Free Mode Research Articles

Photon self-energy at all temperatures and densities in all of phase space

In an isotropic background comprised of free charges, the transverse and longitudinal modes of the photon acquire large corrections to their dispersion relations, described by the in-medium photon self-energy. Previous work has developed simple approximations that describe the propagation of on-shell photons in plasmas of varying temperatures and densities. However, off-shell excitations can also receive large medium-induced corrections, and the on-shell approximations have often been used in an effort to capture these effects. In this work we show that the off-shell self-energy can be qualitatively very different than the on-shell case. We develop analytic approximations that are accurate everywhere in phase space, especially in classical and degenerate plasmas. From these, we recover the on-shell expressions in the appropriate limit. Our expressions also reproduce the well-known Lindhard response function from solid-state physics for the longitudinal mode.

Free vibrational mode shapes and frequencies of sandwich folded plates standing on folded foundation and structured by auxetic honeycomb core and FG-GPLRC coating layers

In this article, for the first time, the free vibration and modal shapes of sandwich folded plate with honeycomb core are studied. The current article investigates the free vibrational mode shapes and frequencies of sandwich folded plate made of auxetic honeycomb core and graphene platelet-reinforced functionally graded composite (FG-GPLRC) coating layers which standing on the normal-shear folded supports. The structures are supported by normal-shear folded supports. The negative Poisson’s ratio exhibited by honeycomb materials results in distinct physical and mechanical properties, profoundly impacting the behavior of structures constructed from this material. While structures with basic shapes like rectangular, circular, and spherical configurations find limited applications across various industries, the versatility of folded structures makes them highly suitable for a wide range of industrial applications, given their more complex geometries. Dynamic equations are formulated within the framework of the first-order shear deformation theory (FSDT) for each flat section of the folded plate. The continuous equality conditions for displacements, rotations, and stresses at the junction edges of the two flat sections are rigorously satisfied. To effectively solve these equations, a robust numerical technique known as the generalized differential quadrature method (GDQM) is employed specifically tailored for the 2D analysis of folded plates. Furthermore, the study investigates the influence of various parameters, including material properties and geometry, on the frequencies and mode shapes of the folded structures, shedding light on the intricate interplay between these factors in shaping the dynamic response of the structures.

Temperature-dependent vibrational energy relaxation of hydrogen-bonded and free OD groups at the air-water interface.

Water interfaces play a crucial role in regulating interactions and energy flow. Vibrational sum-frequency generation (vSFG) spectroscopy provides structural and dynamic information on water molecules at interfaces. It has revealed, for instance, the presence of the hydrogen-bonded and free OH groups at the air-water interface. Here, using temperature-dependent, time-resolved vSFG, we focus on the vibrational energy relaxation dynamics of interfacial heavy water (D2O). We reveal that while the relaxation timescale for hydrogen-bonded OD stretch modes is temperature-independent, the lifetime of the free OD stretch mode decreases with increasing temperature. Our data, supported by simulations, suggest that both intramolecular energy transfer and rotational reorientation mechanisms jointly contribute to the energy relaxation process of the free OD, with temperature influencing these mechanisms differently.

Dynamic optimization design of thin plate structure based on surrogate model

Abstract To enhance dynamic optimization efficiency in traditional thin plate structures, surrogate models are integrated for structural dynamic size optimization, reducing dependence on high-precision finite element simulations. This paper focuses on optimizing the aluminum alloy sheet as the subject of research. The parameters of the specimen are optimized through sensitivity analysis, based on the comparison between the free mode Finite Element Analysis (FEA) and Experimental Modal Analysis (EMA) results. The modified specimen undergoes validation under a four-edge clamped boundary condition. Subsequently, random vibration analysis is conducted to determine the root mean square (RMS) value of the acceleration response. Employing surrogate model technology, four models are constructed using parametric modeling and experimental design methods. These models are then compared for their fitting effectiveness. The results indicate that the RBF model exhibits the highest accuracy in fitting each response, effectively replacing dynamic simulation. Finally, the RBF combined with the NSGA-II method, optimizes the specimen’s structural size, resulting in a 21.6% reduction in mass and an 18.60% decrease in acceleration response. These outcomes demonstrate satisfactory optimization results, ensuring accuracy while enhancing the dynamic characteristics of the specimen structure. This research offers valuable insights for related engineering applications.

