Increase Fault Tolerance Research Articles

USING EXCESS CODE TO DESIGN FAULT-TOLERANT TOPOLOGIES

and in modernizing an already existing one. Particular attention is paid to it when building multicomputer systems or clusters. The most interesting ways to increase fault tolerance is to use the topological structure of the system to bypass the malfunction and use one or another element of the system to replace the faulty. Of course, this requires the development of a specific topology. The article deals with the development of fault-tolerant versions of popular topologies, such as quasiquantum and hypercube, based on the excess code 0/1 /-1. Target setting. An important part of any multicomputer system or cluster is its topological structure. This structure defines the routing of messages in the system, speed of message transmission, and level of fault-tolerance of a system. The article proposes a method for increasing fault-tolerance based on the use of excess code. Actual scientific researches and issues analysis. Synthesis of topologies such as the hypercube or the de Bruin topology is well studied and described now, there are papers consider methods for increasing the fault-tolerance that based on usage of additional nodes that duplicate current nodes. Other papers consider using a tree-based routing to improve fault-tolerance of the system. Uninvestigated parts of general matters defining. Now the possibilities of using excess code 0/1/-1 for creating new fault-tolerant topologies based on existing synthesis methods are unconsidered. The research objective. The task is to describe the synthesis of fault tolerant topologies, the consideration of the possibilities of using their features and the analysis of the main characteristics in comparison with each other and with classic versions based on binary code. The statement of basic materials. The synthesis of hypercube and de Bruin topology is described on the basis of the usual binary code and the redundant code 0/1 / -1, the possibilities of using redundancy are considered, first of all, to increase the fault-tolerance, a comparative analysis of all of these topologies is carried out. Conclusions. The analysis of characteristics is performed, the main advantages and disadvantages of the proposed topological structures are highlighted, suggestions for their improvement are made.

Campus Network Renewal to Increase Fault Tolerance and User Traceability

Campus Network Renewal to Increase Fault Tolerance and User Traceability

Grid services in a box: container management in ALICE

Virtualization and containers are established tools for providing simplified deployment, elasticity and workflow isolation. These benefits are especially advantageous in containers, which dispense with the resource overhead associated with virtual machines in cases where virtualization of the full hardware stack is not considered necessary. Containers are also simpler to setup and maintain in production environments–deployed and currently operational systems serving end-users, where service disruptions should be avoided. This contribution addresses container configuration and deployment to run central and site services on the ALICE Grid system, specifically to achieve containerized VO-boxes. We describe the methods through which we minimize the manual interaction, while retaining the simplicity and scalability associated with container deployment, the so-called ”service in a box”. Furthermore, we explore ways to increase fault tolerance, aimed at reducing the risk of service downtime, and identify possible performance bottlenecks.

Damage propagation in 2d beam lattices: 1. Uncertainty and assumptions

The paper studies damage propagation in brittle elastic beam lattices, using the quasistatic approach. The lattice is subjected to a remote tensile loading; the beams in the lattice are bent and stretched. An introduced initial flaw in a stressed lattice causes an overstress of neighboring beams. When one of the overstressed beams fails, it is eliminated from the lattice; then, the process repeats. When several beams are overstressed, one has to choose which beam to eliminate. The paper studies and compares damage propagation under various criteria of the elimination of the overstressed beams. These criteria account for the stress level, randomness of beams properties, and decay of strength due to micro-damage accumulation during the loading history. A numerical study is performed using discrete Fourier transform approach. We compare damage patterns in triangular stretch-dominated and hexagonal bending-dominated lattices. We discuss quantitative characterization of the damage pattern for different criteria. We find that the randomness in the beam stiffness increases fault tolerance, and we outline conditions restricting the most dangerous straight linear crack-like pattern.

VLSI AND SYSTEM-ON-CHIP REDUNDANT COMPONENTS SYNTHESIS

Redundancy - mostly used method to increase fault tolerance of the system. Fault tolerance in modern embedded systems is important feature due to accelerating aging and manufacturing defects, which diagnosis during the chip testing at fabric is impossible. In addition, different ways of system using may need different degree of fault tolerance. From Application Specified Integrated Circuit (ASIC) design point of view redundancy means area and power increasing. On early design stages, it is necessary to see the correlation between the components hardware description and its synthesized equivalent. The article considers several variants of synthesized redundant components that show the effect on area and power regarding to their architecture. The main goal of presented research is to describe RTL and Synthesis correlation.

