172 research outputs found
Development of miniature all-solid-state potentiometric sensing system
No full textA procedure for the development of a pen-like, multi-electrode potentiometric sensing platform is described. The platform comprises a seven-in-one electrode incorporating all-solid-state ion-selective and reference electrodes based on the conductive polymer (poly(3,4-ethylenedioxythiophene) (PEDOT)) as an intermediate layer between the contacts and ion-selective membranes. The ion-selective electrodes are based on traditional, ionophore-based membranes, while the reference electrode is based on a polymer membrane doped with the lipophilic salt tetrabutyl ammonium tetrabutyl borate (TBA-TBB). The electrodes, controlled with a multichannel detector system, were used for simultaneous determination of the concentration of Pb2+ and pH in environmental water samples. The results obtained using pH-selective electrodes were compared with data obtained using a conventional pH meter and the average percent difference was 0.3%. Furthermore, the sensing system was successfully used for lead-speciation analysis in environmental water samples
New Stationary Frame Control Scheme for Three Phase PWM Rectifiers Under Unbalanced Voltage Dips Conditions
No full textA new stationary frame control scheme for three-phase pulsewidth-modulation (PWM) rectifiers operating under unbalanced voltage dips conditions is proposed in this paper. The proposed control scheme regulates the instantaneous active power at the converter poles to minimize the harmonics of the input currents and the output voltage ripple. This paper's novelty is the development of a new current-reference generator implemented directly in stationary reference frame. This allows using proportional sinusoidal signal integrator (P-SSI) controllers for simultaneous compensation of both positive and negative current sequence components. No phase-locked loop (PLL) strategies and coordinate transformations are needed for the proposed current-reference generator. Experimental results are presented for a 20-kV A alternative current (ac)/direct current (dc) converter prototype to demonstrate the effectiveness of the proposed control scheme. A comparison with two other existing control techniques is also performed. Fast dynamic performance with small dc-link voltage ripple and input sinusoidal currents are obtained with this control scheme, even under severe voltage dips operating condition
Risk Factors for Severe Postoperative Complications after Oncologic Right Colectomy: Unicenter Analysis
No full textBackground and Objectives: This study aimed to investigate the potential risk factors for severe postoperative complications after oncologic right colectomy. Materials and Methods: All consecutive patients with right colon cancer who underwent right colectomy in our department between 2016 and 2021 were retrospectively included in this study. The Clavien–Dindo grading system was used to evaluate postoperative complications. Univariate and multivariate logistic regression analyses were used to investigate risk factors for postoperative severe complications. Results: Of the 144 patients, there were 69 males and 75 females, with a median age of 69 (IQR 60–78). Postoperative morbidity and mortality rates were 41.7% (60 patients) and 11.1% (16 patients), respectively. The anastomotic leak rate was 5.3% (7 patients). Severe postoperative complications (Clavien–Dindo grades III–V) were present in 20 patients (13.9%). Univariate analysis showed the following as risk factors for postoperative severe complications: Charlson score, lack of mechanical bowel preparation, level of preoperative proteins, blood transfusions, and degree of urgency (elective/emergency right colectomy). In the logistic binary regression, the Charlson score (OR = 1.931, 95% CI = 1.077–3.463, p = 0.025) and preoperative protein level (OR = 0.049, 95% CI = 0.006–0.433, p = 0.007) were found to be independent risk factors for postoperative severe complications. Conclusions: Severe complications after oncologic right colectomy are associated with a low preoperative protein level and a higher Charlson comorbidity index
Neke tipološke oznake na slavonskim banskim denarima kovanim za Stjepana V. (1270.-1272.)
