Gap Size Research Articles

HAVEN: Haptic And Visual Environment Navigation by a Shape-Changing Mobile Robot with Multimodal Perception.

Many animals exhibit agile mobility in obstructed environments due to their ability to tune their bodies to negotiate and manipulate obstacles and apertures. Most mobile robots are rigid structures and avoid obstacles where possible. In this work, we introduce a new framework named Haptic And Visual Environment Navigation (HAVEN) Architecture to combine vision and proprioception for a deformable mobile robot to be more agile in obstructed environments. The algorithms enable the robot to be autonomously (a)predictive by analysing visual feedback from the environment and preparing its body accordingly, (b)reactive by responding to proprioceptive feedback, and (c)active by manipulating obstacles and gap sizes using its deformable body. The robot was tested approaching differently sized apertures in obstructed environments ranging from greater than its shape to smaller than its narrowest possible size. The experiments involved multiple obstacles with different physical properties. The results show higher navigation success rates and an average 32% navigation time reduction when the robot actively manipulates obstacles using its shape-changing body.

Synthesis and characterization of Nd‐TiO2 and Nd‐ZnO nanostructures for photocatalytic degradation of textile wastewater

AbstractThis study was executed on textile wastewater degradation using laboratory‐prepared Nd‐TiO2 and Nd‐ZnO nanostructures by sol–gel and hydrothermal ultrasonication methods, respectively. The synthesized nano‐photocatalysts were fully characterized using XRD, FE‐SEM/EDX, FT‐IR, and UV‐DRS. The XRD analysis shows that TiO2 crystalline size with Nd doping is 6.14 nm with only the anatase phase, whereas ZnO is 29.59 nm. DRS spectra show that the energy band gap of the doped TiO2 nanostructure was 3.16 eV, whereas, in the case of the Nd‐ZnO nanostructure, it was 3.19 eV, which further indicates more photocatalytic activity. Photocatalytic application for textile wastewater degradation was tested regarding biological oxygen demand and chemical oxygen demand. The maximum degradation of textile wastewater at dilution 1:9 was observed to be 96% and 91% for Nd‐TiO2 and 89% and 87% for Nd‐ZnO under UV and solar irradiations, respectively, with the optimized catalyst dose of 0.2 g/L (Nd‐TiO2) and 0.3 g/L (Nd‐ZnO) at a pH of 7.52. The recyclability shows a slight decrease in efficiency throughout five cycles. The photocatalytic activity of Nd‐TiO2 was higher due to the favorable band gap and smaller crystallite size. The findings indicate that solar light may be a long‐term, cost‐effective renewable source for large‐scale wastewater treatment.

Mitigating interface damping of metal adhesion layers of nanostructures through bright-dark plasmonic mode coupling

Metal (such as Cr, Ti, etc.) adhesion layers, which are generally used to prevent nanostructures from falling off during electron beam lithography processes, will introduce interface damping, decrease the near-field enhancement, and shorten the dephasing time of localized surface plasmons (LSP). Maintaining metal adhesion layers while alleviating the induced interface damping in nanostructures is crucial for high-performance sensing, surface-enhanced Raman scattering elements, plasmon-based photocathodes, and plasmon-mediated catalysis. Here, we experimentally demonstrated that the mitigation of interface damping of metal adhesion layers can be achieved through the coupling between the bright and dark plasmonic modes of gold nanorods. We attribute the mitigation to stronger confinement across the plasmon energy, which effectively reduces the proportion of plasmon energy injected into the Cr adhesive layers. Compared to weak coupling, the non-radiative damping of plasmonic modes 1 and 2 is reduced by approximately 74% and 85%, respectively, under strong coupling conditions. The experimental results are supported by finite-difference time-domain simulations and are well explained by the calculated interaction potential for different gap sizes. This research will further benefit applications where low interface damping is required, such as the construction of low-threshold nanolasers and ultrasensitive sensing systems.

