Metallic Foreign Object Research Articles

Research on the Detection Method for Feeding Metallic Foreign Objects in Coal Mine Crushers Based on Reflective Pulsed Eddy Current Testing

In response to the difficulties and poor timeliness in detecting feeding metallic foreign objects during high-yield continuous crushing operations in coal mines, this paper proposes a new method for detecting metallic foreign objects, combining pulsed eddy current testing with the Truncated Region Eigenfunction Expansion (TREE) method. This method is suitable for the harsh working conditions in coal mine crushing stations, which include high dust, strong vibration, strong electromagnetic interference, and low temperatures in winter. A model of the eddy current field of feeding metallic foreign objects in the truncated region is established using a coaxial excitation and receiving coil with a Hall sensor. The full-cycle time-domain analytical solution for the induced voltage and magnetic induction intensity of the reflective field under practical square wave signals is obtained. Simulation and experimental results show that the effective time range, peak value, and time to peak of the received voltage and magnetic induction signals can be used to classify and identify the size, thickness, conductivity, and magnetic permeability of feeding metallic foreign objects. Experimental results meet the actual needs for removing feeding metallic foreign objects in coal mine sites. This provides core technical support for the establishment of a predictive fault diagnosis system for crushing equipment.

This is a successful removal of more than 450 pieces of metal objects from a patient’s stomach: a case report

BackgroundIngestion of foreign bodies may be seen unconsciously or intentionally in patients with mental health problems. Most cases pass through the esophagus slowly; however, in some cases, the tumor may be located in narrower areas of the digestive tract that require endoscopic or surgical intervention. This study describes a rare case of successful removal of more than 450 pieces of metal objects from the stomach of a 36-year-old man via ingestion of foreign bodies at Imam Khomeini Hospital in Ahvaz.Case presentationA 36-year-old male patient (Aryan race) presented with complaints of chronic abdominal pain, frequent vomiting, and intolerance to liquids and food. The patient’s companions mentioned a history of gradual ingestion of small metal objects 3 months prior. The patient was conscious and had stable vital signs. In the patient’s X-ray and endoscopy, multiple metal objects inside the patient’s stomach were observed, causing gastric outlet obstruction. The patient underwent gastrostomy surgery, and 452 screws, nuts, keys, stones, and other metal parts weighing 2900 g were removed from the stomach. Five days after the operation, the patient was transferred to the psychiatric service in good general condition and was diagnosed with psychosis, and her condition returned to normal at follow-up.ConclusionSuccessful removal of this foreign body is rare. In chronic abdominal pain, especially in the context of psychiatric disorders, attention should be given to the ingestion of foreign bodies. In swallowing large amounts of sharp and metallic foreign objects, surgical intervention is necessary, especially in cases of obstruction, and saves the patient’s life.

Laparoscopic retrieval of ingested metallic foreign objects in children

Laparoscopic retrieval of ingested metallic foreign objects in children

A Lightweight YOLO Object Detection Algorithm Based on Bidirectional Multi‐Scale Feature Enhancement

AbstractThis paper proposes a lightweight YOLO object detection algorithm based on bidirectional multi‐scale feature enhancement. The problem is that the original YOLOv5 algorithm does not make full use of the relationship between the feature layers, resulting in the loss of target semantic information and a large number of parameters. First, a bidirectional multi‐scale feature‐enhanced weighted fusion backbone network is constructed to extract target features repeatedly. It enhances the fusion ability of shallow detail features and high‐level semantic information to capture richer multi‐scale semantic information. Second, the NCA attention module is built and integrated into the feature fusion network to enhance the critical characteristics of the target region. Finally, the Ghost module is used instead of the convolutional blocks in the original network to lighten the model while reducing the network complexity and training difficulty. Experimental results show that the improved YOLOv5 algorithm achieves 78.8% mAP@0.5 for the PASCAL VOC2012 dataset, which is 1.5% higher than the original algorithm, at 62.5 FPS. The number of parameters is also reduced by 43.6%. The mAP@0.5 on the self‐made metal foreign object dataset reached 98.4%, at 58.8 FPS, which can meet the requirements of end‐device deployment and real‐time detection.

