Please read the abstract in the section 00front of this document / Dissertation (MSc)--University of Pretoria, 2003. / Geology / Unrestricted

For fatigue design of welded hollow structural sections connections, the “hot spot stress method” in CIDECT Design Guide 8 is widely used. This method forms the basis of various national and international design standards. This thesis sought to address some contemporary design issues where the existing approaches cannot be directly applied. Modified design approaches were proposed for various practical design details. For galvanizing of welded tubular steel trusses, sufficiently large holes to allow for quick filling, venting and drainage must be specified. These holes, quite often specified at the hot spot stress locations, will inevitably affect connection fatigue behaviour. In Chapter 1, six rectangular hollow section (RHS) connections were tested under branch axial loading. The stress concentration factors (SCFs) obtained from the experimental investigation were compared with those calculated using the formulae in CIDECT Design Guide 8. It was shown that the predictions based on the current formulae were unsafe. Hence, finite element (FE) models were developed and validated by comparison with the experimental data. A subsequent parametric study was conducted, including 192 FE models with different hole locations and non-dimensional parameters [branch-to-chord width (β), branch-to-chord thickness (τ), and chord slenderness (2γ) ratios]. SCF formulae for RHS connections with vent/drain holes at different locations were established based on the experimental and FE data. In Chapter 2, by modifying the 192 parametric models in Chapter 1, FE analysis was performed to examine the existing SCF formulae in CIDECT Design Guide 8 for RHS T-connections under branch in-plane bending. The parametric study showed that the existing SCF formulae can lead to unsafe predictions. Critical hot spot stress locations were thus identified. The effects of both branch in-plane bending and chord loading were studied. New design formulae that take the vent and drain holes into account were proposed. The design rules in CIDECT Design Guide 8 assumes sufficient chord continuity on both sides of connection. Therefore, the existing formulae cannot be directly applied to RHS-to-RHS connections situated near a truss/girder end. Chapter 3 sought to develop new approach for calculation of SCFs in such connections. 256 FE models of RHS-to-RHS X-connections, with varied chord end distance-to-width (e/b0) and non-dimensional parameters were modelled and analyzed. The analysis was performed under quasi-static axial compression force(s) applied to the branch(es) and validated by comparison of strain concentration factors (SNCFs) to SNCFs obtained from full-sized connection tests. For all 256 connections, SCFs were determined at five critical hot spots on the side of the connection near the open chord end. The SCFs were found to vary as a function of e/b0, 2γ and β. Existing formulae in CIDECT Design Guide 8 to predict SCFs in directly welded RHS-to-RHS axially loaded X-connections were shown to be conservative when applied to a connection near an open chord end. SCF reduction factors (ψ), and a parametric formula to estimate ψ based on e/b0, 2γ and β, were derived. For RHS-to-RHS connections situated near a truss/girder end, reinforcement using a chord-end cap plate is common; however, for fatigue design, formulae in current design guidelines [for calculation of SCFs] cater to: (i) unreinforced connections, with (ii) sufficient chord continuity beyond the connection on both sides. Chapter 4 sought to develop definitive design guidelines for such connections. The parametric models in Chapter 3 were modified to simulate such connections. Existing SCF formulae in CIDECT Design Guide 8 were shown to be inaccurate if applied to cap plate-reinforced end connections. SCF correction factors (ψ), and parametric formulae to estimate ψ based on e/b0, β, τ and 2γ, were derived. The same methodology was used in Chapter 5 to study the SCFs in square bird-beak (SBB) and diamond bird-beak (DBB) tubular steel X-connections situated at the end of a truss or girder. A comprehensive parametric study, including 256 SBB and 256 DBB connection models, covering wide ranges of chord end distance-to-width (e/b0) and non-dimensional parameters, was performed. Two sets of correction factor (ψ) formulae for consideration of the chord end distance effect were derived, for SBB and DBB X-connections, respectively. / Graduate

