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Optically controlled millimetre-wave switch with stepped-impedance lines
摘要： Nitrogen (N) placement can impact nitrogen use efficiency, but its effect on greenhouse gas (GHG) emissions remain unclear. The objective of this study is to compare the effects of four different N horizontal placement methods (i.e., annular canal (An), radial canal (Ra), band (Ba), and nest fertilization (Ne)) with urea broadcast (Br) on nitrous oxide (N2O), methane (CH4), and soil heterotrophic respiration carbon dioxide (CO2) emissions from an apple orchard to assess the seasonal and spatial variations in these gas emissions. The total cumulative GHG emissions are determined through spots that are differentiated as fertilized or unfertilized. A field simulation study is conducted in an apple orchard, and all N sources have an application rate of 300 kg N ha?1. from the Br treatment are significantly lower than those of other treatments, and the emissions from the Ne treatment are 1.7-fold higher than those of the Br treatment. Surprisingly, the cumulative N2O emissions from the Br treatment are significantly higher than those of the other four treatments. N horizontal placement does not significantly influence the soil CH4 sink. The CO2 emissions in the Br treatment are higher than in other treatments. High N2O emissions in the Br treatment result in a significantly higher GHG exchange than in other treatments, while the Ne treatment significantly reduces the GHG exchange throughout the measurement period. Therefore, optimizing N placement may serve as an effective way to reduce GHG emissions from arable soils.
关键词： nitrogen placement,nitrous oxide,nest fertilization,greenhouse gas emissions,nitrogen use efficiency
更新于2025-09-23 15:19:57
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Engineering Quantum Dots with Ionic Liquid: A Multifunctional White Light Emitting Hydrogel for Enzyme Packaging
摘要： Herein, a new and straightforward approach for the fabrication of a stable and multifunctional white light emitting (WLE) hydrogel is reported. For the first time, the utility of such hydrogels for protein packaging with enhanced activity and stability is presented. Initially, a WLE composite with color chromaticity of (0.33, 0.27) is fabricated by engineering the surface of an orange light emitting Mn2+-doped ZnS quantum dot (QD) using a blue-emitting choline-tosylate ionic liquid (IL). The color chromaticity can be tuned by altering the concentration of the IL and excitation wavelengths. The WLE hydrogel is constructed through the conjugation of the WLE QD-IL composite with an alginate biopolymer. Remarkably, the WLE QD-IL composite and WLE hydrogel show preservation of their structural and luminescence properties for an extended time and thus indicate a potential for storage applications. When cytochrome c (Cyt C) is caged within the WLE hydrogel matrix, the peroxidase activity increases by more than 1.7-times compared with native Cyt C and a Cyt C-loaded QD hydrogel at room temperature. Also, Cyt C-immobilized WLE hydrogel shows a 3.5-fold increase in activity (compared with native Cyt C) at a higher temperature (120 °C) and in the presence of a denaturation agent.
关键词： ionic liquids,hydrogels,cytochrome C,white light emissions,quantum dots
更新于2025-09-23 15:19:57
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Performance analysis of photovoltaic-thermal air collectors combined with a water to air heat exchanger for renewed air conditioning in building
摘要： In this work, a new solar system that includes photovoltaic-thermal (PVT) air collectors coupled to a water-to-air heat exchanger is investigated. The considered system generates sufficient energy for cooling and heating of the ambient air injected in a 300 m2 tertiary building and saves its total energy consumption. Therefore, it allows the minimization of greenhouse gas emissions of the building. A numerical model is developed to ensure comfortable temperatures during summer and winter, including days with the highest energy needs. The results show that the proposed system can generate the required heating and cooling needs using an airflow rate equal to 0.25 kg/s and a PVT area of 17 m2. It was found that the coupling of the PVT air collectors with a water to air heat exchanger minimizes the total required area for heating by ~ 33%. Moreover, the PV module’s efficiency was enhanced by 2.0% in winter and 5.1% in summer. The thermal energy saved for heating, thermal energy saved for cooling and the electrical energy saved are, respectively, equal to 15.30 kWh/day, 24.79 kWh/day, and 3.14 kWh/day. This represents an average emission reduction of 11.4 kg CO2 per day.
