Energy Transport Research Articles

Frequency-Dependent Vibronic Effects in Steady State Energy Transport.

The interplay between electronic and intramolecular high-frequency vibrational degrees of freedom is ubiquitous in natural light-harvesting systems. Recent studies have indicated that an intramolecular vibrational donor-acceptor frequency difference can enhance energy transport. Here, we analyze the extent to which different intramolecular donor-acceptor vibrational frequencies affect excitation energy transport in the natural nonequilibrium steady state configuration. Comments are included on the less physical equilibrium case for comparison with the literature. It is found that for constant Huang-Rhys factors, whereas the acceptor population increases in the equilibrium case when the intramolecular vibrational frequency of the acceptor exceeds that of the donor, this increase is negligible for the nonequilibrium steady state. Therefore, these changes in acceptor population do not significantly enhance energy transport in the nonequilibrium steady state for the natural scenario of incoherent light excitation with biologically relevant parameters of typical photosynthetic complexes. Insight about a potential mechanism to optimize energy transfer in the nonequilibrium steady state based on increasing the harvesting time at the reaction center is analyzed.

Vibrational Energy Landscapes and Energy Flow in GPCRs.

We construct and analyze disconnectivity graphs to provide the first graphical representation of the vibrational energy landscape of a protein, in this study β2AR, a G-protein coupled receptor (GPCR), in active and inactive states. The graphs, which indicate the relative free energy of each residue and the minimum free energy barriers for energy transfer between them, reveal important composition, structural and dynamic properties that mediate the flow of energy. Prolines and glycines, which contribute to GPCR plasticity and function, are identified as bottlenecks to energy transport along the backbone from which alternative pathways for energy transport via nearby noncovalent contacts emerge, seen also in the analysis of first passage time (FPT) distributions presented here. Striking differences between the disconnectivity graphs and FPT distributions for the inactive and active states of β2AR are found where structural and dynamic changes occur upon activation, contributing to allosteric regulation.

Mechano-Responsive Polymers and Nanocomposites: Recent Advances for Self-Adaptive Structural Applications.

Polymer nanocomposites exhibiting remarkable mechanical properties are a focus of research for decades in structural applications. However, their practical application faces challenges due to poor interfacial load transfer, nanofiller dispersion, and processing limitations. These issues are critical in achieving stiff, strong, lightweight, and structurally integrated materials. Additionally, they often suffer from predetermined properties, which may not be effective under specific loading conditions. Addressing these challenges, the development of design strategies for mechano-responsive materials has advanced, enabling self-adaptive properties that respond to various mechanical stimuli. Drawing inspiration from natural systems, these approaches have been implemented in synthetic material systems, leveraging the design flexibility of nanocomposites as needed. Key focus areas include exploring mechanoradical reactions for dynamic mechano-responsiveness, as well as utilizing biomimetic mineralization and mechanical training for self-strengthening. This work also examines multistability, enabling on-demand deformation of materials and structures. Recent advancements in viscoelastic damping and nonreciprocal materials are discussed, highlighting their potential for directional energy absorption, transmission, and vibration control. Despite the need for significant improvements for real-world applications, mechano-responsive polymers and nanocomposites are expected to offer enormous opportunities not only in structural applications but also in other fields such as biomedical engineering, energy harvesting, and soft robotics.

Design and molecular dynamics of biocompatible WPU/PVA composite hydrogels with enhanced fatigue resistance: Energy dissipation of intermolecular clusters for elastomers

