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  • Bridge Ergonomic Design: A Review
    • Michał Stopa
    • Rafał Szłapczyński
    2022 Pełny tekst TransNav - The International Journal on Marine Navigation and Safety of Sea Transportation

    Human error remains the most common cause of marine incidents and it is worth emphasizing that navigator’s performance is directly affected by ergonomic factors on the bridge. Studies regarding influence of bridge design and work environment on the operator are rare, thus the main purpose of this paper is to fill in this gap. Documents issued by recognized organizations, research publications and additional sources were reviewed to check if navigators obtain enough support in this area and what should be improved. It was found that present ergonomic guidelines for the bridge design require revision and there is a need for making the regulations more meaningful and direct. The main documents that require reworking include Guidelines on Ergonomics Criteria for Bridge Equipment and Layout, International Convention of Standards of Training, Certification and Watchkeeping (STCW) as well as selected parts of SOLAS V/15 regulation.

  • Bridge Non-Destructive Measurements Using a Laser Scanning during Acceptance Testing: Case Study
    • Paweł Tysiąc
    • Mikołaj Miśkiewicz
    • Dawid Bruski
    2022 Pełny tekst Materials

    Owing to the recent proliferation of inventory works on roads and railways, bridge acceptance tests have increased exponentially. These tests’ results are often misinterpreted owing to the use of various measuring equipment types, rendering integrated interpretation problematic. It is also problematic that adjusting the measurement method is difficult when the structure’s response to load is uncertain. Therefore, it is important to observe the largest possible range of possible deformations. For this reason, the present study suggests a novel approach to bridge non-destructive measurements using a laser scanner during acceptance testing. The main advantage of our method is the ability it affords to observe all points of the structure during testing, an ability that is extremely important is the absence of unambiguous data regarding the bridge’s condition. To significantly increase the scanning accuracy (up to 0.5 mm), measurements from a limited number of linear sensors are used (whose accuracy is up to 0.1 mm). To achieve optimal accuracy, we performed the following steps: first, we adapted the precision requirements to the numerical project. For this purpose, we used potentiometric sensors to measure linear deformations. Next, we performed laser scanning measurements from two scan positions. Finally, we filtered the data for the selected cross-section and modelled the points into polynomial deflection. The performed tests confirmed that the structure’s response was as predicted by the FEM model, and the object was approved for use. Our future tests will be based on the selection of a structure with minimal measurement errors, and the results will be compared using a total station, ensuring the highest possible quality of service, which can be repeated in simple steps. As study objects, we presented two items: the first without proper calibration on a linear sensor and the second using linear sensors to present the highest possible accuracy of our experiment.

  • Broadening the scope of measurement and analysis of vibrations of an organ pipe employing intensity probe, simulations, and highspeed camera
    • Paolo Bordoni
    • Józef Kotus
    • Piotr Odya
    • Fabio Antonacci
    • Bożena Kostek
    2022 Journal of the Acoustical Society of America

    This paper shows an integrated approach to measure, analyze, and model phenomena occurring in an organ pipe driven by pressurized air. The aim of this paper is two-fold, i.e., to measure the pressure signal and the intensity field around the mouth by means of an intensity probe and to visualize and observe the motion of the air jet, which represents the excitation mechanism of the system. This is realized through two techniques, i.e., measurements conducted on a Bourdon organ pipe and numerical simulations of the air flow in a pipe of the same geometry. Measurements were carried out in an anechoic chamber using the Cartesian robot. Simulations were performed on a server equipped with graphical cards, and the results were visualized employing ParaVIEW software. Moreover, an analysis was conducted by observing phenomena in both audio and video signals. A high-speed camera was employed to make the jet getting out from the windway visible. This was realized using the steam that produced the reaction of dry ice and hot water. This choice has been adopted to ensure safety conditions in the measurement environment. Finally, a comparison between the sound spectrum measured and the spectrum resulted from simulations was made.

