Machine Safety Research Articles

Summary of the 13th IAEA technical meeting on plasma control systems, data management and remote experiments in fusion research

This report summarizes the contributions presented at the IAEA technical meeting on 13th IAEA technical meeting on plasma control systems, data management and remote experiments in fusion research, hosted by UKAEA and held virtually, on 5–8 July 2021. The meeting brought together 90 experts from nuclear fusion research sites worldwide. The main topics of the meeting were plasma control; machine control, monitoring, safety and remote manipulation; data acquisition and signal processing; database techniques for information storage and retrieval; advanced computing and massive data analysis; remote participation and virtual laboratory; and fast network technology and its application.

Multivariate Lipschitz Analysis of the Stability of Neural Networks

The stability of neural networks with respect to adversarial perturbations has been extensively studied. One of the main strategies consist of quantifying the Lipschitz regularity of neural networks. In this paper, we introduce a multivariate Lipschitz constant-based stability analysis of fully connected neural networks allowing us to capture the influence of each input or group of inputs on the neural network stability. Our approach relies on a suitable re-normalization of the input space, with the objective to perform a more precise analysis than the one provided by a global Lipschitz constant. We investigate the mathematical properties of the proposed multivariate Lipschitz analysis and show its usefulness in better understanding the sensitivity of the neural network with regard to groups of inputs. We display the results of this analysis by a new representation designed for machine learning practitioners and safety engineers termed as a Lipschitz star. The Lipschitz star is a graphical and practical tool to analyze the sensitivity of a neural network model during its development, with regard to different combinations of inputs. By leveraging this tool, we show that it is possible to build robust-by-design models using spectral normalization techniques for controlling the stability of a neural network, given a safety Lipschitz target. Thanks to our multivariate Lipschitz analysis, we can also measure the efficiency of adversarial training in inference tasks. We perform experiments on various open access tabular datasets, and also on a real Thales Air Mobility industrial application subject to certification requirements.

Acoustic Emission Based Fault Detection of Substation Power Transformer

Fault detection of Substation Power Transformer by Non-contact measurement is important for the safety of machines, instruments, and human beings. To make non-contact measurement as convenient as possible, it is desirable that efficient algorithms based on AE (acoustic emission) discrimination are developed. This paper presents a system for quick and effective fault detection of substation power transformer, based on AE signals collected by non-contact single microphones. In the experiment, collected data were preprocessed in multiple ways and three machine learning algorithms were designed based on classifiers (Convolutional Neural Network (CNN), support vector machine (SVM), and k-nearest neighbors (KNN) algorithm) trained and tested by a tenfold cross-validation technique. After comparison among the designed classifiers, the results show the two-dimensional principal component analysis (2DPCA) preprocess combined with SVM achieved the best comprehensive effectiveness.

Cationic Lignocellulose Nanofibers from Agricultural Waste as High-Performing Adsorbents for the Removal of Dissolved and Colloidal Substances.

The accumulation of dissolved and colloidal substances (DCS) in the increasingly closed paper circulating water system can seriously lower the productivity and safety of papermaking machines, and it has been a challenge to develop an adsorbent with low cost, high adsorption efficiency and large adsorption capacity for DCS removal. In this study, cationic lignocellulose nanofibers (CLCNF) were obtained by cationic modification of agricultural waste bagasse in deep eutectic solvents (DES) followed by mechanical defibrillation, and then CLCNF were employed as an adsorbent for DCS model contaminant polygalacturonic acid (PGA) removal. CLCNF was characterized by transmission electron microscopy, Fourier transform infrared, elemental analysis, X-ray diffraction, and thermogravimetric analysis. The analytical results confirmed the successful preparation of CLCNF with 4.6–7.9 nm diameters and 0.97–1.76 mmol/g quaternary ammonium groups. The effects of quaternary ammonium group contents, pH, contact time and initial concentration of PGA on the adsorption were investigated in a batch adsorption study. According to the results, the cationic modification significantly enhanced the adsorption of PGA by CLCNF and the adsorption performance increased with the increase of the quaternary ammonium group contents. The adsorption of PGA on CLCNF followed the pseudo-second-order and the fitted Langmuir isotherm model. The adsorption showed fast initial kinetics and the experimental maximum adsorption capacity was 1054 mg/g, which is much higher than PGA adsorbents previously reported in the literature. Therefore, CLCNF with high cationic group content developed in this paper is a promising adsorbent for DCS removal.

