5,421 research outputs found

    Developing A Road Freight Transport Performance Measurement System To Drive Sustainability:An Empirical Study Of Egyptian Road Freight Transport Companies

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    While several road freight performance measurement systems have been developed, only a limited number of quantified performance measurement frameworks encompassing diverse sets of performance metrics from multiple sustainable perspectives are available on a technological platform. These sets of metrics could be integrated as crucial performance indicators for assessing the operational performance of various road freight transport companies. These indicators include fuel efficiency, trip duration, vehicle loading, and cargo capacity. The objective of this research is to construct a conceptual road freight performance measurement framework that comprehensively incorporates performance elements from sustainable viewpoints (economic, environmental, and social), leveraging technology to measure the performance of road freight transport companies. This proposed framework aims to aid these companies in gauging their performance using technology, thus enhancing their operations towards sustainability.Within the road freight transport sector, several challenges exist, with congestion, road infrastructure maintenance, and driver training and qualifications being particularly pressing issues. The developed performance measurement framework offers the means for companies to evaluate the effects of technology integration on vehicles and overall performance. This allows companies to measure their performance from an operational standpoint rather than solely a strategic one, thereby identifying areas requiring improvement. Egypt was chosen as the empirical study location due to its relatively low level of technological integration within its road freight sector.This thesis employs an explanatory mixed methods approach, encompassing four distinct phases. The first phase entails a review to formulate the proposed theoretical performance measurement framework. Subsequently, the second phase involves conducting semi-structured interviews using a Delphi method to both develop a conceptual performance measurement framework and explore the present state of Egypt's road freight transport sector. Following this, the third phase encompasses surveys based on the results derived from Delphi analysis, involving diverse participants from the road freight transport industry. The aim is to validate the developed performance measurement framework through an empirical study conducted in Egypt. Lastly, the fourth phase centres around organizing focus groups involving stakeholders within road freight transport companies. The goal here is to propose a roadmap for implementing the developed road freight transport performance measurement framework within the Egyptian context.The primary theoretical contribution of this research is the development of a road freight transport performance measurement framework that integrates the three sustainability dimensions with technology. Additionally, this study offers practical guidance for the application of the developed framework in various countries and contexts. From a practical standpoint, this research aids road freight transport managers in evaluating their operational performance, thereby identifying challenges, devising action plans, and making informed decisions to mitigate these issues and enhance sustainability-oriented performance. Ultimately, the developed road freight transport performance measurement framework is poised to promote performance measurement aligned with technology, fostering progress towards achieving the sustainable development goals by 2030

    Continuous flow synthesis of hypercrosslinked polymers (HCPs) and its environmental impact evaluation

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    Hypercrosslinked polymers(HCPs) are a class of microporous adsorbents with a wide range of applications, including dye adsorption, and gas storage. Traditionally, HCPs are synthesised through Friedel-Crafts alkylation, which involves a time-consuming synthesis process in batch reactors, posing challenges for scaling up production to meet global demand. The prolong reaction duration issue could be eliminated by means of a new synthetic method to substitute batch reactors. The ultimate aim of this study is to intensify the HCP synthesis process by transitioning from batch reactors to continuous reactors. This shift intents to enhance productivity while maintaining a high specific surface area, crucial for superior adsorption capacity. Additionally, this study aspired to reduce the environmental impact associated with this new method for HCP synthesis. To achieve these objectives, a continuous flow system had been adopted as a replacement for the conventional batch method in HCP synthesis. Three types of HCPs were successfully synthesised using well-established strategies (internally crosslinked, post-crosslinked, and externally crosslinked) in the continuous flow system, showcasing its versatility. The productivity, measured as space-time-yield (STY), of continuous flow synthesis showed an enhancement ranging from 32 – 117-fold when compared to batch synthesis. These improvements were attributed to reducing reaction duration during flow synthesis, from 1440 minutes (24 hours) to 5 – 15 minutes. The specific surface areas of flow-synthesised HCPs were, on average, lower than the batch-synthesised HCPs by 1.5 – 10 %. This meant that when compared to batch-synthesised HCPs, more quantities of flow-synthesised HCPs were needed for dye adsorption and CO2 capture. However, despite this requirement for larger quantities, the environmental assessment of continuous flow synthesis indicated a reduction in negative environmental impacts across most environmental impact indicators. This suggest an improvement in the environmental sustainability of continuous flow HCP synthesis compared to batch synthesis. Furthermore, this study also explored an alternative synthesis method using twin screw extraction (TSE) with deep eutectic solvents (DES), a benign solvent replacement for halogenated solvents, during HCP synthesis. Although this approach offers promising potential as the replacement of continuous flow synthesis using conventional halogenated solvents, further investigations are warranted for its optimisation. In conclusion, this thesis advocates for the adoption of continuous flow synthesis of HCPs, underlining its potential for productivity enhancement and reduced environmental impacts. This study lays the foundation for the potential industrial-scale implementation of continuous flow synthesis, bridging the gap between HCP supply and demand while contributing to lower environmental impacts in the production process

