257 research outputs found
Achieving full diversity in multi-antenna two-way relay networks via symbol-based physical-layer network coding
This paper considers physical-layer network coding (PNC) with M-ary phase-shift keying (MPSK) modulation in two-way relay channel (TWRC). A low complexity detection technique, termed symbol-based PNC (SPNC), is proposed for the relay. In particular, attributing to the outer product operation imposed on the superposed MPSK signals at the relay, SPNC obtains the network-coded symbol (NCS) straightforwardly without having to detect individual symbols separately. Unlike the optimal multi-user detector (MUD) which searches over the combinations of all users’ modulation constellations, SPNC searches over only one modulation constellation, thus simplifies the NCS detection. Despite the reduced complexity, SPNC achieves full diversity in multi-antenna relay as the optimal MUD does. Specifically, antenna selection based SPNC (AS-SPNC) scheme and signal combining based SPNC (SC-SPNC) scheme are proposed. Our analysis of these two schemes not only confirms their full diversity performance, but also implies when SPNC is applied in multi-antenna relay, TWRC can be viewed as an effective single-input multiple-output (SIMO) system, in which AS-PNC and SC-PNC are equivalent to the general AS scheme and the maximal-ratio combining (MRC) scheme. Moreover, an asymptotic analysis of symbol error rate (SER) is provided for SC-PNC considering the case that the number of relay antennas is sufficiently large
Reliability analysis of the internet of things using Space Fault Network
The Internet of Things (IoT) is a network topology structure based on the interconnection of many nodes. It realizes the basic functions of IoT through the transmission of information, data, and energy between the nodes. To study the reliability of Internet of Things Network Topology (IoTNT) structure, we must abstract IoT as network topology and study the reliability of the network itself from the topology structure. This paper attempts to apply the Space Fault Network (SFN) to the study the reliability of IoTNT. To achieve this goal, the nodes and edges of IoTNT are equivalent to events and connections of SFN respectively. A structure analysis method based on SFN is proposed and used to study the reliability of IoTNT. At the same time, the influence of possible logical relationship between nodes on the reliability of IoTNT is studied. According to the SFN structure representation methods (SFNSRMs), considering different network structures and induced modes, the analysis methods and calculation methods of the evolution process of target event are given. An example is given to illustrate the analysis and calculation process. The research provides the new methods for the reliability study of IoT and the development of SFN
Municipal Government Use of Social Media: An Analysis of Three Chinese Cities
To investigate the use of information dissemination and public communication by Chinese municipal governments, we analyzed the social media use of three large cities with relatively mature social media development: Shanghai, Nanjing and Chengdu. We collected 4,429 government posts and users’ likes, shares and comments from Weibo accounts of each city’s information office. Government posts were coded into 7 types and 16 topics. We used cross-tabulation, correlation analysis and multivariate linear regression to analyze government posts, user responses and their inter-relationships. Chengdu has issued the most posts, while Nanjing has received the highest average user response to posts and exhibited the best signs of success in communication between the government and citizens
Entropy production in a mesoscopic chemical reaction system with oscillatory and excitable dynamics
Stochastic thermodynamics of chemical reaction systems has recently gained
much attention. In the present paper, we consider such an issue for a system
with both oscillatory and excitable dynamics, using catalytic oxidation of
carbon monoxide on the surface of platinum crystal as an example. Starting from
the chemical Langevin equations, we are able to calculate the stochastic
entropy production P along a random trajectory in the concentration state
space. Particular attention is paid to the dependence of the time averaged
entropy productionP on the system sizeN in a parameter region close to the
deterministic Hopf bifurcation.In the large system size (weak noise) limit, we
find that P N^{\beta} with {\beta}=0 or 1 when the system is below or abovethe
Hopf bifurcation, respectively. In the small system size (strong noise) limit,
P always increases linearly with N regardless of the bifurcation parameter.
More interestingly,P could even reach a maximum for some intermediate system
size in a parameter region where the corresponding deterministic system shows
steady state or small amplitude oscillation. The maximum value of P decreases
as the system parameter approaches the so-called CANARD point where the maximum
disappears.This phenomenon could be qualitativelyunderstood by partitioning the
total entropy production into the contributions of spikes and of small
amplitude oscillations.Comment: 13 pages, 6 figure
Coinductive subtyping for abstract compilation of object-oriented languages into Horn formulas
In recent work we have shown how it is possible to define very precise type
systems for object-oriented languages by abstractly compiling a program into a
Horn formula f. Then type inference amounts to resolving a certain goal w.r.t.
the coinductive (that is, the greatest) Herbrand model of f.
