中国农业气象观测业务的发展及未来展望

农业气象观测是农业现代化发展的重要基石。本研究全面梳理了中国农业气象观测发展历程、业务服务现状和存在的问题,探讨了未来中国农业气象观测业务服务的发展趋势,以期为护航现代化农业可持续发展和国家粮食安全提供参考。中国农业气象观测业务发展大致经历了理论探索、机构组建、试点建设、形成规模、优化调整和稳定快速发展六个阶段。目前全国已经建立了以653个农业气象观测站(含70个农业气象试验站)为基础的观测站网体系,开展作物、土壤水分、自然物候、畜牧、果树、林木、蔬菜和农业小气候等的观测与研究;在观测业务发展的基础上,构建了结构科学、功能先进的国家、省、市、县四级农业气象业务服务体系,全国农业气象监测评价、作物产量预报、农业气象灾害监测评估与影响预报、农用天气预报、农林病虫害发生发展气象等级预报、农田墒情、抗旱救灾及生态气象监测与预测预报等的业务服务技术已较为成熟,服务成效显著。随着全国农业产业布局优化、种植结构和种植方式调整,以及自动观测技术和设备的迅猛发展,农业气象观测业务服务逐渐显现出观测站网布局不够合理、观测规范不能满足需求、观测技术和观测设备自动化不足、业务服务精细化多元化程度不够等问题。从对农业气象观测业务发展战略部署、农业气象观测高质量发展目标以及现代农业发展对农业气象服务需求的角度来看,未来中国农业气象观测业务需形成观测站网布局和观测任务科学合理、业务质量管理体系健全、现代化观测体系完善、业务服务多元精细,以及与国际接轨的现代化农业气象观测业务服务体系。

Review on Dynamic Modeling and Vibration Characteristics of Rotating Cracked Blades

As one of the most important parts in the engine,the structure and state of the rotating blade directly affect the normal performance of the aeroengine.In order to monitor engine crack failure and ensure flight safety,it is necessary to carry out research on the dynamic modeling of the cracked blade and breathing crack-induced vibration mechanisms.This paper summarizes the current research status on the dynamics of cracked blade,and the related topics mainly include four aspects:crack propagation path,mechanical model of open and breathing cracks,dynamic modeling methods of cracked blades such as lumped mass model,semi-analytical model and finite element model,and dynamic characteristics of cracked blades.The review will provide valuable references for future studies on dynamics and fault diagnosis of cracked blade in aeroengine.

FABP4 secreted by M1-polarized macrophages promotes synovitis and angiogenesis to exacerbate rheumatoid arthritis

Increasing evidence shows that adipokines play a vital role in the development of rheumatoid arthritis(RA).Fatty acid-binding protein 4(FABP4),a novel adipokine that regulates inflammation and angiogenesis,has been extensively studied in a variety of organs and diseases.However,the effect of FABP4 on RA remains unclear.Here,we found that FABP4 expression was upregulated in synovial M1-polarized macrophages in RA.The increase in FABP4 promoted synovitis,angiogenesis,and cartilage degradation to exacerbate RA progression in vivo and in vitro,whereas BMS309403(a FABP4 inhibitor)and anagliptin(dipeptidyl peptidase 4 inhibitor)inhibited FABP4 expression in serum and synovial M1-polarized macrophages in mice to alleviate RA progression.Further studies showed that constitutive activation of mammalian target of rapamycin complex 1(mTORC1)by TSC1 deletion specifically in the myeloid lineage regulated FABP4 expression in macrophages to exacerbate RA progression in mice.In contrast,inhibition of mTORC1 by ras homolog enriched in brain(Rheb1)disruption specifically in the myeloid lineage reduced FABP4 expression in macrophages to attenuate RA development in mice.Our findings established an essential role of FABP4 that is secreted by M1-polarized macrophages in synovitis,angiogenesis,and cartilage degradation in RA.BMS309403 and anagliptin inhibited FABP4 expression in synovial M1-polarized macrophages to alleviate RA development.Hence,FABP4 may represent a potential target for RA therapy.

