Backup Mode Research Articles

Prospective Evaluation of a Modified Apnea Test in Brain Death Candidates that Does Not Require Disconnection from the Ventilator.

The apnea test (AT) is an important component in the determination of brain death/death by neurologic criteria (BD/DNC) and often entails disconnecting the patient from the ventilator followed by tracheal oxygen insufflation to ensure adequate oxygenation. To rate the test as positive, most international guidelines state that a lack of spontaneous breathing must be demonstrated when the arterial partial pressure of carbon dioxide (PaCO2)≥ 60mm Hg. However, the loss of positive end-expiratory pressure that is associated with disconnection from the ventilator may cause rapid desaturation. This, in turn, can lead to cardiopulmonary instability (especially in patients with pulmonary impairment and diseases such as acute respiratory distress syndrome), putting patients at increased risk. Therefore, this prospective study aimed to investigate whether a modified version of the AT (mAT), in which the patient remains connected to the ventilator, is a safer yet still valid alternative. The mAT was performed in all 140 BD/DNC candidates registered between January 2019 and December 2022: after 10min of preoxygenation, (1) positive end-expiratory pressure was increased by 2mbar (1.5mm Hg), (2) ventilation mode was switched to continuous positive airway pressure, and (3) apnea back-up mode was turned off (flow trigger 10 L/min). The mAT was considered positive when spontaneous breathing did not occur upon PaCO2 increase to ≥ 60mm Hg (baseline 35-45mm Hg). Clinical complications during/after mAT were documented. The mAT was possible in 139/140 patients and had a median duration of 15min (interquartile range 13-19min). Severe complications were not evident. In 51 patients, the post-mAT arterial partial pressure of oxygen (PaO2)was lower than the pre-mAT PaO2, whereas it was the same or higher in 88 cases. In patients with pulmonary impairment, apneic oxygenation during the mAT improved PaO2. In 123 cases, there was a transient drop in blood pressure at the end of or after the mAT, whereas in 12 cases, the mean arterial pressure dropped below 60mm Hg. The mAT is a safe and protective means of identifying patients who no longer have an intact central respiratory drive, which is a critical factor in the diagnosis of BD/DNC. Clinical trial registration DRKS, DRKS00017803, retrospectively registered 23.11.2020, https://drks.de/search/de/trial/DRKS00017803.

Research on topology technology of integrated battery energy storage system with reconfigurable battery and converter

In traditional battery energy storage systems (BESS), batteries are usually connected in a simple series or parallel form, and separate converters and balancing modules are typically used for energy exchange between the battery and external sources, as well as for balancing energy between batteries. This paper proposes an integrated battery energy storage system (IBESS) with reconfigurable batteries and DC/DC converters, resulting in a more compact structure. The IBESS can reconfigure the connection of energy storage batteries based on the battery's status and external demand. The DC/DC converters can operate in different modes such as boost, buck, or buck-boost converters. The IBESS has five working modes: discharging mode, balancing mode, battery discharging and balancing mode, constant current and constant voltage (CCCV) charging mode and backup mode. To verify the feasibility of the proposed energy storage system, a model with four battery modules was built using MATLAB/SIMULINK, and the operation of all working modes was demonstrated. The simulation results verified the system's performance and reliability, demonstrating its flexibility and efficiency in different operating modes.

