利用原位连续测定水汽δ^(18)O值和Keeling Plot方法区分麦田蒸散组分

利用稳定同位素技术和Keeling Plot方法可以有效分割地表蒸散量,进而加深对陆地生态系统水循环的理解。该研究通过原位连续测定麦田的水汽同位素数据,评价Keeling Plot方法在分割地表蒸散中的应用,并揭示华北冬小麦(Triticum aes-tivum)蒸腾在总蒸散中的比例。实验于2008年3-5月在中国科学院栾城农业生态站进行,利用国际上先进的H218O、HD16O激光痕量气体分析仪(TDLAS)为基础构建的大气水汽18O/16O和D/H同位素比原位连续观测系统,同时利用涡度相关技术、真空抽提技术、同位素质谱仪技术,获取了必要的数据。研究分析了一天中不同时间段的连续的大气水汽δ18O与水汽浓度倒数拟合Keeling Plot曲线的差异和可能的原因。结果显示,中午时段的拟合结果较好,这也暗示中午时段蒸腾速率高时最可能满足植物蒸腾的同位素稳定态假设。进一步的分析发现植物蒸腾的同位素稳定态并不总是成立,尤其是水分胁迫下进入成熟期的小麦,其蒸腾水汽同位素一般处于非稳定态。利用同位素分割结果显示,生长盛期麦田94%-99%的蒸散来源于植物蒸腾。

稳定性同位素技术与Keeling曲线法在陆地生态系统碳/水交换研究中的应用

稳定性同位素技术和Keeling曲线法是现代生态学研究的重要手段和方法之一。稳定性同位素能够整合生态系统复杂的生物学、生态学和生物地球化学过程在时间和空间尺度上对环境变化的响应。Keeling曲线法是以生物过程前后物质平衡理论为基础,将CO2或H2O的同位素组成(δD、δ13C或δ18O)与其对应浓度测量结合起来,将生态系统净碳通量区分为光合固定和呼吸释放通量,或将整个生态系统水分蒸散区分为植物蒸腾和土壤蒸发。在全球尺度上,稳定性同位素技术、Keeling曲线法与全球尺度陆地生态系统模型相结合,还可区分陆地生态系统和海洋生态系统对全球碳通量的贡献以及不同植被类型(C3或C4)在全球CO2同化量中所占的比例。然而,生态系统的异质性使得稳定性同位素技术和Keeling曲线法从冠层尺度外推到生态系统、区域或全球尺度时存在有一定程度的不确定性。此外,取样时间、地点的选取也会影响最终的研究结果。尽管如此,随着分析手段的不断精确和研究方法的日趋完善,稳定性同位素技术和Keeling曲线法与其它测量方法(如微气象法)的有机结合将成为未来陆地生态系统碳/水交换研究的重要手段和方法之一。

Research and Design of Drop Keel System for Multi-purpose Oceanographic Vessel

When an oceanographic vessel is sailing, the currents near the surface of ship hull are rapid, making it hard to meet the environmental requirements of scientific observation equipment. To guarantee the installation space and environmental requirements of the observation equipment, the drop keel system was proposed for the first time for ocean-graphic ships at China, to avoid the traditional ＂rudder-shaft＂ type fin keel＇s disadvantage. The research study will examine the operational mechanism and functions of the drop keel system, the operating conditions of the fin keel to determine the driver method and its arrangement, and the locking method of the fin keel underwater. The research wilI also provide some general designs for analyzing the best plan for the drop keel system.

Laboratory experimental study of water drag force exerted on ridge keel

With the diminishing Arctic sea ice,the dynamic energy-exchange process between sea ice and ocean gains in importance.Concerning how the ice bottom topography affects the drift of sea ice,it is unclear how the ridge keel-drag force exerted by seawater changes the momentum balance of sea ice.We thus conducted laboratory experiments to investigate how the local drag coefficient of the ridge keel depends on keel shape and on the relative velocity of ice with respect to seawater.A dimensional analysis is used to obtain the relationship between the local drag coefficient Cr,the Reynolds number Re,the dimensionless keel depth h0,and the keel slope angleφ.The results indicate that the local drag coefficient Cr is only relevant to Re when Re<4000 and the flow is in the laminar regime.With increasing Re,Cr depends on h0 andφ,which are independent variables,as the flow transitions to the turbulent regime.The parameterization formulas for Cr are also provided.