Dynamics analysis and collaborative optimization of vehicle steering mechanism

In order to improve the dynamic response characteristics of the steering mechanism, a research scheme for increasing the natural frequency based on lightweight design was proposed. Based on the finite element method and the collaborative optimization method, the modal characteristics and harmonic response characteristics of the model were studied and analyzed to verify the strength and stiffness performance of the optimized structure. The modal shapes between the free mode and the constrained mode were compared and analyzed. With the second-order natural frequency as the optimization objective, the response surface function of the equivalent stiffness was constructed. Through optimization calculation, the design variables that satisfy the constraint conditions can be obtained. The results show that the optimized structure can increase the second-order natural frequency by 14.4 % on the premise of reducing the mass by 5.2 %, effectively avoiding the excitation frequency of the engine.

AlN/ScAlN composite films-based spurious free A1 mode lamb wave resonator with adjustable effective electromechanical coupling coefficient

AlN/ScAlN composite films-based spurious free A1 mode lamb wave resonator with adjustable effective electromechanical coupling coefficient

About the improvement in Mars Polar Motion determination from radio tracking of two landers

The polar motion of Mars is defined as the movement of the rotation axis with respect to a body-fixed frame tied to the crust of the planet. It is composed of forced motion at annual and sub-annual frequencies caused by the seasonal mass redistribution, formation of the polar ice caps and angular momentum variations of the atmosphere, and of the free mode called the Chandler wobble.Radio-tracking data from landers offers the most suitable means to measure the rotation of Mars, including its polar motion. The latter, however, has not yet been achieved using lander data alone. In this study, we assess the uncertainties associated with Mars polar motion estimation using Direct-To-Earth Doppler, range and Same-Beam Interferometry (SBI) observables between multiple landers on the surface of Mars. We evaluate the improvement enabled by combining data from multiple landers with respect to one-lander scenarios, and identify the optimal mission architectures for polar motion estimation by considering the influence of respective mission parameters on the estimation uncertainty. In particular, we consider the effects of absolute and relative locations of the landers and of mission scheduling. We re-evaluate the possibility of estimating the polar motion using data from landers in proximity to the equator, and apply our considerations to simulated data consistent in number and accuracy with that collected by past Martian missions. We notice and explain a strong longitude dependence of the formal errors when the polar motion parameters are estimated concurrently with the seasonal spin variation parameters, making it impossible to properly determine all components of polar motion with a single lander regardless of its location. However, the use of two or more landers in optimal locations with respect to each other eliminates those limitations. We evaluate the influence of latitudinal and longitudinal separation on polar motion determination in such cases. In particular, we are able to determine polar motion well even in cases where the longitudes of the two landers make determination from each single lander impossible.

Sound source localization based on microphone array mounted on unmanned aerial vehicles

Abstract Microphone array installed on unmanned aerial vehicles (UAV) can be used for acoustic detection in scenes, such as detecting noise sources in factories or monitoring corona in power grids. However, using acoustic sensors on UAV has great challenges. The motor rotation of UAV and the non-stationary noise generated by propeller make it difficult for microphone array to obtain useful information for sound source localization. In order to reduce self-noise, an improved least mean square (LMS) adaptive filtering algorithm is proposed. Combining filtering algorithm and multiple signal classification (MUSIC) algorithm to locate the sound source, the noise spectrum characteristics of UAV in outdoor free flight mode are analyzed. The microphone array is used to collect data and realize sound source localization in low Signal-to-Noise Ratio (SNR) environment. The simulation and experimental results show that the algorithm improves the robustness of the sound source localization algorithm in low SNR environment, and realizes the real-time localization of the target sound source during the flight of UAV with microphone array.

Voluntary and Adaptive Control Strategy for Ankle Rehabilitation Robot

The control strategy of rehabilitation robots should not only adapt to patients with different levels of motor function but also encourage patients to participate voluntarily in rehabilitation training. However, existing control strategies usually consider only one of these aspects. This study proposes a voluntary and adaptive control strategy that solves both questions. Firstly, the controller switched to the corresponding working modes (including challenge, free, assistant, and robot-dominant modes) based on the trajectory tracking error of human-robot cooperative movement. To encourage patient participation, a musculoskeletal model was used to estimate the patient's active torque. The robot's output torque was designed as the product of the active torque and a coefficient, with the coefficient adaptively changing according to the working mode. Experiments were conducted on two healthy subjects and four hemiplegic patients using an ankle rehabilitation robot. The results showed that this controller not only provided adaptive the robot's output torque based on the movement performance of patients but also encouraged patients to complete movement tasks themselves. Therefore, the control strategy has high application value in the field of rehabilitation.

