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Synchronizing Semigroups Generated by a Transitive Imprimitive Group and a Transformation
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作者 LI Wangwei LI Xianhua 《数学进展》 北大核心 2026年第2期356-368,共13页
Let T_(n) and S_(n) be the full transformation semigroup and the symmetric group on X_(n)={1,2,...,n},respectively.Let G be a transitiveimprimitive subgroupof S_(n) with nontrivial blocksΔand letαbe a transformation... Let T_(n) and S_(n) be the full transformation semigroup and the symmetric group on X_(n)={1,2,...,n},respectively.Let G be a transitiveimprimitive subgroupof S_(n) with nontrivial blocksΔand letαbe a transformation in T_(n)\S_(n).The kernel ofαis the partition of X_(n) induced by the equivalence relation{(x,y)|xα=yα};the kernel type ofαis the partition of n given by the sizes of the parts of the kernel.A transformation semigroup is called synchronizing if it contains a constant map.Then a group G synchronizes a transformationαif the semigroup(G,α)contains a constant map.In this paper,we study a transitive imprimitive permutation group G together with a non-invertible transformationαthat generate a synchronizing semigroup.We mainly discuss 7 cases where G synchronizes a special transformationαwith each kernel class A_(i)(A_(1)j)satisfying|A_(i)∩Δ|=1(|A_(1)j∩Δ|=1)for all blocksΔofG,that is,the kernel type ofαis(|A_(1)|,1,...,1),(|A_(1)1|,...,|A_(1m)|,|A_(2)|,...,|Ar|),or(|A_(1)|,...,|A_(t)|,1,...,1),or the rank is 2,3,4,or n-2. 展开更多
关键词 transitive imprimitive group completely regular semigroup synchronizing semigroup
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Research Status and Prospects of Platinum Group Metal Coatings with High-Temperature Oxidation Resistance
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作者 Ding Chenxi Liu Zhongyu +3 位作者 Fang Zhen Wang Haoxu Lv Biao Hu Zhenfeng 《稀有金属材料与工程》 北大核心 2026年第2期333-344,共12页
Platinum group metals have high melting points,strong corrosion resistance,stable chemical properties,and low oxygen permeability in high-temperature oxygen-containing environments.As thermal protective coating materi... Platinum group metals have high melting points,strong corrosion resistance,stable chemical properties,and low oxygen permeability in high-temperature oxygen-containing environments.As thermal protective coating materials,they have gained essential applications in the aerospace field and have excellent prospects for application in frontier military fields,such as protecting hot-end components of hypersonic aircraft.This research reviewed the latest research progress of platinum group metal coatings with hightemperature oxidation resistance,including coating preparation techniques,oxidation failure,and alloying modification.The leading preparation techniques of current platinum group metal coatings were discussed,as well as the advantages and disadvantages of various existing preparation techniques.Besides,the intrinsic properties,failure forms,and failure mechanisms of coatings of single platinum group metal in high-temperature oxygen-containing environments were analyzed.On this basis,the necessity,main methods,and main achievements of alloying modification of platinum group metals were summarized.Finally,the future development of platinum group coatings with high-temperature oxidation resistance was discussed and prospected. 展开更多
关键词 platinum group metal coatings preparation technique high temperature oxidation resistance alloying modification
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LOCAL SS-QUASINORMALITY OF SOME SUBGROUPS OF FINITE GROUPS
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作者 WEI Hua-quan WU Hui HE Jia-wen 《数学杂志》 2026年第2期63-74,共12页
This paper investigates the in uence of local SS-quasinormal maximal subgroups of Sylow subgroups on the structure of nite groups.We present several new criteria on p-nilpotency of nite groups by utilizing a small qua... This paper investigates the in uence of local SS-quasinormal maximal subgroups of Sylow subgroups on the structure of nite groups.We present several new criteria on p-nilpotency of nite groups by utilizing a small quantity of local SS-quasinormal maximal subgroups of Sylow p-subgroups.As applications,we obtain some sucient conditions for a nite group to be in a saturated formation containing the class of supersolvable groups. 展开更多
关键词 nite group maximal subgroup p-nilpotent group SS-quasinormal group
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Local Characterizations of Results on the Normal Index of Subgroups in Finite Groups
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作者 Yubo LV Yangming LI Xiaoxia DONG 《Journal of Mathematical Research with Applications》 2026年第1期33-39,共7页
