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Tytuł:
An approach to suppress low-frequency oscillation in the hybrid multi-Infeed HVDC of mixed H2/H∞ robust-based control theory
Autorzy:
Li, Congshan
Liu, Yan
Li, Yikai
He, Ping
Fang, Yan
Sheng, Tingyu
Powiązania:
https://bibliotekanauki.pl/articles/2042784.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
additional damping controller
CSP
HMIDC
LFO
mixed 2/∞ control
TLS-ESPRIT
Opis:
A hybrid multi-infeed HVDC (HMIDC) system is composed of line-commutated converter-based high-voltage direct current (LCC-HVDC) and voltage-source converterbased high-voltage direct current (VSC-HVDC), whose receiving ends have electrical coupling. To solve the problem of low-frequency oscillation (LFO) caused by insufficient damping in the HMIDC system, according to the multi-objective mixed 2/∞ output feedback control theory with regional pole assignment, an additional robust damping controller is designed in this paper, which not only has good robustness, but also has strong adaptability to the change of system operation mode. In the paper, the related oscillation modes and transfer function of the controlled plant are obtained, which are identified by the total least squares estimation of signal parameters via rotary invariance technology (TLS-ESPRIT). In addition, the control-sensitive point (CSP) for suppressing LFO based on the small disturbance test method is determined, which is suitable for determining the installation position of the controller. The results show that the control sensitivity factor of VSC-HVDC is greater than that of LCC-HVDC so that adding an additional damping controller to VSC-HVDC is better than LCC-HVDC in suppressing the LFO of HMIDC. Finally, a hybrid double infeed DC transmission system with three receiving terminals is built on PSCAD/EMTDC where the time-domain simulations are performed to verify the correctness of the CSP selection and the effectiveness of the controller.
Źródło:
Archives of Electrical Engineering; 2022, 71, 1; 109-124
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research on influencing factors of emergency power support for voltage source converter-based multi-terminal high-voltage direct current transmission system
Autorzy:
Li, Congshan
Zhen, Zikai
Sheng, Tingyu
Liu, Yan
Zhong, Pu
Zhang, Xiaowei
Powiązania:
https://bibliotekanauki.pl/articles/2172797.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
coordinated control
emergency DC power support
influencing factors
VSC- MTDC transmission
Opis:
Voltage source converter-based multi-terminal high-voltage direct current (VSCMTDC) transmission system can realize a multi-point power supply, multi-drop power receiving, and mutual coordination between the converter stations to ensure the reliability of the transmission. Based on the PSCAD/EMTDC platform, a five-terminal DC transmission system model is established. According to the fast power regulation capability and overload capacity of theVSC-MTDC power transmission system, an analysis of additional emergency power support for a transmission system under large disturbance conditions was carried out. A new control strategy for emergency power support that introduces its basic principle is proposed in this paper. It uses the short-term overload capability of the DC system. By changing the power reserve of the converter station and the electrical distance between the converter stations, the influence of the power reserve and the electrical distance on the emergency power supply guarantee is analyzed the stability of the system is improved, thereby improving the sudden change of power caused by voltage fluctuations, and the feasibility of the control module is verified by PSCAD simulation. The simulation results show that when the system power supply suddenly changes, the converter stations at a short distance and large power reserve has a better effect on emergency power supply protection. A comparative study of the active power support of a single converter station and multiple converter stations is carried out. The research results show that the use of emergency power support in the DC transmission system has a good effect on maintaining the stability of the inter-connection system and the reliability of the power supply.
Źródło:
Archives of Electrical Engineering; 2022, 71, 4; 881--894
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modulation Mechanism of Acoustic Scattering in Underwater Corner Reflectors with Acoustic Metasurfaces
Autorzy:
Du, Jiaman
Peng, Zilong
Ge, Lili
Lyu, Shijin
Zhou, Fulin
Liu, Yan
Powiązania:
https://bibliotekanauki.pl/articles/31339794.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
acoustic scattering
metasurface
ray tracing
corner reflector
virtual source method
Opis:
Using the tunderwater corner reflector (CR) to simulate the acoustic scattering characteristics of the military target is a new technology to counter active sonar detection. Existing underwater CRs only have the ability to interfere with the acoustic field, but have limitations in acoustic wave modulation. Therefore, acoustic metasurfaces applied on CRs to enhance the ability of acoustic wave modulation has a great application prospect. A fast prediction method based on the Kirchhoff approximation (KA) and the ray tracing theory is proposed to calculate the acoustic scattering characteristics of CR with acoustic metasurfaces in grooves array type. The accuracy of the method is verified by the finite element method (FEM) simulation. The modulation effect of CR with grooves array in different gradient combinations on the structural scattering acoustic field is analyzed. The research shows that the CR with different combinations of the acoustic metasurface has an obvious modulation effect on the amplitude of the acoustic waves and the deflection of acoustic field. In particular, the grooves array in combination with positive and negative gradients has an obvious deflection impact on the scattering acoustic field.
