Double Faults Research Articles

Geological and Geophysical Studies of the Double Transform Fault Charlie Gibbs (North Atlantic) during Cruise 50 of R/V Akademik Nikolaj Strakhov

Geological and Geophysical Studies of the Double Transform Fault Charlie Gibbs (North Atlantic) during Cruise 50 of R/V Akademik Nikolaj Strakhov

Simultaneous actuator and sensor fault reconstruction of singular delayed linear parameter varying systems in the presence of unknown time varying delays and inexact parameters

SummaryIn this article, robust fault diagnosis of a class of singular delayed linear parameter varying systems is considered. The considered system has delayed dynamics with unknown time varying delays and also it is affected by noise, disturbance and faults in both actuators and sensors. Moreover, in addition to the aforementioned unknown inputs and uncertainty, another source of uncertainty related to inexact measures of the scheduling parameters is present in the system. Making use of the descriptor system approach, sensor faults in the system are added as additional states into the original state vector to obtain an augmented system. Then, by designing a suitable proportional double integral unknown input observer (PDIUIO), the states, actuator, and sensor faults are estimated. The uncertainty due to the mismatch between the inexact parameters that schedule the observer and the real parameters that schedule the original system is formulated with an uncertain system approach. In the PDIUIO, the uncertainty induced by unknown inputs (disturbance, noise and actuator, and sensor faults), unknown delays, and inexact parameter measures are attenuated in H∞ sense with different weights. The constraints regarding the existence and the robust stability of the designed PDIUIO are formulated using linear matrix inequalities. The efficiency of the proposed method is verified using an application example based on an electrical circuit.

Influence of scaling on match play characteristics in youth tennis: A systematic review

Scaled tennis is the downsized version of adult tennis and aims to allow youth players to play a type of tennis that resembles adult tennis. However, since the different scaling conditions (red, orange, lime and green tennis court) were chosen pragmatically it is unclear whether the match play characteristics of scaled tennis resemble those of adult tennis. It is also unclear whether the match play characteristics are comparable between the different scaling conditions (allowing a smooth transition through the scaled courts). Therefore, this systematic review aims to compare match play characteristics in scaled tennis to adult tennis, and to compare match play characteristics across the different scaling conditions. The PubMed, Web of Science and SPORTDiscus (EBSCO) databases were searched until November 2021. The match play characteristics included first serve percentage, percentage of first serve points won, percentage of second serve points won, percentage of total serve points won, number of aces, number of double faults, winners’ percentage, unforced errors percentage, percentage of break points won, rally duration and inter contact time. The systematic search identified 887 records and six studies were included. All included match play characteristics, apart from the percentage of second serve points won and a number of double faults, showed significant differences between scaled tennis and adult tennis. Similarly, all included match play characteristics, except for a number of double faults, showed significant differences between the different scaling conditions. Based on these results, future research is needed to optimise the different scaling conditions in terms of match play characteristics.

Analysis of Passive Islanding Detection Techniques for Double Line Fault in Three Phase Microgrid System

Microgrids are able to dispatch power to distribution systems with the advancement of power electronics-based inverters. As per IEEE-1547-2018 standards, Microgrid has to maintain voltage of 0.88 < V < 1.1 p.u (per unit) and frequency of 58.8< f_0 < 61.2 Hz and detect un-intentional faults in less than 2 seconds to bring Microgrid into islanding mode seamlessly. Unless these faults are detected and Microgrid is islanded, the system stability cannot be maintained and Microgrid cannot feed the connected loads. To detect these unsymmetrical faults, to bring the Microgrid to islanding mode and to be stable during non-islanding cases like loads switch on and throw off at Point of Common Coupling (PCC), a passive islanding detection method, Rate Of Change Of Voltage Phase Angle (ROCOVPA) is proposed. The methodology is simple. First, the voltage phase angle of generator bus and the grid is monitored. Then, absolute value is found and finally differentiated to get ROCOVPA and detect islanding. Also, this technique is compared with the widely used method of Rate Of Change Of Frequency (ROCOF) at different percentage active and reactive power mismatches. It also avoids nuisance tripping so that Microgrid's stability is maintained. This method is tested for un-symmetrical double line fault, for islanding cases and switch on or throw off, for non-islanding cases with linear and non-linear loads. In this method, the power quality is also not affected because of no perturbations during testing and the Non-Detection Zone (NDZ) is almost zero. The proposed method is verified by simulating islanding and non-islanding conditions in MATLAB/Simulink and by comparing with ROCOF method and found effective.

