Reverse Conditions Research Articles

A Power Routing-Based Fault Detection Strategy for Multi-Terminal VSC-HVDC Grids

Fault detection is one of the most important research topics till today in the field of VSC-HVDC grids protection. In this subject, fast and reliable identification of faults is the most demanding issue, which still requires further study. In this respect, this paper proposes an index for fault detection, which is based on correlation between the powers of DC-link capacitor and the protected line. It is proved by an analytical time-domain transient expression that there is a direct correlation between these two powers under fault conditions. To implement this scheme, the routing of the discharged power of DC-link capacitor into the protected line is the key technique. To do so, the Pearson correlation factor is used in this paper, which efficiently captures the level and direction of the correlation between these two powers. The proposed method benefits from different salient features of very fast fault detection, accurate discrimination of faulted line from healthy lines, covering high-resistance faults, noise immunity, robustness against severe power reversal conditions, robustness against low sampling frequencies, not requiring extra sensor and communication infrastructure, etc. To evaluate the performance of the proposed approach, a complete set of fault scenarios are simulated on a meshed multi-terminal MMC-based VSC-HVDC network.

A different indication of pisphosphonates: Bone marrow edema

Abstract Introduction Bone marrow edema (BME) is an uncommonly diagnosed, reversible condition most often affecting the hip of middle-aged men. BME is characterized clinically by the onset of disabling bone pain, usually at a single skeletal site, generally in the lower limbs and most often the hip. Diagnosis is often delayed. The increased bone turnover and low bone mineral density may indicate a potential role for bisphosphonate therapy in BME. There is some evidence of the successful use of intravenous bisphosphonates in the treatment of BME of the hip. We aimed to present two cases of BME that were successfully treated with bisphosphonates. Clinical Case 1: A 41-year-old male patient presented with left inguinal pain. His past medical history was unremarkable. The visual analog scale (VAS) was 8–9. On physical examination, there was a limited range of motion (ROM) on the left hip. Laboratory results were within normal limits. Non-contrast MRI revealed signal intensity changes consistent with BME in the left femoral head and neck of the femur, which was hypointense in T1W sections and hyperintense in T2W sections. With assisted mobilization, 3 mg IV ibandronic acid, calcium and vitamin D replacement was started. Pain control was achieved one week after bisphosphonate infusion. Complete resolution of bone marrow edema was seen in the MRI taken 2 months later (Figure 1). Bisphosphonate treatment with alendronate was completed for one year. Clinical Case 2: A 59-year-old male patient presented with right hip pain that limits his walking. He was diagnosed with BME and avascular necrosis as a result of clinical and radiological evaluation in the center he applied and he underwent a right femoral core decompression operation. He was evaluated in our clinic due to ongoing pain and limitation of movement 5 months after the operation. On physical examination, there was limited ROM on right hip. All the results of laboratory tests were normal. MRI revealed signal changes consistent with bone marrow edema in the right femoral head and neck of the femur, which was hypointense in T1W sections and hyperintense in T2W sections. With assisted mobilization, 3 mg IV ibandronic acid, calcium and vitamin D replacement was started. Pain control was achieved 10 days after bisphosphonate infusion, and he returned to working life 1 month later. Complete resolution of the BME was observed in MRI performed 10 weeks later. Completion of the bisphosphonate treatment with alendronate for 1 year was planned. Conclusion The hip is the most frequently involved joint, with diffuse BME pattern in the femoral head and intertrochanteric region observed on MRI. BME may be a precursor to avascular necrosis when the diagnosis is delayed or the treatment is not well managed. Therefore, optimal timing of medical intervention is very important. Treatment with bisphosphonates is an effective and safe treatment. Additionally, providing early mobilization may prevent the risk of avascular necrosis and the workforce loss.

