DSpace collection: 期刊論文

Automatic BIM-Based Formwork Quantification System

title: Automatic BIM-Based Formwork Quantification System abstract: Building information modeling (BIM) has significantly enhanced the efficiency of quantity takeoff in construction projects. However, existing BIM-based tools for formwork quantification often lack critical functionalities particularly in handling element intersections, irregular geometries, and practical construction considerations. In addition, many current systems rely on manual reprocessing or require multiple software platforms to reflect updates to the BIM model, which limits their effectiveness in dynamic project environments characterized by frequent design revisions. This study presents the development of a fully automated BIM-based formwork quantification system (BFQS), created in collaboration with a general contractor and validated through real-world implementation. The system focuses specifically on quantifying formwork areas. BFQS operates within a single, integrated Revit-based platform and enables automatic, real-time updates of formwork quantities in both two-dimensional (2D) and three-dimensional (3D) environments. It incorporates advanced modeling logic to accommodate diverse on-site conditions, including stair formwork, intersection deductions, small openings, soft intersections, irregular geometries, and the exclusion of nonformwork elements such as lightweight partitions. By maintaining continuous synchronization with the BIM model, the system effectively facilitates project workflows where frequent design revisions occur, thereby enhancing accuracy and responsiveness throughout the design and construction phases. BFQS addresses key limitations of previous tools by incorporating practical parameter settings that reflect real-world construction conditions, contributing meaningfully to the advancement of BIM-based automation in formwork estimation.

Integration of AR and deep learning-based image classification using CNN for construction project monitoring.

title: Integration of AR and deep learning-based image classification using CNN for construction project monitoring. abstract: With manual update, progress monitoring of a construction project is notably challenging due to its labor-intensive and time-consuming nature. The issue of manual update has been proposed to be alleviated by automatic update, but most existing AI-based progress tracking approaches are based on counting the elements finished. As a result, they cannot accurately reflect actual progress status to the project management. This research aims to develop a system that updates the progress of the construction project by effectively identifying both the construction category and operational stage. It is achieved by systematically integrating the techniques of Augmented Reality (AR) and deep learning–based image classification with convolutional neural networks (CNNs). The proposed scheme enables real-time data capture, facilitating comprehensive progress evaluation across multiple project locations. Its effectiveness is demonstrated using a case study of an interior finishing project for a building in Tamkang University, Taiwan. It reveals that the proposed system accurately identifies the construction category and operational stage based on the materials applied, enabling precise tracking of the progress. The results confirm that the proposed scheme significantly enhances the accuracy in construction progress monitoring, avoiding manual inspection and minimizing discrepancies between the planned and actual progress.

Ameliorating the Profound Gender Wage Gap in the AEC Industry among the APEC members

title: Ameliorating the Profound Gender Wage Gap in the AEC Industry among the APEC members abstract: This research aims to discover the challenges and propose effective strategies to empower women by ameliorating the gender wage gap in the architecture, engineering and construction (AEC) industry among the APEC members. The study applied document review analysis and conducted focus group discussions, where thirty female professionals in the AEC industry from APEC participated. The results report four challenges contributing to the gender wage gap, namely gender bias and stereotyping, work-family conflicts, physical strength and lack of transparency. Based on the challenges, the study suggests several key strategies focusing on women's participation in the AEC industry, encouraging gender-friendly workplaces, healthy and safe workplaces, and fair career development opportunities to reduce the gender wage gap effectively. The findings suggest that by increasing awareness of the value of women's involvement in the AEC industry, pragmatic policies should be formulated for APEC members to break down the barriers to the gender wage gap.

Experimental study on the internal structure and physical properties of rock-avalanche deposits

title: Experimental study on the internal structure and physical properties of rock-avalanche deposits

Mechanical behavior assessment of a deep geological repository in the Kinmen Granite using Particle Flow Code

title: Mechanical behavior assessment of a deep geological repository in the Kinmen Granite using Particle Flow Code abstract: Mechanical stability of underground geological disposal openings for radioactive wastes is a concern because excavated surfaces experience elevated or lowered stress concentration, leading to failure post excavation. The PFC (Particle Flow Code) model, applied to the Kinmen Granite (Taiwan) in this study, reveals that the crack initiation and damage stresses are 0.4 UCS and 0.8 UCS, respectively. Simulated acoustic emission events increase near peak strength, accompanied by clustering of cracks. The input parameters for the PFC were numerically calibrated using laboratory experimental stress–strain curves. A key finding of this study is that the random bond-strength PFC model better characterises the stress-strain behaviour and brittle failure of the Kinmen Granite compared to uniform bond-strength PFC model. Triangular tensile failure zones arise near the spring line of the deposition tunnel post excavation. Thereafter, when the deposition hole is created below the tunnel, much of the contact force fails to reach its top due to the shelter effect from the wider tunnel. Low contact forces appear at the top quarter of the deposition hole, which will likely promote spalling (tensile failure) in this part and near the spring line of the overlying tunnel. This observation agrees with the Aspo Hard Rock field tests.

