Mode Competition Research Articles

Analysis of multimode radiation from 0.4 THz backward wave oscillator

Abstract A terahertz backward wave oscillator (BWO) is a high-power terahertz wave source based on the Cherenkov interaction between an electron beam and a slow backward wave. Excitation of slow wave modes with different mode numbers degrades the performance of BWO due to mode competition. Analyzing the mode spectrum is a difficult challenge to confirm single mode operation. In this study, the excitation of the slow waves in a 0.4 THz cylindrical corrugated waveguide is examined. In the corrugated waveguide, azimuthal modes become slow backward waves with evanescent fields. We found the superposition of the modes with different azimuthal indices has an asymmetric field intensity and the excitation of the superposed modes produces the terahertz radiation with the asymmetric pattern. We conduct a BWO experiment using a 0.4 THz corrugated waveguide. The experimental radiation pattern is obtained and corresponds well to the calculated asymmetric pattern. The symmetry of the radiation can be regarded as an indicator of the mode control.

Hollow cathode discharge instability onset in electric thrusters

Hollow cathodes are an integral part of ion, and Hall thrusters are used for electric propulsion in deep space missions and in commercial communications satellites. Hollow cathodes are known to operate in a quiescent “spot mode” and in a noisy “plume mode” in which plasma instabilities generate erosive energetic ions. The onset of the plume mode in hollow cathodes has been defined historically as when the keeper voltage oscillation values exceed 5 Vpp (peak-to-peak). Using a LaB6 hollow cathode in a vacuum chamber setup that simulates operation in ion and Hall thrusters, a set of emissive and Langmuir probes have been used to investigate the plasma properties associated with plume mode onset as a function of discharge current and gas flow rate. We find that the plume mode onset occurs at even less than 2 Vpp of the keeper voltage for the 5–75 A hollow cathode investigated here and starts at higher gas flow rates than expected from the traditional 5 Vpp metric used by those in the field. Mode competition and coupling between three different instabilities observed in the near-cathode plume affect the overall plasma oscillation levels that are correlated to energetic ion production. We find that the plasma oscillation levels measured by in situ plasma diagnostics are more indicative of the presence of oscillations and the generation of energetic ions than indirect keeper voltage measurements.

Procedura finansowania zadań publicznych realizowanych przez organizacje pozarządowe w trybie art. 19a ustawy o działalności pożytku publicznego i o wolontariacie

The article discusses the procedure for financing public tasks commissioned by the executive bodies of local government in a non-open competition mode, regulated in Art. 19a of the Act on Public Benefit and Volunteering, which is the basic legal act regulating the functioning of non-governmental organizations in Poland. Commissioning the implementation of public tasks may take the form of entrusting the implementation of a public task or supporting the implementation of a public task. The basic form of commissioning public tasks by local government administration bodies is the competition procedure. It allows the principle of competitiveness and transparency of this process to be maintained. However, the legislator provided for the possibility of commissioning the implementation of public tasks also in a non-competition mode. By creating this possibility of commissioning public tasks, it introduced numerous restrictions for this mode, thanks to which this procedure is secondary to the basic form of commissioning public tasks by way of an open competition. The purpose of the discussion here is to analyze the procedure in matters relating to outsourcing the implementation of public tasks to non-governmental organizations by local government administration bodies within the meaning of the above-mentioned Act in a non-competition manner. The article also contains proposals for amending the regulation in question to adapt it to the currently existing socio-economic relations, because this regulation has been in force for over twenty years and requires changes, which results from the previous experience in its application.

Multiwavelength erbium-doped fiber laser using the polarization-hole-burning effect for multichannel acoustic detection.

