bluuebunny/crossref_metadata_2025 huggingface dataset:
Calculation of hardening process parameters for locomotive parts
Authors: Buynosov Alexander , Lapshin Vasily , Smolyaninov Alexander , Dinislamov Albert
Published: October 2018

The existing theoretical models of heating by concentrated sources with a high energy density generally describe processes with deep penetration welding of part surfaces. The purpose of this study is to identify the factors that have a major effect on hardening of parts through heat treatment with a high-speed or pulsed scanning stationary heat source, which creates a uniform temperature field. Using methods of regression analysis, the authors derived equations for calculating the hardening depth in the proposed hardening process, the rate and time of steel cooling in a critical temperature range. The paper presents the calculated parameters of the hardening process in which parts, including wheel flanges of locomotives, are heated by a plasma arc in nitrogen. The findings can be used to reduce costs of complex experiments aimed at selecting surface heat hardening parameters to increase the service life of locomotive mechanical parts.
Movement of a railway car rolling down a classification hump with a tailwind
Authors: Turanov Khabibulla , Gordienko Andrey
Published: October 2018

The purpose of this paper is to calculate kinematic parameters of a railway car moving with a tailwind for designing a classification hump. The calculation of kinematic parameters is based on the d'Alembert principle, and the physical speed and distance formula for uniformly accelerated or uniformly decelerated motions of a body. By determining a difference between two components - gravitational force of a car and the resistance force of all kinds (frictional resistance, air and wind resistance, resistance from switches and curves, snow and frost resistance), which take place at different sections of a hump profile, the authors calculated the car acceleration at various types of car resistance, as well as time and speed of its movement. Acceleration, time and speed were plotted as a function of the length of a hump profile section. The research results suggest that permissible impact velocities of cars can be achieved by changing profiles of projected hump sections or by using additional hump retarders.
Dynamic loading in monitoring of brittle objects by acoustic emission method
Authors: Popkov Artem , Kochetkov Anton
Published: October 2018

Acoustic emission monitoring requires applying a force to an object. In most cases, special-purpose loading devices are used for this process; however, they are subject to some operational limitations. Dynamic loading of a controlled object makes it unnecessary to use loading devices and put the object out of operation. The purpose of the study is to develop a technique of acoustic emission monitoring under dynamic loading. The paper describes results of experiments with impact loading of a glass sheet with a crack. It proposes a method for separating the total flow of acoustic emission signals into stationary groups that are typical for different acoustic emission sources.
Development of the technical vision algorithm
Authors: Elugachev Pavel , Shumilov Boris
Published: October 2018

The purpose of the work is creation of a set of technical means (switches, sensors) for recognition of transport infrastructure facilities, including development of algorithms for autonomous operation of technical facilities under changing environmental factors. In this work, we used methods for determining the volume of a three-dimensional facilities from the data of photo and video recording of the surrounding situation. The algorithm of technical vision was obtained, which is implemented as a program on a mobile device for recognition by means of stereometry of transport infrastructure facilities and their defects and storage of transport infrastructure defects. The novelty of the research is building of decision algorithms based on devices and sensors that recognize changing road conditions, namely, defects in coverage. The data obtained can be used in the planning of road repairs, in the analysis of traffic accidents by road police, road users for processing complaints, etc.
Full-Field Vibration Measurement Using Camera Through Shearlet System
Authors: Wee C.A. , Ngali M. Z.
Published: October 2018

Traditionally, vibration measurement is done using an accelerometer or Laser Doppler Vibrometer, which is an intrusive and single point measurement respectively. This paper demonstrated vibration signal extracted from a perceptually invisible vibrating object using only a camera non-intrusively at full-field capacity. the camera that is capable to capture 1000 frames-per-second video was used to capture the motion of the vibrating object. Each frame of the video was decomposed using complex shearlet transform and the extracted signal was compared to an accelerometer. Shearlet decomposed each frame of the video into complex coefficients which were later used to recover the motion between two consecutive frames. Phase information that were used to retrieve the vibration signal were weighted to decrease unwanted noise. Resonant frequencies of a simply supported beam at 104.0 Hz, 209.5 Hz and 396.0Hz were successfully recovered. Single frequency extraction from an excited loud-speaker at specific frequencies were also conducted and showed a clear peak-to-valley frequency spectrum recovery. the potential of using camera as a full-field displacement measurement where each pixel acting as a vibrometer was explored. Full-field test to recover the mode shape of a circular membrane showed promising result with eight mode shapes successfully retrieved. the experiments proved that each individual pixel was able to retrieve motion at subpixel level that is at 0.00001 pixel scale.
Attenuation of Motorcycle Handle Vibration Using Dynamic Vibration Absorber
Authors: Saifudin Muhammad Iyad Al-Maliki , Usamah Nabil Mohamad , Ripin Zaidi Mohd
Published: October 2018

