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Tytuł:
An Application of Anaerobic-Aerobic Combined Bioreactor Efficiency in COD Removal
Autorzy:
Kavousi, Rezvan
Borghei, Seyyed Mehdi
Powiązania:
https://bibliotekanauki.pl/articles/27314286.pdf
Data publikacji:
2023
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
hydraulic loading
anaerobic-aerobic combined reactors
COD removal
fixed bed bioreactor
Kaldnes packing
municipal wastewater
industrial wastewater
Opis:
Over the past few decades, anaerobic-aerobic wastewater treatment systems have been widely used in industrial and municipal wastewater treatment. This study was conducted to examine the effects of combined anaerobic-aerobic bioreactors in the removal of chemical oxygen demands (COD) while reducing phosphate concentrations in synthetic wastewater. In this project, a bioreactor with the dimensions of 10 cm × 10 cm × 80 cm with respective Kaldnes packing ratios of 90 and 30% for the anaerobic and aerobic sections was designed. A combined anaerobic-aerobic reactor’s structure made changing hydraulic retention times only possible by adjusting the volume of its aerobic and anaerobic sections. In the first case, the anaerobic and aerobic sections of the reactor occupied 30 and 50 cm of its height, respectively. The height of the anaerobic section decreases to 12.5 cm in the second case. In aerobic and anaerobic sections, pH was within a neutral range, temperature was 37°C. MLSS (mixed liquor suspended solids) was 1220 and 1030 mg/L, and attached growth was 743 and 1190 mg/L respectively. In order to evaluate COD in the wastewater, three different initial phosphorus concentrations were tested: 12.8, 32.0 and 44.8 mg/L, as well as four COD: 500, 1000, 1200 and 1400 mg/L. Considering the results, COD removal is greater than 80% when the valve 2 is in the anaerobic section outlet regardless of the concentration of phosphate. In this case, the best result is for inlet COD of 500, where the reactor can eliminate more than 90%. When the COD concentration reaches 1000 to 1400 ppm, the reactor’s COD removal efficiency declines to 60%.
Źródło:
Geomatics and Environmental Engineering; 2023, 17, 4; 5--18
1898-1135
Pojawia się w:
Geomatics and Environmental Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of Anaerobic-Aerobic Combined Bioreactor in Phosphorus Removal
Autorzy:
Kavousi, Rezvan
Borghei, Seyyed Mehdi
Powiązania:
https://bibliotekanauki.pl/articles/27314276.pdf
Data publikacji:
2023
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
phosphorus removal
hydraulic loading
anaerobic-aerobic combined bioreactor
kaldnes packing
municipal wastewater
industrial wastewater
Opis:
A two-stage anaerobic-aerobic sequencing reactor system was developed in order to enhance the removal of biological phosphorus in the sequencing of combined reactors. Combining both aerobic and anaerobic designs in one reactor improved the efficiency and reduced the construction and operating costs. The combination of an upflow anaerobic fixed bed (UAFB) and a floating activated sludge aerobic bioreactor was designed with respective Kaldnes packing ratios of 90 and 30% for the anaerobic and aerobic sections. The controlled parameters were pH levels within a neutral range, a temperature of 37°C, mixed liquor suspended solids (MLSS) of 1220 and 1030 mg/L for the aerobic and anaerobic sections, respectively, and an attached growth that was equal of 743 and 1190 mg/L for the aerobic and anaerobic sections, respectively. Tests were conducted for three different initial phosphorus concentrations (12.8, 32.0, and 44.8 mg/L), two different volumes for each section, and four chemical oxygen demands (CODs) (500, 1000, 1200, and 1400 mg/L). The results demonstrated that, generally, the phosphorus removal in the anaerobic section fell significantly by increasing the inlet COD, and the maximum removal occurred at COD = 500 mg/L. More than 90% of the phosphorus was removed in the aerobic section at COD = 500 mg/L. In other words, the best performance of the reactor was when the ratio of the COD : N : P = 100 : 5 : 2, composition of phosphorus in industrial wastewater.
