Morphodynamic signatures derived from daily surface elevation dynamics can explain the morphodynamic development of tidal flats

Understanding the sensitivity of tidal flats to environmental changes is challenging.Currently,most studies rely on process-based models to systematically explain the morphodynamic evolution of tidal flats.In this study,we proposed an alternative empirical approach to explore tidal flat dynamics using statistical indices based on long-term time series of daily surface elevation development.Surface elevation dynamic(SED)indices focus on the magnitude and period of surface elevation changes,while morphodynamic signature(MDS)indices relate sediment dynamics to environmental drivers.The statistical analyses were applied to an intervention site in the Netherlands to determine the effect of recently constructed groynes on the tidal flat.Using these analyses,we were able to(1)detect a reduction in the daily SED and(2)determine that the changes in the daily SED were predominantly caused by the reduction in wave impact between the groynes rather than the reduction in tidal currents.Overall,the presented results showed that the combination of novel statistical indices provides new insights into the trajectories of tidal flats,ecosystem functioning,and sensitivity to physical drivers(wind and tides).Finally,we suggested how the SED and MDS indices may help to explore the future trajectories and climate resilience of intertidal habitats.

The impact of sea-level rise on the coast of Tianjin-Hebei,China

Bulletins of China's National Sea Level show that the average rising rate of sea-levels in China is 3.3 mm/a over the past 40 years, with an obviously accelerated rising trend in the last decade. The rate of relative sea-level rise of the Yangtze River Delta reached >10 mm/a after considering the land subsidence, and Bohai Bay is even greater than 25 mm/a. The impact of the sea level rise to the coastal area will be greater in the coming years, so carrying out an assessment of this rising trend is urgent. This paper, taking the coastal area of Tianjin and Hebei as examples, comprehensively evaluates the impact of sea-level rise through multitemporal remote sensing shoreline interpretation, ground survey verification, elevation measurements for both seawall and coastal lowlands. The results show that the average elevation of the measured coastal areas of Tianjin and Hebei is about +4 m, and the total area of >100 km^2 is already below the present mean sea level. More than 270 km, ca. 31% of the total length of the seawall, cannot withstand a 1-in-100-year storm surge. Numerical simulations of the storm flooding on the west coast of Bohai Bay, for 1-in-50-years, 1-in-100-years, 1-in-200-years and 1-in-500-years, show that if there were no coastal dykes, the maximum flooding area would exceed 3000 km^2, 4000 km^2, 5300 km^2 and 7200 km^2, respectively. The rising sea has a direct and potential impact on the coastal lowlands of Tianjin and Hebei. Based on the latest development in international sea-level rise prediction research, this paper proposes 0.5 m, 1.0 m and 1.5 m as low, middle and high sea level rise scenarios by 2100 for the study area, and combines the land subsidence and other factors to the elevation of the existing seawall. Comprehensive evaluation results indicate that even in the case of a low scenario, the existing seawall will not be able to withstand a 1-in-100-years storm surge in 2030, and the potential flooding areas predicted by the model will become a reality in the near future. Therefore, the seawall design in the coastal areas of Tianjin and Hebei must consider the combined effects of land subsidence, sea level rise and the extreme storm surges caused by it.

Numerical Simulation of Continuous Tension Leveling Process of Thin Strip Steel and Its Application

Cold-rolled thin strip steel of high flatness quality undergoes multistage deformation during tension leveling. Thus, the parameters of set-up and manipulating are more difficult. With the aid of FE code MSC. MARC, the tension leveling process of thin strip steel was numerically simulated. Concentrating on the influence of the roll intermeshes in 2# anti-cambering on the distribution and magnitude of residual stresses in leveled strip steel, several experiments were clone with the tension leveler based on the results from the simulation. It was found from the simulation that the magnitude of longitudinal residual stresses in the cross-section of the leveled strip steel regularly presents obvious interdependence with the roll intermeshes in 2# anti-cambering. In addition, there is a steady zone as the longitudinal residual stresses of the surface layers in leveled strip steel vary with the roll intermeshes of 2# anticambering, which is of importance in the manipulation of tension levelers. It was also found that the distribution of strains and stresses across the width of strip steel is uneven during leveling or after removing the tension loaded upon the strip, from which it was found that 3D simulation could not be replaced by 2D analysis because 2D analysis in this case cannot represent the physical behavior of strip steel deformation during tension leveling.

