Gap Distribution Research Articles

Electromagnetic and Mechanical Analysis and Measurements of Interior Permanent Magnet Motors Based on Equivalent Magnetic Circuit Method

This paper is about the magnetic field analysis of an interior permanent magnet motor (IPM motor) by using the equivalent magnetic circuit method (EMC method), which requires a small amount of computation time compared with the finite element method (FEM). IPM motors have a specific shape of rotor in which the permanent magnets are embedded. Therefore, in the bridge region, the magnetic saturation is generated due to the shape of the permanent magnet, which affects the magnetic flux density distribution in the air gap and the characteristics of the IPM motor. Thus, to design an IPM motor, the magnetic saturation effects should be considered along with the rotor shape. In addition, because the rotor of the IPM rotates at a high speed directly in connection with the load, the stress generated from the rotor must be stably distributed. Consequently, according to the rotor shape characteristics of the IPM, the stress is concentrated in the thin bridge region during high-speed rotation. When the stress generated in the bridge region exceeds the yield stress of the rotor iron core material, the bridge part is destroyed. Therefore, it is important to analyze the stress that occurs in the rotor during high-speed rotation in the rotor design stage of the IPM. In this study, we analyzed the magnetic field characteristics of an IPM motor using its equivalent magnetic circuit while considering the magnetic saturation in the bridge region. The stability of the rotor was determined by presenting a safety factor based on the maximum stress generated at the rotor for each speed. We derived the stator natural frequency to evaluate the resonance possibility between the electrical frequency and the stator natural frequency. Finally, the validity of the constructed equivalent magnetic circuit was verified by comparing the results with those obtained via the FEM analysis and experiments.

Birds on a wire

We investigate the occupancy statistics of birds on a wire. Birds land one by one on a wire and rest where they land. Whenever a newly arriving bird lands within a fixed distance of already resting birds, these resting birds immediately fly away. We determine the steady-state occupancy of the wire, the distribution of gaps between neighboring birds, and other basic statistical features of this process. We briefly discuss conjectures for corresponding observables in higher dimensions.

Tunable quantum gaps to decouple carrier and phonon transport leading to high-performance thermoelectrics

Thermoelectrics enable direct heat-to-electricity transformation, but their performance has so far been restricted by the closely coupled carrier and phonon transport. Here, we demonstrate that the quantum gaps, a class of planar defects characterized by nano-sized potential wells, can decouple carrier and phonon transport by selectively scattering phonons while allowing carriers to pass effectively. We choose the van der Waals gap in GeTe-based materials as a representative example of the quantum gap to illustrate the decoupling mechanism. The nano-sized potential well of the quantum gap in GeTe-based materials is directly visualized by in situ electron holography. Moreover, a more diffused distribution of quantum gaps results in further reduction of lattice thermal conductivity, which leads to a peak ZT of 2.6 at 673 K and an average ZT of 1.6 (323–723 K) in a GeTe system. The quantum gap can also be engineered into other thermoelectrics, which provides a general method for boosting their thermoelectric performance.

Dual-functional hierarchical mechanical metamaterial for vibration insulation and energy absorption

In this study, the vibration isolation characteristics and crushing behaviors of novel hierarchical mechanical metamaterials are investigated. Numerical analyses are carried out for a class of mechanical metamaterials with different hierarchical configurations. The effects of the hierarchical configurations on the band gap distributions and energy absorption efficiency are carefully studied. The results indicate that the hierarchical configuration has remarkable potential in broadening the band gap and improving energy-absorbing efficiency. Moreover, the configuration (S3) with the best performance of vibration isolation and energy absorption among the proposed metamaterials is determined. The parameter analysis on S3 is further performed to analyze the effects of structural parameters on the band gap characteristics and crushing performance. Finally, multi-objective optimization is employed to seek optimal structural parameters of S3 for enhancing the gap-midgap ratio and the specific energy absorption, simultaneously. This study provides effective guidance for designing mechanical metamaterials with excellent vibration isolation capacity and energy absorption efficiency.

Gaps in the screening process for women diagnosed with cervical cancer in four diverse US health care settings.

