一种S波段雷达通信电子战多功能宽带DAM的设计

本文创新性地提出了一种S波段多功能宽带DAM,首先介绍了该型DAM的顶层架构设计,接着介绍了各个功能组成模块的设计过程,最后给出了该型DAM的指标实现情况。该型DAM可以分时实现雷达、通信及电子战功能,最大瞬时带宽可达200MHz,支持任意波形产生,在多功能综合射频系统中具有良好的应用前景。

3个李品种(系)芽需冷量的研究及休眠相关DAM基因的表达分析

【目的】探究3个李(Prunus)品种(系)的芽休眠和需冷量的差异及DAM基因表达与芽休眠的关系。【方法】调查统计了3个李品种(系)需冷量与萌芽率,采用生物信息学的方法对李的DAM基因进行鉴定,并用qRT-PCR对3个品种(系)李的DAM基因在芽的不同休眠阶段表达分析。【结果】7.2℃模型、0~7.2℃模型、犹他模型下“晚熟羌脆李”的需冷量均高于‘羌脆李’和‘脆红李’,且3个需冷量统计模型下‘羌脆李’和‘脆红李’的需冷量相同。鉴定了6个DAM基因(Pd DAM1、Pd DAM2、Pd DAM3、Pd DAM4、Pd DAM5、Pd DAM6),但花芽与叶芽内休眠期与内休眠解除期(需冷区间)高表达基因都为DAM5,且在休眠解除期DAM基因的相对表达量均呈下降趋势。【结论】揭示了3个李品种(系)的花芽与叶芽需冷量的差异,筛选出与休眠解除最相关的DAM基因,结果为李芽休眠及熟期调节提供理论依据。

葡萄休眠相关基因DAMs的克隆分析及对单氰胺的响应

DAM基因是真核生物转录因子之一,在木本果树的芽休眠中起着重要的调控作用,且在不同物种间数量不同。以‘水晶’葡萄为试材,于冬芽休眠期间采集枝条后均匀涂抹2.5%单氰胺,在处理后的不同时间采集冬芽,用于克隆VvDAMs基因序列,对其进行生物信息学和荧光定量分析,并测定冬芽激素含量。结果表明,克隆获得的VvDAM1、VvDAM2和VvDAM3基因的开放阅读框的长度分别为690、696、702 bp,分别编码229、231、233个氨基酸和1个终止密码子,相对分子量分别为25.96、26.76、25.99 kD,理论等电点分别为7.71、10.49、9.10;三者的二级结构形式均呈现α-螺旋>无规则卷曲>延伸链的规律;VvDAM1、VvDAM2、VvDAM3氨基酸序列上有一定的同一性,VvDAM1与欧洲李PsDAM1、VvDAM2与樱桃李PcDAM2、VvDAM3与李PsDAM3之间的同源性均达到98%以上;此外,冬芽休眠解除期间,VvDAM 1、VvDAM 2、VvDAM 3基因的表达量逐渐下降,IAA、GA3+4、ZR的含量和GA3+4/ABA逐渐上升,ABA含量和IAA/ZR逐渐下降,单氰胺处理后使其变化提前且幅度增大,从而使芽提前萌发,为葡萄冬芽破眠、早熟栽培等提供理论依据和实践意义。

Numerical investigation of hydro-morphodynamic characteristics of a cascading failure of landslide dams

