Mn Heterogeneity and Ductility Improvement Realized by Slow Heating Mn-Partitioned Pearlit

Dezhen Yang,Jiusan Xiao,Chao Zhang,Yingchun Wang,Zhiping Xiong 대한금속·재료학회 2024 METALS AND MATERIALS International Vol.30 No.2

The Mn heterogeneity in the medium manganese steel has been realized deliberately using fast heating. However, fast heatingis not easy for industrial production. Here, we counter-intuitively demonstrate that the slow heating not only can retain theMn-heterogeneous distribution from alternative Mn-enriched cementite and Mn-depleted ferrite in the initial pearlite, butalso modify the stability, morphology and fraction of retained austenite (RA). Compared to fast heating, a wider distributionand a lower average content of Mn in film RA are achieved due to the transition of austenite formation from partition localequilibrium to negligible partition local equilibrium. Meanwhile, the slow heating boosts the dissolution of the sphericalcementite, leading to a stronger retention of spherical RA. Consequently, slow heating exhibits a 30% larger ductility owingto a stronger austenite-to-martensite transformation during straining while the strength keeps similar. The present studyindicates that the slow heating opens a new avenue to produce Mn-heterogeneous steels having high strength and ductility.

Surface modification of recycled carbon fiber and its reinforcement effect on nylon 6 composites: Mechanical properties, morphology and crystallization behaviors

Nan Feng,Xiaodong Wang,Dezhen Wu 한국물리학회 2013 Current Applied Physics Vol.13 No.9

Recycled carbon fiber (RCF) was employed as a reinforcement material for preparation of nylon 6-basedthermoplastic composites. An effective approach was developed to clean and modify the surface conditionof RCF with nitric acid and then with an epoxy macromolecular coupling agent. The interfacialadhesion between RCF and nylon 6 matrix was improved significantly as a result of such a surfacemodification. Consequently, the reinforcing potential of the RCF was enhanced substantially, and thus,the mechanical properties and thermal stabilities of nylon 6 composites were improved remarkably. Themorphologies of fracture surfaces indicated that RCF achieved a homogeneous dispersion in nylon 6matrix due to good interfacial boding between fibers and matrix. The studies of non-isothermal andisothermal crystallization behaviors showed that RCF acted as a nucleation agent for the crystallization ofnylon 6; therefore, the crystallization rate and nucleation density increased notably due to the heterogeneousnucleating effect of RCF in the matrix. These crystallization features may be advantageous forthe enhancement of mechanical performance and processability of nylon 6-based composites. This studymay provide a design guide for RCF-reinforced nylon 6 composites with a great potential as well as a lowcost for industrial and civil applications.

Monitoring Failure Behaviour of Pultruded CFRP Composites by Electrical Resistance Measurement

Yaqin Mao,Yunhua Yu,Dezhen Wu,Xiaoping Yang 한국탄소학회 2004 Carbon Letters Vol.5 No.1

The failure behaviours of unidirectional pultruded carbon fiber reinforced polymer (CFRP) composites were monitored by the electrical resistance measurement during tensile loading, three-point-bending, interlaminar shear loading. The tensile failure behaviour of carbon fiber tows was also investigated by the electrical resistance measurement. Infrared thermography non-destructive evaluation was performed in real time during tensile test of CFRP composites to validate the change of microdamage in the materials. Experiment results demonstrated that the CFRP composites and carbon fiber tows were damaged by different damage mechinsms during tensile loading, for the CFRP composites, mainly being in the forms of matrix damage and the debonding between matrix and fibers, while for the carbon fiber tows, mainly being in the forms of fiber fracture. The correlation between the infrared thermographs and the change in the electrical resistance could be regarded as an evidence of the damage mechanisms of the CFRP composites. During three-point-bending loading, the main damage forms were the simultaneity fracture of matrix and fibers firstly, then matrix cracking and the debonding between matrix and fiber were carried out. This results can be shown in Fig. 9(a) and (b). During interlaminar shear loading, the change in the electrical resistance was related to the damage degree of interlaminar structure. Electrical resistance measurement was more sensitive to the damage behaviour of the CFRP composites than the stress/time curve.