Motorcycle riders are exposed to hand-transmitted vibration of the hand-arm system due to the vibration of the handle and extended exposure can result in numbness and trembling. One feasible solution to attenuate the handle vibration is by using a dynamic vibration absorber (DVA). In this work a DVA is designed and mounted on the motorcycle handle in order to reduce the vibration at the handle by transferring the vibration from the primary system handle to the secondary mass. Removal of elastomeric material at the DVA mounting locations, symmetry of secondary mass and the direction of DVA attachment influence the vibration absorption. A series of tests conducted show that the vibration on the handle is mainly induced by the engine and there is additional source of vibration from the road surface roughness. Installation of DVA at different locations on the handle resulted in various attenuation levels at different speed in the x and z directions. the attenuation level is between 59-68 % in the biodynamic x-directions for speed at 30-50kmh-1.
Modelling of the Coupled Beam-Piezoelectric Material With Hysteresis Non-Linerity Effect
Authors: Satar Mohd Hafiz Abdul , Mazlan Ahmad Zhafran Ahmad
Published: October 2018

Hysteresis is one of the non-linearity characteristics of the piezoelectric material. This characteristic is important to be characterized since it can affect the performance of the piezoelectric material as sensor or actuator in many applications. In this study, the model of the coupled aluminium beam with single piezoelectric patch material is constructed to investigate the hysteresis effect of the piezoelectric material to the whole beam structure. A P-876 DuraActTM type piezoelectric patch material is used in modelling of the piezoelectric actuator. Firstly, the modal analysis of the coupled beam-piezoelectric actuator is determined to get the natural frequencies and mode shapes. Then, the piezoelectric patch material is investigated in terms of actuator by given a sinusoidal voltage excitation and output in terms of deflection, stress and strain of the piezoelectric actuator are investigated. From the results, it is clear that, the coupled beam-piezoelectric material is affected by the hysteresis of the piezoelectric material and the natural frequencies of the beam structure. This characteristic is important for the piezoelectric actuator manufacturer and by providing the correction algorithm, it can improve the performance of the piezoelectric actuator for many applications.
Measurement of the Hissing-Type Noise and Vibration of the Automotive HVAC System
Authors: Paiman Muhammad Abdul Rahman , Mazlan Ahmad Zhafran Ahmad , Hamdan Muhammad Hidayat , Isa Mohamad Syazwan Md. , Man Sharum , Ghapar Mohd Zukhairi Abd. , Sulaiman Mohamad Shamsul Azraf , Miyashita Tomoyuki
Published: October 2018

Noises such as hissing, humming, air-rush and compressor engagement are the common type of noises that can be induced from the automotive heating and ventilating air conditional (HVAC) system. These noises are basically generated from the effects of vibrational HVAC components. Due to this, the root cause of the noises has to be investigated for any implementation of solution. In this study, the hissing-type of noise is taken into consideration whereby the noise and vibration are measured from various HVAC components such as Evaporator Inlet and Outlet and Thermal Expansion Valve (TXV). Three types of measurement sensors are used in this study which is tri-axial accelerometer for the vibration, tachometer for the engine rpm tracking and microphone for the noise measurement. Two types of operating conditions are taken into consideration, when engine running at 850 rpm (idle) and 850-3000 rpm (tracking) conditions and a constant blower speed is applied for both conditions. the result shows that, the hissing type of noise is determined at the frequency range of 4500-5000 Hz for the both idle and running conditions, whereby the vibration at the Evaporator Inlet is the most significant compared to the Evaporator Core and TVX components. the vibration of the Evaporator Inlet shows the drastic vibration increment between 1000-1500 rpm and getting worse towards 3000 rpm. This result is validated with the 3D colour of noise waterfall analysis, whereby the hissing noise shows the dominant result in the frequency range of 4500-5000 Hz.
Calculating the Moduli Elasticity For Reinforced Concrete Using New Rule of Mixtures Approach for the Dam Structure
Authors: Zulkefli Zainordin Firdaus , Zawawi Mohd Hafiz , Hassan Nurul Husna , Zainol Mohd Remy Rozainy Mohd Arif , Abas Mohamad Aizat , Mazlan Ahmad Zhafran Ahmad
Published: October 2018

Dam is the important structure use for water domestic store, electricity power supply, irrigation and flood control. Dam deal with reinforced concrete as a main material in construction. the material considerable safe when ability to support external and internal load. the capability of dam material due to safety is effect by degradation. Prevention monitoring must be conducted for high risk structure. Thus, moduli elastic is a mechanical property to measure stiffness and had relationship between stress and strain of material. While non-destructive and destructive testing in site inspection does not include reinforce and give incorrect moduli elasticity. New approach rule of mixture (Rom) with solid work software refer to United States Department of the Interior Bureau of Reclamation (USBR) standard design for small dam, give reliability monitoring with true sustain modulus elasticity of dam structure time by time. the concrete properties for sustain of moduli elasticity standard type gravity concrete dam value is 20.684 GPa. If the value decreases drastically from the standard, high precaution must be taken.
Influence du type de démarche de fatigue multiaxiale sur la prévision de durée de vie d’un assemblage boulonné
Authors: Camara Aliou Badara , Pennec Fabienne , Laurans Emmanuel , Peyronnet Vincent , Robert Jean-Louis , Bouchaïr Abdelhamid
Published: October 2018