Electrode materials optimize operating voltage and switching speed in micro/nano plasma ultrafast devices

Abstract The trade-off between ultrahigh speed and low operating voltage is a major challenge in the continuous improvement of modern electronics. Although micro/nano plasma devices have demonstrated the potential of picosecond switching speed and high output power, surpassing traditional electronic devices, versatile methods for optimizing the operating voltage and switching speed are highly desired. Here, an optimization scheme based on the work function of the electrode materials is reported, which reduces the operating voltage and improves the switching speed. Compared with traditional methods, such as narrowing gaps or distorting electric fields, this approach offers advantages such as reducing production costs, enhancing consistency, and improving tunability. The experimental results show that using silver as a low-work-function electrode material can reduce the operating voltage by 55% to 180 V and increase the switching speed by 58% to 7.1 V/ps compared to platinum, which is equivalent to a 71% reduction in gap size. In addition, the underlying working mechanisms and inherent advantages of the approach are demonstrated, providing new insights for the ultrahigh switching speed and low-power application of micro/nano plasma devices, such as high-speed communication and ultrafast electronics.

К РАСЧЕТУ ЖИДКОСТНЫХ ТАРЕЛЬЧАТЫХ СЕПАРАТОРОВ С ПАРАБОЛИЧЕСКИМИ ВСТАВКАМИ

The object of the study is liquid disk separators with curvilinear inserts, which are described by equations of the type . The study was conducted to study the effect of the insert shape on the intensity of the centrifugal force on the liquid flow, as well as on the length of the sedimentation path (or float) of dispersed medium particles. The efficiency of clarification of dispersed media is predetermined by two design characteristics of the device - the length of the particle sedimentation path and the direction of the centrifugal force relative to the walls of the curved channel. For parabolic inserts, the distance between them and the angle of inclination of the walls are variable quantities. To calculate these quantities, nonlinear equations are constructed and an algorithm for numerical calculations is proposed. The calculation results are presented as graphical dependencies of the above parameters along the channel length. The calculations were performed for paraboloids of revolution with degrees m=2, 3 and 4 at coefficient a=2, 3 and 4. As the coefficient a increases, the distance between the inserts decreases. The influence of the exponent m on the gap between the paraboloids of revolution is more complex. The gap size along the channel length decreased from 3 cm to several millimeters. The angle of inclination of the walls relative to the rotation axis decreased in the range from 70 to 10 degrees. As the parameters a and m increase, this angle decreases, therefore, the component of the centrifugal force directed perpendicular to the channel wall increases. The equations of motion of the liquid system were solved by the method of equal flow surfaces, according to which the flow is represented as several layers with their own velocities. At the inlet section, the velocity diagram develops from a flat profile to a parabolic form. As a result of the action of the centrifugal force, an asymmetry of the velocity profile is observed. The obtained results can be used to justify the geometric characteristics of a plate separator with parabolic inserts and to coordinate them with the flow regime parameters.

A novel approach to detailed modeling and simulation of water-gap membrane distillation: Establishing a numerical baseline model

In water-gap membrane distillation (WGMD), natural convection within the water gap significantly impacts performance and thermal efficiency. Previous studies have used empirical or modified empirical correlation models to predict the Nusselt number within the water gap, investigating how natural convection affects WGMD performance and thermal efficiency. However, these models are specific to certain operating conditions, limiting their application in developing a comprehensive numerical model for the WGMD process. To address this limitation, we developed a numerical model by integrating a two-dimensional natural convection model within the water gap. Experimental investigations were conducted across a wide range of feed temperatures and water gap sizes to assess the influence of key operating parameters on performance. To validate the effectiveness of the proposed numerical model, the experimental results were compared with those from the proposed model and with results from numerical models used in previous studies. The proposed numerical model demonstrated a maximum deviation of 8.5% from the measured data, whereas the numerical models used in previous studies exhibited deviations of 22.9%. In addition, the flow characteristics within the water gap were analyzed through isotherms and streamlines, and the improved thermal efficiency of WGMD compared to direct contact membrane distillation (DCMD) was explored.

