17 research outputs found
Создание опытного образца геохода. Временной фактор изготовления компонентов и их сборки в конечное изделие
Изложен опыт реализации проекта №02.G25.31.0076 в рамках открытого конкурса Министерства образования и науки РФ и Постановления Правительства РФ №218 от 09.04.2010 г. Дано описание временных рамок реализации проекта, в частности, работы над созданием опытного образца щитового проходческого агрегата - геохода, диаметром 3,2 м. В настоящее время проект находится в стадии завершения. Главная идея статьи - поделиться опытом создания новой техники и показать, сколько времени затрачивается на решение тех или иных производственных процессов по созданию опытных образцов горных машин на примере геохода. Данная статья будет полезна организациям, планирующим участие в реализации проектов по созданию высокотехнологичного производства, и может являться ориентиром для составления Плана-графика реализации подобных проектов. Автор статьи лично принимал участие в реализации данного проекта и принимал решения по планированию и организации работ.The experience of the project №02.G25.31.0076 is presented. The project was operated in the framework of the open competition of the Ministry of education and science of the Russian Federation and the RF Government Decree №218 from 09.04.2010. Description of the time frame of the project implementation, particularly the activities of the TBM prototype creation - geokhod, with a diameter of 3.2 m. is presented. Currently, the project is closer to complete. The main idea of the article is to share the experience of creating new technology and show how much time is spent on the decision of production processes to create prototypes of mining machines on the example of a geokhod. This article will be useful for organizations planning to participate in the implementation of projects to create high-tech production, and can be a guide for drawing up a Plan-schedule of such projects. The author of this article personally participated in the implementation of this project and made decisions on planning and organization of activities
Assessment of Global Right Ventricular Function on 64-MDCT compared with MRI
Cédric Plumhans1, Georg Mühlenbruch1, Annuar Rapaee2, Kui-Hian Sim2, Tobias
Seyfarth3, Rolf W. Günther1 and Andreas H. Mahnken
Comparison of (semi-)automatic and manually adjusted measurements of left ventricular function in dual source computed tomography using three different software tools
To assess the accuracy of (semi-)automatic measurements of left ventricular (LV) functional parameters in cardiac dual-source computed tomography (DSCT) compared to manually adjusted measurements in three different workstations. Forty patients, who underwent cardiac DSCT, were included (31 men, mean age 58 ± 14 years). Multiphase reconstructions were made with ten series at every 10% of the RR-interval. LV function analysis was performed on three different, commercially available workstations. On all three workstations, end-systolic volume (ESV), end-diastolic volume (EDV), LV ejection fraction (LVEF) and myocardial mass (MM) were calculated as automatically as possible. With the same DSCT datasets, LV functional parameters were also calculated with as many manual adjustments as needed for accurate assessment for all three software tools. For both semi-automatic as well as manual methods, time needed for evaluation was recorded. Paired t-tests were employed to calculate differences in LV functional parameters. Repeated measurements were performed to determine intra-observer and inter-observer variability. (Semi-)automatic measurements revealed a good correlation with manually adjusted measurements for Vitrea (LVEF r = 0.93, EDV r = 0.94, ESV r = 0.98 and MM r = 0.94) and Aquarius (LVEF r = 0.96, EDV r = 0.94, ESV r = 0.98 and MM r = 0.96). Also, good correlation was obtained for Circulation, except for LVEF (LVEF r = 0.45, EDV r = 0.93, ESV r = 0.92 and MM r = 0.86). However, statistically significant differences were found between (semi-)automatically and manually adjusted measurements for LVEF (P < 0.05) and ESV (P < 0.001) in Vitrea, all LV functional parameters in Circulation (P < 0.001) and EDV, ESV and MM (<0.001) in Aquarius Workstation. (Semi-)automatic measurement of LV functional parameters is feasible, but significant differences were found for at least two different functional parameters in all three workstations. Therefore, expert manual correction is recommended at all times
Left and right ventricle assessment with Cardiac CT: validation study vs. Cardiac MR
Objectives To compare Magnetic Resonance (MR) and Computed Tomography (CT) for the assessment of left (LV) and right (RV) ventricular functional parameters. Methods Seventy nine patients underwent both Cardiac CT and Cardiac MR. Images were acquired using short axis (SAX) reconstructions for CT and 2D cine b-SSFP (balanced- steady state free precession) SAX sequence for MR, and evaluated using dedicated software. Results CT and MR images showed good agreement: LV EF (Ejection Fraction) (52±14% for CT vs. 52±14% for MR; r0 0.73; p>0.05); RV EF (47±12% for CT vs. 47±12% for MR; r00.74; p>0.05); LV EDV (End Diastolic Volume) (74± 21 ml/m 2 for CT vs. 76±25 ml/m 2 for MR; r00.59; p>0.05); RV EDV (84±25 ml/m 2 for CT vs. 80±23 ml/m 2 for MR; r0 0.58; p>0.05); LV ESV (End Systolic Volume)(37±19 ml/m 2 for CT vs. 38±23 ml/m 2 for MR; r00.76; p>0.05); RV ESV (46±21 ml/m 2 for CT vs. 43±18 ml/m 2 for MR; r00.70; p>0.05). Intra- and inter-observer variability were good, and the performance of CT was maintained for different EF subgroups. Conclusions Cardiac CT provides accurate and reproducible LVand RV volume parameters compared with MR, and can be considered as a reliable alternative for patients who are not suitable to undergo MR. Key Points • Cardiac-CT is able to provide Left and Right Ventricular function. • Cardiac-CT is accurate as MR for LV and RV volume assessment. • Cardiac-CT can provide accurate evaluation of coronary arteries and LV and RV function
Hypoxia and myocardial remodeling in human cardiac allografts: a time-course study.
BACKGROUND: Cardiac allografts are known to develop myocardial fibrosis, which may be a cause of progressive cardiac dysfunction. Apart from the renin-angiotensin and transforming growth factor-beta system, hypoxia has been proposed as an important player in the pathogenesis of fibrosis, but its significance remains unclear. This study examines the degree of myocardial fibrosis, cellular remodeling and hypoxic signaling over a time-course of 10 years after human cardiac allograft transplantation. METHODS: Serial right ventricular biopsies of 57 patients were collected in 6-month intervals after cardiac transplant surgery for a total of 10 years to allow a retrospective longitudinal analysis. Over this period, tissue remodeling, including interstitial fibrosis and cellular changes, were determined morphometrically. Immunohistochemistry (IHC) was used to analyze expression of the following hypoxia-related proteins: hypoxia-induced factor 1-alpha (HIF1alpha); the oxygen sensor prolyl hydroxylase 3 (PHD3); and vascular endothelial growth factor (VEGF). RESULTS: Fibrosis increased significantly from 12.6 +/- 6.5% at the point of transplantation throughout follow-up to 28.8 +/- 7.7% at 10 years. The DNA content and number of nuclei changed over the period of follow-up, displaying signs of cellular hypertrophy and a loss of myocytes. Whereas HIF1alpha expression revealed a U-shaped pattern with both early and late elevation during fibrogenesis, PHD3 and VEGF expression patterns showed a gradual increase with PHD3 decreasing again in later fibrogenesis. CONCLUSIONS: In cardiac allografts, extensive and progressive tissue remodeling is present. Hypoxia may play a role in this process by up-regulating HIF1alpha and leading to differential regulation of pro-angiogenic signals