High-Efficiency Dynamic Scanning Strategy for Powder Bed Fusion by Controlling Temperature Field of the Heat-Affected Zone

Improvement of fabrication efficiency and part performance was the main challenge for the large-scale powder bed fusion(PBF)process.In this study,a dynamic monitoring and feedback system of powder bed temperature field using an infrared thermal imager has been established and integrated into a four-laser PBF equipment with a working area of 2000 mm×2000 mm.The heat-affected zone(HAZ)temperature field has been controlled by adjusting the scanning speed dynamically.Simultaneously,the relationship among spot size,HAZ temperature,and part performance has been established.The fluctuation of the HAZ temperature in four-laser scanning areas was decreased from 30.85℃to 17.41℃.Thus,the consistency of the sintering performance of the produced large component has been improved.Based on the controllable temperature field,a dynamically adjusting strategy for laser spot size was proposed,by which the fabrication efficiency was improved up to 65.38%.The current research results were of great significance to the further industrial applications of large-scale PBF equipment.

Applying a salinity response function and zoning saline land for three fi eld crops: a case study in the Hetao Irrigation District, Inner Mongolia, China

Salinity is one of the major abiotic factors affecting the growth and productivity of crops in Hetao Irrigation District, China. In this study, the salinity tolerances of three local crops, wheat （Triticum aestinum L.）, maize （Zea mays L.） and sunflower （Helianthus annuus L.）, growing in 76 farm fields are evaluated with modified discount function. Salinity ecological zones appropriate for these local crops are characterized and a case study is presented for crop salinity ecological zoning. The results show that the yield reductions of wheat, maize and sunflower when grown in saline soils are attributed primarily to a reduction in spikelet number, 1 000-grain weight and seed number per head, respectively. Sunflower is the most tolerant crop among the three which had a salinity tolerance index （ST-index） of 12.24, followed by spring maize and spring wheat with ST-Indices of 9.00 and 7.43, respectively. According to the crop salinity tolerance results, the arable land in the Heping Village of this district was subdivided into four salinity ecological zones： the most suitable, suitable, sub-suitable and unsuitable zones. The area proportion of the most suitable zone for wheat, maize and sunflower within the Heping Village was 27.5, 46.5 and 77.5%, respectively. Most of the most suitable zone occurred in the western part of the village. The results of this study provide the scientific basis for optimizing the local major crop distribution and improving cultural practices management in Hetao Irrigation District.

Alternate Furrow Irrigation: A Practical Way to Improve Grape Quality and Water Use Efficiency in Arid Northwest China

Field experiments were conducted for two years to investigate the benefits of alternate furrow irrigation on fruit yield, quality and water use efficiency of grape （Vitis vinifera L. cv. Rizamat） in the arid region of Northwest China. Two irrigation treatments were included, i.e., conventional furrow irrigation （CFI, two root-zones were simultaneously irrigated during the consecutive irrigation） and alternate partial root-zone furrow irrigation （AFI, two root-zones were alternatively irrigated during the consecutive irrigation）. Results indicate that AFI maintained similar photosynthetic rate （Pn） but with a reduced transpiration rate when compared to CFI. As a consequence, AFI improved water use efficiency based on evapotranspiration （WUEEr, fruit yield over water consumed） and irrigation （WUE~, fruit yield over water irrigated） by 30.0 and 34.5%, respectively in 2005, and by 12.7 and 17.7%, respectively in 2006. AFI also increased the edible percentage of berry by 2.91-4.79% significantly in both years. Vitamin C （Vc） content content of berry was increased by 25.6-37.5%, and tritrated acidity （TA） was reduced by 9.5-18.1% in AFI. This resulted in an increased total soluble solid content （TSS） to TA ratio （TSS/TA） by 11.5-16.7% when compared to CFI in both years. Our results indicate that alternate furrow irrigation is a practical way to improve grape fruit quality and water use efficiency for irrigated crops in arid areas.