Seismic Responses and Overturning Resistance Capacity of Base-Isolated Structures Under the Influence of Pounding Interactions with Adjacent Structures

Seismic accelerations and interlayer displacements can be reduced by Laminated Rubber Bearings (LRBs) efficiently. Isolators would amplify the displacement of the superstructure by extending the natural period, thereby reducing acceleration and seismic damage. However, as a result, the risk of pounding with adjacent structures would be raised. This study investigated the seismic responses and overturning resistance capacity of base-isolated structures subjected to pounding against an adjacent structure. Parameter studies were conducted to evaluate the effects of gap size, pounding stiffness, and horizontal stiffness of the isolation layer. Results show that poundings are characterized by intense, short forces causing acceleration spikes, amplifying the overturning coefficient and risk. The overturning risk initially decreases then increases with gap size under pulse-like earthquakes, while wider gaps mitigate effects during non-pulse events. Increased pounding stiffness intensifies poundings, heightening vulnerability. The structure’s overturning resistance initially improves with increased horizontal stiffness of the isolation layer but declines excessively with further stiffness increase.

Enhanced Broadband Tri-Stable Energy Harvesting System by Adapting Potential Energy – Experimental Study

Abstract This paper presents the process optimization of some key parameters, such as the size of the air gap and distance between fixed neodymium magnets to enhance the vibration-based energy harvesting effect in the tri-stable energy harvesting systems and the improved tri-stable energy harvesting system being the proposed solution under weak excitation. In order to do it, firstly the distributed parameters model of the magnetic coupling energy harvesting system, including macro fiber composites of the 8514 P2 with a homogenous material in the piezoelectric fiber layer and nonlinear magnetic force, was determined. The performed numerical analysis of the conventional and the improved tri-stable energy harvesting system indicated that introducing an additional magnet to the tri-stable system leads to the shallowing of the depth of a potential well by decreasing the air gap between magnets and consequently generating higher power output and improving the effectiveness of the proposed improved tri-stable energy harvesting system. Experiments carried out on the laboratory stand allowed us to verify the numerical results as well as determine the optimal parameters of the magnetic coupling system. Due to it, the effectiveness of the proposed system versus the conventional tri-stable energy harvesting system is most enhanced.

The impact of leak gap size and position on surgical mask performance of source control: A numerical study

Surgical masks are widely used for infectious source control by preventing infected individuals from transmitting pathogens. However, poor fit can create gaps between the mask and face, reducing their effectiveness. In this study, a numerical model was developed based on realistic surgical mask geometry with peripheral gaps of varying sizes and positions, fitted onto a breathing manikin. Exhalation leakage airflow dynamics and aerosol pathogen dispersion were investigated using a validated computational fluid dynamics (CFD) model with porous media. Results indicate that despite the presence of leaks, surgical masks are effective in controlling the spread of pathogens, with maximum airflow leakage at 9.11% and pathogen leakage at 16.83%. The average velocity of leaked airflow ranged from 0.12 m/s to 1.43 m/s, depending on the gap size and position. The position of the gap had little impact on the airflow and pathogen leakage fractions. Correlations between the average velocity of net leakage flow, leakage fractions of airflow and pathogens, and gap size were developed. Pathogens spread most widely from bottom leaks, followed by side and top leaks, with bottom leaks releasing up to 9.7 times more contaminated air than top leaks and 6.5 times more than side leaks. The findings also suggest that smaller gaps are associated with higher initial velocities of leakage, which in turn lead to wider dispersion of pathogens.

