Structural characteristics and tectonic division of the Zambezi Delta basin in the offshore East Africa:evidences from gravity and seismic data

The Zambezi Delta basin is a passive marginal basin located on the East African coast that has good oil and gas exploration potential.Due to the special geological evolutionary background of the Beira High in the Zambezi Delta basin,it has a low gravity anomaly,and the existing seismic survey lines do not cover the whole basin;therefore,it is difficult to interpret the structural characteristics of the whole basin based solely on gravity or seismic data.Based on satellite altimetry gravity anomaly data,this study infers the distribution characteristics of faults in the Zambezi Delta basin by using the normalized vertical derivative of the total horizontal derivative(NVDR-THDR)technique.Then,constrained by seismic data,the gravity anomaly at the Moho interface is extracted by using the fast forward method of the double-interface model of the gravity anomaly,and this anomaly is then removed from the Bouguer gravity anomaly to obtain the sedimentary layer gravity anomaly.The thickness of the sedimentary strata is obtained by inversing the sedimentary basement depth of the whole basin.Then,uplifts and depressions are divided based on a sedimentary layer thickness of 3 km.This research demonstrates that the Zambezi Delta basin mainly features nearly SN-trending and NE-trending faults and that these faults exhibit east-west partitioning.The nearly SN-trending strike-slip faults controlled the sedimentary development of the basin,and the NE-trending tensile faults may have acted as migration channels for oil,gas and magma.The“overcompensation”effect of the Moho interface gravity anomaly on the gravity anomaly of the sedimentary layer is caused by the depression of the Moho interface beneath the Beira High,which results in a low gravity anomaly value for the Beira High.The pattern of uplifts and depressions trends NE and has the structural characteristics of east-west blocks.

Regional Geochemical Division—A Tool for Delineating Geochemical Block

Regional geochemical division is a mapping technique to divide an area into slices where the associations between geochemical elements are relatively simple and uniform. The result of division is expressed on a 2 D map. The scheme of regional geochemical division includes non supervised pattern recognition, elementary statistics and factor analysis. A practical example in a gold prospecting area in Jilin, China, and the corresponding explanation are presented. Regional geochemical division is a basic approach to the delineation of the geochemical blocks as well.

Uplink Grant-Free Pattern Division Multiple Access (GF-PDMA) for 5G Radio Access

Massive machine type communication(m MTC) is one of the key application scenarios for the fifth generation mobile communication(5 G). Grant-free(GF) transmission can reduce the high signaling overhead in m MTC. Non-orthogonal multiple access(NMA) can support more users for m MTC than orthogonal frequency division multiple access(OFDMA). Applying GF transmission in NMA system becomes an active topic recently. The in-depth study on applying GF transmission in pattern division multiple access(PDMA), a competitive candidate scheme of NMA, is investigated in this paper. The definition, latency and allocation of resource and transmission mechanism for GF-PDMA are discussed in detail. The link-level and system-level evaluations are provided to verify the analysis. The analysis and simulation results demonstrate that the proposed GF-PDMA has lower latency than grant based PDMA(GB-PDMA), possesses strong scalability to confront collision and provides almost 2.15 times gain over GF-OFDMA in terms of supporting the number of active users in the system.

POPULATION MOVEMENT AND THE CHANGE OF REGIONAL ECONOMY PATTERN

Population movement is an important phenomenon in China in recent years. Its mechanism is: (1) thrust of more people and less land in the eastern region of China; (2) attraction of dual economy in the western region of China; (3) national policy on preferential wages and grains for the western region. Population movement has an important effect on the change of regional division pattern in China: by the medium of the moving people, there forms another regional division pattern, i.e. rural industry system based on rural town industry; (2) there forms another profit mechanism compensated from the western region to the eastern region. It not only wins more profit in the eastern region, but also changes dual economy in the western region. Therefore, We should make choice of a comprehensible and encouraging attitude on population movement; a special government organization for general survey of the moving people should be set up at once.