Testing of wood shear modulus based on cantilevered square plate torsional vibration method

ABSTRACT The application of the energy method has proposed a dynamic testing method for the shear modulus in two mutually perpendicular directions on the principal surface of wood using a cantilevered square plate torsional vibration method. In the study, this method was applied to measure the shear modulus of larch wood in the LT and TL directions, as well as the longitudinal and transverse shear modulus of Laminated Veneer Lumber (LVL) sheets. The validity of the results was confirmed through experimental verification using the asymmetric four-point bending beam method, the free plate torsional vibration method, and the free square plate torsional mode method. Simulation calculations of the principal shear modulus for six species of trees with width-to-thickness ratios ranging from 10 to 25 were also conducted using this method. The conclusions drawn suggest that a width-to-thickness ratio of 15 for the cantilevered square plate provides sufficient accuracy for testing the principal shear modulus of wood. Furthermore, the difference in shear modulus between two mutually perpendicular directions on the principal surface of wood is dependent on the width-to-thickness ratio of the cantilevered square plate, indicating that this method outperforms other dynamic methods for testing wood shear modulus.

Aging suppression in Multistrip Multigap Resistive Plate Chambers for high counting rate experiments

A long term operation of Multi-Strip Multi-Gap Resistive Plate Chambers (MSMGRPC) with gas mixtures based on C2H2F4 and SF6 leads to aging effects observed as depositions on the surface of the resistive electrodes, especially in the region of the spacers used for defining the gas gaps between the resistive electrodes. The observed higher noise rate and dark current has a negative impact on the performance of the chamber and leads to an increase of the data volume in a free running readout mode operation. MSMGRPC prototypes designed with a direct gas flow through the gas gaps and minimization of the number of spacers in the active area were developed as mitigation solution. Three new prototypes of different granularities were assembled using fishing line as spacers and investigated for aging effects. Although a significant reduction in the dark current and dark counting rate was evidenced, noise rate localized around the fishing line spacers, even though reduced, still remains. In this paper, a new generation of direct flow chambers based on discrete spacers is presented. The results of their aging investigations show that, even at lower gas flows, the aging effects become negligible.

Vibrational and Dissipative Characteristic Measurement of Solid-state Wave Gyroscope Resonators: Algorithms Based on the Identification of Free Oscillation Equations

The article describes the methodological basis for constructing computational circuits of different complexity degrees and different purposes for solving a wide range of industrial and laboratory problems to measure angular irregularity of vibrational-dissipative resonatorcharacteristics of integrating solid-state wave gyroscopes. The main method to solve such problems is the identification of the coefficients of the differential equations of quartz hemispherical resonator state in the mode of its free oscillations. The resonator oscillation equations both in the fixed measuring axes and in the moving axes of standing waves were chosen as the equations of state. After reduction to slow variables, only slowly changing amplitudeequations are left for identification problems. In all the described circuits, it is assumed that the information signals for the solved identification tasks are formed in a measuring device similar to the standard gyroscope device. These algorithms make it possible to measure the vibrational and dissipative characteristics of resonators with different degrees of completeness and directionality for different standard initial requirements to themeasurement accuracy and experimental modes, which makes it possible to reduce the measurement time and labor intensity of the established set of production control operations. Among the tasks to be solved for the free run-down mode of the resonator wave pattern are the following: angular irregularity measurement of the gyroscope resonator dissipative properties under conditions of low and significant residual frequency difference; angular non-uniformity measurement of gyroscope resonator vibrational properties (its different frequency); simultaneous measurement of resonator oscillatory and dissipative characteristics for fixed and special rotating gyroscope modes. The detailed processing of the computational schemes for the implementation of these algorithms is focused on their practical application for various tasks of production operational control. At the same time, the choice of the most suitable computational algorithm from the considered options depends on the conditions, requirements and specifics of measurements.

Direct design of ground-state probabilistic logic using many-body interactions for probabilistic computing

In this work, an innovative design model aimed at enhancing the efficacy of ground-state probabilistic logic with a binary energy landscape (GSPL-BEL) is presented. This model enables the direct conversion of conventional CMOS-based logic circuits into corresponding probabilistic graphical representations based on a given truth table. Compared to the conventional approach of solving the configuration of Ising model-basic probabilistic gates through linear programming, our model directly provides configuration parameters with embedded many-body interactions. For larger-scale probabilistic logic circuits, the GSPL-BEL model can fully utilize the dimensions of many-body interactions, achieving minimal node overhead while ensuring the simplest binary energy landscape and circumventing additional logic synthesis steps. To validate its effectiveness, hardware implementations of probabilistic logic gates were conducted. Probabilistic bits were introduced as Ising cells, and cascaded conventional XNOR gates along with passive resistor networks were precisely designed to realize many-body interactions. HSPICE circuit simulation results demonstrate that the probabilistic logic circuits designed based on this model can successfully operate in free, forward, and reverse modes, exhibiting the simplest binary probability distributions. For a 2-bit × 2-bit integer factorizer involving many-body interactions, compared to the logic synthesis approach, the GSPL-BEL model significantly reduces the number of consumed nodes, the solution space (in the free-run mode), and the number of energy levels from 12, 4096, and 9–8, 256, and 2, respectively. Our findings demonstrate the significant potential of the GSPL-BEL model in optimizing the structure and performance of probabilistic logic circuits, offering a new robust tool for the design and implementation of future probabilistic computing systems.

