bluuebunny/crossref_metadata_2025 huggingface dataset:
Chain‐routing scheme with compressive sensing‐based data acquisition for Internet of Things‐based wireless sensor networks
Authors: Aziz Ahmed , Osamy Walid , Khedr Ahmed M. , Salim Ahmed
Published: January 2021

The emerging Internet of Things (IoT)‐based systems that integrate diverse types of sensors, mobiles and other technologies to physical world is becoming increasingly popular for use in wide varieties of applications. Compressive sensing (CS)‐based information acquisition and in‐network compression provide an effective method for accurate data recovery at the base station (BS) with reduced cost of communication. In this study, how CS can be combined with routing protocols for gathering data in IoT‐based Wireless Sensor Networks (WSNs) in an energy‐efficient manner are examined. A novel chain‐routing scheme with CS based data acquisition is introduced that includes the following new algorithms: (1) Seed Estimation Algorithm (SEA) to find the best measurement matrix by selecting the best‐estimated seed, (2) Chain Construction Algorithm (CCA) to organise the network nodes during transmitting and receiving process, (3) Compression approach with reduced consumption of energy that improves the lifetime of the network by minimising the local data traffic, and (4) Reconstruction Algorithm (RA) that reconstructs the original data with minimum reconstruction error. Here, extensive simulation and analysis results prove the performance of our proposed method in improving the network lifetime 35% better than the ECST algorithm and 93% better than the PEGASIS algorithm. In addition, the proposed reconstruction algorithm exceeds the other reconstruction algorithms performance.
IoTHunter: IoT network traffic classification using device specific keywords
Authors: Khandait Pratibha , Hubballi Neminath , Mazumdar Bodhisatwa
Published: January 2021

With the proliferation of IoT devices, network management and security monitoring are becoming a challenge. For the timely detection of IoT device status and their behaviour, traffic classification methods are used. Herein, IoTHunter, a Deep Packet Inspection based IoT traffic classifier, is described. It extracts unique keywords comprising domain names, device names etc. to identify flows belonging to a particular device. IoTHunter automates the keyword extraction using the frequency of occurrence of words belonging to flows of different devices. To further enhance the performance, IoTHunter combines device specific keywords with MAC address of device for subsequent flow labelling. A publicly available IoT dataset is experimented and a good classification accuracy of it over a range of IoT devices is demonstrated.
Design and analysis of photonic crystal ring resonator based 6 × 6 wavelength router for photonic integrated circuits
Authors: Thirumaran Sridarshini , Dhanabalan Shanmuga Sundar , Sannasi Indira Gandhi
Published: January 2021

A photonic crystal ring resonator‐based 6 × 6 router has been designed and reported. The router is designed using silicon pillars with a refractive index of 3.47 perforated in the air background of refractive index 1 in a square lattice with a lattice constant of a = 562 nm. The router is designed to operate in the third optical window wavelength which has low loss and most widely used in optical communication systems and networks. Plane‐wave expansion and finite difference time domain method has been used to obtain the bandgap and performance of the designed router, which exhibits acceptable performance such as low insertion loss, low propagation delay, and low crosstalk. These routers will find applications in the photonic integrated circuit that paves a path to all‐optical networks.
Model reference adaptive system based sensorless vector control scheme for a 36‐pulse ac–dc converter fed 9‐level cascaded H‐bridge‐inverter driven induction motor drive
Authors: Kant Piyush , Singh Bhim
Published: January 2021

A new modular transformer based 36‐pulse ac–dc converter for a cascaded H‐bridge‐inverter fed medium voltage induction motor drive is proposed in this work. The conventional multi‐pulse ac–dc converter has only 18‐pulses in its line input current with six output dc voltages, whereas, the proposed multi‐pulse ac–dc converter has 36‐pulses in its line current with six output voltages. Due to this, the proposed medium voltage induction motor drive has improved power quality at input end. A 9‐level cascaded H‐bridge‐inverter is applied on drive side to boost the performance of medium voltage induction motor drive. A modified model reference adaptive system based speed sensorless vector control is presented in this paper. A nearest level modulation scheme is used to operate a 9‐level inverter at fundamental frequency switching over the entire speed range of an induction motor drive. The performance of this drive is verified through both simulation and experimental results.
Robust predictive current control of PWM rectifier under unbalanced and distorted network
Authors: Zhang Yongchang , Liu Xiang , Li Bingyu , Liu Jie
Published: January 2021

Model predictive current control has been proposed for the control of a pulse width modulation (PWM) rectifier due to its simple principle, and quick response. Model predictive current control achieves good performance for ideal grid voltages when an accurate inductance value is known. However, the actual grid voltages are usually unbalanced, and distorted, and the inductance used in the controller may be different from the real value due to saturation, temperature, and so on. In these conditions, the performance of a PWM rectifier deteriorates significantly due to the current harmonics, and power ripples. To cope with distorted grid voltages and inductance variations, this paper proposes a robust predictive current control for a PWM rectifier, which can achieve sinusoidal grid currents, and a constant active power even under an unbalanced and distorted network. The robustness against an inductance variation is achieved by using an extended state observer based on an ultra‐local model of the system. The current reference is calculated based on the principle of active power ripple elimination and then is tracked by predictive control. The presented experimental results prove that the proposed robust predictive current control scheme achieves good performance under a distorted network even with an inaccurate inductance value.
Unit commitment in a hybrid diesel/wind/pumped‐storage isolated power system considering the net demand intra‐hourly variability
Authors: Fernández‐Muñoz Daniel , Pérez‐Díaz Juan I.
Published: January 2021

