. 100, 597 (1980)] is predicted. For stationary turbulence the solutions indicate, in contradistinction to the power law "stirring" result predicted by a stochastic Lagrangian analysis, that the mixing is asymptotically exponential as shown in the phenomenological analysis of Corrsin ["The isotropic turbulent mixer," AIChE J. 10, 870 (1964)]. That the time scale ratio solution also depends on
NASA Astrophysics Data System (ADS)
Huang, Y. G.; Wang, L. G.; Lu, Y. L.; Chen, J. R.; Zhang, J. H.
2015-09-01
Based on the two-dimensional elasticity theory, this study established a mechanical model under chordally opposing distributed compressive loads, in order to perfect the theoretical foundation of the flattened Brazilian splitting test used for measuring the indirect tensile strength of rocks. The stress superposition method was used to obtain the approximate analytic solutions of stress components inside the flattened Brazilian disk. These analytic solutions were then verified through a comparison with the numerical results of the finite element method (FEM). Based on the theoretical derivation, this research carried out a contrastive study on the effect of the flattened loading angles on the stress value and stress concentration degree inside the disk. The results showed that the stress concentration degree near the loading point and the ratio of compressive/tensile stress inside the disk dramatically decreased as the flattened loading angle increased, avoiding the crushing failure near-loading point of Brazilian disk specimens. However, only the tensile stress value and the tensile region were slightly reduced with the increase of the flattened loading angle. Furthermore, this study found that the optimal flattened loading angle was 20°-30°; flattened load angles that were too large or too small made it difficult to guarantee the central tensile splitting failure principle of the Brazilian splitting test. According to the Griffith strength failure criterion, the calculative formula of the indirect tensile strength of rocks was derived theoretically. This study obtained a theoretical indirect tensile strength that closely coincided with existing and experimental results. Finally, this paper simulated the fracture evolution process of rocks under different loading angles through the use of the finite element numerical software ANSYS. The modeling results showed that the Flattened Brazilian Splitting Test using the optimal loading angle could guarantee the tensile
Light therapy in the treatment of patients with bipolar depression: A meta-analytic study.
Tseng, Ping-Tao; Chen, Yen-Wen; Tu, Kun-Yu; Chung, Weilun; Wang, Hung-Yu; Wu, Ching-Kuan; Lin, Pao-Yen
2016-06-01
Light therapy (LT) has been widely used in the treatment of seasonal affective disorder. Recently some evidence indicated that LT may play a role in bipolar depression, either as monotherapy or in combination with total sleep deprivation (TSD). However, the studies examining the treatment effect of LT in bipolar depression resulted in inconsistent findings. To clarify the role of LT in the disorder, we conducted a meta-analysis to compare the efficacy of LT in the treatment of bipolar depression. The results of individual studies were synthesized by a random effects model. Nine studies including 489 patients with bipolar depression were included in this current meta-analysis. We found that disease severity was significantly decreased after LT, in both with and without TSD, and with concomitant medication (p<0.001). Augmentation treatment with LT significantly decreased disease severity compared to treatment without LT (p=0.024). Our results highlight the significant efficacy of LT, either as monotherapy or in combination with TSD, in the treatment of bipolar depression. However, the detailed mechanism of LT still remains elusive. Further well-designed controlled trials are required to investigate the optimal intensity and frequency of LT in the treatment of bipolar depression. PMID:26993616
Light therapy in the treatment of patients with bipolar depression: A meta-analytic study.
Tseng, Ping-Tao; Chen, Yen-Wen; Tu, Kun-Yu; Chung, Weilun; Wang, Hung-Yu; Wu, Ching-Kuan; Lin, Pao-Yen
2016-06-01
Light therapy (LT) has been widely used in the treatment of seasonal affective disorder. Recently some evidence indicated that LT may play a role in bipolar depression, either as monotherapy or in combination with total sleep deprivation (TSD). However, the studies examining the treatment effect of LT in bipolar depression resulted in inconsistent findings. To clarify the role of LT in the disorder, we conducted a meta-analysis to compare the efficacy of LT in the treatment of bipolar depression. The results of individual studies were synthesized by a random effects model. Nine studies including 489 patients with bipolar depression were included in this current meta-analysis. We found that disease severity was significantly decreased after LT, in both with and without TSD, and with concomitant medication (p<0.001). Augmentation treatment with LT significantly decreased disease severity compared to treatment without LT (p=0.024). Our results highlight the significant efficacy of LT, either as monotherapy or in combination with TSD, in the treatment of bipolar depression. However, the detailed mechanism of LT still remains elusive. Further well-designed controlled trials are required to investigate the optimal intensity and frequency of LT in the treatment of bipolar depression.
NASA Astrophysics Data System (ADS)
Abd El-Hameed, Afaf M.
2015-12-01
The present research concerns on the study of laser-powered solar panels used for space applications. A mathematical model representing the laser effects on semiconductors has been developed. The temperature behavior and heat flow on the surface and through a slab has been studied after exposed to nano-second pulsed laser. The model is applied on two different types of common active semiconductor materials that used for photovoltaic cells fabrication as silicon (Si), and gallium arsenide (GaAs). These materials are used for receivers' manufacture for laser beamed power in space. Various values of time are estimated to clarify the heat flow through the material sample and generated under the effects of pulsed laser irradiation. These effects are theoretically studied in order to determine the performance limits of the solar cells when they are powered by laser radiation during the satellite eclipse. Moreover, the obtained results are carried out to optimize conversion efficiency of photovoltaic cells and may be helpful to give more explanation for layout of the light-electricity space systems.
