Дисертації з теми "Impact compaction"

Context. Cassandra is a NoSQL Database which handles large amount of data simultaneously and provides high availability for the data present. Compaction in Cassandra is a process of removing stale data and making data more available to the user. This thesis focusses on analyzing the impact of Cassandra compaction on Cassandra’s performance when running inside a Docker container. Objectives. In this thesis, we investigate the impact of Cassandra compaction on the database performance when it is used within a Docker based container platform. We further fine tune Cassandra’s compaction settings to arrive at a sub-optimal scenario which maximizes its performance while operating within a Docker. Methods. Literature review is performed to enlist different compaction related metrics and compaction related parameters which have an effect on Cassandra’s performance. Further, Experiments are conducted using different sets of mixed workload to estimate the impact of compaction over database performance when used within a Docker. Once these experiments are conducted, we modify compaction settings while operating under a write heavy workload and access database performance in each of these scenarios to identify a sub-optimal value of parameter for maximum database performance. Finally, we use these sub-optimal parameters to perform an experiment and access the database performance. Results. The Cassandra and Operating System related parameters and metrics which affect the Cassandra compaction are listed and their effect on Cassandra’s performance has been tested using some experiments. Based on these experiments, few sub-optimum values are proposed for the listed metrics. Conclusions. It can be concluded that, for better performance of Dockerized Cassandra, the proposed values for each of the parameters in the results (i.e. 5120 for Memtable_heap_size_in_mb, 24 for concurrent_compactors, 16 for compaction_throughput_mb_per_sec, 6 for Memtable_flush_writers and 0.14 for Memtable_cleaup _threshold) can be chosen separately but not the union of those proposed values (confirmed from the experiment performed). Also the metrics and parameters affecting Cassandra performance are listed in this thesis.

This dissertation focuses on developing a predictive method for determining the dynamic densification behavior of thermite powder mixtures consisting of equivolumetric mixtures of Ta + Fe₂O₃ and Ta + Bi₂O₃. Of primary importance to these highly reactive powder mixtures is the ability to characterize the stress at which full compaction occurs, the crush strength, which can significantly influence the stress required to initiate reaction during dynamic or impact loading. Examined specifically are the quasi-static and dynamic compaction responses of these mixtures. Experimentally obtained compaction responses in the quasi-static regime are analyzed using available compaction models, and an analysis technique is developed that allows for a correct measurement of the apparent yield strength of the powder mixtures. The correctly determined apparent yield strength is combined with an equation of state to yield a prediction of the shock densification response, including the dynamic crush strength of the thermite powder mixtures. The validated approach is also extended to the Al + Fe₂O₃ thermite system. It is found that accurate predictions of the crush strength can be obtained through determination of the apparent yield strength of the powder mixture when incorporated into the equation of state. It is observed that the predictive ability in the incomplete compaction region is configurationally dependent for highly heterogeneous thermite powder systems, which is in turn influenced by particle morphology and differences in intrinsic properties of constituents (density, strength, etc.).

La compaction des bétons se rencontre le plus souvent dans le cas de choc ou d'impact sur structure en béton. Sous l'effet de fortes sollicitations de compression triaxiales, le matériau béton, initialement poreux, se densifie par réduction de la porosité initiale. L'énergie dissipée au cours de cette densification est tres importante : le matériau est fortement plastifie et endommage. Au cours d'un impact, d'autres phénomènes entrent en jeu : du cisaillement provoque par la perforation du missile, et de l'écaillage provoque par réflexion des ondes de compression sur la face non-impactée en ondes de traction. Nous proposons dans la première partie de cette thèse une modélisation de ces phénomènes basée sur la mécanique des milieux poreux, la mécanique de l'endommagement et la plasticité. Le modèle phénoménologique que nous proposons est apte à représenter les divers phénomènes physiques qui interviennent au cours d'un impact. Les comportements obtenus tant en traction qu'en compaction sont comparables avec des résultats expérimentaux. De plus le modèle propose à des propriétés de régularisation intéressantes en vue de calculs numériques par éléments finis. Dans une deuxième partie, nous proposons une stratégie expérimentale en vue de caractériser la compaction de bétons et de mortiers. Ce processus expérimental s'appuie sur deux essais statiques de compaction. Le premier de ces essais est dénommé essai uniaxial confine. Le principe de cet essai est de solliciter axialement une éprouvette cylindrique ayant un diamètre de 5 cm pour une hauteur de 10 cm, et d'empêcher son gonflement radial par une cellule cylindrique métallique de forte épaisseur. Les sollicitations maximales de compression atteintes sont alors de 1275 mpa axialement sur l'éprouvette pour une contrainte radiale de 260 mpa environ. Cet essai permet de caractériser la compaction de béton sur un trajet oedometrique. Le deuxième essai est dénommé essai triaxial hydrostatique : il résulte de l'adaptation aux matériaux très poreux d'une cellule a confinement fluide mis au point pour les matériaux métalliques. Les éprouvettes testées sont alors des mortiers et des micro-bétons. La sollicitation maximale atteinte est une pression hydrostatique de 400 mpa. Cet essai permet de caractériser des mortiers sur un trajet hydrostatique.

La présente thèse se concentre tout d'abord à mettre en place des expérimentations de compaction dynamique de poudres.Un montage expérimentale est conçu, testé puis validé. Le but de ce dernier est de générer des ondes de compaction unidimensionnelles et de pouvoir observer le milieu granulaire à l'échelle des grains. Deux types de poudres sont considérés : une poudre de polypropylène et une poudre d'explosif (RDX).Pour cela, des caméras ultra-rapides (50 000 images/s) sont utilisée pour enregistrer les essais. Une technique de corrélation d'image est utilisée pour remonter aux champs de déplacement et de vitesse des grains.Un modèle de compaction multiphasique est implémenté. Les phénomènes de friction grain/paroi sont ajoutés au modèle suite aux observation expérimentale. Une partie du travail a été consacré à l'amélioration de l'équation d'état granulaire et à sa détermination expérimentale.Les résultats numériques sont en bon accord avec les expérimentations, tant que le montage expérimental ne se déforme pas sous l'effet de la pression des grains.De premières expérimentations avec les poudres d'explosifs ont été réalisées. Le montage expérimental nécessite encore certaines améliorations mais il a prouvé son utilité dans l'étude de la transition combustion-déflagration-détonation
The first part of the present PhD focuses on the conception and the validation of an experimental set up. The aim of the experiments is to generate one-dimensional compaction waves and to observe the media at the grains scale. Two type of powder are used : polypropylene powder and an explosive powder (RDX).The experimental apparatus uses ultra-fast cameras (50 000 images/s) to record the tests. Image correlation is used to compute the displacement and velocity fields.A multiphasic compaction model is then coded. Grain/wall friction is added as the experimental work underlined its importance. Additional work has been provided concerning the granular equation of state and its experimental determination.Numerical results are in good agreement with the experimenations, as long as the experimental set up is not deformed because of the grains' pressure.A few experiments have been done with explosive powders. The experimental set up still needs some improvement but it proved its usefullness for deflagration to detonation studies

Published Article
This study focuses on trials conducted on plots in the Leratong and Mpho vegetable gardens in the Eastern Free State. The aim was to investigate the possible impact of soil compaction on the growth of carrots planted on loosened (treated) and unloosened (untreated) soil. Aspects such as sprouting, vegetative length after 14 days of sprouting and diameter, as well as the length and mass of carrots after harvesting, were observed and compared between the treated and untreated carrot plots. Although there was no significant (P>0.05) difference between the two soil management practices applied in all locations, as well as the vegetative growth in the locations, a significant (P<0.05) difference between the length of carrots from the treated and the untreated plots was observed.

The beaches of Broward County, Florida are a prevalent nesting site for loggerhead (Caretta caretta) sea turtles, however extensive beach erosion is threatening critical nesting habitat. Beach renourishment, the process of transporting offshore or upland sediment onshore, is a widely used method of replenishing lost sand. However, renourishment can negatively affect sea turtle nesting habitat by increasing beach compaction; the resistance to applied pressure in pounds per square inch (psi). Increased sand compaction impedes the digging of the female which affects nesting success. The influence of beach compaction on sea turtle nesting patterns has never been previously examined over the course of a nesting season on Hillsboro and Deerfield Beach. Therefore, this study was designed to examine beach compaction data for Hillsboro, a mostly natural beach, and Deerfield, a completely renourished beach, during the 2010 nesting season and analyze the compaction data against 2010 nest and false crawl (FC, non-nesting emergence) data. Compaction readings were collected during every other week March-October using a soil compaction meter at every other street address along three beach positions, the dune base, mid-beach, and average high tide line (HTL); and at three depths, 15 cm, 30 cm, and 45 cm. Values were not statistically different throughout the season for each beach, so seasonal mean compaction values were used for each beach position and depth. Hillsboro compaction values were rarely over 500 psi (35 kg/cm2), even at 45 cm depth. Deerfield compaction values exceeded the 600 psi (42kg/cm2) measurement limit of the meter in approximately 60% of the compaction values at 30 cm or 45 cm depth. Sand compaction data was analyzed for any trends between beaches as well as within each beach. Historical data shows higher loggerhead nesting success, the number of nests/total number of crawls (including FC) x 100, on Hillsboro Beach than on Deerfield Beach. The average beach compaction values were compared to nesting success and to nest and FC density within each station area. There was a significant inverse relationship (p<0.05) between beach compaction and nesting success at each of the beach positions and depths, when both Hillsboro and Deerfield Beaches were analyzed together, except at the Mid 30 cm and Dune 45 cm depth. The strongest relationship for the combined beaches was at the HTL 15 cm depth (R2=0.3821, p<0.001). When Hillsboro was analyzed alone, beach compaction and nesting success was only significantly inversely related (R2=0.0875, p<0.02) at the HTL 15 cm depth. This demonstrates that while increased beach compaction may partially influence nesting success, there are likely other beach characteristics that contribute to nest site selection of loggerheads in Northern Broward County. The inverse relationship between Hillsboro mean beach compaction and nest density (nests per meter) was significant only at the HTL 15cm depth (p<0.002) and the inverse relationship between mean beach compaction and false crawl density (FC per meter) in Hillsboro was only significant at the Dune 15 cm (p<0.019) and the Dune 30 cm (p<0.038) depths. Although, increased beach compaction was expected to relate to higher FC density, FC density showed a significant inverse relationship to mean beach compaction at all Deerfield Beach positions and depths in and this suggests off-shore factors may be affecting nest site selection.

