Decrease In Frequency Research Articles

Cohesin-mediated 3D contacts tune enhancer-promoter regulation.

Enhancers are key drivers of gene regulation thought to act via 3D physical interactions with the promoters of their target genes. However, genome-wide depletions of architectural proteins such as cohesin result in only limited changes in gene expression, despite a loss of contact domains and loops. Consequently, the role of cohesin and 3D contacts in enhancer function remains debated. Here, we developed CRISPRi of regulatory elements upon degron operation (CRUDO), a novel approach to measure how changes in contact frequency impact enhancer effects on target genes by perturbing enhancers with CRISPRi and measuring gene expression in the presence or absence of cohesin. We systematically perturbed all 1,039 candidate enhancers near five cohesin-dependent genes and identified 34 enhancer-gene regulatory interactions. Of 26 regulatory interactions with sufficient statistical power to evaluate cohesin dependence, 18 show cohesin-dependent effects. A decrease in enhancer-promoter contact frequency upon removal of cohesin is frequently accompanied by a decrease in the regulatory effect of the enhancer on gene expression, consistent with a contact-based model for enhancer function. However, changes in contact frequency and regulatory effects on gene expression vary as a function of distance, with distal enhancers (e.g., >50Kb) experiencing much larger changes than proximal ones (e.g., <50Kb). Because most enhancers are located close to their target genes, these observations can explain how only a small subset of genes - those with strong distal enhancers - are sensitive to cohesin. Together, our results illuminate how 3D contacts, influenced by both cohesin and genomic distance, tune enhancer effects on gene expression.

The response of soil carbon mineralization losses to changes in rainfall frequency is seasonally dependent in an estuarine saltmarsh

Altered rainfall distribution patterns resulting from climate change have substantial effects on soil carbon (C) cycling in terrestrial ecosystems particularly in water-limited regions. However, how rainfall redistribution affects soil C mineralization (CO2 and CH4 fluxes) in humid regions such as of the coastal saltmarshes remain unclear. We conducted mesocosm experiments in an estuarine saltmarsh in the Yellow River Delta of China, where we simulated three rainfall frequency scenarios (high-frequency, medium-frequency and low-frequency) with the same total rainfall amount in the dry and wet seasons, respectively. Soil CO2 and CH4 fluxes were measured before and after rain frequency treatment during a 40-day period for each season. The decrease in rainfall frequency significantly reduced the mean soil CO2 and CH4 fluxes during the dry season, but had no effect on either flux during the wet season. The seasonal variation in the response of soil C mineralization to rainfall frequency changes could be explained by the changes in antecedent soil water and salinity conditions, soil C substrate, microbial activities and diversity. Thus, the effects of changes in rainfall frequency on soil C mineralization are regulated by season, and should be considered when predicting the future C balance of coastal wetland ecosystems. Furthermore, the shift in precipitation frequency distribution towards increasing heavy rainfall events during the dry season in this region will have a great effect on soil C losses, potentially feeding back into the soil C budget and stability in this estuarine saltmarsh.

Compression and self-compression of frequency modulated spherical photon density waves in anisotropic scattering media

We report on the results of a simulation of the photon density waves with pulse amplitude modulation by a complex frequency modulated signal. The problem is considered for the optical properties typical for sea water with anisotropy factor values varying from 0.75 to 0.93 at source-detector distances up to 120 m. It is shown that multiple scattering in a medium does not prevent effective compression of a signal registered using matched detection. Two competing phenomena affecting the detected pulse duration and depending on the central frequency of the modulation signal are discussed. The effect of faster attenuation of high harmonics in a complexly modulated signal leads to the detected signal duration increase as a consequence of multiple scattering. On the other hand, anomalous dispersion of photon density waves in media with scattering anisotropy leads to the pulse self-compression. The simulation results presented in the paper demonstrate the prevalence of different phenomena depending on the central frequency of the modulation signal resulting in a pulse duration decrease or increase in different frequency ranges covering the band from 107 to 2⋅109 Hz. The effect of the phase function shape on the observed effect is also discussed.

