Hybrid Mode Research Articles

Theoretical modelling and experimental evaluation of thermal performance of a combined earth-to-air heat exchanger and return air hybrid system

To both alleviate thermal saturation in surrounding soil and avoid indoor air pollution caused by closed-loop earth-to-air heat exchanger (EAHE) systems, this study proposes a hybrid mode that combines EAHE and return air (RA), i.e., the EAHE-RA system. A theoretical model was proposed to predict the thermal performance of EAHE-RA systems considering both sensible and latent heat transfer inside the EAHE. Full-scale experiments on both open-loop EAHE system and EAHE-RA system were carried out. The results indicated that the average cooling capacity of EAHE in EAHE-RA system was decreased by 1202.8 W (43.82 %) in summer compared to open-loop EAHE system, while the average cooling capacity recovery of return air was 645.4 W. In winter, the average heating capacity of the EAHE of EAHE-RA system was decreased by 394.1 W (48.91 %), while the average heating capacity recovery of the return air was 1021.7 W. Theoretical predictions of EAHE outlet and indoor air temperature agree well with the measured ones in both summer and winter. Theoretical results indicated that the EAHE-RA system has lower/higher pipe wall temperatures in summer/winter than the open-loop EAHE does, indicating a lower thermal interference on surrounding soils and thus better durability.

Simulation of mode transitions in capacitively coupled Ar/O2 plasmas

In this work, the effects of the frequency, pressure, gas composition, and secondary-electron emission coefficient on the discharge mode in capacitively coupled Ar/O2 plasmas were carefully studied through simulations. Three discharge modes, i.e., α, γ, and drift-ambipolar (DA), were considered in this study. The results show that a mode transition from the γ-DA hybrid mode dominated by the γ mode to the DA-α hybrid mode dominated by the DA mode is induced by increasing the frequency from 100 kHz to 40 MHz. Furthermore, the electron temperature decreases with increasing frequency, while the plasma density first decreases and then increases. It was found that the electronegativity increases slightly with increasing pressure in the low-frequency region, and it increases notably with increasing pressure in the high-frequency region. It was also observed that the frequency corresponding to the mode transition from γ to DA decreased when the secondary-electron emission coefficient was decreased. Finally, it was found that increasing the oxygen content weakens the γ mode and enhances the DA mode. More importantly, the density of oxygen atoms and ozone will increase greatly with increasing oxygen content, which is of great significance for industrial applications.

Multidimensional dynamic control of optical skyrmions in graphene–chiral–graphene multilayers

Abstract Optical skyrmions are topological quasiparticles with a complex vectorial field structure. Their associated characteristics of ultra-small, ultra-fast and topological protection have great application prospects in high density data storage, light matter interaction and optical communication. At present, the research of optical skyrmions is still in its infancy, where the construction and flexible regulation of different topological textures are current research hotspot. Here, we combine the twist degree of freedom of materials and optical skyrmions. Based on graphene–chiral–graphene multilayers structure, we demonstrate the field mode symmetry and hybridization to form Bloch-type graphene plasmons skyrmion lattice. At the same time, by changing chirality parameter, the Fermi energy of graphene and the phase of incident light, multidimensional control of Bloch-type optical skyrmions can be realized. Our work demonstrated that the properties of materials provide the additional dimensions to regulate the topological states, and the combination of different materials structures provides the possibility for dynamic construction and manipulation of multiple topological states, which is expected to find applications in integrated nanophotonics devices.

Fiber Bragg grating sensing multiplexing method using photonic lantern spatial mode diversity

This paper introduces a method for fiber Bragg grating (FBG) multiplexing based on spatial mode diversity. By introducing the dimension of spatial modes in few-mode fibers (FMF), the FBGs are allocated into multiple optical paths carried by different spatial modes. The method involves multiplexing and detecting the reflected spectra of FBGs in various spatial modes, effectively enhancing the system's sensing capacity. The paper establishes a mode-diversity multiplexing sensing system using mode-selective photonic lanterns and FMF circulator. As a proof of concept, the system is experimentally validated for multipoint temperature sensing using four spatial modes LP01, LP11, LP21 and LP02, and its performance is compared with that of traditional multiplexing methods. The experimental results indicate that the proposed mode division multiplexing (MDM) and hybrid MDM/wavelength division multiplexing (WDM) schemes effectively enhance the sensing capacity. Furthermore, the sensitivity to temperature response for the LP01, LP11, LP21 and LP02 modes in the spatial mode diversity multiplexed sensing surpasses 0.0096 nm/°C, maintaining linearity above 97%, and the maximum error contained within 5%. The proposed method offers a novel approach to expand the capacity of sensor networks.

