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Spacelike Framed Curves with Lightlike Components and Singularities of Their Evolutes and Focal Surfaces in Minkowski 3-space

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Acta Mathematica Sinica,English Series 2024年第6期40卷 1521-1532页

作者： Peng cheng LI dong He PEI Xin ZHAO School of Mathematics and Statistics Northeast Normal UniversityChangchun 130024P.R.China Department of Mathematics Harbin Institute of TechnologyWeihai 264209P.R.China School of Mathematics and Statistics Qingdao UniversityQingdao 266071P.R.China

In this paper,we define the evolute and focal surface of a spacelike framed curve with lightlike components in Minkowski *** is a generalization of the previous results of regular spacelike curves,since singularities are allowed in the original spacelike curves studied by spacelike framed curves with lightlike ***,we show a new geometric invariant to characterise singularities of the focal ***,the classification theorem and recognition theorem for the singularities of the focal surface in generic are also given.

关键词： Evolutes focal surfaces spacelike framed curves singularities

Experimental investigation on weak shock wave mitigation characteristics of flexible polyurethane foam and polyurea

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Defence Technology（防务技术） 2024年第1期31卷 179-191页

作者： Shiyu Jia cheng Wang Wenlong Xu dong Ma Fangfang Qi State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081China Institute for Advanced Technology Shandong UniversityJinan250061China

In recent years,explosion shock wave has been considered as a signature injury of the current military *** strong shock wave is lethal to the human body,weak shock wave can cause many more lasting *** investigate the protection ability and characteristics of flexible materials and structures under weak shock wave loading,the blast wave produced by TNT explosive is loaded on the polyurethane foam with the density of 200.0 kg/m3(F-200)and 400.0 kg/m3(F-400),polyurea with the density of 1100.0 kg/m^(3)(P-1100)and structures composed of the two materials,which are intended for individual *** results indicate that the shock wave is attenuated to weak pressure disturbance after interacting with the flexible materials which are not *** shock wave protective capability of single-layer materials is dependent on their thickness,density and microscopic *** overpressure,maximum pressure rise rate and impulse of transmitted wave decrease exponentially with increase in sample *** the same thickness,F-400 provides better protective capability than F-200 while P-1100 shows the best protective capability among the three *** this study,as the materials are not destroyed,F-200 with a thickness more than10.0 mm,F-400 with a thickness more than 4.0 mm,and P-1100 with a thickness more than 1.0 mm can attenuate the overpressure amplitude more than 90.0%.Further,multi-layer flexible composites are *** layer layouts of designed structures and layer thickness of the single-layer materials can affect the protective *** the research range,the structure in which polyurea is placed on the impact side shows the optimal shock wave protective performance,and the thicknesses of polyurea and polyurethane foam are 1.0 mm and 4.0 mm *** overpressure attenuation rate reached maximum value of 93.3%and impulse attenuation capacity of this structure are better than those of s

关键词： Free-field explosion Weak shock wave mitigation Polyurea Polyurethane foam Multi-layered composites

Strengthened and toughened SiHfBCN-based hightemperature resistant adhesive with SiC NWs

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Chinese Journal of Aeronautics 2024年第7期37卷 539-549页

作者： Xingang LUAN Xiyue ZHU Xichao dong Min LI Laifei cheng Science and Technology on Thermostructural Composite Materials Laboratory Northwestern Polytechnical UniversityXi’an 710072China

To further improve the performance of binders,a SiHfBCN-based high-temperature resistant adhesive was successfully synthesized by Polymer-Derived Ceramics(PDC)route using TiB2,Polysiloxane(PSO)and short SiC nanowires as *** effect of short SiC nanowires on the adhesive strength at room temperature and high temperature,as well as the reinforcing mechanism was *** with the adhesive without SiC nanowires,after curing(at 170℃)and pyrolysis(at 1000℃)in air,the appropriate adding of SiC nanowires upgrades the room temperature and high temperature(at 1000℃ in air)adhesive strength to(12.50±0.67)MPa(up by about 32%)and(13.11±0.79)MPa(up by about 106%),***,under the synergistic impact of the nanowire bridging,nanowire breaking,nanowire drawing and crack deflection,the optimized adhesive exhibits multi-stage fracture,causing the increscent fracture displacement.