Let G be a finite group and H a subgroup of G.The normal index of H in G is defined as the order of K/H_(G),where K is a normal supplement of H in G such that|K|is minimal and H_(G)≤K■G.Let p be a prime which divide... Let G be a finite group and H a subgroup of G.The normal index of H in G is defined as the order of K/H_(G),where K is a normal supplement of H in G such that|K|is minimal and H_(G)≤K■G.Let p be a prime which divides the order of a group G.In this paper,some characterizations of G being p-solvable or p-supersolvable were obtained by analyzing the normal index of certain subgroups of G.These results can be viewed as local version of recent results in the literature. 展开更多
关键词 p-solvable group p-supersolvable group normal index maximal subgroup 2-maximal subgroup
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Improving Real-Time Animal Detection Using Group Sparsity in YOLOv8:A Solution for Animal-Toy Differentiation
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作者 Zia Ur Rehman Ahmad Syed +3 位作者 Abu Tayab Ghanshyam G.Tejani Doaa Sami Khafaga El-Sayed M.El-kenawy 《Computers, Materials & Continua》 2026年第2期1726-1750,共25页
Object detection,a major challenge in computer vision and pattern recognition,plays a significant part in many applications,crossing artificial intelligence,face recognition,and autonomous driving.It involves focusing... Object detection,a major challenge in computer vision and pattern recognition,plays a significant part in many applications,crossing artificial intelligence,face recognition,and autonomous driving.It involves focusing on identifying the detection,localization,and categorization of targets in images.A particularly important emerging task is distinguishing real animals from toy replicas in real-time,mostly for smart camera systems in both urban and natural environments.However,that difficult task is affected by factors such as showing angle,occlusion,light intensity,variations,and texture differences.To tackle these challenges,this paper recommends Group Sparse YOLOv8(You Only Look Once version 8),an improved real-time object detection algorithm that improves YOLOv8 by integrating group sparsity regularization.This adjustment improves efficiency and accuracy while utilizing the computational costs and power consumption,including a frame selection approach.And a hybrid parallel processing method that merges pipelining with dataflow strategies to improve the performance.Established using a custom dataset of toy and real animal images along with well-known datasets,namely ImageNet,MSCOCO,and CIFAR-10/100.The combination of Group Sparsity with YOLOv8 shows high detection accuracy with lower latency.Here provides a real and resource-efficient solution for intelligent camera systems and improves real-time object detection and classification in environments,differentiating between real and toy animals. 展开更多
关键词 YOLOv8 SPARSITY group sparsity group sparse representation(GSR) CNNS object detection
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Hydrothermal carbon with abundant oxygen-containing functional groups for photocatalytic H_(2)O_(2)generation in water and seawater
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作者 CHANG Yuhong HAN Xue +5 位作者 ZHANG Yanxia LI Guofang HU Tianjun CHEN Wenwen PEI Linjuan JIA Jianfeng 《燃料化学学报(中英文)》 北大核心 2026年第4期160-170,共11页
Photosynthesis of H_(2)O_(2)via sustainable biomass-derived carbon catalysts facilitate the conversion of renewable resources into valuable chemicals.However,the regulatory function of surface functional groups over r... Photosynthesis of H_(2)O_(2)via sustainable biomass-derived carbon catalysts facilitate the conversion of renewable resources into valuable chemicals.However,the regulatory function of surface functional groups over reaction kinetics has not been sufficiently investigated.Herein,hydrothermal carbon spheres(CS)rich in oxygencontaining functional groups demonstrated a remarkably high H_(2)O_(2)production rate(653μmol/(g·h))in both pure water and actual seawater,even in the absence of any sacrificial agent.Meanwhile,the catalyst demonstrates outstanding activity(92%conversion and>99%selectivity)in the visible-light-driven photocatalytic oxidation of benzylamine to imines.Comprehensive analysis reveals that CS was rich in surface oxygen-containing functional groups,a feature strongly associated with its high photocatalytic efficiency.The observed positive Zeta potential of CS in seawater likely diminished the electrostatic repulsion against the positively charged intermediates,thereby facilitating their accumulation at the liquid-solid interface.This work proposes a strategic framework for developing metal-free photocatalysts from biomass,offering a sustainable pathway for photocatalytic applications. 展开更多
