Pressure Variation Research Articles

Quantitative assessment of traumatic brain injury risk in diverse age groups of females: Insights from computational biomechanics

Traumatic Brain Injury (TBI) stands as a multifaceted health concern, exhibiting varying influences across human population. This study delves into the biomechanical complexities of TBI within gender-specific contexts, focusing on females. Our primary objective is to investigate distinctive injury mechanisms and risks associated with females, emphasizing the imperative for tailored investigations within this cohort.By employing Fluid-Structure Interaction (FSI) Analysis, we conducted simulations to quantify biomechanical responses to traumatic forces across diverse age groups of females. The study utilized a scaling technique to create finite element models (FEMs). The young female FEM, based on anthropometric data, showcased a 15 % smaller head geometry compared to the young male FEM. Moreover, while the elderly female FEM closely mirrored the young female FEM in most structural aspects, it showed distinctive features such as brain atrophy and increased cerebrospinal fluid (CSF) layer thickness. Notably, the child female FEM (ages 7–11 years) replicated around 95 % of the young female FEM's geometry. These structural distinctions meticulously captured age-specific variations across our modeled female age groups. It's noteworthy that identical conditions, encompassing impact intensity, loading type, and boundary conditions, were maintained across all FEMs in this biomechanical finite element analysis, ensuring comparative results.The findings unveiled significant variations in frontal and occipital pressures among diverse age groups, highlighting potential age-related discrepancies in TBI susceptibility among females. These variations were primarily linked to differences in anatomical features, including brain volume, CSF thickness, and brain condition, as the same material properties were used in the FEMs. These results were approximately 4.70, 6.33 and 6.43 % in frontal area of brain in diverse age groups of females (young, elderly, and child) respectively compared to young male FEM. Comparing the FEM results between the young female and the elderly female, we observed a decrease in occipital brain pressure at the same point, reducing from 171,993 to 167,793 Pa, marking an approximate 2.5 % decrease. While typically the elderly exhibit greater brain vulnerability compared to the young, our findings showcase a reduction in brain pressure. Notably, upon assessing the relative movement between the brain and the skull at the point located in occipital area, we observed greater relative movement in the elderly (1.8 mm) compared to the young female (1.04 mm). Therefore, brain atrophy increases the range of motion of the brain within the cranial space. The study underscores the critical necessity for nuanced TBI risk assessment tailored to age and gender, emphasizing the importance of age-specific protective strategies in managing TBIs across diverse demographics. Future research employing individual modeling techniques and exploring a wider age spectrum holds promise in refining our understanding of TBI mechanisms and adopting targeted approaches to mitigate TBI in diverse groups.

Magnitude of and Hydroclimatic Controls on CO2 and CH4 Emissions in the Subtropical Monsoon Pearl River Basin

AbstractRivers are important ecosystems for carbon emissions and play a crucial role in the global carbon cycle. However, CO2 and CH4 emissions from subtropical rivers are substantially under‐represented in global‐scale estimates. Here, we explored the regional patterns of riverine CO2 and CH4 dynamics in the Pearl River basin with a subtropical monsoon climate. We found that its CO2 and diffusive CH4 emissions showed a decreasing trend with increasing stream order. Seasonality in CO2 and diffusive CH4 emissions was primarily driven by variations in partial pressure of CO2 (pCO2) and CH4 (pCH4) and gas transfer velocities, which were strongly regulated by hydrology and climate. We further estimated the basin‐wide CO2 and diffusive CH4 fluxes at 17.8 ± 7.4 Tg C yr−1 and 191.5 ± 139.9 Gg C yr−1, respectively. When normalized to the water surface, the mean diffusive fluxes were 790.1 and 8.5 mmol m−2 d−1 for CO2 and CH4, respectively, which were 1.3 and 2.5 times higher than the global mean riverine CO2 and CH4 fluxes, respectively. This suggests that the global significance of subtropical rivers is probably underestimated because their substantially higher CH4 fluxes are unaccounted for. Furthermore, compared with measured pCO2, the alkalinity‐based pCO2 could introduce significant errors by 20% at ∼30% of the sampling sites, underscoring the necessity of direct measurements to reduce uncertainty. This study provides the first estimate of basin‐wide CO2 and diffusive CH4 emissions in the PRB through direct pCO2 and pCH4 measurements, and highlights the role of hydrologic and climatic factors in governing riverine carbon emissions.

