Numerical Modelling of Particle Transport in Reservoirs Due to Diurnal Temperature Variations

This thesis is concerned with particle transport in a reservoir model subject to periodic thermal forcing at the water surface. A commercial Computational Fluid Dynamics (CFD) code coupled with a Discrete Phase Model (DPM) is adopted to examine particle motions under various conditions. The following investigations have been carried out: Firstly, a previously reported concurrent Particle Image Thermometry and Particle Image Velocimetry (PIT/PIV) experiment has been numerically reproduced. Both qualitative and quantitative agreements are achieved between the present numerical simulation and the experiment. It is found in the parametric study that the Grashof number plays an important role in determining the onset time for the instability, the time duration of the unstable phase, and the time lag of the flow response to the switch of the thermal forcing. Secondly, the numerical model is adopted to investigate particle dispersion in the reservoir in a pseudo real-life scenario in which nutrient particles are injected from the sidearm of the reservoir. Both of the qualitative and quantitative studies have confirmed that natural convection has an indispensable role to play in terms of the pollutant transport in reservoirs. A case study based on an event of algal bloom with potentially severe effects on the water quality in Lake Burragorang in Sydney has been discussed. Finally, the numerical model has been extended to include particle collision and augmentation, and a preliminary study has been carried out to examine the effect of particle collision on the transport of particles in the water body. The results obtained with the inclusion of a particle collision model are compared with those obtained using a non-colliding particle model. It is revealed that, whilst the particle collision model may have a significant effect on the particle size distribution, depending on the initial particle concentration, its impact on the particle mass distribution is insignificant

Cross-layer energy-efficient schemes for multimedia content delivery in heterogeneous wireless networks

The wireless communication technology has been developed focusing on fulfilling the demand in various parts of human life. In many real-life cases, this demand directs to most types of commonly-used rich-media applications which – with diverse traffic patterns - often require high quality levels on the devices of wireless network users. Deliveries of applications with different patterns are accomplished using heterogeneous wireless networks using multiple types of wireless network structure simultaneously. Meanwhile, content deliveries with assuring quality involve increased energy consumption on wireless network devices and highly challenge their limited power resources. As a result, many efforts have been invested aiming at high-quality and energy-efficient rich-media content deliveries in the past years. The research work presented in the thesis focuses on developing energy-aware content delivery schemes in heterogeneous wireless networks. This thesis has four major contributions outlined below: 1. An energy-aware mesh router duty cycle management scheme (AOC-MAC) for high-quality video deliveries over wireless mesh networks. AOC-MAC manages the sleep-periods of mesh devices based on link-state communication condition, reducing their energy consumption by extending their sleep-periods. 2. An energy efficient routing algorithm (E-Mesh) for high-quality video deliveries over wireless mesh networks. E-Mesh evolves an innovative energy-aware OLSR-based routing algorithm by taking energy consumption, router position and network load into consideration. 3. An energy-aware multi-flow-based traffic load balancing scheme (eMTCP) for multi-path content delivery over heterogeneous wireless networks. The scheme makes use of the MPTCP protocol at the upper transport layer of network, allowing data streams to be delivered across multiple consequent paths. Meanwhile, this benefit of MPTCP is also balanced with energy consumption awareness by partially off-loading traffic from the paths with higher energy cost to others. 4. A MPTCP-based traffic-characteristic-aware load balancing mechanism (eMTCP-BT) for heterogeneous wireless networks. In eMTCP-BT, mobile applications are categorized according to burstiness level. eMTCP-BT increases the energy efficiency of the application content deliveries by performing a MDP-based distribution of traffic delivery via the available wireless network interfaces and paths based on the traffic burstiness level

User quality of experience of mulsemedia applications

User Quality of Experience (QoE) is of fundamental importance in multimedia applications and has been extensively studied for decades. However, user QoE in the context of the emerging multiple-sensorial media (mulsemedia) services, which involve different media components than the traditional multimedia applications, have not been comprehensively studied. This article presents the results of subjective tests which have investigated user perception of mulsemedia content. In particular, the impact of intensity of certain mulsemedia components including haptic and airflow on user-perceived experience are studied. Results demonstrate that by making use of mulsemedia the overall user enjoyment levels increased by up to 77%

