bluuebunny/crossref_metadata_2025 huggingface dataset:
Application Analysis of AD8479 in the Acquisition Unit of Electronic Current Transformer
Authors: Liu Xi , Yang Jianhua , Qian Bifu , Zhang Lei
Published: April 2018

Electronic current transformer acquisition unit was installed outdoors and near the circuit breaker. The poor environments, including high common mode voltage, electromagnetic interference and other factors were a serious of disadvantages impacts on the acquisition unit. The paper introduced the parameter characteristics and functions of Rogowski coil, the differential amplifier chip AD8479, and filter circuit in detail. The application circuit was designed based on proper parameters. Lastly, the interference was inhibited effectively, and the electronic current transformer acquisition unit run more reliably resulted from theoretical analysis and field test.
Prescribed Performance Control for Two-axis Optronic Stabilized Platform
Authors: Yexing Wang , Changxin Luo , Tao Zhang , Yaning Liu , Chuhan Xiao
Published: April 2018

Aiming at improving the tracking and stabilizing performance of two-axis optronic stabilized platform with Stribeck friction and uncertain velocity disturbance, a prescribed performance control strategy with unknown initial errors is designed. By designing a new performance function, the limit of traditional prescribed control that the initial error has to be known accurately is broken through. The strategy possesses strong robustness against unknown disturbance, and the state error is restrained to a predefined arbitrary small residual. It is guaranteed that the closed-loop system is uniformly ultimately bounded. The simulation results demonstrate the effectiveness of proposed strategy.
Research on grounding grid corrosion classification method based on convolutional neural network
Authors: Du Jingyi , Yan Liqian , Wang Haixia , Huang Qiong
Published: April 2018

Aiming at the problem that the traditional detection methods can not accurately classify the corrosion degree of grounding grids. The corrosion image is taken as the research object, the convolution neural network is used as the algorithm firstly to classify the corrosion degree. Firstly, the corrosion simulation experiment was carried out, and the sample library was established by using the corrosion image collected in different stages. Then, according to the LeNet-5 model, the traditional CNN and improved CNN models were designed for corrosion classification of grounding grid. Simulation experiments were carried out in the preprocessed samples. Finally, the experimental results of Soft-max and SVM classifier are compared and analyzed. The results show: the classification results of the two models were better than those of the original samples, and the classification performance of SVM is better than that of Soft-max. The improved model can improve classification accuracy. This study fills the blank of detecting the corrosion degree of grounding grid by image method, and it is significant to quickly grasp the corrosion degree to avoid faults or accidents.
Research on Speed Sensorless Vector Control System of Asynchronous Motor Based on MRAS
Authors: Liao Zili , Zhao Qijin , Zhang Xinxi , Chen Luming
Published: April 2018

This paper analysed the basic principle of speed sensorless vector control system. Based on speed and current closed loop vector control, combined with a simple and feasible current hysteresis control strategy, the whole speed sensorless system of asynchronous motor is simulated in MATLAB/Simulink. The method uses the Model Reference Adaptive System (MRAS). The observation and analysis of waveform shows that the system has good static performance and robustness. The control effects are also as similar as the vector control system which contains speed sensor.
The Electric Vehicle Time-of-Use Price Optimization Model Considering the Demand Response
Authors: Shi Zejing , Zhu Ninghui , Yu Jinsong
Published: April 2018

A large number of electric vehicles connecting to the distribution grids usually introduce significant fluctuations to the grid and the loads. To solve the problem, guiding the users coordinated charging is proposed. Firstly, the uncontrolled charging power prediction models of electric vehicles are established, and the Monte Carlo method is adopted to simulate the power demands of different electric vehicles, and the influences on the load peak-valley ratios and the voltages and losses of the grid are all analyzed. Then the vehicle responses model considering the time-of-use price is analyzed, and the vehicle response ratios are obtained under different time-of-use prices. Finally the multi-objective optimization model is constructed including the minimum peak-valley ratio, maximum consumption satisfaction index and cost satisfaction index. In the procedure, vehicles and the grid are both taken into account. The results indicate the proposed method could guide the users coordinated charging, and the peak shaving and valley filling is also achieved, and the operation of the distribution grid is improved.
Designing and Modeling of Automated Anti-theft Electricity Distribution System
Authors: Khan Awais , Xie Wei , Aftab Qureshi Suhail , Ilyas Muhammad , Lin JingChun , Liu Guidong
Published: April 2018

In this modern era electricity is the major component of human life. Its play a vital role to facilitate the human life by operating all modern electrical equipment. The consumption of electricity increases rapidly due to its uses in the domestic and industrial sector. In the distribution of electricity, there are few emerging issues leads to huge losses. The illegal connection of electricity in remote areas increases rapidly. Such theft of electricity from distribution line leads to huge losses in revenue of electricity. Pakistan facing huge energy crisis due to a shortage of electricity generation. This research project modeled and the designed the hardware prototype of automated anti-theft electricity distribution system. The proposed system detects the illegal load and burns it by sending high voltage signal from capacitor bank. The legal load is made safe and uninterrupted during execution of illegal load.
A dynamic model of battery energy storage system based on the external characteristic equivalent
Authors: Qu Xing , Li Xinran
Published: April 2018