耦合橋梁結構之等值靜力風載重

title: 耦合橋梁結構之等值靜力風載重 abstract: 現代橋梁著重於美學設計，特殊幾何線型往往導致橋梁結構耦合特性更加顯著。常見的等值靜力風載重計算方式在共振部分大都不考慮振態間相關性，較不適用。本文旨在為耦合結構提供一合適的風載重計算方法。文章包含兩部分，第一部分介紹本研究所提出之靜力風載重計算方式，該方法以單一特定位置的位移極值反應為目標，是一基於散漫振動理論之率域方法，亦可方便的藉由顫振導數考慮橋梁之氣彈影響。第二部分為驗證部分，本文中依據結構耦合程度高低選定兩座橋梁結構做為分析案例，兩案例結果均顯示，本文所提出等值靜力風載重可以良好重現橋梁的動態極值位移反應。

人行拱橋顫振與抖振分析

title: 人行拱橋顫振與抖振分析 abstract: 長跨徑人行拱橋近年來深受工程師青睞，此類型之橋梁除了滿足交通需求外，更扮演當地景觀地標的角色。因為人行拱橋的橋面板較窄，大多採用單拱設計，而單拱構造缺乏側向支撐，拱橋順風向之氣動力反應也越趨明顯。基於此，本文建立一數值分析模式，以主樑斷面及橋拱斷面之顫振導數及風力係數為基礎，推導人行拱橋整體結構之顫振與抖振理論。並採用兩範例來探討加入橋拱風力對整體顫振臨界風速與抖振位移反應影響。結果顯示，橋梁顫振之臨界風速主要受主樑氣動力行為控制，橋拱順風向顫振導數對顫振影響並不顯著。抖振分析方面，兩例之計算結果都顯示拱風力對拱及主樑垂直向反應影響不大，但對於順風向及扭轉向反應有顯著影響。當橋面高度之平均風速 60 m/s 時，加入橋拱風力對第一範例中主樑順風向與扭轉向之抖振位移反應分別提高 1.9% 及 44.11%；對第二範例則分別提升了 11.99% 及 133%。由於影響顯著，因此分析時須詳加考慮。

Serviceability performance of piled raft foundations under vertical loads in clayey and sandy soils

title: Serviceability performance of piled raft foundations under vertical loads in clayey and sandy soils abstract: This study investigated the serviceability performance of piled raft foundations (or combined pile-raft foundations, CPRF) in various soils using three-dimensional (3D) finite element analysis. The piled raft foundation was assumed to be embedded respectively in homogeneous clayey soils and sandy soils under vertical loading. The displacements and reactions of the piles were carefully observed. In comparing the influences of soil stiffness, raft width, pile-to-pile spacing distance, and pile length, it was found that the embedment depth of the foundation could significantly affect the serviceability of the piles. For embedment depths ranging from 0 m to 12 m, the pile loads can be reduced by approximately 40 % to 60 % of the foundation load, depending on the number of piles involved. The displacements of piled raft foundations in clays decrease with increased embedment depth. However, the effects of embedment depth on foundation displacements are smaller in sands. Furthermore, the load ratio of the piles and the displacement ratio of the CPRF were calculated to demonstrate their dependence on the slenderness ratio of the piles and the number of piles. Both ratios aligned with the guidelines the International Society for Soil Mechanics and Geotechnical Engineering (ISSMGE) proposed for CPRF systems. Notably, attention is drawn to the depth of raft embedment, as it significantly influences pile responses.

A study on subsoil and pile reactions of embedded piled raft foundations in sandy soils under vertical loads

title: A study on subsoil and pile reactions of embedded piled raft foundations in sandy soils under vertical loads abstract: This study investigated the load-settlement mechanism of embedded piled raft foundations in sandy soils (ranging from loose to low medium dense sands) under vertically uniform loads through a series of three-dimensional finite element analyses. The foundation model comprises a square concrete raft, varying in width from 16 to 36 m, and embedded at depths of 8 and 12 m from the ground surface. Concrete piles with a diameter of 1 m and lengths of 20 m and 30 m were installed beneath the raft. The foundation was located in homogeneous sands with shear wave velocities ranging from 150 to 210 m/s. Consequently, the modulus of subgrade reaction of the subsoil and the coefficient of pile reaction were both reported. This study examined and presented alternative dimensionless measures of pile displacements, pile reactions, and corresponding coefficients of pile reactions to facilitate hand calculations. Optimized correlations were suggested using box plots and regression analyses for the dimensionless measures with the non-dimensional design parameters of the foundation. Upon verifying the proposed suggestions on a sample example, we conclude that the proposed method offers a preliminary calculation tool for the design of piled raft foundation design in the studied sands.

A closed form formula for equity valuation model based on differential equation

title: A closed form formula for equity valuation model based on differential equation abstract: The valuation of intrinsic value is the cornerstone of value investing. When shareholders purchase a company’s stock, they are essentially buying claims to its future earnings and shareholder equity. Two main approaches, income-based and asset-based, have been developed to value equities. However, these approaches focus solely on either the company’s earnings or its shareholder equity. To overcome these limitations, the Growth Valuation Model (GVM) was developed, which incorporates both income and asset-based aspects. While the GVM model has the advantage of a closed-form solution, it still relies on a discrete infinite series, a common limitation of equity valuation models. In contrast, continuous differential equations have been successfully employed to develop a variety of option pricing models. However, there is a scarcity of equity valuation models derived using continuous differential equations, which is a gap in the current financial modeling landscape. This paper addresses this gap by developing a theoretical equity valuation model, the Continuous Growth Value Model (CGVM), based on a continuous differential equation, and deriving its closed-form solution. Our study concludes: (1) The GVM and CGVM models are developed under three discrete-typed and three continuous-typed assumptions, respectively. Therefore, they can be considered as the discrete and continuous versions of a valuation approach based on the same core principle: mean reversion of return on equity (ROE). (2) The reciprocal of the exponential decay rate in CGVM plays a similar role to the growth coefficient in GVM. (3) The theoretical curves between ROE and P/B ratio of CGVM and GVM are close to each other, and when ROE equals the required return rate, both models will have a P/B ratio of 1.0. (4) Only when the current ROE is greater than the required return rate, the persistence of ROE does have a positive effect on intrinsic value.

