Biophysical warming patterns of an open-top chamber and its short-term influence on a Phragmites wetland ecosystem in China

Passive-warming, open-top chambers(OTCs) are widely applied for studying the effects of future climate warming on coastal wetlands. In this study, a set of six OTCs were established at a Phragmites wetland located in the Yellow River Delta of Dongying City, China. With data collected through online transmission and in-situ sensors, the attributes and patterns of realized OTCs warming are demonstrated.The authors also quantified the preliminary influence of experimental chamber warming on plant traits.OTCs produced an elevated average air temperature of 0.8°C(relative to controls) during the growing season(June to October) of 2018, and soil temperatures actually decreased by 0.54°C at a depth of 5 cm and 0.46°C at a depth of 30 cm in the OTCs. Variations in diel patterns of warming depend greatly on the heat sources of incoming radiation in the daytime versus soil heat flux at night. Warming effects were often larger during instantaneous analyses and influenced OTCs air temperatures from-2.5°C to 8.3°C dependent on various meteorological conditions at any given time, ranging from cooling influences from vertical heat exchange and vegetation to radiation-associated warming. Night-time temperature depressions in the OTCs were due to the low turbulence inside OTCs and changes in surface soilatmosphere heat transfer. Plant shoot density, basal diameter, and biomass of Phragmites decreased by23.2%, 6.3%, and 34.0%, respectively, under experimental warming versus controls, and plant height increased by 4.3%, reflecting less carbon allocation to stem structures as plants in the OTCs experienced simultaneous wind buffering. While these passive-warming OTCs created the desired warming effects both to the atmosphere and soils, pest damages on the plant leaves and lodging within the OTCs were extensive and serious, creating the need to consider control options for these chambers and the replicated OTCs studies underway in other Chinese Phragmites marshes(Panjin and Yancheng).

Impacts of ozone on the biomass and yield of rice in open top chambers

The impacts of different 03 concentration on the biomass and yield of rice were studied by using OTC-1 open-top chambers. Experimental treatments included the activated charcoal-filtered air. (CFA), 50 nl/L (CF50), 100 nl/L ( CF100) and 200 nl/L (CF200) concentrations of O-3. The O-3 treatments significantly decreased the total biomass per plant. The. elevated O-3 exposure resulted in a more decrease in the root growth than in the shoot growth. Assessments of yield characteristics at the final harvest revealed an O-3-induced decrease in the number of grains per plant, resulting from fewer ears per plant, fewer grains per ear and more unfilled grains per ear. The 1000 grain dry weight and the harvest index (HI) were not changed significantly under 50 nl/L or 100 nl/L O-3 exposure, but reduced by 17.0% and 4.8% by 200nl/L O-3 treatment, respectively. Compared to the CFA treatment, CF50, CF100 and CF200 treatments caused a 8.2%, 26.1%, 49.1% decrease of the grain yield per plant, and a 14.2%, 31.7%, 51.7% decrease of the total biomass per plant, respectively. Linear regression showed that the 7h - daily mean O-3 concentration exposure for 3 months ( July-September) and AOT40 ( cunulative exposure accumulation over threshold 40 nl/L) were well correlated with the relative grain yield. A yield loss of 10% was estimated to be at 46.9 nl/L O-3 for 7h-daily mean O-3 concentration exposure or at 12930nl/(L(.)h) O-3 for AOT40.

Turbulence statistics of natural airflow within a large Open Top Chamber

The turbulence statistics parameters （variables） of natural airflow within a large Open Top Chamber （OTC）, 4 m in high height and 3 m in diameter, were measured with a three-dimensional ultrasonic anemometer/thermometer at Research Station of Changbai Mountain Forest Ecosystems Jilin Province, China in May 2004, for improving the field application of OTP. Results showed that because of the physical limitation, turbulence within OTC exhibited unique map compared with that of natural environments. There were clear daily pat- terns for most parameters. Turbulence here seemed to be isotropic and closely linked at all directions. Shape of eddies looked like a ＇cylinder＇ which was very similar to the shape of OTC. Continuous airflow was always interpreted by large scale eddies from top of OTC and showed high interactive intermittence at all directions.