关键词： High-temperature resistant adhesive SiHfBCN SiC NWs Strengthening Toughening

Multiple Nanoparticles Coupling Strategy for Enhancing Optical Filter Performance of Spectral Splitter Used in Photovoltaic/Thermal System

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Journal of Thermal Science 2024年第1期33卷 368-382页

作者： LIANG Huaxu HUANG Xin WANG Fuqiang cheng Ziming dong Yan School of Energy Science and Engineering Harbin Institute of TechnologyHarbin 150001China School of New Energy Harbin Institute of Technology at WeihaiWeihai 264209China School of Materials Science and Engineering Nanyang Technological UniversitySingapore 639798Singapore

Selective absorptive nanofluid can pre-absorb certain sunlight wavelength that cannot be used by PV and transmits remaining sunlight to the surface of PV,which can decouple PV from the thermal receiver *** order to improve the harvesting of electricity and high-temperature thermal nanofluid,it is important to design an optimal optical filter window(transmit sunlight with wavelengths of 732-1067 nm to the surface of the photovoltaic cell and absorb the remaining sunlight).However,designing optimal optical filter is facing following challenges:(1) inherently narrow selective absorptivity property of single nanoparticle;(2) simplified numerical calculation method calculating transmittance;(3) ignoring the shape of the *** this study,the idea of using multiple nanoparticles coupling effect to design an optical filter is proposed,which can superimpose the narrow absorption bandwidth of different nanoparticles to obtain a wide absorption bandwidth of the whole *** addition,an improved transmission method considering light-matter interaction at air/vessel and liquid/vessel interfaces is adopted to compute the *** results calculated by improved transmission method are more accurate than widely used traditional Lambert-Beer law,which is verified by experimental ***,the effect of nanoparticle shape on spectral transmittance is also investigated,which shows that spiny Ag can approximately extend absorbance from 400 nm to 600 nm compared to nanosphere ***,the results show that optical filter efficiency of nanofluids with multiple nanoparticles coupling(Ag,spiny Ag,ZnO,ITO) can reached up to 35%.

关键词： solar energy PV/T nanofluid optimal optical filter radiative transfer spectral splitting

Rational design multi-color-emissive chemiluminescent carbon nanodots in a single solvothermal reaction

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Nano Research 2024年第6期17卷 4651-4660页

作者： Guang-Song zheng cheng-Long Shen Yuan Deng Kai-Kai Liu Jin-Hao Zang Lin dong Qing Lou Chong-Xin Shan Henan Key Laboratory of Diamond Optoelectronic Materials and Devices Key Laboratory of Materials PhysicsMinistry of Educationand School of Physics and MicroelectronicsZhengzhou UniversityZhengzhou 450052China

Recently,the chemiluminescence(CL)induced by carbon nanodots(CDs)has intrigued researchers’extensive interests in various applications due to its special light emission ***,the difficulty of synthesizing chemiluminescent CDs with full-spectrum emission severely hinders the further regulation of the CL emission ***,the multi-color-emissive chemiluminescent CDs are rational designed and further synthesized by regulating the sp2-hybrid core and sp3-hybrid surface from the citrate-ammonia molecular in a single solvothermal *** experimental characterizations and density functional theory calculations reveal that the higher temperature can promote the crosslinking polymerization/carbonization of carbon core and the higher protonation of solvent can determine the core size of final CDs,resulting in the variant CL emission from molecular-,crosslinking-and ***,the CL emission of the CDs can be further synthesized by tuning the luminescence chromophores in the formation process via regulating the temperature and solvent,enabling the applications of the CL CDs in illumination and information *** study paves a new technology to understand the luminescence of CDs and affords an industry translational potential over traditional chemiluminescent molecular.

