Open Failure Research Articles

Gas detection in sodium cooled fast reactors: determination of a transfer function

To keep the dependability of Sodium Cooled Fast Reactor, the “clean sodium concept” is demanded, which means that the sodium is free from contamination. The release of fission products is searched for by a contamination measuring system. We need to have a comprehensive description of cladding failures and the detection of contamination, including the failure occurrence on the fuel pin, the transfer process through the sodium and cover gas, the measurement efficiency, etc. We aim to identify the important parameters of physical phenomena, with modelling and simulations based on the return of experiments from past reactors such as PHENIX. There have been a total of 15 open pin failures in PHENIX reactor. Through studying these detected signals, we can get a better physical explanation and description of the evolution of failures. The detection system is related to different stages of the evolution of fuel pin, with different types of fission products, various release mechanism and physical properties. During the evolution of the failed fuel pin, gaseous fission products is released on the first stage of failure and the gas detection system is aimed for the gaseous fission products monitoring. We proposed a quantitative modeling of transfer function to describe the time broadening of the gas release from the fuel pin to the detector. The result matches well with PHENIX experiment data, with the same order of magnitude of the time broadening and the same shape of exponential decreasing. A determination of the transfer function of this gas detection system is validated in this paper.

Temporomandibular Joint Ankylosis Surgery in Children

A variety of techniques have been described in the literature for the treatment of temporomandibular joint ankylosis. However, 1 of the factors most commonly related to the failure of maintenance mouth opening in the postoperative period is the inadequate excision of the ankylotic mass. Furthermore, the surrounding noble structures, such as the base of the skull, internal maxillary artery, and dental germs, are at risk of being affected during the procedure. For this reason, prototyped guides have been proposed to steer osteotomies and resections of the ankylotic block in the temporomandibular joint. Nevertheless, access to this technology, especially in developing countries, can represent a financial barrier. Therefore, our proposal is to manufacture low-cost surgical cutting guides to increase their applicability.

Design acceptance criteria for operating open-pit slopes: An update

ABSTRACT Open-pit slope engineering involves balancing economic imperatives and risk, where an optimum pit slope design seeks to safely steepen the pit slope angles to minimize the mining of waste, therefore maximizing ore recovery. Open-pit Design Acceptance Criteria (DAC) had been proposed and adopted by industry, and the Guidelines for Open Pit Slope Design, published in 2009, finally provided a consistent set of guidelines. Since the publication of these guidelines, it has been the industry experience that practical DAC requires consideration of multiple levels of design confidence, ranging from highly uncertain greenfield sites to mature operations; the unique nature of consequences associated with open pit wall failures as opposed to other civil and mining structures; and differences between operators’ risk appetite. This article presents the state of practice for inter-ramp and overall open-pit slope design in the mining industry and develops flexible DAC for operating pits that addresses the considerations outlined. The criteria are rooted in robust risk tolerance principles, previously adopted criteria, a database of open-pit designs, and mathematical validation for criteria in terms of both Factor of Safety (FoS) and Probability of Failure (PoF).

Transient thermal‐hydraulic analysis of heat pipe cooled passive residual heat removal system of molten salt reactor

As one of the representatives of fourth generation nuclear reactors, molten salt reactor technology has become the research focus worldwide. Higher passive safety requirements have been put forward for the nuclear reactor systems. In this paper, a conceptual design of a passive residual heat removal system for the molten salt reactor is presented and the mathematical and physical models are established. Based on FORTRAN programming language, the passive residual heat removal system analysis code is developed and validated. The code is used to analyze the safety of molten salt reactor under accident conditions, including unprotected reactivity introduction accident, unprotected overcooling, unprotected loss of flow, opening failure of the frozen valve and the startup accident of partial heat pipes. The results show that the passive residual heat removal system of molten salt reactor can discharge fuel salt decay heat effectively within 200 hours and ensure that the molten salt reactor to operate safely under all accident conditions. Above all, the system has good passive safety performance. The proposed passive residual heat removal system can satisfy the safety requirement of molten salt reactor. The feasibility of the conceptual design of the heat pipe cooled passive residual heat removal system is theoretically verified.

