Economic Design Research Articles

Vehicle Collision Load Design Demands for Deck Overhangs with Parapet Railings

The majority of bridge rails used in the U.S.A. and Canada are solid concrete parapets. However, the design procedure included in the AASHTO LRFD Bridge Design Specifications (BDS) for deck overhangs supporting parapets has not been modified for nearly 50 years. The specifications currently recommend that the deck overhang moment demand is taken as the cantilever bending strength of the parapet at its base. This recommendation results in uneconomical deck designs if the parapet is overdesigned. In this research effort, which was performed under National Cooperative Highway Research Program Project 12-119, the distribution of vehicle impact loads through the parapet and overhang was characterized, new equations were proposed to calculate overhang design demands, and the effect of deck understrength on parapet capacity was quantified. To develop updated design guidance, physical testing of instrumented specimens was performed, and validated LS-DYNA models were used to evaluate a variety of in-service railing and overhang designs. Results indicated that deck moments from lateral vehicle impact loads can be reliably estimated by assuming they distribute at 45 degrees with downward travel through the parapet and at 60 degrees with inward travel through the overhang. These angles are used to calculate effective lengths at critical sections, and overhang design moments are calculated by dividing the total applied moment over these lengths. Distribution of tensile loads was found to be minimal. The overhang design guidance developed in this project, which is currently under review for adoption into the BDS, routinely results in more economical deck designs than the existing method.

Optimization-based innovative approach for economical design of reinforced concrete isolated footings

Optimization-based innovative approach for economical design of reinforced concrete isolated footings

Cross-sectional optimisation of I-shape pultruded FRP beams using search-adaptive micro-population genetic algorithm

Despite the growing utilisation of pultruded fibre-reinforced polymers (PFRP) profiles in infrastructure applications, there is still a scarcity of design tools with a feasible computational cost. Such shortage deprives these profiles of competing with economic cost and optimised performance against other construction materials. This research investigated the numerical optimisation of cross-sectional geometry and anisotropy ratio of I-shape PFRP beams for the design against local buckling of flange under bending and web under transverse compression. A new search-adaptive micro-population genetic algorithm (SA-µP GA) tool was proposed to achieve accurate results with low computational cost. This tool was verified and compared with other GA codes from the literature. The artificial neural networks (ANNs) machine learning tool was used to maximise the use of data and generate practical and economic design charts considering the varying interactions between the design parameters. This optimisation approach represents an efficient design tool to achieve the design requirements of stability, strength, and serviceability (stiffness) limits with minimum cost and optimal structural performance. The optimisation approach was addressed using four case studies from the literature.

Examiner and Judge Designs in Economics: A Practitioner's Guide

Examiner and Judge Designs in Economics: A Practitioner's Guide

Izgradnja ceste primjenom drvnog pepela

This paper describes the specifics of constructing a test section of an internal road where wood ash was used to improve the bearing capacity of the subgrade and to construct the base layer of the pavement structure. Laboratory testing and field control testing were conducted during the construction. The results showed that the increase in the bearing capacity of the subgrade by applying stabilization with wood ash ranges from 155 to 235 % compared to the natural clay subgrade. Due to the binding properties of wood ash, the bearing capacity of the subgrade continues to increase even after construction, with an observed increase of 31 to 39 % in bearing capacity within 14 days of construction. The base layer made of wood ash of different fractions achieved compressive modulus Ms = 60 to 80 MN/m², thus meeting the bearing capacity criteria. The experiences from the test section confirm the potential of wood ash for use in improving subgrade bearing capacity and in the construction of the base layer of pavement structures. This could encourage more rational and economical design and construction of pavement structures, especially in areas with large amounts of waste ash from wood biomass, such as the region of Slavonia.

Characterising geomaterial shakedown and related deformation accumulation from cyclic triaxial tests

Permanent deformation accumulation in soils and unbound granular materials under repetitive loading leads to surface rutting in roads and deterioration of track geometry in railways, eventually requiring costly and disruptive maintenance. Cyclic or repeated load triaxial tests are a convenient test method to characterise the permanent deformation behaviour of different soils under high numbers of load repetitions and a large volume of data is available. Existing empirical functions either take no account of shakedown, leading to an over-prediction of deformations at a high number of load cycles, or those that do take account of shakedown contain a high number of regression parameters that make them difficult to use. A simple empirical function with only one input parameter is proposed to characterise the accumulation of permanent axial strain in cyclic triaxial tests on a wide range of geomaterials undergoing shakedown deformations. It is shown to give predictions of a similar accuracy to existing functions at low numbers of load cycles and increased accuracy at high numbers of load cycles. It is shown to be applicable to soils ranging from a high plasticity clay to a rail ballast, across a range of stress states, stress history and strain levels provided that ratcheting deformations do not occur. The single input parameter has a physical meaning and is related to the permanent deformation required to reach the shakedown condition. Since the proposed function predicts the slowing rate of deformation accumulation towards shakedown not covered by the commonly-used existing functions, it could lead to more economical designs of applications involving high numbers of load repetitions. Its broad application to both coarse granular materials and fine-grained soils should streamline the design of applications involving layers of both these material types without the need to change empirical function.

