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For future space transportation and planetary exploration mission power applications, NASA Glenn Research Center (GRC) is currently developing a small-scale nuclear fission system (i.e. Kilopower system), which has an operable range of 1 to 10 kWe and a design life of 8 to 15 years. The thermal management system of Kilopower system involves two types of heat pipes: high temperature alkali metal heat pipes that are used to transport thermal energy from the nuclear reactor to the Stirling convertors hot end and titanium water heat pipes that are used to remove the waste heat from the convertors cold end and transport it to the radiators for ultimate rejection. This paper presents the development of the titanium water heat pipes, which are featured with a special wick structure design: it has bi-porous screened evaporator and screen-groove hybrid wick in the adiabatic and condenser sections. This will allow the heat pipe to (1) operate in space with zero gravity (2) operate on planetary surface with gravity-aided orientation (3) be tested on ground with slight adverse gravity orientation and (4) to startup smoothly after being frozen. Under a research and development program, several freeze/thaw tolerant heat pipes were designed, fabricated and experimentally validated. Later, various heat pipe radiators were developed and tested in a thermal vacuum chamber (TVC). Test results successfully demonstrated that the titanium heat pipes with radiator attached are able to transfer the required power at the working temperature of 400 K under space-like testing conditions with a thermal resistance of 0.019 °C/W while the total heat pipe radiator weight is less than 0.73 kg.

Bottom ash (BA) from incineration has been reused as a construction material for years. However, thermal treatments, which incur extra cost and higher energy demand, are essential to reduce/stabilize the polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in BA, which can be released from BA during the next startup and cause peak emissions. In this study, the bottom ash from a laboratory waste incinerator (LWI) was collected and quenched at various temperatures during three shutdown operations to determine the results of the gradual cooling process. The PCDD/F content in the BA was quantified using gas chromatography-mass spectrometry. The PCDD/Fs in BA was significantly lower (0.0239 ng WHO-TEQ g−1) after being quenched at >400 °C, which was only 1/300 of that in the sample gradually cooled to 0.97. In other words, careful operation of the cooling process is an important PCDD/F inhibition strategy and effectively reduces the subsequent startup emissions. Interestingly, the extremely low PCDD/F levels in the BA after quenching were found to further save the cost of thermal treatment, reduce electricity use by 500 MWh, and lower fuel consumption by 27 kL of diesel, as well as reducing annual CO2e emissions by 351 tons in an LWI. This finding could be further applied to simultaneously control PCDD/F emissions, save post-treatment costs, and reduce the secondary pollutants in other incinerators.

This work presents a method for obtaining a color-converted red light source through a combination of a blue GaN light-emitting diode and a red fluorescent color conversion film of a perovskite CsPbI3/TOPO composite. High-quality CsPbI3 quantum dots (QDs) were prepared using the hot-injection method. The colloidal QD solutions were mixed with different ratios of trioctylphosphine oxide (TOPO) to form nanowires. The color conversion films prepared by the mixed ultraviolet resin and colloidal solutions were coated on blue LEDs. The optical and electrical properties of the devices were measured and analyzed at an injection current of 50 mA; it was observed that the strongest red light intensity was 93.1 cd/m2 and the external quantum efficiency was 5.7% at a wavelength of approximately 708 nm when CsPbI3/TOPO was 1:0.35.

