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针对大气激光通信下的OFDM（正交频分复用）系统,对几种基于导频的信道估计方法进行了比较分析,并给出了仿真结果。仿真结果表明,SVD-LMMSE（基于奇异值分解的线性最小均方误差）算法在提高信道估计精度的同时,可以降低系统计算的复杂度;增大CP（循环前缀）可以非常有效地提高系统性能。

文章研究了波分复用（WDM）光网络中动态业务下的波长分配问题,在无波长转换器的条件下,提出了一种加入了公平性考虑的动态门限算法。该算法在支持多优先级的动态门限法的基础上,通过更新初始优先级减少了不同距离光路连接请求间的阻塞率差别,改善了公平性。计算机仿真结果说明了该算法的有效性。

To realize the rapid and accurate density assay of oil product, the vibration tube densitometer method and float type densitometer method which are two kinds of mainstream digital densitometer methods are compared and analyzed in terms of principle and usage process. The uncertainty assessment of 20° density of jet fuel is studied by BHDM-YM04 oscillating U-tube densitometer. The uncertainty of measuring repeatability, instrument accuracy, instrument control temperature precision and instrument resolution are 1.5×10-5, 2.3×10-4, 2.1×10-5 and 2.9×10-5g/cm³ respectively in the whole measurement process. The uncertainty of instrument accuracy is the most influential factor. Finally, the synthetic uncertainty is 4.6×10-4g/cm³. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Functional Materials / Gongneng Cailiao is the property of Chongqing Functional Materials Periodical Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Nonferrous Metals (Extractive Metallurgy) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Mining Magazine is the property of China Mining Magazine Co., Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal on Communication / Tongxin Xuebao is the property of Journal on Communications Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Railway Science & Engineering is the property of Journal of Railway Science & Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Northern Agriculture / Beifang Nongye Xuebao is the property of Journal of Northern Agriculture Editorial and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Experimental Technology & Management is the property of Experimental Technology & Management Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Prataculturae Sinica is the property of Acta Prataculturae Sinica Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The analysis of the long-term mechanism of rural ecological revitalization has set five indicators; government driving force, management sustainability, platform support, ecological awareness, and supervision and security. The analysis of the long-term mechanism of rural ecological revitalization in Henan Province has been carried out by combining statistical data with field survey. The results show that the level of economic development is an important factor affecting the long-term mechanism of rural ecological revitalization. The long-term mechanism of rural ecological revitalization is not affected by geographical location, but there are obvious differences between counties. The government has paid more attention to ecological revitalization and established a grass-roots implementation agency for ecological revitalization. However, there is much room for rural residents to improve their awareness of ecological civilization and ecological consciousness. The rural domestic waste treatment system is basically sound, while the domestic sewage treatment system is a prominent weakness. Propose the construction strategy of the long-term mechanism of rural ecological revitalization. [ABSTRACT FROM AUTHOR]

