共查询到20条相似文献，搜索用时 15 毫秒
1.
We examined 79 Japanese MNCs’ R&D subsidiaries in the US from the knowledge-based view. We found: (1) subsidiaries’ R&D strategies generally encouraged knowledge flows; (2) subsidiaries’ R&D alliances promoted knowledge flows; (3) R&D subsidiaries with process-oriented incentives promoted vertical knowledge flows; (3) autonomous R&D subsidiaries promoted knowledge flows from the local environments to the subsidiary; (4) R&D subsidiaries with a high level of knowledge flows accumulated a high level of knowledge; and (5) R&D subsidiaries with a high level of accumulated knowledge achieved high overall performance. Our interviews with 30 R&D subsidiaries and 10 parent companies supplement these findings. 相似文献
2.
This work analyses the effect of public subsidies on firms’ investments and investment–cash flow sensitivity in a longitudinal sample of 288 Italian unlisted non-venture capital backed owner-managed new-technology-based firms (NTBFs), observed over a 15-year period from 1994 to 2008. Seventy five of these firms received one or more public subsidies in the observation period. We use an error correction model (ECM) specification and system generalised method of moment (GMM) techniques that take into account the endogeneity of public subsidies. First, we find that the investments of small NTBFs are sensitive to internal cash flows, while those of large NTBFs are not. Receipt of public subsidies by small NTBFs results in an increased investment rate and a reduced investment–cash flow sensitivity, in the immediately following year. We interpret these results as an indication of the relaxation of financial constraints. Moreover, while the increase in the investment rate does not persist in the long run, the dependence of investments on cash flow remains negligible after receipt of the first public subsidy. These results support the view that public subsidies can help small NTBFs in persistently removing the financial constraints that bind their investment activity. 相似文献
3.
This paper deals with the problem of a new delay-dependent robust stability criteria for a class of mixed neutral and Lur’e systems. The system has time-varying uncertainties, interval time-varying delays and sector-bounded nonlinearity. The proposed method is based on Lyapunov method, a delay-dependent criterion for asymptotic stability is established in terms of linear matrix inequality (LMI). Numerical examples show the effectiveness of the proposed method. 相似文献
4.
Jen-Yung Chang Shuo Wang Jeffrey S. Allen Seong Hyuk Lee Suk Tai Chang Young-Ki Choi Craig Friedrich Chang Kyoung Choi 《Biomicrofluidics》2014,8(4)
An electro-osmosis (EOS) diode pumping platform capable of culturing cells in fluidic cellular micro-environments particularly at low volume flow rates has been developed. Diode pumps have been shown to be a viable alternative to mechanically driven pumps. Typically electrokinetic micro-pumps were limited to low-concentration solutions (≤10 mM). In our approach, surface mount diodes were embedded along the sidewalls of a microchannel to rectify externally applied alternating current into pulsed direct current power across the diodes in order to generate EOS flows. This approach has for the first time generated flows at ultra-low flow rates (from 2.0 nl/s to 12.3 nl/s) in aqueous solutions with concentrations greater than 100 mM. The range of flow was generated by changing the electric field strength applied to the diodes from 0.5 Vpp/cm to 10 Vpp/cm. Embedding an additional diode on the upper surface of the enclosed microchannel increased flow rates further. We characterized the diode pump-driven fluidics in terms of intensities and frequencies of electric inputs, pH values of solutions, and solution types. As part of this study, we found that the growth of A549 human lung cancer cells was positively affected in the microfluidic diode pumping system. Though the chemical reaction compromised the fluidic control overtime, the system could be maintained fully functional over a long time if the solution was changed every hour. In conclusion, the advantage of miniature size and ability to accurately control fluids at ultra-low volume flow rates can make this diode pumping system attractive to lab-on-a-chip applications and biomedical engineering in vitro studies. 相似文献
5.
国家尺度上铝的社会流动过程解析 总被引：7，自引：2，他引：5
定性解析金属元素的社会流动过程,是定量化开展其物质流分析和资源流研究的前提。铝是世界上生产量与消费量最大的有色金属,同时也是具有良好再生性能的金属。在大量文献调研和专家访谈的基础上,本文基于金属元素物质流分析的一般性框架,详细解析了铝在国家尺度上的社会流动过程,将其概括为3个“四”:四阶段、四种库和四种流。四阶段包括:生产阶段、加工与制造阶段、使用阶段、报废与再生阶段。四种库包括:矿产资源库、第一和第二阶段产品的暂时性库存、使用阶段的社会累积库、各种含铝废弃物的堆存库(包括弃矿、尾矿、选冶废渣堆存场和垃圾填埋场等)。四种流即正向流、逆向流、废物流、进出口流。以四阶段为依托,重点刻画了四种流的具体过程,为进行定量化的铝物质流分析及相应的能量流、价值流和环境影响分析提供了基础。 相似文献
6.