A cascading failure of landslide dams caused by strong earthquakes or torrential rains in mountainous river valleys can pose great threats to people’s lives,properties,and infrastructures.In this study,based on the three-dimensional Reynoldsaveraged Navier-Stokes equations(RANS),the renormalization group(RNG)k-εturbulence model,suspended and bed load transport equations,and the instability discriminant formula of dam breach side slope,and the explicit finite volume method(FVM),a detailed numerical simulation model for calculating the hydro-morphodynamic characteristics of cascading dam breach process has been developed.The developed numerical model can simulate the breach hydrograph and the dam breach morphology evolution during the cascading failure process of landslide dams.A model test of the breaches of two cascading landslide dams has been used as the validation case.The comparison of the calculated and measured results indicates that the breach hydrograph and the breach morphology evolution process of the upstream and downstream dams are generally consistent with each other,and the relative errors of the key breaching parameters,i.e.,the peak breach flow and the time to peak of each dam,are less than±5%.Further,the comparison of the breach hydrographs of the upstream and downstream dams shows that there is an amplification effect of the breach flood on the cascading landslide dam failures.Three key parameters,i.e.,the distance between the upstream and the downstream dams,the river channel slope,and the downstream dam height,have been used to study the flood amplification effect.The parameter sensitivity analyses show that the peak breach flow at the downstream dam decreases with increasing distance between the upstream and the downstream dams,and the downstream dam height.Further,the peak breach flow at the downstream dam first increases and then decreases with steepening of the river channel slope.When the flood caused by the upstream dam failure flows to the downstream dam,it can produce a surge wave that overtops and erodes the dam crest,resulting in a lowering of the dam crest elevation.This has an impact on the failure occurrence time and the peak breach flow of the downstream dam.The influence of the surge wave on the downstream dam failure process is related to the volume of water that overtops the dam crest and the erosion characteristics of dam material.Moreover,the cascading failure case of the Xiaogangjian and Lower Xiaogangjian landslide dams has also been used as the representative case for validating the model.In comparisons of the calculated and measured breach hydrographs and final breach morphologies,the relative errors of the key dam breaching parameters are all within±10%,which verify the rationality of the model is applicable to real-world cases.Overall,the numerical model developed in this study can provide important technical support for the risk assessment and emergency treatment of failures of cascading landslide dams.

Numerical three-dimensional modeling of earthen dam piping failure

A physically-based numerical three-dimensional earthen dam piping failure model is developed for homogeneous and zoned soil dams.This model is an erosion model,coupled with force/moment equilibrium analyses.Orifice flow and two-dimensional(2D)shallow water equations(SWE)are solved to simulate dam break flows at different breaching stages.Erosion rates of different soils with different construction compaction efforts are calculated using corresponding erosion formulae.The dam's real shape,soil properties,and surrounding area are programmed.Large outer 2D-SWE grids are used to control upstream and downstream hydraulic conditions and control the boundary conditions of orifice flow,and inner 2D-SWE flow is used to scour soil and perform force/moment equilibrium analyses.This model is validated using the European Commission IMPACT(Investigation of Extreme Flood Processes and Uncertainty)Test#5 in Norway,Teton Dam failure in Idaho,USA,and Quail Creek Dike failure in Utah,USA.All calculated peak outflows are within 10%errors of observed values.Simulation results show that,for a V-shaped dam like Teton Dam,a piping breach location at the abutment tends to result in a smaller peak breach outflow than the piping breach location at the dam's center;and if Teton Dam had broken from its center for internal erosion,a peak outflow of 117851 m'/s,which is 81%larger than the peak outflow of 65120 m3/s released from its right abutment,would have been released from Teton Dam.A lower piping inlet elevation tends to cause a faster/earlier piping breach than a higher piping inlet elevation.

Sliding and damming properties of granular debris with different geometric configurations and grain size distributions

