RATE VARIATIONAL EXTREMUM PRINCIPLES FOR FINITE ELASTOPLASTICITY

Dual variational extremum principles for rate problems of classical elastoplasticitv at finite deformation are studied in Updated Lagrangian rate forms. It is proved that the convexity of the variational functionals are closely related to a so-called gap function, which plavs an important role in nonlinear variational problems.

V_r:A new index to represent the variation rate of geomagnetic activity

By calculating the hourly standard deviation of the first-order differences of the horizontal geomagnetic com- ponent minute data, a new index Vr to represent the variation rate of the geomagnetic field was introduced. Vr-indices show similar trends in the temporal change at different observatories and have simultaneous peak values at the observatories cov- ering a large span geographically, which reveals that the source of geomagnetic disturbances represented by Vr is in the mag- netosphere. Based on the comparison among Vr, Kp and ap, it is found that generally Vr changes linearly with Kp and ap, which means that the rapid changes of magnetic field usually exist together with magnetic disturbances. But there are excep- tions. As Vr can be easily produced by individual observatory in quasi real time and is more sensitive to the variation rate of geomagnetic field rather than the field itself, it can be expected to serve for monitoring or predicting the geomagnetic-induced event in a quick and intuitive way.

Annual variation rate of global sea－level rise and the prediction for the 21st century

An analytics method of predicting the annual variation rate (AVR) of global sea-level (GSL) is developed.Through the calculation by using the mean sea-level data collected from the tidal gauge stations over the world, a GSL rise of 0. 15～0. 16 cm/a is obtained. The predicted values of AVR of GSL for the 21st century are presented. The authors' results have been compared to those reported by other scientists at home and abroad. The method proposedhere is more convenient and precise.

Variation of rate of exserted stigma in P(T) GMS lines of rice

Rate of exserted stigmas (RES), ie. the ratio of glumes with exserted stigmas to the total glumes is one of the most important characteristics which affects the out-crossing rate of its combinations. Sixteen P(T) GMS lines with different ecotypes were used to study the variations of RES during their stable sterile period in Wuhan from 1992—1993. Ten healthy panicles were randomly selected at full anthesis. Their colour and the number of glumes showing one-side or two-side exserted of stigmas were investigated. Table 1 showed that there were a great variations of RES among the 16 lines tested in two consecutive years (c.v.=43.38%) and among the

Predictive performance of the variation rate of the driving pressure on the outcome of invasive mechanical ventilation in patients with acute respiratory distress syndrome

Purpose:To assess the value of the driving pressure variation rate(ΔP%)in predicting the outcome of weaning from invasive mechanical ventilation in patients with acute respiratory distress syndrome.Methods:In this case-control study,a total of 35 patients with moderate-severe acute respiratory distress syndrome were admitted to the intensive care unit between January 2022 and December 2022 and received invasive mechanical ventilation for at least 48 h were enrolled.Patients were divided into successful weaning group and failed weaning group depending on whether they could be removed from ventilator support within 14 days.Outcome measures including driving pressure,PaO2:FiO2,and positive end-expiratory pressure,etc.were assessed every 24 h from day 0 to day 14 until successful weaning was achieved.The measurement data of non-normal distribution were presented as median(Q1,Q3),and the differences between groups were compared by Wilcoxon rank sum test.And categorical data use the Chi-square test or Fisher's exact test to compare.The predictive value ofΔP%in predicting the outcome of weaning from the ventilator was analyzed using receiver operating characteristic curves.Results:Of the total 35 patients included in the study,17 were successful vs.18 failed in weaning from a ventilator after 14 days of mechanical ventilation.The cut-off values of the medianΔP%measured by Operator 1 vs.Operator 2 in the first 4 days were≥4.17%and 4.55%,respectively(p<0.001),with the area under curve of 0.804(sensitivity of 88.2%,specificity of 64.7%)and 0.770(sensitivity of 88.2%,specificity of 64.7%),respectively.There was a significant difference in mechanical ventilation duration between the successful weaning group and the failure weaning group(8(6,13)vs.12(7.5,17.3),p=0.043).The incidence of ventilator-associated pneumonia in the successful weaning group was significantly lower than in the failed weaning group(0.2‰vs.2.3‰,p=0.001).There was a significant difference noted between these 2 groups in the 28-day mortality(11.8%vs.66.7%,p=0.003).Conclusion:The medianΔP%in the first 4 days of mechanical ventilation showed good predictive performance in predicting the outcome of weaning from mechanical ventilation within 14 days.Further study is needed to confirm this finding.

