A numerical study of aerodynamics in a deteriorated gas turbine was carried out. In the present study, a hybrid method of CFD simulation and heat balance analysis were used to estimate entire performance of the gas turbine cycle and local flow characteristics in the turbine section. Using this analysis method, flows in a deteriorated gas turbine were simulated under an operating condition, which was designated using the same procedure with that used in a real power plant. In our previous study, the degradation of the gas turbine performance due to blades deterioration had been observed. In the present study, flow patterns were observed and mechanisms underlying the degradation of the gas turbine performance were discussed in detail. Influences of two kinds of deterioration on flow patterns were examined: the first was thinning of nozzle guide vanes in the first stage and the second was increase of rotor tip gap in the first stage. The results showed that the deterioration of nozzle guide vanes leaded to decrease of the Mach number through the nozzle, and this leaded to increase of the turbine isentropic efficiency due to decrease of the friction loss. The increase in the rotor tip gap affected a loss generation of the following stage. Changes of flow patterns and its effects were discussed varying operating points of a gas turbine.
Clamp-on steam flowmeter was is developed by ultrasonic beam focusing technique. In the conventional tuft method, three individual sensors are arranged as receivers to estimate the sound pressure distribution. However, the alignment and the sensitivity of the sensors are required to improve. Therefore, focusing sensor array was newly manufactured. Besides, the signal to noise ratio was improved by applying the damping material which attenuates the guided wave. Then the steam flowrate measurement experiment was conducted by using the developed ultrasonic sensors and damping material. The results reveal the possiblility of steam flowrate measurement by ultrasonic tuft method.
Recently, having encountered a case of multiple myeloma, we have described about her X-ray findings, results of clinical examination and given our comments on differentiated findings with these of other diseases appearing in the literature referred to.
We studied the relationship between the contrast characteristics of barium suspension and timing of exposure.We poured several kinds of barium preparations on the phantom manufactured by ourselves, and took X-ray pictures continuously by a DSA system. We analyzed each of the characteristics of the contrast. The time which was reguired for the contrast to reach the peak (Contrast Peak Time; CPT) was unrelated with the kind of barium preparations used. It depended on the viscosity of the contrast media and the angle of the phantom. Viscosity was correlated with CPT. CPT was 3 to 6 seconds at an angle of 15 degrees, and 1.5 to 4 seconds at an angle of 30 degrees.We can refer to these findings to decide the density of barium suspension and to get timely exposure.
The effectiveness of the extended-cycle process, in which processing time is longer than the manugacturer's recommendation, was investigated using four mammographic films, Konica New CM, Fuji UM-MA HC, Kodak Min-R 2000, and Kodak Min-R M, Fuji UR-2, a double-emulsion film, was used as a control. The sensitometric strips exposed by a sensitometer were processed in different combinations of developing temperatures ranging from 28 to 36℃, processing times from 45 to 210 sec chemicals, Konica XD-90C, Fuji RD-5 and Kodak RP X-Omat. Those characteristics(average gradient, relative speed, base plus fog)obtained from characteristic curves were evaluated for the different developing temperatures, times and chemicals. Fuji UR-2 was scarcely affected, while mammographic films were greatly affected in the different combinations without an increase in base plus fog. For New CM, UM-MA HC and Min-R M, the average gradient and relative speed increased as developing temperature increased and developing time was extended, but the increases were limited with the combination of 36℃ and 210 sec for New CM and UM-MA HC. For Min-R 2000, the average gradient was almost constant, and the relative speed increased like the other three mammographic films. Changes in average gradient and relative speed due to chemical variations showed increases or decreases from 6% to 9% compared with Konica chemical. These results suggested that the extended-cycle process for the above mammographic films has the possibility to contribute to dose reduction and advancement of contrast on mammography.
Technetium-99m phosphate tracers, introduced in.1971 as bone-scanning agents, have been found useful in the detection of bone lesions".The accumulation of bone-seeking radiopharmaceuticals in extraosseous lesions has been reported in patients with myocardial or cerebral infarction, or some soft-tissue tumor"-24.Primary pulmonary lung cancer which had concentrated fl9"Tc-labeled phosphate did not refer to the histological type of cancer.We observed Tc-99m diphosphonate uptake in small cell carcinoma of the lung.
Determining the absorbed dose distributions in phantoms for X-ray beams of high-energy medical linear accelerators (LINAC) is an important task in the quality control of a system. Although optical imaging of water during irradiation of X-ray beams from a LINAC is a promising method, depth dose profiles show underestimation in the deeper parts of the water, mainly due to the angular dependency of Cerenkov-light produced in water. To solve this problem, the authors change camera angles from 0 degree to 10 degrees and obtain optical images with a high-sensitivity cooled charge coupled device (CCD) camera during X-ray beam irradiation. Furthermore, the authors calculate the Cerenkov-light distributions with different camera angles using Monte Carlo simulation and the obtained depth profiles. Then, these depth profiles are evaluated and compared with those of a planning system. In both measured and simulated distributions, the light intensity increases as the angle increases. The measured depth profile of 10 degrees was nearly identical to the planning system. The percentage differences of depth profile between the measured optical image at the angle of 10 degrees and the planning system was -1.7 % at 100 mm depth, and the average difference was 0.8 %. We conclude that optical imaging with that angle is a promising method for reducing the error due to the angular dependency of Cerenkov-light.
For energy efficient operation of steam facilities, it is often required to measure a wide range of vapor flow rate. Clamp-on flowmeters are advantageous when it is necessary to measure vapor flow rates in various locations within one facility. On the other hand, ultrasonic flowmeters are well-known for their wide range of measurable gas flow rate. In the past, a clamp-on ultrasonic gas flow meter was developed, however there was a need for a damping material able to propagate ultrasonic wave through high temperature vapor pipe. The development of a clamp-on ultrasonic steam flowmeter with a high temperature endurance silicone rubber damping material is presented here. Silicone with high loss modulus has demonstrated good damping characteristic of ultrasonic wave. Using this newly developed flowmeter, 25A SGP 0.3 MPa steam flow can be measured up to 28m/s velocity.
医療の高度化に伴い,近年では長時間のⅩ線透視を行うInterventional Radiology(IVR)手技が頻繁に行われ,副作用としての難治性放射線皮膚障害例の報告が増加している｡確定的影響である放射線皮膚障害はしきい値を超えると発症し,線量に依存して障害の程度が重篤となるため,患者被曝線量の測定が重要である｡しかし,IVRでは照射部位が多彩で,焦点-皮膚間距離が不安定なため,その測定方法は確立されていない｡本研究では,近年IVR等低エネルギー線量測定用フイルムとして開発されたCAFCHROMIC XR TYPE T
について性能評価を行い,患者皮膚入射面の被曝線量測定への応用の可能性について検討した｡その結果,線量特性,線質特性,ネット値の安定性に良好な特性を示し,臨床に使用可能であったので報告する｡
