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    Wyświetlanie 1-15 z 15
    Tytuł:
    Acoustic Matching Characteristics of Annular Piezoelectric Ultrasonic Sensor
    Autorzy:
    Li, Haoran
    Hu, Yan
    Li, Laibo
    Xu, Dongyu
    Powiązania:
    https://bibliotekanauki.pl/articles/2141675.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    piezoelectric ceramics
    ultrasonic sensors
    acoustic matching characteristics
    Opis:
    Using intelligent materials and sensors to monitor the safety of concrete structures is a hot topic in the field of civil engineering. In order to realize the omni-directional monitoring of concrete structural damage, the authors of this paper designed and fabricated an embedded annular piezoelectric ultrasonic sensor using the annular piezoelectric lead zirconate titanate (PZT) ceramic as a sensing element and epoxy resin as the matching and the backing layers. The influence of different matching and backing layers thickness on the acoustic characteristic parameters of the sensor were studied. The results show that the resonant frequency corresponding to the axial mode of annular piezoelectric ceramics moves toward the high frequency direction with the decrease of the height of piezoelectric ceramics, and the radial vibration mode increases as well as the impedance peak. With the thickness of the backing layer increases from 1 mm to 2 mm, the radial resolution of the annular piezoelectric ultrasonic sensor is enhanced, the pulse width is reduced by 39% comparing with the sensors which backing layer is 1 mm, and the head wave amplitude and −3 dB bandwidth are increased by 61% and 66%, respectively. When the matching layer thickness is 3 mm, the sensor has the highest amplitude response of 269 mV and higher sensitivity.
    Źródło:
    Archives of Acoustics; 2022, 47, 2; 275-284
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Equivalent Model of the DC Resistance of Nonwoven-Based Embroidery Conductive Lines with Embroidery Parameters
    Równoważny model rezystancji prądu stałego dla włóknin z liniami przewodzącymi uwzględniający parametry procesu haftowania
    Autorzy:
    Zhang, Yaya
    Hu, Jiyong
    Yan, Xiong
    Powiązania:
    https://bibliotekanauki.pl/articles/232238.pdf
    Data publikacji:
    2020
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Biopolimerów i Włókien Chemicznych
    Tematy:
    textiles
    conductive line
    embroidery parameter
    direct current resistance
    tekstylia
    linia przewodząca
    parametr haftu
    rezystancja prądu stałego
    Opis:
    Although embroidering technology is generally used to manufacture electronic components, previous works only give the fitting relationship between embroidery parameters and their direct current (DC) resistance. However, to manufacture embroidered electronic components in scale, the relationship between their DC resistance and embroidery parameters must be known in the computer aided embroidery system. This study investigated the effect of embroidery parameters, including stitch spacing, stitch length and embroidery tension, on the DC resistance of embroidery conductive lines using a peripheral needle, and established their equivalent resistance model in terms of the properties of conductive yarns and embroidery parameters. To verify the model, conductive lines with different embroidery parameters were embroidered on polyester nonwoven, and their DC resistance were tested and fitted. The results show that DC resistance can be effectively controlled by adjusting embroidery parameters. The model proposed is verified and can be used to predict the DC resistance of conductive lines with predesigned parameters.
    Technologia haftowania jest szeroko stosowana do produkcji elementów elektronicznych, jednakże dotychczas opublikowane prace opisywały jedynie związek pomiędzy parametrami haftu a ich rezystancją prądu stałego (DC). Jednak, aby wyprodukować haftowane elementy elektroniczne musi być znany związek między ich rezystancją prądu stałego a parametrami haftu. W pracy przedstawiono wyniki badań wpływu parametrów haftu, w tym odstępu ściegu, długości ściegu i napięcia haftu, na rezystancję linii przewodzących. Ustalono równoważny model rezystancji z uwzględnieniem właściwości przędz przewodzących i parametrów procesu haftowania. Aby zweryfikować model na włókninie poliestrowej wyhaftowano linie przewodzące stosując różne parametry haftu, a następnie zbadano ich rezystancję na prąd stały. Wyniki pokazały, że rezystancję prądu stałego można skutecznie kontrolować poprzez dostosowanie parametrów haftu. Zaproponowany model został zweryfikowany i może być wykorzystany do przewidywania rezystancji prądu stałego linii przewodzących o wstępnie zaprojektowanych parametrach.
