Auto-parametric resonance of a continuous-beam-bridge model under two-point periodic excitation:an experimental investigation and stability analysis

The auto-parametric resonance of a continuous-beam bridge model subjected to a two-point periodic excitation is experimentally and numerically investigated in this study.An auto-parametric resonance experiment of the test model is conducted to observe and measure the auto-parametric resonance of a continuous beam under a two-point excitation on columns.The parametric vibration equation is established for the test model using the finite-element method.The auto-parametric resonance stability of the structure is analyzed by using Newmark's method and the energy-growth exponent method.The effects of the phase difference of the two-point excitation on the stability boundaries of auto-parametric resonance are studied for the test model.Compared with the experiment,the numerical instability predictions of auto-parametric resonance are consistent with the test phenomena,and the numerical stability boundaries of auto-parametric resonance agree with the experimental ones.For a continuous beam bridge,when the ratio of multipoint excitation frequency(applied to the columns)to natural frequency of the continuous girder is approximately equal to 2,the continuous beam may undergo a strong auto-parametric resonance.Combined with the present experiment and analysis,a hypothesis of Volgograd Bridge's serpentine vibration is discussed.

Investigation and Analysis of Main Diseases of Landscape Plants in the Main Urban Area of Lu'an City

To figure out the disease occurrence of landscape plants in the main urban area of Lu'an City,the author investigated the disease occurrence of landscape plants in park green space,residential green space,unit attached green space and main road in the area under administration.The survey results showed that there were 29 species of urban landscape plant diseases,mainly powdery mildew and spot diseases.According to the characteristics of the diseases,the causes and problems of the diseases were analyzed,and the corresponding prevention and control measures were put forward.

Investigation and Analysis of Understory Vegetation in Casuarina equisetifolia Forests in Northern Hainan Province

Understory vegetation in the Casuarina equisetifolia forests at different ages was sampled and analyzed fi rstly, and then the structural features, biomass, and distribution characteristics of carbon stock of the understory vegetation, as well as the quantity and thickness of the understory litter were studied. The results show that the understory vegetation in the C. equisetifolia forests is mainly composed of herbaceous plants, and there are nearly no shrubs in the study area. Moreover, the quantity of herbaceous plants rises obviously with the increase of forest age. There is a big difference between the woodlands at different ages in total biomass of herbaceous plants, and the maximum of total biomass can be found in 15-year-old woodland, reaching 1.68 t/hm^2; the biomass of overground parts of herbaceous plants is higher than that of underground parts. There is a big difference between the woodlands at different ages in thickness of the understory litter, and the thickness of understory litter in 10-yearold woodland is the highest, reaching 6.67 cm. The maximum quantity of the understory litter has reached 14.69 t/hm^2, and the thickness of the half decomposed litter is larger than that of the undercomposed litter in most woodlands.

Investigation and Analysis on the Present Situation of Indoor Formaldehyde Pollution in Residence of Binzhou City

As gradual improvement of living environment and indoor decoration form diversification, the indoor air pollution has become the ＂invisi- ble killer＂ harming human health, and has been listed as one of ten big threats to human health by the World Health Organization, which also be- came one of hot issues concerned by countries all over the world. In this paper, through the determination of formaldehyde in some houses of Binzhou, the release of formaldehyde with the increase of time was explored; change of formaldehyde in the same residence in different functional areas was analyzed; the influence of the temperature, humidity and plant to formaldehyde content was also analyzed.

Combination Use of PFGE and Drug-resistant Analysis in the Epidemiological Investigation of Listeria Monocytogenes

Listeria monocytogenes is the pathogen of listeriosis and it causes severe infections like septicemia, encephalitis, and meningitis, especially in immunocompromised individuals, newborns, and pregnant women. Its wide distribution in the environment and ability to survive or even grow under adverse conditions has made L. monocytogenes an important public health concern and in food industry.

Investigation and analysis of hazardous waste in the Three Gorges Area of Chongqing region

This article describes the investigation of hazardous waste (HW) in the Three Gorges Area of Chongqing region, which indicates that by May 2002, the dumped HW therein amounted to 14 600 t and was mainly distributed in five districts and counties with 11 000 t in Fuling, 1 650 t in Fengdu, 950 t in Wanzhou; 630 t in Wushan and 430 t in Yunyang. The total amount was composed of 9 670 t chromic residue, 2 310 t waste oil and residue, 410 t waste (false) fertilizer, 28 t waste chemical medicine, 26 t waste materials and 2 200 t other things including acid residue, waste asbestos, fluorine silicate, pigment, additive, waste acid, alkali, nitric acid, vitriol, lead mud, storage battery, calcium carbide, potassium cyanide, polluted soil, discard dynamite, waste packing barrel of cyanides, etc. In all of the HW, 578 t can be treated by chemical neutralization and stabilization technology such as redox, chemical precipitation, acid and alkali neutralization, etc., and the rest is temporarily untreatble and should be removed and piled at a temporary storage site above the 177 m water level of the dam with an aim to be transported to a future disposal site for innocuous treatment.

