“板块”模型中的共速问题探究——从2022年3月湖北省七市州联考物理卷第16题说起

2022年3月湖北省七市州联考物理卷第16题:如图1甲所示,质量mA=4 kg的物块A与质量mB=2 kg的长木板B并排放置在粗糙的水平面上,二者之间夹有少许塑胶炸药,长木板B的右端放置有可视为质点的小物块C。现引爆塑胶炸药,爆炸后物块A可在水平面上向左滑行s=1.2 m,小物块C的速度随时间变化的图像如图1乙所示。

物理问题中神奇的临界条件——共速

临界问题是诸多物理问题中很值得重视的一类。解决临界问题的关键是找出临界条件。仔细关注一下诸多的临界问题之后，会有一个很有意思的发现，就是“共速”是许多临界问题中的临界条件。

基于单片机的列车共速系统及服务杆的设计与实验研究

通过列车共速系统及服务杆的设计与实验分析,为现行列车的共速研究以及相关的服务杆设计提供研究实践基础,为后续同类型问题研究提供实践基础。

技术赋能教师专业发展:范式转换、速度隐忧及其“共速”转向

教师专业发展深受教育数字化转型影响,逐步走向“互联网+共生发展”范式。该范式内部加速逻辑与减速逻辑不断博弈,引发教师“不是发展的发展”的专业异化发展现象,并具体从空间异化、物界异化、行动异化、时间异化、自我和社会发展异化五个方面指向教师生成性教学能力、智慧教学能力、可持续发展能力、教育性教学能力和有意义教学能力等专业发展关键能力的弱化。要规避技术赋能教师专业发展的速度隐忧,需保持内生外促的“共速”发展速率,通过预成教学与生成教学、规模培育与个性发展、技术驱动与理性反思、知识传授与德化涵养、教学效率与教育情怀五个方面的共速,塑造有韧性的教师发展样态。

纤维素与草酸的慢速和快速共热解反应特性研究

本研究利用热重-傅里叶变换红外光谱和卧式固定床热解反应装置,探究了纤维素与草酸的慢速和快速共热解反应特性。慢速共热解的失重曲线包括草酸分解和纤维素分解两个阶段,由于草酸与纤维素分解不同步,草酸主要通过其分解形成的挥发分影响纤维素的分解,且影响并不明显。而在快速共热解中,草酸与纤维素同步热解,原料及挥发分之间有着充分的交互反应,因此,草酸对纤维素的三相热解产物具有显著影响。相比于纤维素单独快速热解,快速共热解形成的生物油中左旋葡聚糖、左旋葡萄糖酮含量减少,1,4∶3,6-二脱水-α-D-吡喃葡萄糖含量显著提高;热解气中CO减少,CO_(2)增多;此外,纤维素分解更为彻底,热解炭具有更高的芳香化程度。

巧用等效法快速分析滑块木板共速问题

在众多力与运动的模型当中,滑块木板是一个非常典型的模型,在历年高考试题中出镜率极高,且难度较大,近几年全国卷在压轴题中经常考查此模型。关于滑块木板模型的物理过程复杂,尤其是判断物块与木板能否以相同速度一起运动,令许多学生望而却步。通过等效法将粗糙地面转化为光滑模型,根据临界条件可迅速判断滑块木板的运动状态。

共速达:五年磨一剑——记信息化、网络化的共速达物流

十年磨一剑,可“共速达”只用了短短的五年时间,从一个业务单一的上下班接送服务公司迅速成长为集客货运、多式联运、配送及仓储于一体的专业化第三方物流企业。

整合临界条件 提升关键能力--以共速条件的应用为例

物理学习困难多数是因为学生无法进人“物理环境”,不能有效地应用物理模型解决问题。研究多个物体在同一参考系中的运动是对运动问题的更深层次学习,对学生思维能力的要求较高。该类问题多数情况都涉及某些共速条:件,抓住共速条件,围绕共速条件可使学生迅速进人“物理环境”,快速解决相关问题。共速条件在追击问题、传送带模型、板块模型、动量守恒模型、双杆模型等问题中都有重要应用,笔者对此进行以下分析。

