The Experts below are selected from a list of 150 Experts worldwide ranked by ideXlab platform
Zhi-li Zhang - One of the best experts on this subject based on the ideXlab platform.
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Uncovering the nucleus of a massive Reciprocal Network
World Wide Web, 2019Co-Authors: Braulio Dumba, Zhi-li ZhangAbstract:Google+ is a directed online social Network where nodes have either Reciprocal (bidirectional) edges or parasocial (one-way) edges. As Reciprocal edges play an important role in the structural properties, formation and evolution of online social Networks, we study the core structure of the subgraph formed by them, referred to as the Reciprocal Network of Google+ — in a sense, a Reciprocal Network can be viewed as the stable “skeleton” Network of a directed online social Network that holds it together. We develop an effective three-step procedure to hierarchically extract and unfold the core structure of a Network by building up and generalizing ideas from the existing k-shell decomposition and clique percolation approaches. Our scheme produces higher-level representations of the core structure of the Google+ Reciprocal Network and it reveals that there are ten subgraphs (“communities”) comprising of dense clusters of cliques lying at the center of the core structure of the Google+ Reciprocal Network. Together they form the core to which “peripheral” sparse subgraphs are attached. Furthermore, our analysis shows that the core structure of the Google+ Reciprocal Network is very stable as the Network evolves. Our results have implications in the design of algorithms for information flow, and in development of techniques for analyzing the vulnerability or robustness of online social Networks.
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unfolding the core structure of the Reciprocal graph of a massive online social Network
Conference on Combinatorial Optimization and Applications, 2016Co-Authors: Braulio Dumba, Zhi-li ZhangAbstract:Google+ (G+ in short) is a directed online social Network where nodes have either Reciprocal (bidirectional) edges or parasocial (one-way) edges. As Reciprocal edges represent strong social ties, we study the core structure of the subgraph formed by them, referred to as the Reciprocal Network of G+. We develop an effective three-step procedure to hierarchically extract and unfold the core structure of this Reciprocal Network. This procedure builds up and generalizes ideas from the existing k-shell decomposition and clique percolation approaches, and produces higher-level representations of the core structure of the G+ Reciprocal Network. Our analysis shows that there are seven subgraphs (“communities”) comprising of dense clusters of cliques lying at the center of the core structure of the G+ Reciprocal Network, through which other communities of cliques are richly connected. Together they form the core to which “peripheral” sparse subgraphs are attached.
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COCOA - Unfolding the Core Structure of the Reciprocal Graph of a Massive Online Social Network
Combinatorial Optimization and Applications, 2016Co-Authors: Braulio Dumba, Zhi-li ZhangAbstract:Google+ (G+ in short) is a directed online social Network where nodes have either Reciprocal (bidirectional) edges or parasocial (one-way) edges. As Reciprocal edges represent strong social ties, we study the core structure of the subgraph formed by them, referred to as the Reciprocal Network of G+. We develop an effective three-step procedure to hierarchically extract and unfold the core structure of this Reciprocal Network. This procedure builds up and generalizes ideas from the existing k-shell decomposition and clique percolation approaches, and produces higher-level representations of the core structure of the G+ Reciprocal Network. Our analysis shows that there are seven subgraphs (“communities”) comprising of dense clusters of cliques lying at the center of the core structure of the G+ Reciprocal Network, through which other communities of cliques are richly connected. Together they form the core to which “peripheral” sparse subgraphs are attached.
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analysis of a Reciprocal Network using google structural properties and evolution
5th International Conference on Computational Social Networks CSoNet 2016, 2016Co-Authors: Braulio Dumba, Golshan Golnari, Zhi-li ZhangAbstract:Many online social Networks such as Twitter, Google+, Flickr and Youtube are directed in nature, and have been shown to exhibit a nontrivial amount of reciprocity. Reciprocity is defined as the ratio of the number of Reciprocal edges to the total number of edges in the Network, and has been well studied in the literature. However, little attention is given to understand the connectivity or Network form by the Reciprocal edges themselves (Reciprocal Network), its structural properties, and how it evolves over time. In this paper, we bridge this gap by presenting a comprehensive measurement-based characterization of the connectivity among Reciprocal edges in Google+ and their evolution over time, with the goal to gain insight into the structural properties of the Reciprocal Network. Our analysis shows that the Reciprocal Network of Google+ reveals some important user behavior patterns, which reflect how the social Network was being adopted over time.
