Applied Mechanics and Materials Vols. 316-317

Abstract: In this paper the purification performance of nitrogen and phosphorus in slightly polluted water by the combination of EM and submerged plants, Hydrilla verticillata was investigated. The results showed that the combination of EM and Hydrilla verticillata have a good purification effect on TN and TP in lightly polluted water, and the removal rate could reach to 70% and 97.3%, respectively. As compared with the treatments of aquatic plants and EM separately, the removal rate of TN and TP were increased by 23.4%, 2.1% and 23.4%, 41.3%, respectively.

Abstract: Low-carbon tourism is proposed as a new pattern to develop the global low-carbon economy, which goes with the tide in the global climate of change. Because tourism industry has a so close association with another industries that almost every link of tourism activities could be related to energy consumption and CO₂ emission. So, energy conservation and emission reduction constitute an important part of developing low-carbon tourism. This article selects GanSu Province, the weak ecological environment, as the research object. In accordance with the documents research and mathematical statistics , and the "bottom-up" study method., we made an research on energy consumption and the CO₂ emission of GanSu province from the tourism travel , tourism accommodation, and tourism activities, respectively. From the result, GanSu's tourism with low-carbon and energy-saving characteristics, accounting for 0.45% energy consumptions and 0.86% CO₂ emission in that of the GanSu's tourism. It shows that tourism fits in with the requirements of low-carbon tourism development. However, one of the most important factor in the tourism energy consumption and the CO₂ emission is the tourism transportation, accounting for 68.83% energy consumptions and 65.96% CO₂ emission in that of tourism respectively, which should be focus on as the key link in low-carbon tourism development.

Abstract: In order to reveal the harmful gas distribution characteristics of welding semi-closed field, this paper established a welding workshop model. Under conditions of natural and mixed convection, the flow state of CO generated in the welding process within the workshop was simulated based on the zero-equation turbulence model. The distribution of CO was analyzed under the conditions of different exhaust rate and different number of working welder. Studies have shown that higher concentration CO appears in the region of 0.6m to 1.5m from the ground; it is necessary to adjust the number of air vents when the number of welder is changing. In addition, the asymmetric structure of workshop also affects the distribution of CO. The simulation results not only can evaluate the pros and cons of the workshop structure and ventilation system, but also provide a theoretical basis for hazardous gas detection and alarm strategy for the further purposes.

Abstract: As cultural heritage tourism is widely regarded as a key element of promoting sustainable urban development and making a city competitive, allocating suitable budget for developing cultural heritage tourism thus becomes an important issue. Tainan City is an ancient cultural city with many cultural heritages, up to 112 attractions, in Taiwan. As the budget of local governments to promote tourism activities is limited, it is exceptionally important to assess the potential of cultural heritage tourism. Modified the cultural tourism assessment indicators proposed by Mckercher and Ho, this study assessed the potential of eight cultural heritage attractions in Tainan City by surveying visitors who have visited these attractions to verify the positioning of tourism development and to prioritize the resources for enhancing these attractions. The outcomes can provide a reference for decision-makers to promote sustainable tourism and allocate resources.

Abstract: Drought is a world-spread problem seriously influencing grain production and quality, the loss of which is the total for other natural disasters, with increasing global climate change making the situation more serious. Rice is the staple food for more than 23% of world population, so rice anti-drought physiology study is of importance to rice production and biological breeding for the sake of coping with abiotic and biotic conditions. Much research is involved in this hot topic, but the pace of progress is not so large because of drought resistance being a multiple-gene-control quantitative character. On the other hand, stress adaptive mechanisms are quite different, with stress degree, time course, materials, soil quality status and experimental plots, thus increasing the complexity of the issue in question. Additionally, a little study is related to weedy rice.In order to investigate the effects of drought stress on germination and early seedling growth of weedy rice (Oryza sativa f. spontanea L.) and cultivated rice (Oryza sativa L.), polyethyleneglycol-6000 (PEG-6000) are used to generate -1.33MPa and 0MPa water stress in a laboratory condition (28±3°C). Complete randomized design with three replications is used in the study. After 10 days of germination, shoot length, the longest root length, root fresh weight, root dry weight, shoot fresh weight, shoot dry weight and root numbers are measured; germination percentage, and root to shoot ratio are calculated. Germination index (GI), shoot length stress index (SLSI), root length stress index (RLSI) and dry matter stress index (DMSI) are used to evaluate the response of different genotypes to PEG-induced water stress. Results of ANOVA analysis show that responses of weedy rice accessions and cultivated rice varieties to water stress are significant different, demonstrating the germplasm of weedy rice and cultivated rice are diverse which enables us to screen the germplasm tolerant to drought stress.

