bluuebunny/crossref_metadata_2025 huggingface dataset:
Activation of defective nickel molybdate nanowires for enhanced alkaline electrochemical hydrogen evolution
Authors: An Li , Zhang Yu , Wang Rui , Liu Hanwen , Gao Daqiang , Zhao Yong-Qing , Cheng Fangyi , Xi Pinxian
Published: August 2018

A series of N doped porous metallic NiMoO4 nanowires with concomitant oxygen vacancy defects (N-Vo-NiMoO4 NWs) were prepared as a catalyst for HER in alkaline media. Volcano-like fashion was exhibited for N-Vo-NiMoO4 NWs on various amount of doped-N, with N3-Vo-NiMoO4 NWs being the best one.
Functionalization of diazotetronic acid and application in a stereoselective modular synthesis of pulvinone, aspulvinones A–E, G, Q and their analogues
Authors: Manchoju Amarender , Annadate Ritesh A. , Desquien Lise , Pansare Sunil V.
Published: August 2018

Diastereoselective aldol condensation of diazotetronic acid and a subsequent arene C–H insertion provides an efficient route to the aspulvinone motif.
Boosting the electrochemical performance of carbon cloth negative electrodes by constructing hierarchically porous nitrogen-doped carbon nanofiber layers for all-solid-state asymmetric supercapacitors
Authors: Liu Ya-Nan , Zhang Jia-Nan , Wang Hai-Tao , Kang Xiao-Hui , Bian Shao-Wei
Published: August 2018

Rationally functionalizing a carbon cloth fiber surface with 3D porous nitrogen-doped carbon nanofiber layers can significantly enhance the electrochemical performance of carbon cloth electrode materials.
Water-soluble naphthalene diimides: synthesis, optical properties, and colorimetric detection of biogenic amines
Authors: Weißenstein Annike , Grande Vincenzo , Saha-Möller Chantu R. , Würthner Frank
Published: August 2018

Biocompatible water-soluble naphthalene diimides (NDIs) were synthesized and a core-dichlorinated NDI was shown to detect primary amines and biogenic diamines.
Photophysical behaviour of BODIPY-phenylacetylene macrocyclic dyads for light-harvesting applications
Authors: Yousaf Muhammad , Zarate Ximena , Schott Eduardo , Lough Alan J. , Koivisto Bryan D.
Published: August 2018

The synthesis and study of a family of BODIPY-phenylacetylene macrocycles where donor groups have been added to the macrocycle in order to tune the physicochemical properties and absorption profile is reported.
Incorporation of simvastatin in PLLA membranes for guided bone regeneration: effect of thermal treatment on simvastatin release
Authors: Castro Antonio G. B. , Löwik Dennis W. P. M. , van Steenbergen Mies J. , Jansen John A. , van den Beucken Jeroen J. J. P. , Yang Fang
Published: August 2018

Thermal treatment resulted in a sustained release of simvastatin and a positive response from rBMSCs.
Synthesis and characterization of 4-arm star-shaped amphiphilic block copolymers consisting of poly(ethylene oxide) and poly(ε-caprolactone)
Authors: Bhayo Adnan Murad , Abdul-Karim Rubina , Musharraf Syed Ghulam , Malik Muhammad Imran
Published: August 2018

LCCC on RP columns proves to be efficient for separation of precursors from targeted star block copolymers in a single run.
Two‐degree‐of‐freedom optimal consensus scheme of fractional‐order multi‐agent systems
Authors: Yu Xinyi , Yang Fan , Ou Linlin , Xu Qing , Zhang Weidong
Published: August 2018

A two‐degree‐of‐freedom consensus scheme is investigated for fractional‐order multi‐agent systems with time delay. The two‐degree‐of‐freedom protocol including the individual controllers and the coupling controllers can realise the global tasks and improve consensus performance. Based on such a protocol, a closed‐loop multi‐input multi‐output framework in frequency domain is established. Then the multi‐agent system is decoupled into several subsystems with respect to the eigenvalues of the Laplacian matrix. For each subsystem, the robust stabilising region of the individual controller satisfying index is obtained on the basis of the improved D‐partition method. The controller parameters chosen in the region can provide robustness for the individual agent. The parameters of the coupling controller that ensure fast consensus are determined by first deriving the stabilising region and then searching for the fastest consensus speed in the obtained region. The two‐degree‐of‐freedom structure can trade off the consensus performance and disturbance rejection and is applicable to arbitrary‐order multi‐agent systems with time delay including the fractional‐order system and the integer‐order system. The two‐degree‐of‐freedom consensus controller satisfying other performance criteria can also be designed based on the resultant stabilising region. The simulation results verify the effectiveness of the proposed method.
Long term profit maximization strategy for charging scheduling of electric vehicle charging station
Authors: Rabiee Abdorreza , Ghiasian Ali , Chermahini Moslem Amiri
Published: August 2018

