Multi-parametric numerical simulation of age-specific cancer rates in human populations

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.Includes bibliographical references (p. 138).The CancerFit computer program allows cancer researchers to analyze epidemiologic data describing the age-specific risk of cancer in terms of hypotheses about historical environmental risks, the heritability of cancer, the role of gender and the processes embedded in cancer formation. The program was based on the theories of Professor W. Thilly (MIT), Professor S. Morgenthaler (ETH) and their students. Written as a Fortran program by Prof. Morgenthaler it was transported into Java by David Hensle (MIT) who introduced a number of characteristics that enabled MIT students to perform basic parametric analyses for thesis and coursework in cancer epidemiology. In this thesis, the CancerFit application has been extended to include new functionality that allows computation and subsequent analysis of the ratio of two age-specific cancer incidence or mortality datasets. Originally this ratio was proposed to compare the lifetime risks of children of parents with a specific form of cancer and of parents with at least one child with the same cancer; it does this task as intended. However, its use has permitted me to discover a previously unrecognized excess of colon cancer deaths in women relative to men in the 30-64 year age interval. As this is the same age interval for early breast cancer and ovarian cancer onset in women, this finding points to a more general cancer risk in pre-menopausal women than has been previously recognized. Furthermore, the CancerFit program has been improved by permitting the cancer researcher to include historical age-specific survival rates, overall mortality rates, and reporting error rates when these are available. A user can now input data for each of these rates, which the program uses to adjust the mortality data(cont.) to better approximate the age-specific rate of cancer appearance for the cohort studied. These improvements and new clinical data have permitted a clearer understanding of the age-specific risks and in the case of colorectal cancer appear to permit calculation of the critical parameters in this form of human cancer.by John Kogel.M.Eng

Numerically based proposals for the stiffness and strength of masonry infills with openings in reinforced concrete frames

Aimed at investigating the effect of openings on the in-plane behaviour of masonry infills in reinforced concrete frames, a parametric study is presented based on model calibration via experimental tests. Two types of openings are investigated: central window openings and different combinations of door and window openings based on the typologies of southern European countries. First, a finite element model of the structure is made using the DIANA software program. Then, after calibration with experimental results, a parametric analysis is carried out to investigate the effect of the presence and location of the different types of openings on the in-plane behaviour of the infilled frame. Finally, different equations for predicting the initial stiffness and lateral strength of infilled frames with any types of openings were obtained. An α factor related to the geometry of the piers between openings is proposed to take into account the location of the openings in the developed equations. Subsequently, the masonry infill panel is replaced by a diagonal strut. An empirical equation is also proposed for the width of an equivalent strut to replace a masonry infill panel with openings in such a way that they possess the same initial stiffness.The authors would like to acknowledge the Portuguese Foundation for Science and Technology (FCT) for funding the research project RetroInf – Developing innovative solutions for seismic retrofitting of masonry infill walls (PTDC/ECM/122347/2010)

A vulnerability index formulation for the seismic vulnerability assessment of vernacular architecture

The valorization and preservation of vernacular architecture, as well as traditional construction techniques and materials, is a key-element for cultural identity. Conservation efforts are often mainly focused on historical constructions and monuments. Furthermore, more detailed and sophisticated seismic vulnerability assessment approaches typically used for monumental buildings require time, cost and resources that are not commonly assigned to the study of vernacular architecture. Earthquakes come unexpectedly, endangering in-use vernacular architecture and the population who inhabits it. That is why simplified methods for the seismic vulnerability assessment of vernacular architecture are of paramount importance. The present paper presents a new formulation for the vulnerability index method particularly adapted to the characteristics of vernacular architecture: Seismic Vulnerability Index for Vernacular Architecture (SVIVA). The vulnerability index method has been used extensively in the literature using different formulations that were always defined based on empirical knowledge acquired through post-earthquake damage observation and expert judgment. The SVIVA formulation is developed by means of an analytical process instead of the traditional empirical approach. The process included an extensive numerical modeling campaign that allows adapting the method to the characteristics of vernacular architecture by gaining a deeper quantitative knowledge on their seismic behavior.The work presented in this paper was partly financed by FEDER funds through the Competitivity and Internationalization Operational Programme - COMPETE and by national funds through FCT - Foundation for Science and Technology within the scope of the project POCI-01-01-0145-FEDER-007633