Ce travail présente l’étude de l’évaluation de la durée de vie en fatigue d’un joint éclissé de rail en utilisant deux critères de fatigue multiaxiaux. Le premier critère, basé sur l’approche de type plan critique, est celui de Dang Van. C’est un critère largement utilisé pour les applications industrielles en France. Pour certaines conditions de chargement, en particulier lorsque la structure est soumise à des états de contraintes non proportionnels, l’approche plan critique ne fournit pas toujours une durée de vie conservative en fatigue. C’est la raison pour laquelle un autre critère, basé sur une approche différente de fatigue multiaxiale, a été implémenté et mis en œuvre. Le second critère relève de l’approche intégrale proposée par Zenner. Ces deux critères sont programmés sur le logiciel Matlab pour le calcul de la durée de vie en fatigue multiaxiale. Des différences significatives sont obtenues selon l’approche de fatigue multiaxiale utilisée.
Adaptive fitness landscape for replicator systems: to maximize or not to maximize
Authors: Bratus Alexander S. , Semenov Yuri S. , Novozhilov Artem S.
Published: October 2018

Sewall Wright’s adaptive landscape metaphor penetrates a significant part of evolutionary thinking. Supplemented with Fisher’s fundamental theorem of natural selection and Kimura’s maximum principle, it provides a unifying and intuitive representation of the evolutionary process under the influence of natural selection as the hill climbing on the surface of mean population fitness. On the other hand, it is also well known that for many more or less realistic mathematical models this picture is a severe misrepresentation of what actually occurs. Therefore, we are faced with two questions. First, it is important to identify the cases in which adaptive landscape metaphor actually holds exactly in the models, that is, to identify the conditions under which system’s dynamics coincides with the process of searching for a (local) fitness maximum. Second, even if the mean fitness is not maximized in the process of evolution, it is still important to understand the structure of the mean fitness manifold and see the implications of this structure on the system’s dynamics. Using as a basic model the classical replicator equation, in this note we attempt to answer these two questions and illustrate our results with simple well studied systems.
A New Decomposition Basis for The Classification of Aberrations of The Human Eye
Authors: Dumas Laurent , Gatinel Damien , Malet Jacques
Published: October 2018

The optical defects of the human eye are analyzed and classified by studying the corre-sponding ocular wavefront. After presenting the orthogonal basis, called the Zernike basis, which is currently used for the wavefront analysis, a new mathematical decomposition basis is built. In this new basis, the phase errors due to the low degree aberrations terms are totally separated from the high order terms, in order to improve the relevance of the clinical interpretation through a better appreciation of the low vs high aberration wavefront components. Various clinical examples (myopia, keratoconus) clearly show the interest of this new basis compared to a diagnosis based on the Zernike decomposition.
The Deterministic Evolution Of Illicit Drug Consumption Within a Given Population
Authors: Bibi Ruhomally Yusra , Banon Jahmeerbaccus Nabeelah , Zaid Dauhoo Muhammad
Published: October 2018

We study the NERA model that describes the dynamic evolution of illicit drug usage in a population. The model consists of nonusers (N) and three categories of drug users: the experimental (E) category, the recreational (R) category and the addict (A) category. Two epidemic threshold term known as the reproduction numbers, R0 and μ are defined and derived. Sensitivity analysis of R0 on the parameters are performed in order to determine their relative importance to illicit drug prevalence. The local and global stability of the equilibrium states are also analysed. We also prove that a transcritical bifurcation occurs at R0 = 1. It is shown that an effective campaign of prevention can help to fight against the prevalence of illicit drug consumption. We demonstrate persistence when R0 > 1 and conditions for the extinction of drug consumption are also established. Numerical simulations are performed to verify our model. Our results show that the NERA model can assist policy makers in targeting prevention for maximum effectiveness and can be used to adopt evidence-based policies to better monitor and quantify drug use trends.
Synkope – Eine praktische Abklärungsstrategie
Authors: Nemeth Blanka , Weber Elisabeth , Huber Lars
Published: October 2018

Syncope is defined as a transient, self-limited loss of consciousness due to insufficient cerebral blood perfusion. In a clinical setting, syncopal events usually present a diagnostic dilemma due to its broad differential diagnosis ranging from banal to potentially harmful causes. In the absence of a working hypothesis, multiple tests are ordered that result in high costs but are of questionable diagnostic and therapeutic value. This article provides a practical overview and, based on international guidelines and selected studies, proposes a standardized approach to patients with syncope. Initial evaluation of these patients includes taking a careful medical history, physical examination and ECG. These tests result in an individual risk assessment that supports decision-making whether further analysis should be performed in an outpatient or inpatient setting. Additional tests including echocardiography, laboratory analysis, cardiac monitoring, CT-scans, are ordered according to prior evaluation. This article reviews the most common diagnostic tests, their indications and the clinical relevance for the evaluation of patients with syncopal events. Therapeutic options are not within the focus of this article.
Catalyst-Free, Metal-Free, and Chemoselective Transamidation of Activated Secondary Amides
Authors: Chandrasekaran Srinivasan , Ramkumar Rajagopal
Published: October 2018

A simple protocol, which is catalyst-free, metal-free, and chemoselective, for transamidation of activated secondary amides in ethanol as solvent under mild conditions is reported. A wide range of amines, amino acids, amino alcohols, and the substituents, which are problematic in catalyzed transamidation, are tolerated in this methodology. The transamidation reaction was successfully extended to water as the medium as well. The present methodology appears to be better than the other catalyzed transamidations reported recently.
The Excised Appendix Tip—To Send or not to Send, That is the Question
Authors: Tullie Lucinda , Vadgama Bhumita , Anbarasan Ravindar , Stanton Michael , Steinbrecher Henrik
Published: October 2018

