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EN
The current passed by the stator coil of the permanent magnet synchronous motor (PMSM) provides rotating magnetic field, and the number of turns will directly affect the performance of PMSM. In order to analyze its influence on the PMSM performance, a 3 kW, 1500 r/min PMSM is taken as an example, and the 2D transient electromagnetic field model is established. The correctness of the model is verified by comparing the experimental data and calculated data. Firstly, the finite element method (FEM) is used to calculate the electromagnetic field of the PMSM. The performance parameters of the PMSM are obtained. On this basis, the influence of the number of turns on PMSM performance is quantitatively analyzed, including current, no-load back electromotive force (EMF), overload capacity and torque. In addition, the influence of the number of turns on eddy current loss is further studied, and its variation rule is obtained, and the variation mechanism of eddy current loss is revealed. Finally, the temperature field of the PMSM is analyzed by the coupling method of electromagnetic field and temperature field, and the temperature rise law of PMSM is obtained. The analysis of this paper provides reference and practical value for the optimization design of PMSM.
EN
As the main predator and disperser of seeds, rodents play an important role in the process of vegetation regeneration by adopting different foraging and hoarding strategies in forest ecosystems. Infrared automated detection cameras and seed-tagging methods were used to understand the effects of rodents on seeds in natural environments. We chose the dominant species Apodemus peninsulae (Korean field mouse) as the focus of this study, and seeds of the three species Pinus koraiensis, Corylus mandshurica and Quercus mongolica were released and tracked in a temperate forest in northeast China. The results showed that approximately 80% of the seeds were manipulated by A. peninsulae, 15.1% of the seeds were used as food, 20.4% of the seeds were handled after feeding, 41.3% of the seeds were handled during storage, and 23.3% of the seeds remained intact. In addition, A. peninsulae preferred Q. mongolica (85.3%) and P. koraiensis (85.6%) over C. mandshurica (59.2%). The rodents frequently hoarded seeds from every species in many small, close-range, widely dispersed, single scatter-hoarded caches around the seed station. Most caches were dispersed approximately 2-4 m from the seed station. The results indicated that A. peninsulae adopted significant discriminatory processing strategies for predation, consumption, dispersal and hoarding of the different seeds of sympatric species. Seed size, proportion of kernel mass, nutrient content, and hull thickness characteristics affected the scatter-hoarding decision processes.
EN
In this paper, the shape of the spinneret capillary was discussed, and optimized spinneret capillaries were successfully processed by a computer numerical control processing method which takes a C-shape silver electrode as the basic unit. Based on the optimised spinning process, a new type of square 8-hole hollow PET fibre was prepared by the experimental method.
PL
W artykule omówiono i zoptymalizowano kształt kapilary przędzalniczej, przy użyciu komputerowej metody sterowania numerycznego i zastosowaniem srebrnej elektrody w kształcie litery C. W oparciu o zoptymalizowany proces przędzenia opracowano nowy rodzaj kwadratowych 8-otworowych włókien poliestrowych z pustymi przestrzeniami.
EN
Super high speed permanent magnet generators (SHSPMG) usually operate at high frequency. The external characteristic of the SHSPMG under condition of high frequency operation is quite different from that of conventional generators. Therefore, it is necessary to study the external characteristic of the SHSPMG. Based on the finite element method, this paper studied the factors that affect the external characteristic of the SHSPMG. Combining the vector method and the finite element method, the external characteristic of the SHSPMG with the inductive load and the resistance load was studied. The variation law of the generator terminal voltage with the change of the load and current was obtained, and the key factors affecting the external characteristic of the SHSPMG were determined. The influences of the armature resistance, power factor, frequency and permanent magnet performance on the external characteristic of the SHSPMG were studied. The influence mechanism of different parameters on the generator external characteristic was revealed. The influence degree of each factor on the voltage regulation was determined. The conclusions can provide reference for the design and research of the SHSPMG.