Development of a Hydraulic System for the Automatic Expansion of Powered Roof Support

A mechanical support in a longwall complex requires proper supervision and control of operating parameters because it is responsible for the safety of machines and workers. Its main functions are to protect the excavation against the adverse effects of rock mass and to move it along with the operational progress of the shearer and the scraper conveyor. In the era of Industry 4.0 as well as green economy and sustainable development, the development of machines and devices included in the longwall complex is an important area of invention. When it comes to the mechanical support included in the longwall complex, the authors propose changes to the hydraulic control system. The main purpose of the work was to develop a system that can automatically expand the legs of the powered support. Tests were carried out under real conditions while equipping the support section with a prototypical hydraulic system and with a system monitoring the correct operation of the prototype. This article presents the development of a prototypical installation under real conditions for testing on a longwall. The innovative solution proposed by the authors consisted of introducing a prototypical double valve block into the hydraulic system of the housing, which enables the function of automatic section expansion. The authors proposed a solution aimed at shortening the work time of the powered-support-section operator. The research results made it possible to evaluate the usefulness of the proposed solution. This type of solution can be considered technical support in the process of coal mining in an underground mine. Analysis presented in this paper, along with results from research conducted and its conclusions, can be of practical help to enclosure users to improve reliability and achieve optimal performance.

Second-order Iterative Time-rearrangement Synchrosqueezing Transform and its application to rolling bearing fault diagnosis

Rolling bearings are key components in rotating machines, and their health condition is an important guarantee for the safety of the whole machine. In order to extract fault features of rolling bearings more accurately, a novel signal processing method named Second-order Iterative Time-rearrangement Synchrosqueezing Transform (2-ITSST) with a fast algorithm is proposed in this paper. Firstly, based on Time-reassigned SynchroSqueezing Transform (TSST), the approximation order is increased from the first order to the second order. Then, multiple iterations are conducted to calculate a more accurate group delay (GD) estimation operator. After that, the rearrangement operation is carried out to maximize the concentration of energy near the time-frequency (TF) ridgeline and obtain the result with higher TF aggregation. Lastly, the fast algorithm for 2-ITSST is introduced to overlap TF matrices into segments, which effectively reduced the computational complexity and ensured the TF aggregation of impact signal energy. Meanwhile, in order to make 2-ITSST more efficiently applied in bearing fault diagnosis, impulse extraction method is introduced to extract useful impulse features from the signal processed by 2-ITSST algorithm, and then the bearing fault frequency can be accurately extracted by envelope spectrum analysis. The effectiveness of the proposed method is verified by simulation and experimental studies.

Sajber fizički sistemi za bezbednost na radu u industrijskim postrojenjima - mogućnosti i izazovi

In last decade, many Cyber Physical Systems CPSs for occupational safety have been developed within research programs funded by national and transnational bodies. Many of them are now ready for the market. The paper focuses on the industrial sectors, where the safety of the worker and the safety of machines, equipment and processes are linked each other. The papers proposes to safety managers criteria and suggestions for choosing appropriate CPS for seizing the great opportunities for safety improvement. The paper discusses a few issues, including cybersecurity and privacy, which are critical for a successful implementation of the CPSs in occupational safety. Safety Management System SMS, in particular, must be adequate to collect the amount of data generated by many sensors distributed in work ambient and worn by workers.

Comprehensive Remaining Useful Life Prediction for Rolling Element Bearings Based on Time-Varying Particle Filtering

The remaining useful life (RUL) prediction of rolling element bearing has attracted substantial attention due to its importance in improving reliability and safety of machines. Particle filter (PF) algorithm is widely utilized to track the degradation process of mechanical equipment in RUL prediction. In engineering applications, due to the poor consistency of bearings, the classical PF model with a certain model finds it difficult to deal with bearings with different degradation trends, resulting in poor generalization ability. Therefore, a time-varying PF (TVPF)-based comprehensive RUL (CRUL) prediction model is developed in this article. In the model, a TVPF algorithm is constructed by an adaptive selection rule and sliding window, it has the capability to select the optimal state model with a sliding window, according to the characteristics of the data, and track the degradation state of bearings with different degradation trends; meanwhile, a global/local information fusion (GLIF) technique is proposed for comprehensively considering the overall information and the latest degraded state of the rolling bearings. The effectiveness of the proposed method is verified by two datasets with different degradation trends, respectively. The comparative study indicates that the proposed TVPF algorithm outperforms the other state-of-art methods in RUL prediction and system prognosis with respect to better accuracy and robustness.

