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151.
本文以豚鼠离体心房肌为标本,研究了不同剂量蛇床子素对心房肌生理特性及对窦房结自律性的影响。结果表明:蛇床子素明显抑制左房肌收缩力和BaCl_2诱发的自律性,抑制右房肌自发收缩力和频率;并延长功能性不应期。上述作用均呈一定的浓度依赖关系;大剂量时,亦能降低心房肌的兴奋性。说明蛇床子素的抗心律失常作用与其降低心肌自律性及兴奋性,延长心肌不应期有关。 相似文献
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153.
平流层通信是指利用位于平流层的高空平台电台代替卫星作为基站的通信。文章基于平流层通信的特点及发展现状,介绍了平流层通信在交通运输行业中的用途,阐述了平流层通信存在的平台搭载、频谱分配、可靠性方面的问题,并提出了相应的解决措施及建议。 相似文献
154.
简单介绍了级联式高压变频器的工作原理.在分析多载波控制算法和阶梯波控制算法的基础上,提出了一种新型优化控制算法,能降低输出谐波含量和开关损耗,且易于实现调压调频控制.最后用MATLAB软件进行了仿真分析,结果表明该新型控制算法是可行的. 相似文献
155.
J. M. Hills D. Alcock T. Higham H. Kirkman M. Le Tissier C. Pagdilao 《Coastal management》2013,41(3):323-337
Development of awareness and capacity is a central component to the delivery of ICM and spans from local communities to national-level politicians. Education and training activities associated with ICM must be extremely varied to match both the existing capacity and role that the stakeholders play within the process of ICM. Consequently, there cannot be considered any effective “generic” ICM training; training must be tailored to match the requirements of target groups. The transfer and uptake of good-practice thus becomes an important aspect of quality enhancement in ICM capacity development. Six case studies from the Asia-Pacific region are presented that show diverse and innovative examples of good practice. A comparative analysis of these case studies is carried out in terms of institutional level of impact. In addition a generic systems-based evaluation framework is used to determine the extent to which the training impacts upon ICM implementation indicators. It is concluded that the exchange, transfer, and translation to local conditions of appropriate good practice in ICM capacity development can be an important element in enhancing the impact of ICM programs on the coastal environments and societies. Furthermore, there appears to be a positive link between the involvement of national/state/regional stakeholders in capacity-building initiatives and impacting a wider variety of indicators of ICM delivery. 相似文献
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157.
Surasak Phoemsapthawee Marc Le Boulluec Jean-Marc Laurens Fran ois Deniset 《船舶与海洋工程学报》2013,12(1):112-121
Underwater gliders are recent innovative types of autonomous underwater vehicles (AUVs) used in ocean exploration and observation. They adjust their buoyancy to dive and to return to the ocean surface. During the change of altitude, they use the hydrodynamic forces developed by their wings to move forward. Their flights are controlled by changing the position of their centers of gravity and their buoyancy to adjust their trim and heel angles. For better flight control, the understanding of the hydrodynamic behavior and the flight mechanics of the underwater glider is necessary. A 6-DOF motion simulator is coupled with an unsteady potential flow model for this purpose. In some specific cases, the numerical study demonstrates that an inappropriate stabilizer dimension can cause counter-steering behavior. The simulator can be used to improve the automatic flight control. It can also be used for the hydrodynamic design optimization of the devices. 相似文献
158.
Secure storage yard is one of the optimal core goals of container transportation;thus,making the necessary storage arrangements has become the most crucial part of the container terminal management systems(CTMS).This paper investigates a random hybrid stacking algorithm(RHSA) for outbound containers that randomly enter the yard.In the first stage of RHSA,the distribution among blocks was analyzed with respect to the utilization ratio.In the second stage,the optimization of bay configuration was carried out by using the hybrid genetic algorithm.Moreover,an experiment was performed to test the RHSA.The results show that the explored algorithm is useful to increase the efficiency. 相似文献
159.
烟草霉变预测尚没有有效的方法。为实时预测仓储烟草的霉变程度,选取仓储环境的温湿度和烟草的自身含水量参数作为神经网络的输入层,烟草霉变度作为输出层,建立BP神经网络烟草霉变预测模型。选取78组实测数据作为训练样本对预测模型进行训练,得出了神经网络的阈值和权值。利用14组预测样本针对该预测模型进行了仿真,并进行了线性回归分析。结果表明,建立的烟草霉变预测模型具有较高的预测精度,预测值和实际值的偏差在[-0.028,0.033]之间,相对误差绝对值的平均值为0.0019。最后,在基于嵌入式ARM+Linux+Web的某公司烟草仓库智能监测系统中,实现了烟草霉变实时预测功能,取得了较好的效果。 相似文献
160.
我国地域幅员辽阔,公路在施工的过程中遇到特殊土质的情况非常普遍。所以,深入分析特殊路基的处理技术对于公路施工而言具有非常重要的意义。鉴于此,对公路施工过程中盐渍土路基的处理技术展开分析,旨在提高我国公路在该种特殊土质段的施工质量。 相似文献