Redundant Configuration Research Articles

Data Security of Dynamic and Robust Role Based Access Control from Multiple Authorities in Cloud Environment

Abstract: Data integrity maintenance is the major objective in cloud storage. It includes audition using TTP for unauthorized access. This work implements protecting the data and regeneration of data if someone mishandles it. This job will be assigned to a Proxy server. The data of the users will be stored in public and private area of the cloud. So that only public cloud data will be accessed by user and private cloud will remain more secured. Once any unauthorized modification is made, the original data in the private cloud will be retrieved by the Proxy server and will be returned to the user. Cloud storage generally provides different redundancy configuration to users in order to maintain the desired balance between performance and fault tolerance. Data availability is critical in distributed storage systems, especially when node failures are prevalent in real life. This research work explores secure data storage and sharing using proposed AES 128 encryption algorithm and Role Base Access Control (RBAC) for secure data access scheme for end user. This work also carried out backup server approach it works like proxy storage server for ad hoc data recovery for all distributed data servers. The experiment analysis has proposed in public as well as private cloud environment. Keywords: RBAC, Elgamal encryption scheme; secure user access policy; Proxy Key Generation, Role Base Access Control (RBAC), advanced encryption standard (AES), etc.

Simulation Study of Reliability Model and Optimization for Electrical Power System

Abstract An architecture with multi-parallel and multi-standby system of aircraft electrical power system is proposed, simulation study is given. First the reliability model of parallel system is formulated, and total system reliability model is obtained. Parallel subsystem number and standby subsystems number are the two parameters of reliability model. In order to maximize the system MTBF and minimize the purchase cost of each subsystem, a novel redundancy optimization function is proposed. Simulation results are analyzed to study the impact of parameters on the system reliability. Redundancy number and configuration of typical aircraft power system is also discussed from the viewpoint of application practice. Simulation result shows that the architecture is flexible, with the options to increase or decrease subsystems of parallel or standby systems to satisfy reliability and capacity requirement.

GPU-Accelerated Online Short-Circuit Interrupting Capacity Scan Based on Unified Modeling

With the increasing of transmission density and short-circuit current level, interruption capacity scanning has become an important approach for the online assessment of the circuit breaker. The short-circuit calculation scale and the expected failures significantly increase under the demand of unified analysis of the whole grid, which cause the considerable challenges for online assessment. In this study, we propose a GPU-accelerated short-circuit interruption capacity scanning algorithm for two different unified models, that is, GPU-based 2D and 3D expansion models. For both models, the redundant configuration of the fault network matrices is designed to reduce the cost of GPU computation process. Then, the batch node voltage analysis and the batch branch current calculation are derived using the considered model. In addition, the differences between two models are discussed in detail. Simulations show that the proposed algorithm with GPU-based 3D-expand model has a 3.45× speedup compared with the traditional algorithm on a 9241-bus system with 8-core CPU. Therefore, the proposed algorithms have the potential to handle the full short-circuit current scan under the unified analysis scenario.

Research on Improving Heading and Attitudes Accuracy by Online Calibration of Errors Based on Multi-RINSs Joint Rotation Modulation

The ship usually adopts multiple sets of rotational modulation inertial navigation system (RINS) to ensure the accuracy and reliability of long endurance navigation, but the rotational modulation will excite the gyro installation error and scale factor error, which will cause periodic oscillation of navigation attitude information, moreover, due to the influence of temperature, vibration and other environments, these errors will change in the results of pre-calibration, and it is impossible to accurately model them, resulting in the further aggravation of attitudes oscillation, which is not conducive to the transfer alignment between master and slave INS. However, the ship is always swinging or maneuvering, a single RINS can not complete self-calibration independently in dynamic condition. In order to solve the above problems, in this paper, an online calibration algorithm based on joint rotation modulation of multi-RINSs is proposed for redundant configuration of multi-RINSs without extra conditions, and the error parameters are tracked and estimated every 4 minutes, the dynamic simulation results show that the calibration strategy can effectively calibrate the gyro installation error, the nonorthogonal angle between the gimbals and the scale factor error of the z-gyro of each RINS, which proves the correctness of the calibration strategy. The results of 3h navigation experiment show that the amplitude of attitudes oscillation decreases about 80% after the compensation of joint calibration error parameters, the fluctuation amplitude of heading angle decreases by 70%, the effectiveness of the calibration strategy in practical application is further verified, the relationship of ship multi-RINSs changes from backup to assistance, which is of great significance to improve the heading and attitudes accuracy of RINSs and the transfer alignment performance between master and slave INS.