Does spatial variation in insect herbivory match variations in plant quality? A meta-analysis.

Variation in herbivore pressure has often been predicted from patterns in plant traits considered as antiherbivore defences. Here, we tested whether spatial variation in field insect herbivory is associated with the variation in plant quality by conducting a meta-analysis of 223 correlation coefficients between herbivory levels and the expression of selected plant traits. We found no overall correlation between herbivory and either concentrations of plant secondary metabolites or values of physical leaf traits. This result was due to both the large number of low correlations and the opposing directions of high correlations in individual studies. Field herbivory demonstrated a significant association only with nitrogen: herbivore pressure increased with an increase in nitrogen concentration in plant tissues. Thus, our meta-analysis does not support either theoretical prediction, i.e., that plants possess high antiherbivore defences in localities with high herbivore pressure or that herbivory is low in localities where plant defences are high. We conclude that information about putative plant defences is insufficient to predict plant losses to insects in field conditions and that the only bottom-up factor shaping spatial variation in insect herbivory is plant nutritive value. Our findings stress the need to improve a theory linking plant putative defences and herbivory.

Intervention of hypertension by acupuncture-related therapies: A network meta-analysis.

The prevalence of essential hypertension contributed significantly to morbidity and mortality rates. Acupuncture-related therapies were commonly employed in hypertension treatment. Nevertheless, a lack of conclusive evidence left uncertainties regarding the optimal strategies for managing hypertensive populations. Conduct a comprehensive systematic review to evaluate the existing clinical evidence about the effectiveness of acupuncture and moxibustion-related therapies in managing hypertension, by employing network meta-analysis techniques. A comprehensive electronic search was conducted across n of databases. This search covered studies available up to October 2022. Randomized controlled trials assessing acupuncture and moxibustion-related therapies in managing hypertension based on traditional Chinese medicine were screened. Primary outcome measures included the antihypertensive effectiveness rate, variations in blood pressure and the incorporation of Traditional Chinese Medicine (TCM) syndrome manifestations. The review follows the guidelines outlined in the PRISMA statement. We identified a total of 24 trials with 1867 patients, which evaluated the efficacy of various acupuncture-related therapies for hypertension management. Network meta-analysis showed that moxibustion and auricular point sticking combined with medication therapy had the best effect in terms of antihypertensive effective rate (medication + moxibustion + auricular pressure vs. medication = 1.29 [1.09, 1.54]; sucra = 85.9, p < .05) and hypertension symptom improvement (medication + moxibustion + auricular pressure vs. medication = -1.55 [-2.98, -0.13]; sucra = 96.1, p < .05). Acupuncture combined with moxibustion combined with medication therapy had the best effect in reducing systolic pressure (medication + moxibustion + acupuncture vs. medication = -8.50 [-10.19, -6.80]; sucra = 100, p < .05) and diastolic blood pressure (medication + moxibustion + acupuncture versus medication = -4.72 [-6.71, -2.72]; sucra = 99.71, p < 0.05). Network meta-analysis suggested that the combined use of moxibustion and auricular point application in conjunction with drug therapy showed the highest likelihood of being the most effective treatment in terms of antihypertensive efficiency rates and improvement in hypertension symptoms. Furthermore, the combination of acupuncture and moxibustion alongside drug treatment emerged as the most promising approach for reducing systolic blood pressure and diastolic blood pressure. Limited by the methodological quality and quantity of the included studies, the results need to be interpreted with caution. It is necessary to conduct more high-quality randomized controlled trials of acupuncture-related therapies for the adjuvant treatment of hypertension in the future. Clinicians can use acupuncture-related therapies to inform their treatment decisions and potentially incorporate acupuncture-related therapies into their hypertension management protocols.

