Metal Object Detection in a Wireless High-Power Transfer System Using Phase–Magnitude Variation

Recently, wireless charging technologies for large moving objects, such as electric vehicles and robots, have been actively researched. The power transmitting and receiving coils in most large moving objects are structurally separated by a given distance, which exposes a high output power to the outside world. If a foreign metal object enters the area between these two coils during wireless power transfer, fire hazards or equipment damage may occur. Therefore, we propose a method for detecting foreign metal objects in the gap between the transmitting and receiving coils in a wireless high-power transfer system. A resonant detection coil set is used to exploit the change induced in electrical characteristics when a foreign metal object is inserted. The mutual inductance of the foreign metal object changes the impedance of the detection coil set. We developed a simple circuit to detect both the magnitude and phase change of the voltage signal according to the altered impedance. Additionally, we implemented a prototype of a wireless power transfer system with a detection system to verify that even small foreign metal objects can be detected effectively.

Sensorless metal object detection for wireless power transfer using machine learning

Purpose This study aims to realize a sensorless metal object detection (MOD) using machine learning, to prevent the wireless power transfer (WPT) system from the risks of electric discharge and fire accidents caused by foreign metal objects. Design/methodology/approach The data constructed by analyzing the input impedance using the finite element method are used in machine learning. From the loci of the input impedance of systems, the trained neural network (NN), support vector machine and naive Bayes classifier judge if a metal object exists. Then the proposed method is tested by experiments too. Findings In the test using simulated data, all of the three machine learning methods show high accuracy of over 80% for detecting an aluminum cylinder. And in the experimental verifications, the existence of an aluminum cylinder and empty can are successfully identified by a NN. Originality/value This work provides a new sensorless MOD method for WPT using three machine learning methods. And it shows that NNs obtain high accuracy than the others in both simulated and experimental verifications.

Контроль дефектов в прошедшем через металл импульсном магнитном поле

Experimental dependences U (t) of electric voltage on time t, taken from an induction magnetic head (MG), moving relative to a magnetic carrier (MG) with records of the magnetic fields of defects of an aluminum object, are presented. Contact access to the surface of a metal object, above which there is a layer of air and solid dielectric in an arbitrary proportion and with a total thickness of more than 5 mm, is completely excluded. There is also no access to the rear side of the object, since it is a massive dielectric. The object with MN was exposed to a complex magnetic field pulse with a duration from 1 μs to 200 μs. The studies were carried out in a field that passed through the metal. Raster images of hidden holes with a diameter of 3 mm and 6 mm in layers of aluminum with a thickness of 0.67 mm of samples made up of layers of aluminum of different thickness and separated by layers of dielectric (air) were obtained. The thickness of the metal layers of the samples was 1.96 mm and 2.96 mm. The measurements were carried out in hard-to-reach places of the samples. The algorithm of the developed method was drawn up. The method allows to significantly increase the sensitivity and accuracy of the control of the parameters of defects and to carry out their control of areas of objects where control by other methods is impossible.

Removal of Unusual Foreign Metal Object (Nail) from the Right Ventricle of Human Heart: A Case Report

Migration of foreign bodies (FB) with the blood flow to the heart is a rare, but very alarming condition as it may lead to life-threatening complications and death. Objects that are larger than 5 mm in diameter and/or irregular in shape are recommended for removal from extra- and intracardiac areas to prevent incurable embolization. Surgical extraction of intracardiac objects is a serious surgical challenge associated with difficulties to operate, during the continuous movement of the heart, and identify the exact FB location. Early diagnosis and timely removal of FBs are crucial treatment factors for this rare case resolution. We report a case of accidental migration of a metal FB object (nail) about 1.0*0.3 cm from the right neck area jugular vein to the right ventricle apex in the heart. The FB localization was accurately detected using Bi-plane transesophageal echocardiography (TEE) with a special comet-tail artifact. TEE provided valuable information before surgery, and the nail was successfully removed through open-heart surgical procedures and cardiopulmonary bypass (CPB). Postoperative tests indicated no complications.

The Clinical Features and the Factors Affecting Visual Prognosis in Pediatric Open-Globe Injuries

Purpose: To investigate clinical features and factors affecting visual prognosis after pediatric open-globe injuries.Methods: Children with final logMAR-visual acuity (LVA)>0.70 were determined as poor-vision group (group1, n=108) and those with final LVA≤0.70 as good-vision group (group2, n=115). Analyzes were done. Results: Compared to group1, group2 had better initial and final visions (1.21±0.26 vs 0.60±0.28, p<0.001 for initial-LVA; 1.00±0.32 vs 0.30±0.13, p<0.001 for final-LVA), greater ocular trauma score (OTS) (1.72±0.53 vs 3.73±0.61, p=0.025) and smaller injury size (10.4±3.5 vs 5.8±2.4 mm, p=0.002). Globe rupture (37.0% vs 17.4%, p=0.015) and relative afferent pupillary defect (RAPD) (44.4% vs 17.3%, p=0.037) were higher in group1, while penetrating injury (45.4% vs 72.2%, p=0.044), zone 1 involvement (39.8% vs 65.2%, p=0.038) and metal object injury (29.6% vs 51.3%, p=0.041) were higher in group2. Final LVA (for group1 and group2) was negatively correlated with OTS (r=-0.398, p=0.037; r=-0.369, p=0.040), while positively correlated with injury size (r=0.412, p=0.031; r=0.318, p=0.046) and initial LVA (r=0.335, p=0.043; r=0.402, p=0.034). Conclusion: To our knowledge, this is the first study investigating effects of age, time between trauma and surgery, OTS, injury size, follow-up time and initial vision on final poor and good visions in detail. Low OTS, poor initial vision, globe rupture and RAPD were poor prognosis indicators, while small injury size, penetrating injury, zone 1 involvement and metal object injury were good prognosis indicators. Additionally, in both groups final vision worsened as OTS decreased, injury size increased, and initial vision worsened. These prognostic factors may be useful in managing trauma.

Foreign Body Ingestion Followed by Appendiceal Perforation

Background. Foreign body ingestion is very common among specific groups, especially children. However, appendicitis and perforated appendix caused by a foreign body is rare. Case summary. A 40-year-old female presented with abdominal pain in the right lower quadrant of 10 days duration after accidentally ingesting a drilling bit during a dental procedure. She had right iliac fossa tenderness on physical examination. X-ray showed a pointed long metal object in the right lower quadrant. A contrast-enhanced computed tomography scan of the abdomen revealed a pointed metal object in the pelvis with inconclusive location. Diagnostic laparoscopy showed an inflamed appendix with the tip of the metal object perforating it. Appendectomy was performed. Histopathology showed an inflamed appendix. Conclusion. Foreign bodies that cause appendicitis are rare. However, they may become lodged at any site of the gastrointestinal tract and cause inflammation or perforation. This is a bizarre case of foreign body-induced appendicitis with perforation.