期刊：
Journal of Heterocyclic Chemistry,2024年61(4) ISSN：0022-152X
通讯作者：
Liu, Aiping;Lan, SL;Xie, JJ
作者机构：
[Xie, Jianjun; Li, Guojun] Cent South Univ Forestry & Technol, Sch Mat Sci & Engn, Changsha, Peoples R China.;[Lan, Shilin; Ouyang, Wensen; Liu, Aiping; Long, Chuyun; Li, Jun; Li, Guojun; Li, Jianming; Xiao, Ting; Hu, Li] Hunan Res Inst Chem Ind, Natl Engn Res Ctr Agrochem, Changsha, Peoples R China.;[Liu, Aiping] Hunan Prov Key Lab Agrochem, Changsha, Peoples R China.;[Xiao, Ting] Changsha Univ Sci & Technol, Sch Chem & Chem Engn, Changsha, Peoples R China.;[Lan, Shilin; Liu, Aiping; Liu, AP; Lan, SL] Hunan Res Inst Chem Ind, Natl Engn Res Ctr Agrochem, Changsha 410007, Peoples R China.
通讯机构：
[Liu, AP; Lan, SL ] H;[Xie, JJ ] C;Hunan Res Inst Chem Ind, Natl Engn Res Ctr Agrochem, Changsha 410007, Peoples R China.;Cent South Univ Forestry & Technol, Sch Mat Sci & Engn, Changsha 410004, Peoples R China.
摘要：
By connecting the key intermediate trifluoroethyl sulfide with pyrimidinamine, we obtained T4 with LC50 was 0.19 mg/L against T. urticae and T15 with EC50 was 1.32 mg/L against P. sorghi after active testing and structural optimization. Abstract In order to overcome the problem of pesticide resistance, it is necessary to discover novel pesticides with new mechanisms of action. Herein, a series of novel pyrimidin‐4‐amine derivatives containing trifluoroethyl sulfide moiety were designed and synthesized. Bioassays indicated that the title compounds synthesized possessed excellent acaricidal activity against Tetranychus urticae and fungicidal activity against Erysiphe graminis and Puccinia sorghi. Especially, the acaricidal activity of 5‐chloro‐6‐(difluoromethyl)‐N‐(2‐(2‐fluoro‐4‐methyl‐5‐((2,2,2‐trifluoroethyl)thio)phenoxy)ethyl)pyrimidin‐4‐amine (compound T4, LC50 = 0.19 mg/L) against T. urticae was close to commercial acaricide cyenopyrafen, and the fungicidal activity of 5‐chloro‐6‐(difluoromethyl)‐2‐methyl‐N‐(2‐(3‐((2,2,2‐trifluoroethyl)thio)phenoxy)ethyl)pyrimidin‐4‐amine (compound T15, EC50 = 1.32 mg/L) against P. sorghi. was superior to commercial fungicide tebuconazole. The synthesis and characterization of these compounds were given and the structure–activity relationships were discussed.
