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1
Pagano, Roberto. « Operative parameters of Silicon Photomultipliers ». Thesis, Universita' degli Studi di Catania, 2011. http://hdl.handle.net/10761/359.
Texte intégralRésumé :
Silicon photomultipliers are nowadays considered a promising alternative to conventional vacuum tube photomultipliers. SiPM structure consists in a parallel array of equal single pixels, each one made of a silicon p-n junction avalanche photodetector with an integrated resistor. The SiPM is biased above the breakdown voltage, that is, each pixel is operated in Geiger mode, above the breakdown voltage (BV) of the p-n junction.
The physical mechanisms operating in the device need to be fully explored and modelled to fully understand the device operational limits and possibilities. In this work, I studied the dark current behaviour of the pixels forming the Si photomultiplier as a function of the applied overvoltage and operation temperature. The data are well modelled by assuming that dark current is caused by current pulses triggered by events of diffusion of single minority carriers (mostly electrons) injected from the boundaries of the active area depletion layer (dominating at temperatures above 0à à à à °C) and by thermal emission of carriers from Shockley-Read-Hall defects in the depletion layer (dominating at temperatures below 0à à à à °C). The current-voltage characteristics of arrays from 5à 5 pixels up to 64à 64 pixels (pre-commercial devices) were also studied and some fabrication issues solved. Finally, some preliminary results on the effect of irradiation on the devices are also reported. In particular, measurements were performed after irradiating the devices with different species: X-rays, light ions (Boron) and heavy ions (Brome and Gold).I fotomoltiplicatori al Silicio sono al giorno d'oggi considerati un'alternativa promettente ai fotomoltiplicatori tradizionali. I SiPM sono formati da un reticolo (quadrato nel caso studiato) di celle (pixel) connessi in parallelo attraverso opportune resistenze (dette di quenching). Il SiPM e' polarizzato al di sopra della tensione di rottura (a valanga) di modo che ogni cella lavori in modalita' Geiger. E' necessario studiare dettagliatamente il principio fisico alla base del funzionamento e crease un modello per capire limiti e possibilita' di implementazione. In questo lavoro, ho studiato il comportamento della corrente di buio (dark current) della singola cella e delle matrici in funzione della tensione sopra breakdown e della temperatura di operazione. I dati sono modellati assumendo che la corrente di buio e' data da eventi di diffusione di portatori minoritari (elettroni) iniettati dai bordi dell'area attiva (regione di svuotamento), dominante a temperature superiori a 0à °C, e dall'emissione termica dei portatori da difetti Shockley-Read-Hall presenti nella regione di svuotamento, che domina a temperature sotto i 0à °C. Sono state anche studiate le caratteristiche corrente tensione (I-V) delle matrici da 5à 5 fino a 64à 64 (dispositivi pre-commerciali) e risolti alcuni problemi connessi alla fabbricazione.. Infine, sono riportati anche alcuni risultati preliminari sull'effetto dell'irraggiamento. In particolare, le misure sono state effettuare dopo irraggiamenti con raggi X, ioni leggeri (Boro) e ioni pesanti (Bromo e Oro).
2
Rojas, Jose Angel. « Relationship between the sludge settling characteristics and the parameters of the activated sludge system ». ScholarWorks@UNO, 2004. http://louisdl.louislibraries.org/u?/NOD,171.
Texte intégralRésumé :
Thesis (M.S.)--University of New Orleans, 2004.Title from electronic submission form. "A thesis ... in partial fulfillment of the requirements for the degree of Master of Science in the Department of Environmental Engineering."--Thesis t.p. Vita. Includes bibliographical references.
3
Boughtflower, Robert J. « Operating parameters for capillary electrochromatography (CEC) ». Thesis, University of Edinburgh, 2000. http://hdl.handle.net/1842/12403.
Texte intégralRésumé :
Miniaturisation of chromatographic systems is becoming increasingly desirable. Future developments will demand the analysis of smaller samples, at faster rates, with increasingly complex separations required. These demands are already starting to exceed the capabilities of conventional HPLC systems. Systems will require more column efficiency, operation at higher flow rates and detection of the undiluted eluent in the most sensitive detectors available. CEC offers the opportunity to achieve these goals. The main obstacles to using CEC reliably are the relatively unstable nature of purely electrically driven flows in packed beds, the lack of good quality CEC columns and the lack of dedicated instruments to perform CEC analysis. Also, CEC shares some of the same problems with HPLC of miniaturising the separation system without incurring dispersion related losses. The work detailed in this thesis contributes considerable advancements in most of these areas. Novel methods to produce high quality columns are described. The work demonstrates effective methods for coupling CEC to MS that make allowance for control of dispersion. The thermal limits of operation are discussed and demonstrated. Pressure-assisted CEC, demonstrating the practicality of performing CEC based analysis that is as reliable as current HPLC systems is shown. Proper optimisation of these type of uses will ultimately deliver CEC in a reliable format which will encourage a whole new audience of users to reap the benefits available.