In this study, the atmospheric PM2.5, increases/decreases of the PM2.5, the PM2.5/PM10 ratio, total PCDD/Fs-TEQ concentrations, PM2.5-bound total PCDD/Fs-TEQ content, and PCDD/F gas-particle partition in Taiwan were investigated for the period 2013 to 2017. In Taiwan, the annual average PM2.5 concentrations were found to be 28.9, 24.1, 21.4, 20.2, and 19.9 µg m–3 in 2013, 2014, 2015, 2016, and 2017, respectively, which indicated that the annual variations in PM2.5 levels were decreasing during the study period. The average increases (+)/decreases (–) of PM2.5 concentrations were –16.7%, –11.1%, –5.75%, and –1.73% from 2013 to 2014, from 2014 to 2015, from 2015 to 2016, and from 2016 to 2017, respectively. Based to the relationship between PM10 values and total PCDD/F concentrations obtained from previous studies, we estimated that in 2017, the annual average total PCDD/Fs-TEQ concentrations ranged between 0.0148 (Lienchiang County) and 0.0573 pg WHO2005-TEQ m–3 (Keelung City), and averaged 0.0296 pg WHO2005-TEQ m–3, while the PM2.5-bound total PCDD/Fs-TEQ content ranged from 0.302 (Kaohsiung City) to 0.911 ng WHO2005-TEQ g–1 (Keelung City), at an average of 0.572 ng WHO2005-TEQ g–1. These values are suggested to be validated in the future study because the sources and formations of PM10 and PM2.5 in different areas were diverse, and may be not closely related to combustion sources. The seasonal variations in the gas fraction of total PCDD/Fs-WHO2005-TEQ concentrations were 68.6%, 86.6%, 82.3%, and 52.3% in the spring, summer, autumn, and winter, respectively. Due to the fact that Taiwan is located mostly in the sub-tropical zone, which had annual average temperatures between 23.0 and 24.4°C, averaging 23.8°C during the study period, the majority of PCDD/Fs-TEQ were dominant in the gas phase.

Inorganic hole transporting layer (HTL) plays the most important role to fabrication of low cost and stable in perovskite solar cells. Herein, we present low cost highly transparent and ultra-thin sputtered Cu2ZnSnSe4 (CZTSe) combined with solution-processed NiOx films as a double-layered inorganic HTL applied in inverted CH3NH3PbI3 perovskite solar cells, which is beneficial to enhance hole extraction and suppress electron transport. Sputtered CZTSe films have high transmittance (> 85%), high hole mobility (15.1 cm2 v−1 s−1), low resistivity (0.33 Ω-cm), earth-abundant elemental constituents, and non-toxic properties, which is one of the promising p-type inorganic hole-transporting material. An obvious enhancement of open-circuit voltage (Voc), short-circuit current density (Jsc), fill factor (FF), and power conversion efficiency (PCE) of a 600 °C-annealed-CZTSe/NiOx double-layered HTL based inverted perovskite solar cell was observed, and final Voc, Jsc, FF, and PCE of 1.03 V, 17.9 mA cm−2, 73%, and 13.46% were achieved, respectively. Importantly, the ultra-thin CZTSe/NiOx double-layer HTL makes the perovskite solar cell exhibit improved stability, of which this device remains 73% of the initial PCE value after 350 h′ storage in the nitrogen-filled glove box.

Recently, deep learning is one of the popular ways of object detection, and the most important thing in object detection is the dataset, which is used in the training process. However, when we look over the dataset, we can find that most of accessible dataset is taken during the good weather (e.g., sunny day) with the simple environmen, most of the testing pictures and videos are also taken in the same environment. When we turn to test the model that is trained by bright and simple dataset during the bad weather (e.g., rainy day, cloudy day stormy, foggy day) or in the dim place (e.g., tunnel, night, dusk, under the object's shade), we will get a bad performance. To solve this problem, we use Photoshop to modify the original dataset, try to make the dataset more versatile and larger in number of images according to the real environment. Our experiments show that we improve the accuracy from 98.6% to 99.3% for the daytime testing dataset. And for the nighttime testing dataset, we improve the accuracy from 22% to 50%.

This paper presents a new type of solar cellwith enhanced optical-current characteristics using an ultra-thin CuIn1&minus, xGaxSe2 hole-transporting material (HTM) layer (&lt, 400 nm). The HTM layer was between a bi-layer Mo metal-electrode and a CH3NH3PbI3 (MAPbI3) perovskite active absorbing material. It promoted carrier transportand led to an improved device with good ohmic-contacts. The solar cell was prepared as a bi-layer Mo/CuIn1&minus, xGaxSe2/perovskite/C60/Ag multilayer of nano-structures on an FTO (fluorine-doped tin oxide) glass substrate. The ultra-thin CuIn1&minus, xGaxSe2 HTM layers were annealed at various temperatures of 400, 500, and 600 &deg, C. Scanning electron microscopy studies revealed that the nano-crystal grain size of CuIn1&minus, xGaxSe2 increased with the annealing temperature. The solar cell results show an improved optical power conversion efficiency at ~14.2%. The application of the CuIn1&minus, xGaxSe2 layer with the perovskite absorbing material could be used for designing solar cells with a reduced HTM thickness. The CuIn1&minus, xGaxSe2 HTM has been evidenced to maintain a properopen circuit voltage, short-circuit current density and photovoltaic stability.

