Pinus densiflora var. zhangwuensis grows fast, and its drought and salinity resistance are better than Pinus sylvestris var. mongolica. We compared cold hardiness and mechanisms of cold hardiness between the two speci...Pinus densiflora var. zhangwuensis grows fast, and its drought and salinity resistance are better than Pinus sylvestris var. mongolica. We compared cold hardiness and mechanisms of cold hardiness between the two species, to provide a theoretical basis for promoting and applying P. densiflora var. zhangwuensis in cold regions. A cold stress experiment was carried out on 3-year-old plantlets of P. densiflora var. zhangwuensis and P. sylvestris var. mon- golica after hardening at five temperature regimes, 5, -10, -20, -40, and -60 ℃, respectively. Some indices of needle samples for both species were measured, such as relative conductivity （REL）, maximum photochemical efficiency （Fv/Fm）, malondialdehyde （MDA）, catalase （CAT）, proline （Pro）, soluble sugar （SS）, and stomata density. REL and MDA values of both species after hard- ening had the same trend of increasing, but the trend was opposite in Fv/Fm value with increasing cold stress. Com- pared with P. sylvestris var. mongolica, the P. densiflora var. zhangwuensis had smaller increases in REL and MDA, and a smaller decline in Fv/Fm during cold stress. Com- pared to the control, REL growth of P. densiflora var. zhangwuensis and P. sylvestris var. mongolica at -60 ℃were 0.41 and 0.60, and MDA growth was 29.94 mol g-1 FW and 47.80 mol g-1 FW, and Fv/Fm declines were 0.08 and 0.27. Half-lethal temperatures （LT50） calculated by logistic equation for P. densiflora var. zhangwuensis and P. sylvestris var. mongolica were -58.23 and -50.34 ℃, respectively. These data suggest that cold resistance of P. densiflora var. zhangwuensis is stronger than that of P. sylvestris var. mongolica. Cold-resistance mechanisms of the two species differed. In response to cold stress, P. sylvestris var. mongolica had strong osmotic adjustment ability because of higher Pro and SS content, while P. densiflora var. zhangwuensis had strong antioxidant ability due to stronger CAT activity. Stomata density and diameter of P. densiflora var. zhangwuensis were smalle展开更多
针对传统冲洗系统存在的无法精确检测与控制调节冲洗液电导率等问题,基于API Plan 54泵站智能控制系统进行冲洗液电导率调节试验研究。首先验证了采用氨水作为冲洗液电导率调节介质的可行性,为后续的硬件选型等工作提供理论支持,接着完...针对传统冲洗系统存在的无法精确检测与控制调节冲洗液电导率等问题,基于API Plan 54泵站智能控制系统进行冲洗液电导率调节试验研究。首先验证了采用氨水作为冲洗液电导率调节介质的可行性,为后续的硬件选型等工作提供理论支持,接着完成电导率调节介质浓度与冲洗液电导率关系试验,通过多组试验结果分析出电导率检测与控制调节系统的加药精度。试验表明,电导率检测与控制系统可有效完成冲洗液电导率的调节,验证了该系统的控制精度满足项目应用要求。展开更多
光伏电池的输出特性会随着外界环境的变化而改变,利用最大功率点跟踪(maximum power point tracking,MPPT)技术可有效提高光伏发电系统的效率。针对现有MPPT控制方法的不足,提出了一种基于改进型变步长电导增量法的MPPT控制方法。该方...光伏电池的输出特性会随着外界环境的变化而改变,利用最大功率点跟踪(maximum power point tracking,MPPT)技术可有效提高光伏发电系统的效率。针对现有MPPT控制方法的不足,提出了一种基于改进型变步长电导增量法的MPPT控制方法。该方法采用一种新的步长调整系数,可根据外界环境变化自动调整步长,即使光照剧烈变化时,系统始终保持较大步长运行,克服了传统变步长算法启动速度和光照剧烈变化时动态响应速度慢的问题;同时采用电压闭环控制,提高了系统的整体稳定性。仿真和实验结果证明了该方法的可行性。展开更多
基金supported by the National Forestry Public Welfare Industry Research Project(201004023)Liaoning Agricultural Science and Technology Key Project(2011207002 and2011207004)
文摘Pinus densiflora var. zhangwuensis grows fast, and its drought and salinity resistance are better than Pinus sylvestris var. mongolica. We compared cold hardiness and mechanisms of cold hardiness between the two species, to provide a theoretical basis for promoting and applying P. densiflora var. zhangwuensis in cold regions. A cold stress experiment was carried out on 3-year-old plantlets of P. densiflora var. zhangwuensis and P. sylvestris var. mon- golica after hardening at five temperature regimes, 5, -10, -20, -40, and -60 ℃, respectively. Some indices of needle samples for both species were measured, such as relative conductivity （REL）, maximum photochemical efficiency （Fv/Fm）, malondialdehyde （MDA）, catalase （CAT）, proline （Pro）, soluble sugar （SS）, and stomata density. REL and MDA values of both species after hard- ening had the same trend of increasing, but the trend was opposite in Fv/Fm value with increasing cold stress. Com- pared with P. sylvestris var. mongolica, the P. densiflora var. zhangwuensis had smaller increases in REL and MDA, and a smaller decline in Fv/Fm during cold stress. Com- pared to the control, REL growth of P. densiflora var. zhangwuensis and P. sylvestris var. mongolica at -60 ℃were 0.41 and 0.60, and MDA growth was 29.94 mol g-1 FW and 47.80 mol g-1 FW, and Fv/Fm declines were 0.08 and 0.27. Half-lethal temperatures （LT50） calculated by logistic equation for P. densiflora var. zhangwuensis and P. sylvestris var. mongolica were -58.23 and -50.34 ℃, respectively. These data suggest that cold resistance of P. densiflora var. zhangwuensis is stronger than that of P. sylvestris var. mongolica. Cold-resistance mechanisms of the two species differed. In response to cold stress, P. sylvestris var. mongolica had strong osmotic adjustment ability because of higher Pro and SS content, while P. densiflora var. zhangwuensis had strong antioxidant ability due to stronger CAT activity. Stomata density and diameter of P. densiflora var. zhangwuensis were smalle
文摘针对传统冲洗系统存在的无法精确检测与控制调节冲洗液电导率等问题,基于API Plan 54泵站智能控制系统进行冲洗液电导率调节试验研究。首先验证了采用氨水作为冲洗液电导率调节介质的可行性,为后续的硬件选型等工作提供理论支持,接着完成电导率调节介质浓度与冲洗液电导率关系试验,通过多组试验结果分析出电导率检测与控制调节系统的加药精度。试验表明,电导率检测与控制系统可有效完成冲洗液电导率的调节,验证了该系统的控制精度满足项目应用要求。
文摘光伏电池的输出特性会随着外界环境的变化而改变,利用最大功率点跟踪(maximum power point tracking,MPPT)技术可有效提高光伏发电系统的效率。针对现有MPPT控制方法的不足,提出了一种基于改进型变步长电导增量法的MPPT控制方法。该方法采用一种新的步长调整系数,可根据外界环境变化自动调整步长,即使光照剧烈变化时,系统始终保持较大步长运行,克服了传统变步长算法启动速度和光照剧烈变化时动态响应速度慢的问题;同时采用电压闭环控制,提高了系统的整体稳定性。仿真和实验结果证明了该方法的可行性。
