Enhanced Heat Dissipation Performance of Automotive LED Lamps Using Graphene Coatings

Graphene heat-dissipating coating (GNHC) of 0.6 wt % GN concentration is utilized to promote the cooling performance of automotive light-emitting diode (LED) lamps. Three cases are studied as follows: Case 0 is the original automotive LED lamp as the baseline. Case 1 is to apply GNHC to reduce the thermal resistance of the junction surfaces between the components of automotive LED lamps. The aluminum fin radiator of Case 1 is further coated with GNHC on the surface that becomes Case 2. The spectrum, illuminance, power consumption, and surface temperature are measured at different ambient temperatures (Ta) to fully evaluate the feasibility of applying GNHC to improve cooling performance and the impacts on the related characteristics of automotive LED lamps. The results show that the maximum illuminance efficacy of Case 1 and Case 2 with high beam, irradiation angle of 0 degrees, and Ta of 80 °C is 11.03% and 8.70% higher than that of Case 0, respectively. The minimum temperature difference of heat dissipation path of Case 1 and Case 2 with high beam, irradiation angle of 90 degrees, and Ta of 80 °C is 6.41% and 5.33% lower than that of Case 0, respectively, indicating GNHC as a promising coating material for improving the cooling performance of automotive LED lamps.

The Pitfalls and Strategies of Endoscopic Localization in Laparoscopic Colectomy: A Case Report

Background: laparoscopic segmental colectomy is suitable for removing difficult polyps that are large, broad-based, or located in tortuous bowel segments. As we know, accurate segmental resection depends on precise localization. So far, intraoperative labeling of lesions by colonoscopy is increasingly performed for achieving appropriate resection margins, but a certain deviation is also found. There is no unified and standard endoscopic polyp localization method at present.Case presentation: A 63-year-old woman was admitted because she was diagnosed as a large and broad-based colonic polyp which was unsuitable for colonoscopic polypectomy. During endoscopy-assisted laparoscopic segmental colectomy, the irradiation angle of colonoscopy light on the polyp head was responsible for the localization errors. We proposed three-step measures of correct endoscopic polyp localization to ensure the accurate resection in laparoscopic segmental colectomy.Conclusions: Three-step measures of correct endoscopic polyp localization ensured the successful resection of colonic polyps in laparoscopic colectomy. Their advantages include simplicity, practicality and reliable localization.

Experimental and Numerical Study on the Heat Transfer Characteristics of a Newly-Developed Solar Active Thermal Insulation System

A newly-developed solar active thermal insulation system (SATIS) is introduced with the main objective to accomplish a highly-dependent total solar transmittance on the irradiation angle. SATIS is also designed to obtain the maximum transmittance at a prescribed design irradiation angle and to reduce it remarkably at higher irradiation angles. A purely mineral thermal insulation plaster with micro hollow glass spheres is applied to manufacture the investigated SATIS prototype. Light-conducting elements (LCEs) have been introduced into SATIS and suitable closing elements have been applied. The SATIS prototype has been investigated both experimentally and numerically. It turned out that the contributions of conduction, radiation and convection to the effective thermal conductivity of SATIS, without the closing elements (49 mWmK), amount to 86.2%, 13.2% and 0.6%, respectively. The angle-dependent short-wave radiation exchange within the LCE has been investigated via ray tracing. At the incidence angle of 19% (design angle), 27% of the radiation within the LCE is absorbed by the absorber plate, resulting in measured and computed total solar energy transmittances of 11.2%/11.7%, respectively. For a typical summer irradiation angle of 60%, 98% of the incident radiation is absorbed by the surfaces at the entrance of the LCE. The corresponding total solar energy transmittance amounts to 2.9%.

