Intrinsic kinetics of one-step dimethyl ether synthesis from hydrogen-rich synthesis gas over bi-functional catalyst

Chengyuan Cheng,Weiyong Ying,Haitao Zhang,Dingye Fang 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.7

The reaction kinetics of the dimethyl ether synthesis from hydrogen-rich synthesis gas over bi-functional catalyst was investigated using an isothermal integral reactor at 220-260 oC temperature, 3-7MPa pressure, and 1,000-2,500 mL/g·h space velocity. The H_2/CO ratio of the synthetic gas was chosen between 3 : 1 and 6 : 1. The bi-functional catalyst was prepared by physically mixing commercial CuO/ZnO/Al_2O_3 and γ-alumina, which act as methanol synthesis catalyst and dehydration catalyst, respectively. The three reactions, including methanol synthesis from CO and CO_2as well as methanol dehydration, were chosen as independent reactions. The Langmuir-Hinshelwood kinetic models for dimethyl ether synthesis were adopted. Kinetics parameters were obtained using the Levenberg-Marquardt mathematical method. The model was reliable according to statistical and residual error analyses. The effects of different process conditions on the reactor performance were also investigated.

Analytical modeling of axial stiffness of tensile bolted joints under concentric external load

Peng He,Jiaxin Liu,Chengyuan Zhang,Zhansheng Liu 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.11

Stiffness of bolted joints is a critical parameter for determining deformations and natural frequencies of assemblies. In this study, the effect of external load on axial stiffness of bolted joints is clarified theoretically for the first time. The stiffness of stress zones between and beyond load planes is derived on the basis of the strain energy method and used to formulate the stiffness of bolted joints. The influence of the distance between the load planes of the external load, axial positions of the external load, and difference in the material of the clamped parts on the stiffness of the bolted joints are investigated by applying the proposed formulations and finite element method. Comparisons with finite element results indicate that the proposed formulation can accurately predict the stiffness of the bolted joints.

SSF: Sentence Similar Function Based on word2vector Similar Elements

Yuan, Xinpan,Wang, Songlin,Wan, Lanjun,Zhang, Chengyuan Korea Information Processing Society 2019 Journal of information processing systems Vol.15 No.6

In this paper, to improve the accuracy of long sentence similarity calculation, we proposed a sentence similarity calculation method based on a system similarity function. The algorithm uses word2vector as the system elements to calculate the sentence similarity. The higher accuracy of our algorithm is derived from two characteristics: one is the negative effect of penalty item, and the other is that sentence similar function (SSF) based on word2vector similar elements doesn't satisfy the exchange rule. In later studies, we found the time complexity of our algorithm depends on the process of calculating similar elements, so we build an index of potentially similar elements when training the word vector process. Finally, the experimental results show that our algorithm has higher accuracy than the word mover's distance (WMD), and has the least query time of three calculation methods of SSF.

Comprehensive Evaluation of Impacts of Connecting Distributed Generation to the Distribution Network

Jin, Wei,Shi, Xuemei,Ge, Fei,Zhang, Wei,Wu, Hongbin,Zhong, Chengyuan The Korean Institute of Electrical Engineers 2017 Journal of Electrical Engineering & Technology Vol.12 No.2

In this paper, we study the various impacts of connecting distributed generation (DG) to the distribution network. The comprehensive evaluation index system (CEIS) of four hierarchies is established, considering economy, reliability and voltage quality, and the calculation methods of different indexes are presented. This paper puts forward an improved triangular fuzzy number analytic hierarchy process (ITFNAHP) to weight the second level indexes (SLI) and the third level indexes (TLI), and calculates the variation coefficient to weight the fourth level indexes (FLI). We calculate the comprehensive weight coefficients based on the weight coefficients of the SLI, TLI and FLI, and then calculate the comprehensive evaluation of satisfaction (CES) of different access schemes. On the basis of the IEEE 33-bus example system, simulations of the calculation methods and the comprehensive evaluation method are carried out under different DG access schemes according to the same total investment cost and the same permeability, respectively, and the simulation results are analyzed and discussed.

Comprehensive Evaluation of Impacts of Connecting Distributed Generation to the Distribution Network

Wei Jin,Xuemei Shi,Fei Ge,Wei Zhang,Hongbin Wu,Chengyuan Zhong 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.2

In this paper, we study the various impacts of connecting distributed generation (DG) to the distribution network. The comprehensive evaluation index system (CEIS) of four hierarchies is established, considering economy, reliability and voltage quality, and the calculation methods of different indexes are presented. This paper puts forward an improved triangular fuzzy number analytic hierarchy process (ITFNAHP) to weight the second level indexes (SLI) and the third level indexes (TLI), and calculates the variation coefficient to weight the fourth level indexes (FLI). We calculate the comprehensive weight coefficients based on the weight coefficients of the SLI, TLI and FLI, and then calculate the comprehensive evaluation of satisfaction (CES) of different access schemes. On the basis of the IEEE 33-bus example system, simulations of the calculation methods and the comprehensive evaluation method are carried out under different DG access schemes according to the same total investment cost and the same permeability, respectively, and the simulation results are analyzed and discussed.

Synonymy of soil-feeding termites Pseudocapritermes sowerbyi and Pseudocapritermes largus, with evidence from morphology and genetics

Xuan Ruoyue,Dai Qingfeng,He Can,Zhang Dayu,Pan Chengyuan 한국응용곤충학회 2021 Journal of Asia-Pacific Entomology Vol.24 No.1

Pseudocapritermes Kemner is a termite group that constructs subterranean gallery systems in topsoil. This genus is distributed in the Oriental region and contains 18 species. Dependence on the morphological measurements of soldiers makes the taxonomy of Pseudocapritermes difficult. In this study, we compared morphological characters of soldiers and adults of P. largus and P. sowerbyi. In addition, three fulllength mitochondrial genes (COI, COII, and 16S rRNA) were sequenced from a total of eight P. largus and P. sowerbyi colonies. Morphological comparison of soldiers showed that P. largus is larger than P. sowerbyi, but there was overlap in some measurements. In adults, the morphological characters of P. largus were congruent with those of P. sowerbyi. Sequence alignments of COI, COII, and 16S rRNA revealed a high pairwise genetic identity (ranging from 99.64 to 100%) between the two species, which suggested that P. largus and P. sowerbyi are the same species. Molecular phylogenetic analysis based on COII revealed that Pseudocapritermes belongs to the Termes group having soldiers with asymmetrical snapping mandibles and is more closely related to Sinocapritermes than to other Termes group genera distributed in China. Morphological similarity and genetic identity indicate that P. largus is a junior synonym of P. sowerbyi.

SSF: Sentence Similar Function Based on word2vector Similar Elements

Xinpan Yuan,Songlin Wang,Lanjun Wan,Chengyuan Zhang 한국정보처리학회 2019 Journal of information processing systems Vol.15 No.6

In this paper, to improve the accuracy of long sentence similarity calculation, we proposed a sentence similaritycalculation method based on a system similarity function. The algorithm uses word2vector as the systemelements to calculate the sentence similarity. The higher accuracy of our algorithm is derived from twocharacteristics: one is the negative effect of penalty item, and the other is that sentence similar function (SSF)based on word2vector similar elements doesn’t satisfy the exchange rule. In later studies, we found the timecomplexity of our algorithm depends on the process of calculating similar elements, so we build an index ofpotentially similar elements when training the word vector process. Finally, the experimental results show thatour algorithm has higher accuracy than the word mover’s distance (WMD), and has the least query time ofthree calculation methods of SSF.