Types Of Malfunctions Research Articles

Feasibility of Artificial Intelligence Powered Adverse Event Analysis: Using a Large Language Model to Analyze Microwave Ablation Malfunction Data.

Objectives: Determine if a large language model (LLM, GPT-4) can label and consolidate and analyze interventional radiology (IR) microwave ablation device safety event data into meaningful summaries similar to humans. Methods: Microwave ablation safety data from January 1, 2011 to October 31, 2023 were collected and type of failure was categorized by human readers. Using GPT-4 and iterative prompt development, the data were classified. Iterative summarization of the reports was performed using GPT-4 to generate a final summary of the large text corpus. Results: Training (n = 25), validation (n = 639), and test (n = 79) data were split to reflect real-world deployment of an LLM for this task. GPT-4 demonstrated high accuracy in the multiclass classification problem of microwave ablation device data (accuracy [95% CI]: training data 96.0% [79.7, 99.9], validation 86.4% [83.5, 89.0], test 87.3% [78.0, 93.8]). The text content was distilled through GPT-4 and iterative summarization prompts. A final summary was created which reflected the clinically relevant insights from the microwave ablation data relative to human interpretation but had inaccurate event class counts. Conclusion: The LLM emulated the human analysis, suggesting feasibility of using LLMs to process large volumes of IR safety data as a tool for clinicians. It accurately labelled microwave ablation device event data by type of malfunction through few-shot learning. Content distillation was used to analyze a large text corpus (>650 reports) and generate an insightful summary which was like the human interpretation.

INFLUENCE OF PULSE ELECTROMAGNETIC RADIATION ON PERFORMANCE OF ELECTRIC RADIO PRODUCTS

The subject matter is the processes of analysis of the occurrence of reversible and irreversible failures of semiconductor devices under conditions of exposure to electromagnetic radiation. It is shown that the influence of pulsed electromagnetic radiation is accompanied by the emergence of currents in the conductive elements of products and the emergence of their internal fields. The mechanisms for the occurrence of instabilities of natural oscillations of semiconductor components of electrical and radio products, caused by their interaction with flows of charged particles, have been determined. The presence of instabilities of this kind has a significant impact on the spectral (operating) characteristics of electrical radio products. The results obtained in the work make it possible to assess the degree of influence of pulsed electromagnetic radiation on the operating (volt-ampere) characteristics of electrical radio products. The aim is a model of the mechanisms of the emergence and development of instabilities of natural oscillations of semiconductor structures, components of electrical radio products (communication equipment), in the presence of currents and voltages induced by pulsed electromagnetic radiation. The implementation of such a model is due to the possibility of transforming the energy of a flow of charged particles induced by external electromagnetic radiation into the energy of natural vibrations of a semiconductor structure, taking into account the properties of the structure itself (size, concentration of free carriers, permeability). The transformation of the energy of currents induced by electromagnetic radiation into natural vibrations of a semiconductor structure is determined by two effects (transition or Cherenkov radiation) depending on the location of the structure relative to the direction of the currents. The objectives are: the main electromagnetic effects affecting performance of electrical radio products (ERI) under exposure conditions external pulsed radiation and also indicates characteristic changes ERI parameters that determine their functional purpose, which are a consequence of these effects. The methods used are the method of successive approximations over a small parameter, which allows one to determine the spectrum of natural oscillations of a semiconductor device and the mode of their amplification (instability). The following results are obtained. The results of studies characterizing the malfunction of electrical radio products under conditions of exposure to third-party electromagnetic radiation are presented, as well as the main parameters characterizing the electromagnetic resistance of electronic devices to the effects of pulsed currents and voltages. The characteristic types of malfunctions of semiconductor devices (SCD), components of electronic components, in areas of irreversible and reversible failures, as well as the levels of intensities and currents of electric and magnetic fields affecting the SPD, separating the areas of reversible and irreversible failures, are given. Using the energy approach, a physical model of the occurrence of one of the types of reversible failures of the semiconductor element base (the appearance of S-shaped sections of currentvoltage characteristics) has been developed. This physical model makes it possible to determine the criteria for the electromagnetic resistance of a number of semiconductor devices to the effects of external pulsed radiation and also to obtain calculated ratios for assessing the degree of deviation of the operating characteristics of the PPP from the norm. Conclusion. Development of design relationships that determine the modes of amplification (generation) of oscillations of electrical radio products, making it possible to determine the degree of distortion of their current-voltage characteristics (reversible failures) and complete loss of performance (irreversible failures) depending on the parameters of external electromagnetic radiation. The results obtained in the work can be used in the development of amplifiers, generators and frequency converters operating in the millimeter and submillimeter range that are resistant to external electromagnetic radiation. Quantitative estimates of the criterion for reversible failures (instability increments) show that the amount of radiation energy lies within the sensitivity of modern submillimeter radiation receivers and is the cause of failures.

