Decrease In Frequency Research Articles

Effects of interlayer SiO2 or Au on the performances of LNOS-SAW

Abstract Surface acoustic wave (SAW) resonators and filters based on lithium niobate (LN) or lithium tantalate crystals have been widely used in modern wireless communication systems. However, acoustic energy in these kinds of devices is lost in the substrate due to longitudinal attenuation. The enhancements of quality factor and coupling coefficient are still in demand for further applications. This work proposes a SAW based on LN thin film on a sapphire substrate (LNOS). Besides, we explored the effects of using different bonding materials on the LNOS-SAW performances. The presence of the interlayer not only plays a role in bonding but also has an impact on the performance of the resonator. Considering the compatibility of the process in this method, 2 μm-thick silicon dioxide (SiO2) or 1 μm-thick gold (Au) is designed as the interlayer. As the displacement diagrams show, the acoustic energy of the SAW with interlayer is reflected at the interface, and the energy leakage is suppressed. The simulation results show that the presence of SiO2 or Au causes a decrease in resonant frequencies of the resonators, and the effect is more pronounced with Au. Significantly, the presence of SiO2 enhances the coupling efficiency of the resonator while the Au interlayer brings a more obvious improvement in the quality factor.

Flow and heat transfer in multi-cavity pistons with oscillating cooling

Under high temperature and pressure conditions, pistons play a crucial role in managing thermal stress within combustion chambers. To analyze of the heat transfer characteristics of piston cooling systems in low-speed engines, this study developed and validated an oscillating cooling model featuring a composite piston with multiple cooling cavities. Using numerical simulation methods combined with dynamic mesh technology, the model replicates the long-stroke behavior of actual diesel engines and is validated against preliminary experimental data. The results demonstrates that during reciprocating motion, oil flowing through the telescopic sleeve interacts with gas from breather holes, forming a gas–liquid two-phase flow that significantly alters the liquid film coverage ratio (LFC) on wall surfaces, influencing heat transfer efficiency. As the filling rate increases from 28 % to 71 %, the average liquid film coverage (ALFC) rises by 0.27, and LFC fluctuation frequency decreases, with amplitude increasing by 0.08. Notably, the average Nusselt number (Nuavg) shows significant increases for top surface of inner cavity (TSIC) and side surface of inner cavity (SSIC) between filling rates of 52 % and 64 %, while the maximum increase for top surface of outer cavity (TSOC) and side surface of outer cavity (SSOC) occurs between 37 % and 52 %. Temperature drops at points A and B in the filling rate range of 28 % to 52 % were 1.37 K (4.09 K), which is notably higher than the 0.35 K (0.86 K) drop in the 52 % to 71 % range. Analyzing these changes indicates that the optimal filling rate for enhanced heat transfer performance is approximately 52 %. Furthermore, as engine speed increases from 135.2 to 202.8 rpm, the piston head filling rate decreases from 0.60 to 0.46, reducing both the contact area and the surface heat transfer coefficient. This study provides profound insights of the multiple cooling cavities under reciprocating motion and presents new strategies for optimizing piston cooling systems designed for low-speed engines.

Properties of a continuous optical discharge sustained by short-wave infrared laser radiation in high pressure argon

Abstract The paper is devoted to the experimental study of the characteristics of continuous optical discharge (COD) sustained by high power continuous wave laser radiation at a wavelength λ = 1.08 μm in high pressure argon. New data on COD threshold laser power dependence on argon pressure in the range 20-50 bar are obtained. COD threshold laser power is shown to be in good agreement with the data obtained by other authors and theoretical evaluations provided the contribution of plasma energy loss due thermal radiation is taken into account properly. A study of the convective plume oscillations around COD in argon has been carried out. It was found that in a pressure range 25-35 bar the growth of the laser radiation power leads to a decrease in convection oscillation frequency from 33 to 29 Hz, while the radius of the convective plume grows accordingly. The oscillation frequency ν and characteristic radius of the convective plume r0 were found to obey the similarity relation previously established in experiments with COD in xenon.

Dynamic causal modelling highlights the importance of decreased self-inhibition of the sensorimotor cortex in motor fatigability.