4
Yilgor, Pinar. « Bioprocess Operation Parameters For Benzaldehyde Lyase Production ». Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/3/12605242/index.pdf.
Texte intégralRésumé :
In this study, the effects of bioprocess operation parameters on benzaldehyde lyase production were systematically investigated. For this purpose, the research program was carried out in mainly four parts. In the first part of the study, Escherichia coli K12 (ATCC 10798), having the highest benzaldehyde lyase production capacity, was selected as the host microorganism. Next, using the selected microorganism, the production medium was designed in terms of its carbon and nitrogen sources. Among the investigated media, the highest cell concentration and benzaldehyde lyase activity were obtained as 1.8 kg m-3 and 745 U cm-3, respectively, in the medium containing 8.0 kg m-3 glucose, 5.0 kg m-3 (NH4)2HPO4 and the salt solution. Thereafter, by using the designed medium, the effects of bioreactor operation parameters, i.e., oxygen transfer and pH, were investigated in pilot scale bioreactor. Oxygen transfer effects on benzaldehyde lyase production were investigated at QO/VR=0.5 vvmN=250, 375, 500, 625, 750 min-1 and at QO/VR=0.7 vvm, N=750 min-1 conditions. The highest cell concentration and benzaldehyde lyase activity were obtained at 0.5 vvm, 500 min-1 condition as 2.3 kg m-3 and 860 U cm-3, respectively. Finally, the effect of pH was investigated for benzaldehyde lyase production process at Qo/VR=0.5 vvm, N=500 min-1 condition, at pHC=5.0, 6.4, 6.7, 7.0, 7.2 and 7.8 values. Among the investigated pH values, the highest cell concentration and enzyme activity were obtained at pHC=7.0 condition as 2.1 kg m-3
775 U cm-3. However, the values obtained at this condition, were lower than the values obtained at pHUC=7.2 uncontrolled pH operation. Hence, medium oxygen transfer condition and uncontrolled pH operation are found to be favorable for benzaldehyde lyase production.
5
Edwards, Garren Chad. « Investigation of operating parameters in a vertical stirred mill ». Master's thesis, University of Cape Town, 2016. http://hdl.handle.net/11427/20442.
Texte intégralRésumé :
Due to the depletion of coarser grained ores, more mineralogically complex ores are being treated. These complex ores usually have finer grained valuable minerals. Liberation of these finer grained valuable minerals lies in grinding finer. Grinding to these fine sizes is energy intensive and using standard ball mills are energy inefficient at these sizes (P80 < 75μm). Therefore, stirred mills are becoming increasingly prevalent in the mineral processing industry. In order to optimize these mills, the effects and mechanisms of the significant variables need to be understood. This project investigated operating parameters against performance in a laboratory scale vertical stirred mill (Deswik mill), in an ultrafine grinding (UFG) application of MG2 reef in the bushveld igneous complex. The operating variables that were investigated are stirrer speed, solids concentration, media size and media filling. The Kwade stress energy model was tested on the grinding results. The grinding performance was quantified in two ways, i.e. grinding efficiency and grinding rate. The grinding performance for this study was also investigated through a statistical analysis. The experiments was designed using a face centred central composite design (FCCD) and the results was statistically analysed using a design of experiments (DOE) software.
6
Nikiema, Sompassaté Josiane. « Attenuation of greenhouse gas emissions by means of methane biofiltration optimization of the operating parameters ». Thèse, Université de Sherbrooke, 2008. http://savoirs.usherbrooke.ca/handle/11143/1911.
