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Study on Improvement in Resolution of Synthetic Aperture Sonar Using Spatial Filter
Kazuya Watanabe,Satoshi Honda,Takao Sawa 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
A synthetic aperture sonar(SAS) achieving high azimuth resolution at long range has been studied for seafloor mapping. Images obtained from SAS, however, are not sufficient to acquire detailed information of seabed. Hence, in order to obtain the sharp image of the object, it is necessary to improve the resolution of the images. Beam forming techniques steer direction with the greatest sensitivity. We propose an application of beam forming to SAS for the accuracy improvement of imagery. Computer simulation and real data analysis show that an improvement of azimuth resolution is achieved and the reare differences between simulation rsults and real data results.
Kazuya Kitamura,Narihito Nagoshi,Osahiko Tsuji,Satoshi Suzuki,Satoshi Nori,Eijiro Okada,Mitsuru Yagi,Morio Matsumoto,Masaya Nakamura,Kota Watanabe 대한척추신경외과학회 2022 Neurospine Vol.19 No.1
Objective: The purpose of our study was to investigate the risk factors of remnant tumor growth after incomplete resection (IR) of cervical dumbbell-shaped schwannomas (DS). Methods: Twenty-one patients with IR of cervical DS with at least 2 years of follow-up were included and were divided into 2 groups: the remnant tumor growth (G) (n = 10) and no growth (NG) (n = 11) groups. The tumor location in the axial plane according to Toyama classification, the location of the remnant tumor margin, and the tumor growth rate (MIB1 index) index were compared. Results: No significant differences in Toyama classification and MIB-1 index were found. Age was significantly higher in the G group (61.4 years vs. 47.6 years; p = 0.030), but univariate logistic regression analysis revealed little correlation to the growth (odds ratio [OR], 1.08; 95% confidence interval [CI], 1.001–1.166; p = 0.047). Seventeen patients (9 in the G and 8 in the NG group) underwent the posterior one-way approach, and significant differences in the location of the remnant tumor margin were confirmed: within the spinal canal in 1 and 0 case, at the entrance of the intervertebral foramen in 7 and 1 cases, and in the foramen distal from the entrance in 1 and 7 cases, in the G and NG groups, respectively (p = 0.007). The proximal margin was identified as a significant predictor of the growth (OR, 56.0; 95% CI, 2.93–1,072; p = 0.008). Conclusion: Remnant tumors with margins distally away from the entrance of the foramen were less likely to grow after IR of cervical DS.
Kazuya Hirai,J Watanabe,S Kinoshita 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.51 No.2I
A method for selective phonon generation using linearly chirped femtosecond pulses is presented. This method is particularly suitable to investigate the phonon dynamics in a wide frequency range because the center frequency and the width of the excited phonon modes can be varied only by changing the separation of the two pump pulses and the distance of the grating pair. Using frequency-domain four-wave mixing spectroscopy, we will show that phonon modes with quite a narrow width are actually excited within the low-frequency Raman region of liquid carbon disulfide, even though the pump pulse has a broad spectral width.
Hirohisa Watanabe,Yuichi Riku,Kazuhiro Hara,Kazuya Kawabata,Tomohiko Nakamura,Mizuki Ito,Masaaki Hirayama,Mari Yoshida,Masahisa Katsuno,Gen Sobue 대한파킨슨병및이상운동질환학회 2018 Journal Of Movement Disorders Vol.11 No.3
Multiple system atrophy (MSA) is an adult-onset, progressive neurodegenerative disorder. Patients with MSA show various phenotypes during the course of their illness, including parkinsonism, cerebellar ataxia, autonomic failure, and pyramidal signs. Patients with MSA sometimes present with isolated autonomic failure or motor symptoms/ signs. The median duration from onset to the concomitant appearance of motor and autonomic symptoms is approximately 2 years but can range up to 14 years. As the presence of both motor and autonomic symptoms is essential for the current diagnostic criteria, early diagnosis is difficult when patients present with isolated autonomic failure or motor symptoms/signs. In contrast, patients with MSA may show severe autonomic failure and die before the presentation of motor symptoms/signs, which are currently required for the diagnosis of MSA. Recent studies have also revealed that patients with MSA may show nonsupporting features of MSA such as dementia, hallucinations, and vertical gaze palsy. To establish early diagnostic criteria and clinically definitive categorization for the successful development of disease-modifying therapy or symptomatic interventions for MSA, research should focus on the isolated phase and atypical symptoms to develop specific clinical, imaging, and fluid biomarkers that satisfy the requirements for objectivity, for semi- or quantitative measurements, and for uncomplicated, worldwide availability. Several novel techniques, such as automated compartmentalization of the brain into multiple parcels for the quantification of gray and white matter volumes on an individual basis and the visualization of α-synuclein and other candidate serum and cerebrospinal fluid biomarkers, may be promising for the early and clinically definitive diagnosis of MSA.
