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EN
A plate-cavity coupling method based on modal expansion technique in the closed sound cavity was introduced, aiming at ship cabin structural noise. Using this method, a coupled equation was established. The structural vibration acceleration of the target cabin was extracted from a ship vibration response calculation, applied to the model. Then the target cabin noise value was obtained through numerical calculation. The effectiveness and reliability of the method were validated through experiments. The coupled model predicts noise in the cabin does not require fluid finite element model of the cabin air, thus greatly reducing the calculation time compared with the pure finite element method. It was shown that the method is suitable for the calculation of noise in a single ship cabin; the method has a high calculation efficiency. Furthermore, the calculated result is a continuum. On the one hand, it can be conveniently converted to an octave or 1/3 octave according to the specification. On the other hand, the form of the continuum also provides a corresponding response to the subsequent vibration and noise control.
EN
The health condition of rolling bearing can directly influence to the efficiency and lifecycle of rotating machinery, thus monitoring and diagnosing the faults of rolling bearing is of great importance. Unfortunately, vibration signals of rolling bearing are usually overwhelmed by external noise, so the fault frequencies of rolling bearing cannot be readily obtained. In this paper, an improved feature extraction method called IMFs_PE, which combines the multivariate empirical mode decomposition with the permutation entropy, is proposed to extract fault frequencies from the noisy bearing vibration signals. First, the raw bearing vibration signals are filtered by an optimal band-pass filter determined by SK to remove the irrelative noise which is not in the same frequency band of fault frequencies. Then the filtered signals are processed by the IMFs_PE to get rid of the relative noise which is in the same frequency band of fault frequencies. Finally, a frequency domain condition indicator FFR(Fault Frequency Ratio), which measures the magnitude of fault frequencies in frequency domain, is calculated to compare the effectiveness of the feature extraction methods. The feature extraction method proposed in this paper has advantages of removing both irrelative noise and relative noise over other feature extraction methods. The effectiveness of the proposed method is validated by simulated and experimental bearing signals. And the results are shown that the proposed method outperforms other state of the art algorithms with regards to fault feature extraction of rolling bearing.
EN
Some physical aspects of Chinese cuisine are discussed. We start from the cultural and historical particularities of Chinese cuisine and their food production technologies. What is the difference between raw and boiled meat? What is the difference in the physical processes of heat transfer during either the steaming of dumplings or during cooking them in boiling water? Why is it possible to cook meat stripes in a "hot pot" in ten seconds, whilst baking a turkey requires several hours? This article is devoted to a discussion of these questions.
PL
W artykule zostały przedyskutowane niektóre aspekty kuchni chińskiej. Autorzy zaczynają od omówienia szczegółów kuchni chińskiej i technologii produkcji żywności. Autorzy zadają następujące pytania: jaka jest różnica pomiędzy mięsem surowym a gotowanym? Jaka jest różnica w fizyce procesu przenoszenia ciepła podczas przyrządzania klusków na parze wodnej a w gotującej się wodzie? Dla czego jest możliwe przyrządzanie kawałków mięsa w "gorącym garnku" w ciągu kilku sekund, podczas gdy po to, aby upiec indyka potrzebujemy kilku godzin? Artykuł ten udziela odpowiedzi na te i inne pytania.
EN
A new image encryption algorithm by using a discrete fractional angular transform and Arnold transform in image bit planes is investigated. In the image encryption algorithm, the original image is encrypted by the Arnold transform in image bit planes firstly, and then the resulting image is encrypted by the discrete fractional angular transform further. The key of the image encryption algorithm includes the parameters of the Arnold transform and the order of the discrete fractional angular transform. It is shown that the proposed image encryption algorithm is of high security and strong enough to counteract some conventional image attack manners.