An investigation and analysis of the export earnings of 100 foreign trade enterprises in the first five months of this year

In order to understand the export situation faced by Chinese foreign trade enterprises and learn about their difficulties and problems in this regard, the China Association of Foreign Trade and Economic Cooperation Enterprises carried

Investigation and Analysis of Woody Landscape Plant Resources in Jinan City

To know the species composition, life form, seasonal features and application of woody landscape plants in Jinan City, woody landscape plants in the city were investigated comprehensively. The investigation shows that there are 535 woody landscape plant species in the city in total(including variants, subspecies and cultivars), belonging to 199 genera of 77 families. Among the 535 species, there are 49 gymnosperm species of 16 genera, 5 families, 486 angiosperm species of 183 genera, 72 families(including 467 dicotyledon species of 174 genera, 69 families, 19 monocotyledon species of 9 genera, 3 families). The fi gures refl ect rich woody landscape plants in Jinan City. There are 286 tree species, accounting for 53.4% of the total species; 216 shrub species, accounting for 40.4% of the total; 33 vine species, accounting for 6.2% of the total, thus tree and shrub species are diversifi ed, while vine species are limited. Among all tree species, there are 103 evergreen species, accounting for 19.25% of the total; 432 deciduous species, accounting for 80.75% of the total; so deciduous tree species occupy a prominent position. Woody plants in Jinan City are applied in diversifi ed forms, but seldom in innovative forms. Problems in the current application of woody landscape plants in the local area are summarized as(a) there are diversifi ed tree species, but only a few of them are applied in high effi ciency;(b) evergreen tree species are less used;(c) indigenous tree species are insuffi ciently used. Therefore, suggestions are given as(i) combine landscape plants scientifi cally;(ii) promote indigenous tree species;(iii) introduce and domestic new species actively. The investigation results provide scientifi c theoretical support for the sustainable utilization of woody plant resources in Jinan City.

Investigation and analysis of network psychology of college students

Based on basic situational research and analysis carried out on 638 college students using network, we found that as many as 20 percent of the students are not only largely dependent on internet, but also addicted to it. Further biography characteristics analyses for different individuals on the four dimensions of the network forced addiction, tolerance, and time management and interpersonal relationship and health, show that there are significant differences in grades, gender with different education levels of their parents. Further researches on discrepancy that addicted groups have in network entertainment addiction, network information, cyber porn, network relations and network transactions addictions also illustrate that significant discrepancies exist in gender, net age, different discipline and other factors. Finally we put forward some correlative measures to solve the problems of college students network psychology from individuals, schools, and society levels.

APPLICATIONS OF REMOTE SENSING IN ENVIRONMENTAL INVESTIGATION AND CHANGE ANALYSIS IN THE THREE GORGES AREA

1. INTRODUCTION The proposed Three Gorges Project, one of the biggest hydroelectric projects in the world, will dam the middle reaches of the Changjiang (Yangtze) River, the third longest river in the world, and form a large reservoir. Its impacts on environment have attracted wide attention. Entrusted by National Scientific-Technical Commission, the Chinese Academy of Sciences (CAS) was in charge of a research project on this issuse from 1984 to 1989. Tho use of remote sensing played an important role in the project considering the study area is mountainous and not convenientlv located, which makes it difficult to conduct the research onlv using conventional means.

Investigation and analysis of the job-hunting intentions and employment orientations of students majored in nursing

In recent years, China＇s employment problem of the college graduates has become a hot topic in the communities. Each year there are a large number of the graduating students, but few can find the job suitable for their own professional direction in colleges and universities. The employment problems have plagued the university graduates, and also have brought the unnecessary trouble to some students in the colleges. The college students have just entered the society, and they do not understand a lot of the social status very well, and have very little experience in the employment. In order to reduce the pressure of the employment of the university students, and help the graduate students bettor get employed, also to make the college students have a better planning for their future, in this paper, the author carried out the investigation and analysis of the job-hunting intentions and the employment orientations of the students majored in nursing, hoping to hclp the employment of the college students in some aspects, and do a good job in the planning of their career.

Investigation and Analysis on Agricultural Resources in the Main Living Areas of Pumi Nationality in Yunnan Province

[Objective] To fully grasp the living environment and the use of agricultural resources of Pumi nationality, a minority group specific in Yunnan. [Methods]Field investigation and analysis were conducted on the social economic conditions, living environment, types of agricultural resources and their use in the main inhabitances of Pumi people including Yulong, Ninglang, Lanping and Weixi County in Yunnan. [Result] There are certain differences in social and economic situations of the four counties, and the ecological environment is generally good. The main agricultural resources in villages under investigation include beans and coarse cereals, while there are certain differences among other agricultural resources due to their location. [Conclusion] The living environment of the main inhabitances of Pumi people in Yunnan is good and there are plenty and characteristic agricultural resources which have certain potentiality for development in the future.