This paper presents a novel two‐stage stochastic mixed‐integer linear programming model for the generation scheduling of a hybrid diesel/wind/pumped‐storage power system that considers the intra‐hourly net demand variability during the first stage. The model aims to minimise the scheduling cost, calculates the power system storage opportunity cost and considers that the start‐up cost of thermal units depends on the time passed since the previous shutdown in a detailed manner for the first stage (i.e. using integer variables) and in an approximate manner (relaxing the integrality constraints) for the second stage. To increase the model's computational efficiency, a solution approach based on the Benders decomposition technique is applied. The model is implemented in the real power system of El Hierro island, an isolated hybrid diesel/wind/pumped‐storage power system with a closed‐loop pumped‐storage plant and high wind power installed capacity. The schedules provided by the proposed model are compared to the ones provided by a similar model that does not consider the intra‐hourly net demand variability, resulting in generation schedules with a significantly lower wind energy curtailment. The results demonstrate the importance of considering the intra‐hourly net demand variability in order to integrate more wind energy at a moderate extra cost.
Earth fault distance estimation using travelling waves provided with triacs‐based reclosing in distribution networks
Authors: Elkalashy Nagy I. , Eldeeb Hazem K. , Kawady Tamer A. , Tarhuni Naser G. , Lehtonen Matti , Taalab Abdel‐Maksoud I. , Elsadd Mahmoud A.
Published: January 2021

This study presents an earth fault distance determination algorithm for distribution networks using active travelling waves. Three triacs are used in parallel with a three‐phase breaker poles to overcome the mechanical inequality of the poles’ reclosing times, so that the three phases are simultaneously reclosed. As the proposed fault location technique is an active type with controllable reclosing instant, the arrival time of the reflected surge from the fault point should be stamped precisely. For this purpose, three different travelling‐wave detection algorithms are evaluated including the discrete wavelet transform, Hilbert transform, and signal derivative. The fault location performance is evaluated under different fault conditions such as fault distances, fault resistances, and busbar faults. Due to utilising the reclosing transients, the proposed fault location function successfully estimates the fault distance for different earthing concepts such as unearthed, compensated, and earthed networks. This study is accomplished via simulating a typical 20 kV distribution network by the ATP/EMTP program. The results ensure the superior performance of the proposed fault distance estimation algorithm for earth faults in distribution networks.
Sizing HESS as inertial and primary frequency reserve in low inertia power system
Authors: Akram Umer , Mithulananthan N. , Shah Rakibuzzaman , Pourmousavi S. Ali
Published: January 2021

Energy storage systems are recognised as the potential solution to alleviate the impacts of reduced inertia and intermittency in power systems due to the integration of renewable energy sources. Several energy storage technologies are available in the market with diverse power and energy characteristics, operational limitations, and costs. Besides, frequency regulations in power systems have different requirements, for example, inertial response requires high power for a short period while primary frequency regulation requires steady power for a longer time. Thus, it is crucial to find out the optimum sizes and types of storage technologies for these services. In this paper, a methodology for sizing fast responsive energy storage technologies for inertial response, primary frequency regulation, and both inertial response and primary frequency regulation is developed. The sizing of storage systems for inertial response, primary frequency regulation, and both inertial response and primary frequency regulation is done separately. The sizing of storage for inertial response is done in two steps. A region reduction iterative algorithm is proposed to estimate the storage size for inertial response. The sizing of the storage system for primary frequency regulation is done analytically. The sizing methodology incorporates the frequency dynamics of storage, converters, and other associated controls that affect the frequency response. Moreover, an economic analysis is carried out to find the optimum combination of storage technologies for inertial response, primary frequency regulation, and both inertial response and primary frequency regulation services. The accuracy of the proposed sizing method has been compared with the metaheuristic algorithm based technique. The effectiveness of the proposed method is also compared with those in the literature. Simulation results show that the proposed method outperforms the existing methods in the literature. Finally, the non‐linear simulations revealed the validity of the optimal solutions.
Theoretical and experimental research to development of water‐film cooling system for commercial photovoltaic modules
Authors: da Silva Vinícius Oliveira , Martinez‐Bolanos Julio Romel , Heideier Raphael Bertrand , Gimenes André Luiz Veiga , Udaeta Miguel Edgar Morales , Saidel Marco Antônio
Published: January 2021

