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Yes / This paper presents the results of laboratory experiments and numerical simulations to investigate the effect of different piggyback pipeline configuration on the morphology of local seabed scour subject to steady currents. Piggyback pipeline configuration investigated includes the commonly used piggyback pipeline, namely a small pipe attached on the top of large pipe and new form of piggyback pipeline proposed in this study in which a small pipe is attached to the large pipe on the upstream and downstream side, respectively. Pressure gradient, drag coefficient, lift coefficient and scour extent around pipelines are measured and analyzed for a range of pipelines and current conditions. Results show that the vortex strength downstream of the commonly used piggyback pipeline is larger than that for a single as well as the new piggyback pipeline under the same condition. This new type piggyback pipeline can effectively reduce the depth and width of the scour hole. In particular, when the ratio of the small pipe diameter over the large pipe diameter is greater than 0.3, little scour under this new type piggyback pipeline occurs for the test conditions. The bed topography downstream of the pipe has also been altered to favor the backfill. / National Natural Science Foundation of China (No. 51279189).

Nine 1B/1R translocated soft red winter wheat (SRWW) varieties and six non-1B/1R varieties from two crop years (1995-1996 and 1996-1997), grown in two Virginia locations (Warsaw and Blacksburg), were studied to evaluate the effects of the 1R rye chromosome on soft wheat flour quality and baking performance. The presence of the 1B/1R chromosomal translocation in wheat has been reported to provide disease resistance, but produce sticky doughs. The 1995-1996 and 1996-1997 SRWW flours were subjected to farinograph analysis and dough stickiness testing. Dough stickiness was determined by the Schwarzlaff-Shepherd Dough Stripping Method. Wheat samples from 1995-1996 were also analyzed for protein, ash, and moisture content, alkaline water retention capacity (AWRC), cookie diameter, tensile stress and strain, and by ¹³C nuclear magnetic resonance (¹³C-NMR) spectroscopy techniques. Significant (p = 0.0001) negative correlations were found between AWRC and cookie diameter of SRWWs grown in Warsaw and Blacksburg. Location was found to exert a significant effect on AWRC, cookie diameter and stickiness (p < 0.05). Farinograph data revealed that mixing characteristics of SRWW were affected significantly by variety, crop year and location (p < 0.05). In some cases the 1B/1R varieties had lower breakdown rates, longer departure times (DT) and lower mixing tolerance index (MTI), than their non-1B/1R counterparts. There was a significant difference (p = 0.0133) in the stickiness of 1B/1R and non-1B/1R samples from Blacksburg. However no such difference was found in the corresponding Warsaw samples (p = 0.9826), indicating that location exerted a significant effect on stickiness. Two flour samples exhibiting stickiness (one with and one without 1B/1R) and two non-sticky samples (one with and one without the 1B/1R) were fractionated into gluten, starch and water-solubles (WS) in order to determine if the sticky dough factor resided in the 1B/1R and / or non-1B/1R WS. The peel time of the interchanged samples, as in the case of 'Massey' flour combined with the WS from VA52-22, increased to 79 seconds from the 30 seconds originally observed in the Massey flour. However when gluten and starch fractions from a non-sticky, non-1B/1R sample,VA54-21, were mixed with WS from VA54-211 (sticky, 1B/1R), the peel time went from 18 in the original flour to 8 seconds. Tensile measurements showed dough stress was not significantly affected by the presence or absence of 1B/1R (p = 0.7057). However, dough strain was lower in 1B/1R translocated SRWWs (p = 0.0048). A ¹³C-NMR spectra failed to show differences amongst selected 1B/1R and non-1B/1R dough samples. Proton relaxation time (T1-rho-[H]) - a ¹³C-NMR technique, indicated that water did not exert a significant influence on the molecular dynamics within the dough samples of Massey (non-1B/1R), VA54-211 (1B/1R) and VA52-22 (1B/1R). However, the non-sticky, non-1B/1R sample (VA54-21) had a higher proton relaxation time at 62 ppm which may indicate the size of starch-protein particles in VA54-21 doughs were larger and less flexible than in the other three doughs. / Ph. D.

