从科学慈善机构、科学会所到中上阶级的科学学院——英国皇家学院的早期历史研究(1799-1810)

英国皇家学院在创办初期经历了两次大的变动,1802年从面向下层民众的科学慈善机构蜕变为上流社会的科学会所,随即又于1810年转变为面向中上阶级的科学学院。1810年的改革之后,民主的会员制取代了世袭的业主制。自此,皇家学院的体制稳定持续了近两个世纪。大讲堂、图书馆和实验室是皇家学院的主要活动场所,接纳女性听众和开放实验室是皇家学院在当时的两项创举。伦福德伯爵、伯纳德爵士、班克斯爵士和戴维爵士在皇家学院的创办初期发挥了重要作用。戴维推动了皇家学院从科学普及向科学研究与科学普及并重的转变,最终法拉第确立了科学研究与科学普及作为皇家学院的两大主要任务。     

Observational evidences for the speed of the gravity based on the Earth tide

We have found that the current practical Newtonian formula for the gravity tide of the Earth implies a hypothesis that gravity travels at the speed of light; furthermore, we have derived and solved the propagation equation of gravity using the observation data of Earth tides from Shiquanhe and Wushi, after correction of phase lag due to the anelasticity of the Earth, and found that the speeds of gravity are from 0.93 to 1.05 times the speed of light with a relative error of about 5%. This provides first set of strong evidences to show that the speed of gravity is the same as the speed of light.     

Faster than Light Neutrinos

In September, the OPERA experiment in Italy claimed to have observed neutrinos which travel faster than light. Strong experimental constraints are placed by neutrinos observed from the supernova SN1987A and from various terrestrial and astrophysical measurements of synchrotron radiation. I will review the many experimental and theoretical challenges faced by any theory which attempts to explain this result, and speculate on just which theories may succeed.     

农田渍害遥感监测方法研究应用进展

首先介绍了农田渍害的表现特征;其次根据监测原理,将国内外农田溃害遥感监测的主要方法分为地表指示标志法、地下水位反演法和与非遥感方法相结合的综合分析法,并分别对各类方法的原理、技术、适用范围及优缺点进行分析,发现各种方法均能解决特定的农田渍害监测问题,同时也存在着缺陷和局限性;最后,进行了总结并指出了两种潜在的遥感监测方...     

基于主动建模的无人直升机增强LQR控制

为了解决无人直升机控制问题,通过把主动建模与LQR(Linear Quadratic Regulator)控制相结合,提出一种能补偿模型差的控制方法。该方法在悬停状态下,采用简化模型设计LQR控制器,并通过UKF(Un-scented-Kalman-Filter)在线估计简化模型与全状态模型的模型差,使用模型差作为补偿项对LQR控制增强。针对实际直升机动力学模型进行仿真,验证了基于UKF的估计和增强LQR控制的有效性。仿真实验结果证明,基于UKF的主动建模技术能够快速估计状态和参数变化,并且增强LQR控制能够使系统适应模型不确定性。     

Starch grain evidence reveals early pottery function cooking plant foods in North China

Early pottery sherds excavated in northern China date back to more than 11,000 cal a BP, and are presumed to have been used as cooking vessels. There has been, however, no direct evidence to demonstrate this function. Here we report ancient starch grains recovered from carbonized residues adhering to the bases of flat- bottomed vessels excavated from the Zhuannian site dating more than 10,000 cal a BP in the North China Plain. This evidence demonstrates that early pottery was being used to cook cereal grains, particularly millets, and acorns. Because millets were in the process of domestication at thistime, we propose that pottery invention in northern China may have been related to early farming activities.     

A wetness index derived from tree-rings in the Mt. Yishan area of China since 1755 AD and its agricultural implications

Dendroclimatological techniques were employed to investigate the relationship between Chinese Pinus(Pinus tabulaeformis Carr.) growth and climatic variability in the Mt.Yishan region of Shandong Province, China, over the past253 years. Using regression analysis, the wetness index(WI)was reconstructed for the Mt. Yishan area for the period1755–2007 AD based on tree-ring widths; predictor variables accounted for 40 % of the variance. The reconstructed timeseries displayed an increasing trend after the late 1960 s. Both the estimated and the observed WI for May–August were better correlated with precipitation than temperature during the period 1958–2007 AD, indicating that the contribution of precipitation to the WI was larger than temperature in the study area. The reconstructed WI was compared with the dryness/wetness index of China and land areas that were affected by droughts and floods using the agricultural statistics for Shandong Province. In addition, the WI time-series corresponded well with the peanut yield in Shandong Province at high frequency, which may be reasonable in the context of agriculture in Shandong. The 3-, 5- to 6- and 9- to10-year periodicities detected in the time-series suggested that the reconstructed WI in the Mt. Yishan area may be related to large-scale climate variations.     