High temperature micromechanical behavior of a Pt-modified nickel aluminide bond-coating and of its interdiffusion zone with the superalloy substrate

The micromechanical properties of a b-(Ni,Pt)Al bondcoating was investigated between 700°C and 1000°C using ultrathin freestanding bond-coating specimens. Its brittle-to-ductile transition temperature was close to 750°C, with a significant ductility above 800°C (up to 23 pct at 1000°C). The tensile strength decreased from 450 MPa at 750°C down to 50 MPa at 1000°C. Fractographic observations evidenced the material brittleness at intermediate temperature with large cleaved grains and its ductility above 750°C with important necking of individual grains

Numerical investigation of liquid film instabilities and evaporation in confined oscillating slug-plug flows

An enhanced volume of fluid (VOF)-based numerical simulation framework that accounts for conjugate heat transfer between solid and two-phase flow regions and phase-change due to boiling/condensation, is utilised in order to investigate the effect of flow oscillation amplitude and frequency on the liquid film evaporation and instability formation in slug-plug flows within heated channels, in saturated flow boiling conditions. Various series of parametric numerical simulations are performed, for different values of flow oscillation amplitude and frequency for a variety of working fluids. For one of the working fluids two different channel diameters are also tested. The oscillations in each case are induced by applying an oscillating pressure boundary condition at the inlet of the channel, keeping the pressure constant at the outlet, after an initial period of constant pressure drop between the inlet and the outlet. Capillary ridges that are initiated at the liquid film, in the vicinity of the leading edge of the considered vapour slugs, are identified as a result of the imposed oscillations, which are translated in the form of capillary waves towards the rear end of the bubbles. It is shown that the formation frequency as well as the geometric characteristics of the generated ridges, are directly related to the corresponding frequency and amplitude of the induced flow oscillations. Furthermore, it is shown that in the initial stages of the bubble fate after the application of the oscillations liquid film evaporation is enhanced with the increase of the oscillation amplitude while it degrades as the frequency of the oscillation becomes higher. However, for large oscillation amplitudes and channel diameters, liquid jets penetrate into the elongated bubbles leading in a lot of cases to bubble break-up

A slotted lotus shaped microstrip antenna based an EBG structure

The objective of this paper is to study intensively the design of a printed slotted patch based lotus shape structure mounted on a dielectric substrate backed with an electromagnetic band Gap (EBG) layer for wideband applications. The dielectric substrate is made of a Roger RT/duroid®5880 layer. An EBG layer is introduced on the back profile of the substrate to provide a high gain bandwidth product over wide frequency bands. The antenna is fed with a novel coplanar waveguide (CPW) structure of a flared geometry; therefore, the ground plane is mounted on the same substrate surface with the patch structure. A conductive trace is introduced at the substrate back from the bottom connected to the CPW through two shoring plates to remove the effects of the EBG layer on the feed structure. The EBG performance and the antenna design methodology are discussed using analytical analyses and numerical parametric studies, respectively. The numerical simulation is conducted using CST MWS Finally; the optimal antenna design is fabricated and measured for validation to be compared to the simulated results

0.52eV Quaternary InGaAsSb Thermophotovoltaic Diode Technology

Thermophotovoltaic (TPV) diodes fabricated from 0.52eV lattice-matched InGaAsSb alloys are grown by Metal Organic Vapor Phase Epitaxy (MOVPE) on GaSb substrates. 4cm{sup 2} multi-chip diode modules with front-surface spectral filters were tested in a vacuum cavity and attained measured efficiency and power density of 19% and 0.58 W/cm{sup 2} respectively at operating at temperatures of T{sub radiator} = 950 C and T{sub diode} = 27 C. Device modeling and minority carrier lifetime measurements of double heterostructure lifetime specimens indicate that diode conversion efficiency is limited predominantly by interface recombination and photon energy loss to the GaSb substrate and back ohmic contact. Recent improvements to the diode include lattice-matched p-type AlGaAsSb passivating layers with interface recombination velocities less than 100 cm/s and new processing techniques enabling thinned substrates and back surface reflectors. Modeling predictions of these improvements to the diode architecture indicate that conversion efficiencies from 27-30% and {approx}0.85 W/cm{sup 2} could be attained under the above operating temperatures