关键词 hydrothermal carbon oxygen functional groups photocatalytic H_(2)O_(2)production benzylamine coupling
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TI-subgroups and P-subnormal subgroups and the structure of nite groups
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作者 CHEN Ruifang ZHAO Xianhe 《纯粹数学与应用数学》 2026年第1期33-45,共13页
Let G be a group and H;K be subgroups of G.H is called a TI-subgroup of G if H∩H^(g)=1 or H for every g∈G.K is called P-subnormal in G if there is a chain of subgroups K=K_(0)≤K_(1)≤K_(2)≤…≤K_(n-1)≤K_(n)=G suc... Let G be a group and H;K be subgroups of G.H is called a TI-subgroup of G if H∩H^(g)=1 or H for every g∈G.K is called P-subnormal in G if there is a chain of subgroups K=K_(0)≤K_(1)≤K_(2)≤…≤K_(n-1)≤K_(n)=G such that|K_(i):K_(i-1)|∈P for i∈{1;2;…;n}.Furthermore,K is called K-P-subnormal in G if there is a chain of subgroups K=K_(0)≤K_(1)≤K_(2)≤…≤K_(n-1)≤K_(n)=G such that either K_(i-1)is normal in Ki or|K_(i):K_(i-1)|∈P for i∈{1;2;…;n}.In this paper,some properties of a nite group in which some particular subgroups are TI-subgroups or P-subnormal subgroups or K-P-subnormal subgroups are given. 展开更多
关键词 TI-subgroup P-subnormal subgroup K-P-subnormal subgroup soluble group
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Modulation of titanium dioxide surface hydroxyl groups for photocatalytic selective conversion of biopolyols
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作者 Jian Tang Zhiwei Chen Min Wang 《Journal of Energy Chemistry》 2026年第3期370-376,共7页
Photocatalysis has demonstrated considerable potential as a highly efficient approach to the valorization of biomass under mild conditions,while the selectivity control is a long-standing challenge,notably when the ta... Photocatalysis has demonstrated considerable potential as a highly efficient approach to the valorization of biomass under mild conditions,while the selectivity control is a long-standing challenge,notably when the targets are complex and reactive biopolyols.In this study,we have successfully achieved selectivity control of photocatalytic biopolyols reforming to formic acid(FA)or CO by modulating the surface hydroxyl groups on TiO_(2) semiconductor.Photogenerated holes typically localize at bridging oxygen atoms(O2c)on the TiO_(2) surface,while shifting to terminal hydroxyl groups upon their introduction.The state of holes strongly affects the hole transfer process,which in turn influences the course of the reaction and thus controls the selectivity.By modulating the surface hydroxyl groups,the model substrate glycerol was selectively converted to CO(49%yield)and FA(50%yield).A range of other biopolyols,exemplified by erythritol,have demonstrated the same reaction selectivity.This work provides an effective strategy to manipulate reaction pathways by means of regulating the catalyst surface structure itself. 展开更多
关键词 PHOTOCATALYSIS Biopolyols Interfacial hole transfer Hydroxyl groups
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Prevalence of serotypes,antibiotic resistance and virulence genes of Group B Streptococcus isolated from pregnant women at 35-37 weeks of gestation in Ho Chi Minh City,Vietnam
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作者 Truc-Anh Nguyen-Thi Hong-Phuc Nguyen +3 位作者 Thien-An Do-Hoang Minh-Hoang Tran Tuan-Loc Le Hieu Vu-Quang 《Asian Pacific Journal of Tropical Medicine》 2026年第1期16-24,共9页
Objective:To analyse the prevalence of serotypes,antibiotic resistance,and virulence genes of Group B Streptococcus(GBS)strains isolated from pregnant women at 35-37 weeks of gestation in Ho Chi Minh City,Vietnam,from... Objective:To analyse the prevalence of serotypes,antibiotic resistance,and virulence genes of Group B Streptococcus(GBS)strains isolated from pregnant women at 35-37 weeks of gestation in Ho Chi Minh City,Vietnam,from January 2022 to January 2023.Methods:GBS strains were isolated through selective culture methods and confirmed by PCR.Serotyping,virulence gene detection,and antibiotic susceptibility testing were performed using PCR,gel electrophoresis techniques and Kirby-Bauer test.Results:Totally,61 GBS isolated from 300 participants have been identified including seven GBS serotypes(Ⅰa,Ⅰb,Ⅱ,Ⅲ,Ⅳ,Ⅴ,andⅥ).SerotypesⅦ,Ⅷ,andⅨwere not detected in the study population.Antibiotic resistance patterns varied:13.1%of isolates were fully susceptible,while the majority showed multi-drug resistance,with 34.4%resistant to three antibiotics.SerotypeⅠa demonstrated high susceptibility(35.7%),while serotypeⅢshowed extensive resistance,with 87.5%being resistant to at least three antibiotics.All strains are susceptible to vancomycin andβ-lactams susceptibility also remained high,but resistance to clindamycin,erythromycin,and tetracycline was high(>65%).The virulence genes scpB,cylB,fbsB,and cfb were highly prevalent(90%-100%),indicating their potential for vaccine and diagnostic development.Conclusions:Our findings provide valuable insights into GBS serotypes,resistance,and virulence factors,contributing to community monitoring,preventive measures,diagnostics,and vaccine development.However,the limited sample size necessitates further research. 展开更多