Assessing Pedagogical Innovations: Empowering Excellence with OSVE in Undergraduate MBBS Students at Rai Medical College,Sargodha

Objectives: To explores the perception & effectiveness of objectively structured viva examinations (OSVE) in 3rd year MBBS students as compared to routine general viva for future implementation at Rai Medical College, Sargodha. Methodology: This cross-sectional study was performed at Rai Medical College (RMC), Sargodha The total number of participants were 120 third-year MBBS students.Routine objectively structured viva examinations (OSVE) of forensic medicine was conducted. During the OSVE, each student was assigned to specific stations. The students' viewpoints were evaluated before and after the OSVE through a customize structured questionnaire.Categorical variables including the responses strongly agree, agree, neutral, strongly disagree, disagree are presented as frequencies and percentages. Chi square test was used to check the differences in proportions of perception of male and female concerning various aspects of OSVE. Results: This study was comprised of 120 medical students, of which 65(54.16%) and 55(45.93%) were female and male student respectively. Of total participants 39.2 and 25% of students were felt that structured viva format was more convenient than routine unstructured viva. Of total students 47.5 % of students agreed that the allocated time for answering questions in OSVE was appropriate. Concerning encouragement from teacher to give relevant answer during OSVE, 48.3 % and 45.0% of students were strongly disagreed and disagreed respectively rest were agreed or remain neutral. Only19.2 and 23.3% of students were strongly agreed and agreed presence of bias in unstructured oral viva. Most of students were strongly agreed (37.5 %) or agreed (29.2%) for implementation of OSVE for all academic years for all medical subjects. Significant statistical difference was observed in opinions of male and female with respect to encouragement in OSVE from examiner and biasness during unstructured viva with p values0.002 and 0.027, whereas we did not find any significant difference among gender point of views for all other aspects of OSVE. Conclusion: Objectively structured viva examinations, as perceived by the participants, was mostly convenient and bias free mode of assessment compared to traditional unstructured oral viva examination. OSVE should be implemented in all academic years for all subjects.

Analysis and Review of Graphene based Super-Capacitor and its Fast Charging in application of Electric Vehicle

Electric Vehicles are reflected as a significant solution in developing an ecological and carbon free mode of transportation. However, the major encounters for the EVs smooth performances are its high cost, limited range of process and fast battery dreadful conditions. There are several promising strategy with comprehensive optimization techniques can lead to solve out the above-said issues. This paper represents an overview of effective fast charging techniques of EV in graphene based Super capacitor as an Energy storage system (ESS) concerning prolonging life cycle and high charging efficiency of ESS for EVs instead of Battery as an energy storage system. This paper is also dealing with the comparison analysis between the Li-ion based battery as an energy storage system with the Graphene based Super Capacitor as ESS in application of EVs

A generative adversarial network for enhancing over-expansion flow field perception of nozzles with large expansion ratio

Over-expansion flow and separation phenomena exist inside the nozzle during the startup and shutdown of the rocket engine, and the transition between the separation modes is prone to cause significant side loads and jeopardize the safety of the engine. Accurate, comprehensive and prompt nozzle flow field state perception is of great significance to the stable operation of the engine. Here, a generative adversarial network is proposed to reconstruct the internal Mach number and temperature fields for different nozzle pressure ratios and flow separation modes based on the discrete pressure at the nozzle wall. The proposed generative adversarial network employs Wasserstein distance and gradient penalty to improve the problems of gradient vanishing and pattern collapse during discriminator network training. The large expansion ratio nozzle selected was the VOLVO S1 nozzle and numerical simulations were carried out under different nozzle pressure ratio conditions to obtain data for the training of data-driven model. The results indicate that generative adversarial networks can accurately reconstruct restricted shock separation and free shock separation modes under different nozzle pressure ratios based on discrete pressure and temperature measurement points on the nozzle wall, with a relative error of less than 1.2%, and accurately identify important flow field characteristics such as Mach disk, supersonic jet flow, and multiple recirculation regions. The advantages of the generative model in recognizing the strong normal shock Mach disk are compared with those of the supervised learning model. This study lays the foundation for the subsequent study of nozzle side load and structural fatigue life based on three-dimensional flow field.

