972 resultados para Heurística surrogate
Resumo:
Los protocolos de medición antropométrica se caracterizan por la profusión de medidas discretas o localizadas, en un intento para caracterizar completamente la forma corporal del sujeto -- Dichos protocolos se utilizan intensivamente en campos como medicina deportiva, forense y/o reconstructiva, diseño de prótesis, ergonomía, en la confección de prendas, accesorios, etc -- Con el avance de algoritmos de recuperación de formas a partir de muestreos (digitalizaciones) la caracterización antropométrica se ha alterado significativamente -- El articulo presente muestra el proceso de caracterización digital de forma corpórea, incluyendo los protocolos de medición sobre el sujeto, el ambiente computacional - DigitLAB- (desarrollado en el CII-CAD-CAM-CG de la Universidad EAFIT) para recuperación de superficies, hasta los modelos geométricos finales -- Se presentan comparaciones de los resultados obtenidos con DigitLAB y con paquetes comerciales de recuperación de forma 3D -- Los resultados de DigitLAB resultan superiores, debido principalmente al hecho de que este toma ventaja de los patrones de las digitalizaciones (planares de contacto, por rejilla de pixels - range images -, etc.) y provee módulos de tratamiento geométrico - estadístico de los datos para poder aplicar efectivamente los algoritmos de recuperación de forma -- Se presenta un caso de estudio dirigido a la industria de la confección, y otros efectuados sobre conjuntos de prueba comunes en el ámbito científico para la homologación de algoritmos
Resumo:
This thesis studies mobile robotic manipulators, where one or more robot manipulator arms are integrated with a mobile robotic base. The base could be a wheeled or tracked vehicle, or it might be a multi-limbed locomotor. As robots are increasingly deployed in complex and unstructured environments, the need for mobile manipulation increases. Mobile robotic assistants have the potential to revolutionize human lives in a large variety of settings including home, industrial and outdoor environments.
Mobile Manipulation is the use or study of such mobile robots as they interact with physical objects in their environment. As compared to fixed base manipulators, mobile manipulators can take advantage of the base mechanism’s added degrees of freedom in the task planning and execution process. But their use also poses new problems in the analysis and control of base system stability, and the planning of coordinated base and arm motions. For mobile manipulators to be successfully and efficiently used, a thorough understanding of their kinematics, stability, and capabilities is required. Moreover, because mobile manipulators typically possess a large number of actuators, new and efficient methods to coordinate their large numbers of degrees of freedom are needed to make them practically deployable. This thesis develops new kinematic and stability analyses of mobile manipulation, and new algorithms to efficiently plan their motions.
I first develop detailed and novel descriptions of the kinematics governing the operation of multi- limbed legged robots working in the presence of gravity, and whose limbs may also be simultaneously used for manipulation. The fundamental stance constraint that arises from simple assumptions about friction and the ground contact and feasible motions is derived. Thereafter, a local relationship between joint motions and motions of the robot abdomen and reaching limbs is developed. Baseeon these relationships, one can define and analyze local kinematic qualities including limberness, wrench resistance and local dexterity. While previous researchers have noted the similarity between multi- fingered grasping and quasi-static manipulation, this thesis makes explicit connections between these two problems.
The kinematic expressions form the basis for a local motion planning problem that that determines the joint motions to achieve several simultaneous objectives while maintaining stance stability in the presence of gravity. This problem is translated into a convex quadratic program entitled the balanced priority solution, whose existence and uniqueness properties are developed. This problem is related in spirit to the classical redundancy resoxlution and task-priority approaches. With some simple modifications, this local planning and optimization problem can be extended to handle a large variety of goals and constraints that arise in mobile-manipulation. This local planning problem applies readily to other mobile bases including wheeled and articulated bases. This thesis describes the use of the local planning techniques to generate global plans, as well as for use within a feedback loop. The work in this thesis is motivated in part by many practical tasks involving the Surrogate and RoboSimian robots at NASA/JPL, and a large number of examples involving the two robots, both real and simulated, are provided.