Investigation of point defect evolution and Voronoi cluster analysis for magnesium during nanoindentation

The present study investigates the effect of nanoindentation on single-crystal magnesium specimens using the embedded-atom method potential in molecular dynamics simulation.Analyses are done under dynamic loading where the load-bearing capacity and change in the structural configuration are studied on the basal(Z-direction)and two prismatic planes(X-and Y-directions)with varying indenter velocities.The investigation of structural evolution is done using atomic displacement analyses to measure the net magnitude of displacement,atomic strain analyses to evaluate the shear strain developed in the process,and Wigner-Seitz defect analyses to calculate the total vacancies at varied timesteps.Furthermore,Voronoi analyses are done when indented on the basal plane to identify the cluster distribution at different planar depths of the specimen.From the analyses,it has been observed that the load-bearing capacity of the specimen varies with the indentation velocity and the direction of indentation on the specimen.Additionally,it is seen that the observed shear and total atomic displacement in the Z-direction is the least in comparison to the other two axes.The partial dislocation 1/3<-12-10>is seen to be majorly present and the population of dislocation loops is more abundant for lower indenter velocities.Furthermore,clusters<0,4,4,6>and<0,6,0,8>are the major indices developed during nanoindentation on the basal plane where they exhibit symmetrical distribution as observed from the Z-direction.

Investigation and Analysis of Continuous Cropping of Flue-cured Tobacco in Henan Province

The continuous cropping of flue-cured tobacco in the major producing areas of Henan Province by designing questionnaire, fieldwork, enquiry and phone calls, mails, and other forms, the data were obtained then classified and analyzed. The results showed that the main planting areas of flue-cured tobacco were in Nanyang, Xuchang, Luoyang, Sanmenxia, Pingdingshan, and Luohe where were the major producing areas of succession cropping of flue-cured tobacco with percentage of 20%-40% for three years and over three years, and a few places up to 50%. Morbidity was common with wide distribution, and the main diseases were black shank, viral disease, and black rot. It proved that tobacco was not suitable for continuous cropping. Both of tobacco disease and pest rate and mortality significantly increased by more than 40% under continuous cropping for three years and over three years, and the yield and quality of flue-cured tobacco also decreased after continuous cropping. For many places, the tobacco yield started to decrease in the second year of continuous cropping, and after three-year cropping, the yield decreased in the range of 9%-24%. Continuous cropping for a long time would make a serious decline in the quality of tobacco, resulting in non-economic benefits. Therefore, in order to reduce the occurrence of diseases and economic loss in tobacco production, it is recommended to avoid continuous cropping, or to adopt appropriate measures to control tobacco continuous cropping obstacles in the unavoidable case.

Research on the Current Status, Paths and Countermeasures of Family Farm Development in China——Investigation and Analysis of Hubei Province

The Chinese family farm is the most important new micro subject in the construction and development of modern agriculture in China. The investigation and analysis of the actual situation of Hubei Province showed that since the implementation of the household contract management system in rural areas, the family farm has followed the track of gradual development, breakthrough development and normal standardization development. In order to promote the family farm to develop rapidly, orderly and healthily, work must be well done to land circulation, scale management, financial support, financial subsidy, cultivation of leading talents and professional farmers, and providing all-round services.

Research status and prospects of the fractal analysis of metal material surfaces and interfaces

As a mathematical analysis method,fractal analysis can be used to quantitatively describe irregular shapes with self-similar or self-affine properties.Fractal analysis has been used to characterize the shapes of metal materials at various scales and dimensions.Conventional methods make it difficult to quantitatively describe the relationship between the regular characteristics and properties of metal material surfaces and interfaces.However,fractal analysis can be used to quantitatively describe the shape characteristics of metal materials and to establish the quantitative relationships between the shape characteristics and various properties of metal materials.From the perspective of two-dimensional planes and three-dimensional curved surfaces,this paper reviews the current research status of the fractal analysis of metal precipitate interfaces,metal grain boundary interfaces,metal-deposited film surfaces,metal fracture surfaces,metal machined surfaces,and metal wear surfaces.The relationship between the fractal dimensions and properties of metal material surfaces and interfaces is summarized.Starting from three perspectives of fractal analysis,namely,research scope,image acquisition methods,and calculation methods,this paper identifies the direction of research on fractal analysis of metal material surfaces and interfaces that need to be developed.It is believed that revealing the deep influence mechanism between the fractal dimensions and properties of metal material surfaces and interfaces will be the key research direction of the fractal analysis of metal materials in the future.

