bluuebunny/crossref_metadata_2025 huggingface dataset:
Mathematical simulation of operation of multi-chamber arrester for lightning protection of power lines: calculation of thermophysical properties of nonequilibrium plasma
Authors: Ivanov Dmitriy , Skornyakov Vladimir , Savelieva Irina , Korotkikh Mikhail , Shestakov Vyacheslav , Uhrlandt Dirk , Podporkin Georgy
Published: December 2018

Protection of important energy facilities from direct lightning impact requires the creation of special devices for lightning protection in particular multi-chamber arresters. To improve the efficiency of multi-chamber arrester operation it is necessary to perform mathematical simulation of the physical processes that take place inside such devices. To develop a mathematical model of arc discharge it is necessary to know the thermodynamic and transport properties of the plasma depending on temperature and pressure. In the article the dependences of the thermodynamic and transport properties of plasma in a multi-chamber arrester were obtained for the two-temperature plasma model for the electron temperature range Te = 300–30 000 K, the nonequilibrium degree range is 1–5, and the pressure range p = 0.3–1 atm.
Lightweight steel concrete structures slab panels load-bearing capacity
Authors: Rybakov Vladimir , Seliverstov Anatoly , Petrov Denis , Smirnov Andrei , Volkova Anna
Published: December 2018

Lightweight steel concrete structures (LSCS) - an innovative building structure type that can be used both as load-bearing and as enclosing one. They consist of profiled steel usually galvanized and cold-bent - filled with a monolithic foam concrete with a 200kg/m3 density, and with fiber cement sheets sheathing. These structures can be used in industrial and civil buildings as internal and external bearing and enclosing wall structures, and as slabs. According to the LSCS production method, prefabricated panels (walls and slabs) and building site performed constructions are distinguished. The article presents the LSCS subspecies, representing slabs panels made of galvanized profiled steel, density medium grade D400 monolithic foam concrete and sheets “Steklotsem” sheathing, bearing capacity experimental studies results. The paper confirms that such panels can be used in civil buildings and withstand the appropriate load, regulated by the current codes and rules. Moreover, it has been experimentally proved that the foam concrete, despite its own extremely low strength class, actually includes in the operation, preventing such effects as stability local loss, crushing and profile steel elements cross-section warping and increases the slabs overall load capacity by 20-25%.
Ansys CFX numerical study of stages centrifugal compressor with low-flow rate coefficient
Authors: Yablokov Aleksey , Yanin Ivan , Danilishin Aleksey , Zuev Anatoliy
Published: December 2018

The article presents results of applying the methods of computational fluid dynamics for model low-flow rate stages of centrifugal compressors with flow rate coefficient F = 0.028. The computational domain of a model centrifugal compressor for CFD-simulation consists of the following elements: inlet chamber, impeller, vaneless diffuser, return channel, outlet chamber, shaft seal labyrinth, front and back shroud leakage. Full-scale experimental studies were conducted to model stage 028 in air at an inlet pressure of p* = 1 atm. Numerical research for stage 028 held with flow rate coefficient F=(0.019-0.046) for three variants trailing edge of the impeller. According to the results of numerical research are constructed performances of stages centrifugal compressor and conducted verification of results. Estimated discrepancy between the results of numerical researches on the model with shaft seal labyrinth and without shaft seal labyrinth.
Implementation of the mechanistic wall boiling model in IC engine cooling gallery simulation
Authors: Abyzov Oleg , Galyshev Yuri , Metelev Andrey
Published: December 2018

The ever increasing power rates of modern IC engines pose a great challenge for maintaining the optimal temperature conditions. The current trend in the thermal management of IC engines is to utilize the limited and controlled nucleate boiling to achieve higher heat transfer rates. The modern CFD instrumentation offers a wide range of methods for predicting nucleate and film boiling. Of the available models the mechanistic RPI wall boiling model is selected in present paper in the cojuntion with the Eulerian multiphase model available in ANSYS Fluent solver to simulate subcooled nucleate boiling in engine cooling jacket.Results obtained from the simulation of boiling flow in cooling passages is then compared with the experimental data from author’s previous work and show a decent agreement.
Experimental studies and numerical simulation of coolant hydrodynamics in the inlet area of nuclear reactor fuel assembly
Authors: Dmitriev Sergei , Khrobostov Alexander , Legchanov Maksim , Dobrov Alexander
Published: December 2018

An innovative core with an increased energy resource was used when designing RITM-200 reactor unit. The paper presents the results of experimental and numerical simulation of hydrodynamic processes occurring in the inlet region of the RITM reactor fuel assembly model. Computational mesh of fuel assembly, containing ~ 22 million elements was created using Ansys ICEM CFD. The values of relative axial velocities in several cross sections at the inlet to the bundle of fuel elements are obtained. At the inlet to the fuel rods bundle the velocity field is not uniform, due to the complex geometry of the fuel assembly. The obtained results of CFD-simulation can be used to determine the input boundary conditions for subchannel programs of the core thermal-hydraulic analysis. This allows taking into account uneven flow rate distribution in subchannels due to the complex geometry of the fuel assembly inlet region.
Analog-to-digital conversion that allows to increase the dynamic range a standard ADC using the properties of electrical signals
Authors: Gritsutenko Stanislav
Published: December 2018

