bluuebunny/crossref_metadata_2025 huggingface dataset:
Multi‐time‐scale robust economic dispatching method for the power system with clean energy
Authors: Zhu Jizhong , Liu Qiaobo , Xiong Xiaofu , Ouyang Jinxin , Xuan Peizheng , Xie Pingping , Zou Jin
Published: October 2018

Clean energies such as wind energy and solar energy have increased very fast in order to meet the environmental requirements. However, due to the uncertainties of wind and solar energy, the large‐scale integration of new energy presents a great challenge to the power system economic dispatch. Thus, a multi‐time‐scale robust economic dispatch strategy of a multi‐source hybrid power system based on the variable confidence level is proposed. The deterministic constraints of each time scale are transformed into robust constraints that take the uncertainty into account. Meanwhile, the robust level whose confidence level increases with the shortening of time scale is set to improve the scheduling conservative degree step by step. The selection principle of the robust level of each time scale is also presented. The proposed approach is applied to an IEEE 9‐bus system. The calculation results are compared with those from the traditional multi‐time scheduling method and show the effectiveness of the paper, which can reduce the uncertainty impact of wind, solar, and load forecast, as well as achieve a great balance of security, economic, and environmental benefits.
Diagnostic analysis and protective measures of transient ground potential rise in a 1000 kv UHV substation
Authors: Pang Fubin , Bu Qiangsheng , Liu Yu , Yuan Yubo
Published: October 2018

With the continuous expansion of power grid capacity and growth of voltage levels, the transient ground potential rise (GPR) caused by the switchgear operation has become great threaten to the safety of the grid. In the startup operation of 500 kV part of Taizhou 1000 kV ultra‐high voltage (UHV) substation, the electromagnetic lock installed in the switchgear filed was broken by the GPR in case of switchgear operation. There are two possible transmission paths of the GPR, one is the ground copper bar connecting the ground and the other is the control cable connecting the control cabinet and electromagnetic lock. In order to find out the transmission path of the electromagnetic disturbance, the experiment is carried out to distinguish the two possible paths. The waveform of the GPR in case of switchgear operation from different measuring points are recorded and compared, the results are analysed by comparing the signal characteristics and the transmission path is eventually diagnosed. Finally, the protective measures are proposed by wrapping the control wires with the conductive metal cube to reduce the influences of GPR. The outcomes in the study provide beneficial methods to analyse the GPR disturbance and positive guidance for the protection of locally installed equipment.
Coordination control strategy for three‐port SNOP based on FCS‐MPC
Authors: Peng Bo , Zhang Guorong
Published: October 2018

As a new type of power electronic device, Soft Normally Open Point (SNOP) can replace the traditional tie switch in distribution network to realise uninterrupted flexible regulation of power flow and optimise voltage profile. Several possible joining topologies and working modes of the three‐port SNOP in the distribution network is discussed here. For the back‐to‐back three‐port SNOP topology, a three‐port SNOP coordination control strategy based on Finite‐Control‐Set Model‐Predictive Control (FCS‐MPC) is proposed, which has many advantages of clear principle, simple implementation, and fast dynamic response. The dynamic mathematical model of three‐port SNOP is established, and the working mode set is proposed. Based on FCS‐MPC, the control algorithms of Udc Q mode, PQ mode, and CVCf mode are implemented. Accordingly, coordination control strategy between the modes of three ports is presented. In order to verify the feasibility of the proposed scheme, a three‐port back‐to‐back SNOP simulation model was built using Matlab/Simulink. The simulation results show that the proposed coordination control strategy can effectively achieve multi‐port coordinated control which can provide a flexible solution for applications of multi‐port SNOP.
Research for shielding effect of three‐phase air‐core reactors in substation by using different materials
Authors: Wenbiao Tao , Jinhao Wang , Zhenguo Ma , Weinan Duan , Wei Wang
Published: October 2018

To research the magnetic field interference on cables nearby three‐phase air‐core reactors and the shielding effect of different materials, this study analysed the influence on spatial magnetic field by using high‐conductivity materials and high permeability materials after the basis of three‐dimensional electromagnetic simulation model, and analysed the causes. Furthermore, the induced voltage in different shielding methods is calculated and discussed by using magnetic vector potential resulted from the finite element method. From the result, to achieve a satisfying effect, the shields under three‐phase reactors need connect when using high permeability. Moreover, a large number of magnetic leakages on the edge of shield can aggravate the magnetic field interference in surrounding areas. Therefore, the distribution of onsite cables in substation need to be considerate when using high permeability.
Coordination control of medium‐voltage hybrid ac/dc distribution
Authors: Xu Yini , Zhai Zhangliang , Kang Xiaoning , Guo Mingda , Ma Xiuda
Published: October 2018