La compaction et l'orniérage des sols forestiers par les engins lourds constituent des enjeux très importants concernant la gestion durable des forêts. Dans cette thèse nous avons examiné l'état d'orniérage d'un massif forestier du nord de la France (forêt de Compiègne) à l'aide d'un levé LIDAR (Light Dectection And Ranging) aéroporté, puis nous avons évalué la résilience des sols après tassement à une échelle pluri-décennale. Les modèles numériques de terrain (MNT) traités par "local relief modelling" (LRM) ont été utilisés pour proposer un indicateur de la densité de l'orniérage (RD). La résilience physique et biologique des sols après le tassement a été évaluée pour deux chronoséquences (Podzol et Luvisol) établies par une approche de substitution temps / espace couvrant une période de 45 ans. Les paramètres mesurés pour étudier la résilience sont : la résistance à la pénétration, la respiration du sol, le pH, les traits hydromorphes, l'enracinement, ainsi que la diversité de microarthropodes évaluée par l'indice QBS-ar. Nous trouvons qu'à l'échelle de tout le massif, la surface impactée par les passages d'engins est en moyenne de 40% mais aussi qu'elle varie à une échelle très fine au sein des unités de gestion. L'occurrence de nombreuses espèces herbacées varie avec la densité d'orniérage. La respiration à la surface du sol et la diversité de microarthropodes sur l'horizon 0-10 cm sont restituées en moins de 10 ans. La résistance à la pénétration du sol se reconstitue progressivement depuis la surface vers la profondeur. La résilience complète sur une profondeur de 30cm est évaluée à 60 ans pour le Luvisol et 80 ans pour le Podzol
Forest soil rutting and compaction by heavy machines is one of the most important issues concerning the sustainable management of forest. In this thesis, we examined the soil rutting in a forest massif on Northern France (Compiègne forest) using airborne LIDAR (Light Detection And Ranging), then we evaluated the recovery of soil after compaction at multi-decades’ scale. The Digital Terrain Models (DTM) treated using the Local Relief Modelling tool (LRM) were used to suggest an indicator of rutting density (RD). The physical and biological recovery of soil were evaluated using two chronosequences (Podzol and Luvisol) established adopting a space for time substitution approach and covering a period of 45 years. The parameters used to examine the recovery were: the penetration resistance, the soil respiration, the pH, the hydromorphic features, the rooting, and the microarthropod diversity evaluated by the QBS-ar index. As results, the impacted surface by rutting was 40% on average, where it varies at fine scale within the forest management unit. The occurrence of many herbaceous species varies with respect to the rutting density. The surface respiration and the microarthropod diversity were recovered in 10 years on the horizon of 0-10 cm. The penetration resistance showed a progressive recovery starting from the surface to the deeper layers. The complete recovery, of the first 30 cm, was evaluated to be achieved in 60 years for the Luvisol, and in 80 years for the Podzol

Sublevel caving (SLC) is a mass mining method relying on the flowability of the blasted material. The ore is blasted in slices against caved material which is mainly waste rock. The result of the confined blast is greatly influenced by the interaction between the blasted material and the caved material. During blasting both materials change characteristics; the blasted material increases its porosity and compressibility due to breakage and swelling while the caved material is compacted and decreases in porosity and compressibility. The understanding of the mechanisms involved in this process is of significant importance. The behavior of the caved material (confining material) was studied in laboratory under dynamic loading. A new apparatus was developed to conduct impact tests to simulate blasting conditions. The tested material was a blend of crushed waste rock from drift development in the Kiirunavaara mine with maximum particle size 32 mm. The material was tested for two conditions, i.e. dry and wet (pendular state), and with different impact velocities (low (5 m/s), medium (8 m/s) and high (10-12 m/s)). During the impact tests, two types of measurements were taken; dynamic measurements based on the recordings from the installed accelerometers on the machine and static measurements pre- and post-impact. Additionally, the angle of repose, the impact duration, and the fragmentation was measured. In addition to the laboratory tests, small-scale blasting tests were carried out to investigate the burden behavior in confined conditions. The blasted specimen was a cuboid magnetic mortar block and the confining material was crushed concrete with maximum particle size 16 mm. The blocks were instrumented with custom-made incremental displacement sensor. After the analysis of the results from the above experimental work, two confined pillar tests (test #1 and test #2) were carried out at the Kiirunavaara mine. The preparation work for the pillar tests involved the development of instrumentation and installation techniques. The experimental configuration contained two blastholes and measurement holes in between the blastholes drilled from the neighboring drift. Test #1 mainly focused on the evaluation of the instrumentation and techniques while test #2 was focused on the interaction between the blasted burden and the confining material. The confining material in test #1 was a blend of ore and waste material from drift development at the Kiirunavaara mine. The characteristics of the material were unknown. Test #2 was split into two parts, the confining material in the first part was the same as in the laboratory impact tests and the second part of the pillar was confined by caved masses. The instrumentation was installed in the burden of the pillars and was equipped with accelerometers and displacement sensor. Additional instrumentation was also installed in the confining material. The burden in the small-scale blasting tests reached maximum velocity 29 m/s and maximum displacement 12.6 mm. In pillar tests, the burden movement was in the range of 0.9 to 1.1 m. In both pillar tests, burden erosion material was observed in the gap between the intact and the blasted burden. This material was finer compared to the blasted burden. The origin of this material was from the vicinity of the blastholes. The results of the laboratory tests showed that the wet material exhibited larger compaction zone than that of the dry material. The wet material showed apparent cohesion close to the impact surface of the tested material. A similar observation was made in test #2 where an agglomeration of the confining material, as a result of apparent cohesion, was observed on the surface of the blasted burden. The displacement data from the instrumentation in the burden and inside the confining material showed that the compaction zone follows an inverse exponential behavior. After the blast steeper angles of repose were measured indicating higher frictional forces between the particles. Moreover, the evidence of apparent cohesion and a larger angle of repose indicated the introduction of tensile strength in the material. The mass of the confining material was compressed elastically and plastically during the blast. After the blast, the material recovered its elastic deformation and pushed the blasted burden backward as observed in the small-scale blasting tests and the pillar tests. At this stage, the burden erosion material was compacted. Hence, there were 3 materials, i.e. burden erosion material, burden and confining material, which were compacted with different compaction rates. This condition promotes interlocking of the particles in the materials. If this behavior is correlated with a production SLC ring, then it indicates disturbances in flowability of the blasted material.

This work focuses on understanding the impact-initiated combustion of aluminum powder compacts. Aluminum is typically one of the components of intermetallic-forming structural energetic materials (SEMs), which have the desirable combination of rapid release of thermal energy and high yield strength. Aluminum powders of various sizes and different levels of mechanical pre-activation are investigated to determine their reactivity under uniaxial stress rod-on-anvil impact conditions, using a 7.62 mm gas gun. The compacts reveal light emission due to combustion upon impact at velocities greater than 170 m/s. Particle size and mechanical pre-activation influence the initiation of aluminum combustion reaction through particle-level processes such as localized friction, strain, and heating, as well as continuum-scale effects controlling the amount of energy required for compaction and deformation of the powder compact during uniaxial stress loading. Compacts composed of larger diameter aluminum particles (~70µm) are more sensitive to impact initiated combustion than those composed of smaller diameter particles. Additionally, mechanical pre-activation by high energy ball milling (HEBM) increases the propensity for reaction initiation. Direct imaging using high-speed framing and IR cameras reveals light emission and temperature rise during the compaction and deformation processes. Correlations of these images to meso-scale CTH simulations reveal that initiation of combustion reactions in aluminum powder compacts is closely tied to mesoscale processes, such as particle-particle interactions, pore collapse, and particle-level deformation. These particle level processes cannot be measured directly because traditional pressure and velocity sensors provide spatially averaged responses. In order to address this issue, quantum dots (QDs) are investigated as possible meso-scale pressure sensors for probing the shock response of heterogeneous materials directly. Impact experiments were conducted on a QD-polymer film using a laser driven flyer setup at the University of Illinois Urbana-Champaign (UIUC). Time-resolved spectroscopy was used to monitor the energy shift and intensity loss as a function of pressure over nanosecond time scales. Shock compression of a QD-PVA film results in an upward shift in energy (or a blueshift in the emission spectra) and a decrease in emission intensity. The magnitude of the shift in energy and the drop in intensity are a function of the shock pressure and can be used to track the particle scale differences in the shock pressure. The encouraging results illustrate the possible use of quantum dots as mesoscale diagnostics to probe the mechanisms involved in the impact initiation of combustion or intermetallic reactions.

Thesis (PhD (Conservation Ecology and Entomology))--University of Stellenbosch, 2010.
ENGLISH ABSTRACT: Invasive alien trees (IATs) and agriculture are rapidly altering the capacity of ecosystems to provide a variety of essential services, with decreasing habitat quality having an adverse effect on arthropod biodiversity. Although both agricultural intensification and IATs have an impact on ecosystems, it is unclear which of these two is currently the most severe. Here I compare the influences of vineyards and IATs on arthropod diversity in the Cape Floristic Region (CFR) from two perspectives. Firstly, insect diversity from four different vegetation types (native fynbos, IATs, cleared invasive alien trees (CIATs) and vineyards), and their ecotones were assessed. Secondly, soil compaction in the different vegetation types was assessed and compared to determine how soil compaction relates to arthropod species richness and abundance. Surface-active arthropods were used for these evaluations, as they were considered to be the most abundant, yet sensitive groups for these comparative assessments. Pitfall trapping, which has been widely used for such comparative studies, was the method of choice. Additionally, as a result of incidental wildfires at some of the study sites (IATs and fynbos vegetation), it was decided opportunistically to assess recovery of arthropod diversity following the impact of fire. The results categorically indicate that IATs had by far the most significant impact, in comparison with vineyards, in reducing arthropod diversity and changing assemblage composition. Both IATs and vineyards, not surprisingly, supported lower arthropod diversity compared to fynbos, while CIATs supported arthropod species richness comparable to that of fynbos. However, different invertebrate species responded differently to IAT invasion, with some species even adapted to conditions in IAT patches. Environmental factors such as leaf litter and soil compaction were strongly correlated with arthropod species richness. However, other factors, such as soil moisture content, were not correlated with species richness, despite varying significantly between different vegetation types. IATs were found to reduce soil compaction, while vineyards increased soil compaction. The ecotone between adjacent land-use types was important for sustaining high arthropod species richness, particularly for the CIATs/fynbos ecotone, followed by the interface between CIATs/vineyard and vineyard/fynbos. Some species even preferred ecotones. Surface-active invertebrate species richness declined substantially immediately after fire in both IATs and fynbos. Nevertheless, recovery was rapid, with some species recolonizing or re-establishing within three months. Indeed, both species richness and abundance were high following fire. Fire had no significant impact on arthropod assemblage within IATs, despite having a serious impact in the fynbos where a different arthropod assemblage was observed after fire. The recovery of the historic assemblages may be dependent on both the pre-fire composition of the habitat and its adjacent vegetation. Effective co-operation among conservation biologists, farmers, and landowners to actively plan the future of CFR landscape biodiversity is required.
AFRIKAANSE OPSOMMING: Indringer uitheemse bome (IUB) en landbou bedrywighede is vinnig besig om die kapasiteit van ekosisteme vir die voorsiening van „n verskeidenheid van noodsaaklike dienste, met „n afname in habitatkwaliteit en „n nadelige uitwerking op artropood biodiversiteit, te verander. Alhoewel beide, landbou intensifikasie en IUB‟s, ‟n impak op ekosisteme uitoefen, is dit onduidelik watter van hierdie twee huidig die mees ernstige een is. In hierdie studie vergelyk ek die invloed van wingerde en IUB‟s op artropood diversiteit in die Kaapse Floristiese Streek (KFS) vanuit twee perspektiewe. Eerstens, insekdiversiteit van vier verskillende vegetasietipes (natuurlike fynbos, IUB‟s, verwyderde indringer uitheemse bome (VIUB‟s) en wingerde) en hulle ekotone is bepaal. Tweedens, is grondverdigting in en van die verskillende vegetasietipes ondersoek en vergelyk om te bepaal hoe grondverdigting verband hou met artropood spesies rykheid en volopheid. Oppervlak-aktiewe artropode is vir hierdie bepalings gebruik aangesien hulle beskou word as die mees volopste, maar ook mees sensitiewe groepe vir hierdie vergelykende bepalings. Pitvalvangste, wat alom gebruik word vir sulke vergelykende studies, was die verkose werkswyse. Bykomend, as gevolg van onbeplande veldbrande in sommige studie gebiede (IUB‟s en fynbos plantegroei), is oppertunisties van die geleentheid gebruik gemaak om die herstel van artropood diversiteit na die impak van brand te bepaal. Die resultate toon duidelik aan dat IUB‟s, in vergelyking met wingerde, by verre die mees beduidende impak gehad het deur ‟n verlaging van artropood diversiteit en veranderende groeperingssamestellings. Beide, IUB‟s en wingerde, het, nie onverwags nie, in vergelyking met fynbos, laer artropood diversiteit ondersteun, terwyl VIUB‟s artropood spesies verskeidenheid, vergelykbaar met dié van fynbos, ondersteun het. Verskillende invertebrate spesies het egter verskillend gereageer op IUB indringing, en sommige spesies het selfs by toestande in IUB kolle aangepas. Omgewingsfaktore soos blaarafval en grondverdigting was sterk gekorrelleer met artropood spesies rykheid. Ander faktore, soos grondvoginhoud, was egter nie in ooreenstemming met spesies rykheid nie, ten spyte van ‟n beduidende wisseling tussen verskillende vegetasietipes. IUB‟s het grondverdigting verminder, terwyl by wingerde grondverdigting toegeneem het. Die ekotone tussen aanliggende grondgebruike was belangrik om hoë artropood spesies rykheid, veral by die VIUB‟s/fynbos ekotoon, gevolg deur die kontaksones tussen VIUB‟s/wingerd en wingerd/fynbos, te onderhou. Sommige spesies het selfs ekotone verkies. Oppervlak-aktiewe invertebraat spesies rykheid het onmiddelik na brand in beide, IUB‟s en fynbos, wesenlik afgeneem. Tog was herstel vinnig, met sekere spesies wat binne drie maande teruggekeer of hulle hervestig het. Inderdaad was beide, spesies rykheid en volopheid, hoog na ‟n brand. Brand het geen noemenswaardige invloed op artropood groeperings binne IUB‟s gehad nie, ten spyte van ‟n ernstige impak in fynbos waar ‟n verskillende artropood groepering na ‟n brand waargeneem is. Die herstel van die historiese groeperings van beide, die voor-brand samestelling van die habitat en sy aangrensende plantegroei, mag afhanklik wees. Effektiewe en aktiewe samewerking tussen bewaringsbioloë, boere, en grondeienaars om die toekoms van KFS landskap biodiversiteit te beplan, word benodig.