Application of boundary integral quadrature method to torsion problems of an isotropic bar containing edge cracks

title: Application of boundary integral quadrature method to torsion problems of an isotropic bar containing edge cracks abstract: Regarding the Saint-Venant torsion problem of elastic cylindrical bar containing edge cracks, the boundary integral quadrature method (BIQM) in conjunction with the dual formula is employed to solve the stress function. In comparison with the conventional dual boundary element method (BEM), the present method is not required to generate the mesh. To achieve this advantage, the parametric representation for the boundary contour and the Gaussian quadrature for the boundary integral play important roles in the present method. When the collocation point is located on the ordinary boundary, the original adaptive exact solution is used to skillfully determine the singular integral in the Cauchy principal value sense. When the collocation point is located on the crack, the corresponding adaptive exact solution is rederived by using the linear combination of harmonic basis of elliptical coordinates. To realize the effect upon the elastic cylinder due to the crack, the torsional rigidity of the cross-section and the stress intensity factor (SIF) at the crack tip are considered to calculate. To conveniently determine the torsional rigidity, the formula is transformed into the form of the boundary quadrature of the boundary density. To the computation of the SIF, the corresponding boundary data on the boundary point that is the most nearly the crack tip is adopted. To check the validity of present results, the conventional dual BEM is adopted to examine those results. Finally, 3 elastic cylindrical bars of different cross-sections are considered. Two of them are circular cross-sections with a radial edge crack and a slant edge crack and the other is an elliptical cross-section with two edge cracks.

Comparison of the results of different types of testing piles with static load to predict the load capacity of piles

title: Comparison of the results of different types of testing piles with static load to predict the load capacity of piles abstract: This paper presents the results of four full-scale static pile load tests that were performed at a site in Astana, Kazakhstan that is underlain by problematic soils. In each test, the bored pile measured 1000 mm in diameter and had a length of 31.5 m. Two of the four static pile load tests were of the standard "top-down" variety. One of these tests was performed in accordance with ASTM D 1143-07; the other was performed in accordance with GOST 5686.2020. The remaining two static pile load tests were bi-directional tests that used an Osterberg ("O") cell. For both types of static pile load tests the results were in good agreement with each other. Comparing the top-down static pile load test results, the ratio of the load in the former to the load in the latter was 1.1 at fixed settlements based on the standard methods tested. Four empirical methods were next applied to the results of these tests and the resulting ultimate capacities compared against the results of the aforementioned four static pile load tests.

An approximate numerical analysis of rafts and piled rafts foundation

title: An approximate numerical analysis of rafts and piled rafts foundation abstract: The load distribution and deformation of rafts and piled rafts were investigated by an analytical and numerical studies. Special attention is given to the improved analytical method (MEGA piles) proposed by considering raft-pile flexibility and soil-pile nonlinearity. The response of raft, a three-dimensional, thin-plate substructure that bears on the soil, is analyzed by flat shell approach by combining a membrane element with a Reissner-Mindlin plate element. An improved analytical method is also developed for the design of piled raft. A series of numerical analyses on piled raft were performed for different head connected conditions, asymmetric geometry of raft, raft flexibility, pile diameters. The proposed method has been verified by comparing the results with other numerical methods and a field case study. Through comparative studies, it is found that the proposed method represents a significant improvement in the prediction of piled raft load sharing and settlement behavior.

A two-dimensional hyperbolic spring model for mat foundation in clays subjected to vertical load

title: A two-dimensional hyperbolic spring model for mat foundation in clays subjected to vertical load abstract: This study proposes a two-dimensional hyperbolic soil spring model for mat foundations in clays subjected to vertically uniform loads to simplify the complexity of three-dimensional finite element analysis on mat foundations. The solutions from three-dimensional finite element analysis were examined to determine the hyperbolic model parameters of the soil springs underneath the slab. Utilizing these model parameters, normalized functions across the middle section of the mat were obtained. The solutions from the proposed model, along with the approximate finite difference analysis of the mat in clays under vertical load, were found to be consistent with those from the three-dimensional finite element analysis. The authors conclude that the proposed method can serve as an alternative for the preliminary design of mat foundations.

