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Trends in Locally Balanced Energy Systems without the Use of Fossil Fuels: A Review
- Łukasz Mazur
- Sławomir Cieślik
- Stanisław Czapp
2023 Pełny tekst ENERGIES
In recent years, the idea of the operation of energy systems (power systems, heating systems) has changed significantly. This paper is an overview of locally balanced energy systems without the use of fossil fuels. The paper justifies the concept of local energy balancing in a new energy system that does not use fossil fuels (coal, natural gas, and crude oil), based on European Union guidelines and formal documents as well as the literature on the subject. In this context, the issue of local energy self-sufficiency, utilizing renewable energy sources, as well as the concept of local smart grids based on innovative market mechanisms are raised. Attention is also paid to technical issues with regard to locally balanced energy systems, in particular photovoltaic sources and energy storage. Challenges related to the use of electrical protection in networks with many sources of energy are described. In such networks, the power flow is not in one direction only. Moreover, the selection of protections is problematic due to the distribution of short-circuit currents. Additionally, earth fault currents in such networks may be distorted, and this negatively affects the operation of residual current devices. The basic nomenclature describing locally balanced systems has been sorted out as well. Finally, possible future research paths in the field of creating locally balanced systems without the use of fossil fuels are presented.
Triplet Formation and Triplet‐Triplet Annihilation Upconversion in Iodine Substituted Non‐Orthogonal BODIPY‐Perylene Dyads
- Keshav Kumar Jha
- Amrutha Prabhakaran
- Rengel Cane Sia
- Ruben Arturo Arellano-Reyes
- Nirod Kumar Sarangi
- Tingxiang Yang
- Krishan Kumar
- Stephan Kupfer
- Julien Guthmuller
- Tia E. Keyes
- Benjamin Dietzek-Ivanšić
2023 Pełny tekst ChemPhotoChem
BODIPY-perylene dyads have emerged as useful metal free sensitizers for triplet-triplet annihilation upconversion (TTAUC), these dyads are capable of efficient triplet generation via spinorbit charge transfer intersystem crossing (SOCT-ISC). This important route to triplet formation requires dyads in which two moieties are oriented perpendicular to each other. In this contribution, we give a deeper insight on the behavior of recently reported BODIPY-perylene dyads, where BODIPY-perylene dihedral exhibits a non-orthogonal dyad geometry. The intersystem crossing of BODIPY-perylene dyads with and without iodine are investigated using femtosecond transient absorption (fs-TA) and nanosecond transient absorption (ns-TA) spectroscopy. The concurrent decay of the singlet charge transfer state (1CT) and rise of triplet states in both the iodinated and non-iodinated dyads confirms the SOCT-ISC as the main intersystem crossing pathway despite the altered geometry of the dyads. The presence of an iodine atom on the BODIPY-moiety enables intersystem crossing 2.6-times faster and provides a higher triplet yield with respect to dyad without iodine. The upconversion quantum yield is 8.4-times higher in the sample containing iodinated dyad as sensitizer and perylene as annihilator. The triplet-triplet energy transfer rate (kTTET) is ~8×10^8 M-1.s-1 for both iodinated and noniodinated sensitizer containing TTAUC systems in 1,4-dioxane.
Trójfazowy 4-gałęziowy falownik SiC w napędzie z wysokoobrotowym silnikiem indukcyjnym
- Marek Adamowicz
- Sebastian Giziewski
- Zbigniew Krzemiński
2023 Pełny tekst Przegląd Elektrotechniczny
Zastosowanie tranzystorów SiC w falownikach napędów wysokoobrotowych powoduje nowe wyzwania,szczególnie odnośnie generowanego w falowniku napięcia common mode (CM) o wysokiej częstotliwości. Wysokoczęstotliwościowe napięcie CM wchodzi w interakcję z pojemnościami pasożytniczymi falownika, kabla i silnika wymuszając przepływ prądów CM, które są źródłem strat w filtrach pasywnych oraz powodują zakłócenia pomiarów prądów, nieakceptowalne z punktu widzenia działania przekształtnika. Ze wzrostem częstotliwości rośnie poziom emisji zaburzeń elektromagnetycznych spowodowany rezonowaniem obwodu CM, a tym samym niekorzystnie rośnie masa, gabaryt i koszt dławików CM. W referacie zaproponowano zastosowanie 4-gałęziowego falownika SiC z metodą sterowania zapewniającą eliminację napięcia CM celem poprawy właściwości napędu wysokoobrotowego.