With the increasing application of battery energy storage in the power grid, there will be inevitably a large number of battery energy storage systems (BESS) in the future distribution network. It is very important to study the equivalent model of BESS which is suitable for comprehensive load modelling. In this paper, the battery group is established based on a type of general battery model, and then, a simulation platform of BESS based on MATLAB/Simulink is constructed, using a double closed loop control strategy with constant power as control object. Through the simulation analysis of grid-connected characteristics of BESS, a semi-mechanism dynamic model of BESS based on the external characteristic equivalent is proposed. This model represents the variation trend of the electrical variables of BESS during transient state, and considers the inertia characteristics of the BESS relative to power grid. By comparing the simulation results under different disturbance intensity, the proposed model can describe the transient characteristics of BESS, and can meet the performance requirements of the load modelling for the distribution network side.
Substitution of Acetylene Black by Using Modified Flake Graphite Applied in Activated Carbon Supercapacitors
Authors: Zhao Peng , He Chunmei , Hu Wencheng
Published: April 2018

Flake graphite was mechanically modified at different times in N-methyl pyrrolidone under normal pressure. The results of the scanning electron microscopy, X-ray diffraction, and transmission electron microscopy suggested that the structure of the flake graphite was modified. The crystallinity of the flake graphite, and many defects were introduced into the material. The evaluation of capacitor performance by cyclic voltammetry, galvanostatic charge/discharge tests, and electrochemical impedance spectroscopy was also performed. Results showed that the electrochemical performance of flake graphite was strongly enhanced, particularly when it was exfoliated for 6 h. Moreover, the electrochemical capacitive properties of activated carbon were obviously enhanced through the substitution of acetylene black by flake graphite modified for 6 h.
Electrochemical Anti-corrosion System of Iron Tower Based on Solar Power Supply
Authors: Tian Tian , Xiao Shiwu
Published: April 2018

Aiming at the serious problem of the corrosion of the transmission tower in the coastal area or in the harsh industrial area, a kind of electro-chemical anti-corrosion system based on solar power is designed. The system consists of a solar power module and an electrochemical anti-corrosion module: The solar power module consists of a solar panel, a photovoltaic controller, a accumulator and a constant potentiometer. The Electrochemical anti-corrosion modules include an anode block and an anode bed and reference electrode. The photovoltaic energy technology and forced current cathodic protection technology are used in the system, to achieve the effective protection of the tower anti-corrosion. Solar power supply to the nearest, solve the long-distance transmission loss and the high installation costs, form a simple structure, stable operation, low cost, clean and environmental protection, long service life of anti-corrosion system, with good economic efficiency and social benefits. It is of great significance to ensure the safe operation of the tower, maintain the normal operation of the power grid, and even promotes the optimization and upgrading of the industrial structure, save energy and reduces emissions, improve the safe and stable operation of the power system and the economic benefits, etc.
Application of Component Technology in Power Simulation Training
Authors: Zhao Xi-Lan , Wang Geng , Yang Jian-mei , Gao Feng
Published: April 2018

With the rapid development of power grid and the implementation of integrated management and control mode, the knowledge, technology and skills of power supply production management personnel have put forward higher requirements, and the establishment of simulation system for the integration of power grid regulation and control is to improve the relevant professionals Quality and skill level of the important means, component-based modeling method can quickly establish the entire power grid of the secondary model, is gradually becoming a new trend in the field of power simulation. The research results of this paper have been successfully applied in the power grid of Gansu Province, with cost-effective, more complete and more realistic simulation, and got good training effect.
A simulation training evaluation method for distribution network fault based on radar chart
Authors: Yuhang Xu , Tongning Li , Yili Wang , Yibin Lin , Kuntu Wei , Wei Zhang
Published: April 2018

In order to solve the problem of automatic evaluation of dispatcher fault simulation training in distribution network, a simulation training evaluation method based on radar chart for distribution network fault is proposed. The fault handling information matrix is established to record the dispatcher fault handling operation sequence and operation information. The four situations of the dispatcher fault isolation operation are analyzed. The fault handling anti-misoperation rule set is established to describe the rules prohibiting dispatcher operation. Based on the idea of artificial intelligence reasoning, the feasibility of dispatcher fault handling is described by the feasibility index. The relevant factors and evaluation methods are discussed from the three aspects of the fault handling result feasibility, the anti-misoperation correctness and the operation process conciseness. The detailed calculation formula is given. Combining the independence and correlation between the three evaluation angles, a comprehensive evaluation method of distribution network fault simulation training based on radar chart is proposed. The method can comprehensively reflect the fault handling process of dispatchers, and comprehensively evaluate the fault handling process from various angles, which has good practical value.
Causal Analysis to a Subway Accident: A Comparison of STAMP and RAIB
Authors: Zhou Yao , Yan Fei
Published: April 2018

