bluuebunny/crossref_metadata_2025 huggingface dataset:
Raising the potential of a local market for the reactive power provision by electric vehicles in distribution grids
Authors: Sousa Tiago , Hashemi Seyedmostafa , Andersen Peter Bach
Published: April 2019

The promotion of electric vehicles (EVs), triggered by environmental concerns, can also increase the flexibility of power systems through ancillary services, such as frequency regulation among others. Nevertheless, EV penetration has increased the concern regarding voltage drops in distribution grids. This concern has motivated researchers to examine EV reactive power provision to mitigate such problems. This work proposes a local market perspective to promote EV reactive power provision, enabling distribution system operators to control the voltage level using cost‐effective solutions. The authors propose the extension of a centralised control framework that schedules EV frequency regulation to optimise the reactive power provided by the same EVs. Additionally, extra power losses in chargers while EVs provide reactive power were investigated, and the associated cost in the economic evaluations were considered. A test‐case with the IEEE 33‐node distribution grid is used to assess the market potential of EV reactive power provision. This new service extends EV penetration in a cost‐efficient way without causing voltage problems. The simulation concludes that it is economically feasible to use EVs for reactive local provision with efficient chargers. These outcomes sustain the potential of promoting such new EV services through a proper market in distribution grids.
Design and analysis of functional link artificial neural network controller for shunt compensation
Authors: Arora Ankita , Singh Alka
Published: April 2019

Here, a new control algorithm based on functional link artificial neural network (FLANN) has been designed and studied for shunt compensation. FLANN controller is synonymous to extended trigonometric functional non‐linear expansion and is trained online to achieve mitigation of different power quality (PQ) problems. Increased use of power electronics‐based loads has contributed to harmonic pollution in power distribution systems and the PQ issues raised need to be effectively addressed. Several other PQ problems exist at the load end such as poor power factor, unregulated voltage, load unbalancing etc. and these can be effectively controlled using a shunt compensator. The designed FLANN controller is based on individual non‐linear functional expansion of the input signal and it is updated online by the adaptive least mean square (LMS) corrective learning algorithm. The controller is designed to predict the weighted active component of load current to generate reference supply current for the grid. The algorithm converges fast and has good transient as well as steady‐state response. Simulation as well as experimental results are shown for shunt compensator installed for the single‐phase grid‐connected system and the performance results are compared with some conventional algorithms usually utilised for compensation.
Piecewise control strategy for electric spring
Authors: Yuan Chang , Feng Jiayao , Tong Ming , Yang Dan , Tang Niang
Published: April 2019

Electric spring (ES) as a device to solve the voltage fluctuation problem caused by the connection of a large number of renewable energy sources to the power grid has developed quickly. ES which involves a power inverter with a capacitor in DC side (ES‐C) with the simple structure and low cost has great potential for application with strict control requirements and some operation details are not been discussed. In this study, based on the analytical solution of ES‐C's operating points, the operation region of ES‐C is divided into four parts. Also, a piecewise control strategy was proposed to ensure the safe and stable operation of ES‐C. With the piecewise control, ES‐C can participate in system frequency regulation while maintaining load voltage as rated voltage. Also, the simulations in PSCAD/EMTDC proved that the proposed piecewise control can switch between operation regions and can make full use of the operating points of ES‐C.
Secure operating bounds for wind energy conversion systems working as conventional power generation plants
Authors: Lopez‐Garcia Irvin , Lopez‐Monsalvo Cesar S. , Beltran‐Carbajal Francisco , Escarela‐Perez Rafael , Olivares‐Galvan Juan C.
Published: April 2019

In this work, it is shown that it is possible to operate a wind energy conversion system (WECS) based on a doubly fed induction generator while operating in a different mode than maximum power tracking. Here, using the recent results on the steady state solution of the torque balance transcendental equation, analytical expressions for all the state variables of the WECS are obtained. In this fashion, closed‐form online reference trajectories for the system variables are presented. These analytical formulas can be used to perform power tracking control into the safe operational region of WECS. Moreover, realistic generic case studies are described to depict how these results are useful in systematically assessing the secure operating regime for both, the electric and mechanic components of the WECS.
Research on the deterioration process of electrical contact structure inside the ±500 kV converter transformer RIP bushings and its prediction strategy
Authors: Tian Huidong , Liu Peng , Zhou Shiyi , Wang Qingyu , Wu Zehua , Zhang Jinyin , Peng Zongren
Published: April 2019

Extra high‐voltage converter transformer resin impregnated paper (RIP) bushing is used as the outlet device of the converter transformer, its safe operation is directly related to the reliability of the power system. Under the long‐term effects of high current, strong mechanical stress and abrasion, the contact resistance of connection structure inside the bushing is prone to deteriorate. When the local overheating increases to a certain level, the insulation performance of bushing will decline and may lead to penetrating discharge. Therefore, it is vital to develop strategies for predicting the overheating fault of RIP bushings. In this study, firstly, one typical overheating fault of RIP bushing induced by the contact deterioration was diagnosed according to the fretting corrosive model and SF6 decomposition process. Secondly, using the three‐dimensional electromagnetic‐thermal‐fluid finite element method, the temperature distributions of RIP bushing under the different overheating degrees were simulated. Finally, based on the maintenance experience and simulation results, the diagnosis strategies were proposed. The diagnosis principle and prediction strategies were successfully helped to maintain the faulted RIP bushings and wall bushings before a destructive overheating accident could occur, which provide a basic reference for the fault prediction and improvements of relative standards.
Enhanced probabilistic approach for substation reliability assessment
Authors: Bagen Bagen , Huang Dange , Fattal Karim
Published: April 2019

