MITIGATING THE ADVERSE EFFECTS OF INTERNAL LATERAL IMPACTS IN STRUCTURES EQUIPPED WITH FRICTIONAL ISOLATORS

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On Best One-Sided Approximation By Interpolation Polynomials In Space Lp.w(X)

The aim of this article is to obtain the order of convergence of weighted space by interpolation polynomials  on [-pi, pi].  More details can be found in the full paper

Seismic reliability of structures equipped with LIR-DCFP bearings in terms of superstructure ductility and isolator displacement

This research deals with the seismic reliability of non-linear base-isolated structures equipped with Lateral Impact Resilient Double Concave Friction Pendulum (LIR-DCFP) devices. Specifically, exceeding probabilities within the reference lifetime are assessed with respect to both superstructure ductility and isolator displacement demand. The innovative LIR-DCFP bearing has an improved inner slider with an internal gap and is capable to reduce adverse effects of the lateral impact between the inner slider and the restraining rims. The dynamic behavior of the superstructure is represented by a simplified one-degree-of-freedom model describing its lateral response. The isolation system is characterized by a model based on rigid body dynamics also including the lateral impact behavior. A wide parametric analysis is developed for several system properties considering the friction coefficients as relevant random variables. Different sets of natural seismic records able to match conditional spectra for a site in Riverside (California) were selected to consider the aleatory uncertainties of the seismic input. Incremental dynamic analyses were performed to determine the statistics of significant engineering demand parameters and compute probabilities exceeding specific limit states to define fragility curves. Finally, employing seismic hazard curves, the seismic reliability of isolated structures was evaluated. For increasing values of the internal gap, structures equipped with LIR-DCFP devices exhibit better seismic performance with respect to classical DCFP bearings with same size, especially, if the superstructure is designed to behave essentially elastic when the lateral capacity of the isolation level is not reached, or the hardening post-yield stiffness of the superstructure is relatively high. Reductions up to 20% in the exceeding probabilities within 50 years related to the ductility demand are achievable using the suggested LIR-DCFP isolator

Aspectos biológicos e tabela de vida de Uroleucon ambrosiae (Thomas) em função da temperatura

O afídeo Uroleucon ambrosiae (Thomas) é considerado praga em alface de cultivo hidropônico, mas conhecimentos básicos e aplicados que auxiliam no seu controle, são escassos no Brasil. O objetivo do trabalho foi determinar o efeito de diferentes temperaturas a biologia e tabela de vida de U. ambrosiae em alface (Lactuca sativa L.) hidropônica. Ninfas recém-emergidas foram colocadas em discos com 4 cm de diâmetro de folhas de alface hidropôncia cv. Verônica, mantidas em placas de Petri de 5 cm, nas temperaturas de 15, 20 e 25ºC, com 14 h de fotofase e em casa-de-vegetação em microgaiolas com temperatura ambiente. A duração do desenvolvimento de todos os estágios ninfais variou em razão inversa à temperatura. Quando as ninfas foram mantidas em temperaturas de 20ºC ou 25ºC, os períodos de desenvolvimento foram similares; no entanto, na temperatura ambiente de casa-de-vegetação (média diária = 21ºC), diferentes resultados foram observados. A mesma tendência foi observada para os períodos pré-reprodutivo, reprodutivo e pós-reprodutivo. A fertilidade diária e total a 20ºC foi melhor quando comparada com as temperaturas constantes de 15ºC e 25ºC e a da casa-de-vegetação. A maior mortalidade do afídeo foi constatada em condições de casa-de-vegetação. A produção de 1,28 ninfas por fêmea por dia, o tempo necessário para duplicar em número (TD=2,77dias) e capacidade inata de aumentar em número (r m=0,25), foram similares quando esses insetos foram mantidos a 20 e 25ºC. No entanto, a 20ºC valores superiores foram observados para o tempo decorrido entre gerações (T) e para a taxa líquida de reprodução (Ro). Na casa-de-vegetação, apesar do valor de T ter sido próximo ao observado em condições de laboratório, a 20 e 25ºC, os parâmetros taxa reprodutiva líquida (Ro), taxa intrínseca de aumento de população (r m) e taxa finita de aumento (l) foram inferiores, e TD foi superior. Pelos aspectos biológicos e tabela de fertilidade e esperança de vida, a temperatura de 20ºC é a mais favorável para a espécie U. ambrosiae.The aphid Uroleucon ambrosiae (Thomas) is considered a pest of hidroponically-grown lettuce, but basic and applied information on its control are scarce in Brazil. The aim of this study was to determine the effect of different temperatures on biological aspects and life history of U. ambrosiae (Thomas) developing on hydroponic lettuce (Lactuca sativa L.) crop. Newly emerged nymphs were placed on 4-cm discs of hydroponic lettuce, var. Verônica, which were maintained on 5-cm Petri dishes, at temperatures of 15, 20 and 25ºC and 14 h photophase, and inside a greenhouse, within micro-cages at room temperature. The duration of development in all nymphal stages varied inversely to temperature. Nymphs maintained at 20ºC and 25ºC, had similar development period. However, at fluctuating greenhouse temperatures (daily mean = 21ºC), different results were obtained, which was also true for the pre-reproductive, reproductive and post-reproductive periods. Daily and total fertilities at 20ºC were better in comparison to the other treatments. The highest mortality rate of aphids occurred under greenhouse conditions. The production of 1.28 nymphs per female per day, the time needed for the population to double in size (TD=2.77days), and the intrinsic rate of population increase (r m=0.25), were similar for in insects maintained at 20 and 25ºC. On the other hand, time interval between generations (T) and the net reproductive rate (Ro) were higher at 20ºC. In the greenhouse, even though T was similar to laboratory conditions at 20 and 25ºC, the R0, r m and l parameters were lower and TD was higher. Based on biological aspects, fertility and life expectancy tables, constant temperature of 20ºC is the most suitable for U. ambrosiae

