Unique Behavior Research Articles

UNIQUENESS RESULTS BASED ON DELTA FRACTIONAL OPERATORS FOR CERTAIN BOUNDARY VALUE PROBLEMS

This paper primarily lies in presenting existence and uniqueness analysis of boundary fractional difference equations of a special Riemann–Liouville operators classes. To this end, we first develop Green’s function to the corresponding fractional boundary value problems and provide boundary conditions to find the constants. Then we study the existence of solutions and we examine the bounded of their solutions. Eventually, two numerical examples are given to demonstrate the efficiency and uniqueness behavior of the boundary value problem. Furthermore, such fractional problems can typically be converted to a direct fractional problem with certain boundary or initial conditions in transport in porous media.

Existence, Uniqueness and Asymptotic Behavior of Solutions for Semilinear Elliptic Equations

A class of semilinear elliptic differential equations was investigated in this study. By constructing the inverse function, using the method of upper and lower solutions and the principle of comparison, the existence of the maximum positive solution and the minimum positive solution was explored. Furthermore, the uniqueness of the positive solution and its asymptotic estimation at the origin were evaluated. The results show that the asymptotic estimation is similar to that of the corresponding boundary blowup problems. Compared with the conclusions of Wei’s work in 2017, the asymptotic behavior of the solution only depends on the asymptotic behavior of b(x) at the origin and the asymptotic behavior of g at infinity.

On a nonhomogeneous heat equation on the complex plane

In this paper, we investigate the existence, uniqueness, and asymptotic behaviors of mild solutions of parabolic evolution equations on complex plane, in which the diffusion operator has the form [Formula: see text], where [Formula: see text], the function [Formula: see text] is smooth and subharmonic on [Formula: see text], and [Formula: see text] is the formal adjoint of [Formula: see text]. Our method combines certain estimates of heat kernel associating with the homogeneous linear equation of Raich [Heat equations in [Formula: see text], J. Funct. Anal. 240(1) (2006) 1–35] and a fixed point argument.

Existence, uniqueness, and asymptotic behaviors of ground state solutions of Kirchhoff‐type equation with fourth‐order dispersion

In this paper, we focus on the following Schrödinger–Kirchhoff‐type problem with fourth‐order dispersion: where are constants and . We make use of Nehari manifold technique together with concentration‐compactness principle to prove that the above equation has at least a ground state solution for if , 6, and 7, and for if . Moreover, we also investigate the asymptotic behaviors of ground state solutions when some coefficients tend to zero. Among them, a uniqueness result about ground state solutions is obtained by implicit function theorem, and a blow‐up result is established by Pohozaev identity if dimension .

Coexistence of two species with intra- and interspecific competition in an unstirred chemostat

In this paper, we study an intra- and interspecific competition system with the different diffusion rates in an unstirred chemostat. Due to the present of the different diffusion rates, the conservation principle for a classical standard chemostat model does not hold here. Firstly, we prove the existence, the uniqueness and asymptotic behaviors of positive solution of the single population system by using the degree theory. Secondly, by the degree theory and standard bifurcation theory, the existence and global structure of the coexistence solutions are investigated. The results show that when the maximum growth rates of two microorganisms with different diffusion abilities are not small, two competing microorganisms will coexist. Finally, numerical simulations are performed to illustrate that the interspecific interference can help the weaker competitor to win in the competition.

Many-body Effects on Electronic Transport in Molecular Junctions: A Quantum Perspective.

This concept delves into quantum particle transport at the nanoscale, with a particular focus on how electrons move through molecular circuits. The thriving field of single molecular electronics benefits from the unique electrical and other properties of nanostructures. It concentrates on single molecular junctions that serve as bridges between electrodes. In this context, the electronic correlation-induced many-body effect gives rise to resonant states. These states, along with conductance, depend on electron spin. Thus, the field acts as a bridge between quantum and macroscopic worlds, unveiling unique behaviors of electrons. Additionally, external factors, such as magnetic fields and voltages, offer means to control the electron correlation in these junctions.

Parametric magnon transduction to spin qubits.

