bluuebunny/crossref_metadata_2025 huggingface dataset:
Energy router interconnection system: A solution for new distribution network architecture toward future carbon neutrality
Authors: Liu Bin , Zhu Bingzhao , Guan Ziyou , Mao Chengxiong , Wang Dan
Published: August 2022

Under the background of carbon neutrality, distribution networks are facing many new challenges, including providing higher power supply reliability and power quality, additional power supply forms, and better information sharing. The traditional distribution network has difficulty coping with these challenges; thus, it is imperative to transform the traditional distribution network architecture. An energy router (ER) is a type of intelligent power electronic device, and has the potential to play a great role in the transformation of the distribution network. This paper proposes the basic architecture of an ER interconnection system (ERIS), where multiple ERs are gathered together to play a stronger role. Aiming for two different stages of the transformation process of the distribution network, two types of ERISs are employed for a single prosumer and multiple prosumers, respectively. The equivalent modelling, main control strategies, and energy management schemes of the two types of ERIS are respectively illustrated. Several ERIS simulation cases are investigated, and the results verify the advantages and satisfactory performance of the ERIS. The proposed ERIS provides an effective solution for building a new distribution network to adapt to the new challenges in a future carbon neutral era.
Second harmonic voltage injection‐based self impedance estimation for effective decoupled droop control in a microgrid
Authors: Malakondaiah Muli , Boddeti Kalyan Kumar , Naidu Bonu Ramesh , Bajpai Prabodh
Published: August 2022

In an islanded microgrid (IMG), droop control effectively shares real and reactive power demands among distributed generators (DGs), thereby regulating the frequency and voltage in high X/R ratio networks. However, there is a strong coupling between the real power voltage and reactive power frequency in medium‐ and low‐voltage microgrids due to the low X/R ratio. For effective droop control, the coupling between the real power voltage and reactive power frequency should be eliminated through decoupling factors. Existing methods in the literature on decoupled droop control do not consider the effect of changing network conditions. This study proposes a decoupling method for improved power sharing among parallel‐operated inverter‐based DGs. Each DG injects a second‐harmonic voltage, based on which a second‐harmonic self‐impedance is calculated at the DG terminal. With certain assumptions, the fundamental self‐impedance is computed and used to determine the decoupling factors. The proposed method was implemented on two test cases and compared with existing droop methods. In comparison, the power‐sharing ratio is close to the actual value of the proposed method. The simulation results clearly demonstrate that the proposed method improves power‐sharing accuracy despite varying the load and network topology.
Improvement of VSG Transient Performance Based on Power Feedforward Decoupling Control
Authors: Liu Andong , Liu Jun , Wu Qiong
Published: August 2022

The suppression of power grid frequency fluctuation, the inhibition of output active power oscillation, and the coupling of active and reactive power at the output of the virtual synchronous generator (VSG) are all investigated in this work. The connection between VSG output active power oscillation inhibition and grid frequency fluctuation suppression is explored, as well as the difficulties of achieving both power oscillation suppression and frequency fluctuation suppression for VSG at the same time. To overcome this problem, a control approach incorporating notch filter power feedforward decoupling and modifying virtual damping coefficient is presented, it is called power feedforward decoupling control (PFDC). The virtual resistance will worsen the P/Q coupling, whereas the virtual inductance will have no effect, according to the results of the P/Q coupling analysis. It can be demonstrated that the suggested solution does not jeopardize P/Q decoupling performance for VSG active power oscillation suppression and grid frequency fluctuation suppression. The understanding of VSG transient performance is deepened by the comprehensive investigation of the three issues. Finally, simulation is used to verify the soundness of the theoretical analysis and proposed strategy, while VSG's transient performance is increased even more.
Robust stability analysis of a novel droop‐based distributed control scheme for islanded operation of DC microgrids
Authors: Mirjafari Mohammadreza , Banejad Mahdi , Molla‐Ahmadian Hamed , Sedehi Ali , Blaabjerg Frede
Published: August 2022

DC microgrid is a high‐efficiency plan for exploiting and controlling distributed generation (DG) resources that can supply local loads in grid‐connected or islanded mode. Conventionally, the droop control method is utilized to attain proper load sharing among the DGs as a decentralized approach in DC microgrids. However, accurate current sharing among DG units with different line resistances is not achievable by the conventional droop control, whereas this method also increases the DC bus voltage deviation. In this paper, a new droop‐based distributed control method is proposed in the secondary control level to overcome the limitations of droop control. To implement the proposed method, only the amount of precalculated virtual voltage drop of DG units is shared with adjacent DGs through a low‐bandwidth communication, and other calculations are local. So, there is no need to define and share new parameters, and get feedback from the DC bus voltage. By employing the proposed method, not only accurate current sharing among the DG units is guaranteed but also DC bus voltage is restored to the nominal value. To ensure the stability of the proposed method, the robust stability and performance of the closed‐loop system are analyzed by structured singular value (µ) under resistive load and communication delay changes. Finally, a DC microgrid is evaluated using MATLAB/Simulink as well as experimental tests to illustrate the validity and efficiency of the proposed method.
Prinzipien der Osteosynthese im Bereich des Gesichtsschädels
Authors: Wilde Frank , Schramm Alexander
Published: August 2022

Während sich die Grundprinzipien der Osteosyntheseverfahren bei der Gesichtsschädelrekonstruktion in den letzten Jahren wenig verändert haben, fand durch Weiterentwicklung der Osteosynthesesysteme und -instrumente sowie durch die Implementierung der computerassistierten Chirurgie einschließlich der Verwendung anatomisch präformierter oder patientenspezifischer Implantate eine entscheidende Weiterentwicklung statt.
Update nephrotisches Syndrom – neue pathophysiologische Konzepte 2022
Authors: Hoxha Elion
Published: August 2022

Was ist neu?

