Emergy-based life cycle assessment (Em-LCA) of multi-unit and single-family residential buildings in Canada

AbstractThe construction and building process depends on substantial consumption of natural resources with far-reaching impacts beyond their development area. In general, a significant portion of annual resource consumption by the building and construction industry is a result of applying traditional building strategies and practices such as designing and selecting types of development (e.g. multi-unit condo and single-family house, etc.), building materials and structure, heating/cooling systems, and planning renovation and maintenance practices. On the other hand, apart from structural suitability, building developers mostly consider the basic requirements of public owners or private occupants of the buildings, where the main criteria for selecting building strategies are costs, and long-term environmental and socio-economic impacts are generally ignored. The main purpose of this paper is to develop an improved building sustainability assessment framework to measure and integrate different sustainability factors, i.e. long-term environmental upstream and downstream impacts and associated socio-economic costs, in a unified and quantitative basis. The application of the proposed framework has been explained through a case study of single-family houses and multi-unit residential buildings in Canada. A comprehensive framework based on the integration of emergy synthesis and life cycle assessment (LCA) has been developed and applied. The results of this research prove that the proposed emergy-based life cycle assessment (Em-LCA) framework offers a practical sustainability assessment tool by providing quantitative and transparent results for informed decision-making

Contractual obligations analysis for construction waste management in Canada

Construction industry creates a massive amount of waste, which typically ends up in landfills. Canadian construction industry represents 30% of the total municipal solid waste deposited in landfills. Construction and demolition (C&D) waste has created negative socioeconomic and environmental impacts including contaminating ground water, emitting greenhouse gases, and adding more waste to scarce landfills. Literature is cited rework/waste generation due to ambiguity/errors in construction contract documents. Exculpatory clauses in contract documents are included in contractual agreements to prevent contractor claims, which often cause rework. After an extensive contract documents review, these clauses were categorized in to eight major areas. This paper (1) analyses expert opinions on pre-identified contractual clauses; and (2) introduces recommendations to minimize rework and waste in construction projects. It was found that the clauses related to quality, workmanship, and field quality control/inspection have the most potential to generate construction waste

A new weighting factor in combining belief function

Dempster-Shafer evidence theory has been widely used in various applications. However, to solve the problem of counter-intuitive outcomes by using classical Dempster-Shafer combination rule is still an open issue while fusing the conflicting evidences. Many approaches based on discounted evidence and weighted average evidence have been investigated and have made significant improvements. Nevertheless, all of these approaches have inherent flaws. In this paper, a new weighting factor is proposed to address this proble

Evaluating motivation of construction workers: a comparison of fuzzy rule-based model with the traditional expectancy theory

Measuring workers’ performance and the level of motivation is of paramount importance as the productivity of workers at a workplace primarily depends upon their level of motivation. However, measuring the level of workers’ motivation at workplace is not always straightforward because the workers’ motivation is a function of various personal and external factors. This paper proposes a fuzzy rule-based model for evaluating the motivation level of construction workers using their working patterns. The motivation level evaluated using the fuzzy rule-based model was compared with motivational levels determined by the traditional Vroom’s expectancy theory or Expectancy-Instrumentality-Va­lence (EIV) method. EIV method used questionnaire surveys and interviews to determine workers’ motivation. The results of fuzzy rule-based models aligned closely with the EIV model, especially for the middle range of motivation levels. Compared to traditional EIV model, the fuzzy rule-based system is simple to implement and found to be very pragmatic in construction field settings