Population ageing and health financing: A method for forecasting two sides of the same coin

Abstract There is a perception that population ageing will have deleterious effects on future health financing sustainability. Given the positive association between health care utilization and increasing calendar age, many analysts assume population ageing will result in considerable growth in health spending. Since this expenditure tends to be sourced primarily from public funds, there is great policy interest to quantify how population ageing is likely to affect health expenditure trends. We propose a new method-the Population Ageing financial Sustainability gap for Health systems (or alternatively, the PASH)-to explore how changes in the population age mix will affect health expenditures and revenues. Using a set of six countries in Europe and the Western Pacific representing a diverse range of health financing systems (Australia, Bulgaria, Japan, Slovenia, United Kingdom, Vietnam), we forecast the size of the ageing-attributable gap between health revenues and expenditures from 2020 to 2100 under current health financing arrangements. The largest gap by 2100 is expected to be in Vietnam, where the gap between revenues and expenditure is expected to increase by around $170 per person in 2018 PPPs or 2.3% of GDP; 87.1% of this increase is due to expected growth in expenditures. In Slovenia, where the gap is forecast in line with the forecast for Japan (the oldest country in the world), nearly half of the gap (44.2%) is due to reductions in revenue generation. All countries face some health financing gap due to ageing under current financing arrangements. The PASH analysis highlights the wide range of policy options available to manage health financing as the population ages, such as changing sources for health revenues and reducing expenditure by promoting healthy ageing.

Risk-taking Factors in a Dynamic Approach

The most common definition of risk is quantified by the probability of an adverse event occurring and the value of the adverse consequence. Theoretically, the decision to take a risk can also be based essentially on these two pieces of information. In addition, according to traditional risk-taking models, the perception of risk, the psychological characteristics of the decision-makers and their relevant experience are also important. In the case of mathematical-statistical-psychological models, little emphasis is placed on the fact that risk is in fact the inability to completely control the activity in question. The causes of this incompleteness are based on the shortcomings in the relevant capabilities of the economic agent. Economic agents have different capabilities, so they rarely face the same risks, even for almost identical activities. Just as the requirements and circumstances of the activity are constantly changing, so are the capabilities of the economic agent. Consequently, the size of the capability gap of an economic agent is also constantly changing. This should be taken into account in risk-taking decisions and their revision. The paper attempts to model this dynamic risk-taking mechanism and to show how different risk-taking strategies may be pursued by economic agents in certain baseline situations.

Optimum joint gap size in bridges with Ductile Piers

Optimum joint gap size in bridges with Ductile Piers

Adjacent Buildings Subjected to Seismic Pounding: A systematic Comprehensive Review

Buildings next to one another that are too close together or have differing dynamic properties may vibrate out of phase during earthquakes. This leads to slamming of these buildings against one another. Provision to avoid this pounding effect is given in various codes. When the structures are exposed to external excitation, the dynamic properties of the nearby structures cause the structures to oscillate out of phase. Impacts will happen if the space between the structures is not large enough to support the lateral displacements brought on by this out-of-phase oscillation. The excitation characteristics, the current separation gap size, and the degree of variation between the dynamic properties of the impacting structures all influence the impact forces and impact locations along the heights of the structures. This work provides a detailed investigation of the impact of pounding in both structures that have undergone site-specific analysis and those that have not. If the interaction between the soil and structure is not taken into account during the designing process, the effects of seismic pounding are exacerbated. In addition, this paper analyses a number of research that examine the connection between soil structure and seismic pounding.

A new approach to investigate secondary hydriding phenomenon on M5Framatome clads under high–temperature LOCA conditions

The focus of this study is about a new experimental approach for a separate effects study of the secondary hydriding phenomenon under LOCA conditions. Many nuclear institutes perform semi–integrals tests to study the cladding behaviour during a LOCA transient. Those tests combined several phenomena and performing a detailed analysis of the secondary hydriding phenomenon using these tests can be challenging. A dedicated experimental protocol aiming at simulating secondary hydriding has been set up. Separate effects tests (SETs) were then carried out using this protocol to study the effects of both oxidation duration and temperature, on the hydrogen absorption during the oxidation stage of the LOCA transient on M5Framatome11M5 and M5Framatome are trademarks or registered trademarks of Framatome or its affiliates, in the USA or other countries. cladding. The effects of gap size were also investigated. Metallographic analysis has been used to characterise the M5Framatome clad metallurgical transformation after the high–temperature (HT) oxidation.