Type systems defined in this way are idealized, since in the most interesting
instantiations both the terms of the coinductive Herbrand universe and goal
derivations cannot be finitely represented. However, sound and quite expressive
approximations can be implemented by considering only regular terms and
derivations. In doing so, it is essential to introduce a proper subtyping
relation formalizing the notion of approximation between types.
In this paper we study a subtyping relation on coinductive terms built on
union and object type constructors. We define an interpretation of types as set
of values induced by a quite intuitive relation of membership of values to
types, and prove that the definition of subtyping is sound w.r.t. subset
inclusion between type interpretations. The proof of soundness has allowed us
to simplify the notion of contractive derivation and to discover that the
previously given definition of subtyping did not cover all possible
representations of the empty type
Dialectic tensions in the financial markets: a longitudinal study of pre- and post-crisis regulatory technology
This article presents the findings from a longitudinal research study on regulatory technology in the UK financial services industry. The financial crisis with serious corporate and mutual fund scandals raised the profile of
compliance as governmental bodies, institutional and private investors introduced a ‘tsunami’ of financial regulations. Adopting a multi-level analysis, this study examines how regulatory technology was used by financial firms to meet their compliance obligations, pre- and post-crisis. Empirical data collected over 12 years examine the deployment of
an investment management system in eight financial firms. Interviews with public regulatory bodies, financial
institutions and technology providers reveal a culture of compliance with increased transparency, surveillance and
accountability. Findings show that dialectic tensions arise as the pursuit of transparency, surveillance and
accountability in compliance mandates is simultaneously rationalized, facilitated and obscured by regulatory
technology. Responding to these challenges, regulatory bodies continue to impose revised compliance mandates on
financial firms to force them to adapt their financial technologies in an ever-changing multi-jurisdictional regulatory landscape
Dynamic elastic hysteretic solids and dislocations
Physical Review Letters, 94(8): pp. 085501-1—085501-4. Retrieved September 19, 2006 from http://www.mse.drexel.edu/max/pdf%20references/drexel_pdfs/papers/PhysRevLett_94_085501.pdf. DOI: http://dx.doi.org/10.1103/PhysRevLett.94.085501Recently we showed that the quasistatic response of nonlinear mesoscopic elastic solids to stress can be
explained by invoking the formation of dislocation-based incipient kink bands. In this Letter, using
resonant ultrasound spectroscopy, we confirm that the dynamical behavior of these nonlinear elastic
systems is due to the interaction of dislocations with the ultrasound waves, thus resolving a long-standing
mystery
Estimation of the OSNR penalty due to in-band crosstalk on the performance of virtual carrier-assisted metropolitan OFDM systems
The impact of the in-band crosstalk on the performance of virtual carrier (VC)-assisted direct detection (DD) multi-band orthogonal frequency division multiplexing (MB-OFDM) systems was numerically assessed via Monte-Carlo simulations, by means of a single interferer and 4-ary, 16-ary and 64-ary quadrature amplitude modulation (QAM) formats in the OFDM subcarriers. It was also investigated the influences of the virtual carrier-to-band power ratio (VBPR) and the virtual carrier-to-band gap (VBG) on the DD in-band crosstalk tolerance of the OFDM receiver. It was shown the modulation format order decrease enhances the tolerance to in-band crosstalk. When the VBG is the same for both interferer and selected signal, the interferer VBPR increase is seen to lead to lower optical signal-to-noise ratio (OSNR) penalties due to in-band crosstalk. Considering that the VCs frequencies of the selected and interferer OFDM signals are equal, the increase of the interferer VBG also gives rise to lower OSNR penalties. When the interferer and selected signals bands central frequencies are the same, the change of interferer VBG can attain 11 dB less tolerance to in-band crosstalk of the VC-assisted DD OFDM system. We also evaluate the error vector magnitude (EVM) accuracy of the in-band crosstalk tolerance of the DD OFDM receiver and our results show that the EVM estimations are inaccurate.info:eu-repo/semantics/acceptedVersio
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