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Optimal Design of Aperture Illuminations for Microwave Power Transmission with Annular Collection Areas

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Engineering 2023年第11期30卷 63-74页

作者： Xun LI Baoyan Duan Yiqun Zhang Yongxin Guo Shaanxi Key Laboratory of Space Solar Power Station System Xidian UniversityXi’an 710071China Department of Electrical and Computer Engineering National University of SingaporeSingapore 117576Singapore

This work presents an optimal design method of antenna aperture illumination for microwave power transmission with an annular collection area.The objective is to maximize the ratio of the power radiated on the annular collection area to the total transmitted power.By formulating the aperture amplitude distribution through a summation of a special set of series,the optimal design problem can be reduced to finding the maximum ratio of two real quadratic forms.Based on the theory of matrices,the solution to the formulated optimization problem is to determine the largest characteristic value and its associated characteristic vector.To meet security requirements,the peak radiation levels outside the receiving area are considered to be extra constraints.A hybrid grey wolf optimizer and Nelder–Mead simplex method is developed to deal with this constrained optimization problem.In order to demonstrate the effectiveness of the proposed method,numerical experiments on continuous apertures are conducted;then,discrete arrays of isotropic elements are employed to validate the correctness of the optimized results.Finally,patch arrays are adopted to further verify the validity of the proposed method.

关键词： Microwave power transmission Beam collection efficiency Ring-shaped beam Annular collection area Grey wolf optimizer Nelder-Mead simplex method

Inhibition of Cyclin F Promotes Cellular Senescence through Cyclin-dependent Kinase 1-mediated Cell Cycle Regulation

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Current Medical Science 2023年第2期43卷 246-254页

作者： Xun LI You-jian li Meng-jie WANG Ke-peng OU Ya-qi CHEN GI Cancer Research Institute Tongji HospitalHuazhong University of Science and TechnologyWuhan430030China College of Pharmacy National&Local Joint Engineering Research Center of Targeted and Innovative TherapeuticsChongqing Key Laboratory of Kinase Modulators as Innovative MedicineChongqing University of Arts and SciencesChongqing402160China Department of Obstetrics and Gynecology Tongji HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhan430030China College of Pharmaceutical Sciences and Chinese Medicine Southwest UniversityChongqing400715China

Objective Kidney renal clear cell carcinoma(KIRC)is a common renal malignancy that has a poor prognosis.As a member of the F box family,cyclin F(CCNF)plays an important regulatory role in normal tissues and tumors.However,the underlying mechanism by which CCNF promotes KIRC proliferation still remains unclear.Methods Bioinformatics methods were used to analyze The Cancer Genome Atlas(TCGA)database to obtain gene expression and clinical prognosis data.The CCK8 assay,EdU assay,and xenograft assay were used to detect cell proliferation.The cell senescence and potential mechanism were assessed by SA-β-gal staining,Western blotting,as well as EliSA.Results Our data showed that CCNF was highly expressed in KIRC patients.Meanwhile,downregulation of CCNF inhibited cell proliferation in vivo and in vitro.Further studies showed that the reduction of CCNF promoted cell senescence by decreasing cyclin-dependent kinase 1(CDK1),increasing the proinflammatory factors interleukin(IL)-6 and IL-8,and then enhancing the expression of p21 and p53.Conclusion We propose that the high expression of CCNF in KIRC may play a key role in tumorigenesis by regulating cell senescence.Therefore,CCNF shows promise as a new biomarker to predict the clinical prognosis of KIRC patients and as an effective therapeutic target.

关键词： cyclin F kidney renal clear cell carcinoma clinical outcome cyclin-dependent kinase 1 senescence

Survey on Multi-period Mean-Variance Portfolio Selection Model

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Journal of the Operations Research Society of China 2022年第3期10卷 599-622页

作者： Xiang-Yu Cui Jian-Jun Gao Xun LI Yun Shi School of Statistics and Management Shanghai University of Finance and EconomicsShanghai200433China School of Information Management and Engineering Shanghai University of Finance and EconomicsShanghai200433China Department of Applied Mathematics The Hong Kong Polytechnic UniversityHong KongChina Academy of Statistics and Interdisciplinary Sciences Faculty of Economics and ManagementEast China Normal UniversityShanghai200062China

Due to the non-separability of the variance term,the dynamic mean-variance(MV)portfolio optimization problem is inherently difficult to solve by dynamic programming.li and Ng(Math Finance 10(3):387-406,2000)and Zhou and li(Appl Math Optim 42(1):19-33,2000)develop the pre-committed optimal policy for such a problem using the embedding method.Following this line of research,researchers have extensively studied the MV portfolio selection model through the inclusion of more practical investment constraints,realistic market assumptions and various financial applications.As the principle of optimality no longer holds,the pre-committed policy suffers from the time-inconsistent issue,i.e.,the optimal policy computed at the intermediate time t is not consistent with the optimal policy calculated at any time before time t.The time inconsistency of the dynamic MV model has become an important yet challenging research topic.This paper mainly focuses on the multi-period mean–variance(MMV)portfolio optimization problem,reviews the essential extensions and highlights the critical development of time-consistent policies.