Research on the Development Trend and Evolution of the Chinese Animation Industry

Although China's animation industry has developed vigorously everywhere, but there has been no period of relative prosperity. On the contrary, China's animation industry has been in a situation of not rising, and the similarities and differences between domestic animation works and animation before and after decades are neither accidental nor coincidental. The animation industry in Europe, the United States, Japan, and other places have been vigorously developed. Their development is not overnight, including the innovative reform of the animation industry and completely free play mode, so that the United States and Japan animation has become the benchmark for the quality of animation works in the world. As a result of this phenomenon, China's animation industry is closely related to the national system, policy, market, and other factors. The reform of the talent training system is an important aspect, and national policy support is also a key link, and the most fundamental is artistic innovation. As a rising star, the animation industry is playing an increasingly important role in the global cultural industry. We should take advantage of the opportunity to develop the animation industry vigorously with Chinese characteristics. We should try our best to eliminate all adverse factors in the development of animation, adapt to the global development trend, quickly form a positive interaction between the government and the industry and the market, creators and audiences, achieve the revitalization of China's animation industry, and challenge high-quality animation from Europe, the United States, Japan, and other foreign countries.

COMPARATION OF PHOTOGRAMMETRY AND TERRESTRIAL LASER SCANNING METHODS FOR EROSION MONITORING IN THE AREA OF DEVIL’S TOWN: PROJECT “DEMONITOR”

<p>Project "Devils’ town Erosion MONITORing - DEMONITOR" involves the monitoring of accessible earth pillars in the area of Devil’s town, by using a combination of several non‐invasive methods. Terrestrial laser scanning (TLS) and photogrammetric imaging with unmanned aircraft (UAV) as a platform showed as great solutions for 3D modeling of this site and erosion monitoring. In this work it is shown that using manual free flight mode for imaging with UAV gave much better results than the missions performed with predefined flight plans. The desired long‐term effect from this research should have a significant part in the overall socioeconomic development of the municipality of Kuršumlija, and the entire Toplica district.</p>

Method for testing the stability of an autoregressive model of the vocal tract and adjusting its parameters

Within the framework of the traditional direction of research in the field of acoustic measurements, an autoregressive model of the vocal tract as a key link in the human speech apparatus is considered. The acute problem of ensuring the stability of the autoregressive model in systems with adaptation of its parameters to the observed speech signal of short duration is pointed out. To overcome this problem, the task was set of testing the stability of the autoregressive model and adjusting its parameters based on the results of this testing. The study is based on the author’s method of formant analysis of vowel sounds of speech through the synthesis of a recursive shaping filter in the free oscillation mode. To solve sated task, a method is proposed for testing the stability and adjusting the parameters of the autoregressive model of the vocal tract based on a two-stage algorithm for its transformation. At the first stage of transformation, the stability of the autoregressive model is tested using the impulse response of the shaping filter. At the second stage, if the stability of the autoregressive model is violated, its impulse response is modified by element-by-element multiplication by a variable exponential value that asymptotically converges to zero. A regular algorithm has been developed for recalculating the modified impulse response into an adjusted vector of autoregressive parameters at the second stage of transformation. Based on the results of experimental testing of the proposed method, it was concluded that guaranteed stability of the autoregressive model of the vocal tract has been achieved with minimal distortion in the frequency domain. The results obtained are useful in the development and modernization of automatic speech recognition systems, digital speech communications, artificial intelligence and other information systems that use data compression and speech coding based on an autoregressive model of the vocal tract in automatic speech signal processing.

Metadynamics approach elucidating the free energy landscape and binding modes of vomicine with virulence factor towards anti-mpox drug discovery

This study targeted MPXV (mpox virus) virulence factor (MPXV_VF) for anti-mpox drug discovery using Strychnos nux-vomicaphytochemicals. Molecular docking showed stronger binding energy of phytochemicals (−7.1–−6.1 kcal/mol) compared to brincidofovir (−5.2–−4.9 kcal/mol). Molecular dynamics simulations authenticated the conformational stability of MPXV_VF-VCN complex. The most potent to inhibit MPXV_VF was VCN that exhibited favourable ADMET profiles comparable to brincidofovir. The metadynamics as a function of distance of Arg85Cα with VCN-C18, and phi Arg85 showed two deepest free energy basins (−129.144 and −109.250 kJ/mol) relative to unbound state. Thus, VCN could be used as main-stream drug candidate for mpox treatment.