Pathogenese der MGN Die Identifikation der für die Entstehung der MGN verantwortlichen Autoantikörper ermöglicht es, die Diagnose und Therapie an die molekulare Pathogenese der Erkrankung anzupassen. Die zugrunde liegenden Mechanismen der PLA2R1-Antikörper-Entstehung sind noch unklar. Umweltfaktoren wie Luftverschmutzung sowie genetische Faktoren spielen möglicherweise eine wichtige Rolle. Bei der THSD7A-assoziierten MGN können THSD7A-exprimierende Tumore zur Entstehung der THSD7A-Antikörper beitragen.

Klinische Anwendung Eine antigenspezifische Diagnose ist hilfreich, um die anschließende Differenzialdiagnostik der MGN, z. B. eine Tumorsuche, zu individualisieren. PLA2R1-Antikörper sind sehr spezifisch für die Diagnose einer MGN und ermöglichen eine personalisierte Entscheidung für oder gegen eine Nierenbiopsie zur Diagnosesicherung, abhängig von der klinischen und laborchemischen Präsentation der Patienten. Die PLA2R1-Antikörper ermöglichen eine stärkere Anpassung der Therapie an die Pathogenese und der immunologischen Aktivität der MGN. Der PLA2R1-Antikörperspiegel wird sowohl zur Risikoeinteilung als auch für Therapie-Entscheidungen genutzt.

PLA2R1-Antikörperbestimmung PLA2R1-Antikörper können gegen verschiede Bindungsstellen am PLA2R1 gerichtet sein. Aktuell ist im klinischen Alltag die Bestimmung der Gesamt-PLA2R1-Antikörperspiegel entscheidend für die Prognose und Therapieüberwachung.

Neue potenzielle Antigene der MGN In den letzten Jahren wurde eine Vielzahl weiterer potenzieller Antigene bei Patienten mit MGN beschrieben. Ihre pathophysiologische Rolle ist noch nicht geklärt. Je nach beschriebenem Antigen wurden Assoziationen der MGN mit verschiedenen Erkrankungen berichtet.

Pathogenese der MCD und FSGS bleibt ungeklärt. Eine T-Zell-Störung wurde seit Langem als mögliche Ursache angenommen, während in den letzten Jahren auch für B-Zellen und Autoantikörper zunehmend eine pathogenetische Rolle postuliert wird.

Diagnose und Therapie Für die Diagnose einer MCD und FSGS bei Erwachsenen ist die Nierenbiopsie obligat. In der Therapie der primären MCD und FSGS bleibt auch in den neuen KDIGO-Therapie-Empfehlungen die Steroidtherapie die 1. Wahl. In der Zweitlinientherapie werden vor allem Calcineurin-Inhibitoren eingesetzt. Als weitere Therapieoptionen gelten Cyclophosphamid, MMF und Rituximab.
Medikamentenbeschichtete Ballons bei PAVK
Authors: Böhme Tanja , Zeller Thomas
Published: August 2022

Was ist neu?

Paclitaxel-beschichtete Ballons bei femoropoplitealen Läsionen Für die Behandlung femoropoplitealer Gefäßläsionen, bei Verschlusslängen unter 25 cm sowie bei längeren Verschlüssen (wenn kein Venenmaterial vorliegt und/oder das Operationsrisiko hoch ist), wird die endovaskuläre Therapie empfohlen. Um Restenosierungen und Reinterventionen zu vermeiden, wird dabei die Verwendung von medikamentenbeschichteten Ballons empfohlen. Durch die Weiterentwicklung des Ballondesigns kann die Effektivität noch gesteigert werden.

Paclitaxel-beschichtete Ballons bei infrapoplitealen Läsionen Im Stadium der kritischen Extremitäten-Ischämie wird bei infrapoplitealen Gefäßläsionen primär ebenfalls ein endovaskulärer Therapieansatz empfohlen. Aufgrund von inkonsistenten, teilweise widersprüchlichen Ergebnissen verschiedener klinischer Studien, kann der Vorteil medikamentenbeschichteter Ballons bei der Angioplastie infrapoplitealer Arterien bislang nicht ausreichend beurteilt werden.

Sicherheitsaspekt Paclitaxel-beschichteter Ballons Zahlreiche Real-World-Studien und Nachauswertungen prospektiver Studien konnten den in einer früheren Metaanalyse postulierten Zusammenhang einer höheren Mortalität nach Anwendung Paclitaxel-beschichteter Devices weder bestätigen noch einen möglichen Pathomechanismus oder eine Dosis-Wirkungs-Beziehung aufzeigen. Dennoch wurden die Empfehlungen des Bundesinstituts für Arzneimittel und Medizinprodukte (BfArM) zur sorgfältigen Nutzen-Risiko-Abwägung und Aufklärungspflicht noch nicht angepasst.

