Epidemic Characteristics and Spatio-Temporal Patterns of HFRS in Qingdao City,China,2010-2022

Objective This study investigated the epidemic characteristics and spatio-temporal dynamics of hemorrhagic fever with renal syndrome(HFRS)in Qingdao City,China.Methods Information was collected on HFRS cases in Qingdao City from 2010 to 2022.Descriptive epidemiologic,seasonal decomposition,spatial autocorrelation,and spatio-temporal cluster analyses were performed.Results A total of 2,220 patients with HFRS were reported over the study period,with an average annual incidence of 1.89/100,000 and a case fatality rate of 2.52%.The male:female ratio was 2.8:1.75.3%of patients were aged between 16 and 60 years old,75.3%of patients were farmers,and 11.6%had both“three red”and“three pain”symptoms.The HFRS epidemic showed two-peak seasonality:the primary fall-winter peak and the minor spring peak.The HFRS epidemic presented highly spatially heterogeneous,street/township-level hot spots that were mostly distributed in Huangdao,Pingdu,and Jiaozhou.The spatio-temporal cluster analysis revealed three cluster areas in Qingdao City that were located in the south of Huangdao District during the fall-winter peak.Conclusion The distribution of HFRS in Qingdao exhibited periodic,seasonal,and regional characteristics,with high spatial clustering heterogeneity.The typical symptoms of“three red”and“three pain”in patients with HFRS were not obvious.

Effect of FeSi additive in dual-chamber sample cup on thermal analysis characteristic values and vermiculating rate of compacted graphite iron

Thermal analysis plays a key role in the online inspection of molten iron quality.Different solidification process of molten iron can be reflected by thermal analysis curves,and silicon is one of important elements affecting the solidification of molten iron.In this study,FeSi75 was added in one chamber of the dual-chamber sample cup,and the influences of FeSi75 additive on the characteristic values of thermal analysis curves and vermiculating rate were investigated.The results show that with the increase of FeSi75,the start temperature of austenite formation TALfirstly decreases and then increases,but the start temperature of eutectic growth TSEF,the lowest eutectic temperature TEU,temperature at maximum eutectic reaction rate TEM,and highest eutectic temperature TERkeep always an increase.The temperature at final solidification point TEShas little change.The FeSi75 additive has different influences on the vermiculating rate of molten iron with different vermiculation,and the vermiculating rate increases for lower vermiculation molten iron while decreases for higher one.According to the thermal analysis curves obtained by a dual-chamber sample cup with 0.30wt.%FeSi75 additive in one chamber,the vermiculating rate of molten iron can be evaluated by comparing the characteristic values of these curves.The time differenceΔtERcorresponding to the highest eutectic temperature TERhas a closer relationship with the vermiculating rate,and a parabolic regression curve between the time differenceΔtERand vermiculating rateηhas been obtained within the range of 65%to 95%,which is suitable for the qualified melt.

Numerical Analysis of Explosion Characteristics of Vent Gas From 18650 LiFePO_(4) Batteries With Different States of Charge

The combustion and explosion characteristics of lithium-ion battery vent gas is a key factor in determining the fire hazard of lithium-ion batteries.Investigating the combustion and explosion hazards of lithium-ion batteries vent gas can provide guidance for rescue and protection in explosion accidents in energy storage stations and new energy vehicles,thereby promoting the application and development of lithium-ion batteries.Based on this understanding and combined with previous research on gas production from lithium-ion batteries,this article conducted a study on the combustion and explosion risks of vent gas from thermal runaway of 18650 LFP batteries with different states of charge(SOCs).The explosion limit of mixed gases affected by carbon dioxide inert gas is calculated through the“elimination”method,and the Chemkin-Pro software is used to numerically simulate the laminar flame speed and adiabatic flame temperature of the battery vent gas.And the concentration of free radicals and sensitivity coefficients of major elementary reactions in the system are analyzed to comprehensively evaluate the combustion explosion hazard of battery vent gas.The study found that the 100%SOC battery has the lowest explosion limit of the vent gas.The inhibitory elementary reaction sensitivity coefficient in the reaction system is lower and the concentration of free radicals is higher.Therefore,it has the maximum laminar flame speed and adiabatic flame temperature.The combustion and explosion hazard of battery vent gas increases with the increase of SOC,and the risk of explosion is the greatest and most harmful when SOC reaches 100%.However,the related hazards decrease to varying degrees with overcharging of the battery.This article provides a feasible method for analyzing the combustion mechanism of vent gas from lithium-ion batteries,revealing the impact of SOC on the hazardousness of battery vent gas.It provides references for the safety of storage and transportation of lithium-ion batteries,safety protection of energy storage stations,and the selection of related fire extinguishing agents.

