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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Nano TiO2-engineered anti-corrosion concrete for sewage system

Li, Zhen, Ding, Siqi, Kong, Lijuan, Wang, Xinyue, Ashour, Ashraf, Han, Baoguo, Ou, Jinping 12 January 2022 (has links)
Yes / In this study, anti-corrosion concrete for sewage system was developed with nano TiO2 (NT) and reactive powder concrete (RPC). The corrosion resistances of NT modified RPC (NTMRPC) in high concentration enhanced sewage were investigated from the perspectives of biological, physical and chemical corrosion resistances, respectively. In addition, mechanical properties of NTMRPC after sewage corrosion were also studied. Research results indicated that NT can endow RPC with antimicrobial property through their microorganism biodegradation properties. The inhibition and elimination rates of NTMRPC to its surface microorganisms were 37.35% and 80.93%, respectively. After sewage corrosion, the surface roughness, mass loss and deterioration depth of RPC were decreased by 62.57%, 15.48% and 18.44% due to the NT inclusion, respectively. In addition, the pH values of RPC in the deterioration depth ranges of 0-3 mm and 3-6 mm were increased by 11.45% and 23.62%, respectively. NT can restrain the strength deterioration of RPC in high concentration enhanced sewage. This may be due to the improved sewage biological anti-corrosion performances of RPC by inhibiting/eliminating the microorganisms on the surface of RPC as well as the enhanced sewage physical/chemical anti-corrosion performances of RPC by improving the compactness of RPC. / The authors thank the funding provided by the National Science Foundation of China 513 (51978127 and 51908103), and National Key Research and Development Program of China 514 (2018YFC070560 and 2017YFC0703410).
2

Ação de estimulantes vegetais na produtividade de alguns cultivos tropicais / Plant stimulants performance on some tropical crops yield

Paffaro, Luís Fernando 11 April 2017 (has links)
Cereais como a cevada e o arroz e leguminosas como o feijão, são importantes fontes de alimento no mundo. Alcançar maiores índices de produtividade não é apenas um fator econômico, mas social. Os reguladores vegetais têm o papel de estimular os diversos processos do desenvolvimento vegetal. Defensivos agrícolas passaram a serem estudados também como estimulantes vegetais, ao ser verificado que certas substâncias promoviam efeitos positivos na produtividade de cultivos. A fim de estudar esses efeitos em parâmetros de produtividade, quanto ao uso de substância específica e se ocorre diferença quando se modifica a fonte de reguladores vegetais numa formulação, foi realizada pulverização foliar com doses fixas dos produtos: (GA+NAA+BA), (GA+IBA+CN), nano TiO2 (nano dióxido de titânio) e tiametoxam em plantas de feijoeiro, cevada, arroz e em tomateiro cultivar Micro-Tom. Além disso, foi instalado um experimento com feijão via tratamento de sementes, com doses fixas dos produtos já citados, em rizotron e em vasos para avaliar o crescimento radicular. Os experimentos foram conduzidos em casa de vegetação no Departamento de Ciências Biológicas da ESALQ/USP. Os resultados obtidos foram submetidos à análise de variância e ao teste de Duncan através do software estatístico SAS. Em feijoeiro (aplicação via foliar) e tomateiro não foram encontrados efeitos significativos dos produtos na produtividade das plantas, contudo, alguns parâmetros foram influenciados por determinados tratamentos. Foi observada possível fitotoxidez no cultivo de tomate com o uso de tiametoxam ao se avaliar sua produtividade em relação ao controle. Em cevada, a aplicação de nano TiO2 aumentou a altura das plantas, o índice SPAD e o índice de colheita. Em arroz o tratamento GA+NAA+BA aumentou a altura das plantas e o tratamento tiametoxam promoveu maior número de perfilhos. Na análise do tratamento de sementes em vasos os resultados não foram significativos. Entretanto, o uso de nano TiO2 influenciou na área radicular. Em rizotron foi observado o maior CRV (crescimento radicular vertical) no tratamento com GA+NAA+BA. Ao final dos experimentos pode-se constatar também que o tratamento com GA+NAA+BA teve desempenho semelhante ao tratamento GA+IBA+CN. / Cereals like barley, rice and legumes like beans are important sources of food in the world. To achieve higher rates of productivity is not just an economic but a social factor. Plant regulators have the role of stimulating the various processes of plant development. Agricultural defensives were also studied as plant stimulants, as it was verified that certain substances promoted positive effects on crop productivity. In order to study these effects in productivity parameters, regarding the use of specific substance and if difference occurs when the source of plant regulators in a formulation is modified, a fixed dose of foliar spray was carried out: (GA+NAA+BA), (GA+IBA+CK), nano TiO2 (nano titanium dioxide) and thiamethoxam in common bean, barley, rice and tomato (Micro-Tom cultivar) plants. In addition, a bean experiment was installed through seed treatment with fixed doses of the mentioned products, in rhizotron and in pots to evaluate root growth. The experiments were conducted in a greenhouse at the Biological Sciences Department of ESALQ/USP. The results were submitted to analysis of variance and the Duncan test through SAS statistical software. In bean (foliar application) and tomato, no significant effects of the products were found on plant productivity; however, some parameters were influenced by certain treatments. Possible phytotoxicity was observed in tomato leaves with the use of thiamethoxam when evaluating its productivity in relation to the control. In barley the application of nano TiO2 increased the plant height, SPAD chlorophyll and the harvest indexes. In rice, the treatment GA+NAA+BA increased the plant height and the treatment with thiamethoxam increased the number of tillers. In the seed treatment in pots, analyses of the results were not significant. However, the use of nano TiO2 influenced the root area. In rhizotron, the highest CRV (vertical root growth) was observed in the GA+NAA+BA treatment. At the end of the experiments, it could be seen that the GA+NAA+BA treatment performed similarly to GA+IBA+CK treatment.
3