Ultrasensitive self-powered heterojunction ultraviolet photodetector of p-GaN nanowires on Si by halide chemical vapour deposition

In this study, we report the fabrication of quasi-aligned p-GaN nanowires (NWs) on n-Si (1 1 1) substrate by halide chemical vapour deposition (HCVD) using MgCl2 precursor and followed by low-energy electron beam irradiation to activate the Mg acceptor doping in GaN NWs. We aimed to attain a comprehensive understanding of p-doping in GaN NWs growth, extensive characterizations and fabrication of UV photodetector (PDs) based on p-GaN NWs/n-Si heterojunction. To realize the efficient UV photodetectors, we measure the current–voltage (I–V) characteristics of heterojunction PDs under dark and illuminated conditions and the I–V curve demonstrates good rectifying behaviours with 0.2 V turn-on voltage. At zero bias, the heterojunction PDs show a reverse photocurrent of 1.27 × 10−6 A with a very low dark current of 2.35 × 10−9 A under 325 nm UV illumination. Besides, the significance of the self-powered operation of UV PDs and the charge transfer mechanism are discussed with the aid of the energy band diagram. The substantial photocurrent increment with varying applied potential leads to narrowing the photo potential in the interface. The excitonic bound states present in p-GaN NWs/n-Si heterojunction is further elucidated. As a result, the heterojunction PDs demonstrate the high responsivity, detectivity, and external quantum efficiency of 134 mA W−1, 3.73 × 1013 Jones, and 51% respectively, at 0.1 V low applied potential under the reverse bias condition. The proposed work provides an archetype for Mg doping in GaN NWs ensembles, which will help to facilitate the heterojunction with n-Si to unleash the potential of self-powered UV PDs.

Numerical Simulation of Flow-Induced Noise in Horizontal Axial Flow Pumps in Forward and Reverse Conditions

This paper investigates the influence of pressure pulsation and flow-induced noise using a two-way dual-purpose pump. The pressure pulsation signal is obtained from the Detached Eddy Simulation (DES) turbulent model calculation as the fan sound source, and the noise sound field distribution in the impeller is calculated. The numerical results show that the external characteristics and pressure pulsation obtained from the simulation correlate well with the experimental values. Under different working conditions, the pressure pulsation decreases with the increase in the flow rate; no evident dominant frequency occurs in the frequency spectrum at a low flow rate, and many spurious frequencies occur. The primary frequency in the runner chamber is the leaf frequency, and that in the nonblade area is the rotating frequency. The sound field distribution of the flow-induced noise has dipole characteristics, and its directivity distribution and sound pressure radiation level can reflect the pressure pulsation characteristics. It is primarily affected by the blade frequency, and the distribution with the flow rate is consistent with the pressure pulsation. Avoiding a low flow and operating in a reasonable flow area can effectively reduce pressure pulsation and flow-induced noise and ensure the stability of unit operation.

An ultralow specific on-resistance bidirectional trench power MOSFET with RESURF stepped oxide

This paper presents an ultralow specific on-resistance (Ron,sp) bidirectional trench power metal-oxide-semiconductor field effect transistor (MOSFET) with RESURF stepped oxide (RSO) for lithium-ion (Li-ion) battery protection circuit application. Compared with the conventional dual die bidirectional switches, the proposed single die structure almost halves the total die area with the same cell pitch. Moreover, the drift region under reverse blocking condition is a 2-D depletion and due to the RSO-assisted depletion effect, the concentration of the drift region under reverse blocking condition can be approximately increased by one order, thus a smaller on-state resistance is obtained. Besides, the parasitic transistor is well suppressed due to the cathode short structure for forwardly and a breakdown margin for reversely blocking conditions, respectively. Consequently, based on the analytical design and simulation, the novel single die bidirectional switch ultimately achieves an ultralow Ron,sp of 1.84 mΩ⋅mm2 with a bidirectional breakdown voltage (VB) of 20 V, which has a better figure of merit (FOM).

Hepatopathy of Mauriac syndrome. The importance of therapeutic adherence.