《Research Policy》2022,51(5):104509
In the global open innovation environment, one of the main characteristics of the knowledge-based economy is to pay more attention to the importance of global knowledge flows. This paper investigates global knowledge flows from the perspective of patent transfers, which can not only reflect the patents' economic value but also explore explicit and tacit knowledge flows comprehensively. This paper begins with the premise that global knowledge flows include the internal absorption of knowledge (IAK), knowledge outflows (KOFs) and knowledge inflows (KIFs) based on a dataset derived from United States Patent and Trademark Office (USPTO) during 2002 and 2016. Then, a global knowledge flow network is constructed by integrating patent transfer analysis and social network analysis. Our results show that more and more inventors and assignees are involved in the global knowledge flow network, China and India's ranking in the list of knowledge creators and users rises rapidly, cross-border knowledge flows will become a new trend; the rapid development of G06F (electric digital data processing), H04L (transmission of digital information) and other technological fields has accelerated the global knowledge flows; at present, the United States is the largest net knowledge inflow participant, the United Kingdom is the largest net knowledge outflow participant; the characteristics of a small-world effect in the cross-border knowledge flow network composed of 35 major participants become increasingly obvious. Our findings have clear policy implications. Establishing a global knowledge flow network is needed in order to promote global knowledge transfers, absorption and sharing. 相似文献
7.
Zhanqiang Zhang Chunxia Dou Dong Yue Bo Zhang Wei Luo 《Journal of The Franklin Institute》2018,355(17):8874-8890
To achieve the frequency restoration (FR) and accurate reactive power sharing (RPS) in islanded microgrids (MGs), an improved P-f droop control is proposed. Firstly, the inverter impedance, whose value is set by the virtual impedance method, is used to minimize the impact of line resistance on powers coupling and RPS. Then, in order to restore the frequency of distributed generations (DGs) to the rated value, the reference is changed for compensating the frequency deviation (FD) caused by loads change. And the fast FR rate is achieved under a large constant k. Besides, in order to eliminate the inaccuracy of RPS caused by voltages difference (VD), the line voltage drop (LVD) is used to compensate the voltage droop characteristics. The use of voltage feedback ensures that the obtained voltage is desired after the LVD compensation. Finally, the simulation in RT-LAB indicates the effectiveness of proposed method in an islanded MG model. 相似文献
8.
University-incubator firm knowledge flows: assessing their impact on incubator firm performance 总被引：2，自引：0，他引：2
Technology incubators are university-based technology initiatives that should facilitate knowledge flows from the university to the incubator firms. We thus investigate the research question of how knowledge actually flows from universities to incubator firms. Moreover, we assess the effect of these knowledge flows on incubator firm-level differential performance. Based on the resource-based view of the firm and the absorptive capacity construct, we advance the overarching hypothesis that knowledge flows should enhance incubator firm performance. Drawing on longitudinal and fine-grained firm-level data of 79 technology ventures incubated between 1998 and 2003 at the Advanced Technology Development Center, a technology incubator sponsored by the Georgia Institute of Technology, we find some support for knowledge flows from universities to incubator firms. Our evidence suggests that incubator firms’ absorptive capacity is an important factor when transforming university knowledge into firm-level competitive advantage. 相似文献
9.
“双一流”背景下,高层次人才流动出现乱象,亟需政府对此进行监管,从而引导人才流动回归学术本源。将前景理论引入演化博弈模型,构建政府与高校针对高层次人才流动的收益感知演化博弈矩阵,对博弈双方的决策行为以及演化结果的稳定性进行分析。研究结果表明,高层次人才非正常流动监管演化博弈存在5个均衡点,但是由于过度自信、风险偏好、认知偏差等因素导致系统难以收敛于稳定点。提出建立政府-公众监管机制、构建高层次人才信息公示平台,以及高校需有长远战略眼光等对策来制约影响因素,从而促使博弈达到均衡稳定点,实现高层次人才的正常合理流动。 相似文献
10.
The micro-determinants of meso-level learning and innovation: evidence from a Chilean wine cluster 总被引：7，自引：0，他引：7
Most analyses of the relationship between spatial clustering and the technological learning of firms have emphasised the influence of the former on the latter, and have focused on intra-cluster learning as the driver of innovative performance. This paper reverses those perspectives. It examines the influence of individual firms’ absorptive capacities on both the functioning of the intra-cluster knowledge system and its interconnection with extra-cluster knowledge. It applies social network analysis to identify different cognitive roles played by cluster firms and the overall structure of the knowledge system of a wine cluster in Chile. The results show that knowledge is not diffused evenly ‘in the air’, but flows within a core group of firms characterised by advanced absorptive capacities. Firms’ different cognitive roles include some—as in the case of technological gatekeepers—that contribute actively to the acquisition, creation and diffusion of knowledge. Others remain cognitively isolated from the cluster, though in some cases strongly linked to extra-cluster knowledge. Possible implications for policy are noted. 相似文献
11.
