Optimización y síntesis de redes de agua asociadas a plantas de proceso

Bajo hipótesis razonables de ausencia de corrientes de reciclo y recirculaciones en el método de síntesis se propone la partición del espacio de búsqueda de diseño, que implica la descomposición de una superestructura compleja en un conjunto de superestructuras básicas de red. El mejor diseño en cada superestructura básica de red es determinado resolviendo un conjunto de problemas de programación lineal (PL), expresados a partir de la reformulación de un modelo matemático no convexo estructurado. La exploración sistemática del espacio paramétrico definido por las variables fraccionales del problema, produce del espacio solución contenido por las superestructuras básicas de red, un diseño alternativo óptimo global de red. Se propone una estrategia de solución robusta, en dos fases, donde es posible controlar la complejidad que exhiben los modelos matemáticos por la presencia de los términos bilineales, sobre las regiones del espacio de búsqueda de diseño. A diferencia de otras metodologías de diseño de sistemas de tratamiento de efluentes basados en estrategias de descomposición de modelos matemáticos que pueden presentar problemas durante la solución, principalmente por la suposición de buenos puntos de arranque y que pueden exhibir soluciones subóptimas. En esta disertación, el método propuesto supera estas desventajas al conducir un procedimiento heurístico-paramétrico de optimización global, con alternativas atractivas de proyecto y útiles para la toma de decisiones durante el diseño. El método se ha probado para el diseño de sistemas de tratamiento de efluentes para un número de ejemplos de la literatura, obteniéndose mejores resultados, en particular para ejemplos complicados.El objetivo de esta disertación consistió en investigar el problema de optimización y síntesis de sistemas distribuidos de tratamiento de efluentes. La motivación surge del hecho que a pesar de que los procesos de tratamiento de efluentes se utilizan ampliamente en la industria, la estructura y sus propiedades no se han estudiado de manera metodológica para producir un diseño eficiente y robusto. En esta disertación se desarrolla una metodología sistemática para la optimización y síntesis de sistemas distribuidos de tratamiento de efluentes. El desarrollo de procedimientos sistemáticos de síntesis de tales sistemas permite diseñar la estructura y el cálculo de sus propiedades al menor costo total, e investigar sobre la robustez del diseño para explorar la posibilidad de mejorar su construcción y funcionamiento por conceptos de análisis de sensibilidad en las variables de diseño. La naturaleza no convexa de los modelos matemáticos que describen este tipo de problemas, y la capacidad de manejar múltiples contaminantes, corrientes y unidades de tratamiento, introducen en el sistema complejidades y un crecimiento exponencial del número de posibilidades de configuraciones topológicas. Estas son algunas de las dificultades que han derivado en investigaciones con diferentes metodologías, principalmente conceptuales del tipo punto de pliegue, y de programación matemática. El método propuesto se ha desarrollado con base en conceptos de partición del espacio de búsqueda de diseño no convexo, formulación de modelos matemáticos estructurados del proceso de tratamiento de programación no lineal (PNL) y programación lineal (PL) en estado estacionario, y propuestas de estrategias de solución