Truss imperfections in the design of bar and diaphragm bracing systems
- Natalia Korcz-Konkol
- Piotr Iwicki
2023 Pełny tekst JOURNAL OF CONSTRUCTIONAL STEEL RESEARCH
In the article three variants of roof bracing were considered: bar bracing, diaphragm bracing and the combination of bar and diaphragm bracing. Different analytical and numerical ways of taking into account the imperfections of the truss girder were compared. The entire 3D model of the roof (shell and beam elements with the eccentricities taken into account) was analysed numerically. Selected stressed-skin aspects were considered. Stabilizing forces in the purlins and forces in bracing elements (bar and/or diaphragm bracing, connections) were observed. The importance of the imperfection issues (e.g. shape of the imperfection, method of including imperfection, wind forces) was evaluated numerically to indicate the key points in the design procedure. The biggest forces in purlins occurred for “nonstandard” shape of the imperfection. On the other hand, in case of bracing elements, when wind forces were taken into consideration, “standard” approach of including the imperfection was safe approximation. Moreover, the diaphragm took over significant part of the bracing forces, however the distribution of the forces depended strongly on the flexibility of the bracing and purlin/truss connection.
Trustworthiness and Subversion in Large Service- Oriented Multi-Agent Systems under Virtual Anonymity and Blind Provider Selection
- Jerzy Konorski
2023
To promote honest service provision in multi-agent systems, a Computational Trustworthiness and Rating scheme collects service ratings and computes agents' trustworthiness levels (TLs). Studies of existing schemes fail to reflect closed-loop dynamics of TLs arising from the mutual influence of agents' behavior and TLs, and to capture relevant properties. Recent simulative and analytical models produce results tied to a particular attack scenario, or restricted to small-size systems or simplistic agent behavior. We analyze a class of parameterized skimp and slander attacks in a challenging setting featuring agents' virtual anonymity, collusion, and blind, i.e., TL-insensitive selection of service providers, as well as unpredictable service availability and receptivity. We derive closed-loop Markovian TL dynamics and their mean-value approximation to analytically characterize agents' steady-state TLs, and find a systematic defense against skimp and slander.
Tuning of eg electron occupancy of MnCo2O4 spinel for oxygen evolution reaction by partial substitution of Co by Fe at octahedral sites
- Krystian Lankauf
- Karolina Górnicka
- Patryk Błaszczak
- Jakub Karczewski
- Jacek Ryl
- Grzegorz Cempura
- Marcin Zając
- Maciej Bik
- Maciej Sitarz
- Piotr Jasiński
- Sebastian Molin
2023 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
To study the effect of partial Co substitution by Fe in the B site of MnCo2O4 spinel on its physicochemical and electrochemical properties, a series of MnCo2-xFexO4 powders (x=0.125; 0.250; 0.500; 0.750; 1.000) were synthesized by means of the sol-gel method. The produced powders were characterized by powder X ray diffraction (pXRD), scanning and transmission electron microscopy (SEM & TEM) coupled with energy dispersive spectroscopy (EDS), X ray photoelectron and absorption spectroscopy (XPS & XAS), Fourier transformed infrared spectroscopy (FTIR), and inductively coupled plasma optical emission spectroscopy (ICP OES). The electrocatalytic activity towards oxygen evolution reaction (OER) was evaluated in an alkaline environment (0.1 M KOH). From our findings, the activity increased with the addition of Fe up to x = 0.5, characterized by a decrease of overpotential at 10 mA cm-2GEO from 406 mV for MnCo2O4 to 376 mV for MnCo1.5Fe0.5O4, with a corresponding 44 mV dec 1 Tafel slope. It was identified that the OER-specific activity exhibits a volcano-type shape as a function of the eg occupancy at octahedral sites tuned by Co substitution with Fe.