Źródło:
Archives of Acoustics; 2023, 48, 4; 465-473
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Prediction of the Crystalline Densities of Aliphatic Nitrates by Quantum Chemistry Methods
Autorzy:
Wang, Guixiang
Xu, Yimin
Xue, Chuang
Ding, Zhiyuan
Liu, Yan
Liu, Hui
Gong, Xuedong
Powiązania:
https://bibliotekanauki.pl/articles/358531.pdf
Data publikacji:
2019
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
aliphatic nitrate
density
quantum chemistry
correlation
Opis:
Crystal density is a basic and important parameter for predicting the detonation performance of explosives, and nitrate esters are a type of compound widely used in the military context. In this study, thirty-one aliphatic nitrates were investigated using the density functional theory method (B3LYP) in combination with six basis sets (3-21G, 6-31G, 6-31G*, 6-31G**, 6-311G* and 6-31+G**) and the semiempirical molecular orbital method (PM3). Based on the geometric optimizations at various theoretical levels, the molecular volumes and densities were calculated. Compared with the available experimental data, the densities calculated by various methods are all overestimated, and the errors of the PM3 and B3LYP/3-21G methods are larger than those of other methods. Considering the results and the computer resources required by the calculations, the B3LYP/6-31G* method is recommended for predicting the crystalline densities of organic nitrates using a fitting equation. The results obtained with this method are slightly better than those reported by Keshavarz and Rice. In addition, the effects of various groups (such as –ONO2, –OH, –Cl, –O–, and –CH2–) on the densities are also discussed, which is helpful for the design of new molecules in terms of practical requirements.
Źródło:
Central European Journal of Energetic Materials; 2019, 16, 3; 412-432
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evaluation of Stab Resistance of Coated UHMWPE Fabric
Ocena odporności na przebicie powlekanej tkaniny z włókien polietylenowych o ultra wysokiej masie cząsteczkowej (UHMWPE)
Autorzy:
Yang, Wan-Qiu
Liu, Xiao-Yan
Yu, Yan-Ping
Yu, Wei-Dong
Powiązania:
https://bibliotekanauki.pl/articles/231896.pdf
Data publikacji:
2020
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Biopolimerów i Włókien Chemicznych
Tematy:
stab resistance
fabric
hard particles
coating
odporność na przebicie
tkanina
twarde cząstki
powłoka
Opis:
In recent years, individual protection has attracted much attention in the area of personal safety, especially stab resistant clothing. Nowadays, fabrics of high performance fibre are often used in stab-resistant clothing. Therefore, in this paper ultra-high molecular weight polyethylene(UHMWPE) fibre fabrics were used to explore their distribution of boron carbide(B4C) particles. The effect of different processing techniques on stab resistance was discussed. Finally, it was found that when the particle dimension was 5 microns, the coating thickness 100 microns, the coating temperature 64 °C and the particle and binder ratio 2:3, the stab-resistance performance of the fabrics was best. The stab resistance of multi-layer fabrics was also discussed, and it was found that the relationship between energy absorber and the number of layers was changed by hard particles.
W ostatnich latach ochrona indywidualna przyciągnęła wiele uwagi w zakresie bezpieczeństwa osobistego, zwłaszcza w przypadku odzieży odpornej na przebicie. W dzisiejszych czasach tkaniny z wysokowydajnych włókien są często stosowane w odzieży odpornej na przebicie. Dlatego w artykule wykorzystano tkaniny z włókien polietylenowych o ultra wysokiej masie cząsteczkowej (UHMWPE) do zbadania ich rozkładu cząstek węglika boru (B4C). Omówiono wpływ różnych technik przetwarzania na odporność na przebicie. Stwierdzono, że w przypadku wymiaru cząstek równemu 5 mikronom, grubości powłoki 100 mikronów, temperaturze powlekania 64 °C i stosunku cząstek i spoiwa 2:3, odporność na przebicie tkanin była najlepsza. Omówiono również odporność na przebicie tkanin wielowarstwowych i stwierdzono, że zależność między pochłoniętą energią a liczbą warstw uległa zmianie przez twarde cząstki.
