When energy relaxation between electrons and the lattice is slow, an elevated electronic temperature different from that of the lattice persists. In this regime, hot charge carriers control the energy transport in a material. In this thesis, I show how hot carriers can dominate graphene's response enabling it to exhibit novel properties. First, I examine how light is converted to electrical currents in graphene and show that hot carriers play an integral role in this multi-stage process. I show that photocurrent in graphene p-n junctions is dominated by a Photo-thermoelectric effect in which a light-induced elevated hot carrier temperature drives a thermoelectric current. Furthermore, I show that the generation and cooling of hot carriers in graphene during photoexcitation proceeds in an unusual way. In the former, carrier-carrier scattering dominates the initial photoexcitation cascade enabling efficient hot carrier generation. In the latter, a new cooling mechanism - disorder-assisted scattering (supercollisions) - dominates electron-lattice cooling over a wide range of temperatures (including room temperature). Second, I examine the transport characteristics of double layer graphene heterostructures (specifically, G/h-BN/G heterostructures). I show that Coulomb coupling results in vertical (out-of-plane) energy transfer between electrons in proximal (but electrically insulated) graphene layers. This couples lateral (in-plane) charge and energy transport of electrons in the two layers to give rise to a new energy-driven Coulomb drag (inter-layer transresistance) that dominates when the two layers are at charge neutrality. Third, I examine energy transport in charge neutral graphene. I show that the combination of fast carrier-carrier scattering, high electronic quality, and slow electron-lattice cooling (hot carriers) gives rise to a regime of ballistic heat transport. This manifest as electronic energy waves with velocity on the order of graphene's Fermi velocity. The new phenomena enabled by hot carriers and the ideas/approaches described in this thesis provide a basis with which to exploit hot carrier effects in graphene and opens new vistas for controlling and harnessing energy flows on the nanoscale. / Engineering and Applied Sciences

New survey technologies are able to provide detailed data on the form and topography of riverbeds. With this increased data resolution, the required computational time rather than data availability has become the limiting factor for river models. Detailed bathymetric data can be used to provide better empirical representation of drag and roughness at fine scales, allowing a priori selection of roughness using known physics rather than a posteriori calibration. However, we do not have sufficient guidance or understanding from the literature to represent known heterogeneities smaller than our practical grid scale. The problem is what to do with known subgrid-scale bathymetric features and roughness when our models must use a coarser computational grid. In this project, we simplify this complex problem to analyzing flow in a simple open channel with a single patch of relatively high roughness against an otherwise uniform background of low roughness. We model this open channel with a two-dimensional, depth-averaged river model. By running multiple simulations using different grid sizes we gain insight into how the relationship between the grid cell size and the patch size affects the appropriate physical selection of roughness parameter. As the primary focus, the present work proposes and investigates several methods for upscaling known fine-scale drag coefficient data to a coarser grid resolution for a model. For the tested conditions, it appears that a simple area-weighted linear average is simple to apply and creates a flow field very similar to the best results achieved by calibration. As a secondary issue, the present work examines grid-dependent behaviors when using model calibration. Although recalibration of models for different grid scales is a common practice among modelers, we could find relatively little documentation or analysis. In our work, we examine both single-cell calibration (i.e. changing roughness in only the cell containing the rough patch) and multiple-grid cell calibration involving neighbor cells. With either method, improving calibration required multiple model simulations and comparative analysis for each tested grid size and was inefficient compared to the upscaling approach. As expected, the calibration at a given grid size was always inappropriate for a different grid size. / text