Analysis and Research on Aerodynamic Characteristics of Quad Tilt Rotor Aircraft

For the quad tilt rotor aircraft, a computational fluid dynamics method based on multiple reference frames (MRF) was used to analyze the influence of aerodynamic layout parameters on the aerodynamic characteristics of the quad tilt rotor aircraft. Firstly, a numerical simulation method for the interference flow field of the quad tilt rotor aircraft is established. Based on this method, the aerodynamic characteristics of isolated rotors, rotor combinations at different lateral positions on the wing, and rotor rotation directions under different inflow velocities were calculated and analyzed, in order to grasp their aerodynamic interference laws and provide reference for the design and control theory research of such aircraft.

Dynamical Modeling and Dynamic Characteristics Analysisof a Coaxial Dual-Rotor System

The dual-rotor structure serves as the primary source of vibration in aero-engines. Understanding itsdynamical model and analyzing dynamic characteristics, such as critical speed and unbalanced response, arecrucial for rotor system dynamics. Previous work introduced a coaxial dual-rotor-support scheme for aeroengines,and a physical model featuring a high-speed flexible inner rotor with a substantial length-to-diameter ratiowas designed. Then a finite element (FE) dynamic model based on the Timoshenko beam elements and rigid bodykinematics of the dual-rotor system is modeled, with the Newmark method and Newton–Raphson method used forthe numerical calculation to study the dynamic characteristics of the system. Three different simulation models,including beam-based FE (1D) model, solid-based FE (3D) model, and transfer matrix model, were designed tostudy the characteristics of mode and the critical speed characteristic of the dual-rotor system. The unbalancedresponse of the dual-rotor system was analyzed to study the influence of mass unbalance on the rotor system. Theeffect of different disk unbalance phases and different speed ratios on the dynamic characteristics of the dual-rotorsystem was investigated in detail. The experimental result shows that the beam-based FE model is effective andsuitable for studying the dual-rotor system.

A Study of the English Translation of Characteristic Cuisines of the Hexi Corridor from the Perspective of Multimodal Discourse Analysis

Given the diversity of geographical and cultural backgrounds,it is difficult to find precise counterparts of many food-related vocabularies in the unique dietary culture of the Hexi Corridor in the target language,making it challenging to fully convey the essence of its local dietary culture in translation.To achieve the purpose of translation,the theory of multimodal discourse analysis provides an ideal translation approach through the language mode,image mode,sound mode,and the synergistic effect of multimodalities,which can accurately address the deficiencies in the translation of dietary culture.Through this research,it is not only possible to highlight the unique charm of the dietary culture of the Hexi Corridor but also to build a bridge for its international dissemination,promoting cross-border cultural exchanges and mutual understanding.

Analysis on the Variation Characteristics of Precipitation in North China during Recent 30 Years

Based on the monthly precipitation data from 43 stations in North China from 1979 to 2008,the variation characteristics of precipitation in North China in recent 30 years were analyzed by means of empirical orthogonal function(EOF)decomposition,Morlet wavelet transform and Mann-Kendall test.The results showed that the spatial distribution of annual and seasonal precipitation was basically identical in North China,while the annual and summer precipitation from the middle of 1980s to the middle of 1990s were obviously more than these in other periods,and there was great annual variation in spring precipitation in 1990s,while autumn precipitation was higher from 1980s to 1990s and then went down after the beginning of 21st century,which was opposite to winter precipitation,namely there was more winter precipitation from 1980s to 1990s and fewer winter precipitation after the beginning of 21st century.In addition,the annual and summer precipitation changed abruptly in 1997,and there was no obvious change in spring precipitation and autumn precipitation,while winter precipitation had an abrupt change in 2000.Meanwhile,wavelet analysis revealed that the variation period of annual and seasonal precipitation was 3-4 years.

Characteristic Analysis of the Temperature Variation in Baoji City in Past 52 Years

The characteristics of the temperature variation in Baoji City were analyzed with the temperature data from 1952 to 2003.The results showed that the value of annual average temperature and seasonal average temperature wavily rose before 1980 and obviously ascended after 1980.During the period of last 52 years,there was a process of ascent-descent-ascent in summer seasonal temperature variation.While in autumn and winter,the temperature decreased at first and then increased.The steady ascent of the temperature in summer season had a great contribution to the increment of its average temperature.The type of the variation trend in the average temperature in Baoji in recent 52 years was verified according to the results.

