318 research outputs found
Epidemiology of multiple chronic conditions: an international perspective
No full textThe epidemiology of multimorbidity, or multiple chronic conditions (MCCs), is one of the research priority areas of the U.S. Department of Health and Human Services (HHS) by its Strategic Framework on MCCs. A conceptual model addressing methodological issues leading to a valid measurement of the prevalence rates of MCCs has been developed and applied in descriptive epidemiological studies. Comparing these results with those from prevalence studies performed earlier and in other countries is hampered by methodological limitations. Therefore, this paper aims to put the size and patterns of MCCs in the USA, as established within the HHS Strategic Framework on MCCs, in perspective of the findings on the prevalence of MCCs in other countries. General common trends can be observed: increasing prevalence rates with increasing age, and multimorbidity being the rule rather than the exception at old age. Most frequent combinations of chronic diseases include the most frequently occurring single chronic diseases. New descriptive epidemiological studies will probably not provide new results; therefore, future descriptive studies should focus on the prevalence rates of MCCs in subpopulations, statistical clustering of chronic conditions, and the development of the prevalence rates of MCCs over time. The finding of common trends also indicates the necessary transition to a next phase of MCC research, addressing the quality of care of patients with MCCs from an organizational perspective and with respect to the content of care.Journal of Comorbidity 2013;3(2)36–4
AC Loss Modeling of Superconducting Field Windings for a 10MW Wind Turbine Generator - an Analytical and Numerical Analysis
No full textThe total installed capacity of wind turbines is growing as society moves towards a more sustainable energy supply. With the integration of more wind turbines in the grid the price and reliability of future wind turbines are very important. One of the promising drive train topologies currently investigated is the direct drive superconducting wind turbine. This configuration allows for higher reliability, less top mass and nearly full independence of the volatile market of rare earth metals. However, the superconducting windings in such a generator operate only at cryogenic temperatures which is a challenge in the design of the machine. Since superconducting windings operate at a very low temperature it is important to estimate the heat generation in the windings. AC loss is the main cause of heat generation in a superconducting field winding. This thesis attempts to analyse the AC loss in two 10MW superconducting generator designs using analytical and numerical modeling. After introducing the problem description, the theory concerning AC loss in superconducting wires is treated. Then, the methods for both modeling techniques are established and partly validated. The results are then shown and discussed after which the conclusions are drawn. Both generators are designed for the same turbine and therefore have the same rotational speed and rated power which makes them comparable. The geometry however is different and as the results will show, these differences in design result in major differences in AC loss. Depending on machine geometry the analytically calculated AC loss is ranging from 22.2W to 283W in the Non Magnetic Teeth (NMT) design and 0.7kW to 2.9kW in the Iron Teeth (IT) design. The numerically calculated hysteresis loss is on average 154W in the NMT machine and 371W in the IT machine.Sustainable Energy TechnologyElectrical Power EngineeringElectrical Engineering, Mathematics and Computer Scienc
Aluminum nitride for heatspreading in RF IC’s
No full textTo reduce the electrothermal instabilities in silicon-on-glass high-frequency bipolar devices, the integration of thin-film aluminum nitride as a heatspreader is studied. The AlN is deposited by reactive sputtering and this material is shown to fulfill all the requirements for actively draining heat from RF IC’s, i.e., it has good process compatibility, sufficiently high thermal conductivity and good electrical isolation also at high frequencies. The residual stress and the piezoelectric character of the material, both of which can be detrimental for the present application, are minimized by a suitable choice of deposition conditions including variable biasing of the substrate in a multistep deposition cycle. Films of AlN as thick as 4 lm are successfully integrated in RF silicon-on-glass bipolar junction transistors that display a reduction of more than 70% in the value of the thermal resistance
Water Enhancement on CO2 adsorption: Equilibrium studies on an amine sorbent for Direct Air Capture
No full textThis work aims to establish a relationship between CO2 adsorption capacity and water, in the
context of CO2 removal directly from atmosphere (DAC). For this, experimental data was ob-
tained for a broad range of humidity, temperatures and concentrations of CO2 , using a sup-
ported amine sorbent. Subsequently, the CO2 adsorption results were fitted to equilibrium
models from literature and compared with experimental trends. The Stampi-Bombelli and
WADST models revealed the best fittings, being both values of SSR and R2 relatively close
(SSR=0.338, R 2 =0.969 and SSR=0.360, R2 =0.968, respectively).