In vitro conjugation of IncB/O-plasmid: Minimum inhibitory concentration of β-lactams increases 16-fold in Salmonella enterica compared with Escherichia coli.

The use of antimicrobials in poultry leaves residues in the litter, favoring the emergence of antimicrobial-resistant pathogens and making it a source of contamination. An in vitro 4 × 4 factorial trial was performed to investigate the influence of four treatments, consisting of antimicrobial sub-concentrations, on the transference of IncB/O-plasmid through conjugation in four groups. Each group was composed of one plasmid donor bacterium (Escherichia coli H2332) and a recipient bacterium (Escherichia coli J62 or Salmonella enterica serovars, Enteritidis, Typhimurium, or Heidelberg). Our results showed a little decrease in the conjugation frequency in almost all treatments between the two bacterial species, which varied according to each strain. The MIC test revealed an increase of up to 4096-fold in resistance to beta-lactams in Salmonella serovars after plasmid acquisition. This finding suggests that some genetic apparatus may be involved in increased antimicrobial resistance in Salmonella serovars after the acquisition of primary resistance determinants.

Decreasing global tropical cyclone frequency in CMIP6 historical simulations.

The impact of anthropogenic global warming on tropical cyclone (TC) frequency remains a challenging issue, partly due to a relatively short period of reliable observational TC records and inconsistencies in climate model simulations. Using TC detection from 20 CMIP6 historical simulations, we show that the majority (75%) of these models show a decrease in global-scale TC frequency from 1850 to 2014. We demonstrated that this result is largely explained by weakened mid-tropospheric upward motion in CMIP6 models over the Pacific and Atlantic main development regions. The reduced upward motion is due to a zonal circulation adjustment and shifts in Intertropical Convergence Zone in response to global warming. In the South Indian Ocean, reduced TC frequency is mainly due to the decreased survival rate of TC seeds because of an increased saturation deficit in a warming climate. Our analysis highlights global warming's potential impact on the historical decrease in global TC frequency.

Original Insights Into Rock Slope Damage Processes Until Collapse From Passive Seismic Monitoring

AbstractWe performed a passive seismic monitoring of the La Praz ∼14,000 m3 unstable slope (French Alps) spanning over 10 years. During the last 6 months prior to collapse, we detected a clear 24% decrease in the slope's fundamental resonance frequency, f0, caused by a reduction in overall rock mass stiffness. The combined study of f0 and slope deformation suggested the alternating importance of sudden brittle failure processes versus more ductile phases with possible sliding. Seismic monitoring revealed slope damage that remained ambiguous or undetected with ground surface deformation monitoring, and highlighted critical periods with intense damage. Only some of these critical damage periods could be related to clear external forcing factors such as intense rainfall episodes. These new insights into rock slope's structural condition at depth represent an asset for future monitoring systems. Surface deformation and passive seismic stiffness tracking combined could reveal active slopes with ongoing damage processes.

Early Changes in Nutritional Status of Elderly Patients with Lung Cancer Undergoing Chemotherapy Are Positively Related with Symptoms of Depression: A Prospective Follow-Up Study

This study aims to assess early effects of chemotherapy on symptom alleviation, nutritional status, and mental health in elderly patients with advanced non-small-cell lung cancer (NSCLC). This prospective study included 45 NSCLC patients (32 males, 13 females) aged 65–82 years (mean age 70.0 ± 4.5 years) with good performance status. Assessments were conducted immediately after diagnosis and after two chemotherapy cycles, focusing on nutritional status (assessed with MNA questionnaire), quality of life (QoL, based on FACT-L and FACT-TOI questionnaires), lung cancer-related symptoms (based on LCSS), and mental health (based on PHQ-9 questionnaire). Despite significant alleviation of symptoms like cough, dyspnea, and body weight loss, there was no significant correlation between changes in symptoms burden and changes in nutritional status (r 2 = 0.122, P = 0.427), and change of patients’ mental condition (r 2 = –0.141, P = 0.255). No significant QoL changes were noted, but a decrease in severe depression frequency was observed. The improvement of patients’ mental condition was related strictly to the improvement of nutritional status (r 2 = -0.589, P < 0.001). The study highlights the vital link between nutritional status and mental health in elderly NSCLC patients, emphasizing the need for integrated care approaches that address both aspects to enhance treatment effectiveness and patient well-being.

