Combustion Fault Simulation of Diesel Engine Based on AVL-FIRE Software

Marine diesel engine is developing towards the direction of precision, automation and systematization, and it has the characteristics of complex structure and many parts. If it breaks down, it will affect the operation safety of the whole ship. If it is serious, accidents may occur, which may cause maritime accidents. Therefore, how to prevent the occurrence of marine diesel engine failure and analyze the cause of failure after the accident has been paid more and more attention by scholars at home and abroad. In the simulation study of the working process of diesel engine, for different types of diesel engines, the laws of combustion process are different, even for the same diesel engine in different working conditions, the combustion laws are also different, which will cause great difficulties to study the combustion process. Using computer simulation technology, the physical calculation model of diesel engine system is established by simulating the typical combustion faults of marine diesel engine. AVL-FIRE software is used to simulate different faults of diesel engine combustion process, and the changes of various performance parameters of diesel engine under corresponding faults are obtained, so as to grasp its working state macroscopically, and provide relevant basis for the design, optimization and operation management of diesel engine system.

Fault simulation in networks with isolated neutral to find the fault location in power transmission lines

The paper deals with an urgent problem - determining the location of damage to an overhead power transmission line. In particular, the application of the wavelet transform is considered, which makes it possible to localize the temporal position of the frequencies and to determine the time interval of the presence of the frequency in the event of damage to the power line. The paper presents a mathematical model that makes it possible to determine the amplitude-frequency spectrum, by which it is possible to determine the presence of a certain frequency in the signal under study, by which it is possible to determine the fault location. Based on the wavelet transform, the spectra of the current and voltage in the damaged phase in the isolated neutral mode are obtained. It is shown that when the neutral mode is switched, there are no dangerous overvoltage or current surges in the network, and the overvoltage level is reduced.

Response Analysis of a Scraper Conveyor under Chain Faults Based on MBD-DEM-FEM

To tackle the difficulty in obtaining the response data of chain and bulk coal under chain faults, this paper uses a new method for the fault simulation of scraper chains based on the coupling of multi-body dynamics (MBD), discrete element method (DEM), and finite element method (FEM). With the force and stacking angle as response values, the contact parameters of bulk coal were revised using a rotary transport test. The simplified DEM-MBD model was verified from the resistance using the point-by-point method. The static structure model of the chain was verified by the chain tensile experiment. The DEM-MBD coupling results show that when the chain is stuck or broken, the dynamic properties of the chain and bulk coal fluctuate sharply, and the wear of the medium plate increases. Based on the DEM-MBD coupling results and the DEM-FEM unidirectional coupling, the stress, strain and life were acquired, and were verified experimentally. Regarding the fracture, the Plackett-Burman test was used to determine that the crack depth, initial angle, and tensile load significantly affect the stress intensity factor (SIF). The quadratic model between significant factors and SIF was constructed using the response surface method, which provides a reference for the simulation of the scraper conveyor, the fault mechanism, and the optimization of the design of the chain.

Rolling Bearing Fault Diagnosis by Aperiodic Stochastic Resonance Under Variable Speed Conditions

The fault characteristic of rolling bearings under variable speed condition is a typical non-stationary stochastic signal. It is difficult to extract due to the interference of strong background noise makes the applicability of traditional noise reduction methods less. In this paper, an aperiodic stochastic resonance (ASR) method is proposed to study the fault diagnosis of rolling bearings under variable speed conditions. Based on numerical simulation, the effect of noise intensity and damping coefficient on the ASR of the second-order underdamped system is discussed, and an appropriate damping coefficient is found to reach the optimal ASR. The proposed method enhances the fault characteristic information of bearing fault simulation signal. Corresponding to rising-stationary and the stationary-declining running conditions, the method is verified by both simulated and experimental signals. It provides reference for fault diagnosis under variable speed condition.

