bluuebunny/crossref_metadata_2025 huggingface dataset:
Coordinated G&TEP and carbon capture and storage expansion planning model for emission constrained power systems
Authors: Asgharian Vahid , Abdelaziz Morad , Kamwa Innocent
Published: February 2021

Fossil fuel‐fired power plants are still the principal power producers in most power systems. Retrofitting these pollutant generators with carbon capture and storage (CCS) technology can be a key solution to decarbonisation, especially for power systems with low expansion potential for renewable and hydroelectric energy resources. This study presents a coordinated generation and transmission expansion planning (G&TEP) and CCS expansion planning model for carbon emission constrained power systems. The proposed model determines the optimal order and time of retrofitting carbon emitter generators with CCS technology coordinated with the G&TEP. The limits on renewable resources capacity expansion potential and the yearly emission reduction targets are considered. Additionally, the proposed model allows for determining the incentives that are to be offered by the central planning authority to the pollutant generators to incentivise their participation in emission reduction through CCS retrofitting. The problem is formulated as a mixed‐integer linear programming model and is decomposed into a master and three subproblems to tackle the large‐scale nature of the developed optimisation problem. Numerical results demonstrate that a coordinated G&TEP and CCS expansion planning is a least‐cost planning solution for emission constrained power systems with low expansion capacity potential for renewable and hydroelectric resources.
Novel hybrid signal processing approach based on empirical mode decomposition and multiscale mathematical morphology for islanding detection in distributed generation system
Authors: Nayak Pravati , Kumar Mallick Ranjan , Dhar Snehamoy
Published: February 2021

A novel islanding detection technique by hybridising empirical mode decomposition (EMD) and multi‐scale mathematical morphology (MMM) is proposed to detect the islanding condition in a distributed generation system to ensure personnel and equipment safety. The proposed method first uses EMD to efficiently separate the collected raw signal into the number of intrinsic mode functions (IMFs) with different frequency scales and the signal is reconstructed considering important IMFs which carry transient features for further analysis using their correlation coefficients. MMM is used for determining a ratio index named as MMMRI, the threshold value of the proposed MMMRI decides islanding and other power quality (PQ) disturbances. The proposed hybrid method name coined as EMD‐MMMRI. The main motivation behind hybridising two signal processing techniques is to reduce detection time and improve accuracy. The efficacy of the method is demonstrated for different PQ disturbances and islanding events simulated on a grid‐connected, heavily wind energy penetrated distributed generation system using MATLAB/Simulink environment. The test bench validation of the proposed technique is obtained through TMS 320C6713 Starter Kit (DSK) in digital signal processor platform. The efficacy of proposed work is demonstrated with large number of simulation studies.
Risk assessment by security‐constrained unit commitment for hybrid wind‐thermal by pair copula approach in reserve power market: a stochastic approach
Authors: Panda Rajesh , Tiwari Prashant Kumar
Published: February 2021

High volatility renewable penetration increases the security risk of the market participants. In order to ensure the security of the reserve market under uncertainties, the authors have proposed a novel optimal bidding strategy based on bivariate pair copula‐based security‐constrained unit commitment economic dispatch (SCUCED) for the generation companies (GENCOs) while considering the volatility of wind power generations and load variations under different (N − k) contingencies in ancillary service market. The expected profit of GENCOs are based on the ramp‐up and ramp‐down optimal reserve curves in each time interval are submitted to the independent system operator. The profit of wind farms is obtained and the risks due to uncertainties with wind farms are also analysed while participating in the reserve market. Conditional value‐at‐risk is considered for the optimal placement of wind farms in the network. The risk‐based SCUCED model is solved by mixed integer linear programming. Moreover, a factor called joint Pareto tail factor has been also developed to provide information regarding the fat tails in the lower end of the bivariate marginal distribution of different GENCOs. The effectiveness of the proposed approach has been tested on a modified IEEE 30 bus system.
Cracking risk analysis and control for high‐voltage dry‐type valve‐side bushings
Authors: Chen Ming , Liu Xuandong , Shao Yuhang , Tang Hao , Wu Zhicheng , Zhang Qiaogen , Li Jinzhong
Published: February 2021

The temperature gradient and mismatching between the thermal expansion of the core and flange readily lead to cracks and discharges on the core surface of the dry‐type valve‐side bushing, which severely impact the safety of power systems. It is vital to clarify the cracking risk of bushing cores under temperature gradients and establish corresponding control methods. The mechanical properties of epoxy resin impregnated paper (ERIP) material were measured in this study at different temperatures, and a thermal–mechanical coupling simulation model was established. The thermal and stress distributions of the core were obtained and the cracking risk was defined accordingly. The crack development mode was explored as it relates to the phase‐field mode. Various elastic cushion materials affecting the stress distribution of the core were investigated. The results show that the mechanical properties of the ERIP material decrease rapidly as the temperature increases. When under severe working conditions, the maximum first principal stress of the core may be significantly higher than the tensile strength of the ERIP material resulting in significant axial cracks. Adding an elastic cushion layer made of polyurethane rubber can effectively relax the interface stress and reduce the cracking risk.
Measurements and characterisation of low and medium voltage residential, commercial, and industrial NB‐PLC networks for AMI
Authors: Masood Bilal , Guobing Song , Baig Sobia , Rasheed Muhammad Babar , Hou Junjie
Published: February 2021

