bluuebunny/crossref_metadata_2025 huggingface dataset:
Multi-vector activity in the introduction of integrated administration of environmentally safe nature resources use
Authors: Kovshun Nataliia , Kostrychenko Valentyna , Semeniuk Kateryna , Filipishyna Liliya , Antonova Liudmyla
Published: May 2021

The purpose of the article is to build a multi-vector structure of integrated governing of environmentally safe nature resources use according to the principles of a circular economy approach. Based on the the method of mode indicators and the method of fuzzy logic, the index of environmental safety of nature management has been determined. The interpretation of the essence of integrated administration of environmentally safe nature management is given. The organizational and economic mechanism and its implementation has been displayed. The mechanism of integral management as a set of appropriate measures is considered. A multi-vectoral structure is built, which provides for the formation of a system of mechanisms with adequate levers and tools. The providing, adaptive, functional, effective-target subsystem is characterized. The indicators of environmental, economic and social efficiency are determined, which are targeted guidelines when implementing integrated management. The requirements of a systematic approach for a comprehensive implementation of integrated management of natural resource potential are taken into account.
Trade-economic cooperation of Ukraine and China within COVID-19 Pandemic and in post-pandemic time
Authors: Yatsenko Olha , Tsygankova Tetiana , Horbachova Iryna , Aksyonova Oksana , Osadchuk Valeriia
Published: May 2021

Modern trends of trade-economic relations of the countries within the COVID-19 pandemic have been systemized in the development of mutual relations in particular economy sectors have been identified. Direct connection between the increase of export volume to China and Ukraine GDP growth has been established in the study based on the correlation-regression analysis. Weaknesses and strengths as well as opportunities and threats of mutual relations within the pandemic have been defined. The influence of the world crisis, creating a free trade area, and other factors on foreign trade circulation between Ukraine and China have been studied with the tools of empirical gravity model of international trade. Foreign trade circulation up until 2022 with and without creating a Free Trade Area has been forecast based on the modelled data. Perspective directions of trade-economic relations have been defined; the strategy of extending the trade-economic integration of Ukraine and China within the COVID-19 pandemic and in post-pandemic time within customs tariffs liberalization, intensification of symmetric interdependence and complementarity between the countries, within creating a free trade area, diversifying trade turnovers, overcoming the pandemic, reduction of crisis consequences, and strengthening cooperation in new industries of post-pandemic time has been grounded.
Imperatives for the formation and development of the circular economy and global waste management
Authors: Khomenko Inna , Vuychenko Marina , Gomeniuk Maryna , Mazur Yurii , Haidai Oksana
Published: May 2021

The world ecological problem of waste accumulation, environmental pollution and the need to develop a circular economy are described. The aim of the article is to show the advantage of using a circular economy in the management of the national economy. It is substantiated that resource management should radically change from a linear model of accept-use-dispose to a more stable, circular model. It is proved that the principles of circular economy are not based on the management of material and waste flows, but on more valuable methods, such as maintenance, recycling and reuse. Different models of circular economy and their shortcomings are considered. Based on practical world experience in implementing the concept of circular economy, 5 main circular business models are identified. It has been established that circular supply chains that minimize waste and seek to reuse, repair and recycle where waste cannot be prevented should be more sustainable than the linear systems they replace. It was found that in the absence of effective resource management, the current environmental situation will lead to fatal consequences, which confirms the need for public administration to ensure the use of a circular economy.
Sustainable development: trends and realities of Ukraine
Authors: Kuzmak Olena , Kuzmak Oleh , Pohrishchuk Borys
Published: May 2021

The purpose of the article is to analyze the current state of the principles of sustainable development of enterprises in Ukraine, and the impact on the economy of Ukraine as a whole. To this end, was performed an analysis of Ukraine’s position on the indicators of sustainable development in the dynamics. The article defines the essence of the concept of sustainable development and its main components: economic, environmental and social. The basic principles of ensuring sustainable business development are determined. The prerequisites for ensuring and supporting the implementation of the concept of sustainable development of the enterprise in management practice are considered. The proposals on the innovative nature of economic development in the context of sustainable development of domestic enterprises are studied and substantiated. It was found that the current situation in the economy of Ukraine is characterized by not very high activity of innovation, which is caused primarily by the deficiency of own funds of enterprises and limited budget funding. The ways of transition of the national economy, in particular of domestic enterprises to the model of sustainable development are suggested.
A stability theorem for equilibria of delay differential equations in a critical case with application to a model of cell evolution
Authors: Amin Karim , Badralexi Irina , Halanay Andrei , Mghames Ragheb
Published: May 2021

In this paper the stability of the zero equilibrium of a system with time delay is studied. The critical case of a multiple zero root of the characteristic equation of the linearized system is treated by applying a Malkin type theorem and using a complete Lyapunov-Krasovskii functional. An application to a model for malaria under treatment considering the action of the immune system is presented.
The Challenge of Information and Communications Technology in Education
Authors: Ilic Peter
Published: May 2021