Źródło:
Fibres & Textiles in Eastern Europe; 2020, 2 (140); 76-79
1230-3666
2300-7354
Pojawia się w:
Fibres & Textiles in Eastern Europe
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Interception of a hypersonic vehicle by low-speed interceptors: novel perspectives and cost optimisation
Autorzy:
Liu, Shuangxi
Liu, Shijun
Yan, Binbin
Zhang, Tong
Zhang, Xu
Yan, Jie
Powiązania:
https://bibliotekanauki.pl/articles/2173726.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
small speed ratio
hypersonic vehicle
interception performance
boundary conditions
współczynnik prędkości mały
pojazd hipersoniczny
wydajność przechwytywania
warunki brzegowe
Opis:
The conditions for accurately intercepting hypersonic vehicles by low-speed interceptors in the terminal guidance process are examined, considering the general form of a guidance scheme. First, based on the concept of the engagement geometry, three interception scenarios are established considering different manoeuvring configurations of the interceptors and hypersonic vehicle. Second, the boundary conditions for intercepting hypersonic vehicles (with speeds higher than those of the interceptors) are specified for the three scenarios, considering several factors: the speed, path angle, line-of-sight angle, and available overload of the interceptor; path angle and manoeuvrability of the hypersonic vehicle; and relative distance between the interceptor and vehicle. A series of simulations are performed to clarify the influence of each factor on the interception performance in the three interception scenarios. The challenges associated with accurately intercepting hypersonic vehicles by low-speed interceptors are summarised, and several recommendations for designing guidance laws are presented.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2022, 70, 6; art. no. e143537
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Activating flotation of chalcopyrite using CuSO4 and H2O2 from the cyanide tailings
Autorzy:
Ai, G.
Yan, H.
Qiu, T.
Liu, C.
Powiązania:
https://bibliotekanauki.pl/articles/109562.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
cyanide tailings
chalcopyrite
CuSO4
H2O2
activation mechanism
Opis:
The effects of CuSO4 and H2O2 on the flotation behavior of cyanide chalcopyrite were investigated by flotation tests, microcalorimetry and X-ray photoelectron spectroscopy (XPS). The underlying activation mechanism was studied in the perspective of micro-thermodynamics and surface properties. The flotation results indicated that cyanide chalcopyrite was strongly inhibited by sodium cyanide, with the maximum flotation recovery of 22.5% only. CuSO4 and H2O2 significantly improved the flotation of cyanide chalcopyrite, and the flotation recovery was increased to 92.28% and 84.35%, respectively. The micro-thermodynamics results indicated that the adsorption heat of butyl xanthate on cyanide chalcopyrite surface increased after the addition of CuSO4 and H2O2, as well as the reaction order. CuSO4 and H2O2 can significantly improve the adsorption of butyl xanthate on the surface of cyanide chalcopyrite by decreasing the apparent activation energy by 80.11% and 66.54%, respectively. XPS analysis indicated that the CuCN was generated on the surface of cyanide chalcopyrite, leading to the loss of sulfur and inhibiting the adsorption of collectors. As a result, the flotation of cyanide chalcopyrite was depressed. It is considered that, CuSO4 and H2O2 can improve the flotation of cyanide chalcopyrite by eleminating CuCN from its surface and increasing the concentration of S by 57.02% and 37.48%, respectively.
