Search Results (21)

Geopolymer mortar is an eco-friendly type of mortar that is mainly made of fly ash, slag, and sand as common precursors. Recently, the availability of these materials has become limited due to the huge increase in geopolymer constructions. This is aligned with the recent demand for recycling construction and demolition waste (CDW). In this study, brick waste (BW), ceramic tile waste (CTW), roof tile waste (RTW), and glass waste (GW) extracted from CDW were prepared in the following two sizes: one equivalent to the traditional geopolymer mortar binder (fly ash and slag) size and the other one equivalent to the sand size. The prepared CDW was used to partially replace the binder or sand to produce high-strength geopolymer mortar (HSGM). The replacements were carried out at rates of 25% and 50% by volume. The variety of mechanical and durability characteristics were measured, including workability, compressive strength, freezing/thawing resistance, sulfate attack, water sorptivity, and water absorption. Three curing conditions were applied for the proposed HSGM in this study, namely, water, heat followed by water, and heat followed by air. The results showed that the compressive strength of all HSGM mixes containing CDW ranged from 24 to 104 MPa. HSGM mixes cured in heat followed by water showed the highest 28-day compressive strengths of 104 MPa (when using 25% BW binder), 84.5 MPa (when using 25% BW fine aggregate), 91.3 MPa (when using 50% BW fine aggregate), 84 MPa (when using 25% CTW binder), and 94 MPa (when using 25% CTW fine aggregate). The findings demonstrated that using BW provided good resistance to freezing/thawing and sulfate attack. The water absorption of HSGM increased by 57.8% when using 50% CTW fine aggregate and decreased by 26.5% when using 50% GW fine aggregate. The highest water sorptivity of HSGM was recorded when 50% CTW fine aggregate was used. The use of CDW in HSGM helps reduce the depletion of natural resources and minimizes waste accumulation, enhancing environmental sustainability. These benefits make HSGM an eco-friendly alternative that promotes circular economy practices. Full article

Ternary blended cements, made with silica fume and limestone, provide significant benefits such as improved compressive strength, chloride penetration resistance, sulfates attack, etc. Furthermore, they could be considered low-carbon cements, and they contribute to reducing the depletion of natural resources in reference to water usage, fossil fuel consumption, and mining. Limestone (10%, 15%, and 20%) with different fineness and coarse silica fume (3%, 5%, and 7%) was used to produce ternary cements. The average size of coarse silica fume used was 238 μm. For the first time, the carbonation resistance of ternary Portland cements made with silica fume and limestone has been assessed. The carbonation resistance was assessed by natural carbonation testing. The presence of coarse silica fume and limestone in the blended cement led to pore refinement of the cement-based materials by the filling effect and the C-S-H gel formation. Accordingly, the carbonation resistance of these new ternary cements was less poor than expected for blended cements. Full article

The relentlessly depleting fossil-fuel-based energy resources worldwide have forbidden an imminent energy crisis that could severely impact the general population. This dire situation calls for the immediate exploitation of renewable energy resources to redress the balance between power consumption and generation. This manuscript confers about energy management tactics to optimize the methods of power production and consumption. Furthermore, this paper also discusses the solutions to enhance the reliability of the electrical power system. In order to elucidate the enhanced reliability of the electrical system, microgrids consisting of different energy resources, load types, and optimization techniques are comprehensively analyzed to explore the significance of energy management systems (EMSs) and demand response strategies. Subsequently, this paper discusses the role of EMS for the proper consumption of electrical power considering the advent of electric vehicles (EVs) in the energy market. The main reason to integrate EVs is the growing hazards of climate change due to carbon emissions. Moreover, this paper sheds light on the growing importance of artificial intelligence (AI) in the technological realm and its incorporation into electrical systems with the notion of strengthening existing smart grid technologies and to handle the uncertainties in load management. This paper also delineates the different methodologies to effectively mitigate the probability of facing cyber-attacks and to make the smart grids invulnerable. Full article