Reliability-Oriented Configuration Optimization of More Electrical Control Systems

More electrical vehicles adopt dissimilar redundant control systems with dissimilar power supplies and dissimilar actuators to achieve high reliability and safety, but this introduces more intricacy into the configuration design. Currently, it is difficult to identify the optimum configuration via the conventional trial-and-error approach within an acceptable timeframe. Hence, it is imperative to discover novel methods for the configuration design of more electrical vehicles. This paper introduced the design specification of more electric vehicles and investigated the contribution of different kinds of actuators, presenting a new multi-objective configuration optimization approach on the foundation of system reliability, weight, power, and cost. By adopting the non-dominated sorting genetic algorithm-II (NSGA-II), the Pareto optimization design set was obtained. Then, the analytic hierarchy process (AHP) was introduced to make a comprehensive decision on the schemes in the Pareto set and determine the optimal system configuration. Eventually, numerical results indicated that the reliability of our designed configuration increased by 5.89% and 55.34%, respectively, compared with dual redundancies and single redundancy configurations, which verified the effectiveness and practicability of the proposed method.

Hybrid MMC Redundancy Configuration Calculation Method Based on Heuristic Algorithm

Most of the existing redundant configuration methods of modular level converters (MMC) only consider the reliability of the MMC, and rarely consider the utilization of insulated gate bipolar transistors (IGBT). A heuristic algorithm-based calculation method for hybrid MMC redundancy configuration is proposed in order to better meet the engineering practicality. Firstly, the topology of the hybrid MMC is introduced, and the correlation between submodules is introduced into the calculation of its reliability. Secondly, the index of IGBT utilization is proposed to judge the economic advantage. The effects of correlation and service life on the reliability of the hybrid MMC and the IGBT utilization are analyzed. Then, heuristic factors are constructed with reliability and IGBT utilization, and the optimal redundancy configuration scheme of hybrid MMC is obtained by heuristic algorithm. Finally, based on the parameters of Kunliulong multi-terminal hybrid DC transmission project, the calculation is verified in Matlab and compared with the results of the difference method to illustrate the feasibility and superiority of the proposed redundancy configuration calculation method.

Computer Simulation Research of Self-adaptive Compensation Control Based on Neural Network for Control Surface Failure of Uncertain Tailless Flying Wing Aircraft

The conventional aircraft layout will contain the elevator, aileron, rudder three control surfaces, and thus generate three control moments to adjust the aircraft trajectory and flight attitude. However, the aircraft with multi-control plane flying wing layout needs to choose redundant new control plane configuration, which is quite different from the conventional aircraft layout in both control method and operation mode. Since there are many problems in the aircraft motion mathematical model during the ownership period, which will directly affect the control effect of the flight control system, in order to reduce dynamic error and improve the robustness and accuracy of the flight control system, this paper proposes an adaptive neural network algorithm. Combined with the current operating status of tailless flying wing aircraft and the research status of aircraft control system analysis, this paper mainly discusses the design differences between the adaptive control system and the original control system, based on the empirical case, to clarify the compensation effect of the adaptive control system.