White Rabbit HSR: A Seamless Subnanosecond Redundant Timing System With Low-Latency Data Capabilities for the Smart Grid

New smart grid and industrial-Internet-of-things (IIoT) directions require accurate synchronization features to capture, trigger, and manage events in industrial networks with the best possible precision and accuracy. The implementation of redundancy features for time and data distribution to increase fault tolerance, together with an enhancement of the availability of the network services such as generic object-oriented substation events, become mandatory due to their critical nature. For these reasons, the authors of this paper presented a new challenging approach covering the industrial standards requirements regarding timing and availability through the development of mechanisms that make possible the avoidance of single point of failure in ring topologies. This approach uses the White Rabbit (WR) as the main timing distribution technology, able to synchronize devices below 1 ns. Moreover, the development of a mechanism able to change from a primary to a backup time reference in approximately zero time with an observed maximum phase shift of 170 ps implies an important qualitative leap with respect to IIoT and the smart grid (e.g., phasor measurement units). This paper addresses the development and results of the high-availability seamless redundancy protocol for the WR technology to conform a leading-edge deterministic and reliable ultraaccurate timing system with high-availability data features for industrial facilities in accordance with IEC 61850 and IEC 62439-3.

Reliable real-time task scheduler based on Rocket Queue architecture

This paper presents the design of an improved task scheduler for real-time and safety-critical systems, where it is important to deal with real-time requirements and reliability requirements simultaneously. The proposed scheduler implements EDF algorithm for the optimal scheduling of hard real-time tasks, which is essential for real-time operating systems. The proposed task scheduler allows removing any task from the queue according to task ID and regardless of the actual position of the task within the queue, which is important for flexibility of the scheduler for its future extensions. Both operations of the scheduler, i.e. task adding and task killing take always constant time (two clock cycles) to execute regardless of the actual or the maximum number of tasks within the scheduler. The scheduler was verified using simplified version of UVM and applying millions of instructions with randomly generated sort values. The scheduler, implemented in a form of a coprocessor, was synthesized into Intel FPGA Cyclone V with 100MHz clock frequency. There are two improvements proposed that can significantly reduce resource costs of the scheduler, which is achieved by replacing static deadlines with dynamic deadlines and using a new Rocket Queue architecture for sorting of the tasks according to their deadline values. When both improvements are applied simultaneously, the total ALM cost savings are in the range from 42,59% to 60,18% and the total amount of registers is reduced by 73,74% to 74,87%, depending on the scheduler capacity. The spared resources are then used for implementation of two different variations of TMR in order to increase fault tolerance of the scheduler. The resource cost reductions achieved also indirectly increase the reliability of such scheduler because of reduced probability that a fault occurs.

Comparisons of Rare-Earth and Rare-Earth-Free External Rotor Permanent Magnet Assisted Synchronous Reluctance Motors

This paper presents the comparisons of five-phase external rotor permanent magnet assisted synchronous reluctance motors (PMa-SynRMs) with neodymium (Nd) and ferrite (Fe) based PMs. Five-phase PMa-SynRMs, in general, have been proposed as an alternative to conventional three-phase motors utilized in automobile applications. However, with increased attention towards higher torque density and lower torque pulsations in electric motor designs, five-phase external rotor PMa-SynRMs can be highly attractive. In addition to increased fault tolerance and reliability of five-phase PMa-SynRMs, an adaptation of external rotor design can significantly increase the average torque developed with reduced torque pulsations and back-electromotive force (EMF) harmonics. However, with the design complexity involved in such high performance five-phase PMa-SynRM designs, the shape of flux barrier and choice of PMs have been one of the main challenges. In this study, novel five-phase external rotor PMa-SynRM designs with optimal flux barrier number and shape with Nd and Fe PMs are presented. Finite element simulations are conducted on the 2-D designs to compare their performance characteristics such as torque developed, torque pulsations, structural stability, thermal heat flow, demagnetization effects, and back-EMF harmonics. Optimal 3.8 kW Nd-based and 3.7 kW Fe-based five-phase external rotor PMa-SynRM designs are fabricated, and experimental tests are conducted on the prototypes to compare the results with a benchmark internal rotor PMa-SynRM.

