A novel intelligent adaptive control of laser-based ground thermal test

AbstractLaser heating technology is a type of potential and attractive space heat flux simulation technology, which is characterized by high heating rate, controlled spatial intensity distribution and rapid response. However, the controlled plant is nonlinear, time-varying and uncertainty when implementing the laser-based heat flux simulation. In this paper, a novel intelligent adaptive controller based on proportion–integration–differentiation (PID) type fuzzy logic is proposed to improve the performance of laser-based ground thermal test. The temperature range of thermal cycles is more than 200K in many instances. In order to improve the adaptability of controller, output scaling factors are real time adjusted while the thermal test is underway. The initial values of scaling factors are optimized using a stochastic hybrid particle swarm optimization (H-PSO) algorithm. A validating system has been established in the laboratory. The performance of the proposed controller is evaluated through extensive experiments under different operating conditions (reference and load disturbance). The results show that the proposed adaptive controller performs remarkably better compared to the conventional PID (PID) controller and the conventional PID type fuzzy (F-PID) controller considering performance indicators of overshoot, settling time and steady state error for laser-based ground thermal test. It is a reliable tool for effective temperature control of laser-based ground thermal test

Mitigating catalyst deactivation in selective hydrogenation by enhancing dispersion and utilizing reaction heat effect

ACKNOWLEDGMENT This work was financially supported by National Key R&D Program of China (2021YFB3801600), National Natural Science Foundation of China (21908002), and Fundamental Research Funds for the Central Universities (buctrc201921, JD2223).Peer reviewedPostprin

Comparison of IUCN and species distribution modeling-estimated ranges of shorebirds in Coastal Mainland China

Large areas of unsuitable habitat are often included within the extent of occurrence (EOO) of species, such as the EOO defined by the IUCN (EOOiucn), because the techniques used to estimate the EOO of species often depend on topological methods that do not account for ranges of environmentally suitable habitat. Assessments of the EOO of species are important because they are used in conservation status evaluations. We generated species distribution models in MaxEnt using citizen science data for 8 shorebird species inhabiting China’s coasts from multiple open data sources along with environmental variables to estimate the EOO of these species (EOOm). We then compared EOOm and EOOiucn and assessed the conservation status of these species according to the distribution of national nature reserves. EOOm was generally smaller than EOOiucn for the 8 shorebird species. Over 80 % of the EOOm of the 8 shorebird species did not fall within any national nature reserves, revealing large conservation gaps. Some of unprotected EOOm of these species overlaps with high human footprint area, especially in the Bohai Bay and the Jiangsu–Shanghai coastal region. Our results highlight the need for strengthened conservation effort for unprotected EOOm showing little overlap with national nature reserves, especially in the Bohai Bay and Jiangsu–Shanghai coastal regions

Suitable Habitat Dynamics of Wintering Geese in a Large Floodplain Wetland: Insights from Flood Duration

The relationship between hydrological variation and the habitat use of waterbirds in wetland complexes is a significant field of ecological research. Quantification of the relationships between wetland hydrological attributes and waterbirds distribution is critical for the success of waterbird conservation. In this study, flood duration (FD) derived from synthetic aperture radar (SAR) imagery was combined with geese GPS tracking data to quantify the optimal FD thresholds for identifying geese habitats. Based on the thresholds, we defined the suitable habitats of wintering geese and investigated the difference in the spatial distribution pattern of habitat from 2018 to 2020 in Poyang Lake, China. We also considered the role of sub-lakes in habitat protection. The results showed that the area of suitable habitats for wintering geese decreased in both dry and wet years, and the range of optimal FD threshold was wider in normal years than in both dry and wet years. The proportion of suitable habitats per unit area was greater in the sub-lakes than in the whole Poyang Lake. We concluded that FD indices extracted from SAR data are valuable for reflecting the influence of the pattern of hydrological variation on waterbird distribution and for the protection and rational use of wetland ecosystems

It takes two to Tango: Plant height and nutrient level determine the diet selection of wintering geese in Poyang Lake, a Ramsar wetland

In Poyang Lake, the largest and one of the most important wintering sites in the East Asian-Australasian Flyway, Carex (Carex cinerascens Kük) meadows provide the primary food source for the wintering geese. However, due to intensified river regulation and more frequent extreme climatic events such as drought, observational evidence suggests that the synchrony of geese migration and Carex phenology could not be maintained without human interventions, imposing a great risk of food shortage during the wintering period. Consequently, the current conservation priority in this Ramsar site is shifted to wet meadow improvement to ensure optimal food quality. Understanding the food preferences of wintering geese is the key for effective wet meadow management. As the growth stage and nutrient level of food plants are the decisive factors influencing the diet selection of herbivores, in this study, we sampled the preferred food items by tracking the foraging paths of the Greater White-fronted Goose (n = 84) and Bean Goose (n = 34) to quantify the “foraging window” in terms of plant height,protein level, and energy content. Further, we established relationships between the above three variables of Carex based on in-situ measurements. The results show that the geese prefer plants with height ranging from 2.4 to 25.0 cm, with protein content from 13.9 to 25.2 %, and energy content from 1440.0 to 1813.6 KJ/100 g. While plant energy content increases with height, the height-protein level relationship is negative. The opposite growth curves signify a conservation challenge to maintain the delicate balance between the quantity and quality requirements of wintering geese. Carex meadow management, such as mowing, should focus on optimizing the timing of action to maximize energy supply while maintaining the right protein level for the long-term fitness, reproduction and survival of the birds

