1,720,953 research outputs found
Modellbasierte elektronische Regelungseinrichtung zur Lagerung und zum Transport von frischem Obst und Gemüse unter modifizierter O₂- und CO₂-Atmosphäre
No full textEfficient storage and transport of fresh produce are critical for maintaining product quality and minimising postharvest losses across the supply chains. Temperature fluctuations and package/container gas compositions, particularly of oxygen (O2) and carbon dioxide (CO2), can accelerate respiration, leading to spoilage and economic loss. Existing controlled atmosphere systems often rely on gas sensors, complex control units and infrastructure, making them economically unfeasible for low-cost storage or transport applications. Modified Atmosphere (MA) systems, including perforated packages and membrane-based storage boxes, are ineffective under dynamic/variable environmental conditions, such as temperature, O2 and CO2 composition, as they are unable to modify the gas transmission rates or their permeability in real-time. This study addressed this gap through the development and validation of a stand-alone, compact, microcontroller-based gas control system that dynamically regulated dual gases such as O2 and CO2 without the need for gas sensors or external gas cylinders, making it suitable for MA storage and transport of different types of fruit and vegetables. The system includes a miniature air blower and tube for fresh air exchange to regulate O2, a second blower to direct air through a soda-lime reactor within the box for CO2 removal, and a thermistor to monitor the fresh produce temperature. A Teensy microcontroller was used to run a temperature-dependent mathematical model to predict the respiration rate of the stored produce and calculate the required blower ON frequency (BOF) for both O2 and CO2 control. An e-paper display provided real-time updates of temperature, predicted gas concentrations and respiration rate. The research was structured into four hypotheses. The first hypothesis included the development of a mathematical model to predict respiration rates based on dynamic temperature and gas composition. This model integrated the Arrhenius equation to capture the effects of temperature, the Michaelis–Menten kinetics to describe O2 dependence and an uncompetitive inhibition term to test the influence of CO2. The internal gas composition was governed by the mass balance of gases between the fresh produce respiration and the blower airflow. This model enabled the calculation of blower ON time to regulate O₂ concentration in real-time based on fresh produce temperature inside the box. Experimental validation using 25 kg of broccoli in a 190L box demonstrated that the system could maintain O₂ at 3.8 ± 0.29% under fluctuating temperatures (4–23°C) for 8 days, while also preserving product quality with minimal weight loss (<3%) and acceptable color change (ΔE < 5). The second hypothesis focused on evaluating the model’s sensitivity in regulating the O2 concentration. It investigated the effect of variations in key parameters, including product respiration rate, supply chain temperature, gas diffusion rate, product mass and storage volume, on the model’s performance and stability in maintaining O2 within the storage/transport box. Monte Carlo simulations revealed that over 80% of BOF variability was driven by just a few key parameters, particularly product weight and respiration rate. The sensitivity analysis identified the most influential parameters, which affected BOF values, and BOF followed a normal distribution with a mean of 47.84 ± 3.69 seconds, highlighting the need to prioritize these factors. Despite the variability, the system maintained O2 concentration at 3.8 ± 0.29 % and CO2 at 14.4 ± 0.66 % and proved the robustness of the model using the validation experiment, containing a 70-litre box with 16 kg of broccoli. The sensitivity analysis paved the way for the development of a respiration model using minimal-data with only impactful parameters, with fewer experiments for their estimation, to make it easy for practical application in the real-time supply chain. The elevated CO2 concentration observed in the storage box prompted the need to find out the control mechanism for CO2. The third hypothesis involved integrating a CO₂ control strategy using soda-lime in an active adsorption reactor. CO₂ adsorption kinetics were modelled using the Weibull function, with temperature dependence described by the Arrhenius equation. Experiments showed that soda-lime maintained CO₂ levels at 4.3 ± 1.8% in a 70L box containing 16 kg of broccoli, provided relative humidity was maintained above 80%. Moisture availability and temperature were found to significantly influence the reaction rate and adsorption efficiency. The final hypothesis combined O2 and CO2 control in a single system, tested on 30 kg of apples over 21 days under dynamic temperatures (5–23°C). The respiration model with minimal-data approach required only four experiments for parameter estimation and proved effective. The system automatically maintained O2 at 1.9 ± 0.4% and CO2 at 3.0 ± 0.5% without gas sensors and generators, by dynamically adjusting the blower operation. This research offered a scalable, gas sensor-independent, moderately precise MA system for dynamic control of O2 and CO2 for extending produce freshness during storage and transport. The approach can be extended to different commodities by adjusting for respiration parameters and CO₂ sensitivity.Eine effiziente Lagerung und der Transport von frischem Obst und Gemüse sind entscheidend für die Erhaltung der Produktqualität und die Minimierung posternterlicher Verluste entlang der