On the long-term joint distribution of characteristic wave height and period and its application

By analysing the scatter diagrams of characteristic the wave height H and the period T on the basis of instrumental data from various ocean wave stations, we found that the conditional expectation and standard deviation of wave period for a given wave height can be better predicted by using the equations of normal linear regression rather than by those based on the log- normal law. The latter was implied in Ochi' s bivariate log-normal model(Ochi. 1978) for the long-term joint distribution of H and T. With the expectation and standard deviation predicted by the normal linear regression equations and applying proper types of distribution, we have obtained the conditional distribution of T for given H. Then combining this conditional P(T / H) with long-term marginal distribution of the wave height P(H) we establish a new parameterized model for the long-term joint distribution P(H,T). As an example of the application of the new model we give a method for estimating wave period associated with an extreme wave height.

Labile Organic Matter Content and Distribution as Affected by Six-year Soil Amendments to Eroded Chinese Mollisols

Labile organic carbon （LOC） is a fraction of soil organic carbon （SOC） with rapid turnover time and is affected by soil fertilization. This investigation characterized the SOC content, LOC content and LOC distribution in the treatment plots of surface soil erosion at five levels （0-, 5-, 10-, 20- and 30-cm erosion）. The soil had received contrasting fertilizer treatments （i.e., chemical fertilizer or chemical fertilizer ＋ manure） for 6 years. This study demonstrated that both SOC and various LOC fractions contents were higher in the plots with fertilizer ＋ manure than in those with fertilizer alone under the same erosion conditions. The SOC and LOC contents de- creased as the erosion depth increased. Light fraction organic carbon, particulate organic carbon, easily oxidizable organic carbon （KMnO4-oxydizable organic carbon）, and microbial biomass carbon were 27% 57%, 37%-7%, 20%-25%, and 29%-33% higher respectively in the fertilizer ＋ manure plots, than in the fertilizer alone plots. Positive correlations （p 〈 0.05） between SOC content and different fractions contents were observed in all plots except the correlation between total SOC content and water-soluble organic carbon content in the different fertilization treatments. Obviously, fertilizer ＋ manure treatments would be conducive to the accumulation of LOC and SOC in the Black soil of Northeast China.

Analysis of Wave Distributions Using the WAVEWATCH-III Model in the Arctic Ocean

In this work,we examined long-term wave distributions using a third-generation numerical wave model called WAVE-WATCH-III(WW3)(version 6.07).We also evaluated the influence of sea ice on wave simulation by using eight parametric switches.To select a suitable ice-wave parameterization,we validated the simulations from the WW3 model in March,May,September,and December 2017 against the measurements from the Jason-2 altimeter at latitudes of up to 60°N.Generally,all parameterizations ex-hibited slight differences,i.e.,about 0.6 m root mean square error(RMSE)of significant wave height(SWH)in May and September and about 0.9 m RMSE for the freezing months of March and December.The comparison of the results with the SWH from the European Centre for Medium-Range Weather Forecasts for December 2017 indicated that switch IC4_M1 performed most effec-tively(0.68 m RMSE)at high latitudes(60°-80°N).Given this finding,we analyzed the long-term wave distributions in 1999-2018 on the basis of switch IC4_M1.Although the seasonal variability of the simulated SWH was of two types,i.e.,‘U’and‘sin’modes,our results proved that fetch expansion prompted the wave growth.Moreover,the interannual variability of the specific regions in the‘U’mode was found to be correlated with the decade variability of wind in the Arctic Ocean.

Video caching and scheduling with edge cooperation

In this paper,we explore a distributed collaborative caching and computing model to support the distribution of adaptive bit rate video streaming.The aim is to reduce the average initial buffer delay and improve the quality of user experience.Considering the difference between global and local video popularities and the time-varying characteristics of video popularity,a two-stage caching scheme is proposed to push popular videos closer to users and minimize the average initial buffer delay.Based on both long-term content popularity and short-term content popularity,the proposed caching solution is decouple into the proactive cache stage and the cache update stage.In the proactive cache stage,we develop a proactive cache placement algorithm that can be executed in an off-peak period.In the cache update stage,we propose a reactive cache update algorithm to update the existing cache policy to minimize the buffer delay.Simulation results verify that the proposed caching algorithms can reduce the initial buffer delay efficiently.

