Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 22

Liczba wyników na stronie
first rewind previous Strona / 2 next fast forward last
Wyniki wyszukiwania
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 2 next fast forward last
EN
In this manuscript, some fixed point results for fuzzy mappings with rational type contraction in the context of a complete partially ordered complex-valued metric space are established. The derived results generalize some fixed point theorems in the existing literature. An appropriate example is given.
EN
Large scaled projects are conducted in South Yellow Sea in recent years. Topographic effect and tidal current are key issues to the coastal engineering and the ocean engineering. In this study, field surveys were conducted to investigate the tidal level, current velocity, and current direction in South Yellow Sea. A numerical model was developed to simulate the radial current field based on the field data. To investigate the mechanism of the radial current field, the actual topography and a smoothed topography were applied in the numerical model, respectively. Results show that, the current field appeares radial because of the tidal system rather than the submarine topography. Local topography centralized the radiation centre and shifted the high-velocity zones. The actual topographic effect is proposed, and results show that local topography increases the flood tide velocity and decreases the ebb tide velocity. Lagrangian residual currents are calculated to illustrate possible sediment sources and transport routes.
EN
In this work, two collectors sodium oleate (NaOL) and benzohydroxamic acid (BHA) were used to study the synergic effect in wolframite flotation. The flotation behaviour of these collectors was investigated at various NaOL:BHA ratios. Results show that the mixtures of NaOL with BHA of different ratios result in large improvements in the recovery of wolframite and the 9:1 NaOL:BHA ratio of collector mixture produced the highest wolframite recovery. The amount of NaOL and BHA adsorbed on wolframite was measured for these various reagent mixtures. Compared with pure NaOL, the addition of a certain proportion of BHA is beneficial for NaOL adsorption. Molecular dynamics simulations indicate the formation of HOL–HA (oleic acid–benzohydroxamic acid) complex can take place spontaneously in NaOL–BHA system. Additionally, HOL–HA complex interact with the huebnerite (MnWO4) surface more easily than NaOL–HOL (the highest surface active composition in sodium oleate) and the addition of BHA enable the H of carboxyl group in HOL to generate hydrogen bonds with O atoms of huebnerite surface, resulting in a stronger affinity of mixed surfactants. These results reveal that in a binary NaOL–BHA system, the BHA can encourage greater adsorption of the NaOL.
EN
Planktonic ciliate composition, abundance and its response to environmental change were investigated during four seasons (winter of 2013, spring, summer and autumn of 2014) in Daya Bay, the South China Sea. A total of 41 species belonging to eight orders were identified, 14 of which were dominant. Planktonic ciliate communities showed a distinct seasonal pattern in ciliate abundance and a clear seasonal shift in the taxonomic composition. The largest number of ciliate species occurred in summer, whereas the highest abundance peaked in spring, mainly due to oligotrichids. In terms of spatial distribution, ciliate species were abundant in the area of artificial reefs, and ciliate abundance was higher in the Dapeng Cove aquaculture area and lower at the Daya Bay Nuclear Power Station. Clustering analysis demonstrated that the seasonal variations of the ciliate community structure were more obvious than spatial variations. Multivariate and univariate analyses illustrated that ciliate abundance was significantly correlated with the water nutrient level and chlorophyll-a concentration, temperature, salinity and dissolved oxygen. Moreover, the dominant abiotic environmental factors affecting the spatial pattern of ciliate communities varied between seasons.
EN
Improving the accuracy of forecasting is crucial but complex in the clothing industry, especially for new products, with the lack of historical data and a wide range of factors affecting demand. Previous studies more concentrate on sales forecasting rather than demand forecasting, and the variables affecting demand remained to be optimized. In this study, a two-stage intelligent retail forecasting system is designed for new clothing products. In the first stage, demand is estimated with original sales data considering stock-out. The adaptive neuro fuzzy inference system (ANFIS) is introduced into the second stage to forecast demand. Meanwhile a data selection process is presented due to the limited data of new products. The empirical data are from a Canadian fast-fashion company. The results reveal the relationship between demand and sales, demonstrate the necessity of integrating the demand estimation process into a forecasting system, and show that the ANFIS-based forecasting system outperforms the traditional ANN technique.
