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Wyświetlanie 1-10 z 10
Tytuł:
A machine learning-based mobile robot visual homing approach
Autorzy:
Zhu, Q.
Ji, X.
Wang, J.
Cai, C.
Powiązania:
https://bibliotekanauki.pl/articles/201706.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
robot navigation
visual homing
panoramic vision sensors
machine learning
homing performance
nawigacja robotów
panoramiczny czujnik wizyjny
uczenie maszynowe
Opis:
Visual homing enables mobile robots to move towards a previously visited location solely based on panoramic vision sensors. In this paper, a SIFT-based visual homing approach incorporating machine learning is presented. The proposed approach can reduce the impact of inaccurate landmarks on the performance, and generate more precise home direction with simple model. The effectiveness of the proposed approach is verified on both panoramic image databases and actual mobile robot, experimental results reveal that compared to some traditional visual homing methods, the proposed approach exhibits better homing performance and adaptability in both static and dynamic environments.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2018, 66, 5; 621-634
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Unravelling the Effect of Anthraquinone Metal Salts as Wide-range Plateau Catalysts to Enhance the Combustion Properties of Solid Propellants
Autorzy:
Wang, Y.
Yan, Q.-L.
An, T.
Chen, B.
Ji, Y.-P.
Wang, W.
Zhao, F.
Powiązania:
https://bibliotekanauki.pl/articles/358042.pdf
Data publikacji:
2018
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
solid propellants
burning rate catalysts
anthraquinone metal salts
wide-range plateau combustion
Opis:
Novel lead and copper salts based on anthraquinone, including 1,8-dihydroxyanthraquinone,1,4,5,8-tetrahydroxyanthraquinone and 1,8-dihydroxy-4,5-dinitroanthraquinone, were prepared and characterized by Fourier transform infrared spectroscopy (FTIR), elemental analysis (EA), and X-ray fluorescence (XRF). The catalytic effects of these compounds on the decomposition of nitrocellulose (NC) and on the combustion properties of double-base (DB) and composite modified double-base (CMDB) propellants were comprehensively investigated. The results demonstrated that the burning rate is significantly increased (by 200%) in the lower pressure range (2-6 MPa) as compared to the control systems without added anthraquinone-based salts. Concurrently, the pressure exponents (n) were obviously lower, exhibiting a “wide-range plateau” combustion phenomenon in the middle-pressure region. Specifically, for the DB propellants such a plateau region extended from 10 MPa to 16 MPa for n equal to 0.10, from 10 MPa to 18 MPa for n equal to 0.11 and from 8 MPa to 18 MPa when n is 0.05. In the case of RDX-CMDB propellants, the plateau was found to be in the range 6-18 MPa, with n in the range 0.16-0.27, depending on the type of catalyst, in contrast to the reference CMDB sample, which was characterized by n equal to 0.7 for the same pressure range.
Źródło:
Central European Journal of Energetic Materials; 2018, 15, 2; 376-390
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ethnobotany of Acorus in China
Autorzy:
Shu, H.
Zhang, S.
Lei, Q.
Zhou, J.
Ji, Y.
Luo, B.
Hong, L.
Li, F.
Liu, B.
Long, C.
Powiązania:
https://bibliotekanauki.pl/articles/59160.pdf
Data publikacji:
2018
Wydawca:
Polskie Towarzystwo Botaniczne
Opis:
In China, species in the genus Acorus are used for many different purposes, viz., in traditional medicine, for rituals, and as ornamental plants. Acorus calamus (sweet flag) has been a symbolic plant in Chinese culture for many centuries and is used as a ceremonial object in festivals throughout the country. For other Acorus species in China, ethnobotanical records are few. During field investigations from 2006 to 2017, we interviewed 573 individuals representing ethnic groups such as the Miao, Yao, Buyi, Shui, Tujia, Dong, She, Maonan, Zhuang, Yi, and Han people. Various ethnobotanical approaches were adopted in the field surveys, including key informant interviews, semistructured interviews, participatory observation, direct observation, etc. The results have revealed a rich treasure trove of traditional knowledge on Acorus in China. Two species (A. macrospadiceus and A. gramineus) were used by ethnic groups as spices to add flavor to meat. Through the study found that all the species of Acorus had medicinal value, especially A. tatarinowii, deafness, blindness, and digestive disorders were among the conditions commonly treated using these plants. Traditional knowledge of the cultural, ethnomedicinal, and food values of Acorus, based on our recent literature surveys and field investigations in China is presented here. A better understanding of Acorus is vital for conserving the plants and the traditional knowledge associated with them.