Comparative seismic performance of a moment frame equipped with Lateral Impact Resilient Double Concave Frictional devices

This study presents a comparative assessment of the seismic performance of a reinforced concrete moment frame equipped with a new isolator. The Lateral Impact Resilient Double Concave Friction Pendulum (LIR-DCFP) bearing has an enhanced inner slider capable of limiting the magnitude of the lateral impact force generated between the inner slider and the restraining rims of the sliding surfaces. Due to the presence of a plane high-friction interface with an internal gap, the novel isolator has an increased energy dissipation capacity that is activated during the lateral impact. Three isolation systems were considered to evaluate the benefits of using LIR-DCFP devices. One conformed by the suggested isolator, and two composed of classic non-articulated Double Concave Friction Pendulum (DCFP) bearings. The isolation devices were modelled employing a numerical formulation based on rigid body dynamics, capable of accounting for the lateral impact behaviour. The superstructure, a reinforced concrete moment resisting frame designed according to the American ASCE/SEI 7-16 standard, was modelled using beam-column elements considering geometric and material nonlinearities. Furthermore, the degrading behaviour of the building was incorporated using a proper degradation model for both the stiffness and the force. Incremental Dynamic Analyses (IDAs) were performed considering the friction coefficient as a random variable to characterize the statistics of the maximum inter-story responses. With the data generated in the IDAs, fragility curves related to the superstructure performance were constructed. Finally, employing the hazard curve, reliability curves were derived. The superstructure equipped with LIR-DCFP bearings presents better seismic performance than the same building equipped with the same size DCFP isolators. The benefits of using the new isolator are not achieved by increasing the lateral capacity of the classic isolation system

Desarrollo de un sistema alternativo para la implementación de telemedicina mediante internet inalámbrico

En la actualidad las telecomunicaciones desempeñan un papel muy importante en el área médica; los avances tecnológicos y la Internet resultan a menudo herramientas imprescindibles en este campo. Debido a que la accesibilidad a este medio y su uso van en aumento, esta propuesta consiste en desarrollar un sistema que mantenga en constante comunicación al médicoy paciente, mediante la Internet. Al mismo tiempo se brinda un sistema de información médico que contiene datos útiles tanto para el médico como para el paciente. Ciertos sectores del país, los cuales se encuentran abandonados en el aspecto médico son beneficiados con un sistema de información médica. El sistema está enfocado básicamente para aplicar la Telemedicina (Medicina a distancia) en el Ecuador proporcionando al personal médico una manera más moderna y organizada de llevar un historial médico de los pacientes. Además, este sistema será de bastante utilidad para el paciente, especialmente en casos de emergencia, donde su vida puede depender del conocimiento de cierta información de su historia médica y de la comunicación constante con su respectivo especialista

