Search

An on-board autonomous task planning system is designed and implemented in this article, aiming at the problem that the current remote sensing satellite needs complex instruction support to perform tasks and depends on the ground system too much. The complex earth observation task description and injection decomposition modules are designed in the system. No more than 128 ordered points describe the curve area task or irregular polygon area task, and the complex task is decomposed into several strips according to the satellite imaging width. Then, the task’s orbit, attitude, mobility, energy, and time constraints are calculated through the modules of on-board orbit prediction, agile attitude calculation, track planning, energy prediction, and visible arc calculation. Finally, the on-board autonomous task planning and execution are completed through task solution space search and metatask command generation modules. The on-orbit flight verification is carried out on the high-resolution multimode (GFDM) satellite. The results show that this paper’s on-board autonomous task planning system can complete complex task injection and autonomous planning and finally execute.

Gels as compelling soft material shows its promising versatility in actuators, soft electronics, and biomedical sensors. However, most gel materials are too rigid to cope with long‐term changing scenarios and specific needs. Inspired by the switchable behavior of bio‐behavior of muscle, the study reports a thermodynamically controllable and stiffness‐transformative cellulose‐salt gel by simple thermal mixing of hydrous salt, cellulose nanofiber, and polyacrylamide. The achieved cellulosic gel with dynamic microstructure presents an amazing stiffness switchability between crystalline state and melted states of 32.38 to 0.02 MPa, as well as the regulable light transmittance between 41.59% and 93.43%. In addition, this cellulose‐salt gel has excellent thermal controllable behavior. That is, by controlling the crystallization process, the cellulose‐salt gel displays the start‐stop releasing‐energy behaviors on demand. Enabled by these outstanding properties, the study further demonstrates the promising application of cellulose‐salt gel in controllable soft‐rigid coupling thermoelectric device, showing the broader implications for wearable electronics aiming at on‐demand work. [ABSTRACT FROM AUTHOR]

Room‐temperature liquid metals (RTLMs) have excellent shape reconfiguration capabilities, which make them ideal for flexible electrodes, sensors, and energy devices. However, due to the high surface tension and weak adhesion of RTLM, the types of printing substrates, patterning, and recovery processes are limited. It is essential to develop advanced encapsulation techniques for the patterning of RTLMs. Lignin has great potential for promotion as nanodispersants and nanocarriers because of its abundant hydroxyl groups and good self‐assembly properties. In this work, a green and facile encapsulation method using industrial lignin is reported for stable, uniform, and reproducible patterning of eutectic gallium–indium (EGaIn). Lignin‐encapsulated EGaIn particles exhibit good stability and can be patterned on the surface of various substrates with a simple ballpoint pen. The electrical resistance of the conductive tracks shows little change under bending and twisting (720°) conditions. More importantly, the lignin‐encapsulated system can be easily dissolved and regenerated, which is also supported by molecular dynamics simulations and density functional theory calculations. 96.9% of the EGaIn can be recovered from the system. These characteristics make it very environmentally friendly throughout the preparation process and find applications in flexible sensors, transient circuits, and many other areas. [ABSTRACT FROM AUTHOR]

As the penetration of distributed wind power in the distribution network continues to increase, the uncertainty of its output has a serious impact on the stable operation of the distribution network. It is difficult to meet the voltage regulation requirements when the wind power fluctuates frequently only by relying on shunt capacitors. Therefore, a coordinated optimization planning method based on soft open point (SOP) and shunt capacitors is proposed. Firstly, the bidirectional generative adversarial network (BIGAN) is used to characterize the uncertainty of wind power output and generate typical scenarios of wind power output. Secondly, a multi-objective optimization planning model of SOP and shunt capacitors is proposed based on the scene analysis method; Then, a solution strategy based on the improved elitist non-dominated sorting genetic algorithm (NSGA-II) is proposed. Finally, the proposed planning model and solution are verified and analyzed in the improved IEEE 33-bus system.

