http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Nakashima Hiroaki,Kanemura Tokumi,Satake Kotaro,Ito Kenyu,Ishikawa Yoshimoto,Ouchida Jun,Segi Naoki,Yamaguchi Hidetoshi,Imagama Shiro 대한척추외과학회 2020 Asian Spine Journal Vol.14 No.3
Study Design: Retrospective comparative study.Purpose: We compared clinical and radiographical outcomes after lumbar decompression revision surgery for restenosis by lateral lumbar interbody fusion (LLIF) and posterior lumbar interbody fusion (PLIF).Overview of Literature: Indirect lumbar decompression with LLIF was used to treat degenerative lumbar diseases requiring neural decompression. However, only a few studies have focused on the effectiveness of this technique for restenosis after lumbar decompression.Methods: We retrospectively investigated 52 cases involving lumbar interbody fusions for restenosis with spondylolisthesis after lumbar decompressions; these cases consisted of 15 patients who underwent indirect decompression with LLIF and posterior fixation and 37 patients who underwent the same procedure with PLIF. We compared Japanese Orthopaedic Association (JOA) scores and perioperative complications between groups. The cross-sectional areas of the thecal sac on magnetic resonance imaging were measured before, immediately after, and 2 years after surgery. We conducted statistical analyses using unpaired t -test and Fisher’s exact tests, and a <i>p</i> -value <0.05 was considered statistically significant.Results: The operative time was significantly shorter in the LLIF group than in the PLIF group (115.3±33.6 min vs. 186.2±34.2 min, respectively; <i>p</i> <0.001). In addition, the intraoperative blood loss was significantly lower in the LLIF group than in the PLIF group (58.2±32.7 mL vs. 303.2±140.1 mL, respectively; <i>p</i> <0.001). We found two cases of transient lateral thigh weakness (13.3%) in the LLIF group and five cases of incidental durotomy, one case of deep infection, and one case of neurological deterioration in the PLIF group—resulting in a higher complication incidence (18.9%), although it did not reach (<i>p</i> =0.63). The JOA scores improved significantly in both groups.Conclusions: Indirect decompression using LLIF provided acceptable clinical and radiographical outcomes in patients with restenosis with spondylolisthesis after lumbar decompression; no revision-surgery-specific complications were found. Our results suggest that LLIF is a safe and minimally invasive procedure for revision surgery.
Study on Flow Instability and Countermeasure in a Draft tube with Swirling flow
Nakashima, Takahiro,Matsuzaka, Ryo,Miyagawa, Kazuyoshi,Yonezawa, Koichi,Tsujimoto, Yoshinobu Korean Society for Fluid machinery 2015 International journal of fluid machinery and syste Vol.8 No.4
The swirling flow in the draft tube of a Francis turbine can cause the flow instability and the cavitation surge and has a larger influence on hydraulic power operating system. In this paper, the cavitating flow with swirling flow in the diffuser was studied by the draft tube component experiment, the model Francis turbine experiment and the numerical simulation. In the component experiment, several types of fluctuations were observed, including the cavitation surge and the vortex rope behaviour by the swirling flow. While the cavitation surge and the vortex rope behaviour were suppressed by the aeration into the diffuser, the loss coefficient in the diffuser increased by the aeration. In the model turbine test the aeration decreased the efficiency of the model turbine by several percent. In the numerical simulation, the cavitating flow was studied using Scale-Adaptive Simulation (SAS) with particular emphasis on understanding the unsteady characteristics of the vortex rope structure. The generation and evolution of the vortex rope structures have been investigated throughout the diffuser using the iso-surface of vapor volume fraction. The pressure fluctuation in the diffuser by numerical simulation confirmed the cavitation surge observed in the experiment. Finally, this pressure fluctuation of the cavitation surge was examined and interpreted by CFD.
