The Central Africa Fold Belt(CAFB)is a collision belt endowed with gold deposits in Eastern Cameroon area mined for about 50 years.However,favorable areas for gold exploration are poorly known.This paper presents(1)th...The Central Africa Fold Belt(CAFB)is a collision belt endowed with gold deposits in Eastern Cameroon area mined for about 50 years.However,favorable areas for gold exploration are poorly known.This paper presents(1)the kinematics of the brittle deformation in the Kékem area in the SW portion of the Central Cameroon Shear Zone and(2)constraints gold mineralization events with respect to the collisional evolution of the CAFB.The authors interpret that the conjugate ENE to E and NNW to NW trending lineament corresponds to the synthetic(R)and the antithetic(R’)shears,which accompanied the dextral slip along the NE to ENE striking shear.The latter coincides with the last 570-552 Ma D3 dextral simple shear-dominated transpression,which is parallel to the BétaréOya shear zone hosting gold deposits.Gold mineralizations,which mainly occurred during the last dextral shearing,are disseminated within quartz veins associated to Riedel’s previous structures reactivated due to late collisional activities of the CAFB as brittle deformation.Gold mineralizations occurred mainly during the 570-552 Ma D3 event.The reactivation,which might be due to dextral simple shear during mylonitzation,plausibly remobilized the early gold deposits hosted in syn-compressional rocks and/or possibly focused deep-sourced fluid mixed with those released by dehydration.Therefore,the Central Cameroon Shear Zone where Kékem is located,and which shows similar petrographical and structural features to those controling Batouri gold district,is a target area for gold exploration in Cameroon.展开更多
基于塑性极限分析的运动单元法(kinematical element method)提出一种边坡稳定状况快速辨识方法。研究岩土体参数组合(坡高H、黏聚力c、内摩擦角和重度γ)与安全系数F和滑动面位置间的内在联系。在此基础上,绘制边坡稳定分析图,求解不...基于塑性极限分析的运动单元法(kinematical element method)提出一种边坡稳定状况快速辨识方法。研究岩土体参数组合(坡高H、黏聚力c、内摩擦角和重度γ)与安全系数F和滑动面位置间的内在联系。在此基础上,绘制边坡稳定分析图,求解不需要任何迭代,可快速求解安全系数和滑动面位置。根据边坡稳定分析图,提出一种新的参数反演方法。结果表明,无量纲参数c/(Htan)控制着滑动面位置和F/tan。λ不变,则滑动面位置和F/tan保持不变;λ越大,边坡失稳模式由浅层破坏变为深层破坏,滑动面坡顶滑出点离坡肩越来越远。当λ>0.2时,λ与F/tan符合线性关系,可用拟合公式快速计算安全系数。根据原始边坡形态和滑动面坡顶滑出点离坡肩的距离,即可快速反算滑带岩土体的黏聚力和内摩擦角。展开更多
The functions of digital signature and public key encryption are simultaneously fulfilled by signcryption,which is a cryptographic primitive.To securely communicate very large messages,the cryptographic primitive call...The functions of digital signature and public key encryption are simultaneously fulfilled by signcryption,which is a cryptographic primitive.To securely communicate very large messages,the cryptographic primitive called signcryption efficiently implements the same and while most of the public key based systems are suitable for small messages,hybrid encryption(KEM-DEM)provides a competent and practical way.In this paper,we develop a hybrid signcryption technique.The hybrid signcryption is based on the KEM and DEM technique.The KEM algorithm utilizes the KDF technique to encapsulate the symmetric key.The DEM algorithm utilizes the Adaptive Genetic Algorithm based Elliptic curve cryptography algorithm to encrypt the original message.Here,for the security purpose,we introduce the three games and we proved the attackers fail to find the security attributes of our proposed signcryption algorithm.The proposed algorithm is analyzed with Daniel of Service(DOS),Brute Force attack and Man In Middle(MIM)attacks to ensure the secure data transaction.展开更多
