海上结构物的Ringing现象

介绍近年来新发现的海上结构物在高海况下遇到的一种现象─—ringing高频共振响应现象及这一现象现有的研究成果，包括该现象的发现过程、特征、产生的机理及研究方法等。提出了研究ringing现象的一种可能的新方法。

Two phenomena: Honji instability, and ringing of offshore structures

Honji instability and ringing of offshore structrures are two different phenomena. Honji instability occurs at a circular cylinder in transverse periodic finite motion in a water tank. It is superposed on the streaming flow induced by the cylinder’s boundary layer. Its oscillation period is half of the period of the cylinder oscillation. Finite volume calculations of the filtered Navier-Stokes equations visualize the three-dimensional instability, where fluid particles transported by the circumferencial roll pairs exhibit a periodic mushroom-like pattern. Force is the same with and without the Honji instability. The large eddy simulation calculations for high Reynolds number support a drag coefficient in accordance with the Stokes-Wang solution below separation and conform with experimental measurements of the damping force on a harmonically oscillating cylinder. Ringing of offshore structures are vibrations which appear at natural frequencies and concern fatigue. It is generated by a higher harmonic force oscillating with frequency being 3-4 times the fundamental wave frequency. Together with a strong inertia load in phase with the incoming wave’s acceleration, a secondary load cycle appears in strong seas when the wave crest leaves the structure; this occurs about 1/4 wave period after the main force peak, it starts when the wave crest is about one cylinder radius behind the cylinder, lasts for about 15-20 percent of the wave period and has a magnitude up to 11 % of the peak-to-peak total force. It is a gravity effect and appears in strong irregular seas when kA > 0.18 and um/√gD > 0.4 (k wavenumber, A amplitude, um maximal wave induced velocity, g acceleration of gravity, D cylinder diameter).

Multiscale anisotropic diffusion for ringing artifact suppression in geophysical deconvolution data

Ringing artifact degradations always appear in the deconvolution of geophysical data. To address this problem, we propose a postprocessing approach to suppress ringing artifacts that uses a novel anisotropic diffusion based on a stationary wavelet transform （SWT） algorithm. In this paper, we discuss the ringing artifact suppression problem and analyze the characteristics of the deconvolu- tion ringing artifact. The deconvolution data containing ringing artifacts are decomposed into different SWT sub- bands for analysis, and a new multiscale adaptive aniso- tropic filter is developed to suppress these degradations. Finally, we demonstrate the performance of the proposed method and describe the experiments in detail.

Numerical Study of the High-Frequency Wave Loads and Ringing Response of A Bottom-Hinged Vertical Cylinder in Focused Waves

This paper presents a numerical study on the high-frequency wave loads and ringing response of offshore wind turbine foundations exposed to moderately steep transient water waves.Input wave groups are generated by the technique of frequency-focusing,and the numerical simulation of focused waves is based on the NewWave model and a Fourier time-stepping procedure.The proposed model is validated by comparison with the published laboratory data.In respect of both the wave elevations and the underlying water particle kinematics,the numerical results are in excellent agreement with the experimental data.Furthermore,the local evolution of power spectra and the transfer of energy into higher frequencies can be clearly identified.Then the generalized FNV theory and Rainey’s model are applied respectively to calculate the nonlinear wave loads on a bottom-hinged vertical cylinder in focused waves.Resonant ringing response excited by the nonlinear high-frequency wave loads is found in the numerical simulation when frequency ratios(natural frequency of the structure to peak frequency of wave spectra)are equal to 3–5.Dynamic amplification factor of ringing response is also investigated for different dynamic properties(natural frequency and damping ratio)of the structure.

Object Picture of Electromagnetic Quasinormal Ringing for a Stringy Black Hole

We investigate the evolution of an electromagnetic field in the spacetime of a stringy black hole.The objectpicture of the quasinormal ringing has been obtained by the finite difference method.Compared with a Schwarzschildblack hole,the results show that the electromagnetic field damps more slowly for a stringy black hole.

Prevalence of Ringing Delusion among Mobile Phone Users

The exponential application of mobile technology has led to a concern about implications of electromagnetic radiation on human health. As we are aware that mobile phone radiates EMR when users communicate to others and that time subscribers of the device are regularly exposed nearby 40% - 50% of total mobile irradiation. We analyzed the risk of "Ringing Delusion" among normal users, moderate users and heavy users when compared to low users. Although the "Ringing Delusion" has not been added in medical terminology but we found frequently such kind of symptoms among mobile phone users. "Ringing Delusion" may be considered as an imagination of ringing voice from cellular phone. The risk was also compared between urban and rural, male and female and adult and children population. The information was gathered through well designed questionnaires for cellular user’s demographic and social characteristics, adopted safety measures and calling duration. Prevalence of “Ringing Delusion” among rural users was higher than the urban users. A trend for the risk was also observed in male users in comparison to female. Study may support innovators to re-examine health effects of mobile phones.