A 9-year-old boy, with previous anorectal malformation and neuropathic bladder and bowel, underwent ileocystoplasty, Monti–Mitrofanoff and appendix antegrade colonic enema procedure. The tip of the macroscopically normal appendix was sent for routine histopathology. Microscopy demonstrated a 5-mm well-differentiated neuroendocrine tumor extending into muscularis propria. Ki-67 index was <2%. Due to margin involvement, the appendix conduit and surrounding skin were re-excised and a tube cecostomy was created through a separate incision. Microscopy revealed no residual neuroendocrine tumor, and no further treatment was required.
A Case of Inferior Vena Cava Thrombosis Induced by Left Iliac Vein Stents
Authors: Wei Wei , Jiang Xuemei , Xu Bo , Chen Yikuan
Published: October 2018

Stents have been widely used to restore the patency of the iliac vein in the treatment of its obstruction. However, various complications related to those stents have been reported. This case report covers a 67-year-old male who was diagnosed with left iliofemoral venous post-thrombotic syndrome with recurrent acute deep venous thrombosis. Thrombosis of the inferior vena cava was induced by pronounced extension of left iliac vein stents. Extending stents in this way covers the outlet of the contralateral common iliac vein and may induce thrombosis in the inferior vena cava.
Evaluation of Blood Loss and Implant Alignment after Total Knee Arthroplasty with Inertial Based Extramedullary Femoral Cutting Guide
Authors: Bonanzinga Tommaso , Tanzi Piergiuseppe , Pia Neri Maria , Iacono Francesco , Mazzola Claudio , Belluati Alberto , Colombelli Andrea , Zaffagnini Stefano , Marcacci Maurilio
Published: October 2018

Purpose The purpose of this study was to compare, in terms of blood loss and implant alignment, a new generation of smart extramedullary (EM) cutting guides with the conventional intramedullary (IM) guide for total knee arthroplasty (TKA). The hypothesis was that the EM system would result in less blood loss and fewer days of hospitalization, while ensuring equal or higher accuracy in the alignment of the femoral implant.

Methods Thirty-six patients were enrolled for the present study: 18 patients underwent TKA using the EM guide and for the other 18 patients the IM guide was used. Preoperative and postoperative X-rays were acquired. The preoperative and postoperative hemoglobin values were compared. Lastly, length of hospital stay was recorded.

Results The hemoglobin difference was significantly lower in the EM group. The alignment of the prosthetic femoral implant in the two groups was comparable but all patients in the EM cohort had a final alignment within 3 degrees of range on the frontal view, while 22% of the patients in the IM cohort had a final alignment exceeding 3 degrees of range. The mean hospitalization duration showed no significant difference between groups, though EM group showed 1.6 days less compared with IM group.

Conclusions The inertial-based EM guide system could be useful for decreasing blood loss compared with conventional guide. This device tended to have better results even in terms of accuracy, but this difference was not significant.

Level of Evidence This is a level II, prospective cohort study.
Opiate Pain Medication Consumption in Cigarette Smokers following Total Hip Arthroplasty
Authors: Etcheson Jennifer , Gwam Chukwuweike , George Nicole , Walia Naval , Jerjian Christophe , Han Ga-ram , Virani Sana , Miller Seth , Delanois Ronald
Published: October 2018

Purpose The purpose of the present study was to assess perception of pain and pain management in smokers versus nonsmokers who received a total hip arthroplasty (THA).

Methods Patients who underwent THA from 2010 to 2016 were propensity score matched 1:1 based on race, body mass index, age, and sex. This yielded 124 smokers and 124 nonsmokers. Pain intensity was quantified using area under the curve for visual analog scale pain scores. Opioid consumption was determined using a morphine milliequivalent (mEq) conversion algorithm. An independent samples t-test and Chi-square analysis was conducted to assess continuous and categorical variables respectively.

Results Smokers experienced a nonsignificantly increased pain intensity (198.1 vs. 185.7; p = 0.063). Smokers demonstrated significantly higher opioid consumption in both immediate postoperative (65.9 vs. 59.3 mEq; p = 0.045) and 90 days postoperative periods (619.9 vs. 458.9 mEq; p = 0.029).

Conclusion Our study demonstrated a nonsignificantly increased pain intensity, and (in both the immediate and 90 days postoperative periods) a significantly higher opioid consumption following THA in patients who smoke cigarettes. This may be due to a relatively small effect size, warranting the need for larger prospective studies. Nevertheless, arthroplasty surgeons should encourage preoperative smoking cessation and alternative nonopioid analgesics to smoking patients receiving THA.

Level of Evidence This is a level III, retrospective cohort study.
The Effect of Blood Loss on Cefazolin Levels in Women Undergoing Cesarean Delivery
Authors: Dotters-Katz Sarah K. , Smid Marcela C. , Grace Matthew R. , Gunatilake Ravindu P. , Sykes Craig , Blake Kimberly , Boggess Kim A. , Patil Avinash S. , Manuck Tracy
Published: October 2018

Objective To quantify the effects of operative blood loss during cesarean on tissue and plasma cefazolin concentrations.

