Secure communication under channel uncertainty is an important and challenging problem in physical-layer security and cryptography. In this dissertation, we take a fundamental information-theoretic view at three concrete settings and use them to shed insight into efficient secure communication techniques for different scenarios under channel uncertainty. First, a multi-input multi-output (MIMO) Gaussian broadcast channel with two receivers and two messages: a common message intended for both receivers (i.e., channel uncertainty for decoding the common message at the receivers) and a confidential message intended for one of the receivers but needing to be kept asymptotically perfectly secret from the other is considered. A matrix characterization of the secrecy capacity region is established via a channel-enhancement argument and an extremal entropy inequality previously established for characterizing the capacity region of a degraded compound MIMO Gaussian broadcast channel. Second, a multilevel security wiretap channel where there is one possible realization for the legitimate receiver channel but multiple possible realizations for the eavesdropper channel (i.e., channel uncertainty at the eavesdropper) is considered. A coding scheme is designed such that the number of secure bits delivered to the legitimate receiver depends on the actual realization of the eavesdropper channel. More specifically, when the eavesdropper channel realization is weak, all bits delivered to the legitimate receiver need to be secure. In addition, when the eavesdropper channel realization is strong, a prescribed part of the bits needs to remain secure. We call such codes security embedding codes, referring to the fact that high-security bits are now embedded into the low-security ones. We show that the key to achieving efficient security embedding is to jointly encode the low-security and high-security bits. In particular, the low-security bits can be used as (part of) the transmitter randomness to protect the high-security ones. Finally, motivated by the recent interest in building secure, robust and efficient distributed information storage systems, the problem of secure symmetrical multilevel diversity coding (S-SMDC) is considered. This is a setting where there are channel uncertainties at both the legitimate receiver and the eavesdropper. The problem of encoding individual sources is first studied. A precise characterization of the entire admissible rate region is established via a connection to the problem of secure coding over a three-layer wiretap network and utilizing some basic polyhedral structure of the admissible rate region. Building on this result, it is then shown that the simple coding strategy of separately encoding individual sources at the encoders can achieve the minimum sum rate for the general S-SMDC problem.

The servo mechatronic system design process usually covers two different engineering domains: structure design and system control. The relationship between these two domains is much closed. In order to reduce the disturbance caused by parameters in either one, the domain knowledge from those two different fields needs to be integrated. Thus, in order to reduce the disturbance caused by parameters in either one, the mechanical and controller design domains need to be integrated. Therefore, the integrated design method Design For Control (DFC), will be employed in this thesis. In this connect, it is not only applied to achieve minimal power consumption but also enhance structural performance and system response at same time. To investigate for the integrated design method, there are two common servo mechatronic systems: feed drive system and legged servo mechatronic system are used as the design platform. 1. Mechatronic Feed Drive System To investigate the method for integrated optimization, a mechatronic feed drive system of the machine tools is used as a design platform. The 3D software, Pro/Engineer is first used to build the 3D model to analyze and design structure parameters such as elastic deformation, nature frequency and component size, based on their effects and sensitivities to the structure. Additionally, in order to achieve system robust, Quantitative Feedback Theory (QFT), will be applied to determine proper control parameters for the controller. Therefore, overall physical properties of the machine tool will be obtained in the initial stage. Following this Design Then Control process, the iterative design process is following to enhance some of system performance. Finally, the technology design for control will be carried out to modify the structural and control parameters to achieve overall system performance. Hence, the corresponding productivity is expected to be greatly improved. 2. Legged Servo Mechatronic System The goal of this study is to develop a one-degree-of-freedom (DOF) legged servo mechatronic system with DFC. For this system, the kinematics and control dynamic analysis of legged servo mechatronic system have been solved by using four bar linkage with symmetrical coupler point, pantograph, and common position and velocity controller. In addition, in order to improvement system dynamic performance and reduce the control cost, the counterweight, that base on mass redistribution is employed to integrate structure and control into one design step for reduce shaking moment. Additionally, in order to improvement the system performance, the complete force balance is not only to take advantage of control cost, but also easy to control.