Répondre aux défis du développement durable exige la prise en considération des aspects économiques, sociétaux et environnementaux des projets. Dans le domaine des terrassements, les actions portent notamment sur l'optimisation de la valorisation des matériaux extraits grâce aux techniques de traitement des sols. Le projet s'est principalement porté sur les produits de traitement dérivant de la transformation de matières premières renouvelables : solutions « enzymatiques », lignosulfonates et solutions acides. Des données factuelles concernant les effets des traitements sur les caractéristiques hydromécaniques de quatre sols (un limon, un sol argileux et deux sables) ont été acquises mettant en évidence une augmentation de l'efficacité du compactage après traitement du limon au produit enzymatique et au lignosulfonate. La recherche des mécanismes d'action s'est fondée sur une étude de la microstructure par microscopie électronique à balayage et porosimétrie au mercure complétée par l'évaluation des effets d'un ajout de produits tensioactifs sur les propriétés des sols. L'objectif de l'étude dépasse cependant l'évaluation des modalités d'action des produits et vise également à prendre en compte les préoccupations environnementales. Ainsi, une étude d'analyse du cycle de vie a été menée pour chaque application ce qui a permis d'identifier les conditions optimales pour lesquelles les traitements combinent intérêts techniques et environnementaux. Ces conditions sont réunies lors du compactage des sols secs sous réserve que l'étape de production et de transport des produits ne soit pas excessivement pénalisante comme mis en évidence lors de l'étude de sensibilité
Sustainable development principles lead earthworks companies to use all natural materials and to reduce the environmental impact of their activities. In this context, the use of industrial organic products derived from the processing of renewable matter has been proposed. In this study, three non traditional products have been selected: an enzymatic solution, a lignosulfonate and an acid solution. In a first approach, hydromechanical properties of four treated soils (a silt, a clayey soil and two sands) were investigated. The experimental results showed interesting applications for the silt when its natural water content is low. Indeed, the compaction ability of the soil was increased after enzymatic and lignosulfonate treatments. Thus, savings of water and energy could be expected during the construction stage. To gain a better understanding of the mechanisms of the treatment products, the microstructure of treated soil were investigated with scanning electron microscopy, mercury injection porosity and was completed by the study of a surfactant addition in soils. The global aim of the study was beyond the characterization of mechanical behavior of treated soils, therefore, environmental balance was also estimated for the different applications defined in accordance to the experimental results. For enzymatic and lignosulfonate treatments, a comparison of the global environmental impact was done thanks to a life cycle assessment methodology. This approach showed that technical and environmental interest are associated for the compaction of dry soils when the production and transport steps have limited environmental impact as demonstrated in the sensitivity analysis

Paleoclimatic archives, such as lake sediments, extend our understanding of terrestrial and aquatic ecosystem dynamics in relation to climate variability beyond the period covered by instrumental data. In this context, annually laminated (i.e. varved) lake sediments are particularly valuable, as they offer high temporal resolution and undisturbed sediment. However, in order to extract reliable climate information from lake sediments, a careful calibration with the processes controlling the sediment formation is essential. This thesis combines limnological and paleolimnological data from a varved, boreal lake in northern Sweden (Nylandssjön, Nordingrå) collected over different time scales. The main aim of the thesis is to gain a more refined insight into which processes are reflected in the sedimentary diatom assemblage. More specifically, sequential sediment trap records were coupled with physical, chemical and biological lake monitoring and environmental data for comparison and validation with the varved sediment record. The main result of the thesis is that timing, succession and inter-annual variability of key limnological and environmental processes (e.g. ice-cover duration, lake over-turn or catchment run-off) are of major importance for the sedimentary diatom assemblage formation. Continuous monitoring of physico-chemical parameters over three consecutive years identified varying winter air temperature as a major factor influencing in-lake processes and hence the diatom record. Timing of lake over-turn and catchment run-off seemed to be the driver for monospecific diatom blooms, which are reflected in the annual sediment signal. The integrated annual diatom signal in the sediment was dominated by spring or autumn blooms, resulting either from a Cyclotella glomerata dominated spring bloom after relatively warm winter conditions, or a Asterionella formosa dominated autumn bloom after relatively cold winter conditions. The analysis of the diatom stratigraphy in the varved sediment over several decades corroborated the importance of climatic variables (late winter air temperature and NAO), even though the variables with the most predictive power for variance in the diatom data were associated with sediment composition (C, N and sedimentation rate) and pollution (Pb and Cu). Overall, the analysis of the drivers of inter-annual and decadal diatom assemblage fluctuations emphasizes the importance of winter air temperature, indicating that weather extremes may be disproportionately represented in annual sediment records in contrast to nutrient concentrations or sedimentation rate.

Au cours de la production d'hydrocarbures, l'extraction de fluides fait décroître la pression de pore dans les réservoirs (" depletion "). Ceci induit un changement du champ de contraintes qui résulte en une augmentation des contraintes effectives appliquées sur le réservoir. Les mesures in situ montrent que les variations de contraintes peuvent être décrites par un paramètre appelé chemin de chargement (stress path), défini comme le rapport entre la variation de contrainte effective horizontale et la variation de contrainte effective verticale par rapport aux conditions initiales dans le réservoir. La compaction induite par la production d'hydrocarbures peut avoir de graves conséquences dans le cas de roches faiblement consolidées car elle induit des variations des propriétés pétrophysiques des roches in situ, notamment de la perméabilité, un des paramètres les plus importants pour estimer la performance d'un réservoir mais aussi un des plus difficiles à mesurer. Pour compliquer encore les choses, la perméabilité est souvent anisotrope dans les réservoirs avec de forts contrastes entre la perméabilité horizontale kh et la perméabilité verticale kv. L'objectif de cette étude est de comprendre l'influence des chemins de chargement sur le comportement mécanique et les évolutions couplées de perméabilité pour un sable quartzeux (Sable de la Durance, DS) et un grès faiblement consolidé (grès d'Otter Sherwood, OSS, qui constitue la roche réservoir du champ pétrolier de Wytch Farm en Angleterre). Nos résultats montrent que le grès peu consolidé présente un comportement mécanique similaire à celui de roches consolidées. Au contraire, le sable présente un comportement différent, avec une transition plus graduelle entre les régimes de déformation qui nécessite d'utiliser un critère basé sur l'évolution du rayon de courbure des courbes contraintes-déformations pour déterminer les contraintes limites : cette méthode a été validée par une étude d'analyse des émissions acoustiques pour caractériser l'endommagement. Les domaines de déformation élastique et plastique ont été bien définis et les contraintes limites ont été comparées aux prédictions du modèle Cam-Clay modifié et du modèle d'enveloppe limite normalisée. Les perméabilités horizontale et verticale ont été mesurées sous contraintes. Pour analyser l'influence des effets de bord dans les essais mécaniques, les perméabilités mesurées soit classiquement sur toute la longueur de l'échantillon, soit entre deux points intermédiaires ont été comparées. Pour l'écoulement horizontal, les facteurs géométriques et facteurs d'anisotropie ont été déterminés par des simulations numériques en éléments finis afin de pouvoir déterminer les vraies valeurs de perméabilité horizontale. L'évolution de la perméabilité suit l'évolution de la déformation des matériaux et est contrôlée aussi bien par la déformation volumique que par la déformation en cisaillement. A partir de nos mesures il est possible de séparer l'effet de la pression moyenne de l'effet de la contrainte déviatorique sur l'évolution de la perméabilité en construisant des cartes d'isoperméabilités dans l'espace des contraintes. Enfin une modélisation élasto-plastique a été réalisée pour prédire le comportement hydro-mécanique du grès faiblement consolidé. L'approche utilisée permet de prédire de manière satisfaisante l'évolution de la perméabilité avec les contraintes, à partir d'une loi exponentielle fonction de la déformation effective. Au contraire, pour le sable de la Durance le lien entre l'évolution de la perméabilité et la déformation est loin d'être évidente, notamment aux faibles contraintes où la réduction de perméabilité est très rapide. Pour mieux comprendre ces évolutions de perméabilité, une analyse de l'endommagement a été réalisée par des mesures sur échantillons et en utilisant des techniques d'imagerie à plusieurs échelles.

