Self-repair Method Research Articles

Multifunctional Cl-S double-doped carbon nitride nanotube unit in catalytic ozone oxidation synergistic photocatalytic system: Generation of ROS-rich region and effective treatment of organic wastewater

Catalytic ozone oxidation synergistic photocatalysis (COP) can effectively overcome the shortcomings of incomplete mineralization and strong pH dependence of O3 and slow reaction rate of photocatalytic. Cl, S double-doped carbon nitride nanotube unit (Cl/S-CN) with the ability of catalyzing O3 and visible light photocatalysis was synthesized by hydrothermal self-repairing method to improve the applicability of the COP system in actual organic wastewater. Characterization and density functional theory (DFT) calculations found that Cl/S-CN has a stable and ordered nanotube (tube diameter: 56 nm) arrangement, a good energy band structure, and excellent e- delivery efficiency. It can generate reactive oxygen species (ROS)-rich region in the unit to promote the ROS chain cycle reaction, thereby generating more numbers and types of (non–)free radicals to participate in the degradation of organic pollution. For tetracycline (100 mg/L), the degradation rate in O3/vis/Cl/S-CN system was 90.1% at 10 min, and the degradation rate of TOC was 78% at 30 min. For P-nitrophenol (20 mg/L), the degradation rate was 91.6% at 20 min, and the degradation rate of TOC was 66% at 30 min. The COD degradation rates of influent water, secondary effluent water and oilfield produced water in COP system at 30 min were 70.5%, 83.4% and 76.5%, respectively. Cl/S-CN can catalyze the production of high activity ROS-rich region in COP system, effectively promote the production of ·OH, 1O2 and other active substances, and improve the applicability of COP system in actual organic wastewater.

Embryonics Based Phased Array Antenna Structure With Self-Repair Ability

The reliability of phased array antenna can be improved with the self-repairing technology, and the existing self-repair method based on the TR module reconfiguration has problems such as slow calculation speed and difficulty in calculating the elements' mutual coupling, which is difficult to meet the application requirements. In this paper, a novel phased array antenna structure with self-repair ability is proposed. Based on the embryological electronics (embryonics), a novel phased array antenna structure with TR cell as the basic unit is constructed. The faulty TR cell can be detected and removed, and its influence on the phased array antenna's performance can be eliminated. The function and connection of faulty TR cell can be implemented by the normal TR cells and idle TR cells, the performance of phased array antenna can be repaired in real-time. TR cell, TR cell array and input/output switching control module are designed. The simulation tests show that, the phased array antenna with various fault conditions can be repaired in real-time based on the proposed structure, and the performance of phased array antenna can be repaired to the initial normal state with enough idle TR cells in array. Even without the idle TR cell, the performance of phased array antenna with fault can be improved through the self-repair. A new way for the design of phased array antenna design with self-repair ability is provided.

Tool electrode wear compensation in block divided EDM process for improving accuracy of diffuser shaped film cooling holes

Diffuser shaped film cooling holes are increasingly being applied in the turbine blades of advanced aeroengines. It is a difficult problem to machine this kind of cooling holes due to their complicated shape and superalloy material. Currently, die-sinking electrical discharge machining (EDM) is regarded as an available process for machining the diffuser holes. However, the change of tool electrode shape caused by the electrode wear and difficult renew of dielectric fluid affect the processing precision. The worn tool electrode has to be replaced with a fresh one after machining one or several holes. The replacing procedure is time consuming to break the machining process. In the previous work, a novel block divided EDM process was proposed to efficiently machine the diffuser holes, but the machining accuracy needs to be further improved. In this research, the block divided EDM process firstly is analyzed and simulated in detail to know the key factor affecting the machined accuracy. Furthermore, a self-repair method and a profile error compensation method of the tool electrode wear are proposed for improving the processing accuracy. The self-repair method is to plan and control the rotation motion of the tool electrode for maintaining its shape. The profile error compensation method is to modify the Z coordinate of the tool electrode for decreasing the machining error. Machining experiments verified that the proposed methods can meet the accuracy requirements of the film cooling holes with diffusion angle error < 0.1° and average profile error < 10 μm.

A Self-Repairing Digital System with High-Quality Scalability and Fault Coverage

In any fault tolerant or BIST system the primary goal is to covenant with faults that arise in the indented system. The proposed system using genetic algorithm to optimize the performance and area of given circuit. This approach is supple for combinational circuit design. The use of four spare cells simplifies the operation of the active block in the current system; it needs more space to establish itself so it is considered as overhead. The proposed method of fault detection and correction for logical errors using genetic algorithm decreases the area overhead. Detection of Fault in the memory unit through BIST implementation increases the speed but replacing the existing faulty block with fault free block degrades the fault analyzing capabilities. Utmost care has on all the works implemented for the process of minimizing the error in different digital process. Therefore, with the new scope of proposing the method of reducing the error flow for the application of medical field, aeronautical, satellite broadcasting is described very efficiently in this paper. The simulation results of the fault tolerant and self-repairing method using genetic algorithm is presented.