Performance-based evaluation on egress safety of disabled welfare facilities

ABSTRACT With the increasing number of fire incidents, efforts are being made to quantitatively evaluate the egress safety of buildings. In particular, studies that reflect the behavioural characteristics of occupants when evaluating egress safety are being conducted. However, the research on the performance design and safety evaluation of facilities where individuals vulnerable to disasters (i.e. those who have difficulty evacuating in the event of a fire) reside remains insufficient. In this study, fire evacuating simulations were performed on welfare facilities for disabled individuals with mobility issues, and the egress safety was evaluated. The fire simulations were performed using the capacity of the smoke exhaust system as a variable. Meanwhile, the variations in temperature and toxic gases according to fire duration were analyzed to calculate the available safe egress time (ASET). The egress simulations were performed using the egress delay time and the number of egress guides as variables. Then, the required safe egress time (REST) was calculated. The results show that increasing smoke exhaust system delays the attainment of tenability limits, improving ASET. Egress simulations revealed an optimal number of egress guides. Based on these findings, general criteria have been developed to assess egress safety, considering the building floor area, smoke exhaust capacity, and occupant numbers. These criteria can be applied to ensure efficient and economical safety designs for typical welfare facilities for the disabled. HIGHLIGHTS Egress safety of disabled welfare facilities was evaluated by FDS. ASET was derived based on smoke exhaust capacity and fire duration. RSET was derived by considering evacuation delays and instructions. Findings support efficient, cost-effective safety design for disabled care facilities.

Multi-Objective Optimization of the Layout of Tall Building Sites in Dense Urban Configurations for Improved Sustainability Outcomes

Multi-objective evolutionary algorithms have long been used by architects to find objective solutions to complex building problems involving trade-offs implicit in sustainable building design. At a larger scale, urban designers have created a variety of tools to improve sustainability in urban-and-larger scale design. However, to date, fewer studies have focused on improving sustainability outcomes at the “in between” scale of the neighborhood and urban site. Existing scholarship on optimization at this scale has tended to take a narrow view of sustainability. We seek to expand the implementation of multi-objective evolutionary algorithms to this sometimes overlooked scale while taking a broad view of sustainability which includes social, environmental, and economic design factors. In doing so, we argue this optimization method is uniquely well suited to help designers balance the sometimes competing demands of multiple axes of sustainability which are applicable to design at this larger-than-building scale. In demonstrating the application of such an algorithm to a hypothetical problem in Chicago, we find the method offers a promising way of narrowing potential design solutions. Finally, we discuss the suitability of the solutions generated, the virtues and shortcomings of the method, and offer areas for future study.

From features to benefits: a data-driven approach for the economic design of adaptive quality control

The current economic design of control charts assumes specific quality distributions, limits parameter choices, and over-relies on historical samples, hindering companies from determining the most economical parameters accurately. Leveraging industrial big data, we propose a data-driven, mixed-integer linear programming model for the economic design of adaptive control charts. Control limits are dynamically designed as a function of features to minimise quality costs. Considering the trade-off between false alarms and penalty costs, we develop three models: a basic model incorporating big data, a model with cost-penalised features, and a model that uses regularisation to manage overfitting. We simulate the model using new performance measures. Our findings demonstrate the economic value of adaptive control limits strategies incorporating feature data compared to benchmarks. We expanded the model to an endogenous sample size and sampling interval framework, further demonstrating the superiority of our approach. We undertook a case study using real-world data from a casting company and revealed that employing our approach culminates in a 24.6% reduction in costs relative to the company's existing quality control protocols. Our approach enables manufacturers to make strategic decisions about quality control by operationalising big data, thereby proving advantageous in reducing quality costs.