Soil pH Dynamics and Nitrogen Transformations Under Long-Term Chemical Fertilization in Four Typical Chinese Croplands

Long-term fertilization experiment provides the platform for understanding the proton budgets in nitrogen transformations of agricultural ecosystems. We analyzed the historical （1990-2005） observations on four agricultural long-term experiments in China （Changping, Chongqing, Gongzhuling and Qiyang） under four different fertilizations, i.e., no-fertilizer （control）, sole chemical nitrogen fertilizer （FN）, sole chemical phosphorous and potassium fertilizers （FPK） and chemical nitrogen, phosphorous and potassium fertilizers （FNPK）. The significant decline in topsoil pH was caused not only by chemical N fertilization （0.29 and 0.89？pH at Gongzhuling and Qiyang, respectively） but also by chemical PK fertilization （0.59？pH at Gongzhuling）. The enhancement of available nutrients in the topsoil due to long-term direct nutrients supply with chemical fertilizers was in the descending order of available P （168-599%）〉available K （16-189%）〉available N （9-33%）. The relative rate of soil pH decline was lower under long-term judicious chemical fertilization （-0.036-0.034 ？pH yr-1） than that under long-term sole N or PK fertilization （0.016-0.086 ？pH yr-1）. Long-term judicious chemical fertilization with N, P and K elements decreases the nutritional limitation to normal crop growth, under which more N output was distributed in biomass removal rather than the loss via nitrate leaching. We concluded that the N distribution percentage of nitrate leaching to biomass removal might be a suitable indicator to the sensitivity of agricultural ecosystems to acid inputs.

Long-term Correlations and Extreme Wind Speed Estimations

In this paper, we use fluctuation analysis to study statistical correlations in wind speed time series. Each time series used here was recorded hourly over 40 years. The fluctuation functions of wind speed time series were found to scale with a universal exponent approximating to 0.7, which means that the wind speed time series are long-term correlated. In the classical method of extreme estimations, data are commonly assumed to be independent (without correlations). This assumption will lead to an overestimation if data are long-term correlated. We thus propose a simple method to improve extreme wind speed estimations based on correlation analysis. In our method, extreme wind speeds are obtained by simply scaling the mean return period in the classical method. The scaling ratio is an analytic function of the scaling exponent in the fluctuation analysis.

Temperature field test and prediction using a GA-BP neural network for CRTS Ⅱ slab tracks

The CRTS Ⅱ slab track, which is connected in a longitudinal direction, is one of the main ballastless tracks in China, with approximately 7365 km of operational track. Temperature loading is a very vital factor leading to slab track damages such as warping and cracking. While existing research on temperature distribution rests on either site tests in special environments or theoretical analysis, the long-term temperature field characteristics are not clear. Therefore, a long-term temperature field test for the CRTS Ⅱ slab track on bridge-subgrade transition section was conducted to analyze the temperature field. A GA-BP(genetic algorithm optimized back propagation) neural network was trained on the test data to predict the temperature field. The vertical and lateral temperature distributions in four typical days were carried out. We found that the temperature along the track was distributed in a nonlinear manner. This was particularly distinct in the vertical direction for depths of less than 300 mm. The highest and lowest daily temperatures and the daily range of the temperature were analyzed. With the increasing depth, the daily highest temperatures and range of the temperature were smaller, the daily lowest temperatures were higher, and the time corresponding to this peak value appeared later in the day. Both the highest and lowest daily temperature could be predicted using the GA-BP neural network, though the accuracy in predicting the highest temperature was higher than that in predicting the lowest temperature.