Tuning of the plasmon resonance location in Au nanostructures coated with a ultrathin film of Al2O3 – Optical measurements and FDTD simulations
- Marcin Łapiński
- Robert Kozioł
- Paweł Syty
- Sergiusz Patela
- Józef Sienkiewicz
- Wojciech Sadowski
- Barbara Kościelska
2023 SURFACE SCIENCE
The Au nanostructures have been coated with an ultra-thin films of amorphous aluminium oxide. Optical absorption spectra show the influence of the thickness of Al2O3 on plasmon resonance wavelength. The observed red-shift of the resonance location with the increase of the thickness of the Al2O3 film, can be explained by the change in the dielectric function of this film. It allows control of the optical spectra of the coated particles. In this paper we present a two ways for determinaton of optical paramaters of aluminium oxide ultra-thin films. The first one is based on a ellipsometry method, while in second approach a shift of plasmon resonance is used for computer simulations of films. The experimental data are in agreement with the results of the FDTD calculations, showing the possibility of both determining such a function for ultra-thin layers by the computer simulation method, as well as predicting the value of the dielectric constant depending on the thickness of the layer. The experimental data needed for the simulation was obtained in studies such as XRD, XPS, SEM and HR TEM. The proposed models can help to adjust the coating thickness to the desired plasmon resonance position.
Tutoring - dlaczego edukacja spersonalizowana ma sens
- Aneta Sobiechowska-Ziegert
- Katarzyna Kubiszewska
2023 Pismo PG
W artykule autorki przedstawiają koncepcję tutoringu akademickiego. Ostatnie lata przyniosły wzmożone zainteresowanie nowymi formami pracy z uczniem. Wielu specjalistów z zakresu edukacji twierdzi, że osiąganie wysokich rezultatów jest możliwe, ale wymaga zindywidualizowanej pracy z drugą osobą. Tutoring wpisuje się właśnie w ten nurt zindywidualizowanej pracy i relacji mistrz - student.
Tweet you right back: Follower anxiety predicts leader anxiety in social media interactions during the SARS-CoV-2 pandemic
- Alexandros Psychogios
- Dritjon Gruda
- Adegboyega Ojo
2023 Pełny tekst PLOS ONE
Recent research has shown that organizational leaders’ tweets can influence employee anxiety. In this study, we turn the table and examine whether the same can be said about followers’ tweets. Based on emotional contagion and a dataset of 108 leaders and 178 followers across 50 organizations, we infer and track state- and trait-anxiety scores of participants over 316 days, including pre- and post the onset of the SARS-CoV-2 pandemic and crisis. We show that although leaders traditionally possess greater authority and power than their followers, followers have the power to influence their leaders’ state anxiety. In addition, this influence is particularly strong in the case of less trait anxious leaders.
Two-body dissociation of isoxazole following double photoionization – an experimental PEPIPICO and theoretical DFT and MP2 study
- Tomasz Wąsowicz
- Iwona Dąbkowska
- Antti Kivimäki
- Robert Richter
2023 Pełny tekst PHYSICAL CHEMISTRY CHEMICAL PHYSICS
The dissociative double photoionization of isoxazole molecules has been investigated experimentally and theoretically. The experiment has been carried out in the 27.5–36 eV photon energy range using vacuum ultraviolet (VUV) synchrotron radiation excitation combined with ion time-of-flight (TOF) spectrometry and photoelectron–photoion–photoion coincidence (PEPIPICO) technique. Five wellresolved two-body dissociation channels have been identified in the isoxazole’s coincidence maps, and their appearance energies have been determined. The coincidence yield curves of these dissociation channels have been obtained in the photon energy ranges from their appearance energies up to 36 eV. The double photoionization of isoxazole produces a C3H3NO2+ transient dication, which decomposes into fragments differing from previously reported photofragmentation products of isoxazole. We have found no evidence of pathways leading to the C3H2NO+, HCN+, C2H2O+, C3HN+, or C2H2 + fragments or their neutral counterparts that have been observed in previous neutral photodissociation and single photoionization studies. Instead, the dissociation of isoxazole after the ejection of two electrons is bond-selective and is governed by two reactions, HCO+ + H2CCN+ and H2CO+ + HCCN+, whose appearance energies are 28.6 (0.3) and 29.4 (0.3) eV, respectively. A third dissociation channel turns out to be a variant of the most intense channel (HCO+ + H2CCN+), where one of the fragment ions contains a heavy isotope. Two minor dissociation channels occurring at higher energies, CO+ + CH3CN+ and CN+ + H3CCO+, are also identified. The density functional and ab initio quantum chemical calculations have been performed to elucidate the dissociative charge-separating mechanisms and determine the energies of the observed photoproducts. The present work unravels hitherto unexplored photodissociation mechanisms of isoxazole and thus provides deeper insight into the photophysics of five-membered heterocyclic molecules containing two heteroatoms.