The dramatic impact of Information and Communications Technology (ICT) on society suggests the potential for an analogous effect on education. The prospects for some benefit from the affordances offered by ICT are appealing but not entirely understood by many educators. The challenges of design, implementation, assessment, and analysis of ICT supported education are considerable. These challenges include how ICT can support traditional learning approaches, add new educational opportunities, and reduce resistance to introducing disruptive technologies such as smartphones. The affordances of ICT in education open many possibilities to integrate with and support existing curriculums. However, many educational institutions have not fully embraced these opportunities. This paper will explore some barriers to ICT adoption in the educational context. The first section is a brief introduction followed by a section on the history of educational theory to illustrate the considerable body of knowledge available on this topic. The third section introduces a type of case study of the challenges faced by a nation in providing the infrastructure needed to implement many of these technologies. Section four gives a summary of many, but not all, barriers to technology adoption faced by educational administrators, instructional designers, educators, and learners. And the final section is a brief conclusion.
Promoting English Speaking Confidence through Online Expanding Circle Communication
Authors: Saito Arifumi , Heo Younghyon
Published: May 2021

This study explores how expanding circle communication (i.e., intercultural communication between “non-native” speakers of English) boosts the confidence of Japanese EFL learners by developing a positive attitude toward their own English. Japanese, Chinese and Vietnamese university students participated in four sessions of online discussion. Since the idea of “English as an International Language” (EIL) is considered as a key to promote the learners’ positive mindset for what had been considered “non-native” English varieties and boost the confidence in their own English, it was introduced in the reading activities in each session. After the completion of four intercultural communication sessions, reflective writings on two questions asking 1) their self-confidence in speaking English and 2) their attitude about EIL were collected. The result shows that the expanding circle communication brought the Japanese participants to raise their confidence in speaking English in relatively high percentage (73%) of all cases. Regarding the attitude on EIL, on the other hand, students were divided into two groups with the negative (43%) and positive (57%) attitude. In this study, therefore, the gap in the percentage between the participants’ confidence in speaking English and attitude on EIL was examined and discussed.
A Contemporary Machine Learning Method for Accurate Prediction of Cervical Cancer
Authors: Jeremiah Tanimu Jesse , Hamada Mohamed , Hassan Mohammed , Yusuf Ilu Saratu
Published: May 2021

With the advent of new technologies in the medical field, huge amounts of cancerous data have been collected and are readily accessible to the medical research community. Over the years, researchers have employed advanced data mining and machine learning techniques to develop better models that can analyze datasets to extract the conceived patterns, ideas, and hidden knowledge. The mined information can be used as a support in decision making for diagnostic processes. These techniques, while being able to predict future outcomes of certain diseases effectively, can discover and identify patterns and relationships between them from complex datasets. In this research, a predictive model for predicting the outcome of patients’ cervical cancer results has been developed, given risk patterns from individual medical records and preliminary screening tests. This work presents a Decision tree (DT) classification algorithm and shows the advantage of feature selection approaches in the prediction of cervical cancer using recursive feature elimination technique for dimensionality reduction for improving the accuracy, sensitivity, and specificity of the model. The dataset employed here suffers from missing values and is highly imbalanced. Therefore, a combination of under and oversampling techniques called SMOTETomek was employed. A comparative analysis of the proposed model has been performed to show the effectiveness of feature selection and class imbalance based on the classifier’s accuracy, sensitivity, and specificity. The DT with the selected features and SMOTETomek has better results with an accuracy of 98%, sensitivity of 100%, and specificity of 97%. Decision Tree classifier is shown to have excellent performance in handling classification assignment when the features are reduced, and the problem of imbalance class is addressed.
Real-time Hand-Gesture Recognition based on Deep Neural Network
Authors: Ageishi Naoto , Tomohide Fukuchi , Ben Abdallah Abderazek
Published: May 2021

Hand gestures are a kind of nonverbal communication in which visible bodily actions are used to communicate important messages. Recently, hand gesture recognition has received significant attention from the research community for various applications, including advanced driver assistance systems, prosthetic, and robotic control. Therefore, accurate and fast classification of hand gesture is required. In this research, we created a deep neural network as the first step to develop a real-time camera-only hand gesture recognition system without electroencephalogram (EEG) signals. We present the system software architecture in a fair amount of details. The proposed system was able to recognize hand signs with an accuracy of 97.31%.
“Hyperwiper”: Dancing windshield wipers Synchronizing Windshield Wipers with Sound Entertainment System Inside Vehicles
Authors: Oudendijk Rob , Hayashi Yuka , Arevalo Camilo , Villegas Julián , Kudry Peter , Cohen Michael
Published: May 2021

Instead of adding to the driving cacophony, actively orchestrated windshield wipers can enhance musical audition, reinforcing a beat by augmenting the rhythm, increasing the signal:noise ratio by aligning the cross-modal rhythmic beats and masking the noise, providing “visual music,” the dance of the wipers. We recast the windshield wipers of an automobile with advanced multimedia technology, allowing wipers to dance to music.
Lossless text compression using GPT-2 language model and Huffman coding
Authors: Rahman Md. Atiqur , Hamada Mohamed
Published: May 2021