The integration of heterogeneous modular units for building large-scale quantum networks requires engineering mechanisms that allow suitable transduction of quantum information. Magnon-based transducers are especially attractive due to their wide range of interactions and rich nonlinear dynamics, but most of the work to date has focused on linear magnon transduction in the traditional system composed of yttrium iron garnet and diamond, two materials with difficult integrability into wafer-scale quantum circuits. In this work, we present a different approach by using wafer-compatible materials to engineer a hybrid transducer that exploits magnon nonlinearities in a magnetic microdisc to address quantum spin defects in silicon carbide. The resulting interaction scheme points to the unique transduction behavior that can be obtained when complementing quantum systems with nonlinear magnonics.

Singular solutions of semilinear elliptic equations with supercritical growth on Riemannian manifolds

In this paper, we shall discuss singular solutions of semilinear elliptic equations with general supercritical growth on spherically symmetric Riemannian manifolds. More precisely, we shall prove the existence, uniqueness and asymptotic behavior of the singular radial solution, and also show that regular radial solutions converges to the singular solution. In particular, we shall provide these properties on spherically symmetric Riemannian manifolds including the hyperbolic space as well as the sphere.

Family Businesses Overcoming the COVID-19 Crisis with Innovation: An Exploratory Analysis of the Jewelry Retail Sector in Spain

Innovation is a trending topic in many disciplines but has a particular focus when it is studied in family businesses (FBs) due to their unique behavior in decision-making. Moreover, there is a gap in research on how these family businesses overcome economic crises by applying innovation. The main purpose of this paper is to provide empirical insight regarding this gap in an understudied sector, such as the Jewelry retail sector. This research was conducted in five cases, taken as examples of what these companies did, in terms of innovation, to overcome the COVID-19 crisis situation. This was considered sufficient, given the homogeneous structure of the sector and the exploratory nature of the research. The results revealed that different strategies caused them to obtain different results and clearly showed that FBs that used innovation during the crisis had better financial results. This paper contributes to the understanding of how FBs overcome economic crises by applying innovation. The implications for this type of business are also included.

Engineering ferroelectric-nanonet-based heterostructures enables superior photovoltaic effect and asymmetric switchability

Layered pervoskite ferroelectrics with a coexistence of robust spontaneous polarization and large intrinsic conductivity exhibit unique photoelectric behavior, and manipulation of photovoltaic response in such ferroelectric-based heterostructure has driven significant research activity. Herein, a Bi2WO6 layered oxide with a coexistence of ferroelectricity and 2D potential well which effectively confines carrier transport was chosen and its orientated nanonet film was formed epitaxially by pulsed laser deposition technique. An excellent platform to investigate the role of the ferroelectric-semiconductor heterostructure in tuning photovoltaic characteristics was constructed by embedding a p-type nanoscale Sb2Se3 within the n-type Bi2WO6 nanonet matrix. The desired Bi2WO6/Sb2Se3 heterostructure optimized the three key steps from light to electricity, and exhibited a large and stable photovoltaic effect, achieving three/two orders of magnitude enhancement of the short-circuit photocurrent density/open-circuit voltage under laser irradiation in its vertical structure device. What is more, an electric-field-controlled switchable asymmetric photoresponse was clearly observed in Bi2WO6/Sb2Se3 device, due to interfacial Schottky barrier formation and its width and height modulation by poling-modified ferroelectric self-polarization. In contrast to classical ferroelectric photovoltaics, the photocurrent direction of the target device after reversed poling remained unchanged, implying the significant role of the polarization-dependent interfacial effect, rather than bulk photovoltaic effect.

An analytical approach to engineer multistability in the oscillatory response of a pulse-driven ReRAM

