bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance study of millimetre‐wave MIMO channel in subway tunnel using directional antennas
Authors: Jiang Ye , Zheng Guoxin , Yin Xiaoyu , Saleem Asad , Ai Bo
Published: December 2017

This study studies the multiple‐input–multiple‐output (MIMO) performance in a tunnel scenario for the millimetre‐wave (mm‐wave) band. We simulated and measured channel impulse response at 28 GHz for grids of transmitters and receivers to study the feasibility of mm‐wave MIMO system for metro communication in tunnel environment. The ray‐tracing method was utilised to obtain the MIMO channel matrices. The performance of the channel is studied in terms of 2 × 2 and 4 × 4 MIMO, and the influences of antenna spacing on the channel capacity are investigated. The results provide a reference for the fifth‐generation wireless network in the future communication‐based train control system applications.
Fully integrated CMOS power amplifier using resistive current combining technique
Authors: Roy Palash , Dawn Debasis
Published: December 2017

This study presents a fully integrated complementary metal oxide semiconductor (CMOS) power amplifier (PA) covering LTE‐advanced bands from 825 to 915 MHz for cellular application and the bands of 978 MHz universal access transceiver mode and 1090 MHz extended squitter mode of an automatic dependent surveillance‐broadcast transmitter for the unmanned aircraft system. The 3.63 mm × 0.95 mm PA including all on‐chip input and output matching networks, fabricated using the 0.18 μm CMOS process exhibits peak output power of 24 dBm, modulated output power of >22 dBm at 978 MHz, the maximum power gain of 27 dB and bandwidth of 290 MHz.
Efficient approach for commutation failure immunity level assessment in hybrid multi‐infeed HVDC systems
Authors: Xiao Hao , Li Yinhong , Duan Xianzhong
Published: December 2017

Commutation failure (CF) of hybrid multi‐infeed high voltage‐direct current (HMIDC) systems, comprising line commutated converter‐based high‐voltage direct current (LCC‐HVDC) and voltage source converter‐based high‐voltage direct current (VSC‐HVDC) links, has been mainly analysed by electromagnetic transient simulation tools, resulting in heavy workload and long computational time. This study proposes an efficient approach for CF immunity level assessment based on CF immunity index in HMIDC systems. Thus, an equivalent dual‐bus analytical model of the HMIDC systems is first established, which then provides a theoretical basis for defining an equivalent voltage stability indicator (EVSI). It is then shown that such an EVSI index can be employed in the proposed approach. Moreover, the proposed approach is validated by a hybrid dual‐infeed HVDC system. In particular, an unexpected phenomenon is observed that the CF characteristic of the LCC‐HVDC link is somewhat deteriorated, due to the incorporation of the VSC‐HVDC link when the VSC‐HVDC link feeds into the alternating current system with both active and reactive power transferred in relatively high levels close to their limits.
Techno‐economic analysis of a PV–wind–battery–diesel standalone power system in a remote area
Authors: Adefarati Temitope , Bansal Ramesh C. , John Justo Jackson
Published: December 2017

The global acceptance of solar and wind resources for power generation has continued to increase due to the fluctuation of world oil and gas prices, recent advances in technology, high prices of fossil fuels, no direct greenhouse gas emission from solar and wind resources and government policies to support utilisation of renewable energy resources (RESs). In recent times, RESs have become a potential alternative to supply electricity to the rural communities where the extension of transmission and distribution lines is difficult due to technical and financial barriers. In view of this, this study deals with the optimisation of net present cost (NPC), fuel cost, operation cost and cost of energy (COE) of the hybrid system which consists of photovoltaic (PV), wind turbine generator (WTG), diesel generator and battery storage system. A hybrid power system is designed in this research work to serve a remote community. The optimisation of the key performance indicators of the proposed hybrid power system is done by using the hybrid optimisation model for electric renewable (HOMER). The results obtained from this research work are analysed to select the best options among the available configurations based on the lowest NPC and COE produced by each configuration. The simulation results from several case studies show that incorporation of PV and WTG have reduced the operating cost of the system.
Distribution fault outage cost evaluation and hotspot area recognition based on big data
Authors: Chen Jinming , Yang Yi , Wang Ziying , Li Yan , Guo Yajuan , Cui Jinli , Zhu Daohua
Published: December 2017

Power distribution faulting is one of the main reasons for the unplanned outage. In terms of the distribution fault outage, cost evaluation and hotspot area recognition are beneficial for utilities to develop schemes tailored for distribution operation, maintenance and upgrading. In this study, multi‐source data from marketing, distribution, and dispatching fields are effectively utilised for comprehensive information collection of medium‐voltage distribution network faults. A new approach to fault fuzzy location is proposed using distribution network topology and transformer outage duration. Meanwhile, fault outage cost is evaluated based on the short‐term load forecast of distribution transformers, which completely considers the impact of load transferring on multi‐power supply users. Furthermore, the distribution blackout events are mapped with geography information system, and the fault hotspot areas are highlighted by geographical grid virtualisation. The method proposed in this study has been validated using practical examples. This approach has been actually applied in Jiangsu distribution maintenance management.
Research on harmonic and overvoltage of photovoltaic power plant electricity energy collection system based on passive network model
Authors: Zhu Yongqiang , Hao Jiacheng , Li Xiangyu , Tang Qi , Xia Ruihua
Published: December 2017