摘要：
The modulation mechanism of iron (Fe) and manganese (Mn) in transition-metal elements on the interface bonding and mechanical properties of bronze (Cu3Sn)-based/diamond composites is investigated through first-principles calculations. Transition-elements-doping scenarios are investigated employing six-layer slab models. It is revealed that the doping of Fe or Mn can make the Cu3Sn/diamond interface more stable, which effectively improves the wettability of the Cu3Sn/diamond interface based on the calculation results and analysis of interface energy, differential charge density model, and density of states. However, co-doping with both Fe and Mn weakens the wettability of the Cu3Sn/diamond interface. Finally, wettability tests and microstructure characterizations demonstrate that the doping of Fe and Mn represents an effective approach to controlling the interface bonding performance of bronze/diamond composites. Fe- and Mn-doping effects on the interface binding and mechanical properties of Cu3Sn/diamond composites are studied using first-principles calculations. Analysis of interface energy, charge density models, and density of states reveals that individual Fe or Mn doping improves Cu3Sn//diamond interface wettability. Conversely, co-doping weakens Cu3Sn/diamond interface wettability. Wettability tests and microscopic characterization validate these findings.image (c) 2023 WILEY-VCH GmbH
摘要：
Wildfires and post-fire management exert profound effects on soil properties and microbial communities in forest ecosystems. Understanding microbial community recovery from fire and what the best post-fire management should be is very important but needs to be sufficiently studied. In light of these gaps in our understanding, this study aimed to assess the short-term effects of wildfire and post-fire management on both bacteria and fungi community composition, diversity, structure, and co-occurrence networks, and to identify the principal determinants of soil processes influencing the restoration of these communities. Specifically, we investigated soil bacterial and fungal community composition, diversity, structure, and co-occurrence networks in lower subtropical forests during a short-term (<3 years) post-fire recovery period at four main sites in Guangdong Province, southern China. Our results revealed significant effects of wildfires on fungal community composition, diversity, and co-occurrence patterns. Network analysis indicated reduced bacterial network complexity and connectivity post-fire, while the same features were enhanced in fungal networks. However, post-fire management effects on microbial communities were negligible. Bacterial diversity correlated positively with soil microbial biomass nitrogen, soil organic carbon, and soil total nitrogen. Conversely, based on the best random forest model, fungal community dynamics were negatively linked to nitrate-nitrogen and soil water content. Spearman's correlation analysis suggested positive associations between bacterial networks and soil factors, whereas fungal networks exhibited predominantly negative associations. This study elucidates the pivotal role of post-fire management in shaping ecological outcomes. Additionally, it accentuates the discernible distinctions between bacterial and fungal responses to fire throughout a short-term recovery period. These findings contribute novel insights that bear significance in evaluating the efficacy of environmental management strategies.
作者机构：
[Xiangyun Ding; Zeshuai Deng; Xin Xia; Mu Zhang; Bing Zhang] Institute of Wildlife Conservation, Central South University of Forestry and Technology, Changsha 410004, China;Author to whom correspondence should be addressed.;[Guoxing Deng; Xiangying Chen] Administration Bureau of Hunan Mangshan National Nature Reserve, Chenzhou 423000, China;[Daode Yang] Institute of Wildlife Conservation, Central South University of Forestry and Technology, Changsha 410004, China<&wdkj&>Author to whom correspondence should be addressed.
通讯机构：
[Daode Yang] I;Institute of Wildlife Conservation, Central South University of Forestry and Technology, Changsha 410004, China<&wdkj&>Author to whom correspondence should be addressed.
摘要：
This study explores the critical issue of understanding the potential impacts of climate change on the habitat suitability of the highly endangered forest-dwelling Mangshan pit viper (Protobothrops mangshanensis) in China. Through the application of the MaxEnt model, high-resolution bioclimatic datasets, and species occurrence data, the research aims to elucidate the spatial and temporal dynamics of P. mangshanensis distribution from the present to the years 2050 and 2070. Through the integration of three climate models from the Coupled Model Intercomparison Project Phase 6 (CMIP6) and exploring different shared socioeconomic pathway (SSP) scenarios (SSP126, SSP370, and SSP585), the study seeks to provide comprehensive insights into the potential variations in habitat suitability under diverse future climate conditions. The methodology employed involves the construction of the MaxEnt model utilizing the BioClim dataset and 83 species occurrence points. The SSP scenarios mentioned above represent future climate change scenarios, and the accuracy of the model is evaluated using the area under the receiver-operating characteristic (ROC) curve (AUC). Key findings reveal that the MaxEnt model exhibits high accuracy (AUC = 0.998), pinpointing the current suitable habitat for P. mangshanensis to be confined to the Mangshan area within the Nanling Mountains, covering an approximate area of 1023.12 km2. However, projections based on future climate scenarios suggest notable shifts in habitat suitability dynamics. While potential suitable habitats may emerge in the northwest of the current range, the existing suitable habitats are anticipated to undergo significant reduction or even complete disappearance. Notably, precipitation during the driest month emerges as a critical determinant influencing the distribution of the species. In conclusion, the study underscores the exacerbating impact of climate change on habitat deterioration and survival risks for P. mangshanensis, emphasizing the urgent need for conservation measures to safeguard the remaining suitable habitats for this endangered species. The implications of these findings are far-reaching, with the anticipated contraction of the snake’s range potentially leading to its disappearance and increased habitat fragmentation. By shedding light on the potential distributional changes of P. mangshanensis in Mangshan, the research provides valuable insights for informing targeted conservation strategies and policy interventions aimed at mitigating the adverse effects of climate change on endangered species.