ПІДВИЩЕННЯ ЕНЕРГЕТИЧНОЇ ЕФЕКТИВНОСТІ РЕГУЛЬОВАНОГО ЕЛЕКТРОПРИВОДУ ОДНОЦИЛІНДРОВОГО ПОРШНЕВОГО КОМПРЕСОРА

The peculiarities of the operation of closed systems of adjustable electric drives of single-cylinder reciprocating compressors due to the presence of a non-linear dependence between the motor load torque and the angular movement of its rotor are considered. The method of synthesis of the regulator of the amplitude of the supply voltage of an induction motor of such an electric drive at a fixed value of the supply frequency is proposed. According to the results of research, it was found that the effect of increasing energy efficiency (reducing the difference in efficiency for constant and periodic loads) due to the use of a voltage regulator increases with a decrease in the power supply frequency. It is shown that the optimization of the transmission coefficient of the voltage regulator of electric drives with a non-linear dependence between the motor load torque and the angular movement is expedient to be carried out according to the criterion of maximum efficiency. References 25, figures 10, table 1.

Controlled Study of Pre- and Postoperative Headache in Patients with Sellar Masses (HEADs-uP Study).

Sellar masses are common intracranial neoplasms. Their clinical manifestations vary widely and include headache. We aimed to determine whether the prevalence and characteristics of headache in patients with sellar tumours differ from the general population and to investigate the effect of tumour resection on this complaint. We performed a prospective, controlled study in a single tertiary centre and included 57 patients that underwent transsphenoidal resection for a sellar mass (53% females, mean age 53.5 ± 16.4) and 29 of their partners (controls; 45% females, mean age 54.8 ± 14.9). Outcome measures were prevalence, characteristics and impact of headache 1 month preoperatively and at neurosurgical follow-up 3 months postoperatively. Preoperatively, the prevalence of regular headache (≥1 time per month) was higher in patients than in controls (54% vs. 17%, p < 0.001), and patients scored higher on headache impact questionnaires (all p ≤ 0.01). At postoperative follow-up, headache prevalence decreased in both groups, but the decrease in regular headache frequency and impact was larger in patients than in controls, and no between-group differences remained. More than half of patients with sellar tumours suffer from at least once-monthly headaches, and both regular headache occurrence and impact are higher compared with controls. The more pronounced decrease in headache complaints in patients versus controls at postoperative follow-up suggests an additional effect of tumour resection next to the factor time.

Between 2008 and 2022, Lower-Extremity Injuries Declined in Male Rugby Players, Whereas Noncontact Knee Injuries Showed No Decline in Female Rugby Players

