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Tytuł:
Lightning discharge density on the territory of Azerbaijan
Częstość wyładowań atmosferycznych na terytorium Azerbejdżanu
Autorzy:
Gashimov, A. M.
Khidirov, F. L.
Babayeva, A. R.
Powiązania:
https://bibliotekanauki.pl/articles/410551.pdf
Data publikacji:
2011
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
power transmission line
lightning discharge
lightning days
Opis:
Hydrometeorological information about lightning days and period of lightning days, on the supports of OVL 110, 220, 330 kV and high objects on the territory of the republic (on the radio-television tower and lighting conductors) on the basis of statistic material, a map of lightning strokes about constant lightning strokes on the territory of the republic during a year on the 1 km" surface was compiled. The drawn up map can be used in power engineering and other objects projecting.
Na podstawie statystycznych informacji meteorologicznych dotyczących liczby i częstości wyładowań atmosferycznych do elektroenergetycznych linii przesyłowych wysokiego napięcia oraz innych obiektów, takich jak maszty radiowo-telewizyjne, piorunochrony, odgromniki, została sporządzona roczna mapa gęstości wyładowań atmosferycznych na terytorium Azerbejdżanu w przeliczeniu na 1 km2. Wykreślona w ten sposób mapa może być wykorzystana w elektroenergetyce, jak i do innych celów.
Źródło:
Present Problems of Power System Control; 2011, 1; 89-96
2084-2201
Pojawia się w:
Present Problems of Power System Control
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Endurance of the wooden bridge reinforced by the dowel plates
Autorzy:
Dahoua, L.
Boymatov, F.
Powiązania:
https://bibliotekanauki.pl/articles/178939.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
road infrastructure
railway
fatigue
number of loads
Opis:
The most important piece of road infrastructure is bridges. Wooden bridges have advanced constantly during the past decades. The trend began in Scandinavian countries but has also now gained significant ground in Russia. This research studies experimental endurance potential of the joints of the wooden beam while considering the coefficient of asymmetry of the cycle, which corresponds to the actual operating conditions. Performance analysis of the composite bars is carried out based on the experiment; the development of a special methodology for calculating the joints of wooden elements with the dowel plates for their better endurance is also introduced in this paper. The results of experimental studies on the performance of bending composite wooden bridge bars based on dowel plates operating under cyclic influences thus determine the endurance limit of wood for composite wooden bridge beams based on dowel plates. The calculation technique and interdependence of the endurance coefficient affecting the asymmetry coefficient of the bent composite wooden bridge bars on the dowel plates under cyclic loading are considered. The experimental data on the endurance of composite wooden bridge beams have been obtained, and separate analysis has been made of the compounds under cyclic loading performance; a method has been developed for calculating the bent composite wooden bridge bars reinforced by the dowel plates under cyclic influences.
Źródło:
Studia Geotechnica et Mechanica; 2018, 40, 3; 202-207
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The influence of aging on the isometric torque sharing patterns among the plantar flexor muscles
Autorzy:
Oliveira, L. F.
Verneque, D.
Menegaldo, L. L.
Powiązania:
https://bibliotekanauki.pl/articles/306726.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
starzenie się
EMG
zgięcie podeszwowe
mięsień trójgłowy łydki
aging
triceps surae
plantar flexion
torque sharing
Opis:
Purpose: Physiological cross-sectional area (PCSA) reduction of the triceps surae (TS) muscles during aging suggests a proportional loss of torque among its components: soleus, medial and lateral gastrocnemii. However, direct measurements of muscle forces in vivo are not feasible. The purpose of this paper was to compare, between older and young women, isometric ankle joint torque sharing patterns among TS muscles and tibialis anterior (TA). Methods: An EMG-driven model was used for estimating individual muscle torque contributions to the total plantar flexor torque, during sustained contractions of 10% and 40% of maximum voluntary contraction (MVC). Results: Relative individual muscle contributions to the total plantar flexion torque were similar between older and young women groups, for both intensities, increasing from LG, MG to SOL. Muscle strength (muscle torque/body mass) was significantly greater for all TS components in 40% MVC contractions. Increased TA activation was observed in 10% of MVC for older people. Conclusions: Despite the reduced maximum isometric torque and muscle strength, the results suggest small variations of ankle muscle synergies during the aging process.