摘要：
This paper proposes a novel type of cold-formed steel (CFS) built-up closed L-shaped section column (CSBC-L). The CSBC-L is a part of the novel special built-up column prefabricated modularized mid-rise CFS structural system (SPMM-CFS), and it can be used to compose the corner-column modulus. The CSBC-L can install sheathing walls in two crossed directions without any other connecting components, and it exhibits large torsional stiffness and inertia moment. This paper conducted experimental investigations on the compressive behavior of CSBC-L with different configurations. Totally 18 test specimens with different plate thicknesses, web heights and screw spacings were designed and tested. The results show that the ultimate strength of CSBC-L can be effectively improved with increasing the web height and plate thickness. Finite element (FE) models were developed for the test specimens, and the failure modes as well as the nonlinear load-displacement curves were simulated and validated. Finally, the effective width method (EWM) and direct strength method (DSM) are used to predict the ultimate strength of the CSBC-L specimens in AISI S100-16 and EN 1993-1-3. It is found that the DSM is more accurate to predict the axial compressive ultimate strength, and most of the errors are less than 10%.
摘要：
BACKGROUND: Camellia oleifera, an essential woody oil tree in China, propagates through grafting. However, in production, it has been found that the interaction between rootstocks and scions may affect fruit characteristics. Therefore, it is necessary to predict fruit characteristics after grafting to identify suitable rootstock types. METHODS: This study used Deep Neural Network (DNN) methods to analyze the impact of 106 6-year-old grafting combinations on the characteristics of C.oleifera, including fruit and seed characteristics, and fatty acids. The prediction of characteristics changes after grafting was explored to provide technical support for the cultivation and screening of specialized rootstocks. After determining the unsaturated fat acids, palmitoleic acid C16:1, cis-11 eicosenoic acid C20:1, oleic acid C18:1, linoleic acid C18:2, linolenic acid C18:3, kernel oil content, fruit height, fruit diameter, fresh fruit weight, pericarp thickness, fresh seed weight, and the number of fresh seeds, the DNN method was used to calculate and analyze the model. The model was screened using the comprehensive evaluation index of Mean Absolute Error (MAPE), determinate correlation R(2) and and time consumption. RESULTS: When using 36 neurons in 3 hidden layers, the deep neural network model had a MAPE of less than or equal to 16.39% on the verification set and less than or equal to 13.40% on the test set. Compared with traditional machine learning methods such as support vector machines and random forests, the DNN method demonstrated more accurate predictions for fruit phenotypic characteristics, with MAPE improvement rates of 7.27 and 3.28 for the 12 characteristics on the test set and maximum R(2) improvement values of 0.19 and 0.33. In conclusion, the DNN method developed in this study can effectively predict the oil content and fruit phenotypic characteristics of C. oleifera, providing a valuable tool for predicting the impact of grafting combinations on the fruit of C. oleifera.
摘要：
The deterioration of food freshness and occurrence of spoilage is attributed to adverse external conditions during storage, leading to unnecessary waste and posing food safety concerns. Therefore, it is imperative to develop packaging that monitors and maintains food freshness. Intelligent and active packaging precisely meets these desired requirements. Intelligent packaging has the potential to offer real-time feedback on environmental changes within the packaging, providing valuable information about food quality and safety. On the other hand, active packaging represents a novel approach that incorporates active ingredients, such as antimicrobials into packages to enhance food quality. This review highlights recent advancements in dual -functional packaging utilizing various plant essential oils and pH -sensitive natural pigments. It explores different methods, with a focus on electrospinning, and also discusses existing challenges and future trends. This information aims to assist in the development of packaging systems, offering a new direction for the development of antibacterial and pHsensitive packaging.
