Dynamics of laser produced silver plasma under film deposition conditions studied using optical emission spectroscopy

Laser produced plasma from silver is generated using a Q-switched Nd:YAG laser. Optical emission spectroscopy is used to carry out time of flight (TOF) analysis of atomic particles. An anomalous double peak profile in the TOF distribution is observed at low pressure. A collection of slower species emerge at reduced pressure below 4 X lO-3 mbar and this species has a greater velocity spread. At high pressure the plasma expansion follows the shockwave model with cylindrical symmetry whereas at reduced pressure it shows unsteady adiabatic expansion (UAE). During UAE the species show a parabolic increases in the expansion time with radial distance whereas during shock wave expansion the exponent is less than one. The angular distribution of the ablated species in the plume is obtained from the measurement of optical density of thin films deposited on to glass substrates kept perpendicular to the plume. There is a sharp variation in the film thickness away from the film centre due to asymmetries in the plume.

Ground-state self-consistent calculation of quantum dots under magnetic fields: Addition spectrum

A density-functional self-consistent calculation of the ground-state electronic density of quantum dots under an arbitrary magnetic field is performed. We consider a parabolic lateral confining potential. The addition energy, E(N+1)-E(N), where N is the number of electrons, is compared with experimental data and the different contributions to the energy are analyzed. The Hamiltonian is modeled by a density functional, which includes the exchange and correlation interactions and the local formation of Landau levels for different equilibrium spin populations. We obtain an analytical expression for the critical density under which spontaneous polarization, induced by the exchange interaction, takes place.

Theory of differential inequalities with appliciations to singular perturbiation problems and method of lines

During recent years, the theory of differential inequalities has been extensively used to discuss singular perturbation problems and method of lines to partial differential equations. The present thesis deals with some differential inequality theorems and their applications to singularly perturbed initial value problems, boundary value problems for ordinary differential equations in Banach space and initial boundary value problems for parabolic differential equations. The method of lines to parabolic and elliptic differential equations are also dealt The thesis is organised into nine chapters

Development of solar air heaters & thermal energy storage system for drying applications in food processing industries

In the present work, the author has designed and developed all types of solar air heaters called porous and nonporous collectors. The developed solar air heaters were subjected to different air mass flow rates in order to standardize the flow per unit area of the collector. Much attention was given to investigate the performance of the solar air heaters fitted with baffles. The output obtained from the experiments on pilot models, helped the installation of solar air heating system for industrial drying applications also. Apart from these, various types of solar dryers, for small and medium scale drying applications, were also built up. The feasibility of ‘latent heat thermal energy storage system’ based on Phase Change Material was also undertaken. The application of solar greenhouse for drying industrial effluent was analyzed in the present study and a solar greenhouse was developed. The effectiveness of Computational Fluid Dynamics (CFD) in the field of solar air heaters was also analyzed. The thesis is divided into eight chapters.

Spin polarized neutron matter and magnetic susceptibility within the Brueckner-Hartree-Fock approximation

The Brueckner-Hartree-Fock formalism is applied to study spin polarized neutron matter properties. Results of the total energy per particle as a function of the spin polarization and density are presented for two modern realistic nucleon-nucleon interactions, Nijmegen II and Reid93. We find that the dependence of the energy on the spin polarization is practically parabolic in the full range of polarizations. The magnetic susceptibility of the system is computed. Our results show no indication of a ferromagnetic transition which becomes even more difficult as the density increases.

Mobility Metric based LEACH-Mobile Protocol

Cluster based protocols like LEACH were found best suited for routing in wireless sensor networks. In mobility centric environments some improvements were suggested in the basic scheme. LEACH-Mobile is one such protocol. The basic LEACH protocol is improved in the mobile scenario by ensuring whether a sensor node is able to communicate with its cluster head. Since all the nodes, including cluster head is moving it will be better to elect a node as cluster head which is having less mobility related to its neighbours. In this paper, LEACH-Mobile protocol has been enhanced based on a mobility metric “remoteness” for cluster head election. This ensures high success rate in data transfer between the cluster head and the collector nodes even though nodes are moving. We have simulated and compared our LEACH-Mobile-Enhanced protocol with LEACHMobile. Results show that inclusion of neighbouring node information improves the routing protocol.