关键词： Water to air heat exchanger,Energy saving,Thermal comfort in buildings,Photovoltaic air collectors,Renewable energies,Greenhouse gas emissions
更新于2025-09-23 15:19:57
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Realizing bright blue-red color-tunable emissions from Gd2GeO5:Bi3+,Eu3+ phosphors through energy transfer toward light-emitting diodes
摘要： Novel Bi3t, Eu3t co-doped Gd2GeO5 (GGO) phosphors were prepared by a high-temperature solid-state reaction method. X-ray diffraction, photoluminescence (PL), CIE chromaticity coordinates, internal quantum efficiency (IQE), and temperature-dependent PL spectra were applied to analyze the as-obtained phosphors. The emission spectra of the GGO:Bi3t, Eu3t phosphors showed both a broad blue band of Bi3t ions emission centered at 453 nm and the characteristic sharp red emission lines of Eu3t ions, corresponding to the 3P1→1S0 allowed transition of the Bi3t ions and the 5D0→7FJ (J ? 0, 1, 2, 3, 4) transitions of the Eu3t ions, respectively. Notably, the as-prepared GGO:Bi3t, Eu3t phosphors exhibited color-tunable emissions from blue (Bi3t) to red (Eu3t) with increasing the Eu3t doping concentration via a high-efficiency energy transfer process. Moreover, the mechanism of energy transfer from Bi3t to Eu3t ions was determined to be the dipole-quadrupole interaction. Impressively, the optimal GGO:0.05Bi3t, 0.12Eu3t phosphors had an outstanding IQE as great as 88% and good thermal stability. All these meaningful results demonstrated that blue-red color-tunable GGO:Bi3t, Eu3t phosphors have potential applications in white light-emitting diodes (LEDs) and plant growth LEDs.
关键词： Gd2GeO5,Energy transfer,Phosphors,Eu3t,Bi3t,Color-tunable emissions
更新于2025-09-23 15:19:57
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Plasma chemistry produced during laser ablation of graphite in air, argon, helium and nitrogen
摘要： Laser-induced plasma chemistry produced during the ablation of graphite targets at atmospheric pressure in air, argon, helium and nitrogen was studied through time-resolved atomic and molecular emission spectroscopy. The plasma plume and plasma chemistry were generated by focusing a 6-mm diameter, 212 mJ, 1064-nm nanosecond Nd:YAG laser to a spot size of about 1 mm diameter over graphite samples of 99.9% pureness. The atomic emissions C I 247.86 nm, N I 821.50 nm and O I 777.19 nm, and the molecular bands C2 (473.71 nm) and CN (359.04 nm and 388.30 nm) were monitored as a function of time (0.2 to 220 μs). While the C I and C2 emissions followed a near-exponential decay, the CN emission in air and nitrogen showed an emission behavior characterized by two local maxima at 0.2 μs and 20-30 μs after the plasma ignition. The first maximum was explained by the early plasma chemistry produced by the ablated carbon species and the confining background gas, whereas the second maximum was attributed to atomic recombination and shock wave-induced excitation of the plasma plume. Two main effects were observed when the ablation was produced in different background gases. First, the presence of oxygen (≈21%) in air had a negligible effect on atomic lines; however, the CN emission intensity and lifetime were significantly reduced in comparison with an atmosphere of 100% nitrogen. This was attributed to the reduction of nitrogen species as reaction partners during the plasma chemistry in air. Secondly, due to the assumed higher plasma temperature in Ar, this gas favored the emission intensity and lifetime of atomic species but hindered the formation of C2 species. Because the collection optics of the emission spectroscopy system was configured in backscatter mode, which integrates over the entire plasma volume and gate time without spatial resolution, the time-resolved behavior of the plasma emissions were only related to the number density of emitters but not to specific locations in the plasma volume.
关键词： Atomic-molecular emissions,Laser-induced breakdown spectroscopy,Plasma chemistry,Graphite
更新于2025-09-23 15:19:57
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Comparison study of temperature dependent direct/indirect bandgap emissions of Ge1-x-ySixSny and Ge1-ySny grown on Ge buffered Si
摘要： Temperature-dependent photoluminescence (PL) of two sets of ternary samples with fixed tin concentrations of ~5.2% (Ge0.924Si0.024Sn0.052, and Ge0.911Si0.036Sn0.053) and ~7.3% (Ge0.90Si0.027Sn0.073, and Ge0.888Si0.04Sn0.072) were measured along with their binary counterparts (Ge0.948Sn0.052 and Ge0.925Sn0.075). The variations of direct bandgap emission (ED) and indirect bandgap emission (EID) with temperature were studied for both ternary and binary alloys by means of Gaussian curve fitting, and the results are compared. The bandgap widths of ternaries clearly increase after Si incorporation into the GeSn with similar Sn concentrations. It is found that for the ternaries both ED and EID peak energies are blue shifted, and the energy separation of ED and EID peaks becomes larger than that of binaries for similar Sn concentrations. Moreover, both ED and EID peaks appear at room temperature (RT) in the GeSiSn spectra, but the ED peak position is greater than EID, indicating these ternaries are indirect bandgap materials. Low temperature PL validates the existence of indirect PL emission in Ge0.90Si0.027Sn0.073 and direct gap behavior in Ge0.925Sn0.075, indicating GeSn becomes a direct bandgap material at lower Sn concentration than GeSiSn. The PL intensities of these ternaries are generally weaker and the spectra become more complicated than those of binaries, probably due to increased strain and defects in the ternaries. Finally, it is found that the effect of large differences in strain of ternary samples on PL peak positions can be greater than that of small Si composition differences in ternaries. A large compressive strain in ternaries can also make splitting of the ED into ED,HH (conduction band minimum-Γ valley to heavy hole maximum) and ED,LH (conduction band minimum-Γ valley to light hole maximum) transitions more observable in the PL spectra.
