Experimental Study of the Relaxation Properties of Carbon Fiber Cloth.

In this study, a new method was proposed to study the relaxation properties of carbon fiber reinforced plastics (CFRP) fabric under axial tension. Under the condition of constant temperature and humidity, six groups of 168 h stress relaxation tests were conducted. Considering the influence of the prestress level, the size of CFRP cloth, and the surface coating of CFRP cloth on the relaxation performance, the measures to reduce the relaxation loss were proposed. The relaxation rate calculation model was established based on the test results of the authors and other scholars and was validated through comparisons with the test results. The results indicate that the relaxation rate of CFRP cloth was between 1.92% and 6.1%. When the prestress level was smaller than 0.3 fu, the relaxation rate of CFRP cloth decreased with the increase of prestress level. When the prestress level was greater than 0.3 fu, the relaxation rate increased with the increase of the prestress level. Under the same conditions, the relaxation rate of the CFRP specimens coated with glue was smaller than the uncoated samples by 3.21-6.28%. The calculation model could well estimate the relaxation rate of CFRP cloth.

[Evaluation of the clinical efficacy of implant-supported overdenture with edentulous mandible in elderly patients].

The aging society of the global population has led to an increase in the number of patients with edentulous jaw, a common multiple disease. Given the developments in implant techniques, the method of implant denture has received a positive and good response in terms of the quality of life and psychological well-being of patients. Implant-supported overdenture in mandible has two main advantages. 1) It has better retention and chewing efficiency than those of mandibular conventional denture. The required implant site of implant-supported overdenture is less than that of fixed implant-supported denture and can repair more defect tissues to help restore beauty and pronunciation. The price of the former is more acceptable than that of the latter. Therefore, this article aimed to systemically analyze and further discuss the clinical effect of implant-supported overdenture in elderly patients; combine existing related studies on the selection of number, site, and upper restoration of implants; and illustrate the advantages of removable implant-supported protheses in the repair of toothless mandible.

[Monitoring the total suspended matter of Lake Chaohu based on quasi-analytical algorithm].

There has been some effort by using quasi-analytical algorithm (QAA), which is based on radiative transfer theory to calculate backscattering coefficients of waters. A field investigation in Lake Chaohu was carried out in June, 2009, and a dataset including many parameters such as remote sensing reflectance, absorption and attenuation coefficients, concentration of total suspended matter (c(TSM)), had been obtained. Thereafter, a model for estimating c(TSM), was built, and in order to improve the accuracy, we employed the QAA algorithm to simulate backscattering ratio of Lake Chaohu. The results show that: 1) 807 nm and 834 nm are determined as optimum bands for the Two Near-Infrared Bands Method in Lake Chaohu, and the average specific scattering coefficient of suspended matters at the wavelength of 807 nm and 834 nm is 0.411 m2 x g(-1) and 0.395 m2 x g(-1) respectively; 2) The backscattering ratio of Lake Chaohu is 0.029, and better accuracy is achieved by using this value rather than other empirical values. The root mean square error (RMSE) and mean absolute percentage error (MAPE) of the estimated c(TSM) with calculated backscattering ratio are 12. 143 mg x L(-1) and 24.378%; 3) It is found that stations with high c(TSM) (nearly greater than 30 mg x L(-1)) can have more stable and reliable estimated results.

[Simulation of backscattering coefficients of inland waters].

When we simulated backscattering coefficients (b(bp)) using quasi-analytical algorithm and optical closure theory, it was found that the position of reference wavelength (lambda(0)) had great impact on final results. In order to identify influence factors of the optimum lambda(0), datasets of Lake Taihu, Lake Chaohu and Lake Dianchi were used. After simulating of b(bp), the relationship between optimum lambda(0) and associated water quality parameters were analyzed. Meanwhile, power functions were utilized to model b(bp) spectra, and spectral slope parameters of Lake Taihu, Lake Chaohu and Lake Dianchi were 2.643 +/- 0.317, 2.719 +/- 0.242, 1.638 +/- 0.534, respectively. The results indicate that: (1) When the whole lakes are taken as objects of study, the lambda(0) should be changed to longer wavelength with the increasing of total suspended particle matter concentration (c(SPM)), suspended organic particle matter concentration (c(SPOM)) and chlorophyll a concentration (c(CHL)), the optimum location of lambda(0) of Lake Taihu is 695 nm, Lake Chaohu is 720 nm and Lake Dianchi is 730 nm; (2) When the samples in lakes are taken as objects of study, the influence factors are different due to the complexity of optical properties of inland waters. But it is to be noted that, c(SPM) is a key factor in common. Besides, the regularity mentioned above should be weakened with high c(CHL). (3) The relationship between b(bp) and c(SPM) is much stronger in the waters with suspended particles dominated by inorganic particles, in Lake Taihu, for example, relationship between these two variables is strong with R2 = 0.852.

[Estimating of backscattering rate in Lake Chaohu based on bio-optical model].