Finally, this thesis provides an analysis of simultaneous force and motion control for multi- limbed legged robots. Starting with a classical linear stiffness relationship, an analysis of this problem for multiple point contacts is described. The local velocity planning problem is extended to include generation of forces, as well as to maintain stability using force-feedback. This thesis also provides a concise, novel definition of static stability, and proves some conditions under which it is satisfied.
Resumo:
Heart rate asymmetry (HRA) is considered as a physiological phenomenon in healthy subjects. In this article, we propose a novel HRA index, Slope Index (SI), to quantify phase asymmetry of heart rate variability (HRV) system. We assessed the performance of proposed index in comparison with conventional (Guzik's Index (GI) and Porta's Index (PI)) HRA indices. As illustrative examples, we used two case studies: (i) differentiate physiologic RR series from synthetic RR series; and (ii) discriminate arrhythmia subjects from Healthy using beat-to-beat heart rate time series. The results showed that SI is a superior parameter than GI and PI for both case studies with maximum ROC area of 0.84 and 0.82 respectively. In contrast, GI and PI had ROC areas {0.78, 0.61} and {0.50, 0.56} in two case studies respectively. We also performed surrogate analysis to show that phase asymmetry is caused by a physiologic phenomena rather than a random nature of the signal. In conclusion, quantification of phase asymmetry of HRV provides additional information on HRA, which might have a potential clinical use to discriminate pathological HRV in future.
Resumo:
OBJECTIVES: To describe changes in the use of intravenous (IV) fluid by quantity and type in different regions of Australia and New Zealand. DESIGN, SETTING AND PARTICIPANTS: We conducted a retrospective ecological study examining regional and temporal trends in IV fluid consumption across Australia and New Zealand over the periods 2012-2013 and 2013- 2014, using national proprietary sales data as a surrogate for consumption, and demographic data from the public domain. RESULTS: More than 13.3 million litres of IV fluid were consumed in Australia and New Zealand in 2012-2013, and more than 13.9 million litres in 2013-2014, with colloid solutions accounting for < 2%. There was marked regional variation in consumption of fluids, by volumes and proportions used, when standardised to overall Australian and New Zealand values. There was no significant change in the overall volume of crystalloid solutions consumed but there was a significant decrease (9%; P = 0.02) in the ratio of unbalanced to balanced crystalloid solutions consumed. Consumption of all forms of colloid solutions decreased, with a 12% reduction overall (P = 0.02), primarily driven by a 67% reduction in the consumption of hydroxyethyl starch (HES) solutions. CONCLUSIONS: The amount and type of IV fluid use, as determined by fluid sales, is highly variable across Australia and New Zealand. However, overall use of balanced crystalloid solutions is increasing and the use of HES has decreased dramatically.
Resumo:
A NOx reduction efficiency higher than 95% with NH3 slip less than 30 ppm is desirable for heavy-duty diesel (HDD) engines using selective catalytic reduction (SCR) systems to meet the US EPA 2010 NOx standard and the 2014-2018 fuel consumption regulation. The SCR performance needs to be improved through experimental and modeling studies. In this research, a high fidelity global kinetic 1-dimensional 2-site SCR model with mass transfer, heat transfer and global reaction mechanisms was developed for a Cu-zeolite catalyst. The model simulates the SCR performance for the engine exhaust conditions with NH3 maldistribution and aging effects, and the details are presented. SCR experimental data were collected for the model development, calibration and validation from a reactor at Oak Ridge National Laboratory (ORNL) and an engine experimental setup at Michigan Technological University (MTU) with a Cummins 2010 ISB engine. The model was calibrated separately to the reactor and engine data. The experimental setup, test procedures including a surrogate HD-FTP cycle developed for transient studies and the model calibration process are described. Differences in the model parameters were determined between the calibrations developed from the reactor and the engine data. It was determined that the SCR inlet NH3 