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The orbit solution of near-Earth asteroids heavily relies on ground-based optical observations. The orbit uncertainty is limited by the insufficient observation quantity and quality. The Chinese Tianwen-2 mission targets a near-Earth asteroid (469219) Kamo'oalewa and a main-belt comet, 311P/PANSTARRS. To accurately determine the orbit of Kamo'oalewa, more optical observations are needed. Autonomous observation experiments focusing on Kamo'oalewa were carried out using the 2.16-m telescope at the Xinglong Observatory of the National Astronomical Observatory of China. We found that this telescope could observe near-Earth asteroids as faint as a magnitude of 22.8. Based on the stacking method and trailed star extraction algorithm, 14 optical observations were obtained from 2022 to 2024. The orbit for Kamo'oalewa was determined by combining our observations with historical observations between 2004 and 2024. The inclusion of our observations results in improved orbital uncertainties of Kamo'oalewa by 18.67, 7.93, and 11.12 km (1σ) in the X, Y , and Z directions, respectively. Furthermore, by combining all existing and simulated observations, the uncertainty of the orbital determination of Kamo'oalewa was analysed. When using an additional 180 group observations from 3 Chinese observatories over 2 yr, the orbital uncertainties of Kamo'oalewa in the 3 directions could be reduced to 30 km (1σ). [ABSTRACT FROM AUTHOR]

China's lunar exploration program has developed and progressed for more than 13 years. Over this time, Precise Orbit Determination (POD) has guaranteed successful execution of the Chang'e missions, and is the basis for further scientific investigations using radio science data; for example, recovering the lunar gravity field to explore the inner structure and detect craters to study the evolutionary history of the moon. This study briefly reviews the Chang'e series mission orbit and radio tracking measurements. We reprocessed the tracking data and comprehensively summarized the evolution of the POD accuracy and the tracking system precision from the Chang'e 1 to Chang'e 4 missions using in‐house software. Our results show a progression of the tracking station, as the first Chang'e 1 mission only reached several millimeters per second level accuracy in the Doppler measurements and several meters level accuracy for the two‐way range measurements. Later on the accuracy of Chang'e 5T1 Doppler measurements reached about 0.35 mm/s and the accuracy of the Chang'e 3 two‐way range measurements below 0.7 m. Moreover, the newest Chang'e 4 relay satellite achieved POD residuals Root Mean Square for the two‐way range less than a meter and orbital accuracy at 200 m level, in contrast to meters level residual and the half‐kilometer level accuracy achieved during the Chang'e 1 mission. We can clearly see that the POD performance of the Chang'e spacecraft continuously improved. This research study is a reference for future Chinese Lunar exploration missions, as well as Chinese Mars and asteroid explorations. Key Points: We first summarized orbital geometry, tracking network and its tracking strategies of all Chang'e missionsWe have processed the tracking data on the orbiting phase, from Chang'e 1 to Chang'e 4, and concluded its orbit accuracyMoreover, we also displayed some puzzling points which happened in Chang'e 1 and 2 missions in tracking data and answered them [ABSTRACT FROM AUTHOR]

The precise positioning of a lander is a key issue during in situ planetary exploration. This paper proposes an optimal weighting algorithm based on a Helmert-variance component estimation applied to VLBI phase delay data. We validated our algorithm on Chang'e 3 lander VLBI phase delay from the Chinese VLBI Network. We consider that the lander positioning accuracy achieved with our new algorithm is at least 53 % better, compared to previous estimations based on the same observations. The position of the lander based on continuous 4-day observations was estimated to be 44.1215 ° N (± 21.9 m), −19.5135 ° E (± 4.2 m) and −2632.7 m (± 18.9 m) with respect to a moon reference system. This result agrees well with the position derived from images taken by the Narrow Angle Camera on the Lunar Reconnaissance Orbiter. [ABSTRACT FROM AUTHOR]

