天旋、岁差与中西之争——清代科学思想史的一条线索

明清之际西方岁差的"恒星东移"解释传入中国,引爆了激烈的中西论争。梅文鼎通过对历算史的重构将"恒星东移"纳入中法范式,但分歧并未就此消弭。安清翘通过解构西学、回归中学,将"恒星东移"从中学体系剔除出去,同时对"西学中源说"提出了系统性的批评。令人深思的是,梅文鼎倡导"西学中源说"是以默认西学优于中学为隐含前提,安清翘批评"西学中源说"则以否定西学优于中学为预设基础,立论虽然不同,但目标却出奇的一致,即发扬传统以求超胜!就中学的维护和弘扬而言,"西学中源"的解构者安清翘甚至比倡导者梅文鼎更坚决、更彻底。岁差与中西之争的表象之下,隐含着当时受到西学影响而升华的中国传统天旋模式之争这一深刻背景。三者复杂纠缠、整体联动,刻画出有清一代科学思想史的一条清晰而重要的线索。

《荀子·天论》“列星随旋日月递炤”天文学涵义研究

荀子是孔子儒学思想的重要传承者。通过结合天文史学、文献史料和古文字学资料集中探讨荀子在所著《天论》一章中所体现的天文学思想。我们认为,荀子在中国古代天旋说的探讨过程中持右旋说观点,并对董仲舒、班固等人产生了深刻影响。

用于势场反演的特殊解法

本文以无旋场的积分路径为射线，以边界上已知的势值为输入、输出量，利用反拉东变换求一个梯度场的势函数，用反演的方法求解可以化为拉普拉斯方程的一类二阶偏微分方程。其思路新颖，原理独特，运算正确，边界条件处理方便，数值实现容易。在重力场和地电场的研究中可能得到应用。

The development of a powerful Mongolian cyclone on 14-15 March 2021:Eddy energy analysis

Intense and extensive dust,caused by a strong Mongolian cyclone,hit Mongolia and northern China on 14-15 March 2021.In this study,the development process of this cyclone is analysed from the perspective of highfrequency eddy energetics.During the low-frequency circulation field of early March of 2021,an amplified polar vortex intruding towards central Asia and a ridge straddling eastern and northeastern Asia worked in concert to comprise a strong baroclinic zone from central Asia to Lake Baikal.Under these favourable conditions,on 13 March,a migratory trough triggered the Mongolian cyclone by crossing over the Sayan Mountains.The downwards transfer of kinetic energy from the eddy at 850 hPa played a key role in the intensification and mature stage of the cyclone.This mechanism was primarily completed by the cold air sinking behind the cold front.The frontal cyclone wave mechanism became crucial once the cyclone started to rapidly develop.The authors emphasize that the anomalously large growth of high-frequency available potential energy,which characterized this super strong cyclone,was obtained by extracting energy first from the time-mean available potential energy and then from the low-frequency available potential energy.The interannual temperature anomaly pattern of"north cold south warm"facilitated the additional time-mean available potential energy,and the temperature anomaly pattern of"northwest cold southeast warm"conditioned the extra low-frequency available potential energy.The analysis results suggest that the interaction between high-and low-frequency waves was also important in the development of the intense cyclone.

STUDY ON A NOVEL ELLIPSOIDAL HELICAL ANTENNA

A novel ellipsoidal helical antenna is proposed and studied in this letter. As a special in-stance,the hemispherical helical antennas are analyzed firstly,which indicates that the characteristics of a two-arm unit are better than that of a single-arm unit. Based on this,the ellipsoidal helical antenna,formed by changing the axial direction’s dimension of the two-arm hemispherical helical antenna,is analyzed by the moment method with curved basic and testing function. The effects to VSWR (Voltage Standing Wave Ratio),gain,polarization and patterns by the axial direction’s dimensions are inves-tigated. The study results provide dependable gist to the choice of antenna format according to the practical requirements.

ENSEMBLE PREDICTION EXPERIMENTS OF TRACKS OF TROPICAL CYCLONES BY USING MULTIPLE CUMULUS PARAMETERIZATION SCHEMES

Ensemble prediction experiments of the tracks of eight tropical cyclones occurring between 2004-2006 over the western Pacific have been performed by using MM5 with five cumulus parameterization schemes. The results show that the predictions of the tracks of the tropical cyclones are sensitive to the selection of cumulus parameterization schemes. Each scheme has its own advantage and disadvantage, and the predications without cumulus parameterization schemes are not the worst, sometimes even better than the others. And all of the three ensemble methods improve the predictions of the tracks significantly, among which the ensemble method without parameterization schemes, the Grell, Betts-Miller and Kain-Fritsch schemes are the best.