作者机构：
[Ziyi Wang; Xiaoyuan Luo] School of Materials Science and Engineering, Central South University of Forestry, Changsha 410004, China;Author to whom correspondence should be addressed.;[Xiaogang Duan] Central South Intelligence Collaborative Research Center, Changsha 410004, China;[Yihua Li] School of Logistics & Traffic, Central South University of Forestry, Changsha 410004, China;[Wenjing Huang] School of Materials Science and Engineering, Central South University of Forestry, Changsha 410004, China<&wdkj&>Author to whom correspondence should be addressed.
通讯机构：
[Wenjing Huang] S;School of Materials Science and Engineering, Central South University of Forestry, Changsha 410004, China<&wdkj&>Author to whom correspondence should be addressed.
摘要：
Surface electromyography (sEMG) signals are the sum of action potentials emitted by many motor units; they contain the information of muscle contraction patterns and intensity, so they can be used as a simple and reliable source for grasping mode recognition. This paper introduces the InRes-ACNet (inception–attention–ACmix-ResNet50) model, a novel deep-learning approach based on ResNet50, incorporating multi-scale modules and self-attention mechanisms. The proposed model aims to improve gesture recognition performance by enhancing its ability to extract channel feature information within sparse sEMG signals. The InRes-ACNet model is evaluated on the NinaPro DB1 and NinaPro DB5 datasets; the recognition accuracy for these datasets can reach 87.94% and 87.04%, respectively, and recognition accuracy can reach 88.37% in the grasping mode prediction of an electromyography manipulator. The results show that the fusion of multi-scale modules and self-attention mechanisms endows a strong ability for the task of gesture recognition based on sparse sEMG signals.
作者机构：
[Li, Zhi; Zhu, Mingshan; Zhou, Daixi] Jinan Univ, Sch Environm, Guangdong Key Lab Environm Pollut & Hlth, Guangzhou 511443, Peoples R China.;[Hu, Xinjiang] Cent South Univ Forestry & Technol, Coll Environm Sci & Engn, Changsha 410004, Peoples R China.;[Chen, Li] Chinese Peoples Liberat Army Gen Hosp, Med Ctr 1, Dept Gen Practice, Beijing 100853, Peoples R China.
通讯机构：
[Chen, L ] C;[Zhu, MS ] J;Jinan Univ, Sch Environm, Guangdong Key Lab Environm Pollut & Hlth, Guangzhou 511443, Peoples R China.;Chinese Peoples Liberat Army Gen Hosp, Med Ctr 1, Dept Gen Practice, Beijing 100853, Peoples R China.
关键词：
advanced oxidation process;persulfate;reactive oxygen species;single atom catalysts;substance
摘要：
In this review, SACs with different metal species and substrates are summarized to investigate the metal−support interaction effects on the persulfate oxidation reaction for water treatments. Abstract With maximum utilization of active metal sites, more and more researchers have reported using single atom catalysts (SACs) to activate persulfate (PS) for organic pollutants removal. In SACs, single metal atoms (Fe, Co, Cu, Mn, etc.) and different substrates (porous carbon, biochar, graphene oxide, carbon nitride, MOF, MoS2, and others) are the basic structural. Metal single atoms, substances, and connected chemical bonds all have a great influence on the electronic structures that directly affect the activation process of PS and degradation efficiency to organic pollutants. However, there are few relevant reviews about the interaction between metal single atoms and substances during PS activation process. In this review, the SACs with different metal species and substrates are summarized to investigate the metal−support interaction and evaluate their effects on PS oxidation reaction process. Furthermore, how metal atoms and substrates affect the reactive species and degradation pathways are also discussed. Finally, the challenges and prospects of SACs in PS‐AOPs are proposed.
