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Search Results: 1 - 10 of 1162 matches for " 鉴冉冉 "
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新型强化传热螺杆结构传热性能数值研究及场协同分析
王萌萌,谢鹏程,冉冉,赵世超,杨卫民
- , 2018, DOI: 10.13543/j.bhxbzr.2018.01.011
Abstract: 利用CFD软件fluent对普通螺杆结构和新型强化传热螺杆结构在塑化计量段中的三维非等温流场进行数值模拟,研究两种结构流道内熔体的速度场、轴向和径向温度场、对流传热系数及场协同角的不同。结果表明:在塑化过程中,新型强化传热结构存在着径向的对流传质过程,加强了径向的对流传热,因此有较好的径向温度分布;新型结构较普通螺杆结构有较高的对流换热系数和较好的场协同性,从而加强了螺杆的对流传热。
Abstract:Three-dimensional non-isothermal flow fields in the metering section of different screw structures during the plasticization process have been simulated by using CFD-fluent software, and the differences in velocity field, temperature field, radial temperature distribution, convective heat transfer coefficient and field synergy angle for the different screw structures are discussed. The results show that during the plasticization process, a new type of enhanced heat transfer screw structure affords radial mass transfer, thus enhancing the radial convective heat transfer, and the radial temperature distribution is also improved. Moreover, the new structure has a higher convective heat transfer coefficient and better synergy relationship than the conventional screw structure. The results show that there is a substantial improvement in the convective heat transfer of the screw in the case of the new design.
低剂量60Coγ射线辐照处理影响贮藏期鲜香菇保鲜效果
冉冉
- , 2018, DOI: 10.13982/j.mfst.1673-9078.2018.9.027
Abstract: 此项目研究低剂量60Coγ射线辐照处理对鲜香菇保鲜效果的影响。新鲜香菇分别使用0、1、1.5、2 kGy剂量进行辐照处理之后,贮藏于4±1 ℃、湿度为80±5%的环境,并对其微生物含量、组织硬度、色泽和相关的内源酶活性,例如,超氧化物歧化酶(SOD)、谷胱甘肽还原酶(GR)、苯丙氨酸解氨酶(PAL)、纤维素酶、几丁质酶品质指标进行测定。结果表明:1 kGy的照射剂量显着延迟(4~8 d)果实体软化和褐变的发生。在贮藏过程中,1 KGy照射剂量可以控制抗氧化系统中酶活性的降低,减少纤维素和几丁质的积累,并抑制蘑菇的老化。因此,1 KGy的60Coγ射线辐照能较好的保持香菇的品质特性,达到保鲜的效果。照射剂量在1.5 kGy以上会加快鲜香菇品质劣变。
This study examined the freshness-preserving effect of low-dose 60Co γ-ray irradiation treatment on the freshness of fresh mushrooms. Fresh Lentinus edodes were irradiated with 0, 1, 1.5 or 2 kGy dose, respectively, before being stored at 4±1 ℃ and humidity of 80±5%. Then, the microbial content, tissue firmness, color, and activities of enzymes (superoxide dismutase (SOD), glutathione reductase (GR), phenylalanine ammonia lyase (PAL), cellulase, and chitinase) were measured. Obtained results showed that the exposure to irradiation at a dose of 1 kGy significantly delayed (4~8 days) fruit softening and browning. During storage, the irradiation dose of 1 KGy can control the reduction of enzyme activity in the antioxidant systems, reduce the accumulation of cellulose and chitin, and inhibition the aging of the mushroom. Therefore, the 60Co γ-ray irradiation dose of 1 KGy can help preserve the characteristic quality of fresh mushrooms, but an irradiation doses above 1.5 kGy could accelerate the quality deterioration of fresh mushrooms.
电子器件散热器综合性能评估
Comprehensive Performance Evaluation of Electronic Device Radiator
 [PDF]

