We consider a two-way relay channel in which two transmitters want to exchange information through a central relay. The relay observes a superposition of the trans- mitted signals from which a function of the transmitted messages is computed for broadcast. We consider the design of codebooks which permit the recovery of a function at the relay and derive information-theoretic bounds on the rates for reliable decoding at the relay. In the spirit of compute-and-forward, we present a multilevel coding scheme that permits reliable computation (or, decoding) of a class of functions at the relay. The function to be decoded is chosen at the relay depending on the channel realization. We define such a class of reliably computable functions for the proposed coding scheme and derive rates that are universally achievable over a set of channel gains when this class of functions is used at the relay. We develop our framework with general modulation formats in mind, but numerical results are presented for the case where each node transmits using 4-ary and 8-ary modulation schemes. Numerical results demonstrate that the flexibility afforded by our proposed scheme permits substantially higher rates than those achievable by always using a fixed function or considering only linear functions over higher order fields. Our numerical results indicate that it is favorable to allow the relay to attempt both compute-and-forward and decode-and-forward decoding. Indeed, either method considered separately is suboptimal for computation over general channels. However, we obtain a converse result when the transmitters are restricted to using identical binary linear codebooks generated uniformly at random. We show that it is impossible for this code ensemble to achieve any rate higher than the maximum of the rates achieved using compute-and-forward and decode-and-forward decoding. Finally, we turn our attention to the design of low density parity check (LDPC) ensembles which can practically achieve these information rates with joint-compute- and-forward message passing decoding. To this end, we construct a class of two-way erasure multiple access channels for which we can exactly characterize the performance of joint-compute-and-forward message passing decoding. We derive the processing rules and a density evolution like analysis for several classes of LDPC ensembles. Utilizing the universally optimal performance of spatially coupled LDPC ensembles with message passing decoding, we show that a single encoder and de- coder with puncturing can achieve the optimal rate region for a range of channel parameters.

In wireless communication systems, relays are widely used to extend coverage. Over the past years, relays have evolved from simple repeaters to more sophisticated units that perform signal processing to improve signal to interference plus noise ratio (SINR) or throughput (or both) at the destination receiver. There are various types of relays such as amplify and forward (AF), decode and forward (DF), and compress and forward (CF) (or estimate and forward (EF)) relays. In addition, recently there has been a growing interest in two-way relays (TWR). By utilizing the concept of analog network coding (ANC), TWRs can improve the throughput of a wireless sys- tem by reducing the number of time slots needed to complete a bi-directional message exchange between two destination nodes. It’s well known that the performance of a TWR system greatly depends on its ability to apply signal processing techniques to effectively mitigate the self-interference and noise accumulation, thereby improving the SINR. We study a TWR system that is equipped with multiple antennas at the relay node and a single antenna at the two destination nodes. Different from traditional work on TWR, we focus on the case with imperfect knowledge of channel state information (CSI). For such a TWR, we formulate a robust optimization problem that takes into ac- count norm-bounded estimation errors in CSI and designs an optimal beamforming matrix. Realizing the fact that this problem is extremely hard to solve globally, we derive two different methods to obtain either optimal or efficient suboptimal beam- forming matrix solutions. The first method involves solving the robust optimization problem using the S-procedure and semidefinite programming (SDP) with rank-one relaxation. This method provides an optimal solution when the rank-one relaxation condition for the SDP is satisfied. In cases where the rank-one condition cannot be satisfied, it’s necessary to resort to sub-optimal techniques. The second approach presented here reformulates the robust non-convex quadratically constrained quadratic programming (QCQP) into a robust linear programming (LP) problem by using first-order perturbation of the optimal non-robust beamforming solution (which assumes no channel estimation error). Finally, we view the TWR robust beamforming problem from a practical standpoint and develop a set of iterative algorithms based on Newton’s method or the steepest descent method that are practical for hardware implementation.