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CSoNet - Analysis of a Reciprocal Network Using Google+: Structural Properties and Evolution
Computational Social Networks, 2016Co-Authors: Braulio Dumba, Golshan Golnari, Zhi-li ZhangAbstract:Many online social Networks such as Twitter, Google+, Flickr and Youtube are directed in nature, and have been shown to exhibit a nontrivial amount of reciprocity. Reciprocity is defined as the ratio of the number of Reciprocal edges to the total number of edges in the Network, and has been well studied in the literature. However, little attention is given to understand the connectivity or Network form by the Reciprocal edges themselves (Reciprocal Network), its structural properties, and how it evolves over time. In this paper, we bridge this gap by presenting a comprehensive measurement-based characterization of the connectivity among Reciprocal edges in Google+ and their evolution over time, with the goal to gain insight into the structural properties of the Reciprocal Network. Our analysis shows that the Reciprocal Network of Google+ reveals some important user behavior patterns, which reflect how the social Network was being adopted over time.
Braulio Dumba - One of the best experts on this subject based on the ideXlab platform.
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Uncovering the nucleus of a massive Reciprocal Network
World Wide Web, 2019Co-Authors: Braulio Dumba, Zhi-li ZhangAbstract:Google+ is a directed online social Network where nodes have either Reciprocal (bidirectional) edges or parasocial (one-way) edges. As Reciprocal edges play an important role in the structural properties, formation and evolution of online social Networks, we study the core structure of the subgraph formed by them, referred to as the Reciprocal Network of Google+ — in a sense, a Reciprocal Network can be viewed as the stable “skeleton” Network of a directed online social Network that holds it together. We develop an effective three-step procedure to hierarchically extract and unfold the core structure of a Network by building up and generalizing ideas from the existing k-shell decomposition and clique percolation approaches. Our scheme produces higher-level representations of the core structure of the Google+ Reciprocal Network and it reveals that there are ten subgraphs (“communities”) comprising of dense clusters of cliques lying at the center of the core structure of the Google+ Reciprocal Network. Together they form the core to which “peripheral” sparse subgraphs are attached. Furthermore, our analysis shows that the core structure of the Google+ Reciprocal Network is very stable as the Network evolves. Our results have implications in the design of algorithms for information flow, and in development of techniques for analyzing the vulnerability or robustness of online social Networks.
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unfolding the core structure of the Reciprocal graph of a massive online social Network
Conference on Combinatorial Optimization and Applications, 2016Co-Authors: Braulio Dumba, Zhi-li ZhangAbstract:Google+ (G+ in short) is a directed online social Network where nodes have either Reciprocal (bidirectional) edges or parasocial (one-way) edges. As Reciprocal edges represent strong social ties, we study the core structure of the subgraph formed by them, referred to as the Reciprocal Network of G+. We develop an effective three-step procedure to hierarchically extract and unfold the core structure of this Reciprocal Network. This procedure builds up and generalizes ideas from the existing k-shell decomposition and clique percolation approaches, and produces higher-level representations of the core structure of the G+ Reciprocal Network. Our analysis shows that there are seven subgraphs (“communities”) comprising of dense clusters of cliques lying at the center of the core structure of the G+ Reciprocal Network, through which other communities of cliques are richly connected. Together they form the core to which “peripheral” sparse subgraphs are attached.
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COCOA - Unfolding the Core Structure of the Reciprocal Graph of a Massive Online Social Network
Combinatorial Optimization and Applications, 2016Co-Authors: Braulio Dumba, Zhi-li ZhangAbstract:Google+ (G+ in short) is a directed online social Network where nodes have either Reciprocal (bidirectional) edges or parasocial (one-way) edges. As Reciprocal edges represent strong social ties, we study the core structure of the subgraph formed by them, referred to as the Reciprocal Network of G+. We develop an effective three-step procedure to hierarchically extract and unfold the core structure of this Reciprocal Network. This procedure builds up and generalizes ideas from the existing k-shell decomposition and clique percolation approaches, and produces higher-level representations of the core structure of the G+ Reciprocal Network. Our analysis shows that there are seven subgraphs (“communities”) comprising of dense clusters of cliques lying at the center of the core structure of the G+ Reciprocal Network, through which other communities of cliques are richly connected. Together they form the core to which “peripheral” sparse subgraphs are attached.