Potential care gaps in the cervical cancer screening process among women diagnosed with cervical cancer in an era with increased human papillomavirus (HPV) testing have not been extensively evaluated. Women diagnosed with cervical cancer between ages 21 and 65 at four study sites between 2010 and 2014 were included. Screening histories were ascertained from 0.5 to 4 years prior to cervical cancer diagnosis. We identified potential care gaps in the screening history for each woman and classified them into one of three mutually exclusive types: lack of a screening test, screening test failure, and diagnostic/treatment care gap. Distributions of care gaps were tabulated by stage, histology, and study site. Multivariable nominal logistic regression was used to examine the associations between demographic and cancer characteristics and type of care gap. Of 499 women evaluated, 46% lacked a screening test in the time window examined, 31% experienced a screening test failure, and 22% experienced a diagnostic/treatment care gap. More than half of the women with advanced cancer and squamous cell carcinoma lacked a screening test compared to 31% and 24% of women with localized cancer and adenocarcinoma, respectively. Women aged 21-29 at diagnosis were more likely to experience screening test failure and diagnostic/treatment care gap, while those aged 50-65 were more likely to lack a screening test, compared to women aged 30-39. Our findings demonstrate a continuing need to develop interventions targeting unscreened and under-screened women and improve detection and diagnosis of adenocarcinoma in women undergoing cervical cancer screening and diagnostic follow-up.

Analysing the real-world fuel and energy consumption of conventional and electric cars in Europe

The transport sector constitutes one of the main sources of greenhouse gas emissions in the European Union. Although the literature is rich in studies assessing the factors influencing energy consumption in real world driving, few analyse the divergence between certified and real-world consumption on a fleet level and annual temporal resolution. The present work builds on the findings of previous studies to provide a complete simulation-based approach for fleet-level projections in real-world scenarios. A tailored simulation framework for fleet-wide analysis has been updated and validated extensively for current vehicle configurations. In addition to modelling, the analysis used data describing real-world conditions and vehicle characteristics representative of the European passenger car fleet and operation profile. Validation demonstrates good accuracy in simulating the vehicle measured consumption values with a near-zero mean error when simulating laboratory and on-road measurements. The impact of the certification procedure was quantified at 6% for both the combustion engine and battery electric vehicles. The influence of real-world factors such as traffic, ambient temperature and cabin air conditioning was quantified, and the results show a greater energy impact in the cold than in warm conditions. Different operating conditions were simulated to investigate the model’s capacity to estimate the distribution of the average sales-weighted gap in energy consumption between officially reported CO2 values and the real-world ones. The study focuses on three scenarios: average European conditions, the best and worst case for assessing the extremes, and a Monte Carlo-based scenario to determine the impact of warm and cold periods. Results show average gap values of 13.5% (best case) and 34.5% (worst case) for conventional vehicles and −4.5% (best case) and 23.9% (worst case) for battery electric ones. Warm and cold weather conditions result in 5.5 and 7.5% increases for conventional and hybrids and 7.5 and 15% for electrics, respectively.

Numerical investigation of the effect of clothing air gap distribution and environmental air speed on dry heat transfer underneath clothing

With a great advantage of presenting physical phenomenon in a three-dimensional vision, the technology of computational fluid dynamics was utilized in the current study for simulating and revealing heat transfer in the air gap/layer between human body and clothing. Five clothing configurations including one with realistic heterogeneous air layer and four simplified ones with homogeneous air layers with air gap thickness (AGT) varying between 4 and 16.34 mm were built. All clothing configurations were simulated under environmental air speeds of 0.2–2.5 m/s. It was found the thermal plume, airflow through clothing openings and pathway at armhole have resulted in an uneven distribution of heat transfer underneath clothing, even for clothing with homogeneous air layers. Simply averaging AGT blurs the heterogeneity of heat transfer over the whole body. The threshold of AGT for arising free convection in the air gap is within 12–16.34 mm at the air speed of 0.2 m/s and 8–12 mm at 2.5 m/s, indicating a substantial influence of environmental airflow on thermal flow in the air gap. Besides, increase of air speed would enhance local heat exchange by entering the air gap through clothing openings, except at the arms, where the heat flux fluctuates due to the direction of airflow in sleeves changing from upwards to downwards. Results of the current study have offered a comprehensive insight into the heat transfer in the air gap and can contribute to improving the accuracy of analytical human – clothing – environment models in clothing thermal engineering.

