Thesis (Ph. D.)--Lehigh University, 2000. / Includes bibliographical references and vita.

Climate change during the last 2.5 million years is characterised by glacial-interglacial cycles of fluctuating sea level and temperature increasing in magnitude and duration towards the present day. The central North Sea preserves these glacial-interglacial cycles in an expanded sedimentary sequence creating a high resolution palaeo-climatic record. Basin-wide, low-resolution 3D seismic data, covering more than 80,000 km2 of the central North Sea, is combined with high-resolution, broadband 3D seismic, regional 2D seismic and local ultra-high resolution seismic from the Dogger Bank windfarm development zone in order to investigate in full the sedimentary sequence. The evolution of the basin is analysed along with the preserved geomorphological landforms in order to build a framework for the development of the North Sea and its changing palaeo-environments from the inception of the Quaternary (2.58 Ma) until the extensive glacial unconformity formed during the Elsterian (0.48 Ma).At the onset of the Quaternary the structure of the North Sea was that of an elongate marine basin, rapidly infilled from the south by continued progradation of the large clinoformal deposits of the southern North Sea deltaic system. The basin rapidly decreased in extent and depth however it was not until around 1.1 Ma that the broad, shallow shelf of the present day was fully established. A revision of the current seismic stratigraphy is proposed, identifying four new Members within the Aberdeen Ground Formation taking into account the development of the basin through time. Powerful downslope gravity currents dominated the basin during much of the early Quaternary, although a well-established, anti-clockwise tidal gyre acted to gently modify the gravity currents. Iceberg scouring was nearly continual from the onset of the Quaternary until grounded ice sheets began to penetrate into the basin from 1.7 Ma, more than half a million years before any previous estimates. Effects of confluence of the British and Fennoscandian ice sheets are observed from 1.3 Ma. The tunnel valleys of the Dogger Bank represent a continuation of the North Sea tunnel valley network, interacting with both older glaciotectonic thrusting and younger glaciotectonic folded deformation.

Doctor of Philosophy / Department of Civil Engineering / Hayder A. Rasheed / The use of carbon fiber reinforced polymer (CFRP) anchors can improve the performance of reinforced concrete (RC) beams strengthened in flexure with CFRP sheets. This improvement results from delaying or controlling the debonding of FRP sheets at failure. In this research, six full-scale T beams and six full-scale rectangular beams are prepared and tested as two separate series. All the specimens are strengthened identically using three layers of unidirectional CFRP sheets and one layer of bidirectional CFRP sheet. The first strengthened beam in each series is anchored with side GFRP bars inserted longitudinally to both sides of the beam. The second strengthened beam in each series is anchored with GFRP patches applied to both sides of the beam. CFRP spike anchors are utilized for the other beams in the two series. The third beam in each series is secured with CFRP spike anchors of 16 mm diameter at 140 mm spacing along the shear span. The fourth strengthened beam in each series is anchored with CFRP spike anchors of 19 mm diameter at 203 mm spacing along the shear span. Four CFRP anchors are applied to each shear span of the fifth beam in each series with 16 mm- diameter (spaced at 406 mm) to secure the flexural CFRP sheets. An end CFRP anchorage technique is considered for the last beam in each series, which includes installing one CFRP spike anchor placed at 76 mm from the free edge of CFRP sheets. The beams were tested under four-point bending until failure and the results for each series are evaluated. In addition, the outcome is compared with other anchorage techniques that have been examined by some researchers utilizing the same beam geometry and properties. The experimental testing and nonlinear analysis showed improvement in the flexural performance of anchored beams compared with those strengthened beams without anchorage. By attaining debonding or rupture failure modes for the T beams and concrete crushing failure mode for the rectangular specimens, the ultimate sectional force capacity is achieved. Accordingly, the results prove that the anchors offer an effective solution against premature debonding failure.

This thesis offers four scientific outings to the neighbourhood of Borovany. Task of these outings is to check and improve pupils knowledge. They are proposed for pupils of 3rd, 4th and 5th class of elementary school and to each of them are created working sheets.

This thesis deals mainly with introduction to iterations and with implementation possibilities to high-school education. Extends the overview of elementary functions and depth of understanding by students. There are prepared working sheets and propositions of motivation to ease making sense of this area of mathematics.