关键词： strain,germanium tin,photoluminescence,direct/indirect bandgap emissions,valence band splitting,germanium silicon tin
更新于2025-09-19 17:15:36
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Measuring SO<sub>2</sub> ship emissions with an ultraviolet imaging camera
摘要： Over the last few years fast-sampling ultraviolet (UV) imaging cameras have been developed for use in measuring SO2 emissions from industrial sources (e.g. power plants; typical emission rates ～ 1–10 kg s?1) and natural sources (e.g. volcanoes; typical emission rates ～ 10–100 kg s?1). Generally, measurements have been made from sources rich in SO2 with high concentrations and emission rates. In this work, for the ?rst time, a UV camera has been used to measure the much lower concentrations and emission rates of SO2 (typical emission rates ～ 0.01–0.1 kg s?1) in the plumes from moving and stationary ships. Some innovations and trade-offs have been made so that estimates of the emission rates and path concentrations can be retrieved in real time. Field experiments were conducted at Kongsfjord in Ny ?lesund, Svalbard, where SO2 emissions from cruise ships were made, and at the port of Rotterdam, Netherlands, measuring emissions from more than 10 different container and cargo ships. In all cases SO2 path concentrations could be estimated and emission rates determined by measuring ship plume speeds simultaneously using the camera, or by using surface wind speed data from an independent source. Accuracies were compromised in some cases because of the presence of particulates in some ship emissions and the restriction of single-?lter UV imagery, a requirement for fast-sampling (> 10 Hz) from a single camera. Despite the ease of use and ability to determine SO2 emission rates from the UV camera system, the limitation in accuracy and precision suggest that the system may only be used under rather ideal circumstances and that currently the technology needs further development to serve as a method to monitor ship emissions for regulatory purposes. A dual-camera system or a single, dual-?lter camera is required in order to properly correct for the effects of particulates in ship plumes.
关键词： SO2 emissions,ship plumes,UV camera,particulates,atmospheric measurement
更新于2025-09-19 17:15:36
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - New Phase Modulator with Large Stroke and High Bandwidth for Improved Coherent Coupling Schemes
摘要： High-frequency signals on interconnects can cause significant radiated electromagnetic emissions. An intermediate level modeling method aimed at providing a faster solution with less computing resources to allow designers to obtain rapid approximations is desirable. This paper presents a modeling technique to speed up the evaluation of radiated fields from interconnect cables. Based on the Hertzian dipole radiation theory and transmission-line frequency-dependant solutions, the radiating source is modeled by the sum of a large number of short dipoles. This model allows the contributions of line-end discontinuities to be included through a vector network analyzer measurement together with a monopole approximation. The proposed method is verified by open-line and RG 58 coaxial cable measurements.
关键词： radiated electromagnetic emissions,Dipole radiation,transmission-line (TL) modeling,electromagnetic compatibility
更新于2025-09-19 17:13:59
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Light absorption by organic aerosol emissions rivals that of black carbon from residential biomass fuels in South Asia
摘要： Solid biomass fuel-based residential cookstoves are the largest source of aerosol emissions in the Indian subcontinent. For assessing radiative forcing due to this pollutant source, laboratory-generated cookstove performance datasets are currently used, which have established black carbon (BC) as the dominant atmospheric warming aerosol species. We report findings on the strong near-ultraviolet wavelength absorption characteristics of emitted organic carbon (OC) aerosol from household stove combustion of nationally-representative biomass fuels. OC emission from cookstoves have been conventionally parameterized in emission inventory and regional climate models to be non-light-absorbing in the visible solar spectra. We conclude that light-absorbing OC contributes roughly as much as BC to total absorption cross-sections, thereby enhancing the associated positive forcing estimates. Our findings underscore the importance of including light-absorbing OC within the subcontinent’s air quality and climate impact assessment frameworks.
关键词： South Asia,black carbon,radiative forcing,biomass fuels,organic carbon,light absorption,cookstoves,aerosol emissions
更新于2025-09-19 17:13:59
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Near-Field Radio Holography of Slant-Axis Terahertz Antennas
摘要： Principal component analysis (PCA) and independent component analysis (ICA) for radiated emissions from printed circuits are critically intercompared, revealing similarities and differences of the extracted components between both methods. The input data in this analysis are measured wideband complex-valued magnetic radiated and evanescent fields with quasi-Gaussian spatial distributions. PCA and ICA lead to similar maps of their components when considered as spatial eigenmodes, but independent components exhibit simpler field structure than principal components.
关键词： stochastic fields,principal component analysis (PCA),uncertainty quantification,Independent component analysis (ICA),radiated emissions
更新于2025-09-19 17:13:59