Udział społeczeństwa w procedurze planowania przestrzennego – analiza metod i technik konsultacji społecznych na przykładzie polskich małych i średnich miast w ramach projektu POWER
- Barbara Zgórska
- Marta Jaskulska
2023 Pełny tekst Space-Society-Economy
Udział społeczeństwa w procesie opracowywania aktów planowania przestrzennego w Polsce ma charakter informacyjny, a nie dialogiczny, co przyczynia się m.in. do jego konfliktogenności. W latach 2016–2021 zrealizowano ogólnokrajowy projekt POWER dofinansowany ze środków Unii Europejskiej, którego celem było m.in. przetestowanie angażujących metod i technik konsultacji społecznych, zwiększenie poziomu współdecydowania i poprawa metod rozwiązywania konfliktów w planowaniu przestrzennym na poziomie gminnym.Artykuł zawiera ocenę metod i technik konsultacyjnych zastosowanych w 83 małych i średnich miastach, które uczestniczyły w projekcie POWER, opis najczęściej wykorzystywanych metod i technik, sposobów ich łączenia oraz trzy studia przypadków analizowanych pod kątem możliwości wyeliminowania potencjalnych konfliktów.Badanie przeprowadzono z wykorzystaniem metod ilościowych i jakościowych: desk research, obserwacja, obserwacja uczestnicząca, ankieta.
UKŁAD REGULACJI MOCY DUŻEJ FARMY FOTOWOLTAICZNEJ
- Mirosław Włas
- Konrad Seklecki
- Kacper Chyła
2023 Pełny tekst
W dniu 17 maja 2016 r. weszło w życie Rozporządzenie Komisji (UE) 2016/631 z dnia 14 kwietnia 2016 r. ustanawiające kodeks sieci dotyczący przyłączenia jednostek wytwórczych [3]. Na podstawie tego dokumentu i Prawa Energetycznego OSP i OSD przygotowało wymogi w zakresie przyłączania jednostek wytwórczych do sieci energetycznej. Moduły wytwarzania B, C i D powinny posiadać możliwość regulacji mocy czynnej i biernej. Niniejszy artykuł przedstawia wdrożenie wymagań Kodeksu Sieci NC RfG dla farmy fotowoltaicznej o mocy 60MWp
Ultra-Compact SIRC-Based Self-Triplexing Antenna with High Isolation
- Rusan Kumar Barik
- Sławomir Kozieł
2023 Pełny tekst Electronics
An ultra-compact self-triplexing antenna realized on a substrate-integrated rectangular cavity (SIRC) is discussed in this study. The proposed structure employs two L-shaped slots and an in-verted U-shaped slot to radiate at three independent operating frequency bands. Three 50-ohm microstrip feed lines are used to excite the radiation in these slots. The operating frequency is individually tuned using the slot size. The slot placement and size are designed having in mind obtaining one or more frequency bands below the SIRC cutoff frequency, which has the ad-vantage of enabling ultra-compact size. High port isolations are achieved by applying one of the ports orthogonally to the two remaining ones, which creates a weak cross-coupling channel. A lumped-circuit model is created to examine the antenna operation. The presented design has been prototyped and experimentally validated with the measured operating frequencies of 1.92 GHz, 4.43 GHz, and 5.25 GHz for GSM, 5G, and WLAN applications, respectively. The port isola-tions are better than 32.4 dB according to both EM simulations and measurements. Meanwhile, the measured realized gain of the antenna is better than 4.3 dBi at all bands.