Safety Analysis Using Event Tree Analysis for Multi-Ion Therapy

At the National Institutes for Quantum Science and Technology (QST), a multi-ion therapy using helium, carbon, oxygen, and neon ions has been studied for charged particle therapy with more optimal biological effects. To make multi-ion therapy clinically feasible, a new treatment system was developed to realize the changes of the ion species in each irradiation using the Heavy Ion Medial Accelerator in Chiba (HIMAC). Since radiation therapy is safety-critical, it is necessary to construct a safety system that includes multiple safety barriers in the new treatment system for multi-ion therapy and to perform a safety analysis for the prevention of serious accidents. In this study, we conducted a safety analysis using event tree analysis (ETA) for newly introduced processes in the treatment planning, accelerator, and irradiation system of the multi-ion therapy. ETA is an optimal method to verify multiple safety barriers that are essential for medical safety and to shorten the time for safety analysis by focusing only on the new processes. Through ETA, we clarified the types of malfunctions and human errors that may lead to serious accidents in the new system for multi-ion therapy, and verified whether safety barriers such as interlock systems and human check procedures are sufficient to prevent such malfunctions and human errors. As a result, 6 initial events which may lead to serious accidents were listed in the treatment planning process, 16 initial events were listed in the accelerator system, and 13 initial events were listed in the irradiation system. Among these 35 initial events, 5 cautionary initial events were identified that could lead to serious final events and they had a probability of occurrence higher than 10-4. Meanwhile, the others were all initial events that do not lead to serious accidents, or the initial events that can lead to serious accidents but were considered to have sufficient safety barriers. The safety analysis using ETA successfully identified the system malfunctions and the human errors that can lead to serious accidents, and the multiple safety barriers against them were systematically analyzed. It became clear that the multiple safety barriers were not sufficient for some initial events. We plan to improve the safety barriers for the five cautionary initial events before the start of the clinical trial. Based on these findings, we achieved our objective to conduct a safety analysis for a new treatment system for multi-ion therapy. The safety analysis procedure using ETA proposed by this study will be effective when new systems for radiotherapy are established at QST and other facilities in the future as well.

SIMULATION AND RESEARCH OF SINGLE-PHASE SHORT CIRCUITS IN THE ELECTRICAL NETWORK

The purpose of this work is to model single-phase short circuits in a three-phase electrical network and identify their type by analyzing the angular frequency of the spatial vector. Recently, the saturation of electric networks with powerful non-linear loads, the introduction of conversion equipment and renewable energy sources lead to the need for systematic analysis and research of the quality of electric energy (QEE). One of the factors that significantly affect the operation of electrical equipment is short circuits. In the article, based on the developed model of the formation of QEE distortions, a single-phase short circuit in a three-phase electrical network is investigated by switching it to a single-phase system with two α-β projections and a zero-sequence voltage vector.
 Studies of the influence of the location of the short-circuit point on the voltage in the electrical network have shown that the difference in the distance from the point of damage to the load, type of short-circuit leads to varying degrees of voltage change. Conducted studies have shown that different types of malfunctions and parameters of the electrical network at the point of short circuit cause different disturbances in the electrical voltage in the power supply system. The presence of a short circuit of the same type at different locations leads to different voltage drops and overvoltages. Short-term changes in voltage are the most common distortions of the quality of electrical voltage in electrical networks. The simulation results based on the developed model are consistent with the theory and reliably simulate the change in voltage in the electrical network.
 In the future, the presented model can help in creating a basis for the identification and subsequent control measures of voltage change violations.