    Źródło:
    Fibres & Textiles in Eastern Europe; 2020, 2 (140); 35-42
    1230-3666
    2300-7354
    Pojawia się w:
    Fibres & Textiles in Eastern Europe
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A convolutional neural network-based method of inverter fault diagnosis in a ship’s DC electrical system
    Autorzy:
    Yan, Guohua
    Hu, Yihuai
    Shi, Qingguo
    Powiązania:
    https://bibliotekanauki.pl/articles/32898224.pdf
    Data publikacji:
    2022
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    multi-energy hybrid ships
    inverters
    fault diagnosis
    CNN
    Opis:
    Multi-energy hybrid ships are compatible with multiple forms of new energy, and have become one of the most important directions for future developments in this field. A propulsion inverter is an important component of a hybrid DC electrical system, and its reliability has great significance in terms of safe navigation of the ship. A fault diagnosis method based on one-dimensional convolutional neural network (CNN) is proposed that considers the mutual influence between an inverter fault and a limited ship power grid. A tiled voltage reduction method is used for one-to-one correspondence between the inverter output voltage and switching combinations, followed by a combination of a global average pooling layer and a fully connected layer to reduce the model overfitting problem. Finally, fault diagnosis is verified by a Softmax layer with good anti-interference performance and accuracy.
    Źródło:
    Polish Maritime Research; 2022, 4; 105-114
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A novel fault diagnosis method for marine blower with vibration signals
    Autorzy:
    Yan, Guohua
    Hu, Yihuai
    Jiang, Jiawei
    Powiązania:
    https://bibliotekanauki.pl/articles/32899234.pdf
    Data publikacji:
    2022
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    fault diagnosis
    marine blower
    EEMD
    correlation coefficient
    AR spectrum
    BPNN
    Opis:
    The vibration signals on marine blowers are non-linear and non-stationary. In addition, the equipment in marine engine room is numerous and affects each other, which makes it difficult to extract fault features of vibration signals in the time domain. This paper proposes a fault diagnosis method based on the combination of Ensemble Empirical Mode Decomposition (EEMD), an Autoregressive model (AR model) and the correlation coefficient method. Firstly, a series of Intrinsic Mode Function (IMF) components were obtained after the vibration signal was decomposed by EEMD. Secondly, effective IMF components were selected by the correlation coefficient method. AR models were established and the power spectrum was analysed. It was verified that blower failure can be accurately diagnosed. In addition, an intelligent diagnosis method was proposed based on the combination of EEMD energy and a Back Propagation Neural Network (BPNN), with a correlation coefficient method to get effective IMF components, and the energy components were calculated, normalised as a feature vector. Finally, the feature vector was sent to the BPNN for training and state recognition. The results indicated that the EEMD-BPNN intelligent fault diagnosis method is suitable for higly accurate fault diagnosis of marine blowers.
    Źródło:
    Polish Maritime Research; 2022, 2; 77-86
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Fault diagnosis of me marine diesel engine fuel injector with novel IRCMDE method
    Autorzy:
    Shi, Qingguo
    Hu, Yihuai
    Yan, Guohua
    Powiązania:
    https://bibliotekanauki.pl/articles/34608122.pdf
    Data publikacji:
    2023
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    marine diesel engine
    fuel injector
    improved refined composite multi-scale dispersion entropy
    fault diagnosis
    Opis:
    As an important component of the fuel injection system, the fuel injector is crucial for ensuring the power, economy, and emissions for a whole ME (machine electronically-controlled) marine diesel engine. However, injectors are most prone to failures such as reduced pressure at the opening valve, clogged spray holes and worn needle valves, because of the harsh working conditions. The failure characteristics are non-stationary and non-linear. Therefore, to efficiently extract fault features, an improved refined composite multi-scale dispersion entropy (IRCMDE) is proposed, which uses the energy distribution of sampling points as weights for coarse-grained calculation, then fast correlation-based filter (FCBF) and support vector machine (SVM) are used for feature selection and fault classification, respectively. The experimental results from a MAN B&W 6S35ME-B9 marine diesel engine show that the proposed algorithm can achieve 92.12% fault accuracy for injector faults, which is higher than multiscale dispersion entropy (MDE), refined composite multiscale dispersion entropy (RCMDE) and multiscale permutation entropy (MPE). Moreover, the experiment has also proved that, due to the double-walled structure of the high-pressure fuel pipe, the fuel injection pressure signal is more accurate than the vibration signal in reflecting the injector operating conditions.