  • Budowa portu w Gdyni 1920-1939: "ksztatł rozwartych palców ręki, władczo wyciągniętej ku morzu"
    • Maria Sołtysik
    2022

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  • Building modernization located in the conservation protection zone in the aspect of technical conditions
    • Maciej Niedostatkiewicz
    2022 Pełny tekst Inżynieria Bezpieczeństwa Obiektów Antropogenicznych

    The paper presents a description of the technical condition of the building after many years of operation and analyzes the impact of the current use and the lack of regular periodic repairs on the technical efficiency of the building. The influence of the technical solutions applied during the construction of the building on the current limitations related to the planned, target change in the way of use was discussed. Variant conceptual solutions for the modernization of the building were also presented, taking into account the preservation of its historic character.

  • Bunker demolition located in a conservation protection zone in the light of technical, national defense, functional-utility and economic conditions
    • Maciej Niedostatkiewicz
    • Tomasz Majewski
    2022 Pełny tekst Inżynieria Bezpieczeństwa Obiektów Antropogenicznych

    The paper presents a description of the technical condition of the Bunker building located at the port quay, which has been out of use for several decades. The direct reason for the cessation of exploitation was the deletion of Bunker from the Civil Defense records. The paper contains a detailed analysis of the Bunker's technical condition, also taking into account the national defense, functional and utility aspects and the issues of economics of carrying out renovation works. The paper shows that despite the location of the Bunker in the conservation protection zone, the optimal solution was its demolition and the final use of the area where the Bunker was located as a place for the construction of warehouse buildings with parameters adapted to the current needs and target transshipment capabilities of the port quay.

  • Byłe porty lotnicze jako element dziedzictwa architektonicznego i urbanistycznego
    • Agnieszka Szuta
    2022 Pełny tekst

    Tematyka niniejszej rozprawy dotyczy wpływu byłych, cywilnych portów lotniczych na kształtowanie nowej zabudowy na ich dawnym terenie. Przebadane zostają wartości kulturowe oraz społeczno­ekonomiczne pozostałej po nich infrastruktury. Rozwój i dzieje lotnictwa są przedmiotem zainteresowania historyków, a kwestie związane z budową nowych portów lotniczych - urbanistów, co czyni zagadnienia te przedmiotem licznych badań. Niemniej pozornie bogata literatura tematu ma zasadniczą lukę: brakuje opracowań nt. infrastruktury zniszczonych i/lub pełniących nowe funkcje portów lotniczych. W pozycjach poruszających tematykę wartościowania dziedzictwa techniki obiekty związane z infrastrukturą lotniskową traktowane są marginalnie. Wobec powyższego w dysertacji rozpoznano lotniska funkcjonujące w dawnych i obecnych granicach Polski, które obsługiwały loty pasażerskie do lat 70. XX w. Zostały skatalogowane i scharakteryzowane, a przeprowadzone analizy umożliwiły wyłonienie Portu Lotniczego Gdańsk-Wrzeszcz, którego pozostałości, jako jedyne w kraju, stały się silnym elementem kompozycyjnym zaprojektowanego na jego terenie osiedla mieszkaniowego. Przeprowadzono waloryzację pozostałości po ww. porcie oraz zbadano związki społeczeństwa z tym miejscem. Ponadto zweryfikowano wartości społeczno­ekonomiczne byłych portów lotniczych oraz rozpoznano możliwości ich ponownego wykorzystania. Odwołując się do najnowszych metod waloryzacji dziedzictwa techniki zaproponowano uznanie, dotychczas nieuwzględnionej, wartości potencjału ekologicznego.