Źródło:
Physicochemical Problems of Mineral Processing; 2018, 54, 2; 578-589
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influences of process water chemistry on reverse flotation selectivity of iron oxides
Autorzy:
Tang, Min
Wang, Dong
Wu, Yan
Liu, Dianwen
Powiązania:
https://bibliotekanauki.pl/articles/2175429.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
water chemistry
ion distribution
iron oxides
reverse flotation
Opis:
It is critical for water quality in flotation as it dramatically influences the chemical/electrochemical properties of mineral surfaces and their interactions with reagents. Many potential variations could alter the water chemistry: water recirculation, mineral dissolutions, reagent additions, etc. This study aimed to identify the key elements from the recycled water sources affecting the separation efficiency in a typical industrial flotation circuit of iron oxides through a series of bench/micro flotation tests, zeta potential measurement, etc. The built-up and distribution of the dominant cations/anions in the process water from the roughers in the flotation system was also analyzed and recorded by Inductively Coupled Plasma-Optical Emission (ICP-OES) for a period of about three months when the operations were stable. The flotation results pointed out that a concentrate with a sharp increase of 6.0% Fe recovery and 2.5% SiO2 content was obtained by using the recycled tailing water only in comparison by using fresh water. In contrast, a slight uptrend in the grade of Fe but a substantial loss of near 6.5% Fe recovery occurs by using the treated sewage water alone instead. This could attribute to the ion distributions in these water sources, in which Ca2+, Fen+, Mg2+ or SO42ions were determined as the key ions influencing the flotation behaviors of the iron ore. But the competitive effects of Fe3+ ions were more significant than the ones of Ca2+ or Mg2+ ions. And the occurrence of starch could deteriorate the dilution of silicates in concentration induced by Fe3+/Fe2+ ions. It can be explained by zeta potential measurement or solution chemistry of those ions, indicating that at 8.5-9.0, the coating of the precipitates of Fe(OH)3(s) induced by iron ions alters a reverse on the zeta potentials of quartz. The presence of SO42-ions, however, has a positive role in reducing the possibility of slime coating on silicates due to acting as a chelating agent of iron ions.
Źródło:
Physicochemical Problems of Mineral Processing; 2022, 58, 6; art. no. 151839
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Cortical Localization of α- and γ-Tubulin and the Assembly of Cortical Microtubule Cytoskeleton in Hypotrichous Ciliate Euplotes eurystomus
Autorzy:
Sheng, Xin
Sheng, Yan
Liu, Yuehua
Wang, Junhua
Powiązania:
https://bibliotekanauki.pl/articles/52393951.pdf
Data publikacji:
2017
Wydawca:
Uniwersytet Jagielloński. Wydawnictwo Uniwersytetu Jagiellońskiego
Tematy:
basal body
ciliature microtubular organelles
E. eurystomus
FLUTAX
immunofluorescence
γ-tubulin
Opis:
This study aimed to investigate the assembly characteristics of ciliature and cortical microtubules and the localization of tubulins in different depths and regions of the cortex. The hypotrichous ciliates have closely arranged cilia and a highly complex microtubular system. Direct fluorescence and immunofluorescence labeling were used to observe ciliary organelles and cortical microtubular cytoskeleton in Euplotes eurystomus. An immunofluorescence analysis demonstrated that α-tubulin localized to the ventral and dorsal ciliary organelles and their associated microtubules, while γ-tubulin localized to the basal bodies of ciliary organelles, macronuclear membrane, and excretory pore of a contractile vacuole in the interphase. A direct fluorescence analysis showed that the ciliature and cortical microtubules in the deep cortex were more clearly marked by fluorescent taxoid (FLUTAX). Interestingly, α- and γ-tubulins also colocalized to the ringlike ciliary base–associated microtubules of dorsal kineties. The short microtubular bundles between the bases of transverse cirri could be marked by FLUTAX and γ-tubulin rather than α-tubulin, suggesting that tubulins in cortical microtubules in E. eurystomus varied, and the differentiation of cortical microtubules in the hypotrichous ciliate tended to be versatile. Also, during morphogenesis, γ-tubulin also localized to the base of ciliary primordium, where new basal bodies were formed, suggesting that the endocellular position of γ-tubulin in ciliates was related to basal bodies and regulated by the cell cycle. This study might help understand the assembly characteristics and tubulin composition of microtubules in different depths and regions of the cortex in hypotrichous ciliate E. eurystomus.