PL
Poprawa dokładności prognozowania jest bardzo istotna, ale skomplikowana w przypadku przemysłu odzieżowego, zwłaszcza dla nowych produktów oraz szerokiego zakresu czynników wpływających na popyt. Wcześniejsze badania bardziej koncentrowały się na prognozowaniu sprzedaży, niż prognozowaniu popytu. Zmienne wpływające na popyt powinny zostać zoptymalizowane. W tym badaniu opracowano dwustopniowy inteligentny system prognozowania sprzedaży detalicznej przeznaczony dla nowych produktów odzieżowych. W pierwszym etapie, popyt jest określony za pośrednictwem oryginalnych danych dotyczących sprzedaży. Adaptacyjny neuronowy system danych rozproszonych (ANFIS) jest wprowadzony w drugim etapie do prognozowania popytu. Jednocześnie prezentowany jest proces selekcji danych. Dane empiryczne pochodzą z kanadyjskiej firmy.
EN
Rockburst is divided into two types, one is strain-type resulting from rock damage and another is sliding-type resulting from fault slip events. Triggering mine pillar rockburst mainly consists of two steps: the occurrence of shear-band and the application of disturbance. In this paper, mechanical model of mine pillar subjected to uniaxial compression is established. By simplifying the complete stress-strain curve and the crack propagation behaviour, based on the derived energy expressions corresponding to different crack propagation stages, the type of rockburst that the disturbance-induced pillar instability belongs to is defined. Next, by establishing the model of mine pillar with one inclined shear-band and by simplifying the stress evolution on the band, based on the necessary physical characteristics for triggering dynamic events, the basic mechanical property of mine pillar required for triggering instability is derived. It shows that the post-peak modulus greater than or equal to the pre-peak modulus is the basic mechanical property required for triggering mine pillar instability. Finally, by conducting laboratory experiments, the proposed model is verified. The requirement that the post-peak modulus is greater than or equal to the pre-peak modulus may be the rea-son why triggered mine pillar rockburst is not often observed.
EN
In this paper, the micro-cracks in the brittle rocks are assumed to be penny shaped and evenly distributed; the damage and dilatancy of the brittle rocks is attributed to the growth and expansion of numerous micro-cracks under the local tensile stress. A single crack’s behaviour under the local tensile stress is generalized to all cracks based on the distributed damage mechanics. The relationship between the local tensile stress and the external loading is derived based on the Maxwell model. The damage factor corresponding to the external loading is represented using thep–alpha (p–α) model. A dilatancy equation that can build up a link between the external loading and the rock dilatancy is established. A test of dilatancy of a brittle rock under triaxial compression is conducted; the comparison between experimental results and our theoretical results shows good consistency.
EN
Using the density matrix theory, we have studied the double tunneling induced transparency slow light in the double asymmetry quantum dot molecules. With applied electric field, double tunneling induced transparency occur in the same time. Four absorption peaks are found near the resonance energy level in the absorption spectrum and the absorption peak can be tuned by the applied electric field. The velocity and bandwidth of the multiple-windows slow light can also be controlled by the applied electric field. In our model, with Te =0.1meV, we can get about 0.001c and 20GHz bandwidth in each transparency window. Such a property may be applied in all optical buffers, optical switching and filter.
EN
The ε→γ phase transition of HNIW induced by heat was investigated with in situ X-ray powder diffraction (PXRD). The effects of purity, particle size, insensitive additives and the time of isothermal heat treatment on the phase transition were evaluated. It was found that the phase transition is irreversible with changes in temperature, and the two phases can coexist in a certain temperature range. Moreover, the initial phase transition temperature increases with increasing purity and decreasing particle size of HNIW, and thus with the approximate crystal density. The addition of graphite and paraffin wax to HNIW as insensitive additives leads to a decrease in the initial phase transition temperature, but the addition of TATB does not affect the initial phase transition temperature. Thus, TATB is a suitable insensitive additive. Moreover, at the critical temperature, the isothermal time determined the efficiency of the ε- to γ-phase transition. This work lays the foundations for the choice of molding technologies, performance test methods, ammunition storage options, as well as the manufacture of HNIW-based explosive formulations.