As electric vehicles (EVs) penetration level is increasing, charging infrastructure should expand. This study concentrates on the economic aspects of EV charging stations (EVCSs). When CS capacity is not enough to simultaneously charge all EVs, the EVs will wait in queues to get service. This study presents a model for EVCS and a profit‐based algorithm for charging scheduling (ChSc) of EVs from viewpoint of EVCS owner. The objective function is to maximise long‐term profit of EVCS owner and to minimise delay time of EVs. The charging prices of queues are different from each other, which are determined by the EVCS owner, considering energy price. The time needed to charge an EV from the minimum state of charge to fully charge is considered as a time interval. It is shown that maximising profit at each interval, named as short‐term profit maximisation (STPM), does not necessarily maximise long‐term profit of the EVCS owner. Then, another ChSc strategy, referred to as long‐term profit maximisation (LTPM), is proposed. Simulation results confirm that with LTPM, the owner of EVCS obtains more profit in long term. Also, in comparison to STPM, the incurred average delays of EVs in queues are much less.
PLT‐based spectral features for texture image retrieval
Authors: Sana Joydeb Kumar , Islam Md. Monirul
Published: August 2018

Effective texture feature is an essential component in any content‐based image retrieval system. In this study, new texture features based on image enhancement technique are presented. The authors have effectively exploited power‐law transform (PLT) to extract new spectral texture features called PLT‐based spectral features. Extensive experiments on the Brodatz texture database and Salzburg Textures image database prove the effectiveness of the proposed techniques and show that the proposed features significantly outperform the widely used Gabor and curvelet features. The proposed features are also compared with recently published Gaussian copula models of Gabor feature and local tetra patterns (LTrP). The experimental results confirm that the proposed features have more tolerance to scale, orientation and illumination distortion than the state‐of‐the‐art Gabor, curvelet, Gaussian copula models of Gabor and LTrPs.
Expeditious frequency control of solar photovoltaic/biogas/biodiesel generator based isolated renewable microgrid using grasshopper optimisation algorithm
Authors: Barik Amar Kumar , Das Dulal Chandra
Published: August 2018

This work endeavours to propose an approximate mathematical model of a community based renewablemicrogrid with solar photovoltaic, biogas and biodiesel generators includingbattery storage for load frequency studies. It becomes a great challenge tocoordinate between generation and load demand of the microgrid as the renewablesources are highly unpredictable and nature dependent. To overcome this issue,the responses of the system are studied under different real‐world scenarios ofrenewable source availabilities and load variations with a maiden approachtowards optimising the controller gains using a recent grasshopper optimisationalgorithm (GOA) for efficient frequency control. The frequency responses ofproposed microgrid are compared with different conventional controllers and somepopular optimisation algorithms using MATLAB/Simulink. Finally,proportional–integral–derivative controller with GOA is preferred for the casestudies under four cases of source variations with step load perturbation andone case of simultaneous source and load variations. The results of all thesefive scenarios are found satisfactory in terms of frequency responses andreported in the work.
Co‐allocation of solar field and thermal energy storage for CSP plants in wind‐integrated power system
Authors: Wang Yongcan , Lou Suhua , Wu Yaowu , Wang Shaorong
Published: August 2018

Concentrating solar power (CSP) plants produce electricity without any pollutant emission, which is one of the most attractive alternatives to fossil fuels. The thermal energy storage (TES) benefits CSP plants to produce electricity during temporary weather transients and peak‐load demand hours. However, the main drawback of the CSP plants is the high investment costs. To improve the economic viability, it is necessary to design CSP plants appropriately. In this study, an optimal co‐allocation model of solar field and TES for CSP plants considering with the operation demand of power system is developed to deal with the tradeoff between investment costs and benefits. To consider realistic operating constraints account for the interaction between hourly variability, the uncertainties of solar irradiation and wind power are characterised by a set of scenarios. In addition, the large number of scenarios is reduced to relieve the computational burden. The validity of the proposed model is demonstrated by case study results.
Green synthesis, characterisation, and photocatalytic activity of manganese dioxide nanoparticles
Authors: Hoseinpour Vahid , Souri Mahsa , Ghaemi Nasser
Published: August 2018

In this work, a simple, efficient and eco‐friendly procedure for the green synthesis of manganese dioxide nanoparticles (MnO2 NPs) by Yucca gloriosa leaf extract is described. The MnO2 NPs were synthesised using Y. gloriosa leaf extract and curcumin as reducing and stabilising agents, respectively. Fourier‐transform infrared spectra revealed the involvement of the plant extract in the formation of MnO2 NPs. The ultraviolet–visible absorption spectra of the synthesised MnO2 NPs exhibited absorption peaks at 410 nm, which were attributed to the band gap of the MnO2 NPs. Crystal phase identification of the MnO2 NPs was characterised by X‐ray diffraction analysis and the formation of crystalline MnO2 NPs has been confirmed. Also, the X‐ray diffraction pattern displayed that the average size of MnO2 NPs was about 80 nm. Furthermore, field emission scanning electron microscopy analysis showed that the synthesised MnO2 NPs have a spherical shape. MnO2 NPs have photocatalytic activities for the dye degradation in the visible light region. The photocatalytic activities for the dye degradation of MnO2 NPs were evaluated using Acid Orange as an organic contaminant.
Various damage mechanisms in carbon and silicon materials under femtosecond X-ray irradiation
Authors: Medvedev Nikita , Tkachenko Viktor , Lipp Vladimir , Li Zheng , Ziaja Beata
Published: August 2018