Combined ground-fault relay protection in 6–10 kV power grids

In the present work, engineering decisions for combined ground-fault relay protection in 6–10 kV power grids are addressed. For objects in electrical grids having a voltage of 6–10 kV, simple relay protection was used: overcurrent protection and current cutoff. The most common algorithms for single phase-to-earth fault relay protection were analysed and compared. The modelling allowed a scheme for automatic transfer switch to be designed. Operation algorithms of relay protection and automatics were established, considering the properties of an electrical grids section and the characteristics of possible operating conditions. In 6–10 kV electrical grids, an increase in the damage rate of cable lines with outdated thinned insulation was revealed. It was determined that long-term grid operation under a single phase-to-earth fault should be avoided since double earth faults may occur due to an increase in the voltage of healthy phases relative to earth by √3 times. The calculations performed to evaluate selectivity and sensitivity of the current protection of selective zero-sequence showed limited application (due to the insufficient sensitivity) of such protection from single phase-to-earth fault in some cases. The advantages of circuit designs, which use electromagnetic and inductive relays as protection fault detectors, and advanced compact elements in the form of microcircuits with electronic interconnection as logical elements, were investigated. It is established that the proposed solutions can be used by energy providers to increase the reliability and fail-safety of 6–10 kV distribution networks with the minimum capital expenditures to relaying systems. The presented analysis of systems and devices for phase-to-earth fault relay protection showed that power grids having isolated neutrals are the most problematic in terms of maintenance. Simplified circuit designs for combined protection circuits can be used for facilitating the maintenance of relaying devices and automatics due to their openness.

Single-Phase Voltage Source Multi-Level Inverter Hysteresis SVPWM Reconfigurable Fault-Tolerant Control Method

A hysteresis space vector pulse width modulation (SVPWM) reconfigurable fault-tolerant method for single-phase voltage source multi-level inverter with current tracking is proposed. Firstly, the influence of single switch open circuit fault and double switches open circuit fault on the voltage vector of the inverter is analyzed, and on this basis, the equivalent replacement of the voltage vector is obtained by using the topology reconstruction of the inverter, and the redundant voltage vectors with overlapping positions are preferred for equivalent replacement. If there are no coincident non-fault vectors, the other non-fault vectors with the closest position and effect are selected. The fault-tolerant method does not need the switching operation between the main power switching device and spare power switching device of the inverter, and can directly control the on–off process of the inverter reconfiguration unit through the driving signal of insulated gate bipolar translator (IGBT), which is simple and stable. Under the conditions of single switch open circuit and most double switches open circuit, the output current of the inverter can accurately track the reference current.

Modeling and Simulation of Mho Type Distance Relay for High Voltage Transmission Line Protection

Abstract-This paper describes the opportunity of implementing a model of a Mho type distance relay with three zones by using MATLAB/SIMULINK package. SimPowerSystem toolbox was used for detailed modeling of distance relay, transmission line and fault simulation. The proposed model was verified under different tests, such as fault detection which includes single line to ground (SLG) fault, double line fault (LL), double line to ground fault (LLG) and three phase fault, all types of faults were applied at different locations to test this model. The results show that the relay operates correctly under different locations for each fault type. Keywords- Distance relay, Single line to ground fault (L-G), Double line to ground (L-L-G), Line to Line fault (L-L), Three phase fault (L-L-L), MATLAB/SIMULINK.

