Matrix Topology Research Articles

Reconstruction of enterprise debt networks based on compressed sensing

This study aims at the problem of reconstruction the unknown links in debt networks among enterprises. We use the topological matrix of the enterprise debt network as the object of reconstruction and use the time series data of accounts receivable and payable as input and output information in the debt network to establish an underdetermined linear system about the topological matrix of the debt network. We establish an iteratively reweighted least-squares algorithm, which is an algorithm in compressed sensing. This algorithm uses reweighted ell _2-minimization to approximate ell _1-norm of the target vectors. We solve the ell _1-minimization problem of the underdetermined linear system using the iteratively reweighted least-squares algorithm and obtain the reconstructed topological matrix of the debt network. Simulation experiments show that the topology matrix reconstruction method of enterprise debt networks based on compressed sensing can reconstruct over 70% of the unknown network links, and the error is controlled within 2%.

Controllability of networked systems with heterogeneous dynamics

Hao et al. (Int J Robust Nonlinear Control 28(5):1778–1788, 1976) established necessary and sufficient conditions for the controllability of homogeneous networked systems where the individual nodes are linear time-invariant (LTI) systems and the network topology matrix is diagonalizable. In this paper, we consider a class of heterogeneous networked systems having triangularizable network topology. Here, we establish a result which gives necessary and sufficient conditions for controllability of a class of heterogeneous systems, which generalizes the result of Hao et al. (Int J Robust Nonlinear Control 28(5):1778–1788, 1976). Also, we provide some necessary conditions for the controllability of general heterogeneous networked systems having some restrictions on the network topology matrix. Theoretical results are illustrated with numerical examples.

Dielectric Properties of Graphite Oxide Polymeric Composites Based on N-Vinylpirrolidone Copolymers with Different Topologies

The dielectric properties of graphite oxide composite materials based on a biocompatible branched copolymer of N-vinylpyrrolidone with 1,6-hexanediol dimethacrylate and a cross-linked copolymer of N‑vinylpyrrolidone with triethylene glycol dimethacrylate are studied. High-frequency (9.8 GHz) and low-frequency (25 Hz–1 MHz) measurements of the complex permittivity and electrical conductivity of polymer composites are carried out and their dependences on the polymer matrix topology and formation conditions are analyzed. Copolymers and composites based on them are characterized by IR, UV, and visible spectroscopy, dynamic light scattering, and the surface morphology of nanocomposite polymer matrices is characterized by optical microscopy. It is shown that the proposed electrophysical approach makes it possible to additionally characterize polymer matrices with carbon nanofillers.

Novel Compact Half-Mode SIW Bandpass Filters Based on Quad-Mode Resonator

Novel wideband half-mode substrate integrated waveguide (SIW) bandpass filters based on the quad-mode resonator are proposed in this brief. The proposed half-mode SIW bandpass filter A is composed of two half-mode SIW structures and two T-shaped slots on the top surface. The coupling matrix topology and equivalent circuit model are presented to analyze the performance. The wide band of filter A is designed on the basis of quad-mode resonator (TE101, TE102, TE103, and TE104). Besides, it can generate one transmission zero on the upper stopband due to the equivalent inductance (connecting metallic line between two half-mode SIWs) and the mutual capacitance coupling between two SIWs according to the equivalent circuit model. On the basis of filter A, two open-ended microstrip lines are added near the input and output ports (This filter is named by filter B), which will introduce two transmission zeros (TZs) in the lower stopband. The introduced TZs can improve the out-of-band rejection on the lower sideband. The resonant frequencies of the four modes are controlled by the T-shaped slots on the upper metal plate, which can reduce the overall size, significantly. The proposed two filters have compact size of 47.9mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathbf {\times }\,\,14.9$ </tex-math></inline-formula> mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathbf {\times }\,\,2$ </tex-math></inline-formula> mm. The prototypes have been fabricated and measured, and the measured results have a good agreement with the simulated ones.