  • Can architecture be 11-dimensional? The nature of space in the architecture of the digital world era
    • Mosleh Ahmadi
    • Justyna Martyniuk-Pęczek
    2022 Pełny tekst Space-Society-Economy

    This research aims to explore the development of architectural theories about ‘architectural dimensions’ and look at architecture as a multidimensional space. It is important to understand that with today's development of virtual reality technology and through the combination of theories of physics and architecture, a new possibility of creating space has emerged. The arguments are made through inductive reasoning and grounded theory approach. According to the M-theory (one of the contemporaneous leading physics theories), physics suggests a world with 11 dimensions. A question could be asked in this way that should architecture be perceived whether as subjective or objective? Therefore, the theoretical arguments have been focused on three parameters of ‘Subjectivity’, ‘Time’, and ‘Reality’. These parameters are the joint integration of the theories in architecture and quantum physics about dimensions. This representation is justified by the demonstration of identical theoretical attributes that are manifested both in the continuum of ‘quantum architecture’ and ‘quantum realm’. On this basis, the dimensions counted for the status quo of architecture would be 1. ‘Physical and Virtual Creatress of Space’ (Physical/Virtual depth, edge, and ceiling height) or a space of mixed reality (real world merged with virtual reality); 2. ‘Active Architecture’ (corporation of Relative and External time in the creation of Physical/Virtual Dynamism); and 3. ‘Smart Engagement of Experiential Dimensions’ (interactive mental, sensorial, and corporeal engagements based on local and non-local realities). These three factors account for ‘Reality’, ‘Time’, and ‘Subjectivity’, respectively. In the end, ‘Eleven-Dimensional Architecture’ would be introduced. Examples of this kind of architecture could be found in smart architecture with mixed reality settings.

  • Cannabinoids: Challenges, opportunities and current techniques towards its extraction and purification for edibles
    • Sharon Lustenberger
    • Grzegorz Boczkaj
    • Roberto Castro-Muñoz
    2022 Food Bioscience

    Due to the multiple health benefits associated with the consumption of cannabinoids, there is a current trend on continuing to explore their biological properties. Cannabidiol (CBD) is likely to be the most investigated endocannabinoid from the cannabis plant. Unfortunately, the purification of CBD from its natural source and psychotropic analogue (tetrahydrocannabinol, THC) is timely challenging for the research community based on the similar physiochemical properties of both molecules. This latter fact becomes relevant for the final application of CBD in edibles as a bioactive compound. Therefore, this paper comprehensively reviews the latest development works (over the last 2–3 years) aiming at the extraction of cannabinoids and purification of CBD using traditional, emerging, and synergistic extraction techniques and strategies. Particular emphasis and discussion have been focused on the innovative extraction techniques and the relevant outcomes with detailed strategies to meet such high extraction rates. Biological properties (at lab-scale and clinical case studies), current practices, progress in legislation and commercialization of CBD are also overviewed. Finally, according to the findings of this review, the future trends and research gaps are also given.

  • Capacity Transforming challenges into opportunities
    • Joanna Bach-Głowińska
    • Jacek Łubiński
    • Joanna Tobolewicz
    2022

    The Urban Initiative Laboratory (UIL) aims to upgrade the smart city concept in Gdańsk by introducing the Food-Water-Energy (FWE) nexus to the city. It was agreed in the CRUNCH international consortium that projects on different scales would be implemented in the individual countries to test the Integrated Decision Supportive system platform, which would, in principle, concern urban scale. The regular urban scale was to be researched in Urban Living Labs (ULL) in Uppsala, Eindhoven, Southend-on-Sea, and Taipei. The Miami project developed appropriate tools for an IDSS platform, with maximum use of GIS data on a regional scale. The open test bed of the micro ULL FWE Nexus Square – i.e. a pavilion prototype – was supposed to be opened in Gdańsk in June 2020, in accordance with the CRUNCH action plan. However, the approved functionalities of the pavilion were no longer applicable due to the significant social changes in public spaces caused by the Covid-19 pandemic. Moreover, the ULL’s business partner used the prototype pavilion for the purpose of a mobile diagnostic laboratory in a different location. It was absolutely clear that UIL could not continue the micro ULL in Gdańsk in the form previously planned. ULLs focus on, amongst other things, strategic learning to achieve systemic change (van den Bosch, 2010) and better anticipation of constraints on upscaling and inclusion (Dijk et al., 2019). Therefore, UIL began the theoretical research, which emerged from tackling the impacts of the Covid-19 pandemic on city life from the urban perspective.