Investigation on the COVID-19 Outbreak in India: Lockdown Impact and Vulnerability Analysis

Coronavirus (COVID-19) disease is a major pandemic which has taken the world by storm. More than 524,000 citizens of the globe have succumbed to the disease as on 3rd July, 2020. Accurate modeling of the dynamics of the disease spread is required to curb the virus. With the availability of large amount of data made available publicly by the Government agency as well as the other live crowdsourcing media, it is possible to develop an accurate local prediction tool. In this study, we analyze the dynamics of local outbreaks of COVID-19 for few states of India with major outbreaks and for India as a whole. The large amount of data available from the COVID-19 Tracker India platform was utilized to estimate the impact of lockdown in the country and the states with major outbreaks. The effectiveness of the lockdown implementation by the respective states is studied for the analysis. The lockdown was categorized into strict, moderate, and lenient. The model is deployed on a web based platform to disseminate the alert to the public. We further extend the ordinary differential Equation (ODE) based model to generate district level vulnerability index for the whole country based on the rate of change of infected people, breach in social distancing, and population. Around 47% of districts of the country were not found vulnerable;however, 13% of the districts were identified as high risk for the disease outbreak.

Investigation of Punica granatum L.Germplasm Resources in Binchuan and Comparative Analysis of Major Fruit Qualities

[Objective] This study aimed to provide a basis for enriching the Punica granatum L. germplasm resources through investigating Punica granatum L. vari- eties in Binchuan. [Method] In this study, biological traits of Punica granatum L. vari- eties in Binchuan （including two local varieties-＇Binchuan Red Coat＇ and ＇Binchuan Green Coat＇, ＇Cyan Coat and Soft Seeds＇ and ＇Little Red Coat＇ introduced from Huili, Sichuan, ＇Acid Pomegranate＇ introduced from Shandong Province and ＂Ma Pomegranate＂ from Fengqiu, Henan） were investigated and their major fruit qualities were also analyzed. [Result] ＂Cyan Coat and Soft Seeds＇ and ＂Ma Pomegranate＇ grew well with good fruit quality, which adapted well to the climate and environment in Binchuan; ＂Little Red Coat＇ showed average performance in growth and major fruit qualities with inferior flavour; ＂Binchuan Red Coat＇ and ＇Binchuan Green Coat＇ also showed average performance in major fruit qualities and and inferior flavour; ＇Acid Pomegranate＇ grew while was inferior in flavour. [Conclusion] This study pro- vides references for presenting the directions for studies of P. granatum L. germplasm resources and determining the genetic relationship among germplasm resources, as well as breeding, introduction and cultivation of P. granatum L., further providing a variety basis for pomegranate production.

Investigation and Analysis on Production Cost of Guangxi Sugar Industry

Guangxi is the largest cane sugar production base in China,with more than 20 million sugar related personnel,and sugar related personnel account for about 50%of the total population in Guangxi.The development of cane sugar industry plays an important role in Guangxi and even the whole country.At present,there are still many difficulties and problems in Guangxi sugar industry,such as imperfect industrial chain,high industrial operation cost and weak comprehensive competitiveness.In this paper,by analyzing production cost of cane sugar,management cost,financial cost and cane consumption of sugar per ton in Guangxi,and starting from the problems in cane sugar production of Guangxi,development countermeasures of Guangxi sugar industry reducing cost and increasing efficiency under the new situation are put forward.

Epidemiological Investigation and Genome Analysis of Duck Circovirus in Southern China

Duck circovirus （DuCV）, a potential immunosuppressive virus, was investigated in Southern China from March 2006 to December 2009 by using a polymerase chain reaction （PCR） based method. In this study, a total of 138 sick or dead duck samples from 18 different farms were examined with an average DuCV infection rate of-35%. It was found that ducks between the ages of 40~60 days were more susceptible to DuCV. There was no evidence showing that the DuCV virus was capable of vertical transmission. Farms with positive PCR results exhibited no regularly apparent clinical abnormalities such as feathering disorders, growth retardation or lower-than-average weight. The complete genomes of 91 strains from Fujian Province and 1 from Zhejiang Province were sequenced and analyzed. The 10 DuCV genomes, comlbared with others genomes downloaded from GenBank, ranged in size from 1988 to 1996 base pairs, with sequence identities ranging from 83.2% to 99.8%. Phylogenetic analysis based on genome sequences demonstrated that DuCVs can be divided into two distinct genetic genotypes, Group I （the Euro-USA lineage） and Group II（the Taiwan lineage）, with approximately 10.0% genetic difference between the two types. Molecular epidemiological data suggest there is no obvious difference among DuCV strains isolated from different geographic locations or different species, including Duck, Muscovy duck, Mule duck, Cheery duck, Mulard duck and Pekin duck.