Kinematic joint matrix and block diagram for a group of parallel manipulators

AbstractThere are various matrices to represent parallel mechanisms. It is essential to design a kind of approach to not only denote the parallel structures but also disclose the joint directions. In this paper, a novel methodology called the kinematic joint matrix (KJM) is proposed. It possesses the mapping relations with parallel manipulators with three kinds of kinematic joints. The size of such matrix is smaller when compared with that of topology matrix. A series of two to six degrees-of-freedom parallel architectures is denoted by the KJM. A convenient approach using a special block diagram is introduced to distinguish various kinds of kinematic joint matrices. In addition, detailed comparisons between KJM and topology matrix are investigated. Three regulations are proposed for the latter to be applicable to parallel mechanisms.

A Novel False Data Injection Attack Formulation Based on CUR Low-Rank Decomposition Method

State estimation algorithms deployed in modern grids are vulnerable towards false data injection attacks. This work demonstrates a novel attack vector (AV) formulation scheme by exploiting the low-rank subspace of the topology matrix. With constraints over the state deviation vector, this work showcases that the developed AV can effectively bypass the residue test for a demonstrated test bench.

Design and Analysis of Dual Input Z-Source Matrix Converter

Abstract: Series Z-Source community, connecting in helping vast o preferred concept of Z-supply dc hyperlink, changed into initially projected for boosting the output voltage of strength digital inverters. Throughout this paper, that idea is prolonged on a three-section oblique matrix converter. The converter relies upon at the ultra-sparse matrix topology characterised via way of means of the minimal vary of semiconductor switches. The collection Z-supply community is positioned among the three-transfer enter rectifier level and moreover the six-transfer output electric converter level, in both the wonderful or terrible rail. A short shoot-via nation produces the voltage raise. Associate in Nursing optimum pulse breadth modulation approach is advanced for better boosting capability of the converter and decrease of transfer losses. A evaluation is made among the matrix converters mistreatment collection and standard cascade Zsource networks. The inpouring modern-day and Z-supply capacitor’s voltage are decreased in the collection Z-supply matrix converter.

Collective cell migration during optic cup formation features changing cell-matrix interactions linked to matrix topology

Cell migration is crucial for organismal development and shapes organisms in health and disease. Although a lot of research has revealed the role of intracellular components and extracellular signaling in driving single and collective cell migration, the influence of physical properties of the tissue and the environment on migration phenomena invivo remains less explored. In particular, the role of the extracellular matrix (ECM), which many cells move upon, is currently unclear. To overcome this gap, we use zebrafish optic cup formation, and by combining novel transgenic lines and image analysis pipelines, we study how ECM properties influence cell migration invivo. We show that collectively migrating rim cells actively move over an immobile extracellular matrix. These cell movements require cryptic lamellipodia that are extended in the direction of migration. Quantitative analysis of matrix properties revealed that the topology of the matrix changes along the migration path. These changes in matrix topologies are accompanied by changes in the dynamics of cell-matrix interactions. Experiments and theoretical modeling suggest that matrix porosity could be linked to efficient migration. Indeed, interfering with matrix topology by increasing its porosity results in a loss of cryptic lamellipodia, less-directed cell-matrix interactions, and overall inefficient migration. Thus, matrix topology is linked to the dynamics of cell-matrix interactions and the efficiency of directed collective rim cell migration during vertebrate optic cup morphogenesis.

Alleviating the over-smoothing of graph neural computing by a data augmentation strategy with entropy preservation

The Graph Convolutional Networks (GCN) proposed by Kipf and Welling is an effective model to improve semi-supervised learning of pattern recognition, but faces the obstacle of over-smoothing, which will weaken the representation ability of GCN. Recently some works are proposed to tackle above limitation by randomly perturbing graph topology or feature matrix to generate data augmentations as input for training. However, these operations inevitably do damage to the integrity of information structures and have to sacrifice the smoothness of feature manifold. In this paper, we first introduce a novel graph entropy definition as a measure to quantitatively evaluate the smoothness of a data manifold and then point out that this graph entropy is controlled by triangle motif-based information structures. Considering the preservation of graph entropy, we propose an effective strategy to generate randomly perturbed training data but maintain both graph topology and graph entropy. Extensive experiments have been conducted on real-world datasets and the results verify the effectiveness of our proposed method in improving semi-supervised node classification accuracy compared with a surge of baselines. Beyond that, our proposed approach could significantly enhance the robustness of training process for GCN.