Hadjitheodorou, Amalia; Kalosakas, George
2014-09-01
We investigate, both analytically and numerically, diffusion-controlled drug release from composite spherical formulations consisting of an inner core and an outer shell of different drug diffusion coefficients. Theoretically derived analytical results are based on the exact solution of Fick's second law of diffusion for a composite sphere, while numerical data are obtained using Monte Carlo simulations. In both cases, and for the range of matrix parameter values considered in this work, fractional drug release profiles are described accurately by a stretched exponential function. The release kinetics obtained is quantified through a detailed investigation of the dependence of the two stretched exponential release parameters on the device characteristics, namely the geometrical radii of the inner core and outer shell and the corresponding drug diffusion coefficients. Similar behaviors are revealed by both the theoretical results and the numerical simulations, and approximate analytical expressions are presented for the dependencies. PMID:25063169
Source mask optimization study based on latest Nikon immersion scanner
NASA Astrophysics Data System (ADS)
Zhu, Jun; Wei, Fang; Chen, Lijun; Zhang, Chenming; Zhang, Wei; Nishinaga, Hisashi; El-Sewefy, Omar; Gao, Gen-Sheng; Lafferty, Neal; Meiring, Jason; Zhang, Recoo; Zhu, Cynthia
2016-03-01
The 2x nm logic foundry node has many challenges since critical levels are pushed close to the limits of low k1 ArF water immersion lithography. For these levels, improvements in lithographic performance can translate to decreased rework and increased yield. Source Mask Optimization (SMO) is one such route to realize these image fidelity improvements. During SMO, critical layout constructs are intensively optimized in both the mask and source domain, resulting in a solution for maximum lithographic entitlement. From the hardware side, advances in source technology have enabled free-form illumination. The approach allows highly customized illumination, enabling the practical application of SMO sources. The customized illumination sources can be adjusted for maximum versatility. In this paper, we present a study on a critical layer of an advanced foundry logic node using the latest ILT based SMO software, paired with state-of-the-art scanner hardware and intelligent illuminator. Performance of the layer's existing POR source is compared with the ideal SMO result and the installed source as realized on the intelligent illuminator of an NSR-S630D scanner. Both simulation and on-silicon measurements are used to confirm that the performance of the studied layer meets established specifications.
Nasiri, Hamid; Ebrahimi, Amrollah; Zahed, Arash; Arab, Mostafa; Samouei, Rahele
2015-05-01
Functional neurological symptom disorder commonly presents with symptoms and defects of sensory and motor functions. Therefore, it is often mistaken for a medical condition. It is well known that functional neurological symptom disorder more often caused by psychological factors. There are three main approaches namely analytical, cognitive and biological to manage conversion disorder. Any of such approaches can be applied through short-term treatment programs. In this case, study a 12-year-old boy with the diagnosed functional neurological symptom disorder (psychogenic myopia) was put under a cognitive-analytical treatment. The outcome of this treatment modality was proved successful.
Nasiri, Hamid; Ebrahimi, Amrollah; Zahed, Arash; Arab, Mostafa; Samouei, Rahele
2015-01-01
Functional neurological symptom disorder commonly presents with symptoms and defects of sensory and motor functions. Therefore, it is often mistaken for a medical condition. It is well known that functional neurological symptom disorder more often caused by psychological factors. There are three main approaches namely analytical, cognitive and biological to manage conversion disorder. Any of such approaches can be applied through short-term treatment programs. In this case, study a 12-year-old boy with the diagnosed functional neurological symptom disorder (psychogenic myopia) was put under a cognitive-analytical treatment. The outcome of this treatment modality was proved successful. PMID:26487881
NASA Astrophysics Data System (ADS)
Mazzeo, Rocco; Prati, Silvia; Quaranta, Marta; Sciutto, Giorgia
The present review intends to give an overview on the type of information that is possible to gather from the application of different non-invasive and micro-destructive analytical techniques. Typically, methods that require the withdrawal of a sample, such as metallography, SEM-EDS, AAS, FTIR and Py-GC-MS are employed. Through their use, it is possible to identify the material constitution, to evaluate the degradation behavior and the state of conservation of excavated bronze artefacts. It is also underlined how a non-invasive approach might be used whenever no sampling is allowed, though some limitation should be considered. Furthermore, analytical techniques play an important role in the characterisation and evaluation of the effectiveness of protective coatings and corrosion inhibitors before and after restoration procedures. An interesting aspect is the implication of science for the recognition of forgeries, when analytical studies provide evidences able to prove or deny objects' authenticity.
Analytical and experimental study of control effort associated with model reference adaptive control
NASA Technical Reports Server (NTRS)
Messer, R. S.; Haftka, R. T.; Cudney, H. H.
1992-01-01
Numerical simulation results presently obtained for the performance of model reference adaptive control (MRAC) are experimentally verified, with a view to accounting for differences between the plant and the reference model after the control function has been brought to bear. MRAC is both experimentally and analytically applied to a single-degree-of-freedom system, as well as analytically to a MIMO system having controlled differences between the reference model and the plant. The control effort is noted to be sensitive to differences between the plant and the reference model.
Metamaterial structure design optimization: A study of the cylindrical cloak
NASA Astrophysics Data System (ADS)
Paul, Jason V.
Previously, Transformational Optics (TO) has been used as a foundation for designing cylindrical cloaks. The TO method uses a coordinate transform to dictate an anisotropic material parameter gradient in a cylinder coating that guides waves around the cylinder to reduce the Radar Cross Section (RCS). The problem is that the material parameters required for the TO cloak are not physically realizable and thus must be approximated. This problem is compounded by the fact that any approximation deviates from the ideal design and will allow fields to penetrate the cloak layer and interact with the object to be cloaked. Since the TO method does not account for this interaction, approximating the ideal TO parameters is doomed to suboptimal results. However, through the use of a Green's function, an optimized isotropic cloaked cylinder can be designed in which all of the physics are accounted for. If the contribution due to the scatterer is 0, then the observer, regardless of position, will only observe the contribution due to the source and thus the object is cloaked from observation. The contribution due to the scatterer is then used as a cost functional with an optimization algorithm to find the optimal parameters of an isotropic cloaked cylinder. Although the material parameters in this design method can be fulfilled by any material, metamaterials are used to study their viability and assumptions in this application. This process culminates in the design, fabrication and measurements of a cloaked cylinder made of metamaterials that operate outside of their resonant bands. We show bistatic RCS reduction for nearly every angle along with monostatic RCS reduction for nearly every frequency in the range of 5GHz--15GHz. Most importantly, the experimental results validate the use of a Green's function based design approach and the implementation of metamaterials for normally incident energy.
