Petro-Structural Study of the Paleoproterozoic Formations of the Faboula Gold Deposit (Bougouni-Kékoro Basin, Leo-Man Shield)

Recent petro-structural investigations on the Faboula gold deposit located in the Bougouni-Kékoro basin, in southern Mali, north-west of the Leo-Man Shield, have provided new data on the nature and spatial organization of the lithostratigraphic units as well as their deformation style. The deposit is covered by a thick lateritic layer and is hosted by a metavolcano-sedimentary sequence of Paleoproterozoic age intersected by intrusive bodies and filled fractures of various shapes and types. The lithostratigraphic units consist of metagreywackes, metasiltstones, meta-argillites, slates and schists. Metagreywackes and metasiltstones are generally feldspathic, both may contain biotite and locally amphibole, just as slates may contain andalusite which is locally stretched. Plutonic units most often occur as stocks or as dikes on the drill core, up to 1 m. The metavolcano-sedimentary rocks are schistose and deformed under greenschist facies conditions, and locally they reach the epidote-amphibolite facies. The structural study revealed that the deposit is affected by several stages of deformation evolving from a ductile type to a brittle type via a ductile-brittle type. The dominant ductile and brittle-ductile deformations show a combination of isoclinal folding and strike-slip faults. Both the isoclinal folding and the strike-slip faults whose sigmoidal en-echelon tension gashes indicate a dextral movement in the NNE-SSW direction are the result of the same ENE-WSW regional shortening. Consequently, they highlight a transpressive deformation. This deformation noted here D2Fb, could be equivalent to the regional D2 or D3 deformations identified at the scale of the Leo-Man Shield if we refer to the style of deformation. There is an abundance of quartz veins networks. Their relation within the structural features indicates that the mineralization is structurally controlled during a hydrothermal event linked certainly to the circulations of fluids during the transpressive event D2Fb.

Petrographic and Geochemical Characteristics of the Granitoids in the South of Godé (North of the Square Degree of Léo-Burkina Faso, West Africa)

South of Godé, in the central-western region of Burkina Faso, granitoids of Paleoproterozoic age are similar to those of the Man/Leo shield. This study focused on the petrographic and geochemical characteristics of these granitoids, with the following results: 1) The tonalite that outcrops in the south-west of the study area belongs to the TTG group or first generation granitoids. They are most often ribboned at outcrop and have a geochemical signature close to that of Archean TTGs. Tonalite has a metaluminous character and the REE spectrum indicates that it may be derived from partial melting of basic magmatic rocks. 2) Biotite granites have no outcrop structure. They are weakly metaluminous to peraluminous and potassic to highly potassic. Their rare earth spectra indicate that they may be derived from the partial melting of TTG granitoids. 3) Geotectonic diagrams show that the granitoids studied to the south of Godé were emplaced in an active tectonic context similar to that of present-day subduction zones.

Petrographic and Geochemical Characteristics of the Pouni Palaeoproterozoic Formations North of the Léo Square Degree (Burkina Faso, West Africa)

The Pouni area is made up of basalts belonging to the Boromo belt, lamprophyres and granitoids. These geological formations are similar to geological formations of the same type in other regions of the Palaeoproterozoic domain of the Man/Leo shield. This study, which focused on the petrographic and geochemical characteristics of these geological formations, led to the following main conclusions: The lamprophyres are basic plutonic rocks that cut through other geological formations. The basalt belongs to the northern part of the Borormo belt and is thought to be a relic of overthickened oceanic plateaus. There are two groups of granitoid rocks. The granodiorite has a geochemical signature close to that of Archean TTGs and is metaluminous in character. It has a low potassium content. The minor element and rare earth element spectra indicate that it could be derived from partial melting of basic magmatic rocks. Biotite granites are peraluminous and highly potassic. Minor element contents and rare earth spectra indicate that they could be derived from partial melting of felsic materials. Geotectonic diagrams show that the granitoids identified in the Pouni zone were emplaced in an active tectonic context, similar to that of present-day subduction zones.

