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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.
501

Studium procesu zrání a uchovávání ovoce / Study of fruit ripening and storage

Langová, Jiřina January 2009 (has links)
There are many changes in fruit quality during its ripening and storage. The following four apple varieties were studied: Champion, Glostr, Golden Delicious and Idaret. Amount of reducing sugars, total amount of sugars, quantities of acids, refractive solids and loss of starch were monitored. The changes of parameters, the differences between the varieties and differences in storage were compared. Parameters were monitored from mid-August 2008, when the apples ripened. After the harvest, apples were stored in a cool box at 2 - 3 ° C and at room temperature 20 - 23 ° C. Apples stored in the cool box were analyzed till the end of March 2009, and apples stored at room temperature until the beginning of January 2009. Total quantity of sugars in all varieties increases before harvest, while it decreases after picking the apples. The quantity of reducing sugars in apples rises gradually and after their picking it falls significantly in apples stored at 20 - 23 ° C. In apples stored in the cool box it continues rising until the end of November, and then it also decreases. Losses of starch are considerable and they are accelerated after the harvest. The quantity of acids also decreases throughout and amounts of refractive solids increases. For all varieties there are significant changes in storage at 20 - 23 ° C. Temperature, therefore, significantly affects processing of sugars and acids in fruit respiration.
502

Realizace edukační úlohy na experimentální stanici pro modelování torzních kmitů / Realization of educational problem based on torsional vibration apparatus

Bartošek, Daniel January 2011 (has links)
The presented master´s thesis deals with realization educational tasks on torsional vibration apparatus. It was designed and tested six educational experiments, to extend student´s knowledge of the static and dynamic properties of rotary systems. On the experimental apparatus it is possible to use inertial discs, adjustable semi-rotary damper with forced vibration crank drive unit. New set of shafts extends the variability of experimental apparatus. Students can realize the measurement of dynamic characteristics and torsional vibration using oscilloscope. New frame for the apparatus which meet all operation requirements was also designed. The solved problematics and all educational tasks are described in new prepared materials for teaching.
503

Stanovení makroprvků, organických kyselin a dalších parametrů v kečupech / Determination of macroelements, organic acids and other parameters in ketchups

Popelová, Nikola January 2017 (has links)
The aim of this master’s thesis is perform basic analyses of samples ketchups. The theoretical part describes the basic characteristics of tomato, tomatoes processing and production of puree and ketchup. Then there are described analytical methods which were used for analysing the selected parameters in ketchups. The experimental part deals with the determination of pH, total solids, organic acids, saccharides, macroelements and lycopene in ketchups. Citrate and acetate were analysed by IC. The amount of acetate in ketchups was about 5 times greater than the amount of citrate. Glucose, fructose and sucrose were analysed by HPLC. Glucose and fructose were determined in all samples but sucrose not. The ICP-OES method was used to determine four elements. Magnesium was the least represented element and sodium was the most represented element in the analysis. The amount of sodium was recalculated on the amount of salt. Lycopene was analysed by UV-VIS spectrometry. Its amount in ketchups is influenced by the variety of used tomatoes and plenty of other factors.
504

Investigation of acoustic waves generated in an elastic solid by a pulsed ion beam and their application in a FIB based scanning ion acoustic microscope