Optical Beam-Based Defect Localization Methodologies for Open and Short Failures in Micrometer-Scale 3-D TSV Interconnects

We report laser-based fault isolation methodologies for the localization of open and short failures in $1 \times 5\,\,\mu \text{m}$ via-last through-silicon via (TSV) structures for 3-D system-on-chip (SoC) integration. Due to the photosensitive TSV interconnect capacitance, observation of the photocapacitance response enables nondestructive localization of metallization ruptures. A light-induced capacitance alteration (LICA) measurement is demonstrated on an open failed $1 \times 5\,\,\mu \text{m}$ TSV chain structure with a manufacturing defect. We validate our measurements with active voltage contrast imaging in the scanning electron microscope (SEM) and focused-ion beam (FIB) cross sectioning. Second, TSV dielectric defects generating leakage current between TSV and substrate (i.e., short defects) are detected and localized by sensing the laser-induced TSV photocurrent. An optical beam-induced current (OBIC) measurement is demonstrated on electrically overstressed TSV array structures whereby multiple TSVs are configured in a parallel arrangement. By applying a selective substrate removal process, we can expose the full TSV array and perform optical and tilted SEM inspection and reveal pinhole defects in the TSV liner. We further investigate the effect of breakdown energy on the pinhole formation, relate electrical measurements to SEM inspection, and confirm our results by FIB cross sectioning.

Increased expression of the MALE STERILITY1 transcription factor gene results in temperature-sensitive male sterility in barley.

Understanding the control of fertility is critical for crop yield and breeding; this is particularly important for hybrid breeding to capitalize upon the resultant hybrid vigour. Different hybrid breeding systems have been adopted; however, these are challenging and crop specific. Mutants with environmentally reversible fertility offer valuable opportunities for hybrid breeding. The barley HvMS1 gene encodes a PHD-finger transcription factor that is expressed in the anther tapetum, which is essential for pollen development and causes complete male sterility when overexpressed in barley. This male sterility is due at least in part to indehiscent anthers resulting from incomplete tapetum degeneration, failure of anther opening, and sticky pollen under normal growth conditions (15 °C). However, dehiscence and fertility are restored when plants are grown at temperatures >20 °C, or when transferred to >20 °C during flowering prior to pollen mitosis I, with transfer at later stages unable to rescue fertility in vivo. As far as we are aware, this is the first report of thermosensitive male sterility in barley. This offers opportunities to understand the impact of temperature on pollen development and potential applications for environmentally switchable hybrid breeding systems; it also provides a 'female' male-sterile breeding tool that does not need emasculation to facilitate backcrossing.

Open source computer vision-based layer-wise 3D printing analysis

The paper describes an open source computer vision-based hardware structure and software algorithm, which analyzes layer-wise 3-D printing processes, tracks printing errors, and generates appropriate printer actions to improve reliability. This approach is built upon multiple-stage monocular image examination, which allows monitoring both the external shape of the printed object and internal structure of its layers. Starting with the side-view height validation, the developed program analyzes the virtual top view for outer shell contour correspondence using the multi-template matching and iterative closest point algorithms, as well as inner layer texture quality clustering the spatial-frequency filter responses with Gaussian mixture models and segmenting structural anomalies with the agglomerative hierarchical clustering algorithm. This allows evaluation of both global and local parameters of the printing modes. The experimentally verified analysis time per layer is less than one minute, which can be considered a quasi-real-time process for large prints. The systems can work as an intelligent printing suspension tool designed to save time and material. However, the results show the algorithm provides a means to systematize in situ printing data as a first step in a fully open source failure correction algorithm for additive manufacturing.