We review the results of our research on damage mechanisms in materials irradiated with femtosecond free-electron-laser (FEL) pulses. They were obtained using our hybrid approach, X-ray-induced thermal and non-thermal transitions (XTANT). Various damage mechanisms are discussed with respect to the pulse fluence and material properties on examples of diamond, amorphous carbon, C60 crystal, and silicon. We indicate the following conditions: those producing thermal melting of targets as a result of electron-ion energy exchange; non-thermal phase transitions due to modification of the interatomic potential; Coulomb explosion due to accumulated net charge in finite-size systems; spallation or ablation at higher fluences due to detachment of sample fragments; and warm dense matter formation. Transient optical coefficients are compared with experimental data whenever available, proving the validity of our modeling approach. Predicted diffraction patterns can be compared with the results of ongoing or future FEL experiments. Limitations of our model and possible future directions of development are outlined.
Analysis and application of whispering gallery modes of the triple-layer-coated microsphere resonator
Authors: Wang Mengyu , Jin Xueying , Li Fei , Wang Keyi
Published: August 2018

Microsphere resonators supporting whispering gallery modes (WGMs) have been extensively applied for considerable fields including narrow linewidth filters, high-sensitivity sensors, and nonlinear optics. We numerically demonstrate a coated microsphere resonator with three layers of high, low, high refractive-index (RI) from inside to outside. A phase matched waveguide is used to overlap the WGMs evanescent radiation field. Eigen-mode, relative intensity spectra, electromagnetic (EM) field distributions are observed to analyze resonant characteristics of WGMs by using the finite difference time domain method. As a result, two brilliant rings with strong EM fields distribute in two high-RI layers. By optimizing the gap distance between the microsphere and waveguide, the WGMs of two high-RI layer are efficiently excited. More energy is stored in such a structure rather than a single-layer-coated microsphere. Our approach provides the RI sensing application with such a triple-layer-coated structure.
Mixed convection over a horizontal circular cylinder embedded in porous medium immersed in a nanofluid with convective boundary conditions at lower stagnation point: A numerical solution
Authors: Norhafizah Md Sarif , Mohd Zuki Sallhe , Nazar Roslinda
Published: August 2018

This study aims to examine the effect of governing parameters on the flow and heat transfer of the steady mixed convection flow embedded in porous medium with convective boundary conditions. The resulting system of nonlinear partial differential equations is solved numerically. The special case at the lower stagnation point of the cylinder is observed and the case where bottom surface of the cylinder is heated by convection from hot fluids is considered. Numerical solutions are obtained for the velocity, temperature and nanoparticle volume fraction profiles for two values of governing parameters namely convective parameter γ and Lewis number Le. It is found that as the convective parameter γ increases, velocity profile, temperature and nanoparticle volume fraction profile also increases.
A kind of entity recognition algorithm based on Hadoop for power big data
Authors: Qi Jun , Ge Weichun , Li Zhao , Li Wei , Zhang Hongyu , Zhao Jinghong , Jin Chengming , Yu Liangliang , Chen Shuo , Liu Biqi , Yang Mingyu
Published: August 2018

With the coming of the era of big data, traditional entity recognition technologies have been unable to effectively finish data preprocessing due to large scale of power grid data and complex volume type features. The rising of Hadoop technologies in these years can deal with big data processings better. Therefore, this paper proposes a power big data entity recognition algorithm based on Hadoop. It applies the discretization algorithm to select higher information accuracy discrete points and put forward a discretization evaluation indicator. In the end, we finish entity recognition of the monitoring data of wind turbines on Hadoop platform.Experimental results show that the proposed algorithm performs well in terms of correctness and breakpoint number experiments and it has a good speed-up ratio. The proposed algorithm can apply to power large data entity recognition processing.
Research of specific field ultra-short text classification based on collaborative filtering
algorithm
Authors: Yang Weichen , Si Yanwei
Published: August 2018

In some specific fields, there are a lot of ultra-short texts that need to be categorized. This paper proposes an ultra-short text classification method based on collaborative filtering algorithm aiming at the problems such as short text content, short length, sparse features, and large number of categories in certain fields. First, converting ultra-short text into word frequency vector by doing Chinese word segmentation and calculating word frequency; Secondly, combining relevant data in specific fields, defining the ultra-short texts as users, categories as items, and then constructing a user-item recommendation matrix. Finally, calculating text similarity by using cosine similarity method and obtaining the classification results. The experimental results show that the proposed method can well solve the problem of classification of ultra-short texts in specific fields, and the average accuracy is 9.19% and 3.81% higher than vector space model and topic similarity method respectively.
A novel indoor localization scheme based on refined fingerprint-based autoencoder network
Authors: Mei Junhui , Xi Juntong
Published: August 2018