Dimensionless reaction coefficients for embedded piled raft foundations in soft clays under vertical loads

title: Dimensionless reaction coefficients for embedded piled raft foundations in soft clays under vertical loads abstract: Although three-dimensional finite-element analysis has been introduced to foundation design for years, simplified computer-based calculations based on the spring analogy of soils and structural elements are also frequently used in many engineering projects. Using coefficients of subgrade reactions and pile stiffness is a straightforward way to design and analyze a piled raft foundation. This paper discusses the determination of the coefficients of pile reactions for embedded piled raft foundations in soft clays subjected to vertically uniform loads through a series of finite-element analyses. The geologic property was assumed to be composed of homogeneous soft clays with the shear-wave velocities varying at 100–140 m/s. The foundations with a square raft ranging from 16 to 36 m and embedment depths of 8 and 12 m were studied. Load intensity approximating 1.5 times the excavated soil pressures was considered where the maximum uniform load was applied to the foundation. The foundation settlements and reactions of the piles were obtained first from a three-dimensional finite-element analysis. For design convenience, the dimensionless pile displacements, pile reactions, and coefficients of pile reactions were developed and presented in plots. The embedment depth-to-raft size ratio, pile slenderness ratio, and pile-to-pile spacing distance-to-pile diameter ratio were examined to find their optimized correlation. Finally, a design example was given to verify the proposed suggestions. We conclude that the proposed method can be an alternative to the piled raft foundation design.

營建工地影像生成文字摘要系統之開發與應用：以工地安全缺失摘要生成為例

title: 營建工地影像生成文字摘要系統之開發與應用：以工地安全缺失摘要生成為例 abstract: 本研究開發了一套基於生成式人工智慧的「營建工地影像生成文字摘要系統」，透過整合多模態模型、大語言模型和圖像檢索 RAG 技術，實現工地安全影像的智能分析與管理。研究團隊建立了包含1,373筆的工安缺失影像資料集，並開發出能自動分析工地照片並生成專業摘要的AI引擎，該引擎可產生包含場景描述、工安缺失、造成原因以及違反法規等完整資訊。系統採用台灣本土優化的 Llama-3-Taiwan 作為大語言模型，結合圖像檢索 RAG技術提升專業知識的準確性。實測結果顯示，系統在場景描述正確性及缺失內容正確性方面表現優異，特別是在法規檢索方面較其他AI 模型展現出顯著優勢。研究成果不僅提供了便捷的工地影像管理與分析工具，更為工程知識的累積與傳承提供創新解決方案。透過API 的佈署，本系統可與既有的工地管理系統整合，為推動智慧工地的發展奠定重要基礎。

鋼構吊裝混合實境多人連線演練系統研發

title: 鋼構吊裝混合實境多人連線演練系統研發 abstract: 本研究旨在開發一套「鋼結構吊裝作業多人連線演練系統」，以提升混合實境技術在營建工程現場應用的可行性，並探討其潛在挑戰。該系統透過虛實整合的數位手段，模擬鋼結構吊裝作業，讓多位使用者能同時參與，進行協同操作與演練。此系統的設計考量了現場實際操作需求，旨在提供一個安全且高效的訓練環境，讓施工人員熟悉吊裝流程，提升團隊協作能力，並減少實際操作中的風險。此外，透過混合實境技術，使用者可以在虛擬環境中體驗真實的施工場景，進一步理解各項操作細節。本研究的成果顯示，該系統在提升施工人員技能培訓方面具有顯著成效，為未來混合實境技術在營建領域的應用提供了實質參考。

Determination of Multiple-target Equivalent Static Wind Load of Large-span Roof Structures based on Clustering Analysis Techniques

title: Determination of Multiple-target Equivalent Static Wind Load of Large-span Roof Structures based on Clustering Analysis Techniques abstract: Spatial structures in modern society exhibit a city’s distinguishing features and show its strength in building technology. Large-span roof structures are mostly seen among spatial structures for various activities. Large-span roof structures are usually sensitive to wind loads due to their lightness in materials and curved geometric appearance. However, spatial structures are generally designed with many structural members, making it challenging to determine adequate load distributions for structural safety analysis. This paper intends to introduce the concept of the multiple-target equivalent static wind loads and to demonstrate how to reduce the heavy computational burden when the structural designer needs to consider multiple loading effects of the target structure. The wind tunnel test of an elliptical-shaped stadium structure with a flat roof is first conducted to show the fundamental aerodynamic characteristics. The methodologies of the background-component wind force based on the load-response-correlation (LRC) method and the resonant-component wind force based on the inertial force method are then introduced for the specification of single-target equivalent static wind loads. Finally, the clustering analysis technique is adopted to explain the concept of the multiple-target equal static wind loads. A decay index is proposed to indicate how the clustering technique improves the specification of equivalent static wind loads.

Exploring the growth value equity valuation model with data visualization

title: Exploring the growth value equity valuation model with data visualization abstract: The Growth Value Model (GVM) proposed theoretical closed form formulas consisting of Return on Equity (ROE) and the Price-to-Book value ratio (P/B) for fair stock prices and expected rates of return. Although regression analysis can be employed to verify these theoretical closed form formulas, they cannot be explored by classical quintile or decile sorting approaches with intuition due to the essence of multi-factors and dynamical processes. This article uses visualization techniques to help intuitively explore GVM. The discerning findings and contributions of this paper is that we put forward the concept of the smart frontier, which can be regarded as the reasonable lower limit of P/B at a specific ROE by exploring fair P/B with ROE-P/B 2D dynamical process visualization. The coefficients in the formula can be determined by the quantile regression analysis with market data. The moving paths of the ROE and P/B in the current quarter and the subsequent quarters show that the portfolios at the lower right of the curve approaches this curve and stagnates here after the portfolios are formed. Furthermore, exploring expected rates of return with ROE-P/B-Return 3D dynamical process visualization, the results show that the data outside of the lower right edge of the “smart frontier” has positive quarterly return rates not only in the t + 1 quarter but also in the t + 2 quarter. The farther away the data in the t quarter is from the “smart frontier”, the larger the return rates in the t + 1 and t + 2 quarter.

