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101.
102.
Efficient parallel processing of competitive learning algorithms 总被引:1,自引:0,他引:1
Kentaro Sano Shintaro Momose Hiroyuki Takizawa Hiroaki Kobayashi Tadao Nakamura 《Parallel Computing》2004,30(12):1361-1383
Vector quantization (VQ) is an attractive technique for lossy data compression, which has been a key technology for data storage and/or transfer. So far, various competitive learning (CL) algorithms have been proposed to design optimal codebooks presenting quantization with minimized errors. Although algorithmic improvements of these CL algorithms have achieved faster codebook design than conventional ones, limitations of speedup still exist when large data sets are processed on a single processor. Considering a variety of CL algorithms, parallel processing on flexible computing environment, like general-purpose parallel computers is in demand for a large-scale codebook design. This paper presents a formulation for efficiently parallelizing CL algorithms, suitable for distributed-memory parallel computers with a message-passing mechanism. Based on this formulation, we parallelize three CL algorithms: the Kohonen learning algorithm, the MMPDCL algorithm and the LOJ algorithm. Experimental results indicate a high scalability of the parallel algorithms on three different types of commercially available parallel computers: IBM SP2, NEC AzusA and PC cluster. 相似文献
103.
The joinability of unalloyed titanium and the bond strength of similar titanium welded joints by ultrasonic welding were investigated. It turned out that sound welded joints of similar titanium were obtained by using the jig for fixing both base metals. In the case of non-fixing and fixing the lower base metal, sound welded joints were not usually obtained due to the slip between the two base metals. Producing welded joints having sufficient bond strength required a certain threshold value of the ultrasonic energy. When the ultrasonic welding was carried out under the condition where the ultrasonic energy was higher than a threshold value (approximately 2000 W s), the welded joints were fractured within the titanium base metal but not at the interface. The values of the bond strength were associated with the fixing method and the surface roughness of the base metals. The bond interface was joined metallurgically for the most part, although some small voids were observed on the bond interface by SEM and EPMA observation. 相似文献
104.
Murat Manguoglu Kenji Takizawa Ahmed H. Sameh Tayfun E. Tezduyar 《Computational Mechanics》2011,48(3):377-384
Iterative solution of large sparse nonsymmetric linear equation systems is one of the numerical challenges in arterial fluid–structure interaction computations. This is because the fluid mechanics parts of the fluid + structure block of the equation system that needs to be solved at every nonlinear iteration of each time step corresponds to incompressible flow, the computational domains include slender parts, and accurate wall shear stress calculations require boundary layer mesh refinement near the arterial walls. We propose a hybrid parallel sparse algorithm, domain-decomposing parallel solver (DDPS), to address this challenge. As the test case, we use a fluid mechanics equation system generated by starting with an arterial shape and flow field coming from an FSI computation and performing two time steps of fluid mechanics computation with a prescribed arterial shape change, also coming from the FSI computation. We show how the DDPS algorithm performs in solving the equation system and demonstrate the scalability of the algorithm. 相似文献
105.
T Takizawa K Arishima M Yamamoto M Shirai H Somiya Y Eguchi 《Canadian Metallurgical Quarterly》1993,55(3):379-381
This work was conducted to know whether thyroxine (T4) when injected into fetal rats would induce a constriction of the ductus arteriosus (DA). In Experiment 1, fetal rats on day 20 of gestation were given a subcutaneous injection of 1 or 10 micrograms T4 through the maternal uterine wall, and were autopsied 3 or 6 hr later. Similarly, in Experiment 2, the mother rats were given an injection of hydrocortisone (10 mg/kg) just after fetal T4 injections. In either series of experiments, uninjected littermates served as controls. According to the whole-body freezing and shaving method, the DA was exposed and calibrated under a dissecting microscope. In Experiment 1, the DAs of the T4-injected fetuses, 3 hr later, were significantly smaller in caliber than those of their controls, but recovered 6 hr later. In Experiment 2 with fetal T4 injection followed by maternal hydrocortisone injection, the DAs of the T4-injected fetuses were further smaller in caliber than those of their controls which were clearly shrunken as compared with those of controls in Experiment 1. These results indicate that T4 exerts a constrictive effect on the DA, an effect which is strengthened in the presence of hydrocortisone. 相似文献
106.
Toxoplasma gondii tissue cyst reactivation is a major pathogenic mechanism in ocular toxoplasmosis, disease associated with AIDS and organ transplantation. The mechanisms associated with cyst formation and reactivation have not been elucidated. The complexity of studying these issues in animal models has led to the development of in vitro tissue culture strategies for cyst formation. In the present study we have adopted the human embryonic lung fibroblast (HEL) as the host cell and have compared the cyst forming abilities of eight clinical isolates. We describe by transmission electron microscopy and quantitative light microscopy the development of cysts in vitro. The numbers of in vitro cysts increased with time for all isolates. Cyst cultures were stabilised by manipulation of the free parasite load, an observation not previously recorded. Thus, in this paper we describe a viable model for the analysis of the mechanisms of Toxoplasma cyst development. 相似文献
107.
