Plant and Laboratory Scale Studies of High Performance Concrete for Bridge Decks in West Virginia

High-performance concrete (HPC) is increasingly used in bridge decks due to its high strength, superior durability and low maintenance resulting in durable and cost effective bridges. FHWA strongly recommended developing suitable HPC mixtures using local material sources and construction technologies for a specific location or state.;As part of a comprehensive R&D program, a field implementation of laboratory developed HPC mixtures was proposed. From a total of eight mixtures developed in the lab with w/cm=0.40, three HPC mixtures were selected using specific local aggregates, in addition to supplementary cementitious materials and chemical admixtures. From these mixtures, three test slabs were produced at a concrete plant in West Virginia, by simulating typical construction practices. The plant-produced slabs were monitored and evaluated for temperature, weather, fresh, hardened, and durability properties for over 90 days from summer to early winter. Maturity-strength relationships were established. Microscopic determination of air-void parameters were conducted using a proposed new method and compared with standard method. Finally, concrete cores were examined by petrography to determine w/cm ratio, compositional variations, and other possible depositions within hardened slabs. The properties of field-mixed match-cured, field-mixed laboratory-cured and laboratory-mixed specimens were compared to check the performance of concrete designed in the laboratory and used in the field.;The results showed that all combinations performed well, with slag + silica fume combinations being the best in terms of compressive strength, resistance to freezing and thawing, and chloride ions penetration. The proposed new method for estimating the air-void parameters was found to be more representative than standard methods. The petrographic examination revealed that aggregates, w/cm ratio, and cementitious materials contents were consistent with the original mixture design. This study will be used to develop guidelines for full-scale demonstration projects for the state of West Virginia

Preparation and decay of a single quantum of vibration at ambient conditions

A single quantum of excitation of a mechanical oscillator is a textbook example of the principles of quantum physics. Mechanical oscillators, despite their pervasive presence in nature and modern technology, do not generically exist in an excited Fock state. In the past few years, careful isolation of GHz-frequency nano-scale oscillators has allowed experimenters to prepare such states at milli-Kelvin temperatures. These developments illustrate the tension between the basic predictions of quantum mechanics that should apply to all mechanical oscillators existing even at ambient conditions, and the complex experiments in extreme conditions required to observe those predictions. We resolve the tension by creating a single Fock state of a vibration mode of a crystal at room temperature using a technique that can be applied to any Raman-active system. After exciting a bulk diamond with a femtosecond laser pulse and detecting a Stokes-shifted photon, the 40~THz Raman-active internal vibrational mode is prepared in the Fock state $|1>$ with $98.5\%$ probability. The vibrational state is read out by a subsequent pulse, which when subjected to a Hanbury-Brown-Twiss intensity correlation measurement reveals the sub-Poisson number statistics of the vibrational mode. By controlling the delay between the two pulses we are able to witness the decay of the vibrational Fock state over its $3.9$ ps lifetime at room temperature. Our technique is agnostic to specific selection rules, and should thus be applicable to any Raman-active medium, opening a new generic approach to the experimental study of quantum effects related to vibrational degrees of freedom in molecules and solid-state systems

Formulación de un plan de negocio para lanzar en el Valle de Aburrá el Tinto de Verano embotellado y enlatado en presentación de 330 ml.

57 páginasEl presente proyecto es un plan de negocios para lanzar en el Valle de Aburrá una nueva bebida alcohólica refrescante llamada tinto de verano, cuyo principal valor agregado es su presentación personal (botella de 330 ml) y un suave sabor en combinación con un alto contenido de alcohol del 7,5% frente al de las cervezas que en promedio es del 4.5%. Este producto está dirigido a un público joven (20 a 35 años) de los estratos socioeconómicos 4, 5 y 6.PregradoIngeniero(a) Administrativo(a

Album de asombros

Colombia mágica. Diego Samper Martínez. Editerial Colina, Medellín, 1993, 222 págs., ilus

Asistencia técnica a la dirección de obra de edificio en altura

Práctica Supervisada (IC)--FCEFN-UNC, 2016Trata de tomar contacto con la realidad local de la industria de la construcción, distinguiendo a los distintos actores intervinientes (inversores, constructora, clientes, proveedores, contratistas, empleados, etc), sus características y funciones e interactuar con ello

Una vida para enseñar y pintar

Rafael Sáenz: profesar la pintura. Luz Análida Aguirre Restrepo. Editorial Universidad de Antioquia, Medellín, 2013, 166 págs., il

Emprendedores éticos e industriosos

Ética, trabajo y productividad en Antioquia. Alberto Mayor Mora. Ediciones Tercer Mundo. Bogotá. 1984, 537 págs., (ilutrado

¿“Fisuras” o asimilaciones?

Fisuras del arte moderno en Colombia. Carmen María Jaramillo. Imprenta Distrital, Bogotá, 2012, 393 págs., il

Essays in Centralized Market Allocaitons

A long-standing policy concern in many countries is the difficulty of filling medical positions in rural areas. In Colombia, the Ministry of Health requires newly graduated health professionals to work in a rural or marginalized urban area for a year in order to receive professional certification. The decentralized mechanism used until 2013 to allocate graduates to slots was one that health professionals could manipulate to avoid an assignment. In 2014, a single-offer centralized mechanism that cannot be manipulated to avoid an assignment, based on Gale and Shapley’s deferred acceptance algorithm, was adopted. Following a revealed preference approach, I estimate health professionals’ hospital preferences using the 2014 data. Using these estimates and the fact that under the decentralized mechanism health professionals were able to avoid positions that fall below their acceptance threshold, I obtain the average marginal utility a health professional would require to accept a position by simulating the outcome had the decentralized mechanism still been in use. Then, I simulate the outcome of the centralized mechanism in the absence of the requirement that students accept the assignment determined by the mechanism. I find that, given the choice, about 30% of physicians would be left unassigned, im plying that it is important for the policy’s success that assignments be mandatory. I review many algorithms that have been discussed in the literature and find some that result in significant welfare gains. Finally, I show that, in this setting, there is no evidence that manipulable mechanisms can yield a higher welfare gains