Modern daily life activities produced lots of information for the advancement of telecommunication. It is a challenging issue to store them on a digital device or transmit it over the Internet, leading to the necessity for data compression. Thus, research on data compression to solve the issue has become a topic of great interest to researchers. Moreover, the size of compressed data is generally smaller than its original. As a result, data compression saves storage and increases transmission speed. In this article, we propose a text compression technique using GPT-2 language model and Huffman coding. In this proposed method, Burrows-Wheeler transform and a list of keys are used to reduce the original text file’s length. Finally, we apply GPT-2 language mode and then Huffman coding for encoding. This proposed method is compared with the state-of-the-art techniques used for text compression. Finally, we show that the proposed method demonstrates a gain in compression ratio compared to the other state-of-the-art methods.
Team Activity of Robot Competition of Simulated Robot in World Robot Summit 2020
Authors: Shima Daichi , Furukawa Tomoyuki , Aoba Ryuma , Ohashi Ayato , Tsuruno Kota , Naruse Keitaro
Published: May 2021

World Robot Summit (WRS) has several robot competitions, and we will participate it in the infrastructure and disaster response category. Participating teams develop their robot system by teleoperation and/or autonomous operation and run it in a set of courses modelling and simplifying disaster responding situations. The authors will attend the challenge of the tunnel disaster response and recovery, in which we are requested to achieve an investigation and rescue scenario of a tunnel fire with simulated robots. As preparation, we develop simulated robot models and corresponding software as a team. In this article, we report out activity to the robot competition and student’s project-based learning by joining it.
Spatial Navigation by Seated Users of Multimodal Augmented Reality Systems
Authors: Martens William L. , Cohen Michael
Published: May 2021

When seated users of multimodal augmented reality (AR) systems attempt to navigate unfamiliar environments, they can become disoriented during their initial travel through a remote environment that is displayed for them via that AR display technology. Even when the multimodal displays provide mutually coherent visual, auditory, and vestibular cues to the movement of seated users through a remote environment (such as a maze), those users may make errors in judging their own orientation and position relative to their starting point, and also may have difficulty determining what moves to make in order to return themselves to their starting point. In a number of investigations using multimodal AR systems featuring realtime servocontrolled movement of seated users, the relative contribution of spatial auditory display technology was examined across a variety of spatial navigation scenarios. The results of those investigations have implications for the effective use of the auditory component of a multimodal AR system in applications supporting spatial navigation through a physical environment.
Verhalten verändern – AP/CP-Intervention
Authors: Walser Annika , Wildhaber-Phillips Chantal
Published: May 2021

Wer schon einmal versucht hat, mit dem Rauchen aufzuhören oder mehr Sport zu treiben, kennt das: Aus gewohnten Verhaltensmustern auszubrechen ist gar nicht so leicht. Zwei Ergotherapeutinnen haben eine Interventionsstrategie zur Verhaltensänderung entwickelt, die auf einem psychologischen Modell beruht.
Joint Effect of Multiple Prothrombotic Genotypes and Obesity on the Risk of Incident Venous Thromboembolism
Authors: Frischmuth Tobias , Hindberg Kristian , Gabrielsen Maiken E. , Brumpton Ben , Hveem Kristian , Brækkan Sigrid K. , Hansen John-Bjarne , Morelli Vânia M.
Published: May 2021

Background The impact of the combination of obesity and multiple prothrombotic genotypes on venous thromboembolism (VTE) risk remains unclear.

Objective To investigate the joint effect of obesity and a genetic risk score (GRS) composed of established prothrombotic single nucleotide polymorphisms (SNPs) on VTE risk using a population-based case–cohort.

Methods Cases with incident VTE (n = 1,470) and a subcohort (n = 12,826) were derived from the Tromsø Study (1994–2012) and the Trøndelag Health Study (HUNT) (1995–2008). Participants were genotyped for ABO (rs8176719), F5 (rs6025), F2 (rs1799963), FGG (rs2066865), and F11 (rs2036914) SNPs. Age- and sex-adjusted hazard ratios (HRs) were estimated according to body mass index (BMI) categories and number of risk alleles for individual SNPs and the GRS (0–1, 2, 3, ≥4 alleles).

Results The combination of obesity (BMI ≥ 30kg/m2) and risk alleles, either as individual SNPs or as a GRS, had an additive effect on VTE risk (i.e., no biological interaction). Obese subjects who were carriers of ≥4 risk alleles had a 2.85-fold (95% confidence interval [CI]: 2.05–3.96) increased risk of overall VTE compared with those with BMI <25 kg/m2 and 0 to 1 risk allele. However, in subgroups, the combination of obesity and ≥4 risk alleles was more pronounced for deep vein thrombosis (DVT) (HR: 3.20; 95% CI: 2.09–4.90) and unprovoked VTE (HR: 3.82; 95% CI: 2.25–6.47), suggesting a supra-additive effect.