This study investigates the feasibility of advanced metering infrastructure (AMI) based on narrowband power line communications (NB‐PLC) by incorporating all possible types of low voltage (LV) and medium voltage (MV) power line channels. The extensive field measurements are carried out on six selected sites that include residential, commercial, and industrial LV and MV NB‐PLC channels. On the basis of measured results, NB‐PLC channels of various under evaluation sites are segregated into two classes i.e. worst and good channels for both LV and MV networks. The simulation models for the modelling of LV and MV NB‐PLC channels by considering the practical data of measured sites are developed and thus proposed. The proposed methods are validated by comparing the measured and simulated results. A sophisticated mechanism for the modelling of LV and MV network impedances and capacitive coupling device is formulated. The proposed analyses and simulation‐based NB‐PLC channel models can play a key role in examining the characteristics of various types of NB‐PLC channels. This research work will help to standardise the future smart metering equipment and sensing devices of power system protection.
Stabilising transient disturbances with utility‐scale inverter‐based resources
Authors: Elliott Ryan T. , Arabshahi Payman , Kirschen Daniel S.
Published: February 2021

This study presents a trajectory tracking control strategy that modulates the active power injected by geographically distributed inverter‐based resources to support transient stability. Each resource is independently controlled, and its response drives the local bus voltage angle towards a trajectory that tracks the angle of the centre‐of‐inertia. The centre‐of‐inertia angle is estimated in real time from wide‐area measurements. The main objectives are to stabilise transient disturbances and increase the amount of power that can be safely transferred over key transmission paths without loss of synchronism. Here the authors envision the actuators as utility‐scale energy storage systems; however, equivalent examples could be developed for partially‐curtailed photovoltaic generation and/or Type 4 wind turbine generators. The strategy stems from a time‐varying linearisation of the equations of motion for a synchronous machine. The control action produces synchronising torque in a special reference frame that accounts for the motion of the centre‐of‐inertia. This drives the system states toward the desired trajectory and promotes rotor angle stability. For testing, a reduced‐order dynamic model of the North American Western Interconnection is employed. The results show that this approach improves system reliability and can increase capacity utilisation on stability‐limited transmission corridors.
Non‐linear deadbeat direct torque and flux control for switched reluctance motor
Authors: Li Qianni , Xu Aide , Shang Chaoyi , Zhu Jingwei , Zhou Lifang
Published: February 2021

In this study, the non‐linear deadbeat direct torque and flux control (N‐DB‐DTFC) scheme is proposed for switched reluctance motor (SRM) to achieve torque and flux precise control. For torque control part, the Fourier series form of inductance is used to establish the non‐linear torque model of SRM. As for the flux control, stator flux‐oriented is adopted to achieve the flux control and simplified calculation in N‐DB‐DTFC. In addition, the synthetic voltage vectors are applied by pulse‐width modulation. In order to assess the performance of N‐DB‐DTFC, the comparison of torque ripple is analysed among the traditional deadbeat controls in the simulation and experiment. Although, for the torque transient response, three deadbeat controls show the strong robustness and adaptability. In the results, the proposed N‐DB‐DTFC strategy shows better reflection in terms of lower torque ripple. Moreover, the results of simulation and experiment are based on a three‐phase 12/8‐poles SRM.
Single DC source diode‐assisted hybrid multilevel inverter using a reduced number of active and passive components
Authors: Motwani Jayesh K. , Routray Abhinandan , Singh Rajeev K. , Mahanty Ranjit
Published: February 2021

In this study, a seventeen‐level diode‐assisted hybrid multilevel inverter (DAH‐MLI) is proposed. The DAH‐MLI eliminates any external voltage balancing and/or sensing circuit by inherently balancing the capacitors using a series–parallel combination of capacitors and DC voltage source. The DAH‐MLI uses only one DC source and a reduced number of active and passive elements to generate a multilevel staircase output voltage. The proposed circuit can also be extended to obtain the higher number of voltage levels than seventeen by the addition of a single module comprising of two diodes, one switch, and one capacitor. The proposed DAH‐MLI can boost the input voltage and possesses reverse current carrying capability. The proposed DAH‐MLI is compared with several existing topologies on the basis of the number of active and passive components, total standing voltage, and peak inverse voltage to verify its advantages. A cost function is used in this study to compare the proposed DAH‐MLI and other existing typologies. Finally, the performance of the proposed DAH‐MLI is validated through a 570 W experimental prototype.
Voltage source boost multilevel inverter with high modularity: circuit configuration and modulation
Authors: Sabour Shahin , Hassanifar Mahyar , Choupan Reza , Golshannavaz Sajjad , Neyshabouri Yousef , Nazarpour Daryoush
Published: February 2021