VECTOR-DRIVEN LOGIC AND STRUCTURE FOR TESTING AND DEDUCTIVE FAULT SIMULATION

Context. It is known that data structures are decisive for the creation of efficient parallel algorithms and high-performance computing devices. Therefore, the development of mathematically perfect and technologically simple data structures takes about 80 percent of the design time, when about 20 percent of time and material resources are spent on algorithms and their hardware-software coding. This lead to search for such primitives of data structures that will significantly simplify the parallel high-performance algorithms which are working on them. Models and methods for testing and simulation of digital systems are proposed, which containing certain advantages of quantum computing in terms of implementation of vector qubit data structures in technology of classical computational processes. Objective. The goal of the work is development of an innovative technology for qubit-vector synthesis and deductive analysis of tests for their verification based on vector data structures that greatly simplify algorithms that can be embedded as BIST components in digital systems on chips. Method. The deductive faults simulation is used to obtain analytical expressions focused on transporting fault lists through a functional or logical element based on the xor-operation, which serves as a measure of similarity-difference between a test, a function and faults which is specified in the same way in one of the formats − a table, graph, equation. A binary vector is proposed as the most technologically advanced primitive of data structures for setting logical functionality for the purpose of parallel synthesis and analysis of digital systems. The parallelism of solving combinatorial problems is a physical property of quantum computing, which in classical computing, for parallel simulation and faults diagnostics, is provided by unitary-coded data structures due to excess memory. Results. 1) A method of analytical synthesis of deductive logic for functional elements on the gate level and register transfer level has been developed. 2) A deductive processor for faults simulation based on transporting input lists or faults vectors to external outputs of digital circuits was proposed. 3) The qubit-vector form of logic setting and methods of qubit synthesis of deductive equations for faults simulation were described. 4) A qubit-vector method for the tests’ synthesis which is using derivatives calculated by vector coverage of logic has been developed. 5) Models and methods verification is performed on test examples in the software implementation of structures and algorithms. Conclusions. The scientific novelty lies in the new paradigm of the technology for the synthesis of deductive RTL logic based on metric test equation, which forms the. A vector form for structures description is introduced, which makes it possible to apply wellknown technologies for the synthesis and analysis of logical circuits tests to effectively solve the problems of graph structures testing and state machine models of digital devices. The practical significance is reflected in the examples of analytical synthesis of deductive logic for functional elements on gate level and register transfer level. A deductive processor for faults simulation which is focused on implementation as a BIST tool, which is used in online testing, simulation and fault diagnosis for digital systems on chips is proposed. A qubit-vector form of the digital systems description is proposed, which surpasses the existing methods of computing devices development in terms of the metric: manufacturability, compactness, speed and quality. A software application has been developed that implements the main testing, simulation and diagnostics services which are used in the educational process to study the advantages of qubit-vector data structures and algorithms. The computational complexity of synthesis processes and deductive formulas for logic and their usage in fault simulation are given.

Embedded Radiation sensor with OBIST structure for applications in mixed signal systems

Oscillation based testing (OBT) has proven to be a simple and effective test strategy for numerous kind of circuits. In this work, OBT is applied to a radiation sensor to be used as a VLSI cell in embedded applications, implementing an oscillation built-in self-test (OBIST) structure. The oscillation condition is achieved by means of a minimally intrusive switched feedback loop and the response evaluation circuit can be included in a very simple way, minimizing the hardware overhead. The fault simulation indicates a fault coverage of 100% for the circuit under test.Keywords: fault simulation, mixed signal testing, OBIST, oscillation-based test, VLSI testing.

Short Circuit Analysis on Distribution Network 20 kV Using Etap Software

In an electric power system, electricity is generated by the power plant and then channeled to a transmission line and then distributed to consumers, in the process of distributing electrical energy, the system does not always work in normal conditions, sometimes the system can experience disturbances such as one-phase, two-phase, and three-phase disturbances. This interference can disrupt the electrical system and can damage equipment if left unchecked, therefore it is necessary to install a protection device that can decide the interference so as not to damage other equipment when a disturbance occurs. Here the protection device used is a circuit breaker. In a fault condition, the circuit breaker must be able to separate the points of the fault so as not to damage other electrical equipment. In this case, to determine the capacity of the best protection device for the system, a short circuit fault simulation is performed. To simplify the calculation process here the author uses the help of ETAP software (Electrical Transient Analysis Program).