Conclusion Our findings indicate that the combination of obesity and GRS has an additive effect on the risk of overall VTE. However, it may have a supra-additive effect on the risk of DVT and unprovoked VTE.
Microsurgical Resection of Tuberculum Sellae Meningioma through Pterional Approach with Extradural Optic Canal Unroofing
Authors: Matsuo Satoshi , Amano Toshiyuki , Yamashita Sojiro , Miyamatsu Yuichiro , Nakamizo Akira
Published: May 2021

Tuberculum sellae meningiomas pose significant challenges because they are surrounded by crucial neurovascular structures, such as the optic and oculomotor nerves, pituitary stalk, internal carotid artery and its branches, and the anterior cerebral arteries. Even if small, such meningiomas frequently extend to the optic canal that is considered a poor prognostic factor for vision. In this video clip, we illustrate the case of a 60-year-old female who had an approximately 3-cm tuberculum sellae meningioma with optic canal involvement. She underwent surgical resection of the tumor through a pterional approach. After extradural optic canal unroofing, detaching, devascularizing, and debulking the tumor, careful dissection of the meningioma from the surrounding tissues was performed. Next, the tumor extensions into both of the optic canals were removed. Finally, coagulation and resection of the tumor origin on the dura of the tuberculum sellae following Simpson's grade-I resection were performed. Histopathology revealed that the tumor was a World Health Organization (WHO) grade-I meningioma. The patient had an uneventful postoperative course and her visual acuity was preserved, with no visual field defect on postoperative visual examination. In this video, the basic surgical techniques in performing extradural optic canal unroofing, preserving the arachnoid plane, and stay in collect layer, which is the essential technique for dissecting meningiomas and for preserving neurovascular structures, are demonstrated.

The link to the video can be found at: https://youtu.be/vD54Iji0C4Q.
Functional bionanomaterials help optimize surface engineering to improve cancer immunotherapy
Authors: Song Wantong
Published: May 2021

A review summarizes using bionanomaterials for cell surface engineering – both ex vivo and in vivo – in cancer immunotherapy.
Capturing fingerprints of conical intersection: Complementary information of non-adiabatic dynamics from linear x-ray probes
Authors: Jadoun Deependra , Gudem Mahesh , Kowalewski Markus
Published: May 2021

Many recent experimental ultrafast spectroscopy studies have hinted at non-adiabatic dynamics indicating the existence of conical intersections, but their direct observation remains a challenge. The rapid change of the energy gap between the electronic states complicated their observation by requiring bandwidths of several electron volts. In this manuscript, we propose to use the combined information of different x-ray pump-probe techniques to identify the conical intersection. We theoretically study the conical intersection in pyrrole using transient x-ray absorption, time-resolved x-ray spontaneous emission, and linear off-resonant Raman spectroscopy to gather evidence of the curve crossing.
Monodisperse patchy particle glass former
Authors: Marín-Aguilar Susana , Smallenburg Frank , Sciortino Francesco , Foffi Giuseppe
Published: May 2021

Glass formers are characterized by their ability to avoid crystallization. As monodisperse systems tend to rapidly crystallize, the most common glass formers in simulations are systems composed of mixtures of particles with different sizes. Here, we make use of the ability of patchy particles to change their local structure to propose them as monodisperse glass formers. We explore monodisperse systems with two patch geometries: a 12-patch geometry that enhances the formation of icosahedral clusters and an 8-patch geometry that does not appear to strongly favor any particular local structure. We show that both geometries avoid crystallization and present glassy features at low temperatures. However, the 8-patch geometry better preserves the structure of a simple liquid at a wide range of temperatures and packing fractions, making it a good candidate for a monodisperse glass former.
Disruption mitigation using ion cyclotron wave in ADITYA tokamak
Authors: Ghosh J. , Tanna R. L. , Chattopadhyay P. K. , Sen A. , Raj Harshita , Dhyani Pravesh , Dolui Suman , Kulkarni S. V. , Mishra K. , Singh Raj , Kumar Sunil , Bhatt S. B. , Jadeja K. A. , Patel K. M. , Gupta C. N. , Makwana Moti M. , Shah K. , Chavda Chhaya , Panchal V. K. , Patel N. C. , Raval J. V. , Purohit Shishir , Joisa S. , Rao C. V. S. , Daniel Raju , Jha Sameer K. , Shukla B. K. , Praveenlal E. V. , Raulji V. , Rajpal R. , Atrey P. K. , Nagora U. , Manchanda R. , Ramaiya N. , Chowdhuri M. B. , Jha R. , Saxena Y. C. , Pal R.
Published: May 2021

Controlling and mitigating plasma disruptions are a matter of serious concern for tokamak operation since they can cause serious damage to the machine. Dedicated experiments on disruption mitigation have been carried out in ADITYA (R = 75 cm, a = 25 cm), an Ohmically heated circular limiter tokamak. A rapid growth of magneto hydrodynamic (MHD) modes is found to be the major cause of disruptions in ADITYA tokamak. Stimulated disruptions induced by hydrogen gas puffing are successfully mitigated through stabilization of these MHD modes by applying a biased-electrode placed inside the last-closed flux surface prior to the gas injection. However, as biased electrodes cannot be placed inside the plasma in bigger tokamaks, the application of ion-cyclotron waves (ICWs) prior to disruption has been successfully attempted to mitigate disruptions through stabilization of MHD modes in ADITYA tokamak. The amplitude of MHD modes (m/n = 3/1, 2/1) is significantly reduced upon the application of ICW prior to disruption, and the stimulated disruptions are successfully mitigated by preventing the growth and overlapping of these MHD modes. These experimental results demonstrate that MHD driven disruptions may be mitigated due to stabilization of m = 2 modes by ponderomotive force of the IC waves.
Repeated plasma current induced by potential fluctuation in atmospheric pressure non-thermal-equilibrium plasma jet
Authors: Yambe Kiyoyuki , Kuramoto Naoya , Izumi Koichi
Published: May 2021