Study Design This was a prospective observational study of singleton pregnancies undergoing scheduled cesarean between 34 and 40 weeks. Cefazolin administered prior to skin incision. Maternal plasma samples were obtained (Time 1[T1]: immediately, T2: 20 minutes, T3: 40 minutes, and T4: 60 minutes after cefazolin infusion). Subcutaneous adipose tissue sampled before and after fascia. Primary outcome was subcutaneous adipose cefazolin level after fascial closure. Formal quantitative blood loss (QBL) performed. Women with higher QBL, those at/above 75% of QBL in this population, were compared with those with lower QBL (QBL below 75%). Data analyzed using bivariable statistics.

Results Ninety-two women were screened, 32 were eligible, and 20 enrolled. Median QBL was 630 mL (interquartile range [IQR]: 473–818) and 1,160 mL (IQR: 1,000–1,560) in the low and high QBL groups, respectively. Demographics and operative characteristics were similar. Median adipose cefazolin level after fascial closure did not differ between the groups (3.5 vs. 3.9 μg/g, p = 0.75). No differences in maternal plasma cefazolin concentrations between the groups at any time point or in pharmacokinetic parameters were seen.

Conclusion Intraoperative maternal plasma concentrations and adipose levels of cefazolin are similar between women with high and low blood loss at the time of cesarean delivery.
Qualitätsmanagement: Kollegiales Peer-Review-Verfahren in der Intensivmedizin
Authors: Muhl Elke
Published: October 2018

We report on the German Peer Review procedure for the quality management of Intensive Care Wards. The third up-date of the quality-indicators was published in 2017. The Peer Review Procedure, its organization, the development of quality indicators in Germany and their benefit for the patients is introduced.
A model of Josephson junctions on Boson systems—Currents and entropy production rate
Authors: Kanda Tomohiro
Published: October 2018

Non-equilibrium steady states, in the sense of Ruelle [Commun. Math. Phys. 224, 3–16 (2001)], of Boson systems with Bose–Einstein condensation are investigated with the aid of the C*-algebraic method. The model consists of a quantum particle and several bosonic reservoirs. We show that the mean entropy production rate is strictly positive and independent of phase differences provided that the temperatures or the chemical potentials of reservoirs are different. Moreover, Josephson currents occur without entropy production, if the temperatures and the chemical potentials of reservoirs are identical.
Configurational stability for the Kuramoto–Sakaguchi model
Authors: Bronski Jared C. , Carty Thomas , DeVille Lee
Published: October 2018

The Kuramoto–Sakaguchi model is a generalization of the well-known Kuramoto model that adds a phase-lag paramater or “frustration” to a network of phase-coupled oscillators. The Kuramoto model is a flow of gradient type, but adding a phase-lag breaks the gradient structure, significantly complicating the analysis of the model. We present several results determining the stability of phase-locked configurations: the first of these gives a sufficient condition for stability, and the second a sufficient condition for instability. In fact, the instability criterion gives a count, modulo 2, of the dimension of the unstable manifold to a fixed point and having an odd count is a sufficient condition for instability of the fixed point. We also present numerical results for both small (N≤10) and large (N=50) collections of Kuramoto–Sakaguchi oscillators.
Photo-induced enhancement of the dark conductivity in nanocrystalline germanium/amorphous silicon composite thin films
Authors: Nangoi J. K. , Bodurtha K. , Kakalios J.
Published: October 2018

A light-induced increase in the dark conductivity is observed in composite thin films consisting of hydrogenated amorphous silicon (a-Si:H) containing nanocrystalline germanium (nc-Ge) inclusions, synthesized by co-deposition in a dual-chamber plasma enhanced chemical vapor deposition system. Unlike the Staebler-Wronski effect or persistent photoconductivity observed in amorphous semiconductors, this photo-induced excess conductivity is observed even in composite nc-Ge/a-Si:H films with a minimal photosensitivity. The decay of the excess conductivity follows a single-exponential time dependence, with a temperature independent time constant. We propose that spatial separation of photo-excited charge carriers by the compositional morphology present in the film, with tunneling of photo-excited holes into the germanium nanocrystalline inclusions, is involved in the creation and removal of this effect.
Effects of brain-derived neurotrophic factor and noise on transitions in temporal lobe epilepsy in a hippocampal network
Authors: Zhang Liyuan , Fan Denggui , Wang Qingyun , Baier Gerold
Published: October 2018