Composição química de taninos vegetais, curtimento e propriedades nos couros

O Brasil é o país que possui o maior rebanho bovino comercial do mundo, e o balanço de exportações de couro vem demonstrando ascensão no número de metros quadrados de couros exportados. No processo produtivo, a etapa de curtimento é de extrema importância para transformar a pele bovina em couros, tornando-a resistente ao ataque de microorganismos, além de conferir enchimento e garantir maior estabilidade hidrotérmica do material. O crescente apelo ambiental pela utilização de materiais renováveis na indústria levou aos taninos vegetais desempenharem papéis importantes como compostos curtentes na indústria coureira. Os taninos são estruturas fenólicas complexas, existindo uma quantidade considerável de parâmetros químicos que podem ser mensurados através de diversas técnicas analíticas. Por outro lado, para os couros, também existem ensaios empregados no produto final, cujo desempenho pode depender do material curtente utilizado. No presente estudo, foram empregados cinco tipos de taninos de maior uso na indústria coureira para avaliação de parâmetros químicos e posterior associação com propriedades nos couros: tanino de acácia, quebracho, castanheiro, mirabolano e tara. Inicialmente, foi realizada uma revisão bibliográfica, a fim de determinar propriedades químicas de maior relevância a serem mensuradas nos taninos no contexto de sua utilização como agentes curtentes. Nesse sentido, elencaram-se os ensaios de determinação de tanantes totais, não-tanantes, sólidos insolúveis, sólidos solúveis, sólidos totais, fenóis totais e massa molecular média para os taninos. Os parâmetros de percentual de sólidos insolúveis, sólidos solúveis não-tanantes e tanantes totais distinguiram bem os grupos de taninos que atravessaram dos que não atravessaram o couro. Assim, pela análise de insolúveis ser a mais simples e direta delas, recomendar-se-ia o seu uso para definir uma faixa de corte para distinguir o desempenho dos taninos no curtimento. A análise de FTIR-UATR foi útil na caracterização e distinção dos taninos nas famílias dos hidrolisáveis e condensados. Os ensaios de temperatura de retração e distensão da flor nos couros também mostraram associação com o atravessamento dos taninos nas peles durante o curtimento. Por fim, a diferença total de cor após exposição à luz UV também foi avaliada para os couros curtidos com os taninos vegetais, sendo que os taninos hidrolisáveis apresentaram uma menor diferença de cor em relação aos condensados.Brazil is the country with the largest commercial cattle herd in the world, and the balance of exports of leather has shown a rise in the number of square meters of exported leather. In the production process, the tanning step is extremely important to transform the skin into leather, making it resistant to the attack by microorganisms, as well as providing filling and assuring greater hydrothermal stability of the material. The increasing environmental approach for the use of renewable materials in the industry has led to vegetable tannins an important role as tanning compounds in the leather industry. Tannins are complex phenolic structures and there are a considerable amount of chemical parameters that can be measured through various analytical techniques to characterize them. On the other hand, for hides, there are also tests used in the final product, whose performance may depend on the tanning material used. In the present study, five types of tannins highly used in the tanning industry were used for the evaluation of their chemical parameters and later correlation with properties in hides: Black Wattle (Acacia mearnsii), Quebracho (Schinopsis lorentzii), Chestnut (Castanea sativa), Tara (Caesalpinia spinosa) and myrabolan (Terminalia chebula). Initially, a bibliographical review was carried out to determine the most relevant chemical properties to be measured in the tannins in the context of their use as tanning agents. In this context, the assays for the determination of total tannin polyphenols, non-tannin polyphenols, insoluble solids, soluble solids, total solids, total phenols and average molecular weight for tannins were performed. FTIR-UATR analysis was useful in characterizing and distinguishing tannins in their families of hydrolysates and condensates. The Mann-Whitney-U test showed that the insoluble solids, non-tannin polyphenols, soluble solids and total tannin polyphenols percentage distinguished well the groups of tannins that crossed the hide from those that didn´t. Hence, once the analysis of insoluble solids is the simplest and the most direct of them, it would be recommended to use this parameter to define a cutting range to distinguish the performance of tannins in leather tanning. The shrinkage temperature and distension tests in the leather also showed association with the leather cross-sectional results during tanning baths. Finally, the total color difference after exposure to UV light was also evaluated for the tanned hides with the vegetable tannins, and the hydrolysable tannins presented a smaller color difference or greater light fastness in comparison to the condensates