Źródło:
Geomatics and Environmental Engineering; 2023, 17, 6; 111--127
1898-1135
Pojawia się w:
Geomatics and Environmental Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Assessment of Asymmetrical Lower Limb Loading in the Short-Track Speed Skaters
Autorzy:
Kaczorowska, Antonina
Dajczak, Magdalena
Mroczek, Agata
Lepsy, Ewelina
Powiązania:
https://bibliotekanauki.pl/articles/2192854.pdf
Data publikacji:
2023
Wydawca:
Uniwersytet Szczeciński. Wydawnictwo Naukowe Uniwersytetu Szczecińskiego
Tematy:
short-track speed skaters
loading symmetry index
asymmetry of lower limb loading
Opis:
Background. Short-track speed skaters who regularly participate in training are exposed to the occurrence of asymmetry in the lower limb loading. Objective. The study aimed to assess the symmetry of the lower limb loading in short track skaters and the relationship between age, training experience and anthropometric variables and symmetry of lower limb loading. Methods. The examined group consisted of 20 short-track speed skaters (12 men and 8 women), and the control group comprised 28 university students (14 men and 14 women). Two scales were used to assess the symmetry of lower limb loading, and the lower limb's loading symmetry index (LSI) was calculated. Results. In the studied groups 65% of skaters and 82% of students have LSI within the normal range. Most short-track speed skaters (85%) put weight on the right lower limb, and there was no clear trend among students (p < 0.001). In the group of skaters, the majority of men (83%) properly loaded their lower limbs, compared to 37.5% of women (p = 0.036). In short-track speed skaters, positive correlations were found between LSI and the age and length of training. Conclusions. Long-term asymmetric loading of the lower limbs in short-track speed skaters causes the advantage of the load on the right lower limb and increases the asymmetry of the load on the lower limbs, especially in women.
Źródło:
Central European Journal of Sport Sciences and Medicine; 2023, 41; 61-68
2300-9705
2353-2807
Pojawia się w:
Central European Journal of Sport Sciences and Medicine
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Assessment of cargo handling operation efficiency in the Clarion-Clipperton Zone for standard bulk carriers in the view of significant amplitudes of roll as a limiting criterion
Autorzy:
Kacprzak, Paweł
Powiązania:
https://bibliotekanauki.pl/articles/29521031.pdf
Data publikacji:
2023
Wydawca:
Akademia Morska w Szczecinie. Wydawnictwo AMSz
Tematy:
bulk carrier
loading operations
roll
effectiveness factor
Clarion-Clipperton Zone
Opis:
Experienced ship roll during loading is the easiest parameter to observe and measure on board of a loaded ship. Therefore, the ship’s significant roll amplitudes should be the key limiting factor in view of the safety and efficiency of cargo handling operations at sea. For the example of three standard bulk carriers, the authors prepared a method of assessment of bulk carrier suitability to perform safe and efficient cargo handling operations in the Clarion-Clipperton Zone in view of significant amplitudes of roll. Via a calculation of the efficiency index for a set of limiting amplitudes of roll during loading simulation, we are able to analyze ship effectiveness. The application of the above-mentioned method can be employed as a useful tool to predict the lowest allowable significant amplitudes of roll when the required efficiency level is specified. Additionally, a calculation is made for the operable days where cargo operations are possible. Investigations show that, according to applied criteria, the effectiveness drops, and not every bulk carrier can perform safe cargo handling operations at sea.
Źródło:
Zeszyty Naukowe Akademii Morskiej w Szczecinie; 2023, 74 (146); 55-64
1733-8670
2392-0378
Pojawia się w:
Zeszyty Naukowe Akademii Morskiej w Szczecinie
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Development of the statistical model failure of orthotropic composite materials
Autorzy:
Kvit, Roman
Powiązania:
https://bibliotekanauki.pl/articles/24201506.pdf
Data publikacji:
2023
Wydawca:
Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
Tematy:
stochasticity
probability of failure
orthotropic composite material
failure loading
integral probability distribution function
stochastyczność
prawdopodobieństwo uszkodzenia
ortotropowy materiał kompozytowy
całkowa funkcja rozkładu prawdopodobieństwa
Opis:
A composite plate (matrix and reinforcing elements) under conditions of plane deformation is considered. According to the elastic properties, the material of the plate is considered orthotropic with uniformly distributed defects-cracks that do not interact with each other. The geometric characteristics of defects are statistically independent random variables – the half-length and the orientation angle between the defect line and the axis of orthotropy with a larger Young’s modulus. The ratio for the failure loading integral probability distribution function of the composite was obtained. The dependencies of the researched composite probability of failure (reliability) for the different number of cracks (plate sizes), different types of loading and various values of the exponential distribution parameter are calculated and investigated graphically.