A new enhanced probabilistic approach for substation reliability assessment is presented. The proposed technique evaluates substation reliability using a combinative approach that considers not only the impact of substation equipment failures but also the effect of the system conditions in which the substation resides. The approach uses the analytical contingency enumeration technique and uses a commercial program to perform power flow analysis in order to assure the accuracy of the reliability evaluations. The application of the proposed approach is illustrated by performing probabilistic reliability assessment on an actual utility substation. The technique presented will enable more realistic assessment of the reliability performance of substations and/or switching stations using probabilistic approaches.
Survey on the approaches based geometric information for 3D face landmarks detection
Authors: Manal El Rhazi , Arsalane Zarghili , Aicha Majda
Published: April 2019

Facial landmarks detection is an important and basic step in many face analysis applications. For this reason, it is considered a challenging task as the final results of the analysis depend on the accuracy of the landmarks detection. Decades of research have investigated approaches for two‐dimensional (2D) facial landmarks detection but; however, the good obtained results, they still suffer from some weakness regarding the pose and illumination variations. Recently, the large availability of 3D scans makes the use of 3D face models easier hence, overcome the problems caused using 2D images. Many papers have studied the problem of 3D facial landmarks detection; nevertheless, there is a lack of literature reviews allowing an overview of the studies and researches related to the 3D face landmarks detection. In this study, the authors present a detailed survey of the latest (2010–2018) approaches based geometric information for 3D face landmarks detection, including the limitations and strengths of each work.
OrthoMaps: an efficient convolutional neural network with orthogonal feature maps for tiny image classification
Authors: Moradi Reza , Berangi Reza , Minaei Behrooz
Published: April 2019

In image processing domain of deep learning, the big size and complexity of the visual data require a large number of learnable variables. Subsequently, the training process consumes enormous computation and memory resources. Based on residual modules, the authors developed a new model architecture that has a minimal number of parameters and layers that enabled us to classify tiny images using much less computation and memory costs. Also, the summation of correlations between pairs of feature maps as an additive penalty in the objective function was used. This technique encourages the kernels to be learned in a way that elicit uncorrelated representations from the input images. Also, employing Fractional pooling helped to have deeper networks that consequently resulted in more informative representation. Moreover, employing periodic learning rate curves, multiple machines are trained with a less total cost. In the training phase, a random augmentation to the input data that prevent the model from being overfitted was applied. Applying MNIST and CIFAR‐10 datasets to the proposed model resulted in the classification accuracy of 99.72 and 93.98, respectively.
Adversarial image generation by combining content and style
Authors: Liu Songyan , Zhao Chaoyang , Gao Yunze , Wang Jinqiao , Tang Ming
Published: April 2019

Images can be considered as the combination of two parts: the content and the style. The authors’ approach can leverage this property by extracting a certain unique style from the reference images and combining it to generate images with new contents. With a well‐defined style feature extraction module, they propose a novel framework to generate images with various styles and the same content. To train the style specific image generation model efficiently, a double‐cycle training strategy is proposed: they input two natural‐content pairs simultaneously, extract their style features, and exchange them twice to obtain the reconstruction of the input natural images. What is more, they apply the triplet margin loss to the style feature extracted from the images before and after style exchange and an adversarial discriminator to force the style‐exchanged images to be real. They perform experiments on licence‐plate image, Chinese characters, and shoes or handbags images generating, obtain photo‐realistic results and remarkably improve the corresponding supervised recognition task.
Modelling of crosstalk in differential through silicon vias for three‐dimensional integrated circuits
Authors: Pan Jin‐Wei , Fu Kai , Liu Qi , Zhao Wen‐Sheng , Dong Linxi , Wang Gaofeng
Published: April 2019

The crosstalk effects of differential through silicon vias (D‐TSVs) are studied. The equivalent circuit model is developed, with the circuit elements extracted analytically. Using the three‐dimensional (3D) full‐wave field solver HFSS, the circuit model is validated up to 100 GHz. By virtue of the circuit model, the noise couplings in the D‐TSVs are evaluated. It is found that the noise coupling can be cancelled in the D‐TSVs for a particular case. Finally, the influence of floating silicon substrate on the crosstalk in the D‐TSVs is investigated.
Low‐profile triple‐band microstrip antenna via sharing a single multi‐mode patch resonator
Authors: Liu Neng‐Wu , Chen Xin‐Peng , Zhu Lei , Chen Xi , Fu Guang , Liu Ying
Published: April 2019