不同临床设计的ERA附着体义齿修复下颌牙列游离端缺损的三维有限元分析

目的:研究3种不同临床设计ERA附着体义齿修复下颌远中游离端缺损的应力及位移分布。方法:建立ERA附着体义齿修复下颌远中游离端缺损的三维有限元模型,根据临床设计分为基本组、支托组和跨弓组。应用有限元法研究在垂直及45°斜向2种载荷方向100 N的作用下,基牙及基托下黏膜的应力和位移以及基托的位移情况。结果:2种载荷下3组模型均在远中基牙远中邻面肩台出现应力集中,远中基牙预备体咬合面位移最大,支托组基牙位移最大,分别为14.91μm和63.09μ.m,其次为基本组(9.38μm和50.56μm),跨弓组最小(8.85μm和47.31μm)。结论:在本研究条件下,为远中游离端牙列缺损设计基本的ERA附着体义齿更趋于合理。

High-performance RF Switch in 0.13 μm RF SOI process

A high-performance single-pole single-throw(SPST) RF switch for mobile phone RF front-end modules(FEMs) was designed and characterized in a 0.13 μm partially depleted silicon-on-insulator(PD SOI) process. In this paper, the traditional seriesshunt configuration design was improved by introducing a suitably large DC bias resistor and leakage-preventing PMOS, together with the floating body technique. The performance of the RF switch is greatly improved. Furthermore, a new Ron × Coff testing method is also proposed. The size of this SPST RF switch is 0.2 mm2. This switch can be widely used for present 4 G and forthcoming 5 G mobile phone FEMs.

Comparative Analysis of Internal and External-Hex Crown Connection Systems - A Finite Element Study

The abutment connection with the crown is fundamental to the structural stability of the implant system and to the prevention of mechanical exertion that can compromise the success of the implant treatment. The aim of this study is to clarify the difference in the stress distribution patterns between implants with internal and external-hex connections with the crown using the Finite Element Method (FEM). Material and Methods: The internal and external-hex connections of the Neoss and 3i implant systems respectively, are considered. The geometrical properties of the implant systems are modeled using three-dimensional (3D) brick elements. Loading conditions include a masticatory force of 200, 500 and 1000N applied to the occlusal surface of the crown along with an abutment screw torque of 110, 320 and 550Nmm. The von Mises stress distributions in the crown are examined for all loading conditions. Assumptions made in the modeling include: 1. half of the implant system is modeled and symmetrical boundary conditions applied;2. temperature sensitive elements are used to replicate the torque within the abutment screw. Results: The connection type strongly influences the resulting stress characteristics within the crown. The magnitude of stress produced by the internal-hex implant system is generally lower than that of the external-hex system. The internal-hex system held an advantage by including the use of an abutment between the abutment screw and the crown. Conclusions: The geometrical design of the external-hex system tends to induce stress concentrations in the crown at a distance of 2.89mm from the apex. At this location the torque applied to the abutment screw also affects the stresses, so that the compressive stresses on the right hand side of the crown are increased. The internal-hex system has reduced stress concentrations in the crown. However, because the torque is transferred through the abutment screw to the abutment contact, changing the torque has greater effect on this hex system than the masticatory force. Overall the masticatory force is more influential on the stress within the crown for the external-hex system and the torque is more influential on the internal-hex system.

PDZK1 protects against mechanical overload-induced chondrocyte senescence and osteoarthritis by targeting mitochondrial function

Mechanical overloading and aging are two essential factors for osteoarthritis(OA)development.Mitochondria have been identified as a mechano-transducer situated between extracellular mechanical signals and chondrocyte biology,but their roles and the associated mechanisms in mechanical stress-associated chondrocyte senescence and OA have not been elucidated.