Motor fatigability emerges when challenging motor tasks must be maintained over an extended period of time. It is frequently observed in everyday life and affects patients as well as healthy individuals. Motor fatigability can be measured using simple tasks like finger tapping at maximum speed for 30s. This typically results in a rapid decrease of tapping frequency, a phenomenon called motor slowing. In a previous study (Bächinger et al, eLife, 8 (September), https://doi.org/10.7554/eLife.46750 , 2019), we showed that motor slowing goes hand in hand with a gradual increase in blood oxygen level dependent signal in the primary sensorimotor cortex (SM1), supplementary motor area (SMA), and dorsal premotor cortex (PMd). It is unclear what drives the activity increase in SM1 caused by motor slowing and whether motor fatigability affects the dynamic interactions between SM1, SMA, and PMd. Here, we performed dynamic causal modelling (DCM) on data of 24 healthy young participants collected during functional magnetic resonance imaging to answer this question. The regions of interest (ROI) were defined based on the peak activation within SM1, SMA, and PMd. The model space consisted of bilateral connections between all ROI, with intrinsic self-modulation as inhibitory, and driving inputs set to premotor areas. Our findings revealed that motor slowing was associated with a significant reduction in SM1 self-inhibition, as uncovered by testing the maximum à posteriori against 0 (t(23)=-4.51, p < 0.001). Additionally, the model revealed a significant decrease in the driving input to premotor areas (t(23) > 2.71, p < 0.05) suggesting that structures other than cortical motor areas may contribute to motor fatigability.

Fallopian tube rheology regulates epithelial cell differentiation and function to enhance cilia formation and coordination

The rheological properties of the extracellular fluid in the female reproductive tract vary spatiotemporally, however, the effect on the behaviour of epithelial cells that line the tract is unexplored. Here, we reveal that epithelial cells respond to the elevated viscosity of culture media by modulating their development and functionality to enhance cilia formation and coordination. Specifically, ciliation increases by 4-fold and cilia beating frequency decreases by 30% when cells are cultured at 100 mPa·s. Further, cilia manifest a coordinated beating pattern that can facilitate the formation of metachronal waves. At the cellular level, viscous loading activates the TRPV4 channel in the epithelial cells to increase intracellular Ca2+, subsequently decreasing the mitochondrial membrane potential level for ATP production to maintain cell viability and function. Our findings provide additional insights into the role of elevated tubal fluid viscosity in promoting ciliation and coordinating their beating—a potential mechanism to facilitate the transport of egg and embryo, suggesting possible therapeutic opportunities for infertility treatment.

Divergent Immediate and Delayed Effects of Juvenile Exposure to Doxorubicin on the Thymus in C57BL/6 Mice.

The understanding of alterations within the immune system following doxorubicin (DOX) chemotherapy, and subsequent restoration, in childhood cancer survivors remains limited. This investigation endeavors to elucidate the immediate and delayed changes in thymic immune cell populations and their phenotypes in response to clinically relevant low doses of DOX in a juvenile mouse model. Male mice underwent a regimen of repeated low-dose DOX intraperitoneal injections at 4 mg/kg/week for three consecutive weeks. One week after the last dose of DOX, a subset of mice was euthanized to assess the immediate effects of DOX administration. A second subset of mice was euthanized five weeks after the last DOX dose to evaluate the delayed effects. Thymic samples were collected for multiparameter flow cytometry analysis to evaluate alterations in immune cell composition and phenotype. Additionally, quantitative real-time polymerase chain reaction (qRT-PCR) was employed to measure gene expression of- cytokines and senescence markers. One week following DOX administration, DOX treatment resulted in significant decline in thymus weight, with notable alterations in immune cell subpopulations. Reduced frequencies of mature CD3+CD4+ and CD3+CD8+ T cells were observed, along with changes in proliferation and exhaustion markers. Gene expression analysis revealed upregulation of Foxn, Pax1, Ifnγ, and Il7 alongside decreased Il6 and Il17 expression. Furthermore, Cdkn1a (p21Cip1) expression was elevated, suggesting immunosenescence. Five weeks following DOX administration, delayed effects of DOX treatment manifested in rebound increase in thymus weight and altered frequencies of CD4+ and CD8+ T cell subsets, with distinct patterns of proliferation and exhaustion observed. Notably, central memory CD4+ T cells exhibited significant decrease in frequency, while naive and effector memory CD4+ T cells showed reduced proliferation (Ki67+) and PD1 expression. Similar trends were observed in CD8+ T cell subsets, indicating selective effects of DOX on T cell differentiation and function. Although expression of thymus-related genes was normalized, p21Cip1 gene expression remained elevated. DOX treatment elicits a multifaceted influence on immune cell subsets and thymic weight. Immediate effects included thymic atrophy and reductions in mature T cell populations, while delayed effects showed rebound thymic hyperplasia and selective changes in CD4+ and CD8+ T cell subsets. Notably, both central memory and effector memory T cells exhibited reduced proliferation and exhaustion, suggesting unique impacts of DOX on immune cell function. The enduring elevation in p21Cip1 gene expression 5 weeks after DOX treatment suggests an immunosenescent phenotype. These observations collectively illuminate the formidable task of preserving immune competence and overall well-being in childhood cancer survivors subjected to DOX therapy.