A low‐profile microstrip patch antenna (MPA) operating in triple WLAN bands (2.4 /5.2 /5.8 GHz) with stable broadside radiation is proposed by employing TM10, TM12, and TM30 modes. Firstly, the TM12 mode of the MPA could be excited at around 5.8 GHz by properly selecting its dimensions. Meanwhile, a linear slot is etched out at the center of the radiating patch to transform the radiated fields of TM12 and TM30 modes into the broadside radiation with low sidelobe level. Secondly, the shorting pins are symmetrically loaded underneath the patch, aiming to improve the input impedance matching of TM10 mode and push up its resonant frequency to around 2.4 GHz. Thirdly, a pair of parallel slots is near the radiating edges of the patch radiator, thus extending the surface current distribution of TM30 mode and reallocating its resonant frequency to around 5.2 GHz. In final, the prototype antenna is fabricated and measured to validate its working principle. The results illustrate that this low‐profile MPA makes these three radiative modes resonate at around 2.44, 5.22, and 5.82 GHz, respectively. Most importantly, a stable normal radiation pattern with low cross‐polarisation and sidelobe levels is maintained for the proposed antenna as well.
Design and analysis of a millimetre‐wave high gain antenna
Authors: Erfani Elham , Safavi‐Naeini Safieddin , Tatu Serioja
Published: April 2019

A broadband and high gain transmit array (TA) antenna, operating at 60 GHz, is proposed. To meet the design requirements of a TA antenna with polarisation‐insensitive radiation performance, an optimal multi‐layer unit cell (UC) is introduced. The dimensions of the UC are parametrically expressed to realise a linear transmission phase response with a variation range of 270° and insertion loss <−3 dB over the desired frequency band ranging from 58 to 64 GHz. A new planar array composed of 2 × 4 aperture‐coupled‐patches interleaved with a soft‐surface is also designed as a feed for the proposed TA. Furthermore, a hybrid method based on full‐wave simulations and analytical formulations is developed to calculate the radiation characteristics of the TA antenna and the results are compared to the ones achieved with full‐wave simulations. The designed TA antenna is fabricated and the measurement results are presented. The obtained results show peak aperture efficiencies of 38.48% (30.85 dB peak gain) and 32.37% (30.1 dB peak gain), and −1 dB gain bandwidths of 7.7 and 8.2% from the full‐wave simulations and measurements, respectively. Such a broadband and high gain antenna is deemed to be suitable for mm‐wave backhaul links in 5G cellular systems.
Wearable and meshed wideband monopole antennas and their interactions with the human body
Authors: Rayner Phoebe , Zhang Shiyu , Cadman Darren , Vardaxoglou John (Yiannis) C. , Whittow Will
Published: April 2019

This study considers a wideband monopole antenna and its interactions with different separations from the human body phantom over a wide frequency. A meshed alternative version has also been developed which has similar performance to the circular wideband monopole antenna but requires less material. The specific absorption rate and efficiency of this antenna have been analysed as a function of separation distance and frequency. The mesh design has been fabricated by using embroidery and 3D printing techniques.
Quasi‐Cassegrain metasurface antenna with shielded vias and wide bandwidth
Authors: Gao Guoping , Yang Chen , Hu Bin , Wang Shaofei , Zhang Ruifeng
Published: April 2019

A novel quasi‐Cassegrain metasurfaces (MS) antenna with wide bandwidth operating in 8 GHz band is proposed. Initially, the article demonstrates a complete set of working principles and design approach for the proposed antenna. Then, this antenna is optimised, manufactured, and measured. The profile of the antenna is further reduced by using the reflect‐array based on MS, and the gain is improved by loading shielded vias. Note that the second resonant frequency generated from sub‐reflector is utilised to extend the bandwidth. The measured results indicate that the antenna achieves the peak gain of 15.9 dBi, impedance bandwidth of 1.07 GHz, and half power beam width of 26° in E plane and 21.5° in H plane. It has a low profile of 26.5 mm (0.71λ0) and occupies an area of 120 mm × 120 mm (3.20λ0 × 3.20λ0). The article not only completes the antenna operating in 8 GHz band but also provides a reference for the design of the proposed quasi‐Cassegrain antenna in microwave band.
Traffic model of machine‐type communication for railway signal equipment based on MMPP
Authors: Lin Junting , Hu Xueyang , Dang Jianwu , Wu Zhongqing
Published: April 2019

Machine‐to‐machine communication can realise considerably better information cognition of fixed and mobile equipment during rail transit. To assess the network access performance of the machine‐type communication (MTC) of railway signal equipment for next‐generation intelligent transportation system, the forecasting model of the machine communication traffic of railway signal equipment was divided into station indoor model, station outdoor model, and section movement model on the basis of cell units, and the traffic quantity and signaling overhead of the three models were calculated respectively. Based on Poisson's distribution and the Markov update process, an improved Markov‐modulated Poisson Process (IMMPP) of the source traffic model was designed. Compared with the 3GPP traffic model, the IMMPP model maintains a good balance between the complexity and the relatively high accuracy of the signal equipment in the station outdoor and section scenarios. The simulation experiments showed that the IMMPP consumed 0.44 s more than 3GPP model 2 in the section scenario and 1.99 s in the station outdoor scenario, and the simulation equipment was in accordance with the actual railway signal equipment. The research result can provide a reference for the description of MTC traffic of other specialised equipment in the railway environment.
Compact planar reconfigurable UWB‐MIMO antenna with on‐demand worldwide interoperability for microwave access/wireless local area network rejection
Authors: Mathur Rohit , Dwari Santanu
Published: April 2019

