bluuebunny/crossref_metadata_2025 huggingface dataset:
Photoluminescence of Sn2+–I−-mixed molecular perovskites
Authors: Fan Guang-Meng , Shi Chao , Qiao Liang , Li Hao-Jie , Ye Heng-Yun
Published: July 2018

Sn2+–I− mixed molecular bistable perovskite crystals result in a tuning of the photoluminescence behaviour and so the multifunctional material.
Few-layered α-MoTe2 Schottky junction for a high sensitivity chemical-vapour sensor
Authors: Shackery Iman , Pezeshki Atiye , Park Jae Young , Palanivel Umadevi , Kwon Hyeok Jae , Yoon Hyong Seo , Im Seongil , Cho Jin Soo , Jun Seong Chan
Published: July 2018

For the first time, we connect in series two α-MoTe2-based Schottky diodes (SDs) to form a back-to-back diode using the micromechanical exfoliation method. Such structure shows excellent performance toward chemical vapor sensing.
One-step room-temperature exfoliation of graphite to 100% few-layer graphene with high quality and large size
Authors: Liu Ting , Zhang Xuesha , Liu Mengjie , Wu Wenyu , Liu Kang , Liu Yanyan , Gu Yu , Zhang Ruijun
Published: July 2018

A mechanistic scheme of room-temperature chemical exfoliation of graphite into graphene.
Highly efficient crystalline organic light-emitting diodes
Authors: Yang Xinxiao , Feng Xiao , Xin Jianhui , Zhang Panlong , Wang Haibo , Yan Donghang
Published: July 2018

An efficient crystalline organic light-emitting diode based on high-quality crystalline heteroepitaxy films has been constructed, which exhibits high efficiency.
Assembly of mammalian oxidative phosphorylation complexes I–V and supercomplexes
Authors: Signes Alba , Fernandez-Vizarra Erika
Published: July 2018

The assembly of the five oxidative phosphorylation system (OXPHOS) complexes in the inner mitochondrial membrane is an intricate process. The human enzymes comprise core proteins, performing the catalytic activities, and a large number of ‘supernumerary’ subunits that play essential roles in assembly, regulation and stability. The correct addition of prosthetic groups as well as chaperoning and incorporation of the structural components require a large number of factors, many of which have been found mutated in cases of mitochondrial disease. Nowadays, the mechanisms of assembly for each of the individual complexes are almost completely understood and the knowledge about the assembly factors involved is constantly increasing. On the other hand, it is now well established that complexes I, III and IV interact with each other, forming the so-called respiratory supercomplexes or ‘respirasomes’, although the pathways that lead to their formation are still not completely clear. This review is a summary of our current knowledge concerning the assembly of complexes I–V and of the supercomplexes.
Mitochondrial transcription and translation: overview
Authors: D’Souza Aaron R. , Minczuk Michal
Published: July 2018

Mitochondria are the major source of ATP in the cell. Five multi-subunit complexes in the inner membrane of the organelle are involved in the oxidative phosphorylation required for ATP production. Thirteen subunits of these complexes are encoded by the mitochondrial genome often referred to as mtDNA. For this reason, the expression of mtDNA is vital for the assembly and functioning of the oxidative phosphorylation complexes. Defects of the mechanisms regulating mtDNA gene expression have been associated with deficiencies in assembly of these complexes, resulting in mitochondrial diseases. Recently, numerous factors involved in these processes have been identified and characterized leading to a deeper understanding of the mechanisms that underlie mitochondrial diseases.
Nature of the sedimentary rock record and its implications for Earth system evolution
Authors: Husson Jon M. , Peters Shanan E.
Published: July 2018

The sedimentary rock reservoir both records and influences changes in Earth's surface environment. Geoscientists extract data from the rock record to constrain long-term environmental, climatic and biological evolution, with the understanding that geological processes of erosion and rock destruction may have overprinted some aspects of their results. It has also long been recognized that changes in the mass and chemical composition of buried sediments, operating in conjunction with biologically catalyzed reactions, exert a first-order control on Earth surface conditions on geologic timescales. Thus, the construction and destruction of the rock record has the potential to influence both how Earth and life history are sampled, and drive long-term trends in surface conditions that otherwise are difficult to affect. However, directly testing what the dominant process signal in the sedimentary record is — rock construction or destruction — has rarely been undertaken, primarily due to the difficulty of assembling data on the mass and age of rocks in Earth's crust. Here, we present results on the chronological age and general properties of rocks and sediments in the Macrostrat geospatial database (https://macrostrat.org). Empirical patterns in surviving rock quantity as a function of age are indicative of both continual cycling (gross sedimentation) and long-term sediment accumulation (net sedimentation). Temporal variation in the net sedimentary reservoir was driven by major changes in the ability of continental crust to accommodate sediments. The implied history of episodic growth of sediment mass on continental crust has many attendant implications for the drivers of long-term biogeochemical evolution of Earth and life.
BAT algorithm inspired retinal blood vessel segmentation
Authors: Sathananthavathi Vallikutti , Indumathi Ganesan
Published: July 2018