Smart city and resilient city: Differences and connections

Smart city (SC) and resilient city (RC) have been studied and practiced over the years in terms of the increasing urban problems and disasters. However, there is a large overlap between their meanings and relationships. With an increasing concern for both SC and RC in urban development and hazard mitigation, a review was conducted to explore the differences and connections between SC and RC with scientometric analysis. There are far more literatures about SC than RC, and very few papers discuss SC and RC together. The research trend, category, and hotspots from research clusters are illustrated and compared. Major differences are discussed from their objectives, driving force, current research focus, and criticism. The literatures both related to SC and RC are used to explore their connections, which are very limited. The results revealed that the RC's impact on SC are positive from physical, social, and environmental aspects, while SC's impacts on RC could be both positive and negative from the above three aspects. It is indicated that SC and RC are both important for urban planning and can be complementary to each other through proper design and governance, which implies the need for building a resilient smart city (RSC). This article is categorized under: Technologies > Structure Discovery and Clustering Technologies > Visualization

Towards Secure Synchronous Communication Architectures for Wireless Networks

The vision behind the Internet of Things (IoT) revolves around creating a connected ecosystem where devices, people, and systems collaborate seamlessly, unlocking new possibilities, improving efficiency, and enhancing our daily lives. IoT encloses many device classes, including low-power wireless devices that rely on batteries or energy harvesting. Due to the low-power nature and the instability of the wireless links, networks comprising these IoT devices are commonly known as Low-power and Lossy Networks (LLNs). Several network-wide flooding-based communication primitives that employ synchronous transmissions have emerged as an alternative to traditional multi-hop routing, thereby creating a new dimension of LLN research. While these primitives have demonstrated superior performance in terms of latency and reliability, they have received little attention regarding network security. In this dissertation, we study the effectiveness of several attacks that strive to disrupt synchronous transmission-based protocols. Based on the findings from this work, we examine the security requirements and propose encryption and lightweight flood verification methods to protect synchronous transmission-based flooding protocols from these attacks. Realising the IoT's vision demands employing well-established communication technologies like the Internet Protocol (IP) suite protocols to ensure interoperability. However, the IP suite protocols are not explicitly designed for low-power networks; hence using them in LLNs encounters numerous challenges. Some of my work included in this dissertation focuses on the performance issues of two widely used IP suite protocols: Transmission Control Protocol (TCP) and Datagram Transport Layer Security (DTLS). We propose to replace the conventional link layer protocols of the LLN  stacks with a synchronous transmission-based protocol to enhance the reliability that TCP expects in lower layers, thereby improving the TCP performance. We introduce novel header compression mechanisms to reduce the size of DTLS messages without violating end-to-end security. Reducing the size of DTLS messages lowers the transmission overhead, improving its performance in LLNs. Optical Wireless Communication (OWC) is a complementary technology to radio frequency communication. Specifically, visible light communication (VLC) has proven its capability to offer higher data transfer rates, enabling faster and more efficient communication. The last work of this dissertation draws inspiration from synchronous transmissions in LLNs and presents an OWC-based time synchronisation system for high-speed VLC access points to synchronise their transmissions. This time synchronisation system has a considerably lower synchronisation jitter than the widely-used Precision Time Protocol (PTP)

Towards Secure Synchronous Communication Architectures for Wireless Networks

The vision behind the Internet of Things (IoT) revolves around creating a connected ecosystem where devices, people, and systems collaborate seamlessly, unlocking new possibilities, improving efficiency, and enhancing our daily lives. IoT encloses many device classes, including low-power wireless devices that rely on batteries or energy harvesting. Due to the low-power nature and the instability of the wireless links, networks comprising these IoT devices are commonly known as Low-power and Lossy Networks (LLNs). Several network-wide flooding-based communication primitives that employ synchronous transmissions have emerged as an alternative to traditional multi-hop routing, thereby creating a new dimension of LLN research. While these primitives have demonstrated superior performance in terms of latency and reliability, they have received little attention regarding network security. In this dissertation, we study the effectiveness of several attacks that strive to disrupt synchronous transmission-based protocols. Based on the findings from this work, we examine the security requirements and propose encryption and lightweight flood verification methods to protect synchronous transmission-based flooding protocols from these attacks. Realising the IoT's vision demands employing well-established communication technologies like the Internet Protocol (IP) suite protocols to ensure interoperability. However, the IP suite protocols are not explicitly designed for low-power networks; hence using them in LLNs encounters numerous challenges. Some of my work included in this dissertation focuses on the performance issues of two widely used IP suite protocols: Transmission Control Protocol (TCP) and Datagram Transport Layer Security (DTLS). We propose to replace the conventional link layer protocols of the LLN  stacks with a synchronous transmission-based protocol to enhance the reliability that TCP expects in lower layers, thereby improving the TCP performance. We introduce novel header compression mechanisms to reduce the size of DTLS messages without violating end-to-end security. Reducing the size of DTLS messages lowers the transmission overhead, improving its performance in LLNs. Optical Wireless Communication (OWC) is a complementary technology to radio frequency communication. Specifically, visible light communication (VLC) has proven its capability to offer higher data transfer rates, enabling faster and more efficient communication. The last work of this dissertation draws inspiration from synchronous transmissions in LLNs and presents an OWC-based time synchronisation system for high-speed VLC access points to synchronise their transmissions. This time synchronisation system has a considerably lower synchronisation jitter than the widely-used Precision Time Protocol (PTP)