This essay intends to examine the phenomenon of virtual influencers on Instagram and contribute with a fundamental knowledge within a relatively unexplored field of research. By studying the comment sections of three virtual influencers with authenticity and parasocial relationships as the theoretical starting point the essay aims to contribute with insights about participation. The comment data is examined through a combined method of a quantitative and qualitative content analysis. The entirety of the material is coded quantitatively to map the main characteristics of the comments. Qualitative tools then enable a further and deeper analysis of the comments categorized as longer and they are coded a second time. The result of the two code schemes is presented using charts and tables. These describe the type of participation that occurred and the thematization and categorization of the longer comments. Examples that represent different attributes and angles of the categories and subcategories are broken down into components as a final step of the analysis.  The results of the study include signs of parasocial relationships in a variety of forms. Compliments, conversation starters and friendly questions are in some instances openly conscious of the fact that the influencer is not a real person, and some are not. Certain friendly comments strengthened the influencers’ authenticity, and a few questioned their actions with references to previously communicated preferences. Although there were a few participants who pointed at the influencers’ persona, most of the comments regarding authenticity revolved around their physical form or existence. Signs of hatred, fear and anger occurred in this fraction of the comments. / Denna studie ämnar undersöka deltagande riktat till fenomenet virtuella influencers och bidra med grundläggande kunskap inom ett relativt outforskat område. Genom att studera kommentarsfälten på tre virtuella influencers Instagramkonton med fokus på parasociala relationer och autenticitet ger studien en inblick i hur deltagandet ser ut när allt är på låtsas. Kommentarerna analyseras genom en kombination av kvantitativ och kvalitativ innehållsanalys. Det första steget är en kvantitativ kartläggning av samtliga kommentarer för att ge en övergripande bild av deltagandet. Vidare analyseras de längre kommentarerna djupare genom kvalitativa verktyg för att belysa tecken på parasociala relationer och föreställningar om autenticitet.  Resultaten visar tecken på parasociala relationer i ett flertal former. Komplimanger, inbjudningar till konversation och vänskapliga frågor kommuniceras från skribenter som i vissa fall uppvisar vetskap om att influencern är en fiktiv karaktär och i vissa fall inte. En del vänskapliga kommentarer stärker influencerns autenticitet och en del hänvisar till tidigare uttalanden och ifrågasätter kontoinnehavarna. Även om en del kommentarer gällande autenticitet rörde karaktärernas persona relaterade de flesta till deras fysiska (icke-)existens. Bland dessa kommentarer förekom tecken på hat, rädsla och ilska.

Objective: Background: Rare disease An epithelial inclusion cyst within a lymph node denotes a heterotopic phenomenon. Nodal epithelial inclusion cysts have been reported in a variety of anatomical locations including pelvic, abdominal, mediastinal, and axillary regions. While nodal melanocytic nevus (also known as nevus cell aggregates) is the most common heterotopic phenomena involving the axillary lymph nodes, the presence of benign epithelial inclusion cysts in axillary lymph nodes is a rare but well-reported finding. Such documentation is in part due to assessment of sentinel lymph nodes in breast cancer becoming standard of care. These epithelial inclusion cysts offer a diagnostic pitfall in evaluation of sentinel lymph node in the setting of breast carcinoma. They also complicate assessment of sentinel lymph node during intraoperative frozen sections analysis. Case Report: We report a case of co-existent of benign squamous-type and glandular-type epithelial inclusions cysts in 2 sentinel lymph nodes in a patient with grade III invasive ductal carcinoma involving the left breast. There have been at least 4 cases reported in literature in which benign epithelial inclusion cysts in sentinel lymph nodes were first mistakenly diagnosed as metastatic carcinoma both during intraoperative frozen section analysis and during review of permanent sections. The missed diagnosis could potentially occur intraoperatively during frozen section sentinel lymph node analysis secondarily due to lack of availability of the primary tumor for comparison and inability to use immunohistochemical stains. Conclusions: Pathologists should be aware of this pitfall especially in frozen section analysis of sentinel lymph node to avoid misdiagnosis and its associated potential grave consequences.

Six geomorphic study reaches were established in 2002 along a forested mountain stream (gradients range from 0.02 to 0.05) on Cal Poly's Swanton Pacific Ranch in Santa Cruz County, California. These study reaches are a component of paired and nested watershed studies in the approximately 500 hectare Little Creek watershed. The overall goal of this study was to monitor water quality and channel conditions before, during, and after a selective harvest of redwood. A selective harvest occurred in the North Fork of Little Creek in Summer 2008. In August 2009, approximately 90% of the Little Creek Watershed was burned in the Lockheed Fire. Channel change was evaluated by measuring ground profiles using traditional survey methods. Cross section and longitudinal profiles are surveyed annually every summer in the six study reaches. Change is assessed through evaluation of cross sections and longitudinal profiles, analysis of bed elevation and cross-sectional area change data, and analysis of residual pool characteristics and longitudinal profile variability. Changes in the channel during this time have been relatively small and are typically associated with movement or introduction of coarse woody debris to the stream channel. However, during the study period no large stream flow events occurred (return interval at the closest USGS gauging station does not exceed 5 years). Historically, large debris flow events have occurred in this watershed, with well documented events in 1955 and 1998. The survey data is an important tool for understanding change detection in channel characteristics before and after harvesting, and following fire disturbance.