Formation preview tracking for heterogeneous multi-agent systems: A dynamical feedforward output regulation approach

The distributed formation tracking with preview information is investigated for discrete-time heterogeneous linear multi-agent systems (MASs) over directed communication networks. Firstly, by constructing an augmented system containing virtual regulation output and previewable information, the original problem is converted into a state regulation problem. Secondly, due to the coupling restriction of the eigenvalues of the exosystem matrix and the communication topology matrix, a linear distributed observer is proposed by introducing two extra parameters to realize asymptotic estimation. Using the output information of the observer, the problem was further formulated in the form of feedforward output regulation. Moreover, by solving the output regulation problem, the sufficient conditions are deduced for ensuring the achievement of the formation preview tracking. Meanwhile, numerical simulations show that the distributed design with preview actions has positive effect on the improvement of the transient response.

Structural analysis of traditional Chinese complex puzzle locks

The development of barbed-spring locks in ancient China has a history of more than 2000 years. With the development of the design and manufacturing techniques in ancient China, the safety of locks has gotten better and better. Since the seventeenth century, the puzzle lock, with a complicated structure and a high difficulty in opening, was gradually developed and used. The puzzle lock needs specific steps to be opened. Based on the difficulty of the opening process, traditional Chinese puzzle locks can be partition into two sorts, namely, general puzzle locks and complex puzzle locks. As the structure of the puzzle lock will change during the opening process, the puzzle lock belongs to the reconfigurable mechanism. In this paper, a method of topology matrix is provided to analyze the structure of the complex puzzle lock during systematical operation. Firstly, the characteristics and types of general puzzle locks are explained, and then the topology matrix representation is introduced. Finally, four complex puzzle locks are taken as examples, to illustrate the opening process. There are various types of complex puzzle locks, and the mechanism designs are quite ingenious and interesting, which shows the extraordinary technique and ingenuity of the ancient craftsmen.

Graph-Based Power Flow Algorithm for Three-Phase Distribution Network Considering Regulators and Distributed Generations

In this article, a new approach for solving the power flow (PF) problem of distributed generations (DGs) integrated three-phase distribution networks is proposed that is based on backward-forward sweep, graph theory, and matrix algebra. The key concept is the formation of two matrices, one that depicts the configuration or structure of the distribution system (these matrices are connectivity matrix and bus-branch topology matrix) and the second which is directly involved in computing PF parameters. The major advantage of the architecture is that the size of matrices and sparsity problems can be handled better than contemporary approaches making the approach very robust and efficient. To emulate the feature of DGs modeled as PV bus into the proposed power flow algorithm, a PV injection sensitivity matrix has been developed which facilitates computation of the required reactive power injections to offset the voltage deviation at PV bus. The computed injection is replicated in the PF using PV current beyond the branch matrix and net branch current matrix. Several test analyses have been carried out to validate the viability and efficiency of the proposed PF algorithm.

High-accuracy design for mesh antennas considering the metallic mesh

Metallic meshes have great effects on the surface accuracy and tension distribution of mesh antennas, which present considerable challenges to the high-accuracy design of reflectors. Unfortunately, the metallic mesh is usually neglected in current research due to the complex coupling between the metallic mesh and the cable network. This paper presents a novel high-accuracy design method for the mesh reflector considering the effect of the metallic mesh. A cable-membrane coupling model is first proposed to account for the compatible deformation between the cable network and the metallic mesh. By introducing the topology matrix of the cable-membrane structure, the unified equilibrium equation of the mesh antenna is established and solved by the dynamic relaxation (DR) method. A novel high-accuracy design method for the mesh antenna is proposed by optimising the geometric dimensions of the cables and the membranes. Finally, this method is effectively applied to the high-accuracy design of two mesh antennas with different topologies considering the effect of the metallic mesh. The superiority of the method is demonstrated through a comparison with the literature, and the accuracy of the results is exhibited by the FEM software ABAQUS.

