High System Reliability Research Articles

A Low Cost, High-Reliability Receiver System for Reading Passive RFID Tags

Radio-Frequency Identification (RFID) is one of the leading enabling technologies of the Internet of Things (IoT) at low cost and high granularity scenarios. The cost of implementing IoT applications concerns the development and operation of receiver systems for reading labels. In this paper, we propose a low-cost receiver system based on off-the-shelf components allied to the development of a microstrip antenna. The proposed system is capable of receiving and processing digital signals scattered back from a passive RFID tag. The proposal relies on a Python application embedded in Raspberry Pi hardware, in which a bank of digital filters processes the signal. The proposal separates the received signal into sub-bands and implements a decision-maker that detects and codes radiofrequency carriers’ presence in sub-bands. Simulation using artificial random noise proves that the proposed and implemented decision-maker achieves 92% reliability for a Signal-to-Noise ratio between 1.6 dB and 2.3 dB. The evaluation of the printed dipole antennas pair for the RFID receiver system indicates a return loss of 19.22 dB for operation at 915 MHz.

A survey on cooperative control strategies for DC microgrids

Distributed generators have been widely used in modern power systems, and microgrids are becoming a key concept for the integration of multiple distributed generators and clusters of loads with great efficiency and high system reliability. In a microgrid, the control strategy is one of the most important issues. Various control schemes have been proposed to achieve the cooperation of distributed generators in a microgrid. This paper surveys cooperative control strategies for multiple distributed generators in DC microgrids. The three popular coordinated control strategies are presented: decentralized control, centralized control, and distributed control. The advantages and drawbacks of the control strategies are compared. Some intelligent control methods such as fuzzy logic control and neural network approaches are also briefly introduced in the context of microgrids. Further research trends and challenges in this area are also discussed.

Design and Fabrication of Chainless Bicycle

Abstract: Today's life we meet number of difficulties in transportation. There are number of drives to transmit the power. We have concentrated on bicycle where the efforts while peddling is not efficiently turned to work. In bicycle chain drive is used. Due to the chain drive there is loss of power in transmission. So our idea is to replace chain drive by kinematic links for higher transmission. This project is developed for the users to rotate the back wheel of a bicycle using kinematic links. Power transmission through chain drive is the oldest and widest used method in case of bicycle. In this paper we implemented the chain less transmission to the bicycle to overcome the various disadvantages of chain drive. Recently, due to advancements in kinematic link technology, a small number of modern link-driven bicycles have been introduced. Usually in bicycle, chain and sprocket method is used to drive the back wheel. The link drive only needs in small amount of lubrication using a grease to keep the links running quiet and smooth. A link drive bicycle is a bicycle that uses a link drive instead of a chain which contain four set of link at both the ends to make a new kind of transmission system for bicycle for getting high reliability system, and more safe system. Link-driven bicycle have used four bar mechanism where a conventional bicycle connected in one end pedal link and another connected in wheel. This pedal link actuate to drive a wheel. The use pedals to be actuate in 45 degrees wheels can rotating at 180 degrees. According to the direction of motion of pedal, the wheel will be moved forward. This avoids the usage of chain and sprocket method. This “chinless” drive system provides smooth quite and efficient transfer of energy from the pedals to the rear wheel. It is attractive in look compare with chain driven bicycle. Keywords: Chainless bicycle, four bar mechanism, kinematic link technology.

Is this as good as it gets? Implications of an asymptotic mortality decline and approaching the nadir in pediatric intensive care.

Despite advances in medicine, some children will always die; a decline in pediatric intensive care unit (PICU) mortality to zero will never be achieved. The mortality decline is correspondingly asymptotic, yet we remain preoccupied with mortality outcomes. Are we at the nadir, and are we, thus, as good as we can get? And what should we focus to benchmark our units, if not mortality? In the face of changing case-mix and rising complexity, dramatic reductions in PICU mortality have been observed globally. At the same time, survivors have increasing disability, and deaths are often characterized by intensive life-sustaining therapies preceded by prolonged admissions, emphasizing the need to consider alternate outcome measures to evaluate our successes and failures. What are the costs and implications of reaching this nadir in mortality outcomes? We highlight the failings of our fixation with survival and an imperative to consider alternative outcomes in our PICUs, including the costs for both patients that survive and die, their families, healthcare providers, and society including perspectives in low resource settings. We describe the implications for benchmarking, research, and training the next generation of providers.Conlusion: Although survival remains a highly relevant metric, as PICUs continue to strive for clinical excellence, pushing boundariesin research and innovation, with endeavors in safety, quality, and high-reliability systems, we must prioritize outcomes beyond mortality, evaluate "costs" beyond economics, and find novel ways to improve the care we provide to all of our pediatric patients and their families. What is Known: • The fall in PICU mortality is asymptotic, and a decline to zero is not achievable. Approaching the nadir, we challenge readers to consider implications of focusing on medical and technological advances with survival as the sole outcome of interest. What is New: • Our fixation with survival has costs for patients, families, staff, and society. In the changing PICU landscape, we advocate to pivot towards alternate outcome metrics. • By considering the implications for benchmarking, research, and training, we may better care for patients and families, educate trainees, and expand what it means to succeed in the PICU.