Źródło:
Acta of Bioengineering and Biomechanics; 2017, 19, 1; 41-45
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Use of ultrafiltration and nanofiltration processes for the elimination of three selected emerging contaminants: amitriptyline hydrochloride, methyl salicylate and 2-phenoxyethanol
Autorzy:
Benítez, F. J.
Real, F. J.
Acero, J. L.
Casas, F.
Powiązania:
https://bibliotekanauki.pl/articles/207379.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
COD
municipal wastewater treatment plants
water quality
filtration process
ChzT
miejskie oczyszczalnie ścieków
jakość wody
proces filtracji
Opis:
Three emerging contaminants: amitriptyline hydrochloride (AH), methyl salicylate (MS) and 2-phenoxyethanol (PE) were treated by means of filtration processes for their elimination from ultrapure (UP) water in a first stage, and from three water matrices (surface water from a reservoir, and two effluents from two municipal wastewater treatment plants) in a second stage. For this purpose, ultrafiltration and nanofiltration membranes were used in a cross-flow laboratory equipment. The permeate fluxes at the steady state were determined, and the resistances to the permeate flux were established. It was found that the inherent resistance of the clean membranes provided a much larger resistance than the fouling resistance. The retention coefficients for each individual contaminant were evaluated, as well as the retention coefficients referred to three water quality parameters: absorbance at 254 nm, COD and TOC. These parameters provide the effectiveness of the filtration processes for the elimination of the organic matter present in the selected water matrices.
Źródło:
Environment Protection Engineering; 2017, 43, 3; 125-141
0324-8828
Pojawia się w:
Environment Protection Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental study on electrokinetic of kaolinite particles in aqueous suspensions
Autorzy:
Min, F.
Zhao, Q.
Liu, L.
Powiązania:
https://bibliotekanauki.pl/articles/110918.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
kaolinite
zeta potential
pH
immersion time
electrophoresis
Opis:
Influence of aqueous phase properties and process parameters on kaolinite particle zeta potential was quantified by electrophoresis experiments. The results indicated that pH strongly altered the zeta potential of kaolinite and it decreases at the beginning and then increases in the range of pH = 2–13. The activity of different cations changes the zeta potential and has the following tendency of Al3+ > Ca2+ > Mg2+ > Na+ and the zeta potential increases due to heterocoagulation of different mineral particles in suspension. It was found that the zeta potential of kaolinite particles increases after the suspension was stirred and decreases at the beginning, and then increases with soaking time. The FTIR results showed that the zeta potential takes into account ion adsorption and the change of Si–O, Al–O and Al–OH groups on the surface of the kaolinite particles.
Źródło:
Physicochemical Problems of Mineral Processing; 2013, 49, 2; 659-672
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of spodumene leaching with sodium hydroxide on its flotation
Autorzy:
Yu, F.
Wang, Y.
Zhang, L.
Powiązania:
https://bibliotekanauki.pl/articles/110505.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
spodumene
flotation
preferential leaching
XPS analysis
Opis:
Effects of NaOH on flotation of spodumene, quartz and feldspar using oleic acid as a collector were investigated through microflotation and bench scale flotation tests. It was determined that NaOH acted more than a pH regulator in the tests. The X-ray photoelectron spectroscopy revealed that spodumene was preferentially leached by conditioning with high concentration of NaOH in the solution and exposed more Li positive sites on the mineral surface leading to an improved flotation.
Źródło:
Physicochemical Problems of Mineral Processing; 2015, 51, 2; 745-754
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Does water lubrication affect friction differently for rocks and soils? Evidence and open questions
Autorzy:
Cafaro, F.
Hamad, A.