略谈历代注家对左还右还的理解

我们平常将顺时针方向的转动叫做右转，或者说往右转。不过，时针过十二点的时候固然是往右走，但过三点时往下走，过六点时则是往左转动的。应该说我们对右转、左转的方向概念只是约定俗成的一种习惯，并不是绝对的。实际上，在中国古代，虽然不免有些混乱，但一般的观念都认为右转、右旋意味着反时针方向的转动，跟现在正相反。以下介绍古籍中有关左旋、右旋的记载，并且讨论历代学者对左旋、右旋方向的理解。

NUMERICAL SIMULATIONS OF β-GYRES IN TROPICAL CYCLONES

The circulation of β-gyres in tropical cyclones is studied using numerical simulations. As shown in the result, there is clear circulation of β-gyres in the deviation flow field of the middle layer of the model,i.e. there is cyclone current west of the vortex center but anticyclone current east of it. The theory analysis shows that the circulation of β-gyres is formed by the advection of geostrophic vorticity.

Current status and challenges of typhoon forecasting and warning systems in China

China is one of the countries most severely suffering from tropical cyclones. The exact and timely forecasting and warning is of significant importance in fighting against tropical cyclones and mitigating their impacts on China. The numerical weather prediction （NWP） system for tropical cyclone rainfall and strong wind is going to play a more and more important role. There is also a need for timely and user friendly modem warning services in order to provide the governments and relevant authorities at all levels and general public with typhoon forecasts and information about the associated disasters and response strategy services.

AN OBJECTIVE PREDICTION SCHEME FOR TROPICAL CYCLONES MAKING LANDFALLS IN EASTERN CHINA

The landfall of tropical cyclones in the eastern part of China falls in the category of small probability events. Constructing a step function with intervals adequately divided can help reflect the non-linear distribution of conditional probability for a landfall event. For the prediction of landfall event probability, factors applying the step function in transformation are superior to the standardized factors that are linearly related. The prediction scheme discussed in the work uses transformation factors of step function to formulate prediction models for tropical cyclones making landfalls in eastern China, through screening with non-linear correlative ratios and REEP analysis. Classified models for statistic-synoptics, statistic-climatology and statistic-dynamics have been constructed using initial field data and numerical prediction output. Forecasting skills have been improved due to ensemble of predictions using these classified models. As shown in forecasting evaluations and experiments, the scheme is capable of predicting tropical cyclones that make landfalls in eastern China.

Design and optimization of a cavity-backed spiral antenna for use in 6-12 GHz band

The design and optimization of a self-complementary two-arm Archimedean spiral antenna backed by an absorptive cavity were presented. Parametric studies on the proposed antenna structure were carried out by using CST MWS. Simulation results show that the proper choice of spiral turns and cavity depth can miniaturize the dimensions of the cavity-backed spiral antenna presented here. According to simulation results, prototype antennas operating in the 6 12 GHz band are fabricated and the dimension of the proposed cavity-backed spiral antenna is 22 mm (diameter)×15 mm (height). The performance of the proposed antenna was measured and compared with the simulation results. It is shown that the experimental results are consistent with the theoretical predictions and the suggested antenna is good enough to adapt for various wideband applications.

Astronomical forcing of sedimentary cycles of Late Eocene Liushagang Formation in the Bailian Sag, Fushan Depression, Beibuwan Basin, South China Sea

Sediments in the Liushagang Formation of Late Eocene form a group of key hydrocarbon play fairways in the Beibuwan Basin,South China Sea.As an important reservoir-forming combination,the Liushagang Formation consists of deltaic siliciclastic and show clear sedimentary cyclicity.According to paleontology research and stratigraphic correlation,the boundary between Liushagang Formation(Els)and Weizhou Formation(Ewz)is regarded as the Eocene-Oligocene boundary.The oxygen isotope dating for well cores from the top of the first Member of Liushagang Formation(Els1)and the bottom of the third Member of Weizhou Formation(Ewz3)give an isochron age of 35.2 Ma.Here,we use GR logging data as a paleoenvironmental proxy to conduct a detailed cyclostratigraphic study of the Els1 in the Bailian Sag,Fushan Depression.Power spectra,evolutionary fast Fourier transformation and wavelet analysis all reveal significant sedimentary cycles in Els1.The ratios of cycle wavelengths in these stratigraphic units are 21?5?2.8?1.2?1,and are interpreted as Milankovitch cycles of 400 ka and 96 ka eccentricity,52 ka obliquity,22ka and 19 ka precession cycles,respectively.An astronomical time scale is established by tuning filtered 96 ka eccentricity cycles to a target curve of Well L2 in the Bailian Sag.Based on regional stratigraphic framework,combined with seismic,cores and logging data,the HST of the first member of the Liushagang Formation(Els1)delta in Well L2 was divided into six parasequence sets named Ps1-Ps6.According to the spectrum analysis by Simple Lomb periodogram from PAST program packages,the sediment accumulation rate of each parasequence sets first increased and then decreased as time went by.The sediment accumulation rate of Ps4 reached the maximum(0.127 m/ka)during the most prosperous period of delta prograding.Finally,the duration of each period of parasequence sets and more accurate geological age were calculated on the basis of sediment accumulation rate.The ages of each depth are precisely estimated and provide new constraints on the Late Eocene.