AN EXPLANATION FOR UNDERESTIMATION OF SYSTOLIC PRESSURE IN CUFF-BASED MEASUREMENT

Objective: Auscultatory blood pressure measurement is the gold standard used to calibrate other measurement devices. However, auscultatory tests systematically underestimate systolic blood pressure (SBP) and overestimate diastolic blood pressure (DBP). While there is some literature explaining overestimation, there is no physical understanding of the underestimated SBP. Our objective is to understand why auscultatory measurement results in the underestimation of SBP. The SBP is recorded when the artery first begins to reopen, during cuff deflation. Prior to this, the cuff cuts off the blood supply and the pressure in the distal part of the artery drops to the venous pressure. We propose this low pressure as a cause of underestimation and investigate this through a controlled variation of the downstream pressure in an experimental rig. Design and method: Figure 1 shows a schematic of the rig. The tube representing the artery is compressed under an inflatable cuff. The downstream pressure is varied between tests. The upstream pressure is fixed with a header tank for simplicity. Therefore, the ‘blood pressure’ measured in the rig is constant rather than oscillatory, resulting in only a single opening of the artery as the cuff is deflated, rather than repeated opening and closing. This single opening is equivalent to the first opening of the artery in the body and so represents the systolic measurement. Figure 2 depicts an example test run. The cuff around the artery is gradually deflated, and the reopening of the artery is indicated by the rise of the downstream pressure (point a). The cuff pressure at this timestamp is recorded (point b), representing the measured SBP. Results: Figure 3 shows that the recorded cuff pressure is a function of downstream pressure, with the cuff reading giving greater underestimation of SBP when the downstream pressure is lowered. Conclusions: The delay in artery reopening which results from lowering the downstream pressure provides an explanation for the systematic underestimation of SBP. This information may lead to recommendations for new measurement protocol which avoid a drop in the pressure distal to the cuff, and the resulting underestimation of SBP.

The structure of cross-ventilation flow in an isolated cylindrical building: Numerical study

Cross-ventilation serves as an efficient means to expel pollutants and heat from buildings, requiring no energy consumption due to variations in wind pressure. The structure of the cross-ventilation flow significantly influences ventilation effectiveness. However, limited attention has been given to understanding the impact of a building's cross-section on the structure of cross-ventilation flow. This study aims to fill this gap by numerically investigating the cross-ventilation flow structure in an isolated cylindrical building. The numerical simulation results are validated against reported experimental data, indicating a negligible simulation error of 0.8 % in the volume ventilation rate. This attests to the accuracy of the numerical method in predicting cross-ventilation flow in isolated buildings. As airflow traverses the cylindrical building along the curved side walls, pressure loss diminishes, facilitating increased air inflow. This results in a more horizontal entry of the incoming jet compared to that in a square building. Analysis of Root-Mean-Square streamwise-velocity and turbulence kinetic energy reveals greater airflow fluctuation outdoors for the square building and increased turbulence indoors for the cylindrical building. Notably, the volume ventilation rate of the cylindrical building demonstrates an 8.3 % improvement. Furthermore, the air exchange rate in the cylindrical building surpasses that of the square building by 1.38 times.

Constitutive modeling of anisotropic small-strain stiffness behavior of Shanghai soft clay

Small strain stiffness plays an important role in determining the deformation of geotechnical engineering in soft soils. To model the anisotropic small strain stiffness behavior of soft clay, an enhancement to the bounding surface plasticity model is proposed. This enhancement involves incorporating the anisotropy in soil stiffness at very small strains and its non-linear degradation. Small strains are considered via cross-anisotropy elasticity, while the concept of intergranular strain is used to reflect the non-linear degradation of stiffness with strains and the effect of recent stress history. Using the proposed model, the triaxial test results on K0 consolidated Shanghai clay specimens are simulated to investigate the model’s performance. In the simulation, three typical shear stress paths are adopted. The comparison of the model simulations against experimental evidence is discussed, where the effects of anisotropy in initial soil stiffness and stress-induced anisotropy on the variation of small-strain stiffness, pore pressure, and shear-volume coupling response are highlighted.

Experimental investigation on effects of temperature and launch pressure on variations of the impact acceleration in cross media water-entry process

In the paper, effects of temperature and launch pressure on variations of the maximum impact acceleration in cross media water-entry process are systematically investigated via experiments. Results indicated that under the water entry angle of 25°, the maximum impact acceleration increased gradually with the growing of launch pressure from 2.5MPa to 3.0MPa when the temperature is 30°C, 40°C, and 50°C. The maximum impact acceleration decreased constantly with the increase of the temperature from 30°C to 50°C when launch pressure is the constant. According to the comprehensive analysis, effect degrees of variations of the launch pressure on the maximum impact acceleration are more significant than that of the variations of temperature.