PurposeThe purpose of this study was to assess the distribution and mechanisms of lower extremity injuries among high school and college age rugby players presenting to United States (US) emergency departments (EDs) from 2008 to 2022. MethodsThe National Electronic Injury Surveillance System (NEISS) was queried for lower extremity rugby injuries (ages 14-23) from January 2008 to December 2022. Patient demographics, injury location, diagnosis, and disposition were extracted for each case. Linear regression analysis assessed differences over time. Injury distribution for males versus females was evaluated using Pearson’s chi-square analysis. ResultsAn estimated 31,318 (845 NEISS cases) high school and college-age rugby players presented to US EDs with a lower extremity injury during the study period. Males accounted for 66.9% of the injuries. Linear regression analysis revealed a significant decrease in annual frequency of lower extremity injuries presenting to US EDs from 2008 to 2022 (p=0.001). The most common injury mechanism was overwhelmingly a non-contact twisting motion (11,108, 35.5%) followed by a hit/collision (5,298, 16.9%). Strains/sprains were the most common diagnosis (17,243, 55.1%). Injuries most commonly occurred at the ankle (12,659, 40.4%) and knee (11,016, 35.2%). In a sex-specific linear regression analysis, there was a significant decrease in lower extremity injuries sustained by male players (p=0.001), but no significant decrease among female players (p=0.112). Furthermore, chi-squared analysis revealed that females sustained a significantly higher proportion of knee injuries secondary to twists (15.9% for females vs. 9.0% for males, p=0.01). ConclusionLower extremity injuries are declining among high school and college-age male rugby players. However, there has not been a corresponding decrease among female rugby players. Furthermore, females are disproportionately affected by non-contact twisting knee injuries.

An Analysis of the Cognitive Demands of Senior High School English as a Foreign Language Textbooks in China

This study aims to reveal the cognitive demands of senior high school English as a foreign language textbooks in China and their potential impact on students’ thinking development. To achieve this, the study employed content analysis, using an analytical framework adapted from the revised Bloom’s taxonomy, to examine the cognitive demands incorporated in the activities across nine target textbooks from three different publishers. The study found “Understand” to be the most common cognitive demand in the examined textbooks. However, it also identified that lower cognitive demands “Remember,” “Understand,” and “Apply” were less prevalent than the higher demands “Analyze,” “Evaluate,” and “Create.” Additionally, the study observed variations in the distribution of cognitive demands within the textbooks for 10th, 11th, and 12th grades. Despite these variations, the distribution of cognitive demands across the three grade-level textbooks was found to be remarkably similar, with an increase in the occurrence frequency of cognitive demands “Apply,” “Analyze,” “Evaluate,” and “Create,” and a corresponding decrease in the occurrence frequency of cognitive demands “Understand” and “Remember.” These findings indicate that senior high school English as a foreign language textbooks in China are intentionally designed to accommodate the thinking skill needs of students at each grade level and to promote the development of their thinking skills, with a particular emphasis on higher-order thinking skills. The findings hold significant implications for the design and use of language textbooks, highlighting the importance of integrating appropriate and challenging cognitive demands to effectively support students’ thinking development.

Closing Eyes with Artificial Tears: A Simple and Effective Strategy to Combat Screen-Related Asthenopia and Dry Eye Symptoms

BackgroundThe widespread use of various video display terminals (VDTs) always had a detrimental impact on ocular health. Prolonged use of smartphones has been one of the leading causes of dry eye (DE) and asthenopia. Therefore, the purpose of this study is to find a simple and effective strategy to combat screen-related DE and asthenopia. MethodsA group of healthy participants aged 18 and above were randomly assigned to three groups and tasked with a 2-hour smartphone reading task. After 1 hour of usage, each group adopted different methods of rest: no rest (Group A), a 10-minute eye-closed rest (Group B), or a 10-minute eye-closed joint artificial tears rest (Group C). Ophthalmological examinations and questionnaires were administered to all participants before and after the 2-hour reading task. Results90 qualified volunteers, including 29 males and 61 females, were randomly assigned to three groups. Group A demonstrated a significant increase in the severity of DE and asthenopia as evidenced by all the evaluated indices. On the other hand, Group C did not exhibit any notable change in DE and asthenopia symptoms, with an improvement in corneal fluorescein staining (CFS) results (p > 0.05) when compared to the pre-reading values. Group B showed a significant increase in ocular surface disease index (OSDI) (p ≤ 0.05) and a decrease in critical flicker frequency (CFF) (p ≤ 0.05). ConclusionsClose-eye rest with artificial tears may be a convenient and effective prevention strategy for screen-related DE and asthenopia.

