Abstract The objectives of the current study were to evaluate the estrous response and pregnancy rate following timed artificial insemination (TAI) with frozen-thawed semen in cows. The study was carried out in cows at different villages of KwaZulu-Natal (KZN; n = 160) and Limpopo provinces (L; n = 171). Cows were selected randomly as presented by the farmers, regardless of parity, age, breed and body weight following pregnancy diagnosis. The cows were grouped according to breed type and body condition score (BCS) on a scale of 1 - 5. Selected cows were inserted a controlled intravaginal drug release (CIDR®) and removed on day 8, followed by administration of prostaglandin. Heat was observed on day 9 with the aid of heat mount detectors (HMD) that were placed on the individual cow’s tail head. Cows on heat were then inseminated twice at 12 hours interval. Pregnancy diagnosis was performed by an ultra-sound scanner and rectal palpation 90 days after TAI. Data were analyzed using SAS 2006. Estrous responses were 100% in KZN and 99% in Limpopo. The lowest pregnancy rate was recorded in Brahman and Bonsmara type cows with BCS ≤ 2.5 regardless of province. Interestingly, Nguni type cows with BCS ≤ 2.5 had higher average pregnancy rate of 59.5% in Limpopo and 53.5% in KZN. However, cows with BCS ≥ 3 had better pregnancy rate regardless of breed type and province. In conclusion, village cows can be synchronized successfully and inseminated with frozen-thawed semen. However, pregnancy rates are low in cows with lower body condition. Village Nguni type cows were not affected by body condition scoring as they had higher and similar pregnancy rate as those that had body condition of ≥3.

Abstract The objectives of the current study were to evaluate the estrous response and pregnancy rate following timed artificial insemination (TAI) with frozen-thawed semen in cows. The study was carried out in cows at different villages of KwaZulu-Natal (KZN; n = 160) and Limpopo provinces (L; n = 171). Cows were selected randomly as presented by the farmers, regardless of parity, age, breed and body weight following pregnancy diagnosis. The cows were grouped according to breed type and body condition score (BCS) on a scale of 1 - 5. Selected cows were inserted a controlled intravaginal drug release (CIDR®) and removed on day 8, followed by administration of prostaglandin. Heat was observed on day 9 with the aid of heat mount detectors (HMD) that were placed on the individual cow’s tail head. Cows on heat were then inseminated twice at 12 hours interval. Pregnancy diagnosis was performed by an ultra-sound scanner and rectal palpation 90 days after TAI. Data were analyzed using SAS 2006. Estrous responses were 100% in KZN and 99% in Limpopo. The lowest pregnancy rate was recorded in Brahman and Bonsmara type cows with BCS ≤ 2.5 regardless of province. Interestingly, Nguni type cows with BCS ≤ 2.5 had higher average pregnancy rate of 59.5% in Limpopo and 53.5% in KZN. However, cows with BCS ≥ 3 had better pregnancy rate regardless of breed type and province. In conclusion, village cows can be synchronized successfully and inseminated with frozen-thawed semen. However, pregnancy rates are low in cows with lower body condition. Village Nguni type cows were not affected by body condition scoring as they had higher and similar pregnancy rate as those that had body condition of ≥3.