Hybrid ac/dc distribution has attracted much attention recently. This study presents a medium‐voltage (MV) hybrid ac/dc distribution consisting of various distributed generations connecting to the ac and dc loads. Coordination control in hybrid ac/dc distribution is a challenging issue to achieve stability especially when there is a load rejection or loss of the generation. A new decentralised control is proposed to coordinate the hybrid ac/dc distribution even when the inter‐station telecommunication is not available. A new control is employed at interlinking converter (ILC) to maintain the power balance between ac and dc subgrids, and to ensure that the power quality is maintained in normal operating condition as well as in an extreme abnormal condition such as island mode. Further, a new control strategy is developed in battery storage system (BES) as a backup device to minimise the power fluctuation in the event of the shedding of the loads or generations. Another advantage of the combination of ILC and BES controllers is to provide a multiple slack terminals in both ac and dc grids, which will enhance the stability in the system. Simulation results have shown that the stability performance can be achieved in various operating scenarios.
FPGA implementation of impedance‐compensated phase‐locked loop for HVDC converters
Authors: Yi Yue , Ajinai Ajinai , Gole Aniruddha M..
Published: October 2018

The phase‐locked loop (PLL) plays a key role in HVDC systems. Recently, a new type of PLL called the impedance‐compensated phase‐locked loop (IC‐PLL) was introduced to compensate for the voltage drop across the AC network's Thevenin impedance, making the phase locking more robust against transients and harmonics. The IC‐PLL has an improved dynamic response as compared with the traditional approaches. However, earlier studies on the IC‐PLL are mainly based on off‐line simulations. In this study, an actual IC‐PLL is constructed in hardware and its performance is investigated by connecting it to a real‐time model of a line‐commutated converter‐based HVDC system on a real‐time digital simulator. The proposed IC‐PLL is constructed using a field‐programmable gate array platform. Paralleled and pipelined structures are implemented on the FPGA to achieve low latency and high speed. The performance of the IC‐PLL is tested by exposing it to different type of system disturbances such as sudden step change in power, voltage magnitude change and voltage distortion. Results are compared with the traditional trans‐vector PLL. The results show the performance of the IC‐PLL is superior.
Influence of moment of inertia on electric power system security and stability control
Authors: Ma Xiaguang , Yu Dahai , Nian Ming , Xu Zhenhua
Published: October 2018

The moment of inertia is the basic parameter of the generator and also the basic data of PSS parameter tuning. The parameter setting of PSS will increase the damping of the unit and improve the small disturbance stability of the system. When the rotational inertia parameter is not consistent with the real rotational inertia of the unit, the PSS parameter setting will not increase the damping of the unit, but sometimes it will cause the oscillation of the unit. Here, the correlation analysis is carried out with the small signal stability analysis program, and the field test is carried out in Qinghai Kang Yang power plant. The influence of moment of inertia on PSS is analysed by small disturbance analysis and field test.
Optimal control strategy of load aggregators with demand response
Authors: Zhou Xiao , Shi Jing , Li Shujian
Published: October 2018

This study presents an optimal control strategy for a load aggregator (LA) with demand response. The LA can provide consumers with time‐of‐use electricity price which could be different with the selling price of electricity by power grid. At the same time, LA has some distributed photovoltaic power generations, several diesel generators and energy storage devices to ensure user reliability and improve benefits. The LA's objective is to maximum its benefits without infringing the interests of consumers. A model of quadratical constraint quadratic programming is established to describe the above issues, and the generator‐battery control strategy with demand response (DR) under optimal economic operation of the system is solved by CPLEX. The results show that the proposed management strategy and DR strategy improves the operational economy of the system.
Research on the design principle of the contact terminal in large DC current loop of ±800 kV, 10,000 MW UHVDC converter station
Authors: Chen Peng , Lu Dongsheng , Ma Liang
Published: October 2018

The abnormal heating phenomena of contact terminal in large DC current loop of the ultra‐high voltage direct current (UHVDC) converter station became one of the most serious problems, which caused serious impact on the operation reliability of the power grid. Based on existing codes and standards of contact terminal temperature rise and the results of large current temperature rise test, the design principle of the contact terminal in large DC current loop of DC voltage ±800 kV, capacity 10,000 MW converter station is put forward and introduced detailedly in this study. Then, taking the design of three typical contact terminals in large DC current loop of Taizhou ±800 kV converter station as an example, the infrared temperature measurement results of contact terminals on the large current operation condition are analysed. The infrared temperature measurement results indicate that the design principle of the contact terminal in large DC current loop proposed in this study is able to meet the requirements of existing codes and standards of the temperature (temperature rise) limit of the contact terminal. This design principle is significant to improve the maintenance ability and operation reliability of the UHVDC converter station.
Multi‐layer power system tearing methodology for EMT‐TS hybrid parallel simulation
Authors: Mu Qing , Zhang Xing , Gong Chunming , Chen Yu
Published: October 2018

Due to the fast development of UHVDC, the power transferring through HVDCs takes a great part of the power from West China to East China. The response for multiple‐coupled HVDCs can only be simulated through EMT programmes. To increase the simulation accuracy, the EMT‐TS Hybrid simulation has been used in studies of the power system operation. Currently, the EMT‐TS hybrid simulation speed is too slow to be unaffordable. This paper presents a novel power system tearing technology to greatly improve the simulation speed in EMT‐ST Hybrid Simulation. The TS network is teared according to obtain network islands as many as possible, while the EMT network is teared through the combined transmission line and electric nodes. An algorithm is supposed to form the EMT‐ST sub‐network groups, which has no coupling with each other. Then, a novel parallel programme structure is proposed to use this EMT‐ST sub‐network groups to realise the parallel simulation and speedup the simulation. The case studies of the grids with seven HVDCs and 3000 nodes show that the proposed method could greatly improve the simulation speed without lowering precision.
Motor‐generator pair: novel technology to transmit stable and high‐quality power for power system with high penetration of renewable energy
Authors: Zhang Xin , Hang Yongzhang
Published: October 2018