As drones are widely employed in various industries and daily life, concerns regarding their safety have been gradually emerging. Denial of service (DoS) attacks have become one of the most significant threats to the stability of resource-constrained sensor nodes. Traditional brute-force and high-rate distributed denial of service (DDoS) attacks are easily detectable and mitigated. However, low-rate TCP DoS attacks can considerably impair TCP throughput and evade DoS prevention systems by inconspicuously consuming a small portion of network capacity, and whereas the literature offers effective defense mechanisms against DDoS attacks, there is a gap in defending against Low-Rate TCP DoS attacks. In this paper, we introduce AccFlow, an incrementally deployable Software-Defined Networking (SDN)-based protocol designed to counter low-rate TCP DoS attacks. The main idea of AccFlow is to make the attacking flows accountable for the congestion by dropping their packets according to their loss rates. AccFlow drops their packets more aggressively as the loss rates increase. Through extensive simulations, we illustrate that AccFlow can effectively safeguard against low-rate TCP DoS attacks, even when attackers employ varying strategies involving different scales and data rates. Furthermore, whereas AccFlow primarily addresses low-rate TCP DoS attacks, our research reveals its effectiveness in defending against general DoS attacks. These general attacks do not rely on the TCP retransmission timeout mechanism but rather deplete network resources, ultimately resulting in a denial of service for legitimate users. Additionally, we delve into the scalability of AccFlow and its viability for practical deployment in real-world networks. Finally, we demonstrate the effectiveness of AccFlow in safeguarding network resources. Full article

In recent times, distributed denial of service (DDoS) has been one of the most prevalent security threats in internet-enabled networks, with many internet of things (IoT) devices having been exploited to carry out attacks. Due to their inherent security flaws, the attacks seek to deplete the resources of the target network by flooding it with numerous spoofed requests from a distributed system. Research studies have demonstrated that a DDoS attack has a considerable impact on the target network resources and can result in an extended operational outage if not detected. The detection of DDoS attacks has been approached using a variety of methods. In this paper, a comprehensive survey of the methods used for DDoS attack detection on selected internet-enabled networks is presented. This survey aimed to provide a concise introductory reference for early researchers in the development and application of attack detection methodologies in IoT-based applications. Unlike other studies, a wide variety of methods, ranging from the traditional methods to machine and deep learning methods, were covered. These methods were classified based on their nature of operation, investigated as to their strengths and weaknesses, and then examined via several research studies which made use of each approach. In addition, attack scenarios and detection studies in emerging networks such as the internet of drones, routing protocol based IoT, and named data networking were also covered. Furthermore, technical challenges in each research study were identified. Finally, some remarks for enhancing the research studies were provided, and potential directions for future research were highlighted. Full article

Limiting the consumption of nonrenewable resources and minimizing waste production and associated gas emissions are the main priority of the construction sector to achieve a sustainable future. This study investigates the sustainability performance of newly developed binders known as alkali-activated binders (AABs). These AABs work satisfactorily in creating and enhancing the concept of greenhouse construction in accordance with sustainability standards. These novel binders are founded on the notion of utilizing ashes from mining and quarrying wastes as raw materials for hazardous and radioactive waste treatment. The life cycle assessment, which depicts material life from the extraction of raw materials through the destruction stage of the structure, is one of the most essential sustainability factors. A recent use for AAB has been created, such as the use of hybrid cement, which is made by combining AAB with ordinary Portland cement (OPC). These binders are a successful answer to a green building alternative if the techniques used to make them do not have an unacceptable negative impact on the environment, human health, or resource depletion. The Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) software was employed for choosing the optimal materials’ alternative depending on the available criteria. The results revealed that AAB concrete provided a more ecologically friendly alternative than OPC concrete, higher strength for comparable water/binder ratio, and better performance in terms of embodied energy, resistance to freeze–thaw cycles, high temperature resistance, and mass loss due to acid attack and abrasion. Full article

The network system has become an indispensable component of modern infrastructure. DDoS attacks and their variants remain a potential and persistent cybersecurity threat. DDoS attacks block services to legitimate users by incorporating large amounts of malicious traffic in a short period or depleting system resources through methods specific to each client, causing the victim to lose reputation, finances, and potential customers. With the advancement and maturation of artificial intelligence technology, machine learning and deep learning are widely used to detect DDoS attacks with significant success. However, traditional supervised machine learning must depend on the categorized training sets, so the recognition rate plummets when the model encounters patterns outside the dataset. In addition, DDoS attack techniques continue to evolve, rendering training based on conventional data models unable to meet contemporary requirements. Since closed-set classifiers have excellent performance in cybersecurity and are quite mature, this study will investigate the identification of open-set recognition issues where the attack pattern does not accommodate the distribution learned by the model. This research proposes a framework that uses reconstruction error and distributes hidden layer characteristics to detect unknown DDoS attacks. This study will employ deep hierarchical reconstruction nets (DHRNet) architecture and reimplement it with a 1D integrated neural network employing loss function combined with spatial location constraint prototype loss (SLCPL) as a solution for open-set risks. At the output, a one-class SVM (one-class support vector machine) based on a random gradient descent approximation is used to recognize the unknown patterns in the subsequent stage. The model achieves an impressive detection rate of more than 99% in testing. Furthermore, the incremental learning module utilizing unknown traffic labeled by telecom technicians during tracking has enhanced the model’s performance by 99.8% against unknown threats based on the CICIDS2017 Friday open dataset. Full article