Ringing cancellation in Carr-Purcell-Meiboom-Gill-type sequences

We propose a four-step phase cycling scheme that can cancel ringings from both the excitation and the refocusing pulses in Carr-Purcell-Meiboom-Gill(CPMG)measurements.It allows accurate measurements of the first echo with short echo spacing tE,yielding improved precision of porosity,permeability,and fluid type identification in porous media study,at a cost of~25%signal reduction.In our example,we achieved tE=100 ms on a 6.8 MHz unilateral NMR sensor without using a Q-switch.These methods can be integrated in all nuclear magnetic resonance(NMR)protocols using CPMG,such as relaxation(T1,T2)and diffusion measurements,and do not require additional hardware(e.g.,Qswitches)to cancel ringing(although it can be used with a Q-switch to further reduce residual ringing).

Online Tills Ringing Out

A LAPTOP, a broadband connection and a pile of express delivery orders are all clues that 26-year-old Qu Wen was no longer a member of the nine-to-five white collar brigade. Three years after graduating, 0u now manages an online store on Taobao, China＇s fast-growing online shopping bazaar, selling handbags, cosmetics, accessories and other goods. Her online store now has three employees, and daily turnover surpassing 10,000 yuan （$1.612）. Last year. the entrepreneur also opened a retail outlet in her hometown in Shandong Province.

Investment Bells Ringing

It＇s just been over half a year since Kenya inaugurated its standard gauge railway, but already the transport system is seeing heavy demand from travelers between Nairobi and Mombasa.

Africa Is Ringing in the Changes

Sales show that Chinese mobile phone manufacturers have dialed into what African consumers really need by Gui Gui WHEN Guan Yazhou visited Tanzania’s Kariakoo market for the first time in late 2009,he couldn’t help but be impressed.Today,the 29-year-old mobile phone engineer can still remember how surprised he was at seeing the extent to which Tecno,a Chinese mobile phone brand,had blanketed the area in advertising material.

Ringing in the Changes Unprecedented State Council restructuring sees creation, cuts and merges of ministries

China＇s Xinhua News Agency calls it the ＂biggest government reshuffle in years＂ in what is seen as a dra matic continuation of the previous seven rounds of cabinet restructuring that began in 1982.

Ringing spectroscopy in the magnomechanical system

The ringing phenomenon has been studied in optical whispering gallery mode(WGM)resonators and can be used to sense the ultrafast process in spectroscopy.Here we observe the ringing phenomenon in a magnomechanical system for the first time,which is induced by the interference between the microwave photons converted from the damped phonons and the probing microwave photons.This interference eventually appears as a transparency window even along with the ringing phenomenon in the measured microwave reflection spectrum,which is influenced by the scanning speed and the input power.Then,the ringing spectroscopy is used to measure the coupling strength between the magnon and phonon modes,and outline the displacement profile of𝑆1,2,2 mechanical mode in a YIG microsphere,demonstrating the theoretical analysis.In addition,the ring-up spectroscopy is developed in our magnomechanical system,laying the foundation for fast sensing based on mechanical motion.

A 16-bit 18-MSPS flash-assisted SAR ADC with hybrid synchronous and asynchronous control logic

This paper presents a 16-bit,18-MSPS(million samples per second)flash-assisted successive-approximation-register(SAR)analog-to-digital converter(ADC)utilizing hybrid synchronous and asynchronous(HYSAS)timing control logic based on an on-chip delay-locked loop(DLL).The HYSAS scheme can provide a longer settling time for the capacitive digital-to-analog converter(CDAC)than the synchronous and asynchronous SAR ADC.Therefore,the issue of incomplete settling or ringing in the DAC voltage for cases of either on-chip or off-chip reference voltage can be solved to a large extent.In addition,the fore-ground calibration of the CDAC’s mismatch is performed with a finite-impulse-response bandpass filter(FIR-BPF)based least-mean-square(LMS)algorithm in an off-chip FPGA(field programmable gate array).Fabricated in 40-nm CMOS process,the proto-type ADC achieves 94.02-dB spurious-free dynamic range(SFDR),and 75.98-dB signal-to-noise-and-distortion ratio(SNDR)for a 2.88-MHz input under 18-MSPS sampling rate.