Dzikr Relaxation to Decrease College Student's Anxiety and Increase Happiness

This study aimed to determine the effectiveness of dhikr relaxation in reducing anxiety and increasing happiness in college students. The subjects were 16 students of UIN Sunan Kalijaga aged 19-23 years. There were 2 hypotheses in this research. This research method was conducted by using quasi-experimental with a pretest and posttest control group design. Data collection tools were the HARS scale (Hamilton Anxiety Rating Scale), the OHQ scale (The Oxford Happiness Questionnaire), and Nexus Biofeedback. The data analysis used the Mann-Whitney U Test. The results of the first study showed that there was a difference in the anxiety score between the control group and the experimental group that took part in dhikr relaxation therapy, where the experimental group's score was greater than the control group's score as evidenced by the sig. of 0.005 (p&lt;0.05). The results of the second study showed that there was no difference in the happiness score between the control group and the experimental group that took part in dhikr relaxation therapy, where the experimental group's score was greater than the control group's score as evidenced by the sig value. of 0.161 (p&gt;0.05). The results of the analysis using the Nexus Biofeedback tool showed the sig. 0.028 (p&lt;0.05). It can be concluded that dhikr relaxation was effective in reducing anxiety as indicated by a decrease in respiration frequency using the Nexus Biofeedback tool. However, dhikr relaxation has not been effective in increasing students’ happiness.

Clinical, functional and aberrometric parallels in the treatment of the neovascular form of age-related macular degeneration

Purpose: to analyze clinico-functional and aberrometric parameters of patients with the neovascular form of age–related macular degeneration (nAMD) treated by the anti-VEGF drug brolucizumab. Material and methods. The study involved 59 patients (59 eyes) aged 55 to 75 years, divided into two groups depending on the type of treatment. Group 1 consisted of 25 patients (25 eyes) who had previously received no anti-VEGF therapy and Group 2 had 34 patients (34 eyes) with an active nAMD form, who had previously been given anti-angiogenic therapy with aflibercept. All patients averagely received 5.48±1.5 brolucizumab injections in the “treat and extend” mode: 3 loading injections with monthly checkups followed by elongated intervals reaching 8 weeks. The treatment effectiveness was estimated by the change in maximum corrected visual acuity (MCVA) as measured by precision visometry, the aberrations parameters of the optical system of the eye, and the thickness of the central retinal zone (CRZ). In addition, the height of retinal pigment epithelium (RPE) detachment, the presence of intraretinal fluid (IRF), subretinal fluid (SRF), and fluid under RPE. Results. In group 1, BCVA whose initial value was 0.37 ± 0.16 reached 0.78 ± 0.25 (p = 0.02) by the end of treatment, while in group 2, the value rose from 0.35 ± 0.18 to 0.62 ± 0.22 (p = 0.02). After the 5th injection, Group 1 showed a statistically significant decrease in TCZV (ave. by 270.17 ± 92.37 μm, p=0.05), while Group 2 showed a less pronounced morphological result (a decrease from 480.54 ± 174.22 to 320.32 ± 109.53, p &lt; 0.05). Both groups also showed, after the 5th injection, a decrease in the cumulative frequency of occurrence of various types of fluid (p &lt; 0.02). A decrease in all components of higher order aberrations was also noted after the first 3 injections; this result remained stable until the end of the observation period (p = 0.04). Conclusion. In Group 1 patients, we succeeded in achieving high morphological and functional results and maintaining them at a stable level until the end of the observation period. Group 2, patients with an active nAMD, previously treated with other anti-VEGF preparations, showed a less pronounced, though stable improvement in morphofunctional parameters.