ERIC Educational Resources Information Center
Ryberg, Thomas; Dirckinck-Holmfeld, Lone
2008-01-01
This paper sets out to problematise generational categories such as "Power Users" or "New Millennium Learners" by discussing these in the light of recent research on youth and information and communication technology. We then suggest analytic and conceptual pathways to engage in more critical and empirically founded studies of young people's…
ERIC Educational Resources Information Center
Burdick, Hal; Swartz, Carl W.; Stenner, A. Jackson; Fitzgerald, Jill; Burdick, Don; Hanlon, Sean T.
2013-01-01
The purpose of the study was to explore the validity of a novel computer-analytic developmental scale, the Writing Ability Developmental Scale. On the whole, collective results supported the validity of the scale. It was sensitive to writing ability differences across grades and sensitive to within-grade variability as compared to human-rated…
The GRE Analytical Score as a Predictor for Admission to Ph.D. Candidacy: A Two Year Study.
ERIC Educational Resources Information Center
Mowsesian, Richard; Hays, William L.
The purpose of this study was to test the predictive efficiency of the Graduate Record Examination Analytical (GRE-A) score when used in combination with other predictors for doctoral candidacy decisions in an educational psychology department. It was hypothesized that the GRE-A would be a more efficient predictor than faculty ratings on a…
ERIC Educational Resources Information Center
Lintao, Rachelle B.; Erfe, Jonathan P.
2012-01-01
This study purports to foster the understanding of profession-based academic writing in two different cultural conventions by examining the rhetorical moves employed by American and Philippine thesis introductions in Architecture using Swales' 2004 Revised CARS move-analytic model as framework. Twenty (20) Master's thesis introductions in…
ERIC Educational Resources Information Center
Grigorenko, Elena L.; Sternberg, Robert J.
2001-01-01
Studied the efficacy of the triarchic theory of intelligence as a basis for predicting adaptive functioning in a rapidly changing society, that of Russia. Results of intelligence measures administered to 452 women and 293 men show that analytical, practical, and creative intelligence all relate in some degree to self-reported everyday adaptive…
Mahakrishnan, Sathiya; Chakraborty, Subrata; Vijay, Amrendra
2016-09-15
Diffusion, an emergent nonequilibrium transport phenomenon, is a nontrivial manifestation of the correlation between the microscopic dynamics of individual molecules and their statistical behavior observed in experiments. We present a thorough investigation of this viewpoint using the mathematical tools of quantum scattering, within the framework of Boltzmann transport theory. In particular, we ask: (a) How and when does a normal diffusive transport become anomalous? (b) What physical attribute of the system is conceptually useful to faithfully rationalize large variations in the coefficient of normal diffusion, observed particularly within the dynamical environment of biological cells? To characterize the diffusive transport, we introduce, analogous to continuous phase transitions, the curvature of the mean square displacement as an order parameter and use the notion of quantum scattering length, which measures the effective interactions between the diffusing molecules and the surrounding, to define a tuning variable, η. We show that the curvature signature conveniently differentiates the normal diffusion regime from the superdiffusion and subdiffusion regimes and the critical point, η = ηc, unambiguously determines the coefficient of normal diffusion. To solve the Boltzmann equation analytically, we use a quantum mechanical expression for the scattering amplitude in the Boltzmann collision term and obtain a general expression for the effective linear collision operator, useful for a variety of transport studies. We also demonstrate that the scattering length is a useful dynamical characteristic to rationalize experimental observations on diffusive transport in complex systems. We assess the numerical accuracy of the present work with representative experimental results on diffusion processes in biological systems. Furthermore, we advance the idea of temperature-dependent effective voltage (of the order of 1 μV or less in a biological environment, for example
NASA Astrophysics Data System (ADS)
Ferraris, C.; Folco, L.; Mellini, M.
2002-10-01
Sixteen texturally different (porphyritic, barred, radial, cryptocrystalline) FeO-rich chondrules from the unequilibrated ordinary chondrites Brownfield, Frontier Mountain (FRO) 90003 and FRO 90032 were characterized by optical and scanning electron microscopy and then thoroughly studied by transmission and analytical electron microscopy. Nanotextural and nanochemical data indicate similar thermal evolution for chondrules of the same textural groups; minor, yet meaningful differences occur among the different groups. Olivine is the earliest phase formed and crystallizes between 1500 and 1400 deg C. Protoenstatite crystallizes at temperatures higher than 1350-1200 deg C; it later inverts to clinoenstatite in the 1250-1200 deg C range. Enstatite is surrounded by pigeonitic or (less frequently) augitic rims; the minimal crystallization temperature for the rims is 1000 C; high pigeonite later inverts to low pigeonite, between 935 and 845 deg C. The outer pigeonitic or augitic rims are constantly exsolved, producing sigmoidal augite or enstatite precipitates; sigmoidal precipitates record exsolution temperatures between 1000 and 640 deg C. Cooling rate (determined using the speedometer based upon ortho-clinoenstatite intergrowth) was in the order of 50-3000 deg C/h at the clinoenstatite-orthoenstatite transition temperature (close to 1250-1200 deg C), but decreased to 5-10 deg C/h or slower at the exsolution temperature (between 1000 and 650 deg C), thus revealing nonlinear cooling paths. Nanoscale observations indicate that the individual chondrules formed and cooled separately from 1500 deg down to at least 650 deg C. Accretion into chondritic parent body occurred at temperatures lower than 650 deg C.