In large‐scale photovoltaic (PV) power plant, the output power of each grid‐connected inverter is collected by electricity energy collection system and then is put into the grid. Previous studies have demonstrated that the harmonic problem may occur when PV inverters run in parallel even if all the PV inverters output power do individually satisfy the standards. Considering the electricity energy collection system, this study builds the model of harmonic transfer passive network for the typical topological structure of large‐scale grid‐connected PV power plant, and study the generating mechanism of harmonic and overvoltage. The harmonic power flow of a given calculation example is calculated by using node matrix method and the harmonic voltage magnification of each node is got. The point of common coupling is chosen as the study object. In this study, the impacts of cable parameters, the equivalent impedance of power grid and operation mode of PV power plant on the voltage magnification properties of the transfer network are analysed.
Discussion of positive fraction vector fitting for frequency‐dependent network equivalents
Authors: Hu Yizhong , Wu Wenchuan , Zhang Boming , Chen Xujiang
Published: December 2017

The positive fraction vector fitting (PFVF) is a special method to guarantee the passivity of rational models such as frequency‐dependent network equivalents. It involves constraints that enforce each fraction of the rational model to be passive, which are much stricter than the original passive requirements. PFVF lacks theoretical foundation but works well in practise. This study explains the rationality of PFVF by revealing important features of rational models that the complex‐pole fractions corresponding to dominant resonance peaks can be adjusted passive through a minor change. The numerical case corroborates the theoretical analysis.
Energy management system controller for a rural microgrid
Authors: Kumar Abhishek , Deng Yan , He Xiangning , Kumar Praveen , Bansal Ramesh C.
Published: December 2017

An energy management system (EMS) for an isolated microgrid in a typical rural location is presented. The rural microgrid consists of locally available renewable energy resources, such as solar, wind, along with diesel generator for backup and battery as storage to meet the electrical load demand. The grid electricity supply in the village is characterised by frequent outages with the poor quality of supply. Firstly, the proposed system controller's (PSC) dispatch rules are formulated using MATLAB. Then, PSC rules designed in MATLAB are integrated with hybrid optimisation of multiple electric renewables (HOMER PRO) software to design an isolated microgrid. A detailed techno‐economic analysis is presented to obtain the cost‐effective sizing of the microgrid considering a yearly load growth over the project lifetime. Finally, to show the effectiveness, a comparative analysis of the PSC with the inbuilt load following controller of the HOMER PRO is also illustrated. Also, a simple procedure showing the integration of MATLAB with HOMER PRO is outlined briefly.
Analysis of the impact of distributed generation on grounding method of distribution network
Authors: Qian Wang , Jun Lu , Jiandong Duan , Wangjing Tan
Published: December 2017

As more and more distributed generation (DG) access to distribution network, the study of the impact of DG on distribution network becomes an important issue. When DG units are introduced in distribution systems, the power network structure had changed, it will influence the original grounding method of the distribution network; so, it is necessary to analyse the effect of DG connecting on distribution network. Here, for different operation characteristics of DG, a simulation model of DG connecting to 10 kV distribution network has established, and the simulation results of DG with different grounding method connected to distribution network have obtained. The results showed that ungrounded DG connected to distribution network has little effect on the original grounding method of distribution network, but the low‐resistance grounding DG and grounded DG connected to distribution network have impact on the original grounding method of distribution network. So, DG has to be considered an important factor when selecting the neutral grounding model of distribution network.
One‐step MPPT method based on five‐parameter model of PV panel
Authors: Miao Jierong , Xie Da , Fan Ruixiang
Published: December 2017

Traditionally, maximum power point tracking control (MPPT) methods are independent of the mathematical model and require multi‐step adjusting of the inverter, resulting in multiple disturbances of the photovoltaic (PV) system. Actually, the PV cell has a definite U –I curve at a certain degree of illuminance and temperature, which can be described in a mathematical model. This study proposes a one‐step MPPT method based on five‐parameter model. Utilising voltage and current measurements, the DC/DC inverter of each PV panel obtains equations for five parameters and solves them via Newton iteration method. According to P –U curve, the derivative of P to U is zero. Thus, an implicit equation of the maximum power can be given along with a constraint. Considering the bimodal characteristics of P –U curve under cloud shade condition, the constraint prevents the result to converge to the low peak point. Then the DC/DC inverter can adjust the PV system to MPP by one step. Furthermore, since the five parameters vary at different illuminance and temperature, the database can be established based on the correspondence between condition and parameters, which can give back to DC/DC inverter to improve the tracking efficiency.
Protection principle for MMC‐HVDC DC lines based on boundary signals
Authors: Lv Cheng , Tai Nengling , Zheng Xiaodong
Published: December 2017

The protection of modular multilevel converter (MMC) is a research interest in the flexible DC transmission, particularly with the increasing penetration of distributed generators. A 21‐level MMC converter is firstly modelled in PSCAD/EMTDC. Different types of DC fault characteristics are analysed in detail. Based on these transient features, a definition of signal distance is then introduced combining boundary DC currents. Furthermore, based on the difference of boundary signals, a protection principle for MMC‐HVDC DC lines is proposed. Various simulations are carried out in PSCAD/EMTDC on different fault conditions, such as different fault resistances and distances. Finally, the proposed protection principle is tested under different fault types and locations. Simulation results show that the proposed protection principle is feasible and reliable.
Synergistic dispatch of generation and network in wind power integrated power system
Authors: Sun Donglei , Yang Jinhong , Liu Xiaoming , Wu Kuihua , Cao Xiangyang , Bo Qibin
Published: December 2017

With the increasing penetration of wind power and the diversified development of electric load, power system is characterised by complex uncertainties, which bright formidable challenges for the operation of power system. It can promote the capability of accommodating uncertainties to exploit the synergistic capability of complementarity characteristics between power source and electric network. Considering voltage support for the realisation of power balance under the uncertain circumstance, the relationship between network and power balance is analysed and an optimisation model for synergistic dispatch of power source and electric network is proposed to deal with the complex uncertainty. The core of the proposed model is that the cooperation mechanism of network structure optimisation is incorporated into the coordinated economic dispatch with the consideration of physical law of electric network to deal with voltage security and network constraints. Then the proposed model is solved by the combination of genetic algorithm and non‐linear primal‐dual interior point method. Finally, example analyses are conducted to illustrate the effectiveness of the proposed method.
Coordination of two‐stage surge protective device in low‐voltage system under mixed waves
Authors: Zheng Yiming , Gong Chunyan , Hu Wei , Zhu Zhengyuan
Published: December 2017