Fei Hao 《Journal of The Franklin Institute》2010,347(8):1511-1525
The robust absolute stability problem for norm uncertain and structured uncertain discrete Lur’e systems is considered in this paper by using Lyapunov function method. A sufficient condition of absolute stability for discrete Lur’e systems is established in terms of linear matrix inequalities (LMIs) or the equivalent frequency-domain condition. We compare the result with the Popov-like criterion (Tsypkin criterion) and extended strictly positive real (ESPR) lemma. Furthermore, sufficient conditions on absolute stability for discrete Lur’e systems with norm and structured uncertainties are also presented based on linear matrix inequalities. Estimates of the maximum bounds of all admissible perturbations are given by generalized eigenvalue problems. Finally, several numerical examples are worked out to illustrate the efficiency of the main results. 相似文献
12.
This paper presents a method for the evaluation of the tensile strength of composite materials made of a soft matrix with hard inclusions. The tensile strength is calculated as the force per unit area required for the onset of plastic flow in the material. In addition to the tensile strength, the severity of the core deformation and the rate of void formation are also estimated. The results are based on an upper-bound analysis with a two parameter family of velocity fields which accounts for both non-homogeneity of deformation and void formation.The model of the composite and the family of the velocity field used here have already appeared in published articles. Moreover, the application of the present method to estimate the tensile strength in cases when ductile deformation prevails (i.e. when there is no void formation) would lead to the same results as in the previous studies based on the same model and velocity fields.New here is the completeness of the analysis. All possible flow patterns, including for the first time void forming flows, were considered. This made it possible to show that the conditions required to ensure that one or another flow pattern prevails (i.e. those conditions found here and in other articles based on the same model) are not only necessary but also sufficient, at least from a theoretical point of view.The results of this paper have not yet been confirmed experimentally. Although the general trends are in the expected direction, so far no attempt has been made to find the degree of correlation between the theory and the behavior of real materials. 相似文献
13.
论网站信息流整合及其对人流的导引 总被引：4，自引：0，他引：4
网站信息流是互联网信息传递的基本形式和唯一介质，是众多形态“流”中最具影响，并对人流的产生与变化发挥巨大的导引作用。本文以网站信息流的整合为切入点，从信息流受众接受信息的角度出发，将网站信息流对人流的导引视为主动式导引、被动式导引和互动式导引，剖析了与网站信息流导引密切相关的多种人流规律。 相似文献
14.
Tong Binggang 《中国科学院研究生院学报》1998,(2)
１ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｄｅｖｅｌｏｐｍｅｎｔｏｆＣＦＤａｉｍｅｄｎｏｔｏｎｌｙａｔｔｈｅｃａｐａｂｉｌｉｔｙｏｆｃｏｍｐｌｅｘｆｌｏｗｃｏｍｐｕｔａｔｉｏｎｓｗｉｔｈｈｉｇｈａｃｃｕｒａｃｙａｎｄｈｉｇｈｅｆｉｃｉｅｎｃｙ,ｂｕｔａｌｓｏａ... 相似文献
15.
文章主要介绍了利用PSD-BPA潮流计算软件进行县级电网潮流计算的方法、步骤及进行县级电网潮流计算结果优化调整的一些具体措施;并以横县电网为例,介绍了县级电网无功优化结果对县级电网规划建设的重要作用。除此之外,文章还简单的介绍了进行县级电网潮流计算的方法、步骤和进行县级电网规划建设的原则、方法和步骤,以期能为有关部门进行县级电网的无功优化和规划建设提供一定的参考。 相似文献
16.
