Carbon‐based materials for all‐solid‐state zinc–air batteries

Solid‐state Zn–air batteries(ZABs)hold great potential for application in wearable and flexible electronics.However,further commercialization of current ZABs is still limited by the poor stability and low energy efficiency.It is,thus,crucial to develop efficient catalysts as well as optimize the solid electrolyte system to unveil potential of the ZAB technology.Due to the low cost and versatility in tailoring the structures and properties,carbon materials have been extensively used as the conductive substrates,catalytic air electrodes,and important components in the electrolytes for the solid‐state ZABs.Within this context,we discuss the challenges facing current solid‐state ZABs and summarize the strategies developed to modify properties of carbon‐based electrodes and electrolytes.We highlight the metal−organic framework/covalent organic framework‐based electrodes,heteroatom‐doped carbon,and the composites formed of carbon with metal oxides/sulfides/phosphides.We also briefly discuss the progress of graphene oxide‐based solid electrolyte.

State of Air Quality in Malawi

Air pollution in Malawi is recognized as one of the key environmental issues. Out of nine key issues it is ranked eighth on priority issues. This has led to lagging behind in terms of research and reporting on the issue. However, the Malawi Government has made strides in implementing policies, acts and programs that are directly or indirectly concerned with the improvement and abatement of air quality to meet the millennium development goals (MDGs) especially goal number 7. The inventories and studies show that air quality in Malawi is still good, but future anticipated air quality problems are cause for worry such as impact on human health, global climate change and ozone depletion. Trends in consumption of ozone depleting substances (ODS) show a remarkable drive towards total reduction. Emissions standards are in place in line with World Health Organization (WHO) guidelines. Recommendations on how to deal with air quality issues have been proposed in the national state of environmental report (NSOER) in that: 1) there is a need for an operational framework for climate change programs in Malawi and;2) there is a need to unify climate change policies dealing with enforcement of ODS phasing out, alternative energy sources, emissions from vehicles and industries, and institutional and human resource capacity.

An Air Mass Based Approach to the Establishment of Spring Season Synoptic Characteristics in the Northeast United States

The Northeast United States spring is indicative of major meteorological and biological change though the seasonal boundaries are difficult to define and may even be changing with global climate warming. This research aims to obtain a synoptic meteorological definition of the spring season through an assessment of air mass frequency over the past 60 years. The validity of recent speculations that the onset and termination of spring have changed in recent decades with global change is also examined. The Spatial Synoptic Classification is utilized to define daily air masses over the region. Annual and seasonal baseline frequencies are identified and their differences are acquired to characterize the season. Seasonal frequency departures of the early and late segments of the period of record are calculated and examined for practical and statistical significance. The daily boundaries of early and late spring are also isolated and assessed across the period of record to identify important changes in the season’s initiation and termination through time. Results indicate that the Northeast spring season is dominated by dry air masses, mainly the Dry Moderate and Dry Polar types. Prior to 1975, more polar air masses are detected while after 1975 more moderate and tropical types are identified. Late spring is characterized by increased variability in all moist air mass frequencies. These findings indicate that, from a synoptic perspective, the season is dry through time but modern springs are also warmer than those of past decades and the initiation of the season is likely arriving earlier. The end of the season represents more variable day-to-day air mass conditions in modern times than detected in past decades.

Stiffness Characteristics of a Basic Nonlinear Air Spring Model

This study predicts the characteristics of a compressible polytropic air spring model. A second-order nonlinear autonomous air spring model is presented. The proposed model is based on the assumption that polytropic processes occur. Isothermal and isentropic compression and expansion of the air within the spring chambers are the two scenarios that are taken into consideration. In these situations, the air inside the spring chambers compresses and expands, resulting in nonlinear spring restoring forces. The MATLAB/Simulink software environment is used to build a numerical simulation model for the dynamic behavior of the air spring. To quantify the values of the stiffnesses of the proposed models, a numerical solution is run over time for various values of the design parameters. The isentropic process case has a higher dynamic air spring stiffness than the isothermal process case, according to the results. The size of the air spring chamber and the area of the air spring piston influence the air spring stiffness in both situations. It is demonstrated that the stiffness of the air spring increases linearly with increasing piston area and decreases nonlinearly with increasing air chamber length. As long as the ratio of the vibration’s amplitude to the air spring’s chamber length is small, there is good agreement in both scenarios between the linearized model and the full nonlinear model. This implies that linear modeling is a reasonable approximation of the complete nonlinear model in this particular scenario.