Ação de estimulantes vegetais na produtividade de alguns cultivos tropicais / Plant stimulants performance on some tropical crops yield

Luís Fernando Paffaro 11 April 2017 (has links)
Cereais como a cevada e o arroz e leguminosas como o feijão, são importantes fontes de alimento no mundo. Alcançar maiores índices de produtividade não é apenas um fator econômico, mas social. Os reguladores vegetais têm o papel de estimular os diversos processos do desenvolvimento vegetal. Defensivos agrícolas passaram a serem estudados também como estimulantes vegetais, ao ser verificado que certas substâncias promoviam efeitos positivos na produtividade de cultivos. A fim de estudar esses efeitos em parâmetros de produtividade, quanto ao uso de substância específica e se ocorre diferença quando se modifica a fonte de reguladores vegetais numa formulação, foi realizada pulverização foliar com doses fixas dos produtos: (GA+NAA+BA), (GA+IBA+CN), nano TiO2 (nano dióxido de titânio) e tiametoxam em plantas de feijoeiro, cevada, arroz e em tomateiro cultivar Micro-Tom. Além disso, foi instalado um experimento com feijão via tratamento de sementes, com doses fixas dos produtos já citados, em rizotron e em vasos para avaliar o crescimento radicular. Os experimentos foram conduzidos em casa de vegetação no Departamento de Ciências Biológicas da ESALQ/USP. Os resultados obtidos foram submetidos à análise de variância e ao teste de Duncan através do software estatístico SAS. Em feijoeiro (aplicação via foliar) e tomateiro não foram encontrados efeitos significativos dos produtos na produtividade das plantas, contudo, alguns parâmetros foram influenciados por determinados tratamentos. Foi observada possível fitotoxidez no cultivo de tomate com o uso de tiametoxam ao se avaliar sua produtividade em relação ao controle. Em cevada, a aplicação de nano TiO2 aumentou a altura das plantas, o índice SPAD e o índice de colheita. Em arroz o tratamento GA+NAA+BA aumentou a altura das plantas e o tratamento tiametoxam promoveu maior número de perfilhos. Na análise do tratamento de sementes em vasos os resultados não foram significativos. Entretanto, o uso de nano TiO2 influenciou na área radicular. Em rizotron foi observado o maior CRV (crescimento radicular vertical) no tratamento com GA+NAA+BA. Ao final dos experimentos pode-se constatar também que o tratamento com GA+NAA+BA teve desempenho semelhante ao tratamento GA+IBA+CN. / Cereals like barley, rice and legumes like beans are important sources of food in the world. To achieve higher rates of productivity is not just an economic but a social factor. Plant regulators have the role of stimulating the various processes of plant development. Agricultural defensives were also studied as plant stimulants, as it was verified that certain substances promoted positive effects on crop productivity. In order to study these effects in productivity parameters, regarding the use of specific substance and if difference occurs when the source of plant regulators in a formulation is modified, a fixed dose of foliar spray was carried out: (GA+NAA+BA), (GA+IBA+CK), nano TiO2 (nano titanium dioxide) and thiamethoxam in common bean, barley, rice and tomato (Micro-Tom cultivar) plants. In addition, a bean experiment was installed through seed treatment with fixed doses of the mentioned products, in rhizotron and in pots to evaluate root growth. The experiments were conducted in a greenhouse at the Biological Sciences Department of ESALQ/USP. The results were submitted to analysis of variance and the Duncan test through SAS statistical software. In bean (foliar application) and tomato, no significant effects of the products were found on plant productivity; however, some parameters were influenced by certain treatments. Possible phytotoxicity was observed in tomato leaves with the use of thiamethoxam when evaluating its productivity in relation to the control. In barley the application of nano TiO2 increased the plant height, SPAD chlorophyll and the harvest indexes. In rice, the treatment GA+NAA+BA increased the plant height and the treatment with thiamethoxam increased the number of tillers. In the seed treatment in pots, analyses of the results were not significant. However, the use of nano TiO2 influenced the root area. In rhizotron, the highest CRV (vertical root growth) was observed in the GA+NAA+BA treatment. At the end of the experiments, it could be seen that the GA+NAA+BA treatment performed similarly to GA+IBA+CK treatment.
4

