分类： 地球科学 >> 地理学 提交时间： 2021-04-30 合作期刊: 《干旱区科学》
摘要： Drought was a severe recurring phenomenon in Iraq over the past two decades due to climate change despite the fact that Iraq has been one of the most water-rich countries in the Middle East in the past. The Iraqi Kurdistan Region (IKR) is located in the north of Iraq, which has also suffered from extreme drought. In this study, the drought severity status in Sulaimaniyah Province, one of four provinces of the IKR, was investigated for the years from 1998 to 2017. Thus, Landsat time series dataset, including 40 images, were downloaded and used in this study. The Normalized Difference Vegetation Index (NDVI) and the Normalized Difference Water Index (NDWI) were utilized as spectral-based drought indices and the Standardized Precipitation Index (SPI) was employed as a meteorological-based drought index, to assess the drought severity and analyse the changes of vegetative cover and water bodies. The study area experienced precipitation deficiency and severe drought in 1999, 2000, 2008, 2009, and 2012. Study findings also revealed a drop in the vegetative cover by 33.3% in the year 2000. Furthermore, the most significant shrinkage in water bodies was observed in the Lake Darbandikhan (LDK), which lost 40.5% of its total surface area in 2009. The statistical analyses revealed that precipitation was significantly positively correlated with the SPI and the surface area of the LDK (correlation coefficients of 0.92 and 0.72, respectively). The relationship between SPI and NDVI-based vegetation cover was positive but not significant. Low precipitation did not always correspond to vegetative drought; the delay of the effect of precipitation on NDVI was one year.
分类： 地球科学 >> 地理学 提交时间： 2021-04-30 合作期刊: 《干旱区科学》
Tahani K BAIT SUWAILAM
Abdulrahim M AL-ISMAILI
Nasser A AL-AZRI
L H Janitha JEEWANTHA
Hemesiri KOTAGAMA
摘要： Seawater greenhouse (SWGH) is a technology established to overcome issues related to open field cultivation in arid areas, such as the high ambient temperature and the shortage of freshwater. It adopts the humidification-dehumidification concept where evaporated moisture from a saline water source is condensed to produce freshwater within the greenhouse body. Various condenser designs are adopted to increase freshwater production in order to meet the irrigation demand. The aim of this study was to experimentally investigate the practicality of using the packed-type direct contact condenser in the SWGH to produce more freshwater at low costs, simple design and high efficiency, and to explore the impact of the manipulating six operational variables (inlet air temperature of the humidifier, air mass flowrate of the humidifier, inlet water temperature of the humidifier, water mass flowrate of the humidifier, inlet water temperature of the dehumidifier and water mass flowrate of the dehumidifier) on freshwater condensation rate. For this purpose, a direct contact condenser was designed and manufactured. Sixty-four full factorial experiments were conducted to study the effect of the six operational variables. Each variable was operated at two levels (high and low flowrate), and each experiment lasted for 10 min and followed by a 30-min waiting time. Results showed that freshwater production varied between 0.257 and 2.590 L for every 10 min. When using Minitab statistical software to investigate the significant variables that contributed to the maximum freshwater production, it was found that the inlet air temperature of the humidifier had the greatest influence, followed by the inlet water temperature of the humidifier; the former had a negative impact while the latter had a positive impact on freshwater production. The response optimizer tool revealed that the optimal combination of variables contributed to maximize freshwater production when all variables were in the high mode and the inlet air temperature of the humidifier was in the low mode. The comparison between the old plastic condenser and the new proposed direct contact condenser showed that the latter can produce 75.9 times more freshwater at the same condenser volume.