When a plasma irradiates a metal object, a plasma current flows. Plasma currents in the forward and reverse directions, flowing from a powered electrode, for plasma generation, to the metal object, are repeatedly generated. The first plasma current is generated by the applied voltage of the powered electrode. The metal object onto which the plasma flows is charged by the plasma, and the potential of the metal object increases. The potential of the powered electrode follows the time variation of the applied voltage from the AC power supply. Consequently, when the potential time fluctuation of the powered electrode and the potential of the metal object are balanced, a plasma current in the reverse direction is generated. Because the residual charge on the metal object is determined by the dynamic pressure balance due to the potential time fluctuation between the powered electrode and the metal object, the plasma charge flowing in the reverse direction of the electrode can be determined.
Turbulent energy transfer into zonal flows from the weak to the strong flow shear regime in the stellarator TJ-K
Authors: Ullmann T. , Schmid B. , Manz P. , Tovar G. E. M. , Ramisch M.
Published: May 2021

The transition from low to high confinement in fusion experiments is accompanied by a reduction of turbulence in the strong shear regime. This work investigates the influence of the background shearing rate on the energy transfer between turbulence and zonal flows, which can serve as a loss channel of kinetic energy, in the different shear regimes using the k−ε model. To this end, plasma biasing is used to control the flow shear, which is categorized in terms of measured turbulent lifetime. The shearing rate scaling of Reynolds stress and zonal flow production is analyzed. A linear dependency of the Reynolds stress and a quadratic dependency of the energy transfer on the shearing rate are found. This is accompanied by a redistribution of the spectral power toward the zonal flow. The increase in relative zonal power is even higher beyond the transition to the strong shear regime.
Coupling of ethanolamine ammonia-lyase protein and solvent dynamics characterized by the temperature-dependence of EPR spin probe mobility and dielectric permittivity
Authors: Ionescu Alina , Li Wei , Nforneh Benjamen , Warncke Kurt
Published: May 2021

Electron paramagnetic resonance (EPR) spectroscopy is used to address the remarkable persistence of the native Arrhenius dependence of the 2-aminopropanol substrate radical rearrangement reaction in B12-dependent ethanolamine ammonia-lyase (EAL) from Salmonella typhimurium from physiological to cryogenic (220 K) temperatures. Two-component TEMPOL spin probe mobility in the presence of 10 mM (0.08% v/v) 2-aminopropanol over 200–265 K demonstrates characteristic concentric aqueous-cosolvent mesodomain and protein-associated domain (PAD, hydration layer) solvent phases around EAL in the frozen solution. The mesodomain formed by the relatively small amount of 2-aminopropanol is highly confined, as shown by an elevated temperature for the order–disorder transition (ODT) in the PAD (230–235 K) and large activation energy for TEMPOL rotation. Addition of 2% v/v dimethylsulfoxide expands the mesodomain, partially relieves PAD confinement, and leads to an ODT at 205–210 K. The ODT is also manifested as a deviation of the temperature-dependence of the EPR amplitude of cob(II)alamin and the substrate radical, bound in the enzyme active site, from Curie law behavior. This is attributed to an increase in sample dielectric permittivity above the ODT at the microwave frequency of 9.5 GHz. The relatively high frequency dielectric response indicates an origin in coupled protein surface group–water fluctuations of the Johari–Goldstein β type that span spatial scales of ∼0.1–10 Å on temporal scales of 10−10–10−7 s. The orthogonal EPR spin probe rotational mobility and solvent dielectric measurements characterize features of EAL protein–solvent dynamical coupling and reveal that excess substrate acts as a fluidizing cryosolvent to enable native enzyme reactivity at cryogenic temperatures.
Triangles and electrostatic ion traps
Authors: Giorgadze G. , Khimshiashvili G.
Published: May 2021

We consider the equilibrium points of the electrostatic potential of three mutually repelling point charges with Coulomb interaction placed at the vertices of a given triangle T. It is proven that for each point P inside the triangle T, there exists a unique collection of positive point charges, called stationary charges for P in T, such that P is a critical point of the electrostatic potential of these point charges placed at vertices of T in a fixed order. Explicit formulas for stationary charges are given, which are used to investigate the existence and geometry of stable equilibria arising in this setting. In particular, symbolic computations and computer experiments reveal that for an isosceles triangle T, the set S(T) of points P that are stable equilibria of their stationary charges is a non-empty open set containing the incenter of a triangle T. For a regular triangle, using symbolic computations, it appears possible to verify that the formulas for stationary charges define a stable mapping in the sense of Whitney having a deltoid caustic with three ordinary cusps. An interpretation of our results in terms of electrostatic ion traps is also given, and several plausible conjectures are presented.
Successive strain hardening mechanisms induced by transformation induced plasticity in Fe60Mn20Co10Cr10 high entropy alloys
Authors: Gao Tianyu , Jin Xi , Qiao Junwei , Yang Huijun , Zhang Yong , Wu Yucheng
Published: May 2021