Granular debris plays a significant role in determining damming deposit characteristics. An indepth understanding of how variations in grain size distribution(GSD) and geometric configurations impact the behavior of granular debris during the occurrence of granular debris is essential for precise assessment and effective mitigation of landslide hazards in mountainous terrains. This research aims to investigate the impact of GSD and geometric configurations on sliding and damming properties through laboratory experiments. The geometric configurations were categorized into three categories based on the spatial distribution of maximum volume: located at the front(Type Ⅰ), middle(Type Ⅱ), and rear(Type Ⅲ) of the granular debris. Our experimental findings highlight that the sliding and damming processes primarily depend on the interaction among the geometric configuration, grain size, and GSD in granular debris. Different sliding and damming mechanisms across various geometric configurations induce variability in motion parameters and deposition patterns. For Type Ⅰ configurations, the front debris functions as the critical and primary driving component, with energy dissipation primarily occurring through inter-grain interactions. In contrast, Type Ⅱ configurations feature the middle debris as the dominant driving component, experiencing hindrance from the front debris and propulsion from the rear, leading to complex alterations in sliding motion. Here, energy dissipation arises from a combination of inter-grain and grain-substrate interactions. Lastly, in Type Ⅲ configurations, both the middle and rear debris serve as the main driving components, with the rear sliding debris impeded by the front. In this case, energy dissipation predominantly results from grainsubstrate interaction. Moreover, we have quantitatively demonstrated that the inverse grading in damming deposits, where coarse grain moves upward and fine grain moves downward, is primarily caused by grain sorting due to collisions among the grains and between the grain and the base. The impact of grain on the horizontal channel further aids grain sorting and contributes to inverse grading. The proposed classification of three geometric configurations in our study enhances the understanding of damming properties from the view of mechanism, which provides valuable insights for related study about damming granular debris.

Long-Term Performance and Microstructural Characterization of Dam Concrete in the Three Gorges Project

This study investigates the long-term performance of laboratory dam concrete in different curing environments over ten years and the microstructure of 17-year-old laboratory concrete and actual concrete cores drilled from the Three Gorges Dam.The mechanical properties of the laboratory dam concrete,whether cured in natural or standard environments,continued to improve over time.Furthermore,the laboratory dam concrete exhibited good resistance to diffusion and a refined microstructure after 17 years.However,curing and long-term exposure to the local natural environment reduced the frost resistance.Microstructural analyses of the laboratory concrete samples demonstrated that moderate-heat cement and fine fly ash(FA)particles were almost fully hydrated to form compact micro structures consisting of large quantities of homogeneous calcium(alumino)silicate hydrate(C-(A)-S-H)gels and a few crystals.No obvious interfacial transition zones were observed in the microstructure owing to the longterm pozzolanic reaction.This dense and homogenous microstructure was the crucial reason for the excellent long-term performance of the dam concrete.A high FA volume also played a significant role in the microstructural densification and performance growth of dam concrete at a later age.The concrete drilled from the dam surface exhibited a loose microstructure with higher microporosity,indicating that concrete directly exposed to the actual service environment suffered degradation caused by water and wind attacks.In this study,both macro-performance and microstructural analyses revealed that the application of moderate-heat cement and FA resulted in a dense and homogenous microstructure,which ensured the excellent long-term performance of concrete from the Three Gorges Dam after 17 years.Long-term exposure to an actual service environment may lead to microstructural degradation of the concrete surface.Therefore,the retained long-term dam concrete samples need to be further researched to better understand its microstructural evolution and development of its properties.

Health diagnosis of ultrahigh arch dam performance using heterogeneous spatial panel vector model

Currently,more than ten ultrahigh arch dams have been constructed or are being constructed in China.Safety control is essential to long-term operation of these dams.This study employed the flexibility coefficient and plastic complementary energy norm to assess the structural safety of arch dams.A comprehensive analysis was conducted,focusing on differences among conventional methods in characterizing the structural behavior of the Xiaowan arch dam in China.Subsequently,the spatiotemporal characteristics of the measured performance of the Xiaowan dam were explored,including periodicity,convergence,and time-effect characteristics.These findings revealed the governing mechanism of main factors.Furthermore,a heterogeneous spatial panel vector model was developed,considering both common factors and specific factors affecting the safety and performance of arch dams.This model aims to comprehensively illustrate spatial heterogeneity between the entire structure and local regions,introducing a specific effect quantity to characterize local deformation differences.Ultimately,the proposed model was applied to the Xiaowan arch dam,accurately quantifying the spatiotemporal heterogeneity of dam performance.Additionally,the spatiotemporal distri-bution characteristics of environmental load effects on different parts of the dam were reasonably interpreted.Validation of the model prediction enhances its credibility,leading to the formulation of health diagnosis criteria for future long-term operation of the Xiaowan dam.The findings not only enhance the predictive ability and timely control of ultrahigh arch dams'performance but also provide a crucial basis for assessing the effectiveness of engineering treatment measures.