Research on Metal and Living Foreign Object Detection Method for Electric Vehicle Wireless Charging System

In the electric vehicle wireless power transmission system, the high-frequency alternating magnetic field between the transmitter and receiver can have a certain impact on the health of living organisms and may even lead to lesions. In addition, metal foreign objects in an alternating magnetic field can cause their own heating or even cause fires due to the eddy current effect, so foreign object detection is an essential function in the wireless power transmission system of electric vehicles. In order to prevent metals and living organisms from entering the charging area and causing harm to the charging system and living organisms, this paper proposes a method for detecting living organisms and metal foreign objects. Firstly, the equivalent circuits for the detection systems of the living organism foreign objects and metal foreign objects are established, respectively, and the working theory of the detection system is analyzed by deriving equations. Secondly, the comb capacitor simulation model was constructed, and the comb capacitor electrode spacing, wire thickness, and capacitor spacing were designed based on the scale factor γ to explore the effects of the height and bottom area of the living organism’s foreign object on the comb capacitor. We constructed a simulation model of the detection coil and designed the inner diameter D, the number of turns N, and the wire spacing S of the detection coil according to the scale factor β. An arrayed detection coil and comb capacitor combination mode is proposed to realize the function of the simultaneous detection of metal and living organism foreign objects, and a compensation capacitor is introduced to keep the detection system in a resonant state. Lastly, a platform for foreign object detection experiments was set up to detect metal screws and beef chunks compared to the detection area without foreign objects. Metal screws entering the detection area cause a 20% voltage drop in the detection circuit resistor, and beef chunks entering the detection area cause a 30% voltage drop in the detection circuit resistor, so the detection method is effective in detecting both metals and living organisms. The feasibility of the combined mode of arrayed detection coils and comb capacitors was verified.

Novel Sensorless Metal Foreign Object Detection Technique for Wireless Power Transfer Systems Based on Efficiency Analysis

Novel Sensorless Metal Foreign Object Detection Technique for Wireless Power Transfer Systems Based on Efficiency Analysis

Influence Suppression of Metal Foreign Object in Wireless Power Transfer System Using Improved Grey Wolf Optimizer

To address the issue of metal foreign objects interfering with the charging area and causing a significant drop in the Wireless Power Transfer system’s output power, a method to suppress their influence is proposed. First, a circuit model with detection coils is established, the system’s coupling mechanism is analyzed, a mathematical model for output power is derived, and mutual inductance deviation measure is quantified. Next, a finite element simulation model with detection coils is created to simplify the coil design and analyze mutual inductance deviation measure caused by various metal foreign objects. The misalignment of transmitter and receiver coils are considered, and an improved Grey Wolf Optimizer is introduced to optimize compensation topology parameters, targeting output power. Finally, a simulation model and experimental platform are built, and the proposed method is verified through simulation and experimentation. The method can achieve optimal output power in limited iterations while satisfying constraints, confirming its correctness and effectiveness.

Foreign body in rectum- aerosol can

A 53 year-old male with a history of schizophrenia and bipolar disorder presented to the emergency department with worsening abdominal pain. He reported inserting an aerosol can in his anus and was unable to remove the object. The can had been present since midnight the night before. He was concerned that the cap of the can had come loose when he was trying to remove the can from his rectum. On physical exam, his abdomen was distended with a palpable ventral hernia and foreign body. He reported minimal abdominal tenderness with palpation. Abdominal imaging (Figures 1 and 2) demonstrated a large metallic foreign object in the shape of a can in the sigmoid colon with extensive foci of free intraperitoneal air suggestive of bowel perforation. He was immediately taken to the operating room for surgical removal of foreign body. He underwent diagnostic laparoscopy with removal of rectal foreign body, peritoneal lavage, and closure of rectosigmoid perforation. The adhesiolysis portion of the surgical procedure had to be completed using the EndoShears to perform sharp cold adhesiolysis given the aerosol and concern for an intraoperative fire with use of any type of energy or cautery device.