Fault classification and detection for photovoltaic plants using machine learning algorithms

<span>Using photovoltaic (PV) energy has increased in recently, due to new laws that aim to reduce the global use of fossil fuels. The efficiency of a PV system relies on many types of malfunctions which may cause significant energy loss during the system’s operation, besides the ecological factors. Consequently, a monitoring system (MS) capable of measuring both the environmental and electrical factors is described in order to gather real-time and historical data and estimate the plant efficiency metrics. Additionally, a recursive linear model for detecting problems in the system is presented, where the input is the irradiance and temperature of the PV module, whereas the output is the power, using the same MS. The achieved fault detection’s accuracy for the 5-kW power plant reached 93.09 percent, based on 16 days and 143 hours of failures under various situations. After detecting a defect, a machine-learning-based algorithm categorizes each defect problem as short circuit, partial shadowing, deterioration, or open-circuit. The performance of the four most prevalent supervised machine learning (ML) approaches for this assignment (Naïve Bias, decision tree, LDA, and KNN) was evaluated according to their results.</span>

БЕЗОПАСНАЯ ЭКСПЛУАТАЦИЯ ВАГОНОВ ПРИ НАЛИЧИИ НЕИСПРАВНОСТЕЙ

A study of various types of malfunctions in railway transport is conducted. Their critical impact on the safety of operation is evaluated. The research is aimed at studying statistical data on appearing failures and malfunctions both on rolling stock and on railway tracks. At high loads on mechanical components, the probability of various defects is high, which requires the most thorough study of the reliability of structural elements. Any deviation can lead to significant breakdowns and cause huge damage, especially for rolling stock for passenger transportation or transportation of dangerous goods. It is also necessary to predict the indicators of reliability and stability of the system to various impacts. In this regard, the study is aimed at evaluating the failures of railway systems and their critical impact on traffic safety. Despite such a great interest in the problems of evaluating and ensuring the safety of railway transport, there is still no unambiguous evaluation of the parameters of railway carriages and the track for the maximum stability coefficient, if exceeded, the train is highly likely to derail.

Универсальный способ превентивной разгрузки судовой электроэнергетической системы

The method of preventive protection for the purposes of safe operation of the ship's electric power system in emergency situations associated with malfunctions of its elements arising during operation is considered. It is shown that existing devices form a command to unload power sources at the moment of overload, when an emergency has already occurred. At the same time, the disconnection of consumer groups occurs with a time delay. For this reason, stopping even one of the working generator sets by protection often leads to deenergization of the vessel due to overload of the remaining operational machines. A notable place in the work is given to the consideration of the method of unloading the network, in which the automatic mode is used to form a command to turn off selected electricity consumers at a time when at least one of the parallel generator sets is already inoperable, but the quality indicators of the generated electrical energy are still within acceptable limits. Within the framework of the proposed approach, the energy state of the entire ship's electric power system is predicted in the event of a decrease in its generating capacity and, if necessary, a team is formed to unload the network. The conditions under which unloading should be carried out are formulated and presented in the form of logical expressions. It is shown that the proposed approach is universal, since it does not depend on the number of generator sets operating in parallel, nor on the number of machines that have failed, nor on the type of malfunctions that have occurred. The functional diagram and description of the original device for preventive unloading of the ship's electric power system, implementing the proposed approach of preventive protection in practice, are presented.

Исследование влияния качества поверхности при изготовлении комбинированных теплообменных элементов технологических реакторов путем склеивания

As is known, the problem of durability is directly related to the technological processes of manufacturing reactor elements, including elements in contact with the internal reactor environment – the reaction zone. Based on this, it is important to develop new, as well as modernize old technologies for manufacturing reactor equipment elements in order to improve their technical and operational characteristics. The technology developed by the authors of this manuscript can act as a technology for manufacturing and assembling elements of reactor equipment. This technology consists of several main stages. One of these stages is the process of roughness formation on the contacting surfaces before gluing them. However, it is necessary to understand that different values of roughness indicators lead to a change in the strength characteristics of adhesive joints. In view of this, the purpose of this study is to determine the strength characteristics of the adhesive joint at various Ra values and adhesive temperature. The article presents an analysis of the most popular thermochemical reactors at the present time, as well as an analysis of the main types of malfunctions leading to the failure of reactor equipment. The developed manufacturing technology of the most wear-prone parts of the reactor (heat pipes, shells) is described. A feature of this technology is the possibility of forming a thermal contact surface on the manufactured parts, which acts as an intensifier of heat exchange, increasing the efficiency of the unit. The practice of using high-strength and high-temperature adhesives is analyzed. Studies have been carried out to determine the strength of adhesive compounds under various conditions. Heat–resistant epoxy adhesives of K-800 and CMK-Vt brands were used as adhesive compositions. The influence of the Ra index in the range from 1 to 6 microns and the influence of temperature in the range from 200 to 600°C on the strength of the adhesive seam is shown.