Transformation induced plasticity (TRIP) effect in high entropy alloys (HEAs) overcomes the strength–ductility “trade-off” and leads to the synchronous improvement of strength and ductility. In this work, we studied a TRIP Fe60Mn20Co10Cr10 HEA with a dual-phase structure consisting of face-centered cubic matrix and hexagonal close-packed (HCP) martensite. By warm-rolling and subsequent annealing, three samples with different recrystallization conditions and HCP phase volume fractions were obtained. The alloys exhibit a good combination of ultimate tensile strength (∼700–900 MPa) and elongation (∼45%–55%), representing sustainable strain hardening behavior over extended deformation regime. To reveal the deformation mechanism of the present TRIP HEA, the method to determine the stacking fault energy (SFE) via a regular solution model was discussed, and the SFE of Fe60Mn20Co10Cr10 alloys at 300 K was estimated as 15.3 mJ/m2. The low SFE promotes the formation and overlapping of stacking faults via dislocation interaction, which provides nucleation sites of HCP martensite and further contributes to the striking strain hardening capacity upon tension.
Research on the test method of substituting bulk current injection for electromagnetic radiation in the coupling channel of parallel double lines
Authors: Sun Jiangning , Pan Xiaodong , Lu Xinfu , Wan Haojiang , Wei Guanghui
Published: May 2021

Radiation effect test cannot be performed in large-scale space simulations of a strong field electromagnetic environment, and existing BCI (bulk current injection) technology employed for nonlinear system tests is subjected to its limitation. Given this, the present study analyzes the equivalent radiation test method of BCI in the parallel double-line coupling channel. To be specific, the response analysis models of the EUT (equipment under test) under the radiation condition and the injection condition are developed with the nonlinear response system as the EUT. In addition, the corresponding equivalent relationship is derived between the voltage of the injection excitation source and the radiation field intensity. Subsequently, the condition and the test method to substitute BCI for radiation are proposed and experimentally verified. As revealed from the research results, specific to nonlinear response systems, the BCI method proposed here can be accurately equated with the radiation effect test of the EUT. It is noteworthy that the maximum test error only reaches 3.62 dB, capable of satisfying the actual requirements of the project.
Development of an immersed boundary-multiphase lattice Boltzmann flux solver with high density ratio for contact line dynamics
Authors: Chen Guo-Qing , Zhang A-Man , Liu Nian-Nian , Wang Yan
Published: May 2021

Interaction between a two-phase fluid and a structure involving contact line dynamics is a common phenomenon. In this paper, we aim to develop a fluid–solid coupling model that can study contact line dynamics in the case of a high density ratio between the two fluids. The fluids are treated using a multiphase lattice Boltzmann flux solver (MLBFS) that uses the cell-centered finite volume method to obtain macroscopic flow variables, and the interface fluxes are reconstructed locally by the standard lattice Boltzmann method (LBM) solutions. This approach retains the advantages of the original LBM while being more flexible in handling nonuniform grids and external force terms. The immersed boundary method (IBM) is an effective method for processing structural information, and here, the implicit boundary-condition-enforced IBM is used to accurately satisfy the Dirichlet boundary condition (no-slip boundary). Moreover, the Neumann boundary condition is deemed to represent the contribution from the structure boundary flux and is incorporated into the IB-MLBFS. The developed IB-MLBFS is verified by several test cases, including contact line motion of a two-phase fluid along a circular cylinder and droplet spreading on a flat plate, where both equilibrium results and dynamic process are correctly reproduced for different density ratios and wettability conditions. Furthermore, based on the IB-MLBFS established here, the contact line dynamics of a two-phase fluid between two square cylinders or two circular cylinders is studied. The effects of distance, structure size, and wettability on the interface state and the contact angle are studied in detail. The robustness of the proposed model is verified.
Tunable Schottky contact in the graphene/WSe2(1−x)O2x heterostructure by asymmetric O doping
Authors: Zhang Rui , Hao Guoqiang , Ye Xiaojun , Zhang Wenjing , Li Hongbo
Published: May 2021

Tuning the electrical transport properties of a nanoelectronic device with a p-type Schottky contact remains a grand challenge. To solve this issue, we explore the effectiveness of asymmetric O doping on performance improvements of the graphene/WSe2(1−x)O2x (Gr/WSe2(1−x)O2x) heterostructure using first-principles calculations. The results show that graphene and the WSe2(1−x)O2x monolayer could form a stable van der Walls interface. Further, the controlled asymmetric O doping at different positions and concentrations regulates the electronic properties of the Gr/WSe2(1−x)O2x heterostructure in terms of the type and the height of the Schottky barrier. It is found that a transformation of a Schottky contact from an n-type to p-type is realized by changing the position of the O dopant from inside to outside, and a high Schottky barrier height of 0.72 eV in the undoped Gr/WSe2 heterostructure can be reduced to 0.06 and 0.09 eV for the O doing inside and outside the interface, respectively. In addition, when the O doping concentration increases to 67% both inside and outside of the interface, the Ohmic contacts are observed. Last, the controllable Schottky contact in the Gr/WSe2(1−x)O2x heterostructure is induced by the charge redistribution of the interface, which is caused by the shift of the Fermi level. This work may provide a promising method to improve the electronic performance of the Gr/WSe2 nano field effect transistors.
The tungsten carbide–carbon monoxide–tungsten buffer and its use for synthesizing iron-bearing silicates in muffle furnaces
Authors: Dobson David P.
Published: May 2021