This work aims at developing and validating mathematical models and empirically evaluating a water‐film cooling system for commercial photovoltaic modules. Methodologically, thermal, electrical and climatological data measured in a specific purpose on‐grid outdoor test unit were used. In this work they are used to study the improvement in the performance of photovoltaic energy production due to temperature reduction. The first‐order state‐space linear parametric model presents the best performance to predict the temperature of the uncooled photovoltaic modules, with normalised mean square error (NRMSE) of 86.75%. In contrast, the non‐linear model performance of cooled photovoltaic modules is lower, with NRMSE of 44.5%; however, the results show that the performance of the complete thermoelectric model is satisfactory, with NRMSE of 76.38%. On the other hand, empirical tests showed that the cooling system reduces temperature in 15–19%, on average, and to a maximum of 35%. In terms of power, there are average gains of 5–9%, and maximum gains of 12%. Regarding gross generation, there are average gains of 2.3–6%, and maximum gains of 12%. It was concluded that it is possible to mathematically model and predict this generation using non‐linear models with a 0.2% error between modelled and measured generation.
Failure rate and downtime survey of wind turbines located in Spain
Authors: Artigao Estefania , Martin‐Martinez Sergio , Ceña Alberto , Honrubia‐Escribano Andres , Gomez‐Lazaro Emilio
Published: January 2021

Publicly available wind turbine failure rate and downtime studies are scarce in the scientific literature. Recent surveys in the field reveal that only 20 studies of wind farms based in Europe, Asia and the U.S. have been published, but there are no studies analysing wind farms located in Spain. With Spain holding the second place in terms of installed capacity in Europe, and the fifth worldwide, the importance of the Spanish wind power sector is evident. The present study comprehensively analyses the Spanish WT fleet in terms of yearly installed capacity and number of machines installed per technology and capacity ranges. The current fleet age ranges are also analysed. Under this scenario, the present work aims to contribute to the literature with a new failure rate and downtime study, where 75 WTs from six wind farms located in Spain are analysed over a period of 11 years. The most critical assemblies are identified per WT technology type and in general for the whole data set. Finally, the failure rate and downtime results obtained for the Spanish survey are compared against a selection of similar previously published studies.
Dynamic analysis and oscillation elimination of brushless doubly fed wind power generation system during symmetrical voltage dips
Authors: Nie Pengcheng , Wang Xuefan , Kong Ming
Published: January 2021

In the dynamics of grid‐connected operation of brushless doubly‐fed generators, grid voltage dips can cause the extreme imbalance between the voltage and the back electromotive forces in power winding. When these imbalances are combined with the influence of the inertia link composed of converter and generator, a serious over‐current and current oscillation forms in power winding and control winding. This paper gives a process analysis and proposes an improved control to the system during the low voltage ride through event. According to the mathematical model of the generators, the correlation between the power winding and control winding currents is established and then a fully equivalent simplified model is obtained accordingly. When the voltage suddenly drops to zero, the analytic expressions of power winding and control winding are calculated in the complex frequency domain and the influence factors of overshoot and oscillations are analyzed. The conventional control method relies on limited PI regulation that cannot eliminate the oscillations completely. It is found that after adjusting a proportional coefficient and eliminating the integral link of the control winding current controller, the order of the control system reduces. Therefore, the generation system can quickly recover to a steady state without oscillations. Finally, the analysis and improvement are verified by the simulation model and experimental results.
EDA‐based optimized global control for PV inverters in distribution grids
Authors: Cañadillas David , Valizadeh Hamed , Kleissl Jan , González‐Díaz Benjamín , Guerrero‐Lemus Ricardo
Published: January 2021

Operating distribution grids is increasingly challenging due to the increasing penetration of photovoltaic systems. To address these challenges, modern photovoltaic inverters include features for local control, which sometimes lead to suboptimal results. Improved communication infrastructure and photovoltaic inverters favour global control strategies, which receive information from all the systems in the grid. An estimation of distribution algorithm is used to optimize a global control strategy that minimizes active power curtailment and use of reactive power of the photovoltaic inverters, while maintaining voltage stability. Optimized global control outperforms every other local control evaluated in terms of apparent energy used for control (9.9% less usage compared to the second best alternative in all scenarios studied) and ranks second in terms of voltage stability (with a 0.14% of total time outside the voltage limits). Two new indicators to compare control strategies are proposed, and optimized global control strategy ranks best for both efficiency index (0.98) and average apparent power use (0.48 kVA).
Comprehensive analysis of distributed energy resource penetration and placement using probabilistic framework
Authors: Paliwal Priyanka
Published: January 2021