Źródło:
Journal of Applied Mathematics and Computational Mechanics; 2023, 22, 2; 26--35
2299-9965
Pojawia się w:
Journal of Applied Mathematics and Computational Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Earthquake protection of reinforced concrete structures with infill walls using PUFJ and FRPU systems
Ochrona przed trzęsieniami ziemi konstrukcji żelbetowych ze ścianami wypełniającymi przy użyciu systemów PUFJ i FRPU
Autorzy:
Kwiecień, Arkadiusz
Akyildiz, Ahmet Tugrul
Powiązania:
https://bibliotekanauki.pl/articles/27312152.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
ochrona sejsmiczna
obciążenie cykliczne
obciążenie rezonansowe
złącze polimerowe podatne
badanie dynamiczne
stół sejsmiczny
PUFJ
poliuretan wzmocniony włóknami
rama żelbetowa
ściana wypełniająca
anti-seismic protection
cyclic loading
resonance loading
polymer flexible joint
dynamic test
shake table
fiber reinforced polyurethane
reinforced concrete frame
infill wall
Opis:
Advancements in technology and material sciences lead new solutions to be used in civil engineering. PolyUrethane Flexible Joints (PUFJ) and Fiber Reinforced PolyUrethanes (FRPU) are among those innovative solutions. PUFJ implemented systems comprise of seismic preventive buffer material between masonry infill walls and reinforced concrete (RC) frames, whereas FRPU solution is designed for covering the wall surfaces with thin composite strips. Both methods are primarily developed for increasing the ductility capacities of buildings while sustaining the overall structural strength without compromising on the safety of these systems against earthquakes. In this article, test results of the quasi-static cyclic experiments as well as dynamic tests on the shake tables including harmonic forces operating in resonance are presented. Moreover, numerical analyses are performed in order to comprehend the behavior of PUFJ implemented frames constituted with different masonry materials than above which are under various loading conditions. The outcomes confirmed the high efficiency of the proposed solutions, which at the same time meet the strict requirements of the modern seismic standards.
Postępy w technologii i materiałoznawstwie prowadzą do nowych rozwiązań wprowadzanych w inżynierii lądowej. Wśród tych innowacyjnych rozwiązań znajdują się podatne złącza poliuretanowe (PUFJ) i poliuretany wzmocnione włóknami (FRPU). Systemy PUFJ instalowane są pomiędzy murowanymi ścianami wypełniającymi a ramami żelbetowymi jako anty-sejsmiczny element buforowy, natomiast systemy FRPU są przeznaczone do wzmacniania powierzchni ścian cienkimi pasami kompozytowymi. Obie metody zostały opracowane w celu zwiększenia ciągliwości budynków, przy jednoczesnym utrzymaniu ich ogólnej nośności, a tym samym w celu zwiększenia bezpieczeństwa użytkowania tych budynków w trakcie trzęsień ziemi. W artykule przedstawiono wyniki badań elementów w skali naturalnej pod quasi-statycznymi obciążeniami cyklicznymi oraz obciążeniami dynamicznymi na stole sejsmicznym i pod działaniem sił harmonicznych w rezonansie. Ponadto zostały przeprowadzone analizy numeryczne, mające na celu poznanie zachowania się podobnych konstrukcji z innymi materiałami murowymi współpracującymi z PUFJ, które poddane zostały różnym warunkom obciążenia. Wyniki potwierdziły wysoką skuteczność proponowanych rozwiązań, które jednocześnie spełniają surowe wymagania współczesnych norm sejsmicznych.