In this study, a compact ultrawideband (UWB) multiple‐input–multiple‐output (MIMO) antenna with reconfigurable band notch characteristics is presented. The key feature of the antenna is its novel dual‐band notch technique which blocks worldwide interoperability for microwave access or wireless local area network band interference. The UWB‐MIMO property is achieved by two square monopoles separated by grounded multi‐branch T‐shaped stub. The reconfigurable dual‐band notch operation is performed by PIN diodes integrated in a parasitic resonant structure in the ground plane. The antenna has a compact size of 40 × 20 mm2, with the operating frequency band of 3–11 GHz, where port isolation is better than 15 dB. The MIMO performance is ensured by calculating envelope correlation coefficient for the isotropic, indoor and outdoor environment.
1.1 THz tenth harmonic mixer based on planar GaAs Schottky diode
Authors: Zhang Bo , Lv Xiaolin , He Jie , Xing Dong , Fan Yong , Chen Xiaodong
Published: April 2019

Here, the tenth harmonic mixing technology based on planar GaAs Schottky diode is first proposed for the 1.1 terahertz (THz) frequency conversion module. The first higher order mode cut‐off frequency of the suspended microstrip line has been investigated to determine the appropriate cross‐sectional dimension of transmission line shield cavity in the radio frequency (RF) circuit portion. The height of shield cavity of transmission line is designed to be discontinuous in order to facilitate the assembly of the diode. A modelling approach combining field and circuit is used to achieve joint simulation of linear passive structure and diode non‐linear characteristics. The simulation results show that the frequency conversion loss of this mixer is <55 dB in the RF frequency range of 1.03–1.154 THz, and the best frequency conversion loss is 50 dB at RF of 1.098 THz.
Dual‐band circular polarisation generation technique with the miniaturisation of a rectangular dielectric resonator antenna
Authors: Gotra Shailza , Varshney Gaurav , Yaduvanshi Rajveer Singh , Pandey Vinay Shankar
Published: April 2019

A technique is proposed to obtain the dual‐band circularly polarised (CP) response along with the miniaturisation of a singly fed rectangular dielectric resonator (DR) antenna. The miniaturised response is obtained by applying the metallic strips on the sidewalls of the DR. The specific format of the applied metallic strips excites the orthogonal degenerate modes. Thus, a dual‐band CP response is obtained along with the miniaturisation of antenna. The proposed antenna is designed to obtain the small frequency ratio. The frequency ratio can also be tuned by changing the surface area of the applied metallic strips.
Multi‐step wind power forecast based on VMD‐LSTM
Authors: Han Li , Zhang Rongchang , Wang Xuesong , Bao Achun , Jing Huitian
Published: April 2019

To improve the accuracy of multi‐step wind power forecast, a variational mode decomposition‐long short‐term memory (VMD‐LSTM) forecast method is proposed. Firstly, the variational mode decomposition method is adopted to decompose the wind power data into three constituent modes, named as the long‐term component, the fluctuation component and the random component. Secondly, long short‐term memory network is utilised to deeply learn the characteristics of the three constituent modes. Profit from its unique forget gate and memory gate structure, the association with long‐term time series is learned to build a multi‐step forecast model. Finally, the wind power data from ELIA and NERL are used to test. The error analysis shows that the proposed method has superior performance in the multi‐step forecast and real‐time forecast.
Planning of HMG with high penetration of renewable energy sources
Authors: Baseer Muhammad , Mokryani Geev , Zubo Rana H. A. , Cox Steve
Published: April 2019

Hybrid AC–DC microgrid (HMG) allows direct integration of both AC distributed generators (DGs) and DC DGs, AC and DC loads into the grid. The AC and DC sources and loads are separated out and are connected to respective subgrid mainly to reduce the power conversion; thus the overall efficiency of the system increases. This study aims to introduce a novel HMG planning model within a microgrid market environment to maximise net social welfare (NSW). NSW is defined as the present value of total demand payment minus the present value of total planning cost, including the investment cost of distributed energy sources (DERs) and converters, operation cost of DERs, and the cost of energy exchange with the utility grid subject to network constraints. The scenario tree approach is used to model the uncertainties related to load demand, wind speed, and solar irradiation. The effectiveness of the proposed model is validated through the simulation studies on a 28‐bus real HMG.
Renewable energy: evaluation of low energy demand pre‐treatments to optimise methane production from microalgae
Authors: Zhang Yanghanzi , Caldwell Gary S. , Sallis Paul J.
Published: April 2019