    Źródło:
    Polish Maritime Research; 2023, 3; 96-110
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Hierarchical multiscale fluctuation dispersion entropy for fuel injection system fault diagnosis
    Autorzy:
    Shi, Qingguo
    Hu, Yihuai
    Yan, Guohua
    Powiązania:
    https://bibliotekanauki.pl/articles/32915909.pdf
    Data publikacji:
    2023
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    hierarchical multiscale fluctuation dispersion entropy
    fuel injection system
    support matrix machine
    fault diagnosis
    Opis:
    Marine electronically controlled (ME) two-stroke diesel engines occupy the highest market share in newly-built ships and its fuel injection system is quite different and important. Fault diagnosis in the fuel injection system is crucial to ensure the power, economy and emission of ME diesel engines, so we introduce hierarchical multiscale fluctuation dispersion entropy (HMFDE) and a support matrix machine (SMM) to realise it. We also discuss the influence of parameter changes on the entropy calculation’s accuracy and efficiency. The system simulation model is established and verified by Amesim software, and then HMFDE is used to extract a matrix from the features of a high pressure signal in a common rail pipe, under four working conditions. Compared with vectorised HMFDE, the accuracy of fault diagnosis using SMM is nearly 3% higher than that using a support vector machine (SVM). Experiments also show that the proposed method is more accurate and stable when compared with hierarchical multiscale dispersion entropy (HMDE), hierarchical dispersion entropy (HDE), multiscale fluctuation dispersion entropy (MFDE), multiscale dispersion entropy (MDE) and multiscale sample entropy (MSE). Therefore, the proposed method is more suitable for the modelling data. This research provides a new direction for matrix learning applications in fault diagnosis in marine two-stroke diesel engines.
    Źródło:
    Polish Maritime Research; 2023, 1; 98-111
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Fault diagnosis of bearings based on SSWT, bayes optimisation and CNN
    Autorzy:
    Yan, Guohua
    Hu, Yihuai
    Shi, Qingguo
    Powiązania:
    https://bibliotekanauki.pl/articles/34610052.pdf
    Data publikacji:
    2023
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    fault diagnosis
    bearing
    PMSM
    bayesian optimisation
    CNN
    Opis:
    Bearings are important components of rotating machinery and transmission systems, and are often damaged by wear, overload and shocks. Due to the low resolution of traditional time-frequency analysis for the diagnosis of bearing faults, a synchrosqueezed wavelet transform (SSWT) is proposed to improve the resolution. An improved convolutional neural network fault diagnosis model is proposed in this paper, and a Bayesian optimisation method is applied to automatically adjust the structure and hyperparameters of the model to improve the accuracy of bearing fault diagnosis. Experimental results from the accelerated life testing of bearings show that the proposed method is able to accurately identify various types of bearing fault and the different status of these faults under complex running conditions, while achieving very good generalisation ability.
    Źródło:
    Polish Maritime Research; 2023, 3; 132-141
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Design and mechanical analysis of a composite T-type connection structure for marine structures
    Autorzy:
    Li, Xiaowen
    Zhu, Zhaoyi
    Li, Yan
    Hu, Zhe
    Powiązania:
    https://bibliotekanauki.pl/articles/260625.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    T-type connection structure
    composite structure design
    test
    mechanical analysis
    marine structure
    Opis:
    A new T-type connection structure consisting of composite sandwich plates, reinforced cores and adhesive was proposed for the construction of lightweight ships to resolve connection problems between bulkheads and decks of composite lightweight ship superstructures. Based on the design principles and mechanical properties of composite structures, the mechanical behaviour of the structure under a dangerous loading condition was investigated. In addition, the ultimate bearing capacities and damage modes were examined, the results of which demonstrated that the strength of the structure is weak, and that the adhesive and reinforced core between the face plate and the web plate is the primary weakness of the structure. A numerical simulation method was verified using the results of the mechanical tests, and five characteristic paths at the connection area were established. The stresses and displacements along the five paths were calculated using the numerical method. Then, variations in the geometric parameter and the strength and weight of the connection were summarised. The optimal angle of the adhesive bonding area is approximately 60°, which supports the optimal design and practical application of the lightweight ship adhesive-bonded connection structure.