The automated extraction of retinal blood vessels is the course of action in the medical analysis of retinal diseases. The proposed methodology for the retinal vessel segmentation is based on BAT algorithm and random forest classifier. A feature vector of 40‐dimensional including local, phase and morphological features is extracted and the feature set which minimises the classifier error is identified by BAT algorithm. The selected features are also identified as the dominant features in the classification. Performance of the proposed method is analysed by the publicly available databases such as digital retinal images for vessel extraction and structured analysis of the retina. The authors’ proposed method is highly sensitive to identify the blood vessels, in view of the fact that it corresponds to the ability of the method to identify the blood vessels correctly. BAT algorithm‐based proposed method achieves very high sensitivity and accuracy of about 82.85 and 95.34%, respectively.
Retracted: Robust retinal vessel segmentation using vessels location map and Frangi enhancement filter
Authors: Shahid Muhammad , Taj Imtiaz A.
Published: July 2018

The following article published in IET Image Processing, Shahid, Muhammad; Taj, Imtiaz A.: ‘Robust retinal vessel segmentation using vessels location map and Frangi enhancement filter’, IET Image Processing, 2018, DOI: 10.1049/iet‐ipr.2017.0457 on 16th January 2018 has been retracted due to a breach of the IET's Policy in Relation to Plagiarism, Infringement of Copyright and Infringement of Moral Rights and Submission to Multiple Publications. Prof. Imtiaz Ahmed Taj was unaware of and not complicit in any misconduct.
Average‐value model of micro gas turbine systems and its application to online validation of service restoration schemes
Authors: Hong Zeqi , He Jinghan , Xu Yin , Tao Lingyun , Wang Xiaojun
Published: July 2018

Distributed generators (DGs) within distribution systems can be used as emergency sources to restore critical loads during a major outage caused by extreme events. Since the capacity of DGs is limited, the dynamic performance of DGs needs to be validated by simulations before executing restorative strategies. Currently, many DGs use power electronic converters for grid connection. Therefore, electromagnetic transient (EMT) simulation is needed to study their transient characteristics for feasibility evaluation of service restoration plans. However, the detailed models of converters, which model each individual switch, are time consuming for EMT simulation, unsuitable for the purpose of online validation. This study first develops a simplified model of micro gas turbine (MTG). Then the dynamic average‐value modelling technique is used to construct the average‐value model (AVM) of grid‐connected converters. Finally, the MTG generation system model is integrated into a distribution system model for feasibility evaluation of restoration strategies. A radial test system including three MTG generation systems is utilised to validate the effectiveness of the proposed model. The numerical simulation results indicate that compared with the detailed model, the AVM improves the efficiency of simulation while still accurately predicts the transient behaviours of MTG generation systems. The proposed model is applicable for the online validation of restoration strategies.
Future standardisation requirements for dependable overcurrent protection in intentionally islanded LV microgrids build by distributed inverters
Authors: Wippenbeck Tilman , Willenberg Dominik , Schmidt Thomas , Schnettler Armin
Published: July 2018

The preconditions for dependable overcurrent protection of customer installations are largely unknown in islanded low‐voltage (LV) microgrids build by multiple droop controlled and current limited inverters. Consequences may be an islanded operation with limited reliability of supply, investments of uncertain necessity or uncontrolled hazards. Distribution system operators will not opt for intentional islanding until those risks become predictable. Extensive variation studies are therefore performed to screen for decisive influencing factors and to quantify their effect by means of computer simulations in Matlab/Simulink®. First steps of a standardisation roadmap are drawn that will either enable developing the preconditions for a dependable overcurrent protection or choosing effective alternatives. An initial set of quantitative minimal conditions is given as a basis for further discussions.
Deploying correct fault loop in distance protection of multiple‐circuit shared tower transmission lines with different voltages
Authors: Bak Claus Leth , Faria da Silva Filipe
Published: July 2018

Combined faults occurring between different voltage levels in overhead lines present a challenge for distance protection. Previous work has shown that such faults most often appears as single‐phase‐to‐ground (SPTG) faults in a normal type of overhead line. However, it is not obvious that distance relays will identify and select the correct fault loop according to being similar to SPTG, as all six fault loops get excited when combined faults occur. A study where two distance relays of different manufactures are tested using transient replay and secondary test equipment is presented, in order to reveal which fault loops are activated and whether a safe trip for combined faults happens.
Travelling waves‐based fault location scheme for feeders in power distribution network
Authors: Shi Shenxing , Lei Aoyu , He Xin , Mirsaeidi Sohrab , Dong Xinzhou
Published: July 2018

