08 May 2013, Volume 31 Issue 13
    

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  • HUANG Zhenli
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    The estimation of fish populations in certain waters is the basis of fishery resources management and conservation. The populations of Chinese sturgeon (Acipenser sinensis Gray) in the Yangtze River and its variation have received public attention and become a pending tough issue. Firstly, according to the features of reproduction population, the theory and method for estimating the populations of Chinese sturgeon in the Yangtze River from the year of 1981 to 1990 are established by using existing fishing data. It is indicated that between 1981 and 1990 there are 1,348 individuals on average with annual stock recruitment of 767 individuals in the Yangtze River. In addition, the estimation of Chinese sturgeon population and effects of fishing data are discussed, it is concluded that, (1) the theory and method for population estimation are feasible and of credibly accurate; (2) sensitivity analysis on the population estimation has been conducted; and (3) the level of resources utilization(fishing) has an obvious impact on both annual growth rate and immature individual scale factor for Chinese sturgeon.
  • YANG Shaohua;SHI Yaolin
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    Some ice caves exist in places where the yearly average ambient temperature is higher than zero centigrade. This phenomenon is quite rare. Ningwu Ice Cave in Shanxi Province is the largest ice cave of this kind in China. To explain the mechanism how the Ice Cave is preserved is a difficult scientific problem. In this paper, using the FEM (Finite Element Method) transient numerical calculation, the process of the heat transfer in the Ice Cave is simulated. We consider two controlling factors. Firstly, the external temperature is higher than the internal temperature of the Ice Cave in spring, summer or autumn. The air density increases in the gravity direction. So, there would be no convection in the Ningwu Ice Cave and the energy is transferred from the outside world to the Ice Cave by conduction. But in winter, the external temperature is lower than the internal temperature of the Ice Cave. The air density decreases in the gravity direction. Thus, the energy is transferred from the Ice Cave to the outside environment by convection. Secondly, the ice-water phase change prevents the external heat from being transferred to the internal Ice Cave. As the thermal convection is much more efficient than the thermal conduction, the heat inflow is much less than the outflow. The calculation results show that: (1) At a quasi steady state, the internal temperature of the Ice Cave is at the range of -3.9℃ to -2.9℃. That means that the ice body in the Ice Cave can be preserved. (2) If a sealed door is set at the Ice Cave entrance, the ice in the cave will melt within 40 years, because a sealed door can cut off the cold air into the Ice Cave in winter.
  • YANG Zhengming;FENG Cheng;LIU Xuewei;ZHU Dawei;TENG Qi;
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    The permeability stress sensitivity of the ultra-low permeability sandstone rock is experimentally studied in this paper. Unlike the 1D rock plug sample in the classical method, the 2D flat sandstone rock sample is used in this experiment and the synthetic formation water is used as the fluid medium. In addition, the permeability stress sensitivity of the 2D rock sample is compared with that of the conventional 1D rock plug sample. A novel research method for determining the rock permeability stress sensitivity is proposed. The experimental results indicate that the type of the fluid media and the size of the rock sample have a significant influence on the permeability stress sensitivity. The permeability stress sensitivity of the 2D flat rock sample is shown to be weaker than that of the conventional 1D rock plug sample. The relationship between the permeability and the effective stress of the 2D sample is close to that of the 1D plug sample when the brine is used as the fluid media. But it is different from that of the 1D plug sample when the nitrogen is used as the fluid media. The permeability stress sensitivity of the 2D sample is almost similar to that of the 1D plug sample in the lower effective stress range. However, the former is weaker than the latter in the higher effective stress range because the effective stress in the 2D sample is not uniform. The local permeability stress sensitivity at different sites is different from each other in the 2D sample. The effective stress has a more significant influence on the permeability in the main flow lines and the near production well regions.
  • LIU Xiaohua;
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    Due to the blocking of the screen section at the bottom of the tubing, the observed bottom-hole flowing pressure in the production wells of an over-pressured gas field might show an unexpected sudden drop, frequent fluctuations and some inconsistent changes with the flow rates, to mask the true behavior of the production wells. With the universal, everlasting poor quality of the flowing data, the identification of the abnormal data and the restoration of the true behavior are crucial in the well performance analysis. This paper proposes a simplified data diagnosis method based on the theory of the advanced production decline analysis and the PVT property of the over-pressed gas reservoir, to process the well production history data and to identify and filter the abnormal data. Then, the processed production data are analyzed through the type-curve matching to calculate the well and reservoir parameters, including the skin, the permeability, and the initial gas in the place. Based on these parameters, single well analytical models are built to generate the well true production history. In the end, the generated well production history is verified.