Integration of distributed energy resources (DERs) affect system performance in multitude of ways such as reliability, losses and voltage profile. Thus, increasing distributed energy resource penetration necessitates impact assessment particularly when DERs comprise of stochastic RES based distributed generators (DGs) and storage system. This paper presents a formulation for the analysis of DER penetration and placement on system losses and voltage profile in probabilistic framework. Penetration level has been defined, giving due consideration to stochastic behaviour of RES based distributed generators. The work presented incorporates analysis and consideration of two important factors in placement problem, that is, intermittent nature of RES based distributed generators and dual nature of storage units. In order to account for uncertainties inherently present in RES, probabilistic load flow has been used in this work. Placement problem is solved for three different penetration levels, that is, 20%, 40% and 60% using utterfly particle swarm optimisation. The impact of seasonal effect on system losses and voltage profile in correlation with penetration levels has also been investigated. Results provide useful insights for identification of optimum penetration level.
Effect of Nb addition on high-temperature oxidation behavior, oxide layer structure, and its exfoliation resistance of Ti-Nb Alloys
Authors: Miura-Fujiwara Eri , Ogawa Yuya , Niinomi Mitsuo , Yamasaki Tohru
Published: January 2021

The authors proposed an oxide coating on Ti alloys for the dental abutment tooth, and they had reported that Ti–29Nb–13Ta–4.6Zr (TNTZ) alloy forms a dense oxide layer by high-temperature oxidation. On the other hand, CP Ti forms a multilayered oxide consisted of rutile monolayers and the void layer. This morphological change by alloying is supposed to be mainly caused by Nb addition in Ti since the dense oxide layer of TNTZ mainly consists of rutile TiO2and TiNb2O7.

Therefore, in this study, oxidation behaviors of various range of Nb content of Ti-xNb alloys (x = 1 ~ 32 mol%) were investigated, and exfoliation resistance was evaluated. And in this paper, the oxide/metal interfacial microstructure of oxidized CP Ti, TNTZ alloy, and Ti-Nb alloy was studied by a transmission electron microscopy (TEM) and by a scanning transmission electron microscopy with an electron dispersive spectroscopy (STEM-EDS).

The cross-sectional observations suggested that the substrate was gradually oxidized during heat treatment, and nucleation and grain growth of TiO2and TiNb2O7proceed at the metal/oxide interface. Consequently, the gradual oxidation process in TNTZ and Ti-Nb alloys could lead to its continuous interfacial microstructure and dense oxide structure, which can achieve high exfoliation resistance.
Comparative analysis of methods to identify road sections with high accidents risk: a case study of E67 Estonia–Latvia–Lithuania corridor
Authors: Pashkevich Maria , Pashkevich Anton
Published: January 2021

E67 road is a strategically important part of a North Sea – Baltic Core Network Corridor, connecting the three Baltic States with Finland, on the one hand, and with North Eastern Poland, on the other. So-called Via Baltica corridor services more than 30 000 vehicles per day being one of the major arteries for transit and heavy good vehicles transport in the region. Annually around 8 000 road accidents with casualties occur in the three Baltic States with more than 500 fatalities a year. Relatively high road safety risk exposure requires more efficient management of infrastructure safety issues. The three Baltic States use either black spot management (BSM) or network safety management (NSM) or a combination of these two approaches to treat dangerous road sections of the network. In this article three methodologies used in the Baltic countries for dangerous road sections and spots identification were described. Quantitative analysis of dangerous sections/spots identified by the three methodologies was performed for the whole Via Baltica corridor to reveal the differences between the methods used.
Optimization of Urban Passenger Transport Route Network Parameters in Conditions of Structural Transformations of City Social and Economical Development
Authors: Belokurov Vladimir , Bedanokov Murat , Guketlev Yusuf , Tkacheva Yana , Guketlev Eljdar
Published: January 2021

This article presents the materials related to the optimization of the route network parameters of passenger transport on the example of the city of Maykop. The scheme of the main directions of the route network and the analysis of the urban transport network of the city of Maykop. Recommendations for optimizing the parameters of the route network of passenger transport in Maykop.
Сomputer-based calculation of atmospheric pollutant emissions by automobile transport at controlled crossings
Authors: Denisov Gennady , Zelikov Vladimir , Tarasova Elena , Klyavin Vladimir
Published: January 2021

The paper uses pollutant emissions calculation methods in accordance with GOST (All-Union State Standard) in combination with the method of mathematical statistics, which makes it possible to determine the amount of emissions from automobile transport, which is in line at a red traffic light in the area of a controlled intersection. The methods allow calculating such environmental indicators as the mass of pollutant emissions, the concentration of pollutants and the Air Pollution Index. The authenticity of this technique is confirmed by testing the hypothesis on the Pearson Law of distribution of pollutants. Based on the combined methodology, the software has been developed with the purpose to monitor atmospheric air pollution. This approach will make it possible to qualitatively assess the level of atmospheric air pollution and take timely measures in the event of dangerous environmental conditions.
Exact and approximate algorithms for the longest induced path problem
Authors: Marzo Ruslán G. , Ribeiro Celso C.
Published: January 2021

The longest induced path problem consists in finding a maximum subset of vertices of a graph such that it induces a simple path. We propose a new exact enumerative algorithm that solves problems with up to 138 vertices and 493 edges and a heuristic for larger problems. Detailed computational experiments compare the results obtained by the new algorithms with other approaches in the literature and investigate the characteristics of the optimal solutions.
Criminal Legal Support for Safeguarding the Citizens’ Digital Rights
Authors: Begishev Ildar , Kirpichnikov Danila , Latypova Elvira , Nechaeva Elena , Tasakov Sergei
Published: January 2021