Mobility Metric based LEACH-Mobile Protocol

Cluster based protocols like LEACH were found best suited for routing in wireless sensor networks. In mobility centric environments some improvements were suggested in the basic scheme. LEACH-Mobile is one such protocol. The basic LEACH protocol is improved in the mobile scenario by ensuring whether a sensor node is able to communicate with its cluster head. Since all the nodes, including cluster head is moving it will be better to elect a node as cluster head which is having less mobility related to its neighbours. In this paper, LEACH-Mobile protocol has been enhanced based on a mobility metric “remoteness” for cluster head election. This ensures high success rate in data transfer between the cluster head and the collector nodes even though nodes are moving. We have simulated and compared our LEACH-Mobile-Enhanced protocol with LEACHMobile. Results show that inclusion of neighbouring node information improves the routing protocol.

Short-Term Load Forecast Of A Low Loadfactor Power System For Optimization Of Merit Order Dispatch Using Adaptive Learning Algorithm

Short term load forecasting is one of the key inputs to optimize the management of power system. Almost 60-65% of revenue expenditure of a distribution company is against power purchase. Cost of power depends on source of power. Hence any optimization strategy involves optimization in scheduling power from various sources. As the scheduling involves many technical and commercial considerations and constraints, the efficiency in scheduling depends on the accuracy of load forecast. Load forecasting is a topic much visited in research world and a number of papers using different techniques are already presented. The accuracy of forecast for the purpose of merit order dispatch decisions depends on the extent of the permissible variation in generation limits. For a system with low load factor, the peak and the off peak trough are prominent and the forecast should be able to identify these points to more accuracy rather than minimizing the error in the energy content. In this paper an attempt is made to apply Artificial Neural Network (ANN) with supervised learning based approach to make short term load forecasting for a power system with comparatively low load factor. Such power systems are usual in tropical areas with concentrated rainy season for a considerable period of the year

Numerical Simulation of Electroosmotic Flow with Step Change in Zeta Potential

Electroosmotic flow is a convenient mechanism for transporting polar fluid in a microfluidic device. The flow is generated through the application of an external electric field that acts on the free charges that exists in a thin Debye layer at the channel walls. The charge on the wall is due to the chemistry of the solid-fluid interface, and it can vary along the channel, e.g. due to modification of the wall. This investigation focuses on the simulation of the electroosmotic flow (EOF) profile in a cylindrical microchannel with step change in zeta potential. The modified Navier-Stoke equation governing the velocity field and a non-linear two-dimensional Poisson-Boltzmann equation governing the electrical double-layer (EDL) field distribution are solved numerically using finite control-volume method. Continuities of flow rate and electric current are enforced resulting in a non-uniform electrical field and pressure gradient distribution along the channel. The resulting parabolic velocity distribution at the junction of the step change in zeta potential, which is more typical of a pressure-driven velocity flow profile, is obtained.

Experience in introduction of English terminology in engineering lessons: methodology and evaluation

This communication explains a experience for the introduction of English terminology in a technical degree of higher education. We present the methodology and assessment procedures used to evaluate the way the students perceived the introduction of terminology in English in two different subjects from 3rd and 5th year courses of a Computer Science degree in which English was not the vehicular language. We propose a strategy based on two main pillars, namely: 1) The design of materials, explanations, and exams, paying particular attention to the way in which the specific terminology was exposed to the students, and 2) The assessment of the impact in the students by means of the analysis of the feedback trough a set of enquiries. Our experience showed that the students responded very positively to the introduction of English terminology, and presented an affirmative feedback about the impact that an improvement of their linguistic abilities would have in their future work. Further, we present statistics regarding the use of English as the vehicular language for technical reports, which is envisaged as very useful by the students. Finally, we propose a set of questions for further debate which are centered in the role that English terminology should pay in technical degrees, and about the way in which universities should deploy resources in English languages within the different Syllabus

El Lloc dels riscos naturals als Annales de Géographie (1891-1991)

L'étude des risques naturels est devenu un sujet de débat entre les géographes physiques français, de plus en plus conscients de l'exposition croissante des sociétés aux risques naturels et du besoin d'évaluer leurs compétences et leurs moyens d'intervention. Mais l'étude des risques naturels a aussi été un sujet récurrent dans l'histoire de la géographie française. Cet article prétend être une approche au traitement qu'a reçu ce thème dans les Annales de Géographie depuis sa création jusqu'h aujourd’hui. Après avoir distingué trois étapes (1891-1930, 1930-1975 et 1975-1991) on a établi les rapports existants entre les différents moments de la géographie française et l'étude des risques naturels et on a analysé autant le contenu des notices sur les divers évènements catastrophiques que les travaux des auteurs les plus représentatifs. I1 s'agit, en résumé, de proposer une réflexion sur la façon dont la géographie française a abordé ce sujet

CORPOICA en los procesos de reestructuración económica del sector agroindustrial colombiano en los noventa

La Corporación Colombiana de Investigación Agropecuaria, CORPOICA, es una organización que involucra a diversos actores distintos del Estado. CORPOICA surgió cuando Colombia experimentaba un cambio en la estructura del sistema nacional de investigación agrícola, junto con los procesos de modernización del Estado y la apertura económica. Esta investigación se centra en la política pública de Ciencia y Tecnología que dio origen a CORPOICA, para determinar los factores que impulsaron la alianza entre el sector público y privado que caracterizó el sistema nacional de investigación agrícola, implementado en la última década del siglo XX.