Anaerobic digestion (AD) of microalgae is a sustainable process to produce methane‐rich biogas for bioenergy production. However, the rigid cell walls of microalgae protect them against the attack from hydrolytic bacteria, and consequently prevent efficient biodegradability and lower methane production. In this study, the effects of low energy demand enzymatic and low‐temperature thermo‐alkaline pre‐treatments on microalgae AD were investigated in batch biochemical methane potential tests. The results found that methane yields were significantly enhanced by both pre‐treatments. Microalgae Chlorella vulgaris (C. vulgaris) after enzymatic pre‐treatment enhanced methane yields the most, by 22–162%, whilst C. vulgaris pre‐treated by thermo‐alkaline pre‐treatment improved methane yields by 4–26%. In enzymatic pre‐treatment, C. vulgaris pre‐treated with mixed enzymes showed higher methane yields compared to single enzymes. In low‐temperature thermo‐alkaline pre‐treatment, the level of enhancement in methane yields depended on the alkaline dosage and pre‐treatment temperature, but the high alkaline dosages were associated with limitations such as a prolonged lag phase in the digestion process. From an energy viewpoint, both pre‐treatments showed positive energy balances for the majority of experimental conditions, and therefore both pre‐treatments are considered to be energetically efficient methods to pre‐treat microalgae for methane production via AD.
Simple and robust model predictive control of PMSM with moving horizon estimator for disturbance compensation
Authors: Toso Francesco , De Soricellis Milo , Bolognani Silverio
Published: April 2019

This paper deals with a novel robust current control scheme for PMSM drives, based on the model predictive control (MPC) theory. It has been designed a simple quadratic formulation of the reference tracking problem in order to compute the optimal commanded voltage. Considering only equality constraints allows the efficient computation of a closed‐form solution which solves the minimisation problem. Authors' proposed objective function is extended to include the inequality constraints, such as current and voltage limitations, therefore, the problem indirectly penalises the violation of boundaries through a weighting strategy. However, the controller does not require any calibration effort, maintaining the application suitable for different drive systems. The increased robustness is achieved through the integration of a moving horizon estimation (MHE), which exploits the same explicit formulation obtained for the MPC, but with the objective of estimating the voltage disturbance affecting the machine. The dual estimation problem is directly integrated within the prediction step of the MPC, improving drastically the local accuracy of the nominal model prediction with further advantages in terms of precise reference tracking and disturbance rejection capabilities. The effectiveness of the proposed control is verified by mean of test‐bed experiments.
Small power ZVS circuits for the marine‐controlled source electromagnetic transmitter
Authors: Song Hongxi , Zhang Yiming , Gao Junxia , Zhang Yu
Published: April 2019

Marine‐controlled source electromagnetic transmitter is an important equipment for the investigation of marine geology and exploration of oil, gas, and mineral resources in recent years. There are some problems from the direct current–direct current (DC–DC) converter of high power marine transmitter, the load is light, when the output current is relatively small, the lagging‐leg switching cannot easily achieve the zero voltage switching (ZVS), and the conversion efficiency of the heat converter requires improvement. This paper proposes a small power ZVS circuits for the marine‐controlled source electromagnetic transmitter (SPZVSC‐MCSET). The resonant inductance and blocking capacitor are appropriately used in the current‐ doubler‐rectifier converter, when in a wide load range the current‐ doubler‐rectifier converter can achieve ZVS. The Saber simulation and 100 W electromagnetic transmitter are used to verify the results.
Current derivative measurement using closed‐loop hall‐effect current sensor
Authors: Anuchin A. , Zharkov A. , Shpak D. , Aliamkin D. , Vagapov Y.
Published: April 2019

This paper discusses a method of the current derivative measurement using a standard closed‐loop Hall‐effect current sensor. The proposed method can operate with PWM‐driven inverters and provides the estimation of motor‐phase inductances required for an encoderless or self‐sensing control. The method is based on the current transformation feature of the closed‐loop sensor where a sensing inductor is connected in series with the measuring resistor. The voltage drop across the inductor is proportional to the current derivative. The experimental results are demonstrated that the measurement of the current derivative can be performed under a good accuracy, though the measurement should be executed while inverter is in the steady‐state condition.
Rapid sizing concept of interior permanent magnet machine for traction applications
Authors: Hoang Khoa Dang , Atallah Kais
Published: April 2019

This study presents a rapid sizing technique for interior permanent magnet (IPM) machine in traction application considering saturation effects. It is demonstrated that with limited computing resources, sizing, parameters considering saturation effects, and efficiency maps (loss maps) of an IPM machine can be generated within seconds with acceptable accuracy in comparison with finite element study and measurements. Thus, the proposed rapid sizing method is highly essential at the preliminary design stage of electric vehicle powertrains.
Utilisation of grain‐oriented electrical steel in permanent magnet fractional‐slot modular machines
Authors: Maraví‐Nieto Jaime , Azar Ziad , Thomas Arwyn S. , Zhu Zi‐Qiang
Published: April 2019

The performance improvement of using grain‐oriented electrical steels (GOES) in the stator of PM fractional‐slot modular machines is analysed in this study. Several models using a finite element tool are examined and it is concluded the techniques used in the actual software are not accurate for simulating anisotropic behaviour. Consequently, a simplified yet accurate modelling technique is proposed to simulate the performance of this type of electrical machines equipped with GOES. The advantages as well as the drawbacks of using GOES on the electromagnetic performance are investigated for different pole/slot combinations. It is concluded that the use of GOES is beneficial from an electromagnetic point of view mainly due to an increase on the radial component of the airgap flux density.
Smart management system for improving the reliability and availability of substations in smart grid with distributed generation
Authors: Refaat Shady S. , Mohamed Amira
Published: April 2019