The rapid changes in the world of online technology during the last two decades brought along new challenges and opportunities for public relations practitioners. Literature has proven that the interactive capabilities of web-based technology have the possibility to build and maintain relationships with stakeholders and create two-way symmetrical communication opportunities. One such technology is an intranet, which could have an immense impact on an organisation's internal communication environment. If managed and applied correctly the intranet has the possibility to build two-way symmetrical relationships with an organisation's internal stakeholders - often described as one of the organisation's most strategic stakeholder groups. In this applied research study, the contribution of an international mining organisation's intranet to internal two-way symmetrical communication was explored and described. An extensive literature study was conducted to determine how an intranet could contribute theoretically to two-way symmetrical communication. The empirical findings were obtained by means of two main research methods: a qualitative content analysis and semi-structured interviews with middle management employees. The content analysis described how the basic principles of two-way symmetrical communication were applied on the Lonmin Platinum intranet. The semistructured interviews with middle management explored and described how they perceived and used the intranet with regard to two-way symmetrical communication. It was concluded that the Lonmin intranet did not contribute to two-way symmetrical communication. A critical conclusion is that an intranet as a mediated communication medium could not contribute to two-way symmetrical communication if the internal communication climate does not facilitate the specific values related to the Excellence Theory and two-way symmetrical communication principles. Another conclusion is that Lonmin's intranet was too technologically focussed. There was no management of strategic communication or ownership, and as a result the intranet did not contribute to two-way symmetrical communication in the organisation. It is suggested that future studies describe the contribution of the Lonmin intranet to two-way symmetrical communication after the communication department had commenced with strategic intranet management. The relation between the contribution of the intranet to two-way symmetrical communication in the organisation and the general communication climate could also be explored in future research studies. / Thesis (M.A. (Communication Studies))--North-West University, Potchefstroom Campus, 2007.

The rapid changes in the world of online technology during the last two decades brought along new challenges and opportunities for public relations practitioners. Literature has proven that the interactive capabilities of web-based technology have the possibility to build and maintain relationships with stakeholders and create two-way symmetrical communication opportunities. One such technology is an intranet, which could have an immense impact on an organisation's internal communication environment. If managed and applied correctly the intranet has the possibility to build two-way symmetrical relationships with an organisation's internal stakeholders - often described as one of the organisation's most strategic stakeholder groups. In this applied research study, the contribution of an international mining organisation's intranet to internal two-way symmetrical communication was explored and described. An extensive literature study was conducted to determine how an intranet could contribute theoretically to two-way symmetrical communication. The empirical findings were obtained by means of two main research methods: a qualitative content analysis and semi-structured interviews with middle management employees. The content analysis described how the basic principles of two-way symmetrical communication were applied on the Lonmin Platinum intranet. The semistructured interviews with middle management explored and described how they perceived and used the intranet with regard to two-way symmetrical communication. It was concluded that the Lonmin intranet did not contribute to two-way symmetrical communication. A critical conclusion is that an intranet as a mediated communication medium could not contribute to two-way symmetrical communication if the internal communication climate does not facilitate the specific values related to the Excellence Theory and two-way symmetrical communication principles. Another conclusion is that Lonmin's intranet was too technologically focussed. There was no management of strategic communication or ownership, and as a result the intranet did not contribute to two-way symmetrical communication in the organisation. It is suggested that future studies describe the contribution of the Lonmin intranet to two-way symmetrical communication after the communication department had commenced with strategic intranet management. The relation between the contribution of the intranet to two-way symmetrical communication in the organisation and the general communication climate could also be explored in future research studies. / Thesis (M.A. (Communication Studies))--North-West University, Potchefstroom Campus, 2007.

To investigate the ability for animals to understand human communication signals and the communication between animals and humans, scientists often investigate the understanding of human gestural cues. Dogs (Canis lupus familiaris) which have a long history of co-evolution with humans have been shown to make good use of human gestural cues. In the present study I investigated whether dogs in general understand a human pointing gesture and if there are differences between sex, age or breeds. In total 46 dogs of different breeds participated in the study. The study was carried out in a dog center in Linköping, Hundens och djurens beteendecenter. To test if dogs understand human pointing gestures, a two-way object choice test were used, where an experimenter pointed at a baited bowl at a distance of three meter from the dog. The results showed that dogs in general can understand human pointing gestures. However, no significant differences were found for sex, age or breeds. As a conclusion, I found that dogs in general can understand human pointing gestures, but sex, age or breed did not affect the ability.

Government of Canada communications professionals work in an increasingly challenging environment, characterized by an intrusive 24/7 media cycle, a frenetic pace of evolving communication technologies, layered accountability requirements, political tension, and waning public trust. Scholars call on professional communicators to help rebuild public trust, which is intrinsic to a healthy democratic government. The Three-dimensional Model for Transparency in Government Communication developed by Fairbanks, Plowman and Rawlins (2007) serves as the theoretical framework for investigating the Government of Canada’s approach to transparent citizen-focused communications from the perspective of communications professionals. The model’s adaptability to the Government of Canada context is tested through 23 qualitative semi-structured interviews with Government of Canada senior communications advisors, managers and executives. The data is analysed using constant comparative thematic analysis. The findings demonstrate that Government of Canada communicators strongly value transparency. Furthermore, the key components of the transparency model – communications practices, organizational support and provision of resources – encapsulate the factors that influence the practice of transparent citizen-focused communications by the Government of Canada. The study concludes by offering recommendations for future research and practical applications.

No description available.