Simulation of Foreign Object Detection Using Passive Inductive Sensors in a Wireless Charging System for Electric Vehicles

During wireless charging of the traction battery of electrically powered vehicles, the active area between the ground and vehicle assemblies must be monitored for inductive power transfer. If metallic foreign objects enter this area, they interact with the magnetic field and can heat up strongly, and thus become a potential source of hazard. To detect such foreign objects, measurements based on passive inductive sensors have already been carried out in advance. However, a large number of factors influence the detectability of metallic foreign objects, such as the characteristics of the magnetic field of the ground assembly coil, the size, shape, position, orientation, and material composition of the foreign objects, or the design of the sensor coils. The related practical testing effort can be reduced if the characteristics of the charging system and the foreign object detection system can be simulated. Therefore, simulation models were developed within the scope of this work and validated with the help of practical measurements. These models were used in the next step to analyze new test arrangements that had not yet been investigated by measurement. In the simulations described here, precision in the range of 1 mV could be achieved. Cumulatively, many influencing factors can be easily investigated, and results can be generated in a largely automated manner and typically in a wider variety than with practical measurements.

Research on Metal Foreign Object Detection Method in Wireless Charging System of Electric Vehicle Based on Array Detection Coil

In order to eliminate the potential safety hazard that arises when metal foreign objects intervene in the wireless charging area of electric vehicles, this paper proposes that a metal foreign object detection method be applied to the wireless charging system of electric vehicles based on the optimal design of the array detection coil. Firstly, the equivalent circuit model of the metal foreign object detection system is established, then the principle of the foreign object detection system is analyzed, and the scale factor β is introduced as the optimization index of the detection coil. Secondly, the change of the scale factor β with the circuit parameters is analyzed and the appropriate circuit parameters are compared and selected. Thirdly, on the basis of the planar square spiral coil, Ansys Maxwell finite element simulation software is used to optimize its structural parameters, combination mode, and resonant circuit, as well as design the anti-series and anti-parallel enhanced detection coil sets with the decoupling and elimination of detection blind spots. Finally, the feasibility of the proposed detection method of metal foreign objects is verified by experiments. The results show that the two array detection coil sets can detect small-sized common metal foreign objects such as paper clips and the proposed double-layer reinforced structure can significantly improve the detection sensitivity of the system.

Effects of Different Materials on Residual Stress Fields of Blade Damaged by Foreign Objects.

Foreign object damage (FOD) is a common mode of failure in high-speed rotating machinery, such as aircraft engines. Therefore, research on FOD is crucial for ensuring blade integrity. FOD induces residual stress on the surface and within the blade, impacting its fatigue strength and service life. Therefore, this paper utilizes material parameters determined by existing experiments, based on the Johnson-Cook (J-C) constitutive model, to numerically simulate impact damage inflicted on specimens, compare and analyze the residual stress distribution of impact pits, and investigate the influence law of foreign object characteristics on blade residual stress. TC4 titanium alloy, 2A12 aluminum alloy, and Q235 steel were selected as foreign objects, and dynamic numerical simulations of the blade impact process were performed to explore the effects of different types of metal foreign objects. This study analyzes the influence of different materials and foreign objects on the residual stress generated by blade impact through numerical simulation, examining the distribution of residual stress in different directions. The findings indicate that the generated residual stress increases with the density of the materials. Additionally, the geometry of the impact notch is also influenced by the density difference between the impact material and the blade. The distribution of the residual stress field reveals that the maximum residual tensile stress in the blade is related to the density ratio, and the residual tensile stress in the axial and circumferential direction is relatively large. It is important to note that a significant residual tensile stress has a detrimental effect on the fatigue strength.

