唐山断裂带的板内重复地震识别及其滑动速率估算

华北地区以强烈的新构造运动、众多的板内地震、多发的破坏性地震著称.1976年7月28日发生在北京东约160km处的唐山7.8级大地震是历史上人员伤亡最为惨重的灾害之一.唐山断裂带是唐山大地震的主控断裂,由一系列互相平行的NNE向的走滑断裂组成,由于在构造表现和运动方式等方面存在明显的差异,基本上可划分为南、北两段.     

甘蒙地区北山盆地群中口子盆地侏罗系烃源岩特征及评价

北山盆地群侏罗系是我国西北地区潜在的油气勘探新领域,为深化其石油地质认识,进一步明确资源潜力,优选北山盆地群中勘探程度相对较高的中口子盆地侏罗系为研究对象,以有机质丰度、类型及成熟度等有机地球化学分析数据为基础,分析了侏罗系烃源岩基础特征,并基于生物标志化合物资料,探讨了该区侏罗系烃源岩的有机质来源及沉积环境。结果表明,中口子盆地侏罗系烃源岩有机质丰度较高,生烃潜力较好,主要为中等-好烃源岩,干酪根类型以Ⅱ2型为主,生烃母质主要是陆源高等植物,主要形成于氧气量适中的弱氧化-弱还原古环境,靠近或位于凹陷中心的烃源岩形成环境还原性稍强,较有利于有机质保存。区内黑帐房凹陷烃源岩已经成熟,而南泉凹陷烃源岩主要为低熟。因此建议黑帐房凹陷中心或者临近中心区域,寻找保存条件好的油藏是取得下步油气勘探突破的重点。这些认识可供西北地区侏罗系沉积古环境和资源潜力研究时对比参考。     

沙地玉米水分利用效率日变化特征

以科尔沁沙地玉米农田生态系统为研究对象,利用涡度相关技术和便携式光合作用测定系统（LI-COR6400）同步观测玉米（郑单958）主要生育期（苗期、拔节期、抽穗期、灌浆期和成熟期）群体和叶片尺度瞬时CO₂交换及水汽交换速率,并分析其水分利用效率的日变化特征。结果表明：各生育期玉米群体尺度瞬时CO₂交换速率分别为-2.205、-26.113、-26.118、-8.201、-3.672 μmolCO₂·m^-2·s^-1,叶片尺度光合速率分别为27.57、59.55、24.38、22.03、20.09 μmolCO₂·m^-2·s^-1。各生育期群体水分利用效率（WUE_C）的日动态呈现“L”型,峰值出现在日出后（约06：00）,分别为0.025、0.039、0.088、0.058、0.191 gCO₂·g^-1H₂O,叶片尺度瞬时水分利用效率（WUE_L）的日动态呈“~”型,峰值出现在06：00—10：00,分别为0.029、0.041、0.017、0.019、0.024 gCO₂·g^-1H₂O。玉米各生育期群体及叶片尺度瞬时CO₂交换速率和水分利用效率均存在明显差异。     

Spatial-temporal variability of throughfall in a subtropical deciduous forest from the hilly regions of eastern China

Throughfall variability plays a crucial role in regulating hydrological and biogeochemical processes in forest ecosystems. However, throughfall variability and its potential influencing factors remain unclear in the subtropical deciduous forest because of its complex canopy and meteorological conditions. Here, the spatial variability and temporal stability of throughfall were investigated from October 2016 to December 2017 within a deciduous forest in the subtropical hilly regions of eastern China, and the effects of meteorological variables and distance from nearest tree trunk on throughfall variability were systematically evaluated. Throughfall variability during the leafed period was slightly higher than that during the leafless period inferred from the coefficient of variation of throughfall amounts(CVTF), with 13.2%-40.9% and 18.7%-31.9%, respectively. The multiple regression model analysis suggested that the controlling factors of throughfall variability were different in studied periods: Maximum 10-min rainfall intensity, wind speed and air temperature were the dominant influencing factors on throughfall variability during the leafed period, with the relative contribution ratio(RCR) of 25.9%, 18.7% and 8.9%, respectively. By contrast, throughfall variability was affected mainly by the mean rainfall intensity(RCR=40.8%) during the leafless period. The temporal stability plots and geostatistical analysis indicated that spatial patterns of throughfall were stable and similar among rainfall events. Our findings highlight the important role of various meteorological factors in throughfall variability and are expected to contribute to the accurate assessment of throughfall, soil water and runoff within the subtropical forests.     