To engineer a hydrogel elastomer for use as an in vivo tissue replacement, it is imperative to ensure superior fatigue resistance, guaranteeing a prolonged service life. Investigating the molecular mechanisms of strain energy accumulation and transmission, which occur during the compression of elastomeric materials, is instrumental in elucidating the causes of hydrogel material fatigue. Such insights are of immense value for the development of durable artificial tissue replacements, ensuring their longevity and sustained functionality within the human body. We synthesized hydrogel elastomers through polyvinyl alcohol (PVA) and waterborne polyurethane (WPU) with good biocompatibility, and studied their fatigue behavior through molecular dynamics (MD). The results of this analysis demonstrate that the introduction of energy dissipation structures between mechanically supported molecular frameworks can enhance the relaxation efficiency of polymers. This improvement leads to enhanced resistance of hydrogels to compression fatigue. A total of 1,000,000 cycles of compression tests were conducted to verify that WPU/PVA did not exhibit any significant compression fatigue under high stress of 50 % strain. In contrast, PVA hydrogel exhibited obvious fatigue due to the absence of an energy dissipation structure. These results revealed the source of compression fatigue resistance of hydrogel elasticity and provided powerful guidance for the design and synthesis of artificial tissues.

Study on precipitation in (CoCrFeMnNi)90Al6Ti4 high entropy alloy

(CoCrFeMnNi)90Al6Ti4 high entropy alloy (HEA) was prepared by adding Al and Ti elements into CoCrFeMnNi HEA. The alloy underwent processes including copper mold suction casting, 1473 K homogenization, 30 % cold rolling + 1273 K annealing + 1073 K aging, and water quenching and heating treatment. Microstructure and phase composition of both as-cast and heat-treated (CoCrFeMnNi)90Al6Ti4 HEA were studied using metallographic microscope, scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffractometer (XRD), and transmission electron microscope (TEM). The effect of heat treatment processes on the precipitation of second phases in (CoCrFeMnNi)90Al6Ti4 HEA was investigated, and mechanical properties of as-cast and heat-treated (CoCrFeMnNi)90Al6Ti4 HEA were studied via hardness tests. The results show that in as-cast (CoCrFeMnNi)90Al6Ti4 HEA, the second phase precipitated is primarily L21 structured AlTiNi2 phase. After homogenization, cold rolling, annealing, and aging processes, both the quantity and size of the second phase increase, with a small amount of nanoscale L12 phase appearing after aging treatment. With the progression of heat treatment, the hardness of (CoCrFeMnNi)90Al6Ti4 HEA increases, and mechanical properties are improved.

Define SNP thresholds for delineation of tuberculosis transmissions using whole-genome sequencing.

TB is a chronic disease. Depending on host factors and TB burden, clusters of cases may continue to increase for several years. Conventional genotyping methods overestimate TB transmission, hampering precise detection of outbreaks and comprehensive surveillance. WGS can be used to obtain SNP information of M. tuberculosis to improve discriminative limitations of conventional methods and to strengthen delineation of transmission networks. It is important to define the country-specific SNP thresholds for investigation of transmission. This study demonstrated the use of thresholds of ≤5 and ≤15 SNPs difference between isolates to categorize definite and probable transmission, respectively. Different SNP thresholds should be applied while a higher cutoff was required to define an MDR-TB outbreak. The utilization of SNP thresholds proves to be crucial for guiding public health interventions, eliminating the need for unnecessary public health actions, and potentially uncovering undisclosed TB transmissions.

Sustaining Situational Assessment in Electrical Network Power Control

Objective The aim of this study was to examine contributions to sustained situational assessment over an extended period in the context of electricity transmission control. Background The electricity industry is engaged in a period of unprecedented change in the transition to renewable sources of energy. Changes in the nature and function of electricity transmission risks a reduction in situational assessment as network controllers place increased reliance on advanced technology to identify and diagnose changes in the system state. Method Transmission network controllers from three organisations completed an assessment of their situational assessment on two occasions, one year apart. Results Multiple regression revealed a statistically significant model in which the variance in Year 2 was predicted by a combination of performance in Year 1, the recency of formal training, and the extent to which controllers perceived their job as exciting. No relationship was evident for years of experience as a network controller. Conclusion The results suggest that a combination of recent formal training and perceptions of job excitement may have implications in maintaining the capacity for situational assessment over an extended period in the context of electricity network control. Application The outcomes of the present study suggest that changes in situational assessment can be monitored and that strategies, including formal training and job design, may sustain situational assessment over an extended period in advanced technology settings.

