Shallow marine environments from the Lower Cambrian period were very different to shallow marine environments of today. Tubes of what was thought to be silica recovered from a partly dolomitized carbonate sample collected form a site near Indian Springs, Nevada could help further understand the chemistry and characteristics of such environments. The aim of this study is to present a detailed morphological description of the tubular structures found in the rock sample as well as to give a description of the environment in which they were produced. This was achieved by first studying the samples with several different analytical techniques including Scanning Electron Microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDS) and subsequent evaluation of the obtained data. This resulted in the discovery that the tubular structures have a wall mainly consisting of non-detrital silica crystals. The crystals are arranged in string-like structures which overlap to form tube walls of varying thicknesses. The observed tubular structures are typically straight and ca. 0,23 to 0,25 mm long, but slightly curved and rare bifurcating tubes were also seen. The elemental mapping of a thin section of tubes showed that the wall-forming crystals consist mainly of silica (SiO2), however, small concentrations of calcium (Ca) were found inside many of the silica crystals leading to the conclusion that positive calcium ions may have acted as a seed for the silica crystals. A comparison of the tubular structures with other tubular fossils of the same geological time period is presented as well as a discussion of whether the specimens are of biological origin, and consequently a biosignature, as these could be used in future research when studying material from other planetary bodies. / Grunda marinmiljöer i nedre Kambrium var väldigt annorlunda från grunda marinmiljöer som finns idag. Små rör av vad som hypotiserades vara kiseloxid upptäckta i en dolomitiserad kalkstenstuff från Indian Springs, Nevada skulle kunna hjälpa att förstå kemin inblandad i bildandet av dessa samt bildningsmiljön i mer detalj. Syftet med detta projekt är att presentera en detaljerad morfologisk beskrivning av dessa rör samt försöka beskriv miljön i vilken de bildades. Undersökningen gjorde genom att först studera rören med olika mikroskoperingsmetoder inklusive ett optiskt mikroskop samt med ett svepelektronmikroskop (SEM), sedan analyserades proverna med Energidispersiv röntgenspektroskopi (EDS) för att detektera och kartera de grundämnena som fanns i rören. Resultaten av dessa metoder är att rören är cylindriska eller cigarrformade samt har en väggstruktur av kiseldioxidkristaller som sitter ihop som strängar av pärlor. Rören är huvudsakligen raka och har en längd på mellan 0,23 och 0,25mm, även böjda och förgrenade rör hat hittats, dock var mer sällsynta än de raka. Den kemiska analysen av ett tunnslip på några rör visade att de består till mestadels av kiseldioxid (SiO2) men koncentrationer av kalcium (Ca) hittades som indikerar att dessa kanske agerade som små frön för kiseldioxid att växa runt. En jämförelse av dessa rör med andra liknande fossilmed samma struktur och från samma tidsperiod är presenterad samt en diskussion kring rören som biosignatur och dess potentiella biologiskt ursprung samt användning i framtida forskning inom ämnet.

Stale bread contributes to the biggest volume of food waste in Sweden. Current method on recovering bread waste is by producing biogas or bioethanol. Despite advantages in the energy sector, the bread which still has relatively high quality could be recovered into new products with higher value, such as food for human consumption. Development of a product, termed ‘fungal cake’ by solid state fermentation on bread waste using Neurospora intermedia in small scale petri dishes have previously been successfully conducted. This study aims to scale up the production of fungal cake into bench scale production. Two systems using different bioreactors were used in this study. The first system operated in batch mode using a tray bioreactor, in which the effect of particle size, mixing, and bread loading were evaluated. The fermentation was conducted during 5 days. Bread crumb with a larger particle size of 2 mm resulted in similar outcomes as bread crumb with a smaller particle size of 0.5 mm in terms of CO2 evolution rate, cumulative CO2 production, starch, and protein content of the final product. However, larger particle size resulted in a more homogeneous growth of the fungus throughout the product, which is preferred. The presence of daily mixing had no significant effect compared to static condition for all measured variables. Thus, mixing could be introduced to promote product homogeneity. Likewise, bread loading had no significant effect on the measured variables, which implies that a higher productivity can be achieved using a higher bread loading. The second system operated in continuous mode using a newly developed continuous tubular bioreactor with product recycle. Two experiments, in which the residence time (48h and 24h) and recycle ratio (10/65 and 20/55) were conducted. Both experiments yielded product with stable starch and protein content, indicated by a stable CO2 evolution rate over time. The performance using continuous tubular bioreactor was compared to batch fermentation in tray bioreactor using the same ratio of inoculum and both system yielded product with the same starch and protein content. Successful operation in continuous bioreactor certainly improved the productivity of fungal cake production.