Abstract The objectives of the current study were to evaluate the estrous response and pregnancy rate following timed artificial insemination (TAI) with frozen-thawed semen in cows. The study was carried out in cows at different villages of KwaZulu-Natal (KZN; n = 160) and Limpopo provinces (L; n = 171). Cows were selected randomly as presented by the farmers, regardless of parity, age, breed and body weight following pregnancy diagnosis. The cows were grouped according to breed type and body condition score (BCS) on a scale of 1 - 5. Selected cows were inserted a controlled intravaginal drug release (CIDR®) and removed on day 8, followed by administration of prostaglandin. Heat was observed on day 9 with the aid of heat mount detectors (HMD) that were placed on the individual cow’s tail head. Cows on heat were then inseminated twice at 12 hours interval. Pregnancy diagnosis was performed by an ultra-sound scanner and rectal palpation 90 days after TAI. Data were analyzed using SAS 2006. Estrous responses were 100% in KZN and 99% in Limpopo. The lowest pregnancy rate was recorded in Brahman and Bonsmara type cows with BCS ≤ 2.5 regardless of province. Interestingly, Nguni type cows with BCS ≤ 2.5 had higher average pregnancy rate of 59.5% in Limpopo and 53.5% in KZN. However, cows with BCS ≥ 3 had better pregnancy rate regardless of breed type and province. In conclusion, village cows can be synchronized successfully and inseminated with frozen-thawed semen. However, pregnancy rates are low in cows with lower body condition. Village Nguni type cows were not affected by body condition scoring as they had higher and similar pregnancy rate as those that had body condition of ≥3.

Understanding how the transmission of energy between the providers (such as nuclear power stations, renewable resources, or any type of supplying entity) and the consumers (such as factories, homes, or any type of demanding entity) depends on the structure of the inter-connections between them and on their dynamical be- haviour, is of paramount importance for the design of power-grid systems that are resilient to failures, e.g., failures due to structural modifications or energy fluctu- ations. In this thesis, we derive the implicit relationship between structure and behaviour that flow and power networks have, namely, the mathematical principles behind the transmission of energy in complex networks. From our novel derivations, we determine exact and approximate strategies to create self-controlled and stable systems (i.e., resilient to failures without the need for external controllers) that have an optimal (i.e., with less cost and power dissipation) and smart (i.e., allowing the decentralisation of large power-stations to smaller fluctuating renewable resources) energy distribution. Moreover, not only we achieve analytical solutions for problems that usually require a numerical analysis, but we also propose a change in the analy- sis view-point of complex systems, namely, systems composed of many dynamically interacting units forming a network. We show that in order to explain the emer- gent behaviour in these systems, instead of focusing on the network structure of the interactions, we should focus on the functional form of the interactions. In particu- lar, we derive a general framework to study the existence and stability of emergent collective behaviour in networks of interacting phase-oscillators, namely, the math- ematical principles behind the synchronisation in complex networks. The numerous breakthrough results in this thesis are expected to be of aid for engineers to design smarter and more resilient power-grid systems, as well as to scientists dealing with emergence of collective behaviour in complex systems.

