共查询到20条相似文献，搜索用时 31 毫秒
1.
《Journal of The Franklin Institute》2023,360(7):4572-4596
The purpose of this paper is to present a comprehensive study of a coherent feedback network where the main component consists of two distant double quantum dot (DQD) qubits which are directly coupled to a cavity. This main component has recently been physically realized (van Woerkom et al., Microwave photon-mediated interactions between semiconductor qubits, Physical Review X, 8(4):041018, 2018). The feedback loop is closed by cascading this main component with a beamsplitter. The dynamics of this coherent feedback network is studied from three perspectives. First, an analytic form of the output single-photon state of the network driven by a single-photon state is derived. In contrast to the experimental observations made in the above paper where a laser is used as input, new interesting physical phenomena are revealed by means of single-photon input. Second, excitation probabilities of DQD qubits are computed when the network is driven by a single-photon input state. Finally, if the input is vacuum but one of the two DQD qubits is initialized in its excited state, the explicit expression of the steady-state joint system-field state is derived, which shows that the output single-photon field and the two DQD qubits can form an entangled state if the transition frequencies of two DQD qubits are equal. This analytical expression can be used to interpret experimental results in the existing literature. 相似文献
2.
经济全球化时代,国家间商品流动频繁,商品贸易网络化特征突出,亟需从关系网络的生长逻辑探究全球商品贸易的互动场景与演进机理。本文基于1996—2016年全球商品贸易流量数据,借助社会网络分析方法和ArcGIS可视化工具揭示了全球商品贸易网络的生长过程,运用指数随机图模型分析了全球商品贸易网络生长的动力机制。结果表明：①全球商品贸易网络呈扩张式生长,逐步形成“三核”互联主导的“大三角”空间结构,网络骨架的三大集群凸显。中国主导的集群大幅拓展,美国和德国主导的集群日益收缩。各国家（地区）在网络中的分工明确,网络功能差异显著并表现出不同变化特征。②全球商品贸易网络生长受自组织性、国家（地区）匹配性、国家（地区）集散性等内生动力和外生网络嵌入性等外在推力的共同驱动。其中,互惠关系是自组织性的主要结构,国家（地区）收入水平、市场开放趋同性和制度环境异质性是匹配性的关键因素,经济优势和产业竞争力是集散性的重要基础,殖民历史网络、留学生交流网络、语言同构网络、论文合作网络是重要的外生网络。传统的比较优势理论仍然适用于全球商品贸易网络生长机理的解释,尤其对国家（地区）匹配性和集散性的解释力更强。 相似文献
3.
网络社群结构动态对企业创新绩效的影响研究 《科学学研究》2022,40(4):734-745
基于社会网络理论、资源基础观和成长曲线模型,考察不同技术生命周期阶段下企业在创新网络中的社群内结构动态（群内稳定、群内扩张）和社群间结构动态（群间扩张）对企业创新绩效的影响。运用SDC数据库、USPTO、JPO、EPO以及样本企业所在国家专利数据库,以通信设备领域的联盟企业为样本进行实证研究,结果表明在技术导入期,企业群间扩张对创新绩效有负向影响;在技术成长期,企业群间扩张以及保持群内稳定对创新绩效有正向影响;在技术成熟期,企业群内稳定对创新绩效有正向影响,群内扩张与群间扩张对创新绩效有负向影响。在此基础上,提出不同生命周期阶段企业通过调整创新合作网络以提升企业创新绩效的政策建议。 相似文献
4.
技术创新网络在演化中表现出的高度不稳定严重削弱网络的创新输出,探索其演化动力有助于网络重构、提升网络绩效。文章区分网络关系形成和关系解散过程,综合外生节点属性和内生结构依赖,基于TERGMs（时序指数随机图模型）构建技术创新网络演化动力模型,并从生命周期视角下,对OLED（有机发光二极管显示技术）技术创新网络进行实证研究。实证结果表明：企业的技术创新能力在孕育期和成长期对合作关系形成具有显著积极作用,边共享伙伴在成长期显著积极影响关系形成,度扩展和度共享伙伴则在成熟期和再生期显著负向影响关系建立和关系解散过程。最后借助收敛性诊断和拟合优度检验验证了该模型的有效性。 相似文献
5.