With distributed generation (DG) being continuously connected into distribution networks, the stochastic and fluctuating nature of its power generation brings ever more problems than before, such as increasing operating costs and frequent voltage violations. However, existing robust scheduling methods of flexible resources tend to make rather conservative decisions, resulting in high operation costs. In view of this, a two-stage robust optimal scheduling method for flexible distribution networks is proposed in this paper, based on the pairwise convex hull (PWCH) uncertainty set. A two-stage robust scheduling model is first formulated considering coordination among on-load tap changers, energy storage systems and flexible distribution switches. In the first stage, the temporal correlated OLTCs and energy storage systems are globally scheduled using day-ahead forecasted DG outputs. In the second stage, FDSs are scheduled in real time in each time period based on the first-stage decisions and accurate short-term forecasted DG outputs. The spatial correlation and uncertainties of the outputs of multiple DGs are modeled based on the PWCH, such that the decision conservativeness can be reduced by cutting regions in the box with low probability of occurrence. The improved column-and-constraint generation algorithm is then used to solve the robust optimization model. Through alternating iterations of auxiliary variables and dual variables, the nonconvex bilinear terms induced by the PWCH are eliminated, and the subproblem is significantly accelerated. Test results on the 33-bus distribution system and a realistic 104-bus distribution system validate that the proposed PWCH-based method can obtain much less conservative scheduling schemes than using the box uncertainty set. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of Nanjing University of Aeronautics & Astronautics is the property of Editorial Department of Journal of Nanjing University of Aeronautics & Astronautics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The demand for improved indoor air quality has grown with improvements in the standards of living worldwide. While wood is widely used to construct furniture since it is a renewable resource and aesthetically pleasing, it is also flammable, which limits its applications. Although there have been extensive research efforts in reducing the flammability of wood products, current approaches often have adverse effects on the environment. In this work, a novel organo‐inorganic coordination system is proposed to prepare a fire‐retardant and smoke suppression wooden "air purifier" using a vacuum impregnation method. The "air purifier" is composed of tourmaline particles/KH550 (TPs/KH550) and delignified wood. The added TPs give the final composites capable to purify air (1000 psc cm−3 negative oxygen ions [NOIs]). Compared with pristine wood (PW), total heat release (THR), peak heat release rate (HRR), and smoke production rate (SPR) of the wooden "air purifier" are reduced by 47.88%, 11.73%, and 82.81%, respectively, highlighting that the composites have good fire‐retardancy and smoke suppression performances. Life cycle assessment (LCA) results indicate the composites have minimal environmental impact (EI) in 15 categories. This green, eco‐friendly wooden "air purifier" with fire‐retardant and smoke suppression properties has a great potential application in furniture and buildings. [ABSTRACT FROM AUTHOR]

To reduce carbon dioxide emissions, wind power generation is receiving more attention. The conversion of wind energy into electricity requires frequent use of insulated-gate bipolar transistors (IGBTs). Therefore, it is important to improve their reliability. This study proposed a method to predict the junction temperature of IGBTs, which helps to improve their reliability. Limited by the bad working environment, the physical temperature measurement method proposed by previous research is difficult to apply. Therefore, a junction temperature prediction method based on an extreme learning machine optimized by an improved honey badger algorithm was proposed in this study. First, the data of junction temperature were obtained by the electro-heat coupling model method. Then, the accuracy of the proposed method was verified with the data. The results show that the average absolute error of the proposed method is 0.0303 °C, which is 10.62%, 11.14%, 91.67%, and 95.54% lower than that of the extreme learning machine optimized by a honey badger algorithm, extreme learning machine optimized by a seagull optimization algorithm, extreme learning machine, and back propagation neural network model. Therefore, compared with other models, the proposed method in this paper has higher prediction accuracy. [ABSTRACT FROM AUTHOR]

Transparent wood for smart glass can decrease indoor energy consumption, while simultaneously offering a comfortable indoor temperature and facilitating effective light harvesting. However, high transparency and ultraviolet (UV)‐blocking ability are mutually exclusive in wood‐based materials due to the presence of lignin. Herein, a Turing pattern‐inspired highly transparent wood (TP‐TW) is fabricated via infiltrating the thermal management materials doped‐epoxy (TMM‐epoxy) into the delignified wood with a Turing pattern. Afterward, the Turing pattern possesses outstanding optical properties (high visible transmittance of ≈76% and low UV transmittance of ≈15%). Moreover, TP‐TW can reduce adverse effects caused by indoor temperature fluctuation and outdoor sunlight, demonstrating high latent heat (25.30 J g−1) and low near‐infrared transmittance. Compared with glass, TP‐TW exhibits a low thermal conductivity of 0.21 W m−1 K−1 and excellent shock‐resistant characteristics. Taken together, these results indicate that TP‐TW is an attractive material for smart glass applications. [ABSTRACT FROM AUTHOR]