A nonlinear system, exhibiting a unique asymptotic behaviour, while being continuously subject to a stimulus from a certain class, is said to suffer from fading memory. This interesting phenomenon was first uncovered in a non-volatile tantalum oxide-based memristor from Hewlett Packard Labs back in 2016 out of a deep numerical investigation of a predictive mathematical description, known as the Strachan model, later corroborated by experimental validation. It was then found out that fading memory is ubiquitous in non-volatile resistance switching memories. A nonlinear system may however also exhibit a local form of fading memory, in case, under an excitation from a given family, it may approach one of a number of distinct attractors, depending upon the initial condition. A recent bifurcation study of the Strachan model revealed how, under specific train stimuli, composed of two square pulses of opposite polarity per cycle, the simplest form of local fading memory affects the transient dynamics of the aforementioned Resistive Random Access Memory cell, which, would asymptotically act as a bistable oscillator. In this manuscript we propose an analytical methodology, based on the application of analysis tools from Nonlinear System Theory to the Strachan model, to craft the properties of a generalised pulse train stimulus in such a way to induce the emergence of complex local fading memory effects in the nano-device, which would consequently display an interesting tuneable multistable oscillatory response, around desired resistance states. The last part of the manuscript discusses a case study, shedding light on a potential application of the local history erase effects, induced in the device via pulse train stimulation, for compensating the unwanted yet unavoidable drifts in its resistance state under power off conditions.

Trustworthy interaction model: continuous authentication using time–frequency joint analysis of mouse biometrics

ABSTRACT The rapid development of information technology attracts more attention to information security. Static authentication (SA) technology is widely used in account protection. However, once this shield is broken, it will lead to a serious information security crisis. Therefore, we propose a trustworthy interaction model that continuously authenticates users’ human–computer interaction behaviour, which is a supplement to SA. Specifically, the Hilbert–Huang transform is used to extract time-frequency domain features of user mouse behaviour. Then, the users’ unique mouse behaviour patterns are modelled by LSBT to quantify the deviation between current mouse behaviour and true patterns. Finally, the dynamic trust model is deployed to continuously monitor the current user’s identity credibility score in human-computer interaction. Notably, a 30+ month dataset of the mouse behaviours of 32 participants is collected from a real website to prove the effectiveness of TIM. Two real-world scenarios, comprising 1,344 attacks, were simulated to evaluate the trustworthy interaction model performance. All 1,344 attacks were successfully detected, with an average time of 1.63 min to lock imposters out. The TIM is easy to deploy to continuously authenticate users and can accurately and quickly detect imposters.

Rush to Charge, Dead to Drive: Application of Deadline Rush Model to Electric Vehicle User's Charging Behavior.

This work aims to estimate the portion of electric vehicle (EV) users who exhibit procrastination-like behavior, almost equivalent to an "empty" battery, before they decide to charge their vehicles. There is a human tendency to procrastinate when a deadline approaches. Human behavior in the presence of deadlines has been studied in different fields to evaluate individuals' performance or organizational efficiency and effectiveness. However, this phenomenon has not been investigated among EV users. This study explores users' procrastination-like behavior among 69 Rhode Island public charging stations' data representing 70,611 charging events. The Deadline Rush Model is incorporated to model frequent users' charging profiles. To conduct a robust estimation, the Bayesian Mixture Model is implemented. With the selection of an informative prior, the Bayesian Mixture Model estimated that almost one-third of frequent users procrastinate charging. The majority of procrastination-like users have small battery sizes. Although procrastination-like users need to charge when they arrive at a location, that might not necessarily be true for a plug-in hybrid; thus, systematically, they can clog the system for other users whose needs are more pressing. Understanding unique and unexplored charging behaviors among EV users is beneficial to EV infrastructure stakeholders in reducing the adoption threshold by providing a reliable and ubiquitous charging network. The findings identify a different kind of demand on the EV infrastructure than previously modeled and can directly influence future decision-making criteria in terms of planning to optimize to accommodate EV drivers with different charging behaviors.

Phase Behavior of Polydisperse Y-Shaped Polymer Brushes under Good Solvent Conditions.

