Changes In Dynamic Characteristics Research Articles

A Growth of Hierarchical Autoregression Model for Capturing Individual Differences in Changes of Dynamic Characteristics of Psychological Processes

Several methodological innovations have been advanced in the past decades that combine growth curve models (GCMs) with models of autoregressive (AR) processes. However, most of these approaches do not effectively capitalize on known (e.g., study design-related) information to structure the growth curves into meaningful between- and within-phase changes, while simultaneously accommodating interindividual differences in these intraindividual changes. We propose a Bayesian growth of hierarchical autoregression (GoHiAR) model, which combines AR and GCM to evaluate phase-to-phase changes in multifaceted dynamic characteristics (e.g., baseline, variability, and inertia) as well as individual differences in these changes. This approach allows for drawing conclusions in a way that the proposed data generating mechanisms are in line with the theoretical insights about psychological change and dynamics. Our Bayesian implementation of the GoHiAR model allows for all parameters to be estimated simultaneously. First, we evaluated GoHiAR’s overall estimation accuracy and sampling efficiency, effects of model misspecifications, and sensitivity to effect sizes via a simulation study. Results showed reasonable performance. Then, we applied GoHiAR to an ecological momentary assessment (EMA) study that comprised data from pre-, during, and following an intervention, and investigated changes in the dynamic characteristics of individuals’ psychological well-being (specifically in meaning of life) within and across phases.

Improved real-time [formula omitted] control for aero-engines based on the equilibrium manifold expansion model

This paper investigates the transient performance and disturbance rejection control problem for aero-engines based on the equilibrium manifold expansion (EME) model. Considering the operating characteristics of the aero-engine vary greatly during different flight states, it is difficult to ensure the performance of the aero-engine in different states using a single controller designed offline. To solve this problem, this paper proposes an improved real-time H∞ controller. Through driving the controller to match the changes in dynamic characteristics of the system, the stability and disturbance rejection performance of the system are guaranteed over a wide range effectively. In addition, a dynamic adjustment mechanism is designed for the disturbance rejection parameter in the proposed real-time H∞ controller, which further improves the transient performance of the system. The sufficient conditions to ensure the stability of the system under the designed method are also given. Finally, the effectiveness and superiority of the proposed method are verified through an aero-engine numerical simulation program and a hardware-in-the-loop (HIL) experiment.

The impacts of climate change, early agriculture and internal fluvial dynamics on paleo-flooding episodes in Central China

Floods clustered in episodes are the most prevalent natural disaster worldwide, causing substantial economic and human losses. Although these events are often linked to time-periods of extreme rainstorms and unique atmospheric circulation patterns, the river basin characteristics affected by anthropogenic land use changes could exert a strong influence. However, the way and extent of how land use changes across different time scales affect flooding periods are still unclear, especially considering the historical land use changes. This study uses the Landlab landscape evolution model, coupled with an evapotranspiration model, to investigate the forcing factors for the paleo-flooding trends in the Wei River catchment over the last 5000 years. The results indicate that the flooding period from 4400 to 4000 BP was caused by an increase of 28 % in antecedent moisture content as well as a decrease of 28 % in its spatial variability, which are primarily due to climate change, and that the contribution of land-use change is less than 5 %. The increases of about 14 % and 8 % in main channel sedimentation rate play a leading role in flood generation during the time periods from 3400 to 2800 BP and 2000–1400 BP, respectively. These two periods of increased flooding are primarily caused by the erosional effects of increasing anthropogenic land use, whose contributions range from 33 % to 64 %. Furthermore, based on our modelling results, we suggest that the downstream propagation of the main flooding locations, from the Wei River to the lower reaches of the Yellow River, can be explained by the downstream migrating sediment wave. In conclusion, our simulation results give new insights into the causes of Holocene flooding periods in the middle Yellow River from the perspective of dynamic changes in catchment characteristics, which is helpful to improve regional flood risk management under future climate change and anthropogenic activities.