Backscattering rate is the important factor of above water spectra. A bio-optical model simplified in near-infrared bands was constructed to estimate backscattering rate in Lake Chaohu by using the in-situ data measured in June 2009. The results show that the maximum value of backscattering rate in Lake Chaohu is 0.059, the minimum value is 0.001 4 and the mean value is 0.023 6. Backscattering rate and spatial differences in the west of Lake Chaohu are all greater than that in the east. In addition, particle refractive index of each sampling site was calculated by using backscattering rate. The dominant factors of in-water particles were determined according to the change scopes of refractive index. The results show that 74% of all sampling sites are dominated by inorganic particles, 18.5% of all sampling sites are dominated by both phytoplankton and inorganic particles, and the rest of sampling sites which accounts only for 7.4% of all sampling sites are dominated by phytoplankton. This indicates that backscattering character of Chaohu Lake is mainly affected by inorganic particles, while the effect of algae particle is relatively small.

[Spectral absorption coefficients of optically active substances in Lake Dianchi].

A field investigation in Lake Dianchi was carried out in November, 2009, and a dataset including absorption coefficients and concentration of water components was collected. Absorption properties and its spatial distribution of Lake Dianchi have been systematically analyzed, the results show that: (1) Absorption spectral curve of total particles (a(p)) are similar with that of phytoplankton (a(ph)), which indicates that phytoplankton absorption dominates absorption of total suspended particles; (2) Significant relationships are found between a(ph) (440), a(ph) (624), a(ph) (675) and concentration of chla, and cyanophyta dominats the quantity of the algae in water columns; (3) There are more phytoplankton existed in northern lake than other areas because of higher level of eutrophication. Comparing with other water columns, discrepancies mainly appear as below: (1) The mean value of slope of absorption spectral curve of non-algal particles (S(d)) in Lake Dianchi is much bigger than that in other case-II waters; (2) The mean value of slope of absorption spectral curve of chromophoric dissolved organic matter (CDOM) S(g) in Lake Dianchi is much smaller than that in other case-II waters; (3) Specific absorption of phytoplankton (a(ph)*) at 440 nm and 675 nm is at intermediate level, and a(ph)* value is susceptible to different regions, seasons, population structure of phytoplankton and so on.

[Preliminary exploring of hyperspectral remote sensing experiment for nitrogen and phosphorus in water].

The content of nitrogen and phosphorus in the waters is an important index to measure water quality, and the technique of remote sensing plays a large role in monitoring the change in environment. The reflectance spectra of nitrogen and phosphorus with different concentrations were measured to discover their special features under pure water condition in the laboratory by hyperspectral remote sensing technique. The result shows that nitrogen has reflectance peaks at 404 and 477 nm, and phosphorus at 350 nm, and these reflectance peaks have a good correlation with their concentrations, then a quantitative retrieval model was deduced for nitrogen and phosphorus based on that. These results will lay an important basis for further monitoring nitrogen and phosphorus by remote sensing technique in the big inland lakes, reservoirs and rivers.

[Evaluating eutrophic state of Taihu Lake by in situ hyperspectra].

In situ experiments including water quality analyzing and spectra measuring were conducted on Jun., 2004 and Aug., 2004 in Taihu Lake for 21 samples. Then eutrophic state of Taihu Lake was evaluated by measured hyperspectra data, and the evaluating index was eutrophic state index (TSI). Firstly, the simulation model of water reflectance was built by analytic model using inherent optical properties (IOPs). Then Chlorophyll a content (Chl-a) was inversed by optimizing method by Matlab software; Secondly, TSI was calculated by inversed Chl-a, and the eutrophic state of Taihu Lake was evaluated by using ArcView' s interpolation function. The evaluation figures show that: there are notable differences between Jun., 2004 and Aug., 2004. The proportion of mesotropher state is as high as 61% in June, while the proportion of light eutrophic is as high as 52% in August. In totally, the most serious eutrophic state occurs in north of Taihu Lake. Eutrophlic state wears off from north to south. The lowest eutrophic region is in the east of Taihu Lake.

[Integrated fuzzy evaluation of water eutrophication based on GIS in the Taihu Lake].

Supported by geographic information system and geostatistics, the application of fuzzy mathematics and analytic hierarchy process for water eutrophication evaluation was discussed. Taking Taihu Lake as an example, the research selected total phosphorus, total nitrogen, chlorophyll a, COD, BOD5, DO and transparence as evaluation index. After geostatistical analysis of the datum of monitoring site, the values of evaluation indices were estimated in the whole research area. Given that, the different dependence functions were developed for these indices and the function values were calculated. Furthermore, according to the principle of analytic hierarchy process, the weight of every index was calculated, then integrated evaluation value was obtained for the whole research area and the evaluation map for water eutrophication was drawn. The result shows that the level of nutrition is the highest in the north and north-west of lake, which is hypertrophic, that is meso-eutrophic in the middle and that is the lowest in the south-east of lake, which is mesotrophic.