Fault location in distribution systems is difficult for multiple discontinuities, such as branch and junction points on feeders. This paper proposes a scheme for fault location in distribution systems using network topology information and circuit breaker reclosure‐generating travelling waves. Based on the topology information, the circuit breaker closure‐generating travelling waves can be got through analysis. When a permanent fault occurs, the circuit breaker reclosure‐generating travelling waves contain the information on fault position. In this paper, the difference between the pre‐fault travelling waves and post‐fault travelling waves induced by the breaker reclosing in a feeder, defined as reclosing superimposed travelling waves, is calculated. For the reclosing superimposed travelling waves, the initial travelling wave reflects the fault distance. Subsequently, wavelet transform is applied to extract the travelling wave reflected from the fault point. Finally, the time difference between the reclosing instant and the arrival instant of the reflected travelling wave is employed to calculate the fault distance. In order to verify the effectiveness of the proposed scheme, several simulations were carried out using ATP‐EMTP software. The simulation results indicated that the proposed scheme can be effective in fault location for distributed feeders, regardless of grounding system type.
Implementation of a process bus based feeder protection and measurement system operating as alternate protection at CTEEP's Embu‐Guaçu substation
Authors: Oliveira Lucas B. , Bittencourt Annelise A. , Matos Rafael R. , Marcello Nilton C.
Published: July 2018

This study describes the main results obtained from the deployment and commissioning of the feeder's protection and measuring system based on analogue and digital acquisitions by concentrator Merging Units. The presented project is installed at the Embu‐Guaçu substation, owned by CTEEP, on the AL‐60 feeder. The system architecture, protection functions used, network architecture and data segregation strategies, as well as results obtained in the laboratory and in the field from the operating system, are presented. The pilot project deployment experience with Merging Unit acting effectively to generate trip on the system and to act on the circuit breaker is innovative in Brazil.
Innovative solution for overcurrent relay coordination studies in power delivery networks using optimisation techniques
Authors: Papaspiliotopoulos Vasileios A. , Korres George N.
Published: July 2018

This study presents a software package developed to carry out overcurrent (OC) protection coordination studies for power delivery networks, making use of versatile optimisation models and robust solvers. The problem of setting and coordinating OC functions in modern numerical relays is formulated as a minimisation problem, subject to technical constraints which are relevant to the protection practises applied by utilities. The proposed solution aims to assist protection engineers in calculating optimum OC setting values, which is a labour‐intensive task.
Performance of out‐of‐step tripping protection under renewable integration
Authors: Liu Gaoyuan , Azizi Sadegh , Sun Mingyu , Popov Marjan , Terzija Vladimir
Published: July 2018

In future power systems, highly increased renewable integration is expected to meet global decarbonisation targets. The risks and uncertainties brought about by renewable integration will challenge system stability. This study analyses the impact of the increased level of renewable energy sources integration on system transient stability and out‐of‐step tripping (OST) protection. To this end, the performance of OST protection is assessed in terms of the ability to prevent system instability under different contingencies. A modified two‐area test system and Great Britain (GB) 29‐zone system integrated with a dynamic model of wind turbines are selected as test systems. A systematic approach is adopted to design a specific OST protection scheme for each test system and to obtain suitable relay settings. An extensive number of simulation studies are carried out using DIgSILENT PowerFactory to assess the performance of the designed schemes under different renewable integration levels. Conclusions are made based on the obtained results, which all imply that revision of the existing OST protection scheme will be inevitably needed.
Distributed signal processing units for centralised substation protection and control
Authors: Hohn Fabian , Rabuzin Tin , Wang Jianping , Nordström Lars
Published: July 2018

Substation automation systems are characterised by a high degree of functional integration, which can lead to a centralised substation protection and control (CPC) architecture. Most CPC architectures utilise merging units to interface with current and voltage transformers, which causes a high‐communication load on the process bus in case of large substations. This study proposes a CPC architecture based on distributed signal processing units (DSPUs) to overcome those drawbacks by publishing the results of the signal processing algorithms directly. The reduction of the communication load through the usage of DSPUs has been shown in a case study, which uses a 16‐bay transmission substation topology as a reference.
Application of distance protection in mixed overhead‐underground distribution feeders with distributed generation
Authors: Tsimtsios Aristotelis M. , Nikolaidis Vassilis C.
Published: July 2018

This study applies distance protection to real mixed overhead‐underground distribution feeders, as an alternative to conventional overcurrent protection schemes. The efficiency of the proposed distance‐based protection scheme is examined both in the radial (normal state) and in the looped operation of the distribution feeders. Moreover, distributed generating units of various types are assumed connected to the feeders to investigate their effect on the efficiency of the protection scheme. The latter proved sufficient to coordinate properly with the other protection means in the system, following a fuse‐blowing philosophy, providing reliable protection to the lines.
High impedance fault modelling and application of detection techniques with EMTP‐RV
Authors: Nikolaidis Vassilis C. , Patsidis Angelos D. , Tsimtsios Aristotelis M.
Published: July 2018

The aim of this study is to develop a software‐oriented framework that will help simulate and study high impedance faults (HIFs) in power distribution systems, as well as design adequate HIF detection techniques. After a thorough literature review, three well‐established HIF models have been developed in EMTP‐RV, as part of this work. Systematic (black box) modelling is applied so that each developed HIF model can be used in any power system under investigation in the future. An overview of the mostly available HIF detection methods is also included in this study, which subsequently concludes with the development of two proper HIF detection techniques in EMTP‐RV/MATLAB environment. A real 20 kV radial overhead distribution line located in Xanthi, Greece is modelled in EMTP‐RV and several HIFs at various time and locations are simulated. The simulation results are presented in order to evaluate the accuracy of the developed HIF models and the effectiveness of the developed HIF detection techniques.
Detailed analysis of the future distribution network protection issues
Authors: Khan Md Asif Uddin , Booth Campbell D.
Published: July 2018