Indoor positioning systems have attracted increasing interests for the emergency of location based service in indoor environments. Wi-Fi fingerprint-based localization scheme has become a promising indoor localization technique due to the availability of access point (AP) and its low cost. However, the received signal strength (RSS) values are easily fluctuated by the interference of multi-path effects, which introduce propagation errors into localization results. In order to address the issue, a fingerprint-based autoencoder network scheme is proposed to learn the essential features from the measured coarse RSS values and extract the trained weight parameters of autoencoder network as refined fingerprints. The extracted fingerprints are able to represent the environmental properties and display strong robustness with fluctuated signals. The proposed scheme is further implemented in complex indoor scenes, which substantiate the effectiveness and accuracy improvement compared with other RSS-based schemes.
Efficient zero-copy mechanism for intelligent video surveillance networks
Authors: Chen Shiyan , Li Dagang
Published: August 2018

Most of today’s intelligent video surveillance systems are based on Linux core and rely on the kernel’s socket mechanism for data transportation. In this paper, we propose APRO, a novel framework with optimized zero-copy capability customized for video surveillance networks. Without the help of special hardware support such as RNIC or NetFPGA, the software-based APRO can effectively reduce the CPU overhead and decrease the transmission latency, both of which are much appreciated for resource-limited video surveillance networks. Furthermore, unlike other software-based zero-copy mechanisms, in APRO zero-copied data from network packets are already reassembled and page aligned for user-spac applications to utilize, which makes it a ‘true’ zero-copy solution for localhost applications. The proposed mechanism is compared with standard TCP and netmap, a typical zero-copy framework. Simulation results show that APRO outperforms both TCP and localhost optimized netmap implementation with the smallest transmission delay and lowest CPU consumption.
An algorithm for detecting abnormal electricity mode of power users
Authors: Wang Diangang , Song Shuo , Gan Wei , Huang Kun
Published: August 2018

In order to reduce the non-technical loss and reduce the operating cost of the power company, an abnormal power consumption detection algorithm is proposed. The algorithm includes feature extraction, principal component analysis, grid processing, local outliers, and so on. Firstly, we extract several feature quantities that characterize the user's power consumption pattern, and map the X users to the two-dimensional plane by principal component analysis. Data visualization and easy to calculate local outliers, and grid processing techniques to filter out data points in low density regions. The algorithm is used to reduce the number of training samples in the power user data set, and to output the anomalies and probabilities of all users' behavior. The experimental results show that the use of the sorting only need to detect the anomaly of a few users can find a large number of abnormal users, significantly improve the efficiency of the algorithm.
Research on data transmission application based on USB3.0 bridge chip and FPGA
Authors: Ma Dezhuang , Deng Lunhui
Published: August 2018

Aiming at the shortcomings of data transmission system, such as poor portability, unstable data transmission and high cost, the combination of FPGA and USB3.0 technology is adopted to realize the real-time and reliable access to the host computer platform. Practical application shows that this platform has the advantages of small size, low power consumption, hot plug, etc. And the system meets the design requirements.
Target function location based on code coverage analysis
Authors: Jin Kaiwen , Li Qingbao , Chen Zhifeng
Published: August 2018

How to locate the target function faster and more accurately is a key problem of Automatic Reverse-Engineering of Software Programs. In order to solve this problem, a target function location method based on code coverage analysis is proposed. Firstly, it obtains function call information of the program and calculate the suspicious rate of each function. And then a stability factor is proposed to reduce the noise functions. Finally, the target function is successfully located. The experimental results show the method proposed has linear time complexity. For software programs with million function calls, it can accurately locate the target function within several minutes, the performance and accuracy are greately improved compared to the contrast methods.
Multi-targets localization based on ARMA and GA in WSNs
Authors: Zhang Heng , Pan Zhongming
Published: August 2018

Multi-target localization methods for locating of the movingtarget in interested area monitored by Wireless Sensor Networks (WSNs) are nowadays a popular subject of study. The methods can be classified into two categories: range-free algorithm and range-based algorithm. In this work, we propose a novel multi-target localization method, which belongs to the category of range-based algorithm, by using a genetic algorithm (GA) for searching optimal solution of the objective function of multi-target localization. The objective function is only a group of linear equations with independent variables of acoustic energies calculated at each sensor-node in a WSN. However, application of the method, the accuracy of multi-target localization is sensitive to the SNR of the measured sound signals at each node, thus a denoising strategy should be inserted into the method. It turned out that the measured sound noise, comparing intrinsic sensor noise and environmental noise, may be considered as an Autoregressive Moving Average (ARMA) process. Thus, by building the ARMA model, the noise sequence commingled with the target signals can be predicted. As a consequence, the power of the noises can be subtracted from the measured sound signals for revealing the target signal's power. The results in present work demonstrate the advantage of the proposed method.
A fundamental study of parameter adjustable additive manufacturing process based on FDM process
Authors: Wan Qia , Xu Youjian , Lu Can
Published: August 2018