Au cours de la production d'hydrocarbures, l'extraction de fluides fait décroître la pression de pore dans les réservoirs (« depletion »). Ceci induit un changement du champ de contraintes qui résulte en une augmentation des contraintes effectives appliquées sur le réservoir. Les mesures in situ montrent que les variations de contraintes peuvent être décrites par un paramètre appelé chemin de chargement (stress path), défini comme le rapport entre la variation de contrainte effective horizontale et la variation de contrainte effective verticale par rapport aux conditions initiales dans le réservoir. La compaction induite par la production d'hydrocarbures peut avoir de graves conséquences dans le cas de roches faiblement consolidées car elle induit des variations des propriétés pétrophysiques des roches in situ, notamment de la perméabilité, un des paramètres les plus importants pour estimer la performance d'un réservoir mais aussi un des plus difficiles à mesurer. Pour compliquer encore les choses, la perméabilité est souvent anisotrope dans les réservoirs avec de forts contrastes entre la perméabilité horizontale kh et la perméabilité verticale kv.L'objectif de cette étude est de comprendre l'influence des chemins de chargement sur le comportement mécanique et les évolutions couplées de perméabilité pour un sable quartzeux (Sable de la Durance, DS) et un grès faiblement consolidé (grès d'Otter Sherwood, OSS, qui constitue la roche réservoir du champ pétrolier de Wytch Farm en Angleterre). Nos résultats montrent que le grès peu consolidé présente un comportement mécanique similaire à celui de roches consolidées. Au contraire, le sable présente un comportement différent, avec une transition plus graduelle entre les régimes de déformation qui nécessite d'utiliser un critère basé sur l'évolution du rayon de courbure des courbes contraintes-déformations pour déterminer les contraintes limites : cette méthode a été validée par une étude d'analyse des émissions acoustiques pour caractériser l'endommagement. Les domaines de déformation élastique et plastique ont été bien définis et les contraintes limites ont été comparées aux prédictions du modèle Cam-Clay modifié et du modèle d'enveloppe limite normalisée. Les perméabilités horizontale et verticale ont été mesurées sous contraintes. Pour analyser l'influence des effets de bord dans les essais mécaniques, les perméabilités mesurées soit classiquement sur toute la longueur de l'échantillon, soit entre deux points intermédiaires ont été comparées. Pour l'écoulement horizontal, les facteurs géométriques et facteurs d'anisotropie ont été déterminés par des simulations numériques en éléments finis afin de pouvoir déterminer les vraies valeurs de perméabilité horizontale. L'évolution de la perméabilité suit l'évolution de la déformation des matériaux et est contrôlée aussi bien par la déformation volumique que par la déformation en cisaillement. A partir de nos mesures il est possible de séparer l'effet de la pression moyenne de l'effet de la contrainte déviatorique sur l'évolution de la perméabilité en construisant des cartes d'isoperméabilités dans l'espace des contraintes. Enfin une modélisation élasto-plastique a été réalisée pour prédire le comportement hydro-mécanique du grès faiblement consolidé. L'approche utilisée permet de prédire de manière satisfaisante l'évolution de la perméabilité avec les contraintes, à partir d'une loi exponentielle fonction de la déformation effective. Au contraire, pour le sable de la Durance le lien entre l'évolution de la perméabilité et la déformation est loin d'être évidente, notamment aux faibles contraintes où la réduction de perméabilité est très rapide. Pour mieux comprendre ces évolutions de perméabilité, une analyse de l'endommagement a été réalisée par des mesures sur échantillons et en utilisant des techniques d'imagerie à plusieurs échelles
During hydrocarbon production, the extraction of fluid induces a decrease of pore pressure called depletion. This depletion causes a change in the stress field that results in an increased stress on the rock by enhancement of the effective stress in the reservoir. In situ measurements show that the stress variations can be described by the so-called stress path parameter, defined as the ratio of the change in effective horizontal stress by the change in effective overburden stress from initial reservoir conditions. This production induced compaction can have severe consequences in the case of poorly consolidated reservoirs. Compaction induces variations of petrophysical properties of in situ rocks and particularly permeability variations, one of the most important parameters controlling reservoir performance. Yet it is one of the most difficult property to measure. To complicate matters further, permeability anisotropy is often found in reservoirs. Therefore the horizontal permeability kh, may be different from the vertical permeability kv.The aim of this study is to understand the influence of stress paths on the mechanical behavior and coupled permeability evolutions of a Quartz sand (Durance Sand, DS) and a weakly consolidated sandstone (Otter Sherwood Sandtone, OSS which is the reservoir rock of the Wytch Farm oil field, UK). We found that the weakly consolidated rock presents a mechanical behavior similar to that of consolidated rocks. However, the sand shows a different behavior, with a gradual transition regime which requires the use of a curvature criterion to peak yield stresses on the stress-strain evolution plot; this criterion has been validated on the basis of Acoustic Emission analysis. The elastic and plastic deformation regimes are well identified and the determined yield stresses are fitted using the modified Cam-Clay and Elliptic Cap models for all observed onsets of plastic yielding. Both vertical and horizontal permeability have been measured during loading. To analyze the influence of end effects during loading in the triaxial cell, permeabilities measured over the mid-section and over the total core length were compared. For the horizontal flow, the geometrical and anisotropy factors were determined using Finite Element simulations in order to calculate the correct horizontal permeability. Permeability evolution follows closely the material deformation and is controlled by both volumetric and shear strains. It is possible to infer the effect of the mean pressure and/or the deviatoric stress on the permeability evolution by building isopermeability maps in the stress space. Finally, an application of elasto-plastic modeling to predict the hydromechanical behavior of the weakly consolidated rock is presented. This approach allows a satisfying prediction of the permeability evolution with stresses, using an exponential function of an effective strain. Reversely for DS, the link between strain and permeability is not obvious as permeability reduction is pronounced at early stage of loading. To understand these permeability evolutions, a damage analysis has been performed using core analysis measurements and multi-scale imaging

Compact cities, as opposed to the urban sprawl, are being advocated in many countries and regions. As a sustainable urban form, these have significant implications on the pursuit of economic, social, and environmental sustainability. However, despite their advantages, compact cities have negative impacts on urban development. Both positive and negative impacts are derived from developed countries. However, whether these impacts are applicable to developing countries remains uncertain. This research aims to examine the development and impacts of urban compaction in China. Guided by land use policies, compact development in Beijing is currently being promoted through the intensification of existing construction areas rather than the development of new large-scale areas. This research aims to explore the development of urban compactness from the perspective of time and spatial dimensions and examine the impact of compact development. To carry out this research, this thesis reviews the relevant theories on compact cities characterized as high-density developments and mixed-use developments of construction areas that have a well developed public transport system. These compact cities can be achieved through urban intensification. In this work, an indicator system for measuring urban compactness based on the features of compact cities (e.g., high-density development, mixed-use development, and public transport system) is proposed. The development of the urban compactness of an entire city during the period of 1992-2007 is also calculated according to the indicator system. In addition, the development of urban compactness in the different regions of inner city districts, outer city districts, and new towns in 1996, 2001, and 2006 are also studied. Given that compact cities have a significant impact on urban development, some indicators that reveal economic, social, and environmental development are utilized to test the impact of compact cities in Beijing through statistical studies and semi-structured interviews. The results of evaluating the urban compactness development from the entire city perspective indicate rapid population growth and urbanization, along with the rapid increase of urban density in Beijing. Compared with high-density development, mixed use development has not been as rapid. With the mass construction of the subways and the increase in the provision of public buses, the development of public transport has also improved significantly. Following these results, the impact of urban compaction is analyzed, and compact development appeared to be beneficial to economic, social and environmental development, although some of its benefits have not been embodied fully. This research further examines the spatial development of urban compactness. The findings reveal that land use in the central city has become increasingly compact and that the potential for urban compactness could be further enhanced in the outer city districts. In new towns where the urban sprawl is quite severe, high-density development and mixed-use development should be promoted. To increase accessibility, the public transport system should be further improved. By analyzing the development of urban compactness, this study suggests that the support facilities and services in Beijing are insufficient compared with population growth and urbanization occurring in the city; this inadequacy leads to the backward progress of mixed-use development. As a large city, the different regions in Beijing stand in different positions that require varied development strategies to achieve urban compaction. The study fills a gap in the literature on compact development in China and population growth as well as theoretically and empirically enriches the impact of urban compaction in the context of rapid urbanization and population growth.
published_or_final_version
Urban Planning and Design
Doctoral
Doctor of Philosophy

La solution la plus favorable cliniquement au remplacement des dents absentes est aujourd'hui la mise en place d'implants dentaires. Cette technique nécessite la maîtrise de plusieurs problématiques qui s'articulent autour des interfaces du système. Celles-ci sont au nombre de trois soit : l'interface os-implant, l'interface implant-pilier prothétique et l'interface pilier prothétique-prothèse. Dans cette étude, nous analysons les matériaux mis en présence au sein des interfaces et ce, par le biais de l'analyse mécanique afin d'apporter une contribution objective au choix clinique des matériaux par les praticiens. Les substituts osseux sont ainsi étudiés sous le prisme de leur stabilité mécanique, servant de trame à la reconstruction osseuse au contact de l'implant. Plusieurs systèmes implantaires (ensemble implant-pilier prothétique) sont ensuite étudiés pour en évaluer également la stabilité, gage de solidité du système et d'absence de dévissage. Enfin, plusieurs polymères dentaires sont évalués et comparés afin d'établir leur apport dans la solidité du complexe implanto-prothétique.

Segundo estudo de 2015 da FAO, 33% da área agricultável mundial estão degradados. Um dos principais problemas é a compactação do solo, causada pelo tráfego de máquinas ou animais em solo acima da capacidade de suporte de carga ou fora da condição de trafegabilidade. A compactação do solo desencadeia problemas ambientais e agronômicos como erosão, lixiviação e baixa produtividade. Sua reversão é um processo lento, caro, violento e ineficiente, por isso a melhor saída é previni-la. Para tanto, uma recomendação é mapeá-la regularmente. Um indicador indireto da compactação é a resistência (ou impedância) mecânica do solo à penenetração. O penetrômetro é o instrumento que mede a resistência da introdução de uma haste de ponta cônica no solo; teoricamente, solos mais compactados oferecem maior resistência. Há uma variedade de modelos de penetrômetro no mercado e literatura: bancada ou campo, manual ou automático, estático (penetrógrafo) ou dinâmico (de impacto), com ou sem registro eletrônico de dados etc. Naturalmente, surge a dúvida se é possível comparar dados de penetrômetros diferentes. Alguns trabalhos debruçaram-se sobre essa hipótese, mas a literatura ainda é escassa. Nos poucos artigos publicados, não hão há consenso a respeito da comparabilidade entre penetrômetros diferentes, que ora concordam, ora divergem. No presente trabalho, compararam-se os penetrômetros de campo Sondaterra PI-60 (impacto), Falker PLG1020 (manual) e Falker Solotrack (automático). O experimento observacional foi realizado em um latossolo vermelho eutroférrico de texturas argilosa, argiloarenosa e franco-argiloarenosa em Pirassununga-SP. A resistência mecânica foi avaliada simultaneamente pelos três penetrômetros em oito camadas entre 0,00-0,40 m, abaixo, dentro e acima do intervalo friável do local (10,2-35,1%(v/v)). Sob a mesma condição de umidade do solo, os três penetrômetros concordaram (não houve diferença estatística a 5%) em 58% das observações. Acordaram mais entre si os penetrômetros manual-automático (76%) e impacto-automático (70% das observações). Mesmo onde divergiram, as diferenças mínima, média e máxima de resistência foram respectivamente de 0,61; 0,91 e 1,23 MPa (excluindo-se a camada superficial 0,00-0,05 m), não interferindo no diagnóstico prático da compactação do solo. Em geral, PI-60 > Soltorack > PLG1020 (2,31; 2,14 e 1,91 MPa respectivamente). A compatibilidade entre penetrômetros abaixo, dentro e acima do intervalo friável foi a mesma: 31%, 36% e 33% das observações na mesma ordem. Não houve convergência em apenas três observações (de 120), todas na camada superficial. A resistência variou inversamente com a umidade do solo nos três penetrômetros, concordando com resultados semelhantes na literatura. Em média, a resistência diminuiu de 0,0596 MPa a cada acréscimo de 1% na umidade volumétrica (R2 = 0,44). Concluiu-se que é seguro comparar valores de resistência de penetrômetros diferentes desde que tenham sido coletados sob a mesma condição de umidade do solo.
According to a 2015 FAO study, 33% of the world\'s arable land is degraded. One of the main problems is soil compaction, caused by the traffic of machines or animals on soil over the load bearing capacity or outside of the trafficable condition. Soil compaction triggers environmental and agronomic problems such as erosion, leaching and low productivity. Its reversal is a slow, expensive, violent and inefficient process, so the best way out is to prevent it. To do so, a recommendation is to map it regularly. An indirect indicator of compaction is the mechanical resistance (or impedance) of the soil to penetration. The penetrometer is the instrument that measures the resistance of the introduction of a conical tipped rod into the ground; theoretically, more compacted soils offer greater resistance. There are a variety of penetrometer models in the market and literature: bench or field, manual or automatic, static (penetrograph) or dynamic (impact), with or without electronic data record etc. Of course, the question arises whether it is possible to compare data from different penetrometers. Some papers have dealt with this hypothesis, but the literature is still scarce. In the few articles published, there is no consensus about the comparability between different penetrometers, which now agree, or differ. In the present work, we compared the field sensors Sondaterra PI-60 (manual dynamic), Falker PLG1020 (manual static) and Falker Solotrack (automatic static). The observational experiment was carried out in a red eutroferric latosol (USDA oxisol) of clay, sandy clay and sandy clay loam textures in Pirassununga-SP, Brazil. The mechanical strength was evaluated simultaneously by the three penetrometers in eight layers between 0,00-0,40 m, below, within and above the friable interval of the site (10.2-35.1%(v/v)). Under the same soil moisture condition, the three penetrometers agreed (there was no statistical difference at 5%) in 58% of the observations. Best agreed among themselves the automatic-manual static (76%) and automatic-dynamic (70% of observations) penetrometers. Even where they diverged, the minimum, mean and maximum resistance differences were respectively 0.61; 0.91 and 1.23 MPa (excluding the superficial layer 0.00-0.05 m), values that do not interfere with the practical diagnosis of soil compaction. In general, PI-60 > Solotrack > PLG1020 (2.31, 2.14 and 1.91 MPa respectively). The compatibility between penetrometers below, within and above the friable interval was the same: 31%, 36% and 33% of observations in the same order. There was no convergence in only three observations (of 120), all in the superficial layer. The resistance varied inversely with soil moisture in the three penetrometers, agreeing with similar results in the literature. On average, the resistance decreased by 0.0596 MPa for each increment of 1% in the volumetric humidity (R2 = 0.44). It was concluded that it is safe to compare resistance values from different penetrometers provided they have been collected under the same soil moisture condition.