Texte intégralRésumé :
The main goal of this work has been that of optimizing the operating conditions of a biofilter, intended for the control of methane, an important greenhouse gas widely emitted by older or smaller landfill installations.The specific objectives were: (1) to select a suitable packing material (of organic or inorganic type); (2) to optimize the concentrations of input nutrients, mainly consisting of nitrogen, phosphorus, potassium and copper, which are intended to be introduced via the nutrient solution; (3) to determine the optimized values of the most important design parameters, such as the methane inlet load (which depends on the air flow rate and the inlet methane concentration); and (4) to model the biofilter performance. Firstly, the comparison of the two packing materials, one of organic type, and the other of inorganic type, has revealed that the latter was the more appropriate material for the methane biofiltration. Then, through the use of the selected packing material, the influence of each individual nutrient on the efficiency of the process has been investigated.The results obtained have shown that both nitrogen and phosphorus concentrations have to be controlled, while potassium and copper were revealed as being nutrients of only minor importance. Secondly, the optimization of the inlet gas flow rate and of the inlet methane concentration (and consequently, of the methane inlet load also), has been performed. According to the results of the studies, these parameters require good control during methane biofiltration because a limitation in biofilter performance could otherwise be induced. In addition, it was noted that the increase in the inlet gas flow rate led generally to a greater decrease of the methane conversion than the one induced by the inlet methane concentration. Finally, a new method, based on the use of solid extracts sampled from the methane biofilter, has been applied to the determination of methane biofilter kinetic parameters. Following this study, a steady state model of the methane biofiltration, taking into consideration the important operational parameters, as identified previously, has been developed. One particular feature of this model is that it takes into consideration the influence of the biofilter average temperature.The prediction results, obtained with the use of the model, have been successfully compared with the experimental results.
7
Nekovář, Martin. « Výpočet a měření parametrů asynchronních motorů ». Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-219752.
Texte intégralRésumé :
The theme of this master´s thesis is calculation and measurement of the parameters of induction motor. The thesis is divided into several parts. The first and the second part describes the general construction and operating principle of asynchronous motors. The construction includes a description of each part of induction motor, which consists of stator and rotor. The thesis deals with three-phase symmetrical and asymmetric single-phase motors. Principle of operation with using the rotating magnetic field, which is circular at three-phase motors, single phase motors have field elliptical shape. The next part contains the motor replacement scheme. The fourth part contains the calculation of motor´s parameters through the formulas. In this part the procedures for obtaining parameters of the replacement scheme of induction motor are defined. The process of calculating the parameters of the motor replacement scheme of threephase asynchronous motor is created according to given documentation is the next part for the certain type. The next content of the thesis describe finite element method, simulation and measurement of asynchronous motors to get of parameters from no-load and short-circuit test. The comparison of the results from measurement, analytical calculation and from simulation is given in the last chapter.
8
Rojas, Hector E. « The effect of ball mill operating parameters on mineral liberation ». Thesis, Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/50084.
Texte intégralRésumé :
In previous studies, the analysis of ball mill operating parameters and their effects on breakage phenomena has been limited to homogeneous materials. Though these studies have proven to be an asset in predictions of product size distributions and mill scale-up, they have not addressed the primary role of grinding, i.e. liberation.
The present investigation analyzes the effect of ball mill operating parameters on the breakage rates of both liberated and composite material. The operating parameters studied include mill rotational speed, ball size, mill charge, and wet versus dry grinding. Breakage rates have been determined experimentally utilizing a SEM-IPS image analyzer. The mineral sample used was acquired from ASARCO's Young Mine which is located in Jefferson City Tennessee. It was a binary ore consisting of sphalerite and dolomite.
Batch grinding experiments were conducted to provide breakage rates for the various composition classes. Breakage rates were then normalized with respect to energy to see if the changes in breakage rates associated with mill operating parameters were due to changes in breakage kinetics, or simply a function of energy input.
The energy normalized data indicates that the free dolomite breakage rates tend to normalize with respect to energy in the case of varying interstitial fillings. Furthermore, changes in mill rotational speed tend to provide energy normalizable breakage rates for both free dolomite and sphalerite. In all other cases, analysis of the breakage rates and energy-specific breakage rates indicate that a change in breakage kinetics may be occurring.
In general, particles containing a high proportion of sphalerite are more apt to break under impact conditions. On the other hand, particles containing a large proportion of dolomite were found to prefer attrition breakage conditions.Master of Science
incomplete_metadata
9
Chan, Chee-Wan. « Effects of powered harrow operating parameters on soil physical properties ». Connect to resource, 1992. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1200585211.
Texte intégral
10
McCarty, Michael James. « Determining the Optimum Operating Parameters of a Unipolar PWM Inverter ». DigitalCommons@CalPoly, 2010. https://digitalcommons.calpoly.edu/theses/287.