EN
Biomimetic mineralized composite scaffolds are widely used as natural bone substitute materials in tissue engineering by inducing and assembling bonelike apatite. In this study, the single lamellar structure of graphene oxide (GO) powder was prepared via an improved Hummers’ method. Methods: To better mimic natural bone, the collagen (COL)/Nano-hydroxyapatite (nHA)/graphene oxide (GO) composite material was prepared by simulated body fluid (SBF) method using COL/GO as a matrix template. Hydroxyapatite (HA) with calcium ion deficiency was achieved via biomimetic mineralization, and it had properties closer to those of natural bone than pure HA has. Results: The mineralized COL/nHA/GO composites exhibited loose porous structures, and the connectivity of the holes was good and thus beneficial to the exchange of nutrients and excreted metabolites. Conculsions: Antibacterial and MTT experiment confirmed that the COL/nHA/GO composite material had excellent antibacterial property and biocompatibility. Hence, these results strongly suggested the mineralized COL/nHA/GO composite is a good candidate biomaterial to be applied in bone tissue engineering.
EN
Large errors of low-cost MEMS inertial measurement unit (MIMU) lead to huge navigation errors, even wrong navigation information. An integrated navigation system for unmanned vessel is proposed. It consists of a low-cost MIMU and Doppler velocity sonar (DVS). This paper presents an integrated navigation method, to improve the performance of navigation system. The integrated navigation system is tested using simulation and semi-physical simulation experiments, whose results show that attitude, velocity and position accuracy has improved awfully, giving exactly accurate navigation results. By means of the combination of low-cost MIMU and DVS, the proposed system is able to overcome fast drift problems of the low cost IMU.
EN
A compressive optical image encryption method, which combines compressive sensing with phase-shifting interferometry on a joint transform correlator, is proposed in the fully optical domain. The object image is first permutated using a binary scrambling method. Next, the permutated object field is encrypted and registered as the holograms by phase-shifting interferometry on the joint transform correlator setup. Then, the encrypted images and the key are compressed to the compressed data using single-pixel compressive imaging. The original image can be reconstructed and decrypted using the specified algorithm. The simulations demonstrate that the method is effective and suitable for image security transmission.
EN
A new covering technology for producing covered yarns is proposed in this article. On a traditional yarn covering machine, a hollow spindle rotates with a bobbin of the outer wrapping yarn. In the new equipment, the turntable rotates with only one single outer wrapping yarn. With a magnetic device, the bobbin of core yarns is suspended in a balloon formed by outer wrapping yarns. The rotation speed of the turntable can reach 40000 rpm. A series of experiments on the new equipment were conducted and some covered yarn samples were obtained. The performance of these samples were tested and compared with that produced by traditional machines.
PL
W artykule zaproponowano nową technologię przędzenia z owijaniem. W eksperymentach zastosowano 5 prędkości obrotowych: 12.000, 20.000, 27.000, 32.000 and 35.000 r.p.m. Przy użyciu mikroskopu porównano otrzymane przędze z przędzami otrzymanymi metodą tradycyjną. Stwierdzono, że tradycyjna przędza była bardziej puszysta, a przędza otrzymana nową metodą charakteryzowała się dobrą równomiernością. Po porównaniu dwóch rodzajów przędz stwierdzono, że równomierność skrętu przędzy uzyskanej nową metodą jest wyższa, ponieważ w nowym sposobie przędzenia zastosowano synchroniczny napęd taśmy, co skutkuje mniejszymi wahaniami prędkości obrotowej.
EN
In the process of producing covered yarn, a single outer wrapping yarn forms a balloon when it rotates at high speed. In this work, we used a mathematical model of a balloon formed by polyamide, which is a common outer wrapping yarn, and verified its feasibility with a group of experimental data. The effects of yarn tension, rotation speed, balloon height and turntable radius on the balloon shape were analysed and the correctness simultaneously demonstrated.
PL
W procesie przędzenia z owijaniem, przędza owijająca obracając się z dużą prędkością tworzy balon. W pracy wykorzystano model matematyczny balonu utworzonego z poliamidowej przędzy owijającej i zweryfikowano jego wykonalność z grupą danych eksperymentalnych. Analizowano wpływ naprężeń przędzy, prędkości obrotowej, wysokości balonu i promienia stołu obrotowego na kształt balonu. Przedstawione wyniki mogą być podstawą do wyboru odpowiednich parametrów i uzyskania optymalnego kształtu balonu.