LEO大型载人航天器主动电位控制技术进展

LEO大型载人航天器主动电位控制技术可以有效的防护空间等离子体充放电效应对于航天器造成的安全隐患,确保航天员出舱和航天器空间对接作业的顺利完成。通过研究LEO大型载人航天器与空间等离子体的相互作用,从原理上认识空间等离子体对于航天器的危害程度。分析回顾国外主动电位控制技术在LEO大型载人航天器上的成功应用及发展情况,得出启示和初步的主动电位控制系统设计设想。对比国内外主动电位控制领域的核心技术,对主动电位控制技术的发展和应用提出了建议。

载人航天天基测控通信探析

梳理了国内外空间站天基测控通信应用的概况,针对近地载人航天对测控通信系统的高要求,分析提出中继卫星系统的发展建议,以及导航卫星和低轨卫星星座系统的特点优势。调整中继卫星轨位、增加中继激光链路、采用全景波束全时监控模式,以及导航卫星和低轨卫星星座作为必要补充等途径,可为载人航天测控通信提供更好的灵活性、可用性和效费比。为载人航天天基测控通信发展提供了参考依据。

利比里亚金矿成矿地质背景与资源潜力

西非地区比里姆(Birimian)岩系经历了伊本尼(Eburnean)造山运动,成为全球金矿商业投资的主要含矿岩系之一,该岩系在利比里亚覆盖约36%国土面积。通过对西非尤其是利比里亚地质背景分析,初步建立了利比里亚区域地质构造格架,梳理出比里姆岩系中33处重要意义的岩金矿点,其分布与比里姆绿岩带、区域剪切构造带密切相关。综合全国266处金矿化点及密切相关的Au、Ag、Hg、Cu元素异常,在利比里亚划定了比-克波、杜格贝、塞斯托斯、鲍特洛-祖亚-皮菲吉、邦-托托-宁巴、杜贝、朱亚松、托迪8个金成矿带,显示出良好的成矿潜力,并对不同开发程度下矿化前景区进一步找矿方面提出了初步建议。

利用重复使用地月转移级往返近地轨道空间站的载人月球探测飞行模式

为提高中国月球探测的安全性和效费比,提出了一种利用重复使用地月转移级往返近地轨道空间站进行载人月球探测的任务模式,分析了任务往返的轨道和窗口,通过多方案对比分析给出2种构型重复使用地月转移级方案建议,估算对比了重复使用地月转移级效益,得出对于长期多次载人月球探测任务,采用重复使用地月转移级方案将具有更低的任务成本。

模拟载人探月中航天员空间辐射风险评估

空间辐射是长期载人航天飞行任务中影响航天员健康的重要风险因素。为了探求载人探月过程中对空间辐射的合理防护方式,文章借助空间辐射场模型对"嫦娥三号"飞行任务在不同质量厚度材料屏蔽下的舱内空间辐射环境进行了仿真计算,并确定了航天员各器官接受的空间辐射剂量、剂量当量以及有效剂量等辐射防护量以进行辐射风险评估。结果表明,随着屏蔽厚度的增加,航天员的各组织或器官的吸收剂量和剂量当量以及有效剂量均明显降低;采用质量屏蔽的方法对低于100 Me V的质子具有很好的防护效果,但对高能质子或重离子的防护效果不明显。计算和分析显示,载人探月过程中,只要采取适当的防护措施,航天员的空间辐射风险是可控的。

载人航天器舱内辐射环境及剂量分析

构建载人航天器模型,利用Geant4软件计算了银河宇宙射线中的质子穿过载人航天器后在水模体中的总吸收剂量以及次级粒子吸收剂量,并且统计了不同种类的次级粒子在水模体中的总数量分布。计算结果表明,次级粒子引起的辐射剂量所占比例为50%,且二次电子总数量达到了10~7量级。

载人航天器空间碎片防护与减缓设计

为降低空间碎片撞击所带来的威胁,文章针对某载人航天器进行了空间碎片撞击风险分析,并设计了空间碎片专用防护结构,制定了轨道规避策略;同时针对重点设备进行钝化设计,并采用寿命末期有控离轨制动方案。以上措施可有效实现空间碎片减缓。

载人航天微型磁等离子体辐射防护地面实验

星际飞行中的辐射主动防护问题一直是人们研究的焦点,低地轨道飞行中采用的质量厚度屏蔽已经不能满足要求,必须寻找新的空间辐射主动防护技术和方法。在电场、磁场、等离子体膨胀等众多新的主动防护方法中,选取了等离子体膨胀辐射防护技术作为研究对象;通过注入高能等离子体使磁场膨胀,从而使空间带电粒子偏转以减少空间辐射对飞行器及航天员的辐射损伤。通过原理性实验,证明了在真空状态下,等离子体的注入可以引起周围磁场发生变化,且同一个点的磁感强度随着射频电源输入功率的增大而增大。其机理还有待进一步的研究。