This study introduces a boost multilevel inverter (MLI) based on a switched capacitor structure. The proposed inverter features high modularity as a result of which more levels and ratings of voltage can be obtained in the inverter AC terminals. The extension of this topology in both symmetric and asymmetric configurations are introduced and analysed. Taking advantage of the switched‐capacitor technique, only one DC source is utilised while the voltages of several capacitors are kept balanced without the adoption of any sophisticated balancing algorithm. A combination of two basic submodules named as boost switched capacitor submodule and dual switched capacitor submodule forms the proposed structure. Compared to the existing alternatives, the proposed one provides more voltage levels with a lower number of power switches and input DC sources. The performance of the presented MLI is verified through the MATLAB/Simulink environment. Finally, the experimental results are presented, validating the feasibility and effectiveness of the studied inverter.
Getting to 100% renewables: operating experiences with very high penetrations of variable energy resources
Authors: Lew Debra , Bartlett Drake , Groom Andrew , Jorgensen Peter , O'Sullivan Jon , Quint Ryan , Rew Bruce , Rockwell Brad , Sharma Sandip
Published: February 2021

This study examines experiences of grid operators to successfully integrate very high penetrations of wind and solar photovoltaic (PV) resources. The variability of these resources creates challenges in balancing the system generation and demand, and ensuring resource adequacy and essential reliability services. The inverter‐based nature of wind and solar PV leads to challenges in frequency, transient, and small‐signal stability. In this study, seven system operators demonstrate the ability to manage these challenges in a variety of power systems, from stand‐alone island systems to larger island systems that are interconnected to neighbours, to balancing authorities that are strongly interconnected within very large synchronous systems. They operate within a variety of market constructs, from full regional transmission operators to vertically‐integrated utilities. All are experiencing increases in the penetration of inverter‐based, variable energy resources and finding creative solutions to these challenges.
Robust wideband adaptive beamforming based on covariance matrix reconstruction in the spatial‐frequency domain
Authors: Lu Jian , Yang Jian , Yao Zhicheng , Zhu Fengchao , Yu Zhiyong , Liu Guangbin
Published: February 2021

Without the response variation constraint, the main‐lobe responses of wideband beamforming usually vary with the frequencies of interest, and the beam pointing may deviate from the incident angle of the desired signal. If the interference‐plus‐noise covariance matrix (INCM) is directly replaced by the sample covariance matrix, the desired signal in the sample data may result in self‐null problem, which can lead to the degradation of the performance of wideband beamformers. Through frequency division, a novel wideband adaptive beamforming is proposed by reconstructing the INCM and solving the convex optimisation problem. Using fast Fourier transform (FFT), the time‐domain samples are transformed into the frequency field, and the covariance matrix of each subband can be obtained from the frequency‐domain data. In the spatial‐frequency domain, the INCM and signal‐plus‐noise covariance matrix can be respectively reconstructed by integrating the stacked steering vector and the Capon spatial spectrum over the corresponding angular region. Then, we establish the optimisation criteria, that is, minimising the output interference‐plus‐noise power, minimising the main‐lobe spatial response variation, and constraining the response deviation of the desired signal. A novel convex optimisation model can be established, and then the weight coefficients for time‐domain wideband beamforming can be obtained by solving the optimisation problem. The simulation and experimental results demonstrate that the proposed beamformer can provide better performance compared with other tested beamformers and maintain good robustness in various applications.
On‐chip test method for in‐situ evaluating the impact resistance reliability of silicon microbeams
Authors: Cheng Leijian , Zhang Dacheng
Published: February 2021

To the best of the authors’ knowledge, this Letter reports and validates for the first time an on‐chip reseTable test method that can be used to in‐situ evaluate the impact reliability of a process‐related silicon microbeam. A test structure integrating impact generating device, test samples, and a lock module is proposed to evaluate the impact‐resistant reliability of the process‐related microbeam samples with only a common optical microscope and probe station in the fabrication line. A calculation model that uses the LS‐Dyna module in the finite‐element commercial software ANSYS to process the test results is proposed to obtain the numerical parameters of the impact resistance reliability of the microbeam specimen. The test structure can be manufactured using a variety of mainstream MEMS silicon processes, so it can characterise the impact reliability of silicon microbeam structures under various processes. The above three parts constitute a self‐aligned, low‐cost test method with automation potential, which can be used for large‐scale characterisation of the impact resistance reliability of silicon microbeam structures on the fabrication line. Finally, beam specimens under three different process conditions were manufactured and successfully evaluated using this test method, which verified the rationality of this method.
Pyramid textured Si{100} surface with low reflectivity in CMOS compatible solution
Authors: Gupta Arti , Pal Prem , Sharma Chandra Shekhar
Published: February 2021

Wet anisotropic etching of Si{100} results in micro‐pyramids/hillocks bounded by four {111} planes. These kinds of geometrical structures are needed to reduce the front surface reflectance from silicon by taking multiple internal reflections of the incident ray and thus increase the efficiency of the solar cells. In this work, surface texturing of Si{100} is performed at different temperatures in a very low concentration CMOS compatible tetramethylammonium hydroxide (TMAH) without using any additive and agitation. The present research is aimed to significantly reduce the etching time in an extremely low concentration TMAH to texture the silicon surface for obtaining the lowest possible reflectance. Etching temperature is varied from 80 to 95°C with a step of 5°C. For each temperature, the etching time is also varied from 5 to 40 min with an interval of 5 min, whereas etching concentration is made a fix to 0.5 wt%. Surface morphology with dense and uniform pyramidal structures is achieved on the silicon samples etched at 85°C for 25 min. These samples provide the average solar weighted reflectance (Rsw) of around 10% and the lowest reflectance of 6.7% at 790 nm.
Design, takeoff and steering torques modulation of an 80‐mg insect‐scale flapping‐wing robot
Authors: Wang Chenyang , Zhang Weiping , Zhao Jiaxin , Hu Junqi , Zou Yang
Published: February 2021