Janna Tenenbaum-Katan Rami Fishler Barbara Rothen-Rutishauser Josué Sznitman 《Biomicrofluidics》2015,9(1)
At the onset of life in utero, the respiratory system begins as a liquid-filled tubular organ and undergoes significant morphological changes during fetal development towards establishing a respiratory organ optimized for gas exchange. As airspace morphology evolves, respiratory alveolar flows have been hypothesized to exhibit evolving flow patterns. In the present study, we have investigated flow topologies during increasing phases of embryonic life within an anatomically inspired microfluidic device, reproducing real-scale features of fetal airways representative of three distinct phases of in utero gestation. Micro-particle image velocimetry measurements, supported by computational fluid dynamics simulations, reveal distinct respiratory alveolar flow patterns throughout different stages of fetal life. While attached, streamlined flows characterize the shallow structures of premature alveoli indicative of the onset of saccular stage, separated recirculating vortex flows become the signature of developed and extruded alveoli characteristic of the advanced stages of fetal development. To further mimic physiological aspects of the cellular environment of developing airways, our biomimetic devices integrate an alveolar epithelium using the A549 cell line, recreating a confluent monolayer that produces pulmonary surfactant. Overall, our in vitro biomimetic fetal airways model delivers a robust and reliable platform combining key features of alveolar morphology, flow patterns, and physiological aspects of fetal lungs developing in utero. 相似文献
17.
《Journal of The Franklin Institute》2021,358(15):7447-7467
Protection and reliability enactment of electrical systems are important and emerging in power system research. Nowadays, it is very evident that the implementation of an intelligent algorithm is found in the field of substation equipment protection and relaying purposes. Majority of the researches are based on single load connected to a single feeder line and validated using simulation. A hardware based implementation and validation system will be an additional aspects. In this paper, we have discussed an expert system based intelligent relaying scheme by incorporating fuzzy algorithm in microcontroller. Purpose is to control the moving contacts of the breaker part for controlling multiple loads connected to a single feeder line. This paper reports the entire performance of intelligent relaying mechanism only considering stage - I with respect to non-fuzzy based relaying scheme and successfully achieved fastest coordination time after validating it under IEEE 13 Bus system. We have also validated the cascaded fuzzy based system and a non-fuzzy based system using ATMEL microcontroller. 相似文献
18.
This paper presents a simple-to-construct, low dead volume pump capable of generating a wide range of positive and negative pressures for microfluidic applications. The pump generates pressure or vacuum by changing the volume of air confined inside a syringe and is able to generate pressures between -95 and +300 kPa with a resolution as high as 1 Pa. Different from syringe pumps and electrokinetic pumping, which are capable of controlling flow rates only, our pump can be used to generate constant flow rates or constant pressures, which are required for certain applications such as the aspiration of biological cells for biophysical characterization. Compared to syringe pumps, the new pump has almost zero dead volume and does not exhibit pulsatile flows. Additionally, the system does not require electrical power and is cost effective (～$100). To demonstrate the capabilities of the pump, we used it to aspirate osteoblasts (MC3T3-E1 cells) and to determine Young's modulus of the cells, to generate a concentration gradient, and to produce variable-sized droplets in microchannels using hydrodynamic focusing. 相似文献
19.
The objective of perforating the petroleum wells is to maximize well productivity. A good connectivity between the wellbore and formation can lead up to achieve that goal. However, the conventional method of perforation, which basically involves the use of explosive charges, rarely meets the expected well productivity. It is mainly because of the formation of a region of reduced permeability around the perforation tunnel. To offset such and several other shortcomings of present practices, a new technique is required, the highlight of this paper. Described as the ‘perforation by drilling’ (PD), this new technique is examined and compared for its performance with that of another technique, ‘Perforation by Shooting’ (PS). For this, the experimental and numerical results of the PS technique on cylindrical sand samples of varying amounts of strength and porosity are studied. Moreover, in order to achieve a so-called ‘perfect perforation’, results are compared with the ‘Casting technique’. Three different samples were selected for the measurement of fluid flow rate and differential pressure across the perforation using a ‘geotechnical digital system’ (GDS), which is a triaxial testing device. Profiles such as fluid flow rate with a change in differential pressure and pressure build-up data with time, signify that the PD technique can achieve maximum wellbore productivity when compared to the PS technique. Results also indicate that at a 100 kPa differential pressure, the PS, PD and Casting techniques can achieve 0.20, 0.65 and 1.00 mL/s fluid flow rates respectively across a sample. The paper also implements a 1-D time dependent porous media flow model to simulate flow across the perforated cylindrical samples created by the PS, PD and Casting techniques. Results show a good consistency between the experimental and numerical approaches. 相似文献
20.
A focusing-based microfluidic mixer was studied. The micromixer utilizes the focusing process required for cytometry to reduce the diffusion distance of molecules to be mixed in order to facilitate the passive diffusion-controlled mixing process. It was found that both the high flow rate ratio of the sheath flow to the flows to be mixed and the low flow rate of the mixing fluids resulted in the short mixing length required within the microfluidic channel. It was shown that a complete mixing was achieved within a distance of 4 mm in the micromixer for the focused mixing fluids at a flow rate of 2 μl∕min and a flow rate ratio of the sheath flow to the flows to be mixed at 4:1. The mixer described here is simple and can be easily fabricated and controlled. 相似文献