bluuebunny/crossref_metadata_2025 huggingface dataset:
Planets around evolved intermediate-mass stars
Authors: Delgado Mena E. , Lovis C. , Santos N. C. , Gomes da Silva J. , Mortier A. , Tsantaki M. , Sousa S. G. , Figueira P. , Cunha M. S. , Campante T. L. , Adibekyan V. , Faria J. P. , Montalto M.
Published: August 2018

Aims.The aim of this work is to search for planets around intermediate-mass stars in open clusters using data from an extensive survey with more than 15 yr of observations.

Methods.We obtain high-precision radial velocities (RV) with the HARPS spectrograph for a sample of 142 giant stars in 17 open clusters. We fit Keplerian orbits when a significant periodic signal is detected. We also study the variation of stellar activity indicators and line-profile variations to discard stellar-induced signals.

Results.We present the discovery of a periodic RV signal compatible with the presence of a planet candidate in the 1.15 Gyr open cluster IC 4651 orbiting the 2.06M⊙star No. 9122. If confirmed, the planet candidate would have a minimum mass of 7.2MJand a period of 747 days. However, we also find that the full width at half maximum (FWHM) of the cross-correlation function (CCF) varies with a period close to the RV, casting doubts on the planetary nature of the signal. We also provide refined parameters for the previously discovered planet around NGC 2423 No. 3, but show evidence that the bisector inverse slope (BIS) of the CCF is correlated with the RV during some of the observing periods. We consider this fact as a warning that this might not be a real planet and that the RV variations could be caused by stellar activity and/or pulsations. Finally, we show that the previously reported signal by a brown dwarf around NGC 4349 No. 127 is presumably produced by stellar activity modulation.

Conclusions.The long-term monitoring of several red giants in open clusters has allowed us to find periodic RV variations in several stars. However, we also show that the follow-up of this kind of stars should last more than one orbital period to detect long-term signals of stellar origin. This work highlights the fact that although it is possible to detect planets around red giants, large-amplitude, long-period RV modulations do exist in such stars that can mimic the presence of an orbiting planetary body. Therefore, we need to better understand how such RV modulations behave as stars evolve along the red giant branch and perform a detailed study of all the possible stellar-induced signals (e.g., spots, pulsations, granulation) to comprehend the origin of RV variations.
Exploring galaxy evolution with generative models
Authors: Schawinski Kevin , Turp M. Dennis , Zhang Ce
Published: August 2018

Context. Generative models open up the possibility to interrogate scientific data in a more data-driven way.

Aims. We propose a method that uses generative models to explore hypotheses in astrophysics and other areas. We use a neural network to show how we can independently manipulate physical attributes by encoding objects in latent space.

Methods. By learning a latent space representation of the data, we can use this network to forward model and explore hypotheses in a data-driven way. We train a neural network to generate artificial data to test hypotheses for the underlying physical processes.

Results. We demonstrate this process using a well-studied process in astrophysics, the quenching of star formation in galaxies as they move from low-to high-density environments. This approach can help explore astrophysical and other phenomena in a way that is different from current methods based on simulations and observations.
The investigation of the coefficients of materials of hard hulls of autonomous deep-underwater vehicles
Authors: Karpachev Aleksandr
Published: August 2018

The conceptional projecting of new type of marine technique presented by autonomous underwater vehicles based on new type of materials for hard hulls. As is known, the quality of the materials of hard hulls depends on the Poisson coefficient and the modulus of elasticity (Young), which play an important role in calculating the critical pressure for stability. The problem of finding the optimum values of these coefficients (the maximum of the critical pressure) is of great interest for the creation of ideal materials for the hard hulls of underwater vehicles. Such a problem must be solved in conjunction with the task of optimizing another coefficient - the material's fluidity module. In the Investigations it is very important to accurately calculate the critical pressure for the stability of the hard hulls of underwater vehicles. This method of exact calculation has been created and tested in practice for known materials: aluminum alloy, steel, titanium and fiberglass. The method was also used to solve the problem of creating a new type of material for hard hulls with optimal values of the yield coefficients, Jung and Poisson.
New metallic mesh designing with high electromagnetic shielding
Authors: Qiu Longjia , Li Li , Pan Zhifeng , Zhu Bin , Sun Xiangbing , Yan Wei
Published: August 2018

Metallic mesh is an important technic approach to realize the stealth of the electro-optical radar. This paper demonstrates the designing thoughts of metallic mesh, and in the conclusion, this paper achieves the integrated design method by analysing electromagnetic shielding, permeability and so on. By using this method, a metallic mesh designing with high electromagnetic shielding is designed, which will make the aircraft gain better stealth effect in combat.
Research on mechanism and process of paint removal with pulsed fiber laser
Authors: Zeng Xiaodi , Qin Wenbin , Li Jing , Wang Zhiyong
Published: August 2018