This study compared the effects of selective cutting (SC) and the first shelterwood (SW) cut in oak (Quercus)-dominated forests of western Virginia. The specific attributes compared were: (1) tree species composition; (2) seedling, sapling, and overstory tree density; (3) overstory tree quality and size; (4) sapling crown class; and (5) canopy closure. Seedlings, saplings, and overstory trees were sampled at 22 SC and 28 SW sites. Significant differences identified between the two harvest types included: biodiversity of overstory and seedling layers; species densities for seedlings, saplings, and overstory trees; species composition across forest layers; and average canopy closure. Regeneration was poorer on SC than on SW, especially among oak species where SC oak seedling density averaged 5,651 stems ha-1 and SW oak seedling density averaged 9,843 stems ha-1. Selective cutting and SW may both contribute to mesophication of oak-dominated forests in the southern Appalachian Mountains; however, SC resulted in a higher percentage of mesic species post-harvest, and the SW tended to have more oak regeneration. / Master of Science / Selective cutting in the form of high-grading (harvesting only the most valuable trees in a forest) and diameter-limit cutting (harvesting all merchantable trees in a forest above a designated diameter at breast height) is the predominant timber harvest practice in the southern Appalachian Mountains. It is contributing to a shift in forest composition away from oak species toward tree species of lower commercial and wildlife value. In this study, although there were fewer seedlings and saplings after selective cuts than after shelterwoods (a partial harvest of trees aimed at encouraging the regeneration of desirable tree species such as oaks in the future forest), there was higher tree species diversity among the seedlings and saplings at selective cutting sites than at shelterwoods. Oak regeneration remains a challenging goal to meet, but silvicultural systems such as shelterwoods that are designed to promote oak regeneration are likely to be more successful than selective cutting at maintaining oak dominance in this forested region.

A method is set forth which makes use of a commercially available, non-metric, solid-state matrix camera to capture spatial and spectral data from an individual tree bole that can be used to measure characteristics about the stem. In this study diameters and heights were measured and used to estimate the volume of 20 red oak (Quercus spp.) stems ranging in diameter at breast height from 16 to over 60 cm and height from 12 to 20 meters. Images were taken from four orthogonal directions around the each stem. Diameter estimates from matching camera to stem distances (3 to 15 meters) of opposite sides were arithmetically averaged. Two arithmetic averages from perpendicular directions were then geometrically averaged. It was found that locating the camera farther from the tree led to more consistent results over the entire stem while locating it closer to the tree provided the most precise estimates provided the inclination angle did not exceed 45 degrees. This method resulted in geometric mean diameter estimates within ± 4 cm for all heights combined when obtained at a distance of 12 m or greater using a 95 % chi-square maximum anticipated error statistic. Error increases with increased stem height from ± 3 cm to ± 7 cm for heights from 1 to 20 meters. In general, the error is equivalent to 3 times the instrument precision, which varies with distance. Two-thirds of the time volume estimates were within 8 percent, which is quite an improvement over the 30 percent interval afforded by an appropriate volume equation. / Master of Science

With the advent of the large diameter tunnel boring machine (TBM), mechanically driven large diameter tunnel is becoming a more attractive option. During operation, a large diameter tube allows for stacked deck configuration with shafts dropped to platform level (no station caverns). The extensive information has been compiled on innovative TBM tunneling projects such as the Barcelona Line 9, where the concept of continuous station has been used for the first time, stormwater management and roadway tunnel in Malaysia, where the floodwater bypass tunnel and the road tunnel are incorporated in a single bore tunnel. The decision making process that led to the construction of large bore tunnel is also presented. A detailed study has been carried out to determine the necessary face support pressure in drained conditions (with ideal membrane), and undrained conditions. The effects of tunnel diameter, cover-to-diameter ratio, at-rest lateral earth pressure coefficient, and soil shear strength parameters on the local and global stability of the excavation face of mechanically-driven tunnels have been investigated. The relation between the face support pressure and the calculated tunnel face displacement gave the minimum face support pressure that should be applied on the tunnel face to avoid abrupt movement of the tunnel face. Simple expressions have been developed for the support pressure as a function of tunnel diameter, cover depth, lateral earth pressure coefficient, and soil strength parameters. The required face support pressures are compared to the analytical solutions available from the literature. It has been found that analytical stability solutions generally underestimate the required face support pressure and excessive deformation will take place in the ground near the tunnel heading when these solutions are used. By using plastic limit analysis, a rigid and deformable prism-and-wedge model has been developed; in undrained conditions, upper bound solutions against collapse load are derived for face pressure. Deformable blocks enabled to take into account the effect of non-uniform support pressure due to the unit weight of the supporting medium. The upper bound solution derived as a function of tunnel diameter and cover depth, normalized undrained shear strength ratio, and unit weight of the ground and the supporting medium was compared with a solution available from the literature. Largest face support pressure was obtained when the uniform face support pressure was applied and it was smallest when identical unit weight was used for the ground and the supporting medium. / text