EN
Rock is a typical inhomogeneous material with a large number of flaws in different scales; the stress field of the rock in its elastic state consists of two parts: the elastic stress, which distributes uniformly in the entire region; and an additional stress, which only exists around the flaws. Theoretical expressions of the additional stress and local stress are derived based on the Maxwell model. Core disking which takes place under the condition that the axial stress is rapidly reduced while the confining pressure is kept unchanged is explained with a new method. Unloading duration’s effect on core disking is analyzed. A new criterion for core disking is presented based on attributing the core disking to the result of the exceedance of local tensile stress over the tensile strength. Based on our theoretical analysis and the conclusions from published resources, core disking is most likely to occur if the maximum principal stress is more than five to six times the tensile strength.
EN
A rapid and sensitive method for the identification and quantification of phillyrin (POG) in Forsythia suspense is described. The phillyrin standard solution was directly infused into the ion trap mass spectrometers (IT-MS) for collecting the MSn spectra. The electrospray ionization (ESI) mass spectral fragmentation pathway of phillyrin was proposed, and the ESI-MSn fragmentation behavior of phillyrin was deduced in detail. The major product ion at m/z 355 belongs to furofuran, which was formed by loss the glucopyranoside (180 Da), and the characteristic fragment ions m/z 473, 395, 337, 309, and 249 were observed. The loss of 18 Da could arise from two different fragmentation pathways, and the observed ion was composed of a mixture of two different structural ions. Quantification of phillyrin was assigned in positive-ion mode at a product ion at m/z 557 → 355 by liquid chromatography-mass spectrometry (LC-MS). The LC-MS method was validated for linearity, sensitivity, accuracy, and precision and then used to determine the content of the phillyrin. Lastly, the LC-MS method was successfully applied to determine phillyrin in real sample F. suspense and three of its medicinal preparations in the positive mode at the first time.
EN
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.
EN
Most primary explosives are non-conductors, easily accumulate charge when contacting with and separating from other materials, and are sensitive to electrostatic discharge (ESD). In order to reduce the number of accidents caused by ESD initiation of primary explosives, studies on their electrostatic hazards are necessary. This work presents comprehensive experimental results of electrostatic discharge sensitivity and chargeability of tris(carbohydrazide)zinc perchlorate (ZnCP) under different conditions. The influences of the testing conditions, of devices, particle size, ambient temperature and relative humidity on the electrostatic discharge sensitivity and chargeability have been investigated in detail, and the quantitative regression equations obtained.
14
Content available remote Experimental study on fatigue damage of train K6 spring
EN
Springs’ fatigue life and damage are key evaluation parameters for railway train bogies. Fatigue experiment on K6 bogie spring is carried out by digital display hydraulic pulse fatigue test device. Spring fatigue life is estimated by using nominal stress method. Based on the technology of ultrasound nondestructive test device, the relationship between accumulation of internal fatigue damage and cycle loading times is obtained. The results indicate that same batches of K6 springs have high reliability; spring material internal fatigue damage increases as cycle loading times.
PL
W artykule przedstawiono wyniki badań dotyczących zmęczenia sprężyn w podwoziach wagonowych. Analizie, przy pomocy hydraulicznego urządzenia testującego poddano sprężynę wagonową typu K6. Korzystając z badań ultradźwiękowych określono związek między tworzeniem się skupisk uszkodzeń wewnętrznych a cyklicznym obciążaniem.
EN
A single crystal of iron (II) carbohydrazide perchlorate [FeII (CHZ)3](ClO4)2 (FeCP), a novel, lead-free, energetic coordination compound, was synthesized and its structure determined by X-ray single crystal diffraction for the frst time. The crystal belongs to the monoclinic system P2(1)/n space group, with a = 1.0066(2) nm, b = 0.8458(2) nm, c = 2.1194(4) nm, β = 100.693(3)° and Z = 4. The central Fe(II) ion is coordinated to three bidentate carbohydrazide units through the carbonyl oxygen atom and an amino nitrogen atom, forming a six-coordinated, non-centrosymmetric complex cation. The thermal analyses by differential scanning calorimetry and thermogravimetry show that the onset temperature of thermal decomposition (152.7 °C) and the critical temperature of thermal explosion of FeCP (161.2 °C) are both much lower than those of other transition metal carbohydrazide perchlorate compounds, and also those of some other primary explosives in service. FeCP has a high enthalpy of combustion, as measured by oxygen bomb calorimetry. The impact, friction and fame sensitivity tests indicate that FeCP is extremely sensitive and hazardous. Unexpected explosions occurred even during the operational processes. In order to explore the intrinsic cause of these explosions, theoretical calculations of the orbital energies were performed based on DTF. These results reveal that the impact sensitivity is positively correlated with the energy gap between HOMO and LUMO: the smaller energy gap results in the higher impact sensitivity.