Analysis of the Characteristics of Typical Haze in Winter

Based on meteorology and environment monitoring data in January,2008 in Liaoning central region,a typical haze weather process was analyzed.The results showed that haze was formed due to the stable weather condition in the earth surface and upper air layer in Liaoning central region.Especially because that the weakening of atmospheric dispersion ability in the urban boundary layer that was 500 m under earth surface,caused the pollutant in the air can not disperse.Thus,it resulted in the deterioration of air quality,increase of concentration of particulate mass,and declination of visibility.And in the end,haze formed.

The analysis of frequency-dependent characteristics for fluid detection: a physical model experiment

According to the Chapman multi-scale rock physical model, the seismic response characteristics vary for different fluid-saturated reservoirs. For class I AVO reservoirs and gas-saturation, the seismic response is a high-frequency bright spot as the amplitude energy shifts. However, it is a low-frequency shadow for the Class III AVO reservoirs saturated with hydrocarbons. In this paper, we verified the high-frequency bright spot results of Chapman for the Class I AVO response using the frequency-dependent analysis of a physical model dataset. The physical model is designed as inter-bedded thin sand and shale based on real field geology parameters. We observed two datasets using fixed offset and 2D geometry with different fluid- saturated conditions. Spectral and time-frequency analyses methods are applied to the seismic datasets to describe the response characteristics for gas-, water-, and oil-saturation. The results of physical model dataset processing and analysis indicate that reflection wave tuning and fluid-related dispersion are the main seismic response characteristic mechanisms. Additionally, the gas saturation model can be distinguished from water and oil saturation for Class I AVO utilizing the frequency-dependent abnormal characteristic. The frequency-dependent characteristic analysis of the physical model dataset verified the different spectral response characteristics corresponding to the different fluid-saturated models. Therefore, by careful analysis of real field seismic data, we can obtain the abnormal spectral characteristics induced by the fluid variation and implement fluid detection using seismic data directly.

Morphological Characteristics Analysis of 11 Broom Sorghum Varieties

[Objective] To provide a theoretical basis for high-yield breeding of broom sorghum.[Method] Using 11 kinds of broom sorghum collected at home as research objects, the differences in morphological characteristics of broom sorghum were compared through the survey of some indicators, such as plant height, tillering, inflorescence, stem node, stem-leaf ratio, yield, and so on. [Result] The 11 kinds of broom sorghum were different in morphological characteristics with large amplitude of plant height; zygl-1, zygl-6, zygl-8 and zygl-9 were appropriate for fixed broom type; zygl-9 had the highest integrated production. [Condusion] The study laid the foundation for further exploring breeding, cultivation and promotion of broom sorghum.

Cluster Analysis of Morphologic Characteristic of Eight Geographical Populations of Rana Dybowskii

[ObJective] The research aimed to determine the geographic distribution map of system of Rana dybowskii. [Method] Four morphologic indices （body length, body weight, forelimb length, hindlimb length） of eight geographical populations of R.dybowskii which naturally distribute in Changhai Mountain and Xiaoxing＇an Mountain were measured. Measure results were variance analyzed and cluster analyzed. [Result] Variance analysis showed： the genetic branching among the Dongfanghong male population（ belongs to Wandashan） and Xiaoxing＇an Mountain male population and Changbai Mountain male population were significantly different （P〈0.05） ; the genetic branching between the Hebei female population （belongs to Xiaoxing＇an Mountain） and Changbai Mountain female population was significantly different （P〈0.05 ）. Cluster analysis showed ： male R.dybowskii can be divided into three groups ： the first group included Quanyang, Tianbei, Chaoyang and Ddkouqin, the second group included Tieli and Anshan, the third group included Dongfanghong; and the female R. dybowskii can be divided into three groups ： the first group included Quanyang and Chaoyang, the second group included Tianbei and Dakouqin, the third group included Hebei. [Condusion] The paper deduced that the Sanjiang Plain was the geographical origin center ofR. dybowskii which radiated to Changbai Mountain and Xiaoxing＇an Mountain along the adverse current of Songhua River basin, therefore, the current distribution pattern of R. dybowskii was formed.