    Deep generative models for network data synthesis and monitoring

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    Measurement and monitoring are fundamental tasks in all networks, enabling the down-stream management and optimization of the network. Although networks inherently have abundant amounts of monitoring data, its access and effective measurement is another story. The challenges exist in many aspects. First, the inaccessibility of network monitoring data for external users, and it is hard to provide a high-fidelity dataset without leaking commercial sensitive information. Second, it could be very expensive to carry out effective data collection to cover a large-scale network system, considering the size of network growing, i.e., cell number of radio network and the number of flows in the Internet Service Provider (ISP) network. Third, it is difficult to ensure fidelity and efficiency simultaneously in network monitoring, as the available resources in the network element that can be applied to support the measurement function are too limited to implement sophisticated mechanisms. Finally, understanding and explaining the behavior of the network becomes challenging due to its size and complex structure. Various emerging optimization-based solutions (e.g., compressive sensing) or data-driven solutions (e.g. deep learning) have been proposed for the aforementioned challenges. However, the fidelity and efficiency of existing methods cannot yet meet the current network requirements. The contributions made in this thesis significantly advance the state of the art in the domain of network measurement and monitoring techniques. Overall, we leverage cutting-edge machine learning technology, deep generative modeling, throughout the entire thesis. First, we design and realize APPSHOT , an efficient city-scale network traffic sharing with a conditional generative model, which only requires open-source contextual data during inference (e.g., land use information and population distribution). Second, we develop an efficient drive testing system — GENDT, based on generative model, which combines graph neural networks, conditional generation, and quantified model uncertainty to enhance the efficiency of mobile drive testing. Third, we design and implement DISTILGAN, a high-fidelity, efficient, versatile, and real-time network telemetry system with latent GANs and spectral-temporal networks. Finally, we propose SPOTLIGHT , an accurate, explainable, and efficient anomaly detection system of the Open RAN (Radio Access Network) system. The lessons learned through this research are summarized, and interesting topics are discussed for future work in this domain. All proposed solutions have been evaluated with real-world datasets and applied to support different applications in real systems

    Authentication enhancement in command and control networks: (a study in Vehicular Ad-Hoc Networks)

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    Intelligent transportation systems contribute to improved traffic safety by facilitating real time communication between vehicles. By using wireless channels for communication, vehicular networks are susceptible to a wide range of attacks, such as impersonation, modification, and replay. In this context, securing data exchange between intercommunicating terminals, e.g., vehicle-to-everything (V2X) communication, constitutes a technological challenge that needs to be addressed. Hence, message authentication is crucial to safeguard vehicular ad-hoc networks (VANETs) from malicious attacks. The current state-of-the-art for authentication in VANETs relies on conventional cryptographic primitives, introducing significant computation and communication overheads. In this challenging scenario, physical (PHY)-layer authentication has gained popularity, which involves leveraging the inherent characteristics of wireless channels and the hardware imperfections to discriminate between wireless devices. However, PHY-layerbased authentication cannot be an alternative to crypto-based methods as the initial legitimacy detection must be conducted using cryptographic methods to extract the communicating terminal secret features. Nevertheless, it can be a promising complementary solution for the reauthentication problem in VANETs, introducing what is known as “cross-layer authentication.” This thesis focuses on designing efficient cross-layer authentication schemes for VANETs, reducing the communication and computation overheads associated with transmitting and verifying a crypto-based signature for each transmission. The following provides an overview of the proposed methodologies employed in various contributions presented in this thesis. 1. The first cross-layer authentication scheme: A four-step process represents this approach: initial crypto-based authentication, shared key extraction, re-authentication via a PHY challenge-response algorithm, and adaptive adjustments based on channel conditions. Simulation results validate its efficacy, especially in low signal-to-noise ratio (SNR) scenarios while proving its resilience against active and passive attacks. 2. The second cross-layer authentication scheme: Leveraging the spatially and temporally correlated wireless channel features, this scheme extracts high entropy shared keys that can be used to create dynamic PHY-layer signatures for authentication. A 3-Dimensional (3D) scattering Doppler emulator is designed to investigate the scheme’s performance at different speeds of a moving vehicle and SNRs. Theoretical and hardware implementation analyses prove the scheme’s capability to support high detection probability for an acceptable false alarm value ≤ 0.1 at SNR ≥ 0 dB and speed ≤ 45 m/s. 3. The third proposal: Reconfigurable intelligent surfaces (RIS) integration for improved authentication: Focusing on enhancing PHY-layer re-authentication, this proposal explores integrating RIS technology to improve SNR directed at designated vehicles. Theoretical analysis and practical implementation of the proposed scheme are conducted using a 1-bit RIS, consisting of 64 × 64 reflective units. Experimental results show a significant improvement in the Pd, increasing from 0.82 to 0.96 at SNR = − 6 dB for multicarrier communications. 4. The fourth proposal: RIS-enhanced vehicular communication security: Tailored for challenging SNR in non-line-of-sight (NLoS) scenarios, this proposal optimises key extraction and defends against denial-of-service (DoS) attacks through selective signal strengthening. Hardware implementation studies prove its effectiveness, showcasing improved key extraction performance and resilience against potential threats. 5. The fifth cross-layer authentication scheme: Integrating PKI-based initial legitimacy detection and blockchain-based reconciliation techniques, this scheme ensures secure data exchange. Rigorous security analyses and performance evaluations using network simulators and computation metrics showcase its effectiveness, ensuring its resistance against common attacks and time efficiency in message verification. 6. The final proposal: Group key distribution: Employing smart contract-based blockchain technology alongside PKI-based authentication, this proposal distributes group session keys securely. Its lightweight symmetric key cryptography-based method maintains privacy in VANETs, validated via Ethereum’s main network (MainNet) and comprehensive computation and communication evaluations. The analysis shows that the proposed methods yield a noteworthy reduction, approximately ranging from 70% to 99%, in both computation and communication overheads, as compared to the conventional approaches. This reduction pertains to the verification and transmission of 1000 messages in total

