Redundancy Options Research Articles

Research on a Covert Communication Model Realized by Using Smart Contracts in Blockchain Environment

The traditional covert communication channel relying on a third-party node is vulnerable to attack. The data are easily tampered with and the identity information of the communication party is fragile. Blockchain has the characteristics of decentralization and tamper resistance, which can effectively solve the above problems. In addition, some confidential information needs to be transmitted covertly in the transparent blockchain. A smart contract deployed in the blockchain to automatically realize its function can replace a centralized node to provide credible guarantee for communication. The diversity of parameters, data redundancy, and code programmability of smart contract make it an excellent carrier for covert communication under blockchain. In this article, we propose a covert communication model combined with smart contracts to covertly transfer information in the blockchain environment. To implement this model, we use the parameters in the contract to map the secret information sequence, and call the contract to transfer message. Voting contract and secret bidding contract are combined to instantiate the proposed model, and optimized versions of the two contracts are also proposed to reduce costs. Moreover, we use encryption algorithms and two-round protocols to ensure data privacy and design corresponding information embedding and transmission methods for different scenarios. To improve the concealment of communication, redundant options, effective price ranges, and invalid bids are set in two contracts, respectively. The experimental results show that the proposed model has tamper resistance and low complexity, and it is feasible to use this model for covert communication.

A Semantic Web-based Representation of Human-logical Inference for Solving Bongard Problems

Bongard Problems (BPs) are a set of 100 visual puzzles introduced by M. M. Bongard in the mid-1960s. BPs have been established as benchmark puzzles for understanding the human context-based learning abilities to solve ill- posed problems. The puzzle requires the logical explanation as the answer to distinct two classes of figures from redundant options, which can be obtained by a thinking process to alternatively change the target frame (hierarchical level of analogy) of thinking from a wide range concept networks as D. R. Hofstadter suggested. Some minor research results to solve a limited set of BPs have reported based a single architecture accompanied with probabilistic approaches; however the central problem on BP's difficulties is the requirement of flexible changes of the target frame, therefore non-hierarchical cluster analyses does not provide the essential solution and hierarchical probabilistic models needs to include unnecessary levels for learning from the beginning to prevent a prompt decision making. We hypothesized that logical reasoning process with limited numbers of meta-data descriptions realizes the sophisticated and prompt decision-making and the performance is validated by using BPs. In this study, a semantic web-based hierarchical model to solve BPs was proposed as the minimum and transparent system to mimic human-logical inference process in solving of BPs by using the Description Logic (DL) with assertions on concepts (TBox) and individuals (ABox). Our results demonstrated that the proposed model not only provided individual solutions as a BP solver, but also proved the correctness of Hofstadter's idea as the flexible frame with concept networks for BPs in our actual implementation, which no one has ever achieved. This fact will open the new horizon for theories for designing of logical reasoning systems especially for critical judgments and serious decision-making as expert humans do in a transparent and descriptive way of why they judged in that manner.

Over Pressure Risk Mitigation with SCADA in a Natural Gas Distribution System

Natural gas distribution providers have periodic and reactive maintenance plans that are not providing enough feedback and data to establish proper predictive analysis for failure, especially on distribution gas regulator station that are regulating gas from transmission pressure to a safe customer distribution pressure, these stations are the only overpressure safeguard and the highest risk at the same time. With the recent advances in computer and telecommunications technologies, some major gas utilities initiated more robust predictive risk analysis plans by introducing SCADA supervisory control and data acquisition to gas distribution, mainly monitoring gas regulator stations and their behavior based on their established overpressure prevention philosophies and long-term predictive analysis goals. This study outlines a full SCADA monitoring solution on a dual run gas distribution regulator station equipped with primary overpressure protection and redundancy options. RTU (Remote Terminal Units) containing flow and pressure monitoring transmitters are installed at specific pressure reduction points in the station piping. Unlike common monitoring practice, we are introducing mid-stream pressure monitoring between the monitor and regular valves, filter differential and flow measurement in our proposed SCADA set up. This system provides real time visibility and data to the gas control room to quickly recognize abnormal or emergency events and assess the current health of regulator equipment. The outlined risk mitigations in this study are created based on identified risks of overpressure under several regulation failure modes of the regulators in standby and working modes. Our SCADA solution introduces means to enhance deductive analysis and predictability for gas control departments and monitoring groups leading to a safer and more reliable gas distribution system, improving emergency response and creating more comprehensive maintenance plans driven by long term predictive risk plans.

