Highly efficient H-bonding charge-transfer complex for microsupercapacitors under extreme conditions of low temperatures

Owing to sluggish ionic mobility at low temperatures, supercapacitors, as well as other energy-storage devices, always suffer from severe capacity decay and even failure under extreme low-temperature circumstances. Solar-thermal-enabled self-heating promises an attractive approach to overcome this issue.Here, we report a unique H-bonding charge-transfer complex with a high photothermal conversion efficiency of 79.5% at 405 nm based on chloranilic acid and albendazole. Integrated with a microsupercapacitor, the chloranilic acid-albendazole complex(CAC) film prompts an apparent temperature increase of 22.7 °C under 1 sun illumination at-32.6 °C, effectively elevating the working temperature of devices.As a result, the rate capability of the microsupercapacitor has been significantly improved with a 17-fold increase in capacitance at a current density of 60 μA cm^(-2), leading to outstanding low-temperature performances. Importantly, the integrated device is capable of working at a low temperature of-30 °C in the open air, which demonstrates the potential of CAC in practical applications for low-temperature ultracapacitive energy-storage devices.

Study on Temporal-spatial Change Characteristics of the Extremely Low Temperature Climate Event in Winter of China

[ Objective] The research aimed to study temporal-spatial change characteristics of the extremely low temperature climate event in winter of China. [MethodI By using actual probability distribution threshold value method, EOF analysis method and the daily minimum temperature data in winter of 1961 -2008 at 195 observatories of China, temporal-spatial change characteristics of the extremely low temperature climate event in win- ter of China in 48 years were analyzed. [ Result] Threshold value calculated by actual probability distribution was higher than that by traditional method, and increase magnitude in east was bigger than that in west, which could describe climatic change situation in China in 48 years better than traditional method. Cold night number in winter of China did not decrease as latitude declined, and it was more in south and north and was less in Yellow River basin and northwest China. Cold night number was the most in northeast Inner Mongolia. Interannual change of the cold night number presented decline tendency. From the 1960s to the eady 1970s, cold night number consistently increased, and change in middle and late periods of the 1960s was severe. From the early 1970s to the middle 1980s, fluctuation of the cold night number was bigger, and increase of the cold night number was the most in 1976. Cold night number from 1986 to the 21= century continuously declined. Change of the cold night number was the most obvious in east region, Guizhou and north Guangxi. Cold night number in northeast China and north Inner Mongolia presented inverting change relationship with that in Yunnan - Kweichow Plateau and Hexi Corridor. [ Conclusion] The research provided reference for eady warning of the extremely low temoerature event in China.

MULTIMODEL CONSENSUS FORECASTING OF LOW TEMPERATURE AND ICY WEATHER OVER CENTRAL AND SOUTHERN CHINA IN EARLY 2008

Based on the daily mean temperature and 24-h accumulated total precipitation over central and southern China, the features and the possible causes of the extreme weather events with low temperature and icing conditions,which occurred in the southern part of China during early 2008, are investigated in this study. In addition, multimodel consensus forecasting experiments are conducted by using the ensemble forecasts of ECMWF, JMA, NCEP and CMA taken from the TIGGE archives. Results show that more than a third of the stations in the southern part of China were covered by the extremely abundant precipitation with a 50-a return period, and extremely low temperature with a 50-a return period occurred in the Guizhou and western Hunan province as well. For the 24- to 216-h surface temperature forecasts, the bias-removed multimodel ensemble mean with running training period(R-BREM) has the highest forecast skill of all individual models and multimodel consensus techniques. Taking the RMSEs of the ECMWF 96-h forecasts as the criterion, the forecast time of the surface temperature may be prolonged to 192 h over the southeastern coast of China by using the R-BREM technique. For the sprinkle forecasts over central and southern China, the R-BREM technique has the best performance in terms of threat scores(TS) for the 24- to 192-h forecasts except for the 72-h forecasts among all individual models and multimodel consensus techniques. For the moderate rain, the forecast skill of the R-BREM technique is superior to those of individual models and multimodel ensemble mean.