Neuronal rhythmicity and cortical arousal in a mouse model of absence epilepsy

Objectives: Absence seizures impair psychosocial function, yet their detailed neuronal basis remains unknown. Recent work in a rat model suggests that cortical arousal state changes prior to seizures and that single neurons show diverse firing patterns during seizures. Our aim was to extend these investigations to a mouse model with studies of neuronal activity and arousal state to facilitate future fundamental investigations of absence epilepsy.Methods: We performed in vivo extracellular single unit recordings on awake head-fixed C3H/HeJ mice. Mice were implanted with tripolar electrodes for cortical electroencephalography (EEG). Extracellular single unit recordings were obtained with glass micropipettes in the somatosensory barrel cortex, while animals ambulated freely on a running wheel. Signals were digitized and analyzed during seizures and at baseline.Results: Neuronal activity was recorded from 36 cortical neurons in 19 mice while EEG showed characteristic 7–8 Hz spike-wave discharges. Different single neurons showed distinct firing patterns during seizures, but the overall mean population neuronal firing rate during seizures was no different from pre-seizure baseline. However, the rhythmicity of neuronal firing during seizures was significantly increased (p < 0.001). In addition, beginning 10s prior to seizure initiation, we observed a progressive decrease in cortical high frequency (>40 Hz) EEG and an increase in lower frequency (1–39 Hz) activity suggesting decreased arousal state.Significance: We found that the awake head-fixed C3H/HeJ mouse model demonstrated rhythmic neuronal firing during seizures, and a decreased cortical arousal state prior to seizure onset. Unlike the rat model we did not observe an overall decrease in neuronal firing during seizures. Similarities and differences across species strengthen the ability to investigate fundamental key mechanisms. Future work in the mouse model will identify the molecular basis of neurons with different firing patterns, their role in seizure initiation and behavioral deficits, with ultimate translation to human absence epilepsy.

Lymphocyte subsets in epicardial, thymic and subcutaneous adipose tissue during advanced coronary atherosclerosis in patients with coronary artery disease

The important role of epicardial (EAT) and thymic (TAT) adipose tissue in the development of atherosclerosis in patients with coronary artery disease (CAD) is widely discussed. The purpose of the study was to investigate the lymphocyte subsets and FoxP3+Treg lymphocytes in epicardial, thymic and subcutaneous adipose tissue depending on the severity of coronary atherosclerosis in patients with chronic CAD. We examined 24 patients with CAD (21 men; mean age 65.0 (58.0-68.0) years) scheduled for open-heart surgery. In samples of EAT, TAT and subcutaneous adipose tissue (SAT), the content of CD4+, CD8+, B lymphocytes, NK and NKT cells, CD4+CD25hiFoxP3+ and CD4+CD25lowFoxP3+T regulatory lymphocytes (Treg) and a proportion of Tregs with FoxP3 nuclear translocation was determined by imaging flow cytometry. Depending on the severity of atherosclerosis, assessed according to Gensini Score, patients were divided into groups: group 1 – patients with Gensini Score 65; group 2 – patients with Gensini Score ≥ 65. Patients in group 2 had higher frequency of EAT CD4+CD25lowTreg with FoxP3nuclear translocation, TAT CD8+T lymphocytes and NK cells, a lower content of TAT double positive CD4+CD8+T lymphocytes, and a tendency towards a decrease of frequency of TAT CD4+CD25hiTreg with FoxP3 nuclear translocation compared to patients in group 1. The level of nuclear translocation of FoxP3 in CD4+CD25hiTreg cells in TAT was inversely related to the proportion of CD8+T lymphocytes (rs = -0.653; p = 0.012) and NK cells (rs = -0.723; p = 0.003) in TAT, and directly – to the proportion of double positive CD4+CD8+T lymphocytes in TAT (rs = 0.567; p = 0.034) and the value of the waist-to-hip ratio (rs = -0.474; p = 0.041). Further research is required to study the molecular mechanisms of these relationships in patients with coronary atherosclerosis and chronic coronary artery disease.