当前对企业选择网络中心位置还是网络中介位置进行产品创新仍存有争论,而同时引入技术战略导向和市场动态性两个调节变量分析两种网络位置对产品创新绩效的权变效应有可能破解这个难题。通过对浙江省208家制造企业的实证研究发现,两种网络位置对产品创新绩效都有正向影响,且企业技术战略导向越高,这种正向效应越显著;市场动态性越高,网络中介位置对产品绩效的正向效应越显著,但市场动态性对网络中心位置与产品创新绩效关系负向调节作用并不显著。研究结论不仅明确了不同网络位置发挥效用的具体情境,也为企业选择合适的网络位置进行产品创新提供了启示。 相似文献
6.
风险投资网络演化与网络形成和网络解散密切相关。本研究利用CVSource数据库构建风险投资网络,从机构属性、二元关系、网络结构等多维度提出影响风险投资网络形成和网络解散的假设变量,采用分离时间指数随机图模型（STERGM）,探索我国风险投资网络的演化动力。研究发现,网络形成和网络解散的基础和演化驱动因子存在差异,网络形成是基于发现潜在伙伴的价值和匹配属性,而网络解散是基于对关系质量和未来价值的预期。具体而言,声誉、地理邻近性、结构嵌入和位置嵌入有利于网络关系的形成,且声誉和结构嵌入有利于网络关系持续;认知临近性和位置嵌入对网络关系解散有显著影响。研究结论有助于揭示风险投资网络演化的动力学机制。 相似文献
7.
This study presents a model for predicting the low-cycle fatigue life of steel reinforcing bars using Artificial Neural Network (ANN). A Radial Basis Function (RBF) artificial neural network topology with two additional hidden layers and four neurons (processing elements) in each of these layers is used. The input parameters for the network are the maximum tensile strain (εs,max) and the strain ratio (R) and the output of the ANN is the number of cycles to fatigue failure (Nf). Low-cycle fatigue tests were conducted by the authors in a previous study for different types of steel reinforcing bars subjected to different strain amplitudes and at different strain ratios. The data resulted from these tests were used to train and test the ANN. It is observed that the ANN prediction of low-cycle fatigue life of steel reinforcing bars is within ±2 cycles of the experimental results for the majority of the test data. A parametric study had been carried out to investigate the effect of maximum strain and strain ratio on the fatigue life of steel reinforcing bars. It is concluded that both the strain ratio and the maximum strain have significant effect on the low-cycle fatigue life of such bars, especially at low values of maximum strain and their effect should be considered in both analysis and design. Other observations and conclusions were also drawn. 相似文献
8.
在新一代信息技术搭建的虚拟集聚空间中,如何打破传统组织边界建立非地理临近网络关系对数字赋能型企业成长具有关键作用,揭示不同虚拟集聚型网络关系对企业成长差异化影响的内在机制具有重要意义。本文聚焦云计算企业,整合网络和制度逻辑视角探讨了虚拟集聚型网络规模、互联性、角色多样性对企业成长的影响。结果表明：虚拟集聚型网络规模促进企业成长,网络互联性与企业成长呈倒U型关系,角色多样性促进企业成长,且制度逻辑差异对网络角色多样性与企业成长的正向关系、网络互联性与企业成长的倒U型关系均具有负向调节作用。该研究结论拓展了制度逻辑理论在虚拟集聚形态中的研究范畴,对数字化时代不同背景企业如何在虚拟集聚中协作共赢具有指导意义。 相似文献
9.
《Information processing & management》2020,57(2):102056
Identifying and extracting user communities is an important step towards understanding social network dynamics from a macro perspective. For this reason, the work in this paper explores various aspects related to the identification of user communities. To date, user community detection methods employ either explicit links between users (link analysis), or users’ topics of interest in posted content (content analysis), or in tandem. Little work has considered temporal evolution when identifying user communities in a way to group together those users who share not only similar topical interests but also similar temporal behavior towards their topics of interest. In this paper, we identify user communities through multimodal feature learning (embeddings). Our core contributions can be enumerated as (a) we propose a new method for learning neural embeddings for users based on their temporal content similarity; (b) we learn user embeddings based on their social network connections (links) through neural graph embeddings; (c) we systematically interpolate temporal content-based embeddings and social link-based embeddings to capture both social network connections and temporal content evolution for representing users, and (d) we systematically evaluate the quality of each embedding type in isolation and also when interpolated together and demonstrate their performance on a Twitter dataset under two different application scenarios, namely news recommendation and user prediction. We find that (1) content-based methods produce higher quality communities compared to link-based methods; (2) methods that consider temporal evolution of content, our proposed method in particular, show better performance compared to their non-temporal counter-parts; (3) communities that are produced when time is explicitly incorporated in user vector representations have higher quality than the ones produced when time is incorporated into a generative process, and finally (4) while link-based methods are weaker than content-based methods, their interpolation with content-based methods leads to improved quality of the identified communities. 相似文献
10.
