Integrated Thermal Energy Storage System For Air-conditioners With Phase-Change Composites

Thermal energy storage (TES) is a promising solution to store and dispatch energy and shave peak electric load, reducing the operational cost of HVAC systems. We present results of a TES system using phase-change materials (PCM) integrated with an air conditioner. The proposed system uses an organic PCM (tetradecane) encapsulated within compressed expanded natural graphite foams referred to as phase-change composite. The graphite foam encapsulates the PCM eliminating the need for expensive storage vessels, reduces installation costs, and provides higher thermal conductivity that can lead to faster charge/discharge rates. Two serpentines, multi-pass circuits, operating as a heat source and a sink, exchange heat to and from the phase-change composite. These two circuits are embedded in multiple slabs of this material. The “charge” circuit contains the refrigerant that is directly coupled to a vapor compression system, and the “discharge” circuit removes heat from an airstream and releases it into the PCM composite through a water-glycol liquid coupling. This configuration allows for multiple modes of operation depending on the state of charge of the thermal energy storage module, the building air-conditioning load, and the current electricity and demand charges. This flexible operation allows variable air volume capacity control without the need to have a variable capacity refrigeration system. We developed a 21 kW-hr (6 RT-hr) prototype TES system coupled with a commercial air-conditioner to characterize the component-and system-level performance

The dynamics of geometrically compliant mooring systems

Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution June 2000.Geometrically compliant mooring systems that change their shape to accommodate deformations are common in oceanographic and offshore energy production applications. Because of the inherent geometric nonlinearities, analyses of such systems typically require the use of a sophisticated numerical model. This thesis describes one such model and uses that model along with experimental results to develop simpler forms for understanding the dynamic response of geometrically compliant moorings. The numerical program combines the box method spatial discretization with the generalized- a method for temporal integration. Compared to other schemes commonly employed for the temporal integration of the cable dynamics equations, including box method, trapezoidal rule, backward differences, and Newmark’s method, the generalized-a algorithm has the advantages of second-order accuracy, controllable numerical dissipation, and improved stability when applied to the nonlinear problem. The numerical program is validated using results from laboratory and field experiments. Field experiment and numerical results are used to develop a simple model for dynamic tension response to vertical motion in geometrically compliant moorings. As part of that development, the role of inertia, drag, and stiffness in the tension response are explored. For most moorings, the response is dominated by inertial and drag effects. The simple model uses just two terms to accurately capture these effects, including the coupling between inertia and drag. The separability of the responses to vertical and horizontal motions is demonstrated and a preliminary model for the response to horizontal motions is presented. The interaction of the mooring line with the sea floor in catenary moorings is considered. Using video and tension data from laboratory experiments, the tension shock condition at the touchdown point and its implications are observed for the first time. The lateral motion of line along the bottom associated with a shock during unloading may be a significant cause of chain wear in the touchdown region. Results from the laboratory experiments are also used to demonstrate the suitability of the elastic foundation approach to modeling sea floor interaction in numerical programs.During my initial three years of study I was supported by an Office of Naval Research Graduate Fellowship. More recently, including the time spent on the research described in this thesis, I have been supported by the Office of Naval Research under grant numbers N00014-92-J-1269 and N00014-97-1-0583

Understanding oral reading fluency among adults with low literacy: Dominance analysis of contributing component skills

The final publication is available at Springer via http://dx.doi.org/10.1007/s11145-011-9322-y.This study extends the literature on the component skills involved in oral reading fluency. Dominance analysis was applied to assess the relative importance of seven reading-related component skills in the prediction of the oral reading fluency of 272 adult literacy learners. The best predictors of oral reading fluency when text difficulty was fixed at a single reading level was word reading efficiency. When text difficulty varied based on readers’ comprehension levels, word reading efficiency was also the best predictor with vocabulary and auditory working memory emerging as important predictors as well. Our findings suggest the merit of investigations into whether adults with low literacy may need vocabulary and auditory working memory strategy interventions to improve their reading fluency

Actitudes y conductas públicas ante la COVID-19 en Estados Unidos: estudio de un caso en orden a la comprensión de un sistema político polarizado