A Reduced Switch Count Symmetric T-type Multilevel Inverter with Single and Multiple Switch Open Circuit Fault Tolerant Capabilities

In this paper, a nine-level inverter topology is proposed with the least number of switches and other components for fault tolerant (FT) operation. The proposed fault tolerant topology requires only one additional switch to execute the fault tolerant operation. The proposed topology also results in reduced total harmonic distortion (THD) as compared with other reported fault tolerant topologies for a 9-level output. A detailed analysis of the topology is presented and the fault tolerant operation is demonstrated under any single, double, triple, and quadruple switch faults using MATLAB/ Simulation and OPALRT hardware in loop (HIL) real time simulator. The proposed concept is validated for single and multiple switch faults and R-L load variation on a low scale laboratory hardware set-up.

Fault-Tolerant Control Scheme for the Sensor Fault in the Acceleration Process of Variable Cycle Engine

This paper presents a fault-tolerant control scheme for the sensor fault in the acceleration process of the variable cycle engine. Firstly, an adaptive equilibrium manifold model with multiple inputs and multiple outputs is established. Combined with the Kalman filter bank, sensor fault diagnosis is carried out to realize the diagnosis and signal reconstruction of the engine in the case of a single sensor and double sensor faults. On this basis, isolation and group isolation are used to diagnose sensor faults and reconstruct signal in speed closed-loop control. Then, the control plan of the acceleration process is optimized based on the target shooting method, aiming to simulate the variation of various variables in the engine acceleration process more accurately, so as to verify the feasibility of the sensor fault-tolerant control scheme. Finally, a hardware-in-loop simulation platform is built based on the idea of distributed control, and the fault-tolerant control scheme of the sensor proposed previously is verified based on this platform. The results show that the proposed scheme can accurately diagnose the sensor faults and reconstruct the signal within 0.2 s, and the actual speed can rise from 67.87% to 99.9% in 4 s, ensuring the safe and rapid completion of the acceleration process.

An analysis of FPGA configuration memory SEU accumulation and a preventative scrubbing technique

Reliability in microelectronics is an important factor in high radiation environments, such as in space, particularly in SRAM-based FPGAs where a Single Event Upset (SEU) in the configuration memory can have drastic effects on the connections of implemented designs. As technology advances and components reduce in size with lower operating powers, SEUs can occur more frequently. An SEU in the configuration memory is permanent unless the associated bit is rewritten either by a full reconfiguration or configuration memory scrubbing. In this paper we discuss a phenomenon that we call secondary critical bits (SCBs), in which certain bits or frames have a chance of causing functional failures if an SEU already exists in the system without a functional failure, and a new metric, frame criticality that can be used for a more fine-grained analysis of a designs reliability. We present a novel frame based statistical double bit fault injection method to analyse the frame criticality in a feasible amount of time. Also presented is a passive configuration memory scrubbing scheme that offers greater protection against this phenomenon compared with traditional blind techniques with improvements up to 65%, for higher SEU rates and more sensitive components.

An experimental study of the behavior of a model variable refrigerant flow system with common faults

Variable refrigerant flow (VRF) systems faults are inevitable due to installation errors, degradation, and other reasons. It is of great value to quantitatively understand the impact of faults on VRF systems performance and to clarify the changing trends of variables under different types of faults through experiments. In particular, the experimental analysis of simultaneous faults situations is helpful to improve the fault detection and diagnosis technology of VRF systems. There have been some previous experimental studies on the impact of faults, but none of them concerns modern VRF systems and their simultaneous faults. This paper presents results from a laboratory study of a VRF system with different types of faults. It provides the first published results of combinations of triple simultaneous faults, in addition to previously untested types of double simultaneous faults. The quantitative impact of the three crucial performance parameters, e.g. cooling capacity, system power, and COP, of the system under different faults has been analyzed. In addition, the quantitative influence and variation trend of system parameter variables during single fault and simultaneous fault are summarized. Results show that the outdoor fouling fault has the greatest impact, which can cause a 47.6% COP drop and 80.27% cooling capacity reduction. The influence of the simultaneous fault on the variable trend is superimposed and offset, but the trend influence of some faults also has a dominant characteristic.

