Gao H.,Northwestern University |
Hu J.,HUST |
Wilson C.,U. C. Santa Barbara |
Li Z.,Northwestern University |
And 2 more authors.
Proceedings of the ACM Conference on Computer and Communications Security | Year: 2010
Online social networks (OSNs) are exceptionally useful collaboration and communication tools for millions of users and their friends. Unfortunately, in the wrong hands, they are also extremely effective tools for executing spam campaigns and spreading malware. In this poster, we present an initial study to detect and quantitatively analyze the coordinated spam campaigns on online social networks in the wild. Our system detected about 200K malicious wall posts with embedded URLs, traced back to roughly 57K accounts. We find that more than 70% of all malicious wall posts are advertising phishing sites. Source
Lu L.,Huazhong University of Science and Technology |
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011
Walsh-Haar function system that was first introduced by us is a new kind of function systems, and has a good global / local property. This function system is called Walsh ordering function system since its generation kernel functions belong to Walsh ordering Walsh function system. We worked out a recursive property of the matrix WH KR m+1 corresponding to the first KR m+1 Walsh-Haar functions in Walsh-Haar function system, and proved that Walsh-Haar function system is perfect and orthogonal similar to Walsh function system and Haar function system. Thus, discrete Walsh-Haar transformation (DW-HT) is an orthogonal transformation that can be widely used in signal processing. In this paper, using the recursive property of the matrix WH KR m+1 and the fast algorithm of discrete Walsh transformation in Walsh ordering, we have designed a fast algorithm of Walsh ordering (k, k-1) type DW-HT based on the bisection technique. As one of its applications, we use it to detect image edges. Compare with some edge-detecting methods, the method in this paper detects more details of image edge. The idea and method used to design the fast algorithm in this paper can be used to design fast algorithms of other ordering (k, k-1) type DW-HTs and other discrete orthogonal transformations. © 2011 SPIE. Source
D'Ascenzo N.,Russian Academy of Sciences |
Marrocchesi P.S.,University of Siena |
Marrocchesi P.S.,National Institute of Nuclear Physics, Italy |
Moon C.S.,National Institute of Nuclear Physics, Italy |
And 7 more authors.
Journal of Instrumentation | Year: 2014
The development of an innovative position sensitive pixelated sensor to detect and measure with high precision the coordinates of the ionizing particles is proposed. The silicon avalanche pixel sensors (APiX) is based on the vertical integration of avalanche pixels connected in pairs and operated in coincidence in fully digital mode and with the processing electronics embedded on the chip. The APiX sensor addresses the need to minimize the material budget and related multiple scattering effects in tracking systems requiring a high spatial resolution in the presence of the large track occupancy. The expected operation of the new sensor features: low noise, low power consumption and suitable radiation tolerance. The APiX device provides on-chip digital information on the position of the coordinate of the impinging charged particle and can be seen as the building block of a modular system of pixelated arrays, implementing a sparsified readout. The technological challenges are the 3D integration of the device under CMOS processes and integration of processing electronics. © 2014 IOP Publishing Ltd and Sissa Medialab srl. Source
Lee M.-H.,National Yunlin University of Science and Technology |
Lee M.-H.,Hsiuping University of Science and Technology |
Chen J.-R.,Hsiuping University of Science and Technology |
Shiue G.-Y.,HUST |
And 2 more authors.
Journal of the Taiwan Institute of Chemical Engineers | Year: 2014
To explore the thermal runaway behavior of benzoyl peroxide (BPO) in industrial processes during upsets situations and to compare the difference of values between simulation and experimentation, two calorimeters, differential scanning calorimetry (DSC) and vent sizing package 2 (VSP2), were employed to measure thermokinetic data of the thermal decomposition of BPO, and to calculate values of parameters by simulation approach, which were based on kinetic models and the thermal safety software. This study shows the novel finding that benzoyl peroxide (BPO) has an autocatalytic reaction at low temperature. The simulation results showed that the Ea value was 124kJ/mol by VSP2 tests. The Ea value was much closer to Zaman's studies than the Ea values developed by the Kissinger and/or Ozawa methods. The Ea value resulting from the optimal fit approach average was 91.47±17.69kJ/mol also closer to Zaman's studies than values from the Kissinger and Ozawa methods. © 2013 Taiwan Institute of Chemical Engineers. Source
Tang G.,Huazhong University of Science and Technology |
Tang G.,Hubei Institute of Aerospace Chemotechnology |
Wen Y.,Huazhong University of Science and Technology |
Pang A.,Hubei Institute of Aerospace Chemotechnology |
And 7 more authors.
CrystEngComm | Year: 2014
Distinct from the common well faceted ZnO nanorods (R-ZnO), ZnO nanotetrapods (T-ZnO) exhibited a remarkable catalytic activity for the thermal decomposition of ammonium perchlorate (AP): the activation energy at high temperature decomposition (HTD) was significantly decreased to 111.9 kJ mol -1, much lower than 162.5 kJ mol-1 for pure AP and 156.9 kJ mol-1 for AP with R-ZnO. This was attributed to more abundant atomic steps on the surface of T-ZnO than that of R-ZnO, as evidenced by HRTEM and density function theory (DFT) calculations. It was shown that the initiation step of perchloric acid (PA) decomposition happened much faster on stepped T-ZnO edges, resulting in the formation of active oxygen atoms from HClO 4. The formed oxygen atoms would subsequently react with NH 3 to produce HNO, N2O and NO species, thus leading to an obvious decrease in the activation energy of AP decomposition. The proposed catalytic mechanism was further corroborated by the TG-IR spectroscopy results. Our work can provide atomic insights into the catalytic decomposition of AP on ZnO nanostructures. © 2014 The Royal Society of Chemistry. Source