This study will present the results of several simulation‐based analyses investigating the performance of distribution network protection under a range of future scenarios. It is widely accepted that the integration of a significant amount of distributed generation, often from renewable energy sources and interfaced to the main network via power electronics converters, will be commonplace in the future. Furthermore, at the transmission level, the interconnection of different countries through HVDC links and the decommissioning of many large‐scale conventional synchronous generators will result in the power systems becoming progressively weaker in terms of reduced faults level and lower system inertia. This study will, therefore, illustrate and emphasise the challenges and issues that arise in future distribution networks protection due to reduced system strength, fault level and the changing nature of the contribution (both in terms of magnitude and possibly delay in provision) to fault levels and the possible impact this may have on traditional overcurrent‐based protection schemes by building a simple model of distribution network in Simulink, MATLAB. In addition to that, the paper will also discuss some potential solutions as novel schemes to tackle the arising protection related problems.
Estimation of travelling wave arrival time in longitudinal differential protections for multi‐terminal HVDC systems
Authors: Johannesson Niclas , Norrga Staffan
Published: July 2018

Multi‐terminal high‐voltage DC (HVDC) systems equipped with HVDC breakers require that detection and clearing of faults occur within a few milliseconds. Although detection without communication is generally preferred with regard to detection delay and simplicity, detection schemes relying on communication can enhance the overall performance due to their reliability. One such principle is the travelling wave differential protection that is based on the comparison of waves at both ends rather than solely on current. However, as with conventional differential protections, some kind of synchronisation must be applied to properly compensate for the time difference between samples obtained at different geographical locations. In this study, a synchronisation algorithm is presented that applies real‐time signal processing to automatically obtain a proper compensation between the signals from both ends. The algorithm is examined by injection of data samples, generated from the simulation of an external fault in a PSCAD/EMTDC model. Additionally, the suitability for a real‐time implementation is evaluated by execution time estimation using a simulated DSP. The algorithm is found to perform well, not only in identifying the compensation delay but also in terms of computational efficiency, thus allowing for real‐time application.
Fault current control methods for multi‐terminal DC systems based on fault blocking converters
Authors: Ruffing Philipp , Brantl Christina , Petino Cora , Schnettler Armin
Published: July 2018

Within the framework of modernisation of the European electricity grid, multi‐terminal high‐voltage direct current (HVDC) offshore grids shall be integrated into future transmission systems. An essential aspect of multi‐terminal HVDC systems is fast and selective DC‐side fault handling and the separation of faulty lines. This study investigates the applicability of different control methods relying on full‐bridge‐based converters in combination with high‐speed switches for a fast and selective separation of faulty line segments in a multi‐terminal HVDC cable system in a symmetrical monopole configuration. It is shown that the proposed line current control method can significantly reduce the separation time of a faulty line compared with standard fault control methods. The analysis is based on simulations in PSCAD|EMTDC™ with a converter model based on the CIGRÉ WG B4.57, which is enhanced for the use of full‐bridge converters with fault current control schemes.
Hardware‐in‐the‐loop tests on distance protection considering VSC fault‐ride‐through control strategies
Authors: Jia Jundi , Yang Guangya , Nielsen Arne Hejde , Roenne‐Hansen Peter
Published: July 2018

The short‐circuit response of a voltage source converter (VSC) can vary from each other significantly with different control strategies. This study investigates the performance of distance protection under unbalanced faults considering two control strategies during fault‐ride‐through using hardware‐in‐the‐loop tests. Variations on fault type, converter current limit, fault resistance and pre‐fault power flow conditions are also examined. The tests reveal that the error in measured impedance caused by fault resistance will be enlarged in a converter‐dominated power system. The first control strategy tends to cause overreach problem while the second can raise both overreach and underreach problems. The indeterminacy associated with the second strategy is jointly affected by control parameters, converter current limit, fault resistance and pre‐fault power flow conditions. The findings of this study can help to stipulate grid requirements under unbalanced faults.
Increasing sensitivity for transformer protection using incremental differential
Authors: Magrin Fabiano , Tavares Maria Cristina
Published: July 2018

This study presents a new protection element that can increase transformer differential sensitivity. The new element, called incremental differential, takes the differential currents, operation and restraint currents and, using a new mathematical approach, it can be more sensitive than the standard differential. The study presents the mathematical calculation and how the incremental differential handles with the errors involved in the differential protection. It also presents the algorithm response for some fault cases, always comparing the element to the standard differential algorithm. As the new element is simple in a mathematical concept, the protection element was developed inside a commercial relay just using the manufacturer programming language and the users’ available programming area. The contributions of this work are the method to increase sensitivity using the same variables already available in differential relays, and the possibility to use the algorithm in a field installed relay.
Performance of fault‐level estimation functions in future distribution networks
Authors: Ahmed Muhanad , Booth Campbell , Coffele Federico
Published: July 2018

