Search Results (18,396)

The K-means algorithm utilizes the Euclidean distance metric to quantify the similarity between data points and clusters, with the fundamental objective of assessing the relationship between points. It is important to note that, during the process of clustering, the relationships between the remaining points in the cluster and the points to be measured are ignored. In consideration of the aforementioned issues, this paper proposes the utilization of extension distance for the purpose of evaluating the relationship between the points to be measured and the cluster classes. Furthermore, it introduces a variant of the K-means algorithm based on the separator distance. Through a series of comparative experiments, the effectiveness of the proposed algorithm for clustering fan-shaped datasets is preliminarily verified. Full article

The present study evaluated the effect of adding 0% (control), 30%, 40% and 50% SPMs (small-peptide chelating trace minerals) to replace ITMs (inorganic trace minerals) in the diets of Litopenaeus vannamei; 720 shrimp were randomly assigned to four treatments (six replicates per group, 30 shrimp per replicate) in a 42-day feeding trial. There were no significant differences (p > 0.05) among the control, 40% SPM and 50% SPM groups in terms of the survival rate, weight gain rate, specific growth rate, hepatosomatic index, condition factor, feed intake, feed conversion ratio, or protein efficiency ratio; however, protein efficiency ratio was reduced in the 30% SPM group (p < 0.05). Glucose, triglyceride, and aspartate aminotransferase levels in the hemolymph of the 30% SPM group were significantly increased (p < 0.05), while the glucose and aspartate aminotransferase levels were also significantly increased in the 40% SPM group (p < 0.05). In the 50% SPM group, the glucose and triglyceride levels were also significantly increased (p < 0.05). Hepatopancreatic alkaline phosphatase activity was elevated at 40% SPM, and alkaline phosphatase, acid phosphatase, glutathione peroxidase, and total antioxidant capacity activities were significantly increased in the 50% SPM group (p < 0.05). The moisture content and drip loss were reduced in both the 40% and 50% SPM groups (p < 0.05). Therefore, replacing 40–50% ITMs with SPMs can maintain growth performance while enhancing physiological functions. In conclusion, the results of this study demonstrate that the incorporation of 30–50% SPMs into one’s diet constitutes a viable alternative to 100% ITMs. Full article

Prime editing (PE) has emerged as a transformative genome editing technology, enabling precise base substitutions, insertions, and deletions without inducing double-strand DNA breaks (DSBs). However, its application in zebrafish remains limited by low efficiency. Here, we leveraged PE7, a state-of-the-art PE system, combined with La-accessible prime editing guide RNAs (pegRNAs), to enhance editing efficiency in zebrafish. By co-incubating PE7 protein with La-accessible pegRNAs to form ribonucleoprotein (RNP) complexes and microinjecting these complexes into zebrafish embryos, we achieved up to 15.99% editing efficiency at target loci—an improvement of 6.81- to 11.46-fold over PE2. Additionally, we observed 16.60% 6 bp insertions and 13.18% 10 bp deletions at the adgrf3b locus, representing a 3.13-fold increase over PE2. Finally, we used PE to introduce desired edits at the tyr locus, successfully generating zebrafish with the tyr P302L mutation that exhibited melanin reduction. These findings demonstrate that PE7 significantly enhances prime editing efficiency in fish, providing novel tools for functional gene studies and genetic breeding in aquatic species. Full article

Under the rapid development of the digital economy, the interactive relationship between exports and the digital economy has become an important issue for promoting regional economic growth. Based on the panel data of 31 provinces and municipalities in China from 2012 to 2022, this paper systematically examines the impact of exports on economic growth and the moderating role of the digital economy, and it introduces research and development (R&D) investment to test its mediating mechanism. The research finds that exports significantly promote regional economic growth. The digital economy has a negative moderating effect on the export growth effect, and it is significant in the eastern region but not significant in the central and western regions, showing obvious regional heterogeneity. R&D investment has played a partial mediating role between exports and economic growth. This paper suggests that the government should focus on regional differences, promote the deep integration of the digital economy and exports, enhance technological innovation capabilities, formulate differentiated policies based on local conditions, strengthen the construction of digital infrastructure, optimize the export structure, support the development of R&D-driven enterprises, and build a digital export system that promotes regional coordination and high-quality growth, so as to achieve high-quality coordinated sustainable regional development. This paper also has certain reference value for other developing economies, in promoting the integration of the digital economy and trade. Full article