Carbon footprint reduction, recompense depletion of natural resources, as well as waste recycling are nowadays focused research directions to achieve sustainability without compromising the concrete strength parameters. Therefore, the purpose of the present study is to utilize different dosages of marble waste aggregates (MWA) and stone dust (SD) as a replacement for coarse and fine aggregate, respectively. The MWA with 10 to 30% coarse aggregate replacement and SD with 40 to 50% fine aggregate replacement were used to evaluate the physical properties (workability and absorption), durability (acid attack resistance), and strength properties (compressive, flexural, and tensile strength) of concrete. Moreover, statistical modeling was also performed using response surface methodology (RSM) to design the experiment, optimize the MWA and SD dosages, and finally validate the experimental results. Increasing MWA substitutions resulted in higher workability, lower absorption, and lower resistance to acid attack as compared with controlled concrete. However, reduced compressive strength, flexural strength, and tensile strength at 7-day and 28-day cured specimens were observed as compared to the controlled specimen. On the other hand, increasing SD content causes a reduction in workability, higher absorption, and lower resistance to acid attack compared with controlled concrete. Similarly, 7-day and 28-day compressive strength, flexural strength, and tensile strength of SD-substituted concrete showed improvement up to 50% replacement and a slight reduction at 60% replacement. However, the strength of SD substituted concrete is higher than controlled concrete. Quadratic models were suggested based on a higher coefficient of determination (R²) for all responses. Quadratic RSM models yielded R² equaling 0.90 and 0.94 for compressive strength at 7 days and 28 days, respectively. Similarly, 0.94 and 0.96 for 7-day and 28-day flexural strength and 0.89 for tensile strength. The optimization performed through RSM indicates that 15% MWA and 50% SD yielded higher strength compared to all other mixtures. The predicted optimized data was validated experimentally with an error of less than 5%. Full article

The increasing incidence of distributed denial-of-service (DDoS) attacks has made software-defined networking (SDN) more vulnerable to the depletion of controller resources. DDoS attacks prevent the SDN controller from processing all incoming data efficiently, potentially disrupting a network or denying legitimate users access to network services. Thus, the protection of the SDN controller is crucial, especially from the ones that exploit the SDN characteristics. In this paper, the authors propose an efficient detection approach for low- and high-rate DDoS attacks on the controller with a high detection rate and a low false positive rate by adapting a dynamic threshold algorithm rather than a static one and proposing a new rule-based detection mechanism. In addition, the proposed approach was evaluated using eight simulation scenarios representing all potential attacks against the SDN controller in terms of attack traffic rates (low or high), sources (either single or multiple hosts), and targets (single or multiple victims). The experiment results show that the proposed approach is more effective than the existing approaches based on attack detection and false positive rates. Full article

The endoparasitoid body size hypothesis suggests that the size of larvae that develop in a single host should be subject to a trade-off: larger size could lead to increase overall fitness but could simultaneously increase the risk of resource depletion and starvation, resulting in a body size just below the host holding capacity. However, this hypothesis has not been rigorously tested using mathematical models thus far. The camellia weevil, C.styracis (Coleoptera: Curculionidae), is a notorious pest attacking fruits of Camellia oleifera Abel. and C. meiocarpa Hu., in which the larvae develop within a single fruit and larval development is limited by the available food resources. We developed a feasible method to test this hypothesis. First, five models were used to describe the relationship between larval mass and host size. Then, the minimum fruit threshold that had to be met for ad libitum larval development and the corresponding larval size (W_a) of this threshold were calculated based on the characteristics of the optimal model. Finally, the difference between the measured larval size and the predicted larval size (W_a) was determined. The results showed that (1) the data were better described by a logistic function than any other equation; (2) larval size in both host plants increased with increasing fruit size until leveling off when the fruits were large enough to allow unconstrained larval development; (3) larval size remained just below the host-fruit holding capacity, as there was no difference between the measured and predicted larval sizes (W_a); and (4) larvae developed in host plant with larger fruits had a larger size. These results confirmed the endoparasitoid body size hypothesis. Full article