Y-shaped polymer brushes represent a special class of binary mixed polymer brushes, in which a combination of different homopolymers leads to unique phase behavior. While most theoretical and simulation studies use monodisperse models, experimental systems are always polydisperse. This discrepancy hampers linking theoretical and experimental results. In this theoretical study, we employed dissipative particle dynamics to study the influence of polydispersity on the phase behavior of Y-shaped brushes grafted to flat surfaces under good solvent conditions. Polydispersity was kept within experimentally achievable values and was modeled via Schulz-Zimm distribution. In total, 10 systems were considered, thus covering the phase behavior of monodisperse, partially polydisperse and fully polydisperse systems. Using such generic representation of real polymers, we observed a rippled structure and aggregates in monodisperse systems. In addition, polydisperse brushes formed a stable perforated layer not observed previously in monodisperse studies, and influenced the stability of the remaining phases. Although the perforated layer was experimentally observed under good solvent conditions and in the melt state, further confirmation of its presence in systems under good solvent conditions required mapping real polymers onto mesoscale models that reflected, for example, different polymer rigidity, and excluded volume effects or direct influence of the surface, just to mention a few parameters. Finally, in this work, we show that mesoscale modeling successfully describes polydisperse models, which opens the way for rapid exploring of complex systems such as polydisperse Y-shaped brushes in selective or bad solvents or under non-equilibrium conditions.

The Impact of School Leaders on Teachers’ Engagement in School Improvement Through an Intergenerational Diversity Lens

The aim of the research study is to analyse how the leadership of school leaders could encourage teachers to participate more effectively in school improvement, taking into account the different generations of teachers and the specificities of those generations. The scientific literature suggests that a specific focus on intergenerational diversity is necessary to better understand differences in teacher engagement in school improvement. A qualitative methodology was chosen to provide a comprehensive and in-depth understanding of the participants’ real-world experiences and their subjective interpretations of those experiences. Fifteen school leaders from general education schools in Lithuania participated in the focus group discussion, and provided insights on how school leaders’ leadership may impact teachers’ engagement in school improvement initiatives, with the focus on addressing generational diversity. The proposed study does not aim to promote intergenerational stereotypes, but rather to focus on unique intergenerational values, behaviours and skills. The findings would be useful in developing research-based recommendations for school leaders’ practices (e.g. recruitment and retention, job satisfaction, career development, motivation and empowerment, teacher role and performance, leadership, etc) for encouraging groups of teachers of different generations to become more engaged in school improvement.

Mechanical‐wear behavior and microstructure analysis of Al2214 alloy with B4C and graphite particles hybrid composites

AbstractIn the present work, hybrid composites made of Al2214 alloy with B4C and graphite were produced by using a liquid metallurgical process. Al2214 alloy was utilized to create hybrid composites that had 1.5–6 wt% of B4C particles and a constant 3 wt% of graphite particles. Microstructural analysis using scanning electron microscope (SEM), energy dispersion spectroscopy (EDS), and X‐ray diffraction (XRD) was done on the produced composites. The density, hardness, ultimate, yield strength, and elongation as a percentage were carried out using ASTM E8 for tensile and E10 standard for hardness test. The wear behavior of Al2214‐B4C and graphite composites was examined as per ASTM G99 standard using a wear testing device under a variety of loads and rotation speeds. Graphite and boron carbide particles were equally dispersed throughout the Al2214 alloy, according to SEM photographs. Graphite and B4C particles were detected in the Al2214 alloy by EDS and XRD analyses. The density of Al alloy composites was decreased by adding dual particles to the matrix. The Al2214 alloy's hardness, ultimate strength, yield strength, and wear resistance were all enhanced by the inclusion of dual particles, which increased these properties by 15.4%, 40.4%, and 46.7%, respectively. The presence of hybrid particles in the Al2214 alloy was revealed by EDS and XRD patterns. The density of Al alloy composites was decreased by adding dual particles to the matrix. Tensile force micrographs provided further evidence of the unique fracture behaviors shown by the Al2214 alloy and its composites. In order to examine the wear mechanisms and different morphologies of worn surfaces, scanning electron micrographs were taken.