Quantitative division of succession and spatial patterns among different stand developmental stages in Changbai Mountains

Broadleaf-Korean pine forests exhibit high species richness and distinctive species composition, which are currently becoming more dominant among natural forests in Changbai Mountains of northeastern China. Understanding the ecological process of restored vegetation is quite important for ecosystem reconstruction. Distinguishing stand development stages and analyzing the dynamic spatial patterns could provide insights into significant community coexistence mechanisms. In the present study, eight permanent study areas were established according to the substituting space for time method in Changbai Mountains of north-eastern China. The optimal division method was used to quantify the successional series into different stand development stages, and the point pattern analysis method(L(r) function) was used to analyse the dynamic changes in spatial patterns and interspecific associations. Our results suggested that:(1) The stand development process was divided into five stages: the first three stages were poplar-birch secondary forests in different stages of recovery, the fourth stage was thespruce-fir mixed forest, and the last stage was the primary broadleaf-Korean pine forest;(2) The spatial pattern showed an aggregated distribution at a small scale and changed to a random distribution as the scale increased in poplar-birch secondary forests, but the spatial pattern appeared to be randomly distributed in spruce-fir mixed forest and broadleafKorean pine forest;(3) The interspecific associations between pioneer species and climax species changed from negative to positive among the different stand stages, and environmental resources were shared among these species. Interspecific differences in shade tolerance among the tree species were key determinants of forest dynamics and structure. Our study is vital to the understanding of the forest development;thus, the spatial change features should receive greater attention when forest management is being planned and restoration strategies are being developed for the Changbai Mountains.

Amphibian and reptilian distribution patterns in the transitional zone between the Euro-Siberian and Central Asia Subrealms

There exist some controversies over the larger zoogeographic divisions of the arid areas of Central Asia, whose characteristics include complex ecological environments, complex fauna origins and unique patterns of animal distribution. The aim of this study was to determine, using quantitative analysis, the distribution patterns of amphibians and reptiles in the arid areas of Central Asia, whose various physiographical regions were divided into 17 Operative Geographical Units （OGUs）. Based on the presence or absence of 52 amphibian and reptile genera in the 17 OGUs, and by making use of the Czekanowski Similarity Index, the Baroni-Urbani and Buser＇s Similarity Index, and the strong and weak boundary test, we studied the biotic boundaries within these contested regions. In accordance with our results, the classification dendrogram was divided into two main branches. One branch is composed of the northern OGUs of the Altai Mountains which are a part of the Euro-Siberian Subrealm. The other branch includes all of the OGUs south of the Altai Mountains, which belong to the Central Asia Subrealm. There is a significantly weak biotic boundary （DW〉0, GW〉GS, P〈0.01） between the Euro-Siberian Subrealm and the Central Asia Subrealm that corre- sponded to the transitional zones. The boundary between the two subrealms runs along the Altai Mountains, the Sayan Mountains, the Hangai Mountains and the Mongolian Dagurr Mountains. The boundaries between the main branches in the Central Asia Subrealm are weak, reflecting the widespread existence of transitional zones in the arid areas of Central Asia. The Tianshan Mountains should be elevated to form its own separate region, ＂the Middle Asian Mountain Region＂, which, due to its special fauna and environment, would be classified at the same level as the Mongolia-Xinjiang Region. With the approach of creating a cluster analysis dendogram based upon the genera of amphibians and reptiles, the relationship of these higher level zoogeographical divisions was successfully resolved and the error of long-branch attraction was also avoided. With our clustering dendrogram as the foundation, the in- dependence test was applied to strong and weak boundaries, and this resolved the problem of where to attribute the transition areas and revealed as well the barrier effect that physical, geographic boundaries have upon amphibians and reptiles. The approach of combining genera clustering analysis with a statistical boundary test should be applicable not only to the distribution patterns of other animal groups, but also to delineating large-scale zoogeographical divisions.

