A new description of the fractal dimension of particle aggregates in liquid medium

Xing, Jun,Ding, Shiqiang,Liu, Zhengning,Xu, Jirun Korean Association for Particle and Aerosol Resear 2015 Particle and Aerosol Research Vol.11 No.4

The possible existence forms of particle aggregates in liquid medium are classified into four different types according to their morphological characteristics, including the single particles that are separated from each other, the linear aggregates in which all component particles are located in a line, the planar aggregates where all particles are arranged on a plane, and the volumetric aggregates where all particles forms a three-dimensional space. These particle aggregates with different space morphologies have different fractal dimensions and different influence on the rheological phenomena of the solid-liquid system. The effects of various aggregates on the suspension viscosity are analyzed and related with the particle concentration, and then a mathematical model is presented to determine the fractal dimensions of various aggregates by measuring the apparent viscosity of the solid-liquid system. In the model, the viscous fractal dimension is developed as a new concept, the fractal dimensions of different aggregates can be obtained separately and then the relative components of various aggregates experimentally analyzed.

A Web-Based Domain Ontology Construction Modelling and Application in the Wetland Domain

Xing, Jun,Han, Min Korea Multimedia Society 2007 멀티미디어학회논문지 Vol.10 No.6

Methodology of ontology building based on Web resources will not only reduce significantly the ontology construction period, but also enhance the quality of the ontology. Remarkable progress has been achieved in this regard, but they encounter similar difficulties, such as the Web data extraction and knowledge acquisition. This paper researches on the characteristics of ontology construction data, including dynamics, largeness, variation and openness and other features, and the fundamental issue of ontology construction - formalized representation method. Then, the key technologies used in and the difficulties with ontology construction are summarized. A software Model-OntoMaker (Ontology Maker) is designed. The model is innovative in two regards: (1) the improvement of generality: the meta learning machine will dynamically pick appropriate ontology learning methodologies for data of different domains, thus optimizing the results; (2) the merged processing of (semi-) structural and non-structural data. In addition, as known to all wetland researchers, information sharing is vital to wetland exploitation and protection, while wetland ontology construction is the basic task for information sharing. OntoMaker constructs the wetland ontologies, and the model in this work can also be referred to other environmental domains.

A new absorbing foam concrete: preparation and microwave absorbing properties

Xingjun, Lv,Mingli, Cao,Yan, Li,Xin, Li,Qian, Li,Rong, Tang,Qi, Wang,Yuping, Duan Techno-Press 2015 Advances in concrete construction Vol.3 No.2

The foam concrete was fabricated by adding the foaming agent which composite ordinary Portland cement with plant and animal protein into cement paste, and the electromagnetic wave absorption properties were studied for the first time as well. The studies showed that the electromagnetic waves can be absorbed by multiple reflections and scattering within the porous material. Thickness and filling ratio have a great influence on the electromagnetic wave absorbing properties in 2-18 GHz of the foam concrete, the greater the thickness, the better the performance of absorption; filling ratio was about 52 vol.%, the absorbing properties achieved the best.

Heat transfer enhancement in cold plate based on FVM method and field synergy theory

Xingjun Hu,Yu Liu,Wei Yan,Jinglong Zhang,Jingyu Wang,Wei Lan,Tao Sang,Tianming Yu 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.5

To optimize the overall heat dissipation performance of the straight channel of a cold plate for lithium battery in vehicles, we used the wavy channel to optimize the structure and uses the face-centered central composite design (FCCCD), which takes the overall thermal-hydraulic performance factor as the response to explore the interaction mechanism of the flow field and temperature field in wavy channel of the cold plate. When the amplitude of the wavy channel is 1 mm and the number of cycles is 4, the overall thermal-hydraulic performance will reach its maximum with an increase of 17.4 % relative to the straight channel. Then, for the coolant, we explored the heat transfer performance of the nanofluid. The heat transfer coefficient of the nanofluid with a volume fraction of 2 % is 117 % higher than that of pure water and does not cause a significant increase in pressure drop.

Two-step continuous synthesis of tetraethylthiuram disulfide in microstructured reactors

Xingjun Yao,Lixiong Zhang,Changfeng Zeng,Chongqing Wang 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.3

Microstructured Reactor, N, N-diethyldithiocarbamic Acid, Tetraethylthiuram Disulfide, Vulcanization Accelerator,Strongly Exothermal

Efficient continuous epoxidation of biodiesel in a microstructured reactor

Xingjun Yao,Yan Zhang,Lingyun Du,Huiqiang Liu,Song Jiang 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.9

Efficient continuous epoxidation of biodiesel with peracetic acid generated in situ from hydrogen peroxide and acetic acid was studied in detail in a microstructured reactor. The effects of micromixer type, reaction temperature, catalyst usage, flow rate and residence time were considered. Results show the T-type glass micro-structured reactor (TTGMR) outperforms the interdigital multilamination micromixer. Under the optimized conditions, the final product from TTGMR has an epoxy value of 6.5 and an iodine value of 2.2.

