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The far-ultraviolet main auroral emission at Jupiter – Part 2: Vertical emission profile
摘要： The aurorae at Jupiter are made up of many different features associated with a variety of generation mechanisms. The main auroral emission, also known as the main oval, is the most prominent of them as it accounts for approximately half of the total power emitted by the aurorae in the ultraviolet range. The energy of the precipitating electrons is a crucial parameter to characterize the processes at play which give rise to these auroral emissions, and the altitude of the emissions directly depends on this energy. Here we make use of far-UV (FUV) images acquired with the Advanced Camera for Surveys on board the Hubble Space Telescope and spectra acquired with the Space Telescope Imaging Spectrograph to measure the vertical profile of the main emissions. The altitude of the brightness peak as seen above the limb is ～ 400 km, which is significantly higher than the 250 km measured in the post-dusk sector by Galileo in the visible domain. However, a detailed analysis of the effect of hydrocarbon absorption, including both simulations and FUV spectral observations, indicates that FUV apparent vertical profiles should be considered with caution, as these observations are not incompatible with an emission peak located at 250 km. The analysis also calls for spectral observations to be carried out with an optimized geometry in order to remove observational ambiguities.
关键词： Atmospheric composition and structure (airglow and aurora),magnetospheric physics (auroral phenomena; current systems)
更新于2025-09-19 17:15:36
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Estimation of structural composition of the inverse spinel ferrites using 57Fe-Zero Field Nuclear Magnetic Resonance
摘要： We have demonstrated 57Fe Zero Field Nuclear Magnetic Resonance (ZFNMR) as a powerful tool in determining the structural composition of nickel-cadmium spinel ferrites of various compositions of Ni1-x Cdx Fe2O4 from x = 0 to1, which are synthesized via one-step auto combustion technique. The XRD measurements confirm the phase purity of all the samples. Vibrating Sample Magnetometry (VSM) measurements show that saturation magnetization (MS) increases initially (up to x = 0.3) and then decreases for higher concentrations of cadmium. The Fe3+ ions in the inverted spinel ferrite distribute equally among two possible sites (tetrahedral A and octahedral B) with different hyperfine fields. Therefore for x = 0 under the assumption that Ni enters B sites, 57Fe NMR of Fe3+ ions yield two signals of equal integral intensities in spectral lines corresponding to these sites. Thus, for the sample series Ni1-x Cdx Fe2O4, the contribution of Fe3+ nuclei varies for A and B sub-spectra with the substitution of a non-magnetic Cd2+ ion. By measuring the Fe3+ distribution on A and B sites which is determined from relative spectral areas of A and B NMR sub-spectra the cation distribution is estimated and has been verified by the binomial distribution. Further, XRD Rietveld refinement results are also in good agreement with the composition estimated by NMR technique and the ideal composition. We have demonstrated the usefulness of NMR technique to quantify the accurate composition of the mixed spinel ferrite systems using Ni-Cd ferrite as a test case. Further, the estimated of inversion parameter (at around x = 0.4), for the studied system, obtained from ZFNMR, XRD, and VSM techniques are in excellent agreement with each other.