The Pierre Mauriac syndrome described in the year 1930, is characterized by growth failure, cushingoid appearance, hepatomegaly and hypertransaminasemia, in a patient with chronic uncontrolled DM1. The most common age of presentation is usually in adolescence, although cases have been described in both children and adults. The hallmark of this syndrome is extreme liver enlargement from massive acucumulation of glycogen. The diagnosis of hepatopathy requires high clinical suspicion and the presence of glycogen accumulation must be corroborated with a liver biopsy. The accumulation of glycogen in hepatocytes is partly caused by long periods of hyperglycemia, in which glucose enters the hepatocyte independently of insulin and is converted to glycogen. Mauriac syndrome is currently a rare cause of liver disease, due to improvements in control and treatment of patients with DM1. However, some cases are described in people with complicated social situations or without therapeutic compliance. This is a reversible condition after improvement in glycemic control with adequate insulinization. For this reason, we believe it convenient to suspect this clinical picture in patients with poor glycemic control and symptoms of pain and abdominal distension.

Posterior reversible encephalopathy after normal delivery

Posterior Reversible Encephalopathy Syndrome (PRES) is a clinicoradiological syndrome1 with multifactorial risk factors like preeclampsia and eclampsia. It should be considered in all pregnant and postpartum females having neurological signs and symptoms along with radiological features. Early diagnosis and management is vital in this reversible condition.2

Coupled Inductor Based Voltage Balancing in Dual-Output CLL Resonant Converter for Bipolar DC Distribution System

Bipolar dc distribution systems face imbalances in voltages when unbalanced loads are connected at the outputs. To address imbalances in bipolar voltage levels, dedicated voltage balancers are required. However, they add extra active and/or passive components; including, magnetics, capacitors, etc. This increases the cost, reduces the conversion efficiency, and power density of dual-output converters. Therefore, to tackle the imbalances in output voltages without adding any extra active and/or passive components, this article presents coupled inductor ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CI</i> ) based voltage balancing in dual-output <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CLL</i> resonant converter. The main features of the proposed method are as follows: since <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CI</i> is the result of already present resonant inductors of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CLL</i> tank circuit, therefore, it does not require extra magnetic components to balance the output voltages; with no additional components, it does not increase the magnetic volume, component count, cost, and complexity of the converter; due to the direct coupling, a half of circuit inductances are integrated to achieve the respective resonant inductance of the tank circuit; and it can also avoid complex control schemes applied to voltage balancing. Besides, with the proposed <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CI</i> , the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CLL</i> converter maintains all of its good features including; zero-voltage and zero-current-switching (ZVZCS). The detailed analysis of the proposed <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CI</i> with different load conditions is discussed. Moreover, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> or Type-12 resonant tank circuit is presented to validate ZVZCS operation in the reverse power flow condition. To verify the effectiveness of the proposed <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CI</i> based voltage balancing, a 3.6-kW hardware prototype has been built and tested.

A STUDY OF SPECTRUM OF THE PRECIPITATING FACTORS OF HEPATIC ENCEPHALOPATHY IN CIRRHOSIS PATIENTS

Hepatic Encephalopathy (HE) is a complex, potentially reversible neuropsychiatric condition that occurs due to acute or chronic liver disease1. In managing patients with HE in cirrhosis of the liver it is very important to stage the encephalopathy into four clinical stages and then try to identify and treat the precipitating factors. In the presence of the precipitating factors, the neurological decits are usually completely reversible on their correction and the prognosis is good if the precipitant can be treated2. Results: A total of 54 patients with cirrhosis of the liver suffering from hepatic encephalopathy were studied for different precipitating factors over a period of 15 months. Spontaneous bacterial peritonitis (SBP) (48.14%) is the most common precipitating factor in our study, followed by gastrointestinal bleeding(31.48%), constipation(27.77%), sepsis(24.04%), hyponatremia(20.37%) and hypokalemia(11.11%). Conclusion: Early detection and diagnosis of the precipitating factors of HE help in the focused treatment of this highly fatal condition thereby reducing the mortality in such patients