A decentralized sensor fault detection and self-repair method for HVAC systems

This study proposes a novel decentralized sensor fault detection and self-repair method for heating, ventilation and air-conditioning systems. From the perspective of network structure, sensor fault diagnosis in heating, ventilation and air-conditioning systems is distributed to the updated smart sensors without the monitoring host, which is necessary in the traditional centralized method. A fully distributed flat sensor network is established based on fundamental physical equations. Similar to the structure, mechanism and characteristics of biological communities, a smart sensor needs only to communicate with adjacent nodes and operate collaboratively to complete sensor fault detection and self-repair tasks. These tasks are formulated as a constrained optimization and are solved by a decentralized algorithm with a penalty function executed in all the sensor nodes in parallel. The diagnosis model introduces an exponential function method to determine the precise location and undertake self-repair of a fault node. Simulation results on a chilled water system illustrate the effectiveness of the proposed method. Practical application: The traditional sensor fault detection and diagnosis methods for heating, ventilation and air-conditioning systems are based on a centralized structure with several deficiencies, such as high maintenance and labor costs, link congestion and operational lag. This study presents a decentralized sensor network structure and exponential-function-based method that possess the advantages of plug-and-play, rapid deployment, high flexibility and convenience for engineering implementation without having to build a central monitor. The efficiency and effectiveness of the proposed method are demonstrated via a case study.

An Error-Detection and Self-Repairing Method for Dynamically and Partially Reconfigurable Systems

Reconfigurable systems are gaining an increasing interest in the domain of safety-critical applications, for example in the space and avionic domains. In fact, the capability of reconfiguring the system during run-time execution and the high computational power of modern Field Programmable Gate Arrays (FPGAs) make these devices suitable for intensive data processing tasks. Moreover, such systems must also guarantee the abilities of self-awareness, self-diagnosis and self-repair in order to cope with errors due to the harsh conditions typically existing in some environments. In this paper we propose a self-repairing method for partially and dynamically reconfigurable systems applied at a fine-grain granularity level. Our method is able to detect correct and recover errors using the run-time capabilities offered by modern SRAM-based FPGAs. Fault injection campaigns have been executed on a dynamically reconfigurable system embedding a number of benchmark circuits. Experimental results demonstrate that our method achieves full detection of single and multiple errors, while significantly improving the system availability with respect to traditional error detection and correction methods.

Evolution of Fault Self-Repairing Circuit with High Reliability

With the continuous improvement of the complexity of the microelectronic system, its reliability risk is becoming more and more obvious. In order to improve the reliability of electronic systems in complex electromagnetic environment, this paper proposes a new fault self-repairing method; the idea is to realize controllable silicon evolution on the FPGA. A MicroBlaze CPU and VRC array are designed, and the CPU runs the evolutionary algorithm to configure the VRC array, dynamically changing the structure and function of the circuit, so as to obtain high reliability of the digital fault self-repairing circuit. Evolving fault self-repairing technology provides a new way for the high reliability of the digital system design.

Board-level built-in self-repair method of RAM

This paper describes the method of built-in self-repairing of RAM on board, designs hardware circuit, and logic for the RAM’s faults self-repairing system based on FPGA. The key technology is that it utilizes FPGA to test RAM according to some algorithm to find out failure memory units and replace the faulty units with FPGA. Then it can build a memory that has no fault concern to external controller, and realizes the logic binding between external controller and RAM. Micro Controller Unit (MCU) can operate external RAM correctly even if RAM has some fault address units. Conventional MCS-51 is used to simulate the operation of MCU operating external memory. Simulation shows FPGA can complete the faulty address units’ mapping and MCU can normally read and write external RAM. This design realizes the RAM’s built-in self-repairing on board.

High-efficiency memory BISR with two serial RA stages using spare memories

As technology has become more advanced, the density of memory has increased greatly. This development has led to need for a high-efficiency redundancy analysis (RA) algorithm to improve yield rate. Presented is a new methodology that can achieve high-efficiency repair against faults in memory. Experimental results show that the proposed built-in self-repair (BISR) method performs well.

自律分散機械による3次元形状の自己組み立てと自己修復

A distributed self-assembly and self-repair method is proposed for a 3-D reconfigurable machine, composed of many identical mechanical units. The method aims to enable the machine to transform itself into desired structure from an arbitrary initial configuration. The proposed method is implemented in such a way that each unit has identical software, so that any unit can play any role in the system. The method consists of two parts, for small and large scale systems. The first part is featured by a stochastic relaxation process, which allows the system to converge to a given target structure by searching for a proper unit motion over many degrees of freedom. We have also developed another self-assembly and self-repair method dedicated to effective self-assembly and self-repair for large scale systems by using layered and recursive description of target shape. The effectiveness of the proposed method is verified through a series of computer simulations.

Self-assembly and self-repair method for a distributed mechanical system

We propose a self-assembly and self-repair method for a homogeneous distributed mechanical system. We focus on a category of distributed systems composed of numbers of identical units which can dynamically change connections among themselves. Each unit has an onboard microprocessor, and local communication between neighboring units is possible. We discuss a distributed method for a group of such units to metamorphose from an arbitrary configuration into a desired configuration through cooperation by the units. This process, called self-assembly, is realized by identical software on each unit with local inter-unit communication. An extension of self-assembly, self-repair, is also examined. In this process, an occasional cut-off of an arbitrary part of the system is assumed. When some part of the system detects damage, the whole system degenerates and reconstructs itself. Computer simulations show the feasibility of self-assembly and self-repair.