In Fused deposition modeling (FDM) process, there has been a confliction between high productivity and high quality of products. The product resolution is proportional to the flow rate of heated material extrusion, which directly affects the build time. To reduce the build time with acceptable resolution, the idea of parameter adjustable printing process has been introduced. The controllable extruder was modified and two types of diameter changeable nozzle have been designed. This work realizes different resolution building based on the part geometry during FDM process, which can efficiently assure the quality of products and improve the productivity at the same time.
Study on column generation for the lot-sizing and scheduling problem with sequencedependent setup time
Authors: Zhang Dandan , Zhang Canrong
Published: August 2018

The capacitated lot-sizing and scheduling problem with sequence-dependent setup time and carryover setup state is a challenge problem in the semiconductor assembly and test manufacturing. For the problem, a new mixed integer programming model is proposed, followed by exploring its relative efficiency in obtaining optimal solutions and linearly relaxed optimal solutions. On account of the sequence-dependent setup time and the carryover of setup states, a per-machine Danzig Wolfe decomposition is proposed. We then build a statistical estimation model to describe correlation between the optimal solutions and two lower bounds including the linear relaxation solutions, and the pricing sub-problem solutions of Danzig Wolfe decomposition, which gives insight on the optimal values about information regarding whether or not the setup variables in the optimal solution take the value of 1, and the information is further used in the branch and select procedure. Numerical experiments are conducted to test the performance of the algorithm.
Information collection for fraud detection in P2P financial market
Authors: Wang Hao , Wang Zonghu , Zhang Bin , Zhou Jun
Published: August 2018

Fintech companies have been facing challenges from fraudulent behavior for a long time. Fraud rate in Chinese P2P financial market could go as high as 10%. It is crucial to collect sufficient information of the user as input to the anti-fraud process. Data collection framework for Fintech companies are different from conventional internet firms. With individual-based crawling request, we need to deal with new challenges negligible elsewhere. In this paper, we give an outline of how we collect data from the web to facilitate our anti-fraud process. We also overview the challenges and solutions to our problems. Our team at HC Financial Service Group is one of the few companies that are capable of developing full-fledged crawlers on our own.
The research of the pulse oxygen supply based on the fuzzy control technology
Authors: Hu Faling , Niu Tongfeng , Yao Jun , Cui Bingyan , Xu Haoxing , Liu Hong , Chen Shujuan , Zhou Yusong
Published: August 2018

According to the working principle of pulse oxygen supplies, we analyze how to realize the control of the oxygen flow by double different valves. a two-dimensional fuzzy control system is proposed to solve the unstable problem, which is brought by the shortcomings of the open-loop control system. We add a new parameter, the rate of the differential pressure signal changes, which contributes to a close –loop control system and increases the stability of the system. The experiments and the data show that the fuzzy control system make the process of breathing much more comfortable and solve the hysteresis and overshoot caused by the open-loop control system. The product reliability has been greatly improved.
Smart disaster prediction application using flood risk analytics towards sustainable climate action
Authors: Orozco Michael M. , Caballero Jonathan M.
Published: August 2018

Disaster prediction devices for early warning system are used by many countries for disaster awareness. This study developed smart disaster prediction application using microcontrollers and sensors to analyze the river water level for flood using flood risk analytics. Specifically, it monitors the river water level, water pressure and rain fallusing microcontroller, applying statistical modeling algorithms for river flood prediction, and monitor flood in a web-based system with SMS notification and alarm to the community as an early warning. The researchers used the system development method to measure the prototype feasibility study. The researchers applied the statistical modeling algorithm as the data can be observed from time to time or on a daily basis for the predictive analytics. Based on the 7-days observation result, rainfall resulted in precipitation average of 10.96 mm, water pressure with an average of 40.92 pound per square inch (psi) and water level averaged 138.78 cm. The tropical depression during the 7 days’observation reflected the average data result from the sensors as the target of the study. The result of the prototype device used the City Disaster Risk and Reduction management office (CDRRMO) as history logs for a flood risk and it was proven accurate which makes a good use for disaster prediction.
Guided lazy snapping for long thin object selection
Authors: Tran Nam H. , Seo Dongsun , Tu Henry T.H.
Published: August 2018

We show a novel way to select long thin objects in an image by enhancing the output of the existing foreground/background image segmentation methods. Most superpixel-based methods fail to select the long thin details, such as legs and whiskers, and extended curves from the main objects. We observe, however, the output without long thin details, can be used as the guided information to obtain the connected components. Based on this observation, our Guided Lazy Snapping method overcomes the limitation of the Lazy Snapping methods (or other alternatives superpixel-based segmentation method) to select long thin objects. The results show that connected components in the image can be selected without having a lot of user interactions (mouse clicks) on each extended parts of the object.
A method of identifying and analyzing Outgoing Long-wave Radiation anomalies before earthquake
Authors: Jiang Xiaoying , Kong Xiangzeng , Guo Gongde
Published: August 2018

A large amount of anomalous information will appear before the earthquake, but it is difficult to identify and analyze valuable anomalous information from large-scale data. To solve this problem, this paper presents a method of pre-earthquake Outgoing Long-wave Radiation (OLR) anomaly identification and analysis based on quantum walking algorithm. The National Oceanic and Atmospheric Administration (NOAA) data are used to process and analyze the OLR data before and after the 6 major earthquakes in 2017 in western China.The results show that different degrees of thermal infrared anomalies have appeared before and after these large earthquakes. In this paper, we also analyze and discuss the similarities and differences of these changes by combining geological conditions and other factors.
Sensitivity investigation of the microfiber-toslab evanescent wave sensors
Authors: Li Xianli
Published: August 2018