Division of Free Nuclei in Rice Endosperm and Its Influencing Factors

The division process of endosperm in rice and its influencing factors were investigated. Total dissection, resin embedding and sectioning under light and transmission electron microscopes were used to observe the division patterns of free nuclei and cytological characters of an endosperm. The various division patterns of free nuclei in rice endosperm included mitosis, amitosis, and the mitosis to amitosis change without an interphase. The division velocity of free nuclei in rice endosperm varied with the internucleus distance. Comparing to a cluster, the division velocity increased when the free nuclei were separated from each other. Moderately higher temperatures also enhanced the proliferation and shortened the division cycle of free nuclei in rice endosperm. To a certain extent, nitrogenous fertilizer applied at the booting stage together with a moderate drought treatment accelerated the division of free nuclei as well.

城市地区场次降雨时空展布方法研究

受气候变化和城市规模不断扩张等因素影响,城市地区降雨过程的时空动态性愈发明显,通常采用的点、面雨量等表达方式难以体现这种时空动态性。随着降雨观测技术的进步,大多城市积累了长序列降雨观测数据,其中蕴含了丰富的降雨时空过程信息,为预报降雨或设计降雨的时空展布提供了可能。设计了一套降雨时空展布方法,包括数据收集、标准化处理、降雨场次划分、时空模式提取、标准网格插值、时空展布等环节,并提出每个环节的处理步骤和关键问题。以北京市为例,对该技术方法进行了验证,选择了12 h、24 h、72 h 3个历时的场次降雨,提取的时空模式和展布结果表达出了场次降雨的时空动态性,并与历史的降雨过程表现出很好的匹配性。表明该方法可用于城市地区降雨典型模式提取,以及降雨过程的时空展布。该方法利用历史降雨数据提取降雨展布模板,输入场次降雨(或预报降雨)的总雨量,得到该场次降雨的时空分布过程,展布结果可为洪水预报提供更为准确的降雨输入条件。

全球铝土矿贸易格局演化及中国贸易特征

我国铝土矿资源供给长期难以满足需求,需要从海外进口大量的优质铝土矿来满足国内需求。为了研究经济政策等要素对铝土矿国际贸易格局的影响,以2012—2022年全球铝土矿贸易额作为数据来源,运用复杂网络分析方法,构建了铝土矿贸易随机网络和加权网络,对全球铝土矿贸易格局演变、主要贸易国地位演变和中国铝土矿贸易网络特征进行研究。结果表明:(1)全球铝土矿贸易网络规模具有稳健性,但其贸易网络结构具有不对称性,国家之间的贸易联系较为分散,全球铝土矿贸易呈碎片化特征。(2)全球铝土矿贸易国家中,澳大利亚与中国分别为出入强度最大的国家,但二者中介控制能力均有待加强,印度的中介控制能力较强,起到“桥梁”的作用。(3)中国是全球第一大铝土矿进口国,出口贸易额排名也不断上升,且进出口市场格局均较为集中。未来中国扩大铝土矿进口市场格局,潜在可选范围较为广泛:一方面中国仍然可以继续对澳大利亚、印度尼西亚、巴西和圭亚那等传统贸易国家加大进口份额;另一方面,中国可以利用地缘优势加强对土耳其、印度等“一带一路”沿线国家的铝土矿进口。

地区异质性、区际分工优化与加快构建新发展格局

地区异质性是区际分工优化的原因。区际分工优化即围绕地区主体功能定位进行分工优化,在很大程度上是地区异质性的结果。二者共同决定一个地区在构建新发展格局中如何定位、如何分工、如何强化优势以融入和服务新发展格局。在推进高水平对外开放、优化区域开放布局的过程中,内陆及沿边地区的对外开放给这些地区“第一自然”的“再发现”提供了可能,也为“第二自然”的“再创造”营造了制度友好型的发展环境,有利于我国经济地理的重塑。同时,各地区应以发挥比较优势为出发点,选择发展方向和主导产业,在区际分工体系中发挥独特作用,参与全国产业链的打造,积极融入和服务构建新发展格局,为国家建设具有完整性、先进性、安全性的现代化产业体系贡献各自力量。此外,只有打破市场分割,打通经济循环的生产、分配、流通、消费各环节堵点,建设全国统一大市场,发挥各地区比较优势生产出来的产品才可能有相对一个地区而言大得多的市场。全国统一大市场是一个需求主体广大的、边界不断扩展的统一大市场。可见,建设全国统一大市场,会不断释放统一市场的制度红利,不断拓展可促进区际分工优化的内需潜力,进而有助于各地区积极融入和服务构建新发展格局。