Analytical study for numerical instability of steady-state heat conduction problems in exchanger tubes using degenerate kernels in the null-field boundary integral equation method

title: Analytical study for numerical instability of steady-state heat conduction problems in exchanger tubes using degenerate kernels in the null-field boundary integral equation method abstract: This paper not only derives an analytical solution for steady-state heat conduction problems in exchanger tubes but also can predict the location of numerical instability due to a degenerate scale in the boundary element method or the boundary integral equation method. Four shapes of the exchanger tubes including concentric annulus, eccentric annulus, confocal ellipses, and elliptical tube with a confocal crack are analytically studied by using degenerate kernels of polar, bipolar and elliptical coordinates, respectively. This work extends our prior research on numerical instability and its treatment for steady-state heat conduction problems in exchanger tubes using the dual boundary element method. Analytical solutions of the temperature field and conduction shape factor can be derived. Two main analytical tools, the degenerate kernel for the closed-form fundamental solution and the generalized Fourier expansion for the boundary densities in the null-field boundary integral equation are required. The analytical derivation process can clearly examine the occurring mechanism of numerical instability due to a zero denominator. The effectiveness of regularization techniques to promote the rank-deficiency by one to a full-rank system can be analytically examined in this paper.

Meshless boundary integral quadrature method for calculating the conduction shape factor of exchanger tubes containing slits

title: Meshless boundary integral quadrature method for calculating the conduction shape factor of exchanger tubes containing slits abstract: In this paper, the meshless boundary integral quadrature method (MBIQM) is proposed to determine the conduction shape factor of heat exchanger tubes containing slits. The MBIQM is a meshless method of quadrature form by introducing the adaptive exact solution and Gaussian quadrature. In this way, the singular integral can be technically calculated free of the sense of Cauchy principal value in numerical implementation. When dealing with the boundary value problem containing a slit or so-called degenerate boundary, a rank-deficient influence matrix due to a degenerate boundary may occur. To overcome the rank-deficiency problem, we introduce the dual boundary integral equation (BIE) with the hypersingular BIE to obtain independent equations for collocation points on the slit. A feasible adaptive exact solution is also required for the problem with a degenerate boundary. Since the jump behavior cannot be described by the ordinary form of adaptive exact solution for the corresponding collocation point on the slit, we adopt the harmonic basis function in the elliptical coordinates to construct the new adaptive exact solution. This is the main novelty of this paper. In addition, the numerical instability due to the degenerate scale of an outer boundary is also observed. To avoid the appearance of numerical instability due to a degenerate scale, regularized techniques are employed. Accurate conduction shape factors for any size are obtained by using the proposed approach with regularized techniques.

A two-dimensional hyperbolic spring model for mat foundation in clays subjected to vertical load

The impact of home resources, students' attitudes toward learning, and instructional strategies on science achievement

title: The impact of home resources, students' attitudes toward learning, and instructional strategies on science achievement abstract: Science achievements of individuals play a crucial role when students aim to pursue highly demanded occupations and advanced academic degrees. Enhancing science attainment is crucial in improving the effectiveness of science education. This study investigates the impact of home educational resources, students' attitudes toward learning, instructional practices and strategies, and school factors on science achievement. This investigation utilizes Trends in International Mathematics and Science Study 2019 eighth-grade science data from the United States. The technique of hierarchal linear models is employed to find the effects of the multilevel factors on science achievements. Results of fixed effects show that science achievement is primarily affected by home educational resources, attitude toward learning, and school composition by student background. Of the four attitudinal predictors, students' confidence in science is most correlated to their achievements. Home educational resources, students like learning science, and self-efficacy for computer use predictors, have significant random effects on science achievement. This study finds that ensuring adequate resources and employing appropriate instructional methodologies to reinforce students' motivation in learning are two major priorities in improving science achievement. The limitations of this research and suggestions for future work are also discussed.

An approximate numerical analysis of rafts and piled-rafts foundation

title: An approximate numerical analysis of rafts and piled-rafts foundation abstract: The load distribution and deformation of rafts and piled rafts were investigated by an analytical and numerical studies. Special attention is given to the improved analytical method (MEGA piles) proposed by considering raft-pile flexibility and soil-pile nonlinearity. The response of raft, a three-dimensional, thin-plate substructure that bears on the soil, is analyzed by flat shell approach by combining a membrane element with a Reissner-Mindlin plate element. An improved analytical method is also developed for the design of piled raft. A series of numerical analyses on piled raft were performed for different head connected conditions, asymmetric geometry of raft, raft flexibility, pile diameters. The proposed method has been verified by comparing the results with other numerical methods and a field case study. Through comparative studies, it is found that the proposed method represents a significant improvement in the prediction of piled raft load sharing and settlement behavior.

