Emulsion-treated aggregate base layer structure is one of the popular choices to form a more stabilized layer, in which aggregates are treated with slow-setting bitumen emulsion. The aim of the study is to propose a three-dimensional finite element model that is capable of showing the potential benefits of using an emulsion-treated aggregate layer. The damaging effect of overloading and high temperature in a tropical climatic condition on the pavement response have been highlighted in this study. The analyses showed that by using an emulsion-treated aggregate layer, the rut resistance and fatigue life considerably improve.

The design of asphalt pavement in many developing nations still relies on an empirical approach, often leading to either premature failure of the pavement or overdesign. The transition from an empirical approach to semi-mechanistic or mechanistic was felt by past researchers, and many advanced tools based on these approaches have been developed. Computational tools, like finite element (FE) analysis, are capable of handling complex material properties of pavement materials under nonuniform loading conditions. Asphalt mixes are widely known to exhibit viscoelastic behaviour based on temperature and loading conditions, while the response of unbound materials under cyclic loading is stress dependent. Due to the complexity of the entire process, numerous pavement design tools treat them as purely elastic materials. This study aims to develop a finite element based, simple, and practical framework to assess the structural response of asphalt pavement under overloading and varying temperature conditions in a tropical climate. The framework offers a straightforward method for the determination of time dependent viscoelastic parameters of the asphalt mixture using creep compliance test. The nonlinear stress-dependent behaviour of unbound granular materials (UGMs) in different layers has also been presented based on repeated load triaxial compression testing. It was concluded that overloading and increasing mix temperature severely affect pavement performance. A 25 % overloading resulted in a reduction of subgrade rutting life by 62.33 %, whereas an increase in mix temperature by 10° C at intermediate temperature reduced asphalt fatigue life by 29.34 % and subgrade rutting life by 42.03 %.

In most of developing countries across the world, pavement design is still based on an empirical approach that may result in premature failure or overdesigned pavements. A shift from an empirical to a semi-mechanistic or mechanistic approach is the need of modern time. In this regard, computational tools such as finite element (FE) are being successfully utilized to gain deeper insights because such tools have allowed researchers to study the complex behaviour of bituminous concrete (BC) materials. It is well recognized that BC material typically exhibits viscoelastic/visco-elasto-plastic behaviour depending on applied loading (including temperature) conditions. However, due to the complexity of the whole procedure yet many pavement design tools consider them as pure elastic material. The aim of this research is to develop FEM based simple and practical framework to evaluate the structural response of BC material with viscoelastic material characterization which can be an effective tool to predict field behaviour with commonly available pavement material tests. Such a framework will be helpful in analysing variations in the critical response of BC pavement with varied traffic loads and ambient temperatures. The framework provides a relatively simple procedure to obtain the viscoelastic parameters of BC mix with a creep compliance test conducted at different temperatures. It was concluded that Creep compliance data if pre-smoothened by the Power law model reduces mathematical optimization issues to some extent. Furthermore, with the obtained parameters, a 3-dimensional FE model was developed to obtain sensitivity to critical stresses, strains, and vertical deformations at desired conditions. Material characterization of unbound granular layers was evaluated through resilient modulus based on empirical relations. Analysis was carried out taking into consideration the traffic load, contact pressure, mix type, air-void, and temperature variation.

A critical review of lab and field measurement methodologies, harmonization in measuring techniques, and modelling of skid resistance of asphalt concrete pavement have been provided. Although several past studies have provided literature review on general topics of skid resistance, to the best of the author's knowledge, none of them have compressively covered the topic considering the status & requirements of developing nations. There has been significant development in speed with the improvement in computational facilities. In modern times, with the improvement in infrastructure quality in developing nations, permitted speeds have also drastically increased. To avoid skid-related accidents, it is important to develop good practices in maintaining sufficient skid resistance. The requirements and the availability of technology might be significantly different in developing nations. The suitability and limitations of various methods used for capturing the skid characteristics of the surface have been outlined. The harmonization in skid resistance measurement using laboratory and field-testing methods has been summarized. Correlation analysis of various in-situ and laboratory test data has been made to maintain a better harmony of measurement either in the field or in the laboratory. In the subsequent sections, progress in the modelling approach (analytical to numerical) has been discussed in brief. Computational capabilities of an analytical and numerical modelling approach for predicting pavement skid resistance characteristics have been reviewed. These models have been developed to consider complex attributes of tire pavement interactions like hydroplaning, temperature rise in the tire, mix morphology, tire inflation, and vehicle acceleration and deceleration for predicting skid resistance. These attributes of skid resistance have been discussed in detail and presented a basic overview of the model development process which is missing in past review studies. Few recent studies on skid resistance measurement and modelling to highlight the use of new technology and improvements over conventional techniques have been presented in the manuscript which has not been reviewed earlier. Critical factors affecting the skid resistance model like hydroplaning, tire-related parameters, temperature, and surface texture have been highlighted in this manuscript. Few key research directions have been suggested as the scope of future study to predict a more reliable skid resistance model.

IoT devices penetrate different aspects of our life including critical services, such as health monitoring, public safety, and autonomous driving. Such safety-critical IoT systems often consist of a large number of devices and need to withstand a vast range of known Denial-of-Service (DoS) network attacks to ensure a reliable operation while offering low-latency information dissemination. As the first solution to jointly achieve these goals, we propose LIDOR, a secure and lightweight multihop communication protocol designed to withstand all known variants of packet dropping attacks. Specifically, LIDOR relies on an end-to-end feedback mechanism to detect and react on unreliable links and draws solely on efficient symmetric-key cryptographic mechanisms to protect packets in transit. We show the overhead of LIDOR analytically and provide the proof of convergence for LIDOR which makes LIDOR resilient even to strong and hard-to-detect wormhole-supported grayhole attacks. In addition, we evaluate the performance via testbed experiments. The results indicate that LIDOR improves the reliability under DoS attacks by up to 91% and reduces network overhead by 32% compared to a state-of-the-art benchmark scheme.