Significant Shift of Ambient Night-Time Air Temperature during Rice Growing Season in Major US Rice States

Heat stress studies in rice (Oryza sativa sp.) under extreme weather scenarios generally use constant temperatures to influence the crop responses without relation to actual weather changes. These heat stress studies may have limited implications for future crop yields because elevated temperatures are not based on local temperature fluctuations. This study investigated the night-time air temperature pattern and assessed the status and reliability of available weather station data in four major rice growing states;Arkansas (AR), California (CA), Louisiana (LA) and Texas (TX) using four public weather station databases. Hourly and daily night-time air temperatures from 20:00 to 06:00 were obtained from 1940 to 2018 during the rice growing period. During the 67-year period, a significant increase of 1.12°C and 0.53°C in seasonal night air temperature occurred in CA and AR (P ≤ 0.001) while LA and TX showed minimal to no increase in night air temperature. Across all rice states and years, night air temperature fluctuations ranged between ±0.2°C and ±4°C with the greatest occurred in CA (2.9°C) and AR (4.5°C). Mean night-time air temperature across all states ranged from 22.6°C to 29.5°C with a rate of increase of 0.01°C to 0.02°C per year since 1941. Due to a relatively smaller spatial dataset (from 1941-2018), trend analyses for AR, TX and LA showed modest bias with root mean square errors (RMSE) of 0.5°C to 1.1°C of absolute mean temperature across all locations. Results in this study showed seasonal night-time air temperature change occurred in some major US rice producing states during the last 67-years. This study highlights the need for more weather stations near agricultural farms to reliably derive actual temperature patterns in the rice growing regions.

全固态Li-O_2(air)电池研究进展

锂空气电池[Li-O_2(air)]具有极高的能量密度,引起了越来越多的关注。全固态Li-O_2(air)电池使用不易燃的无机固体锂离子导体材料作为电池电解质,大大提高了电池的安全性能。研发具有高离子电导率、高稳定性的固体电解质对全固态Li-O_2(air)电池的发展起到极大的推动作用。此外,研发高性能正极催化剂、采取合理的技术手段提高电极/固体电解质界面性能也是全固态Li-O_2(air)电池面临的挑战。分别从正极、负极、固体电解质以及电极/电解质界面等方面对全固态Li-O_2(air)电池进行综述。

Li4-xSbxSn1-xS4 solid solutions for air-stable solid electrolytes

The sulfide solid electrolytes have the characteristics of high ionic conductivity and low grain boundary resistance, which make them suitable for bulk-type all-solid-state batteries. However, most of them suffer from poor stability in air. Here, we explore the air stable sulfide solid electrolytes in Li4-xSbxSn1-xS4 system. The solid solutions of Li4-xSbxSn1-xS4(0 ≤ x ≤ 0.5) can be formed in Li4-xSbxSn1-xS4 system. Li3.8 Sb0.2 Sn0.8 S4 achieves the highest ionic conductivity of 3.5 × 10-4 S cm-1 in this system,which is 5 times as that of Li4 Sn S4 and 3 orders of magnitude higher than that of Li3 Sb S4, respectively. Li3.8 Sb0.2 Sn0.8 S4 crystallizes into the same structure with high ionic conductivity phase of β-Li3 PS4. Moreover, Li3.8 Sb0.2 Sn0.8 S4 owns good stability in humid air. Matching with LiCoO2 and Li4 Ti5 O12,Li3.8 Sb0.2 Sn0.8 S4 exhibits the potential to be applied in all-solid-state batteries.