This study presents an evaluation of the impact of distributed generation, of varying capacity and connected at different locations, on existing system fault‐level estimation algorithms. A number of case studies have been simulated under different scenarios with DGs connected at different points on a 33/11 kV test network. Results show estimation errors when DGs are located downstream the fault‐level measurement point and the errors are proportional to the assumed level of fault contribution from the DG. Errors were found to increase when the DGs were located electrically closer to the measurement/fault‐level estimation point. Negligible errors were seen with the DG connected ‘upstream’ from the monitoring location. Possible solutions are discussed such as the use of distributed measurements to account for downstream DG fault levels. An approach to peak make fault‐level estimation is also described utilising current IEC short‐circuit calculation methods.
HVDC protection criteria for transient stability of AC systems with embedded HVDC links
Authors: Gonzalez‐Torres Juan Carlos , Costan Valentin , Damm Gilney , Benchaib A. , Bertinato Alberto , Poullain Serge , Luscan Bruno , Lamnabhi‐Lagarrigue Françoise
Published: July 2018

In recent years, different protection strategies for high‐voltage direct current (HVDC) grids have been developed by the industry and academia for the reliable and safe operation of direct current grids. The proposed strategies have different impacts on the AC networks where HVDC grids are connected. In the case of embedded HVDC grids embedded in a synchronous AC network, a partial loss of the HVDC grid might cause the desynchronisation of the AC grid. Therefore, it is of utmost importance to assess the impact of those protection strategies into the stability of the whole network. The objective of this study is to propose a methodology for the transient stability assessment of a simple but representative AC grid in case of DC fault. After validation of the methodology, some HVDC link protection criteria are defined in terms of the Critical Time to Return to Operation. These criteria will be helpful for the design of HVDC protection systems or for the sizing of future HVDC links in order to respect the constraints of the existing protection strategies.
Study on the estimation method of minimum ESS capacity considering frequency and voltage protection
Authors: Kim Ji‐Soo , Oh Yun‐Sik , Cho Gyu‐Jung , Kim Min‐Sung , Kim Chul‐Hwan , Funabashi Toshihisa
Published: July 2018

As the penetration of Renewable Energy Sources (RESs) increases, the countermeasures are becoming increasingly important because output of the RES is intermittent. Therefore an Energy Storage System (ESS) that can control generation is attracting attention and undergoing various studies in order to stabilize efficiently the output of the RES. The conventional method estimates the capacity of the ESS through error of actual data of the RES's power and reference point using moving average method. However, as the error between reference power and output power of the RES increases, the capacity of the ESS increases. Therefore, in this paper, we propose method for estimating the capacity of the ESS using the improved moving average method.
Fast phase selection method based on transient current for UHV transmission lines
Authors: Luo Sibei , Gao Houlei , Wu Yuehua , Huang Jiakai , Wang Dong
Published: July 2018

Ultra‐high‐voltage (UHV) transmission lines have a higher requirement for selecting faulted phases fast and reliably. The coupling relationship between the three phases is analysed in detail. On the basis of the coupling relationship, the principle of faulted phase selection (FPS) is proposed, which utilises the time‐domain energy of three‐phase transient currents. To remove high‐frequency noise and preserve the transient current waveform features invariant, a morphological filter with flat structure element is applied in FPS algorithm. The simulation model of Jindongnan–Nanyang–Jingmen UHV transmission project is established in EMTP. The testing results show that the proposed algorithm is feasible and fast (<2 ms) in case of various fault conditions.
Time‐domain application of superimposed quantities in the phase comparison transmission line protection scheme
Authors: Silva Leite Junior Eduardo Jorge , Lopes Felipe Vigolvino , Silva Kleber Melo
Published: July 2018

Here, the use of incremental currents in time‐domain phase comparison (PC) line protection schemes is evaluated. The incremental currents have been applied in modern high‐speed protection relays, showing to be suitable for protection functions based on time‐domain analysis. To carry out the proposed studies, the alternative transients programme was used to simulate a wide variety of fault scenarios in a 500 kV/60 Hz test power system, considering different fault features (distance, resistance, and inception angle), source‐to‐line impedance ratio values, and system loading conditions. In each case, the tripping times of the time‐domain PC protection when implemented using traditional phase currents, sequence currents, traditional incremental currents, and incremental replica currents are compared. The obtained results show the use of incremental currents improves the PC protection reliability, speeding up the protection operation times.
Fault location method for high‐voltage direct current transmission line using incident current travelling waves
Authors: Wang Bin , Yang Lin , Dong Xinzhou
Published: July 2018