作者机构：
[Niu, Guoxiang] Chinese Acad Sci, Lushan Bot Garden, Jiujiang 332900, Peoples R China.;[Liu, Tao] Cent South Univ Forestry & Technol, Natl Engn Lab Appl Technol Forestry & Ecol South C, Changsha 410004, Peoples R China.;[Zhao, Zhen; Lu, Xiankai; Niu, Guoxiang; He, Xiaoxiang; Guan, Huiling; Liu, Tao; Zhang, Xuebing] Chinese Acad Sci, Key Lab Vegetat Restorat & Management Degraded Eco, South China Bot Garden, Guangzhou 510650, Peoples R China.;[Niu, Guoxiang] Lund Univ, Dept Biol, Sect Microbial Ecol, S-22362 Lund, Sweden.;[Liu, Tao] Lutou Natl Stn Sci Observat & Res Forest Ecosyst H, Yueyang 414000, Peoples R China.
通讯机构：
[Liu, T ] C;Cent South Univ Forestry & Technol, Natl Engn Lab Appl Technol Forestry & Ecol South C, Changsha 410004, Peoples R China.
关键词：
Tropical and subtropical forest;Soil organic matter fractions;Earthworm;Millipedes;Litter decomposition
摘要：
Background: Forest soils in tropical and subtropical areas store a significant amount of carbon. Recent frameworks to assess soil organic matter (SOM) dynamics under evolving global conditions suggest that dividing bulk SOM into particulate and mineral -associated organic matter (POM vs. MAOM) is a promising method for identifying how SOM contributes to reducing global warming. Soil macrofauna, earthworms, and millipedes have been found to play an important role in facilitating SOM processes. However, how these two co-existing macrofaunae impact the litter decomposition process and directly impact the formation of POM and MAOM remains unclear. Methods: Here, we set up a microcosm experiment, which consisted of 20 microcosms with four treatments: earthworm and litter addition (E), millipedes and litter addition (M), earthworm, millipedes, and litter addition (E+M), and control (only litter addition) in five replicates. The soil and litter were sterilized prior to beginning the incubation experiment to remove any existing microbes. After incubating the samples for 42 days, the litter properties (mass, C, and N contents), soil physicochemical properties, as well as the C and N contents, and POM and MAOM 13C abundance in the 0-5 and 5-10 cm soil layers were measured. Finally, the relative influences of soil physicochemical and microbial properties on the distribution of C and N in the soil fractions were analyzed. Results: The litter mass, C, and N associated with all four treatments significantly decreased after incubation, especially under treatment E+M (litter mass: -58.8%, litter C: -57.0%, litter N: -75.1%, respectively), while earthworm biomass significantly decreased under treatment E. Earthworm or millipede addition alone showed no significant effects on the organic carbon (OC) and total nitrogen (TN) content in the POM fraction, but joint addition of both significantly increased OC and TN regardless of soil depth. Importantly, all three macrofauna treatments increased the OC and TN content and decreased the 13C abundance in the MAOM fraction. More than 65% of the total variations in the distribution of OC and TN throughout the two fractions can be explained by a combination of soil physicochemical and microbial properties. Changes in the OC distribution in the 0-5 cm soil layer are likely due to a decrease in soil pH and an increase in arbuscular mycorrhizal fungi (AMF), while those in the 5-10 cm layer are probably caused by increases in soil exchangeable Ca and Mg, in addition to fungi and gram -negative (GN) bacteria. The observed TN distribution changes in the 0-5 cm soil likely resulted from a decrease in soil pH and increases in AMF, GN, and gram -negative (GP) bacteria, while TN distribution changes in the 5-10 cm soil could be explained by increases in exchangeable Mg and GN bacteria. Conclusions: The results indicate that the coexistence of earthworms and millipedes can accelerate the litter decomposition process and store more C in the MAOM fractions. This novel finding helps to unlock the processes by which complex SOM systems serve as C sinks in tropical forests and addresses the importance of soil macrofauna in maintaining C -neutral atmospheric conditions under global climate change.
