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Within the domain of municipal solid waste (MSW) management, incineration is recognized as an efficient volume reduction method, yet it produces substantial quantities of bottom ash (IBA). Redirecting IBA into cementitious frameworks is challenging due to diminished workability, mechanical properties, and durability. This study investigates alumina micro powder (ALMP)'s effect on improving the mechanical and durability aspects of ecological ultra-high performance concrete (EUHPC) produced with IBA. The research examines ALMP's role at various doping levels on the EUHPC's rheological properties, mechanical strengths, durability indices, ultrasonic pulse velocity (UPV), and elastic modulus. Additionally, nanoindentation tests discern ALMP's reinforcing effect on EUHPC's stiffness. Summarizing key findings: ALMP significantly enhances EUHPC's flexural and compressive strengths, with increases ranging from 6.98 % to 24.87 % and 12.39–20.81 %, respectively. Moreover, ALMP raises the elastic modulus by 6.05–19.07% and UPV by 3.11–7.18 %, reflecting a denser, more compact matrix structure. Durability enhancements are evidenced by reductions in drying shrinkage by 4.41–20.01 % and decreased chloride migration by 7.01–22.14 %. Nanoindentation reveals a densification in the microstructure, with escalated high-density C-S-H phases and reduced low-density C-S-H and unhydrated materials. IBA replacement yields energy savings of 11.43 %, CO 2 emission reduction of 7.01 %, and cost savings of 1.18 %. The optimal ALMP inclusion is identified at 10 %, balancing workability, mechanical and microstructural benefits in EUHPC. These revelations position IBA as a useful component in the concrete sector and advocate for ALMP as a beneficial adjunct to elevate the performance of IBA-based concrete towards sustainable development goals. • Mixture of eco-UHPC was designed via MAA particle packing model. • Properties of eco-UHPC were improved via Al 2 O 3 micro-powder. • Optimal content of Al 2 O 3 micro-powder in eco-UHPC was 10%. • Al 2 O 3 micro-powder contributed to a denser microstructure of eco-UHPC. • Environmental friendliness of eco-UHPC was improved via Al 2 O 3 micro-powder. [ABSTRACT FROM AUTHOR]

This study aims to explore the dynamic response of ultra-high performance engineered cementitious composites (UHP-ECC) incorporating waste crumb rubber (CR) at various temperatures, focusing on its potential to enhance the resilience and sustainability of civil infrastructures against low-velocity impacts. To date, the impact behaviour of UHP-ECC under low temperatures has rarely been explored. Firstly, natural river sand and waste tyre CR was utilized to prepare the UHP-ECC. Then, a series of mechanical tests, including compression test, flexural test and uniaxial tensile test were carried out to investigate the static mechanical properties of rubberised UHP-ECCs. In addition, the effects of different waste CR incorporations (0%, 5%, 10%, and 15%) and various temperatures (25 °C, −5 °C, −30 °C, −50 °C, −100 °C and −196 °C) were comprehensively investigated by low-velocity impact tests with constant impact energy. Lastly, the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) model was introduced to evaluate the overall performance of UHP-ECC. It was found that the use of river sand and CR significantly enhanced the tensile ductility and impact toughness of UHP-ECC. Impact energy primarily dissipates through damage such as matrix crack initiation, propagation, and fibre pull-out/rupture within the specimen. Adding CR notably decreased stress fluctuations during impact at room temperature, facilitating steady state energy absorption. Moreover, the time to reach peak impact force decreased with decreasing temperature across all UHP-ECC groups. At room temperature during impact process, fibre failure mode is dominated by pull-out failure, while lower temperatures lead to increased fibre rupture at the cracking surface. In low-temperature conditions, the impact response of rubberised UHP-ECC necessitates a comprehensive consideration of the synergistic effects, including material contraction, fibre bridging capacity, rubber phase transition, and water freezing. [ABSTRACT FROM AUTHOR]

As a kind of space robot, the two-arm cascade combination system (TACCS) has been applied to perform auxiliary operations at different locations outside space cabins. The motion coupling relation of two arms and complex surrounding obstacles make the collision-free trajectory planning optimization of TACCS more difficult, which has become an urgent problem to be solved. For the above problem, this paper proposed collision-free and time–energy–minimum trajectory planning optimization algorithms, considering the motion coupling of two arms. In this method, the screw-based inverse kinematics (IK) model of TACCS is established to provide the basis for the motion planning in joint space by decoupling the whole IK problem into two IK sub-problems of two arms; the minimum distance calculation model is established based on the hybrid geometric enveloping way and basic distance functions, which can provide the efficient and accurate data basis for the obstacle-avoidance constraint condition of the trajectory optimization. Moreover, the single and bi-layer optimization algorithms are presented by taking motion time and energy consumption as objectives and considering obstacle-avoidance and kinematics constraints. Finally, through example cases, the results indicate that the bi-layer optimization has higher convergence efficiency under the premise of ensuring the optimization effect by separating variables and constraint terms. This work can provide theoretical and methodological support for the efficient and intelligent applications of TACCS in the space arena. [ABSTRACT FROM AUTHOR]

For complex equipment, it is easy to over-evaluate the impact of failure on production by estimating the reliability level only through failure probability. To remedy this problem, this paper proposes a statistical evaluation method based on fuzzy failure data considering the multi-state characteristics of equipment failures. In this method, the new reliability-evaluation scheme is firstly presented based on the traditional statistical analysis method using the Weibull distribution function. For this scheme, the failure-grade index is defined, and a fuzzy-evaluation method is also proposed by comprehensively considering failure severity, failure maintenance, time, and cost; this is then combined with the time between failures to characterize the failure state. Based on the fuzzy failure data, an improved adaptive-failure small-sample-expansion method is proposed based on the classical bootstrap method and the deviation judgment between distributions of the original and newborn samples. Finally, a novel reliability-evaluation model, related to the failure grade and its membership degree, is established to quantify the reliability level of equipment more realistically. Example cases for three methods of the scheme (the failure-grade fuzzy-evaluation method, the sample-expansion method, and the reliability-evaluation modeling method) are presented, respectively, to validate the effectiveness and significance of the proposed reliability-evaluation technology. [ABSTRACT FROM AUTHOR]