Distribution Characteristics of Winter Continuous Extreme Low Temperature in China

[Objective] The research aimed to study the distribution characteristics of winter continuous extreme low temperature in China. [Method] Based on the daily minimum temperature data in winter during 1961-2008 in 195 observatories, the continuous extreme low temperature event (cold night) which happened in winter in China and the distribution characteristics of accumulated temperature anomaly in 48 years were analyzed by using the actual probability distribution threshold method. [Result] Besides in Northeast China, Northwest China and Qinghai-Tibet Plateau where the geographical position was northerly, and the altitude was high, the long-time (above 5 d) extreme low temperature event was also easy to happen in the south of Yangtze River, especially in Guizhou, Guangxi, Hunan and so on. The continuous extreme low temperature event in the middle and lower reaches of Yellow River was the least. Started from the metaphase of the 1980s, the frequency trend of continuous extreme low temperature event decreased. But in 1992, 2000 and 2007, the low temperature event which continued above 7 d was more than the average. The accumulated cold in January in 48 years was the strongest. The second one was in February, and the smallest was in December. The accumulated cold in Northeast China and the north of Inner Mongolia was the biggest in December and January. The accumulated cold in the north of Xinjiang was the biggest in February. In the whole winter, the accumulated cold in Qinghai-Tibet Plateau was the smallest. The chilling injury was easier to happen in Guizhou, Guangxi and Hunan than other south areas in December and February. The occurrence probability of chilling injury in most areas of Szechwan Basin, Yunnan and Qinling Mountains in central China was smaller than that in other areas. [Conclusion] The research provided the reference basis for analyzing the influence of chilling injury on the agriculture in China.

Spatial-Temporal Characteristics of Regional Extreme Low Temperature Events in China during 1960-2009

An objective identification technique is used to detect regional extreme low temperature events(RELTE) in China during 1960-2009.Their spatial-temporal characteristics are analyzed.The results indicate that the lowest temperatures of RELTE,together with the frequency distribution of the geometric latitude center,exhibit a double-peak feature.The RELTE frequently happen near the geometric area of 30 N and 42 N before the mid-1980s,but shifted afterwards to 30 N.During 1960-2009,the frequency,intensity,and the maximum impacted area of RELTE show overall decreasing trends.Due to the contribution of RELTE,with long duration and large spatial range,which account for 10% of the total RELTE,there is a significant turning point in the late 1980s.A change to a much more steady state after the late 1990s is identified.In addition,the integrated indices of RELTE are classified and analyzed.

Spatiotemporal distribution characteristics and attribution of extreme regional low temperature event

Based on an objective identification technique for regional low temperature event（OITRLTE）, the daily minimum temperature in China has been detected from 1960 to 2013. During this period, there were 60 regional extreme low temperature events（ERLTEs）, which are included in the 690 regional low temperature events（RLTEs）. The 60 ERLTEs are analyzed in this paper. The results show that in the last 50 years, the intensity of the ERLTEs has become weak; the number of lasted days has decreased; and, the affected area has become small. However, that situation has changed in this century.In terms of spatial distribution, the high intensity regions are mainly in Northern China while the high frequency regions concentrate in Central and Eastern China. According to the affected area of each event, the 60 ERLTEs are classified into six types. The atmospheric circulation background fields which correspond to these types are also analyzed. The results show that, influenced by stronger blocking highs of Ural and Lake Baikal, as well as stronger southward polar vortex and East Asia major trough at 500-h Pa geopotential height, cold air from high latitudes is guided to move southward and abnormal northerly winds at 850 h Pa makes the cold air blow into China along diverse paths, thereby forming different types of regional extreme low temperatures in winter.

Ohmic Contact at Al/TiO_2/n-Ge Interface with TiO_2 Deposited at Extremely Low Temperature

TiO2deposited at extremely low temperature of 120°C by atomic layer deposition is inserted between metal and n-Ge to relieve the Fermi level pinning. X-ray photoelectron spectroscopy and cross-sectional transmission electron microscopy indicate that the lower deposition temperature tends to effectively eliminate the formation of GeOxto reduce the tunneling resistance. Compared with TiO2deposited at higher temperature of 250°C,there are more oxygen vacancies in lower-temperature-deposited TiO2, which will dope TiO2contributing to the lower tunneling resistance. Al/TiO2/n-Ge metal-insulator-semiconductor diodes with 2 nm 120°C deposited TiO2achieves 2496 times of current density at-0.1 V compared with the device without the TiO2interface layer case, and is 8.85 times larger than that with 250°C deposited TiO2. Thus inserting extremely low temperature deposited TiO2to depin the Fermi level for n-Ge may be a better choice.

