다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

In this paper recent developments in the estimation of frontier functions and the measurement of efficiency are surveyed, and the potential applicability of these methods in agricultural economics is discussed. Frontier production, cost and profit functions are discussed, along with the construction of technical, allocative, scale and overall efficiency measures relative to these estimated frontiers. The two primary methods of frontier estimation, econometric and linear programming, are compared. A survey of recent applications of frontier methods in agriculture is also provided. (This abstract was borrowed from another version of this item.)

Recent Developments in Frontier Modelling and Efficiency Measurement

Review of digital twin about concepts, technologies, and industrial applications

The concept of a digital twin has been used in some industries where an accurate digital model of the equipment can be used for predictive maintenance. The use of a digital twin for performance is critical, and for capital-intensive equipment such as jet engines it proved to be successful in terms of cost savings and reliability improvements. In this paper, we aim to study the expansion of the digital twin in including building life cycle management and explore the benefits and shortcomings of such implementation. In four rounds of experimentation, more than 25,000 sensor reading instances were collected, analyzed, and utilized to create and test a limited digital twin of an office building facade element. This is performed to point out the method of implementation, highlight the benefits gained from digital twin, and to uncover some of the technical shortcomings of the current Internet of Things systems for this purpose.

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Digital Twin: Vision, Benefits, Boundaries, and Creation for Buildings

Digital Twin for maintenance: A literature review

Digital twin aided sustainability-based lifecycle management for railway turnout systems

With buildings around the world accounting for nearly one-third of global energy demand and the availability of fossil fuels constantly on the decline, there is a need to ensure that this energy demand is efficiently and effectively managed using renewable energy now more than ever. Most research and case studies have focused on energy efficiency of ‘new’ buildings. In this study, both technical and financial viability of Net Zero Energy Buildings (NZEB) for ‘existing’ buildings will be highlighted. A rigorous review of open literatures concerning seven principal areas that in themselves define the concept of NZEB building is carried out. In practice, a suitable option of the NZEB solutions is needed for the evaluation and improvement for a specific geographical area. The evaluation and improvement has been carried out using a novel hierarchy-flow chart coupled with a Building Information Model (BIM). This BIM or digital twin is then used to thoroughly visualize each option, promote collaboration among stakeholders, and accurately estimate associated costs and associated technical issues encountered with producing an NZEB in a pre-determined location. This paper also provides a future model for NZEB applications in existing buildings, which applies renewable technologies to the building by aiming to identify ultimate benefit of the building especially in terms of effectiveness and efficiency in energy consumption. It is revealed that the digital twin is proven to be feasible for all renewable technologies applied on the NZEB buildings. Based on the case study in the UK, it can be affirmed that the suitable NZEB solution for an existing building can achieve the 23 year return period.

/pdf/a-digital-twin-evaluation-of-net-zero-energy-building-for-4me8sjvnpw.pdf

A Digital-Twin Evaluation of Net Zero Energy Building for Existing Buildings

The railway station is a primary asset of public transport systems and plays a crucial role in urban modernization. Most existing railway stations in the UK is historic and have been operated for many years. Maintenance and reconstruction are common concerns in the public railway industry, and clusters of information pertaining to this maintenance must be managed appropriately for effective outcome. Digital twin or BIM (Building information modeling) is a term frequently employed in the construction industry nowadays, because of its ability to provide wider and faster access to comprehensible and integrated information. A digital twin or a BIM is not only a tool, but also a process that can help to make changes in construction industry, which has remained unchanged for hundreds of years. This paper discusses a specific BIM application within the context of railway station buildings using a Revit-based simulation of construction work for King’s Cross station in London. The paper highlights the adoption and transformation of 3D model of the King’s Cross station building into a 6D building information model. The 6D model contains a time and cost schedule with carbon emissions calculation, and renovation assumptions using Revit. The outcome of this study can provide construction participants with reasonable guidance of BIM adoption on railway station projects that can be used for planning, designing and operating an economic and environmental efficient construction project.

/pdf/digital-twin-for-sustainability-evaluation-of-railway-an8smbsyyc.pdf

Digital twin for sustainability evaluation of railway station buildings

There is no doubt that the use of waste rubber in concrete applications is a genius alternative because Styrene is the main component of rubber, which has a strong toxicity and is harmful to humans. Therefore, it will significantly reduce impacts on the environment when waste rubber can be recycled for genuine uses. In this paper, the dynamic properties of high-strength rubberised concrete have been investigated by carrying out various experiments to retain the compressive strength, tensile strength, flexural strength, electrical resistivity, and damping characteristics by replacing fine aggregates with micro-scale crumb rubber. Over 20 variations of concrete mixes have been performed. The experimental results confirm that a decrease in the compressive strength can be expected when the rubber content is increased. The new findings demonstrate that the high-strength concrete can be enhanced by optimal rubber particles in order to improve splitting tensile and flexural strengths, damping properties, and electrical resistivity. It is therefore recommended to consider the use of rubberised concrete (up to 10 wt. % crumb rubber) in designing railway sleepers as this will improve the service life of railway track systems and reduce wastes to the environment.

https://www.mdpi.com/1996-1944/11/7/1169/pdf

Enhancement of Dynamic Damping in Eco-Friendly Railway Concrete Sleepers Using Waste-Tyre Crumb Rubber

In recent years, railway systems have played a significant role in transportation systems due to the demand increase in conveying both cargo and passengers. Due to the harsh environments and severe loading conditions, caused by the traffic growth, heavier axles and vehicles and increase in speed, railway tracks are at risk of degradation and failure. Condition monitoring has been widely used to support the health assessment of civil engineering structures and infrastructures. In this context, it was adopted as a powerful tool for an objective assessment of the railway track behaviour by enabling real-time data collection, inspection and detection of structural degradation. According to relevant literature, a number of sensors can be used to monitor track behaviour during the train passing under harsh environments. This paper presents a review of sensors used for structural monitoring of railway track infrastructure, as well as their application to sense the performance of different track components during extreme events. The insight into track monitoring for railways serving traffic with extreme features will not only improve the track inspection and damage detection but also enable a predictive track maintenance regime in order to assist the decision-making process towards more cost-effective management in the railway industry.

/pdf/state-of-the-art-review-of-railway-track-resilience-520j1jk0dq.pdf

Sakdirat Kaewunruen

Papers

Digital twin aided sustainability-based lifecycle management for railway turnout systems

A Digital-Twin Evaluation of Net Zero Energy Building for Existing Buildings

Digital twin for sustainability evaluation of railway station buildings

Enhancement of Dynamic Damping in Eco-Friendly Railway Concrete Sleepers Using Waste-Tyre Crumb Rubber

State-of-the-Art Review of Railway Track Resilience Monitoring