  • Capping ligand initiated CuInS2 quantum dots decoration on, ZnIn2S4 microspheres surface under different alkalinity levels resulting in different hydrogen evolution performance
    • Onur Cavdar
    • Anna Malankowska
    • Justyna Łuczak
    • Andrzej Żak
    • Wojciech Lisowski
    • Tomasz Klimczuk
    • Adriana Zaleska-Medynska
    2022 Pełny tekst COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS

    Surface distribution of quantum dots (QDs) at the semiconductor matrix caused by synthesis condition (e.g. pH of solution during coupling) could lead to different photocatalytic activity. Thus, achieving an optimal covering of semiconductor matrix by QDs has been challenging. Herein, the influence of the alkalinity level of aqueous decoration medium for the coupling of mercaptoundecanoic acid (MUA) capped CuInS2 quantum dots (CIS) and ZnIn2S4 microspheres (ZIS) on photocatalytic hydrogen evolution (PHE) performance was investigated. Aqueous decoration medium with different alkalinity levels for the formation of ZIS/CIS photocatalytic system resulted in significantly different PHE performances in the presence of (0.5 wt%) Pt co-catalyst deposition without any change in crystal structure of ZIS matrix up to pH 12.5. The photocatalytic system obtained at pH 10.5 possessed the highest performance followed by the decrease at pH 11.5 and again the remarkable increase was detected at pH 12.5 that was the pH level for uniform dispersion of CIS in aqueous medium. This work remarks the importance of the nanoparticle’s aggregates on PHE performance over non-toxic ZnIn2S4/CuInS2 photocatalytic system.

  • Case Study on the Use of Unmanned Aerial Vehicles for the Maintenance of Ocean Engineering Facilities
    • Mariusz Deja
    • Mirosław Gerigk
    • Mieczysław Siemiątkowski
    2022 Pełny tekst IFAC-PapersOnLine

    The article presents the concept of using innovative unmanned aerial vehicles (UAVs), including autonomous UAV-I for inspection activities, auxiliary and transport works in the processes of servicing large-scale ocean engineering structures in the offshore part of the sea. The proposed areas of application of UAV-I devices and key technologies determining the possibility of using these vehicles in difficult operating conditions at sea are presented. Simulation studies were carried out on the possibility of sequencing maintenance tasks and maintaining the efficiency of technical devices installed in various locations of the mining platform at relatively short time intervals not exceeding 3-4 hours. It was envisaged to use a limited resource of three drones with a specific purpose and functional characteristics. The limitation of the time horizon of the analysis was determined by the specific ranges of drone flights and the time-consuming nature of their operations.

  • Cassier E. Filozofia form symbolicznych tom 3. Fenomenologia poznania.Przekład, wstęp i opracowanie : Przemysław Parszutowicz i Andrzej Karalus.Wydaw. Marek Derewiecki, 2022
    • Andrzej Karalus
    • Przemysław Parszutowicz
    2022

    Trzeci tom opus magnum Cassirera zawiera szczegółową prezentację teoretycznego szkieletu całej koncepcji Filozofii form symbolicznych Cassirera oraz jej głównych pojęć (takich jak symboliczna pregnancja), wraz z opisem funkcji świadomości i poziomów jej obiektywizacji. Naczelnym przedmiotem badań tomu jest ogólnie pojęta świadomość rozumiana jako specyficzna funkcja poznawczo-syntetyzująca, kształtująca różnorodność świata kultury. Dużą partię książki stanowią rozważania na temat „najwyższej” formy obiektywizacji, jaką reprezentują nauki ścisłe.