Finite-time Fault Detection Filtering for Switched Singular Systems with All Modes Unstable: an ADT Approach

Qingyu Su,Zhongxin Fan,Dezhen Zhang,Jian Li 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.8

This paper finishes the fault detection (FD) problem for switched singular systems with all subsystems unstable. Considering the particularity of singular systems, the regularity and impulse-free property analysis on it are carried out. Utilizing a time-driven switching strategy, a switching signal is proposed and the finite-time stability is guaranteed firstly. Then, with the help of discretized Lyapunov function, a piecewise Lyapunov function is employed to accomplish the finite-time boundedness with L2-gain analysis. Through transferring the fault detection filters design into the L2-gain analysis, we can obtain the existence conditions of the FD detector via linear matrices inequalities (LMIs). Finally, the effectiveness and validity are illustrated by two examples.

Damping and transformation behaviors of Ti50(Pd50−xCrx) shape memory alloys with x ranging from 4.0 to 5.0

Deqing Xue,Ruihao Yuan,Dezhen Xue,Yumei Zhou,Guojun Zhang,Xiangdong Ding,Jun Sun 한국물리학회 2018 Current Applied Physics Vol.18 No.7

The damping and transformation behaviors of Ti50(Pd50−xCrx) shape memory alloys with x ranging from 4.0 to 5.0 are systematically investigated. The damping capacity (Q−1) at the martensitic transformation is found to be inversely proportional to the square root of frequency, i.e., Q−1∝ω−0.5. A relaxation peak or shoulder is observed slightly below the martensitic transformation damping peak for compositions within the compositional crossover region (4.5 ⩽x⩽ 4.8). Furthermore, the damping capacity at the martensitic transformation is smaller within the compositional crossover region (4.5 ⩽x⩽ 4.8), compared with that of compositions at both sides (x = 4.0 and x = 5.0). These observations can be ascribed to the hysteretic motion of interfaces between different phases near the compositional crossover region.

Monitoring Failure Behaviour of Pultruded CFER Composites by Electrical Resistance Measurement

Yaqin Mao,Yunhua Yu,Dezhen Wu,Xoaping Yang 한국탄소학회 2004 Carbon Letters Vol.5 No.1

LANDFILLING OF WASTE INCINERATION RESIDUES: TOWARDS NEW APPROACHES

( Thomas H. Christensen ),( Thomas Astrup ),( Zuansi Cai ),( Dezhen Chen ) 한국폐기물자원순환학회 2002 APLAS Vol.2002 No.1

Residues from waste incineration are bottom ashes and air-pollution-control (APC) residues including fly ashes. The leaching of heavy metals and salts from the ashes is substantial and a wide spectrum of leaching tests and corresponding criteria have been introduced to regulate the landfilling of the ashes. Leaching test, however, must be selected carefully to provide information relevant for the actual disposal scenario and for evaluating the benefits of pre-treating the residues prior to landfilling. This paper describes research at the Technical University of Denmark addressing some of these issues focusing on pH-development in landfilled residues, effects of leaching test conditions on Cr leaching and effects of pre-treatment with FeSO₄.

Antagonism of tomato spotted wilt virus against tomato yellow leaf curl virus in Nicotiana benthamiana detected by transcriptome analysis

Qiao Ning,Liu Yongguang,Liu Jie,Zhang Dezhen,Chi Wenjuan,Li Jintang,Zhu Xiaoping,Liu Hongmei,Li Fajun 한국유전학회 2023 Genes & Genomics Vol.45 No.1

