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Tytuł:
Effects of the microcrack shape, size and direction on the poroelastic behaviors of a single osteon: a finite element study
Autorzy:
Cen, H-P.
Wu, X-G.
Yu, W-L.
Liu, Q-Z.
Yia, Y-M.
Powiązania:
https://bibliotekanauki.pl/articles/306642.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
poroelastyczność
mikropęknięcie
elementy skończone
osteon
poroelasticity
microcrack
finite element
Opis:
In this work, a finite element study is proposed by using the Comsol Multiphysics software to evaluate the effects of microcrack shape, size and direction on the poroelastic behaviors of a single osteon. Methods: This finite element model is established by using the Comsol Multiphysics software, and we just focus on the comparison of the influences of those microcrack geometric parameters on the osteonal fluid pressure and velocity. Results: The results show that: (1) microcracks in the osteon wall can induce a release of the fluid pressure, but enlarge the velocity in this region; (2) equal-area microcrack with ellipsoid-like shape produced a larger fluid pressure and velocity fields in the osteon than that of rectangular shape; (3) in the elliptic microcracks, the longer of the length (major semi-axis) induces a smaller fluid pressure and velocity amplitudes, whereas the width (minor axis) has little effect; (4) the direction of the microcracks (major axial direction) has an limited influence area around about 1/15 of the osteon cross-sectional area. Conclusions: This model permits the linking of the external loads and microcracks to the osteonal fluid pressure and velocity, which can be used for other purpose associate microcracks with the mechanotransduction and bone remodeling.
Źródło:
Acta of Bioengineering and Biomechanics; 2016, 18, 1; 3-10
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Assessing soil environmental capacity on different land uses in a suburban area of Chengdu, China
Autorzy:
Yang, W.-L.
Zhou, W.-Y.
Wan, W.-X.
Gou, S.-Z.
Zhang, J.
Deng, S.-H.
Shen, F.
Wang, Y.-J.
Yang, H.
Luo, L.
Powiązania:
https://bibliotekanauki.pl/articles/207670.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
China
soil pollution
heavy metals
soil
vegetables
Chiny
zanieczyszczenie gleby
metale ciężkie
gleba
warzywa
Opis:
Wenjiang (China) is the area which undertakes high-intensity planting activities. Additionally, the soil environmental capacity has been a hot area of research as it plays a key role in environmental protection planning, environmental impact assessment and sustainable development. In this paper, the static model of soil environmental capacity is employed to investigate the distribution of residual soil environmental capacity in Wenjiang. The results show that the soil environmental capacity of mercury is the largest for industrial land while it is the lowest in garlic-rice planting areas; the soil environmental capacity of arsenic is the largest in city construction land while it is the lowest in ecological conservation zone; the soil environmental capacity of lead is the largest in city construction land while it is the lowest in garlic-rice planting areas; and the soil environmental capacity of chromium is the largest in city construction land while it is the lowest in garlic-rice planting areas.
Źródło:
Environment Protection Engineering; 2019, 45, 2; 55-67
0324-8828
Pojawia się w:
Environment Protection Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A simulator supporting the distribution of the primary subsidy in a faculty at Wroclaw University of Technology
Autorzy:
Rekuć, W.
Szczurowski, L.
Powiązania:
https://bibliotekanauki.pl/articles/406255.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
algorithm for subsidy distribution
simulator
Opis:
Chosen aspects of a simulator supporting the distribution of the primary teaching subsidy in a faculty of Wroclaw University of Technology have been presented. The mathematical equations forming the basis for the algorithm have been analyzed. The general premises of adapting the set of teaching duties within a faculty to this model have been formulated. Various scenarios illustrating how the distribution of this subsidy works in practice have been shown. Introductory results of such simulations (using MS EXCEL) for a chosen scenario have been presented and discussed.
Źródło:
Operations Research and Decisions; 2015, 25, 4; 35-49
2081-8858
2391-6060
Pojawia się w:
Operations Research and Decisions
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On some methods in safety evaluation in geotechnics
Autorzy:
Puła, W.