An 80‐mg double piezo‐actuated insect‐inspired flapping‐wing robot is presented in this Letter. With the design of the two piezoelectric actuators placed back to back, each wing of this robot is independently driven and controlled, giving this robot the ability to achieve asymmetric flapping of the two wings to generate torques for steering. The piezoelectric actuators are designed with electrical insulation and structural reinforcement to improve the reliability under high‐voltage and high‐frequency drive mode. Fibre directions of each component of the robot are reasonably designed to enhance strength and stiffness. The average lift generated by the robot is measured by a customised lift measurement system found to be proportional to the square of the input voltage amplitude. The three steering torques generated by the robot are measured separately by a customised lift measurement system. Each steering torque can only be linearly modulated by its specific control variable of the input voltages. With a total weight of 80 mg and a wingspan of 3.5 cm, this robot can generate sufficient lift to take off and independently modulate all three steering torques with good decoupling, which is vital for the further controlled flight.
The DOA location deception effect of frequency diverse array on interferometer
Authors: Ge Jiaang , Xie Junwei , Wang Bo , Chen Chushu
Published: February 2021

With advances in radar localisation, especially the emergence and development of passive localisation, there is an urgent demand for countermeasure technology. To counteract the passive direction‐of‐arrival (DOA) location, this article studies the DOA location deception effect of a frequency diverse array (FDA) on an interferometer. By analysing the phase distribution model of the uniform linear FDA (ULFDA) signal and the DOA location principle of the one‐dimensional phase interferometer, it was found that the phase difference the FDA produces does not conform to the direction‐finding law of the interferometer, which provides a potential capability for the FDA to achieve localisation deception for the interferometer. Based on the proposed DOA location deception model and the instantaneous signal‐to‐noise‐ratio (ISNR), the CRLB and RMSE of the angle and x‐intercept deviation are investigated. The results show that, compared with conventional phased array signals, the FDA signal can achieve DOA location deception on the interferometer, and by properly configuring the frequency increment sequence, the FDA can perform better DOA location deception on the interferometer, which means that the FDA provides promising potential for radar security.
Machine learning technique for morphological classification of galaxies from the SDSS
Authors: Vavilova I. B. , Dobrycheva D. V. , Vasylenko M. Yu. , Elyiv A. A. , Melnyk O. V. , Khramtsov V.
Published: February 2021

Context. Machine learning methods are effective tools in astronomical tasks for classifying objects by their individual features. One of the promising utilities is related to the morphological classification of galaxies at different redshifts.

Aims. We use the photometry-based approach for the SDSS data (1) to exploit five supervised machine learning techniques and define the most effective among them for the automated galaxy morphological classification; (2) to test the influence of photometry data on morphology classification; (3) to discuss problem points of supervised machine learning and labeling bias; and (4) to apply the best fitting machine learning methods for revealing the unknown morphological types of galaxies from the SDSS DR9 at z < 0.1.

Methods. We used different galaxy classification techniques: human labeling, multi-photometry diagrams, naive Bayes, logistic regression, support-vector machine, random forest, k-nearest neighbors.

Results. We present the results of a binary automated morphological classification of galaxies conducted by human labeling, multi-photometry, and five supervised machine learning methods. We applied it to the sample of galaxies from the SDSS DR9 with redshifts of 0.02 < z < 0.1 and absolute stellar magnitudes of −24m < Mr < −19.4m. For the analysis we used absolute magnitudes Mu, Mg, Mr, Mi, Mz; color indices Mu − Mr, Mg − Mi, Mu − Mg, Mr − Mz; and the inverse concentration index to the center R50/R90. We determined the ability of each method to predict the morphological type, and verified various dependencies of the method’s accuracy on redshifts, human labeling, morphological shape, and overlap of different morphological types for galaxies with the same color indices. We find that the morphology based on the supervised machine learning methods trained over photometric parameters demonstrates significantly less bias than the morphology based on citizen-science classifiers.

Conclusions. The support-vector machine and random forest methods with Scikit-learn software machine learning library in Python provide the highest accuracy for the binary galaxy morphological classification. Specifically, the success rate is 96.4% for support-vector machine (96.1% early E and 96.9% late L types) and 95.5% for random forest (96.7% early E and 92.8% late L types). Applying the support-vector machine for the sample of 316 031 galaxies from the SDSS DR9 at z < 0.1 with unknown morphological types, we found 139 659 E and 176 372 L types among them.
Detection of new O-type stars in the obscured stellar cluster Tr 16-SE in the Carina Nebula with KMOS
Authors: Preibisch T. , Flaischlen S. , Göppl C. , Ercolano B. , Roccatagliata V.
Published: February 2021

Context.The Carina Nebula harbors a large population of high-mass stars, including at least 75 O-type and Wolf-Rayet (WR) stars, but the current census is not complete since further high-mass stars may be hidden in or behind the dense dark clouds that pervade the association.