MooreCube: A Scalable and Flexible Architecture for Cloud Computing Data Centers on Multi-port Servers

Networks provide the infrastructure of cloud computing data centers. Servers in data centers grow to respond to the growing user demands. Data center scalability and flexibility in the use of multi-port servers is a challenging issue. Heretofore, no method has been considered for scalability and flexibility issues. This paper proposes a new architecture called MooreCube that can increase network scalability and decrease network diameter as well as increase flexibility. MooreCube is a scalable and flexible architecture that each multi-port server directly connected to other servers via bi-directional links, without using any switch. Furthermore, MooreCube is a recursively defined architecture that uses Moore graph as Building Block (BB) structure and uses the hierarchical structure to meet high scalability. The paper proposes a multipath routing to increase fault tolerance and decrease links burden. MooreCube architecture compared with other switchless architectures that use reserved ports to increase scalability. The simulation results show MooreCube increase scalability and flexibility along with decrease the diameter of the network.

Methods to Increase Fault Tolerance of Combinational Integrated Microcircuits by Redundancy Coding

Increasing the operating reliability of integrated microcircuits (IMC) remains, on the whole, an unsolved design problem. An important aspect of this problem is the stability of the circuits under transient faults (malfunctions) in large integrated circuits. Faults appear due to various disturbances: radiation, supply voltage jumps, signal degradation over time, etc. Investigations show that the probability of an error due to these factors may vary between very wide limits: from less than 0.1% for large circuits and up to 30% for very small circuits. In this article, we consider various methods of enhancing the fault tolerance of combinational circuits and also assess the effect of a single fault and a stuck-at fault on circuit operation for the case of combinational circuits from the ISCAS’85 set.

Linear Network Coding and Parallel Transmission Increase Fault Tolerance and Optical Reach

Modern optical network systems are evolving toward more spectral flexibility and efficiency driven by the ever-increasing need for high-speed transmission. In spectrally efficient elastic optical networks, a more integrated, fault tolerant transmission system is becoming critical, due to the accompanying optical impairments and the resulting limitations in optical reach. Previous work has addressed the issue of optical reach and transmission tolerance to faults (errors) in the physical layer by deploying various forward error correction schemes. This paper proposes a different approach, complementary to the error correction mechanisms in the physical layer. In our approach, we apply randomized linear network coding (RLNC) at the source node to encode all data in the electronic layer before all-optical transmission. To achieve fault tolerance, a coded auxiliary optical channel is used in parallel with the main path. With the auxiliary path and RLNC, as shown analytically, the system is able to use more advanced modulation formats in the main path, while being highly tolerant to bit errors and packet loss caused by optical impairments. The results show that the system can alleviate the constraints on optical transmission quality and achieve better optical reach and spectral efficiency.

Exploiting Idle Hardware to Provide Low Overhead Fault Tolerance for VLIW Processors

Because of technology scaling, the soft error rate has been increasing in digital circuits, which affects system reliability. Therefore, modern processors, including VLIW architectures, must have means to mitigate such effects to guarantee reliable computing. In this scenario, our work proposes three low overhead fault tolerance approaches based on instruction duplication with zero latency detection, which uses a rollback mechanism to correct soft errors in the pipelanes of a configurable VLIW processor. The first uses idle issue slots within a period of time to execute extra instructions considering distinct application phases. The second works at a finer grain, adaptively exploiting idle functional units at run-time. However, some applications present high instruction-level parallelism (ILP), so the ability to provide fault tolerance is reduced: less functional units will be idle, decreasing the number of potential duplicated instructions. The third approach attacks this issue by dynamically reducing ILP according to a configurable threshold, increasing fault tolerance at the cost of performance. While the first two approaches achieve significant fault coverage with minimal area and power overhead for applications with low ILP, the latter improves fault tolerance with low performance degradation. All approaches are evaluated considering area, performance, power dissipation, and error coverage.