Master of Science / Department of Architectural Engineering / Bill Zhang / In structural engineering, it can be challenging to incorporate a sustainable design without sacrificing structural integrity. However, flat plate voided slabs are an interesting alternative to standard flat plate concrete slab systems due to the reduction in concrete and the recycled plastic void formers that are located inside the slab. This research is necessary because an increased use of voided slabs in concrete structures would help fight climate change by reducing the CO₂ emissions caused from cement production. This report will discuss the advantages and disadvantages of implementing plastic void formers into solid flat plate slabs and examine a parametric study comparing voided flat plate slabs to solid flat plate slabs. The design of the voided slabs follows the CRSI Design Guide for Voided Concrete Slabs while also referencing the ACI 318-14 Building Code Requirements for Structural Concrete. Three different slabs for typical square bay sizes of 25 feet, 30 feet, and 35 feet are designed to compare the effectiveness of voided slabs to traditional solid slabs.

abstract: This dissertation considers two different kinds of two-hop multiple-input multiple-output (MIMO) relay networks with beamforming (BF). First, "one-way" amplify-and-forward (AF) and decode-and-forward (DF) MIMO BF relay networks are considered, in which the relay amplifies or decodes the received signal from the source and forwards it to the destination, respectively, where all nodes beamform with multiple antennas to obtain gains in performance with reduced power consumption. A direct link from source to destination is included in performance analysis. Novel systematic upper-bounds and lower-bounds to average bit or symbol error rates (BERs or SERs) are proposed. Second, "two-way" AF MIMO BF relay networks are investigated, in which two sources exchange their data through a relay, to improve the spectral efficiency compared with one-way relay networks. Novel unified performance analysis is carried out for five different relaying schemes using two, three, and four time slots in sum-BER, the sum of two BERs at both sources, in two-way relay networks with and without direct links. For both kinds of relay networks, when any node is beamforming simultaneously to two nodes (i.e. from source to relay and destination in one-way relay networks, and from relay to both sources in two-way relay networks), the selection of the BF coefficients at a beamforming node becomes a challenging problem since it has to balance the needs of both receiving nodes. Although this "BF optimization" is performed for BER, SER, and sum-BER in this dissertation, the solution for optimal BF coefficients not only is difficult to implement, it also does not lend itself to performance analysis because the optimal BF coefficients cannot be expressed in closed-form. Therefore, the performance of optimal schemes through bounds, as well as suboptimal ones such as strong-path BF, which beamforms to the stronger path of two links based on their received signal-to-noise ratios (SNRs), is provided for BERs or SERs, for the first time. Since different channel state information (CSI) assumptions at the source, relay, and destination provide different error performance, various CSI assumptions are also considered. / Dissertation/Thesis / Ph.D. Electrical Engineering 2012

xviii, 278 p. : ill. (some col.) / Two-way immersion (TWI) programs teach English Learners (ELs) and native English speakers in the same classroom using both languages in an immersion approach. Studies suggest that TWI programs result in greater student integration, thus providing a promising alternative for Spanish speaking ELs, who are frequently concentrated in high poverty, majority-minority schools. This study used a mixed methods research design to examine student integration issues in two elementary schools. Enrollment data from 1999-2009 were analyzed using both descriptive and inferential statistics. Grounded theory was used to analyze data from interviews, focus groups, observations, and archival documents. The demographic analyses revealed trends that are consistent with demographic changes nationally: an increasing Latino population and a decreasing White population. In terms of instructional integration patterns, the following findings were consistent for both schools. Prior to the introduction of TWI, students with Individualized Education Programs (IEPs) were evenly distributed among 4th/5th grade classrooms. After TWI, significantly more students with IEPs were in the English only than in TWI classes. In addition, after TWI, significantly more English speakers who qualified for free/reduced meals were found in the English only classes. However, Spanish speakers, who were almost exclusively located in TWI, had significantly higher free/reduced meals rates than English speakers in either TWI or English only classes. The central theme to emerge in the grounded theory study was "Negotiating the Value of Spanish," a process that occurred over many years as both schools grappled with a growing Latino population. Using Bourdieu's concept of cultural capital, I suggest that the introduction of TWI commodified Spanish within the mainstream educational program, providing cultural capital gains for Spanish speakers as a result. TWI provided the justification and resources for hiring more bilingual staff, for purchasing Spanish curriculum materials, for providing professional development in Spanish and about Spanish literacy, for increasing outreach to Spanish speaking families, and for prioritizing Spanish speakers' access to the program. Spanish speakers and their families thus gained greater access to the curriculum and the life of the school, and staff began to see Spanish speakers differently. / Committee in charge: Joseph Stevens, Chairperson; Gerald Rosiek, Member; Edward Olivos, Member; Leanne Ketterlin, Geller Member; Lynn Stephen, Outside Member