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A 16-competitive algorithm for hierarchical median problem

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Science China(Information Sciences) 2014年第3期57卷 147-153页

作者： dai WenQiang School of Management and Economics University of Electronic Science and Technology of China

The hierarchical median problem consists of finding a hierarchical assignment function sequence of solutions to the well-known k-median problems with growing *** sequence is said to be rcompetitive if the cost of each solution is at most r-times of the optimum cost of median problem with a same cardinality,where r is called the competitive *** the best algorithm available for this problem has competitive ratio *** this paper an improved algorithm is proposed with competitive ratio factor 16.

关键词： hierarchical location median algorithm competitive ratio

Asymptotic Behavior of Global Classical Solutions of Quasilinear Non-strictly Hyperbolic Systems with Weakly Linear Degeneracy

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Chinese Annals of Mathematics,Series B 2006年第3期27卷 263-286页

作者： Wenrong dai Department of Mathematics Shanghai Jiao Tong University Shanghai 200240 China.

In this paper, we study the asymptotic behavior of global classical solutions of the Cauchy problem for general quasilinear hyperbolic systems with constant multiple and weakly linearly degenerate characteristic fields. Based on the existence of global classical solution proved by Zhou Yi et al., we show that, when t tends to infinity, the solution approaches a combination of C^1 travelling wave solutions, provided that the total variation and the L^1 norm of initial data are sufficiently small.

关键词： Asymptotic behavior Characteristic fields with constant multiplicity,Weakly linear degeneracy Global classical solution Normalized coordinates Travelling wave

超碱NLi_(4)团簇修饰DHQ石墨烯的储氢性能研究

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原子与分子物理学报 2025年第5期42卷 95-101页

作者：戴小乐王允辉黄欣南京邮电大学电子与光学工程学院柔性电子(未来技术)学院南京210023 南京邮电大学理学院南京210023

基于第一性原理计算,系统研究了超碱NLi_(4)团簇修饰在DHQ石墨烯表面上的几何结构及吸附能等性质,并深入探索了其储氢性能.研究结果表明:超碱NLi_(4)团簇可以稳定均匀地吸附在DHQ石墨烯表面,Li原子与N原子的强结合能有效避免了Li原子发... 详细信息

基于第一性原理计算,系统研究了超碱NLi_(4)团簇修饰在DHQ石墨烯表面上的几何结构及吸附能等性质,并深入探索了其储氢性能.研究结果表明:超碱NLi_(4)团簇可以稳定均匀地吸附在DHQ石墨烯表面,Li原子与N原子的强结合能有效避免了Li原子发生团聚.每个NLi_(4)团簇周围最多可吸附11个氢气分子,平均吸附能为0.20 eV,最大储氢容量为12.05 wt%,达到美国能源部制定的2025年储氢目标5.5 wt%.最后,基于相对能量计算,发现当压强大于84 bar时,该储氢体系可以在室温下稳定存在.以上结果表明经超碱NLi_(4)团簇修饰的DHQ石墨烯是一种有潜力的储氢材料.

关键词：多孔材料储氢超碱NLi_(4)团簇 DHQ石墨烯第一性原理计算

Kinetics of testosterone recovery in clinically localized prostate cancer patients *** radical prostatectomy and subsequent short-term adjuvant androgen deprivation therapy

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Asian Journal of Andrology 2013年第4期15卷 466-470,I0006页

作者： Bo dai Department of Urology Fudan University Shanghai Cancer Center Shanghai 200032 China Department of Oncology Fudan University Shanghai Medical College Shanghai 200032 China and Department of Pathology Fudan University Shanghai Cancer Center Shanghai 200032 China

deprivation therapy （ADT） is a standard treatment for metastatic, recurrent and locally advanced prostate cancer （PCa）. The aim of this study is to investigate the timing and extent of testosterone recovery in clinically localized PCa patients treated with radical prostatectomy （RP） and subsequent short-term adjuvant ADT. A total of 95 localized PCa patients underwent RP and 9-month adjuvant ADT were included in this prospective study. Serum testosterone level was measured before adjuvant ADT, at ADT cessation, and at 1, 3, 6, 9 and 12 months after cessation of ADT. A Cox proportional hazards model was used to assess variables associated with the ti me of testosterone normalization. The results showed that median patient age was 67 years and median testosterone level before adjuvant ADT was 361 （230-905） ng d1-1. All patients finished 9-month adjuvant ADT and achieved castrate testosterone level. At 3 months after ADT cessation, testosterone recovered to supracastrate level in 97.9% patients and to normal level in 36.9% patients. The percentage of patients who recovered to normal testosterone level increased to 66.3%, 86.3% and 92.6% at 6, 9 and 12 months, respectively. Cox regression model found that higher baseline testosterone level （ 300 ng dl- 1） was the only variable associated with a shorter time to testosterone normalization （hazard ratio： 1.98; P -- 0.012）. In conclusion, in most patients, testosterone recovered to supracastrate level at 3 months and to normal level at 12 months after 9-month adjuvant ADT cessation. Patients with higher baseline testosterone level need shorter time of testosterone normalization.