Robust fractional-order load frequency control for hybrid power system concerning high wind penetration

Hybrid power systems concerning wind farms have witnessed significant dynamic characteristic changes due to unpredicted generation output and integration mode conversion between frequency-sensitive wind plants and non-scheduled ones. This work presents a robust fractional-order load frequency control (LFC) method for a multi-area hybrid power system in the presence of wind penetration uncertainties. To characterize the injection effect of wind farms, the power system is described by a model with an uncertain wind penetration factor in a pre-estimated range. Then, an enhancement of Levy’s identification method is developed to convert this model into a fractional-order reduced structure to design the load frequency controller, which is in a form of fractional-order PID with a filter for ease of engineering implementation. The closed-loop stability is analyzed by the stability boundary locus (SBL) method under different wind penetration levels. It is shown that superior frequency response performance and system robustness can be obtained if the controller is designed in terms of the model with the worse-case wind penetration. Illustrative examples including a three-area hybrid power system under a variety of wind penetration variations are given to show the effectiveness of the proposed method.

Innovative insights into the roasting-driven transformation of volatile compounds and quality markers in flaxseed (Linum usitatissimum L.) oil.

Roasting is essential for developing the characteristic aroma of flaxseed oil (FSO), yet its impact on oil quality remains underexplored. This study employed headspace-gas chromatography-mass spectrometry coupled with multivariate analysis to elucidate the dynamic changes in volatile compounds and quality characteristics of FSO subjected to varying roasting temperatures. Our findings revealed that seven key aroma compounds, identified through the variable importance in the projection scores of partial least square-discrimination analysis models and relative aroma activity value, served as molecular markers indicative of distinct roasting temperatures. These compounds included 2,5-dimethylpyrazine, 2-pentylfuran, (E)-2-pentenal, 2-ethyl-3,6-dimethylpyrazine, heptanal, octanal, and 2-hexenal. Notably, roasting at 200°C was found to enhance oil stability and antioxidant capacity, with phenolic compounds and Maillard reaction products playing synergistic roles in bolstering these qualities. Network analysis further uncovered significant correlations between these key aroma compounds and quality characteristics, offering novel perspectives for assessing FSO quality under diverse roasting conditions. This research not only enriched our understanding of the roasting process's impact on FSO but also provided valuable guidance for the optimization of industrial roasting practices. This study would provide important practical applications in aroma regulation and process optimization of flaxseed oil. .

A Method to Obtain Frequency Response Functions of Operating Mechanical Systems Based on Experimental Modal Analysis and Operational Modal Analysis

The characteristics of a mechanical structure under operating conditions may differ from those in a static state. It is often more desirable to obtain the frequency response function (FRF) of the operating structure in engineering applications. While operational modal analysis (OMA) can estimate modal parameters during operation, it fails to provide mass-normalized mode shapes for FRF synthesis. This paper presents a new method using experimental modal analysis (EMA) to compensate for the absent information in OMA. It categorizes operational mode shapes into changed ones and those that remain the same compared to the static state, applying different scaling techniques accordingly. This method adapts to changes in dynamic characteristics without altering the operating conditions. Stability is emphasized throughout the process. Two examples are provided to verify the method, considering noise and incompleteness in measurement, and disturbances in dynamic properties. The proposed method is proven to be feasible and reliable to capture the changes in operational FRFs.

Age-related changes in cheek skin movement: A case study of Japanese women.

The majority of conventional studies on skin aging have focused on static conditions. However, in daily life, the facial skin we encounter is constantly in motion due to conversational expressions and changes in facial expressions, causing the skin to alter its position and shape, resulting in a dynamic state. Consequently, it is hypothesized that characteristics of aging not apparent in static conditions may be present in the dynamic state of the skin. Therefore, this study investigates age-related changes in dynamic skin characteristics associated with facial expression alterations. A motion capture system measured the dynamic characteristics (delay and stretchiness of skin movement associated with expression) of the cheek skin in response to facial expressions among 86 Japanese women aged between 20 and 69 years. The findings revealed an increase in the delay of cheek skin response to facial expressions (r=0.24, p<0.05) and a decrease in the stretchiness of the lower cheek area with age (r=0.60, p<0.01). An increasing variance in delay and stretchiness within the same age group was also observed with aging. The findings of this study revealed that skin aging encompasses both static characteristics, such as spots, wrinkles, and sagging, traditionally studied in aging research, and dynamic aging characteristics of the skin that emerge in response to facial expression changes. These dynamic aging characteristics could pave the way for the development of new methodologies in skin aging analysis and potentially improve our understanding and treatment of aging impressions that are visually perceptible in daily life but remain unexplored.