Bronchotomy for metal foreign object removal in pediatric airway

Bronchotomy for metal foreign object removal in pediatric airway

High-Sensitivity Detection Method for Metal Foreign Objects Based on Frequency Optimization in Wireless Electric Vehicles Charging

Metal foreign objects will not only reduce the output power and efficiency of the wireless power transfer (WPT) system, but also will be heated under the eddy current effect. The method based on the detection coil array has been wildly adopted for foreign object detection (FOD), especially in high-power level WPT applications. However, the problems of low sensitivity or misjudgment still exist which leads to a safety hazard. Therefore, high sensitivity of the foreign object-detection method based on the excitation frequency optimization has been proposed in this paper. Based on the impedance change of the detection coil caused by the foreign object coupling, the frequency characteristics of detection sensitivity were analyzed under the conditions of different self-inductance detection coils. Then, the detection coil was designed and its corresponding optimal excitation frequency was selected to achieve the optimal detection effect to eliminate the area of low detection sensitivity. Finally, an FOD experimental prototype was established to verify the proposed frequency optimization strategy. The results show that the sensitivity of the FOD system is up to 97.56%. With the optimal excitation frequency of 6.22 MHz, as for 1-yuan coin in the center position and corner position of the detection coil, the detection sensitivity is 92.89% and 40.16%, respectively, which is 22.13% and 23.89% higher than that of the excitation frequency is 1 MHz. The improvement of detection sensitivity is helpful to detect accurately and eliminate the detection blind area.

Design and Verification of Metal Foreign Body Detection Device for Harvester Based on Eddy Current Effect

Highlights Prevent metal foreign bodies from scratching the intestines of animals and damaging the harvest cutter. Highly integrated design of acquisition circuit. Application of electromagnetic simulation to verify the feasibility of the principle of eddy current effect. Establishment of Support Vector Machine Multi-Classification Algorithm Model. Abstract. Aiming at the problem that the metal foreign bodies mingled in the silage cause damage to the gastrointestinal tract of animals and livestock, as well as irreversible damage to the rotary cutter of the harvester, a metal foreign body detection and sensing device for the harvester feeding drum composed of multiple single coils and signal acquisition units was designed to realize real-time detection and alarm of metal foreign bodies during harvesting. The sensor adopted a monolithic design with high integration of the signal acquisition circuit, which has a strong anti-interference ability. First, the electromagnetic simulation model was established. According to the simulation analysis of the eddy current effect, when the metal foreign object enters the alternating magnetic field, the energy will be lost, and the equivalent impedance of the coil will change accordingly. Then, the existence of the metal foreign body can be determined by detecting the equivalent impedance Rp of the coil. Next, we adopted a support vector machine multi-classification algorithm to train the detection device. In this process, different sizes of metal (copper, aluminum, and iron) were used, which can effectively improve the sensitivity and accuracy of metal foreign body detection. Finally, the sensor was installed on the test stand for multi-scene simulation experiments. The results show that the metal detection sensor can quickly identify the existence of metal by detecting the equivalent impedance Rp based on the eddy current effect; at the same time, the size of this sensor for metal foreign body detection is limited to 0.6 mm in diameter, 12 mm in length, and 100 mm in maximum detecting distance. Keywords: Eddy current effect, Equivalent impedance, Harvester, Metal foreign body, Support vector machine.

Aspects of Foreign Object Detection in a Wireless Charging System for Electric Vehicles Using Passive Inductive Sensors

If the energy transfer for charging the traction battery of an electric vehicle takes place wirelessly and with inductive components, the active area of the charging system must be monitored for safety reasons for the presence or intrusion of metallic objects that do not belong to the charging system. In the past, different concepts for such monitoring have been described. In this paper, passive inductive sensors are used and characterized based on practical measurements. With this type of sensor, the detectability of metallic foreign objects is very closely related to the characteristics of the magnetic field of the charging system. By optimizing the geometry of the sensor coils, the authors show how foreign object detection can be improved even in areas with low excitation of the foreign objects and the sensor coils by the magnetic field. For this purpose, a charging system, with which charging powers of up to 10 kW have been realized in the past, and standardized test objects are used. Furthermore, the thermal behavior of the metallic test objects was documented, which in some cases heated up to about 300 °C and above in a few minutes in the magnetic field of the charging system. The results show the capability of passive inductive sensors to detect metallic foreign objects. Based on the measurements shown here, the next step will be to simulate the charging system and the foreign object detection in order to establish the basis for a virtual development and validation of such systems.