    Strategy Tripod Perspective on the Determinants of Airline Efficiency in A Global Context: An Application of DEA and Tobit Analysis

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    The airline industry is vital to contemporary civilization since it is a key player in the globalization process: linking regions, fostering global commerce, promoting tourism and aiding economic and social progress. However, there has been little study on the link between the operational environment and airline efficiency. Investigating the amalgamation of institutions, organisations and strategic decisions is critical to understanding how airlines operate efficiently. This research aims to employ the strategy tripod perspective to investigate the efficiency of a global airline sample using a non-parametric linear programming method (data envelopment analysis [DEA]). Using a Tobit regression, the bootstrapped DEA efficiency change scores are further regressed to determine the drivers of efficiency. The strategy tripod is employed to assess the impact of institutions, industry and resources on airline efficiency. Institutions are measured by global indices of destination attractiveness; industry, including competition, jet fuel and business model; and finally, resources, such as the number of full-time employees, alliances, ownership and connectivity. The first part of the study uses panel data from 35 major airlines, collected from their annual reports for the period 2011 to 2018, and country attractiveness indices from global indicators. The second part of the research involves a qualitative data collection approach and semi-structured interviews with experts in the field to evaluate the impact of COVID-19 on the first part’s significant findings. The main findings reveal that airlines operate at a highly competitive level regardless of their competition intensity or origin. Furthermore, the unpredictability of the environment complicates airline operations. The efficiency drivers of an airline are partially determined by its type of business model, its degree of cooperation and how fuel cost is managed. Trade openness has a negative influence on airline efficiency. COVID-19 has toppled the airline industry, forcing airlines to reconsider their business model and continuously increase cooperation. Human resources, sustainability and alternative fuel sources are critical to airline survival. Finally, this study provides some evidence for the practicality of the strategy tripod and hints at the need for a broader approach in the study of international strategies

    Hybrid energy system integration and management for solar energy: a review

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    The conventional grid is increasingly integrating renewable energy sources like solar energy to lower carbon emissions and other greenhouse gases. While energy management systems support grid integration by balancing power supply with demand, they are usually either predictive or real-time and therefore unable to utilise the full array of supply and demand responses, limiting grid integration of renewable energy sources. This limitation is overcome by an integrated energy management system. This review examines various concepts related to the integrated energy management system such as the power system configurations it operates in, and the types of supply and demand side responses. These concepts and approaches are particularly relevant for power systems that rely heavily on solar energy and have constraints on energy supply and costs. Building on from there, a comprehensive overview of current research and progress regarding the development of integrated energy management system frameworks, that have both predictive and real-time energy management capabilities, is provided. The potential benefits of an energy management system that integrates solar power forecasting, demand-side management, and supply-side management are explored. Furthermore, design considerations are proposed for creating solar energy forecasting models. The findings from this review have the potential to inform ongoing studies on the design and implementation of integrated energy management system, and their effect on power systems

    Climate Change and Critical Agrarian Studies

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    Climate change is perhaps the greatest threat to humanity today and plays out as a cruel engine of myriad forms of injustice, violence and destruction. The effects of climate change from human-made emissions of greenhouse gases are devastating and accelerating; yet are uncertain and uneven both in terms of geography and socio-economic impacts. Emerging from the dynamics of capitalism since the industrial revolution — as well as industrialisation under state-led socialism — the consequences of climate change are especially profound for the countryside and its inhabitants. The book interrogates the narratives and strategies that frame climate change and examines the institutionalised responses in agrarian settings, highlighting what exclusions and inclusions result. It explores how different people — in relation to class and other co-constituted axes of social difference such as gender, race, ethnicity, age and occupation — are affected by climate change, as well as the climate adaptation and mitigation responses being implemented in rural areas. The book in turn explores how climate change – and the responses to it - affect processes of social differentiation, trajectories of accumulation and in turn agrarian politics. Finally, the book examines what strategies are required to confront climate change, and the underlying political-economic dynamics that cause it, reflecting on what this means for agrarian struggles across the world. The 26 chapters in this volume explore how the relationship between capitalism and climate change plays out in the rural world and, in particular, the way agrarian struggles connect with the huge challenge of climate change. Through a huge variety of case studies alongside more conceptual chapters, the book makes the often-missing connection between climate change and critical agrarian studies. The book argues that making the connection between climate and agrarian justice is crucial
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