Microfiber-to-slab sensor is comprised of a tapered fiber in evanescent contact with a multimode slab waveguide. The effects of the sensor configuration parameters on its evanescent wave sensitivity were investigated through theoretical analysis. On the basis of that, the rules for fabricating a microfiber-to-slab sensor with high device sensitivity were presented. By optimizing geometry parameters, it was shown that the resonant wavelength sensitivity can be as high as nearly 20000 nm/RIU. The conclusions derived from our work may be used for design and optimization of microfiber-to-slab devices for practical applications.
Fibromyalgiesyndrom – Bedeutung für die Rehabilitation
Authors: Köllner Volker , Rupp Stefan
Published: August 2018

Das Fibromyalgiesyndrom (FMS) ist eines der häufigsten chronischen Schmerzsyndrome. 2013 waren 2,1% der deutschen Bevölkerung betroffen, wobei die Diagnose nur anhand subjektiver Beschwerdeangaben gestellt werden kann. Dieser Beitrag soll konkrete Hinweise zu Krankheitskonzept, Diagnostik, Therapie, Rehabilitation und sozialmedizinischer Beurteilung beim FMS geben. Grundlage ist die 2. Aktualisierung (2017) der S3-Leitlinie zum FMS.
Frakturen der Halswirbelsäule bei ankylosierender Spondylitis und diffuser idiopathischer skeletaler Hyperostose
Authors: Vordemvenne Thomas
Published: August 2018

Frakturen der Halswirbelsäule bei ankylosierender Spondyilitis oder DISH stellen eine Herausforderung für das perioperative Management dar. Es handelt sich beinahe ausnahmslos um biomechanisch instabile Läsionen des AO-Typs B und C, die gerade infolge von Bagatelltraumen entstehen können. Neurologische Symptome wie auch Verletzungen der hirnversorgenden Gefäße sind häufig. Eine konsequente Schichtbilddiagnostik der gesamten Wirbelsäule gehört zum Goldstandard, um synchrone Verletzungen nicht zu übersehen. Das Patientengut ist per se von einer erhöhten Morbidität und Mortalität gekennzeichnet. So liegt das Prinzip in der konsequenten operativen Stabilisierung, Dekompression und Schaffung einer frühen Rehabilitationsfähigkeit des Patienten. Dies kann durch eine primär dorsale Instrumentierung möglich werden. Eine anteriore Gegenstabilisierung ist im Falle eines ventralen Defektzustandes in Einzelfällen nötig. Bei der DISH ist bei anterioren Fusionsoperationen auf die konsequente Reduktion der ossären Spangen zu achten, um postoperative Dysphagien zu verhindern.
Laser-generated Rayleigh wave for width gauging of subsurface lateral rectangular defects
Authors: Wang Chuanyong , Sun Anyu , Yang Xiaoyu , Ju Bing-Feng , Pan Yongdong
Published: August 2018

In this study, the widths of subsurface lateral rectangular defects were successfully gauged using laser-generated Rayleigh waves. Finite element analysis was used to simulate the interaction between Rayleigh waves and subsurface defects. The results of the simulation show that diffracted bulk modes resulting from the interaction between Rayleigh waves and subsurface defects may interact with the free surface. Modes are converted into Rayleigh waves that propagate along the surface. The arrival time of reflected mode-converted Rayleigh waves remains constant, even when the height of subsurface defects increases. However, as the depth increases, the arrival time of reflected mode-converted Rayleigh waves changes due to mode conversion caused by diffracted bulk modes interacting with the free surface. The influence of mode conversion was quantitatively analyzed and taken into account in the width measurement method for subsurface lateral defects. Experimental results are consistent with simulation results and show that Rayleigh waves induced by a pulsed line laser are sensitive to subsurface defects. Finally, the proposed method may be potentially useful for width measurements of other types of subsurface structures.
Implementation and application of the peak scaling method for temperature measurement in the laser heated diamond anvil cell
Authors: Kunz Martin , Yan Jinyuan , Cornell Earl , Domning Edward E. , Yen C. Ethan , Doran Andrew , Beavers Christine M. , Treger Aaron , Williams Quentin , MacDowell Alastair A.
Published: August 2018

