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排序方式: 共有1083条查询结果,搜索用时 62 毫秒
1.
对数坐标的形式比普通坐标复杂,在应用时容易出现错误.文章分析了对数坐标的本质,从对数坐标的刻度线、数量级、底数、标目等方面进行了探讨,提出了相应的编排格式建议,给出了相差数个数量级、不同底数时非等分刻度线所对应的实际数值公式,指出了常见的几种错误,以期引起科技期刊编辑同行的重视. 相似文献
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领导行为与企业绩效关系的研究一直倍受学术界关注。本研究将战略柔性(资源柔性和能力柔性)作为中介变量,研究动态环境下变革型领导行为对企业绩效的影响并提出研究假设,通过对北京、上海、广东等地区208家上市企业高管的问卷调查及相对应的企业年报获取研究数据并进行数据检验,验证研究假设。研究结果发现,资源柔性和能力柔性在变革型领导行为与企业绩效的关系中具有完全中介作用;环境动态性显著调节变革型领导行为与资源柔性和能力柔性的关系,但对战略柔性与企业绩效的关系无调节作用。本研究的结果说明,动态环境下变革型领导在推动企业变革的过程,要重视战略柔性的作用,引导企业通过转型来适应动态环境,提升企业绩效。 相似文献
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《Journal of The Franklin Institute》2021,358(17):8993-9022
This paper concerns the indefinite linear quadratic (LQ) optimal control problem for discrete-time singular Markov jump systems (MJSs) with finite and infinite horizon, where the weight matrices for state and control of cost function are all indefinite. Firstly, the indefinite LQ problem for singular MJSs is equivalently transformed into indefinite LQ problem for MJSs under a series of equivalent transformations. Then, the sufficient and necessary condition is proposed for the solvability of finite horizon case, the optimal control and optimal cost value are given, and the resulting optimal closed-loop system is regular, casual. Next, some sufficient and necessary conditions are obtained to ensure the transformed equivalent LQ problem for MJSs to be definite one, which can guarantee the generalized algebraic Riccati equation with Markov jump has a unique semi-positive definite solution. Meanwhile, the optimal control and nonnegative optimal cost value in infinite horizon are acquired, and the resulting optimal closed-loop system is stochastically admissible. Finally, three examples are presented to illustrate the theoretical results. 相似文献
4.
《Journal of The Franklin Institute》2022,359(16):9313-9333
This paper studies the fault monitoring problem of a spacecraft control moment gyro (CMG) in complex environments based on the data-driven method. First, the wavelet denoising method and short-time Fourier transform (STFT) are utilized to preprocess the signal measured by an industrial personal computer (IPC) to obtain the frequency spectrum of each failure mode. Then, a slice residual attention network (SRAN) based on the ResNeXt model, attention mechanism, and random slice idea is proposed, which can fully capture the edge features of images while satisfying the learning efficiency. Furthermore, a set of comparative experiments are carried out to validate the ability of the proposed method, and the performance of SRAN is further verified under different datasets. Finally, based on the confusion matrix and t-SNE dimension reduction technique, the monitoring ability of SRAN for various faults is analyzed. Experimental results show that SRAN processes good fault monitoring capability and ideal robustness and can identify different fault degrees under the real-time fault monitoring scenario. 相似文献
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In this paper, we mainly concentrate on the control issue of a variable length drilling riser under condition of unknown disturbances and output constraint. The studied flexible drilling riser system with variable length, variable tension, variable speed and restricted boundary output is essentially a nonlinear distributed parameter system. For achieving the vibration suppression and ensuring the boundary output within the constrained range, an appropriate control scheme with output signal barrier is put forward by integrating boundary control method, barrier Lyapunov function with finite-dimensional backstepping technique, where disturbance observer is employed for coping with the boundary disturbance. Moreover, the Lyapunov’s synthetic method is applied for the steadiness research of the studied flexible drilling riser system, and the simulations are presented to display the usefulness of proposed control scheme. 相似文献
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STEM教育理念融入小学科学教学既有可行性也有必要性。教师在将STEM教育理念融入小学科学教学实践过程中,可采取以下四环节教学策略:第一,引入生活,创设情境,提出科学探究问题;第二,设定方案,选择材料,制作解决问题工具;第三,小组合作,科学验证,技术检测解决问题;第四,归纳分析,得出结论,联系实际归纳提升。这个过程中,可培养学生的科学素养、工程素养、技术素养和数学素养,进而在综合性的科学课堂教学中提升学生的动手能力和创新思维。 相似文献
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《Journal of The Franklin Institute》2022,359(1):84-103
In this paper, the problems of stochastic finite-time stability and stabilization of discrete-time positive Markov jump systems are investigated. To deal with time-varying delays and switching transition probability (STP), stochastic finite-time stability conditions are established under mode-dependent average dwell time (MDADT) switching signal by developing a stochastic copositive Lyapunov-Krasovskii functional approach. Then a dual-mode dependent output feedback controller is designed, thus stochastic finite-time stabilization is achieved based on linear programming technique. Finally, two examples are given to show the effectiveness of our results. 相似文献
10.
程序设计类课程是计算机专业基础课程,也是非计算机本科的基础选修课程。通过分析语言教学现状,针对传统程序设计课程中学生参与度不高的问题,提出基于项目驱动的团队协作教学模式。课堂教学以网络爬虫系统设计为模拟项目,通过改变语言教学体系,不仅激发了学生学习兴趣,而且提高了学习效果,有效培养了学生的计算思维与综合协作能力,使学生课堂参与度接近90%。 相似文献