矩形斷面高層建築扭轉向設計風載重之研究

title: 矩形斷面高層建築扭轉向設計風載重之研究

Steady state heat conduction in exchanger tubes by using the meshfree boundary integral equation method: conduction shape factor and degenerate scale

title: Steady state heat conduction in exchanger tubes by using the meshfree boundary integral equation method: conduction shape factor and degenerate scale abstract: Regarding the steady-state heat conduction problem in exchanger tubes, the meshfree boundary integral equation method is employed to determine the conduction shape factor in this paper. Different from the conventional boundary element method, the present method is free of mesh generation. After using the parametric function to represent the boundary contour and adopting the Gaussian quadrature, only collocating points on the boundary is required to obtain the linear algebraic equations. By introducing the local exact solution, the singular integral in the sense of the Cauchy principal value can be novelly determined. In addition, the boundary layer effect due to the nearly singular integral in the boundary integral equation can be dealt with. Two cases of different boundary conditions are considered. One is the isothermal condition on both the inner and outer surfaces. The other is the isothermal condition on the inner surface and the convection condition on the outer surface. Besides, numerical instability is found and the nonuniqueness solution due to the degenerate scale is examined by calculating the conduction shape factor and the temperature on the outer surface.

Study on the interaction between a screw dislocation and circular holes or rigid inclusions by using the angular basis function in conjunction with bipolar coordinates

title: Study on the interaction between a screw dislocation and circular holes or rigid inclusions by using the angular basis function in conjunction with bipolar coordinates abstract: In this paper, the degenerate kernel in conjunction with the bipolar coordinates is employed to solve the anti-plane problems of interaction between a screw dislocation and circular holes or rigid inclusions. Once the degenerate kernel of the angular basis function (ABF) is provided in terms of the bipolar coordinates, the analytical solution for cases of one or two circular holes and rigid inclusions can be derived. Not only the radial basis function (RBF) but also the ABF is used. First, the observer objectivity of the degenerate kernel in terms of the bipolar coordinates is examined numerically. A special case, one circular hole or rigid inclusion, is considered to demonstrate the validity of the present approach. Finally, the cases containing two circular holes and two circular rigid inclusions were examined. The comparison between available results and ours is well done. Besides, for the solutions of two holes and rigid inclusions, it is interesting to find that the present method provides an analytical solution with a series form of explicitly determined coefficients, while the coefficients provided by the complex variable need to be determined using the recursive formulae.

Analytical solution for potential flow across two circular cylinders using the BIE in conjunction with degenerate kernels of bipolar coordinates

title: Analytical solution for potential flow across two circular cylinders using the BIE in conjunction with degenerate kernels of bipolar coordinates abstract: In this paper, we employ the bipolar degenerate-kernel in the boundary integral equation (BIE) to derive the analytical solution of potential flow across two identical circular cylinders. Analytical results are compared with those in Lebedev et al.. Discussions of the difference between our results and Lebedev’s solution are addressed. Velocity distribution is also plotted. Both analytical solution and velocity plots are given. The key tool is using the degenerate kernel instead of the closed-form fundamental solution. A closed-form fundamental solution is expressed in terms of degenerate kernel by using the bipolar coordinates for a case of two cylinders. The orientation, or so called the angle of attack is considered. The result shows that the degenerate-kernel approach can be an alternative tool for analytically solving some boundary value problems, although the complex variables is always employed. The extension to 3-D problems is promising and straightforward once the degenerate kernel is available since complex variable may have difficulty.

Synergy frontier of multi-factor stock selection model

title: Synergy frontier of multi-factor stock selection model abstract: The classical "efficiency frontier" emphasizes the combination of negatively correlated or low-correlated portfolios to reduce the diversifiable risk of the investment portfolio. While the "synergy frontier" focuses on combining stock selection factors or models with "synergy" to strengthen the ability to increase the return rate of the stock selection model. Therefore, to raise the return, the focus of the multi-factor model is to discover the synergy effects of stock-picking factors. To systematically discover the synergy of stock-picking factors, two profitability factors, ROE and ROC, and two value factors, P/B and P/S were chosen. Then stock picking models that express various styles were systematically generated by means of weighted scoring approach and mixture design. The polynomial regression analysis was employed to build the return and risk models. Then a set of optimal portfolios that offer the highest expected return for a set of various levels of risk can be generated through solving an optimization model. We used the S&P 500 constituent stocks as the stock selection pool. The results showed that (1) There are strong synergy effects of return between the two profitability factors, ROE and ROC, and the value factor, P/B. (2) The relations between factor weights and risk of portfolios are rather linear, which shows that there are no synergy effects of risk between profitability factors and value factors. (3) There is synergy rotation in stock market, and the momentum strategy can overcome the rotation phenomenon and significantly improve the investment performance.

A refined method of multi-target equivalent static wind loads: A bridge case

title: A refined method of multi-target equivalent static wind loads: A bridge case abstract: Evaluation of equivalent static wind load has been one of the most important topics among wind engineering researches. Over the years, methodologies have been developed to evaluate the equivalent static wind load for a single-target structural response (S-ESWL here). However, it is still challenging to apply these methods to large and intricate structures. Evaluation methods based on multiple targets have then been proposed (M-ESWLs here). Unfortunately, These methods often provide erratic load patterns leading to difficulties in initial designs. This research aims to evaluate wind loads for all-target structural responses via only a few numbers of load distributions. The concept of the clustering analysis is converged with the M-ESWL methods. Similar structural dynamic responses are categorized into the same cluster. By the single value decomposition technique, the M-ESWLs are generated based on fewer load vectors. An example of a pedestrian bridge containing a curved steel arch with significant coupling features was given. Results showed that the approach proposed in this research provided fair consistencies of 528 target displacement responses with only eight load patterns. Furthermore, the load patterns showed more realistic distributions in values than the load pattern produced by the method based on the Universal Equivalent Static Wind Load.