Using ICG navigation in resection of a horseshoe kidney

BACKGROUND: In this publication, we present a new area of application of indocyanine green (ICG) imaging in pediatric surgery. We used this advanced method to evaluate the resection margins of a functional segment of the horseshoe kidney after intravenous indocyanine green. CLINICAL CASE DESCRIPTION: The article presents a case of treatment of a horseshoe kidney complicated by vesicorenal reflux in the left segment and loss of function of the left segment. Resection of the left half of the horseshoe kidney was performed using fluoroscopic control with intravenous administration of indocyanine green. The surgery was performed using the RUBINA™ endovideosurgical system manufactured by KARL STORZ (Germany). RUBINA™ components offer a variety of ICG in near-infrared fluorescence signal imaging modes. Depending on the surgeon and the application, ICG in near-infrared fluorescence data can be used in different modes: image overlay mode, backup mode, color mapping mode. After confirming the boundaries of the perfused part of the kidney, laparoscopic resection of the functional half was performed at the level of the isthmus. The use of ICG imaging was very important in identifying healthy tissue that stained intensely green 2 minutes after intravenous indocyanine green administration. This margin check verifies the functioning renal parenchyma and allows the correct selection of the nephrectomy margin. The next day after the operation, an ultrasound examination of the renal remnant and perinephric space was performed — the rotation to the right hour of the horseshoe-shaped kidney was good and no accumulation of fluid was detected in the bed of the removed segment. A control ultrasound examination 6 months after the operation showed the preservation of the parenchyma of the right half of the kidney, which indicates the positive effect of the surgical procedure. CONCLUSION: ICG navigation is a promising method for noninvasive assessment of resection margins in patients with horseshoe kidneys.

Development of an innovative model for the inter-integration of the architecture of the intelligent computer environment of critical infrastructure facilities of the railway

The object of research is the processes of intelligent management of the computer environment of data objects of the critical infrastructure of railway transport. When developing an innovative model of deep mutual integration of the architecture of an intelligent computer environment for the management of objects in the power supply system of railway transport, the only urgent task is to solve the problems of efficient and reliable power supply of electricity for train traction to ensure the transportation process. The approaches, mathematical models and methods that became the basis for the creation of an innovative model and a new structure of the management system, the integration of the architecture of the computer environment of data of critical objects of the infrastructure of railway transport, meet the requirements of modernity and the strategy of sustainable development of the transport infrastructure. Management of an intelligent computer environment in the context of the railway power supply system is a complex process that includes the use of various technologies and strategies to optimize the functioning of systems, increase reliability, ensure efficient use of electricity, and ensure the transportation process. The basis of the creation of an intelligent computer environment is the principle of a single informational and synchronous space for the formation of primary information, which is an important concept in the development of intelligent control systems for the power supply system of railway transport. This principle requires that all parameters and data that are collected from different systems of power supply facilities should be combined in a single information space and be available for analysis and management in real time. This principle creates the basis for innovative solutions in the field of railway power supply system management, and the use of the Internet of Things, artificial intelligence, machine learning and deep learning allows the development of systems that meet modern requirements for the efficiency and reliability of energy systems. The use of the approach of deep mutual integration of the architecture of the computer environment is key in the possibility of automating the processes of data collection and analysis, as well as in improving the interaction between the components of the systems of power supply facilities of railway transport, the reliability and efficiency of the system, which makes it more flexible and adaptive to changes in load and working conditions. The research presented in the work can be used in practice in organizations, structural units and at the levels of the management system of critical infrastructure objects in railway transport, transport sector enterprises, which will allow a quick response to an emergency situation and switch to backup modes, ensuring reliability and availability of power supply in conditions of challenges.

Evaluation of NAVA-PAP in premature neonates with apnea of prematurity: minimal backup ventilation and clinically significant events.

Neonates with apnea of prematurity (AOP) clinically deteriorate because continuous positive airway pressure (CPAP) provides inadequate support during apnea. Neurally adjusted ventilatory assist (NAVA) provides proportional ventilator support from the electrical activity of the diaphragm. When the NAVA level is 0 cmH2O/mcV (NAVA-PAP), patients receive CPAP when breathing and backup ventilation when apneic. This study evaluates NAVA-PAP and time spent in backup ventilation. This was a prospective, two-center, observational study of preterm neonates on NAVA-PAP for AOP. Ventilator data were downloaded after 24 h. The number of clinically significant events (CSEs) was collected. A paired t-test was used to perform statistical analysis. The study was conducted on 28 patients with a gestational age of 25 ± 1.8 weeks and a study age of 28 ± 23 days. The number of CSEs was 4 ± 4.39/24 h. The patients were on NAVA-PAP for approximately 90%/min, switched to backup mode 2.5 ± 1.1 times/min, and spent 10.6 ± 7.2% in backup. Preterm neonates on NAVA-PAP had few CSEs with minimal time in backup ventilation.