Aims.With the aim of identifying optically obscured O- and early B-type stars in the Carina Nebula, we performed the first infrared spectroscopic study of stars in the optically obscured stellar cluster Tr 16-SE, located behind a dark dust lane south ofηCar.

Methods.We used the integral-field spectrograph KMOS at the ESO VLT to obtainH- andK-band spectra with a resolution ofR ≈ 4000 (Δλ≈ 5 Å) for 45 out of the 47 possible OB candidate stars in Tr 16-SE, and we derived spectral types for these stars.

Results.We find 15 stars in Tr 16-SE with spectral types between O5 and B2 (i.e., high-mass stars withM ≥ 8 M⊙), only two of which were known before. An additional nine stars are classified as (Ae)Be stars (i.e., intermediate-mass pre-main-sequence stars), and most of the remaining targets show clear signatures of being late-type stars and are thus most likely foreground stars or background giants unrelated to the Carina Nebula. Our estimates of the stellar luminosities suggest that nine of the 15 O- and early B-type stars are members of Tr 16-SE, whereas the other six seem to be background objects.

Conclusions.Our study increases the number of spectroscopically identified high-mass stars (M ≥ 8 M⊙) in Tr 16-SE from two to nine and shows that Tr 16-SE is one of the larger clusters in the Carina Nebula. Our identification of three new stars with spectral types between O5 and O7 and four new stars with spectral types O9 to B1 significantly increases the number of spectroscopically identified O-type stars in the Carina Nebula.
Transition from coherent cores to surrounding cloud in L1688
Authors: Choudhury Spandan , Pineda Jaime E. , Caselli Paola , Offner Stella S. R. , Rosolowsky Erik , Friesen Rachel K. , Redaelli Elena , Chacón-Tanarro Ana , Shirley Yancy , Punanova Anna , Kirk Helen
Published: February 2021

Context. Stars form in cold dense cores showing subsonic velocity dispersions. The parental molecular clouds display higher temperatures and supersonic velocity dispersions. The transition from core to cloud has been observed in velocity dispersion, but temperature and abundance variations are unknown.

Aims. We aim to measure the temperature and velocity dispersion across cores and ambient cloud in a single tracer to study the transition between the two regions.

Methods. We use NH3 (1,1) and (2,2) maps in L1688 from the Green Bank Ammonia Survey, smoothed to 1′, and determine the physical properties by fitting the spectra. We identify the coherent cores and study the changes in temperature and velocity dispersion from the cores to the surrounding cloud.

Results. We obtain a kinetic temperature map extending beyond dense cores and tracing the cloud, improving from previous maps tracing mostly the cores. The cloud is 4–6 K warmer than the cores, and shows a larger velocity dispersion (Δσv = 0.15–0.25 km s−1). Comparing to Herschel-based dust temperatures, we find that cores show kinetic temperatures that are ≈1.8 K lower than the dust temperature, while the gas temperature is higher than the dust temperature in the cloud. We find an average p-NH3 fractional abundance (with respect to H2) of (4.2 ± 0.2) × 10−9 towards the coherent cores, and (1.4 ± 0.1) × 10−9 outside the core boundaries. Using stacked spectra, we detect two components, one narrow and one broad, towards cores and their neighbourhoods. We find the turbulence in the narrow component to be correlated with the size of the structure (Pearson-r = 0.54). With these unresolved regional measurements, we obtain a turbulence–size relation of σv,NT ∝ r0.5, which is similar to previous findings using multiple tracers.

Conclusions. We discover that the subsonic component extends up to 0.15 pc beyond the typical coherent boundaries, unveiling larger extents of the coherent cores and showing gradual transition to coherence over ~0.2 pc.
IRIS observations of chromospheric heating by acoustic waves in solar quiet and active regions
Authors: Abbasvand V. , Sobotka M. , Švanda M. , Heinzel P. , Liu W. , Mravcová L.
Published: February 2021

Aims. To study the heating of solar chromospheric magnetic and nonmagnetic regions by acoustic and magnetoacoustic waves, the deposited acoustic-energy flux derived from observations of strong chromospheric lines is compared with the total integrated radiative losses.

Methods. A set of 23 quiet-Sun and weak-plage regions were observed in the Mg II k and h lines with the Interface Region Imaging Spectrograph (IRIS). The deposited acoustic-energy flux was derived from Doppler velocities observed at two different geometrical heights corresponding to the middle and upper chromosphere. A set of scaled nonlocal thermodynamic equilibrium 1D hydrostatic semi-empirical models – obtained by fitting synthetic to observed line profiles – was applied to compute the radiative losses. The characteristics of observed waves were studied by means of a wavelet analysis.

Results. Observed waves propagate upward at supersonic speed. In the quiet chromosphere, the deposited acoustic flux is sufficient to balance the radiative losses and maintain the semi-empirical temperatures in the layers under study. In the active-region chromosphere, the comparison shows that the contribution of acoustic-energy flux to the radiative losses is only 10−30%.