The reflection coefficient of the travelling wave is different with different frequencies because of the inductance and capacitive elements on the boundary of the DC transmission line, which leads to the oscillation of the travelling wave. It is difficult to obtain the wave head's arrival time accurately using travelling wave method to locate fault because of the oscillation. The current travelling wave is the superposition of the incident current travelling wave and the reflected current travelling wave. There is no oscillation in the incident wave. Therefore, a method using incident current wave for fault location is proposed here. The initial current travelling wave and the transmission line boundary function are used to calculate the incident current travelling wave, and the incident wave is used to locate fault. The Prony decomposition algorithm is used to identify boundary function using the initial current travelling wave generated in specific fault condition. PSCAD simulation shows that the influence of oscillations of travelling wave can be eliminated by using incident current wave to locate faults, and the accuracy of fault location is improved.
Current‐restrained DC under‐voltage protection for a bipolar HVDC system
Authors: Kang Sang‐Hee , Hwang Chang‐Hyun
Published: July 2018

The proposed method in this study is a current‐restrained DC under‐voltage protection for a bipolar HVDC system. In a bipolar HVDC system, the inrush phenomenon of a converter transformer can cause the DC voltage drop of the operating pole due to the sympathetic inrush. In this case, the DC under‐voltage protection relay in a bipolar HVDC system may trip the operating pole. Then the bipolar HVDC system cannot transmit any power. In order to block the ignition of an unwanted trip when the converter transformer of the not‐operating pole is energised, a current‐restrained DC under‐voltage protection method for a bipolar HVDC system is suggested. In this method, a DC harmonic current‐restraining element is used to detect an inrush phenomenon. The second harmonic component and the fundamental frequency component in the DC‐side current are used as a factor to judge the inrush phenomenon in this method. In order to discuss the proposed method, a bipolar HVDC system is modelled with CIGRE HVDC benchmark model by using PSCAD/EMTDC.
Topology optimization of the multi-fasteners jointed structure considering fatigue constraints
Authors: Hou Jie , Zhu Jihong , Wang Jie , Zhang Weihong
Published: July 2018

This paper is to present an important issue of fatigue failure in the design of multi-fasteners jointed structure. To avoid failure in the connection area, Sines criterion is utilized. Fatigue constraints are handled in the context of stress based topology optimization. To eliminate the high stresses caused by the finite element modeling, the control volume is defined to evaluate the stress states around the fasteners. The standard topology optimization is extended to minimize the structural compliance with fatigue failure constraints. To address singularity problems related to stress constraints, q-p relaxation is used. P-norm is used as the constraints aggregation scheme. Basing on the above, the design sensitivity of fatigue constraints is derived and calculated. The proposed method is verified by a numerical example of an assembled I-beam. The comparisons of the numerical results have shown the effect of the fatigue constraint.
Predicting well-connected SEP events from observations of solar soft X-rays and near-relativistic electrons
Authors: Núñez Marlon
Published: July 2018

This paper studies the use of electron data from the Electron Proton Alpha Monitor (EPAM) on board the Advanced Composition Explorer (ACE) in the UMASEP (University of Málaga Solar particle Event Predictor) scheme [Núñez, Space Weather 9 (2011) S07003; Núñez, Space Weather 13 (2015)] for predicting well-connected >10 MeV Solar Energetic Proton (SEP) events. In this study, the identification of magnetic connection to a solar particle source is done by correlating Geostationary Operational Environmental Satellites (GOES) Soft X-Ray (SXR) fluxes with ACE EPAM electrons fluxes with energies of 0.175–0.375 MeV. The forecasting performance of this model, called Well-Connected Prediction with electrons (WCP-electrons), was evaluated for a 16-year period from November 2001 to October 2017. This performance is compared with that of the component of current real-time tool UMASEP-10, called here WCP-protons model, which predicts the same type of events by correlating GOES SXR with differential proton fluxes with energies of 9–500 MeV. For the aforementioned period, the WCP-electrons model obtained a Probability of Detection (POD) of 50.0%, a False Alarm Ratio (FAR) of 39% and an Average Warning Time (AWT) of 1 h 44 min. The WCP-protons model obtained a POD of 78.0%, a FAR of 22% and an AWT of 1 h 3 min. These results show that the use of ACE EPAM electron data in the UMASEP scheme obtained a better anticipation time (additional 41 min on average) but a lower performance in terms of POD and FAR. We also analyzed the use of a combined model, composed of WCP-electrons and WCP-protons, working in parallel (i.e. the combined model issues a forecast when any of the individual models emits a forecast). The combined model obtained the best POD (84%), and a FAR and AWT (34.4% and 1 h 34 min, respectively) which is in between those of the individual models.
BWS-Behandlung mit Faszientools – Beweglich in drei Stufen
Authors: Haertel Oliver , Savoy Wolfhard
Published: July 2018

Mithilfe von Faszientools und korrigierenden Übungen können Therapeuten ihren Patienten Maßnahmen an die Hand geben, die in drei Stufen die Beweglichkeit verbessern. Auf dem Markt sind Werkzeuge verschiedener Anbieter erhältlich, die sich durch Form, Härtegrad und Übungskonzept unterscheiden. Oliver Haertel und Wolfhard Savoy zeigen beispielhaft in Wort, Bild und Videoclip eine BWS-Behandlung.
Traumatische Geburtsverläufe: Erkennen und Vermeiden
Authors: Weidner Kerstin , Garthus-Niegel Susan , Junge-Hoffmeister Juliane
Published: July 2018