Anterior Chamber Depth Changes in Narrow Iridocorneal Angles after Phacoemulsification

Background: The burden of cataract and glaucoma has been increasing. Primary angle closure occurs as a result of crowded anterior segment anatomy causing appositional contact between peripheral iris and trabecular meshwork. Lens extraction has been proposed as a method of deepening anterior chamber and managing intraocular pressure. Purpose: To assess changes in anterior chamber depth after phacoemulsification with intraocular lens implantation in narrow angle eyes. Design: Prospective controlled trial (before-after) study. Method: The study was conducted from March 2015 to August 2017 among the patients of department of Ophthalmology of BSMMU who were diagnosed as cataract with narrow angles. Anterior chamber angle grading of 2 or less (Shaffer grading) in 3 or more quadrants was considered narrow angle (NA). The purposive type sampling technique was applied to collect sample from the study population, as per inclusion and exclusion criteria. Complete clinical evaluation including history, physical examination, relevant ocular examinations and systemic examinations were performed. In this prospective study, subjects underwent phacoemulsification with foldable lens implantation. A scan ultrasonography was performed preoperatively and 10th and 30th postoperative days of surgery. Results: Thirty eyes of 29 patients included in the study, male: female ratio was 1:1, with an overall mean age of 62.03 ± 8.95 years. The mean preoperative central ACD was 2.95 ± 0.35 mm. At 10th and 30th POD mean central ACD were 3.94 ± 0.32, and 3.92 ± 0.28 mm respectively. Mean of increase in central ACD at final follow-up was 0.96 mm (p Conclusion: Phacoemulsification with posterior chamber in bag lens implantation can deepen the anterior chamber depth in patients with narrow angles. Based on these findings, it is concluded that phacoemulsification with foldable intraocular lens implantation is an effective tool in deepening the anterior chamber.

OTC-1型开顶式气室物理性能的测试与评价

针对OTC-1型开顶式气室的物理性能进行了评价,结果表明:在不同CO_2浓度下,CO_2送入量控制稳定,气室内CO_2浓度的水平和垂直分布均匀。在通风和不通风两种情况下,气室内温度和湿度分布基本相近,碳过滤器的过滤效率显著。

OTC-Ⅰ型开顶式气室优化设计与性能分析

为了模拟CO2、O3质量浓度升高的环境条件,OTC-Ⅰ型优化开顶式气室设计实现计算机自动控制气室内的气体质量浓度,其它环境条件接近自然状态,气室内空间适合木本植物生长。对气室性能试验分析结果表明,高质量浓度CO2处理(700μmol/mol)的变异量≤4%,高质量浓度O3处理(80mmol/mol)的变异量≤9%,说明处理气室内CO2与O3质量浓度比较稳定,各重复气室之间控制气体质量浓度无显著差异。本套系统可用于植物对气候变化的响应研究,所得数据相对可靠,是模拟气体环境的较好装置,适用于长期的监测研究。

自然通风条件下的两连接腔室中氢气泄漏试验研究

通过理论模型预测氢在自然通风条件的两连接腔室中缓慢泄漏而产生的氢-空气浮力射流。假设氢-空气混合物是线性混合类型,即密度仅是浓度的函数,通过三大守恒和伯努利方程得到并转化为非线性方程组,并进行了数值求解和试验验证。结果表明:两连接腔室中的一个腔室发生氢气泄漏时,连通口与泄漏区域区外侧通风口的相对位置对氢气分布的影响较大。增大中间连通口与泄漏区外侧通风口之间的距离和通风口面积都可以降低空间中的密度并提升高浓度出现的位置。分层高度与泄漏源高度呈正相关。本研究预测了氢气在自然通风的连通空间中的分散机制,从氢气风险控制的角度确定高浓度出现的位置,更好地为储氢设备的安全运行提供理论支持。