A novel setup to examine sputtering characteristics of mineral samples

<p>The surface of bodies without a thick atmosphere in outer space is exposed to the harsh space environment [1]. Space weathering alters its properties and leads to the formation of a tenuous exosphere. This elevated density of particles is coupled to the surface and therefore carries information about the latter. The BepiColombo mission aims to probe the composition of Mercury’s exosphere for the purpose of extracting this information [2]. However, this task requires precise models of exosphere formation [3]. Sputtering by solar wind ions is expected to be one of the main drivers for exosphere formation and models are therefore sensitive to sputtering inputs. So far, mainly simulation data are used, as experimental sputtering data for relevant materials are rare. Furthermore, available measurements have been typically performed with amorphous thin films due to use of the Quartz Crystal Microbalance (QCM) technique for sputtering measurements [4, 5]. Such a QCM is very sensitive to mass changes with resolutions in the sub mono-layer regime and is therefore an ideal tool for quantitative measurements of sputtering yields [6].</p><p>We introduce a new method for determining sputtering yields of more realistic samples, which allows to overcome the limitations of thin films while making use of the high sensitivity of QCMs. For this purpose, pellets pressed from minerals that are relevant for Mercury are used. The primary sample holder is placed on a xyzφ -manipulator, which enables switching between different samples and varying the irradiation angle α. A secondary quartz (C-QCM) is placed on an independently rotatable manipulator. This setup allows probing the angular distribution of sputtered particles by determining the mass change ∆m ion<sup>−1 </sup>in dependence on the angle α<sub>C</sub> between the sample and the C-QCM, which can lead to further improvement of exosphere models. Furthermore, mass changes of the irradiated sample due to ion implantation [7], can be untangled as only deposition of ejected particles contributes to the C-QCM signal. The use of pressed pellets enables a variation in sample parameters not accessible with thin films like crystal structure, surface roughness and porosity. Nonetheless, a QCM coated with the same material is installed on the primary sample holder in addition to the pellet for calibration.<br>First results with the Ca-pyroxenoid wollastonite (CaSiO3) and 2 keV Ar<sup>+</sup> ions are very promising. They indicate no difference in sputtering of the amorphous thin film and the pressed wollastonite pellet for Ar<sup>+</sup> irradiations. In a next step, solar wind ions will be used, which will improve the understanding of sputtering of realistic samples by solar wind ions. </p><p><strong>References</strong></p><p>[1] Hapke B.: J. Geophys. Res. Planet., 106, 10039, 2001.<br>[2] Milillo A., et al.: Planet. Space Sci., 58, 40, 2010.<br>[3] Wurz P., et al.: Planet. Space Sci., 58, 1599, 2010.<br>[4] Szabo P. S., et al.: Astrophys. J., 891, 100, 2020.<br>[5] Hijazi H., et al.: J. Geophys. Res. Planets, 122, 1597, 2017.<br>[6] Hayderer G., et al.: Rev. Sci. Instrum., 70, 3696, 1999.<br>[7] Biber H., et al.: Nucl. Instrum. Methods Phys. Res. B, 480, 10, 2020.</p>

DE-ORBIT BEHAVIORS OF NANOSECOND LASER DRIVING SMALL SCALE SPACE DEBRIS IN LOW EARTH ORBIT

The aim of this article was to address the de-orbit behaviors of space-based laser driving small scale space debris in low earth orbit (LEO) based on different orbit and laser parameters in coplanar/non-coplanar conditions. The de-orbit model of space-based laser irradiating small scale space debris was established, the de-orbit rules of irradiation angle and irradiation distance with action time in different orbital inclination and right ascension of the ascending node (RAAN) were investigated by numerical simulations, and the change rules of the perigee altitude with the number of laser pulses were discussed in different orbital inclination and RAAN. As a result, the clearance window of removing small scale space debris was described in detail. These results of numerical simulations will provide theoretical guide for designing clear schemes and selecting efficient parameters.

A Simple Designed Lens for Human Centric Lighting Using LEDs

Light is generally important for human beings. Visible light supports vision and can modify circadian rhythm, and together with invisible light at longer or shorter wavelength can also make either a direct or indirect impact on human biological and mental health. For medical applications, several studies have shown success in using light to fasten the skin regeneration in burns and to cure diseases such as newborn jaundice. In daily life, an appropriate amount and time exposure to certain types of light can result in rising of alertness and mood improvement, which leads to noticeable growth in one’s productivity. Therefore, human centric lighting can modify lighting factors to make the best of the natural characteristics of light. The seek an ideal indoor lighting system is widely carried out not only by scientists but also by architects. A qualified luminaire is considered by many factors, including luminous productivity, visual comfort and expenses; meanwhile, the idealization of illuminance is also constructed in many ways, such as widening the lamp’s surface area, changing of luminaire’s positions and applying different methods to illuminate a surface. Approaching these problems, our idea is to study the uplighting method and freeform optics using low-cost acrylic lenses. By changing lens shape and optimizing the factors which affect the illuminance such as the irradiation angle and the distance between the luminaire and the reflection surfaces, we find the most effective lens and its peaks due to each factors using the ray-tracing simulation to obtain results concerning high uniformity of illumination.