Le maintien ou l'amélioration de la biodiversité est un des objectifs importants de la gestion forestière durable. La flore du sous-bois, qui représente la partie la plus diversifiée de la flore dans les forêts tempérées, joue des rôles écologiques importants. Pourtant, elle pourrait être impactée par l'augmentation de la mécanisation de la gestion forestière. A l'échelle de la parcelle, nous avons étudié en forêt de Montargis les effets simples et combinés de caractéristiques du peuplement et de la surface en cloisonnement sur la diversité floristique du sous-bois (richesse et abondance). Les caractéristiques du peuplement (type de peuplement ou surface terrière des essences à étaient les meilleurs indicateurs de la diversité du sous-bois. La surface des cloisonnements avait un effet négligeable. A plus petite échelle – à l’intérieur du cloisonnement – nous avons étudié la réponse statistique de la diversité du sous-bois à la position dans ou hors du cloisonnement, à des facteurs micro-environnementaux (humidité du sol, compaction du sol, lumière) et aux caractéristiques du peuplement. A cette échelle, les meilleurs modèles incluaient pour les groupes écologiques la position par rapport au cloisonnement, l’humidité du sol et/ou la compaction du sol, selon le groupe écologique considéré. Au niveau espèce, la position par rapport au cloisonnement était le facteur dominant. Globalement, les cloisonnements avaient soit pas d’effet soit un impact positif sur la diversité floristique de sous-bois. Ces résultats ont dépendants du contexte écologique et historique de la forêt de Montargis. L’utilisation d’engins plus lourds ou des passages répétés sur une plus longue période pourraient changer ces conclusions
Maintaining or improving biodiversity is an important goal of sustainable forest management.Ground flora, which is responsible for most floristic diversity in temperate forests, plays multiple important roles in biodiversity but may be impacted by the increasing mechanisation of forest practices. At stand scale, we investigated in Montargis forest the individual and combined effects of tree stand attributes and skid trail area on ground flora diversity. Tree stand attributes (stand type or basal area) were the best indicators of ground flora diversity, depending on the successional traits or light preference of the species group. The effects of skid trail area were negligible. At finer scale, we studied plant response to skid trail disturbance (represented by subplot on and off skid trails), micro-environmental factors (soil moisture, soil compaction, light) and stand attribute (stand type, basal area). The best models for ecological groups included subplot location, soil moisture or soil compaction, depending on which ecological groups (classified by life form, seed bank persistence, light and moisture requirements) the species belonged to. Stand type as a covariate played a significantly important role in fine-scale diversity pattern. Subplot location was the dominant factor at species level. In conclusion, skid trails had either no impact or a positive impact on ground flora diversity. These results are dependent on the context of Montargis forest (ecological and historical), especially that mechanized harvesting is relatively recent. The employment of heavier machines and increased number of passages is likely to happen. This might induce greater soil compaction and negative effects on plant

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This paper presents an analysis of the development of self-compacting concrete with low consumption of Portland cement, and evaluates some of its properties in fresh and hardened state ( mechanical properties ). The production of concrete with low consumption of Portland cement of the concept of providing more sustainable construction based on the concrete industry, as increased longevity of raw materials deposits, reducing CO2 emissions and energy consumption and lower cost transport. It provides various technical improvements such as lower heat of hydration, shrinkage and cracking. Based on packaging concepts and particle dispersion suitable choice of materials and the use of mineral fílers and admixtures, there was obtained concrete with low consumption of cement and high strength, with a relative consumption of binder materials less than 5 kg / m³ to produce 1 MPa compressive strength. This research is characterized as a theoretical-experimental model, which were researched packaging methods of aggregates and mineral additions, studied the interaction between superplasticizer and cementitious materials, seeking a considerable reduction in cement content in mixtures of self-compacting concrete. Therefore, we used the dosage methodology presented by Gomes (2002) and also have certain mechanical properties of concrete and it is concluded by the results, the use of a structural concrete self-compacting with Portland cement consumption can reduced.
Este trabalho apresenta uma análise sobre a elaboração de concretos autoadensáveis com baixo consumo de cimento Portland, e avalia algumas das suas propriedades no estado fresco e endurecido (propriedades mecânicas). A confecção de concretos com baixo consumo de cimento Portland parte do conceito de possibilitar maior sustentabilidade da indústria da construção civil baseada no concreto, como maior longevidade das jazidas de matérias-primas, redução da emissão de CO2 e no consumo de energia e menores custos de transportes. Proporciona diversas melhorias técnicas, como menor calor de hidratação, retração e fissuração. Fundamentado em conceitos de empacotamento e dispersão de partículas, escolha adequada dos materiais e uso de adições minerais e fíleres, obtiveram-se concretos com baixo consumo de cimento e alta resistência, com consumo relativo de materiais aglomerantes inferior a 5 kg/m³ para produzir 1 MPa de resistência à compressão. Esta pesquisa caracteriza-se como um modelo teórico-experimental, onde foram pesquisados métodos de empacotamento dos agregados e adições minerais, estudada a interação entre o aditivo superplastificante e os materiais cimentícios, buscando uma redução considerável do teor de cimento nas misturas de concretos autoadensáveis. Diante disso, utilizou-se a metodologia de dosagem apresentada por Gomes (2002) e também foram determinadas as propriedades mecânicas dos concretos e conclui-se, mediante aos resultados obtidos, que é possível o emprego de um concreto estrutural autoadensável com consumo de cimento Portland reduzido.

