Spatial pattern recognition for near-surface high temperature increases in mountain areas using MODIS and SRTM DEM

Abrupt near-surface temperature changes in mountainous areas are a special component of the mountain climate system.Fast and accurate measurements of the locations,intensity,and width of the near-surface changes are necessary but highly difficult due to the complicated environmental conditions and instrumental issues.This paper develops a spatial pattern recognition method to measure the near-surface high temperature increase(NSHTI),one of the lesser-attended changes.First,raster window measurement was proposed to calculate the temperature lapse rate using MODIS land surface temperature and SRTM DEM data.It fully considers the terrain heights of two neighboring cells on opposite or adjacent slopes with a moving window of 3×3 cell size.Second,a threshold selection was performed to identify the NSHTI cells using a threshold of-0.65℃/100 m.Then,the NSHTI strips were parameterized through raster vectorization and spatial analysis.Taking Yunnan,a mountainous province in southwestern China,as the study area,the results indicate that the NSHTI cells concentrate in a strip-like pattern along the mountains and valleys,and the strips are almost parallel to the altitude contours with a slight northward uplift.Also,they are located mostly at a 3/5 height of high mountains or within 400 m from the valley floors,where the controlling topographic index is the altitude of the terrain trend surface but not the absolute elevation and the topographic uplift height and cutting depth.Additionally,the NSHTI intensity varies with the geographic locations and the proportions increase with an exponential trend,and the horizontal width has a mean of about 1000 m and a maximum of over 5000 m.The result demonstrates that the proposed method can effectively recognize NSHTI boundaries over mountains,providing support for the modeling of weather and climate systems and the development of mountain resources.

Distribution Characteristics of High Temperature Damage and Its Influence on the Rice Yield in the Area along Huaihe River

[Objective] The research aimed to study the distribution characteristics of high temperature damage and its influence on the rice yield in the area along Huaihe River.[Method] The meteorological data of 10 stations in the area along Huaihe River during 1965-2009 and the yield data of Anhui single-season middle rice during 1967-2006 were selected.The occurrence characteristic of summer high temperature weather and the intensity of high temperature damage in the area along Huaihe River were analyzed.Based on the previous high temperature damage index of rice,Changfeng County where was the typical rice planting zone in the area along Huaihe River was as the representation,and the yield damage loss rate risk of high temperature damage in Changfeng was analyzed by combining with the historical yield data.[Result] The high temperature weather in the area along Huaihe River frequently happened.The high temperature damage presented 'N' shape trend from west to east.The occurrence frequency of high temperature weather in Huainan and Bengbu where were in the middle area along Huaihe River was more and was less in Huoqiu and Shouxian where were near the south mountain area of Anhui.The occurrence time mainly focused from the middle and last dekads of July to the first dekad of August after the plum rain.At this time,it was the booting,heading and flowering periods of single-season middle rice,and the influence on the rice yield was obvious.The damage loss rate of single-season middle rice yield in Changfeng County along Huaihe River continued to increase as the increasing of high temperature damage duration.But the occurrence probability decreased.The intensity grade of high temperature damage disaster loss rate which happened frequently concentrated mainly in levels I and II.The longer the high temperature damage duration in the reproductive growth stage of rice was,the bigger the damage loss rate was.But the corresponding occurrence probability was small,and vice versa.[Conclusion] The research provided the reference for assessing the high temperature disaster risk.