Źródło:
Acta Societatis Botanicorum Poloniae; 2018, 87, 2
0001-6977
2083-9480
Pojawia się w:
Acta Societatis Botanicorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Coated Ammonium Dinitramide on the Properties of Nitrate-ester Plasticized Polyether Solid Rocket Propellants
Autorzy:
Pang, W. Q.
Li, J. Q.
DeLuca, L. T.
Ke, W.
Fu, X. L.
Zhong, F. X.
Li, H.
Ji, Y. P.
Powiązania:
https://bibliotekanauki.pl/articles/358292.pdf
Data publikacji:
2018
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
energetic materials
NEPE composite solid propellants
ADN
hazardous properties
combustion characteristics
Opis:
Several industrial and research types of nitrate-ester plasticized polyether (NEPE) solid propellants were experimentally analyzed. In general, their compositions differed in the mass fraction of ammonium dinitramide (ADN), which was used as a promising highly energetic filler, as an alternative to ammonium perchlorate (AP). ADN exhibits high performance, low signature and non-polluting characteristics. The propellant composition without ADN, but with AP, was used as the reference. The microstructure and granularity distribution of the uncoated and coated ADN particles were experimentally analyzed. It was found that uncoated ADN particles exhibited irregular shape, while the ADN particles after coating are spherical. Because of their irregular shape, uncoated ADN particles caused inferior processability of the propellant slurry when added to the propellant formulation. Consequently, the NEPE propellants with coated ADN were studied in further detail. The rheological properties, energetic properties, mechanical sensitivities and combustion properties (burning rate and pressure exponent) of the NEPE propellants with coated ADN were studied and compared with the reference NEPE propellant. The addition of ADN particles to the propellant formulations increased the standard theoretical specific impulse and heat of explosion of the propellants, while decreasing the density. The propellants containing ADN particles were much more sensitive to impact and friction compared to the reference sample. Moreover, increasing the ADN mass fraction in the propellant formulation can significantly affect the combustion behaviour and increase the burning rate and pressure exponent compared to of the reference formulation. However it appears that ADN is a very promising candidate as a new energetic material in compositions of NEPE propellants, although several important questions concerning ADN’s suitability, especially in the context of its sensitivity to friction and impact, remain to be answered.
Źródło:
Central European Journal of Energetic Materials; 2018, 15, 4; 590-609
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A new troodontid theropod from the Late Cretaceous of central China, and the radiation of Asian troodontids
Autorzy:
Lu, J
Xu, L.
Liu, Y.
Zhang, X.
Jia, S.
Ji, Q.
Powiązania:
https://bibliotekanauki.pl/articles/20912.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
new theropod
Late Cretaceous
Central China
Asian troodontid
troodontid
Theropoda
Troodontidae
Xixiasaurus
Cretaceous
Henan province
China
paleontology
Opis:
A new troodontid dinosaur, Xixiasaurus henanensis gen. et sp. nov., from the Upper Cretaceous Majiacun Formation of the Xixia Basin, Henan Province, is erected, based on a partial skull. It is characterized by bearing 22 maxillary teeth, a distinct opening on the lateral surface of the base of nasal process of the premaxilla, the rostral end of the upper jaw forming a tapered U−shape, and the mandibular symphyseal region slightly inflected medially. Xixiasaurus is most closely related to the Mongolian Byronosaurus among troodontids. Byronosaurus, Urbacodon, and Xixiasaurus may form a new clade, suggesting an endemic radiation of troodontids across Asia, including multiple taxa without dental serrations. The discovery of Xixiasaurus in the Xixia Basin may imply that the Xixiasaurus−bearing Majiacun Formation is Campanian in age.
Źródło:
Acta Palaeontologica Polonica; 2010, 55, 3; 381-388
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A partial skeleton of an enantiornithine bird from the Early Cretaceous of Northwestern China
Autorzy:
Lamanna, M.C.
You, H.-L.
Harris, J.D.
Chiappe, L.M.
Ji, S.-A.
Lu, J.-C.
Ji, Q.
