Vertical marginal gap &retention of ceramic full coverage &inlay retained ceramic fixed partial dentures

Objectives: A comparison study between ceramic full coverage FPDs & 3 designs of ceramic inlay retained FPDs regarding vertical marginal gap & retention. Materials & Methods: Twenty samples were construc- ted and divided into 4 groups according to the type of restorations: full coverage, inlay-shaped (occluso-pro- ximal inlay + proximal box), tub-shaped (occluso-pro- ximal inlay), and proximal box-shaped FPDs. All samples were subjected to a vertical marginal gap measurements followed by a retention test. Results: The vertical marginal gap data showed no significant difference between full coverage FPDs, the tub-shap- ed inlay retained FPDs and the proximal box-shaped inlay retained FPDs. While there was a difference between these three designs and the inlay retained FPDs. Regarding retention, the full coverage FPDs recorded higher retentive strengths and was signifi-cant difference than all inlay retained FPDs designs tested. The inlay-shaped design was significant dif-ference than the other two inlay retained FPDs de-signs. Conclusions: There was no significant differ- ence between full coverage FPDs, tub-shaped & pro- ximal box shaped inlay retained FPDs as regard ver- tical marginal discrepancies. While, the inlay-haped design showed the highest vertical marginal discrep- ancies. The premolar & molar retainers for the same type of restorations showed no difference in vertical marginal discrepancies. All measured vertical mar- ginal discrepancies were in the range of clinical ac- ceptance. The full coverage FPDs recorded higher retentive strengths than all inlay retained FPDs de- signs tested. The inlay-shaped design recorded the highest retentive strengths among the three inlay re- tained FPDs designs. There was no difference as re- gard retentive strengths between tub-shaped & pro- ximal box shaped inlay retained FPDs.

GLOBAL LINEAR AND QUADRATIC ONE-STEP SMOOTHING NEWTON METHOD FOR VERTICAL LINEAR COMPLEMENTARITY PROBLEMS

A one_step smoothing Newton method is proposed for solving the vertical linear complementarity problem based on the so_called aggregation function. The proposed algorithm has the following good features: (ⅰ) It solves only one linear system of equations and does only one line search at each iteration; (ⅱ) It is well_defined for the vertical linear complementarity problem with vertical block P 0 matrix and any accumulation point of iteration sequence is its solution.Moreover, the iteration sequence is bounded for the vertical linear complementarity problem with vertical block P 0+R 0 matrix; (ⅲ) It has both global linear and local quadratic convergence without strict complementarity. Many existing smoothing Newton methods do not have the property (ⅲ).

Slab window magmatism and convergent margin tectonics

1. Introduction The convergence plate margins, where lithospheric plates move each other and collide, are the most intense areas of magmatism, tectonism and metamorphism. The development of slab windows beneath convergent margins, originally defined by Dickinson and Snyder （1979）, is one of the essential mechanisms of subduction- related tectonics. A slab window is a gap that forms in a subducting plate when a mid-oceanic ridge reaches a trench and is subducted. The opening of a slab window causes various geological processes including magmatism （e.g. Thorkelson, 1996; Kinoshita, 2002; Bradley et al., 2003; Thorkelson and Breitsprecher, 2005; Zhang et al., 2010; Eyuboglu et al., 2011a）, changes in plate kinematics and deformation （Hibhard and Karig, 1990）, mineralization （Haeussler et al., 1995; Eyuboglu et al., 2011b）, high temperature metamorphism （Sisson et al., 1989; Santosh and Kusky, 2010）, and changes in sedimentary basin evolution （Dostal et al., 2001; Wilson et al., 2005）. In this special issue of Geoscience Frontiers （GSF）, I assemble a set of contributions on the current understanding of petrogenesis of slab window-related arc magmas and also convergent margin tectonics.