INVESTIGATION OF A HYBRID REDUNDANCY IN THE FAULTTOLERANT SYSTEMS

Context. Structural redundancy is one of the main ways to create highly reliable devices and systems for critical applications. The object of the study was hybrid redundancy in the Fault-Tolerant Systems, for example in aerospace hardware exposed to radiation. Objective. The goal of the work is the calculation of the complexity and probability of failure-free operation of digital circuits with hybrid redundancy combining tripling, deep tripling, and quadding. The comparison shows that tripling is not always better than a circuit without redundancy over a sufficiently large time interval. Good results are obtained by tripling with three majority voters and deep tripling, but the latter significantly increases the time delay of the signal. The greatest gain in reliability provides quadding at the transistors level, but it is not always possible due to the restrictions of Mead-Conway, in addition, the delay at least is doubled. The article describes proposed method of the combined redundancy taking into account the necessary hardware costs and time delay. Method. Determining the complexity in the units of the conditional number of transistors and maximum signal path from the input to the output in the number of transistors, as well as using the Weibull distribution to estimate the probability of failure-free operation. Simulation of proposed hybrid redundancy in the system NI Multisim by National Instruments Electronics Workbench Group. The failure-free operation probability estimation in the computer mathematics system MathCad. Results. Expressions are obtained for the estimates of complexity, time delay and probability of failure-free operation of redundant digital circuits; curves are built in the Mathcad. Simulation confirms the performance of the proposed redundancy options. Conclusions. The conducted studies allowed us to establish the effectiveness of hybrid redundancy to improve the reliability and the radiation resistance of the digital circuits.

The earthquake impact on telecommunications infrastructure in Nepal: a preliminary spatial assessment

AbstractThis paper examines the spatial clustering and correlation of epicentres of the 2015 Gorkha earthquake and its spatial relationship to the telecommunications infrastructure of Nepal. Ripley's K function analysis suggests that epicentres of the main earthquake shock and aftershocks and base stations of worldwide Interoperability for microwave access are generally clustered. However, the cluster patterns decline over distance. Moran's I statistics further suggested that the epicentres and base stations at the district level are spatially significant and positively correlated. As Nepal is one of the most earthquake‐prone countries in the world, this paper recommends that the Government of Nepal, operators, and other concerned parties should identify the importance of telecommunications infrastructure and develop a critical infrastructure plan including location and redundancy options to mitigate and minimize the detrimental impacts of earthquakes and other disasters on telecommunications services in the country.

The Earthquake Impact on Telecommunications Infrastructure in Nepal: A Preliminary Spatial Assessment

This paper examines the spatial clustering and correlation of epicenters of the 2015 Gorkha earthquake and its spatial relationship to the telecommunications infrastructure of Nepal. Ripley’s K function analysis suggests that epicenters of the main earthquake shock and aftershocks and base stations of Worldwide Interoperability for Microwave Access are generally clustered. However, the cluster patterns decline over distance. Moran’s I statistics further suggested that the epicenters and base stations at the district level are spatially significant and positively correlated. As Nepal is one of the most earthquake-prone countries in the world, this paper recommends that the Government of Nepal, operators, and other concerned parties should identify the importance of telecommunications infrastructure and develop a critical infrastructure plan including location and redundancy options to mitigate and minimize the detrimental impacts of earthquakes and other disasters on telecommunications services in the country.

Evaluation of Redundancy for Power Generating Unit in a Cogeneration Power Plant

Redundancy system is very useful to enhance the performance and reliability of the power generation system of a cogeneration plant. However, the associated operating cost of redundancy system is very high. The common redundancies used in a cogeneration power plant are public utility and generator set. In order to select the best redundancy options which incurs minimum operating cost, it is required to evaluate the cost of different redundancy options. In this paper, net present value model (NPV) is developed to evaluate the cost of redundancy considering availability and reliability of the cogeneration system. Two steps applied to evaluate the redundancy cost of the cogeneration system. The first step is predicting the number of failures and downtime hours using availability and reliability analysis because redundancy is frequently used when the system failed. The second step is evaluating the cost of redundancy using NPV model. The results indicate that the use of public utility as redundancy option is costly compared to generator set option for long period of time. The major operation cost of public utility is contributed by the maximum demand charge cost which is about 57.9% of the total cost of redundancy. The study will be useful as a guide for the cogeneration operation to evaluate and select the redundancy option.

On the Non-Existence of Redundant Options

In a seminal paper, Ross (Q J Econ 90:75–89, 1976) shows that if security markets are resolving, then there exist (non-redundant) options that generate complete security markets. Complementing his work, Aliprantis and Tourky (2002) show that if security markets are strongly resolving and the number of primitive securities is less than half the number of states, then every option is non-redundant. Our paper extends Aliprantis and Tourky’s result to the case when their condition on the number of primitive securities is not imposed. Specifically, we show that if there exists no binary payoff vector in the asset span, then for each portfolio there exists a set of exercise prices of full measure such that any option on the portfolio with an exercise price in this set is non-redundant. Since the condition that there exists no binary payoff vector in the asset span holds generically, redundant options are thus rare.