A variable conductance thermosyphon is a unique type of heat pipe that responds passively to changes in thermal environment because of the presence of non-condensable gas (NCG). In this study, we develop a computational fluid dynamics (CFD) model to predict the behavior of a cylindrical-shaped variable conductance thermosyphon in the vertical orientation for a range of evaporator-side operating temperatures between 66.70 °C and 87.32 °C. Experiments are performed on a variable conductance thermosyphon that is made of a 262 mm long stainless steel tube with an outer diameter of 9.5 mm and a wall thickness of 0.92 mm. The working fluid is methanol and the NCG is argon. The model is able to predict the fluid flow and heat transfer in the fluid domain and the conjugate heat transfer to the solid wall domain. Experimental thermocouple data for both forced convection and natural convection test cases show temperature remaining almost uniform in the adiabatic section and dropping rapidly across the vapor/NCG interface between the vapor and NCG. This behavior of wall temperature change was also captured accurately by the CFD model, evidenced by MAEs of 3.09% and 3.52% for forced and natural convection test cases, respectively.

In this study, solutions containing inorganic–organic FAPbBr3−xIx perovskite quantum dots were prepared at room temperature by jointly employing the ligand-assisted reprecipitation combined with ultrasonic methods. Subsequently, FAPbBr2I, FAPbBr1.5I1.5, and FAPbBrI2 were obtained by adjusting the relative proportions of halogen compounds × = (1, 1.5, 2). Through purification, quantum dot particles were separated while oleic acid was simultaneously removed from the quantum dot solutions. Next, a chlorobenzene dispersion was applied to acquire quantum dot solutions. Finally, through spin coating, FAPbBr3−xIx perovskite quantum dots red light-emitting diodes with double confinement layer structure were produced.

We demonstrate a method to enhance the power conversion efficiency (PCE) of MAPbI3 perovskite solar cells through localized surface plasmon (LSP) coupling with gold nanoparticles:CsPbBr3 hybrid perovskite quantum dots (AuNPs:QD-CsPbBr3). The plasmonic AuNPs:QD-CsPbBr3 possess the features of high light-harvesting capacity and fast charge transfer through the LSP resonance effect, thus improving the short-circuit current density and the fill factor. Compared to the original device without Au NPs, a 27.8% enhancement in PCE of plasmonic AuNPs:QD-CsPbBr3/MAPbI3 perovskite solar cells was achieved upon 120 &mu, L Au NP solution doping. This improvement can be attributed to the formation of surface plasmon resonance and light scattering effects in Au NPs embedded in QD-CsPbBr3, resulting in improved light absorption due to plasmonic nanoparticles.

Numerous studies have addressed the use of perovskite materials for fabricating a wide range of optoelectronic devices. This study employs the deposition of an electron transport layer of C60 and an Ag electrode on CH3NH3PbBr3 perovskite crystals to complete a photodetector structure, which exhibits a metal&ndash, semiconductor&ndash, metal (MSM) type structure. First, CH3NH3PbBr3 perovskite crystals were grown by inverse temperature crystallization (ITC) in a pre-heated circulator oven. This oven was able to supply uniform heat for facilitating the growth of high-quality and large-area crystals. Second, the different growth temperatures for CH3NH3PbBr3 perovskite crystals were investigated. The electrical, optical, and morphological characteristics of the perovskite crystals were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visible spectroscopy, and photoluminescence (PL). Finally, the CH3NH3PbBr3 perovskite crystals were observed to form a contact with the Ag/C60 as the photodetector, which revealed a responsivity of 24.5 A/W.

