During services of the Reformed Churches of South Africa (RCSA), certain psalms and Biblical hymns are used frequently, while others are almost never used. The objective of this study is to determine how the Psalter of 2003 can be used optimally. The model of Zerfass is used for the investigation. The final results of the study are presented in the form of a model that can enrich the optimal use of the Psalter 2003 as means of communication in the liturgy of the RCSA. In Chapters 2 and 3, a basic-theoretical investigation is conducted, with reference to perspectives from Scripture and history. The investigation reveals that music and songs had already played an important role in the church of the Old Testament, and that the Psalms had had a significant influence on the liturgy and the faith. In the New Testament, new hymns are found that supplement those from the Old Testament. The form in which these hymns were composed, was closely connected to the context whence these songs arose. The communication that a hymn effects, is achieved jointly by word and music, in the church of the New Testament and subsequently. Since the Reformation, a degree of separation arose between the songs used in the church and outside, but mutual influences are observed. In Chapters 4 and 5, attention is paid to metatheoretical perspectives, first in communication science, then in hymnology. It is in their singing that the congregation participates in the worship of a church service. Such singing is indeed the basic form of participation, which promotes communication among members of the congregation. In judging a metrical version of a Psalm, attention should especially be paid to the content, style of the text and the melody. In the empirical investigation, qualitative and quantitative methods are used. The investigation proceeds in three phases. In the first phase, information is obtained about the hymns that were sung in a number of congregations in the course of a year. In the second phase, a questionnaire was set and sent to ministers, organists and members of congregations. In the final phase, interviews were conducted with ministers and organists from five congregations. The data show that the hymn occupies an important place in the liturgy. However, the investigation reveals that this point of departure is not fully realised in practice, and some shortcomings are identified. In particular, there is a need for extension of the hymnody, especially by hymns from the New Testament. In Chapter 7, an indication is given of the factors that constrain the optimal use of the Psalter 2003 as means of worship in the church service. The most important problems are: • the incomplete utilisation of the full collection of hymns in the Psalter, • the underuse of the 2001 metrical version, • the repeated use of a small subset of hymns, • problems with the melodies and liturgical usefulness, • limitations in the training of ministers and organists, • resistance to the 2001 metrical version, • a lack of proper programmes to practice the new hymns, and • inadequate support and encouragement by church councils in respect of improving the skills of organists. In view of these problems, a model is proposed, which identifies the relationships among the role players / elements necessary to promote worshipping through singing: • the users of the Psalter 2001, viz. Ministers, organists and members of the congregations, together with the role of the church council, • the Psalter 2003 as hymn book, and • the possible extension of the current corpus of hymns. / Thesis (Ph.D. (Liturgics))--North-West University, Potchefstroom Campus, 2009.

During services of the Reformed Churches of South Africa (RCSA), certain psalms and Biblical hymns are used frequently, while others are almost never used. The objective of this study is to determine how the Psalter of 2003 can be used optimally. The model of Zerfass is used for the investigation. The final results of the study are presented in the form of a model that can enrich the optimal use of the Psalter 2003 as means of communication in the liturgy of the RCSA. In Chapters 2 and 3, a basic-theoretical investigation is conducted, with reference to perspectives from Scripture and history. The investigation reveals that music and songs had already played an important role in the church of the Old Testament, and that the Psalms had had a significant influence on the liturgy and the faith. In the New Testament, new hymns are found that supplement those from the Old Testament. The form in which these hymns were composed, was closely connected to the context whence these songs arose. The communication that a hymn effects, is achieved jointly by word and music, in the church of the New Testament and subsequently. Since the Reformation, a degree of separation arose between the songs used in the church and outside, but mutual influences are observed. In Chapters 4 and 5, attention is paid to metatheoretical perspectives, first in communication science, then in hymnology. It is in their singing that the congregation participates in the worship of a church service. Such singing is indeed the basic form of participation, which promotes communication among members of the congregation. In judging a metrical version of a Psalm, attention should especially be paid to the content, style of the text and the melody. In the empirical investigation, qualitative and quantitative methods are used. The investigation proceeds in three phases. In the first phase, information is obtained about the hymns that were sung in a number of congregations in the course of a year. In the second phase, a questionnaire was set and sent to ministers, organists and members of congregations. In the final phase, interviews were conducted with ministers and organists from five congregations. The data show that the hymn occupies an important place in the liturgy. However, the investigation reveals that this point of departure is not fully realised in practice, and some shortcomings are identified. In particular, there is a need for extension of the hymnody, especially by hymns from the New Testament. In Chapter 7, an indication is given of the factors that constrain the optimal use of the Psalter 2003 as means of worship in the church service. The most important problems are: • the incomplete utilisation of the full collection of hymns in the Psalter, • the underuse of the 2001 metrical version, • the repeated use of a small subset of hymns, • problems with the melodies and liturgical usefulness, • limitations in the training of ministers and organists, • resistance to the 2001 metrical version, • a lack of proper programmes to practice the new hymns, and • inadequate support and encouragement by church councils in respect of improving the skills of organists. In view of these problems, a model is proposed, which identifies the relationships among the role players / elements necessary to promote worshipping through singing: • the users of the Psalter 2001, viz. Ministers, organists and members of the congregations, together with the role of the church council, • the Psalter 2003 as hymn book, and • the possible extension of the current corpus of hymns. / Thesis (Ph.D. (Liturgics))--North-West University, Potchefstroom Campus, 2009.