Ultrasound assisted dispersive solid phase microextraction using polystyrene-polyoleic acid graft copolymer for determination of Sb(III) in various bottled beverages by HGAAS
- Nail Altunay
- Baki Hazer
- Muhammad Farooque Lanjwani
- Mustafa Tuzen
- Hameed Haq
- Grzegorz Boczkaj
2023 FOOD CHEMISTRY
A new polyoleic acid-polystyrene (PoleS) block/graft copolymer was synthesized and applied as adsorbent for ultrasound assisted dispersive solid phase microextraction (UA-DSPME) of Sb(III) in different bottled beverages and analysis using hydride generation atomic absorption spectrometry (HGAAS). Adsorption capacity of the PoleS was 150 mg g−1. Several sample preparation parameters such as sorbent amount, solvent type, pH, sample volume and shaking time were optimized (based on central composite design (CCD) approach) and evaluated in respect to the recovery of Sb(III). The method revealed a high tolerance limit of matrix ions presence. Under optimized conditions, linearity range, the limit of detection, the limit of quantitation, extraction recovery, enhancement factor, preconcentration factor were 5–800 ng L−1, 1.5 ng L−1, 5.0 ng L−1, 96%, 82, 90, respectively. Accuracy of the UA-DSPME method was confirmed based on different certified reference materials and standard addition method. Factorial design was utilized to estimate the influences of variables of recovery of Sb(III).
Uncertainty of Postmortem Time Estimation Based on Potassium Ion Determination in Vitreous Humor Using Potentiometric Ion-Selective Electrode and Microwave-Induced Plasma with Optical Emission Spectrometry Methods
- Sonia Zięba
- Marek Wiergowski
- Bartłomiej Cieślik
- Sein Anand Jacek
- Marta Krzyżanowska
2023 Pełny tekst Separations
There is a need for a reliable and independent evaluation and confirmation of the post-mortem interval (PMI) based on objective factors other than only postmortem changes or temperature measurements. Estimating the PMI by examining the concentration of potassium ions in the vitreous humor (VH) has a tradition in forensic toxicology dating back to the mid-20th century. So far, the methods for determining the presence of potassium ions have not been characterized in terms of the measurement uncertainty of types A and B, which directly affect the estimation of time of death uncertainty. The study evaluated the uncertainty of the determination of potassium ion concentra- tions using potentiometric ion-selective electrode (ISE) and microwave-induced plasma with optical emission spectrometry (MIP-OES) methods. In addition, the influence of the estimated measurement uncertainty on the results of the analysis of potassium ions in the VH was investigated. The estimated values of the expanded uncertainty determined by the type A experimental method indicate lower uncertainty in the determination of potassium ion concentration in the case of MIP-OES than ISE; that is, for concentrations of 2, 10, and 25 mg/L of potassium ions, the expanded uncertainties by MIP-OES were 1.2%, 2.2%, and 2.5% and the uncertainties by ISE were 12.2%, 6.1%, and 3.1%, respectively. Similarly, in the case of estimating the uncertainty of type B, the MIP-OES method compared to ISE was characterized by almost two times lower expanded uncertainty; that is, for MIP-OES, it was 2.53%, and for ISE, it was 4.75%. Both methods of uncertainty estimation, types A and B, can be used interchangeably, as they provide comparable results.