EN
Retinal images play an important role in the early diagnosis of diseases such as diabetes. In the present study, an automatic image processing technique is proposed to segment retinal blood vessels in fundus images. The technique includes the design of a bank of 180 Gabor filters with varying scale and elongation parameters. Furthermore, an optimization method, namely, the imperialism competitive algorithm (ICA), is adopted for automatic parameter selection of the Gabor filter. In addition, a systematic method is proposed to determine the threshold value for reliable performance. Finally, the performance of the proposed approach is analyzed and compared with that of other approaches on the basis of the publicly available DRIVE database. The proposed method achieves an area under the receiver operating characteristic curve of 0.953 and an average accuracy of up to 0.9392. Thus, the results show that the proposed method is well comparable with alternative methods in the literature.
EN
At present, the drivers with different control methods are used in most of permanent magnet synchronous motors (PMSM). A current outputted by a driver contains a large number of harmonics that will cause the PMSM torque ripple, winding heating and rotor temperature rise too large and so on. In this paper, in order to determine the influence of the current harmonics on the motor performance, different harmonic currents were injected into the motor armature. Firstly, in order to study the influence of the current harmonic on the motor magnetic field, a novel decoupling method of the motor magnetic field was proposed. On this basis, the difference of harmonic content in an air gap magnetic field was studied, and the influence of a harmonic current on the air gap flux density was obtained. Secondly, by comparing the fluctuation of the motor torque in the fundamental and different harmonic currents, the influence of harmonic on a motor torque ripple was determined. Then, the influence of different current harmonics on the eddy current loss of the motor was compared and analyzed, and the influence of the drive harmonic on the eddy current loss was obtained. Finally, by using a finite element method (FEM), the motor temperature distribution with different harmonics was obtained.
EN
With the wide use of AIS system in the world, especially in ports and the waters with heavy traffic, AIS message loss may be related to environmental conditions, obstacle, limitation of VHF technology and AIS network overload, thereby reducing the AIS signal successful reception rate. This paper selected typical AIS data received by Yagi and Omni antennas at the same time in specific waters, uses grid and AIS data recovery technology, establishes the AIS signal coverage model, analyzes signal reception rate of Yagi antenna and Omni antenna of AIS base station, and verified the superiority of Yagi antenna in AIS signal reception rate.
13
Content available An Algorithm for Interpolating Ship Motion Vectors
EN
Interpolation of ship motion vectors is able to be used for estimating the lost ship AIS dynamic information, which is important for replaying marine accidents and for analysing marine traffic data. The previous methods can only interpolate ship’s position, while not including ship's course and speed. In this paper, vector function is used to express the relationship between the ship’s time and space coordinates, and the tangent of the vector function and its change rate are able to express physical characteristics of ship’s course, speed and acceleration. The given AIS dynamic information can be applied to calculate the parameters of ship's vector function and then the interpolation model for ship motion vectors is developed to estimate the lost ship dynamic information at any given moment. Experiment results show that the ship motion vector function is able to depict the characteristics of ship motions accurately and the model can estimate not only the ship’s position but also ship’s course and speed at any given moment with limited differences.
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.
15
Content available remote 2-/3-D Digital Material Representation and Evaluation of Metal Foams
EN
Recently metal foams are becoming popular in engineering application due to their high energy absorption ability and low density, which are being utilised in automotive engineering and aerospace engineering as well as biomedical engineering. As a typical porous or cellular material, from the material design’s point of view, metal foams have typical heterogeneous structures cross length scales, which can be defined by only two phases: matrix material and voids, which is termed as cells or pores . Their structures can be characterised by several main geometric parameters related to the cells, such as size, shape, spatial distribution and arrangement and so on. The digital material representation of metal foams has been employed to represent metal foams accounting for their complex structures. However random distributions of the size and shape of cells in most foam materials make the digital material representation and modelling of such materials very complicated. Furthermore, effects of size and shape of cells on mechanical behaviours of metal foams have been found and investigated numerically and experimentally in authors' previous studies in which the authors have developed a digital framework for the representation, modelling and evaluation of multi-phase materials including metal foams. In this study, the developed digital framework for the representation, modelling and evaluation of microstructured or multi-phase materials has been further developed with a multi-scale sense including both two-/three-dimensional (2-/3-D) finite element modelling to represent metal foams with a certain distribution on cell size and shape, which can be used for digital or virtual testing to determine mechanical properties and behaviours of such foams. A linkage between 2-D and 3-D finite element models has been build up through a comparativeness analysis between them. For validation and verification purpose, the results obtained from these models have been compared with those from experimental work and good agreement has been found which demonstrated the effectiveness of the digital framework developed for metal foams.