Zaskórski, Ł.
Powiązania:
https://bibliotekanauki.pl/articles/178170.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
reliability index
random field
Eurocode 7
Opis:
The paper demonstrates how the reliability methods can be utilised in order to evaluate safety in geotechnics. Special attention is paid to the so-called reliability based design that can play a useful and complementary role to Eurocode 7. In the first part, a brief review of first- and second-order reliability methods is given. Next, two examples of reliability-based design are demonstrated. The first one is focussed on bearing capacity calculation and is dedicated to comparison with EC7 requirements. The second one analyses a rigid pile subjected to lateral load and is oriented towards working stress design method. In the second part, applications of random field to safety evaluations in geotechnics are addressed. After a short review of the theory a Random Finite Element algorithm to reliability based design of shallow strip foundation is given. Finally, two illustrative examples for cohesive and cohesionless soils are demonstrated.
Źródło:
Studia Geotechnica et Mechanica; 2015, 37, 2; 17-32
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Distance protection with dynamic thermal line rating enhancement
Autorzy:
Staszewski, Ł.
Rebizant, W.
Powiązania:
https://bibliotekanauki.pl/articles/410531.pdf
Data publikacji:
2012
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
dynamic thermal line rating
distance protection
overload
heat balance
Opis:
As the worldwide analysis of recent wide area cascading failures have shown, very often the main cause of blackout was mal-operation of the third zone of a distance protection relay. The load encroachment and power swing phenomena are the two dire problems to solve when dealing with the third zone of distance protection mal-function. The vast number of blackouts could have been avoided or the consequences lowered if the distance relay had not operated due to controlled impedance encroachment.This paper proposes a new approach to enhance the distance protection relay operation by introducing a new blocking algorithm. The algorithm is based on Dynamic Thermal Line Rating (DTLR) idea to restrain relay from tripping when conditions in electrical power system and weather conditions allow for it.
Źródło:
Present Problems of Power System Control; 2012, 2; 73-84
2084-2201
Pojawia się w:
Present Problems of Power System Control
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Blackout prevention possibility using dynamic thermal line rating
Zastosowanie dynamicznej cieplnej obciążalności linii przesyłowych jako możliwości zapobiegania blackoutom
Autorzy:
Staszewski, Ł.
Rebizant, W.
Powiązania:
https://bibliotekanauki.pl/articles/410569.pdf
Data publikacji:
2011
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
dynamic thermal line rating
blackout prevention
heat equation
Opis:
This paper presents the Dynamic Thermal Line Rating (DTLR) application, based on the heat equations, that makes possible overhead transmission lines operation over their conservatively designed current ratings. The DTLR concept is well known - owing to the CIGRE [1,2] and IEEE [3] standards for overhead bare conductor temperature calculations. However, this phenomenon may not have been used for a purpose of increasing electrical power system stability and thus for blackout prevention. This paper is based on both CIGRE and IEEE standards and presents investigation of the current flow through various conductors. Their temperature and monitoring ambient weather conditions and thermal limits of a conductor are considered. The influence of the weather conditions on the lines flow capacities is presented as a comparison of various types of AFL 6 conductor and various weather conditions. Also the short analysis of the recent blackouts and possibilities of DTLR use are presented. Obtained results are described and conclusions are drawn.
Artykuł przedstawia zastosowanie dynamicznej termicznej obciążalności linii przesyłowych (DTOLP) jako narzędzia umożliwiającego unikanie powstawania lub dalszego rozwoju powstałej już awarii wielkoobszarowej systemu elektroenergetycznego. Sama idea DTOLP jest dobrze znana, dzięki standardom CIGRE i IEEE służącym do obliczeń termicznego stanu przewodu jako funkcji warunków pogodowych oraz przepływającego przez przewód prądu elektrycznego. Na potrzeby artykułu korzystano z obu standardów i zaprezentowano analizę wpływu przepływu prądu w różnych przewodach na ich możliwości przesyłowe w zależności od otaczających je warunków pogodowych. Dodatkowo artykuł podkre sla istotność przeciążeń linii przesyłowych, jako elementu wywołującego lub pogłębiającego awarie wielkoobszarowe oraz możliwość zastosowania dynamicznej termicznej obciążalności linii przesyłowych w celu zapobiegania tym zjawiskom.
