Intensification of the Banana Drying Processes by Using EFL Electromagnetic Waves

Drying of the banana in the hot water has a negative impact on the quality of the product and drying effect. The purposes of this study are increasing the drying rate, using the relatively low temperature to improve the quality (40℃, 50℃ and 60℃) and investigate the use of electromagnetic waves to increase the drying speed. Therefore, experiments are performed using 5 kHz,10 kHz and 15 kHz low frequency electromagnetic waves in the air velocity values of 0.5 m/s, 1 m/s, 1.5 m/s and 2 m/s and 40℃, 50℃, 60℃ centigrade degrees of air blast in a special compartment. Mathematical model of the drying process has been created as using the electrical circuits methods and experimental results. As a result, a simple equation describing the drying process has been obtained. Nonlinear expression of the diffusion coefficient for a different situation in this equation has been identified for the first time. The obtained theoretical results and experimental results have been provided a good agreement. This study is considered to be useful for all studies in the drying area.

1980~2019年成都夏季极端高温事件与其干湿热的时空分布特征

基于1980~2019年成都14个国家气象观测站的逐日气温、气压和相对湿度等数据,统计5类极端高温指标分析成都夏季极端高温的变化,并将成都夏季极端高温分为极端干热型和极端湿热型,利用经验正交函数和傅里叶分解等方法对比分析两者的时空分布特征。结果表明:1980~2019年成都夏季极端高温主要呈西北少、东南多,由西北向东南递增的空间分布;极端高温的强度、频次和持续性在空间分布上有一定差异,成都的西北部和中西部虽有高温天气出现但不易形成持续性的热浪,西部和北部的高温天气更易以持续性的热浪发生,东部和南部则是较强高温热浪的频发区;40年里成都夏季极端高温呈增长趋势并多出现在7月和8月,2006年和2016年为成都夏季极端高温较强的年份。同时,成都夏季的极端高温以极端湿热型为主,且呈增长趋势;过去40年成都极端湿热的增幅整体大于极端干热;极端干热存在2种模态的空间分布型,分别为全区一致型和纬向“三极子”型,相应的时间系数分别在90年代中期和2000年以后出现年际和年代际变化特征;极端湿热主要呈现全区一致的变化特征,对应的时间系数呈增长趋势并有明显的年际和年代际变化特征。

A Well-Balanced Numerical Model for the Simulation of Long Waves over Complex Domains

This paper presents a well-balanced two-dimensional (2D) finite volume model to simulate the propagation, runup and rundown of long wave. Non-staggered grid is adopted to discretize the governing equation and the intercell flux is computed using a central upwind scheme, which is a Riemann-problem-solver-free method for hyperbolic conservation laws. The nonnegative reconstruction method for water depth is implemented in the present model to treat the appearance of wet/dry fronts, and the friction term is solved by a semi-implicit scheme to ensure the stability of the model. The Euler method is applied to update flow variable to the new time level. The model is verified against two experimental cases and good agreements are observed between numerical results and observed data.

Theoretical Modeling and Experimental Analysis of Drying Process in Electromagnetic Field

The effects of electromagnetic waves in drying processes of solid materials are investigated theoretically and experimentally. Modified model of mass transfer being constituted by the effect of electromagnetic waves which have different frequency has been obtained. Modeling of the drying process with a two-port electric circuit for the determination of diffusion coefficients is designed. The frequency limits of electromagnetic wave which will be able to hasten the drying process are determined. The effects of the electromagnetic wave in the potato slice drying process by the influence of different frequencies and temperatures are experimentally examined. The results obtained are compared with theoretical calculations. Moisture concentration curves in drying process have been commented by drawing. Theoretical and experimental results which have been obtained are identified as a well adaptation.