Structural characteristics and mechanism of the Hengshui accommodation zone in the southern Jizhong subbasin, Bohai Bay basin, China

Based on seismic data, we document the differences in the geological structure and evolution on the two sides of the Hengshui Accommodation Zone (HAZ), identify the timing of faulting on faults, and analyze the mechanism of the HAZ. The northern part of the HAZ is characterized by a half-graben controlled by double detachment faults with opposite dips, and the southern part of the HAZ is characterized by a compound half-graben controlled by a single detachment fault with multiple faults. The structural evolution of the southern Jizhong subbasin can be divided into the following five stages: the basement evolution stage; Rift Episode I (Ek-Es4); Rift Episode II (Es3–Es2); Rift Episode III (Es1-Ed); and the Postrift stage (Nm-Ng). Three segments were identified along the HAZ, namely, the Xinle Anticline (XLA), the Ningjin Segment (NJS) and the Hengshui Transfer Fault (HSTF). The XLA is a transverse anticline produced by the fault section of the Taihang Mountain Piedmont Fault (TMPF). The NJS is a transfer fault formed by the differential extension of the Ningjin Fault. As a major part of the HAZ, there are obvious differences in the faults on both sides of the HSTF, and NE-trending Cenozoic faults were mainly on its north side, while the NNE-trending faults formed in the basement stage were distributed on its south side. During the basement evolution stage, NNE-trending basement faults and the HSTF developed by WNW extension. During Rift Episode Ⅰ (Ek-Es4), under the NW extension, NE-trending fault segments formed, and pre-existing faults were reactivated. During Rift Episode Ⅱ (Es3–Es2), pre-existing faults were subjected to oblique extension, and the NE-trending fault segments on both sides of the HSTF grew into the main fault and intersected with the HSTF. From Rift Episode III (Es1-Ed) to the present, some pre-existing faults have been reactivated, and many new secondary faults in the basin have finally produced the present structural pattern. These results suggest that the continuous transfer of the regional stress field during the Mesozoic and Cenozoic was the driving force for the formation and evolution of the HAZ.

Event-triggered fault detection for nonlinear semi-Markov jump systems based on double asynchronous filtering approach

The event-triggered fault detection problem for nonlinear semi-Markov jump systems constructed by Takagi–Sugeno fuzzy approach is studied in this paper. Owing to that the premise variables and the modes are usually mismatched for both the filter and the plant in actual network environment, i.e., the double asynchronous phenomenon, a novel double asynchronous fault detection filter is designed to take the place of the traditional filter and tackle the fault detection problem for fuzzy semi-Markov jump systems. Particularly, the event-triggered scheme is considered to reduce the waste of communication resources, which gives rise to the premise variables asynchronous phenomenon for the plant and the filter. The modes information of the fuzzy semi-Markov jump systems is not always instantaneously accessible, which leads to the mode asynchronous phenomenon for the plant and the filter. This mode asynchronous phenomenon is described by a hidden semi-Markov model. Based on Lyapunov stability theory, the sufficient conditions are developed to ensure that the system not only is stochastically stable and meets an H∞ performance, but also can make sure that the filter gains could be captured. Finally, an illustrative tunnel diode circuit example is provided to show the effectiveness of proposed approach.

(DSF)n-graphene: a carbon semimetal with double stacking faults

The grain boundary of (DSF)n-graphene is constructed by a double stacking fault. The Dirac cone of (DSF)n-graphene is mainly contributed by the grain boundaries. The surface states prove that (DSF)n-graphene have nontrivial topological features.