Most factories discharge untreated wastewater to reduce costs, causing serious environmental problems. Low-cost, biological, environmentally friendly and highly effective materials for the separation of emulsified oil/water mixtures are thus in great demand. In this study, a simple, green method was developed for separating oil-in-water emulsions. A corn straw powder (CSP)-nylon 6,6 membrane (CSPNM) was fabricated by a phase inversion process without any further chemical modification. The CSPNM showed superhydrophilic and underwater superoleophobic properties and could be used for the separation of oil-in-water emulsion with high separation efficiency and flux. The CSPNM maintained excellent separation ability after 20 cycles of separation with an oil rejection >99.60%, and the oil rejection and flux have no obvious change with an increasing number of cycles, suggesting a good antifouling property and the structural stability of CSPNM. In addition, the CSPNM exhibited excellent thermal and chemical stability under harsh conditions of high temperature and varying pH. [ABSTRACT FROM AUTHOR]

Background: With the current rapid economic growth, demands for energy are progressively increasing. Energy shortages have attracted significant attention due to the shrinking availability of non-renewable resources. Therefore, thermal energy storage is one of the solutions that lead to saving of fossil fuels and make systems more cost-effective by the storage of wasted thermal energy. In particular, the application of phase change materials (PCMs) is considered as an effective and efficient approach to thermal energy storage because of the high latent heat storage capacity at small temperature intervals. Nevertheless, leakage problems and low thermal conductivity limit the practical applications of PCMs. Therefore, form-stable phase change materials with high thermal conductivity are urgently needed. Results: A novel form-stable composite phase change material was prepared by incorporating PEG into waste sawdust with 5% EG. In the composites, PEG served as a phase change material, while waste sawdust acted as a carrier matrix. EG was added to help increase the thermal conductivity of the composites. The melting temperature of CPCMs-4 with 5% EG was found to be 58.6 °C with a phase change enthalpy of 145.3 kJ/kg, while the solidifying temperature was 48.5 °C with a phase change enthalpy of 131.4 kJ/kg. The thermal conductivity of CPCMs-4 with 5% EG increased by 23.8% compared with that of CPCMs-4. Moreover, no obvious changes in melting, solidifying temperature, or latent heat after 200 heating-cooling cycles were detected. The supercooling extent of CPCMs-4 with 5% EG decreased by 19.2% compared with PEG. The volume change properties and wettability properties of CPCMs-4 with 5% EG are suitable for thermal energy in terms of practical application. Conclusions: The prepared composites have excellent thermal and form-stable properties and they can be recognized as potential candidates for thermal energy storage as form-stable composite phase change materials. Using simple impregnation techniques with waste sawdust as a supporting material, this study demonstrates an innovative technology for practically and markedly enhancing the adsorption capacity of phase change materials. [ABSTRACT FROM AUTHOR]

Solar desalination technology is an effective approach to produce clean water through evaporating seawater driven by solar energy. However, it remains a great challenge to develop a kind of solar evaporator with high salt-resistance, great stability and superior efficiency. Herein, inspired by wood structure, a polyurethane/chitosan/MXene aerogel with directional channel structure was originally designed as the solar evaporator for desalination by the freeze-casting method. The constructed unique anisotropic three-dimensional (3D) structure enabled the solar evaporator with efficient water transport network, which can effectively improve the salt-rejecting capability. Meanwhile, due to the combination of the full spectral absorption capacity of MXene and the unique directional channel structure, a satisfactory evaporation rate (1.81 kg.m−2 h−1) and high evaporation efficiency (85.07 %) under one-sun irradiation were achieved. Moreover, taking chitosan and waterborne polyurethane (PU) as matrix materials endowed the evaporator with favorable mechanical stability, which made the evaporator continuously achieving high evaporation rate for 12 h under one-sun irradiation and stably floating on the high- concentration salt water for over 14 days. In addition, the evaporator showed excellent salt resistance performance owing to its anisotropic directional channel structure. Also, a series of simulation and numerical modeling were carried out to assist in proving the mechanism of water transportation and desalination in the evaporator. Together, this work may provide a promising avenue for developing an efficient solar evaporator with superior salt blocking ability that could be potentially used for long-term clean water generation. [Display omitted] • The wood-inspired anisotropic channel structure evaporator was acquired through directional freeze casting technology. • Water transport and salt-resistant mechanism were proved by the combination of the experiments and numerical simulation. • MXene nanosheets were selected for efficient photothermal thermogenesis. • Superior salt-resistant property was realized even for high-concentration salt water. [ABSTRACT FROM AUTHOR]