Compared with the traditional cleaning technology, laser cleaning, as a new type of industrial technology, has the advantages of high cleaning rate, green pollution-free and low cost. So laser cleaning is widely used in the fields of paint removal. This paper analyzes that the mechanism of paint removal and heat transfer process in the paint layer and substrate, also determines the process parameters of affect the laser paint removal. The removal of paint from steel substrate with fiber laser of frequency adjustable 20 to 500kHz at 1064nm is reported, researching impact that laser energy density,scanning speed and line width on the paint removal effect. The results show that, the 100μm paint layer can be removed completely while keeping the substrate undamaged with the laser energy density of 10.19J/cm2 and speed of 4200mm/s and width of 0.02mm. In order to get better results, the cleaning efficiency can be improved by increasing the power, speed and spot size under the right energy density.
Gas turbine power calculation method of turboshaft based on simulation and performance model
Authors: Wu Heng , Zhao Shufan , Zhang Jijun , Sun Bo , Song Hanqiang
Published: August 2018

Gas turbine power of turboshaft engine cannot be measured, a total of five typical steady state point test data from the ground slow state to the maximum state were selected according to the factory acceptance test drive of a certain type of carrier-based helicopter turboshaft engine. Combustion chamber three-dimensional simulation model was established to carry on simulation analysis of different typical steady state combustion process. The simulated combustion chamber exit section parameters are input into the established gas turbine isentropic adiabatic aerodynamic calculation model to obtain the gas turbine power and outlet temperature. Select five typical steady state points of five sets of turboshaft engines on the same type to repeat the above calculation process, and compare the calculated value of gas turbine outlet temperature with the acceptance test values, it is found that the error values are all within 5%, and the effectiveness and accuracy of the gas turbine power calculation method are verified.
Abnormal electricity detection with hybrid deep neural network model
Authors: Liu Jie , Cao Xiang , Wang Diangang , Pan Kejia , Zhang Cheng , Wang Xin
Published: August 2018

This paper tackles a new challenge in abnormal electricity detection: how to promptly detect stealing electricity behavior by a large-scale data from power users. Proposed scheme firstly forms power consumption gradient model by extracting daily trend indicators of electricity consumption, which can exactly reflect the short-term power consumption trend for each user. Furthermore, we design the line-losing model by analyzing the difference between power supplying and actual power consumption. Finally, a hybrid deep neural network detection model is built by combining with the power consumption gradient model and the line-losing model, which can quickly pin down to the abnormal electricity users. Comprehensive experiments are implemented by large-scale user samples from the State Grid Corporation and Tensorflow framework. Extensive results show that comparing with the state-of-the-arts, proposed scheme has a superior detection performance, and therefore is believed to be able to give a better guidance to abnormal electricity detection.
K-anonymity model for privacy-preserving soccer fitness data publishing
Authors: Li Rong , An Shushan , Li Dong , Dong Jian , Bai Wanjian , Li Hongmei , Zhang Zhiming , Lin Qingyang
Published: August 2018

With the development of data mining technology, more and more researchers use the soccer fitness data to analyse the ranking of soccer athletes' and professional training. However, the direct release of soccer fitness data may leak the personal privacy of soccer athletes, so how to ensure the utility of soccer fitness data and the privacy of soccer player has become an issue. In this paper, we point out the linking attack existing in soccer fitness data, which the attackers can use the auxiliary demographic data as background information to attack the published physical data. So the attackers will map the privacy data and the athlete together. At the same time, we apply the partitioning-based and k-means clustering-based two k-anonymity algorithms to the soccer fitness data publishing to trade-offs the data utility and the personal privacy. Experimental results showed that the performance of methods is convincing.
Energy efficiency of cooperative D2D communications underlaying LTE-A networks
Authors: Zhang Xiaoying , Khwaja Ahmed , Naeem Muhammad , Anpalagan Alagan
Published: August 2018

Device-to-device (D2D) communications underlaying LTE-A networks is expected to bring significant benefits for resource utilization and energy efficiency (EE) improvement of user equipment (UE). However, the allocation of radio and power resources to D2D communications needs elaborate coordination, because of the interference between D2D communications and cellular communications. In this paper, we propose an energy-efficient cooperative D2D communication (EECD2D) technique using a power allocation algorithm, aiming at maximizing EE introduced by D2D communications in LET-A networks. Specifically, we define four D2D and cellular combinations based on distances, and analyze average EE of EECD2D and that of cooperative D2D communications without optimization. Results show that average EE of our algorithm is much higher than that without optimization, and closer D2D cooperators and distant cellular UEs whose uplink resource is reused, achieve highest average energy efficiency.
A sign language smart phone based on realistic animation
Authors: Wang Wentong , Zhang Wenhui , Sun Bin
Published: August 2018

