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Denitrification and phosphorus uptake by DPAOs using nitrite as an electron acceptor by step-feed strategies

Bin MA, Shuying WANG, Guibing ZHU, Shijian GE, Junmin WANG, Nanqi Ren, Yongzhen PENG

《环境科学与工程前沿（英文）》 2013年第7卷第2期页码 267-272 doi: 10.1007/s11783-012-0439-2

摘要： Denitrifying phosphorus accumulating organisms (DPAOs) using nitrite as an electron acceptor can reduce more energy. However, nitrite has been reported to have an inhibition on denitrifying phosphorus removal. In this study, the step-feed strategy was proposed to achieve low nitrite concentration, which can avoid or relieve nitrite inhibition. The results showed that denitrification rate, phosphorus uptake rate and the ratio of the phosphorus uptaken to nitrite denitrified (anoxic P/N ratio) increased when the nitrite concentration was 15 mg·L after step-feeding nitrite. The maximum denitrification rate and phosphorus uptake rate was 12.73 mg and 18.75 mg , respectively. These rates were higher than that using nitrate (15 mg·L ) as an electron acceptor. The maximum anoxic P/N ratio was 1.55 mg . When the nitrite concentration increased from 15 to 20 mg after addition of nitrite, the anoxic phosphorus uptake was inhibited by 64.85%, and the denitrification by DPAOs was inhibited by 61.25%. Denitrification rate by DPAOs decreased gradually when nitrite (about 20 mg·L ) was added in the step-feed SBR. These results indicated that the step-feed strategy can be used to achieve denitrifying phosphorus removal using nitrite as an electron acceptor, and nitrite concentration should be maintained at low level (<15 mg·L in this study).

关键词： denitrifying phosphate accumulating organisms (DPAOs) denitrification phosphorus uptake nitrite step-feed enhanced biological phosphorus removal

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Practical consideration for design and optimization of the step feed process

Shijian GE, Yongzhen PENG, Congcong LU, Shuying WANG

《环境科学与工程前沿（英文）》 2013年第7卷第1期页码 135-142 doi: 10.1007/s11783-012-0454-3

摘要： Based on the anoxic/oxic (A/O) step feed process, a modified University of Cape Town (UCT) step feed process was developed by adding an anaerobic zone and adjusting sludge return pipeline. Performance evaluation of these two types of processes was investigated by optimizing operational parameters, such as the anaerobic/anoxic/oxic volumes, internal recycle ratios, and sludge retention times, for removal of chemical oxygen demanding (COD), nitrogen, and phosphorus. Results showed high removal efficiencies of COD of (85.0±1.7)%, ammonium of (99.7±0.2)%, total nitrogen (TN) of (85.5±1.7)%, phosphorus of (95.1±3.3)%, as well as excellent sludge settleability with average sludge volume index of (83.7±9.5) L·mg in the modified UCT process. Moreover, (61.5±6.0)% of influent COD was efficiently involved in denitrification or phosphorus release process. As much as 35.3% of TN was eliminated through simultaneous nitrification and denitrification process in aerobic zones. In addition, the presence of denitrifying phosphorus accumulating organisms (DNPAOs), accounting for approximately 39.2% of PAOs, was also greatly beneficial to the nitrogen and phosphorus removal. Consequently, the modified UCT step feed process was more attractive for the wastewater treatment plant, because it had extremely competitive advantages such as higher nutrient removal efficiencies, lower energy and dosages consumption, excellent settling sludge and operational assurance.

关键词： step feed anoxic/oxic (A/O) University of Cape Town (UCT) simultaneous nitrification and denitrification (SND) denitrifying phosphorus removal biological nutrient removal (BNR)

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Field experiment on biological contact oxidation process to treat polluted river water in the Dianchi Lake watershed

Lu LI, Shuguang XIE, Hui ZHANG, Donghui WEN

《环境科学与工程前沿（英文）》 2009年第3卷第1期页码 38-47 doi: 10.1007/s11783-009-0007-6

摘要： In this study two types of biological contact oxidation processes (BCOP), a step-feed (SBCOP) unit and an inter-recycle (IBCOP) unit, were designed to investigate the treatment of heavily polluted river water. The Daqing River, which is the largest pollutant contributor to the Dianchi Lake, one of the most eutrophic freshwater lakes in China, was taken for the case study. It was found that the SBCOP had higher adaptability and better performance in the reduction of COD, TN, and TP, which made it applicable for the treatment of polluted river water entering the Dianchi Lake. Nitrification rate was observed to be greatly affected by the influent temperature. During each season, the nitrification in the SBCOP was higher than that in the IBCOP. TN removal efficiency in the SBCOP was higher than that in the IBCOP during the winter and spring but poorer during the summer, possibly due to the inhibition of denitrification by higher dissolved oxygen level in the summer. Moreover, symbiotic algae-bacteria growth may be conducive to the removal of pollutants.