The purpose of this report is to investigate teachers views of whether pupils with Asperger Syndrome, autistic symptoms or ADHD shall go in ordinary classes or special groups. The study tells you about what difficulties these pupils often have, what adjustments they need in their schoolsituation and the positive and negative effects of joining a special group. A teacher for special needs, two teachers in special groups and two teachers in ordinary classes have been intervjued and earlier made researches have been studied. The conclusions of this study are that the decision of whether a pupil shall go in a normal class or a special group must be made individually. Most pupils who are capable to profit from the training in a normal class and pass their examination, shall go in a normal class. The greater part of the recommended adjustments are possible to do in a normal class. But it requires more resourses and teachers with better knowledges about theese handicaps. / Syftet med det här arbetet är att undersöka pedagogers syn på huruvida elever med Aspergers syndrom, autistiska drag eller ADHD ska gå i vanliga klasser eller i särskilda undervisningsgrupper. I studien beskrivs de svårigheter dessa elever ofta har, vilka anpassningar de behöver samt de för- respektive nackdelar som finns med särskild undervisningsgrupp. En specialpedagog, två lärare i särskilda undervisningsgrupper samt två lärare i vanliga klasser har intervjuats och texter med tidigare gjord forskning har studerats. Slutsatserna av undersökningen är att beslutet om huruvida eleven ska inkluderas i vanlig klass eller gå i särskild undervisningsgrupp måste avgöras noggrant från fall till fall. De elever som klarar att tillgodogöra sig undervisningen och nå godkända betyg i vanlig klass bör gå i vanlig klass. Merparten av de anpassningar som rekommenderas går att göra i vanlig klass. Det krävs dock att kompetensen hos lärarna höjs och att det skjuts till mer resurser.

This dissertation features the stories of drag king performers. Through life story interviews coupled with participant observations, and informed by gender performance, poststructuralist, and psychoanalytic theories, this project examines the ways in which drag performers construct, take up and perform multiple subjectivities and how they benefit from multiple knowledges in their learnings and unlearnings. Through an examination of the creation and circulation of these drag king pedagogies, I suggest ways in which drag performers create and sustain gendered knowledge, while navigating difference and working with multiple discourses of identity, oppression, and power in a socially and economically diverse city. Participants’ perceptions of their gender identities point to the ways in which identity categories are insufficient. Each participant uses an existing identity label (e.g., transgender, tranny, boi) or a combination of existing labels, to understand their gender identities, even as their narratives point to the failures of fixed categories. It is my contention that the narratives of these particular performers highlight the multiplicity of all selves, and the ways in which all learnings and unlearnings are fragmented. Thus, drag king narratives have significant pedagogical value in examining the relationships between subjectivities and knowledge.

Contributions to two missions are presented. The first is a demonstration mission called CanX-7 that uses a 4 square metre drag sail to de-orbit a 3.5 kg satellite. In order to estimate the effectiveness of the drag sail, a novel method is developed that takes into account the time-varying nature of the projected drag area. The Space Flight Laboratory designed drag sail is shown to be sufficient to de-orbit the CanX-7 spacecraft within the 25 year requirement. The Antarctic Broadband demonstrator spacecraft is a 20 cm cubical nanosatellite that will demonstrate the feasibility of a Ka-band link between the research community in Antarctica and stakeholders in Australia. In support of this mission, a passive thermal control subsystem is designed that will keep all the components within their operational temperature limits at all times throughout the mission.

No description available.

Contributions to two missions are presented. The first is a demonstration mission called CanX-7 that uses a 4 square metre drag sail to de-orbit a 3.5 kg satellite. In order to estimate the effectiveness of the drag sail, a novel method is developed that takes into account the time-varying nature of the projected drag area. The Space Flight Laboratory designed drag sail is shown to be sufficient to de-orbit the CanX-7 spacecraft within the 25 year requirement. The Antarctic Broadband demonstrator spacecraft is a 20 cm cubical nanosatellite that will demonstrate the feasibility of a Ka-band link between the research community in Antarctica and stakeholders in Australia. In support of this mission, a passive thermal control subsystem is designed that will keep all the components within their operational temperature limits at all times throughout the mission.