EN
Under the bad sea conditions and weak Beidou navigation signal environment, it is difficult to locate the ship on the sea, and the Beidou navigation system can’t work well. Beidou pseudolite system can improve the performance of Beidou navigation system as a navigation signal transmitter fixed on the ground, the signal of which can improve satellite positioning constellation structure, and improve the system availability reliability and precision. In order to ensure the interoperability and non-correlation of the Beidou pseudolite and the Beidou navigation system, the pseudolite ranging-codes should be selected in the same code space of the satellite ranging-codes and the residual pseudo random code generated by the 2 taps design scheme does not satisfy the performance requirements of the ranging-codes. To solve this issue, a combined design scheme with 3 taps is proposed, and 12 kinds of pseudolite ranging-codes are optimally selected according to the optimum design parameters of ranging-codes. The waveform and correlation of the selected pseudolite ranging-codes are analyzed by MATLAB, the acquisition simulation is carried out by using the new pseudolite ranging-codes. The experimental results show that the new 3-taps based ranging codes design scheme behaves a good balance, correlation and spectral characteristics.
EN
A new image encryption scheme based on logistic map and discrete fractional angular transform has been proposed. In the proposed scheme, the original image is encrypted with the random sequence generated by the logistic map, and the encrypted image is subsequently processed by the discrete fractional angular transform, which produces the ciphertext after double encryptions. The parameters of the logistic map and the order of the discrete fractional angular transform serve as the main keys of the image encryption algorithm. Simulation results show that the proposed image encryption algorithm can effectively resist the attacks of statistical analysis, and has acceptable encryption effect and security.
EN
The influence of the surface metal fiber (SMF) arrangement on the shielding effectiveness (SE) of electromagnetic shielding fabric (EMSF) is important, but there is no reasonable description method for it at present, making the further exploration of the relationship between SMF and SE difficult. In order to scientifically describe the SMF arrangement of EMSF, this paper constructs a binary feature matrix of SMF based on a previous study of SMF region recognition. According to the feature matrix, three parameters of the exposure ratio, the discrete mean and disorder degree are proposed and the calculation equations for the three parameters given. Experiments were designed and testing samples determined to test the SE, and the exposure ratio, discrete mean and disorder degree of each sample are calculated. The relationship between the three parameters and the SE is analysed for effectiveness validation of the three parameters. Results show that the exposure ratio, discrete mean and disorder degree can describe three aspects of the SMF arrangement: the percentage content, porosity and orientation, which are positively correlated, negatively correlated and positively correlated to the SE, respectively. The research in this paper provides a basis for the study of the shielding mechanism, the transmission model, the shielding rule and the rapid non-destructive evaluation of the EMSF, and puts forward a new idea for the study of shielding theory and the application of the EMSF.
PL
Ze względu na istotny wpływ rozmieszczenia włókien metalowych (SMF) na skuteczność ekranowania (SE) tkanin osłonowych (EMSF) w pracy przedstawiono macierz binarną opartą na trzech parametrach włókien metalowych tj.: współczynniku ekspozycji, średniej wartości odległości między włóknami metalowymi i stopniu ich nieuporządkowania. Analizowano zależności pomiędzy wyżej wymienionymi parametrami a skutecznością ekranowania. Przedstawione wyniki stanowią podstawę do opracowania szybkiej i nieniszczącej metody oceny skuteczność ekranowania oraz do dalszych badań mechanizmu ekranowania.
EN
As a form of urban green space, community gardens have provided urban residents with various environments, to satisfy their social, economic and health interests. For the purposes of creating public, open and shared spaces, this article summarizes and contrasts the history of the community garden development in Europe and America, while analyzing the development situation of China as well. Taking “the Kid’s Garden” in Hunan Agricultural University as an example, the authors discuss the whole practice process in three aspects: the layout design, the construction process, and the operation and maintenance plan. Finally, the conclusion of the article presents a community garden building model, which is supported by universities with the goals to reward the society, as well as to provide a win-win result between practice and teaching. This experience is hoped to popularize community gardens and to make a contribution towards a harmonious society.
EN
Heavy metal contamination due to mining activity is a global major concern because of its potential health risks to local inhabitants. The heavy metal contamination of surface water and ground water by mining activities in Gejiu tin-polymetallic mining area, Southwest China, was studied. Surface water and ground water were sampled and analyzed using AAS for Cr6+, Cd, As, Hg, Cu, Pb, Zn, Se, Fe and Mn. Analysis of HCO3–, Cl–, SO42–, F– and NO3– in water samples was also undertaken by ion chromatography. It was shown that none of water samples exceeded the guideline of Cr6+, Se and Hg, while the contamination degree of heavy metals was Mn > Fe > Cd > Zn > Pb > As > Cu, all of which were serious contamination except mild contamination for Cu. The ground waters were polluted much worse than surface water.