  • HU Yifu;LIU Longqiong
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    In order to protect the phosphate rock resources, it is important to optimize their usage. With the phosphorus productions in China, the United States and Morocco as examples, in three aspects including the country, the industry and the enterprise, this paper select ten indices reflecting the phosphate rock resource exploitation levels, including the phosphate rock foundation reserves, the average mineral taste, the mineral concentration and the mining cost, through the complex Analytic Hierarchy Process (AHP) to obtain the index weight vector, so as to establish a phosphate rock mining index comprehensive evaluation model, and using the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) to calculate the phosphate rock resource exploitation advantages for respective countries. It is shown that the phosphate production indices of China, the United States and Morocco based on the comprehensive dominance analysis are, respectively, 27.1%, 41.7% and 79.8%, thereby, the phosphate rock resource exploitation level of Morocco is the highest. This evaluation method result is reasonable and objective and practical, and can serve as a basis for the exploitation and protection of various resources.
  • LÜQiang;WANG Xiaolong;LIU Feng;NI Peipei
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    In view of the slow operation speed of the NARF algorism and the limitations of the extracting border feature, a new algorism is proposed to calculate the 3D NARF by using a local coordinate system with origin in the SIFT keypoint position. Firstly, the feature of the point cloud image is detected, a DoG3D operator is built to extract the 3D SIFT keypoints, then the feature of the keypoints is described, in a local coordinate system with origin in the keypoint position of the corresponding range image, the patches are projected to the design star shaped patterns with beams of equal angle interval within them according to the image resolution. The values of the descriptor vector elements are calculated by using the cells that lie under the beam, to form the given dimension descriptor. Finally, the experiments based on the point cloud obtained by the RGB-D sensor show that the algorithm can speed up the operation and the extracted feature is more general than that extracted by previous algorithms, by retaining more typical and distinct features of the descriptors.
  • WANG Dawei;WANG Wei;FENG Zhenyu
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    The airworthiness compliance method of civil aircraft engine life-limited parts is investigated, according to the needs of type forensics for civil high bypass ratio turbofan engine in China. Engine life-limited parts are rotor and major static structural parts whose primary failure is likely to result in a hazardous engine effect. Typically, engine life-limited parts include, but are not limited to, disks, spacers, hubs, shafts, high-pressure casings, and non-redundant mount components. The safety goals for the airworthiness requirement of aircraft engine life-limited parts in European and American are analyzed. The airworthiness compliance requirement for the life evaluation of engine life-limited parts in AC33.70-1 and AMC515 are analyzed and interpreted. The key process and method of aircraft engine life-limited part airworthiness conformity test are given. The model of safe life prediction for life-limited parts is founded. The proposed method provides an important reference for making airworthiness guide for aircraft engine life-limited parts.
  • WAN Suiren;CHENG Qian;HE Nongyue;LIU Bin
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    The nucleic acid detection workstation is a high-precision biochemical analytical instrument composed of optical, mechanical, electrical and other components. There are four functional modules in the workstation, including the high throughput magnetic separation system, the micro-volume pipetting system, the accurate temperature control system and the fluorescent signal detection system. According to the requirements of the above systems, a brief introduction is given for the framework of the hardware system. Based on the hardware functions, the software system completes the design of the experimental process using the tree control: an easy to use and good looking experimental property setting interface and a workbench layout with the MFC drawing. Serial communications are carried out through the slave PC's RSC-485 port with multi-threaded monitoring technologies: saving the experimental processes and results, exporting experimental data with the access database programming for their printing.