NASA Astrophysics Data System (ADS)
Yeung, Ping Fai
1995-01-01
An improved understanding of a-Si:H pin solar cells stability was obtained by studying light induced degradation in a-Si:H films and in devices. The current -voltage characteristics and the quantum efficiencies of a-Si:H pin solar cells were measured as a function of intrinsic layer thickness, bias light intensity and degradation condition. Photoconductivity measurements on device quality intrinsic a-Si:H thin film materials showed that the majority carrier (electron) mutau product degraded from 3times 10^{-7}rm cm ^2/V to 2times 10^{ -7}rm cm^2/V after 6 minutes of 50-Suns light illumination. Using a dual beam technique with steady white light and modulated monochromatic light, a degradation profile was detected in the degraded materials. These results suggest that inhomogeneous degradation may be important to understanding the stability of a-Si:H pin solar cells. An analytical model was developed for degradation in a-Si:H pin solar cells based on inhomogeneous degradation, which was used to explain the 'blue-dip' effect observed in the quantum efficiencies of degraded cells. A new method was developed to investigate the minority carrier (hole) diffusion length in device quality a-Si:H films as a function of degradation. This method uses the Schottky barrier structure to establish a depletion region, which can be controlled by the applied voltage and the bias light intensity. Modulated blue light is used to generate electron hole pairs near the ohmic contacts, and the holes diffuse across the neutral region to be collected. The modulated current is related to the diffusion length of the holes due to this current limiting hole transport. Comparing the results of this new technique to that of the Photocarrier Grating method, the electron drift mobility was found to degrade from rm 2.5cm^2/Vs to rm 0.15cm^2/Vs after 6 minutes of 50-Suns degradation.
Mahakrishnan, Sathiya; Chakraborty, Subrata; Vijay, Amrendra
2016-09-15
Diffusion, an emergent nonequilibrium transport phenomenon, is a nontrivial manifestation of the correlation between the microscopic dynamics of individual molecules and their statistical behavior observed in experiments. We present a thorough investigation of this viewpoint using the mathematical tools of quantum scattering, within the framework of Boltzmann transport theory. In particular, we ask: (a) How and when does a normal diffusive transport become anomalous? (b) What physical attribute of the system is conceptually useful to faithfully rationalize large variations in the coefficient of normal diffusion, observed particularly within the dynamical environment of biological cells? To characterize the diffusive transport, we introduce, analogous to continuous phase transitions, the curvature of the mean square displacement as an order parameter and use the notion of quantum scattering length, which measures the effective interactions between the diffusing molecules and the surrounding, to define a tuning variable, η. We show that the curvature signature conveniently differentiates the normal diffusion regime from the superdiffusion and subdiffusion regimes and the critical point, η = ηc, unambiguously determines the coefficient of normal diffusion. To solve the Boltzmann equation analytically, we use a quantum mechanical expression for the scattering amplitude in the Boltzmann collision term and obtain a general expression for the effective linear collision operator, useful for a variety of transport studies. We also demonstrate that the scattering length is a useful dynamical characteristic to rationalize experimental observations on diffusive transport in complex systems. We assess the numerical accuracy of the present work with representative experimental results on diffusion processes in biological systems. Furthermore, we advance the idea of temperature-dependent effective voltage (of the order of 1 μV or less in a biological environment, for example
DoE optimization of a mercury isotope ratio determination method for environmental studies.
Berni, Alex; Baschieri, Carlo; Covelli, Stefano; Emili, Andrea; Marchetti, Andrea; Manzini, Daniela; Berto, Daniela; Rampazzo, Federico
2016-05-15
By using the experimental design (DoE) technique, we optimized an analytical method for the determination of mercury isotope ratios by means of cold-vapor multicollector ICP-MS (CV-MC-ICP-MS) to provide absolute Hg isotopic ratio measurements with a suitable internal precision. By running 32 experiments, the influence of mercury and thallium internal standard concentrations, total measuring time and sample flow rate was evaluated. Method was optimized varying Hg concentration between 2 and 20 ng g(-1). The model finds out some correlations within the parameters affect the measurements precision and predicts suitable sample measurement precisions for Hg concentrations from 5 ng g(-1) Hg upwards. The method was successfully applied to samples of Manila clams (Ruditapes philippinarum) coming from the Marano and Grado lagoon (NE Italy), a coastal environment affected by long term mercury contamination mainly due to mining activity. Results show different extents of both mass dependent fractionation (MDF) and mass independent fractionation (MIF) phenomena in clams according to their size and sampling sites in the lagoon. The method is fit for determinations on real samples, allowing for the use of Hg isotopic ratios to study mercury biogeochemical cycles in complex ecosystems. PMID:26992509
Analytical study of the hydrogen-air reaction mechanism with application to scramjet combustion
Jachimowski, C.J.
1988-02-01
A chemical kinetic mechanism for the combustion of hydrogen has been assembled and optimized by comparing the observed behavior as determined in shock tube and flame studies with that predicted by the mechanism. The reactions contained in the mechanism reflect the current state of knowledge of the chemistry of the hydrogen/air system, and the assigned rate coefficients are consistent with accepted values. It was determined that the mechanism is capable of satisfactorily reproducing the experimental results for a range of conditions relevant to scramjet combustion. Calculations made with the reaction mechanism for representative scramjet combustor conditions at Mach 8, 16, and 25 showed that chemical kinetic effects can be important and that combustor models which use nonequilibrium chemistry should be used in preference to models that assume equilibrium chemistry. For the conditions examined the results also showed the importance of including the HO/sub 2/ chemistry in the mechanism. For Mach numbers less than 16, the studies suggest that an ignition source will most likely be required to overcome slow ignition chemistry. At Mach 25, the initial temperature and pressure was high enough that ignition was rapid and the presence of an ignition source did not significantly affect reaction rates.
