Effect of silica fume additions on the hydration behaviour of calcium aluminates

In the recent refractory castables technology, the calcium aluminate cement is being replaced in increasing proportion by very fine matrix components, such as silica fume and colloidal alumina. More efficient particle packing and the resulting lower water requirements have been the proposed explanation for the improved green density and strength, without sacrificing the castable workability. However, the aluminates are still responsible for the hydraulic setting of the castable. The hydration mechanisms of single calcium aluminates, and mixtures thereof, synthesised by combustion reaction of the appropriate nitrate-urea mixtures, were recently investigated. The present work describes the effect of silica time additions on the hydration behaviour of pure single calcium aluminates, also produced by combustion reaction. Results on the hydration mechanisms, the microstructure development and the resulting physical and/or mechanical properties of the hydrated samples, as a tiction of the water/cement ratio and the silica content, me presented and discussed.JNICT-Portugal - PALOP/24

Villaggi industriali in Lombardia tra passato e futuro

In occasione del convegno internazionale organizzato dalla Facoltà di Ingegenria dell'Università di Salerno "Le case e i luoghi del lavoro. Letture e confronti" la scrivente ha presentato una ricerca inedita sui villaggi industriali realizzati in Lombardia tra la fine dell'Ottocento e gli inizi del Novecento in quanto questi rappresentano casi esemplari di organizzazione di nuclei abitati comprensivi dell'area residenziale e di quella della fabbrica. Il villaggio di Crespi d'Adda in provincia di Bergamo mantiene intatti i caratteri originari ed è già patrimonio culturale, ma in molti altri villaggi industriali non è più attiva la produzione della fabbrica e la riconversione dello stabilimento comporta inevitabilmente una riflessione sulle residenze ad esso connesse. Si illustrano alcuni casi di condizioni al contorno differenti e si presenta in dettaglio il caso di Campione sul Garda dove è in corso un progetto di riqualificazione che implica interventi anche sul sistema infrastrutturale del lago

Dalla ricerca alla norma edilizia: il Piano del colore e della manutenzione della città di Napoli.

Il volume raccoglie ricerche e studi svolti nel Dipartimento di Progettazione Urbana dell'Ateneo Federico II di Napoli, applicati in aree napoletane e campane

Cooling, heating, and power systems energy performance and non-conventional evaluation based on energy use

Cooling, Heating and Power (CHP) systems have been recognized as a key alternative for thermal energy and electricity generation at or near end-user sites. CHP systems can provide electricity while recovering waste heat to be used for space and water heating, and for space cooling. Although CHP technology seems to be economically feasible, because of the constant fluctuations in energy prices, CHP systems cannot always guarantee economic savings. However, a well-designed CHP system can guarantee energy savings, which makes necessary the quantification of non-conventional benefits from this technology in order to offset any economic weakness that can arise as consequence of energy prices. Some aspects that could be included in a non-conventional evaluation are: building energy rating, emission of pollutants, power reliability, power quality, fuel flexibility, brand and marketing benefits, protection from electric rate hikes, and benefits from promoting energy management practices. This study focuses on two aspects: building energy rating and emission reduction of pollutants, related to CHP system energy performance. Two methodologies have been developed in order to estimate the energy related benefits from CHP technology. To determine the energy performance, a model has been developed and implemented to simulate CHP systems in order to estimate the building-CHP system energy consumption. The developed model includes the relevant variables governing CHP systems such as: type and size of the components, individual component efficiencies, system operating mode, operational strategy, and building demand for power, heating, and cooling. The novelty of this model is the introduction of the Building Primary Energy Ratio (BPER) as a parameter to implement a primary energy operational strategy, which allows obtaining the best energy performance from the building-CHP system. Results show that the BPER operational strategy always guarantees energy savings. On the other hand, results from a cost-oriented operational strategy reveal that for critical design conditions, high economic savings can be obtained with unacceptable increment of energy consumption. For Energy Star Rating and Leadership in Energy and Environmental Design (LEED) Rating, results show that CHP systems have the ability to improve both ratings

Investigation of the effects of harmful radiation on type-II strained layer superlattice focal plane arrays operated in the long wave infrared

In-situ exposure of InAs/InAsSb strained layer superlattice focal plane arrays to gamma-rays revealed the possibility of a detector capable of imaging through a total ionizing dose event. Two long wave infrared focal plane arrays were exposed to a Co60 source at dose rates of 60 Rads/s and 70 Rads/s in incremental steps up to a total accumulated dose of 30 kRads. The first device showed no degradation in dark current density with accumulated dose while the second device tested showed a small increase up to 1 kRad and minimal increases with subsequent dose steps. The primary imaging defect in the focal plane arrays with exposure to high energy photons was the appearance of bright pixels. A correlation was made between the number and magnitude of ionization events seen in the material and detector bias. The silicon read-out integrated circuit used with the detector material tested in these experiments began to show significant deterioration near 30 kRads. Two long wave infrared InAs/InAsSb strained layer superlattice focal plane arrays were subjected to several exposures from the fast burst reactor at White Sands Missile Range in NM, with a max fluence of 1 x 1012 neutrons/cm2. The primary effect from a neutron event contributing to a degradation in image quality was an increase in the distribution of dark current density values, which blurs the features of an image. Standard deviation of dark current density measurements for the array increased by 6 x 10-5 A/cm2 which constitutes a 406 % increase in pixel-to-pixel variation. Following an accumulated fluence of 1.6 x 1012 neutrons/cm2 there was an absolute decrease in quantum efficiency of 2 % and a relative increase in noise equivalent differential temperature of 64 plus-minus 225 %. A single long wave infrared focal plane array was operated in a 200 MeV proton beam with dark current density measurements performed at incremental steps for a total accumulated fluence of 2.5 x 1011 protons/cm2. The degradation seen in the focal plane array when exposed to protons confirmed the effects seen with gamma-rays and fast neutrons