North Celestial Region Observed with 21 CentiMeter Array

The 21 CentiMeter Array (21CMA) is a radio interferometer in western China. The key science objective of 21CMA is statistically measuring the redshifted H i 21 cm signal of the Epoch of Reionization (EoR). In order to achieve this, a catalog of radio sources is necessary for both calibration and foreground removal. In this work, we present a catalog of 832 radio sources within a radius of 5° around the North Celestial Pole region observed with 21CMA. Three days of data taken in 2013 are used in the analysis, with a frequency coverage from 75 to 200 MHz and an angular resolution of about two arcminutes at 200 MHz. Flux densities and estimated spectral indices of the radio sources are provided in the source catalog. For simplicity, only the east–west baseline is used for the observations to avoid the so-called w − term in the data analysis. The longest baseline along the east–west direction is 2780 m. Comparing our source counts with other radio observations, we find a good agreement with the observations made with the Giant Metrewave Radio Telescope and Murchison Widefield Array. Our data reduction is still limited by grating lobes of very bright sources in the field due to the redundant configuration of 21CMA. We note that understanding the properties of radio sources, and modeling and removing the radio sources are challenges for the EoR experiments.

A Model Predictive Control for Path Tracking of Electronic-Four-Wheel Drive Vehicles

This paper proposes a path tracking controller to assist the electronic-four-wheel drive (e-4WD) vehicle in following the desired path profile. It utilizes only readily available in-vehicle sensors and a standalone global positioning system (GPS). Noteworthy, both the lateral distance error and the heading angle error between the desired path profile and the vehicle are calculated using only a standalone GPS. Therefore, the proposed algorithm can be easily applied to mass-produced e-4WD vehicles. A model predictive control (MPC) is selected as the controller type, which derives optimal control input considering both state and input constraints of in-wheel motor (IWM) in the e-4WD vehicle. Due to the advantage of this MPC predicting the vehicle's future dynamic behavior in advance, it is possible to output a more preemptive and stable yaw moment for vehicle path tracking. Finally, a weighted least square (WLS) allocation that is suitable for redundant actuator configuration is utilized to distribute the optimal IWM torques to the front left and right wheels of the e-4WD vehicle. The major contributions of the proposed control algorithm are as follows. 1) It is the first time in this paper that the MPC is applied to path tracking of e-4WD vehicles. 2) The condensed constraint matrix of the proposed MPC has a structure that can be easily applied to the linear programming. Using the CarSim simulation and the real-car based experiment, the effectiveness of the proposed MPC algorithm is verified by a comparative analysis. Thus, the high path tracking accuracy of the proposed algorithm is confirmed.

Reliability analysis based on dynamic Bayesian networks: A case study of an unmanned surface vessel

Unmanned surface vessels (USVs) have been widely used in various activities to date. Reliability is particularly significant for USVs because of the increasing complexity of USV tasks and their characteristic that cannot be repaired during task execution. This study aims to analyse the reliability of USVs' overall system for providing an optimisation reference for their reliability improvement in the design phase. The method for modelling and analysing the reliability of complex systems based on Dynamic Bayesian Networks (DBNs) is studied. The reliability of a USV for seafloor topography survey is analysed. The reliability model of the USV overall system is established by mapping the Dynamic Fault Trees (DFTs) into DBNs considering the system logical structure, redundant configuration and dynamic behaviour. Reliability analysis, including reliability evaluation, importance measure and sensitivity analysis, are conducted on the basis of DBN inference. The overall reliability parameters of the USV are obtained to determine the critical subsystem and components. This research may provide a reference for the reliability design and optimisation of USVs.