    Źródło:
    Polish Maritime Research; 2020, 2; 145-157
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Simultaneous removal of phenol and Cu(II) from wastewater by tallow dihydroxyethyl betaine modified bentonite
    Autorzy:
    Hu, Xiangyang
    Wang, Bao
    Yan, Gengsheng
    Ge, Bizhou
    Powiązania:
    https://bibliotekanauki.pl/articles/2203123.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    simultaneous adsorption
    tallow dihydroxyethyl betaine
    bentonite
    Cu(II)
    phenol
    Opis:
    An organobentonite modified with an amphoteric surfactant, tallow dihydroxyethyl betaine (TDHEB), was used as an adsorbent to simultaneously remove Cu(II) and phenol from wastewater. The characteristic of the organobentonite (named TDHEB-bentonite) was analyzed by X-ray diffraction, Fourier-transform infrared spectra and nitrogen adsorption-desorption isotherm. Batch tests were conducted to evaluate the adsorption capacities of TDHEB-bentonite for the two contaminants. Experiment results demonstrated that the adsorption of both contaminants is highly pH-dependent under acidic conditions. TDHEB-bentonite had about 2.0 and 5.0 times higher adsorption capacity toward Cu(II) and phenol, respectively, relative to the corresponding raw Na-bentonite. Adsorption isotherm data showed that the adsorption processes of both contaminants were well described by Freundlich model. Kinetic experiment demonstrated that both contaminants adsorption processes correlated well with pseudo-second-order model. Cu(II) had a negative impact on phenol adsorption, but not vice versa. Cu(II) was removed mainly through chelating with the organic groups (-CH2CH2OH and -COO-) of TDHEB. Otherwise, partition into the organic phase derived from the adsorbed surfactant was the primarily mechanism for phenol removal. Overall, TDHEB-bentonite was a promising adsorbent for removing Cu(II) and phenol simultaneously from wastewater.
    Źródło:
    Archives of Environmental Protection; 2022, 48, 3; 37--47
    2083-4772
    2083-4810
    Pojawia się w:
    Archives of Environmental Protection
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Deep learning-based fault diagnosis for marine centrifugal fan
    Autorzy:
    Li, Congyue
    Hu, Yihuai
    Jiang, Jiawei
    Yan, Guohua
    Powiązania:
    https://bibliotekanauki.pl/articles/32917700.pdf
    Data publikacji:
    2023
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    CEEMDAN
    fault diagnosis
    lightweight neural network
    marine centrifugal fan
    Opis:
    Marine centrifugal fans usually work in harsh environments. Their vibration signals are non-linear. The traditional fault diagnosis methods of fans require much calculation and have low operating efficiency. Only shallow fault features can be extracted. As a result, the diagnosis accuracy is not high. It is difficult to realize the end-to-end fault diagnosis. Combining the Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (CEEMDAN) and lightweight neural network, a fault classification method is proposed. First, the CEEMDAN can decompose the vibration signal into several intrinsic modal functions (IMF). Then, the original signals can be transformed into 2-D images through pseudocolour coding of the IMFs. Finally, they are fed into the lightweight neural network for fault diagnosis. By embedding a convolutional block attention module (CBAM), the ability of the network to extract critical feature information is improved. The results show that the proposed method can adaptively extract the fault characteristics of a marine centrifugal fan. While the model is lightweight, the overall diagnostic accuracy can reach 99.3%. As exploratory basic research, this method can provide a reference for intelligent fault diagnosis systems on ships.