An analytical study of the hydrogen-air reaction mechanism with application to scramjet combustion
NASA Technical Reports Server (NTRS)
Jachimowski, Casimir J.
1988-01-01
A chemical kinetic mechanism for the combustion of hydrogen has been assembled and optimized by comparing the observed behavior as determined in shock tube and flame studies with that predicted by the mechanism. The reactions contained in the mechanism reflect the current state of knowledge of the chemistry of the hydrogen/air system, and the assigned rate coefficients are consistent with accepted values. It was determined that the mechanism is capable of satisfactorily reproducing the experimental results for a range of conditions relevant to scramjet combustion. Calculations made with the reaction mechanism for representative scramjet combustor conditions at Mach 8, 16, and 25 showed that chemical kinetic effects can be important and that combustor models which use nonequilibrium chemistry should be used in preference to models that assume equilibrium chemistry. For the conditions examined the results also showed the importance of including the HO2 chemistry in the mechanism. For Mach numbers less than 16, the studies suggest that an ignition source will most likely be required to overcome slow ignition chemistry. At Mach 25, the initial temperature and pressure was high enough that ignition was rapid and the presence of an ignition source did not significantly affect reaction rates.
Han, Yafeng; Shen, Bo; Hu, Huajin; Fan, Fei
2015-01-12
Ice-storage air-conditioning is a technique that uses ice for thermal energy storage. Replacing existing air conditioning systems with ice storage has the advantage of shifting the load from on-peak times to off-peak times that often have excess generation. However, increasing the use of ice-storage faces significant challenges in China. One major barrier is the inefficiency in the current electricity tariff structure. There is a lack of effective incentive mechanism that induces ice-storage systems from achieving optimal load-shifting results. This study presents an analysis that compares the potential impacts of ice-storage systems on load-shifting under a new credit-based incentive scheme and the existing incentive arrangement in Jiangsu, China. The study indicates that by changing how ice-storage systems are incentivized in Jiangsu, load-shifting results can be improved.
Han, Yafeng; Shen, Bo; Hu, Huajin; Fan, Fei
2015-01-12
Ice-storage air-conditioning is a technique that uses ice for thermal energy storage. Replacing existing air conditioning systems with ice storage has the advantage of shifting the load from on-peak times to off-peak times that often have excess generation. However, increasing the use of ice-storage faces significant challenges in China. One major barrier is the inefficiency in the current electricity tariff structure. There is a lack of effective incentive mechanism that induces ice-storage systems from achieving optimal load-shifting results. This study presents an analysis that compares the potential impacts of ice-storage systems on load-shifting under a new credit-based incentive scheme andmore » the existing incentive arrangement in Jiangsu, China. The study indicates that by changing how ice-storage systems are incentivized in Jiangsu, load-shifting results can be improved.« less
Optimists or optimistic? A taxometric study of optimism.
Eichner, Katherine V; Kwon, Paul; Marcus, David K
2014-09-01
Although most researchers have assumed that optimism exists on a continuum, it is not uncommon for researchers to dichotomize their data into optimists and pessimists, thus treating optimism as a categorical or taxonic variable. To address the question of whether optimism is dimensional or taxonic, the authors performed a set of taxometric analyses on 3 indicators derived from measures of hope and optimism using data from 510 college students. The results provided consistent evidence that optimism is dimensional. Colloquially, people may speak of optimists and pessimists, but researchers should avoid dichotomizing this continuous variable.
The Efficiency of South African Universities: A Study Based on the Analytical Review Technique.
ERIC Educational Resources Information Center
Taylor, B.; Harris, G.
2002-01-01
Examined the relative efficiency of 10 South African universities between 1994 and 1997 using the analytical review technique. Identified the relatively efficient, relatively inefficient, and least efficient. Important efficiency factors include student population dimensions, quality and deployment of personnel resources, and allocation of…
Knowledge, Skills, and Abilities for Entry-Level Business Analytics Positions: A Multi-Method Study
ERIC Educational Resources Information Center
Cegielski, Casey G.; Jones-Farmer, L. Allison
2016-01-01
It is impossible to deny the significant impact from the emergence of big data and business analytics on the fields of Information Technology, Quantitative Methods, and the Decision Sciences. Both industry and academia seek to hire talent in these areas with the hope of developing organizational competencies. This article describes a multi-method…
21 CFR 320.29 - Analytical methods for an in vivo bioavailability or bioequivalence study.
Code of Federal Regulations, 2014 CFR
2014-04-01
... ingredient or therapeutic moiety, or its active metabolite(s), in body fluids or excretory products, or the... ingredient or therapeutic moiety, or its active metabolite(s), achieved in the body. (b) When the analytical... therapeutic moiety, or its active metabolite(s), in body fluids or excretory products produced by a...
21 CFR 320.29 - Analytical methods for an in vivo bioavailability or bioequivalence study.
Code of Federal Regulations, 2012 CFR
2012-04-01
... ingredient or therapeutic moiety, or its active metabolite(s), in body fluids or excretory products, or the... ingredient or therapeutic moiety, or its active metabolite(s), achieved in the body. (b) When the analytical... therapeutic moiety, or its active metabolite(s), in body fluids or excretory products produced by a...