In the low‐voltage distribution system, single‐stage surge protective device (SPD) cannot reach the lightning protection requirements for some sensitive devices. Thus, multi‐stage SPD is adopted to achieve better protection effects. In this study, coordination regulation of two‐stage SPD was investigated under the mix waves of 20 kV/10 kA. Four circumstances of terminal loads, no‐load, capacitance load, inductance load and resistance load were considered as well as the cable length in the investigation. The simulation results indicated that the current ratio of the SPD1 is ∼60–100%, which endures the most lightning current. The SPD2 may influence the waveform of the residual voltage, leading to high‐voltage amplitude of high oscillation frequency, which may have significant impact on the devices.
Research of transmission delay test method in smart substations
Authors: Xinyue Gong , Da Zhou , Yun Teng , Qiangsheng Bu , Lei Gao
Published: December 2017

For the sampling circuit of intelligent substation, more and more data conversion and information transmission links lead to an increase in sampling delay time, which is not conducive to the rapid and reliable transmission of information. This study analyses the mechanism of delay in the sampling loop of intelligent substation, and proposes an improved measurement method based on the detection delay of wavelet mutation point. This method can accurately measure the delay of the entire period in the sampling cycle in excess of one waveform cycle. Also, the correctness of the method is verified by simulation and field experiment.
Optimal strategy for distribution system with PV based on voltage violation regulation
Authors: Jin Shanhong , He Weiguo , Zhang Jingwei , Zhu Xiang , Liu Haoming
Published: December 2017

The high penetration of distributed photovoltaic (PV) can bring about huge economic and environmental benefits in the distribution network. While at the same time, it can result in the voltage violation in power system. Due to the two‐quadrant power output characteristics of PV inverter, it is possible to regulate voltage violation via utilising the reactive power output of PV inverter instead of traditional reactive power compensation devices. In this study, a global voltage regulation strategy has been addressed by taking the indices of voltage violation regulation and active power loss of distribution network into consideration, and voltage limit violation is processed based on the concept of hard and soft voltage boundary constraints. Differential evolution algorithm is introduced to solve the optimisation model. Finally, it was simulated in IEEE‐33 node distribution system, results of example analysis confirm that the proposed strategy can optimise the reactive and active power of PV, which can not only regulate the voltage violation but also realise the economic operation of the distribution system.
Optimal single phase smart meter design
Authors: T. Mbungu Nsilulu , Naidoo Raj , Bansal Ramesh C. , Bipath Minnesh
Published: December 2017

This study presents a new generation of smart meter that can optimally manage the energy demand. This device optimises the consumer's overall energy cost in a real‐time environment by giving the customer an opportunity to set a minimal electricity tariff. It consists of giving both utility and consumers of the electricity an opportunity to manage the supply and demand of the energy. From the supply point of view, this is based on the conceptual framework of the standard advanced metering infrastructure. While on the consumer side, an additional optimal design strategy is added into the device that can communicate with all electrical systems by automatically switching on and off some specified loads. This application is developed based on the scheme of configuring into the smart meter two principal supply setting systems which contain some non‐optimal and optimal supply nodes. As a compact optimal smart meter system, it will ensure appropriate control and reduce the cost of electricity. Moreover, it can encourage the use of renewable energy resources and resolve several issues of power system integration.
Reactive power control strategy of DFIG‐based wind farm to mitigate SSO
Authors: Wu Xi , Guan Yajing , Ning Wei
Published: December 2017

Wind farms connected with series compensated transmission network suffer from the risk of sub‐synchronous oscillation (SSO). Moreover, the strong active and reactive power control ability of doubly fed induction generator (DFIG) exerts non‐negligible influence on SSO. In this study, the impacts of adjustable parameters on SSO are studied based on eigenvalue analysis. The results indicate that increasing inductive reactive power produced by DFIG can provide positive damping to the system; furthermore, the universality of this rule is verified in the whole operating region of DFIG. According to the rule, a reactive power control strategy of DFIG is proposed for SSO suppression. The reactive power is suggested to increase gradually once the SSO is detected and stop until SSO is suppressed or the reactive power limit is reached. The proposed control method is a low‐cost method, which only need to adjust the reactive power reference value of DFIG to damp SSO. Finally, the time‐domain simulation results illustrate the validity and adaptability of the proposed SSO reactive power control strategy.
Comparison of EV smart charging strategies from multiple stakeholders' perception
Authors: Rawat Tanuj , Niazi Khaleequr Rehman
Published: December 2017

Electric vehicles (EVs) will become an integral part of the future smart grid. Random charging of EVs may give birth to many issues such as increasing losses, voltage deviation, and increase in peak. The threats imposed by random charging can be conquered by smart or coordinated charging strategies. The liberalisation of energy sector creates an opportunity for different market actors to use flexible EV demand for their own benefits. Thus, the objectives for smart EV charging can be formulated to meet the interest of a single stakeholder or multiple stakeholders. In this study, a comparative analysis of three smart charging strategies from different stakeholders' perception/interests – (i) aggregator (also representing customers), (ii) Network operator, and (iii) both aggregator and network operator simultaneously – while considering different EV penetration is presented in terms of increase in peak load, peak‐valley difference, load factor, and total charging cost. The influence of fast charging and battery charging efficiency on these results is also discussed.
The XXL Survey
Authors: Adami C. , Giles P. , Koulouridis E. , Pacaud F. , Caretta C. A. , Pierre M. , Eckert D. , Ramos-Ceja M. E. , Gastaldello F. , Fotopoulou S. , Guglielmo V. , Lidman C. , Sadibekova T. , Iovino A. , Maughan B. , Chiappetti L. , Alis S. , Altieri B. , Baldry I. , Bottini D. , Birkinshaw M. , Bremer M. , Brown M. , Cucciati O. , Driver S. , Elmer E. , Ettori S. , Evrard A. E. , Faccioli L. , Granett B. , Grootes M. , Guzzo L. , Hopkins A. , Horellou C. , Lefèvre J. P. , Liske J. , Malek K. , Marulli F. , Maurogordato S. , Owers M. , Paltani S. , Poggianti B. , Polletta M. , Plionis M. , Pollo A. , Pompei E. , Ponman T. , Rapetti D. , Ricci M. , Robotham A. , Tuffs R. , Tasca L. , Valtchanov I. , Vergani D. , Wagner G. , Willis J. ,   and the XXL consortium
Published: December 2017