Investigation of thermal dynamics for different leading configuration in hybrid laser-MIG welding

For hybrid laser-MIG welding of aluminum alloy, the weld bead quality is decided by the thermal dynamics in the molten pool. In order to analyze the influence of leading configuration on thermal behavior and mass transfer, a three-dimensional numerical model is established. In the model, a combined model is utilized to simulate the multiple reflections and Fresnel absorption of laser beam. The laser-arc interaction is considered and the plasma is shrinked for arc-leading configuration. Surface tension, electromagnetic force, buoyancy are considered to investigate the fluid flow pattern, and droplet impact and arc pressure are taken into account to track the free surface. For different configurations, the temperature and velocity field, together with concentration distribution of magnesium and zinc are compared and analyzed. The results show that transport phenomena of the molten pool is strongly affected by the configuration. For arc-leading (AL) configuration, it is easier to get a larger penetration. Meanwhile, the concentration distribution of magnesium and zinc is more homogeneous for laser-leading (LL) configuration. Furthermore, the developed model can provide theoretical basis for processing experiments

Collaboratively enhancing the strength and ductility of GH3600 Nickel-Based Ultra-Thin strips via the Pre-Precipitation process

Here, the effects of pre-precipitation annealing on the microstructural evolution and room-temperature mechanical properties of nickel-based ultra-thin strips after the subsequent high-temperature annealing were analyzed. By pre-precipitation annealing, discontinuous grain-boundary carbide was introduced into the cold-rolled 67 μm GH3600 nickel-based ultra-thin strips, which hindered the rapid migration of grain boundaries. Thus, the grain size was maintained at only 5.5 μm after holding at 1050 °C for 1 h, indicating that the high-temperature microstructure stability of the strips was significantly improved. Further, the phenomenon of local single-layer crystal and size effect caused by the abnormal coarsened grains, which were more than 100 μm in size during the single-stage high-temperature annealing (1050 °C for 1 h), was eliminated. Owing to the weakened free surface influence and an increase in the strengthening effect, such as grain boundary strengthening, as well as intragranular and intergranular back stress strengthening, the work hardening ability of the strips was enhanced after pre-precipitation annealing, thereby resulting in excellent comprehensive mechanical properties whose flow stress and elongation were 1.9 and 4.8 times those of single-stage high-temperature annealing. This study successfully provides an economical and easy-to-implement effective method to prepare solid-solution-strengthened high-performance ultra-thin superalloy strips

Conservation and restoration efforts have promoted increases in shorebird populations and the area and quality of their habitat in the Yellow River Delta, China

Conservation policies have been formulated for coastal wetlands in China, and exploration of conservation effectiveness based on waterbirds and their habitat is important for guiding conservation actions. We characterized the effects of conservation efforts on shorebird diversity, habitat area and quality using long-term remote sensing data, and shorebird survey data in the Yellow River Delta. From 1997 to 2021, habitat area, quality and population number significantly declined by 49.8% (r = −0.72, p p 2 = 0.77, p p > 0.05, slope = −0.25), quality (decreased by 10.53%, r = −0.68, p > 0.05, slope = −0.008), and population size (significantly decreased by 94.5%, r = −0.95, p p p > 0.05, slope = 0.12), quality (increased by 17.12%, r = 0.83, p > 0.05, slope = 0.01), and population size (increased by 8.34%, R2 = 0.29, p > 0.05) slightly increased. The coefficients of variation for habitat area and quality, and population size were smaller after 2012 than before 2012. These results suggest that conservation actions maintained the stability of waterbird populations and their habitat; additional actions are needed to mediate the conservation of other degraded habitats along coastal wetlands.</p

Using citizen science data to inform the relative sensitivity of waterbirds to natural versus human-dominated landscapes in China

Habitat loss is widely regarded as one of the most destructive factors threatening native biodiversity. Because migratory waterbirds include some of the most globally endangered species, information on their sensitivity to landscape would benefit their conservation. While citizen science data on waterbird species occurrence are subjected to various biases, their appropriate interpretation can provide information of benefit to species conservation. We apply a bootstrapping procedure to citizen science data to reduce sampling biases and report the relative sensitivity of waterbird species to natural versus human-dominated landscapes. Analyses are performed on 30,491 data records for 69 waterbird species referred to five functional groups observed in China between 2000 and 2018. Of these taxa, 30 species (43.5%) are significantly associated with natural landscapes, more so for cranes, geese, and ducks than for shorebirds and herons. The relationship between land association and the threat status of waterbirds is significant when the range size of species is considered as the mediator, and the higher the land association, the higher the threat status. Sensitive species significantly associated with natural landscapes are eight times more likely to be classified as National Protected Species (NPS) Classes I or II than less sensitive species significantly associated with human-dominated landscapes. We demonstrate the potential for citizen science data to assist in conservation planning in the context of landscape changes. Our methods might assist others to obtain information to help relieve species decline and extinction