The nonleptonic two body B decays involving a light tensor meson in final states

The nonleptonic two body Bu,d,s,c decays involving a light tensor meson in final states are studied in the perturbative QCD approach based on kT factorization. The decay modes with a tensor meson emitted, are prohibited in naive factorization, since the emission diagram with a tensor meson produced from vacuum is vanished. While contributions from the so-called hard scattering emission diagrams and annihilation type diagrams are important and calculable in the perturbative QCD approach. The branching ratios of most decays are in the range of 10-4-10-8, which are bigger by 1 or 2 orders of magnitude than the predictions given by the naive factor- ization, but consistent with the predictions from the QCD factorization and the recent experimental measurements. We also give the predictions for the direct CP asymmetries, some of which are large enough for the future experiments to measure. We also find that, even with a small mixing angle, the mixing between f2 and f′2 can bring remarkable changes to both branching ratios and the direct CP asymmetries for some decays involving f2（′） mesons. For decays with a vector meson and a tensor meson in final states, we predict a large percentage of transverse polarization contributions due to the contributions of the orbital angular momentum of the tensor mesons.     

Orbit determination of Chang＇E-3 and positioning of the lander and the rover

Chang＇E-3 landed on the east of Sinus Iridum area on December 14, 2013, performing China＇s first successful soft landing on the lunar surface. We present the results on precision orbit determination and positioning of the lander and the rover. We and methods used to achieve period December 2-21, 2014. describe the data, modeling, position knowledge over the In addition to the radiometric X-band range and Doppler tracking data, delta differential one-way ranging data are also used in the calculation, which show that they strongly improve the accuracy of the orbit reconstruction. Total position overlap differences are about 20 and 30m for the 100km × 100km and 100 kmx 15 km lunar orbit, respectively, increased by ,- 50 % with respect to CE-2 and at the same level as other lunar spacecrafts of recent era such as SELENE and lunar reconnaissance orbiter （LRO）. The position error of the soft landing trajectory is less than 100 m. A kinematic statistical method is applied to determine the position of the lander and relative position of the rover with respect to the lander. The position difference of the lander is better than 50 m compared to LRO photograph result. Compared with the delta very long baseline interferometry （VLBI） group delay between the lander and the rover, the delta VLBI phase delay can improve the relative position of the rover from ～ 1,000 to ～1 m.     

Redox condition during Ediacaran–Cambrian transition in the Lower Yangtze deep water basin,South China: constraints from iron speciation and δ~(13) Corg in the Diben section,Zhejiang

Cherts of the Piyuancun Formation and black mudstones of the Hetang Formation in Diben Town, Kaihua County, Zhejiang were deposited in a deep water basin of the Lower Yangtze area during the Ediacaran–Cambrian transition(E–C transition), offering an opportunity to reconstruct the ancient redox condition of the deep water basin. Total 53 samples were collected and analyzed for iron speciation, including pyrite iron(FePy), carbonate associated iron(FeCarb), iron oxide and hydroxide(FeOx),magnetite iron(FeMag) and total iron(FeT) as well as d13 Corgto gain a deeper understanding of specific redox condition during the period. The results show that(1) most samples have pyrite concentration \1 %, with the FePy/FeHR ratio ranging from \0.01 to 0.81(mostly \0.5), and the FeHR/FeT ratio between 0.39 and 0.93(mostly [0.5).(2) The E–C boundary in the Diben section occurred at the maximum negative excursion of organic carbon isotope within the Piyuancun Formation, which can be correlated with other sections by using d13 Corg. We thus concluded that the relatively high content of highly reactive iron and low content of pyrite iron in the Diben section indicate a minor occurrence of H2 S and a predominance of anoxic and ferruginous environment, which is similar to other reported sections such as the Longbizui and Yanwutan sections, western Hunan. In addition, oxygen concentration in sea water showed an increasing trend in the interval corresponding to the bottom and upper layer of the Hetang Formation as indicated by the FeHR/FeT ratio, which decreased from 0.7 to 0.38, however, it was not great enough to oxidize the whole deep water. Therefore, during the E–C transition deep water basin in South China was most likely an anoxic and ferruginous enrironment, which prevented metazoon from the evolution in the deep water basin. Our work offers an important reference to better understanding of the spatiotemporal occurrence and dynamic processes of the ‘‘Cambrian Explosion'.