Analysis of the Zonal Mean Atmospheric Climate State in IAP/ LASG GOALS Model Simulations

The results of four versions of IAP/LASG Global Ocean-Atmosphere-Land System Model (GOALS) are analyzed separately over the oceans and over continents, and compared with observed data. Some fundamental atmospheric variables including surface air temperature (SAT), sea level pressure (SLP) and precipitation are examined to evaluate the ability of the GOALS model to simulate the contemporary climate and climate variability. In general, all four versions of the GOALS model are capable of reproducing the main features of the mean state and seasonal variation of the observed climate with reasonable accuracy. The evaluation also reveals some weakness of the model. According to this study, we can clearly see that the essential discrepancy of global averaged SLP lies over the continents in boreal summer. The simulated higher SAT over land versus the observed is mainly due to the effect of the land surface process. It is worth noting the underestimation by simulated precipitation rates mostly appears over the oceans, yet over-land precipitation is higher in high and middle latitudes than the observed for the boreal winter. Through intercomparisons among different versions of the model, it can be clearly seen that the incorporation of the diurnal cycle of solar radiation apparently improves the simulation of SAT, especially in the low and middle latitudes over land. Also, the introduction of the diurnal cycle shows a great improvement in precipitation in tropical continents and wintertime precipitation in high and middle latitudes. Furthermore, based on the daily flux anomaly exchange scheme (DFA), the latest version of GOALS model simulated over-ocean temperature variability is improved in the low and middle latitudes. Having compared the standard deviation of the annual mean surface air temperature (SAT) simulated by the GOALS model to observation, it is found that all four versions of the GOALS model underestimate surface air temperature variability over both oceans and land relative to observations. Several factors that may contribute to these differences between simulated and observed temperature variability are identified.

The Contribution of Greenhouse Gas Emissions on Future Acid Rain in States of Gulf Cooperation Council: Measures to Adopt

Air pollution is one of the serious problems facing the world. This is mainly due to production and consumption of fossil fuels. Sulphur dioxide (SO2) and oxides of nitrogen (NOx) emissions could affect human health and destroy vegetation through acid deposition and cause transboundary air pollution. Currently, there are no regional ambient SO2 and NOx regulations and control measures of many developing countries including GCC countries. This paper reviewed the experiences of the past acid rain pollution problems in United States, Canada, Europe, Japan and China. In addition, the plausible control measures through application of air pollution abatement technologies, market based regulations were discussed. The study recommended that suitable and locally based measures could be adopted by GCC states to prevent future occurrence of acid rain within the region and beyond.

基于Na-BP-DME@C阳极的长寿命准固态钠-空气电池

钠-空气电池因其能量密度高、成本低而成为金属-空气电池领域的研究热点。然而,以金属钠为阳极的钠-空气电池存在钠枝晶生长、金属钠界面稳定性差以及金属钠的反应活性高等问题,限制了钠-空气电池的快速发展。为解决上述问题,将联苯钠与导电炭黑复合材料Na-BP-DME@C作为阳极,单壁碳纳米角(SWCHNs)作为催化剂,构建准固态钠-空气电池。基于Na-BP-DME@C阳极的准固态钠-空气电池表现出优异的电化学性能,其电压差为1.5 V,功率密度为3.32 mW/cm^(2),在0.1 mA/cm^(2)电流密度下可稳定循环459 h(约459次)。

基于BIRCH聚类的航空器自主运行风险状态评价

为解决自主运行模式下航空器风险评价指标缺失和风险状态实时评估困难等问题,提出1种自主运行模式下航空器风险状态评价方法。从航空器冲突、气象规避区侵入、操纵裕度3个方面建立风险状态评价指标体系,运用BIRCH算法建立聚类特征树对多维航空器特征样本进行风险模型训练,引入增量式聚类的概念,更新特征树,实时评估动态目标航空器的风险状态。然后,以广州05扇区为运行场景展开仿真实验。研究结果表明:所提方法准确度达99.5%,平均计算时间约为0.0249 s。研究结果可有效支撑自主运行理念实施,提高风险预警能力,保障航空器自主运行安全。

