The kinetics of CO2 reforming of methane has been studied at 976－1033K on a commercial NiO/CaO/Al2O3 catalyst in a packed-bed continuous reactor. The reaction was carried out at atmospheric pressure and CO2/CH4 ratio...The kinetics of CO2 reforming of methane has been studied at 976－1033K on a commercial NiO/CaO/Al2O3 catalyst in a packed-bed continuous reactor. The reaction was carried out at atmospheric pressure and CO2/CH4 ratio ＞ 2. The Hougen-Watson rate models were fitted to experimental data assuming the disso ciative adsorption of methane as the rate-determining step. The reaction rate showed an effective reaction order of about unity for CH4. The apparent activity energy was found to be 104 kJ·mol-1. Therefore the kinetic reaction parameters were determined and a possible reaction mechanism was proposed.展开更多
In this work, property clustering techniques and group contribution methods are combined to enable simultaneous consideration of process performance requirements and molecular property constraints. Using this methodol...In this work, property clustering techniques and group contribution methods are combined to enable simultaneous consideration of process performance requirements and molecular property constraints. Using this methodology, the process design problem is solved to identify the property targets corresponding to the desired process performance. A significant advantage of the developed methodology is that for problems that can be satisfactorily described by only three properties, the process and molecular design problems can be simultaneously solved visually on a ternary diagram, irrespective of how many molecular fragments are included in the search space. On the ternary cluster diagram, the target properties are represented as individual points if given as discrete values or as a region if given as intervals. The structure and identity of candidate components is then identified by combining or ＂mixing＂ molecular fragments until the resulting properties match the targets.展开更多
Hazardous gas detection systems play an important role in preventing catastrophic gas-related accidents in process industries. Even though effective detection technology currently exists for hazardous gas releases and...Hazardous gas detection systems play an important role in preventing catastrophic gas-related accidents in process industries. Even though effective detection technology currently exists for hazardous gas releases and a majority of process installations have a large number of sensitive detectors in place, the actual operating performance of gas detection systems still does not meet the expected requirements. In this paper, a riskbased methodology is proposed to optimize the placement of hazardous gas detectors. The methodology includes three main steps, namely, the establishment of representative leak scenarios, computational fluid dynamics(CFD)-based gas dispersion modeling, and the establishment of an optimized solution. Based on the combination of gas leak probability and joint distribution probability of wind velocity and wind direction, a quantitative filtering approach is presented to select representative leak scenarios from all potential scenarios. The commercial code ANSYS-FLUENT is used to estimate the consequence of hazardous gas dispersions under various leak and environmental conditions. A stochastic mixed-integer linear programming formulation with the objective of minimizing the total leak risk across all representative leak scenarios is proposed, and the greedy dropping heuristic algorithm(GDHA) is used to solve the optimization model. Finally, a practical application of the methodology is performed to validate its effectiveness for the optimal design of a gas detector system in a high-sulfur natural gas purification plant in Chongqing, China. The results show that an appropriate number of gas detectors with optimal cost-effectiveness can be obtained, and the total leak risk across all potential scenarios can be substantially reduced. This methodology provides an effective approach to guide the optimal placement of pointtype gas detection systems involved with either single or mixed gas releases.展开更多
the political socialization of college students is the purpose of the individual to accept political culture in the historical, social, cultural and the specific interaction, formation of political attitude, the pract...the political socialization of college students is the purpose of the individual to accept political culture in the historical, social, cultural and the specific interaction, formation of political attitude, the practice process of shaping the political people. Our country is in the period of social transition, this period of transformation of political, economic and cultural construction of the China different from traditional political culture atmosphere, in the impact of the global political factors, college students＇ political psychology, political attitude and political behavior has undergone a series of changes. These changes impact on the existing college students＇ political socialization outcomes, so that students show the political and social highlights issues in the process of social transformation. In this case,we should only study the college students＇ optimization approach of political socialization carefully, improve the level of Chinese college students＇ political socialization, to ensure China＇ s social transition in a stable order smoothly, develop socialist political requirements of qualified university students, so as to make the socialism prosperous.展开更多
