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Effect of carbon dioxide concentration on the combustion characteristics of boron agglomerates in oxygen-containing atmospheres

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2023年第11期24卷 949-959页

作者： Lian duan Zhixun xia yunchao FENG Binbin CHEN Jiarui ZHANG Likun MA College of Aerospace Science and Engineering National University of Defense TechnologyChangsha 410073China

In ramjet combustion chambers,carbon dioxide(CO_(2))produced by the combustion of carbonaceous fuel enters the chamber together with boron *** order to investigate the effect of CO_(2)concentration present in an oxygen-containing atmosphere on the combustion characteristics and oxidation mechanisms of boron agglomerates,we used a laser ignition system,an X-ray diffractometer(XRD),and a thermogravimetric-differential scanning calorimetry(TG-DSC)combined thermal analysis ***-particle boron was tested in the laser-ignition experiments as the control *** ignition experiment results showed that with a fixed O2 concentration of 20%,when the particle temperature reaches the melting point of boron,increasing CO_(2)content causes the combustion process of boron agglomerates to transition from single-particle molten droplet combustion to porous-particle ***,XRD analysis results indicated that the condensed-phase combustion products(CCPs)of boron particles in a mixed atmosphere of O2 and CO_(2)contained B4C,which is responsible for the porous structure of the *** temperatures below 1200℃,the addition of CO_(2)has no obvious promotion effect on boron exothermic ***,in the laser-ignition experiment,when the oxygen concentration was fixed at 20%while the CO_(2)concentration increased from 0%to 80%,the maximum temperature of boron agglomerates rose from 2434 to 2573 K,the self-sustaining combustion time of single-particle boron decreased from 396 to 169 ms,and the self-sustaining combustion time of boron agglomerates decreased from 198 to 40 *** study conclusively showed that adding CO_(2)to an oxygen-containing atmosphere facilitates boron reaction and consumption pathways,which is beneficial to promoting exothermic reaction of boron agglomerates at relatively high temperatures.

关键词： Boron combustion Amorphous boron Boron-containing propellant Solid fuel ramjet

Design and FPGA implementation of multi-wing chaotic switched systems based on a quadratic transformation

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Chinese Physics B 2021年第2期30卷 240-249页

作者： Qing-yu Shi xia Huang Fang yuan yu-xia Li College of Electrical Engineering and Automation Shandong University of Science and TechnologyQingdao 266590China

Based on a quadratic transformation and a switching function,a novel multi-wing chaotic switched system is ***,a 4-wing chaotic system is constructed from a 2-wing chaotic system on the basis of a quadratic ***,a switching function is designed and by adjusting the switching function,the number and the distribution of the saddle-focus equilibrium points of the switched system can be ***,a set of chaotic switched systems,which can produce 6-to-8-12-16-wing attractors,are *** Lyapunov exponent spectra,bifurcation diagrams,and Poincarémaps are given to verify the existence of the chaotic ***,the digital circuit of the multi-wing chaotic switched system is designed by using the Verilog HDL fixed-point algorithm and the state machine ***,the multi-wing chaotic attractors are demonstrated via FPGA *** experimental results show that the number of the wings of the chaotic attractors can be expanded more effectively with the combination of the quadratic transformation and the switching function methods.

关键词： quadratic transformation chaotic switched system FPGA

New insights into mercury removal mechanism on CeO2- based catalysts： A first-principles study

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Frontiers of Environmental Science & Engineering 2018年第2期12卷 107-115页

作者： Ling Li yu He xia Lu Forestry College Guizhou University Guiyang 550025 China Key Laboratory of High-Temperature and High-Pressure Study of the Earth's Interior Institute of Geochemistry Chinese Academy of Sciences Guiyang 550081 China State Key Laboratory of Organic-Inorganic Composites Beijing Advanced Innovation Center for Soft MatterScience and Engineering College of Energy Beijing University of Chemical Engineering Beijing 100029 China

First-principles calculanons were performed to investigate the mechamsm of Hg0 adsorpnon and oxidation on CeO2（111）. Surface oxygen acnvated by the reducnon of Ce to Ce a vlta to Hg~ adsorption and oxidation processes. Hg0 was fully oxidized by the surface lattice oxygen on CeO2（111）, without using any other oxidizing agents. HCI could dissociate and react with the Hg adatom on CeO2（111） to form adsorbed Hg CI or CI-Hg-Cl groups, which promoted the desorption of oxidized Hg and prevented CeO2 catalyst deactivation. In contrast, O-H and H-O-H groups formed during HC1 adsorption consumed the active surface oxygen and prohibited Hg oxidation. The consumed surface oxygen was replenished by adding O2 into the flue gas. We proposed that oxidized Hg desorption and maintenance of sufficient active surface oxygen were the rate-determining steps of Hg0 removal on CeO2-based catalysts. We believe that our thorough understanding and new insights into the mechanism of the Hg0 removal process will help provide guidelines for developing novel CeO2-based catalysts and enhance the Hg removal efficiency.