Improving the Performance Quality Parameters of Routing Protocol for MANET Networks

Routing and mobility in the network is a major in the field of wireless networks MNAET research and contributes greatly to the improvement of the performance of these networks, and achieving the best advantage of the available package which increases the yield and reduces network congestion. The importance of research is that it seeks to provide solutions for routing in MANET networks effectively and with high reliability and that the solutions offered are adapted to changes in the network topology. In addition to the above, it highlights the quest to find a solution to the two types of malfunctions resulting from roaming contracts, which has become necessary to ensure the best performance for this type of network, where you get these malfunctions in the most current routing algorithms.

ИССЛЕДОВАНИЕ НАДЕЖНОСТИ АВТОМОБИЛЕЙ LADA VESTA В ГАРАНТИЙНЫЙ ПЕРИОД ЭКСПЛУАТАЦИИ

Study objective: To minimize the number of malfunctions that occur in Lada Vesta cars that are under warranty. Task: To study reliability using the example of Lada Vesta cars during the warranty period, analyzing the number and types of malfunctions under various operating conditions, as well as learning the advice of the owners of this car. Experimental studies are carried out by the method of observation and statistics on failures. No scientific paper has been devoted to the reliability study of Lada Vesta cars during the warranty period of operation, therefore, the material and methods used in this paper are new and give the opportunity to make recommendations for the manufacturer that will help improve this car and reduce the number of requests from Lada Vesta owners to the dealership during the warranty period. Also, the time for diagnosing the car will be reduced, since the recommendations made will help repair mechanics to find malfunctions faster and more reliably. Accordingly, the number of serviced cars will increase, the time will be reduced for recording other customers who will be satisfied.

Діагностика паливної апаратури, приводу клапанів газорозподілу та форсунок змащення циліндрів сучасних двотактних двигунів

The application of a vibration sensor with an in-cylinder pressure sensor extends the capabilities of internal combustion engines and compressor diagnostics for various types of plants and installations, such as marine diesel engines, refrigeration piston compressors, aircraft engines. The fuel injection equipment malfunctions as valve as valve train system malfunctions could be detected from the experimental indicated diagrams P(V), P(deg) of the engine cylinder operating process as it is known. The main indicators are the following: the shape of the diagram and the parameters of working cycle – the maximum combustion pressure Pmax, the compression pressure Pcomp, mean indicated pressure IMEP, etc. However, it should be considered that different types of malfunctions could have the same reflection on the indicated diagram. For instance, the late fuel injection and the fuel-injection equipment wear could have almost similar effects on the indicated diagram and main diagnostic parameters. Another example is the low compression pressure Pcomp, which could be caused by the cylinder or compression rings wear and by the exhaust valves wrong timing or valve leakage. It should also be mentioned that many types of malfunctions at their early stages are very difficult to detect and clarify based solely on the indicated diagrams analysis. The detection of such malfunctions usually requires the direct measurements of the fuel injection pressure and injector’s needle lift diagrams with accurate valve timing measurements. However, mentioned measurements could be performed under laboratory conditions and are difficult to apply under engine operating conditions. The vibration sensor application could be a reasonable alternative to the direct measurements, as it allows the determination of the injector’s needle lift-off and landing timing, high-pressure fuel pump cut-off and discharge timing, the preheated heavy fuel circulation start/stop timing as well as gas-distribution valves opening and closing timing, the oscillation frequency, and amplitude from the refrigeration system piston compressor valve operation and the cylinder oil injector timing. The vibration sensor has a magnetic basement that allows its easy mounting on the engine parts. All this information could be directly measured during engines and compressor trials by the vibration sensor applied in the advanced diagnostic systems.

