Periodic emission of droplets from an oscillating electrified meniscus of a low-viscosity, highly conductive liquid

The generation of identical droplets of controllable size in the micrometer range is a problem of much interest owing to the numerous technological applications of such droplets. This work reports an investigation of the regime of periodic emission of droplets from an electrified oscillating meniscus of a liquid of low viscosity and high electrical conductivity attached to the end of a capillary tube, which may be used to produce droplets more than ten times smaller than the diameter of the tube. To attain this periodic microdripping regime, termed axial spray mode II by Juraschek and Röllgen [R. Juraschek and F. W. Röllgen, Int. J. Mass Spectrom. 177, 1 (1998)], liquid is continuously supplied through the tube at a given constant flow rate, while a dc voltage is applied between the tube and a nearby counter electrode. The resulting electric field induces a stress at the surface of the liquid that stretches the meniscus until, in certain ranges of voltage and flow rate, it develops a ligament that eventually detaches, forming a single droplet, in a process that repeats itself periodically. While it is being stretched, the ligament develops a conical tip that emits ultrafine droplets, but the total mass emitted is practically contained in the main droplet. In the parametrical domain studied, we find that the process depends on two main dimensionless parameters, the flow rate nondimensionalized with the diameter of the tube and the capillary time, q, and the electric Bond number BE, which is a nondimensional measure of the square of the applied voltage. The meniscus oscillation frequency made nondimensional with the capillary time, f, is of order unity for very small flow rates and tends to decrease as the inverse of the square root of q for larger values of this parameter. The product of the meniscus mean volume times the oscillation frequency is nearly constant. The characteristic length and width of the liquid ligament immediately before its detachment approximately scale as powers of the flow rate and depend only weakly on the applied voltage. The diameter of the main droplets nondimensionalized with the diameter of the tube satisfies dd≈(6/π)1/3(q/f)1/3, from mass conservation, while the electric charge of these droplets is about 1/4 of the Rayleigh charge. At the minimum flow rate compatible with the periodic regimen, the dimensionless diameter of the droplets is smaller than one-tenth, which presents a way to use electrohydrodynamic atomization to generate droplets of highly conducting liquids in the micron-size range, in marked contrast with the cone-jet electrospray whose typical droplet size is in the nanometric regime for these liquids. In contrast with other microdripping regimes where the mass is emitted upon the periodic formation of a narrow capillary jet, the present regime gives one single droplet per oscillation, except for the almost massless fine aerosol emitted in the form of an electrospray.

Quasi-a priori truncation error estimation in the DGSEM

In this paper we show how to accurately perform a quasi-a priori estimation of the truncation error of steady-state solutions computed by a discontinuous Galerkin spectral element method. We estimate the spatial truncation error using the ?-estimation procedure. While most works in the literature rely on fully time-converged solutions on grids with different spacing to perform the estimation, we use non time-converged solutions on one grid with different polynomial orders. The quasi-a priori approach estimates the error while the residual of the time-iterative method is not negligible. Furthermore, the method permits one to decouple the surface and the volume contributions of the truncation error, and provides information about the anisotropy of the solution as well as its rate of convergence in polynomial order. First, we focus on the analysis of one dimensional scalar conservation laws to examine the accuracy of the estimate. Then, we extend the analysis to two dimensional problems. We demonstrate that this quasi-a priori approach yields a spectrally accurate estimate of the truncation error.

Kinematics and Local Motion Planning for Quasi-static Whole-body Mobile Manipulation

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.

Measuring the effectiveness of two public policies on the sectors of labor markets and urban infraestructure. Experimental and quasi-experimental evidence from developing countries

La tesis presenta evidencia rigurosa de la efectividad de las políticas públicas utilizando metodologías experimentales y cuasi-experimentales. La tesis comienza con una introducción completa y una revisión rigurosa de las metodologías que se utilizarán en el análisis posterior de los datos. El primer capítulo, "Habilidades personales y habilidades técnicas en programas de formación de jóvenes. Evidencia Experimental de Largo Plazo de República Dominicana ", evalúa el impacto de un programa de empleo de los jóvenes en una serie de variables de interés. El programa ofrece capacitación en las habilidades vocacionales y en las habilidades no cognitivas a jóvenes en riesgo de exclusión social. Cabe destacar que la metodología utilizada para evaluar el programa es un ensayo controlado aleatorio, que proporciona evidencia robusta del efecto causal del programa. Mientras que estudios previos analizaron el impacto de los programas para jóvenes relacionados, ningún estudio anterior había evaluado los efectos de 4 años después de la implementación del programa. Esto representa una contribución importante debido a que las ganancias a corto plazo de varios programas de desarrollo han demostrado no ser sostenida en el tiempo. Esto es también lo que este estudio encuentra para los resultados del mercado de trabajo: mientras que el programa genera una mejora a corto plazo de los resultados de empleo para las mujeres, este efecto se disipa en el largo plazo. Sin embargo, el programa parece conducir a cambios persistentes en las expectativas del mercado de trabajo de las mujeres: las mujeres que asistieron al entrenamiento de informar una visión más optimista de las perspectivas del mercado de trabajo hasta 4 años después del programa...