Sirolimus-beschichtete Ballons Mit dem Zytostatikum Sirolimus steht eine weitere antiproliferativ und zusätzlich antientzündlich wirkende Substanz zur Vermeidung von Restenosierungen bei femoropoplitealen und infrapoplitealen Läsionen zur Verfügung. Die therapeutische Breite von Sirolimus ist zwar größer als die von Paclitaxel, dennoch ist die Gewebeabsorption und -retention von Sirolimus deutlich schwieriger. Erste Ergebnisse aus kleineren Studien, die die Sicherheit und Effektivität Sirolimus-beschichteter Ballons untersuchten, sind vielversprechend, müssen allerdings noch in großen, prospektiven, randomisierten Studien bewiesen werden.
Mitral Annulus Disjunction and Arrhythmic Mitral Valve Prolapse: Emerging Role of Cardiac Magnetic Resonance Imaging in the Workup
Authors: Kulkarni Amol A. , Chudgar Priya D. , Burkule Nitin J. , Kamat Nikhil V.
Published: August 2022

Mitral valve prolapse is a commonly described entity with a highly variable and benign course. However, it is associated with ventricular arrhythmias and sudden cardiac death in a small subset of patients. Recent studies have yielded insight into myocardial mechanics and the causation of ventricular arrhythmias in these groups of patients.

Mitral annular disjunction (MAD) characterized by detachment of mitral annulus from left ventricular myocardium is associated with morphological and functional remodeling of the left ventricular myocardium. Resultant fibrosis acts as a substrate of ventricular arrhythmia and sudden cardiac death.

We present two such cases of arrhythmic mitral valve prolapse associated with MAD. Cardiac magnetic resonance imaging provides excellent morphological information and also helps in the assessment of fibrosis.
Primary Angiosarcoma of the Breast: A Rare Case Report in Postmenopausal Women
Authors: Issar Pratibha , M. Ravindranath , Dewangan Manish , Issar Arnesh Kumar
Published: August 2022

Primary angiosarcoma (PAS) of the breast is a rare malignant tumor arising from endothelial cells lining the blood vessel and accounts for 0.04% of all breast tumors. It occurs predominantly in young patients usually presenting as nonspecific imaging features and is often overlooked and misdiagnosed at radiology and pathology. Angiosarcoma prognosis is generally poor; however, surgery followed by adjuvant chemotherapy and radiotherapy improves the prognosis. We report a rare case of PAS in a 65-year-old postmenopausal woman. She was diagnosed with PAS based on typical clinical, mammography, ultrasound, and magnetic resonance imaging (MRI) features followed by core biopsy of the lesion. Our case had the unique features of enlarged vessels within and surrounding the lesion in mammography, as well as in MRI, which could be very helpful for future diagnosis of this rare PAS in postmenopausal women.
Role of Cardiac MRI Including LGE, T1 and T2 Mapping in the Assessment of Cardiac Involvement in Patients of Nonspecific Aorto-arteritis: A Prospective Study
Authors: Chandrashekhara S H. , Gulati Gurpreet Singh , Sharma Sanjiv , Kumar Sanjeev , Chaudhary Shiv Kumar , Jagia Priya , Seth Sandeep , Gupta Saurabh Kumar , Khan Mahroof
Published: August 2022

Objective Nonspecific aorto-arteritis (NSAA) may involve the myocardium in the form of edema and fibrosis. We conducted this study to investigate role of cardiac MRI including late gadolinium enhancement (LGE), T1 and T2 mapping in the assessment of cardiac involvement in NSAA.

Methods and Materials Over the period between 2016 and 2019, 36 patients with NSAA presenting with uncontrolled hypertension, left ventricular dysfunction, congestive cardiac failure, or tachyarrhythmia were included in the study. We also had 16 voluntary control patients for providing normal T1 and T2 mapping values.

Results The average age of patients was 27.1 years and the majority were females. MRI is more sensitive than echocardiography in the detection of LV dysfunction and RWMA. Out of 36 patients, 10 (27.8%) had LGE. The most common pattern of midmyocardial enhancement was present in 5 out of 10 patients. Five (13.8%) patients show mid-myocardial enhancement, followed by epicardial enhancement, which was seen in four (11.11%) patients. The values of post-gad T1 mapping values were significantly lower than pre-gad T1 mapping values. At a cut-off global native T1 mapping value of 1019 milliseconds had the sensitivity of 83.3% and specificity of 81.2% in detecting an abnormal T1 map. No significant association of MRI contrast enhancement with elevated ESR and CRP levels. There was no significant relation of myocardial T2 mapping values between NSAA and control groups.

Conclusion Quantitative tissue characterization in the myocardium with native T1 mapping values help in the detection of cardiac involvement in patients with NSAA. T1 mapping may provide incremental value in the assessment of myocardial involvement in NSAA in addition to LGE imaging.
Neonatal Hypoxic–Ischemic Encephalopathy: Perspectives of Neuroprotective and Neuroregenerative Treatments
Authors: Pedroza-García Karina A. , Calderón-Vallejo Denisse , Quintanar J. Luis
Published: August 2022