Empirical Research on the Application of Online Teaching in Chinese Colleges and Universities Under the Situation of Novel Coronavirus Pneumonia Prevention and Control

At the turn of 2019-2020, a new epidemic broke out in China. China has entered the critical stage of epidemic prevention and control. And The severe situation has led to the failure of normal opening of new semester in Chinese colleges and universities. In order to effectively guarantee the education, teaching and talent cultivation in colleges and universities, the Ministry of education of China has rapidly put forward the requirements of launching online teaching. Therefore, under the situation of Novel Coronavirus Pneumonia (Hereinafter referred to as 2019-nCoV) prevention and control, online teaching in Chinese colleges and universities is widely used and develops rapidly. However, the demand for online education has been released in a short time and on a large scale, and each online teaching platform has encountered unprecedented pressure and challenges. In this regard, based on the situation of 2019-nCoV prevention and control in China, this paper demonstrates how the Chinese government deploy online teaching in an all-round way with specific measures, how the Chinese colleges and universities implement massive online teaching quickly, how teachers and students adapt to online teaching quickly. At the same time, this paper carries out empirical analysis to show the process and effectiveness of online teaching in Chinese colleges and universities in the unprecedented state of 2019-nCoV prevention and control with specific examples. On this basis, it analyzes and summarizes the advantages and disadvantages, so as to facilitate the later improvement and provide reference.

On‐site detection of bypass circuit opening failure in photovoltaic array under power generation operation

AbstractTo ensure the long‐term reliability of photovoltaic systems (PVSs), periodical inspections are necessary. Despite the risk of severe temperature rise, bypass circuit open‐circuit (BPC‐OC) failure has attracted low research interest compared with other types of failure. This paper presents the pulsed light irradiation (PLI) method for robust BPC‐OC failure detection that eliminates the need to switch off the power generation operation of the PVS. The proposed method detects the BPC‐OC failure of the solar cell string by measuring the modulated current induced by local PLI. Electrical circuit simulations as well as indoor and outdoor experiments are performed to verify the performance of the proposed method. Results of the outdoor experiment show that the PLI method performs well in a real PVS under power generation operation. Finally, the advantages and disadvantages of the proposed method are summarized.

A phase field computational procedure for electromigration with specified contact angle and diffusional anisotropy

Electromigration in electrical interconnects with high current density causes voids to form and grow near the cathode. These voids can possibly grow large enough to cause open circuit failure. The simulation of electromigration void nucleation and growth is challenging because of the complex interaction of electrical, thermal and mechanical fields that lead to the observed voids. In this paper, a phase-field approach is developed to study void growth due to electromigration taking into account diffusional anisotropy and specified contact angle. Consideration of anisotropy and contact angle is critical in applications including electronic assemblies that most commonly use Sn-based solder interconnects. In such systems, Sn exhibits significant anisotropy in its self-diffusivity, which assumes importance in small solder joints that are known to contain only a few grains. Furthermore, the contact angle at the void-bonding pad-solder triple junction is known to influence the void size and shape. To the best of the authors’ knowledge, only anisotropy in surface diffusivity has been considered in phase-field electromigration literature, whereas the contact angle at a triple junction has not been considered. The developed phase-field model incorporates effects of both contact angle and anisotropy in self-diffusivity. The model is used to simulate systems with different contact angles and dominant directions of diffusion. It is observed that diffusional anisotropy plays a more dominant role in failure, while the contact angle dictates evolution of the shape of voids.

In-operando fatigue behavior of gold metallization lines on polyimide substrate

Although in-situ monitoring of electrical resistance of polymer-supported thin films during a mechanical test is frequently used, the impact of the magnitude of electric current on material behavior in such experiments remained unknown. Here, we report on cyclic straining of polymer-supported gold metallization lines under direct current of different magnitudes. Fatigue damage in form of localized extrusions becomes more pronounced with increasing current as a result of Joule heat and material softening. After a critical current value is reached, crack propagation results in a local decrease of line cross-section leading to thermal runaway and open circuit failure.