Mobile phones are now popular in current society for its portability and intelligence, but excluded from life of the hearing-impaired because sounds are unavailable for them. This paper provides a framework of speech based Chinese Sign Language (CSL) Animation System on Smart Phones, which combines speech recognition and sign language animation to make phones convenient for the hearing-impaired. This paper recognizes the Chinese speech into text first, and then proposes a HMMSVM model to judge interrogative expression from the speech and rewrites the plain text as mark-up text according to the rules of Chinese Sign Language Mark-up Language (CSLML) which provides signs for recording expressive context in the text, the corresponding animation is finally synthesized using key-frame technology. The prototype system based on the framework provided in this paper gives plausible Sign Language animation.
Nonparametric predictive inference with parametric copula for survival analysis
Authors: Muhammad N , Yusoff N
Published: August 2018

Many real-world problems of statistical inference involve dependent bivariate data including survival analysis. This paper presents new nonparametric methods for predictive inference for survival analysis involving a future bivariate observation. The method combine between bivariate Nonparametric Predictive Inference (NPI) for the marginals with parametric copula to take dependence structure into account. The proposed method is a discretized version of the parametric copula. The NPI fits the marginal and very straight forward computations. Generally, NPI is a frequentist approach which infer a future observation based on past data. The proposed method resulting imprecision is robustness with regard to the assumed parametric copula in the marginal for prediction. This is practical for small data set. The suggestion is to use a basic parametric copula for small data sets. We investigate and discuss the performance of these methods by presenting results from simulation studies. The method is further illustrated via application in survival analysis using data sets from the literature.
A network topology approach to diagnose the shift of covariance structure
Authors: Yusoff Nur Syahidah , Mohamad Noryanti , Liang Chuan Zun , Sharif Shamshuritawati , Ken Tan Lit
Published: August 2018

Understanding the shift of covariance matrices in any process is not an easy task. From the literatures, the most popular and widely used test for covariance shift is Jennrich’s test and Box’s M test. It is important to note that Box and also Jennrich have constructed their own test by involving sample covariance matrix determinant or, equivalently, generalized variance (GV) as multivariate variability measure. However, GV has serious limitations as a multivariate variability measure. Those limitations of GV motivate us to use a proposed test based on an alternative measure of multivariate variability called vector variance (VV). However, if after hypothesis testing the hypothesis of stable process covariance is rejected, then the next problem is to find the cause of that situation. In this paper, network topology approach will be used to understand the shift. A case study will be discussed and presented to illustrate the advantage of this approach.
Some properties of the generalized (p,q)- Fibonacci-Like number
Authors: Suvarnamani Alongkot
Published: August 2018

For the real world problems, we use some knowledge for explain or solving them. For example, some mathematicians study the basic concept of the generalized Fibonacci sequence and Lucas sequence which are the (p,q) – Fibonacci sequence and the (p,q) – Lucas sequence. Such as, Falcon and Plaza showed some results of the k-Fibonacci sequence. Then many researchers showed some results of the k-Fibonacci- Like number. Moreover, Suvarnamani and Tatong showed some results of the (p, q) - Fibonacci number. They found some properties of the (p,q) – Fibonacci number and the (p,q) – Lucas number. There are a lot of open problem about them. In this paper, we studied about the generalized (p,q)- Fibonacci-Like sequence. We establish properties like Catalan’s identity, Cassini’s identity, Simpson’s identity, d’Ocagne’s identity and Generating function for the generalized (p,q)-Fibonacci-Like number by using the Binet formulas. However, all results which be showed in this paper, are generalized of the (p,q) – Fibonacci-like number and the (p,q) – Fibonacci number. Corresponding author: kotmaster2@rmutt.ac.th
Efficient relay selection and subcarrier assignment in cooperative OFDMA systems with QoS guarantees
Authors: Yu Zhanke , Zhang Yanhua , Guo Yan , Ni Mingfang , Zhou Jun
Published: August 2018

This paper investigates relay selection and subcarrier assignment in cooperative OFDMA systems with considerations of QoS requirements. The joint resource allocation problem is formulated as a 0-1 integer linear programming problem with the objective of maximizing the system throughput. The efficient joint optimal algorithm is proposed to tackle the problem. By using the penalty function, the complicating constraints are included in the objective function and the special model with a totally unimodular constraint coefficient matrix is constructed that could be solved rapidly as a linear programming with reduced computational complexity. Numerical results show that the proposed algorithm significantly outperforms previous works in terms of both heterogeneous services support and QoS guarantees.
The analysis of IEEE 802.11 PCF protocol based on LEO satellite Wi-Fi
Authors: He Wen , Tao Xiaofeng , Ren Defeng
Published: August 2018

In view of the problem of long propagation delay, hidden terminals and serious user conflicts in LEO satellite Wi-Fi scenario, this paper analysis the incompatibility of 802.11 DCF protocol briefly. A scheme of PCF polling mechanism based on priority is proposed and the frame format is adaptively modified. Through MATLAB simulation, the system throughput of the original scheme and the improvement scheme over the different transmission distance and nodes are analysed. The simulation results show that the improved PCF protocol can improve the throughput under the multi-user over long distances.
Study of emulsion explosive quality assessment system based on soft measurement and multilevel fuzzy evaluation
Authors: Wang Yuesheng , Huang Chenqi
Published: August 2018