The article discusses the active introduction of technologies based on the use of artificial intelligence, the activities of which entail the storage, transmission and processing of information circulating in information and telecommunication devices, their systems and networks. The article indicates that the amount of computing power of artificial intelligence technologies can significantly change the foundations of the functioning of information legal relations and, accordingly, the procedure and conditions for the implementation of digital rights of citizens. The inevitability of computer attacks on automated information systems using artificial intelligence, as well as the possibility of its misuse, create significant criminological risks of unauthorized access and use of citizens' digital rights by subjects through these technologies. The article examines the criminal law support for the protection of digital rights of citizens as a priority direction in the development of theory and practice of the application of criminal law institutions in the global, national and regional dimensions. The initial theses formulated in this study can be used in the future when building state policy and developing legal regulation of relations in the context of industrialization and digitalization.
Large Cities in the Process of New Industrialization
Authors: Dakhaeva Fatima
Published: January 2021

In our country, the ongoing processes of new industrialization are acquiring their own specifics, largely associated with the qualitative heterogeneity of its economic space. Large cities are one of the strongholds of the new industrialization. The following work into the concepts "new industrialization", "city". Briefly outlined existing approaches of assessing the processes of new industrialization. The work, based on the analysis of available statistical information, gives a characteristic of the processes of new industrialization in large cities of the country. It is shown that the importance of industry for the economy of these territories remains. To assess the processes of new industrialization from a qualitative point of view, the integration of available statistical information is proposed for calculating indicators in the context of large cities.
Regulations in blockchain sustainable integration into labor relations
Authors: Dolzhenko Ruslan
Published: January 2021

The study examines the regulations and laws governing blockchain in the system of labor relations. Labor relations have always been governed and controlled, due to the significant opportunism of the participants and continuous modification. The accumulation of changes should lead to the adaptation of the labor relations regulations. In this regard, the purpose of the work is to investigate the impact of the use of blockchain in the system of labor relations from the point of view of labor law to highlight opportunities and threats, to propose options for normative regulation of the use of distributed ledgers in the world of work. As a result of the study, gaps in labor law have been highlighted that do not allow using the full potential of blockchain. It is proposed to supplement the Labor Code of the Russian Federation with a section that regulates the use of digital technologies in the regulation of labor relations. The key conclusion of the study is that the positive impact of blockchain on labor relations is minimized due to the lack of a legal foundation in this area.
Activization of Scientific and Innovative Sphere for the Region Sustainable Development
Authors: Chulkova Galina , Vorobeva Elena , Vorobev Oleg
Published: January 2021

The region sustainable development presupposes the creation of conditions ensuring the progressive development to achieve a qualitatively new state of the regional economy. One of the strategic goals of the social and economic development of Smolensk Region is the intellectual property market infrastructure development, the provision of technology transfer and the stimulation of inventive activity in the region. The analysis of the rating of Russian innovative regions showed that according to the most important indicators of innovative activity in industrial production, Smolensk region is in the first half of the all-Russian rating of regions, and the lower activity in research and development is complemented by low indicators of patent activity in Smolensk region in comparison with the average Russian indicator values. In this regard, the issues of the formation and use of the intellectual activity results were identified and priority directions were developed to activate the scientific and innovative sphere of Smolensk region.
Research of visual political communication perception by youth: psychophysiological approach
Authors: Eremenko Yulia , Chentsova Anna , Kuzmenko Anastasiia
Published: January 2021

It is proposed to use objective methods to assess the perception of visual political content for planning an effective communication strategy by the actors of political power Two experiments were conducted in the work. The first one investigates the visual attention and memorization of different types of political content (memes, photographs of political leaders, photographs of political events and posters) by young people based on the oculographic method. The second experiment is aimed at studying the emotional reactions of young people to the perception of political video content of different genres: humorous, video memes, speech of a political leader and disgusting video. An adapted version of the Differentiated Emotions Scale (DES) was used for the evaluation.
An Ugi Reaction/Intramolecular Cyclization/Oxidation Cascade towards Tetrazole-Linked Dibenzoxazepines
Authors: Dömling Alexander , Zheng Qiang , Boltjes André
Published: January 2021

A series of tetrazole-linked dibenzo[b,f][1,4]oxazepines is synthesized through a short sequence involving an Ugi tetrazole reaction. The intermediate tetrazole undergoes a potassium carbonate mediated SNAr cyclization, followed by oxidation to afford the target tricyclic heterocyclic scaffold. The optimization, scope and limitations of this two-step and efficient methodology are investigated. A 1000-member library of tetrazole-linked dibenzo[b,f][1,4]oxazepines is generated and the physicochemical properties are analyzed. great
Driving forces analysis of CO2 emissions from China's electric industry based on two-phase LMDI decomposition method
Authors: Li Rong , Dong Jun , Pa Lidan
Published: January 2021

