Carbon-based electrode fabrication and performance of bioelectrochemical anaerobic digestion for sewage sludge

Qing Feng,Zhengkai An,Rusong Zhao,Xiaoli Wang,Jun Li,송영채 한국마린엔지니어링학회 2019 한국마린엔지니어링학회지 Vol.43 No.10

Bioelectrochemical anaerobic digestion (BEAD) is a technology which exploits the potential of microorganism by supplying a small amount of electric energy in an anaerobic digester. The electrode material is one of the most important parts of a bioelectrochemical system. For the anodes and cathodes of BEAD process, graphite fiber fabric (GFF), a carbon based material with good biocompatibility and non-corrosive property, was selected and its conductivity was modified by depositing carbon nanotube (CNT) via electrophoresis deposition (EPD) method. In the BEAD process, the organic matter in the reactor is oxidized on the surface of anode forming proton, carbon dioxide and electron. The electron produced is transferred to the cathode due to the potential difference between anode and cathode, followed by methane production on the surface of cathode resulting from the combination of carbon dioxide, electron and proton. The biochemical reactions at the electrodes can be controlled by the electrode potentials. When the potential between anode and cathode was maintained at 0.3 V using an external power supply, the BEAD reactor showed remarkable performance after the start-up period of 40 days. The performance of BEAD reactor was stable in terms of pH (7.2~7.5), alkalinity (4,500~5,200mg/L as CaCO3), methane content in biogas (77.3%) and volatile fatty acid levels (VFA < 250mg HAc/L). During steady state, the specific methane production rate and VS reduction were stabilized at 412 mL CH4/L.d and 72.5%, respectively, which were much higher than the conventional anaerobic digestion. The application of bioelectrochemical technology to anaerobic digestion provides a chance to overcome the disadvantages of conventional anaerobic digestion.

Electric field promotion of direct interspecies electron transfer for methane production in a bioelectrochemical reactor containing conductive materials

Qing Feng,Young-Chae Song 대한환경공학회 2019 대한환경공학회 학술발표논문집 Vol.2019 No.-

A New GARCH-Type Model

Qingfeng Liu 충남대학교 경영경제연구소 2010 경영경제연구 Vol.33 No.2

Liu와 Morimune(2005)는 일련의 양(+)의 충격 혹은 음(-)의 충격이 변동성에 미치는 영향을 포착하기 위하여 GARCH 모델을 확장하였다. 그리고 이 새로운 모델을 OGARCH 모델이라고 명명하였다. 그러나 OGARCH 모델에 대해 몇몇 연구자들이 충격의 함수형태에 문제가 있을 수 있음을 제기했다. 현재의 함수형태에서는 OGARCH 모델이 불안정할 수 있다는 것이다. 본 연구에서는 이러한 문제를 극복하기 위하여 충격에 대한 새로운 함수형태를 채택하여 모형을 수정하였다. 새로운 형태의 GARCH 모델은 일련의 양(+)의 충격 혹은 음(-)의 충격의 날짜 수가 변동성에 미치는 영향을 포착하도록 수정되었다. 본 연구는 새로운 모델을 SSEC, KS11, N225 지수들에 적용해 보았으며, 그 결과 상하이주식시장의 SSEC 지수를 분석하는데 특히 유용했음을 알 수 있었다. 또한 새로운 모형은 실증적 연구에서 OGARCH 모형과 GARCH 모형보다 더욱 좋은 결과를 보여주었다. Liu and Morimune (2005) expanded GARCH model to capture the effect of a consecutive number of positive or negative shocks on volatilities. They named that model OGARCH model. However, a shortcoming of OGARCH model on the function form was pointed out by some researchers. Due to this shortcoming, OGARCH model could be unstable. In this paper, in order to overcome this problem of OGARCH model, we modified it by adopting a different function of the spells of shocks. A new GARCH type model is established by means of capturing the effect on volatilities of the consecutive number of days of positive or negative shocks. The new model is applied to the SSEC, KS11 and N225 indices and is found particularly useful in analyzing the SSEC index of Shanghai market. Moreover, the new model performs better than OGARCH and GARCH model in the empirical study.

