Although the use of polymeric additives has been widely accepted as a promising strategy to improve broad spectrum of pavement deficiencies, aging-induced mechanisms of polymer-modified asphalt binders and mixtures still have critical aspects that should be studied to a comprehensive extent. The primary objective of this paper is to advance the understanding of aging effect on the properties of polymer-modified asphalt binders and mixtures. In this study, six different polymeric products were of specific interest: styrene-butadiene-styrene (SBS), polypropylene (PP), styrene-acrylonitrile (SAN), high-density polyethylene (HDPE), polycarbonate (PC), and acrylonitrile-butadiene-styrene (ABS), each was applied at rates of 2% and 5% (by the wt. of asphalt binder) to prepare polymer-modified binders and mixtures. The prepared binders passed thin film oven test (TFOT), while the mixtures were subjected to normal and 16 h production aging. The compositional analysis of asphalt binders was discussed based on the elemental analysis tests while the penetration, ring and ball, and rotational viscosity tests were further studied to evaluate the physical properties. The asphalt mixtures were evaluated based on a series of engineering performance-based properties using indirect tensile strength (ITS), moisture susceptibility, uniaxial static creep-recovery, resilient modulus, and diametral fatigue tests. The fatigue tests were conducted without and with rest period so as to provide insight into the healing potential of different modified mixtures. The results showed that the aging increased the carbon component in all blends; however mixed results were attained regarding hydrogen, sulphur, and nitrogen. No obvious trends were ascertained for carbon, hydrogen, nitrogen, and sulphur due to polymer modification. Aging induced effects on polymer-modified binders and mixtures are highly dependent on the polymer type and modification level. Polymer modification had positive influence on ITS, creep strain and recovery ratio, resilient modulus, resistance to moisture damage, and fatigue life. Fatigue tests with rest period proved that the polymer-modified mixtures have higher tendency to heal compared to the unmodified mixtures, which resulted in an improvement in the fatigue performance of the mixtures. Except for the fatigue life, the aging of polymer-modified asphalt mixtures had no detrimental effect on the studied mechanistic properties.

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Air swirl motion inside the engine cylinder improves the air-fuel mixing which has a great effect on the thermal efficiency, soot formation, and engine emissions. In this work, experimental and numerical investigations were performed on a diesel engine cylinder having a configuration of a helical-spiral inlet port and shrouded valve under steady flow condition. Four shrouded valves having different shroud angles were used; the shroud angles are 90 deg, 120 deg, 150 deg, and 180 deg. With each shroud angle, four orientation angles were selected; they are 0 deg, 30 deg, 60 deg, and 90 deg. The experimental and numerical analyses were performed under a constant vacuum pressure of 350 mm H2O. In addition, numerical analysis, using the SST k − ω model, is performed on the engine cylinder using shrouded valve having shroud angle of 90 deg as a case study. The results showed that using of shrouded valve decreases the mass flow rate and the discharge coefficient while it increases the swirl number at all valve shroud and orientation angles except valve shroud of 180 deg and orientation angle of 90 deg. The numerical simulation analysis showed reasonable agreement with the experimental work. Therefore, the virtual test rig can be used for studying the influence of the valve and the port configurations on the flow characteristics.

Due to the Internet of Things (IoT) requirements for a high-density network with low-cost and low-power physical (PHY) layer design, the low-power budget transceiver systems have drawn momentous attention lately owing to their superior performance enhancement in both energy efficiency and hardware complexity reduction. As the power budget of the classical transceivers is envisioned by using inefficient linear power amplifiers (PAs) at the transmitter (TX) side and by applying high-resolution analog to digital converters (ADCs) at the receiver (RX) side, the transceiver architectures with low-cost PHY layer design (i.e., nonlinear PA at the TX and one-bit ADC at the RX) are mandated to cope with the vast IoT applications. Therefore, in this paper, we propose the orthogonal shaping pulses minimum shift keying (OSP-MSK) as a multiple-input multiple-output (MIMO) modulation/demodulation scheme in order to design the low-cost transceiver architectures associated with the IoT devices. The OSP-MSK fulfills a low-power budget by using constant envelope modulation (CEM) techniques at the TX side, and by applying a low-resolution one-bit ADC at the RX side. Furthermore, the OSP-MSK provides a higher spectral efficiency compared to the recently introduced MIMO-CEM with the one-bit ADC. In this context, the orthogonality between the in-phase and quadrature-phase components of the OSP are exploited to increase the number of transmitted bits per symbol (bps) without the need for extra bandwidth. The performance of the proposed scheme is investigated analytically and via Monte Carlo simulations. For the mathematical analysis, we derive closed-form expressions for assessing the average bit error rate (ABER) performance of the OSP-MSK modulation in conjunction with Rayleigh and Nakagami-m fading channels. Moreover, a closed-form expression for evaluating the power spectral density (PSD) of the proposed scheme is obtained as well. The simulation results corroborate the potency of the conducted analysis by revealing a high consistency with the obtained analytical formulas.