Accident investigation and analysis after the accident, vital to prevent the occurrence of similar accident and improve the safety of the system. Different methods led to a different understanding of the accident. In this paper, a subway accident was analysed with a systemic accident analysis model – STAMP (System-Theoretic Accident Modelling and Processes). The hierarchical safety control structure was obtained, and the system-level safety constraints were obtained, controllers of the physical layer were analysed one by one, and put forward the relevant safety requirements and constraints, the dynamic analysis of the structure of the safety control is carried out, and the targeted recommendations are pointed out. In comparison with the analysis results obtained by the Rail Accident Investigation Branch (RAIB). Some useful findings have been concluded. STAMP treats safety as a control problem and reduces or eliminates causes of the accident from the controlling perspective. Whereas RAIB obtains causes of the accident by analysing the sequence of events related to the accident and reasons of these events, then chooses one(or more)event(s) as the immediate cause and some of the key events as causal factors. RAIB analysis is based on the sequential event models, but STAMP analysis provides us with a holistic, dynamic way to control system to maintain safety.
Control and Simulation of Torque Converter Lock-up Clutch
Authors: Zhao Li-mei , Wu Huai-chao , Peng Zheng-hu , Zhang Cheng , Tang Shi-hao , Long Yun-xiang , Li Guo-qiao
Published: April 2018

Considering the requirements of dynamic performance and quality during the torque converter locking process, a two parameters latch-up control strategy was designed, and a simulation method to study the control performance by use of processor in loop (PIL) simulation technology was proposed. Through the study of the practically applied requirements of a loader, a two parameter lock-up control strategy with turbine speed signal and gear signal as main control parameters was developed. According to the control strategy, the logic diagram of real-time locking and unlocking control of the latch-up clutch was established by using Matlab/Simulink. Then, PIL technology was used to realize the co-simulation of CCS and Simulink. Simulation results show that the latch-up control model is correct and the lock-up clutch can effectively lock and unlock in accordance with the lock-uprule.
Reconfigurable Fault Tolerant Control for Spacecraft Based on Modified IMM Algorithm
Authors: Xiaoyun Li , Wei Du
Published: April 2018

This paper proposes an integrated fault detection, diagnosis, and reconfigurable control method for attitude tracking of a spacecraft. A novel IMM algorithm, based on the unscented Kalman filter and an index related to the closed-loop system performance, is presented to detect and diagnose the faults. To achieve steady attitude tracking, the sliding mode variable structure controller is designed. When a fault is detected and isolated, the controller structure is reconfigured to compensate the faulty system to maintain the system performance. A simulation example evaluating the attitude tracking process is employed, which demonstrates the efficiency of the proposed approach.
Research and Implementation of Robot Path Planning Based onVSLAM
Authors: Wang Zi-Qiang , Xu He-Gen , Wan You-Wen
Published: April 2018

In order to solve the problem of warehouse logistics robots planpath in different scenes, this paper proposes a method based on visual simultaneous localization and mapping (VSLAM) to build grid map of different scenes and use A* algorithm to plan path on the grid map. Firstly, we use VSLAMto reconstruct the environment in three-dimensionally. Secondly, based on the three-dimensional environment data, we calculate the accessibility of each grid to prepare occupied grid map (OGM) for terrain description. Rely on the terrain information, we use the A* algorithm to solve path planning problem. We also optimize the A* algorithm and improve algorithm efficiency. Lastly, we verify the effectiveness and reliability of the proposed method by simulation and experimental results.
Design and Implementation of Fire Extinguisher Robot with Robotic Arm
Authors: Memon Abdul Waris , Du Juan , Abro Abdul Haleem , Shah Sharmeen Iftikhar , Bhutto Moazzam Ali
Published: April 2018

Robot is a device, which performs human task or behave like a human-being. It needs expertise skills and complex programming to design. For designing a fire fighter robot, many sensors and motors were used. User firstly send robot to an affected area, to get live image of the field with the help of mobile camera via Wi-Fi using IP camera application to laptop. If any signs of fire shown in image, user direct robot in that particular direction for confirmation. Fire sensor and temperature sensor detects and measures the reading, after confirmation robot sprinkle water on affected field. During extinguish process if any obstacle comes in between the prototype and the affected area the ultrasonic sensor detects the obstacle, in response the robotic arm moves to pick and place that obstacle to another location for clearing the path. Meanwhile if any poisonous gas is present, the gas sensor detects and indicates by making alarm.
A Micro SLAM System Based on ORB for RGB-D Cameras
Authors: Wang Fei , Ruan Xiaogang , Dong Pengfei , SIE OUATTARA
Published: April 2018

In this paper, a micro SLAM system based on ORB features for RGB-D cameras has been proposed. With only a RGB-D sensor, this method can be applied in small environment for localization and mapping. Furthermore, the task of 3D reconstruction can also be accomplished by using the approach. The pose graph based on Bundle Adjustment is adopted for reducing the estimation error. In order to further speed up computing to meet the requirement of real-time, we have proposed the piecewise optimization strategy. The approach is evaluated on public benchmark datasets. Compared with several state-of-the-art scheme, this method has proven to work well in these environments.
The Optimal Degree of Gravity Spherical Harmonic Model Calculation for Gravity Disturbance Compensation in Inertial Navigation
Authors: TIE Junbo , WU Meiping , Cao Juliang , Lian Junxiang , Cai Shaokun , Wang Lin
Published: April 2018