Hypoxic–ischemic encephalopathy (HIE) is a serious condition that could have deleterious neurological outcomes, such as cerebral palsy, neuromotor disability, developmental disability, epilepsy, and sensitive or cognitive problems, and increase the risk of death in severe cases. Once HIE occurs, molecular cascades are triggered favoring the oxidative stress, excitotoxicity, and inflammation damage that promote cell death via apoptosis or necrosis. Currently, the therapeutic hypothermia is the standard of care in HIE; however, it has a small window of action and only can be used in children of more than 36 gestational weeks; for this reason, it is very important to develop new therapies to prevent the progression of the hypoxic–ischemic injury or to develop neuroregenerative therapies in severe HIE cases. The objective of this revision is to describe the emerging treatments for HIE, either preventing cell death for oxidative stress, excitotoxicity, or exacerbated inflammation, as well as describing a new therapeutic approach for neuroregeneration, such as mesenchymal stem cells, brain-derived neurotrophic factor, and gonadotropin realizing hormone agonists.
Congenital Nasal Pyriform Aperture Stenosis: Same CT Dimensions, Varied Scenarios
Authors: Naina Picardo , Dahiya Vijeyta , Irodi Aparna , Varghese Ajoy Mathew
Published: August 2022

Congenital nasal pyriform aperture stenosis (CNPAS) is a rare cause of neonatal respiratory distress. We report a case series of four infants with similar radiological dimensions but while two needed surgery, two could be managed conservatively. The clinical presentation of the child and the response to conservative treatment, rather than the radiological dimensions were the main predictors for surgical intervention.
Neurological and Neuroradiological Patterns with COVID-19 Infection in Children: A Single Institutional Study
Authors: Rastogi Sanchi , Gala Foram , Kulkarni Shilpa , Gavali Vrushabh
Published: August 2022

Background Varied neurological manifestations in pediatric patients with coronavirus disease 2019 (COVID-19) have been increasingly reported from all across the world in the scientific literature.

Objective We aimed to evaluate pediatric cases with neurological symptoms and neuroimaging findings with COVID-19 infection in our hospital.

Materials and Methods Children from 0 to 12 years with laboratory evidence of COVID-19 infection and acute neurological manifestations within 3 months, who have undergone magnetic resonance imaging (MRI) were included in the study. We categorized them based on neurological findings into four groups: acute encephalitis syndrome (AES), acute flaccid paralysis (AFP), cerebrovascular event/stroke, and miscellaneous consisting of acute seizures without encephalopathy.

Results A total of 19 children with neurological manifestations related to COVID-19 infection were included in the study. AES was the most common neurological syndrome seen in 47.36%, followed by AFP in 26.31% and cardiovascular event/stroke in 21.05%. Seizure was the most common neurological symptoms in 62.15%, followed by encephalopathy in 42.10% and AFP in 26.31%. On neuroimaging, pattern observed were immune-mediated cauda equina nerve roots enhancement in 26.31% or acute disseminated encephalitis in 5.26%, small acute infarcts, hippocampal, and bilateral thalamic signal changes seen in 21.05% each, microhemorrhages and leukoencephalopathy in 15.78%, and coinfection in 5.26%.

Conclusion In our study, seizures and encephalopathy were the most common neurological symptoms with COVID-19 infection. Postinfectious immune-mediated cauda equina nerve root enhancement or acute demyelinating encephalomyelitis–like brain imaging, followed by small acute infarcts and hippocampal/thalamic signal changes were most common imaging patterns. We found overlapping neurological and MRI patterns in many children, suggesting that various pathophysiological mechanisms act individually or synergistically.
Diagnostic Performance of Acoustic Radiation Force Impulse Imaging in Evaluating Liver Fibrosis in Patients with Chronic Hepatitis B Infection: A Cross-Sectional Study
Authors: Bui Hoang Huu , Vo Van Huy , Nguyen Chuong Dinh , Phan Sang The , Quach Phong Tien , Nguyen Dung Bich
Published: August 2022

Background Acoustic radiation force impulse point shear wave elastography (ARFI-pSWE), measuring shear-wave velocity (SWV), has been utilized to examine the liver stiffness caused by different etiologies. However, information on its reliability in staging liver fibrosis in chronic hepatitis B (CHB) patients is scarce.

Purpose The aim of the study is to examine the diagnostic performance of ARFI-pSWE and determine the optimal SWV cut-off values to predict significant fibrosis (F ≥2) and cirrhosis (F4) in CHB patients.

Material and Methods All 114 adult CHB patients visiting the University Medical Center, Ho Chi Minh City, Vietnam between February 2019 and March 2021 underwent liver stiffness measurement using ARFI-pSWE and FibroScan. SWV results were tested against FibroScan for sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). The area under the receiver operating characteristic (AUROC) curve was used to identify the optimal SWV cut-off values.

Results There was a strong agreement between ARFI-pSWE and FibroScan (r = 0.92, p <0.001). The optimal SWV cut-off value for detecting significant fibrosis was 1.37 m/s with an AUROC of 0.975, sensitivity of 83.3%, specificity of 100%, PPV of 100%, and NPV of 81%. The optimal cut-off value for predicting cirrhosis was 1.70 m/s with an AUROC of 0.986, sensitivity of 97%, specificity of 93%, PPV of 95%, and NPV of 96%.