Effect of scour on the fatigue life of offshore wind turbines and its prevention through passive structural control

Abstract. Offshore wind turbine (OWT) support structures are exposed to the risk of fatigue damage and scour, and this risk can be effectively mitigated by installing structural control devices such as tuned mass dampers (TMDs). However, time-varying scour altering OWTs' dynamic characteristics has an impact on the TMD design and fatigue life, which has rarely been studied before. In this paper, a simplified modal model is used to investigate the influence of scour and a TMD on the fatigue life evaluation of a 5 MW OWT's support structure, and a traditional method and a newly developed optimization technique are both presented to obtain TMD parameters. This optimization technique aims at finding optimal parameters of the TMD which maximize the fatigue life of a hotspot at the mudline, and the effect of time-varying scour can be considered. This study assumes that the TMD operates in the fore–aft (FA) direction, while the vibration in the side–side (SS) direction is uncontrolled. Results show that scour can decrease the fatigue life by about 24.1 % and that the TMD can effectively suppress vibration and increase the fatigue life. When the scour depth reaches 1.3 times the pile diameter, the TMD with a mass ratio of 1 % can increase the fatigue life of an OWT's support structure by about 64.6 %. Further, it is found that the fatigue life can be extended by 25 % with the TMD optimized by the proposed optimization technique rather than using a traditional design method which does not take the change in dynamic characteristics into account.

Dynamic Characterization of Grease-Lubricated Ball Screws

According to the lubrication characteristics of grease and lubrication mechanism, concerning the Hamrock-Dowson minimum film thickness formula, this paper analyses the trend and size of oil film thickness change of grease-lubricated ball screw sub under different aviation working conditions to identify the lubrication status. ABAQUS software is used to carry out dynamic simulation and the friction coefficient is selected according to the lubrication state and Stribeck curve to define the contact conditions to obtain the friction torque change curve and the fluctuation curve of axial velocity of the nut under different aerospace working conditions. Finally, a test bench is set up to test and calculate the friction torque of grease-lubricated ball screws to analyze the influence of different aviation working conditions on the dynamic characteristics of grease-lubricated ball screws and to investigate the reasons for the change of dynamic characteristics.

Dynamic variation in the aroma characteristics of Rhus chinensis honey at different stages after capping

The ripening characteristics after capping of honey are favourable for improving its quality. However, research on the variation and formation of aroma characteristics of honey in this process is lacking. Therefore, the present study was carried out with different stages of Rhus chinensis honeys (RCHs) after capping and identified 192 volatiles with varying levels of concentration. “Fruity” was the main aroma characteristic of RCHs at different stages after capping, mainly contributed by (E)-β-damascenone. Methyl salicylate might be a potential indicator for differentiating RCHs at different stages after capping. The metabolic pathway analyses revealed that the aroma compounds in RCHs undergo transformation at different stages after capping, which subsequently affects its aroma characteristics formation. This work is the first to study the dynamic changes in honey aroma characteristics after capping from multiple perspectives, and the results are of great significance for understanding the aroma characteristics after capping and quality control of honey.

