Microscopic black hole detection in UHECR: the double bang signature     

V. Cardoso  M.C. Espírito Santo  M. Paulos  M. Pimenta  B. Tom 《Astroparticle Physics》2005,22(5-6):399-407

According to recent conjectures on the existence of large extra dimensions in our universe, black holes could be produced during the interaction of Ultra High Energy Cosmic Rays with the atmosphere. However, and so far, the proposed signatures are based on statistical effects, not allowing identification on an event by event basis, and may lead to large uncertainties. In this note, events with a double bang topology, where the production and instantaneous decay of a microscopic black hole (first bang) is followed, at a measurable distance, by the decay of an energetic tau lepton (second bang) are proposed as an almost background free signature. The characteristics of these events and the capability of large cosmic ray experiments to detect them are discussed.  相似文献   

“双十一”期间中国快递流通的时空结构与效率——基于时间地理学视角   总被引：2，自引：0，他引：2  

李鲁奇  孔翔 《地理研究》2019,38(8):1891-1904

“双十一”作为电商促销活动,其引致的短期高强度快递服务需求对快递业造成极大压力。借鉴时间地理学方法,基于宅急送公司2017年数据,对“双十一”期间中国快递流通的时空结构与效率进行分析。研究表明：快递流通整体上速度较快并由沿海向内陆扩散,在空间结构上各地区快递主要来自其内部和华东地区,在时间结构上绝大多数快递在2~5 d左右即可完成全部配送流程,且耗时主要集中于运输环节。此外,取件、离开、派送活动仍保持原有周期性,但在1 d内的时间分配趋于均衡;路径束主要呈水滴状、分段式形态,快递压力集中于少数枢纽城市,快递处理能力则呈现分层特征。  相似文献   

A computational model for coupled multiphysics processes of CO2 sequestration in fractured porous media     

《Advances in water resources》2013

In this paper, a computational model for the simulation of coupled hydromechanical and electrokinetic flow in fractured porous media is introduced. Particular emphasis is placed on modeling CO₂ flow in a deformed, fractured geological formation and the associated electrokinetic flow. The governing field equations are derived based on the averaging theory and the double porosity model. They are solved numerically with a mixed discretization scheme, formulated on the basis of the standard Galerkin finite element method, the extended finite element method, the level-set method and the Petrov–Galerkin method. The standard Galerkin method is utilized to discretize the equilibrium and the diffusive dominant field equations, and the extended finite element method, together with the level-set method and the Petrov–Galerkin method, are utilized to discretize the advective dominant field equations. The level-set method is employed to trace the CO₂ plume front, and the extended finite element method is employed to model the high gradient in the saturation field front. The proposed mixed discretization scheme leads to a convergent system, giving a stable and effectively mesh-independent model. The accuracy and computational efficiency of the proposed model is evaluated by verification and numerical examples. Effects of the fracture spacing on the CO₂ flow and the streaming potential are discussed.  相似文献   

NI4472在海洋噪声和传播损失测量中的应用   总被引：1，自引：0，他引：1  

崔华义  周长兴 《海洋技术学报》2003,22(3):74-75

利用NI公司的高性能数据采集板NI4472来进一步改善海洋噪声和传播损失的测量情况。  相似文献   

大气粒子散射相函数的参数化方案比较及其改进     

刘琨  张峰  吴琨  周秀骥  张华  刘仁强 《气象学报》2016,74(5):784-795

大气粒子散射相函数的参数化是大气辐射传输参数化的重要组成部分。文中全面比较了大气粒子的HenyeyGreenstein(HG)方案和双Henyey-Greenstein(DHG)方案,并在四流球谐函数展开累加法中,应用这两种相函数参数化方案计算气溶胶、云、霾粒子的反射率、透射率或吸收率。该研究结果表明:HG方案无法表现相函数的后向峰值,因而其计算的大气粒子反射率和透射率精度较差;DHG方案能较好地表征相函数的整体特征,但是该方案计算的相函数易出现后向异常峰值或为负值,并导致计算得到的气溶胶、云、霾粒子的反射率和透射率精度甚至会低于HG方案。对DHG方案进行进一步研究,提出了改进的DHG方案(MDHG)。MDHG方案计算结果稳定,并能很好表征相函数的前向和后向峰值的特征,其计算的大气粒子的反射率和透射率精度也较高。因此,MDHG方案是一种理想的相函数参数化方案。  相似文献   

近台资料对近震相对定位算法的影响   总被引：10，自引：2，他引：10       下载免费PDF全文

张天中  武巴特尔  黄媛  蒋长胜 《地球物理学报》2007,50(4):1123-1130

从地震定位的基本原理出发，分析认为近台资料可用于双差定位算法，但不能用于其他相对定位方法.在此基础上，通过分析和模拟计算表明，应用近台资料时，双差法有可能给出一定精度的地震绝对位置.但仅采用近台资料时，相对位置的误差会比使用远台资料时有所增加.近台和远台资料的联合使用，有利于得到较为精确的定位结果.当震源深度远小于震中距时，如果没有深度震相的参与，只能得到误差较小的震中相对分布，深度的相对位置仍有较大的误差.对2003年新疆伽师地震余震序列中部分余震的重新定位试验，验证了近台资料对双差定位算法的上述影响.  相似文献   