Effect of Tray Geometry on Multitray Stepped Solar Still Performance: An Experimental Study

ABSTRACTThe multitray solar still (MTSS) is one of the most efficient and economical designs compared with other solar still systems. MTSS has lower heat loss and a large evaporation area, and its basin is more exposed to solar radiation. Nevertheless, optimizing the tray's geometry is essential to improve the still's thermal behavior and productivity. The primary goal of this study is to examine the effect of the tray's geometry on the MTSS performance under outdoor experiments. A comparative analysis was conducted between the triangular‐trays solar still (TTSS), the rectangular‐trays solar still (RTSS), and the single‐slope conventional solar still (CSS) in winter and summer weather conditions. Results show that integrating a multitray evaporator improves the daily yield compared with the CSS and that the thermal performance of the modified solar still depends mainly on the weather conditions. The comparison shows that the triangular trays are more effective than the rectangular ones. The daily productivity of TTSS exceeds that of RTSS by 10% in winter and 24.24% in summer. Moreover, the daily thermal efficiencies of CSS, RTSS, and TTSS are maximum in summer conditions by about 28.1%, 41.2%, and 44.15%, respectively.

Study on economic design and construction program of steel-hybrid combined girder bridge

In order to make full use of steel tensile and concrete compressive properties, combined beam cross-section stress-strain distribution characteristics and cross-section characteristics and loading procedures are closely related. At present, the cross-section form of I-beam combined with concrete panel is widely used, and the strength of the upper flange of the steel beam of the supported combined beam and the strength of the concrete panel of the unsupported combined beam have not been fully utilized. Through the theoretical analysis of different loading methods of combined beam strain stress distribution, so as to optimize the cross-section form, the proposed supported combined beam using the lower inverted T-shaped cross-section combined with the form of concrete panels, in the given actual engineering cases can obtain a higher elastic ultimate bearing capacity and can save 9.5% of the amount of steel. The unsupported loading method of I-beam combination beams can use lower grade concrete for better economy. Making full use of the neutral axis position change to design the combined beam cross-section is operable, inverted T-shaped steel beams combined with concrete panel combined beams is a way to save steel and reduce the construction of welded joints, with significant economic benefits.

Economic Design of Quality control by Using Triangular Fuzzy Number with Alpha Cut

Manufacturers today prioritize increasing output quality while reducing per-unit costs to remain competitive. Statistical Process Control (SPC) is a useful tool for boosting quality and output. However, decision-makers in industries face difficulties in cost and quality control due to uncertainty in data. Fuzziness can be applied to uncertain data to manage the economic design of a control chart, allowing for better control over the control chart's economic design. This study seeks to enhance the economic design of X control charts by using fuzzy set theory, specifically utilizing triangular fuzzy numbers for cost parameters and the signed distance approach for defuzzification. The objective is to enhance the adaptability of these charts in unpredictable situations. The proposed model enables the incorporation of cost parameters inside a fuzzy framework, with the objective of minimizing the control chart while adhering to the permissible limit. The applicability and improved accuracy of the model in optimizing control chart parameters for a glass bottle production process are exemplified by an effective illustration. This study highlights the need of integrating fuzzy logic into SPC. It suggests a technique that improves the cost-effectiveness and operational effectiveness of control charts in situations when data is uncertain and imprecise. . KEYWORDS :Statistical quality control, Economic quality control, Triangular fuzzy number, Signed-distance, Alpha cut.

FACTORS INFLUENCING INDIVIDUAL CONSUMERS’ INTENTIONS TO PURCHASE ELECTRIC VEHICLES IN URBAN HANOI

This study aims to identify the factors influencing the intention to purchase electric vehicles for personal use among residents in major urban areas in Vietnam, specifically in Hanoi. This research was conducted using a non-probability sampling method to recruit 360 participants currently residing, studying, or working in the city of Hanoi. Statistical analysis was employed to process the collected data. The results reveal four groups of factors that have an impact on the intention to purchase electric vehicles among urban residents in Hanoi: (1) attitude (economic benefits, environment, safety, convenience, and design), (2) perceived behavioral control, (3) attractiveness of alternative modes of transportation, and (4) subjective norms. Based on the findings, the authors propose several policy implications to promote the development and use of electric vehicles in urban Hanoi. These may include encouraging the use of electric vehicles from economic, environmental, and safety perspectives, creating financial support programs or tax incentives for electric vehicle buyers, and improving public electric charging infrastructure to make electric vehicle usage more convenient.