Effect of UEVC parameters on cutting surface quality and subsurface damage of single crystal γ-TiAl alloy via atomic simulation

TiAl alloys are favored by the aerospace industry due to its excellent mechanical properties. However, its intrinsic brittleness, the use of conventional cutting (CC) process leads to the problems of high cutting force and high cutting temperature, which in turn affects the machined surface quality. Ultrasonic elliptical vibratory cutting (UEVC) has been proved to be an effective method to improve the surface quality and reduce the subsurface damage of difficult-to-machine materials. This paper compares the effects of CC and UEVC processes on cutting forces and subsurface damage based on molecular dynamics simulation methods, and the effects of elliptical vibration frequencies and amplitude ratios (AR) on surface morphology, roughness, and subsurface damage are investigated. The results show that the cutting force and subsurface damage in the UEVC process are reduced compared with that in the CC. Due to the vibration frequency, the subsurface damage is mainly dominated by atomic clusters, and both surface and subsurface masses show an optimization trend as the vibration frequency decreases. In terms of the AR, the surface quality is better at an AR of 2/3, with less activation of immovable dislocations, and the degree of subsurface damage decreases as the AR increases, and a relatively stable defective structure emerges when the AR is 1/2. The simulation results facilitate an atomic-scale comprehension of the removal mechanism of UEVC and further provide a theoretical foundation for the surface mass and subsurface damage mechanism and optimization of vibrational parameters of UEVC single crystal γ-TiAl alloy.

An inerter-enhanced bistable nonlinear energy sink for seismic response control of building structures

Structural control strategies have attracted great attention in reducing unwanted structural responses. To mitigate the vibrations of seismically excited buildings, this paper proposes a novel vibration control device: an inerter-enhanced bistable nonlinear energy sink (BNESI). A three-story building structure is selected as an example, where the BNESI is attached to the top of the structure and linked to the top second floor of the structure, to explore the control effect of the device under earthquakes. The restoring force of the BNESI and equations of motion for the BNESI-controlled system are derived first. Subsequently, a multi-objective optimization design method of the BNESI is proposed and applied in building structures. The input energy robustness of the BNESI is then accessed by various initial velocities subjected to the structures. Moreover, the seismic vibration mitigation capacity of the BNESI is systematically investigated under a group of near-field and far-field excitations. Analysis results show that the proposed design algorithm for BNESI can be an attractive alternative to effectively obtain optimal parameters of the control device. The BNESI is less sensitive to the input energy levels, and can stably capture and dissipate energy from the primary structure. Also, the BNESI system provides good control effectiveness with less sensitivity to the uncertainty of seismic excitations. In addition, with less standard deviation, the damper stroke of the BNESI is only about a quarter of that of the TMD under the same excitation. Moreover, the damage to the primary structure has a negligible effect on the control effect of the BNESI system. Meanwhile, the BNESI can decrease the energy dissipation demand on the structure, and the energy distribution mode of the BNESI system shows less sensitivity to the frequency decrease of the structure.

Evaluating impact damage on carbon fiber-reinforced polymer plates utilizing zero-group-velocity Lamb waves

This paper presents an effective method for evaluating the impact damage of composite plates using zero-group-velocity (ZGV) Lamb waves. A finite element (FE) model of the carbon fiber-reinforced polymer (CFRP) plate is established to analyze in detail the propagation characteristics of the S1-ZGV Lamb wave mode with a specified propagation direction. The study investigates the changes in the S1-ZGV mode with varying damage levels, characterized by a decrease in elastic moduli. Results indicate that as the damage level increases, the corresponding S1-ZGV frequency and amplitude decrease proportionally. The spectral amplitude (SA) at the initial S1-ZGV frequency exhibits a consistent and significant decrease with increasing damage levels, offering a reliable method for accurately assessing damage in CFRP plates. Additionally, the S1-ZGV mode of the CFRP plate is experimentally excited using the pitch-catch technique with air-coupled ultrasonic transducers to explore the variations in the S1-ZGV mode with different impact damages. Experimental findings show that the SA of the S1-ZGV mode at the initial S1-ZGV frequency decreases monotonically and sensitively with an increasing number of impacts. These experimental results correlate with the FE analysis, validating the effectiveness of accurately evaluating impact damage in CFRP plates based on the SA of S1-ZGV modes.