Effects of Short-term High Temperature Stress on the Photosynthesis of Potato in Different Growth Stages

[Objective] The aim was to study the effects of short-term high temperature stress on the photosynthesis of potato in different growth stages. [Method] Choosing powder potato named Longshu No.3 widely cultivated in Ningxia as test material,the changes of stomata conductance （Gs）,transpiration rate （Tr） and CO2 concentration difference between internal and external leaf chamber,net photosynthetic rate （Pn） and photosynthetic water use efficiency （WUE） in different growth stages under short-term high temperature were analyzed. [Result] During seedling stage,the hysteretic nature of net photosynthetic rate and CO2 concentration difference between internal and external leaf chamber of potato could be found under high temperature stress,while the change trends of stomata conductance and transpiration rate under high temperature stress were consistent to that at normal temperature,but stomata conductance and transpiration rate were higher than those at normal temperature,and CO2 concentration difference between internal and external leaf chamber affected net photosynthetic rate most obviously. During branching stage,the change trends of net photosynthetic rate,CO2 concentration difference between internal and external leaf chamber,stomata conductance and transpiration rate under high temperature stress and normal temperature were similar,but they changed abruptly and reached peak value at noon under high temperature stress,while there existed consistent variation of water use efficiency under high temperature stress and at normal temperature,and CO2 concentration difference between internal and external leaf chamber also affected net photosynthetic rate most greatly,next came transpiration rate. [Conclusion] High temperature stress affected the photosynthesis of potato in different growth stages,and it was more obvious during branching stage than seedling stage,while CO2 concentration difference between internal and external leaf chamber had the most important influence on net photosynthetic rate.

Characteristic Analysis and Forecast of Continuous High-temperature Weather in Xingtai Area of Hebei

Through the analysis of durative high-temperature weather process occurred in Xingtai area in June of 2010,and the statistics on relative humidity and 850 hPa of temperature on high temperature day in Xingtai area during 2001- 2010,it was concluded that 500 h Pa of stable warm high-pressure ridge situation and 850 hPa of strong warm air mass control were favorable circulation situations for the formation of high temperature;sinking and adiabatic warming of high-altitude air mass was an important cause of high temperature weather generation; ground humidity at 14： 00 was small,that is,the atmosphere was very dry,and it was sunny-cloudy（ high cirrus） weather,which was a necessary condition for the high temperature weather; westerly at some time was favorable condition for high temperature; 850 h Pa of temperature prediction at the station was the key.When the forecasted 850 h Pa of station temperature was 21 ℃ and above,it was reminded the forecasters in the high-temperature forecast process.

High Temperature-preventing Cultivation Technology of Single-season Middle Rice for High Yield and High Quality in Jianghuai Area

In recent years,with the global climate change,the frequency and duration of high temperature in summer and autumn have increased,causing high temperature heat damage to summer crops such as rice and maize.From the end of July to early August is the main period of high temperature occurrence,during which the daily average temperature above 30℃is a high probability event,and even the highest temperature is above 38℃,while this period coincides with the booting-blooming-filling stage of the single-season middle rice in Jianghuai,especially the middle-season indica rice,so it often leads to the degradation of rice spikelets,pollen abortion,difficulty in pollen dispersion,and even difficulty in heading,resulting in a serious decline in the seed setting rate and poor filling of grains,which finally affect the yield and quality.Based on the goal of high-yielding high-quality rice cultivation,this paper proposed targeted technical measures for single-season middle rice from the aspects of planting time sequence optimization,selection of high-temperature-resistant varieties,population construction,fertilizer and water management technology,and how to compensate for the occurrence of unexpected disasters to promote plant growth.This study provides technical support for high-yielding high-quality stress-resistant and disaster-reducing rice cultivation technology.

Inter-provincial Differences in Rice Multi-cropping Changes in Main Double-cropping Rice Area in China: Evidence from Provinces and Households