A method is proposed to significantly increase the dynamic range of current and voltage meters in the traction networks of railway transport. The method is based on the low entropy of signals of this type and is based on the calculation of samples whose amplitude was distorted due to the output beyond the ADC dynamic range. The approach with the solution of system of linear equations is considered. An approach without solving a system of linear equations is presented. The accuracy of the method is discussed at the end of the article.
Study of the aerodynamic regime of the cooling system of the foundations of buildings on the filling soil in the conditions of the Far North
Authors: Ivanov Victor , Ivanova Anastasiya
Published: December 2018

During construction in the Far North, due to the preservation of permafrost soils, the buildings are arranged on piles and foundations on the bedding soil. In the foundations of buildings for a smaller impact on the ground and prevention from defrosting of the soil, air cooling systems with cooling pipes are provided. Seasonal and daily variations in the temperature of the outside air and intensity of solar radiation cause fluctuations in the temperature regime of the upper layers of the soil. As a result of transformation of natural soils into technogenic, its physical properties change significantly when exposed to negative temperatures. Freezing of the soil thawed out over the summer and its further cooling is achieved by passing cold air in the winter through the air channels. The cooling system must provide the position of the upper surface of the frozen soil state under the building, as adopted by the project.

This paper discusses the aerodynamic mode of the air cooling system for foundations on bedding in permafrost soils during the construction of various buildings and structures while preserving the base soils in a frozen state and using natural cold of the outside air, which will improve the reliability of permafrost bases. An engineering method has been developed for calculating the heat fluxes of soil and pipeline laid in thickness. A technique for engineering calculation of change in the thermal regime depending on the parameters of the outside air is given, which will make it possible to usefully use the energy of the cold enclosed in the ground to warm the outside air.
New fire retardant compositions for fire-resistant automatic curtains
Authors: Nikitina Maria , Ustinov Andrey , Kiseleva Viktoria , Babikov Igor
Published: December 2018

The paper overviews the way by which intumescent fire retardant compositions act as fillers in fire-resistant automatic curtains. A several intumescent compositions, which form a heat-isolating charred layer when they are exposed to high temperatures, were produced and applied to the mineral-fabric basis of the curtain. Fire-protective properties of produced materials were assessed and compared with foreign specimens. Swelling coefficient and material’s fire durability were considered as operating parameters. The developed specimen which performed the best during fire tests was sent to accredited laboratory. It was proven, using standardized methods, that it’s fire resistance limit reaches 30 minutes. This proves an effective contribution of an intumescent compound and opens new ways of using them in fire curtains manufacturing.
Root rot grain crops on Cereals caused by the phytopathogenic fungi
Authors: Grebenikova Nadezhda , Korshunov Alexander , Rud’ Vasily , Savchenko Ivan , Marques Marcia
Published: December 2018

Researching the special and infraspecial structure in causative agent populations of the most dangerous diseases root rots of cereals in various regions of the Russjan Federation has been carried out. The defeat of cereals root rots old in Russia causes in the a complex patogenic. More often meet Fusarium culmorum (W.G.Sm.) Sacc., F. oxysporum (Schlecht.) Snyd.et Hans., F. heterosporum Nees., F. sporotrichiella nom.nov. Bilai F. gibbosum App.et Wr.emend Bilai., F. avenaceum (Fr.) Sacc. and Bipolaris sorokiniana (Sacc.) Shoem., Alternaria spp.
Optimal triple configurations of stationary shocks
Authors: Chernyshov Mihail , Tyapko Alexandr
Published: December 2018

The triple configurations of stationary shock waves with negative slope angle of the reflected shock to the velocity vector of the supersonic stream before the triple point (“inverse” triple configurations) are considered. “Inverse” configurations with maximum relations of flow parameters at the slipstream after triple point are determined. Extreme relations of the flow parameters downstream the “inverse” configurations are compared with the parameters achieved on the whole set of the triple-shock configurations that appear in supersonic streams of the inviscid perfect gas.
Experimental study of the supercritical water oxidation process within the framework of solving the task of chemical production industrial water runoff treatment
Authors: Aetov Almaz , Mazanov Sergei , Zaripov Zufar , Gumerov Farid
Published: December 2018

The given paper presents results of an experimental study of the industrial water runoff oxidation within the propylene epoxidation process carried out under supercritical fluid conditions (T=653-723 K, P=29-32 MPa) at a continuous operation installation using atmospheric oxygen as the oxidizing agent. Efficiency of the water runoff oxidation depending on the thermodynamic conditions of oxidation reaction was established. Solid residue elemental composition was determined.
Testing of the SOLPS-ITER code at Globus-M2 spherical tokamak with detached divertor
Authors: Sorokina Daria , Senichenkov Ilya , Vekshina Elena , Rozhansky Vladimir
Published: December 2018

