共查询到20条相似文献,搜索用时 125 毫秒
1.
2.
钻柱起升系统由直流电机驱动,经过减速器、盘式气动离合器带动滚筒进行起升。应用S7—200PLC及其编程软件、6RA28直流调速器、光电编码器组成闭环,对直流电机参数进行反馈控制。 相似文献
3.
分析了永磁同步电机的数学模型,并在空间电压矢量控制技术下建立了转子磁场定向矢量控制系统模型,利用Simulink进行了仿真实验研究。仿真结果表明,系统实现定子电流和转子永磁磁通解耦,转矩特性好,使PMSM达到与直流电机近似的控制效果。 相似文献
4.
钻柱起升系统由直流电机驱动,经过减速器、盘式气动离合器带动滚筒进行起升。应用S7-200 PLC及其编程软件、6RA28直流调速器、光电编码器组成闭环,对直流电机参数进行反馈控制。 相似文献
5.
随着中国经济的发展,社会投保逐渐成为了社会热点。然而一般社会上的保险模型基于从保险公司的权益出发来考虑投保的利益,针对这种情况主要就是基于投保人的既得权益出发建立了r-p双参数模型保险结构模型,借以弥补。该模型充分考虑到投保人发生意外和公司破产的情况,从支付模型。意外概率模型到双参数模型,树形结构构造了投保人选择投保方案的完整过程。 相似文献
6.
7.
考虑在电枢反应的情况下,建立直流电机机械特性数学模型,利用Matlab软件进行仿真,分析电枢反应对直流电机机械特性的影响,主要分析了电枢电流的变化对电机转速和转矩的影响,对于电机在重载和过载情况下运行具有一定意义。 相似文献
8.
9.
10.
介绍了Hull-White模型的校准方法,得到模型的波动率参数,为三叉树的构建做准备,然后主要研究了如何构建Hull-White模型对应的三叉树的建立过程。 相似文献
11.
This paper aims to identify genuine technological spillovers from multinational firms (MNEs). To this end, we use data on R&D from MNEs to measure spillovers, while most of the existing literature uses output to measure the foreign presence in an industry (what we call output-based spillovers). In line with the existing literature, we distinguish between horizontal spillovers (i.e., intra-industry linkages) and vertical spillovers (i.e., backward—or downstream—and forward—or upstream—inter-industry linkages). Our results show that the three types of technological spillovers from MNEs are positive, with the horizontal spillovers the larger ones, followed by backward spillovers. The effect of forward spillovers is much smaller in magnitude. Moreover, we find that not controlling for industry size (i.e., technological spillovers from all firms in an industry) leads to underestimating both horizontal and backward spillovers from MNEs, and to overestimating forward spillovers from MNEs. Finally, we find that the distinction between technological and output-based spillovers is of great relevance. The size of backward technological spillovers is approximately 44% of the size of output-based backward spillovers, while for horizontal spillovers both types of spillovers are quite similar. Importantly, output-based forward spillovers are negative while technological forward spillovers are positive. 相似文献
12.
本文采用2000~2007年工业企业数据,系统考察了外资企业与我国地区产业集聚之间的互动促进关系,并从企业规模、控制权性质两个维度分析不同外资企业与产业集聚之间互动关系的路径差异。结果发现:外资企业与地区产业集聚之间的互动促进关系主要是外资企业与其前后关联行业集聚之间的互动促进,外资企业与同行业的集聚并未形成相互依赖、相互促进的关系;外商独资企业与其前后向关联行业的集聚均存在互动促进,且外商独资与其后向关联行业的集聚之间形成的互动促进是外资企业与我国产业集聚互动促进的主要路径;中外合资企业仅与其前向关联行业集聚之间形成稳定的互动促进关系。 相似文献
13.
本文针对目前国际生产价值链中出现的模块化生产现象,以典型的模块化行业——汽车行业为例,分析这种新兴的生产方式对制造业后向关联效应的影响。对如何提升国内企业在后向关联中的地位,加强外资的后向关联溢出效应提出政策上的建议,并探讨中国企业制定模块化发展战略的可行性及实施途径。 相似文献
14.
研究了低信噪比强窄带干扰条件下的LFM信号检测技术,提出了基于短时傅里叶变换(STFT)的线性调频(LFM)信号增强技术、基于时频峰值滤波的强窄带干扰抑制技术和基于一维搜索的宽带LFM信号检测技术.试验结果表明,采用以上这些方法在低信噪比强窄带干扰情况下,对于LFM信号具有较高的正确检测概率及参数测量精度. 相似文献
15.
16.
Empirical evidence suggests that labor supply curves are downward sloping at low wage levels, i.e. ‘forward‐falling labor supply’. In contrast, the supply curve is only downward sloping at high wage levels in the canonical labor supply model, i.e. ‘backward‐bending’. This paper derives a labor supply curve with both forward‐falling and backward‐bending segments, or an ‘inverted S‐shape’ by incorporating two elements into a standard utility function: a subsistence level of consumption and a decreasing elasticity of substitution. It is also shown that the subsistence level of consumption plays a key role in determining the shape of the labor supply curve. 相似文献
17.
Kolasa Marcin 《The journal of international trade & economic development》2013,22(1):155-173
This paper examines the existence of externalities associated with foreign direct investment (FDI) in a host country by exploiting firm-level panel data covering the Polish corporate sector. We distinguish between horizontal spillovers (from foreign to domestic firms operating in the same industry) and two types of vertical spillovers: backward (from FDI in downstream industries) and forward spillovers (from FDI in upstream industries). The main findings are as follows. Local firms benefit from foreign presence in the same industry and in downstream industries. The absorptive capacity of domestic firms is highly relevant to the size of spillovers: vertical spillovers are larger for R&D-intensive firms, while firms investing in other (external) types of intangibles benefit more from horizontal spillovers. Competitive pressure facilitates backward spillovers, while market power increases the extent of forward spillovers. Horizontal spillovers are particularly strong in services, while the remaining results, including backward spillovers and the role of absorptive capacity and competition, are mainly driven by manufacturing. Host country equity participation in foreign firms is consistent with higher unconditional productivity spillovers to domestic firms. A number of robustness checks yield results qualitatively similar to those obtained in the baseline specification. 相似文献
18.
甘立双 《中国对外贸易(英文版)》2010,(14)
本文介绍了新疆对外开放的现状,找出了对外开放存在的问题,并且提出了相应的改善对策,目的为了提高新疆的对外开放水平,改变落后的现状,通过对外开放取得更快、更好地发展. 相似文献
19.
协调是供应链管理的核心,本文指出供应链协调常用的三种方法:集中控制、结成伙伴关系及契约,从节点企业自身的角度给出了选择协调模式的流程框图,并运用委托—代理理论对供应链协调做出解释。 相似文献
20.
外资技术溢出吸收能力的衡量指标体系及国际比较 总被引:1,自引:0,他引:1
ZHOU Jian 《国际商务-(对外经济贸易大学学报)》2006,(2)
吸收能力分析的是影响外资技术溢出的东道国因素,本文构建的吸收能力指标体系主要包括宏观经济、自然资源和人力资本三个方面。计算出的指标值表明:领先国的教育指标值都很高,落后国没有显示明显的共同点,意味着影响技术溢出吸收能力的因素是综合性的。 相似文献