关键词： androgen deprivation therapy (ADT) luteinizing hormone-releasing hormone prostatic neoplasms recovery of function testosterone

Calibration method of phase distortions for cross polarization channel of instantaneous polarization radar system

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Journal of Systems Engineering and Electronics 2010年第2期21卷 211-218页

作者： Huanyao dai Yuliang Chang Dahai dai Yongzhen Li XuesongWang School of Electronic Science and Engineering National University of Defense Technology Changsha 410073 R R. China

A novel polarimetric calibration method for new target property measurement radar system is presented. Its applica- tion in the real radar system is also discussed. The analysis indicates that instantaneous polarization radar （[PR） has inherent cross-polarization measurement error. The proposed method can effectively eliminate this error, and thus enhance the polarization scattering matrix （PSM） measurement precision. The phase error caused by digital receiver＇s direct IF sampling and mixing of two orthogonal polarization channels can be removed. Consequently, the inherent error of target polarization scattering measurement of the instantaneous polarization radar system is well revised. It has good reference value for further ploarimetric calibration and high practical application prospect.

关键词： instantaneous polarization radar target scattering ma- trix (PSM) polarization measurement polarimetric calibration.

Seismic performance evaluation of water supply pipes installed in a full-scale RC frame structure based on a shaking table test

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Earthquake Engineering and Engineering Vibration 2024年第1期23卷 163-178页

作者： Wu Houli Guo Endong Wang Jingyi dai Xin dai Chenxi Key Laboratory of Earthquake Engineering and Engineering Vibration Institute of Engineering MechanicsChina Earthquake AdministrationHarbin 150080China Key Laboratory of Earthquake Disaster Mitigation Ministry of Emergency ManagementHarbin 150080China

As an important part of nonstructural components,the seismic response of indoor water supply pipes deserves much *** paper presents shaking table test research on water supply pipes installed in a full-scale reinforced concrete(RC)frame *** material pipes and different methods for penetrating the reinforced concrete floors are combined to evaluate the difference in seismic *** response spectra and pipe acceleration amplification factors based on test data are discussed and compared with code provisions.A seismic fragility study of displacement demand is conducted based on numerical *** acceleration response and displacement response of different combinations are *** results show that the combination of different pipe materials and different passing-through methods can cause obvious differences in the seismic response of indoor riser pipes.

关键词： water supply pipe different materials shaking table test amplification factor seismic fragility

Heavy Traffic Limit Theorems for a Queue with Poisson ON/OFF Long-range Dependent Sources and General Service Time Distribution

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Acta Mathematicae Applicatae Sinica 2012年第4期28卷 807-822页

作者： Wan-yang dai Department of Mathematics and State Key Laboratory of Novel Software TechnologyNanjing University

In Internet environment, traffic flow to a link is typically modeled by superposition of ON/OFF based sources. During each ON-period for a particular source, packets arrive according to a Poisson process and packet sizes （hence service times） can be generally distributed. In this paper, we establish heavy traffic limit theorems to provide suitable approximations for the system under first-in first-out （FIFO） and work-conserving service discipline, which state that, when the lengths of both ON- and OFF-periods are lightly tailed, the sequences of the scaled queue length and workload processes converge weakly to short-range dependent reflecting Gaussian processes, and when the lengths of ON- and/or OFF-periods are heavily tailed with infinite variance, the sequences converge weakly to either reflecting fractional Brownian motions （FBMs） or certain type of long- range dependent reflecting Gaussian processes depending on the choice of scaling as the number of superposed sources tends to infinity. Moreover, the sequences exhibit a state space collapse-like property when the number of sources is large enough, which is a kind of extension of the well-known Little＇s law for M/M/1 queueing system. Theory to justify the approximations is based on appropriate heavy traffic conditions which essentially mean that the service rate closely approaches the arrival rate when the number of input sources tends to infinity.

关键词： reflecting fractional Brownian motion reflecting Gaussian process long-range dependence queueing process weak convergence

Stresses due to an adhesion crack in T-shaped junction of two orthotropic plates

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Acta Mechanica Sinica 2012年第2期28卷 419-423页

作者： dai-Heng Chen Department of Mechanical Engineering Tokyo University of Science 1-3 KagurazakaShinjuku-ku Tokyo 162-8601 Japan

The general solution of stresses is derived for a T-shaped junction of two thin plates with an adhesion crack. The plates are orthotropic. A shear force is applied on the crack surface. The analysis is based on the supposition that the stresses in each plate can be approximated by a plane stress condition. The results obtained are verified by numerical calculation of FEM.

关键词： Elasticity Crack Thin plate T-shaped Junc-tion Hilbert Problem

Designing nonlinear thermal devices and metamaterials under the Fourier law: A route to nonlinear thermotics

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Frontiers of physics 2021年第5期16卷 107-142页

作者： Gao-Le dai School of Sciences Nantong UniversityNantong226019China

Nonlinear heat transfer can be exploited to reveal novel transport phenomena and thus enhance people’s ability to manipulate heat flux at ***,there has not been a mature discipline called nonlinear thermotics like its counterpart in optics or acoustics to make a systematic summary of relevant *** the current review,we focus on recent progress in an important part of nonlinear heat transfer,i.e.,tailoring nonlinear thermal devices and metamaterials under the Fourier law,especially with temperature-dependent thermal *** will present the basic designing techniques including solving the equation directly and the transformation *** nonlinearity coming from multi-physical effects,and how to calculate effective properties of nonlinear conductive composites using the effective medium theory are also *** on these theories,researchers have successfully designed various functional materials and devices such as the thermal diodes,thermal transistors,thermal memory elements,energy-free thermostats,and intelligent thermal materials,and some of them have also been realized in ***,these phenomenological works can provide a feasible route for the development of nonlinear thermotics.

关键词： nonlinear thermotics thermal metamaterials thermal conduction thermal radiation thermal convection thermo-mechanical effects effective medium theory