MSP1 triggers cell death and defense response in rice

Qingfeng Meng,Yiming Wang,Kyu Young Kang,Ravi Gupta,Sun Tae Kim 한국육종학회 2015 한국육종학회 심포지엄 Vol.2015 No.07

When the rice blast fungus attacks rice, fungal proteins are secreted into the plant apoplast to facilitate infection. The rice plant recognizes such secreted proteins, which result in the induction of defense responses. However, the molecular mechanisms of how rice plant recognizes secreted proteins remain elusive. Here, we report that a small, secreted protein, Magnaporthe oryzae snodprot1 homolog (MSP1), is recognized by rice plants and triggers host cell death and defense responses. Furthermore, pre-treatment of rice with Domain II, elicitor-active epitope of MSP1, induces resistance to the pathogen KJ301. We demonstrated that secretion of MSP1 into the apoplast is prerequisite for triggering cell death and activating defense-related gene expression, suggesting that it is recognized by a receptor in the host plasma membrane. Through comprehensively analysis of transcriptional profile in rice leaves and suspension cultured cells (SCCs) in response to exogenous MSP1 and Domain II treatment using 60K Agilent microarray chip, we found that 27 signaling genes, such as F-box(6), MAPK(4), protein kinase(11), transcription factor(6), were up-regulated in leaves and SCCs and six protein kinases were targeted into plasma membrane. Thus, we suggest that some of these genes may act as receptor of MSP1 in response to exogenous MSP1 treatment. Expression pattern of candidate genes was further checked in response to different environment cues using open rice data. These results demonstrate that these genes may be also involved in the signaling in response to cold stress, root-JA treatment and brown plant hopper (BPH) attack.

Developing Self-adaptive Software System : A Case Study

Qingfeng Zhang,Jing Xu,Chao Zhang 보안공학연구지원센터 2015 International Journal of Database Theory and Appli Vol.8 No.4

Current trends in software system, such as cloud and big data platform, are leading to rapid and continuing changes. At the same time, these systems will have to react to these changes at runtime to satisfy the potential Quality of Service (QoS). Self-adaptation is recognized as a practical way for a software system to meet QoS requirements. The Development of self-adaptive software is generally more challenging and more difficult due to their high complexity. To address these challenges, this paper reviews the related research of self-adaptive software system and reports a case study that investigates a self-adaptive concurrency controller for database system. Through the case we illustrate how to develop a self-adaptive software system. Compared with other traditional method, the experimental results demonstrate that our self-adaptive controller can effectively improve the database performance by adjusting the MPL value based on workload changes and QoS requirements. Finally some future trends in this area are prospected and discussed.

Asymptotical Outer Synchronization for the Controlled Complex Dynamic Networks with Unknown Bounded Interaction

Qingfeng Chen,Yinhe Wang,Xiao Tang 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.4

This paper investigates the problem of asymptotical outer synchronization for two complex dynamic networks (CDNs), one of which is called as the drive network and another is as the response network. Compared with the existing literature, the unknown bounded state interaction between the two CDNs is focused with the unknown and non-dissipative outer coupling configuration matrices of the drive-response networks, and thus the dynamic models of CDNs with interaction are proposed more general in structural form. Then, combined with the matrix analysis and Lyapunov stability methods, the relevant mathematical assumptions are proposed based on actual engineering background, with which the adaptive outer synchronization controller is synthesized in this paper. Therefore, the matrix straightening operation in the existing literature is avoided in this paper, which leads to the clearer structure of the designed controller. Finally, the effectiveness of the proposed method is verified by numerical simulation with the comparative example.

Study on Fast-Changing Mixed-Modulation Recognition Based on Neural Network Algorithms

( Qingfeng Jing ),( Huaxia Wang ),( Liming Yang ) 한국인터넷정보학회 2020 KSII Transactions on Internet and Information Syst Vol.14 No.12

Modulation recognition (MR) plays a key role in cognitive radar, cognitive radio, and some other civilian and military fields. While existing methods can identify the signal modulation type by extracting the signal characteristics, the quality of feature extraction has a serious impact on the recognition results. In this paper, an end-to-end MR method based on long short-term memory (LSTM) and the gated recurrent unit (GRU) is put forward, which can directly predict the modulation type from a sampled signal. Additionally, the sliding window method is applied to fast-changing mixed-modulation signals for which the signal modulation type changes over time. The recognition accuracy on training datasets in different SNR ranges and the proportion of each modulation method in misclassified samples are analyzed, and it is found to be reasonable to select the evenly-distributed and full range of SNR data as the training data. With the improvement of the SNR, the recognition accuracy increases rapidly. When the length of the training dataset increases, the neural network recognition effect is better. The loss function value of the neural network decreases with the increase of the training dataset length, and then tends to be stable. Moreover, when the fast-changing period is less than 20ms, the error rate is as high as 50%. As the fast-changing period is increased to 30ms, the error rates of the GRU and LSTM neural networks are less than 5%.

