Petrographic,mechanical and chemical properties of sand resources in Lebanon,eastern mediterranean

In a previous study, the results of extensive surveys and investigations covering 80 percent of the Lebanese territory to locate the major sand resources, were reported. Forty-one samples representing major operating sand quarries or sand excavation sites were located, described, and sampled. The research program reported in this paper was designed to evaluate the 41 sand samples based on petrographic analysis, mechanical and chemical acceptance tests, and results of tests conducted on fresh and hardened concrete samples identical except for the type of sand. Conclusions are presented concerning each sand source. In general, Lebanese sands were found to be fine, poorly graded, and rich with material finer than #200 sieve (0.075 mm). The gradation of the sands used was found to have the most significant effect on concrete compressive strength. Because of the scarcity of construction material resources, techniques are presented to improve the gradation of Lebanese sands and to clean them from excessive deleterious substances.     

Modulated relay based stable election protocol for large-scale wireless sensor networks

Internet of things (IoT) applications based on wireless sensor networks (WSNs) have recently gained vast momentum. These applications vary from health care, smart cities, and military applications to environmental monitoring and disaster prevention. As a result, energy consumption and network lifetime have become the most critical research area of WSNs. Through energy-efficient routing protocols, it is possible to reduce energy consumption and extend the network lifetime for WSNs. Using hybrid routing protocols that incorporate multiple transmission methods is an effective way to improve network performance. This paper proposes modulated R-SEP (MR-SEP) for large-scale WSN-based IoT applications. MR-SEP is based on the well-known stable election protocol (SEP). MR-SEP defines three initial energy levels for the nodes to improve the network energy distribution and establishes multi-hop communication between the cluster heads (CHs) and the base station (BS) through relay nodes (RNs) to reduce the energy consumption of the nodes to reach the BS. In addition, MR-SEP reduces the replacement frequency of CHs, which helps increase network lifetime and decrease power consumption. Simulation results show that MR-SEP outperforms SEP, LEACH, and DEEC protocols by 70.2%, 71.58%, and 74.3%, respectively, in terms of lifetime and by 86.53%, 86.68%, and 86.93% in terms of throughput.     

Refractive Index Measurements using a CCD

We measure the refractive index of materials using a CCD camera with a laser beam profiler in the familiar Brewster's angle experiment. This allows us to isolate quickly and accurately the Brewster's angle close to the resolution of the sample rotation stage. The uncertainty in the index of refraction measurement is similar to that of the standard minimum-deviation technique.     

Space partitioning in piecewise metamodeling: a graphical approach

This paper presents a graphically-based space-partitioning methodology for piecewise metamodel building. The method is based on using data displays—in particular, the so-called ordinal plots—leading to a metamodel with acceptable prediction accuracy on a piece-by-piece basis, not just on average. The proposed methodology is general and can be applied to various metamodel types. A one-dimensional example is first used to demonstrate the approach, then the methodology is tested on a number of analytical examples in higher dimensions, one of which corresponds to an electronic filter.     

Denial of service detection using dynamic time warping

With the rapid growth of security threats in computer networks, the need for developing efficient security-warning systems is substantially increasing. Distributed denial-of-service (DDoS) and DoS attacks are still among the most effective and dreadful attacks that require robust detection. In this work, we propose a new method to detect TCP DoS/DDoS attacks. Since analyzing network traffic is a promising approach, our proposed method utilizes network traffic by decomposing the TCP traffic into control and data planes and exploiting the dynamic time warping (DTW) algorithm for aligning these two planes with respect to the minimum Euclidean distance. By demonstrating that the distance between the control and data planes is considerably small for benign traffic, we exploit this characteristic for detecting attacks as outliers. An adaptive thresholding scheme is implemented by adjusting the value of the threshold in accordance with the local statistics of the median absolute deviation (MAD) of the distances between the two planes. We demonstrate the efficacy of the proposed method for detecting DoS/DDoS attacks by analyzing traffic data obtained from publicly available datasets.     