冉冉, 周俊杰, 李雪丽
Operations Research and Fuzziology (ORF) , 2016, DOI: 10.12677/ORF.2016.64013
Abstract:
本文运用模糊数学理论对翅片散热器的综合性能进行了探讨研究,使用MATLAB模糊工具箱对系统建立模型,模型实现当给出散热器的换热系数、热阻和压降值时,可以具体得到散热器的综合性能等级。结合具体实例,最后评判得出:分段翅片散热器的综合性能均优于平直翅片散热器的综合性能,本例中分段数为4的散热器综合性能最好。本研究对散热器综合性能的评判及选型具有一定的指导意义。
In this paper, the comprehensive performance of fin radiator is studied by the theory of fuzzy ma-thematics. The model is built with the help of MATLAB fuzzy toolbox, which has the following fea-tures: when the heat transfer coefficient, thermal resistance and pressure drop of the radiator are known, the comprehensive performance level of it can be obtained. The results elucidate that the discrete performance is better than that of the integrated and in this example, the best overall performance of the radiator is four of the subsection numbers. This research has certain directive significance to the comprehensive performance evaluation and selection of radiator.
随机提供水轮机大部件现场加工专用设备——供需观念的改变是发展的必然
Random Provide Turbine Large Component Field Processing Special Equipment——Supply and Demand of the Development of the Concept of Change Is Inevitable
 [PDF]

, 郭大川
Mechanical Engineering and Technology (MET) , 2013, DOI: 10.12677/MET.2013.21004
Abstract:
本文介绍了水轮机运行和修复概况以及国外目前水轮机修复改造中大件现场加工的苗头,引入制造厂随水轮机供货的同时提供大件现场加工专用设备的理念,从而缩短修复工期,取得良好经济效益,更有助于进一步提高水力资源利用率,达到节能减排的目的。
This essay introduces the operation and repair of turbine as well as the overseas sign of the big component in the turbine repair transformation processing. It brings the concept of providing large processing equipment at the mo- ment of supplying water turbine to shorten the repair time and expect better economic benefit. Furthermore, it helps to improve the utilization rate of water resources in order to achieve the purpose of energy saving and emission reduction.
以向日葵8号观测侦测过冲云的方法与实验
Methods and Experiments of Detecting Overshooting Top by Using Himawari-8 Imagery
 [PDF]


Advances in Geosciences (AG) , 2016, DOI: 10.12677/AG.2016.63022
Abstract: 本文以三种不同的方法,使用地球同步卫星向日葵8号的影像,进行侦测过冲云的测试,采用现有的水汽频道减红外窗区频道法与IRW-texture方法,并提供局地最小值法进行测试,此法结合上述二法的特点,但试图不要使用IRW-texture法中所需的数值预报的产品,且不要如水汽频道减红外窗区频道法,产生过多的过冲云像元。三个方法的实验结果与红绿蓝三色合成的侦测深对流产品、可见光和红外线色调强化影像比对,初步实验发现本文提供的局地最小值法是一个可行的尝试。
Detection of overshooting top experiments with three different methods has been conducted by using Himawari-8 data. We used the IRW-texture method and the algorithm based on different brightness temperature between water vapor and infrared window channel in this study. And we provided a local minimum method which combined the characteristic of both methods as men-tioned above. In this method, we tried to avoid using information from numerical weather forecast as in IRW-texture method. And we designed the method to minor false detection as the algorithm based on different brightness temperature between water vapor and infrared window channel. To estimate the accuracy of overshooting top detection algorithms, results from those methods have been compared with deep convection RGB image, visible image, and enhanced infrared imagery. In this primary test, the local minimum method shows its potential in detection of overshooting top.
以向日葵8号卫星观测侦测冰雪的初步实验
Primary Experiments of Detecting Snow and Ice by Using Himawari-8 Imagery
 [PDF]