Impacts of Spatio-Temporal Changes in Anthropogenic Disturbances on Landscape Patterns in the Nandu River Basin, China

We explored the characteristics of landscape pattern (LP) changes in the Nandu River Basin (NRB) and its dynamic response mechanism to anthropogenic disturbance (AD). This is important for ecological protection and for land use decision-making in the basin in the context of the construction of a free trade port. Land use and land cover change (LULCC) data of 1990, 2000, 2010, and 2020 were analyzed with the help of the LP index, moving window method, hemeroby index, geo-information atlas, and geographic information system (GIS) spatial analysis to reveal the dynamic changes in LP characteristics in the NRB. Furthermore, this paper discusses into the correlation between LP and AD. The results indicate that over the past three decades, the NRB showed a staggered LP, dominated by forestland and cropland, whose total area has decreased by 25.27 km2 and 62.75 km2, respectively. On the other hand, the built-up land increased by 91.37%. The overall landscape fragmentation, landscape patch homogeneity, and landscape diversity have increased in the NRB. AD is the main reason for the dramatic changes in the LP of urban agglomerations centered in Haikou city. The area of minor disturbance (over 34%) occupies the largest proportion of the land, followed by higher (about 13~25%) and moderate disturbances (about 17~22%). The area of minor and strong disturbances has increased significantly, whereas those of moderate and higher disturbances have significantly decreased. The spatial distribution pattern of AD is gradually increasing from the southwest (natural landscape) to the northeast (human landscape). A transition in areas of low disturbance levels to higher levels is obvious. The area of the atlas that has transitioned from “minor → lighter disturbance (12)” and “higher → minor disturbance (41)” changed changed most significantly during 2000 to 2010 and from 2010 to 2020, occupying 26.79% and 11.99% of the transfer atlas, respectively. All regions encountering disturbances were significantly correlated with the largest patch index (LPI) from 1990 to 2020. The overall AD in the NRB has increased, especially in Haikou. Urbanization is the main factor for an increase in AD. The ecological and environmental management and monitoring in the basin need to be strengthened.

Dynamic changes in metabolomics and flavoromics during industrial scale fermentation of Chinese traditional soy sauce

Flavor substances are crucial to the quality of soy sauce and closely related to the intermediate metabolites. This study systematically explored the dynamic changes in physicochemical characteristics, metabolomics and flavoromics during traditional Chinese soy sauce fermentation. The results indicated that the amino acid nitrogen gradually increased to 0.95 g/100 mL on the 13th day and then stabilized, and the changes of reducing sugars increased to 66.40 mg/mL on the 7th day and then slowly decreased. A total of 90 volatile compounds and 1172 non-volatile metabolites were detected. In the early fermentation period (1–7 day), alcohols, aldehydes and ketones were the main volatile compounds, but as fermentation proceeded, phenols and esters gradually accumulated. The total content of volatile compounds, mainly alcohols and phenols, reached the highest value on the 23rd day. Non-volatile metabolites were mainly amino acids, organic acids, lipids and carbohydrates, and the content and types of varied with fermentation time. KEGG analysis indicates there were significant changes in the proline and arginine metabolism in the middle and late periods (7–28 day) compared to the early fermentation period. Correlation analysis indicating a delicate balance between the transformation of metabolites and the formation of volatile compounds in traditional Chinese soy sauce.

Dynamics of Berry Characteristics, Biochemical Composition, and Physiological Responses Across Ripening Stages: Investigating the Impact of Pollinizer Varieties on Physiological Femaleness in Bozcaada Çavuşu (Vitis vinifera L. cv)