A novel traveling wave rotary ultrasonic motor with piezoelectric backup function

To fulfill high-reliability requirements for aerospace applications, a novel traveling wave rotary ultrasonic motor with a piezoelectric backup function (Backup motor) is proposed in this paper. The backup function is enabled by the addition of a set of piezoelectric ceramics (PZT). Based on the ultrasonic motor of the CSX-60, a cantilever-tooth backup motor (CTBM) is designed and fabricated. This backup motor can operate in three working modes according to the excitation settings of PZTs, namely normal mode, backup mode, and enhanced mode. The relationships between three working modes’ performances are analyzed by finite element (FE) analysis and prototype tests. The results show that backup mode, as the substitution, can nearly reach normal mode’s performance, while enhanced mode is obviously higher than others. Furthermore, a modified backup motor with straight-tooth (STBM) and different sizes of PZT is designed and tested as a supplement to verify the feasibility of the proposal. In addition, the effect of stress reduction on PZT damage is verified by extreme working experiments. The comparison between the two types of motors indicates that STBM can provide better frictional drive performance. This proposal can provide a new reference for the subsequent reliability study of ultrasonic motors.

Improving the quality of electricity in power supply systems with reservation from diesel generator plants

Subject of research: substantiation of the parameters and application of FACTS-devices of the STATCOM type for improving the quality of electricity in power supply systems with redundancy from diesel generator sets.
 Purpose of research: is to substantiate technical solutions based on semiconductor devices with reactive and active power generation aimed at improving the quality of electricity in remote power supply systems powered in backup mode from diesel generator sets.
 Methods and objects of research: fast Fourier transform, instantaneous power theory, simulation in Matlab Simulink. The object of research is the power supply system with a complete transformer substation 10/0.4 kV and redundancy from diesel generator sets.
 Main results of research: the article presents the features of ensuring the redundancy of the considered power supply system, taking into account the quality of electricity and the rationale for technical solutions to improve it when supplying the household loads of the village in the backup mode from the DGU based on simulation modeling. A spectral analysis of a sharply variable load curve was performed. It is proposed to use a three-level STATCOM at a voltage of 0.4 kV with a supercapacitor storage, which requires less storage energy than a buffer storage, to ensure the quality of electricity when powered by a diesel generator set. The results of the studies carried out testify to the prospects of using STATCOM with a storage device to improve the quality of electricity in low-voltage networks.

Techno-Economic and Environmental Feasibility Study of a Hybrid Photovoltaic Electrification System in Back-up Mode : A Case Report

In developing countries, institutions that have to operate continuously during daylight hours consume relatively large amounts of electrical energy for lighting and air conditioning, leading to high bills. Untimely power cuts lead to a fluctuation in the voltage delivered by the conventional network, which induces the malfunctioning of electrical equipment and the discontinuity of judicial work. The use of photovoltaic solar energy makes it possible, on the one hand, to ensure continuity of service in the event of damage, and on the other hand to stem greenhouse gas emissions through the sustainable nature of this energy. Solar installations also make it possible to maintain the permanent power supply in the event of instability of the electrical network and to correct the voltage variations undergone by the energy equipment. Thus, this (case) study is based on the energy balances evaluated on the buildings of the jurisdiction of the city of Kandi (Benin) to propose effective solutions of electrification according to six (6) technical scenarii. Each component of the back up system has been sized considering technical requirements and an economic and environmental study has been carried out. The results indicate that the integrated scenario 6 of a "back-up" system with a solar fraction of up to 37% (49.5 kWc) seems to be the most suitable conf iguration for the current needs of the Kandi jurisdiction due to the shortest time to return on investment (5.1 years) and the maximum annual savings generated (33,674 USD). The environmental impact study has made it possible to determine the CO2 emissions avoided as well as the contribution of Carbon credits that this jurisdiction would reap has been evaluated at 115.8 tCO2 equivalent, or 10.6 hectares of forest carbon preserved over the life of the project. This configuration is therefore strongly recommended for a sustainable energy mix in the jurisdictions of Benin as well as for administrative or similar sites where electricity consumption is maximum during the day.