Comparative Analysis of Climatic Change Trend and Change-Point Analysis for Long-Term Daily Rainfall Annual Maximum Time Series Data in Four Gauging Stations in Niger Delta

The aim of this study is to establish the prevailing conditions of changing climatic trends and change point dates in four selected meteorological stations of Uyo, Benin, Port Harcourt, and Warri in the Niger Delta region of Nigeria. Using daily or 24-hourly annual maximum series (AMS) data with the Indian Meteorological Department (IMD) and the modified Chowdury Indian Meteorological Department (MCIMD) models were adopted to downscale the time series data. Mann-Kendall (MK) trend and Sen’s Slope Estimator (SSE) test showed a statistically significant trend for Uyo and Benin, while Port Harcourt and Warri showed mild trends. The Sen’s Slope magnitude and variation rate were 21.6, 10.8, 6.00 and 4.4 mm/decade, respectively. The trend change-point analysis showed the initial rainfall change-point dates as 2002, 2005, 1988, and 2000 for Uyo, Benin, Port Harcourt, and Warri, respectively. These prove positive changing climatic conditions for rainfall in the study area. Erosion and flood control facilities analysis and design in the Niger Delta will require the application of Non-stationary IDF modelling.

Spatial-temporal Evolvement Characteristics of Climate Productivity for the Plants on Inner Mongolia Desert Steppe

Thornthwaite Memorial model and other statistic methods were used to calculate the climate-productivity of plants with the meteorological data from 1961 to 2007 at 9 stations distributed on Inner Mongolia desert steppe.The spatial and temporal variation characteristics of climate-productivity were analyzed by using the methods of the tendency rate of the climate trend,accumulative anomaly,and spatial difference and so on.The results showed that the climate-productivity kept linear increased trend over Inner Mongolia desert steppe in recent 47 years,but not significant.In spatial distribution,the climate-productivity reduced with the increased latitude.The climate-productivity in southwest part of Inner Mongolia desert steppe was growing while that in the southeast was reducing.The variation rate of the climate-productivity increased from the northwest part to the southeast part of Inner Mongolia desert steppe.In recent 47 years,the climate-productivity in southeast Jurh underwent the greatest decreasing extent,and the region was the sensitive area of the climate-productivity variation.

Diurnal and seasonal variation of the elevation gradient of air temperature in the northern flank of the western Qinling Mountain range,China

The typically sparse or lacking distribution of meteorological stations in mountainous areas inadequately resolves temperature elevation variability. This study presented the diurnal and seasonal variations of the elevation gradient of air temperature in the northern flank of the western Qinling Mountain range,which has not been thoroughly evaluated. The measurements were conducted at 9 different elevations between 1710 and 2500 m from August 2014 to August 2015 with HOBO Data loggers. The results showed that the annual temperature lapse rates(TLRs) for Tmean,Tmin and Tmax were 0.45?C/100 m,0.44?C/100 m and 0.40?C/100 m,respectively,which are substantially smaller than the often used value of 0.60°C/100 m to 0.65°C/100 m. The TLRs showed no obvious seasonal variations,except for the maximum temperature lapse rate,which was steeper in winter and shallower in spring. Additionally,the TLRs showed significant diurnal variations,with the steepest TLR in forenoon and the shallowest in early morning or late-afternoon,and the TLRs changed more severely during the daytime than night time. The accumulated temperature above 0°C,5°C and 10°C(AT0,AT5 and AT10) decreased at a lapse rate of 112.8?C days/100 m,104.5?C days/100 m and 137.0?C days/100 m,respectively. The monthly and annual mean diurnal range of temperatures(MDRT and ADRT) demonstrated unimodal curves along the elevation gradients,while the annual range of temperature(ART) showed no significant elevation differences. Our results strongly suggest that the extrapolated regional TLR may not be a good representative for an individual mountainside,in particular,where there are only sparse meteorological stations at high elevations.

ON PROBLEMS OF U-SHAPED BELLOWS WITH NONLINEAR DEFORMATION OF LARGE AXISYMMETRICAL DEFLECTION(Ⅱ)——COUNTING VARIATION OF THICKNESS DISTRIBUTION

On the basis of paper[1],assuming the logarithm of thickness at arbitrary point on a U-shaped bellows meridian is linear with the logarithm of distance between that point and axis of symmetry,perturbation solutions of the corresponding problems of large axisymmetrical deflection are given.The effects of thickness distribution variation,which result from technology factors,on stiffness of bellows are discussed.

