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  • Ekspertyza naukowo-techniczna dotycząca analizy i oceny rozwiązań projektowych oraz aspektów wykonawczych posadowienia na kolumnach przemieszczeniowych FDC budynku usługowo-apartamentowego przy ul. Bulwar Gdański 9 w Szczecinie
    • Adam Krasiński
    • Andrzej Słabek
    2023

    Ustalenie przyczyn projektowych i wykonawczych wadliwej jakości kolumn fundamentowych do posadowienia budynku biurowo-mieszkalnego

  • Ekspertyza polegająca na wykonaniu analiz space syntax dla oddziału Onkologii w szpitalu w Gliwicach.
    • Weronika Dettlaff
    2023

    Ekspertyza dotyczy wykorzystania analizy syntaktycznej przestrzeni (space syntax analysis) w procesie planowania przestrzeni. Metoda ta pozwala prognozować wpływ konfiguracji przestrzennej na zachowanie użytkowników. Jest przydatna na każdym etapie planowania, zarówno w przypadku przestrzeni miejskich, jak i w budynkach. Miary syntaktyczne opisujące konfigurację przestrzenną umożliwiają opisanie i wyjaśnienie relacji przestrzennych oraz przewidywanie skutków decyzji projektowych. Mimo że metoda ta cieszy się dużą popularnością wśród zagranicznych urbanistów, socjologów, planistów, projektantów wnętrz i informatyków, w Polsce jest jeszcze mało znana i nie jest powszechnie stosowana. Dokument zawiera omówienie genezy analizy syntaktycznej przestrzeni, wyjaśnienie podstawowych pojęć z nią związanych oraz analizę przypadku jej stosowania w procesie planowania poprawy znajdowania drogi (wayfindingu) oraz poruszania się w Narodowym Instytucie Onkologii w Gliwicach.

  • Ekspertyza techniczna dotycząca przyczyn zawilgocenia ścian Katedry w Kwidzynie oraz wpływu zabudowy dwóch kwartałów mieszkalno-usługowych przy Katedrze realizowanych w latach 2010-2011 oraz 2018-2020 na stan zawilgocenia murów Katedry
    • Adam Krasiński
    • Michał Nitka
    • Andrzej Słabek
    2023

    Przedmiotem opracowania jest ekspertyza dotycząca przyczyn zawilgocenia ścian Katedry pw. św. Jana Ewangelisty w Kwidzynie oraz wpływu zabudowy dwóch kwartałów mieszkalno-usługowych przy katedrze, zrealizowanych w latach 2010-2011 oraz 2018-2020 na stan zawilgocenia murów budynku katedry. Ekspertyza swoim zakresem obejmuje ocenę zawilgocenia murów oraz ścian na zewnątrz oraz wewnątrz katedry, jak również wskazuje potencjalne przyczyny oraz czynniki wpływające na taki stan rzeczy np. zmiana stosunków wodnych po zrealizowaniu zabudowy części obszaru Starego Miasta. W ekspertyzie przedstawiono także zalecenia mające na celu wyeliminowanie lub znaczne ograniczenie gromadzenia się wody bezpośrednio przy fundamentach oraz jej wnikania w mury katedry. Opracowanie wykonano na podstawie analiz dostępnych dokumentacji oraz opracowań tj. głównie wcześniejszych ekspertyz, przekazanych przez Zamawiającego. Ponadto podczas odbytych dwóch wizji lokalnych przeprowadzono oględziny oraz nieinwazyjne pomiary wilgotnościowe murów katedry, jak również dokonano wierceń podłoża gruntowego w pobliżu katedry oraz pomiarów geodezyjnych części terenu wokół celem określenia spadów terenu i kierunków spływu wód opadowych.