Shaking table tests on concrete blocks anchored at the bottom of hydrogen storage vessels considering field installation conditions

ABSTRACT In this study, a scale model was created based on field investigation and design standards to evaluate the structural safety of a vertical hydrogen storage vessel stored in gas and liquid form during an earthquake, and a shaking table test was performed. Through testing, it was recognized that fixed anchors were also vulnerable to earthquakes, and additional seismic performance tests were conducted. In Set 1, where gas was stored, no damaged areas were observed during the maximum input seismic motion (EQ 200 %). In Set 2, where liquid was stored, cracks began to appear between the concrete block and the foundation at EQ 100 %, corresponding to the seismic design standard, and progressed to complete destruction at EQ 150 %. Cracks between the concrete block and the foundation led to a decrease in resonant frequency, accompanied by an amplification in acceleration. A reduction in resonant frequency by more than 15 % is anticipated to result in severe damage to the substructure, indicating a potential for brittle failure due to concrete damage prior to anchor failure. The anchors exhibited residual loads of over 80 % of the design load on average, confirming the use of anchors meeting seismic performance requirements.

Catalytic activity of chitinase encapsulated with alginate and its application in a biosensor for postharvest fungal detection

This research aimed to preserve the chitinase catalytic activity using alginate and zinc oxide nanoparticles (ZnO-NPs), to evaluate its thermal stability at 37 ºC, 50 ºC, and 70 ºC and its ability to detect Rhizopus stolonifer, Colletotrichum fragariae, and Alternaria alternata in a capacitive transducer-based biosensor. The ZnO-NPs measured less than 100 nm. The phosphate buffer-citric acid was a better solvent than water. Al+ZnONPs Ch showed the highest thermal stability at 37 ºC and 50 ºC (2 IU) for 45 d. Conversely, the free enzyme lost its activity from day 1–28 at 37 ºC (3.3 IU-2.8 IU), and alginate-encapsulated chitinase (AlCh) had the lowest activity at 50 ºC during 45 d (1.3 IU). Chitinase, alginate, and the ZnO-NPs were confirmed for FTIR spectra. The Al+ZnONPs Ch had the best response in the biosensor, observing a decrease in electrical frequency when the concentration of the tested fungi increased (106 spores mL−1 =100–250 kHz and 104 spores mL−1 = 400 kHz). In conclusion, at 37 ºC and 50 ºC, the chitinase had a stable catalytic activity compared to the remaining treatments, and it could be used to detect fungi in a biosensor at concentrations from 103 to 106 spores mL−1.

Anisotropic phonon dynamics in Dirac semimetal PtTe2 thin films enabled by helicity-dependent ultrafast light excitation

Coherent phonons have aroused considerable attention in condensed matter physics owing to their extraordinary capacity of reflecting and controlling the physical properties of matter. However, the investigation on the interaction between coherent phonons and other microscopic particles on the ultrafast timescale within topological systems continues to be an active and unresolved area. Here, we show the energy transfer of coherent optical phonons (COP) in Dirac semimetal PtTe2 thin films using ultrafast optical pump-probe spectroscopy. Specifically, the helicity-dependent light-driven anisotropic COP signals disclose their direct connection with the light-excited anisotropic spin-polarized electrons via an angular momentum transfer. Furthermore, we observe the notable decreases in the COP oscillation frequency and the decay rate with increasing temperatures due to the anharmonic phonon-phonon scattering and electron-phonon scattering in the COP dissipation process, respectively. Our work paves the way for uncovering the coherent phonons in Dirac semimetals for the potential applications in optoelectronics and opto-spintronics.