关键词 group B Streptococcus SEROTYPE Antibiotic resistance VIRULENCE PREGNANCY
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Seismic behavior of pile group-supported bridges in liquefiable sloping ground covered with crusts:Insights from experimental observations
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作者 Kemin Jia Chengshun Xu +2 位作者 Junfeng Jia Chao Zhang Xiuli Du 《Journal of Rock Mechanics and Geotechnical Engineering》 2026年第3期1781-1793,共13页
Pile group-supported bridges in liquefied sloping ground with crust are prone to severe damage.However,there remains a limited comprehension of the intricate interactions among pile group,soil,and superstructures,as w... Pile group-supported bridges in liquefied sloping ground with crust are prone to severe damage.However,there remains a limited comprehension of the intricate interactions among pile group,soil,and superstructures,as well as the associated failure mechanisms.To address this issue,this paper presents large-scale shaking table tests conducted on pile group-supported bridges in sloping liquefiable ground with crust to uncover the intricate interaction mechanisms.Firstly,the dynamic characteristics and interaction of the pile-soil-superstructure system were explored.Then,the lateral displacement and acceleration of the superstructure and pile were presented.Next,the curvature and damage characteristics of the pile group-supported bridge were discussed.Finally,through cross-correlation analysis,the study revealed the inertia and kinematic effects,focusing on how the effects influenced the seismic demands.Results indicate that significant differences are observed in pile-soil interactions during strong seismic events depending on the depth and liquefaction stage.As earthquake intensity increases,peak displacement in the superstructure rises linearly while residual displacement grows exponentially.Moreover,the pile group effect becomes more pronounced,especially at the pile head,with the trailing piles showing greater curvature than the leading ones.Due to significant soil lateral spreading and the shadowing effect within the pile group,the leading piles experience prominent kinematic effects from the surface down to the intermediate layer of saturated sand compared to the trailing piles.These findings contribute valuable insights for improving the seismic design approach for bridges with pile groups in sloping liquefied soils. 展开更多
关键词 Liquefiable soil Sloping ground Pile group Pile-soil-structure interaction Seismic behavior
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Reduced matrix integrable hierarchies via group reduction involving off-diagonal block matrices
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作者 Wen-Xiu Ma 《Communications in Theoretical Physics》 2026年第1期1-8,共8页
This paper proposes an innovative form of group reduction or similarity transformation involving off-diagonal block matrices. The proposed method is applied to the Ablowitz-Kaup-Newell-Segur(AKNS) matrix spectral prob... This paper proposes an innovative form of group reduction or similarity transformation involving off-diagonal block matrices. The proposed method is applied to the Ablowitz-Kaup-Newell-Segur(AKNS) matrix spectral problem, leading to the generation of reduced matrix AKNS integrable hierarchies. As a result, a variety of reduced multiple-component integrable nonlinear Schr??dinger and modified Korteweg-de Vries models are derived from the analysis of the reduced AKNS matrix spectral problem. 展开更多
关键词 Lax pair integrable model zero-curvature equation soliton hierarchy group reduction
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Exploratory Practice of Online Group Psychological Counseling with Narrative Painting Therapy
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作者 Pai He Liang Yue +2 位作者 Wenxin Guo Siyao Xu Xinling Wu 《Journal of Clinical and Nursing Research》 2026年第2期122-127,共6页
