Numerical simulation of underwater acoustical field with directional sources based on the normal modes model

In this paper, beamforming and normal modes method are combined to calculate the underwater acoustical field. Firstly, beamforming technology is used to form directional sources by controlling the phase and relative amplitude. Secondly, considering the ocean speed, surface and bottom boundary, the point source sound field is calculated based on the normal modes model. Then underwater acoustical field with directional sources is achieved by adding all point source field. Taken the 11 elements vertical linear array as an example, the special directional source is formed by chebyshev amplitude weighting, and then underwater acoustical field is calculated in the Munk profile of different grazing angles. The results indicate that beam grazing angle is very essential to its sound field, and changing the grazing angle can enhance the sound intensity of the shadow zone correspondingly

Pentafluorophenyl Transfer Reaction: Preparation of Pentafluorophenyl [60]Fullerene Adducts through Opening of Fullerene Epoxide Moiety with Trispentafluorophenylborane

Unlike the extensively studied perfluoroalkyl fullerene adducts, perfluorophenyl fullerene adducts are quite difficult to prepare by known methods. Trispentafluorophenylborane was found to react with fullerene epoxide to form the 1,2-perfluorophenylfullerenol. The method can be applied to both the simple epoxide C-60(O) and fullerene multiadducts containing an epoxide moiety. Single crystal X-ray structure analysis confirmed the addition of the pentafluorophenyl group

Car ownership and urban development in Chinese cities: a panel data analysis

Growth in car ownership has significant impacts on the use of urban space and management of urban environments, which makes it a topic of increasing interest especially for developing countries such as China. The dynamics of and factors influencing ownership in Chinese cities need careful investigation. Using fixed effects models applied to annual panel data (1994–2012; 293 cities) this study aimed to achieve the following: 1) assess the relationships between car ownership and average annual income per capita, population, built-up area, road area per capita, urban population density, number of taxis and bus passenger volume; 2) examine the variation of these relationships across geographical regions (East, middle, and West China) and city sizes (cities with small, medium, large, and super-large populations). The results showed that car ownership was positively associated with average annual income per capita, built-up area, road area per capita, urban population density, and number of taxis at the national level. All associations, except with the number of taxis, varied significantly across geographical regions. Built-up area, road area per capita, and number of taxis had different associations with car ownership depending on city sizes. The findings improve the understanding of relationships between car ownership and urban environments vis-a-vis variations in income and infrastructure per capita, population density, and transportation alternatives. These results have important policy implications for managing cars and health problems related to cars in China

Feature of Echo Envelope Fluctuation and Its Application in the Discrimination of Underwater Real Echo and Synthetic Echo

Discriminating a real underwater target echo from a synthetic echo is a key challenge to identifying an underwater target. The structure of an echo envelope contains information which closely relates to the physical parameters of the underwater target, and the characterization and extraction of echo features are problematic issues for active sonar target classification. In this study, firstly, the high-frequency envelope fluctuation of a complex underwater target echo was analyzed, the envelope fluctuation was characterized by the envelope fluctuation intensity, and a characterization model was established. The features of a benchmark model echo were extracted and analyzed by theoretical simulation and sea testing of a scaled model, and the result shows that the envelope fluctuation intensity varies with carrier frequency and azimuth of incident signal, but the echo envelope fluctuation of the synthetic target echo does not present these features. Then, based on the characteristics of echo envelope fluctuation, a novel method was developed for active sonar discrimination of a real underwater target echo from the synthetic echo. Through a sea experiment, the real target echo and synthetic echo were classified by their different echo envelope fluctuations, and the feasibility of the method was verified

Sulfide Rb-Sr, Re-Os and In Situ S Isotopic Constraints on Two Mineralization Events at the Large Hongnipo Cu Deposit, SW China

