Quantitative evaluation method for machining accuracy retention of CNC machine tools considering degenerate trajectory fluctuation

Cong Feng,Zhaojun Yang,Chuanhai Chen,Jinyan Guo,Hailong Tian,Fanning Meng 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.6

Accuracy retention is an important performance index of CNC machine tools. At present, research on the evaluation of machining accuracy retention of CNC machine tools mainly focuses on accuracy value of a fixed time point or different time periods, but studies on the fluctuation degree of degradation trajectory related to time change are limited. Extracting simple and effective degradation characteristics of machining accuracy and then evaluating machining accuracy retention considering fluctuation of degradation trajectory are necessary. The volume error model of CNC machine tools is established on the basis of multibody system theory in this study. Three-dimensional volume error vector is transformed into one-dimensional machining accuracy degradation by calculating offset distance between spatial error and origin points. Degradation data obtained via regular measurement and calculation are used to establish the complete degradation trajectory model of the CNC machine tools machining accuracy using radial basis function interpolation method according to the fluctuation degree of degradation trajectory, and concepts of average degradation rate and average degradation amount are defined. Lastly, examples showed that these two indicators can intuitively reflect fluctuation degree of machining accuracy degradation of CNC machine tools and effectively and quantitatively evaluate accuracy retention of CNC machine tools. The quantitative evaluation method of accuracy retention of CNC machine tools defined in this study considers the fluctuation degree of accuracy degradation trajectory. The quantitative evaluation index of accuracy retention demonstrates satisfactory engineering application because it can reflect not only the accuracy change of a single machine tool but also accurately compare the accuracy retention between different machine tools.

Research on Crossing Tunnels' Seismic Response Characteristics

Cong Liu,Li-min Peng,Ming-feng Lei,Yu-feng Li 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.11

A large-scale shaking table test system and corresponding numerical model are designed to study the seismic characteristics of crossing tunnels. The calculated results are in good agreement with experimental data, both the results suggest that: Loading the El-Centro seismic wave, the maximum acceleration in upper tunnel’s crossing center section is located in the crown, the maximum strain is located in the haunch; meanwhile, the maximum acceleration and strain in underpass tunnel’s cross center section are both located in the crown. Affected by the underpass tunnel, at the side wall bottom of the upper tunnel, tests data reveal that the crossing center’s maximum acceleration is reduced for 30.9% and the strain was enlarged 170% than the normal section. Affected by the upper tunnel, at the haunch of the underpass tunnel, tests data reveal the crossing center’s maximum acceleration is enlarged by 10.0% and the strain is 27.2% reduced than the normal section.

Influence of Spatial Distribution of Pores on NMR Transverse Relaxation Time in Pebbly Sandstone

Feng Wu,Yanping Xi,Qicheng Fan,Cong Yao,Linlin Cong,Fengsheng Zhang,Yan Kuang 한국자기학회 2019 Journal of Magnetics Vol.24 No.4

The relationship between transverse relaxation time (T₂) and pore size distribution is the basis of NMR applications for rocks. However, the equations for T₂ are not accurate enough in rocks with complicated pore structures. Taking pebbly sandstone from the northwestern Junggar Basin in China as an example, the aim of this study is to discover the spatial distribution of pores and its influence on T₂. Porosity, permeability, micro-images and T₂ distributions were acquired from rock samples, and pore structure parameters were obtained from binarized thin section images. The results show that as the grain size increases, the proportion of dissolution pores increases and the spatial distribution of pores changes from a random to a clustered pattern. The relaxation of a hydrogen atom takes longer and T₂ is higher in dissolution pores compared with those in intergranular pores. New equations for T₂ that consider the spatial distribution of pores are proposed.

