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排序方式: 共有1297条查询结果,搜索用时 15 毫秒
1.
Yoshihiro Yajima 《时间序列分析杂志》1985,6(3):187-201
Abstract. We shall investigate the asymptotic behaviour of the sample autocorrelations and partial autocorrelations of a multiplicative ARIMA process and derive their limiting distributions. Some simulations are presented to illustrate the results obtained. 相似文献
2.
Takeshi Shiofuku Norihiro Abe Yoshihiro Tabuchi Hirokazu Taki Shoujie He 《Artificial Life and Robotics》2008,13(1):290-293
This paper presents an approach of measuring in real-time the vector of finger that is pointing to an object. DSP is used
in the operation processing unit in order to do the real-time processing. The steps include the extraction of flesh-colored
regions from an image, the labeling of the flesh-colored regions, and the detection of two characteristic positions on the
finger so that the direction that the finger is pointing at will be calculated. The entire process takes about 29 msec, which
makes it possible to have the frame rate of 34 fps. With this frame rate, this measurement approach is considered real-time
and promising to be merged into other application systems.
This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January
31–February 2, 2008 相似文献
3.
An effective system control method is presented for applying a three‐phase current‐source PWM converter with a deadbeat controller to active power filters (APFs). In the shunt‐type configuration, the APF is controlled such that the current drawn by the APF from the utility is equal to the current harmonics and reactive current required for the load. To attain the time‐optimal response of the APF supply current, a two‐dimensional deadbeat control scheme is applied to APF current control. Furthermore, in order to cancel both the delay in the two‐dimensional deadbeat control scheme and the delay in DSP control strategy, an Adaptive Line Enhancer (ALE) is introduced in order to predict the desired value three sampling periods ahead. ALE has another function of bringing robustness to the deadbeat control system. Due to the ALE, settling time is made short in a transient state. On the other hand, total harmonic distortion (THD) of source currents can be minimized compared to the case where ideal identification of the controlled system can be made. The experimental results obtained from the DSP‐based APF are also reported. The compensating ability of this APF is very high in accuracy and responsiveness although the modulation frequency is rather low. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(1): 50–61, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20014 相似文献
4.
Rod-shaped BaTiO3 powder particles have been prepared from rod-shaped TiO2 ·nH2O and BaCO3 in molten chloride. The morphology of BaTiO3 particles was studied referring to the effects of the chemical species of the starting titanium compound, amount of chloride, particle size of the titanium compound and reaction conditions, and the preparation condition of rod-shaped BaTiO3 has been determined: i.e., large TiO2 ·nH2O particles were heated at 700°C in molten salt with an equal amount of BaTiO3. This condition was effective in suppressing the formation of BaTiO3 by a solution-precipitation process as well as the deformation of either TiO2 ·nH2O or BaTiO3, which are responsible for the formation of equiaxed BaTiO3 particles. The obtained rod-shaped BaTiO3 particles had a cubic symmetry. Electron diffraction analysis showed that the following topotactic relation is retained; 0 1 0potassium tetratitanate 0 1 0hydrated titania 1 0 0anatase 1 0 0barium titanate 相似文献
5.
Effect of compressive and tensile strains on the electrical resistivity of carbon microcoil/silicone-rubber composites 总被引:1,自引:0,他引:1
Spring-shaped carbon microcoils (CMCs) were embedded in silicone-rubber to form CMC/silicone-rubber composites. The electrical and mechanical properties of the composites were examined and compared with those of the composites involving straight carbon nanofibers and carbon blacks as a conductor. The electrical resistivity of the CMC/silicone-rubber composites decreased dramatically by increasing the CMC content and was as low as 100 Ω cm at 10% CMC volume content. With a compressive or tensile strain, the resistivity increased sharply much more than that of the other composites. The high resistive sensitivity of the composites is ascribed to an easy-to-deform configuration of the CMCs in the composites under an applied stress. 相似文献
6.
This paper deals with the frame topology optimization under the frequency constraint and proposes an algorithm that solves a sequence of relaxation problems to obtain a local optimal solution with high quality. It is known that an optimal solution of this problem often has multiple eigenvalues and the feasible set is disconnected. Due to these two difficulties, conventional nonlinear programming approaches often converge to a local optimal solution that is unacceptable from a practical point of view. In this paper, we formulate the frequency constraint as a positive semidefinite constraint of a certain symmetric matrix, and then relax this constraint to make the feasible set connected. The proposed algorithm solves a sequence of the relaxation problems with gradually decreasing the relaxation parameter. The positive semidefinite constraint is treated with the logarithmic barrier function and, hence, the algorithm finds no difficulty in multiple eigenvalues of a solution. Numerical experiments show that global optimal solutions, or at least local optimal solutions with high qualities, can be obtained with the proposed algorithm. 相似文献
7.