关键词： Elemental mercury removal Surface adsorption Ceria First-principles calculations

An optimized two-step derivatization method for analyzing diethylene glycol ozonation products using gas chromatography and mass spectrometry

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Journal of Environmental Sciences 2017年第3期29卷 313-321页

作者： Ran yu Lei duan Jingkun Jiang Jiming Hao State Key Joint Laboratory of Environment Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing 100084China State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex Beijing 100084China

The ozonation of hydroxyl compounds （e.g., sugars and alcohols） gives a broad range of products such as alcohols, aldehydes, ketones, and carboxylic adds. This study developed and optimized a two-step derivatization procedure for analyzing polar products of aldehydes and carboxylic acids from the ozonation of diethylene glycol （DEG） in a non-aqueous environment using gas chromatography-mass spectrometry. Experiments based on Central Composite Design with response surface methodology were carried out to evaluate the effects of derivatization variables and their interactions on the analysis. The most desirable derivati- zation conditions were reported, i.e., oximation was performed at room temperature overnight with the o-（2,3,4,5,6-pentafluorobenzyl） hydroxyl amine to analyte molar ratio of 6, silylation reaction temperature of 70℃, reaction duration of 70 min, and N,O-bis（trimethylsilyl）- trifluoroacetamide volume of 12.5 μL. The applicability of this optimized procedure was verified by analyzing DEG ozonation products in an ultrafine condensation particle counter simulation system.

关键词： Gas chromatography-massspectrometryResponse surface methodologyCentral Composite DesignDiethylene glycol ozonation

Microwave-assisted in situ synthesis of fluorescent gold nanoclusters with BSA/montmorillonite and application on latent fingermark imaging

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Science China Chemistry 2018年第5期61卷 619-626页

作者： Lei Yan Yanlin yu Zhining xia Forensic Science Engineering Research Center of Universities in Chongqing School of Criminal Investigation Southwest University of Political Science and Law School of Bioengineering Chongqing University

A method for in situ preparation of fluorescent gold nanoclusters(Au NCs) with bovine serum albumin/montmorillonite composite powder(Au NC-BSA/MMT) was developed, and the products were used to detect latent fingermarks. In this work, Au NCs were "grown" both inside and on the surface of BSA/MMT clay using one-step reduction of HAu Cl4 by BSA. The as-prepared Au NC-BSA/MMT nanocomposites emit intensive red fluorescence under the excitation of UV-visible light and show stable chemical features and low toxicity. The obtained fluorescent powders were characterized by UV-visible absorption spectroscopy,fluorescence spectroscopy, infrared spectroscopy, transmission electron microscopy/high-resolution transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction to depict their sizes, structural information and optical features. Given their environmentally friendly preparation, simple operation, low cost, efficient UVvisible radiation-dependent photoluminescence and good affinity with finger residues, the in situ synthesized Au NC-BSA/MMT nanocomposite powders were used as an alternative fluorescent developing reagent for developing latent fingermarks deposited on various object surfaces(such as glass, aluminum foil, painted metal, plastic products and weighing papers) for individual identification. As results, the developed fingermarks with clear patterns and satisfactory level-2(minutiae points) and level-3(sweat pores) ridge details were obtained. Notably, treated prints could be excited by red light and emitted near infrared fluorescence, which was beneficial to avoid background interference and reduce the damage caused by UV light. With the advantages of the simple preparation process and good enhancement performance for latent fingermarks, the proposed method might be used in the preparation of various fluorescent probes for detecting trace evidence in forensic sciences.