分类： 地球科学 >> 地理学 提交时间： 2021-04-30 合作期刊: 《干旱区科学》
Abdulrahim M AL-ISMAILI
Moustafa A FADEL
Hemantha JAYASURIYA
L H Janitha JEEWANTHA
Adel AL-MAHDOURI
Talal AL-SHUKEILI
摘要： This study aimed to explore the potential of developing a novel cooling system combining a greenhouse and an earth-tube heat exchanger (ETHE). In this system, greenhouse air is circulated through the underneath soil mass to use the deep-soil cooling effect. This was achieved through the following steps. First, soil temperature profile inside and outside the cultivated greenhouse was monitored for almost one year to study the possibility of using deep-soil coldness for cooling the greenhouse air. Second, a prototype ETHE was built to practically investigate the potential reduction in air temperature as the air flows inside the deep earth pipes. Third, a prototype greenhouse was erected to study the ETHE concept. Results from the first experiment revealed that soil temperature at a soil depth of 2.5 m inside the greenhouse offers good conditions to bury the ETHE. The soil temperature at this soil depth was below the maximum temperature (32°C) that most greenhouse crops can withstand. Results from the prototype ETHE showed a slight reduction in air temperature as it passed through the pipes. From the prototype of the integrated greenhouse and ETHE system, reduction in air temperature was observed as the air passed through the ETHE pipes. At night, the air was heated up across the ETHE pipes, indicating that the ETHE was working as a heater. We concluded from this study that greenhouses in arid climates can be cooled using the ETHE concept which would save a large amount of water that would otherwise be consumed in the evaporative coolers. Further investigations are highly encouraged.
分类： 地球科学 >> 地理学 提交时间： 2021-04-30 合作期刊: 《干旱区科学》
摘要： High temperature and humidity can be controlled in greenhouses by using mechanical refrigeration cooling system such as air conditioner (AC) in warm and humid regions. This study aims to evaluate the techno-financial aspects of the AC-cooled greenhouse as compared to the evaporative cooled (EV-cooled) greenhouse in winter and summer seasons. Two quonset single-span prototype greenhouses were built in the Agriculture Experiment Station of Sultan Qaboos University, Oman, with dimensions of 6.0 m long and 3.0 m wide. The AC-cooled greenhouse was covered by a rockwool insulated polyethylene plastic sheet and light emitting diodes (LED) lights were used as a source of light, while the EV-cooled greenhouse was covered by a transparent polyethylene sheet and sunlight was used as light source. Three cultivars of high-value lettuce were grown for experimentation. To evaluate the technical efficiency of greenhouse performance, we conducted measures on land use efficiency (LUE), water use efficiency (WUE), gross water use efficiency (GWUE) and energy use efficiency (EUE). Financial analysis was conducted to compare the profitability of both greenhouses. The results showed that the LUE in winter were 10.10 and 14.50 kg/m2 for the AC- and EV-cooled greenhouses, respectively. However, the values reduced near to 6.80 kg/m2 in both greenhouses in summer. The WUE of the AC-cooled greenhouse was higher than that of the EV-cooled greenhouse by 3.8% in winter and 26.8% in summer. The GWUE was used to measure the total yield to the total greenhouse water consumption including irrigation and cooling water; it was higher in the AC-cooled greenhouse than in the EV-cooled greenhouse in both summer and winter seasons by almost 98.0%–99.4%. The EUE in the EV-cooled greenhouse was higher in both seasons. Financial analysis showed that in winter, gross return, net return and benefit-to-cost ratio were better in the EV-cooled greenhouse, while in summer, those were higher in the AC-cooled greenhouse. The values of internal rate of return in the AC- and EV-cooled greenhouses were 63.4% and 129.3%, respectively. In both greenhouses, lettuce investment was highly sensitive to changes in price, yield and energy cost. The financial performance of the AC-cooled greenhouse in summer was better than that of the EV-cooled greenhouse and the pattern was opposite in winter. Finally, more studies on the optimum LED light intensity for any particular crop have to be conducted over different growing seasons in order to enhance the yield quantity and quality of crop.