Aiming at the inaccuracy and blindness of the traditional detection and assessment methods for the quality of emulsion explosives, a method for evaluating the quality of emulsion explosives based on soft measurement and multilevel fuzzy evaluation is proposed. The soft-sensing model of BP neural network can predict the online unmeasured performance indicators of detonation velocity and detonation online. The multilevel fuzzy evaluation method establishes the reliable multilevel fuzzy evaluation system based on the key parameters of the production process and expert experience. Experiments show that this soft-sensing model have made the convergence quickly and the accuracy highly,and can accurately predicts the detonation velocity and brisance of emulsion explosives online. In the last part, the design of quality assessment system can provide a new idea for solving the point of quality blindness detection and assessment.
An improved technique of clamping method for keeping coaxiality precision of rotating frame
Authors: Wu Long , Wang A M , Ren P H , Li D X
Published: August 2018

In order to ensure the concentricity accuracy of frame-like thinwalled parts, this paper takes the rotating frame as a machining example. And using the method of finite element simulation and calculation, this paper analyzes the main factors that cause the error of coaxiality of the rotating frame. Because the clamping force of the clamping device causes the deformation of the workpiece, this article is based on the finite element simulation to improve the clamping method. By adding a fixing block at the bottom of the frame and clamping with the fixing block to avoid direct pressure on the rotating frame, the error of frame concentricity caused by the clamping deformation is reduced in this way. Aiming at the error caused by machine error, this paper improves the clamping device and adds the calibration mechanism to correct the machine error and ensure the coaxial accuracy. Through the application of the improved method proposed in this paper, the concentricity error of the rotating frame can be guaranteed within 0-0.005mm.
Parametric sensitivity study of unmanned buoyancy-lifting aerial vehicle
Authors: Ma Chengjing , Zhang Caiwen , Li Guanxiong
Published: August 2018

Buoyancy-lifting aerial vehicle is a new development direction of the near space vehicle. This paper presents two conceptual schemes of unmanned buoyancy-lifting aerial vehicle with different configurations. The general parameter design method is studied, and the general parameter calculation model is established. The general parameters of airship and the buoyancy-lifting aerial vehicle are compared and studied. Taking buoyancy-lifting aerial vehicle with single fuselage and dual wings as the research object, sensitivity analysis of parameters has been done. The results show that compared with the airship, the weight of the buoyancylifting aerial vehicle with single fuselage and dual wings is reduced by 23.0%. Weight of the buoyancy-lifting aerial vehicle with dual fuselages and dual wings is increased by 55.3% compared with the aircraft with single fuselage. Lift- buoyancy coefficient and cruise speed have important influence on the general parameters of the aircraft. With the energy density of the battery increasing from 400Wh/kg to 600Wh/kg, weight of the aircraft is reduced by 58.5%. Compared with the airship, weight of the buoyancy-lifting aerial vehicle is more sensitive to the propeller efficiency.
Circular background decreases misunderstanding of multidimensional scaling results for naive readers
Authors: Degret F. , Lespinats S.
Published: August 2018

Non-linear multidimensional scaling (NL-MDS) methods are widely used to give an insight on structures of a dataset. Such a technic displays a “map” of data points onto a 2 dimensional space. The reader is expected to have natural understanding of proximity relationships between items. In our experience, MDS are especially helpful as a support for the collaboration between data analysts and specialists of other fields. Indeed, it often allows understanding main issues, major features, how to deal with data and so on. However, we observed that the classical/rectangular display of map causes confusion for non-specialists and long explanation is often required before reaching the fruitful step of the collaboration. The meaning –the absence of meaning, actually- of axes can be subject for many questions and skepticism from many naive persons. Although it is hardly quantifiable, we observed that using a circle-shaped background for maps improves the understanding of the concept of data mapping by far. We however present here a subjective feedback that may support the practical contribution of NL-MDS for other scientific fields.
The relationship of economic variables and final energy consumption: multiple linear regression evidence
Authors: Abdullah L , Leong W H
Published: August 2018

Energy consumption in developing countries is sharply increasing due to higher economic growth of industrialization along with population growth and urbanization. This paper provides a multiple linear regression evidence to illustrate the association between final energy consumption and three economic variables. Multiple linear regression analysis was used to obtain a predictive equation and to check for linearity assumption. Three input variables, viz. growth domestic product, population, and tourism are the predictors for final energy consumption. Time series yearly data of final energy consumption and the three input variables for the year 2001 until 2012 was retrieved from various databases. It is found that there was a significant variation in the final energy consumption explained by the three variables. The multiple linear regression equation indicates that the ‘population’ is the most influential variable in predicting final energy consumption.
A study on MEMS oscillators‘ frequency drift of temperature
Authors: Liu Yan , Xu Kai , Wei Meirong
Published: August 2018