关键词： gold nanoclusters in situ montmorillonite latent fingermark fluorescent powder forensic science

Theoretical elastoplastic analysis for foundations with geosynthetic-encased columns

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2012年第7期13卷 506-518页

作者： yuan-yu duan Yi-ping ZHANG Dave CHAN Ya-nan yu College of Civil Engineering and Architecture Zhejiang UniversityHangzhou 310058China Department of Civil and Environmental Engineering University of AlbertaEdmontonAlbertaCanada

As a new technique in ground improvement, geosynthetic-encased columns (GECs) have promising applications in soft soil foundation. By assuming yielding occurs in the columns while the surrounding soil and the geosynthetic remain elastic, an elastoplastic analytical procedure for foundations improved by GECs is proposed. The radial stresses that the geosynthetic provides and the elastoplastic deformations of the foundation resting on a rigid base are derived. A comparison with finite element analysis shows that the proposed method is effective and can provide a reasonable prediction of a GEC's deformation. Subsequent parametric analysis indicates that higher geosynthetic stiffness leads to better performance of the composite foundation. The optimum length of encasement is related to the load acting on the foundation and the permissible vertical and radial displacements of the column. Moreover, as the dilation angle of the column increases, the settlement decreases, especially under high loading. The influence of the encasement is more significant in soils with smaller elastic modulus.

关键词： Geosynthetic-encased columns (GECs) Equal vertical strain Elastoplastic deformation Analytical procedure

Efficient hybrid neural network for spike sorting

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Journal of Systems Engineering and Electronics 2013年第1期24卷 157-164页

作者： Hongge Li Pan yu Tongsheng xia School of Electronics Information Engineering Beihang University

Artificial neural network has been used successfully to develope the automatic spike extraction. In order to address some of the problems before the wireless transmission of the implantable chip, the automatic spike sorting method with low complexity and high efficiency is proposed based on the hybrid neural network with the principal component analysis network （PCAN） and normal boundary response （NBR） self-organizing mapping （SOM） net- work classifier. An automatic PCAN technique is used to reduce the dimension and eliminate the correlation of the spike signal. The NBR-SOM network performs the spike sorting challenge and improves the classification performance. The experimental results show that based on the hybrid neural network, the spike sorting method achieves the accuracy above 97.91% with signals contain- ing five classes. The proposed NBR-SOM network classifier is to further improve the stability and effectiveness of the classification system.

关键词： neural network spike sorting implantable microsys-tern.

Output Feedback for Stochastic Nonlinear Systems with Unmeasurable Inverse Dynamics

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International Journal of Automation and computing 2009年第4期6卷 391-394页

作者： Xin yu Na duan School of Automation Southeast University Nanjing 210096 PRC Institute of Automation Qufu Normal University Qufu 273165 PRC School of Electrical Engineering ＆ Automation Xuzhou Normal University Xuzhou 221116 PRC

This paper considers a concrete stochastic nonlinear system with stochastic unmeasurable inverse dynamics. Motivated by the concept of integral input-to-state stability （iISS） in deterministic systems and stochastic input-to-state stability （SISS） in stochastic systems, a concept of stochastic integral input-to-state stability （SiISS） using Lyapunov functions is first introduced. A constructive strategy is proposed to design a dynamic output feedback control law, which drives the state to the origin almost surely while keeping all other closed-loop signals almost surely bounded. At last, a simulation is given to verify the effectiveness of the control law.

关键词： Output feedback stochastic input-to-state stability (SISS) stochastic integral input-to-state stability (SilSS) stochastic inverse dynamic stochastic nonlinear systems.

Research on the Low-carbon Cementitious Materials:Effect of Triisopropanolamine on the Hydration of Phosphorous Slag and Steel Slag

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Journal of Wuhan University of Technology(Materials Science) 2023年第6期38卷 1348-1359页

作者： ZHANG Ting MA Baoguo xia yu State Key Laboratory of Silicate Materials for Architectures Wuhan University of TechnologyWuhan 430070China School of Surveying&Testing Shaanxi Railway InstituteWeinan 714000China

Cement,phosphorous slag(PS),and steel slag(SS)were used to prepare low-carbon cementitious materials,and triisopropanolamine(TIPA)was used to improve the mechanical properties by controlling the hydration *** experimental results show that,by using 0.06%TIPA,the compressive strength of cement containing 60%PS or 60%SS could be enhanced by 12%or 18%at 28 *** presence of TIPA significantly affected the hydration process of PS and SS in *** the early stage,TIPA accelerated the dissolution of Al in PS,and the formation of carboaluminate hydrate was facilitated,which could induce the hydration;TIPA promoted the dissolution of Fe in SS,and the formation of Fe-monocarbonate,which was precipitated on the surface of SS,resulting in the postponement of hydration,especially for the high SS *** the later stage,under the continuous solubilization effect of TIPA,the hydration of PS and SS could refine the pore *** was noted that compared with portland cement,the carbon emissions of cement-PS-TIPA and cement-SS-TIPA was reduced by 52%and 49%,respectively.

关键词： phosphorous slag steel slag high content trisopropanolamine hydration process lowcarbon emissions