面向用户需求的低轨卫星资源分配算法

低轨(LEO)卫星多波束通信场景下,传统固定资源分配算法无法满足不同用户对信道容量的差异需求。以适应用户需求分配为主要目标,建立联合信道分配、带宽分配和功率分配的最小供需差优化模型,并引入图样分割多址接入技术(PDMA)提升信道资源的利用率。针对该模型的非凸特性,通过Q-learning算法学习资源分配最优策略为每个用户分配适合的信道容量,并引入奖励阈值进一步改进算法,加快算法的收敛,且使算法达到收敛时供需差异更小。仿真结果表明,改进后的算法收敛速度约是改进前的3.33倍:改进算法能满足更大的用户需求,比改进前Qlearning算法提升14%,是传统固定算法的2.14倍。

上海市双职工育儿家庭的时间压力与分工特征

双职工家庭在育儿阶段遭遇的多重时间压力,是我国城市居民家庭面临的主要困境之一,已引起社会的广泛关注与讨论。然而,针对这一问题的实证研究仍十分匮乏。基于上海2018年时间利用调查数据,分析了双职工育儿夫妻的时间利用特征,剖析了夫妻的时间压力类型及其日常活动特征,并探讨了不同时间压力类型的家庭分工方案。研究发现,双职工家庭在育儿阶段遭遇家务照料与通勤时间增加的双重压力;识别出超高家庭压力型、家庭压力型、通勤压力型、一般压力型4种时间压力类型等。以期揭示我国大城市典型家庭的生活困境,为家庭与育儿友好的政策制定提供研究基础与启示。

港口岸电系统冲击性负荷功率柔性控制方法

为解决港口岸电系统中负荷功率存在较强冲击性问题,提出一种基于储能电池的负荷功率柔性控制方法,在实现功率实时平抑和无功动态补偿的基础上,降低系统网侧线损、提升储能电池循环寿命及应对极端工况的能力。首先,介绍负荷功率柔性控制系统(load power flexible control system,LPFCS)的拓扑结构及控制方式;其次,依据负荷功率和电池荷电状态来划分负荷工况,进而以负荷功率波动的平抑、防止电池过充过放以及提升储能系统应对极端工况的能力为原则,将LPFCS的工作模式分为空闲、填谷、削峰以及限幅4种模式;然后,建立系统网侧线损优化模型,求解模型得出功率补偿值的取值区间,并基于该区间确定不同工况下LPFCS的功率补偿值。最后,基于长江某岸电系统实测负荷数据,对LPFCS的工作性能进行仿真和实验验证。结果表明:LPFCS的补偿响应时间小于0.3 s,负荷功率波动抑制率达到90%,系统网侧线损率下降17.2%。

