A new approach to pedestal differentiation for soil loss estimation-a case study from a burnt area in north-central Portugal

Soil pedestals have long been used as qualitative indicators of soil splash erosion.In rangelands,plant-capped pedestals,generally grass tussocks,have also been used to quantitatively estimate soil loss since the first half of the twentieth century.In agricultural lands,forests,and bad-lands,stone-capped pedestals have been used as qualitative and semi-quantitative indicators of active,'extreme'erosion.Little work has been reported on using capstone pedestal data for quantifying soil loss.We postulate that three distinct capstone pedestal types may be present in any given location and that a detailed analysis of a pedestal height histogram may be used to recognize their populations.This analysis can subsequently inform if soil loss can be reliably estimated and if so,which of the existing methods using pedestal height data will provide more accurate results.The three proposed capstone pedestal types are:(1)neo-pedestals formed underneath surface stones exposed by(partial)removal of the soil surface cover;(2)endo-pedestals formed underneath stones that were buried in the soil but have been exposed by erosion;and(3)phoenix-pedestals formed underneath stones from collapsed pedestals.In the pedestal height histogram of any given location,a skew to smaller heights may indicate the existence of endo-and/or phoenix-pedestals,which may be revealed as a bi-(or tri)modal distribution when using a smaller bin size.This concept was applied to a case study where soil loss had been monitored for control plots and mulched plots during a 5-year period following wildfire in a eucalypt plantation.We measured pedestal heights and used methods to quantitatively assess soil loss from soil pedestal data in the available literature.Soil pedestal data at the end of the 5-year period under or overestimated soil loss in the control treatment,with results ranging from 60 to 115%of measured soil loss,depending on the method.It is postulated that phoenix-and endo-pedestals may be a driving factor behind the observed discrepancies.We discuss how future research may provide more insight into dominant processes,and how frequency distributions may be used to select the best methods for estimating soil loss from pedestals.

Is the Cape Stone Forest in Shantou City formed by wave erosion? A comparison of the pedestal rocks on the coasts and the mountains of Queshi in eastern Guangdong, China

Cape Stone Forest is a group of granite rock pillars(pedestal rocks) towering over Shilin Lake, on the southern shore of Shantou Bay in eastern Guangdong, China. The rock pillars were previously identified as sea stacks because they have marine notch-like concave sidewalls at their base, and more importantly, the lake is immediately adjacent to the bay, which is exposed to the open sea. However, rock pillars similar in shape and size can also be found at the top of Queshi Mountain, which is only about 300 meters northwest of the lake and about 85 meters above sea level. Therefore, the marine origin of Cape Stone Forest is seriously questioned. In this study, 3D imagery and drone technology were used to collect data in the investigations without direct manual measurements in the water or on the mountain. It shows that the concave sidewalls of the rock pillars in the lake and on the mountains occur at different heights and are exposed to different directions, while a natural sea stack on Mayu Island at the mouth of Shantou Bay has a horizontal notch parallel to the sea level, although the granite rock of the sea stack is the same as that of the lake and the mountains. The eastern side of the island, where the sea stack is located, is exposed to the open sea but blocks large waves for the rock pillars in the lake. Therefore, the origin of Cape Stone Forest cannot be explained by wave-based mechanisms. The only satisfactory explanation that takes into account all the field evidence is that the narrow rock pillars of the lake and mountain were formed by chemical weathering that penetrated closely the spaced joints of the granite rock, and the notch-like concave sidewalls were formed by more effective chemical weathering at the base of the pillars.

Observation of Pedestal Plasma Turbulence on EAST Tokamak

Pedestal plasma turbulence was experimentally studied by microwave reflectometry on EAST tokamak. The characteristics of edge pedestal turbulence during dithering L-H transition, ELM-free H-mode phase and inter-ELM phase have recently been studied on EAST. An edge spatial structure of density fluctuation and its dithering temporal evolution is observed for the first time on the EAST tokamak during the L-H transition phase. A coherent mode usually appears during the ELM-free phase prior to the first ELM on EAST tokamak. The mode frequency gradually decreases as the pedestal evolves. Analysis shows that the coherent mode is in the pedestal region inside the separatrix. In plasma with type-III ELMs, a precursor mode before ELM is usually observed. The frequency of the precursor was initially about 150 kHz and gradually decreased till the next ELM. The mode amplitude increases or shows saturation before ELM. In the plasma with compound ELMs composed of high and low frequency ELMs, the precursor was also observed before the high frequency ELM while the harmonic oscillations with frequencies of 20 kHz, 40 kHz and 60 kHz appear before the low frequency ELM.