With the increasing penetration renewable energy, some changes are transforming the power system dynamic characteristics, resulting in new stability issues. One of the issues is the lack of inertia and damping. One is sub‐synchronous oscillation (SSO) caused by inter‐harmonics associated with inverter‐based renewable power generators (IPRG). A novel technology is proposed to transmit stable and high‐quality power for power system with high penetration of renewable energy. Thus, the object of this paper is synchronous motor‐generator pair (MGP) system, a new gird‐connection device, which is proposed to solve above problems. First, the two mass block shaft model of MGP is established, which verifies the small signal stability of this system, and it has high damping that can be controlled flexibly. Then, the harmonic response of MGP is analysed through the internal electromagnetic relationship. Result shows that comparing with the input power from renewable energy sources to M side, the harmonic content of output power on G side is greatly reduced, especially the even harmonic. These characteristics are verified by experiments. So transmitted by MGP, the power quality and stability are greatly improved.
Small‐signal stability analysis for the multi‐terminal VSC MVDC distribution network; a review
Authors: Simiyu Patrobers , Xin Ai , Bitew Girmaw T. , Shahzad Muhammad , Kunyu Wang , Kamunyu Peter M.
Published: October 2018

The stable operation and control of the proposed terrestrial multi‐terminal Voltage Source Converter (VSC) medium voltage DC (MVDC) distribution network is a remarkable motivation towards developing the future universal DC grid interconnecting the low voltage DC systems on one side and the high voltage DC systems on the other. The small‐signal stability analysis are important in designing these power electronic based systems (PEBS). In this study, small‐signal stability approaches for PEBS are reviewed with the aim of identifying suitable methods for the proposed MVDC distribution network. It is established that the impedance‐based methods are suitable for local stability analysis complementing very well with the state‐space modelling‐eigenvalue analysis method best for global stability analysis. The Lyapunov linearisation method offers simple, adaptable, and accurate small‐signal and large‐signal stability study. On the other hand, the bifurcation analysis is an emerging non‐linear approach with promising efficiency and precision. In conclusion, there is no single small‐signal stability criterion that encompass an acceptable level of accuracy, adaptability, and efficiency. Thus, the impedance‐based methods combined with state‐space modelling‐eigenvalue analysis, Lyapunov linearisation, and bifurcation theory can be suitable small‐signal stability approaches for the multi‐terminal MVDC distribution network.
Influence of temperature on the growth characteristics of water tree in XLPE cable
Authors: Wenbiao Tao , Shuyong Song , Wei Zhang , Rui Bai , Weinan Duan , Wei Wang
Published: October 2018

In order to understand the characteristic of water tree growth for cross‐linked polyethylene (XLPE) at different temperatures, here, a new possible explanation is presented for the different characteristic at different temperatures. Water tree aging experiments were performed, respectively, at 0, 20, 40, and 60°C. The shapes of water trees were observed by an optical microscope, and the sizes of water trees at different temperatures were recorded. Based on the molecular dynamics and polymer orientation, the new possible explanation for the characteristics of water tree growth is proposed at high or low temperatures. According to the experiments, the rate of water tree growth first decreases and then increases with the rise of temperature and the transition temperature is about 40°C. The behaviours of thermal motion and orientation of molecules can both influence the water tree growth. The water tree growth at high temperature is mainly determined by the thermal motion, while the water tree growth at low‐temperature is mainly affected by the behaviour of molecules orientation.
Inrush current method of transformer based on wavelet packet and neural network
Authors: Wang Wei , Yan Lin , Jin Tao , Liu Hong , Hu Fan , Wu Dongxun
Published: October 2018

The transformer is an important equipment of power system; its operation state is directly related to the security and stability of the power system. Aiming at the problem that the differential protection of power transformer has been plagued by inrush current, a recognition method based on wavelet packet and the neural network is proposed. The inrush current and fault current signal are decomposed and reconstructed by using wavelet packet to extract wavelet packet reconstruction coefficients and calculate the energy of each band. These feature vectors are chosen as input values for the neural network. It has been shown by experiments that the inrush current and internal fault current can be accurately identified and the identification method can meet the requirement of the transformer inrush current real‐time identification system.
Research on segmented control of motor operating mechanism for high‐voltage circuit breaker
Authors: Feng Ying , Wan Haiyong , Wu Jianwen , Lan Jian , Deng Yun
Published: October 2018

