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This review covers the main examples of fuel-free light-driven micro/nanomotors and their different swimming styles, highlighting the most important parameters to consider when designing photocatalytic-based devices with a high propulsion efficiency.

Abstract This paper describes an accurate fault location algorithms based on two end measurements of voltage and current phasors for EHV transmission lines. The algorithm is implemented for plain, shunt and series compensated, transposed and untransposed transmission lines. The algorithm is free of source impedance variations and includes the effect of shunt capacitance. The effect on the accuracy of the algorithm due to point on wave of fault initiation, fault location on the line, fault type, variations of the fault resistance and errors due to signal processing, is investigated. The algorithm is found to be very accurate for plain and shunt compensated lines but needs further improvements to cater for series compensated lines.

Abstract One of the most recently important heat exchangers is the Printed circuit heat exchanger especially in the nuclear power plant and aerospace applications due to its very compact geometry and small print foot. This paper presents a 3D numerical investigation on the thermo-hydraulic performance of PCHE with new non-uniform channel design configuration. The new channel design is a rectangular cross section with repeated converging diverging sections or periodic diamond shape. The influence of three design parameters on the heat exchanger performance was studied and optimized, pitch length (p), length ratio (β) and the converging diverging angle (α). The computational models investigated in this study based on the operating conditions of the intermediate heat exchanger of very high temperature gas cooled reactor with helium as the working fluid under operating pressure of 3Mpa and inlet temperature of 800 K. The Reynolds number varied from 200 to 2000. Different Pitch lengths were used (1.59, 3.18, 6.36, and 12.73) mm, and different C-D angle (0, 4.5, 6, 7.5, 9, 10.5 and 12) and also different length ratios were used (0.2, 0.25 and 0.333). Three performance parameters were studied the Nusselt number, friction factor and the overall performance evaluation factor. Results show that the thermal performance enhanced with decreasing the pitch length and with increasing C-D angle and it was shown that this enhancement was found only at high Reynolds number above 1400. The best performance obtained at p=3.18, α=6 and β=0.25 based on the overall evaluation performance.

The current prevailing trend in design across key sectors prioritizes eco-design, emphasizing considerations of environmental aspects in the design process. The present work aims to take a significant leap forward by proposing a design process where sustainability serves as the primary driving force. In this context, sustainability is positioned as a fundamental component to be integrated into the initial stages of design, introducing innovative multidisciplinary criteria that redefine the design paradigm. Within this framework, sustainability is characterized using a comprehensive and quantifiable index encompassing technological, environmental, economic, and circular economy dimensions. To demonstrate the practical application of sustainability as the primary criterion in designing mechanical components, a parametrized finite element model of a composite plate is utilized, integrating both pristine and recycled fibers. Subsequently, a demonstrator derived from the aviation industry—specifically, a hat stiffener—is employed as a validation platform for the proposed methodology, ensuring alignment with the demonstrator’s specific requirements. Various representative trade-off scenarios are implemented to guide engineers’ decision-making during the conceptual design phase. Additionally, the robustness of the aforementioned methodology is thoroughly assessed concerning changes in the priority assigned to each sustainability criterion and its sensitivity to variations in the initial data. The significance of the proposed design methodology lies in its effectiveness in addressing the complex challenges presented by conflicting sustainability objectives. Furthermore, its adaptability positions it for potential application across various sectors, offering a transformative approach to sustainable engineering practices.

Exhaust thermal management (ETM) is crucial for effective emission mitigation in integrated exhaust aftertreatment systems of modern off-road diesel powertrains. However, conventional ETM strategies incur a significant fuel efficiency penalty. This study addresses the issue by investigating the application of variable valve actuation (VVA) for efficient ETM. For the first time, this investigation is conducted on a representative state-of-the-art off-road powertrain platform. It explores four VVA strategies with unprecedent level of rigour, employing a model-based approach that enables extended insights beyond stand-alone testing. Experiments with an EU Stage-V off-road diesel engine provide the baseline for validating a one-dimensional model in GT-Suite. A meticulously calibrated, predictive combustion model enables precise cross-evaluation of how VVA strategies affect exhaust gas temperature (EGT), efficiency, engine-out emissions and combustion characteristics, considering all trade-offs. VVA simulations are performed at three low-load operating points, where engine operation borders catalyst light-off temperature (LOT). The findings impartially confirm that cylinder deactivation (CDA) and intake modulation are the most promising VVA strategies for off-road engines, with EGT increments surpassing +250 °C and +150 °C respectively, accompanied by minor fuel penalties (up to +3.5 %). CDA demonstrated fuel savings of up to −2.5 % at certain points, due to reduced pumping and friction losses. Intake modulation displayed large reduction in engine-out NOx (>90 %) and minimal penalties in carbon emissions (HC, CO, and soot). The results underscore VVÁs potential as an efficient ETM option to help the next generation of off-road diesels to comply with upcoming EPA Tier 5 emission legislation.

We investigate the influence of thermoelectric effect on the onset of thermal instability in the Rayleigh-Bénard system with vertical magnetic field. An electrically conducting fluid is confined in an infinite horizontal layer between thick thermally and electrically conducting walls. A horizontal temperature variation resulting from convective instability leads to horizontal temperature gradients along the liquid-solid interface acting as a source of thermoelectric currents. Through interaction with the applied magnetic field, the Lorentz force is created modifying the instability. We find that the critical Rayleigh number for onset of convection is not changed by the thermoelectric effect. However, the thermal gradient on the liquid-solid boundary leads to a change of the shape of the unstable mode creating helical flow in the evolving convection rolls because of the Lorentz force parallel to their axis. The created kinetic helicity depends linearly on the dimensionless parameter K(TE) characterizing the strength of the thermoelectric effect.

Aim of study finding the best configuration among a set of system components. Power fluctuations and load disturbances in hybrid systems cause power inequality and system stability problems. Using hybrid energy storage systems is an effective solution in order to overcome unbalancing between power generating and load demands. In this paper, a methodology to perform the optimal sizing for Distributed Energy Resources (DERs) in three hybrid systems is developed, and reliability index is considered as a constraint. The optimum system configuration can meet the customer’s required Equivalent Loss Factor (ELF=0) with the minimum cost, and comparison cost between them. In these configurations, power generators are photovoltaic (PV)/wind turbine and three combination of battery bank and hydrogen tank is used as an energy storage system. Particle Swarm Optimization (PSO) algorithm has been used to optimize the cost function, and has been simulated in MATLAB for justification purpose.

In this work, a new strategy has been proposed where the waste paper, and their possible emissions are buried into the bricks to induce porosity and reduce the atmospheric pollution. The resulting porous bricks have been proved experimentally to have good durability, low density, low thermal conductivity and acceptable compressive strength comparing with the commonly used bricks. Different mixing percentages of a waste paper weight to wet clay have been tested, and a percentage of 1:10 seems to meet the usual standard for severe weather requirements. Many advantages have been achieved; enchantment the thermal insulation of the brick, increasing number of brick produced per ton of clay, reducing waste and their determinate effects, small reduction in the energy required to produce fired brick and producing homogeneous properties through the brick by properly initial mixing waste paper with wet clay. All these factors result in obtaining good brick characteristics with advantage of reducing waste. The procedures of measuring density, specific heat and thermal conductivity have been verified by obtaining experimental and theoretical values of thermal conductivity of the samples and good agreement has been observed.