The public relations field is rapidly adopting two-way symmetrical communications as a way to achieve excellence and win-win solutions for multiple publics. This paper focuses on activism and industry public relations approaches involving a group of expert physicians in Houston and the medical devices industry. After exploring two-way symmetrical communications and the Excellence Theory of Public Relations, the paper explores these physicians’ viewpoints and provides an overview of the medical device industry. The discussion then provides public relations suggestions for the physicians to symmetrically approach the industry to create change. Next, the paper recommends how the medical device industry can respond to work with the physicians and to prevent possible public relations damage and crisis. The paper concludes by expressing the importance of applying symmetrical communications methods to solve challenges and create win-win solutions. / text

This study examines the party-controlled communication of the five most important political parties in the North West Province of South Africa during the 1999 general elections. The main assumption is that political parties in developing democracies have a normative obligation to do more than canvas for votes during an election campaign. Political parties should also be instrumental through their communication in fostering a democratic political culture. Central to this argument is the notion that a typical marketing approach is not suitable for an election campaign in a developing democracy. In accordance with the participatory approach to development, it is thus proposed that the two-way symmetrical model for public relations (as proposed by James Grunig) is a more appropriate approach to election campaigns. Especially relevant for this study is the two-way symmetrical model's emphasis on interaction and the establishment of long tern relationships with target publics. Through an extensive qualitative analysis of all relevant material (party manifests, newspaper advertisements, radio advertisements, pamphlets, posters and web pages), it was found that South African political parties placed much less emphasis on the "image" of the party or its leader compared to their American counterparts. However, that did not imply that the substance of the message was emphasised adequately. On the contrary, the political parties participating in the elections in the North-West province generally failed the normative criteria of informing voters and identifying democratic values adequately. Furthermore it was found that the cognitive and emotional campaign messages were not fully integrated. While the focus was on typical election issues (emotional message), these issues were not explained and contextualised within a developing democracy to the full extend (cognitive message). Therefore the emotional message was not utilised to focus the voter's attention on policy issues and democratic values. In conclusion it is argued that political parties should do much more than merely canvas for votes. They should also empower voters by informing them on their policy issues and highlighting democratic values in society. Only then the new South African democracy will be sustainable. / Thesis (Ph.D. (Communication Studies))--North-West University, Potchefstroom Campus, 2004.

Asimetrinė fazinių įtampų sistema stipriai pablogina asinchroninių variklių darbą. Tyrimo tikslas – ištirti trifazio asinchroninio variklio darbą, esant įvairioms maitinimo įtampos fazorių modulių asimetrijoms. Asinchroninio variklio visi energetiniai rodikliai apskaičiuoti atlikus jų tuščiosios veikos ir apkrovos bandymus bei panaudojus atskirų galios nuostolių metodą. Įtampos asimetriškumo lygis gaunamas panaudojus simetrinių dedamųjų metodą. Atsiradus asimetrijai, asinchroninio variklio oro tarpe kuriamas elipsinis sukamasis magnetinis laukas, kuris sukelia variklyje ir sukimo, ir stabdymo momentus. Tik esant simetrinei fazinių įtampų sistemai (ka = 0 %), prie variklio nurodytosios apkrovos visi kiti dydžiai gaunami nurodytieji. Teoriškai ir eksperimentiškai ištyrus 1,1 kW galios asincroninį elektros variklį gauta, kad esant asimetrinei fazinių įtampų sistemai (ka = 11 %), prie nurodytosios apkrovos asinchroninio variklio iš tinklo vartojama galia P1 padidėjo 22,4 %, apsisukimai n sumažėjo, o slydimas s padidėjo 94,7 %, galios nuostoliai ΣP padidėjo 101 %, elektromagnetinis momentas Mem padidėjo 4,9 %, naudingumo koeficientas η sumažėjo 21,4 % ir galios koeficientas cos φ sumažėjo 0,9 %. / Asymmetrical phase system of voltages significantly degrades induction motors work. The study objective - to explore the three-phase asynchronous motor at different power supply modules vector asymmetry. All energetic indicators of the asynchronous motor winding were calculated after performing their no-load and load testing, and using the method of separate power loss. Asymmetry voltage level obtained by using the method of symmetrical components. The emergence of asymmetry in the induction motor air gap created elliptical rotary magnetic field, which caused an engine torque and braking points. Only a symmetrical phase voltage system (ka = 0%), the given load on the engine all the other values given are obtained. Theoretical and experimental study of 1,1 kW electric asynchronous motor revealed that in asymmetric phase voltage system (ka = 11%), at the given induction motor load from the mains power is used in P1 increased by 22,4%, n speed decreased and the slip increased by 94,7%, power ΣP loss has increased 101%, the electromagnetic torque Mem increased by 4,9%, the efficiency η decreased 21,4% and power factor cos φ decreased by 0,9%.