A new design for a double-sided high-pressure diamond anvil cell laser heating set-up is described. The prototype is deployed at beamline 12.2.2 of the Advanced Light Source at Lawrence Berkeley National Lab. Our compact design features shortened mechanical lever arms, which results in more stable imaging optics, and thus more user friendly and more reliable temperature measurements based on pyrometry. A modification of the peak scaling method was implemented for pyrometry, including an iterative method to determine the absolute peak temperature, thus allowing for quasi-real time temperature mapping of the actual hotspot within a laser-heated diamond anvil cell without any assumptions on shape, size, and symmetry of the hotspot and without any assumptions to the relationship between fitted temperature and peak temperature. This is important since we show that the relationship between peak temperature and temperature obtained by fitting the Planck function against the thermal emission spectrum averaged over the entire hotspot is not constant but depends on variable fitting parameters (in particular, the size and position of the fitting window). The accuracy of the method is confirmed through measuring melting points of metal wires at ambient pressure. Having absolute temperature maps in real time allows for more differentiated analyses of laser heating experiments. We present such an example of the pressure variations within a heated hotspot of AgI at a loaded base pressure of 3.8 GPa.
Intensity distortions due to phase-only spatial light modulation: Characterization for applications in electronic speckle-pattern interferometry
Authors: Bilgeri L. M. , Salazar Bloise F. , Lu M. , Wang S. , Jakobi M. , Koch A. W.
Published: August 2018

Electronic speckle-pattern interferometry (ESPI) is a powerful tool for precise, full-field, and non-contact contouring of optically rough surfaces. Due to the interferometric principle, the sensitivity of ESPI is directly related to the involved wavelengths and is thereby a global parameter. Surfaces with a broad variation of phase gradients, as, for instance, a target with both smooth and comparatively steep areas, result in just partially resolvable fringe interferograms. In recent studies, spatial light modulators (SLMs) have been implemented to adapt the interferometric reference phase front to the measurement task and broaden or squeeze the fringe spacing locally in critical areas. This method is limited by diffraction effects, observable for all types of phase-only SLMs. We demonstrate a straight-forward model, describing the diffraction-based intensity distortions occurring in interferograms after wavefront adaptation. The aim is to characterize the intensity distortions by means of the proposed model and minimize their impact, especially with regard to phase-only spatial light modulation in ESPI. For validation, the modeled behavior of SLMs is compared to the experimental results, obtained for two different SLM designs. Finally, experiments are presented, which demonstrate a successful adaptation of the interferometric reference phase front in compliance with the boundary conditions determined by the model.
Benchmarking of GGA density functionals for modeling structures of nanoporous, rigid and flexible MOFs
Authors: Formalik Filip , Fischer Michael , Rogacka Justyna , Firlej Lucyna , Kuchta Bogdan
Published: August 2018

The adequate choice of the interaction model is essential to reproduce qualitatively and estimate quantitatively the experimentally observed characteristics of materials or phenomena in computer simulations. Here we present the results of a benchmarking of density-functional theory calculations of rigid and flexible metal-organic frameworks (MOFs). The stability of these systems depends on the dispersion interactions. We compare the performance of two functionals, Perdew-Burke-Ernzerhof (PBE) and PBE designed for solids, with and without the dispersion corrections (D2 and TS), in reproducing the high-accuracy low-temperature X-ray and neutron diffraction data for both groups of MOFs. We focus our analysis on the key structural parameters: the lattice parameters, bond lengths, and angles. We show that the dispersion long range correction is essential to stabilize the structures and, in some cases, to converge the system to a geometry that is in line with the experimentally observed structure, especially for breathing MIL-53 structures or zeolitic imidazolate frameworks. We find that for all structures and all analyzed parameters, the D2-corrected PBE functional performs the best, except for bonds involving the metal ions; however, even for these bonds the difference between the experimentally observed and calculated lengths is small. Therefore, we recommend the use of the PBE-D2 functional in further numerical analyses of rigid and flexible nanoporous MOFs.
Adaptive locally resonant metamaterials leveraging shape memory alloys
Authors: Candido de Sousa Vagner , Sugino Christopher , De Marqui Junior Carlos , Erturk Alper
Published: August 2018

Locally resonant metamaterials leveraging shape memory alloy (SMA) springs are explored in this work in an effort to develop adaptive metamaterial configurations that can exhibit tunable bandgap properties as well as enhanced damping capabilities. An analytical model for a locally resonant metamaterial beam in transverse vibrations is combined with an SMA model for the resonator springs to investigate and leverage the potential of temperature-induced phase transformations and stress-induced hysteretic behavior of the springs. Two case studies are presented for this new class of smart metamaterials and the resulting finite metastructures. In one case, SMA resonators operate in the linear elastic regime, first at low temperature (martensitic behavior) and then at high temperature (austenitic behavior), demonstrating how the bandgap can be tuned to a different frequency range by altering the SMA elastic modulus with temperature. In the second case, the SMA springs are kept at high temperature at all times to operate in the nonlinear regime, so that the hysteresis associated with the SMA pseudoelastic effect is manifested, yielding additional dissipation over a range of frequencies, especially for the modes right outside the bandgap.
Identification of Ge vacancies as electronic defects in methyl- and hydrogen-terminated germanane
Authors: Asel Thaddeus J. , Yanchenko Eric , Yang Xiao , Jiang Shishi , Krymowski Kevin , Wang Yaxian , Trout Amanda , McComb David W. , Windl Wolfgang , Goldberger Joshua E. , Brillson Leonard J.
Published: August 2018