分类： 地球科学 >> 地理学 提交时间： 2021-04-30 合作期刊: 《干旱区科学》
摘要： Groundwater forms the main freshwater supply in arid and semi-arid areas, and contamination of this precious resource is complicated by the slow rate of recharge in these areas. Nitrate contamination of groundwater is a global water quality problem, as it entails threat to human health as well as aquatic ecosystems. Source identification of contamination is the cornerstone and a prerequisite for any effective management program of water quality. Stable isotope composition of the dissolved nitrate (δ15N-NO3– and δ18O-NO3–) has been applied to identify NO3– sources and the main transformation processes in the upper aquifer system (A1/2, A4, and B2/A7 aquifers) in the Wadi Shueib catchment area, Jordan. Moreover, the stable isotope compositions of the groundwater (δ2H-H2O and δ18O-H2O) in conjunction with the groundwater hydrochemistry were integrated to investigate the origin and evolution of the groundwater. Results revealed that groundwater in the study area is fresh and hard-very hard water, and mainly a Ca-Mg-Cl type. NO3– concentration was in the range of 7.0–74.0 mg/L with an average of 37.0 mg/L. Most of the samples showed concentration higher than the natural background concentration of NO3– (5.0–10.0 mg/L). The δ2H-H2O and δ18O-H2O values indicated that the groundwater is meteoric, and of Mediterranean origin, with a strong evaporation effect. The δ15N-NO3– values ranged between 6.0‰ and 11.3‰ with an average of 8.7‰, and the δ18O-NO3– values ranged between 1.6‰ and 5.9‰ with an average of 3.4‰. These values are in conformity with the stable isotope composition of nitrate derived the nitrification of wastewater/manure, and soil NH4. Nitrification and denitrification are the main transformation processes affecting nitrogen species. Statistical analysis revealed no significant differences in the δ2H-H2O and δ18O-H2O values, and δ15N-NO3– and δ18O-NO3– values for the three aquifers (A1/2, A4, and B2/A7), indicating that the groundwater of these aquifers has the same origin, and a common source of pollution.
分类： 地球科学 >> 地理学 提交时间： 2021-04-30 合作期刊: 《干旱区科学》
摘要： Snow cover is an important water source for vegetation growth in arid and semi-arid areas, and grassland phenology provides valuable information on the response of terrestrial ecosystems to climate change. The Mongolian Plateau features both abundant snow cover resources and typical grassland ecosystems. In recent years, with the intensification of global climate change, the snow cover on the Mongolian Plateau has changed correspondingly, with resulting effects on vegetation growth. In this study, using MOD10A1 snow cover data and MOD13A1 Normalized Difference Vegetation Index (NDVI) data combined with remote sensing (RS) and geographic information system (GIS) techniques, we analyzed the spatiotemporal changes in snow cover and grassland phenology on the Mongolian Plateau from 2001 to 2018. The correlation analysis and grey relation analysis were used to determine the influence of snow cover parameters (snow cover fraction (SCF), snow cover duration (SCD), snow cover onset date (SCOD), and snow cover end date (SCED)) on different types of grassland vegetation. The results showed wide snow cover areas, an early start time, a late end time, and a long duration of snow cover over the northern Mongolian Plateau. Additionally, a late start, an early end, and a short duration were observed for grassland phenology, but the southern area showed the opposite trend. The SCF decreased at an annual rate of 0.33%. The SCD was shortened at an annual rate of 0.57 d. The SCOD and SCED in more than half of the study area advanced at annual rates of 5.33 and 5.74 DOY (day of year), respectively. For grassland phenology, the start of the growing season (SOS) advanced at an annual rate of 0.03 DOY, the end of the growing season (EOS) was delayed at an annual rate of 0.14 DOY, and the length of the growing season (LOS) was prolonged at an annual rate of 0.17 d. The SCF, SCD, and SCED in the snow season were significantly positively correlated with the SOS and negatively correlated with the EOS and LOS. The SCOD was significantly negatively correlated with the SOS and positively correlated with the EOS and LOS. The SCD and SCF can directly affect the SOS of grassland vegetation, while the EOS and LOS were obviously influenced by the SCOD and SCED. This study provides a scientific basis for exploring the response trends of alpine vegetation to global climate change.
