This paper introduces a new sensitivity equation for parameter estimation and model updating, which is based on the autocorrelation function (ACF) of dynamic responses. The proposed method provides an exact and linear relationship between variations of structural parameters and variations of autocorrelation function data. The sensitivity equation is derived to formulate an objective function that is subsequently minimized using a least-squares approach. By iteratively minimizing the objective function, the structural parameters are updated to achieve an accurate finite element model. To evaluate the abilities of the proposed method, a three-dimensional jacket-type offshore platform subjected to harmonic loading is numerically simulated. Challenges such as modeling uncertainties, loading and measurement errors, added mass effects, and incomplete measurements are considered in this simulation. The results obtained from this method are compared with those of time-history-based methods. The comparative results reveal the high potential of the proposed method for practical applications with its enhanced sensitivity with respect to structural parameters and improved robustness against experimental uncertainties (up to 15%).
اثر زاویه پسگرایی و سرعت جریان بر مشخصههای آیرودینامیکی بالزن با بال انعطافپذیر در زوایای حمله مختلف با استفاده از آزمون تجربی در تونل باد مادون صوت، در این پژوهش مورد بررسی قرار گرفته است. آزمایشها در اعداد رینولدز 42000 تا 170000 که محدوده پرواز برای پرندگان طبیعی با ابعاد نزدیک به کبوتر است انجام شده است. مدل آزمون از دو بخش صلب (در ریشه) و انعطافپذیر (در نوک) تشکیل شده و حرکت نوسانی بالزدن در آن توسط سامانه الکترومکانیکی تامین شده است. نتایج نشان میدهد افزایش سرعت در بسامدهای بیبعد شده کمتر از 2/0، سبب کاهش نیروی برآی بال شده است. رفتار نمودار ضریب پیشران برحسب سرعت در زوایای حمله صفر تا 6 درجه کاملاً متفاوت از زوایای حمله بیش از 6 درجه است؛ به طوری که در زاویه حمله 3 درجه تغییرات بر حسب سرعت کمتر از 10 درصد بوده اما در زاویه حمله 18 درجه ضریب پیشران با افزایش سرعت از 5 به 20 متر برثانیه، 50 درصد کاهش داشته است. همچنین انعطافپذیری بال سبب شده است تا با افزایش سرعت اختلاف فشار دینامیکی جریان سبب تغییر شکل بال و در نهایت کاهش ضریب برآی بال شود. نیز ساختار جریان از زاویه حمله 9 درجه به بعد به گونهای است که توانایی تولید نیروی پیشران نداشته است.
The increasing demand for antibacterial and biocompatible materials in biomedical applications prompts the development of titanium-copper (Ti-Cu) alloys as promising candidates. These alloys attract wide attention due to their potent antibacterial activity against various bacteria. This study thoroughly reviews the antibacterial properties, biocompatibility, and corrosion performance of Ti-Cu alloys in different circumstances. The effects of copper content, processing routes, surface treatments, and other parameters on antibacterial efficacy, cytocompatibility, osseointegration, and corrosion resistance are analyzed. The investigation spans multiple length scales, examining factors from bulk alloy composition to microstructural features like intermetallic phases and their morphology, distribution, and surface characteristics including topography and wettability. Ultimately, the ongoing challenges associated with Ti-Cu biomedical alloys are critically evaluated, mapping out strategic research directions to fully harness their multifunctional capabilities.
Scraper layout design in Tunnel Boring Machines (TBMs) remains a relatively underexplored aspect of cutterhead configuration, despite its critical influence on excavation efficiency and tool wear mitigation. This study introduces a structured framework for scraper layout classification and geometric design, enabling reproducible, balanced, and adaptable arrangements. A dataset of 228 high-performing TBM projects was analyzed to identify key predictors—Machine Type (MT), Cutterhead Diameter (Dia.), and Ground Condition (GC)—used to train a Classification and Regression Tree (CART) model. The model categorizes layouts into four types: None, Radial, Spoke, and Multi-scheme. Deterministic parametric formulas are then applied to generate scraper arrangements based on coverage width, spacing, overlap, and force symmetry. GC emerged as the most influential predictor (normalized importance = 100%), followed by MT (88.1%) and Dia. (42.6%). The CART model achieved a test accuracy of 71.9%, with Receiver Operating Characteristic (ROC) Area Under the Curve (AUC) values exceeding 0.85 for most classes. Multi-scheme layouts were prevalent in Earth Pressure Balance (EPB) and Slurry machines with Dia. > 6.545 m, while spoke and radial layouts dominated below this threshold, shaped by ground condition. The proposed methodology offers a data-driven alternative to empirical layout practices and demonstrates practical applicability through case studies. It lays the groundwork for intelligent cutterhead configuration and future integration into CAD environments and digital twin platforms.
This study examines the selection of cutterhead opening types (OT) in tunnel boring machines (TBMs) through a data-driven analysis of 257 high-performing TBM projects (defined as those with above-average Monthly Advance Rates), aiming to extract empirical industry best practices. The focus is on identifying opening type configurations that have proven successful across diverse conditions, rather than predicting continuous performance metrics such as penetration rate. The selection of OT—categorized into Sector, Slot, Peripheral Bucket (PBu), and Mixed-type Opening (MOp)—was evaluated against key parameters, including Geological Condition (GC), Machine Type (MT), Diameter (Dia.), and Fine Content (FC). Relative importance analysis identifies GC as the most influential predictor of OT selection (100), followed by MT (81.5), Dia. (77.9), and FC (6.9). Among the evaluated decision tree models, CART emerges as the top-performing algorithm with an accuracy of 82.4 %, while PART achieves 78.3 %, offering concise, interpretable rule-based structures. The derived rules reveal distinct engineering preferences: MOp is favored for large-diameter tunnels (>8.33 m) to manage high material volumes and maintain face stability, whereas Slot and Sector openings dominate in mid-sized tunnels (4.25 to 8.33 m) based on specific GC and MT constraints. Furthermore, narrow openings (opening ratio < 20 %) are identified as critical in bouldery and coarse ground to retain large particles for secondary crushing, while central openings are essential in cohesive soils to mitigate clogging. Ultimately, this research translates complex historical data into a transparent, rule-based decision-support framework, providing the tunneling industry with actionable guidelines for preliminary cutterhead configuration.