This paper proposes a routing protocol for wireless sensor networks to deal with energy-depleting vampire attacks. This resource-conserving protection against energy-draining (RCPED) protocol is compatible with existing routing protocols to detect abnormal signs of vampire attacks and identify potential attackers. It responds to attacks by selecting routes with the maximum priority, where priority is an indicator of energy efficiency and estimation of security level calculated utilizing an analytic hierarchy process (AHP). RCPED has no dependence on cryptography, which consumes less energy and hardware resources than previous approaches. Simulation results show the benefits of RCPED in terms of energy efficiency and security awareness. Full article

Clay bricks are extensively used as building material worldwide. Natural soil deposits are in constant reduction due to the frequent use of clay to manufacture bricks. About 1600 billion bricks are produced annually by the consumption of millions of tons of natural resources. The prime focus of this study is to assess the feasibility of using a composite mixture of waste brick powder (WBP) and waste ceramic powder (WCP) as a replacement for depleting natural resource “clay” in brick manufacturing. Based upon the previous studies, the replacement levels were kept as (4 + 5)%, (8 + 10)%, and (12 + 15)% of WCP and WBP, respectively. The brick specimens were evaluated in terms of compressive strength, modulus of rupture, density, water absorption, efflorescence, apparent porosity, resistance to chemical attack and sulfate attack, and freeze-thaw resistance. The study reveals that about 27% of clay can be replaced with ceramic waste powder and waste brick powder, which can preserve a massive amount of natural clay without compromising the quality of the bricks. Full article

Distributed denial of service (DDoS) attacks aim to deplete the network bandwidth and computing resources of targeted victims. Low-rate DDoS attacks exploit protocol features such as the transmission control protocol (TCP) three-way handshake mechanism for connection establishment and the TCP congestion-control induced backoffs to attack at a much lower rate and still effectively bring down the targeted network and computer systems. Most of the statistical and machine/deep learning-based detection methods proposed in the literature require keeping track of packets by flows and have high processing overheads for feature extraction. This paper presents a novel two-stage model that uses Long Short-Term Memory (LSTM) and Random Forest (RF) to detect the presence of attack flows in a group of flows. This model has a very low data processing overhead; it uses only two features and does not require keeping track of packets by flows, making it suitable for continuous monitoring of network traffic and on-the-fly detection. The paper also presents an LSTM Autoencoder to detect individual attack flows with high detection accuracy using only two features. Additionally, the paper presents an analysis of a support vector machine (SVM) model that detects attack flows in slices of network traffic collected for short durations. The low-rate attack dataset used in this study is made available to the research community through GitHub. Full article

Sustainable development in civil engineering is the clear and necessary goal of the current generation. There are many possibilities for reducing the use of depletable resources. One of them is to use renewable and recyclable materials on a larger scale in the construction industry. One possibility is the application of natural thermal insulators. A typical example is a crushed straw, which is generated as agricultural waste in the Czech Republic. Due to its small dimensions and good thermal insulation parameters, this material can also be used as blown thermal insulation. The research aims to examine the fire resistance of crushed straw as blown insulation. The single-flame source fire test results, thermal attack by a single burning item (SBI) test and large-scale test of a perimeter wall segment are shown. The results show that blown insulation made of crushed straw meets the requirements of fire protection. In addition, crushed straw can be also used to protect load-bearing structures due to its behaviour. This article also shows the production process of crushed straw used as blown insulation in brief. Full article

Nowadays the environment and its natural resources face many issues, related to the depletion of natural resources beside the increase in environmental pollution resulted from uncontrolled plastic waste disposal. Therefore, it is important to find effective and feasible solutions to utilize these wastes, such as using them to produce environmentally friendly green concrete. In this study, plastic-based green lightweight aggregates (PGLAs) containing PET plastic waste and by product additives were developed, and their subsequent physical and mechanical properties were compared with those of reference aggregates. Then, green lightweight aggregate concrete mixes (GLACs) were produced at 100% replacement of normal weight and lightweight coarse aggregate with developed PGLAs; and their fresh, hardened, microscopic and durability-related properties were compared to those of control mixes. Study results revealed that the unit weight of PGLAs were 21% to 29% less than that of normal coarse aggregate. Additionally, PGLAs had low water absorption that varied between 1.2% and 1.6%. The developed aggregates had 45% higher strength compared to that of lightweight coarse aggregate. Study results confirmed that structural green lightweight aggregate concretes (GLACs), that satisfied the dry density, compressive and splitting tensile strength requirements specified in ASTM C330, were feasibly produced. Finally, GLACs had low-to-moderate chloride penetration in accordance with ASTM C1202, thus it can be used in those areas exposed to the risk of chloride attack. Full article