To explore effective paths for improving college students’ mental health, this study integrates narrative therapy and painting therapy to design a 7-week online group psychological counseling program. A total of 121 ... To explore effective paths for improving college students’ mental health, this study integrates narrative therapy and painting therapy to design a 7-week online group psychological counseling program. A total of 121 volunteer college students participated as subjects, and themed painting counseling was conducted via Tencent Meeting. Five scales, including the General Self-Efficacy Scale, Self-Esteem Scale, and Self-Rating Depression Scale, were used for pre-test and post-test comparisons. The results show that after the intervention, students’ self-efficacy (t = -5.528, p = 0.000) and self-esteem level (t = -2.153, p = 0.033) significantly improved statistically, and depression and anxiety showed a positive improvement trend. The research indicates that online narrative painting therapy can effectively release students’ psychological pressure, promote in-depth self-cognition and interpersonal connection construction, providing an operable innovative paradigm for college mental health education. Its interactivity and effectiveness are compatible with the psychological needs and internet usage habits of contemporary college students. 展开更多
关键词 Mental health education Narrative painting therapy Online group counseling
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Numerical study of a quantum spin in an s-wave superconductor using the natural orbitals renormalization group method
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作者 Wen-Jing Zhang Ru Zheng +1 位作者 Rong-Qiang He Zhong-Yi Lu 《Chinese Physics B》 2026年第2期538-547,共10页
In a superconductor embedded with a quantum magnetic impurity,the Kondo effect is involved,leading to the competition between the Kondo singlet phase and the superconductivity phase.By means of the natural orbitals re... In a superconductor embedded with a quantum magnetic impurity,the Kondo effect is involved,leading to the competition between the Kondo singlet phase and the superconductivity phase.By means of the natural orbitals renormalization group(NORG)method,we revisit the problem of a quantum magnetic impurity coupled with a conventional s-wave superconductor.Here we present a detailed study focusing on the impurity spin polarization and susceptibility,the Kondo screening cloud,as well as the number and structures of the active natural orbitals(ANOs).In the superconducting phase,the impurity spin is partially polarized,indicating that the impurity remains partially screened by the quantum fluctuations.Furthermore,the impurity spin susceptibility becomes divergent,resulting from the presence of residual local moment formed at the impurity site.Correspondingly,a non-integral(incomplete)Kondo cloud is formed,although the ground state is a spin doublet in this phase.In comparison,the Kondo cloud is complete in the Kondo singlet phase as expected.We also quantify the critical point,where the quantum phase transition from a Kondo singlet phase to a superconducting phase occurs,which is consistent with that in previous works.On the other hand,it is illustrated that only one ANO emerges in both quantum phases.The structures of the ANO,projected into both the real space and momentum space,are distinct in the Kondo singlet phase from that in the superconducting phase.More specifically,in the Kondo singlet phase,the ANO keeps fully active with half-occupied,and the superconducting gap has negligible influence on its structure.On the contrary,in the superconducting phase,the ANO tends to be inactive and its structure changes significantly as the superconducting gap increases.Additionally,our investigation demonstrates that the NORG method is reliable and convenient to solve the quantum impurity problems in superconductors as well,which will promote further theoretical studies on the Kondo problems in such systems using numerical methods. 展开更多
关键词 Kondo effect SUPERCONDUCTOR natural orbitals renormalization group active natural orbitals
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Coupling of graphitic microcrystalline and available functional groups in hard carbon unlocking deep and fast potassium-ion storage
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作者 Zhiyuan Liu Hui Peng +6 位作者 Xin Wang Zhenghao Tang Wenbo Hou Bo Tao Yue Li Guofu Ma Ziqiang Lei 《Chinese Chemical Letters》 2026年第2期588-594,共7页