Comparison study of environmental influences on the intensification of different deep Changjiang-Huaihe cyclones over the East China and Yellow Seas

Abstract： Statistical classification of the intensification of different deepChangiang-Huaihe Cyclones （CHCs） over the East China and Yellow Seas （ECYSs）during 2008 to 2012 is studied using the FNL reanalysis data. Based on the penetrationdepth and the season of occurrence, the CHCs are divided into four categoriesincluding warm-season-deep （WSD）, warm-season-shallow （WSS）, winter-shallow（WTS） and early-spring-bottom （ESB）. Statistics show the CHCs take either aneastward or a northeastward path after entering ECYSs. After moving to the seas, theintensification of CHCs is more significant in cold season than that in warm season.They all have the reduction of the friction of the underlying surface and the increase ofthe near surface winds. The area of strong winds extends and migrates from the east tothe southeast of the CHCs. A significant increase of precipitation during the warmseasons is consistent with the penetration depth of the cyclones. While a slight increaseof precipitation in cold season cyclones and scattered precipitation is observed behindthe ESB cyclones in the early stage of spring. Synthetic diagnosis analysis of the CHCsover ECYSs shows that the latent heat release plays an important role in theamplification of cyclones during the warm season. The ESB cyclones are sensitive tothe dynamic and thermal effects from the underlying surface. The vertical stretching of the positive vorticity volume is much more significant in ESB cyclones than that in othercyclones. The height of maximum upper level divergence is proportional to thepenetration depth of the cyclone for all the categories. Diabatic heating from the underlying surface is more prominent in cold season cyclones. Downward transport ofthe kinetic energy from upper level jet and the reduced friction both have positivecontributions to intensification of the CHCs. Moist Potential Vorticity （MPV） has morecontribution to the intensification of warm season cyclones, especially WSD cyclones.The combined effects from inertial stability and shear stability are beneficial to theamplification of the cyclones in cold season. The position and strength of thetemperature and moisture front from MPV2 term at 1000 hPa coincides with the areaand intensity of precipitation, which shows that the MPV2 is an effective reference forCHCs rainfall forecast.

A Study on the Control of BDSIGPS Self-phase Quadrifilar Helical Antenna for Ship

A reconfigurable, self-phase quadrifilar helical antenna was designed at BDS/GPS frequency band. The impedance, gain and directivity of the antenna were studied by HFSS based on FEM （finite element method） and experiment. Results show the beam width of the main lobe of the pattern can reach over 160° with the help of the load on the top of the antenna. And the power of the side-lobe level is very low. In addition, the quadrifitar helix antenna has excellent right-hand circular polarization performance with a beam width of 180°. Both single-frequency and double-frequency communications can be carried out by the antenna in the ranges between 1.2 and 1.8 GHz, with the bandwidth of each frequency about 60 MHz, the simulating and experimental results are nearly the same.

THE OBJE CTIVE ANALOGUE PREDICTION MODEL FOR TROPICAL CYCLONE TRACK WITH COMPREHENSIVE ASSESSMENT OF THE ENVIRONMENT

An objective analogue prediction model for tropical cyclone (TC) track is put forward that comprehensively assesses the environmental field. With the parameters of the tropical cyclone and environmental field at initial and future time, objective analogue criteria are set up in the model. Analogous samples are recognized by comprehensive assessment to historical TC cases for similarity with multivariate criteria,using non-linear analogue indexes especially defined for the purpose. When the historical tracks are coordinateconverted and weighted with reference to analogue indexes,forecast tracks are determined. As shown in model verification and forecast experiments, the model has forecasting skill.

Malrotation causing duodenal chronic obstruction in an adult

Congenital duodenal obstruction is rare in adulthood. An unusual presentation of this condition has led to difficult preoperative diagnosis.We present a case of proximal jejunal obstruction by a congenital band in an adult and review the literature.