Conclusion ARFI-pSWE could be an effective technique for evaluating liver fibrosis in CHB patients. SWV cut-off values of 1.37 and 1.70 m/s could be used to diagnose significant fibrosis and cirrhosis, respectively.
A Rare Case of Primary Hyperparathyroidism Presenting as a C2 Brown Tumor-Plain Radiography Has yet again Proved Indispensable in Clinching the Diagnosis
Authors: Panwar Jyoti , Bhat Tameem A. , Ballabh Saket , Abraham Deepak , Jebasingh Felix K.
Published: August 2022

A brown tumor is one of the manifestations of hyperparathyroidism. It is a rare type of bone lesion that most often occurs in mandible, ribs, and large bones. Spinal involvement is extremely rare. We report an unusual case of a brown tumor of the axis vertebra in a 33-year-old male who presented to the orthopaedic clinic with posttraumatic C2 vertebra fracture and myelopathy. To plan further fixation and stabilization of C2 fracture, the patient underwent a plain radiograph and magnetic resonance imaging (MRI) of the cervical spine. The available routine chest radiograph at the time of MRI reporting clinched the diagnosis of primary hyperparathyroidism with a brown tumor of the axis vertebra. Thus, familiarity with subtle radiographic findings of this condition not only led to early diagnosis and appropriate treatment but also avoided unnecessary C2 biopsy and hardware fixation.
Perturbation influence of a parity-time optical resonator pair
Authors: Zhou Peiji , Wu Yulin , Wan Weishi , Weng Binbin , Zou Yi
Published: August 2022

In this article, we study the perturbation influence on a parity-time (PT) optical resonator pair. Critical characteristics of this type of device, including the sensitivity, dynamic range, and robustness, are formulated and discussed systematically. Through the study of three operational phase regimes, the exceptional point (EP), the PT-symmetry, and symmetric broken phases, we find that the optimal range of the PT resonator pair prefers to be at the PT-broken phase regime near the EP state, considering both the robustness and sensitivity factors. Furthermore, we also find that the device’s dynamic range is proportional to the temporal coupling coefficient κ and gain/loss coefficient γ, which means increasing the coupling and gain/loss coefficients will enable a broader dynamic response. Additionally, we further suggest that: (1) to enhance the sensitivity, γ should be no less than 0.94κ; (2) to achieve a large gain factor of a ⩾ 2, γ must satisfy 0.995κ ⩽ γ ⩽ 1.06κ; and (3) to obtain a larger dynamic range, γ needs to be closer to κ. In particular, for γ = κ, i.e., the EP case, the largest dynamic range of ɛ ⩽ 0.24κ is obtained.
Myocardial infarction from a tissue engineering and regenerative medicine point of view: A comprehensive review on models and treatments
Authors: Basara Gozde , Bahcecioglu Gokhan , Ozcebe S. Gulberk , Ellis Bradley W , Ronan George , Zorlutuna Pinar
Published: August 2022

In the modern world, myocardial infarction is one of the most common cardiovascular diseases, which are responsible for around 18 million deaths every year or almost 32% of all deaths. Due to the detrimental effects of COVID-19 on the cardiovascular system, this rate is expected to increase in the coming years. Although there has been some progress in myocardial infarction treatment, translating pre-clinical findings to the clinic remains a major challenge. One reason for this is the lack of reliable and human representative healthy and fibrotic cardiac tissue models that can be used to understand the fundamentals of ischemic/reperfusion injury caused by myocardial infarction and to test new drugs and therapeutic strategies. In this review, we first present an overview of the anatomy of the heart and the pathophysiology of myocardial infarction, and then discuss the recent developments on pre-clinical infarct models, focusing mainly on the engineered three-dimensional cardiac ischemic/reperfusion injury and fibrosis models developed using different engineering methods such as organoids, microfluidic devices, and bioprinted constructs. We also present the benefits and limitations of emerging and promising regenerative therapy treatments for myocardial infarction such as cell therapies, extracellular vesicles, and cardiac patches. This review aims to overview recent advances in three-dimensional engineered infarct models and current regenerative therapeutic options, which can be used as a guide for developing new models and treatment strategies.
Theoretical and experimental studies of multi-port RF power feeding in rod-type radio frequency quadrupole (RFQ) linac
Authors: Pandey H. K. , Dechoudhury S. , Naik V.
Published: August 2022

An analytical and experimental study of multi-port RF power feeding in a four rod-type radio frequency quadrupole (RFQ) has been discussed. First, we have derived generalized relations for multi-coupler power feeding based on S-parameters for n balanced couplers. Using simulation and measurements on a prototype, the optimum position and orientation of two and four couplers in an 80 MHz extended vane rod type RFQ have been determined. A low power RF test has been carried out to show the phase and power balancing using S parameter analysis for two and four mock-up couplers for the RFQ. As a corroborative study, the vane tip voltage measured with a vector voltmeter showed that voltage corresponding to power fed through a single coupler (β = 1) agrees with the value when the same power is fed using two or four couplers.
Elasticity can affect droplet coalescence
Authors: Varma Sarath Chandra , Dasgupta Debayan , Kumar Aloke
Published: August 2022

Coalescence of two droplets on a solid substrate is an interfacial phenomenon that imposes the challenges of capturing the complex contact line motion and energy interaction between the solid–liquid interface. Recent investigations on the coalescence of polymeric droplets on a solid substrate have reported strong disagreements; the heart of the issue is whether coalescence of polymeric drops is similar to that of Newtonian fluid and is independent of molecular relaxation, or whether the role of entanglement of polymeric chains leads to a transition kinetics different from that of Newtonian fluid. Via this article, we resolve the disagreements through a discussion on the effects of merging method on the dominant forces governing the coalescence process, i.e., inertia, dissipation, and relaxation. In this regard, two methods of merging have been identified, namely, the droplet spreading method and the volume filling method. Our study unveils that the coalescence dynamics of polymeric drops is not universal and, in fact, is contingent of the method by which the coalescence is triggered. Additionally, we demonstrate the spatial features of the bridge at different time instants by a similarity analysis. We also theoretically obtain a universal bridge profile by employing the similarity parameter in a modified thin film lubrication equation for polymeric fluids.
Effect of tab length on supersonic jet mixing
Authors: Rathakrishnan Ethirajan
Published: August 2022