期刊：
International Journal of Biological Macromolecules,2024年:131498 ISSN：0141-8130
通讯作者：
Luo, Feijun;Lin, Qinlu
作者机构：
[Yang, Feiyan; Wu, Yuchi; Qin, Dandan; Hu, Zuomin] College of Food Science and Engineering, Central South University of Forestry and Technology, Changsha 410004, Hunan, China;[Luo, Yidan] College of Life Science and Technology, Central South University of Forestry and Technology, Changsha 410004, Hunan, China;[Luo, Feijun] College of Food Science and Engineering, Central South University of Forestry and Technology, Changsha 410004, Hunan, China. Electronic address: luofeijun888@csuft.edu.cn;[Lin, Qinlu] College of Food Science and Engineering, Central South University of Forestry and Technology, Changsha 410004, Hunan, China. Electronic address: linqinlu@hotmail.com
通讯机构：
[Luo, Feijun; Lin, Qinlu] C;College of Food Science and Engineering, Central South University of Forestry and Technology, Changsha 410004, Hunan, China. Electronic address:
摘要：
Momordica charantia L. is a kind of vegetable with medicinal value. As the main component of the vegetable, Momordica charantia polysaccharides (MCPs) mainly consist of galactose, galacturonic acid, xylose, rhamnose, mannose and the molecular weight range is 4.33 × 10(3)-1.16 × 10(6) Da. MCPs have been found to have various biological activities in recent years, such as anti-oxidation, anti-diabetes, anti-brain injury, anti-obesity, immunomodulatory and anti-inflammation. In this review, we systematically summarized the extraction methods, structural characteristics and physicochemical properties of MCPs. Especially MCPs modulate gut microbiota and cause the alterations of metabolic products, which can regulate different signaling pathways and target gene expressions to exert various functions. Meanwhile, the potential structure-activity relationships of MCPs were analyzed to provide a scientific basis for better development or modification of MCPs. Future researches on MCPs should focus on industrial extraction and molecular mechanisms. In East Asia, Momordica charantia L. is used as both food and medicine. It is not clear whether MCP has its unique biological effects. Further study on the difference between MCPs and other food-derived polysaccharides will be helpful to the development and potential application of Momordica charantia L.
作者机构：
[Ning Zhang] College of Science, Central South University of Forestry and Technology, Changsha 410004, P. R. China;[Dandan Gao; Ziyu Zhuang] Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, P. R. China;Key Lab of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Chinese Academy of Sciences, Xining 810008, P. R. China;College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, P.R. China;[Dongdong Li] Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, P. R. China<&wdkj&>Key Lab of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Chinese Academy of Sciences, Xining 810008, P. R. China
通讯机构：
[Dongdong Li] Q;Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, P. R. China<&wdkj&>Key Lab of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Chinese Academy of Sciences, Xining 810008, P. R. China
摘要：
Lithium aluminum layered double hydroxide chlorides (LADH-Cl) have been widely used for lithium extraction from brine. Elevation of the performances of LADH-Cl sorbents urgently requires knowledge of the composition-structure-property relationship of LADH-Cl in lithium extraction applications, but these are still unclear. Herein, combining the phase equilibrium experiments, advanced solid characterization methods, and theoretical calculations, we constructed a cyclic work diagram of LADH-Cl for lithium capture from aqueous solution, where the reversible (de)hydration and (de)intercalation induced phase evolution of LADH-Cl dominates the apparent lithium "adsorption-desorption" behavior. It is found that the real active ingredient in LADH-Cl type lithium sorbents is a dihydrated LADH-Cl with an Al:Li molar ratio varying from 2 to 3. This reversible process indicates an ultimate reversible lithium (de)intercalation capacity of ∼10 mg of Li per g of LADH-Cl. Excessive lithium deintercalation results in the phase structure collapse of dihydrated LADH-Cl to form gibbsite. When interacting with a concentrated LiCl aqueous solution, gibbsite is easily converted into lithium saturated intercalated LADH-Cl phases. By further hydration with a diluted LiCl aqueous solution, this phase again converts to the active dihydrated LADH-Cl. In the whole cyclic progress, lithium ions thermodynamically favor staying in the Al-OH octahedral cavities, but the (de)intercalation of lithium has kinetic factors deriving from the variation of the Al-OH hydroxyl orientation. The present results provide fundamental knowledge for the rational design and application of LADH-Cl type lithium sorbents.