중국 여자축구선수의 포지션에 따른 체력 특성 비교

풍총(Feng Cong),정연택(Jeong, Yeon-Taek) 한국코칭능력개발원 2021 코칭능력개발지 Vol.23 No.2

심리기술훈련에 따른 중국 여자축구선수의 경쟁상태불안, 기분상태 및 fMRI 활성화

풍총 ( Feng Cong ),최연재 ( Yeonjae Choi ),정연택 ( Yeontaek Jeong ) 사단법인 아시아문화학술원 2021 인문사회 21 Vol.12 No.4

본 연구는 심리기술훈련이 중국 여자축구선수들의 경쟁상태, 기분상태 및 기능적 자기공명영상에 미치는 영향을 규명하고자 하였다. 실험(12명) 및 통제(12명)집단으로 총 24명을 대상으로 공분산분석을 실시하였다. 분석 결과, 긴장, 우울, 분노, 피로, 혼동 및 총정서장애에서 유의한 차이를 보였다. 그리고 기능적 자기공명영상 분석에서도 두 집단은 유의한 차이를 나타내었다. 결론적으로 심리기술훈련은 경쟁상태, 기분상태 및 기능적 자기공명영상에 긍정적 영향을 미치는 것으로 나타났다. 이러한 연구 결과를 토대로 뇌 기능에 대한 이해를 도모할 수 있었지만, 운동과 뇌의 변화에 대한 연구는 부족하기에 임상적으로 적용하기에는 어려운 실정이다. 이와 같은 의미에서 의학과 운동학적 접근의 통합성이 강조되어 임상데이터의 축척이 필요할 것으로 사료된다. The purpose of this study was to analyze the characteristics of female soccer players’ competitive anxiety, mood states, and functional magnetic resonance imaging (fMRI). 24 participants were assigned to one of two groups, experimental (n=12), control (n=12) in counter-balanced. The pre-test, post-test were administered to each group and the measures were the competitive state anxiety (CSAI-2), mood states (Poms), and the functional magnetic resonance imaging (fMRI). The data obtained from each measure were analyzed using ANCOVA and MATAB SPM. From the results, PST has a positive impact on the CSAI-2, POMS (negative emotions and TMD) and fMRI. Finally research direction for future PST with experience sports were discussed. Based on these research results, it was possible to understand the brain function, but it is difficult to apply it clinically due to the lack of research on movement and brain changes. In this sense, the integration of medical and kinematic approaches is emphasized and it is thought that the accumulation of clinical data is necessary.

Cyclic CO2 capture characteristics of a pellet derived from sol-gel CaO powder with Ca12Al14O33 support

Cong Luo,Ying Zheng,Yongqing Xu,Haoran Ding,Chuguang Zheng,Changlei Qin,Bo Feng 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.5

A novel calcium-based pellet was prepared by extrusion of sol-gel CaO powder and cement with high aluminum- based content. Limestone was used for comparison. The cyclic CO2 capture performance and carbonation kinetics of the sorbents were investigated in a thermogravimetric analyzer (TGA). The changes in phase and microstructure were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Brunauer Emmet Teller (BET) surface area, respectively. The results indicate that the pellet consisted of CaO and Ca12Al14O33 after initial calcination. Limestone reactivity decreased dramatically with the increase in the cycle number, whereas the pellet showed a relatively stable cyclic CO2 capture performance with high reactivity. The CO2 capture capacity of the pellet achieved 0.43 g CO2/g sorbent after 50 cycles at 650 oC and 850 oC for carbonation and calcination, respectively. Moreover, the pellet obtained fast carbonation rates with slight decay after multiple cycles. The porous microstructure of the pellet contributed to the high reactivity of the sorbent during high temperature reactions, and the support material of Ca12Al14O33, enhanced the cyclic durability of the calcium-based sorbents.

Effect of composite biological preservative containing Lactobacillus plantarum on postharvest litchi quality

Cong Xu,Wen-feng Hu,Shi Luo,Hua-jian Luo,Ke Ma,Yan-fang Li 한국식품과학회 2016 Food Science and Biotechnology Vol.25 No.6

Biological preservatives containing live microorganisms are environmentally friendly and non-toxic substances used to preserve the quality of fresh fruits. This study investigated whether a composite biological preservative containing live Lactobacillus plantarum (designated as DN003) could preserve the quality of postharvest litchi fruits at high temperature and in humid environment. Postharvest litchi fruits were briefly soaked in DN003, then dried and stored at 29–33oC with 95–98% relative humidity; prochloraz treatment was included as positive control and non-treatment as negative control. In comparison with negative control group, litchi fruits in both DN003-treated and positive control groups better retained their appearance with lower polyphenol oxidase and peroxidase activities and showed higher concentrations of vitamin C, titratable acids, and total sugar content. These data demonstrated that the new composite biological preservative containing L. plantarum is promising to be used in the preservation of postharvest litchi fruit, particularly in hightemperature and humid environment.