21 CFR 320.29 - Analytical methods for an in vivo bioavailability or bioequivalence study.
Code of Federal Regulations, 2013 CFR
2013-04-01
... ingredient or therapeutic moiety, or its active metabolite(s), in body fluids or excretory products, or the... ingredient or therapeutic moiety, or its active metabolite(s), achieved in the body. (b) When the analytical... therapeutic moiety, or its active metabolite(s), in body fluids or excretory products produced by a...
21 CFR 320.29 - Analytical methods for an in vivo bioavailability or bioequivalence study.
Code of Federal Regulations, 2011 CFR
2011-04-01
... ingredient or therapeutic moiety, or its active metabolite(s), in body fluids or excretory products, or the... ingredient or therapeutic moiety, or its active metabolite(s), achieved in the body. (b) When the analytical... therapeutic moiety, or its active metabolite(s), in body fluids or excretory products produced by a...
21 CFR 320.29 - Analytical methods for an in vivo bioavailability or bioequivalence study.
Code of Federal Regulations, 2010 CFR
2010-04-01
... ingredient or therapeutic moiety, or its active metabolite(s), in body fluids or excretory products, or the... ingredient or therapeutic moiety, or its active metabolite(s), achieved in the body. (b) When the analytical... therapeutic moiety, or its active metabolite(s), in body fluids or excretory products produced by a...
ERIC Educational Resources Information Center
Groh, Ashley M.; Roisman, Glenn I.; van IJzendoorn, Marinus H.; Bakermans-Kranenburg, Marian J.; Fearon, R. Pasco
2012-01-01
This meta-analytic review examines the association between attachment and internalizing symptomatology during childhood, and compares the strength of this association with that for externalizing symptomatology. Based on 42 independent samples (N = 4,614), the association between insecurity and internalizing symptoms was small, yet significant (d =…
A Descriptive-Analytic Study of the Practice Field Behavior of a Winning Female Coach.
ERIC Educational Resources Information Center
Dodds, Patt; Rife, Frank
A winning collegiate field hockey coach was observed across seventeen practice sessions through one complete competitive season. A category system for the event recording of verbal and nonverbal behaviors delivered to the team and to the sixteen individual players produced descriptive-analytic information about relative behavior frequencies for…
Study on Two Methods for Nonlinear Force-Free Extrapolation Based on Semi-Analytical Field
NASA Astrophysics Data System (ADS)
Liu, S.; Zhang, H. Q.; Su, J. T.; Song, M. T.
2011-03-01
In this paper, two semi-analytical solutions of force-free fields (Low and Lou, Astrophys. J. 352, 343, 1990) have been used to test two nonlinear force-free extrapolation methods. One is the boundary integral equation (BIE) method developed by Yan and Sakurai ( Solar Phys. 195, 89, 2000), and the other is the approximate vertical integration (AVI) method developed by Song et al. ( Astrophys. J. 649, 1084, 2006). Some improvements have been made to the AVI method to avoid the singular points in the process of calculation. It is found that the correlation coefficients between the first semi-analytical field and extrapolated field using the BIE method, and also that obtained by the improved AVI method, are greater than 90% below a height 10 of the 64×64 lower boundary. For the second semi-analytical field, these correlation coefficients are greater than 80% below the same relative height. Although differences between the semi-analytical solutions and the extrapolated fields exist for both the BIE and AVI methods, these two methods can give reliable results for heights of about 15% of the extent of the lower boundary.
A Multidimensional Reappraisal of Language in Autism: Insights from a Discourse Analytic Study
ERIC Educational Resources Information Center
Sterponi, Laura; de Kirby, Kenton
2016-01-01
In this article, we leverage theoretical insights and methodological guidelines of discourse analytic scholarship to re-examine language phenomena typically associated with autism. Through empirical analysis of the verbal behavior of three children with autism, we engage the question of how prototypical features of autistic language--notably…
Planning, evaluation and analytical studies in planetary quarantine and spacecraft sterilization
NASA Technical Reports Server (NTRS)
1972-01-01
The technical and analytical support used to aid in developing requirements for planetary quarantine are presented. The investigation was divided into 8 work tasks which are presented in tabular form. Data include methods of sterilization, safety margins for quarantine, revision of contamination logs for Mars and Venus, and estimates of encapsulated and 'free' microbial burden.
Juicing the Juice: A Laboratory-Based Case Study for an Instrumental Analytical Chemistry Course
ERIC Educational Resources Information Center
Schaber, Peter M.; Dinan, Frank J.; St. Phillips, Michael; Larson, Renee; Pines, Harvey A.; Larkin, Judith E.
2011-01-01
A young, inexperienced Food and Drug Administration (FDA) chemist is asked to distinguish between authentic fresh orange juice and suspected reconstituted orange juice falsely labeled as fresh. In an advanced instrumental analytical chemistry application of this case, inductively coupled plasma (ICP) spectroscopy is used to distinguish between the…
Learning Analytics: A Case Study of the Process of Design of Visualizations
ERIC Educational Resources Information Center
Olmos, Martin; Corrin, Linda
2012-01-01
The ability to visualize student engagement and experience data provides valuable opportunities for learning support and curriculum design. With the rise of the use of learning analytics to provide "actionable intelligence" on students' learning, the challenge is to create visualizations of the data, which are clear and useful to the intended…
Performance Trades Study for Robust Airfoil Shape Optimization
NASA Technical Reports Server (NTRS)
Li, Wu; Padula, Sharon
2003-01-01
From time to time, existing aircraft need to be redesigned for new missions with modified operating conditions such as required lift or cruise speed. This research is motivated by the needs of conceptual and preliminary design teams for smooth airfoil shapes that are similar to the baseline design but have improved drag performance over a range of flight conditions. The proposed modified profile optimization method (MPOM) modifies a large number of design variables to search for nonintuitive performance improvements, while avoiding off-design performance degradation. Given a good initial design, the MPOM generates fairly smooth airfoils that are better than the baseline without making drastic shape changes. Moreover, the MPOM allows users to gain valuable information by exploring performance trades over various design conditions. Four simulation cases of airfoil optimization in transonic viscous ow are included to demonstrate the usefulness of the MPOM as a performance trades study tool. Simulation results are obtained by solving fully turbulent Navier-Stokes equations and the corresponding discrete adjoint equations using an unstructured grid computational fluid dynamics code FUN2D.