Stem flow of seed-maize under alternate furrow irrigation and double-row ridge planting in an arid region of Northwest China

Maize is widely planted throughout the world and has the highest yield of all the cereal crops. The arid region of North- west China has become the largest base for seed-maize production, but water shortage is the bottleneck for its long-term sustainability. Investigating the transpiration of seed-maize plants will offer valuable information for suitable planting and irrigation strategies in this arid area. In this study, stem flow was measured using a heat balance method under alternate furrow irrigation and double-row ridge planting. Meteorological factors, soil water content （e）, soil temperature （Ts） and leaf area （LA） were also monitored during 2012 and 2013. The diurnal stem flow and seasonal dynamics of maize plants in the zones of south side female parent （SFP）, north side female parent （NFP） and male parent （MP） were investigated. The order of stem flow rate was： SFP〉MP〉NFP. The relationships between stem flow and influential factors during three growth stages at different time scales were analyzed. On an hourly scale, solar radiation （Rs） was the main driving factor of stem flow. The influence of air temperature （Ta） during the maturity stage was significantly higher than in other periods. On a daily scale, Rs was the main driving factor of stem flow during the heading stage. During the filling growth stage, the main driving factor of NFP and MP stem flow was RH and Ts, respectively. However, during the maturity stage, the environ- mental factors had no significant influence on seed-maize stem flow. For different seed-maize plants, the main influential factors were different in each of the three growing seasons. Therefore, we identified them to accurately model the FP and MP stem flow and applied precision irrigation under alternate partial root-zone furrow irrigation to analyze major factors affecting stem flow in different scales.

宁夏引黄灌区果园生草处理对土壤理化性质的影响

本研究选用多年生黑麦草、紫花苜蓿、高羊茅、长柔毛野豌豆4种功能草种,以清耕和自然生草作为对照,探究不同生草处理对果园土壤理化性质的影响。结果表明,与多年生黑麦草生草处理相比,紫花苜蓿与长柔毛野豌豆生草处理可以显著提高0~20 cm土层土壤总孔隙度和0~20 cm、21~40 cm土层田间持水量(P<0.05),显著降低0~20 cm土层土壤容重(P<0.05)。与处理前相比,2022年10月紫花苜蓿与长柔毛野豌豆生草处理的土壤有机质含量、全盐含量、碱解氮含量(0~20 cm土层)、有效钾含量(0~20 cm土层)显著提高(P<0.05),土壤pH(0~20 cm土层)显著降低(P<0.05)。因此,在干旱和半干旱地区可以选择苜蓿和长柔毛野豌豆进行果园生草处理。本研究结果为改良果园土壤,提高水果产量提供了理论依据。

不同灌溉方式和灌水量对土壤水盐及燕麦生长特征的影响

[目的]探究不同灌溉方式和灌水量对土壤水盐变化规律及燕麦生长特征的影响,为提高盐碱地作物的生产效能和土壤水分管理提供科学参考。[方法]采用盆栽试验,设置3种灌溉方式:常规灌溉、固定单侧灌溉(fixed unilateral root zone irrigation,FURI)、交替灌溉(alternative partial root zone irrigation,APRI),3组灌水量:W_1(60%θ_f~70%θ_f,θ_f为田间持水率),W_2(70%θ_f~80%θ_f)和W_3(80%θ_f~90%θ_f),以常规灌溉作为对照,共9组交互处理。[结果](1)不同灌溉方式下,土壤各层含水率变化趋势基本一致,随灌水量增加洗盐效果越显著,常规灌溉的深层含水率总体高于其他两种灌溉方式。(2)燕麦株高、叶绿素相对含量(relative chlorophyll content of leaves,SPAD)、品质随灌水量的增加而上升,与常规灌溉相比,W_2灌溉水平下,分根交替灌溉处理的粗脂肪,粗蛋白,β-葡聚糖含量分别增加7.02%,3.76%,6.06%,但降低了燕麦叶片的SPAD值,影响其光合能力。(3)随着燕麦生育期的推进,土壤盐分均呈现不同程度的累积,分根交替灌溉的积盐率最低,同时对燕麦根系生长、水分利用效率及产量影响显著,其中根系总长、根系总表面积、根系总体积较相同灌水量(W_2)的常规灌溉分别增加6.75%,6.92%,12.5%,水分利用效率提高17.32%。[结论]采用分根交替灌溉方式下的中等灌水量(W_2)有利于提高燕麦的生产效能,对盐分累积的控制效果较好。