Cosmic Reionization on Computers: Physical Origin of Long Dark Gaps in Quasar Absorption Spectra

I explore the properties of “dark gaps”—regions in quasar absorption spectra without significant transmission—with several simulations from the Cosmic Reionization On Computers (CROC) project. The CROC simulations in the largest available boxes (120 cMpc) come close to matching both the distribution of mean opacities and the frequency of dark gaps, but alas not in the same model: the run that matches the mean opacities fails to contain enough dark gaps and vice versa. Nevertheless, the run that matches the dark gap distributions serves as a counterexample to claims in the literature that the dark gap statistics requires a late end to reionization—in that run reionization ends at z = 6.7 (likely too early). While multiple factors contribute to the frequency of large dark gaps in the simulations, the primary factor that controls the overall shape of the dark gap distribution is the ionization level in voids—the lowest-density regions produce the highest transmission spikes that terminate long gaps. As the result, the dark gap distribution correlates strongly with the fraction of the spectrum above the gap detection threshold and the observed distribution is matched by the simulation in which this fraction is 2%. Hence, the gap distribution by itself does not constrain the timing of reionization, although it may do so in combination with the distribution of mean opacities.

Experimental Study and Simulation Analysis of Slurry Filling Process of Shield Tail Synchronous Grouting

Based on the inadequacy of groundwater pressure and other factors on interstitial pressure and slurry filling rate during synchronous grouting by groundwater action, a scaled-down simulation was carried out and the applicability of the simulation was verified by model tests based on the shield tunnel project of Metro Line 12 under Longzi Lake. The results show that during the synchronous grouting process, the pressure in the slurry filling area mainly depends on the grouting pressure, and the pressure in the gap increases with the increase of grouting pressure; the pressure distribution in the gap in the unfilled area is mainly controlled by the groundwater pressure, and the pressure in the gap is positively related to the groundwater pressure. After the slurry completely fills the gap, the overall pressure distribution in the shield tail gap is more uniform. The slurry filling rate decreases with increasing groundwater pressure and increases with increasing grouting pressure; the effects of changing slurry density and slurry viscosity on the pressure distribution in the interstitial space and the slurry filling rate in the shield tail are not significant. The degree of influence of each factor on the slurry filling rate was in the following order: grouting pressure > groundwater pressure > slurry density > slurry viscosity. The work carried out is a guide to the optimization of synchronous grouting process and parameter design in shield tunnels.

Contributions from ultraperipheral collisions to the forward rapidity gap distribution in pPb collisions at the CERN Large Hadron Collider at sNN=8.16 TeV

In this Letter, we consider strong and electromagnetic (ultraperipheral) mechanisms in proton-nucleus coherent diffraction at the CERN Large Hadron Collider. We explicitly demonstrate the dominance of the latter and explain the CMS data on the forward rapidity gap distribution in $p\mathrm{Pb}$ collisions at $\sqrt{{s}_{NN}}=8.16$ TeV. In particular, we provide simple estimates, which give a good, semiquantitative description of both magnitude and shape of the $\mathrm{\ensuremath{\Delta}}{\ensuremath{\eta}}^{F}$ distribution in the Pomeron-proton topology. We also make predictions for the proton-oxygen run.

Parameter Optimization and Experimental Study on Tool-Vibration-Assisted Pulsed Electrochemical Machining of γ-TiAl TNM Blades

Electrochemical machining (ECM) is one of the main methods for manufacturing gamma-titanium aluminum (γ-TiAl) alloy blades of new-type aero-engines. Tool-vibration-assisted pulsed electrochemical machining (VPECM) is an important method to improve the manufacturing accuracy. In order to determine the influence of processing parameters on the VPECM quality of γ-TiAl TNM alloys, multi-field simulations with different parameter combinations of peak voltage, feed rate, duty cycle, and tool vibration frequency were carried out. The influence of bubble rate and temperature increase on the conductivity distribution in the machining gap under different parameter combinations was analyzed. Then, orthogonal experiments with the above four processing parameters were carried out. The experimental results of surface roughness, replication accuracy, and average current density in the pulse width were interpreted by a grey relational analysis, and the best parameter combination was determined. Finally, four blade-shaped γ-TiAl TNM alloy specimens were processed by using the optimized parameter combination, which had good replication accuracy and surface quality.

