Aspects of common hippopotamus (Hippopotamus amphibius) behavioural ecology and their consequences in managed systems in South Africa.

Doctoral Degree. University of KwaZulu-Natal, Pietermaritzburg.Abstract available in PDF

JOINT KINEMATIC ASYMMETRY BASED ON SPATIOTEMPORAL PATTERN DEVIATION DURING AN INCREMENTAL TEST IN HIGH LEVEL CYCLING

The aim of this study was to use two asymmetry indexes from a kinematical point of view in professional cyclists during an incremental test to exhaustion. Twelve professional cyclists were evaluated during the French Cycling Federation’s protocol. Based on motion capture, asymmetry analysis was addressed by means of cross-correlation technique and a normalized symmetry index (NSI). Results pointed out that NSI could vary up to 18% throughout the pedaling cycle, with different behavior between upward and downward pedaling phases. Both methods exhibited low values of asymmetry especially for flexion/extension, but higher asymmetry values for other DOF. This study shows the complementarity of both NSI and cross-correlation methods. It enables to continuously evaluate changes during the crank cycle associated to skeletal movement

A simple all-optical format transparent time and wavelength demultiplexing technique for WDM & Orthogonal-TDM Nyquist channels

A novel and simple non-coherent method to demultiplex WDM and orthogonal TDM Nyquist signal is presented. Using intensity modulators and filter, demultiplexing from a 3x8x10 = 240 Gb/s signal down to 10 Gb/s is demonstrated

Wideband All-Optical 3R WDM Regeneration Based on Dual-Pump Parametric Amplifier

Simultaneous all-optical 3R regeneration of WDM channels is demonstrated, based on dual-pump parametric amplification with sinusoidal modulated pumps. We observe receiver sensitivity improvement better than 1.5dB for five WDM channels modulated with 10Gb/s NRZOOK data

Experimental investigation of pulse generation with one-pump fiber optical parametric amplification

In a recent study, the theory of pulse generation with fiber optical parametric amplification using sinusoidal (clock) intensity modulated pump was revisited [1]. This work showed that the pulses generated through such parametric interaction exhibit a shape which depends on the signal detuning with respect to the pump position (i.e. linear phase mismatch). A near Gaussian shape can only be achieved over a small region of the gain spectrum, close to the maximum gain location. Towards the extremities of the gain spectrum, the generated pulses take a near Sinc shape which can have many potential applications such as for all-optical Nyquist limited transmitters and/or receivers. In this paper we experimentally verify the theory at repetition rates up to 40 GHz. We also discuss the impact of noise, pump saturation and walk-off on the generated pulses

Wideband Uniform Generation of Shape-Adjustable Pulses in Two-Pump Fiber Optic Parametric Amplifier

A tunable, stable pulse generation technique based on two-pump fiber optic parametric amplification is theoretically analyzed and experimentally demonstrated to generate uniform near-Gaussian pulses over 32 nm. It is shown that pulse shape can also be tuned and that a specific phase matching case enables Nyquist pulse generation over a wide bandwidth

Broadband Uniform Wavelength Conversion and Time Compression of WDM Channels

A scheme based on 2-pump OPA is proposed for uniform wavelength conversion and optimized compression. We show 4.7-fold compression over 32 nm range resulting in Gaussian pulses from sinusoidal modulation and enabling simultaneous compression of WDM channels for granularity adaptation

Sensitive and Accurate Dispersion Map Extraction of HNLFs by Frequency Tuning of a Degenerate FWM

A sensitive and accurate method for dispersion map extraction along an arbitrarily profiled highly nonlinear fiber (HNLF) is proposed. High sensitivity is achieved by positioning the wavelength of a signal at the band edge of the modulation instability (MI) spectrum generated by an intense degenerate four wave mixing (FWM) pump. In doing so, the to-be-extracted dispersion fluctuations leave a more drastic effect on the FWM-generated power since they either inflate or deflate theMI spectrum. The accuracy of the method is increased by monitoring the distribution of power along the fiber. Once the power distribution is measured along the fiber, dispersion map of the HNLF is extracted using an appropriate inverse algorithm, which reconstructs the dispersion with a highlevel ofaccuracy.

Bandwidth and repetition rate programmable Nyquist sinc-shaped pulse train source based on intensity modulators and four-wave mixing

We propose and experimentally demonstrate an all-optical Nyquist sinc-shaped pulse train source based on intensity modulation and four-wave mixing. The proposed scheme allows for the tunability of the bandwidth and the full flexibility of the repetition rate in the limit of the electronic bandwidth of the modulators used through the flexible synthesis of rectangular frequency combs. Bandwidth up to 360 GHz at 40 GHz rate and up to 45 frequency lines at 5 GHz rate are demonstrated with 40 GHz modulators. (C) 2014 Optical Society of Americ

Wideband generation of pulses in dual-pump optical parametric amplifier: theory and experiment

The generation of pulses in dual-pump fiber optical parametric amplifier is investigated. Theoretically, it is shown that in an analogical manner to pulse generation in single-pump fiber optical parametric amplifiers, the generated pulse shape depends on the linear phase mismatch between the interacting waves. However the dual-pump architecture allows for the bounding of the phase mismatch over a wide bandwidth. This feature permits the generation of uniform pulses over a wide bandwidth, contrary to the single-pump architecture. Using the developed theory, a pulse source with uniform pulses at 5 GHz repetition rate and duty cycle of 0.265 over 40 nm is demonstrated