Improved Multi-party Quantum Key Agreement with Four-qubit Cluster States

Quantum key agreement is a promising key establishing protocol that can play a significant role in securing 5G/6G communication networks. Recently, Liu et al. (Quantum Information Processing 18(8):1-10, 2019) proposed a multi-party quantum key agreement protocol based on four-qubit cluster states was proposed. The aim of their protocol is to agree on a shared secret key among multiple remote participants. Liu et al. employed four-qubit cluster states to be the quantum resources and the X operation to securely share a secret key. In addition, Liu et al.'s protocol guarantees that each participant makes an equal contribution to the final key. The authors also claimed that the proposed protocol is secure against participant attack and dishonest participants cannot generate the final shared key alone. However, we show here that Liu et al. protocol is insecure against a collusive attack, where dishonest participants can retrieve the private inputs of a trustworthy participant without being caught. Additionally, the corresponding modifications are presented to address these security flaws in Liu et al.'s protocol.     

Radiation shielding features for various tellurium-based alloys: a comparative study

We investigate the radiation shielding properties for four Te-based alloys. X-ray diffraction patterns revealed pure phases in all studied samples; however, a secondary phase is detected in the CrTe sample in good agreement with the literature. All samples’ densities were measured using the Archimedes principle. The mass attenuation coefficient (MAC) was calculated using Geant4 MC Toolkit and then compared with the XCOM data. Many photon-shielding properties were computed for all investigated samples based on the MAC. The Phy-X and SRIM were used to determine the fast neutron removal cross-section (Σ_R) and projected range, respectively. As a result, PbTe shows superior shielding features compared to the rest of the investigated samples to use this sample in different shielding applications.

     

Space partitioning in engineering design via metamodel acceptance score distribution

Metamodels for simulators are used to reduce computational costs in engineering system design. In general, metamodels have different fit accuracy levels over different regions in the design variables space, especially for highly nonlinear responses over wide spaces. A metamodeling strategy should place less emphasis on sub regions in the design variables space requiring relatively less complex metamodels. In this paper, we present a graphically based methodology that can be used to partition the space for piecewise metamodel building. The method is based on analyzing an initial global metamodel for acceptability in terms of prediction accuracy over the whole space; then generating acceptance score distribution (ASD) plots. Visual inspection of the ASD plots is used as a guidance to partition the design variables space, leading to a metamodel with fair prediction accuracy on a piece-by-piece basis, not just globally on average. The proposed methodology is general and can be applied to various metamodel types. It is tested on a number of problems, including some of the most highly nonlinear test problems used in the literature.

Rheological investigation of the influence of acrylate polymers on the modification of asphalt

The effect of ethylene, ethylene acrylate and glycidyl methacrylate (EA) terpolymer, and ethylene butyl acrylate (EBA) copolymer on asphalt modification was investigated at 4, 6 and 8% polymer concentrations. Both melt state rheology and asphalt concrete mix (ACM) were investigated. In the melt state analysis, dynamic shear rheology, storage stability, artificial ageing, and performance grading (PG) were studied. The PG grading of polymer modified asphalt (PMA) is correlated to the elastic properties of the polymers. Both resins improved the rheological properties, reduced the temperature susceptibility, showed better storage stability, and increase the upper grading (performance) temperature of the base asphalt. The two polymers showed similar ageing characteristics with little influence on flow activation energy. In asphalt concrete mix analysis, Marshall stability, stripping (durability), resilient modulus, and permanent deformation tests were performed. Polymer‐modified asphalt concrete mix (PMACM) has increased percent retained stability and the resilient modulus when compared with ACM. The elastic modulus of PMA and the resilient modulus of their ACM followed the same trend. Weak influence on water sensitivity was observed, but excellent rutting resistance was obtained for PMACM over ACM. EA (much cheaper than EBA) produced satisfactory properties of PMA and superior ACM properties when blended with the high asphaltenes Arabian asphalt. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3446–3456, 2006     

Electrospun highly corrosion-resistant polystyrene–nickel oxide superhydrophobic nanocomposite coating

A key challenge in producing superhydrophobic coatings (SHC) is to tailor the surface morphology on the micro-nanometer scale. In this work, a feasible and straightforward route was employed to manufacture polystyrene/nickel oxide (PSN) nanocomposite superhydrophobic coatings on aluminum alloys to mitigate their corrosion in a saline environment. Different techniques were employed to explore the influence of the addition of NiO nanoparticles to the as-prepared coatings. PSN-2 composite with?~?4.3 wt% of NiO exhibited the highest water contact angle (WCA) of 155°?±?2 and contact angle hysteresis (CAH) of 5°.

Graphic abstract

EIS Nyquist plots of 3 g of electrospun polystyrene coatings (a) without and with (b) 0.1, (c) 0.15, and (d) 0.2 g of NiO.