    Źródło:
    Polish Maritime Research; 2023, 1; 112-120
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Association of SRAP markers with juvenile wood basic density and growth traits in Cunninghamia lanceolata (Lamb.) Hook
    Autorzy:
    Hu, Dehuo
    Su, Yan
    Wu, Shujuan
    Wu, Jiezhen
    Wang, Runhui
    Yan, Shu
    Wei, Ruping
    Zheng, Huiquan
    Powiązania:
    https://bibliotekanauki.pl/articles/956957.pdf
    Data publikacji:
    2018
    Wydawca:
    Polska Akademia Nauk. Instytut Dendrologii PAN
    Tematy:
    chinese fir
    srap
    diversity
    wood basic density
    association analysis
    Opis:
    Application of sequence-related amplified polymorphism (SRAP) markers to unravel variations and relationships with biological and morphological traits has been reported in a variety of plant species, and their potential for breeding has also been highlighted. (1) Assess the diversity level of a Cunninghamia lanceolata (Chinese fir) genetic panel based on phenotypic traits and SRAP markers, (2) identify SRAP loci linked to juvenile wood basic density (JWBD) and growth traits, and (3) address the overlap of the trait-associated SRAP markers during the juvenile and mature stages of this species. A total of 227 Chinese fir genotypes were subjected to phenotype, SRAP genotyping, and marker-trait association analyses. A total of 564 unambiguous SRAP bands and 558 polymorphic loci were identified from the genotypes. The overall percentage of polymorphic bands, polymorphism information content, Nei’s gene diversity, and Shannon’s Information Index were 98.9%, 0.2576, 0.3196 and 0.4838, respectively. An analysis of molecular variance further demonstrated that the genotypes varied significantly at SRAP polymorphisms (p < 0.01). A wide genetic distance span from 0.0531 to 0.9097 was also observed; most (94.9%) fell within the range of 0.3000–0.6999. An association analysis based on general linear model (GLM) and mixed linear model (MLM) unraveled 21, 26, 25, and 19 marker-trait associations for JWBD, height (H), diameter at breast height (DBH, 1.3 m) and stem volume (V), respectively. These marker-trait associations corresponded to 64 different SRAP markers; 46 of these were linked to only one trait, while the other 18 markers appeared to be associated with more than one trait but limited to growth traits. Overall, the SRAP markers represented R2 (percentage of the phenotypic variation explained by marker) values of 1.7–9.2% for the GLM and 1.7–5.6% for the MLM. Strikingly, the significant trait-associated marker list seemed to be rather different from that of the previous study performed on mature traits (WBD, H, DBH and V), except for overlap of two markers. This study demonstrated an association of SRAP markers with JWBD and growth traits in Chinese fir. The results further our understanding of the genetic basis of the Chinese fir WBD and growth traits at the juvenile stage.
    Źródło:
    Dendrobiology; 2018, 79; 111-118
    1641-1307
    Pojawia się w:
    Dendrobiology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Global transcriptome analysis reveals genes associated with seedling advance growth traits in a selfed family of Chinese fir (Cunninghamia lanceolata)
    Autorzy:
    Deng, H.
    Hu, D.
    Wei, R.
    Yan, S.
    Wang, R.
    Zheng, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/2130183.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Instytut Dendrologii PAN
    Tematy:
    Chinese fir
    selfing
    RNA-Seq
    growth trait
    hub gene
    Opis:
    Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) is a major timber conifer species in southern China. In this study, we aimed to capture the rarely advanced phenomenon for selfing in this species and illustrated the underlying molecular mechanism, especially the hub gene-regulated networks and pathways, by global transcriptome analysis assays (RNA-Seq). Self-pollination trials revealed a wide variation of selfing effects among parents. Parent cx569 produced a selfed family with the best growth performance at the seedling stage. The growth-based extremely advanced (AD) (n=3) and depressed (DE) variants (n=3; different types) were then subjected to comparative RNA-Seq. The transcriptome data revealed more than 5000 differentially expressed genes (DEGs) for each comparison group (AD versus DE). Weighted gene co-expression network analysis (WGCNA) further identified more than 80 important DEGs that were significantly associated with growth traits in each comparison group. A subsequent enrichment analysis showed that the identified DEGs belonged to six main types, including xylem metabolism-related, sugar and energy metabolism-related, plant hormone signal transduction-related, stress response-related, cytochrome-related, and transcription factor genes. Ten hub genes represented by the ERF071, MYB-relate 305, WRKY6, WRKY31, PER3, LAC4, CESA8, CESA9, GID1, and PR1 genes were co-identified between AD and DE variants. These genes exhibited rather different expression patterns between AD and DE variants, especially of the transcription factor ERF071 gene that presented a low transcript level in the AD seedlings with only 4.45% activity compared to DE's. While, the plant hormone signal transduction GID1 gene was significantly upregulated in AD by about 20-fold when compared to DE's, and fold change of the lignin biosynthesis-related PER3, CESA9 and LAC4 gene expression parallel reached to 10–15 times in an upregulation pattern in AD seedlings. The set of hub gene-linked interaction networks and pathways revealed in this study may be responsible for the rarely advanced phenomenon for selfing at the seedling stage in Chinese fir.