maldistribution is one of the reasons causing the differences. The model calibrated to the engine data served as a basis for developing a reduced order SCR estimator model. The effect of the SCR inlet NO2/NOx ratio on the SCR performance was studied through simulations using the surrogate HD-FTP cycle. The cumulative outlet NOx and the overall NOx conversion efficiency of the cycle are highest with a NO2/NOx ratio of 0.5. The outlet NH3 is lowest for the NO2/NOx ratio greater than 0.6. A combined engine experimental and simulation study was performed to quantify the NH3 maldistribution at the SCR inlet and its effects on the SCR performance and kinetics. The uniformity index (UI) of the SCR inlet NH3 and NH3/NOx ratio (ANR) was determined to be below 0.8 for the production system. The UI was improved to 0.9 after installation of a swirl mixer into the SCR inlet cone. A multi-channel model was developed to simulate the maldistribution effects. The results showed that reducing the UI of the inlet ANR from 1.0 to 0.7 caused a 5-10% decrease in NOx reduction efficiency and 10-20 ppm increase in the NH3 slip. The simulations of the steady-state engine data with the multi-channel model showed that the NH3 maldistribution is a factor causing the differences in the calibrations developed from the engine and the reactor data. The Reactor experiments were performed at ORNL using a Spaci-IR technique to study the thermal aging effects. The test results showed that the thermal aging (at 800°C for 16 hours) caused a 30% reduction in the NH3 stored on the catalyst under NH3 saturation conditions and different axial concentration profiles under SCR reaction conditions. The kinetics analysis showed that the thermal aging caused a reduction in total NH3 storage capacity (94.6 compared to 138 gmol/m3), different NH3 adsorption/desorption properties and a decrease in activation energy and the pre-exponential factor for NH3 oxidation, standard and fast SCR reactions. Both reduction in the storage capability and the change in kinetics of the major reactions contributed to the change in the axial storage and concentration profiles observed from the experiments.
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The United States transportation industry is predicted to consume approximately 13 million barrels of liquid fuel per day by 2025. If one percent of the fuel energy were salvaged through waste heat recovery, there would be a reduction of 130 thousand barrels of liquid fuel per day. This dissertation focuses on automotive waste heat recovery techniques with an emphasis on two novel techniques. The first technique investigated was a combination coolant and exhaust-based Rankine cycle system, which utilized a patented piston-in-piston engine technology. The research scope included a simulation of the maximum mass flow rate of steam (700 K and 5.5 MPa) from two heat exchangers, the potential power generation from the secondary piston steam chambers, and the resulting steam quality within the steam chamber. The secondary piston chamber provided supplemental steam power strokes during the engine's compression and exhaust strokes to reduce the pumping work of the engine. A Class-8 diesel engine, operating at 1,500 RPM at full load, had a maximum increase in the brake fuel conversion efficiency of 3.1%. The second technique investigated the implementation of thermoelectric generators on the outer cylinder walls of a liquid-cooled internal combustion engine. The research scope focused on the energy generation, fuel energy distribution, and cylinder wall temperatures. The analysis was conducted over a range of engine speeds and loads in a two cylinder, 19.4 kW, liquid-cooled, spark-ignition engine. The cylinder wall temperatures increased by 17% to 44% which correlated well to the 4.3% to 9.5% decrease in coolant heat transfer. Only 23.3% to 28.2% of the heat transfer to the coolant was transferred through the TEG and TEG surrogate material. The gross indicated work decreased by 0.4% to 1.0%. The exhaust gas energy decreased by 0.8% to 5.9%. Due to coolant contamination, the TEG output was not able to be obtained. TEG output was predicted from cylinder wall temperatures and manufacturer documentation, which was less than 0.1% of the cumulative heat release. Higher TEG conversion efficiencies, combined with greater control of heat transfer paths, would be needed to improve energy output and make this a viable waste heat recovery technique.