Cooling, heating, and power systems energy performance and non-conventional evaluation based on energy use

Cooling, Heating and Power (CHP) systems have been recognized as a key alternative for thermal energy and electricity generation at or near end-user sites. CHP systems can provide electricity while recovering waste heat to be used for space and water heating, and for space cooling. Although CHP technology seems to be economically feasible, because of the constant fluctuations in energy prices, CHP systems cannot always guarantee economic savings. However, a well-designed CHP system can guarantee energy savings, which makes necessary the quantification of non-conventional benefits from this technology in order to offset any economic weakness that can arise as consequence of energy prices. Some aspects that could be included in a non-conventional evaluation are: building energy rating, emission of pollutants, power reliability, power quality, fuel flexibility, brand and marketing benefits, protection from electric rate hikes, and benefits from promoting energy management practices. This study focuses on two aspects: building energy rating and emission reduction of pollutants, related to CHP system energy performance. Two methodologies have been developed in order to estimate the energy related benefits from CHP technology. To determine the energy performance, a model has been developed and implemented to simulate CHP systems in order to estimate the building-CHP system energy consumption. The developed model includes the relevant variables governing CHP systems such as: type and size of the components, individual component efficiencies, system operating mode, operational strategy, and building demand for power, heating, and cooling. The novelty of this model is the introduction of the Building Primary Energy Ratio (BPER) as a parameter to implement a primary energy operational strategy, which allows obtaining the best energy performance from the building-CHP system. Results show that the BPER operational strategy always guarantees energy savings. On the other hand, results from a cost-oriented operational strategy reveal that for critical design conditions, high economic savings can be obtained with unacceptable increment of energy consumption. For Energy Star Rating and Leadership in Energy and Environmental Design (LEED) Rating, results show that CHP systems have the ability to improve both ratings

Customer churn prediction

Customer churn prediction is a critical task for businesses operating in competitive markets, especially in the context of online retail. Identifying customers at risk of leaving a service or product allows businesses to implement proactive retention strategies and maintain long-term profitability. This thesis aims to investigate the factors influencing customer churn in online retail and develop predictive models to anticipate churn behavior. Leveraging machine learning techniques, interpretability, and explainability, this study explores the impact of various customer attributes such as demographic information, purchasing behavior, and satisfaction scores on churn prediction. The analysis uses a comprehensive dataset containing customer attributes, transaction history, and response to marketing campaigns. By employing logistic regression models, gradient boosting models and advanced interpretability techniques such as SHAP (SHapley Additive exPlanations), this research aims to provide actionable insights for businesses to mitigate churn and enhance customer retention strategies in the online retail landscape. The findings highlight the significance of features such as average transaction amount, annual income, and recency of last purchase in predicting customer churn, and demonstrate the superior performance of gradient boosting models over logistic regression models in this context.A previsão de churn de clientes é uma tarefa crítica para empresas que operam em mercados competitivos, especialmente no varejo online. Identificar clientes com risco de abandonar um serviço ou produto permite que as empresas implementem estratégias de retenção proativas e mantenham a lucratividade a longo prazo. Esta tese tem como objetivo investigar os fatores que influenciam o churn de clientes no varejo online e desenvolver modelos preditivos para antecipar o comportamento de churn. Utilizando técnicas de aprendizado de máquina, interpretabilidade e explicabilidade, este estudo explora o impacto de vários atributos de clientes, como informações demográficas, comportamento de compra e pontuações de satisfação, na previsão de churn. A análise utiliza um conjunto de dados abrangente contendo atributos de clientes, histórico de transações e resposta a campanhas de marketing. Ao empregar modelos de regressão logística, gradient boosting e técnicas avançadas de interpretabilidade, como SHAP (SHapley Additive exPlanations), esta pesquisa visa fornecer percepções acionáveis para as empresas mitigarem o churn e aprimorarem as estratégias de retenção de clientes no cenário do varejo online. Os resultados destacam a importância de características como valor médio das transações, renda anual e recência da última compra na previsão de churn de clientes e demonstram o desempenho superior dos modelos de gradient boosting em relação aos modelos de regressão logística neste contexto

Energy transition: microgrids and the impact of self-consumption in Mozambique

This work project aims to describe and analyze the energy transition in Mozambique, specifically the impact that microgrids and self-consumption canhave on the electrification system.In the latest years, energy transition and climate change are one of the most discussed and researched topics.Furthermore, we now find ourselves shifting our energy sources, from fossil fuels to renewable energy because ofclimate change, the negative impact of fossil fuels.Moreover, Mozambique has strong renewable potential that could help increase access to electricity through solar panels, as well as improve the quality of service delivery with the right policies and regulations

Search Marketing e valorizzazione di brand

Nel presente lavoro di tesi viene elaborato un algoritmo matematico di analisi della reputazione di brand. Alla modellazione nell' algoritmo si accompagna la descrizione dell' intervento gestionale effettuato all' interno dell' azienda per renderlo operativo ed efficiente