To improve dynamic characteristics of the motor operating mechanism for high‐voltage circuit breaker, the motor drive operating mechanism by a three‐phase permanent‐magnet synchronous motor is studied in this article. After analysing the movement characteristics of the moving contact during the switching process, the movement process is divided into three stages: the starting stage, the constant speed stage, and the buffering stage. Considering the problems of the motor such as large start delay, instability, and strong buffeting in later stage with traditional fixed given displacement strategy, a new control strategy of given segmented displacement is proposed and studied on the simulation platform. The experiment results show that the design of the segmented control is reasonable and effective, not only can improve the dynamic characteristics of the motor, but also can implement the project more easily. So, it provides a theoretical basis for exploring the efficient dynamic control method of the new motor operating mechanism.
A direction element using high frequency transient energy in distribution network with distributed generation
Authors: Tao Ran , Song Guo‐bing , Yang Li‐ming , Zhang Chen‐hao , Han Wei , Shi Guang , Liu Chao
Published: October 2018

The accessing of distributed generation resources to distribution network leads to a multi power grid structure. The direction of power flow changes with it. The photovoltaic (PV) generation contains a large number of power electronic devices and control links, which causes that the output responses and fault characteristics are significantly different from the synchronous machine. In consideration of the topological structure of the distributed distribution network, this paper analyses the differences of transient characteristics of AC distribution line with PV power supply between internal and external faults. Then, a new principle for constructing directional element using transfer and consumption characteristics of high‐frequency transient energy is proposed. This directional element only uses high‐frequency transient fault voltage and current in early stage, which can reliably distinguish the fault direction. What's more, the existence of transition resistance will be conducive to the judgement. Finally, corresponding simulation cases were carried out to verify the feasibility and superiority of the proposed directional element.
VBR electromagnetic transient fast simulation model of synchronous machine based on time scale transformation
Authors: Shu‐Jun Yao , Peng Zhan , Shuo Zhang , Wan‐Hua Guo
Published: October 2018

In a large‐scale power system, electromagnetic transient simulation is facing the contradiction between simulation speed and simulation accuracy, so the electromagnetic transient models of the components in the power system have been continually being improved. The synchronous generator is an important part of the power system, and the Voltage Behind Reactance (VBR) model of the synchronous machine is deduced and improved on the basis of the classical model. The method of Single‐phase rotation transformation is based on the idea of a rotating coordinate system, and the frequency of the signal can be reduced by the rotation transformation. Moreover, the simulation step length of the electromagnetic transient is related to the frequency of the change of the electric quantity. The lower the change frequency is, the larger the simulation step can be. Here, according to the theory of single‐phase rotation transformation, the VBR model of synchronous generator based on time scale transform is deduced, which can simulate in the case of large steps without the loss of the precision, and thereby which the speed of electromagnetic transient simulation of power system will be effectively improved.
Exploration of FPGA‐based electromagnetic transient real‐time simulation system design using high‐level synthesis
Authors: Li Qiao , Xiang Yinxing , Mu Qing , Zhang Xing , Li Xiongfei , He Guanghui
Published: October 2018

Field‐programmable gate array (FPGA)‐based simulation system is applied in real‐time electromagnetic transient (EMT) simulation for small time‐step simulation. However, the FPGA‐based simulation system requires handcrafted hardware description language (HDL) and significant design efforts. This paper explores FPGA‐based EMT real‐time simulation system design using high‐level synthesis (HLS) technology to accelerate the design process and improve the flexibility, because high‐level language can be transferred into HDL using HLS. Furthermore, loop unroll and pipeline optimisation directives are analysed and applied for HLS to improve the computation speed of the components. The system can simulate various components, including switches, R‐L‐C, voltage sources, current sources, and transmission lines. Especially, the system adopting double‐precision floating‐point calculation can support the network with 74 nodes and achieve 2 us for each small time step on Xilinx Virtex7‐690 T FPGA. Comparison of simulation results from offline simulation tools with those from the proposed simulation system validates the correctness of the FPGA‐based EMT simulation system using HLS technology.
Unit commitment using improved adjustable robust optimisation for large‐scale new energy power stations
Authors: Xiu Lian‐cheng , Kang Zhi‐liang , Huang Peng
Published: October 2018

In order to minimise the electricity costs of the power system, this paper proposes an optimal operation scheduling for large‐scale new energy power stations with the uncertainty of wind and light power. The proposed scheduling method provides the optimal unit commitment and the economic operation, and it not only considers the generating costs of new energy power stations and thermal power plant but also considers switch machine cost of conventional thermal generating unit. The unit commitment of wind and light integrated power systems has a numerous of non‐linear characteristics, so the uncertainties require algorithm that can handle large amounts of robustness. Adjustable Robust Optimisation (ARO) can handle the uncertainty very well and is determined to be the main optimisation. At the same time, Particle Swarm Optimisation Algorithm (PSOA) is used to speed up the convergence. In summary, PSOA and ARO combination scheduling is demonstrated by the standard IEEE 10‐generator 39‐bus system. The improved ARO of simulation results prove that the conclusion of this paper is correct.
Investigation of the crosswind effect on the performance of the atmospheric air purification tower
Authors: Zhu Xincai , Wang Yingjia , Zou Zheng , Gong Hengxiang , Liu Zhuang , Yan Wen
Published: October 2018

