A herringbone water-sediment separation structure(hereinafter referred to as "herringbone structure") has been shown to be effective in separating coarse inorganic debris; however, less is known regarding th...A herringbone water-sediment separation structure(hereinafter referred to as "herringbone structure") has been shown to be effective in separating coarse inorganic debris; however, less is known regarding the large wood(LW) filtration effect in this structure. This paper presents preliminary research on the wood filtration effect of the herringbone structure based on physical model tests.The results show that the herringbone structure exhibited effective performance in large wood size segregation, with a 100% component filtration rate for LW that diameter(D) larger than ribbed beam opening width(a). The total filtration rate also exceeded 80% when the Fraud number(Fr) is larger than 2.64 and increased with the increase of Fr. After exceeding Frmax, total filtration rate would be decreased due to overflow. Beside flow condition,structure parameters influence significantly on LW filtration rate. We attempt to explain the filtration process via particle contact trajectory and particle movement trajectory. The inclined angle of ribbed beam(γ) contributed the most variation to the filtration rate via influencing the coincidence with particle contact trajectory and particle movement trajectory. The high sensitivity coefficient of ribbed beam(θ) under relatively low Fr conditions implies remarkable influences on LW filtration effects by causing clogging problem. The ribbed beam opening width(a) together with LW diameter(D) influenced the size segregation performance.展开更多
Objective To compare contrast-enhanced magnetic resonance imaging （ceMRI） with nuclear metabolic imaging for the assessment of myocardial viability in patients with chronic ischemic heart disease. Methods Twenty pa...Objective To compare contrast-enhanced magnetic resonance imaging （ceMRI） with nuclear metabolic imaging for the assessment of myocardial viability in patients with chronic ischemic heart disease. Methods Twenty patients with suspected chronic ischemic heart disease underwent ceMRI and technetium-99m sestamibi single-photon emission computed tomography （SPECT）. Patients with positive SPECT results also underwent 18 F-fluorodeoxyglucose （FDG） SPECT. In a 17-segment model, the segmental extent of hyperenhancement （SEH） by ceMRI was compared with segmental FDG and sestamibi uptake by SPECT. Correlation between the extent of hyperenhancement by ceMRI and left ventricular function was analyzed. Seven patients got negative results both in ceMRI and technetium-99m sestamibi SPECT. The rest 13 patients with positive results then underwent ^18F-FDG SPECT. In 221 segments of 13 patients, SEH was （2. 1±8.2）%, （25.0±13.7 ）%, and （57. 7±23.6 ）% in segments with normal metabolism/perfusion, metabolism/perfusion mismatch, and matched defects, respectively, and there were significant differences between either two of them （ all P 〈 0.05）. By receiver operating characteristic curve analysis, the area under the curve was 0. 95 for the differentiation between viable and non-viable segments. At the cutoff value of 34%, SEH optimally differentiated viable from non-viable segments defined by SPECT. Using this threshold, the sensitivity and specificity of ceMRI to detect non-viable myocardium as defined by SPECT were 92% and 93%, respectively. Hyperenhancement size by ceMRI was correlated negatively with the left ventricular ejection fraction （ r = - 0.90, P 〈 0.01 ） and positively with left ventricular volumes （ r = 0. 62 for end-diastolic volume, r = 0.75 for end-systolic volume, both P 〈 0.05 ）. Conclusion CeMRI allows assessment of myocardial viability with a high accuracy in patients with chronic ischemic heart disease.展开更多
基金funded by the National Science and Technology Support Program(2011BAK12B00)the International Cooperation Project of the Department of Science and Technology of Sichuan Province(Grant No.2009HH0005).
文摘A herringbone water-sediment separation structure(hereinafter referred to as "herringbone structure") has been shown to be effective in separating coarse inorganic debris; however, less is known regarding the large wood(LW) filtration effect in this structure. This paper presents preliminary research on the wood filtration effect of the herringbone structure based on physical model tests.The results show that the herringbone structure exhibited effective performance in large wood size segregation, with a 100% component filtration rate for LW that diameter(D) larger than ribbed beam opening width(a). The total filtration rate also exceeded 80% when the Fraud number(Fr) is larger than 2.64 and increased with the increase of Fr. After exceeding Frmax, total filtration rate would be decreased due to overflow. Beside flow condition,structure parameters influence significantly on LW filtration rate. We attempt to explain the filtration process via particle contact trajectory and particle movement trajectory. The inclined angle of ribbed beam(γ) contributed the most variation to the filtration rate via influencing the coincidence with particle contact trajectory and particle movement trajectory. The high sensitivity coefficient of ribbed beam(θ) under relatively low Fr conditions implies remarkable influences on LW filtration effects by causing clogging problem. The ribbed beam opening width(a) together with LW diameter(D) influenced the size segregation performance.
文摘Objective To compare contrast-enhanced magnetic resonance imaging （ceMRI） with nuclear metabolic imaging for the assessment of myocardial viability in patients with chronic ischemic heart disease. Methods Twenty patients with suspected chronic ischemic heart disease underwent ceMRI and technetium-99m sestamibi single-photon emission computed tomography （SPECT）. Patients with positive SPECT results also underwent 18 F-fluorodeoxyglucose （FDG） SPECT. In a 17-segment model, the segmental extent of hyperenhancement （SEH） by ceMRI was compared with segmental FDG and sestamibi uptake by SPECT. Correlation between the extent of hyperenhancement by ceMRI and left ventricular function was analyzed. Seven patients got negative results both in ceMRI and technetium-99m sestamibi SPECT. The rest 13 patients with positive results then underwent ^18F-FDG SPECT. In 221 segments of 13 patients, SEH was （2. 1±8.2）%, （25.0±13.7 ）%, and （57. 7±23.6 ）% in segments with normal metabolism/perfusion, metabolism/perfusion mismatch, and matched defects, respectively, and there were significant differences between either two of them （ all P 〈 0.05）. By receiver operating characteristic curve analysis, the area under the curve was 0. 95 for the differentiation between viable and non-viable segments. At the cutoff value of 34%, SEH optimally differentiated viable from non-viable segments defined by SPECT. Using this threshold, the sensitivity and specificity of ceMRI to detect non-viable myocardium as defined by SPECT were 92% and 93%, respectively. Hyperenhancement size by ceMRI was correlated negatively with the left ventricular ejection fraction （ r = - 0.90, P 〈 0.01 ） and positively with left ventricular volumes （ r = 0. 62 for end-diastolic volume, r = 0.75 for end-systolic volume, both P 〈 0.05 ）. Conclusion CeMRI allows assessment of myocardial viability with a high accuracy in patients with chronic ischemic heart disease.