Research Group Introduction: Inamori Laboratory, Dept. of Electrical and Electronic Engineering, Tokai University

Our research focuses on the high efficiency wireless power transmission and reliable wireless communication system. The activities thorough women in engineering in IEEJ are also introduced.

Reliability optimization of linear consecutive-k-out-of-n: F systems driven by reconfigurable importance

As a typical kind of reconfigurable system, linear consecutive-k-out-of-n: F (Lin/Con/k/n: F) systems have a wide application in some complex engineering systems, such as oil pipeline systems, spacecraft relay station systems, and batch sampling-based quality control systems. Considering the high-reliability requirements for complex systems, how to improve the system reliability cost-effectively is critical to economically grantee the high reliability and long lifetime of practical systems. The reconfigurable features of Lin/Con/k/n: F systems provide a feasible integrated method, combining component rearrangement and component maintenance, to maximize the system's reliability after a period of operation. Moreover, the reconfigurable importance (RI) can evaluate the contribution of a component to improve the system reliability, and RI also can assess the relationship between component reliability and the optimal arrangement. Thus, a reconfigurable importance-based genetic algorithm (RIGA) is proposed to solve the reliability optimization problem of Lin/Con/k/n: F systems by utilizing the advantages of RI and GA. Experiment 1 (for typical systems) and Experiment 2 (for different types of components) are designed to illustrate the cost-effective characteristics of RIGA. In addition, a numerical example of production monitoring systems (PMS) further demonstrates the effectiveness of RI for guiding the solving process of the reliability optimization problem.

5G-based earthwork monitoring system for an unmanned bulldozer

Unmanned construction machineries have been developed to meet the precise construction design requirements and improve productivity. As indispensable equipment for the earthwork process, bulldozers with unmanned design and automatic operation are of considerable importance. This paper presents an unmanned bulldozer for automatic construction, and the earthwork monitoring system is realized on the basis of 5G. The perception and communication systems are deployed on the basis of the design of unmanned bulldozers without a cab. The mechanical parameters of the unmanned bulldozer are collected through CAN by Tbox and communicated with the digital cloud platform through 5G. Furthermore, the Tbox receives the construction instructions from the digital cloud platform and sends them to the mechanical actuator of the unmanned bulldozer via CAN. Finally, the test verifies the high reliability and ultra-low latency of the earthwork monitoring system based on 5G for the unmanned bulldozer.

Operation Characteristics of Mechanical DC Circuit Breaker Combined with LC Divergence Oscillation Circuit for High Reliability of LVDC System

DC systems are modernly starting to come into the spotlight again due to the carbon-neutral policy, the development of semiconductor devices for power, and the increase in digital loads. We need to prepare in advance solutions to problems that may arise from fault currents due to transients for future DC power grid models. In the case of DC, there is no current zero-point because there is no frequency. Therefore, a large switching surge is generated when the circuit breaker cuts off the fault current. The possibility of insulation breakdown is greater than that of AC in severe cases. We consider power semiconductors or superconducting current limiters as an alternative. However, DC breaking cannot be safely achieved by itself. For reliable DC breaking, mechanical circuit breakers must be used with them. Among the mechanical shut-off methods, we adopted the divergence oscillation method. It has the biggest advantage compared to other methods in that it has a simple structure by composing passive elements and can artificially create zero current. In addition, it can be applied to a power semiconductor and a superconducting current limiter to perform a high-reliability cut-off operation. In this paper, we conducted simulation analysis by configuring the DC power grid and DC cut-off system through the PSCAD/EMTDC program. Results confirmed that the application of the LC divergence oscillation circuit can reduce the cut-off time and reduce the power burden of the mechanical DC circuit breaker (MCB).