考虑热舒适度的居民空调负荷调控潜力差异化评估

居民空调负荷是电力系统重要的灵活性资源,评估其调控潜力有助于负荷高效管理,促进节能减排。然而,受资金成本、数据存储和隐私保护等因素制约,居民空调状态及参数难以直接测量,差异化评估不同居民空调负荷的调控潜力存在困难。此外,居民使用空调是为了满足自身的热舒适度要求。若评估空调负荷调控潜力时忽视热舒适度限制,将导致评估值过高,降低负荷管理策略的有效性。因此,提出一种考虑热舒适度的居民空调负荷调控潜力差异化评估方法。该方法首先建立居民热舒适度及空调热动力学模型,提取影响居民热舒适度和空调负荷的关键参数;然后,利用隐马尔可夫模型和维特比算法辨识空调状态及参数;在此基础上,计算不同居民热舒适度可接受范围内的空调负荷调控潜力。基于真实居民负荷数据的算例分析表明,所提方法能够准确辨识居民空调状态并有效评估满足居民热舒适度要求的空调负荷调控潜力。

基于改进舰尾流模型和多层耦合分析的机载雷达测量建模

为提高复杂海洋环境中无人舰载机(Unmanned carrier-based aircraft, UCA)自动着舰时导航定位的准确性,研究舰尾流对机载雷达测量过程的动态影响问题,建立一种基于多层级耦合性分析的测量影响动态建模分析方法.首先,利用直接分解法和前向差分法建立一种基于离散化状态空间的时变舰尾流模型,以克服传统传递函数方法存在的局限性;其次,基于舰尾流各分量均与飞机飞行速度相关的客观事实,通过在时变系统中考虑舰尾流分量间的相互作用关系来构建一种更符合实际系统特征的分量自耦合舰尾流模型;紧接着,采用UCA姿态角变化能够改变坐标转换矩阵的思想,研究舰尾流与UCA位姿变化间的耦合联系,提出一种准确性更高的舰尾流对UCA位姿的深度影响模型;然后,以航母姿态变化对舰载雷达测量结果的影响模型为基础,通过考虑本研究场景的内在特性,建立UCA姿态变化对雷达测量结果的影响模型分析方法;紧接着,采用示意图方式获得位移变化对机载雷达测量结果的影响模型;最后,针对舰船受海洋大气(风、浪、流)干扰而出现失速这一现象,建立实际海洋环境中舰尾流对机载雷达测量结果的非线性非高斯影响分析模型.仿真实验研究验证了上述模型分析方法的有效性和优越性.

U75V钢轨自然空冷过程的温度及固态相变特性

在线热处理是百米U75V钢轨的主要强韧化手段。热处理过程中会出现由于钢轨纵向(长度方向)不同位置进入热处理机组前所经历的自然空冷时间不同而导致纵向开淬温度不一致的问题。开淬温度是影响百米钢轨纵向性能均匀性的重要因素。研究了U75V钢轨轧后自然空冷过程的温度和固态相变特性。按目前生产流程,钢轨轧制和热处理工艺间的时间间隔应小于238 s。生产时采用对轧后钢轨的后端适当补热以及缩短轧制和热处理的时间间隔等方法来减小钢轨纵向开淬温差,有利于提高百米钢轨纵向性能均匀性。

压缩空气点火的无电烟火泵浦激光技术

为了解决传统固体烟火泵浦激光器点火效率低和电能依赖的问题,根据绝热压缩原理,设计使用了完全无电的压缩空气点燃烟火药泵浦Nd:YAG激光介质,提高了点火同步性和烟火药燃烧效率,实现了激光输出阈值药剂量10 mg,使用30 mg KClO4/Zr药剂,获得了30.2 mJ的激光能量,脉冲宽度10 ms,为小型无电高能激光器提供了一条新的实现路径。