A new “solid-state” oxygen buffering reaction (WC-COW), WC + 1/2O2 ⇌ CO + W, is presented. At atmospheric pressure, the oxygen fugacity in equilibrium with this buffer is approximated in the range of 600–1200 °C by logfO2=1.53−21008TK±0.13bar. A simple method for maintaining oxygen fugacity in standard muffle furnaces using this buffer in off-the-shelf ceramic crucibles is described. The utility of the experimental arrangement in controlling oxygen fugacity during solid-state synthesis of iron-bearing silicates is demonstrated by rapid synthesis of fayalite, Fe2SiO4, from oxide starting mixtures at 1050 °C.
Correlation between Raman spectra and color of tungsten trioxide (WO3) thermally evaporated from a tungsten filament
Authors: Escalante Germán , López Roberto , Demesa Francisco Noé , Villa-Sánchez Gerardo , Castrejón-Sánchez Víctor Hugo , Vivaldo de la Cruz Israel
Published: May 2021

The color exhibited by tungsten trioxide (WO3) can be associated with both its stoichiometry and crystallinity. Correlation between the color exhibited by WO3 powders and their purity and crystalline properties is reported in this paper. The WO3 powders were deposited by evaporation of tungsten trioxide from the surface of a tungsten filament. The WO3 powders exhibited three different shades of blue: navy, royal, and sky. The color of the WO3 powders changed to white after thermal treatment at 500 °C for 30 min in an ambient atmosphere. Raman analyses showed that transition from amorphous to crystalline WO3 started when the powders exhibited navy-blue color and ended when WO3 powders exhibited a white color. Scanning electron microscopy analysis showed particle agglomeration characteristics in all WO3 powders, even after they were thermally treated. The mechanism of deposition of WO3 from the tungsten filament was suggested to be governed by thermal evaporation of tungsten trioxide from the surface of the oxidized tungsten filament.
A superconducting coplanar waveguide ring resonator as quantum bus for circuit quantum electrodynamics
Authors: Huang Wenhui , Zhou Yuxuan , Tao Ziyu , Zhang Libo , Liu Song , Chen Yuanzhen , Yan Tongxing , Yu Dapeng
Published: May 2021

We introduce a superconducting coplanar waveguide, in the form of a ring resonator, as a quantum bus for circuit quantum electrodynamics (circuit QED). Due to its unique symmetry, the amplitude of the electromagnetic field inside is uniform along the resonator, which in principle leads to a location independent coupling between qubits and the resonator. For an experimental demonstration, we designed and fabricated a ring resonator capacitively coupled to two tunable Xmon superconducting qubits. We showed that nearly identical coupling was achieved between individual qubits and the resonator. In addition, the resonator was also used as a high quality quantum bus for generating Bell states between the qubits with a fidelity of F=98.6%, although an interference effect must be included for understanding the effective coupling between the two qubits. Our results suggest that ring resonators can be a useful addition to the toolbox of circuit QED.
On Koopman mode decomposition and tensor component analysis
Authors: Redman William T.
Published: May 2021

Koopman mode decomposition and tensor component analysis [also known as CANDECOMP (canonical decomposition)/PARAFAC (parallel factorization)] are two popular approaches of decomposing high dimensional datasets into modes that capture the most relevant features and/or dynamics. Despite their similar goal, the two methods are largely used by different scientific communities and are formulated in distinct mathematical languages. We examine the two together and show that, under certain conditions on the data, the theoretical decomposition given by the tensor component analysis is the same as that given by Koopman mode decomposition. This provides a “bridge” with which the two communities should be able to more effectively communicate. Our work provides new possibilities for algorithmic approaches to Koopman mode decomposition and tensor component analysis and offers a principled way in which to compare the two methods. Additionally, it builds upon a growing body of work showing that dynamical systems theory and Koopman operator theory, in particular, can be useful for problems that have historically made use of optimization theory.
Finite-amplitude RF heating rates for magnetized electrons in neutral plasma
Authors: Guthrie John M. , Roberts Jacob L.
Published: May 2021

A theoretical model is developed and evaluated using a Vlasov–Poisson treatment to calculate radio frequency (RF) electric field heating rates for magnetized electrons in neutral plasma when the magnetic and electric field directions are colinear and when the RF is of sufficiently high frequency. This calculation reduces to the theory for magnetized longitudinal AC conductivity introduced by Oberman and Shure [Phys. Fluids 6, 834–838 (1963)] in the low-amplitude limit when the electron oscillation velocity is much less than the thermal velocity. For electron coupling strengths Γ = 0.15–0.015 and RF fields accessible to ultracold neutral plasma experiments, the model predicts mild variations in heating rate of order unity across magnetization strengths spanning orders of magnitude. The predicted effect of including a Bhatnagar-Gross-Krook-type collisional relaxation term in the Vlasov equation reduces the heating rate by 5% or less across magnetizations.
Effect of B and O doping on the electronic structure and quantum capacitance of carbon nitride monolayers using first-principles calculations
Authors: Chen Xiaojie , Xu Wenxian , Jin Jiaming , Wang Peixian , Song Bin , He Pimo
Published: May 2021