In according to a present understanding of Scrape-Off Layer (SOL) physics, future thermonuclear devices like ITER, DEMO and beyond, require high radiation regimes in order to reduce heat loads on tokamak divertor. Recent experiments at ASDEX Upgrade, JET and other tokamaks demonstrated that such regimes might be achieved by the seeding of the radiative impurities. In the present paper the modeling of the high radiation regimes and the transition to the detachment at the Globus-M2 spherical tokamak is performed by the SOLPS-ITER transport code. The obtained modeling results for GLobus-M2 tokamak demonstrate the trend similar to what is observed at larger machines, e.g. AUG and JET. The significant reduction of peak power density at the outer target plate and transition to the detachment with High Field Side High Density (HFSHD) formation at the inner plate was achieved with impurity seeding rate almost equal to the deuterium puff (in el/sec). However, unlike AUG, further increasing of the seeding rate leads not to a formation of the radiative X-point, but to a radiative collapse. This is caused by smaller machine size, which allows the impurity neutrals to penetrate easier into the confined region. It was noticed that starting with attached divertor the inner target transits to the detachment earlier than the outer one.
Cooling of a battery pack of a car, working on renewable energy
Authors: Kasatkin Ivan , Egorov Mikle , Kotov Evgeny , Zakhlebaev Evgeny
Published: December 2018

The aim of the work is to choose a method of a solar car battery cooling. The student engineering team of Peter the Great Petersburg Polytechnic University designs the car. The analysis of the electrical circuit of the battery is carried out, the heat release is estimated due to three factors. According to the conditions of reliable operation of the battery, it is necessary to maintain its temperature range below 45°C, which requires cooling. The paper analyzes the possibilities of liquid, air-cooling, compares the free and forced methods of convective heat transfer. For the normal operating mode of the electric vehicle, environmental temperature at the level up to 38°C, a criterion thermal engineering calculation of the forced air-cooling of the corridor assembly of 405 battery cells providing the required heat dissipation is performed. It is shown that relatively high values of the heat transfer coefficient are provided under turbulent flow conditions characterized by Reynolds criteria above 103. On the basis of an analysis of the steady-state stationary heat-removal regime, it was concluded that an air flow provides a temperature gradient, sufficient for cooling the lithium-ion battery of a Solar Car «Polytech Solar».
Treatment of canine sarcoptic mange with afoxolaner (NexGard®) and afoxolaner plus milbemycin oxime (NexGard Spectra®) chewable tablets: efficacy under field conditions in Portugal and Germany
Authors: Hampel Verena , Knaus Martin , Schäfer Jürgen , Beugnet Frederic , Rehbein Steffen
Published: December 2018

The efficacy of NexGard® and NexGard Spectra® against sarcoptic mange in dogs was evaluated in a clinical field study. Skin scrapings from dogs presenting signs suggestive of sarcoptic mange were examined to confirm infestation. A total of 106 dogs were screened at eight sites in Portugal and Germany. In all, 80 dogs that had demonstrated ≥5 live Sarcoptes mites in five skin scrapings were enrolled, scored for specific clinical signs (pruritus; papules and crusts; alopecia), and allocated at random to receive either NexGard® or NexGard Spectra® twice, one month apart per label instructions. To determine efficacy, live Sarcoptes mites in five skin scrapings per dog were counted, and clinical signs were scored one month and two months after first treatment and compared to pre-treatment (baseline) values. Based on compliance, 65 dogs were determined to be evaluable cases at the end of the study. The efficacy, in terms of reduction of geometric mean live Sarcoptes mite counts, was 98.9% and 99.7% for NexGard®-treated (n = 38) and 99.6% and 100% for NexGard Spectra®-treated dogs (n = 27) at one month and two months after treatment initiation (p < 0.001, both treatments). Both treatments resulted in a significant improvement in pruritus, papules and crusts, and alopecia one month and two months after treatment initiation (p = 0.0001, both treatments). In conclusion, this field study confirms that both NexGard® and NexGard Spectra® administered twice one month apart provide an effective and safe treatment against sarcoptic mange in dogs.
Neue europäische Synkopen-Leitlinie – was ist für die Praxis wichtig?
Authors: Stockburger Martin
Published: December 2018

In diesem Frühjahr wurde eine umfangreiche Aktualisierung der im Jahr 2015 neu gestalteten Leitlinie der European Society of Cardiology (ESC) zur Diagnostik und Behandlung von Synkopen auf dem Kongress der European Heart Rhythm Association (EHRA) vorgestellt und im European Heart Journal publiziert 1. Die Leitlinie wurde unter breiter multidisziplinärer Beteiligung (Innere Medizin/Kardiologie/Physiologie/Notfallmedizin/Neurologie/Geriatrie/Pflegewissenschaften) erarbeitet. Als Hauptanliegen der Aktualisierung wird die Erleichterung der praktischen Anwendung vorhandenen Wissens zur Ätiologie und Risikobewertung von Synkopen und zu medizinisch wie auch ressourcenbezogen angemessenen diagnostischen und therapeutischen Strategien formuliert. Im klinischen Alltag bereitet die angemessene Einschätzung von Patienten mit Synkopen und die Anwendung geeigneter, also weder überdiagnostischer noch nachlässiger Diagnosestrategien nicht selten weiterhin Probleme. Neben der umfangreichen und ausgesprochen übersichtlich gehaltenen Synopsis zu allen Aspekten des kurzfristigen und reversiblen Bewusstseinsverlusts im Haupttext der Leitlinie wurde erstmals ausführliches praxisanleitendes Zusatzmaterial zur Verfügung gestellt 2. Dieser Artikel fasst wesentliche Inhalte und Handlungsempfehlungen der Leitlinie zusammen.
Palladium-Catalyzed Asymmetric Allylic Alkylation Strategies for the Synthesis of Acyclic Tetrasubstituted Stereocenters
Authors: Trost Barry , Schultz Johnathan
Published: December 2018

Over the past 20 years, the asymmetric synthesis of acyclic tetrasubstituted stereocenters by Pd-catalyzed asymmetric allylic alkylation (Pd-AAA) strategies has seen considerable growth. Despite the inherent difficulty in accessing acyclic tetrasubstituted stereocenters, creative approaches toward this problem have resulted in high stereoinduction on both electrophilic and nucleophilic reaction partners. Much of this chemistry has paved the way for unique solutions in Mo-, Ir-, and Rh-AAA, with many complimentary methods arising due to the unique regiochemical outcomes of AAA outside of Pd catalysis.