The stress and strength behavior of cylindrical tubular adhesive joints composed of dissimilar materials was explored. This was accomplished with the finite element method (FEM) and stress-based failure theories. Also, it was shown how a design of experiments (DOE) based method can be used to objectively organize the process of optimizing joint strength by using stress-based failure criteria. The finite element program used in this work was written in-house from scratch to implement the FEM for the purpose of solving both axisymmetric and three-dimensional linear elastic governing equations of static equilibrium. The formulation of the three-dimensional model is presented, and the required operations to arrive to the axisymmetric model are also presented. The axisymmetric model is two dimensional, capable of using four and eight node quadrilateral elements. However, only four node elements are used because a mesh of eight node elements requires more memory and increased mesh refinement. The three-dimensional model is capable of using eight and twenty node brick elements, but only eight node brick elements are used for the same reason. Both of the axisymmetric and three-dimensional models calculate the nodal displacements, strains, stress values for each material, and strength values for each material. The external static loads can be individually applied, or coupled together. The outputs seem to be most useful for interpretation when plotted through-the-thickness (TTT) and along-the-length (ATL) of the joint or tube. Outputs are valid only for materials that behave linearly elastic up to(or near) failure, and the stress-based failure criteria are used to define that limit. A small laboratory-sized joint was modeled to look at the theoretical stress and strength distributions plotted along-the-length of the joint at different radial locations. These stress and strength distributions can be correlated to the type of load being applied because of unique or prominent features seen in the stress and strength distributions. The load can be a uniform temperature change, axial load, torque load, internal and external pressure, and/or bending load. A variance in the stress or strength for different joint sizes and materials is not examined closely due to the many possible combinations of these parameters.

No description available.

The purpose of this research is to examine the behaviour of elliptical concrete-filled steel tubular stub columns under a combination of axial force and bending moment. Most of the research carried out to date involving concrete-filled steel sections has focussed on circular and rectangular tubes, with each shape exhibiting distinct behaviour. The degree of concrete confinement provided by the hollow section wall has been studied under pure compression but remains ambiguous for combined compressive and bending loads, with no current design provision for this loading combination. To explore the structural behaviour, laboratory tests were carried out using eight stub columns of two different tube wall thicknesses and applying axial compression under various eccentricities. Moment-rotation relationships were produced for each specimen to establish the influence of cross-section dimension and axis of bending on overall response. Full 3D finite element models were developed, comparing the effect of different material constitutive models, until good agreement was found. Finally, analytical interaction curves were generated assuming plastic behaviour and compared with the experimental and finite element results. Ground work provided from these tests paves the way for the development of future design guidelines on the member level.

This paper presents the details of an experimental investigation on the behaviour of axially loaded concrete-filled stainless steel elliptical hollow sections. The experimental investigation was conducted using normal and high strength concrete of 30 and 100 MPa. The current study is based on stub column tests and is therefore limited to cross-section capacity. Based on the equations proposed by the authors on concrete-filled stainless steel circular columns, a new set of equations for the stainless steel concrete-filled elliptical hollow sections were proposed. From the limited data currently available, the equation provides an accurate and consistent prediction of the axial capacity of the composite concrete-filled stainless steel elliptical hollow sections.

No description available.

Indiana University-Purdue University Indianapolis (IUPUI) / Crashworthiness design is gaining more importance in the automotive industry due to high competition and tight safety norms. Further there is a need for light weight structures in the automotive design. Structural optimization in last two decades have been widely explored to improve existing designs or conceive new designs with better crashworthiness and reduced mass. Although many gradient based and heuristic methods for topology and topometry based crashworthiness design are available these days, most of them result in stiff structures that are suitable only for a set of vehicle components in which maximizing the energy absorption or minimizing the intrusion is the main concern. However, there are some other components in a vehicle structure that should have characteristics of both stiffness and flexibility. Moreover, the load paths within the structure and potential buckle modes also play an important role in efficient functioning of such components. For example, the front bumper, side frame rails, steering column, and occupant protection devices like the knee bolster should all exhibit controlled deformation and collapse behavior. This investigation introduces a methodology to design dynamically crushed thin-walled tubular structures for crashworthiness applications. Due to their low cost, high energy absorption efficiency, and capacity to withstand long strokes, thin-walled tubular structures are extensively used in the automotive industry. Tubular structures subjected to impact loading may undergo three modes of deformation: progressive crushing/buckling, dynamic plastic buckling, and global bending or Euler-type buckling. Of these, progressive buckling is the most desirable mode of collapse because it leads to a desirable deformation characteristic, low peak reaction force, and higher energy absorption efficiency. Progressive buckling is generally observed under pure axial loading; however, during an actual crash event, tubular structures are often subjected to oblique impact loads in which Euler-type buckling is the dominating mode of deformation. This undesired behavior severely reduces the energy absorption capability of the tubular structure. The design methodology presented in this paper relies on the ability of a compliant mechanism to transfer displacement and/or force from an input to desired output port locations. The suitable output port locations are utilized to enforce desired buckle zones, mitigating the natural Euler-type buckling effect. The problem addressed in this investigation is to find the thickness distribution of a thin-walled structure and the output port locations that maximizes the energy absorption while maintaining the peak reaction force at a prescribed limit. The underlying design for thickness distribution follows a uniform mutual potential energy density under a dynamic impact event. Nonlinear explicit finite element code LS-DYNA is used to simulate tubular structures under crash loading. Biologically inspired hybrid cellular automaton (HCA) method is used to drive the design process. Results are demonstrated on long straight and S-rail tubes subject to oblique loading, achieving progressive crushing in most cases.

