A history of the board of health of the city of New Bedford, Massachusetts

Thesis (Ed.M.)--Boston Universit

Front converter lenses for smart phones

Front converters for the iPhone 6, from six different vendors, are examined in detail. Telephoto, wide angle, and fisheye converters are examined. System performance is measured, and the measured lens designs are presented. Great variety is found in both design type and performance; little correlation is found between performance and design type

Studies of electronic structure of novel phenomena using magnetic compton scattering

In this thesis the spin densities of three groups of materials are investigated, these are GdCo

Unsettling Play: Perceptions of Agonistic Games

In this paper, we propose Agonistic Games (AGs) as a serious games subcategory that can stimulate critical reflection on topics of dark heritage through multiperspectivity and unsettling play. We first discuss the emerging topic of agonism in memory studies, and then how games can be used to support its objectives. We then discuss the development of 2 original AGs: Endless Blitz and Umschlagplatz '43. We explore whether these two AGs were perceived as capable of stimulating critical reflection by collecting data from visitors to the exhibition 'Krieg. Macht. Sinn' at the Ruhr Museum in Germany where the games were installed, and from participants in an online course describing the games. From analysing data collected, we outline four factors inhibiting the capacity of AGs to stimulate critical reflection (topic, context, design, and assumptions about games) and propose strategies for overcoming these inhibitors. Our findings are valuable to scholars, game researchers, and designers, strengthening the foundations for the design and development of future AGs

Multi-temperature state-dependent equivalent circuit discharge model for lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries are described extensively in the literature, but existing computational models aimed at scientific understanding are too complex for use in applications such as battery management. Computationally simple models are vital for exploitation. This paper proposes a non-linear state-of-charge dependent Li-S equivalent circuit network (ECN) model for a Li-S cell under discharge. Li-S batteries are fundamentally different to Li-ion batteries, and require chemistry-specific models. A new Li-S model is obtained using a ‘behavioural’ interpretation of the ECN model; as Li-S exhibits a ‘steep’ open-circuit voltage (OCV) profile at high states-of-charge, identification methods are designed to take into account OCV changes during current pulses. The prediction-error minimization technique is used. The model is parameterized from laboratory experiments using a mixed-size current pulse profile at four temperatures from 10 °C to 50 °C, giving linearized ECN parameters for a range of states-of-charge, currents and temperatures. These are used to create a nonlinear polynomial-based battery model suitable for use in a battery management system. When the model is used to predict the behaviour of a validation data set representing an automotive NEDC driving cycle, the terminal voltage predictions are judged accurate with a root mean square error of 32 mV

Developing A Community Of Practice Through Learning Climate, Leader Support, And Leader Interaction

The Communities of Practice (CoP) concept and the knowledge management literature both provide useful frameworks for conceptualizing how an individual’s performance in the classroom (e.g., earning a grade) or in an organization (e.g., solving a client’s problem) can be supported by a collection of other individuals performing similar tasks and pursuing similar goals. When individuals in a CoP report high levels of meaning, involvement, identification, and belongingness to the community (Wenger, 1998) the individuals act “as resources to each other exchanging information, making sense of situations, sharing new tricks and new ideas, as well as keeping each other company and spicing up each other’s working days” (Wenger, 1998, p. 47). In this paper, we report the results of a study that identifies three factors (learning climate, leader support and leader interaction) that impact the development of a CoP. Specifically, among a sample of 94 undergraduate business students in two cohort groups participating in a year-long program, we found that meaning and involvement were related to leader interaction in a positive manner, identification was related to leader support and CoP climate in a positive manner, and belongingness was related to leader support and leader interaction in a positive manner. Implications are presented for practitioners and educators who wish to facilitate the development of a Community of Practice

Front converter lenses for smart phones

Front converters for the iPhone 6, from six different vendors, are examined in detail. Telephoto, wide angle, and fisheye converters are examined. System performance is measured, and the measured lens designs are presented. Great variety is found in both design type and performance; little correlation is found between performance and design type

A Stochastic Sequential Quadratic Optimization Algorithm for Nonlinear Equality Constrained Optimization with Rank-Deficient Jacobians

A sequential quadratic optimization algorithm is proposed for solving smooth nonlinear equality constrained optimization problems in which the objective function is defined by an expectation of a stochastic function. The algorithmic structure of the proposed method is based on a step decomposition strategy that is known in the literature to be widely effective in practice, wherein each search direction is computed as the sum of a normal step (toward linearized feasibility) and a tangential step (toward objective decrease in the null space of the constraint Jacobian). However, the proposed method is unique from others in the literature in that it both allows the use of stochastic objective gradient estimates and possesses convergence guarantees even in the setting in which the constraint Jacobians may be rank deficient. The results of numerical experiments demonstrate that the algorithm offers superior performance when compared to popular alternatives

Carbon monoxide poisoning: novel magnetic resonance imaging pattern in the acute setting

The presentation of carbon monoxide (CO) poisoning is non-specific and highly variable. The diagnosis is made when a compatible history and examination occur in a patient with elevated carboxyhaemoglobin levels. The severity of intoxication is difficult to assess accurately based on laboratory markers alone. Magnetic resonance imaging (MRI) has been shown to have superior sensitivity to computed tomography for the detection of abnormalities post CO poisoning. We report a novel imaging pattern on MRI undertaken in the acute setting in a patient with CO intoxication. We also discuss the management and follow up of patients with CO poisoning

Lithium-sulfur cell equivalent circuit network model parameterization and sensitivity analysis

Compared to lithium-ion batteries, lithium-sulfur (Li-S) batteries potentially offer greater specific energy density, a wider temperature range of operation, and safety benefits, making them a promising technology for energy storage systems especially in automotive and aerospace applications. Unlike lithium-ion batteries, there is not a mature discipline of equivalent circuit network (ECN) modelling for Li-S. In this study, ECN modelling is addressed using formal ‘system identification’ techniques. A Li-S cell’s performance is studied in the presence of different charge/discharge rates and temperature levels using precise experimental test equipment. Various ECN model structures are explored, considering the trade-offs between accuracy and speed. It was concluded that a ‘2RC’ model is generally a good compromise, giving good accuracy and speed. Model parameterization is repeated at various state-of-charge (SOC) and temperature levels, and the effects of these variables on Li-S cell’s ohmic resistance and total capacity are demonstrated. The results demonstrate that Li-S cell’s ohmic resistance has a highly nonlinear relationship with SOC with a break-point around 75% SOC that distinguishes it from other types of battery. Finally, an ECN model is proposed which uses SOC and temperature as inputs. A sensitivity analysis is performed to investigate the effect of SOC estimation error on the model’s accuracy. In this analysis, the battery model’s accuracy is evaluated at various SOC and temperature levels. The results demonstrate that the Li-S cell model has the most sensitivity to SOC estimation error around the break-point (around 75% SOC) whereas in the middle SOC range, from 20% to 70%, it has the least sensitivity