巧用等效法快速分析滑块木板共速问题

滑块模板类问题是高中阶段物理学科中非常重要的一个知识点。同时也是考试中经常出现的热点题型。这篇文章主要介绍的就是如何利用等效分析法来解决木板滑块共速的问题。

ViewMeeting在深圳共速达公司中的应用

深圳市共速达物流股份有限公司(简称共速达)，1998年成立以来，业务不断扩大，现已拥有上千辆大巴、货运车，一个集装箱堆场和一套GPS监控调度管理系统。公司本着以特区为总控中心，拟建4个物流基地(其中一个配送中心)，辐射珠江三角洲，再次辐射全国，即以总控中心为同心圆，建立区域网络、全国性网络的战略，目前在深圳、北京、上海、南京、广州、杭州、郑州、合肥、海口等ll地建立分公司。

论《速求共眠》的电影征用与叙事探索

众所周知,文学与电影的关系并不是新鲜课题,但小说《速求共眠》在记叙如何筹拍电影以改变当代作家创作窘迫的过程中,通过对电影的重新征用,或者说以电影为方法,在当代小说文体实验与时代烛照上进行了一种新的表意探索。某种程度上,小说隐喻当代文学的表意困境与突围道路,成为反映中国人当代生活、情感、思想与某些问题的文学个案,由此在建构文学叙事的当代性上勇敢地冒险,显示出其推陈出新的独特价值。

中国版“黑色幽默”--论阎连科的《速求共眠》

阎连科的长篇小说《速求共眠》是中国版“黑色幽默”的创新之作。作者以“黑色幽默”写出改革开放以来中国普通民众的生存样相和生命体验,尤其关注处于生活底层中的人们或贫困潦倒或失魂落魄的生命脉动。小说以叙事人追求电影梦想而失败的过程为主线,巧妙穿插,摹画出新时期中国人的精神面貌。行文间不乏丰盈的想象和杂文式的批判,叙事中蕴含丰富的心理信息,对热衷于功名的文人及其合作者予以嘲讽和揶揄。借助“跨文体”的写作方式,作品也凸现了生活中荒诞的一面。

虚构与非虚构之间——论阎连科小说《速求共眠——我与生活的一段非虚构》中的含混叙事

阎连科带着对"写作"这一艺术行为与自身"小说家角色"存在意义的质疑与反思,创作了《速求共眠--我与生活的一段非虚构》,在虚构与非虚构之间演绎经济话语时代作家与文本的生成过程。叙述者的叠合模糊了虚构与非虚构边界,文类跨界指涉多重主题,文本抵牾呈现真实与虚构的对峙,最终共同构建了一个"含混艺术场",表现出作家创作的主体性理想和生活本相之间的紧张与焦虑,传达出作者含混的文化态度。以新叙事模式处理面临的新现实问题,是阎连科写作换气的一次尝试,是谢幕,也是一个全新的开始。

生物质与煤炭共热解特性及协同作用的研究（摘要）

以稻壳与褐煤为原料，采用多种方法对二者按照不同比例进行共热解时的热解特性及协同作用进行分析。主要内容和结果如下：1）利用热重分析方法对稻壳与褐煤单独热解及共热解过程进行分析。结果发现，稻壳与褐煤单独热解过程中主要热解阶段的温度范围有相互重叠部分，所以二者存在发生协同作用的可能性；稻壳与褐煤按照2：8比例进行共热解时，热失重程度有所加深，推测该条件下二者协同作用最明显。不同升温速率对热解过程有一定的影响，在较低升温速率条件下，稻壳与褐煤相互作用时间增加，协同作用相对较明显。

Effect of as-solidified microstructure on subsequent solution-treatment process for A356 Al alloy

For the compromise of mechanical properties and product cost, the end-chilled sand casting technique was applied to studying the microstructure evolution of A356 Al alloy with cooling rate and the effect of different as-cast microstructures on the subsequent solution-treatment process. The experimental results show that the secondary dendrite arm spacing (SDAS) of primaryα(Al), the size of eutectic Si and the volume fraction of Al?Si eutectic are reduced with increasing the cooling rate. Eutectic Si, subjected to solution treatment at 540 °C for 1 h followed by water quenching to room temperature, is completely spheroidized at cooling rate of 2.6 K/s; is partially spheroidized atcooling rate of 0.6 K/s; and is only edge-rounded at cooling rates of 0.22 and 0.12 K /s. Whilst the microhardness is also the maximum at cooling rate of 2.6 K/s. It consequently suggests that subjected to modification by high cooling rate, the eutectic Si is more readily modified, thus shortening the necessary solution time at given solution temperature, i.e., reducing the product cost.