Tailoring thermal transport and confinement effect of GaN/Si3N4 nanowires utilizing core–shell architecture

The thermal transport properties of nanowires (NWs) can be significantly influenced by the implementation of a core-shell structure, which introduces interface scattering and phonon localization effects, opening avenues for novel applications. In this paper, we use the method of non-equilibrium molecular dynamics to simulate the effects of system temperature, cross-sectional width, and nanopillar interface on the thermal transport of GaN/Si3N4core-shell NWs. The thermal transport process of phonons in core-shell NWs is studied by calculating the vibrational density of states, phonon participation rate, and dispersion curve. The results show that the core-shell NWs characterized by smooth interfaces exhibit a 17.4% decrease in thermal conductivity (TC) at room temperature when contrasted with pristine GaN NWs. Furthermore, the TC of GaN/Si3N4core-shell NWs can be further reduced by adding nanopillars at the interface. Due to resonance effect, thus effectively regulating the thermal transport. The presence of nanopillars increases phonon-surface scattering intensity at low-frequency and modifies phonon dispersion to decrease the group velocity. In addition, the hybridization of phonon modes between those of the nanopillars and the Si3N4shell gives rise to numerous dispersionless resonance phonon modes that span the entire phonon spectrum. This research delves into the effects of nanopillars and interfaces on thermal transport, providing important guidance for understanding confinement effects and establishing a robust theoretical basis for the regulation of thermal transport.

Storing light near an exceptional point

Photons with zero rest mass are impossible to be stopped. However, a pulse of light can be slowed down and even halted through strong light-matter interaction in a dispersive medium in atomic systems. Exceptional point (EP), a non-Hermitian singularity point, can introduce an abrupt transition in dispersion. Here we experimentally observe room-temperature storing light near an exceptional point induced by nonlinear Brillouin scattering in a chip-scale 90-μm-radius optical microcavity, the smallest platform up to date to store light. Through nonlinear coupling, a Parity-Time (PT) symmetry can be constructed in optical-acoustical hybrid modes, where Brillouin scattering-induced absorption (BSIA) can lead to both slow light and fast light of incoming pulses. A subtle transition of slow-to-fast light reveals a critical point for storing a light pulse up to half a millisecond. This compact and room-temperature scheme of storing light paves the way for practical applications in all-optical communications and quantum information processing.

Adhesive and cohesive fracture of blood clots: Experiments and modeling

Blood clots represent living materials composed of a polymer network and an abundance of cells. They might fracture within the bulk material of the clot (cohesive fracture), at the interface between the clot and the surrounding tissue (adhesive fracture), or through a combination of both modes (hybrid fracture). The clot fracture within vascular systems and injury sites could lead to life-threatening conditions. Despite the significance, understanding and modeling the fracture behaviors of blood clots, including their dependence on mechanical loading and cellular components, remain in a nascent stage. In this study, we employ an integrated experimental-computational approach to comprehensively investigate the fracture behaviors of bovine blood clots. We explore various mechanical factors, substrates, and cellular components such as red blood cells (RBCs) and platelets. Our findings reveal that among various tissue substrates, blood clots exhibit the highest interfacial adhesion energy with muscle, and the lowest to the inner arterial lining, consistent with their biological function. Both interfacial adhesion energy and bulk fracture energy are rate-dependent, although they exhibit different dependencies. Also, RBCs and platelets have different effects on clot fracture. An increase in RBC content tends to toughen both adhesion and fracture of blood clots. However, an increase in platelet content enhances interfacial adhesion energy but lowers the bulk fracture energy. The platelet content also governs the shift from adhesive fracture to hybrid fracture. To model clot fracture, we developed two finite element models incorporating a coupled cohesive-zone and Mullins-effect approach to simulate pure shear fracture and peeling of blood clots. These models, validated through experimental data, elucidate the interplay between intrinsic fracture toughness, interfacial strength, and bulk energy dissipation during clot fracture. This study significantly advances our understanding of clot mechanics, providing valuable insights into the mechanics of similar living materials and the management of clot-related disorders such as hemorrhage and thrombosis.