关键词： Multi-period mean-variance Investment constraints Time inconsistency

Isospin effects on intermediate mass fragments at intermediate energy-heavy ion collisions

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Nuclear Science and Techniques 2022年第5期33卷 68-77页

作者： li li Fang-Yuan Wang Ying-xun Zhang China Institute of Atomic Energy P.O.Box 275(18)Beijing 102413China Department of Physics and Technology Guangxi Normal UniversityGuilin 540101China

In this study,we investigated the isospin properties of intermediate mass fragments(IMFs)for the central collisions of^(112,124)Sn+^(112,124)Sn at a beam energy of50 MeV per nucleon using an improved quantum molecular dynamics model(ImQMD)coupled with a sequential decay model(GEMINI).Three observables were analyzed:(1)the average center-of-mass kinetic energy per nucleonof fragments as a function of their charge number Z;(2)the average neutron number to proton number ratio(/Z)of fragments with a given charge number Z as a function of their center-of-mass kinetic energy per nucleon(Ec.m./A);and(3)the average total neutron number to total proton number ratio(ΣN/ΣZ)and double ratio(DR(N/Z))of IMFs with Z=3-8 as a function of their center-of-mass kinetic energy per nucleon Ec.m./A.Our calculations revealed that the sensitivity of the isospin properties of IMFs relative to the stiffness of the symmetry energy remains even after sequential decay.By comparing the calculations ofΣN/ΣZ and DR(N/Z)with the data,it was found that the soft symmetry energy,i.e.,γ=0.5,is favored.

关键词： Symmetryenergy Intermediatemass fragments Isospin effects

Nitrogen slow-release behavior of oxamide granules in two different types of paddy soils

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Pedosphere 2022年第6期32卷 856-865页

作者： Xun LI Jinlong DONG Jingjing DUAN Wenzhong SHEN Zengqiang DUAN State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil ScienceChinese Academy of SciencesNanjing 210008(China) School of the Environment and Safety Engineering Jiangsu UniversityZhenjiang 212013(China) Agricultural Technology Promotion Center Taicang Agriculture CommitteeSuzhou 215400(China)

Oxamide is a potential slow-release nitrogen(N)fertilizer,especially under waterlogged conditions,due to its low solubility in water and the slow-release of ammonium by soil amidases.To investigate the effects of oxamide granules(2.00-2.38 mm in diameter)as a single basal fertilizer(180 or 144 kg N ha^(-1))on rice growth,soil properties,and N use efficiency in terms of N recovery efficiency(NRE),we conducted field experiments on two different types of paddy soils over two rice-growing seasons.Results showed that the fertilization effects of oxamide granules varied between the two types of paddy soils.In the red clayey paddy soil,the grain yields for both rice-growing seasons were high with a significantly higher NRE in the oxamide treatment than in the urea treatment.However,in the alluvial sandy paddy soil,the grain yields in the oxamide treatment were slightly lower than those in the urea treatment.Furthermore,oxamide produced little improvement in NRE in the alluvial sandy paddy soil.Soil incubation experiments over 98 d were also carried out to evaluate the factors affecting the N release behavior of oxamide granules in the two types of paddy soils.We found that the amidase activity was higher and,therefore,the oxamide hydrolysis rate was faster in the alluvial sandy paddy soil,which had a higher soil pH value and organic matter content,compared to the red clayey paddy soil.The faster N release and the longer growth period resulted in a mismatch between N supply by oxamide and rice demand,which,in turn,led to little improvement in NRE and a decreased grain yield in the alluvial sandy paddy soil,especially in the reduced oxamide treatment.These results could help select the appropriate size of oxamide granules for use as a slow-release N fertilizer depending on the soil properties and growth period of rice.

关键词： amidase activity grain yield nitrogen use efficiency organic matter content pH slow-release fertilizer

Influences of milling and grinding on machined surface roughness and fatigue behavior of GH4169 superalloy workpieces

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Chinese Journal of Aeronautics 2018年第6期31卷 1399-1405页

作者： Xun LI Chunming GUAN Peng ZHAO School of Mechanical Engineering and Automation Beihang University

Surface topography of superalloy GH4169 workpieces machined by milling and grinding is different significantly. Meanwhile, surface roughness, as one of the main indicators of machined surface integrity, has a great influence on the fatigue behavior of workpieces. Based on analyzing the formation mechanism and characteristics of surface roughness utilizing different machining processes and parameters, the machined surface roughness curve can be decoupled into two parts utilizing frequency spectrum analysis, which are kinematic surface roughness curve and stochastic surface roughness curve. The kinematic surface roughness curve is influenced by machining process,parameters, geometry of the cutting tool or wheel, the maximum height of which is expressed as Rz＇.By subtracting the kinematic part from the measurement curve, the stochastic surface roughness curve and its maximum height Rz＂ can be obtained, which is influenced by the defects of cutting tool edge or abrasive grains, built-up edges（BUE）, cracks, high frequency vibration and so on. On the other hand, the results of decoupling analysis of surface roughness curves indicate that Raand Rz values of milling GH4169 are 2–5 times and 1–3 times as high as those of grinding, while Rz＂ value of milling is 13.85%–37.7% as high as that of grinding. According to the results of fatigue life tests of specimens machined by milling and grinding, it can be concluded that fatigue behavior of GH4169 decreases with the increase of Rz＂monotonically, even utilizing different machining processes.