A multifunctional sensor system for brake system applications

The objective of this thesis is to develop a multifunctional MEMS (Micro Electro Mechanical System) sensor system for the simultaneous measurement of pressure and temperature inside a hydraulic system, more specifically a hydraulic brake system for automotive applications. The multifunctional pressure and temperature sensor system presented in this Thesis was designed to be installed in a new brake-by-wire system that requires the simultaneous reading of pressure and temperature per wheel cylinder. This system needs to control and monitor these parameters at each wheel cylinder to adjust the pressure for optimal braking. Current sensing systems installed in regular brake systems use a single pressure sensor that is positioned in the main cylinder and they do not include a temperature sensor. Moreover, while numerous approaches have been taken to control and monitor the pressure in a brake system real-time, no MEMS sensor system has yet been reported that can carry out real-time measurements of the brake system's pressure and temperature. In a representative automobile hydraulic brake system, the pressure and temperature can reach up to about 4 Mpa and 120 °C, respectively. These conditions are developed in an oily environment with a pH ~ 11. The multifunctional sensor system presented here is based on the two sensors, one for pressure and one for temperature, working within the same packaging. These two sensors are glued on the surface of an adequate Transistor Outline (TO) base using a temperature resistance adhesive. The substrate with the two sensors is covered by a parylene layer for dielectric protection, protection from the corrosive medium and protection from the moisture inherent in the brake fluid. The interface of the sensor system to the hydraulic brake system uses a commercial 1/4 18 NPT fitting customized to serve as an interface as well as a metal shell between the sensor and the hydraulic cylinder. The TO base and the metal shell were joined by micro-brazing to minimize heat-affected areas and ensure that critical components are unharmed. A finite element model to understand the effect of the parylene layer on the performance of the sensors was developed using COMSOL Multiphysics®. The model was validated by testing many prototypes of the developed sensor system using a custom made hydraulic hand pump which pressure is monitored by a digital hydraulic pressure gauge. The sample fitting is covered by a coil heater that includes a type -T Thermocouple positioned close to the sample to monitor the temperature. The complete apparatus allowed characterization of the test sensor from room pressure (13 psi) to 500 psi over a temperature range of 25 to 120°C. The test samples were characterized from atmospheric pressure to 450 psi over a temperature range of 25 to 120°C. The experimental data shows a reduction in pressure sensitivity of 18.2 % due to the parylene layer which closely agrees with the model predictions of a reduction of 21%. In summary, a multifunctional sensor system has been developed that can be used to control and monitor the pressure and temperature of a hydraulic cylinder real-time. The sensor system is novel in that it measures both parameters at a single point real-time with good sensitivity and accuracy making it ideal for applications in brake-by-wire systems

Validation of the Orthogonal Tilt Reconstruction Method with a Biological Test Sample

Electron microscopy of frozen-hydrated samples (cryo-EM) can yield high resolution structures of macromolecular complexes by accurately determining the orientation of large numbers of experimental views of the sample relative to an existing 3D model. The “initial model problem”, the challenge of obtaining these orientations ab initio, remains a major bottleneck in determining the structure of novel macromolecules, chiefly those lacking internal symmetry. We previously proposed a method for the generation of initial models – orthogonal tilt reconstruction (OTR) – that bypasses limitations inherent to the other two existing methods, random conical tilt (RCT) and angular reconstitution (AR). Here we present a validation of OTR with a biological test sample whose structure was previously solved by RCT: the complex between the yeast exosome and the subunit Rrp44. We show that, as originally demonstrated with synthetic data, OTR generates initial models that do not exhibit the “missing cone” artifacts associated with RCT and show an isotropic distribution of information when compared with the known structure. This eliminates the need for further user intervention to solve these artifacts and makes OTR ideal for automation and the analysis of heterogeneous samples. With the former in mind, we propose a set of simple quantitative criteria that can be used, in combination, to select from a large set of initial reconstructions a subset that can be used as reliable references for refinement to higher resolution.Molecular and Cellular Biolog

Down-regulation of transforming growth factor-β type II receptor (TGF-βRII) protein and mRNA expression in cervical cancer

<p>Abstract</p> <p>Background</p> <p>Cervical carcinogenesis is a multistep process initiated by "high risk" human papillomaviruses (HR-HPV), most commonly HPV16. The infection <it>per se </it>is, however, not sufficient to induce malignant conversion. Transforming Growth Factor β (TGF-β) inhibits epithelial proliferation and altered expression of TGF-β or its receptors may be important in carcinogenesis. One cofactor candidate to initiate neoplasia in cervical cancer is the prolonged exposure to sex hormones. Interestingly, previous studies demonstrated that estrogens suppress TGF-β induced gene expression. To examine the expression of TGF-β2, TGF-βRII, p15 and c-myc we used <it>in situ </it>RT-PCR, real-time PCR and immunohistochemistry in transgenic mice expressing the oncogene E7 of HPV16 under control of the human Keratin-14 promoter (K14-E7 transgenic mice) and nontransgenic control mice treated for 6 months with slow release pellets of 17β-estradiol.</p> <p>Results</p> <p>Estrogen-induced carcinogenesis was accompanied by an increase in the incidence and distribution of proliferating cells solely within the cervical and vaginal squamous epithelium of K14-E7 mice. TGF-β2 mRNA and protein levels increased in K14-E7 transgenic mice as compared with nontransgenic mice and further increased after hormone-treatment in both nontransgenic and transgenic mice. In contrast, TGF-βRII mRNA and protein levels were decreased in K14-E7 transgenic mice compared to nontransgenic mice and these levels were further decreased after hormone treatment in transgenic mice. We also observed that c-myc mRNA levels were high in K14-E7 mice irrespective of estrogen treatment and were increased in estrogen-treated nontransgenic mice. Finally we found that p15 mRNA levels were not increased in K14-E7 mice.</p> <p>Conclusion</p> <p>These results suggest that the synergy between estrogen and E7 in inducing cervical cancer may in part reflect the ability of both factors to modulate TGF-β signal transduction.</p