Failure Analysis of Metallic Materials: Morphological Characteristics, Mechanisms and Laboratory Investigation

Morphological analysis, characteristics and modes/mechanisms of metallic materials (components) failure particularly in service have been reviewed and discussed. Firstly, the various investigation steps and analytical methods are expressed, while various failure examples are discussed. The investigation techniques range from visual inspection, non-destructive testing to electron microscopy and chemical analysis methods. Secondly, laboratory investigative analysis of failed Al wire of 1120 grade was performed with scanning electron microscopy and energy dispersive spectroscopy (EDS) techniques to reveal availability of second-phase particles (impurities) at representative areas of interest for the largest open microscopic failure and inside surface feature of the failed Al wire at different locations inside and near the edge of the failed cracks. The mode of failure was determined to be brittle failure, while the surrounding matrix presents a feature of mixed brittle and ductile failure. EDS analysis shows O2 in addition to the base Al which is an indication of Al2O3. The peak for Cl was also present. This impurity within the aluminium matrix is responsible for weakening the Al substrate structure which yields under high stress.

A real-time monitoring system based on ZigBee and 4G communications for photovoltaic generation

A novel real-time monitoring system for photovoltaic (PV) generation is presented in this paper. Internet of Things (IoT) integrated with cloud servers and terminal applications allow the remote monitoring of centralized or distributed photovoltaic systems. The proposed system could realize the networking communication of multiple nodes based on ZigBee, and upload the operational data to the cloud server via a 4G communications network. Then, the server selects three-phase current as the sample sets from the uploaded data to set up a composite current characteristic combining wavelet packet energy with waveform parameter, and establishes a fault diagnosis model based on the probabilistic neural network to analyze the health status of the PV inverter online. This method requires little sampling frequency without an extra signal and saves the cost of local devices by placing online diagnostics on the server-side. In addition, the user could query and store the running information of the PV systems through the personal computer-side web or mobile phone with remote control. This article presents the hardware design of ZigBee and the 4G module, and composition of the diagnosis model for open circuit failure of the PV inverter through the cloud server, building the user software at the application layer. The final experimental results show that the proposed system has better communication performance and higher diagnostic accuracy in real-time monitoring.

The necessity of anterior knowledge exchange activities for technological collaboration and innovation performance improvement

The adoption of open innovation does not guarantee technological innovation. Many companies have nonetheless implemented open innovation, but success and failure are repeated in the process leading to product innovation performance. In this study, the important elements of technological collaboration, a representative type of open innovation, that can affect product innovation performance were investigated. Also, a structural equation was used to verify the technological collaboration strategy required by the Korean manufacturing industry. In particular, the perspectives on the necessities of anterior knowledge exchange activities and appropriate appropriability mechanisms were considered. The verification results of this study were as follows. First, anterior knowledge exchange activities had a positive effect on the subsequent technological collaboration and product innovation performance, and it was found that science, technology, and innovation (STI)-based knowledge was more effective. Second, increased doing, using, and interacting (DUI)-based knowledge exchange activity resulted in diminished STI-based knowledge effectiveness. Third, the application of informal appropriability mechanisms contributed positively to both technological collaboration and product innovation performance. Based on the verification results of this study, the strategic direction for maximising technological collaboration and product innovation performance was presented for Korean manufacturing companies.

The necessity of anterior knowledge exchange activities for technological collaboration and innovation performance improvement

The adoption of open innovation does not guarantee technological innovation. Many companies have nonetheless implemented open innovation, but success and failure are repeated in the process leading to product innovation performance. In this study, the important elements of technological collaboration, a representative type of open innovation, that can affect product innovation performance were investigated. Also, a structural equation was used to verify the technological collaboration strategy required by the Korean manufacturing industry. In particular, the perspectives on the necessities of anterior knowledge exchange activities and appropriate appropriability mechanisms were considered. The verification results of this study were as follows. First, anterior knowledge exchange activities had a positive effect on the subsequent technological collaboration and product innovation performance, and it was found that science, technology, and innovation (STI)-based knowledge was more effective. Second, increased doing, using, and interacting (DUI)-based knowledge exchange activity resulted in diminished STI-based knowledge effectiveness. Third, the application of informal appropriability mechanisms contributed positively to both technological collaboration and product innovation performance. Based on the verification results of this study, the strategic direction for maximising technological collaboration and product innovation performance was presented for Korean manufacturing companies.