To accurately assess the effect of different plate thicknesses on the residual stress field of laser shock peened GH3039 superalloy, residual stress measurements were performed on GH3039 alloy plates with thicknesses of 2 mm and 5 mm after laser shock peening (LSP) treatment. Both quasi-static and high strain rate mechanical tests of GH3039 were conducted, and the Johnson-Cook (J-C) constitutive equation for GH3039 alloy at specific strain rates was fitted based on the experimental results. To obtain the parameter C in the J-C constitutive equation of GH3039 alloy under ultra-high strain rates, a modified method was proposed based on LSP experiment and finite element simulation results. Using the modified GH3039 alloy J-C constitutive equation, numerical simulations and comparative analyses of the residual stress field of GH3039 alloy plates of different thicknesses under LSP were carried out using ABAQUS software. The simulated residual stress fields of laser-shocked GH3039 alloy plates of different thicknesses were in good agreement with the experimental measurements, indicating that the modified GH3039 alloy J-C constitutive equation can accurately predict the mechanical behavior of GH3039 alloy under ultra-high strain rates. Based on the modified GH3039 alloy J-C constitutive equation, the effect of different plate thicknesses on the residual stress distribution of laser-shocked GH3039 alloy was studied, along with the underlying mechanisms. The unique distribution characteristics of residual stresses in laser-shocked GH3039 plates with varying thicknesses are primarily attributed to differences in plate bending stiffness and the detrimental coupling effects of reflected tensile waves. Full article

Sulfur fumigation (SF), acid dipping (HCl treatment, HAT), and their combination (SF+HAT) are common methods for long-term preservation and color protection of litchi. However, their effects on the metabolic profile of the litchi pericarp have not been investigated. SF resulted in a yellowish-green pericarp by up-regulating lightness (L*), b*, C*, and h° but down-regulating total anthocyanin content (TAC) and a*, while HAT resulted in a reddish coloration by up-regulating a*, b*, and C* but down-regulating L*, h°, and TAC. SF+HAT recovered reddish color with similar L*, C* to SF but a*, b*, h°, and TAC between SF and HAT. Differential accumulated metabolites (DAMs) detected in HAT (vs. control) were more than those in SF (vs. control), but similar to those in SF+HAT (vs. control). SF specifically down-regulated the content of cyanidin-3-O-rutinoside, sinapinaldehyde, salicylic acid, and tyrosol, but up-regulated 6 flavonoids (luteolin, kaempferol-3-O-(6″-malonyl)galactoside, hesperetin-7-O-glucoside, etc.). Five pathways (biosynthesis of phenylpropanoids, flavonoid biosynthesis, biosynthesis of secondary metabolites, glutathione metabolism, and cysteine and methionine metabolism) were commonly enriched among the three treatments, which significantly up-regulated sulfur-containing metabolites (mainly glutathione, methionine, and homocystine) and down-regulated substrates for browning (mainly procyanidin B2, C1, and coniferyl alcohol). These results provide metabolic evidence for the effect of three treatments on coloration and storability of litchi. Full article

In recent years, various devices utilizing surface acoustic waves (SAW) have emerged as powerful tools for manipulating particles and fluids in microchannels. Although they demonstrate a wide range of functionalities across diverse applications, existing devices still face limitations in flexibility, manipulation efficiency, and spatial resolution. In this study, we developed a dual-sided standing surface acoustic wave (SSAW) device that simultaneously excites acoustic waves through two piezoelectric substrates positioned at the top and bottom of a microchannel. By fully exploiting the degrees of freedom offered by two pairs of interdigital transducers (IDTs) on each substrate, the system enables highly flexible control of microparticles. To explore its capability on particle aggregation, we developed a two-dimensional numerical model to investigate the influence of the SAW phase modulation on the established acoustic fields within the microchannel. Single-particle motion was first examined under the influence of the phase-modulated acoustic fields to form a reference for identifying effective phase modulation strategies. Key parameters, such as the phase changes and the duration of each phase modulation step, were determined to maximize the lateral motion while minimizing undesired vertical motion of the particle. Our dual-sided SSAW configuration, combined with novel dynamic phase modulation strategy, leads to rapid and precise aggregation of microparticles towards a single focal point. This study sheds new light on the design of acoustofluidic devices for efficient spatiotemporal particle concentration. Full article