Resumo:
The International Space Station (ISS) requires a substantial amount of potable water for use by the crew. The economic and logistic limitations of transporting the vast amount of water required onboard the ISS necessitate onboard recovery and reuse of the aqueous waste streams. Various treatment technologies are employed within the ISS water processor to render the waste water potable, including filtration, ion exchange, adsorption, and catalytic wet oxidation. The ion exchange resins and adsorption media are combined in multifiltration beds for removal of ionic and organic compounds. A mathematical model (MFBMODEL™) designed to predict the performance of a multifiltration (MF) bed was developed. MFBMODEL consists of ion exchange models for describing the behavior of the different resin types in a MF bed (e.g., mixed bed, strong acid cation, strong base anion, and weak base anion exchange resins) and an adsorption model capable of predicting the performance of the adsorbents in a MF bed. Multicomponent ion exchange ii equilibrium models that incorporate the water formation reaction, electroneutrality condition, and degree of ionization of weak acids and bases for mixed bed, strong acid cation, strong base anion, and weak base anion exchange resins were developed and verified. The equilibrium models developed use a tanks-inseries approach that allows for consideration of variable influent concentrations. The adsorption modeling approach was developed in related studies and application within the MFBMODEL framework was demonstrated in the Appendix to this study. MFBMODEL consists of a graphical user interface programmed in Visual Basic and Fortran computational routines. This dissertation shows MF bed modeling results in which the model is verified for a surrogate of the ISS waste shower and handwash stream. In addition, a multicomponent ion exchange model that incorporates mass transfer effects was developed, which is capable of describing the performance of strong acid cation (SAC) and strong base anion (SBA) exchange resins, but not including reaction effects. This dissertation presents results showing the mass transfer model's capability to predict the performance of binary and multicomponent column data for SAC and SBA exchange resins. The ion exchange equilibrium and mass transfer models developed in this study are also applicable to terrestrial water treatment systems. They could be applied for removal of cations and anions from groundwater (e.g., hardness, nitrate, perchlorate) and from industrial process waters (e.g. boiler water, ultrapure water in the semiconductor industry).
Resumo:
Detection canines represent the fastest and most versatile means of illicit material detection. This research endeavor in its most simplistic form is the improvement of detection canines through training, training aids, and calibration. This study focuses on developing a universal calibration compound for which all detection canines, regardless of detection substance, can be tested daily to ensure that they are working with acceptable parameters. Surrogate continuation aids (SCAs) were developed for peroxide based explosives along with the validation of the SCAs already developed within the International Forensic Research Institute (IFRI) prototype surrogate explosives kit. Storage parameters of the SCAs were evaluated to give recommendations to the detection canine community on the best possible training aid storage solution that minimizes the likelihood of contamination. Two commonly used and accepted detection canine imprinting methods were also evaluated for the speed in which the canine is trained and their reliability. As a result of the completion of this study, SCAs have been developed for explosive detection canine use covering: peroxide based explosives, TNT based explosives, nitroglycerin based explosives, tagged explosives, plasticized explosives, and smokeless powders. Through the use of these surrogate continuation aids a more uniform and reliable system of training can be implemented in the field than is currently used today. By examining the storage parameters of the SCAs, an ideal storage system has been developed using three levels of containment for the reduction of possible contamination. The developed calibration compound will ease the growing concerns over the legality and reliability of detection canine use by detailing the daily working parameters of the canine, allowing for Daubert rules of evidence admissibility to be applied. Through canine field testing, it has been shown that the IFRI SCAs outperform other commercially available training aids on the market. Additionally, of the imprinting methods tested, no difference was found in the speed in which the canines are trained or their reliability to detect illicit materials. Therefore, if the recommendations discovered in this study are followed, the detection canine community will greatly benefit through the use of scientifically validated training techniques and training aids.