Young Sik Kang Jinyoung Min Jeoungkun Kim Heeseok Lee 《International Journal of Information Management》2013
Individuals with a positive evaluation of a target system are likely to continue using the system, and this sustained use is likely to result in continued use. This target-oriented perspective has served as a major conceptual framework for understanding users’ behaviors in online contexts. The primary objective of this paper is to address two additional perspectives—alternative- and self-oriented perspectives—for a firmer understanding of continued use in the context of social network sites (SNS). A research model is built by employing regret and self-image congruity to represent these two perspectives. The model also examines the condition under which habits are formed and how this automatic mechanism influences the dynamics of the nomological network between intentions and behaviors. The analysis results of two rounds of surveys for capturing the actual link between intentions and behaviors indicate that regret and self-image congruity can play crucial roles in post-adoption phenomena in the context of SNS. 相似文献
11.
联盟组合为焦点企业及合作伙伴的发展创造了丰富的成长路径,提高了企业的竞争优势。现有研究对联盟构型网络的结构、资源冗余性、路径联系与"网络效应"之间的关系,缺乏系统性、动态性的分析。本文围绕焦点企业,结合社会网络及纵向案例研究方法以大唐移动TD-LTE联盟组合为研究对象;探讨了联盟组合构型网络形成的动因、演化特征和路径;提炼了联盟组合构型网络动态演化框架。研究表明:联盟组合内的资源异质性与构型网络多样化密切相关。随着构型网络的规模扩大、路径依赖的增加,会导致整体网络效率的下降,收益递减。而不同阶段焦点企业的控制治理策略选择、网络的拓展与重构能有效提高联盟组合"网络效应"。 相似文献
12.
This study explores the dynamics of a government sponsored collaboration network concerning the development of solar photovoltaics (PV) technologies in China, and investigates the effect of network evolution on the subsequent innovation performance of network actors. Network structure characteristics and attribute proximity variables are jointly examined through a bibliometric methodology based on scientific publication and patent data. In addressing the evolution of the government sponsored collaboration network, this study has identified that actors are more likely to engage in collaboration with prior partners, partners of direct & indirect partners, and partners with similar attributes. These collaboration patterns, in turn, negatively impact direct ties and network efficiency, and increase the attribute proximity of an actor’s network. On the other hand, the estimation results indicate that direct ties have an inverted U-shaped effect on innovation performance, while indirect ties are found to be positively related to innovation performance. As expected, a positive effect of network efficiency is found on innovation performance. The results of attribute proximity variables suggest geographical proximity is negatively related to innovation performance. Taken together, the collaboration patterns in the government sponsored network might have a negative impact on innovation performance of network actors. The empirical findings extend the network literature that collaboration network matters differently in different research contexts, and it is no longer appropriate to simply assume that collaboration is purely a good thing. As such, special attention should be paid to the network structure and composition in further policy design. 相似文献
13.
This paper aims to further our understanding of how embeddedness affects the research output and impact of scientists. The analysis uses an extensive panel data that allows an analysis of within person variation over time. It explores the simultaneous effects of different dimensions of network embeddedness over time at individual level. These include the establishment of direct ties, the strengths of these ties, as well as the density, structural holes, centrality, and cross-disciplinary links. Results suggest that the network dynamics behind the generation of quality output contrasts dramatically with that of quantity. We find that the relational dimension of scientists matters for quality, but not for output, while cognitive dimensions have the opposite effect, helping output, while being indifferent toward impact. The structural dimension of the network is the only area where there is some degree of convergence between output quantity and quality; here, we find a prevalence for the role of brokerage over cohesion. It concludes by discussing implications for both network research and science policy. 相似文献
14.