Hiroaki Nakashima,Tokumi Kanemura,Kotaro Satake,Yoshimoto Ishikawa,Jun Ouchida,Naoki Segi,Hidetoshi Yamaguchi,Shiro Imagama 대한척추외과학회 2019 Asian Spine Journal Vol.13 No.4
Study Design: Prospective cohort study. Purpose: This study aimed to identify risk factors for unplanned second-stage decompression for postoperative neurological deficit after indirect decompression using lateral lumbar interbody fusion (LLIF) with posterior fixation. Overview of Literature: Indirect lumbar decompression with LLIF has been used as a minimally invasive alternative to direct decompression to treat degenerative lumbar diseases requiring neural decompression. However, evidence on the prevalence of neurological deficits caused by spinal canal stenosis after indirect decompression is limited. Methods: This study included 158 patients (mean age, 71.13±7.98 years; male/female ratio, 67/91) who underwent indirect decompression with LLIF and posterior fixation. Indirect decompression was performed at 271 levels (mean level, 1.71±0.97). Logistic regression analysis was used to identify the risk factors for postoperative neurological deficits. The variables included were age, sex, body mass index, presence of primary diseases, diabetes mellitus, preoperative motor deficit, levels operated on, preoperative severity of lumbar stenosis, and preoperative Japanese Orthopedic Association (JOA) score. Results: Postoperative neurological deficit due to spinal canal stenosis occurred in three patients (1.9%). Spinal stenosis due to hemodialysis (p<0.001), ligament ossification (p<0.001), presence of preoperative motor paralysis (p<0.001), low JOA score (p=0.004), and severe canal stenosis (p=0.02) were significantly more frequent in the paralysis group. Conclusions: Severe preoperative canal stenosis and neurological deficit were identified as risk factors for postoperative neurological deterioration caused by spinal canal stenosis. Additionally, uncommon diseases, such as spinal stenosis due to hemodialysis and ligament ossification, increased the risk of postoperative neurological deficit; therefore, in such cases, indirect decompression is contraindicated.
Study on Flow Instability and Countermeasure in a Draft tube with Swirling flow
Takahiro Nakashima,Ryo Matsuzaka,Kazuyoshi Miyagawa,Koichi Yonezawa,Yoshinobu Tsujimoto 한국유체기계학회 2015 International journal of fluid machinery and syste Vol.8 No.4
The swirling flow in the draft tube of a Francis turbine can cause the flow instability and the cavitation surge and has a larger influence on hydraulic power operating system. In this paper, the cavitating flow with swirling flow in the diffuser was studied by the draft tube component experiment, the model Francis turbine experiment and the numerical simulation. In the component experiment, several types of fluctuations were observed, including the cavitation surge and the vortex rope behaviour by the swirling flow. While the cavitation surge and the vortex rope behaviour were suppressed by the aeration into the diffuser, the loss coefficient in the diffuser increased by the aeration. In the model turbine test the aeration decreased the efficiency of the model turbine by several percent. In the numerical simulation, the cavitating flow was studied using Scale-Adaptive Simulation (SAS) with particular emphasis on understanding the unsteady characteristics of the vortex rope structure. The generation and evolution of the vortex rope structures have been investigated throughout the diffuser using the iso-surface of vapor volume fraction. The pressure fluctuation in the diffuser by numerical simulation confirmed the cavitation surge observed in the experiment. Finally, this pressure fluctuation of the cavitation surge was examined and interpreted by CFD.
Modeling o fRebound Phenomenon between Ball and Racket Rubber with Spinning Effect
Akira Nakashima,Yosuke Kobayashi,YukiOgawa,YoshikazuHayakawa 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
We model the rebound phenomenon between a ping-pong ball and the table/racket rubber. In the model between the ball and racket rubber, it is assumed that the kinetic energy of the contact velocity is stored as the potentialen ergy due to the elasticity of the rubber. This assumption leads to that the impulse in the horizontal direction is propor-tional to the contactve locity. The vertical and horizontal COR in the models of the table and rubber are identified with the measured velocity and spin of the ball by high-speed vision sensors. The models are verified by other experimental data.
A method for extraction of arbitrary figure using one-dimensional histogram
Shota Nakashima,Makoto Miyauchi,Seiichi Serikawa 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10
An extraction of a specific figure in image has basic problems in intelligent image sensing. The generalized Hough transform (GHT) is the representative method to extract arbitrary figures which are rotated and enlarged or reduced. Many the improvement models were also proposed. However, for extraction of arbitrary figures, it takes much processing time and needs much memory space. In addition, it is impossible to apply the GHT to figures including branches. For an improvement of the problems, a new method to extract arbitrary figure using one-dimensional histogram is proposed in this study. The method utilizes the Polytope method which is one of minimization algorithms. For the extraction of figures, one-dimensional histogram is used. The histogram has two characteristics. (1) The distribution of histogram changes if the parameters representing figure changes. (2) The best parameters are gotten, if the value of most frequency of histogram becomes maximum. Therefore, by using the Polytope method, the best parameters are searched so that the maximum value of most frequency can be maximum. In comparison with conventional method, it is understood that memory space is very small, processing time is very short and figures including branches can be extracted. In addition, this method is effective for an extraction of arbitrary figure with different aspect ratio.