Akhmadaliev, Chavkat January 2004 (has links)
The rapid growth of the microelectronics industry in the last decades made it possible to produce structures in the sub-micrometer scale on silicon chips and to reach an integration scale under 100 nm. Decreasing the size and increasing the complexity of these structures make a control of quality and defects investigation more difficult. During a long time ultrasound devices are being used for nondestructive investigation of materials, like ultrasound microscopes, scanning photo-acoustic microscopes or scanning electron-acoustic microscopes, where acoustic waves are generated by acoustic transducers, focused laser or electron beams, respectively. The aim of this work is to investigate more precisely the acoustic wave generation by pulsed and periodically modulated ion beams in different solid materials depending on the beam parameters and to demonstrate the possibility to apply an intensity modulated focused ion beam (FIB) for acoustic emission and for nondestructive investigation of the internal structure of materials on a microscopic scale. The combination of a FIB and an ultrasound microscope in one device can provide the opportunity of nondestructive investigation, production and modification of micro- and nanostructures simultaneously. The FIB spot size in modern systems is comparable with that of a focused electron beam and the penetration depth of ions with energy of 20-60 keV is lower than 100 nm. This makes it possible to reach a sub-micrometer resolution of a scanning ion acoustic microscope. On the other hand side a FIB with energy of 20-60 keV is a good tool which can be used for the fabrication of nanostructures using ion milling, implantation or ion beam assisted deposition techniques. The bulk ultrasound emission in a solid was investigated using a pulsed high energy ion beam focused on aluminum, copper, iron and silicon samples. Oxygen, silicon and gold ion beams were applied in charge states from 1+ to 4+ with the pulse duration of 0.5 - 4 µs and an energy of 1.5 - 10 MeV. Intensity of the detected acoustic waves shows a linear dependence on the energy of the incident ions, on the ion flux as well as on the pulse duration. No influence of the ion charge and ion mass to the emission of acoustic waves was observed. The ion acoustic effect was applied for a nondestructive material inspection using intensity modulated FIB providing by the IMSA-100 FIB system with an accelerating potential of 30-35 kV. The achieved lateral resolution of this scanning ion acoustic microscope is in the micrometer range depending on the sample material and the beam modulation frequency. The resolution can be improved by increasing the frequency. The maximal modulation frequency which was obtained at IMSA-100 is about 2 MHz corresponding to lateral resolution of 4-5 µm on silicon. Using this microscope, some images of integrated microstructures on a silicon chip were obtained using the lock-in technique for filtering of the signal from the noise and increasing of the total imaging time. The possibility to visualize near sub-surface structure was demonstrated. Due to the strong sputtering effect and the long time of irradiation the imaged structures were significantly damaged. Si2+, Ge2+, Ga+ and Au+ ions were used. All these ions are quite heavy and have high sputtering coefficients. Long-time imaging improves the quality of acoustic images, i. e. the signal-to-noise ratio is reduced with the square root from the pixel time, but leads to significant erosion of the imaged structure.
505

Matematická analýza modelů mechaniky kontinua s implicitně zadanými materiálovými vztahy a okrajovými podmínkami / Mathematical analysis of models arising in continuum mechanics with implicitly given rheology and boundary conditions

Maringová, Erika January 2019 (has links)
In the thesis, we study the Navier-Stokes-like and the Navier-Stokes-Fourier- like problems for the flows of homogeneous incompressible fluids. In the first part of the thesis, we introduce a new type of boundary condition for the shear stress tensor, which includes the time derivative of the velocity. Therefore, we are able to capture the dynamic response of the fluid on the boundary. As the second part of the thesis, we include the published journal article co-authored by J. Žabenský on the Navier-Stokes-Fourier-like problem formulated in the complete thermodynamic setting. In both parts, the constitutive relations are formulated implicitly with the use of maximal monotone graphs. The main result of the thesis is the existence analysis for the above mentioned problems.
506

Treatment of wash water from road tunnels.

Byman, Lina January 2012 (has links)
Tunnels have become increasingly important in the development of road networks to meet rising transportation demands. Washing of road tunnels must be performed regularly to ensure traffic safety. The washing procedure generates significant amount of polluted wash water. Before discharge to a receiving water body, treatment is necessary to avoid potential degradation of the water quality. In this study, 12 in situ sedimentation experiments were conducted to evaluate treatment efficiency of sedimentation, with and without the addition of chemical flocculent. The findings showed that untreated tunnel wash water was highly polluted with total suspended solids (804-9690 mg/l), PAHs (0.4–29 μg/l) and heavy metals. Most pollutants were associated with the particulate material. Significant correlations (r2 > 0.95) were found between suspended solids and metals. Efficient removal of pollutants was possible by sedimentation with addition of flocculent. Within 20 hours of sedimentation low concentrations were reached of suspended solids (<15mg/l), PAHs (<0.1 μg/l), Cd (<0.05 μg/l), Cr (< 8 μg/l), Hg (<0.02 μg/l), Pb (<0.5 μg/l) and Zn (< 60 μg/l). The results confirm the possibility to treat tunnel wash water with sedimentation and flocculation and to discharge treated wash water to a recipient, provided particular attention is given to very sensitive water bodies.
507

Review on increasing efficiency of biogas production from sewage sludge.