Analýza vlivu obráběného materiálu na opotřebení a trvanlivost nástroje / Analysis of material to be machined influence on the wear and tool durability

Tolkner, Josef January 2012 (has links)
Machining technology is a multi disciplinary field, and together with the economy are playing always more important role in the success of the enterprise market products and services. Recent studies show that it requires very close link between technology, management and information technology such as the integration process and production planning, simulation of manufacturing systems, production flexibility, virtual machines, control algorithms, etc. The key changes are based on the requirements for miniaturization of products, higher production accuracy, closer tolerances, better surface quality, part of weight reduction, reduction of lot size and reducing production costs. The report is focused on machining titanium alloys. In the theoretical part are presented the properties and the distribution of titanium alloys. In the practical part is then carried out an experiment aimed to influence the composition of workpiece material on tool wear. Experiment results and recommendations are listed at the end of this report.
5

EXPLOSIBILITY OF MICRON- AND NANO-SIZE TITANIUM POWDERS

Boilard, Simon 15 February 2013 (has links)
The current research is aimed at investigating the explosion behaviour of hazardous materials in relation to particle size. The materials of study are titanium powders having size distributions in both the micron- and nano-size ranges with nominal size distributions: -100 mesh, -325 mesh, ?20 ?m, 150 nm, 60-80 nm, and 40-60 nm. The explosibility parameters investigated explosion severity and explosion likelihood for both size ranges of titanium. Tests include, maximum explosion pressure (Pmax), maximum rate of pressure rise ((dP/dt)max), minimum explosible concentration (MEC), minimum ignition energy (MIE), minimum ignition temperature (MIT) and dust inerting using nano-titanium dioxide. ASTM protocols were followed using standard dust explosibility test equipment (Siwek 20-L explosion chamber, MIKE 3 apparatus, and BAM oven). The explosion behaviour of the micron-size titanium has been characterized to provide a baseline study for the nano-size testing, however, nano-titanium dust explosion research presented major experimental challenges using the 20-L explosion chamber.

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