Modelo proceso-respuesta de recesión de acantilados por variación del nivel del mar. Aplicación en la Costa de Holderness (Reino Unido).

El desarrollo de modelos predictivos de retroceso de acantilados costeros se encuentra limitado desde el punto de vista geomorfológico debido a la complejidad e interacción de los procesos de desarrollo espacio-temporal que tienen lugar en la zona costera. Los códigos de cálculo existentes en la actualidad incorporan modelos probabilísticos para resolver la estabilidad geomecánica de los materiales. Éstos pueden reproducir tasas de recesión históricas; sin embargo, el comportamiento bajo condiciones variables (cambio climático) no tiene por qué ser el mismo. Se presenta un modelo de proceso-respuesta de retroceso de acantilados costeros que incorpora el comportamiento geomecánico de costas compuestas por tills, incluye la acción protectora de los derrubios presentes al pie del acantilado frente a los procesos erosivos y permite evaluar el efecto del ascenso del nivel medio del mar asociado al cambio climático. Para ello, se acoplan la dinámica marina: nivel medio del mar, mareas y oleaje; con la evolución del terreno: erosión, desprendimiento rocoso y formación de talud de derrubios. La erosión del acantilado se calcula en función del nivel del mar, de las condiciones del oleaje incidente, de la pendiente de la plataforma rocosa y de la resistencia del material rocoso afectado en cada ciclo de marea. Al finalizar cada ciclo, se evalúa la ruptura del acantilado según un criterio geomecánico de roturas por vuelco y en caso de rotura, se genera un talud de derrubios al pie del mismo. El modelo ha sido validado frente a datos reales en la costa de Holderness, Yorkshire, Reino Unido. Los resultados obtenidos presentan un importante avance en los modelos de recesión costera, especialmente en su relación con las condiciones geomecánicas del medio y su respuesta ante condiciones variables del nivel medio del mar producidas por el cambio climático

Experimental validation for chatter stability prediction

This research focused on the experimental validation for chatter stability prediction. An optimum machining was aimed to maximize the material removal rate, whilst maintaining a sufficient stability margin to assure the surface quality. High material removal rate in machining produced self-excited vibration or chatter of the cutting tool and the workpiece. This resulted in a poor surface finish and dimensional accuracy, chipping of the cutter teeth, and also may damage the workpiece as well as machining tool. Frequency response function of a single degree freedom flexural was measured and the cutting stiffness of tools were determined in order to be used in predicting chatter stability using semi discretization method. The aluminium 7075 specimens were used in the milling cutting experiment to validate the chatter stability diagram of mill uniform and variable cutters, where a set of spindle speed and depth of cut had tested. The vibration conditions of machining were identified by analysing the vibration signals and FFT spectrum whether it was stable or in a chatter condition. There are good agreement between predicted stability and cutting experiment for the down-milling operation using uniform 4 flute cutting tool. Stable conditions were shown outside the boundary of chatter region. The optimized cutting tool was predicted to suppress chatter. Machining experiment tests showed there were no chatter vibration conditions during machining process until 1.5 mm depth of cut. According to the results of machining experiment, it was proven that the variable tool had more capability to machining without producing chatter vibration as compared to the regular tool