Since the early 1980 s, the multi-cropping index for rice has decreased significantly in main double-cropping rice area in China, which is the primary double-cropping rice(DCR) production area. This decline may bring challenges to food security in China because rice is the staple food for more than 60% of the Chinese population. It has been generally recognized that rapidly rising labor costs due to economic growth and urbanization in China is the key driving force of the ‘double-to-single' rice cropping system adaption. However, not all provinces have shown a dramatic decline in DCR area, and labor costs alone cannot explain this difference. To elucidate the reasons for these inter-provincial distinctions and the dynamics of rice cropping system adaption, we evaluated the influencing factors using provincial panel data from 1980 to 2015. We also used household survey data for empirical analysis to explore the mechanisms driving differences in rice multi-cropping changes. Our results indicated that the eight provinces in the study can be divided into three spatial groups based on the extent of DCR area decline, the rapidly-declining marginal, core, and stable zones. Increasing labor cost due to rapid urbanization was the key driving force of rice cropping system adaption, but the land use dynamic vary hugely among different provinces. These differences between zones were due to the interaction between labor price and accumulated temperature conditions. Therefore, increasing labor costs had the greatest impact in Zhejiang, Anhui, and Hubei, where the accumulated temperature is relatively low and rice multi-cropping index declined dramaticly. However, labor costs had little impact in Guangdong and Guangxi. Differences in accumulated temperature conditions resulted in spatially different labor demands and pressure on households during the busy season. As a result, there have been different profits and rice multi-cropping changes between provinces and zones. Because of these spatial differences, regionally appropriate policies that provide appropriate subsidies for early rice in rapidly-declining marginal zone such as Zhejiang and Hubei should be implemented. In addition, agricultural mechanization and the number of agricultural workers have facilitated double-cropping; therefore, small machinery and agricultural infrastructure construction should be further supported.

Influence of welded pores on fatigue behavior of TC17 titanium alloy welded joints subjected to gigacycle regime at room and high temperatures

Welded structures in aero-engines commonly operate in high-temperature environments,making them susceptible to reduced fatigue life and premature failure due to welding defects within the structure.Thus,the gigacycle fatigue behaviors of titanium alloy welded joints at both room temperature(RT)and 400 ℃ were investigated,aiming to uncover the mechanism behind the formation of fine granular area(FGA)surrounding welded pores.The research findings demonstrate that the S-N curves of TC17 tita-nium alloy electron beam welded joint undergo a transition from a single linear decline at RT to a bilin-ear decline at 400 ℃.However,the fatigue failure mode remains unaffected by temperatures,and crack initiation is attributed to welded pores.By utilizing the Chapetti model curve to modify the Kitagawa-Takahashi(K-T)diagram,the lower threshold stress amplitude is introduced,enabling the determination of a safe size for welded pores at 400 ℃,which is calculated to be 11.3 μm.Additionally,the Gumbel probability distribution function is employed to assess the maximum size of welded pores.Finally,based on dislocation interactions,the formation mechanism of the FGA consisting of discontinuous nanograins with high-density dislocations is elucidated.

Preparation of Zirconia-Ceria Powders with High Specific Surface Area

Zirconia-ceria mixed oxide powders were prepared by high temperature aging method.The effects of the temperature and the time of aging, cerium content and calcination on powder performance were studied.The result shows that high temperature aging is an efficient way of preparation of ZrO2-CeO2 mixed oxide powders with high specific surface area and good thermal stability, and that addition of a small amount of cerium to hydrous zirconia can promote the preparation of high specific surface area powders.

No treeline shift despite climate change over the last 70 years

Background:The recent rise in temperature and shifting precipitation regimes threaten ecosystems around the globe to different degrees.Treelines are expected to respond to climate warming by shifting to higher elevations,but it is unclear whether they can track temperature changes.Here,we integrated high-resolution aerial imagery with local climatic and topographic characteristics to study the treeline dynamic from 1945 to 2015 on the semiarid Mediterranean island of Crete,Greece.Results:During the study period,the mean annual temperature at the treeline increased by 0.81℃,while the average precipitation decreased by 170 mm.The treeline is characterized by a diffuse form,with trees growing on steep limestone slopes(>50°)and shallow soils.Moreover,the treeline elevation decreases with increasing distance from the coast and with aspect(south>north).Yet,we found no shift in the treeline over the past 70 years,despite an increase in temperature in all four study sites.However,the treeline elevation correlated strongly with topographic exposure to wind(R^(2)=0.74,p<0.001).Therefore,the temporal lag in treeline response to warming could be explained by a combination of topographic and microclimatic factors,such as the absence of a shelter effect and a decrease in moisture.Conclusion:Although there was no treeline shift over the last 70 years,climate change has already started shifting the treeline altitudinal optimum.Consequently,the lack of climate-mediated migration at the treeline should raise concerns about the threats posed by warming,such as drought damages,and wildfire,especially in the Mediterranean region.Therefore,conservation management should discuss options and needs to support adaptive management.