We use a combination of optical and electrostatic surface science techniques to measure electronically active native defects in multilayer GeCH3 and GeH, two-dimensional (2D) functionalized materials. Chemical processing techniques coupled with density functional theory enable us to identify the specific physical nature of both native point defects and synthesis-related impurities which can limit the optical and charge transport properties of these materials. Direct comparison of optical measurements with calculated electronic levels provides identification of these localized, deep level gap states and confirms partial H-passivation of dangling bonds, revealing synthesis and processing methods needed to control specific defects and optimize these 2D materials for emergent solid state-electronics.
Metastable vortex-like polarization textures in ferroelectric nanoparticles of different shapes and sizes
Authors: Pitike Krishna Chaitanya , Mangeri John , Whitelock Hope , Patel Tulsi , Dyer Pamela , Alpay S. Pamir , Nakhmanson Serge
Published: August 2018

The dependence of the polarization texture topology in ferroelectric PbTiO3 nanoparticles, embedded in a dielectric matrix, on the particle shape and size was investigated with a time-dependent Landau-Ginzburg-Devonshire approach combined with coupled-physics finite-element-method based simulations. Particle shapes belonging to the superellipsoidal family were probed, including octahedral, cubic, and intermediate geometries. For each shape, a parametric sweep of particle sizes ranging from 2 to 40 nm was conducted, revealing a general trend for the texture transformations from a monodomain, through a vortex-like, to a multidomain state, as the size increases. Critical particle sizes for the texture instabilities were found to be strongly dependent on the particle shape, with octahedral particles undergoing transitions at much larger volumes, compared to the cubic particles. Furthermore, for each of the considered non-spherical shapes of appropriate size, it was possible to obtain multiple vortex-like textures whose paraelectric cores are aligned with every rotational axis of the particle point symmetry group. The shape-dependent metastability of the vortex-like textures opens up new avenues for controlling polarization at the nanoscale in a variety of technological applications.
The ice-like vortex states in a nanostructured superconducting film with a dice lattice of elongated antidots
Authors: He An , Xue Cun , Zhou Y.-H.
Published: August 2018

We study the degeneracy of the superconducting vortex ground state in a dice lattice of elongated antidots within the Ginzburg-Landau (GL) theory. It is found there are two kinds of unit cells in this dice lattice, namely z6 unit cell where six antibars meet and z3 unit cell where three antibars meet. This can result in more complicated vortex arrangements in the unit cells than that in the kagome lattice. We demonstrate that the vortex patterns at specific fractional magnetic fields can be determined by the local constraints, which presented the ice-like vortex configuration based on the degeneracy rules. This is the reason that the vortex system follows the rule of “two vortices in, one vortex out” or “two vortices out, one vortex in” at each vertex of z3 unit cell. The so-called degeneracy rules are explored by considering nearest-neighbor interaction. Thus, it is possible to realize a rich variety of ice-like vortex configurations in a large area of the sample.
Role of electronic thermal transport in amorphous metal recrystallization: A molecular dynamics study
Authors: McClure Zachary D. , Reeve Samuel Temple , Strachan Alejandro
Published: August 2018

Recrystallization of glasses is important in a wide range of applications including electronics and reactive materials. Molecular dynamics (MD) has been used to provide an atomic picture of this process, but prior work has neglected the thermal transport role of electrons, the dominant thermal carrier in metallic systems. We characterize the role of electronic thermal conductivity on the velocity of recrystallization in Ni using MD coupled to a continuum description of electronic thermal transport via a two-temperature model. Our simulations show that for strong enough coupling between electrons and ions, the increased thermal conductivity removes the heat from the exothermic recrystallization process more efficiently, leading to a lower effective temperature at the recrystallization front and, consequently, lower propagation velocity. We characterize how electron-phonon coupling strength and system size affect front propagation velocity. Interestingly, we find that initial recrystallization velocity increases with decreasing system size due to higher overall temperatures. Overall, we show that a more accurate description of thermal transport due to the incorporation of electrons results in better agreement with experiments.
Computational modeling of proton acceleration with multi-picosecond and high energy, kilojoule, lasers
Authors: Kim J. , Kemp A. J. , Wilks S. C. , Kalantar D. H. , Kerr S. , Mariscal D. , Beg F. N. , McGuffey C. , Ma T.
Published: August 2018

We use computational modeling to investigate proton beam generation from kilojoule, multi-picosecond laser pulses pertinent to several recently commissioned, large-scale laser facilities. The dependencies of proton acceleration on electron source parameters including pulse duration, temperature, and flux are independently and systematically evaluated. Proton acceleration is found to depend not only on the source size and peak temperature of the injected electrons but also on the rate of increase for a more physical time-varying temperature. Simulations of a 10 ps, sub-relativistic intensity (8 × 1017 W/cm2) at 1 μm wavelength laser pulse show that energetic electrons generated within the expanding under-dense laser-produced plasma sustain the proton acceleration for ∼20 ps. This results in 15 MeV energy gain of the protons, well above what would be predicted based on conventional intensity scalings or what has been observed with shorter pulses. Using this prolonged acceleration, a scheme consisting of a 1 ps and 10 ps double pulse is shown to further boost proton maximum energy.