FERC's Troubling Transmission Order No. 1920

The Federal Energy Regulatory Commission (FERC)'s Order No. 1920, issued May 13, 2024, is FERC's latest attempt to craft a nationwide policy to regulate market entry and pricing for the electricity transmission network.1 Approved by a one‐vote margin (2:1) in a short‐staffed Commission, the Order numbers 1,300 pages. In the accompanying dissent and concurring opinion, the three participating Commissioners are unusually critical of each other, in places verging on insulting, with accusations of faulty reasoning, unspoken agendas, basic lapses in logic, and blatant inconsistency with the limits on federal regulatory authority. The 2:1 split continues the evident partisanship apparent in FERC's 2023 orders on natural gas pipeline issues that I wrote about earlier this year.2

Ionization by radiative energy transport vs. impact ionization in energetic atomiccollisions

Abstract We explore a mechanism for ionization in high-velocity (but not yet relativistic) collisions of
light atomic particles, one of which being initially in an excited internal state. This mechanism is
driven by the generalized Breit interaction and proceeeds via radiative energy transport between the colliding
particles which has an extremely long range. The comparison of this mechanism with those, which
are ”standard” for high-velocity collisions, shows that it can play a noticeable role in collisions with
excited target atoms.

Sustainable Maintenance of Conductors in Transmission/Distribution Networks Using Complex Magnetic Field Analysis

This study presents issues related to electromagnetic pollution and the level of magnetic field radiation occurring around conductors used for electricity transmission and distribution. The fact that modeling and simulation are the most efficient methods of optimization, considering the cost–benefit ratio, was the premise of this work. This paper proposes the performance of a complex analysis, carried out in a comparative manner, which includes physical tests and simulations in the existing field around transmission and distribution cables used in transformer substations. In the first stage, the level of the magnetic field existing near the conductor carried by an electric current was tested (measured), and a virtual model was then designed to simulate the field in conditions similar to those of the test. The results obtained from the simulation were analyzed in comparison with those obtained by testing. The maximum permissible limits of exposure to an electromagnetic field, which are regulated by Government Decision HG 520/2016 of 20 July 2016 and Directive 2013/35/EU of the European Parliament and of the Council of 26 June 2013, were used as the reference to formulate conclusions for both situations considered. These comparisons were intended to determine the level of exposure to electromagnetic fields existing in places where electricity transmission/distribution conductors are located. Energy sustainability exists due to the versatile properties of the conductors, with the energy transmission and distribution network being functional regardless of the source of energy production.

Coherent destruction of tunneling of quantum energy transport in a driven nonequilibrium spin-boson model

Coherent destruction of tunneling of quantum energy transport in a driven nonequilibrium spin-boson model

Causes of accidents in electrical distribution networks (using the example of the branch of PJSC Rossetti Volga – Saratov Distribution Networks)

The article is a continuation of a series of studies dedicated to the analysis of power transmission through distribution electric networks of PJSC ROSSETI. The presented material analyzes the functioning of the electrical networks of the branch of PJSC Rosseti Volga – Saratov Distribution Networks. An analytical assessment of the electric energy transport through distribution electric networks was carried out for the period 2018–2022. The structure of the company is considered, the structural characteristics of the main elements of the studied electrical networks are given, and the number of emergencies that occurred during the study period is estimated. A quantitative assessment of the magnitude of the electric energy undersupply caused by power supply interruptions is given. The classification of failures according to the degree of the intensity of undersupply was carried out and a quantitative assessment of each group of failures according to their intensity was made. The influence of the seasonal component on the number of emergencies during the study period is considered. Based on the data from 2022–2023, the analysis of the main causes of damage to the elements of electrical networks was carried out. The classification of failures by groups of failure causes is made, their main characteristics for this period are considered. The percentage ratio of the number of failures number for the most characteristic reasons to the total number of outages during the study period has been established. The information published in the open press was used as the source data. General scientific methods as well as numerical methods of analysis were used in the research. MATLAB graphics editor technologies were used to visualize the obtained analysis results. The results obtained may be of interest to the managers of power grid companies, as well as researchers and engineers engaged in research in the field of reliability of power supply.