Learning‐based multi‐constraint resilient controller placement and assignment insoftware‐defined networksusing covering graph

AbstractThe controller placement problem is one of the most important issues in designing software‐defined networks (SDNs). In this context, one of the major challenges is the problem of multi‐constraint resilient controller placement and assignment (MCRCPA). In this article, considering the main criteria for solving the problem of MCRCPA, we propose a learning‐based approach named Lb‐MCRCPA, which includes a wide range of constraints including resiliency, switch‐to‐controller delay, switch‐to‐controller reliability, inter‐controller delay, and controller capacity in both main and backup modes. In the proposed method, we use an innovative structure called constraint covering graph (CCG) to calculate the reliability and to apply the set of constraints. The CCG is converted into a distributed learning model called irregular cellular learning automata (ICLA). The rules embedded in ICLA, together with the proposed assignment algorithm, can accurately determine the location of controllers. The performance evaluation of the proposed method for about 2600 different cases on more than 20 standard topologies of different sizes, not only proves its superiority over other methods but also proves its near‐optimality compared to the optimal solution.

Improved respiratory parameters with skin-to-skin contact in premature infants with bronchopulmonary dysplasia on NIV-NAVA.

To determine if skin-to-skin contact (SSC) improved respiratory parameters in premature infants with evolving or established bronchopulmonary dysplasia (BPD) on non-invasive neutrally adjusted ventilator assist (NIV-NAVA). Premature infants (<32 weeks gestational age) with BPD on NIV-NAVA were studied. Continuous readings from the Edi catheter (modified nasogastric feeding tube inserted for NAVA ventilation) were compared: pre-SSC (baby in incubator) and end-SSC (just before end of SSC). Sixty-five episodes of SSC were recorded in 12 premature infants with median gestational age at birth of 24.4 (23.1-27.0) weeks and birth weight of 642 (530-960) grams. Peak Edi (uV) in end-SSC 11.5 (2.7-38.7) was significantly lower compared to pre-SSC 15.8 (4.0-36.6), p < 0.001. P mean (cmH2 O) was significantly lower in end-SSC 9.7 (7.3-15.4) compared to pre-SSC 10.3 (7.5-15.5), p=0.008. Respiratory rate (breaths/min) was significantly lower in end-SSC 52.9 (31.1-78.1) compared to pre-SSC 53.4 (35.1-74.1), p=0.031. There was no significant difference in inspired oxygen requirement or time on back-up mode in end-SSC 40.0 (22.1-56.1) and 5.9 (0.0-56.0) compared to pre-SSC 39.0 (26.0-56.1) and 5.1 (0.0-29.3), p=0.556 and p=0.853 respectively. SSC improved respiratory parameters in premature infants with evolving or established BPD on NIV-NAVA.

Deficit mulched drip irrigation improves yield, quality, and water use efficiency of watermelon in a desert oasis region

In the context of global warming, drought is a crucial factor affecting agricultural production, especially for the oasis farming areas of northwestern China, where water resources are extremely scarce. To reveal the response of watermelon water consumption (WC), yield, quality, and water use efficiency (WUE) to water deficit (WD) and to determine the optimal mode of irrigation in the desert oasis areas of Hexi, we applied different WD treatments on a field oasis watermelon in 2020 and 2021. The experiments employed two gradients of light (l) and moderate (m) WD treatments during the seedling (S), vine (V), expansion (E), and maturity (M) stages except for flowering and fruiting (F) stage, with full irrigation during the entire growth period as the control (CK). The results showed that the WC of oasis watermelon at each growth stage was in the order: E > V > S > M > F, in which WC by E stage accounted for 33.15–40.33%. Compared with the CK, WD had an obvious effect on water saving, and WD during the V or E stages inhibited the growth of vine leaves to a certain extent. The Sl treatment (light WD during S stage) had the highest yield and WUE, with significant increases of 5.23–5.38% and 7.10–7.37% (p < 0.05), respectively, in the two years, while the Mm treatment (moderate WD during the M stage) resulted in the best overall nutritional quality of watermelon, with soluble solids, soluble sugars, vitamin C, and soluble protein contents increasing by 11.31%, 33.43%, 24.03%, and 10.31% (p < 0.05), respectively. However, an integrated evaluation that coupled grey relation analysis (GRA) with a technique for determining order preference by its similarity to an ideal solution (TOPSIS) model, considering growth, yield, quality, and efficiency indicators, concluded that the Ml treatment (light WD during the M stage) achieved the highest comprehensive score, followed by the Sl treatment. Therefore, it is recommended that the optimal deficit irrigation mode for oasis watermelon is the Ml treatment, which can balance water savings, yields, and quality improvements, while the Sl treatment can be considered as a backup mode. This study provides theoretical and technical support for achieving efficient water-saving cultivation and scale development of watermelon production in desert oasis areas.