The Hongnipo deposit, a newly discovered large copper deposit in the Kangdian copper belt, SW China, is hosted in the Paleoproterozoic Hekou Group. This deposit contains ~4200 Mt of Cu ores, with an average grade of 1.42 wt.% Cu. Orebodies occur mainly as stratiform, stratoid and lenticular forms. Mineralization consists predominantly of high grade vein-type ores and low grade laminated ores. Field relationships indicate vein-type mineralization crosscuts laminated mineralization and host rocks, indicating that there were at least two mineralization events during the formation of the deposit. Pyrite separates from the laminated ores yield a Rb-Sr isochron age of 1552 ± 80 Ma, with a highly radiogenic initial 87Sr/86Sr ratio of 0.71214 ± 0.00081, indicating a major contribution from the ore-hosting rocks. Sulfides from the laminated ores have δ34S values ranging from −1.8‰ to 11.4‰, with the vast majority in the range of 5.3‰ to 11.4‰, suggesting the mixed derivation of sulfur from seawater sulfates and magmatic fluids. Chalcopyrite separates from the vein-type ores have a Re-Os isochron age of 794.8 ± 7.9 Ma. The initial 187Os/188Os (2.8 ± 1.2) and γOs (+2202) values are slightly lower than the average values of continental crust, indicating a major metal source of the Hekou Group with minor mantle input. Sulfides from the vein-type ores have δ34S values that range from −10.3‰ to 4.0‰ and cluster between 0‰ to 2.2‰, which implies a significant contribution of magmatic-sourced sulfur with minor biogenic sulfur. Two major mineralization events have been identified. The Rb-Sr age of the laminated ores likely records a VMS mineralization event at ~1.6 Ga. The much younger Re-Os age is considered to represent the timing of an important mineralization event, which is likely related to the Neoproterozoic magmatism and/or metamorphism and represents a newly documented mineralization event to be targeted by exploration

Pentafluorophenyl Transfer Reaction: Preparation of Pentafluorophenyl [60]Fullerene Adducts through Opening of Fullerene Epoxide Moiety with Trispentafluorophenylborane

Unlike the extensively studied perfluoroalkyl fullerene adducts, perfluorophenyl fullerene adducts are quite difficult to prepare by known methods. Trispentafluorophenylborane was found to react with fullerene epoxide to form the 1,2-perfluorophenylfullerenol. The method can be applied to both the simple epoxide C₆₀(O) and fullerene multiadducts containing an epoxide moiety. Single crystal X-ray structure analysis confirmed the addition of the pentafluorophenyl group

储藏条件对油莎豆及其油脂品质的影响Effect of storage conditions on the quality of tiger nut and its oil

为了探究不同储藏条件对油莎豆及其油脂品质的影响，将油莎豆在不同的温度(15、35 ℃)和湿度（11%、97%）下储藏40 d，测定油莎豆的含水量和含油量，以及油莎豆油的脂肪酸组成、维生素E含量和傅里叶红外光谱特征变化。结果表明：高湿（97%）条件下油莎豆含水量显著增加；低温低湿(15 ℃、11%）条件下油莎豆的含油量最高，为28.73%，高温高湿（35 ℃、97%）条件下最低，为26.82%；不同储藏条件下油莎豆油的脂肪酸组成没有显著变化，但高温和低湿储藏条件导致油莎豆油中饱和脂肪酸和多不饱和脂肪酸含量升高，单不饱和脂肪酸含量降低；油莎豆油中维生素E含量为171.34～183.80 mg/kg，主要成分为α-生育酚（117.70~126.12 mg/kg）和β-生育酚（40.55~45.38 mg/kg），相对于其他条件，高温低湿（35 ℃、11%）条件下油莎豆油中维生素E损失最严重；在试验考察范围内，储藏条件未对油莎豆油的官能团和结构产生明显影响。综上，选择适当的储藏条件有利于油莎豆的安全储藏。To investigate the effect of different storage conditions on the quality of tiger nut and its oil,tiger nut was stored at different temperatures (15,35 ℃) and humidity (11%, 97%) for 40 d, the moisture content and oil content of tiger nut, and fatty acid composition, vitamin E content and Fourier infrared spectral characteristics of tiger nut oil were determined. The results showed that the moisture content of tiger nut under high humidity (97%) conditions increased significantly. The oil content of tiger nut stored under the low temperature and low humidity (15 ℃, 11%) condition was the highest at 28.73%， and the lowest was 26.82% under the high temperature and high humidity (35 ℃, 97%) condition. Storage conditions had no significant effect on the composition of fatty acid of tiger nut oil,but high temperature and low humidity storage conditions resulted in higher saturated fatty acid and polyunsaturated fatty acid contents and lower monounsaturated fatty acid content in tiger nut oil. The vitamin E content of tiger nut oil ranged from 171.34-183.80 mg/kg， with α-tocopherol (117.70-126.12 mg/kg) and β-tocopherol (40.55-45.38 mg/kg) as the main components. The high temperature and low humidity (35 ℃, 11%) storage condition contributed to the most severe loss of vitamin E. Within the scope of the experiment, the storage conditions had no significant effect on functional group and structure of tiger nut oil. In summary,the selection of appropriate storage conditions can facilitate the safe storage of tiger nut