Internal solitary wave generation by the tidal flows beneath ice keel in the Arctic Ocean

A series of non-hydrostatic,non-linear numerical simulations were carried out to investigate the generation and evolution of internal solitary waves(ISWs)through the interaction of a barotropic tidal current with an ice keel in the Arctic Ocean.During the interaction process,the internal surge was generated at first,and then the wave gradually steepened due to non-linearity during its propagation away from the ice keel.The internal surge eventually disintegrated into multi-modal and rank-ordered ISW packets with the largest having an amplitude of O(10)m.Sensitivity experiments demonstrated that the ISWs’amplitudes and energy were proportional to the varying ice keel depths and barotropic tidal fl ow amplitudes,but were insensitive to the changing ice keel widths.Typical ISWs can enhance the turbulent dissipation rate of O(10^(-6))W/kg along their propagation path.Further,heat entrainment induced by the wave-ice interaction can reach O(10)MJ/m per tidal cycle.This study reveals a particular ISW generation mechanism and process in the polar ice environment,which could be important in impacting the energy transfer and heat balance in the Arctic Ocean.

The keele curriculum model: A contemporary framework for designing an inter-professional technology enhanced nursing curriculum

This paper outlines a curriculum model for contemporary programme design for the purpose of embedding educational innovation and technology within an inter-professional nursing curriculum. It has been developed from work within the School of Nursing and Midwifery at Keele University during the re-write of both the nursing and midwifery curriculum. The Nursing and Midwifery Council (NMC) require approval of all recordable programmes every five years and as such the school took this review as an opportunity to explore the curriculum model currently in use and develop an approach that would facilitate the professional requirements of the programme alongside the embedding of innovative learning and teaching methodologies. The model springs from extensive application of contemporary pedagogy underpinning adult learning, and forces consideration of cognitive alignment within a multi-modal delivery framework [1]. The model builds upon the early work of Fowler and Mayes [2] and later work of Bird [3] who explored the antecedents and underpinning theory for success within online learning experiences. This model has greater reach;having strategic fit for acontemporary “technology enhanced learning” application within further and higher education [4], whilst ensuring the achievement of given professional standards [5].

Wear Resistance Improvement of Keeled Structure and Overlapped Distribution of Snake Scales

The movement mode of snakes is crawling,and the living environment of snakes with numerous branches and stones will cause plenty of wear for the snake scales.There are plenty of surface structures and morphology on snake scales to avoid severe wear.Among them,the research towards the keeled structure on snake scales is missing.Therefore,in this research,the wear resistance improvement of the keeled structure on the snake scales and the overlapped distribution of snake scales are investigated.The keeled and smooth snake scales were 3D printed and they were distributed on the substrate in the overlapped or paralleled ways.Besides these four samples with keeled/smooth scales and overlapped/paralleled distributed,there is also a reference sample with the same thickness.Based on the tribology test,the number of grooves of samples with the keeled structures is higher than that of samples with smooth surfaces,which indicates that the keeled structure dramatically enhances the wear resistance of snake scales,especially during the wear in the vertical direction.The experiment on surface morphology greatly compromised the result of the tribology test.In addition,the bottom portion of the keeled snake scales can be protected by the keeled structure.Besides,the overlapped distribution can protect the central region of snake scales and provide double-layer protection of the snake body.Overall,the keeled structure and the overlapped distribution play a significant part in the improvement of wear resistance of the snake skin.These findings can enhance the knowledge of the reptiles-mimic surface structure and facilitate the application of military uniforms under high-wear conditions.