一种基于互联网星座的载人飞船测控模式构想

在总结神舟载人飞船测控模式发展演进规律的基础上,基于当前国内外低轨卫星星座蓬勃发展的趋势,文章提出了一种基于低轨互联网星座进行载人飞船测控的模式构想,通过对初步互联网星座方案构想下开展神舟载人飞船测控能力的仿真分析,得出该测控模式可将飞船最长站外时间降低至2 min,大幅提升应急处理能力和测控系统冗余,减少传统地面测站和中继资源占用,从而降低测控成本,提高测控效益,是未来测控模式演进的选择之一。

莱奥波尔德的大地伦理思想及启示

随着生态危机的加剧,人们环境保护意识的提高,人与自然的关系重新被审视。美国著名的生态伦理学家莱奥波尔德是环境保护主义思想的先驱,他所创立的大地伦理学是当今生态伦理学中主要流派。大地伦理思想把人与自然当作一个整体来思考,改变了传统的认知观念,确立了新的价值尺度,旨在构建一个和谐、美丽和稳定的大地共同体,为我们当代社会提供了理论指南与行动指导。通过分析莱奥波尔德的大地伦理思想,分析了大地伦理学对构建生态文明的启示,呼吁人们应重视生态问题,并加强对这一问题的研究,促进这一问题的解决,实现人与自然的和谐相处。

基于三菱FX3U系列PLC的盾构电气控制系统设计

为提高盾构的控制效果和自动化水平,搭建了以三菱FX3U系列PLC为控制核心的盾构控制系统。对PLC的I/O进行配置并设计了相应的控制电路和动力电路,根据设计的硬件电路进行下位机软件的编程和上位机人机界面的开发,制作了动力柜、控制柜和操作台实物。实验结果表明,设计的盾构电气控制系统能够控制刀盘正反转、螺旋机正反转,推进油缸伸缩以及各自的调速,实现对各个数据的处理、采集、报警等一系列功能,达到了预期效果,证明了所设计系统的可行性。

盾构施工人工测量与自动测量技术探讨

介绍了上海市轨道交通12号线顾戴路-东兰路区间φ6.34 m土压平衡盾构在2.1 km的掘进的过程中,为确保隧道顺利贯通,指导盾构沿设计轴线推进,所采用的人工测量与自动测量的方法及原理。在国内盾构法施工中,盾构机的导向既有人工测量方法,也有自动导向方法。具体施工过程中两套测量系统、相互校核,不断修正,主要相互验证测量数据计算的准确性和测量仪器的误差。

载人深空探索中空间辐射防护技术的研究进展

空间辐射防护是载人深空探索任务中降低航天员的空间辐射损伤和致病风险,确保航天员健康与安全的重要保障措施.然而,由于空间辐射环境的独特性与复杂性,目前的辐射防护技术面临着一系列的问题与挑战.本文在分析载人深空探索任务中空间辐射环境特点的基础上,系统综述了空间辐射防护技术中物理防护和生物医学防护技术的研究进展,提出了深空探索任务中空间辐射防护研究涉及的关键技术问题以及后续开展深入研究的一些设想,可为载人深空探索任务的实施提供参考与借鉴.

施特劳斯论霍布斯政治哲学的基础

一般认为,施特劳斯对霍布斯政治哲学基础的解读,重点在其早期著作《霍布斯的政治哲学》(1936)。实际上,《论霍布斯政治哲学的基础》(1954)一文才是最终的真正解读。其中,施特劳斯重新阐释了霍布斯政治哲学的基础。首先,霍布斯不再从自然欲望与自然理性的区分而是从具有因果判断这种特殊官能来定义人的特性。其次,霍布斯的政治哲学不是独立于而是依赖其对自然科学的理解。最后,霍布斯的不信仰是其政治哲学的必要前提。总而言之,霍布斯政治哲学的基础并不是霍布斯的人生观,而是霍布斯的整全观——霍布斯关于人、自然和神的全部观念。