bluuebunny/crossref_metadata_2025_split huggingface dataset:
Localised edge‐region‐based active contour for medical image segmentation
Authors: Liu Hua‐Xiang , Fang Jiang‐Xiong , Zhang Zi‐Jian , Lin Yong‐Cheng 
Published: January 2021

AbstractSegmenting the region of interest (ROI) from medical images is a fundamental but challenging task due to the illumination change and imaging devices. Although many models based on the local region‐based active contour model (LR‐ACM) are proposed to deal with intensity inhomogeneity, it is still difficult for the global energy‐based ACM with local image information to accurately extract the ROI from medical images. To solve this problem, this study proposes a novel localised ACM by constructing the gradient information based on the probability scores from the fuzzy k‐nearest neighbour classifier. Different from the traditional LR‐ACMs, our model is based on local rather than global image statistics, where a probability score‐based edge detector is directly used for gradient information. The energy functional consists of localised region energy and an edge energy. By introducing a local characteristics function, the localised region energy with the probability‐score‐based edge information is formulated, which can make the evolution curve stop on the exact boundaries of ROI. The edge energy including the regularisation and the penalty terms is used to avoid the reinitialisation process and smooth the evolution curve during evolution. To maintain the signed distance property of the evolution curve, a novel potential function in the penalty term is designed, which can consistently control the diffusion direction of the evolution curve. Experiments on the medical images including the cardiac magnetic resonance imaging and the 3DIRCADb databases demonstrate that the proposed model is more robust and accurate to extract the ROI than the popular localised and region‐based ACMs. The code is available at: https://github.com/HuaxiangLiu/Localized_ERAC/.
Rapid and environment‐friendly preparation of silver nanoparticles and their inhibition against phytopathogenic fungi
Authors: Zhao Lei , Gong kun , Wang Yue , Kong Shuang 
Published: January 2021

AbstractMicrobial‐assisted biosynthesis of silver nanoparticles (AgNPs) has been developed rapidly in recent years, but their mechanism of synthesis and production are still unknown. This study investigated the roles of nitrate reductase produced by the fungus Trichoderma asperellum in the synthesis of AgNPs. The nitrate reductase activity is activated by nitrate and showed a positive correlation with the quantity of AgNPs, which may lead to the development of a fast bioprocess of AgNPs synthesis. Treatment of silver nitrate with the fungal supernatant containing nitrate reductase produced stable, monodispersed, and spherical AgNPs with an average size of 20 nm, which were characterized by UV–visible spectroscopy, scanning electron microscopy and X‐ray diffraction. SDS‐PAGE implied that nitrate reductases were involved in the synthesis of AgNPs. The antifungal activities of synthesized AgNPs solution were compared with those of silver nitrate solution and AgNPs‐free supernatant solution. The results showed that AgNPs solution exhibited the highest antifungal activity against several selected plant pathogens by the agar well diffusion method. This study firstly concluded that extracellular biosynthesis of AgNPs could be promoted by potassium nitrate in Trichoderma asperellum Q1 media and the AgNPs provided a potential enhancement of biocontrol activity derived from the fungi.
Improved photovoltaic performance of dye‐sensitized solar cells using dual post treatment based on TiCl4 and urea solution
Authors: Bolag Altan , Wang Qiaoling , Liu Linan , Jamiyansuren Tumenkhuslen , Tumurpurev Ugtakhbayar , Tuvjargal Norovsambuu , Bao Tana , Ning Jun , Alata Hexig , Tegus Ojiyed 
Published: January 2021

AbstractAn effective and efficient photovoltaic performance is significantly affected by the interface between different constituents of dye sensitized solar cells (DSSC). A novel dual post treatment of TiCl4 and urea solutions on different layers of TiO2 electrode is addressed and the TiO2 particle morphology, dye‐adsorption amount on the TiO2 electrode and the photovoltaic performance of the DSSC based on those electrodes are characterised in this work. TiCl4 treatment can form more binding site on TiO2 particles and urea treatment structures a thin layer of g‐C3N4 on the surface of TiO2 particles. This strategy can not only effectively increase the dye‐adsorption for light‐harvesting, but also facilitate the electron transfer through inhibiting the charge recombination between TiO2 and electrolyte, and moreover, it provides excess electrons for the photoanodes. The DSSC fabricated from TiO2 electrode processed with urea treatment on the sixth layer exhibited the highest power conversion efficiency of 8.94% with a short current density Jsc of 24.09 mA cm–2, an open circuit voltage Voc of 583 mV and a fill factor of 63.8.
Comparative analysis of switching losses and current ripple of continuous and discontinuous SVPWM strategies for unbalanced two‐phase four‐leg VSI Fed unsymmetrical two‐phase induction motor
Authors: Muangthong Kaset , Charumit Chakrapong 
Published: January 2021