Conclusions. Acoustic and magnetoacoustic waves play an important role in the chromospheric heating, depositing a main part of their energy in the chromosphere. Acoustic waves compensate for a substantial fraction of the chromospheric radiative losses in quiet regions. In active regions, their contribution is too small to balance the radiative losses and the chromosphere has to be heated by other mechanisms.
Anatomy of Perforating veins of the lower limb
Authors: Uhl Jean-François , Gillot Claude
Published: February 2021

Die Perforansvenen (PV) der unteren Extremitäten sind nicht nur gerade und direkte Verbindungen zwischen den tiefen und oberflächlichen Venennetzen, sondern bilden gemeinsam ein weit verzweigtes Netz. Trotz ihrer starken anatomischen Variabilität ist ihre Position bemerkenswert konstant und prognostizierbar. Dies ist durch ihre enge Beziehung zu den Muskelvenen bedingt und durch die hämodynamischen Ebenen entlang der Extremität zu erklären. Sie sind bei der Beurteilung durch Ultraschalluntersucher in der täglichen Praxis eine Hilfe.

Der anatomische Inhalt dieses Artikels stammt aus folgenden Quellen: Anatomische Präparationen von C. Gillot nach Latex-Injektion und anschließender farblicher Unterteilung von über 400 Extremitäten. Dreidimensionale Rekonstruktionen von CT-Venografien von 1200 Extremitäten und präoperativen Hautvenenvermessungen von 25 000 Extremitäten.

Es wird Folgendes beschrieben: Referenzpunkte der Extremität, Perforansvenen des Fußes, Beins und Sprunggelenks, der Wade, Anastomosen zwischen den Perforansvenen, Begleitarterien der Bein-PVs und Oberschenkel-PVs.
Ummantelung und Schutz
Authors: Corts Magga
Published: February 2021

Gehirn und Rückenmark – also das zentrale Nervensystem (ZNS) – sind von strukturierten bindegewebigen Schichten umgeben, den Meningen (Einzahl: Meninx). Je nach Ort und Topografie gibt es bauliche Unterschiede der Meningen.
Prüfungsthema: Grundsätze in der Heilpraktikerpraxis
Authors: Schmid Eva C.
Published: February 2021

In diesem HPA-Prüfungstrainer beschäftigen sich alle Fragen mit Grundsätzen in der Heilpraktikerpraxis.
Skin Color May Predict Intra-Abdominal Adhesions During Repeated Caesarean Section Deliveries
Authors: Altınboğa Orhan , Karakoç Gökhan , Eroğlu Hasan , Akpınar Funda , Erol Seyit Ahmet , Yakıştıran Betül , Tekin Özlem Moraloğlu , Yucel Aykan
Published: February 2021

Objective Caesarean rates have increased rapidly for various reasons recently. One of the important reasons among these is medicolegal problems. Our aim with this study was to preoperatively predict abdominal adhesion density by combining the scar tissue morphology formed in the post-caesarean Pfannenstiel incision line and the skin color scoring of the patients.

Material and methods Patients who had undergone one caesarean section previously, completed their terms (37−39 weeks) and were under 35 years old were included in the study. Skin color scoring of the patients was performed using the Fitzpatrick skin color scale. Intra-abdominal adhesion scoring of the participant patients was performed using Nair’s adhesion scoring system.

Results The change in abdominal adhesion scores was evaluated based on the Fitzpatrick color scale. Adhesion scores per the Nair intra-abdominal adhesion scoring system were found to be 0.04±0.209 in the FP1 group, 0.35±0.662 in the FP2 group, 1.58±0.923 in the FP3 group, and 2.33±0.577 in the FP4 group (p<0.05). These results showed a significant increase in adhesion density with increasing skin color darkness. Based on these results, it was observed that the abdominal adhesion scores and the frequency of depressed skin scar were significantly increased with increasing Fitzpatrick scores (p<0.05).

Conclusion The aim of this study was to increase the prediction rates by adding the skin color scoring to the scar tissue characteristics, which have been used in previous studies. The results of this study indicate that the combination of these two parameters may be more effective in predicting intra-abdominal adhesions. Nevertheless, there is a need for studies with a much higher number of patients and multiple parameters to be able to predict intra-abdominal adhesion density preoperatively with greater accuracy.
Erstellung zuverlässiger Erythrozytenkonzentrat-Bedarfslisten für Operationen und Interventionen aus Data-Warehouse-Daten und der patientenbezogenen Chargendokumentation von Blutkomponenten
Authors: Zimmermann Robert , Becker Andreas , Hackstein Holger , Ganslandt Thomas
Published: February 2021