Brain-derived neurotrophic factor (BDNF) has recently been implicated in the modulation of receptor activation leading to dynamic state transitions in temporal lobe epilepsy (TLE). In addition, the crucial role of neuronal noise in these transitions has been studied in electrophysiological experiments. However, the precise role of these factors during seizure generation in TLE is not known. Building on a previously proposed model of an epileptogenic hippocampal network, we included the actions of BDNF-regulated receptors and intrinsic noise. We found that the effects of both BDNF and noise can increase the activation of N-methyl-D-aspartate receptors leading to excessive Ca2+ flux, which induces abnormal fast spiking and bursting. Our results indicate that the combined effects have a strong influence on the seizure-generating network, resulting in higher firing frequency and amplitude. As correlations between firing increase, the synchronization of the entire network increases, a marker of the ictogenic transitions from normal to seizures-like dynamics. Our work on the effects of BDNF dynamics in a noisy environment might lead to an improved model-based understanding of the pathological mechanisms in TLE.
Forward projection matrix derivation through Monte-Carlo ray-tracing of KSTAR infra-red imaging video bolometer (IRVB)
Authors: Oh Seungtae , Jang Juhyeok , Peterson Byron , Choe Wonho , Hong Suk-Ho
Published: October 2018

The infrared imaging video bolometer (IRVB) as a foil bolometry technique can be an alternative solution to the conventional resistive bolometer due to its electro-magnetic immunity and 2D plasma profiles. The plasma profile of the IRVB cannot be directly derived from the foil images due to the difference between the foil pixel number and the plasma pixel number and the line integrated nature of the incident rays on the foil. So, it needs tomography such as the Phillips-Thikhonov algorithm. The projection matrix constructing the foil image from the plasma very directly influences the tomography. So, the projection matrix needs to be constructed precisely. For the technique calculating the precise projection matrix, a forward Monte-Carlo ray-tracing method is proposed here, and this technique can provide the detailed descriptions of the foil image. And it can give enhanced performance in the reconstructions of the plasmas with spatially localized power.
A general framework for boundary equilibrium bifurcations of Filippov systems
Authors: Simpson D. J. W.
Published: October 2018

As parameters are varied, a boundary equilibrium bifurcation (BEB) occurs when an equilibrium collides with a discontinuity surface in a piecewise-smooth system of ordinary differential equations. Under certain genericity conditions, at a BEB, the equilibrium either transitions to a pseudo-equilibrium (on the discontinuity surface) or collides and annihilates with a coexisting pseudo-equilibrium. These two scenarios are distinguished by the sign of a certain inner product. Here, it is shown that this sign can be determined from the number of unstable directions associated with the two equilibria by using techniques developed by Feigin. A normal form is proposed for BEBs in systems of any number of dimensions. The normal form involves a companion matrix, as does the leading order sliding dynamics, and so the connection to the stability of the equilibria is explicit. In two dimensions, the parameters of the normal form distinguish, in a simple way, the eight topologically distinct cases for the generic local dynamics at a BEB. A numerical exploration in three dimensions reveals that BEBs can create multiple attractors and chaotic attractors and that the equilibrium at the BEB can be unstable even if both equilibria are stable. The developments presented here stem from seemingly unutilised similarities between BEBs in discontinuous systems (specifically Filippov systems as studied here) and BEBs in continuous systems for which analogous results are, to date, more advanced.
A liquid VI scintillator cell for fast-gated neutron imaging
Authors: Geppert-Kleinrath Verena , Freeman Matthew S. , Hurlbut Charles R. , Merrill Frank , Tinsley James R. , Volegov Petr , Wilde Carl
Published: October 2018

The design of a new fast-gated neutron imaging system for the National Ignition Facility with much stricter timing constraints than a previous system has prompted the search for a fast scintillator material that can be used in imaging. A novel imaging cell based on Liquid VI has recently been developed with Eljen Technology and characterized at the Special Technologies Laboratory and the Los Alamos Neutron Science Center. The results show superior timing characteristics and spatial resolution, and sufficient light production for the new system compared to fast plastic scintillators previously used in neutron imaging. While the primary application is in inertial confinement fusion diagnostics, the imaging cell can be used in any fast-gated imaging application where timing characteristics and spatial resolution are of concern.
Elastic properties of SmPt2Cd20 probed by ultrasound measurements
Authors: Nakanishi Yoshiki , Nakamura Kazuto , Nakamura Masahiro , Taniguchi Masaya , Nakamura Mitsuteru , Yoshizawa Masahito , Yamada Akira , Higashinaka Ryuji , Matsuda Tatsuma D. , Aoki Yuji
Published: October 2018

Ultrasound measurements have been carried out to investigate the elastic and low-temperature 4f-electronic properties of the Sm-based 1-2-20 system SmPt2Cd20. It was found that SmPt2Cd20 shows a pronounced elastic softening toward the magnetic transition temperature Tc = 0.64 K in the temperature dependence of the transverse elastic constant CE = (C11 -C12)/2. The clear elastic softening behavior is suppressed gradually with increasing a magnetic field. The obtained results can be explained reasonably by a deformation potential approximation in which a coupling between conduction electrons and elastic strains caused by sound waves leads to a temperature dependence of elastic constants. This suggests possibly that the 4f electrons would become itinerant in the ground state in SmPt2Cd20. The nature of the low-temperature elastic and electronic states involving the ground state multiplets of Sm ions are discussed.
Chaos versus noise as drivers of multistability in neural networks
Authors: Orio Patricio , Gatica Marilyn , Herzog Rubén , Maidana Jean Paul , Castro Samy , Xu Kesheng
Published: October 2018