The electric power sector is the largest contributor of CO2 emissions in China. With an increasing concern about environment problems, it is essential to identify key factors that affect CO2 emissions from China's electric power industry so as to help the fossil fuel-based country reduce carbon emissions. For this purpose, the two-phase Logarithmic Mean Division Index (LMDI) decomposition method is presented in this paper. Covering the whole industry chain including power generation, transmission, and consumption, the two-phase LMDI decomposition model is constructed. Then, the influencing aspects are decomposed into ten driving factors, namely, (1) fossil energy power generation structure, (2) fossil energy consumption coefficient, (3) thermal power proportion, (4) power generation and consumption ratio, (5) transmission and distribution loss, (6) industrial power consumption intensity, (7) industrial structure, (8) per capita gross domestic product (GDP), (9) total population, and (10) resident power consumption intensity. Based on data from China statistical yearbook, China energy statistics yearbook, and China power statistics yearbook (2005–2017 edition), the decomposition calculation results show that the power generation and consumption ratio, industrial structure, resident power consumption intensity, per capita GDP, population size, and transmission and distribution loss factors are positive driving factors with contributions of 1.2%, 2.47%, 1.5%, 94.29%, 5.43%, and 4.64%, respectively. However, the fossil energy power generation structure, fossil energy consumption coefficient, thermal power proportion, and industrial power consumption intensity are negative driving factors with contribution rates of −0.34%, −21.72%, −9.85%, and −8.44%, respectively. According to the main effect factors identified, some corresponding measures are proposed to reduce carbon emissions from China's power industry.
Scaling laser preheat for MagLIF with the Z-Beamlet laser
Authors: Weis M. R. , Harvey-Thompson A. J. , Ruiz D. E.
Published: January 2021

Optimizing the performance of the Magnetized Liner Inertial Fusion (MagLIF) platform on the Z pulsed power facility requires coupling greater than 2 kJ of preheat energy to an underdense fuel in the presence of an applied axial magnetic field ranging from 10 to 30 T. Achieving the suggested optimal preheat energies has not been experimentally achieved so far. In this work, we explore the preheat design space for cryogenically cooled MagLIF targets, which represent a viable candidate for increasing preheat energies. Using 2D and 3D HYDRA MHD simulations, we first discuss the various physical effects that occur during laser preheat, such as laser energy deposition, self-focusing, and filamentation. After identifying the changes that different phase plates, gas-fill densities, and magnetic fields bring to the aforementioned physical effects, we, then, consider higher laser energies that are achievable with modest upgrades to the Z Beamlet laser. Finally, with a 6.0-kJ upgraded laser, 3D calculations suggest that it is possible to deliver 4.25 kJ into the MagLIF fuel, resulting in an expected deuterium neutron yield of YDD≃1.5×1014, or roughly 50 kJ of DT equivalent yield, at 20-MA current drive. This represents a 10-fold increase in the currently achieved yields for MagLIF.
Theoretical and experimental study of a monocharged electret for pressure sensor applications
Authors: Gong Shaobo , Zhang Jinxi , Wang Chenchen , Ren Kailiang
Published: January 2021

Electromechanical sensors play a large role in the development of artificial intelligence and the Internet of Things. In previous studies, it was found that monocharged electret nanogenerator (MENG)-based sensors exhibited a much-improved sensitivity and output performance compared to metallized electret-based devices. However, theoretical studies on MENG sensors are still lacking. This investigation is the first attempt at establishing a systematic theoretical model for MENG devices. The derived equations indicated that the output voltage of the device was proportional to the applied pressure, and that the sensitivity of the MENG device was only dependent on the device structure and charge density on the electret material. Furthermore, a fabricated MENG device demonstrated that its output voltage of the MENG device was proportional to the applied pressure and remained constant in a low frequency range. Moreover, both the sensitivity and current density of the device decreased with increasing l1. For a real device, Isc of the device reached a maximum value at an l2 of 0.3 mm and then started to decrease. Due to their advantageous flexibility, high sensitivity, and ease of fabrication, MENG devices show great promise for wearable devices and energy harvesting applications.
Normal forms and averaging in an acceleration problem in nonholonomic mechanics
Authors: Bizyaev Ivan , Bolotin Sergey , Mamaev Ivan
Published: January 2021

This paper investigates nonholonomic systems (the Chaplygin sleigh and the Suslov system) with periodically varying mass distribution. In these examples, the behavior of velocities is described by a system of the form dvdτ=f2(τ)u2+f1(τ)u+f0(τ),dudτ=−uv+g(τ), where the coefficients are periodic functions of time τ with the same period. A detailed analysis is made of the problem of the existence of modes of motion for which the system speeds up indefinitely (an analog of Fermi’s acceleration). It is proved that, depending on the choice of coefficients, variable v has the asymptotics t1k,k=1,2,3. In addition, we show regions of the phase space for which the system, when the trajectories are started from them, is observed to speed up. The proof uses normal forms and averaging in a slightly unusual form since unusual form averaging is performed over a variable that is not fast.
Selectively boron doped homoepitaxial diamond growth for power device applications
Authors: Lloret F. , Eon D. , Bustarret E. , Donatini F. , Araujo D.
Published: January 2021