Context. In the currently debated context of using clusters of galaxies as cosmological probes, the need for well-defined cluster samples is critical.

Aims. The XXL Survey has been specifically designed to provide a well characterised sample of some 500 X-ray detected clusters suitable for cosmological studies. The main goal of present article is to make public and describe the properties of the cluster catalogue in its present state, as well as of associated catalogues of more specific objects such as super-clusters and fossil groups.

Methods. Following from the publication of the hundred brightest XXL clusters, we now release a sample containing 365 clusters in total, down to a flux of a few 10−15 erg s−1 cm−2 in the [0.5–2] keV band and in a 1′ aperture. This release contains the complete subset of clusters for which the selection function is well determined plus all X-ray clusters which are, to date, spectroscopically confirmed. In this paper, we give the details of the follow-up observations and explain the procedure adopted to validate the cluster spectroscopic redshifts. Considering the whole XXL cluster sample, we have provided two types of selection, both complete in a particular sense: one based on flux-morphology criteria, and an alternative based on the [0.5–2] keV flux within 1 arcmin of the cluster centre. We have also provided X-ray temperature measurements for 80% of the clusters having a flux larger than 9 × 10−15 erg s−1 cm−2.

Results. Our cluster sample extends from z ~ 0 to z ~ 1.2, with one cluster at z ~ 2. Clusters were identified through a mean number of six spectroscopically confirmed cluster members. The largest number of confirmed spectroscopic members in a cluster is 41. Our updated luminosity function and luminosity–temperature relation are compatible with our previous determinations based on the 100 brightest clusters, but show smaller uncertainties. We also present an enlarged list of super-clusters and a sample of 18 possible fossil groups.

Conclusions. This intermediate publication is the last before the final release of the complete XXL cluster catalogue when the ongoing C2 cluster spectroscopic follow-up is complete. It provides a unique inventory of medium-mass clusters over a 50 deg2 area out to z ~ 1.
Excitation and charge transfer in low-energy hydrogen atom collisions with neutral oxygen
Authors: Barklem P. S.
Published: December 2017

Excitation and charge transfer in low-energy O+H collisions is studied; it is a problem of importance for modelling stellar spectra and obtaining accurate oxygen abundances in late-type stars including the Sun. The collisions have been studied theoretically using a previously presented method based on an asymptotic two-electron linear combination of atomic orbitals (LCAO) model of ionic-covalent interactions in the neutral atom-hydrogen-atom system, together with the multichannel Landau-Zener model. The method has been extended to include configurations involving excited states of hydrogen using an estimate for the two-electron transition coupling, but this extension was found to not lead to any remarkably high rates. Rate coefficients are calculated for temperatures in the range 1000–20 000 K, and charge transfer and (de)excitation processes involving the first excited S-states, 4s.5So and 4s.3So, are found to have the highest rates.
Using the CIFIST grid of CO5BOLD
3D model atmospheres to study the effects of stellar granulation on photometric colours
Authors: Bonifacio P. , Caffau E. , Ludwig H.-G. , Steffen M. , Castelli F. , Gallagher A. J. , Kučinskas A. , Prakapavičius D. , Cayrel R. , Freytag B. , Plez B. , Homeier D.
Published: December 2017

Context. The atmospheres of cool stars are temporally and spatially inhomogeneous due to the effects of convection. The influence of this inhomogeneity, referred to as granulation, on colours has never been investigated over a large range of effective temperatures and gravities.

Aim. We aim to study, in a quantitative way, the impact of granulation on colours.

Methods. We use the CIFIST (Cosmological Impact of the FIrst Stars) grid of CO5BOLD (COnservative COde for the COmputation of COmpressible COnvection in a BOx of L Dimensions, L = 2, 3) hydrodynamical models to compute emerging fluxes. These in turn are used to compute theoretical colours in the UBV RI, 2MASS, HIPPARCOS, Gaia and SDSS systems. Every CO5BOLD model has a corresponding one dimensional (1D) plane-parallel LHD (Lagrangian HydroDynamics) model computed for the same atmospheric parameters, which we used to define a “3D correction” that can be applied to colours computed from fluxes computed from any 1D model atmosphere code. As an example, we illustrate these corrections applied to colours computed from ATLAS models.

Results. The 3D corrections on colours are generally small, of the order of a few hundredths of a magnitude, yet they are far from negligible. We find that ignoring granulation effects can lead to underestimation of Teff by up to 200 K and overestimation of gravity by up to 0.5 dex, when using colours as diagnostics. We have identified a major shortcoming in how scattering is treated in the current version of the CIFIST grid, which could lead to offsets of the order 0.01 mag, especially for colours involving blue and UV bands. We have investigated the Gaia and HIPPARCOS photometric systems and found that the (G − Hp), (BP − RP) diagram is immune to the effects of granulation. In addition, we point to the potential of the RVS photometry as a metallicity diagnostic.

