Reconfigurable Performance Research Articles

Design and Implementation of a Wideband 1-Bit Transmitarray Based on a Yagi–Vivaldi Unit Cell

A novel 1-bit reconfigurable transmitarray antenna (RTA) based on a Yagi-Vivaldi unit cell for wideband and beam scanning application at the Ku-band is presented. The unit cell consists of a tightly coupled microstrip (MS) Yagi antenna and a Vivaldi antenna as the receiving and transmitting elements, respectively. To achieve a reconfigurable performance, a novel slot line to MS line phase shifter with a pair of reverse-mounted p-i-n diodes was introduced, and a 180° phase difference was achieved based on the current reversal mechanism. To improve the oblique incidence performance of the unit cell, a metasurface based on subwavelength metal crosses was loaded in front of the antenna, and the scan loss in the H-plane was improved by 2 dB. An RTA prototype with 16×16 unit cells was designed, fabricated, and tested. The measured 1 dB bandwidth of the RTA is 14% with a maximum gain of 22.3 dB at 13.6 GHz, corresponding to an aperture efficiency of 25.6%. Good beam scanning performance has also been achieved with a scan loss better than 4 dB in both the E-plane and the H-plane at 60°.

Lead firm’s reconfiguration decision and performance of the value chain

Purpose This paper aims to trace the performance consequences of within-lead firm reconfigurations of global value chains with respect to business performance and upgrading. Design/methodology/approach The study is based on two detailed company case studies which are analysed in an organizational design approach. Findings Lead firms systematically separate and internalize high value-added activities in otherwise low value-added processes leading to constant reconfigurations and reorganizations of the production processes in global value chains. The study finds that similar reconfigurations may trigger different changes and changes and performance consequences may differ considerably according to the level of analysis. The two cases help to understand the specific roles of the outsourcing and offshoring decisions in shaping actual global value chain structures. Originality/value The consequences of within-lead firm reconfigurations are rarely analysed in the literature.

Data-Driven Network Slicing From Core to RAN for 5G Broadcasting Services

Network slicing is a widely discussed technology for 5G broadcasting services, as it allows the operators to create end-to-end virtual slices across the 5G core (5GC) and the 5G radio access network (RAN). The joint network slicing is necessary for 5GC and 5G RAN in a bid to enhance the overall resource utilization and quality of service. Nevertheless, as the dimension of network resource and user demand increase, the computational complexity of slice status update goes up as well. To overcome this scalability problem, we propose a data driven approach to realize joint slice reconfiguration from 5GC to 5G RAN in real-time. Our design shortens significantly the time of slice status update by mapping the resource status to a two-dimensional vector graph. In addition, we also introduce a corresponding slice reconfiguration algorithm to balance the load of each slice in 5GC and 5G RAN. Simulation results justify that our proposed approach can greatly reduce the cost of slice status update and achieve desirable slice reconfiguration performance.

Online Reconfiguration of Distributed Robot Control Systems for Modular Robot Behavior Implementation

The use of autonomous robots in areas that require executing a broad range of different tasks is currently hampered by the high complexity of the software that adapts the robot controller to different situations the robot would face. Current robot software frameworks facilitate implementing controllers for individual tasks with some variability, however, their possibilities for adapting the controllers at runtime are very limited and don’t scale with the requirements of a highly versatile autonomous robot. With the software presented in this paper, the behavior of robots is implemented modularly by composing individual controllers, between which it is possible to switch freely at runtime, since the required transitions are calculated automatically. Thereby the software developer is relieved of the task to manually implement and maintain the transitions between different operational modes of the robot, what largely reduces software complexity for larger amounts of different robot behaviors. The software is realized by a model-based development approach. We will present the metamodels enabling the modeling of the controllers as well as the runtime architecture for the management of the controllers on distributed computation hardware. Furthermore, this paper introduces an algorithm that calculates the transitions between two controllers. A series of technical experiments verifies the choice of the underlying middleware and the performance of online controller reconfiguration. A further experiment demonstrates the applicability of the approach to real robotics applications.