AISC360-22 design equations for high-strength concrete-filled tubes: From rectangular to circular sections

The current AISC Specification lacks clear guidance on the design of circular concrete-filled tube (CCFT) members, while updates to material strength restrictions and the P-M interaction design curve apply exclusively to rectangular shapes. This research is a response to the growing call within the engineering community to update the AISC 360–22 design guidelines for CCFTs. A deterministic and probabilistic approach is presented for assessing the applicability of unifying current AISC 360–22 P-M interaction design equations for use in circular-filled tubes. This assessment is informed by the most up-to-date experimental test results comprising 508 eccentric axially loaded CCFTs with different material strength combinations. Reliability analysis using Monti Carlo simulation demonstrates that the authors' proposed P-M interaction design equations in Appendix II of the AISC 360–22, along with the proposed equation for column, and beam maintain a consistent level of accuracy across different material strengths of circular shapes. An increased safety factor of ϕc = 0.85 for columns and ϕb = 0.9 for beams is recommended for a more economical design, aligning with AISC 360–22's requirement for achieving a minimum reliability index of 2.6 under commonly used load combinations. The research findings present a compelling proposal for inclusion in design codes, offering practical tools for engineers to enhance structural design and safety optimization.

Design Process, Evaluation, and Sensitivity Analysis of an Activated Carbon Production Plant from Single-use Plastic Waste at the National University of Engineering

Objective: The objective of this study is to investigate the design process, economic evaluation, and sensitivity analysis for the construction of an activated carbon production plant from single-use plastic waste at the National University of Engineering. This project aims to transform plastic waste into a high-value-added product, thereby contributing to sustainability and aligning with circular economy principles. Theoretical Framework: The theoretical framework covers concepts related to the circular economy and sustainable waste management, emphasizing the need to reduce environmental impact through innovative alternatives such as recycling PET into activated carbon. Previous studies on pyrolysis and thermal or chemical activation of plastics for conversion into high-value materials are cited, establishing a solid foundation to contextualize the activated carbon production process. Method: The methodology adopted for this research includes a technical and economic study design based on the assessment of processes and equipment required for activated carbon production. An experimental approach is proposed, wherein plastic waste is collected, shredded, washed, dried, carbonized, activated, and finally packaged. Data collection involved detailed calculations of investment, energy consumption, and mass and energy balances for each stage of the production process. Results and Discussion: The results revealed that the project is economically viable, with a Net Present Value (NPV) of 59,733 USD and an Internal Rate of Return (IRR) of 13%. In the discussion, the project’s profitability is contextualized through a sensitivity analysis evaluating different scenarios of exchange rate and sale price. This analysis confirms that, in optimistic scenarios, the IRR can reach up to 341%, reducing the payback period to less than a year. Research Implications: The practical implications of this research include the potential to implement a circular economy model in educational institutions, promoting sustainability and efficient waste management. Theoretically, the study contributes to the field of plastic waste valorization through its transformation into activated carbon, which could positively impact sectors such as environmental management and industrial recycling. Originality/Value: This study contributes to the literature by presenting an innovative approach for plastic waste valorization into activated carbon within an educational institution, using pyrolysis and activation processes in a circular economy context. The relevance of this research lies in its practical applicability in academic settings and its potential impact on reducing plastic waste.

Economic design of a self-healing policy with limited agents

Self-healing has been increasingly integrated into systems to enhance their reliability. Many popular intrinsic self-healing policies are not cost-effective because their self-healing actions are not always performed at the right time. This paper investigates the economic design of a self-healing policy with limited agents for an intelligent system that executes a mission of finite length. Several healing agents are embedded into the system before the mission. The system performs self-detection at equidistant epochs to reveal deterioration levels. The deterioration can be randomly healed by releasing healing agents, and the healing effect depends on the number of agents released. At each inspection epoch, a decision is made on how many healing agents to be released. The objective is to jointly determine the capacity of agents and the self-healing policy to minimize the expected total cost over the mission length. The optimization problem is formulated in the stochastic dynamic programming framework. A backward induction algorithm is developed to find the optimal solution. A numerical example is provided to illustrate the effectiveness of the proposed approach. The comparison with a control-limit policy confirms the outstanding performance of the proposed policy.

Designing postcapitalist finance in Protocols for Postcapitalist Expression

Abstract Protocols for Postcapitalist Expression, the Economic Space Agency’s latest experiment in radical economic design, explores the possibility of designing a digitally native economy that is geared towards care, the arts, and the environment, and which not only refuses to give up on the financial frontiers of contemporary capitalism, but actively seeks to marshal them towards innovative ends. The architecture of a novel economic space comes into view through a set of protocols, which integrate economic information within a social value framework. This ‘Economic Space Protocol’ involves crafting a new grammar for economic information production processes that have traditionally been tied to competitive market behavior. This essay interrogates the place of finance in the book, emphasizing price discovery’s generativity with regards to information. What is necessary in the imagination of any postcapitalist future are radical design initiatives that contend with both the necessity and the limits of the price discovery process.