Conclusions. Our investigation shows that the effects of granulation should not be neglected if one wants to use colours as diagnostics of the stellar parameters of F, G, K stars. A limitation is that scattering is treated as true absorption in our current computations, thus our 3D corrections are likely an upper limit to the true effect. We are already computing the next generation of the CIFIST grid, using an approximate treatment of scattering.
Effect of characteristics of fine iron ores on the granulation behavior of concentrate in sintering granulation process
Authors: Wu Shengli , Que Zhigang , Zhai Xiaobo , Li Kailang
Published: December 2017

Concentrates have advantages of high ferrous grade, less harmful impurities and lower price. However, the small size and poor granulation behavior of concentrates could deteriorate the permeability of the sinter bed and reduce sinter productivity, thus making it difficult to use concentrates effectively. Therefore, in order to strengthen the granulation behavior of concentrates, granulation experiments were carried out and experiment samples made with one kind of concentrates and five kinds of fine iron ores were produced in this paper. Then, the effects of water absorbility and wettability of fine iron ores on granulation behavior of concentrates were investigated. Furthermore, optimized ore blending recipes were proposed to strengthen the granulation behavior of concentrates by sinter pot tests. Results show that the granulation behavior of concentrates was improved for the samples exhibiting high maximum capillary water and small contact angle in fine iron ores. Compared with the scheme of blending ores containing 15 mass% concentrate, the growth index of quasi-particles increased by 20.62% in the case of iron ore BR-2 replacing half of iron ore BR-1, the vertical sintering speed went up from 26.32 to 29.26 mm min−1, the productivity increased from 1.95 to 2.20 t m−2 h−1. The growth index of the quasi-particles increased by 30% when using iron ore AR-2 to replace half of iron ore AR-1. The vertical sintering speed and the productivity of sinter improved to 29.82 mm min−1 and 2.24 t m−2 h−1, respectively. The results help to improve the granulation behavior of concentrates by optimizing the blending ore recipes, based on the characteristics of fine iron ores, and thus use these concentrates more efficiently in the sintering process.
Scrap melting model for steel converter founded on interfacial solid/liquid phenomena
Authors: Kruskopf Ari , Holappa Lauri
Published: December 2017

The primary goal in steel converter operation is the removal of carbon from the hot metal. This is achieved by blowing oxygen into the melt. The oxidation of carbon produces a lot of heat. To avoid too high temperatures in the melt cold scrap (recycled steel) is charged into the converter. The melting rate is affected by heat and carbon mass transfer. A process model for steel converter is in development. This model is divided into several modules, which are fluid dynamics, heat- and mass-transfer, scrap melting and chemical reactions. This article focuses on the development of the scrap melting module. A numerical model for calculating temperature and carbon concentration in the melt is presented. The melt model is connected with the solid scrap model via solid/liquid interface. The interface model can take into account solidification of iron melt, melting of solidified layer, a situation without such phase changes, and scrap melting. The aim is to predict the melting rate of the scrap including the properties of the hot metal. The model is tested by calculating the melting rates for different scrap thicknesses. All of the stages in the interface model were taking place in the test calculations.
Hierarchical optimization on an unbounded parallel-batching machine
Authors: He Cheng , Li Li
Published: December 2017

This paper studies a hierarchical optimization problem on an unbounded parallel-batching machine, in which two objective functions are maximum costs, representing different purposes of two decision-makers. By a hierarchical optimization problem, we mean the problem of optimizing the secondary criterion under the constraint that the primary criterion is optimized. A parallel-batching machine is a machine that can handle several jobs in a batch in which all jobs start and complete respectively at the same time. We present an O(n4)-time algorithm for this hierarchical scheduling problem.
Advances in Neuro-Ophthalmic Imaging
Authors: Bouffard Marc , Prasad Sashank
Published: December 2017

Recent years have brought a rapid evolution of diagnostic imaging studies in neuro-ophthalmic practice. Optical coherence tomography (OCT) and several of its derivations (swept-source OCT, enhanced-depth imaging OCT, and OCT-angiography) are advancing diagnosis, and in some cases prognostication, in a variety of inflammatory, ischemic, and compressive optic neuropathies. These technologies hold potential in the laboratory as well, yielding insights into the mechanisms of a variety of neurological conditions. In addition, further developments in magnetic resonance imaging and ultrasonography techniques are shaping the approach to the diagnosis of giant cell arteritis.
Primäre und sekundäre glomeruläre Erkrankungen – Update 2017
Authors: Benck Urs , Banas Bernhard , Birck Rainer
Published: December 2017

Was ist neu?

IgA-Nephropathie Eine gezielt-enterale Budesonidgabe über 9 Monate verbessert die Proteinurie und stabilisiert die Nierenfunktion bei Patienten mit IgAN. Das gleiche gilt für eine orale Methylprednisolongabe über 6 – 8 Monate. Beide Studien zeigen relevante steroidassoziierte Nebenwirkungen, die Nutzen/Risiko-Bewertung einer Steroidbehandlung bei IgAN ist deshalb weiter unklar. B-Zell-Depletion durch Rituximab hat bei IgAN-Patienten keine positiven Effekte.

Membranöse Glomerulonephritis Humane Auto-Antikörper gegen das Podozytenprotein THSD7A können die Erkrankung klinisch und histologisch auslösen. Dies gilt äußerst wahrscheinlich analog für die häufigeren Phospholipase-A2-Rezeptor-Antikörper (PLA2R-Ak). Die pathogenetisch kausale Rolle dieser MGN-assoziierten Auto-Antikörper ist bewiesen. Eine erste randomisierte Phase 3-Studie ergab, dass Rituximab bei Patienten mit MGN im Vergleich zur supportiven Therapie höhere Proteinurie-definierte Remissionsraten erzielt. Ein positiver Effekt auf die Nierenfunktion wurde nicht gezeigt.
Update unkomplizierte Harnwegsinfektionen – Die neue Leitlinie 2017
Authors: Helbig Sina , Mandraka Falitsa
Published: December 2017

Was ist neu?