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analysis of a Reciprocal Network using google structural properties and evolution
5th International Conference on Computational Social Networks CSoNet 2016, 2016Co-Authors: Braulio Dumba, Golshan Golnari, Zhi-li ZhangAbstract:Many online social Networks such as Twitter, Google+, Flickr and Youtube are directed in nature, and have been shown to exhibit a nontrivial amount of reciprocity. Reciprocity is defined as the ratio of the number of Reciprocal edges to the total number of edges in the Network, and has been well studied in the literature. However, little attention is given to understand the connectivity or Network form by the Reciprocal edges themselves (Reciprocal Network), its structural properties, and how it evolves over time. In this paper, we bridge this gap by presenting a comprehensive measurement-based characterization of the connectivity among Reciprocal edges in Google+ and their evolution over time, with the goal to gain insight into the structural properties of the Reciprocal Network. Our analysis shows that the Reciprocal Network of Google+ reveals some important user behavior patterns, which reflect how the social Network was being adopted over time.
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CSoNet - Analysis of a Reciprocal Network Using Google+: Structural Properties and Evolution
Computational Social Networks, 2016Co-Authors: Braulio Dumba, Golshan Golnari, Zhi-li ZhangAbstract:Many online social Networks such as Twitter, Google+, Flickr and Youtube are directed in nature, and have been shown to exhibit a nontrivial amount of reciprocity. Reciprocity is defined as the ratio of the number of Reciprocal edges to the total number of edges in the Network, and has been well studied in the literature. However, little attention is given to understand the connectivity or Network form by the Reciprocal edges themselves (Reciprocal Network), its structural properties, and how it evolves over time. In this paper, we bridge this gap by presenting a comprehensive measurement-based characterization of the connectivity among Reciprocal edges in Google+ and their evolution over time, with the goal to gain insight into the structural properties of the Reciprocal Network. Our analysis shows that the Reciprocal Network of Google+ reveals some important user behavior patterns, which reflect how the social Network was being adopted over time.
Shanthi Pavan - One of the best experts on this subject based on the ideXlab platform.
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simplified unified analysis of switched rc passive mixers samplers and n path filters using the adjoint Network
IEEE Transactions on Circuits and Systems I-regular Papers, 2017Co-Authors: Shanthi Pavan, Eric A M KlumperinkAbstract:Recent innovations in software defined CMOS radio transceiver architectures heavily rely on high-linearity switched- RC sampler and passive-mixer circuits, driven by digitally programmable multiphase clocks. Although seemingly simple, the frequency domain analysis of these linear periodically time variant (LPTV) circuits is often deceptively complex. This paper uses the properties of sampled LPTV systems and the adjoint (inter-Reciprocal) Network to greatly simplify the analysis of the switched- RC circuit. We first derive the transfer function of the equivalent linear time-invariant filter relating the input to the voltage sampled on the capacitor in the switched- RC kernel. We show how a leakage resistor across the capacitor can be easily addressed using our technique. A signal-flow graph is then developed for the complete continuous-time voltage waveform across the capacitor, and simplified for various operating regions. We finally derive the noise properties of the kernel. The results we derive have largely been reported in prior works, but the use of the adjoint Network simplifies the derivation, while also providing circuit insight.
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Analysis of Chopped Integrators, and Its Application to Continuous-Time Delta-Sigma Modulator Design
IEEE Transactions on Circuits and Systems I: Regular Papers, 2017Co-Authors: Shanthi PavanAbstract:Chopping is a commonly used technique to eliminate flicker noise in amplifiers. We investigate the use of chopping in the input integrator of a continuous-time oversampling ( $\Delta \!\Sigma $ ) converter. Unlike an amplifier, the integrator in a continuous-time delta-sigma modulator is subject to out-of-band signals that are several orders of magnitude higher than the (desired) in-band component. This necessitates a careful analysis of frequency translation effects in a chopped integrator. This paper treats the chopped integrator as a linear periodically time-varying system, and exploits the adjoint (inter-Reciprocal) Network concept to simplify the analysis of aliasing effects in such an integrator. Simulation results that confirm the theory are given.
