Barrier Shape Research Articles

Study on noise barrier shape for reducing Shinkansen noise using scale model experiment

Since Shinkansen viaducts are aging, a large-scale renovation project has been planned. In this project, aged noise barriers of various shapes are scheduled to be removed and replaced. After replacing the noise barriers, further noise reduction is required. Therefore, it is desirable to verify the relationship between shapes of noise barriers and noise reduction effects. Against this background, the scale model experiments were conducted in anechoic chamber, focusing on the heights, the edge shapes of noise barrier and the differences in the area where sound absorbing materials were applied to the noise barrier. In these experiments, noise levels outside a viaduct were evaluated when the conditions of the noise barrier were changed. As one of the results, it is shown that applying sound absorbing material as large an area as possible is effective in reducing noise, regardless of the differences of edge shapes. Based on the experiments, it is thought that noise barriers with simple shape for easy maintenance can be realized by effective use of sound absorbing materials for replacing the aged noise barriers.

평균 토크 향상을 위한 단절권 매입형 영구자석 동기전동기의 회전자 배리어 형상 최적 설계

평균 토크 향상을 위한 단절권 매입형 영구자석 동기전동기의 회전자 배리어 형상 최적 설계

Escape of an active ring from an attractive surface: Behaving like a self-propelled Brownian particle.

Escape of active agents from metastable states is of great interest in statistical and biological physics. In this paper, we investigate the escape of a flexible active ring, composed of active Brownian particles, from a flat attractive surface using Brownian dynamics simulations. To systematically explore the effects of activity, persistence time, and the shape of attractive potentials, we calculate escape time τ_{e} and effective temperature T_{eff}. We observe two distinct escape mechanisms: Kramers-like thermal activation at small persistence times, where ln(τ_{e})∼1/(k_{B}T_{eff}), and the maximal force problem at large persistence time, where τ_{e} is determined by persistence time. The escape time explicitly depends on the shape of the potential barrier at high activity and large persistence time. Moreover, when the propulsion force is biased along the ring's contour, escape becomes more difficult and is primarily driven by thermal noise. Our findings highlight that, despite its intricate configuration, the active ring can be effectively modeled as a self-propelled Brownian particle when studying its escape from a smooth surface.

The effect of Cu-doping to the DLC interlayer on the temperature dependent current-conduction mechanisms and barrier shape of the Schottky devices

The objective of this study is to determine the temperature and voltage-dependent current conduction mechanisms (CCMs) of the Al/Cu-doped DLC/p-Si Schottky device. It is aimed to obtain extensive and detailed data by current-voltage (I–V) measurements taken with 0.3 V voltage steps in the ±4 V voltage range, at 30 K intervals from 80 K to 410 K. Firstly, an examination of the semi-logarithmic I–V curve revealed that the low temperature (LTs, 80 K–170 K), medium temperature (MTs, 200 K–290 K) and high temperature (HTs, 320 K–410 K) regions should be examined separately. The basic parameters of the Schottky device such as the ideality factor (n), reverse saturation current (Io) and zero-biasing potential barrier height (ΦBo) were obtained separately for LTs, MTs and HTs by the Thermionic Emission (TE) theory. The results obtained show that the device deviates from ideality, especially in LTs and HTs, and the n values decrease with increasing temperature, while the ΦBo values increase. The analysis of the presence of other CTMs in the Schottky device revealed that Field Emission (FE) and Thermionic Field Emission (TFE) were effective in LTs and MTs, while FE was effective in HTs. Since it is thought that quantum mechanical CTMs cannot be the cause of such a deviation from ideality due to the interface layer thickness, the existence of Gaussian Distribution originating from lateral barrier inhomogeneity was investigated. As a result, it is concluded that the Multiple Gaussian Distribution (MGD) is dominant in the possible CTMs of the Schottky device.

Matter-wave interferometry based on barrier beam splitters

In this letter, we explore the use of barriers as coherent beam splitters for the construction of matter-wave interferometers. The effect of barrier shape and width, wave-packet width, and interatomic interaction on the interference signal is comprehensively investigated. Numerical simulations demonstrate the feasibility of constructing an atom interferometer utilizing deep-cooled Bose-Einstein condensates with barrier beam splitters. Such an interferometer exhibits the capability to measure acceleration with an accuracy of up to 10−8 g within a single measurement cycle.