Several decades of intensive dryland-farming in the Gadarif Region, located in the Eastern part of Sudan, has led to rapid landuse/landcover (LULC) changes mainly due to agricultural expansion, government policies and environmental calamities such as drought. The study area represents part of the African Sahel. The fundamental goal of the thesis was to assess land degradation and the impact of agriculture expansion on land cover, soil and crops production. To analyse and to monitor the LULC changes, multi-temporal Landsat data of the years 1979, 1989 and 1999 and ASTER data of the year 2009 covering an area of approximately 1200 km² were used. For this a post-classification comparison technique was applied to detect LULC changes from satellite images. Six LULC classes were identified during the classification scheme, namely cultivated land, fallow land, woodland, bare land, settlement and water. For the four dates of satellite images the overall classification accuracy ranged from 86 % to 92 %. During the three decades of the study period an extensive change of LULC patterns occurred. The cultivated areas increased significantly, covering 81 % of the previous woodland in the period 1979 – 2009. Fallow land only increased during the period 1989 – 1999. Over the three decades, urban expansion continuously increased covering an area of 23, 21 and 27 km² for the periods 1979 – 1989, 1989 – 1999 and 1999 – 2009 respectively. The detailed LULC map of the study area was obtained by using a dual polarisation (HH and HV) TerraSAR-X data of the year 2009. The different LULCs of the study area were analysed by employing an object-oriented classification approach. For that purpose, multi-resolution segmentation of the Definiens Software was used for creating the image objects. Using the feature-space optimisation tool the attributes of the TerraSAR-X images were optimised in order to obtain the best separability among classes for the LULC mapping. In addition to the classes that have been obtained by the optical data, the following LULCs resulted from SAR data: harvested land, rock, settlement 1 (local-roof buildings) and settlement 2 (concrete roof buildings). The backscattering coefficients for some classes were different along HH and HV polarisation. The best separation distance of the tested spectral, shape and textural features showed different variations among the discriminated LULC classes. An overall accuracy of 84 % with a kappa value of 0.82 was resulted from the classification scheme. Accuracy differences among the classes were kept minimal. For more than six decades in the Gadarif Region mechanised dryland farming is practised. As a result, due to continuous conventional tillage, extensive woodcutting and over-grazing, serious soil degradation occurred. To discuss the impact of LULC changes on the selected soil properties, three main LULC types were chosen to be investigated, namely: cultivated land, fallow land and woodland. In addition to the reference soil profiles, soil samples were also collected at two depths from ten sample plots for each of the LULC type. For these soil samples, various soil properties such as texture, bulk density (BD), organic matter (OM), soil pH, electrical conductivity (EC), sodium adsorption ratio (SoAR), phosphorous (P) and potassium (K) were analysed. Laboratory tests proved that soil properties were significantly affected by LULC changes. Within the different LULC types, clay content in the surface layers (0 – 5 and 5 – 15 cm) varied from 59 % to 65 %, whereas silt fractions ranged from 27 % to 37 %. Soil BD, OM and P were significantly different (p < 0·05) across the three LULC types. Soil pH was significantly different between cultivated land and woodland on one side and between fallow land and woodland on the other side. EC and SoAR values of fallow land were found to be significantly different (p < 0·05) from woodland. The dryland vertisol of the Gadarif Region in Sudan produced more than one-third of the national production of sorghum – the main food stuff in the country. Soil compaction has been recognised as one of the major problems in crop production worldwide. Soil strength and infiltration rate are important variables for understanding and predicting the soil processes. The effects of three different landuse systems (cultivated land, fallow land and woodland) on soil compaction and infiltration rate were investigated at two sites of the study area. Site 1 represents the older one of the two. The soil penetration resistance (SPR) was measured in three depths using a manually operated cone penetrometer. Infiltration rate was measured in the field using a double-ring infiltrometer. Following the cone-penetrometer sampling, soil samples were collected to determine the variables that affect SPR and infiltration rate vs. particle size, dry BD, volumetric moisture content (VMC) and organic carbon (OC) content. Field measurements and soil samples were collected for each landuse type. The measured infiltration rate data were inserted into the Kostiakov Model in order to predict the cumulative soil water infiltration. Soil compaction for the cultivated land was 65 % larger in comparison to woodland. Woodland areas showed an increase in the infiltration rate by 87 % and 74 % compared to cultivated and fallow land respectively. Both study sites showed an increase in the dry BD when SPR is increasing, while VMC decreases with increasing SPR. Also, low OC contents were observed to be associated with high SPR values. For Site 1 the average coefficient of determination (R²) for the infiltration data fit to the Kostiakov Model were 0.65, 0.73 and 0.84 for cultivated land, fallow land and woodland respectively. However, for Site 2 they were 0.63, 0.76 and 0.78. In the Gadarif Region agriculture is the main activity and practised in many forms with a variety of environmental effects and consequences. Continuous ploughing of the cultivated land coupled with inproper soil management has contributed to soil deterioration when the landuse changed from woodland to cultivated and fallow land. Therefore, the development of sustainable landuse practises in the dryland-farming of the study area need to be improved in order to reduce the amount of soil degradation in the future
Mehrere Jahrzehnte intensiven Trockenfeldbaus in der Region von Gadarif, welche sich im östlichen Teil des Sudans befindet, führten hauptsächlich aufgrund von landwirtschaftlicher Expansion, politischen Beschlüssen der Regierung und Naturkatastrophen wie Trockenheit zu einer raschen Veränderung der Landnutzung und Landbedeckung. Das wesentliche Ziel dieser Dissertation war es, die Degradation des Landes, sowie die Auswirkungen von landwirtschaftlicher Expansion auf die Landbedeckung, den Boden und den Pflanzenbau im Untersuchungsgebiet, welches Teile der afrikanischen Sahelzone beinhaltet, abzuschätzen. Zur Analyse und Beobachtung der Veränderungen der Landnutzung und Landbedeckung wurden multi-temporale Landsat-Daten der Jahre 1979, 1989 und 1999 sowie ASTER-Daten aus dem Jahr 2009 genutzt, welche eine Fläche von schätzungsweise 1200 km² abdecken. Um Veränderungen von Landnutzung und Landbedeckung aus Satellitenbilddaten zu bestimmen, wurde ein auf Post-Klassifikation basierendes Vergleichsverfahren angewandt. Sechs Landnutzungs- und Landbedeckungsklassen, welche die Namen bewirtschaftetes Land, brach liegendes Land, Waldgebiet, Ödland, besiedeltes Land und Wasserfläche tragen, wurden während des Klassifikationsprozesses bestimmt. Für die vier Aufnahmezeitpunkte der Satellitendaten lag die allgemeine Klassifikationsgenauigkeit zwischen 86 % und 92 %. Während des dreißigjährigen Untersuchungszeitraums fand eine beträchtliche Veränderung der Landnutzungs- und Landbedeckungsstruktur statt. Bewirtschaftete Flächen nahmen in ihrem Anteil signifikant zu und bedeckten innerhalb des Zeitraums von 1979 bis 2009 81 % der früheren Waldgebiete. Der Anteil von brach liegendem Land nahm lediglich während des Zeitraums von 1989 bis 1999 zu. Besiedelte Gebiete breiteten sich über die drei Jahrzehnte kontinuierlich aus und wuchsen innerhalb des Zeitraums von 1979 bis 1989 um eine Fläche von 23 km², sowie um 21 km² zwischen 1989 und 1999 und um 27 km² in dem Zeitabschnitt 1999 – 2009. Eine detaillierte Karte zur Landnutzung und Landbedeckung des Untersuchungsgebiets wurde mittels der Nutzung dual polarisierter (HH und HV) TerraSAR-X Daten aus dem Jahr 2009 erzeugt. Die verschiedenen Landnutzungen und Landbedeckungen im Beobachtungsgelände wurden durch die Anwendung eines objektorientierten Klassifikationsansatzes analysiert. Um Bildobjekte zu erzeugen, wurde für diesen Zweck die auf einer mehrfachen Auflösung basierende Segmentierung der Software Definiens genutzt. Das Werkzeug Feature Space Optimisation wurde für die Optimierung der Attribute der TerraSAR-X Bilder angewandt, damit eine ideale Unterscheidungsfähigkeit entlang der Klassen für die Kartierung der Landnutzungen und Landbedeckungen erreicht werden kann. Zusätzlich zu jenen Klassen, welche mittels optischer Daten abgeleitet wurden, ergaben sich aus SAR-Daten noch die nachfolgenden Landnutzungen und Landbedeckungen: Abgeerntetes Land, Fels, Besiedlung 1 (Gebäude mit landestypischer Bedachung) und Besiedlung 2 (Gebäude mit Betondach). Die Koeffizienten der Rückstreuung entlang der Polarisationen HH und HV waren für einige Klassen unterschiedlich. Der günstigste Trennungsabstand der getesteten spektralen, formgebenden und texturalen Features ergab verschiedene Abweichungen zwischen den bestimmten Klassen der Landnutzung und Landbedeckung. Die Klassifikationsmaßnahmen ergaben eine Gesamtgenauigkeit von 84 % mit einem Kappa-Wert von 0.82. Genauigkeitsunterschiede entlang der Klassen wurden minimal gehalten. Seit über sechs Jahrzehnten wird in der Region Gadarif maschinenbetriebener Trockenfeldbau ausgeübt. In Folge dessen fand eine beträchtliche Abholzung und Überweidung sowie eine schwerwiegende Bodendegradation aufgrund des stetigen konventionellen Feldbaus statt. Um die Auswirkungen der Veränderung von Landnutzung und Landbedeckung auf die ausgewählten Bodenbeschaffenheiten auszuwerten, wurden drei Haupttypen der Landnutzung und Landbedeckung für die weitere Untersuchung ausgewählt: Bewirtschaftetes Land, brach liegendes Land, und Waldgebiet. Zusätzlich zu den Referenzbodenprofilen wurden außerdem für jeden Landnutzungs- und Landbedeckungstyp auf je zehn Probeflächen Bodenproben in zwei Tiefen entnommen. Bei diesen Bodenproben wurden zahlreiche Bodeneigenschaften analysiert, wie etwa Textur, Bodendichte (BD), organischer Materialgehalt (OM), pH-Wert des Bodens, elektrische Leitfähigkeit (EC), Adsorptionsgeschwindigkeit von Natrium (SoAR), Phosphorgehalt (P) sowie Kaliumgehalt (K). Labortests ergaben, dass die Bodeneigenschaften signifikant durch die Veränderungen der Landnutzung und Landbedeckung beeinflusst werden. Innerhalb der verschiedenen Landnutzungs- und Landbedeckungstypen variierte der Tongehalt in den Deckschichten (0 – 5 cm und 5 – 15 cm) zwischen 59 % und 65 %, wohin gegen sich die Lehmanteile von 27 % bis 37 % bewegten. Bodendichte, organischer Materialgehalt und Phosphorgehalt zeigten signifikant unterschiedliche Werte bei den drei Typen der Landnutzung und Landbedeckung (p < 0.05). Der pH-Wert des Bodens war signifikant verschieden zwischen bewirtschaftetem Land und Waldgebiet zum einen, und zwischen brach liegendem Land und Waldgebiet zum anderen. Die Werte der elektrischen Leitfähigkeit und der Adsorptionsgeschwindigkeit von Natrium bei brach liegendem Land erwiesen sich als maßgeblich verschieden zu jenen von Waldgebieten (p < 0.05). Auf dem Trockenland-Vertisolboden der Region Gadarif im Sudan wurde mehr als ein Drittel der nationalen Hirseproduktion erwirtschaftet – dem Haupternährungserzeugnis des Landes. Bodenverdichtung erwies sich als eines der weltweiten Hauptprobleme für den Pflanzenbau. Bodenfestigkeit und Versickerungsrate sind wichtige Variabeln, um Bodenprozesse verstehen und vorhersagen zu können. Die Auswirkungen der drei verschiedenen Landnutzungssysteme (bewirtschaftetes Land, brach liegendes Land und Waldgebiet) auf die Bodenverdichtung und Versickerungsrate wurden an zwei Standorten im Beobachtungsgebiet untersucht. Standort 1 ist der ältere der beiden. Der Widerstand der Bodenpenetration (SPR) wurde in drei Tiefen durch eine manuell angewandte Rammsonde gemessen. Mittels der Nutzung eines Doppelring-Infiltrometers ist die Versickerungsrate im Feld gemessen worden. Im Anschluss an die Probenentnahme mittels Rammsonden wurden Bodenproben gesammelt, um jene Variabeln bestimmen zu können, welche den Widerstand der Bodenpenetration sowie der Versickerungsrate im Vergleich zur Partikelgröße, zur trockenen Bodendichte, zum volumetrischen Feuchtigkeitsgehalt (VMC) und zum organischen Karbongehalt (OC) beeinflussen. Für jeden Landnutzungstypen wurden Feldmessungen durchgeführt und Bodenproben entnommen. Die gemessenen Daten der Versickerungsrate wurden in das Kostiakov-Modell eingespeist, um die gesamte Bodenwasserversickerung vorhersagen zu können. Die Bodenverdichtung bei bewirtschaftetem Land war 65 % stärker als bei Waldgebiet. Für Waldgebietsflächen wurde eine Zunahme der Versickerungsrate um 87 % verglichen mit bewirtschaftetem Land und um 74 % im Vergleich zu brach liegendem Land aufgezeigt. Beide Untersuchungsstandorte zeigten eine Zunahme in der trockenen Bodendichte für den Fall, dass der Widerstand der Bodenpenetration zunimmt, während der volumetrische Feuchtigkeitsgehalt mit zunehmendem Bodenpenetrationswiderstand abnimmt. Ebenso wurde beobachtet, dass ein geringer organischer Karbongehalt in Verbindung zu hohen Widerstandswerten der Bodenpenetration steht. Bei Standort 1 passte der durchschnittliche Bestimmungskoeffizient (R²) der Versickerungsrate zum Kostiakov-Modell mit den Werten 0.65 für bewirtschaftetes Land, 0.73 für brach liegendes Land und 0.84 für Waldgebiet. Für Standort 2 indessen ergaben die Werte 0.63, 0.76 und 0.78. Landwirtschaft, die in vielen Formen ausgeübt wird, ist die Haupttätigkeit in der Region Gadarif, und geht mit verschiedenartigsten Umweltauswirkungen und Konsequenzen einher. Kontinuierliche Feldbestellung des bewirtschafteten Landes, verbunden mit ungeeigneter Bodenbewirtschaftung, hat sich seit jenem Zeitpunkt, als sich die Landnutzung von Waldgebiet zu bewirtschaftetem und brach liegendem Land änderte, zu Bodenschädigung geführt. Daher muss die Entwicklung nachhaltiger Landnutzungspraktiken beim Trockenfeldbau im Untersuchungsgebiet verbessert werden, damit in Zukunft der Umfang der Bodendegradation verringert werden kann

Rolling dynamic compaction (RDC) consists of a non-circular module of 3, 4 or 5 sides, that rotates as it is towed, causing it to fall to the ground and compact it dynamically. There is currently little guidance available for geotechnical practitioners regarding the depths of improvement that are possible in varying soil conditions. Current practice dictates that practitioners rely on personal experiences or available published project case studies that are limited in scope and applicability as they are typically aimed at achieving a project specification. There is a reluctance to adopt RDC as a ground improvement technique as there is uncertainty regarding its limitations and capabilities. The underlying objective of this research is to quantify the ground response of the 8-tonne 4-sided impact roller. This research has used full-scale field trials and bespoke instrumentation to capture the ground response due to dynamic loading in homogeneous soil conditions. It was found that towing speed quantifiably influenced the energy imparted into the ground, with towing speeds of 10-12 km/h found to be optimal. Targeted full-scale field trials were undertaken to quantify the depth of improvement that can be achieved using RDC. Field results were compared to a number of published case studies that have used the 8-tonne 4-sided roller. Significantly, separate equations have been developed to allow practitioners to predict the depths that can be improved for the two major applications of RDC: improving ground in situ and compacting soil in thick layers. Finally, the in-ground response of RDC was measured using buried earth pressure cells (EPCs) and accelerometers. Force was determined from the measured change in stress recorded by EPCs whereas displacement was inferred from the double integration of acceleration-time data to give real-time load-displacement behaviour resulting from a single impact. The energy delivered to the soil by RDC is quantified in terms of the work done, defined as the area under the force versus displacement curve. Quantifying the energy imparted into the ground in terms of the work done is a key difference from past studies. Previous estimates of the energy delivered by impact roller at the ground surface has traditionally been predicted based on either gravitational potential energy (12 kJ) or kinetic energy (30 kJ to 54 kJ for typical towing speeds of 9 to 12 km/h). The two different values have caused confusion amongst practitioners. This research has determined that the maximum energy per impact that the 8-tonne 4-sided impact roller is capable of imparting to the ground is between 22 kJ to 30 kJ for typical towing speeds of 9 to 12 km/h. Quantifying the effectiveness of the 8-tonne 4-sided impact roller in terms of towing speed, depth of influence, and soil response measured via real-time measurements will lead to a greater understanding of the practical applications and limitations of RDC. Significantly, more accurate assessments of RDC will reduce design conservatism and construction costs, reduce instances where the predicted ground improvement does not occur and enable RDC to be used and applied with greater confidence.
Thesis (Ph.D.) -- University of Adelaide, School of Civil, Environmental and Mining Engineering, 2020