On chip control and detection of complex SPP and waveguide modes based on plasmonic interconnect circuits

Abstract Optical interconnects, leveraging surface plasmon modes, are revolutionizing high-performance computing and AI, overcoming the limitations of electrical interconnects in speed, energy efficiency, and miniaturization. These nanoscale photonic circuits integrate on-chip light manipulation and signal conversion, marking significant advancements in optoelectronics and data processing efficiency. Here, we present a novel plasmonic interconnect circuit, by introducing refractive index matching layer, the device supports both pure SPP and different hybrid modes, allowing selective excitation and transmission based on light wavelength and polarization, followed by photocurrent conversion. We optimized the coupling gratings to fine-tune transmission modes around specific near-infrared wavelengths for effective electrical detection. Simulation results align with experimental data, confirming the device’s ability to detect complex optical modes. This advancement broadens the applications of plasmonic interconnects in high-speed, compact optoelectronic and sensor technologies, enabling more versatile nanoscale optical signal processing and transmission.

The study of propagation characteristics of the millimeter-wave vortex in magnetized plasma by using the FDTD method

It is pointed out that the millimeter-wave vortex may contribute to an efficient method of plasma heating since it was found that the millimeter-wave vortex can propagate in magnetized plasma even in which the normal plane wave is in cut-off condition. Then, it was assumed that the vortex field was the Laguerre–Gaussian (L–G) mode which is a free-space solution, but the generation and stable propagation of the L–G mode vortex are not easy in the millimeter frequency range. On the other hand, it is known that the millimeter-wave hybrid mode of the cylindrical corrugated waveguide also has vortex properties. In this paper, we investigate the propagation characteristics of a millimeter-wave vortex of a hybrid mode of a cylindrical corrugated waveguide in the magnetized plasma by using three-dimensional numerical simulations with the finite-difference time-domain (FDTD) method. It is found that the millimeter-wave vortex of hybrid mode also can propagate in the magnetized plasma even in a condition in which the normal plane wave is in cut-off condition, and the propagation power in the plasma is highly dependent on the topological charge l.

Enhancing Integrated Sensing and Communication (ISAC) Performance for a Searching–Deciding Alternation Radar-Comm System with Multi-Dimension Point Cloud Data

In developing modern intelligent transportation systems, integrated sensing and communication (ISAC) technology has become an efficient and promising method for vehicle road services. To enhance traffic safety and efficiency through real-time interaction between vehicles and roads, this paper proposes a searching–deciding scheme for an alternation radar-communication (radar-comm) system. Firstly, its communication performance is derived for a given detection probability. Then, we process the echo data from real-world millimeter-wave (mmWave) radar into four-dimensional (4D) point cloud datasets and thus separate different hybrid modes of single-vehicle and vehicle fleets into three types of scenes. Based on these datasets, an efficient labeling method is proposed to assist accurate vehicle target detection. Finally, a novel vehicle detection scheme is proposed to classify various scenes and accurately detect vehicle targets based on deep learning methods. Extensive experiments on collected real-world datasets demonstrate that compared to benchmarks, the proposed scheme obtains substantial radar performance and achieves competitive communication performance.

Sociodemographic Factors Related to Perceived Physical Activity on Chilean Adults after COVID-19 Pandemic.

The current study aimed to examine the relationship between sociodemographic variables (i.e., sex, age, marital status, educational level, socioeconomic status, and working mode) and physical activity levels declared by Chilean adults. The sample comprised 483 Chilean adults, 159 men (32.9%) and 324 women (67.1%) aged from 18 to 69 years old (36.5 ± 12.0). The participants completed an ad hoc sociodemographic online survey between December 2022 and March 2023 that included questions about characteristics of participants such as sex, age, educational level, household income, marital status, and working mode. Vigorous, moderate, and walking activities were measured using the International Physical Activity Questionnaire-Short Form (IPAQ-SF), a self-administered questionnaire. Men declared significantly higher vigorous and moderated physical activity than women. People aged 18 to 25, single or unmarried, and with the lowest household income, showed significantly higher scores in vigorous physical activity than those aged 26 to 45, cohabiting with a partner or married, and middle household income, respectively. Regarding working mode, people working at their job site said walking more than people not working, working in a hybrid mode, and working online. Our findings suggest that promoting strategies that increase physical activity during the pandemic is necessary to avoid health problems.