In this study, the perovskite layers were prepared by two-step wet process with different CH3NH3I (MAI) concentrations. The cell structure was glass/FTO/TiO2-mesoporous/CH3NH3PbI3 (MAPbI3)/spiro-OMeTAD/Ag. The MAPbI3 perovskite films were prepared using high and low MAI concentrations in a two-step process. The perovskite films were optimized at different spin coating speed and different annealing temperatures to enhance the power conversion efficiency (PCE) of perovskite solar cells. The PCE of the resulting device based on the different perovskite morphologies was discussed. The PCE of the best cell was up to 17.42%, open circuit voltage of 0.97 V, short current density of 24.06 mA/cm2, and fill factor of 0.747.

In this study, the MAPbBr3 quantum dots (QD-MAPbBr3) were prepared by the simple and rapid method. Octylammonium bromide (OABr) makes the MAPbBr3 with better exciton binding energy, good surface morphology and stability. To form nanocrystalline thin film, the QD-MAPbBr3 was coated by spin-coating method in a nitrogen-filled glove box. The solar cells structure was ITO/NiO x /QD-MAPbBr 3 /C 60 /Ag, where NiO x , QD-MAPbBr 3 , C 60 were used as a hole transport layer, active layer and electron transport layer, respectively. To realize material characteristics, X-ray diffraction (XRD), field-emission scanning electron microscope (FESEM), UV/VIS/NIR spectrometer, and photoluminescence spectrometers (PL) were used to analysis crystallinity, surface morphology, transmittance, and optical behavior of the QD-MAPbBr3 films. The J-V characteristics of devices were evaluated by the solar simulator system.

In this study, the graphene thin films were deposited by reactive radio-frequency magnetron sputter. Then, the graphene thin film was annealing with different temperature in the atmosphere to form graphene oxide (GO) thin films. The solar cell structure was inverted for ITO/Graphene oxide/ CH 3 NH 3 PbI 3 /PCBM/Ag. Photovolatic conversion efficiency of the cells based on the different graphene oxide morphologies was analyzed by XRD, SEM, PL, TR-PL and UV-Vis absorption spectra. The power conversion efficiency of the best cell was 1.75%.

In this work, a MAPbBr3 quantum dot (QD-MAPbBr3) layer was prepared by a simple and rapid method. Octylammonium bromide (OABr) gives the MAPbBr3 better exciton binding energy, good surface morphology, and stability. To form a nanocrystalline thin film on indium tin oxide (ITO) glass, the QD-MAPbBr3 film was coated by a spin-coating method in a nitrogen-filled glove box and the NiOx film was used as an adhesive layer and hole transport layer. The highest transmittance of MAPbBr3 on NiOx/ITO glass was around 75% at 700 nm. This study also reported a high transparent and perovskite bulk-free ITO/NiOx/QD-MAPbBr3/C60/Ag solar cell where the NiOx, QD-MAPbBr3, and C60 were used as a hole transport layer, active layer, and electron transport layer, respectively.

In this experiment, the molybdate phosphors were manufactured by using the solid state amorphization with europium, yttrium and molybdenum. To investigate EuxYy(MoO4)3 phosphor characteristics, the europium and yttrium were blended to different of mole ratio. The europium composition can improve phosphors luminous intensity. Phosphors characteristics was measured by X-ray diffraction, SEM and photoluminescence. The X-ray diffraction and SEM displayed phosphors crystal structure. The photoluminescence of molybdate phosphors show that the best excitation spectra emitting position was at 614nm. The molybdate phosphors was excited by UV laser. Therefore, this molybdate phosphors was suitable for UV-LED.

In this study, the inverse temperature crystallization method was used to produce bulk crystal CH3NH3PbBr3 (MAPbBr3) perovskite, and repeated crystallization processes were carried out to obtain a larger crystal size and develop a bulk material for application in semiconductor devices. The material and optoelectronic properties of the MAPbBr3 perovskite crystals after the repeated processes were characterized. The X-ray diffraction (XRD) patterns of all samples demonstrated a pure perovskite phase. One strong diffraction peak located at 29.4&deg, which corresponds to the (200) perovskite plane, was observed after the first growth cycle. The mobilities for the samples after the first, second, and third growth cycles were calculated and resulted to be 0.9, 5.6, and 54.7 cm2/Vs, respectively, according to Mott&ndash, Gurney law. A higher mobility after the multiple crystallization processes indicated that the surface states caused by voids in the crystals favored electron transition in the perovskite material.