AbstractThis paper presents a comparative analysis of the continuous space vector pulse width modulation and the discontinuous space vector pulse width modulation in terms of the switching losses and current ripple reduction for the unbalanced two‐phase four‐leg voltage source inverter fed unsymmetrical two‐phase induction motor. The main function of both space vector pulse width modulation strategies is to produce unbalanced two‐output voltages with constant phase shift of 90° for main and auxiliary windings. The discontinuous space vector pulse width modulation principle is modified from a traditional two‐phase four‐leg voltage source inverter by placement of the space vectors to alternatively eliminate zero space vector in each switching sequence. As a consequence, the proposed unmodulation region or clamping zone of the discontinuous modulation strategy has 180° all the time. The experimental results illustrate the modulation waveforms of both methods, output voltage spectrum, normalized switching losses, output current ripple and inverter efficiency at high modulation index. The evaluation of the normalized average switching losses and the current ripple of the discontinuous space vector pulse width modulation method can be reduced more than that of the continuous space vector pulse width modulation method.
Unified centralised/decentralised frequency control structure for microgrids
Authors: de Godoy Paulo Thiago , de Almeida Adriano Batista , Marujo Diogo 
Published: January 2021

AbstractWhen the microgrid (MG) operates in islanded mode, the frequency adjustment is performed through the secondary control. This control can be achieved through centralised, distributed or decentralised strategies. The centralised strategies are the most applied in the MG due to the facility of the control and coordination of the distributed generations. However, due to centralisation of processing and information, these strategies depend on the continuous operation of the communication channels. The decentralised and distributed strategies are proposed in the literature to avoid the reliability issues of centralised strategies. This paper proposes a new control interface that can combine the centralised and decentralised secondary frequency control strategies in a unique control structure, merging the advantages of each technique. The proposed unified secondary frequency control structure (USFCS) can ensure the benefits of centralised control and can maintain the MG frequency regulation even during control or communication failures. The proposed USFCS is verified on an MG based on the CIGRE benchmark LV distribution network through simulation. The results have shown that the proposed control structure can guarantee the frequency regulation even during failures and can restore it to regular operation after failure.
Cascade‐IλDμN controller design for AGC of thermal and hydro‐thermal power systems integrated with renewable energy sources
Authors: Arya Yogendra , Kumar Nishant , Dahiya Pankaj , Sharma Gulshan , Çelik Emre , Dhundhara Sandeep , Sharma Mandeep 
Published: January 2021

AbstractExpert, intelligent and robust automatic generation control (AGC) scheme is requisite for stable operation and control of power system (PS) integrated with renewable energy sources (RES) under sudden/random small load disturbances. Large frequency deviations appear if AGC capacity is inept to compensate for the imbalances of generation and demand. In this paper, a cascade‐fractional order ID with filter (C‐IλDμN) controller is proposed as an expert supplementary controller to promote AGC recital adequately in electric power systems incorporated with RES like solar, wind and fuel cells. The imperialist competitive algorithm is fruitfully exploited for optimizing the controller parameters. First, a 2‐area reheat thermal system is examined critically and then to authorize the worth of the proposed controller, the study is protracted to a 2‐area multi‐source hydro‐thermal system. The prominent benefits of C‐IλDμN controller with/without renewable energy sources consist of its great indolence to large load disturbances and superiority over various optimized classical/fuzzy controllers published recently. The sensitivity study validates the robustness of the recommended controller against ±20% deviations in the system parameters and random step load perturbations.
Enhanced PI control and adaptive gain tuning schemes for distributed secondary control of an islanded microgrid
Authors: Zhang Yuanshi , Mohammadpour Shotorbani Amin , Wang Liwei , Mohammadi‐Ivatloo Behnam 
Published: January 2021