装配式轻钢框架-轻钢骨架轻混凝土墙板结构抗震性能

为研究装配式轻钢框架-轻钢骨架轻混凝土墙板结构抗震性能,对1个足尺轻钢框架结构试件和3个足尺轻钢框架-轻钢骨架轻混凝土墙板结构试件进行了低周反复荷载下的抗震性能试验及理论分析,试件变量包括:2种装配构造,即内嵌式装配墙板、外贴式装配墙板;2种轻钢骨架轻混凝土墙板,即框架式轻钢骨架轻混凝土墙板、桁架式轻钢骨架轻混凝土墙板。研究了各试件的破坏特征和损伤演化过程,分析了结构滞回特性、承载力、变形能力、刚度退化、耗能性能和应变。结果表明:装配式轻钢框架-轻钢骨架轻混凝土墙板结构共同工作性能良好,其水平承载力相比轻钢框架提高了204.7%~210.4%,抗侧刚度提高了257.3%~512.5%,结构变形及耗能能力有显著提高;内嵌墙板的自攻钉连接构造以及外贴墙板的螺栓连接构造传力性能可靠,结构具备2道抗震防线的受力特征;基于简化塑性分析模型以及拉压杆软化桁架模型,对试件承载力进行了计算,计算结果与试验符合较好。

轻钢龙骨防火组合楼板梁板节点连接试验研究

轻钢龙骨防火组合楼板是一种新型的装配式楼板,因为自重较小,同时具有较大的承载力,板底板顶附层为防火楼板,具有较好的防火能力,该种楼板作为简支板直接放置于工字钢梁上,支座处无法传递负弯矩,因此在梁顶支座处会出现一条通缝,严重影响使用效果,同时简支板体系也不符合抗震规范的要求。本文提出一种新的支座处梁板节点连接方式,目的是通过合理连接,实现支座处能够传递负弯矩,由简支变为固结。试验采用液压千斤顶对试件施加静荷载,对11个全比例节点连接试件进行研究,考虑连接件搭接长度、连接件厚度、连接所用的自攻螺钉(螺栓)的数量,以及连接件尺寸对梁板连接节点承载力和挠度的影响,并对节点连接件与C型轻钢龙骨之间的变形协调能力做出了分析。研究表明,本文提出的以Z型钢为连接件的梁板节点连接方法安全可靠,可实现该新型楼板的双跨以及多跨连接。

轻钢龙骨复合墙板研究进展

装配式钢结构建筑具有抗震性能好、自重轻、施工速度快等优点,但因与其配套的围护外墙板较少,制约了装配式钢结构的发展。近年来结构轻便、保温性能好、抗震性能优良的轻钢龙骨复合墙板被逐渐应用到装配式钢结构建筑当中。对现有轻钢龙骨复合墙板进行了分类,总结了各类墙板的特点,并介绍了国内外针对墙板的抗弯性能、抗剪性能、抗震性能以及热工性能等方面的研究现状。在此基础上,分析了轻钢龙骨复合墙板存在的问题,提出了一种热工与防火性能好、自重轻、连接安全可靠、管线易于分离且可工业化生产的新型轻钢龙骨复合墙板。

轻钢龙骨复合保温外墙板抗弯性能研究

为了研究轻钢龙骨复合保温外墙板的抗弯性能,采用有限元分析软件ABAQUS对墙板进行了模拟分析,并与已有研究进行对比。研究了轻钢龙骨和覆面板等参数对墙板抗弯性能的影响,并对比了风荷载下墙板的正常使用情况。基于装配式钢结构建筑对外墙板的性能要求,提出了一种由轻钢龙骨、覆面板、保温层和防护层组成的轻钢龙骨复合保温外墙板。研究表明:该墙板的整体受力性能较好,其中增加轻钢龙骨腹板高度对墙板影响最显著,与龙骨腹板高度为100 mm时相比,高度为120、150、180 mm时墙板屈服荷载提高了39.31%、71.92%和101.3%,极限荷载提高了42.48%、72.9%、104.53%,有无龙骨加强肋几乎不影响墙板的抗弯性能。

方钢龙骨模板体系施工技术在剧院建筑中的应用

混凝土完成面的垂直度、平整度及美观度关系混凝土结构质量验收。高大空间墙、柱、梁板模板整体刚度的控制难度较大,传统木龙骨在运输过程中时常发生变形翘曲,模板穿孔后产生的各种损耗更是不可估量。在“双碳”目标背景下,方钢龙骨模板体系施工技术利用方钢龙骨刚度大、环境适应能力强及材料均质性等特点,实现了“以钢代木,以整代拼”,优化革新了传统混凝土模板体系施工,经济社会效益较好。