The solid oxide fuel cell (SOFC) is a potential high efficient electrochemical device for vehicles, auxiliary power units and large-scale stationary power plants combined heat and power application. The main challenges of this technology for market acceptance are associated with cost and lifetime due to the high temperature (700-1000 oC) operation and complex cell structure, i.e. the conventional membrane electrode assemblies. Therefore, it has become a top R&amp;D goal to develop SOFCs for lower temperatures, preferably below 600 oC. To address those above problems, within the framework of this thesis, two kinds of innovative approaches are adopted. One is developing functional composite materials with desirable electrical properties at the reduced temperature, which results of the research on ceria-based composite based low temperature ceramic fuel cell (LTCFC). The other one is discovering novel energy conversion technology - Single-component/ electrolyte-free fuel cell (EFFC), in which the electrolyte layer of conventional SOFC is physically removed while this device still exhibits the fuel cell function. Thus, the focus of this thesis is then put on the characterization of materials physical and electrochemical properties for those advanced energy conversion applications. The major scientific content and contribution to this challenging field are divided into four aspects except the Introduction, Experiments and Conclusions parts. They are: Continuous developments and optimizations of advanced electrolyte materials, ceria-carbonate composite, for LTCFC. An electrolysis study has been carried out on ceria-carbonate composite based LTCFC with cheap Ni-based electrodes. Both oxygen ion and proton conductance in electrolysis mode are observed. High current outputs have been achieved at the given electrolysis voltage below 600 oC. This study also provides alternative manner for high efficient hydrogen production.  Compatible and high active electrode development for ceria-carbonate composite electrolyte based LTCFC. A symmetrical fuel cell configuration is intentionally employed. The electro-catalytic activities of novel symmetrical transition metal oxide composite electrode toward hydrogen oxidation reaction and oxygen reduction reaction have been experimentally investigated. In addition, the origin of high activity of transition metal oxide composite electrode is studied, which is believed to relate to the hydration effect of the composite oxide. A novel all-nanocomposite fuel cell (ANFC) concept proposal and feasibility demonstration. The ANFC is successfully constructed by Ni/Fe-SDC anode, SDC-carbonate electrolyte and lithiated NiO/ZnO cathode at an extremely low in-situ sintering temperature, 600 oC. The ANFC manifests excellent fuel cell performance (over 550 mWcm-2 at 600 oC) and a good short-term operation as well as thermo-cycling stability. All results demonstrated its feasibility and potential for energy conversion. Fundamental study results on breakthrough research Single-Component/Electrolyte-Free Fuel Cell (EFFC) based on above nanocomposite materials (ion and semi-conductive composite) research activities. This is also the key innovation point of this thesis. Compared with classic three-layer fuel cells, EFFC with an electrolyte layer shows a much simpler but more efficient way for energy conversion. The physical-electrical properties of composite, the effects of cell configuration and parameters on cell performance, materials composition and cell fabrication process optimization, micro electrochemical reaction process and possible working principle were systematically investigated and discussed. Besides, the EFFC, joining solar cell and fuel cell working principle, is suggested to provide a research platform for integrating multi-energy-related device and technology application, such as fuel cell, electrolysis, solar cell and micro-reactor etc. This thesis provides a new methodology for materials and system innovation for the fuel cell community, which is expected to accelerate the wide implementation of this high efficient and green fuel cell technology and open new horizons for other related research fields. / <p>QC 20131122</p>