The goal of this thesis is to improve our understanding of the Greenland ice sheet (GrIS) and how it responds to climate change. This was achieved using ice core records to infer elevation changes of the GrIS during the Holocene (11.7 ka BP to Present). The inferred elevation changes show the response of the ice sheet interior to the Holocene Thermal Maximum (HTM; 9-5 ka BP) when temperatures across Greenland were warmer than present. These ice-core derived thinning curves act as a new set of key constraints on the deglacial history of the GrIS. Furthermore, a calibration was conducted on a three-dimensional thermomechanical ice sheet, glacial isostatic adjustment, and relative sea-level model of GrIS evolution during the most recent deglaciation (21 ka BP to present). The model was data-constrained to a variety of proxy records from paleoclimate archives and present-day observations of ice thickness and extent.

Environmental change in the Arctic proceeds at an unprecedented rate. The Pliocene epoch (5-2.65 million years ago) represents an analog for future climate conditions, with pCO2 and continental configurations similar to present. Yet conditions in the Pliocene Arctic are poorly characterized because of sparse sampling. The records that do exist indicate periods of extreme warmth, as well as the first expansion of large ice-sheets in the Northern Hemisphere, took place from the end of the Pliocene into the early Pleistocene. Understanding these deposits and their implications for our future requires developing a sense of climatic evolution across the Plio-Pleistocene transition and especially during the intensification of Northern Hemisphere Glaciation (iNHG) ~2.7 million years ago. Here we reconstruct environmental change in the Arctic using a suite of organic geochemical proxies in a sedimentary archive recovered from Lake El'gygytgyn, Arctic Northeast Russia. We use the distribution of branched glycerol dialkyl glycerol tetraethers (brGDGTs) and the hydrogen isotopic composition (δD) of plant leaf-waxes (n-alkanes) to reconstruct relative temperature change across the interval spanning 2.8 to 2.4 million years ago. Our work demonstrates that, following the first major glaciation of the Northern Hemisphere, it took multiple glacial cycles for the Arctic to become synchronized with the climatic changes recorded in the deep ocean. This work has implications for understanding the role of sea-level, sea-ice, vegetation and carbon-cycle feedbacks in a changing Arctic.

Magister Commercii - MCom / This research project focuses on the application of process improvement techniques in a clothing manufacturer to address delay problems in workflow in the factory. The objective of the research is threefold; investigate delays at the beginning of production and make suggestions, show the usefulness of continuous improvement techniques in improving activities in a clothing manufacturer and demonstrate how action research can be used in doing research in production and operation management. Using tools such as flow charts, check sheets, pareto analysis, fishbone diagrams, interviews and the "ask why five times" tool, an investigation into delays led to a second investigation into sewing defects. This established that these sewing defects are caused mainly by time constraints, the malfunctioning of machines, the wrong handling of garments, and previous operations. After an investigation using the above tools it was established that these defects could be addressed by setting realistic targets, doing regular maintenance on machines, cautioning operators to be more careful during their operations, and encouraging regular checks on garments before the next operation. The action learning methodology led to the following lessons; selecting a correct measuring tool is important, that not all tools need to be used, and that it takes time to do a research project using this method.