  • Eksperymentalna analiza wpływu ruchu posuwisto-zwrotnego i obrotowego oraz miejscowych zmian geometrii na skuteczność wypierania cieczy wiertniczych z przestrzeni pierścieniowej
    • Paweł Szewczuk
    2023 Pełny tekst

    Rozprawa przedstawia analizę wpływu ruchu kolumny rur stosowanego w wiertnictwie oraz miejscowych zmian geometrii przestrzeni pierścieniowej na skuteczność procesu wypierania się cieczy. Jest to pierwsze badanie w otwartej literaturze omawiające te czynniki, w którym opisano wyniki eksperymentów na dedykowanym stanowisku badawczym. W pracy omówiony został wpływ węglowodorów na współczesną cywilizację, jak również wpływ skuteczności procesu wypierania cieczy wiertnicznych na powodzenie całej operacji ich pozyskiwania. W dalszej części omówione zostały kroki milowe w zrozumieniu procesu wypierania się cieczy wiertniczych jak i podstawowe zależności matematyczne definiujące ruch cząsteczek płynu. W rozdziale 3 postawione zostały cztery tezy nawiązujące do tematu rozprawy, które w rozdziale 4 zostały potwierdzone opisanymi wynikami eksperymentalnymi. Udowodniono: - zwiększenie wydajności wypierania cieczy z przestrzeni pierścieniowej przy implementacji ruchu posuwisto-zwrotnego; - zwiększenie wydajności procesu przy implementacji ruchu obrotowego; - dalsze zwiększenie wydajności procesu przy implementacji ruchu posuwisto-zwrotnego i obrotowego; - zmniejszenie wydajności procesu w sąsiedztwie zwężeń otworu. Dodatkowo, negatywny wpływ zwężeń został potwierdzony analizą wyników płytkich otworów eksperymentalnych jak i otworów komercyjnych przedstawioną w rozdziale 5.

  • Elastic scattering of electrons by water: An ab initio study
    • Francesca Triggiani
    • Tommaso Morresi
    • Simone Taioli
    • Stefano Simonucci
    2023 Pełny tekst Frontiers in Materials

    In this work we devise a theoretical and computational method to compute the elastic scattering of electrons from a non-spherical potential, such as in the case of molecules and molecular aggregates. Its main feature is represented by the ability of calculating accurate wave functions for continuum states of polycentric systems via the solution of the Lippmann-Schwinger equation, including both the correlation effects and multi-scattering interference terms, typically neglected in widely used approaches, such as the Mott theory. Within this framework, we calculate the purely elastic scattering matrix elements. As a test case, we apply our scheme to the modelling of electron-water elastic scattering. The Dirac-Hartree-Fock self-consistent field method is used to determine the non-spherical molecular potential projected on a functional space spanned by Gaussian basis set. By adding a number of multi-centric radially-arranged s-type Gaussian functions, whose exponents are system-dependent and optimized to reproduce the properties of the continuum electron wave function in different energy regions, we are able to achieve unprecedented access to the description of the low energy range of the spectrum (0.001 < E < 10 eV) up to keV, finding a good agreement with experimental data and previous theoretical results. To show the potential of our approach, we also compute the total elastic scattering cross section of electrons impinging on clusters of water molecules and zundel cation. Our method can be extended to deal with inelastic scattering events and heavy-charged particles.

  • Electrically Conductive Carbon‐based (Bio)‐nanomaterials for Cardiac Tissue Engineering
    • Negin Jalilinejad
    • Mohammad Rabiee
    • Nafiseh Baheiraei
    • Ramin Ghahremanzadeh
    • Reza Salarian
    • Navid Rabiee
    • Omid Akhavan
    • Payam Zarrintaj
    • Aleksander Hejna
    • Mohammad Saeb
    • Ali Zarrabi
    • Esmaeel Sharifi
    • Sattar Yousefiasl
    • Ehsan Nazarzadeh Zare
    2023 Pełny tekst Bioengineering & Translational Medicine

    A proper self-regenerating capability is lacking in human cardiac tissue which along with the alarming rate of deaths associated with cardiovascular disorders makes tissue engineering critical. Novel approaches are now being investigated in order to speedily overcome the challenges in this path. Tissue engineering has been revolutionized by the advent of nanomaterials, and later by the application of carbon-based nanomaterials because of their exceptional variable functionality, conductivity, and mechanical properties. Electrically conductive biomaterials used as cell bearers provide the tissue with an appropriate microenvironment for the specific seeded cells as substrates for the sake of protecting cells in biological media against attacking mechanisms. Nevertheless, their advantages and shortcoming in view of cellular behavior, toxicity, and targeted delivery depend on the tissue in which they are implanted or being used as a scaffold. This review seeks to address, summarize, classify, conceptualize, and discuss the use of carbon-based nanoparticles in cardiac tissue engineering emphasizing their conductivity. We considered electrical conductivity as a key affecting the regeneration of cells. Correspondingly, we reviewed conductive polymers used in tissue engineering and specifically in cardiac repair as key biomaterials with high efficiency. We comprehensively classified and discussed the advantages of using conductive biomaterials in cardiac tissue engineering. An overall review of the open literature on electroactive substrates including carbon-based biomaterials over the last decade was provided, tabulated, and thoroughly discussed. The most commonly used conductive substrates comprising graphene, graphene oxide, carbon nanotubes, and carbon nanofibers in cardiac repair were studied.