The measurements were performed through the breakthrough method, on a pilot scale
setup. These were featured with previous experimental work from SPT group for the same
subject. After comparing both data sets, it was observed that the adsorbent had suffered ~20%
degradation. Consequently, a correction factor was applied into previous values.
Experimental results displayed some inconsistencies, which were attributed to the un-
certainty of the correction factor and the complexity of co-adsorption mechanisms. The maxi-
mum observed amount of CO2 adsorbed/kg of adsorbent was 2.25 kg.mol-1 (PCO2 =1000 Pa, T=
5ºC, RH= 84.97%), and ~2.7 mol.kg-1 after the correction factor, which is significantly close to
values found in literature. The CO2 capacity under the presence of water in comparison with
dry conditions (q/qdry ) was also considered to account its enhancement. At PCO2 = 40 Pa, the
capacity adsorption nearly doubled in presence of high moisture content, while at the higher
partial pressures (PCO2 =1000 Pa), humidity seemed to have a reduced impact.
For DAC conditions, experimental trends were well characterized, which follows litera-
ture remarks. Overall, the WADST and Stampi-Bombelli model represented the closest fits. In
addition, an empirical model was proposed based on the observation of experimental trends.
The model is described by a linear function, in which both values of slope and y-intercept were
obtained through logarithmic equations.A tese visa estabelecer uma relação entre a capacidade de adsorção de CO2 e água, no contexto
de captura de CO2 diretamente da atmosfera. Para tal, dados experimentais foram adquiridos
dentro de um intervalo amplo de temperaturas, concentrações de CO2 e água, usando um ad-
sorvente de aminas. De seguida, os dados foram ajustados a modelos mecanísticos da litera-
tura e comparados. Os modelos Stampi-Bombelli e WADST foram os que melhor descreveram
tendências experimentais, apresentando ajustes próximos (SSR=0.338, R2 =0.969 e SSR=0.360,
R2 =0.968, respetivamente).
As medições foram realizadas através do método breakthrough, numa instalação piloto
de laboratório. Os valores foram complementados um trabalho experimental previamente re-
alizados no grupo SPT para o mesmo tópico. Após comparar os dados, observou-se que o
adsorvente sofreu uma degradação de ~20%. Consequentemente, foi aplicado um fator corre-
tivo a valores anteriores.
Os resultados experimentais mostraram algumas inconsistências, que por sua vez foram
atribuídas à incerteza do fator de degradação e à complexidade dos mecanismos de co-adsor-
ção. A quantidade máxima registada de CO2 adsorvido/kg de adsorvente foi de 2.25 kg.mol-1
(PCO2 =1000 Pa, T=5ºC, RH=84.97%), e ~2.7 mol.kg-1 após a fator corretivo, que é significativa-
mente próximo da literatura. A quantidade de CO2 adsorvido em condições húmidas em rela-
ção à de condições secas (q/qdry ) também foi considerada para quantificar o seu acréscimo.
Nas condições de PCO2 = 40 Pa, a capacidade de adsorção quase duplicou na presença de um
alto teor de água, enquanto que a níveis superiores de pressão parcial (PCO2 =1000 Pa), foi ob-
servado um impacto reduzido na capacidade.
