Multi-Walled Carbon Nanotubes Composites for Microwave Absorbing Applications

The response of materials to impinging electromagnetic waves is mainly determined by their dielectric (complex permittivity) and magnetic (complex permeability). In particular, radar absorbing materials are characterized by high complex permittivity (and eventually large values of magnetic permeability), Indeed, energy dissipation by dielectric relaxation and carrier conduction are principally responsible for diminishing microwave radiation reflection and transmission in non-magnetic materials. Therefore, the scientific and technological community has been investigating lightweight composites with high dielectric permittivity in order to improve the microwave absorption (i.e., radar cross-section reduction) in structural materials for the aerospace industry. Multiwalled carbon nanotubes films and their composites with different kind of polymeric resins are regarded as promising materials for radar absorbing applications because of their high permittivity. Nanocomposites based on commercial multi-wall carbon nano-tube (MWCNT) fillers dispersed in an epoxy resin matrix were fabricated. The morphology of the filler was analyzed by Field emission scanning electron microscopy (FESEM) and Raman spectroscopy, while the complex permittivity and the radiation reflection coefficient of the composites was measured in the radio frequency range. The reflection coefficient of a single-layer structure backed by a metallic plate was simulated based on the measured permittivity. Simulation achievements were compared to the measured reflection coefficient. Besides, the influence of morphological MWCNT parameters (i.e., aspect ratio and specific surface area) on the reflection coefficient was evaluated. Results verify that relatively low weight percent of MWCNTs are suitable for microwave absorption applications when incorporated into polymer matrix (i.e., epoxy resin)

Curriculum Decisions: Assessing and Updating IS Curriculum

The increased level of accountability in higher education has prompted many vomputer-related programs to seek accreditation. As accrediting agencies continue to define and refine exactly what these degrees should entail, institutions struggle with the decisions of aligning their curriculum with a dynamic set of standards set by an outside agency, focusing on the needs identified by their own assessment data, or attempting to marry the two. This paper details how one institution completed comprehensive reviews of their curriculum under two different projects: Expanding Pathways for Educational Development and Information Technology Experiences, an NSF-funded research project investigation and examination of curriculum and regional needs and an ABET evaluation and site visit. The focus of this report is to inform others of local efforts that may be replicated on their campuses, share findings that may be of use to others in similarly situated circumstances, and add to the assessment and accreditation dialog

Microwave characterization of polymer composite based on Biochar: A comparison of composite behaviour for Biochar and MWCNTs

In this work, Biochar is used as a filler in Epoxy resin for composite preparation. The electrical characteristics of composites are analyzed in function of different filler percentages. Results obtained are compared with composites based on multi-wall carbon nanotubes

PREVENTING DATA LEAKS FROM APPLICATION SCREEN-SHARING

According to a recent and comprehensive analysis of information security breaches, 23% of attacks are attributable to internal instances. Presented herein are techniques for protecting businesses against the sharing of confidential information within applications with unauthorized meeting participants. In particular, techniques presented herein restrict screen sharing of confidential information by preventing confidential content from being displayed on an unauthorized user’s endpoint device during a collaboration session

Validation of Two Nonlinear System Identification Techniques Using an Experimental Testbed

The identification of a nonlinear system is performed using experimental data and two different techniques, i.e. a method based on the Wavelet transform and the Restoring Force Surface method. Both techniques exploit the system free response and result in the estimation of linear and nonlinear physical parameters

Stochastic control applied to the ISWEC Wave Energy System

ISWEC (Inertial Sea Wave Energy Converter) is a fl oating marine device able to harvest sea waves energy by the interaction between the pitching motion of a fl oater and a spinning fl ywheel which can drive an electric PTO. In the ISWEC the hull dynamics is governed and controlled by the gyroscopic torque. The optimal control logic results in tuning the fl oater dynamics to the incoming waves in order to maximize the power transfer from the waves to the fl oater. In this paper the control problems of the ISWEC are stated and a control scheme based on the sub-optimal stochastic control logic is presented. The control scheme here presented has been tested using real wave records acquired at the deployment location in Pantelleria Island, which is one of the most energetic sites of the Mediterranean Sea

Mechanical properties of epoxy/multi-walled carbon nanotubes composites

In this paper, two types of multi-wall carbon nanotubes (MWCNTs) were dispersed into two different epoxy resins b high - shear mixing. Dispersion and homogenisation of nanofillers was analysed by Field Emission Scanning Electron Microscopy (FESEM). Microhardness of epoxy/MWCNTs nanocomposites, as well as of neat epoxy resins, is measure by Vickers method. The evolution of nanocomposites microhardness values were studied in function of curing time takin in account the influence of two different epoxy matrix and MWCNTs. Asymptotic values were analysed and compare with those of pure epoxy resin