Planck’s Oscillators at Low Temperatures and Haken’s Perturbation Approach to the Quantum Oscillators Reconsidered

In the first step the extremal values of the vibrational specific heat and entropy represented by the Planck oscillators at the low temperatures could be calculated. The positions of the extrema are defined by the dimensionless ratios between the quanta of the vibrational energy and products of the actual temperature multiplied by the Boltzmann constant. It became evident that position of a local maximum obtained for the Planck’s average energy of a vibration mode and position of a local maximum of entropy are the same. In the next step the Haken’s time-dependent perturbation approach to the pair of quantum non-degenerate Schr?dinger eigenstates of energy is re-examined. An averaging process done on the time variable leads to a very simple formula for the coefficients entering the perturbation terms.

Identifying Regional Prolonged Low Temperature Events in China

This study examined regional prolonged low temperature （PLT） events in China from the observational station data for the period 1960–2008 using the new criteria. The new definition of a site PLT event is that the daily minimum temperature does not exceed the 10th percentile threshold of the local daily minimum temperature climatology for at least 5 days at a station. The regional PLT event is defined as at least five adjacent stations exhibiting site PLT simultaneously for 5 d. Under the new definition, 552 regional PLT events were identified, and three indices： duration, extent, and intensity, as well as a comprehensive index （CI） were used to quantify the event severity. In addition, geographical patterns and temporal variations of regional PLT events were investigated using three event categories： strong, moderate, and weak. Spatially, strong events were mainly located in the north of Xinjiang and along the Yangtze River to the south of the Yangtze River; moderate events occurred in Xinjiang and south of the Yangtze River; and weak events occurred south of the Yellow River. The variation for the annual frequency of regional PLT events in China in the last 49 years showed a significant decreasing trend with a rate of-1.99 times per decade, and the significant transition decade was the 1980s.

2023年春末阿克苏东部两次极端低温过程对比分析

2023年4月23日和5月6日阿克苏地区东部出现极端低温霜冻天气(简称“4.23”过程和“5.6”过程),尤其“5.6”过程库车市出现历史最晚终霜。基于常规观测、L波段探空、NCEP/NCAR1°×1°逐6 h再分析等资料,利用天气动力学方法对比分析2次极端低温过程环流背景,高低空配置、冷空气及冷平流强度、锋生作用等,探讨极端低温霜冻成因。结果表明:(1)两者有共性也有差异,共性表现在2次过程500 hPa阿克苏地区东部均受低槽(低涡)后部西北气流携带冷空气影响,且温度梯度大,锋区增强;均有深厚冷平流自阿克苏西部沿高层偏北气流向阿克苏地区东部低层下传;低温时段贴地层均有逆温和明显锋生,锋生与冷空气进入南疆盆地的路径及低温持续时间对应,且高层能量锋区较强,中低层锋区在增强过程中有斜压不稳定发展;均在霜冻出现前6 h冷平流强度增至最大,冷平流与8℃以上降温区域对应较好,且850 hPa温度降至3~4℃,对低温霜冻预报有一定指示性。(2)不同点在于“4.23”过程冷空气为西北路径,西翻和东灌冷空气共同影响阿克苏地区,贴地层逆温明显偏强,为辐射+平流降温;“5.6”过程冷空气为偏北路径,较强冷高压翻越天山进入南疆盆地,同时有东灌冷空气补充,影响范围大、逆温弱但整层降温明显,以辐射降温为主。(3)“5.6”过程低涡在新疆维持时间长,其冷空气及锋区强度、假相当位温梯度及影响时间均较“4.23”过程更强,灾害更重。

合成基润滑油聚α-烯烃低温摩擦润滑性能研究

在低温条件下,润滑油黏度变大,流动性变差,添加剂活性降低,对润滑性能产生显著影响。为研究PAO润滑油的低温摩擦润滑性能,以不同黏度级别PAO基础油为研究对象,采用流变仪MCR302、SRV摩擦磨损试验机,研究PAO润滑油样及添加极压抗磨添加剂的油样在低温条件下的流变性能和磨损润滑性能。试验结果表明:在低温环境下,随着温度降低,PAO油样的黏度急剧增大,黏度越大的油样其受低温条件影响越明显;PAO油样在低温环境下,表现出明显的剪切稀化现象;低温环境使得极压抗磨剂添加剂的活性变低,添加剂并未表现出减摩抗磨作用。因此,低温试验条件对PAO基础油和添加剂的摩擦学性能产生显著影响,阻碍了基础油和润滑油添加剂减摩抗磨作用的发挥。