In this paper, a dual-electrode gas switch triggered by ejected plasma is proposed to ensure the switch to be triggered reliably under extremely low switching coefficient. The switch has the configuration of dual electrodes, in one of which a microincentive chamber is embedded to develop ejected plasma into the switch gap, leading to the breakdown of the switch. Both the features of ejected plasma and the triggering discharge characteristics of the switch are studied with different types of gas, gas pressures, voltage polarities, gap distances, triggering pulse energies, and so on. The results show that the switch can be triggered reliably in a much wide working voltage range, as the minimum switching coefficient is low to 9% with the delay time of about 10 \mu \texts . With the decrease of gas pressure and the increase of triggering pulse energy, the height of ejected plasma increases while the delay time of the switch reduces. The polarities of charging voltage and triggering voltage both have obvious influence on the delay time of the switch, and the effect of the former is greater. Under the same gas pressure and triggering pulse energy, the delay time in SF6 is much bigger than that in N2. [ABSTRACT FROM PUBLISHER]

Background: Licorice (Glycyrrhiza uralensis Fisch.), a well-known traditional medicine, is traditionally used for the treatment of respiratory disorders, such as cough, sore throat, asthma and bronchitis. We aim to investigate the effects of liquiritin (LQ), the main bioactive compound in licorice against acute lung injury (ALI) and explore the potential mechanism. Methods: Lipopolysaccharide (LPS) was used to induce inflammation in RAW264.7 cells and zebrafish. Intratracheal instillation of 3 mg/kg of LPS was used for induction an ALI mice model. The concentrations of IL-6 and TNF-α were tested using the enzyme linked immunosorbent assay. Western blot analysis was used to detect the expression of JNK/Nur77/c-Jun related proteins. Protein levels in bronchoalveolar lavage fluid (BALF) was measured by BCA protein assay. The effect of JNK on Nur77 transcriptional activity was determined by luciferase reporter assay, while electrophoretic mobility shift assay was used to examine the c-Jun DNA binding activity. Results: LQ has significant anti-inflammatory effects in zebrafish and RAW264.7 cells. LQ inhibited the expression levels of p-JNK (Thr183/Tyr185), p-Nur77 (Ser351) and p-c-Jun (Ser63), while elevated the Nur77 expression level. Inhibition of JNK by a specific inhibitor or small interfering RNA enhanced the regulatory effect of LQ on Nur77/c-Jun, while JNK agonist abrogated LQ-mediated effects. Moreover, Nur77-luciferase reporter activity was suppressed after JNK overexpression. The effects of LQ on the expression level of c-Jun and the binding activity of c-Jun with DNA were attenuated after Nur77 siRNA treatment. LQ significantly ameliorated LPS-induced ALI with the reduction of lung water content and BALF protein content, the downregulation of TNF-α and IL-6 levels in lung BALF and the suppression of JNK/Nur77/c-Jun signaling, which can be reversed by a specific JNK agonist. Conclusion: Our results indicated that LQ exerts significant protective effects against LPS-induced inflammation both in vivo and in vitro via suppressing the activation of JNK, and consequently inhibiting the Nur77/c-Jun signaling pathway. Our study suggests that LQ may be a potential therapeutic candidate for ALI and inflammatory disorders. [ABSTRACT FROM AUTHOR]

We described the fabrication and testing of a multi-plasma-jet triggered gas switch(MPJTGS). The MPTJGS consists of two high-voltage electrodes and a trigger electrode, in which a novel six-channel annular microplasma gun is embedded to generate multichannel plasma jets as seed electron sources when a nanosecond trigger pulse arrives. The multiple discharge channels were induced by the multichannel plasma jets. We investigated the multichannel discharge performance of the MPJTGS in two working modes with charging voltage of ±25 kV, trigger voltage of +40 kV (25-ns rise time), and trigger energy of 2, 32, and 240 J at different working coefficients. Results showed that the average number of discharge channels increased as the trigger energy increased, and decreased as the working coefficient decreased. The MPJTGS operated in Mode II had better multichannel discharge characteristics than in Mode I at the same condition. At trigger energy of 240 J and working coefficient of 87.1%, the average number of discharge channels could reach 7 in Mode II. [ABSTRACT FROM PUBLISHER]