A Diagnostic Analysis of the Mechanisms for Arctic Cyclone Intensity Evolution

Abstract The intensity evolution of Arctic cyclones (ACs) is examined via cyclone parameter space and composite analyses based on approximately 18 000 AC tracks during 1979–2021. Cyclone parameter spaces are defined by various parameters representing the cyclone structure and physical processes relevant to cyclone development. It is shown that intensifying ACs are associated with diabatic heating and characterized by a cold core in both the lower and upper troposphere, as well as a thermally asymmetric and vertically tilted structure. In contrast, the decay phase is associated with diabatic cooling and characterized by a vertically aligned cyclone with reduced horizontal asymmetry. The cyclone parameter space analysis also indicates a warm core in the lower troposphere for a subset of ACs, which may reflect a frontal occlusion. The transition from AC intensification to decay, on average, is marked by a sharp decrease in both upward motion and diabatic heating, along with the vertical alignment of the cyclone structure. Following this transition, an upright cyclone may persist for a long time due to the weak background vertical wind shear, diabatic cooling, and weak Rossby wave energy dispersion. The evolution of ACs can thus be regarded as a two-stage process: a baroclinic development stage aided by diabatic heating, during which the AC evolution may conform with the Norwegian model for midlatitude cyclones, and a slow decay stage of an equivalent barotropic cyclone, which may leave a remnant tropopause polar vortex after the erosion of the surface circulation. Significance Statement Arctic cyclones are the primary weather system in the Arctic and are also an important component in the Arctic climate system owing to their role in modulating Arctic sea ice variability and poleward moisture and energy transport. We examined the cyclone structural characteristics and physical processes associated with the Arctic cyclone intensity evolution and proposed a two-stage conceptual model. A better understanding of the Arctic cyclone intensity change mechanisms will help us better anticipate the changes in Arctic cyclone activity in a warmer climate.

Exploring distance-based wireless transceiver placements for wireless network-on-chip architecture with deterministic routing algorithms

Network-on-chip (NoC) technology is crucial for integrating multiple embed-ded computing cores onto a single chip. Consequently, this has led to the de-velopment of the wireless network-on-chip (WiNoC) concept, seen as a promis-ing strategy to overcome scalability issues in communication systems withinchips for future many-core architectures. This research analyses the impactof wireless transceiver subnet clustering on the hundred-core mesh-structuredWiNoC architecture. The study aims to examine the effects of distance-basedwireless transceiver placements on the transmission delay, network throughput,and energy consumption within a mesh wireless NoC architecture featuring ahundred cores, under specific routing strategies: X-Y, west-first, negative-first,and north-last. This research investigates the impact of positioning radio sub-nets at the farthest, farther, nearest, and closest positions within an architectureequipped with four wireless transceivers. The Noxim simulator was utilised tosimulate the analysed wireless transceiver placements within the hundred-coremesh-structured WiNoC designs, with the objective of validating the results.The architecture with the wireless transceivers positioned at midway proxim-ity (nearer and further) demonstrated the best performance, as evidenced by thelowest latencies for all evaluated deterministic routing algorithms, according tothe simulation outcomes.