Monterisi, L.
Powiązania:
https://bibliotekanauki.pl/articles/2172879.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
water lubrication
friction scale
fracture
sliding
roughness
Opis:
The present paper focuses on the shear strength exhibited by rocks and soils when sliding along dry and wet surfaces, with this mechanism of failure being strongly related to the water lubrication phenomenon. It is well known that the frictional behaviour of geomaterials requires multiscale investigation. Under this perspective, experimental evidence of both friction at the grain scale (i.e. interparticle friction) and friction along sliding surfaces of rock and granular soil samples (i.e. surface friction) are analysed by using data from the literature. The review is addressed at linking different scales, stating the differences between rocks and soils in terms of frictional response to sliding and trying to point out still open problems for the research.
Źródło:
Studia Geotechnica et Mechanica; 2022, 44, 3; 211--223
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Technical and Economical Evaluation of Proton Exchange Merobrane (PEM) Fuel Cell for Commercial Applications
Autorzy:
Katyara, S.
Iżykowski, J
Staszewski, Ł
Shaikh, F.
Powiązania:
https://bibliotekanauki.pl/articles/410535.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
Proton Exchange Membrane
PEM
Fuel Cell
DC/DC boost converter
Distributed Generation
DG
polarization curve
efficiency
Opis:
The green energy sources are the utmost needs of today’s world where the reserves of fossil fuel are depleting day by day. The Distributed Generation (DG) has become integral part of power system at commercial level. The most efficient among all DGs and Renewable Energy Sources (RES) is the Fuel Cell (FC) power generation. The fuel cell invariably converts chemical energy directly into electricity. The Fuel cells have normally 60 to 70% efficiency at working conditions. The polarization curve of fuel cell plays important role in improving its efficiency. This research presents the mathematical and Simulink modeling 6 kW, 45 Vdc of Proton Exchange Membrane (PEM) fuel cell. The input thermodynamic parameters of fuel cell are varied and their effects on the output electrical variable are observed. The DC/DC boost converter is used to step up the voltage of fuel cell to 100 Vdc at commercial usable level. A new mathematical equation is presented to improve the efficiency of fuel. The mathematical results are then varied through Simulink results.
Źródło:
Present Problems of Power System Control; 2017, 8; 41-49
2084-2201
Pojawia się w:
Present Problems of Power System Control
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnesium silicate conjugated with calcium lignosulfonate: In situ synthesis and comprehensive physicochemical evaluations
Autorzy:
Klapiszewski, Ł.
Zietek, J.
Ciesielczyk, F.
Siwinska-Stefanska, K.
Jesionowski, T.
Powiązania:
https://bibliotekanauki.pl/articles/109651.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
biopolymers
hybrid materials
synthetic magnesium silicate
calcium lignosulfonate
in situ sol-gel route
Opis:
The aim of this study was to effectively combine synthetic magnesium silicate with the lignin-derived biopolymer calcium lignosulfonate, using the in situ sol-gel route. Magnesium ethoxide and tetraethoxysilane were used as precursors of MgO and SiO2. The synthesis was carried out in alcoholic solution with the addition of ammonia solution as a promoter of hydrolysis. Calcium lignosulfonate was introduced to the reaction medium prior to the synthesis of magnesium silicate. The resulting hybrid powder material was thoroughly characterized, including morphology and particle sizes (SEM microscopy and the DLS technique), porous structure parameters (the BET method and BJH model), thermal stability (TG analysis) and electrokinetic stability (LDV measurements). FTIR spectral analysis was carried out to confirm the effectiveness of the proposed synthesis methodology. Based on the results, a mechanism is proposed for the MgSiO3/lignosulfonate interactions. The resulting novel type of hybrid material combines the multifunctional nature of the biopolymer (diversity of functional groups) with the well-developed porous structure of synthetic magnesium silicate. Its physicochemical parameters were found to depend significantly on the quantity of lignosulfonate used in the synthesis.