Expanding our Constitutional Horizons: A Comprehensive Study of Quasi-Constitutionality in Canada

A number of laws in Canada which uphold rights are referred to as quasi-constitutional by the courts in recognition of their special importance. Quasi-constitutional statutes are enacted through the regular legislative process, although they are being interpreted and applied in a fashion which has become remarkably similar to constitutional law, and are therefore having an important affect over other legislation. Quasi-constitutionality has surprisingly received limited scholarly attention, and very few serious attempts at explaining its significance have been made. This dissertation undertakes a comprehensive study of quasi-constitutionality which considers its theoretical basis, its interpretation and legal significance, as well as its similarities to comparable forms of law in other Commonwealth jurisdictions. Part I examines the theoretical basis of quasi-constitutionality and its relationship to the Constitution. As a statutory and common law form of fundamental law, quasi-constitutionality is shown to signify an association with the Canadian Constitution and the foundational principles that underpin it. Part II proceeds to consider the special rules of interpretation applied to quasi-constitutional legislation, the basis of this interpretative approach, and the connection between the interpretation of similar provisions in quasi-constitutional legislation and the Constitution. As a statutory form of fundamental law, quasi-constitutional legislation is given a broad, liberal and purposive interpretation which significantly expands the rights which they protect. The theoretical basis of this approach is found in both the fundamental nature of the rights upheld by quasi-constitutional legislation as well as legislative intent. Part III explores how quasi-constitutional statutes affect the interpretation of regular legislation and how they are used for the purposes of judicial review. Quasi-constitutional legislation has a significant influence over regular statutes in the interpretative exercise, which in some instances results in conflicting statutes being declared inoperable. The basis of this form of judicial review is demonstrated to be rooted in statutory interpretation, and as such it provides an interesting model of rights protection and judicial review that is not conflated to constitutional and judicial supremacy.

Report on the Status of Findings and Recommendations from the City of Bertram’s Periodic Examination Report dated August 27, 2014 for the period August 1, 2015 through July 31, 2016

Report on the Status of Findings and Recommendations from the City of Bertram’s Periodic Examination Report dated August 27, 2014 for the period August 1, 2015 through July 31, 2016

Report on the Status of Findings and Recommendations from the City of Olin’s Periodic Examination Report dated November 17, 2014 for the period June 1, 2015 through April 30, 2016

Report on the Status of Findings and Recommendations from the City of Olin’s Periodic Examination Report dated November 17, 2014 for the period June 1, 2015 through April 30, 2016

Report on the Status of Findings and Recommendations from the City of Kelley’s Periodic Examination Report dated December 11, 2014 for the period April 1, 2015 through March 31, 2016

Report on the Status of Findings and Recommendations from the City of Kelley’s Periodic Examination Report dated December 11, 2014 for the period April 1, 2015 through March 31, 2016

Report on the Status of Findings and Recommendations from the City of Low Moor’s Periodic Examination Report dated November 13, 2014 for the period November 1, 2015 through July 31, 2016

Report on the Status of Findings and Recommendations from the City of Low Moor’s Periodic Examination Report dated November 13, 2014 for the period November 1, 2015 through July 31, 2016

Report on the Status of Findings and Recommendations on the City of Randalia’s Periodic Examination Report dated March 25, 2015

Report on the Status of Findings and Recommendations on the City of Randalia’s Periodic Examination Report dated March 25, 2015

Report on the Status of Findings and Recommendations from the City of Gilman’s Periodic Examination Report dated October 10, 2014 for the period June 1, 2015 through February 29, 2016

Report on the Status of Findings and Recommendations from the City of Gilman’s Periodic Examination Report dated October 10, 2014 for the period June 1, 2015 through February 29, 2016

Report on the Status of Findings and Recommendations on the City of Kimballton’s Periodic Examination Report dated August 11, 2014 for the period December 1, 2015 through May 31, 2016

Report on the Status of Findings and Recommendations on the City of Kimballton’s Periodic Examination Report dated August 11, 2014 for the period December 1, 2015 through May 31, 2016

Report on the Status of Findings and Recommendations from the City of Harper’s Periodic Examination Report dated December 15, 2014 for the period December 1, 2015 through May 31, 2016

Report on the Status of Findings and Recommendations from the City of Harper’s Periodic Examination Report dated December 15, 2014 for the period December 1, 2015 through May 31, 2016