Running-in performance of 7075 aluminum alloy strengthened by burnishing technology

Cong Ding,Shiqing Feng,Zhizhao Qiao,Zhenyu Zhou,Zhongyu Piao 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.5

A 2D ultrasonic burnishing technology was employed to strengthen 7075 aluminum alloy. The running-in experiments for original and burnished samples were implemented, and the running-in performance was explored qualitatively and quantitatively. The results show that the worn surface of an original sample exhibited the peelings, scratches, and abrasive particles, yet the wear form of a burnished sample was relatively single, mainly with scratches. The quantitative parameter “maximum distance between phase points d max ” was calculated. During the friction and wear process, the d max of friction coefficient signal displayed the variation of first decreasing and then stabilizing, which was consistent with the running-in and steadystate stages of the friction system. Compared with the original sample, the burnished sample had a less d max , which indicated that the phase trajectory had a more convergence, and the friction system had a better stability. This study can guide surface strengthening and running-in performance analysis.

Molecular characterization and functional analysis of a protease-related protein in Chang-Liver cells

( Cong Rui Wang ),( Hui Yong Zhang ),( Hui Gen Feng ),( Bao Sheng Yang ),( Jogenananda Pramanik ),( Zhi Kun Guo ),( Jun Tang Lin ) 생화학분자생물학회 (구 한국생화학분자생물학회) 2010 BMB Reports Vol.43 No.5

In this study, the cDNA library of Chang-liver cells was immunoscreened using common ADAMs antibody to obtain ADAM related genes. We found one positive clone that was confirmed as a new gene by Blast, which is an uncharacterized helical and coil protein and processes protease activity, and named protease-related protein 1 (ARP1). The submitted GenBank accession number is AY078070. Molecular characterizations of ARP1 were analyzed with appropriate bioinformatics software. To analyse its expression and function, ARP1 was subcloned into glutathione S-transferase fusion plasmid pGEX-2T and expressed by E. coli system. The in vitro expression product of ARP1 was recognized by common ADAMs antibody with western blot. Interestingly, ARP1 cleaves gelatine at pH9.5, which suggests it is an alkaline protease. Semi-quantitative RT-PCR result indicates that ARP1 mRNA is strongly transcribed in the liver and the treated Chang-liver cells. [BMB reports 2010; 43(5): 375-381]

Preliminary Correlation Between Warm Needling Treatment for Knee Osteoarthritis of Deficiency-Cold Syndrome and Metabolic Functional Genes and Pathways

Conge Tan,Weijun Ding,Wenzhe Feng,Jianguo Wang,Miqu Wang 사단법인약침학회 2010 Journal of Acupuncture & Meridian Studies Vol.3 No.3

The warm needling technique used in traditional Chinese medicine has been shown to be effective in the treatment and prevention of knee osteoarthritis (OA), but the biological mechanisms behind this action have not been well explored. This study investigated the molecular mechanisms behind warm needling using cDNA microarray technology, thus providing further scientific evidence for its efficacy. Ten patients with knee OA of deficiency-cold syndrome were selected for 2 weeks of warm needling treatment. This treatment involved stimulating the selected acupoints using needles with a burning moxa stick on their handle for 40 minutes per session. Pain intensity and accumulated clinical scores of deficiency-cold syndrome were assessed pretreatment and posttreatment using a 40-factor questionnaire of OA with deficiency-cold syndrome. Four patients with the best therapeutic efficacy were selected for cDNA microarray testing. Among the four patients, 41, 246,57 and 70 differentially expressed genes were obtained, with more than 50% of these differentially expressed genes functionally linked to primary, cellular and energy metabolism pathways. This work demonstrates that the molecular mechanism behind warm needling treatment may be associated with the regulation of metabolism-related genes and pathways.