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Liu M.,Dalian University of Technology | Shen Z.,Dalian University of Technology | Guo X.,Dalian University of Technology | Song C.,Dalian University of Technology | Song C.,Pennyslvania State University
Huagong Xuebao/CIESC Journal | Year: 2015

Isopropylation of 4-isopropybiphenyl to 4, 4'-diisopropylbiphenyl was carried out over hierarchical mesoporousmordenite zeolites through alkalis modification of H-mordenite zeolite in a fixed-bed reactor. In order to investigate the effects of the pore structure and the acid sites of the zeolite samples on the catalytic properties, the parent and modified zeolite samples were thoroughly characterized with X-ray diffraction (XRD), transmission electron microscopy (TEM), ammonia temperature programmed desorption (NH3-TPD), and N2 physical adsorption-desorption. The results showed that the alkalis treatment adapted the pore structure, and the acid strength and amount without obvious destruction to the MOR topological structure. This adaption was contributed to the improvements of 4-isopropybiphenyl conversion and reaction stability. Modifying the sample with alkalis first and then followed by an acid treatment was in favor of removing the extra-framework alumina from the alkalis treatment and adapting the acid sites on the extra surface of the sample, which can successfully improve the selectivity of 4, 4'-diisopropylbiphenyl. © All right reserved. Source


Lu Y.,Pennyslvania State University | Luo X.,University of New Mexico | Polgar M.,Pennyslvania State University | Cao Y.,Xian Jiaotong University
Journal of Computer Information Systems | Year: 2010

Computer crime hackers have been identified as a primary threat to computer systems, users, and organizations. Much extant research on hackers is conducted from a technical perspective and at an individual level of analysis. This research empirically examines the social organization of a hacker community by analyzing one network called Shadowcrew. The social network structure of this infamous hacker group is established using social networking methods for text mining and network analysis. Analysis of relationships among hackers shows a decentralized network structure. Leaders are identified using four actor centrality measures (degree, betweenness, closeness, and eigenvector) and found to be more involved in thirteen smaller sub-groups. Based on our social network analysis, Shadowcrew exhibits the characteristics of deviant team organization structure. Source


Weichel R.,Pennyslvania State University | Wang G.,Aura Systems | Mayer J.,Pennyslvania State University | Hofmann H.,University of Michigan
2010 IEEE Energy Conversion Congress and Exposition, ECCE 2010 - Proceedings | Year: 2010

LC filters at the input of a DC-DC converter can introduce instability when used with feedback control. Traditional methods of addressing this issue focus on sizing the input filter to avoid instability, introducing passive damping elements, and, most recently, using state feedback to actively stabilize the input filter. This work presents a new method of actively stabilizing the input filter via current-mode control, using a control law that incorporates an additional feedback term for the input capacitor voltage. The stability of a buck converter under such a control law is investigated via root locus, and analysis is verified by experimental results. © 2010 IEEE. Source


Reed P.M.,Pennyslvania State University | Kasprzyk J.R.,Pennyslvania State University | Kirsch B.R.,University of North Carolina at Chapel Hill | Characklis G.W.,University of North Carolina at Chapel Hill
Modelling for Environment's Sake: Proceedings of the 5th Biennial Conference of the International Environmental Modelling and Software Society, iEMSs 2010 | Year: 2010

There is a growing consensus that non-structural supply management instruments such as water markets have significant potential to reduce the risks and vulnerabilities in complex urban water systems. This paper asks a common question, "What are the tradeoffs for a city using water market supply instruments?". This question emerges quickly in policy and management, but we contend its answer is deceptively difficult to attain using traditional planning tools and management frameworks. This paper demonstrates these issues using visualization and many-objective planning tools demonstrated in the context of a city in the Lower Rio Grande Valley (LRGV) of Texas, USA determining how to use its regional water market to manage population and drought risks. Source


Rozic B.,Jozef Stefan Institute | Malic B.,Jozef Stefan Institute | Malic B.,Jozef Stefan International Postgraduate School | Ursic H.,Jozef Stefan Institute | And 7 more authors.
Ferroelectrics | Year: 2012

The electrocaloric effect (ECE) has recently become very attractive phenomenon due to its various potential applications, for example in heating or cooling devices of new generation which could be more efficient and environmentally friendly. Here a direct measurements of the ECE in thick films of 8/65/35 PLZT ceramics, and in the relaxor ferroelectric polymer composition P(VDF-TrFE-CFE) 0.95-P(VDF-CTFE) 0.05 near room temperature are presented. Our results are consistent with those obtained by indirect measurements. The maximum of the ECE responsivity ΔT EC/E in 8/65/35 PLZT thick films is achieved near the critical point, and in the terpolymer/copolymer blends it is shifted toward higher fields. Source

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