MobileRE: A replicas prioritized hybrid fault tolerance strategy for mobile distributed system

Fault tolerance techniques are of vital importance to promise data reliability for mobile distributed system. In mobile environments, nodes suffer from high failure probability and fluctuating bandwidth. Thus, traditional fault tolerance techniques are no longer suitable. In this paper, we present a replica prioritized hybrid fault tolerance strategy combining erasure codes and replicas for a mobile distributed system (MobileRE), to guarantee data reliability with dynamic network status. In MobileRE, we first formulate a reliability cost rate to indicate the cost of ensuring data reliability of the mobile system. MobileRE further adaptively applies the erasure codes and replicas algorithms based on real-time network bandwidth status to minimize system reliability cost rate. MobileRE also obtains the optimal reliability cost rate by customizing redundant configuration parameters. The numerical and simulation results verify the effectiveness of the proposed schemes, and show that compared with traditional designs that only adopt erasure codes or replicas, MobileRE can significantly reduce the system reliability cost rate.

Research on Redundant Design Technique for USV Autonomous Control System

In the field of USV autonomous control system design, redundant design technology is the important method to improve system reliability. In order to solve the problem of insufficient reliability when USV carrying out long endurance and open sea task, this paper analyzes the critical design elements of autonomous control system redundant configuration, presents a high reliable hybrid redundant structure for USV autonomous control system, and realizes redundant strategy and fault-tolerant control. This paper forms the USV autonomous control system redundant configuration scheme comply with the fault-tolerant capability and redundant rank of USV autonomous control system. Redundancy management strategies and algorithms are used to implement USV autonomous control based on hybrid redundant design. The reliability analysis and computation validate task reliability of the autonomous control system based on hybrid redundant structure.

A Redundant Configuration of Four Low-Cost GNSS-RTK Receivers for Reliable Estimation of Vehicular Position and Posture.

This paper proposes a low-cost sensor system composed of four GNSS-RTK receivers to obtain accurate position and posture estimations for a vehicle in real-time. The four antennas of the receivers are placed so that every three-antennas combination is optimal to get the most precise 3D coordinates with respect to a global reference system. The redundancy provided by the fourth receiver allows to improve estimations even more and to maintain accuracy when one of the receivers fails. A mini computer with the Robotic Operating System is responsible for merging all the available measurements reliably. Successful experiments have been carried out with a ground rover on irregular terrain. Angular estimates similar to those of a high-performance IMU have been achieved in dynamic tests.

IoT-Enabled Wireless Sensor Networks for Air Pollution Monitoring with Extended Fractional-Order Kalman Filtering.

This paper presents the development of high-performance wireless sensor networks for local monitoring of air pollution. The proposed system, enabled by the Internet of Things (IoT), is based on low-cost sensors collocated in a redundant configuration for collecting and transferring air quality data. Reliability and accuracy of the monitoring system are enhanced by using extended fractional-order Kalman filtering (EFKF) for data assimilation and recovery of the missing information. Its effectiveness is verified through monitoring particulate matters at a suburban site during the wildfire season 2019–2020 and the Coronavirus disease 2019 (COVID-19) lockdown period. The proposed approach is of interest to achieve microclimate responsiveness in a local area.

Performance Enhancement of Consumer-Grade MEMS Sensors through Geometrical Redundancy.

The paper deals with performance enhancement of low-cost, consumer-grade inertial sensors realized by means of Micro Electro-Mechanical Systems (MEMS) technology. Focusing their attention on the reduction of bias instability and random walk-driven drift of cost-effective MEMS accelerometers and gyroscopes, the authors hereinafter propose a suitable method, based on a redundant configuration and complemented with a proper measurement procedure, to improve the performance of low-cost, consumer-grade MEMS sensors. The performance of the method is assessed by means of an adequate prototype and compared with that assured by a commercial, expensive, tactical-grade MEMS inertial measurement unit, taken as reference. Obtained results highlight the promising reliability and efficacy of the method in estimating position, velocity, and attitude of vehicles; in particular, bias instability and random walk reduction greater than 25% is, in fact, experienced. Moreover, differences as low as 0.025 rad and 0.89 m are obtained when comparing position and attitude estimates provided by the prototype and those granted by the tactical-grade MEMS IMU.