Abstract: In this paper, the soil pollution condition of a typical chromium-containing slag heap in the North China plain were analyzed on the basis of previous data and the test during the field investigation. The hexavalent chromium content contour map was drawn. The regional soil chrome pollution level was evaluated by using single factor index method and potential ecological harm index method. The results of the single factor index method show that soil surrounding chromium-containing slag heap was seriously polluted. However, the results of the potential ecological harm index method evaluation show a slight pollution, which indicates that the area of chromium slag is not significantly harmful to ecology of the surrounding soil.

Abstract: Applying a combination of classical and geostatistical analysis, we investigated the distribution properties of soil water contents in broad-leaved Korean Pine forest (A) and secondary Polar-Birch forest (B) in Changbai Mountain, Northeast China. The results showed soil water content was significantly different between plots A and B (P < 0.05). The variation coefficient (CV) for soil water content was lower in plot A than in plot B at 0-10 cm depth, while the CV was higher in plot A than in plot B at 10-20 cm depth. Geostatistical analysis revealed that the exponential models were the optimality models for the soil water content in both plots. The spatial structured variance accounted for the largest proportion of total variance in soil water content in both plots. The autocorrelation range value for the semivariogram of soil water content was 8.9 m at 0-10 cm depth and 12.6 m at 10-20 cm depth in plot A, which was more than those in plot B (8.0 m) at both depths. Maps obtained by kriging showed that soil water contents in both plots exhibited different spatial distribution patterns. It could be conclude that the differences of rain time, precipitation form, topography and forest type may contributed to the distribution of soil water content in Changbai Mountain.

Abstract: A laboratory incubation experiment was performed to study the effects of three trophic level sediments with different nutrition status on the growth including physiological characteristics of Potamogeton crispus by embedding and suspension cultivation ways. The results showed: The high trophic level (HC) sediment was favorable for the early growth and the photosynthesis of Potamogeton crispus but unfavorable for the growth of roots. During the experiment, the POD activity rapidly increased to a maximum value under highly nutritious substrate in embedding groups. Later in the experiment, the content of soluble protein and chlorophyll decreased in the embedding group with HC sediments. To some extent, the normal growth of Potamogeton crispus was inhibited, while there wasn’t an apparente phenomenon that the decline of Potamogeton crispus.

Abstract: Autonomous surface vehicle provides a safe approach to monitor environment on water surface in dangerous condition. This paper presents a method of sea state detection from images taken by a camera fixed on an autonomous surface vehicle. Based on texture feature of images from water surface scene, gray level co-occurrence matrix is computed, and its features including energy, contrast, correlation and entropy are extracted. Experiments show that the contrast can differentiate the sea state levels better than the others. To improve discrimination at low sea state levels, a transform is proposed. Performance of the method at different light shining conditions is discussed, and the results validate the method.

Abstract: Abstract. In this study, the electrochemical treatment was used to block the leaching of alkali ions from concrete body, which would otherwise enhance the alkalinity of an aquatic environment and thus lead to a devastating contamination. The current density applied to the surface of concrete ranged 250, 500, 1000 mA/m2, and the duration of treatment was 1, 2, 4 weeks respectively. As a result, it was found that the treatment was effective in lowering the alkali leaching to an aquatic environment: an increase in the current density and duration of treatment resulted in a dramatic reduction of pH in the solution on the concrete surface. Its pH was reduced up to 8.33, whilst untreated concrete had a value of 12.91 in the pH. Simultaneously it is notable that the duration of treatment is a key shot to sustain the leachate blocking on the concrete surface. At the lower current density (250 mA/m2), the pH of the solution was eventually increased about 100 days after the completion of the treatment, while the pH at the highest current (1000 mA/m2) was mostly kept with no further increase.