ABSTRACT
The accurate modeling of the complex dynamic stiffness of inflated rubber diaphragms in pneumatic springs is necessary for an efficient design of vibration isolation tables for precision instruments, such as optical devices and nano-scale equipment. In addition to pressurized air, rubber diaphragms, essentially employed for the prevention of air leakage, make a significant contribution to the total complex stiffness. To reflect the effect of the dynamic stiffness of the inflated rubber diaphragm on the total complex stiffness during the initial design or design improvement stage, it is desirable to predict the complex stiffness of the inflated rubber diaphragm beforehand. In this paper, an estimation method for the complex stiffness of inflated rubber diaphragms using the commercial finite element method (e.g., ABAQUS) is proposed. The proposed method reflects their dynamic characteristics under the large static deformation by the Mooney-Rivlin and Morman's constitutive equations. The results of comparison with experimental results indicate that the predictions obtained by the proposed method are congruent with the experimental values of the diaphragm.
ABSTRACT
A vibration isolator embedded in precision equipment, such as a scanning electron microscope (SEM), wafer inspection equipment, and nanoimprint lithography equipment, play a critical role in achieving the maximum performance of the equipment during the fabrication of nano/micro-electro-mechanical systems. In this study, the factors that degrade the performance of SEM equipment with isolation devices are classified and discussed, and improvement measures are proposed from the viewpoints of the measured image patterns and vibrations in comparison with the relevant vibration criteria. In particular, this study quantifies the image patterns measured using SEMs, and the results are discussed along with the measured vibration. A guide for the selection of mounting equipment is presented by performing vibration analysis on the lower mount of the dual elastic mount configuration applied to the SEM, as well as the image patterns analyzed with that configuration. In addition, design modifications for the mount and its arrangement are suggested based on impact tests and numerical simulations.
ABSTRACT
The air-balloon can effectively neutralize hull excitations induced by the propeller cavitation. For the design, it is essential to derive the destructive frequency of an oblate spheroidal air-bubble, which is elaborated on in this paper. Beginning with the exact modal-series solution proposed by Yeh [Ann. Phys. 468, 53-61 (1964)], an approximated form of the scattered pressure is set up by assuming that the acoustic wavelength is much larger than the size of the balloon in the low frequency ranges. An algebraic formula for the destructive frequency can then be written as a function of the resonance frequency and a spatial variable. It is well known that the resonance frequency of a deformed bubble is higher than that of an ideal spherical one with the same volume. In addition to this, the current investigation puts an emphasis on the fact that asphericity induces a more severe shift of the destructive frequency than the resonance frequency, and that its effect needs to be reflected in the balloon design.
ABSTRACT
This study was conducted to evaluate the efficacy and safety of the combination of mitomycin-C (MMC) and S-1 as third-line chemotherapy for patients with advanced colorectal cancer (CRC) showing resistance to irinotecan- and oxaliplatin-containing regimens. Patients were recruited into the study from January 2009 and 10 patients were enrolled for 10 months. However, since no patients had shown a response by 10 months, the study was terminated early according to the protocol. MMC 7 mg/m(2) was administered intravenously on day 1 every 6 weeks in the first 4 cycles. S-1 was administered twice daily at 35 mg/m(2), within 1 h of meals on days 1-14. Following a rest for 7 days, S-1 was administered again on days 22-35, followed by a 7-day rest. A total of 14 cycles were delivered for 10 patients. All 10 patients were assessable for response. A total of 3 patients (30%) had stable disease and the remaining 7 showed disease progression. With a median follow-up of 7 months, the median overall survival was 10.5 months. Grade 3-4 myelotoxicities included neutropenia in two patients, anemia in two and thrombocytopenia in one. Grade 1-2 nausea and vomiting developed in 5 patients. One patient experienced grade 3 diarrhea. Grade 1-2 hand-foot syndrome occurred in 4 patients. In conclusion, the combination of MMC and S-1 as third-line chemotherapy in patients with advanced CRC appears to be well tolerated but has poor activity.
ABSTRACT
BACKGROUND AND OBJECTIVE: Currently there are few data available regarding the use of impulse oscillometry parameters to assess airflow obstruction during standardized methacholine challenge testing. METHODS: Methacholine challenge tests were performed using impulse oscillometry and conventional spirometry in 64 healthy and 39 asthmatic children, in order to determine airway resistance (R) and reactance (X) at frequencies of 5-35 Hz, as well as FEV(1). RESULTS: Baseline R and X were significantly different between the healthy and asthmatic children, with the most discriminating parameter being resistance at 5 Hz (R5). In asthmatic children BHR was well demonstrated by FEV(1), X5 and X10, but not by R5. However, when the actual R5 values obtained in this study were compared with the predicted values, there appeared to be differences in the lung function measures that corresponded to varying methacholine concentrations. In addition, the PC20_FEV(1) and PC70_X5 were significantly more sensitive than other parameters for methacholine challenge testing. CONCLUSIONS: Measuring resistance at 5 Hz using impulse oscillometry facilitates significant differentiation of baseline lung function between asthmatic and healthy children. Additionally, X may be a suitable replacement for PC20 in methacholine challenge testing.
