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RISS 인기검색어
- 검색키워드
- 저자 : Songhua Ma (검색결과 3 건)
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Songhua Ma,Zhaoliang Jiang,Wenping Liu 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.6 No.2
By taking energy awareness and efficiency into consideration, this research applies multiple linear regression (MLR) models and artificial neural networks (ANNs) for predicting the real-time heating energy demand and natural gas consumption in the drying chamber of an automotive painting line. With the estimation of the correlation and randomness during the painting process, a total of six fundamental variables that integrate energy, product and process data are considered in order to cover the impact factors of the natural gas consumption. The independent variable value, used to calibrate and evaluate the model, is obtained from our constructed energy consumption monitoring system. In the prediction cases, the ANN-based model, which offers a well performance, provides great precision in the determination of the natural gas demand with an R2 coefficient and other error measurements of over 90%. Based on the MLR model, the process temperature and the corresponding variation are found to be two decisive factors for the natural gas consumption. It is foreseen that the ANN model, which can effectively perform input/output mapping, is reliable and powerful for predicting the natural gas consumption and estimating the energy demand. Being a general data-driven method, our method is convenient for application to other heating process lines and even other energy-consuming plants.
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Songhua Ma,Tianliang Hu,Zhenqi Xiong 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.22 No.6
Tolerance analysis methods, which are important to achieve a balance between manufacturing costs and functional requirements, have been studied and improved over the last 30 years. This paper proposes a new method to improve the precision of assembly simulation for statistical assembly simulation; by investigating the effect of the geometric deviations and mechanical behaviors of assembly contact on the stack-up assembly deviation by combining the recent theories on the tolerance analysis of rigid bodies and local contact deformation. To improve the precision of the tolerance analysis, real parts with form defects were simulated with the help of non-nominal skin model shapes. The SMSs were first considered to be rigid, and a quadratic optimization-based method for the rigid body displacement was used to calculate the initial contact points of all the SMSs. Next, contact deformation, following Hertzian contact theory, occurred at the initial contact points, which changed the relative positions of the SMSs in the subsequent interactions. The iteration process was convergent, and the final simulation for tolerance analysis could be generated after several iterations. Case studies demonstrated the practicality of the proposed method. Their actual assembly deviations were simulated by combining the effects of geometric deviations and local surface deformations. Since the proposed tolerance analysis framework based on statistical assembly simulation, it is expected to control the functional requirements of mechanical assemblies with much rough tolerance design and help optimize the tolerance in the future.
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Hua Ye,Hongyu Wu,Liangyuan Chen,Songhua Ma,Kaifeng Zhou,Guobing Yan,Jiazhong Shen,Dongcheng Chen,Shi‑Jian Su 대한금속·재료학회 2018 ELECTRONIC MATERIALS LETTERS Vol.14 No.2
A series of new small molecules based on symmetric electron-acceptor of 1,3,4-oxadiazole moiety or its asymmetric isomerof 1,2,4-oxadiazole unit were successfully synthesized and applied to solution-processable blue phosphorescent organic lightemittingdiodes for the first time, and their thermal, photophysical, electrochemical properties and density functional theorycalculations were studied thoroughly. Due to the high triplet energy levels (ET, 2.82–2.85 eV), the energy from phosphorescentemitter of iridium(III) bis[(4,6-difluorophenyl)-pyridinate-N,C2′]picolinate (FIrpic) transfer to the host molecules couldbe effectively suppressed and thus assuring the emission of devices was all from FIrpic. In comparison with the para-modeconjugation in substitution of five-membered 1,3,4-oxadiazole in 134OXD, the meta-linkages of 1,2,4-isomer appending withtwo phenyl rings cause the worse conjugation degree and the electron delocalization as well as the lower electron-withdrawingability for the other 1,2,4-oxadiazole-based materials. Noting that the solution-processed device based on 134OXD containing1,3,4-oxadiazole units without extra vacuum thermal-deposited hole/exciton-blocking layer and electron-transportinglayer showed the highest maximum current efficiency (CEmax) of 8.75 cd/A due to the excellent charge transporting ability of134OXD, which far surpassed the similar devices based on other host materials containing 1,2,4-oxadiazole units. Moreover,the device based on 134OXD presented small efficiency roll-off with current efficiency (CE) of 6.26 cd/A at high brightnessup to 100 cd/m2. This work demonstrates different nitrogen and oxygen atom orientations of the oxadiazole-based hostmaterials produce major impact on the optoelectronic characteristics of the solution-processable devices.
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