Effects of artificial diet on the biological characteristics of the ladybeetle Coccinella septempunctata

Liu Chao,Liu Hongling,Wu Xinglong,Xiao Kejun,He Hengguo,Huang Qiong,Pu Deqiang 한국곤충학회 2022 Entomological Research Vol.52 No.4

The ladybeetle Coccinella septempunctata Linnaeus is an important natural enemy of aphids, scale insects, whitefly, and lepidopteran larvae. Mass rearing of this natural enemy is limited due to the lack of effective artificial feed. We compared the biological performance of C. septempunctata, reared on four artificial diets (A, B, C, and D), while the pea aphid Aphis craccivora served as a control treatment (CK). Results showed that the developmental time before emergence ranked from short to long follow as: CK (12.30d)<D(16.66d)<A(17.38d)<C (17.54d)<B (18.57d). The eclosion rate of larvae ranked from high to low follow as: CK (90.00%) > C (87.50%) = D (87.50%) > B(80.00%)> A (57.50%), and new adult weight from high to low follow as: CK (339.50 g*0.0001) > A (205.33 g*0.0001) > D (197.68 g*0.0001) > B (174.89 g*0.0001) > C (169.46 g*0.0001). The ratios of fecundity between the experimental group and the control group were 80.46% (A), 39.24% (B), 45.31% (C), and 53.02% (D). The hatch rates were 59.50% (A), 46.00% (B), 57.65% (C), 54.50% (D), and 53.88% (CK). The mortality of C. septempunctata adults fed on a combined artificial diet was higher than those fed on the control diet. Compared to the control diet, C. septempunctata did not significantly reduce oviposition when fed on artificial diet A. Therefore, diet A can be used in mass-rearing of C. septempunctata.

Experimental study on the wake characteristics of the circular cylinder with the V-groove surface

Liu Ping,Wang Deqiang,Yan Fei 대한조선학회 2022 International Journal of Naval Architecture and Oc Vol.14 No.1

In order to understand the wake characteristics for the circular cylinder with the V-groove surface, the Particle Image Velocimetry (PIV) and Proper Orthogonal Decomposition (POD) technology are used to measure and analyze the flow field velocity and the flow characteristic of the wake flow of the circular cylinder with the V-groove surface. This study focuses on the length of the velocity gradient, the Reynolds stress, the turbulent kinetic energy, the vortex shedding process, and the velocity fluctuating characteristics of flow field with POD technology. Compared with the smooth cylinder, the velocity gradient of the circular cylinder with the V-groove surface are larger. The peak values of Reynolds stress of the circular cylinders with the V-groove surface (the peak values are 0.33, 0.28 and 0.24) is lower than that of the smooth cylinder (0.39), and the peak values of turbulent kinetic energy are also lower. The recirculation region of the circular cylinders with the V-groove surface is larger, the length of the recirculation region are increased by 5.9%, 13.0% and 16.1% respectively, and it implies the suppression of vortex by the V-groove structure. Otherwise, the correlation of POD mode coefficients is disturbed for the circular cylinders with the V-groove surface, further proving that the effect of V-groove structure on vortex shedding.

Different Tribological Behaviors of SiCp/AZ91 Composites Induced by Tailoring the Distribution of SiC Particles

Huan Liu,Nannan Lu,Xiaojun Wang,Xiaoshi Hu,Deqiang Chen 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.3

In this study, the wear behaviors of the solution-treated and as-extruded SiCp/AZ91D metal matrix composites with differentsizes and volume fractions of SiC particles were systematically investigated under different wear test parameters. The SiCparticles exhibited a typical necklace-type distribution in the solution-treated composites and a homogeneous distributionin the as-extruded composites. Wear tests results showed that the wear rates of the as-extruded composites were lower thanthat of the solution-treated composites almost under all testing conditions and with the same SiC size and volume fraction. However, the dominant wear mechanisms for these two types of composites were different. The typical necklace-type distributionof SiCpin the solution-treated composites could effectively promote the occurrence of delamination owing to theweak bonding between SiCpand matrix in the particle aggregated regions. By contrast, as the bond between disperse SiCpand matrix was enhanced, the homogeneous distribution of SiCpin the as-extruded composites could promote the occurrenceof adhesion and prevent the occurrence of delamination. Moreover, a higher applied load and higher volume fraction of SiCpobviously promoted the progress of delamination for the solution-treated composites, while the extent of the adhesive wear forthe as-extruded composites was mainly associated with the increase of the applied load, sliding velocity and SiC particle size.