Remotely controlled reconfigurable antenna for modern 5G networks applications

AbstractIn this work, a low‐profile antenna based on metamaterial (MTM) of a Hilbert‐shaped fractal with 3 × 2 array printed on a rectangular area and fed with a coplanar waveguide structure is exemplified for this study. The antenna is designed to show a reconfigurable performance that is remotely controlled through tuning the light intensity on an array of photo‐resistors to enable dynamic reconfiguration with control circuitry free wires over multiband of frequencies. From the measured antenna gain spectrum, a significant change in the antenna gain is found due to illuminating the photo‐resistors that suits the application of amplitude shift keying (ASK). For instance, at 2.45 GHz the gain is raised from 1.2 up to 7.8 dBi and at 5.8 GHz the gain enhancement is found about 6.6 dBi.

Broadband terahertz absorber with a flexible, reconfigurable performance based on hybrid-patterned vanadium dioxide metasurfaces.

An actively tunable broadband terahertz absorber is numerically demonstrated, which consists of four identical vanadium dioxide (VO2) square loops and a metal ground plane separated by a dielectric spacer. Simulation results show that an excellent absorption bandwidth of 90% terahertz absorptance reaches as wide as 2.45 THz from 1.85 to 4.3 THz under normal incidence. By changing the conductivity of VO2, an approximately perfect amplitude modulation is realized with the absorptance dynamically tuned from 4% to 100%. This absorption performance is greatly improved compared with previously reported VO2-based absorbers. The physical mechanisms of a single absorption band and the perfect absorption are elucidated by the wave-interference theory and the impedance matching theory, respectively. Field distributions are further discussed to explore the physical origin of this absorber. In addition, it also has the advantages of polarization insensitivity and wide-angle absorption. The proposed absorber may have many promising applications in the terahertz range such as modulator, sensor, cloaking and optic-electro switches.

A Novel Linear Sparse Array with Reconfigurable Pixel Antenna Elements

In this paper, on the basis of multifunctional reconfigurable pixel antenna (RPA) elements, a novel linear sparse array with an attractive compound reconfigurability is presented. It has the potential advantages of its beam scanning with low gain fluctuation, low sidelobe in two orthogonal planes, and polarization reconfigurable performance. Specifically, an RPA with simultaneous polarization and pattern reconstruction capabilities, consisting of the driven patch and the parasitic pixels on the same layer of dielectric substrate, is firstly designed, which can work in several operation modes corresponding to steerable beam directions θ=0°;θxoz=25°, 45°;θyoz=15° with two circular polarizations in X-band. Cross-slot coupling feed is used to improve polarization reconstruction capability and reduce the complexity of hybrid reconstruction topology optimization. Then, those RPAs are integrated into the 1×8 linear sparse array to realize the reconfiguration of two circular polarizations and beam steering in xoz- and yoz-plane. Simulation results show that the gain fluctuation and sidelobe level of the array during beam scanning have significant advantages over the previous phased array, and the generation of antenna grating lobes is avoided. Moreover, both RPA element and RPA array prototypes have been fabricated and measured to testify the efficiency. The measured results agree well with the simulated ones, which indicates the application potential in the field of modern wireless communication system of the proposed linear sparse array.

Reconfigurable symmetry-broken laser in a symmetric microcavity

The coherent light source is one of the most important foundations in both optical physics studies and applied photonic devices. However, the whispering gallery microcavity, as a prime platform for novel light sources, has the intrinsically chiral symmetry and severely rules out access to directional light output, all-optical flip-flops, efficient light extraction, etc. Here, we demonstrate a reconfigurable symmetry-broken microlaser in an ultrahigh-Q whispering gallery microcavity with the symmetric structure, in which a chirality of lasing field is empowered spontaneously by the optical nonlinear effect. Experimentally, the ratio of counter-propagating lasing intensities is found to exceed 160:1, and the chirality can be controlled dynamically and all-optically by the bias in the pump direction. This work not only presents a distinct recipe for coherent light sources with robust and reconfigurable performance, but also opens up an unexplored avenue to symmetry-broken physics in optical micro-structures.