  • Electrochemical Production of Sodium Hypochlorite from Salty Wastewater Using a Flow-by Porous Graphite Electrode
    • Ahmed A. Afify
    • Gamal K. Hassan
    • Hussein Al-Hazmi
    • Rozan M. Kamal
    • Rehab M. Mohamed
    • Jakub Drewnowski
    • Joanna Majtacz
    • Jacek Mąkinia
    • Heba A. El-Gawad
    2023 Pełny tekst ENERGIES

    The production of sodium hypochlorite (NaOCl) from salty wastewater using an electrochemical cell has several advantages over other methods that often require hazardous chemicals and generate toxic waste, being more sustainable and environmentally friendly. However, the process of producing sodium hypochlorite using an electrochemical cell requires careful control of the operating conditions, such as the current density, flow rate, inert electrode spacing, and electrolyte concentration, to optimize the conversion efficiency and prevent electrode fouling and degradation. In this study, NaOCl was produced via a bench-scale electrochemical cell using a flowing porous graphite electrode in a continuous flow system from salty wastewater collected from the Suez Canal in Egypt. The aim of the investigation was to examine the factors that affect the concentration of NaOCl and energy consumption, such as anodic current density, salinity, inert electrode spacing, and influent feed flow rate. A lab-scale reactor with two electrodes was used to conduct the experiments. The highest NaOCl yield of 20.6% was achieved with a graphite electrode, which had high current efficiency and rigidity at a flow rate of 4.5 mL/min, a current density of 3.183 mA/cm2, an electrode space of 0.5 cm, salinity of 40,000 ppm, and a pH of 6.4. The power consumption under these conditions was 0.0137 kwh. Additionally, a statistical and least square multivariate regression technique was employed to establish a correlation for predicting the % NaOCl production. The obtained correlation had an R2 value of 98.4%. Overall, this investigation provides valuable insights into the production of NaOCl using a continuous flow system from salty wastewater, which could have potential for industrial applications in various sectors such as textiles, detergents, paper, and pulp.

  • Electrochemistry/mass spectrometry (EC/MS) for fast generation and identification of novel reactive metabolites of two unsymmetrical bisacridines with anticancer activity.
    • Agnieszka Potęga
    • Valentin Göldner
    • Erik Niehaves
    • Ewa Paluszkiewicz
    • Uwe Karst
    2023 JOURNAL OF PHARMACEUTICAL AND BIOMEDICAL ANALYSIS

    The development of a new drug requires knowledge about its metabolic fate in a living organism, regarding the comprehensive assessment of both drug therapeutic activity and toxicity profiles. Electrochemistry (EC) coupled with mass spectrometry (MS) is an efficient tool for predicting the phase I metabolism of redox-sensitive drugs. In particular, EC/MS represents a clear advantage for the generation of reactive drug transformation products and their direct identification compared to biological matrices. In this work, we focused on the characterization of novel electrochemical products of two representative unsymmetrical bisacridines (C-2028 and C-2045) with demonstrated high anticancer activity. The electrochemical thin-layer flow-through cell μ-PrepCell 2.0 (Antec Scientific) was used here for the effective metabolite electrosynthesis. The electrochemical simulation of C-2028 reductive and C-2045 oxidative metabolism resulted in the generation of new products that were not observed before. The formation of nitroso [M-O+H]+ and azoxy [2M-3O+H]+ species from C-2028, as well as a series of hydroxylated and/or dehydrogenated products, including possible quinones [M-2H+H]+ and [M+O-2H+H]+ from C-2045, was demonstrated. For the latter, a glutathione S-conjugate (m/z 935.3130) was also obtained in measurements supplemented with the excess of reduced glutathione. For the identification of the products of interest, structural confirmation based on MS/MS fragmentation experiments was performed. Novel products of electrochemical conversions of unsymmetrical bisacridines were discussed in the context of their possible biological effect on the human organism.