Magnetic Resonance Urography and X-ray Urography Findings of Congenital Megaureter

Objective To observe the imaging findings of congenital megaureter in order to enhance the understanding of this disease. Methods Image data of 5 patients with congenital megaureter and 2 misdiagnosed patients were analyzed, and image findings of congenital megaureter were summarized. Elscint Prestig 2.0T superconductive magnetic resonance urography （MRLI） with conventional sequence （spin-echo, T 1W1560 ms/16 ms; fast spin-echo, T2WI 9600 ms/96 ms） was performed. Raw data were acquired with fast spin-echo sequence from heavy T2-weighted image （9600 ms/120 ms）. Post-processing method of MRH was the maximum in- tensity projection with three-dimensional reconstruction in the workstation. Intravenous pyelography （IVP） was conducted, in which X-ray films were taken 7 minutes, 15 minutes, and 30 minutes after injecting contrast agent, except that in 2 patients the films were taken delayed at 60 and 90 minutes. X-ray retrograde pyelography was performed on 2 patients, successful in one but failed in the other. Results The dilated ureter showed hypointensity on T1-weighted images and hyperintensity on T2-weighted images in conventional MRI. The mass wall was intact, uniform in thickness, and showing hy- pointensity on Tl-weighted and T2-weighted images. The MRH images showed a retroperitoneal mass appearing as an elongated tubular cystic structure spreading from kidney to bladder. MRLI also revealed dilated calices and renal pelvis, pelviureteric obstruction, and renal duplication. The main signs of congenital megaureter in X-urography was significant dilatation of ureter, or normal renal pelvis with ureter dilatation, hydronephrosis, deformity, and displacement. Conclusions MRH with X-urography could visualize the characteristics of congenital megaureter, including the dilation of renal pelvis and ureter, calculi, urinary tract duplication, and stenosis location. The two techniques can complement each other in disease diagnosis and provide more detailed information for preoperative treatment.

Disproportional exaggerated aspartate transaminase is a useful prognostic parameter in late leptospirosis

AIM: To evaluate the hepatic dysfunction in leptospirosis is usually mild and resolved eventually. However,sequential follow-up of liver biochemical data remained lacking..METHODS: The biochemistry data and clinical symptoms of 11 sporadic patients were collected and analyzed, focusing on the impacts of leptospirosis upon liver biochemistry tests.RESULTS: The results disclosed that of the 11 cases, 5 or 45% died. The liver biochemistry data in the beginning of the disease course were only mildly elevated.Nevertheless, late exaggerated aspartate transaminase (AST)elevations were noted in three cases who finally died when compared with the typical course. Besides, significant higher AST/alanine transaminase (ALT) ratios (AARs) of the peak levels for transaminase were also noted in the cases who eventually succumbed. The mean±SD of AARs for the survival group and dead group were 5.65±2.27 (n = 5)and 1.86±0.64 (n = 6) respectively (P= 0.006). The ratios of the cases who finally died were all more than 3.0.Conversely, the survival group's ratios were less than 3.0.CONCLUSION: Serial follow-up of transaminase might provide evidence to predict some rare evolutions in leptospirosis. If AST elevated progressively without a concomitant change of ALT, it might indicate an acute disease course with ensuing death. Additionally, AAR is another prognostic parameter for leptospirosis. Once the value was higher than 3.0, a grave prognosis is inevitable.

COMPARISONS BETWEEN DOPPLER AND SIMULATED FEATURES OF A SUPERCELL

Firstly, typical features of a supercell, which occurred in Guangzhou on August 11, 2004, are discussed by using the new generation weather radar data. V-notch, finger-echo, weak echo region, overfiang and echo-wall are observed from reflectivity products. A vertical cross section of the radial velocity is made along the direction of the low-level inflow and across the maximum reflectivity core, which displays a part of strong updraft and downdraft. Secondly, a 3-D convective storm model is used to simulate the supercell. The maximum reflectivity and the core thickness of the simulated radar echo are 75 dBz and 14km, respectively. These values are more than the counterparts that are detected by radar. The reason is that attenuation is not calculated in the model. The wind field structure is also given when the storm is the strongest. Divergence, caused by thunderstorm outflow, is in the low level. In the middle and high level, convergence is dominant, but the plume is not simulated at the top. Finally, the evolution of the simulated vertical motion is documented. The interaction between the environmental wind and the updraft, which is formed by the convergence on the ground at the beginning, makes the storm stronger. Then, downdraft occurs and grows. When it becomes dominant, the supercell collapses.

CHARACTERISTICS OF TROPICAL CYCLONES ACTIVITIES VARYING WITH ENVIRONMENTAL FIELDS OF MID-AND LOWER-LATITUDES

Using historical data from 1951 to 1996, this paper makes statistical study and elaborate comparisons of tropical cyclone (TC) activity in middle and low latitudes. Some useful results have been achieved. For example, about 65% (90% in May) of the low-latitude tropical cyclones can move north into middle latitudes; TCs in middle latitudes move by about 60 more to the east and 10 km/h faster than in low latitudes; about 60% of the TCs dissipate in middle latitudes; the mean intensity is the maximum near the line dividing the middle and low latitude systems. The work paves the way for more work on revealing characteristics of interactions between middle and low latitude circulation systems.