Effect of expansion coefficient difference between machine tool and workpiece to the thermal deformation induced by room temperature change

9th CIRP Conference on High Performance Cutting (HPC 2020)In the precision machining process, ambient temperature is maintained to 20 °C to minimize the thermal deformations. Much energy is consumed to maintain ambient temperature. The use of thermal compensation systems can minimize the energy consumption of room cooling systems. However, the influence of thermal deformation induced by room temperature upon workpieces is not clear. This paper investigates the effect of the linear expansion coefficient difference between a machine tool and workpieces to the thermal deformation induced by room temperature change. Machining experiments are conducted for steel and aluminum workpieces. The results agree with the calculation

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論説(Article

Evaluation of on-machine measuring method for dynamic stiffness of thin-walled workpieces

8th CIRP Conference on High Performance Cutting (HPC 2018)Machining of thin-walled workpieces is a popular issue due to its static and dynamic displacements during machining. It is required to set machining conditions sufficiently considering the vibration characteristics of the workpiece. An automatic on-machine system to measure the dynamic stiffness of the workpiece enables a reliable and frequent measurement. In this study, an on-machine measurement device for workpiece dynamic stiffness is evaluated. The cause of the difference in natural frequency between the on-machine measurement method and impact test is investigated. The influence of the additional mass by a shaker and accelerometer on the natural frequency is investigated using the Rayleigh-Ritz method. A cutting test is conducted to verify whether appropriate cutting conditions can be set from the measurement results of the on-machine dynamic stiffness measurement. The natural frequency difference between the on-machine measurement method and impact test was caused by the additional mass by the contact of the piezoelectric actuator. When the additional mass is 5% or less of the workpiece equivalent mass, the difference in natural frequency was as small as 10 Hz or less. In the cutting test using the workpiece with the sufficiently large mass, the compliance between the on-machine measurement method and impact test was comparable. When the forced vibration was small, the stability limit was correctly estimated from the on-machine dynamic stiffness measurement

Shape analysis of rectus extraocular muscles with age and axial length using anterior segment optical coherence tomography

Purpose This study aimed to evaluate the shape of the extraocular muscles (EOMs) in normal subjects using the en-face images of anterior segment optical coherence tomography (AS-OCT). The EOM insertion and the direction of the muscle fibers were investigated. Subjects and methods A total of 97 healthy normal subjects (194 eyes) at Okayama University Hospital (age, 47.1±21.5 years; range, 8–79 years) participated in the study. A series of 256 tomographic images of the rectus EOMs were captured using the C-scan function of the AS-OCT (CASIA2, TOMEY Co., Japan), and the images were converted to en-face images in multi-TIFF format. The anterior chamber angle to EOM insertion distance (AID) and the angle of the muscle fibers from the insertion site (angle of muscles) were measured from the images. The correlations of AID and angle of muscles with age and axial length were investigated and evaluated. Results AID and angle of muscles were significantly correlated with age or axial length in some EOMs. The AIDs of medial rectus (MR) (P = 0.000) and superior rectus (SR) (P = 0.005) shortened with age. The AIDs of MR (P = 0.001) and inferior rectus (IR) (P = 0.035) elongated with axial length, whereas lateral rectus (LR) (P = 0.013) shortened. The angles of MR (P = 0.001) and LR (P = 0.000) were found to have a more downward direction toward the posterior in older subjects. Conclusion En-face images can be created by AS-OCT, and the shape of the EOMs in normal subjects using these image measurements was available. With the ability to assess the EOMs, AID and angle of muscles are expected give useful information for treating and diagnosing strabismus-related diseases

Breaking the trade-off between fast control and long lifetime of a superconducting qubit

The rapid development in designs and fabrication techniques of superconducting qubits has helped making coherence times of qubits longer. In the near future, however, the radiative decay of a qubit into its control line will be a fundamental limitation, imposing a trade-off between fast control and long lifetime of the qubit. In this work, we successfully break this trade-off by strongly coupling another superconducting qubit along the control line. This second qubit, which we call a Josephson quantum filter (JQF), prevents the qubit from emitting microwave photons and thus suppresses its relaxation, while faithfully transmitting large-amplitude control microwave pulses due to the saturation of the quantum filter, enabling fast qubit control. We observe an improvement of the qubit relaxation time without a reduction of the Rabi frequency. This device could potentially help in the realization of a large-scale superconducting quantum information processor in terms of the heating of the qubit environments and the crosstalk between qubits.Comment: 22 pages, 13 figures, 1 tabl

Incision and suture to maintain motility

Background : Heineke-Mikulicz (HM) strictureplasty is commonly used to treat short stenoses in Crohn’s disease. However, the degree to which intestinal motility is maintained remains unclear. We compared the peristalsis and transport capacity of the sutured intestines with HM configuration and transverse (TS) and longitudinal (LS) incisions. Methods : The intestinal diameter, intraluminal pressure, and bead transit time of each sutured group were compared with that of the non-treatment (NT) group in the isolated proximal colon of rats. Propulsive contractions were induced using hydroxy-α-sanshool (HAS), a constituent of Japanese pepper. Results : There was no change in the intestinal diameter between HM, TS, and NT groups ; however, it was significantly narrowed at the suture site and its distal side in the LS group. After HAS administration, the intestinal diameter at the suture site in the HM group was higher than that in the LS group. The intraluminal pressure was higher and the transit time was shorter in the HM group compared to those in the LS group. Conclusions : The HM configuration, which widens the incision site and distal diameter and shortens the cut surface of the circular muscle in the longitudinal direction, may help maintain basal and HAS-induced intestinal peristalsis and motility