Thermomechanical Response of Smart Magneto-Electro-Elastic FGM Nanosensor Beams with Intended Porosity

AbstractThis study investigates the behavior of free vibrations in a variety of porous functionally graded nanobeams composed of ferroelectric barium-titanate (BaTiO3) and magnetostrictive cobalt-ferrite (CoFe2O4). There are four different models of porous nanobeams: the uniform porosity model (UPM), the symmetric porosity model (SPM), the porosity concentrated in the bottom region model (BPM), and the porosity concentrated in the top region model (TPM). The nanobeam constitutive equation calculates strains based on various factors, including classical mechanical stress, thermal expansion, magnetostrictive and electroelastic properties, and nonlocal elasticity. The study investigated the effects of various factors on the free vibration of nanobeams, including thermal stress, thermo-magneto-electroelastic coupling, electric and magnetic field potential, nonlocal features, porosity models, and changes in porosity volume. The temperature-dependent mechanical properties of BaTiO3 and CoFe2O4 have been recently explored in the literature for the first time. The dynamics of nanosensor beams are greatly influenced by temperature-dependent characteristics. As the ratios of CoFe2O4 and BaTiO3 in the nanobeam decrease, the dimensionless frequencies decrease and increase, respectively, based on the material grading index. The dimensionless frequencies were influenced by the nonlocal parameter, external electric potential, and temperature, causing them to rise. On the other hand, the slenderness ratio and external magnetic potential caused the frequencies to drop. The porosity volume ratio has different effects on frequencies depending on the porosity model.

Characterization of Fiber Bragg Grating Accelerometer for Underwater Vibration Detection

In this paper, the results of the characterization of a Fiber Bragg Grating (FBG) Accelerometer for detecting vibrations underwater are reported. The FBG Accelerometer, consisting of three FBGs, is utilized to detect underwater vibrations in three-dimensional directions. A water pump, with positions varied from 0 to 10 cm, is employed as the vibration source. Furthermore, the experimental results are presented in the form of the peak wavelength shift reflected by the FBG (ΔλB) and frequency. From the experiment results, it is shown that with increasing distance, ΔλB decreases linearly with successive gradients of 0.0058 nm/cm; 0.0059 nm/cm; and 0.0045 nm/cm. for FBG X, Y, and Z. It is also shown that with increasing distance, there is a decrease in frequency from 50 Hz for FBGs X, Y, and Z to 39 Hz; 38 Hz; and 40 Hz for FBGs X, Y, and Z respectively.

Study on properties of reinforced concrete structures in seismic regions

This paper aims to explore the effects of earthquakes on the properties of medium-height reinforced concrete houses in China. The results demonstrated a significant decrease in ultrasonic resonance frequency, indicating structural damage, with reductions of 26.5 %, 30.2 %, and 37 % observed for earthquakes of magnitudes 5.0, 5.3, and 5.7, respectively. Similarly, the dynamic modulus of elasticity exhibited a reduction of over 50 %. Measurements of carbonation depth revealed values of 34.65 mm, 38.97 mm, and 46.12 mm for earthquakes of magnitudes 5.0, 5.3, and 5.7, respectively. Accordingly, the percentage of mass loss amounted to 22.17 %, 36.87 %, and 49.78 %. Furthermore, experiments identified the least favourable outcomes during maximum seismic activity, with a recorded peak stress of 447.3 MPa at a deformation of 0.63 mm. These findings contribute to a better understanding of the impact of seismic events on reinforced concrete structures and the associated corrosion mechanisms.

Temporal variations of the ‘in-situ’ nonlinear behaviour of shallow sediments during the 2016 Kumamoto Earthquake sequence

