Interference in Complex CDMA-OFDM/OQAM for Better Performance at Low SNR

This article is about orthogonal frequency-division multiplexing with quadrature amplitude modulation combined with code division multiplexing access for complex data transmission. It aims to present a method which uses two interfering subsets in order to improve the performance of the transmission scheme. The idea is to spread in a coherent manner some data amongst two different codes belonging to the two different subsets involved in complex orthogonal frequency-division multiplexing with quadrature amplitude modulation and code division multiplexing access. This will improve the useful signal level at the receiving side and therefore improve the decoding process especially at low signal to noise ratio. However, this procedure implies some interference with other codes therefore creating a certain noise which is noticeable at high signal to noise ratio.

西藏列廷冈铁多金属矿床磁铁矿元素地球化学特征及地质意义

西藏列廷冈矿床是林周盆地Fe-Mo-Cu-Pb-Zn矿集区内近年来新发现不久、规模较大的矽卡岩型铁多金属矿床。矿区磁铁矿发育,主要包括块状、浸染状和脉状3种类型。基于详细的野外地质调查和室内矿相学研究,将矿床成矿期划分为矽卡岩期和热液期2期,进而划分为5个成矿阶段:早期矽卡岩阶段、退化蚀变阶段、早期热液阶段、石英-硫化物阶段和碳酸盐阶段,其中,块状磁铁矿主要形成于退化蚀变阶段,浸染状和脉状磁铁矿主要形成于早期热液阶段。以磁铁矿为主要研究对象,采用电子探针(EPMA)和单矿物微量稀土元素ICP-MS分析实验,重点对磁铁矿元素地球化学特征、成因矿物学进行系统研究。研究结果表明,3种不同类型磁铁矿内均含Ti、Si、Ca等次要元素以及Na、K、Cr、Ni、Co、Pb、Ba、Sn、Sr、Sb、Cu等多种可检测到的微量元素,且矿物内主要发生了Al、Mg、Mn等元素的类质同像置换,综合TiO_2-Al_2O_3-MgO、TiO_2-Al_2O_3-(MgO+Mn O)和(Ca+Al+Mn)-(Ti+V)、Ni/(Cr+Mn)-(Ti+V)等多种磁铁矿成因判别图解投图结果及矿体野外宏观地质特征,表明矿区磁铁矿均为热液成因。块状磁铁矿具明显的Eu正异常,浸染状和脉状磁铁矿具Eu负异常,均无明显Ce异常特征,表明富Eu成矿流体在矽卡岩期的高温氧化环境下形成了矽卡岩型块状磁铁矿体,在热液期则逐渐转变为低温还原环境,形成浸染状和脉状磁铁矿及多种金属硫化物,且铁的物质来源主要与矿区花岗闪长岩和花岗斑岩紧密相关。

正在此情深处:从《雅歌》8:1-7的语境析Qin’a的意义

在《雅歌》的华彩片段(8:6),qin’a与’ah?ba("爱情")形成同义对仗,然而其语意却颇有争议。它常被解读为针对或实或虚第三者的"嫉妒",或者生理性的"激情"。虽然两者在其他关于爱情的文本中都可以是爱情的同义词,但是它们都不能契合这对词出现的周边语境。因为语境对确定一个词的意义有关键作用,对qin’a这个词的解读也需要结合其语境(包括上下文和读者的诗歌体验)。本文将梳理《雅歌》8:6周边的三个诗歌单元(《雅歌》8:1-4,5,6-7),并结合《雅歌》中"在场与缺席"的主题,以推导本地语境所期待的qin’a之语意。这一系列文字分析也揭示出,女子的告白以她背负爱情的甜蜜痛苦为原动力。因此,笔者提议取qin’a的辞典第三种解释"承受痛苦",认为在爱情的语境里它可以理解为不知所起、一往而深的"深情"。它教人身不由己地背负那无法放下也不可替代的情感,在分隔和吸引之间忍耐,唯有向他者请求亲近的关系才能达成和平。以此"深情"与"爱情"相唱和,显示《雅歌》所见证的爱让人体会到,爱是要人背负而不是主宰的,而人的根基也不是自我的独立而是对他者的回应。

Lu-Hf Isotopic Data of the Mbé-Sassa-Mbersi Tonalite (Central Cameroon Domain): Indicator of ca. 1.0 Ga Juvenile Tonian Magmatism in the Region

The Pan-African/Brasiliano orogenic belts are a part of numerous Neoproterozoic orogenic belts that belong to the long-lived orgenic cycle that distancing phase started at the Tonian around 1.0 Ga. The Tonian magmatism fairly documented in the Neoproterozoic belts of Borborema Province (NE-Brazil), seemed so far inexistent in the Central African Orogenic Belt (CAOB) although these two belts were geologically correlated. Through the Lu-Hf geochronological analysis on zircon of tonalite, the present work, coupled with the previous data, suggests the existence of a Tonian age magmatism in the Central Cameroon Domain of the CAOB although the latter is much reworked. The Nguesseck tonalite outcrops in the northern part of the Mbé-Sassa-Mbersi region, in the northern edge of Central Cameroon Domain of the CAOB and in the Tcholliré-Banyo shear zone (TBSZ). The Lu-Hf data obtain on the zircon grains of this tonalite reveal juvenile HfTDM age of ca. 1.0 Ga. This age, combined to the previous geochemical data suggests that the protholites of this tonalite would have extracted from the source during the distancing phase (rifting and oceanization) of the Pan-african/Brasiliano orogeny at the early Neoproterozoic.