Numerical and Experimental Studies on the Aerodynamics of NACA64 and DU40 Airfoils at Low Reynolds Numbers

title: Numerical and Experimental Studies on the Aerodynamics of NACA64 and DU40 Airfoils at Low Reynolds Numbers abstract: The aerodynamics of airfoils can be seen in a wide range of applications. To obtain the aerodynamic loads, geometrically-scaled airfoil sections are tested in wind tunnels. However, due to the limited space of the wind tunnel, the mismatch of Reynolds numbers may lead to different aerodynamic loads. Previous works showed that decreased lifts and increased drag coefficients are associated with lower Reynolds numbers, which are accompanied by the changes in ambient flow, such as increased sizes of the separation bubbles and wake vortices. Although insightful, few direct connections between loads, pressures, and ambient flow were presented, leaving a critical knowledge gap for aerodynamic modifications to improve the aerodynamic performances at low Reynolds numbers. To bridge this gap, this work utilizes numerical simulations and wind tunnel experiments to study the aerodynamics of a thin airfoil (NACA64) and a thick airfoil (DU40), at two chord Reynolds numbers, i.e., 4000 and 60,000. The two-dimensional (2D) vortex particle method (VPM) with varying-sized particles is used to simulate the unsteady flow and compared to the steady-state simulations by XFOIL. As the Reynolds number increases, it reveals that the higher lift coefficients are associated with the increased upstream suction and positive pressures on the upper and lower surfaces of the airfoils, respectively. These changes are explained by the increased and decreased normalized wind speeds on the upper and lower surfaces of the airfoils, respectively. Stronger pressure recoveries observed downstream of the reattachment points are the main cause of drag reductions at higher Reynolds numbers. The smaller and more irregular vortices in the roll-up shear layers and wakes observed at the higher Reynolds number are similar to the previous experimental findings, which are shown in this work to make the force fluctuations more irregular at higher frequencies. Possibly due to missing 3D effects, the results obtained from the 2D VPM are observed to ‘overestimate’ the effects of increasing the Reynolds number at ReC = 60,000. Furthermore, both VPM and XFOIL are found to work best in explaining the physics at low angles of attacks, i.e., −10°≤α≤10° , which are similar to the previous numerical works utilizing 2D methods.

Identification of Multimodal Dynamic Characteristics of a Decurrent Tree with Application to a Model-Scale Wind Tunnel Study

title: Identification of Multimodal Dynamic Characteristics of a Decurrent Tree with Application to a Model-Scale Wind Tunnel Study abstract: Wind tunnel tests of scaled model trees provide an effective approach for understanding fluctuating wind loading and wind-induced response of trees. For decurrent trees, vague multimodal dynamic characteristics and ineffective estimation of leaf mass are two of the main obstacles to developing aeroelastic models. In this study, multimodal dynamic characteristics of the decurrent tree are identified by field measurements and finite element models (FEM). It was found that the number of branches swaying in phase determines the magnitude of effective mass fraction of branch modes. The frequencies of branch modes with larger effective mass fraction were considered as a reference for an aeroelastic model. In addition, an approach to estimate leaf mass without destruction was developed by comparing trunk frequency between field measurements and FEM. Based on these characteristics of the prototype, the scaled, aeroelastic model was constructed and assessed. It was found that the mismatch of leaf stiffness between the model and the prototype leads to mismatch of leaf streamlining and damping between them. The Vogel exponent associated with leaf streamlining provides a possible way to ensure consistency of leaf stiffness between the model and prototype.

Settlements and Subgrade Reactions of Surface Raft Foundations Subjected to Vertically Uniform Load

title: Settlements and Subgrade Reactions of Surface Raft Foundations Subjected to Vertically Uniform Load abstract: The settlements and corresponding soil reactions of a surface raft foundation subjected to vertically uniform load at the sites of granular or cohesive soils have been qualitatively introduced to engineers in the past. This study intends to verify the foundation load-response mechanism using three-dimensional finite-element analyses. The Mohr–Coulomb soil model was used to simulate the nonlinear effects of the granular and cohesive soils. The coefficients of subgrade reactions of the soil were back-calculated and compared to those obtained from the rigid foundation model. For all the square surface rafts studied, non-uniform settlements with the largest value at the center can be found. For the smallest rafts located in clay, the soil reactions were found to be rather consistent. For larger rafts in clay, the soil reactions would be changed according to the soil stiffness and raft dimensions. For surface rafts in sand, the effects of soil stiffness on soil reactions appeared to be insignificant. The soil reactions were generally higher at the center and varied with raft dimensions. For the smallest raft in sand, large soil reactions can be found at the edge. The coefficients of subgrade reactions were found to be more consistent with the smallest values occurring at the center. The results of this study indicate that the load-response mechanism of the raft foundation is rather complicated. Such load-response mechanisms are strongly affected by the relative rigidity of the foundation depending on soil stiffness and foundation dimensions.