Compact and high reliable frequency-stabilized laser system at 589 nm based on the distributed-feedback laser diodes

Compact and high reliable frequency-stabilized laser system at 589 nm based on the distributed-feedback laser diodes

Optimal sizing and energy scheduling of grid-supplemented solar PV systems with battery storage: Sensitivity of reliability and financial constraints

Establishing reliable, clean, and inexpensive solar PV systems is a complex interplay between the level of reliability (LPSP), financial constraints, and CO2 emissions. This paper investigates the impact of these factors on stand-alone (SA) and grid-supplemented (GS) solar PV systems over multiple seasons. The research uses established hardware models, detailed power management strategies as well as realistic Australian grid tariffs and Genetic Algorithms to find the minimum Cost of Energy (COE) subject to LPSP and financial constraints. The developed power management strategies are also tested experimentally on a real solar PV system. The results indicate that the grid-supplemented system yields 30% lower COE compared to the stand-alone at baseline (LPSP<0.01) but achieves this at the expense of 17% higher life cycle emissions (LCE, kgCO2-eq/kWh). The results also revealed that in the grid-supplemented systems, only optimum renewable to grid penetration ratios can yield minimum COE which were found to be 95% and 5% respectively in this case study. A typical increase in the COE with tighter LPSP is found for the stand-alone systems. Whilst in the grid-supplemented systems, higher system's reliability can be achieved at almost the same COE but with increased emissions. In terms of tariff structures, the time of use tariff structure offers a marginally lower COE (0.30$/kWh) compared to the anytime flat tariff (COE = 0.32$/kWh), but with the latter outperforming in terms of LCE. The analyses presented help identifying the parameters to be considered in establishing more cost-effective solar PV systems.

Primary Research of a New Zero-Liquid-Discharge Technology of Wet Flue Gas Desulfurization Wastewater by Low-Rank Heat from Flue Gas

Wet flue gas desulfurization (WFGD) wastewater treatment is a key problem in coal-fired plants. Traditional chemical precipitation methods cannot reach zero-liquid discharge (ZLD). In this paper, a new technology using the low-rank heat from flue gas to concentrate the wastewater for ZLD is proposed. A scrubber was built to verify the concentrating process, and the characteristics of the concentrated water were analyzed. The concentrated water was neutralized by adding Ca(OH)2 to raise the pH value. The wastewater can be concentrated 10~25 times to reduce the flow rate. The characteristics of the concentrated wastewater were studied by dosing lime. Then, liquid and solids were separated by filter pressing, the liquid was mainly composed of CaCl2, which accounts for 73.6%. The sludge is composed of CaSO4 and Mg(OH)2, depending on the lime consumption of the dosing process. Finally, the filter liquor after the filter press was mixed with ash to reach zero liquid discharge, and the sludge could be burnt after mixing with the coal or disposed by third-part vendor. This technology is demonstrated in one 600 MW unit and shows a high system reliability. The clean water is recycled by the WFGD wastewater during the evaporation. Binding on the environmental policies and large market demand of the WFGD wastewater, this technology shows a great application prospect in the future.

2019년 원전 인적행위 관련사례 경향분석

Events at nuclear power plants are very rare. It is not easy to find lessons with the existing methods of carrying out improvement activities based on lessons learned from the event. In addition, high reliability systems are quite vulnerable to human error. So human performance require periodic management. For the managing human performance, most nuclear power plants identify the weak points and seek to improve human performance. Also, they evaluate and give feedback on human performance levels through periodic monitoring. In this paper, the major causes and upper control limit were selected for trend analysis in human performance related events at nuclear power plants in 2019. In addition, additional analysis was conducted in subjects exceeding the upper control limit. So several insights were discovered and corrective actions will be conducted to improve human performance in nuclear power plant.