SUMMARY Strong ground shaking has the potential to generate significant dynamic strains in shallow materials such as soils and sediments, thereby inducing nonlinear site response resulting in changes in near-surface materials. The nonlinear behaviour of these materials can be characterized by an increase in wave attenuation and a decrease in the resonant frequency of the soil; these effects are attributed to increased material damping and decreased seismic wave propagation velocity, respectively. This study investigates the ‘in-situ’ seismic velocity changes and the predominant ground motion frequency evolution during the 2016 Kumamoto earthquake sequence. This sequence includes two foreshocks (Mw 6 and Mw 6.2) followed by a mainshock (Mw 7.2) that occurred 24 hr after the last foreshock. We present the results of the seismic velocity evolution during these earthquakes for seismological records collected by the KiK-net (32 stations) and K-NET (88 stations) networks between 2002 and 2020. We analyse the impulse response and autocorrelation functions to investigate the nonlinear response in near-surface materials. By comparing the results of the impulse response and autocorrelation functions, we observe that a nonlinear response occurs in near-surface materials. We then quantify the velocity reductions that occur before, during, and after the mainshock using both approaches. This allows us to estimate the ‘in-situ’ shear modulus reduction for different site classes based on V$_{S30}$ values (V$_{S30}\lt 360$ m s−1, $360\lt $V$_{S30}\lt 760$ m s−1 and V$_{S30}\gt 760$ m s−1). We also establish the relationships between velocity changes, shear modulus reduction, variations in predominant ground motion frequencies and site characteristics (V$_{S30}$). The results of this analysis can be applied to site-specific ground motion modelling, site response analysis and the incorporation of nonlinear site terms into ground motion models.

Shaking table tests and numerical analysis of monopile-supported offshore wind turbines under combined wind, wave and seismic loads

Currently, large-diameter monopile-supported offshore wind turbines (OWTs) are widely used in offshore areas of China. However, considerable numbers of wind farms are located in seismically active areas with liquefiable soil layers. Therefore, shaking table tests and numerical simulation based on a scaled model of Siemens SWT-4.0-130 OWTs were carried out to investigate the failure mechanism of the OWT system in liquefiable sand under combined wind, wave and seismic loads. The scaling law focusing on the governing physical mechanism of the OWT system considering multi-field coupling are presented and verified. The dynamic responses of the OWT and the excess pore pressure fluctuation around the soil-monopile domain in different operating states are discussed and compared. The results show that the proposed scaling laws can well restore the dynamic characteristics of the prototype. The seismic excitation is the dominant load for inducing the structural response under combined wind, wave and seismic loads. Due to the coupling effect, the dynamic responses under combined wind and wave loads were slightly less than the superposition of structural responses under separated wind or wave loads. Liquefaction of the shallow soil layer within the range of four times the pile diameter was detected when the PGA reached 0.4 g (three-dimensional input) or 0.64 g (one-dimensional input), which induced obvious tilt and settlement of the OWT model after the test. The sudden increase in the pore pressure resulted in the liquefaction of soil, which further led to a significant decrease in the natural frequencies and decay of the acceleration responses at the tower top. The above findings are expected to provide valuable experience for the 1 g underwater shaking table tests on OWT systems and insights for the practical design of OWTs in seismically active areas.

EFG meshless-ANN approach for free vibration analysis of functionally graded material plates on elastic foundation in thermal environments

This study focuses on free vibration analysis of functionally graded material (FGM) plates supported by Winkler–Pasternak elastic foundation in thermal environment using element-free Galerkin (EFG) meshless method. Plate kinematics depend on first-order shear deformation theory. Uniform, linear, and nonlinear temperature variations through the thickness direction are considered, along with the temperature-dependent material properties. The numerical outcomes obtained from EFG method are compared with those available in the published literature to validate the proposed method’s accuracy. An artificial neural network (ANN) model that can easily predict the natural frequencies of the plate is constructed from the EFG method outcomes. Further, the effect of foundation parameters, power law index, thickness ratio, temperature variations, and different boundary conditions are investigated; results show that these significantly influence the vibration response of FGM plates supported by the elastic foundation. Increasing the temperature of FGM plates supported by the Winkler–Pasternack foundation causes a decrease in the dimensionless fundamental natural frequency, and the uniform temperature influence is greater than that of linear and nonlinear temperature variation. The proposed EFG-ANN prediction model saves approximately 98.80% computation time when predicting the natural frequency with an accuracy of approximately 98.76% compared to that by EFG meshless method alone.