Climate Changes and Sustainability

Climate change is the phrase used to describe long-term changes in temperatures and weather patterns. Changes in the atmosphere and their interactions with diverse geologic, chemical, biological, and geographic variables are the main contributors to this cyclical adjustment of the Earth’s climate. Such changes may be induced purposefully, because of burning fossil fuels, clearing forests, and raising animals, or they may be natural, brought on by significant volcanic eruptions or variations in the sun’s activity. By significantly increasing the amount of greenhouse gases already in the atmosphere, this heightens the greenhouse effect and contributes to global warming. This work includes several additional theoretical and practical explanations of sustainable development. The theoretical work encompasses hundreds of researches that identify requirements for how development routes might satisfy sustainable development (SD) criteria using economic theory, complex systems approach, ecological science, and other techniques. The agreements made by the Parties in various nations across the world will consider a wide range of perspectives about what would be considered undesirable effects on the environment, the climate system, sustainability, economic growth, or food production.

Eternal Climate Change Patterns and the Causes and Countermeasures of Global Climate Change

It is an objective fact that the weather is unpredictable.Even the famous meteorologist,Academician Chu Ko Chen,has only a partial understanding of the changing laws of wind and rain.Even though ancient people summarized the 24 solar terms by observing the annual activities of the sun for a long time,because they ignored the impact of the activities of the moon on the Earth’s climate change on a small scale,the 24 solar terms they summarized often could not accurately predict the change of the Earth’s climate.Therefore,the author studied the influence of lunar activities on the Earth’s climate change,finds out the law of the influence of lunar activities on the Earth’s climate change on a small scale,and summarizes the eternal climate change pattern determined by the activities of the sun and the moon.In addition,the author also reveals the causes and countermeasures of global warming and the frequent occurrence of extreme weather as well as environmental change.

Study of electromagnetic characteristics of stress distribution and sudden changes in the mining of gob-surrounded coal face

The incidence of dynamic coal or rock disasters is closely related to the distribution of stress in the surrounding rock. Our experiments show that electromagnetic radiation （EMR） signals are related to the state of stress of a coal body. The higher the stress, the more intense the deformation and fractures of a coal body and the stronger the EMR signals. EMR signals reflect the degrees of concentrated stress of a coal body and danger of a rock burst. We selected EMR intensity as the test index of the No.237 gob-surrounded coal face in the Nanshan coal mine. We tested the EMR characteristics of the stress distribution on the strike, on the incline and in the interior of the coal body. The EMR rule of rock bursts, caused by sudden changes in stress, is analyzed. Our research shows that EMR technology can be not only used to test qualitatively the stress distribution of the surrounding rock, but also to predict a possible occurrence of rock burst. Based on this, effective distress measures are used to eliminate or at least weaken the incidence of rock bursts. We hooe that safetv in coalmines will be enhanced.

Research on the sudden changes and the controlling factors of deep coal mining conditions

It was illustrated that the mining conditions inducing disasters changed with depth both in regularity of gradual and sudden change.The sudden change depth for different disaster conditions are different and controlled by different factors.The high temperature and its change with depth are mainly controlled by strata structures and rock heat conductiv- ity property,the high rock stress and dynamical engineering disasters and their change with depth are mainly controlled by tectonic conditions,roof strata rock property and deep rock mechanical property,coal mine water disasters and their change with depth are mainly con- trolled by rock mechanical property of coal seam floor and regional groundwater circulation conditions,gas disaster conditions and their change with depth are mainly controlled by buried conditions of coal seam and opening conditions of geological structures.It is men- tioned that the key point for the control of deep coal mining disaster is to clearly understand the sudden change depth of different factors causing disasters.

Effects of sudden change in wind loads on running performance of trains on a highway-railway one-story bridge in crosswinds

To investigate the effects of sudden change in wind loads on the running performance of trains on the bridge in crosswinds,a highway-railway one-story bridge was taken as the research object.Aerodynamic coefficients of the train and the bridge were measured in a series of train-bridge system segment models through wind tunnel tests when two trains passed each other on the bridge and when a train entered and left the wind barrier section of the bridge.Based on the improved SIMPACK and ANSYS rigid-flexible coupling simulation method,a wind-double train-track-bridge system coupled vibration model was established.The dynamic responses of the train were analyzed under the effects of sudden change in wind loads caused by two trains passing each other and a train entering and leaving the wind barrier section of the bridge.The results show that the effects of sudden wind load change caused by the trains passing each other had less effects on the running safety of the leeward-side train than the wind shielding effect caused by the windward-side train in the wind speed range of 10−25 m/s.With the decrease in the porosity of wind barriers,the effects of the sudden wind load change played an increasingly important role in the running safety and comfort of the train.With the increase in wind speed,the lateral response of the train increased obviously because of the effects of sudden wind load change,which affects both the lateral running stability and the comfort of the train.