分类： 地球科学 >> 地理学 提交时间： 2021-04-30 合作期刊: 《干旱区科学》
摘要： Snow avalanches are a common natural hazard in many countries with seasonally snow-covered mountains. The avalanche hazard varies with snow avalanche type in different snow climate regions and at different times. The ability to understand the characteristics of avalanche activity and hazards of different snow avalanche types is a prerequisite for improving avalanche disaster management in the mid-altitude region of the Central Tianshan Mountains. In this study, we collected data related to avalanche, snowpack, and meteorology during four snow seasons (from 2015 to 2019), and analysed the characteristics and hazards of different types of avalanches. The snow climate of the mid-altitude region of the Central Tianshan Mountains was examined using a snow climate classification scheme, and the results showed that the mountain range has a continental snow climate. To quantify the hazards of different types of avalanches and describe their situation over time in the continental snow climate region, this study used the avalanche hazard degree to assess the hazards of four types of avalanches, i.e., full-depth dry snow avalanches, full-depth wet snow avalanches, surface-layer dry snow avalanches, and surface-layer wet snow avalanches. The results indicated that surface-layer dry snow avalanches were characterized by large sizes and high release frequencies, which made them having the highest avalanche hazard degree in the Central Tianshan Mountains with a continental snow climate. The overall avalanche hazard showed a single peak pattern over time during the snow season, and the greatest hazard occurred in the second half of February when the snowpack was deep and the temperature increased. This study can help the disaster and emergency management departments rationally arrange avalanche relief resources and develop avalanche prevention strategies.
分类： 心理学 >> 心理学其他学科 提交时间： 2021-04-30
摘要： 审美对象特有的刺激属性会唤起观赏者特定的情绪或情感反应。个体在欣赏自然、艺术品和其他人类作品时会产生审美愉悦体验。审美愉悦-兴趣模型（PIA）认为，审美愉悦体验包含审美过程中自动化加工阶段的审美愉悦和控制加工阶段的审美兴趣。近年来，神经美学研究表明，负责愉悦和奖赏的眶额叶皮层在审美过程中广泛激活,是自动化加工阶段初级审美愉悦奖赏的神经基础，而审美过程中纹状体亚回路中不同的连接和功能作用与两个阶段中审美愉悦的产生都有关联；上述结果支持了审美愉悦-兴趣模型。但审美高峰体验时默认模式网络（DMN）相关脑区的激活和负责控制与理性思维的外侧前额叶皮层等脑区的失活，提示在PIA模型强调的自动化加工审美愉悦和控制加工阶段审美兴趣之上，还有整合升华阶段的审美沉浸愉悦，PIA模型需得到进一步的扩展。未来研究应进一步检验审美愉悦认知加工模型及神经机制，探索审美对创造力的影响机制和神经基础，探讨不同审美经验愉悦机制的异同。
分类： 心理学 >> 心理统计 提交时间： 2021-04-30
摘要： 追踪研究当中，交叉滞后模型可以探究多变量之间往复式影响，潜增长模型可以探究个体增长趋势。对两类模型进行整合，例如同时关注往复式影响与个体增长趋势，同时可以定义测量误差、随机截距等变异成分，衍生出随机截距交叉滞后模型、特质-状态-误差模型、自回归潜增长模型、结构化残差潜增长模型等。以交叉滞后模型和潜增长模型分别作为基础模型，从个体间/个体内变异分解的角度对上述各类模型梳理，整合出此类模型的分析框架，并拓展建立“因子结构化潜增长模型(factor latent curve model with structured reciprocals)”作为统合框架。通过实证研究(早期儿童的追踪研究-幼儿园版，ECLS-K)，建立21049名儿童的阅读和数学能力的往复式影响与增长趋势。研究发现，分离了稳定特质的模型拟合最优。研究也对模型建模思路和模型选择提供了建议。
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