Powiązania:
https://bibliotekanauki.pl/articles/20670.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
China
Cretaceous
Early Cretaceous
paleontology
skeleton
partial skeleton
bird
Aves
enantiornithine bird
Enantiornithes
Xiagou Formation
remains
Opis:
Although recent discoveries from Lower Cretaceous sediments in northeastern China have greatly improved our understanding of the initial stages of avian diversification in eastern Asia, the early evolution of Aves elsewhere on the continent remains poorly understood. In 2004, a collaborative field effort directed by personnel from the Chinese Academy of Geological Sciences and Carnegie Museum of Natural History recovered multiple partial to nearly complete avian skeletons from outcrops of the Lower Cretaceous Xiagou Formation exposed in the Changma Basin of northwestern Gansu Province, China. Here we describe a thrush−sized partial skeleton comprised of a fragmentary pelvic girdle and largely complete hind limbs. A phylogenetic analysis of 20 avian ingroup taxa and 169 anatomical characters places the specimen in Enantiornithes, and within that clade, in Euenantiornithes. When coupled with additional recent discoveries from the Changma Basin, the new skeleton improves our understanding of early avian evolution and diversification in central Asia.
Źródło:
Acta Palaeontologica Polonica; 2006, 51, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mobile robot visual homing by vector pre-assigned mechanism
Autorzy:
Ji, X.
Zhu, Q.
Wang, J.
Cai, C.
Ma, J.
Powiązania:
https://bibliotekanauki.pl/articles/201155.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
robot navigation
visual homing
panoramic vision
ALV
HiSS
nawigacja robotów
Opis:
In this paper, we present an optimization mechanism for two popular landmark-based mobile robot visual homing algorithms (ALV and HiSS), called vector pre-assigned mechanism (VPM). VPM contains two branches, both of which can promote the homing performance effectively. In addition, to make the landmark distribution satisfy the equal distance assumption, a landmark optimization strategy is proposed based on imaging principle of the panoramic vision. Experiments on both panoramic image database and a real mobile robot have confirmed the effectiveness of the proposed methods.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2019, 67, 2; 213-227
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimal quasi-periodic preventive maintenance policies for a repairable system with stochastic maintenance interval
Optymalna strategia quasi-okresowej konserwacji zapobiegawczej systemu naprawialnego – czas między przeglądami jako wielkość stochastyczna
Autorzy:
Gao, W.
Zhang, Z.
Ji, H.
Zhou, Y.
Liu, Q.
Powiązania:
https://bibliotekanauki.pl/articles/301503.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Polskie Naukowo-Techniczne Towarzystwo Eksploatacyjne PAN
Tematy:
maintenance
quasi-periodic imperfect preventive maintenance policy
implemented period
stochastic preventive maintenance interval
konserwacja
strategia quasi-okresowej niepełnej konserwacji zapobiegawczej
dopuszczalny okres realizacji przeglądu
czas między przeglądami jako wielkość stochastyczna
Opis:
The usual preventive maintenance (PM) of a repairable system is done before failure at integer multiples of time T. In some real cases, PM cannot be performed as soon as a planned PM period is reached because of effects of some random factors, while it is usually done within an implemented period, and thus it makes the PM period become a stochastic interval. From this viewpoint, a quasi-periodic imperfect preventive maintenance policy is proposed in this paper, in which a repairable system experiences either a minor failure or catastrophic failure when a failure occurs, and the first (N-1) PM intervals is divided into a planned PM period and an implemented period. In the former, the system may be suffered an unplanned PM for removing a catastrophic failure and performing a PM, whereas in the latter, the system is preventively maintained following an occurrence of a catastrophic failure or a dynamic PM plan, whichever comes first. At the Nth PM interval, the system is replaced either when a catastrophic failure occurs or operational time reaches T, whichever comes first. An optimization of the proposed mode is introduced, the existence and the uniqueness of the optimal solution are presented, and a useful constraint of the implemented period is obtained. Finally, a real case study of PM on Chinese diesel locomotives is examined to illustrate the proposed maintenance policy.