Źródło:
Archives of Civil Engineering; 2023, 69, 3; 199--216
1230-2945
Pojawia się w:
Archives of Civil Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fatigue Resistance and Other Utility Properties of NiMn-Type of Austenitic Nodular Cast Iron
Autorzy:
Vaško, Alan
Uhríčik, Milan
Kaňa, Václav
Powiązania:
https://bibliotekanauki.pl/articles/27707054.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
Ni-Resist
austenitic nodular cast iron
EN-GJSA-XNiMn13-7
fatigue
push-pull loading
Opis:
The aim of this paper is to evaluate the fatigue resistance of austenitic nodular cast iron and to compare it with other types of nodular cast irons. The austenitic nodular cast iron, used for the experiments, was alloyed by 13% nickel and 7% manganese (EN-GJSA-XNiMn13-7) to obtain an austenitic matrix. The microstructure was studied using light metallographic microscopy. Mechanical properties were investigated by tensile test, impact bending test and Brinell hardness test. Fatigue tests were carried out at sinusoidal cyclic push-pull loading at ambient temperature. The results of fatigue tests were compared with the fatigue properties of ferrite-pearlitic nodular cast iron and pearlite-ferritic nodular cast iron. Experimental results show that NiMn-type of austenitic nodular cast iron has lower tensile strength and hardness, but higher elongation and absorbed energy than the compared types of nodular cast iron. However, austenitic nodular cast iron has lower fatigue limit.
Źródło:
Archives of Metallurgy and Materials; 2023, 68, 2; 563--569
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Metal-organic frameworks for efficient drug adsorption and delivery
Autorzy:
Hyjek, Kornelia
Jodłowski, Przemysław
Powiązania:
https://bibliotekanauki.pl/articles/35134841.pdf
Data publikacji:
2023
Wydawca:
Radomskie Towarzystwo Naukowe
Tematy:
drug delivery systems
metal-organic frameworks
synthesis
characterization
drug loading
biocompatibility
systemy dostarczania leków
sieć metalo-organiczna
synteza
charakterystyka
akumulacja leku
biokompatybilność
Opis:
In recent years, the number of materials used as drug delivery systems (DDS) has increased dramatically. The widespread use of DDSs has improved both the safety and efficacy of therapy. The systems currently in use pose numerous drawbacks and require proper improvements. Although many modern materials are being developed, metal-organic frameworks (MOFs) deserve special attention. Thermal and chemical stability, high specific surface area, low toxicity, high biocompatibility, and great potential for modification are the main features enabling MOFs to be used as DDS. In this review, we describe MOFs, their structure, synthesis, and characterization, as well as drug loading, drug release kinetics, and bioassays. A critical approach is to outline the disadvantages as well as the limitations of MOFs and to identify areas that need to be studied more thoroughly. Nonetheless, the prospective nature of MOFs as DDS and potential adsorbents in overdose or poisoning is presented and highlighted.
Źródło:
Scientiae Radices; 2023, 2, 2; 115-189
2956-4808
Pojawia się w:
Scientiae Radices
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A heuristic approach to optimizing the loading of homogeneous marine cargo
Autorzy:
Bernardelli, Michał
Powiązania:
https://bibliotekanauki.pl/articles/2175836.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
large-scale optimization
cargo loading
heuristic
marine transportation
suboptimality
Opis:
In this article, the optimal loading of homogeneous marine cargo is considered. A mathematical formulation in terms of a mixed-integer linear program can be given. Still, the level of complexity turns out to be too high to perform full-scale computations. On the one hand, the reasons for this are the multitude of variables and constraints. On the other hand, feasible solutions to such problems may often be economically unacceptable or simply empty. Therefore, a heuristic is presented, according to which the relaxation of the limiting conditions influencing the solution’s feasibility and its economic profitability was parametrized. Under this heuristic, shifting the deadlines of selected orders is allowed. Also, the assignment of orders to vessels is separated from the allocation of vessels to piers in loading and unloading ports. The solution presented can be easily generalized by adding additional restrictions or features like indirect vessels, founding cost, or differentiation between materials.
Źródło:
Operations Research and Decisions; 2022, 32, 2; 1--15
2081-8858
2391-6060
Pojawia się w:
Operations Research and Decisions
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Aeroacoustic analysis based on FW–H analogy to predict low-frequency in-plane harmonic noise of a helicopter rotor in hover
Autorzy:
Suresh, T.
Szulc, O.
Flaszynski, P.
