ARE THE DEMANDS IN ENTERTAINMENT LIGHTING TOO HIGH FOR WHITE LIGHT EMITTING DIODES?

This paper reports the result of a survey on entertainment lighting distributed to 246 museums and 56 theatres in Sweden. The questions concerned the lighting technology used, experience from changing lighting systems, plans, problems, apprehensions and expectations. The replies showed that the transition to LED has been much faster in museums than in theaters and 35% of the theatres do not plan for a transition to LED. Reasons given are economy, light quality, and dimming functionality. Lighting professionals are generally sceptical in exchanging halogen lights. The artistic expression in lighting design goes beyond the specifications and what is promised in the data sheet. To facilitate a smoother transition to modern lighting technologies, the quality of the white light and proper function of the luminaires must be ensured and the communication between the manufacturers, retailers, lighting professionals and other artistic functions must be improved.

Colonoscopic Yield in Patients with Lower Gastrointestinal Bleeding – A Study of 309 Cases

Introduction: This retrospective study was done to see colonoscopic yields in patients presenting with lower gastrointestinal bleeding. Materials & Methods: Reports of patients undergoing colonoscopy due to bleeding per rectum were retrieved from endoscopy records. Patients’ particulars and colonoscopic findings were recorded in a data sheet. Analysis was done using SPSS 20 version. Results: A total of 309 patients (male 211 (68.3%) and female 98 (31.7) with mean age 40.3 years %)) were included in this study. According to colonoscopic yield, causes of LGIB were haemorrhoids 137 (44.33% ), rectal and colonic growth 58(18.77% ) rectal and colonic polyps 54 (17.47% ), anal fissure 38 (12.29% ), proctitis 18 (5.82%), colitis 18(5.82%), ileal ulcer and ileitis 34(11.0%). Colorectal growth was more common among patients age 26 to 60years. Among male rectal growth was slightly higher than female. Conclusion: Lower gastrointestinal bleeding is more common among males. Commonest cause of LGIB are internal haemorrhoids, rectal growth, rectal and colonic polyps and anal fissure. Colorectal neoplasm, proctitis, colitis and ileal inflammation and ulcers constitute small part. Medicine Today 2021 Vol.33(2): 120-122

Modeling and analysis of the characteristics of SiC MOSFET

Although the superior performance of SiC MOSFET devices has beenvalidated by many studies, it is necessary to overcome many technical bottlenecks to make SiC MOSFET gradually replace Si-based power devices into the mainstream. In view of the current situation where the performance of SiC MOSFETs in power conversion devices cannot be evaluated well at this stage, it is necessary to carry out fine modeling of SiC MOSFETs and establish accurate simulation models. In this paper, the powerful mathematical processing capability and rich modules of Matlab/Simulink are used to build a SiC MOSFET model, and then the product data sheet is compared with the fitted data. The results show that the switching simulation waveforms are in general agreement with the data sheet waveforms, and the error is less than 7%. Verifing the accuracy of the model and reducing the difficulty of modeling, it provides a new idea for establishing the circuit simulation model of SiC MOSFET in Matlab/Simulink.

Egy ismeretlen ismerős a 13–14. század fordulójáról: Haab

The present paper deals with the ecclesiastical career of a Hungarian prelate, Haab, who lived at the turn of the 13th‒14th centuries. The exact stages of his ecclesiastical career and its chronology are not yet clarifi ed, and there are similar diffi culties with his kinship. Haab’s case is a good example of how research can use detailed archontological research to reconstruct the career of a given person and create an accurate prosopographic data sheet.

Endpoint Use Efficiency Comparison for AC and DC Power Distribution in Commercial Buildings

Advances in power electronics and their use in Miscellaneous Electric Loads (MELs) in buildings have resulted in increased interest in using low-voltage direct current (DC) power distribution as a replacement for the standard alternating current (AC) power distribution in buildings. Both systems require an endpoint converter to convert the distribution system voltage to the MELs voltage requirements. This study focused on the efficiency of these endpoint converters by testing pairs of AC/DC and DC/DC power converters powering the same load profile. In contrast to prior studies, which estimated losses based on data sheet efficiency and rated loads, in this study, we used part load data derived from real-world time-series load measurements of MELs and experimentally characterized efficiency curves for all converters. The measurements performed for this study showed no systematic efficiency advantage for commercially available DC/DC endpoint converters relative to comparable, commercially available AC/DC endpoint converters. For the eight appliances analyzed with the pair of converters tested, in 50%, the weighted energy efficiency of the DC/DC converter was higher, while, for the other 50%, the AC/DC converter was. Additionally, the measurements indicated that the common assumption of using either data sheet efficiency values or efficiency at full load may result in substantial mis-estimates of the system efficiency.