Informacja

Drogi użytkowniku, aplikacja do prawidłowego działania wymaga obsługi JavaScript. Proszę włącz obsługę JavaScript w Twojej przeglądarce.

Wyszukujesz frazę "Zhang, Y. J." wg kryterium: Autor


Tytuł:
Propagation of solitary wave in non-uniform fiber system with high-order nonlinear effects
Autorzy:
Xiao, Y.
Zhang, J.
Zhang, L.
Powiązania:
https://bibliotekanauki.pl/articles/173308.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
solitary wave
coupled higher-order nonlinear Schrödinger equation
high-order nonlinear effect
Opis:
The ultra-short pulse propagation in a non-uniform fiber system is investigated based on the variable coefficient coupled higher-order nonlinear Schrödinger equation with the dispersion gain and nonlinear gain terms. By using the ansatz method and the split-step Fourier method, we get the exact solitary wave solution, with which the transmission process of the solitary wave is studied. Furthermore we obtain the stability of the solitary wave under finite initial perturbations. The interaction between two neighboring solitary waves is also studied.
Źródło:
Optica Applicata; 2018, 48, 2; 273-284
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of performance level on lower limb kinematics during table tennis forehand loop
Autorzy:
Qian, J.
Zhang, Y.
Baker, J. S.
Gu, Y.
Powiązania:
https://bibliotekanauki.pl/articles/307434.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
strefa graniczna
łańcuch kinematyczny
sport
lower limb drive
contact area
stretch-shortening cycle
kinetic chain
Opis:
Understanding of biomechanics is important in performance development since each skill has a fundamental mechanical structure. The purpose of this study was to investigate differences in lower limb kinematics during table tennis forehand loop between superior players (SP) and intermediate players (IP). Thirteen male players as superior and thirteen as intermediate participated in this test. A VICON motion analysis system and a Novel Pedar insole plantar pressure measurement system were used to record kinematic and contact area data, respectively. Participants were asked to execute single forehand loop against topspin ball with maximal power. Key findings were that SP showed significantly larger hip flexion and knee external rotation at backward-end and larger hip internal rotation and extension at forward-end compared with IP. Contact areas at both events were larger for SP. In addition, SP showed significantly larger joints angular changing rate during forward swing at the ankle and hip. Results indicated that SP possessed better ability of using lower limb drive in forehand loop.
Źródło:
Acta of Bioengineering and Biomechanics; 2016, 18, 3; 149-155
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Transmission characteristics of 85Rb and 87Rb laser-induced dichroism atomic filters at 795 nm
Autorzy:
Peng, Y F
Zhang, W J
Powiązania:
https://bibliotekanauki.pl/articles/173843.pdf
Data publikacji:
2014
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
atomic filter
optical anisotropy
narrowband
rubidium
Opis:
The transmission characteristics for 85Rb and 87Rb laser-induced dichroism atomic filters operating on rubidium D1 lines (795 nm) transitions are analyzed. By means of semiclassical density matrix equations of motion, a three-level model for the transmission characteristics of the ground state laser-induced dichroism atomic filter is presented. Calculative results show that this filter, using two counterpropagating pump and probe beams, can obtain higher transmission, narrower bandwidth and larger tuning capability than that using two copropagating pump and probe beams; with the aid of counterpropagating pump, the 85Rb ground state laser-induced dichroism atomic filter can be more effective to achieve higher peak transmission (>34%) and larger tunability (>1 GHz) than the 87Rb ground state laser-induced dichroism atomic filter in the same operation parameters. This result may be helpful for improving peak transmission (14.6%) of Rb ground state laser-induced dichroism atomic filter reported (CERÈ A. et al., Opt. Lett. 34(7), 2009, pp. 1012–1014).
Źródło:
Optica Applicata; 2014, 44, 1; 55-67
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Contribution on fluid inclusion abundance to activation of quartz flotation
Autorzy:
Yuan, Y.
Zhang, L.
Guan, J.
Zhang, C.
Wu, J.
Chen, Z.