川剧脸谱艺术在现代时装中的研究与应用

川剧作为巴蜀地区文化和传统戏剧文化的杰出代表,在2006年被纳为国家非物质文化遗产名录,其中“变脸”更是川剧戏曲中非常具有代表性的一种表演形式。随着快餐时代的来临,冗长繁琐的戏曲服饰渐渐淹没在科技化的浪潮之中。网络时代的到来既是挑战也是机遇,想要继承和发扬川剧脸谱文化,唯有紧跟时代潮流。将川剧脸谱艺术以一种独特的形式融入时装设计之中,让川剧脸谱元素在现代时装美学的基础上进行创新诠释,凸显脸谱文化的鲜明特色。并且深入研究川剧脸谱元素的色彩及图案,探寻脸谱图案与服装材料相结合的表现形式,致力于创造出多元化且符合现代个性审美需求的服装。本人尝试将传统元素作为国风文化推向市场,兼并文化创新,弘扬东方神韵,进行文化输出。

基于大指令变化率下的防空导弹姿态控制方法

针对防空导弹的目标机动性较强带来的姿态控制品质变差的问题,提出一种事件触发控制方法。首先分析了由于目标机动性过强导致的指令变化率未知,以及指令变化率过大导致稳态误差较大的原因。针对此问题引入非线性最速跟踪微分器获取指令变化率,研究指令变化率与姿态角误差之间关系,定义稳态效应指标,并在该指标基础上设计了基于事件触发的新增控制量。采用滑模控制和扰动观测器使系统在指令变化率较大条件下的稳态误差被抑制在5%误差带之内。在工程实践的背景下,数值仿真考虑了气动参数拉偏以及执行机构限幅,仿真结果验证了设计的控制系统的有效性。

3-2型陶瓷-空气复合材料振动状态的研究

3-2型陶瓷-空气复合材料是在1-3型压电复合材料的结构基础上改进而来。3-2型压电材料由PZT-5A和空气复合而成。首先使用ANSYS有限元仿真软件的模态分析研究了3-2型压电复合材料做厚度伸缩振动。其次通过谐响应分析了敏感元件在正弦信号激励下的稳态响应,讨论了压电材料陶瓷体积分数对其振动特性的影响,研究了不同体积分数压电陶瓷材料在厚度振动谐振频率下的振动位移。最后通过实验制备了3-2型压电材料的实物样品,使用激光测振仪测量压电振子的振动状况,并对仿真数据进行验证。结果表明,在正弦信号激励下,3-2型复合材料的振动模态为厚度伸缩振动,振动位移最大值为3.840 nm(单位电压下),陶瓷体积占比的变化不会对振动位移产生太大影响。

一种基于物联网的变压器风冷控制系统及控制方法

由于当前国内常用的强油循环变压器冷却设备的控制方法效果欠佳,本文提出一种基于物联网的变压器风冷控制系统及控制方法,该系统包括无线油温传感单元、无线负荷传感单元、风机状态传感单元及无线温湿度环境传感单元和风冷主控单元。所述风冷主控单元与各传感单元基于无线构建传感采集网,获取变压器负荷、变压器顶层油温、环境温度以及风机运行状态,综合诊断变压器当前运行状态,不断优化变压器风冷控制策略,大幅提升风冷系统运行效率及效果。

动态下某电子工厂外延工序工艺设备排风对洁净室气流组织的影响研究

近年来国内外针对工艺设备对电子工厂洁净室气流组织影响开展相关研究,但均未考虑工艺设备排风的影响。针对是否考虑工艺设备排风时某电子工厂外延工序洁净室流场进行CFD模拟对比分析,发现两者偏差很大。动态下外延工序工艺设备设有排风,工艺设备排风对洁净室速度、压力分布等影响较大,必须考虑工艺设备排风对洁净室气流组织的影响。为了获得准确的工艺设备排风量,对比分析了利用生产系统排风管单个传感器采集的排风量和现场多点测试得到的机台排风量之间的差异,并将两组数据分别作为工艺设备排风量输入条件进行洁净室气流组织仿真模拟,通过仿真与测试数据对比分析,发现采用第二种方法得到的模拟结果与实测数据吻合很好,验证仿真模拟结果的准确性。并得到了动态下外延工序洁净室速度、压力分布等真实气流组织情况。