1 Introduction

2 Stereocontrol on Prochiral Electrophiles

3 Stereocontrol on Prochiral Nucleophiles

4 Temporary Cyclic Pronucleophiles

5 Allylic Alkylation with Other Metals

6 Conclusions and Outlook
Twofold Ferrocene C–H Lithiations For One-Step Difunctionalizations
Authors: Erb William , Mongin Florence
Published: December 2018

For some aromatics, a twofold C–H deprotolithiation can be achieved, allowing these compounds to be subsequently difunctionalized in one step. This short review brings together examples in which ferrocenes are converted in this way.

1 Introduction

2 Bare Ferrocene

3 Ferrocenes Substituted by Alkyl or Silyl Groups

4 Ferrocenes Substituted by Aminoalkyls

5 Ferrocenes Substituted by Halogens or Oxygen-Based Groups

6 Ferrocenes Substituted by Alkoxyalkyls or Acetals

7 Ferrocenes Substituted by Sulfoxides

8 Ferrocenes Substituted by Oxazolines

9 Ferrocenes Substituted by Carboxamides

10 Conclusion
Nickel-Catalyzed Highly Atom-Economical C–C Coupling Reactions with π Components
Authors: Xiao Li-Jun , Ye Meng-Chun , Zhou Qi-Lin
Published: December 2018

This account describes our latest advances in the field of nickel(0)-catalyzed hydrofunctionalization of π components. All reactions proceed either through internal hydride transfer or by using an external proton as the hydride source, thereby eliminating the use of stoichiometric amounts of reductants or oxidants. These nickel-catalyzed atom-economical coupling reactions demonstrate that nickel not only is an inexpensive metal catalyst, but also possesses unique and versatile catalytic abilities. Current limitations and the outlook of these reactions are also discussed.

1 Introduction

2 Nickel(0)-Catalyzed Hydroacylation of Styrenes with Simple Aldehydes

3 Nickel(0)-Catalyzed Hydroalkenylation of Imines and Aldehydes with Alkenes

4 Nickel(0)-Catalyzed Hydroarylation of Styrenes and 1,3-Dienes with Organoboronic Derivatives

5 Nickel(0)-Catalyzed Hydroalkylation of 1,3-Dienes with Simple Ketones

6 Summary and Outlook
Diagnostic and Therapeutic Endoscopy: An Overview
Authors: Fathalizadeh Alisan
Published: December 2018

As surgical and interventional techniques are becoming progressively less invasive, the role of endoscopic practices is evolving. Upper and lower endoscopy can be employed for diagnostic purposes, screening and surveillance practices, and for therapeutic interventions. The most frequently applied different indications, tools, and techniques for the various uses of endoscopy will be discussed.
Management of Spontaneous CSF Rhinorrhea: An Institutional Experience
Authors: Keshri Amit , Jain Rajat , Manogaran Ravi Shankar , Behari Sanjay , Khatri Deepak , Mathialagan Arulalan
Published: December 2018

Introduction Cerebrospinal fluid (CSF) rhinorrhea is the leakage of CSF through nasal cavity, due to abnormal communication between the arachnoid membrane and nasal mucosa. Middle-age (fourth to fifth decade) group, female gender, and obesity (body mass index > 40) are the most commonly reported risk-factors for this rare entity. In this study, we present our single center experience of spontaneous CSF rhinorrhea discussing important clinicoradiological aspects in preoperative evaluation and nuances in the endoscopic repair technique.

Material and Methods A retrospective study conducted for 43 spontaneous CSF rhinorrhea patients admitted between Jan 2011 to Jan 2018 at our tertiary care center. All patients underwent endoscopic repair of the defect depending upon their site of leak.

Results Mean age in our study was 36.7 ± 12.3 years (range: 9–62 years). Average BMI in males was found lower (28.7) as compared with females (32).

Most common site of CSF leak was cribriform plate (n = 32, 74.4%) and Planum was found to be the least common site (n = 1, 2.3%) of CSF leak.

Intraoperatively, 23 (53.5%) patients showed high-flow leak. Intrathecal injection of fluorescein dye was used to identify the site of CSF leakage in 15 cases (34.8%). The overall success rate of primary endoscopic repair in our study was 95.3%.

Conclusion Spontaneous CSF rhinorrhea occurs secondary to elevated intracranial pressure, with a predilection for obese females in fourth to fifth decade. Individualized tailored surgical approach depending upon the site, size, and flow-variety of the defect forms the cornerstone of management.
Sinonasal Melanoma: A Single Institutional Analysis and Future Directions
Authors: Manton Taylor , Tillman Brittny , McHugh Jonathan , Bellile Emily , McLean Scott , McKean Erin
Published: December 2018

Background Sinonasal melanoma is a rare disease with a high mortality rate. The surgical management paradigm has significantly changed over the past decade with the introduction of expanded endonasal techniques. There have also been advances in management of metastatic and locally advanced disease with the advent of immunotherapy.