To handle the increasingly serious air pollution issue, the concept of atmospheric air purification tower already has been proposed. The first prototype of such a novel system had been built in Xi'an, China. The aim of this study is to numerically study how the crosswind affects the dust removal performance of the atmospheric air purification tower and which counter‐wind strategy is optimal choice. To achieve that, a three‐dimensional model considering the external environment was developed in ANSYS Fluent. With the help of the proposed model, the benefits of three wind breaking designs were quantified and compared. The results showed that the design with inner union‐jack shaped wind break walls is the optimal for the atmospheric air purification tower. It can maintain the dust removal rate of the system at relatively high level (3.5 kg/h) no matter what crosswind intensity is.
Mesh stiffness calculation of helical gears with profile modification
Authors: Wang Yu , Shao Yimin , Chen Zaigang , Du Minggang , Xiao Huifang
Published: October 2018

Time‐varying contact line and mesh stiffness are important parameters for dynamic investigation of helical gear pair with profile modification; however, the calculation methods of the time‐varying mesh with high accuracy and high efficiency are also very limited currently. A new mesh stiffness calculation method for helical gear pairs with profile modification is proposed. The new method is conducted by cutting the helical gear tooth into slices to obtain the change of the contact line and the time‐varying mesh stiffness with considering the change of each slice's engagement performance introduced by the profile modification. Then, the mesh stiffness of the assumed three different modification cases is calculated by using the proposed method. The calculated results indicate that the proposed method can be used to calculate the mesh stiffness of helical gear pairs, especially of those with tooth profile modification.
Fast feature matching based on r ‐nearest k ‐means searching
Authors: Wang Ke , Zhu Ningyu , Cheng Yao , Li Ruifeng , Zhou Tianxiang , Long Xuexiong
Published: October 2018

Feature matching has been frequently applied in computer vision and pattern recognition. In this paper, the authors propose a fast feature matching algorithm for vector‐based feature. Their algorithm searches r ‐nearest neighborhood clusters for the query point after a k ‐means clustering, which shows higher efficiency in three aspects. First, it does not reformat the data into a complex tree, so it shortens the construction time twice. Second, their algorithm adopts the r ‐nearest searching strategy to increase the probability to contain the exact nearest neighbor (NN) and take this NN as the global one, which can accelerate the searching speed by 170 times. Third, they set up a matching rule with a variant distance threshold to eliminate wrong matches. Their algorithm has been tested on large SIFT databases with different scales and compared with two widely applied algorithms, priority search km‐tree and random kd‐tree. The results show that their algorithm outperforms both algorithms in terms of speed up over linear search, and consumes less time than km‐tree. Finally, they carry out the CFI test based on ISKLRS database using their algorithm. The test results show that their algorithm can greatly improve the recognition speed without affecting the recognition rate.
ALMA CO(2-1) observations in the XUV disk of M83
Authors: Bicalho Isadora C. , Combes Francoise , Rubio Monica , Verdugo Celia , Salome Philippe
Published: October 2018

The extended ultraviolet (XUV) disk galaxies are some of the most interesting objects studied in the last few years. The UV emission, revealed by GALEX, extends well beyond the optical disk after the drop in Hα emission, the usual tracer of star formation. This shows that sporadic star formation can occur in a large fraction of the HI disk at radii up to 3 or 4 times the optical radius. In most galaxies, these regions are poor in stars and are dominated by under-recycled gas; they therefore bear some similarity to the early stages of spiral galaxies and high-redshift galaxies. One remarkable example is M83, a nearby galaxy with an extended UV disk reaching 2 times the optical radius. It offers the opportunity to search for molecular gas and to characterize the star formation in outer disk regions, traced by the UV emission. We obtained CO(2-1) observations with ALMA of a small region in a 1.5′ × 3′ rectangle located at rgal = 7.85′ over a bright UV region of M83. There is no CO detection, in spite of the abundance of HI gas, and the presence of young stars traced by their HII regions. Our spatial resolution (17 pc × 13 pc) was perfectly fitted to detect giant molecular clouds (GMC), but none were detected. The corresponding upper limits occur in a region of the Kennicutt–Schmidt diagram where dense molecular clouds are expected. Stacking our data over HI-rich regions, using the observed HI velocity, we obtain a tentative detection corresponding to a H2-to-HI mass ratio of < 3 × 10−2. A possible explanation is that the expected molecular clouds are CO-dark because of the strong UV radiation field. This field preferentially dissociates CO with respect to H2, due to the small size of the star-forming clumps in the outer regions of galaxies.
Limits on stable iron in Type Ia supernovae from near-infrared spectroscopy
Authors: Flörs A. , Spyromilio J. , Maguire K. , Taubenberger S. , Kerzendorf W. E. , Dhawan S.
Published: October 2018

