Performance of a Multiple-Access DCSK-CC System over Nakagami-mm Fading Channels

In this paper, we propose a novel cooperative scheme to enhance the performance of multiple-access (MA) differential-chaos-shift-keying (DCSK) systems. We provide the bit-error-rate (BER) performance and throughput analyses for the new system with a decode-and-forward (DF) protocol over Nakagami-$m$ fading channels. Our simulated results not only show that this system significantly improves the BER performance as compared to the existing DCSK non-cooperative (DCSK-NC) system and the multiple-input multiple-output DCSK (MIMO-DCSK) system, but also verify the theoretical analyses. Furthermore, we show that the throughput of this system approximately equals that of the DCSK-NC system, both of which have prominent improvements over the MIMO-DCSK system. We thus believe that the proposed system can be a good framework for chaos-modulation-based wireless communications.Comment: 4 pages, 5 figures, accepted, IEEE ISCAS, 201

Gelation mechanism, synthesis, characterization, and applications of bio-based and model thermoplastic elastomers via RAFT polymerization

This dissertation report focuses on block copolymers derived from biomass along with a model methacrylate system to study the gelation behavior during reversible addition-fragmentation chain transfer (RAFT) polymerization due to the multi-functionality of bio-derived monomers. There are two bio-based block copolymer systems disclosed in this report. One is poly(styrene-blockacrylated epoxidized soybean oil) (PS-PAESO) derived from soybean oil. Thanks to the architecture of triglycerides, PS-PAESO block copolymers are found to resemble star block copolymers at low degree of polymerization (DP) and bottlebrush block copolymers at high DP. The long aliphatic chains of AESO act as the star arms in the former case while they become the side chain brushes in the latter case. At high DP, these PAESO brushes stiffen the primary chain and cause crowding. The self assembly of PS-PAESO block copolymers thus have unusual microdomain expansion without paying a severe entropy penalty. The domain spacing of the microstructures can be in the submicron scale. The investigation of PS-PAESO self assembly is conducted by small angle x-ray scattering (SAXS), transmission electron microscopy (TEM), and rheology. Understanding the structure-property relationship of PS-PAESO block copolymers reveals that the incorporation of bio-based materials in polymers has the potential for novel applications for their new structures. Another bio-based block copolymers covered in this dissertation is the glycerol-based block copolymers. Glycerol, the byproduct of biodiesel production is cheap and abundant. Developing new applications out from glycerol is therefore appealing. In this dissertation we used glycerol derivatives, acrylated glycerol and solketal acrylate to develop pressure sensitive adhesives (PSAs). Two (meth)acrylate-based block copolymers, poly(methyl methacrylate-block-acrylated glycerol) (MMAAG) and poly(isobornyl acrylate-block-solketal acrylate-block-isobornyl acrylate) (IBASA) were synthesized via RAFT polymerization. The formulation of PSAs includes only plasticizer and the elastomers without any tackifier thanks to elastomers self tack. The structureproperty relationship of these formulations was studied by rheology and peel tests. PSAs were conditioned at different humidity, adherends, and peel rates to test their peel adhesion. IBASA formulations showed comparable performance as commercial 3M ScotchTM magic tape after plasticized by benzoate esters. This result indicates that substituting petroleum-based PSAs with biobased PSAs are feasible. Since monomers of block copolymer systems revealed in this report tend to crosslink owing their multi-functional features, understanding their gelation behavior during synthesis becomes important. A model system composed of methyl methacrylate and ethylene glycol dimethacrylate was introduced to study the gelation behavior at high DP. A new parameter, the crosslinking tendency (CT) was introduced to predict the gelation conversion of controlled radical polymerization systems including RAFT and atom transfer radical polymerization. The CT analysis takes the system concentration into account which gives a better prediction than the conventional FloryStockmayer gelation theory. Through CT correlation, the reaction condition of intramolecular and intermolecular crosslinking can be distinguished. That is, the gelation suppression due to intramolecular crosslinking is accounted for in CT analysis. CT quantitatively describes many RAFT and ATRP systems implying that factors including monomer architectures and radical controlling mechanisms may not be as vital in gelation suppression

Lightsup: Modern Organization for the Modern Living Room

Studies show a cluttered home makes people feel anxious, helpless and overwhelmed. Home should be a place where people can relax and live comfortably. A messy house can lead to negative behavior, making people impatient and argumentative. An organized house can not only make people be in a good mood but also encourage harmonious relationships in a family. This paper puts forth how design can help people be more organized in their homes thus creating a relaxing environment. The research shows how clutter affects people’s behaviors, emotions and relationships; why people do not organize; and the importance of finding a home for belongings within the home. In the next part, the author proposes a possible solution and its application in tracking objects to help organize people in their rooms better through reminders and alerts. This interaction helps cultivate the hobby to maintain the organization in the house. At the end of the paper, the author mentions the future potential of this solution

Performance of Joint Channel and Physical Network Coding Based on Alamouti STBC

This work considers the protograph-coded physical network coding (PNC) based on Alamouti space-time block coding (STBC) over Nakagami-fading two-way relay channels, in which both the two sources and relay possess two antennas. We first propose a novel precoding scheme at the two sources so as to implement the iterative decoder efficiently at the relay. We further address a simplified updating rule of the log-likelihood-ratio (LLR) in such a decoder. Based on the simplified LLR-updating rule and Gaussian approximation, we analyze the theoretical bit-error-rate (BER) of the system, which is shown to be consistent with the decoding thresholds and simulated results. Moreover, the theoretical analysis has lower computational complexity than the protograph extrinsic information transfer (PEXIT) algorithm. Consequently, the analysis not only provides a simple way to evaluate the error performance but also facilitates the design of the joint channel-and-PNC (JCNC) in wireless communication scenarios.Comment: 6 pages, 4 figures, accpete

Optical fiber multiplexing interferometer system with a single laser diode and its application to online displacement measurement

A multiplexed optical fiber Michelson interferometer system that is self-referenced with a stabilizing feedback loop is presented. This system employs fiber Bragg gratings and wavelength division multiplexing technique to combine two optical fiber interferometers that share the same optical path in the main part of the optical system. When one Michelson interferometer, which uses the fiber Bragg gratings as reflective mirrors and is used as reference interferometer, is stabilized by an electric feedback loop, the other interferometer, which is used for the measurement, is also stabilized. This system is therefore suitable for online precision measurement. An active phase-tracking technique is applied for signal processing to achieve high resolution