STUDY AND EXPERIMENT ON THE OPERATIONAL ADAPTABILITY OF SLOPE CORN HARVESTERS

Studies on the operational adaptability of slope corn harvesters on hilly slopes are of great significance to improve the performance and safety of the whole machine, but there are few studies on this aspect at the present. Therefore, this paper takes a self-developed small sloping land crawler corn harvester as the object combined with the special topography of the hilly sloping land and the technology adopted by the machine to make a mathematical analysis of its operational adaptability on the sloping land. Through the field test, the forward speed of the corn harvester, track wheel spacing and slope angle are used as the test factors, and the harvest loss rate of the corn ear is used as the assessment index to carry out the orthogonal test on the slope land. The analysis of the results based on the Design-expert response surface was completed. The results show that the ear loss rate of the experiment under different conditions is less than 5% of the national standard. The corn harvester has good adaptability to sloped land, which can realize the mechanized operation of corn on the hilly and sloped land, and has good agricultural production application value.

International Standardization of Verification and Validation Methods for Testing Skin Injury Tolerance for Next Generation Machine Safety in Human Interaction

International Standardization of Verification and Validation Methods for Testing Skin Injury Tolerance for Next Generation Machine Safety in Human Interaction

Analysis and Experimental Investigation of Vibration Characteristics of Rotary Platform of Hydraulic Excavator under Complex Working Conditions

The rotary platform is the load-bearing substrate of a hydraulic excavator. The dynamic characteristics of the rotary platform directly affect the reliability and safety of the whole machine of a hydraulic excavator. In this work, the characteristics of the main external excitations acting on the hydraulic excavator such as the engine excitation, pressure pulsation excitation of the piston pump, inertial excitation of the working device, and road excitation are analyzed. The vibration transmission paths under the action of external excitations are ascertained. A vibration test method for the rotary platform of the hydraulic excavator is proposed. The vibration characteristics of the rotary platform under complex working conditions are researched, and the internal relationships between the vibration characteristics of the rotary platform and the engine excitation, pressure pulsation excitation of the piston pump, and road excitation are analyzed experimentally. The results show that the rotary platform is subjected to different excitations when it is under different working conditions. Moreover, the internal relationships between the dynamic characteristics of the rotary platform and the external excitation characteristics can be discovered by analyzing the vibration signals of the rotary platform, and the dynamic characteristics of the whole machine of the hydraulic excavator can be deeply studied based on the vibration characteristics of the rotary platform.

Conservation conditions of chainsaws and electric chainsaws and safety of the farmers who operate these machines

The increasing use of chainsaws in rural areas has demanded the health of rural producers who operate these machines. Thus, the objective of this work was to evaluate the conservation conditions of chainsaws with a 2-stroke Otto Cycle engine and check if they meet NR12 Annex V, as well as confirm whether users meet NR31 in terms of training for use. With the aid of a questionnaire and visits to farms, 103 chainsaws were verified in six municipalities in the central region of the State of Rio Grande do Sul. After organizing the data in an electronic spreadsheet, descriptive statistics and canonical correlation were performed. The questions were divided into four groups, namely: operational, mandatory machine safety equipment, cutting set, and engine. The conservation condition of the machines was seen as worrisome. This is because it was found that 66.01% of machines did not have a saber guard and 49.51% of these were worn out. In addition, 97.08% of the producers did not take a chainsaw operation course, and 85.44% reported not using Personal Protective Equipment (PPE), therefore, in disagreement with the NR6, NR12 Annex V, and NR31 standards. It was clear the need for the operators to carry out training on the safe use and handling of chainsaws.

Numerical Simulation of New Support Structure for High In-situ Stress Tunnel of Sichuan–Tibet Railway

Existing support technology can easily cause the shield machine to jam. A novel ductile support structure is proposed for large deformation tunnels in soft rock along the whole Sichuan–Tibet railway on the basis of the concept of consuming energy of ductile multilevel yielding support. The design of the support structure is to ensure the safety of the shield machine through the large deformation section of soft rock as quickly as possible. In-situ stress data obtained by hydraulic fracturing measurement method were used as boundary conditions of models. The support structure deformation of front shield tunnelling machine and long-term deformation of corrugated steel primary support, steel waist beam and reinforced concrete secondary lining support system were simulated and analysed on FLAC3D software. The variation of the new support structure under the large deformation of soft rock was predicted. Results show that the force path of ductile multilevel yielding support structure is clear. After the excavation of the tunnel and before the application of the concrete lining support, displacement increment of the primary support structure is large. The latter gradually slows down with time, but it still shows an increasing trend. In terms of total displacement distribution, the displacement in the Z direction is obviously larger than that in the X direction, which is consistent with the actual tunnel deformation characteristics. When the tunnel is in operation for 2, 10, 50 and 100 years, stress concentration is found in the arch foot of the assembled supporting system. This condition is mainly manifested as compressive stress after 10 years and tensile stress between 10 and 100 years.