Insights into a New Multi‐Stimuli‐Responsive Photochromic Metal‐Organic Framework: Highly Sensitive Turn‐On Luminescence in a Lanthanum Phosphonate

AbstractThe new microporous metal organic framework [La2(H2O)5(H2TPPE)]·3H2O (CAU‐54), is obtained in a hydrothermal reaction of the linker 1,1,2,2‐tetrakis(4′‐phosphonophenyl)ethylene (H8TPPE) and La3+ ions. The extensive characterization including temperature‐dependent crystal structures and spectroscopic properties allowed to understand the unique, multi‐responsive material properties. CAU‐54 exhibits rarely observed reversible photochromism as well as turn‐on photoluminescence by various external chemical or physical stimuli including change of pressure, solvent exchange, and temperature variation. These properties can be unequivocally assigned to the presence of tetraphenylethylene (TPE) moieties of the linker molecules within the MOF, i.e., the ordered spatial arrangement of the linker molecules, the presence of accessible pores as well as the coordination flexibility of the phosphonate groups and the rotational freedom of the linker. By temperature‐dependent steady‐state and time‐resolved luminescence studies, it is shown that this compound exhibits a) blue fluorescence that becomes effectively quenched at room temperature, b) green efficient luminescence with thermal stability up to 400 K, and c) red phosphorescence correlated to the observed photochromism. In addition, CAU‐54 shows unusual thermal expansion properties as shown by temperature‐dependent powder X‐ray diffraction measurements with identified transition points that correlate with the observed temperature‐dependent changes in the photoluminescence.

Diagnostic accuracy of Plethysmographic Variability Index for the prediction of high pulse pressure variation in neurosurgery using a gray-zone approach: a retrospective study

Diagnostic accuracy of Plethysmographic Variability Index for the prediction of high pulse pressure variation in neurosurgery using a gray-zone approach: a retrospective study

Quantitative validation of the suprasternal pressure signal to assess respiratory effort during sleep

Objective. Intra-esophageal pressure (Pes) measurement is the recommended gold standard to quantify respiratory effort during sleep, but used to limited extent in clinical practice due to multiple practical drawbacks. Respiratory inductance plethysmography belts (RIP) in conjunction with oronasal airflow are the accepted substitute in polysomnographic systems (PSG) thanks to a better usability, although they are partial views on tidal volume and flow rather than true respiratory effort and are often used without calibration. In their place, the pressure variations measured non-invasively at the suprasternal notch (SSP) may provide a better measure of effort. However, this type of sensor has been validated only for respiratory events in the context of obstructive sleep apnea syndrome (OSA). We aim to provide an extensive verification of the suprasternal pressure signal against RIP belts and Pes, covering both normal breathing and respiratory events. Approach. We simultaneously acquired suprasternal (207) and esophageal pressure (20) signals along with RIP belts during a clinical PSG of 207 participants. In each signal, we detected breaths with a custom algorithm, and evaluated the SSP in terms of detection quality, breathing rate estimation, and similarity of breathing patterns against RIP and Pes. Additionally, we examined how the SSP signal may diverge from RIP and Pes in presence of respiratory events scored by a sleep technician. Main results. The SSP signal proved to be a reliable substitute for both esophageal pressure (Pes) and respiratory inductance plethysmography (RIP) in terms of breath detection, with sensitivity and positive predictive value exceeding 75%, and low error in breathing rate estimation. The SSP was also consistent with Pes (correlation of 0.72, similarity 80.8%) in patterns of increasing pressure amplitude that are common in OSA. Significance. This work provides a quantitative analysis of suprasternal pressure sensors for respiratory effort measurements.

Experimental investigation of tail void grouting pressure evolution for super-large diameter shield tunnels

The shield tunneling method is widely used in underground construction. Factors such as the variations in grouting pressure and stiffness/strength evolution over space and time directly affect ground deformation and system stability. To investigate the effect of grouting pressure variation, grouting influence zone, and hydromechanical properties on the model responses (e.g., surface settlement and lining forces), an innovative model test setup was developed to simulate the tunneling process wherein the lining could settle or float during grout injection. This setup included tunnel shrinking, loading-unloading, grout injection, and sample preparation systems. The experimental results show that the grouting pressure evolution law may be significantly affected by the tunnel translation. When the tunnel centerline was fixed in the traditional model tests, the resulting grouting pressure in the tail void was lower than that when the tunnel was free to move. This is because the tunnel translation changed the shape of the annular gap and contributed to the measured grouting pressure. The proposed setup is capable of revealing a more realistic law of grouting pressure evolution, and the subsequent spatio-temporal grouting-induced soil/lining behavior is currently being investigated.