The multistable behavior of neural networks is actively being studied as a landmark of ongoing cerebral activity, reported in both functional Magnetic Resonance Imaging (fMRI) and electro- or magnetoencephalography recordings. This consists of a continuous jumping between different partially synchronized states in the absence of external stimuli. It is thought to be an important mechanism for dealing with sensory novelty and to allow for efficient coding of information in an ever-changing surrounding environment. Many advances have been made to understand how network topology, connection delays, and noise can contribute to building this dynamic. Little or no attention, however, has been paid to the difference between local chaotic and stochastic influences on the switching between different network states. Using a conductance-based neural model that can have chaotic dynamics, we showed that a network can show multistable dynamics in a certain range of global connectivity strength and under deterministic conditions. In the present work, we characterize the multistable dynamics when the networks are, in addition to chaotic, subject to ion channel stochasticity in the form of multiplicative (channel) or additive (current) noise. We calculate the Functional Connectivity Dynamics matrix by comparing the Functional Connectivity (FC) matrices that describe the pair-wise phase synchronization in a moving window fashion and performing clustering of FCs. Moderate noise can enhance the multistable behavior that is evoked by chaos, resulting in more heterogeneous synchronization patterns, while more intense noise abolishes multistability. In networks composed of nonchaotic nodes, some noise can induce multistability in an otherwise synchronized, nonchaotic network. Finally, we found the same results regardless of the multiplicative or additive nature of noise.
Numerical simulations and experiments on thermal viscous power dissipation of perforated plates
Authors: Li Lijun , Gang Xianyue , Liu Yiran , Zhang Xianxu , Zhang Fan
Published: October 2018

The micro-perforated plates (MPPs) are widely used in sound absorption structures. As perforations become smaller, the energy loss caused by viscous dissipation and thermal radiation of the medium should be considered on calculation and design of the MPPs. In this paper, the energy loss of thin tube, micro tube and capillary tube are analyzed by using the finite element method (FEM). The acoustic finite element models of MPPs are created, and the power dissipation, impedance, resonant frequency, absorption coefficient and correction length of perforated plates are analyzed. The impedance experiments are carried to test the numerical results. This paper approves that the energy loss caused by thermal and viscous should be considered on MPPs, which is determined by air viscous, and affected by the diameter of perforations, porosity and frequency. The resonant frequency is affected by viscous. The theoretical formula of Helmholtz resonator cause great error for micro-perforated plates usage, and it should be calculated by numerical simulation in the field of MPPs design and application.
A table-top EUV focusing optical system with high energy density using a modified Schwarzschild objective and a laser-plasma light source
Authors: Zhang Zhe , Li Wenbin , Huang Qiushi , Zhang Zhong , Yi Shengzhen , Pan Liuyang , Xie Chun , Wachulak Przemyslaw , Fiedorowicz Henryk , Wang Zhanshan
Published: October 2018

For investigating extreme ultraviolet (EUV) damage on optics, a table-top EUV focusing optical system was developed in the laboratory. Based on a modified Schwarzschild objective with a large numerical aperture and a laser-plasma light source, this optical system can generate a focusing spot with the maximum energy density of 2.27 J/cm2 at the focal plane of the objective at the wavelength of 13.5 nm. The structures and the characterized properties of this optical system are presented in this paper. For testing the performance of this setup, single-shot EUV damage tests were carried out on an optical substrate of CaF2 and a gold thin film. The damage thresholds and morphologies of these samples were given and discussed with former research studies.
Origin of tri-state resistive switching characteristics in SiCN thin films for high-temperature ReRAM applications
Authors: Singh Narendra , Kaur Davinder
Published: October 2018

In the present work, the resistive switching (RS) properties of Ag/SiCN/Pt and W/SiCN/Pt devices having electrochemically active (Ag) and inactive (W) top electrodes have been systematically investigated. Both devices revealed stable and reproducible bipolar resistive switching characteristics. The W/SiCN/Pt device exhibits two-state resistive switching behavior, i.e., low resistance state (LRS) and high resistance state (HRS), whereas the Ag/SiCN/Pt device shows tri-state RS characteristics [LRS, intermediate resistance state, and HRS)]. The two resistance state RS characteristics of the W/SiCN/Pt device were ascribed to conduction path formation/rupture via electron trapping/de-trapping in nitride-related traps. However, the tri-state RS behavior of the Ag/SiCN/Pt device could be attributed to conduction path formation via electron trapping in nitride-related traps followed by an additional Ag filament growth between the top and bottom electrodes. The origin of tri-state switching in the Ag/SiCN/Pt device and Ag filament formation were well explained by a conceptual model and the temperature and cell area dependence of the resistance measurement. The Ag/SiCN/Pt device exhibits good reliable properties such as endurance of ∼105 cycles and long retention time ∼105 s at a high temperature of 200 °C. This comprehensive study suggests that nonvolatile multi-level (three-level) resistive switching in the SiCN-based device can be achieved by the formation of different types of conducting filaments sequentially and the Ag/SiCN/Pt device could be capable of futuristic multi-bit storage resistive random access memory which can operate at high temperature.
The effective point charge of probe tip in piezoresponse force microscopy
Authors: Ming W. J. , Zhu R. K. , Pan K. , Liu Y. Y. , Lei C. H.
Published: October 2018