June to October Aerosol Optical Depth over the Arctic at Various Spatial and Temporal Scales in MODIS, MAIAC, CALIOP and GOES Data

The accuracy of the cloud-aerosol lidar with orthogonal polarization (CALIOP), moderate resolution imaging spectroradiometer (MODIS), Multi-Angle Implementation of Atmospheric Correction (MAIAC), and Geostationary Operational Environmental Satellite (GOES) aerosol optical depth (AOD) products for the Arctic north of 59.75°N was examined by means of 35 aerosol robotic network (AERONET) AOD sites. The assessment for June to October 2006 to 2020 showed MAIAC AOD agreed the best with AERONET AOD;CALIOP AOD differed the strongest from the AERONET AOD. Cross-correlations of CALIOP AOD along the satellite path indicated that AOD-values 40 km up-and-down the path often failed to represent the AERONET AOD-values within ±30 min of the overpass in this region dominated by easterly winds. Typically, CALIOP AOD was lower than AERONET AOD and MAIAC AOD at the sites, especially, at sites with mean AOD below 0.1. Generally, MODIS AOD values exceeded those of MAIAC. Comparison of CALIOP, MAIAC, and MODIS products resampled on a 0.25° × 0.25° grid revealed differences among the products caused by their temporal and spatial resolution, sample habit and size. Typically, the MODIS AOD-product showed the most details in AOD distribution. Despite differences in AOD-values, all products provided similar temporal evolution of elevated and lower AOD.

声纹鉴定中的音强特征研究

目的确定声纹鉴定中的音强特征的应用价值。方法将10名条件相近、普通话较标准的男性发音人的语音样本输入VS-99型语音工作站,分别对每个人所发的相同音节韵母的宽带声纹图谱进行分析比对。结果不同人发出的相同音节,其音强分布一般不同,有时还会出现明显的差异,主要表现在韵母总体音强按频率分布状态、韵母总体音强按时间分布状态、过渡段音强按频率的分布状态、共振峰间的相对音强、个体共振峰的音强分布、共振峰峰间音强等几个方面;而同一人发出的相同音节,在上述几方面则表现一致。结论音强可作为声纹鉴定中的一类特征。

长时共振峰分布特征在声纹鉴定中的应用

目的利用长时共振峰分布特征区分不同发音人。方法以汉语普通话为语料,对20位男性发音人和20位女性发音人的前四条共振峰的长时分布情况进行了统计比较分析。结果发现各长时共振峰分布的均值、中位数、众数、峰数、峰度和斜度等参数能够反映出不同发音人的个性特征,稳定性较强。前四条长时共振峰的分布结构比较均匀,由此推测在语料足够长的情况下,所有元音平均后的结果应该是一个类似央元音的"音"。结论利用长时共振峰分布特征可以较好地区分不同发音人。

基于能量分布和共振峰结构的汉语鼻音检测

该文提出了一种基于能量分布和共振峰结构的汉语鼻音检测方法,该方法首先基于Seneff听觉谱提取了一组描述音段能量分布和共振峰结构的特征参数,然后采用支持向量机模型进行检测和分类,得到候选的鼻音,最后根据音段持续时间、前端韵母能量、高低频能量差、中低频能量比等特征对候选的鼻音进行后处理,去除插入错误,提高鼻音检测的准确率。实验结果表明,干净语音鼻音检测准确率可以达到90.4%,信噪比10dB的语音鼻音检测准确率可达到84.4%以上。

Discussion on the parameters of design waves

In order to respond the discredit on the design wave standard and to recommend new consideration on design wave parameters, based on the long-term distribution of statistic characteristics of waves and the short-term probability properties of sea state defined by giving the return period, the calculation of the return period, the height, the period, and the oceanic wave parameters of the design wave and the forecasting methods are discussed in this paper. To provide references for the operation reliability of floating structures in the extreme sea state, the method of determining the design wave parameters is resurveyed. A proposal is recommended that the design wave, which can be either significant wave with 500-year of the return period, or the maximum wave with 1/N of exceeding probability, 100-year of the return period, can be applied in the engineering design practice.

