关于冻冰融冰度日法推算渤海冰厚的商榷

结合近几十年来渤海沿岸海洋站的实测冰厚资料，利用冻冰融冰度日法对无冰厚有气温资料年份的海冰厚度进行了推算。通过进一步的分析论证，发现该方法在渤海海冰适用性方面还存在几点需说明的问题，即渤海海冰的特殊性局限了它的应用范围。本文介绍对这些问题的一点初浅认识，供有关人员进一步商榷。

有限厚度冻冰相变过程的传热研究

For a finite dimensional slab of cold energy storage, the ice freezing process inside itat different freezing temperatures were theoretically investigated by adopting a combinationmethod of analytical and integral solutions. Through this study, the formulas predicting thetimely variation of ice-water interface position, the transient heat flux on the slab boundaryand the amount of clod energy stored into the slab during a freezing period were obtained-Meanwhile, the influences of freezing temperature and thickness of ice on the phase-changerate, heat fiux and charging time of the slab were also discussed in detail.

自密实沙漠砂贫混凝土饱水冰冻后的力学及耗散能特征研究

为了研究自密实沙漠砂贫混凝土饱水冰冻后的力学性能,开展了饱水后的低温冰冻试验,并与干燥状态和饱水状态下的试验结果进行了对比,结果表明:(1)单轴抗压强度较干燥时提升了2.6~5.2倍,较饱水时提升了3.8~8.9倍,弹性模量较干燥时提升了1.2~1.8倍,较饱水时提升了1.7~1.9倍,强度的提升幅度要大于弹性模量的提升幅度,延性系数及耗能系数都略有提高;(2)随着水泥掺入量的增大,强度逐渐增大,但是峰值应变逐渐减小,说明强度在提高的同时其脆性也在增强,延性在下降,与相同配合比的干燥试块和饱水试块相比,饱水冰冻试块的峰值应变较大,说明在低温下其延性有所提高;(3)饱水冰冻后强度和刚度提升的内在机理是冰贡献了一部分强度和刚度,可能是微孔隙中的水结冰后成为了试块的一部分,相当于提高了混凝土的密实度,并且水冻结后提高了骨料颗粒间的黏聚力和咬合力。

西南低压对冰(霜)冻天气过程的影响

2004年末2005年初,由于受强冷空气的影响,共计有68站次出现了零度以下的日最低气温,和1991年12月28-29日的大范围冰(霜)冻天气的过程环流特征演变及气象要素分析作对比分析,发现这两次过程均有欧亚大陆两槽一脊控制,高空盛行很强的经向环流,西北气流旺盛,冷平流明显,850 hPa温度低,850百帕和地面冷高压强度强,地面气温低、湿度干,露点低等特点。但由于受到西南低压云系东移的影响,700hPa和850 hPa广西的湿度都较大,云容易长起来,同时水汽本身就是一种温室气体,减少了辐射降温,所以虽然最低气温很低,但达到霜冻的站数都在40个站左右,持续时间不长。

考虑冰盖生消和冰-结构-冻土协同作用的渠道弹性地基梁模型

冰-冻破坏是寒区冬季输水渠道结构破坏的主要原因,而目前尚缺乏准确的分析方法和评价准则。本文从冰盖生消过程中结冰初期、流冰期和封冻期3个阶段衬砌结构冰冻破坏机理出发,考虑在冰-结构-冻土协同作用下,基于弹性地基梁Winkler理论推导了衬砌结构的挠曲线微分方程,分别建立了3个阶段衬砌结构的冰冻破坏力学模型,并结合相应荷载组合和边界条件对模型求解获得了衬砌结构的挠度、内力和应力的解析表达。应用该模型对南水北调京石段某输水渠道进行冰冻破坏分析计算,结果表明:结冰初期、流冰期和封冻期3个阶段衬砌结构的法向冻胀位移最大值分别为10.62、13.89和5.05 cm,对应3个阶段衬砌结构的截面最大拉应力分别为3.63、4.11和2.05 MPa,且破坏位置均在冻结区坡板的中下部,与现场监测渠道冰冻破坏分布规律吻合。据此,建议寒区冬季输水渠道控制运用中应尽量缩短结冰初期、流冰期时间,延长第3阶段稳定封冻期时间,同时应合理控制地下水位和冰盖厚度。研究结果可为寒区冬季输水渠道抗冰冻设计提供理论依据和分析方法。