Wang, Kai January 2012 (has links)
Sewage sludge is widely used as an important source for biogas production through digestion. Developing the high performance processes has a significant goal in order to promote energy efficiency and reduce the cost sewage sludge treatment. The problem of sewage sludge disposal is becoming top one which almost cost 50 % of running fee for a municipal wastewater treatment plant. This paper basically introduces three methods to improve the conventional digestion. However, they enhance the conventional digestion from different aspects. For examples, Two-phase anaerobic digestion enables to exhibit the merit of thermophilic anaerobic digestion and avoid the weak points of conventional digestion regarding odor problem. In two-phase anaerobic digestion, the acid and methane producing stages are separated. Extended solids retention time is an approach to separate the hydraulic retention time and solids retention time in an anaerobic digester by using recycle thickening. This method could benefit further de-composing the organics and increase methane formation. Dewaterability is the final step of anaerobic digestion process. Enhancing this part of process is an efficient way to increase the solid content of sludge that would reduce the transportation costs. In a nutshell, no matter on saving cost or energy perspectives, these three methods all promote biogas production efficiency up to a better performance, but various requirement of energy and cost are demanded. The paper displays and compares the advantages and disadvantages among three methods. There is no certain answer to which method is the best one; however, they can be chose to enhance digestion in different condition.
508

Slow Lithium Self-Diffusion on the Nanoscale Studied by Macroscopic and Microscopic Methods

Rahn, Johanna, Ruprecht, Benjamin, Strauß, Florian, Hüger, Erwin, Witt, Elena, Chandran, C. Vinod, Heitjans, Paul, Schmidt, Harald 11 September 2018 (has links)
Here, we report on slow Li self-diffusion in lithium containing metal oxide compounds with special emphasis on the influence of structural disorder on diffusion.
509

Advancements in Magnetic Resonance in Porous Media

Bowers, Clifford R., Vasenkov, Sergey 23 January 2020 (has links)
This is a brief summary of the Fourteenth International Bologna Conference on Magnetic Resonance in Porous Media (MRPM14).
510

Estimating Suspended Solids and Phosphorus Loading in Urban Stormwater Systems Using High-Frequency, Continuous Data

Melcher, Anthony A. 01 May 2019 (has links)
The introduction of pavement, buildings, and other impervious surfaces to urban landscapes greatly influences the quantity and quality of urban stormwater runoff. In this study, we designed and implemented modern stormwater monitoring technologies to establish a “smart” stormwater sensor network within the Northwest Field Canal (NWFC), an urban water conveyance located in Logan, Utah, USA. This network was designed to collect flow and water quality data at high frequencies and simultaneously at multiple locations. The observatory’s innovative method of inter-site communication and changing sampling frequencies during storm events was able to capture short duration events at the upstream and downstream ends of the NWFC and at multiple outfalls in the canal simultaneously without human intervention. We then investigated statistical regression models between turbidity and TSS so as to predict TSS at high frequencies. Finally, the addition of the high-frequency discharge data in the calibration procedure for a stormwater simulation model developed using the Environmental Protection Agency’s Stormwater Management Model did little to improve model performance at the downstream end of the canal, but did provide important insight into the overall contribution of discharge from individual stormwater outfalls to the NWFC. The results of this study inform water professionals on how to build and operate automated monitoring systems and how to create high-frequency estimates of TSS and TP loads in urban water systems.

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