新疆北天山地区Ms≥2.0地震震源参数的重新测定   总被引：4，自引：1，他引：4  

王海涛  李志海  赵翠萍  曲延军 《中国地震》2007,23(1):47-55

基于新疆32个测震台站记录到的28701条P波和S波震相到时数据,利用双差地震定位法重新测定新疆北天山地区(42.5°~45°N,82°~89°E)1988年4月至2003年6月间发生的1348次MS≥2.0地震的震源位置。为尽量得到全部地震的重新定位结果,本文结合双差地震定位法对资料的要求和所用资料情况,添加了437次1.5≤MS<2.0的地震震相到时数据参与定位计算。重新定位后得到了1253次MS≥2.0地震的重新定位结果,占全部MS≥2.0地震的93%,其中,MS≥3.0的地震全部得到了重新定位结果,并对没有得到重新定位结果的95次2.0≤MS<3.0地震的原因进行了分析。得到重新定位结果的1253次地震的均方根残差的平均值由重新定位前的0.83s降到0.14s,震源位置的测定误差(2倍标准偏差)在E-W方向平均为0.993km,在N-S方向上平均为1.10km,垂直方向平均为1.33km。分析重新定位结果得出,重新定位地震的震源深度较定位前有明显收敛,集中分布在5~35km,94.3%的地震震源深度分布在5~35km,68.2%的地震震源深度分布在10~25km,地震的平均震源深度为19km。  相似文献   

Sedimentation–consolidation of a double porosity material     

Henry Wong  Chin J. Leo  J.M. Pereira  Ph. Dubujet 《Computers and Geotechnics》2007,34(6):532-538

This paper studies the sedimentation–consolidation of a double porosity material, such as lumpy clay. Large displacements and finite strains are accounted for in a multidimensional setting. Fundamental equations are derived using a phenomenological approach and non-equilibrium thermodynamics, as set out by Coussy [Coussy, Poromechanics, Wiley, Chichester, 2004]. These equations particularise to three non-linear partial differential equations in one dimensional context. Numerical implementation in a finite element code is currently being undertaken.  相似文献   

Relocation of the Ms≥2.0 Earthquakes in the Northern Tianshan Region, Xinjiang, Using the Double-Difference Earthquake Relocation Algorithm     

Wang Haitao 《中国地震研究》2007,21(4):388-396

We applied the double-difference earthquake relocation algorithm to 1348 earthquakes with M_S≥2.0 that occurred in the northern Tianshan region, Xinjiang, from April 1988 to June 2003, using a total of 28701 P- and S-wave arrival times recorded by 32 seismic stations in Xinjiang. Aiming to obtain most of these M_S≥2.0 earthquakes relocations, and considering the requirements of the DD method and the condition of data, we added the travel time data of another 437 earthquakes with 1.5≤M_S<2.0. Finally, we obtained the relocation results for 1253 earthquakes with M_S≥2.0, which account for 93% of all the 1348 earthquakes with M_S≥2.0 and includes all the M_S≥3.0 earthquakes. The reason for not relocating the 95 earthquakes with 2.0≤M_S<3.0 is analyzed in the paper. After relocation, the RMS residual decreased from 0.83s to 0.14s, the average error is 0.993 km in E-W direction, 1.10 km in N-S direction, and 1.33 km in vertical direction. The hypocenter depths are more convergent than before and distributed from 5 km to 35 km, with 94% being from 5km to 35 km, 68.2% from 10 km to 25 km. The average hypocenter depth is 19 km.  相似文献   

河北兴隆复式叠瓦扇构造   总被引：4，自引：0，他引：4       下载免费PDF全文

姜波  刘洪章 《地质科学》1997,32(2):165-172

河北省北部兴隍-平泉复向斜的西端发育了一种特殊类型的推覆构造,该推覆构造具有三重结构的特点,即由上叠瓦扇、下叠瓦扇和下伏系统组成。上叠瓦扇可以分为被分支断裂分割的太古字、长城系、蓟县系、青白口系和寒武-奥陶系5个逆冲岩席;各分支断裂上陡下缓,向下逐渐归并于F₁主逆冲断裂上。F₁断层下的石炭-二叠系也发育了一组叠瓦状逆冲断层,形成了与上叠瓦扇具有不同变形特征的下叠瓦扇。由于这一构造特殊的两套叠瓦扇结构,故笔者称其为复式叠瓦扇构造,这是一种新的推覆构造类型。  相似文献