Impacts of artificial dams on terrestrial water storage changes and the Earth's elastic load response during 1950-2016: A case study of medium and large reservoirs in Chinese mainland

The construction of dams for intercepting and storing water has altered surface water distributions, landsea water exchanges, and the load response of the solid Earth. The lack of accurate estimation of reservoir properties through the land surface and hydrological models can lead to water storage simulation and extraction errors. This impact is particularly evident in many artificial reservoirs in China. The study aims to comprehensively assess the spatiotemporal distribution and trends of water storage in medium and large reservoirs(MLRs) in Chinese mainland during 1950-2016, and to investigate the gravity,displacement, and strain effects induced by the reservoir mass concentration using the load elasticity theory. In addition, the impoundment contributions of MLRs to the relative sea level changes were assessed using a sea-level equation. The results show impoundment increases in the MLRs during1950-2016, particularly in the Yangtze River(Changjiang) and southern basins, causing significant elastic load effects in the surrounding areas of the reservoirs and increasing the relative sea level in China's offshore. However, long-term groundwater estimation trends are overestimated and underestimated in the Yangtze River and southwestern basins, respectively, due to the neglect of the MLRs impacts or the uncertainty of the hydrological model's output(e.g., soil moisture, etc.). The construction of MLRs may reduce the water mass input from land to the ocean, thus slowing global sea level rise. The results of the impact of human activities on the regional water cycle provide important references and data support for improving the integration of hydrological models, evaluating Earth's viscoelastic responses under longterm reservoir storage, enhancing in-situ and satellite geodetic measurements, and identifying the main factors driving sea level changes.

DAM中波发射机A/D转换板故障分析和处理

阐述数字幅度调制(Digital Amplitude Modulation,DAM)中波发射机模数(Analog to Digital,A/D)转换原理、A/D转换板主要组成部分及其作用,列举A/D转换板在实际运行中出现的常见故障案例,对常见故障给出分析和处理方法,为今后该板的故障分析和处理工作提供参考。

Erosion Rates in Dam Catchments in Jordan—Effects of Topography, Geology, and Urbanizations

Erosion as a natural process produces soils, which are very important natural resources for the fest land plant- and animal kingdoms. Loss of the soil cover reduces agricultural production, biodiversity, and the role of soil as a filter for infiltrating water to replenish the groundwater. It also threatens the food supplies. The knowledge of erosion rates of rocks and terrains is important for developing proactive measures to protect soils from erosion and loss. In this study, erosion rates of catchment areas were calculated based on dams’ catchment extensions and the sediment loads transported by flood flows into dams’ lakes. The study results show that the chemically, via floodwater, transported quantities of materials are negligible compared to the solid materials transported by the water. It calculates erosion rates ranging from 0.013 to 0.212 mm/yr (13 - 212 m/106 yr) for the different catchment areas. Erosion rates in Jordan are, generally, higher than those calculated for the different parts of the world ranging from 2.5 to 60 m/106 yr. This fact can be explained by the very steep topography, calcareous rock cover of the catchment areas and the barren rock exposures.

DAM10KW中波广播发射机维护实操案例分析

本文主要阐述3个DAM10kW中波广播发射机维护实操案例,这些维护案例均来源于实际工作当中,其中每一步的维修理念都是根据发射机的故障现象对照图纸仔细研判,并通过一些测试设备一步一步详细进行的维护经验总结,具有可研性和参考价值。

DAM 10 kW中波广播发射机的技术特点和维护策略

随着我国社会现代化建设进程不断加快,在广播事业发展过程中对中波广播发射机的应用越来越普遍。DAM 10kW中波广播发射机应用了先进的数字调制和功率合成技术,可以有效提高中波发射机的整机效率,工作性能也比较稳定,操作比较方便。本文通过对DAM 10kW中波广播发射机运行原理和优势进行分析,明确了在DAM 10kW中波广播发射机运行过程中的技术特点。并基于技术特点制定了发射机精细化管理策略,以进一步提高发射机的运行稳定性和安全性,避免发射机在运行过程中出现故障问题。