关键词： step-feed biological contact oxidation process (SBCOP) inter-recycle biological contact oxidation process (IBCOP) river water removal efficiency nitrogen transformation the Dianchi Lake watershed

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Analysis of flow over backward facing step with transition

Dwarikanath RATHA,Arindam SARKAR

《结构与土木工程前沿（英文）》 2015年第9卷第1期页码 71-81 doi: 10.1007/s11709-014-0270-x

摘要： The present study deals with the study of the velocity distribution and the separation phenomenon of flow of air over a two dimensional backward facing step. The flow of air over a backward facing step has been investigated numerically using FLUENT. Flow simulation has been carried out in a backward facing step having an expansion ratio (ratio of the height before and after the step) of 1:1.94 and the results obtained are compared with the published experimental results. Comparison of flow characteristics between steps with three different transitions is made. The variation of reattachment length for all the three cases are analyzed for wide range of Reynolds number ranging from 100 to 7000 which covers the laminar, transition and turbulent flow of air. Simulation of the flow over steps with expansion ratios of 1:1.24, 1:1.38, 1:1.47, 1:1.53, 1:1.94, 1:2.20 are also carried out to examine the effect of different expansion ratios on the reattachment length. It is found that the primary reattachment length increases with increase in the expansion ratio. The primary reattachment length at the bottom wall downstream of the step is minimum for the step with round edged transition and maximum for the step with a vertical drop transition.

关键词： Reattachment length backward facing step transition flow separation k-? model

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Identification of thermal error in a feed system based on multi-class LS-SVM

Chao JIN, Bo WU, Youmin HU, Yao CHENG

《机械工程前沿（英文）》 2012年第7卷第1期页码 47-54 doi: 10.1007/s11465-012-0307-6

摘要：

Research of thermal characteristics has been a key issue in the development of high-speed feed system. The thermal positioning error of a ball-screw is one of the most important objects to consider for high-accuracy and high-speed machine tools. The research work undertaken herein ultimately aims at the development of a comprehensive thermal error identification model with high accuracy and robust. Using multi-class least squares support vector machines (LS-SVM), the thermal positioning error of the feed system is identified with the variance and mean square value of the temperatures of supporting bearings and screw-nut as feature vector. A series of experiments were carried out on a self-made quasi high-speed feed system experimental bench HUST-FS-001 to verify the identification capacity of the presented method. The results show that the recommended model can be used to predict the thermal error of a feed system with good accuracy, which is better than the ordinary BP and RBF neural network. The work described in this paper lays a solid foundation of thermal error prediction and compensation in a feed system.

关键词： least squares support vector machine (LS-SVM) feed system thermal error precision machining

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One-step synthesis of recoverable CuCo

Tongzhou Lu, Yongzheng Zhang, Chun Cheng, Yanbin Wang, Yongming Zhu

《化学科学与工程前沿（英文）》 2020年第14卷第4期页码 595-604 doi: 10.1007/s11705-019-1818-z

摘要： A facile one-step hydrothermal method has been adopted to directly synthesize the CuCo S material on the surface of Ni foam. Due to the relatively large specific surface area and wide pore size distribution, the CuCo S material not only effectively increases the reactive area, but also accommodates more side reaction products to avoid the difficulty of mass transfer. When evaluated as anode for Li-ion batteries, the CuCo S material exhibits excellent electrochemical performance including high discharge capacity, outstanding cyclic stability and good rate performance. At the current density of 200 mA·g , the CuCo S material shows an extremely high initial discharge capacity of 2510 mAh·g , and the cycle numbers of the material even reach 83 times when the discharge capacity is reduced to 500 mAh·g . Furthermore, the discharge capacity can reach 269 mAh·g at a current of 2000 mA·g . More importantly, when the current density comes back to 200 mA·g , the discharge capacity could be recovered to 1436 mAh·g , suggesting an excellent capacity recovery characteristics.