Challenges and Methods to Improve Well Cementing Quality for 177.8 mm Liner in Gaoshiti-Moxi Area

Gaoshiti-Moxi structure belt of An-Yue Sinian gas reservoir, which was China’s largest monomer Marine carbonate gas reservoir up to now, located in vying-dragon female temple structure group that belong to the ancient uplift slope of the middle of Sichuan. With the exploration and development of high temperature and high pressure carbonate reservoir, a large number of challenges and problems, such as long isolation section, active oil-gas show, large temperature difference, prone to super retarding cement slurry and gas channeling at flare position, have been encountered in the cementing of 177.8 mm hang-liner. In order to solve these problems, numerous measures and methods have been put into use for reducing the safety risk of cementing and improving cementing quality. The large temperature difference channeling cement slurry system, effective anti-pollution spacer and high-pressure packer type liner hanger were developed and applied for field tests in the early stage of development. In addition, equilibrium pressure cementing technology, optimizing of centralizer placement and plasma column structure, improvement of pump displacement and hold pressure while waiting on cement were used to ensure nice displacement efficiency and cementing quality. As Moxi X well for example, the cementing quality factor of merit was 40.29% and the qualification rate was up to 78.87% after adopting the cementing measures and methods above. The cementing quality was much higher than previous level and provided technical support for Gaoshiti-Moxi area.

Characterization of heat shock protein 90, 70 and their transcriptional expression patterns on high temperature in adult of Graphofita molesta （Busck）

Grapholita molesta （Busck） is a worldwide insect pest damaging stone and pome fruits. High temperature can significantly affect insect survival, development and fecundity. Heat shock protein （Hsp） genes were speculated to possess a pivotal function in response to high temperature stress. In this study, two full-length Hsp genes, Gmhsp90 and GmhspTO, were cloned from G. molesta using rapid amplification of complementary DNA ends （RACE）. The open reading frames of Gmhsp90 and Gmhsp70 obtained were 2 148 bp and 1 998 bp in length, respectively. Their deduced amino acids showed high homology to Hsp genes of other species. Subsequently, the transcriptional expression of Gmhsp90 and Gmhsp70 in G. molesta adults exposed at various temperatures （26, 29, 32, 35, 38, 41 and 44℃） for 1 h and at 41℃ for various time duration （0, 15, 30, 45, 60, 75, 90 and 105 min） were investigated via real time quantitative polymerase chain reaction （qPCR）. The relative expression levels of Gmhsp90 and Gmhsp70 in G. molesta adults were both up-regulated with the rise of temperature and time duration. In addition, the Gmhsp70 usually showed a higher transcription accumulation than Gmhsp90. Interestingly, Gmhsp90 and Gmhsp 70 in female adults could be induced much earlier than that in males, and the effective induction temperature in females was also lower than that in males. The distinct expression profiles of Gmhsp90 and Gmhsp 70 indicated that Gmhsp90 and Gmhsp 70 may play important roles in G. molesta adults responding to a thermal threat, and there is difference on induction between sexes.

Synthesis of Small-sized Coesite Under Lower Pressure

With the help of high-energy mechanical milling and a-SiO2 as the initial material, we investigated the synthesis of coesite at a high temperature and high pressure under the condition of adding a certain amount of hard Fe filling. The synthetic samples were measured by XRD and Raman spectroscopy. The results show that a small amount of small-sized coesite can be obtained under 2.5 GPa and 973 K.