Experimental and numerical investigations with multifunctional heat transfer fluid to evaluate the performance of a thermal energy storage system

In the upcoming decades, concentrated solar power (CSP) technology is expected to be one of the most promising methods of producing electricity.Along with the reduction in energy waste coupled with an increase in efficiency, the thermal energy storage (TES) systems are vital in refining the dependability and efficacy of the energy infrastructure and in reducing gap between supply and demand. This study aims to evaluate a parabolic trough collector by means of experimental investigation and mathematical modelling. Nanofluid is employed as an energy absorption material and transport medium from concentrating tube to storage tank. At consistent flow rate of 3.0 L per minute, a comparative evaluation is conducted between water and ZnS/ water-quantum dots at different volume concentrations (0.1, 0.2, 0.3, and 0.4 %). Heat exchanger-delivered sensible heat, thermal efficiency, heat removal factor, and energetic efficiency are used to examine the qualitative and quantitative performance of the system. The ZnS/ water-quantum dots ratio of 0.3 % (wt%) has been found to yield the maximum thermal and energetic efficiencies. At a solar intensity of 1210 W/m2, the highest thermal efficiency of 57.81 % is reflected by the experimental observations. At the same intensity, there is a 20.63 % increase in the energy efficiency. The charge and discharge of phase-changing material (PCM) are highly influenced by the flow rate of heat transfer fluid (HTF). By increasing the HTF flow rate from 1 to 3 L per minute, the solidification and melting times are shortened by 30 % and 10 %, respectively. This study emphatically reflects a high potential of employing nanofluid in TES to enhance the performance of energy infrastructure coupled with energy waste reduction.

Application of molecular epidemiology in revealing HIV-1 transmission network and recombination patterns in Tianjin, China.

Using a comprehensive molecular epidemiological approach, we characterized the transmission dynamics of HIV-1 among the MSM population in Tianjin, China. Our findings revealed that 38.56% (386/1001) of individuals clustered across 109 molecular transmission clusters (TCs), with MSM aged 50 and below being the group most commonly transmitting HIV-1. Among the identified TCs, CRF01_AE predominated, followed by CRF07_BC. Notably, CRF07_BC demonstrated a higher propensity for forming large clusters compared to CRF01_AE. Birth-death skyline analyses of the two largest clusters indicated that the HIV/AIDS transmission may be at a critical point, nearly all had Re approximately 1 by now. A retrospective analysis revealed that the rapid expansion of these large clusters was primarily driven by the introduction of viruses in 2021, highlighting the crucial importance of continuous molecular surveillance in identifying newly emerging high-risk transmission chains and adapting measures to address evolving epidemic dynamics. Furthermore, we detected the transmission of drug-resistant mutations (DRMs) within the TCs, particularly in the CRF07_BC clusters (K103N, Y181C, and K101E) and CRF01_AE clusters (P225H and K219R), emphasizing the importance of monitoring to support the continued efficacy of first-line therapies and pre-exposure prophylaxis (PrEP). Recombination analyses indicated that complex recombinant patterns, associated with increased amino acid variability, could confer adaptive traits to the viruses, potentially providing a competitive advantage in certain host populations or regions. Our study highlights the potential of integrating molecular epidemiological and phylodynamic approaches to inform targeted interventions.

Distributed Dynamic Event-Triggered Leader-Following Consensus for Nonlinear Multiagent Systems Over Fading Channel.

This article investigates the leader-following consensus problem of discrete-time nonlinear multiagent systems (MASs) over fading channels. With the consideration of the transmission among followers maybe affected by the fading networks, the nonidentical fading channels model is constructed. To reduce the transmission network burden, the dynamical event-triggered mechanism (DETM) is developed. Different from most of existing event-triggered strategies, the threshold parameter in the developed dynamical event-triggering condition is dynamically adjusted according to a dynamic rule. Based on the DETM, a distributed consensus control protocol is designed under fading channels. Then, sufficient criteria are provided to ensure that MASs can achieve the leaser-following consensus, and satisfy the H∞ performance index in the presence of fading channels. The desired controller parameters can be derived in terms of solutions of matrix inequalities that are lightly solvable. In the end, simulation results show that the designed dynamical event transmission policy is capable of diminishing communication burden more promptly and effectively than some existing ones.