Dynamic analysis of bird strike effect on the polymeric composite fuselage nose

A collision with a bird while in flight poses a substantial hazard to the structural integrity of aircraft. Due to these collisions, the damage occurs in the aircraft mostly in the engines, windshields, nose part, wing leading edges and other components. Reduction of bird impact is possible by carrying out suitable design and analysis using mathematical modelling and simulations. Hence, the focus of this numerical study is to analyze the high velocity impact loads from soft body projectiles on the composite structures using dynamic analysis. The analysis is carried out using LS-DYNA software. The nose part is considered as deformed target while the bird is assumed fluid during impact. The temporal pressure variations is measured on the curved plate using dynamic analysis for different bird velocities namely, 50 m/s, 100 m/s, 150 m/s, 200 m/s and 250 m/s with a nose cone thickness of 3 mm. Lagrangian method is used for finding temporal pressure variation. An increase in impact velocity of the impactor increases the impact pressure of the fuselage nose cone with respect to time.

Study of Chemical Composition and Evaluation of Anti-hypertensive Effect of A Fixed Oil Extracted from Linum usitatissimum grains

Globally grown flax seed is regarded as an oilseed with numerous medicinal and health are the outcomes of the physico-chemical analyses: pH value: 0.476; saponification index: 168.3; KOH/g: 28.05; peroxide index: 174; density: 0.951; refractive index: 1.482 at 18.1°C and 1.485 at 18.2°C; peroxide index: 1.70 at 0.96, 1.70 mg/100; all are related to the peroxide index. In this study we tried to test the ” anti-hypertension “ activity of this oil by simulating a blood cycle in the laboratory which allowed us to determine the variation in blood pressure as a function of the volume of oil injected into the blood cycle from 17.4 to 14.10. benefits such as: lowering blood pressure, blood sugar, decreasing the risk of neurological and obesity-related illnesses. The objective of this study is to extract the linseed oil and to characterize it chemically and physically; by pressing the seeds into two different temperatures : 67°C and 90°Coil yields ; 24% and 29% were obtained from linseed. The followings

Analysis of Anaerobic Digestion Installation Testing for Tofu Liquid Waste Utilization into Biogas with the Addition of Cow Manure Variations

The purpose of this study is to convert tofu wastewater into biogas using an anaerobic digester with varying cow dung mixtures (10%, 15%, and 20%). The study method entails creating digesters including independent, dependent, and controlled variables. Variations in pH, temperature, biogas pressure, and biogas volume were detected throughout the course of a 15-day fermentation. The data show that in the 10% fluctuation, the greatest pH was on day 7 (7), whereas the highest temperature was 32°C on days 6 and 7. Biogas pressure emerged on day 6 (89.2 cmHg), resulting in a volume of 90 liters by day 15. In the 15% variation, the highest pH (7.2) occurred on day 8, with the highest temperature (34°C) on days 9 and 10. Biogas pressure began on day 5 (89.9 cmHg), with a biogas volume of 95 liters on day 15. The 20% variance resulted in the highest pH (7.4) on day 8 and the highest temperature of 35°C from days 9-11. Biogas pressure began on day 5 (90.7 cmHg), resulting in a biogas volume of 100 liters on day 15. This study sheds light on how to manage tofu waste into biogas with varying degrees of effectiveness and efficiency.

Interface evolution of lithium metal anodes in all-solid-state batteries via mechanical–electrochemical investigations

All-solid-state Li metal batteries (ASSLMBs) have garnered attention owing to the high-energy density and low redox potential of Li metal anodes. However, the practical applications of ASSLMBs are hindered by issues such as the volume effect of Li anodes and Li dendrite growth. In this study, a combined method of stacking pressure analysis, interface morphology observation, and electrochemical impedance spectroscopy was used to investigate the electrochemical failure of Li symmetric batteries based on the Li6PS5Cl electrolyte at areal capacities of 0.5, 1, and 3 mAh cm−2. The results indicated that ASSLMBs with areal capacities >1 mAh cm−2 exhibited a continuous decrease in the stacking pressure. As Li dendrites/dead Li and pores/cracks increased, stacking pressure variations of >0.1 MPa per cycle and a stacking pressure change rate > 0.2 MPa h−1 were observed, indicating impending battery failure owing to interface detachment. These findings provide new insights into the interface evolution of Li anodes of ASSLMBs and emphasize the importance of electrochemical–mechanical measurements in studying Li anode interfaces of ASSLMBs.