2024年2月大气环流和天气分析

2024年2月北半球大气环流主要特征表现为极涡呈偶极型,东半球极涡中心位于鄂霍次克海到勘察加半岛上空,较常年同期偏强,影响我国的冷空气路径偏东;中纬度环流呈三波型,位于西伯利亚的平均槽较常年偏强,西风带短波槽活动频繁;南支槽位置偏东,西太平洋副热带高压显著偏强。2月全国平均气温为-1.8℃,较常年同期(-1.3℃)偏低0.5℃;平均降水量为22.5 mm,较常年同期(16.3 mm)偏多38%。月内有3次主要冷空气过程,其中2月17—22日强寒潮造成剧烈降温和显著低温。受南下冷空气和强盛的西南暖湿气流共同影响,月内出现2次大范围持续性低温雨雪冰冻天气过程,冻雨强度大、范围广,降水量具有极端性,对春运造成严重影响。此外,2月还出现了年度首次沙尘和强对流天气过程。

揭阳冬季低温及其极端事件与低频振荡的关系

基于1981-2020年揭阳市国家站逐日最低气温和NCEP/NCAR再分析资料,采用相对阈值和功率谱分析方法研究了揭阳冬季最低气温及持续性极端低温事件(PECE)与低频振荡的联系。结果表明:揭阳市冬季最低气温存在显著10~30 d振荡(准双周振荡)与30~90 d振荡(季节内振荡)。冬季最低气温的低频振荡对PECE的发生起重要调制作用,60%的PECE同时受10~30和30~90 d变率耦合影响,30%的PECE仅受10~30 d变率调制,10%的事件仅受30~90 d变率调控。中高纬低频环流波列通过调制西伯利亚高压和东亚大槽季节内尺度上的位置及强度变化来影响低频冷空气的南侵,进而引起揭阳市最低气温低频分量的持续下降,有利于PECE的发生。

CMIP6模式对青藏高原极端温度的模拟能力评估及其未来预估

为探究新一代国际耦合模式比较计划第六阶段(CMIP6)气候模式对青藏高原未来极端温度的模拟能力,使用1995-2014年CMIP6历史模拟实验数据和观测数据CN05.1,通过对年频次及时间空间分布的对比分析,评估8个全球气候模式对青藏高原极端高温和极端低温2个气象要素的模拟性能,并对未来在不同排放情景下极端温度事件演变趋势进行预估。结果表明,尽管所选模式模拟能力有差异,但都能合理地再现青藏高原极端高温和极端低温西部冷、东部暖的分布特征;预估结果指出未来高原极端高温事件出现的概率会增大,极端低温事件将会减少。极端温度有显著上升趋势,整体上极端低温的增温趋势比极端高温更明显,并在未来共享社会经济路径(shared socioeconomic path,SSP)SSP5~8.5高排放情境下趋势更剧烈。未来极端气温事件空间分布差异变得更加显著,藏北高原中西部和柴达木盆地有明显增温趋势,而藏南地区变化不显著。

准确测量GIS产品极限低温下的气体泄漏

分析了影响GIS产品极限低温下气体泄漏测量的两大关键因素,即产品的不规则扣罩容积及SF_(6)体积比浓度,介绍了如何控制关键因素的准确测量,从而准确测量GIS产品极限低温至-40℃下的SF_(6)年泄漏率。通过追踪定量CH_(4)标样可以精确计算产品的不规则扣罩容积,通过间接加热气样法可以长时间准确监测低温至-40℃下SF_(6)气体的体积比浓度。采取有效的试验验证了测量方法的可靠性。

1961—2017年华北地区温度相关高影响天气气候事件变化特征分析

利用华北地区85个气象站1961—2017年地面均一化日值资料,统计分析了华北地区年平均最高(低)气温、极端最低气温、高温热浪以及寒潮、霜冻等高影响天气气候事件的时空分布特征。结果表明:(1)华北地区年平均最低气温升温速率(0.45℃/10 a)高于最高气温升温速率(0.27℃/10 a),气温日较差以0.18℃/10 a的速率减小。最高气温在内蒙古中部及北部部分地区和山西中南部地区的增加趋势相对更大,最低气温在内蒙古大部、山西东北部、河北中部和京津地区的增温更明显。(2)年平均高温热浪日数呈明显增加的趋势(0.44 d/10 a),20世纪90年代之后尤为明显。高温热浪日数的大值区集中在华北南部和西部;除河北南部部分地区趋势值为负外,华北大部分地区高温热浪日数呈增加趋势。(3)平均年极端最低气温呈显著升高趋势(0.53℃/10 a),冷夜天数显著下降(-4.7 d/10 a),暖夜天数显著上升(3.8 d/10 a),冷日天数呈下降趋势(-2.4 d/10 a)。年平均寒潮频次显著减少(-0.5次/10 a),呈“北部多、南部少”的空间分布。平均霜冻日数以3.5 d/10 a的速率减少,20世纪80年代之后尤为明显;除山西西北部和内蒙古东南部个别地区外,华北大部分地区霜冻日数呈减少趋势。(4)不同分区的对比结果显示,天津对气候暖化响应最敏感,其次是内蒙古西部;山西最不敏感(尤其是对低温相关要素指标),其次是河北(尤其是对高温相关要素指标)。研究结果有助于进一步认识华北地区温度相关高影响天气气候事件的区域性特征。