Lieferkette. Temperaturschwankungen sowie die Gaszusammensetzung innerhalb von Verpackungen oder Containern, insbesondere der Sauerstoff- (O2) und Kohlendioxid- (CO2) Gehalt, können die Atmung beschleunigen und dadurch Verderb sowie wirtschaftliche Verluste verursachen. Bestehende kontrollierte Atmosphärensysteme basieren häufig auf Gassensoren, komplexen Steuereinheiten und umfangreicher Infrastruktur, was sie für kostengünstige Lager- oder Transportanwendungen wirtschaftlich unattraktiv macht. Systeme der modifizierten Atmosphäre (MA), wie perforierte Verpackungen oder membranbasierte Lagerboxen, sind unter dynamischen bzw. variablen Umgebungsbedingungen (Temperatur, O2- und CO2-Konzentration) ineffektiv, da sie ihre Gastransmissionsraten oder Permeabilitäten nicht in Echtzeit anpassen können. Diese Studie schließt diese Lücke durch die Entwicklung und Validierung eines autarken, kompakten, mikrocontrollerbasierten Gasregelsystems, das eine dynamische Regelung von zwei Gasen (O2 und CO2) ohne den Einsatz von Gassensoren oder externen Gasflaschen ermöglicht und sich somit für die MA-Lagerung und den Transport verschiedener Obst- und Gemüsearten eignet. Das System umfasst einen Miniatur-Luftgebläse mit Schlauch zur Frischluftzufuhr zur O2-Regelung, ein zweites Gebläse zur Führung der Luft durch einen Soda-Lime-Reaktor innerhalb der Box zur CO₂-Entfernung sowie einen Thermistor zur Überwachung der Produkttemperatur. Ein Teensy-Mikrocontroller führte ein temperaturabhängiges mathematisches Modell aus, um die Atmungsrate der gelagerten Produkte vorherzusagen und die erforderliche Einschaltfrequenz der Gebläse (Blower ON Frequency, BOF) für die Regelung von O2 und CO2 zu berechnen. Ein E-Paper-Display stellte Echtzeitinformationen zu Temperatur, vorhergesagten Gaskonzentrationen und Atmungsrate dar. Die Forschung wurde anhand von vier Hypothesen strukturiert. Die erste Hypothese umfasste die Entwicklung eines mathematischen Modells zur Vorhersage der Atmungsrate in Abhängigkeit von dynamischer Temperatur und Gaszusammensetzung. Das Modell integrierte die Arrhenius-Gleichung zur Beschreibung des Temperatureinflusses, die Michaelis-Menten-Kinetik zur Darstellung der O2-Abhängigkeit sowie einen unkompetitiven Inhibitionsterm zur Untersuchung des CO2-Einflusses. Die interne Gaszusammensetzung wurde durch eine Massenbilanz zwischen der Atmung des Frischprodukts und dem Luftstrom der Gebläse beschrieben. Dieses Modell ermöglichte die Echtzeitberechnung der Gebläse-Einschaltzeit zur Regelung der O2-Konzentration basierend auf der Produkttemperatur innerhalb der Box. Experimentelle Validierungen mit 25 kg Brokkoli in einer 190-Liter-Box zeigten, dass das System über acht Tage hinweg unter schwankenden Temperaturen (4–23 °C) eine O₂-Konzentration von 3,8 ± 0,29 % aufrechterhalten konnte, während gleichzeitig die Produktqualität mit minimalem Gewichtsverlust (< 3 %) und akzeptabler Farbänderung (ΔE < 5) erhalten blieb. Die zweite Hypothese konzentrierte sich auf die Bewertung der Sensitivität des Modells bei der Regelung der O2-Konzentration. Untersucht wurden die Auswirkungen von Variationen zentraler Parameter, darunter Atmungsrate des Produkts, Temperaturbedingungen in der Lieferkette, Gasdiffusionsrate, Produktmasse und Lagervolumen, auf die Modellleistung und Stabilität. Monte-Carlo-Simulationen zeigten, dass über 80 % der BOF-Variabilität von wenigen Schlüsselfaktoren, insbesondere Produktgewicht und Atmungsrate, bestimmt wurden. Die Sensitivitätsanalyse identifizierte die einflussreichsten Parameter, welche die BOF-Werte beeinflussten, wobei die BOF einer Normalverteilung mit einem Mittelwert von 47,84 ± 3,69 s folgte. Trotz dieser Variabilität konnte das System die O2-Konzentration bei 3,8 ± 0,29 % und die CO2-Konzentration bei 14,4 ± 0,66 % stabil halten. Die Robustheit des Modells wurde zusätzlich durch ein Validierungsexperiment mit einer 70-Liter-Box und 16 kg Brokkoli bestätigt. Die Sensitivitätsanalyse ebnete den Weg für die Entwicklung eines Minimaldaten-Atmungsmodells, das nur die einflussreichsten Parameter erfordert und mit wenigen Experimenten parametrisiert werden kann, wodurch eine praktische Anwendung in Echtzeit-Lieferketten erleichtert wird. Die beobachteten erhöhten CO2-Konzentrationen in der Lagerbox machten die Entwicklung eines gezielten CO2-Regelmechanismus erforderlich. Die dritte Hypothese befasste sich mit der Integration einer CO2-Kontrollstrategie mittels Soda-Lime in einem aktiven Adsorptionsreaktor. Die CO2-Adsorptionskinetik wurde mithilfe der Weibull-Funktion modelliert, wobei die Temperaturabhängigkeit durch die Arrhenius-Gleichung beschrieben wurde. Die Experimente zeigten, dass Soda-Lime bei einer relativen Luftfeuchtigkeit von über 80 % die CO2-Konzentration in einer 70-Liter-Box mit 16 kg Brokkoli bei 4,3 ± 1,8 % halten konnte. Die Verfügbarkeit von Feuchtigkeit und die Temperatur erwiesen sich als entscheidende Faktoren für die Reaktionsgeschwindigkeit und die Adsorptionseffizienz. Die vierte Hypothese kombinierte die O2- und CO2- Regelung in einem einzigen System und wurde mit 30 kg Äpfeln über einen Zeitraum von 21 Tagen unter dynamischen Temperaturen (5–23 °C) getestet. Diese Arbeit stellt ein skalierbares, gassensorunabhängiges und moderat präzises MA-System zur dynamischen Regelung von O2 und CO2 dar, das zur Verlängerung der Frische von Produkten während Lagerung und Transport beiträgt. Der Ansatz kann durch Anpassung der Atmungsparameter und der CO2 Empfindlichkeit auf verschiedene Agrarprodukte übertragen werden
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
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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