Texte intégralRésumé :
This study presents a determination of the optimum operating parameters of a unipolar PWM inverter through theoretical and experimental analysis. The inverter is investigated in its simplest form without input DC-DC conversion or output filtering. The intent of this study is to understand the core of the inverter thoroughly before adding peripheral elements such as output filtering. Variations on the input voltage level and switching frequency were investigated to determine their impacts on the operation of the inverter and harmonics produced. Theoretical modeling and calculations confirmed by experimental measurements and analysis allow determination of the inverter operating conditions which allow highest converter efficiency with lowest distortion. Results suggest highest efficiency and lowest harmonic distortion is achieved at the lowest input voltage (just above the peak of the desired fundamental component) and lowest switching frequency independent of output power.
11
Kriesi, Ruedi. « Critical operation parameters of solar multi-stage evaporators with self regulation / ». Lausanne, 1985. http://library.epfl.ch/theses/?nr=461.
Texte intégral
12
Notton, David. « Theoretical and experimental determination of key operating parameters for composting systems ». Thesis, Cardiff University, 2005. http://orca.cf.ac.uk/54547/.
Texte intégralRésumé :
The combination of increasing quantities of Municipal Solid Waste (MSW) and increased legislation for the disposal of this type of waste have created a need to develop different disposal or treatment routes for waste. Approximately 60% of MSW by mass is biodegradable and many disposal routes for this waste allow energy recovery. However the waste hierarchy presented in the National Waste Strategy for Wales emphasises the importance of materials recovery over energy recovery. It has been shown that the only way to achieve these targets is through the recovery of catering waste, which requires an in-vessel composting facility. In order to gain an insight into the aeration requirements for in-vessel composting, calculations were performed to ascertain the required airflow for the supply of oxygen, the removal of excess moisture and the removal of excess heat. It was found that approximately 450kJ are released for each mole of oxygen utilised whilst 500kJ are released per mole of carbon dioxide evolved. It was found that the air requirement for removal of heat from the process was approximately 100 times greater than the air required to supply oxygen to the system. In order to determine the power of aeration equipment required for composting facilities a static pressure test rig was constructed. From the results gained a model relating the static pressure to the bulk density of compost was developed. Initially a windrow composting system processing green waste at the Carmarthenshire Environmental Resources Trust (CERT) composting facility was studied. A canopy system was developed to monitor the respiration rate of this system and allow comparison between different feedstocks and control strategies. For a green waste only windrow the highest recorded respiration rate was 38gC02kgVS"1day"1. The respiration rate was observed to reduce with temperature above 55 °C. In addition to the green waste windrows a temperature managed windrow and a windrow constructed from a mixture of green waste and chicken litter were also tested. The final series of trials involved the testing of the ability of a containerised composting system to meet the Animal By-Products Regulations. The vessel was fed various mixtures of green waste and factory waste. Airflow and insulation within the vessel were analysed and a composting rate of over 45gC02kgVS'1day1 was achieved. If this had been sustained then the vessel may have met the Animal By-Products Regulations.
13
Ebermann, Marko. « Influence of geometric form deviations on operating parameters in hydrodynamic bearings ». Technische Universität Chemnitz, 2018. https://monarch.qucosa.de/id/qucosa%3A21225.
Texte intégralRésumé :
Hydrodynamic plain bearings are important machine elements. They are used in many areas of mechanical engineering, such as turbomachines, crankshaft bearings and gears. The geometry of the lubrication gap elemen-tarily influences the function as shown in several examples of abrupt failures in turbochargers. Due to toleranc-ing, the manufacturing requirements are very high. However, the question remains how large these deviations can be. ISO 12129-2 gives recommendations on form deviations depending on the minimum of plain bear-ing clearance (hmin). Nevertheless, there is no direct reference on the size or the strain on bearing. In DIN 31652-3, the tolerance of the bearing clearance is divided into -1/3 and +2/3 of itself. However, this tolerance merely has an indirect correlation with the size of the bearing and strain on the bearing. If these tolerance recommenda-tions are applied, the function of the plain bearing will not be completely fulfilled. Nonetheless, tolerances pro-vided by standards are used in geometric specifications. If these tolerances are used for in-company manufacturing, this is unproblematic in most cases. But if technical drawings are sent to an external manufacturer, toler-ance limits may be exhausted and the function cannot be ensured.