Diamond lateral growth is a powerful technique for the design and fabrication of diamond-based power electronic devices. Growth orientation affects the diamond deposition in terms of growth rate, surface roughness, and impurity incorporation. It has been shown that the finally grown surface of a patterned substrate can be predesigned based on the growth conditions. Thus, simultaneous growth along different surface orientations yields regions with different properties. In line with this, the incorporation of boron in a microwave plasma enhanced chemical vapor deposition laterally deposited epilayer over a mesa patterned {100}-oriented diamond substrate was studied by cathodoluminescence. It was observed that laterally oriented facets were highly boron doped in contrast to the {100}-oriented surfaces, which did not show any bound exciton emission, related to the doping. This study shows that, by designing the initial pattern and tuning the conditions, it is possible to drive a selective incorporation of boron into the grown layer.
Surface-enhanced hyper-Raman scattering of Rhodamine 6G isotopologues: Assignment of lower vibrational frequencies
Authors: Olson Jacob E. , Hu Zhongwei , Best Michael D. , Jensen Lasse , Camden Jon P.
Published: January 2021

We report a comprehensive experimental and theoretical study of the lower-wavenumber vibrational modes in the surface-enhanced hyper-Raman scattering (SEHRS) of Rhodamine 6G (R6G) and its isotopologue R6G-d4. Measurements acquired on-resonance with two different electronic states, S1 and S2, are compared to the time-dependent density functional theory computations of the resonance hyper-Raman spectra and electrodynamics-quantum mechanical computations of the SEHRS spectra on-resonance with S1 and S2. After accounting for surface orientation, we find excellent agreement between experiment and theory for both R6G and its isotopologue. We then present a detailed analysis of the complex vibronic coupling effects in R6G and the importance of surface orientation for characterizing the system. This combination of theory and experiment allows, for the first time, an unambiguous assignment of lower-wavenumber vibrational modes of R6G and its isotopologue R6G-d4.
Stability of β-Nb phase in Zr–Nb alloys under neutron irradiation: Phase field modeling
Authors: Kharchenko Dmitrii O. , Kharchenko Vasyl O. , Bashtova Anna I. , Kupriienko Viktor V. , Wu Lu
Published: January 2021

A phase field approach to study stability of β-Nb precipitates in Zr–Nb alloys is extended by taking into account local rearrangement of point defects and misfit dislocations. Kinetic properties of β-Nb phase formation are discussed at a heat treatment stage. Stability of secondary phase precipitates is studied at different irradiation temperatures and dose rates. It is shown that processes of dissolution/growth of precipitates are governed by the competition of ballistic mixing and thermal diffusion. It is found that at large values of dose rates and low temperatures, precipitates are dissolved due to a major role of ballistic mixing, whereas at low dose rate and elevated temperatures, β-niobium particles grow slowly by an Ostwald ripening scenario up to 1–2 nm due to the dominant role of thermal diffusion. Misfit dislocations sustain the existence of Nb-enriched domains of mixed symmetry. It is shown that growing dislocation loops and dissolving/growing precipitates result in the hardening change up to 0.01% at a dose rate of 10−5dpa/s and temperatures of 550–575 K. Obtained theoretical results are verified by experimental data.
An information-theoretic approach to infer the underlying interaction domain among elements from finite length trajectories in a noisy environment
Authors: Basak Udoy S. , Sattari Sulimon , Hossain Md. Motaleb , Horikawa Kazuki , Komatsuzaki Tamiki
Published: January 2021

Transfer entropy in information theory was recently demonstrated [Basak et al., Phys. Rev. E 102, 012404 (2020)] to enable us to elucidate the interaction domain among interacting elements solely from an ensemble of trajectories. Therefore, only pairs of elements whose distances are shorter than some distance variable, termed cutoff distance, are taken into account in the computation of transfer entropies. The prediction performance in capturing the underlying interaction domain is subject to the noise level exerted on the elements and the sufficiency of statistics of the interaction events. In this paper, the dependence of the prediction performance is scrutinized systematically on noise level and the length of trajectories by using a modified Vicsek model. The larger the noise level and the shorter the time length of trajectories, the more the derivative of average transfer entropy fluctuates, which makes the identification of the interaction domain in terms of the position of global minimum of the derivative of average transfer entropy difficult. A measure to quantify the degree of strong convexity at the coarse-grained level is proposed. It is shown that the convexity score scheme can identify the interaction distance fairly well even while the position of the global minimum of the derivative of average transfer entropy does not. We also derive an analytical model to explain the relationship between the interaction domain and the change in transfer entropy that supports our cutoff distance technique to elucidate the underlying interaction domain from trajectories.
First-principles study on photoelectric and transport properties of CsXBr3 (X = Ge, Sn) and blue phosphorus van der Waals heterojunctions
Authors: Yao Mengli , Zhang Xiaojiao , Wu Tian , Liu Biao , Li Mingjun , Long Mengqiu
Published: January 2021