Finesse measurement for high-power optical enhancement cavity

Finesse is a critical parameter for describing the characteristics of an optical enhancement cavity(OEC). This paper first presents a review of finesse measurement techniques, including a comparative analysis of the advantages, disadvantages, and potential limitations of several main methods from both theoretical and practical perspectives. A variant of the existing method called the free spectral range(FSR) modulation method is proposed and compared with three other finesse measurement methods, i.e., the fast-switching cavity ring-down(CRD) method, the rapidly swept-frequency(SF) CRD method, and the ringing effect method. A high-power OEC platform with a high finesse of approximately 16000 is built and measured with the four methods. The performance of these methods is compared, and the results show that the FSR modulation method and the fast-switching CRD method are more suitable and accurate than the other two methods for high-finesse OEC measurements. The CRD method and the ringing effect method can be implemented in open loop using simple equipment and are easy to perform. Additionally, recommendations for selecting finesse measurement methods under different conditions are proposed, which benefit the development of OEC and its applications.

分布式机器学习网络通信优化技术

Ring all-reduce算法被广泛应用在分布式机器学习之中,其同步过程会受到慢节点的影响进而降低整个系统的效率。对Ring all-reduce中的Reduce_Scatter和Allgather 2个阶段进行分析,针对Reduce_Scatter数据汇总过程提出优化策略,其主要思想是将慢节点多出的计算时间与通信时间进行重叠。使用OMNet++对Ring all-reduce和优化策略进行对比仿真,仿真结果与理论分析相一致,该策略相比Ring all-reduce算法最高能缩短25.3%的训练时间。

Experimental,Numerical,and Analytical Studies on the Bending of Mechanically Lined Pipe

Mechanically lined pipe(MLP)is often used for offshore oil and gas transport because of its low cost and corrosion resistance.During installation and operation,the pipe may undergo severe bending deformation,which causes the liner to separate from the outer pipe and buckles,affecting the stability of the whole line.In this paper,the buckling response of MLP subjected to bending is investigated to clarify its bending characteristics by employing both experiments,numerical simulation,as theoretical methods.Two types of MLPs were manufactured with GB 45 carbon steel(SLP)and Al 6061(ALP)used as the outer pipe material,respectively.The hydraulic expansion and bending experiments of small-scale MLPs are conducted.In addition to the ovalized shape of the cross-section for the SLP specimens,the copper liner was found to wrinkle on the compressive side.In contrast,the liner of ALP remains intact without developing any wrinkling and collapse mode.In addition,a dedicated numerical framework and theoretical models were also established.It was found both the manufacturing and bending responses of the MLP can be well reproduced,and the predicted maximum moment and critical curvatures are in good agreement with the experimental results.

Rising utilization of stable isotopes in tree rings for climate change and forest ecology

Analyses of stable isotopes(C,O,H)in tree rings are increasingly important cross-disciplinary programs.The rapid development in this field documented in an increasing number of publications requires a comprehensive review.This study includes a bibliometric analysis-based review to better understand research trends in tree ring stable isotope research.Overall,1475 publications were selected from the Web of Science Core Collection for 1974-2023.The findings are that:(1)numbers of annual publications and citations increased since 1974.From 1974 to 1980,there were around two relevant publications per year.However,from 2020 to 2022,this rose sharply to 109 publications per year.Likewise,average article citations were less than four per year before 1990,but were around four per article per year after 2000;(2)the major subjects using tree ring stable isotopes include forestry,geosciences,and environmental sciences,contributing to 42.5%of the total during 1974-2023;(3)the top three most productive institutions are the Chinese Academy of Sciences(423),the Swiss Federal Institute for Forest,Snow and Landscape Research(227),and the University of Arizona(204).These achievements result from strong collaborations;(4)review papers,for example,(Dawson et al.,Annu Rev Ecol Syst 33:507-559,2002)and(McCarroll and Loader,Quat Sci Rev 23:771-801,2004),are among the most cited,with more than 1000 citations;(5)tree ring stable isotope studies mainly focus on climatology and ecology,with atmospheric CO_(2) one of the most popular topics.Since 2010,precipitation and drought have received increasing attention.Based on this analysis,the research stages,key findings,debated issues,limitations and direc-tions for future research are summarized.This study serves as an important attempt to understand the progress on the use of stable isotopes in tree rings,providing scientific guid-ance for young researchers in this field.