The use of impact rollers has increased for many decades over a wide variety of applications in various parts of the world. Many manufacturers have made claims that impact compaction rollers could have an effect to 1 m or more. In addition, other positive features such as greater depth of influence and faster travel speed than conventional rollers are being reported from the field. However, there is a lack of theoretical explanations or scientific research information for how to operate these rollers. Hence, this study will focus on a geotechnical modeling that describes the behavior of soils during ground compaction using various impact rollers (e.g., triangular, Landpac 3-sided, Landpac 5-sided, and octagonal shapes). In addition, this study will estimate more precisely the depth of influence for impact rollers. To do so, the general purpose finite element computer program LS-DYNA is used for numerical predictions. The finite element study is carried out with three-dimensional models. A simplified elastic perfectly plastic model with the Druker-Prager yield criterion is used for soil modeling and rollers are treated as a rigid body (i.e., incompressible material). The result of this study compares well with existing field experiment data for estimating vertical stress profile and compaction features, and demonstrates that the impact rollers are appropriate for thick layers.

碩士
逢甲大學
紡織工程學系
89
The impact performance of PP woven reinforced PP plates, manufactured by compression at different temperature and injection molding methods were compared in this study. Instrumented drop weight impact was used to perform the impact tests. The impact damage near the impact point was observed using a metallographic microscope. The experimental results showed that the delamination damage is the major mechanism for absorbing the impact energy in compression molding plate. The compression molding plates had higher energy absorption than injection molding plate, and had a optimal impact resistance at compression temperature of 170℃. The PP woven fabrics used in this study show α-form characteristics in DSC and WAXD analyses. The compression molding showed an increase of crystallinity and melting point with the heat treatment process, consequently the products exhibit higher mechanical properties.

Aubrey Berrangé, a South African roads engineer, invented the impact compactor in 1949 with the intention of achieving improved compaction to greater depths than possible with conventional equipment available at the time. The aim of this dissertation is to present a simple prediction model for the profile of improvement in the ground, using surface settlement as the main input parameter. The model is based on the information reviewed, observation of field data and a static numerical analysis. For simplicity sake, no attempt is made to predict the energy requirement to achieve the input value of settlement. The model is then verified on fifteen impact compaction profiles at six different sites. A 2 ton-meter dropping mass compactor was also used in the verification process with reasonable success. In addition, the model was tested against comprehensive testing performed at a dynamic compaction site with very promising results. The method is also shown to give acceptable results for prediction of density increase during a vibratory compaction trial. It is concluded that the improvement in the ground can be estimated with reasonable success if the surface settlement is monitored, providing strains are taken into account.
Dissertation (MEng (Geotechnical Engineering))--University of Pretoria, 2006.
Civil Engineering
unrestricted

The dissertation thesis deals with the evaluation of the influence of the movements of the mechanization devices on soil compaction in grassed and cultivated vineyard between the lines after application of graded doses of organic matter (compost). This question was verified using penetrometer measurements. For the purpose of experimentation were selected in the vineyard region of South Moravia three experimental habitats with different soil conditions (Lednice, Velké Bílovice, Mikulov). In the autumn of 2013, the application of compost to the cultivated intercooler took place in doses of 5 and 10 kg.m-2. Penetrations measurements for each experimental site were carried out in four variants (grassed between the lines, cultivated between the lines, cultivated between the lines with application of 5 kg.m-2 and cultivated between the lines with application of 10 kg.m-2). Individual measurements were performed using a Eijelkamp penetrometer, which works at an accuracy of 99.9 % and its working depth is 800 mm. At the same time, soil samples were removed to determine the current soil moisture. Based on the measurements, high values of soil compaction were found for all monitored habitats. At the same time, the positive effect of the organic mass produced in the form of compost on the total soil compaction was demonstrated, which was 20 % lower in autumn 2016 than in the autumn of 2013. The worst was the period of spring 2014 and autumn 2015. The highest values of penetrometric resistance of the soil were measured from the rule for grassed between the lines. On the contrary, the lowest values were measured for the variant of the cultivated between the lines with the application of 10 kg.m-2. The parts of the dissertation are also the results of the evaluation of pressure transmissions using the TASC program and the results of the tire imprint.

Soil compaction caused by heavy play is a serious problem in golf course as it affects nearly all properties and functions of soil, physical, chemical as well as biological, which in turn cerate irrigation and drainage problems and influence the healthy growth of turfgrass. However, knowledge regarding the interactive effects of play intensity and soil moisture status on irrigation, drainage and turfgrass growth is still lacking. The objectives of this study are to examine the interactive effects of play intensity and soil moisture levels on some important irrigation and drainage parameters and turfgrass growth, and to evaluate the impact of soil compaction on water quality in terms of nitrate concentration. A green house study was carried out under simulated soil compaction on golf course fairway. Three play intensity level treatments and three soil moisture level treatments were tested. The results showed that the state of soil compaction not only is largely influenced by traffic intensity, but also is closely related to soil water content. Hence control of traffic and soil moisture is equally important for minimizing soil compaction. This investigation clearly demonstrated that soil compaction significantly changes the soil hydraulic properties, the infiltration, hydraulic conductivity and drainable porosity, and has adverse effects on irrigation and drainage. Both shoot and root growth declined as a result of soil compaction. It was observed that root biomass of turfgrass was reduced by as much as 47 to 75 percent under soil compaction condition when compared to non-compaction. Soil compaction is very detrimental to root growth. The study revealed that favorable soil water content for turfgrass shoot growth depends on traffic intensity. For heavy play golf course, maintaining adequate low soil moisture is more favorable to turfgrass growth. This study found that N0₃⁻ concentration in leachate increased as a result of soil compaction. However, the detected N0₃⁻ concentration under soil compaction was still extremely low, well below the drink water requirement.

碩士
朝陽科技大學
營建工程系碩士班
93
The quality of “compaction” is a conclusive factor to the quality of an embankment project. Compaction of an embankment aims at (1) to increase the shearing strength for improving the bearing capacity of foundation and/or the stability of side slope of embankment, (2) to reduce the compressibility (consolidation settlement) for decreasing future settlement, on account of minimizing or preventing occurrence of hazardous settlement，(3) to decrease the permeability for improving the imperviousness. The purpose of study is to examine a method of measuring the velocities of P-wave and S-wave by an Impact-Echo method to evaluate the compacted conditions of the embankment, including the relationship between the velocities of P-wave and S-wave and the density, water content, and CBR, on account of evaluating the possibility of replacing the labor and time consuming Sand-Cone method or the dangerous nuclear method with the Impact-Echo method in measuring field densities and moisture contents. The materials used in the study of this thesis are the contact clay, and the core and shell materials to be placed in the PaoShan Second Reservoir Project. The engineering properties of these materials are quite different mutually. Performing P-wave and S-wave velocity measurement, and tests of density, moisture content and CBR, in expectation of being able to find out some relationship among these test data. From this study, the following have been found：(1) As the compacted dry density of the embankment increases gradually, the velocities of P-wave and S-wave also increase gradually. Higher the compacted dry density, faster the P-wave and S-wave velocities become. Up until the compacted dry density approaching the maximum, the wave velocities start to decrease in reverse. When the compacted dry density begins to decrease, the wave velocities decrease significantly； (2) P-wave and S-wave velocities decrease sharply as the water content increase gradually；(3) Under a fixed water content, following gradual increase of compacted dry density, the p- and s- velocities of the embankment increase. However, for overly high water content, the wave velocities become unstable and the relationship between the wave velocities and the compacted dry density is indistinct；(4) the relationship between the wave velocities and the CBR indicates that the wave velocities have a tendency to increase following the CBR value increase；(5) The CBR value has the tendency of increase proportionally with the elastic modulus obtained from the wet density, and speeds of P and S waves. Thus, with correct measurement of P and S-wave, it is possible to evaluate the bearing capacity of soil in field via the calculated elastic modulus.