The frequency output of oscillators is subject to a series of factors, such as working temperature, humidity, shock and vibration. Most of these factors are related to the manufacturing processes and packaging techniques employed in the semiconductor industry. Among the above factors, the influence of temperature is the most direct and most significant. And the effect of temperature on the frequency output of the oscillator is also called oscillators‘ frequency drift of temperature. This project aims to study frequency drift of two types of oscillators influenced by temperature, namely Quarts oscillators and MEMS oscillators. Firstly, the report states two types of oscillators‘ strength and weakness respectively. And then, referring to some industrial standards, the report also deceives and performs a series of tests to obtain data about the behavior of oscillators in different temperature. The experimental results show that the curve of the frequency-temperature of OCXO is approximately a horizontal line. And the curve of MEMS oscillator 1 looks like a capital letter M with relative small amplitude, and the curve of MEMS oscillator 2 is close to a slowly decreasing line. While the curve of crystal oscillator is a sine curve with steep rise at the end. According to the diagram, a conclusion that MEMS oscillators‘ frequency drift of temperature is less than that of crystal oscillators can be drawn naturally.
Jacketing of existing reinforced concrete structures with composites in view of seismic rehabilitation
Authors: Bouras Siham , Khamlichi Abdellatif , Attajkani Sabri
Published: August 2018

Seismic rehabilitation of pre-code existing buildings requires the choice of the method of strengthening and the determination of the amount of materials to be used optimally. Accurate evaluation of the building response in terms of its capacity at the initial state and that obtained after application of some reinforcement should be performed. For regular buildings, the nonlinear static analysis procedure constitutes a powerful tool that is used to estimate seismic performance. This procedure is characterised by its high effectiveness to account for the non-linear characteristics of the materials involved and provides a direct mean to shape the capacity curve of the construction; enabling then to make the correct decision about rehabilitation task with regards to a desired performance state. In this work, the nonlinear static pushover analysis was performed by means of ZeusNL software. Use was made of the Moroccan seismic regulations RPS2000 version 2011to determine the targeted seismic demand. Considering a four floor reinforced concrete building which is undersized with regards to actual seismic regulation, jacketing with fiber reinforced composites at different reinforcement rates was analyzed. The obtained results were expressed in terms of the lateral resistance capacity and the building tip displacement. Optimal jacketing of columns was then determined.
Effects of plies orientations and initial geometric imperfections on buckling strength of a composite stiffened panel
Authors: Feddal Ikram , Khamlichi Abdellatif , Ameziane Koutaiba
Published: August 2018

The use of composite stiffened panels is common in several activities such as aerospace, marine and civil engineering. The biggest advantage of the composite materials is their high specific strength and stiffness ratios, coupled with weight reduction compared to conventional materials. However, any structural system may reach its limit and buckle under extreme circumstances by a progressive local failure of components. Moreover, stiffened panels are usually assembled from elementary parts. This affects the geometric as well as the material properties resulting in a considerable sensitivity to buckling phenomenon. In this work, the buckling behavior of a composite stiffened panel made from carbon Epoxy Prepregs is studied by using the finite element analysis under Abaqus software package. Different plies orientations sets were considered. The initial distributed geometric imperfections were modeled by means of the first Euler buckling mode. The nonlinear Riks method of analysis provided by Abaqus was applied. This method enables to predict more consistently unstable geometrically nonlinear induced collapse of a structure by detecting potential limit points during the loading history. It was found that plies orientations of the composite and the presence of geometric imperfections have huge influence on the strength resistance.
Infrared thermography used for composite materials
Authors: Mouahid Abdelaziz
Published: August 2018

Many areas of the industry use composite materials, because of their good mechanical features in terms of low density and high mechanical strength. Composite materials are used wherever elevated rigidity and strength with reduced unit weight are required; such as wind turbine blades, shipbuilding, aeronautical and aerospace. However, the properties of composites can be hugely affected because of inside defaults such as delaminations or local cracks. Several non-destructive methods have been used for the verification of defects during construction or operation, such as ultrasound or x-ray. These methods are costly and difficult to implement. Non-destructive method using infrared thermography is considered very useful and works perfect with low cost. Two methods of non-destructive detection by infrared exists, which are (i) passive thermography, that consists of measuring infrared stream emitted by the material and (ii) active thermography, which consists of heating the material and measuring the cooling of material surface using an infrared camera. This communication describes the basic principles of both passive and active thermography, and then describes other different methods for detection of composite materials defects.
Rationale Bildgebung beim HWS-Trauma
Authors: Grieser Thomas
Published: August 2018