Motivators and Barriers to COVID-19 Vaccination Intentions Across U.S. County-Level Barriers in the COVID-19 Vaccine Coverage Index.

County-level barriers (sociodemographic barriers, limited healthcare system resources, healthcare accessibility barriers, irregular healthcare seeking behaviors, low vaccination history) may impact individuals' reasons for receiving the COVID-19 vaccine. This study linked data from REACH-US (Race-Related Experiences Associated with COVID-19 and Health in the United States), a nationally representative, online survey of 5475 adults living in the U.S (January-March 2021) to county-level barriers in the COVID-19 Vaccine Coverage Index. County-level vaccination barriers were measured using the COVID-19 Vaccine Coverage Index. Participants reported why they would or would not receive the COVID-19 vaccine in an open-ended item and their responses were coded using thematic analysis. Descriptive statistics and chi-square tests assessed whether reasons for COVID-19 vaccination intentions varied by county-level barriers and whether these distributions varied across racial/ethnic groups. Thematic analysis revealed twelve themes in participants' reasons why they would or would not receive the COVID-19 vaccine. Themes of societal responsibility (9.8% versus 7.7%), desire to return to normal (8.1% versus 4.7%), and trust in science/healthcare/government (7.7% versus 5.1%) were more frequently reported in counties with low/medium barriers (versus high/very high) (p-values < 0.05). Concerns of COVID-19 vaccine side effects/safety/development (25.3% versus 27.9%) and concerns of access/costs/availability/convenience (1.9% versus 3.6%) were less frequently reported in counties with low/medium barriers (versushigh/very high) (p-values < 0.05). Trends in the prevalence of these themes varied across racial/ethnic groups (p-values < 0.05). Future pandemic responses should consider potential ways county-level barriers shape reasons for COVID-19 vaccination.

The transition to a circular economy: different paths for international and non-international micro-manufacturing firms

This article examines how environmental awareness, stakeholder pressure, circular economy orientation and internal barriers influence circular economy practices in international and non-international micro-firms. For this, we utilised fuzzy set qualitative comparative analysis (fsQCA) using data from 128 micro firms operating in different manufacturing industries in Estonia. Three paths were identified for explaining circular economy practices in internationally operating micro-firms and two paths for explaining it in micro-firms that do not operate internationally. Our results show that understanding the impact of the four before-mentioned aspects can be beneficial for engaging in circular economy efforts in both international and non-international micro-firms. The intricate five pathways (three for international and two for non-international) through which environmental awareness, stakeholder pressure, circular economy orientation, and internal barriers shape circular economy practices in micro-firms, challenging conventional understandings and offering nuanced insights for effective engagement in sustainable business practices. Based on the findings, theoretical and practical implications of this study and directions for future research are discussed.

Influence of barrier shape on impact dynamics of debris flow entraining a boulder onto rigid barriers

Influence of barrier shape on impact dynamics of debris flow entraining a boulder onto rigid barriers

Navigating the roadmap to meta-governance adoption

Purpose This study aims to investigate citizens' adoption intention towards meta-government (metaverse-based government) by proposing a dual-perspective technology acceptance model. Design/methodology/approach The validity of the proposed model was established by gathering and analysing 533 responses using structural equation modelling (SEM). Findings The study findings underscore the importance of perceptions of ease of use and usefulness in fostering the intention to adopt meta-government. However, perceived cyber risk and switching costs negatively impact these perceptions. On the contrary, herd behaviour and perceived immersion positively influence perceptions of ease of use and usefulness. Originality/value This study significantly contributes to the existing literature by offering valuable insights into the factors that influence citizens' adoption of meta-government. It introduces a novel perspective on the primary factors (both enablers and barriers) shaping citizens' adoption intention of meta-government. These insights serve as a foundation for scholars, governments and policymakers to develop effective strategies for promoting meta-government adoption.

Body Fit With a Pouching System With Concave Contour for People With an Outward Peristomal Body Profile: Effects on Leakage, Wear Time, and Quality of Life: A Randomized Controlled Cross-Over Trial.