竹类植物在北京地区的抗寒性分析与评价

为了探索竹类植物在北京地区的抗寒性及园林应用前景,运用层次分析法(AHP)和K-means聚类分析法对北京植物园60种竹类植物进行了抗寒性分析与评价。评价模型由适应性、更新能力和观赏性3个评价准则及相关的11个评价因子构成。结果表明:评价等级为Ⅰ级竹类植物28种,包括安吉金竹、阔叶箬竹、金镶玉竹、早园竹、鹅毛竹等,占总数的46.7%,这类植物抗寒性强,在北京地区可广泛推广应用;Ⅱ级竹类植物11种,包括白哺鸡竹、善变箬竹、髯毛箬竹等,占总数的18.3%,这类植物有一定抗寒性,可适当推广应用;Ⅲ级竹类植物17种,包括黄槽斑竹、美丽箬竹等,这类植物抗寒性一般,需要在特定的环境中应用;Ⅳ级竹类植物4种,包括白纹东根笹、对花竹、黄皮绿筋竹等,这类植物抗寒性差,可在特定条件下小面积栽植。

低温极端载荷作用下船艏结构损伤演化过程研究

目的 掌握船舶在极地低温极端环境中航行时,船舶艏部结构遭遇冰山等极端载荷作用下的主要参数对结构损伤演化过程的影响,揭示船舶艏部结构的失效机理。方法 以船舶艏部结构为研究对象,基于数值仿真方法,开展不同碰撞场景、环境温度、撞击速度、冰体塑性应变、船体材料本构模型、撞击角度等参数对结构损伤的影响研究。结果 建立了数值仿真简化模型,获得了不同参数对结构损伤的影响规律。结论 材料模型对船体结构损伤的影响较小。随着航速增加、撞击角度增大,船体损伤范围增大。随着船体材料性能增强,撞击区刚度增大,船体结构损伤范围减小。形成的损伤演化模拟方法可为极地极端环境下船舶结构损伤演化分析提供技术手段。

极端低温下外啮合齿轮泵流量脉动特性分析

油液黏度随着温度降低而增大,严重影响齿轮泵在低温中的运转性能。针对外啮合齿轮泵在极端低温下的流量脉动及启动力矩大的问题,建立低温下外啮合齿轮泵的数学模型,通过有限元计算分析了不同温度下齿轮泵的启动力矩、流量脉动特性,获得了在-40~0℃温度范围内外啮合齿轮泵的启动力矩、流量脉动、流量不均匀系数和容积效率的变化规律。研究结果表明:当齿轮泵转速和进出口压力一定时,由于-40~0℃低温环境中齿轮泵油液黏度增加,齿顶间隙泄漏减小,齿轮泵容积效率提高;而齿轮泵黏性摩擦功率损失增加,导致驱动转矩增加。

麦二叉蚜过冷却能力和低温存活率研究

为弄清麦二叉蚜耐寒性,研究分析了1龄若蚜和无翅成蚜的过冷却能力和低温存活率,结果发现:麦二叉蚜1龄若蚜的过冷点和结冰点分别为-26.7±0.68℃和-26.3±0.70℃,均显著低于无翅成蚜的过冷点(-22.8±3.85℃)和结冰点(-19.3±3.80℃),且1龄若蚜的过冷却点和结冰点波动范围较小,分别在-27.7~-24.7℃和-27.5~-24.4℃之间,而无翅成蚜的过冷却点和结冰点波动范围较大,分别在-26.7~-14.2℃和-24.7~-11.6℃之间。与此同时,低温存活率结果发现,1龄若蚜80%死亡率的温度是10℃左右,无翅成蚜80%死亡率的温度是-9℃左右,表明麦二叉蚜耐寒性较强,而且1~龄若蚜的耐寒能力较无翅成蚜强。