Avaliação da compressibilidade de um Nitossolo Vermelho distroférrico sob sistema plantio direto, preparo convencional e mata nativa

Os efeitos do tráfego de máquinas nos atributos do solo de acordo com o tempo de adoção do sistema plantio direto são ainda pouco pesquisados em ambientes tropicais, e muitas dúvidas ainda persistem sobre a variação dinâmica da estrutura do solo e a sua interação com máquinas e equipamentos. Objetivou-se com este estudo avaliar o efeito do tempo de adoção do sistema plantio direto, comparativamente com área de mata nativa e de preparo convencional, usando os modelos de compressibilidade do solo. O estudo foi realizado em um Nitossolo Vermelho distroférrico, sob mata nativa (MN), preparo convencional (PC), plantio direto com um ano (PD1), plantio direto com quatro anos (PD4), plantio direto com cinco anos (PD5) e plantio direto com 12 anos (PD12). Amostras indeformadas e deformadas foram coletadas em duas profundidades (0-5 e 10-15 cm). O tempo de adoção do sistema plantio direto alterou o comportamento compressivo dos solos em ambas as profundidades, por meio das mudanças na pressão de preconsolidação. A profundidade de 0-5 cm apresentou menor capacidade de suporte de carga do que a profundidade de 10-15 cm. A profundidade de 0-5 cm, em todos os sistemas de manejo, mostrou-se mais susceptível à compactação em relação à profundidade de 10-15 cm. Os sistemas de plantio direto e convencional apresentaram a capacidade de suporte de carga crescente na seguinte ordem: PD5 < PD12 < PD1 < PD4 @ PC, para a profundidade de 0-5 cm e para a profundidade de 10-15 cm: MN @ PD12 < PC @ PD4 < PD5, enquanto o sistema PD1 apresentou comportamento diferenciado.

Being ahead of its time the consumer resistance phenomenon: a comparative case study research

As empresas frequentemente negligenciam o fenômeno da resistência dos consumidores, culminando em investimentos em vão que podem comprometer a sustentabilidade financeira da empresa. Em um mundo onde a novidade é solicitada pelo mercado, as empresas impulsionadas por inovação devem perceber se os consumidores estão preparados para receber uma tecnologia disruptiva. Neste cenário, a difusão tecnológica tornou-se um tema importante de debate entre os pesquisadores. A resistência dos consumidores, no entanto, tem sido negligenciada na literatura. Este estudo analisa as características de inovação percepcionáveis que inibem a massa crítica de consumidores a adotar produtos tecnológicos. Além disso, este estudo complementa a literatura atual, fornecendo resultados empíricos e testando a teoria existente. O projeto de pesquisa tem uma abordagem qualitativa de estudo de caso múltiplo, investigando as características mais relevantes de dois produtos tecnológicos disruptivos que foram rejeitados pela maioria dos consumidores, versus outros dois produtos tecnológicos disruptivos que foram positivamente reconhecidos. Os resultados mostram que a compatibilidade com o estilo de vida do cliente constitui o fator mais importante que levanta barreiras para a adoção.

Formação de palhada por braquiárias para adoção do sistema plantio direto

Com o objetivo de avaliar espécies forrageiras para formação de palhada para adoção do sistema plantio direto, foi pesquisado o potencial de Brachiaria decumbens e B. brizantha, comparadas ao milheto (Pennisetum glaucum). As plantas de cobertura foram semeadas em março e conduzidas até novembro (momento do manejo químico). Aos 50, 110 e 250 dias após a semeadura (DAS) foram avaliadas a composição específica das infestantes na cobertura vegetal, a porcentagem visual de cobertura do solo e o acúmulo de massa vegetal seca das coberturas. As braquiárias foram eficientes na formação de palha (acima de 11 tha-1), sendo promissoras para o sistema plantio direto. Também, observou-se densa cobertura do solo, com supressão do desenvolvimento de plantas daninhas, o que não se percebeu com milheto, cujo maior potencial de cobertura do solo e acúmulo (10,5 t ha-1) de massa ocorreu no fim do seu ciclo (110 DAS) e, 3,2 t ha-1 de massa vegetal seca aos 250 DAS. Devido à rápida decomposição da palha de milheto observou-se, também, reinfestação da área por plantas daninhas.

Adoção de tecnologias móveis em empresas do Rio Grande do Norte, Pernambuco e Ceará

One of the best examples of the Information and Communication Technology (ICT) evolutions is on the high capability of storing and processing data into smaller devices, creating a new business condition, the mobility . This mobility in a deeper analysis proposes a business remodeling in many different areas (business segmentations), through the Internet anywhere at any time, allowing managers and researchers to think again their actual models that work nowadays in companies and public institutions, modifying the way internal and external clients can be attended. This thesis analyzes issues on mobile business adoption, technological evolutions and the impacts caused by this new reality the access to information anywhere at any time . This research is exploratory and shows a compilation of similar papers and thesis describing how was conducted the survey within 50 companies in the states of Rio Grande do Norte, Pernambuco and Ceará. The statistics analysis showed the different level of mobile technology usage from simple voice communications to wide band data transmission. The analysis pointed that canonic correlation was the most effective type of analysis to describe the relations among all groups of variables showing which of them are relevant, or not, for mobile technology adoption