Deformation prediction model of concrete face rockfill dams based on an improved random forest model

The unique structure and complex deformation characteristics of concrete face rockfill dams(CFRDs)create safety monitoring challenges.This study developed an improved random forest(IRF)model for dam health monitoring modeling by replacing the decision tree in the random forest(RF)model with a novel M5'model tree algorithm.The factors affecting dam deformation were preliminarily selected using the statistical model,and the grey relational degree theory was utilized to reduce the dimensions of model input variables.Finally,a deformation prediction model of CFRDs was established using the IRF model.The ten-fold cross-validation method was used to quantitatively analyze the parameters affecting the IRF algorithm.The performance of the established model was verified using data from three specific measurement points on the Jishixia dam and compared with other dam deformation prediction models.At point ES-10,the performance evaluation indices of the IRF model were superior to those of the M5'model tree and RF models and the classical support vector regression(SVR)and back propagation(BP)neural network models,indicating the satisfactory performance of the IRF model.The IRF model also outperformed the SVR and BP models in settlement prediction at points ES2-8 and ES4-10,demonstrating its strong anti-interference and generalization capabilities.This study has developed a novel method for forecasting and analyzing dam settlements with practical significance.Moreover,the established IRF model can also provide guidance for modeling health monitoring of other structures.

Rapid prediction models for 3D geometry of landslide dam considering the damming process

The geometry of a landslide dam plays a critical role in its stability and failure mode,and is influenced by the damming process.However,there is a lack of understanding of the factors that affect the 3D geometry of a landslide dam.To address this gap,we conducted a study using the smoothed particle hydrodynamics numerical method to investigate the evolution of landslide dams.Our study included 17 numerical simulations to examine the effects of several factors on the geometry of landslide dams,including valley inclination,sliding angle,landslide velocity,and landslide mass repose angle.Based on this,three rapid prediction models were established for calculating the maximum height,the minimum height,and the maximum width of a landslide dam.The results show that the downstream width of a landslide dam remarkably increases with the valley inclination.The position of the maximum dam height along the valley direction is independent of external factors and is always located in the middle of the landslide width area.In contrast,that position of the maximum dam height across the valley direction is significantly influenced by the sliding angle and landslide velocity.To validate our models,we applied them to three typical landslide dams and found that the calculated values of the landslide dam geometry were in good agreement with the actual values.The findings of the current study provide a better understanding of the evolution and geometry of landslide dams,giving crucial guidance for the prediction and early warning of landslide dam disasters.

Characteristics of gully bed scour and siltation between check dams

Check dams are the most commonly used engineering measure for debris flow control worldwide.The scour and siltation characteristics between dams are important factors affecting dam design.In this study,classical dimensional analysis of the variables that influence the development of gully bed scour and siltation was carried out.Flume experiments were conducted to examine the influence characteristics of opening width,flume slope,debris flow density,and opening rate on the characteristics of gully bed scour and siltation.The influential characteristics of variables on the dimensionless scour depth,scour length,siltation length,scour volume and siltation volume were obtained.The experiments showed that,with an increase in the relative opening from 1.5 to 2.5,scour depth increased by 7.4%,scour length decreased by 11.2%,siltation length increased by 22.0%,scour volume decreased by 4.7%and siltation volume increased by 22.0%.With an increase in flume gradient from 0.105 to 0.213,scour depth,siltation length and siltation volume increased by 40.0%,65.9%and 65.9%,respectively,and scour length decreased by 20.1%.With an increase in sediment concentration from 0.303 to 0.545,siltation length and siltation volume increased by 15.4%and 15.4%,respectively,and scour depth,scour length and scour volume decreased by 9.6%,9.1%and 17.8%,respectively.As opening rate increased from 0.08 to 0.32,siltation length and siltation volume increased by 33.3%and 33.3%,respectively,and scour depth,scour length and scour volume decreased by 5.4%,13.7%and 18.4%,respectively.The results showed that the flume gradient was the most influential factor on scour depth,scour length,siltation length and siltation volume,and the sediment concentration was the most influential factor on scour volume.Then,according to the experimental data,some empirical formulas predicting scour depth,scour length,siltation length,scour volume and siltation volume were obtained.The error between the computed values according to the formulas in this paper and the observed values was within±10%.These research results may provide a technological basis for window dam design in debris flow disaster prevention and mitigation.