Abrasions of the probe apexes always happen during piezoresponse force microscopy (PFM) experiments, resulting in variation of distribution of the electroelastic field in piezoelectric materials, which finally influences the spatial resolution of PFM. In this paper, we find the effective point charges coupled with the piezoelectric coefficients for three probe models including the modified point charge model, the sphere-plane model, and the disk-plane model, through the fully-coupled electromechanical method. It is proved that the wear of the probe apex induces spreading of electroelastic field from the contact area to the surrounding area, and the electroelastic fields computed using the coupled method are much more localized than that computed by the decoupled method. The piezoresponses underneath the probe apexes have no correlation with the geometries of the probes, yet strongly depend on the choices of calculation methods. This analysis paves new ways for studies of the piezoresponses in complicated domain structures in ferroelectric materials.
Smoothed particle hydrodynamics (SPH) modeling of fiber orientation in a 3D printing process
Authors: Bertevas Erwan , Férec Julien , Khoo Boo Cheong , Ausias Gilles , Phan-Thien Nhan
Published: October 2018

We present a numerical study of the fused deposition modeling 3D printing process of fiber-reinforced polymers by means of Smoothed Particle Hydrodynamics (SPH). For this purpose, a classical microstructure-based fiber suspension model coupled with a constitutive model for the suspending polymer is implemented within an SPH framework. The chosen model is reviewed, together with the details and specificities of its implementation in SPH. The results for several representative cases are then presented, mainly in terms of contours of fiber orientation tensor components and orientation distributions across the deposited layer thickness. The impact of the fiber concentration and its aspect ratio in a semi-concentrated regime and the effect of the ratio between extrusion and substrate velocities are investigated. Some insights into the link between the flow field and fiber orientation evolution within the printing head and as the material exits the nozzle are given. The main findings lie in the prediction of a skin/core structure in the deposited layer in which the skin regions exhibit a higher fiber alignment with respect to the core region. This effect is found to be enhanced by an increase in fiber concentration and to be sensitive to the substrate-to-extrusion velocity ratio. It is indeed enhanced in cases where the substrate velocity is low compared to the extrusion velocity and accompanied by a larger swelling of the deposit at the nozzle exit.
Contact properties of a vdW heterostructure composed of penta-graphene and penta-BN2 sheets
Authors: Zhao Kexian , Guo Yaguang , Wang Qian
Published: October 2018

Recently, many efforts have been devoted to the study of 2D van der Waals (vdW) heterostructures because of their potential applications in new functional electronic and optoelectronic devices. Here, we propose a vdW heterostructure composed of the recently identified semiconducting penta-graphene (PG) and metallic penta-BN2 (P-BN2) monolayers. State-of-the-art theoretical calculations reveal that the intrinsic electronic properties of PG and P-BN2 are well preserved in the heterostructure, an n-type Schottky barrier forms at the vertical interface between the two layers, and a negative band bending occurs at the lateral interface of the heterostructure and the PG monolayer. In addition, strain can be used to effectively tune the Schottky barrier. Both the Schottky barriers of electron and hole increase with stretching and decrease with compressing. More interestingly, the Schottky contact can be tuned from n-type to p-type when the interlayer distance between PG and P-BN2 in the heterostructure is changed, showing a flexible controllability in device applications.
Inversion asymmetry potential tuning of topological insulator dots with impurities
Authors: Li Guo , Yang Ning , Zhu Jia-Lin , Lu Junqiang , Wu Jian
Published: October 2018

By proposing an effective method for the coupled modified Dirac equation, the effects of structure inversion asymmetry on the confined states in quantum dots of three-dimensional topological ultrathin films are investigated. It is found that the presence or absence of the quantized edge states can be controlled by the inversion asymmetry potential. The tuning of the potential to the spins of edge and nonedge states is quite different. In the presence of impurities, the mixing between the edge and nonedge states can be largely enhanced and effectively tuned by the potential. The finding will be useful to design relevant nanodevices.
Phenomenon analysis and state classification of surface discharge on oil-impregnated pressboard under AC-DC combined voltage
Authors: Li Xudong , Huang Zhengyong , Li Jian , Jiang Tianyan , Mehmood Muhammad Ali , Hou Shubin
Published: October 2018

Surface discharge may cause irreversible damage to turn-to-ground insulation in valve windings of converter transformer, where withstand with AC-DC combined voltage. This paper analyzes the phenomenon and characteristics of surface discharge on oil-impregnated pressboard (OIP) under AC-DC combined voltage, and develops a discharge state recognition method. The cylinder-plate discharge model was used to simulate surface discharge. The results showed that discharge development and OIP failure were significantly accelerated by white marks on OIP which were essentially gaseous channels. The discharge characteristics before and after white mark occurrence were both dominated by AC component because of its bigger contribution to electrical field distribution (EFD), and the DC component had obvious effect on accelerating OIP failure. A set of features representing discharge state after white mark occurrence was selected out by the entropy weight method (EWM), based on which the discharge process was classified into three states (stable, fast development and pre-breakdown state) by fuzzy C means clustering method (FCM). A support vector machine (SVM) classifier to recognize discharge state was trained and showed a good performance, whose average assessment accuracy was up to 91.98%. Moreover, the ratio between negative and positive discharge numbers could be used as an auxiliary indicator of pre-breakdown state.