Refiector Deformation Measurement and Correction Methodology of Large Antenna Based on Phased Array Feed

To solve the problem of time-consuming measurement and correction of large antennas’reflector deformation,a new microwave holography methodology based on a Phased Array Feed(PAF)is proposed.Starting from the known expression of receiving signals in microwave holography,the theory of PAF holography is derived through Geometrical Optics.Reflector deformation,as well as pointing deviation and subreflector offset,can be calculated out by applying the derived equations.A measurement and correction system based on PAF holography is depicted,and two kinds of measurement methods are illustrated.The proposed measurement methodology is verified by numerical simulation,and its measurement error is analyzed.The results indicate that our proposed methodology is feasible,especially for Cassegrain antennas.

A New Method of Frequency Fluctuation Estimation and IPS Processing Results Based on the Downlink Signal of Tianwen-1

The radio-occultation observations taken by Tianwen-1 are aiming to study the properties of solar wind.A new method of frequency fluctuation(FF)estimation is presented for processing the down-link signals of Tianwen-1 during the occultation period to study the properties of the coronal plasma at the heliocentric distances of 4.48–19 R_(⊙).Because of low S/N as well as the phase fluctuation phenomena caused by solar activity,a Kalman based on polynomial prediction methods is proposed to avoid the phase locked loop loss lock.A new detrend method based on multi-level iteration correction is proposed to estimate Doppler shift to get more accurate power density spectra of FF in the low frequency region.The data analyze procedure is used to get the properties of the solar corona during the occultation.The method was finally verified at the point when the solar offset is 5.7 R_(⊙),frequency tracking was successfully performed on data with a carrier-to-noise ratio of about 28 dBHz.The density spectra obtained by the improved method are basically the same when the frequency is greater than 2 mHz,the uncertainty in the result of the rms of the FF obtained by removing the trend term with different order polynomials is less than 3.3%.The data without eliminating interference show a large error for different detrending orders,which justifies the need for an improved approach.Finally,the frequency fluctuation results combined with the information on intensity fluctuation obtained by the new method are compared with the results of the integrated Space Weather Analysis system and theoretical formula,which verifies that the processing results in this paper have a certain degree of credibility.

急性结肠憩室炎132例临床特点分析

目的探讨急性结肠憩室炎的临床特点.方法回顾性分析2007年1月-2017年12月该院收治的资料完整且经腹部CT、结肠镜和/或手术确诊的急性结肠憩室炎132例患者的临床资料.结果男89例,女43例,男女比例为2.1:1.0,发病年龄(51.8±13.1)岁;急性单纯性结肠憩室炎119例(90.2%),急性复杂性结肠憩室炎13例(9.8%);发病部位:盲肠升结肠82例(62.1%),乙状结肠23例(17.4%),降结肠16例(12.1%),横结肠8例(6.1%),同时累及两个部位者3例(2.3%);主要症状:腹痛132例(100.0%),发热117例(88.6%),腹部压痛132例(100.0%);外周血白细胞计数(WBC)升高者103例(78.0%),WBC计数(15.8±5.1)×109/L,C反应蛋白(CRP)升高者124例(93.9%),CRP数值(34.1±15.3)mg/L;所有患者均行腹部CT检查,有结肠壁增厚表现者124例(93.9%),结肠周围脂肪组织密度增高者78例(59.1%);119例急性单纯性憩室炎患者均经静脉输注抗生素后好转,13例急性复杂性憩室炎患者中,3例经单纯静脉输注抗生素后好转,5例单纯腹腔脓肿和2例腹腔脓肿伴腹腔积液者静脉输注抗生素,同时行腹腔引流管引流后好转,2例腹腔游离气体及1例腹腔脓肿并瘘管形成、腹腔积液患者行开腹手术治疗后好转,在院期间无死亡病例.结论急性结肠憩室炎好发于中老年男性,常见临床表现为腹痛、发热、腹部压痛,腹部增强CT在其诊断及病情评估中起重要作用,大部分患者无并发症,预后良好.

Ground experiments and performance evaluation of the Low-Frequency Radio Spectrometer onboard the lander of Chang’e-4 mission

The Low-Frequency Radio Spectrometer(LFRS)is a scientific payload onboard the Chang’e-4 lunar lander launched in December 2018.The LFRS provides in-situ measurements of the low-frequency radio phenomena on the far-side of theMoon for the first time in human history.To evaluate the performance of the LFRS,a series of ground experiments are conducted using an engineering model of the LFRS.It is not easy to perform the experiments because the Electro Magnetic Interference(EMI)from the Chang’e-4 lunar lander itself and the environment is very intense.The results after EMI mitigation show that the sensitivity of the LFRS may be 10^(−18)W m^(−2)Hz^(−1).