An experimental investigation has been carried out to assess the efficiency of rectangular tabs of 5% blockage with three different aspect ratios of 1, 1.5, and 2, in promoting the mixing of a Mach 1.73 axisymmetric free jet, in the presence of adverse and favorable pressure gradient, by varying the operating nozzle pressure ratio (NPR) from 4 to 8, in steps of 1, covering all the three levels of expansion, namely, the over-, correct-, and underexpaned states at the nozzle exit. For NPR 4, the Mach 1.73 jet is overexpanded with an adverse pressure gradient of about 23%. At NPR 5, the nozzle is almost correctly expanded with an adverse pressure gradient of only about 3%. At NPRs 6, 7, and 8, the nozzle is underexpanded with favorable pressure gradients of 16%, 35%, and 55%, respectively. It is found that as high as about 88% reduction in the core length is achieved by the tab with an aspect ratio of 1.5 at NPR 7. However, the reduction caused by tabs with aspect ratios of 1 and 2 is only 73.3% and 42.3%, respectively. It is to be noted that though the mixing promotion caused by the tab with an aspect ratio of 1.5, at NPR 7, leads to the core length reduction to the tune of about 88%, it is at the cost of momentum thrust loss of about 5% and the drag caused by the tabs. It is also found that except at NPR 4, the mixing caused by the tab with an aspect ratio of 1.5 is better than tabs with aspect ratios of 1 and 2. The shadowgraph pictures for the uncontrolled and controlled jets demonstrate the effectiveness of the tabs in weakening the waves present in the jet core.
Electric double layer of spherical pH-responsive polyelectrolyte brushes in an electrolyte solution: A strong stretching theory accounting for excluded volume interaction and mass action law
Authors: Sin Jun-Sik , Choe Il-Chon , Im Chol-Song
Published: August 2022

In this paper, we study the electrostatics of pH-responsive polyelectrolyte-grafted spherical particles by using a strong stretching theory that takes into account the excluded volume interaction and the density of chargeable sites on the polyelectrolyte molecules. Based on free energy formalism, we obtain self-consistent field equations for determining the structure and electrostatics of spherical polyelectrolyte brushes. First, we find that the smaller the radius of the inner core, the longer the height of the polyelectrolyte brush. Then, we also prove that an increase in the excluded volume interaction yields a swelling of the polyelectrolyte brush height. In addition, we demonstrate how the effect of pH, bulk ionic concentration, and lateral separation between adjacent polyelectrolyte chains on the electrostatic properties of a spherical polyelectrolyte brush is affected by the radius of the inner core, the excluded volume interaction, and the chargeable site density.
Sand and fire: applying the sandpile model of self-organised criticality to wildfire mitigation
Authors: Gang Joshua E. , Jia Wanqi , Herniter Ira A.
Published: August 2022

Background Prescribed burns have been increasingly utilised in forest management in the past few decades. However, their effectiveness in reducing the risk of destructive wildfires has been debated. The sandpile model of self-organised criticality, first proposed to model natural hazards, has been recently applied to wildfire research for describing a negative linear relationship between the logarithm of fire size, in area burned, and the logarithm of fire incidence number of that size. Aims We demonstrate the applicability of the sandpile model to an understanding of wildfire incidence and its trend with interested factors, such as prescribed burns. Methods We leverage the sandpile model to perform a series of simulations, along with comparisons to historical wildfire data in three American states: Florida, California, and Georgia. Key results Both simulated and historical data indicate that increased prescribed burning is associated with lowered incidence of large wildfires. Conclusions Our study justifies the application of the sandpile model to wildfire research and establishes a novel method for facilitating the investigation of potential risk factors of wildfires. Implications The sandpile model may be utilised for the development of optimal strategies for prescribed burning. An R-script for sandpile model simulation is available for further wildfire investigation.
Review in situ transmission electron microscope with machine learning
Authors: Cheng Zhiheng , Wang Chaolun , Wu Xing , Chu Junhao
Published: August 2022

Advanced electronic materials are the fundamental building blocks of integrated circuits (ICs). The microscale properties of electronic materials (e.g., crystal structures, defects, and chemical properties) can have a considerable impact on the performance of ICs. Comprehensive characterization and analysis of the material in real time with high-spatial resolution are indispensable. In situ transmission electron microscope (TEM) with atomic resolution and external field can be applied as a physical simulation platform to study the evolution of electronic material in working conditions. The high-speed camera of the in situ TEM generates a high frame rate video, resulting in a large dataset that is beyond the data processing ability of researchers using the traditional method. To overcome this challenge, many works on automated TEM analysis by using machine-learning algorithm have been proposed. In this review, we introduce the technical evolution of TEM data acquisition, including analysis, and we summarize the application of machine learning to TEM data analysis in the aspects of morphology, defect, structure, and spectra. Some of the challenges of automated TEM analysis are given in the conclusion.
Influence of epitaxial layer structure and cell structure on electrical performance of 6.5 kV SiC MOSFET
Authors: Tian Lixin , Du Zechen , Liu Rui , Niu Xiping , Zhang Wenting , An Yunlai , Shen Zhanwei , Yang Fei , Wei Xiaoguang
Published: August 2022