Construction method of ancillary emergency backup service based on battery energy storage system

The power systems with a high proportion of clean energy face both greater uncertainty in power generation and the threat of stability brought by low inertia. After a fault, the rapid drop in power grid frequency, large voltage fluctuations, and insufficient reactive power support can lead to new energy generation units being disconnected from the grid. Fast active and reactive support will play an important role in suppressing fault propagation in low-inertia systems and preventing large-scale power outages. The reserve and frequency regulation market is a necessary means to deal with power grid failure events, but many blackout events occurred due to insufficient reserve capacity and ineffective market transaction mechanisms. As a flexible power regulation resource, BESS (battery energy storage system) has been incorporated into the power ancillary service market planning. In some engineering cases, the frequency regulation ancillary service provided by energy storage has also shown its advantages. However, there is a lack of in-depth research on how to gather BESS to take part in AEBS (ancillary emergency backup services) in the early stage after the failure. Therefore, in view of the dynamic change of power system risks and the different response speed of different backup resources, this paper proposes to establish a segmented combined backup mode to realize the combination of emergency backup at the initial stage of failure and frequency regulation backup during the fault recovery process. A related model of AEBS demand assessment and emergency backup service pricing mechanism is established. And considering the capacity, life loss and opportunity costs of energy storage for AEBS, a LMP (locational marginal price) method is used to calculate the electricity price of AEBS provided by BESS. It has proved the effectiveness by constructing a grid AEBS based on BESS used by the IEEE 30 node system.

Battery autonomy estimation method applied to lead–acid batteries in uninterruptible power supplies

Uninterruptible power supplies (UPSs) provide energy to critical loads in the event of a power outage. During this event, batteries supply the load for a determinate amount of time, which can vary from a few minutes to several hours, depending on the load and battery capacity. The knowledge of this time period is useful to anticipate a system shutdown and to turn on backup generators, if present. With this in mind, this work contributes with a method for predicting battery autonomy time during the operation of UPSs in backup mode. The proposed method is implemented as an algorithm that predicts autonomy. A Thévenin equivalent circuit with variable resistance is used to model the battery. The circuit is employed in learning and predicting battery terminal voltage behavior during discharge. To achieve this, successive curve fittings are made using a Levenberg–Marquardt algorithm. In this way, the predictions of the behavior of terminal voltage and remaining battery autonomy are continuously adjusted. Due to the used strategy, the method has high adaptability, working even with variations in temperature, load steps, and battery aging. The method is developed based on a commercial 1 kW Single-Office/Home Office UPS, that uses a pair of series-connected 12 V/7 Ah lead–acid batteries. The compatibility with different battery banks is demonstrated, as well as the possibility of operation without measuring temperature and current at the batteries, two advantages in economic terms. Experimental results demonstrate the predictions of autonomy over time.