We propose and demonstrate a novel, to the best of our knowledge, fiber-optic multipoint acoustic detection system based on a multiwavelength erbium-doped fiber (EDF) laser (MWEDFL) using the polarization-hole-burning effect with Fabry-Perot interferometers as the acoustic cavity-loss modulator. A polarization-wavelength-related filter is designed to assign a distinct polarization state to each laser wavelength. By adjusting the polarization state, the polarization-dependent loss and gain of each laser line are tuned to be equal, effectively suppressing the mode competition of EDF and enabling a stable MWEDFL. Each laser line serves as a separate channel for acoustic detection. Theoretical and experimental analyses are conducted to study the transient-response-amplification effect on the acoustic perturbation of the MWEDFL. The results show that the proposed MWEDFL exhibits an amplification effect on the sound-induced cavity-loss modulation, effectively enhancing the sensitivity by 13 dB compared to that obtained using an external-light-source demodulation method. In addition, the MWEDFL based on the PHB effect avoids cross talk between laser channels and can achieve high sensitivity and simultaneous multichannel acoustic detection.

Ultra-high cycle fatigue and ultra-slow crack growth behavior of additively manufactured AlSi7Mg alloy

PurposeThe purpose of this paper is to determine the ultra-high cycle fatigue behavior and ultra-slow crack propagation behavior of selective laser melting (SLM) AlSi7Mg alloy under as-built conditions.Design/methodology/approachConstant amplitude and two-step variable amplitude fatigue tests were carried out using ultrasonic fatigue equipment. The fracture surface of the failure specimen was quantitatively analyzed by scanning electron microscope (SEM).FindingsThe results show that the competition of surface and interior crack initiation modes leads to a duplex S–N curve. Both manufacturing defects (such as the lack of fusion) and inclusions can act as initially fatal fatigue microcracks, and the fatigue sensitivity level decreases with the location, size and type of the maximum defects.Originality/valueThe research results play a certain role in understanding the ultra-high cycle fatigue behavior of additive manufacturing aluminum alloys. It can provide reference for improving the process parameters of SLM technology.

Mode Competition of Low Voltage Backward Wave Oscillator near 500 GHz with Parallel Multi-Beam

Mode Competition of Low Voltage Backward Wave Oscillator near 500 GHz with Parallel Multi-Beam

Tricritical state and quasi-periodicity triggered by the non-linear elasticity in an Upper Convected Maxwell fluid confined between two co-oscillating cylinders about zero-mean

The effects of harmonically co-oscillating the inner and outer cylinders about zero mean rotation in a Taylor–Couette flow are examined numerically using Floquet theory, for the case where the fluid confined between the cylinders obeys the upper convected Maxwell model. Although stability diagrams and mode competition involved in the system were clearly elucidated recently by Hayani Choujaa et al. (2021) in weakly elastic fluids, attention is focused, in this paper, on the dynamic of the system at higher elasticity with emphasis on the nature of the primary bifurcation. In this framework, we are dealing with pure inertio-elastic parametric resonant instabilities where the elastic and inertial mechanisms are considered of the same order of magnitude. It turns out, on the one hand, that the fluid elasticity gives rise, at the onset of instability, to the appearance of a family of new harmonic modes having different axial wavelengths and breaking the spatio-temporal symmetry of the base flow: invariance in the axial direction generating the O(2) symmetry group and a half-period-reflection symmetry in the azimuthal direction generating a spatio-temporal Z2 symmetry group. On the other hand, new quasi-periodic flow emerging in the high frequency limit and other interesting bifurcation phenomena including bi and tricritical states are also among the features induced by the fluid elasticity. Lastly, and in comparison with the Newtonian configuration of this system, the fluid elasticity leads to a total suppression of the non-reversing flow besides emergence of instabilities with lower wavelengths. Such a comparison provides insights into the dynamics of elastic hoop stresses in altering the flow reversal in modulated Taylor–Couette flow.

Consumption network externalities, corporate social responsibility, and conflicting interests: Cournot vs. Bertrand competition

AbstractIn this paper, we will delineate the nexus of consumption network externalities, corporate social responsibility (CSR), and conflicting interest issues under Cournot and Bertrand competition. We find that a stronger degree of network externalities may bring conflicting interests between firms and the consumers, benefiting firms while hurting consumers. The degree of conflicting interests caused by network externalities is consistent in Cournot and Bertrand competition. Furthermore, when firms do CSR activities, the presence of network externalities may alleviate the conflicting interests caused by CSR activities and bring a “win–win” outcome between firms and consumers in two competition modes.

