Social network inference and privacy preserving trajectory publishing in mobile phone data

Mobile phone data are collected communication logs between human beings. There are two interesting aspects and applications of the data: finding social structures and mobility patterns. The data could not only offer insights about how people make friends with each other but also shed light on how people move around in cities. These questions could help potential applications in security control and smart city planning. One interesting problem in social networks is Social Network Inference problem. Given the original raw communication data, how to accurately infer the relevant social network from the raw data? Are there noisy actors to affect the legitimacy of the social network? We consider the noise removal process as an important issue in Social Network Inference process. In this work, the noise removal problem is formulated and studied. Effective noise removing techniques are proposed to tackle the problem. Another important application of the data is about the whereabouts of human beings. However, the privacy issue is prohibiting the sharing and study of the data. Recent study shows that more than 50% of the population in the United States could be uniquely identified if a similar mobile phone data as ours is published even with an anonymization on the IDs. We formulate the top location attack and prove that it is an NP-Complete problem to prevent such attack. Then, we propose our novel privacy preserving technique to modify the original data with minimal distortion

Experimental Studies on Interfacial Shear Characteristics between Polypropylene Woven Fabrics

Geotextile tubes are used in dam construction because fine tailings are difficult to use. The shear characteristics of geotextile tubes during dam operation are closely related to those of the materials used to construct the tubes. Pull-out tests can accurately reflect the interfacial shear characteristics between geosynthetics in practice, so pull-out tests were carried out for different interfacial types of polypropylene woven fabrics under dry and wet states. The effects of the type of interface and dry-wet states on the interfacial shear characteristics were investigated, and the impact mechanisms were also discussed. The results indicated that P-type interfaces (the warp yarn on the interface is parallel to the pulling direction) tended to harden. However, PTP-type (the warp yarn on the interface is perpendicular to each other) and T-type (the weft yarn on the interface is parallel to the pulling direction) interfaces softened first and then tended to plateau after reaching peak shear stress, and softening became more obvious at higher normal stresses. The displacement corresponding to peak shear stress (referred to as “peak displacement” in this paper) of interfaces was positively correlated with the normal stress, and the wet state reduced the interfacial peak displacement. For different types of interfaces, the peak displacement of the T-type interface was the largest, followed by PTP-type and P-type. Interfacial shear characteristics conformed to Mohr–Coulomb strength theory and, compared with quasi-cohesion values ranging from 1.334 to 3.606 kPa, the quasi-friction angle significantly contributed to the interfacial shear strength. The quasi-friction angle of the interface was composed of a sliding friction angle and an occlusal friction angle. The shear strength of the interface was more sensitive to the interface types than whether they were in the dry or wet state. For different types of interfaces and dry-wet states, the change in the interfacial shear strength is respectively affected by the occlusal friction angle and the sliding friction angle on the interface

Mechanical Alloying Synthesis of Co9S8 Particles as Materials for Supercapacitors

Cobalt sulfide (Co9S8) particles are compounded as the electrode materials of supercapacitors by a mechanical alloying method. They show excellent properties including good cycling stability and high specific capacitance. A supercapacitor is assembled using Co9S8 as the anode and activated carbon (AC) as the cathode. It gains a maximum specific capacitance of 55 F·g−1 at a current density of 0.5 A·g−1, and also an energy density of 15 Wh·kg−1. Those results show that the novel and facile synthetic route may be able to offer a new way to synthesize alloy compounds with excellent supercapacitive properties

A double cross-linked anisotropic quaternized chitosan/sodium alginate-based wound dressing for rapid drainage of biofluids

Excessive biofluid around wounds can cause infection and prevent healing. In this study, an anisotropic quaternized chitosan (QC)/sodium alginate (AL)-based aerogel wound dressing was prepared via a directional freeze-drying technique inspired by the channel structure used for water transport in trees. The aligned channels provided the dressing with self-pumping ability, allowing it to rapidly and completely remove biofluids and absorb biofluids up to 1292.5 % of its own weight. To enhance the strength of the dressing, a double cross-linked network was constructed based on the QC-AL electrostatic attraction and AL-Ca2+ chelation interaction. The axial compressive strength of the double cross-linked dressing reached 207.3 kPa (ε = 50 %). In addition, the dressing exhibited strong conductive properties (conductivity = 13.0 S/m), antioxidant activities [reactive oxygen species (ROS) scavenging ability = 88.0 %], and hemostatic characteristics (blood coagulation index = 1.8 %). The dressing also exhibited powerful antibacterial performance, exhibiting over 98.0 % inhibition of E. coli and S. aureus. Experiments on diabetic mouse models revealed that the dressing considerably promoted wound healing. On day 3, the wound healing rate was 96.7 % faster in the QAC group than in the gauze group. Therefore, the developed dressing may have great potential for chronic wound care

Deep UV Laser at 249 nm Based on GaN Quantum Wells

Deep UV Laser at 249 nm Based on GaN Quantum Well