Źródło:
Present Problems of Power System Control; 2011, 1; 15-21
2084-2201
Pojawia się w:
Present Problems of Power System Control
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal calculation for distance protection enhancement
Autorzy:
Staszewski, Ł
Rebizant, W
Powiązania:
https://bibliotekanauki.pl/articles/410608.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
dynamic thermal line rating
distance protection
power swing
third zone
Opis:
Worldwide analysis of recent wide area cascading failures has shown that very often their main cause was the mal-operation of the distance protection relay third zone. The load encroachment and power swing phenomena are the two dire problems to solve when dealing with the third zone of distance protection. The vast number of blackouts could have been avoided or the consequences lowered if the distance relay had not operated due to impedance encroachment while there was no risk of further, continuous operation. This paper proposes a way to improve operation of the distance protection relay by introducing a new blocking algorithm that uses the Dynamic Thermal Line Rating (DTLR) to restrain relay from tripping when conditions in electrical power system allow for it.
Źródło:
Present Problems of Power System Control; 2013, 3; s. 83-94
2084-2201
Pojawia się w:
Present Problems of Power System Control
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of grinding characteristics in high-pressure grinding roller (HPGR) and cone crusher (CC)
Autorzy:
Liu, L.
Tan, Q.
Li, W.
Lv, L.
Powiązania:
https://bibliotekanauki.pl/articles/951829.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
HPGR
grinding kinetics
grinding technical efficiency
ultra-crushing
classified grinding
Opis:
We comparatively studied the ball mill grinding characteristics of comminuted hematite products using a high-pressure grinding roll (HPGR) and a conventional cone crusher (CC). The major properties, including grinding kinetics and technical efficiency (Et), were investigated. The parameters in m-th order grinding kinetics were analyzed, and grinding specific rates were visualized. Ore particles experienced three inherent stages in ball grinding mills, that is i) rapid grinding of coarse fraction, ii) dynamic grinding of medium size fraction, and iii) single grinding of medium size fraction. Particles with size -0.043+0.031 mm were used into dynamic grinding stage earlier than particles -0.105+0.043 mm, and then over-grinding of fines occurred easily. Compared with CC products, HPGR products had significantly shorter turning time points in three breakage stages, implying that HPGR products were ground faster with earlier occurrence of fines over-grinding. HPGR products gave lower Et at a decreasing rate than the CC products for -2.0 mm and -0.5 mm feeds. Then, it showed a slightly higher value of Et for -2.0+0.5 mm feed. This indicated that fines over-grinding in HPGR full-size products were more serious under the condition of coarse grinding, whereas the efficiency was higher, and over-grinding weakened significantly in HPGR coarse products because of screening-out fines.
Źródło:
Physicochemical Problems of Mineral Processing; 2017, 53, 2; 1009-1022
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reduction of derivative pipeline effort in water turbine
Autorzy:
Flis, L.
Dobrociński, S.
Kiełczyński, W.
Powiązania:
https://bibliotekanauki.pl/articles/178848.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
obciążenia hydrostatyczne
rurociąg derywacyjny
wytężenie rurociągów
turbina wodna
MES (metoda elementów skończonych)
hydrostatic load
water turbine
derivative pipeline
pipeline effort
FEM
Opis:
The article presents an approach to evaluate and reduce the effort of the derivative pipeline in a water turbine of a hydroelectric power station in its vulnerable spots. Potential places of the biggest effort of the structure, as well as the coefficient of displacement and safety factor related to them were identified using FEM numerical method. Pipeline reinforcement was designed and made based on FEM analysis and non-destructive tests.
Źródło:
Studia Geotechnica et Mechanica; 2013, 35, 1; 93-108
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Three-port beam splitter based on a sandwiched grating with an improved aspect ratio
Autorzy:
Shu, W
Wang, B
Li, H
Li, W
Chen, L.