PL
Ze względu na ich dużą zdolność do absorpcji energii i niską gęstość pianki metaliczne znajdują ostatnio szerokie zastosowanie w przemysłach samochodowym i lotniczym, a także w bioinżynierii. Jako typowy materiał porowaty lub komórkowy pianki metaliczne mają strukturę niejednorodną, która może być zdefiniowana przez dwie fazy: materiał osnowy i pustki nazywane komórkami lub porami. Struktury komórek są charakteryzowane przez ich główne parametry geometryczne, takie jak rozmiar, kształt, rozkład w przestrzeni i aranżacja. Cyfrowa reprezentacja materiału została wykorzystana do reprezentowania pianek metalicznych z uwzględnieniem ich złożonej struktury. Z drugiej strony nierównomierność rozkładu rozmiaru i kształtu komórek w większości pianek powoduje, że taka cyfrowa reprezentacja i modelowanie stają się bardzo trudne. Wpływ rozmiaru i kształtu komórek na własności mechaniczne pianek metalicznych był badany numerycznie i doświadczalnie we wcześniejszych pracach autorów. W tych pracach opracowana została numeryczna platforma dla reprezentacji, modelowania i oceny wielofazowych materiałów, w tym pianek metalicznych. W niniejszej pracy przedstawiono dalszy rozwój tej platformy. Stworzono wieloskalowe modele 2D i 3D połączone z metodą elementów skończonych (MES) do opisu pianek metalicznych z zadanym rozkładem rozmiaru i kształtu komórek. Ten program może być dalej stosowany do wyznaczania własności mechanicznych oraz do opisu zachowania się pianek metalicznych pod obciążeniem. Połączenie między modelami 2D i 3D MES zostało zbudowane na podstawie analizy podobieństwa między tymi rozwiązaniami. Dla walidacji i weryfikacji modelu porównano otrzymane wyniki z badaniami doświadczalnymi i otrzymano dobrą zgodność, co potwierdziło efektywność cyfrowej platformy dla pianek metalicznych.
EN
As there are more and more Automatic Identification System (AIS) sets have been deployed onboard, it is getting easier for people to trace vessels. Today, many online vessel monitoring services have been developed; however, most of them are based on AIS information. Because the coverage limitation of VHF frequency, which the AIS set works on, is normally no more than 25 nautical miles, so these systems can not track vessels when they are beyond the coverage of the shore-based AIS station. In order to track ves-sels in all sea areas, we developed a comprehensive vessel tracking system, namely ManyShips, which inte-grates AIS, Inmarsat and China Beidou navigation satellite system. The running result of the system shows that the Beidou satellite system can track vessels within Asian-Pacific region while the Inmarsat-C station polling service can help people tracking vessels within sea area A3.
17
Content available remote Analysis Research of Control Method Model on Automobile Brake Test Rig
EN
This paper, firstly in accordance with the engineering design method, PID controller are used to control the current loop and speed loop common on double closed-loop DC converter, and build dual-loop PID control model, and Matlab’s emulation to model, as well as analysis and evaluate the structural of the simulation. Because conventional PID control can not meet the parameters of the controlled object changes and lack of non-linear characteristics, the fuzzy self-tuning PID can overcome the uncertainty and nonlinear objects, furthermore the fuzzy self-tuning PID has more flexibility and adaptability, so this paper putting to use fuzzy self-tuning PID controller for dual-speed loop in the closed-loop system to transform, so that it has not or less affected by the object model, you can achieve high performance, robustness and other advantages.
PL
W artykule opisano metodę testowania system hamulcowego w pojazdach samochodowych. Ay uniezależnić wyniki testu od parametrów układu sterowania zaproponowano ulepszony kontroler PID z automatycznym strojeniem i wykorzystaniem logiki rozmytej.