Methods Single-institution retrospective review of adult patients with sinonasal melanoma, surgically managed at the University of Michigan over a 9-year period. Thirty-one patients met inclusion criteria. All patients were retrospectively staged according to the 7th Edition AJCC staging system for mucosal melanoma. Parameters that may affect survival were analyzed using Cox's proportional hazard models and survival outcomes were analyzed with the Kaplan–Meier method. Additionally, a review of three patients with distant metastatic disease receiving immunotherapy is presented.

Results Most patients were managed endoscopically (67%), and had stage III disease (71%). However, 57% of stage IVB tumors were successfully managed endoscopically. Stage statistically impacted overall survival whereas distant control was impacted by stage, site of origin, mitotic rate, and necrosis. The 2-year overall survival for all stages was 77% which declined with advanced disease. Two-year locoregional control and distant control showed similar trends.

Conclusion Treatment of sinonasal melanoma has drastically changed over the past decade with increased use of expanded endonasal techniques. Our review revealed excellent 2-year overall survival in stage III disease with an appreciable decline in survival in more advanced disease. Immunotherapy may play a large role is future management given the high-risk of distant metastasis.
Simulation and optimization of a negative hydrogen Penning ion source
Authors: Rafieian Najaf Abadi M. , Mahjour-Shafiei M. , Yarmohammadi Satri M.
Published: December 2018

The results of a Particle-In-Cell Monte-Carlo Collision simulation of a cold cathode Penning type ion source are presented. The source is designed to generate H− ions through the volume production process. Twenty-one important processes including electron and heavy particle collisions are introduced into the simulation. The main focus was the energy distribution of electrons which has a large effect on the H− production rate in the volume production. The dependence of the energy distribution of electrons on the axial magnetic field was investigated. The large sensitivity of the H− production rate to the energy distribution of electrons was measured. It was observed that for an anode with a 5 mm radius increasing the axial magnetic field in the range of 0.5–1.1 T results in the increase in the H− density almost by a factor of 14. In addition, it was found that the anode with a radius of 5 mm was the most efficient anode in H− production among the anodes with radii from 3 to 6 mm.
Green’s function coupled cluster formulations utilizing extended inner excitations
Authors: Peng Bo , Kowalski Karol
Published: December 2018

In this paper, we analyze new approximations of the Green’s function coupled cluster (GFCC) method where locations of poles are improved by extending the excitation level of inner auxiliary operators. These new GFCC approximations can be categorized as the GFCC-i(n, m) method, where the excitation level of the inner auxiliary operators (m) used to describe the ionization potential and electron affinity effects in the N − 1 and N + 1 particle spaces is higher than the excitation level (n) used to correlate the ground-state coupled cluster wave function for the N-electron system. Furthermore, we reveal the so-called “n + 1” rule in this category [or the GFCC-i(n, n + 1) method], which states that in order to maintain size-extensivity of the Green’s function matrix elements, the excitation level of inner auxiliary operators Xp(ω) and Yq(ω) cannot exceed n + 1. We also discuss the role of the moments of coupled cluster equations that in a natural way assures these properties. Our implementation in the present study is focused on the first approximation in this GFCC category, i.e., the GFCC-i(2,3) method. As our first practice, we use the GFCC-i(2,3) method to compute the spectral functions for the N2 and CO molecules in the inner and outer valence regimes. In comparison with the Green’s function coupled cluster singles, doubles results, the computed spectral functions from the GFCC-i(2,3) method exhibit better agreement with the experimental results and other theoretical results, particularly in terms of providing higher resolution of satellite peaks and more accurate relative positions of these satellite peaks with respect to the main peak positions.
Decentralized control of an islanded microgrid based on offline model reference adaptive control
Authors: Sedghi Leila , Emam Masoud , Fakharian Ahmad , Savaghebi Mehdi
Published: December 2018

In this paper, offline adaptive control of a microgrid in an islanded operation mode is presented. The proposed control scheme consists of a power controller, voltage controller, and current controller, which are operating in a cascade structure. The power controller is designed based on the droop characteristics while the voltage and current loops are optimal Proportional-Integral (PI) controllers. Due to the fact that the performance of all PI controllers fundamentally depends on the proper choice of controller parameters, these parameters are optimized based on the offline utilization of the Model Reference Adaptive Control (MRAC) method and the Genetic Algorithm. The adaptation mechanism in the MRAC method is usually determined using the mathematical model of the system, while in this paper, an optimal adaptation mechanism is achieved by the Genetic Algorithm. The optimal parameters of the controller could be obtained based on the measurements of the Distributed Generation (DG) output voltage when the DG is operating with a test load without any knowledge of its model. To investigate the performance of the suggested controller, simulations are done by MATLAB/Simulink in three different scenarios including load perturbation, disconnection of a DG, and nonlinear load, where the results are compared with IEEE recommendation. In addition, the suggested controller is compared with the H2/H∞ robust controller.
Simplified gentlest ascent dynamics for saddle points in non-gradient systems
Authors: Gu Shuting , Zhou Xiang
Published: December 2018