The Research of EAST Pedestal Structure and Preliminary Application

The pedestal characteristic is an important basis for high confinement mode （H- mode） research. Because of the finite spatial resolution of Thomson scattering （TS） diagnostic on Experimental Advanced Superconducting Tokamak （EAST）, it is necessary to characterize the pedestal with a suitable functional form. Based on simulated and experimental data of EAST, it is shown that the two-line method with a bilinear fitting has better reproducibility of pedestal parameters than hyperbolic tangent （tanh） and modified hyperbolic tangent （mtanh） methods. This method has been applied to EAST type I edge localized mode （ELM） discharges, and the electron pedestal density is found to be proportional to the line-averaged density and the edge pressure gradient is found to be proportional to the pedestal pressure. Furthermore, the ion poloidal gyro-radius has been identified as the suitable parameter to describe the pedestal pressure width.

Decorative Arts of the Qing-Style Pedestal of Outdoor Furnishings

The pedestal of outdoor furnishings is a facility of courtyard outdoor furnishings. It is an important part of ceremonial furnishings in official buildings. The Qing-style pedestal of outdoor furnishings has unique shapes and ornamentations as well as rich artistic connotation. In addition to having significant artistic value and historical value, it also embodies the user’s aesthetic taste.

LOW SIDELOBE APERTURE DISTRIBUTION OF MULTI-STEP AMPLITUDE QUANTIZATION WITH PEDESTAL

A low sidelobe aperture design method of multi-step amplitude quantization with pedestal is proposed, and general analysis and formulas are described. The computation results compared with our previous method "Multi-Step Amplitude Quantization(MSAQ)" on peak side-lobe level, aperture efficiency, normalized input power and sidelobe degradation with tolerance are given. It is shown that, under the same conditions, the method presented in this paper is better than the MSAQ.

Transient Response of the Starting Rotor System with the Fault of Pedestal Looseness

The dynamic model of a pedestal looseness rotor system is built and the dynamics of the system near the resonance region is analyzed using the KBM method. Then the asymptotic method to study a dynamic system with slow-changing parameters is used to study the starting and braking course of the system. Finally, the analytical results are proved by experiment. The results can be used in the inspecting and fault diagnosis of a rotor system of this type.

Predictive Index to Quality of ESLs’Short-Length Speech

For accurately predictingthe quality of ESLs’(English as a second language learner)short-length speech,a three-dimen⁃sional system Discourse Richness(DR)is proposed based on the previous studies,it consists of lexical richness(LC),syntactic rich⁃ness(SR)and readability(R).A computational system is used to automate the measurement of DR.The results show that no strong interactionexists among three dimensions of DR.10 indices,namely MLC,LS1,LV,VS1,VS2,CVS1,MSTTR,LogTTR,CVV1 and S can be used to predict the quality of ESLs’short-length speech.The result enables ESL teachers and researchers to judge the quality of ESLs’speech through DR and provides insights into how DR may effectively predict the quality of ESL learners’shortlength speech.

大型精密测量相控阵雷达天线座力学仿真应用研究

超大规模雷达天线座结构系统复杂,造价高、研制周期紧张,如何保证天线座结构设计一次成功,满足雷达结构技术要求是天线座研制的难题。文中结合工程研制,从天线座结构系统力学设计,计算模型建模原则、建模方法、轴承等关键部位连接处理、仿真模型简化与等效,有无斜梁结构方案仿真结果比较与选取,以及轨道平面度、辅助支撑力确定到最终结构优化进行了阐述,对大型雷达天线座结构设计具有一定的指导意义。

某型雷达天线座旋变轴弯曲故障分析

研究对象为机械扫描的多普勒体制机载雷达,采用平板裂缝天线和伺服传动系统实现雷达的波束扫描。天线座是伺服传动系统的关键组成部分。该型天线座已稳定生产多批次,工艺变更后进行了试生产,首件在随机振动验证试验中出现了方位旋变轴弯曲故障。在分析天线座组成和工作原理的基础上,通过开展仿真分析和试验验证,给出了故障产生的原因和机理,并采取了针对性的改进措施,有效地确保了后续批产天线座的质量稳定,对同类工程问题具有重要的参考价值。