There are limitations to using hard carbon(HC)in K^(+)storage due to its insufficient high-current reversible capacity and plateau potential,which result from the lack of effective active sites and low intercalation c... There are limitations to using hard carbon(HC)in K^(+)storage due to its insufficient high-current reversible capacity and plateau potential,which result from the lack of effective active sites and low intercalation capabilities.The construction of HC cathodes with more available functional groups and ordered carbon nanocrystal structures is essential for improving K^(+)storage efficiency.Herein,a new perspective is proposed for synthesizing hard carbon nanosheets(HCNS)with abundant hydroxyl groups(O-H)/carboxylic groups(O-C=O)and rational carbon nanocrystals by interfacial assembly and carbonization.Systematic in ex-situ observations,dynamic analysis and theory calculations elucidate that the superior electrochemical capability of HCNS is ascribed to the synergistic effect of abundant available functional groups and ordered graphitic microcrystalline.Consequently,the HCNS exhibits outstanding K^(+)storage capabilities in terms of superb energy density(146.2 Wh/kg),high power density(1,7800 Wh/kg),and ultralong lifespan(102.9%capacity retention after 10,000 cycles).It was also found that the HC structure correlates with the discharge/charge plateau,confirming the'adsorption-insertion'charge storage mechanism.Furthermore,the proposed work provides a theoretical basis for making high-performance HC anodes by understanding the effect of their microstructure on K^(+)storage. 展开更多
关键词 Hard carbon Carbon nanosheet Graphitic microcrystalline Availablefunctional groups Potassium ion hybrid capacitors
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International food trade increased the food security gap between high and low economic development groups
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作者 Zihan Xu Tianyi Wu +2 位作者 Tao Hu Yanxu Liu Jian Peng 《Geography and Sustainability》 2026年第1期119-131,共13页
International trade serves as a crucial pathway for enhancing global food security and equality amid severe food crises worldwide.Under globalization,economic development has profoundly influenced food trade,while dis... International trade serves as a crucial pathway for enhancing global food security and equality amid severe food crises worldwide.Under globalization,economic development has profoundly influenced food trade,while disparities in food purchasing power among different economic development groups have led to uneven food security outcomes.However,the varying contributions of international trade to food security across these groups remain to be quantitatively elucidated.This study categorized countries into four economic development groups—high,high-medium,medium-low,and low—and examined changes in their food security scores from 2010 to 2019.The cross-group contributions of international trade to food security across these groups were compared.The results revealed that the food security score of the high economic development group was 9.22 times higher than that of the low economic development group.From 2010 to 2019,the high economic development group exhibited a significant upward trend in food security scores,whereas the low economic development group showed a significant decline.Moreover,international trade contributed significantly to both cross-group and within-group food security in the high economic development group,while its contribution to the low economic development group remained negligible.These findings demonstrated that international trade has further widened the food security gap between the high and low economic development groups,and its limited contribution to the low economic development group has failed to reverse the declining trend in their food security scores.This study quantified the divergent impacts of international trade on food security across economic development groups,providing valuable insights for optimizing global food trade policies—particularly in addressing the food security challenges faced by low econominc development group. 展开更多
关键词 Food supply and demand Food security International trade Economic development group Cross-regional
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船舶管理行业还将持续分化——访V.Group首席执行官René Kofod-Olsen
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作者 薛龙玉 《中国船检》 2026年第3期40-44,共5页
2026年1月,全球船舶管理与海事服务集团V.Group宣布完成对航运脱碳解决方案提供商Njord的收购。这家由马士基油轮于2019年孵化的企业,将作为V.Group旗下的核心脱碳品牌,整合至其V.Services平台。
关键词 V.group V.Services Njord 首席执行官 航运脱碳
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Effect of fluorination positions at diphenylamino flanking groups on the photovoltaic performance for nonfused ring electron acceptors
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作者 Yang Gao Huarui Zhang +7 位作者 Yan Xie Xinjun Xu Yahui Liu Hao Lu Wenkai Zhang Yuqiang Liu Cuihong Li Zhishan Bo 《Chinese Chemical Letters》 2026年第1期368-373,共6页