Research on Operation of Low-Speed and High-Torque Module Combined Stator Permanent Magnetic Fault-Tolerant Motor With Unequal Span Winding

Permanent magnetic fault-tolerant motors have been developed rapidly due to their high reliability and have been widely used in many special fields. Compared with the conventional module fault-tolerant motor, the module combined stator permanent magnetic fault-tolerant motor (MCS-PMFTSM) with unequal span winding has two sizes of span coils in each operation module, which realizes the electrical decoupling and mechanical decoupling between the module motors and solves the problem that the span of the double-layer winding of the conventional modular fault-tolerant motor can only be 1. Winding parameters of the unequal span are calculated, on the basis of which the operation performance of MCS-PMFTSM can be analyzed. The performance of MCS-PMFTSM in the normal operation and three failure operations (open circuit failure, Short circuit fault, concurrent failure) are analyzed by finite element method, which proves that it has good fault tolerance. The 12kW100r/min MCS-PMFTSM prototype is tested to verify the correctness of the analysis method and the rationality of the proposed MCS-PMFTSM.

Study on judgment method for open failure of bypass diode of solar cell module using thermal image

Study on judgment method for open failure of bypass diode of solar cell module using thermal image

Dependable and Secure Voting Mechanism in Edge Computing

Edge computing is a distributed computing paradigm that encompasses data computing and storage and is performed close to the user, efficiently guaranteeing faster response time. This paradigm plays a pivotal role in the world of the Internet of Things (IoT). Moreover, the concept of the distributed edge cloud raises several interesting open issues, e.g., failure recovery and security. In this paper, we propose a system composed of edge nodes and multiple cloud instances, as well as a voting mechanism. The multi-cloud environment aims to perform centralized computations, and edge nodes behave as a middle layer between edge devices and the cloud. Moreover, we present a voting mechanism that leverages the edge network to validate the performed computation that occurred in the centralized environment.

Fluid dynamic forces in the main steam pipeline of thermal power plant upon stop valves closure

A steam turbine trip is followed by a prompt closure of stop valves in front of the turbine and consequently to a pressure rise in the main steam pipeline. This steam hammer transient leads to the generation of intensive fluid dynamic forces that act along the pipeline axis and induce additional dynamic loads on the main steam pipeline. It is a common practice to assume a simultaneous closure of all stop valves in the safety analysis of the main steam pipeline. In the present paper computer simulations and analyses of the fluid dynamic forces are performed for several scenarios that take into account the possibility of delayed closure of the stop valve in front of the turbine. The influence of the failure of the steam by-pass line opening is considered too. The results show that the delay of the stop valve closure increases the maximum intensity of fluid dynamic force in the pipeline segment in front of the stop valve and decreases the intensity of fluid dynamic forces in segments along the pipeline. The failure of the by-pass line to open leads to prolonged steam pressure and fluid dynamic forces oscillation in pipeline segments. The simulations were performed with the in-house computer code based on the method of characteristics for the solving of the hyperbolic system of PDE that represent the mass, momentum and energy balance equations of the 1-D, compressible and transient fluid-flow. The obtained results are a support to safety analyses of thermal power plants under transient conditions.

TSHD ship opening simulation by discrete element method

This article studies a Split Trailing–Suction Hopper Dredger (Split TSHD) with longitudinally-split hull, which symmetrically opens for gravity-driven unloading of the cargo while being exposed to various environmental conditions. Regular and failure hull openings are numerically simulated to investigate the ship stability and safety of cargo discharge procedures. Unsteady simulations of discharging were performed by the Discrete Element Method, while the ship hydrostatic properties are calculated using Radial Basis Functions. The dynamics of the righting moment and arm are simulated, which are affected by the cargo dynamics and the loss of displacement. Results of the numerical simulations indicate that cargo dynamics during the discharge should not be ignored, as it affects ship’s transverse stability. An incoming wave combined with an opening failure of the hull could lead to serious loss of transverse stability.