Numerical Investigations on the Jet Dynamics during Cavitation Bubble Collapsing between Dual Particles

The jet dynamics during cavitation bubble collapsing between unequal-sized dual particles are investigated utilizing a numerical model that combines the finite volume approach alongside the volume of fluid approach. The model incorporates the compressibility of the two-phase fluid and accounts for mass and heat transfer between two phases. The computational model utilizes an axisymmetric model, where the axis of symmetry is defined as the line that connects the centers of the particles and the bubble. A comprehensive analysis is presented on the influence of the particle radius and bubble–particle distance on the jet behavior. Furthermore, the variations of surface pressure on the particles induced by jet impingement are quantitatively analyzed. Four distinct jet behaviors are categorized, depending on the formation mechanism, as well as the number and the direction of the jets. For case 1, the bubble produces a single jet directed toward a small particle; for case 2, the bubble fragments produces double jets receding from each other; for case 3, the bubble produces double jets approaching each other; and for case 4, the bubble produces a single jet directed toward a large particle. The pressure perturbations induced by jet impingement upon the particles exceed those caused by shock wave impacts. The larger the bubble volume at the moment of jet formation, the longer the duration of the pressure variation caused by the jet impinging on the particles.

Modified calculation model of train-induced aerodynamic pressure on vertical noise barriers considering the train geometry effect

High-speed trains (HSTs) generate air disturbance, leading to significant aerodynamic pressure on the noise barriers. Differences in train geometry result in variations in the aerodynamic pressure on noise barriers, implying that existing European standard calculation models may not necessarily be suitable for all types of HSTs. In this paper, the influence of the width, height, and nose length of the train on the aerodynamic pressure on vertical noise barriers was studied using computational fluid dynamics (CFD) simulations. Results showed that taller and wider trains result in greater aerodynamic loads on noise barriers. Conversely, an increase in the nose length of a train leads to a reduction in such pressure. Using grey relational analysis, correlation of various factors with the train-induced aerodynamic pressure is, from strong to weak: distance to the track center, width, height, and nose length of the train. Building upon the EN 14067-4 calculation model, the shape coefficients of trains with varying geometric characteristics were derived using the simulation data obtained in this study. A modified pressure calculation model was established accounting for the differences in geometric features of HSTs and pressure distribution in the vertical direction of noise barriers and validated using relevant data from the literature.

Effect of Intake Acoustic Reflection on Blade Vibration Characteristics

Recent studies in turbomachinery have shown that the phase of acoustic wave reflection within an intake can have either positive or negative effects on the aeroelastic stability of fan rotor blades. However, the typical flow structures, such as the shock wave, within rotor blade passages with acoustic wave reflection remain unclear. The aim of this research was to address this gap by investigating how these flow structures impact blade aeroelastic stabilities with acoustic wave reflections. The focus of this study was the NASA Rotor 67 blade with an extended intake. Moreover, a bump is incorporated on the shroud at different distances from the fan to reflect acoustic waves of varying phases. Utilizing the energy method, variations in the aerodynamic work density on blade surfaces were calculated under different phases of reflected acoustic waves. Analysis indicates that the spatial position of the shock wave undergoes periodic changes synchronized with the phase of acoustic reflection, marking the first instance of such an observation. This synchronization is identified as the primary factor causing variations in the aeroelastic stability of blades due to acoustic wave reflection, contributing to a deeper understanding of the mechanism behind acoustic flutter. The acoustic–vortex coupling at the blade tip leads to unpredictable variations in unsteady pressures on the blade suction surface, although its effect on blade aeroelastic stabilities is relatively limited compared to that of the shock wave.

Active and passive soil wedges influence on the natural frequency of retaining structures

Studying the behavior of retaining structures has been very important issue due to their large application in civil engineering. An accurate determination of the earth pressure and the natural frequency is elemental for studying the dynamic behavior of these structures. In the most previous investigations, the soil backfill was considered sufficient width as rectangular mass whereas in the real. the backfill behind retaining structures repartitioned as triangular active and passive soil wedges. Rectifying this weakness, this study proposed an analytical model for calculating the natural frequency of retaining structures by considering the triangular active and passive soil failure wedges, which take into account the variation of earth pressure behind retaining structures. The soil wedge causes an increase in the value of natural frequency. It is clarified that the soil wedge has a large influence on the natural frequency of retaining structures. In this regard, the consideration of active and passive soil wedges behind retaining structures plays an important influence in determining of the natural frequency.