关键词： Fatigue life GH4169 Grinding Milling Surface integrity

Effects of Number of Bleed Holes on Shock-Wave/Boundary-Layer Interactions in a Transonic Compressor Stator

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Journal of Thermal Science 2024年第2期33卷 611-624页

作者： li Bai ZHOU xun LUO Lei DU Wei School of Energy Science and Engineering Harbin Institute of TechnologyHarbin150001China

An extensive numerical investigation is conducted to characterize the flow separation control in a transonic compressor cascade with a porous bleed.The bleed holes are arranged on the suction surface in a single row,two staggered rows and three staggered rows.For each bleed scheme,five bleed pressure ratios are examined at an inlet Mach number of 1.0.The results indicate that the aerodynamic performance of the cascade is significantly improved by the porous bleed.For the single-row scheme,the maximum reduction in total pressure losses is 57%.For the two-staggered-row and three-staggered-row schemes,there is an optimal bleed pressure ratio of 1.0,and the maximum reductions in total pressure loss are 68% and 75%,respectively.The low loss in the cascade is due to the well-controlled boundary layer.The new local supersonic region created by the bleed hole is the key reason for the improved boundary layer.The vortex induced by side bleeding provides another mechanism for delaying flow separation.Increasing the bleed holes could create multiple local supersonic regions,which reduce the range of the adverse pressure gradient that the boundary layer needs to withstand.This is the reason why cascades with more bleed holes perform better.

关键词： transonic compressor stator shock wave/boundary layer interaction porous bleed number of bleed holes

Brain protective effect of dexmedetomidine vs propofol for sedation during prolonged mechanical ventilation in non-brain injured patients

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World Journal of Psychiatry 2024年第3期14卷 370-379页

作者： Hong-xun Yuan li-Na Zhang Gang li li Qiao Intensive Care Unit Peking University International HospitalBeijing 102206China Central Operating Room The Affiliated Beijing Chaoyang Hospital of Capital Medical UniversityBeijing 100020China

BACKGROUND Dexmedetomidine and propofol are two sedatives used for long-term sedation.It remains unclear whether dexmedetomidine provides superior cerebral protection for patients undergoing long-term mechanical ventilation.AIM To compare the neuroprotective effects of dexmedetomidine and propofol for sedation during prolonged mechanical ventilation in patients without brain injury.METHODS Patients who underwent mechanical ventilation for>72 h were randomly assigned to receive sedation with dexmedetomidine or propofol.The Richmond Agitation and Sedation Scale(RASS)was used to evaluate sedation effects,with a target range of-3 to 0.The primary outcomes were serum levels of S100-βand neuron-specific enolase(NSE)every 24 h.The secondary outcomes were remifentanil dosage,the proportion of patients requiring rescue sedation,and the time and frequency of RASS scores within the target range.RESULTS A total of 52 and 63 patients were allocated to the dexmedetomidine group and propofol group,respectively.Baseline data were comparable between groups.No significant differences were identified between groups within the median duration of study drug infusion[52.0(IQR:36.0-73.5)h vs 53.0(IQR:37.0-72.0)h,P=0.958],the median dose of remifentanil[4.5(IQR:4.0-5.0)μg/kg/h vs 4.6(IQR:4.0-5.0)μg/kg/h,P=0.395],the median percentage of time in the target RASS range without rescue sedation[85.6%(IQR:65.8%-96.6%)vs 86.7%(IQR:72.3%-95.3),P=0.592],and the median frequency within the target RASS range without rescue sedation[72.2%(60.8%-91.7%)vs 73.3%(60.0%-100.0%),P=0.880].The proportion of patients in the dexmedetomidine group who required rescue sedation was higher than in the propofol group with statistical significance(69.2%vs 50.8%,P=0.045).Serum S100-βand NSE levels in the propofol group were higher than in the dexmedetomidine group with statistical significance during the first six and five days of mechanical ventilation,respectively(all P<0.05).CONCLUSION Dexmedetomidine demonstrated stronger protective effects on the brain compare

关键词： Dexmedetomidine Propofol Sedation Prolonged mechanical ventilation Brain protective

Perspective on new cell-free DNA technologies for early cancer detection

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Cancer Biology & Medicine 2024年第2期21卷 139-143页

作者： Jie li xun Lan Department of Basic Medical Sciences School of MedicineTsinghua UniversityBeijing 100084China MOE Key Laboratory of Bioinformatics Tsinghua UniversityBeijing 100084China Tsinghua-Peking Joint Center for life Sciences Tsinghua UniversityBeijing 100084China

High cancer heterogeneity and aggressiveness are major factors contributing to the poor prognosis of patients with advanced cancer~(1-5).Early detection of cancer can significantly improve the prognosis of patients with early-stage cancer after standard treatment.Although traditional cancer detection technologies,such as endoscopy for gastrointestinal cancer,mammography for breast cancer。

关键词： prognosis cancer patients