细砂EPS混凝土的软化特征与饱水冰冻后的力学性能研究

为了研究细砂EPS混凝土在有水和低温环境下的力学性能,对其开展了饱水和饱水冰冻环境下的单轴压缩试验,并与干燥状态下的试验结果进行了对比,结果表明:饱水后的割线模量变小,延性增强,强度下降了约25%;饱水冰冻后对割线模量的影响不大,但脆性得到增强,且强度增大了约38%。

干湿复合橡胶粉改性沥青混合料性能及抑冻破冰试验研究

以干法改性工艺将橡胶粉颗粒掺入稳定型橡胶粉改性沥青混合料中,研究了橡胶粉颗粒掺量对稳定型胶粉改性沥青混合料性能及沥青路面抑冻破冰效果的影响。结果表明:随着橡胶粉颗粒掺量增加,改性沥青混合料的路用性能与抗疲劳性能呈先提高后降低,当橡胶粉颗粒掺量为3%时,干湿复合橡胶粉改性沥青混合料具有优良的高稳定性、低温抗裂性、水稳定性和抗疲劳性能;掺入橡胶粉颗粒能够快速恢复稳定型橡胶粉改性沥青路面在凝冰条件下的抗滑性能,抑冻破冰效果随橡胶粉颗粒掺量增加而增大;综合路用性能和抑冻破冰效果,橡胶粉颗粒的最佳掺量为3%。

2021-2022年冬季辽东湾海冰冰情动态和模拟研究

每年冬季辽东湾水域的海冰给当地的社会、经济带来重大影响,各个行业部门也非常关注海冰的发展,并希望能够对冰情的发展作出合理的预测。研究针对2021-2022年冬季辽东湾,根据观测数据建立了海冰面积、冰缘线离岸距离和三日平均气温、积温、累积冻/融冰度日的时间序列,分析冰情和温度参量之间的关系;分别针对海冰发展期和融冰期,建立冰情与候气温、积温、累积冻冰度日和累积融冰度日的函数关系,结果表明,发展期,积温和累积冰冻度日能够较好地拟合冰情变化;融冰期,候气温能够较好地拟合冰情变化。研究成果对于未来渤海水域冰情模拟预测提供了一个很好的参考;同时,研究关于冰缘线离岸距离的分析和模拟,对于冬季渤海水域的船舶航行安全具有重要意义。

超疏水和RTV涂层表面覆冰剪切强度及其影响因素的对比分析

超疏水涂层和RTV涂层都具有防冰性能,但关于两者防冰性能的对比研究较少。文中使用覆冰剪切强度降低系数λ对比两种涂层防冰性能的差异,并通过理论模型计算了λ的理论值。在低温试验箱内对涂敷了两种涂层的4种材质基板进行覆冰剪切力实验,并在实验中设置了不同的冻冰时间、覆冰环境温度。实验结果表明,RTV涂层表面覆冰剪切强度是超疏水涂层的13~86倍,覆冰剪切强度降低系数λ理论值和实验值相符合;随冻冰时间的延长,覆冰剪切强度逐渐增大或基本不变;随覆冰环境温度的降低,覆冰剪切强度呈先增大后减小再增大的趋势;不同基板材质表面的覆冰剪切强度均是超疏水绝缘涂层小于RTV涂层。冻冰时间和覆冰环境温度对两种涂层表面覆冰剪切强度的影响规律并不完全相同。

路基冻结过程中温度场对变形场的影响

为了研究冻土路基温度场及变形场的动态变化规律,基于伴有相变的路基非稳态温度场控制方程和冻土路基变形场二维数值计算模型,对冬季冻土路基温度场和变形场进行了计算分析,得出路基深层土中的温度变化滞后于表层土和气温;对于冻胀冰锋线分布较广的路基,其破坏易在坡脚处产生;冻胀冰锋线分布范围较小的路基,破坏大致发生在竖向位移较大的路基中部。结果表明,冻胀冰锋线的范围是影响路基变形场的重要因素。

