Performance and Internal Flow Condition of Mini Centrifugal Pump with Splitter Blades

Toru Shigemitsu,Junichiro Fukutomi,Kensuke Kaji,Takashi Wada 한국유체기계학회 2013 International journal of fluid machinery and syste Vol.6 No.1

Mini centrifugal pumps having a diameter smaller than 100mm are employed in many fields. But the design method for the mini centrifugal pump is not established because the internal flow condition for these small-sized fluid machines is not clarified and conventional theory is not suitable for small-sized pumps. Therefore, mini centrifugal pumps with simple structure were investigated by this research. Splitter blades were adopted in this research to improve the performance and the internal flow condition of mini centrifugal pump which had large blade outlet angle. The original impeller without the splitter blades and the impeller with the splitter blades were prepared for an experiment. The performance tests are conducted with these rotors in order to investigate the effect of the splitter blades on performance and internal flow condition of mini centrifugal pump. On the other hand, a three dimensional steady numerical flow analysis is conducted with the commercial code (ANSYS-CFX) to investigate the internal flow condition in detail. It is clarified from experimental results that the performance of the mini centrifugal pump is improved by the effect of the splitter blades. Blade-to-blade low velocity regions are suppressed in the case with the splitter blades and total pressure loss regions are decreased. The effects of the splitter blades on the performance and the internal flow condition are discussed in this paper.

Review of Buckling-Restrained Brace Design and Application to Tall Buildings

Takeuchi, Toru,Wada, Akira Council on Tall Building and Urban Habitat Korea 2018 International journal of high-rise buildings Vol.7 No.3

Buckling-restrained braces (BRBs) are widely used as highly ductile seismic devices, with the first building using BRBs completed in 1989 in Tokyo, and thousands more now in Japan, USA, Taiwan, China, New Zealand and other countries. Although design codes of several countries specify BRB performance criteria, detailed design provisions are not necessarily provided, as BRBs are typically treated as a manufactured device. This paper briefly reviews the early history of BRB research and offers state-of-the-art views on the design criteria required to obtain stable and reliable performance. Representative project examples and up-to-date studies relevant to tall buildings are summarized.

Performance and Internal Flow Condition of Mini Centrifugal Pump with Splitter Blades

Shigemitsu, Toru,Fukutomi, Junichiro,Kaji, Kensuke,Wada, Takashi Korean Society for Fluid machinery 2013 International journal of fluid machinery and syste Vol.6 No.1

Mini centrifugal pumps having a diameter smaller than 100mm are employed in many fields. But the design method for the mini centrifugal pump is not established because the internal flow condition for these small-sized fluid machines is not clarified and conventional theory is not suitable for small-sized pumps. Therefore, mini centrifugal pumps with simple structure were investigated by this research. Splitter blades were adopted in this research to improve the performance and the internal flow condition of mini centrifugal pump which had large blade outlet angle. The original impeller without the splitter blades and the impeller with the splitter blades were prepared for an experiment. The performance tests are conducted with these rotors in order to investigate the effect of the splitter blades on performance and internal flow condition of mini centrifugal pump. On the other hand, a three dimensional steady numerical flow analysis is conducted with the commercial code (ANSYS-CFX) to investigate the internal flow condition in detail. It is clarified from experimental results that the performance of the mini centrifugal pump is improved by the effect of the splitter blades. Blade-to-blade low velocity regions are suppressed in the case with the splitter blades and total pressure loss regions are decreased. The effects of the splitter blades on the performance and the internal flow condition are discussed in this paper.

E-Isolation : High-performance Dynamic Testing Installation for Seismic Isolation Bearings and Damping Devices

Yoshikazu Takahashi,Toru Takeuchi,Shoichi Kishiki,Yozo Shinozaki,Masako Yoneda,Koichi Kajiwara,Akira Wada Council on Tall Building and Urban Habitat Korea 2023 International journal of high-rise buildings Vol.12 No.1