METHOD OF INCREASING FAULT TOLERANCE OF SATELLITE COMMUNICATION NETWORKS UNDER INFORMATION TECHNOLOGY INTERFERENCE

Aim. The aim of the paper is to develop a method that would allow for integrated experimental, computational, analytical and expert assessment of the vulnerabilities of satellite communication networks, feasibility of information technology interference by intruders against such vulnerabilities and probability of fault tolerance under the chosen information protection solutions, trusted information technologies and fault tolerance sensors. The paper shows the relevance and importance of the method of increasing fault tolerance of satellite communication networks under information technology interference in service control channels and satellite equipment data. The authors examine targeted information technology interference that causes malfunction of satellite modems, control stations and connected user computer networks. The paper shows the unique nature of satellite communication networks operation due to the global operating range, availability of broadband radio signals from communication and retransmission spacecraft for technical analysis and processing within the operating range, potential possibility of unauthorized connection to communication services. The primary direction of development of procedural and process engineering guidelines on protection and fault tolerance of satellite communication networks are defined. Methods. A method has been developed that is based on three components: model of experimental identification of satellite communication network vulnerabilities; simulation, computational and analytical model of detection and identification of threats of information technology interference; decision-making algorithm for improvement of the fault tolerance of a satellite communication network under information technology interference. The model of experimental detection of satellite communication network vulnerability allows, as part of bench tests, establishing connections between existing vulnerabilities of the hardware and software of satellite modems, control stations, user networks and the potential information technology interferences by intruders. As part of the vulnerability model the authors describe the certificates of vulnerable radio technical and information technology parameters of the satellite communication network signals, as well as suggest an analytic expression for calculating the probability of detection of such network vulnerabilities. The paper presents a computational and analytical model of detection and identification of information technology interference threats as a structure of advanced means of detection, prevention and elimination of the consequences of information technology interference in satellite communication networks and the mathematical expression for identification of conditional probability of materialization of the threat of information technology interference in satellite communication networks. An algorithm is considered for improvement of fault tolerance of satellite communication networks under information technology interference, including preparation of parameters and evaluation of the fault tolerance of a satellite communication network, adjustment of the parameters of satellite communication network, information security facilities and fault tolerance sensors, situational adjustment of satellite communication network fault tolerance solutions. Conclusions. It is noted that the developed method enables improved fault tolerance of satellite communication networks under information technology interference based on a set of interconnected procedures of the model of experimental detection of satellite communication network vulnerabilities on testbed; simulation, computational and analytical models of detection and identification of information technology interference threats; application of the decision-making algorithm of improvement of satellite communication network fault tolerance.

Principles of Organization and Operation of an Unmanned Robotic Production with a Decentralized Controller

This work is devoted to the topical problem of elaboration of new principles of a decentralized cooperation of the computer systems, which will create a new class of unmanned robotic productions (URP). In the shortest possible time they could produce a variety of prototypes and individual items meeting the remote customers' requirements. Use of the principles of decentralized multiagent scheduling of URP ensures: firstly, high availability of the system, because it lacks the 'bottleneck" in the form of a central controller, and a failure of any of the agents does not lead to the catastrophic consequences for the entire URP; secondly, a possibility of virtually unlimited increase of the number of nodes as a part of URP because of an easy connectivity to the information communication channel; and, finally, thirdly, a reduction of the computational load on an individual software agent in the solution of the scheduling tasks, which in turn, makes it possible to get solutions in real time. This article describes the generic principles of organization and functioning of the unmanned robotic productions with a decentralized controller. Implementation of these principles ensures: - a possibility of automation of the approach to the flow of tasks of production of various products coming from customers in advance and in unknown times; - an adaptive quasi-optimal allocation of resources based on their expertise in the real-time of receipt of the assignments; - a high payload operation of the nodes in the URP; - a possibility of unlimited scalability; - an increased fault tolerance, since it lacks components, the failure of which could lead to a failure of the entire system.

Baseline Parametric Survey on Causes of Traffic Congestion in Datacenter Networks

Distributed cloud datacenters are currently used as deployment environment for large-scale web-facing enterprise analytic cloud applications. In the era of cloud computing, these networks allow unprecedented scalability in response to dynamic and unpredictable grid workloads. However, grid applications need to scale beyond the limits of single-tenanted datacenter to multi-tenanted datacenter sites providing regulatory service level compliance, efficient Quality of Service (QoS) and increased fault tolerance at all times. Following the complex hierarchical design structure of emerging cloud networks such as Internet of Things (IoT) and Fog Computing Networks (FCNs), congestion crisis becomes a critical consideration for future expansion of these networks. This paper carried out a Baseline Parametric Survey (BPS) to ascertain major factors of DCN traffic congestion in selected production networks in Nigeria. From the survey, it was observed that the absence of an intelligent load balancer, bandwidth size, network traffic type, and network switch butter capacity, number of users on the network, segmentation and routing devices all contribute to network congestion incidence. The deductions from this work can be used to implement a Fog internet layer for smarter data off-loading in today’s internet of everything.