Electrical power control and management is the key towards improving the efficiency and security of energy supply. Proper management would help in safely diversifying energy supplies, reducing energy consumption during peak load, and improving grid integration condition and reliability. Therefore, this study presents a novel real‐time and smart power management system for monitoring and controlling power flow between substations, distributed renewable sources, and loads towards optimising energy consumption and balancing electric power supply. The concept and architecture of the proposed system are discussed in this study within the context of the smart grid principle. The proposed energy management system does not require any changes in the traditional substation. Simulation results and implementation are conducted to demonstrate the validity of the proposed system.
Changes in Fe2+/Fe3+ molar ratio for the formation of spinel CoFe2O4 layered double hydroxide nanoparticles
Authors: Hamad Hesham , Ibrahim Amal , Abd El‐latif Mona
Published: April 2019

A facile, fast, and cheap method has been proved for large‐scale synthesis of super‐paramagnetic CoFe2O4 nanoparticles (CNPs) by the co‐precipitation process without surfactant and followed by calcination. In order to fabricate layered double hydroxide nanoparticles, the molar ratio Fe2+/Fe3+ should be changed and confirmed by transmission electron microscopy. Also, all synthesised CNP samples were characterised by X‐ray diffraction and vibrating sample magnetometer to investigate the relationship between the crystal size and the saturation magnetisation. The good correlation between the influence of Fe2+/Fe3+ ratio change and the initial pH showed that the slower formation of CNPs was obtained at higher concentration of NaOH and Fe3+. Also, the critical role for the crystal size, morphology, magnetisation characters, and cation distribution in the spinel structure was described well. Furthermore, the maximum saturation magnetisation and crystal size were obtained at the percentage Fe2+/Fe3+ (1:1). The results stated that the synthesised CNPs had the potential to become a promising material in large scale.
Activating ZnO nanorods photoanodes in visible light by CdS surface sensitiser
Authors: Biswas Indranil , Roy (Kundu) Piyali , Sinha Prasanta Kumar , Kanu Moumita , Chakraborty Ashim Kumar
Published: April 2019

Thin films of c ‐axis aligned uniform ZnO nanorods (NRs) were fabricated on to fluorine‐doped tin oxide‐coated soda lime glass substrate by a two‐step chemical route. Thereafter ZnO NRs/CdS core shell structures were successfully synthesised by depositing CdS layer on top of vertically aligned ZnO NRs using less hazardous nanocrystal layer deposition technique. The presence of CdS in ZnO NRs/CdS core shell structures was confirmed by energy dispersive X‐ray analysis. Examination of structure and morphology of the fabricated films by X‐ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) revealed that both films have one‐dimensional hexagonal wurtzite structure. Optical properties evaluated from ultraviolet–visible and photoluminescence spectra demonstrated better photo response of ZnO NRs/CdS core shell structure with respect to bare ZnO NR structure. Optical to chemical conversion efficiency of ZnO NRs/CdS photoanode was found to be ∼1.75 times higher than bare ZnO NRs photoanode in photo electrochemical water splitting under visible light.
Study on dynamic scaling of morphological evolution of TiO2 film deposited with different O2/Ar flow ratio
Authors: He Yanfei , Zhang Yi , Zhang Xin , Liu Yuanbing , Yang Xiaotian , Li Guozeng , Wang Hualin , Jiang Weiwei , Liu Chaoqian , Wang Nan , Liu Shimin , Cui Yunxian , Ding Wanyu
Published: April 2019

With increasing O2/Ar flow ratio from 2/18 to 20/0, TiO2 films were deposited by the direct current pulsed magnetron sputtering technique. The influence of O2/Ar flow ratio on plasma properties was discussed, which controlled the growth behaviour of TiO2 film. The growth behaviour influenced the value of roughness exponent α of TiO2 film, which reflected the dynamic scaling of the morphological evolution of TiO2 film. Finally, the relation between the dynamic scaling of the morphological evolution of TiO2 film and O2/Ar flow ratio was discussed systematically. The results indicate that with the other parameters constant, the growth behaviour of TiO2 film is dominated by O2/Ar flow ratio. By increasing O2/Ar flow ratio from 2/18 up to 6/14, the growth behaviour of TiO2 film transforms from the shadowing effect controlling to diffuse effect controlling, which results in the density of island structure on TiO2 film surface decreases, the size of island structure on TiO2 film surface increases, and the roughness exponent α of film decreases. When O2/Ar flow ratio exceeds 6/14, the density of island structure on TiO2 film surface remains constant. In this situation, the crystallographic orientation effect controls the growth behaviour of TiO2 film, which increases roughness exponent α.
Preparation of Fe3O4@C submicron rods for adsorption of methylene blue and fast separation from water
Authors: Sun Yue , Ni Peiyuan , Zhu Meiying , Yao Yonglin , Fu Shiwei
Published: April 2019