  • Categorization of emotions in dog behavior based on the deep neural network
    • Zdzisław Kowalczuk
    • Michał Czubenko
    • Weronika Żmuda-Trzebiatowska
    2022 Pełny tekst COMPUTATIONAL INTELLIGENCE

    The aim of this article is to present a neural system based on stock architecture for recognizing emotional behavior in dogs. Our considerations are inspired by the original work of Franzoni et al. on recognizing dog emotions. An appropriate set of photographic data has been compiled taking into account five classes of emotional behavior in dogs of one breed, including joy, anger, licking, yawning, and sleeping. Focusing on a particular breed makes it easier to experiment and recognize the emotional behavior of dogs. To broaden our conclusions, in our research study we compare our system with other systems of different architectures. In addition, we also use modern transfer learning with augmentation and data normalization techniques. The results show that VGG16 and VGG19 are the most suitable backbone networks. Therefore, a certain deep neural network, named mVGG16, based on the suboptimal VGG16 has been created, trained and fine-tuned with transfer (without augmentation and normalization). The developed system is then tested against an internal test dataset. In addition, to show the robustness of the system, a set of external data outside the breed is also taken into account. Being able to detect unsafe dog behavior and rely on a generalization for other breeds is worth popularizing. Equally important are the possible applications of the system to monitor the behavior of pets in the absence of their owners.

  • Cathodic Activation of Titania-Fly Ash Cenospheres for Efficient Electrochemical Hydrogen Production: A Proposed Solution to Treat Fly Ash Waste
    • Tariq Altalhi
    • Amine Mezni
    • Mohamed Ibrahim
    • Moamen Refet
    • Adil Gobouri
    • Ayham Safklou
    • Adel Mousli
    • Mohamed Attia
    • Purna Boruah
    • Manash Das
    • Jacek Ryl
    • Rabah Boukherroub
    • Amin Mohammed
    2022 Pełny tekst Catalysts

    Fly ash (FA) is a waste product generated in huge amounts by coal-fired electric and steam-generating plants. As a result, the use of FA alone or in conjunction with other materials is an intriguing study topic worth exploring. Herein, we used FA waste in conjunction with titanium oxide (TiO2) to create (FA-TiO2) nanocomposites. For the first time, a cathodic polarization pre-treatment regime was applied to such nanocomposites to efficiently produce hydrogen from an alkaline solution. The FA-TiO2 hybrid nanocomposites were prepared by a straightforward solvothermal approach in which the FA raw material was mixed with titanium precursor in dimethyl sulfoxide (DMSO) and refluxed during a given time. The obtained FA-TiO2 hybrid nanocomposites were fully characterized using various tools and displayed a cenosphere-like shape. The synthesized materials were tested as electrocatalysts for the hydrogen evolution reaction (HER) in 0.1 M KOH solution in the dark, employing various electrochemical techniques. The as-prepared (unactivated) FA-TiO2 exhibited a considerable HER electrocatalytic activity, with an onset potential (EHER) value of −144 mV vs. RHE, a Tafel slope (−bc) value of 124 mV dec−1 and an exchange current density (jo) of ~0.07 mA cm−2. The FA-TiO2′s HER catalytic performance was significantly enhanced upon cathodic activation (24 h of chronoamperometry measurements performed at a high cathodic potential of −1.0 V vs. RHE). The cathodically activated FA-TiO2 recorded HER electrochemical kinetic parameters of EHER = −28 mV, −bc = 115 mV dec−1, jo = 0.65 mA cm−2, and an overpotential η10 = 125 mV to yield a current density of 10 mA cm−2. Such parameters were comparable to those measured here for the commercial Pt/C under the same experimental conditions (EHER = −10 mV, −bc = 113 mV dec−1, jo = 0.88 mA cm−2, η10 = 110 mV), as well as to the most active electrocatalysts for H2 generation from aqueous alkaline electrolytes

  • Cathodic Protection System of the Spiral Classifier at the KGHM Polska Miedź S.A. Ore Concentration Plant—Case Study of Commissioning and Control of Operating Parameters
    • Marcin Czekajło
    • Krzysztof Żakowski
    2022 Pełny tekst Minerals