Seismic isolation and vibration control techniques have been developed and put into practical use by challenging researchers and engineers worldwide since the latter half of the 20th century, and after more than 40 years, they are now used in thousands of buildings, private residences, highways in many seismic areas in the world. Seismic isolation and vibration control structures can keep the structures undamaged even in a major earthquake and realize continuous occupancy. This performance has come to be recognized not only by engineers but also by ordinary people, becoming indispensable for the formation of a resilient society. However, the dynamic characteristics of seismically isolated bearings, the key elements, are highly dependent on the size effect and rate-of-loading, especially under extreme loading conditions. Therefore, confirming the actual properties and performance of these bearings with full-scale specimens under prescribed dynamic loading protocols is essential. The number of testing facilities with such capacity is still limited and even though the existing labs in the US, China, Taiwan, Italy, etc. are conducting these tests, their dynamic loading test setups are subjected to friction generated by the large vertical loads and inertial force of the heavy table which affect the accuracy of measured forces. To solve this problem, the authors have proposed a direct reaction force measuring system that can eliminate the effects of friction and inertia forces, and a seismic isolation testing facility with the proposed system (E-isolation) will be completed on March 2023 in Japan. This test facility is designed to conduct not only dynamic loading tests of seismic isolation bearings and dampers but also to perform hybrid simulations of seismically isolated structures. In this paper, design details and the realization of this system into an actual dynamic testing facility are presented and the outcomes are discussed.

Role of Dispersion State of Ti Species in Deactivation of MgCl2-Supported Ziegler-Natta Catalysts

Toshiaki Taniike,Toru Wada,Iku Kouzai,Shougo Takahashi,Minoru Terano 한국고분자학회 2010 Macromolecular Research Vol.18 No.9

The deactivation behaviors of TiCl3/MgCl2 model catalysts with molecularly dispersed TiCl3 were investigated to clarify the role of the dispersion state of the Ti species in the deactivation of MgCl2-supported Ziegler-Natta (ZN) catalysts for propylene and ethylene polymerization. The propylene and ethylene polymerization activities of clustered Ti species supported on MgCl2 were approximately one tenth of those of isolated Ti species, which is indicative of the significance of the aggregation of Ti species in the deactivation of ZN catalysts for olefin polymerization. Moreover, the time-course depression of monomer consumption for the clustered Ti species was slower than that for the isolated Ti species in propylene polymerization, whereas the dispersion state barely affected the depression rate in ethylene polymerization. The reduction rate of the Ti species was concluded to be important for the time-course depression of propylene consumption, whereas ethylene polymerization was insensitive to the oxidation state of the Ti species.

Severe C8 or T1 Symptoms after Cervical Laminoplasty and Related Factors: Are There Any Differences between C3–C6 Laminoplasty and C3–C7 Laminoplasty?

Hitoshi Kudo,Kazunari Takeuchi,Toru Yokoyama,Yoshihito Yamasaki,Kanichiro Wada,Gentaro Kumagai,Toru Asari,Hironori Otsuka,Yasuyuki Ishibashi 대한척추외과학회 2019 Asian Spine Journal Vol.13 No.4

Study Design: Retrospective study. Purpose: We experienced the situation wherein some patients had new-onset pain or dysesthesia around the ring and little fingers (C8 symptom) or ulnar aspect of the forearm (T1 symptom) after cervical laminoplasty (LP). We investigated the incidence and the cause of new C8 or T1 symptoms and the clinical outcomes after C3–C6 LP or C3–C7 LP. Overview of Literature: There were some reports regarding complications after cervical LP. However, there was no report regarding C8 or T1 symptoms after cervical LP. Methods: Among the 33 patients enrolled in this study, 11 and 22 patients were treated with C3–C6 LP and C3–C7 LP, respectively. We prospectively evaluated C8 or T1 symptoms daily postoperatively for 1 week. The distance of the posterior spinal cord shifting and posterior subarachnoid space from C2 to T1 was measured by T2-weighted midsagittal magnetic resonance imaging (MRI). We evaluated pre- and postoperative axial neck pain, Japanese Orthopaedic Association (JOA) score, and JOA score improvement rate. Results: C8 or T1 symptoms occurred in five and three patients with C3–C6 LP (45.5%) and C3–C7 LP (13.6%), respectively. The distance of the posterior subarachnoid space in C3–C6 LP at C7 was significantly shorter than that in C3–C7 LP at T1 on MRI 24 hours postoperatively (p=0.0448). Postoperative axial neck pain, pre- and postoperative JOA scores, and JOA score improvement rate were not significantly different. Conclusions: The incidence of C8 or T1 symptoms in C3–C6 LP was higher than that in C3–C7 LP. C8 or T1 symptoms would be caused by the posterior fila radicularia and spinal cord impingement on the intact lower end of the lamina.