脱皮对油莎豆压缩特性的影响Effect of peeling on the compression characteristics of Cyperus esculentus

为探究脱皮对油莎豆压缩特性影响的内在机制，为油莎豆压榨制油工艺条件的制订和收获、运输、加工机械的改进提供数据支持，考察了油莎豆皮和仁在主要成分和微观结构上的异同，以及脱皮和未脱皮油莎豆在不同水分含量、压缩速率、压缩方位和颗粒大小下的压缩特性参数（位移、压缩力、破坏能和硬度）。结果表明：油莎豆仁和皮在主要成分和微观结构上存在很大差异，油莎豆仁的粗蛋白质、粗脂肪和淀粉含量分别为油莎豆皮的1.8、3.3倍和17.9倍；油莎豆仁的细胞呈蜂窝状，而油莎豆皮则呈片状；物性分析发现，与脱皮油莎豆相比，未脱皮油莎豆除具有破裂点还具有明显的屈服点；脱皮和未脱皮油莎豆压缩力范围分别为93.94~197.62 N 和103.45~245.14 N，硬度范围分别为23.45~43.70 N/mm 和24.27~53.02 N/mm；水分含量、压缩速率、压缩方位和颗粒大小等因素均对油莎豆的压缩特性参数具有显著影响，油莎豆压缩速率和颗粒大小与其压缩力和破坏能之间呈正向关系。脱皮后的油莎豆更容易发生压缩损伤，水分含量为15%的大颗粒未脱皮油莎豆不容易破裂，沿y轴方向低速率压缩更容易导致油莎豆受压损伤。 In order to explore the internal mechanism of the influence of peeling on the compression characteristics of Cyperus esculentus, and provide data support for the formulation of oil production process conditions and the improvement of harvesting, transportation and processing machinery, the compression characteristics (breaking force, distance, breaking energy and hardness) of the peeled and unpeeled Cyperus esculentus under different moisture content, loading rates, loading positions and particle sizes, as well as the similarities and differences of the skin and kernel of Cyperus esculentus in main components and microstructure were investigated. The results showed that there were great differences in main components and microstructure of the kernel and skin of Cyperus esculentus. The contents of crude protein, crude fat, and starch in kernel were 1.8, 3.3 times and 17.9 times as high as that in skin, respectively. The kernel cells were honeycomb-like, while the skin cells were lamellar. As revealed by texture analyzer, compared with peeled samples, unpeeled samples also showed conspicuous yield point in addition to the ruptured point. The ranges of breaking force and hardness of peeled and unpeeled Cyperus esculentus were 93.94-197.62 N, 103.45-245.14 N and 23.45-43.70 N/mm , 24.27-53.02 N/mm, respectively. Additionally, the compression characteristic parameters of Cyperus esculentus were significantly affected by moisture content, loading rates, loading positions and particle sizes. Moreover, there was a positive relationship between loading rates, particle sizes of Cyperus esculentus and its breaking force and breaking energy. Peeled samples are more prone to compressing damage, the unpeeled bigger Cyperus esculentus with 15% moisture content is not easy to crack, and the compression in the y-axis direction at low rate is more likely to cause the compression damage