Fatigue reliability for LNG carrier

The procedure of reliability-based fatigue analysis of liquefied natural gas(LNG) carrier of membrane type under wave loads is presented. The stress responses of the hotspots in regular waves with different wave heading angles and wave lengths are evaluated by global ship finite element method(FEM) . Based on the probabilistic distribution function of hotspots' short-term stress-range using spectral-based analysis,Weibull distribution is adopted and discussed for fitting the long-term probabilistic distribution of stress-range. Based on linear cumulative damage theory,fatigue damage is characterized by an S-N relationship,and limit state function is established. Structural fatigue damage behavior of several typical hotspots of LNG middle ship section is clarified and reliability analysis is performed. It is believed that the presented results and conclusions can be of use in calibration for practical design and initial fatigue safety evaluation for membrane type LNG carrier.

音量增大时语音的长时共振峰分布特征变化及其对声纹鉴定的影响

长时共振峰分布特征是近年来才开始使用的研究方法。目前尚未广泛的应用于声纹鉴定实务。本文将采用长时共振峰分布特征来探究声纹鉴定实务中经常遭遇的一种情形,即检材语音和样本语音音量不同的情况。实验用Lombard效应法增大语音,对30位发音人在正常和85分贝噪音两种不同的条件下进行录音。考察长时共振峰分布特征的变化,以期对声纹鉴定实务提供帮助。

Effect of grain boundary precipitates on the stress rupture properties of K4750 alloy after long-term aging at 750℃for 8000 h

In K4750 alloy,the evolution of grain boundary(GB)precipitates,including the degradation of blocky MC carbide particles and the precipitation of granular/needle-likeηphase particles,were observed after longterm aging(LA)at 750℃for 8000 h.During MC degradation,the Ti and C released from the MC carbide combined with Ni and Cr,respectively,in theγ’matrix to formη-Ni_(3)Ti phase and Cr-rich M_(23)C_(6)carbide.Large amounts of granularηphase precipitated at GBs and the needle-likeηphase grew gradually from GBs toward the grain interior.Because of the growth of theηphase through absorbingγ’phase,γ-depleted zones were formed around theηphase.The evolution of the MC carbide andηphase was primarily responsible for the decrease of the stress rupture life and the increase of elongation.After an LA sample was tested at 750℃and 360 MPa,the residual strain distribution was investigated by electron backscatter diffraction(EBSD).The results showed that the residual strain mainly distributed at GBs,especially in the region of MC degradation and at the edges ofηphases,which was closely related to the appearance of phase interfaces.Microvoids/cracks easily initiated at phase interfaces,then easily extended along theγ-depleted zones,thus the stress rupture life of LA samples was substantially shorter than that of samples subjected to the standard treatment.In particular,because of large amounts of fine degraded MC,granular M_(23)C_(6)and granularηphase particles distributed at GBs after 750℃/8000 h LA and microvoid/crack formation could be hindered by the formation of dimples,which led to an increase of elongation.

Variability and trends in land surface longwave radiation fluxes from six satellite and reanalysis products

Earth surface longwave radiation(SLR),including downward(DLR),upward(ULR),and net longwave radiation(NLR),significantly impacts the surface radiation budget and global climate evolution.However,the spatiotemporal variation in SLR remains poorly understood.In this study,three satellite products(GLASS-MODIS V40,GLASS-AVHRR,and CERES-SYN)and three reanalysis datasets(ERA5,MERRA-2,and GLDAS)were validated using ground measurements from 288 sites at seven observation networks.The mean biases and root mean square errors of the monthly DLR(ULR,NLR)estimates from the six products were-6.36(-3.56,-2.86)Wm^(-2) and 16.63(14.33,13.38)Wm^(-2),respectively.Large differences in the spatial distribution of the SLR were mainly observed at high-latitude,high-altitude and desert/barren-covered regions.Large interannual variability was detected at high latitudes.GLASS-AVHRR and ERA5 better captured the long-term variability in DLR and ULR,whereas GLASS-AVHRR and MERRA-2 better detected trends in NLR.An increasing trend in DLR and ULR was observed between 1982 and 2015,followed by a decreasing trend from 2016 to 2021;the NLR flux did not exhibit a significant trend.Overall,the GLASS-AVHRR and ERA5 SLR estimates were more accurate and stable than those of the,other products in accuracy,spatiotemporal distribution,and trend analysis.