Powiązania:
https://bibliotekanauki.pl/articles/110067.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
recovery
flotation
mineralogy
fluid Inclusions
fluid inclusion abundance
Opis:
In this study, comparative experiments were conducted on the recovery of quartz using flotation with different fluid inclusion abundances. A large number of fluid inclusions with various sizes have been found in natural quartz. Micrographs, inductively coupled plasma, electron probe microanalysis, homogenization temperature, Raman spectra, zeta potentials, X-ray photoelectron spectroscopy, scanning electron microscope, and energy dispersive spectrometer were used to characterize the fluid inclusions and quartz, as well as the adsorption tests and single mineral flotation experiments to investigate its floatability. The results demonstrated that it was more likely for quartz with higher fluid inclusion abundance to connect with Fe3+ sufficiently to achieve a high level of flotation recovery, due to the powerful collecting ability by sodium dodecyl sulphonate to Fe3+. Furthermore, the mechanism indicated that the adsorption between quartz and Fe3+ was a process of chemisorption.
Źródło:
Physicochemical Problems of Mineral Processing; 2018, 54, 3; 981-991
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Focusing of linearly polarized helico-conical Lorentz beam with sine-azimuthal variation wavefront
Autorzy:
Bao, Y.
Lan, J.
Miao, Y.
Zhang, D.
Gao, X.
Powiązania:
https://bibliotekanauki.pl/articles/174305.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
Lorentz beam
focusing properties
optical vortex
Opis:
In this article a theoretical research is described into focusing of a linearly polarized helico-conical Lorentz beam with a sine-azimuthal variation wavefront. The simulation results show the vortex charge on the axis, which has an obvious modulation effect on the focal modes of the Lorenz beam under certain beam parameters and phase parameters. Both the phase parameter and the vortex charge are zero, the focal spot appears round. The focal spot is symmetric about y axis when the charge is 0 and the phase parameter is adjusted. And the focal evolution patterns vary remarkably under different beam parameters and the phase parameters. In the process of focus evolution, there appears some novel focal patterns, such as a circle, a “T”, a butterfly, a small running humanoid, a whale tail, a flower of four leaves, a serpentine, a goldfish, a Chinese knot and an octopus, which indicates that the focus mode of the optical vortex Lorentz beam can be altered by changing the phase parameters and vortex charge.
Źródło:
Optica Applicata; 2018, 48, 3; 373-387
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Flotation behavior of hard-to-separate and high-ash fine coal
Autorzy:
Xing, Y.
Gui, X.
Liu, J.
Cao, Y.
Zhang, Y.
Li, S.
Powiązania:
https://bibliotekanauki.pl/articles/110585.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
flotation behavior
fine coal
Fuerstenau upgrading curve
energy input
selectivity
Opis:
The flotation behavior of hard-to-separate and high-ash fine coal was investigated using conventional flotation with constant power input. A new flotation process, based on energy input and distribution, was designed to lower the ash content of concentrate. The results obtained using Fourier transform infrared (FTIR) analysis show that the coal samples have good floatability because of many hydrophobic and few hydrophilic functional groups. Under a constant power input, a large number of ash-forming materials floated into a froth product at the start of flotation. Based on the Fuerstenau upgrading curves, it was determined that the 0.25-0.074 mm size fraction range showed the worst selectivity when compared with 0.50-0.25 mm and -0.074 mm size fractions. The desired concentrate with an ash content of 13.98%, 27.59% of ash recovery, and 80.01% combustible matter recovery could be obtained by transferring the excess energy of the flotation-conditioning stage to the pre-conditioning stage and increasing the power input step-by-step in the flotation-conditioning stage at equal total energy consumption.
Źródło:
Physicochemical Problems of Mineral Processing; 2016, 52, 2; 703-717
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pre-concentration of vanadium-bearing mica from stone coal by roasting-flotation
Autorzy:
Tang, J.
Zhang, Y.
Bao, S.
Liu, C.