Towards a secure synchronous communication architecture for low-power wireless networks

The Internet of Things (IoT) is becoming the future Internet where most day-to-day devices are connected to the Internet. These devices are often resource constrained and use low-power wireless communication. Hence networks of them are called low-power and lossy networks (LLNs). LLN devices may be used in critical applications such as health care, traffic and industrial plants that concern privacy and security, thus their communication has to be protected from malicious activities. LLNs face threats at different levels ranging from transmitting bits wirelessly to applications. In this thesis, we primarily explore LLN security issues related to application protocols and attacks that target the availability of LLNs. Particularly, we investigate compressing messages of a transport security protocol, DTLS, to make it efficient for LLNs. The IETF proposes to use DTLS for securing CoAP, a specialized web protocol for constrained devices. Furthermore, we experimentally study disrupting the communication of one of the state of the art LLN protocols, Glossy, by attacking its core mechanism. Secondarily, we aim at improving the performance of TCP in LLNs with mobility over a reliable data link protocol. To this end, we use a Glossy-based communication protocol, LWB, as a reliable data link protocol. We plan to use the evaluation of this work as a stepping stone towards comparing the performance of secure Glossy-based communication protocols. The main contributions of this thesis are threefold. We propose novel message compression mechanisms for DTLS messages. We also present novel attacks on Glossy, evaluate the effectiveness of them experimentally, and propose potential counter measures. Finally, we show that a reliable data link protocol can improve the performance of TCP in static and mobile settings

Towards a secure synchronous communication architecture for low-power wireless networks

The Internet of Things (IoT) is becoming the future Internet where most day-to-day devices are connected to the Internet. These devices are often resource constrained and use low-power wireless communication. Hence networks of them are called low-power and lossy networks (LLNs). LLN devices may be used in critical applications such as health care, traffic and industrial plants that concern privacy and security, thus their communication has to be protected from malicious activities. LLNs face threats at different levels ranging from transmitting bits wirelessly to applications. In this thesis, we primarily explore LLN security issues related to application protocols and attacks that target the availability of LLNs. Particularly, we investigate compressing messages of a transport security protocol, DTLS, to make it efficient for LLNs. The IETF proposes to use DTLS for securing CoAP, a specialized web protocol for constrained devices. Furthermore, we experimentally study disrupting the communication of one of the state of the art LLN protocols, Glossy, by attacking its core mechanism. Secondarily, we aim at improving the performance of TCP in LLNs with mobility over a reliable data link protocol. To this end, we use a Glossy-based communication protocol, LWB, as a reliable data link protocol. We plan to use the evaluation of this work as a stepping stone towards comparing the performance of secure Glossy-based communication protocols. The main contributions of this thesis are threefold. We propose novel message compression mechanisms for DTLS messages. We also present novel attacks on Glossy, evaluate the effectiveness of them experimentally, and propose potential counter measures. Finally, we show that a reliable data link protocol can improve the performance of TCP in static and mobile settings