Topological Dissipative Photonics and Topological Insulator Lasers in Synthetic Time‐Frequency Dimensions

AbstractThe study of dissipative systems has attracted great attention, as dissipation engineering has become an important candidate toward manipulating light in classical and quantum ways. Here, the behavior of a topological system is theoretically investigated with purely dissipative couplings in a synthetic time‐frequency space. An imaginary bandstructure is shown, where eigen‐modes experience different eigen‐dissipation rates during the evolution of the system, resulting in mode competition between edge states and bulk modes. Numerical simulations show that distributions associated with edge states can dominate over bulk modes with stable amplification once the pump and saturation mechanisms are taken into consideration, which therefore points to a laser‐like behavior for edge states robust against disorders. This work provides a scheme for manipulating multiple degrees of freedom of light by dissipation engineering, and also proposes a great candidate for topological lasers with dissipative photonics.

Influence of quality factor on operating mode of TM<sub>02</sub> mode relativistic backwave oscillator

<sec>The mode competition in an overmoded relativistic backward wave oscillator is studied through theoretical analysis and three-dimensional particle-in-cell simulation in this work. Based on the quality factor and coupling impedance, the mode selection for a TM<sub>02</sub> mode backward wave oscillator is achieved, and its output power and magnetic field strength are optimized in the simulation.</sec><sec>The quality factor is related to the group velocity and end reflection of each mode. The dispersion curves of some non-axisymmetric modes are very close, and the group velocities are basically equal. Therefore, the end reflection needs considering to distinguish between the quality factors of different modes. In frequency domain simulation, analyzing the quality factor of each mode by using the <i>S</i><sub>11</sub> parameter curve can avoid calculating the end reflection.</sec><sec>The three-dimensional simulation results show that the coupling impedance and quality factor jointly affect the operating mode. When the coupling impedance advantage of the working mode is not obvious, changing the resonant frequency of the high-frequency structure can affect the beam-wave interaction process, thereby changing the excitation mode. When the advantage is obvious, the beam-wave interaction of the excitation mode will not be destroyed by the resonant mode, and other modes of microwave output mainly come from the conversion of the same frequency modes. Due to the constant dispersion curve, the effect of resonance on the mode is essentially the effect of the quality factor on the mode dominated by the end reflection.</sec><sec>The insensitive parameters and the electron beam radius obtained from the simulation are used as the optimal parameters, and the automatic optimization algorithm is used in combination with the two-dimensional simulation to perform multi-objective optimization design in the above device. The final output power of the backward wave oscillator reaches 534 MW, with an efficiency of 23.64%, an increase of 221.7% compared with the efficiency of the original device. The device operating mode remains stable, with a power ratio of TM<sub>02</sub> mode reaching 94.95%.</sec>

Analyzing Wooclap’s competition mode with AI through classroom recordings

Analyzing Wooclap’s competition mode with AI through classroom recordings

Exploration of Teaching and Training Methods for College Volleyball Based on Competition Mode

Exploration of Teaching and Training Methods for College Volleyball Based on Competition Mode

Analysis and Suppression of Mode Competition in a Relativistic Klystron Oscillator

Analysis and Suppression of Mode Competition in a Relativistic Klystron Oscillator

Exploring Inter-Brain Electroencephalogram Patterns for Social Cognitive Assessment During Jigsaw Puzzle Solving.

Social interaction enables the smooth progression of our daily lives. Mounting evidence from recent hyperscanning neuroimaging studies indicates that key components of social behavior can be evaluated using inter-brain oscillations and connectivity. However, mapping out inter-brain networks and developing neurocognitive theories that explain how humans co-create and share information during social interaction remains challenging. In this study, we developed a jigsaw puzzle-solving game with hyperscanning electroencephalography (EEG) signals recorded to investigate inter-brain activities during social interactions involving cooperation and competition. Participants were recruited and paired into dyads to participate in the multiplayer jigsaw puzzle game with 32-channel EEG signals recorded. The corresponding event-related potentials (ERPs), brain oscillations, and inter-brain functional connectivity were analyzed. The results showed different ERP morphologies of P3 patterns in competitive and cooperative contexts, and brain oscillations in the low-frequency band may be an indicator of social cognitive activities. Furthermore, increased inter-brain functional connectivity in the delta, theta, alpha, and beta frequency bands was observed in the competition mode compared to the cooperation mode. By presenting comparable and valid hyperscanning EEG results alongside those of previous studies using traditional paradigms, this study demonstrates the potential of utilizing hyperscanning techniques in real-life game-playing scenarios to quantitatively assess social cognitive interactions involving cooperation and competition. Our approach offers a promising platform with potential applications in the flexible assessment of psychiatric disorders related to social functioning.