Recent geodynamics of major strike-slip zones

The subject of this study is strike-slip fault zones, where temporal variations of accumulation in strike-slip deformation complicate the standard process of deformation accu- mulation and release during strong earthquakes. These temporal variations are expressed in the E1 Ghab segment of the Dead Sea Transform zone （DST, Eastern Mediterranean） and in the Talas-Fergana fault zone （Central Asia）. According to Global Positioning System （GPS） data, the strike-slip deformations within these zones are not now accumulating or are accumulating at a rate that is significantly less than their average rate during the Holocene and Quaternary or the Pliocene-Quaternary. Simultaneously, weak transverse shortening has been measured in both zones by GPS. In both of these zones, strong earthquakes have not registered within the XX century, yet epochs of intensified seismicity （strong earthquakes） took place throughout history. In the southern and central parts of the E1 Ghab zone, there is evidence of 30 strong historical earthquakes of Ms ≥ 5.7; however, no instrumental earthquakes of Ms 〉 5 have been identified. The temporal distribution of seismic energy released by these earthquakes demonstrates a 350 ± 50-year cycle. Values for the seismic energies released during the peak phases of these cycles are approximated by a sinusoid that suggests the possibility of a 〉1800-year cycle （＂hyper-cycle＂）, which began around the 3rd century, reached its maximum in the 12th century, and has continued until now. A combination of geological, archaeoseismological, and geodetic data show that the rate of sinistral strike-slip deformation varied in the fault zone, probably in conformity with the variation of seismicity during the ＂hyper-cycle.＂ In the Talas-Fergana fault zone, trenching and 14C dating that was correlated with right lateral offsets, gave a possible preliminary estimate of the average rates of the Late Holocene strike slip of about 10 mm per year, with a decrease in the SE direction to 4 mm-4.5 mm per year. These studies also showed that the slip in the Talas-Fergana fault zone was realized mainly during strong earthquakes. New trenching and 14C dating of paleoearthquake records identified the epoch of seismicity intensification dating to the XIV-XVII centuries. These paleoearthquakes could produce a total dextral slip at several meters. Therefore, consid- eration of these epochs was necessary to determine a calculated average slip rate during the Late Holocene.

Effect of temporal variation rate of cross polar cap potential on the equatorial ionospheric vertical drift: A statistical study

Based on the equatorial vertical ion drift measured by DMSP and cross polar cap potential （Фcpc） from AMIE output during 2001 to 2003, this paper investigates the relationship of Фcpc and its temporal variation rate （△Фcpc） with the disturbed ion velocity （△Vx） which is the difference between the disturbed days （Kp〉4） and quiet days （Kp〈2）. The statistical analysis shows： （1） The △Vx correlates better with AФcpc than with Фcpc, indicating that the electric field penetration is more easily to occur when solar wind input rapidly varies with time. （2） The optimal delay time of electric field penetration from the high-latitude magnetosphere to equatorial ionosphere has local time dependence which is longer on the nightside than on the dayside. It may be due to more complicated electrodynamic process on the nightside. （3） With the linear relationship between △Фcpc and △Vx, it is obtained that the penetration efficiency is about 4.5%-13.9% at day and 31%-42% at night, coinciding well with former studies.

A Method of Polydirectional Fuzzy Synthetical Cluster of Considering Partiality of Decision Maker

Based on analyzing traditional fuzzy cluster method, this paper presents a new method for building fuzzy similar matrix R and a method of polydirectional synthetical fuzzy cluster, which can fully reflect the partiality and experience of policymakers. This method is simple, practical and can reflect thing’s feature comprehensively, so it has certain practical value.

Reconstructing evolutionary timescales using phylogenomics

Reconstructing the timescale of the Tree of Life is one of the principal aims of evolutionary biology. This has been greatly aided by the development of the molecular clock, which enables evolutionary timescales to be estimated from genetic data. In recent years, high-throughput sequencing technology has led to an increase in the feasibility and availability ofgenome-scale data sets. These represent a rich source of biological information, but they also bring a set of analytical challenges. In this review, we provide an overview of phylogenomic dating and describe the challenges associated with analysing genome-scale data. We also report on recent phylogenomic estimates of the evolutionary timescales of mammals, birds, and insects.