In recent years, the significant improvement of inertial navigation, leaves the gravity disturbance as the important factor which affects the accuracy of inertial navigation. This paper focus on the compensation for gravity disturbance with gravity spherical harmonic model, especially the optimal degree of gravity spherical harmonic model with which to calculate the gravity disturbance. The effect of gravity disturbance on inertial navigation is analysed based on the amplitude-frequency response characteristics of inertial navigation error differential equation, then the dominantly influential frequency band of gravity disturbance can be found which is the target of compensation. Combination the dominantly influential frequency band with the spatial resolution of the Earth’s gravity spherical harmonic model EGM2008 which is used to calculate the gravity disturbance, the optimal degree can be determined based on an algorithm proposed in this paper. Finally, shipborne inertial navigation experiment confirms the correctness and effectiveness of the proposed algorithm.
Osteosarcoma: a comprehensive review
Authors: Misaghi Amirhossein , Goldin Amanda , Awad Moayd , Kulidjian Anna A
Published: April 2018

Osteosarcoma (OS) is a relatively rare tumor of bone with a worldwide incidence of 3.4 cases per million people per year. For most of the twentieth century, five-year survival rates for classic OS were very low. In the 1970s, the introduction of adjuvant chemotherapy in the treatment of OS increased survival rates dramatically. The current article reviews the various types of OS and analyzes the clinical and histological features. We also examine historical and current literature to present a succinct review of methods for diagnosis and staging, as well as treatment, and we also discuss some of the future directions of treatment.
Clinical Pharmacology Considerations for Development of β Lactamase Inhibitor Combination with Antibiotics
Authors: Srinivas Nuggehally
Published: April 2018

The shrinking drug pipeline for antibacterial drugs has made it very precious to discover and develop novel drugs in this space. In this context, the recent approvals of β lactamase inhibitors with either cephalosporin or penem as combination drugs are welcome news to the community. There are number of β lactamase inhibitors with suggested partnered drugs that are currently in various stages of drug development. The focus of this manuscript is to provide some perspectives on clinical pharmacology considerations that may aid in the successful development of such combination drugs. In this regard, a broad framework which includes pharmacokinetics (PK), pharmacodynamics (PD) and PK/PD guided surrogate strategies are provided to enable an informed dosing decision of the combination agent.
Water-Promoted Chlorination of 2-Mercaptobenzothiazoles
Authors: Wimmer Laurin , Parmentier Michael , Riss Bernard , Kapferer Tobias , Ye Chao , Li Lei , Kim Hongyong , Li Jialiang
Published: April 2018

Substituted benzothiazoles play an important role in medicinal chemistry due to their pharmacological properties. Their 2-substituted derivatives are often prepared from 2-chlorobenzothiazoles, which in turn can be synthesized from the 2-mercapto precursor using sulfuryl chloride. In practice, this seemingly straightforward and widely used reaction can be impeded by poor reproducibility and low reaction yields. In this communication, we report that the simple addition of water to the reaction leads to remarkable improvements in reaction efficiency. We attribute this effect to the formation of acid through partial hydrolysis of sulfuryl chloride. This hypothesis is supported by the observation that improved yields were also obtained in the presence of some anhydrous acidic additives. The simple combination of sulfuryl chloride and water reproducibly provides excellent yields for a range of chlorinated products.
Controlled Aerobic Oxidation of Primary Benzylic Alcohols to
Aldehydes Catalyzed by Polymer-Supported Triazine-Based
Dendrimer–Copper Composites
Authors: Pan Shiguang , Yan Shuo , Osako Takao , Uozumi Yasuhiro
Published: April 2018

A controlled aerobic oxidation of primary benzylic alcohols to the corresponding benzaldehydes by using polystyrene–poly­(ethylene glycol) (PS–PEG) resin-supported triazine-based polyethyleneamine dendrimer–copper complexes [PS–PEG-TD2–Cu(II)] was developed. In particular, PS–PEG-TD2–Cu(OAc)2 efficiently catalyzed the aerobic oxidation of benzylic alcohols in the presence of a catalytic amount of TEMPO under atmospheric conditions to give the corresponding aldehydes in up to quantitative yield. The catalyst was readily recovered by simple filtration and reused four times without significant loss of its catalytic activity.
Diagnosis and Staging of Lymphedema
Authors: Goss Jeremy , Greene Arin
Published: April 2018

Lymphedema often is confused with other causes of extremity edema and enlargement. Understanding the risk factors and physical examination signs of lymphedema can enable the health care practitioner to accurately diagnose patients ∼90% of the time. Confirmatory diagnosis of the disease is made using lymphoscintigraphy. It is important to correctly diagnose patients with lymphedema so that they can be managed appropriately.
Nonoperative Treatment of Lymphedema
Authors: Moeller Julie , Cleveland Sarah , Schaverien Mark
Published: April 2018