CURRENT STATE OF SCIENTIFIC AND TECHNICAL DEVELOPMENTS IN THE FIELD OF IMPROVING THE EFFICIENCY OF VIBRATION EQUIPMENT AND TECHNOLOGIES

The article considers the state of scientific and technical developments in the field of improving the efficiency of vibration technology. Production activity in most branches of industrial production is provided by the work of various technological machines and vehicles. The operation of machines, equipment, mechanisms, apparatus and devices in the conditions of the need to ensure high productivity is often accompanied by significant dynamic loads, vibration processes and manifestations of shock interactions of machine elements. Ensuring the reliability and safety of machines requires at all stages of their life cycle serious attention to compliance with certain restrictions on the parameters of the dynamic state of technical objects, the development of methods and means of assessing control and management of dynamic interactions. Modern mechanical engineering is a scientific basis for solving the main problems of machine dynamics, which, in general, is based on scientific potential created by domestic and foreign scientists in the field of theoretical and applied mechanics, theory of mechanisms, dynamics and strength of machines, development of scientific directions in automatic control theory. applied system synthesis, etc. The results of scientific research are reflected in the works of famous scientists. The formed practice of pre-design researches of the created machines, the equipment and the equipment is based on wide use of means of mathematical modeling, application of means of computer engineering. The choice of equipment in production is based on cost, productivity, size, energy consumption, etc. In this regard, there is a question of the need to find and develop new approaches, methods and means to ensure the efficiency and reliability of technological machines and equipment.

Preliminary design of real-time plasma control system for CFETR

The China Fusion Engineering Test Reactor (CFETR), aiming at demonstrating fusion energy production in self-sufficient burning in different advanced operation scenarios, has entered the stage of engineering design and R&D (research and development). The real-time plasma control system (PCS), as a critical system controlling the evolution of plasma parameters that are necessary to operate CFETR, is designed synchronously. The CFETR PCS is composed of system architecture, integrated control algorithms, and two assistant tools PCS-SDP (Software Development Platform) and PCS-VP (Verification Platform) for algorithm development and verification. Taking the steady-state operation and machine safety into account, the requirement and conceptual design of the system architecture of CFETR PCS is introduced in this paper. PCS-SDP, a visual algorithm development platform, has completed the preliminary design and a prototype has been built to validate the design and technical feasibility with the control algorithm development for EAST. PCS-VP is under preliminary design taking ITER PCSSP (Plasma Simulation Platform) design as reference. These two tool platforms will strongly support and accelerate the development of CFETR PCS.

Remaining Useful Life Prediction of Broken Rotor Bar Based on Data-Driven and Degradation Model

Rotating machines such as induction motors are crucial parts of most industrial systems. The prognostic health management of induction motor rotors plays an essential role in increasing electrical machine reliability and safety, especially in critical industrial sectors. This paper presents a new approach for rotating machine fault prognosis under broken rotor bar failure, which involves the modeling of the failure mechanism, the health indicator construction, and the remaining useful life prediction. This approach combines signal processing techniques, inherent metrics, and principal component analysis to monitor the induction motor. Time- and frequency-domains features allowing for tracking the degradation trend of motor critical components that are extracted from torque, stator current, and speed signals. The most meaningful features are selected using inherent metrics, while two health indicators representing the degradation process of the broken rotor bar are constructed by applying the principal component analysis. The estimation of the remaining useful life is then obtained using the degradation model. The performance of the prediction results is evaluated using several criteria of prediction accuracy. A set of synthetic data collected from a degraded Simulink model of the rotor through simulations is used to validate the proposed approach. Experimental results show that using the developed prognostic methodology is a powerful strategy to improve the prognostic of induction motor degradation.

Specifics of modern security requirements for software of electronic machine control systems

The required level of safety of machines and mechanisms is achieved through the use of appropriate safety management systems for industrial equipment, including programmable electronic ones. Such systems usually include a variety of security devices for managing industrial equipment settings. Since electronic control systems are currently considered the most promising control systems in this area, the study of the security parameters of their application support determines the relevance of this study. This study analyses the main requirements of IEC 61508 and IEC 62061 standards for compliance with modern safety requirements of embedded and applied software for electronic control systems of machines and mechanisms. This study proposes an algorithm for step-by-step implementation of software for electronic machine control systems in accordance with basic security standards for both built-in and application software. Testing has been determined as the main method of verification of application software. Based on the results of the analysis, it was found that the specification of security requirements, both built-in and application software, should highlight the necessary characteristics of each subsystem, providing information that allows choosing the equipment that meets existing security requirements. Relevant recommendations are given on the specifics of practical application of these standards.