  • XIAO Yinong;CUI Yijiu;XU Qiong;WEI Na
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    This paper describes a kind of photosynthetic bacteria X1 from laboratory preservation. X1 has the ability to accumulate carotenoids naturally. The pigments were extracted by different methods to analyze the carotenoids' contents. Using morphological characters, physiological characters and 16s rDNA, X1 was identified. Then carotenoids were extracted by the ultrasonic extraction, acid-heat and grinding methods. Acetone was used as the solvent in the extraction. Furthermore, the ultraviolet spectrophotometry, the thin layer chromatography and the High Performance Liquid Chromatography (HPLC) system for the carotenoid extracts were analyzed. After appraisal, X1 was identified as Purple Non-Sulfur Bacteria, rhodospirillaceae, rhodopseudomonas, Rhodopsedomonas palustris. Comparing these extraction methods of carotenoids, it is shown that the ultrasonic extraction is the best method, followed by the acid-heat method. The grinding method is inferior to other two methods. As a result, Rhodopsedomonas palustris X1 can produce carotenoids up to 2.125mg/g (in dry weight) by the ultraviolet spectrophotometry at the wavelength of 495nm. The carotenoids have two main components, one of which is astaxanthin. The HPLC result shows that the astaxanthin content reaches 0.28mg/L in the extract.
  • WU Fuyong;WU Yukun;BI Yinli
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    A pot experiment was conducted to investigate the effects of inoculation of Glomus mosseae on the growth and nutrition uptake of Melilotus albus Desr. under water stress and/or phosphorus deficiency conditions. The pot trials include two levels of soil relative water contents (35% and 65%) and three levels of phosphorus (0, 25, 50mg·kg-1), either with inoculation of Glomus mosseae or without inoculation. The results show that the water stress does not inhibit the mycorrhizal infection of Melilotus albus. However, a high level of P in soils (50mg·kg-1) under water stress would significantly inhibit the mycorrhizal colonization. The inoculation of Glomus mosseae significantly increases the uptake of N and P in Melilotus albus and consequently alleviates the negative effects of Melilotus albus under water stress. The highest biomass of the shoot and the root of Melilotus albus is recorded in the treatments of inoculation in 50mg P·kg-1 soils. In addition, the inoculation of Glomus mosseae significantly enhances the coefficient of the water use of Melilotus albus under water stress or not. The results suggest that the inoculation of arbuscular mycorrhizal (AM) fungus may be a promising approach for increasing the growth of grass and enhancing the revegetation of the degraded grassland in arid and semi-arid regions.
  • LI Juan;GAO Na;ZHANG Jing;LI Li;XIAO Xiping;MA Bing
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    To investigate whether for elder patients with great thyroid neoplasm, the perioperative care can prevent complications, the nursing service of 28 elderly patients with great thyroid neoplasm treated in our hospital is analyzed. The complication rate is recorded and compared with the results reported in the literature. The recovery of 28 patients was good without serious complications, the incisions of all patients healed well, without post-operative bleeding and subcutaneous hematoma; no patients suffered from drinking cough; 2 patients suffered from hoarse throat, and came up with compensatory recovery after three to six months; 2 patients suffered from intermittent numbness of lips, and returned to normal after the calcium treatment; 1 case of pulmonary infection was improved after active treatment. These results are compared with cases in the literature and a low incidence of complications is clearly shown. It can be concluded that the appropriate nursing service can reduce the complication rate for the elder patients with great thyroid neoplasm.
  • Reviews
  • XU Qinkun;ZHOU Yuqin;TANG Zhonghua
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    Recently, in order to improve energy translation effect and decrease the emission of combustion byproducts, many researchers have gradually paid attention to enhance combustion and control combustion flame by utilizing an electric field. The effect of different electric fields, such as vertical electric field, horizontal (or radial) electric field, scattered (viz single electrode) electric field, and alternation electric field, etc, on various fuel combustion flame characters were firstly discussed. Secondly, the feasibility for decreasing combustion byproducts by using the electric field was described. Finally, up to now, the complete research on the relation between different electric fields and the combustion flame characters does not exist. Its relative base data, perfect mechanism analysis, and combustion reaction dynamics with electric field are lack of. Enhancing combustion and controlling combustion flame by utilizing various electric fields possesses the practical significance for saving energy and reducing emission.
  • WANG Weichao;LI Zhuangwen
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    Energy saving of buildings, which is directly related to national energy strategy, environmental protection, and sustainable development, is an important research topic. Energy-saving of external walls is the important research content of building energy-saving technology. Energy-saving technology on external walls mainly includes external thermal insulation technology of exterior walls, thermal insulation technology of inner walls, and self-insulation technology. The importance of thermal-insulating and energy-saving is analyzed and the main characteristics of two kinds of heat preservation technologies are discussed. Research advances in China are systematically introduced. And the considerations involving the insulation technology of building external walls are put forward.