DAM中波发射机电源电路工作原理与常见故障分析

DAM中波发射机电源故障为多发故障,当出现电源故障时,多数情况下都有相应的故障显示,技术人员可以根据故障显示进行相应的检查处理,但有些电源故障没有故障指示,技术人员只能凭维修经验来分析查找故障原因,延误了维修时间。本文以陕西762厂生产的10k WDAM发射机为例,对电源电路的组成和工作原理进行剖析,并在分析故障案例的基础上论述电源故障的维修方法和技巧,与业内同行共分享。

薄壁DAM盒体精密熔模铸造工艺研究

某DAM铝合金盒体具有结构复杂、壁薄、内腔安装面精度要求高以及批量大等特点,采用现有的机械加工方法存在加工死角,但结合电火花工序又会造成加工成本高、周期长且生产效率低。该文研究了采用精密熔模铸造方法制造该DAM盒体的可行性,从总体工艺路线设计、材料选择、结构工艺性优化和熔模铸造工艺等方面进行了分析和样件验证。样件检测结果表明,采用精密熔模铸造方法制备出的DAM盒体铸件质量、尺寸精度、化学成分均能满足要求,具备批量生产可行性。该研究结果可为DAM盒体类零件的设计和低成本制造提供参考。

DAM大气模型构建与验证

根据热层物理、经验模型原理和代码分析,研究模型构建方法。进而剖析国内热层大气探测和热层模型构建现状,提出存在的困难和未来的发展思路。以GOST模型为基础,分析模型的工作机制、地磁扰动期大气密度预报误差来源和密切相关的模型系数,推导模型密度对相关模型系数的偏导数矩阵。利用天基实测密度,有针对性地构建磁暴期大气模型(DAM)。并通过独立于建模的实测密度数据,验证DAM模型性能。统计发现,地磁活动指数Ap介于100~132时GOST,MSIS00和DAM模型的相对误差均值依次为64.32%,-176.72%,-14.83%。Ap指数80~132时,相对误差均值对应为77.44%,-136.74%,-14.14%,DAM模型性能较GOST和MSIS00均有明显提升。证明通过搭建大气模型框架和实测密度数据估计模型参数的建模方法是可行和有效的。

Flood risk assessment of check dams in the Wangmaogou watershed on the Loess Plateau of China

Check dams have been widely used in China’s Loess Plateau region due to their effectiveness in erosion and flood control.However,the safety and stability of the check dam decrease with the operation process,which increases the probability of dam failure during flood events and threatens local residents’ life and property.Thus,this study simulated flood process of the check dam failure in the Wangmaogou watershed in Yulin City,Shaanxi Province,China,calculated different types of inundation losses based on the flood inundation area within the watershed,and determined the number of key flood protection check dams by classifying the flood risk levels of the check dams.The results showed that 5 dams in the watershed were subject to overtopping during different rainfall return periods,which was related to their flood discharge capacity.Dam failure flood process showed a rapid growth trend followed by slow decrease,and the time of flood peak advanced with increase in the return period.After harmonization of evaluation scales,the magnitude of flood inundation losses can be ranked as:economic losses(212.409 million yuan) > life losses(10.368 million yuan) > ecological losses(6.433 million yuan).The risk value for both individual dams and the whole dam system decreases as the return period increases.The number of key flood protection check dams in the Wangmaogou watershed was 2,3,3,3,4,and 5 for floods with return periods of 10,20,30,50,100,and 200 years,respectively.The results provided a theoretical basis for the safe operation and risk evaluation of check dams in the Loess Plateau Hills watershed.