An Efficient Air-Gap Flux Density Analysis Method for the Design of Induction Machines

The magnetic field distribution in the air gap is of great importance in the design of rotary machines. In this article, an efficient analytical method is presented, which is capable of plotting the air-gap flux density waveform of induction machines (IMs) less time-consuming than the finite element method (FEM) does. The proposed method, based on the product of the current linkage waveform and the permeance waveform, utilizes the calculations of the steady-state equivalent circuit to ensure the accuracy and an equivalent air-gap reluctance model to take into account both the slot opening effect and the rotor movement. The method is tested on a general IM with different load cases and different design parameters, and the results are compared to the FEM calculations. It can be concluded that the proposed analytical method is an efficient option in the motor design to investigate the influence of the parameters on the flux density distribution.

Analysis on the Income Tax Compliance Behavior of Muzaki at Lazismu Sragen

Introduction to The Problem: Zakat as a deduction of taxable income has become an issue that has attracted the attention of the public economy. The most obvious thing is that the low realization of zakat collection and tax ratios affect the welfare gap (distribution function) and public services received by the citizens (allocation function). On an extreme scale, non-compliance with zakat and tax may threaten social cohesion and legal authority. Purpose/Objective Study: This study aims to find out how zakat regulation as a deduction of taxable income affects muzaki's behavior to comply or not comply with tax obligations. Design/Methodology/Approach: The research design is empirical legal research with qualitative analysis. The primary source builds on focus group discussions (FGDs). Otherwise, secondary sources are collected through a literature study of primary, secondary, and tertiary legal materials. Findings: Zakat as a deduction of taxable income affects muzaki's behavior to comply with tax obligations. The zakat scheme as a deduction of taxable income greatly influences muzaki's behavior within the level of tax compliance, specifically the level of resistance to tax because the system is considered oppressive, to move up to the level of tax compliance trying to comply but having difficulty understanding tax. This significant change occurs because the Zakat scheme as a deduction of taxable income is able to eliminate the characteristic of “tax is conflicting with zakat” in the level of tax compliance resistance because the system is considered oppressive. Paper Type: Research Article.

Statistics and gap distributions in random Kakutani partitions and multiscale substitution tilings

We study statistics of tiles in random incommensurable Kakutani sequences of partitions in Rd. We provide explicit formulas that illustrate the dependence on the combinatorial structure, the volumes of the participating tiles and the entropy of the partitions in the underlying random substitution system. These improve previous results for non-random Kakutani partitions and multiscale substitution tilings, and imply a gap distribution formula for Delone sets associated with multiscale substitution tilings of the real line.

The density and minimal gap of visible points in some planar quasicrystals

It has previously been observed that the limiting gap distribution of the directions to visible points of planar quasicrystals may vanish near zero, that is, there exist planar quasicrystals with a positive limiting minimal normalised gap between the angles of visible points. The exact values of these limiting minimal normalised gaps have not been determined. In this paper we give explicit formulas for the densities of visible points for planar quasicrystals from several families, which include the Ammann–Beenker point set and the vertex sets of some rhombic Penrose tilings. Combining these results with a known characterisation of the limiting minimal gap in terms of a probability measure on an associated homogeneous space of quasicrystals, we give explicit values of the limiting minimal normalised gap between the angles of visible points for several families of planar quasicrystals, in particular, for the Ammann–Beenker point set and for the vertex sets of some rhombic Penrose tilings. We also compare our results with numerical observations.

Improving profile accuracy and surface quality of blisk by electrochemical machining with a micro inter-electrode gap

Electrochemical machining (ECM) has emerged as an important option for manufacturing the blisk. The inter-electrode gap (IEG) distribution is an essential parameter for the blisk precise shaping process in ECM, as it affects the process stability, profile accuracy and surface quality. Larger IEG leads to a poor localization effect and has an adverse influence on the machining accuracy and surface quality of blisk. To achieve micro-IEG (<50 μm) blisk finishing machining, this work puts forward a novel variable-parameters blisk ECM strategy based on the synchronous coupling mode of micro-vibration amplitude and small pulse duration. The modelling and simulation of the blisk micro-IEG machining have been carried out. Exploratory experiments of variable-parameters blisk ECM were carried out. The results illustrated that the IEG width reduced with the progress of variable parameter process. The IEG width of the blade’s concave part and convex part could be successfully controlled to within 30 μm and 21 μm, respectively. The profile deviation for the blade’s concave surface and convex surface are 49 μm and 35 μm, while the surface roughness reaches Ra = 0.149 μm and Ra = 0.196 μm, respectively. The profile accuracy of the blisk leading/trailing edges was limited to within 91 μm. Compared with the currently-established process, the profile accuracy of the blade’s concave and convex profiles was improved by 50.5 % and 53.3 %, respectively. The surface quality was improved by 53.2 % and 50.9 %, respectively. Additionally, the machined surface was covered with small corrosion pits and weak attacks of the grain boundary due to selective dissolution. Some electrolytic products were dispersed on the machined surface, and their components were mainly composed of the carbide and oxide products of Ti and Nb elements. The results indicate that the variable-parameters strategy is effective for achieving a tiny IEG in blisk ECM, which can be used in engineering practice.