The Influence of ENSO Diversity on Future Atlantic Tropical Cyclone Activity

Abstract El Niño–Southern Oscillation (ENSO) influences seasonal Atlantic tropical cyclone (TC) activity by impacting environmental conditions important for TC genesis. However, the influence of future climate change on the teleconnection between ENSO and Atlantic TCs is uncertain, as climate change is expected to impact both ENSO and the mean climate state. We used the Weather Research and Forecasting Model on a tropical channel domain to simulate 5-member ensembles of Atlantic TC seasons in historical and future climates under different ENSO conditions. Experiments were forced with idealized sea surface temperature configurations based on the Community Earth System Model (CESM) Large Ensemble representing: a monthly varying climatology, eastern Pacific El Niño, central Pacific El Niño, and La Niña. The historical simulations produced fewer Atlantic TCs during eastern Pacific El Niño compared to central Pacific El Niño, consistent with observations and other modeling studies. For each ENSO state, the future simulations produced a similar teleconnection with Atlantic TCs as in the historical simulations. Specifically, La Niña continues to enhance Atlantic TC activity, and El Niño continues to suppress Atlantic TCs, with greater suppression during eastern Pacific El Niño compared to central Pacific El Niño. In addition, we found a decrease in the Atlantic TC frequency in the future relative to historical regardless of ENSO state, which was associated with a future increase in northern tropical Atlantic vertical wind shear and a future decrease in the zonal tropical Pacific sea surface temperature (SST) gradient, corresponding to a more El Niño–like mean climate state. Our results indicate that ENSO will remain useful for seasonal Atlantic TC prediction in the future.

Carbon nanoparticle exposure strengthens water-relation parameters by stimulating abscisic acid pathway and aquaporins genes in rice

Mechanism of action and molecular basis of positive growth effects including yield increase due to carbon nanoparticle (CNP) treatment in rice plants is dissected here. CNP at 500 -750 µg/mL were found to be the optimum dosages showing best seedling growth. CNP treatment resulted increase in stomata size, stomatal conductance and water use efficiency along with low relative humidity, decrease in stomata frequency and internal CO2 concentration. CNP-coupled with water uptake was found to be endocytosis mediated, although CNP uptake was not affected by endocytosis inhibitor application in roots. Genomic analysis resulted major involvement of ABA pathway and stomata size and frequency genes in Arabidopsis and rice. Elevated endogenous ABA in rice seedlings and flag leaves along with increased expression of ABA biosynthetic genes in Arabidopsis and rice AtNCED3, AtNCED6, OsNCED1 confirmed increased ABA synthesis. Negative regulators of ABA pathway, OsSNRK2 down-regulation and up-regulation of stomagen (OsEPFL9) reconfirmed ABA's involvement. CNP treatment exerted cold tolerance in seedlings and water stress tolerance in reproductive stage. CNP treatment under water withheld condition resulted water stress tolerance by maintaining lower stomatal conductance, transpiration rate and higher relative water content. Increased ABA (OsSNRK1, OsSNRK2) and aquaporin (OsPIP2–5 and OsPIP1–3) genes’ expressions could explain the better water stress tolerance in rice plants treated with CNP. Altogether, due to thermomorphogenesis, down-regulation of Phytochrome B transcript resulted altered the ABA pathway and stomatal distribution with size (Graphical Abstract). These changes resulted improved water relation parameters and water use efficiency (WUE) showing improvement in yield. Detailed mechanism of action of CNP in abiotic stress tolerance can be exploited using nano-agriculture at field level.

Operational Dynamic Load Testing for Repair Recommendations Case Study of Access Road to Vehicle Weight in Motion

The indication of inaccuracies in vehicle weight measurement using Weight in Motion (WIM) technology on mining roads has been identified due to the non-fulfillment of the design criteria required by the WIM manufacturer. This study aims to identify the gap between the actual pavement conditions and the design criteria and to design improvements to eliminate this gap. The method employed involves dynamic load testing, followed by processing the test data with operational modal analysis (OMA) to obtain dynamic parameters that will serve as a reference for calculating the pavement capacity. From OMA, a natural structural frequency of 26.342 Hz was obtained, while the theoretical calculation based on the design criteria was 29.481 Hz. This frequency decrease indicates structural damage of 10.65% and a capacity reduction of 26.8% from the design criteria. This finding is reinforced by a critical damping ratio of 5.25%, which is higher than the damping for intact concrete, ranging between 2%-5%. This indicates energy dissipation through concrete cracks. It is recommended to inject the cracks in the existing pavement with a cement base and perform a 130 mm overlay with mortar grout (fc’= 50 MPa) with one layer of M12 wire mesh. The connection with the old pavement will use concrete bonding and D13-600/600 chemical anchors. With this improvement, the structural capacity will become 104% of the design criteria.