Reducing the working coefficient of gas switch can effectively lower the prefires probability. This paper discusses in detail the discharge characteristics of a three-electrode plasma-jet triggered gas switch (PJTGS), especially at low working coefficients. The triggered discharge process of the PJTGS is analyzed. Plasma jets are observed and discussed with respect to trigger voltage, trigger energy, and gas pressure. In addition, the switch jitters at different conditions are investigated, including ground resistor, charging voltage, trigger energy, trigger voltage, and working coefficient. The results indicate that the height of the plasma jet increases with the increase of trigger voltage and energy, and decreases with the increase of gas pressure. At working coefficients higher than 75%, trigger voltage of +80 kV, and ground resistor of 100 \(\Omega \) , reliable subnanosecond jitters can be obtained with the charging voltages of ±25, ±30, ±40, and ±50 kV. When the working coefficients are between 50% and 28.1%, the switch jitters range from 1.6 to 3.5 ns. Even at the working coefficient of 28.1%, the PJTGS can still be triggered reliably with a switch jitter of 3.5 ns. [ABSTRACT FROM AUTHOR]

• Expand the application of singularity functions for cable configuration. • Provide the mathematical derivation defining the cable deflection and forces when subject to point loads. • Define the procedure to employ the developed method for determining cable configuration during varied construction stages. • Provide an example of determining cable configuration by using developed method when main span cable is subject to point loads from suspenders. This paper presents a solution procedure for cable configurations, such as the ones used for suspension and cable stayed bridges. It employs a semi analytical method with direct integration of singularity functions. The procedure is rigorous and more efficient than other solution techniques for this class of structures. It can include any number of discontinuous and continuous loads and can take into account the initial configuration of the cable. Because of its efficiency the solution process compared to other solution methods such as finite element analysis is suitable for parametric studies that are needed during the design and construction processes. The procedure may also be used for developing a macro element of cable and its suspenders for use in an efficient finite element solution. [ABSTRACT FROM AUTHOR]

High-frequency (HF) signal injection methods have proved to be good candidates for permanent magnet synchronous motor sensorless control at zero or low speed. However, conventional methods have some shortcomings, and several improved methods have been put forward by scholars. In order to analyze the essential relationships among these methods, a unified graphical model is proposed in this paper based on the analysis of mechanism of conventional HF signal injection methods. According to the unified graphical model, the signal modulation modes can be categorized into phase-modulated-based HF injection (PMHI) and amplitude-modulated-based HF injection (AMHI), meanwhile the demodulation modes can be classified into open-loop calculation and close-loop convergence. Besides, novel methods are easily deduced from the unified graphical model. Furthermore, the effects of adverse factors, including resistance, digital control delay, inverter nonlinearity, and cross saturation on PMHI and AMHI are analyzed, respectively. Finally, experimental results prove the validity of the theoretical analysis. [ABSTRACT FROM AUTHOR]

In this paper, a novel six-channels annular plasma-jet chamber is designed and embedded in the trigger electrode of the three-electrode gas switch to generate multichannel plasma jets without air flow, which is used to trigger the gas switch to form multichannel discharge. Results of this paper show that the plasma-jet triggering can be conductive to steady formation of multichannel discharge. [ABSTRACT FROM PUBLISHER]

The unstable change of early temperature field during concrete curing of box girder could lead to the thermal deformation and autogenous shrinkage deformation of concrete, make the concrete crack early, and even affect the subsequent mechanical performance. In order to study the variation law of the early-age temperature field of the box girder concrete and to seek the method to control the variation of the temperature field of the box girder concrete, the No.0 box segment with the most complex structure and the largest volume in the bridge was selected as the research object. The early-age temperature field of No.0 box segment after pouring was simulated by Midas/FEA and the correctness of the simulation was verified by field measurement. Then the time-history law of early-age temperature field of the box girder under the coupling effect of hydration heat and ambient temperature was studied, and the time-history law of the early-age temperature field of the box girder was investigated by changing different concrete curing parameters. The results show that the larger the local size is, the larger the temperature difference is. The selection of formwork's material and thickness should integrate the factors of formwork bearing capacity and thermal insulation performance. The reasonable selection of formwork can effectively control the core temperature and the temperature difference between the inside and outside of the box girder. Formwork installation temperature and wind velocity have a great influence on the temperature difference between the inside and outside of the box girder. The research results can provide technical support for controlling the early-age temperature field changes of box girder concrete, be used to provide a theoretical basis for the best selection of formwork and the selection of the best concrete curing conditions, and help to improve efficiencies in the uses of human capital, energy, and building materials in engineering construction. [ABSTRACT FROM AUTHOR]