Das Versäumnis, transfusionsvorbereitende Diagnostik durchzuführen und eine ausreichende Anzahl von Blutkomponenten vor der Operation zu bestellen, führt zunehmend zu klinischen Notfällen und vermeidbaren Risiken für die Patienten. Die eigentlich obligatorische Erstellung von Blutbedarfslisten scheitert oft an der Verfügbarkeit geeigneter Daten. Das Universitätsklinikum Erlangen ist ein Krankenhaus der Tertiärversorgung mit 1400 Betten. Hier werden seit 2010 kontinuierlich alle relevanten Daten zur Interpretation von Mustern bei der Verwendung von Blutbestandteilen erhoben. Wir sind in der Lage, die klinischen Data-Warehouse-Komponenten der persönlichen Daten der Empfänger von Erythrozytenkonzentraten (EK), die Codes der stationären Patienten im G-DRG-System (G-DRG: German Diagnosis Related Group), ICD-Codes, OPS-Codes und die Daten der EK-Komponenten aus dem IT-System der Blutbank zu integrieren. Die erhaltenen DRGs, ICD-Codes und OPS-Codes werden mit den Daten des
Blutkomponentenverbrauchs auf individueller Basis verknüpft. Analysen können sowohl im gesamten Krankenhaus als auch in Bezug auf bestimmte Abteilungen durchgeführt werden. Die laufende Verfeinerung der Datenbankabfragen verbessert die Fähigkeit, den Blutbedarf für Standardoperationen und Interventionen korrekt abzuschätzen. Die Ergebnisse weichen zum Teil erheblich von den Schätzungen der Operateure hinsichtlich der Wahrscheinlichkeit einer Transfusion ab, oftmals wird die Wahrscheinlichkeit einer Transfusion unterschätzt. Die korrekte Einhaltung der 10-prozentigen Transfusionswahrscheinlichkeitsgrenze für die Frage der frühen präoperativen Bereitstellung von Kreuzblut kann durch solche Abfragen verbessert werden. Dem Phänomen der „verzögerten Transfusion“ entgegenzuwirken, wird zu einer immer wichtigeren Aufgabe für den klinisch tätigen transfusionsmedizinischen Arzt. Die Erstellung von Statistiken über die Transfusionswahrscheinlichkeit durch die Verknüpfung von
Data-Warehouse-Daten und Chargendokumentationsdaten aus Blutbanken kann die notwendigen Werkzeuge bereitstellen.
Neues Cover-Design, fortgesetzte Mindestmengen-Diskussion
Authors: Singer Dominique
Published: February 2021

Liebe Leserinnen und Leser,

das vorliegende Heft der Zeitschrift für Geburtshilfe und Neonatologie (ZGN) erscheint im neuen Design, mit einem graphischen Cover-Motiv, das uns übers Jahr in 6 verschiedenen Kolorierungen begleiten wird. Ein unbeabsichtigter Zufall ist es, dass just in diesem Heft eine Originalarbeit mit dem Titel „Skin color may predict intra-abdominal adhesions during repeated caesarean section deliveries“ erscheint. Die in dieser Arbeit benutzten „Fitzpatrick skin color scales“ beziehen sich übrigens, um etwaigen Missverständnissen zuvorzukommen, nicht auf die „Hautfarbe“ im Sinne der Ethnizität, sondern vielmehr auf den „Hauttyp“ und dienen ursprünglich der dermatologischen Einschätzung der UV-Empfindlichkeit (bzw. der – sich umgekehrt proportional zur Bräunungsneigung verhaltenden – Sonnenbrandgefährdung).
Fibrin glue: Novel submucosal injection agent for endoscopic submucosal dissection
Authors: Takao Madoka , Takegawa Yoshitaka , Takao Toshitatsu , Sakaguchi Hiroya , Nakano Yoshiko , Tanaka Shinwa , Morita Yoshinori , Toyonaga Takashi , Umegaki Eiji , Kutsumi Hiromu , Kodama Yuzo
Published: February 2021

Background and study aims Adequate mucosal elevation by submucosal injection is crucial for patient safety and efficiency during endoscopic submucosal dissection (ESD). This study aimed to evaluate the efficacy of fibrin glue (FG) as a long-lasting submucosal injection agent and to evaluate the technical feasibility of FG injection for ESD.

Materials and methods To compare the capabilities of different agents in maintaining submucosal evaluation, we injected FG, hyaluronic acid solution, and normal saline into the porcine gastric specimen that was incised into approximately 5 × 5 cm squares. Then, we measured the height of submucosal elevations over time. Moreover, three hypothetical lesions from the resected porcine stomach underwent ESD with FG injection. Thereafter, we conducted macroscopic and histopathologic analyses.

Results FG maintained the greatest submucosal elevation among all the injection agents. Three ESD procedures were performed with en bloc resection. Both macroscopic and histopathologic findings showed a thick FG clot on the ulcers.

Conclusions The FG solution can be potentially used as an ESD submucosal injection agent in an in vitro model.
Endoscopic ultrasound-guided colo-colostomy in a case of acute large bowel obstruction
Authors: Emmanuel James , Kollanthavelu Sattian , Henry Fitjerald , See Lee Tiong
Published: February 2021

Bowel obstruction is one of the most common surgical emergencies and a major cause of morbidity and mortality. Standard supportive measures must be instituted as soon as the diagnosis is confirmed. Anastomotic strictures are a benign etiology of intestinal obstruction, occurring in up to 22 % of patients following colorectal resection. Traditionally, endoscopic balloon dilation (EBD) has been the intervention of choice in such cases; however, it may not be feasible in all settings. We report a novel application of the AXIOS stent and electrocautery-enhanced delivery system (Boston Scientific, Marlborough, Massachusetts, United States) to create a colo-colostomy to bypass a sigmoid colon stricture in a 51-year-old woman who presented with acute intestinal obstruction. Despite stent dislodgment during the procedure, the preexisting tract allowed us to improvise our technique with a second LAMS placement. The patient was discharged well 48 hours after the procedure. However, 4 months later, she required a session of EBD following a presentation for fecal impaction. She is currently asymptomatic and being followed up regularly as an outpatient.
Acute Ischemic Stroke in a 10-Month-Old Baby Recovered With Aspirin
Authors: Hosseini Seyed A. , Gharib Mohammad H. , Mirheidari Seyed B. , Ghanbarzade Bahar , Hosseini Parnian S.
Published: February 2021