Powiązania:
https://bibliotekanauki.pl/articles/109373.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
roasting
flotation
vanadium bearing mica
stone coal
Opis:
In China, stone coal is an important source of vanadium. The use of roasting–floatation for the pre-concentration of vanadium bearing mica from vanadium bearing stone coal was investigated based on its mineralogical characteristics. The results showed that the vanadium occurred in mica minerals and the main gangue minerals were coal, calcite, and quartz. The pre-concentration process comprises three key steps: roasting, desliming, and flotation. The coal was completely removed by roasting at 700 °C for an hour. Slime was concentrated and the subsequent flotation pulp was improved by desliming. Calcite was removed by reverse flotation and mica was concentrated by positive floatation. During the process, the grade of V2O5 was increased from 0.71% to 1.14%, and 46.18% of the tailings were rejected. The leaching rate of vanadium was increased from 30.49% of raw ore to 69.15% of the concentrate which was an increase of about 40% at the same leaching process. This technique may promote the efficient utilization of stone coal resources.
Źródło:
Physicochemical Problems of Mineral Processing; 2017, 53, 1; 402-412
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical investigation of root canal irrigation adopting innovative needles with dimple and protrusion
Autorzy:
Li, P.
Zhang, D.
Xie, Y.
Lan, J.
Powiązania:
https://bibliotekanauki.pl/articles/307257.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
dimple
protrusion
innovative needles
numerical simulation
passive flow control methods
root canal irrigation
wychylenie zębów
symulacja komputerowa
kanał zębowy
Opis:
As important passive flow control methods, dimples and protrusions have been successfully implemented via geometric modifications to manipulate flow fields to get a desired flow parameters enhancement. In this research, two novel needles were proposed based on a prototype by means of the dimple and protrusion, and flow patterns within a root canal during final irrigation with these needles were numerically investigated. The calculation cases consistent with the clinically realistic irrigant flow rates, which are 0.02, 0.16 and 0.26 mL s–1 are marked as case A, B and C, respectively. The characteristic parameters to estimate irrigation efficiency, such as shearing effect, mean apical pressure, irrigation replacement and fluid agitation, were compared and the optimal geometry in every calculation case was obtained. As shown from the results, flow rates and needle geometries were the causes of irrigation parameters variations. The sum of shear stress, irrigation replacement and fluid agitation were equal in the low flow rate case A, however, the needle with a protrusion on its tip had advantages in the three irrigation characteristic parameters above in calculation case B, and the needle with a dimple on its tip had advantages in calculation case C. Furthermore, the needles proposed did not give rise to the risk of irrigant extrusion. These needles can be better choices at larger flow rates. Therefore, needle geometry optimizations utilizing passive flow control methods are worthy to be investigated in the root canal irrigation enhancement.
Źródło:
Acta of Bioengineering and Biomechanics; 2013, 15, 1; 43-50
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research on relationship between carbon dioxide emissions, imports, exports, and population in China
Autorzy:
Jin, Q.-Y.
Zhang, J.
Gao, Y.-Q.
Su, X.
Fu, Y.-S.
Powiązania:
https://bibliotekanauki.pl/articles/207318.pdf
Data publikacji:
2014
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
population statistics
carbon dioxide
global warming
carbon dioxide emissions
total carbon
statystyki ludności
dwutlenek węgla
globalne ocieplenie
emisja dwutlenku węgla
węgiel całkowity
Opis:
Empirical relationships between carbon dioxide emission, imports, exports, and population have been investigated. An empirical model with carbon dioxide emissions, structure and scale of import and exports, populations was built Using ridge regression analysis and observed data from 1985 to 2006 in China, we examined the relationship between each part of carbon dioxide emission and corresponding coefficients, including GIV (gross imports value), GXV (gross exports value), and P (populations). The results have shown that the increasing trend in TCOE (total carbon dioxide emissions) was determined by the exports, while its standard level is determined by population. Increasing the imports may reduce TCOE. Considering working to expand economy, the best ways for China to reduce TCOE are to introduce advanced technology and take actions to guarantee strict execution of cut-emission policy. Although the increasing imports also can reduce TCOE, it is not reasonable for the global cut-emission policy. To control population is not applicable as the immense population base, so government's publicity for low-carbon live is a necessary and feasible way to reduce carbon dioxide emission.
Źródło:
Environment Protection Engineering; 2014, 40, 2; 75-85
0324-8828
Pojawia się w:
Environment Protection Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pre-concentration of graphite and LiCoO2 in spent lithium-ion batteries using enhanced gravity concentrator
Autorzy:
Zhu, X,-N.
Tao, Y.-J.
He, Y.-Q.
Zhang, Y.