The Impacts of Work Environment and Teacher Attributes on Teacher Job Satisfaction

title: The Impacts of Work Environment and Teacher Attributes on Teacher Job Satisfaction

Soft logic delay analysis technique

title: Soft logic delay analysis technique abstract: Current delay analysis techniques assume that there is only one logical sequence of activities in a project. However, in a real construction project, the relationship of activities can be demonstrated by both fixed and soft logic. Fixed logic requires activities to be executed in a specific order, whereas soft logic allows activities to be executed in various orders. Due to the existence of soft logic and the contractor's obligation to mitigate delays, it is necessary to update the logic to calculate Extension of Time (EOT). However, when soft logic is present in a schedule, manual updates are time-consuming and error-prone. To facilitate soft logic updates, several models have been proposed, however, these methods only update soft-logics within activities of the same work item, rather than project-wide. To overcome the limitations of the previous research, this paper proposes an algorithm to update schedules according to delay events project-wise. Furthermore, the proposed model has been verified using practical cases, demonstrating a successful way of applying this model to update schedules based on delay events, allowing EOT to be calculated automatically as well as more accurately and reasonably.

以柔性加勁工法減緩逆斷層錯動引致之地表變形

title: 以柔性加勁工法減緩逆斷層錯動引致之地表變形

Vector Form Intrinsic Finite Element Method for Stochastic Analysis of Train – Track – Bridge Coupling System

title: Vector Form Intrinsic Finite Element Method for Stochastic Analysis of Train – Track – Bridge Coupling System abstract: In this paper, a train–track–bridge (TTB) interaction model that can account for coach-coupler effect is presented for stochastic dynamic analysis of a train traveling over a bridge. Based on the vector form intrinsic finite element (VFIFE) method, both the bridge and non-ballasted track are discretized into a set of mass particles connected by massless beam elements, in which the fasteners that fixed the tracks on the bridge deck are modeled as a series of linear spring-dashpot units. The multi-body train car is regarded as seven mass particles (1 for car body, 2 for bogies and 4 for wheelsets) connected by parallel spring-dashpot units. Considering the random nature of rail irregularities, the Karhunen–Loéve expansion (KLE) method is used to simulate the vertical profile of the tracks. To calculate the mean and standard deviation of the stochastic response of the TTB system, the point estimated method (PEM) based on the Gaussian integration and dimension reduction method is adopted. The proposed VFIFE–TTB interaction model is then applied to stochastic resonance analyses of a train moving on a bridge. It is shown that the present VFIFE–TTB model is able to analyze the dynamic interaction of the TTB system simply and efficiently. The influence of rail irregularity-induced stochastic vibration on the train and bridge would become significant once the resonant vibration takes place on the TTB system.

A method to estimate peak pressures on low-rise building models based on quasi-steady theory and partial turbulence analysis

title: A method to estimate peak pressures on low-rise building models based on quasi-steady theory and partial turbulence analysis abstract: A new method for estimating peak area-averaged pressure coefficients on the roof of a low-rise building model is developed. The method relies on the well-known quasi-steady vector model to account for the large-scale, low-frequency fluctuations of the upstream wind. The novel approach is to account for small-scale and body-generated turbulence effects using a stochastic model. Wind tunnel data for a 1/50-scale low-rise building model for six different upstream turbulence conditions are used for the analysis. The fluctuating pressure component induced by the small-scale and body-generated turbulence is obtained by subtracting the quasi-static pressure component from the original pressure signal. It is observed that the small-scale pressure component is highly dependent on turbulence level of the upstream flow, such that normalization by the small-scale components of the upstream turbulence kinetic energy leads to a self-similar distribution. A Monte Carlo simulation was used to combine the small-scale and quasi-steady pressure components. The new model provides good predictions of peak area-averaged pressure coefficients that cannot be captured by the quasi-steady approach.

Assessments of Soil Parameter Reduction Coefficients from One-Dimensional Ground Response Analyses

title: Assessments of Soil Parameter Reduction Coefficients from One-Dimensional Ground Response Analyses abstract: Soil parameter reduction coefficient (DE) has been suggested by Architecture Institute of Japan (AIJ) and Japan Road Association (JRA) for over twenty years. The reduction coefficient denoted as DE was used to reduce stiffness and/or strength parameters of the soil due to liquefaction caused by earthquakes. This study discusses the observations based on soil parameter reduction coefficients calculated from one-dimensional dynamic responses on artificial ground sites under horizontal earthquakes. A lumped mass model of horizontal sand layers is used. Soil liquefaction is modeled using the UBCSAND model. The factor of safety against liquefaction and the cyclic strength ratio for soils at various depths are calculated from the mechanical analyses to find the reduction factors based on the suggestions from JRA and AIJ. In addition, the ratio between the degraded shear modulus and the initial shear modulus of the soils are computed and compared to the reduction coefficients found varying the influence factors.

Length Influences on Lateral Performance of Barrette from Three-Dimensional Finite Element Analysis

title: Length Influences on Lateral Performance of Barrette from Three-Dimensional Finite Element Analysis abstract: The performance of a single barrette subjected to lateral load applied at its top is presented in this paper using three-dimensional finite element analyses based on Midas GTS program. Nonlinear behaviors of the barrettes buried in clayey and sandy soils were monitored using Mohr-Coulomb soil model. Performances of the barrettes with lateral loads applied in both longitudinal and transverse directions were examined. Displacements of the barrettes affected by stiffness and strength of the soils were obtained and normalized with the nominal length of the barrette. The criteria for long and rigid barrettes with loads in different directions were suggested. For the barrettes with loads in the transverse direction, the conventional analytical solution suggested by Chang for a single pile was found applicable to the predictions. In such case, the equivalent diameter calculated from moment of inertia of the barrette was found more adequate to be used in the analytical solution. Results of this study can help the engineers to understand more about the barrette performance under lateral loads.