How do citizens in a polarized political system react to an unexpected emergency like the COVID-19 pandemic and how do citizens process conflicting polarized narratives to formulate a public policy view of the threat of the pandemic? The emergence of the COVID-19 pandemic is a health emergency unlike anything in the United States since the polio epidemic 70 years ago, but the political climate of the U.S. in the 1950’s was far more centrist and consensual than the deep divisions observed today. This paper will utilize data from a 35-year longitudinal study of Generation X young adults (now in their mid-40’s) and a three-decade time series of national U.S. surveys to examine information acquisition behaviors to understand the new threat. Our analysis of the last 35 years of Generation X finds that polarized ideological partisanship was the strongest single predictor of individual votes in the 2020 election, but that individuals with a higher level of understanding of the coronavirus were more critical of the Trump Administration’s handling of the COVID-19 pandemic and were more likely to vote for Biden than Trump. A parallel analysis of a national probability sample of U.S. adults in 2020 found the same pattern of influence from ideological partisanship, coronavirus understanding, and assessment of the Trump Administration’s handling of the pandemic. The results indicate that knowledge and understanding can provide a critical balancing effect in an evenly divided polarized political system.¿Cómo reacciona la ciudadanía en un sistema político polarizado ante una emergencia como la pandemia de la COVID-19?, ¿cómo procesa la ciudadanía las narrativas polarizadas que están en conflicto?, y ¿qué imagen se forman de la gestión política de la amenaza de la pandemia? En EE. UU, hay que retrotraerse a la epidemia de la polio de hace 70 años para encontrar una emergencia sanitaria como la pandemia de la COVID-19. No obstante, hay importantes diferencias; en la década de 1950, el clima político de los EE.UU. era mucho más uniforme y consensuado que el actual, profundamente dividido y polarizado. Este trabajo utiliza datos de un estudio longitudinal realizado durante 35 años en personas jóvenes de la Generación X (ahora ya en la cuarentena) y datos provenientes de encuestas realizadas en Estados Unidos durante tres décadas, con el propósito de examinar los patrones de adquisición de la información en la comprensión de una nueva amenaza. Nuestro análisis de los últimos 35 años de la Generación X muestra que, en las elecciones de 2020, el factor predictivo del voto individual que tuvo más fuerza fue una ideología política polarizada, pero, aquellas personas que contaban con una mejor comprensión del coronavirus fueron más críticas con la gestión de la pandemia de la COVID-19 que realizó la administración de Donald Trump y estuvieron más predispuestas a votar por Joe Biden que a votar por Trump. Un análisis paralelo de una muestra probabilística representativa de personas adultas estadounidenses en 2020 reveló el mismo patrón de influencia del partidismo ideológico, la comprensión del coronavirus y la evaluación de la administración de Trump. Los resultados muestran que el conocimiento y la comprensión pueden proporcionar un efecto moderador crítico en un sistema político polarizado y dividido

A compact coastal ocean observing system for Kernel Blitz 2001

In this report we describe a compact, easily deployed, moored system for oceanographic and meteorological observations in the coastal ocean. The system consists of a surface and subsurface mooring pair deployed adjacent to one another. Compared to a single catenary surface mooring, this arrangement allows the entire water column to be instrumented. All of the instruments in the system log high resolution time series data. Additionally, the mooring line instruments periodically report averaged data to the buoys via inductive modems. On the subsurface mooring, this averaged data is sent to the surface buoy using an acoustic modem. Inductively coupled mooring line instrumentation includes conductivity, temperature, and pressure sensors, acoustic current meters, and optical backscattering and absorption sensors. In addition to mooring line instruments, the surface buoy collects averaged data from meteorological sensors, including wind speed and direction, barometric pressure, relative humidity, air temperature, precipitation, longwave and shortwave radiation, sea surface temperature and conductivity, and wave height and period. Data from both mooring lines and from the surface meteorological sensors is telemetered to shore via line-of-sight radio and satellite. The entire system, including buoys, moorings, instruments, launch and recovery gear, telemetry receive, and data processing facilities can be packed into a single 20 foot shipping container. The system was successfully deployed to provide environmental monitoring for Kernel Blitz 2001, a US Navy fleet exercise off southern California. Results from the deployment are presented.Funding was provided by the Office of Naval Research under Contract Number N000149910090

An Ambient Pressure Absorption Heat Pump Using Microporous Membranes: Design, Modeling, and Experimental Investigation