Silicon carbide (SiC) material features a wide bandgap and high critical breakdown field intensity. It also plays an important role in the high efficiency and miniaturization of power electronic equipment. It is an ideal choice for new power electronic devices, especially in smart grids and high-speed trains. In the medium and high voltage fields, SiC devices with a blocking voltage of more than 6.5 kV will have a wide range of applications. In this paper, we study the influence of epitaxial material properties on the static characteristics of 6.5 kV SiC MOSFET. 6.5 kV SiC MOSFETs with different channel lengths and JFET region widths are manufactured on three wafers and analyzed. The FN tunneling of gate oxide, HTGB and HTRB tests are performed and provide data support for the industrialization process for medium/high voltage SiC MOSFETs.
Risks of Innovation in the Architectural Design Process in Egypt: An Investigative Study
Authors: Medhat R , Othman A A E , Alamoudy F O
Published: August 2022

Achieving sustainability in construction projects is becoming an increasing priority worldwide. Being one of the crucial phases of the construction process, the design process plays a major role in achieving the goals of sustainability. Adopting innovative design solutions is a promising way of enhancing the sustainable performance of buildings. However, the implementation of innovative solutions is risky and needs to be managed carefully to avoid failure. Due to the increasing number of construction projects being developed in Egypt and because of the need to achieve the Sustainable Development Strategy (SDS) 2030, adopting innovative solutions became an essence. Accordingly, this research aims to investigate the risks associated with innovative solutions during the design process. In order to achieve this aim, a research methodology consisted of literature review and case studies was designed to achieve three objectives. First, to build a comprehensive background about the research topic including the concepts of sustainability, innovation and innovation risks, and the design process. Second, depict the relationship between innovation risks, the architectural innovation aspects, architectural design process and sustainability aspects. Final, present and analyze three case studies to explore the innovation management strategies adopted to overcome the risks associated with the adopted innovation solution.
Introducing the Architecture Parametric Design Procedure: From Concept to Execution
Authors: Khamis Ahmed A. , Ibrahim Sherif A. , Khateb Mahmoud A. , Abdel-Fatah Hesham , Barakat Mohamed A.
Published: August 2022

The parametric design process is one of the modern architectural trends. It assists in the decision-making process during the early conceptual design stage. It introduces several design alternatives from which the designers can choose to achieve the most suitable design concept. Through this process, the BIM (Building Information Modelling) is considered as the stage of converting the preferred design concept to execution drawings and building information. Furthermore, the computerized digital fabrication stages will assist in building the desired model in different scales for the final decision to be taken. This paper spotlight the overall parametric design process workflow from the “design stage” (using Grasshopper which is a plugin in rhino parametric design software) passing through the Revit software that is responsible for the working drawings execution to the “manufacturing stage” using Simplify 3D software for the preparation of the mock-up digital fabrication model using 3D printing.
VPL-based Code Compliance Checking for Building Envelope Design Using OTTV Calculation
Authors: Eid A S , Aboulnaga M M , Mahmoud A H
Published: August 2022

Building Envelope plays a vital role in reducing thermal loads, minimizing energy consumption, and ensuring sustainability. The Overall Thermal Transfer Value (OTTV) is a recognized method to evaluate the thermal performance of buildings. Building Information Modelling (BIM) has added great value to the AEC industry as an efficient tool to facilitate the building design process. With the development of BIM, more properties and material characteristics are assigned to the project design and building model that are getting more complex. Meanwhile, performing OTTV assessment and checking compliance with the assigned values involving time-consuming calculations with the possibility of ambiguity. Hence, automation of the code compliance checking process has become on-demand within the BIM environment. The objective is to develop a Visual Programming Language (VPL)-based script for automating the OTTV rule-based code compliance checking process. The applied method is to integrate BIM, VPL, and OTTV requirements; and develop a visual script that is responsible for extracting parameters from the BIM model, performing OTTV calculation, comparing output with assigned standard values of OTTV aiming answering the research question whether automated code compliance checking process can contribute to code compliance facilitation effectively. The results indicate that integrating VPL into the code compliance checking process has promising signs in facilitating the compliance checking process, increasing the accuracy and reliability of outcomes.
Monitoring lava dome extrusion of Merapi Volcano during 2018-2019, using low-cost UAV application
Authors: Putra Raditya , Harijoko Agung , Santoso Agus Budi
Published: August 2022

Merapi volcano has a well-known eruption type, namely Merapi type, in which an extruded lava dome collapses and is accompanied by pyroclastic density current (PDC). This type of eruption makes morphological monitoring of the lava dome crucial in the hazard mitigation process. After the VEI 4 eruption in 2010, a new lava dome of Merapi appeared on top of the 2010 lava dome in August 2018 and continuously grew. In November 2019, the lava dome started to collapse outward the crater area. We reported the lava dome morphological monitoring using a UAV (Unmanned Aerial Vehicle) photogrammetry conducted from August 2018 to February 2019. This UAV monitoring provides processed aerial photo data in Digital Terrain Model (DTM) and orthophoto with low operating costs and short data acquisition time. The lava domes erupted from the same eruptive canter within this period and grew evenly in all directions. The 2018-2019 Merapi lava dome has basal ratio of 0.183 to 0.290 with height of 11 to 41 m, respectively. Volume changed from 33,623 m3 in August 2018 to 658,075 m3 in February 2019, suggesting growth rate at ~3,500 m3/day. The lava base filled the crater base area (0.21 km2) and started to collapse outward in November 2019.
Landslide susceptibility zone in steep slope landscape at Gunung Kidul Regency, southeast part of Yogyakarta, Indonesia
Authors: Saenkang Phoulid , Setiawan Hendy
Published: August 2022