短期OTC处理对鹅绒委陵菜健康影响的研究初报

利用开顶箱(Open Top Chambers,OTC)模拟增温的方法,研究了短期变暖对鹅绒委陵菜健康的影响。结果表明,短期变暖后降低了鹅绒委陵菜的萌蘖株死亡数、增加了单位长度匍匐茎的萌蘖株数目和其死亡率,同时叶片数目、高度和健康率比对照增加,匍匐茎长度和匍匐茎上萌蘖株数目比对照减少,同时所有表征指标中只有萌蘖死亡率和叶片高度比对照有显著变化(p<0.05)。

光谱吸收型气体分析仪校准技术研究

光谱吸收型气体分析仪适合在开放场所应用,而可调谐半导体激光吸收光谱(TDLAS)气体分析仪具有不受粉尘、视窗、环境参数和背景气体交叉干扰,反应速度快和精度高等优点,近年来广泛地应用于恶劣工况的现场监测,但在线校准溯源技术的相关研究甚少。从TDLAS吸收光谱模型出发,分析了TDLAS分析仪测量原理和分类,提出采用标准浓度腔来校准TDLAS气体分析仪的方案。该方案提供了一种浓度均匀、量值稳定且背景单一的标准气体环境,成功对TDLAS分析仪进行了校准。经校准实例证明,方法可行,测量不确定度接近于标准气源的不确定度,最好可达1.1%。

550kV快速断路器液-机-气整机联合仿真

快速断路器可实现短路故障的快速切除,对保证电力系统安全稳定运行具有重要意义。针对一种快速响应、高速运动的新型液压操动机构,建立液压操动机构、传动系统和灭弧室之间的耦合关系,开展液-机-气联合仿真研究,分析不同操作功对动触头运动特性、液压缸缓冲特性和灭弧室反力特性的影响规律,在此基础上,对传动系统应力分布进行计算,对存在破坏风险的零部件提出改进策略,确定试验样机设计方案。研究结果表明:操作功对分闸速度影响明显,确定机构活塞杆侧作用面积为3160mm^(2),分闸速度提升至13.63m/s,触头机械分离时间缩短至4.45 ms,满足快速开断需求。随着机构操作功的提升,机构缓冲力峰值和灭弧室压气反力峰值提升明显,造成部分传动件应力值超标,通过优化液压操动机构缓冲性能以及传动件结构,设计出满足机械强度要求的传动系统。研究成果指导研发了操动机构试验样机,试验结果满足快速开断要求。

垄距和天气对玉米灌浆期开顶式气室(OTCs)增温效果的影响

气候变暖对作物生产系统影响显著,利用OTCs增温装置模拟农作物对气候变暖的响应是气候变化和农业生态领域的研究热点。作物生产系统在不同种植垄距下存在一定的水热交换差异,探明OTCs在不同垄距下的增温效果,尤其是在不同天气状况下的增温效果对分析作物生产系统响应气候变暖具有重要意义。本文在玉米灌浆期利用OTCs在黑龙江省海伦市野外田间开展了相同种植密度下垄距为55 cm、60 cm、65 cm和70 cm的模拟增温试验,利用Savitzky-Golay法和积分法定量分析了不同垄距,尤其是不同天气状况下,玉米OTCs冠层内外日温度变化特征和OTCs的增温幅度、增温时长和增温强度。研究发现,该装置能够使各垄距玉米冠层温度升高,65 cm垄距的增温时长最长,增温强度最大,升温最为明显。就增温幅度而言,55 cm垄距最大,65 cm垄距次之。不同天气状况下,晴天的增温幅度和增温强度最大,多云次之,雨天最小;但是,雨天天气下的增温时长最长。总之,不同垄距和天气状况显著影响OTCs装置的增温效果,垄距65 cm的增温效果最优,且晴天和多云天气下增温效果优于雨天。