The coastal sandy land in northeast Hainan Province is typical for this land type, also exhibiting strong sand activity. This study is based on wind speed, wind direction, and sediment transport data obtained at a field meteorological station using an omnidirectional sand accumulation instrument from 2020 to 2024, studying the coastal aeolian environment and sediment transport distribution characteristics in the region. Its findings provide a theoretical basis for comprehensively analyzing the evolution of coastal aeolian landforms and the evaluation and control of coastal aeolian hazards. The research results show the following: (1) The annual average threshold wind velocity for sand movement in the study area is 6.84 m/s, and the wind speed frequency (frequency of occurrence) is 51.54%, dominated by easterly (NE, ENE) and southerly (S, SSE) winds. (2) The drift potential (DP) refers to the potential amount of sediment transported within a certain time and spatial range, and the annual drift potential (DP) and resultant drift potential (RDP) of Mulan Bay from 2020 to 2024 were 550.82 VU and 326.88 VU, respectively, indicating a high-energy wind environment. The yearly directional wind variability index (RDP/DP) was 0.59, classified as a medium ratio and indicating blunt bimodal wind conditions. The yearly resultant drift direction (RDD) was 249.45°, corresponding to a WSW direction, indicating that the sand in Mulan Bay is generally transported in the southwest direction. (3) When the measured data extracted from the sand accumulation instrument in the study area from 2020 to 2024 were used for statistical analysis, the results showed that the total sediment transport rate (the annual sediment transport of the observation section) in the study area was 110.87 kg/m·a, with the maximum sediment transport rate in the NE direction being 29.26 kg/m·a. These results suggest that when sand fixation systems are constructed for relevant infrastructure in the region, the construction direction of protective forests and other engineering measures should be perpendicular to the net direction of sand transport. Full article

Internet of Things (IoT)-based solar insecticidal lamps (SIL-IoTs) offer an eco-friendly alternative by merging solar energy harvesting with intelligent sensing, advancing sustainable smart agriculture. However, SIL-IoTs encounter practical challenges, e.g., hardware aging, electromagnetic interference, and abnormal data patterns. Therefore, developing an effective fault detection and diagnosis (FDD) system is essential. In this survey, we systematically identify and address the core challenges of implementing FDD of SIL-IoTs. Firstly, the fuzzy boundaries of sample features lead to complex feature interactions that increase the difficulty of accurate FDD. Secondly, the category imbalance in the fault samples limits the generalizability of the FDD models. Thirdly, models trained on single scenarios struggle to adapt to diverse and dynamic field conditions. To overcome these challenges, we propose a multi-level solution by discussing and merging existing FDD methods: (1) a data augmentation strategy can be adopted to improve model performance on small-sample datasets; (2) federated learning (FL) can be employed to enhance adaptability to heterogeneous environments, while transfer learning (TL) addresses data scarcity; and (3) deep learning techniques can be used to reduce dependence on labeled data; these methods provide a robust framework for intelligent and adaptive FDD of SIL-IoTs, supporting long-term reliability of IoT devices in smart agriculture. Full article

In this paper, an image-based visual control scheme is proposed for a quadrotor aerial vehicle with unknown mass and moment of inertia. In order to reduce the impacts of underactuation in quadrotor dynamics, a virtual image plane is introduced and appropriate image moment features are defined to decouple the image features from the movement of the vehicle. Subsequently, based on the quadrotor dynamics, a backstepping method is used to construct the torque controller, ensuring that the control system has superior dynamic performance. Furthermore, an adaptive control scheme is then designed to enable online estimation of dynamic parameters. Finally, stability is formally verified through constructive Lyapunov methods, and performance test results validate the efficacy and robustness of the proposed control scheme. It can be verified through performance tests that the quadrotor successfully positions itself at the desired position under uncertain dynamic parameters, and the attitude angles converge to the expected values. Full article

The interaction between bacteria and fungi is one of the key interactions of microbial ecology, including mutualism, antagonism, and competition, which profoundly affects the balance and functions of animal microbial ecosystems. This article reviews the interactive dynamics of bacteria and fungi in more concerned microenvironments in animals, such as gut, rumen, and skin. Moreover, we summarize the molecular mechanisms and ecological functions of the interaction between bacteria and fungi. Three major bacterial–fungal interactions (mutualism, antagonism, and competition) are deeply discussed. Understanding of the interactions between bacteria and fungi allows us to understand, modulate, and maintain the community structure and functions. Furthermore, this summarization will provide a comprehensive perspective on animal production and veterinary medicine, as well as guide future research directions. Full article

