1,721,229 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Structure-based framework for the design and risk assessment of hydraulic structures, with application to offline flood detention basins
No full textThe design of hydraulic structures for water control is based on the principle of accepting that structures might fail to fulfill their intended purpose as consequence of extreme, yet rare events producing damages. Traditionally, structures are sized to resist to a “design event”, i.e. a hyetograph or hydrograph associated to a fixed probability of occurrence. This implicitly assumes that the probability of structure failure equals that of the hydrological load, although unjustified under general conditions. Indeed, structure failure also depends on the failure mechanism – which is a characteristic of the specific structure and problem at hand – ruling the interaction between the hydrological load and the structure itself. To overcome the limitations of the hydrological design event approach, we provide here a general, consistent, “structure-based” risk framework, for design or risk assessment. The framework combines the multivariate statistical distribution of the hydrological process and the hydraulic response of the structure. Remarkably, it reduces the potential complexity of the problem to the statistical analysis of the univariate probability distribution of the damage, i.e. the consequence of structure failure. The approach is exemplified for an offline reservoir for flood mitigation, by adopting both a simplified routing model and a Monte Carlo procedure based on a detailed hydrodynamic simulation. Results demonstrate the potential of the framework, regardless of the accuracy of the modeling approach adopted for its implementation. Specifically, the framework allows disentangling the roles of the different design parameters involved, by providing clear indications for practitioners
A high-voltage driver for a scanning micromirror
No full textModern micromachining technologies have made it possible to realize cost-effective and high-reliability Micro-Opto-Electro-Mechanical Systems (MOEMS). Among these devices, double axis micromirrors are widely used in optical telecommunication systems and they are becoming more and more popular for many applications towards the realization of high resolution projection displays. This paper presents a high-voltage driver designed for the actuation of a double axis scanning micromirror in a 0.18 μm Bipolar-CMOSDMOS (BCD) technology
A New Physically Based Index to Quantify the Impact of Multiple Reservoirs on Flood Frequency at the Catchment Scale Based on the Concept of Equivalent Reservoir
No full textThe presence of multiple reservoirs in a catchment generally induces the attenuation of flood events, thus mitigating their impact in downstream flood-prone areas. Such mitigation results from the superposition of several contributions, coming from the regulated (i.e., altered by reservoir) or unregulated subcatchments as determined by the reservoirs spatial distribution within the catchment. Understanding how multiple reservoirs affect the probability distribution of flood peak at the catchment scale is a difficult task, requiring a detailed and generally costly hydrologic/hydraulic simulation. We provide here a simple yet physically based mathematical framework to account for the effect of multiple reservoirs, located in series along the main channel, on peak flood quantile at the catchment scale. The framework allows to disentangle the role of the main relevant parameters controlling the system behavior, such as the number of reservoirs, their relative location and relative storage coefficient within the catchment, and a climatic parameter governing rainfall variability in time. The combined effect of the reservoirs in reducing the peak flow is represented by a global index (Formula presented.), which is bounded between zero and unit and it is independent of the return period. The index is based on the concept of equivalent reservoir and is easily calculated by the analytical formulas provided in this study, as function of the above parameters
A non linear ADC for sensor linearization
No full textA successive approximation ADC with nonlinear characteristic is presented as an effective method for sensor linearization. Drastic simplification of the ADC structure was obtained by implementing a piece wise linear approximation of the required non linear curve. The design and simulated performance of an 8-bit prototype, applied to the linearization of a real flow sensor, are presented
On the Effectiveness of LID Infrastructures for the Attenuation of Urban Flooding at the Catchment Scale
No full textThe efficacy of low-impact development (LID) toward the attenuation of urban flood at the catchment scale is still an unsolved question. This work aims at providing insight into the effectiveness of LID at the catchment scale by a simple hydrological modeling approach that allows for an analytical solution. The paper focuses on LID design, investigating the peak discharge at the catchment outlet as a function of the return period of the rainfall event under unaltered and retrofitted conditions. The model captures the most important effects of LID on flood, that is, the temporal shift and attenuation of water discharge and the decrease of water volume conveyed by the drainage network due to increased hydrological losses. It is found that LID is likely more effective in reducing peak discharge at the local scale, while the effectiveness decreases with increasing catchment size. For some configurations, for example, when retrofit is performed in downstream areas, closer to the outlet, LID may even worsen the flood risk. The effectiveness of LID depends on the combination of several factors, including the fractional area covered by the LID infrastructures, their distribution within the catchment, and their hydraulic properties, as compared with the general hydraulic features of the catchment (network dispersion, detention, lag time, etc.). As a consequence, the LID design should be carried out considering all the relevant scales of the problem, from the local one, at which the LID infrastructure is implemented, to the catchment scale, and the discharge at the outlet in particular, in a comprehensive perspective
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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