文摘The Central Africa Fold Belt(CAFB)is a collision belt endowed with gold deposits in Eastern Cameroon area mined for about 50 years.However,favorable areas for gold exploration are poorly known.This paper presents(1)the kinematics of the brittle deformation in the Kékem area in the SW portion of the Central Cameroon Shear Zone and(2)constraints gold mineralization events with respect to the collisional evolution of the CAFB.The authors interpret that the conjugate ENE to E and NNW to NW trending lineament corresponds to the synthetic(R)and the antithetic(R’)shears,which accompanied the dextral slip along the NE to ENE striking shear.The latter coincides with the last 570-552 Ma D3 dextral simple shear-dominated transpression,which is parallel to the BétaréOya shear zone hosting gold deposits.Gold mineralizations,which mainly occurred during the last dextral shearing,are disseminated within quartz veins associated to Riedel’s previous structures reactivated due to late collisional activities of the CAFB as brittle deformation.Gold mineralizations occurred mainly during the 570-552 Ma D3 event.The reactivation,which might be due to dextral simple shear during mylonitzation,plausibly remobilized the early gold deposits hosted in syn-compressional rocks and/or possibly focused deep-sourced fluid mixed with those released by dehydration.Therefore,the Central Cameroon Shear Zone where Kékem is located,and which shows similar petrographical and structural features to those controling Batouri gold district,is a target area for gold exploration in Cameroon.
文摘密钥封装机制(key encapsulation mechanism,KEM)使得会话双方能够安全地共享一个随机的会话密钥,改善了使用公钥加密明文时空间受限的问题,是大规模网络中密钥分发和密钥管理问题的有效解决方案之一。提出一种标准模型下安全高效的格上的密钥封装机制,将陷门函数与带误差学习问题(learning with errors,LWE)算法相结合,并引入参与者的身份信息,保证密钥封装机制的机密性和可认证性,可抵抗现有已知量子算法攻击。采用密文压缩技术,对封装后的密文元素进行压缩,分析结果表明,能够有效提高传输效率。在标准模型下,该机制安全性归约至判定性LWE的难解性,并包含严格的安全性证明。其安全性为可证明的选择密文安全,适用于多种类型基于格的密钥交换协议方案。
文摘基于塑性极限分析的运动单元法(kinematical element method)提出一种边坡稳定状况快速辨识方法。研究岩土体参数组合(坡高H、黏聚力c、内摩擦角和重度γ)与安全系数F和滑动面位置间的内在联系。在此基础上,绘制边坡稳定分析图,求解不需要任何迭代,可快速求解安全系数和滑动面位置。根据边坡稳定分析图,提出一种新的参数反演方法。结果表明,无量纲参数c/(Htan)控制着滑动面位置和F/tan。λ不变,则滑动面位置和F/tan保持不变;λ越大,边坡失稳模式由浅层破坏变为深层破坏,滑动面坡顶滑出点离坡肩越来越远。当λ>0.2时,λ与F/tan符合线性关系,可用拟合公式快速计算安全系数。根据原始边坡形态和滑动面坡顶滑出点离坡肩的距离,即可快速反算滑带岩土体的黏聚力和内摩擦角。
文摘The functions of digital signature and public key encryption are simultaneously fulfilled by signcryption,which is a cryptographic primitive.To securely communicate very large messages,the cryptographic primitive called signcryption efficiently implements the same and while most of the public key based systems are suitable for small messages,hybrid encryption(KEM-DEM)provides a competent and practical way.In this paper,we develop a hybrid signcryption technique.The hybrid signcryption is based on the KEM and DEM technique.The KEM algorithm utilizes the KDF technique to encapsulate the symmetric key.The DEM algorithm utilizes the Adaptive Genetic Algorithm based Elliptic curve cryptography algorithm to encrypt the original message.Here,for the security purpose,we introduce the three games and we proved the attackers fail to find the security attributes of our proposed signcryption algorithm.The proposed algorithm is analyzed with Daniel of Service(DOS),Brute Force attack and Man In Middle(MIM)attacks to ensure the secure data transaction.
