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1.
Deserts are ideal places to develop ground-mounted large-scale solar photovoltaic (PV) powerstation. Unfortunately, solar energy production, operation, and maintenance are affected bygeomorphological changes caused by surface erosion that may occur after the construction of the solar PVpower station. In order to avoid damage to a solar PV power station in sandy areas, it is necessary toinvestigate the characteristics of wind-sand movement under the interference of solar PV array. The studywas undertaken by measuring sediment transport of different wind directions above shifting dunes andthree observation sites around the PV panels in the Hobq Desert, China. The results showed that the twoparameterexponential function provides better fit for the measured flux density profiles to the near-surfaceof solar PV array. However, the saltation height of sand particles changes with the intersection anglebetween the solar PV array and wind direction exceed 45°. The sediment transport rate above shifting duneswas always the greatest, while that around the test PV panels varied accordingly to the wind direction.Moreover, the aeolian sediment transport on the solar PV array was significantly affected by wind direction.The value of sand inhibition rate ranged from 35.46% to 88.51% at different wind directions. When theintersection angle exceeds 45°, the mean value of sediment transport rate above the solar PV array reducesto 82.58% compared with the shifting dunes. The results of our study expand our understanding of theformation and evolution of aeolian geomorphology at the solar PV footprint. This will facilitate the designand control engineering plans for solar PV array in sandy areas that operate according to the wind regime.  相似文献   
2.
土壤电导率是表征土壤水溶性盐的一个重要指标,可反映土壤盐渍化程度。为了研究高寒草甸退化对土壤电导率的影响,以三江源区未退化高寒草甸和退化高寒草甸为研究对象,系统分析了退化高寒草甸的植被特征和土壤特征与土壤电导率的相互关系。结果表明:高寒草甸退化会对土壤电导率产生显著负影响,且土壤电导率与评价高寒草甸的退化指标植被盖度、地上生物量、土壤有机质、土壤全氮含量表现出一致的变化趋势。因而,认为高寒草甸的退化是会引起土壤电导率的变化,土壤电导率作为土壤盐渍化程度的衡量指标,亦可作为评价草甸退化的客观指标之一。  相似文献   
3.
【目的】土壤盐渍化是限制新疆南部棉花高产的主要因子,准确获取区域尺度土壤剖面盐分信息。【方法】以南疆阿拉尔垦区为研究区,以田间尺度采集的30个不同盐渍化程度棉田的540个样点的0~0.375、0~0.750、0~1.000 m的土壤剖面电导率数据和对应的电磁感应数据为数据源,采用线性模型和非线性模型分别构建了田间尺度和区域尺度的土壤剖面电导率的电磁感应反演模型,并采用缩减建模样本量方法进一步检验了区域尺度模型的可靠性和稳定性。【结果】多元线性回归(MLR)、偏最小二乘回归(PLSR)和主成分回归(PCR)建模方法的田间尺度模型R2在0.88~0.95,而对应的区域尺度模型R2在0.34~0.53。基于随机森林(RF)、神经网络(NN)和支持向量机(SVM)非线性建模方法构建的土壤剖面电导率的区域尺度电磁感应反演模型R2在0.60~0.85,其中RF模型的精度最高。0~0.375、0~0.750、0~1.000 m土壤剖面电导率的RF反演模型R2分别为0.80、0.85和0.84,相较于线性建模方法的区域尺度模型精度有明显的提高。RF区域尺度模型的样本数量由540个缩减到240个,模型精度没有明显变化,表明采用区域尺度模型,可大幅度降低土壤剖面样本采集数量,从而可显著提高采样效率和降低采样成本。【结论】区域尺度下构建土壤剖面电导率反演模型时,随机森林建模方法效果较优,模型预测能力具有较高的可靠性。  相似文献   
4.