We obtained optical and near infrared spectra of Type Ia supernovae (SNe Ia) at epochs ranging from 224 to 496 days after the explosion. The spectra show emission lines from forbidden transitions of singly ionised iron and cobalt atoms. We used non-local thermodynamic equilibrium (NLTE) modelling of the first and second ionisation stages of iron, nickel, and cobalt to fit the spectra using a sampling algorithm allowing us to probe a broad parameter space. We derive velocity shifts, line widths, and abundance ratios for iron and cobalt. The measured line widths and velocity shifts of the singly ionised ions suggest a shared emitting region. Our data are fully compatible with radioactive 56Ni decay as the origin for cobalt and iron. We compare the measured abundance ratios of iron and cobalt to theoretical predictions of various SN Ia explosion models. These models include, in addition to 56Ni, different amounts of 57Ni and stable 54,56Fe. We can exclude models that produced only 54,56Fe or only 57Ni in addition to 56Ni. If we consider a model that has 56Ni, 57Ni, and 54,56Fe then our data imply that these ratios are 54,56Fe / 56Ni = 0.272 ± 0.086 and 57Ni / 56Ni = 0.032 ± 0.011.
Choosing floating macrophytes for ecological intensification of small-scale fish farming in tropical areas: a methodological approach
Authors: Slembrouck Jacques , Samsudin Reza , Pantjara Brata , Sihabuddin Ahmad , Legendre Marc , Caruso Domenico
Published: October 2018

Several ecological services and functions are attributed to macrophytes, which may represent valuable resource for the ecological intensification of tropical fish farming. However, considering the multiple potential eco-services provided by macrophytes, the choice of the most appropriate species requires multiple criteria to assess these eco-services. Five floating macrophytes (Eichhornia crassipes, Lemna minor, Azolla filiculoides, Salvinia molesta and Salvinia spp.) were selected for this study. The six eco-services parameters compared among these macrophytes were: productivity (in % of seeded macrophytes), risk of non-productive cycles, nutritional value, impact on water quality, palatability (expressed as the percentage of plant ingested in 4 h) and ease of use. Experiments to determine these indicators were carried out in simple devices (net cages and plastic tanks) partially immerged in earthen ponds. The palatability of fresh macrophytes (whole or chopped) was studied in ponds using Osphronemus goramy juveniles. All indicators were scored from 1 to 5, and the highest score was assigned to the highest performer. These scores corresponded either to the evaluation of a single parameter (e.g. productivity) or to the average from scores of several parameters (e.g. nutritional score). Multiplier coefficients were applied for nutritional value and palatability. Azolla filiculoides showed the best scores for productivity; L. minor for nutritional value and palatability, and E. crassipes for the lowest risk of non-productive cycles and a positive impact on water quality. After integrating the scores in a multi-parameter matrix, A. filiculoides had the best overall score. The results of this approach to select macrophytes are discussed in light of the eco-services provided by macrophytes which may, in turn, promote the ecological intensification of tropical small-scale aquaculture.
An Adaptive Robust Controller for a Mobile Robot Driven by Mecanum Wheels
Authors: Wang Mingming , Zhu Yingying , Zhang Lei , Wang Lu , Wei Xuanbo , Fang Jing
Published: October 2018

An adaptive sliding mode controller was designed for a mobile robot driven by four mecanum wheels.The original contribution of this paper is employing adaptive robust controller to mecanum wheels driven mobile robot for obtaining better tracking and robustness performance.To complete the design of the controller, the kinematic model of the mobile robot driven by mecanum wheels was firstly proposed.An adaptive robust controller was designed subsequently.A sliding surface was designed in Proportional-Differential-Integral form, which satisfied the robustness requirements of the system.Besides, a reaching law which has quick convergence was introduced, which reduced the time consumed by the setting parameters and resisting external disturbance.The controller was demonstrated in the presence of impulsive disturbance and sinusoidal signal disturbance, which proved the superiority of the proposed controller.Finally, an experimental verification of trajectory tracking was implemented to verify the practicability and effectiveness.
Thread Modification Method for Load Balance on Planetary Roller Screw Mechanism
Authors: Guo Hui , Tong Ruiting , Liu Geng , Zhang Wenjie , Ma Shangjun
Published: October 2018

Based on the relationship between the load distribution and the load deformation of the thread of the planetary roller screw mechanism (PRSM), a modification method of the roller thread is proposed. The nut side and the screw side of the roller thread are modified by different amount of modification, and the modified thread load distribution is calculated and analyzed. The results show that the effects of roller thread modification on the load distribution are significant, and the sensitivity of the load capacity of the nut and screw to the modification is different. Through the study of the influence of roller thread modification on thread load distribution, the optimal value of the roller thread modification on the nut side and the screw side is obtained under the PRSM parameters given in this paper, which provides a theoretical guidance for the future PRSM load balancing design.
Image Resteoration by BP Neural Based on PSO
Authors: Wang Wenzhong , Zhang Shusheng , Yu Suihuai
Published: October 2018

Based on PSO-BP algorithm combining particle swarm algorithm with BP neural network algorithm, this paper applies this algorithm to image restoration based on optimization. In the PSO-BP optimization algorithm model, on the one hand, the error of each training sample of BP algorithm is reversed, and the original image is used as the reference to modify the weight threshold of BP algorithm. On the other hand, it is optimized by forward particle swarm algorithm and BP algorithm. Finally, through the algorithm analysis and experimental data, the recovery effect of PSO-BP optimization algorithm is better than that of the same type algorithm.
Assessment of UAV's Operator Cognitive State Based on Behavior Signals
Authors: Xie Songyun , Li Yabing , Wang Wei , Meng Ya , Xie Xinzhou
Published: October 2018