Diode Open-Circuit Fault Research on the Parallel-Connected 24-Pulse Rectifier With DC-Side Passive Harmonic Reduction Circuit

Multipulse rectifiers (MPRs) with dc side passive harmonic reduction circuits often have lower input current total harmonic distortion (THD) values and power losses, that fulfill power requirements for many industrial occasions. In addition to normal operation properties, fault tolerance is another aspect closely related to overall performance of MPRs. This article takes a common parallel-connected 24-pulse rectifier as an example, researches its operation characteristics and fault tolerance under diode open-circuit fault conditions. Operation modes under single or double diodes open-circuit fault in the main circuit, as well as diode open-circuit fault in the dc side harmonic reduction circuit are discussed in details. It can be determined that load voltage is the characteristic parameter that directly reflects the fault information. Related simulation and experimental verifications are performed, all results are consistence with theoretical waveforms. This article provides useful guidance for fault handling and clarifies factors related to the reliability of MPRs, which are helpful for novel MPRs design.

Feminist activism in Austria – and its way to escape a spiral of silencing and inner exile

Recent political developments in European countries indicate a shift to the political right and an increase in attacks on gender equality. This political change has also started to influence scholarly work and teaching of equality, diversity, and inclusion (EDI) topics in Austria and has led to its re-contextualization by pinpointing the rising counter forces to EDI issues. This text fills a knowledge gap on the EDI counter forces and the experiences of EDI experts and researchers by exploring their increasing silence in these times of change to the right. Based on a participatory action research project, the paper shows that a (self-)reflection on silence opens a demand for recollecting in ‘safe spaces.’ The paper demonstrates that these spaces do not only allow a reflection on how to overcome a double fault line triggered by losing previous EDI supporters and a newly invigorated gender equality opposition. These spaces also give support in escaping the spiral of silence and inner exile. The text discusses strategies addressed in these safe spaces to counter a retraction of existing gender equality policies.

Research on thermoeconomic fault diagnosis for marine low speed two stroke diesel engine.

To satisfy the requirements of low fuel consumption, low emission, and high efficiency of the shipping industry, marine diesel engines are developing in the direction of automation and energy-saving, which increases the possibility and complexity of marine diesel engine failures. A one-dimension thermodynamic model for the marine diesel engine is built with AVL Boost software. The model is applied to a low-speed two-stroke 6S50MC diesel engine, and the error between the main performance parameters obtained by simulation and the test bench data is less than 3% under 100% and 75% load. Based on the model, 6 typical single faults and many typical double faults concomitant phenomena of diesel are reproduced. Based on the second law of thermodynamics, the exergy flow among the components and the external environment is analyzed. The thermoeconomic model of a marine diesel engine is established where the "fuel" and "product" of the components are defined according to their function. The fault diagnosis results show that the effects of faults generally propagate through the diesel engine system and affect the behavior of several components, resulting in induced malfunction in normal components. Therefore the malfunction MFi of each component is the superposition of the intrinsic malfunction and the induced malfunction according to the malfunction and dysfunction analysis. The thermoeconomic fault diagnosis method can be used to narrow the search range of abnormal components though it cannot accurately locate the fault.

A Method for Parametric and Catastrophic Fault Diagnosis of Analog Linear Circuits

A universal method for single parametric and catastrophic fault diagnosis of analog linear circuits is presented in this paper. The methodology is based on fundamental laws governing linear circuits and methods of their analysis. The method involves creating models of the faulty elements, both passive and active, including current and voltage sources and applying an appropriately modified node method. This enables the creation of simple formulas to define the parameters of the faulty elements. Some measurement data must be collected during the course of the diagnostic test performed in the frequency domain and certain computation results obtained in the before-test-process. The method achieves all of the objectives of fault diagnosis: detection, location, and estimation of the faulty value. In 88.48%, the method correctly identifies the fault and estimates its value, but in 6.47%, the actual fault is accompanied by a virtual fault. The method is adapted to real conditions to improve the practical relevance and can be directly extended to double fault diagnosis. Six numerical examples are presented to illustrate the method.