Ukryte naruszenia bezpieczeństwa w układach automatycznego sterowania procesami technologicznymi

The progressing automation and robotization in the industrial plants as well as the increasing complexity of the control systems of integrated machines make it necessary to constantly improve the functional safety of machines through the correct validation of safety systems. Despite the validation process carried out, the potential software errors may reveal during the usage of the machine as hidden security breaches. The article presents examples of security breaches of real machine tools and attempts to implement solutions of automated mechanisms for detecting security problems. Another aspect of the article is the new approach for detecting hidden security breaches. Using the „digital twin” model of the machine, a program that generates a sequence of events for testing control systems, and the use of a virtual reality (visual verification of the safety programs), it is possible to maximize the functional safety functions of the machine.

Вдосконалення національних стандартів у м’ясній і молочній промисловості

The subject of research is standardization as one of the forms of technical regulation in the food industry of Ukraine, in particular in the production of milk and milk products, meat and meat products, determination of safety and quality parameters of the specified food raw materials and finished products made from those, as well as installations and equipment for the food industry. The purpose of the study is to analyze the state of standardization in the production of dairy and meat products, highlight the existing problems and possible ways to solve them, as well as outline the role that the Technical Committee for Standardization 140 “Milk, meat and products of their processing” should play in these processes. Methods. During the research, a systematic approach was used to research factual materials, in particular scientific and scientific-practical literature, regulatory legal acts, regulatory documents and the like, abstract-logical approach to the synthesis of research results and the formulation of conclusions. The results of the study. National standards of Ukraine DSTU is the base of the technical regulation in relation to food products and methods of their control. The above also applies to standardization in the field of milk and meat products, which is within the competence scope of the Technical Committee for Standardization 140 “Milk, meat and products of their processing”. Technical Committee 140 carries out significant work to develop new and update existing national standards in accordance with its area of competence, in particular, it has significant success in harmonizing international and European standards. As of January 15, 2021, according to the classification code 67.100 (Milk and milk products) out of 203 standards of the nationwide force, 103 standards (50.7%) were developed by harmonizing the relevant international standards EN, ISO, etc. According to the classification code 67.120 (Meat, meat products and other animal products) – 202 units, 26 units and 14.1 %, respectively, according to the classification code 67.260 (Installations and equipment for the food industry) – 99 units, 86 units and 86.9%, respectively. The issue of attracting extra-budgetary funds for the harmonization of international standards and the implementation of the entire range of works on standardization is urgent. The issue of proper regulatory support for the production and operation of specialized technological equipment for food and processing industry enterprises is relevant, for which it is advisable to combine the domestic traditions of standardization with the priorities of safety and hygiene of machines, as well as ecology, which are in force in international practice. Scope of research results. The results of the studies performed will be used in the field of technical regulation, in particular, national standardization, of milk and milk products, meat and meat products, determination of safety and quality indicators of the specified food raw materials and finished products made from it, as well as installations and equipment for the food industry.

Top management commitment and lean team members’ prosocial voice behaviour

PurposeTop management commitment (TMC) and prosocial voice behaviour in Lean teams are vital for the successful Lean implementation. This study aims to investigate how TMC influences Lean team members’ prosocial voice behaviour and how such changed voice behaviour affects the outcome of Lean implementations.Design/methodology/approachThe authors have used a qualitative research methodology to examine six dimensions of TMC (communication, involvement, support, empowerment, encouragement and monitoring) in two ready-made garment (RMG) factories in Bangladesh. Operational performance was measured by efficiency, quality, value stream mapping, single-minute exchange dies and 5S scores. Occupational Health and Safety (OHS) was assessed by acceptable head and back positions, machine safety, use of masks and housekeeping.FindingsThe findings reveal that TMC influences Lean team members' voice behaviour positively and, thereby, company's performance. Six dimensions of TMC are all critical for mobilizing prosocial voice, which then improves productivity, OHS and enhancing employee capacity and job satisfaction.Research limitations/implicationsThis research involved two sewing lines in two RMG factories in Bangladesh. Cross-sector and large-scale international quantitative research is also needed.Practical implicationsThis research shows how TMC and Lean problem-solving teams can mobilize employee voice.Originality/valueEmployee voice is a central issue in the implementation of Lean. To the best of the author’s knowledge, for the first time, the authors show how the six dimensions of TMC influence Lean team members’ voice behaviour in the workplace and thereby how prosocial voice affects team performance.