Flow control of automobile with plasma vortex generator

Xingjun Hu,Jinglong Zhang,Zheng Hui,Yufei Luo,Peng Guo,Jingyu Wang 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.6

In this study, a plasma actuator was used to examine the wake flow control of an automobile with the aid of wind tunnel test methods, such as surface pressure measurement and particle image velocimetry (PIV) measurement. The control mechanism and law of the plasma vortex generator in the wake field of an Ahmed model were described. The effects of certain factors were analyzed. Results showed that the streamwise vortex induced by a dielectric-barrier-discharge vortex generator (DBD-VG) could promote the mixing of high-speed airflow above the slanted surface at the end of the model and low-speed airflow near the wall by increasing airflow turbulence, thereby inhibiting the generation of separation bubbles and reducing drag. Drag reduction decreased as the total discharge length of the DBD-VG decreased, but its backward distance had the largest effect on the drag reduction rate, followed by its counter distance. Meanwhile, the shortening of the streamwise length had the least effect on the drag reduction rate. When installing the DBG-VG, the end of the actuator should be arranged near the separation line to enable the generation and development of the streamwise vortex before the separation line to achieve the strongest flow control effect. The DBD-VG need not be arranged precisely at the airflow separation point, which demonstrates its favorable versatility. At low speeds, a maximum drag reduction rate of -8.51 % was obtained at an excitation voltage of 13 kV under the control of the DBD-VG, which demonstrated its strong flow control capability.

Aerodynamic drag reduction based on static traveling wave structure

Xingjun Hu,Zewei Wang,Jiuchao Li,Guo Yu,Jingyu Wang,Wei Lan,Jinglong Zhang,Pengzhan Ma 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.5

To explore the influence of the traveling wave parameters on the aerodynamic characteristics of Ahmed models, the geometric model of the traveling wave wall is used as the study object, and the influence of the traveling wave geometric parameters on aerodynamic drag is studied by numerical simulation. A cosine-type traveling wave digital model is established on the basis of Ahmed’s original model. Results show that the static traveling wave structure can play a good role in reducing drag under some driving conditions. The traveling wave’s drag reduction characteristics are affected by the layout position, depth, wavelength, and other related parameters and more affected by driving speed. Finally, a group of working conditions with good drag reduction effects is selected, and the principle of drag reduction by using static traveling wave structure is explained qualitatively and quantitatively through velocity field, shear stress, and pressure field.

Investigation on Electrical Enhanced Photocatalysis Polishing of Single-Crystal Silicon Carbide Substrates

Xingjun Gao,Xiang Li,Yan He,Lin Fan,Meiling Tang 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.23 No.11

In order to solve the problems of low efficiency, pollution and large damage of existing polishing methods, the electrical enhanced photocatalysis polishing method for single-crystal silicon carbide was proposed in this paper. The recombination of electrons and holes was inhibited by the combined action of applied electric field and chemical trapping agent, so the efficiency of oxidation was improved, and the polishing of silicon carbide with high efficiency and low damage can be achieved. The effects of various parameters such as polishing pressure, polishing speed, polishing pad, abrasive particles and oxygenation of slurry on polishing effect were studied. 0.025 MPa of polishing pressure, 60 r/min of polishing speed, 5 wt% of SiO2 abrasive particles and synthetic fiber polymer polishing pad can provide the higher MRR of 1.18 μm/h and the best surface quality (Ra = 0.348 nm). In addition, it has been proven that UV, optimized pH, types of photocatalysts, electron trapping agent and voltage are necessary factors for the slurry to exhibit strong oxidizing properties. The MRR is mainly determined by both mechanical action (introduced by abrasive particles) and chemical action (introduced by slurry). The above technology can basically meet the requirements of high-efficiency, ultra-smooth and low damage polishing of single-crystal silicon carbide.

DRAG REDUCTION PREDICTION OF AHMED MODEL WITH TRAVELING WAVE BASED ON BP NEURAL NETWORK

Hu Xingjun Hu,Jinglong Zhang,Yufei Luo,Jingyu Wang,Pengzhan Ma,Wei Lan,Chunbo Dong 한국자동차공학회 2022 International journal of automotive technology Vol.23 No.5

In this paper, a traveling wave model is proposed to explore its influence on the aerodynamic drag of a Ahmed model, the experimental and numerical results of aerodynamic drag coefficient CD for the Ahmed model are in good agreement. Then by defining the aerodynamic benefit coefficient ΔCD as the evaluation index for the orthogonal experiment, range analysis is conducted to determine the influences of the amplitude A, wavelength λ and frequency ω of the wave and the vehicle speed u on ΔCD. After the analysis it can been found that λ has the least importance among these parameters, hence A, ω and u are used to construct the 105 samples for training the BP neural network to predict ΔCD, results show that ΔCD obtained from the neural network is significantly affected by the parameters of traveling wave. The prediction accuracy of the network is furtherly verified by another 15 samples which are also built on A, ω and u, and the corresponding data overlap rate of ΔCD is 96 %, so it can be concluded that the BP neural network constructed in this paper is accurate enough to predict ΔCD.