Flat Panel Solar Thermoelectric System Size Optimisation at Different Vacuum Levels

A systematic experimental investigation to understand the effect of heat loss and the thermoelectric aspect ratio (cross sectional area and length) on a flat plate solar thermoelectric system performance was carried out. The investigation involved a series of experiments on systems with 4 different sizes of thermoelectric generators, and it was tested in 5 different vacuum levels during the steady-state. The detailed experimental investigation provided a substantial amount of data, which revealed that the system performance of both heat and electricity power were improved when the heat lost was minimised. The system’s performance strongly depended on the aspect ratio of the thermoelectric generators. This finding might have a significant impact on the cost of the system by saving the user’s and the manufacturer’s time in examining different TEGs with different aspect ratios in order to get the optimum size optimisation of the hybrid system, as well as reduce the manufacturing cost.

Charged Particle in a Flat Box with Static Electromagnetic Field and Landau’s Levels

We study the quantization of a charged particle motion without spin inside a flat box under a static electromagnetic field. Contrary to Landau’s solution with constant magnetic field transverse to the box and using Fourier transformation, we found a full solution for the wave function which is different from that one given by Landau, and this fact remains when static electric field is added. However, the Landau’s levels appear in all cases.

Flat Rooftops as Productive Landscapes in Birmingham

Due to the changing global environment,sustainable development has become a goal that many cities strive towards.Producing nutritious food is a component of sustainable development.The primary purpose of this paper is to assess Birmingham’s suitability for flat rooftop farming.This study explores two examples of rooftop farms:Brooklyn Grange in New York and Thammasat University,the largest rooftop farm in Asia,and they transformed the roof into a productive rooftop farm.This paper proses the tops of the buildings at Birmingham City University to be converted into a flat roof farm with an additional survey into the dietary habits of Birmingham inhabitants.With a productive landscape,one can achieve societal ideals such as urban or communal food self-sufficiency,reduce food imports,transit expenses,and consumer prices,encourage human interaction and connection,and at the same time provide diversified and healthy food.

Region Division and Stress Analysis for Plate Roller Leveling Process

The flatness of leveled plate is settled by residual stress. According to stress distribution simulated by FEM software ANSYS/LS-DYNA, the plate can be divided into non-steady region and steady region. The nonsteady region is composed of four zones, two of which are about half of leveling roller pitch at leading and end edges and other two are about 10% of the width at lateral edges. The steady region is the rest part enclosed by the non-steady regions. It is helpful to improve the leveling process by analyzing forming mechanism of each region and selecting suitable processes settings.

Research on confirmation of basic technological parameters of tension levellers based on neural network and genetic algorithm

Confirmation of basic technological parameters of tension levellers is the most important factor of leveling strip. Up to now, most factories have used experts’ experience to decide these parameters, without any established rule to follow. For better quality of strip, a valid method is needed to decide technological parameters precisely and reasonably. In this paper, a method is used based on neural network and genetic algorithm. Neural network has a good ability to extract rules from work process of tension levellers. Then using neural network, which has learned from a lot of working samples, to be the evaluation of fitness, genetic algorithm could easily find the best or better technological parameters. At the end of this paper, examinations are given to show the effect of this method.

杭州湾北岸现代潮滩沉积物粒度特征及其对古海平面的指示意义

对杭州湾北岸3处现代潮滩沉积物进行高精度粒度分析,查找研究区潮滩不同微相的粒度特征和差异,提取基于粒度分析的潮滩微相识别敏感指标,并将其应用到该区域的全新世钻孔潮滩沉积物中,识别钻孔潮滩沉积微相,据此建立研究区全新世早期的海平面曲线。研究表明:杭州湾北岸现代高潮滩盐沼沉积物粘土含量明显高于高潮滩下部和中潮滩,而砂含量与之相反;高潮滩盐沼平均粒径等粒度参数明显小于中、高潮滩的粒度参数;盐沼沉积物粒度频率曲线峰态宽缓,明显区别于高潮滩下部和中潮滩。上述现代潮滩微相粒度敏感指标可成功应用到钻孔潮滩沉积微相划分中,并建立了该区域全新世早期海平面曲线。曲线显示,9700~8700 cal a BP期间海平面上升约11.6 m,海平面上升速率可达1.2 cm/a。现代潮滩不同位置沉积物粒度参数的规律性差异可作为潮滩微相识别的有效指标,为古潮滩沉积微相识别和古海平面重建提供参考依据。