Space modulation techniques (SMTs) have emerged as promising candidates for spectral- and energy-efficient wireless communication systems since they strike a good balance among error performance, power efficiency, spectrum efficiency, and receiver complexity. In SMTs, the information is not only conveyed by the habitual M-ary signal constellations; rather, it is also conveyed by the indices of the transmit antennas. As such, the indices of the transmit antennas are harnessed in such a manner that enhances the transmission efficiency compared to the other multiple-input multiple-output (MIMO) opponents. Despite their exceptional advantages, SMTs suffer from a major drawback, which lies in the logarithmic proportion between their achievable data rates and the number of transmit antennas. In this regard, the fully-generalised spatial modulation (F-GSM) and the fully-quadrature spatial modulation (F-QSM) are proposed in this paper in order to vanquish this controversial drawback. In F-GSM and F-QSM, the transmit antennas used for data transmission are varied from the state in which only one transmit antenna is activated to the state in which multiple/all transmit antennas are activated. Therefore, a linear relationship between the achievable data rates and the number of transmit antennas is acquired. Moreover, a novel mathematical framework for assessing the average bit error rate (ABER) performance of the different SMTs is delineated. The driven mathematical framework is considered as the first major attempt to generalize the analytical analysis of different SMTs. In addition, the receiver’s computational complexity of the proposed schemes is obtained and analysed in terms of the computational complexity of different SMTs. The simulation results substantiate the validity of the analytical analysis conducted throughout the paper, as they are very akin to the obtained analytical formulas.

recently the indexed modulation (IM) technique in conjunction with the multi-carrier modulation gains an increasing attention. It conveys additional information on the subcarrier indices by activating specific subcarriers in the frequency domain besides the conventional amplitude-phase modulation of the activated subcarriers. Orthogonal frequency division multiplexing (OFDM) with IM (OFDM-IM) is deeply compared with the classical OFDM. It leads to an attractive trade-off between the spectral efficiency (SE) and the energy efficiency (EE). In this paper, the concept of the combinatorial modulation is introduced from a new point of view. The sparsity mapping is suggested intentionally to enable the compressive sensing (CS) concept in the data recovery process to provide further performance and EE enhancement without SE loss. Generating artificial data sparsity in the frequency domain along with naturally embedded channel sparsity in the time domain allows joint data recovery and channel estimation in a double sparsity framework. Based on simulation results, the performance of the proposed approach agrees with the predicted CS superiority even under low signal-to-noise ratio without channel coding. Moreover, the proposed sparsely indexed modulation system outperforms the conventional OFDM system and the OFDM-IM system in terms of error performance, peak-to-average power ratio (PAPR) and energy efficiency under the same spectral efficiency.

The increasing value of land and the limited availability of suitable sites for construction are greatly encouraging engineers to consider in situ improvement of weak soil deposits. To economically develop marginal sites a number of ground improvement techniques have been developed as stone columns, jet grouting, compaction grouting, short pile, dynamic compaction, lime stabilization etc. Stone column treatment is one of the most promising and favourable ground improvement techniques widely practiced all over the world. This paper presents a critical review of analytical, experimental, numerical and field studies on the aspect of ordinary and encased stone columns which have been published in the past three decades. Focus is on the recent advancement of encasing these columns with geosynthetic products to enhance their performance in load bearing capacity, decreasing the compressibility, accelerating and reducing the consolidation settlement. Another advantage of encasement is to prevent excessive bulging, squeezing of stone into soft soil. This paper presents installation methods, failure modes of stone columns and brief review of previous researches.

The increasing value of land and the limited availability of suitable sites for construction are greatly encouraging engineers to consider in situ improvement of weak soil deposits. To economically develop marginal sites a number of ground improvement techniques have been developed as stone columns, jet grouting, compaction grouting, short pile, dynamic compaction, lime stabilization etc. Stone column treatment is one of the most promising and favourable ground improvement techniques widely practiced all over the world. This paper presents a critical review of analytical, experimental, numerical and field studies on the aspect of ordinary and encased stone columns which have been published in the past three decades. Focus is on the recent advancement of encasing these columns with geosynthetic products to enhance their performance in load bearing capacity, decreasing the compressibility, accelerating and reducing the consolidation settlement. Another advantage of encasement is to prevent excessive bulging, squeezing of stone into soft soil. This paper presents installation methods, failure modes of stone columns and brief review of previous researches.

The increasing value of land and the limited availability of suitable sites for construction are greatly encouraging engineers to consider in situ improvement of weak soil deposits. To economically develop marginal sites a number of ground improvement techniques have been developed as stone columns, jet grouting, compaction grouting, short pile, dynamic compaction, lime stabilization etc. Stone column treatment is one of the most promising and favourable ground improvement techniques widely practiced all over the world. This paper presents a critical review of analytical, experimental, numerical and field studies on the aspect of ordinary and encased stone columns which have been published in the past three decades. Focus is on the recent advancement of encasing these columns with geosynthetic products to enhance their performance in load bearing capacity, decreasing the compressibility, accelerating and reducing the consolidation settlement. Another advantage of encasement is to prevent excessive bulging, squeezing of stone into soft soil. This paper presents installation methods, failure modes of stone columns and brief review of previous researches.

The increasing value of land and the limited availability of suitable sites for construction are greatly encouraging engineers to consider in situ improvement of weak soil deposits. To economically develop marginal sites a number of ground improvement techniques have been developed as stone columns, jet grouting, compaction grouting, short pile, dynamic compaction, lime stabilization etc. Stone column treatment is one of the most promising and favourable ground improvement techniques widely practiced all over the world. This paper presents a critical review of analytical, experimental, numerical and field studies on the aspect of ordinary and encased stone columns which have been published in the past three decades. Focus is on the recent advancement of encasing these columns with geosynthetic products to enhance their performance in load bearing capacity, decreasing the compressibility, accelerating and reducing the consolidation settlement. Another advantage of encasement is to prevent excessive bulging, squeezing of stone into soft soil. This paper presents installation methods, failure modes of stone columns and brief review of previous researches.