陕西三次强致灾性初夏区域性暴雨动力诊断对比分析

利用常规气象观测资料和0.25°×0.25°逐小时ERA5再分析资料,对综合评价强度指数300以上的三次陕西初夏区域性暴雨过程从水汽、动力垂直结构上进行对比分析。结果表明:①强致灾性初夏区域性暴雨发生前,中高层水汽输送来自西南气流,低层来自偏东气流,低层水汽辐合发展加强,动力强迫主要表现为700 hPa以下正涡度区发展加强并向高层延伸,对应200 hPa附近出现强负涡度中心;②暴雨开始后,低层偏东水汽输送在暴雨过程中会发生变化,水汽辐合持续加强并向高层持续输送,散度场出现低层强辐合、高层辐散的结构,而关中有双重辐合-辐散特殊结构,且正涡度区继续向高层延伸、动力抬升促使上升运动延伸至400 hPa及以上;③初夏暴雨陕南动力强迫相比关中较弱,但水汽输送、水汽含量比关中好,降水效率更高、降水总量更大。

俯冲侵蚀的研究历史、现状与展望

俯冲侵蚀是指在板块俯冲过程中,俯冲板块通过构造作用移走俯冲上盘的物质并将其带到深部地幔的过程。前人研究表明,俯冲侵蚀在新生代环太平洋俯冲带是一种十分普遍且非常重要的地质过程,同时对活动陆缘的构造变形、岩浆弧的形成、金属成矿、壳-幔物质循环以及大陆地壳的生长与演化均具有重要的影响。本文在回顾前人研究历史的基础上,简要介绍了俯冲侵蚀的基本模型和控制因素,系统总结了俯冲侵蚀引起的地质效应以及识别依据,分析探讨了俯冲侵蚀与金属成矿、大陆地壳演化的关系。此外,本文还介绍了俯冲侵蚀在国内的研究现状,并分析了青藏高原的班公湖-怒江缝合带和雅鲁藏布江缝合带晚中生代俯冲侵蚀识别的研究实例,揭示了欧亚大陆南缘在晚中生代是一个侵蚀型的板块汇聚边界。最后对我国今后开展相关研究提出了一些思考和展望。

巴罗型变质作用的地质特征及其构造启示:以苏格兰高地和喜马拉雅造山带为例

巴罗型变质带是汇聚板块边缘富铝泥质岩在中等地温梯度下变质作用的产物,广泛分布于全球各造山带。虽然不同地区的巴罗型变质带具有相似的矿物组合和变质温压条件,但在特征矿物变质带的空间分布上却存在显著差别。苏格兰高地出露了典型的巴罗型变质带,而喜马拉雅造山带则出露了反转的巴罗型变质带。这两类巴罗型变质带记录了不同的变质和构造演化过程,是对比研究碰撞造山带温压结构和动力体制的时空演化及其地球动力学机制的天然实验室。本文以苏格兰高地和喜马拉雅造山带为例,比较了典型的巴罗型变质带和反转的巴罗型变质带的岩石学与年代学特征,并探讨了它们的形成机制。这两个地区的研究各具特色:苏格兰高地的研究主要聚焦于加热机制,强调软流圈地幔及其派生岩浆等外部热源对巴罗型变质带形成的关键作用;而喜马拉雅造山带的研究则主要关注构造过程,强调逆冲断层的顺序式活动对反转的巴罗型变质带形成的控制作用。进一步,本文将研究视角从巴罗型变质带拓展至巴罗型变质作用,综合考察其加热机制和构造背景,并探讨这对碰撞造山和地壳再造过程研究的启示。

The stability margin on EAST tokamak

The experimental advanced superconducting tokamak （EAST） is the first full superconducting tokamak with a D-shaped cross-sectional plasma presently in operation. Its poloidal coils are relatively far from the plasma due to the necessary thermal isolation from the superconducting magnets, which leads to relatively weaker coupling between plasma and poloidal field. This may cause more difficulties in controlling the vertical instability by using the poloidal coils. The measured growth rates of vertical stability are compared with theoretical calculations, based on a rigid plasma model. Poloidal beta and internal inductance are varied to investigate their effects on the stability margin by changing the values of parameters αn and γn（Howl et al 1992 Phys. Fluids B 4 1724）, with plasma shape fixed to be a configuration with k = 1.9 and 5 = 0.5. A number of ways of studying the stability margin are investigated. Among them, changing the values of parameters κ and li is shown to be the most effective way to increase the stability margin. Finally, a guideline of stability margin Ms（ki, li, A） to a new discharge scenario showing whether plasmas can be stabilized is also presented in this paper.