Źródło:
Physicochemical Problems of Mineral Processing; 2018, 54, 3; 793-802
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A longitudinal assessment of myoelectric activity, postural sway, and low-back pain during pregnancy
Autorzy:
Moreira, L. S.
Elias, L. A.
Gomide, A. B.
Vieira, M. F.
Do Amaral, W. N.
Powiązania:
https://bibliotekanauki.pl/articles/307463.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
elektromiografia
stabilność postawy
bóle kręgosłupa
electromyography
low back pain
postural balance
pregnancy trimesters
stabilometry
Opis:
The present study aimed at investigating the control of upright quiet standing in pregnant women throughout pregnancy, and whether low-back pain exerts influence on this motor task. Methods: Myoelectric signals from postural muscles and stabilometric data were collected from 15 non-pregnant and 15 pregnant women during upright quiet standing. Electromyogram envelopes and center of pressure metrics were evaluated in the control group, as well as in pregnant women in their first and third trimester of pregnancy. A correlation analysis was performed between the measured variables and a low-back pain disability index. Results: Pregnant women exhibited a decreased maximum voluntary isometric activity for all postural muscles evaluated. Additionally, the activity of lumbar muscles during the postural task was significantly higher in the pregnant women in comparison to the non-pregnant controls. The soleus muscle maintained its activity at the same level as the gestation progressed. Higher postural oscillations were observed in the anteroposterior direction while mediolateral sway was reduced in the third trimester of pregnancy. No correlation was detected between the lowback pain disability index and neuromechanical variables. Conclusion: This study provides additional data regarding the functioning and adaptations of the postural control system during pregnancy. Also, we provide further evidence that postural control during quiet standing cannot be used to predict the occurrence of low-back pain. We hypothesize that the modifications in the neural drive to the muscles, as well as in postural sway may be related to changes in the biomechanics and hormonal levels experienced by the pregnant women.
Źródło:
Acta of Bioengineering and Biomechanics; 2017, 19, 3; 77-83
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Enhancing SO2 removal efficiency by lime modified with sewage sludge in a novel integrated desulfurization process
Autorzy:
Qin, L.
Han, J.
Chen, W.
Liu, Z.
He, M.
Xing, F.
Powiązania:
https://bibliotekanauki.pl/articles/950037.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
sewage sludge
steel industry
sintering process
osad ściekowy
przemysł hutniczy
proces spiekania
Opis:
In China, the sintering process annually emitted around 1.5 million t SO2, representing 70% of SO2 produced from the iron and steel industry. Lime based sorbent was modified with municipal sewage sludge (MSS) and the influence of the modification on the desulfurization efficiency was investigated in a laboratory-scale novel integrated desulfurization (NID) reactor. The properties of modified sorbent were characterized by the Brunauer–Emmett–Teller (BET) analyzer and X-ray fluorescence (XRD) analyzer. BET surface area was increased from 17.48 to 46.68 m2g–1. when the MSS/lime ratio increased from 0 to 0.08. Ca4Al8Si8O32, Ca1.5SiO3.5, Na2Si2O5 and CaSiO3 found in the modified lime benefited for the increase of the BET surface area and pore volume. The effects of sewage sludge/CaO weight ratio, calcination temperature and hydration time on the desulfurization efficiency were also studied. SO2 removal efficiency was increased from 88.7% to 97.3% after using the lime modified with sewage sludge.
Źródło:
Environment Protection Engineering; 2017, 43, 4; 17-27
0324-8828
Pojawia się w:
Environment Protection Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analog-based duobinary-4-PAM for electrical bandwidth limited optical fiber links
Autorzy:
Suhr, L.F.
Madsen, P.
Monroy, I. T.
Olmos, J. J. V.
Powiązania:
https://bibliotekanauki.pl/articles/173933.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
optical communications
advanced modulation formats
multilevel modulation
Opis:
This paper presents a demonstration of a seven level duobinary-4-PAM signal operating at 10.16 Gbit/s. The polybinary generation is achieved by a simple electrical Bessel filter of 5th order, with a frequency cut-off of 1.8 GHz. We assess the impact of the filter placement, either at the transmitter or the receiver, and find the impact is minimal in terms of bit error rate performance in transmissions of up to 40 km of single mode fiber.