The Greenland and Antarctic ice sheets are losing mass and contributing to global sea-level rise. Ice shelves, floating ice attached to the margins of the ice sheets, modulate sea-level rise by restraining ice-sheet flow out towards the oceans, but are sensitive to surface melting. The formation of surface meltwater lakes on ice shelves can trigger rapid ice-shelf collapse. However, surface meltwater also flows atop ice shelves through rivers. The impact of rivers on ice-shelf stability is unknown. Previous studies of ice-shelf hydrology hypothesize that rivers mitigate the damage-potential of lakes by removing surface water off of the ice shelf, but also suggest that rivers enhance ice-shelf fracturing by incising into areas of already thin ice. This dissertation is focused on exploring the role of rivers on ice-shelf stability using remote sensing datasets, conceptual models, and Augmented Reality (AR). Focusing on ice shelves in Greenland, I present the discovery of a new ice-shelf surface hydrology feature, an ice-shelf estuary, and demonstrate its potential to weaken ice shelves. I fully document this new process on the Petermann Ice Shelf, where flow reverses at the mouth of the Petermann Estuary. This study marks the first observation of ocean water atop an ice shelf. I also document the initiation and growth of fracturing along the estuary channel, and a history of rectilinear calving events, where icebergs calve along longitudinal rivers. Based on this analysis of the Petermann Estuary, I propose a new mechanism for damaging ice shelves: estuarine weakening. I present evidence that this process also occurs on the Ryder Ice Shelf in northwest Greenland. My analysis demonstrates that the role of rivers on ice-shelf stability depends on how the river mouth evolves. If ice-shelf waterfalls at the river mouth incise to sea level and form estuaries, flow reversal will modulate water export off the shelf and maintain the damage-potential of lakes, and estuarine weakening may lead to a new mode of ice-shelf calving. By analyzing the three-dimensional (3D) structure of the Petermann and Ryder Ice Shelves and Estuaries with remote sensing and radar data, I find that basal channels are an important driver of estuary development as they dictate the linearity of surface rivers. Determining the role that basal channels play in estuary formation requires accurate and appropriate data visualization tools. I develop AR applications to visualize radar data on ice shelves, towards enabling more intuitive and sophisticated interpretation of the ice-shelf structure in 3D. Through simple conceptual modeling, I suggest that although basal channels precondition ice-shelf estuary formation, estuary formation is strongly controlled by river incision. Finally, I present a model of ice-shelf estuary formation as a function of surface and basal melting. Using this conceptual model, I predict that ice-shelf estuaries could form in Antarctica in the near future. Surface melting in Antarctica is predicted to increase in under half a century. Estuary formation in Antarctica will be accelerated by lengthening of the melt season, and estuaries may form far from the calving front if rivers intersect upstream rifts. I show that ice-shelf estuaries could evolve from ice-shelf rivers in a warming Antarctica, introducing new ice-shelf weakening mechanisms. This increases the urgency to understand and include ice-shelf estuarine processes in ice-sheet models.