In order to engage employees effectively, organisations need to practice two-way communication within a symmetrical worldview. This will encourage employees to feel valued, to participate in decision-making and contribute to obtaining organisational goals. Practising two-way communication will help to build stronger relationships between employees and managers, leading to increased employee engagement. Thus, the better the communication between managers and employees, the more engaged employees will be. Furthermore, the selection of communication channels can impact on the success of the message that is sent. Research has shown that if the inappropriate communication channel is selected when communicating with employees, the message might not be effectively received and understood. New technology, specifically Facebook can be introduced to provide an open and transparent channel for communication. Facebook can also facilitate two-way communication, which can lead to increased employee engagement. The literature study conducted informed the interview schedules that were developed and used to conduct semi-structured interviews with managers and focus group interviews with employees within two organisations in the South African financial sector. This was done in order to understand their expectations regarding the use of Facebook as an internal communication channel to enhance employee engagement. In terms of the conclusions derived from the empirical research, it seems evident that Facebook could be used as an additional internal communication channel to enhance employee engagement. Trust remains a very important factor in that managers should trust employees to use the channel in an ethical manner and employees should trust the organisation and its managers that they may voice their opinion freely, without the fear of victimisation. Facebook can be used to promote engagement on a social level to build relationships inside the organisation. However, managers and employees can together create a contract of understanding that will form the outline for a policy that will govern the use of Facebook. The parties involved can then negotiate the terms of this contract of understanding to ensure that all expectations regarding the use Facebook are met. / MA (Communication Studies), North-West University, Potchefstroom Campus, 2013

In order to engage employees effectively, organisations need to practice two-way communication within a symmetrical worldview. This will encourage employees to feel valued, to participate in decision-making and contribute to obtaining organisational goals. Practising two-way communication will help to build stronger relationships between employees and managers, leading to increased employee engagement. Thus, the better the communication between managers and employees, the more engaged employees will be. Furthermore, the selection of communication channels can impact on the success of the message that is sent. Research has shown that if the inappropriate communication channel is selected when communicating with employees, the message might not be effectively received and understood. New technology, specifically Facebook can be introduced to provide an open and transparent channel for communication. Facebook can also facilitate two-way communication, which can lead to increased employee engagement. The literature study conducted informed the interview schedules that were developed and used to conduct semi-structured interviews with managers and focus group interviews with employees within two organisations in the South African financial sector. This was done in order to understand their expectations regarding the use of Facebook as an internal communication channel to enhance employee engagement. In terms of the conclusions derived from the empirical research, it seems evident that Facebook could be used as an additional internal communication channel to enhance employee engagement. Trust remains a very important factor in that managers should trust employees to use the channel in an ethical manner and employees should trust the organisation and its managers that they may voice their opinion freely, without the fear of victimisation. Facebook can be used to promote engagement on a social level to build relationships inside the organisation. However, managers and employees can together create a contract of understanding that will form the outline for a policy that will govern the use of Facebook. The parties involved can then negotiate the terms of this contract of understanding to ensure that all expectations regarding the use Facebook are met. / MA (Communication Studies), North-West University, Potchefstroom Campus, 2013