Improving the potential of fifth-generation district heating and cooling networks through robust design and operational optimization under future energy market and demand uncertainties

Network investments and projected energy prices greatly impact the financial viability and environmental impact of fifth-generation district heating and cooling (5GDHC) networks. Compared to the previous generation, the upfront investment costs in 5GDHC networks are relatively high due to the decentralized energy demand and supply of the participating prosumers. The transition to 5GDHC is also hindered by uncertain energy markets and the fluctuating energy demands of the prosumers. It makes investors hesitant to commit, even for promising business cases. In this work, a framework is presented to assess the economic and environmental performance of a 5GDHC business case, based on a multi-objective robust optimization algorithm (MO-RDO), to identify the optimal trade-offs between environmental and economic designs. The proposed methodology consists of four steps. In the first two steps, a specific business case is modeled, and techno-economic and environmental performances are analyzed against uncertain energy markets. In the third step, the techno-economic and environmental indicator responses are used to develop a data-driven machine-learning model. This model offers better computational efficiency than a high-fidelity nonlinear model and assesses the most influential parameters driving economic and environmental performance via a global sensitivity analysis. This aids in refining the multi-objective robust design optimization (MO-RDO) framework by pinpointing key design variables and objectives amid data uncertainties. Additionally, the formulated MO-RDO provides a mix of environmentally and economically optimal network designs and operational parameters and highlights the trade-offs between them. The designs and trade-offs are evaluated using financial metrics like net present value (NPV), return on investment, and discounted payback period. These metrics are calculated over the project life, considering the initial investment and net savings. For the considered case, the environmental design has a 10% higher investment cost compared to the economically optimal solution but reduces total emissions (TE) by 13% and improves operational cost savings, which is crucial for better financial indicators. The proposed framework aligns with the EU transition plan to incorporate waste energy sources and decarbonization paths, estimating only a 3% increase in NPV as a risk for the environmentally optimal solution on a financial scale.

The multi-objective economic statistical design of the p-chart: NSGA II approach

A control chart is a crucially important tool in statistical process control that is essentially used to differentiate between assignable and chance causes of variation. With the advent of Six Sigma in the parlance of quality management, the control chart assumes more significance to hold the gain in the control phase after attaining process improvement in the improve phase. The sample size, sampling interval, and control limits’ multiplier are three important parameters required to design an effective as well as efficient control chart. Many approaches like economic design, statistical design, and economic statistical design of control charts have been studied by several researchers. All these approaches consider a single objective function. In this paper, we have proposed a multi-objective design of the p-chart, where we are minimizing both out-of-control Average Run Length ( ARL δ ) and the expected cost per cycle ( C E ). Non-dominated Sorting Genetic Algorithm II (NSGA II) is used to solve the proposed multi-objective model. The proposed approach is demonstrated with the help of two numerical examples and the corresponding results are found to be quite encouraging for minimizing both objectives in comparison to another pertinent model given in the literature. Sensitivity analysis has been carried out to give credence to the worth of the proposed approach.

Structural dynamic characteristics of vertical axis wind and tidal current turbines

Vertical axis turbines have received great attention in both offshore wind and tidal current energy communities considering their advantages of economic design and unidirectional operation. However, their commercialization process is rather slow compared with the development of horizontal axis turbines due to technical challenges resulting from higher loads from unsteady aero/hydrodynamic forces, centrifugal forces and gravity of the structures. These are mainly because, while the inherent unsteady tangential pulls and fatigue loads intensify the structural vibration, aggravating structural safety and fatigue life, the relationship between the geometric parameters and the structural responses of blades remains unclear. Therefore, in order to clarify this issue, in this study, we focus on the modal and transient analysis of vertical axis turbines using multi-body dynamics, geometrically exact beam theory and detached eddy simulation. We find that the natural frequency of the rotor is directly related to the ratio of blade length and arm length. The effect of arms cannot be ignored in the structural analysis of the turbine. Moreover, an increase of blade length intensifies the deformation and vibration of the turbine’s structure, making the turbine more prone to fatigue failure. This article is expected to extend the existing knowledge of wind and tidal current turbines and provide a reference for choosing proper design parameters and developing suitable-capacity vertical axis turbines.