Erica R.H. Fuchs 《Research Policy》2010,39(9):1133-1147
This paper explores the role of the state in re-architecting social networks and thereby new technology directions in the United States. It draws on a case study of DARPA's Microsystems Technology Office from 1992 to 2008. Leveraging one of the most radical directorships in DARPA's history, I argue that the perceived “death” of DARPA under Tony Tether was because past analyses, by focusing on the organization's culture and structure, overlooked a set of lasting, informal institutions among DARPA program managers. I find that despite significant changes in the recipients and outcomes of DARPA attentions, these same institutions for directing technology were in place both before and during Tether's directorship. Drawing on these results, I suggest that we must add to technology policy-making a new option—embedded network governance. 相似文献
15.
Some networks are explicit where members make direct connections (e.g. Facebook network), whereas other networks are implicit (e.g. co-citation network) in which an edge between two nodes is inferred using a similarity index. Choosing the right index to infer connections in an implicit/inferred network is important because conclusions can be biased if a network does not represent true relationships. In this study, we compared two indexes: Phi Correlation Coefficient (PCC) and Ochiai Coefficient (Och) based on their sensitivity to the sample size of transactions from where the network is inferred. For demonstration, we used an implicit network, called a comorbidity network, developed from health records of 22.1 million patients. The networks were compared based on their overall topologies and node centralities. Results showed that the network formed using Och was more robust to the sample size than PCC. The network using Och followed a small-world topology irrespective of the sample size whereas the structure of a network using PCC was inconsistent. Regarding node centralities, the betweenness centrality was most affected by the sample size. Our results lead us to recommend Och over PCC. 相似文献
16.
17.
We explore how more exactly copying a blueprint for establishing a franchise network in a new country influences franchising network growth. We test opposing hypotheses using panel data involving the transfer of franchising knowledge to 23 different countries, measuring the degree to which master licensees ‘copy exactly’ knowledge concerning how to grow a network in their country and the effect that their approach has on subsequent network growth. We conclude that a strategy of copying more exactly seems to enhance growth and that the benefits of more exactly replicating knowledge in the 1st year of a local network’s existence persist for several years. Thus, innovation, in this specific context, seems to hinder firm growth. 相似文献
18.
《国际创新研究学报(英文)》2021,5(2):35-55
It is often argued that the core of organizational success is efficient collaboration. Some authors even posit that efficient collaboration is more important to organizational innovation and performance than individual skills or expertise. However, the lack of efficient models to manage collaboration properly is a major constraint for organizations to profit from internal and external collaborative initiatives. Currently, much of the collaboration in organizations occurs through virtual network channels, such as e-mail, Yammer, Jabber, Microsoft Teams, Skype, and Zoom. These are even more important in situations where different time zones and even threats of a pandemic constrain face-to-face human interactions. This work introduces a multidisciplinary heuristic model developed based on project risk management and social network analysis centrality metrics graph-theory to quantitatively measure dynamic organizational collaboration in the project environment. A case study illustrates the proposed model's implementation and application in a real virtual project organizational context. The major benefit of applying this proposed model is that it enables organizations to quantitatively measure different collaborative, organizational, and dynamic behavioral patterns, which can later correlate with organizational outcomes. The model analyzes three collaborative project dimensions: network collaboration cohesion evolution, network collaboration degree evolution, and network team set variability evolution. This provides organizations an innovative approach to understand and manage possible collaborative project risks that may emerge as projects are delivered. Organizations can use the proposed model to identify projects' critical success factors by comparing successful and unsuccessful delivered projects' dynamic behaviors if a substantial number of both project types are analyzed. The proposed model also enables organizations to make decisions with more information regarding the support for changes in observed collaborative patterns as demonstrated by statistical models in general, and linear regressions in particular. Further, the proposed model provides organizations with a completely bias-free data-collection process that eliminates organizational downtime. Finally, applying the proposed model in organizations will reduce or eliminate the risks associated with virtual collaborative dynamics, leading to the optimized use of resources; this will transform organizations to become more lean-oriented and significantly contribute to economic, social, and environmental global sustainability. 相似文献
19.
《Journal of The Franklin Institute》2022,359(4):1655-1676
This paper presents a privacy-preserving average consensus algorithm for a discrete-time network with heterogeneous dynamic nodes in the presence of Gaussian privacy noises. Rényi divergence is used to measure the privacy, and a distributed algorithm is proposed for each node in the network to protect the initial output state and ensure consensus almost surely. The convergence rate of the proposed algorithm relates to the communication topology, dynamics of systems, and decaying rates of privacy noises. Moreover, by increasing neighbors of nodes in the network, the proposed algorithm can strengthen preservation. To demonstrate the theoretical results, a numerical example is carried out on a network of one hundred nodes. 相似文献