Jun-ichi Itoh,Kazuya Kawai,Koroku Nishizawa,Hiroki Watanabe 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
This paper proposes a design method of the flux-axis angular speed estimation using induced voltage in a speed sensor-less field oriented control for induction motor (IM) drive systems. In this method, the d-axis induced voltage is regulated to zero by a feedback control to estimate the fluxaxis angular speed. A low pass filter (LPF) is necessary in this estimation to avoid the recursive calculation. In this paper, the design method of compensation gain kpem and the cut-off angular frequency of LPF ωlpf are considered. As a result, the relation between kpem, ωlpf, convergence time of the d-axis induced voltage have a match to the equation and designed model in this paper. Furthermore, the maximum error between the simulation and estimated results of the time constant of the flux-axis angular speed introduced due to LPF is 3.7% when ωlpf is 200 rad/s. As the experimental results, when a torque step of 100% is applied to the induction motor, the convergence time of the motor speed is 1.6 s as the worst case with kpem set as 2.0 p.u. and the cut-off angular frequency set as 1000 rad/s. However, if kpem is set as 2.0 p.u. and ωlpf is set as 400 rad/s, the convergence time of the motor speed is 0.43 s as the best case, which is reduced by 73.1% compared to the worst case. As the result, kpem should decide by the target steady-state error, lpf should bigger than the cut-off angular frequency of the PI controller ωASR. Where, if the ωlpf is high, the convergence time of the motor speed is high.
Washio, Masakazu,Mori, Mitsuru,Mikami, Kazuya,Miki, Tsuneharu,Watanabe, Yoshiyuki,Nakao, Masahiro,Kubo, Tatsuhiko,Suzuki, Koji,Ozasa, Kotaro,Wakai, Kenji,Tamakoshi, Akiko Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.11
Background: Cigarette smoking is the largest single recognized cause of human cancers. In Western countries, many epidemiologists have reported risk factors for kidney cancer including smoking. However, little is known about the Japanese population. Materials and Methods: We evaluated the association of smoking with the risk of kidney cancer death in the Japan Collaborative Cohort (JACC) Study. Participants included 46,395 males and 64,190 females. The Cox proportional hazards model was used to determine age-and-sex adjusted relative risks. Results: A total of 62 males and 26 females died from kidney cancer during the follow-up of 707,136 and 1,025,703 person-years, respectively. Heavy smokers (Brinkman index >1200), fondness of fatty foods, hypertension, diabetes mellitus (DM), and obesity were suggested to increase the risk of renal cell carcinoma while walking was suggested to decrease the risk. Even after controlling for age, sex, alcohol drinking and DM, heavy smoking significantly increased the risk. Conclusions: The present study suggests that six factors including smoking may increase and/or reduce the risk of kidney cancer in the Japanese population. Because of the small number of outcomes, however, we did not evaluate these factors after adjusting for all possible confounding factors. Further studies may be needed to confirm the findings in this study.
Washio, Masakazu,Mori, Mitsuru,Mikami, Kazuya,Miki, Tsuneharu,Watanabe, Yoshiyuki,Nakao, Masahiro,Kubo, Tatsuhiko,Suzuki, Koji,Ozasa, Kotaro,Wakai, Kenji,Tamakoshi, Akiko Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.7
Background: The incidence of bladder cancer is lower in Asian than in Western countries. However, the crude incidence and mortality of bladder cancer have recently increased in Japan because of the increased number of senior citizens. We have already reported risk factors for urothelial cancer in a large population-based cohort study in Japan (JACC study). However, we did not evaluate the cancer risk in the upper and lower urinary tract separately in our previous study. Materials and Methods: Here we evaluated the risk of cancer death in the upper and lower urinary tracts, separately, using the database of the JACC study. The analytic cohort included 46,395 males and 64,190 females aged 40 to 79 years old. The Cox proportional hazard model was used to determine hazard ratios and their 95% confidence intervals. Results: Current smoking increased the risk of both upper and lower urinary tract cancer deaths. A history of kidney disease was associated with an increased risk of bladder cancer death, even after controlling for age, sex and smoking status. Conclusions: The present study confirmed that current smoking increases the risk of both upper and lower urinary tract cancer deaths and indicated the possibility that a history of kidney disease may be a risk factor for bladder cancer death in the Japanese population.
Risk Factors for Renal Cell Carcinoma in a Japanese Population
Washio, Masakazu,Mori, Mitsuru,Mikami, Kazuya,Miki, Tsuneharu,Watanabe, Yoshiyuki,Nakao, Masahiro,Kubo, Tatsuhiko,Suzuki, Koji,Ozasa, Kotaro,Wakai, Kenji,Tamakoshi, Akiko Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.21
The incidence of renal cell carcinoma (RCC) is high in Western and Northern Europe and North America, and low in Asia. Although the incidence of RCC in Japan is lower than the rates in the other industrialized countries, there is no doubt that it is increasing. In this paper, we would like to introduce the summary of findings of JACC study, which evaluate the risk factors for RCC in a Japanese population. JACC study suggests nine risk factors (i.e., smoking, obesity, low physical activity, hypertension, diabetes mellitus, kidney diseases, beef, fondness for fatty food and black tea) and one preventive factor (i.e., starchy roots such as taro, sweet potato and potato) in a Japanese population. In Japan, however, drinking black tea may be a surrogate for westernized dietary habits while eating starchy roots may be a surrogate for traditional Japanese dietary habits. Further studies may be needed to evaluate risk factors for RCC because the number of cases is small in our studies.