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排序方式: 共有983条查询结果,搜索用时 15 毫秒
71.
We developed a pipelined scheduling technique of functional hardware and software modules for platform‐based system‐on‐a‐chip (SoC) designs. It is based on a modified list scheduling algorithm. We used the pipelined scheduling technique for a performance analysis of an MPEG4 video encoder application. Then, we applied it for architecture exploration to achieve a better performance. In our experiments, the modified SoC platform with 6 pipelines for the 32‐bit dual layer architecture shows a 118% improvement in performance compared to the given basic SoC platform with 4 pipelines for the 16‐bit single‐layer architecture. 相似文献
72.
M. R. Geller D. J. Thouless S. W. Rhee W. F. Vinen 《Journal of Low Temperature Physics》2000,121(5-6):411-416
It has been known since the pioneering work of Onsager and Feynman that the statistical mechanics and dynamics of vortices play an essential role in the behavior of superfluids and superconductors. However, the theory of vortices in quantum fluids remains in a most unsatisfactory state, with many conflicting results in the literature. In this paper we review the theory of Thouless, Ao and Niu, which gives an expression for the total transverse force acting on a quantized vortex that is in apparent disagreement with the word of lordanskii and of Lifshitz and Pitaevskii. In particular, no transverse force proportional to the asymptotic normal fluid velocity was found. We use two-fluid hydrodynamics to study this discrepancy. 相似文献
73.
Effects of cooking methods on starch hydrolysis kinetics and digestion-resistant fractions of rice and soybean 总被引:1,自引:0,他引:1
In this study, we investigated the effects of cooking methods and digestion-resistant fractions on the starch hydrolysis kinetics
of rice and soybeans. The RS1 contents in unheated rice and soybeans were found to be high at 5.3 and 4.9%, respectively.
After heating, the RS1 levels of the rice and soybeans were significantly reduced to 0.4 and 2.4%, respectively. The total
nonstarch polysaccharide (NSP) content was not significantly different according to heat treatment, but the heat treatments
affected the amounts of water insoluble nonstarch polysaccharides (WISNSP) and water soluble nonstarch polysaccharides (WSNSP).
The level of WISNSP in the unheated samples was higher than the WSNSP of both samples; however, the WISNSP level showed a
reducing trend after heating. Also, total pentosan and water soluble pentosan contents showed similar trends with total NSP
and WSNSP. The hydrolysis indices (HI) of the unheated rice and soybeans were low (36.2 and 40.3%), while the heated group
had high levels (89.5 and 45.0%). Among the cooking methods, the highest kinetic constants (0.284 and 0.199) were found with
autoclaving for both rice and soybeans, followed by electric cooker (0.282 and 0.170), microwave oven (0.256 and 0.155), and
stone pot (0.238 and 0.167). Particularly, all soybean samples appeared to have lower starch hydrolysis kinetics than the
rice samples. The RS contents of the rice and soybeans were highest in the samples that were cooked in the stone pot, at 1.2
and 3.8%, respectively. 相似文献
74.
This article presented the results of an electromagnetic field analysis inside a rectangular and triangular reverberation chamber being attached to the Schroeder Quadratic Residue Diffusers (QRD). Simulation results showed that a triangular chamber, which had more mode distribution than the rectangular chamber in the defined volume, had advantages of producing improved field uniformity. © 2002 Wiley Periodicals, Inc. Int J RF and Microwave CAE 12: 198–205, 2002. 相似文献
75.
K. Park Y. Kim J. Byeon K. Sung C. Yeom S. Rhee 《Journal of Mechanical Science and Technology》2007,21(10):1720-1725
A control rod device (CRD) nozzle attaches to the hemispherical surface of a reactor head with J-groove welding. Primary water
stress corrosion cracking (PWSCC) causes degradation in these welds, which requires that these defect areas be repaired. To
perform this repair welding automatically on a complicated weld groove shape, an auto-welding system was developed incorporating
a laser vision sensor that measures the 3-dimensional (3D) shape of the groove and a weld-path creation program that calculates
the weld-path parameters. Welding trials with a J-groove workpiece were performed to establish a basis for developing this
auto-welding system. Because the reactor head is placed on a lay down support, the outer-most region of the CRD nozzle has
restricted access. Due to this tight space, several parameters of the design, such as size, weight and movement of the auto-welding
system, had to be carefully considered. The cross section of the J-groove weld is basically an oval shape where the included
angle of the J-groove ranges from 0 to 57 degrees. To measure the complex shape, we used double lasers coupled to a single
charge coupled device (CCD) camera. We then developed a program to generate the weld-path parameters using the measured 3D
shape as a basis. The program has the ability to determine the first and final welding positions and to calculate all weld-path
parameters. An optimized image-processing algorithm was applied to resolve noise interference and diffused reflection of the
joint surfaces. The auto-welding system is composed of a 4-axis manipulator, gas tungsten arc welding (GTAW) power supply,
an optimized designed and manufactured GTAW torch and a 3D laser vision sensor. Through welding trials with 0 and 38-degree
included-angle workpieces with both J-groove and U-groove weld, the performance of this auto-welding system was qualified
for field application. 相似文献
76.