Review of electro-hydraulic hitch system control method of automated tractors

The automatic and intelligent degree of tractor hitch system determines the operations quality, efficiency, tractor power output and energy consumption, and automatic control of electro-hydraulic hitch is one of the key technical problems in the realization of automated tractor. In this study, the adjustment methods and characteristics of electro-hydraulic hitch system were summarized. The development of electro-hydraulic hitch control technologies was elaborated and analyzed from both the electro-hydraulic control strategy and slip control strategy perspectives. The implementation methods and control characteristics were discussed. A new idea for the development of automated tractor was put forward that integrating cutting-edge technologies such as big data, fusion control and artificial intelligence. In addition, based on the precise and efficient control of electro-hydraulic hitch system, a high reliability of the control system of the tractor with intelligent application of the control algorithm was obtained. The results can provide a reference for the precise operation of automated tractors under the big data in agriculture. Keywords: automated tractors, electro-hydraulic hitch, control algorithm, draft-position control, slip rate control DOI: 10.25165/j.ijabe.20211403.6175 Citation: Wang L, Wang Y, Dai D, Wang X, Wang S M. Review of electro-hydraulic hitch system control method of automated tractors. Int J Agric & Biol Eng, 2021; 14(3): 1–11.

Structure and substructure connectivity of divide-and-swap cube

High fault tolerance and reliability of multiprocessor systems, modeled by interconnection network, are of great significance to assess the flexibility and effectiveness of the systems. Connectivity is an important metric to evaluate the fault tolerance and reliability of interconnection networks. As classical connectivity is not suitable for such large scale systems, a novel and generalized connectivity, structure connectivity and substructure connectivity, has been proposed to measure the robustness of networks and has witnessed rich achievements. The divide-and-swap cube DSCn is an interesting variant of hypercube that has nice hierarchical properties. In this paper, we mainly investigate H-structure-connectivity, denoted by κ(DSCn;H), and H-substructure-connectivity, denoted by κs(DSCn;H), for H∈{K1,K1,1,K1,m(2≤m≤d+1),C4}, respectively. In detail, we show that κ(DSCn;K1)=κs(DSCn;K1)=d+1 for n≥2, κ(DSCn;K1,1)=κs(DSCn;K1,1)=d+1 for n≥8, κ(DSCn;K1,m)=κs(DSCn;K1,m)=⌊d2⌋+1 with 2≤m≤d+1 for n≥4, κ(DSCn;C4)=3+2(d−2) for 4≤n≤8, ⌊d2⌋+1≤κ(DSCn;C4)≤d+1 for n≥16 and κs(DSCn;C4)=⌊d2⌋+1 for n≥4. Finally, we compare and analyze the ratios of structure (resp. substructure) connectivity to vertex degree of divide-and-swap cube with that of several well-known variants of hypercube.

Application of Hierarchical Colored Petri Nets for Technological Facilities’ Maintenance Process Evaluation

The high reliability of modern engineering systems is achieved by performing predictive maintenance. Mathematical models based on stochastic timed colored Petri nets are an effective tool for developing complex production processes for Industry 4.0. This article discusses the maintainability evaluation used in hierarchical Petri net models. The hierarchical simulation model was built using timed colored Petri nets, and was constructed with four levels of repair and maintenance modules. New module structures are proposed for simulating the schedule of production tasks and interaction with technological units. The emphasis is on the processes of predicting maintenance and repair, moving units to service, replacing units, and forming a reserve. The design of the simulation modules allows the setting of probabilistic parameters for the distributions of equipment failures, requests for unit maintenance, repair time, and recovery time after repair. The article proposes to use the hierarchical Petri model in conjunction with solving the problem of minimizing the cost of service. The iterative procedure consists of obtaining an approximate unit distribution by tasks, subsequent simulation of the technological process, and adjusting the optimization problem constraints. For example, the hierarchical Petri net is considered to assess the maintainability of autonomous agricultural vehicles. The results of the simulation experiments are presented. A simulation of the agrotechnical production process was performed, during which vehicles were maneuvered, taken out for repair or maintenance, and returned to the reserve fund. The interdependencies of preventive maintenance periods, service operations, failure rates, and predictive maintenance requests were obtained in order to comply with the task scheduling. The proposed model is a generalization, but it is especially effective in studying mobile equipment servicing.

A New Dynamic Simulation Test Method of Intelligent Electricity Metering System

Electricity metering is the core supporting technology for realizing accurate perception of electricity consumption, reasonable dispatching of power grids, rapid market response, diversified charging and new forms of electricity marketing. However, due to the significant differences in the actual metering environment, the operation of the electricity metering and information collection system is unstable, showing many problems such as unsuccessful parameter delivery and low acquisition success rate, which severely restricts the development of smart grid two-way interactive technology and the realization of smart electricity consumption in the last mile. There is an urgent need for a reliable and accurate dynamic simulation and systematic testing method to realize the reproduction and testing of various field faults. In this paper, we propose a new type of dynamic simulation test method for intelligent electricity metering system, which can realize the performance test, fault dynamic simulation, location and recovery of each functional unit of the master station, collection terminal and smart meter. Through experimental testing, our dynamic simulation test methods can realize the rapid recurrence of on-site problems, improve the high reliability and normal operation of the electric energy metering information collection system.