Powiązania:
https://bibliotekanauki.pl/articles/38695686.pdf
Data publikacji:
2022
Wydawca:
Instytut Podstawowych Problemów Techniki PAN
Tematy:
Lighthill’s analogy
Farassat’s formulation
blade element momentum theory
computational aeroacoustics
computational fluid dynamics
thickness noise
monopole
loading noise
dipole
Opis:
The integral formulation of the Ffowcs-Williams and Hawkings (FW–H) analogy, developed by Farassat (known as Farassat’s formulation 1A), is implemented to study the sound generation and propagation of rotating slender bodies. The general post-processing numerical code utilizes the linear acoustic theory to predict the thickness and loading noise terms for bodies in subsonic motion. The developed numerical code is validated for elementary acoustic sources (rotating monopole and dipole) against analytical solutions. The validated code is then applied for prediction of lowfrequency in-plane harmonic noise (LF-IPH) of a model helicopter rotor of Sargent and Schmitz in a low-thrust hover with full-scale tip Mach number. The required loading distribution of the rotor blade is obtained with CFD (RANS) and Blade Element Momentum Theory (BEMT) methods and also validated against literature data. The developed acoustic code, supplemented by CFD and BEMT loading analyses, allows for a detailed comparison (thickness and loading, near- and far-field, etc.) of the LFIPH noise of a helicopter rotor in both, time and frequency domains. The predicted (FW–H) acoustic signals are compared not only with the reference code solutions, but also with the experimental data. Moreover, the paper quantifies the impact of computational grid density and time-step size (used by CFD and FW–H codes) on the final solution accuracy. Additionally, a simplified analytical code is developed (based on elementary dipole solutions, compact chord assumption and BEMT method) allowing for the initial loading noise analysis with highly reduced computational resources. The acquired results are fully compatible with the classical FW–H analysis in terms of the impact of the in-plane and out-of-plane forces on the generated noise. The FW–H code predictions of the acoustic pressure and its components are in satisfactory agreement with the reference and experimental data of Sargent and Schmitz.
Źródło:
Archives of Mechanics; 2022, 74, 2-3; 201-246
0373-2029
Pojawia się w:
Archives of Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of deflection in visco-thermoelastic beam resonators subjected to harmonic loading
Autorzy:
Chopra, Deepti
Singh, Prince
Powiązania:
https://bibliotekanauki.pl/articles/2174186.pdf
Data publikacji:
2022
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
termoelastyczność
transformata Laplace'a
belka
obciążenie
visco-thermoelastic
beam
loading
Laplace transform
Opis:
This paper analyses the transverse deflection in a homogeneous, isotropic, visco-thermoelastic beam when subjected to harmonic load. The ends of the beam are considered at different boundary conditions (both axial ends clamped, both axial ends simply supported and left end clamped and right end free). The deflection has been studied by using the Laplace transform. Numerical computation of analytical expression of deflection obtained after Inverse Laplace transform has been done using MATLAB software. The graphical observations have been discussed under various boundary conditions for different values of time and length. The above work has applications in design of resonators.
Źródło:
International Journal of Applied Mechanics and Engineering; 2022, 27, 2; 35--52
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Assessment of Factors Contributing to the Risks of Cargo Liquefication Accident in Bulk Carriers (A Qualitative Approach)
Autorzy:
Nwigwe, T.
Minami, K.
Powiązania:
https://bibliotekanauki.pl/articles/2172467.pdf
Data publikacji:
2022
Wydawca:
Uniwersytet Morski w Gdyni. Wydział Nawigacyjny
Tematy:
bulk carriers
cargo liquefication
risk of cargo liquefication
loading plan
liquidation problem
bulk carrier accidents
assessment of risk
Opis:
Liquidation of cargo in bulk carrier has been identifying as a major hazard affecting the bulk carrier shipping and has resulted to several loss of lives. This study assesses the liquidation problem in bulk carrier shipping, it also discusses the mechanisms by which cargo liquefaction occurs in bulk carrier and the factors influencing the risks of occurrence, based on a qualitative approach. Based on the findings and survey, the unsafe storage condition, poor compliance with the testing and certification of cargoes, poor loading plan, have been identify as some of the root casual factors influencing the risk of liquidation problem in bulk carrier. This study will contribute to increasing the awareness and understanding of the problem of cargo liquefaction and will facilitate the development of regulations that reflects the realities of this problem and assist in the development of future recommendations for mitigation plans against the liquidation problem in bulk carrier.
Źródło:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2022, 16, 1; 149--152
2083-6473
2083-6481
Pojawia się w:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Behavior of Vertically Confined Square Footing on Reinforced Sand under Centric Inclined Loading
Autorzy:
Kirtimayee, B.
