Estimating the structures at high or low quantiles has become an important subject and attracted increasing attention across numerous fields. However, due to data sparsity at tails, it usually is a challenging task to obtain reliable estimation, especially for high-dimensional data. This paper suggests a flexible parametric structure to tails, and this enables us to conduct the estimation at quantile levels with rich observations and then to extrapolate the fitted structures to far tails. The proposed model depends on some quantile indices and hence is called the quantile index regression. Moreover, the composite quantile regression method is employed to obtain non-crossing quantile estimators, and this paper further establishes their theoretical properties, including asymptotic normality for the case with low-dimensional covariates and non-asymptotic error bounds for that with high-dimensional covariates. Simulation studies and an empirical example are presented to illustrate the usefulness of the new model.
Preventing filament tearing and fracture during high-efficiency 3D concrete printing remains a significant challenge, given their potential to compromise structural integrity and manufacturing efficiency. This study proposes a novel gravity-driven fresh-state tensile test, adapted from the “slug test”, for in-situ quality control of 3D-printed fiber-reinforced cementitious composites (FRCC). By analyzing the fracture response of extruded filaments, two quantitative indicators, fresh-state tensile strength (σfresh) and strain (εfresh), were established, potentially linking to the resistance against filament tearing during high-speed printing. The influences of processing method (casting vs. extrusion) and nozzle geometry (area, shape, and thickness) were investigated. Results show that optimizing nozzle geometry significantly enhanced filament integrity. Compared with casting, extrusion and further reducing nozzle area (380 to 150 mm2) and thickness (10 to 3 mm) increased fresh-state tensile strength by 62.1% (6.52 to 10.57 kPa) and strain by 60.7% (12.2% to 19.6%). These improvements effectively suppressed filament fracture during high-speed printing, increasing critical travel speed from 105.8 to 139.2 mm/s and reducing defect index from 0.16 to 0.02. The advantages established in the fresh state were ultimately preserved after hardening, yielding a 59.1% increase in ultimate tensile strength (to 9.45 MPa) and a 117.8% increase in strain (to 11.04%). The improvements might be attributed to enhanced fiber alignment (47.7° to 11.6°) induced by nozzle extrusion, which improves reinforcement efficiency, especially fresh-state resistance against filament fracture. This study establishes a potential link among fresh-state tensile response, printability, and hardened performance, providing an in-situ quality control protocol for 3D printing of FRCC.
Amid the global push for sustainable construction, bamboo has been widely studied as a rapidly renewable, high-performance building material. This paper reviews the published literature on bamboo’s journey from plant to structural component. The review first examines the fundamental botanical characteristics of bamboo, explaining the relationship between its hierarchical structure—from molecular to cellular levels—and its mechanical properties. It then transitions to an analysis of sustainable forestry, harvesting practices, the structural uses of round bamboo, and the manufacturing processes for engineered bamboo products, such as glued laminated bamboo and bamboo scrimber. Critical performance challenges are addressed by evaluating modern treatment methods that enhance durability, dimensional stability, and fire resistance. Structural applications are explored in detail, covering traditional building typologies, innovative connection systems, and the emerging potential for bamboo in mid- and high-rise as well as long-span structures. The life cycle perspective is completed by examining end-of-life scenarios, including reuse, recycling, and energy recovery. Ultimately, the review situates bamboo within the global context by examining resource distribution, trade, and the policy frameworks required to promote its widespread adoption. By consolidating research across multiple disciplines, this paper highlights the significant potential of bamboo to contribute to a low-carbon built environment. It concludes that a holistic, science-based approach is essential for overcoming remaining challenges and fully integrating this versatile material into modern construction practices.
The increasing integration of distributed energy resources (DERs) is crucial for power system decarbonization, yet unlocking DERs' flexibility is challenged by their inherent uncertainties and modelling complexity. As traditional optimization methods struggle with such uncertainty and complexity of DERs, reinforcement learning (RL) has emerged as a promising alternative for DER management. However, standard RL methods suffer from sample inefficiency and sub-optimality when trained from scratch. Inspired by the training paradigms in large language models, this paper proposes a Supervised Reinforcement Learning (SRL) framework for learning DER coordination policies. This framework first pre-trains a policy on demonstration data in a supervised-learning fashion, which is then further fine-tuned using RL. Furthermore, we propose a two-step fine-tuning process: offline fine-tuning for enhancing policy performance and online fine-tuning for adapting it to the real-world dynamics. Experiments demonstrate that RL implementations based on the proposed framework significantly outperform all benchmarks, achieving high cost efficiency even under low-quality demonstration data.
Biomass pretreatment represents a key step for overcoming structural recalcitrance and enhancing saccharification towards biofuel and bioenergy production, but is currently limited by high-cost and non-recyclable material streams. This study presents a full-chain strategy that couples biomass pretreatment, enzymatic hydrolysis and microbial fermentation to produce sugars and value-added lipids, so as to maximise resource efficiency. Crude glycerol, a biodiesel byproduct, was employed not only as a pretreatment medium but also as an integral component in downstream co-valorisation. Microwave pretreatment of sugarcane bagassein crude glycerol enabled a remarkable lignin removal from 29.2% to 15.3% and boosted subsequent enzymatic glucose yield from 7.8% to 75.7%. Moreover, glycerol recovered from the pretreatment liquor served as an effective fermentable carbon source, enabling a lipid yield of 3.7 g/L byCryptococcus curvatus, which significantly outperformed pure glycerol. This work establishes an integrated framework to synergisticallyconvert two types of agro-wastes into multiple products for high-efficiency and low-cost biorefineries.