Byung Sup Rho Saekyoung Kang Han Seo Cho Hyo-Hoon Park Sang-Won Ha Byoung-Ho Rhee 《Lightwave Technology, Journal of》2004,22(9):2128-2134
In this paper, a new architecture for a chip-to-chip optical interconnection system is demonstrated that can be applied in a waveguide-embedded optical printed circuit board (PCB). The experiment used 45/spl deg/-ended optical connection rods as a medium to guide light paths perpendicularly between vertical-cavity surface-emitting lasers (VCSELs), or photodiodes (PDs) and a waveguide. A polymer film of multimode waveguides with cores of 100/spl times/65 /spl mu/m was sandwiched between conventional PCBs. Via holes were made with a diameter of about 140 /spl mu/m by CO/sub 2/-laser drilling through the PCB and the waveguide. Optical connection rods were made of a multimode silica fiber ribbon segment with a core diameter of 62.5 and 100 /spl mu/m. One end of the fiber segment was cut 45/spl deg/ and the other end 90/spl deg/ by a mechanical polishing method. These fiber rods were inserted into the via holes formed in the PCB, adjusting the insertion depth to locate the 45/spl deg/ end of rods near the waveguide cores. From this interconnection system, a total coupling efficiency of about -8 dB was achieved between VCSELs and PDs through connection rods and a 2.5 Gb/s /spl times/ 12-ch data link demonstrated through waveguides with a channel pitch of 250 /spl mu/m in the optical PCB. 相似文献
77.
Rhee T Lewis JP Neumann U Nayak KS 《IEEE transactions on visualization and computer graphics》2011,17(3):368-379
This paper describes a complete system to create anatomically accurate example-based volume deformation and animation of articulated body regions, starting from multiple in vivo volume scans of a specific individual. In order to solve the correspondence problem across volume scans, a template volume is registered to each sample. The wide range of pose variations is first approximated by volume blend deformation (VBD), providing proper initialization of the articulated subject in different poses. A novel registration method is presented to efficiently reduce the computation cost while avoiding strong local minima inherent in complex articulated body volume registration. The algorithm highly constrains the degrees of freedom and search space involved in the nonlinear optimization, using hierarchical volume structures and locally constrained deformation based on the biharmonic clamped spline. Our registration step establishes a correspondence across scans, allowing a data-driven deformation approach in the volume domain. The results provide an occlusion-free person-specific 3D human body model, asymptotically accurate inner tissue deformations, and realistic volume animation of articulated movements driven by standard joint control estimated from the actual skeleton. Our approach also addresses the practical issues arising in using scans from living subjects. The robustness of our algorithms is tested by their applications on the hand, probably the most complex articulated region in the body, and the knee, a frequent subject area for medical imaging due to injuries. 相似文献
78.
This paper proposes an efficient multiuser adaptive modulation and coding (AMC) scheme that considers inevitable feedback delay by employing short-term and long-term channel state information (CSI) in time-varying frequency-selective fading channels. By taking the statistic of the true signal-to-noise ratio (SNR) at a given predicted SNR value into account, the required transmit power to meet the target packet-error-rate (PER) can be obtained and used for user selection, power allocation, and modulation and coding set (MCS) selection. In addition, a simple and useful approximation method of obtaining the required transmit power is proposed. The performance of the proposed scheme is shown to be much better than that of conventional schemes without considering the feedback delay or the prediction error. The proposed scheme can also reduce the feedback resource while maintaining the system throughput by allocating different feedback resources to different users according to their prediction error variances. 相似文献
79.
K.Y. Rhee 《Composite Structures》1993,26(3-4):109-113
The single specimen technique is effectively used in classical fracture mechanics for evaluating the J-integral from a single test record. It was previously shown using a cracked lap shear specimen that the technique can be applied to composite structures and the energy release rate of composite laminates can be determined from a single test specimen. The objective of this investigation is to determine the ηel form of a double cantilever beam (DCB) specimen, and to compare it with that of a compact tension (CT) specimen. The result showed that while ηel is linearly related to crack length for the CT specimen, it is proportional to the reciprocal of the crack length for the DCB composite specimen. Also, GIc determined from the compliance method was compared with that determined from the ηel approach. The result showed that the ηel form determined from a single beam analysis can be used to determine GIc from a single test record. 相似文献
80.
A 2.5-GHz/900-MHz dual fractional-N/integer-N frequency synthesizer is implemented in 0.35-μm 25-GHz BiCMOS. A ΔΣ fractional-N synthesizer is employed for RF channels to have agile switching, low in-band noise, and fine frequency resolution. Implementing two synthesizers with an on-chip ΔΣ modulator in a small package is challenging since the modulator induces substantial digital noise. In this work, several design aspects regarding noise coupling are considered. The fractional-N synthesizer offers less than 10-Hz frequency resolution having the in-band noise contribution of -88 dBc/Hz for 2.47-GHz output frequency and -98 dBc/Hz for 1.15-GHz output frequency, both measured at 20-kHz offset frequency. The prototype dual synthesizer consumes 18 mW with 2.6-V supply 相似文献