PL
Zanieczyszczenie metalami ciężkimi spowodowane działalnością kopalń jest światowym problemem z powodu ryzyka utraty zdrowia przez okolicznych mieszkańców. Zbadano zanieczyszczenie wód powierzchniowych oraz wód podziemnych wywołane działalnością kopalni cyny w rejonie górniczym Gejiu, południowo-zachodnie Chiny. Pobrano próbki wody powierzchniowej oraz podziemnej i zanalizowano je ze względu na obecność Cd, As, Hg, Cu, Pb, Zn, Se, Fe oraz Mn. Analizy HCO3–, Cl–, SO42–, F– oraz NO3– w próbkach wody również zostały przeprowadzone za pomocą chromatografii jonowej. Ukazano, że żadna z badanych wód nie przekroczyła dopuszczalnych poziomów dla Cr6+, Se oraz Hg. Jednakże poziom zanieczyszczenia metali ciężkimi tj. Mn > Fe > Cd > Zn > Pb > As > Cu był wysoki, za wyjątkiem niewielkiego przekroczenia norm dla Cu. Wody podziemne były znacznie bardziej zanieczyszczone niż wody powierzchniowe.
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.
11
Content available remote Geological defect and its geophysical prediction method in Karst Tunel
EN
With the rapid development of traffic tunnels construction in mountain area in the world, hydrogeological conditions are becoming unprecedentedly complex, water inrush and mud gushing is one of the typical common geologic hazards for the karst tunnel construction. .Based on the analyzing karst tunnel water inrush examples in recent years in china, the mechanism of geologic structure for water inrush has been explained through analyzing different karst hydrogeological storage structures. The unfavorable geologic bodies can be forecasted by geophysical method, and the detecting device and the signal receiving sensor would be selected for different water-bearing structure. The seismic wave, electromagnetic wave will be reflected and received by sensor when encountered geological defect, and the attributes of unfavorable geologic bodies were identified based on the returned signal. Risk assessment of water inrush must be done firstly during tunnel construction, an optimal system for water-bearing structure detecting in which prediction methods vary with the risk level of water inrush can be probed. As a result, the hazard prevention & controlling technological system of water inrush of karst tunnel is composed of risk evaluation system and comprehensive geological prediction system. It has been successfully used for hazards prevention and control for water inrush of Qiyueshan Tunnel in Hurong highway, including risk assessment and hazard source detection. Conclusions will benefit further research on hazards control of underground construction.
PL
Wraz z szybkim rozwojem budowy tuneli w terenach górskich rośnie znaczenie oceny warunków hydrogeologicznych: W szczególności, w przypadku tuneli w terenach krasowych, typowym niebezpieczeństwem jest napór wody i tryskające błoto. Na podstawie analizy wypadków w tunelach krasowych w Chinach w ostatnich latach, wyjaśniono mechanizm naporu wody przez analizę różnych formacji hydrogeologicznych w obszarach krasowych. Niekorzystne warunki geologiczne można prognozować metodami geofizycznymi, przez zastosowanie urządzenia detekcji sygnałów odbitych od różnych struktur wodonośnych. Podczas projektowania tunelu należy ocenić ryzyko wystąpienia naporu wody i przeprowadzić wszechstronną prognozę geologiczną. Przy budowie tunelu Qiyushan linii kolejowej Hurong przeprowadzono badania obejmujące oszacowanie ryzyka i wskazano źródła niebezpieczeństw.
12
EN
This study proposes an equivalent metal shield model in order to solve shielding effectiveness (SE) computation of electromagnetic shielding (EMS) blended fabric. The equivalent metal shield consisting of metal fiber is constructed according to the metal fiber content per unit volume of the EMS fabric, and a computation method for the thickness of the equivalent metal shield is given. Then a SE computation of EMS fabric based on the equivalent metal shield model is established. An equivalent coefficient of the SE computation of plain, twill and satin weave fabric is determined by experiments. Results and analyses show that the relative errors of the proposed computations are low and the computations and evaluations are satisfied for the normal EMS blended fabrics.