Resumo:
The purpose of this study was to determine whether there was a relationship between pressure to perform on state mandated, high-stakes tests and the rate of student escape behavior defined as the number of school suspensions and absences. The state assigned grade of a school was used as a surrogate measure of pressure with the assumption that pressure increased as the school grade decreased. Student attendance and suspension data were gathered from all 33 of the regular public high schools in Miami-Dade County Public Schools. The research questions were: Is the number of suspensions highest in the third quarter, when most FCAT preparation takes place for each of the 3 school years 2007-08 through 2009-10? How accurately does the high school’s grade predict the number of suspensions and number of absences during each of the 4 school years 2005-06 through 2008-09? The research questions were answered using repeated measures analysis of variance for research question #1 and non-linear multiple regression for research question #2. No significant difference could be found between the numbers of suspensions in each of the grading periods nor was there a relationship between the number of suspensions and school grade. A statistically significant relationship was found between student attendance and school grade. When plotted, this relationship was found to be quadratic in nature and formed a loose inverted U for each of the four years during which data were collected. This indicated that students in very high and very low performing schools had low levels of absences while those in the midlevel of the distribution of school performance (C schools) had the greatest rates of absence. Identifying a relationship between the pressures associated with high stakes testing and student escape behavior suggests that it might be useful for building administrators to reevaluate test preparation activities and procedures being used in their building and to include anxiety reducing strategies. As a relationship was found, it sets the foundation for future studies to identify whether testing related activities are impacting some students emotionally and are causing unintended consequences of testing mandates.
Resumo:
En esta tesis, analizamos la praxis política entre 1902 y 1930 poniendo en tensión el espacio bonaerense con un microcosmos: el de la localidad del interior provincial Benito Juárez. Partimos de considerar que dicha praxis se caracterizó por una multiplicidad de actuaciones (algunas conocidas, otras novedosas) dotadas de sentido y articuladas por el clientelismo político. Nuestro estudio aborda los modos en que los actores entendieron, configuraron y practicaron la política por aquellos años. En ese sentido, el clientelismo y el imaginario social en torno a la política son dos conceptos centrales de esta investigación. La tesis se estructura en tres partes: la primera, dedicada a aspectos teórico- metodológicos, está compuesta por dos capítulos en los que realizamos un bosquejo por las principales características del período y los modos en que pueden entenderse nuestros conceptos (vinculándolos a las hipótesis); damos cuenta también allí de las fuentes empleadas y la metodología. En la segunda parte nos detenemos en el juego político bonaerense. Compuesta por tres capítulos, en ella abordamos las leyes electorales provinciales vistas en perspectiva con los preceptos de la legislación reformista (desde el último tercio del siglo XIX hasta 1930) y la contribución al imaginario epocal de la Revista Argentina de Ciencias Políticas (1910-1928) y el semanario Caras y Caretas (1898-1930). En la última parte de la tesis, consideramos la vida sociopolítica en el municipio de Benito Juárez, a partir de la trayectoria de un político preeminente: Pedro Díaz Pumará. A lo largo de dos capítulos, estudiamos el imaginario social en torno a la política local, los procesos electorales, las estrategias desarrolladas por Don Pedro así como las de quienes conformaron su base social de apoyo y de quienes resistieron a su liderazgo. Finalmente, en las conclusiones sistematizamos las consideraciones de cada capítulo considerando para ello nuestra 2hipótesis heurística y las que de ella se desprenden. Planteamos la conformación del clientelismo político en actos domésticos cotidianos, el carácter bifronte de un líder frente a los asuntos provinciales y locales, la novedosa legitimidad en torno a las urnas desde 1912, la construcción de leyes que permiten accionares ya conocidos, la heterogeneidad de las bases sociales de apoyo, las lógicas de quienes se oponen a un caudillo y las estrategias desarrolladas por los participantes de la vida política
Resumo:
En esta tesis, analizamos la praxis política entre 1902 y 1930 poniendo en tensión el espacio bonaerense con un microcosmos: el de la localidad del interior provincial Benito Juárez. Partimos de considerar que dicha praxis se caracterizó por una multiplicidad de actuaciones (algunas conocidas, otras novedosas) dotadas de sentido y articuladas por el clientelismo político. Nuestro estudio aborda los modos en que los actores entendieron, configuraron y practicaron la política por aquellos años. En ese sentido, el clientelismo y el imaginario social en torno a la política son dos conceptos centrales de esta investigación. La tesis se estructura en tres partes: la primera, dedicada a aspectos teórico- metodológicos, está compuesta por dos capítulos en los que realizamos un bosquejo por las principales características del período y los modos en que pueden entenderse nuestros conceptos (vinculándolos a las hipótesis); damos cuenta también allí de las fuentes empleadas y la metodología. En la segunda parte nos detenemos en el juego político bonaerense. Compuesta por tres capítulos, en ella abordamos las leyes electorales provinciales vistas en perspectiva con los preceptos de la legislación reformista (desde el último tercio del siglo XIX hasta 1930) y la contribución al imaginario epocal de la Revista Argentina de Ciencias Políticas (1910-1928) y el semanario Caras y Caretas (1898-1930). En la última parte de la tesis, consideramos la vida sociopolítica en el municipio de Benito Juárez, a partir de la trayectoria de un político preeminente: Pedro Díaz Pumará. A lo largo de dos capítulos, estudiamos el imaginario social en torno a la política local, los procesos electorales, las estrategias desarrolladas por Don Pedro así como las de quienes conformaron su base social de apoyo y de quienes resistieron a su liderazgo. Finalmente, en las conclusiones sistematizamos las consideraciones de cada capítulo considerando para ello nuestra 2hipótesis heurística y las que de ella se desprenden. Planteamos la conformación del clientelismo político en actos domésticos cotidianos, el carácter bifronte de un líder frente a los asuntos provinciales y locales, la novedosa legitimidad en torno a las urnas desde 1912, la construcción de leyes que permiten accionares ya conocidos, la heterogeneidad de las bases sociales de apoyo, las lógicas de quienes se oponen a un caudillo y las estrategias desarrolladas por los participantes de la vida política
Resumo:
En esta tesis, analizamos la praxis política entre 1902 y 1930 poniendo en tensión el espacio bonaerense con un microcosmos: el de la localidad del interior provincial Benito Juárez. Partimos de considerar que dicha praxis se caracterizó por una multiplicidad de actuaciones (algunas conocidas, otras novedosas) dotadas de sentido y articuladas por el clientelismo político. Nuestro estudio aborda los modos en que los actores entendieron, configuraron y practicaron la política por aquellos años. En ese sentido, el clientelismo y el imaginario social en torno a la política son dos conceptos centrales de esta investigación. La tesis se estructura en tres partes: la primera, dedicada a aspectos teórico- metodológicos, está compuesta por dos capítulos en los que realizamos un bosquejo por las principales características del período y los modos en que pueden entenderse nuestros conceptos (vinculándolos a las hipótesis); damos cuenta también allí de las fuentes empleadas y la metodología. En la segunda parte nos detenemos en el juego político bonaerense. Compuesta por tres capítulos, en ella abordamos las leyes electorales provinciales vistas en perspectiva con los preceptos de la legislación reformista (desde el último tercio del siglo XIX hasta 1930) y la contribución al imaginario epocal de la Revista Argentina de Ciencias Políticas (1910-1928) y el semanario Caras y Caretas (1898-1930). En la última parte de la tesis, consideramos la vida sociopolítica en el municipio de Benito Juárez, a partir de la trayectoria de un político preeminente: Pedro Díaz Pumará. A lo largo de dos capítulos, estudiamos el imaginario social en torno a la política local, los procesos electorales, las estrategias desarrolladas por Don Pedro así como las de quienes conformaron su base social de apoyo y de quienes resistieron a su liderazgo. Finalmente, en las conclusiones sistematizamos las consideraciones de cada capítulo considerando para ello nuestra 2hipótesis heurística y las que de ella se desprenden. Planteamos la conformación del clientelismo político en actos domésticos cotidianos, el carácter bifronte de un líder frente a los asuntos provinciales y locales, la novedosa legitimidad en torno a las urnas desde 1912, la construcción de leyes que permiten accionares ya conocidos, la heterogeneidad de las bases sociales de apoyo, las lógicas de quienes se oponen a un caudillo y las estrategias desarrolladas por los participantes de la vida política