Second-generation-heliostat optimization studies. Final report
Not Available
1982-05-01
The objective of this study was to define and quantify cost reductions in the Martin Marietta Denver Aerospace Second Generation Heliostat resulting from design and cost optimization. These cost reductions were based on optimizing the heliostat performance vs. cost and engineering design, and reviewing the design specification in selected technological areas with a goal of removing nonrealistic requirements and eliminating or minimizing overdesign. Specific technological areas investigated were: (1) designing the heliostat for survival strength rather than stiffness and reducing the operational wind requirements as dictated by this design approach; (2) reducing the pointing accuracy and/or beam quality required for some fraction or all of the heliostat field; (3) modifying the operational temperature range; (4) relaxing the rate at which the heliostat must move in the slew mode; (5) using alternate beam safety strategies; (6) analyzing actual wind data for selected sites in the southwest United States vs. the heliostat design specification survival wind requirements; (7) estimating heliostat damage for winds in excess of the design specification over a 30 year period; (8) evaluating the impact of designing the heliostat for higher wind loads; and (9) investigating the applicability to heliostat design of the standard engineering practices for designing buildings.
Flatland, Bente; Friedrichs, Kristen R; Klenner, Stefanie
2014-12-01
Prior to introduction of a new method to the diagnostic laboratory, analytical performance must be validated to ensure operation within the manufacturer's specifications and/or within predetermined quality requirements. In addition, the new method may require diagnostic performance assessment to ensure it differentiates between diseased and nondiseased individuals as intended. These 2 phases of assessment, while complementary, are not equivalent and require a different set of experiments, statistical analyses, and interpretation. Studies of analytical performance typically include a method comparison experiment, the purpose of which is to identify bias (inaccuracy) of the "test" (or "index") method (new method) relative to a "comparative method" (established method). Analysis of method comparison data is facilitated by commercial software programs that present the statistical significance of identified bias; however, the clinical relevance of any bias also should be considered. Studies of diagnostic performance should not be pursued until analytical performance is fully characterized and may not be required for well-established tests or for those for which results are nonspecific (ie, not referable to a specific disease or condition). Diagnostic performance assessment may include assessment of sensitivity, specificity, predictive values, odds ratios, and/or likelihood ratios. The purpose of this review is to clarify differences between the assessment of analytical and diagnostic performance, and to explore the method comparison study and bias assessment from a perspective not addressed in prior veterinary articles.
NASA Technical Reports Server (NTRS)
Torres-Pomales, Wilfredo
2015-01-01
This report documents a case study on the application of Reliability Engineering techniques to achieve an optimal balance between performance and robustness by tuning the functional parameters of a complex non-linear control system. For complex systems with intricate and non-linear patterns of interaction between system components, analytical derivation of a mathematical model of system performance and robustness in terms of functional parameters may not be feasible or cost-effective. The demonstrated approach is simple, structured, effective, repeatable, and cost and time efficient. This general approach is suitable for a wide range of systems.
Hybrid vehicle system studies and optimized hydrogen engine design
NASA Astrophysics Data System (ADS)
Smith, J. R.; Aceves, S.
1995-04-01
We have done system studies of series hydrogen hybrid automobiles that approach the PNGV design goal of 34 km/liter (80 mpg), for 384 km (240 mi) and 608 km (380 mi) ranges. Our results indicate that such a vehicle appears feasible using an optimized hydrogen engine. We have evaluated the impact of various on-board storage options on fuel economy. Experiments in an available engine at the Sandia CRF demonstrated NO(x) emissions of 10 to 20 ppM at an equivalence ratio of 0.4, rising to about 500 ppm at 0.5 equivalence ratio using neat hydrogen. Hybrid simulation studies indicate that exhaust NO(x) concentrations must be less than 180 ppM to meet the 0.2 g/mile ULEV or Federal Tier II emissions regulations. LLNL has designed and fabricated a first generation optimized hydrogen engine head for use on an existing Onan engine. This head features 15:1 compression ratio, dual ignition, water cooling, two valves and open quiescent combustion chamber to minimize heat transfer losses. Initial testing shows promise of achieving an indicated efficiency of nearly 50% and emissions of less than 100 ppM NO(x). Hydrocarbons and CO are to be measured, but are expected to be very low since their only source is engine lubricating oil. A successful friction reduction program on the Onan engine should result in a brake thermal efficiency of about 42% compared to today's gasoline engines of 32%. Based on system studies requirements, the next generation engine will be about 2 liter displacement and is projected to achieve 46% brake thermal efficiency with outputs of 15 kW for cruise and 40 kW for hill climb.
