On the intrinsic shape of the gamma-ray spectrum for Fermi blazars

The curvature of the γ-ray spectrum in blazars may reflect the intrinsic distribution of emitting electrons, which will further give some information on the possible acceleration and cooling processes in the emitting region. The γ-ray spectra of Fermi blazars are normally fitted either by a single power-law(PL) or a log-normal(call Logarithmic Parabola, LP) form. The possible reason for this difference is not clear. We statistically explore this issue based on the different observational properties of 1419 Fermi blazars in the 3 LAC Clean Sample. We find that the γ-ray flux(100 Me V–100 Ge V) and variability index follow bimodal distributions for PL and LP blazars, where the γ-ray flux and variability index show a positive correlation. However, the distributions of γ-ray luminosity and redshift follow a unimodal distribution. Our results suggest that the bimodal distribution of γ-ray fluxes for LP and PL blazars may not be intrinsic and all blazars may have an intrinsically curved γ-ray spectrum, and the PL spectrum is just caused by the fitting effect due to less photons.     

一种基于OpenMP的高效GPS卫星钟差实时估计方法

提出基于单观测值的Kalman滤波快速计算方法,并引入共享存储并行编程（OpenMP）技术实现协方差快速更新,从而实现非差GPS卫星钟差的快速实时计算。均匀选取55个IGS参考站,计算2017-03-20~03-30采样率为60 s的卫星钟差。与IGS事后30 s钟差相比,两者具有很好的一致性,RMS互差优于0.5 ns。选取未参与钟差解算的10个IGS参考站进行精密单点定位,结果表明,实时静态PPP水平方向精度优于2 cm,高程方向精度为2~4 cm;实时动态PPP水平方向精度为2～4 cm,高程方向精度为4～6 cm,能够满足实时PPP的精度要求。该方法在主频1.2 GHz服务器上8线程并行模式下单历元耗时4 s,相比串行模式效率提升1/3。     

Wave-induced Maintenance of Suspended Sediment Concentration during Slack in a Tidal Channel on a Sheltered Macro-tidal Flat,Gangwha Island,Korea

A field campaign was conducted to better understand the influence of wave action, in terms of turbulence and bed shear stress, on sediment resuspension and transport processes on a protected tidal flat. An H-frame was deployed in a tidal channel south of Gangwha Island for 6 tidal cycles during November 2006 with instrumentation including an Acoustic Doppler Velocimeter, an Acoustic Backscatter System, and an Optical Backscatter Sensor. During calm conditions, the current-induced shear was dominant and responsible for suspending sediments during the accelerating phases of flood and ebb. During the high-tide slack, both bed shear stress and suspended sediment concentration were reduced. The sediment flux was directed landward due to the scour-lag effect over a tidal cycle. On the other hand, when waves were stronger, the wave-induced turbulence appeared to keep sediments in suspension even during the high-tide slack, while the current-induced shear remained dominant during the accelerating phases of flood and ebb. The sediment flux under strong waves was directed offshore due to the sustained high suspended sediment concentration during the high-tide slack. Although strong waves can induce offshore sediment flux, infrequent events with strong waves are unlikely to alter the long-term accretion of the protected southern Gangwha tidal flats.     

Sr掺杂Eu1-xSrxMnO3体系的磁相变以及输运特性研究

对Eu_1-xSr_xMnO₃ (ESMO, x=0—1)体系的结构和磁性进行了系统的研究,结果表明Sr的掺入使EuMnO₃反铁磁母体的磁结构发生巨大的变化.通过磁化和电输运测量,深入探讨了高掺杂浓度Eu_0.4Sr_0.6MnO₃和Eu_0.3Sr_0.7MnO_{3相似文献}   