Diffractive dissociation in future electron-ion colliders

We study diffractive scattering cross sections, focusing on the rapidity gap distribution in realistic kinematics at future electron-ion colliders. Our study consists in numerical solutions of the QCD evolution equations in both fixed and running coupling frameworks. The fixed and the running coupling equations are shown to lead to different shapes for the rapidity gap distribution. The obtained distribution when the coupling is fixed exhibits a shape characteristic of a recently developed model for diffractive dissociation, which indicates the relevance of the study of that diffractive observable for the partonic-level understanding of diffraction.

First measurement of the forward rapidity gap distribution in pPb collisions at 8 TeV

We present the forward rapidity gap spectra from proton-lead collisions for both \mathrm{I\!P}IP-Pb and \mathrm{I\!P}IP-p topologies measured at the CMS at a center-of-mass energy of 8.16 TeV. For the \mathrm{I\!P}IP-Pb topology, the cross-section predicted by EPOS-LHC is a factor of two lower than the data while has reasonable description of the spectrum shape. For the \mathrm{I\!P}IP-p topology, the EPOS-LHC, QGSJET~II and HIJING predictions are significantly lower than the data, what can be explained by a contribution of ultra-peripheral photoproduction events. The obtained data may be of significant input for understanding the high energy limit of QCD and modeling cosmic ray air showers.

Gap distribution mapping to visualize regions associated with type 1 endoleak in a fenestrated thoracic stent graft.

OBJECTIVESOur goal was to analyse the relationships between aortic surface irregularity and a type 1 endoleak (T1EL) after a thoracic endovascular repair using the Najuta fenestrated stent graft.METHODSThe patients who were treated using the Najuta stent graft for an intact aortic arch aneurysm at the Saitama Cardiovascular and Respiratory Center between June 2013 and June 2017 were analysed retrospectively. The primary end point was the occurrence of a T1EL. The gap between a virtual aorta and the patient's aortic wall at the stent graft fixation was calculated over the whole circumference at 1 mm intervals, and gap distribution mapping was performed. The rate of freedom from a T1EL was estimated using the Kaplan–Meier method and compared between the patients with or without a continuously malapposed region of >1 mm from the branches to the aneurysm.RESULTSTwenty-one patients were analysed. During the mean follow-up period of 21.7 months, 4 patients were confirmed to have T1ELs. Three of the T1Els were detected during the perioperative period and occurred through a fenestration. The remaining patient had a T1EL 2 years postoperatively. The gap distribution mapping confirmed the presence of a continuously malapposed region of >1 mm from the cervical branch to the aneurysm postoperatively in 4 patients with T1ELs. Patients who had a continuously malapposed region of >1 mm showed a statistically lower T1EL rate than those without (p < 0.001). Malapposed regions defined using the gap distribution mapping were consistent with flow channels through T1EL fenestrations detected using the perioperative computed tomography data.CONCLUSIONSThe gap distribution mapping could be useful to predict the occurrence of T1ELs in patients with the Najuta stent graft.

On the use of current and forward-looking data in monetary policy: a behavioural macroeconomic approach

Abstract We analyse the question of whether the use of forward-looking data in monetary policy is to be preferred over the use of current data. We use a behavioural macroeconomic model that generates periods of tranquillity alternating with crisis periods characterized by fat tails in the distribution of output gap. We find that in a strict inflation targeting (SIT) regime, the use of forward-looking data leads to a lower quality of monetary policymaking than in a dual mandate monetary policy regime, because the first regime creates more extreme movements in output and inflation than the second one. We also find that nowcasting tends to improve the quality of monetary policy, especially in a SIT regime. Finally, we provide a case study of monetary policies in the USA and the eurozone during 2000–20.