For exploring the relationship between the mental or cognitive state and metric of vigilance test for unmanned aerial vehicle (UAV), a vigilance state evaluation method and sphere of application based on behavior signals is established. A classical vigilance test avoiding to crash is set. During the experiments, the subjective ratings as well as behavior signals (Response Time, Lapse) are recording. The dynamic changing of behavior signals is analyzed using statistical analysis. The results demonstrate that compared with continuous PVT test, the subject's mental workload in rest PVT test decreases dramatically. Compared other metrics, the speed of response time can reflect the dynamic changing of subject's mental state. The metric of Q-50 has a strong robustness for outlier of subject. Considering that the metrics have strong correlation with operator's cognitive state, they can effectively analyze the different workload.
A Hesitant Fuzzy Multi-Attribute Group Decision Making Method Based on Prospect Theory
Authors: Sun Peng , Zhang Jun , Zeng Hongbin
Published: October 2018

To solve a multi-attribute group decision-making problem, since its attribute weight is completely unknown, based on the prospect theory, a hesitant fuzzy multi-attribute group decision making method is proposed. According to the single-attribute-preference function provided by a decision maker, an improved entropy weight method is proposed to calculate the attribute weight. The hesitant fuzzy decision-making matrix is transformed into the prospect decision-making matrix which utilizes positive and negative ideal solutions as reference points. Then alternative schemes are ranked according to the ratio of profit to loss. Finally, a numerical example is provided to verify the effectiveness and feasibility of the proposed method.
A Target Tracking Algorithm Based on Mean Shift and Fast Template Matching
Authors: Duan Liangdi , Song Ping , Chen Zhong , Zhao Peng
Published: October 2018

This paper proposes a target tracking algorithm based on mean shift and template matching. The algorithm is divided into three stages:prediction, template matching, target positioning, and template updating. In the prediction stage, combined with the target position obtained from the previous frame tracking, the target position is predicted using the mean shift method, and the template matching search gate is defined with the predicted position as the center and the corresponding size as the coverage area. At the template matching stage, using fast template matching algorithm, the target template and search gate are quickly matched from coarse to fine, and the matching degree between matching result and target template is calculated. If the matching degree is greater than the given threshold, the fast template matching will be performed and the result will be used as the tracking result of the current frame image. Otherwise, the target position predicted by the mean shift algorithm is used as the tracking results of the current frame image. Finally, the template updating process is controlled by the tracking results of the current frame to update the target template, and the stable tracking of the target is finally completed. At the same time, the algorithm improves the robust of tracking by combining the advantages of color and edge features to the insensitivity of rotation and deformation. The method has fast calculation speed and high accuracy, it can meet real-time requirements.
Laparoscopic Duodenojejunostomy for the SMA Syndrome
Authors: Ehlers Till-Oliver , Tsamalaidze Levan , Pereira Lucio , Stauffer John
Published: October 2018

Objective The Superior Mesenteric Artery Syndrome (SMAS) was first described by Rokitansky in 1842. Clinical symptoms include postprandial pain, nausea, vomiting and weight loss. Duodenojejunostomy is the treatment of choice for patients with SMAS. We now present a case of a young female with SMAS who successfully underwent laparoscopic duodenojejunostomy.

Indications The first line treatment for SMAS is medical management, which includes infusion therapy, bowel rest, parenteral nutrition and a nasojejunal feeding tube inserted into the jejunum past the obstruction. If medical therapy fails, surgery is recommended.

Procedure A symptomatic patient with body mass index (BMI) of 19.4 kg/m2 underwent laparoscopic duodenojejunostomy. The patient tolerated the procedure well. The post-operative period was uneventful and the patient was discharged after three days. On six month follow up, the patient had gained weight and her symptoms were completely resolved.

Conclusion SMAS is still a poorly recognised pathology. A high index of suspicion should be given for patients with unclear causes of postprandial nausea, vomiting and abdominal pain, especially in young females. A laparoscopic approach seems to be safe and effective for patients with SMAS.
Aneurysmaruptur der abdominalen Aorta
Authors: Makaloski Vladimir , Schmidli Jürg , Wyss Thomas
Published: October 2018

Die Aneurysmaruptur der abdominalen Aorta ist eine lebensbedrohliche Situation. Aktuell sind die offene und endovaskuläre Behandlungsmethode in hochspezialisierten Zentren gleichwertig mit niedrigen Mortalitätsraten (15 – 20%). Das individuelle Patientenmanagement ist wichtiger als die gewählte Behandlungsoption. Die permissive Hypotonie mit Flüssigkeitsrestriktion sowie die geeignete Aneurysmaanatomie für die endovaskuläre Behandlung haben einen positiven Einfluss auf das Überleben. Koronare Herzkrankheit, chronische Niereninsuffizienz und schwerer hypovolämischer Schock haben einen negativen Einfluss auf das Überleben. Die Re-Interventionsrate nach endovaskulärer Versorgung ist deutlich höher als nach offenem Ersatz und erfordert lebenslange Nachkontrollen.
Regulatory T cells and their potential for tolerance induction in haemophilia A patients
Authors: Königs C. , Schmidt A. ,   ABIRISK consortium
Published: October 2018