Competitiveness of modes of transport in Kazakhstan: influencing factors and rating

This article discusses the competitiveness of various modes of transport in Kazakhstan and provides an assessment of the main factors influencing the choice of transportation modes within the realm of economics. The comprehensive rating system aimed at evaluating the competitiveness of different transportation modes in Kazakhstan. Drawing upon various perspectives and analytical methodologies, this system proves to be a valuable tool for politicians and stakeholders seeking to optimize Kazakhstan transportation system. The primary objective of this study is to examine which of the selected factors has the most significant impact on Kazakhstan's decisions regarding the choice of transportation vehicles. The thorough analysis of key literature sources was carried out and a methodology based on our findings was selected. The methodological approach involves the creation of multi-factor regression models utilizing the EViews10 data analysis software package. The research dataset encompasses data from the Bureau of National Statistics of the Republic of Kazakhstan's Agency for Strategic Planning and Reforms for the years 2013 to 2022. Calculations derived from our research revealed that the selected factors have varying effects on different types of transportation. As a result of this study, it becomes possible to formulate recommendations for state policies in the realm of transportation infrastructure and its implications for economic and social development, with a specific focus on enhancing vehicle capacity. The study's findings are of relevance to transportation companies and governmental entities responsible for managing the transportation system.

Research on Digital Economy Driving High Quality Development of China's Manufacturing Industry

With the profound changes in the global industrial economic situation, the industrial competition pattern is further adjusted, China's original reliance on the "demographic dividend" effect of the manufacturing industry expansion path is facing the challenge of low-end locking and marginalization, the urgent need to cultivate new kinetic energy. Get rid of the inherent low-cost competition and scale expansion mode, promote the digital transformation of the manufacturing industry, are the road to high-quality development of the manufacturing industry under the new development pattern. On the one hand, the digital economy has reconstructed the layout of the manufacturing industry chain in digital space and physical space, effectively unimpeded the domestic macrocycle; on the other hand, the digital economy can promote China's manufacturing industry to the high-end of the value chain, and win a larger profit space and the right to speak for the manufacturing industry to integrate into the international cycle. Therefore, under the new development pattern of internal and external double cycle, digital economy has become the new kinetic energy for the upgrading of China's manufacturing industry. This project combs through the domestic digital economy to drive the high-quality development of the manufacturing industry related literature, summarizes the economy to drive the high-quality development of the manufacturing industry measurement method, organizes the recent years of China's manufacturing industry development related research, consolidates the research foundation and expands the research perspective, constructs the "scale - structure", We construct a four-dimensional analytical framework of "scale-structure" and "circulation-external circulation" for the high-quality development of manufacturing industry, and explore the theoretical mechanism of digitalization-driven high-quality development of manufacturing industry. Through the use of econometric modeling methods to carry out empirical analysis of the digital economy driven manufacturing high quality, according to the empirical results, more scientific formulation of the digital economy driven China's manufacturing industry upgrading countermeasures recommendations.

Governmental Local Investment Fund as a Financial Instrument to Support Urban Investment by the Example of Cities with District Status in the Lodz Voivodeship

The purpose of the article/hypothesis is to present the Government's Local Investment Fund as a financial tool to support municipalities and districts during the COVID-19 pandemic crisis and to provide an assessment of the support received in the context of investment expenditure incurred by cities with district rights in the Lodz Voivodeship.
 Methodology: On the basis of data from the Chancellery of the Prime Minister and the financial reports of the Cities with a District Status, the amount of funding granted from the Government Local Investment Fund was reviewed. Based on data from the Local Data Bank, the basic financial data for three Cities with a District Status from the Lodz Voivodeship in the years 2019–2021 was analysed, i.e. in the context of the use of funds from the Government Local Investment Fund.
 Results of the research: Local government units during the COVID-19 pandemic had an opportunity to obtain financial support from the state budget for the implementation of investment tasks from the Government Local Investment Fund. A total amount of PLN 13 billion was allocated to local governments. The funds were distributed in three rounds using two different qualification methods: algorithm and competition mode. Cities with a District Status under the competition procedure received less support than other local governments, and there were even situations in which they were deprived of this support. The distribution and the amount of support awarded caused a lot of controversy at the same time highlighting a need for changes in the system of local finances.