Reconfigurable Slip Vectoring Control in Four In-Wheel Drive Electric Vehicles

Controllability, maneuverability, fault-tolerance/isolation and safety are significantly enhanced in electric vehicles (EV) equipped with the redundant actuator configuration of four-in-wheel electric motors (4IWM). A highly reconfigurable architecture is proposed and illustrated for the adaptive, nonmodel-based control of 4IWM-EVs. Given the longitudinal force, yaw-moment requests and the reconfiguration matrix, each IWM is given a slip reference according to a Slip Vectoring (SV) allocation strategy, which minimizes the overall slip vector norm. The distributed electric propulsion and the slip vector reference allow for a decentralized online estimation of the four-wheel torque-loads, which are uncertain depending on loading and road conditions. This allows for the allocation of four different torques depending on individual wheel conditions and to determine in which region (linear/nonsaturated or nonlinear/saturated) of the torque/slip characteristics each wheel is operating. Consequently, the 4IWMs can be equalized or reconfigured, including actuator fault-isolation as a special case, so that they are enforced to operate within the linear tire region. The initial driving-mode selection can be automatically adjusted and restored among eighteen configurations to meet the safety requirements of linear torque/slip behavior. Three CarSim realistic simulations illustrate the equalization algorithm, the quick fault-isolation capabilities and the importance of a continuous differential action in a critical double-lane-change maneuver.

Analysis of optimized multilevel matrix converter for DFIG based wind energy conversion system

Wind power generation is an increasing trend worldwide. Multilevel converters in this regard are playing an essential role in high power system applications due to various features. In this paper, multi-objective optimization based multilevel matrix converter (MOMMC) is proposed for wind energy conversion system. The assessment of feasibility through the discussion of two objectives: reliability and cost have been considered in this study. Initially, the model of the two objectives is assessed against redundancy configuration and power loss. Then a multi-objective function is defined for achieving low cost and high reliability. The optimal topology for the matrix multi-level converter is determined using the membership function, and the solution is selected from the Pareto-optimal set. The reliability and cost analysis of the proposed MOMMC is performed. Simulation is carried out for the proposed multi-objective optimization based multilevel matrix converter using the PSIM software. To establish the validity of the proposed method, two different cases: 1) fixed and 2) variable speed of 9 MW doubly-fed induction generator-based wind energy system are considered. The results show the superiority of the proposed method over the others .

NMR configurations with novel majority voter circuits to mask multiple module faults

Mission, safety, and business-critical applications need uninterrupted operation with correct results. But due to the technology shrinking, the microelectronic circuits can be affected by many faults like permanent, transient, and intermittent. So, there is a considerable demand for designing fault-tolerant systems. Hardware redundancy configurations have been widely used to protect or mask faults. In this research article, to mask multiple faults, N-modular redundancy (NMR) configurations are deployed, namely 5-MR and 7-MR configurations, which are implemented to mask two and three function module errors. Two majority voter (MV) circuits with 5-MR and 7-MR have been proposed, respectively. Simulation results are obtained with Application-Specific Integrated Circuits (ASIC) and Field Programmable Gate Arrays (FPGA). With ASIC, 120 nm technology is used with BSIM4 Spice simulation parameters. Also, the majority voters are evaluated with a band-pass filter as the function module on Altera DE2-115 FPGA using the Quartus II synthesis tool. The very high-speed integrated circuits hardware description language is used with FPGA implementation. Simulation results reveal that the proposed MV circuits obtain better results than the existing methods.