The gentlest ascent dynamics (GAD) [W. E and X. Zhou, Nonlinearity 24, 1831 (2011)] is a time continuous dynamics to efficiently locate saddle points with a given index by coupling the position and direction variables together. These saddle points play important roles in the activated process of randomly perturbed dynamical systems. For index-1 saddle points in non-gradient systems, the GAD requires two direction variables to approximate, respectively, the eigenvectors of the Jacobian matrix and its transposed matrix. In the particular case of gradient systems, the two direction variables are equal to the single minimum mode of the Hessian matrix. In this note, we present a simplified GAD which only needs one direction variable even for non-gradient systems. This new method not only reduces the computational cost for the direction variable by half but also avoids inconvenient transpose operation of the Jacobian matrix. We prove the same convergence property for the simplified GAD as that for the original GAD. The motivation of our simplified GAD is the formal analogy with Hamilton’s equation governing the noise-induced exit dynamics. Several non-gradient examples are presented to demonstrate our method, including a two dimensional model and the Allen-Cahn equation in the presence of shear flow.
Stark effect or coverage dependence? Disentangling the EC-SEIRAS vibrational shift of sulfate on Au(111)
Authors: Pfisterer Jonas H. K. , Zhumaev Ulmas E. , Cheuquepan William , Feliu Juan M. , Domke Katrin F.
Published: December 2018

Infrared spectroscopy is a widely employed analytical tool in (electrochemical) surface science as the spectra contain a wealth of information about the interaction of interfacial adsorbates with their environment. Separating and quantifying individual contributions, for example, of co-adsorbates, the substrate or electric field effects, on the overall spectral response, however, is often non-trivial as the various interactions manifest themselves in similar spectral behavior. Here, we present an experimental approach to differentiate between and quantify potential-induced coverage dependence and field-related Stark effects observed in a sulfate band shift of 93.5 ± 1.5 cm−1/V in electrochemical infrared spectra of the showcase sulfate/Au(111) interface. In combination with a simple linear model equation used to describe the potential-induced peak shift of the sulfate stretch vibration, we determine the coverage dependence contribution to be 15.6 ± 1.2 cm−1/θSO and the Stark effect to amount to 75.6 ± 2.7 cm−1/V. Our work provides a novel route to gain fundamental insight into interfacial adsorbate interactions in electrochemical surface science.
Perspective: Uniform switching of artificial synapses for large-scale neuromorphic arrays
Authors: Tan Scott H. , Lin Peng , Yeon Hanwool , Choi Shinhyun , Park Yongmo , Kim Jeehwan
Published: December 2018

Resistive random-access memories are promising analog synaptic devices for efficient bio-inspired neuromorphic computing arrays. Here we first describe working principles for phase-change random-access memory, oxide random-access memory, and conductive-bridging random-access memory for artificial synapses. These devices could allow for dense and efficient storage of analog synapse connections between CMOS neuron circuits. We also discuss challenges and opportunities for analog synaptic devices toward the goal of realizing passive neuromorphic computing arrays. Finally, we focus on reducing spatial and temporal variations, which is critical to experimentally realize powerful and efficient neuromorphic computing systems.
A simple electrometric method for parametric determination of Jones-Wilkins-Lee equation of state from underwater explosion test
Authors: Li Kebin , Li Xiaojie , Wang Xiaohong , Yan Honghao , Yang Chenchen , Chen Xiang
Published: December 2018

The parametric determination of the Jones-Wilkins-Lee equation of state (JWL-EOS) of condensed explosives was mostly dependent on a cylinder test using a high-speed photography technique. In the present work, a simple electrometric method based on the underwater explosion test was developed with a novel pressure-conducted velocity probe permitting recording the detonation and shock wave velocity in a single test. Specifically, a velocity probe-based testing setup for the underwater explosion was designed at first to measure the oblique shock wave front of the cylinder charge. We carried out four tests using powdery cyclotrimethylenetrinitramine (RDX) and obtained the curves of detonation-shock front position versus time. The oblique shock wave fronts were then determined based on the analysis of two-dimensional steady flow, and some other parameters such as detonation pressure, adiabatic exponent, Mach number, and gas-water interface angle were calculated combining the Prandtl-Mayer expansion law. Excellent agreements with the calculation results of Kamlet’s semi-empirical formulas were achieved. By applying a numerical calculation and test-and-error process, we adjusted the six JWL-EOS parameters (A, B, C, R1, R2, and ω) constantly to make the error between numerical and experimental results of oblique shock front fall within ±2%. Finally, the JWL-EOS of powdery RDX in each test was determined, and the curves of adiabatic pressure versus relative volume were plotted as well to demonstrate the accuracy of the present method.
Live cells assessment of opto-poration by a single femtosecond temporal Airy laser pulse
Authors: Campargue G. , Zielinski B. , Courvoisier S. , Sarpe C. , Winkler T. , Sentfleben A. , Bonacina L. , Baumert T. , Wolf J. P.
Published: December 2018