Inductions of 3-L-nitrotyrosine in motor neurons after transient spinal cord ischemia in rabbits 总被引:1,自引:0,他引:1
M Sakurai N Fukuyama S Takizawa K Abe T Hayashi Y Shinohara H Nakazawa K Tabayashi 《Canadian Metallurgical Quarterly》1998,18(11):1233-1238
The induction and distribution of 3-L-nitrotyrosine (NO2-Tyr) were examined with HPLC and immunohistochemistry in rabbit spinal cords after 15 minutes of transient ischemia until 7 days of the reperfusion. After the 15-minute ischemia, there was a significant decrease of neurologic scores in the ischemic group compared with the sham-operated control group at 7 days of reperfusion (P = 0.0017), and the majority of motor neurons was selectively lost at 7 days of reperfusion (P = 0.0039). NO2-Tyr was transiently induced at 8 hours of reperfusion in the ventral part of the spinal cord (0.47%+/-0.86%, NO2-Tyr/total tyrosine; P = 0.0021), but was not induced at any time point of reperfusion in the dorsal part of the spinal cord. Strong immunoreactivity for NO2-Tyr was selectively induced in large pyramidal motor neurons at 8 hours of reperfusion and was still weakly present until 7 days of reperfusion. (There may be a difference in sensitivity between the two techniques.) These results suggested that protein tyrosine nitration by nitric oxide plays a role in the selective motor neuron cell damage after transient spinal cord ischemia. 相似文献
108.
S Kawasaki H Takizawa T Ohtoshi N Takeuchi T Kohyama H Nakamura T Kasama K Kobayashi K Nakahara Y Morita K Yamamoto 《Canadian Metallurgical Quarterly》1998,42(6):1499-1502
We evaluated the effect of roxithromycin on cytokine production and neutrophil attachment to human airway epithelial cells. Roxithromycin suppressed production of interleukin 8 (IL-8), IL-6, and granulocyte-macrophage colony-stimulating factor. It inhibited neutrophil adhesion to epithelial cells. Roxithromycin modulates local recruitment and activation of inflammatory cells, which may have relevance to its efficacy in airway diseases. 相似文献
109.
K. Ebata H. Wadati M. Takizawa K. Maekawa A. Fujimori A. Chikamatsu H. Kumigashira M. Oshima Y. Tomioka H. Kuwahara Y. Tokura 《Journal of Superconductivity and Novel Magnetism》2007,20(7-8):543-546
We have studied the chemical potential shift and changes in the electronic density of states near the Fermi level (E
F) as functions of temperature and carrier concentration in Pr1−x
Ca
x
MnO3 (PCMO) and Nd1−x
Sr
x
MnO3 (NSMO) by measurements of photoemission spectra. Suppression of the chemical potential shift as a function of carrier concentration
has been observed in PCMO and NSMO near and in the composition range where the CE-type antiferromagnetic charge-ordered (CO)
phase appears at low temperatures. This result indicates that there is charge self-organization on a microscopic scale such
as stripe formation in this composition range. In the ferromagnetic metallic phase of NSMO, we found a large temperature-dependent
chemical potential shift at low temperatures and attributed this to double-exchange mechanism. Suppression of the temperature-dependent
chemical potential shift near Curie temperature was observed, possibly associated with the formation of correlated polarons.
In the valence band near the E
F of PCMO, spectral weight was transferred with hole doping, leading to a finite intensity at E
F even in the paramagnetic insulating phase above the CO phase for x≳0.3, and as the temperature was lowered, a clear gap opening was observed in the CO phase. 相似文献
110.
H Matsukawa A Hara T Ito K Fukui K Sato M Ichikawa M Yoshioka H Seki K Yamataka K Takizawa S Okuda N Shiraga 《Canadian Metallurgical Quarterly》1998,95(11):1229-1234
We treated five patients with severe acute pancreatitis by continuous arterial infusion (CAI) of protease inhibitor, nafamostat mesilate. Arterial injection (AI) of ulinastatin was performed in four cases and AI of antibiotics (IPM/CS) was done in one case, as supplemental therapies of CAI. Abdominal pain disappeared in 7.9 hours on the average, abdominal tenderness disappeared in 5.0 days and laboratory data lately recovered. All five cases treated by these therapies were cured without hemodialysis or surgical treatment in acute phase. AI of ulinastatin through arterial infusion catheter is pharmacokinetically more effective, because it yields a relatively high concentration of the drug at the acting site when compared with that of intravenous injection. Furthermore ulinastatin inhibits different types of protease from nafamostat mesilate. Therefore the clinical effect of CAI of nafamostat mesilate is enhanced by the combined therapy with AI of ulinastatin. It is also suggested that arterial injection of ulinastatin might be effective for the control of abdominal pain and that arterial injection of antibiotics might have an advantage on prevention of infectious pancreatic necrosis. 相似文献