The design and implementation of a ROACH2+GPU based correlator on the Tianlai dish array

A digital correlator is a crucial element in a modern radio telescope. In this paper, we describe a scalable design for the correlator system of the Tianlai pathfinder array, which is an experiment dedicated to testing key technologies for conducting a 21 cm intensity mapping survey. The correlator implements the FX design, which firstly performs a fast Fourier transform(FFT) including polyphase filter bank(PFB) computation using a Collaboration for Astronomy Signal Processing and Electronics Research(CASPER) Reconfigurable Open Architecture Computing Hardware-2(ROACH2) board, then computes cross-correlations by employing Graphics Processing Units(GPUs). The design has been tested both in laboratory and in actual observation.     

Impulsive control of stochastic system under the sense of stochastic asymptotical stability

This paper studies the stochastic asymptotical stability of stochastic impulsive differential equations, and establishes a comparison theory to ensure the trivial solution's stochastic asymptotical stability. From the comparison theory, it can find out whether the stochastic impulsive differential system is stable just by studying the stability of a deterministic comparison system. As a general application of this theory, it controls the chaos of stochastic Lü system using impulsive control method, and numerical simulations are employed to verify the feasibility of this method.     

Spot and Facula Activity Variations of the Eccentric Detached Eclipsing Binary KIC 8098300 Based on the Time-series Orbital Solutions

The LAMOST spectra and Kepler light curves are combined to investigate the detached eclipsing binary KIC 8098300,which shows the O'Connell effect caused by spot...     

Grain-size distribution characteristics of red sandy sediments in Dongjiang River valley, southern Nanling Mountains, during the MIS2 stage

Layer LJ3 of Linjiang stratigraphic section in Dongjiang River valley in the south of the Nanling Mountains is a set of red sandy sediments.Measured by thermoluminescence(TL) dating,it was found to be formed in MIS2-9,500 ± 800 yr to 19,600 ± 1,800 yr B.P.After analy-sis of the grain sizes of the 16 samples(LJ3-100 to LJ3-85) in this layer,it was discovered that(1) The contents of each grain group in dif-ferent samples are similar.(2) The values of Md,Mz,,Sk,and Kg vary from LJ3-100 to LJ3-85 in a narrow range.(3) The segments of each sample in the accumulative curves extend parallel with similar slopes.All the three aspects reveal the Aeolian characteristics of Layer LJ3.Therefore,it is thought that Layer LJ3 consists of red sandy sediments formed in MIS2 in the south of Nanling Mountain,which reflects the arid climate at that time.     

Research on the Relationship between Active Faults and Earthquakes in the Junction Area of the China North-South Seismic Belt and Central Orogenic Belt Based on GIS

Research on the relationship between faults and seismicity in the junction area of China's north-south seismic belt and central orogenic belt based on the Geography Information System (GIS) has been done.For each of the 16 faults in this area,we build a 25km buffer zone and use overlay analysis to investigate the seismicity and its characteristics on each fault.The results unveil the main seismic faults as follows:the western segment of the northern-edge of the west Qinling fault,the southwestern segment of the Lixian-Luojiabao fault,the southeastern segment of the Lintan-Dangchang fault,the southwestern segment of the Wenxian fault,the Huya fault,and the Xueshan fault.The most active faults are the Huya and Xueshan faults,then the Tazang fault,the Lixian-Luojiabao fault and the northern piedmont of the Guanggaishan-Dieshan fault.The research zone can be divided into four areas according to focal depth,which gets deeper from north to south.The profile of focal depth indicates the geometry and mechanical property of faults,and further reveals the movement model of eastward extrusion of the Tibetan plateau and southeastward escape of masses,thus providing basis for the protection against earthquakes and hazard mitigation in this area.     

Estimation of gross primary production in wheat from in situ measurements

Gross primary production (GPP) is a parameter of significant importance for carbon cycle and climate change research. Remote sensing combined with other climate and meteorological data offers a convenient tool for large scale GPP estimation. This paper presents a study of GPP estimation using three methods with in situ measurements of canopy reflectance, LAI, and the photosynthetically active radiation (PAR). First, because LAI is considered as an indicator of the factor of absorbed PAR (f_APAR), it provides reasonable estimates of GPP for all types of wheat with coefficient of determination R² of 0.7353. The second method uses four kinds of vegetation indices (VIs) to estimate GPP because these indices are suggested to be reliable candidates in the estimation of light use efficiency (LUE). Good determination coefficients were acquired in estimating GPP with R² ranging from the lowest of 0.7604 for NDVI to the highest of 0.8505 for EVI. A new method was proposed for the estimation of GPP following the Monteith logic, which considering GPP as a product of VI × VI × PAR. Results indicated that this method can provide the best estimates of GPP as determination coefficient R² increased largely compared to the other two methods. EVI × EVI × PAR was demonstrated to be the most suitable for the estimation of GPP with the highest R² of 0.9207, which was about 10% larger as compared to GPP estimated from the single EVI. These results will be helpful for the development of new models of GPP estimation with all remote sensing inputs.