Several decades of intensive dryland-farming in the Gadarif Region, located in the Eastern part of Sudan, has led to rapid landuse/landcover (LULC) changes mainly due to agricultural expansion, government policies and environmental calamities such as drought. The study area represents part of the African Sahel. The fundamental goal of the thesis was to assess land degradation and the impact of agriculture expansion on land cover, soil and crops production. To analyse and to monitor the LULC changes, multi-temporal Landsat data of the years 1979, 1989 and 1999 and ASTER data of the year 2009 covering an area of approximately 1200 km² were used. For this a post-classification comparison technique was applied to detect LULC changes from satellite images. Six LULC classes were identified during the classification scheme, namely cultivated land, fallow land, woodland, bare land, settlement and water. For the four dates of satellite images the overall classification accuracy ranged from 86 % to 92 %. During the three decades of the study period an extensive change of LULC patterns occurred. The cultivated areas increased significantly, covering 81 % of the previous woodland in the period 1979 – 2009. Fallow land only increased during the period 1989 – 1999. Over the three decades, urban expansion continuously increased covering an area of 23, 21 and 27 km² for the periods 1979 – 1989, 1989 – 1999 and 1999 – 2009 respectively. The detailed LULC map of the study area was obtained by using a dual polarisation (HH and HV) TerraSAR-X data of the year 2009. The different LULCs of the study area were analysed by employing an object-oriented classification approach. For that purpose, multi-resolution segmentation of the Definiens Software was used for creating the image objects. Using the feature-space optimisation tool the attributes of the TerraSAR-X images were optimised in order to obtain the best separability among classes for the LULC mapping. In addition to the classes that have been obtained by the optical data, the following LULCs resulted from SAR data: harvested land, rock, settlement 1 (local-roof buildings) and settlement 2 (concrete roof buildings). The backscattering coefficients for some classes were different along HH and HV polarisation. The best separation distance of the tested spectral, shape and textural features showed different variations among the discriminated LULC classes. An overall accuracy of 84 % with a kappa value of 0.82 was resulted from the classification scheme. Accuracy differences among the classes were kept minimal. For more than six decades in the Gadarif Region mechanised dryland farming is practised. As a result, due to continuous conventional tillage, extensive woodcutting and over-grazing, serious soil degradation occurred. To discuss the impact of LULC changes on the selected soil properties, three main LULC types were chosen to be investigated, namely: cultivated land, fallow land and woodland. In addition to the reference soil profiles, soil samples were also collected at two depths from ten sample plots for each of the LULC type. For these soil samples, various soil properties such as texture, bulk density (BD), organic matter (OM), soil pH, electrical conductivity (EC), sodium adsorption ratio (SoAR), phosphorous (P) and potassium (K) were analysed. Laboratory tests proved that soil properties were significantly affected by LULC changes. Within the different LULC types, clay content in the surface layers (0 – 5 and 5 – 15 cm) varied from 59 % to 65 %, whereas silt fractions ranged from 27 % to 37 %. Soil BD, OM and P were significantly different (p < 0·05) across the three LULC types. Soil pH was significantly different between cultivated land and woodland on one side and between fallow land and woodland on the other side. EC and SoAR values of fallow land were found to be significantly different (p < 0·05) from woodland. The dryland vertisol of the Gadarif Region in Sudan produced more than one-third of the national production of sorghum – the main food stuff in the country. Soil compaction has been recognised as one of the major problems in crop production worldwide. Soil strength and infiltration rate are important variables for understanding and predicting the soil processes. The effects of three different landuse systems (cultivated land, fallow land and woodland) on soil compaction and infiltration rate were investigated at two sites of the study area. Site 1 represents the older one of the two. The soil penetration resistance (SPR) was measured in three depths using a manually operated cone penetrometer. Infiltration rate was measured in the field using a double-ring infiltrometer. Following the cone-penetrometer sampling, soil samples were collected to determine the variables that affect SPR and infiltration rate vs. particle size, dry BD, volumetric moisture content (VMC) and organic carbon (OC) content. Field measurements and soil samples were collected for each landuse type. The measured infiltration rate data were inserted into the Kostiakov Model in order to predict the cumulative soil water infiltration. Soil compaction for the cultivated land was 65 % larger in comparison to woodland. Woodland areas showed an increase in the infiltration rate by 87 % and 74 % compared to cultivated and fallow land respectively. Both study sites showed an increase in the dry BD when SPR is increasing, while VMC decreases with increasing SPR. Also, low OC contents were observed to be associated with high SPR values. For Site 1 the average coefficient of determination (R²) for the infiltration data fit to the Kostiakov Model were 0.65, 0.73 and 0.84 for cultivated land, fallow land and woodland respectively. However, for Site 2 they were 0.63, 0.76 and 0.78. In the Gadarif Region agriculture is the main activity and practised in many forms with a variety of environmental effects and consequences. Continuous ploughing of the cultivated land coupled with inproper soil management has contributed to soil deterioration when the landuse changed from woodland to cultivated and fallow land. Therefore, the development of sustainable landuse practises in the dryland-farming of the study area need to be improved in order to reduce the amount of soil degradation in the future.
Mehrere Jahrzehnte intensiven Trockenfeldbaus in der Region von Gadarif, welche sich im östlichen Teil des Sudans befindet, führten hauptsächlich aufgrund von landwirtschaftlicher Expansion, politischen Beschlüssen der Regierung und Naturkatastrophen wie Trockenheit zu einer raschen Veränderung der Landnutzung und Landbedeckung. Das wesentliche Ziel dieser Dissertation war es, die Degradation des Landes, sowie die Auswirkungen von landwirtschaftlicher Expansion auf die Landbedeckung, den Boden und den Pflanzenbau im Untersuchungsgebiet, welches Teile der afrikanischen Sahelzone beinhaltet, abzuschätzen. Zur Analyse und Beobachtung der Veränderungen der Landnutzung und Landbedeckung wurden multi-temporale Landsat-Daten der Jahre 1979, 1989 und 1999 sowie ASTER-Daten aus dem Jahr 2009 genutzt, welche eine Fläche von schätzungsweise 1200 km² abdecken. Um Veränderungen von Landnutzung und Landbedeckung aus Satellitenbilddaten zu bestimmen, wurde ein auf Post-Klassifikation basierendes Vergleichsverfahren angewandt. Sechs Landnutzungs- und Landbedeckungsklassen, welche die Namen bewirtschaftetes Land, brach liegendes Land, Waldgebiet, Ödland, besiedeltes Land und Wasserfläche tragen, wurden während des Klassifikationsprozesses bestimmt. Für die vier Aufnahmezeitpunkte der Satellitendaten lag die allgemeine Klassifikationsgenauigkeit zwischen 86 % und 92 %. Während des dreißigjährigen Untersuchungszeitraums fand eine beträchtliche Veränderung der Landnutzungs- und Landbedeckungsstruktur statt. Bewirtschaftete Flächen nahmen in ihrem Anteil signifikant zu und bedeckten innerhalb des Zeitraums von 1979 bis 2009 81 % der früheren Waldgebiete. Der Anteil von brach liegendem Land nahm lediglich während des Zeitraums von 1989 bis 1999 zu. Besiedelte Gebiete breiteten sich über die drei Jahrzehnte kontinuierlich aus und wuchsen innerhalb des Zeitraums von 1979 bis 1989 um eine Fläche von 23 km², sowie um 21 km² zwischen 1989 und 1999 und um 27 km² in dem Zeitabschnitt 1999 – 2009. Eine detaillierte Karte zur Landnutzung und Landbedeckung des Untersuchungsgebiets wurde mittels der Nutzung dual polarisierter (HH und HV) TerraSAR-X Daten aus dem Jahr 2009 erzeugt. Die verschiedenen Landnutzungen und Landbedeckungen im Beobachtungsgelände wurden durch die Anwendung eines objektorientierten Klassifikationsansatzes analysiert. Um Bildobjekte zu erzeugen, wurde für diesen Zweck die auf einer mehrfachen Auflösung basierende Segmentierung der Software Definiens genutzt. Das Werkzeug Feature Space Optimisation wurde für die Optimierung der Attribute der TerraSAR-X Bilder angewandt, damit eine ideale Unterscheidungsfähigkeit entlang der Klassen für die Kartierung der Landnutzungen und Landbedeckungen erreicht werden kann. Zusätzlich zu jenen Klassen, welche mittels optischer Daten abgeleitet wurden, ergaben sich aus SAR-Daten noch die nachfolgenden Landnutzungen und Landbedeckungen: Abgeerntetes Land, Fels, Besiedlung 1 (Gebäude mit landestypischer Bedachung) und Besiedlung 2 (Gebäude mit Betondach). Die Koeffizienten der Rückstreuung entlang der Polarisationen HH und HV waren für einige Klassen unterschiedlich. Der günstigste Trennungsabstand der getesteten spektralen, formgebenden und texturalen Features ergab verschiedene Abweichungen zwischen den bestimmten Klassen der Landnutzung und Landbedeckung. Die Klassifikationsmaßnahmen ergaben eine Gesamtgenauigkeit von 84 % mit einem Kappa-Wert von 0.82. Genauigkeitsunterschiede entlang der Klassen wurden minimal gehalten. Seit über sechs Jahrzehnten wird in der Region Gadarif maschinenbetriebener Trockenfeldbau ausgeübt. In Folge dessen fand eine beträchtliche Abholzung und Überweidung sowie eine schwerwiegende Bodendegradation aufgrund des stetigen konventionellen Feldbaus statt. Um die Auswirkungen der Veränderung von Landnutzung und Landbedeckung auf die ausgewählten Bodenbeschaffenheiten auszuwerten, wurden drei Haupttypen der Landnutzung und Landbedeckung für die weitere Untersuchung ausgewählt: Bewirtschaftetes Land, brach liegendes Land, und Waldgebiet. Zusätzlich zu den Referenzbodenprofilen wurden außerdem für jeden Landnutzungs- und Landbedeckungstyp auf je zehn Probeflächen Bodenproben in zwei Tiefen entnommen. Bei diesen Bodenproben wurden zahlreiche Bodeneigenschaften analysiert, wie etwa Textur, Bodendichte (BD), organischer Materialgehalt (OM), pH-Wert des Bodens, elektrische Leitfähigkeit (EC), Adsorptionsgeschwindigkeit von Natrium (SoAR), Phosphorgehalt (P) sowie Kaliumgehalt (K). Labortests ergaben, dass die Bodeneigenschaften signifikant durch die Veränderungen der Landnutzung und Landbedeckung beeinflusst werden. Innerhalb der verschiedenen Landnutzungs- und Landbedeckungstypen variierte der Tongehalt in den Deckschichten (0 – 5 cm und 5 – 15 cm) zwischen 59 % und 65 %, wohin gegen sich die Lehmanteile von 27 % bis 37 % bewegten. Bodendichte, organischer Materialgehalt und Phosphorgehalt zeigten signifikant unterschiedliche Werte bei den drei Typen der Landnutzung und Landbedeckung (p < 0.05). Der pH-Wert des Bodens war signifikant verschieden zwischen bewirtschaftetem Land und Waldgebiet zum einen, und zwischen brach liegendem Land und Waldgebiet zum anderen. Die Werte der elektrischen Leitfähigkeit und der Adsorptionsgeschwindigkeit von Natrium bei brach liegendem Land erwiesen sich als maßgeblich verschieden zu jenen von Waldgebieten (p < 0.05). Auf dem Trockenland-Vertisolboden der Region Gadarif im Sudan wurde mehr als ein Drittel der nationalen Hirseproduktion erwirtschaftet – dem Haupternährungserzeugnis des Landes. Bodenverdichtung erwies sich als eines der weltweiten Hauptprobleme für den Pflanzenbau. Bodenfestigkeit und Versickerungsrate sind wichtige Variabeln, um Bodenprozesse verstehen und vorhersagen zu können. Die Auswirkungen der drei verschiedenen Landnutzungssysteme (bewirtschaftetes Land, brach liegendes Land und Waldgebiet) auf die Bodenverdichtung und Versickerungsrate wurden an zwei Standorten im Beobachtungsgebiet untersucht. Standort 1 ist der ältere der beiden. Der Widerstand der Bodenpenetration (SPR) wurde in drei Tiefen durch eine manuell angewandte Rammsonde gemessen. Mittels der Nutzung eines Doppelring-Infiltrometers ist die Versickerungsrate im Feld gemessen worden. Im Anschluss an die Probenentnahme mittels Rammsonden wurden Bodenproben gesammelt, um jene Variabeln bestimmen zu können, welche den Widerstand der Bodenpenetration sowie der Versickerungsrate im Vergleich zur Partikelgröße, zur trockenen Bodendichte, zum volumetrischen Feuchtigkeitsgehalt (VMC) und zum organischen Karbongehalt (OC) beeinflussen. Für jeden Landnutzungstypen wurden Feldmessungen durchgeführt und Bodenproben entnommen. Die gemessenen Daten der Versickerungsrate wurden in das Kostiakov-Modell eingespeist, um die gesamte Bodenwasserversickerung vorhersagen zu können. Die Bodenverdichtung bei bewirtschaftetem Land war 65 % stärker als bei Waldgebiet. Für Waldgebietsflächen wurde eine Zunahme der Versickerungsrate um 87 % verglichen mit bewirtschaftetem Land und um 74 % im Vergleich zu brach liegendem Land aufgezeigt. Beide Untersuchungsstandorte zeigten eine Zunahme in der trockenen Bodendichte für den Fall, dass der Widerstand der Bodenpenetration zunimmt, während der volumetrische Feuchtigkeitsgehalt mit zunehmendem Bodenpenetrationswiderstand abnimmt. Ebenso wurde beobachtet, dass ein geringer organischer Karbongehalt in Verbindung zu hohen Widerstandswerten der Bodenpenetration steht. Bei Standort 1 passte der durchschnittliche Bestimmungskoeffizient (R²) der Versickerungsrate zum Kostiakov-Modell mit den Werten 0.65 für bewirtschaftetes Land, 0.73 für brach liegendes Land und 0.84 für Waldgebiet. Für Standort 2 indessen ergaben die Werte 0.63, 0.76 und 0.78. Landwirtschaft, die in vielen Formen ausgeübt wird, ist die Haupttätigkeit in der Region Gadarif, und geht mit verschiedenartigsten Umweltauswirkungen und Konsequenzen einher. Kontinuierliche Feldbestellung des bewirtschafteten Landes, verbunden mit ungeeigneter Bodenbewirtschaftung, hat sich seit jenem Zeitpunkt, als sich die Landnutzung von Waldgebiet zu bewirtschaftetem und brach liegendem Land änderte, zu Bodenschädigung geführt. Daher muss die Entwicklung nachhaltiger Landnutzungspraktiken beim Trockenfeldbau im Untersuchungsgebiet verbessert werden, damit in Zukunft der Umfang der Bodendegradation verringert werden kann.