考虑冰荷载概率模型的重力式桥墩破坏分析

冰凌对桥梁下部结构的影响不可忽视,但我国规范中对冰荷载的规定尚不完善,未考虑流冰的惯性作用和冰排尺寸对冰撞力的影响。结合冻冰度日法建立冰厚计算公式,并引入冰速、地区系数等影响系数,推导出适用于不同地区、不同桥梁下部结构形式的冰压力计算公式。通过假设冰凌期冻冰度日的概率分布满足正态分布,流速和冰盖面积满足Gamma分布,建立冰荷载概率模型。对重力式桥墩受力形式进行简化,提出考虑桥墩抗滑移性能、抗倾覆性能、最不利截面强度的桥墩破坏模型。最后结合算例,利用蒙特卡洛法得到重力式桥墩失效概率与冰排尺寸的关系曲线,验证坍塌事故过程。

北京金海湖戏水宫工程结构设计分析

就北京金海湖戏水宫工程结构设计中所遇到的计算程序的应用及冻冰荷载对结构的影响等问题 ,结合工程实践进行相应的分析比较 ,提出简化计算的方法 。

Environmental Stresses and Redox Status of Ascorbate

To investigate the effects of environmental stresses on ascorbic acid content and its redox status, the effects of freezing and drought on ascorbate and dehydro-ascorbate content and activities of four enzymes involved in the ascorbate-glutathione cycle in some conifers were studied. The results showed that both freezing and drought induced the decrease in ascorbate content and the increase in dehydro-ascorbate content. The activities of ascorbate peroxidase (APX) and monodehydro-ascorbate reductase (MDAR) were decreased by freezing stress. At the beginning of exposure to air, water loss from detached needles induced the increase in the activities of APX and MDAR. Further water loss turned to decrease the APX and MDAR activities. The activities of dehydro-ascorbate reductase (DHAR) and glutathione reductase (GR) were not sensitive to changes in temperature and water content of the needles. It is concluded that moderate temperature or water stresses may induce the acclimation and increase in the ability of the H2O2 scavenging system, while strong stresses decrease the ability and induce injury of plant tissues. Correlation between ascorbate content and activities of related enzymes and cold tolerance of conifers were also reported.

Relationships between Froze Damaged and Tree-measuring Factors of Huodendron biaristatum Species in Damingshan

[Objective] The aim was to provide a reference for studying the resistant ability of subtropical forest to freeze disaster and detecting the recovery and evolution of Huodendron biaristatum species after freeze disaster.[Method] Effects of the damage caused by the southern ice storm in early 2008 on Huodendron biaristatum,dominant species of evergreen broad-leaved forest on the Damingshan,were studied in the aspect of population ecology.[Result] Among the 1 090 Huodendron biaristatum individuals （DBH ≥ 1 cm）,697 individuals were victims,accounting for 63.9%.The largest part of the victims was crown breakdown,which took up 37.6%.13.0% of the victims were bent,and 10.2% of the victims were trunk broken.The least part of the victims were uprooted,accounting for only 3.1%.Different types and extent of forestry damage had remarkable differences in diameter class,tree height,crown and taper.Rates of damage and crown breakdown increased with the increase of DBH,while bent rate decreased.Rates of damage,bent and trunk broken declined slowly with the increase of tree height,while crown breakdown rate followed the normal distribution.As the crown level increased,rates of damage and crown breakdown increased,while the rate of trunk broken decreased.Individuals with high taper were more susceptible to crown damage,bending,breaking and uprooted.[Conclusion] The resistant ability of Huodendron biaristatum species to freeze disaster is affected by many factors like DBH,tree height,crown,taper,etc..Huodendron biaristatum species in Damingshan affected by those factors show various kinds of damaged types dominant by mechanical damage,but there is few individual to die.

Effects of Freezing Disaster on Green-up Date of Vegetation Using MODIS/EVI Time Series Data

In the field of global changes, the relationship between plant phenology and climate, which reflects the response of terrestrial ecosystem to global climate change, has become a key subject that is highly concerned. Using the moderate-resolution imaging spectroradiometer (MODIS)/enhanced vegetation index(EVI) collected every eight days during January- July from 2005 to 2008 and the corresponding remote sensing data as experimental materials, we constructed cloud-free images via the Harmonic analysis of time series (HANTS). The cloud-free images were then treated by dynamic threshold method for obtaining the vegetation phenology in green up period and its distribution pattern. And the distribution pattern between freezing disaster year and normal year were comparatively analyzed for revealing the effect of freezing disaster on vegetation phenology in experimental plot. The result showed that the treated EVI data performed well in monitoring the effect of freezing disaster on vegetation phenology, accurately reflecting the regions suffered from freezing disaster. This result suggests that processing of remote sensing data using HANTS method could well monitor the ecological characteristics of vegetation.