Para condições DAC, as tendências foram bem caracterizadas, paralelamente a observa-
ções da literatura. O modelo WADST e Stampi-Bombelli foram os que mais se aproximaram
dos valores deste trabalho. Foi também proposto um modelo empírico com base em tendências
experimentais. O modelo é descrito por uma função linear, cujos valores de declive e ordenada
foram obtidos a partir de equações logarítmicas
Saddle add-on metallization for RF-IC technology
No full textElectrical Engineering, Mathematics and Computer Scienc
Material-Inversion Solid-Phase Epitaxy of p+ Si forElevated Junctions
No full textMicroelectronicsElectrical Engineering, Mathematics and Computer Scienc
Enhancement of AlN Slender Piezoelectric Cantilevers Actuation by PECVD Silicon Nitride Coating
No full textActuation enhancement for AlN piezoelectric cantilevers is achieved by coating slender AlN beams with a thin PECVD silicon nitride (SiN) layer. Very good linearity and high deflection, up to 19 nm/V of actuation deflection for 200 ?m long cantilevers, at quasi-static mode, is obtained for a 500 nm SiN top layer. This value is three times larger than our previously reported value for cantilevers without the SiN layer. The achieved results make these cantilevers, fabricated in a CMOS compatible process, very promising micro/nano actuators.Delft Institute of Microsystems and NanoelectronicsElectrical Engineering, Mathematics and Computer Scienc
Homogeneous superconducting phase in TiN film: A complex impedance study
No full textThe low frequency complex impedance of a high resistivity 92?????cm and 100?nm thick TiN superconducting film has been measured via the transmission of several high sensitivity GHz microresonators, down to TC/50. The temperature dependence of the kinetic inductance follows closely BCS local electrodynamics, with one well defined superconducting gap. This evidences the recovery of a homogeneous superconducting phase in TiN far from the disorder and composition driven transitions. Additionally, we observe a linearity between resonator quality factor and frequency temperature changes, which can be described by a two fluid model.Delft Institute of Microsystems and NanoelectronicsElectrical Engineering, Mathematics and Computer Scienc
High-resistivity nanogranular Co–Al–O films for high-frequency applications
No full textThis work presents a series of high-resistivity nanogranular Co–Al–O films with maximum resistivity of ? 110?m??cm. The films were deposited using pulsed dc reactive sputtering of a Co72Al28 target in an oxygen/argon ambient. The samples were characterized by scanning electron microscopy (SEM), M-H loop measurements, and s-parameter measurements on microstrip transmission lines with Co–Al–O magnetic cores. The high-frequency magnetic permeability profile was extracted from the microstrip measurements. Reduction of deposition power resulted in resistivity enhancement, as well as reduction of coercivity and permeability. SEM images reveal an average grain size of ? 80?nm for films with the highest resistivity.DIMESElectrical Engineering, Mathematics and Computer Scienc
Opinions of professionals about integrating midwife- and obstetrician-led care in The Netherlands
No full textContains fulltext :
171090.pdf (Publisher’s version ) (Open Access)OBJECTIVE: the current division between midwife-led and obstetrician-led care creates fragmentation in maternity care in the Netherlands. This study aims to gain insight into the level of consensus among maternity care professionals about facilitators and barriers related to integration of midwife-led and obstetrician-led care. Integration could result in more personal continuity of care for women who are referred during labour. This may lead to better birth experiences, fewer interventions and better outcomes for both mother and infant. DESIGN: a descriptive study using a questionnaire survey of 300 primary care midwives, 100 clinical midwives and 942 obstetricians. SETTING: the Netherlands in 2013. PARTICIPANTS: 131 (response 44%) primary care midwives, 51 (response 51%) clinical midwives and 242 (response 25%) obstetricians completed the questionnaire. FINDINGS: there was consensus about the clinical midwife caring for labouring women at moderate risk of complications. Although primary care midwives themselves were willing to expand their tasks there was no consensus among respondents on the tasks and responsibilities of the primary care midwife. Professionals agreed on the importance of good collaboration between professionals who should work together as a team. Respondents also agreed that there are conflicting interests related to the payment structure, which are a potential barrier for integrating maternity care. KEY CONCLUSIONS: this study shows that professionals are positive regarding an integrated maternity care system but primary care midwives, clinical midwives and obstetricians have different opinions about the specifications and implementation of this system. IMPLICATION FOR PRACTICE: our findings are in accordance with earlier research, showing that it is too early to design a blueprint for an integrated maternity care model in the Netherlands. To bring about change in the maternity care system, an implementation strategy should be chosen that accounts for differences in interests and opinions between professionals
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