Results 1 - 10 of 176201
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[en] An automatic controller that uses the model predictive control (MPC) method is being developed for automatic load follow operation. As described in Ref. a system identification method is important in the MPC method because MPC is based on a system model produced by system identification. There are many models and methods of system identification. In this study, AutoRegressive eXogenous (ARX) model was selected from among them, and the recursive least square (RLS) method and least square (LS) method associated with this model are used in a comparative performance analysis
[en] Neutron detectors for flight test applications use either a photomultiplier tube (PMT) or a silicon photodiode as a light detector to monitor the light output of scintillation materials. Silicon diodes lack sensitivity, so PMT's are used in most low flux neutron applications. The SA 1690 is presently the only Sandia qualified PMT. It has a complex temperature response requiring the selection of a temperature compensation circuit during assembly to meet accuracy requirements. Results are presented of a study which was performed to evaluate the temperature stability of two other light detectors and to compare the results with the performance of the SA 1690
[en] This study is to provide accurate information as medical imaging equipment to check for the presence of body disease US equipment. We investigated the status of medical US equipment performance in Daegu and criteria US phantom (ATS-539) for US equipment performance measurements. The results in this study, 1. US phantom measurement results: The test passed rate were 88.6% and the failed rate were 11.4%. 2. The difference between the group of mean and the pass/failed groups were statistically significant. Focal zone and 4 mm functional resolution in the two items that are not present the passing standard. 3. The difference was statistically significant number of years and used equipment and pass the failed equipment (4.13 vs 7.25 years). We investigated the performance status of US equipment used in the clinical area in Daegu. The basis for the two items are not present this proposed passing standard. Equipment performance was associated with the number of years of using US equipment. It is necessary to maintain the best performance of the equipment phantom measurements for performance testing of US equipment
[en] Hydro-Quebec has been using CFD to analyze the performance of its existing turbines for many years. Most of those analyses are based on the measurement of a single runner blade. However, due to manufacturing techniques, in-situ modifications or repairs, there are often small differences between individual blades of the same runner. The impact of this non uniformity was not known thus far and was often assumed to be negligible given the size of the runner. This paper highlights the impact of such differences by presenting the CFD analysis of various blades measured on the same runner. Two different geometries are used for demonstration: the AxialT model propeller and a 50-MW Francis turbine. In both cases, about 50% of the blades could not be considered as representative of the whole turbine and using them could lead to wrong conclusions regarding the turbine performance.
[en] It is the application of nuclear instrumentation and research results, presented closed gas proportional counter of research, pre-trial preparation, the main performance test for detector test ideas. Preliminary preparation test now has been basically completed, ongoing pumping test inflated. (authors)
[en] This paper presents theoretical investigation of the energy-saving potentials of the eco-friendly R430A, R440A and R450A refrigerant mixtures in a domestic refrigerator. The results showed that R440A refrigerant mixture produced the highest coefficient of performance (COP). The COPs obtained for R430A and R440A were 5.57 and 10.70% higher, respectively, while the COP of R450A was 3.36% lower than that of R134a. All the three investigated alternative refrigerants exhibited low discharge pressure which is highly desirable in refrigeration system. R430A and R440A refrigerants produced higher refrigerating effect and volumetric cooling capacity (VCC) than R450A and R134a refrigerants. The average VCCs of R430A and R440A are 8.75 and 7.24%, respectively, higher than that of R134a, while the value of R450A is 4.77% lower than that of R134a. The results also showed that R430A and R440A are more energy saving than both R450A and R134a in the refrigeration system. The power per ton of refrigeration obtained for R430A and R440A is 5.48 and 10.46% lower, respectively, than the value of R134a, while the value for R450A is 4.62% higher than that of R134a. Generally, R430A and R440A performed better than both R450A and R134a in that they exhibited lower energy consumption per ton of refrigeration, lower discharge pressure, higher refrigerating effect, COP and volumetric cooling capacity than R450A and R134a. The overall best performance is obtained using R440A in the system.