富水砂卵石地层下衡盾泥带压开仓换刀技术及应用

研究基于沈阳地铁某区间盾构工程,深入探讨了衡盾泥带压开仓技术在富水砂卵石地层下的应用,旨在研究复杂地质条件下,盾构机更换专用刀具时采用的施工技术及其效果。通过数据分析方法,详细考察了泥膜稳定时间和开仓次数与建立泥膜次数的相关性。结果表明,随着建立泥膜次数的增加,阀开度的突变趋势愈发明显。基于此,提出了在建立泥膜后需密切关注阀开度的变化,并及时应对突变情况。此外,总结了在该地层条件下安全可控的开仓流程,显著提高了施工安全性和效率。研究成果可为未来类似复杂地层条件下的盾构施工提供了宝贵经验和实用指导。

Comparison of measurements of anterior chamber angle via anterior segment optical coherence tomography and ultrasound biomicroscopy

BACKGROUND Glaucoma is an irreversible optic neuropathy with the loss of visual field and decrease of vision.The variable clinical manifestations may result in differential diagnostic difficulties.The early screening and diagnosis of glaucoma are currently experiencing a demand for anterior segment analysis tools that can gather more information with one short measurement.Therefore,we analyzed the agreement,difference,and correlation of chamber angle parameters such as angel opening distance at 500μm(AOD500)and trabeculo-iris space area at 500μm^2(TISA500)measured by anterior segment optical coherence tomography(ASOCT)and ultrasound biomicroscopy(UBM).AIM To compare the differences,correlation,and agreement in measuring AOD500 and TISA500 by AS-OCT and UBM.METHODS Both AS-OCT and UBM were performed to measure AOD500 and TISA500 in 45 subjects(72 eyes).All subjects without glaucoma were collected from October 2015 to August 2016 at the Ophthalmology Department of the Fourth Affiliated Hospital of China Medical University.Data of the two groups(AOD500 and TISA500)were compared by nonparametric tests.Pearson correlative analysis and Bland-Altman analysis were used to compare the correlation and agreement.RESULTS There were no significant differences between AS-OCT and UBM in measuring AOD500(P1=0.110,P2=0.633,P3=0.078,and P4=0.474)and TISA500(P1=0.584,P2=0.889,P3=0.297,and P4=0.550)of the four quadrants of the anterior chamber angle.There was a high correlation in measuring AOD500(r1=0.562,r2=0.671,r3=0.635,and r4=0.720;P<0.001)and TISA500(r1=0.584,r2=0.889,r3=0.297,and r4=0.550;P<0.001).There was a good agreement in measuring AOD500 and TISA500 by the two modalities.CONCLUSION There is a high correlation and agreement between AOD500 and TISA500 measurements by AS-OCT and UBM.They are interchangeable under some circumstances.AS-OCT proves to be a better early screening tool for glaucoma.

开顶式气室的内外环境差异及其对小麦生长的影响

为探究开顶式气室(Open top chamber,OTC)内外环境差异及其对植物生长的影响,通过对比观测OTC内外的温度、湿度、光合有效辐射以及小麦的净光合速率、生物量、产量,评价了OTC对小麦生长的环境条件及叶片光合速率和产量的影响程度。结果表明:实验通气时间段(9:00—17:00),OTC内部温度比外部高4.8℃(P<0.05),相对湿度低0.6个百分点(P<0.05),光合有效辐射低32.3%(P<0.05)。OTC内小麦的净光合速率显著高于OTC外(P<0.05),且最大影响出现在小麦灌浆阶段。OTC内的小麦单株生物量增加了13.3%,其中穗生物量增加最多(35.2%);小麦单株产量增加了49.2%,其中籽粒数和千粒质量均增加了34.5%。实验结果不仅表明OTC增温能够促进农作物生产并提高产量,而且也提示,若采用OTC开展空气CO_(2)和O_(3)等浓度增加对植物影响模拟实验时,应该尽量减少OTC内外的微气候差异,并考虑OTC增温可能对实验结果的影响。