Pseudoscalar mesons from a PNJL model at zero temperature

We study pseudoscalar π\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\pi $$\\end{document}, K and η\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\eta $$\\end{document} meson properties, such as masses and couplings, in dense matter at zero temperature. We use a recently proposed phenomenological quark model, known as the PNJL0, which takes into account the confinement/deconfinement phase transition by means of the traced Polyakov loop (Φ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\varPhi $$\\end{document}) which serves as an order parameter at zero temperature. We consider two different scenarios, namely, symmetric quark matter with equal chemical potentials for all the flavors, and the beta equilibrated matter. In the latter case the hadron-quark phase transition is implemented by a two model approach. For the hadron side we use a relativistic mean-field model with density dependent couplings. We show that Φ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\varPhi $$\\end{document} induces abrupt changes in the mesons properties with gap sizes regulated by the phenomenological gluonic sector of the model.

A piezoresistive dielectric elastomer switch consisting of inkjet-printed carbon black

The piezoresistive effect is a key physical property utilized in soft and stretchable electronics, functioning as intrinsic electromechanical sensors. However, most conventional piezoresistive sensors can only passively measure and quantify external stimuli. To address these limitations, this work integrates an inkjet-printed piezoresistive pattern and a dielectric elastomer actuator (DEA) into a single monolithic dielectric elastomer film, creating a dielectric elastomer switch (DES). This DES can realize dramatic resistance changes along with DEA actuation, leveraging DEA-driven piezoresistivity for active and effective circuit control and signal processing. Theoretically, the DES operates by exhibiting resistance change through the periodic compression induced by DEA actuation. Experimentally, the piezoresistive pattern and the DEA electrodes were fabricated on an acrylic dielectric elastomer (VHB) using inkjet-printed piezoresistive carbon black (CB) and manually brushed conductive grease, respectively. The optimized DES demonstrated approximately 3.77 (±0.11) orders of magnitude in resistance change at a DEA frequency of 0.1 Hz. Compared to previously reported methods (smearing and stamping), inkjet-printed CB patterns showed significant improvements. These included negligible Joule heating impact, precise digital fabrication control, larger resistance change (up to 3.77 orders of magnitude), faster response speeds to DEA actuation (∼0.25 s for 3 orders of magnitude in resistance change), and greater durability (operating at 0.5 Hz for 112 min). Scanning electron microscopy (SEM) characterization revealed that these improvements were attributed to a more uniform distribution of conductive “CB islands” and appropriate non-conductive gap size among them. For demonstrating the applications of DES, it was employed for LED control, DEA-based soft gripper control, and as a multiplexer for signal processing.

Dynamic of mode transition in air surface micro-discharge plasma: reactive species in confined space

Abstract Flexible surface micro-discharge plasma is a non-thermal plasma technique used for treating wounds in a painless way, with significant efficacy for chronic or hard-to-heal wounds. In this study, a confined space was designed to simulate wound conditions, gelatin was used to simulate wound tissue. The distinctions between open and confined spaces were explored, and the effects of temperature, humidity, discharge power, and the gap size within the confined space on the plasma characteristics were analyzed. It was found that, temperature, humidity and discharge power are important factors that affect the concentration distribution of active components and the mode transition between ozone and nitrogen oxides. Compared to open space, the concentration of ozone in confined space was relatively lower, which facilitated the formation of nitrogen oxides. In open space, the discharge was dominated by ozone initially. As temperature, humidity and discharge power increased, nitrogen oxides in the gas-phase products were gradually detected. In confined space, nitrogen oxides can be detected at an early stage and at much higher concentrations than ozone concentration. Furthermore, as the gap of the confined space decreased, the concentration of ozone was observed to decrease while that of nitrate increased, and the rate of this concentration change was further accelerated at higher temperature and higher power. It was shown that ozone concentration decreased from 0.11 µmol to 0.03 µmol and the nitrate concentration increased from 20.5 µmol to 24.5 µmol when the spacing in the confined space was reduced from 5 mm to 1 mm, the temperature of the external discharge was controlled at 40 °C, and the discharge power was 12 W. In summary, this work reveals the formation and transformation mechanisms of active substances in air surface micro-discharge plasma within confined space, providing foundational data for its medical applications.