  • Electron Scattering from Methyl Formate (HCOOCH3): A Joint Theoretical and Experimental Study
    • Natalia Tańska
    • Edvaldo Bandeira
    • Alessandra Souza Barbosa
    • Kuba Wójcik
    • Sylwia Dylnicka
    • Elżbieta Ptasińska-Denga
    • Czesław Szmytkowski
    • Márcio H F Bettega
    • Paweł Możejko
    2023 Pełny tekst JOURNAL OF PHYSICAL CHEMISTRY A

    Elastic low-energy electron collisions with methyl formate have been studied theoretically at the level of various theories. The elastic integral cross section was calculated using Schwinger multichannel and R-matrix methods, in the static-exchange and static-exchange plus polarization levels of approximations for energies up to 15 eV. The absolute total cross section for electron scattering from methyl formate has been measured in a wide energy range (0.2−300 eV) using a 127° electron spectrometer working in the linear transmission configuration. The integral elastic and the absolute total cross sections display a π* shape resonance at around 1.70−1.84 eV, which can be related to the resonance visible for formic acid, and a broad structure located at 7−8 eV, which can be associated to a superposition of σ* shape resonances. Our results were compared with theoretical and experimental results available in the literature and with the results of electron collisions with formic acid. The additivity rule was used to estimate the total cross section of methyl formate and the results agree well with the experimental data.

  • Electronic structure of intertwined kagome, honeycomb, and triangular sublattices of the intermetallics MCo2Al9 ( M = Sr, Ba)
    • Chiara Bigi
    • Sahar Pakdel
    • Michał Winiarski
    • Pasquale Orgiani
    • Ivana Vobornik
    • Jun Fujii
    • Giorgio Rossi
    • Vincent Polewczyk
    • Phil D. C. King
    • Giancarlo Panaccione
    • Tomasz Klimczuk
    • Kristian Sommer Thygesen
    • Federico Mazzola
    2023 Pełny tekst PHYSICAL REVIEW B

    Intermetallics are an important playground to stabilize a large variety of physical phenomena, arising from their complex crystal structure. The ease of their chemical tunabilty makes them suitable platforms to realize targeted electronic properties starting from the symmetries hidden in their unit cell. Here, we investigate the family of the recently discovered intermetallics MCo2Al9 (M=Sr, Ba) and we unveil their electronic structure. By using angle-resolved photoelectron spectroscopy and density functional theory calculations, we discover the existence of Dirac-like dispersions as ubiquitous features in this family, coming from the hidden kagome and honeycomb symmetries embedded in the unit cell. Finally, from calculations, we expect that the spin-orbit coupling is responsible for opening energy gaps in the electronic structure spectrum, which also affects the majority of the observed Dirac-like states. Our study constitutes an experimental observation of the electronic structure of MCo2Al9 and proposes these systems as hosts of Dirac-like physics with intrinsic spin-orbit coupling. The latter effect suggests MCo2Al9 as a future platform for investigating the emergence of nontrivial topology.

  • Electron-Induced Decomposition of 5-Bromo-4-thiouracil and 5-Bromo-4-thio-2′-deoxyuridine: The Effect of the Deoxyribose Moiety on Dissociative Electron Attachment
    • Farhad Izadi
    • Adrian Szczyrba
    • Magdalena Datta
    • Olga Ciupak
    • Sebastian Demkowicz
    • Janusz Rak
    • Stephan Denifl
    2023 Pełny tekst INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES

    When modified uridine derivatives are incorporated into DNA, radical species may form that cause DNA damage. This category of molecules has been proposed as radiosensitizers and is currently being researched. Here, we study electron attachment to 5-bromo-4-thiouracil (BrSU), a uracil derivative, and 5-bromo-4-thio-20 -deoxyuridine (BrSdU), with an attached deoxyribose moiety via the N-glycosidic (N1-C) bond. Quadrupole mass spectrometry was used to detect the anionic products of dissociative electron attachment (DEA), and the experimental results were supported by quantum chemical calculations performed at the M062X/aug-cc-pVTZ level of theory. Experimentally, we found that BrSU predominantly captures low-energy electrons with kinetic energies near 0 eV, though the abundance of bromine anions was rather low compared to a similar experiment with bromouracil. We suggest that, for this reaction channel, proton-transfer reactions in the transient negative ions limit the release of bromine anions.