Photovoltaic–thermal (PVT) technology has attracted considerable attention for its ability to significantly improve solar energy conversion efficiency by simultaneously providing electricity and heat during the day. PVT technology serves a purpose in condensers and subcoolers for passive cooling in refrigeration systems at night. In our previous work, we proposed a switchable film-insulated photovoltaic–thermal–passive cooling (PVT-PC) module to address the structural incompatibility between diurnal and nocturnal modes. However, the performance of the proposed module strongly depends on two key design parameters: the structural height and the vacuum level of the air cushion. In this study, a numerical model of the proposed module is developed to examine the impact of design and meteorological parameters on its all-day performance. The results show that diurnal performance remains stable across different structural heights, while nocturnal passive cooling power shows strong dependence on vacuum level and structural height, achieving up to 103.73 W/m² at 10 mm height and 1500 Pa vacuum, which is comparable to unglazed PVT modules. Convective heat transfer enhancement, induced by changes in air cushion shape, is identified as the primary contributor to improved nocturnal cooling performance. Wind speed has minimal impact on electrical output but significantly enhances thermal efficiency and nocturnal convective cooling power, with a passive cooling power increase of up to 31.61%. In contrast, higher sky temperatures degrade nocturnal cooling performance due to diminished radiative exchange, despite improving diurnal thermal efficiency. These findings provide fundamental insights for optimizing the structural design and operational strategies of PVT-PC systems under varying environmental conditions. Full article

With the rapid growth of elevator installations, conventional scheduled maintenance struggles to meet the dual demands of ensuring operational safety and cost control. This study proposes an innovative on-demand maintenance method that aligns with the Chinese policy directives on elevator maintenance reform. First, we conduct a historical fault cause analysis to identify the root causes of elevator entrapment incidents. Next, we establish an entrapment prediction model based on our historical data. Then, we design an elevator entrapment risk index report according to the prediction results. Finally, we formulate an on-demand maintenance plan that combines insights from the report with the conclusions of the cause analysis. Field implementation and comparative experiments demonstrate that the proposed on-demand maintenance method outperforms the scheduled one. The result shows significant reductions in accident and maintenance workload, justifying the practical value of this approach for the industry. Full article

Siniperca chuatsi is an important high-quality freshwater aquaculture species in China. In nature, it feeds exclusively on live food. In this study, domesticated juvenile S. chuatsi were divided into three groups and fed live food (group L), compound feed (group C), or a mixed diet (group M) for three months to investigate the molecular mechanisms underlying adaptation to compound feed. Histopathological examination revealed that compound feed consumption induced looser liver cell arrangement, hepatocyte morphological irregularities, and vacuolization. A total of 1033 and 1428 differentially expressed genes (DEGs), and 187 and 184 differential metabolites (DMs), were identified in the C vs. L and C vs. M groups, respectively. Transcriptomic analysis revealed that the significantly and commonly enriched metabolic pathways shared by both comparison groups were predominantly involved in amino acid, carbohydrate, and lipid metabolisms. Metabolomic analysis demonstrated that the significantly and commonly enriched metabolic pathways shared by both comparison groups were the arachidonic acid metabolism, linoleic acid metabolism, oxidative phosphorylation, and PPAR signalling pathways. Integrated omics analysis showed that the PPAR signalling pathway was the only significantly co-enriched pathway across both omics datasets. This study provides new insights into the molecular mechanisms of compound feed adaptation and provides theoretical support for selecting feed traits in S. chuatsi. Full article

In order to achieve 0.1 m resolution and fully polarimetric observation capabilities for airborne SAR systems, the adoption of stepped-frequency modulation waveform combined with the polarization time-division transmit/receive (T/R) technique proves to be an effective technical approach. Considering the issue of range resolution degradation and paired echoes caused by multichannel amplitude–phase mismatch in fully polarimetric airborne SAR with 0.1 m resolution, an amplitude–phase error estimation algorithm based on echo data is proposed in this paper. Firstly, the subband amplitude spectrum correction curve is obtained by the statistical average of the subband amplitude spectrum. Secondly, the paired-echo broadening function is obtained by selecting high-quality sample points after single-band imaging and the nonlinear phase error within the subbands is estimated via Sinusoidal Frequency Modulation Fourier Transform (SMFT). Thirdly, based on the minimum entropy criterion of the synthesized compressed pulse image, residual linear phase errors between subbands are quickly acquired. Finally, two-dimensional cross-correlation of the image slice is utilized to estimate the positional deviation between polarization channels. This method only requires high-quality data samples from the echo data, then rapidly estimates both intra-band and inter-band amplitude/phase errors by using SMFT and the minimum entropy criterion, respectively, with the characteristics of low computational complexity and fast convergence speed. The effectiveness of this method is verified by the imaging results of the experimental data. Full article