A new method of switched reluctance wind power generation position sensorless based on DFNN by FEA was proposed, Through current and magnetic linkage to get the angle of SRG rotor position, the nonlinear mapping of cu...A new method of switched reluctance wind power generation position sensorless based on DFNN by FEA was proposed, Through current and magnetic linkage to get the angle of SRG rotor position, the nonlinear mapping of cur- rent-magnetic linkage-angle was built, By training these sample data from FEA, the angle of SRG rotor position was replaced by the output of DFNN to achieve SRG position sensorless. Simulation results show that the error between actual rotor position and estimate rotor position is small; SRG can commutate with great accuracy; and the output voltage of SRG wind power system under variable wind speed is essentially constant.展开更多
Objective To describe the pitfalls in positron emission tomography/computed tomography （PET/CT） imaging and classify them according to the principles of their generation. Methods We summarized retrospectively the ^...Objective To describe the pitfalls in positron emission tomography/computed tomography （PET/CT） imaging and classify them according to the principles of their generation. Methods We summarized retrospectively the ^18F-fluorodeoxyglucose （FDP） PET/CT imaging pitfalls through reviewing the PET/CT images of 872 patients. The pitfalls were divided into artifacts and infrequent physiological uptake, and the artifacts were further classified according to their causes. Meanwhile, we calculated the incidences of various pitfalls. Whether the PET/CT pitfalls influenced the diagnostic decision was analyzed. The appearances of pitfalls in PET were also described. Results Pitfalls could be found in PET/CT images of 684（78.4%） patients. Artifacts were found in 664 （76.15%） patients, and could be classified into self-factor artifacts and equipment-or technology-related artifacts. Among self-factor artifacts, respiratory motion （57.5%）, postprandial or hyperglycemia artifacts （2.41%）, and metal or high density matter artifacts （1.38%） were frequent. As for equipment-or tectmology-related factors, injection point outleakage or radiotracer contamination （13.88%） and truncation artifacts （1.83%） were most common ones. Infrequent physiological FDG uptakes, including fatty up-take, endometrial uptake, and bilateral breast feeding period uptake, were found in 20 （2.29%） patients. Among all pitfalls, the artifacts in 92 （13.4%） patients and infrequent physiological uptakes in 6 （0.88%） patients affected the diagnostic results. Artifact images in PET could be described as hot or cold area and the images of infrequent physiological uptake were always shown as hot area. Conclusions The incidence of pitfall in PET/CT imaging was high and the causes of pitfalls are various. Among all causes that artifacts generated, respiratory motion is the most common. Some pitfalls may disturb clinical physicians＇ decision, so it is important to recognize artifacts and physiological uptake, and distinguish them from pathological uptakes.展开更多
This paper finishes the classification of three-generator finite p-groups G such that Φ(G) Z(G).This paper is a part of classification of finite p-groups with a minimal non-abelian subgroup of index p, and partly sol...This paper finishes the classification of three-generator finite p-groups G such that Φ(G) Z(G).This paper is a part of classification of finite p-groups with a minimal non-abelian subgroup of index p, and partly solves a problem proposed by Berkovich(2008).展开更多
The exponential growth of utilizing synthetic organic molecules in optoelectronic applications poses strong demands for rational control over the excited states of the materials. The manipulation of excited states thr...The exponential growth of utilizing synthetic organic molecules in optoelectronic applications poses strong demands for rational control over the excited states of the materials. The manipulation of excited states through molecular design has led to the development of high-performance optoelectronic devices with tunable emission colors, high quantum efficiencies and efficient energy/charge transfer processes. Recently, a significant breakthrough in lifetime tuning of excited states has been made;the purely organic molecules were found to have ultralonglived excited state under ambient conditions with luminescence lifetimes up to 1.35 s, which are several orders of magnitude longer than those of conventional organic fluorophores. Given the conceptual advance in understanding the fundamental behavior of excited state tuning in organic luminescent materials, the investigations of organic ultralong room-temperature phosphorescence(OURTP) should provide new directions for researches and have profound impacts on many different disciplines. Here, we summarized the recent understandings on the excited state tuning, the reported OURTP molecules and their design considerations,the spectacular photophysical performance, and the amazing optoelectronic applications of the newly emerged organic optoelectronic materials that free of heavy metals.展开更多
基金Supported by the National Natural Science Foundation of China （50977080） the Science ＆ Technology Department Project of Hunan Province （2010F J3116） the Education Department Project of Hunan Province （ 10A 114）
文摘A new method of switched reluctance wind power generation position sensorless based on DFNN by FEA was proposed, Through current and magnetic linkage to get the angle of SRG rotor position, the nonlinear mapping of cur- rent-magnetic linkage-angle was built, By training these sample data from FEA, the angle of SRG rotor position was replaced by the output of DFNN to achieve SRG position sensorless. Simulation results show that the error between actual rotor position and estimate rotor position is small; SRG can commutate with great accuracy; and the output voltage of SRG wind power system under variable wind speed is essentially constant.