The impact of mental health and the COVID-19 pandemic on employability and learning outcomes: evidence from Taiwanese University students

In response to the emergence of COVID-19, schools were forced to adopt online learning, which later transitioned into a hybrid mode of teaching. However, these changes in the teaching and learning mode may have an adverse effect on mental health, thereby affecting learning outcomes. Therefore, providing immediate resource support for disadvantaged groups may improve students’ learning outcomes. This study investigated the impact of mental health on employability, learning outcomes in the context of blended learning, and the support provided by school resources among college students. We then analyzed survey data from university students and examined the associations among mental health, employability, learning outcomes before and after blended learning, frequency of seeking counseling, and school resource support. The research findings indicate that as the severity of mental health worsened, participants perceived lower learning ability for their future careers. Moreover, during the pandemic, there were variations in learning outcomes for students exposed to blended learning, but it was found that female students demonstrated better learning outcomes. It was also determined that it is beneficial for disadvantaged students to promptly apply for school resource support, as such support can contribute to improved learning effectiveness. Establishing mental health prevention mechanisms and providing school and external resources in a timely manner are the best solutions for helping students learn.

Collaborative Supervision of Guidance and Counseling Services in Hybrid Mode; A Review of Theoretical Feasibility

Collaborative Supervision of Guidance and Counseling Services in Hybrid Mode; A Review of Theoretical Feasibility

Integrating Google Classroom and Project-Based Learning for Enhanced Synchronous and Asynchronous Education

Some of them are present long before but other have been influenced by the modern challenges those are present have also radically changed the world why educational is organized and delivered, as numerous institutions have been forced from in-person classroom keeper instructing to a range of online modes. A critical tool for online learning has been Google Classroom, which combines synchronous learning (real-time) and asynchronous learning (self-paced). This work explores implementation, benefits, challenges, and effectiveness of Google Classroom fused with Project-Based Learning (PBL) for enhancing learning opportunities especially in English as Second Language (ESL) education. Results suggest that the hybrid mode allows for a balance between being less strict and enabling engagement, motivation, and achievement in those learning with other hybrid modes and those strictly synchronous or asynchronous modes.

Transient analysis of a near-zero energy building with green hydrogen production integrated with energy storage systems

The current study highlights the potential of hybrid renewable energy systems in mitigating CO2 emissions for a near-zero energy building. A Python-based controller is used to manage the state of charge (SoC) of the lithium-ion battery. Two buildings are considered in the study. Once the SoC in the first building reaches 75 %, the system prevents overcharging and redirects the green electricity towards the hybrid system for hydrogen production. To compare the role of a hybrid system in which a fuel cell is used to supply the required energy for electric load and electrolyzer demand, a diesel generator is considered for the same energy demands. The hybrid system achieves a 56.14 % reduction in diesel fuel consumption, leading to an annual decrease of 33.860 tons of CO2 emissions. Economic analysis reveals that while the cost of the diesel mode is calculated to be 96 % higher than the hybrid mode, the CO2 emissions in the hybrid mode will be 56.14 % lower than the full diesel mode. Additionally, the system's total annual hydrogen production is 7582.74 kg, with a maximum production rate of 15.52 m³/hr at 1.3 bar pressure. Despite higher initial costs, hybrid systems effectively address the challenge of CO2 emissions compared to conventional systems. The results underscore the necessity of hybrid systems for achieving significant reductions in fossil fuel consumption, presenting a sustainable solution for future energy needs.

Seat to beat: Novel capacitive ECG integration for in-car cardiovascular measurement

Cardiovascular diseases (CVD) are a leading cause of global mortality, responsible for approximately one in five deaths. In response to these concerning statistics, there is a growing need for innovative solutions enabling cardiac monitoring beyond medical facilities. This paper demonstrates the fabrication and development of a novel system designed to be integrated into passenger car seats, facilitating continuous monitoring of passengers’ cardiac activity. The system comprises a capacitive electrode prototype, a custom-designed analog signal processing circuit, and a computing unit. Two ultrathin capacitive electrodes were fabricated with a diameter of 56.42 mm protected by a guard layer to reduce noise. The amplification circuitry was comprised of operational amplifiers tasked with filtering and conditioning the electrocardiogram (ECG) signal. Heart rates calculated from our measurements were comparable with clinical ECG. The experimental setup underwent testing on human subjects while they were in a state of tranquil sitting within passenger cars and also in laboratory conditions. The proposed system offers the flexibility for single and dual power supplies in full capacitive or hybrid mode. Our experimental results confirm the system’s feasibility and its capability to record high-quality signals from weak biopotentials, highlighting its potential for real-world applications.