A Game theoretic analysis of public goods allocation in p2p networks

( Qingfeng Zhang ),( Sheng Wang ),( Dan Liao ) 한국인터넷정보학회 2015 KSII Transactions on Internet and Information Syst Vol.9 No.8

This paper presents a game theoretic approach to analyze the public goods (PGs) allocation in peer-to-peer (p2p) networks. In order to reduce the free-riders and promote the cooperation among peers, we propose an incentive mechanism with cooperation-based game theory. In this paper, we regarded the contributed resources by cooperators as public goods (PGs). We also build the PGs allocation in P2P networks to be the optimization problem, and the optimal solution of PGs allocation satisfies the Bowen-Lindahl-Samuelson equilibrium. Firstly, based on the subscriber mechanism, we analyze the feasibility and prove the validity, which can achieve Nash equilibrium. However, this strategy cannot meet to Bowen-Lindahl-Samuelson equilibrium as the free-riders do not pay with their private goods for consuming the PGs. Secondly, based on the Walker mechanism, we analyze the feasibility and prove the validity for the same allocation problem, which meets to Bowen-Lindahl-Samuelson equilibrium and achieves Pareto efficiency within cooperative game. Simulations show that the proposed walker mechanism can significantly improve the network performance of throughout, and effectively alleviate free-riding problem in P2P networks.

Mechanical Property and Microstructure of Fly Ash-Based Geopolymer Activated by Sodium Silicate

Qingfeng Lv,Jingjing Yu,Fengling Ji,Liuyang Gu,Yi Chen,Xiaokang Shan 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.5

Sodium silicate is one of the common alkali activators of geopolymers. The modulus, concentration and dosage of sodium silicate have significant effects on the activation of fly ash, the strength and microstructure of geopolymer. In this paper, unconfined compressive strength test, X-ray diffraction analysis (XRD), Fourier transform infrared light (FTIR), 29Si nuclear magnetic resonance (29Si NMR), scanning electron microscope and energy disperse spectroscopy (SEM-EDS), and physisorption experiment (BET) were carried out to study the effects of the sodium silicate modulus and dosage on the mechanical property and microstructure of fly ash-based geopolymer. The results indicated that the main product of the geopolymer activated by sodium silicate was hydrated sodium aluminosilicate (N-A-S-H). When modulus value decreased and meanwhile dosage of sodium silicate increased, the reorganization and polymerization of gel products were accelerated so that the integrity and continuity of the microstructure of geopolymer were improved, and then the strength increased. When the modulus of sodium silicate was 3.28, the maximum value of the strength was at the dosage of 10%. According to this study, it was investigated that modulus value and dosage of sodium silicate had obvious influence on the alkali- activated reaction of fly ash, which can provide an engineering reference for the special soil solidification with geopolymers.

Transcriptomic Analysis of Oryza sativa Leaves Reveals Key Changes in Response to Magnaporthe oryzae MSP1

Qingfeng Meng,GUPTARAVI,권순재,Yiming Wang,Ganesh Kumar Agrawal,Randeep Rakwal,박상렬,김선태 한국식물병리학회 2018 Plant Pathology Journal Vol.34 No.4

Rice blast disease, caused by Magnaporthe oryzae, results in an extensive loss of rice productivity. Previously, we identified a novel M. oryzae secreted protein, termed MSP1 which causes cell death and pathogen-associated molecular pattern (PAMP)-triggered immune (PTI) responses in rice. Here, we report the transcriptome profile of MSP1-induced response in rice, which led to the identification of 21,619 genes, among which 4,386 showed significant changes (P < 0.05 and fold change > 2 or < 1/2) in response to exogenous MSP1 treatment. Functional annotation of differentially regulated genes showed that the suppressed genes were deeply associated with photosynthesis, secondary metabolism, lipid synthesis, and protein synthesis, while the induced genes were involved in lipid degradation, protein degradation, and signaling. Moreover, expression of genes encoding receptor-like kinases, MAPKs, WRKYs, hormone signaling proteins and pathogenesis-related (PR) proteins were also induced by MSP1. Mapping these differentially expressed genes onto various pathways revealed critical information about the MSP1-triggered responses, providing new insights into the molecular mechanism and components of MSP1-triggered PTI responses in rice.