Complex decongestive therapy is the mainstay of lymphedema (LE) therapy. It consists of two phases: an intensive volume reduction phase, principally involving low-stretch bandages and manual lymph drainage (MLD), followed by compression garment use to maintain the reduction achieved. Adjunctive treatments include the use of a sequential gradient pump, LE-specific exercises, skin and nail care, as well as risk-reduction precautions. Herein the techniques are described and the evidence for their effectiveness is reviewed.
Effect of Orbicularis Muscle Resection during Blepharoplasty on the Position of the Eyebrow
Authors: Patrocinio Lucas , Patrocinio Jose , Patrocinio Tomas
Published: April 2018

Dermatochalasis is a skin excess in the upper eyelid which may be associated with either an aesthetic and functional defect, blocking the peripheral vision. Upper blepharoplasty is the gold standard procedure for correction of dermatochalasis and to restore youthful contours to the periorbita. It is one of the most commonly performed procedures in aesthetic plastic surgery; however, there is still a lack of consensus about this procedure. The excess skin is sometimes removed alone or in conjunction with a strip of orbicularis oculi muscle. The rationale for both muscle and skin resection or skin alone preserving the muscle is uncertain. Some authors have studied the aging influence in brow position, and a few studies pointed out the influence of the upper blepharoplasty on brow height. The true effects, regarding the position of the eyebrow, of both techniques, with or without resection of the preseptal orbicularis oculi muscle, are unclear. The authors present a review of the literature to find the rationale for resecting or preserving the orbicularis oculi muscle in upper eyelid blepharoplasty and its relation to eyebrow position.
The Open Browlift
Authors: Connell Bruce , Sundine Michael
Published: April 2018

The eyes and periorbital areas are critical components for the harmonious treatment of the aging face. The authors prefer the open browlift for rejuvenation of the forehead area. The open browlift is the most versatile, effective, and long-lasting method for the treatment of the forehead. The analysis of the forehead area, alternative treatments, variations in incisions, and key components of the surgical procedure are to be reviewed.
Epileptic Encephalopathy in Adams–Oliver Syndrome Associated to a New DOCK6 Mutation: A Peculiar Behavioral Phenotype
Authors: Pisciotta Livia , Capra Valeria , Accogli Andrea , Giacomini Thea , Prato Giulia , Tavares Purificação , Pinto-Basto Jorge , Morana Giovanni , Mancardi Maria
Published: April 2018

Adams–Oliver syndrome (AOS) is characterized by a combination of congenital scalp defects (aplasia cutis congenita) and terminal transverse limb malformations of variable severity. When neurological findings are present, patients are reported as AOS variants. We describe a child with compound heterozygosity of the DOCK6 gene, aplasia cutis, terminal transverse limb defects, cardiovascular impairment, intellectual disability, and brain malformations with intracranial calcifications. He suffers from a severe refractory epileptic encephalopathy characterized by polymorphic seizures with prolonged periods of electroencephalogram (EEG), continuous epileptiform activity related to clinical inactivity, and closure of eyes with an “ON-OFF” behavior.
Kinetic effects on the morphology and stability of the pressure-induced extended-solid of carbon monoxide
Authors: Dang Nhan C. , Ciezak-Jenkins Jennifer A.
Published: April 2018

In this work, the dependence of the morphology and stability of the extended solid of carbon monoxide (CO) is correlated to the rate of transformation from the molecular CO to extended solid of CO using optical imaging, photoluminescence, Raman spectroscopy, and X-ray diffraction. The analyses show the rate and pressure of the transformation to be strongly controlled by catalytic effects, both chemical and optical. In a larger volume per reaction area, the transformation was found to require either a longer time at an elevated pressure or a higher pressure compared to a sample synthesized in a smaller volume per reaction area, leading to the conclusion that the transformation rate is slower for a sample in a larger volume per reaction area. A faster rate of transformation was also noted when the reaction area of a CO sample was catalyzed with H2SO4. Through variation of the volume per reaction area, pressure or the addition of catalysts, it was possible to control the rate of the phase transition and therefore the morphology. In general, the extended solid of CO synthesized with a faster rate showed a more ordered structure and increased metastability relative to the material formed with a slower compression rate.
Chimera states in brain networks: Empirical neural vs. modular fractal connectivity
Authors: Chouzouris Teresa , Omelchenko Iryna , Zakharova Anna , Hlinka Jaroslav , Jiruska Premysl , Schöll Eckehard
Published: April 2018

Complex spatiotemporal patterns, called chimera states, consist of coexisting coherent and incoherent domains and can be observed in networks of coupled oscillators. The interplay of synchrony and asynchrony in complex brain networks is an important aspect in studies of both the brain function and disease. We analyse the collective dynamics of FitzHugh-Nagumo neurons in complex networks motivated by its potential application to epileptology and epilepsy surgery. We compare two topologies: an empirical structural neural connectivity derived from diffusion-weighted magnetic resonance imaging and a mathematically constructed network with modular fractal connectivity. We analyse the properties of chimeras and partially synchronized states and obtain regions of their stability in the parameter planes. Furthermore, we qualitatively simulate the dynamics of epileptic seizures and study the influence of the removal of nodes on the network synchronizability, which can be useful for applications to epileptic surgery.
Reversible magnetic logic gates based on spin wave interference
Authors: Balynskiy Michael , Chiang Howard , Gutierrez David , Kozhevnikov Alexander , Filimonov Yuriy , Khitun Alexander
Published: April 2018