  • Electro-optical transducer based on indium-tin-oxide-coated optical fiber for analysis of ionized media
    • Petr Sezemsky
    • Marcin Koba
    • Pavel Curda
    • Robert Bogdanowicz
    • Vitezslav Stranak
    • Mateusz Śmietana
    2023 MEASUREMENT

    The paper introduces a concept of an optical fiber based electro-optical transducer for monitoring of ionized media, such as low-temperature plasma. It utilizes optical fiber with a section of a core coated with tailored indium tin oxide (ITO) thin film and thus combines the optical phenomena of lossy-mode resonance (LMR) with the electrostatic probe. ITO is an optically transparent and electrically conductive material and if its properties such as thickness, as well as optical and electrical properties are optimized, the ITO-LMR sensor is sensitive to changes in properties of both the film and its close vicinity. The ITO-LMR sensor, with its conductive surface, corresponds well by shape and geometry to electrostatic Langmuir probe. In this work, ITO-LMR sensor was employed for simultaneous optical (LMR spectrum) and electrical (current–voltage) interrogation of ionized media, where low-temperature plasma was used as an example. It has been found that optical and electrical responses highly correspond to one another and are attributed to changes in the properties of a plasma sheath surrounding the sensor. The charged species in the sheath influence not only its electrical and optical properties, but also optical properties of ITO. Thus, the sensor allows for real-time, optical monitoring of properties of the ionized media and obtaining optical readout that can be delivered directly to distant locations via an optical fiber without interference of electromagnetic noise.

  • Electrophoretically deposited titanium and its alloys in biomedical engineering: Recent progress and remaining challenges
    • Balbina Makurat-Kasprolewicz
    • Agnieszka Ossowska
    2023 Pełny tekst JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART B-APPLIED BIOMATERIALS

    Over the past decade, titanium implants have gained popularity as the number of performed implantation operations has significantly increased. There are a number of methods for modifying the surface of biomaterials, which are aimed at extending the life of titanium implants. The developments in this field in recent years have required a comprehensive discussion of all the properties of electrophoretically deposited coatings on titanium and its alloys, taking into account their bioactivity. The development that took place in this field in recent years required a comprehensive discussion of all the properties of coatings electrophoretically deposited on titanium and its alloys, with particular emphasis on their bioactivity. Herein, we attempt to assess the influence of the electrophoretic deposition (EPD) process parameters on these coatings' biological and mechanical properties. Particular attention has been addressed to the in-vitro and in-vivo studies conducted hitherto. We have seen an increased interest in using titanium alloys without the addition of toxic compounds and gaps in the EPD field such as the uncommon endeavors to develop a “Design of experiments” approach as well as the lack of assessment of the surface free energy and detailed topography of electrophoretically deposited coatings. The exact correlation of coating properties with EPD process parameters still seems explicitly not understood, necessitating more future investigations. Ipso facto, the exact mechanism of particle agglomeration and Hamaker's law need to be fathomable.

  • Ellipticity in couple-stress elasticity
    • Victor Eremeev
    • Daria Scerrato
    • Violetta Konopińska-Zmysłowska
    2023 Pełny tekst ZEITSCHRIFT FUR ANGEWANDTE MATHEMATIK UND PHYSIK

    We discuss ellipticity property within the linear couple-stress elasticity. In this theory, there exists a deformation energy density introduced as a function of strains and gradient of macrorotations, where the latter are expressed through displacements. So the couple-stress theory could be treated as a particular class of strain gradient elasticity. Within the micropolar elasticity, the model is called Cosserat pseudocontinuum or medium with constrained rotations. Applying the classic definitions of ordinary ellipticity and strong ellipticity to static equations of the couple-stress theory, we conclude that these equations are neither elliptic nor strongly elliptic. As a result, one should be aware of extending properties of full strain gradient models such as Toupin–Mindlin strain gradient elasticity to models with incomplete set of second derivatives.