基于多源信息的遥感综合干旱监测模型

为解决传统遥感干旱指数侧重于对单一响应因子的监测,缺乏对干旱综合评估的问题,本文结合气象观测资料和多源遥感数据,择优选择TVDI、RVI、PDI和GVMI日产品数据作为自变量,与卫星过境相邻时刻气象观测资料计算的MCI指数为因变量,采用随机森林回归算法(Random Forest Regression,RFR)构建综合遥感干旱监测模型。结果表明:与传统最小二乘法模型(Ordinary Least Squares,OLS)相比,RFR模型训练集和测试集精度均优于OLS模型。RFR训练集R值为0.97,RMSE为0.33,测试集R值为0.90,RMSE为0.53;OLS模型训练集R值为0.78,RMSE值为0.73,测试R值为0.76,RMSE值为0.79,表明RFR模型在表征区域旱情时比OLS模型更加优秀。在2022年西南地区旱情监测评估中,RFR遥感干旱监测结果与MCI指数时空分布较为一致,能较好地表征区域旱情的时空动态变化特征,体现了RFR模型在实际干旱监测过程中的实用性。但RFR干旱监测精度与区域站点个数和站点空间分布有关,在站点个数较多,站点分布均匀的区域,RFR干旱监测模型精度较高。

往返式平漂探空下降段FY-3D卫星湿度廓线检验

往返式平漂探空观测(以下简称平漂探空)可实现地面至平流层低层大气温度廓线垂直探测以及平流层低层内持续4 h水平温度分布探测。目前,平漂探空已在长江中下游、广东、内蒙古等多地开展观测试验,效果良好。利用2021年3—9月长江中下游平漂探空试验数据完成对卫星反演大气湿度廓线数据的检验,结果显示:由平漂探空下降段数据的检验结果可知,卫星湿度廓线的平均绝对误差约15%,均方根误差约20%。在午间、夜间,卫星反演的湿度廓线数据质量比清晨、傍晚的湿度廓线相对较好。卫星反演的湿度平均绝对误差和均方根误差随海拔升高而减小,随湿度增大而增大。在湿度50%以下,卫星反演的湿度偏大;在湿度50%以上,卫星反演的湿度偏小。

A preliminary analysis and discussion of the condominium building collapse in surfside,Florida,US,June 24,2021

On June 24,2021,a 40-year-old reinforced concrete flat plate structure building in Miami suffered a sudden partial collapse.This study analyzed the overall performance and key components of the collapsed building based on the building design codes(ACI-318 and GB 50010).Punching shear and post-punching performances of typical slabcolumn joints are also studied through the refined finite element analysis.The collapse process was simulated and visualized using a physics engine.By way of these analyses,weak design points of the collapsed building are highlighted.The differences between the reinforcement detailing of the collapsed building and the requirements of the current Chinese code are discussed,together with a comparison of the punching shear and post-punching performances.The simulated collapse procedure and debris distribution are compared with the actual collapse scenes.

Improving Multi-Model Ensemble Forecasts of Tropical Cyclone Intensity Using Bayesian Model Averaging

This paper proposes a method for multi-model ensemble forecasting based on Bayesian model averaging （BMA）, aiming to improve the accuracy of tropical cyclone （TC） intensity forecasts, especially forecasts of minimum surface pressure at the cyclone center （Pmin）＇ The multi-model ensemble comprises three operational forecast models： the Global Forecast System （GFS） of NCEP, the Hurricane Weather Research and Forecasting （HWRF） models of NCEP, and the Integrated Forecasting System （IFS） of ECMWF. The mean of a predictive distribution is taken as the BMA forecast. In this investigation, bias correction of the minimum surface pressure was applied at each forecast lead time, and the distribution （or probability density function, PDF） of emin was used and transformed. Based on summer season forecasts for three years, we found that the intensity errors in TC forecast from the three models var-ied significantly. The HWRF had a much smaller intensity error for short lead-time forecasts. To demonstrate the proposed methodology, cross validation was implemented to ensure more efficient use of the sample data and more reliable testing. Comparative analysis shows that BMA for this three-model ensemble, after bias correction and distri-bution transformation, provided more accurate forecasts than did the best of the ensemble members （HWRF）, with a 5%-7% decrease in root-mean-square error on average. BMA also outperformed the multi-model ensemble, and it produced ＂predictive variance＂ that represented the forecast uncertainty of the member models. In a word, the BMA method used in the multi-model ensemble forecasting was successful in TC intensity forecasts, and it has the poten-tial to be applied to routine operational forecasting.