龙骨骨折对产蛋后期蛋鸡恐惧行为、生产性能和蛋品质的影响

【目的】龙骨骨折(keel bone fracture, KBF)已成为影响蛋鸡健康和生产的重要福利问题。试验旨在评估产蛋期龙骨骨折的发生与否对产蛋后期的蛋鸡恐惧行为、生产性能和蛋品质的影响。【方法】选取60周龄的海兰褐蛋鸡和林甸鸡各100只,单笼饲养于传统叠层式鸡笼。利用触诊和便携式X光仪区分龙骨骨折蛋鸡和未骨折蛋鸡,通过紧张不动性测试(TI)、旷场试验(OFT)和惊吓反射试验(SRT)依次测量恐惧行为反应,并测定68周龄时蛋鸡的生产性能和蛋品质。【结果】在TI试验中,2个品种龙骨骨折蛋鸡的紧张不动时长显著高于正常蛋鸡(P<0.05)。在OFT试验中,龙骨骨折的海兰褐蛋鸡和林甸鸡在穿过的格子数、步数和在外圈停留的时间均显著低于正常蛋鸡(P<0.05),在内圈停留的时间显著高于正常蛋鸡(P<0.05),且骨折的海兰褐蛋鸡的运动潜伏期显著高于正常蛋鸡(P<0.05)。在SRT试验中,龙骨骨折蛋鸡惊吓反射总得分显著低于正常蛋鸡(P<0.05)。因此,龙骨骨折蛋鸡的恐惧行为反应较强烈。2个品种龙骨骨折蛋鸡的产蛋率显著低于正常蛋鸡(P<0.05),且骨折的海兰褐蛋鸡蛋形指数低于正常蛋鸡(P<0.05),其余蛋品质参数在骨折蛋鸡和正常蛋鸡中无显著性差异(P>0.05)。【结论】龙骨骨折加剧了蛋鸡的恐惧行为反应,降低了产蛋后期蛋鸡的福利水平和生产性能。

Prevention of laryngeal webs through endoscopic keel placement for bilateral vocal cord lesions

Transoral microresection for treatment of vocal cord lesions involving the anterior commissure may result in anterior glottic webs. In this study, we retrospectively reviewed 54 patients who underwent microsurgery for bilateral lesions involving the anterior commissure and categorized them into two groups. The keel placement and control groups received endoscopic keel placement and mitomycin C, respectively. During the follow-up of at least 1 year, the laryngeal web formation rate significantly decreased in the keel placement group compared with that in the control group （18.6% versus 54.5%, P 〈 0.05）. Furthermore, the voice handicap index-10 scores for patients without web formation decreased in both the keel placement and control groups （P 〈 0.0001 and P 〈 0.001, respectively）. A pseudomembrane covering the vocal cords was detected in 16.3% （7 of 43） cases after keel removal. A total of 100% （7 of 7） of these cases and 2.8% （1 of 36） of the other cases formed laryngeal webs （P 〈 0.0001）. Endoscopic keel placement could be an effective method for preventing anterior glottic webs after surgery for bilateral vocal cord diseases involving the anterior commissure. The pseudomembrane observed at the time of keel removal may imply a high risk of web formation.

柴胡加龙骨牡蛎汤加减治疗肝郁化火型失眠的效果观察及有效率分析

目的:观察肝郁化火型失眠采用柴胡加龙骨牡蛎汤加减治疗的临床效果,同时分析该治疗方式的有效率。方法:选取2020年7月至2022年7月福建省安溪县湖上卫生院收治的肝郁化火型失眠症患者76例作为研究对象,按照单双号法分成对照组和观察组,每组38例。对照组治疗方式为口服舒乐安定,观察组治疗方式为柴胡加龙骨牡蛎汤加减,对2组患者临床效果、睡眠质量、心理状况、药物不良反应、生命质量等进行比较。结果:观察组治疗总有效率明显高于对照组,差异有统计学意义(P<0.05);2组治疗前SAS评分、SDS评分进行比较,差异无统计学意义(P>0.05);治疗后,观察组SAS评分、SDS评分优于对照组,差异有统计学意义(P<0.05);观察组睡眠时间、日间功能、睡眠效率、入睡时间等睡眠质量评分优于对照组,观察组不良反应发生率低于对照组,差异有统计学意义(P<0.05);观察组附加关注、社会、功能、生理、情感等生命质量评分与总分明显高于对照组,差异有统计学意义(P<0.05)。结论:柴胡加龙骨牡蛎汤加减治疗方式对肝郁化火型失眠患者睡眠质量、生命质量、心理状况的改善具有良好的促进作用,且整体治疗效果确切,安全性高,值得临床推广。