Based on an integrated refining/chemical plant processing 15 Mt/a of crude and manufacturing 1.0 Mt/a of ethylene under the guideline of＂engaging in refining, olefins and aromatics by whatever appropriate means＂ to ...Based on an integrated refining/chemical plant processing 15 Mt/a of crude and manufacturing 1.0 Mt/a of ethylene under the guideline of＂engaging in refining, olefins and aromatics by whatever appropriate means＂ to maximize the overall value of the integrated refining/chemical plant, it is necessary to concentrate on working on the flow diagram and the solution for mutual supply of materials between the refinery and ethylene plant. After analyzing the feedstock slate, the composition and properties of products, it is proposed to optimize the integrated refming/chemical plant in order to reduce investment and operating cost to realize maximization of the value of the integrated plant.展开更多
Based on the study of supply chain(SC) and SC optimization in engineering projects, a mixed integer nonlinear programming(MINLP) optimization model is developed to minimize the total SC cost for international petroche...Based on the study of supply chain(SC) and SC optimization in engineering projects, a mixed integer nonlinear programming(MINLP) optimization model is developed to minimize the total SC cost for international petrochemical engineering projects. A steam cracking project is selected and analyzed, from which typical SC characteristics in international engineering projects in the area of petrochemical industry are summarized. The MINLP model is therefore developed and applied to projects with detailed data. The optimization results are analyzed and compared by the MINLP model, indicating that they are appropriate to SC management practice in engineering projects, and are consistent with the optimal priceeffective strategy in procurement. As a result, the model could provide useful guidance to SC optimization of international engineering projects in petrochemical industry, and improve SC management by selecting more reliable and qualified partner enterprises in SC for the project.展开更多
Since the late 1980s, the encounter between political economy and cultural studies within the field of media research has raised continuous debates and confrontations among academics and policymakers, but at the same ...Since the late 1980s, the encounter between political economy and cultural studies within the field of media research has raised continuous debates and confrontations among academics and policymakers, but at the same time it casts light on the important questions as well as methodology in media scholarship. This paper aims to analyze the differences between political economy and cultural studies, two primary but sometimes competing ways of examining media and communication, following a detailed description of their theoretical trajectory. Also, this paper suggests building a bridge connecting the two disciplines, the integration of which is essential to an adequate account of gender, race and social movement studies in addition to class analysis.展开更多
基金the Consejo Nacional de Investigacions Cientificas y Tecnicas (CONICET).
文摘The kinetics of CO2 reforming of methane has been studied at 976－1033K on a commercial NiO/CaO/Al2O3 catalyst in a packed-bed continuous reactor. The reaction was carried out at atmospheric pressure and CO2/CH4 ratio ＞ 2. The Hougen-Watson rate models were fitted to experimental data assuming the disso ciative adsorption of methane as the rate-determining step. The reaction rate showed an effective reaction order of about unity for CH4. The apparent activity energy was found to be 104 kJ·mol-1. Therefore the kinetic reaction parameters were determined and a possible reaction mechanism was proposed.
基金the US NSF CAREER Program (CTS-0546925)in part through a travel grant (0647113)
文摘In this work, property clustering techniques and group contribution methods are combined to enable simultaneous consideration of process performance requirements and molecular property constraints. Using this methodology, the process design problem is solved to identify the property targets corresponding to the desired process performance. A significant advantage of the developed methodology is that for problems that can be satisfactorily described by only three properties, the process and molecular design problems can be simultaneously solved visually on a ternary diagram, irrespective of how many molecular fragments are included in the search space. On the ternary cluster diagram, the target properties are represented as individual points if given as discrete values or as a region if given as intervals. The structure and identity of candidate components is then identified by combining or ＂mixing＂ molecular fragments until the resulting properties match the targets.