Climate-growth relationships of Pinus tabuliformis along an altitudinal gradient on Baiyunshan Mountain,Central China

A set of standard chronologies for tree-ring width(TRW),earlywood width(EWW)and latewood width(LWW)in Pinus tabuliformis Carr.along an altitudi-nal gradient(1450,1400,and 1350 m a.s.l.)on Baiyunshan Mountain,Central China to analyze the effect of varying temperature and precipitation on growth along the gradi-ent.Correlation analyses showed that at all three altitudes and the TRW and EWW chronologies generally had signifi-cant negative correlations with mean and maximum tem-peratures in the current April and May and with minimum temperatures in the prior July and August,but significant positive correlations with precipitation in the current May.Correlations were generally significantly negative between LWW chronologies and all temperatures in the prior July and August,indicating that the prior summer temperature had a strong lag effect on the growth of P.tabuliformis that increased with altitude.The correlation with the standard-ized precipitation evapotranspiration index(SPEI)confirmed that wet conditions in the current May promoted growth of TR and EW at all altitudes.Significant altitudinal differences were also found;at 1400 m,there were significant positive correlations between EWW chronologies and SPEI in the current April and significant negative correlations between LWW chronologies and SPEI in the current September,but these correlations were not significant at 1450 m.At 1350 m,there were also significant negative correlations between the TRW and the EWW chronologies and SPEI in the prior October and the current July and between LWW chronology and SPEI in the current August,but these cor-relations were not significant at 1400 m.Moving correlation results showed a stable response of EWW in relation to the SPEI in the current May at all three altitudes and of LWW to maximum temperature in the prior July-August at 1400 m from 2002 to 2018.The EWW chronology at 1400 m and the LWW chronology at 1450 m were identified as more suitable for climate reconstruction.These results provide a strong scientific basis for forest management decisions and climate reconstructions in Central China.

Beyond authorship: Analyzing contributions in PLOS ONE and the challenges of appropriate attribution

Purpose:This study aims to evaluate the accuracy of authorship attributions in scientific publications,focusing on the fairness and precision of individual contributions within academic works.Design/methodology/approach:The study analyzes 81,823 publications from the journal PLOS ONE,covering the period from January 2018 to June 2023.It examines the authorship attributions within these publications to try and determine the prevalence of inappropriate authorship.It also investigates the demographic and professional profiles of affected authors,exploring trends and potential factors contributing to inaccuracies in authorship.Findings:Surprisingly,9.14%of articles feature at least one author with inappropriate authorship,affecting over 14,000 individuals(2.56%of the sample).Inappropriate authorship is more concentrated in Asia,Africa,and specific European countries like Italy.Established researchers with significant publication records and those affiliated with companies or nonprofits show higher instances of potential monetary authorship.Research limitations:Our findings are based on contributions as declared by the authors,which implies a degree of trust in their transparency.However,this reliance on self-reporting may introduce biases or inaccuracies into the dataset.Further research could employ additional verification methods to enhance the reliability of the findings.Practical implications:These findings have significant implications for journal publishers,Beyond authorship:Analyzing contributions in PLOS ONE and Maddi,A.,&the challenges of appropriate attribution highlighting the necessity for robust control mechanisms to ensure the integrity of authorship attributions.Moreover,researchers must exercise discernment in determining when to acknowledge a contributor and when to include them in the author list.Addressing these issues is crucial for maintaining the credibility and fairness of academic publications.Originality/value:This study contributes to an understanding of critical issues within academic authorship,shedding light on the prevalence and impact of inappropriate authorship attributions.By calling for a nuanced approach to ensure accurate credit is given where it is due,the study underscores the importance of upholding ethical standards in scholarly publishing.

Soundscape of the West Lake Scenic Area with profound cultural background—a case study of Evening Bell Ringing in Jingci Temple,China

From the case study of Evening Bell Ringing at Nanping Hill,one of the West Lake Cultural Landscapes in Hangzhou,China,we investigated the soundscape of a scenic area with a profound cultural background.First,we conducted the soundscape physical index of the area in both winter and spring seasons to analyze its objective graphical expression.Second,we focused on people's reactions to the soundscape in order to obtain a subjective evaluation of each component in the soundscape and integrated environment.Then,the relationship between the objective data and the subjective evaluation was analyzed.Finally,the impacts of the natural environment,history,and cultural factors on the evaluation of the Jingci Temple soundscape were studied.It was found that natural sounds,cultural sounds,and historic sounds were widely acclaimed in people's subjective feelings,which indicated the close relationships among historical and cultural background,soundscape,and natural environment.Thus,the conclusion was made that soundscape should be consistent with the local natural environment and the historical and cultural background.