We propose and develop reversible magnetic logic gates based on spin wave interference. The gates consist of passive elements including spin waveguides, cross-junctions, and phase shifters. Logic 0 and 1 are encoded in the phase of the propagating spin wave (0 or π). There are different possible input-output trajectories for the propagating spin waves, where some of the trajectories contain phase shifters and others do not. In each case, the particular input-output trajectory and the resultant output phase depend on the input phase combination. The redirection takes place in the cross junctions. Two waves coming to a junction in-phase propagate through the junction without reflection. In contrast, two waves coming to a junction out-of-phase are completely reflected back. The process of redirection is illustrated by numerical modeling of a nanometer-scale junction comprising two chains of spins, which operates at zero temperature. We also present experimental data on spin wave redirection in a micrometer-size cross junction made of Y3Fe2(FeO4)3 operating at room temperature. Our results demonstrate a prominent spin wave redirection, where the ratio of the transmitted power between the in-phase and out-of-phase cases exceeds 45 dB at room temperature. Based on these experimental data, we estimate the energy per operation in spin wave reversible logic circuits. The proposed reversible gates may provide a route to magnetic logic circuitry with power dissipation less than kT per operation.
A comparative computational study of coarse-grained and all-atom water models in shock Hugoniot states
Authors: Min Sa Hoon , Berkowitz Max L.
Published: April 2018

We performed molecular dynamics simulations to study how well some of the water models used in simulations describe shocked states. Water in our simulations was described using three different models. One was an often-used all-atom TIP4P/2005 model, while the other two were coarse-grained models used with the MARTINI force field: non-polarizable and polarizable MARTINI water. The all-atom model provided results in good agreement with Hugoniot curves (for data on pressure versus specific volume or, equivalently, on shock wave velocity versus “piston” velocity) describing shocked states in the whole range of pressures (up to 11 GPa) under study. If simulations of shocked states of water using coarse-grained models were performed for short time periods, we observed that data obtained for shocked states at low pressure were fairly accurate compared to experimental Hugoniot curves. Polarizable MARTINI water still provided a good description of Hugoniot curves for pressures up to 11 GPa, while the results for the non-polarizable MARTINI water substantially deviated from the Hugoniot curves. We also calculated the temperature of the Hugoniot states and observed that for TIP4P/2005 water, they were consistent with those from theoretical calculations, while both coarse-grained models predicted much higher temperatures. These high temperatures for MARTINI water can be explained by the loss of degrees of freedom due to coarse-graining procedure.
Sheet, ligament and droplet formation in swirling primary atomization
Authors: Shao Changxiao , Luo Kun , Chai Min , Fan Jianren
Published: April 2018

We report direct numerical simulations of swirling liquid atomization to understand the physical mechanism underlying the sheet breakup of a non-turbulent liquid swirling jet which lacks in-depth investigation. The volume-of-fluid (VOF) method coupled with adapted mesh refinement (AMR) technique in GERRIS code is employed in the present simulation. The mechanisms of sheet, ligament and droplet formation are investigated. It is observed that the olive-shape sheet structure is similar to the experimental result qualitatively. The numerical results show that surface tension, pressure difference and swirling effect contribute to the contraction and extension of liquid sheet. The ligament formation is partially at the sheet rim or attributed to the extension of liquid hole. Especially, the movement of hairpin vortex exerts by an anti-radial direction force to the sheet surface and leads to the sheet thinness. In addition, droplet formation is attributed to breakup of ligament and central sheet.
Performance of exchange-correlation functionals in density functional theory calculations for liquid metal: A benchmark test for sodium
Authors: Han Jeong-Hwan , Oda Takuji
Published: April 2018

The performance of exchange-correlation functionals in density-functional theory (DFT) calculations for liquid metal has not been sufficiently examined. In the present study, benchmark tests of Perdew-Burke-Ernzerhof (PBE), Armiento-Mattsson 2005 (AM05), PBE re-parameterized for solids, and local density approximation (LDA) functionals are conducted for liquid sodium. The pair correlation function, equilibrium atomic volume, bulk modulus, and relative enthalpy are evaluated at 600 K and 1000 K. Compared with the available experimental data, the errors range from −11.2% to 0.0% for the atomic volume, from −5.2% to 22.0% for the bulk modulus, and from −3.5% to 2.5% for the relative enthalpy depending on the DFT functional. The generalized gradient approximation functionals are superior to the LDA functional, and the PBE and AM05 functionals exhibit the best performance. In addition, we assess whether the error tendency in liquid simulations is comparable to that in solid simulations, which would suggest that the atomic volume and relative enthalpy performances are comparable between solid and liquid states but that the bulk modulus performance is not. These benchmark test results indicate that the results of liquid simulations are significantly dependent on the exchange-correlation functional and that the DFT functional performance in solid simulations can be used to roughly estimate the performance in liquid simulations.
Force-detected nanoscale absorption spectroscopy in water at room temperature using an optical trap
Authors: Parobek Alexander , Black Jacob W. , Kamenetska Maria , Ganim Ziad
Published: April 2018