Radiation Hardening Design of Nonvolatile Hybrid Flip-Flop Based on Spin Orbit Torque MTJ and SRAM

Spin orbit torque magnetic tunnel junction (SOT-MTJ) has been widely used for designing nonvolatile flip-flop (NVFF), thanks to its ultrafast switching speed, zero static power consumption, nearly unlimited endurance, etc. However, in the space environment, the write pulse width of the SOT-MTJ is comparable to radiation-induced current duration. Thus, the SOT-MTJ-based NVFF may suffer from soft error induced by the nonvolatile single event upset (NVSEU) in the backup mode. In this paper, we analyze the sensitive nodes in different work modes and propose the radiation hardening circuits for master–slave NVFF (MS-NVFF) to solve the NVSEUs. Based on a physics-based SOT-MTJ compact model and a 40[Formula: see text]nm CMOS design kit, the reliability of MS-NVFF is verified by simulation with 2[Formula: see text]pC charge, which could be reliably integrated into aerospace and avionics electronics in hostile environments.

Cardiac implantable electronic device dysfunctions in patients undergoing radiotherapy: A prospective cohort study.

Increasing numbers of patients with cardiac implantable electronic devices (CIEDs) are undergoing radiotherapy (RT) for cancer. The aim of the study was to prospectively evaluate the incidence, characteristics, and associated factors of CIED dysfunctions related to RT. Between April 2013 and March 2020, all patients with a CIED who underwent ≥1 RT session were enrolled. Patients were monitored according to a systematic protocol, including device interrogation before the first and after each RT session. The primary endpoint was CIED dysfunction, defined as oversensing, total or partial deprogramming, and/or unrecoverable reset. We included a total of 92 CIED RT courses: 77 (83.7%) in patients with a pacemaker and 15 (16.3%) in those with an implantable cardioverter-defibrillator. Overall, 13 dysfunctions (14.1%) were observed during 92 courses (1509 sessions), giving an incidence of 0.9 per 100 sessions. These included nine deprogramming (three total resets to back-up pacing mode and six partial deprogramming that were all successfully reprogrammed), three transient oversensing, and one unrecoverable oversensing requiring CIED and leads replacement. There were no adverse clinical events related to device dysfunction. In multivariable analysis, neutron-producing irradiation (odds ratio [OR], 5.59; 95% confidence interval [CI], 1.09-28.65; p = .039) and cumulative tumor dose (OR, 1.05; 95% CI, 1.01-1.10; p = .007) remained significantly associated with CIED dysfunction. In this prospective study, transient or permanent subclinical CIED dysfunction occurred in 14.1% of RT courses. Our findings emphasize the importance of high-energy beams and neutron-producing irradiation in risk assessment.

Smart Battery Management System Using LiFePO4 Battery for Offline UPS

Power integrated circuits (ICs) have developed solutions for charging systems and power management system for battery powered devices. The main purpose of a battery management system comprises handling the charging cycle to limit the charging time without focusing on the battery. It also monitors the present status of the battery and reports the fault conditions if any malfunction or error occurs. This system is based on a smart LiFePO4 battery for offline UPS, which is used to power up a home AC application with 230VAC/50Hz. The main reason to select the LiFePO4 battery life cycle, it is made up of non-toxic material and this battery is not overheated or catches fire in case of overcharging or overload. In this system, the Arduino UNO microcontroller is used and it takes care of the parameters like battery charging voltage, charging current, and high voltage cutoff at backup mode. It also monitors the battery voltage, battery current, low voltage cutoff, and overload protection at inverter mode.

‘It’s not about having a back-up plan; it’s always being in back-up mode’: Rethinking the relationship between disability and vulnerability to extreme weather

This article presents an empirically driven critique of the predominant theoretical perspective concerning the relationship between disability and vulnerability that continues to underpin much of the scholarship focusing on the human geographies of environmental hazards and disasters, as well as policies and practices of Disaster Risk Reduction. Findings from a study involving semi-structured interviews from six case study sites in the United Kingdom examining responses to prolonged electricity outages during periods of extreme weather demonstrate that the simple equating of disability with vulnerability cannot be sustained. This is because people with disabilities were no less likely than those without disabilities to be able cope and adapt to challenges imposed by extreme weather. Furthermore, in instances where people with disabilities struggled to cope, this can be seen to result from social, physical, and structural constraints, rather than the presence of impairment per se. From this, we argue that the experiences of people with disabilities can be better understood from a relational perspective, which promotes consideration of local relations, interdependencies, and networks within which people with disabilities are embedded, and through which they engage with society and place. We conclude that UK Priority Service Register (PSR) emergency response systems, like other emergency response protocols utilised in other geographic locations and which uncritically equate disability with vulnerability, need to be replaced with an approach that recognises the capabilities and agency of people with disabilities and considers how social and environmental factors interrelate to produce vulnerabilities and enhance capabilities.