No description available.

lthough extensive research work has been carried out on the drag reduction behavior of polymers and surfactants alone, little progress has been made on the synergistic effects of combined polymers and surfactants. A number of studies have demonstrated that certain types of polymers and surfactants interact with each other to form surfactant-polymer complexes. The formation of such complexes can cause changes in the solution properties and may result in better drag reduction characteristics as compared with pure additives. A series of drag-reducing surfactants and polymers were screened for the synergistic studies. The following two widely used polymeric drag reducing agents (DRA) were chosen: a copolymer of acrylamide and sodium acrylate (referred to as PAM) and polyethylene oxide (PEO). Among the different types of surfactants screened, a cationic surfactant octadecyltrimethylammonium chloride (OTAC) and an anionic surfactant Sodium dodecyl sulfate (SDS) were selected for the synergistic study. In the case of the cationic surfactant OTAC, sodium salicylate (NaSal) was used as a counterion. No counterion was used with anionic surfactant SDS. The physical properties such as viscosity, surface tension and electrical conductivity were measured in order to detect any interaction between the polymer and the surfactant. The drag reduction (DR) ability of both pure and mixed additives was investigated in a pipeline flow loop. The effects of different parameters such as additive concentration, type of water (deionized (DI) or tap), temperature, tube diameter, and mechanical degradation were investigated. The addition of OTAC to PAM solution has a significant effect on the properties of the system. The critical micelle concentration (CMC) of the mixed surfactant-polymer system is found to be different from that of the surfactant alone. The anionic PAM chains collapse upon the addition of cationic OTAC and a substantial decrease in the viscosity occurs. The pipeline flow behaviour of PAM/OTAC mixtures is found to be consistent with the bench scale results. The drag reduction ability of PAM is reduced upon the addition of OTAC. At low concentrations of PAM, the effect of OTAC on the drag reduction behavior is more pronounced. The drag reduction behavior of polymer solutions is strongly influenced by the nature of water (de-ionized or tap). The addition of OTAC to PEO solution exhibited a week interaction based on the viscosity and surface tension measurements. However, the pipeline results showed a considerable synergistic effect, that is, the mixed system gave a significantly higher drag reduction (lower friction factors) as compared with the pure additives (pure polymer or pure surfactant). The synergistic effect in the mixed system was stronger at low polymer concentrations and high surfactant concentrations. Also the resistance against mechanical degradation of the additive was improved upon the addition of OTAC to PEO. The mixed PEO/SDS system exhibited a strong interaction between the polymers (PEO) and the surfactant (SDS), Using electrical conductivity and surface tension measurements, the critical aggregation concentration (CAC) and the polymer saturation point (PSP) were determined. As the PEO concentration is increased, the CAC decreases and the PSP increase. The addition of SDS to the PEO solution exhibits a remarkable increase in the relative viscosity compared to the pure PEO solution. This increase is attributed to the changes in the hydrodynamic radius of the polymer coil. The pipeline flow exhibited a considerable increase in DR for the mixed system as compared to the pure PEO solution. The addition of surfactant always improves the extent of DR up to the PSP. Also the mixed PEO/ SDS system shows better resistance against shear degradation of the additive.

This study investigates whether the flood regime in a catchment is sensitive to the condition of riparian vegetation along the river network. The research is based on a comprehensive assessment and synthesis of field and laboratory measurements of vegetation flow resistance. A new numerical model is developed to estimate the roughness characteristics of multi-species riparian assemblages at a cross-section. Reach-scale and catchment-scale flood routing models are then applied to estimate the impact of vegetation on flood characteristics at successively larger scales. The investigation reveals that when riparian vegetation is removed at catchment-scale, peak stage declines as channel capacity increases but is also increased as the upstream catchment responds more rapidly to rain. In fact, the two competing impacts tend to cancel out leaving flood peak stage relatively insensitive to riparian condition. However, the overbank duration of a flood and flow speeds (including wave celerity) were both found to be sensitive to vegetation condition; respectively increasing and decreasing with density of vegetation. The first stage of this research examines the magnitude of the vegetation contribution to overall channel roughness, and established a means to predict it. The features of the flow resistance generated by six plant types (mature trees; grasses; aquatic plants; flexible saplings; and large woody debris) were distilled from a comprehensive review of over 160 existing publications (Chapter 2).