Current State of Strain in the Central Cascadia Margin Derived from Changes in Distance between GPS Stations

Using continuously operating Global Positioning Stations in the Pacific Northwest of the United States, over 100 station-station baseline length changes were determined along seven West-East transects, two North-South transects and in three localized areas to determine both the average annual strains over the past several years, and the variation in strain over the central Cascadia convergent margin. The North-South transects (composed of multiple baselines) show shortening. Along West-East transects some baselines show shortening and others extension. The direction of the principle strains calculated for two areas 100 km from the deformation front are close to per-pendicular to the deformation front. The North-South strains are 10?8 a?1, which is an order-of-magnitude less than the West-East strains (10?7 a?1). Along several West-East transects, the magnitude of the strain increases away from the deformation front. All West-East transects showed a change in strain 250 km inland from deformation front.

Current tectonic deformation and seismogenic characteristics along the northeast margin of Qinghai -Xizang block

Based on the data from repeated precise leveling and across-fault deformation measurements carried out in recent 30 years and the analyzed results from GPS observations made in recent years along the northeastern margin of Qinghai-Xizang block, and combined with the geological structures and seismic activities, some characteristics in regional tectonic deformation and strong earthquake development are studied and approached preliminarily. The results show that: a) The space-time distribution of current tectonic deformation in this area is inhomogeneous with relatively intensive tectonic deformation in the vicinity of main boundary faults and weak deformation in the farther areas. The intensity of vertical differential movement and the deformation status vary with time, and the horizontal movement and deformation are characterized by apparent compression and strike-slip. b) The tectonic stress field generated by the NE-trending continuous compressive movement of Qinghai-Xizang block due to the northward press and collision of India plate is the principal stress for the tectonic deformation and earthquake development in this area. The evolution of space-time distribution of tectonic deformation and seismicity is closely related to the block activity and dynamic evolution of regional tectonic stress field. c) The vertical deformation uplift and high-gradient deformation zones and the obvious fault deformation anomaly appeared along the boundaries of tectonic blocks can be considered as the indicators of hindered block motion and intensified tectonic stress field for strong earthquake development. Usually, the above-mentioned phenomena would be followed by the seismicity of M6.0, but the earthquake might not occur in the place with the maximum movement. The zones with the fault deformation anomaly characterized by tendencious accumulation acceleration turning and the surrounding areas might be the positions for accumulation of strain energy and development and occurrence of strong earthquakes.

Late Stage Interseismic Strain Interval, Cascadia Subduction Zone Margin, USA and Canada

Modern horizontal strain (2006-2016) measured along 56 new and 108 previously published GPS station baselines are used to establish the length (800 km) and width (300 - 400 km) of the central Cascadia convergent margin seismogenic structure. Across-margin (west-east) annual rates of shortening range from 10﹣9 a﹣1 at the eastern (landward) limit of the central Cascadia seismogenic structure to 10﹣7 a﹣1 along the western onshore portion of the interplate zone. Relatively high shortening strain rates (10﹣8 a﹣1 to 10﹣7 a﹣1) are also measured in western transects from the northern (Explorer plate) and southern (Gorda plate) segments of the convergent margin, demonstrating that the full length of the margin (1300 km length) is currently capable of sustaining and/or initiating a major great earthquake. Vertical GPS velocities are averaged over the last decade at 321 stations to map patterns of uplift (0 - 5 mm yr﹣1) and subsidence (0 - 9 mm yr﹣1) relative to the study area mean. Along-margin belts of relative uplift and subsidence, respectively, are approximately associated with Coast Ranges and the Cascade volcanic arc. However, the vertical velocity data are locally heterogeneous, demonstrating patchy “anomalies” within the larger along-margin belts. A large coastal subsidence anomaly occurs in southwest Washington where the modern short-term trend is reversed from the long-term (~200 yr) tidal marsh record of coastal uplift since the last co-seismic subsidence event (AD1700). The modern vertical displacements represent a late stage of the current inter-seismic interval. If the horizontal strain is considered largely or fully elastic, extrapolating the modern strain rates over the last 100 years show the accumulated strains would be similar in magnitude to the observed co-seismic strains resulting from the Tōhoku, Japan, Mw 9.0 earthquake in 2011. We believe that the central Cascadia seismogenic structure has accumulated sufficient elastic strain energy, during the last 300 years, to yield a Mw 9.0 earthquake from a rupture of at least one-half (400 km) of its length.