Acute ischemic stroke is rare in children and often brings enduring and permanent morbidity in pediatric population. While there are numerous recommendations for initial treatment, evidence on effectiveness of different therapies among children is limited. Here, we describe a 10-month-old male child patient who presented with fever, restlessness, seizure and postictal left limb weakness. Examination revealed left hemiplegia and hemiparesthesia. Computed tomography (CT) head showed loss of gray–white matter distinction with diffuse hypodensity in the right temporoparietal lobes and right caudate nucleus. Magnetic resonance imaging (MRI) brain demonstrated diffusion restriction in favor of acute ischemic stroke in the right middle cerebral artery (MCA) territory. Brain MR angiography (MRA) demonstrated complete occlusion of proximal aspect of M1 segment of right MCA. Genetic testing determined a homozygous 4G/4G polymorphism of the PAI-1 gene. Antiplatelet therapy was started after diagnosis and continued for 8 days with antibiotic therapy. Stroke in children and infants is an infrequent condition associated with substantial morbidity and mortality that needs clinicians' care. This case highlights the significance of awareness about stroke in children and emphasizes on further research to compile evidence-based guidelines for acute stroke therapy in children.
Eye of the Tiger: Looking Beyond Neurodegeneration with Brain Iron Accumulation Disorders
Authors: Ranganath Prajnya , Patil Mallikarjun
Published: February 2021

The “eye-of-the-tiger” sign in brain magnetic resonance imaging (MRI) is typically associated with neurodegeneration with brain iron accumulation disorders, especially pantothenate kinase-associated neurodegeneration. However, very similar neuroimaging findings may be seen in other neurodegenerative disorders involving the basal ganglia. We report here a patient with fucosidosis who had MRI brain findings closely resembling the “eye-of-the-tiger” sign.
Selecting XFEL single-particle snapshots by geometric machine learning
Authors: Cruz-Chú Eduardo R. , Hosseinizadeh Ahmad , Mashayekhi Ghoncheh , Fung Russell , Ourmazd Abbas , Schwander Peter
Published: February 2021

A promising new route for structural biology is single-particle imaging with an X-ray Free-Electron Laser (XFEL). This method has the advantage that the samples do not require crystallization and can be examined at room temperature. However, high-resolution structures can only be obtained from a sufficiently large number of diffraction patterns of individual molecules, so-called single particles. Here, we present a method that allows for efficient identification of single particles in very large XFEL datasets, operates at low signal levels, and is tolerant to background. This method uses supervised Geometric Machine Learning (GML) to extract low-dimensional feature vectors from a training dataset, fuse test datasets into the feature space of training datasets, and separate the data into binary distributions of “single particles” and “non-single particles.” As a proof of principle, we tested simulated and experimental datasets of the Coliphage PR772 virus. We created a training dataset and classified three types of test datasets: First, a noise-free simulated test dataset, which gave near perfect separation. Second, simulated test datasets that were modified to reflect different levels of photon counts and background noise. These modified datasets were used to quantify the predictive limits of our approach. Third, an experimental dataset collected at the Stanford Linear Accelerator Center. The single-particle identification for this experimental dataset was compared with previously published results and it was found that GML covers a wide photon-count range, outperforming other single-particle identification methods. Moreover, a major advantage of GML is its ability to retrieve single particles in the presence of structural variability.
Moving toward mass-conserving simulations of plasma turbulence and kinetic neutrals in the tokamak boundary with the GBS code
Authors: Coroado A. , Ricci P.
Published: February 2021

A model for the simulation of the tokamak boundary is described, which is mass-conserving to leading order in ρs/R0 (where ρs is the ion sound Larmor radius and R0 is the tokamak major radius at the magnetic axis). The model integrates a three-dimensional plasma turbulence model, based on the two-fluid drift-reduced Braginskii equations, a neutral model, based on the discretization of the Boltzmann equation integrated along the neutral path, and proper boundary conditions at the vessel walls. The implementation of the model in the GBS code [Ricci et al., Plasma Phys. Control. Fusion 54, 124047 (2012)] is described and a technical proof of mass conservation is obtained. The simulation results highlight the impact of mass conservation on the plasma and neutral profiles, and the formation of the plasma density profile is explained in terms of plasma and neutral particle fluxes.
Time-dependent behavior of nitric oxide excited states under the effect of electron impact
Authors: Ferdi Mohammed amin , Bouziane Abdelaaziz , Djebli Mourad
Published: February 2021

At high-latitude E and F Earth's ionosphere regions and in the presence of energetic electrons, the impact of electron excitation on nitric oxide (NO) is investigated numerically. Considering an NO cross section implemented in a Boltzmann equation solver, important changes on NO* densities between nighttime and daytime are found. In addition, excited states of NO* exhibit density peaks that have a varying altitude which depends on ionospheric conditions. It is also found that the density is enhanced by solar activity and electron mean energy.