Źródło:
Optica Applicata; 2016, 46, 1; 71-78
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnified holographic projection based on spatial light modulators
Autorzy:
Su, Y.
Cai, Z.
Shi, L.
Zhou, F.
Chen, H.
Wu, J.
Powiązania:
https://bibliotekanauki.pl/articles/174247.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
holographic display
spatial light modulators
computer-generated holograms
magnified holographic projection
Opis:
In this paper, a magnified holographic projection based on spatial light modulators is proposed and implemented by combining four magnification methods, including similarity principle of Fourier transform, spatial division, digital lens, and image splicing methods. The Fourier holographic display system is constructed for the experimental verification of the proposed methods. With such four methods of holographic magnification, the reconstruction image can be magnified to 10 × 5 times in two-dimensional directions, which is verified by the experiments. Furthermore, the undesirable light of holographic projection is eliminated by encoding the linear phase onto the computer-generated holograms. The experimental results prove that the proposed system can realize magnified holographic projection with good reconstructed quality, which provides a promising potential for the dynamic holographic projector.
Źródło:
Optica Applicata; 2018, 48, 4; 589-600
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of calcination parameters on physicochemical and structural properties of co-precipitated magnesium silicate
Autorzy:
Ciesielczyk, F.
Bartczak, P.
Klapiszewski, L.
Paukszta, D.
Piasecki, A.
Jesionowski, T.
Powiązania:
https://bibliotekanauki.pl/articles/110710.pdf
Data publikacji:
2014
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
magnesium silicate
precipitation
calcination
WAXS
porous structure
Opis:
Physicochemical properties of different oxide systems depend mostly on the method of their preparation and classification, so the main aim of the study was to obtain the MgO·SiO2 hybrid in an aqueous solution and its calcination under assumed conditions. Research scope included evaluation of the effect of the basic parameters of the calcination process (time and temperature) on the structural properties of the final materials. Products obtained by the proposed method were thoroughly characterized. The chemical composition, crystalline structure, morphology and nature of the dispersion as well as parameters of the porous structure were established. The results of research in a decisive manner confirmed the possibility of designing the properties of inorganic oxide systems such as MgO·SiO2, which will definitively scheduled into potential directions for their use.
Źródło:
Physicochemical Problems of Mineral Processing; 2014, 50, 1; 119-129
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Efficient sulfidization of lead oxide at high temperature using pyrite as vulcanizing reagent
Autorzy:
Zheng, Y.-X.
Lv, J.-F.
Wang, H.
Wen, S.-M.
Huang, L.
Powiązania:
https://bibliotekanauki.pl/articles/110351.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
lead oxide
sulfidization roasting
pyrite
reaction mechanism
TG
Opis:
A sulfidization roasting-flotation process was usually viewed to be effective in treating the refractory oxide ore. In this paper, pyrite was proposed to be applied as a potential vulcanizing reagent to transform PbO or its surface to PbS based on feasibilities of technology and economy. The evolution process, phase and characteristics of crystal growth were investigated by TG, XRD and SEM-EDS, respectively, to interpret the interaction mechanism of lead oxide and pyrite at high temperature. It was found that the decomposition process of pyrite under argon atmosphere was a slow process of sulfur released from FeS2 to FexS, which made the process easier to be controlled. When PbO was introduced into the system, the initial solid-solid (PbO-FeS2) reaction and prevailing solid-gas (PbO-S2(g)) reaction occurred at about 500 °C and 700 °C, respectively. Combined with the SEM-EDS analyses results, the optimal temperature for the sulfidization of PbO should be in the range of 700-750 °C.
Źródło:
Physicochemical Problems of Mineral Processing; 2018, 54, 2; 270-277
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł

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