佳木斯市2011年-2020年地表水生态环境质量变化研究

采用Spearman秩相关系数法,对松花江佳木斯市2011年-2020年期间主要污染指标变化趋势进行了分析。计算结果表明,2011年-2020年佳木斯上断面的高锰酸盐指数、化学需氧量、氨氮和总磷,佳木斯下断面的化学需氧量和总磷,江南屯断面的化学需氧量,同江断面的高锰酸盐指数、化学需氧量和总磷,汤旺河口内断面的化学需氧量、氨氮和总磷,梧桐河口内断面的化学需氧量和总磷呈显著下降趋势;其余监测断面的这几项监测指标无显著变化。对污染物的年际变化进行了分析,并探讨了地表水环境质量变化原因。

中国城市洪涝问题:现状、成因与挑战

全球气候变化和快速城市化双重影响下,中国城市洪涝问题日益严重,已成为影响中国城市公共安全与区域高质量发展的突出瓶颈。本文基于文献资料、灾情数据、统计年鉴等,梳理了中国城市洪涝类型与灾害特点,总结了城市洪涝的基本现状与发展趋势,阐释了城市洪涝形成机制与灾害成因,分析了城市降水变化、产汇流特性变化、排水格局变化及规划与管理对城市洪涝的影响;为科学认识中国城市洪涝问题和实现变化环境下城市洪涝科学治理,从基础数据监测与信息共享、基础理论与机理研究、成因驱动与量化识别、城市洪涝预警预报与风险评估技术以及城市洪涝灾害管理等6个方面,指出了当前研究面临的主要挑战与未来研究的重点方向。

论族群文化变迁的形式和原因

文化变迁是指文化出现的各种变化。据此,研究文化变迁的重点,就是对文化变迁的形式和原因做出说明。对整体性文化变迁的研究,最适合从族群文化的层面展开。族群文化变迁有量变和质变这两种基本形式。前者是指族群文化所包含的具象文化的种类数量的增加和减少。一般来说,增加意味着族群文化的进化,减少意味着族群文化的退化。后者是指族群文化所包含的具象文化从一种性状变为另一种性状。一般来说,变得好用意味着族群文化的进化,变得不好用意味着族群文化的退化。族群文化之所以发生变迁,以往学界有进化论、传播论和功能论的解释,但全都具有片面性。实际上,族群文化发生变迁,应该是由两个层面的原因共同导致的。创造、传播、变革、建设和强制是族群文化发生变迁的表层原因,人的需求及其变化则是深层原因。

机床加工的精密气动卡盘研发

数控机床精加工工序中,自动卡盘夹紧力突变可引起机床精加工的形状误差、位置误差和环形工件的圆度误差。通过对数控机床加工的精密气动卡盘的研发与设计,可有效解决气动卡盘夹紧力突变的问题,推动我国数控机床的科技进步,为同类其他产品的设计提供分析基础和理论参考。

广东清远客家话的接触性音变

田野调查所得语料显示,清远客家话有些字的声、韵、调,与一般客家话区别明显,主要有:少数古全浊声母字清化后读塞音塞擦音时不送气,少数见母字读k h-声母等;荔今读洪音,网今读无-i-介音,有多个撮口呼韵母;阴平是个高平调55,归阴平的浊上字偏少。参考清远粤方言等相关研究成果,梳理出引起清远客家话这些音变的线索,为接触性音变研究提供语言事实。