16
Content available remote Natural disaster hidden danger recognition decision support system for coal mine
EN
Safety accidents caused by pit natural disasters affect operation and economic benefits of coal mine seriously. Against types of Coal mine natural disasters, occur regulation and workflow models of coal mine safety management, the concepts, architecture, construction principles, key theory and methods and techniques of Pit Hidden Danger Recognition Decision Support System model were proposed, based on geography information system, management information system and cooperative work theory and so on.
PL
Incydenty bezpieczeństwa spowodowane przez klęski żywiołowe kopalnii mocno wpływają na bezpieczną produkcję i efektywność ekonomiczną. Uwzględniając rodzaje i prawidłowości występowania klęski żywiołowej w kopalni zaproponowano koncepcję i model systemu wspomagania decyzji.
EN
Feature words are crucial clues for word sense disambiguation. There are two methods to select feature words: window-based and dependency-based methods. Both of them have some shortcomings, such as irrelevant noise words or paucity of feature words. In order to solve the problems of the existing methods, this paper proposes two methods to select feature words with syntactic parsing, which are based on phrase structure parsing tree (PTree) and dependency parsing tree (DTree). With the help of syntactic parsing, the proposed methods can select feature words more accurately, which can alleviate the effect of noise words of window-based method and can avoid the paucity of feature words of dependency-based method. Evaluation is performed on a knowledge-based WSD system with a publicly available lexical sample dataset. The results show that both of the proposed methods are superior to window-based and dependency-based methods, and the method based on PTree is better than the method based on DTree. Both of them are preferred strategies to select feature words to disambiguate ambiguous words.
PL
W artykule zaproponowano dwie metody selekcji cech słowa bazujące na analizie składni struktury frazy oraz analizie składni zależności. Badania przeprowadzono przy wykorzystaniu rożnych baz danych. Proponowana metoda ma większą dokładność niż dotychczas stosowane metody: okna i zależności.
EN
Starting strategies were investigated for a three-phase single-stage power factor correction (PFC) convetter. Starting process and mechanism of input over current was analyzed in detail. A lossy method was proposed and designed in which a resistor was connected in series with the filter capacitor to increase effective value of output voltage. Based on them, the boost inductors were replaced by central-tapped inductors with flyback windings, and a lossless starting strategy was proposed. Experimental results prove the validity and feasibility of the proposed methods.
PL
Przeanalizowano strategie startu trójfazowego przekształtnika do korekcji współczynnika mocy PFC. Zaproponowano metodę w której rezystor połączony jest szeregowo z pojemnością filtru w celu zwiększenia napięcia wyjściowego. Cewka została zastąpiona cewką z zaczepami umożliwiającej zmianę uzwojeń. Zaproponowano bezstratną strategię startu.
EN
Molecular techniques were employed to document the microbial diversity associated with the marine sponge Pachychalina sp. from South China Sea in March 2003. Using the total microbial DNA as template, bacterial and archaeal 16S rDNAs were amplified by PCR with universal primers. Amplified products were cloned, sequenced and secondarily amplified by PCR. Then the secondarily amplified products were purified to be further characterized by amplified rDNA restriction analysis (ARDRA). According to the enzyme restriction mapping, the apparent difference among them were disclosed. 22 bacterial cloned partial sequences were acquired and most of them were related to proteobacterium. Also, 7 archaeal cloned partial sequences were acquired and a phylogenetic tree was built up.Result shows the prolific bacterial and archaeal diversity of marine sponge Pachychalina sp.
EN
Abstract A hydrodynamics + hadronic rescattering model is used to simulate Au+Au collisions at 200 GeV and a Cooper-Frye method is adopted for hadronization. The effect of hadronic rescattering on elliptic flow V2 in 20 40% Au+Au collisions at 200 GeV has been investigated. It is found that the hadronic rescattering can suppress elliptic flow V2 and makes an asymmetric system in momentum space tend to be less anisotropic. The suppression effect becomes weak with increasing transverse momentum. In addition, the effect of hadronic rescattering on transverse momentum spectra and anisotropy of hadronic coordinate space is presented.
first rewind previous Strona / 2 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.