A Power Conversion Concept for the Jupiter Icy Moons Orbiter

The Jupiter Icy Moons Orbiter (JIMO) mission is currently under study by the Office of Space Science under the Project Prometheus Program. JIMO is examining the use of Nuclear Electric Propulsion (NEP) to carry scientific payloads to three Jovian moons. A potential power system concept includes dual 100 kWe Brayton converters, a deployable pumped loop heat rejection subsystem, and a 400 Vac Power Management and Distribution (PMAD) bus. Many trades were performed in aniving at this candidate power system concept. System-level studies examined design and off-design operating modes, determined startup requirements, evaluated subsystem redundancy options, and quantified the mass and radiator area of reactor power systems from 20 to 200 kWe. In the Brayton converter subsystem, studies were performed to investigate converter packaging options, and assess the induced torque effects on spacecraft dynamics due to rotating machinery. In the heat rejection subsystem, design trades were conducted on heat transport approaches, material and fluid options, and deployed radiator geometries. In the PMAD subsystem, the overall electrical architecture was defined and trade studies examined distribution approaches, voltage levels, and cabling options.

Designing fault-tolerant distributed archives for picture archiving and communication systems.

Distributed archives in a picture archiving and communication system (PACS) environment can provide added fault tolerance and fail-over capability, as well as increased load capacity at a more economical price than traditional 'high-availability" systems. Systems can be configured with varying levels of fault tolerance, depending on the amount of redundancy desired. There is, however, a direct correlation between the level of hardware redundancy and cost to implement. This presentation details the system design for fault-tolerant distributed archives as well as several options for redundancy, referencing implementation of a fault-tolerant archive system at the University of Utah. The distributed archive system described here is based on Image Devices' image archive software, which can be implemented on multiple individual archive servers in order to distribute archive functionality and operational load. The configuration and implementation of the individual servers together make up the distributed archive system and does not impact the ability of the system to be scaled to meet future requirements. Several implementation and configuration options exist, including the ability for servers to maintain replicated databases containing patient and image information. Thus, each archive can be aware of all information and the location of this information within the distributed archive system. The goal is to produce systems that will still be operational in the event of any single point of failure, ie, a network connection failure between facilities or the failure of a single archive server within the distributed system. During normal operation, workload for image acquisition, image routing and image query requests will be distributed between the archive servers. If the system is deployed in a multifacility environment, each archive server can be configured to be responsible for the acquisition and image distribution management within that server's local facility. If the system is deployed in a single facility environment, load can be distributed evenly between the archive servers based on an understanding of the workload requirements generated be each acquisition and display device in the system. In the event that an archive server fails, other archive servers within the system will have the ability to provide some or all of the failed server's functionality. The degree of fail-over capability is dependent on the archive server's configuration as well as hardware redundancy employed. Three levels of fault-tolerant design can be achieved with this system architecture: (1) duplicate work capability only; (2) duplicate work capability and short-term image cache; (3) duplicate work capability, short-term image cache, and longterm image archival. Using the basic fault-tolerant design above, we have implemented a multifacility distributed archive system at the University of Utah. This system was implemented at a fraction of the cost of true "high-availability" archive architectures yet provides constant up time for the PACS system. If the network connection between the two locations goes down, each site is still fully functional for soft-copy read, as well as image acquisition and distribution. If either of the archive servers goes down, the image sources are redirected to the other archive server. The operational server then handles image distribution for both locations. Access to images in the short-term image cache is available to both archive servers and is not affected by loss of the network connection or remote server. Because there is ony one long-term archive device, the ability to retrieve images from long-term storage is the only function compromised by a network or server failure. By implementing distributed archives in a PACS environment, it is possible to achieve a highly fault-tolerant system without the expense of high-availability hardware and software. The design concepts outlined here can be applied to any PACS system that supports distributed archive functionality.

Redundancy strategies for a high splitting optically amplified passive optical network

High splitting, optically amplified, passive optical networks (SuperPONs) are investigated in terms of redundancy provision and protection mechanisms. Options for redundancy, including the important special case of dual homing, are detailed, and it is determined as to which of these options (duplication of the feeder and first distribution section, and N+1 protection of the optical amplifiers in the amplified splitter) would be required to be provided to all attached users to facilitate appropriate availability of the basic telephony service. The distributed amplified splitter dual homing solution is found to outperform the single amplified splitter solution in terms of its survivability. The protection mechanisms necessary to automatically switch to the redundant provision are discussed and it is seen that with the aid of suitable regular precautionary procedures protection switching can generally be provided rapidly (<50 ms). Finally, an availability, and cost versus availability, study confirms the aforementioned redundancy assessment for fiber-to-the-home (FTTH) implementations, but shows fiber-to-the-curb (FTTC) as needing additional redundancy.

Maintenance Float Policy: A Critical Component of Capacity Strategy

Several options exist for operations managers to control maintenance intensity. The effects of the maintenance department capability and the redundancy options within the context of capacity strategy are examined. In viewing the operations manager as a monitoring specialist, the firm′s choice is shown to depend on the economic, social, and technological implications inherent in the design of maintenance float policy.