高频电磁镜面板平面度测量的不确定度评定

针对某部队高频电磁镜面TEM室的镜面板平面度误差测量与评定任务,从测量仪器的选择、测量误差的评定等方面解决镜面板平面度测量不确定度的评定问题。与传统的平面度误差测量不确定度评定方案不同,重点针对高频电磁镜面TEM室的超大镜面板平面度进行不确定度评定。测量方法采用相对测量法,从测量便利性方面选择合像水平仪,误差评定选择最小二乘法,基于MATLAB融入蒙特卡罗方法对其进行平面度误差评定,评定结果为4μm,解决了高频电磁镜面板的平面度误差评定问题,保证了高频电磁信号的高保真传递,实现了大型TEM喇叭、D-dot等电磁传感器的精确校准。

关于消防救援指挥体系建设的思考

改革转隶后,国家综合性消防救援队伍的职能定位从传统的消防监督、火灾扑救为主向应对“全灾种、大应急”拓展。为进一步适应新形势下应急救援任务需要,提升消防救援队伍作战能力素养,健全队伍“灭大火、打大仗”的能力,本文以消防救援指挥体系为研究对象,对当前消防救援指挥体系现状及问题进行分析研究,提出了牢固树立“全灾种、大应急”意识、强化信息化手段应用、多途径缓解执勤压力、推动灭火救援岗位职业资格认定、科学制定力量编成、探索推行专业指挥模式6项对策,为消防救援队伍指挥体系建设提供一定的理论支撑。

基于置信水平的钢轨焊接接头设备状态评定方法

[目的]为解决我国无缝线路钢轨设备状态评定体系不完善的问题,需要建立基于置信水平的钢轨焊接接头设备状态评定方法。[方法]阐述了目前我国规定的高速铁路钢轨平直度允许偏差、焊接接头平直度允许偏差。以我国某条已开通运营13年的高速铁路为案例,对该线钢轨焊接接头平直度数据进行分析,认为钢轨接头平直度检测数据总体服从正态分布。根据正态分布及置信区间原理,对均值和标准差评定法、置信水平评定法进行对比,提出了基于置信水平的钢轨焊接接头设备状态评定方法,得到高速铁路钢轨设备状态的评定标准。[结果及结论]该方法能够客观、直观地反映出钢轨焊接接头的设备状态,可以准确地掌握钢轨设备状态。该方法可为分析钢轨设备变化规律,以及制定大中修的标准、计划及方案等提供很好的理论依据。

蒙皮结构侧墙校平工艺方法的研究与应用

文章针对货车薄板侧墙焊接后平面度超差的问题,分析了几种常规校平方法的适应性,最终提出了电磁点状校平工艺方法,并通过工艺对比试验和样车试制生产验证,证明了该校平工艺方法的可行性,解决了货车制造领域薄板校平方面的技术难题。

隧道平整度控制光面爆破及“刮刀+三刮两平”工艺优化施工技术研究

在隧道施工的过程中,隧道初支平整度是隧道施工质量控制的关键,隧道初支平整度与隧道二次衬砌的质量密切相关,例如二次衬砌厚度不足、背后脱空等严重的质量缺陷,为确保隧道初支平整度,隧道施工过程中采用聚能光爆和“三喷两刮一扫面”工艺进行施作,初支平整度效果良好。

大型地下车库混凝土地面整平施工方法研究与探讨

本文论述的施工工法主要是利用激光整平机的自动找平功能和小型机具设备的施工灵活性,结合混凝土中布置抗开裂钢筋网片,以及混凝土浇筑成型后采用磨光机打磨、压光等多道工艺方法。在房屋和市政工程大型地下车库及地下停车场大面积混凝土地面整平及施工过程中,能加快进度、降低成本、减少混凝土开裂等质量缺陷,同时也提高了混凝土地面施工工艺水平。