Die HWS ist – aufgrund ihrer hohen Mobilität – sowohl hinsichtlich ihrer knöchernen als auch ihrer diskoligamentären Integrität und Stabilität bei Akzelerations-/Dezelerationstraumen stärker gefährdet als andere Wirbelsäulenabschnitte. Dabei treten die meisten derartigen Verletzungen in der unteren HWS auf. Die konventionelle Projektionsradiografie kann weder diesen Abschnitt durchweg suffizient abbilden noch ist das HWS-Röntgen ausreichend sensitiv genug, zervikale Frakturen sicher zu erkennen. Die moderne Multislice-CT-Technik bietet sich hierzu als eine ausreichend sichere und sensitive Methode an, diesen diagnostischen Nachteil – insbesondere zur Beurteilung knöcherner Läsionen – zu überwinden. Der MRT wiederum kommt ein wachsender Stellenwert bei der Einschätzung diskoligamentärer Verletzungsmuster zu, und sie ist unverzichtbar zur Beurteilung intraspinaler Pathologien, insbesondere von traumatischen Myelonläsionen. Im Weiteren werden die für die HWS exklusiven Verletzungsmuster des kraniozervikalen Überganges einschließlich HWK II gesondert und ausführlich besprochen.
Mechanistic Pathways of Selenium in the Treatment of Graves’ Disease and Graves’ Orbitopathy
Authors: Marinò Michele , Dottore Giovanna , Leo Marenza , Marcocci Claudio
Published: August 2018

Based on the role of oxidative stress in the pathogenesis of Graves’ hyperthyroidism and Graves’ orbitopathy, the use of the antioxidant agent selenium has been proposed and several studies on the subject have been conducted, both in vitro and in vivo. Whereas a true benefit related to the use of selenium in patients with Graves’ hyperthyroidism has been questioned, its use in patients with mild Graves’ orbitopathy is generally believed to be beneficial because of which selenium has entered in the clinical practice for this eye condition.
Humidity dependence of electrostatic pick-and-place operation of a micro dielectric particle considering surface conductivity and capillary condensation
Authors: Fujiwara Ryo , Iguchi Yoji , Takahashi Kunio , Saito Shigeki
Published: August 2018

Relative humidity dependence on electrostatic pick-and-place operation is investigated to improve the reliability of micro-manipulation. The manipulation system consists of three elements: a conductive probe as a manipulator, a conductive plate as a substrate, and a dielectric particle as the target object for manipulation. To pick up/place the particle, a rectangular pulse voltage is applied to the probe. Capillary condensation at the particle-plate interface is theoretically considered to evaluate a detachment voltage (the voltage to detach the particle). Surface conductivity of the particle is theoretically considered to evaluate a detachment time (the time for detaching the particle). Experiments are conducted in relative humidities of 30%, 40%, 50%, and 60% by using a soda-lime glass particle with a diameter of 30 μm. It is clarified that the detachment voltage increases and the detachment time decreases by increasing relative humidity. The particle can be successfully picked up/placed by clarifying the effect of relative humidity on the detachment voltage and the detachment time. This knowledge, relative humidity dependence on electrostatic pick-and-place operation, will contribute to micro-fabrication technology by enhancing adaptability in various atmospheric conditions.
Interplanetary ion acoustic wave in solar wind plasma
Authors: Rehman Saeed ur , ul Haque Qamar , Shah Asif
Published: August 2018

The ion acoustic wave (IAW) and Landau damping in drifting solar wind (SW) plasma are studied kinetically. The derived dispersion relationship and Landau damping have been sketched using the Solar-Terrestrial Relations Observatory spacecraft data. In comparison to the plasma density and temperature, the plasma streaming speed is found to significantly increase the IAW phase speed. The Landau damping is found to strongly depend on the plasma density and temperature and has no dependency on the streaming speed. This study could be helpful in understanding the interplanetary IAW propagation in drifting SW plasma.
Broadening mechanisms and self-consistent gain calculations for GaN quantum cascade laser structures
Authors: Wang Ke , Grange Thomas , Lin Tsung-Tse , Wang Li , Jéhn Zoltán , Birner Stefan , Yun Joosun , Terashima Wataru , Hirayama Hideki
Published: August 2018

Carrier transport in GaN terahertz (THz) quantum cascade laser (QCL) structures is theoretically investigated using a non-equilibrium Green's function method. Although scattering due to polar optical phonons in GaN is greatly enhanced with respect to GaAs/AlGaAs THz QCLs, the phonon-induced broadening of the laser levels is found to remain much smaller than other sources of broadening arising from impurity and electron-electron scattering. The gain is calculated self-consistently accounting for the correlation effects in level broadening. Three-well based design with resonant-phonon scheme shows a peak gain of 88/cm at 10 K, and 34/cm at 280 K, which remains above the calculated loss of a double metal waveguide. The results suggest that lasing at 6.6 THz, which is beyond the traditional GaAs THz QCLs, is possible up to 280 K.
Efficient configurational-bias Monte-Carlo simulations of chain molecules with “swarms” of trial configurations
Authors: Boon Niels
Published: August 2018