New Hardware Static and Reconfigurable Architectures for Video Watermarking System

The watermarking technique is an active subject in current research used as a solution for copyright protection in multimedia documents. In this paper, we propose the first hardware invisible robust video watermarking application based on motion estimation. Since the designers of this application face many challenges, two types of architecture are performed: static and dynamic/partial reconfigurable architecture. The proposed architecture is adapted to HEVC encoded video. Two protection techniques are linked up: the digital watermarking to insert a watermark in the video, and the scrambling technique for overall video protection. The watermark embedding is treated in the horizontal and vertical components of even motion vectors. Eventually, the entire vectors are scrambled. The used watermark is a binary sequence where only one bit is inserted into the horizontal and the vertical components of motion vectors. The recommended architecture applies for slow and fast video sequence, where we use a motion estimator reconfigured according to the macro-block video movement. We also utilize a pipeline structure and a clock gating module to increase computing power and reduce power consumption. Experimental results show that the suggested static and dynamic/partial reconfigurable architecture guarantees material efficiency and superior performance in terms of frequency and power consumption.

Sequential Alliance Portfolios, Partner Reconfiguration and Firm Performance

This study develops multi-dimensional partner reconfiguration strategies and addresses how they affect firm performance in a series of alliance portfolios by applying the dynamic sustainable perspective. Using data collected from 565 fund product alliance portfolios initiated by 61 Chinese fund firms during a five-year period from 2007 to 2011, the empirical results indicate that both dropping active partners and adding new ones will reduce firm performance. By contrast, reintroducing previous partners will increase firm performance. The average tie strength of the last alliance portfolio moderates the influences of partner reconfigurations on firm performance. Specifically, it negatively moderates the effect of dropping active partners and positively moderates the effect of adding new partners. However, its moderating effect on the influence of reintroducing previous partners is insignificant. These findings have positive theoretical and practical significance for firms pursuing sustainable development by clarifying when and how partner reconfiguration strategies influence firm performance.

Reconfigurable metalattices: Combining multipolar lattice resonances and magneto-optical effect in far and near fields

The present work has elaborated the roles of near- and far-field lattice resonances (LRs) in the performance of one-dimensional metalattices composed of magneto-optically (MO) coated cylinders. By taking advantage of LR effects and MO-modified multipolar interferences, it is feasible to alter transmission or reflection with unity efficiency by turning on or off external magnetic fields. In the far field, multipolar LRs near Rayleigh anomaly (RA) can be acquired, leading to transmission suppression or enhancement for different multipolar interference mechanisms. Meanwhile, thanks to exciting degeneracy-broken multipoles, asymmetric diffractive patterns are observed despite normal incidence. However, in the diffractionless region with strong near-field couplings, we find that LR effects are capable of not only modifying scattering amplitude (>1) but also introducing phase change or even inversion. Specifically, owing to the appearance of π/2-phase rotated electric dipoles, the first and second Kerker conditions are achieved simultaneously in this work. In addition, the coupling mechanism of RA-associated LRs and MO-influenced Mie modes supported by an individual cylinder is also unveiled. Besides, a proof-of-concept example using realistic Si@InSb metalattices has also been demonstrated, showing reconfigurable performance as expected. The revealed far/near-field mechanism of interplay between LRs and MO-modified multipoles will shed new light on wavefront engineering with diffracted effects and reconfigurable features.

Fast signal reconstruction and recognition algorithm based on cascading redundant dictionary and block sparsity for compressed sensing radar receiver

The compressed sensing (CS) radar receiver based on the theory of CS has a great advantage in receiving wide-band signal and can receive high-frequency radar signal at a sampling rate far lower than the traditional receiver. However, in order to obtain the information of the target signal, the parameters of the reconstructed signal still need to be measured by conventional methods. In order to make full use of the compressed sampling and the characteristics of radar signals, this study proposed a cascading dictionary matching pursuit algorithm based on block-sparsity (BS-CDMP) to achieve fast identification and reconstruction of received signals. First, a signal-level redundant dictionary is constructed for quickly identifying the signal in which the authors are interested in. Then, they study the feasibility of cascading the signal-level redundant dictionary and the DFT basis as a whole sparsity dictionary. Finally, the block sparsity is introduced for the selection of different parts of the dictionary during greedy iteration. Experimental results show that their proposed algorithm has considerable and universal reconfiguration performance and can directly perform fast reconstruction and recognition of the target signal.