Measuring absorption spectra of single molecules presents a fundamental challenge for standard transmission-based instruments because of the inherently low signal relative to the large background of the excitation source. Here we demonstrate a new approach for performing absorption spectroscopy in solution using a force measurement to read out optical excitation at the nanoscale. The photoinduced force between model chromophores and an optically trapped gold nanoshell has been measured in water at room temperature. This photoinduced force is characterized as a function of wavelength to yield the force spectrum, which is shown to be correlated to the absorption spectrum for four model systems. The instrument constructed for these measurements combines an optical tweezer with frequency domain absorption spectroscopy over the 400-800 nm range. These measurements provide proof-of-principle experiments for force-detected nanoscale spectroscopies that operate under ambient chemical conditions.
The effect of surface wettability on the performance of a piezoelectric membrane pump
Authors: Wang Jiantao , Yang Zhigang , Liu Yong , Shen Yanhu , Chen Song , Yu Jianqun
Published: April 2018

In this paper, we studied the effect of surface wettability on the bubble tolerance of a piezoelectric membrane pump, by applying the super-hydrophilic or super-hydrophobic surface to the key elements on the pump. Wettability for the flow passage surface has a direct influence on the air bubbles flowing in the fluid. Based on the existing research results, we first analyzed the relationship between the flow passage surface of the piezoelectric pump and the bubbles in the fluid. Then we made three prototypes where pump chamber walls and valve plate surfaces were given different wettability treatments. After the output performance test, results demonstrate that giving super-hydrophilic treatment on the surface of key elements can improve the bubble tolerance of piezoelectric pump; in contrast, giving super-hydrophobic treatment will reduce the bubble tolerance.
Molecular dynamics simulations of site point mutations in the TPR domain of cyclophilin 40 identify conformational states with distinct dynamic and enzymatic properties
Authors: Gur Mert , Blackburn Elizabeth A. , Ning Jia , Narayan Vikram , Ball Kathryn L. , Walkinshaw Malcolm D. , Erman Burak
Published: April 2018

Cyclophilin 40 (Cyp40) is a member of the immunophilin family that acts as a peptidyl-prolyl-isomerase enzyme and binds to the heat shock protein 90 (Hsp90). Its structure comprises an N-terminal cyclophilin domain and a C-terminal tetratricopeptide (TPR) domain. Cyp40 is overexpressed in prostate cancer and certain T-cell lymphomas. The groove for Hsp90 binding on the TPR domain includes residues Lys227 and Lys308, referred to as the carboxylate clamp, and is essential for Cyp40-Hsp90 binding. In this study, the effect of two mutations, K227A and K308A, and their combinative mutant was investigated by performing a total of 5.76 μs of all-atom molecular dynamics (MD) simulations in explicit solvent. All simulations, except the K308A mutant, were found to adopt two distinct (extended or compact) conformers defined by different cyclophilin-TPR interdomain distances. The K308A mutant was only observed in the extended form which is observed in the Cyp40 X-ray structure. The wild-type, K227A, and combined mutant also showed bimodal distributions. The experimental melting temperature, Tm, values of the mutants correlate with the degree of compactness with the K308A extended mutant having a marginally lower melting temperature. Another novel measure of compactness determined from the MD data, the “coordination shell volume,” also shows a direct correlation with Tm. In addition, the MD simulations show an allosteric effect with the mutations in the remote TPR domain having a pronounced effect on the molecular motions of the enzymatic cyclophilin domain which helps rationalise the experimentally observed increase in enzyme activity measured for all three mutations.
Dissociation cross section for high energy O2–O2 collisions
Authors: Mankodi T. K. , Bhandarkar U. V. , Puranik B. P.
Published: April 2018

Collision-induced dissociation cross section database for high energy O2–O2 collisions (up to 30 eV) is generated and published using the quasiclassical trajectory method on the singlet, triplet, and quintet spin ground state O4 potential energy surfaces. At equilibrium conditions, these cross sections predict reaction rate coefficients that match those obtained experimentally. The main advantage of the cross section database based on ab initio computations is in the study of complex flows with high degree of non-equilibrium. Direct simulation Monte Carlo simulations using the reactive cross section databases are carried out for high enthalpy hypersonic oxygen flow over a cylinder at rarefied ambient conditions. A comparative study with the phenomenological total collision energy chemical model is also undertaken to point out the difference and advantage of the reported ab initio reaction model.
Thermo-magneto-elastoplastic coupling model of metal magnetic memory testing method for ferromagnetic materials
Authors: Shi Pengpeng , Zhang Pengcheng , Jin Ke , Chen Zhenmao , Zheng Xiaojing
Published: April 2018