Seepage Mitigation in Hydropower Dams by Optimization in Roller Compacted Concrete Interlayer (Monoliths) Joint Bonding Technology

Roller Compacted Concrete (RCC) has gained favorable recognition in hydropower and water resource dam construction. With optimization in construction technology and materials used for RCC Dams, cost is no longer a major disadvantage as compared to environmental impact, that is, wildlife habitat disruption. In as much as it has become optimal for investment in hydropower dam construction, the scourge for dam failure is still eminent, which is as a result of excessive seepage compromising the integrity of the mechanical properties of the dam. The aim of the paper is to highlight successful application methods in joint bonding to avoid excessive seepage and reduce the autogenous healing to a few years of operation. In view of optimization, this paper presents a comprehensive study on the influences of interlayer joints bonding quality from RCC mix performances and how it consolidates the RCC layers to withstand the shear strength along the interface, especially on the high dams. The case study is the RCC dam at the 750 MW Kafue Gorge Lower Hydropower Station. The scope of the study reviews the joint type judged by Modified Maturity Factor (MMF) with joint surface long time exposed in regions with dry and high temperature, technical measures of layer bonding quality control under condition of long time joint surface exposure, effects of joints shear strength and impermeability of the RCC layers when under the conditions of plastic and elasticity. The subtle observations made during the dam construction phases were with respect to the optimal use of materials in relation to RCC mix designs and the basis for equipment calibration for monitoring important data that can be referenced during analysis of shear forces acting on the RCC dam over time.

粮食功能区视角下农业高质量发展水平及区域差异研究

基于2016—2020年省级农业发展数据,综合运用改进后的熵值法、Dagum基尼系数等方法,测算了全国及粮食功能区农业高质量发展水平及差异程度,并进一步从一级指标入手,分析了引起区域差异产生和波动的原因。结果表明:(1)三大粮食功能区的农业高质量发展水平均保持上升趋势,按水平由大到小依次为“主销区、主产区、平衡区”。(2)三大粮食功能区存在区域差异,区域间的差异是总体差异的主要来源,区域内差异也出现不同程度的变动。(3)主销区内部差异波动与产业升级指标相关,主产区内部差异波动主要受产出高效和产业升级指标影响,平衡区内部差异波动源于产业升级指标中的追赶效应。(4)区域间差异主要源自产业升级指标,成果共享指标也起到部分影响作用,三大区域各具发展短板。因此,为提升我国农业高质量发展均衡性,应坚持“因地制宜”原则,以水平最低的平衡区为发力点,以产业升级指标为抓手,以各区域发展短板为突破,采取更具针对性的发展措施。

不同产地杜仲叶活性成分的定量分析

通过杜仲叶中主要活性成分绿原酸的提取率,优化杜仲叶活性成分的提取工艺,比较不同产地杜仲叶组成及含量的差异.以绿原酸为目标产物,通过单因素实验和Box-Behnken模型,并采用高效液相色谱法测定秦仲叶和华仲叶中芦丁、松脂醇二葡萄糖苷、金丝桃苷、绿原酸及没食子酸五种活性成分含量.单因素条件对两者叶的提取效果影响均为:提取温度>提取时间>乙醇体积分数>料液比.在最佳提取条件下,秦仲叶绿原酸提取率为62.94%,华仲叶绿原酸提取率为47.84%.两者叶中绿原酸含量最高,秦仲叶中芦丁、松脂醇二葡萄糖苷含量比华仲叶高出1.97倍和6.59倍,但华仲叶中金丝桃苷和绿原酸含量比秦仲叶高出1.41倍和1.16倍.本研究旨在为不同地域杜仲树种的选育以及临床上应用标准提供理论依据,帮助更加全面地评价不同产地杜仲药材质量.