Zazwyczaj przeglądy okresowe systemu naprawialnego wykonuje się przed wystąpieniem uszkodzenia, w określonych odstępach czasu stanowiących całkowitą wielokrotność czasu T. W warunkach rzeczywistych, jednak, nie zawsze można przeprowadzić przegląd w zaplanowanym terminie ze względu na działanie pewnych losowych czynników, natomiast zazwyczaj przeprowadza się go w dopuszczalnym okresie realizacji, w związku z czym przedział czasu między przeglądami okresowymi staje się wielkością stochastyczną. Biorąc powyższe pod uwagę, w niniejszej pracy zaproponowano strategię quasi-okresowej konserwacji zapobiegawczej, która zakłada, że system naprawialny może ulec albo drobnemu uszkodzeniu albo uszkodzeniu katastroficznemu, a czas, do którego należy wykonać pierwszy przegląd okresowy (N-1) można podzielić na zaplanowany czas przeprowadzenia przeglądu oraz dopuszczalny okres realizacji przeglądu. W pierwszym przypadku, może wystąpić konieczność przeprowadzenia nieplanowanej konserwacji systemu mającej na celu usunięcie uszkodzenia katastroficznego, natomiast w drugim, konserwację przeprowadza się po wystąpieniu uszkodzenia katastroficznego lub zgodnie z dynamicznym harmonogramem przeglądów, zależnie od tego, która z sytuacji zaistnieje wcześniej. W N-tym terminie przeglądu okresowego, dokonuje się wymiany systemu, albo wskutek wystąpienia uszkodzenia katastroficznego albo gdy czas pracy systemu osiągnie wartość T, zależnie od tego, co nastąpi wcześniej. W artykule przedstawiono optymalizację proponowanego trybu działania, wykazano istnienie i jednoznaczność optymalnego rozwiązania oraz wyznaczono przydatne ograniczenie dopuszczalnego okresu realizacji. Na koniec, proponowaną politykę konserwacji zapobiegawczej zilustrowano studium przypadku chińskich lokomotyw spalinowych.
Źródło:
Eksploatacja i Niezawodność; 2015, 17, 3; 389-397
1507-2711
Pojawia się w:
Eksploatacja i Niezawodność
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
System for Calibrating Analogue Merging Units in Absence of Synchronization Signals
Autorzy:
Cheng, H.-M.
Huang, Q.-F.
Ji, F.
Xu, Q.
Liu, J.
Tian, Z.
Powiązania:
https://bibliotekanauki.pl/articles/221084.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
intelligent substation
analogue merging unit
peer-to-peer communication
calibration system
synchronization signal
Opis:
Synchronization signals are requisite for calibrating electrical measurement devices with digital output when using conventional calibration methods. However, since the signal sampling process of the analogue merging units (MUs) operating in an intelligent substation does not rely on external synchronization signals, accuracy calibration without the use of synchronization signals is of particular importance in order to guarantee the measurement accuracy in practical situations. So far, very little research on calibration systems independent of synchronization signals has been performed. This paper presents a design of the calibration system without dependence on synchronization signals. To verify the feasibility of the proposed design, the designed system and a conventional calibration system have been employed in testing the accuracy of the same analogue MU of a 0.2 accuracy class. The comparison of the test results shows that the differences of ratio errors are below 0.02%, and the maximum difference of phase errors is about 4′. This paper also provides a new efficient and significant calibration method which does not require any external synchronization signals.
Źródło:
Metrology and Measurement Systems; 2018, 25, 1; 129-138
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Bending, Impact Fracture Behavior and Characteristics of Stainless Steel Clad Plates with Different Rolling Temperature
Autorzy:
An, Q.
Fan, K. Y.
Ge, Y. F.
Liu, B. X.
He, J.
Wang, S.
Chen, C. X.
Ji, P. G.
Tolochko, O.
Powiązania:
https://bibliotekanauki.pl/articles/2049433.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
stainless steel clad plate
interface characteristics
bending behavior
impact morphologies
delamination crack
Opis:
The interface characteristics, bending and impact behavior, as well as fracture characteristics of stainless steel clad plates fabricated by vacuum hot rolling at different rolling temperatures of 1100°C, 1200°C and 1300°C are investigated in detail. The interface bonding strength is gradually increased with the increasing rolling temperature due to the sufficient diffusion behavior of alloy element. The bending toughness and impact toughness are gradually decreased, while the bending strength increase with the increase of the rolling temperature, which is attributed to mechanisms of matrix softening and interface strengthening at high rolling temperature. Due to the weak interface at 1100°C, the bending and impact crack propagation path was displaced by delamination cracks, which in turn lead to reduction in stress intensity of the main crack, playing an effective role in toughening the stainless steel clad plates. Moreover, the impact fracture morphologies of clad plates show a typical ductile-brittle transition phenomenon, which is attributed to the matrix softening behavior with the increasing rolling temperature.
Źródło:
Archives of Metallurgy and Materials; 2021, 66, 1; 229-239
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-10 z 10

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