1,721,008 research outputs found
Two-step procedure for data-based modeling for inferential control applications
No full textA two-step procedure for building an inferential control model, which uses both historical operation data and plant test data, is proposed. Motivation for using the two types of data is given, and a systematic way to combine them in the model-identification step is proposed. Some potential problems associated with the procedure in practice and their solutions are discussed. The efficacy of the procedure is demonstrated in a case study involving a multicomponent distillation column simulated in HYSYS
Input test signal design and parameter estimation method for the Hammerstein-Wiener processes
No full textWe propose a new parameter estimation method for Hammerstein-Wiener-type processes composed of the input-output nonlinear static functions and a linear dynamic subsystem. A special test signal is designed to separate the identification problems of the linear dynamic subsystem and the output nonlinear static function from that of the input nonlinear static function. Then, the system identification procedure can be significantly simplified: the identification problems of the linear dynamic subsystem and the output nonlinear static function can be solved independently without considering the input nonlinear static function, and the model parameters of the input nonlinear static function can also be estimated analytically without any iterative nonlinear optimization. Furthermore, we develop a new estimation algorithm to identify the linear dynamic subsystem and the output nonlinear static function more efficiently. This algorithm does not need to initialize the model parameters of the output nonlinear static function and reduces the searching space in the iterative nonlinear optimization problem, resulting in more robust and faster convergence and easier initialization in the nonlinear optimization compared to previous approaches
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
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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Modeling and Control of a Microthermal Cycler for DNA Polymerase Chain Reaction
No full textWe have developed a microthermal. cycler composed of a microreactor integrated with a platinum sensor/heater and automation equipment/software such as a data acquisition system, a control program, and a graphical user interface. From the control point of view, we have analyzed the dynamic characteristics of the fabricated microreactor and found some interesting dynamic features. On the basis of the analysis, we suggest an appropriate model structure and estimate the model parameters using the prediction error identification method. Requirements for high-performance operation are discussed, and a nonlinear control strategy is proposed to linearize the nonlinear dynamics of the microthermal cycler. We determine the parameters of the nonlinear controller using the optimal tuning method. The developed microthermal cycler shows excellent control performances and performs a successful DNA polymerase chain reaction.
In situ thermal diagnotics of the micro-PCR system using liquid crystals
No full textA simple, reliable liquid crystal (LC) thermometry of a polymerase chain reaction (PCR) chip that has a microchamber inside the chip and a film heater and a film sensor patterned on the surface is firstly introduced. The silicon-based PCR chip is made by MEMS technology. A non-linear feedback proportional-integral control scheme adjusts the power input of the Pt heater to control the surface temperature of the micro-PCR chip measured by the Pt sensor with an accuracy of less than ±0.1 °C at steady state. We use the LC thermometry to analyze the temperature distribution in the microchamber of the micro-PCR chip. The reflected colors of LC's inside the microchamber are captured through a charge-coupled device (CCD) camera, subsequently analyzed using a hue-based color analysis system. Two LC's of which individual working range is near the typical PCR temperature of 55 °C and 72 °C are calibrated in a constant temperature bath with a resolution of less than ±0.3 °C. While the average microchamber temperature near the annealing temperature is similar to the surface temperature, it is lower than the surface temperature by ca. 1 °C in the range of the extension temperature. Also, the temperature variations along the center of the microchamber, are less than 1.5 ± 0.5 °C and 3 ± 0.3 °C in the range of the annealing and the extension temperature, respectively
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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