Le but de cette thèse est d'étudier d'une façon expérimentale et théorique le comportement synchrone d'un groupe d'oscillateurs contrôlés par la lumière (LCOs). Ces LCOs sont très simples du point de vue électronique et ont la propriété d'imiter le comportement des lucioles puisqu'ils interagissent par des impulsions de lumière. En même temps, les LCOs sont une bonne approche pour étudier d'autres systèmes qui agissent comme des oscillateurs d'intégration et de tir car un LCO est un oscillateur de relaxation à deux échelles de temps : un long processus de charge alterné avec un très court processus de décharge. Une série d'expériences a été menée pour pouvoir comprendre le processus de synchronisation des LCOs. Nous avons trouvé que l'acquisition de la synchronisation est due aux effets de la perturbation à savoir: le raccourcissement de la charge et l'allongement de la décharge. Les mesures expérimentales ainsi que la physique liée aux LCOs nous ont permis de formuler un modèle qui a été utilisé pour trouver d'une façon analytique la courbe de réponse de phase (PRC) qui caractérise un LCO. Le modèle a ensuite été validé en comparant les résultats expérimentaux et théoriques. Le modèle reproduit même, le phénomène de bifurcation qui apparaît lorsque trois LCOs sont couplés et disposés en ligne : deux états stables différents apparaissent selon les conditions initiales. L'accord trouvé entre théorie et expérience nous permet d'utiliser le modèle pour étudier d'autres situations qui ne sont pas facilement abordables du point de vue expérimental. Nous avons étudié analytiquement deux LCOs identiques couplés. Même pour ce cas idéal, nous étions obligés de faire des simplifications pour pouvoir trouver des solutions exactes. On a trouvé pour ce système deux états possibles qui dépendent des conditions initiales, la synchronisation (stable) et l'anti-synchronisation (instable). Nous avons également montré que le temps de synchronisation augmente avec la distance entre LCOs. La construction des langues d'Arnold (régions de synchronisation) nous a permis de distinguer des régions de synchronisation pure d'ordre n:m et des régions de superposition synchronisation--modulation. Nous avons travaillé numériquement avec des systèmes de LCOs affectés de bruits uniforme et Gaussien. Le comportement synchrone de ce système a été caractérisé en utilisant des paramètres statistiques simples tels que la moyenne de la différence de phase linéaire et la variance de la différence de phase cyclique. Nous avons démontré que le bruit, bien qu'il puisse perturber la synchronisation, peut aussi la favoriser entre deux LCOs qui ne se synchroniseraient pas en conditions normales, surtout quand le bruit est Gaussien et que les variances du bruit ne sont pas égales. Nous avons étudié en termes statistiques la synchronisation de LCOs couplés localement et arrangés en ligne, en anneau et en réseau. Nous avons montré que la synchronisation totale se produit plus facilement pour des LCOs disposés en anneau. Concernant le temps de synchronisation, il est imprédictible. Les résultats analytiques et numériques suggèrent que la synchronisation totale est le phénomène le plus probable quand le nombre d'oscillateurs n'est pas très grand. Finalement, nous avons étudié des LCOs statiques et mobiles couplés globalement. Dans les deux cas, nous avons trouvé que la synchronisation est moins probable quand le nombre d'oscillateurs augmente. Pour la condition statique, en considérant un couplage du type champ moyen, nous avons observé que le temps de synchronisation diminue avec le nombre de LCOs. Cependant, pour la situation plus réaliste dans laquelle l'interaction entre LCOs dépend de la distance les séparant, le temps de synchronisation devient à nouveau imprédictible. Enfin, nous avons étudié l'influence de la mobilité sur la synchronisation, problème qui est important en biologie et en robotique. Notre système, de par ses caractéristiques et sa base expérimentale, est beaucoup plus proche de la réalité que ceux considérés d'habitude dans la littérature. Les résultats obtenus peuvent s'appliquer à des systèmes biologiques (lucioles, cellules cardiaques, neurones, …), mais également à la robotique, où la communication à longue portée par la lumière et l'émergence de patterns de synchronisation pourraient être très utiles dans le but d'effectuer des tâches spécifiques.

Synchronization means the aligning of the significant instants of one signal to the significant instants of another. In digital systems, where timing transfer between systems is required, synchronization is an important function. In this thesis new results on the performance and design of synchronization processes are presented.An inescapable consequence of the synchronization of external autonomous inputs in digital systems is the possibility of failure of digital devices used to capture the external signal. The anomalous behaviour of these devices is referred to as metastability. The most commonly used approach to controlling the problem of metastability is the use of synchronizers. A synchronizer can be designed to reduce the probability of metastable: failure but cannot eliminate it altogether. New high performance synchronizer designs are presented and analysed in this thesis.Another consequence of synchronization is the resulting disturbance of the significant epochs of timing signals. This disturbance is referred to as jitter. The characterization of jitter produced in synchronization processes is important in the design of digital systems. In this thesis, jitter characteristics are derived for two important applications that arise in digital communications systems. The characterization provides new insight into the dependence of the jitter on system parameters.