Express-diagnostics of rods’ parting-twist off at wells equipped with sucker rod pump

The development of fields that are at a late or final stage of operation is carried out mainly with the use of downhole sucker rod pumps. The most characteristic failures for these installations are rods parting-twist off and malfunctions of pump valves. The methods of eliminating these accidents vary significantly the parting or twist off of the rods involves lifting of the downhole equipment, and the "sticking" of the shut-off valve assembly of the pump is eliminated by "resuscitation" of the downhole equipment (flushing with water, hot oil or solvent). An error in fault identification leads to incorrect planning of work to restore the operability of the downhole equipment and, as a result, to economic losses.
 The cause of malfunctions of the downhole equipment of downhole rod pumping units, as a rule, is determined by analyzing dynamograms. However, in many cases dynamograms do not allow to distinguish the lower twist off of the rods from the malfunction of the valves of the rod pump. In the presented work, a method for the operational determination of the parting or twist off of rods in the well is considered, which consists in creating an electrical circuit "rod string tubing string" and monitoring its integrity. To determine the type of malfunction, the synchronization unit measures the resistance of the system on the dielectric insert via the electromagnetic channel. In case of parting or twist off of the rods, the electrical resistance of the "tubing-pump-rod string" circuit will be much higher (more than 2 ohms) than in the absence of this failure (0...2 ohms).

Determination of lower break-out of the boom on wells equipped plunger pump

Development of fields at a late or final stage of exploitation of the Ural-Volga region is carried out mainly with the use of downhole sucker rod pumping units. The most typical failures for these installations are rods breaks and breaks and pump valve malfunctions. Methods for eliminating these accidents vary significantly: a break or a breakaway of the rods involves lifting the downhole equipment, and the "sticking" of the shut-off element of the pump valve assembly is eliminated by the "resuscitation" of the downhole equipment (flushing with water, hot oil or solvent). An error in recognizing a malfunction leads to incorrect planning of work to restore the operability of downhole equipment, and, as a result, to economic losses.The cause of the downhole equipment malfunctions of the sucker rod pumping units is usually determined by analyzing the dynamogram. However, in many cases dynamometer charts don't distinguish between the bottom flap of the rods and the failure of the sucker rod pump valves. In the article, a method of prompt determination of rod breakage and breakaway in a well is considered, which consists in creating an electrical circuit "rod string - tubing string" and monitoring its integrity. To determine the type of malfunction, the synchronization unit via the electromagnetic channel measures the resistance of the system on the dielectric insert. In case of break-off of rods, the electrical resistance of the "tubing-pump-rod string" circuit will be much higher (more than 2 ohms) than in the absence of this failure (0...2 ohms).

Breaking it down: Review and management of sialendoscopy device malfunctions

PurposeThe present study was aimed at determining common causes of sialendoscopy device malfunctions and identifying a uniform algorithm to manage device failures. Materials and methodsThe FDA Manufacturer and User Facility Device Experience (MAUDE) database was searched for various keywords related to sialendoscopy. Reports between the dates of December 1, 2009 to March 31, 2020 were downloaded for review and included in the study. Variables such as: device, the iatrogenic injury type, and subsequent surgical or medical intervention were collected and details of the malfunction were categorized based on the type of malfunction. Results206 medical device reports were identified; 47 of them which met inclusion criteria (106 were duplicate cases and 53 were irrelevant to the present study). The majority of device malfunctions involved salivary stone extractor baskets (SSEBs), (40/47; 85.1%), followed by malfunctions of balloon dilators (3/47; 6.4%) and sialendoscopes (2/47; 4.3%). Retention of the SSEB was noted in 85% of the SSEB malfunctions. ConclusionsGiven that sialendoscopy is an increasingly popular technique that relies on devices, it is inevitable that device failures will occur for a multitude of reasons. Working to prevent these malfunctions from occurring is the most effective method of harm reduction. Though it is important that sialendoscopists have a discrete, algorithmic approach to manage them when they occur.

Prevention of emergency malfunctions

The article discusses the most common type of malfunctions and the main causes of damage to the electrical cable. A case study of cable failures in the urban network shows that the main cause is the deterioration of insulation, especially due to the fact that the service life of cables reaches 35 years. Therefore, in order to prevent failures and reduce threats, it is necessary to strengthen the monitoring of cable systems and use cables with higher reliability and functionality, for instance, cables made of cross-linked polyethylene.