关键词： copper cobalt sulfide recoverability one-step hydrothermal method anode material Li-ion battery

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A deep feed-forward neural network for damage detection in functionally graded carbon nanotube-reinforced

《结构与土木工程前沿（英文）》 2021年第15卷第6期页码 1453-1479 doi: 10.1007/s11709-021-0767-z

摘要： This paper proposes a new Deep Feed-forward Neural Network (DFNN) approach for damage detection in functionally graded carbon nanotube-reinforced composite (FG-CNTRC) plates. In the proposed approach, the DFNN model is developed based on a data set containing 20 000 samples of damage scenarios, obtained via finite element (FE) simulation, of the FG-CNTRC plates. The elemental modal kinetic energy (MKE) values, calculated from natural frequencies and translational nodal displacements of the structures, are utilized as input of the DFNN model while the damage locations and corresponding severities are considered as output. The state-of-the art Exponential Linear Units (ELU) activation function and the Adamax algorithm are employed to train the DFNN model. Additionally, in order to enhance the performance of the DFNN model, the mini-batch and early-stopping techniques are applied to the training process. A trial-and-error procedure is implemented to determine suitable parameters of the network such as the number of hidden layers and the number of neurons in each layer. The accuracy and capability of the proposed DFNN model are illustrated through two distinct configurations of the CNT-fibers constituting the FG-CNTRC plates including uniform distribution (UD) and functionally graded-V distribution (FG-VD). Furthermore, the performance and stability of the DFNN model with the consideration of noise effects on the input data are also investigated. Obtained results indicate that the proposed DFNN model is able to give sufficiently accurate damage detection outcomes for the FG-CNTRC plates for both cases of noise-free and noise-influenced data.

关键词： damage detection deep feed-forward neural networks functionally graded carbon nanotube-reinforced composite plates modal kinetic energy

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论航空发动机发展的“渐改法”

温俊峰

《中国工程科学》 2000年第2卷第3期页码 23-26

摘要：

文章简要论述了航空发动机发展的两种途径及其特点，从国内外航空发动机改进发展广泛采用的作法和成功的经验事例，论证了“渐改”发展模式的规律性和重要性，提出了对发动机改进发展应加强组织领导和计划落实的建议。

关键词：航空发动机发动机发展途径渐改法

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一款基于改进的步进式译码算法实现的流水线架构RS码译码器 Article

Xing-ru PENG,Wei ZHANG,Yan-yan LIU

《信息与电子工程前沿（英文）》 2016年第17卷第9期页码 954-961 doi: 10.1631/FITEE.1500303

摘要：概要：基于改进的步进式译码算法，我们为超宽带系统设计了一款流水线架构的Reed-Solomon（RS）码译码器。为了减小复杂度，改进的步进式译码算法将传统步进式译码算法中冗余的两部分进行了结合。此外，采用流水线架构，使得所设计的译码器以最小时延获得最大吞吐率。因此，对于RS（23,17）码，我们所设计的译码器面积比ME（modified Euclidean）架构和pDCME（pipelined degree-computationless modified Euclidean）架构分别减少了42.5%和24.4%。此外，与传统步进式译码器相比，我们设计的译码器能减少11.3%的面积，且关键路径延迟更低。

关键词： Reed-Solomon码；步进式译码算法；超宽带；流水线架构

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INTERCROPPING: FEED MORE PEOPLE AND BUILD MORE SUSTAINABLE AGROECOSYSTEMS

《农业科学与工程前沿（英文）》 2021年第8卷第3期页码 373-386 doi: 10.15302/J-FASE -2021398

摘要：

Intercropping is a traditional farming system that increases crop diversity to strengthen agroecosystem functions while decreasing chemical inputs and minimizing negative environmental effects of crop production. Intercropping is currently considerable interest because of its importance in sustainable agriculture. Here, we synthesize the factors that make intercropping a sustainable means of food production by integrating biodiversity of natural ecosystems and crop diversity. In addition to well-known yield increases, intercropping can also increase yield stability over the long term and increase systemic resistance to plant diseases, pests and other unfavorable factors (e.g. nutrient deficiencies). The efficient use of resources can save mineral fertilizer inputs, reduce environmental pollution risks and greenhouse gas emissions caused by agriculture, thus mitigating global climate change. Intercropping potentially increases above- and below-ground biodiversity of various taxa at field scale, consequently it enhances ecosystem services. Complementarity and selection effects allow a better understanding the mechanisms behind enhanced ecosystem functioning. The development of mechanization is essential for large-scale application of intercropping. Agroecosystem multifunctionality and soil health should be priority topics in future research on intercropping.