Taiju Takahashi Yukihiro Kudoh Yuichi Saito Yoshihiro Aoyagi 《Journal of the Society for Information Display》2023,31(3):101-111
Recently, there has been considerable research on optical devices, such as liquid crystal (LC) lenses and special optical plates, using LCs. In such devices, relatively small LC cells are frequently used, or unique LC orientations are required. As an LC orientation process, we focused on the LC director's orientation induced by the magnetic force line distribution of a small neodymium magnet. We propose a simple method for obtaining radial orientation, which is rather difficult to obtain using the ordinary rubbing method. The initial orientation in the LC cell is a vertical orientation cell with almost zero azimuth anchoring. With the proposed method, the reorientation process is performed with an assisting electric field and a small permanent magnet, unlike the conventional magnetic field orientation process that requires a large electromagnet. Furthermore, a polymer stabilization treatment is used to fix the obtained radial orientation pattern in the LC cell. After the treatment, the applying voltage can control the tilt angle of the director in weak polymer treatment, and a completely fixed orientation pattern can be obtained that in strong. 相似文献
8.
The purpose of this study was to design an endoscopic dissector handle and objectively assess its usability. The handles were designed with increased contact area between the fingers and thumb and the eye rings, and the eye rings were modified to have a more perpendicular insertion angle to the finger midline. Four different handle models were compared, including a conventional product. Subjects performed dissection, exclusion, grasping, precision manipulation and precision handling tasks. Electromyography and subjective evaluations were measured. Compared to conventional handles, the designated handle reduced the muscle load in the extensor and flexor muscles of the forearm and increased subjective stability. The activity of the first dorsal interosseous muscle was sometimes influenced by the shape of the other parts. The ergonomically designed endoscopic dissector handle used in this study achieved high usability. Medical instrument designs based on ergonomic concepts should be assessed with objective indices.
Practitioner Summary: The endoscopic dissector handles were designed with increased contact area and more suitable insertion angle between the fingers and thumb and the eye rings. Compared to conventional handles, the designated handle reduced the muscle load in the extensor and flexor muscles of the forearm and increased subjective stability. 相似文献
9.
Isao Kobayashi Yoshihiro Wada Kunihiko Uemura Mitsutoshi Nakajima 《Microfluidics and nanofluidics》2008,5(5):677-687
This study investigated the generation of oil drops using new symmetric and asymmetric through-hole-array devices made of
stainless steel. The through-hole-array devices were built by piling up six stainless-steel plates, each having circular micro-holes
with a diameter of 300 or 500 μm or micro-slots with a shorter line of 300 or 500 μm. Drops were generated by injecting a
dispersed phase (refined soybean oil) via the through-hole array into a compartment filled with a continuous phase (Milli-Q
water solution containing one of two emulsifiers). The drop detachment from symmetric and asymmetric through holes was observed
in real time and analyzed. Uniform oil drops with average diameters of 1.0–4.1 mm and coefficients of variation of typically
less than 6% were generated using symmetric and asymmetric through-hole-array devices. The resultant drop diameters for asymmetric
through-hole arrays were significantly smaller than those for symmetric through-hole arrays. This paper also discusses experimental
results regarding the effects of the microstructure, the dimensions of the through holes, and the type of emulsifier on drop
generation and the resultant drop diameter. 相似文献
10.
Straight-through microchannel devices for generating monodisperse emulsion droplets several microns in size 总被引:1,自引:1,他引:0
Isao Kobayashi Takayuki Takano Ryutaro Maeda Yoshihiro Wada Kunihiko Uemura Mitsutoshi Nakajima 《Microfluidics and nanofluidics》2008,4(3):167-177
The authors recently proposed a promising technique for producing monodisperse emulsions using a straight-through microchannel
(MC) device composed of an array of microfabricated oblong holes. This research developed new straight-through MC devices
with tens of thousands of oblong channels of several microns in size on a silicon-on-insulator plate, and investigated the
emulsification characteristics using the microfabricated straight-through MC devices. Monodisperse oil-in-water (O/W) and
W/O emulsions with average droplet diameters of 4.4–9.8 μm and coefficients of variation of less than 6% were stably produced
using surface-treated straight-through MC devices that included uniformly sized oblong channels with equivalent diameters
of 1.7–5.4 μm. The droplet size of the resultant emulsions depended greatly on the size of the preceding oblong channels.
The emulsification process using the straight-through MC devices developed in this research had very high apparent energy
efficiencies of 47–60%, defined as (actual energy input applied to droplet generation/theoretical minimum energy input necessary
for making droplets) × 100. Straight-through MC devices with numerous oblong microfluidic channels also have great potential
for increasing the productivity of monodisperse fine emulsions. 相似文献