Lei, L.
Zhou, J.
Powiązania:
https://bibliotekanauki.pl/articles/174445.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
aspect ratio
sandwiched grating
three-port beam splitter
Opis:
In this paper, a fused-silica transmission grating used as a three-port beam splitter is designed by using the rigorous coupled-wave analysis, which is based on the sandwiched grating structure at the wavelength of 800 nm under normal incidence. Firstly, it is feasible to realize such a grating with the prescribed grating duty cycle and grating period. Next, high efficiency can be also achieved for both TE and TM polarizations. Moreover, the aspect ratio of the grating depth to the ridge width can be improved, which is significant for practical applications. At last, the three-port beam splitter is designed with a covering layer on the surface, which can extend its life service.
Źródło:
Optica Applicata; 2015, 45, 3; 279-284
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental study and numerical simulation on fly ash separation with different plate voltages in rotary triboelectrostatic separator
Autorzy:
Zhang, L.
Tao, Y.
Tao, D.
Zhang, W.
Yang, L.
Powiązania:
https://bibliotekanauki.pl/articles/110712.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
fly ash
rotary triboelectrostatic separator
plate voltage
numerical simulation
Opis:
As the main solid wastes of coal-fired power plants, fly ash particles with different electrical properties are usually recycled using triboelectrostatic separator. The purpose of this study was to investigate the effect of different plate voltages on the separation of fly ash in a rotary triboelectrostatic separator with experiments and numerical simulation. The maximum values of yield of ash products (48.30%), and decarbonisation rate (50.89%) and the minimum loss-on-ignition (6.61%) were obtained when the plate voltage was 24 kV in the separation experiments, while 55.98%, 59.46%, 5.80% were reached respectively when the plate voltage was 26 kV in the simulation. In general, experimental data were similar with numerical simulation. The turning points appeared around 25 kV due to the increasing mismatch in products, which resulted from the reinforced rebound phenomena, namely the charged particle rebound from the electrode plate with a larger reflection velocity, when the plate voltage increased from 18 to 28 kV. It was validated by the numerical simulation results.
Źródło:
Physicochemical Problems of Mineral Processing; 2018, 54, 3; 722-731
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A study of selected properties of rhenium sulphide dispersion
Autorzy:
Pawlak, D. W.
Parus, J. L.
Skwarek, E.
Janusz, W.
Powiązania:
https://bibliotekanauki.pl/articles/951830.pdf
Data publikacji:
2014
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
rhenium sulphide
particle size distribution
zeta potential
Opis:
Due to potential application of rhenium sulphide in medicine and industry, this study is focused on the properties of synthetic and commercial rhenium sulphide. The main reaction of rhenium sulphide preparation involves potassium perrhenate and sodium thiosulphate in the acidic environment giving a mixture of rhenium sulphide and sulphur. The next step is removing sulphur by its dissolution in ether. Stabilization by Povidone K-25 is needed to obtain rhenium sulphide dispersed with the grain size of 0.5–4 m. The extrapolated value of pHiep for synthesised rhenium sulphide is 2.3 whereas for commercial samples this value is lower than 2. For synthetic sample a dependence of zeta potential on the carrier electrolyte concentration is found. It is larger than that for the commercial sample, probably due to surface oxidation during synthesis or purification.
Źródło:
Physicochemical Problems of Mineral Processing; 2014, 50, 1; 387-397
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of cotton on several enzymatic activities of the petroleum contaminated soil. A laboratory experiment
Autorzy:
Jingyan, L.
Jianxiong, W.
Ying, H.
Xianyong, J.