The pruned-enriched Rosenbluth method (PERM) is a popular and powerful Monte-Carlo technique for sampling flexible chain polymers of substantial length. In its original form, however, the method cannot be applied in Markov-chain Monte-Carlo schemes, which has rendered PERM unsuited for systems that consist of many chains. The current work builds on the configurational-bias Monte-Carlo (CBMC) method. The growth of a large set of trial configurations in each move is governed by simultaneous pruning and enrichment events, which tend to replace configurations with a low statistical weight by clones of stronger configurations. In simulations of dense brushes of flexible chains, a gain in efficiency of at least three orders of magnitude is observed with respect to CBMC and one order of magnitude with respect to recoil-growth approaches. Moreover, meaningful statistics can be collected from all trial configurations through the so-called “waste-recycling” Monte Carlo scheme.
Impact of local arrangement of Mg and Zn atoms in rocksalt-structured MgxZn1−xO alloys on bandgap and deep UV cathodoluminescence peak energies
Authors: Onuma T. , Ono M. , Ishii K. , Kaneko K. , Yamaguchi T. , Fujita S. , Honda T.
Published: August 2018

Observation of deep ultraviolet (UV) cathodoluminescence peaks around 4.88–5.86 eV and optical transmittance measurements in the far UV spectral range enabled us to find a relatively large Stokes-like shift of 0.7–0.8 eV in rocksalt-structured (RS) MgxZn1−xO films with x = 0.61–0.92 grown on (001) MgO substrates by using the mist chemical vapor deposition method. Electronic structure calculations suggested the existence of bandgap energy (Eg) fluctuations induced by differences in the local arrangement of Mg and Zn atoms in the RS-MgxZn1−xO alloy. The Eg fluctuations and resultant exciton localization were determined to be possible origins of the large Stokes-like shift.
Influence of surface commensurability on the structure and relaxation dynamics of a confined monatomic fluid
Authors: Varadarajan Vadhana , Dasgupta Chandan , Ayappa K. G.
Published: August 2018

Molecular dynamics simulations are carried out for a single component, monatomic Lennard-Jones fluid confined between two mica surfaces to investigate the structure and relaxation dynamics of the confined fluid as a function of surface separation. Due to the underlying symmetry of the potassium ions on the mica surface, the contact layers prefer to adopt an incommensurate square or rhombic symmetry. The inner layers adopt a symmetry varying between rhombic, triangular, and square, depending on the density and surface separation. When the surface separation is an integral multiple of the particle diameter, distinct layering is observed, whereas jammed layers are formed at intermediate surface separations. This leads to the formation of both commensurate and incommensurate layering with varying intralayer symmetry. The self-intermediate scattering function exhibits a gamut of rich dynamics ranging from a distinct two-step relaxation indicative of glassy dynamics to slow relaxation processes where the correlations do not relax to zero over a microsecond for specific surface separations. An extended β relaxation is observed for both commensurate and incommensurate layering. Stretched exponential fits are used to obtain the relaxation times for the late α-relaxation regime of the self-intermediate scattering function. In some cases, we also observed dynamic and structural heterogeneities within individual layers. Although a single-component Lennard-Jones fluid does not exhibit a glass transition in the bulk, this study reveals that such a fluid can display, without supercooling, complex relaxation dynamics with signatures of a fluid approaching a glass transition upon confinement at constant temperature.
Influence of a composite free layer structure on thermal stability of perpendicular magnetic tunnel junction
Authors: Skowroński Witold , Łazarski Stanisław , Rzeszut Piotr , Ziętek Sławomir , Chęciński Jakub , Wrona Jerzy
Published: August 2018

Perpendicular magnetic tunnel junctions (pMTJs) with a CoFeB/W/CoFeB/MgO composite free layer are experimentally investigated. Magnetic anisotropy and tunneling magnetoresistance (TMR) are determined as functions of ferromagnetic (CoFeB) and capping (MgO) layer thicknesses using the ferromagnetic resonance technique. In pMTJs fabricated into 130 and 150-nm diameters, the TMR ratio > 160% and the thermal stability factor Δ > 60 are measured for the MgO capping layer thickness of tMgO ≥ 1 nm. The voltage vs. magnetic field stability diagram indicates field-free current induced switching with voltages |VS|<0.5 V.
Dynamics of flow-induced instability in gyrogravitating complex viscoelastic quantum fluids
Authors: Das Papari , Karmakar Pralay Kumar
Published: August 2018