关键词： Structural composition,Binomial distribution,VSM,57Fe Zero Field NMR,mixed spinels
更新于2025-09-19 17:15:36
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Study of the phase composition and tribological properties of carbon tool steels after laser surface hardening by quasi - CW fiber laser
摘要： The paper contains the investigation results on the structure and phase composition of the laser radiation area (LRA) of the U8 and U10 steels over its entire thickness. In the present study, the laser surface hardening of both U8 (ASTM - W1-7) and U10 (ASTM - W1-9) steels in the air was performed by exploiting a quasi - CW fiber laser with a 130 W power and 3 mm/s processing speed. The phase composition of the oxide layer formed as a result of laser treatment (LT) in air, as well as the structure of the oxide-metal interface on the surface of U8 (ASTM–W1-7) and U10 (ASTM–W1-9) carbon tool steels were studied by X-ray photoelectron spectroscopy (XPS). It was established that the thickness of the completely oxidized surface layers for U8 and U10 steels is 38.7 nm and 99 nm, respectively. The composition of the oxides of the steel surface after LT was determined. The presence of a wüstite-based film on U8 steel evidences the low wear properties of the LRA surface, while the thicker oxide layer of the modified U10 steel which contains Fe2O3 and Fe3O4 oxides with better strength properties, on the contrary, provides U10 steel surface with higher wear resistance. It was found that the wear rate of U10 steel modified surface decreases by more than two times, while the given value for U8 steel reduces no more than 17%. The paper reports the metallographic examination of the LRA structure. It was shown that the wear-resistant structural components that appeared after laser treatment lead to an increase in the deformation properties of steels. The maximum microhardness value of the LRA is 710 HV0.1 for U8 steel and 750 HV0.1for U10 steel.
关键词： Laser radiation,Oxidized surface layers,X-ray photoelectron spectroscopy,Phase composition,Surface finishing treatment,Elemental composition
更新于2025-09-19 17:13:59
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Introducing Enumerative Sphere Shaping for Optical Communication Systems with Short Blocklengths
摘要： Probabilistic shaping based on constant composition distribution matching (CCDM) has received considerable attention as a way to increase the capacity of fiber optical communication systems. CCDM suffers from significant rate loss at short blocklengths and requires long blocklengths to achieve high shaping gain, which makes its implementation very challenging. In this paper, we propose to use enumerative sphere shaping (ESS) and investigate its performance for the nonlinear fiber optical channel. ESS has lower rate loss than CCDM at the same shaping rate, which makes it a suitable candidate to be implemented in real-time high-speed optical systems. In this paper, we first show that finite blocklength ESS and CCDM exhibit higher effective signal-to-noise ratio than their infinite blocklength counterparts. These results show that for the nonlinear fiber optical channel, large blocklengths should be avoided. We then show that for a 400 Gb/s dual-polarization 64-QAM WDM transmission system, ESS with short blocklengths outperforms both uniform signaling and CCDM. Gains in terms of both bit-metric decoding rate and bit-error rate are presented. ESS with a blocklength of 200 is shown to provide an extension reach of about 200 km in comparison with CCDM with the same blocklength. The obtained reach increase of ESS with a blocklength of 200 over uniform signaling is approximately 450 km (approximately 19%).
关键词： optical communication systems,enumerative sphere shaping,probabilistic shaping,fiber nonlinearity,Constant composition distribution matching
更新于2025-09-19 17:13:59
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Generation of transgenic zebrafish with 2 populations of RFP- and GFP-labeled thrombocytes: analysis of their lipids
摘要： Zebrafish thrombocytes are similar to mammalian platelets. Mammals have young platelets (also called reticulated platelets) and mature platelets. Likewise, zebrafish have 2 populations of thrombocytes; one is DiI-C18 (DiI)+ (DP), and the other is DiI? (DN). However, the mechanism of selective thrombocyte labeling by DiI is unknown. Furthermore, there is no transgenic zebrafish line where DP and DN thrombocytes are differentially labeled with fluorescent proteins. In this study, we found that Glo fish, in which the myosin light chain 2 promoter drives the rfp gene, have a population of thrombocytes that are red fluorescent protein (RFP) labeled. We also generated transgenic GloFli fish in which DP and DN thrombocytes are labeled with RFP and green fluorescent protein (GFP), respectively. Single-cell lipid analysis showed a twofold increase in phosphatidylethanolamine (PE) and a twofold decrease in phosphatidylcholine (PC) in RFP+ thrombocytes compared with GFP+ thrombocytes, suggesting that lipid composition may be important for DiI differential labeling. Therefore, we tested liposomes prepared with different ratios of PC and PE and observed that liposomes prepared with higher amounts of PE favor DiI labeling, whereas the PC concentration had a modest effect. In liposomes prepared using only PE or PC, increased concentrations of PE resulted in increased DiI binding. These results suggest that because RFP+ thrombocytes have higher PE concentrations, DiI may bind to them efficiently, thus explaining the selective labeling of thrombocytes by DiI. This work also provides GloFli fish that should be useful in understanding the mechanism of thrombocyte maturation.