Źródło:
Acta Protozoologica; 2017, 56, 3; 149-160
0065-1583
1689-0027
Pojawia się w:
Acta Protozoologica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Permeability of N, P, K-fertilizer nutrient and water vapor through PLA, PLA/PS, and PLA/HA membranes
Autorzy:
Deng, Xiaonan
Ye, Sihong
Liu, Kun
Li, Changfeng
Liu, Fangzhi
Yan, Xiaoming
Powiązania:
https://bibliotekanauki.pl/articles/777994.pdf
Data publikacji:
2020
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
Permeability
polymer-coated fertilizer
mathematical model
poly lactic acid
membrane
Opis:
To collect permeability data and establish its database of fertilizer nutrients and water vapor through different polymer membranes for the development of polymer-coated fertilizer, the permeabilities of N-, P-, and K-nutrient from saturated aqueous of urea, NaH2PO4 and KCl solution and the permeability of water vapor through the membranes of poly lactic acid (PLA), its blends with polystyrene (PS), and its composites with humic acid (HA) particles were determined experimentally at the temperatures of 288, 298, and 308 K, respectively. The effects of the addition of PS and HA particles, temperature, and coating thickness on the permeability of fertilizer nutrient and water vapor were investigated. It was found that the addition of PS and HA increased the permeability for both the fertilizer nutrients and water vapor. The increase in temperature raised the permeability of N-, P-, and K-nutrient while decrease the permeability of water vapor in the range studied.
Źródło:
Polish Journal of Chemical Technology; 2020, 22, 4; 61-68
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The influence of thermophysical properties of frozen soil on the temperature of the cast-in-place concrete pile in a negative temperature environment
Autorzy:
Liu, Ziying
Yu, Tianlai
Yan, Ning
Gu, Lipeng
Powiązania:
https://bibliotekanauki.pl/articles/27312226.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
thermal properties
frozen soils
cast-in-place
concrete pile
negative temperature environment
ice
permafrost
heat conductivity coefficient
Opis:
Thermophysical properties of frozen soil have a great influence on the quality of cast-in-place concrete piles. In this paper, the embedded concrete temperature monitoring system is used to test the variation law of the concrete temperature during the construction of the bored pile. Thermophysical properties of permafrost around piles are tested. Based on the theory of three-phase unsteady heat conduction of soil, the influence of specific heat capacity, thermal conductivity, thermal diffusivity, and latent heat of phase transformation on the temperature change of a concrete pile is systematically studied. The thermal parameter is obtained which exerts the most significant influence on the temperature field. According to the influence degree of frozen soil on pile temperature, the order from high to low is thermal conductivity, thermal diffusivity, latent heat of phase change, and specific heat capacity. The changes in pile wall temperature caused by the change of these properties range between 2.60–10.97◦C, 1.49– 9.39◦C, 2.16–2.36◦C, and 0.24–3.45◦C, respectively. The change percentages of parameters vary between 35.77–47.12%, 12.22–40.20%, 12.46–32.25%, and 3.83–20.31%, respectively. Therefore, when designing and constructing concrete foundation piles, the influence of the thermal conductivity of frozen soil on concrete pile temperature should be considered first. The differences between the simulated and measured temperature along the concrete pile in the frozen soil varying with the respective thermal properties are: –2.99– 7.98◦C, –1.89–4.99◦C, –1.20–1.99◦C, and –1.76–1.27◦C. Polyurethane foam and other materials with small thermal conductivity can be added around the pile to achieve pile insulation.
Źródło:
Archives of Thermodynamics; 2023, 44, 2; 21--48
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research on capacity of mixed vessels traffic flow based on vessel-following theory
Autorzy:
Zhao, C.
Yan, H.
Zhou, G.
Liu, T.
Powiązania:
https://bibliotekanauki.pl/articles/2211979.pdf
Data publikacji:
2022
Wydawca:
Uniwersytet Morski w Gdyni. Wydział Nawigacyjny
Tematy:
vessel traffic flow
vessel-following theory
vessel traffic
vessel-following sequence
traffic characteristics
follow theoretical analysis diagram
maritime traffic engineering
traffic flow theory
Opis:
In order to study the characteristics of mixed vessel traffic flow, based on classical head distance model and probability analysis, by studying the combination time head way of different vessel-following sequences, the capacity model of mixed vessels traffic flow was established. Through analyzing two representative types of vessels, research results indicate that the capacity of mixed traffic increase with the traffic flow speed in a certain speed range, but the increasing trend slow down. The closer length and inertial stopping distance of different kind vessels are, the more capacity of mixed traffic increases. And the influence of reaction time on the capacity is related to proportion of different kind vessels.