Asymptomatische Bakteriurie Laut der neuen Leitlinie soll der Begriff „asymptomatische“ Harnwegsinfektion nicht mehr verwendet werden. Es wird zwischen einer symptomatischen Harnwegsinfektion und der asymptomatischen Bakteriurie unterschieden.

Diagnostik Anamnesetools, wie gezielte Fragen zur klinischen Symptomatik oder auch der „acute cystitis symptom score“ (ACSS) können hilfreich sein. Bei typischer Anamnese ist die Durchführung des Urinstatus verzichtbar, da er nicht zur weiteren Erhöhung der Diagnosesicherheit beiträgt.

Therapie Harnwegsinfektionen sind ein häufiger Grund für Antibiotikaverschreibungen. Die neue Richtlinie berücksichtigt daher eine kritischere Diagnosestellung und die Notwendigkeit der rationalen Antibiotikatherapie („Antibiotic Stewardship“), u. a. auch die gezieltere Abgrenzung der asymptomatischen Bakteriurie von der symptomatischen Harnwegsinfektion. Neu aufgenommen in die Erstlinienempfehlungen wurde das Antibiotikum Nitroxolin. Das bereits zur Therapie der ersten Wahl empfohlene Pivmecillinam ist nun in Deutschland zugelassen. In die Antibiotikaempfehlungen wurden Gewichtungen hinsichtlich Eradikationsrate, Empfindlichkeit, Kollateralschäden und Sicherheit/Nebenwirkungen aufgenommen mit dem Ziel einer individuelleren Therapiewahl. Die symptomatische Therapie mit Ibuprofen kann nach Abwägung im Arzt-Patientengespräch eine nicht-antibiotische Therapiealternative darstellen.

Prophylaxe Der Stellenwert der Immunprophylaxe wurde neu in die Leitlinien aufgenommen und bewertet.
Kardiovaskuläre Komplikationen onkologischer Therapien: 2016 Positionspapier der Europäischen Gesellschaft für Kardiologie (ESC)
Authors: Bönner Florian , Fenk Roland , Kochanek Matthias , Pfister Roman
Published: December 2017

Was ist neu?

Pathophysiologie und Manifestation Mechanismen und Häufigkeiten kardiovaskulärer Komplikationen sind für die Vielzahl aktueller onkologischer Therapeutika systematisch zusammengefasst, gegliedert nach 11 Krankheitskomplexen.

Versorgungsstrukturen In Analogie zum „Herz“- oder „Endokarditis-Team“ wird die Implementierung von kardio-onkologisch spezialisierten, interdisziplinären Teams vorgeschlagen, die sich lokal um Monitoring und Management kardiovaskulärer Komplikationen und auch die Langzeitnachsorge onkologischer Patienten kümmern.

Diagnostik und Definition Die diagnostische Basiserhebung vor Therapie besteht aus kardiovaskulärer Anamnese und je nach erwarteten Komplikationen EKG, Ischämieuntersuchung und Echokardiografie. Die Echokardiografie ist die Methode der Wahl zur Kontrolle der kardialen Funktion. Kardiotoxizität wird als Abfall der Ejektionsfraktion um mehr als 10 Prozentpunkte unter den unteren Referenzgrenzwert (< 50 %) definiert. Neue Entwicklungen auch parametrischer Bildgebung des Kardio-MRTs eröffnen neue Perspektiven zur Charakterisierung des Myokards und Interstitiums bei kardiotoxischen Manifestationen.

Prävention und Therapie Risikofaktoren, prävalente oder während der Therapie aufgetretene manifeste kardiovaskuläre Erkrankungen wie Herzinsuffizienz, Vorhofflimmern oder Koronarkrankheit werden nach aktuell gültigen Leitlinien behandelt. Bei hohem Risiko für Kardiotoxizität können präventiv ACE-Hemmer oder ß-Blocker eingesetzt werden.
Die erste deutschsprachige Leitlinie zu autoimmunen Lebererkrankungen
Authors: Schramm Christoph , Strassburg Christian
Published: December 2017

Was ist neu?

Serologische Diagnostik bei autoimmunen Lebererkrankungen Die Serologie ist ein wichtiger Baustein in der Differenzialdiagnose autoimmuner Lebererkrankungen. Das Immunfluoreszenzmuster der antinukleären Antikörper (ANA) liefert wichtige Hinweise auf das Vorliegen einer primär biliären Cholangitis (PBC) und sollte berichtet werden.

Autoimmune Hepatitis (AIH) Die Beurteilung der Leberhistologie ist für die Diagnose der AIH wichtig. Über den Verlauf der Erkrankung geben in der Regel die Transaminasen, das Serum IgG (beide sollten im Normbereich liegen) und nicht-invasive Methoden der Fibrosebestimmung (wie die transiente Elastografie) ausreichende Informationen.

Primär Biliäre Cholangitis (PBC) Ca. 30 % der PBC-Patienten sprechen nicht ausreichend auf die Standardtherapie mit Ursodeoxycholsäure (UDCA) an. Für diese Patienten wurde kürzlich die zusätzliche Therapie mit Obeticholsäure zugelassen.

Primär Sklerosierende Cholangitis (PSC) Die MRT/MRCP hat in der Diagnostik und Verlaufskontrolle der Gallengangspathologie eine zentrale Stellung. Nach einer endoskopischen Dilatationstherapie von Stenosen sollte, wenn möglich, auf eine Stenteinlage verzichtet werden.