    Źródło:
    Dendrobiology; 2022, 87; 27-46
    1641-1307
    Pojawia się w:
    Dendrobiology
    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
    Tytuł:
    First-Principles Calculations for Structural, Elastic, Electronic and Thermodynamic Properties of $HfZn_{2}$ under Pressure
    Autorzy:
    Li, Guo-Jun
    Shi, Lan-Ting
    Hu, Cui-E
    Cheng, Yan
    Ji, Guang-Fu
    Powiązania:
    https://bibliotekanauki.pl/articles/1398192.pdf
    Data publikacji:
    2018-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    C15 Laves-phase
    elastic properties
    electronic structure
    vibrational properties
    quasi-harmonic approximation
    Opis:
    By using density functional theory within the Perdew-Burke-Ernzerhof generalized gradient approximation implemented in the VASP code, we study the structural, elastic, electronic, and thermodynamic properties of C15 Laves-phase compound $HfZn_{2}$. Comparing the lattice constants calculated from the Perdew-Burke-Ernzerhof generalized gradient approximation and local density approximation, we find that the former is in better agreement with the experimental data. The elastic constants of $HfZn_{2}$ calculated by strain-stress method indicate that they keep stable up to 100 GPa. The bonding characteristics are discussed by analyzing the energy band structure, charge density distribution and charge density difference. Phonon dispersion curves and phonon density of states of HfZn_{2} at the different pressure are predicted for the first time. In addition, there is no imaginary frequency in the phonon band at different pressure, which also shows that $HfZn_{2}$ is stable up to 100 GPa. Vibrational models are also illustrated based on phonon and group theory. The thermodynamic properties under high temperature and high pressure are calculated by different thermodynamic models. The heat capacity at constant pressure and low temperature calculated by quasi-harmonic approximation is more close to the measurement than that calculated by quasi-harmonic Debye models.
    Źródło:
    Acta Physica Polonica A; 2018, 133, 5; 1299-1306
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effectiveness of fly ash on the stabilization/solidification of Zn-contaminated soil
    Autorzy:
    Chen, Yan
    Zhu, Shengyuan
    Fang, Wei
    Huang, He
    Qin, Hao
    Hu, Shengtao
    Wu, Yuzhao
    Powiązania:
    https://bibliotekanauki.pl/articles/27323977.pdf
    Data publikacji:
    2023
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    fly ash
    soil
    heavy metals
    X-ray diffraction
    Zn2+
    popiół lotny
    gleba
    metale ciężkie
    dyfrakcja rentgenowska
    Opis:
    As a solid waste, the associated disposal cost of fly ash is really high. Previous studies suggested that the utilization of fly ash to treat heavy metal-contaminated soils was a new cost-effective method of disposal of it. Therefore, the effectiveness of fly ash stabilized/solidified Zn-contaminated soils has been investigated by unconfined compressive strength (UCS) and toxicity characteristics leaching procedure (TCLP) tests. Quantitative analysis of the soil microstructure was conducted by processing the X-ray diffraction (XRD) and scanning electron microscope (SEM) images. Mercury intrusion porosimetry (MIP) was carried out to illustrate the size and proportion of pore size for specimens under different ratios. The results of the tests showed an improvement in the UCS, which further increased as the content of binders was raised. Binder content would have little influence on the development of strength if the binder content exceeds a threshold value. The leached Zn2+ concentration of stabilized specimens was significantly decreased compared to that of untreated. Quantitative analysis confirmed that the addition of the binders resulted in the amount of hydration product, reduction of porosity, and a really random pores orientation, which was responsible for the improvement of the strength and leaching properties of the Zn2+ contaminated soils.
    Źródło:
    Environment Protection Engineering; 2023, 49, 3; 15--29
    0324-8828
    Pojawia się w:
    Environment Protection Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
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