Gunung Kidul is located in Central Java Province, Indonesia. which is vulnerable to geological hazard such as floods and earthquake. However, it is also susceptible to landslide in some areas of Gunung Kidul which contributes to damage and loss. The study area is covers sub districts such as: Patuk, Gedangsari, Nglipar, Ngawen, Playen. It covers an area of 1,485.36 km2 and had a population of 747,161 at the 2020 Census. This research aims to produce a landslide susceptibility map, construct the detailed geological map, consider geomorphology aspect, lithology aspect, soil-rock masses, hydrogeology/groundwater aspect, structural geology aspect, land use. The parameters that caused the occurrence of landslide were determined and the landslide susceptibility map was produced using Weightage Overlay Method (WOM) in ArcGIS software. Results showed that the susceptibility map was classified into three zones which is low, moderate and high zone. The factor that triggered the landslide were identified which is heavy rainfall intensity and earthquake. As a conclusion, the ability to detect landslide susceptibility led to a better understanding of landslide mechanisms for the research area, thus leading to an enhanced identification of the most likely failure sites within a landslide-prone area.
The pre-liminary study on surface modification of magnetite for microplastic removal from water
Authors: Phengsaart T , Phradub P , Tonabut W , Ekasin J , Katethol P , Sirisetpakdee P , Pimolrat J , Juntarasakul O , Soonthornwiphat N , Saisinchai S
Published: August 2022

Microplastics (MPs), the plastic particles with size fraction smaller than 5 mm, are recently becoming one important problem worldwide due to their ubiquitous distribution in the environment, especially in water. In this study, the separation techniques in mineral processing (i.e., magnetic separation and surface-based separation) were applied to remove MPs from contaminated water. Five kinds of model MPs samples (+38−2000 μm); polypropylene (PP), polyethylene (PE), polystyrene (PS), polyethylene terephthalate (PET), and polyvinyl chloride (PVC) were used and magnetite (Fe3O4) powders (−75 μm) were modified using hexadecyltrimethoxysilane (HDTMS) to change their surface from hydrophilic to hydrophobic for MPs recovery. The results showed that MPs could be attached on the surface of modified magnetite due to the hydrophobic interaction and could be recovered together with modified magnetite by magnetic separation.
Spatial distribution and pattern of heavy metals in urban soils of Yogyakarta, Indonesia
Authors: Magno J L , Budianta W
Published: August 2022

Heavy metals contamination is becoming a global problem in urban areas. With that, understanding spatial distribution and pattern of heavy metals in urban soils is a crucial step toward sustainable urban development. This study intends to assess the spatial distribution and pattern of four heavy metals (Pb, Cu, Zn, and Cd) in Yogyakarta City outward in the boundaries of Sleman and Bantul Regencies. In relation, we utilized geostatistical method Empirical Bayesian Kriging (EBK) then correlated to Land Cover/Use data for the spatial analysis of heavy metals concentration. The degree of contamination was quantified using indices - PI (Pollution Index), Igeo
(Geo-accumulation Index), and PLI (Pollution Load Index). We show that by analysing the Pb, Cu, Zn, and Cd elements of 168 urban soils samples collected, Yogyakarta City, a densely populated area, serves as a place of heavy metals contamination hotspots. Pb and Cu is posed as moderately contaminated, whereas Zn and Cd is considered as uncontaminated (as majority of Zn and Cd values does not exceed the background values). But in overlapping consideration of four heavy metals contamination, they are classified as moderately contaminated (PLI=1.10). In summary, heavy metals contamination in soils varies as a function of urbanization.
Influence of coastal alluvial aquifer on groundwater chemistry in Wates, Yogyakarta, Indonesia
Authors: Thin P P , Hendrayana H , Kawasaki S
Published: August 2022

Saline groundwater is found far from the coastline, whereas closer groundwater has low salinity in the Wates area, Indonesia. This situation which has led to problems linked to the coastal aquifer, shows different groundwater chemistries. This connection needs to highlight the geochemical evolution of aquifers. This research aims to evaluate the hydrochemical characteristics in Wates Sub-District, Kulon Progo District, Indonesia. The study area is located in the southern part of the Kulon Progo with an aquifer of marine and fluvial deposits. The boundary of the south is the Indian Ocean. The approach is based on analyzing the major ions of 27 groundwater samples, and the XRD results include the Stiff diagram and the Stuyfzand classification. The Stiff diagram showed in agreement with that of the Stuyfzand classification. Results showed that the F2-(CaHCO3)2Ø and F1-(NaMix)Ø types reflect the recharge process and dominate the dissolution of silicate minerals. Halite dissolution originates in topographically flat areas of the Bs1-NaCl (-) water. Total hardness is softer than others as a result of cation exchange. The groundwater chemistry’s geochemical processes are the dissolution of silicate and halite minerals, ion exchange, and fresh and seawater mixing. This research indicates to focus on pumping problems in the aquifer.