磺胺二甲嘧啶在大菱鲆体内的药代动力学研究

在水温(15±1)℃条件下,给大菱鲆以100 mg/kg的剂量灌服磺胺二甲嘧啶后,用HPLC法测得96h内大菱鲆肌肉、血浆、肝脏中磺胺二甲嘧啶的浓度。用DAS 2.0软件分析后表明,磺胺二甲嘧啶在大菱鲆肌肉、血浆和肝脏中药代动力学模型均为一房室开放模型,肌肉、血浆和肝脏中的消除相半衰期T1/2和吸收相半衰期T1/2ka分别为27.413h、8.8h、5.715h和1.526h、0.919h、1.358h;出现达峰时间Tmax为8h、4h、6h;最高药物浓度Cmax为31.486μg/mL、40.256μg/mL、26.475μg/mL;总体消除率CL/F为0.069L/h.kg、0.142L/h.kg、0.312L/h.kg;药物浓度-时间曲线下面积AUC为1178.428 mg/L.h、702.739 mg/L.h、320.015 mg/L.h;建议在水温15℃下使用磺胺二甲嘧啶进行大菱鲆疾病的预防和治疗时,至少停药36d后方可上市销售。     

毛乌素沙区1961-2016年降水特征

基于毛乌素沙区10个气象站1961-2016年观测资料,应用Mann-Kendall方法和t检验法对各气象站年降水量进行了突变检验,借助小波分析讨论了各气象站年降水量的周期特征,根据降水量等值线划分结果对整个研究区分区分析了年、季、月和日尺度上的降水变化特征,并在两个时段上分析了季节性降水的差异。结果表明：毛乌素沙区年降水量空间特征差异明显,东部亚区呈上升趋势,中西部亚区呈下降趋势,但变化趋势不显著且无突变发生;降水年内分配不均,干湿季分明,降水集中在5-9月,夏秋季降水占全年降水比重大,季、月和日尺度降水量存在梯度递减变化;年降水量的年际变化过程存在多重时间尺度的自相似结构;近26年的冬春季降水增加显著,但降水波动幅度小于前30年。     

福建省城市扩张与经济增长的互动关系研究

基于2000~2015年福建省9个设区市的城市建成区面积与非农GDP的历史数据,根据生态位理论将9个设区市分为4个等级,结合库兹涅兹曲线分析、协整检验及Granger因果关系分析、脱钩分析3种方法对不同等级城市之间的城市扩张和经济发展的互动关系进行了研究。研究表明:福建省城市生态位呈现东高西低,南高北低的空间格局;9个设区市均符合广义的库兹涅兹曲线关系,但只有高生态位城市全部符合倒“U”型曲线关系;福建省多数城市用地扩张与经济增长之间的Granger因果关系受区位、政策和决策等因素影响并不明显;福建省9个设区市的脱钩关系主要呈现为增长负脱钩、弱脱钩、强脱钩和增长连接4类,绝大多数城市多数时期以弱脱钩状态为主。     

巨野煤田彭庄煤矿首采区减少煤损方法简析

山东鲁能菏泽煤电开发有限公司彭庄煤矿位于巨野煤田北部,是巨野煤田7个生产和在建煤矿（包括梁宝寺、彭庄、郭屯、赵楼、龙崮、万福、郓城等煤矿）的第一对投产的矿井。2006年8月开始试生产,2007年3月正式投产。彭庄煤矿2007年底核实保有资源量为12698．9万t,     

沙滩休闲旅游价值影响因素分析——以青岛海水浴场为例

沙滩休闲游乐价值受到沙滩的物理、化学、生物学特征及人口统计因素等各种社会、经济因素的影响,特别是游客的个体因素对沙滩休闲游乐价值具有重要的影响。通过对影响游客沙滩选择的因素进行评估,结合沙滩的游客支付意愿和环境保护意愿调查,系统地对不同自然及人口统计因素对沙滩游憩成本、沙滩使用支付意愿及环境保护意愿的影响及关联程度进行了统计分析,得出环境质量、家庭收入、沙滩游览次数等因素对沙滩休闲旅游价值具有显著影响。     

Black carbon and polycyclic aromatic hydrocarbons (PAHs) in surface sediments of China’s marginal seas

This study investigates the distribution of black carbon (BC) and its correlation with total polycyclic aromatic hydrocarbons (ΣPAH) in the surface sediments of China’s marginal seas. BC content ranges from <0.10 to 2.45 mg/g dw (grams dry weight) in the sediments studied, and varied among the different coastal regions. The Bohai Bay sediments had the highest BC contents (average 2.18 mg/g dw), which comprises a significant fraction (27%–41%) of the total organic carbon (TOC) preserved in the sediments. In ...