In this study, Fe3O4@C submicron rods were successfully prepared by an oxalate thermal decomposition–glucose hydrothermal carbonisation process. The adsorption property of the Fe3O4@C submicron rods to methylene blue was researched. The results show that the adsorption process conforms to the Langmuir isotherm model and pseudo‐second‐order kinetic model. The Fe3O4@C submicron rods show a comparable adsorption capacity compared with Fe3O4@C nanoparticles, but their separation speed under an external magnetic field is much faster than that of Fe3O4@C nanoparticles. These make the Fe3O4@C submicron rods an ideal material for the adsorption of the organic contaminant from water.
Reproductive allometry in four annual weeds
Authors: Guglielmini A. C. , Verdú A. M. C. , Satorre E. H.
Published: April 2019

Differences in plant biomass/plant seed production relationship imply that plants suppressed by competition to the same extent, may not suffer the same reduction in seed number setting. This size-dependent process evidenced by the quantitative relationship between plant growth and allocation to reproductive structures can be considered from an allometric perspective. The aim of this study was to describe the reproductive allometry of four annual weed species of the Pampas cropping systems by modelling the plant biomass/plant seed production relationship in Digitaria sanguinalis, Amaranthus hybridus, Setaria verticillata and Chenopodium album. To achieve this goal, two experiments developed during two consecutive growing periods (Experiments 1 and 2) were set up under greenhouse conditions. Weed species were grown in monocultures and in binary mixtures, with each other and with soybean crop, to obtain plants of different size after the effect of intra and interspecific competition. Data per plant regarding biomass versus seed number production considering monocultures and mixtures from Experiments 1 and 2 were analysed for each species using linear regression. Parameters of the linear functions fitted for C. album, S. verticillata and D. sanguinalis did not differ between experiments and data were pooled. Thus, three single specific models were obtained with the same intercept of zero (y-axis intercept when x = 0 was zero) and different slopes, 1122, 69 and 130 seeds g plant biomass–1 respectively. In the case of A. hybridus, the slopes were different in Experiments 1 (123 seeds g plant biomass–1) and 2 (74 seeds g plant biomass–1). Moreover, reproductive allocation changed allometrically under highly competitive stress since small plants failed to set seeds, unless a plant biomass threshold was attained (x-axis intercept when y = 0 was positive). Besides the ecological interpretation in reproductive output, implications in weed management are considered.
Macromolecular relaxation, strain, and extensibility determine elastocapillary thinning and extensional viscosity of polymer solutions
Authors: Dinic Jelena , Sharma Vivek
Published: April 2019

Significance

Macromolecules are often used as additives to modify flow behavior (rheology and processability) in myriad applications that involve drop formation or liquid transfer. However, processability is usually expressed in heuristic terms like jettability, printability, sprayability, spinnability, and so on and the influence of material properties is poorly understood and characterized. We utilize the recently developed dripping-onto-substrate rheometry to obtain fundamental and hitherto unreported insights into macromolecular properties (strain, relaxation, conformational transitions, and finite extensibility) that influence drop formation dynamics. We anticipate our findings will impact and inspire macromolecular engineering approaches for designing processing-friendly formulations.
The barcode, UMI, set format and BUStools
Authors: Melsted Páll , Ntranos Vasilis , Pachter Lior
Published: April 2019

We introduce the Barcode-UMI-Set format (BUS) for representing pseudoalignments of reads from single-cell RNA-seq experiments. The format can be used with all single-cell RNA-seq technologies, and we show that BUS files can be efficiently generated. BUStools is a suite of tools for working with BUS files and facilitates rapid quantification and analysis of single-cell RNA-seq data. The BUS format therefore makes possible the development of modular, technology-specific and robust workflows for single-cell RNA-seq analysis.

Availability and implementation

http://BUStools.github.io/ and http://pachterlab.github.io/kallisto/singlecell.html.

Supplementary information

Supplementary data are available at Bioinformatics online.
Endoscopic Resections in Inflammatory Bowel Disease: A Multicentre European Outcomes Study
Authors: Alkandari A , Thayalasekaran S , Bhandari M , Przybysz A , Bugajski M , Bassett P , Kandiah K , Subramaniam S , Galtieri P , Maselli R , Spychalski M , Hayee B , Haji A , Repici A , Kaminski M , Bhandari P
Published: April 2019

Background and Aims

Inflammatory bowel disease is associated with an increased risk of colorectal cancer, with estimates ranging 2–18%, depending on the duration of colitis. The management of neoplasia in colitis remains controversial. Current guidelines recommend endoscopic resection if the lesion is clearly visible with distinct margins. Colectomy is recommended if complete endoscopic resection is not guaranteed. We aimed to assess the outcomes of all neoplastic endoscopic resections in inflammatory bowel disease.

Methods

This was a multicentre retrospective cohort study of 119 lesions of visible dysplasia in 93 patients, resected endoscopically in inflammatory bowel disease.

Results

A total of 6/65 [9.2%] lesions <20 mm in size were treated by ESD [endoscopic submucosal dissection] compared with 59/65 [90.8%] lesions <20 mm treated by EMR [endoscopic mucosal resection]; 16/51 [31.4%] lesions >20 mm in size were treated by EMR vs 35/51 [68.6%] by ESD. Almost all patients [97%] without fibrosis were treated by EMR, and patients with fibrosis were treated by ESD [87%], p < 0.001. In all, 49/78 [63%] lesions treated by EMR were resected en-bloc and 27/41 [65.9%] of the ESD/KAR [knife-assisted resection] cases were resected en-bloc, compared with 15/41 [36.6%] resected piecemeal. Seven recurrences occurred in the cohort. Seven complications occurred in the cohort; six were managed endoscopically and one patient with a delayed perforation underwent surgery.