Źródło:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2022, 16, 3; 535--539
2083-6473
2083-6481
Pojawia się w:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Copper Powder Morphology on the Microstructure and Properties of Copper Matrix Bulk Composites Reinforced with Ni-doped Graphene
Autorzy:
Liu, Jituo
Wang, Xianhui
Liu, Jia
Li, Hangyu
Liang, Yan
Ren, Jingyi
Powiązania:
https://bibliotekanauki.pl/articles/2048818.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Ni-doped graphene
copper base composite
copper powder morphology
mechanical properties
Opis:
To clarify the effect of copper powder morphology on the microstructure and properties of copper matrix bulk composites reinforced with Ni-doped graphene, spherical and dendritic copper powders were selected to fabricate the Ni-doped graphene reinforced copper matrix bulk composites. The Ni-doped graphene were synthesized by hydrothermal reduction method, followed by mixing with copper powders, and then consolidated by spark plasma sintering. It is found that the Ni-doped graphene are well bonded with the dendritic copper powder, whereas Ni-doped graphene are relatively independent on the spherical copper powder. The copper base bulk composite prepared by the dendritic copper powder has better properties than that prepared by spherical copper powder. At 0.5wt.% Ni-doped graphene, the dendritic copper base bulk composite has a good combination of hardness, electrical conductivity and yield strength, which are 81.62 HV, 87.93% IACS and 164 MPa, respectively.
Źródło:
Archives of Metallurgy and Materials; 2022, 67, 1; 341-348
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Image compression and encryption algorithm with wavelet-transform-based 2D compressive sensing
Autorzy:
Fan, Jing-Hui
Liu, Xian-Bao
Chen, Yan-Bin
Powiązania:
https://bibliotekanauki.pl/articles/175122.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
wavelet transform
compressive sensing
chaos scrambling
image encryption
image compression
Opis:
By combining a wavelet transform with chaos scrambling, an image compression and encryption algorithm based on 2D compressive sensing is designed. The wavelet transform is employed to obtain the sparse representation of a plaintext image. The sparse image is measured in two orthogonal directions by compressive sensing. Then, the result of 2D compressive sensing is confused by the Arnold transform and the random pixel scrambling. The combination of four-dimensional chaos and logistic map is exploited to generate the first row of the key-controlled circulant matrix. The proposed algorithm not only carries out image compression and encryption simultaneously, but also reduces the consumption of the key by controlling the generation of measurement matrix. Experimental results reveal that the proposed image compression and encryption algorithm is resistant to noise attacks with good compression performance and high key sensitivity.
Źródło:
Optica Applicata; 2019, 49, 3; 461-472
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of Metal Oxides on the Thermal Decomposition Kinetics and Mechanisms of HAN/PVA Based Propellants
Autorzy:
Hu, Song-qi
Liu, Xue-li
Liu, Lin-Lin
Kang, Bo
Zhang, Yan
Powiązania:
https://bibliotekanauki.pl/articles/27787991.pdf
Data publikacji:
2021
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
HAN/PVA-based propellant
metal oxides
catalytic behaviour
kinetic parameters
Opis:
The thermal decomposition processes of HAN/PVA-based propellants have been investigated using a simultaneous thermogravimetric analysis (TGA) – differential scanning calorimetry (DSC), coupled with Fourier-Transform Infrared Spectroscopy (FTIR) and Mass Spectrometry (MS) system. The activation energy (Ea), pre-exponential factor A and reaction mechanism function f(α) of the decomposition processes have been determined by non-isothermal and Malek methods. The results showed that the decomposition process of an HAN/PVA sample occurs mainly in the temperature range 202.2~220.1 °C, with a mass loss, heat release and Ea of about 84.8%, 1474.18 and 88.76 kJ·mol–1, respectively. Of the seven metal oxides studied as catalysts, Al2O3, V2O5 and Fe2O3 have significant catalytic effects on an HAN/PVA-based propellant, in lowering the decomposition temperature, with Ea changing from 88.8 to 83.7, 85.6 and 113.6 kJ·mol–1, respectively. The f(α) of both HAN/PVA and HAN/PVA/Al2O3 samples can be expressed as f(α) = (1 – α)2, whereas f(α) = α or f(α) = α/2 fit well for the HAN/PVA/V2O5 and HAN/PVA/Fe2O3 samples.
Źródło:
Central European Journal of Energetic Materials; 2021, 18, 3; 322-338
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
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