An Overview of Gingival Diseases in Childhood

The restoration of GH post-treatment for gingivitis or periodontitis is critical, and specific diagnostic criteria are outlined for these conditions. Importantly, even patients with a history of well-managed periodontitis remain at risk for recurrence, necessitating vigilant monitoring and management. Gingivitis, commonly observed in children and teenagers, is a reversible inflammatory condition of the gingival tissue (GT) that does not involve clinical attachment loss (CAL). It serves as a precursor to more severe periodontal diseases characterized by the loss of connective tissue attachment and bone. Controlling gingival inflammation is key to preventing periodontitis and its recurrence. The etiology of childhood gingival diseases is multifactorial, with factors like poor oral hygiene, sugary diets, limited dental care access, and systemic conditions such as diabetes and immunodeficiency playing significant roles. Clinicians must effectively manage gingivitis across all age groups, recognizing the broad categories of gingival diseases: dental plaque biofilm-induced gingivitis and non-dental-plaque-induced gingival diseases.

Evolution of hepatic encephalopathy over time: ecological data from a tertiary referral centre for hepatology.

Few data on hepatic encephalopathy (HE) over time are available, thus our aim was to study its evolution in patients with varying degree of HE on first assessment. Eighty-six patients with cirrhosis (age=58±11 years; males=72) were evaluated 2-10 times for liver transplantation selection purposes, differential diagnosis or treatment optimization. The presence/severity of HE was assessed by clinical and neuropsychiatric indices [ Psychometric Hepatic Encephalopathy Score (PHES) and electroencephalography (EEG)] and the severity of liver disease by the Model for End-Stage Liver Disease (MELD) score. Treatment was instituted/modified after each evaluation. Amongst 23 unimpaired patients, 56/6% remained unimpaired, 35/3% developed covert HE, 9/0% developed overt HE on second/third evaluation. Amongst 32 patients with covert HE, 25/10% became unimpaired, 44/19% remained covert, 31/13% developed overt HE. Finally, amongst 32 patients with overt HE, 19/16% became unimpaired, 25/13 % became covert and 56/25% remained overt. PHES results improved in patients with overt HE and EEG worsened over time (despite remaining normal) in unimpaired patients. In patients with multiple evaluations, HE evolution was manifold and difficult to predict. HE evolution over time is variable and largely dependent on HE history/management. These data support the concept that HE is an essentially reversible condition.

Effectiveness of Pyridostigmine and Pyridoxine in Vinca AlkaloidInduced Cranial Neuropathy – A Case Series

The neurotoxicity of the vinca alkaloids in the form of peripheral neuropathy is well known, however, cranial neuropathy is not widely recognized especially in children. We describe here in three children with malignancies who developed vinca alkaloid induced cranial nerve palsies during treatment which resolved on institution of pyridoxine and pyridostigmine. Vinca-alkaloid-induced cranial nerve palsies represent a potentially dangerous but reversible condition.

Wave-focusing to subsurface targets using a switching time-reversal mirror

The need for wave energy focusing to selected targets embedded within a host is commonly shared among various engineering fields, whether for stimulation and imaging in exploration geophysics, or for contaminant removal in geo-environmental engineering, or even for diagnostic/therapeutic purposes in medicine. In this paper, we are concerned with the feasibility of focusing wave energy to multiple subsurface targets embedded within a semi-infinite heterogeneous elastic host, by exploiting the time-reversibility of the lossless wave equation under adverse conditions for time reversal. Of particular interest for practical applications in geophysics is the need for a switching time-reversing mirror, where recorded Dirichlet data must be time-reversed as Neumann data due to equipment constraints. In the absence of theoretical guarantees, we turn to numerical experiments and report that wave-focusing can be indeed realized, despite various departures from the theoretically ideal time reversal case.

Knowledge, Attitude, and Practice Among Parents of Strabismic Children in Saudi Arabia: A Cross-Sectional Study.