伏龙大桥工程路线与阻水率设计总结

伏龙大桥受地理位置限制,有许多控制设计的关键因素需从方案阶段就开始充分考虑。为使防洪评价报告能顺利通过相关审批,在桥梁路线优化设计时,就要充分考虑关键因素阻水率的影响,规划路线经过局部优化,以避免大斜交。从方案设计到施工图阶段,阻水率这一指标在路线优化和总体方案确定的过程中,起到了决定性作用。防洪评价过程中的阻水率对设计路线和方案近乎有“一票否决权”。故从方案阶段开始关注阻水率,避免了方案返工。优化阻水率可从跨径、桥墩尺寸、与水流夹角等方面进行。

Wind tunnel simulation of pollutant dispersion inside street canyons with galleries and multi-level flat roofs

In this study, the pollutant dispersion within street canyons is studied by experiments conducted in an environmental wind tunnel. The vehicular exhaust emissions are modeled using a line source. The pollutant （smoke） concentrations inside the canyons are measured based on a light scattering technique. The pollutant concentrations within the four different street canyons containing the galleries and the three-level flat-roofs under both the isolated and urban environments are obtained and discussed. For each of the four canyon configurations investigated, it is found that there is an obvious discrepancy between the pollutant dispersion patterns under the isolated environment and the urban environment. The three-level fiat roof is found to significantly influence the pollutant distribution pattern in a street canyon. In order to clarify the impacts of the wedge-shaped roofs on the pollutant dispersion inside an urban street canyon of an aspect ratio of 1.0, the pollutant distributions inside urban street canyons of three different wedge-shaped roof combinations are measured and analyzed. It is revealed that the pollutant distribution pattern inside the urban street canyon of an aspect ratio of 1.0 is influenced greatly by the wedge-shaped roof, especially, when an upward wedge-shaped roof is placed on the upstream building of the canyon. Images from this study may be utilized for a rough evaluation of the computational fluid dynamics （CFD） models and for helping architects and urban planners to select the canyon configurations with a minimum negative impact on the local air quality.

北石窟寺平顶窟顶板稳定性评价与黏结补强有效性研究

顶板岩体层间开裂、崩落是砂岩石窟平顶窟顶板结构失稳的主要病害之一。调查北石窟寺平顶窟顶板发现,地层岩性、岩体层间抗拉强度、剥离体厚度、开口宽度及剥离体与基岩体连通率是影响开裂体稳定性的主要因素。为有效提高平顶板安全储备,增强平顶窟顶板的整体稳定性,根据现场调查和定量计算分析,将顶板开裂岩体划分为低风险、中风险、高风险、极高风险4个等级,抽象简化为“悬臂式折断破坏”和“重力式坠落破坏”两种主要破坏方式,并提出针对北石窟寺顶板开裂岩体稳定性评价的定量计算公式。通过北石窟寺现场注浆黏结试验发现,填充浆液面积覆盖率一般为40%~60%,对剥离体厚度不大于11.4 cm的裂隙岩石进行黏结加固可取得较为理想的效果,考虑8度抗震设防,其有效黏结厚度不大于10.89 cm。

一种平板检定装置测量结果不确定度评定方法

检定装置的测量不确定度是确保量值传递准确性的重要指标参数,所以测量不确定度评定方法及过程尤为重要。本文介绍一种以电子水平仪为主标准器的平板检定装置的测量不确定度评定方法。依据JJG117-2013《平板检定规程》规定的检定方法,从工作原理进行分析,构建数学模型,分析不确定度来源,进行了标准不确定度分量分析,阐述了计量标准测量不确定度的评定方法。

玉米秸秆翻埋联合整地机整平装置的设计与试验

平整的种床利于机械播种,又能节水保墒,是保证小麦播种质量的重要条件。为此,根据小麦播种对整地质量的要求,进行了整平部件的设计与分析。旋耕整平装置主要由旋耕机、镇压辊等构成,以旋耕整平装置中关键部件旋耕刀作为模型,采用EDEM离散元仿真方法,研究旋耕刀转速、旋耕整平装置前进速度及刮平板角度对地表平整度的影响。仿真结果表明:旋耕刀转速为310.84r/min、前进速度为1.52m/s、刮平板角度为170°时,地表平整效果最好,平整度为0.3mm。对整平装置进行田间试验,结果表明:地表平整度平均值1.81cm,满足小麦播种前的平整度要求。