浔江南岸灌区工程总体方案研究

大型灌区是我国粮食和优质农产品的主要产区。新时期国家粮食安全、乡村振兴等发展战略对大型灌区建设提出了新要求。本文基于新时期灌区发展在保障粮食安全、水安全、区域水网建设、乡村振兴等方面要求,针对梧州市浔江南岸区域水资源和土地资源情况,提出浔江南岸灌区工程总体方案,构建灌区水资源配置格局和水网工程体系,满足灌区农业灌溉和城乡供水要求,保障区域粮食生产安全和供水安全,助推乡村振兴和区域水网建设。

南宁五化灌区马兰渡槽设计方案变更分析

根据全国最新“三区三线”划定成果,对原南宁市五化灌区马兰渡槽设计方案进行了变更。通过将原马兰渡槽设计方案与最新“三区三线”划定成果进行比较,提出了原址倒虹吸、原址渡槽两个设计变更方案。随后,从工程占地、地质条件、结构布置、施工运维等方面分析了各设计变更方案的优缺点,综合比选确定原址倒虹吸方案为最优设计方案。

龙云灌区新建水源工程正常蓄水位方案比选

水库正常蓄水位方案比选是确定水库规模的一个重要环节,关系到工程实施的经济性和可行性。本文以广西玉林市龙云灌区工程为例,研究提出了串联水库正常蓄水位方案比选的原则和方法,得出了经济合理的正常蓄水位成果。

基于FCM-GA灌溉供水管网减压阀布设优化

为探究灌溉供水管网中存在的漏损过高以及局部压力过大的问题,提出了一种基于FCM-GA的供水管网减压阀布设优化方法,该方法借助MATLAB、EPANET、MATLAB-EPANET-Toolkit以及PlatEMO平台等工具,对西班牙的BIN管网进行分区布置减压阀并优化阀后压力,以不同分区方案的成本与降漏效果为控制指标,筛选出最优方案。结果显示:最优方案(分5个区)将整个管网的漏损率降低至7.45%,相较初始管网降低了20.04%,降低的漏损费用可达114€/d,在减压阀服务年限内可收回成本并达到盈利,并实现对整个管网系统的压力管理,提高了管网的稳定性和可靠性,有利于减少管网事故发生。因此,基于FCM-GA的灌溉供水管网减压阀布设优化是一种安全、低成本和高效益的降漏与控压方法,在有效降低灌溉用水费用的同时,可更好地实现节水灌溉。

分根区交替灌溉在农业生产中的应用研究进展

在全球水资源日益紧缺的背景下,如何提高农业用水利用效率,对于农业可持续发展具有重要意义。分根区交替灌溉作为一种具有较好前景的高效节水灌溉技术,被认为是未来最具发展潜力的灌溉技术之一。目前,各国科技工作者围绕分根区交替灌溉对作物生长、生理的影响方面开展了大量研究,并对其节水机制进行了解析,亟待总结梳理。本文回顾了分根区交替灌溉技术的发展历程,综述了分根区交替灌溉对作物生长发育、产量及品质的影响,归纳了该技术影响作物水分利用效率的生理机制,并对分根区交替灌溉在未来的研究方向进行了展望,以期为作物分根区交替灌溉节水灌溉机理研究和节水灌溉技术的革新提供参考。

引黄灌区秋浇模式的多目标优化与时空特征评价

基于多目标在区域尺度实现河套灌区秋浇模式的优化对保证灌区粮食安全、用水安全和生态安全具有重要意义。基于率定验证后的分布式SWAP-WOFOST模型对2000-2017年河套灌区不同秋浇模式和种植条件下的模拟结果,以作物产量、水分生产力(Water Productivity,WP)、地下水埋深(Groundwater Depth,GWD)、土壤含水量(Soil Water Content,SWC)和土壤含盐量(Soil Salt Content,SSC)为评价指标,通过AHP-CRITIC-熵值法-TOPSIS综合评价法,分别对河套灌区3种主要作物(春小麦、春玉米和向日葵)种植条件下适宜的秋浇模式进行优选和评价,并对3种主要作物在推荐秋浇模式下的种植结构进行初步区划。结果显示:在推荐的秋浇模式下河套灌区3种作物的多年平均产量分别为4945、8332和3496 kg/hm^(2),多年平均WP分别为1.15、1.82和1.04 kg/m^(3),节省秋浇引黄灌溉水量约14.8%~30.7%。基于推荐的秋浇模式区划后春小麦、春玉米和向日葵的种植面积分别占灌区总面积的21.1%、37.8%和41.1%,在此种植结构下可节省约3.04亿m^(3)的秋浇引黄灌溉水量。