热作用下花岗岩能量演变的尺度分析

【目的】为了定量探究岩石受热作用损伤的过程。【方法】从能量角度出发,通过冷却法研究实验室尺度下不同尺寸类型花岗岩试件在空气中冷却时热物理参数演变规律,讨论花岗岩受非稳态传热全过程能量吸收、能量释放及能量耗散特性,揭示非稳态过程中能量演变规律与花岗岩试件尺寸特征的内在联系。【结果】结果表明:不同尺寸类型高温花岗岩试件空冷至室温的过程中,比热持续降低;非稳态传热能量演变过程中,同一种尺寸试件耗散能与耗散比的大小与初始高温状态呈正相关;花岗岩在非稳态传热条件一致的情况下,随试件体积的增大,用于损伤的这部分能量绝对值在增加但相对值在减小;随着试件比面的增大,用于损伤的这部分能量绝对值在减小但相对值在增大。研究结果能够丰富高温岩石力学理论研究的发展。

超级中学垄断与城市内顶尖大学入学机会区域差异——基于北京市的实证研究

超级中学的发展壮大可能加剧城市内部顶尖大学入学机会的区域差异,不利于大型城市引导人口向郊区流动。基于对某顶尖大学A北京生源调查数据(2001—2021年)的分析发现,顶尖大学入学机会在北京市存在着明显的城郊差异,位于城区的超级中学与首位中学近年来分别垄断了A大学约40%与超过20%的生源;超级中学垄断降低了北京市一般高中学生的顶尖大学入学机会,但这种负面影响主要表现为对郊区一般高中学生顶尖大学入学可能性、顶尖大学生源密度及相对录取排名的冲击,城区一般高中所受影响并不明显。因此应该增加郊区优质教育资源投入,强化市级政府的资源统筹力度,同时也需要扩大优质高中的资源覆盖、加强郊区教师队伍建设、优化高中学校规划布局。

深度学习的大高差高海拔地区高程拟合方法

大高差高海拔地区的地形复杂多变,传统的高程拟合方法,如多项式拟合、曲面拟合、BP神经网络和遗传算法改进的神经网络等方法,拟合精度都有待提高。本文构建了一种基于深度学习的高程拟合方法,利用西部某铁路控制网的2020年一期二等水准测量数据,采用多层感知器(MLP)作为核心模型,通过结合RAdam优化器和GELU激活函数进行优化,该方法能够有效捕捉该地区的地形特征和高程变化规律,实现高精度的高程拟合。研究分析了不同优化器和激活函数组合对模型性能的影响,结果表明,深度学习模型在大高差高海拔地区高程拟合中表现出较佳性能,其均方误差(MSE)最低,平均绝对误差(MAE)最小,决定系数R 2最接近1,显著优于BP神经网络和遗传算法改进的神经网络方法。特别是RAdam优化器和GELU激活函数的组合,在模型性能上表现最佳。本文所构建出的深度学习大高差高程拟合方法,不仅精度较高且具有良好的泛化能力,能够适应大高差高海拔地区复杂多变的地形特征。

High-temperature failure mechanism and defect sensitivity of TC17 titanium alloy in high cycle fatigue

Crack initiation is an essential stage of fatigue process due to its direct effect on fatigue failure.However,for titanium alloys in high-temperature high cycle fatigue(HCF),the crack initiation mechanisms remain unclear and the understanding for the defect sensitivity is also lacking.In this study,a series of fatigue tests and multi-scale microstructure characterizations were conducted to explore the high-temperature failure mechanism,and the coupled effect of temperature and defect on TC17 titanium alloy in HCF.It was found that an oxygen-rich layer(ORL)was produced at specimen surface at elevated temperatures,and brittle fracture of ORL at surface played a critical role for surface crack initiation in HCF.Besides,internal crack initiation with nanograins at high temperatures was a novel finding for the titanium alloy.Based on energy dispersive spectroscopy,electron backscatter diffraction and transmission electron microscope characterizations,the competition between surface and internal crack initiations at high temperatures was related to ORL at surface and dislocation resistance in inner microstructure.The fatigue strengths of smooth specimens decreased at elevated temperatures due to the lower dislocation resistance.While the fatigue strengths of the specimens with defect were not very sensitive to the temperatures.Finally,a fatigue strength model considering the coupled effect of temperature and defect was proposed for TC17titanium alloy.