Fault zone identification and phase selection for microgrids using decision trees ensemble

Microgrid protection is one of the main challenges that hinders the growth in the number and variety of microgrids being developed. Fault zone identification and phase selection are among protection challenges that existing protection schemes fail to address. This paper proposes a voltage-restrained classifier-based relaying scheme to address the two protection selectivity problems. While fault detection is achieved via an undervoltage function to ensure the sensitivity of the proposed method, Decision Trees (DTs) ensemble functions are used for fault zone identification and phase selection to guarantee the selectivity of the protection scheme. The proposed approach can identify three zones, forward internal, forward external, and reverse external, which (i) facilitates the operation of a relay in primary and remote backup modes, and (ii) avoids nuisance operation under reverse faults, i.e., works as a directional element. The proposed phase selection function can identify all ten types of faults, which enables the isolation of the faulted phase(s) only. The proposed relaying logic does not require any form of communication, instead it relies on readily available sequence component measurements. Transient studies in PSCAD/EMTDC verify the performance of the proposed scheme under various faults and different microgrid operation modes.

Single-Phase Transformerless Line Interactive Uninterruptable Power Supply with Two Independent Control Algorithms

This paper presents the development of two independent control algorithms for an Uninterruptable Power Supply (UPS). It is a mitigation tool to mitigate power interruption. The UPS circuit consists of a bidirectional buck-boost DC-DC converter, a rechargeable battery and a DC-AC/AC-DC converter. The bidirectional DC-DC converter has a function of charging (buck) or discharging (boost) the battery for maintaining DC-link voltage connected to the DC-AC/AC-DC converter. During the normal mode operation, the DC-AC/AC-DC converter supplies voltage to the bidirectional converter by performing AC to DC conversion. Instead, during the backup mode, the converter supplies voltage to the load by performing DC to AC conversion. In this work, a single-loop voltage control algorithm regulates the bidirectional converter. For the DC-AC/AC-DC converter, a multi-loop control algorithm regulates the output current using the inner loop and the output voltage using the outer loop. MATLAB/Simulink simulates the UPS to determine its performance during normal and backup mode operation. From the simulation results, both independent control algorithms can regulate the operation of both converters during both modes of operation. As a result, the UPS system is capable of supplying sinusoidal waveforms with low Total Harmonic Distortion (THD) of output current and output voltage. Both THD values are below 4%.

Usefulness of remote monitoring for the early detection of back-up mode in implantable cardioverter defibrillators

Reversion of an implantable cardioverter defibrillator (ICD) to back-up mode degrades the operating capabilities of the device, puts patients at risk and requires rapid intervention by a manufacturer's technician. To illustrate the usefulness of remote monitoring of ICDs for the early detection of reversion to back-up mode. In our centre, all patients implanted with an ICD, with or without resynchronisation, were offered remote monitoring as soon as the technology became available. Alerts triggered by the remote monitoring system were included prospectively in a register. During a mean follow-up of 5.7±1.3 years, a total of 1594 patients with an ICD (441 with resynchronisation function) followed with remote monitoring were included in the register. Among 15,874 alerts, only 10 were related to a reversion to back-up mode. Among those, seven reversions were caused by radiotherapy, two were fake events and one was caused by magnetic resonance imaging. Except for the two fake events, the eight other patients had an emergency admission for the resetting and reprogramming of their ICD. None of the reversion to back-up mode alerts was followed by a clinical alert (i.e. a shock alert) before the ICD problem was resolved. Reversion to back-up mode is a very rare event, accounting for 0.06% of total alerts; remote monitoring facilitates the early detection of this critical event to resolve the problem faster than the next scheduled follow-up. Remote monitoring can prevent serious damage to the patient and avoids systematic ambulatory control of the ICD after each radiotherapy session.