淮北煤田钱营孜矿井控煤构造特征及其动力学背景分析

钱营孜矿井位于淮北煤田宿县矿区的西部,毗邻徐宿弧形推覆构造南段的外缘带。为认识该矿井构造变形与演化规律、动力学机制以及指导未来资源探采方向提供重要地质依据。利用最新的矿井地质勘探与生产资料,对钱营孜矿井开展构造格架和控煤构造样式分析,划分矿井构造期次,讨论构造发育的区域大地构造背景。结果表明,矿井内石炭纪-二叠纪含煤地层总体呈一轴向NNE、向SSW仰起的宽缓向斜;矿井内断裂构造非常发育,逆断层数量大于正断层,2类断层的走向均以NE至NNE向为主,其次为NS向;矿井构造格架显著受控于数条NS向至NE向的大型断层,自西向东受南坪断层、F_(22)、F_(17)、DF_(200)及双堆断层等主干断层的分割,呈现东、西分带特征;矿井控煤构造样式可以划分为挤压、伸展和走滑3个类型,以及逆冲牵引褶皱、对冲式构造、冲起构造、叠瓦状构造、地堑、地垒、阶梯状断层、正花状构造、羽状雁列式构造9个亚类型;构造组合分析表明,F_(17)断层除逆冲活动之外,还存在显著的平移活动。矿井构造可划分为5期,从早到晚分别为:轴向NNE的冯家向斜、近NS向逆断层、NNE向逆-左行平移断层及NE向逆断层、近NS向正断层、NE向正断层。矿井内第1,2期缩短构造分别是印支期华北克拉通与华南板块汇聚过程中的前陆变形及随后陆-陆碰撞造山变形的影响结果;第3期压扭性构造与西太平洋区伊泽奈崎板块早白垩世初向东亚大陆边缘快速斜向俯冲有关;第4,5期伸展构造则是早白垩世以来中国东部强烈伸展背景下发育而成。

塔里木盆地塔河油田T738井区一间房组高精度层序地层格架内沉积微相特征

塔河油田T738井区一间房组地质年代老、埋藏深度大,虽经历了复杂的构造与成岩改造,但仍具有良好的储集性能。目前该井区重点勘探开发主要集中在断裂带发育部位,以断溶体为主要钻探目标。然而,礁滩相勘探潜力巨大,但是对影响碳酸盐岩礁滩相储层发育沉积相认识的不足制约了勘探突破。本研究基于塔河油田T738井区重点井钻测井资料的分析和薄片鉴定工作,建立了T738井区一间房组高精度层序地层格架,总结了一间房组开阔台地内沉积微相常规测井相模式,对沉积微相类型和特征分别进行了划分和描述,分析了四级层序内部礁滩体厚度分布和沉积微相平面展布特征。结果显示,一间房组划分为1个三级层序(Sq1)和3个四级层序(Ssq1、Ssq2和Ssq3),在开阔台地相识别出高-中-低能滩、丘滩间、生物礁(丘)等几种沉积微相。其中,颗粒滩在常规测井判别值域分别对应AC为51~61μs/m,DEN为2.5~2.6 g/cm^(3),CNL为1%~6%,RD为80~3000Ω·m。一间房组Ssq1层序礁滩体规模较小且孤立,仅分布在地势相对高部位,归因于其在三级层序内所处的海侵体系域低部位,水动力条件较弱。Ssq2、Ssq3层序礁滩体位于三级层序内高位体系域,其规模较大、连片性较好,厚度稳定,最大累计厚度达40 m。

海绵城市视角下湖北省年径流总量控制空间格局研究

年径流总量控制率是海绵城市规划建设的首要指标,与之相对应的设计降雨量是海绵城市规划设计的重要依据,年径流总量控制率与设计降雨量的对应关系是海绵城市规划建设的关键问题。该文利用湖北省39个设市地市(含神农架林区)30年的水文降雨资料,研究得出湖北省年径流总量控制率与设计降雨量的对应关系,形成了湖北省年径流总量控制目标一览表和湖北省年径流总量控制率区域划分一张图,结果表明:(1)湖北省年径流总量控制率分为3个区,分别对应中国内地地区年径流总量控制率分区图的Ⅱ区(80%≤α≤85%)、Ⅲ区(75%≤α≤85%)和Ⅳ区(70%≤α≤85%),设计降雨量范围分别为Ⅱ区(10 mm≤H≤28.3 mm)、Ⅲ区(12.7mm≤H≤39.5 mm)、Ⅳ区(14.3 mm≤H≤49.0 mm);(2)神农架、丹江口、十堰等处于Ⅱ区,襄阳、利川、宣恩等处于Ⅲ区,随州、天门、咸宁、黄石、孝感、仙桃、黄冈、鄂州、武汉等处于Ⅳ区。研究填补了湖北省各城市年径流总量控制指标的空白,相关取值建议有助于推进全省海绵城市规划与建设工作。