AbstractUnderstanding the dynamic changes in grape characteristics during ripening is crucial for enhancing grape quality, which, in turn, influences overall viticulture practices. This study aimed to investigate the temporal and cultivar-specific variations in grape characteristics, focusing on BAs, phenolic compounds, antioxidant enzymes, and organic acids. Our results revealed that Bozcaada Çavuşu*Kuntra and Kuntra grapes exhibited the most significant growth in size, weight, and maturity index at the final developmental stage (EL-38), while Vasilâki showed a nuanced maturation pattern with significant increases in berry width but not weight. Across all varieties, the highest maturity index and Total Soluble Solids percentages were observed at EL-38. The investigation of BAs revealed a significant decrease in Put levels from 2.62 at EL-32 to 2.04 mg L−1 at EL-38, contrasting with an increasing trend in Agm concentrations from 0.25 at EL-29 to 0.37 mg L−1 at EL-38. Bozcaada Çavuşu*Kuntra stood out with the highest Cad concentration at 2.96 mg L−1. The analysis of phenolic compounds highlighted a distinct temporal pattern for gallic acid, increasing from 1.60 at EL-29 to 3.77 g L−1 at EL-32 and maintaining stability at 3.74 g L−1 at EL-38. Bozcaada Çavuşu*Vasilâki consistently exhibited higher concentrations of phenolic compounds, such as epicatechin (5.69 g L−1) and tyrosol (7.00 g L−1). Antioxidant enzymes like catalase and superoxide dismutase in grape cultivars showed significant temporal variations, indicating a dynamic oxidative stress response during berry ripening. Catalase activity decreased from 14.04 to 11.20 EU/gr berry between EL-29 and EL-38. The multifaceted regulation of superoxide dismutase by sampling time and cultivar highlighted the complexity of antioxidant dynamics in grapevine physiology. In conclusion, this comprehensive study sheds light on the intricate interplay of temporal and cultivar-specific factors influencing grape characteristics, providing valuable insights for optimizing viticulture practices and enhancing overall grape quality.

Dynamic characteristics changes of masonry arches exposed to elevated temperature

In this study, the changes in the dynamic characteristics of masonry arches exposed to elevated temperatures were investigated experimentally and numerically. Firstly, the material properties were analyzed at different temperatures, ranging from 200°C to 800°C, through experimental tests. The constructed arch specimens were then subjected to heat to investigate the effects of elevated temperatures on their dynamic characteristics. Ambient vibration tests were performed before and after heating to identify natural frequencies and mode shapes. Furthermore, numerical models of the arches were developed, and a model updating procedure was implemented to minimize the differences between the numerical and experimental data. The findings indicated that elevated temperatures led to notable decreases in the compressive strengths of both the stone and the mortar. This decrease significantly degraded the stiffness of the masonry arch samples, consequently having a profound effect on their dynamic properties.

Antibiotic resistance, biofilm formation, and molecular epidemiology of Staphylococcus aureus in a tertiary hospital in Xiangyang, China.

Staphylococcus aureus is a common clinical pathogen that causes various human infections. The aim of this study was to investigate the antibiotic susceptibility pattern, molecular epidemiological characteristics, and biofilm formation ability of S. aureus isolates from clinical specimens in Xiangyang and to analyze the correlation among them. A total of 111 non-duplicate S. aureus isolates were collected from the Affiliated Hospital of Hubei University of Arts and Science. All isolates were tested for antibacterial susceptibility. Methicillin-resistant S. aureus (MRSA) was identified by the mecA gene PCR amplification. All isolates were analyzed to determine their biofilm-forming ability using the microplate method. The biofilm-related gene was determined using PCR. SCCmec, MLST, and spa types of MRSA strains were performed to ascertain the molecular characteristics. Among the 111 S. aureus isolates, 45 (40.5%) and 66 (59.5%) were MRSA and MSSA, respectively. The resistance of MRSA strains to the tested antibiotics was significantly stronger than that of MSSA strains. All isolates were able to produce biofilm with levels ranging from strong (28.9%, 18.2%), moderate (62.2%, 62.1%), to weak (8.9%, 19.7%). Strong biofilm formation was observed in MRSA strains than in MSSA strains, based on percentages. There were dynamic changes in molecular epidemic characteristics of MRSA isolates in Xiangyang. SCCmecIVa-ST22-t309, SCCmecIVa-ST59-t437, and SCCmecIVa-ST5-t2460 were currently the main epidemic clones in this region. SCCmecIVa-ST5-t2460 and SCCmecIVa/III-ST22-t309 have stronger antibiotic resistance than SCCmecIVa-ST59-t437 strains, with resistance to 6 ~ 8 detected non-β-lactam antibiotics. The molecular epidemic and resistance attributes of S. aureus should be timely monitored, and effective measures should be adopted to control the clinical infection and spread of the bacteria.