Spacecraft formation reconfiguration with multi-obstacle avoidance under navigation and control uncertainties using adaptive artificial potential function method

In this paper, an adaptive artificial potential function (AAPF) method is developed for spacecraft formation reconfiguration with multi-obstacle avoidance under navigation and control uncertainties. Furthermore, an improved Linear Quadratic Regular (ILQR) is proposed to track the reference trajectory and a Lyapunov-based method is employed to demonstrate the stability of the overall closed-loop system. Compared with the traditional APF method and the equal-collision-probability surface (ECPS) method, the AAPF method not only retains the advantages of APF method and ECPS method, such as low computational complexity, simple analytical control law and easy analytical validation progress, but also proposes a new APF to solve multi-obstacle avoidance problem considering the influence of the uncertainties. Moreover, the ILQR controller obtains high control accuracy to enhance the safe performance of the spacecraft formation reconfiguration. Finally, the effectiveness of the proposed AAPF method and the ILQR controller are verified by numerical simulations.

Cenas de leitura em Silviano Santiago

Resumo O objetivo do artigo é refletir acerca do papel da leitura na obra de Silviano Santiago. A primeira seção do trabalho é dedicada a apresentar um panorama dos usos da leitura e da figura do leitor em Silviano Santiago, tanto em sua obra ficcional quanto em sua obra ensaística, salientando a importância dos processos afetivos na escolha e no uso das referências literárias e teóricas (Graciliano Ramos, Barthes, Althusser). A segunda seção lida mais especificamente com o ensaio de Santiago “A vida como literatura” (2006), analisando as estratégias do autor no que diz respeito à sua leitura da obra de Cyro dos Anjos e sua peculiar problematização da vivência da subjetividade na leitura e na escritura, algo que é feito a partir do uso do significante “Silviano”, tanto como nome próprio do autor quanto como personagem de Cyro dos Anjos. Por fim, o artigo se deterá em uma entrevista de Silviano Santiago de 2004 na qual ele apresenta como tarefa de leitura a obra do escritor alemão W. G. Sebald. Diante desse posicionamento declarado como leitor e do estabelecimento dessa cena de leitura, busca-se investigar a presença dos procedimentos ficcionais de Sebald no último romance de Silviano Santiago, “Machado”, de 2016. Ao apresentar a figura do leitor como um ponto de atravessamento de diferença e repetição, Silviano Santiago faz do contato entre leitura e escritura uma performance de reconfiguração da tradição e das referências contemporâneas.

Design of a Multifunctional Reconfigurable Metasurface for Polarization and Propagation Manipulation

In this paper, a multifunctional reconfigurable polarization conversion metasurface (MRPCM) is designed for controlling both the propagation and the polarization of electromagnetic wave. The proposed metasurface contains two-layered structures separated by the air layer. The top layer is composed of two back-to-back C-shaped metallic resonators, which is used to convert the polarization. The bottom layer is consisted of two orthogonal metal gratings, which works as the patterned ground. The PIN diodes are embedded on both the upper and lower layer of the patterned ground and controlled through two independent sets of external DC bias network to achieve the multi-function. The gratings serve as both the resonant structure and the PIN diode biasing lines. Therefore, no additional feeding lines are introduced, which can decrease the impact on the performance of the MRPCM. When the PIN diodes of the two layers are turned on, the MRPCM will reflect and convert the incident wave into cross-polarization. When the PIN diodes of the two layers are turned off, the dual-polarization incident waves are transmitted through the MRPCM without conversion. If the PIN diodes of the two layers are in different state, the x - (OFF-ON) and y -polarized (ON-OFF) incident waves are transmitted and their E-field are rotated by 90°, respectively. Both numerical simulations and experimental results show good reconfigurable performance of the MRPCM.