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Savanna woodlands are vitally important in providing ecological services (e.g. erosion protection, micro-climate) and economic services (e.g. timber, food, fodder non-wood products, and wild-life habitats) that sustain local livelihoods and national economies. Increasing demands and the need for sustainable savanna woodland resource management requires that the ecological, economic, social and cultural values of these resources be explored and brought to the attention of decision makers and the general public. The identification and better understanding of the structure and dynamics of woodland community types, patterns of species distribution and quantitative properties of their diversity is important to the conservation and sustainable management of these woodlands. This study seeks to contribute to a better understanding of Nakasongola woodland community types, species diversity patterns and environment correlates, natural regeneration processes (i.e. sprouting and seedling establishment) and identifying livelihood strategies adopted by households, woody species utilised, and the contribution of charcoal production to household livelihoods. Data on vegetation and environmental variables were collected using 75 rectangular 20 x 50 m (0.1 ha) plots. Data on land use and land cover changes, and relevant associated socio-economic parameters were collected through the analysis of multi-temporal satellite imagery and field observations, as well as interviews of local households and key informants. The basic major livelihood activities for the rural households in this savanna dryland are charcoal production, subsistence crop cultivation and livestock grazing. However, it, sometimes, includes various combinations of activities, i.e. charcoal production and subsistence crop cultivation for both food and cash, and livestock keeping for income generation through selling the livestock products such as milk and, sometimes, the whole animal. At least 24 woody species, including fruit trees (Mangifera indica and Artocarpus heterophyllus), are frequently harvested, including 16 species that are considered the most utilized for charcoal production. Charcoal production, being the major source of income to the rural households, contributes on average US$ 259 ± 46 (S.E.) per household annually. There were significant differences in charcoal production (Kruskal-Wallis; H = 31.42, p < 0.0001), producer sale prices per bag of charcoal (H = 35.62, p < 0.0001), and annual incomes from charcoal production (H = 32.44, p < 0.0001) per households across the 8 sub-counties. Most of the youth (≤ 20 years old) derive their livelihoods from charcoal production, a small amount of trade, offering labour services, livestock keeping, fishing, bee keeping and earth brick making. Charcoal production, livestock keeping and hunting are carried out particularly by men, whereas, crop cultivation, and collection of fire wood, medicinal plants and fruits are carried out, mainly, by women. However, men are also engaged in cultivation only during the rainy seasons. There have been significant land cover changes in the area during the period 1984 to 2001, resulting in a 64% decrease in dense woodland cover, and an 80% increase in areas under cultivation/settlements. These changes are attributed to significant spatial expansion in agriculture increased commercialisation of charcoal production, grazing and human population growth. A total of 44,195 (5,893 plants/ha) woody plants representing 99 species in 67 genera and 31 families were recorded. The most species rich families were Mimosaceae (13), Rubiaceae (9), Moraceae (7), Euphorbiaceae (7), Anacardiaceae (6), Combretaceae (5) and Verbenaceae (5). Density of woody species differed significantly (F2, 72 = 6.3, P < 0.003) among land uses, being higher under charcoal production (7,131 ± 755 plants/ha) and cultivation (6,612 ± 665) areas and significantly lower under grazing lands (4,152 ± 525). Community species composition differed significantly (Global RANOSIM = 0.14, p = 0.001) among land use types. All measures of beta-diversity (spatial “turnover” in species composition) showed consistently higher beta-diversity in the grazing land use (βW = 3.1; βT = 3.1), followed by cultivation (βW = 2.8; βT = 3.0) and charcoal production (βW = 2.7; βT = 2.8), suggesting a more heterogeneous spatial distribution of species in the grazing lands. This suggests that variations in the composition and diversity of woody species are to a great extent influenced by land use type and anthropogenic disturbances in this region. Basal area of woody species differed significantly (F2, 72 = 12.0, P < 0.0001) among land uses, being highest under cultivation and charcoal production and significantly lower under grazing. Woody plant density differed (F2,72 = 6.3, P = 0.003) across landuses, being highest under charcoal production and cultivation and significantly lower under grazing. The species that contributed most to both basal area and density across all the land uses were Combretum collinum and Combretum molle. However, different species contributed the next most i.e. Piliostigma thonningii for grazing; Albizia zygia and Harrisonia abyssinica for cultivation and Vepris nobilis for charcoal production areas. For both basal area and abundance of all woody species, the total variance in species-environmental factor relations (for the combined first four canonical axes) was higher than 50%, suggesting a relatively strong influence of the measured environment variables on species composition and distributions. The CCA points to a significant influence of soil Ca2+ and Mg2+ in association with grazing on gradients in the composition and structure of woody species in the savanna woodland of Nakasongola. Resprouting was generally common among the woody species. A