Sentidos e perspectivas atribuídos por crianças à sua condição de estar para adoção

Considering the Brazilian current context, where many children are in institutional shelter waiting for adoption, the aim of this study was to know the meaning that sheltered children (whose families had already lost their custody or were in the process of losing it, at the moment of the field work) gave to their adoption condition. The research was carried out with three children in the shelter where they lived, in Natal, Rio Grande do Norte, Brazil. The field work took six months approximately. In order to meet the objective of this research, individual procedures were structuralized using figures and drawing material. With these procedures the children could speak directly or indirectly about the application of the legal measure of institutional shelter, about their lives before the application of this legal measure and what happened since then, and their original families and future perspectives. The content of the procedures was tape recorded and registered in the field work diary. The analysis of the corpus occurred with the Thematic Content Analysis, considering the theoretical methodological perspective of the Net of Meanings approach. The analysis of the corpus showed the ambiguity of the children, who consider good to live in the institution where they are, recognizing the responsibility of the original caregivers for their sheltered condition and, at the same time, they miss their relatives and wish to be with them. The subjects recognize the perspective of adoption and imagine it in a positive way. However, when the children were questioned about what could happen to them in the future, they said that they did not know, expressing uncertainty concerning their destinations

Instrução verbal: solicitar foco de atenção não garante sua adoção e melhor desempenho

The purposes of this study were to investigate a) the effect of redundant and non-redundant instruction on external focus of attention adoption, b) the effect of adopting an external focus of attention on performance in a front crawl swimming task, and c) the effect of redundancy in the wording of a verbal instruction on the above variables. 43 college students (m/f) aged 17 to 46 swam 25 m crawl at maximum speed, once under each of three conditions: without focus instruction (SF), following a focus instruction (CF) and a redundant focus instruction (CFR), in counterbalanced order. For focus adoption control, after completing the task participants were asked about what they had focused on while swimming. As a measure of performance, time and number of strokes were taken and the stroke index was calculated. The results showed that under redundant focus instruction (CFR) condition, 42 % failed to adopt the attentional focus as asked, and following focus (CF) instruction, 23 %. Under CF condition, the frequency of participants that adopted the focus was higher than of those who did not. Performance did not differ significantly among the three conditions (p>0,05). These findings stress the need of manipulation checks in attentional focus research, regarding both performance and motor learning efficiency, as well as the need for further investigation into the relation between instruction extension and performance.

Detailed analysis of a conservative difference approximation for the time fractional diffusion equation

Diffusion equations that use time fractional derivatives are attractive because they describe a wealth of problems involving non-Markovian Random walks. The time fractional diffusion equation (TFDE) is obtained from the standard diffusion equation by replacing the first-order time derivative with a fractional derivative of order α ∈ (0, 1). Developing numerical methods for solving fractional partial differential equations is a new research field and the theoretical analysis of the numerical methods associated with them is not fully developed. In this paper an explicit conservative difference approximation (ECDA) for TFDE is proposed. We give a detailed analysis for this ECDA and generate discrete models of random walk suitable for simulating random variables whose spatial probability density evolves in time according to this fractional diffusion equation. The stability and convergence of the ECDA for TFDE in a bounded domain are discussed. Finally, some numerical examples are presented to show the application of the present technique.

Determination of preventive maintenance lead time using hybrid analysis

The time for conducting Preventive Maintenance (PM) on an asset is often determined using a predefined alarm limit based on trends of a hazard function. In this paper, the authors propose using both hazard and reliability functions to improve the accuracy of the prediction particularly when the failure characteristic of the asset whole life is modelled using different failure distributions for the different stages of the life of the asset. The proposed method is validated using simulations and case studies.

Effective Cell-Centred Time-Domain Maxwell's Equations Numerical Solvers

This research work analyses techniques for implementing a cell-centred finite-volume time-domain (ccFV-TD) computational methodology for the purpose of studying microwave heating. Various state-of-the-art spatial and temporal discretisation methods employed to solve Maxwell's equations on multidimensional structured grid networks are investigated, and the dispersive and dissipative errors inherent in those techniques examined. Both staggered and unstaggered grid approaches are considered. Upwind schemes using a Riemann solver and intensity vector splitting are studied and evaluated. Staggered and unstaggered Leapfrog and Runge-Kutta time integration methods are analysed in terms of phase and amplitude error to identify which method is the most accurate and efficient for simulating microwave heating processes. The implementation and migration of typical electromagnetic boundary conditions. from staggered in space to cell-centred approaches also is deliberated. In particular, an existing perfectly matched layer absorbing boundary methodology is adapted to formulate a new cell-centred boundary implementation for the ccFV-TD solvers. Finally for microwave heating purposes, a comparison of analytical and numerical results for standard case studies in rectangular waveguides allows the accuracy of the developed methods to be assessed.