PELATIHAN PEMBUATAN MEDIA INTERAKTIF MENGGUNAKAN APLIKASI CLASSPOINT UNTUK MENGOPTIMALKAN PEMBELAJARAN DI SEKOLAH DASAR

So far, the use of PowerPoint is only for media presentations or teaching materials that are one-way in nature. Presentations using PowerPoint are commonly used, especially by teachers at SDN 14 Cakranegara. This service seeks to further optimize learning with applications that can be integrated with the use of PowerPoint. The application is called Classpoint which is an interactive media that can load learning material in the form of questions, quizzes, or questions. The types of questions provided by Classpoint which can be accessed for free include multiple choice, short answer, word cloud, slide drawing, image upload with competition mode, and other settings. the methods of implementing the service that will be carried out include presentations by the lecturer team, question, and answer activities and discussions, as well as direct assistance in making Classpoint interactive media. The training at SDN 14 Cakranegara was conducive because the 10 participants were guided by 5 service team members and 2 students so that obstacles could be overcome immediately. The presenters were very communicative and guided step by step and ensured that each participant could go through each step before moving on to the next step. In the training of the five types of Classpoint interactive quiz features such as multiple choice, word clouds, short answers, slide drawings, and image uploads, all of them can be applied.

PELATIHAN PEMBUATAN MEDIA INTERAKTIF MENGGUNAKAN APLIKASI CLASSPOINT UNTUK MENGOPTIMALKAN PEMBELAJARAN DI SEKOLAH DASAR

So far, the use of PowerPoint is only for media presentations or teaching materials that are one-way in nature. Presentations using PowerPoint are commonly used, especially by teachers at SDN 14 Cakranegara. This service seeks to further optimize learning with applications that can be integrated with the use of PowerPoint. The application is called Classpoint which is an interactive media that can load learning material in the form of questions, quizzes, or questions. The types of questions provided by Classpoint which can be accessed for free include multiple choice, short answer, word cloud, slide drawing, image upload with competition mode, and other settings. the methods of implementing the service that will be carried out include presentations by the lecturer team, question, and answer activities and discussions, as well as direct assistance in making Classpoint interactive media. The training at SDN 14 Cakranegara was conducive because the 10 participants were guided by 5 service team members and 2 students so that obstacles could be overcome immediately. The presenters were very communicative and guided step by step and ensured that each participant could go through each step before moving on to the next step. In the training of the five types of Classpoint interactive quiz features such as multiple choice, word clouds, short answers, slide drawings, and image uploads, all of them can be applied.

Generation of cylindrical vector beam pulses by using multi-wavelength EDFL with two-mode fiber filter

A multi-wavelength erbium-doped fiber laser (MW-EDFL) operating in the L-band with cylindrical vector beam outputs is proposed and experimentally investigated. The multi-wavelength lasing is realized by exploiting a two-mode fiber filter (TMFF) as the comb filter and a single-mode fiber spool with 2-km in length to suppress the mode competition. The multi-wavelength combs with channel spacing of 0.36 nm, 0.58 nm, and 1.12 nm are achieved by regulating the interference length of the TMFF, and up to 18 lasing channels are obtained with a wavelength spacing of 0.36 nm. Good long-term stability is manifested within a 100-minute duration, as the maximum peak power fluctuation of 1.96 dB and the maximum wavelength shift of 0.03 nm are measured. By adjusting the polarization controller associated with the two-mode long-period grating as a high-efficiency mode converter, radially and azimuthally polarized cylindrical vector beams of high purity are thus generated.