No full textThe author studies Slavonian banal denars minted by King Stjepan V (1270-1272). He devotes special attention to the obverse of these coins, the text of the legend. He notices a degree of typification of mint marks and certain letters in the text of these denars.Autor se u ovom radu bavi proučavanjem slavonskih banskih denara kovanih za Stjepana V. (1270.-1272.). Posebnu pozornost pridao je licu tih kovanica, odnosno tekstu legende. Uočio je određenu tipizaciju u kovničkim oznakama unutar teksta, a i pojedinih slova na tim denarima
Maximum power point tracking under realistic operating conditions
No full textThe process of tracking the Maximum Power Point (MPP), known as MPPT, becomes problematic under realistic operating conditions due to the potential for there to be more than one local maxima. A very detailed physics based model has been developed for a PV module (in this application a PV roof tile) using the Orcad platform for PSpice. This model is unusual in that it properly represents partial module shading and cell temperature variation. The PV roof tile, based on polycrystalline silicon cells, comprises 18 series-connected cells. In the model, each cell is represented by a standard two-diode sub-model, for which different levels of radiation and cell temperature can be simulated to obtain a realistic overall I-V characteristic for the module. The model can be extended to model any reasonable number of PV roof tiles wired in series and parallel to form a roof array. The IV characteristics calculated in this way using PSpice will be validated using an outdoor PV roof test system located at the University of Strathclyde, Glasgow
Cultural Adaptation of the Expectancy-Value-Cost Scale for Spanish-Speaking Students
No full textThe Expectancy-Value model has been extensively used to understand students' achievement motivation. However, recent studies propose the inclusion of cost as a separate construct from values, leading to the development of the Expectancy-Value-Cost model. This study aimed to adapt Kosovich et al.’s (The Journal of Early Adolescence, 35, 5–6, 2015) instrument for assessing achievement motivation in science and math among Spanish-speaking students aged 9–12. The psychometric evaluation encompassed examining validity, reliability, and measurement invariance for gender. The findings support the applicability of the expectancy-value-cost model in elementary school students, providing a valid and reliable tool for assessing achievement motivation in the science and math domain. However, the findings for the measurement invariance for gender are less conclusive and warrant future psychometric evaluations. This study opens avenues for future research on achievement motivation in Spanish-speaking contexts and populations.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the Agencia Estatal de Investigación (PID2020-117348RB-I00)
Web Application for Graphical Description and Execution of Spark Tasks
No full textTáto diplomová práca sa zaoberá problematikou spracovania Big data v distribuovanom systéme Apache Spark pomocou nástrojov, ktoré umožňujú vzdialené zadávanie a spúšťanie Spark úloh cez webové rozhranie. Autor v prvej časti opisuje prostredie Apache Spark, v ďalšej sa zameriava na projekt Apache Livy, ktorý ponúka REST API pre spúšťanie Spark úloh. Následne sú predstavené súčasné riešenia, ktoré umožňujú interaktívnu analýzu dát. Autor ďalej popisuje vlastný návrh aplikácie pre interaktívne zadávanie a spúšťanie Spark úloh, pomocou grafovej reprezentácie úlohy. Autor v návrhu popisuje nielen webovú časť aplikácie, ale aj serverovú časť aplikácie. Ďalej implementáciu oboch častí a v neposlednom rade demonštráciu dosiahnutého výsledku na typickej úlohe. Vytvorená aplikácia poskytuje intuitívne rozhranie pre pohodlnú prácu s prostredím Apache Spark, vytváranie vlastných komponent a k tomu aj radu ďalších možností, ktoré sú v dnešnom svete webových aplikácií štandardom.This master's thesis deals with Big data processing in distributed system Apache Spark using tools, which allow remotely entry and execution of Spark tasks through web inter- face. Author describes the environment of Spark in the first part, in the next he focuses on the Apache Livy project, which offers REST API to run Spark tasks. Contemporary solutions that allow interactive data analysis are presented. Author further describes his own application design for interactive entry and launch of Spark tasks using graph repre- sentation of them. Author further describes the web part of the application as well as the server part of the application. In next section author presents the implementation of both parts and, last but not least, the demonstration of the result achieved on a typical task. The created application provides an intuitive interface for comfortable working with the Apache Spark environment, creating custom components, and also a number of other options that are standard in today's web applications.
Characteristics of The Plautine Comic in Pseudolus
No full textTitus Maccius Plautus did not write an original work. The author from Sarsina himself acknowledged the Greek model of his plays. The ancients did not have a cult for originality, the way modernists do and Plautus makes no exception. All that the playwright aims to, regardless of the form, is laughter: “It is a comedy full of charm and humor: / You will roll in the aisles” . Through the analysis of “Pseudolus”, we have tried to outline several characteristics of ludus comicus, of the artistic modality to accomplish it, by the means of which the author from Sarsina managed to assert his uniqueness.ludus comicus, comic, Titus Maccius Plautus
THE IMPACT OF ACCESSION TO THE EUROPEAN UNION ON PERCEPTIONS RELATED TO BUSINESS RISKS IN CENTRAL AND EASTERN EUROPE. A DISTANCE-TYPE ANALYSIS
No full textThe purpose of this paper is to investigate the impact of 2004 accession to the European Union on perceptions related to business risks in Central and Eastern European countries. The investigation makes use of the data provided by the Regular Reports on Global Competitiveness published annually by the World Economic Forum. Methodologically, our analysis requires the estimation of an average for the core of 15 member states of the European Union (EU 15) for each individual pillar considered to describe properly the business environment. In doing so, it is possible to measure the convergence – in terms of a distance-type analysis – of the new member states with the average of EU 15, prior and after the accession, comparatively. In addition, based on a k-means clustering technique, we investigate similarities between the same countries, as well as the convergence of different groups of countries with the group which contains this average.business risk, convergence, clusters, Eastern European Enlargement
Fibers and fabrics for chemical and biological sensing
No full textWearable sensors can be used to monitor many interesting parameters about the wearer’s physiology and environment, with important applications in personal health and well-being, sports performance and personal safety. Wearable chemical sensors can monitor the status of the wearer by accessing body fluids, such as sweat, in an unobtrusive manner. They can also be used to protect the wearer from hazards in the environment by sampling potentially harmful gas emissions such as carbon monoxide. Integrating chemical sensors into textile structures is a challenging and complex task. Issues which must be considered include sample collection, calibration, waste handling, fouling and reliability. Sensors must also be durable and comfortable to wear. Here we present examples of wearable chemical sensors that monitor the person and also their environment. We also discuss the issues involved in developing wearable chemical sensors and strategies for sensor design and textile integration
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