A Wideband Microwave Holography Methodology for Reflector Surface Measurement of Large Radio Telescopes

Most reflector surface holographic measurements of a large radio telescope utilize a geostationary satellite as the signal source. The shortcoming is that those measurements could only be done at a limited elevation angle due to the satellite’s relatively stationary state. This paper proposed a new wideband microwave holographic measurement method based on radio sources to achieve full-elevation-angle measurement with small size reference antenna. In theoretical derivation, the time delay and phase change due to path length and device difference between the antenna under test and reference antenna are compensated first. Then the correct method of wideband holography effect, which is because of antenna pattern differing under different wavelengths when receiving a wideband signal, is presented. To verify the proposed methodology, a wideband microwave holographic measurement system is established, the data processing procedure is illustrated, and the reflector surface measurement experiments on a 40 m radio telescope at different elevation angles are conducted. The result shows that the primary reflector surface root-mean-square at around elevation angles of 28°, 44°, 49°, and 75° are respectively 0.213 mm, 0.170 mm, 0.188 mm, and 0.199 mm. It is basically consistent with the real data, indicating that the proposed wideband microwave holography methodology is feasible.

The New Wuqing 70 m Radio Telescope and Measurements of Main Electronic Properties in the X-band

The new Wuqing 70 m radio telescope is first used for the downlink data reception in the first Mars exploration mission of China,and will be used for the other deep space communications and radio astronomical observations in the future.The main specifications and measurement results of some properties in the X-band are introduced in this paper,such as pointing calibration,gain and efficiency,system noise temperature,system equivalent flux density,and variations with elevation.The 23 parameters pointing calibration model considering the atmospheric refraction correction in real time is presented in the telescope,and the pointing accuracy reaches 570 in azimuth direction and 607 in elevation direction for different weather conditions.More than 62%efficiencies are achieved at full elevation range,and more than 70%in the mid-elevation.The system equivalent flux density of the X-band in the mid-elevation reaches 26 Jy.

IPS observation system for the Miyun 50m radio telescope and its commissioning observation

Ground-based observation of Interplanetary Scintillation （IPS） is an impor- tant approach for monitoring solar wind. A ground-based IPS observation system has been newly implemented on a 50 m radio telescope at Miyun station, managed by the National Astronomical Observatories, Chinese Academy of Sciences. This observa- tion system has been constructed for the purpose of observing solar wind speed and the associated scintillation index by using the normalized cross-spectrum of a simul- taneous dual-frequency IPS measurement. The system consists of a universal dual- frequency front-end and a dual-channel multi-function back-end specially designed for IPS. After careful calibration and testing, IPS observations on source 3C 273B and 3C 279 have been successfully carried out. The preliminary observation results show that this newly-developed observation system is capable of performing IPS observa- tion. The system＇s sensitivity for IPS observation can reach over 0.3 Jy in terms of an IPS polarization correlator with 4 MHz bandwidth and 2 s integration time.

Catalpol ameliorates LPS-induced endometritis by inhibiting inflammation and TLR4/NF-κB signaling

Catalpol is the main active ingredient of an extract from Radix rehmanniae,which in a previous study showed a protective effect against various types of tissue injury.However,a protective effect of catalpol on uterine inflammation has not been reported.In this study,to investigate the protective mechanism of catalpol on lipopolysaccharide(LPS)-induced bovine endometrial epithelial cells(bEECs)and mouse endometritis,in vitro and in vivo inflammation models were established.The Toll-like receptor 4(TLR4)/nuclear factor-κB(NF-κB)signaling pathway and its downstream inflammatory factors were detected by enzyme-linked immunosorbent assay(ELISA),quantitative real-time polymerase chain reaction(qRT-PCR),western blot(WB),and immunofluorescence techniques.The results from ELISA and qRT-PCR showed that catalpol dose-dependently reduced the expression of pro-inflammatory cytokines such as tumor necrosis factorα(TNF-α),interleukin(IL)-1β,and IL-6,and chemokines such as C-X-C motif chemokine ligand 8(CXCL8)and CXCL5,both in bEECs and in uterine tissue.From the experimental results of WB,qRT-PCR,and immunofluorescence,the expression of TLR4 and the phosphorylation of NF-κB p65 were markedly inhibited by catalpol compared with the LPS group.The inflammatory damage to the mouse uterus caused by LPS was greatly reduced and was accompanied by a decline in myeloperoxidase(MPO)activity.The results of this study suggest that catalpol can exert an anti-inflammatory impact on LPS-induced bEECs and mouse endometritis by inhibiting inflammation and activation of the TLR4/NF-κB signaling pathway.

Erratum to: Catalpol ameliorates LPS-induced endometritis by inhibiting inflammation and TLR4/NF-κB signaling

Erratum to:J Zhejiang Univ-Sci B(Biomed&Biotechnol)201920(10):816-827 https://doi.org/10.1631/jzus.B1900071The original version of this article unfortunately contained a mistake.In p.823,Figs.8 c and 8 d were incorrect,and the obvious pathological changes were mistakenly placed in the picture.