The runoff characteristics and harmonic analysis of the soil moisture dynamics in Robinia pseudoacacia stand

Robinia pseudoacacia stands act as a typical ecological protection forest in hilly semi-arid area of China. Two fields of surface runoff were separately set up in R. pseudoacacia stand and its clearcut area in the western Liaoning Province (1850-12225 E, 4024-4234 N) for measuring the characteristics of runoff and sediment as well as soil moisture dynamics. Contractive analysis of the two land types showed that there existed a significant difference in volumes of runoff and sediment between the sites of R. pseudoacacia stand and its clearcut area. The runoff volume and sediment volume in clearcut area were much bigger than those in R. pseudoacacia stand, with an increase amount of 40%-177% for runoff and 180%-400% for sediment. Hydrograph of surface runoff of typical rainfall showed that the peak value of runoff in R. pseudoacacia stand was decreased by 1.0-2.5?0-3m3s-1 compared with that in its clearcut area, and the occurring time of peak value of runoff in R. pseudoacacia stand was 10-20 min later than that in its clearcut area. Harmonic analysis of soil moisture dynamics indicated that the soil moisture in R. pseudoacacia stand was 2.3 % higher than that in clearcut area, and the soil moisture both in R. pseudoacacia stand and its clearcut area could be divided into dry season and humid season and varied periodically with annual rainfall precipitation. It was concluded that R. pseudoacacia stand plays a very important role in storing water, increasing soil moisture, and reducing surface runoff and soil erosion.

Circuit-Level Analysis on Opto-Electronic Characteristics of Ferroelectric Liquid Crystal

We propose an electronic model in Spice, instead of traditional mathematical analysis, for analyzing the performance of ferroelectric liquid crystal （FLC） under various working conditions. Using this equivalent circuit model,it is easy to simulate and analyze the behavior of an FLC layer in three different typical parameters,including temperature, input light wavelength, and the frequency of driving voltage. We conclude that the response velocity drops as the wavelength increases in the range of visible light, and for the parameter of temperature, the velocity reaches its lowest value when the temperature reaches a certain degree,meanwhile,the frequency of driving voltage exerts important effects on the response velocity only when the frequency is beyond a critical value. Excellent agreement is achieved between simulation and experimental results.

Pre-stack-texture-based reservoir characteristics and seismic facies analysis

Seismic texture attributes are closely related to seismic facies and reservoir characteristics and are thus widely used in seismic data interpretation.However,information is mislaid in the stacking process when traditional texture attributes are extracted from poststack data,which is detrimental to complex reservoir description.In this study,pre-stack texture attributes are introduced,these attributes can not only capable of precisely depicting the lateral continuity of waveforms between different reflection points but also reflect amplitude versus offset,anisotropy,and heterogeneity in the medium.Due to its strong ability to represent stratigraphies,a pre-stack-data-based seismic facies analysis method is proposed using the selforganizing map algorithm.This method is tested on wide azimuth seismic data from China,and the advantages of pre-stack texture attributes in the description of stratum lateral changes are verified,in addition to the method＇s ability to reveal anisotropy and heterogeneity characteristics.The pre-stack texture classification results effectively distinguish different seismic reflection patterns,thereby providing reliable evidence for use in seismic facies analysis.

Study on the Temporal and Spatial Distribution Characteristic of Acid Rain in Guangxi Based on EOF Analysis

Based on acid rain data from ten monitoring sites in Guangxi from 2003 to 2009,the temporal and spatial distribution characteristic of acid rain in Guangxi were analyzed by means of empirical orthogonal function resolution(EOF).The results showed that there was fluctuating change of acid rain frequency in Guangxi,and acid rain pollution became severer in 2004-2008;acid rain frequency changed conformably in the whole region and it was obviously higher in eastern and northwestern Guangxi,while acid rain pollution became severe in western Guangxi;acid rain frequency varied out of phase between northeastern and southwestern Guangxi in an individual year.

Analysis of the Pump-turbine S Characteristics Using the Detached Eddy Simulation Method

Current research on pump-turbine units is focused on the unstable operation at off-design conditions, with the characteristic curves in generating mode being S-shaped. Unlike in the traditional water turbines, pump-turbine operation along the S-shaped curve can lead to difficulties during load rejection with unusual increases in the water pressure, which leads to machine vibrations. This paper describes both model tests and numerical simulations. A reduced scale model of a low specific speed pump-turbine was used for the performance tests, with comparisons to computational fluid dynamics（CFD） results. Predictions using the detached eddy simulation（DES） turbulence model, which is a combined Reynolds averaged Naviers-Stokes（RANS） and large eddy simulation（LES） model, are compared with the two-equation turbulence mode results. The external characteristics as well as the internal flow are for various guide vane openings to understand the unsteady flow along the so called S characteristics of a pump-turbine. Comparison of the experimental data with the CFD results for various conditions and times shows that DES model gives better agreement with experimental data than the two-equation turbulence model. For low flow conditions, the centrifugal forces and the large incident angle create large vortices between the guide vanes and the runner inlet in the runner passage, which is the main factor leading to the S-shaped characteristics. The turbulence model used here gives more accurate simulations of the internal flow characteristics of the pump-turbine and a more detailed force analysis which shows the mechanisms controlling of the S characteristics.