IgG4-assoziierte Cholangitis (IAC) Die Diagnose der IAC ist nach wie vor schwierig. Die IAC spricht in den frühen Stadien sehr gut auf eine Steroidtherapie an, wobei 20 – 40 mg pro Tag Prednisolon in der Initialtherapie ausreichen.
Aktuelle Aspekte zu Diagnostik und Therapie des Lungenkarzinoms
Authors: Griesinger Frank
Published: December 2017

Was ist neu?

Molekulare Alterationen Neben den bekannten molekularen Alterationen (EGFR; ALK und ROS), die vor Beginn einer Erstlinientherapie in Ring-zertifizierten Labors getestet werden sollten, wurde Dabrafenib und Trametinib bei BRAF-V600E-Mutationen zugelassen Des Weiteren wurden Daten zu Crizotinib bei c-MET Exon 14 Skipping-Mutationen (Off-Label-Use) publiziert. Die Therapie von EGFR- und ALK-alterierten Patienten hat sich mit Osimertinib (T790 M spezifische Substanz) sowie Zweit- und Drittgenerations-ALK-Inhibitoren deutlich verbessert. Die „liquid biopsy“ (flüssige Biopsie) ist zur Evaluation von genetischen Alterationen bei Lungenkarzinom Standard.

Immuncheckpointinhibitoren Immuncheckpointinhibitoren stellen die 5. Säule der Krebstherapie beim Lungenkarzinom dar und haben sich in der Zweitlinie beim nicht kleinzelligen Lungenkarzinom (NSCLC) als Standard etabliert. 25 – 30 % der NSCLC-Patienten exprimieren PD-L1 auf Tumorzellen hoch. Diese können seit Anfang des Jahres chemotherapiefrei mit Pembrolizumab behandelt werden.

Neue UICC-Klassifikation und oligometastastische Erkrankung (OMD) Die 8. UICC Klassifikation führt das Stadium M1b beim NSCLC ein, das eine kurative Therapieoption darstellt und daher diagnostiziert werden sollte.
Hidradenitis suppurativa (Acne inversa) – Aktuelles zu Komorbidität und Therapie
Authors: Wilden S. , Schepler H. , von Stebut E.
Published: December 2017

Lange unter der Rubrik „orphan disease“ gelistet, erfuhr die Hidradenitis suppurativa (HS) zuletzt mit der Zulassung von Adalimumab neue Aufmerksamkeit. Was mit einzelnen Knoten und Abszessen anfängt, endet unter mangelnder Behandlung nicht selten in ausgedehnter Fistelbildung und Vernarbung, die zum Teil mit erheblichen Bewegungseinschränkungen, sozialem Rückzug und Isolation einhergehen.

In Deutschland geht man derzeit von einer Prävalenz von etwa 1 % aus 1
2. Somit kommt diese multifaktoriell bedingte Erkrankung ähnlich häufig vor wie die Psoriasis, doch bekommt sie bei weitem nicht die gleiche Aufmerksamkeit. Vielleicht ist dies auch der Tatsache geschuldet, dass das Therapieangebot mit (noch) nur einer zugelassenen medikamentösen Therapie (Adalimumab) sehr viel kleiner ausfällt als beispielsweise das der Psoriasis.
Ein seltener Fall von Lambert-Eaton-Myasthenischem-Syndrom assoziiert mit Merkelzell-Karzinom und präexistenter Vitiligo
Authors: Troyanova-Slavkova S. , Seidl C. , Bortkevicius P. , Eickenscheidt L. , Kowalzick L.
Published: December 2017

Das Lambert-Eaton-Myasthenische-Syndrom (LEMS) ist eine sehr seltene neurologische Autoimmunerkrankung, für die eine proximal betonte Muskelschwäche charakteristisch ist. Die Erkrankung ist als paraneoplastisches neurologisches Symptom bekannt, das besonders mit neuroendokrinen Tumoren assoziiert ist und v. a. beim kleinzelligen Lungenkarzinom auftreten kann. Das Merkelzell-Karzinom (MCC) ist eine seltene Malignität an der Haut, die eine Tendenz für lokale Rezidive und regionale Lymphknotenmetastasen hat. Es tritt v. a. bei älteren Patienten an den sonnenexponierten Hautarealen als schnell wachsendes intrakutanes Knötchen auf. Hier stellen wir einen Fall von MCC vor, das bei einem vergleichsweise jungen 40-jährigen Patienten mit LEMS und Vitiligo diagnostiziert wurde. Nach einer Überprüfung der Literatur zeigt sich das Auftreten von LEMS mit MCC und Vitiligo als eine Rarität.
Gesellschaft für Phytotherapie e. V. veranstaltete zum wiederholten Mal erfolgreich das 2. Modul der Fortbildungsreihe für Ärzte und Apotheker
Authors: Nieber Karen , Schwöppe Cornelia
Published: December 2017

Nachdem im Frühjahr 2017 erneut die Fortbildungsreihe der GPT „Phytopharmaka und Phytotherapie“ mit dem 1. Modul gestartet wurde, fand vom 15.–17.9.2017 zum wiederholten Mal das 2. Modul der Fortbildung im Hotel Kranichhöhe, Much / Bergisches Land statt.
Die Sonografie des Sehnervs: ein neues bettseitiges Diagnostikum in der Intensivmedizin?
Authors: Hohmann Christopher , Koch Konrad , Pfister Roman , Michels Guido
Published: December 2017

Anamnese und klinische Befunde Ein 76-jähriger Patient erlitt aufgrund eines infarktbedingten kardiogenen Schocks einen beobachteten Herz-Kreislauf-Stillstand. Aufgrund einer nicht durchgeführten Laienreanimation ergab sich eine No-flow-Zeit von ungefähr 10 Minuten. Nach 25-minütigen Reanimationsmaßnahmen konnte ein Spontankreislauf etabliert werden, sodass der Patient umgehend einer Notfallkoronarangiografie zugeführt wurde. Nach Koronarstenting wurde der Patient auf die kardiologische Intensivstation aufgenommen und entsprechend den Leitlinien des infarktbedingten kardiogenen Schocks versorgt.