No description available.

No / This paper presents the behaviour and design of axially loaded concrete filled stainless steel circular and square hollow sections. The experimental investigation was Conducted using different concrete cube strengths varied from 30 to 100 MPa. The column strengths and load-axial shortening curves were evaluated. The study is limited to cross-section capacity and has not been validated at member level. Comparisons of the tests results together with other available results from the literature have been made with existing design methods for composite carbon steel sections-Eurocode 4 and ACI. It was found that existing design guidance for carbon steel may generally be safely applied to concrete filled stainless steel tubes. though it tends to be over-conservative. A continuous strength method is proposed and it is found to provide the most accurate and consistent prediction of the axial capacity of the composite concrete filled stainless steel hollow sections due largely to the more precise assessment of the contribution of the stainless steel tube to the composite resistance.

<p> A research programme is presented to more fully understand the behaviour of Round Hollow Structural Sections subjected to inelastic strain reversals. An attempt is made to establish a preliminary guideline for choosing a reasonable value for the slenderness ratio (D/t) that qualifies the Round HSS for cyclic loading. </p> <p> An experimental programme on nine sections was performed to evaluate the loss in load capacity due to inelastic cyclic loading and to construct the load-deflection hysteresis loops. </p> <p> Three different limiting cyclic deflections were imposed to the smallest D/t section and a comparison was made between the performance of the tube in each case. </p> <p> Prasad's computer program was used to select the strain value at which local buckling will appear and to calculate the half buckle wave-length. The results were compared to the experimental results obtained by the author. </p> <p> A comparison is made between two Round HSS having different diameters and thicknesses but the same D/t ratio. </p> <p> A comparison is made between the behaviour of Round HSS and Square HSS subjected to the same cyclic loading programme. </p> <p> An attempt is made to suggest a reasonable curve relating the number of cycles to failure and the D/t ratio. </p> / Thesis / Master of Engineering (ME)

<p> A research programme is presented for assessing the capability of Hollow Structural Sections in Plastic Design. This investigation attempts to relate the flange slenderness and yield stress to the rotation capacity of Hollow Structural Sections subjected to both constant moment regions and to moment gradients. </p> <p> An experimental programme was performed on 31 different cross sections to evaluate the moment-curvature relationship which is of fundamental importance in Plastic Methods. The occurrence of local buckling for some sections in the compression flange and the consequent reduction in moment resistance is the critical factor which separates members into compact and non compact categories. </p> <p> The moment-curvature relations from tests are compared with analytical predictions. The plastic hinge rotations delivered by the present test sections are compared with the maximum practical requirements for plastically designed continuous beams. Theoretical elastic and inelastic buckling solutions of plate elements are also presented to relate to possible local buckling of the flats of square and rectangular hollow structural sections. </p> <p> Plate ratios of compression flanges are then selected for use in plastic design of hollow structural sections. Such a separation permits segregation into compact and non compact categories and can be used in working stress or elastic design methods. </p> / Thesis / Master of Engineering (ME)

<p> Trusses and Vierendeel girders are usually built from a single chord HSS "Hollow Structural Sections", but the largest HSS size as produced in Canada may limit its use for longer span applications. Therefore, the possibility of using double chord sections to enable the use of HSS for longer span trusses without the need for manufacturing new larger sections, presented itself. </p> <p> A new concept utilizing double chord square hollow sections in welded K-joints of Warren trusses is described. The experimental results of 29 tests are reported, including four connections types — standard, channel, bolted and back-to-back. The latter type comprised of gapped, overlapped and gapped with connecting stiffener plates. </p> <p> The results indicate that the standard type is an excellent joint in both strength and stiffness. The channel type is generally susceptible to twisting. It was found adequate only when a significant increase in chord thickness (≃ 50%) was employed. The bolted connection appears to hold promise when on-site assembly of large trusses is necessary. Its performance was further improved by connecting the chords with small tie bars. The back-to-back type needed to be reinforced or fully overlapped to develop full branch member strength. </p> <p> The double chord system of connection reveals itself to be much superior in strength to an equivalent single chord joint. </p> <p> The effects of eccentricity, branch member to chord angle, and chord preloading were investigated. Interaction formulae are presented for the standard and channel type joints which suffered from a chord failure at the connection. </p> <p> Results of four T-type connections using the double chord concept are also reported and were recently published in the ASCE (8). </p> / Thesis / Doctor of Philosophy (PhD)