2022年中国短视频发展报告

2022年,中国短视频行业在发展中不断沉淀,在新旧交替、开放合作中出现了新形态、新业态,用户结构逐渐走向全民化,行业格局逐步稳固;主流媒体短视频化与短视频平台主流化交互影响,助力主流舆论引导;短视频内容边界充分拓展,长短视频开放合作,微短剧发展步入新赛道;垂直细分纵深推进,场景建构凸显社会价值。与此同时,短视频行业进入存量维系后市场竞争加剧,用户层面未成年人短视频沉迷防范任务依旧艰巨;内容层面导向不良、审核机制有待完善;营收层面亟待挖掘增量与增效空间。未来的短视频发展,需要坚持内容为本、传播主流价值,重视用户需求并增强场景适配,充分利用技术赋能拓展行业布局。

Gravity evidence of underplating in the northeastern margin area of Qinghai-Tibet plateau

Based on leveling data in 1972 -2011 and relative-gravity data in 1993 -2011, we obtained a longterm vertical crustal-deformation rate of 1.62mm/a and a relative-gravity variation rate of 0.62 × 10^-8 ms^-2a^-1 for the northeastern margin area of Qinghai-Tibet plateau. After removing the contributions from the observed vertical movement and inferred surface denudation, we obtain a gravity-variation rate of 0.73 × 10^-8 ms^-2a^-1 attributable to the mass changes beneath the crust. This positive change suggests that the total mass under the observation stations was gradually increasing. We consider this result to be the gravitational evidence of underplating beneath the study area, and propose that the underplating was caused by collision betwen the Indian plate and Tibetan plateau and by gravitation-potential induced deviatoric stress.

中国产业高质量发展的测度及时空演进特征研究

产业高质量发展是中国改革开放以来经济高速成长的密码,也是构建新时期经济发展格局、实现经济高质量发展的基础。本文基于产业协调、产业融合和产业绿色发展3个维度构建了中国产业高质量发展指数,分析了2011~2021年产业高质量发展指数的时间演进特征、空间差异及其来源和收敛性。研究发现:中国产业高质量发展水平呈现明显的上升趋势,表现为东、中、西逐次递减的分布特征,增速则显示与排序相反的分布状态;产业高质量发展空间差异有明显的改善趋势,全国及东、西地区的基尼系数均呈现下降趋势,中部地区的基尼系数出现先下降后波动上升的演进态势;从东、中、西三大区域核密度曲线分布特征来看,东部和中部地区产业高质量发展水平总体上升,存在一定的极化趋势,但绝对差异逐步缩小;西部地区产业高质量发展整体上升,绝对差异有缩小态势,无极化现象;同时不同等级的地区具有较强的稳定性,降级和跃迁的可能性较小。

分布式驱动电动汽车附着稳定性控制

通过分析车轮垂向载荷转移对轮胎附着裕度的影响机理,制定一种直接横摆力矩控制策略以充分发挥车辆极限附着行驶能力。采用分层式控制结构,上层为附加横摆力矩决策层,运用模型预测控制算法求解所需的附加横摆力矩;下层为四轮转矩优化分配层,将上层求得的附加横摆力矩优化分配给各轮,以修正车身姿态。通过Matlab/Simulink与CarSim联合仿真测试和基于dSPACE LabBox驾驶模拟器台架的硬件在环实验,验证转矩分配方案的合理性与控制策略的有效性。实验结果表明:该策略有效改善了各轮附着利用情况,提高了车辆极限行驶能力与附着稳定性。