Filtration and regeneration behavior of polytetrafluoroethylene membrane for dusty gas treatment

Weidong Zhang,Deqiang Jiang,Junteng Liu,Zhongqi Ren,Wang Geng 한국화학공학회 2008 Korean Journal of Chemical Engineering Vol.25 No.4

With micron talcum particles and nano-CaCO3 powder as test dust, a series of experiments have been carried out to systematically study the gas filtration and regeneration behavior of polytetrafluoroethylene membrane, and some comparisons were made with common filter media. The experimental results showed that the PTFE membrane had a filtration efficiency of above 99.99% for micron particles, and excellent regeneration behavior was obtained, though a much higher initial pressure drop existed. Based on the results, it was concluded that the PTFE membrane is an excellent surface-filtration media for micron particles. Effects of operation parameters, including airflow velocity, particle concentration and particle characteristics were also investigated. To better understand the evolution of pressure drop during the filtration process, a mathematical model with operation parameters and characteristics of particles was derived from the gas-solid two-phase flow theories. A novel method on the determination of regeneration period of the filter media was put forward based on the analysis of the pressure drop according to this model

Nonfragile Sampled-Data Synchronization for Delayed Complex Dynamical Networks With Randomly Occurring Controller Gain Fluctuations

Zhang, Ruimei,Zeng, Deqiang,Park, Ju H.,Liu, Yajuan,Zhong, Shouming IEEE 2018 IEEE transactions on systems, man, and cybernetics Vol.48 No.12

<P>In this paper, the problem of nonfragile sampled-data synchronization of delayed complex dynamical networks with randomly occurring controller gain fluctuations (ROCGFs) is studied. First, more applicable nonfragile memory sampled-data controllers are designed, which involve the signal transmission delay and ROCGFs. The controller gain fluctuations appear in a random way, which obey certain Bernoulli distributed white noise sequences. Second, a modified piecewise Lyapunov–Krasovskii functional (LKF), which involves cubic sawtooth structure term, is constructed for the first time. Third, based on the LKF, less conservative synchronization criteria are established. In comparison with the existing results, the constraint condition of the positive definition of the LKF is less restrictive, since it does not need to be positive definite for all time, but is only required to be positive definite at sampling times. Finally, the effectiveness and advantages of the obtained results are illustrated by two numerical examples.</P>

Critical Short Circuit Ratio Analysis on DFIG Wind Farm with Vector Power Control and Synchronized Control

Hong, Min,Xin, Huanhai,Liu, Weidong,Xu, Qian,Zheng, Taiying,Gan, Deqiang The Korean Institute of Electrical Engineers 2016 Journal of Electrical Engineering & Technology Vol.11 No.2

The introduction of renewable energy sources into the AC grid can change and weaken the strength of the grid, which will in turn affect the stability and robustness of the doubly-fed induction generator (DFIG) wind farm. When integrated with weak grids, the DFIG wind turbine with vector power control often suffers from poor performance and robustness, while the DFIG wind turbine with synchronized control provides better stability. This paper investigates the critical short circuit ratios of DFIG wind turbine with vector power control and synchronized control, to analyze the stability boundary of the DFIG wind turbine. Frequency domain methods based on sensitivity and complementary sensitivity of transfer matrix are used to investigate the stability boundary conditions. The critical capacity of DFIG wind farm with conventional vector power control at a certain point of common coupling (PCC) is obtained and is further increased by employing synchronized control properly. The stability boundary is validated by electromagnetic transient simulation of an offshore wind farm connected to a real regional grid.