PL
W artykule przedstawiono sposób modelowania ekranu metalowego, na potrzeby obliczeń numerycznych efektywności ekranowania tkaniny mieszanej, zawierającej włókna metalowe. Wyznaczono współczynnik efektywności ekranowania w zależności od rodzaju zastosowanej tkaniny. Wyniki analiz i obliczeń błędów względnych wykazały, że wyznaczone wielkości są niewielkie i satysfakcjonujące dla typowych tkanin mieszanych.
EN
Temporal variation is a major source of the uncertainty in estimating the fluxes of the greenhouse gases (GHGs) in terrestrial ecosystems, and the GHG fluxes and its affecting factors in the karst region of southwest China remains weakly understood. Using the static chamber technique and gas chromatography method, the CO2, CH4 and N2O fluxes were carried out between 9 and 11 a.m. at 15 day intervals from June 2008 to May 2009 in a Pinus massoniana forest. Two treatments were chosen for this study: undisturbed (soil with litter layer) and disturbed (surface litter removal). Both treatments were found to be the net source of atmospheric CO2 and N2O, but a sink of atmospheric CH4. The seasonality of soil CO2 emission coincided with the seasonal climate pattern, with high CO2 emission rates in the hot-wet season and low rates in the cool-dry season. In contrast, seasonal patterns of CH4 and N2O fluxes were not clear, although higher CH4 uptake rates were often observed in autumn and higher N2O emission rates were often observed in spring (dry-wet season transition). The litter was active in GHG fluxes, and removal of the litter layer reduced soil CO2 emission (17%) and increased CH4 uptake (24%) whereas N2O fluxes were not affected distinctly in the pine forest, indicating that litter layer had an important effect on C exchanges. In the pine forest, soil CO2 emissions and CH4 uptakes correlated significantly with soil temperature (r2 = 0.87, P <0.01; r2 = 0.34, P <0.05, respectively), but had no significant relationship with soil moisture. And there was a significant correlation between CH4 flux and NH4+-N (r2 = 0.39, P < 0.05) and soil inorganic N (r2 = 0.48, P <0.05), but no significant correlation was found between CH4 flux and NO3--N. Moreover, we found a significant negative logarithmic correlation between N2O flux and soil NO3--N concentration (r2 = 0.41, P <0.05), and the relationship between CO2 emission and soil inorganic N content (r2 = 0.35, P < 0.05). These results suggested that soil temperature and mineral N dynamics largely affected the temporal GHG exchanges between forest soil and atmosphere.
EN
A model to optimize the planning of the chemical integrated system comprised by multi-devices and multi-products has been proposed in this paper. With the objective to make more profits, the traditional model for optimizing production planning has been proposed. The price of chemicals, the market demand, and the production capacity have been considered as mutative variables, then an improved model in which some parameters are not constant has been developed and a new method to solve the grey linear programming has been proposed. In the grey programming model, the value of credibility can be suggested by the decision-makers, and the results of the production planning calculated by the model can help them to achieve their desired target. An actual case has been studied by the proposed methodology, and the proposed methodology can be popularized to other cases.
EN
The near-field multiple optical trapping using high order axially symmetric polarized beams (ASPBs) is studied for the first time. First, a near-field optical trapping scheme is proposed based on the Kretschmann–Raether configuration, and surface plasmon polaritons (SPPs) field distributions excited by incident ASPBs are calculated, which present a multi-focal-spot pattern and the size of spots is much smaller than that of the diffraction limitation. Then, the gradient forces on Rayleigh dielectric particles formed by the multi-focal-spot focused field are computed, which indicates that multiple ultra-small particles with the refractive index higher than that of the ambient medium can be trapped simultaneously on the metal surface. The number and size of trapped particles can be manipulated by flexibly modifying the polarization order of incident beams, which is expected to enhance the capability of traditional optical trapping systems and provide a solution for massively parallel optical trapping of nanometer-sized particles.
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.