The effect of strain (stress) on the below threshold output of InGaAsP diode lasers has been investigated theoretically and experimentally. The degree of polarization (DOP) and the polarization- resolved spectral output (PRSO) were obtained as a function of the external stress applied to the device. A correlation between the DOP and the peak of the PRSO as a function of the stress was found. This correlation suggests that below threshold, DOP can be used to measure the strain in the active region of lasers. A model based on a strain modified Shockley matrix for the band calculation and a strain modified dipole moment for the optical emission has been constructed to bridge the correlation between the DOP and PRSO. / Thesis / Master of Engineering (ME)

This master thesis presents a theoretical investigation of the energy and stability of interfaces in iron-carbide compounds, specifically focusing on the α-Fe/Cr7C3 system. The study aims to fill the gap in knowledge regarding the surface energetics of these interfaces using Density Functional Theory (DFT). Six different α-Fe/Cr7C3 interfaceswere constructed α-Fe(001)/Cr7C3(024), α-Fe(001)/Cr7C3(202), α-Fe(001)/Cr7C3(040),α-Fe(110)/Cr7C3(024), α-Fe(110)/Cr7C3(202) and α-Fe(110)/Cr7C3(040). Due to limited computational resources, only one of them was computationally analyzed to determine its interfacial energy value. The results revealed that the interfacial energy of the α-Fe(001)/Cr7C3(040) interface falls within the range of incoherent interfaces, indicating its stability. The computed interfacial energy values ranged from 0.94 to 3.39 J/m2, consistent with similar studies on other iron interfaces. The simulations also identified minimum and local minimum points in the interface energy curve, representing stable configurations at specific interface separation distances. The presence of a minimum point at an interface separation value of d = 1.3551 Å with an interfacial energy of 0.94 J/m2 indicates the most stable configuration, while a local minimum point at d = 2.27 Å with an interfacial energy of 2.12 J/m2 suggests another stable configuration for the interface. The conclusion that the computations were correctly performed with an interfacial energy value of 0.94 J/m2 for the most stable configuration at a supercell length (aSupercell ) of 22.23 Å is drawn. The findings of this research have significant implications for future investigations and applications. Firstly, this study fills the gap of the unresearched ferrite-carbide interfaces with theoretical data. Secondly, the knowledge gained from studying these interfaces contributes to understanding hydrogen interactions, which is fundamental for the transition towards a hydrogen economy. Additionally, the incoherent nature of the interface introduces challenges in understanding material behavior and properties, necessitating further investigations for designing efficient systems. Future work includes experimental validation of the α-Fe/Cr7C3 interface to compare the theoretical and experimental energies and stability. Investigating the remaining interfaces and examining the effects of introducing hydrogen atoms in these interfaces, along with calculating the corresponding hydrogen trapping energies, are important research areas. Further advancements in understanding these interfaces can be achieved through interface engineering, multiscale modeling, and studying other iron-carbide systems. / Detta examensarbete presenterar en teoretisk undersökning av energin och stabiliteten hos gränssnitt i järnkarbidföreningar och fokuserar specifikt på α-Fe/Cr7C3-systemet. Studien syftar till att fylla kunskaps tomrummet gällande ytegenskaperna hos dessa gränssnitt genom användning av densitetsfunktionalteori (DFT). Sex olika α-Fe/Cr7C3-gränssnitt konstruerades α-Fe(001)/Cr7C3(024), α-Fe(001)/Cr7C3(202), α-Fe(001)/Cr7C3(040), α-Fe(110)/Cr7C3(024), α-Fe(110)/Cr7C3(202) och α-Fe(110)/Cr7C3(040). På grund av begränsade beräkningsresurser analyserades endast ett av dem för att bestämma dess gränssnittsenergivärde. Resultaten visade att gränssnittsenergin för α-Fe(001)/Cr7C3(040)- gränssnittet ligger inom intervallet för inkoherenta gränssnitt, vilket indikerar dess stabilitet. De beräknade gränssnittsenergivärdena varierade mellan 0,94 och 3,39 J/m2 , vilket är i linje med liknande studier där järngränssnitt studeras. Minimi och lokala minimipunkter i gränssnittets energikurva, vilket representerar stabila konfigurationer vid specifika avstånd mellan gränssnittet. Förekomsten av en minimipunkt vid ett gränssnittsavstånd på d = 1,35 Å med en gränssnittsenergi på 0,94 J/m2 indikerar den mest stabila konfigurationen, medan en lokal minimipunkt vid d = 2,27 Å med en gränssnittsenergi på 2,12 J/m2 antyder en annan stabil konfiguration för gränssnittet. Slutsatsen dras att beräkningarna utfördes korrekt med ett gränssnittsenergivärde på 0,94 J/m2 för den mest stabila konfigurationen vid en supercellslängd (aSupercell) på 22,23 Å. Fynden från denna forskning har betydande implikationer för framtida undersökningar och tillämpningar. För det första fyller denna studie kunskapsgapet gällande de otillräckligt utforskade ferrit-karbidgränssnitten med teoretisk data. För det andra bidrar den erhållna kunskapen från studiet av dessa gränssnitt till förståelsen av väteinteraktioner, vilket är grundläggande för övergången till en väteekonomi. Dessutom innebär gränssnittets inkoherenta natur utmaningar när det gäller att förstå materialbeteende och egenskaper, vilket kräver ytterligare undersökningar för att utforma effektiva system. Framtida arbete inkluderar experimentell validering av gränssnittet mellan α-Fe/Cr7C3 för att jämföra teoretiska och experimentella energier och stabilitet. Att undersöka återstående gränssnitt och undersöka effekterna av att introducera väteatomer i dessa gränssnitt och beräkna motsvarande vätefällningsenergier är viktiga forskningsområden. Gränssnittsdesign, flerskalig modellering och studier av andra järnkarbid-system kan ytterligare främja förståelsen av dessa gränssnitt.