Unique gap-related SERS behaviors of p-aminothiophenol molecules absorbed on TiO2 surface in periodic TiO2/Ni nanopillar arrays

We observed a unique interpillar gap-related surface-enhanced Raman scattering (SERS) behavior of p-aminothiophenol (PATP) molecules from periodic TiO2 nanopillar arrays with three gap sizes of 191, 297 and 401 nm, which is completely different from that on Ag and Ni nanopillar arrays. Especially, the gap-size-dependent charge-transfer (CT) resonance enhancement from TiO2/Ni has been indicated through comparisons of variation trend of SERS intensities with inter-pillar gap size between TiO2/Ni and Ag/TiO2/Ni as well as Ni nanoarrays, and been confirmed by spectra of ultraviolet–visible absorption and photoluminescence. Results demonstrate that the CT resonance enhancement is more susceptible to the change of the gap size compared with the surface plasmon resonance (SPR) enhancement in TiO2/Ni nanoarrays. Hence, SPR and CT enhancement showing different variation trend and rate with the gap size that leads to a different relative contribution of CT resonance to the overall SERS enhancement as gap size changes, and consequently results in a unique gap-related SERS behavior for TiO2/Ni nanoarrays. The present study is not only helpful for investigating SERS mechanism for semiconductors but also providing a method to design and optimize periodic metal/semiconductor SERS substrates in a controllable way.

Reliability of Copper Sintered Interconnects under Extreme Thermal Shock Conditions

Copper flakes-based sinter paste showed high reliability under thermal shock conditions. A dense and homogeneous interconnect was realized while sintering for 5 min at 275°C under 15 MPa bonding pressure, with the flakes showing the unique behavior of stacking over each other to realize a dense and homogeneous interconnect. Porosity under 10% could be achieved. The paste could be sintered under a constant nitrogen flow and did not need a fully inert atmosphere during sintering. Under high stress thermal shock cycling of +175/-65°C, the sintered interconnects showed a drop of 25% in the shear strength values after 1000 TST, consistent with observations made with Ag sintering. Thermal conductivity more than 200 W/mK and electrical conductivity of 20 Ms/m is achieved using the Cu sinter paste.

Dynamic responses of steady-state transition structures under impact loading

Advancements in materials science and mechanical system have spurred widespread investigation into non-traditional structures. In particular, engineers have shown interest in steady-state transition structures with phase transition properties. In this paper, a three-dimensional steady-state transition structure was established using the genetic algorithm and three-dimensional expansion, on which the low-velocity impact tests were carried out. Force response and energy absorption of the steady-state transition structures under impact were studied. From the force response and energy absorption curves, it can be seen that the steady-state transition structures absorb and store portion of impact energy temporarily, gradually releasing it after impact peak. This unique energy behavior results in a steady state transition structure with a long impact response time and a low peak impact force under impact. In addition, investigation into energy transfer within these structures reveals that energy oscillations occur among multilayered bistable surfaces during steady-state transitions, further improving the energy dissipation. Further, the dynamic response and damage modes of the honeycomb structure and the steady state transition structure were compared, showing that the damage mode of the steady state transition structure under the impact is an overall damage, in contrast to the penetration damage of the honeycomb structure. Notably, the steady-state transition structures showcase a higher proportion of elastic strain energy during impacts, effectively delaying structural damage onset, and dispersing impact energy, thus enhancing impact resistance. In light of these findings, the demonstrated behavior of steady-state transition structures in absorbing and dissipating impact energy showcases their potential as promising avenues for the development of more effective impact protection strategies.

An acetate electrolyte for enhanced pseudocapacitve capacity in aqueous ammonium ion batteries

Ammonium ion batteries are promising for energy storage with the merits of low cost, inherent security, environmental friendliness, and excellent electrochemical properties. Unfortunately, the lack of anode materials restricts their development. Herein, we utilized density functional theory calculations to explore the V2CTx MXene as a promising anode with a low working potential. V2CTx MXene demonstrates pseudocapacitive behavior for ammonium ion storage, delivering a high specific capacity of 115.9 mAh g−1 at 1 A g−1 and excellent capacity retention of 100% after 5000 cycles at 5 A g−1. In-situ electrochemical quartz crystal microbalance measurement verifies a two-step electrochemical process of this unique pseudocapacitive storage behavior in the ammonium acetate electrolyte. Theoretical simulation reveals reversible electron transfer reactions with [NH4+(HAc)3]···O coordination bonds, resulting in a superior ammonium ion storage capacity. The generality of this acetate ion enhancement effect is also confirmed in the MoS2-based ammonium-ion battery system. These findings open a new door to realizing high capacity on ammonium ion storage through acetate ion enhancement, breaking the capacity limitations of both Faradaic and non-Faradaic energy storage.