We report on the first study of live cell opto-poration by single temporally shaped femtosecond laser pulses. Based on an ad hoc developed cell staining protocol, we demonstrate the influence of the pulse temporal profile on the efficiency of poration and on cell viability at four hours comparing the results obtained for four different temporal pulse shapes: positive and negative temporal Airy, positively chirped, and 30 fs bandwidth limited pulses. Each pulse has been tested on a thousand cells. The most suitable pulses for opto-poration are the positive Temporal Airy Pulses (TAP+), likely because they enhance avalanche ionization compared to bandwidth-limited shorter pulses. We discuss the results in the context of previous studies, highlighting the differences between single and multi-pulse opto-poration strategies.
Enhanced photoresponses of an optically driven VO2-based terahertz wave modulator near percolation threshold
Authors: Zhai Zhao-Hui , Zhu Hong-Fu , Shi Qiwu , Chen Si-Chao , Li Jiang , Li Ze-Ren , Schneider Harald , Zhu Li-Guo
Published: December 2018

We proposed and demonstrated a method to enhance photoresponses in the timescale from nanoseconds to microseconds of an all optically driven VO2-based terahertz (THz) wave modulator by driving the initial VO2 close to percolation threshold (via externally heating the initial VO2 thin film near insulator-to-metal transition temperature). We experimentally realized 10-fold, 3-fold, and 3-fold improvement of photosensitivity, photoresponsivity, and optical modulation bandwidth of the VO2-based THz wave modulator, respectively. Percolation theory, along with the macroscopic conductivity response, was used to explain the mechanism for photomodulation response enhancement. The enhanced photomodulation response is promising especially for optical modulators and photodetectors. This approach is also compatible with other optimization methods and can be further used to enhance other VO2-based optoelectronic devices.
Enhanced photoluminescence and directional white-light generation by plasmonic array
Authors: Kamakura Ryosuke , Murai Shunsuke , Yokobayashi Yusuke , Takashima Keijiro , Kuramoto Masaru , Fujita Koji , Tanaka Katsuhisa
Published: December 2018

White light-emitting diodes (LEDs), light sources that combine blue LEDs and yellow phosphors, are equipped with bulky optics such as lenses, mirrors, and/or reflectors to shape the light into the required directions. The presence of bulky optics causes optical loss and limits the design. Here, a periodic array of metallic nanocylinders, which exhibits a high scattering efficiency owing to the excitation of localized surface plasmon resonance, is proposed as an alternative means of achieving a directional output without the limitations of bulky optics. A prototype of a directional light emitter is fabricated consisting of an Al nanocylinder array on a yellow phosphor plate and a blue laser. The array shapes the yellow luminescence into the forward direction and generates directional quasi-white light (correlated color temperature of 4900 K). The intensity enhancement reaches a factor of five in the forward direction and is further improved up to a factor of seven by the deposition of a multilayer dichroic mirror on the back side of the phosphor plate, resulting in conversion efficiencies as high as 90 lm/W. Our results pave the way toward the development of efficient and compact directional white-light-source devices without any bulky optics.
A tunable path-separated electron interferometer with an amplitude-dividing grating beamsplitter
Authors: Yasin Fehmi S. , Harada Ken , Shindo Daisuke , Shinada Hiroyuki , McMorran Benjamin J. , Tanigaki Toshiaki
Published: December 2018

We demonstrate a tunable path-separated electron interferometer using a single amplitude-dividing beamsplitter to prepare multiple spatially isolated, coherent electron probe beams. We place four electrostatic bi-prisms in the optical column of a scanning transmission electron microscope (STEM) to achieve path separations of up to 25 μm, the largest demonstrated within amplitude-division electron interferometers while maintaining fringe visibility of the directly observed interference fringes at the detector. We characterize the fringe visibility of this setup over a range of path separations and perform STEM holography to reconstruct the full object wave of a fabricated Si ramp test phase object. We report a quantitative object-wave measurement in this configuration and confirm with an independent off-axis electron holography measurement. This experimental design can potentially be applied to high-resolution phase imaging and fundamental physics experiments, such as an exploration of the electron wave packet coherence length and the Aharonov-Bohm effect.
Quasi-adiabatic path integral approach for quantum systems under the influence of multiple non-commuting fluctuations
Authors: Palm T. , Nalbach P.
Published: December 2018

Quantum systems are typically subject to various environmental noise sources. Treating these environmental disturbances with a system-bath approach beyond weak coupling, one must refer to numerical methods as, for example, the numerically exact quasi-adiabatic path integral approach. This approach, however, cannot treat baths which couple to the system via operators, which do not commute. We extend the quasi-adiabatic path integral approach by determining the time discrete influence functional for such non-commuting fluctuations and by modifying the propagation scheme accordingly. We test the extended quasi-adiabatic path integral approach by determining the time evolution of a quantum two-level system coupled to two independent baths via non-commuting operators. We show that the convergent results can be obtained and agreement with the analytical weak coupling results is achieved in the respective limits.
Observation of additional delayed-time in chaos synchronization of uni-directionally coupled VCSELs
Authors: Jayaprasath Elumalai , Wu Zheng-Mao , Sivaprakasam Sivaraman , Xia Guang-Qiong
Published: December 2018

We report an experimental and numerical investigation on the existence of additional delayed-time in chaos synchronization of two uni-directionally coupled vertical-cavity surface-emitting lasers (VCSELs) for the first time. Under a generalized synchronization scenario, we demonstrate that there exists an additional delayed-time in addition to the time-of-flight between the two coupled VCSELs. The cross-correlation function analysis has been used as a method to determine the coupling delay and synchronization quality between two uni-directionally coupled chaotic VCSELs. We show that the injection strength significantly influences the additional delayed-time, and the injection strength analysis eventually substantiates the existence of additional delayed-time between the coupled lasers in experiments. The experimental results are in accordance with the numerical results. Additionally, we numerically study the effect of laser’s internal parameter mismatches on additional delayed-time and synchronization quality between the lasers.
Quantum mechanical study of the 16O + 18O18O → 16O18O + 18O exchange reaction: Integral cross sections and rate constants
Authors: Honvault P. , Guillon G. , Kochanov R. , Tyuterev V.
Published: December 2018