Madres de corazón

“Madres de Corazón” es una crónica periodística que relata la historia de una madre sustituta perteneciente a la ONG "Aldeas Infantiles SOS". La historia describe la forma como esta mujer les brinda un hogar a ocho niños y niñas que han perdido el cuidado de sus padres biológicos. A través de la crónica se aborda el tema del abandono infantil, el funcionamiento de la organización y la manera como un ambiente de familia se convierte en algo esencial para el desarrollo integral de estos niños.

El Forment a la Barcelona baixmedieval: preus, mesures i fiscalitat (1283-1345)

A través de l'anàlisi de dos sèries de diferents llibres de comptabilitat de Barcelona, els procedents de la gestió dels molins reals i els redactats per una institució eclesiàstica, la Pia Almoina, vam començar a estudiar el mercat del blat a Barcelona durant l'edat mitjana. Hem analitzat anteriorment el valor de les mesures a Barcelona i, per poder qualificar el preu real del pa, també hem estudiat els diferents processos industrials per fer pa de blat. Després, hem analitzat el conjunt d'impostos que pesaven sobre la comercialització de cereals. A través de l'estudi de l'evolució dels preus, hem tractat de fer una primera aproximació de la primera etapa de la crisi baixmedieval, concretament entre 1283 i 1345, tenint en compte els contrastos amb els treballs ja coneguts sobre la base de les fonts on la noció de quantitat no va ser considerada. Finalment, hem comparat els nostres resultats amb alguns treballs referents a la Corona d'Aragó i el món mediterrani, a fi d'obtenir una idea més precisa de la cronologia de les crisis de subsistència

Prevalencia y factores asociados de síntomas osteomusculares en miembro superior y cuello en los trabajadores de un call center

Objetivo: determinar la prevalencia en los últimos 6 meses de los síntomas de cuello y miembro superior además de sus factores asociados, en trabajadores de una entidad financiera call center en el periodo comprendido de abril a octubre del año 2009. Métodos: se realizó un análisis descriptivo trasversal, a través de la aplicación de un cuestionario de morbilidad sentida que abarcó aspectos demográficos, antecedentes personales y antecedentes laborales. La presencia de los síntomas se documentó en una tabla donde se confrontaron los síntomas osteomusculares y los segmentos afectados en los últimos 6 meses. Adicionalmente se les pidió a los sujetos identificar la postura más frecuente durante su trabajo mediante un diagrama. Resultados: los síntomas más prevalentes fueron dolor en la muñeca derecha (0,44; IC 95% 0,37 – 0,51), dolor en el cuello (0,43; IC95% 0,36 – 0,50), rigidez en el cuello (0,33; IC95% 0,26 – 0,40) y dolor en la mano derecha (0,36; IC95% 0,29 – 0,43). Se encontraron diferencias estadísticamente significativas en cuanto al género en la presencia de dolor en muñeca derecha (26,1% hombres contra 73,9% mujeres; p=0,005), dolor en mano derecha (25% hombres versus 75% mujeres; p=0,008), síntomas neurológicos en mano derecha (19,4% versus 80,6%; p=0,001) y dolor en hombro derecho (26,3% hombres versus 73,7% mujeres; p=0,048). También se evidencio una diferencia estadísticamente significativa en la prevalencia del síntoma dolor en muñeca derecha según el auto reporte de mayor exigencia en el desempeño (85,2% con la percepción de mayor exigencias, versus 14,8% en los sujetos que no; p=0,020). Además una diferencia estadísticamente significativa con mayor presencia de síntomas en muñecas y manos en sujetos con postura en dorsiflexión de de las mismas (muñeca derecha 72,8%, p=0,001; muñeca izquierda 43,5%, p=0,020; mano derecha 62%, p=0,003). Conclusión: después de realizar el estudio se encontró como principal síntoma el dolor, localizado en: la muñeca derecha, el cuello, la mano derecha y el hombro derecho, con diferencias mayores para el género femenino según la postura de las muñecas, lo que es compatible con las condiciones de trabajo y la respuesta fisiológica a estas condiciones.