Super-Twisting Sliding Mode Control Law Design for Attitude Tracking Task of a Spacecraft via Reaction Wheels

The attitude control has been recognized as one of the most important research topics for spacecraft. If the desired attitude trajectory cannot be tracked precisely, it may cause mission failures. In the real space mission environment, the unknown external perturbations, for example, atmospheric drag and solar radiation, should be taken into consideration. Such external perturbations could deviate the precision of the spacecraft orientation and thereby lead to a mission failure. Therefore, in this paper, a quaternion-based super-twisting sliding mode robust control law for the spacecraft attitude tracking is developed. The finite time stability based on the formulation of the linear matrix inequality (LMI) is also provided. To avoid losing the control degree of freedom due to the certain actuator fault, a redundant reaction wheels configuration is adopted. The actuators distribution associated force distribution matrix (FDM) is analyzed in detail. Finally, the reference tangent-normal-binormal (TNB) command generation strategy is implemented for simulating the scenario of the space mission. Finally, the simulation results reveal that the spacecraft can achieve the desired attitude trajectory tracking demands in the presence of the time-varying external disturbances.

The Ariel Instrument Control Unit

Ariel, the Atmospheric Remote-sensing Infrared Exoplanet Large-survey mission (Tinetti 2019; Puig et al. 2018; Pascale et al. 2018), has been selected in March 2018 by ESA for the fourth medium-class mission (M4) launch opportunity of the Cosmic Vision Program, with an expected lift off in late 2028. It is the first mission dedicated to measuring the chemical composition and thermal structures of the atmospheres of hundreds of transiting exoplanets, enabling planetary science far beyond the boundaries of our own Solar System. Its Payload (P/L) (Eccleston and Tinetti 2018; Eccleston et al. 2017; Middleton et al. 2019), has been designed to perform transit spectroscopy from space during primary and secondary planetary eclipses in order to achieve a large unbiased survey concerning the nature of exoplanets atmospheres and their interiors, to determine the key factors affecting the formation and evolution of planetary systems (Tinetti et al. 2017, 2018). Ariel will observe hundreds of warm and hot transiting gas giants, Neptunes and super-Earths around a wide range of host star types, targeting planets hotter than $\sim $ 600 K to take advantage of their well-mixed atmospheres. It will exploit primary and secondary transit spectroscopy in the 1.10 to 7.80 μm spectral range and broad-band photometry in the optical (0.50 - 0.80 μm) and Near IR (0.80 - 1.10 μm) . One of the two instruments of the Ariel Payload is the Fine Guidance System (FGS), including three photometric channels (two used for guiding as well as science) between 0.5-1.1 μm plus a low resolution NIR spectrometer for 1.1-1.95 μm range. Along with FGS an IR Spectrometer (AIRS) (Amiaux et al. 2017) is foreseen, providing low-resolution spectroscopy in two IR channels: Channel 0 (CH0) for the 1.95 − 3.90 μm band and Channel 1 (CH1) for the 3.90 − 7.80 μm range. Finally, an Active Cooler System (ACS) including a Ne Joule-Thomson cooler is adopted to provide active cooling capability to the AIRS detectors working at cryogenic temperatures. AIRS is located at the intermediate focal plane of the telescope and common optical system and it hosts two HgCdTe-based hybrid IR detectors and two cold front-end electronics (CFEE) for detectors control and readout. Each CFEE is driven by a Detector Control Unit (DCU) part of AIRS but hosted within and managed by the Instrument Control Unit (ICU) of the Payload (Focardi et al. 2018). ICU is a warm unit residing into the S/C Service Module (SVM) and it is based on a cold redundant configuration involving the Power Supply Unit (PSU) and the Commanding and Data Processing Unit (CDPU) boards; both DCUs are instead cross-strapped and can be managed by the nominal or the redundant (PSU+CDPU) chain. ICU is in charge of AIRS management, collecting scientific and housekeeping (HK) telemetries from the spectrometer and HK from the telescope (temperatures readings), the P/L Optical Bench (OB) and other Subsystems (SS), thanks to a warm slave unit (TCU, Telescope Control Unit) interfaced to the ICU. Science and HK telemetries are then forwarded to the S/C, for temporary storage, before sending them to Ground. Here we describe the status of the ICU design at the end of B1 Phase, prior to the Mission Adoption Review (MAR) by ESA, with some still open architectural choices to be addressed and finalised once selected the ICU industrial Prime contractor.