The isotopic exchange reaction, 16O + 18O18O → 16O18O + 18O, involving excited ozone, O3*, as intermediate complex, was investigated by means of a time independent quantum mechanical approach using the TKTHS potential energy surface (PES) [V. G. Tyuterev et al., J. Chem. Phys. 139, 134307 (2013)] of ozone. State-to-state integral cross sections were calculated for collision energies lower than 0.4 eV. Then specific and thermal rate constants were computed between 10 K and 350 K using these cross sections. The full quantum thermal rate constant is found to be in better agreement with the most recent experimental data than with previous studies where other O3 PESs were employed, confirming therefore the higher accuracy of the TKTHS PES. However, the present theoretical thermal rate constant still remains below the measured rate, maybe due to the neglect of non-adiabtic couplings.
Controlling epidemic outbreak based on local dynamic infectiousness on complex networks
Authors: Chen Xiao-Long , Cai Shi-Min , Tang Ming , Wang Wei , Zhou Tao , Hui Pak-Ming
Published: December 2018

Resources are limited in epidemic containment; how to optimally allocate the limited resources in suppressing the epidemic spreading has been a challenging problem. To find an effective resource allocation strategy, we take the infectiousness of each infected node into consideration. By studying the interplay between the resource allocation and epidemic spreading, we find that the spreading dynamics of epidemic is affected by the preferential resource allocation. There are double phase transitions of the fraction of infected nodes, which are different from the classical epidemic model. More importantly, we find that the preferential resource allocation has double-edged sword effects on the disease spreading. When there is a small transmission rate, the infected fraction at the steady state decreases with the increment of degree of resource allocation preference, which indicates that resources of the healthy nodes should be allocated preferentially to the high infectious nodes to constrain the disease spreading. Moreover, when there is a large transmission rate, the fraction of infected nodes at the steady state increases with the increment of the degree of the preference, but the resource allocation is determined by the stage of epidemic spreading. Namely, in the early stage of the disease spreading, resources should be allocated preferentially to the high infectious nodes similar to the case of a small transmission rate. While after the early stage, resources should be allocated to the low infectious nodes. Based on the findings, we propose a simple resource allocation strategy that can adaptively change with the current fraction of infected nodes and the disease can be suppressed to the most extent under the proposed strategy.
Almost compact moving breathers with fine-tuned discrete time quantum walks
Authors: Vakulchyk I. , Fistul M. V. , Zolotaryuk Y. , Flach S.
Published: December 2018

Discrete time quantum walks are unitary maps defined on the Hilbert space of coupled two-level systems. We study the dynamics of excitations in a nonlinear discrete time quantum walk, whose fine-tuned linear counterpart has a flat band structure. The linear counterpart is, therefore, lacking transport, with exact solutions being compactly localized. A solitary entity of the nonlinear walk moving at velocity v would, therefore, not suffer from resonances with small amplitude plane waves with identical phase velocity, due to the absence of the latter. That solitary excitation would also have to be localized stronger than exponential, due to the absence of a linear dispersion. We report on the existence of a set of stationary and moving breathers with almost compact superexponential spatial tails. At the limit of the largest velocity v=1, the moving breather turns into a completely compact bullet.
Electrostatic rogue waves in double pair plasmas
Authors: Ahmed N. , Mannan A. , Chowdhury N. A. , Mamun A. A.
Published: December 2018

A nonlinear Schrödinger equation is derived to investigate the modulational instability of ion-acoustic (IA) waves (IAWs) in a double pair plasma system containing adiabatic positive and negative ion fluids along with super-thermal electrons and positrons. The analytical analysis predicts two types of modes, viz., fast (ωf) and slow (ωs) IA modes. The possible stable and unstable parametric regions for the IAWs in the presence of external perturbation can be observed for both ωf and ωs. The number density of the negative ions and positrons plays a vital role in generating the IA rogue waves in the modulationally unstable region. The applications of our present work in astrophysical environments [viz., D-region (H+, O2−) and F-region (H+, H−) of the Earth’s ionosphere] and in laboratory plasmas [viz., pair-ion fullerene (C+, C−)] are pinpointed.
Thermoelectric-cooled liquid bath chiller capable of unattended operation at −28 °C
Authors: Lunceford Chad , Drucker Jeff
Published: December 2018

Using thermoelectric elements, we have developed a simple liquid bath chiller that is inexpensive and easy to fabricate. Typically, small experimental apparatus can be cooled using a liquid cold bath. These cold baths require continuous addition of a coolant such as dry ice or liquid N2 to maintain the desired temperature, which becomes tedious during long experiments. We demonstrate the capability of our liquid bath chiller to stably maintain a bath temperature of −28 °C for days at a time, without the need of continuous monitoring. We explore the effects of thermoelectric element capacity and configuration in addition to the temperature, composition, and flow rate of the liquid flowing through the liquid heat exchanger that transports heat away from the thermoelectric element.