谷物联合收获机筛分装置研究现状与发展分析   总被引:3,自引:0,他引:3  
筛分是谷物联合收获作业的关键工序,筛分装置的作业质量直接影响联合收获机的作业性能。现有筛分装置性能可基本满足谷物收获作业要求,但鉴于农业物料的多样性、作业环境的多变且不可控性以及谷物联合收获机的高速作业性,在进行筛分时由于物料喂入量增大和物料含水率的升高,从而产生物料堵塞筛孔、潮湿物料粘附筛体、物料流动性差、筛分效率低等问题。本文以筛体结构和筛体驱动机构为切入点,概述谷物筛分装置的研究现状和研究方法,从不同领域筛分技术的借鉴与互补以及筛分装置高效化、智能化、信息化的发展角度出发,指出谷物筛分装置技术的发展趋势,为我国谷物筛分技术研究和筛分装置的创新设计提供参考。  相似文献   
5.
新疆农村被动式太阳房夏季不同降温控制模式的降温效果   总被引:3,自引:2,他引:1  
冬季供暖性能良好的被动式太阳房,夏季室内普遍存在着过热问题。该文以新疆石河子农村的2栋不同构造的被动式太阳房为研究对象,提出4种不同的降温控制模式。通过夏季降温试验研究,重点讨论了白天热压通风、夜间自然通风、地板辐射供冷等措施对于缓解被动式太阳房夏季过热程度的作用,并在此基础上分析了降温措施对室内热舒适适应性的影响程度。试验结果表明:对于新疆农村没有地下室的被动式太阳房,采用该文提出的热压通风结合夜间通风降温模式,满足80%可接受舒适度要求的时长占比可提升35.04%;耦合地下室的被动式太阳房,依靠合理的通风措施和地板辐射供冷,满足80%可接受舒适度的时长占比达到85.80%,可基本实现夏季降温的目标。  相似文献   
6.
Apolygus lucorum (Meyer-Dür) (Hemiptera: Miridae) tends to feed on young plant tissues. To explore the relationship between stylet probing behaviors of adult A. lucorum and conditions of cotton leaves, we conducted an experiment using electropenetrography (EPG). Behaviors were recorded on four cotton varieties, in relation to thickness and biochemical traits of differently-aged leaves. Cotton leaf age had a significant effect on the probing behavior of A. lucorum but cotton variety did not. One-day-old leaves of A. lucorum received the highest mean number of stylet probes (penetrations) per insect, and longest mean durations per insect of combined stylet probing or its components, cell rupture and ingestion behaviors. All of the leaf traits (thickness and biochemical substances) were similar among these four cotton varieties. Leaf thickness had a significantly negative effect on the same four variables above. Gossypol and tannin also had a negative impact on combined probing duration. Redundancy analysis showed that the four EPG variables were closely related to nutrient substances (amino acids, sugar, and water) while they had the opposite relationship with plant defense substances (gossypol and tannin). On cotton in the seedling stages, A. lucorum fed more readily on the youngest, thinnest leaves in our no-choice EPG experiments. Nutrients and chemical resistance substances determined the probing duration of A. lucorum. Our findings can contribute to better understanding of patterns of feeding and host consumption by A. lucorum, ultimately improving cotton resistance to A. lucorum.  相似文献   
7.
Spatial variations in yield occur in all agricultural fields to some degree. Knowledge of the reasons for these variations, especially temporally stable yield patterns, is needed in order to improve productivity by changing production methods or inputs. This information must be provided in a simple, cost-effective way. This study investigated whether field-scale measurements of penetration resistance (PR) could identify temporally stable yield patterns without complementary measurements of other properties. The PR measurements were also compared with field-scale apparent electrical conductivity (ECa) measurements and correlations between yield and PR and yield and ECa were investigated. Measurements with a newly constructed horizontal penetrometer and a non-invasive proximal electromagnetic induction sensor were carried out in three fields in east-central Sweden. The measurements were made once in each field, apart from one field where PR was measured twice in one season. The sensor measurements were compared with crop yield measured over the course of several years. The horizontal penetrometer was able to identify low-yielding areas in one field. However, single measurements of PR or ECa were insufficient to consistently identify yield variations. Parts of the fields showed more consistent patterns, with stronger correlations between PR, ECa and yield. PR and ECa data were better at explaining yield variations in drier years, but showed diverging patterns in different fields and neither showed a much stronger correlation to yield than the other. In future studies, simultaneous measurement of soil water content is recommended and also PR measurements at a water content drier than field capacity.  相似文献   
8.