17
Content available remote Analysis of Excitation Current in DC-Biased Transformer by Wavelet Transform
EN
To analyze the excitation current in DC-Biased Transformer in depth, the thesis deduces the mathematical expression of distortion excitation current, and put forwards the analysis method with wavelet transform principle, which directs at analyzing the boundedness of distortion excitation current using the Fourier Transform. Through sampling the distortion excitation current signal, we resolve its wavelet LF approximation signal and HF detail signal, conclude DC component size of the distortion excitation current, confirm the moment of excitation current waveform distorting, comparatively analyze the results after Fourier Transform, and make clear that the principle is feasibility and superiority. Through analyzing the energy spectrogram in the signal high-frequency band of distortion excitation current and short circuit current are determined. Simulation results show that energy changes in the high frequency band among the different scale. In practice, DC bias can lead to the action of relay protection device, which does harm to the system potentially.
PL
Przedstawiono metodę analizy składowej stałej podmagnesowującej w prądzie magnesującym transformatora. Do analizy wykorzystuje się transformatę falkową I transformatę Fouriera prądu magnesującego.
EN
Bioactive glass was supposed as a biodegradable material and designed as a scaffold to be used for bone reconstruction or regeneration. Bioactive glass scaffold with pore sizes ranged in 100-400µm in diameter was fabricated by sol-gel method, and the biocompatibility evaluation of bioactive glass scaffolds was also performed by culture in vitro models. Cells cultured in the extracts of bioactive glass appeared to show normal morphology. The scaffolds supported osteoblast growth and induced differentiation within the 21 day culture period. Confocal laser scanning microscopy (CLSM) demonstrated the normal cell distribution and proliferation on porous biomaterials. Osteoblasts attached and proliferated on the scaffold as demonstrated by scanning electron microscopy (SEM). Nodule formation and multilayer structures were observed on the scaffold surface and in the pores of the glass. The relationship between seeding density and viability of human osteoblasts cultured on the porous bioactive glass were measured.
EN
A new HPLC method has been established for determination of 3-monoiodotyrosine (MIT), 3,5-diiodotyrosine (DIT), 3,5-diiodothyronine (T2), 3,3',5-triiodothyronine (T3), 3,3',5'-triiodothyronine (rT3), and thyroxine (T4) produced by hydrolysis of iodinated casein with barium hydroxide. The hydrolytic stability of each analyte was evaluated. Iodinated casein was hydrolyzed with saturated barium hydroxide solution for 16 h at 110°C and the barium ions were then removed as barium sulfate. Reversed-phase HPLC was performed on a 2.1 mm × 150 mm, 5 µm particle, C 18 column with a mixture of acetonitrile and 0.1% (v/v) formic acid as mobile phase at a flow rate of 0.2 mL min -1. Acetonitrile was maintained at 5% (v/v) for 5 min and then increased linearly to 50% (v/v) within 35 min. All analytes were quantified by measuring the absorbance at 280 nm. Validation data indicated the method was linear, with regression coefficients (R 2) > 0.998, in the concentration ranges investigated. Sensitivity was adequate-limits of detection (LOD) were 0.04-0.38 µg mL -1 and limits of quantification ( LOQ ) were 0.05-0.38 µg mL -1 . Accuracy and precision were acceptable - for all the analytes recovery was 82.0-93.0% and repeatability, as relative standard deviation, was 1.0-3.0%. Hydrolytic stability tests indicated MIT and DIT are much more stable than the other analytes. rT3 was not released directly from iodinated casein but was formed by deiodination of T4 during hydrolysis. The method could be used to identify iodinated casein, to evaluate its activity and quality, and for supervision and regulation of feed additives.
EN
The paper has as an objective to combine and disseminate a brief knowledge on generators and power electronics for Wave Dragon MW (WDMW) Power Take Off system. Wave Dragon MW captures power from sea waves by means of low-head turbines and converts it into rotating mechanical power. In recent years because of energy saving problem on almost whole world power electronics and electric machines as well as renewable energy market has been intensively developed. Problems which can appear in conversion mechanical power to electrical power in WDMW can be expected to be similar as in wind turbine. Therefore, state of the art briefly can base on state of the art for wind turbines. However, subject of the mechanical energy conversion from sea waves to electrical energy is not well identified and further research should be curried out.
PL
Artykuł ma na celu zebranie i przedstawienie podstawowych informacji na temat przekształtnika energii fal morskich Wave Dragon MW (WDMW). Ponadto również wstępne wyniki symulacyjne zespołu generator-przekształtnik energoelektroniczny - sieć.
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