基金Supported by the National Natural Science Foundation of China(51474184)the Natural Science Foundation of the State Administration of Work Safety in China(2012-387,Sichuan-0021-2016AQ)
文摘Hazardous gas detection systems play an important role in preventing catastrophic gas-related accidents in process industries. Even though effective detection technology currently exists for hazardous gas releases and a majority of process installations have a large number of sensitive detectors in place, the actual operating performance of gas detection systems still does not meet the expected requirements. In this paper, a riskbased methodology is proposed to optimize the placement of hazardous gas detectors. The methodology includes three main steps, namely, the establishment of representative leak scenarios, computational fluid dynamics(CFD)-based gas dispersion modeling, and the establishment of an optimized solution. Based on the combination of gas leak probability and joint distribution probability of wind velocity and wind direction, a quantitative filtering approach is presented to select representative leak scenarios from all potential scenarios. The commercial code ANSYS-FLUENT is used to estimate the consequence of hazardous gas dispersions under various leak and environmental conditions. A stochastic mixed-integer linear programming formulation with the objective of minimizing the total leak risk across all representative leak scenarios is proposed, and the greedy dropping heuristic algorithm(GDHA) is used to solve the optimization model. Finally, a practical application of the methodology is performed to validate its effectiveness for the optimal design of a gas detector system in a high-sulfur natural gas purification plant in Chongqing, China. The results show that an appropriate number of gas detectors with optimal cost-effectiveness can be obtained, and the total leak risk across all potential scenarios can be substantially reduced. This methodology provides an effective approach to guide the optimal placement of pointtype gas detection systems involved with either single or mixed gas releases.
文摘the political socialization of college students is the purpose of the individual to accept political culture in the historical, social, cultural and the specific interaction, formation of political attitude, the practice process of shaping the political people. Our country is in the period of social transition, this period of transformation of political, economic and cultural construction of the China different from traditional political culture atmosphere, in the impact of the global political factors, college students＇ political psychology, political attitude and political behavior has undergone a series of changes. These changes impact on the existing college students＇ political socialization outcomes, so that students show the political and social highlights issues in the process of social transformation. In this case,we should only study the college students＇ optimization approach of political socialization carefully, improve the level of Chinese college students＇ political socialization, to ensure China＇ s social transition in a stable order smoothly, develop socialist political requirements of qualified university students, so as to make the socialism prosperous.
文摘Based on an integrated refining/chemical plant processing 15 Mt/a of crude and manufacturing 1.0 Mt/a of ethylene under the guideline of＂engaging in refining, olefins and aromatics by whatever appropriate means＂ to maximize the overall value of the integrated refining/chemical plant, it is necessary to concentrate on working on the flow diagram and the solution for mutual supply of materials between the refinery and ethylene plant. After analyzing the feedstock slate, the composition and properties of products, it is proposed to optimize the integrated refming/chemical plant in order to reduce investment and operating cost to realize maximization of the value of the integrated plant.
文摘Based on the study of supply chain(SC) and SC optimization in engineering projects, a mixed integer nonlinear programming(MINLP) optimization model is developed to minimize the total SC cost for international petrochemical engineering projects. A steam cracking project is selected and analyzed, from which typical SC characteristics in international engineering projects in the area of petrochemical industry are summarized. The MINLP model is therefore developed and applied to projects with detailed data. The optimization results are analyzed and compared by the MINLP model, indicating that they are appropriate to SC management practice in engineering projects, and are consistent with the optimal priceeffective strategy in procurement. As a result, the model could provide useful guidance to SC optimization of international engineering projects in petrochemical industry, and improve SC management by selecting more reliable and qualified partner enterprises in SC for the project.
文摘Since the late 1980s, the encounter between political economy and cultural studies within the field of media research has raised continuous debates and confrontations among academics and policymakers, but at the same time it casts light on the important questions as well as methodology in media scholarship. This paper aims to analyze the differences between political economy and cultural studies, two primary but sometimes competing ways of examining media and communication, following a detailed description of their theoretical trajectory. Also, this paper suggests building a bridge connecting the two disciplines, the integration of which is essential to an adequate account of gender, race and social movement studies in addition to class analysis.