Методика диагностирования дизельных двигателей автомобильной техники по параметрам акустического сигнала

Objective: Development of a methodology for diagnosing engines of automotive vehicles by the parameters of an acoustic signal. Methods: A mathematical apparatus has been developed for processing acoustic signals of engines, which allows creating an acoustic portrait of the engine under test with high reliability and comparing it with high effi ciency with a reference acoustic portrait of a serviceable engine of the same type. The acoustic signal is removed from the power plant of the car base chassis using a newly created technical diagnostic tool. Results: The developed methodology for diagnosing automotive engines by the parameters of an acoustic signal allows us to signifi cantly increase the level of effi ciency and reliability of troubleshooting in automotive engines without resorting to collapsible diagnostic methods. Practical importance: The developed methodology and new diagnostic equipment make it possible to conclude on the serviceability of the power plant and to give an opinion on further operation or to obtain information on the types of malfunctions in the engine, which will reduce the time for diagnosing automotive equipment in general and speed up the process of identifying malfunctions by a CIP method with the issuance of recommendations for their elimination.

DPM time management analysis for drilling a 200 m deep hole in ground investigation

This paper applies the drilling process monitoring (DPM) method to record and analyse the digital real-time data for the full process of the hydraulic rotary coring project along a 200 m deep drillhole. According to the DPM data, the whole drill project is divided into four periods. The working period (or the full drilling process) consists of a total of 88 roundtrips and costs a total of 76.71 hours. Each roundtrip can be classified into four sections: inserting, drilling, retrieving, and extracting processes. The time distribution of each individual process along the 200 m deep drillhole is obtained by DPM data. As the drillhole depth increases, the time of the total roundtrip, the inserting process, and the retrieving process for one roundtrip increases linearly. The ground strata, the drill machine condition, and the operators’ effectiveness determine the variations in the elapsed time of the drilling process. Furthermore, four types of malfunctions and associated time distribution can be identified by the abnormal DPM data. The factual data and results presented in the paper can quantitatively describe the time distribution of individual drilling processes and provide a digital field management method for drilling information.

Modeling a Proton Exchange Membrane Fuel Cell Stack Cell by Cell: Illustration of a Mechanism for the Propagation of Degradations

This paper is devoted to the modeling of a PEMFC fuel cell stack. First, to justify the hypotheses, original experimental results are presented and show that the gas flow rates feeding a cell in its stack environment highly depend on the thermal management. Then, the generic model of a cell in its stack environment is presented. A two-phase flow model is implemented to calculate the gas flow rates as a function of the pressure drops and considering the amount of liquid water present in both compartments. In this way, the dispatching of the total active gases flow rate between the different cells can therefore be described. Finally, a stack of five cells is numerically assembled by describing the thermal coupling between the cells. Two application examples are conducted. A first one considers a cooling defect and a second one simulates the case where one cell is more degraded than the others. It is shown how these types of malfunction can cause a fuel starvation event. At the end, and for the first time as far as we know, a mechanism of propagation of degradations from cell to cell is proposed. List of symbols SymbolDescriptionUnitSymbolDescriptionUnit Double-layer capacity of the cellF Protonic resistance of the membrane and electrodesΩ water vapor concentrationmol m−3 Thermal resistanceK W−1 Oxygen Concentrationmol m−3 Mass transfer reisstances m−3 Concentration of the saturated vapor at T mol m−3 Water saturation in the channels Specific heat capacity of plateJ/K.kg TemperatureK Effective water vapor diffusion coefficient through the GDLm2 s−1 Cell potentialV Water diffusion coefficient in the membranem2 s−1 Volume of channels m3 Effective oxygen diffusion coefficient through the GDLm2 s−1 Greek Letters Thickness of the GDLm Anodic charge transfer coefficient Standard cell potentialV Cathodic charge transfer coefficient Equivalent weight of the membranekg mol−1 Roughness factor of the electrode Faraday constantC mol−1 Pressure dropPa Current intensityA Electro-osmosis coefficient Exchange current densityA m−2 Water content of the membrane thermal capacity of the MEAJ K−1 Effective thermal conductivity of GDLW mK−1 thermal capacity of the anode/cathode platesJ K−1 Volumetric masskg m−3 Length of the active aream Cathode electrode potentialV Water latent heatkJ mol−1 Upper & lower scripts lower heating value of HydrogenkJ mol−1 in Inlet Molar mass of waterkg mol−1 out Outlet Dry air molar flow ratemol s−1 c Cathode Dry hydrogen molar flow ratemol s−1 a Anode Water vapor molar flow ratemol s−1 ch Channels Water vapor flow rate from electrode to channelsmol s−1 el Electrode Atmospheric pressuremol s−1 m Membrane Total pressure in the anode channelsPa cf Cooling fluid Total pressure in the cathode channelsPa n−1Preceding electrode Universal gas constantJ mol.K−1 n + 1Following electrode Electrical resistance of the cellΩ