Community-based population monitoring for large baleen whales:the case study of Bryde’s whale in Beibu Gulf of China

Citizen science is a popular method for the long-term monitoring of the distribution of wild animals.The application of these methods in different species and environments still poses challenges,especially for aquatic animals.In this study,we investigated the distribution of the Bryde’s whale(Balaenoptera edeni)in the Beibu Gulf of China by using scientific boat-based surveys and citizen science approaches using 2 different methods of data collection.First,we built our mobile app(Whale Guard)and installed it on fishermen’s phones.Second,we used a popular instant messaging app(WeChat)to create an online fisherman community.We found that the mobile phone app collected far fewer reports(5 reports)than the online community group(42 reports,P<0.01).By using a variety of incentives,we maintained the fisherman’s community’s activity without significant user loss(P<0.01).We also found that the locations collected by social media applications in this study were consistent with observations from scientific boat-based transect surveys.The sightings distribution of Bryde’s whales differed from those in previous surveys in that they were present across larger areas.Social media apps reported that 69%of reports was confirmed by more than one person,whereas Whale Guard reports were much lower(0,P<0.001).Community-based citizen science can greatly contribute to the long-term monitoring of Bryde’s whales,and it has successfully overcome the challenges of data accessibility,accuracy,and fragmentation.Our study shows how to appropriately use citizen science in different community groups and community-based approaches make them useful for large baleen whale surveys.

中国人学習者による日本語母音の発音再考

元音是发音的基础,对它的教学方法看似成熟,但是日语学习者对'ウ'和'エ'的发音错误仍然是目前教学中的常见问题,有必要对此进行重新探讨。经过对中国人和日本人发音者的共振峰频率进行对比分析,我们发现两组发音者差异最明显的元音是'ウ',同时'エ'和'オ'也存在差异。这些元音的共同点在于汉语母语中没有固定的元音区域,因此学习者不能很好地控制元音发音,也无法应对由于前后增加其他音素引起的发音环境的变化。从元音区域来看,日语的'ウ'与汉语的/e/同为后高元音。汉语/e/的F2处于日语母语者与学习者发'ウ'音时的中间位置。我的假设是,由于汉语/e/存在固定的元音区域,因此学习者在发日语的/u/音时舌位不前移。

Wheat yield prediction by zero sink and equilibrium-type soil phosphorus tests

Diffusive gradients in thin films(DGT)measurements have been shown to outperform other phosphorus(P)tests in soils with strong P sorption,but this has not been confirmed for moderately weathered European soils.We compared the performance of DGT in predicting wheat grain yield in Swedish long-term fertility experiments with those of standard intensity(water-extractable P(P-H2O))and quantity(ammonium lactate-extractable P(P-AL))tests.A Mitscherlich-type model was used to fit wheat yield response to P application rates(0,15,30 or 35,and 45 kg P ha-1 year-1)in each individual trial replicate to estimate the maximum yield.For trials with clear plateau-type yield responses and the goodness of fit(R2)>0.75,relative yields(RYs)were calculated for each P treatment and plotted against the soil P test results(n=143).The goodness of the Mitscherlich-type fits decreased in the following order:DGT-measured P(P-DGT)(R2=0.35)>P-H2O(R2=0.18)>P-AL(R2=0.13).When excluding soils with P-AL:P-DGT≥0.1 L g-1,R2 was considerably improved to 0.55 for P-AL,0.46 for P-H2O,and 0.65 for P-DGT(n=61).At 95%of maximum yield,the upper limit of P deficiency for P-DGT was 44.8(the soils with P-AL:P-DGT<0.1 L g-1)and 61.9μg L-1(all soils),falling within the range reported for other European and Australian soils(6.0–142μg L-1).We show that in the investigated Swedish soils,DGT performed better than the quantity and intensity tests,which is attributed to its ability to capture P diffusion and resupply from the soil solid phase,similar to plant roots in the rhizosphere.