Regulations and latency-aware load distribution of web applications in Multi-Clouds

Cloud data centres have become the preferred hosting environment for large-scale web-facing applications. They allow unprecedented scalability in response to a dynamic and unpredictable workload. However, many applications need to scale beyond the boundaries of a single data centre to multiple geographically dispersed clouds sites (i.e. a Multi-Cloud) to provide regulatory compliance, better Quality of Experience (QoE) and increased fault tolerance. In this work, we introduce a flexible framework which allows interactive web applications to utilise a Multi-Cloud environment. It redirects users to suitable cloud sites considering the latency and regulatory constraints. Regulatory requirements are specified via a flexible and simple domain-specific model, which is then interpreted by a rule inference engine. We conducted an experimental evaluation of the proposed system using services of ten cloud sites/data centres located in five continents and offered by two cloud providers, namely Amazon and NeCTAR. The results show that our approach minimises latency, is fault tolerant, and meets all stated regulatory requirements with negligible performance overhead.

Winding Configurations for Five-Phase Synchronous Generators With Diode Rectifiers

Wound-field synchronous generators are widely used in aircraft and marine electrical systems. As the electric power requirements increase, there is renewed interest in dc power networks, but the electrical source remains a synchronous generator. The combination of a diode rectifier with a wound-field multiphase generator reduces the voltage ripple on the dc network and increases fault tolerance, compared with an equivalent three-phase system. It also increases the options in terms of the winding design and configuration. This paper uses circuit modeling, including harmonics, informed by static finite-element results, to understand the wound-field generator performance for star and polygon connections of both short- and fully-pitched coils. Experimental results are used to validate the models. A polygon connection of short-pitched coils is shown to give good generator utilization for a healthy machine. However, careful design is required to prevent circulating harmonic currents. Under winding open-circuit faults, the polygon connection requires significant derating, making the star connection the preferred option.

Electromagnetic Design and Analysis of a Novel Fault-Tolerant Flux-Modulated Memory Machine

Electric machines play an important role in modern energy conversion systems. This paper presents a novel brushless fault-tolerant flux-modulated memory (FTFM) machine, which incorporates the merits of a flux-modulated permanent magnet machine and multi-phase memory machine and is very suitable for applications that require wide speed ranges of constant-power operation. Due to the magnetic modulation effect, the FTFM machine can produce a large torque at relatively low speeds. Due to the usage of aluminum-nickel-cobalt (AlNiCo) magnets, this machine can readily achieve a flexible air-gap flux controllability with temporary DC current pulses. Consequently, the constant-power region is effectively expanded, and the machine\'s efficiency during constant-power operation is increased. Due to the multi-phase armature winding design, the FTFM machine enables lower torque ripple, increased fault tolerance ability and a higher possibility of splitting the machine power through a higher number of phases, thus the per-phase converter rating can be reduced. The design methodology and working principle of this kind of machine are discussed. The electromagnetic performances of the proposed machine are analyzed using the time-stepping finite element method (TS-FEM).

Review on Fault Tolerance Techniques in Cloud Computing

With the immense growth of internet and its users, Cloud computing, with its incredible possibilities in ease, Quality of service and on-interest administrations, has turned into a guaranteeing figuring stage for both business and nonbusiness computation customers. It is an adoptable technology as it provides integration of software and resources which are dynamically scalable. The dynamic environment of cloud results in various unexpected faults and failures. The ability of a system to react gracefully to an unexpected equipment or programming malfunction is known as fault tolerance. In order to achieve robustness and dependability in cloud computing, failure should be assessed and handled effectively. Various fault detection methods and architectural models have been proposed to increase fault tolerance ability of cloud. The objective of this paper is to propose an algorithm using Artificial Neural Network for fault detection which will overcome the gaps of previously implemented algorithms and provide a fault tolerant model.

An overnight habitat for expanding lunar surface exploration

This paper presents the conceptual design and analysis of a system intended to increase the range, scientific capability, and safety of manned lunar surface exploration, requiring only a modest increase in capability over the Apollo mission designs. The system is intended to enable two astronauts, exploring with an unpressurized rover, to remove their space suits for an 8-h rest away from the lunar base and then conduct a second day of surface exploration before returning to base. This system is composed of an Environmental Control and Life Support System on the rover, an inflatable habitat, a solar shield and a solar power array. The proposed system doubles the distance reachable from the lunar base, thus increasing the area available for science and exploration by a factor of four. In addition to increasing mission capability, the proposed system also increases fault tolerance with an emergency inflatable structure and additional consumables to mitigate a wide range of suit or rover failures. The mass, volume, and power analyses of each subsystem are integrated to generate a total system mass of 124kg and a volume of 594L, both of which can be accommodated on the Apollo Lunar Roving Vehicle with minor improvements.