Development of A Project Based Learning Hybrid Mode Module to Train Science Skills for Phase D Students

Development of A Project Based Learning Hybrid Mode Module to Train Science Skills for Phase D Students

Evolutionary distribution and mode transition in medium frequency from 50 kHz to 5 MHz of argon atmospheric pressure dielectric barrier discharge plasma

Dielectric barrier discharges (DBDs) provide a promising technology for generating non-equilibrium cold plasmas at atmospheric pressure. For both application-focused and fundamental research, it is important to explore the discharge mode transition and electron heating mechanism to enable effective independent tuning of key plasma parameters in a DBD system. In this work, we report numerical studies of the effects of single-frequency excitation on atmospheric argon DBDs, which are carried out in the medium driving frequency (MF) range from 50 kHz to 5 MHz by using a one-dimensional hydrodynamics coupling model. The spatio-temporal evolution of particle density associated with the discharge mode transition and electron dynamic behavior has been investigated. By tuning different components of a single frequency, we observe the electron heating behaviors of the individual modes and mode transitions from the Townsend discharge to the glow discharge in the low frequency to the Ω mode and the hybrid mode in the medium frequency to the α-mode and the γ-mode in the radio frequency. The physical analysis is understood based on these fundamental insights into the plasma physics.

Polarization Analysis of Vertically Etched Lithium Niobate-on-Insulator (LNOI) Devices

LNOI devices have emerged as prominent contributors to photonic integrated circuits (PICs), benefiting from their outstanding performance in electro-optics, acousto-optics, nonlinear optics, etc. Due to the physical properties and current etching technologies of LiNbO3, slanted sidewalls are typically formed in LNOI waveguides, causing polarization-related mode hybridization and crosstalk. Despite the low losses achieved with fabrication advancements in LNOI, such mode hybridization and crosstalk still significantly limit the device performance by introducing polarization-related losses. In this paper, we propose a vertically etched LNOI construction. By improving the geometrical symmetry in the waveguides, vertical sidewalls could adequately mitigate mode hybridization in common waveguide cross sections. Taking tapers and bends as representatives of PIC components, we then conducted theoretical modeling and simulations, which showed that vertical etching effectively exempts devices from polarization-related mode crosstalk. This not only improves the polarization purity and input mode transmittance but also enables lower polarization-related losses within more compact structures. As a demonstration of fabrication feasibility, we innovatively proposed a two-step fabrication technique, and successfully fabricated waveguides with vertical sidewalls. Such vertical etching technology facilitates the development of next-generation high-speed modulators, nonlinear optical devices, and other advanced photonic devices with lower losses and a smaller footprint, driving further innovations in both academic research and industrial applications.

What's going on with teleworking? a scoping review of its effects on well-being.

Studies of teleworking and well-being increased dramatically during the COVID-19 pandemic. This article aims to provide an overview of this emerging body of knowledge. Following the PRISMA guidelines, we performed a scoping review using Social Sciences Citation Index (Web of Science), Sociological Abstracts (PROQUEST), and SocINDEX with full text (EBSCOhost). Articles published in English up to December 2022 were included. The result was a total of 2695 potentially relevant studies. After a double-screening procedure, 132 studies were chosen for data extraction. A content analysis was carried out to provide a summary of the social mechanisms linking teleworking to indicators of well-being related to mental health and quality of life. A complex picture of variables emerges on the impact of teleworking through direct or indirect mechanisms and a number of interactions with worker's characteristics. First, the features of the environment matter, as it affects well-being, for example, depending on a better digital infrastructure, access to daylight and sufficient space. Second, it is not only a question of "where" we telework, but also "how much". The advantages of a hybrid mode seem to be emerging to avoid an excessive lack of in-person social interaction, while offering greater flexibility in organizing daily life and reducing commuting times. Third, beyond the modalities of teleworking per se, it is key to take into account how these interact with workers' personalities, their choices and preferences, which are often dictated by the stage of life they are in, e.g., parenting and career stages. In sum, the literature suggests that a straight answer on the positive or negative effects of teleworking is neither useful nor necessary. Multiple answers are possible to unveil the specific working arrangements that makes workers' lives better according to their different needs. It seems essential to continue research on teleworking away from the exceptional stressors of the COVID-19 pandemic, which have greatly skewed the evidence on the detrimental effects of teleworking. Planning more complex research designs using longitudinal data and network analyses could improve understanding of how teleworking is changing careers, lifestyles and social relationships.