Influence of environmental factors on land-surface water and heat exchange during dry and wet periods in the growing season of semiarid grassland on the Loess Plateau

On the basis of information from the project ＂Land-surface Processes and their Experimental Study on the Chinese Loess Plateau＂, we analyzed differences in land-surface water and heat processes during the main dry and wet periods of the semiarid grassland growing season in Yuzhong County, as well as the influences of these environmental factors. Studies have shown that there are significant differences in changes of land-surface temperature and humidity during dry and wet periods. Daily average normalized temperature has an overall vertical distribution of ＂forward tilting＂ and ＂backward tilting＂ during dry and wet periods, respectively. During the dry period, shallow soil above 20-cm depth is the active temperature layer. The heat transfer rate in soil is obviously different during dry and wet periods. During the dry period, the ratio of sensible heat flux to net radiation （H/Rn） and the value of latent heat flux to net radiation （LE/Rn） have a linear relationship with 5-cm soil temperature; during the wet period, these have a nonlinear relationship with 5-cm soil temperature, and soil temperature of 16℃ is the critical temperature for changes in the land-surface water and heat exchange trend on a daily scale. During the dry period, H/Rn and LE/Rn have a linear relationship with soil water content. During the wet period, these have a nonlinear relationship with 5-cm soil water content, and 0.21 m^3 m^-3 is the critical point for changes in the land-surface water and heat exchange trend at daily scale. During the dry period, for vapor pressure deficit less than 0.7 kPa, H/Rn rises with increased vapor pressure deficit, whereas LEIRn decreases with that increase. When that deficit is greater than 0.7 kPa, both H/Rn and LE/Rn tend to be constant. During the wet period, H/Rn increases with the vapor pressure deficit, whereas LE/Rn decreases. The above characteristics directly reflect the effect of differences in land-surface environmental factors during land-surface water and heat exchange processes, and indirectly reflect the influences of cloud precipitation processes on those processes.

中国夏季干湿型热浪天气时空分布及环境舒适度评价

基于中国气象局对热浪天气的定义并参考地理分区和热浪日湿度分级标准,定义连续3 d以上地面最高气温≥35℃的天气过程为热浪,选取1960-2018年476个地面气象站观测数据研究中国夏季干热型和湿热型热浪日数的时空分布特征及其变化趋势。结果表明,中国夏季热浪日数除新疆外呈现东南高、西北低的空间分布格局,江南地区夏季热浪发生日数最多(年均15 d)。温湿指数和人体舒适度指数评价结果表明江淮地区热浪天气期间环境舒适度最差,热浪天气对人体的不利影响更显著。相对于内陆地区,沿海地区因海风影响午后气温显著降低,有利于缓解热浪天气的影响,因而沿海站点夏季热浪日数比邻近的内陆站点偏少。除黄淮地区外中国大多数站点热浪日数均呈现增加趋势,江苏、浙江沿海、广东、重庆、海南、新疆及广西东部热浪日数增加趋势显著(1~5 d·(10 a)^(-1),α=0.05);中国东部和东南沿海湿热型热浪增加趋势显著,增幅达1~5 d·(10 a)^(-1);浙江、江西北部、甘肃、新疆等地区干热型热浪日数显著增加(α=0.01)。1990年以来全国夏季热浪天气发生更为频繁;其中2000-2009年间干热型热浪日数偏多,而2010年之后强湿热型热浪日所占比例增加。