新型轻钢龙骨复合墙体热、湿性能研究

为了精准预测轻钢龙骨复合墙体内部温湿度分布规律,解决当前建筑维护结构保温防湿性能研究不足的问题,提出了通过数值模拟的方法对复合墙体内部温湿性能进行分析研究。基于多孔介质传热传质理论,以轻钢龙骨复合墙体为研究对象,采用轻钢龙骨复合墙体三维瞬态的热湿耦合数学模型进行研究。对比分析不同腹板开孔长度和构造形式以及加入隔汽层对复合墙体内部热湿性能的影响,得出复合墙体内部的热湿耦合瞬态变化规律。实验结果表明:腹板开孔轻钢龙骨的存在对复合墙体内部的温湿度变化规律具有显著影响,开孔不同则材料内部的温湿度变化也不相同;在轻钢龙骨复合墙体中不同内夹层在性能上存在着明显的差异,聚苯乙烯泡沫(EPS)的保温吸湿效果优于泡沫混凝土;从防止发生冷凝的角度考虑,在加入隔汽层后,泡沫混凝土的保温和防湿性能皆有所提高,这说明在墙体内部加入防湿层可有利于防止发生冷凝现象。

吊顶用轻钢龙骨及配件国内外检测标准比较与分析

通过对吊顶用轻钢龙骨及配件相关的国内外标准进行研读和讨论,并对基材、外观质量、尺寸公差、耐腐蚀性能、力学性能技术要求及试验方法进行对比,分析不同国家标准的差异性,为龙骨产品在国际贸易及合作中的发展提供参考,同时也为国标的修订提出改进力学性能、防腐蚀性能技术要求等合理化建议。

轻钢龙骨复合外墙热工性能模拟与实测对比研究

轻钢龙骨复合外墙由于热桥及多层非均质结构的影响,其传热机理复杂,特别是含空气间层的墙体存在导热、对流、辐射三种热传递方式的耦合效应,其热工性能难以采用传统计算方法进行精确求解。利用有限元软件COMSOL,从基本传热原理出发,对4种不同构造组成的轻钢龙骨复合外墙的热工性能进行多场耦合模拟,并采用防护热箱法对模拟值进行实测验证分析。结果表明:有限元软件COMSOL可以准确可靠地模拟分析出此类复合墙体的热工性能,其模拟值与测试值(偏差在2%以内)具有较高的吻合度;在空气间层内完全填充岩棉类保温材料比50 mm空气间层的保温性能好;粘贴聚乙烯隔热胶带等断热材料可有效改善轻钢龙骨处的热桥效应。

多功能金属龙骨力学性能检测装置的研制

金属龙骨按材质、使用场合、断面形状分类众多,不同类型龙骨的力学性能检测方法不一,检测装置各异。本文通过对国内外金属龙骨标准的力学性能检测方法进行分析,研制出一种符合多标准、多类型的多功能金属龙骨力学性能检测装置,并分析其可行性和操作特点。

ZG230-450铸钢基尔试块断后伸长率不合格原因

某熔炼炉浇注的ZG230-450铸钢基尔试块在正火后的拉伸试验过程中,其断后伸长率不合格。采用宏观观察、化学成分分析、扫描电镜与能谱分析、金相检验等方法对其断后伸长率不合格原因进行分析。结果表明:拉伸试样中存在沿初生奥氏体晶界析出的点状MnS夹杂物,弱化了晶界结合力,在拉伸载荷的作用下,裂纹沿初生奥氏体晶界扩展,形成穿晶韧窝+沿晶韧窝混合型石状断口,造成材料的断后伸长率不合格。