Network synchronization under distributed delayed impulsive control: Average delayed impulsive weight approach

This paper mainly investigates synchronization of complex dynamical networks (CDNs) with both system delay and coupled delay through distributed delayed impulsive control. Instead of constraining the impulsive weight and impulsive delay one by one, a new concept of average delayed impulsive weight is proposed to obtain more relaxed conditions. Subsequently, based on the impulsive control topology, Lyapunov theory and linear matrix inequality (LMI) design, certain flexible criteria of global exponential synchronization (GES) are given and the corresponding convergence rate is estimated. It is interesting to see that the CDNs can still achieve synchronization under comprehensive conditions though impulsive weights work negatively. Namely, the delays in impulsive control are able to promote synchronization potentially. Finally, simulations are given to show that the distributed delayed impulsive control can not only speeds up the convergence rate for synchronized networks, but also facilitates synchronization for desynchronized networks. In addition, the obtained results can be applied to unmanned craft systems.

Precision-engineered niche for directed differentiation of MSCs to lineage-restricted mineralized tissues

The major difference between tissue healing and regeneration is the extent of instructional cues available to precisely direct the biological response. A classic example is reparative or osteodentin that is seen in response to physicochemical injury to the pulp-dentin complex. Dentin regeneration can direct the differentiation of dental stem cells using concerted actions of both soluble (biomolecules, agonists, and antagonists) and insoluble (matrix topology) cues. The major purpose of this study was to examine the synergistic combination of two discrete biomaterial approaches by utilizing nanofiber scaffolds in discrete configurations (aligned or random) with incorporated polymeric microspheres capable of controlled release of growth factors. Further, to ensure appropriate disinfection for clinical use, Radio-Frequency Glow Discharge (RFGD) treatments were utilized, followed by seeding with a mesenchymal stem cell (MSC) line. SEM analysis revealed electrospinning generated controlled architectural features that significantly improved MSC adhesion and proliferation on the aligned nanofiber scaffolds compared to randomly oriented scaffolds. These responses were further enhanced by RFGD pre-treatments. These enhanced cell adhesion and proliferative responses could be attributed to matrix-induced Wnt signaling that was abrogated by pre-treatments with anti-Wnt3a neutralizing antibodies. Next, we incorporated controlled-release microspheres within these electrospun scaffolds with either TGF-β1 or BMP4. We observed that these scaffolds could selectively induce dentinogenic or osteogenic markers (DSPP, Runx2, and BSP) and mineralization. This work demonstrates the utility of a novel, modular combinatorial scaffold system capable of lineage-restricted differentiation into bone or dentin. Future validation of this scaffold system in vivo as a pulp capping agent represents an innovative dentin regenerative approach capable of preserving tooth pulp vitality.

Stochastic Modeling and Convergence Analysis of Internet Routers

The existent route convergence models are mainly deterministic ones, and various phenomena, such as packet losses, link noises, and sudden changes in interconnecting topology will occur in the route convergence process. Aimed at these random problems, a new stochastic dynamic system model was proposed by means of the Bernoulli white sequence distribution, the Wiener process and the Markov process. Based on the stochastic differential equation theory and the stochastic analysis methods, the sufficient conditions for the route convergence were given. The results prove that, the convergence of the routing state in a random environment is closely related to the Laplacian matrix of the router connection topology, the smooth distribution of the Markov switching, the successful transmission rate of the data packets, and the noise intensity in the network. Finally, a numerical example illustrates the effectiveness of the results.