文摘Objective To describe the pitfalls in positron emission tomography/computed tomography （PET/CT） imaging and classify them according to the principles of their generation. Methods We summarized retrospectively the ^18F-fluorodeoxyglucose （FDP） PET/CT imaging pitfalls through reviewing the PET/CT images of 872 patients. The pitfalls were divided into artifacts and infrequent physiological uptake, and the artifacts were further classified according to their causes. Meanwhile, we calculated the incidences of various pitfalls. Whether the PET/CT pitfalls influenced the diagnostic decision was analyzed. The appearances of pitfalls in PET were also described. Results Pitfalls could be found in PET/CT images of 684（78.4%） patients. Artifacts were found in 664 （76.15%） patients, and could be classified into self-factor artifacts and equipment-or technology-related artifacts. Among self-factor artifacts, respiratory motion （57.5%）, postprandial or hyperglycemia artifacts （2.41%）, and metal or high density matter artifacts （1.38%） were frequent. As for equipment-or tectmology-related factors, injection point outleakage or radiotracer contamination （13.88%） and truncation artifacts （1.83%） were most common ones. Infrequent physiological FDG uptakes, including fatty up-take, endometrial uptake, and bilateral breast feeding period uptake, were found in 20 （2.29%） patients. Among all pitfalls, the artifacts in 92 （13.4%） patients and infrequent physiological uptakes in 6 （0.88%） patients affected the diagnostic results. Artifact images in PET could be described as hot or cold area and the images of infrequent physiological uptake were always shown as hot area. Conclusions The incidence of pitfall in PET/CT imaging was high and the causes of pitfalls are various. Among all causes that artifacts generated, respiratory motion is the most common. Some pitfalls may disturb clinical physicians＇ decision, so it is important to recognize artifacts and physiological uptake, and distinguish them from pathological uptakes.
基金supported by National Natural Science Foundation of China(Grant No.11371232)Natural Science Foundation of Shanxi Province(Grant Nos.2012011001-3 and 2013011001-1)
文摘This paper finishes the classification of three-generator finite p-groups G such that Φ(G) Z(G).This paper is a part of classification of finite p-groups with a minimal non-abelian subgroup of index p, and partly solves a problem proposed by Berkovich(2008).
基金supported in part by the National Natural Science Foundation of China(21274065,21304049,61204048 and 51173081)The Ministry of Education of China(IRT1148)+1 种基金a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(YX03001)the Qing Lan Project of Jiangsu Province
文摘The exponential growth of utilizing synthetic organic molecules in optoelectronic applications poses strong demands for rational control over the excited states of the materials. The manipulation of excited states through molecular design has led to the development of high-performance optoelectronic devices with tunable emission colors, high quantum efficiencies and efficient energy/charge transfer processes. Recently, a significant breakthrough in lifetime tuning of excited states has been made;the purely organic molecules were found to have ultralonglived excited state under ambient conditions with luminescence lifetimes up to 1.35 s, which are several orders of magnitude longer than those of conventional organic fluorophores. Given the conceptual advance in understanding the fundamental behavior of excited state tuning in organic luminescent materials, the investigations of organic ultralong room-temperature phosphorescence(OURTP) should provide new directions for researches and have profound impacts on many different disciplines. Here, we summarized the recent understandings on the excited state tuning, the reported OURTP molecules and their design considerations,the spectacular photophysical performance, and the amazing optoelectronic applications of the newly emerged organic optoelectronic materials that free of heavy metals.