Copyright of International General Practice is the property of Omniscient Pte. Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Southwest China Journal of Agricultural Sciences is the property of Editorial Department of Southwest China Journal of Agricultural Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Hemp is usually divided into “drug hemp” and “industrial hemp”. Industrial hemp contains less than 0. 3% tetrahydrocannabinol（THC） and is mainly used in the textile sector. Hemp is a kind of natural bast fiber, whose fineness is similar to that of cotton fibers. It is a kind of fine fiber among common fibers. Hemp fabrics have a slender middle cavity inside, and many holes and gaps are distributed longitudinately, making hemp fabrics soft and comfortable to wear. Hemp fibers consist of cellulose and other non-cellulose colloids such as hemicellulose, lignin, pectin and wax, which must be removed by degumming to meet textile standards. Compared with other hemp, lignin content in hemp fibers is higher, and lignin has higher stability to acid, alkali, hydrogen peroxide and other oxidants, which increases the difficulty of degumming hemp. The existing degumming techniques mainly include biological, physical and chemical methods. The biological degumming process is simple and easy to operate, and environmental friendly, with low energy consumption; the effect on fibers is mild and does not cause excessive damage. But in the actual production, the strains that can produce specific enzymes are few, the enzyme activity and enzyme yield are low, and the production cost is high; the degumming process is difficult to control, degumming effect is not ideal, and the product quality is unstable, so in industrial production, it is necessary to be combined with other degumming methods to meet the quality requirements. Physical degumming is the use of mechanical force to separate and remove part of the gum on the fiber, including the mechanical method, the ultrasonic method, the steam explosion method and the low temperature plasma method. This kind of method is simple to operate and does not pollute the environment, but the degumming effect is poor, so it is often used as an auxiliary degumming means in actual production. A breakthrough has been made in the research on the chemical degumming method of hemp fibers. Researchers have simplified the degumming process of hemp fibers, improved the chemical degumming effect of hemp fibers to a certain extent, and reduced the pollution of degumming wastewater to the environment. But these new chemical degumming methods are not perfect, there are such problems as high cost, high energy consumption, difficult-to-control degumming process parameters and unstable product quality, so there is still a long way to go before their being put into practical industrial production on a large scale. On this basis, the paper summarizes three basic methods of degumming hemp: biological degumming mainly includes the traditional degumming by water and rain, and the modern biological degumming technology by extracting crude enzyme liquid and compounding enzyme. In addition to the mechanical method, ultrasonic method and steam blasting method, such physical degumming methods as the plasma oxidation and supercritical CO2 method used in recent years are also mentioned. Chemical degumming is mainly summarized in three aspects: new oxidation degumming, organic solvent degumming and using physical methods to enhance the effect of chemical degumming. Moreover, the green degumming process with low energy consumption and high efficiency is reviewed. By combining with the research results in recent years, it is found that the three degumming means have their own advantages, but they also have their own problems. Therefore, according to the characteristics of each degumming method, the combination of different degumming technology can often get better degumming effect. In future production, a variety of degumming means will be combined, and the physical degumming method will be used as pre-treatment in the early stage, and supplemented by enzyme or microbial further degumming to reduce environmental pollution. On the basis of the first two, the chemical method is appropriately used to completely remove gum in order to improve the product quality. [ABSTRACT FROM AUTHOR]

Copyright of Xinjiang Agricultural Sciences is the property of Xinjiang Agricultural Sciences Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Linen products are widely used in clothing home textiles and industrial textiles and are favored in the textile market for their excellent properties such as good moisture permeability antibacterial and anti-radiation properties. The key to improve the spinnability of flax raw materials and the quality of finished products lies in degumming and extracting high-quality hemp fibers. Traditional chemical degumming methods of flax involve complicated steps long production process and high labor intensity which is no longer in line with the current trend of efficient production in factories. The research and development of efficient and energy-saving oxidative degumming has attracted wide attention of researchers. In recent years degumming flax fibers with various oxidant systems has become a research hotspot. The main principle of oxidation and degumming is to use oxidizer to quickly degrade the colloid and complete the bleaching at the same time which can simplify the cooking-bleaching process in the traditional de-bonding process. At present alkaline hydrogen peroxide is the most commonly used flax oxidation degumming system sodium percarbonate is often used as bleach and dyeing agent in the textile industry while the TEMPO system and the NHPI system are more frequently used for selective oxidation of plant cellulose to prepare fibers with high carboxyl content of high added value. However no related application in degumming of hemp fibers has been reported. At the same time the differences of physical and chemical properties of the four oxidation systems have not been systematically studied. The four oxidation systems of alkaline hydrogen peroxide sodium percarbonate TEMPO system and NHPI system were used in this study. The results show that all the four oxidation systems can successfully realize the degumming of flax fibers. Compared with primary flax the collagen content of flax fiber lignin and pectin decreases significantly the change of polymerization and bundle fiber strength varies greatly and the fiber fineness and whiteness are greatly improved. Specifically in terms of the NHPI system the fiber polymerization degree is 572 the bundle fiber strength is 24.41 cN / tex and the pectin content is 1.67% and its fiber tensile performance is poor and the residual pectin content is high. As for the TEMPO system the fiber fineness is 8. 33 dtex the degree of aggregation is 1 086 the lignin content is 1.62% and the fiber fineness is satisfactory. However the residual lignin content is relatively high and the polymerization degree is relatively low. As regards the sodium supercarbonate system the fiber polymerization degree is 2 315 the beam line dimension strength is 63. 09 cN / tex the lignin content is 1.74% and the pectin content is 1.58% . Its fiber strength and elongation performance is satisfactory while the gum content of residual lignin and residual pectin is relatively high. As for the alkaline hydrogen peroxide system the fiber whiteness is 60. 6 the lignin content is 1. 29% and the pectin content is 1.09% . It has the lowest fibrous pectin content. By exploring the differences in the physical and chemical properties of flax fibers under the four oxidation degumming systems this paper provides a new idea for the selection of the oxidation system in the flax degumming process. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Petrochemical Universities / Shiyou Huagong Gaodeng Xuexiao Xuebao is the property of Journal Editorial Department Of Liaoning Shihua University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Functional Materials / Gongneng Cailiao is the property of Chongqing Functional Materials Periodical Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Agricultural Resources & Environment / Nongye Ziyuan yu Huanjing Xuebao is the property of Journal of Agricultural Resources & Environment Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Electric Drive is the property of Electric Drive Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Silk is the property of Zhejiang Sci-Tech University Magazines and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Ideological and political education is a key course to implement the fundamental task of establishing morality and cultivating people. By exploring the cooperation between the revolutionary memorial hall and universities to build a long-term operating mechanism of the “great ideological and political course”, we can break through the institutional barriers of cooperation among different units, promote the rational allocation of social resources and universities, achieve the combination of small ideological and political courses in Universities with large ones in society, optimize the ideological and political practice teaching curriculum system, and promote the better integration of red culture into ideological and political courses. This is not only conducive to the reform and innovation of the ideological and political course in universities, but also to provide a paradigm for the construction of the “great ideological and political course” practice teaching base. [ABSTRACT FROM AUTHOR]