Averaged flow in a rotating flat layer at librations

Abstract One of the important areas in fluid mechanics is thermal convection; its study is an urgent task from the point of view of effective control of heat and mass transfer. With increasing energy consumption worldwide, improved energy transfer methods are required. Various complicating factors can either strengthen or weaken energy transport mechanisms. In the current work, attention is paid to the libration effect as one of the effective ways to control heat transfer in a rotating cavity. The experiments are aimed at a study of convective flows generated in a flat layer unevenly rotating around a horizontal axis. The flat boundaries are kept at different temperatures. It is found that the cavity librations noticeably intensify the heat transfer in a layer. The flow structure obtained using the PIV method for the cases of uniform and non-uniform rotation of the cavity is presented for the first time. The effectiveness of librations for the intensifying heat and mass transfer in a rotating hydrodynamic system is shown.

Vertical Cavity Surface Emitting Laser technology: A comprehensive review

Vertical Cavity Surface Emitting Laser (VCSEL) technology has become an indispensable element in optical communication systems and optoelectronics due to its many advantages, and the unique characteristics of VCSELs, including vertical emission, high-speed operation, and low power consumption, have attracted much interest from researchers and industry professionals. This paper provides a comprehensive overview of VCSELs, explaining their basic principles and two commonly used structures. It also delves into the field of optical communications, highlighting the challenges faced in the current development, from which it introduces the significant progress made by VCSELs over the past decade in various applications such as high-speed data transmission, multi-mode communications, and long-distance networks. In addition, this study provides valuable insights into the future trajectory and potential evolution of VCSEL technology to facilitate further research and innovation in the field of communications. By providing a holistic analysis, this study is a valuable resource for scientists and researchers to help them realize the full potential of VCSELs in advancing optical communication technologies to meet the ever-changing needs of modern communication networks.

Phylogenetic Network Analyses Reveal the Influence of Transmission Clustering on the Spread of HIV Drug Resistance in Quebec from 2002 to 2022

Background: HIV drug resistance (HIV-DR) may jeopardize the benefit of antiretroviral therapy (ART) in treatment and prevention. This study utilized viral phylogenetics to resolve the influence of transmission networks on sustaining the spread of HIV-DR in Quebec spanning 2002 to 2022. Methods: Time trends in acquired (ADR) and transmitted drug resistance (TDR) were delineated in treatment-experienced (n = 3500) and ART-naïve persons (n = 6011) with subtype B infections. Similarly, non-B-subtype HIV-DR networks were assessed pre- (n = 1577) and post-ART experience (n = 488). Risks of acquisition of resistance-associated mutations (RAMs) were related to clustering using 1, 2–5, vs. 6+ members per cluster as categorical variables. Results: Despite steady declines in treatment failure and ADR since 2007, rates of TDR among newly infected, ART-naive persons remained at 14% spanning the 2007–2011, 2012–2016, and 2017–2022 periods. Notably, half of new infections among men having sex with men and heterosexual groups were linked in large, clustered networks having a median of 35 (14–73 IQR) and 16 (9–26 IQR) members per cluster, respectively. Cluster membership and size were implicated in forward transmission of non-nucleoside reverse transcriptase inhibitor NNRTI RAMs (9%) and thymidine analogue mutations (TAMs) (5%). In contrast, transmission of M184V, K65R, and integrase inhibitors (1–2%) remained rare. Levels of TDR reflected viral replicative fitness. The median baseline viremia in ART-naïve groups having no RAMs, NNRTI RAMs, TAMs, and M184VI were 46.088, 38,447, 20,330, and 6811 copies/mL, respectively (p < 0.0001). Conclusion: Phylogenetics emphasize the need to prioritize ART and pre-exposure prophylaxis strategies to avert the expansion of transmission cascades of HIV-DR.