Samadhiya, Narendra Kumar
Powiązania:
https://bibliotekanauki.pl/articles/2172877.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
centric inclined loading
load intensity
settlement
geogrid
sand
square footing
Opis:
This study presents the behavior of vertically confined square footing on geogrid-reinforced sand under centric inclined loading through a series of experimental tests. The load was applied at 5°, 10° and 20° angles of inclination with the vertical. The tests were conducted on surface footing, footing with confiner and footing with confiner and horizontal reinforcement configurations subjected to inclined loading. Parametric variations like depth of the confiner (d=1B, 1.5B, 2B), number of geogrid layers (N; varies with variation in depth of confiner), and spacing between horizontal reinforcements (Y=0.25B, 0.5B, 0.75B, 1B) have been investigated at the top surface dimension of confiner (D) as 1.0B, 1.5B and 2.0B (where B is the width of the model footing). Results show that combined effect of confiner and horizontal reinforcement increases the ultimate bearing capacity of footing significantly compared to only confiner for all angle of inclinations. It can also be observed that load bearing capacities decrease with increase in angles of inclination and record the minimum improvement at 20° angle of inclination. Improvement in bearing capacities and reduction in settlement of footing analyzed in terms of bearing capacity ratio (BCR) and settlement reduction factor (SRF) are compared for all footing configurations. To summarize, the test results showed that confiner along with reinforcement can be considered as an economic ground improvement technique for shallow foundations to counter against heavily inclined loading.
Źródło:
Studia Geotechnica et Mechanica; 2022, 44, 3; 224--238
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Development of an advanced constitutive model for spoil-structure interaction problems
Opracowanie zaawansowanego modelu konstytutywnego dla oddziaływań zwałowisko-konstrukcja budowlana
Autorzy:
Doan, Nhat-Phi
Liakou, Anna
Garala, Thejesh Kumar
Cui, Ge
Kantesaria, Naman
Halder, Koushik
Heron, Charles M.
Marshall, Alec M.
Powiązania:
https://bibliotekanauki.pl/articles/2175654.pdf
Data publikacji:
2022
Wydawca:
Poltegor-Instytut Instytut Górnictwa Odkrywkowego
Tematy:
spoil
numerical modelling
constitutive model
rocking
cyclic loading
zwałowisko
modelowanie numeryczne
model konstytutywny
przechylenie
obciążenie cykliczne
Opis:
Revitalisation options for mine spoil heaps is an important issue to consider when planning for post-mining land use. One option is the installation of wind turbines on the spoil heaps, which provide a sustainable energy source. This option poses challenges for foundation design due to the nature of the spoil material, which is usually highly heterogeneous due to the way spoils are deposited, and can contain high proportions of high-plasticity cohesive soils (clay). This paper presents results obtained using an advanced constitutive model that was developed to simulate cohesive mine spoil behaviour and presents model results for the prediction of foundation response under both monotonic and cyclic loading. The model is a modified version of the original isotropic bounding surface plasticity model that additionally involves a damaged-based plastic modulus in order to realistically represent soil strength degradation induced by cyclic action. The model is used for the simulation of shallow foundations for onshore wind turbines on a cohesive clay with a heterogeneous (linearly increasing) undrained shear strength (random spatial variability is not considered). Two different loading scenarios of a shallow strip foundation are considered in the paper: a pure moment-vertical loading (M-V), and a moment-horizontal-vertical loading (M-H-V). The effect of the adopted spoil-foundation interface type is also considered: (1) a fully-bonded interface and (2) a tensionless interface. Results demonstrate that, though the vertical bearing capacity is only slightly affected by the interface properties, the moment capacity is shown to be strongly influenced by the predefined contact conditions. For the footing system under M-H-V loading, a dominant footing uplift mechanism is obtained for light structures and the opposite holds for heavily loaded structures, where significant settlement accumulation occurs during cyclic loading. Based on the analysis, the moment bearing capacity of the footing system decreases as the slenderness ratio and/or the vertical safety factor increase, and the opposite mechanism is obtained as the strength heterogeneity degree increases.