Analytical and numerical study of the thermal feedback in Groundwater Heat Pumps (GWHP)
NASA Astrophysics Data System (ADS)
Casasso, Alessandro; Sethi, Rajandrea
2014-05-01
Ground Water Heat Pumps (GWHP) are a promising renewable heating and cooling technology, which can noticeably reduce primary energy consumption of air conditioning in buildings. To ensure their efficiency and sustainability over time, hydrogeological modelling is of pivotal importance, since thermal feedback between injection and extraction well can heavily impair their performances. On the other hand, an accurate numerical flow and heat transport simulation is not usually performed and is not affordable on small installations. The aim of this study is to solve the hydraulic and thermal transport problem of an injection and an extraction well, in presence of a subsurface flow, by means of a finite-difference approximation of the potential flow theory. The results of this approach have been firstly validated against FEM numerical simulation showing a good agreement in a wide a range of operating conditions, then used in order to develop an approximated analytical relationship which describes the evolution of the thermal feedback over time. The relationship is dependent on the most relevant parameters of the aquifer system and of the GWHP and it can be effectively used for a fast dimensioning of full scale installations. References Ampofo F., Maidment G.G., Missenden J.F., 2006, Review of groundwater cooling systems in London, Applied Thermal Engineering 26, pp. 2055-2062 Brashears M.L., 1941, Ground-water temperature on Long Island, New York, as affected by recharge of warm water, Economic Geology 36, pp. 811-828 Clyde C.G., Madabhushi G.V., 1983, Spacing of wells for heat pumps, Journal of Water Resources Planning & Management - ASCE 109, pp. 203-212 Ferguson G., 2006, Potential use of particle tracking in the analysis of low-temperature geothermal developments, Geothermics 35, pp. 44-58 Gringarten A.C., Sauty J.P., 1975, A theoretical study of heat extraction from aquifers with uniform regional flow, Journal of Geophysical Research 80, pp. 4956-4962 Lippmann M
Novel Visual and Analytical Methods in Repurposing Legacy Scientific Code - A Case Study
Oehmen, Christopher S.; Curtis, Darren S.; Phillips, Aaron R.; Peterson, Elena S.
2013-07-23
Scientific computing is dominated by team-authored legacy code that has evolved over decades with the purpose of capturing the evolving understanding of a scientific discipline. Accumulated deprecated code, various optimization techniques, and evolving algorithms lead to convoluted source code that is impractical to reverse engineer using mainstream methods. This prevents codes from being truly repeatable or understandable, which are two of the most essential needs in scientific computing. We refactored a long-standing implementation of a common biosequence alignment algorithm in an effort to reproduce its salient behaviors in usable form. Because of the sheer size and complexity of this code base, we developed custom tools to visualize and manipulate the source code behavior under a variety of conditions. We present a case study of extracting and refactoring the algorithmic core and a novel process of discovery/prototyping/testing using a combination of openly available and custom-built tools. The result is a reduction in code size of over 2 orders of magnitude while reconstructing the key protein alignment function in BLAST
Bonaduce, Ilaria; Ribechini, Erika; Modugno, Francesca; Colombini, Maria Perla
2016-02-01
Gas chromatography/mass spectrometry (GC/MS), after appropriate wet chemical sample pre-treatments or pyrolysis, is one of the most commonly adopted analytical techniques in the study of organic materials from cultural heritage objects. Organic materials in archaeological contexts, in classical art objects, or in modern and contemporary works of art may be the same or belong to the same classes, but can also vary considerably, often presenting different ageing pathways and chemical environments. This paper provides an overview of the literature published in the last 10 years on the research based on the use of GC/MS for the analysis of organic materials in artworks and archaeological objects. The latest progresses in advancing analytical approaches, characterising materials and understanding their degradation, and developing methods for monitoring their stability are discussed. Case studies from the literature are presented to examine how the choice of the working conditions and the analytical approaches is driven by the analytical and technical question to be answered, as well as the nature of the object from which the samples are collected. PMID:27572989
Bonaduce, Ilaria; Ribechini, Erika; Modugno, Francesca; Colombini, Maria Perla
2016-02-01
Gas chromatography/mass spectrometry (GC/MS), after appropriate wet chemical sample pre-treatments or pyrolysis, is one of the most commonly adopted analytical techniques in the study of organic materials from cultural heritage objects. Organic materials in archaeological contexts, in classical art objects, or in modern and contemporary works of art may be the same or belong to the same classes, but can also vary considerably, often presenting different ageing pathways and chemical environments. This paper provides an overview of the literature published in the last 10 years on the research based on the use of GC/MS for the analysis of organic materials in artworks and archaeological objects. The latest progresses in advancing analytical approaches, characterising materials and understanding their degradation, and developing methods for monitoring their stability are discussed. Case studies from the literature are presented to examine how the choice of the working conditions and the analytical approaches is driven by the analytical and technical question to be answered, as well as the nature of the object from which the samples are collected.
Performance Study and Dynamic Optimization Design for Thread Pool Systems
Dongping Xu
2004-12-19
Thread pools have been widely used by many multithreaded applications. However, the determination of the pool size according to the application behavior still remains problematic. To automate this process, in this thesis we have developed a set of performance metrics for quantitatively analyzing thread pool performance. For our experiments, we built a thread pool system which provides a general framework for thread pool research. Based on this simulation environment, we studied the performance impact brought by the thread pool on different multithreaded applications. Additionally, the correlations between internal characterizations of thread pools and their throughput were also examined. We then proposed and evaluated a heuristic algorithm to dynamically determine the optimal thread pool size. The simulation results show that this approach is effective in improving overall application performance.
Study of information transfer optimization for communication satellites
NASA Technical Reports Server (NTRS)
Odenwalder, J. P.; Viterbi, A. J.; Jacobs, I. M.; Heller, J. A.
1973-01-01
The results are presented of a study of source coding, modulation/channel coding, and systems techniques for application to teleconferencing over high data rate digital communication satellite links. Simultaneous transmission of video, voice, data, and/or graphics is possible in various teleconferencing modes and one-way, two-way, and broadcast modes are considered. A satellite channel model including filters, limiter, a TWT, detectors, and an optimized equalizer is treated in detail. A complete analysis is presented for one set of system assumptions which exclude nonlinear gain and phase distortion in the TWT. Modulation, demodulation, and channel coding are considered, based on an additive white Gaussian noise channel model which is an idealization of an equalized channel. Source coding with emphasis on video data compression is reviewed, and the experimental facility utilized to test promising techniques is fully described.