Association between Preoperative Urine Culture and Urinary Tract Infection after Spinal Surgery

Nagaoki Toshihide,Kumagai Gentaro,Wada Kanichiro,Tanaka Sunao,Asari Toru,Ishibashi Yasuyuki 대한척추외과학회 2023 Asian Spine Journal Vol.17 No.1

Study Design: This is a retrospective study.Purpose: This study assessed risk factors accounting for urinary tract infections (UTIs) to determine whether preoperative asymptomatic UTI (aUTI) could be used to predict UTIs in patients after spinal surgery.Overview of Literature: UTI is a spinal surgery complication that increases the incidence of surgical site infections. However, the risk factors for UTIs after spinal surgery remain unclear.Methods: This study included 509 (mean age, 54.5 years; 239 males and 270 females) patients who underwent posterior spine surgery at the department of the current study. First, clean catch urine was collected, after which a urine culture was performed for all patients before surgery. Preoperative detection of the aUTI (>105 colony-forming units/mL) rate was then determined. Subsequently, risk factors for postoperative UTI were evaluated using logistic regression analysis with the following as independent variables: age, sex, obesity, diabetes, spinal cord tumor, the preoperative Japanese Orthopedic Association (JOA) score, JOA-bladder function, preoperative urine culture positivity, aUTI, preoperative Escherichia coli detection, the postoperative catheter placement period, instrumentation, number of surgical levels, surgery duration, and blood loss.Results: The preoperative aUTI and postoperative UTI incidences were 8.1% and 4.1%, respectively. Furthermore, multivariate logistic analysis showed that the risk factor for postoperative UTI was preoperative aUTI (odds ratio, 4.234; 95% confidence interval, 1.532–11.702; p=0.005).Conclusions: Preoperative aUTI is a risk factor for UTI in patients after spinal surgery.

Effects of Molecular Dispersion State of Surface Ti Species on Ethylene-Propylene Copolymerization with TiCl3-based Ziegler-Natta Model Catalyst

Toshiaki Taniike,Shougo Takahashi,Toru Wada,Iku Kouzai,Minoru Terano 한국고분자학회 2010 Macromolecular Research Vol.18 No.9

The dispersion state of surface Ti species is one of the most important factors affecting the polymerization properties of MgCl2-supported heterogeneous Ziegler-Natta catalysts. In this paper, ethylene-propylene copolymerization was carried out using a novel Ziegler-Natta model catalyst with “isolated” and “clustered” TiCl3 molecules on MgCl2. At a lower ethylene/propylene feed ratio, the dispersion state of the Ti species strongly affected both the composition and sequence distribution of the copolymers. The “isolated” Ti species gave a relatively random copolymer, and clustering of Ti species enhanced the bulkiness. The addition of an external donor basically deteriorated the random copolymerization character of the “isolated Ti species but the degree of deterioration depended on the type of donors. On the other hand, the balance between the monomer feed and consumption dominated the copolymerization performance at a higher ethylene/propylene feed ratio to obscure the effects of the dispersion state.

Design of Seismic Isolated Tall Building with High Aspect-Ratio

Kikuchi, Takeshi,Takeuchi, Toru,Fujimori, Satoru,Wada, Akira Council on Tall Building and Urban Habitat Korea 2014 International journal of high-rise buildings Vol.3 No.1

When seismic isolation system is applied to high aspect-ratio (height/wide-ratio) steel structures, there are several problems to be taken into consideration. One is lifting up tensile force on the isolation bearing by overturning moment caused by earthquake. Another is securing building stiffness to produce seismic isolation effects. Under these conditions, this paper reports the structural design of high-rise research building in the campus of Tokyo Institute of Technology. With the stepping-up system for the corner bearings, the narrow sides of single span framework are designed to concentrate the dead load as counter-weight for the tensile reaction under earthquake. Also we adopted concrete in-filled steel column and Mega-Bracing system covering four layers on north & south framework to secure the horizontal stiffness of the building.