In order to objectively record the history of the Journal of Xi’an Polytechnic University from 2017 to 2021,and provide reference for the future development of the journal, the achievements of the journal in academic and social effect in the past five years were combed, as well as a series of work measurements such as the special topics, service of discipline construction and talent training, optimization of editorial committee, right academic integrity, enhanced publication and editorial team building, etc.It is found in practice that in order to form a good quality rising trend, the first step is to change the self-styled idea of running journal and mobilize the endogenous power; secondly, we should adhere to the principle that “quality is the life of journal innovation and development”, improve the number of high-quality manuscript sources, strengthen the contact with scientific research workers, strengthen the publicity and promotion of academic achievements, and gradually improve the quality and academic influence of journal. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Northeastern University (Natural Science) is the property of Dongbei Daxue Xuebao and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Petrochemical Universities / Shiyou Huagong Gaodeng Xuexiao Xuebao is the property of Journal Editorial Department Of Liaoning Shihua University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Silk is the property of Zhejiang Sci-Tech University Magazines and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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Copyright of Journal of Food Safety & Quality is the property of Journal of Food Safety & Quality Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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Heroic model education is closely related to the party spirit cultivation of college student communist party mem⁃ bers in many dimensions. Heroic model education can provide practical efficiency, ideological effectiveness and development standards for the party spirit cultivation of college student communist party members. Although explorations have been made on the role of heroic education in cultivating the party spirit of college students, there are still shortcomings in terms of content con⁃ tinuity, cognitive propaganda, and collaborative development. In order to reverse the predicament and give full play to practical results, it needs to innovate the mechanism of the heroic model education so as to effectively escort the cultivation of party spirit among college student communist party members. [ABSTRACT FROM AUTHOR]

Copyright of Refractories / Naihuo Cailiao is the property of Naihuo Cailia (Refractories) Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Food Safety & Quality is the property of Journal of Food Safety & Quality Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Electroplating & Finishing is the property of Electroplating & Finishing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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Copyright of Advanced Engineering Science / Gongcheng Kexue Yu Jishu is the property of Advanced Engineering Science Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Control Theory & Applications / Kongzhi Lilun Yu Yinyong is the property of Editorial Department of Control Theory & Applications and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The traditional method of off-topic essay detection was mostly by transforming the text into vector space vector representation, then calculating the similarity between the correct text and the result of the problem. However, this method only took the representation of the sentence structure, yet neglected the semantic relevance of the article. And the off-topic essay detection result of high composition test was low. In view of the above problems, this paper proposed a method that used the topic and the text theme words in the coupling space to calculate its correlation degree, and then through the clustering method to realize the unsupervised composition test. The experimental results show that the composition test method based on the coupled space model has a certain degree of improvement to the essays with high divergence and low divergence, in which the composition of the topic with higher divergence is more obvious. [ABSTRACT FROM AUTHOR]