关键词： lipid composition,RFP,phosphatidylcholine,GFP,DiI,phosphatidylethanolamine,thrombocytes,zebrafish
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 60th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON) - Riga, Latvia (2019.10.7-2019.10.9)] 2019 IEEE 60th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON) - A Study on the Development of a 1 MW Grid-Connected Photovoltaic Inverter System
摘要： Spurred by Web technologies and service computing paradigm, more and more Web services have been delivered via standardized interfaces on the Internet. Mashup is exactly an enabling technology for end-users to combine these services into applications. However, there are some issues of end-user service development with mashup techniques. It not only requires users that develop application logics equipped with more or less programming skills, but also lacks a lightweight mashup model and systematic development approach in the existing mashup tools. To address these issues, we propose a data-driven service creation approach to facilitate application development and deployment. In the approach, we propose the service data model (SDM) for adaptation of heterogeneous Web services, the service relation model (SRM) for representation and re?nement of data interaction between services, and the service process graph (SPG) for describing business logics of mashup applications. We develop an IFrame implementation for SDM that can facilitate service providers to wrap heterogeneous Web services in a uni?ed way and display a visual element for the service. Meanwhile, we implement a pipeline as an intuitive form of SRM that can be used by end-users to develop business logic more effectively. To adapt the dynamic application scenarios, we also construct an event-driven execution mechanism for SPG. A lightweight service creation environment is then implemented to support end-users to develop applications in a simulative way, and a corresponding development methodology is introduced for this tool. Finally, the end-user evaluation and performance evaluation are conducted to evaluate our platform.
关键词： service composition,dataflow,Lightweight service creation,mashup,end-user development
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE International Ultrasonics Symposium (IUS) - Glasgow, United Kingdom (2019.10.6-2019.10.9)] 2019 IEEE International Ultrasonics Symposium (IUS) - Integrated Ultrasound and Photoacoustic Imaging for Effective Endovenous Laser Ablation: A Characterization Study
摘要： A Taguchi particle swarm optimization (TPSO) with a three-layer feedforward artificial neural network (ANN) is used to model and optimize the chemical composition of a steel bar. The novel contribution of a TPSO is the use of a Taguchi method mechanism to exploit better solutions in the search space through iterations, the use of the conventional non-linear PSO to increase convergence speed, and the use of random movement for particle diversity. The exploration and exploitation capability of the TPSO were confirmed by performance comparisons with other PSO-based algorithms in solving high-dimensional global numerical optimization problems. Experiments in this paper showed that the TPSO provides higher computational efficiency and higher robustness when solving problems involving seven non-linear benchmark functions, including three unimodal functions, one multimodal functions, two rotated functions, and one shifted functions. The results for the computational experiments show that the TPSO outperforms other PSO-based algorithms reported in the literature. Finally, the results obtained by a TPSO-based ANN model of the chemical composition of the steel bar were consistent with the actual data. That is, the proposed TPSO with three-layer feedforward ANN can be used in practical applications.