Insbesondere sexuelle aber auch körperliche oder emotionale Gewalterfahrungen in der Biografie oder Gegenwart stellen einen Hochrisikofaktor für pathologische Schwangerschafts- und Geburtsverläufe mit Entwicklung von Traumafolgestörungen nach der Geburt sowie eine erschwerte Mutter-Kind-Bindung dar. Eine Geburt kann aber auch primär traumatisch erlebt werden, ohne dass es vorher Traumaerfahrungen gab. Schwierige und traumatisch erlebte Geburtsverläufe beeinträchtigen auch Geburtshelfer. Der vorliegende Beitrag gibt einen Überblick über Prävalenz und Risikofaktoren einer traumatisch erlebten Geburt sowie Verläufe, Auswirkungen und Interventionsmöglichkeiten.
Unilateral Tuberothalamic Artery Ischemia Caused by Pituitary Apoplexy
Authors: Bettag Christoph , Strasilla Christoph , Steinbrecher Andreas , Gerlach Rüdiger
Published: July 2018

Background and Importance Pituitary apoplexy (PA) occasionally occurs in patients with pituitary adenoma and may cause severe functional deficits. Headache, pituitary insufficiency, visual impairment, and cranial nerve palsies are the most frequent symptoms in patients with PA. Secondary cerebral ischemia develops in only a limited number of PA patients. Two pathogenic mechanisms were previously proposed. One states that ischemia may be due to major vessel encasement or to vessel compression, as a result of extended tumor growth. The second states that cerebral vasospasm following PA may cause ischemia. We present another mechanism. After PA, a sudden increase in suprasellar tumor volume can lead to compression of perforating arteries causing hypoperfusion and subsequent focal ischemia of the thalamus, basal ganglia, and internal capsule.

Clinical Presentation We present the case of a 75-year-old woman who, after having PA, developed cerebral ischemia in the territory of the left anterior thalamus and internal capsule that is primarily supplied by the tuberothalamic artery. Computed tomography and magnetic resonance imaging are used to describe how mechanical compression of the tuberothalamic artery caused this rare phenomenon. The recent literature, vascular anatomy, and pathophysiologic aspects of PA are discussed.

Conclusion PA can lead to compression of perforating arteries, for example, the tuberothalamic artery supplying the thalamus or lenticulostriate region, and thus cause hypoperfusion and subsequent focal cerebral ischemia. This may occur when perforating cerebral arteries are affected and compressed by the sudden increase in tumor volume due to hemorrhage or tumor swelling.
Laparoscopic Repair of a Right Paraduodenal Hernia
Authors: Manipadam John , V. Lekha , Syamprasad Vamsi , H. Ramesh
Published: July 2018

Laparoscopic repair of a right paraduodenal hernia has been described sparingly in literature. We present an account of how we laparoscopically repaired a right paraduodenal hernia along with a review of the current literature as regards the various techniques that have been attempted. With the patient in supine position, and with umbilical camera port and three 5 mm ports, we mobilized the cecum and ascending colon up to the third part of the duodenum, thereby widening the neck of the hernia sac in the Waldeyer fossa. This method is ideal for the less severe incomplete rotation presenting with right paraduodenal hernia where there are no Ladd's bands and there is no requirement for fetalization of the bowel.
Seltene Ursache eines Perinatalen Postrenalen Nierenversagens mit Megalourethra
Authors: Nagel Christine , Wiewrodt Barbara , Wirth Clemens , Ohnheiser Gerd , Wirbelauer Johannes
Published: July 2018

Bei einem Frühgeborenen mit einer mutmaßlichen obstruktiven Uropathie wurde als Ursache eines perinatalen postrenalen Nierenversagens eine Megalourethra nachgewiesen. Die Megalourethra – als eine seltene Differentialdiagnose bei Urethraerweiterung – ist eine angeborene, primär jedoch nicht obstruktive Fehlbildung der penilen Gerüststrukturen mit Dilatation der Urethra. Daher wurde insgesamt von einer distalen Stenose mit konsekutiver Fehlentwicklung der penilen Gerüststrukturen und Aspekt einer Megalourethra ausgegangen. Die weitere Diagnostik umfasste Sonografien des Harntraktes, Miktionszystourethrografie und MAG3-Szintigrafie. Therapeutisch wurde initial eine symptomatische Therapie, wie suprapubische Harnableitung, und im Verlauf eine operative Versorgung (Bengt Johanson) durchgeführt.
Numerical study on ocean thermal energy conversion system
Authors: Li Dashu , Yue Juan , Zhang Li , Duan Xili
Published: July 2018