The increase in client willingness to pursue surgical procedures, the heightened perceived value of veterinary patients, and the desire to provide comprehensive medical care have driven the recent demand of using an integrative treatment approach in veterinary rehabilitation. Physical therapy following neurologic injury has been the standard of care in human medicine for decades, whereas similar rehabilitation techniques have only recently been adapted and utilized in veterinary medicine. Spinal cord injury is the most common neurologic disease currently addressed by veterinary rehabilitation specialists and will be the primary focus of this review; however, research in other neurologic conditions will also be discussed. Of particular interest, to clients and veterinarians are techniques and modalities used to promote functional recovery after neurologic injury, which can mean the difference between life and death for many veterinary patients.The trend in human neurologic rehabilitation, often regardless of etiology, is a multimodal approach to therapy. Evidence supports faster and improved recoveries in people after neurologic injury using a combination of rehabilitation techniques. Although the primary neurological disorders researched tend to be spinal cord injury, peripheral neuropathies, allodynia, multiple sclerosis, and strokes—many correlations can be made to common veterinary neurological disorders. Such comprehensive protocols entail gait training activities in combination with neuromuscular electrical stimulation and directed exercises. Additionally, pain-relieving and functional benefits are bolstered when acupuncture is used in addition to rehabilitation. Studies, both laboratory and clinical, support the use of acupuncture in the management of neurologic conditions in small animals, specifically in cases of intervertebral disc disease, other myelopathies, and neuropathic pain conditions. Acupuncture’s ability to promote analgesia, stimulate trophic factors, and decrease inflammation, including neuroinflammation, make it an alluring adjunct therapy after neurologic injury.Although there is limited research in veterinary medicine on physical techniques that expedite recovery after neurologic injury, there are sparse publications on clinical veterinary research suggesting the benefits of acupuncture, rehabilitation, and LASER in dogs with intervertebral disk disease. Accordingly, due to the relative lack of evidence-based studies in veterinary neurologic rehabilitation, much of the data available is human or laboratory-animal based, however, evidence supports the utilization of an early, comprehensive treatment protocol for optimal neurologic recovery. The rationale for why an integrative approach is critical will be detailed in this review; in addition, literature on specific physical rehabilitation techniques that have evidence of improved recoveries after neurologic injury, will be addressed.  相似文献   
9.
通过分析营养元素对油松抗旱能力的影响规律,以期为科学施肥提供理论依据。笔者设置S1(常规对照)、S2(清水对照)、S3(N)、S4(NK)、S5(NPK)5个处理,3次重复。结果表明:SOD活性S5在5、6、7、8月分别比S1处理提高了68.66%、64.54%、36.02%、30.03%,差异显著;POD活性S5分别高于S1处理79.96%、117.82%、51.65%、41.28%,差异显著;CAT活性S5在6、8月分别比S1提高了35.86%、33.51%,差异显著;PPO活性S5分别比S1提高92.18%、125.15%、74.95%、57.77%,差异显著;S5处理电导率始终处于最低值,分别比对照(S1)降低40.46%、24.73%、25.99%、55.55%,差异显著。S5对提高水分胁迫下油松幼苗保护酶活性和降低电导率效果最佳。  相似文献   
10.
四端法土壤电导率传感器恒流源设计与试验   总被引:1,自引:0,他引:1  
土壤信息对于指导农业生产有着极为重要的作用,土壤电导率反映了土壤含水量、盐分、粘粒含量和类型等土壤信息,准确获取土壤电导率对于实现农业精细化生产意义重大。在各种土壤电导率测量方法中,四端法因其成本低、精度高、测量快速和操作简便而大量应用于实际测量;恒流源是四端法测量仪器的重要组成部分,其性能直接决定着测量仪器的精度以及测量范围。本文对比了3种恒流源对测量仪器测量性能的影响,发现采用Howland恒流源的四端法测量仪器高电导率测量能力强而低电导率测量范围较小,测量精度最高;采用改进型Howland恒流源的四端法测量仪器低电导率测量范围有所扩大,测量精度良好;采用基于差动放大器的恒流源的电导率仪低电导率测量范围最大,高电导率测量范围较优,测量精度良好。  相似文献   
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