Analytical Design Method and Implementation of Broadband 4 × 4 Nolen Matrix

Beamforming techniques are widely used in antenna array systems. One of the most popular beamforming networks (BFNs) is Nolen matrix, which can achieve flexible phase progression. However, due to the lack of analysis on phase slope alignments between internal components, the conventional topology-based Nolen matrix exhibits narrow bandwidth. To overcome this shortage, an analytical design method based on signal flow graphs (SFGs) and complex exponential signal is proposed. With the use of this analytical design method, rigorous relationships of phase slope alignments between couplers and phase shifters within the operating band in the traditional <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4\times $ </tex-math></inline-formula> 4 Nolen matrix topology can be derived. Based on this, a novel <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4\times $ </tex-math></inline-formula> 4 Nolen matrix topology composed of couplers and differential phase shifters (DPSs) with specific phase difference slopes is proposed. For verification, a broadband <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4\times $ </tex-math></inline-formula> 4 Nolen matrix based on the proposed topology centered at 1.8 GHz, is designed, fabricated, and measured. Simulated and measured results are in good agreement. The measured bandwidths of ports 1–4 defined by return losses and isolations (15 dB for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$S_{i1}$ </tex-math></inline-formula> , 10 dB for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$S_{ij,i = 1-4, j = 2-4}$ </tex-math></inline-formula> ) and 1 dB amplitude imbalance are 41.49%, 46.21%, 40%, and 48.24%, respectively. Phase errors are within ±5° for 0° and ±90° phase progressions and vary within the range from −10° to 5° for 180° phase progression. The proposed Nolen matrix exhibits the widest bandwidth and the flattest phase progression among Nolen matrices in existence, which verifies the validity of the proposed analytical design method.

Design of Wideband Butler Matrix With Equal/Unequal Phase Differences for Flexible Beam-Controllability

This brief presents a new generic wideband Butler matrix topology with an expanded range of radiation beam angle. Both Butler matrix with equal phase differences (BM EPD) and Butler matrix with unequal phase differences (BM UEPD) are studied and simulated, and the equations of the array factor are derived. Arbitrary phase differences have been realized when different input ports are excited, referring to flexible beam controllability. To prove the design concept, a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4\times 4$ </tex-math></inline-formula> UEPD BM operating at 3.5 GHz and a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4\times 4$ </tex-math></inline-formula> EPD BM operating at 4.9 GHz are demonstrated and fabricated respectively. A linear antenna array consisting of printed dipoles with integrated balun is integrated with the Butler matrix for verification of its radiation beam steering. The simulation and measurement results agree well with the theoretical analysis.

Finite-time distributed event-triggered formation control for quadrotor UAVs with experimentation

This paper deals with the finite-time event-triggered formation control problem for multiple quadrotor unmanned aerial vehicles (UAVs) with unknown external disturbances. Novel adaptive distributed robust event-triggered controllers without/with finite-time extended state observer (FTESO) are developed based on adaptive terminal sliding mode (TSM) control method to save control update times and reduce chattering times simultaneously. It is proved that the proposed control strategies guarantee that all the closed-loop signals are practically finite-time stable. Moreover, the proposed controllers are fully distributed without the global information that is related to the communication topology matrix H. Meanwhile, the controller with FTESO is anti-disturbance. Zeno behavior is excluded by the strictly positive sampling intervals. Finally, the efficiency of the proposed control algorithms is illustrated by numerical simulations and three bebop2 quadrotor UAVs experimentation.

Efficient FPGA-Based Real-Time Implementation of Model Predictive Control for Single-Phase Direct Matrix Converter

Finite control set model predictive control (FCS-MPC) is an optimal control strategy that solves user-defined objective functions to determine the best control action for the next time interval. Real-time implementations of model predictive control techniques are quite challenging for certain topologies due to computation complexities. In this paper, key aspects of achieving robust, reliable, and efficient field programmable gate arrays (FPGAs) based model predictive control are presented for single-phase direct matrix topology. The effectiveness of FPGA-based model predictive control is validated experimentally using an ALTERA Cyclone IV FPGA. Experimental results show that an effective load current control performance is obtained by taking advantage of pipelining capability of the FPGA device. The tradeoff between control bandwidth, FPGA resources, and hardware utilization is discussed.