Metal magnetic memory (MMM) testing (also known as micro-magnetic testing) is a new non-destructive electromagnetic testing method that can diagnose ferromagnetic materials at an early stage by measuring the MMM signal directly on the material surface. Previous experiments have shown that many factors affect MMM signals, in particular, the temperature, the elastoplastic state, and the complex environmental magnetic field. However, the fact that there have been only a few studies of either how these factors affect the signals or the physical coupling mechanisms among them seriously limits the industrial applications of MMM testing. In this paper, a nonlinear constitutive relation for a ferromagnetic material considering the influences of temperature and elastoplastic state is established under a weak magnetic field and is used to establish a nonlinear thermo-magneto-elastoplastic coupling model of MMM testing. Comparing with experimental data verifies that the proposed theoretical model can accurately describe the thermo-magneto-elastoplastic coupling influence on MMM signals. The proposed theoretical model can predict the MMM signals in a complex environment and so is expected to provide a theoretical basis for improving the degree of quantification in MMM testing.
Thermal conductivity of pillared graphene-epoxy nanocomposites using molecular dynamics
Authors: Lakshmanan A. , Srivastava S. , Ramazani A. , Sundararaghavan V.
Published: April 2018

Thermal conductivity in a pillared graphene-epoxy nanocomposite (PGEN) is studied using equilibrium molecular dynamics simulations. PGEN is a proposed material for advanced thermal management applications because it combines high in-plane conductivity of graphene with high axial conductivity of a nanotube to significantly enhance the overall conductivity of the epoxy matrix material. Anisotropic conductivity of PGEN has been compared with that of pristine and functionalized carbon nanotube-epoxy nanocomposites, showcasing the advantages of the unique hierarchical structure of PGEN. Compared to pure carbon allotropes, embedding the epoxy matrix also promotes a weaker dependence of conductivity on thermal variations. These features make this an attractive material for thermal management applications.
Helium-induced electronic transitions in photo-excited Ba+–Hen exciplexes
Authors: Vindel Zandbergen Patricia , Barranco Manuel , Cargnoni Fausto , Drabbels Marcel , Pi Martí , Halberstadt Nadine
Published: April 2018

The possibility for helium-induced electronic transitions in a photo-excited atom is investigated using Ba+ excited to the 6p 2P state as a prototypical example. A diabatization scheme has been designed to obtain the necessary potential energy surfaces and couplings for complexes of Ba+ with an arbitrary number of helium atoms. It involves computing new He–Ba+ electronic wave functions and expanding them in determinants of the non-interacting complex. The 6p 2P ← 6s 2S photodissociation spectrum of He⋯Ba+ calculated with this model shows very weak coupling for a single He atom. However, several electronic relaxation mechanisms are identified, which could potentially explain the expulsion of barium ions from helium nanodroplets observed experimentally upon Ba+ photoexcitation. For instance, an avoided crossing in the ring-shaped He7Ba+ structure is shown to provide an efficient pathway for fine structure relaxation. Symmetry breaking by either helium density fluctuations or vibrations can also induce efficient relaxation in these systems, e.g., bending vibrations in the linear He2Ba+ excimer. The identified relaxation mechanisms can provide insight into helium-induced non-adiabatic transitions observed in other systems.
High-resolution infrared spectroscopy of O2H+ in a cryogenic ion trap
Authors: Kohguchi Hiroshi , Jusko Pavol , Yamada Koichi M. T. , Schlemmer Stephan , Asvany Oskar
Published: April 2018

The protonated oxygen molecule, O2H+, and its helium complex, He-O2H+, have been investigated by vibrational action spectroscopy in a cryogenic 22-pole ion trap. For the He-O2H+ complex, the frequencies of three vibrational bands have been determined by predissociation spectroscopy. The elusive O2H+ has been characterized for the first time by high-resolution rovibrational spectroscopy via its ν1 OH-stretching band. Thirty-eight rovibrational fine structure transitions with partly resolved hyperfine satellites were measured (56 resolved lines in total). Spectroscopic parameters were determined by fitting the observed lines with an effective Hamiltonian for an asymmetric rotor in a triplet electronic ground state, X̃3A′′, yielding a band origin at 3016.73 cm−1. Based on these spectroscopic parameters, the rotational spectrum is predicted, but not yet detected.
Bluish-white-light-emitting diodes based on two-dimensional lead halide perovskite (C6H5C2H4NH3)2PbCl2Br2
Authors: Cai Peiqing , Wang Xiangfu , Seo Hyo Jin , Yan Xiaohong
Published: April 2018

Bluish-white-light-emitting diodes (BWLEDs) are designed based on the two-dimensional mixed halide perovskite (C6H5C2H4NH3)2PbCl2Br2 at room temperature. Bluish-white electroluminescence devices were fabricated by a spin-coating method. The BWLEDs can be turned on at 4.9 V and depict a maximum luminance of ∼70 cd/m2 at 7 V. Low and room temperature photoluminescence spectra show the coexistence of free exciton and self-trapped exciton luminescence in a deformable lattice. The strategy of achieving white electroluminescence (EL) from mixed halide perovskite reported here can be applied to other two-dimensional perovskites to increase the optoelectronic efficiency of the device in the future.