Uncertainty Quantification of Additive Manufacturing Post-Fabrication Tuning of Resonator-Based Microwave Sensors
- Sławomir Kozieł
- Tanveer Haq Ul
2023 MEASUREMENT
Reconfigurability, especially in terms of the ability of adjusting the operating frequency, has become an important prerequisite in the design of modern microwave components and systems. It is also pertinent to microwave sensors developed for a variety of applications such as characterization of material properties of solids or liquids. This paper discusses uncertainty quantification of additive-manufacturing-based post-fabrication tuning of resonator-based sensors implemented using a microstrip technology. Therein, the operating frequency is altered by adding metallic patches of a specific size determined by the full-wave electromagnetic (EM) model of the system. The reliability of setting up the center frequency depends on both the accuracy of the patch size (manually cut out of the copper tape), and its allocation with respect to the resonator. A rigorous statistical analysis of the patch size and its allocation errors is carried out, including a quantification of their joint effects on the sensor operating frequency. Furthermore, the analysis of a possibility of compensating the patch size inaccuracies through its appropriate positioning is conducted. The details of the proposed approach are explained using a complementary symmetric split ring resonator (CSSRR)-based sensor designed to operate in X and Ku bands with the tuning range between 10 GHz and 20 GHz. The optimized sensor's fundamental resonant frequency is 9.4 GHz, its exterior size is 25 x 30 mm2, the quality factor of the fabricated sensor is 29, and the sensitivity of the considered design is 1.1 GHz/mm with the measurement error is 0.1 percent. The obtained measurement data are indicative of a practical utility of the additive-manufacturing-based tuning technique, in particular, a possibility of reliable center frequency tuning under mild assumptions on the accuracy of manual preparation of the tuning patches. Furthermore, a practical tuning scheme has been developed and experimentally validated, which allows for a precise allocation of the operating frequency with the error not exceeding 0.01 GHz (or 0.1% in relative terms), all under assumptions of a manual preparation and placement of the tuning patch.
Underground Water Level Prediction in Remote Sensing Images Using Improved Hydro Index Value with Ensemble Classifier
- Andrzej Stateczny
- Sujatha Canavoy Narahari
- Padmavathi Vurubindi
- Nirmala S. Guptha
- Kalyanapu Srinivas
2023 Pełny tekst Remote Sensing
The economic sustainability of aquifers across the world relies on accurate and rapid estimates of groundwater storage changes, but this becomes difficult due to the absence of insitu groundwater surveys in most areas. By closing the water balance, hydrologic remote sensing measures offer a possible method for quantifying changes in groundwater storage. However, it is uncertain to what extent remote sensing data can provide an accurate assessment of these changes. Therefore, a new framework is implemented in this work for predicting the underground water level using remote sensing images. Generally, the water level is defined into five levels: Critical, Overexploited, Safe, Saline, and Semi-critical, based on water quantity. In this manuscript, the remote sensing images were acquired from remote sensing images. At first, Wiener filtering was employed for preprocessing. Secondly, the Vegetation Indexes (VI) (Normalized Difference Vegetation Index (NDVI), Normalized Difference Snow Index (NDSI), Infrared index (IRI), Radar Vegetation Index (RVI)), and statistical features (entropy, Root Mean Square (RMS), Skewness, and Kurtosis) were extracted from the preprocessed remote sensing images. Then, the extracted features were combined as a novel hydro index, which was fed to the Ensemble Classifier (EC): Neural Networks (NN), Support Vector Machine (SVM), and improved Deep Convolutional Neural Network (DCNN) models for underground water level prediction in the remote sensing images. The obtained results prove the efficacy of the proposed framework by using different performance measures. The results shows that the False Positive Rate (FPR) of the proposed EC model is 0.0083, which is better than that of existing methods. On the other hand, the proposed EC model has a high accuracy of 0.90, which is superior to the existing traditional models: Long Short-Term Memory (LSTM) network, Naïve Bayes (NB), Random Forest (RF), Recurrent Neural Network (RNN), and Bidirectional Gated Recurrent Unit (Bi-GRU).