Geometry and kinematics of the western part of the NE Qaidam Basin: Implications for the growth of the Tibetan Plateau

Based on field geology, seismic reflection profiling data and isopach maps, the structural deformation pattern, timing of deformation, and mechanism of formation of the western part of the NE Qaidam Basin (including the Pingtai Uplift, Lenghu and Eboliang structural belts) during the Mesozoic and Cenozoic eras have been investigated. Several anticlines in the Lenghu and Eboliang structural belts are generally characterized by double fault systems at different structural levels. At shallower crustal levels, a thrust fault system dominates and at lower levels positive flower structures accommodate oblique shortening, and these are mainly separated by weak strata layers in the Upper Xiaganchaigou Formation, of late Eocene age. Left-step en echelon distributed normal faults and trailing extensional imbricate fan structures consistently demonstrate that the Lenghu and Eboliang structural belts are dominated by dextral transpressional deformation. The western part of the NE Qaidam Basin experienced an initial stage of extension in the Jurassic, which was associated with the formation of several NW-striking normal faults. We hypothesize that most of the deep compressional structures and shallow anticlines were formed due to the SW-directed thrusting of the Qilian Shan since the early Eocene, as a far-field effect of the Indo-Asian “hard” collision. The NNE-directed shortening was associated with dextral transpressional deformation within the western part of the NE Qaidam Basin that took place after the deposition of the Shangyoushashan Formation, of middle-late Miocene age. We interpret this phase of deformation to have been an integral part of the pulsed growth of the whole Tibetan Plateau.

Serve efficiency development in women’s vs. men’s professional tennis

PurposeThe purpose was to identify possible gender-specific differences in long-term serve efficiency development in professional women’s and men’s tennis.MethodsThe analyses focused on 2 approaches: (1) total tournament comparison and (2) 2&lt;sup&gt;nd&lt;/sup&gt; tournament week vs. 1&lt;sup&gt;st&lt;/sup&gt; tournament week comparison. The data include all single matches at the Wimbledon Championship between 2002 and 2015 (ladies: &lt;i&gt;n&lt;/i&gt; = 1771, gentlemen: &lt;i&gt;n&lt;/i&gt; = 1772).ResultsThe findings showed significant development differences in favour of elite men over elite women in both comparisons. Regarding the total tournament comparison, men’s development of 2&lt;sup&gt;nd&lt;/sup&gt; serve points won (&lt;i&gt;p&lt;/i&gt; &lt; 0.001; &lt;i&gt;r&lt;/i&gt; = 0.86), 1st serves in (&lt;i&gt;p&lt;/i&gt; &lt; 0.05; &lt;i&gt;r&lt;/i&gt; = 0.72), and double fault (&lt;i&gt;p&lt;/i&gt; &lt; 0.001; &lt;i&gt;r&lt;/i&gt; = 0.85) percentages improved significantly more. As per the 2&lt;sup&gt;nd&lt;/sup&gt; tournament week vs. 1&lt;sup&gt;st&lt;/sup&gt; tournament week comparison, men’s development of 2&lt;sup&gt;nd&lt;/sup&gt; serve points won (&lt;i&gt;p&lt;/i&gt; &lt; 0.05; &lt;i&gt;r&lt;/i&gt; = 0.68) and double fault (&lt;i&gt;p&lt;/i&gt; &lt; 0.01; &lt;i&gt;r&lt;/i&gt; = 0.86) percentages improved significantly more.ConclusionsThe study revealed serve efficiency development advantages for men over women in both comparisons, especially regarding the quality of the 2&lt;sup&gt;nd&lt;/sup&gt; serve, whereas no development advantages in favour of women over men could be observed in any analysed parameter, indicating possible needs to adapt elite women’s coaching.