The flow-induced excitation dynamics of electrostatic dust-streaming instability mode supported in illimitable complex gyrogravitating viscoelastic quantum plasma fluids in a spatially flat-geometry configuration is analyzed in the non-relativistic regime. The constitutive lighter electrons (larger de-Broglie wavelength) are only treated as quantum degenerate particles leaving the rest as classical. The semi-analytic formalism is based on the fabric of generalized quantum hydrodynamic model ameliorated with a dimensionality-dependent gradient correction prefactor in the electronic quantum Bohm potential. The nonlinear logatropic barotropic effects arising from fluid turbulence is included. It assumes that perturbations in the longitudinal direction do not excite any transverse mode counterparts. A standard normal mode analysis yields a linear generalized (quartic) dispersion relation. A numerical illustrative perspective is executed in the extreme hydro-kinetic regimes. Active agencies affecting the fluid stability are identified and discussed. It is seen that the quantum parameter plays a destabilizing role in both the hydro-kinetic regimes. The equilibrium dust drift acts as a stabilizing agent in both the regimes. The quantum correction prefactor introduces stabilizing and destabilizing effects in the hydro-kinetic regimes; respectively. In addition, the Coriolis rotation introduces stabilizing effect in both the regimes. Finally, implications and applications of our results in the context of gyrogravitational compact dwarf stars and their environs in are summarily outlined.
Calibration and applications of visible imaging cameras on the C-2U advanced beam-driven field-reversed configuration device
Authors: Granstedt E. M. , Fallah D. , Thompson M. C. ,   TAE Team
Published: August 2018

Two filtered, fast-imaging instruments, with radial and axial views, respectively, were used on the C-2U device to visualize line emission from impurities and hydrogenic neutrals. Novel calibration techniques needed to be developed for these instruments because the accelerated pace of C-2U operations precluded access to the interior of the vacuum vessel, targets used in typical calibration methods were not available, and in order to account for effects which have not been sufficiently addressed in the literature. Spatial calibration involved optimizing parameters in a generic camera model: ex situ using a checkerboard target and in situ using the vacuum vessel port geometry. Radiometric calibration was performed ex situ in three stages. First, the camera relative response function was mapped using an algorithm developed for high dynamic-range imaging. Second, the non-uniformity of the optical system was measured using a large LCD monitor with a characterized angular emission pattern. Finally, the absolute photon efficiency of each interference filter was determined using a calibrated uniform radiance source while also accounting for reduction in the filter transmission for off-normal rays. Periodically during the run campaign, line emission from neutral beams fired into a gas target was used as an in situ reference to check for degradation of viewport transmission. One application using calibrated camera data was tomographic reconstruction of passive impurity emission, which provided a sanity check to the excluded-flux radius inferred from wall-mounted magnetic sensors.
Tutorial: Product properties in multiferroic nanocomposites
Authors: Viehland Dwight , Li Jie Fang , Yang Yaodong , Costanzo Tommaso , Yourdkhani Amin , Caruntu Gabriel , Zhou Peng , Zhang Tianjin , Li Tianqian , Gupta Arunava , Popov Maksym , Srinivasan Gopalan
Published: August 2018

The coupling between magnetic and electric subsystems in composites of ferromagnetic and ferroelectric phases is a product property that is facilitated by mechanical strain that arises due to magnetostriction and the piezoelectric effect in the constituent phases. Such multiferroic composites are of immense interests for studies on the physics of electromagnetic coupling and for use in a variety of applications. Here, we focus on magneto-electric (ME) coupling in nanocomposites. Particular emphasis is on core-shell particles and coaxial fibers, thin film heterostructures, and planar structures with a variety of mechanical connectivity. A brief review of models that predict strong ME effects in nanostructures is followed by synthesis and characterization. Core-shell particulate composites can be prepared by hydrothermal processes and chemical or deoxyribonucleic acid-assisted assembly. Electrospinning techniques have been utilized to prepare defect free core-shell nanofibers. Core-shell particles and fibers can be assembled into superstructures with the aid of magnetic and electric fields and characterized for possible use in advanced technologies. Chemical-vapor deposition techniques have been shown to be effective for the preparation of heterostructures of ferrites and ferroelectrics. Exotic planar multiferroic structures with potential for enhancing ME coupling strengths are also considered. Scanning probe microscopy techniques are ideal for probing the nature of direct- and converse-ME coupling in individual nanostructures. Magnetoelectric characterization of assemblies of nanocomposites can be done by ME voltage coefficient, magnetic field induced polarization, and magneto-dielectric effects. We conclude with a brief discussion on possible avenues for strengthening the product properties in the nanocomposites.
Nonmodal modified Simon-Hoh instability of a plasma with a shearing Hall current
Authors: Mikhailenko V. V. , Mikhailenko V. S. , Lee Hae June
Published: August 2018

A new analytical nonmodal approach to investigate the plasma instabilities driven by sheared current is presented and applied to the analysis of the linear evolution of modified Simon-Hoh (MSH) instability of a plasma in an inhomogeneous electric field. We found analytically a strong nonmodal growth for this instability which is missed completely in the normal mode analysis. It dominates the normal mode growth when the shearing rate of the current velocity is above the growth rate of the MSH instability with a uniform current. It also includes the nonmodal growth for subcritical perturbations, which do not develop in plasmas with uniform Hall current.