Background Strabismus is a reversible condition that must be identified and treated during the critical period of childhood. Thus, this study aims to evaluate the degree of knowledge, attitude, and practice among parents of strabismic children in Riyadh, Saudi Arabia. Method To this end, a cross-sectional study was conducted from August 2021 to November 2021 with a sample size of 424 parents of children with strabismus seeking ophthalmologic consultants in private and governmental ophthalmology clinics in Riyadh, Saudi Arabia. A self-administered questionnaire was used to collect the data. The questionnaire contains knowledge-related questions about strabismus, beliefs-related questions, questions addressing the barriers parents face regarding strabismus in a child, and sources of information about cross-eye and its management. Data were analysed using the SPSS database version 21 (IBM Corp., Armonk, NY, USA). P-values <0.5 was used for clinical significance. Result We found that most parents know there is a relationship between strabismus and refractive errors (69%) and cross eye can be corrected (55%). Moreover, strabismus causes psychosocial difficulties (55%), low self-esteem, and low school performance. Parents of strabismic children believed that their love for their children is not affected due to crossed eyes (53%) and that strabismic children should not be taken to traditional healers (59%). Barriers faced during the management of strabismus are parents' negligence (76%), fear of surgery (34%), and high cost (29%). Doctors are the most used and preferred source of information among parents of strabismic children. Conclusion This study identifies gaps in knowledge, wrong beliefs in society, and the barriers faced by parents of strabismic children. Thus, raising awareness of the importance of detecting and treating strabismus early, avoiding psychosocial complications, and improving children's quality of life.

Use of Cardiac Magnetic Resonance Imaging to Distinguish Between Acute Myocarditis and Takotsubo Cardiomyopathy

Use of Cardiac Magnetic Resonance Imaging to Distinguish Between Acute Myocarditis and Takotsubo Cardiomyopathy

Pressure fluctuations during the pump power-trip of a low-head pump-turbine with the co-closing of guide vane and ball valve

The pressure fluctuations (PFs) were significantly different for different head pump turbines (PTs). To study the evolutionary mechanisms of PFs inside a low-head PT, the co-closing of the guide vane (GV) and ball valve after a pump power trip was simulated by adopting the one- and three-dimensional coupled approach and dynamic mesh technology. Additionally, the simulation results were validated through comparison with the experimental data. The results suggest that the transient performance and pressure fluctuate severely before the PT passes through the reverse maximum flowrate condition, which causes severe fluctuations in the impeller radial hydraulic thrust (FR). Moreover, the study found that PFs during the transition of low-head PTs also include two new frequency components, fDV caused by the Dean vortices in the spiral casing and the 38–40-fold impeller-rated rotation frequency caused by the periodical interactions between the rotational impeller and the regular high-pressure (HP) regions in the stay/GV, in addition to the frequency components fRSI-S and fRSI-R caused by rotor-stator interactions and fBFV caused by local backflow vortexes close to the impeller inlet. The two new fluctuation frequency components cannot be captured for the middle-head and high-head PTs and primarily influence the axial hydraulic thrust of the impeller (FZ). This finding can provide an important theoretical guide for the design and optimization of low-head PTs.

Challenges, prevention, and countermeasures for social withdrawal (hikikomori) by age group

The term "hikikomori" was recognized by society between 1980 and 2000, when the term "NEET" also appeared and it was regarded as a problem of irresponsible youth. However, accumulation of surveys and research both in Japan and abroad, including those conducted by the Cabinet Office, has revealed that the reasons behind social withdrawal are not only limited to mental illness. There are many people who exhibit withdrawal because they are unable to establish relationships with the community and other people owing to various factors such as social systems, attachment formation, family background, and education. In other words, withdrawal is better described as a "symptom" or "condition" than a disease. Therefore, it is necessary to understand and analyze the diverse backgrounds and needs of individuals with withdrawal and confront them about their state. Currently, many hikikomori people with prolonged withdrawal are now in their 40s and 50s. With their parents' aging, there are cases where people with hikikomori and their families become socially isolated and are unable to make ends meet. It is undeniable that, until now, the society we live in as a whole has little interest in or understanding of hikikomori. In contrast, withdrawal among older adults (tojikomori), which has become a problem in the super-aging society. Tojikomori is defined as "going out less than once a week and not requiring nursing care", which is not equivalent with hikikomori. Owing to the decline in the frequency of going out among the elderly in the recent coronary crisis, the number of pre-frailty in older adults has become a nationwide problem. Thus, both hikikomori and tojikomori are reversible conditions, and can be alleviated by providing necessary support. This paper summarizes the findings of the symposium "Challenges, Prevention, and Countermeasures for Social Withdrawal (Hikikomori) by Age Group" organized by the Committee on Mental Health and Suicide Prevention of the Japanese Society of Public Health at the 79th Annual Meeting of the Japanese Society of Public Health. This article is a compilation of findings that can benefit public health practitioners and researchers.