黄河流域绿色创新发展的时空分异及收敛检验--来自内蒙古沿黄生态经济带的经验发现

绿色创新是推动黄河流域生态保护和高质量发展的根本途径。基于2011-2020年内蒙古沿黄生态经济带绿色创新发展数据,采用Super-SBM模型,结合重心—标准差椭圆和Dagum基尼系数分析,揭示内蒙古沿黄生态经济带绿色创新发展的时空分异特征;利用变异系数、边际垂直β收敛模型探究绿色发展的收敛特征。研究表明:内蒙古沿黄生态经济带绿色创新发展态势向好,但稳定、可持续发展的绿色创新环境尚未形成;受资源禀赋限制,地区间绿色创新发展分化明显,蒙西地区内部差异显著;内蒙古沿黄生态经济带全区、蒙中地区的绿色创新发展存在显著的σ收敛与β收敛特征,蒙西地区收敛特征不稳定。提出内蒙古沿黄生态经济带绿色创新发展亟需加强绿色创新基础建设投入、差异化政策制定与绿色创新高水平收敛机制构建等,以推进黄河流域经济协同高质量发展进程。

煤炭行业产能过剩的再认识——基于潜类别随机边界法的测算及其空间演变

煤炭行业的产能过剩造成资源浪费,不利于绿色、高效、安全能源系统的发展。产能利用率是表征产能过剩程度的重要指标,对其客观科学测算有利于正确评判煤炭行业产能过剩的程度及其发展趋势,为有关部门产能政策制定和煤炭企业市场决策提供依据。我国煤炭资源分布的不均衡性以及埋藏地质差异决定了其开发利用的区域差异性,以往的测算方法忽略了此种差异对产能利用率的影响。本文采用潜类别随机边界法对我国24个产煤省2001—2017年煤炭行业产能利用率进行测算,基于开采条件的内生差异,将产煤省划分为丰富型、适度型、贫乏型和枯竭型4个群组,运用空间计量模型对各群组产能利用率的空间演变特征进行分析。研究结果表明:煤炭行业产能利用率在测算年度内呈现先上升后下降的趋势,平均水平为0.82;产能过剩情况在群组间存在较为明显的差异,贫乏型和枯竭型群组的生产已接近生产边界,产能利用率改善空间有限,适度型群组产能利用率的平均值为0.63,产能过剩较为严重;影响因素对各群组产能利用率的作用各异,总的来说,经济发展影响因素对煤炭产能利用率具有负向作用,但对资源丰富、技术先进、拥有多数大煤炭基地的丰富型群组具有正向作用,说明由经济增长而引发的扩张产能忽视了质量提升;产能利用率对市场需求的变化敏感,需求的增长有利于产能利用率的提升;煤炭行业产能利用率存在空间β条件收敛,说明产业转移有助于产能利用率的空间追赶,产能利用率总体水平提升,地区间差异缩小。由此可得,要实现煤炭产业的高质量发展,应加大西部和新兴生产基地的基础建设和科技投入,加速中部地区落后产能的退出和整合,发挥市场在煤炭产能优胜劣汰中的关键作用,积极引导贫乏型、枯竭型群组的人力和管理资源向丰富型、适度型群组转移。

2018—2022年成都汛期短时强降水时空分布特征

利用成都市2018—2022年汛期(5—9月)14个国家气象观测站逐小时降水资料,运用统计学方法和ArcGIS普通克里金插值法,对成都市短时强降水时空分布特征以及地形作用进行分析。结果表明:短时强降水频次年变化呈显著下降趋势;月变化呈单峰型,集中发生在7—8月,占汛期的77.3%,主峰在8月;夜间短时强降水频次高于白天,集中在01—07时,峰值出现在01-03时,夜雨特征明显,高值区位于彭州-都江堰-崇州-大邑-邛崃-蒲江一带,中心城区和东南山区午后易出现强度较大的短时强降水;短时强降水量和总频次呈现西部高于东部的分布特征,且与海拔高度密切相关,短时强降水量随海拔增高而显著增加。