AbstractThis paper develops an enhanced proportional‐integral distributed control scheme (EPI‐DCS) to regulate the frequency and voltage of a droop‐controlled microgrid and share the power mismatch, simultaneously. The proposed EPI‐DCS is designed by using the control Lyapunov function method and adding a new consensus‐based term to the integrand dynamic of the conventional PI control. In the proposed distributed EPI‐DCS, the distributed generation units intermittently exchange information with the neighbouring distributed generation units, through a communication network. Considering the communication network time delays, the stability of the proposed EPI‐DCS is examined using the Lyapunov–Krasovskii linear matrix inequality conditions, and the maximum stable time delay is calculated. In order to stabilise the system for large destabilising time delays, an adaptive gain scheme is proposed. Effectiveness of the proposed adaptive EPI‐DCS is validated by numerical simulations with detailed models of the components and the converters, including load change, distributed generation outage, and adaptive gain‐scheduling against destabilising communication network time delays.
Quantitative analysis of sustained oscillation associated with saturation non‐linearity in a grid‐connected voltage source converter
Authors: Wu Tianhao , Jiang Qirong , Shair Jan , Xie Xiaorong , Wang Yanhui , Luo Yongzhi , Mao Hangyin 
Published: January 2021

AbstractThe interaction between the voltage source converter (VSC) and weak grid causes a negatively damped or diverging oscillation (DVO). The diverging oscillation generally evolves into a sustained oscillation (STO) when governed by the nonlinearities in the VSC's control system, such as the saturation of pulse width modulation (PWM). The conventional small‐signal impedance/admittance modelling (SSIM/SSAM) and stability analysis methods are not suitable for the characteristic analysis of STO. This paper presents a large‐signal impedance/admittance model (LSIM/LSAM)‐based quantitative analysis method to better understand the mechanism, characteristics, and occurrence conditions of STO. The LSAM extends the SSAM by incorporating the nonlinearity of PWM saturation using the describing function method. First, a unique time‐varying characteristic of the oscillation associated with nonlinearity is investigated. Then, two LSIM/LSAM‐based occurrence criteria for STO are established based on an equivalent RLC circuit model of the system. Three critical pieces of information, including the occurrence condition, frequency, and magnitude, associated with STO are revealed by the criteria. Finally, the LSAM‐based analysis method is applied to investigate the time‐varying admittance of the VSC and to assess the magnitude and frequency of STO. Both the criteria and LSAM‐based analysis results have been verified through time‐domain simulations on a typical grid‐connected VSC.
Effects of process parameters on the physicochemical properties of corn stalk hydrochar and the removal of alkali and alkaline earth metals
Authors: Yang Li , Wang Hui , Sun Jianwei , Xu Yiyun , Li Pengcheng , Xu Youning , Wu Shaohua 
Published: January 2021

AbstractThe advantages of the direct combustion of agricultural biomass for power generation are restricted due to the drawbacks of this biomass and the deep peak shaving trend. Hydrothermal carbonization can improve the physical and thermochemical properties of raw materials. Corn stalk samples were selected as the research object in this study. Corn stalk hydrochars were prepared with reaction pressures of 0–3 MPa, reaction temperatures of 160–240 °C, and residence times of 1–10 h. The effects of the process parameters on the physicochemical properties of hydrochar and on the removal of alkali and alkaline earth metals (AAEMs) were studied by measuring the hydrochar mass, energy yield, product composition, morphology, as well as the removal efficiency of AAEMs. The results indicated that the corn stalk hydrochar had higher mass and energy yields than the raw corn stalk. X‐ray diffraction showed that the carbon content in the hydrochar was greater than that in raw corn stalk. Scanning electron microscopy showed that the reaction temperature played a more significant role in the hydrothermal carbonization process than the reaction pressure and residence time.
Optimal power sharing of wind farms for frequency response
Authors: Tu Ganggang , Junyent‐Ferré Adrià , Xiang Ji , Barria Javier A. 
Published: January 2021