Conclusions

Larger lesions with fibrosis are best treated by ESD, whereas smaller lesions without fibrosis are best managed by EMR. Both EMR and ESD are feasible in the management of endoscopic resections in colitis.
Long-term Clinical Effectiveness of Ustekinumab in Patients with Crohn’s Disease Who Failed Biologic Therapies: A National Cohort Study
Authors: Liefferinckx Claire , Verstockt Bram , Gils Ann , Noman Maja , Van Kemseke Catherine , Macken Elisabeth , De Vos Martine , Van Moerkercke Wouter , Rahier Jean-Francois , Bossuyt Peter , Dutré Joris , Humblet Evelien , Staessen Dirk , Peeters Harald , Van Hootegem Philippe , Louis Edouard , Franchimont Denis , Baert Filip , Vermeire Séverine ,   Belgian Inflammatory Bowel Disease Research and Development Group [BIRD group]
Published: April 2019

Background

Ustekinumab [UST] was recently approved in Europe for the treatment of moderate to severe Crohn’s disease [CD]. Long-term real-world data are currently scarce for CD patients previously exposed to several biologics.

Methods

This is an observational, national, retrospective multicentre study. Patients received intravenous UST ~6 mg/kg at baseline, with 90 mg subcutaneously thereafter every 8 weeks. Response and remission rates were assessed at Weeks 8, 16, and 52.

Results

Data from 152 patients were analysed. All patients were exposed to at least one anti-TNFα agent, with 69.7% were exposed to even two anti-TNFα and vedolizumab. After 1 year, 42.1% and 25.7% of patients had experienced clinical response and clinical remission, respectively, and 38.8% and 24.3% had achieved steroid-free clinical response and remission, respectively; 38.8% of patients discontinued therapy during the 12 months of follow-up. Colonic location was predictive of clinical response at 1 year, and low body mass index [BMI] at baseline was a negative predictor of clinical remission. Resolution of arthralgia was associated with clinical response over time. De novo arthralgia was reported by 17.9% of patients at Week 8 and 13.5% of patients at Week 52. No impact of UST on arthralgia was observed in patients with concomitant ankylosing spondylitis [n = 17]. Others adverse events were reported in 7.2% of patients.

Conclusions

This real-world cohort study confirms the effectiveness of UST in CD patients previously exposed to several biologics. Ustekinumab was well tolerated with respect to adverse events.

Podcast

This article has an associated podcast which can be accessed at https://academic.oup.com/ecco-jcc/pages/podcast
Endovascular repair of thoraco-abdominal aortic aneurysms by fenestrated and branched endografts†
Authors: Gallitto Enrico , Faggioli Gianluca , Pini Rodolfo , Mascoli Chiara , Ancetti Stefano , Fenelli Cecilia , Stella Andrea , Gargiulo Mauro
Published: April 2019

OBJECTIVES

Our objective was to report the outcomes of fenestrated/branched endovascular aneurysm repair of thoraco-abdominal aortic aneurysms (TAAAs) with endografts.

METHODS

Between January 2010 and April 2018, patients with TAAAs, considered at high surgical risk for open surgery and treated by Cook-Zenith fenestrated/branched endovascular aneurysm repair, were prospectively enrolled and retrospectively analysed. The early end points were 30-day/hospital mortality rate, spinal cord ischaemia and 30-day cardiopulmonary and nephrological morbidity. Follow-up end points were survival, patency of target visceral vessels and freedom from reinterventions.

RESULTS

Eighty-eight patients (male: 77%; mean age: 73 ± 7 years; American Society of Anesthesiologists 3/4: 58/42%) were enrolled. Using Crawford’s classification, 43 (49%) were types I–III and 45 (51%) were type IV TAAAs. The mean aneurysm diameter was 65 ± 15 mm. Custom-made and off-the-shelf endografts were used in 60 (68%) and 28 (32%) cases, respectively. Five (6%) patients had a contained ruptured TAAA. The procedure was performed in multiple steps in 42 (48%) cases. There was 1 (1%) intraoperative death. Five (6%) patients suffered spinal cord ischaemia with permanent paraplegia in 3 (3%) cases. Postoperative cardiac and pulmonary complications occurred in 7 (8%) and 12 (14%) patients, respectively. Worsening of renal function (≥30% of baseline level) was detected in 11 (13%) cases, and 2 (2%) patients required haemodialysis. The 30-day and hospital mortality rates were 5% and 8%, respectively. The mean follow-up was 36 ± 22 months. Survival at 12, 24 and 36 months was 89%, 75% and 70%, respectively. The patency of target visceral vessels at 12, 24 and 36 months was 92%, 92% and 92%, respectively. Freedom from reinterventions at 12, 24 and 36 months was 85%, 85% and 83%, respectively.

CONCLUSIONS

The endovascular repair of TAAAs with fenestrated/branched endovascular aneurysm repair is feasible and effective with acceptable technical/clinical outcomes at early/midterm follow-up.