5-{(2S,3R,4S,5S,6R)-3,4-Dihydr­oxy-6-hydroxy­meth­yl-3-[(2S,3R,4R,5R,6S)-3,4,5-trihydr­oxy-6-methyl­tetra­hydro­pyran-2-yloxy]tetra­hydro­pyran-2-yloxy}­-7-hydr­oxy-2-(4-hydroxy­phen­yl)chromen-4-one monohydrate

In the title compound, C27H30O14·H2O, the hydroxy­phenyl ring makes a dihedral angle of 20.05 (11)° with the chromenone ring system. The crystal structure is stabilized by intra- and inter­molecular O—H⋯O hydrogen bonds. The absolute configuration was assigned on the basis of an analagous structure

Bifurcation of Arabidopsis NLR Immune Signaling via Ca2+-Dependent Protein Kinases

Nucleotide-binding domain leucine-rich repeat (NLR) protein complexes sense infections and trigger robust immune responses in plants and humans. Activation of plant NLR resistance (R) proteins by pathogen effectors launches convergent immune responses, including programmed cell death (PCD), reactive oxygen species (ROS) production and transcriptional reprogramming with elusive mechanisms. Functional genomic and biochemical genetic screens identified six closely related Arabidopsis Ca2+-dependent protein kinases (CPKs) in mediating bifurcate immune responses activated by NLR proteins, RPS2 and RPM1. The dynamics of differential CPK1/2 activation by pathogen effectors controls the onset of cell death. Sustained CPK4/5/6/11 activation directly phosphorylates a specific subgroup of WRKY transcription factors, WRKY8/28/48, to synergistically regulate transcriptional reprogramming crucial for NLR-dependent restriction of pathogen growth, whereas CPK1/2/4/11 phosphorylate plasma membrane-resident NADPH oxidases for ROS production. Our studies delineate bifurcation of complex signaling mechanisms downstream of NLR immune sensors mediated by the myriad action of CPKs with distinct substrate specificity and subcellular dynamics

A Permeable Cuticle Is Associated with the Release of Reactive Oxygen Species and Induction of Innate Immunity

Wounded leaves of Arabidopsis thaliana show transient immunity to Botrytis cinerea, the causal agent of grey mould. Using a fluorescent probe, histological staining and a luminol assay, we now show that reactive oxygen species (ROS), including H2O2 and O2−, are produced within minutes after wounding. ROS are formed in the absence of the enzymes Atrboh D and F and can be prevented by diphenylene iodonium (DPI) or catalase. H2O2 was shown to protect plants upon exogenous application. ROS accumulation and resistance to B. cinerea were abolished when wounded leaves were incubated under dry conditions, an effect that was found to depend on abscisic acid (ABA). Accordingly, ABA biosynthesis mutants (aba2 and aba3) were still fully resistant under dry conditions even without wounding. Under dry conditions, wounded plants contained higher ABA levels and displayed enhanced expression of ABA-dependent and ABA-reporter genes. Mutants impaired in cutin synthesis such as bdg and lacs2.3 are already known to display a high level of resistance to B. cinerea and were found to produce ROS even when leaves were not wounded. An increased permeability of the cuticle and enhanced ROS production were detected in aba2 and aba3 mutants as described for bdg and lacs2.3. Moreover, leaf surfaces treated with cutinase produced ROS and became more protected to B. cinerea. Thus, increased permeability of the cuticle is strongly linked with ROS formation and resistance to B. cinerea. The amount of oxalic acid, an inhibitor of ROS secreted by B. cinerea could be reduced using plants over expressing a fungal oxalate decarboxylase of Trametes versicolor. Infection of such plants resulted in a faster ROS accumulation and resistance to B. cinerea than that observed in untransformed controls, demonstrating the importance of fungal suppression of ROS formation by oxalic acid. Thus, changes in the diffusive properties of the cuticle are linked with the induction ROS and attending innate defenses