滴灌灌水量对风沙土大豆根区硝态氮及水分分布的影响

为合理进行风沙土地区灌溉管理,将水肥控制在根区范围内并满足大豆生长需求,以灌水量为试验因素,基于作物冠层蒸发皿蒸发量设置0.4(W1)、0.6(W2)、0.8(W3)、1.0 E_(pan)(W4)和1.2 E_(pan)(W5)5个灌溉水平,研究不同灌水量对大豆根区硝态氮和水分分布的影响。结果表明:增加灌水量会使土壤水分入渗深度增加10~30 cm,增大根区土壤水分分布的不均匀性,苗期W5处理剖面水分平均值较W1处理增大40.22%,W4、W5处理能够维持大豆根区6%~7%的土壤含水率。硝态氮有明显表聚现象,随着灌水量的增大,淋洗深度增加且不均匀性增大,根区土壤硝态氮平均含量降低,当灌水量高于1.0 E_(pan)时,硝态氮含量低于10 mg·kg^(-1)。W2、W3和W4处理能保证大豆根区在生育前、中、后期处于15~22 mg·kg^(-1)的硝态氮浓度区间,垂直方向上灌水量与硝态氮呈负相关关系。风沙土土壤剖面含水率均在4%~10%之间,灌水量是影响风沙土硝态氮含量和分布的主要因素之一;各处理硝态氮含量在10~30 mg·kg^(-1)之间。综合考虑作物对根区土壤水分和硝态氮含量的需求,以及土壤水分和硝态氮在根层的分布特征,推荐灌溉水量为1.0 E_(pan)。

Discovery and petroleum geological significance of delta in the third member of Oligocene Lingshui Formation in southern Baodao Sag,Qiongdongnan Basin,South China Sea

Based on the 3D seismic data and the analysis and test data of lithology,electricity,thin sections and chronology obtained from drilling of the Qiongdongnan Basin,the characteristics and the quantitative analysis of the source-sink system are studied of the third member of the Upper Oligocene Lingshui Formation(Ling 3 Member)in the southern fault step zone of the Baodao Sag.First,the YL10 denudation area of the Ling 3 Member mainly developed two fluvial systems in the east and west,resulting in the formation of two dominant sand transport channels and two delta lobes in southern Baodao Sag,which are generally large in the west and small in the east.The evolution of the delta has experienced four stages:initiation,prosperity,intermittence and rejuvenation.Second,the source-sink coupled quantitative calculation is performed depending on the parameters of the delta sand bodies,including development phases,distribution area,flattening thickness,area of different parent rocks,and sand-forming coefficient,showing that the study area has the material basis for the formation of large-scale reservoir.Third,the drilling reveals that the delta of the Ling 3 Member is dominated by fine sandstone,with total sandstone thickness of 109-138 m,maximum single-layer sandstone thickness of 15.5-30.0 m,and sand-to-strata ratio of 43.7%-73.0%,but the physical properties are different among the fault steps.Fourth,the large delta development model of the small source area in the step fault zone with multi-stage uplift is established.It suggests that the episodic uplift provides sufficient sediments,the fluvial system and watershed area control the scale of the sand body,the multi-step active fault steps dominate the sand body transport channel,and local fault troughs decide the lateral propulsion direction of the sand body.The delta of the Ling 3 Member is coupled with fault blocks to form diverse traps,which are critical exploration targets in southern Baodao Sag.