Deciphering split ring resonators: understanding theoretical validation and simulation implications

This study presents a comparative analysis of analytical calculations and simulation results of a single-ring split ring resonator (SRR). A simulated SRR made of aluminum, designed in high frequency structure simulator (HFSS), with the resonant frequency of 3.97 GHz with transmission loss of −47.7 dB. The initial gap, width, and thickness of the ring are set at 1 mm, 1 mm, and 3 mm, respectively. These geometrical parameters are subsequently varied in simulations, and theoretical calculations are conducted for each variation using Python 3.10 code to facilitate comparative analysis. The analytical calculations reveal certain limitations in accurately modeling the impact of fringing and radiation, particularly when dealing with smaller dimensions. Although there exist slight disparities between the simulated and calculated outcomes, it is evident that the theoretically derived results exhibit a close correspondence with simulated responses, particularly for dimensions that are not excessively small. This observation underscores the confirmation that an augmentation in the gap of the Split Ring Resonator (SRR) leads to an elevation in the resonant frequency. Furthermore, by maintaining a constant inner radius and adjusting the outer radius to modulate the width of the SRR, a decrease in the resonant frequency is noted with an increase in the width of the metallic ring. Similarly, an increase in the thickness of the ring contributes to a reduction in the resonant frequency This comprehensive investigation provides a valuable methodology for corroborating theoretically derived results with simulation data. Additionally, the research underscores the diverse resonances that can be achieved by fine-tuning the gap, width, and thickness of the split ring resonator, highlighting the significance of selecting these dimensions carefully to attain specific resonant frequencies.

Nonlinear Dynamic Analysis of High-Strength Concrete Bridges under Post-Fire Earthquakes Considering Hydrodynamic Effects

This study employed the linear interpolation method to ascertain the curve relationship between the elastic modulus and stress of high-strength concrete C60 with temperature, and the nonlinear dynamic analysis of high-strength concrete bridge structures subjected to post-fire earthquake action at varying water levels was subsequently evaluated. It was established that both the hydrodynamic effects and the temperature effects have a considerable impact on the structural dynamic response of bridges. The presence of water has been observed to increase the dynamic response of pier structures. At water levels of 0 m and 10 m, the temperature effect results in a reduction in the fundamental frequencies of acceleration and displacement responses by 73.68% and a decrease in the fundamental frequency of stress responses by 83.33%. At a water level of 20 m, the fundamental frequencies of the acceleration, displacement, and stress responses decrease by 53.49%. In consideration of the acceleration and displacement at the pier top and stress at the pier base at a water depth of 10 m, the superposition of temperature effects and hydrodynamic effects results in an increase of 59.06% in acceleration, 25.93% in displacement, and 49.53% in stress than combination effects, respectively. At a water depth of 20 m, the superposition of temperature and hydrodynamic effects results in an increase of 92.82%, 100%, and 127.85% in acceleration, displacement, and stress, respectively. The combined effects of hydrodynamic and temperature effects cannot be described merely as a linear superposition of the two single actions. The research findings provide a significant theoretical basis for understanding the impact of multiple disasters, such as fires and earthquakes, on bridge structures.

Anthropogenic effects on tropical cyclones near Western Europe

There is less consensus on whether human activities have significantly altered tropical cyclone (TC) statistics, given the relatively short duration of reliable observed records. Understanding and projecting TC frequency change is more challenging in certain coastal regions with lower TC activity yet high exposure, such as Western Europe. Here, we show, with large-ensemble simulations, that the observed increase in TC frequency near Western Europe from 1966 to 2020 is likely linked to the anthropogenic aerosol effect. Under a future scenario featuring regionally controlled aerosol emissions and substantially increased greenhouse gas concentrations (Shared Socioeconomic Pathway 5-85), our simulations show a potential decrease in TC frequency near Western Europe by the end of the 21st century. These contrasting trends in historical and future TC frequencies are primarily due to the rise for 1966–2020 and potentially subsequent fall for 2030–2100 in TC genesis frequency in the North Atlantic. The response of large-scale environmental conditions to anthropogenic forcing is found to be crucial in explaining the historical and future changes in TC frequency near Western Europe.