Sun, Q.-X.
Powiązania:
https://bibliotekanauki.pl/articles/109609.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
spent lithium-ion batteries
electrode material
resource utilization
pre-concentration
enhanced gravity concentrator
Opis:
The pre-concentration of electrode material of spent lithium-ion battery has great significance on the resource utilization and environmental protection. The feasibility of separation of graphite and LiCoO2 based on density difference using the enhanced gravity concentrator was verified in this paper. Combustion characteristics of LiCoO2 and graphite were used to propose a simple evaluation index of separation efficiency. Separation tests were carried out to specify the influence of operating parameters on the separation efficiency. Moreover, the effect of particle size on the separation performance was studied. Combustion characteristics results showed that mass loss of graphite was much greater than that of LiCoO2. Thus, mass loss were used to evaluate the purity of product. Effective separation of graphite and LiCoO2 was achieved by the enhanced centrifugal separator. Separation results showed that increasing centrifugal force decreased the overflow yield and increased the graphite content of the overflow stream. In addition, yield of overflow grew an increase in fluidization water pressure, while the purity of graphite in overflow decreased. The effect of particle size on the separation efficiency was also significant, the separation efficiency decreased with the decreasing of particle size.
Źródło:
Physicochemical Problems of Mineral Processing; 2018, 54, 2; 293-299
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Role of dissolved mineral species in quartz flotation and siderite solubility simulation
Autorzy:
Luo, X.
Wang, Y.
Ma, M.
Song, S.
Zhang, Y.
Deng, J.
Liu, J.
Powiązania:
https://bibliotekanauki.pl/articles/109459.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
quartz
solubility
siderite
calcium ion
temperature
flotation
Opis:
Quartz is, in most cases, the major gangue mineral found in the iron ores. Although it can be activated by calcium at strong alkaline pH, quartz nevertheless, reports to the concentrate with Fe when the iron ores contain siderite. It causes a poor concentrate grade and separation between quartz and iron minerals. The effect of siderite on reverse anionic flotation of quartz from hematite was studied in our previous investigations. In this work, the effect of siderite dissolution on the quartz recovery in the froth product and the effect of pH, ions and temperature on siderite dissolution were investigated. Microflotation, PHREEQC simulation, solution chemistry calculation and Fourier transform infrared spectroscopy (FTIR) measurements were conducted. It was observed that the dissolved species of siderite exhibited negative impact on quartz flotation. This influence became weak to some extent by either stripping the dissolved species or shortening dissolution time. Siderite was easily dissolved in the presence of calcium ion under strong alkaline conditions and its solubility increased with increasing the calcium ion concentrate and temperature. When the calcium ion was added as an activator of quartz under strong alkaline conditions (pH>9.96), calcium existed mainly in the CaCO3 precipitation form according to the solubility rule in the presence of siderite. This form could adsorb onto quartz surfaces and further the chemical reaction between starch and quartz was monitored by FTIR measurements. This study provides a further supplement for previous study. A potential strategy is suggested that finding a collector used at low temperature or flotation under neutral (or weak alkaline) medium is helpful to the reverse flotation of iron ores containing siderite.
Źródło:
Physicochemical Problems of Mineral Processing; 2017, 53, 2; 1241-1254
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Flotation behaviour and surface characteristic of anosovite in a sodium oleate solution
Autorzy:
Wang, Y.
Wen, S.
Zhang, J.
Wu, D.
Xian, Y.
Shen, H.
Powiązania:
https://bibliotekanauki.pl/articles/110766.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
anosovite
sodium oleate
flotation
adsorption
Opis:
Properties of anosovite in titanium slag, anosovite flotation response in a collector solution of sodium oleate, and adsorption behaviour of sodium oleate on the mineral surface were studied in the present work using XRD, Raman spectra, flotation tests, zeta potential analysis, FTIR and XPS. The results show that the anosovite crystal contains magnesium, and its chemical composition is Mg0.09Ti2.91O5. The chemical bonds on the anosovite surface mainly comprise Ti-O bonds. Micro-flotation tests indicate that anosovite has better floatability at a wide pH range and the recovery reaches 88% at pH=6, when the dosage of sodium oleate is only 4·10−6 mol/dm3. The point of zero charge of anosovite was determined near pH 3.2 by the zeta potential measurement. In the flotation process, chemical adsorption occurs between the carboxyl of sodium oleate and the titanium sites on the anosovite surface.