关键词： yield point,feedforward artificial neural network,tensile strength,particle swarm optimization,chemical composition of steel bar,Taguchi method
更新于2025-09-19 17:13:59
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Impact of Perovskite Composition on Film Formation Quality and Photophysical Properties for Flexible Perovskite Solar Cells
摘要： In recent years, ?exible perovskite solar cells have drawn tremendous attention in the ?eld of wearable devices, and optimization of perovskite composition plays an important role in improving ?lm quality and photophysical properties. At present, some researchers have only studied A-site organic cations mixing or X-site halide anions mixing in the ABX3 structure of perovskite, but there are few reports on co-mixing of A-site and X-site ions in ?exible perovskite solar cells. In this paper, we mainly try to study the e?ects of di?erent concentrations of mixed formamidine methylamine halide (FAxMA1-xBrxClyI1-x-y) precursor solutions on the quality and photophysical properties of perovskite ?lms under low temperature process. We conclude that the ?lm quality and photophysical properties reached the best results when the optimized precursor solution concentration was 60:6:6. The investigation on composition optimization in this experiment laid the foundation for the improvement of the performance of ?exible perovskite solar cells. We also use the results of this experiment to prepare ?exible perovskite solar cells based on carbon electrodes, which are expected to be applied in other ?exible optoelectronic or electro-optical devices.
关键词： photophysical properties,perovskite composition,?lm quality,?exible perovskite solar cells
更新于2025-09-19 17:13:59
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Correlating Hysteresis and Stability with Organic Cation Composition in the Two-Step Solution-Processed Perovskite Solar Cells
摘要： The two-step solution-based process has demonstrated substantial success in fabricating high-efficiency perovskite solar cells in recent years. Despite the high performance, the underlying mechanisms that govern the formation of perovskite films and corresponding device performance are yet to be fully understood. Particularly, organic cation composition used in the two-step solution processing of mixed-cation lead halide perovskite solar cells plays a critical role in the perovskite film formation and the resultant device performance. However, little is understood about the impacts of organic cation composition on the current density-voltage (J-V) hysteretic behavior and stability of perovskite solar cells. To address this need, here, we study the effect of mixed organic cations, i.e., the fraction of formamidinium (FA) and methylammonium (MA) contents, used for the two-step solution-processed perovskite thin films on solar cell performance, including efficiency, J-V hysteresis, and stability. In addition to the efficiency variations, we find that perovskite solar cells based on FA-rich and MA-rich stoichiometries show distinct characteristics in J-V hysteresis and stability. The origins of such a discrepancy are attributed to the thermodynamically driven conversion from lead iodide to perovskites, which is determined by the combination of organic cations. The perovskite solar cells based on the mixed cation FA0.6MA0.4PbI3 composition show a champion power conversion efficiency of over 21% and robust stability (retaining more than 90% of initial efficiency) under maximum power point tracking in dry nitrogen for more than 500 hours. Our work provides insights on understanding the formation of perovskite films in the two-step process, which may benefit further investigation on perovskite solar cells.
关键词： stability,Perovskite solar cells,two-step process,J-V hysteresis,organic cation composition
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE International Conference on Electrical, Computer and Communication Technologies (ICECCT) - Coimbatore, India (2019.2.20-2019.2.22)] 2019 IEEE International Conference on Electrical, Computer and Communication Technologies (ICECCT) - Characterisation and performance evaluation of amorphous silicon nitride as passivation layer in thin film aSi:H solar cells
摘要： The fabrication and characterisation of amorphous silicon nitride layer is presented in this paper. The suitability of using it in photovoltaic application has been investigated. It is observed that the band gap of the nitride layers increases with increase in nitrogen content. The experimental results shows that amorphous silicon nitride alloy can be used as passivation layer in devices due to its high optical band gap. On the basis of experimental results, a thin ?lm aSi:H single junction solar cell having aSiNx as passivation layer has been proposed. Further, the behaviour of the proposed structure has been evaluated through simulation using SCAPS1D solar simulator. It is found out that the involvment of amorphous silicon nitride as passivation layer on the top part of the solar cell results in a conversion ef?ciency of 12.9 % and short circuit current density (Jsc) of 15.18 mA/cm2 which are signi?cant values as far as a single junction amorphous silicon thin ?lm solar cell has been considered. Furthermore, a comparison study on solar cell performance parameters of aSi:H solar cell with and without aSiNx passivation layer has been done.
关键词： composition pro?le,optical band gap,FTIR spectrum,passivation layer,PECVD,conversion ef?ciency
更新于2025-09-16 10:30:52