    The project involved designing, constructing and commissioning a cathodic protection system for a selected spiral classifier operating at the KGHM Polska Miedź S.A. Ore Concentration Plant (O/ZWR). The authors developed a concept and assumptions regarding the corrosion protection of a large industrial device using a cathodic protection system with an external power source. Pre-project studies included conducting a trial polarization of one of the 28 classifiers operating at O/ZWR. The obtained results enabled the determination of the protective current demand re-quired and the selection of a target polarization device, ensuring the flow of current with an in-tensity that guarantees that the required corrosion protection level will be achieved. The ulti-mately installed cathodic protection system consisted of an external cathodic protection current source with maximum output parameters of 50V/20A, a power supply system and a polarization anode system. Elements for monitoring corrosion occurring during system operation were in-stalled, which employed reference electrodes of zinc (Zn) and silver chloride (Ag/AgCl) to measure the potential of the structure under cathodic protection. Furthermore, resistive corro-sion sensors were installed to measure the steel corrosion rate under polarization conditions, making it possible to assess the effectiveness of the protection. The system will also be equipped with a prototype system for remote monitoring of the operation of the protection system, ena-bling online observation and analysis of settings and temporary indicators influencing the on-going corrosion processes.

  • Cattaneo–Christov heat flow model for copper–water nanofluid heat transfer under Marangoni convection and slip conditions
    • Khalid Abdul khaliq M.A Alharbi
    • Naseer Mohammad Alshahrani
    • Naeem Ullah
    • Mohammad Naseer Khan
    • Marek Krawczuk
    • Abd Allah Mousa
    • Sajid Ali
    2022 Pełny tekst Scientific Reports

    This report is devoted to the study of the flow of MHD nanofluids through a vertical porous plate with a temperature-dependent surface tension using the Cattaneo–Christov heat flow model. The energy equation was formulated using the Cattaneo–Christov heat flux model instead of Fourier’s law of heat conduction. The Tiwari–Das model was used to take into account the concentration of nanoparticles when constructing the momentum equation. The problem is described mathematically using the boundary layer approach as a PDE, which is then converted into an ODE with the help of the transformation process. The solution finding process was completed by running the bvp4c code in MATLAB. A quantitative analysis of the influence of some newly occurring parameters on physical quantities was carried out using graphics. The addition of nanoparticles to the base fluid leads to an increase in both skin friction and thermal conductivity. The increase in thermal conductivity is the advantage, while the increase in skin friction is the disadvantage of the nanoparticle concentration. Marangoni convection has proven to be one of the most cost-effective tools available that can reduce skin friction. Marangoni convection improves the heat transfer coefficient during suction but decreases the heat transfer coefficient during the injection.

  • Cavitation based cleaner technologies for biodiesel production and processing of hydrocarbon streams: A perspective on key fundamentals, missing process data and economic feasibility – A review
    • Elvana Çako
    • Zhaohui Wang
    • Roberto Castro-Muñoz
    • Manoj P Rayaroth
    • Grzegorz Boczkaj
    2022 Pełny tekst ULTRASONICS SONOCHEMISTRY

    The present review emphasizes the role of hydrodynamic cavitation (HC) and acoustic cavitation in clean and green technologies for selected fuels (of hydrocarbon origins such as gasoline, naphtha, diesel, heavy oil, and crude oil) processing applications including biodiesel production. Herein, the role of cavitation reactors, their geometrical parameters, physicochemical properties of liquid media, liquid oxidants, catalyst loading, reactive oxygen species, and different types of emulsification and formation of radicals, formation as well as extraction of formed by-products are systematically reviewed. Among all types of HC reactors, vortex diode and single hole orifices revealed more than 95 % desulfurization yield and a 20 % viscosity reduction in heavy oil upgrading, while multi-hole orifice (100 holes) and slit Venturi allowed obtaining the best biodiesel production processes in terms of high (%) yield, low cost of treatment, and short processing time (5 min; 99 % biodiesel; 4.80 USD/m3). On the other hand, the acoustic cavitation devices are likely to be the most effective in biodiesel production based on ultrasonic bath (90 min; 95 %; 6.7 $/m3) and desulfurization treatment based on ultrasonic transducers (15 min; 98.3 % desulfurization; 10.8 $/m3). The implementation of HC-based processes reveals to be the most cost-effective method over acoustic cavitation-based devices. Finally, by reviewing the ongoing applications and development works, the limitations and challenges for further research are addressed emphasizing the cleaner production and guidelines for future scientists to assure obtaining comprehensive data useful for the research community.