EDUCAÇÃO PARA A DEMOCRACIA E CO-EDUCAÇÃO: APONTAMENTOS A PARTIR DA CATEGORIA GÊNERO

EDUCAÇÃO PARA A DEMOCRACIA E CO-EDUCAÇÃO: APONTAMENTOS A PARTIR DA CATEGORIA GÊNER

Demand and capacity management for meal delivery systems

With the recent boom of the gig economy, urban delivery systems have experienced substantial demand growth. In such systems, orders are delivered to customers from local distribution points respecting a delivery time promise. An important example is a restaurant meal delivery system, where delivery times are expected to be minutes after an order is placed. The system serves orders by making use of couriers that continuously perform pickups and deliveries. Operating such a rapid delivery system can be very challenging, primarily due to the high service expectations and the considerable uncertainty in both demand and delivery capacity. In this thesis, we study problems that are based on most recent challenges in meal delivery operations, namely (i) demand management in the form of service area control around restaurants, (ii) capacity management considering the satisfaction of couriers, and (iii) on-demand capacity acquisition based on real-time market signals. To contextualize out work, in Chapter 1 we give an overview of the meal delivery process, and comment on its past success and growth expectations for the future. We also discuss the main operational aspects that make meal delivery a challenging problem in logistics, and then motivate our study on demand and capacity management. In Chapter 2, we seek to answer several questions in meal delivery operations focused on matching the correct levels of supply with demand. In particular, we consider a demand management mechanism in practice used by meal delivery providers to ensure acceptable customer service when the system is low in delivery capacity, which consists on decreasing demand during an operating day by temporarily reducing the delivery area for one or more restaurants. We show that simple demand restriction strategies allow a significantly smaller fleet to meet service requirements. To simplify analysis, we focus on problem geometries that enable the use of stylized mixed integer programs to optimally deploy a fleet of couriers serving large numbers of orders. Applying the proposed framework to several scenarios with one and two depots, we conduct an extensive experimental study of the effects on system performance of (i) allowing courier sharing between multiple depots, (ii) relaxing the delivery deadlines of placed orders, and (iii) restricting demand through limited adjustment of the service area of restaurants. The results demonstrate the potential effectiveness of different dispatch control and demand management mechanisms, in terms of both the required courier fleet size to serve requests and the coverage level of orders. Chapter 3 in turn, is devoted to the study of capacity management by considering courier satisfaction. This is a critical aspect in terms of retention/loyalty in a highly competitive environment. Under the premise that couriers prefer to operate in relatively small geographic areas to increase their efficiency, we propose the novel concept of dynamic courier regions: small operating regions for couriers which can also be dynamically and temporarily expanded to allow delivery capacity to be shared between regions when necessary to keep customer service performance metrics high. We propose an optimization-based rolling horizon algorithm for courier management which handles both region resizing and request assignment decisions. Experimental results for realistic settings show that the proposed algorithm successfully balances customer and courier satisfaction, simultaneously achieving service quality levels that are comparable to those of a single operating region and courier satisfaction metrics that are comparable to those achieved by fixed, inflexible regions. Lastly, in Chapter 4 we study the problem of dynamically adding extra courier capacity in a rapid delivery system. Delivery providers typically plan courier shifts for an operating period based on demand forecast. However, because of the high demand volatility it may at times during the operating period be necessary to adjust and dynamically add couriers. To address this problem, we propose a deep reinforcement learning approach to obtain a policy that balances the cost of adding couriers and the cost of service quality degradation by an insufficient number of couriers. Specifically, we seek to ensure that a high fraction of orders is delivered on time and with a small number of courier hours. A computational study shows that when performing corrective capacity adjustments, a learned policy using the proposed framework outperforms policies representing current practice in the meal delivery space, demonstrating the potential of deep learning for solving operational problems in highly stochastic logistic settings.Ph.D