AbstractThis paper presents a uniform optimal power sharing strategy to coordinate the wind turbines (WTs) in a wind farm (WF) to provide occasional and continuous frequency response (FR). The coordination of WTs is formulated as an optimisation problem that takes into account the WT dynamics and tries to reduce the long term loss of energy yield caused by the provision of FR. This is achieved by maximising the total kinetic energy of the WF over time while reducing wear and tear of WTs. The proposed optimal power sharing strategy relies on periodic communication between each WT and a WF controller. Local linear approximations are employed to predict the system behaviour and the solution of the optimisation problem is obtained using the proposed centralised and/or distributed algorithm. The distributed algorithm only requires one‐way communication between the WF controller and local WTs, reducing the communication overheads. Simulation studies are carried out on a WF model to demonstrate the effectiveness of the proposed strategy. The results show the strategy enables reduction of yield loss over previous methods while avoiding over torque operation during FR provision.
The occurrence mechanism and damping method of ultra‐low‐frequency oscillations
Authors: Wang Peng , Li Baohong , Jiang Qin , Chen Gang , Han Xiaoyan , Dragicevic Tomislav , Liu Tianqi 
Published: January 2021

AbstractThe ultra‐low‐frequency oscillation (ULFO) problem has reappeared in China recently. Although the hydraulic generator is supposed to have a strong connection to this problem, the conditions for ULFO appearance and detailed reasons are not clear yet. In order to clarify the occurrence mechanism of ULFO, this paper studies each important part of hydraulic generator system, including the governor, exciter and power system stabiliser (PSS). The weak connection is confirmed to have an important impact on the occurrence of the ULFO. Nevertheless, by studying each device's contribution to ULFO through the complex torque coefficient method, it is shown that the negative damping effect of the hydraulic governor will cause the instability in the ultra‐low‐frequency band, while the exciter and the PSS have little influence on ULFO. Additionally, the proportional–integral parameters of the hydraulic governor system are also studied to clarify their influence on ULFO based on the complex torque coefficient method. Based on the above analysis, two damping methods for ULFO suppression are finally proposed. To verify theory and damping methods, the simulations are implemented in PSCAD and PSASP software.
Real‐time energy management system for public laundries with demand charge tariff
Authors: Deng Runze , Luo Fengji , Ranzi Gianluca , Qiu Jing 
Published: January 2021

AbstractA building energy management system can be defined as a building automation system that can facilitate demand response by controlling building‐side energy resources. Here, a real‐time Energy Management System (EMS) is developed to reduce the energy costs charged by the demand charge tariff for a specific commercial building that consists of a public laundry. The authors model the public laundry energy management problem as a multi‐task scheduling problem and design a set of algorithms to heuristically control the operations of washing machines and clothes dryers by taking into account the customer‐specified task requirements and the laundry owner's budget. Numerical case studies are conducted to validate the proposed EMS.
A technical review of the challenges of powder recycling in the laser powder bed fusion additive manufacturing process
Authors: Soundarapandiyan Gowtham , Johnston Carol , Khan Raja H.U. , Chen Bo , Fitzpatrick Michael E. 
Published: January 2021

AbstractLaser powder bed fusion (L‐PBF) is one of the most widely used additive manufacturing techniques for fabrication of components with complex geometries for various industrial applications including aerospace, medical and automotive. The unconsumed powder after part manufacturing is often recovered and recycled to improve process efficiency. However, some of the particles in the recycled powder can have different physical and chemical properties from those in the virgin powder owing to their exposure to the complex environment during the manufacturing process. In addition, some contaminants can be introduced in the recycled powder due to poor process control. A number of studies have been published in the past few years revealing the effects of powder recycling on the build properties. The present work aims to highlight the key phenomena during the manufacturing process that caused degradation to the recycled powder. Further to this, some comments, gaps and areas that deserve further detailed studies are also highlighted.
Epidemiological and Therapeutic Developments in Pelvic Ring Fractures Type C from 2004 to 2014 – a Retrospective Data Analysis of 2,042 Patients in the German Pelvic Register (DGU)
Authors: Lang Patricia , Schwabe Kerstin , Riesner Hans-Joachim , Friemert Benedikt , Stuby Fabian , Palm Hans-Georg ,   AG Becken III der Deutschen Gesellschaft für Unfallchirurgie
Published: January 2021