Tissue-pappersmarknaden växer fort och är konkurrenskraftig, det finns i dagsläget intresse att producera ett papper med hög mjukhet till ett lägre pris. Vid tissue-papper produktionen står fibrerna för en stor andel av den totala kostnaden, därför finns det en efterfrågan att kunna minska materialkostnaderna. Barrveden ger främst styrka till tissue-pappret och lövveden bidrar med mjukhet till pappret. Tissue-papper tillverkas vid låga ytvikter, därför fokuserade studien på de mekaniska egenskaperna vid lägre ytvikter. Tidigare forskning har påvisat att mekaniska egenskaperna minskar kraftig vid lägre ytvikter [5]. Att jämföra löv-och barrvedsmassor för att erhålla information om fiberegenskaper och mekaniska egenskaper är därför intressant, speciellt vid lägre ytvikter. I denna studie har de mekaniska egenskaperna testats på ark som tillverkats i Innventias massaprovningslabb, för att se hur egenskaperna ändras med ändrad ytvikt och hur olika massatyper skiljer sig. Relationer mellan barr-och lövvedsmassorna kommer uppmärksammas och trender åskådliggöras. Studien delades upp i tre tester. Första testet var utvärdering av finmaterialretentionen med slutet bakvatten vid arkning, vilket utfördes för att veta när finmaterialhalten i bakvattnet nått jämvikt. Andra testet var utvärdering av massor och mekaniska egenskaper. Ark tillverkades av 3 barrvedsmassor och 3 lövvedsmassor med olika ursprung och fiberegenskaper. De mekaniska egenskaperna testades i dragprovare, Ball Burst Strength och fibrerna karaktäriserades i fibertester. Tester för att erhålla avvattningsegenskaper och fibersvällningsgrad utfördes även i massaprovningslabbet. Det tredje testet var utvärdering av björkmassa vid olika malningsnivåer. Testet utfördes på en björkmassa som malts vid 3 olika malningsnivåer (50, 100, 150 kWh/ton), för att undersöka malningens inverkan och om malningen kunde optimeras. Testerna på massorna var precis som i det andra testet. Finmaterialretentionen i första testet nådde en jämvikt vid ungefär 4 – 6 tillverkade ark och då visade de mekaniska egenskaperna stabila värden. Finmaterialuppbyggnaden fortsattes därför med 10 labark i resterande försök för att säkerställa att finmaterialjämvikt nås. De mekaniska egenskaperna i test 2 var högst för barrvedsarken och de relativa skillnaderna mellan olika råvaror var tydliga för barrvedsarken, även vid lägre ytvikter. Lövvedarkens relativa skillnader var svåra att tyda vid lägre ytvikter, över 30 g/m2 kunde skillnader ses. Lövvedarkens mekaniska egenskaper nådde ett maximum vid 30 g/m2 därefter nådde alla mekaniska egenskaper en platå, medan ingen platå kunde identifieras hos barrveden. Barrvedsarken når förmodligen ett maximum efter 60 g/m2. De massor som erhöll högst mekaniska egenskaper var de med långa och flexibla fibrer, medan de med korta och styva fibrer fick lägre mekaniska egenskaper. Ball Burst-styrkorna var generellt sett högre hos barrvedsarken, vilket berodde på barrvedens längre fibrer. De malda björkmassorna erhöll högre mekaniska egenskaper än både barr-och lövvedsarken, vilket berodde på den ökade bindningsgraden som uppstått. Malda massornas egenskaper ökade kraftigt vid den första malningsgraden (50 kWh/ton) för att sedan avta. Ju längre malningen fortgår desto sämre blir bulken och mjukheten hos pappret [1]. En högre malning än 100 kWh/ton ansågs därför onödig eftersom avvattningsegenskaperna försämrades och ingen markant skillnad i mekaniska egenskaper erhölls. Ett optimum för malningen verkade finnas mellan 0 – 100 kWh/ton. / The tissue paper market is growing fast and is very competitive. The interest right now is to produce a paper with high softness at a lower cost. During the production of tissue paper the fibers stands for a large portion of the total cost, therefore there is a demand to reduce the material costs. Softwood mainly provides with strength to the tissue paper whilst hardwood contributes with softness to the paper. Tissue paper is manufactured at a low grammage, therefore the study is focusing on the mechanical properties at lower grammages. Previous research has shown that the mechanical properties decrease rapidly at lower basis weight. To compare hardwood and softwood pulps to obtain information on the fiber properties and mechanical properties is therefore interesting, especially at lower basis weights. In this study the mechanical properties has been tested on sheets that was manufactured at Innventias pulp testing lab, to see how the properties change with modified basis weight and when pulp types differs. Relations between hardwood and softwood pulps were recognized and trends were illustrated. The study was divided into three tests. The first test was to evaluate the fines retention in a closed white water system with recirculation, whilst making sheets. The evaluation was performed in order to know when the fines reached equilibrium in the system. The second test was the evaluation of different pulps and mechanical properties. The sheets were made with 3 softwood pulps and 3 hardwood pulps, all the pulps had different origin and fiber properties. The mechanical properties were tested in a tensile tester, Ball Burst Strength and the fiber characterization was performed in a fibertester. There were also tests to obtain the dewatering and fiber swelling properties. The third test was the evaluation of birch pulp at different refining levels. The test was conducted on a birch pulp which had 3 different refining levels (50, 100, 150 kWh/ton), to investigate the effect of the refining and if the refining process could be optimized. The paper testing and characterization was exactly as the second test. The fines retention in the first test reached equilibrium at 4 – 6 sheets and the mechanical properties showed stable values after the equilibrium was reached. The fines retention process was therefore decided to be made with 10 laboratory sheets to ensure that the fines reached equilibrium. The mechanical properties in test 2 were highest for the softwood sheets and the relative changes between various pulps were clear, even at lower basis weight. The hardwoods relative changes were hard to decipher at lower basis weights, differences could be seen at grammages higher than 30 g/m2. The hardwood sheets mechanical properties reached a maximum at 30 g/m2, followed by a plateau, whilst no plateau was identified for the softwood sheets. The softwood sheets probably reach a maximum after 60 g/m2. The pulps that obtained highest mechanical properties were those with long and flexible fibers, whilst those with shorter and stiffer fibers had lower mechanical properties. Ball Burst Strength was generally higher for the softwood sheets, due to the long fibers that the softwood had. The refined birch pulps received higher mechanical properties than the unrefined hardwood and softwood pulps, due to the increased degree of bonding that has occurred in the sheets. The refined pulps properties increased vigorously at the first refining degree (50 kWh/ton) and then decreased. The longer the refining proceeds, the worse the paper bulk and softness become [2]. A higher refining than 100 kWh/ton was considered unnecessary as the dewatering properties became worse and no significant difference was received in mechanical properties. An optimum for the refining process seemed to be in the interval 0 – 100 kWh/ton.