银川平原永宁引黄灌区包气带硝态氮运移特征

为研究硝态氮在银川平原永宁引黄灌区的运移特征,在永宁县杨和镇观桥村种植园内选择一处剖面建立包气带原位监测点,选取7个土壤深度对其进行为期两年的监测,其中2019年为裸地,2020年种植玉米。经过研究发现:随着灌溉事件的发生,硝态氮随着土壤水向下运动并且发生累积和淋失,其中裸地在100 cm处发生明显累计,淋失量为127.8 kg/hm^(2);种植玉米期间在150 cm处发生明显累积,淋失量48.8 kg/hm^(2)。硝态氮的运移、累积和淋失明显受到灌溉、植物生长作用的影响。

Investigation on lateral dispersion characteristics of fuel particles in dense phase zone of a large-scale circulating fluidized bed boiler under combustion conditions

The dispersion characteristics of fuel particles in the dense phase zone in circulating fluidized bed(CFB)boilers have an important influence on bed temperature distribution and pollutant emissions.However,previous research in literature was mostly on small-scale apparatus,whose results could not be applied directly to large-scale CFB with multiple dispersion sources.To help solve this problem,we proposed a novel method to estimate the lateral dispersion coefficient(Dx)of fuel particles under partial coal cut-off condition in a 35o MW supercritical CFB boiler based on combustion and dispersion models.Meanwhile,we carried out experiments to obtain the Dx in the range of 0.1218-0.1406 m2/s.Numerical simulations were performed and the influence of operating conditions and furnace structure on fuel dispersion characteristics was investigated,the simulation value of Dx was validated against experimental data.Results revealed that the distribution of bed temperature caused by the fuel dispersion was mainly formed by char combustion.Because of the presence of intermediate water-cooled partition wall,the mixing and dispersion of fuel and bed material particles between the left and right sides of the furnace were hindered,increasing the non-uniformity of the bed temperature near furnace front wall.

龙江河谷灌区需水预测分析

龙江河谷灌区开发任务为农业灌溉及城乡供水,打造龙江清水廊道,保障区域粮食生产安全和人饮供水安全,为少数民族地区巩固拓展脱贫攻坚成果、促进乡村振兴创造条件。本文对灌区内的农业灌溉、城区、村镇用水进行预测,预测成果可为灌区工程规模、水资源优化配置和供水决策提供依据。

大型长距离输水灌区工程测量技术研究

针对大型长距离输水灌区工程测量的重点和难点,从控制网建立、地形图测绘两个关键节点,探析如何利用现代化测绘技术(平面控制网观测利用北斗导航卫星技术、利用自编水准数据处理小软件提高高程控制网建立的效率,地形图测绘采用低空无人机航测、激光雷达测量技术,外业调绘加载高精度大地水准面模型提高高程测量精度等)快速、高效、高质量完成测量任务。

典型引黄灌区包气带与地下水动态响应试验

【目的】开展银川平原引黄灌溉引起的包气带和地下水的动态响应试验,研究“灌溉水-包气带水-地下水”的转换过程和规律。【方法】以典型引黄灌区水田为研究对象,运用水文地质学、土壤水动力学等学科理论对原位试验观测资料数值分析,借助Origin、SPSS等统计分析软件进行数据处理,利用Hydrus-1D、Surfer等数值模拟软件进行拟合和插值分析。【结果】结果得出,灌溉过程中包气带各埋深层位的水分和负压变化呈显著相关性,相关系数达0.9以上;运用Hydrus-1D拟合田间土壤水分特征曲线,发现叠加各埋深层位可得到较连续的拟合曲线;在多次灌溉入渗试验中,第1次灌溉入渗引起的地下水动态响应最快,灌溉后响应时间为388.8 min;运用地下水灌溉响应法定量测算灌溉入渗能力,算得田间灌溉入渗系数均值为0.202;对地下水位动态进行插值分析,发现回灌逐步形成“水丘”中心,地下水流场也随之发生变化;通过地下水补给源项分析,引黄灌区内灌溉水对地下水的年灌溉补给贡献率达79%。【结论】通过原位田间试验,进一步厘清引黄灌区的包气带特性和地下水响应过程,发现引黄灌溉对灌区地下水的补给和流场特征有着决定性的作用,为提高引黄水量利用率和包气带-地下水资源评估、管理及调控提供一定科学支撑。

南宁市邕北灌区外引骨干水源方案比选

拟建的南宁市邕北灌区位于南宁市城区北部,郁江干流与红水河干流之间的区域。根据周边河流水系及已建水利工程分布情况,灌区外引骨干水源初拟岩滩水电站引水、大化水电站引水、分散提水3个方案。本文根据各方案的水资源条件、工程地质条件、工程布置方案、工程施工条件、经济指标以及运行管理等方面进行综合比选,初步选定最优的外引骨干水源方案。