A membrane absorption heat pump uses absorbent (a salt solution) and refrigerant (water) flows separated by a membrane to create a temperature difference, or temperature lift, used for heating or cooling. Compared to conventional absorption heat pumps, an ambient-pressure membrane heat pump is built from simpler, more compact, and potentially less expensive components. Storing the absorbent in an unpressurized tank offers unique options for thermal energy storage for solar heating and cooling of buildings and potential applications in long-distance thermal energy transport. The contributions of this thesis can be summarized as: (1) design characterization of this novel process, focusing on controlling the heat and mass transfer in a membrane device for energy storage and transport applications, (2) modeling the process, including detailed analyses of the transport phenomena and a generalized analysis of membrane pore-size distribution, which is applicable to a wide range of membrane processes, and (3) experimental characterization of this process, with validation of the model. Results from a first-principles numerical model shows that using a 1-mm air gap between two membranes gives temperature lifts four times higher than using a single membrane with no air gap. Predicted temperature lifts for the air-gap design range from 5-25 oC, with higher inlet temperatures giving higher temperature lifts. Experimentally measured temperature lifts over a range of flow rates, salt mass fractions, and temperatures match the modeling within 15% with an R-squared of 0.91. The maximum temperature lift achieved was 9 oC, but temperature lifts up to 20 oC are anticipated with a future design using more porous hollow fibers. The detailed analyses of the transport phenomena led to the following conclusions. First, natural convection in the air gap is negligible for the geometries considered here. Second, the membrane\u27s porosity, tortuosity factor, and pore size are adequate to predict membrane mass transfer coefficients, with pore-size distribution having a minimal effect. Third, an accurate estimate of the membrane\u27s effective thermal conductivity is unimportant for modeling a membrane heat pump. Fourth, most of the complex phenomena occurring in the boundary layers are unimportant for predicting the Nusselt and Sherwood numbers for the flows. Experiments on the three prototypes reinforce these conclusions

Cookie Cutting or Gaining a Broader Perspective? Embedding Graduate Attributes in the Curriculum

Objectives: The aim of this project was to increase student awareness of graduate attributes (GAs) at an early stage in their undergraduate career by embedding graduate attribute reflection activities within Level 2 Psychology. Design: Students reflected on how skills gained from their curricular and extra-curricular activities were linked to graduate attributes. Study 1 evaluated the impact of the reflection task by measuring selfefficacy in specific GAs. Study 2 used a mixed-methods design to explore student perspectives on the activities and their views on GAs. Methods: Study 1: Participants were second year psychology undergraduates at the University of Glasgow (N=107). Self-efficacy in each of the dimensions of the University of Glasgow GAs Framework was measured before and after the reflection task, along with measures of self-efficacy in higher education and self-esteem. Study 2: Participants (N= 178) from the same cohort completed the Employability Experience Questionnaire followed by questions about the GAs reflection exercise and their intentions. These questions were discussed in detail in student led focus groups (N= 9). Results: Study 1: Non Parametric analyses indicated that self-efficacy in specific GAs increased after the reflection exercises, and were positively correlated to H.E self-efficacy, and self-esteem. Study 2: Qualitative analysis elicited themes on the “Value of GAs”, “Practicalities”, and “Looking to the Future”. Conclusions: Embedding a GAs reflection task within the psychology curriculum improved students’ self-efficacy, and motivated them to seek further opportunities. Limitations of the design, and implications for skills development in the psychology degree will be discussed

Cookie Cutting or Gaining a Broader Perspective? Embedding Graduate Attributes in the Curriculum

Objectives: The aim of this project was to increase student awareness of graduate attributes (GAs) at an early stage in their undergraduate career by embedding graduate attribute reflection activities within Level 2 Psychology. Design: Students reflected on how skills gained from their curricular and extra-curricular activities were linked to graduate attributes. Study 1 evaluated the impact of the reflection task by measuring selfefficacy in specific GAs. Study 2 used a mixed-methods design to explore student perspectives on the activities and their views on GAs. Methods: Study 1: Participants were second year psychology undergraduates at the University of Glasgow (N=107). Self-efficacy in each of the dimensions of the University of Glasgow GAs Framework was measured before and after the reflection task, along with measures of self-efficacy in higher education and self-esteem. Study 2: Participants (N= 178) from the same cohort completed the Employability Experience Questionnaire followed by questions about the GAs reflection exercise and their intentions. These questions were discussed in detail in student led focus groups (N= 9). Results: Study 1: Non Parametric analyses indicated that self-efficacy in specific GAs increased after the reflection exercises, and were positively correlated to H.E self-efficacy, and self-esteem. Study 2: Qualitative analysis elicited themes on the “Value of GAs”, “Practicalities”, and “Looking to the Future”. Conclusions: Embedding a GAs reflection task within the psychology curriculum improved students’ self-efficacy, and motivated them to seek further opportunities. Limitations of the design, and implications for skills development in the psychology degree will be discussed