不同场景下的融媒体直播方案研究

信息传播技术的发展和智能产品的使用,提高了媒体融合的深度。传统电视媒体可以充分利用新媒体技术条件扩大自身优势,推动融媒体语境下直播方式的多样化发展。基于此,结合当前新媒体技术、融媒体直播的发展现状,首先介绍融媒体直播的技术要素,其次,介绍融媒体背景下的主要直播设备,在此基础上,从竖屏与小屏直播、慢直播、多视角直播、多平台渠道融合直播等几个方面,阐述不同场景下的融媒体直播形式。最后,通过融媒体直播案例,介绍当前融媒体直播实践。

2021年苏州与武汉两地龙卷的环境条件与雷达特征对比分析

基于上海青浦双偏振雷达、武汉多普勒天气雷达、新一代天气雷达组网拼图、地面加密自动气象站和ERA5再分析等数据,对2021年5月14日夜间苏州、武汉相继出现的致灾严重的龙卷天气过程,从天气背景、地面触发机制、雷达探测特征和环境参数等方面进行了对比分析,结果表明:(1)苏州、武汉两地龙卷均发生在西南暖湿气流强迫背景下,低层高温高湿,均受到低空急流和超低空急流影响,但两地龙卷发生位置与对应的急流位置不同,苏州龙卷西侧对应东侧急流出口区,武汉龙卷正好对应西侧急流出口区;(2)苏州龙卷是由阵风锋引起的辐合线配合强度适宜的弱冷池触发的;武汉龙卷发生时地面存在中尺度辐合中心和弱冷池;(3)两地龙卷均发生在孤立右移超级单体伴随低层中气旋突然加强之时,龙卷涡旋特征(TVS)分别出现在苏州龙卷和武汉龙卷发生前2 min和3 min;(4)有别于美国龙卷发生的环境条件,苏州龙卷发生在高的对流有效位能、较低的抬升凝结高度和对流抑制能量以及中等偏弱的风暴相对螺旋度和垂直风切变条件下;武汉龙卷则发生在弱的对流有效位能、较低的抬升凝结高度、较高的对流抑制能量以及强的风暴相对螺旋度和垂直风切变条件下。比较而言,两地龙卷发生前和发生时,苏州龙卷的热力条件较好、动力条件中等偏弱,而武汉龙卷的动力条件较好、热力条件偏弱,可见两地龙卷均发生在热力和动力条件互补的环境下。

Contrasting Regional Responses of Indian Summer Monsoon Rainfall to Exhausted Spring and Concurrently Emerging Summer El Nino Events

The inverse relationship between the warm phase of the El Nino Southern Oscillation(ENSO)and the Indian Summer Monsoon Rainfall(ISMR)is well established.Yet,some El Nino events that occur in the early months of the year(boreal spring)transform into a neutral phase before the start of summer,whereas others begin in the boreal summer and persist in a positive phase throughout the summer monsoon season.This study investigates the distinct influences of an exhausted spring El Nino(springtime)and emerging summer El Nino(summertime)on the regional variability of ISMR.The two ENSO categories were formulated based on the time of occurrence of positive SST anomalies over the Nino-3.4 region in the Pacific.The ISMR’s dynamical and thermodynamical responses to such events were investigated using standard metrics such as the Walker and Hadley circulations,vertically integrated moisture flux convergence(VIMFC),wind shear,and upper atmospheric circulation.The monsoon circulation features are remarkably different in response to the exhausted spring El Nino and emerging summer El Nino phases,which distinctly dictate regional rainfall variability.The dynamic and thermodynamic responses reveal that exhausted spring El Nino events favor excess monsoon rainfall over eastern peninsular India and deficit rainfall over the core monsoon regions of central India.In contrast,emerging summer El Nino events negatively impact the seasonal rainfall over the country,except for a few regions along the west coast and northeast India.