The electronic structures, charge mobility, and optical properties of the CsXBr3 (X = Ge and Sn) perovskite cells and blue phosphorus (BP) van der Waals heterojunctions have been investigated by using the first-principles method based on density functional theory. We found that the electronic band structures of layered BP and perovskite cells are still retained, a type II band arrangement can be observed in the heterojunctions, and the bandgaps of the heterojunctions gradually decrease with the increase in the number of perovskite layers. Additionally, electrons and holes are gathered at the BP and the perovskite interface of the heterojunctions, respectively. The potential difference formed by net charge aggregation at the BP and perovskite interface can result in a built-in electric field, which promotes the separation of electrons and holes. The maximum carrier mobility of the CsGe(Sn)Br3/BP heterojunctions can reach up to 7.364 × 103 (7.815 × 103) cm2 V−1 s−1 along the y direction of the electron in the CG(S)B/BP heterojunctions by the Boltzmann transport method. Moreover, due to the retention of the high absorption coefficient of monolayer BP, the light absorption spectra of the heterojunctions are obviously increased in the visible and purple light regions, and the absorption coefficient is as high as 105 cm−1, indicating that the heterojunctions could be potentially applied to various optoelectronic devices and solar cells.
Nuclear polarization effects in cryptochrome-based magnetoreception
Authors: Wong Siu Ying , Solov’yov Ilia A. , Hore P. J. , Kattnig Daniel R.
Published: January 2021

The mechanism of the magnetic compass sense of migratory songbirds is thought to involve magnetically sensitive chemical reactions of light-induced radical pairs in cryptochrome proteins located in the birds’ eyes. However, it is not yet clear whether this mechanism would be sensitive enough to form the basis of a viable compass. In the present work, we report spin dynamics simulations of models of cryptochrome-based radical pairs to assess whether accumulation of nuclear spin polarization in multiple photocycles could lead to significant enhancements in the sensitivity with which the proteins respond to the direction of the geomagnetic field. Although buildup of nuclear polarization appears to offer sensitivity advantages in the more idealized model systems studied, we find that these enhancements do not carry over to conditions that more closely resemble the situation thought to exist in vivo. On the basis of these simulations, we conclude that buildup of nuclear polarization seems unlikely to be a source of significant improvements in the performance of cryptochrome-based radical pair magnetoreceptors.
Reagent integration and controlled release for multiplexed nucleic acid testing in disposable thermoplastic 2D microwell arrays
Authors: Padmanabhan S. , Sposito A. , Yeh M. , Everitt M. , White I. , DeVoe D. L.
Published: January 2021

The seamless integration of reagents into microfluidic devices can serve to significantly reduce assay complexity and cost for disposable diagnostics. In this work, the integration of multiplexed reagents into thermoplastic 2D microwell arrays is demonstrated using a scalable pin spotting technique. Using a simple and low-cost narrow-bore capillary spotting pin, high resolution deposition of concentrated reagents within the arrays of enclosed nanoliter-scale wells is achieved. The pin spotting method is further employed to encapsulate the deposited reagents with a chemically modified wax layer that serves to prevent disruption of the dried assay components during sample introduction through a shared microchannel, while also enabling temperature-controlled release after sample filling is complete. This approach supports the arbitrary patterning and release of different reagents within individual wells without crosstalk for multiplexed analyses. The performance of the in-well spotting technique is characterized using on-chip rolling circle amplification to evaluate its potential for nucleic acid-based diagnostics.
Surface acoustic waves increase magnetic domain wall velocity
Authors: Adhikari A. , Adenwalla S.
Published: January 2021

Domain walls in magnetic thin films are being explored for memory applications and the speed at which they move has acquired increasing importance. Magnetic fields and currents have been shown to drive domain walls with speeds exceeding 500 m/s. We investigate another approach to increase domain wall velocities, using high frequency surface acoustic waves to create standing strain waves in a 3 micron wide strip of magnetic film with perpendicular anisotropy. Our measurements, at a resonant frequency of 248.8 MHz, indicate that domain wall velocities increase substantially, even at relatively low applied voltages. Our findings suggest that the strain wave derived effective magnetic field acts as an additional driver for domain wall motion.
Locally transitive analytic actions of Lie groups on compact surfaces
Authors: Gorbatsevich V. V.
Published: January 2021

We investigate locally transitive analytic actions of Lie groups on surfaces. We indicate compact surfaces on which locally transitive actions of Lie groups can be globalized (in particular, with certain conditions on the set of fixed points) and describe the schemes of irreducible locally transitive actions of Lie groups on these surfaces.

Bibliography: 13 titles.
Towards finite generation of higher rational rank valuations
Authors: Xu C.
Published: January 2021

We propose a finite generation conjecture for the valuation which computes the stability threshold of a log Fano pair. We also initiate a degeneration strategy for attacking the conjecture.

Bibliography: 17 titles.