Analysis on the Temporal and Spatial Characteristics and Causes of Cold Wave in Qinhuangdao

[Objective] The aim was to study the temporal and spatial characteristics and causes of cold wave in Qinhuangdao.[Method] Based on temperature data from five surface meteorological stations in Qinhuangdao from 1970 to 2009 and the latest standards issuing cold wave early warning signal,statistical analysis on the temporal and spatial distribution of cold wave was carried out,and the causes were discussed preliminarily.[Result] From 1970 to 2009,the frequencies of blue and yellow cold wave in Qinhuangdao region were 2 334 and 105 times respectively,and cold wave occurred most frequently in Qinglong County and least frequently in Lulong County,which was related to the effects of underlying surface,latitude and altitude.Cold wave might happen from September to next May,and the earliest occurrence date was September 9,while the latest end date was May 26.In addition,the frequency of cold wave was the highest in January and lowest in May.From 1970 to 2009,blue cold wave occurred most frequently in 1972 and 1979 and least frequently in 1984,while the frequency of yellow cold wave was the highest in 1979 and lowest in 9 years.From decadal variation,cold wave appeared most frequently in the 1970s and least frequently in the 1990s.With the increase of temperature,the frequency of cold wave showed decrease trend,and the beginning date tended to postpone,while its end date advanced,and it showed that the changes of cold wave was mainly caused by climate warming.[Conclusion] The study could provide theoretical guidance for the meteorological disaster prevention and reduction and local agricultural service.

Analysis of vibration reduction characteristics and applicability of steel-spring floating-slab track

A coupled dynamics computation model for metro vehicles, along with a steel-spring floating-slab track, is developed based on the theory of vehicle-track coupled dynamics. Using the developed model, the influences of the thickness, length and mass of floating-slab, spring rate and its arrangement space, running speed, etc. on the time and frequency domain characteristics of steel-spring fulcrum force are analyzed. The applicability of steel-spring floatingslab track is discussed through two integrated example cases of metro and buildings possessing distinct natural vibra- tion characteristics. It is concluded that, it is quite significant, in the optimization modular design of the parameters of steel-spring floating-slab track, to take the matching relationship of both the amplitude-frequency characteristics of steel-spring fulcrum force and natural vibration characteristics of integrated structures into comprehensive consideration. In this way the expensive steel-spring floating-slab track can be economically and efficiently utilized according to the site condition, and at the same time, the economic losses and bad social impact resulted from the resonance during usage of steel-spring floating-slab track can be avoided.

AdaBoosting Neural Network for Short-Term Wind Speed Forecasting Based on Seasonal Characteristics Analysis and Lag Space Estimation

High accurary in wind speed forcasting remains hard to achieve due to wind’s random distribution nature and its seasonal characteristics.Randomness,intermittent and nonstationary usually cause the portion problem of the wind speed forecasting.Seasonal characteristics of wind speed means that its feature distribution is inconsistent.This typically results that the persistence of excitation for modeling can not be guaranteed,and may severely reduce the possibilities of high precise forecasting model.In this paper,we proposed two effective solutions to solve the problems caused by the randomness and seasonal characteristics of the wind speed.(1)Wavelet analysis is used to extract the robust components of time series and reduce the influence of randomness.(2)Based on the energy distribution about the extracted amplitude and associated frequency,seasonal characteristics of wind speed are analyzed based on self-similarity in periodogram under scales range generated by wavelet transformation.Thus,the original dataset is reasonably divided into subsest which can effectively reflect the seasonal distribution characteristics of wind speed.In addition,two strategies are given to optimal model structure and improve the forecasting accuracy:(1)The forecasting model’s lag space is approximately estimated by the Lipschitz quotient to improve the generality ability of the feedforward neural network.(2)The forecasting accuracy and model robustness are further improved by the wavelet decomposition combined with AdaBoosting neural network.Finally,experimental evaluation based on the dataset from National Renewable Energy Laboratory(NREL)is given to demonstrate the performance of the proposed approach.