  • Cavitation-Based Processes for Water and Wastewater Treatment
    • Kirill Fedorov
    • Elvana Cako
    • Kumaravel Dinesh
    • Reza Darvishi Cheshmeh Soltani
    • Zhaohui Wang
    • Javed Ali Khan
    • Grzegorz Boczkaj
    2022 Pełny tekst

    Cavitation based on advanced oxidation processes (Cav-AOPs) is interesting alternatives for already implemented wastewater treatment technologies. Destructive and strongly undesirable phenomena in the industry, i.e., cavitation, revealed to be useful in a positive manner as a source of energy for chemical reactions. During the implosion of cavitation bubbles, focused energy and resulting high temperature and pressure allows to effectively degrade many chemical compounds present in the cavitated liquid phase. The main reactions taking place in the cavitation zone are the thermal decomposition of chemical moieties as well as oxidation with dissolved oxygen and hydroxyl radicals produced during the implosion of cavitation bubbles. Great interest on this topic is supported by an increased number of publications dedicated to several aspects relating to the formation of cavitation phenomena and its application for water and wastewater treatment as well as hybrid processes based on external oxidants providing effective formation of radical species in cavitation conditions. In this chapter, a state of the art of cavitation-based water treatment technologies, including AOPs, as well as recent trends in this field is discussed. The principles of cavitation combined with AOPs are presented, followed by the evaluation of their effectiveness in the oxidation of organic contaminants. A comparison of hydrodynamic and acoustic cavitation processes for the same type of pollutants has been discussed. For example, the sanitization (disinfection) of water, as well as the degradation of pollutants including sulfide ions and several groups of organic compounds such as sulfur, nitrogen, and oxygen-containing organic compounds, aromatic hydrocarbons, dyes, and pharmaceuticals, has been taken into account while comparing the different cavitation processes.

  • Cavity-expansion approximation for projectile impact and penetration into sand
    • V Kotov
    • Anatoly Bragov
    • V Balandin
    • Leonid Igumnov
    • Andrey Lomunov
    • Victor Eremeev
    • Antonio Cazzani
    2022 Pełny tekst CONTINUUM MECHANICS AND THERMODYNAMICS

    A one-dimensional problem of a spherical cavity expanding at a constant velocity from zero initial radius in an infinite granular medium, which has the first-kind self-similar solution, is considered. We are solving this dynamic spherical cavity-expansion problem to model rigid spheres penetrating into a granular media. Elastic–plastic deformation of the granular media is described in a barotropic approximation, using the high-pressure equation of state and Mohr–Coulomb Tresca’s limit yield criterion. The medium is assumed to be incompressible behind the shock wave front propagating through the unperturbed medium. The problem in this formulation was solved analytically. Besides, a generalized solution of the problem was obtained numerically, which involves transition of a continuous elastic–plastic wave into a plastic shock wave when pressure grows with the cavity expansion velocity. The comparison of the analytical and numerical solutions shows that a linearized analytical solution is a good approximation of the pressure along the boundary of the cavity as a function of its expansion, except for low velocities. The linearized rigid plastic solution can be used for analyzing resistance to a rigid sphere that penetrates into the granular media. The computational results are compared with known experimental relations for resistance to spherical projectiles penetrating dry and water-saturated sand. Good agreement between the numerical and experimental results is obtained without any correction factors.