A thermodynamic model is developed for ocean thermal energy conversion (OTEC) systems. Considering the narrow temperature range in the evaporator, different system capacities were analyzed and compared in the sub-critical state with practical ocean thermal conditions. The results show that higher evaporation pressure will lead to less thermal load in the evaporator and the condenser and lower mass flow rates of working fluid. The thermal efficiency of different systems and the power generation for unit heat transfer area were found to be closely related to evaporation pressure, with a positive linear relationship. It was also found that increasing the capacity of the system can increase the thermal efficiency and its power generation for unit heat transfer area. This study provides useful insights into the design and equipment selection of OTEC systems.
Thermal management of low concentrated photovoltaic systems using extended surfaces in phase change materials
Authors: Sathe Tushar M. , Dhoble A. S.
Published: July 2018

The applicability of phase change materials (PCMs) for the thermal management of low concentrated photovoltaic systems is explored in the current research work. Extended surfaces on the back surface of the PCM container are proposed with its small portion extruded to the outside. PCM thicknesses of 80 mm, 100 mm, and 120 mm are investigated, and an 80 mm thick PCM system is considered as the base configuration. Systems with 2 fins, 3 fins, and 4 fins are analyzed with two different fin lengths of 30 mm and 40 mm inside the PCM enclosure. Two-dimensional transient numerical analysis has been carried out with ANSYS FLUENT using the enthalpy porosity method. The nonuniform melting behavior of PCMs due to natural convection inside the molten PCMs is considered during the analysis using a Boussinesq approximation. The result shows that the proposed 4 fin configuration enhances the melting time by 6000 s compared to the no fin system, reduces the average PCM temperature inside the container by 18%, and decreases the heater surface temperature by 16%.
New optical spectroscopy approach reveals electronic properties of doped gallium nitride
Authors: Larter Raima
Published: July 2018

Contactless electroreflectance measurements show that a zinc dopant in gallium nitride acts as an acceptor with energy significantly deeper within the band gap than the widely used Mg acceptor.
Environmental decisions and the work/life environment: a story of how the edge brought prioritisation to the fore
Authors: McDonald-Madden Eve
Published: July 2018

Finding your feet in the world of work/life balance is challenging. There are so many things to consider. Sometimes it feels like a disaster on all fronts. In reality we have to make trade-offs and prioritise between work and life but unfortunately doing this is not just common sense. Making good decisions hinges on a way of problem-solving steeped in decades of research in the fields of economics, applied mathematics, philosophy and psychology – known as decision analysis – an approach famously described as a formalisation of common sense for decision problems which are too complex for informal use of common sense. Examining environmental decisions through the lens of this approach is the focus of my groups’ research. In this reflective piece I share my struggle with the complex and dynamic trade-offs between work and family life, and outline the steps of decision analysis in this context drawing on parallels with my research in environmental decision-making.
The evolution of argument coding patterns in South American languages
Authors: Gildea Spike , Guillaume Antoine
Published: July 2018

This special issue of JHL reconstructs the diachrony of a number of innovations in the coding of argument structure, particularly in the domain of verbal indexation, in four Amazonian language families (Chapacuran, Sáliban, Tukanoan and Tupi). It is one result of an international workshop on “Diachronic Morphosyntax in South American Languages” held in Lyon (France) in 2015, with financial support from the Collegium de Lyon (Institute for Advanced Study) and the LabEx ASLAN of the Université de Lyon. The goal was to encourage methodologically innovative (and more rigorous) historical studies of morphosyntactic patterns in languages or language families of South America. The five papers that comprise this collection all demonstrate the viability of syntactic reconstruction, even in languages with little or no written history.
Historical change in reported speech constructions in the Chapacuran family
Authors: Birchall Joshua
Published: July 2018

The reported speech construction found in the Chapacuran language family of South America has undergone a number of changes in the individual languages, such that its uses extend beyond that of merely reporting speech. In many languages, it is used to express the inner states of the reported speaker, and in some cases it is used to express imperfectivity and causation. This paper argues that the future construction in Moré is a further development of the reported speech construction, one that has been reanalyzed as a basic main clause type. The morphosyntactic properties of the source construction explains the divergent inflectional forms, the loss of object indexation, and the innovation of an object case marker in the future construction. This paper provides new insights into the diachronic pathways that can lead to innovative future constructions as well as the origins of a tense-based split in case marking in Moré.
The Piaroa subject marking system and its diachrony
Authors: Rosés Labrada Jorge Emilio
Published: July 2018

Piaroa, a member of the Sáliban language family, is spoken on both sides of the Colombian-Venezuelan border. Based on unpublished fieldwork data for Mako and Piaroa and published Piaroa and Sáliba data, this article focuses on the Piaroa subject marking system and its origins. I show that the subject prefixes and inner suffixes used in future tense were inherited from Proto-Sáliban and must therefore have preceded the rise of the right-margin subject markers ‑sæ, -hæand ‑Ø. Based on comparative Mako data, I propose that these markers are old copular suffixes that entered the verbal domain through a nominal predication construction whose use expanded to encode habitual aspect. This research not only constitutes an important contribution to the description of Piaroa but also expands, within a Diachronic Construction Grammar approach, our understanding of complex systems of person marking, the origins of multiple exponence, and the role of multiple source constructions in paradigm creation.