Mapping Extracellular Space Features of Viral Encephalitis to Evaluate the Proficiency of Anti-Viral Drugs.

The extracellular space (ECS) is an important barrier against viral attack on brain cells, and dynamic changes in ECS microstructure characteristics are closely related to the progression of viral encephalitis in the brain and the efficacy of antiviral drugs. However, mapping the precise morphological and rheological features of the ECS in viral encephalitis is still challenging so far. Here, a robust approach is developed using single-particle diffusional fingerprinting of quantum dots combined with machine learning to map ECS features in the brain and predict the efficacy of antiviral encephalitis drugs. These results demonstrated that this approach can characterize the microrheology and geometry of the brain ECS at different stages of viral infection and identify subtle changes induced by different drug treatments. This approach provides a potential platform for drug proficiency assessment and is expected to offer a reliable basis for the clinical translation of drugs.

Designing a Model Predictive Controller for Displacement Control of Axial Piston Pump

Variable displacement hydraulic pumps are widely used for energy efficiency, and they often have a mechanical feedback mechanism to ensure target tracking control performance and stability of tilt angle control. Furthermore, there are many examples which add electronic control to realize higher tracking control performance. However, in such cases, the control performance is significantly affected by the dynamic characteristics of the mechanical feedback mechanism, and this problem prevent its widespread use. Additionally, tilt angle control is susceptible to changes in dynamic characteristics and load pressure depending on the operating point, and there are constraints on the tilt angle. Hence, high control performance cannot be obtained without considering these nonlinearities. In this study, the variable displacement pump without mechanical feedback mechanism is focused on, and the objective of this study is to design a displacement control system for a hydraulic pump based on a model predictive control (MPC) that can consider various constraints on the design step. An adaptive system, which handles changes in dynamic characteristics and the effects of load pressure, is introduced. Additionally, the control performance of adaptive MPC is compared to adaptive model matching-based MPC with inverse optimization that can optimally design the weight matrices of the evaluation function without trial and error. Furthermore, in order to improve the transient response, a variable control input constraints are added in these two control systems. Experimental results of control performance have shown that the proposed method achieved a high tracking performance and short settling time, which confirmed the effectiveness of the variable control input constraints.

Dynamic changes in carbohydrate components and the bacterial community during the ensiling of wilted and unwilted sweet sorghum.

Sweet sorghum can be used to produce a substantial quantity of biofuel due to its high biological yield and high carbohydrate content. In this study, we investigated the dynamic changes in fermentation characteristics, carbohydrate components, and the bacterial community during the ensiling of wilted and unwilted sweet sorghum. The results revealed a rapid fermentation pattern and high-quality fermentation quality in wilted and unwilted sweet sorghum, wherein lactic acid, and acetic acid accumulated and stabilized during the initial 9 days of ensiling, with the pH values less than 4.2, until 60 days of ensiling. We found that the ensiling of sweet sorghum involved the degradation (5% ~ 10%) of neutral detergent fiber (NDF) and hemicellulose and that the degradation of NDF fit a first-order exponential decay model. A shift in dominance from Lactococcus to Lactobacillus occurred before the first 9 days of ensiling, and the abundance of Lactobacillus (r = -0.68, p < 0.001) was negatively correlated with the NDF content. The relative abundances of Lactobacillus in wilted and unwilted sweet sorghum after ensiling for 60 days were 76.30 and 93.49%, respectively, and relatively high fermentation quality was obtained. In summary, ensiling is proposed as a biological pretreatment for sweet sorghum for subsequent biofuel production, and unlike other materials, sweet sorghum quickly achieves good fermentation quality and has great potential for bioresource production.