This study examines the party-controlled communication of the five most important political parties in the North West Province of South Africa during the 1999 general elections. The main assumption is that political parties in developing democracies have a normative obligation to do more than canvas for votes during an election campaign. Political parties should also be instrumental through their communication in fostering a democratic political culture. Central to this argument is the notion that a typical marketing approach is not suitable for an election campaign in a developing democracy. In accordance with the participatory approach to development, it is thus proposed that the two-way symmetrical model for public relations (as proposed by James Grunig) is a more appropriate approach to election campaigns. Especially relevant for this study is the two-way symmetrical model's emphasis on interaction and the establishment of long tern relationships with target publics. Through an extensive qualitative analysis of all relevant material (party manifests, newspaper advertisements, radio advertisements, pamphlets, posters and web pages), it was found that South African political parties placed much less emphasis on the "image" of the party or its leader compared to their American counterparts. However, that did not imply that the substance of the message was emphasised adequately. On the contrary, the political parties participating in the elections in the North-West province generally failed the normative criteria of informing voters and identifying democratic values adequately. Furthermore it was found that the cognitive and emotional campaign messages were not fully integrated. While the focus was on typical election issues (emotional message), these issues were not explained and contextualised within a developing democracy to the full extend (cognitive message). Therefore the emotional message was not utilised to focus the voter's attention on policy issues and democratic values. In conclusion it is argued that political parties should do much more than merely canvas for votes. They should also empower voters by informing them on their policy issues and highlighting democratic values in society. Only then the new South African democracy will be sustainable. / Thesis (Ph.D. (Communication Studies))--North-West University, Potchefstroom Campus, 2004.

Surveys show that consumers tend to avoid traditional marketing channels, leading the practitioners to use earned media channels through public relations (PR). This has also led to the use of covert PR. To understand the use of this communications method, the purpose of this thesis is to study campaigns, which have gained transmission in social media, by investigating how practitioners of three different campaigns motivate the choice to use covert PR. The study is based on a hermeneutic methodology and has an abductive approach. It is carried out by semi-structured elite interviews with six contributors of three different campaigns, using covert PR. The primary data consists of the empery of the interviews, while the secondary data consists of a theoretical framework of excellence in public relations, the PR practice and viral messages. The result of the study indicates the point of view that covert PR has given the campaigns a wider reach. Furthermore the campaigns are described as having gained an extensive viral transmission, which exceeded the expectations of the interviewees. Nevertheless none of the practitioners think they will do a similar campaign again, it seems that they are aware of the risk of covert PR reducing the organisation’s reputation. The analysis also show a contradiction between the interviewees’ position and the presented theory, which might be caused by a perspective on PR as a way of spreading information rather than creating relationships. / Undersökningar visar att konsumenter i allt större utsträckning undviker reklam, vilket har gjort att kommunikationspraktiker i större utsträckning väljer förtjänade kanaler, eller public relations (PR), för att nå sina målgrupper. En följd av det är PR-aktiviteter med dolda avsändare. Med utgångspunkt i den debatt som finns kring metoden är syftet med studien att undersöka PR som fått viral spridning med avseende på hur tre kampanjer utformats och hur praktikerna bakom dessa i efterhand motiverar och resonerar kring valet av dold viral PR. För att få förståelse för fenomenet och varför sådana kampanjer genomförs har studien ett hermeneutiskt förhållningssätt och en abduktiv ansats. Undersökningen har genomförts med en kvalitativ metod genom semistrukturerade elitintervjuer med sex stycken praktiker som jobbat med någon av tre valda kampanjer. Det empiriska materialet i form av intervjuerna utgör studiens primärdata, medan dess sekundärdata består av teorier och tidigare forskning om excellens i public relations, PR i praktiken och viral spridning i sociala medier. Resultatet visar att den dolda avsändaren och dess avslöjande anses bidra till viral spridning. Kampanjerna motiveras med att de nått stora målgrupper, väckt debatt och varit underhållande – och räckvidden har överträffat praktikernas förväntningar. Ändå nämner alla att det inte är önskvärt att förknippas med metoden. Respondenternas utsagor går till viss del emot teorins normativa resonemang, vilket möjligtvis skulle kunna förklaras av en syn på PR som informationsspridande snarare än relationsskapande.