Maize Seeds Submitted to Thermotherapy and Analyzed by Dynamic Speckle

The quality of the seeds used for sowing is fundamental for a high productivity and quality of the crop. Therefore, eradicating pathogens is essential for the plant to develop in the best possible way. The eradication of those pathogens can be accomplished by means of treatments that consist of the application of substances to the seeds or by performing physical procedures. Thermotherapy is a physical treatment, in which the seed is exposed to a given thermal energy, such as heated air or steam, and can be highly efficient for controlling those pathogens, in addition to reducing environmental damage and costs. The present work aimed to evaluate the efficiency of thermotherapy in two ways： wet heat （water） and dry heat （water vapor）, both at 60 °C, alternating the exposure time to the thermal sources. The treatment with humid heat with a time of exposure of 5 min was the most efficient, since it presented higher germination percentages （83%） and less occurrence of Fusarium sp. （33%）. It was observed that the most efficient thermotherapy is in the control of Fusarium, the most aggressive is for the quality of the seed. The quality of the treatments was evaluated through standard methodologies, according to the rules for seed analysis, such as germination and sanitation tests. Biospeckle laser was used to identify the microbial activity in these seeds, through activity maps generated by laser speckle contrast analysis （LASCA） processing. In this way, the research involving thermotherapy can be done by varying the temperature and the time of exposure to obtain values that considerably reduce the pathogenic agents and preserve the quality, in order to maintain the values of germination and vigor acceptable for commercialization.

热浪背景下城市树木降温效应的变化研究

为探究热浪对城市树木降温能力的影响机制,基于遥感技术计算城市树木降温效率(CE),分析干热浪与湿热浪环境下CE的变化情况。结果表明:西安市和运城市频发干热浪,北京市和襄阳市频发湿热浪,且干热浪的发生频次高、持续时间长;发生干热浪时,西安市、运城市日间CE升高,而发生湿热浪时,北京市、襄阳市日间CE下降;热浪环境下,干热浪频发的城市日间CE较高,而非热浪环境下,湿热浪频发的城市日间CE略高,总体来看,西安市树木降温能力最强;不同城市日间CE对气候条件的响应存在差异,当相对湿度增加时,城市日间CE均减小,当最高气温升高时,西安市和运城市日间CE增加,而北京市和襄阳市日间CE减小;在任何环境下,城市夜间CE差异微弱,且远远小于日间CE。研究结果对于缓解热浪灾害、保护生态系统具有重要意义。

白光“消痈法”辨证分型治疗胃溃疡

白光教授认为胃溃疡是肝郁、食滞、痰湿、血瘀等诸邪化火成痈,宜以痈论治。活动期清热散火消痈;愈合期和瘢痕期养阴益气活血。白光教授将活动期分为五种证型:肝郁化火化肝煎合左金丸,食滞化火用保和丸,痰湿热壅黄连温胆汤,血瘀积热失笑散合血府逐瘀汤,寒热错杂半夏泻心汤合柴胡桂枝干姜汤;愈合期和瘢痕期百合乌药汤,注重保护胃气和预防调护。附病案二例。

长江经济带高温热浪演化特征及人口暴露风险研究

在全球变暖的背景下,高温热浪发生的频率、强度、持续时间不断增加,严重威胁人口健康与社会经济发展,如何判别高温热浪的频发地带,明确潜在的人口高温暴露风险已成为学术界关注的热点。利用气象站点数据、人口统计数据,采用高温热浪指数衡量高温热浪严重程度,并结合湿球黑球温度界定的高温热浪天数及人口普查数据构建人口高温暴露风险模型,在县域尺度上揭示1964~2021年长江经济带高温热浪和人口高温暴露风险的时空演化特征,并对风险进行归因,结果表明:(1)长江经济带累积高温热浪指数整体呈现先减少后大幅度增加的趋势,在空间上呈现出从东南向西北地区逐渐递减的特征,并具有明显的空间集聚性。(2)近60年间长江经济带人口高温暴露风险增加了96.2%,空间分布格局为“一低三高”,即西部地区低,成渝城市群、长江经济带中游及下游核心地带高。人口高温暴露风险集聚模式主要呈现整体集聚化,局部以高暴露风险区县集聚和低暴露风险区县集聚为主的空间特征。(3)人口因子和气候因子对人口高温暴露风险变化起关键作用,且在2000年后,气候因子的作用逐渐加强,贡献率由50%左右增至80%左右。从区域尺度上看,人口因子、气候因子分别对下游地区、中游地区高温暴露风险变化的贡献率最大。