Why scanning tunneling spectroscopy of Sr2RuO4 sometimes doesn’t see the superconducting gap

Scanning tunneling spectroscopy (STS) and scanning tunneling microscopy (STM) are perhaps the most promising ways to detect the superconducting gap size and structure in the canonical unconventional superconductor Sr2RuO4 directly. However, in many cases, researchers have reported being unable to detect the gap at all in STM conductance measurements. Recently, an investigation of this issue on various local topographic structures on a Sr-terminated surface found that superconducting spectra appeared only in the region of small nanoscale canyons, corresponding to the removal of one RuO surface layer. Here, we analyze the electronic structure of various possible surface structures using first principles methods, and argue that bulk conditions favorable for superconductivity can be achieved when removal of the RuO layer suppresses the RuO4 octahedral rotation locally. We further propose alternative terminations to the most frequently reported Sr termination where superconductivity surfaces should be observed.

Pulse dynamic regulation of electrochemical discharge milling by utilizing the slotted tube electrode

Electrochemical discharge machining (ECDM) has a splendid application potential for machining difficult-to-cut materials. It is a challenge to limit and control the discharge energy and area of DC power supply in ECDM. Owing to the uncertainty and randomness of the position and range of the single discharge, the unpredictable discharges deteriorate the surface quality of the workpiece, alter the size of the inter-electrode gap (IEG), and influence the distribution of the multi-physical fields. Therefore, to regulate the machining state and energy, the ideology of pulse dynamic machining is introduced, and a method of pulse dynamic ECDM utilizing the slotted electrodes is proposed. With the tool electrode rotating, the tube electrode transforms the pure electrochemical machining (pure-ECM) stage and the electrochemical discharge machining (ECDM) stage periodically through the slots at the bottom of it. The machining current waveform, surface roughness and sidewall taper of machined grooves, material removal rate (MRR), and relative tool wear rate (RTWR) are investigated. Additionally, the discharge types of the ECDM are explicitly defined and statistically classified. The experimental results show that the pulse dynamic regulation of hybrid machining using the slotted electrodes is beneficial to regularize the machining current waveform and optimize the machining quality.

Effects of XX catalysts on quantum annealing spectra with perturbative crossings

In adiabatic quantum computation the required run-time to reach a given ground-state fidelity is dictated by the size of the minimum gap that appears between the ground and first-excited state in the annealing spectrum. In general the presence of avoided level crossings demands an exponential increase in the annealing time with the system size which has consequences both for the efficiency of the algorithm and the required qubit coherence times. One promising avenue being explored to produce more favorable gap scaling is the introduction of nonstoquastic XX couplings in the form of a catalyst—of particular interest are catalysts which utilize accessible information about the optimization problem in their construction. Here we show extreme sensitivity of the effect of an XX catalyst to subtle changes in the encoding of the optimization problem. In particular, we observe that a targeted catalyst containing a single coupling can significantly reduce the gap closing with system size at an avoided level crossing. For slightly different encodings of the same problems however, these same catalysts result in closing gaps in the annealing spectrum. To understand the origin of these closing gaps, we study how the evolution of the ground-state vector is altered by the presence of the catalyst and find that the negative components of the ground-state vector are key to understanding the response of the gap spectrum. We also consider how and when these closing gaps could be utilized in diabatic quantum annealing protocols—a promising alternative to adiabatic quantum annealing in which transitions to higher energy levels are exploited to reduce the run time of the algorithm. Published by the American Physical Society 2024