Effects of cooling rate on solution heat treatment of as-cast A356 alloy

The effect of cooling rate of the solidification process on the following solution heat treatment of A356 alloy was investigated,where the cooling rates of 96 K/s and 3 K/s were obtained by the step-like metal mold.Then the eutectic silicon morphology evolution and tensile properties of the alloy samples were observed and analyzed after solution heat treatment at 540 °C for different time.The results show that the high cooling rate of the solidification process can not only reduce the solid solution heat treatment time to rapidly modify the eutectic silicon morphology,but also improve the alloy tensile properties.Specially,it is found that the disintegration,the spheroidization and coarsening of eutectic silicon of A356 alloy are completed during solution heat treatment through two stages,i.e.,at first,the disintegration and spheroidization of the eutectic silicon mainly takes place,then the eutectic silicon will coarsen.

Residual curvature migration velocity analysis for angle domain common imaging gathers

Pre-stack depth migration velocity analysis is one of the keys to influencing the imaging quality of pre-stack migration.In this paper we cover a residual curvature velocity analysis method on angle-domain common image gathers（ADCIGs） which can depict the relationship between incident angle and migration depth at imaging points and update the migration velocity.Differing from offset-domain common image gathers（ODCIGs）,ADCIGs are not disturbed by the multi-path problem which contributes to imaging artifacts,thus influencing the velocity analysis.On the basis of horizontal layers,we derive the residual depth equation and also propose a velocity analysis workflow for velocity scanning.The tests to synthetic and field data prove the velocity analysis methods adopted in this paper are robust and valid.

Pore structure and liquid flow velocity distribution in water-saturated porous media probed by MRI

Magnetic resonance imaging （MRI） was used to probe the structure and flow velocity within the interparticle space of a packed bed of agar beads under water-saturated condition. The images of the velocity field at three different flow rates were obtained. To determine the pore-parameter of the porous media, the internal structure of the bed was also obtained using image processing technique. The results show that the porosity of the sample is 31.28% and the fitting curve for the distribution of pore equivalent diameter follows Gaussian distribution. The velocity profiles do shift as the flow rate varies and the solution flow through the void space is not a homogeneous flow in any pores. The velocity distributions within the pore are roughly parabolic with the local maximum being near the center. About half of the velocity components are in the class of 0-1 cm/s. The frequency of lower velocity components is lower at higher flow rate, but to higher velocity components, it is just the opposite.

Kirchhoff PSDM angle-gather generation based on the traveltime gradient

Angle-domain common-image gathers（ADCIGs） are the basic data in migration velocity analysis（MVA） and amplitude variation with angle（AVA） analysis. We propose a common-angle gather-generating scheme using Kirchhoff PSDM based on the traveltime gradient field. The scheme includes three major operations：（1） to calculate the traveltime field of the source and the receiver based on the dynamic programming approach;（2） to obtain the refl ection angle according to the traveltime gradient field in the image space; and（3） to generate the ADCIGs during the migration process. Because of the computation approach, the method for generating ADCIGs is superior to conventional ray-based methods. We use the proposed ADCIGs generation method in 3D large-scale seismic data. The key points of the method are the following.（1） We use common-shot datasets for migration,（2） we load traveltimes based on the shot aperture, and（3） we use the MPI and Open Mp memory sharing to decrease the amount of input and output（I/O）. Numerical examples using synthetic data suggest that the ADCIGs improve the quality of the velocity and the effectiveness of the 3D angle-gather generation scheme.

Tomographic velocity inversion for ADCIGs in areas with a rugged surface

Pre-stack depth migration velocity analysis is one of the key techniques influencing image quality. As for areas with a rugged surface and complex subsurface, conventional prestack depth migration velocity analysis corrects the rugged surface to a known datum or designed surface velocity model on which to perform migration and update the velocity. We propose a rugged surface tomographic velocity inversion method based on angle-domain common image gathers by which the velocity field can be updated directly from the rugged surface without static correction for pre-stack data and improve inversion precision and efficiency. First, we introduce a method to acquire angle-domain common image gathers （ADCIGs） in rugged surface areas and then perform rugged surface tornographic velocity inversion. Tests with model and field data prove the method to be correct and effective.