Orthogonal frequency-division multiplexing (OFDM) has been employed in several current and future 4-th generation (4G) wireless standards. Frequency offsets in OFDM introduce intercarrier interference (ICI). Channel estimations are also required. This thesis focuses on the channel and frequency offset estimation for OFDM-based systems. For cooperative-relay OFDM with frequency offsets, where inter-relay interference (IRI) exists, channel estimation is developed. Optimal pilot designs are proposed by minimizing the IRI in the mean square error (MSE) of the least square (LS) channel estimation. The impact of frequency offset on the channel estimation accuracy is derived. The pairwise error probability (PEP) with both the frequency offset and channel estimation errors is evaluated. The power allocation is discussed. For multiple-input multiple-output (MIMO) OFDM systems, channel and frequency offset estimation errors are investigated. The signal-to-interference-and-noise ratio (SINR) is first analyzed given channel and frequency offset estimation errors. The bit error rate (BER) is then approximated for multiple-antenna reception with maximal ratio combing (MRC) and equal gain combining (EGC). For orthogonal frequency-division multiplexing access (OFDMA) systems, the variance of the frequency offset estimation is derived as a function of SINR and signal-to- noise ratio (SNR). This variance information is exploited to improve the accuracy of frequency offset estimators. A successive interference cancellation (SIC)-based frequency offset estimator is also developed. The accuracy of frequency offset estimation of the OFDMA uplink can also be improved by using the cooperative relaying. Both conventional amplify-and-forward (AF) relays and new decode-and-compensate-and-forward (DcF) relays are studied. The frequency offset estimate is derived from combining different link estimates. In addition, when CSI is available, a scheme is proposed to adaptively switch between the cooperative and conventional (no relaying) transmissions to optimize the frequency offset estimation. / Wireless Communications

Thesis (Ph. D.)--University of Chicago, Dept. of Computer Science, March 1999. / Includes bibliographical references. Also available on the Internet.

This dissertation investigates the different organizational structures of paratransit services that cover large regions. A paratransit service is demand-responsive, shared-ride transit service using vans or small buses. It is characterized by the use of vehicles that do not operate on a fixed route or a fixed schedule. The paratransit route and schedule are arranged from a user-specified origin to a user-specified destination, and at a user-specified time. To retain productivity by focusing on shorter trips within a denser area, some larger systems have outsourced operations to more than one contractor, with each contractor responsible for the service zone to which their vehicles have been assigned. This service design is called a "zonal structure" or a "zoning approach." The zoning with transfer system coordinates vehicles' schedules at various transfer locations. The schedule coordination of inter-zonal mechanisms of transportation likely reduces trip costs by increasing the ridesharing rate and lowering the number of empty return miles. This study first presents the exact formulation for a coordinated decentralized paratransit system in order to compare its productivity and service quality with independent decentralized and centralized strategies. The formulation is then proven to work correctly, and the results of the computational experiments of small scale instances are shown to demonstrate that the proposed coordinated system is superior to independent decentralized systems in terms of passenger miles per vehicle revenue mile. In the second section, this study develops an insertion-based heuristic method in order to compare the performances of different operational designs when applied to a large-scale system. In an experiment utilizing Houston's demand-responsive service data, we compare the productivity and service levels among three organizational structures: zoning with transfer, zoning without transfer, and no-zoning designs. The results indicate that zoning with transfer can provide significant benefits to paratransit operations that manage zoning structure; however, the no-zoning strategy used by Houston METRO (a relatively low-density region) performs better on average in terms of efficiency. This study concludes that the zoning with transfer method can be proven to be a productive organizational structure.

In this paper, there are two major contents about OFDM synchronization issue in wireless communication. The first of all, a joint MLE and MMSE synchronization scheme is proposed for OFDM timing and frequency offset. Secondly, a novel pilot-aided inter-carrier interference (ICI) self-cancellation scheme is proposed for use in orthogonal frequency division multiplexing (OFDM) systems. The proposed scheme maps both modulated data symbols and pre-defined pilot symbols onto non-neighboring sub-carriers with weighting coefficients of +1 and -1. With the aid of pilot symbols, a more accurate estimation of frequency offsets can be obtained, and the ICI self-cancellation demodulation can be operated properly.