Źródło:
Physicochemical Problems of Mineral Processing; 2017, 53, 2; 714-723
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Feature extraction of molten pool for laser welding quality real-time inspection
Autorzy:
Zhang, J
Yin, H
Huang, H
Yang, R
Yang, J
Li, Y
Powiązania:
https://bibliotekanauki.pl/articles/173597.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
laser materials processing
process monitoring and control
image analysis
Opis:
This paper proposed an image feature extraction method for laser welding molten pool inspection based on cellular neural network. TC4 titanium alloy thin plates were welded by Nd:YAG pulsed laser. A coaxial machine vision system was designed to acquire molten pool images. An auxiliary lighting source was employed to improve the molten pool image quality. By analyzing molten pool images, the welding defects such as fenestration or insufficient depth were identified. These results can be used as a feedback signal for laser power control. Experimental results showed that the proposed method can be used to improve laser welding quality.
Źródło:
Optica Applicata; 2015, 45, 4; 523-533
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
One step purification of impurities in the leachate of weathered crust elution-deposited rare earth ores
Autorzy:
Zhou, F.
Feng, J.
Wang, Z.
Xu, Y.
Zhang, Z.
Chi, R.
Powiązania:
https://bibliotekanauki.pl/articles/110333.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
leachate
weathered crust
rare earth ore
leachate purification
precipitation
Opis:
It is necessary to control and reduce the high content of Al3+, Cu2+ and Pb2+ ions in the leachate of weathered crust elution-deposited rare earth ore to facilitate the rare earth recovery and the quality of rare earth products. Neither NH4HCO3 nor Na2S are suitable for removal of all impurity ions and meanwhile maintain high rare earth recovery. Conventionally, NH4HCO3 is firstly adopted to remove Al3+, and then Cu2+ and Pb2+ are removed by using Na2S. This two steps purification process is quite long and results in lots of complication in operation. In this paper, a one-step purification by using the compound of NH4HCO3 and Na2S was proposed to remove Al3+, Cu2+ and Pb2+. The results showed that after purification 89% Cu, 92% Pb and 74% Al were removed from the leachate solution by using 0.1 M compound of NH4HCO3/Na2S, while maintaining 89% rare earth. The optimal purification parameters were: volume ratio of NH4HCO3 to Na2S of 9:1, volume ratio of compound to leachate of 0.05:1, precipitation time of 30 min.
Źródło:
Physicochemical Problems of Mineral Processing; 2017, 53, 2; 1188-1199
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Enhancing light harvesting of organic solar cells by using hybrid microlenses
Autorzy:
Xiao, X
Zhang, Z
Xie, S
Liu, Y
Hu, D
Du, J
Powiązania:
https://bibliotekanauki.pl/articles/174313.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
organic solar cells
hybrid microlens
light harvesting
achromatization
Opis:
Organic solar cells have drawn intense attentions in recent years due to their inherent advantages. But the relatively low power conversion efficiency is the main obstacle in the way of organic solar cell commercialization. One of the main reasons that limit the power conversion efficiency is the mismatch between electrical transmission properties and light absorption properties in an organic active layer. In this work, a highly efficient light trapping scheme with a hybrid microlens array is proposed to resolve this contradiction. This structure can achieve broadband absorption enhancement in the spectrum of interest by chromatic aberration correction and hole parameter adjustment. And the light trapping element can be separated from cells to avoid direct contact with an organic layer that may cause electrical defects. Moreover, it is also compatible with low cost manufacturing technologies.
Źródło:
Optica Applicata; 2015, 45, 1; 89-100
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł

Ta witryna wykorzystuje pliki cookies do przechowywania informacji na Twoim komputerze. Pliki cookies stosujemy w celu świadczenia usług na najwyższym poziomie, w tym w sposób dostosowany do indywidualnych potrzeb. Korzystanie z witryny bez zmiany ustawień dotyczących cookies oznacza, że będą one zamieszczane w Twoim komputerze. W każdym momencie możesz dokonać zmiany ustawień dotyczących cookies