The purpose of the study was to investigate the fit of a two-piece pouching system with a concave-shaped skin barrier on people with an outward peristomal body profile and its effect on leakage, wear time, and quality of life (QoL) related to using an ostomy product. Randomized, controlled, open-label, cross-over trial. The sample comprised 53 subjects with outward peristomal body profiles and problems with leakage of ostomy effluent from their pouching system. Participants were randomized to the concave two-piece pouching system or a comparator (two-piece pouching system with a flat skin barrier) for 3 weeks. Subjects were then crossed over to the opposite skin barrier for an additional 3 weeks. The study was conducted in Denmark, Norway, Germany, and the Netherlands; data were collected in multiple ambulatory clinics or during home visits. The primary end point was the ability of the skin barrier to fit body contours; secondary outcomes were leakage of effluent from the pouching system, wear time, and QoL related to using an ostomy product via the validated Ostomy-Q questionnaire. Primary comparisons between concave and comparator pouching systems were evaluated using proportional odds models and mixed models taking test period into account. Analysis included randomized subjects who had been exposed to at least one product and with information on at least one end point (full-analysis-set, n =52). The concave pouching system provided a better fit to body contours than the comparator (P<.001) and reduced the degree of leakage underneath the skin barrier (LS mean difference=-1.84, 95% CI -3.31 to -0.37; P =.016). Participants experienced fewer episodes of leakage outside the skin barrier when using concave versus comparator pouching system (13.0% vs. 26.7%, respectively). Participants reported significant improvements in QoL (LS mean difference=14.3; 95% CI 9.4 to 19.2; P <.001). No significant difference in wear time between skin barrier shapes was reported. Study findings indicate that a pouching system with a concave skin barrier achieved a better body fit on people with an outward peristomal body profile and resulted in fewer leakage incidents and higher QoL compared to using a pouching system with a flat skin barrier.

Design and shape optimization of interior permanent magnet synchronous machine based on hybrid cores

By designing stator teeth using grain-oriented sheets (GO) and other parts still with non-grain-oriented sheets (NGO), the electromagnetic performance of the interior permanent magnet synchronous machine (GO-IPMSM) can be improved greatly. As the stator core of the designed GO-IPMSM is a hybrid core that is composed of two different silicon sheets, both the electromagnetic and mechanical performances are affected by the stator joint shape between GO and NGO sheets. Meanwhile, with the adoption of GO, the torque ripple of GO-IPMSM is increased though the average torque is increased as well. For reducing the torque ripple, optimizing the rotor barrier shape is an effective way. In this paper, the piecewise linear interpolation method is employed for establishing the stator joint shape between GO and NGO sheets, and the polynomial method is proposed to establish the rotor barrier shape. Through the analysis, it can be seen that the stator joint shape plays a strong role in affecting the mechanical performance of the GO-IPMSM, while the effect on the electromagnetic performance is weak. The genetic algorithm is used to optimize the rotor barrier shape for achieving high average torque and low torque ripple. Lastly, a quick and accurate efficiency map calculation method based on the Kriging model is proposed for GO-IPMSM with less finite element method (FEM) samples are required.

A spin-injected ferroelectric tunnel junction based on spin-dependent screening theory

In this work, spin transport in ferroelectric tunnel junctions with composite barriers and magnetic electrodes is investigated theoretically using spin-dependent screening theory. The shape of the insulator barrier and the electronic structure of the ferromagnetic electrode inevitably affect the spin transport properties. Interestingly, we find that when the Fermi level approaches the bottom of the minority-spin band of the electrode, an approximately ±100% bidirectional spin-filtering effect can be realized due to the included exchange potential with an appropriate electronic band structure of electrodes. Additionally, electrically induced magnetic reconstruction would occur on the electrode surface due to spin-dependent band bending. Our study significantly deepens the current understanding of spin-dependent screening on metal surfaces and at metal/ferroelectric interfaces and provides a feasible method for achieving the interface magnetoelectric effect.