The main focus of our research was to compare changes in ion excretion in urine, osmolality, indicators of exercise-induced proteinuria and tubular markers before and after dynamic exercise on a bicycle ergometer. The test sample consisted of 7 healthy, physically active women aged 27.4 years ( σ = 3.82 ). For dynamic exercise we uniformly set parameters 65 % VO2max and duration of load in 50 minutes. We compared the laboratory results of urine samples taken just before the exercise with urinary samples that we have collected immediately after exercise. The results of our measurements showed a significant changes in exercise-induced urinary sodium ions, creatinine and phosphorus. Statistically insignificant changes excretion was found between markers: chlorine, urine, osmolality, and N-acetyl-beta- d-glucosaminidase. These markers, however, show a trend the significance. Statistically insignificant changes after exercise have shown excretion of urinary markers: potassium, gelatinase-associated lipocalin, neutrophil microalbuminuria and alpha-1-microglobulin. Tubular markers of kidney damage after exercise is not at the reference values, that would indicate the tubular kidney damage.

Os tubos API 5L X80, construídos com aços alta resistência e baixa liga, são especificados para a construção de dutos para transporte de petróleo e derivados sob alta pressão, com conseqüente redução no peso dos tubos. O processo mais empregado para a soldagem circunferencial de tubos em campo no Brasil é o processo com eletrodo revestido, tanto para o passe de raiz quanto para os passes de enchimento. Uma alternativa para o passe de raiz é o processo de soldagem MAG com Transferência Controlada (MAG-TC), enquanto que o enchimento pode ser feito com o processo de soldagem utilizando eletrodo tubular (AT), tanto o auto-protegido (AT-AP) como o com proteção gasosa (AT-PG). Esta combinação de processos (MAG-TC + AT) apresenta-se como um promissor substituto do processo de soldagem com eletrodo revestido, reunindo alta qualidade do metal de solda depositado e alta produtividade. O objetivo deste trabalho é estudar a soldabilidade do tubo API 5L X80 nacional, com 508 mm (20\") de diâmetro e 19 mm (3/4\") de espessura, comparando-se duas combinações de processos de soldagem circunferencial: MAG-TC + AT-PG e MAG-TC + AT-AP. A soldagem foi realizada com o arame ER80S-G no passe de raiz e processo MAG-TC com proteção de CO2. O enchimento foi feito com os arames E101T1-GM-H8 (com proteção gasosa) e E91T8-G (auto-protegido). Foram fixadas as temperaturas de pré-aquecimento (150 °C) e interpasse (250 °C) para ambas combinações de processos de soldagem. As juntas foram caracterizadas utilizando-se: análise química, saturação magnética, metalografia óptica e eletrônica de varredura e ensaios mecânicos: dureza Vickers, tração, dobramento, nick-break e ensaio de impacto a 0°C. Foi seguido como referência os requisitos técnicos básicos para a qualificação de um procedimento de soldagem conforme a norma API 1104. Os resultados mostraram que, segundo os critérios da norma API 1104, apenas uma das combinações de processos foi aprovada, sendo a outra reprovada no ensaio nick-break devido à ocorrência de falta de fusão na raiz de um dos quadrantes. O processo MAG-TC na raiz exige uma habilidade específica do soldador. / API 5L X80 pipes, built with high strength - low alloy steel, are specified for the construction of pipelines to transport oil and oil products under high pressure, with consequent reduction in weight of the tubes. The most often pipeline construction used for welding circumferential pipe field in Brazil is the SMAW process, for root and filling passes. An alternative welding process to the root pass is the GMAW-STT® process, while the filling passes can be welded with FCAW-G (Flux Cored Arc Welding with Gas shielding) and FCAWS (Flux Cored Arc Welding with Self shielding). This combination of processes (GMAW-STT® + FCAW) is presented as a promising substitute for the SMAW process, bringing high-quality weld metal deposited and high productivity. The objective of this work is to study the weldability of the Brazilian API 5L X80 pipe, with 508 mm (20 inches) in diameter and 19 mm (3 / 4 inch) thick, comparing the two combinations of circumferential welding processes: GMAWSTT ® + FCAW-G and GMAW-STT® + FCAW-S. The welding was done with the ER80S-G wire in the root pass and process GMAW-STT® using pure CO2 as shielding gas. The filling passes were made with the wires E101T1-GM-H8 for FCAW-G and E91T8-G for FCAW-S. Preheat and interpass temperatures were kept constant, respectively 150 °C and 250 °C for both welding processes combinations. The joints were characterized using: chemical analysis, magnetic saturation, optical metallography and scanning electron microscopy and mechanical tests such as: Vickers hardness, tensile, bending, nick-break and Charpy V test at 0°C. It was followed API 1104 standard as reference to the basic technical requirements for the qualification of a welding procedures. The results showed that, according to the criteria of the API 1104 standard, only one combination of the two processes was approved. The other combination was reproved in the nick-break test due to lack of fusion occurred in one of the quadrants in the root pass. The GMAW-STT® process at the root pass requires a specific skill of the welder.