Understanding Fuel Saving and Clean Fuel Strategies Towards Green Maritime
- Van Nhanh Nguyen
- Krzysztof Rudzki
- Marek Dzida
- Nguyen Dang Khoa Pham
- Minh Tuan Pham
- Phuoc Quy Phong Nguyen
- Phuong Nguyen Xuan
2023 Pełny tekst Polish Maritime Research
Due to recent emission-associated regulations imposed on marine fuel, ship owners have been forced to seek alternate fuels, in order to meet the new limits. The aim of achieving low-carbon shipping by the year 2050, has meant that alternative marine fuels, as well as various technological and operational initiatives, need to be taken into account. This article evaluates and examines recent clean fuels and novel clean technologies for vessels. The alternative fuels are classified as low-carbon fuels, carbon-free fuels, and carbon neutral fuels, based on their properties. Fuel properties, the status of technological development, and existing challenges are also summarised in this paper. Furthermore, researchers have also investigated energy-saving devices and discovered that zero-carbon and virtually zero-carbon clean fuels, together with clean production, might play an important part in shipping, despite the commercial impracticability of existing costs and infrastructure. More interestingly, the transition to marine fuel is known to be a lengthy process; thus, early consensus-building, as well as action-adoption, in the maritime community is critical for meeting the expectations and aims of sustainable marine transportation
Understanding Sustainable Knowledge-Sharing in Agile Projects: Utilizing Follow-the-Sun Technique (FTS) in Virtual Teams
- Edward Szczerbicki
- Rodrigo Oliveira de Castro
- Cesar Sanin
2023 Pełny tekst
In Agile IT projects, promoting effective knowledge sharing is essential not only for achieving success but also for supporting Sustainable Development Goals (SDGs). However, Companies using virtual teams may face challenges in coordinating work, particularly when teams are distributed across different time zones, ultimately hindering their ability to consistently share knowledge. This can lead to delays and inefficiencies, ultimately impacting the project outcomes and the organization's profitability. To ensure sustainable knowledge sharing, a comprehensive framework is necessary that addresses the environmental, social, economic, and political aspects of the project. This paper proposes a framework that combines the Follow-the-Sun (FTS) technique and the Sustainable Knowledge Sharing Model, enabling 24-hour knowledge sharing in virtual teams and benefiting IT agile projects.
Understanding the kinetics and atmospheric degradation mechanism of chlorotrifluoroethylene (CF2=CFCl) initiated by OH radicals
- Saber Safari Balsini
- Abolfazl Shiroudi
- Farhad Hatamjafari
- Ehsan Zahedi
- Khalil Pourshamsian
- Ahmad Reza Oliaey
2023 PHYSICAL CHEMISTRY CHEMICAL PHYSICS
The atmospheric degradation of chlorotrifluoroethylene (CTFE) by OH˙ was investigated using density functional theory (DFT). The potential energy surfaces were also defined in terms of single-point energies derived from the linked cluster CCSD(T) theory. With an energy barrier of −2.62 to −0.99 kcal mol−1 using the M06-2x method, the negative temperature dependence was determined. The OH˙ attack on Cα and Cβ atoms (labeled pathways R1 and R2, respectively) shows that reaction R2 is 4.22 and 4.42 kcal mol−1, respectively, more exothermic and exergonic than reaction R1. The main pathway should be the addition of OH˙ to the β-carbon, resulting in ˙CClF–CF2OH species. At 298 K, the calculated rate constant was 9.87 × 10−13 cm3 molecule−1 s−1. The TST and RRKM calculations of rate constants and branching ratios were performed at P = 1 bar and in the fall-off pressure regime over the temperature range of 250–400 K. The formation of HF and ˙CClF–CFO species via the 1,2-HF loss process is the most predominant pathway both kinetically and thermodynamically. With increasing temperature and decreasing pressure, the regioselectivity of unimolecular processes of energized adducts [CTFE–OH]˙ gradually decreases. Pressures greater than 10−4 bar are often adequate for assuring saturation of the estimated unimolecular rates when compared to the RRKM rates (in high-pressure limit). Subsequent reactions involve the addition of O2 to the [CTFE–OH]˙ adducts at the α-position of the OH group. The [CTFE–OH–O2]˙ peroxy radical primarily reacts with NO and then directly decomposes into NO2 and oxy radicals. “Carbonic chloride fluoride”, “carbonyl fluoride”, and “2,2-difluoro-2-hydroxyacetyl fluoride” are predicted to be stable products in an oxidative atmosphere.