A Fault Tolerant Control for Sensor and Actuator Failures of an Non Linear Hybrid System

<p>We focused in this work on a fault tolerant control of a non linear hybrid system class based on diagnosis method (determine and locate the defects and their types) and on the faults reconfiguration method.In literature we can found many important research activities over the fault-tolerant control of non linear systems and linear Hybridsystems. But it dosen´t exist too many for the non linear hybridsystem.The main idea in this paper is to consider a new approach to improve the reconfiguration performance of the non linear hybrid system by using hammerstein method which is designed to works only for linear systems. This method compensated the effect of the faults and guarantees the closed-loop system stable. The proposed method is simulated with a hydraulic system of two tanks with 4 modes.</p>

Kirigami metamaterials for reconfigurable toroidal circular dichroism

The ancient paper craft of kirigami has recently emerged as a potential tool for the design of functional materials. Inspired by the kirigami concept, we propose a class of kirigami-based metamaterials whose electromagnetic functionalities can be switched between nonchiral and chiral states by stretching the predesigned split-ring resonator array. Single-band, dual-band, and broadband circular polarizers with reconfigurable performance are experimentally demonstrated with maximum circular dichroism of 0.88, 0.94, and 0.92, respectively. The underlying mechanism is explained and calculated via detailed analysis of the excited multipoles, including the electric, magnetic, and toroidal dipoles and quadrupole. Our approach enables tailoring the electromagnetic functionalities in kirigami patterns and provides an alternate avenue for reconfigurable optical metadevices with exceptional mechanical properties.

NVM Streaker: a fast and reconfigurable performance simulator for non-volatile memory-based memory architecture

The high density, low power consumption non-volatile memory (NVM) provides a promising DRAM alternative for the in-memory big-data processing applications, e.g., Spark, It is significant to simulate the behaviors when NVMs are deployed into the area of big-data processing before their widespread use in market. However, existing simulation approaches are not applicable for big-data processing due to two reasons. First, some approaches require complicated hardware and/or OS supports. Second, cycle-level or function-level simulations are too time-consuming to simulate the whole software stack of big-data processing. Therefore, the complexity and expensive time cost in NVM simulation have dramatically dragged down the integrated research of big data with NVM. This paper proposes a fast and reconfigurable simulation method, called NVM Streaker, which does not need complex hardware or OS supports. It simulates NVM access costs using disturbed DRAM accesses and commonly configurable hardware parameters. It is fast since we use DRAM accesses and change its access costs to simulate NVM access costs, thus enabling to simulate the whole software stack to run Spark applications. It is reconfigurable since we enable users to configure the disturbed memory access costs, in order to simulate different NVM access costs. The experimental results show that we can simulate Spark applications with almost negligible cost and high efficiency.

Comparing the Performance of Reference Trajectory Management and Controller Reconfiguration in Attitude Fault Tolerant Control

Reference trajectory management is a method to modify reference trajectories for the faulty system. The modified reference trajectories define new maneuvers for the system to retain its pre-fault dynamic performance. Controller reconfiguration is another method to handle faults in the system, for instance by adjusting the controller parameters (coefficients). Both of these two methods have been considered in the literature and are proven to be capable of handling various faults. However, the comparison of these two methods has not been considered sufficiently. In this paper, a controller reconfiguration mechanism and a reference trajectory management are proposed for the spacecraft attitude fault tolerant control problem. Then, these two methods are compared under the same conditions, and it is shown that the proposed controller reconfiguration has better performance than the proposed reference trajectory management. The reason is that the controller reconfiguration has more variables to modify the closed-loop system behavior.

An efficient implementation of FPGA based high speed IPSec (AH/ESP) core

The IPSec is used to secure the IP traffic. The IPSec protocol was designed to fulfil the need to provide security at the network level, so that all the higher-layer protocols in the OSI model could take advantage of it. The implementation of IPSec is a computationally heavy task that affects the high speed network performance. To overcome this issue, the best possible solution is hardware implementation. For a hardware implementation the FPGA platform is considered as one of the best solutions because of its re-configurability and high performance capabilities. The work presented here gives a complete FPGA based implementation of IPSec. This includes both (AH and ESP) IPSec protocol formats. Both IPSec formats are implemented using transport mode and tunnel mode operations. IPSec is not bounded to use any specific cryptographic algorithms; here IPSec is used with the AES and SHA-3 algorithms to provide confidentiality and integrity services respectively.