total of 2,595 stumps, representing 74 species in 31 families were recorded from all plots. Of these, 98.3% resprouted and were identified to species level. Density of both stumps and total resprout differed significantly (p < 0.05) among the land uses, being higher in charcoal production areas than in grazing and cultivation land uses. For the overall pooled data, resprouts per stump differed significantly among land uses (F2, 456 = 7.75, p = 0.0005), being highest in charcoal production (mean ± S.E.; 14 ± 1) and cultivation (13 ± 1) land uses and lowest under grazing areas (10 ± 1). Generally, the mean number of resprouts per stump increased with increasing stump basal diameter (BD), being highest for BD size class > 41 cm. In relation to stump height, the highest mean resprouts/stump was found on stumps with heights ranging from 0.31- 0.40 m. Based on pooled species data, regression analyses showed weakly significant negative relationships between BD of leading resprouts and number of resprouts/stump (r2 = 0.123, p < 0.0001) and between height of leading resprouts and number of resprouts/stump (r2 = 0.068, p < 0.0001). Density of seedlings of woody species differed significantly among land use types (ANOVA; F2, 72 =5.9, p = 0.004), being highest for cultivation (3,162 ± 440 individuals ha-1), followed by charcoal production (2,416 ± 295 ha-1) and lowest for grazing (1,629 ± 205 ha-1). Composition of seedlings differed significantly among land use types (Global RANOSIM = 0.119, p = 0.001). The distributions and densities of some seedlings were explained by gradients in environmental variables, with edaphic factors (i.e. Ca2+, Mg2+, K+ and organic matter) and charcoal production being the most important. The first two axes of the Canonical Correspondence Analysis (CCA) explained 41.9% of the variance in species – environmental relations and were a reflection of edaphic and charcoal production land use gradients. All of the 16 highly utilized species were well represented in both the juvenile and adult classes, with gradually declining number of individuals with increasing stem size-class. This indicates that most of these species have high regeneration potential. Juvenile:adult tree ratios >1 and negative DSCD slopes indicate good recruitment and probably successful regeneration for these species. The study revealed land cover changes mainly in the dense and medium dense woodlands, reflected by the increase in open woodland, grasslands and cultivation/settlements. These trends threaten the livelihoods of local communities who are entirely dependent on these natural resources. Sustainable management will require the establishment of suitable integrated community-based institutions and management practices, with support from all key stakeholders (i.e. National Forest Authority (NFA)) and local communities. Maintenance of savanna woodland resources and other ecosystem services essential for human well-being will require an effective legal framework to prevent over-exploitation and give incentives for the protection of the fragile savanna woodland vegetation. An appropriate savanna woodland management policy will be required to guide changes in land use that accommodate the requirements of land users, aided by targeted conservation efforts to all woody plants and particularly for the highly utilized species for charcoal production as well as the multipurpose species. In addition, there is urgent need to build local capacity for improved harvesting and utilization of these tree species. This can be achieved through equipping local users with up to date information as well as observing the existing skills.

Carbon nanotubes (CNTs) have gathered a lot of interest because of their extraordinary mechanical, electrical and thermal properties and have potential applications in a wide variety of areas such as material-reinforcement and nano-electronics. The properties of nanotubes are dependent on their diameter and methods for determining this using atomic force microscopy (AFM) in tapping mode assume that the measured height of the tubes represent the real diameter. Based on early, faulty calculations, the forces in tapping mode were assumed to be much lower than in contact mode, however it was later shown that forces in tapping mode can at point of impact rival the forces present in contact mode. This means that there is a potential risk of tube deformation during tapping mode measurements, resulting in incorrectly determined diameters. This work studies CNTs deposited on a silicon-substrate to analyze the effect of three common AFM settings (tapping frequency, free oscillation amplitude and setpoint) to determine their effect on measured CNT diameters and recommendations for choosing settings are given. / Kolnanorör har skapat mycket intresse på grund av sina extraordinära mekaniska, elektriska och termiska egenskaper och har lovande tillämpningar inom en mängd olika områden så som materialförstärkning och nanoelektronik. Kolnanorörens egenskaper påverkas kraftigt av deras diameter och de metoder som använder sig av atomkraftsmikroskopi(AFM) för att mäta diametern hos rören antar att den höjd-data man får fram är ett bra mått på den verkliga diametern hos rören. Baserat på tidiga, felaktiga beräkningar, antog man att kraften i ’tapping mode’ skulle vara mycket lägre än i ’contact mode’ vilket skulle leda till att man inte deformerar ytan man undersöker. Senare forskning visade att kraften mellan spets och prov kan vara lika stor eller rentutav större i tapping mode än i contact mode under det ögonblick då spetsen slår ner i provytan. Det medför att det finns en potentiell risk för att man deformerar kolnanorören när man mäter på dom vilket skulle resultera i att man får felaktiga värden på deras diametrar. Under det här projektet har kolnanorör som placerats på ett kisel-substrat undersökts för att analysera hur tre vanliga inställningar hos AFMet påverkar de erhållna värdena för diametern hos kolnanorören. De tre inställningarna som testats är svängnings-frekvensen, svängnings-amplituden i luft och börvärdet hos svängnings-amplituden.