先张法折线预应力施工优化方案研究

目前我国既有先张台座绝大部分用于生产中小跨径的直线预应力预制梁,其设计特点一般是能承受较大顺预应力方向剪力,但无法抵抗很大倾覆力矩。当生产较高折线预应力梁时,由于预应力合力点升高,台座的倾覆和强度破坏风险增大。基于实际工程提出一种折线预应力施工方案,并与目前常见的2种折线预应力施工方案进行对比研究。研究和工程实践表明,所提方案可有效降低折线预应力在台座处的合力中心,进而减小预应力张拉时在台座上产生的倾覆力矩和柱底弯矩,预应力施工的安全性显著提高。采用所提方案生产的预应力梁的实际上拱度和设计值较接近,能满足工程要求。基于所提方案,预制厂将既有台座用于折线预应力梁生产时,台座改造费用可大幅度减少,具有显著经济效益。

GNSS/SINS组合导航的动基座初始对准

针对传统的最优估计对准算法(OBA)无法应用于低成本INS中的问题,本文提出了一种结合扩展卡尔曼滤波的改进OBA算法,在GNSS的辅助下实现算法对姿态误差的估计,并使其能够应用于低成本SINS系统中。该算法首先重构参考向量和观测向量,以固定积分间隔抑制零偏的积累;然后通过建立陀螺仪零偏与姿态误差之间的联系,构建新的系统状态方程,并结合GNSS输出的位置与速度构建量测方程,同时对陀螺零偏和姿态误差进行估计,并将姿态误差反馈到多矢量的构建当中;最后在仿真试验与实际跑车试验中进行验证。试验结果表明,该算法与传统OBA算法相比,可以实现动基座快速对准,且可对陀螺零偏进行估计和失准角补偿,在载体处于长时间运动状态下提高了对准精度,不使用滑动窗口积分提高了收敛速度;与FIMA算法相比,3个姿态角精度分别提升了47%、47%、51%。

立式离心泵典型故障复现试验研究

为了给立式离心泵的故障诊断提供试验和理论依据,搭建立式离心泵仿真试验台,进行立式离心泵典型故障的仿真复现试验,分析了转子不平衡、转子不对中和支座连接松动等故障的振动特性及其频谱特征.结果表明:机脚处的振动位移信号对支座连接松动故障的振动特性敏感性更高,轴系的振动信号对转子故障的振动特性敏感性更高;转子不平衡故障和转子不对中故障表现出不同的频谱特征,转子不平衡故障的频谱特征表现为1倍振动主要频率(amplitude power frequency,APF)幅值增大,且随着故障程度的增加,幅值呈现了逐渐减小的趋势,转子不对中故障的频谱特征表现为产生新的振动特征频率2APF,且随着故障程度的增大,信号幅值逐渐增大;支座连接松动故障表现为频谱图中的主频变为3APF,并出现新的2APF和1/2分数谐波频率.

基于动力学模型的机载天线座力矩补偿控制研究

当前随着载机性能的不断提升,机载雷达伺服系统需要克服载机大机动飞行时重载不平衡负载带来的力矩干扰,以确保伺服跟踪精度。文中以三轴正交串联构型的雷达天线座为例,借鉴串联机器人零力控制的力矩补偿思路,根据载机姿态信息,结合动力学分析,预估载机大机动过程中转台各轴收到的各项干扰力矩,并进行实时前馈补偿(至电流环),半实物仿真和实验证明伺服系统的抗扰动能力得到了有效提升。

三星堆出土文物蕴意解读——以唐卡画中的护法神鹰狼合体形象与三星堆出土文物青铜神坛的神兽底座为例

近年来,四川省广汉市三星堆先后出土了大量的文物。同时,在四川、云南、甘肃、青海、西藏等西南多民族交接地区也发现了大量的民间手抄文献。文章以上述相关文物与文献资料为研究基础,以唐卡画中的护法神鹰狼合体形象与三星堆青铜神坛神兽底座的文化内涵为切入点,对相关文物、文献、民俗资料进行互识、互证、互补研究。认为青藏高原及其周边地区各兄弟民族之间交往交流交融的历史至少可以上溯至3000多年以前,为铸牢中华民族共同体意识提供了客观科学的史料依据。