1991—2021年我国孕产妇死亡率变化情况分析

目的:分析1991—2021年我国孕产妇死亡率及其变化趋势,为制定妇幼健康有关的政策提供科学依据。方法:通过《中国卫生统计年鉴》收集1991—2021年我国孕产妇死亡数据,运用JoinPoint模型,采用平均年度变化百分比(AAPC)和年度变化百分比(APC)分析孕产妇死亡率变化趋势。结果:1991—2021年我国孕产妇死亡率整体呈下降趋势,AAPC为-5.00%,其中1991—2005年APC为-3.71%,2005—2013年APC为-8.16%,2013—2021年APC为-4.05%。1991—2021年我国城市孕产妇死亡率整体呈下降趋势,AAPC为-3.90%,30年间变化趋势出现2个拐点,其中1991—2002年APC为-5.17%,2002—2010年APC为0.70%,2010—2021年APC为-5.82%;1991—2021年我国农村孕产妇死亡率整体呈下降趋势,AAPC为-5.60%,30年间变化趋势出现2个拐点,其中1991—2004年APC为-3.55%,2004—2011年APC为-11.26%,2011—2021年APC为-4.14%。孕产妇主要死亡疾病为产科出血、妊娠期高血压疾病、心脏病、羊水栓塞、产褥感染和肝病。结论:1991—2021年我国孕产妇死亡率整体呈下降趋势,2005—2013年下降幅度较大,农村孕产妇死亡率下降幅度大于城市。产科出血、妊娠期高血压疾病、心脏病、羊水栓塞仍是产科主要死亡疾病,应进一步加强政策支持并优化多学科、全孕期精细管理,以保障孕产妇安全。

原因欠缺导致赠与财产返还的原理和规则

赠与合同的原因体现为赠与人负担债务的“决定性动机”,这种“决定性动机”欠缺时,应当否定赠与合同的拘束力。因此,若赠与合同的原因欠缺,即使在赠与人移转赠与财产权利后,仍有否定赠与合同拘束力,认可赠与财产返还的需要。关于否定赠与合同拘束力的具体路径,“附解除条件的赠与”构成建立在对当事人意思的拟制之上,有不当干涉当事人意思自治之嫌,应当区分赠与合同原因欠缺的发生时点,分别采用错误构成和情事变更构成。若原因欠缺自始发生,则原因欠缺可能构成错误,即使该项错误属于狭义的动机错误,也应当允许赠与人主张错误撤销。若原因欠缺嗣后发生,则原因欠缺可能构成赠与合同基础情事的变更,赠与人可依情事变更规则解除赠与合同。原因欠缺导致赠与财产返还的原理亦可用于对彩礼返还规则的解释和对父母出资为已婚子女购置房屋后子女离婚所引发的财产返还问题的解决。

基于磁流体轴承的大载荷磁流体二维导轨平台研究

在现有的精密机床中,空气静压导轨平台存在阻尼突变、载荷不高的问题,基于磁流体轴承,提出了一种大载荷磁流体二维导轨平台。首先,对基于磁流体的导轨平台关键问题进行了研究,包括空气损耗问题和磁流体尾迹问题;然后,采用磁流体压力轴承设计了一个双U形导轨平台结构,并将顶部、底部和侧部轴承垫紧密地放置在一起,从而在动子上形成了一个储液层;采用上下磁化配置的导轨平台具有6个轴承垫,每个轴承垫由多个小型磁体组成;其次,对载荷能力、刚度和涡流阻尼进行了数值模拟;最后,选用了煤油基磁液、铝材和铁素体不锈钢制备了一台平台样机,进行了平台的性能测试,对该导轨平台的有效性进行了验证。研究结果表明:该平台的平面度为±7μm,具有较高的可重复性,明显优于现有基于磁流体轴承的精密运动系统;在相同行程和尺寸条件下,与气动平台相比,该平台的最大有效载荷为140 N,提高了40%;阻尼在2 N·s/m至4 N·s/m之间相对恒定,且可预测,解决了气动平台的阻尼突变问题,有利于实现导轨平台高精度定位的目的。

季风涡旋对台风“烟花”路径突变的影响

台风“烟花”于2021年7月22日00时(世界时,下同)在台湾岛东侧突然向北转向,但美国、日本和中国的业务预报均没有正确预报出该过程。基于NCEP/NCAR提供的全球再分析资料(Final Operational Global Analysis,FNL),采用Lanczos滤波方法分析发现,台风“烟花”转向前的西行减速主要受到与季风涡旋有关的季节内尺度环境引导气流分量的影响,向北转向及转向后的向北加速则主要受到季风涡旋和台风相互作用导致的天气尺度环境引导气流分量的引导,主要和beta涡旋对旋转、与季风涡旋的合并、以及加强的Rossby波能量频散这3个重要过程有关。台风“烟花”在纬向尺度约3 000 km的季节内尺度季风涡旋北部的偏东气流西移过程中,与季风涡旋相互作用导致beta涡旋对气旋性旋转,通风流经历东南风—东北风—西南风的转变,使得“烟花”向西减速并逐渐向季风涡旋中心移动,并于7月22日00时与季风涡旋合并,加强了Rossby波能量频散,使得“烟花”东南边缘的天气尺度西南风加强,为缓慢移动的“烟花”提供了向北的引导,“烟花”突然向北转向。