PatU3 plays a central role in coordinating cell division and differentiation in pattern formation of filamentous cyanobacterium Nostoc sp.PCC 7120

Spatial periodic signal for cell differentiation in some multicellular organisms is generated according to Turing's principle for pattern formation.How a dividing cell responds to the signal of differentiation is addressed with the filamentous cyanobacterium Nostoc sp.PCC 7120,which forms the patterned distribution of heterocysts.We show that differentiation of a dividing cell was delayed until its division was completed and only one daughter cell became heterocyst.A mutant of patU3,which encodes an inhibitor of heterocyst formation,showed no such delay and formed heterocyst pairs from the daughter cells of cell division or dumbbell-shaped heterocysts from the cells undergoing cytokinesis.The patA mutant,which forms heterocysts only at the filament ends,restored intercalary heterocysts by a single nucleotide mutation of patU3,and double mutants of patU3/patA and patU3/hetF had the phenotypes of the patU3 mutant.We provide evidence that HetF,which can degrade PatU3,is recruited to cell divisome through its C-terminal domain.A HetF mutant with its N-terminal peptidase domain but lacking the C-terminal domain could not prevent the formation of heterocyst pairs,suggesting that the divisome recruitment of HetF is needed to sequester HetF for the delay of differentiation in dividing cells.Our study demonstrates that PatU3 plays a key role in celldivision coupled control of differentiation.

市场转向与专业化分工——以中国出口导向型制造企业为例

自2008年金融危机以来,中国出口导向型制造企业出现了以出口为主转向出口和内销并重的趋势,尤其在双循环新发展格局背景下,这一趋势更加明显。然而现有文献很少关注企业市场转向后的行为。本文基于企业分工的视角,以2009~2022年中国出口导向型制造企业为样本,实证研究了市场转向驱动企业专业化发展的内在机理和边界条件。研究发现:市场转向显著提升了中国出口导向型制造企业专业化分工水平,并且该结论在考虑内生性问题及一系列稳健性检验后仍然成立;机制分析表明,市场转向对企业专业化分工的促进作用主要通过降低企业面临的外部交易成本来实现;市场转向对企业专业化分工的影响具有明显的异质性,在国有企业、规模较大企业中促进效果更加明显;市场转向通过促进企业专业化分工提高了出口导向型制造企业全要素生产率和创新质量。本文研究结论对于双循环先发展格局政策制定具有重要的借鉴意义。

我国面板堆石坝内部变形监测技术发展综述

面板堆石坝内部变形是反映大坝填筑质量、选择面板浇筑时机、评价大坝整体运行状态的关键指标,是工程参建各方关注的焦点。本文系统归纳了面板堆石坝内部变形监测技术的发展现状,并结合实际工程应用效果分析了各类监测技术存在的主要问题,对未来堆石体内部变形监测技术的发展提出了几点思考,以期为我国面板堆石坝安全监测技术的发展发挥积极作用。

国土空间背景下村庄发展潜力及类型划分研究——以云南省石屏县为例

在国土空间背景下,村庄发展水平的精准识别和村庄的合理分类是乡村振兴的前提和基础,有利于揭示县域乡村的空间差异性。本文以石屏县为例,以建制村为基本单元,构建VCM模型对村庄初步分类;借助ArcGIS综合评估之后,从村庄区位条件、资源禀赋、村庄治理、发展基础、生态环境等五个维度构建村庄发展潜力模型,明确村庄发展类型,揭示空间特征,保障乡村振兴战略的实施和国土空间规划的落实。研究表明,石屏县村庄发展潜力呈现“中部高、南北低”的差异性格局,由此将115个村划分为3大类10小类的村庄发展类型,结合实际情况提出相应的发展策略。