底部基座对重力坝强震破坏模式的影响

我国西南地区某重力坝工程的左岸非溢流坝段采用独特的方形基座设计,考虑到该地区面临较高强震风险,评估底部基座对重力坝强震破坏模式和极限承载能力的影响十分必要。采用声学单元模拟库水,以弹塑性损伤模型模拟混凝土非线性特征,构建声固耦合-损伤模拟方法,并以Koyna重力坝为算例验证其可行性。随后以带基座坝段和常规坝段为对象,研究基座对重力坝强震破坏过程的影响。结果显示,带基座坝段与常规坝段均在上游折坡、坝踵、下游坝面区域出现破坏。底部基座对重力坝破坏过程的影响有:带基座坝段出现新的破坏区;底部基座有效减弱了坝踵破坏区的深度和面积;带基座坝段在下游坝面的破坏区出现2个发展方向。在抗震极限承载能力方面,常规坝段破坏区贯通对应地震动峰值加速度为0.50g~0.55g,带基座坝段提升至0.55g~0.60g,故底部基座设计提升了非溢流坝段的极限抗震承载能力。

基于大跨度钢结构厂房的插入式钢柱柱脚施工技术

以随州新能源项目的大跨度钢结构厂房石墨化车间为例,对插入式钢柱柱脚的主要做法和技术措施进行了研究,提出了通过设置一套可拆卸的定位机构对钢柱进行定位与临时固定,解决了现有技术中钢柱定位不准确的问题。进一步介绍了插入式钢柱柱脚的新技术包括混凝土基础、底座、定位机构等,详细说明了新技术的特点、工艺流程、操作要点等,总结了新技术与现有技术相比的有益效果,为大跨度钢结构厂房的插入式钢柱柱脚施工安装提供了施工经验,可在类似工程中借鉴和推广。

固定式平台吊机基座疲劳分析研究

本文针对固定式平台吊机基座结构,计算吊机基座在起升载荷及风载荷作用下,以及不同的吊机吊臂水平旋转角度下的疲劳强度。总结一种基于风向概率分布,吊机基座疲劳分析的方法。在吊机起升载荷工况下采用S-N曲线法进行疲劳分析;在风载荷工况下根据风向概率分布图,采用S-N曲线法进行疲劳分析。然后对相同位置处的疲劳损伤值进行叠加,并与直接组合吊机起升载荷及风载荷下的疲劳损伤值结果进行对比。该分析方法可为其他在风载荷及循环载荷下的固定式平台局部结构疲劳强度分析提供参考。

数字基座赋能学校综合评价:问题挑战、评价体系与实践案例

数字基座作为教育数字化转型过程中的重要基础设施,通过集成教育云网以及数据中心、组织中心、物联中心和应用中心等核心功能形成系统底座,为学校综合评价改革提供了重要支撑。当前学校综合评价面临价值导向转变、评价标准重构、评价方法数智化等方面的挑战,数字基座赋能学校综合评价体系,即统合评价管理与发展功能提供价值引领,依托生成共性与个性统一的评价标准,基于数据采集、分析与反馈全流程整合数智评价方法,实现多主体参与协商的评价组织形式,有利于解决这一问题。未来研究与实践可以从评价指标体系多主体融通、智能代理辅助减负增效以及数智看板驱动数据集成与表征等方面出发,促使教育数字基座全面赋能综合评价改革。

大型轮轨天线座滚轮与轨道接触分析与试验研究

针对大型重载高精度轮轨天线座轨道在重载下的接触应力计算及轨道不同淬硬深度下的承载差异问题,分别采用经典Hertz理论和有限元法对冠型轮与平轨道的接触问题进行了分析计算,为验证计算结果的有效性,搭建了试验测试平台,在不同加载载荷下对轨道不同表面淬硬深度下轮轨接触斑大小和接触面变形进行了测量,并对计算结果与试验结果进行了对比分析,对静载下轮轨的承载能力、损坏形式及不同淬硬深度的影响进行了试验评估及分析,探讨了弹性接触理论与与实际加载测试结果的差异问题。相关仿真和试验方法为产品研发提供了重要参考。