  • Ellipticity of gradient poroelasticity
    • Victor Eremeev
    2023 INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE

    We discuss the ellipticity properties of an enhanced model of poroelastic continua called dilatational strain gradient elasticity. Within the theory there exists a deformation energy density given as a function of strains and gradient of dilatation. We show that the equilibrium equations are elliptic in the sense of Douglis–Nirenberg. These conditions are more general than the ordinary and strong ellipticity but keep almost all necessary properties of equilibrium equations. In particular, the loss of the ellipticity could be considered as a criterion of a strain localization or material instability.

  • Elucidation of chemical compounds in different extracts of two Lavandula taxa and their biological potentials: Walking with versatile agents on the road from nature to functional applications
    • Gokhan Zengin
    • Sakina Yagi
    • Selami Selvi
    • Zoltán Cziáky
    • József Jeko
    • Kouadio Ibrahime Sinan
    • Asena Ayyüce Topcu
    • Fatih Erci
    • Grzegorz Boczkaj
    2023 INDUSTRIAL CROPS AND PRODUCTS

    Due to their health-promoting and nutraceutical properties, lavenders are frequently employed in the food and pharmaceutical industries. Here, we focused on investigate the chemical profile of hexane, MeOH, and water extracts of leaf, flower, and root of L. pedunculata and L. stoechas and to assess their antioxidant, enzyme inhibitory, and antibacterial properties. The highest total polyphenolic and flavonoids contents were recorded from the water and MeOH extracts of the leaf and flower of L. stoechas, respectively. Our HPLC/MS/MS analysis detected over 90 secondary metabolites, consisting of both known and novel terpenoids, polyphenols, flavonoids, and their derivative. Water leaf extract of L. stoechas displayed significantly (p < 0.05) the highest antiradical, Cu2+ and Fe3+ reducing capacity while hexane extract of the leaf and MeOH extract of the flower of L. pedunculata revealed the best metal chelating ability and total antioxidant activity respectively. The hexane extract of the leaf of L. pedunculata exerted the highest acetylcholinesterase and tyrosinase inhibition activity, whereas the hexane extracts from L. stoechas leaf and L. pedunculata root recorded the highest ability to inhibit the butyrylcholinesterase and ⍺-amylase enzymes respectively. The water extracts of the leaf of the two species, besides the hexane extract of the leaf of L. pedunculata exerted the best inhibition effect against the α-glucosidase. The sensitivities of Gram-positive and Gram-negative bacteria species against different extracts at two different concentrations were tested based on agar well diffusion assay. According to the result, we found that the n-hexane extract of L. stoechas-flowers showed the highest antibacterial activity. In conclusion, the results suggest that both Lavandula species have promising potential as sources of bioactive agents for various industrial applications.

  • Emerging Processes for Sustainable Processing of Food Ingredients and Products
    • Roberto Castro Munoz
    2023 Pełny tekst Foods

    In recent decades, traditional food processing processes, such as homogenization, pasteurization, canning, drying, and smoking, among others, have been successfully applied to obtain, to some extent, acceptable food items. However, with the increasing food demand, as a consequence of the growing population worldwide, new, tunable, and enriched food products are demanded, requiring the implementation of emerging technologies in different areas of food processing. Such technologies offer the possibility of tuning the properties of food ingredients and several products and byproducts from traditional transformation processes [1,2]. Additionally, innovative technologies are providing relevant insights regarding reducing their waste, representing a promising alternative to environmental issues as well [3]. Therefore, we point out the importance of innovative and emerging techniques for processing food ingredients, products, and new food formulations.