Powiązania:
https://bibliotekanauki.pl/articles/208048.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
cotton
remediation
soil pollution
alkaline phosphatase
degradation of pollutants
enzymatic activities
petroleum-contaminated soil
petroleum-polluted soils
bawełna
rekultywacja
zanieczyszczenie gleby
fosfataza alkaliczna
degradacja zanieczyszczeń
aktywność enzymatyczna
gleba zanieczyszczona ropą naftową
Opis:
A laboratory experiment lasting for 90 days was conducted to examine the interaction between a remediation plant, Gossypium hirsutum, and the petroleum contaminated soil. Root indices and 9 various types of soil enzymatic activities in two separate groups were determined. Results showed that compared to the uncontaminated control, the growth of cotton roots was slightly strengthened at the pollution level of 1000 mg-kg-1, while seriously inhibited at the pollution level of 2000 mg-kg-1 and 4000 mg-kg-1. At the same pollution level, all studied soil enzymatic activities except alkaline phosphatase were markedly higher in the group with plants than in the group without plants which may indicate that the content of nutrients essential for plant growth as well as the activities of microorganisms capable of degrading contaminants were both enhanced in soils planted with cotton, therefore conducive to the increase of the overall fertility level and the degradation of pollutants in the petroleum contaminated soil.
Źródło:
Environment Protection Engineering; 2013, 39, 1; 163-182
0324-8828
Pojawia się w:
Environment Protection Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The change of volume of the lumbar vertebrae along with aging in asymptomatic population: a preliminary analysis
Autorzy:
Miękisiak, G,
Łątka, D.
Janusz, W.
Urbański, W.
Załuski, R.
Kubaszewski, Ł.
Powiązania:
https://bibliotekanauki.pl/articles/949741.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
kręgosłup lędźwiowy
morfometria
starzenie się
lumbar spine alignment
Voxel-based morphometry
aging
asymptomatic population
Opis:
Previous studies have demonstrated that, the length of the lumbar spine is decreasing with age. Despite considerable research based on sagittal measurements, little is known about the changes in the volume of vertebrae. The objective of this study was to evaluate the changes in the volume of either column of the spine with age. Materials and methods: Computed tomography scans of 62 asymptomatic subjects, performed for thoracolumbar trauma evaluation were used to create virtual 3D models. At least 10 patients were assigned to every decade of life from third to eight. We used a novel technique to measure the volume of anterior column (AC) and posterior column (PC) per each segment (a total of 310 segments). Midline sagittal images were used to measure disc height (DH) and vertebral body height (VH). Results: With age, both DH increases, whereas the VH decreases. The overall length of lumbar segment of the spine decreases with age. The volumetric measurements performed on same subjects showed that volume of both AC and PC does not change with age in females. In males, there is a weak but statistically significant correlation between AC volume and age and no change in the volume of PC. The ratio of PC:AC volume does not change with age in women, although it decreases slightly but significantly (in favor of AC) with age in males. Conclusions: The overall length of lumbar spine decreases with age. This process is not a result of mere changes in the volume of either AC or PC.
Źródło:
Acta of Bioengineering and Biomechanics; 2018, 20, 3; 25-30
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Quantum-inspired particle swarm optimization algorithm with performance evaluation of fused images
Autorzy:
Le, Z
Xinman, Z.
Xuebin, X
Dong, W.
Jie, L.
Yang, L.
Powiązania:
https://bibliotekanauki.pl/articles/174501.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
multifocus image fusion
quantum particle swarm optimization
perfect reconstruction
superior speed
Opis:
In order to improve and accelerate the speed of image integration, an optimal and intelligent method for multi-focus image fusion is presented in this paper. Based on particle swarm optimization and quantum theory, quantum particle swarm optimization (QPSO) intelligent search strategy is introduced in salience analysis of a contrast visual masking system, combined with the segmentation technique. The superiority of QPSO is quantum parallelism. It has stronger search ability and quicker convergence speed. When compared with other classical or novel fusion methods, several metrics for image definition are exploited to evaluate the performance of all the adopted methods objectively. Experiments are performed on both artificial multi-focus images and digital camera multi-focus images. The results show that QPSO algorithm is more efficient than non-subsampled contourlet transform, genetic algorithm, binary particle swarm optimization, etc. The simulation results demonstrate that QPSO is a satisfying image fusion method with high accuracy and high speed.
Źródło:
Optica Applicata; 2013, 43, 4; 679-691
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł

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