Możliwości rewitalizacji zwałowisk są ważnym zagadnieniem przy planowaniu zagospodarowania terenów pogórniczych. Jedną z opcji jest instalacja na hałdach turbin wiatrowych, które stanowią zrównoważone źródło energii. Opcja ta stanowi wyzwanie dla projektowania fundamentów biorąc pod uwagę charakter materiału zwałowego, który ze względu na sposób deponowania jest zwykle wysoce niejednorodny i może zawierać dużo wysokoplastycznych gruntów spoistych (iłów). W artykule przedstawiono wyniki uzyskane przy użyciu zaawansowanego modelu konstytutywnego, który został opracowany w celu symulacji zachowania spoistego materiału zwałowego oraz zaprezentowano wyniki modelowania dla przewidywania reakcji fundamentu będącego zarówno pod obciążeniem monotonicznym jak i cyklicznym. Model jest zmodyfikowaną wersją oryginalnego izotropowego modelu plastyczności powierzchni granicznej, który dodatkowo zawiera moduł plastyczności oparty na zniszczeniu w celu realistycznego przedstawienia degradacji wytrzymałości gruntu wywołanej działaniem cyklicznym. Model jest wykorzystywany do symulacji płytkich fundamentów turbin wiatrowych na iłach spoistych o niejednorodnej (liniowo wzrastającej) wytrzymałości na ścinanie bez odpływu (nie uwzględniono losowej zmienności przestrzennej). W pracy rozpatrzono dwa różne scenariusze obciążenia płytkiej ławy fundamentowej: czyste obciążenia moment-pionowe (M-V) oraz obciążenia moment-poziome-pionowe (M-H-V). Rozważono również wpływ przyjętego rodzaju styku zwałowisko-fundament: (1) całkowicie związany oraz (2) beznaprężeniowy. Wyniki pokazują, że choć nośność pionowa tylko w niewielkim stopniu zależy od właściwości styku, to okazuje się, że nośność momentu jest silnie uzależniona od zdefiniowanych wcześniej warunków kontaktowych. Dla systemu stopy fundamentowej pod obciążeniem M-H-V, w przypadku lekkich konstrukcji uzyskuje się dominujący mechanizm unoszenia stopy, a w przypadku konstrukcji silnie obciążonych odwrotny, gdzie podczas cyklicznego obciążenia następuje znaczna akumulacja osiadań. Na podstawie przeprowadzonej analizy można stwierdzić, że nośność systemu stopy fundamentowej maleje wraz ze wzrostem współczynnika smukłości i/lub pionowego współczynnika bezpieczeństwa, a odwrotny mechanizm uzyskuje się wraz ze wzrostem stopnia niejednorodności wytrzymałości.
Źródło:
Górnictwo Odkrywkowe; 2022, 63, 3; 43--50
0043-2075
Pojawia się w:
Górnictwo Odkrywkowe
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Estimation of Per Capita Loading and Treated Wastewater Quality Index in Sharkia Governorate, Egypt
Autorzy:
Aboulfotoh, Ahmed
Heikal, Ghada
Powiązania:
https://bibliotekanauki.pl/articles/2086401.pdf
Data publikacji:
2022
Wydawca:
Polskie Towarzystwo Inżynierii Ekologicznej
Tematy:
domestic wastewater
evaluation
per capita loading
water quality
WWQI
wastewater quality index
WWTP
wastewater treatment plant
Opis:
Monthly reports from June 2017 to May 2018 of Twenty-one wastewater treatment plants in Sharkia were evaluated for the following parameters: temperature, pH, total dissolved solids (TDS), total suspended solids (TSS), chemical oxygen demand (COD), biochemical oxygen demand (BOD), nitrate (NO3), oil and grease (O&G) and Dissolved Oxygen (DO) values. The first aim of this study was to estimate the main wastewater per capita pollution generation per day (PCPL) and found that the 90th percentile PCPL for TSS, COD, BOD, NO3 and O&G were equal to 57.42, 91.59, 59.13, 1.64 and 12.39 (g/capita/day) respectively. The second aim was to assess the performance of the WWTPs in the governorate, by calculating of the wastewater quality index (WWQI) of each plant and for the entire governorate which shows that; 2 WWTPs gives a good performance, 9 WWTPs gives a fair performance, 9 WWTPs gives a marginal performance and 1 WWTP is in bad conditions, the average performance all over the governorate is considered marginal. A simple empirical formula had been established to be used for calculation of the WWQI based on the tested parameters using the multiple linear regression and found to be very effective in predicting the WWQI for the WWTPs.
Źródło:
Journal of Ecological Engineering; 2022, 23, 5; 73--80
2299-8993
Pojawia się w:
Journal of Ecological Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 388

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