关键词： carbon nanodots chemiluminescence regulation energy level alignment mechanism

A Novel Disturbance Observer Based Fixed-Time Sliding Mode Control for Robotic Manipulators With Global Fast Convergence

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IEEE/CAA Journal of Automatica Sinica 2024年第3期11卷 661-672页

作者： Dan Zhang Jiabin Hu Jun cheng zheng-Guang Wu Huaicheng Yan IEEE Zhejiang University of Technology Guangxi Normal University Zhejiang University the East China University of Science and Technology

This paper proposes a new global fixed-time sliding mode control strategy for the trajectory tracking control of uncertain robotic ***,a fixed-time disturbance observer(FTDO) is designed to deal with the adverse effects of model uncertainties and external disturbances in the manipulator *** an adaptive scheme is used and the adaptive FTDO(AFTDO) is developed,so that the priori knowledge of the lumped disturbance is not ***,a new non-singular fast terminal sliding mode(NFTSM) surface is designed by using an arctan function,which helps to overcome the singularity problem and enhance the robustness of the *** on the estimation of the lumped disturbance by the AFTDO,a fixed-time non-singular fast terminal sliding mode controller(FTNFTSMC)is developed to guarantee the trajectory tracking errors converge to zero within a fixed *** settling time is independent of the initial state of the *** addition,the stability of the AFTDO and FTNFTSMC is strictly proved by using Lyapunov ***,the fixed-time NFESM(FTNFTSM) algorithm is validated on a 2-link manipulator and comparisons with other existing sliding mode controllers(SMCs) are *** comparative results confirm that the FTNFTSMC has superior control performance.

关键词： Disturbance observer(DO) fixed-time non-singular sliding mode control robotic manipulator trajectory tracking

Comparison of prognosis and postoperative morbidities between standard pancreaticoduodenectomy and the TRIANGLE technique for resectable pancreatic ductal adenocarcinoma

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World Journal of Gastrointestinal Surgery 2024年第3期16卷 689-699页

作者： He-Xing Hang zheng-Hua Cai Yi-Fei Yang Xu Fu Yu-dong Qiu Hao cheng Division of Pancreatic Surgery Department of General SurgeryNanjing Drum Tower HospitalThe Affiliated Hospital of Medical SchoolNanjing UniversityNanjing 210008Jiangsu ProvinceChina

BACKGROUND Radical surgery combined with systemic chemotherapy offers the possibility of long-term survival or even cure for patients with pancreatic ductal adenocar-cinoma(PDAC),although tumor recurrence,especially locally,still inhibits the treatment *** TRIANGLE technique was introduced as an extended dissection procedure to improve the R0 resection rate of borderline resectable or locally advanced ***,there was a lack of studies concerning postoperative complications and long-term outcomes of this procedure on patients with resectable *** Patients with resectable PDAC eligible for PD from our hospital between June 2018 and December 2021 were enrolled in this retrospective cohort *** the patients were divided into PDstandard and PDTRIANGLE groups according to the surgical *** characteristics,surgical data,and postoperative morbidities were *** of the patients were followed up,and the date and location of tumor recurrence,and death were *** Kaplan-Meier method and log-rank test were used for the survival *** There were 93 patients included in the study and 37 underwent the TRIANGLE *** of operation was longer in the PDTRIANGLE group compared with the PDstandard group[440(410-480)min vs 320(265-427)min](P=0.001).Intraoperative blood loss[700(500-1200)mL vs 500(300-800)mL](P=0.009)and blood transfusion[975(0-1250)mL vs 400(0-800)mL](P=0.009)were higher in the PDTRIANGLE *** was a higher incidence of surgical site infection(43.2%vs 12.5%)(P=0.001)and postoperative diarrhea(54.1%vs 12.5%)(P=0.001)in the PDTRIANGLE *** rates of R0 resection and local recurrence,overall survival,and disease-free survival did not differ significantly between the two *** The TRIANGLE technique is safe,with acceptable postoperative morbidities compared with standardized PD,but it does not improve prognosis for patients with resectable PDAC.