The fluorination strategy has been proven effective in significantly enhancing the photovoltaic performance of organic solar cells(OSCs) based on non-fused ring electron acceptors(NFREAs).However,research on the impac... The fluorination strategy has been proven effective in significantly enhancing the photovoltaic performance of organic solar cells(OSCs) based on non-fused ring electron acceptors(NFREAs).However,research on the impact of fluorination positions at side chains on NFREAs device performance remains scant.In this study,we introduce two isomeric NFREAs,designated as GA-2F-E and GA-2F,distinguished by their fluorination positions at the side chains.Both NFREAs share a thiophene[3,2-b]thiophene core,but their side chains differ:GA-2F-E features two(4-butylphenyl)-N-(4-fluorophenyl) amino groups,whereas GA-2F's side chains consist of bis(4-fluorophenyl)amino and bis(4-butylphenyl)amino groups attached to opposite sides of the core.To delve into the influence of fluorination positions on the optoelectronic properties,aggregation behavior,and overall efficiency of the acceptor molecules,a comprehensive investigation was conducted.The findings reveal that,despite similar photophysical properties and comparable absorption bandwidths,GA-2F-E,with fluorine atoms positioned on both sides of the molecular framework,demonstrates more compact π-π stacking,reduced bimolecular recombination,superior exciton transport,and a more balanced,higher mobility.As a result of these advantages,OSCs optimized with D18:GA-2F-E achieve a remarkable power conversion efficiency(PCE) of 16.45 %,surpassing the 15.83 %PCE of devices utilizing D18:GA-2F.This research underscores the potential of NFREAs in future applications and highlights the significance of fluorination positions in enhancing OSC performance,paving the way for the development of more efficient NFREAs. 展开更多
关键词 Organic solar cells Non-fused ring electron acceptors Fluorination position Diphenylamino groups Power conversion efficiencies
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Fundamental groups of manifolds of positive sectional curvature
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作者 RONG Xiaochun 《首都师范大学学报(自然科学版)》 2026年第1期1-13,27,共14页
Let M be a compact n-manifold of positive sectional curvature.We will review classical results on the fundamental group of M,a motivation on the c(n)-cyclic conjecture that the fundamental group of M contains a cyclic... Let M be a compact n-manifold of positive sectional curvature.We will review classical results on the fundamental group of M,a motivation on the c(n)-cyclic conjecture that the fundamental group of M contains a cyclic subgroup of index bounded above by c(n),a constant depending only on n,and we will survey partial results(up to date)on the c(n)-cyclic conjecture. 展开更多
关键词 positive sectional curvature conjecture on almost cyclic fundamental groups equivariant Gromov-Hausdorff convergence Alexandrov geometry
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Study and improvement of a multivariate covariance control chart based on the Sparse Group Lasso penalty
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作者 Jun Hua Hongwei Li +1 位作者 Chunjie Wu Jialin Wu 《Statistical Theory and Related Fields》 2026年第1期82-116,共35页
Traditional multivariate parametric control charts often perform inadequately in detecting shifts in the covariance matrix when the data deviate from normality.In this paper,we propose a multivariate nonparametric exp... Traditional multivariate parametric control charts often perform inadequately in detecting shifts in the covariance matrix when the data deviate from normality.In this paper,we propose a multivariate nonparametric exponentially weighted moving average(SGLGEWMA)control chart,incorporating a Sparse Group Lasso penalty,which is capable of detecting shifts in the covariance matrix across a wide range of data types,including discrete,continuous,and mixed distributions.The proposed approach projects multivariate data into a Euclidean space and then computes an approximate Alt’s likelihood ratio,regularized via the Sparse Group Lasso.The resulting EWMA statistic monitors process shifts.Monte Carlo simulations demonstrate that SGLGEWMA outperforms both the Lasso-based LGShewhart and the Ridge-based RGEWMA control charts under various distributions,with enhanced efficacy in high-dimensional scenarios.Sensitivity analyses are performed on the tuning parameters(λ_(1),λ_(2))and smoothing parameterρ,to evaluate their impact on monitoring performance.Additionally,a simulation study and an illustrative example involving covariance monitoring in wafer semiconductor manufacturing are presented to demonstrate the practical application of the proposed chart.Empirical results confirm that the proposed control chart promptly identifies abnormal fluctuations and issues timely alerts,highlighting both its theoretical significance and practical utility. 展开更多
关键词 Covariance monitoring nonparametric method sparse group Lasso penalty principal coordinate analysis statistical process monitoring(SPM)
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