Performance of digital servos in an optical frequency transfer network.

We demonstrate the use of three kinds of flexible digital servos for the stabilization of the optical fiber link, the interferometer temperature, and the polarization of the transmitted light at the remote site, respectively. The main fiber noise cancellation digital servo provides a large phase detection range (∼210π radians), automatic relock function, and low cycle-slip rate over a 62 km field-deployed fiber link achieved by utilizing a feedback optical actuator of an acousto-optic modulator fed by a voltage-controlled oscillator. The temperature control and polarization control digital servos enable that the temperature of the interferometer can be stabilized at a stability of 0.01K and the data uptime is enhanced from 85.5% to 99.9% by implementing the polarization controller. The results demonstrate that the performance of the three digital servos is sufficient for high-precision optical frequency transfer applications and indicates comparable performance to existing analog optical frequency control systems. The full digital controlled optical frequency transfer method demonstrated here provides guidance for the development of a low-cost, low-complexity, and high-reliability optical frequency transfer system.

Channel Modeling of an Optical Wireless Body Sensor Network for Walk Monitoring of Elderly.

The growing aging of the world population is leading to an aggravation of diseases, which affect the autonomy of the elderly. Wireless body sensor networks (WBSN) are part of the solutions studied for several years to monitor and prevent loss of autonomy. The use of optical wireless communications (OWC) is seen as an alternative to radio frequencies, relevant when electromagnetic interference and data security considerations are important. One of the main challenges in this context is optical channel modeling for efficiently designing high-reliability systems. We propose here a suitable optical WBSN channel model for tracking the elderly during a walk. We discuss the specificities related to the model of the body, to movements, and to the walking speed by comparing elderly and young models, taking into account the walk temporal evolution using the sliding windowing technique. We point out that, when considering a young body model, performance is either overestimated or underestimated, depending on which windowing parameter is fixed. It is, therefore, important to consider the body model of the elderly in the design of the system. To illustrate this result, we then evaluate the minimal power according to the maximal bandwidth for a given quality of service.

What Moves People Living With Dementia? Exploring Barriers and Motivators for Physical Activity Perceived by People Living With Dementia in Care Homes.

There is a lack of intervention promoting physical activity targeted toward people living with dementia because their input has not been prioritized in the development of exercise programs. The aim of this study is to investigate motivators and barriers concerning physical activity in people living with dementia in care homes and to give recommendations for intervention development. Qualitative semi-structured interviews were conducted; transcripts were analyzed using qualitative content analysis. Following a tailored procedural model, inductive and deductive category development was applied. The value of Cohen’s κ = .94 indicates the high intercoder reliability of the category system developed. Ten interviewees reported 24 different barriers and 12 motivators concerning physical activity in the context of the social-ecological model. The strong impact of intrapersonal factors and the living environment became apparent. Points of reference for how people living with dementia can overcome barriers and activate their motivators to achieve more physical activity are provided.

Effect of disclosing the relation between effort and unit reliability on system reliability: An economic experiment.

The purpose is to experimentally examine the effect of disclosing the risk probability of each unit in a production system on human behavior and the resulting system reliability. We used an economic experiment based on the theoretical model of Hausken (2002) to evaluate the effect of disclosing the relation between effort and unit reliability. We conducted first the non-disclosed-risk experiment and then the disclosed-risk experiment within subjects in both series and parallel systems. Our experimental results show that disclosing the relation between effort and unit reliability has two positive effects. First, subjects succeeded in improving the system reliability while cutting back on efforts to reduce the risk of their units when the risk probability was disclosed. In each system, the disclosed-risk condition achieves significantly higher system reliability on average than does the non-disclosed-risk condition, although the average level of effort is significantly lower under the disclosed-risk condition than under the non-disclosed-risk condition. Second, disclosing the risk probability simplified the subjects' decision-making process and reduced its cost because subjects made their decisions on the amount of effort to exert based only on the risk probability information without considering other factors, such as the number of accidents.