FVIII inhibitors still are the major concern in treatment of haemophilia A patients by FVIII replacement therapy. Immune tolerance induction to reverse inhibitor formation fails in about 30% of treated patients. These patients face increased morbidity and mortality producing a need for new therapy strategies in the treatment of FVIII inhibitor-positive patients. Regulatory T cells are important modulators of the immune response and are also involved in the immune response to FVIII in haemophilia A patients. Additionally, regulatory T cells have been shown to play a role in tolerance induction induced by multiple experimental treatment regimes.

This review summarises the current knowledge on the role of regulatory T cells in the immune response to FVIII and tolerance induction strategies. Additionally, possible ways to engineer regulatory T cells as therapeutic agent in haemophilia A and current challenges of regulatory T cell therapies are discussed.
Routine measurement of serum calcitonin in patients with nodular thyroid disorders?
Authors: Wieler H. , Schmidt M. , Schwab R. , Goretzki P. E. , Schicha H. , Dietlein M.
Published: October 2018

In spite of the fact that the German Society of Endocrinology has recommended calcitonin as screening-parameter the majority of physicians in Germany do not routinely use calcitonin in patients with thyroid nodules to exclude medullary thyroid cancer (MTC). The future revision of the recommendation should describe reference values for each commercially available assay, separately for men and women (basal and after pentagastrin-stimulation), and should define sonomorphological inclusion criteria. The epidemiological database of the prevalence of MTC is controversial and the specificity of basal elevated calcitonin levels is limited up to the 5-fold of the upper reference level. If renal insufficiency, bacterial infection, and an alcohol- or druginduced stimulation of calcitonin is excluded, hypercalcitoninaemia should be confirmed by a second measurement (if necessary using another assay). Stimulation of calcitonin by use of pentagastrin is mandatory prior to the decision on thyroidectomy. A stimulated calcitonin level <100 pg/ ml justifies “wait and see”. If stimulated calcitonin levels range between 100 and 200 pg/ml or higher, the differentiation between C-cell hyperplasia and MTC remains uncertain, especially in men. The implementation of calcitonin- screening requires the definition of sonographic inclusion criteria and validation of each assay. Additional prerequisites are excellent logistic (short period between blood sampling and start of the laboratory test), knowledge of differential diagnoses, knowledge of the consumption of drugs and alcohol, availability of pentagastrin-testing and of moleculargenetic testing with full information to the patients and sufficient time before the decision on surgery is made. All this and the choice of a skilled surgeon, experienced in thyroidectomy and lymphadenectomy with a low rate of local complications are the rationale to recommend calcitonin-screening primarily in centers for thyroid disorders.
Cross-evaluation of Pharmacokinetic-Guided Dosing Tools for Factor VIII
Authors: Preijers T. , van Moort I. , Fijnvandraat K. , Leebeek F. , Cnossen M. , Mathôt R. ,   for the ‘OPTI-CLOT’ Study Group
Published: October 2018

Background Patients with severe and moderate haemophilia A are treated prophylactically with factor VIII (FVIII) concentrate. Individualization of prophylaxis can be achieved by pharmacokinetic (PK)-guided dosing.

Aim In this study, the performance of three PK tools (myPKFiT, Web-Accessible Population Pharmacokinetic Service-Hemophilia [WAPPS] and NONMEM) is compared.

Methods In 39 patients, with severe or moderate haemophilia A, blood samples were collected 4, 24 and 48 hours after administration of 50 IU kg−1 of recombinant FVIII (Advate [n = 30] or Kogenate [n = 9]). FVIII dose, FVIII activity and patient characteristics were entered into the three PK tools. Obtained PK parameters and dosing advises were compared.

Results myPKFiT provided PK parameters for 24 of 30 patients receiving Advate, whereas WAPPS and NONMEM provided estimates for all patients. Half-life was different among the three methods: medians were 12.6 hours (n = 24), 11.2 hours (n = 30) and 13.0 hours (n = 30) for myPKFiT, WAPPS and NONMEM (p < 0.001), respectively. To maintain a FVIII trough level of 0.01 IU mL−1 after 48 hours, doses for myPKFiT and NONMEM were 15.1 and 11.0 IU kg−1 (p < 0.01, n = 11) and for WAPPS and NONMEM were 9.0 and 8.0 IU kg−1 (p < 0.01, n = 23), respectively. In nine patients receiving Kogenate, WAPPS and NONMEM produced different PK-parameter estimates; half-life was 15.0 and 12.3 hours and time to 0.05 IU mL−1 was 69.2 and 60.8 hours, respectively (p < 0.01, n = 9). However, recommended doses to obtain these levels were not different.

Conclusion The three evaluated PK tools produced different PK parameters and doses for recombinant FVIII. Haematologists should be aware that recommended doses may be influenced by the choice of PK tool.