Weaning from mechanical ventilation: a narrative review

The “weaning” from mechanical ventilation is a process that involves several assessments and steps to aid a patient to reach a “liberation” from the ventilator and allow for breathing autonomy.The process of “weaning” from mechanical ventilation involves several assessments and steps to support a patient in reaching a “liberation” from the ventilator and allow for spontaneous breathing. The weaning process consists of evaluating if the patient is able to breathe with minimal or no ventilation support. This assessment is performed by a diagnostic test named spontaneous breathing trial (SBT), repeated every 24 hours to ensure extubation success. Even though many patients do not meet the eligibility criteria for starting the weaning process, they can still be weaned. For this reason, these criteria should be evaluated in order to assess a possible weaning, rather than adopting absolute standards which have to be met simultaneously. The SBT helps the healthcare professionals to understand the patient’s capacity to sustain physiological breathing once they are extubated (or on spontaneous breathing if a tracheostomy tube is maintained in place). Several patients fail to meet the weaning criteria after less than 20 minutes of the SBT. Therefore, a 30-minute trial is enough to estimate the patient’s capacity to withhold spontaneous breathing. Even if the SBT is currently the gold standard method to conduct the weaning trial, it does not prevent the occurrence of complications after extubation such as upper airways obstruction, increased resistance, loss of airway protective reflexes, cough efficiency, and drainage of tracheobronchial secretions. The preventive use of NIV or High Flow Nasal Cannula is strongly recommended for patients experiencing extubation failure and mechanically ventilated for more than 24 hours after an SBT. A well-performed SBT usually leads to definitive extubation; on the other hand, SBT failure requires a comprehensive investigation on potentially reversible conditions. Prolonged weaning is highly wasteful in terms of time and resources due to the need for a systematic and multidisciplinary approach to successfully face the weaning process.

Controlled Copolymerization of Acrylonitrile and Ethyl 2-cyanoacrylate under Reversible Addition-Fragmentation Chain Transfer Conditions and Thermal Behavior of the Obtained Copolymers

Controlled Copolymerization of Acrylonitrile and Ethyl 2-cyanoacrylate under Reversible Addition-Fragmentation Chain Transfer Conditions and Thermal Behavior of the Obtained Copolymers

Study on Fatigue Characteristics of Axial-Flow Pump Based on Two-Way Fluid–Structure Coupling

When an axial-flow pump is running, there is a very complex flow inside the runner. Based on the two-way fluid–structure coupling method, this paper simulated the forward and reverse operating conditions of an axial-flow pump and calculated the dynamic stress distribution on the blade surface. The stress load spectrum was loaded onto the blade, and fatigue characteristic analysis was carried out to obtain the fatigue life and damage of the blade. This research shows the following: under different working conditions, the dynamic stress is concentrated at the root of the blade, and its amplitude decreases with the increase in the flow rate; at the same time, the change in stress with time shows a periodic change law. Under the working conditions of the turbine, the main frequency is the rotational frequency, and the secondary frequency is composed of multipliers of the rotational frequency, which is obviously affected by the number of blades; the fatigue damage and stress distribution are consistent, and the damage is the most serious at the stress concentration point. The research results of this paper can provide theoretical guidance for the structural design and safe operation of axial-flow pumps.