关键词： agroecosystems ， crop diversity ，intercropping，interspecific interactions，sustainable agriculture

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Microplastics removal strategies: A step toward finding the solution

《环境科学与工程前沿（英文）》 2022年第16卷第1期页码 7-7 doi: 10.1007/s11783-021-1441-3

摘要：

Microplastics are an emerging threat and a big challenge for the environment. The presence of microplastics (MPs) in water is life-threatening to diverse organisms of aquatic ecosystems. Hence, the scientific community is exploring deeper to find treatment and removal options of MPs. Various physical, chemical and biological methods are researched for MPs removal, among which few have shown good efficiency in the laboratory. These methods also have a few limitations in environmental conditions. Other than finding a suitable method, the creation of legal restrictions at a governmental level by imposing policies against MPs is still a daunting task in many countries. This review is an effort to place all effectual MP removal methods in one document to compare the mechanisms, efficiency, advantages, and disadvantages and find the best solution.

关键词： Aquatic Coagulation Microplastics Plastic Water Treatment Plant Wastewater

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One-step synthesis of

Kuiyi YOU, Fangfang ZHAO, Xueyan LONG, Pingle LIU, Qiuhong AI, Hean LUO

《化学科学与工程前沿（英文）》 2012年第6卷第4期页码 389-394 doi: 10.1007/s11705-012-1218-0

摘要： A simple and efficient approach for the synthesis of -caprolactam via the liquid phase nitrosation of cyclohexane and nitrosyl sulfuric acid in the presence of concentrated sulfuric acid has been developed. A series of novel AlVPO composites were prepared by an impregnation method and the composites were then employed to catalyze the nitrosation reaction of cyclohexane and nitrosyl sulfuric acid. Compared to the reaction using fuming sulfuric acid, the selectivity for the desired product was significantly improved using this one-step catalytic process. This method affords a shortcut to prepare -caprolactam and its analogs from cyclohexane.

关键词： cyclohexane ?-caprolactam AlVPO composite catalysts one-step synthesis concentrated sulfuric acid

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FBRM and PVM investigations of the double feed semi-batch crystallization of 6-aminopenicillanic acid

Min SU, Lin WANG, Hua SUN, Jingkang WANG

《化学科学与工程前沿（英文）》 2009年第3卷第3期页码 282-288 doi: 10.1007/s11705-009-0018-7

摘要： 6-Aminopenicillanic acid (6-APA) is a crucial pharmaceutical intermediate in the chemistry of semi-synthetic antibiotics. The focused beam reflectance measurement (FBRM) technology and particle vision measurement (PVM) technology were employed to the processes of online-monitoring of 6-APA crystallization behavior in a double-feeding semi-batch crystallizer. Experiments were carried out with four kinds of double-feeding policies and the results were compared with the traditional single-feeding. Records and analysis of FBRM indicated that the nucleation of double feeding policy was much higher than single policy, and chord length of 6-APA was almost determined and had little change after the nucleation peak. Ostwald ripening process had no significant effect on further growth of 6-APA crystal. PVM images showed that the crystal habit of 6-APA was continuously changed during the crystallization process. The development of (002) face in the final crystal for the five feeding policies were different.

关键词： 6-aminopenicillanic acid crystallization double-feeding FBRM PVM crystal habit

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Comments on “Adaptation of Chinese and German maize-based food-feed-energy systems to limited phosphate

null

《农业科学与工程前沿（英文）》 2019年第6卷第4期页码 443-444 doi: 10.15302/J-FASE-2019288

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论我国饲料工业的标准化工作及其产品的质量管理

张子仪

《中国工程科学》 2001年第3卷第7期页码 30-36

摘要：

上个世纪末，我国饲料工业总产量比改革开放前增长了近70倍。1999年全国配合饲料合格率也从20世纪80年代的40%～60%提高到95.7%，这是一个巨大的成就。但目前饲料工业标准化工作则相对滞后。入世以后，我国饲料工业标准化体系将面临着与国际质量管理和质量保证标准的接轨以及与环境管理系列标准的配套问题。为此，在近期内应把握时机，及时作好我国饲料工业标准化工作水平的提高及更新换代。当前应重点抓紧饲料安全性标准的增删与修订。对饲料卫生标准、饲料原料标准、饲料质量监测技术及生物学效价评定等方面的标准必须全国统一；而对饲养标准则应因地制宜分类设置，根据具体情况可以跨省区设一类饲养标准，也可以在一个省或区设多种类型的饲养标准。

当前，饲料市场各个流通环节中的法制建设任务仍然十分艰巨。要坚决杜绝一切有损社会、生态效益的饲料添加剂进入市场；特别要严密监视国外活菌制剂类饲料及一切激素类饲料添加剂非法进入我国市场。要加强保护我国目前尚保留着的大面积净土；要为合法的、科学的饲料添加剂正名。这是争创“中国产绿色产品”品牌，提高我国饲料工业产品市场竞争能力的重要保证。

关键词：饲料工业标准化工作安全性国际环境管理系列标准饲养标准