Advances in Geosciences (AG) , 2016, DOI: 10.12677/AG.2016.65045
Abstract: 本文以NDSI (normalized difference snow index)进行雪地与海冰的侦测,以地球同步卫星向日葵8号的0.51微米与1.6微米频道计算NDSI,当NDSI大于0.6时视为海冰或雪地。但因有些种类的云,其NDSI值亦大于0.6,主要为云顶发展至高层的冰相云顶深厚云层,为区分此类与海冰/雪地光学性质类似的云,我们采用下列测试,以分辨地面冰雪覆盖区与此类的云。第一个测试:以1.6减2.3微米反照率的差值为判断标准,因为发现1.6微米减2.3微米的差值对于冰相云顶深厚云层时小于0,而对冰雪地面覆盖区时其值大于0。第二个测试:当7.3微米减6.2微米亮度温度小于设定阈值时视为冰相云顶深厚云层。第三个测试:当10.4微米减6.2微米亮度温度小于设定阈值时视为冰相云顶深厚云层。第二与三个测试是利用冰相云顶深厚云层为发展较高的云,而7.3微米减6.2微米或10.4微米减6.2微米亮度温度的差值随云顶高度的增加而减小。实验结果与红绿蓝三色合成的日间雪–雾影像产品比对,个案实验发现目前方法提供合理的冰雪侦测结果。
The normalized difference snow index (NDSI) has been used to detect sea ice and snow cover on the Earth. NDSI is calculated by using channel 0.51 μm and 1.6 μm on board geostationary satellite Himawari-8. The pixel is defined as ice/snow when the value of NDSI is higher than 0.6. However, the value of NDSI is higher than 0.6 for some type of cloud either. A primary type of this cloud is the thick cloud with ice top. In order to distinguish this type of cloud, following tests have been adopted to achieve this goal. First, we use the value of 1.6 μm minus 2.3 μm albedo as a parameter to distinguish between the ice/snow on Earth surface and the thick cloud with ice top because we found that the value of 1.6 μm minus 2.3 μm is positive for ice/snow on Earth’s surface and negative for thick cloud with ice top. Second, the pixel is not considered as ice/snow on Earth’s surface when the value of 7.3 μm minus 6.2 μm is smaller than a setting threshold. Third, the pixel did not define as ice/snow on surface of Earth if the value of 10.4 μm minus 6.2 μm is smaller than a setting threshold. The second and third tests are able to remove thick cloud with ice top by the fact that top of this kind cloud is higher than snow/ice on the Earth. Comparison of ice/snow map from NDSI with tests to snow-fog RGB image shows a relevant consistency between them.
古代DNA技术及其在家养动物驯化历史研究中的应用
冉冉,李宁
科学通报 , 2011, DOI: 10.1360/972010-1090
Abstract: 家养动物始终伴随着人类文明的发生、发展,其起源和驯化历史一直备受关注.而在其近万年的演化历史中,家养和野生群体间可能发生基因互渗及替代,因此基于现代物种DNA信息进行的历史推断可能存在偏差.近年来,古代生物遗骸中的DNA(古代DNA)获取技术日益成熟,为这类研究开辟了新的途径.本文总结了近年来古代DNA技术研究进展,点评了古代生物遗骸DNA的获取和鉴别方法、古代DNA提取、扩增及测序技术的革新.最后,本文综述了古代DNA技术在猪、马、羊、狗等主要家养动物驯化历史研究中的应用进展,为该技术的进一步发展及应用提供有益的参考.
2004年中国科技期刊出版统计

中国科技期刊研究 , 2005,
Abstract: 据新闻出版总署计划财务司统计,2004年全国共出版期刊9490种,平均期印数17208万册,总印数28.35亿册,总印张110.51亿印张,折合用纸量25.97万吨。与2003年相比,种数增长4.58%,平均期印数下降13.58%,总印数下降3.82%,总印张增长1.27%。
2005年中国科技期刊出版统计

中国科技期刊研究 , 2006,
Abstract: 据新闻出版总署计划财务司统计,2005年全国出版期刊9468种,总印数27.59亿册,总印张125.26亿印张。
1997年中国科技期刊出版统计

中国科技期刊研究 , 1998,
Abstract:
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