大气CO_(2)浓度缓增对冬小麦土壤呼吸的影响

为研究大气CO_(2)浓度缓增对冬小麦(Triticum aestivum)土壤呼吸的影响,基于开顶式气室组成的CO_(2)浓度自动调控平台,在2017—2019年开展了两季冬小麦CO_(2)浓度缓增试验.每季试验在背景大气CO_(2)浓度基础上(CK,对照),均设置了CO_(2)浓度缓增处理(C_(80)和C_(120),即从2016年起逐年增加40μmol·mol^(-1),至2017—2018年和2018—2019年冬小麦生长季CO_(2)浓度分别为CK+80μmol·mol^(-1)和CK+120μmol·mol^(-1)).采用静态暗箱-气相色谱法测定土壤呼吸速率.结果表明:CO_(2)浓度缓增没有显著改变土壤呼吸的季节变化规律,但是会显著影响冬小麦旺盛生长期的土壤呼吸速率.在2018—2019年冬小麦抽穗-扬花期,C_(120)处理使土壤呼吸速率显著增加50.2%(P=0.008),且使得生长季土壤碳排放显著增加25.9%(P=0.044),而在2017—2018年冬小麦生长季,与CK相比,C_(80)处理对土壤呼吸没有显著影响.土壤呼吸与土壤温度呈指数正相关,与CK相比,CO_(2)浓度缓增降低了土壤呼吸对温度的敏感性.研究表明,CO_(2)浓度缓增120μmol·mol^(-1)增加了冬小麦生长季土壤碳排放.

盾构气压开舱条件下的泥膜闭气失效理论研究

近年来,泥水盾构工法在越江跨海隧道中被广泛应用,在泥水盾构施工过程中,带压开舱始终是一个高风险、高难度技术环节。盾构带压开舱能否成功的关键在于泥膜的闭气性能。然而,一直以来泥膜闭气破坏机制、闭气时间及其影响因素从理论上较少探讨。对此,首先考虑了气体对泥膜中孔隙水的驱替作用,建立了泥膜压气从渗流启动-击穿渗透带的多相流模型,提出了泥膜压气渗水量和闭气时间评估方法;然后开展了室内渗透柱泥膜压气破坏试验,验证了所提出理论方法的适用性;最后探讨了气压、地层参数、泥膜厚度、泥浆剪切强度等参数对闭气时间的影响规律,揭示了盾构带压开舱以“泥皮为主、渗透带为辅”的闭气作用。研究成果对泥水盾构带压开舱的安全保障有一定的借鉴意义。

一种基于开放气室的土壤呼吸监测装置

针对传统开放气室需要将气体取样至红外气体分析仪(IRGA)测量CO_(2)浓度的不便,设计了一种土壤呼吸监测装置,并提出了补偿气体CO_(2)浓度不稳定时的修正计算方法。通过计算流体力学仿真分析,将一种小巧、轻便、低成本的非色散红外传感器模块布置于气室内部的合适位置,替代IRGA。控制气体流量为3、4、5 L·min^(-1),根据仿真软件获得土壤呼吸速率为0.5、2、5、10μmol·m^(-2)·s^(-1)时气室内的CO_(2)体积分数场。以气室底面中心点为原点建立笛卡尔坐标系,结合传感器模块尺寸分析,发现对于所述气室,由点(-0.0465,0.0717,0.2090)(单位为m)为球心、直径0.05 m确定的球形区域内,测量CO_(2)浓度计算土壤呼吸速率的平均误差不超过15%。将布置传感器后的装置与LI-8100开路式土壤碳通量测量系统,以及自制的密闭气室进行实地对比测验,平均误差为10.8%,与仿真分析结果一致。

深孔有压隧洞平板闸门小开度闸后水力特性及改善措施试验研究

深孔有压隧洞平板闸门小开度运行时,闸后水流侧收缩现象比较严重,流态较为复杂,需要采取一定的工程措施来改善闸后水流流态。基于物理模型试验与理论分析相结合的方法研究了不同导流坎坎高下的闸后水力特性。结果表明:闸后水流侧收缩现象随导流坎坎高的增加而减小,闸后水流水舌高度和水舌长度明显降低且底板负压基本消失,压强分布趋于均匀。但闸室导流坎坎高的增加对过流能力有一定影响,相对平底闸室,闸下过流能力随导流坎坎高的增加而减小,为避免影响过流能力,导流坎坎高不宜太大。

经皮失水测量技术

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