Background Tomato spot wilt virus (TSWV) and tomato yellow leaf curl virus (TYLCV) are highly harmful viruses in agricultural production, which can cause serious economic losses to crops and even devastating consequences for vegetable yield in some countries and regions. Although the two viruses belong to different families and have different transmission vectors, they share most hosts. Objective This study aimed to examine the transcriptomic expression of single and mixed inoculations of TSWV and TYLCV, leading to antagonism using high-throughput RNA sequencing. Methods We confirmed the single and mixed infections of these viruses in Nicotiana benthamiana (N. benthamiana) by artificial inoculation. And the expression changes of related genes and their biological functions and pathways during the mixed infection of TSWV and TYLCV were analyzed by comparative transcriptome. Results Basically, similar symptoms were observed in the plants singly infected with TSWV and co-infected with TYLCV; the symptoms of TYLCV in the co-infected plants were not obvious compared with single TYLCV infections. When inoculated with TYLCV, the accumulation of the virus significantly reduced in single and mixed infections with TSWV; the TSWV accumulated slightly less in co-infection with TYLCV, whereas this reduction was much smaller than that of TYLCV. The results suggested that TSWV had an antagonistic effect on the accumulation of TYLCV in N. benthamiana. It mainly focused on the changes in unique differentially expressed genes (DEGs) caused by the co-infection of TSWV and TYLCV. The eight pathways enriched by upregulated DEGs mainly included amino acid biosynthesis, citrate cycle (or tricarboxylic acid cycle, TCA cycle), and so on. However, only pentose phosphate pathway (PPP) and peptidoglycan biosynthesis could be downregulated in the Kyoto Encyclopedia of Genes and Genomes pathway in which peptidoglycan biosynthesis was involved in upregulated and downregulated pathways. Conclusions The antagonistic effect of TSWV on TYLCV in N.benthamiana and the change trends and specific pathways of DEGs in this process were found. Our study provided new insights into the host regulation and competition between viruses in response to TSWV and TYLCV mixed infection.

폐기물 소각 잔류물의 매립 : 새로운 접근 방법에 대해

( Thomas H. Christensen ),( Thomas Astrup ),( Zuansi Cai ),( Dezhen Chen ) 한국폐기물자원순환학회 2002 APLAS Vol.2002 No.2

폐기물 소각시설로부터의 잔류물은 대표적으로 바닥재와 비산재를 포함한 대기오염방지시설에서 나오는 잔류물이다. 이러한 재로부터 상당량의 중금속과 염이 용출되며, 다양한 용출실험을 통하여 비산재 및 바닥재의 매립 규제를 위한 기준이 제안 되어왔다. 그러나 실제 처분하는 현장과 동일하게 정보를 제공 및 매립하기 전에 잔류물들의 전처리의 이익평가를 하기 위해서 용출실험은 주의 깊게 선택 되어야만 한다. 본 논문은 매립된 잔류물에서의 pH-변화 및 Cr 용출능에 대한 용출실험의 영향과 FeSO₄ 를 이용한 전처리의 효과를 서술하였다. Residues from waste incineration are bottom ashes and air-pollution-control (APC) residues including fly ashes. The leaching of heavy metals and salts from the ashes is substantial and a wide spectrum of leaching tests and corresponding criteria have been introduced to regulate the landfilling of the ashes. Leaching test, however, must be selected carefully to provide information relevant for the actual disposal scenario and for evaluating the benefits of pre-treating the residues prior to landfilling. This paper describes research at the Technical University of Denmark addressing some of these issues focusing on pH-development in landfilled residues, effects of leaching test conditions on Cr leaching and effects of pre-treatment with FeSO₄.

NOx removal by non-thermal plasma at low temperatures with amino groups additives

Zhenzhen Guan,Jian-Xing Ren,Dezhen Chen,Liu Hong,Fangqin Li,Du Wang,Yuanhuang Ouyang,Yang Gao 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.11

NOx removal from flue gas using direct current (DC) narrow pulsed discharge-induced non-thermal plasma (NTP) was experimentally investigated. Factors such as additives, NOx initial concentrations, residence time, reaction temperatures inside the NTP reactor, and so on were investigated to evaluate their effects on NOx removal efficiencies. The focus was on the effects of additives containing amino groups. The results showed that H2O addition enhanced NOx removal, NH3 could further increase the NOx removal efficiencies under the same conditions without an obvious NH3 slip, and N2H4 was the most effective additive by reducing NOx to N2. X-Ray diffraction (XRD) analysis of the products collected from the NTP reactor demonstrated that NOx removal inside the NTP reactor was mainly based on NOx oxidation when ammonia or H2O was used as an additive, while NOx removal was mainly based on NOx reduction with the N2H4 additive.