  • Emotions and Their Relation with Knowledge Risks in Organizations
    • Małgorzata Zięba
    2023

    The aim of this chapter is to analyze and present knowledge risks from the perspective of emotions. Every year, new studies are published, where novel aspects of knowledge management field are examined and tested. One of such aspects that is worth examination and exploration is the role of emotions (both positive and negative) experienced by employees and managers that can contribute to their behaviors concerning knowledge risks (e.g., knowledge hiding, knowledge loss) and, therefore, knowledge management in organizations. Examples of positive emotions are love, joy, satisfaction, contentment, interest, amusement, happiness, serenity, or awe, while the most commonly felt negative emotions are fear, anger, disgust, sadness, rage, loneliness, melancholy, and annoyance. In this chapter, the potential influence of those emotions on the behaviors related to knowledge risks will be examined. The chapter lays theoretical grounds for the future studies related to emotions and their role in knowledge risks behaviors manifested by employees and managers.

  • Empirical analysis of tree-based classification models for customer churn prediction
    • Fatima E. Usman-Hamza
    • Abdullateef O. Balogun
    • Salahdeen K. Nasiru
    • Luiz Fernando Capretz
    • Hammed Mojeed
    • Shakirat A. Salihu
    • Abimbola G. Akintola
    • Modinat Abolore Mabayoje
    • Joseph B. Awotunde
    2023 Pełny tekst Scientific African

    Customer churn is a vital and reoccurring problem facing most business industries, particularly the telecommunications industry. Considering the fierce competition among telecommunications firms and the high expenses of attracting and gaining new subscribers, keeping existing loyal subscribers becomes crucial. Early prediction of disgruntled subscribers can assist telecommunications firms in identifying the reasons for churn and in deploying applicable innovative policies to boost productivity, maintain market competitiveness, and reduce monetary damages. Controlling customer churn through the development of efficient and dependable customer churn prediction (CCP) solutions is imperative to attaining this goal. According to the outcomes of current CCP research, several strategies, including rule-based and machine-learning (ML) processes, have been proposed to handle the CCP phenomenon. However, the lack of flexibility and robustness of rule based CCP solutions is a fundamental shortcoming, and the lopsided distribution of churn datasets is deleterious to the efficacy of most traditional ML techniques in CCP. Regardless, ML-based CCP solutions have been reported to be more effective than other forms of CCP solutions. Unlike linear-based, instance-based, and function-based ML classifiers, tree-based ML classifiers are known to generate predictive models with high accuracy, high stability, and ease of interpretation. However, the deployment of tree-based classifiers for CCP is limited in most cases to the decision tree (DT) and random forest (RF). Hence, this research investigated the effectiveness of tree-based classifiers with diverse computational properties in CCP. Specifically, the CCP performances of diverse tree-based classifiers such as the single, ensemble, enhanced, and hybrid tree-based classifiers are investigated. Also, the effects of data quality problems such as the class imbalance problem (CIP) on the predictive performances of tree-based classifiers and their homogeneous ensemble variants on CCP were assessed. From the experimental results, it was observed that the investigated tree-based classifiers outperformed other forms of classifiers such as linear-based (Support Vector Machine (SVM)), instance-based (K-Nearest Neighbour (KNN)), Bayesian-based (Naïve Bayes (NB)) and function-based (MultiLayer Perceptron (MLP)) classifiers in most cases with or without the CIP.

  • Empirical Relationship Describing Total Convective and Radiative Heat Loss in Buildings
    • Michał Ryms
    • Grzegorz J. Kwiatkowski
    • Witold Lewandowski
    2023 Pełny tekst International Journal of Heat and Technology

    On the basis of theoretical considerations of convective-radiative heat transfer, a relationship was developed enabling the total convective and radiative heat flux QC+R emitted from any object at tw and its surroundings at t∞ to be calculated from known values of the surface temperature of such an object, i.e., the known temperature difference Δt=tw - t∞ and average air temperature Tav. This relationship is applied to thermal imaging cameras with the aim of developing appropriate software to enhance their measurement capabilities. They can then be used not only for monitoring and measuring temperature, local overheating, heat losses through insulation materials, thermal bridges, constructional defects, moisture, etc., but also for measuring the heat losses from any object, such walls and buildings. This empirical relationship includes constants relating to the object itself, such as its characteristic dimension l, surface area A, emissivity ε and temperature parameters, which depend on tw, t∞, Δt and Tav and on the physical properties of air. Experimental validation of the proposed relationship, performed for two values of the surface emissivity ε, showing the discrepancies ΔQC+R=1.75% (for ε=0.884) and 4.85% (for ε=0.932), has confirmed its correctness and its practicability.