Therapie und Verlauf Nach zielgerichtetem Temperaturmanagement und anschließender Beendigung der Analgosedierung kam es zu einer verzögerten Aufwachreaktion. In der Laborchemie zeigte sich ein deutlicher Anstieg der neuronenspezifischen Enolase als Marker für hypoxischen Hirnschaden, sodass eine fokussierte Sonografie des Nervus opticus erfolgte. Die sonografische Messung des Durchmessers des Nervus opticus ergab mit 7 mm Hinweise für einen erhöhten intrakraniellen Druck. In der unmittelbar durchgeführten kranialen Computertomografie waren Zeichen einer schweren globalen Hypoxie mit vor allem parieto-okzipito-temporal aufgehobener Mark-Rinden-Differenzierung sichtbar.

Folgerung Die bettseitige Sonografie in der Intensivmedizin sollte bei klinischen und/oder laborchemischen Zeichen für eine anoxische Hirnschädigung und/oder Hirndruckerhöhung die Beurteilung des Nervus opticus beinhalten. In der Zusammenschau der Befunde sollte gegebenenfalls frühzeitig eine weitere apparative neurologische Diagnostik initiiert werden.
Plattenepithelkarzinom nach langjähriger Arsenexposition in der Porzellanindustrie
Authors: Troyanova-Slavkova S. , Schierle K. , Bielfeld C. , Kowalzick L.
Published: December 2017

Die Inzidenz von epithelialen Hauttumoren wie Plattenepithelkarzinomen steigt weltweit deutlich an. Viele Risikofaktoren für deren Entstehung sind schon bekannt, u. a. auch die langjährige Arsenexposition. Wir berichten über den Fall einer 78-jährigen Patientin, die seit mehr als 30 Jahren in der Porzellanindustrie als Malerin tätig war und bei uns aufgrund eines exophytischen, schnell wachsenden Tumors am Handrücken links vorstellig wurde. Histologisch konnte ein Plattenepithelkarzinom diagnostiziert werden. Von Seiten der Patientin wurde eine langjährige berufsbedingte Tätigkeit mit Kobaltfarben in der Porzellanindustrie angegeben. Kobalt kommt häufig in Verbindung mit Arsen vor und bildet als Arsenkobalt das häufigste Kobalterz, den Speiskobalt. Speiskobalt war ein wichtiges Kobalterz zur Blaufarbenbereitung in der Porzellanindustrie. In Anbetracht der Toxizität von Arsen, einschließlich seiner kanzerogenen Wirkung, sowie des zeitlichen und örtlichen Zusammenhangs zwischen der ausgeübten Tätigkeit der Patientin und der Entstehung des Plattenepithelkarzinoms konnten wir bei dem vorliegenden Fall den Verdacht auf eine Berufskrankheit Nr. 1108 (nach Berufskrankheiten-Verordnung) äußern.
Rheumatoide Arthritis – die neuen Therapieoptionen
Authors: Fiehn Christoph
Published: December 2017

Was ist neu?

Die JAK-Inhibitoren Die Janus-Kinase (JAK)-Inhibitoren Tofacitinib und Baricitinib sind 2017 neu zur Behandlung der rheumatoiden Arthritis (RA), nach Versagen oder Unverträglichkeit von konventionellen krankheitsmodifizierenden Antirheumatika (disease modifying antirheumatic drugs; DMARD), zugelassen. Sie wirken intrazellulär durch Hemmung der JAK-Kinasen und verhindern so die Weiterleitung der aktivierenden Signale von Zytokinrezeptoren auf inflammatorische Zellpopulationen. Die JAK-Inhibitoren reduzieren effektiv die Krankheitsaktivität der RA, verbessern die körperliche Funktion und reduzieren die strukturellen Veränderungen der Gelenke. In Vergleichsstudien gegenüber dem TNF-alpha-Hemmstoff Adalimumab haben sie eine gleich gute, im Fall von Baricitinib sogar eine leicht überlegene Wirksamkeit gezeigt. Die Infektionsrate ist unter einer Therapie mit JAK-Inhibitoren im Vergleich zu konventionellen DMARD erhöht.

Neuer Interleukin-6-Hemmstoff Das schon länger bewährte Wirkprinzip der Hemmung von Interleukin(IL)-6 wird nun durch den neuen Wirkstoff Sarilumab ergänzt. Die Substanz wirkt effektiv auf die Krankheitsaktivität, die körperliche Funktion und die radiologisch sichtbaren strukturellen Veränderungen der RA. Darüber hinaus reduziert sie die systemischen Symptome der Erkrankung.
Rethinking policy ‘impact’: four models of research-policy relations
Authors: Boswell Christina , Smith Katherine
Published: December 2017

Political scientists are increasingly exhorted to ensure their research has policy ‘impact’, most notably via Research Excellence Framework (REF) impact case studies, and ‘pathways to impact’ statements in UK Research Council funding applications. Yet the assumptions underpinning these frameworks often fail to reflect available evidence and theories. Notions of ‘impact’, ‘engagement’ and ‘knowledge exchange’ are typically premised on simplistic, linear models of the policy process, according to which policy-makers are keen to ‘utilise’ expertise to produce more ‘effective’ policies. Such accounts overlook the rich body of literature in political science, policy studies, and sociology of knowledge, which offer more complex and nuanced accounts. Drawing on this wider literature, this paper sets out four different approaches to theorising the relationship: (1) knowledge shapes policy; (2) politics shapes knowledge; (3) co-production; and (4) autonomous spheres. We consider what each of these four approaches suggests about approaches to incentivising and measuring research impact.