Clinical Diagnosis Technique of Goat Pox Disease

[Objective] The aim was to provide theoretical basis for effective prevention of goat pox disease.[Method] 5 cases of infected goats were diagnosed for goat pox with microbiology examination.The poxes on their skin,rumen,reticulum,omasum,abomasum and submandibular lymph nodes,bronchial lymph nodes,lung and spleen were macroscopically and microscopically observed with pathanatomical and histopathological technique.[Result] Poxes on skin mainly showed ashen hemisphere state and gave prominence to the surface of skin; some cases had hemorrhage in the poxes and showed dark purplish red.Poxes on gastric mucosa showed ashen.Cytoplasmic inclusion body could be all observed in epithelial cells of the poxes and macrphages of lymph node,lung and spleen.[Conclusion] Poxes on skin,lung and the surface of gastric mucosa as well as cytoplasmic inclusion body in the epithelial cells of pox and the macrphages of lymphoid organs were the especial pathochanges of goat pox,which could be taken as the proof of goat pox＇s clinic diagnisis.

INFLUENCE OF AIRCRAFT DEICER ON FREEZE-THAW DURABILITY OF HIGH PERFORMANCE CONCRETE

The influence of glycol,the main composition of the most frequently used aircraft dicer,on the freeze-thaw durability of high performance concrete（HPC）is investigated.Freeze-thaw durability of HPC is tested by accelerated freeze-thaw test.Four kinds of the solution,i.e.,tap water,3.5% NaCl solution,glycol solutions,and a LBR-A type commercial aircraft deicer are employed.Results show that freeze-thaw durability of HPC exposed to glycol solutions is closely related to the solution concentrations.The failure of HPC exposed to 3.5% glycol solution is similar to that of those exposed to 3.5% NaCl solution,i.e.,serious surface scaling.While the damage of HPC exposed to 12.5%—25% glycol solutions is postponed.Compared with glycol solution,the commercial aircraft deicer has much more negative effects on HPC freeze-thaw durability compared with 3.5% NaCl solution.In the presence of commercial aircraft deicer for HPC subjected to freeze-thaw cycles,the deterioration is mainly due to scaling and spalling.

Effects of Short-term Freezing on Endodormancy Release in Nectarine Bud

[Objective] This study aimed to investigate the endodormancy release in nectarine bud treated by short-term freezing. [Method] Through short-term freezing at seven different temperatures for three different periods on bud, the livability, burst, ratio of free water to bound water and membrane permeability of ＇Shuguang＇ nec- tarine bud were studied. [Result] On November 10, compared with non-freezing treatment （CK）, the bud burst, ratio of free water to bound water and membrane permeability treated by freezing at -5 and -8 ℃ were almost the same as CK. But the rest freezing treatments advanced the date of endodormancy release, while the bud burst, ratio of free water to bound water and membrane permeability were high- er than CK. on November 20 and 30, the effects of the freezing treatment on en- dodormancy release were the same when the treatment on November 10, and the effect was better as the treatment was later. [Conclusion] The correlation of the rate of bud burst, ratio of free water to bound water, and membrane permeability of the different freezing treatments indicated that the change from bound water to free wa- ter and the increase of membrane permeability were probably the signal of endodor- mancy release.

Ice melting performance of deicers and their effect on stripping resistance of asphalt mixture

The ice melting performance of three types of deicers, including sodium chloride, calcium chloride and sodium acetate, were tested in laboratory under different temperature conditions, and their effects on asphalt mixture were evaluated from the point of the stripping resistance of asphalt mixture. Unsaturated Marshall samples were exposed to freeze-thaw cycling while immersed in the deicer solutions of different concentrations. After the freeze-thaw cycles, Cantabro tests were performed, and Cantabro loss was adopted to characterize the stripping resistance of asphalt mixture. The test results show that calcium chloride has the best comprehensive ice melting performance, and all deicers have detrimental effect on the stripping resistance of asphalt mixture at different degrees. The damage degree depends on deicer types and their concentration in the solution. Deicer solutions with about 2% concentration cause the greatest loss of stripping resistance due to serious freeze-thaw damage. Sodium acetate causes greater loss of stripping resistance than sodium chloride and calcium chloride at the same concentration.