2-Arylsulfonylthiophenes represent a class of important biologically active compounds. Although methods for synthesizing C2-functionalized thiophenes have been extensively reported, research on the synthesis of 2-arylsulfonylthiophenes is extremely rare. Herein, we report a method for 2-arylsulfonylthiophenes via exogenous-oxidant-free electrochemical oxidative C H sulfonylation of thiophenes, which efficiently avoid the issues of desulfonylation or over-reduction of sulfonyl groups. These reactions exhibit broad substrate scope (32 examples) and offer operationally simple, low-cost procedures in a single step. [Display omitted] • A novel electrochemical method enables efficient synthesis of 2-arylsulfonylthiophenes. • The electrochemical approach avoids desulfonylation and over-reduction issues. • The method offers broad substrate scope and simplicity for 2-arylsulfonylthiophenes synthesis. 2-Arylsulfonylthiophenes represent a class of important biologically active compounds. Although methods for synthesizing C2-functionalized thiophenes have been extensively reported, research on the synthesis of 2-arylsulfonylthiophenes is extremely rare. Herein, we report a method for 2-arylsulfonylthiophenes via exogenous-oxidant-free electrochemical oxidative C H sulfonylation of thiophenes, which efficiently avoid the issues of desulfonylation or over-reduction of sulfonyl groups. These reactions exhibit broad substrate scope (32 examples) and offer operationally simple, low-cost procedures in a single step. [ABSTRACT FROM AUTHOR]

[Display omitted] Hypertension is a common chronic disease that can lead to serious health problems. Previous studies have not drawn a consistent conclusion about the effect of proanthocyanidins (PCs) on blood pressure (BP). This systematic review and meta-analysis aims to evaluate the effect of PCs supplementation on blood pressure (BP). A comprehensive literature search was performed in 6 databases (Pubmed, Scopus, ISI Web of Science, the Cochrane Library, Embase and Google Scholar) to identify the randomized controlled trials (RCTs) that evaluated the BP-lowering effect of PCs. Subgroup and sensitivity analyses were conducted to evaluate the potential heterogeneity. Meta-regression analysis was used to evaluate dose effects of PCs on BP. A total of 6 studies comprising 376 subjects were included in our meta-analysis to estimate the pooled effect size. This meta-analysis suggested that PCs supplementation could significantly reduce systolic blood pressure (SBP) (WMD: -4.598 mmHg; 95 % CI: -8.037, -1.159; I2 = 33.7 %; p = 0.009), diastolic blood pressure (DBP) (WMD: -2.750 mmHg; 95 % CI: -5.087, -0.412; I2 = 0.0 %; p = 0.021) and mean arterial pressure (MAP) (WMD: -3.366 mmHg; 95 % CI: -6.719, -0.041 mmHg; I2 = 0.0 %; p = 0.049), but had no significant effect on pulse pressure (PP) (WMD: -2.131 mmHg; 95 % CI: -6.292, 2.030; I2 = 0.0 %; p = 0.315). When the studies were stratified according to the duration of the study, there was a significant reduction on SBP in the subset of the trials with <12 weeks of duration. On the contrary, there was a significant reduction on DBP in the subset of the trials with ≥12 weeks of duration. The Subgroup analysis by BMI indicated that a significant reduction on SBP for people with a higher BMI (BMI ≥ 25) and a significant reduction on DBP for people with a lower BMI (BMI < 25). Additional subgroup analysis revealed low-dose-PCs (<245 mg/day) could significantly reduce SBP, DBP and MAP. The meta-regression analyses did not indicate the dose effects of PCs on SBP, DBP, PP and MAP. Based on the current findings, PCs supplementation may be a useful treatment of hypertensive patients as well as a preventive measure in the prehypertensive and healthy subjects. However, further investigation is needed to confirm these results. [ABSTRACT FROM AUTHOR]