作者机构：
[Haifei Chen; Zhifeng Yang; Jianan Liu; Zhong Xi] Engineering Research Center for Forestry Equipment of Hunan Province, Central South University of Forestry and Technology, Changsha 410004, China;[Jianwu Yu; Kaifeng Huang] College of Mechanical and Vehicle Engineering, Hunan University, Changsha 410082, China;Author to whom correspondence should be addressed.;[Hong Luo] Engineering Research Center for Forestry Equipment of Hunan Province, Central South University of Forestry and Technology, Changsha 410004, China<&wdkj&>College of Mechanical and Vehicle Engineering, Hunan University, Changsha 410082, China<&wdkj&>Author to whom correspondence should be addressed.
通讯机构：
[Hong Luo] E;Engineering Research Center for Forestry Equipment of Hunan Province, Central South University of Forestry and Technology, Changsha 410004, China<&wdkj&>College of Mechanical and Vehicle Engineering, Hunan University, Changsha 410082, China<&wdkj&>Author to whom correspondence should be addressed.
摘要：
The optimal tuning of high-order motion parameters has emerged as a promising strategy for actively controlling the kinematics/dynamics of high-speed cam mechanisms. However, accomplishing this task remains challenging with current low-order interpolation or tuning methods. This study proposes an integrated high-order interpolation and tuning methodology for the optimal construction of high-speed motion curves. Initially, an explicit C4-spline interpolant (C4SI) is developed. This interpolant utilizes four-order continuous (C4) splines to synthesize a high-fidelity motion curve that satisfies the predefined motion constraints up to the fourth order, including dimensionless displacement, velocity, acceleration, jerk, and quirk. Concerning the reduction of motion peaks, a unique C4SI-based global kinematics optimization strategy is designed, using the definite integral of the motion curve (free of the time variable) as the objective function. This facile time-free optimization strategy could yield a simultaneous reduction in multiple motion peaks (up to five), which is currently inaccessible with conventional motion tuning strategies. Concerning the improvement of dynamic characteristics, the C4SI-based time-free global dynamics optimization of variable motion parameters is further performed. The results indicate that the optimized fourth-order motion curve offers minimal high-speed transmission error and residual vibration over the whole rise-dwell-return-dwell cycle, which outperforms the standard motion curves and other low-order counterparts.
摘要：
Both financial development and technological innovation are critical issues for policy-makers and academics in high-quality economic development. From the perspective of the geographical structure of the financial supply, this paper measures the number of financial institutions within a certain radius around an enterprise using the information on its geographical location and that of surrounding financial institutions to explore the impact of financial density on the enterprise's innovation quality, as well as the transmission mechanism. Rising financial density improves enterprise innovation quality, and this enhancement effect is mainly manifested in patent generality rather than patent originality. As the geographic radius expands, the effect of financial density on enterprise innovation quality increases and then decreases. Financial accessibility and competitive banking channels are the primary transmission mechanisms of financial density on enterprise innovation quality. In addition, the promotional effect of financial density on enterprise innovation quality is heterogeneous according to regional, industry, and enterprise characteristics. Finally, further analysis indicates that financial density will promote both innovation quality and quantity by motivating firms to engage in patent R&D behaviors that are highly technologically advanced. In addition, financial density enhances enterprises' innovation efficiency by increasing bank competition. Similarly, financial density is also conducive to increasing enterprises' commercial credit and financial liabilities. Therefore, the government should accelerate the development of an inclusive financial system, improve the coverage and penetration rates of the spatial layout of financial institutions, and encourage high-quality economic development by encouraging technologically advanced and innovative firms.