Conceptualizing psychological well‐being as a dynamic process: Implications for research on mobile health interventions

AbstractWe introduce a theoretical framework for conceptualizing Psychological Well‐Being (PWB) as a process that unfolds over short and longer time‐scales. We argue that this framework can be especially useful for studying the change mechanisms in PWB within the context of mobile Health (mHealth) interventions. Four lines of research are considered within this framework to inform the scientific exploration of PWB in the context of mHealth interventions. First, we explore key dynamic characteristics of change in PWB functioning. Second, we discuss PWB intervention response as a learning process (i.e., meaningful and transformational changes in state), reflected as change in key dynamic characteristics of PWB. Third, we explain mechanisms of change in PWB intervention practices through an underlying process of skill development. Fourth, we discuss intervention response heterogeneity within this framework. The approach we outline is intended to articulate currently unanswered, process‐oriented research questions about PWB interventions, how they work, and a methodological path forward for exploring them.

Seismic vulnerability assessment of historical minarets in Cairo

IntroductionMasonry minarets in Old Cairo are highly susceptible to earthquake damage, particularly those not designed or updated to withstand seismic loads. Therefore, regular monitoring is necessary to ensure their safety and detect any deterioration or reduction in seismic performance. The direct loss of a minaret can lead to the collapse or severe damage to the structure itself. The cascading impacts of partial or complete minaret failure can have significant consequences for the immediate vicinity and the broader community. By studying the effects of earthquakes on minarets and developing mitigation strategies, countries can take proactive measures to protect these structures and ensure the safety of people.ObjectiveThis study focuses on a specific type of Islamic architecture: the historic minarets in Cairo. The research aims to evaluate the seismic vulnerability of eight cultural heritage minarets in Cairo, identifying the parameters influencing their seismic behaviour and susceptibility to earthquake damage.MethodsThe research utilizes empirical seismic vulnerability methods and ambient vibration measurements on eight minarets. An empirical approach compatible with the nature and style of the minarets is employed to evaluate their vulnerability using index values and curves. The method's validity is assessed, and areas of conformity and limitations are identified. Ambient vibration tests (AVTs) are also conducted using a temporary seismic network installed at various heights inside each minaret to determine their dynamic characteristics.ResultsThe seismic vulnerability Index (I_V) is calculated for the selected minarets based on the state of each vulnerability parameter. The contribution of each parameter to the final I_V values of the minarets are presented. Vulnerability curves are developed for each minaret, interpreting the conventional vulnerability indexes in terms of mean damage grades for seismic events with varying intensity on the EMS-98 scale. These mean damage grades can also indicate the expected damage levels of structural and non-structural minaret elements for events with different seismic intensity levels. AVTs are conducted at various heights on the selected minarets, and the dynamic characteristics are extracted from the recorded data. Variations in these characteristics are considered significant for structural health monitoring analysis. The peak-picking method is employed to directly extract each minaret's natural frequencies and mode shapes, as changes in dynamic characteristics are relevant to health monitoring analyses.ConclusionsThe recent study examined the seismic vulnerability assessment of eight masonry minarets in the historic Old Cairo district. The assessment revealed vulnerability index values ranging from 10.3 to 26.1, indicating a concerning susceptibility to seismic events among these structures. Vulnerability curves were constructed for each minaret, visually representing potential damage scenarios across different levels of the EMS-98 intensity scale. These outcomes are significant as they facilitate prioritizing interventions to safeguard the most vulnerable minarets. Additionally, a novel empirical period equation was introduced to estimate the fundamental period of minarets in Old Cairo based on their heights. The equation was validated against field measurements and data from the literature. The study is limited by its focus on a specific category of minarets, specifically the historical masonry minarets in Old Cairo. Furthermore, limitations arise from the need for detailed finite element models to capture these minarets' dynamic responses accurately. Therefore, ongoing research involves the development of detailed finite element models and calibrating fundamental periods for the selected minarets. The anticipated results hold the potential to enhance our understanding of the structural dynamics of historical minarets, ultimately guiding the formulation of tailored seismic retrofitting and preservation strategies. These strategies, aimed at preserving these cherished cultural heritage assets, represent our collective commitment to ensure the endurance of these timeless landmarks for future generations.