Multi-Gaussian distribution of barrier height in diamond-like carbon interfacial-layered Schottky devices

Pieces of information about the physical and electronic properties of diamond-like carbon (DLC) interfacial-layered Schottky devices are crucial because DLC is known for its durability against harsh conditions such as high voltage, high temperature, and radiative environments. Therefore, this study focused on determining some critical properties of DCL interlayered Schottky devices, such as current-conduction mechanisms (CCMs) and the shape of the barrier height of the device. Some graphics, such as n-ΦB0vs T, ΦB0vs n, ΦB0vs q/2kT, 1/n−1vs q/2kT, and ln(I0/T2-(qσs)/2k2T2vs kT/q were obtained from the temperature-dependent current-voltage (I–V-T) data to determine the shape of the barrier height (BH) and to understand CCMs of this MIS-type device. Obtained results revealed that the device exhibited different behaviours in three different temperature regions: 80–170 K, 200–290 K and 320–410 K, which were called Low Temperatures (LTs), Moderate Temperatures (MTs) and High Temperatures (HTs), respectively. It was also observed that all these graphs exhibited linear behaviour separately for these three temperature regions. Therefore, these results showed that the barrier shape of this DLC interlayered Schottky device is not homogeneous, and it has a Multi-Gaussian distribution due to three different linear behaviours. On the other hand, in addition to the Thermionic Emission (TE) mechanism, it was also understood that Field Emission (FE) and Thermionic Field Emission (TFE) mechanisms, known as Quantum Mechanical Tunnelling (QMT) mechanisms, were effective current conduction mechanisms, especially at low and moderate temperatures for this device.

Tungsten sputtering coefficients by light impurities of plasma

Calculations of the tungsten sputtering coefficients (the divertor material in the ITER tokamak) by He, Be, N, O – impurity atoms in the plasma – were carried out at collision energy of 0.010–100 keV using the Monte–Carlo method. To calculate the trajectory of the incident particle, pair potentials obtained within the framework of density functional theory were used. These potentials were corrected for the parameters of the potential well obtained from spectroscopic measurements. The target consisted of tungsten randomly oriented crystals the size of one lattice constant. Next, the trajectories of the recoil particles were calculated using many-particle potentials calculated using density functional theory. Thermal vibrations of target atoms were taken into account. The vibration amplitude was taken to be 0.05 Å, which corresponded to room temperature. The strong dependence of the results on the shape of the surface potential barrier is shown and the results are presented for two limiting cases of the surface state: a flat surface, when a planar surface potential barrier is realized, and a surface consisting of cones, when a spherical potential barrier occurs. In the experiment, the surface has some roughness, which depends on the experimental conditions. It is shown that the experimental results lie between the limiting cases we considered. Information was obtained on the average energy of sputtered atoms and angular distributions, necessary for calculating the entry of impurities into the tokamak plasma.

Educators’ understandings of digital classroom tools and datafication: perceptions from higher education faculty

Research has shown that critical data literacies development for educators is seldom a core component of most campus conversations about datafication, even as extractive, datafied systems become pervasive throughout the higher education sector. This article outlines findings from an international, qualitative, Comparative Case Study (CCS) of university professionals teaching online during the COVID-19 pandemic. It overviews beliefs and barriers shaping educators’ responses to datafication and focuses specifically on their perceptions of faculty development opportunities related to digital classroom tools and to datafication more broadly. The article presents insights into how faculty understands higher education’s contemporary datafied infrastructure and highlights participants’ voices about faculty professional development and critical data literacies. Based on our findings, we recommend formal faculty development and broader professional learning conversations as a means of enhancing faculty awareness and agency within the higher education sector.

Utilization of a Genetic Algorithm to Identify Optimal Geometric Shapes for a Seismic Protective Barrier

The utilization of seismic barriers for protection against the hazardous impact of natural or technogenic waves is an extremely promising emerging technology to secure buildings, structures and entire areas against earthquake-generated seismic waves, high-speed-transport-induced vibrations, etc. The current research is targeted at studying the effect of seismic-barrier shape on the reduction of seismic-wave magnitudes within the protected region. The analytical solution of Lamb’s problem was used to verify the adopted numerical approach. It was demonstrated that the addition of complementary geometric features to a simple barrier shape provides the possibility of significantly increasing the resulting seismic protection. A simple genetic algorithm was employed to evaluate the nontrivial but extremely effective geometry of the seismic barrier. The developed approach can be used in various problems requiring optimization of non-parameterizable geometric shapes. The applicability of genetic algorithms and other generative algorithms to discover optimal (or close to optimal) geometric configurations for the essentially multiscale problems of the interaction of mechanical waves with inclusions is discussed.