Songbin Gong - One of the best experts on this subject based on the ideXlab platform.
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a radio frequency non Reciprocal Network based on switched acoustic delay lines
arXiv: Signal Processing, 2018Co-Authors: Tomas Manzaneque, Yansong Yang, Liuqing Gao, Anming Gao, Songbin GongAbstract:This work demonstrates the first non-Reciprocal Network based on switched low-loss acoustic delay lines. The 4-port circulator is built upon a recently reported frequency-independent, programmable, non-Reciprocal framework based on switched delay lines. The design space for such a system, including the origins of the insertion loss and harmonic responses, is theoretically investigated, illustrating that the key to better performance and low-cost modulation signal synthesis lies in a large delay. To implement a large delay, we resort to in-house fabricated low-loss, wide-band lithium niobate (LiNbO3) SH0 mode acoustic delay lines employing single-phase unidirectional transducers (SPUDT). The 4-port circulator, consisting of two switch modules and one delay line module, has been modularly designed, assembled, and tested. The design process employs time-domain full circuit simulation and the results match well with measurements. A 18.8 dB non-Reciprocal contrast between insertion loss (IL = 6.6 dB) and isolation (25.4 dB) has been achieved over a fractional bandwidth of 8.8% at a center frequency 155 MHz, using a record low switching frequency of 877.19 kHz. The circulator also shows 25.9 dB suppression for the intra-modulated tone and 30 dBm for IIP3. Upon further development, such a system can potentially lead to future wide-band, low-loss chip-scale nonReciprocal RF systems with unprecedented programmability.
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A Radio Frequency Non-Reciprocal Network Based on Switched Low-Loss Acoustic Delay Lines
2018 IEEE International Ultrasonics Symposium (IUS), 2018Co-Authors: Tomas Manzaneque, Yansong Yang, Liuqing Gao, Anming Gao, Songbin GongAbstract:This work demonstrates the first 4-port radio frequency circulator based on switched low-loss acoustic delay lines. The 4-port circulator is built upon a recently reported frequency-independent, programmable, and non-Reciprocal framework based on switched delay lines. Large delays provided by the in-house fabricated, low-loss, and wide-band lithium niobate (LiNbO 3 )SH0 mode acoustic delay lines are leveraged to produce high performance and reduce the modulation effort simultaneously for enabling non-reciprocity. The implemented 4-port circulator has been demonstrated with an 18.8 dB non-recip-rocal contrast between the insertion loss (IL = 6.6 dB)and isolation (25.4 dB)over a fractional bandwidth of 8.8% at a center frequency 155 MHz, using a record low switching frequency of 877.19 kHz. The circulator also shows 25.9 dB suppression for the intra-modulated tones. Upon further development, such a system can potentially lead to wide-band, low-loss chip-scale nonReciprocal RF systems with unprecedented programmability.
Leandros Tassiulas - One of the best experts on this subject based on the ideXlab platform.
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transmit beamforming and power control for cellular wireless systems
IEEE Journal on Selected Areas in Communications, 1998Co-Authors: F Rashidfarrokhi, K J R Liu, Leandros TassiulasAbstract:Joint power control and beamforming schemes are proposed for cellular systems where adaptive arrays are used only at base stations. In the uplink, mobile power and receiver diversity combining vectors at the base stations are calculated jointly. The mobile transmitted power is minimized, while the signal-to-interference-and-noise ratio (SINR) at each link is maintained above a threshold. A transmit diversity scheme for the downlink is also proposed where the transmit weight vectors and downlink power allocations are jointly calculated such that the SINR at each mobile is above a target value. The proposed algorithm achieves a feasible solution for the downlink if there is one and minimizes the total transmitted power in the Network. In a Reciprocal Network it can be implemented in a decentralized system, and it does not require global channel response measurements. In a nonReciprocal Network, where the uplink and downlink channel responses are different, the proposed transmit beamforming algorithm needs to be implemented in a centralized system, and it requires a knowledge of the downlink channel responses. The performances of these algorithms are compared with previously proposed algorithms through numerical studies.