The structural, electronic, and capacitance properties of B- or O-doped carbon nitride monolayers were systematically investigated using first-principles calculations. Different single-atom substitutions (i.e., B or O dopant on a Cx or Ny substitution site) were considered for this work. The substitution site plays an important role in regulating the stability and electronic structure of carbon nitride monolayers. B or O doping could make carbon nitride monolayers produce large local density of states near Fermi level contributed mainly from the hybridization of the 2p states of C, N, and the doped atom (B or O), thus significantly improving conductivity, quantum capacitance, and surface charge density of the structures. The results show that the quantum capacitances of the B-doped carbon nitride monolayers are much greater than those of the B-doped graphene monolayers. Furthermore, B-doped C3N at the C1 site, B-doped tg-C3N4 at the N2 site, and O-doped tg-C3N4 at the N1 site are strongly recommended as the electrodes in symmetrical supercapacitors, while the other doped components could also be used as cathode or anode materials in asymmetrical supercapacitors. The findings of this study suggest that doped carbon nitride structures could be considered as promising electrode materials for supercapacitors.
Bi-directional impulse chaos control in crystal growth
Authors: Zhou Zi-Xuan , Ren Hai-Peng , Grebogi Celso
Published: May 2021

Mono-silicon crystals, free of defects, are essential for the integrated circuit industry. Chaotic swing in the flexible shaft rotating-lifting (FSRL) system of the mono-silicon crystal puller causes harm to the quality of the crystal and must be suppressed in the crystal growth procedure. From the control system viewpoint, the constraints of the FSRL system can be summarized as not having measurable state variables for state feedback control, and only one parameter is available to be manipulated, namely, the rotation speed. From the application side, an additional constraint is that the control should affect the crystallization physical growth process as little as possible. These constraints make the chaos suppression in the FSRL system a challenging task. In this work, the analytical periodic solution of the swing in the FSRL system is derived using perturbation analysis. A bi-directional impulse control method is then proposed for suppressing chaos. This control method does not alter the average rotation speed. It is thus optimum regarding the crystallization process as compared with the single direction impulse control. The effectiveness and the robustness of the proposed chaos control method to parameter uncertainties are validated by the simulations.
Dynamics of hole injection from p-GaN drain of a hybrid drain embedded GIT
Authors: Sun Jinming , Haeberlen Oliver , Ostermaier Clemens , Prechtl Gerhard , Tadikonda Ramakrishna , Persson Eric , Garg Reenu , Imam Mohamed , Khalil Sameh , Charles Alain
Published: May 2021

The addition of a p-GaN drain to a conventional gate-injection transistor (GIT), forming the so-called hybrid drain embedded GIT, is crucial in the suppression of the dynamic Rdson. The DC leakage due to hole injection is limited to around 10 nA/mm at 600 V (25 °C). However, an injected hole current of several amperes (W = 210 mm) has been observed during the hard switching event. To reconcile this difference over 6 orders of magnitude, a TCAD study is carried out to understand the dynamics of the hole injection and what leads to the difference between the static and the transient current. According to the scenario played out by the present simulation model, the high concentration of carbon, intentionally doped to control the vertical leakage, plays a crucial role in limiting the hole injection current to its DC level, while under fast switching, the hole injection current can be very high due to a lag in response on the part of the carbon trap.
Temperature-dependent Raman studies and thermal conductivity of direct CVD grown non-van der Waals layered Bi2O2Se
Authors: Hossain Md Tarik , Giri P. K.
Published: May 2021

Layered materials with the van der Waals gap have been extensively studied due to their fascinating properties. However, non-van der Waals type layered Bi2O2Se exhibiting remarkable properties is challenging to grow due to the weak electrostatic interaction among layers. Herein, we present chemical vapor deposition (CVD) growth of an air-stable ultrathin Bi2O2Se semiconductor with high structural and chemical uniformity. By tuning the growth temperature, we obtained ultra-smooth single crystals of few-layer Bi2O2Se (LBOS) on mica and quartz substrates, as confirmed from x-ray diffraction, micro-Raman, and high-resolution TEM analyses. Furthermore, a low-temperature Raman study has been conducted to better realize phonon dispersion in the as-grown LBOS in the temperature range 78–293 K. It is observed that the A1g phonon mode frequency of LBOS varies linearly with the temperature with a first-order temperature coefficient (α) of −0.017 87 ± 0.0011 cm−1 K−1. The broadening of the Raman spectral linewidth with temperature has been explained based on the phonon decay, and a phonon lifetime of 2.08 ps is found for LBOS at absolute zero temperature. Finally, the in-plane thermal conductivity of LBOS is estimated by a non-contact measurement technique in a relatively straightforward way. Taking advantage of the excitation power dependency of the A1g mode and using the first-order temperature coefficient, the in-plane thermal conductivity of LBOS is estimated to be ∼1.6 W/mK. Our results pave the way for large-area CVD growth of LBOS on arbitrary substrates and developing insights into electron–phonon and phonon–phonon interactions in non-van der Waals 2D materials.