Influence analysis of metal foreign objects on the wireless power transmission system

The wireless power transmission (WPT) system through magnetic field coupling for energy transmission may have foreign objects in the transmission channel in the practical application process, which brings hidden dangers to the WPT system. In this article, a WPT system without and with foreign objects is constructed. The influence of foreign objects on self-inductance and mutual-inductance of coupling coils is studied from the aspects of foreign object height, radius, transmission distance, and coil turns. Then, by constructing the circuit topology of the series structure, the influence of foreign objects on the transmission efficiency and the phase difference between voltage and current of the system is studied, and finally the influence law of metal foreign objects on the performance of the WPT system is summarized.

THE BLEEDING MIGRATION: ESOPHAGEAL INJURY FROM CERVICAL HARDWARE

THE BLEEDING MIGRATION: ESOPHAGEAL INJURY FROM CERVICAL HARDWARE

Optimized design of the detection coils for the metal foreign object detection system applied to wireless power transfer

In order to improve the safety and reliability of electric vehicle wireless charging, foreign object detection is an indispensable auxiliary function. In this paper, the equivalent model of foreign object detection circuit is firstly established, and then the foreign object detection principle based on active detection coil is analyzed from the angle of the circuit and magnetic circuit. Then the optimization scheme of metal foreign object detection coil is proposed through simulation comparison and analysis. The results show that the design proposed in this paper can increase the maximum value of |Bz| to 3.6 mT, effectively improving the accuracy of metal foreign object detection.

Proposal of Wireless Charging Which Enables Magnetic Field Suppression at Foreign Object Location

In the wireless power transmission (WPT) to electric vehicles (EVs) in parking lots, there is a risk of abnormal heat generation due to the absorption of the magnetic field in metallic foreign objects. Accordingly, currently available products are equipped with a function that automatically halts power transmission when a metallic foreign object is detected. However, if possible, continuing power transmission while suppressing the magnetic field absorption may be an another solution. Therefore, this paper proposes a novel function which enables wireless power transmission with high efficiency while suppressing the magnetic field absorption of metallic foreign objects. In this study, it was assumed that a metallic foreign body was present in an arbitrary point in a two-dimensional plane and the power transmission was conducted by the phased array WPT. An algorithm using particle swarm optimization (PSO) to search for the optimal combination of the phase and amplitude of the coil input voltages together with coil arrangements, in terms of both magnetic field suppression and transmission efficiency, is proposed. The simulation was performed with the lower efficiency boundary set as 85% and the load power set as 11 kW, in reference to the SAE J2954 standard. As a result, it was confirmed that the magnetic field suppression effect increased in accordance with the increase in the number of transmission (Tx) coils, thus indicating the effectiveness of the proposed algorithm.

Integrated Solution for Electric Vehicle and Foreign Object Detection in the Application of Dynamic Inductive Power Transfer

One of the challenges with the dynamic inductive power transfer (DIPT) technique is the electric vehicle detection (EVD) that helps the DIPT system to control the power supply of the transmitter. The EVD method applying auxiliary coils is a promising candidate because the flat shape of the auxiliary coils is suitable for the compact design. However, the EVD may fail when the metallic foreign object (MFO) is present. Therefore, the desire emerges in the integration design of the EVD and foreign object detection (FOD). The FOD can ensure the reliability of the EVD as well as the highly efficient operation of the DIPT system without MFOs. In this context, this paper proposes an integrated solution to the EVD and FOD well suited for DIPT systems. The integrated solution utilizes both passive coil sets (PCSs) and active coil sets (ACSs). Additionally, a novel detection resonant circuit (DRC) is proposed to realize EVD and FOD using the same coil sets and to amplify the measurement sensitivity. The operation mechanisms, the detection coil sets architecture, the design of the proposed resonant circuits and the detection procedure are detailed. Finally, a printed circuit board based prototype is built to validate the integrated functionality of the EVD and FOD in a DIPT prototype processing 1 kW output. Experiments considering the practical DIPT application scenarios are conducted, and the proposed detection method is able to achieve advantageously high sensitivity and no blind zone.