AbstractBackground Pelvic ring fractures type C present a special challenge due to their high instability, the possible accompanying injuries and the high mortality rate of up to 18.9%. The aim of this retrospective analysis was to use the data from the DGU pelvic register to identify changes in the epidemiology and therapy for type C pelvic ring fractures between 2004 and 2014.Materials and Methods 2,042 patients with type C pelvic ring injury were retrospectively included. Three time periods with roughly equal patient groups were specified and differences in epidemiology and the type of therapy were evaluated. For the surgical cases, the time of the operation, the duration of the operation, blood loss, the location of the fracture and the type of osteosynthesis were evaluated and the reduction result was recorded.Results For the period under review, there is an age shift in the incidence of a type C pelvic ring fracture towards older age. The isolated pelvic injury has increased, while the proportion of pelvic injuries in the context of polytrauma has steadily decreased. Complications and mortality decreased as a percentage. The tendency towards minimally invasive procedures could be shown in the surgical care. Navigated procedures in the area of the pelvic ring have so far not proven successful.Conclusions We were able to show that the majority of the patients are increasingly old, that there is no relevant trauma in the history and that there is an increase in the isolated pelvic fracture type C and a decrease in the number of polytraumatised or multiply injured patients. In conjunction with mortality from pelvic ring injuries, the successes of standardised, pelvic-specific emergency management, an adapted time of operation outside the vulnerable phase and stable osteosynthesis care, which enable early functional follow-up treatment, are also evident.
Nutzungsformen psychosomatischer Rehabilitation
Authors: von Kardorff Ernst , Meschnig Alexander , Klaus Sebastian 
Published: January 2021

Zusammenfassung
Hintergrund Die Studie untersucht die subjektiven Erwartungen an die psychosomatische Rehabilitation und die dort gemachten Erfahrungen im Verhältnis zum nachträglich eingeschätzten Nutzen für die Rückkehr in Arbeit (RTW). Ein besonderer Fokus liegt dabei auf den Verlaufskurven von Beginn der ersten Symptome an bis zur Klinikaufnahme und der dadurch beeinflussten Nutzung und Beurteilung der Maßnahme über den gesamten Krankheits- und Rehabilitationsverlauf bis zum RTW.
Ziele Im Kern zielt die Studie auf die individuellen und kontextbezogenen Bedingungen und Verläufe einer gelingenden Rückkehr an den Arbeitsplatz und eines nachhaltigen Verbleibs in Arbeit bei psychisch beeinträchtigten Rehabilitanden aus der retrospektiven verlaufsbezogenen Sicht der Betroffenen selbst. In diesem Beitrag steht die Frage nach den Erwartungen und dem Hilfebedarf beim Zugang zur medizinischen Rehabilitation und nach den Formen der Nutzung ihrer Behandlungsangebote in Abhängigkeit von der individuellen Problemkonstellation beim Zugang in die stationäre Rehabilitation im Zentrum.
Methode In der qualitativen Studie wurden 105 Teilnehmer zunächst mittels eines Fragebogens zu ihrer Situation am Beginn der Medizinischen Rehabilitation befragt. Von diesen wurden 33 auf Basis des theoretical sampling ausgewählte Personen, die den Interviews zugestimmt hatten mit episodisch-narrativen Interviews zu 3 Zeitpunkten nach Ende der Maßnahme (6, 12 und 18 Monate) befragt, Fallverläufe erstellt und miteinander verglichen.
Ergebnisse Es zeigten sich charakteristische Nutzungserwartungen an die psychosomatische Rehabilitation und darauf basierende unterschiedliche Nutzungsformen ihrer Angebote, die sich nur teilweise mit den Zielen der Rehabilitationsmedizin und den Angeboten der Kliniken decken. Dies verweist auf unterschiedliche Bedarfslagen, die mit dem Stand der Auseinandersetzung mit der Krankheit und anderen personalen Konstellationen korrelieren, in denen sich der Rehabilitand auf einer idealtypischen Verlaufskurve zum Zeitpunkt der Klinikaufnahme befindet. Darauf sollte sich das klinische Setting im Sinne eines personalisierten Case Management einstellen.