Thermopower in Underpotential Deposition-Based Molecular Junctions.

Underpotential deposition (UPD) is an intriguing means for tailoring the interfacial electronic structure of an adsorbate at a substrate. Here we investigate the impact of UPD on thermoelectricity occurring in molecular tunnel junctions based on alkyl self-assembled monolayers (SAMs). We observed noticeable enhancements in the Seebeck coefficient of alkanoic acid and alkanethiol monolayers, by up to 2- and 4-fold, respectively, upon replacement of a conventional Au electrode with an analogous bimetallic electrode, Cu UPD on Au. Quantum transport calculations indicated that the increased Seebeck coefficients are due to the UPD-induced changes in the shape or position of transmission resonances corresponding to gateway orbitals, which depend on the choice of the anchor group. Our work unveils UPD as a potent means for altering the shape of the tunneling energy barrier at the molecule-electrode contact of alkyl SAM-based junctions and hence enhancing thermoelectric performance.

Mover structure optimization and performance improvement for halbach consequent-pole PM synchronous linear motors with flux barrier

Aiming at the problems of large thrust ripple, low thrust density and magnetic leakage in the structure of Halbach consequent-pole PM synchronous linear motor, this paper proposes a flux barrier Halbach Consequent-Pole PM Synchronous Linear Motors (BHCP-PMSLM) by using the combination of unequal height PMs and air flux barrier. Firstly, after analyzing the structural magnetic leakage by the magnetic circuit method, the new motor structure proposed by adding an air flux barrier is used to suppress the magnetic leakage and to determine the structural shape of the air flux barrier. Secondly, the GA-ELM-GA algorithm was used to optimize the structural parameters of the motor with the optimization objectives of increasing thrust and reducing thrust ripple, the optimum motor structure parameters are obtained. Then, calculation and comparison of the electromagnetic characteristics of the new structure with three conventional PM synchronous linear motors with non-salient (NS-PMSLM) and Halbach consequent-pole (HCP-PMSLM). From the comparison results, the proposed structure has advantages, so the prototype was machined and experimented. The experimental results show that the optimization algorithm is effective, and the new structure increases the PM utilization by 41.1% and 7.4%, the thrust density by 5.3% and 12.1%, and the thrust fluctuation by 21% less than HCP-PMLSM compared to the conventional non-salient poles and Halbach consequent-pole.

A structural equation modeling of customer attitudes towards residential solar initiatives in Jordan

Photovoltaic (PV) systems have gained global significance as a sustainable and renewable energy resource, playing a pivotal role in mitigating climate change and meeting growing energy demands. Like many other nations, Jordan recognizes the potential of PV systems and has been actively pursuing their adoption across various sectors, particularly in the residential sector. This paper aims to investigate the factors influencing residential customers' perceptions of PV systems and their intentions to adopt these systems in Jordan by identifying key determinants of perception and adoption and developing a comprehensive Structural Equation Model (SEM) to quantify the relationships between identified factors and their effect on the intention to adopt residential PV systems. A theoretical model was developed to achieve the study's objectives, employing confirmatory factor analysis and structural equation modeling. Data for this study was collected through a comprehensive survey targeting the residential segment. The findings indicate that social, technological, governmental, and financial factors positively and statistically significantly impact residential customers' perceptions of PV systems, fostering their intention to embrace this technology. Surprisingly, the environmental factor was deemed insignificant in influencing residential customers' decision-making processes. This research offers valuable insights to various stakeholders, including PV contractors, consultants, governmental entities, policy, and decision-makers. By understanding the key drivers and barriers shaping residential PV adoption, stakeholders can devise more effective strategies to promote sustainable energy practices, foster economic growth, and contribute to the global transition towards cleaner energy sources.

Influence of Flux Barrier Shape and Mechanical Constraints on Field-Weakening Performance in Double-Layer Interior Permanent Magnet Machines

Influence of Flux Barrier Shape and Mechanical Constraints on Field-Weakening Performance in Double-Layer Interior Permanent Magnet Machines