EN
Novel pH-sensitive hydrogels were prepared through crosslinking of poly(.gamma.-glutamic) acid (.gamma.-PGA) by using 1,4-butanediol diglycidyl ether as a cross-linker, tetraethylammonium bromide as a catalyst, and reacting in DMSO. The dependence of the swelling ratio of the hydrogels on pH values, ionic strength and cross-linking degree was investigated. It was found that the pH-sensitive range was clearly extended through introducing multiple hydrogen bonds to the hydrogel network during the preparation. The swelling ratios of ?-PGA hydrogels increased with the increase in pH of the aqueous solution from 2 to 9. The swelling of the .gamma.-PGA hydrogels was firstly controlled by the ionization of carboxyl groups in the hydrogels within the pH range from 2 to 5, and then controlled by breaking of the multiple hydrogen bonds in the hydrogels within the pH range from 5 to 9. The swelling ratios of .gamma.-PGA hydrogels were also strongly dependent on the ionic strength of the medium and cross-linking degree of the hydrogels. Increasing the ionic strength and the crosslinking degree resulted in a decrease in the swelling ratio of the hydrogels.
19
Content available remote Strain distribution analysis based on the digital material representation
EN
Results of research on application of modern numerical approaches for analysis of influence of microstructure heterogeneities on strain distribution during material processing are presented in this work. This work is part of the research towards development of the tool for detailed microstructure modeling. The main focus here is put on the micro scale behavior, where advantages of digital material representation can be taken into account. Digital representation allows to model microstructure with its features like crystallographic orientation, grain boundaries or phase boundaries taken in an explicit manner. By combination of these digital structures with numerical simulation methods a possibility to improve quality of results was created. Developed method can be used to design specifically dedicated microstructures, which meet very strict requirements. In the first part of the work the review of various ideas of digital representation of materials is presented. It is followed by a short description of the application of the developed approach to creation of the digital microstructures. The main focus is put on the application of cellular automata technique. Afterwards, obtained digital microstructures of ferrite steel and two phase steels are used as an input data for the finite element analysis of the compression test. Selected results are also presented and discussed in the paper.
PL
W pracy przedstawiono postęp w badaniach nad zastosowaniem nowoczesnych metod numerycznych do analizy wpływu niejednorodności mikrostruktury na stan odkształcenia w materiałach poddanych obciążeniom. Przeprowadzone badania dotyczą przede wszystkim skali mikro, ponieważ szczególny nacisk w modelowaniu położono na wykorzystanie zalet cyfrowej reprezentacji materiału. Cyfrowa reprezentacja pozwala wiernie odwzorować rzeczywistą mikrostrukturę materiałów polikrystalicznych z jej cechami charakterystycznymi (np. orientacja krystalograficzna, granice ziaren, granice faz) w formie jawnej. Wykorzystanie takiej reprezentacji w połączeniu z metodami symulacji numerycznych stwarza możliwość uzyskania nowej jakości wyników, które mogą zostac użyte do projektowania dedykowanych mikrostruktur materiałowych zapewniajacych zadane własności. W artykule przedstawiono zarówno przegląd dotychczasowych zastosowań koncepcji cyfrowej reprezentacji materiału jak również propozycje własnych rozwiązań, takich jak np.: automaty komórkowe stosowane do modelowania zjawisk zachodzących w mikrostrukturze. Wygenerowane w ten sposób mikrostruktury dla stali ferrytycznej oraz stali dwufazowych poddano następnie symulacjom spęczania z wykorzystaniem komercyjnych pakietów metody elementów skończonych. Dyskusja otrzymanych wyniki również jest zawarta w niniejszej pracy.
EN
Automatic vessel collision-avoidance systems have been studied in the fields of artificial intelligence and navigation for decades. And to facilitate automatic collision-avoidance decision-making in two-vessel-encounter situation, several expert and fuzzy expert systems have been developed. However, none of them can negotiate with each other as seafarers usually do when they intend to make a harmonious and more economic overall plan of collision avoidance in the COLREGS-COST-HIGH situations where collision avoidance following the International Regulations for Preventing Collisions at Sea(COLREGS) costs too much. A negotiation framework was put forward in our previous research to enable vessels to negotiate for optimizing collision avoidance in the COLREGS-COST-HIGH situations at open sea. In this paper, the negotiation framework is improved by considering the planned route of both vessels. The simulation results show that more economic overall plan of collision avoidance may be achieved by the improved framework when one or both parties deviate from their planed route or are approaching their next way points.
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