Quantized Sampled-Data Control for Synchronization of Inertial Neural Networks With Heterogeneous Time-Varying Delays

Zhang, Ruimei,Zeng, Deqiang,Park, Ju H.,Liu, Yajuan,Zhong, Shouming IEEE 2018 IEEE transactions on neural networks and learning Vol.29 No.12

<P>This paper is concerned with the problem of synchronization for inertial neural networks (INNs) with heterogeneous time-varying delays (HTVDs) through quantized sampled-data control. The control scheme, which takes the communication limitations of quantization and variable sampling into account, is first employed for tackling the synchronization of INNs. A novel Lyapunov–Krasovskii functional (LKF) is constructed for synchronizing an error system. Compared with existing LKFs by the largest upper bound of all HTVDs, the proposed LKF is superior, since it can make full use of the information on the lower and upper bounds of each HTVD. Based on the LKF and a new integral inequality technique, less conservative synchronization criteria are derived. The desired quantized sampled-data controller is designed by solving a set of linear matrix inequalities. Finally, a numerical example is given to illustrate the effectiveness and conservatism reduction of the proposed results.</P>

Critical Short Circuit Ratio Analysis on DFIG Wind Farm with Vector Power Control and Synchronized Control

Min Hong,Huanhai Xin,Weidong Liu,Qian Xu,Taiying Zheng,Deqiang Gan 대한전기학회 2016 Journal of Electrical Engineering & Technology Vol.11 No.2

The introduction of renewable energy sources into the AC grid can change and weaken the strength of the grid, which will in turn affect the stability and robustness of the doubly-fed induction generator (DFIG) wind farm. When integrated with weak grids, the DFIG wind turbine with vector power control often suffers from poor performance and robustness, while the DFIG wind turbine with synchronized control provides better stability. This paper investigates the critical short circuit ratios of DFIG wind turbine with vector power control and synchronized control, to analyze the stability boundary of the DFIG wind turbine. Frequency domain methods based on sensitivity and complementary sensitivity of transfer matrix are used to investigate the stability boundary conditions. The critical capacity of DFIG wind farm with conventional vector power control at a certain point of common coupling (PCC) is obtained and is further increased by employing synchronized control properly. The stability boundary is validated by electromagnetic transient simulation of an offshore wind farm connected to a real regional grid.

A new method for exponential synchronization of memristive recurrent neural networks

Zhang, Ruimei,Park, Ju H.,Zeng, Deqiang,Liu, Yajuan,Zhong, Shouming Elsevier science 2018 Information sciences Vol.466 No.-

<P><B>Abstract</B></P> <P>This paper investigates the exponential synchronization problem of memristive recurrent neural networks (MRNNs). A novel approach, switching matrix approach, is considered to study synchronization of MRNNs for the first time. All the matrices in the constructed Lyapunov–Krasovskii functional (LKF) are switching according to different switching rules. Based on the switching matrix approach, a new synchronization criterion is established in the form of linear matrix inequalities (LMIs). Compared with some existing methods, the switching matrix approach is more flexible and can improve the synchronization performance with low control cost. Finally, numerical simulations are provided to show the effectiveness and advantages of the proposed results.</P>

An International Comparison of the TFP Levels of Japanese, South Korean, and Chinese Listed Firms

Kyoji Fukao,Tomohiko Inui,Shigesaburo Kabe,Deqiang Liu 서울대학교 경제연구소 2008 Seoul journal of economics Vol.21 No.1

To compare the TFP level of firms in Japan, China, and South Korea, we first estimated the TFP of firms in each country using the method of Good, Nadiri, and Sickles (1997). Then we estimated the relative TFP by industry in the benchmark year using Japanese industries as benchmarks and combined the estimated TFP of firms. When estimating relative TFP by industry for South Korea and China, we applied the industry-level price estimates of the three countries from the ICPA project and converted industry outputs and inputs into the same currency unit (Japanese Yen). The estimation results obtained indicate that the productivity of Japanese firms is still higher than that of their Chinese and South Korean counterparts but that the productivity of South Korean firms is rapidly increasing, with the emergence of some firms that are now overtaking their Japanese rivals in terms of productivity, particularly in the electric machinery sector.