Assessment of Radiation-Induced Malfunction in Cardiac Implantable Electronic Devices

BackgroundRadiation therapy (RT) is a standard cancer treatment modality, and an increasing number of patients with cardiac implantable electronic devices (CIEDs) are being referred for RT. The goals of this study were as follows: (i) to determine the incidence of CIED malfunction following RT; (ii) to characterize the various types of malfunctions that occur; and (iii) to identify risk factors associated with CIED malfunction following RT. MethodsA retrospective study of patients with CIEDs who received RT between 2007 and 2018 at 4 Canadian centres (Sunnybrook Health Sciences Centre, Kingston General Hospital, Hamilton Health Sciences Centre, and University of Ottawa Heart Institute) was conducted. Patients underwent CIED interrogation after completion of RT, to assess for late damage to the CIEDs. Data on demographics, devices, and RT were compared for the primary outcome of device malfunction. ResultsOf 1041 patients with CIEDs who received RT, 811 patients with complete data were included. Device malfunctions occurred in 32 of 811 patients (4%). The most common device malfunctions were reduced ventricular/atrial sensing (in 13 of 32 [41%]), an increase in lead threshold (in 9 of 32 [22%]), lead noise (in 5 of 32 [16%]), and electrical reset (in 2 of 32 [6%]). Higher beam energy (≥ 10 MV) was associated with malfunction (P < 0.0001). Radiation dose was not significantly different between the malfunction and non-malfunction groups (58.3 cGy vs 65 cGy, respectively, P = 0.71). ConclusionsAlthough RT-induced CIED malfunctions are rare (occurring in 4% of patients with a CIED who undergo RT), collaborative efforts between radiation oncologists and cardiac rhythm device clinics to optimize CIED monitoring are needed, to detect and manage CIED malfunctions. Malfunctions are more common in patients receiving higher–beam energy (≥10MV)RT.

0887 Diaphragm Pacer Malfunctions Requiring Surgical Repair in CCHS Patients

Abstract Introduction Congenital Central Hypoventilation Syndrome (CCHS) is a genetic disorder that results in the loss of autonomic ventilatory control, and patients require ventilatory support during sleep or both sleep and wakefulness. One method of ventilatory support is diaphragm pacing (DP), where electrodes surgically placed on the phrenic nerve are connected to subcutaneously implanted receivers that communicate with external antennas and transmitter. There are limited data on the frequency of DP malfunctions that require surgical revision. Methods We reviewed the records of 24 CCHS patients ventilated by DP followed at CHLA from 1990-2019. Records were examined for demographics, PHOX2B mutation, pacing duration/day, date and type of malfunctions, age and time since implantation at malfunction occurrence, and repair success rate. Results All 24 patients had thoracoscopic electrode placement. 17/24 (71%) of patients used DP while asleep; 3/24 (13%) during wakefulness only. 4/24 (17%) were not currently using their pacers. 10/24 (42%) patients required at least one surgical intervention (Age at implantation 9 ± 4.6 (SD) years; age at malfunction 12.5 ± 7.4 years). The average time from pacer implantation to malfunction was 3.8 ± 3.5 years. Malfunctions included defective receivers (6), insulation leaks (1), defective electrodes (4), and hardware infection (1). Of 12 unique component repairs, 6/12 (50%) involved changing receivers, 1/12 (8%) involved repairing an insulation leak, 4/12 (33%) involved replacing the electrodes and receivers, and 1/12 (8%) involved hardware extraction. Of the 12 malfunctions, 10 (83%) had successful surgical revision. 2/12 (17%) repairs were not attempted. While awaiting surgical revision, patients were successfully ventilated by unilateral DP. Conclusion Nearly half of CCHS patients on DP experienced malfunctions within 11 years of implantation. The most common DP repair was receiver replacement. Patients who are waiting for repair often successfully ventilate while pacing unilaterally. Support None