关键词： Pancreatic ductal adenocarcinoma TRIANGLE technique Pancreaticoduodenectomy Prognosis Postoperative morbidities

Diagnosis and treatment of biliary mucinous cystic neoplasms: A single-center experience

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Hepatobiliary & Pancreatic Diseases International 2024年第5期23卷 495-501页

作者： Jun-Jun Jia Ya-Fen cheng Mei-Bao Feng Li Liu Ming-Qi Shuai Xiao-dong Shen Xiao-Feng Tang Shu-Sen zheng Division of Hepatobiliary and Pancreatic Surgery Department of Surgerythe First Affiliated HospitalZhejiang University School of MedicineHangzhou 310003China Department of International Healthcare Center the First Affiliated HospitalZhejiang University School of MedicineHangzhou 310003China Department of Pathology the First Affiliated HospitalZhejiang University School of MedicineHangzhou 310003China Department of Library the First Affiliated HospitalZhejiang University School of MedicineHangzhou 310003China

Background: Biliary mucinous cystic neoplasms(BMCNs) are rare hepatobiliary cystic tumors, which can be divided into noninvasive and invasive types. This study aimed to investigate the diagnosis, treatment, and prognosis of BMCNs in a large single center. Methods: We analyzed 49 patients with BMCNs confirmed by postoperative pathology at the First Afflliated Hospital, Zhejiang University School of Medicine between January 2007 and December 2021. Results: Among the 49 patients, 37 were female(75.5%), and the average age was 57.04 years. Common symptoms included abdominal discomfort, jaundice and fever, while 22 patients(44.9%) had no symptoms. Serum carbohydrate antigen(CA) 19-9 and CA125 concentrations were elevated in 34.8% and 19.6% of patients, respectively. Forty-eight patients had tumors in the intrahepatic bile ducts and only one had a tumor in the extrahepatic bile duct. Forty-eight patients with noninvasive intrahepatic BMCNs were further analyzed in terms of pathological features: 34(70.8%) had low-grade intraepithelial neoplasms(LGINs), and 14(29.2%) had high-grade intraepithelial neoplasms(HGINs). The potential immunohistochemical markers of BMCNs were cytokeratin(CK) 19, CK7, estrogen receptor and progesterone receptor. Follow-up data for 37 patients with intrahepatic BMCNs were obtained. The median overall survival(OS) of BMCNs was not reached. The longest survival time was 137 *** 5-and 10-year OS rates were 100% and 85.4%, respectively. The 5-and 10-year recurrence-free survival(RFS) rates were 93.9% and 80.2%, respectively. Conclusions: BMCNs are rare cystic neoplasms that commonly occur in middle-aged females. BMCNs can only be diagnosed and classified by postoperative pathology, as there are no specific clinical presentations, serological indicators or imaging modalities for preoperative diagnosis. Complete surgical resection is necessary for BMCNs, and the postoperative prognosis is favorable.

关键词： Biliary mucinous cystic neoplasms Low-grade intraepithelial neoplasms High-grade intraepithelial neoplasms Overall survival Recurrence-free survival

Design of new chemicals for advanced electrolytes

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Science China Chemistry 2024年第5期67卷 1378-1380页

作者： Haoran cheng zheng Ma Qian Li Jun Ming State Key Laboratory of Rare Earth Resource Utilization Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun130022China University of Science and Technology of China Hefei 230026China

This highlight is inspired by a recent article in Nature Energy in which Liu and co-workers [1] from Tsinghua University designed a new asymmetric lithium salt (i.e., lithium 1,1,1-trifluoro-N-[2-[2-(2-methoxy ethoxy)ethoxy]ethyl] methanesulfonamide (Li FEA)) and applied it as a new lithium-salt additive in the conventional carbonate-based electrolyte,overcoming the incompatibility issue of carbonate electrolytes with lithium metal in lithium metal batteries (LMBs),even achieving a fast-charging feature.

关键词： lithium carbonate electrolyte