基于正序突变量相轨迹辨识的可再生能源配电网电流保护

【目的】随着可再生能源的大量接入,中性点经小电阻接地的配电网潮流不确定性使得传统三段式电流保护的整定变得日趋复杂,其灵敏性和可靠性都有所降低。为了解决上述问题,提出了一种基于正序突变量电流相轨迹辨识的新型电流保护方法予以应对。【方法】首先,分析了故障点上游、下游的正序突变量电流大小及其分布特征;其次,利用亲和力聚类算法,根据聚类结果识别定义的主故障路径;最后,提出一种搜索方法,将搜索得到的正序突变量产生源头,即位于主故障路径上的最后一级馈线视为故障馈线。【结果】基于PSCAD的仿真研究表明,所提出的保护方法能够适应各种故障工况,不受分布式电源加入的影响,具有较高的灵敏度和可靠性。【结论】研究结果有助于提升中性点经小电阻接地的配电网运行安全性,同时提升故障排查效率。

全移相双有源全桥直流变换器的瞬态电流偏置抑制策略

针对双有源全桥(DAB)直流变换器在功率突变时产生的电流偏置问题,该文提出一种新的瞬态直流偏置抑制策略。首先,以基于全移相调制的双有源全桥直流变换器为研究对象,分析DAB变换器产生直流偏置的原因及危害。然后,在全局电感电流应力最优结果的基础上,对功率在四个工作区域突变时产生的瞬态直流偏置问题进行详细分析,推导各种电流突变情况下的直流偏置表达式,并据此提出一种新的过渡态引入方法,对于不同的功率突变状态可以得到统一的过渡移相角表达式,简化了控制过程。接着,根据所得过渡态结果,提出统一的载波调制方法,并对调制策略的适用性进行分析。最后,通过实验平台验证了所提方法可以有效消除功率突变时产生的电流偏置。

天津市中心城区典型河道水质变化规律及污染成因分析

为实现天津市中心城区河道水环境的长效改善,以调水循环线路上的卫津河段流域为典型河道,选取八里台和纪庄子桥两个监测断面,分析NH_(3)-N、COD_(Mn)、COD_(Cr)质量浓度在年内的变化规律可知,非汛期三项指标质量浓度较低,汛期质量浓度均显著升高,严重超出地表水Ⅴ类标准。汛期泵站排水是引起河道污染物质量浓度增加的重要原因,利用系统聚类法识别引起河道断面污染物质量浓度升高的主要泵站。结果表明:八里台断面的污染物主要来源于双峰道泵站,其次为海光寺泵站;纪庄子桥断面的污染物主要来源于梅江泵站、体院北泵站和浯水道泵站。因此,在汛期应持续监测主要污染泵站的排水水质,并根据污染物质量浓度,调整泵站排水量。上述几个主要污染泵站的收水区未完全实现雨污分流,造成生活污水直接排放至河道,故落实泵站收水区域的雨污分流是改善卫津河水质的长效机制。

不同含水率对磷块岩热红外辐射特征的影响研究

为探究不同含水率磷块岩的热红外辐射特征,分别对烘干磷块岩、天然含水磷块岩和饱水磷块岩进行单轴加载试验,分析不同含水率磷块岩的受力特性、破坏特征和红外辐射特征。结果表明:磷块岩含水率越高,在失稳前红外辐射的升温幅度越大,含水率越低,升温幅度越小;磷块岩红外前兆异常显示,临近破裂前会出现短暂降温现象,含水率越高,降温幅度越小,含水率越低,降温幅度越大;磷块岩在最终破裂瞬间会发生红外辐射温度突升,含水率越低,突变值越大,含水率越高,突变值越小。

厚度突变煤层采动围岩应力显现及岩移规律研究

为研究煤岩层厚度突变条件下采动围岩应力显现及岩层移动规律,采用FLAC3D数值模拟软件对平煤十矿己15.16-24110工作面煤厚和倾角突变影响区域进行建模,模拟赋存条件突变煤体在采动影响下围岩位移和应力显现规律,进而分析顶底板失稳产生的原因及规律。结果表明,随着开采深入,卸压区和应力集中范围变大;在煤层突变的位置,煤层工作面煤壁及围岩出现卸压区影响范围突然扩大,顶板卸压范围变大,形成“双驼峰”状,煤壁的应力集中系数增加明显;煤厚突变区域上覆及下伏岩层应力显现和岩移量均明显高于其他区域,说明该区域易蓄积能量,成为动力灾害及岩层失稳频发区域。