Within the framework of the research project presented here, a tolerance evaluation matrix has been developed. For this, the existing standards were analyzed. In this case, the ignorance of size (diameter and width) and signif-icant operating properties (speed, load, temperature, etc.) are insufficient. The project examined and simulated various possible deviations. Selected form deviations were manufactured. The validation of the simulation results were carried out on 30mm.
14
Ang, Yang Adrian. « Prediction and analytics of operating parameters on thermoelectric generator energy generation ». Thesis, University of Newcastle upon Tyne, 2017. http://hdl.handle.net/10443/3872.
Texte intégralRésumé :
The efficient use of energy at all stages along the energy supply chain and the utilization of renewable energies are very important elements of a sustainable energy supply system, specially at the conversion from thermal to electrical energy. Converting the low-grade waste heat into electrical power would be useful and effective for several primary and secondary applications. One of the viable means to convert the low-grade waste heat into electrical energy is the use of thermoelectric power conversion. The performance of thermoelectric generators, subjected to thermal effects, can vary considerably depending on the operating conditions, therefore it is necessary to measure and have a better understanding of the characteristics and performance of the thermoelectric generator. It is important to understand the thermoelectric generator’s dynamic behavior and interaction with its operating environmental parameters. Based on this knowledge, it is then significant to develop an effective mathematical model that can provide the user with the most probable outcome of the output voltage. This will contribute to its reliability and calculation to increase the overall efficiency of the system. This thesis provides the transient solution to the three-dimensional heat transfer equation with internal heat generation. It goes on to describes the transfer and generation of heat across the thermoelectric generator with dynamic exchange of heat. This solution is then included in a model in which the thermal masses and the operating environmental parameters of the thermoelectric generator are factored in. The resulting model is created in MATLAB. The comparison with experimental results from a thermoelectric generator system confirms the accuracy of the artificial neural network model. This thesis also presents two practical applications, the prediction of the input parameters with a given output voltage, and sensitivity analysis designed for the model. This is to enable users to customize the thermoelectric generator for their requirements. This allows for better usage of resources eventually.
15
Acar, Joseph 1977. « Effect of engine operating parameters and fuel characteristics on diesel engine emissions ». Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/30319.
Texte intégralRésumé :
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.Includes bibliographical references (leaf 32).
To examine the effects of using synthetic Fischer-Tropsch (FT) diesel fuel in a modern compression ignition engine, experiments were conducted on a MY 2002 Cummins 5.9 L diesel engine outfitted with high pressure, common rail fuel injection, a variable geometry turbo charger, cooled EGR and a fully configurable engine management computer. Additionally, the effect of varied injection timing and EGR rates were studied to examine how the engine can be optimized for FT fuel. The test fuels included two standard diesel fuels, one with 400 PPM sulfur content and the other 15 PPM sulfur. The experimental fuels were Syntroleum Corporation's S-1 fuel, as well as blends of 25% S-1 with a balance of 15 or 400 PPM D2. Tests were conducted with three engine operating conditions: 1682 RPM, 474 kPa BMEP; 2011 RPM, 1000 kPa BMEP; 2011 RPM, 1400 kPa BMEP. It was found that FT fuel reduced NOx emissions 19% in low load tests, but alone had little effect in higher load tests. FT fuel reduced particulate matter (PM) emissions in almost all test case, on the order of 25 to 75%. Retarding injection timing and increasing EGR both reduce NOx emissions. In the case of standard fuels, these reduction come at the expense of increased PM. However, FT fuel reduced this effect and allows for more retarded timing and further increased EGR rates to control NO. Blended fuels, containing 25% FT, by volume, and a balance of 15 PPM or 400 PPM fuel, were found to provide most of the benefit of straight FT fuel. The FT/15 blend reduced PM 40% and the FT/400 blend reduced PM 60%.
by Joseph Acar.
S.M.
16
Feng, Ming-Fa. « Fault diagnosis and prediction in reciprocating air compressors by quantifying operating parameters ». Diss., Virginia Tech, 1992. http://hdl.handle.net/10919/39786.
Texte intégralRésumé :
This research introduces a new method of diagnosing the internal condition of a reciprocating air compressor. Using only measured load torques and shaft dynamics, pressures, temperatures, flow rates, leakages, and heat transfer conditions are quantified to within 5%.
The load torque acting on the rotor of the machine is shown to be a function of the dynamics (instantaneous position, velocity, and acceleration) of the driving shaft, the kinematic construction, and the internal condition of the machine. If the load torque, the kinematic construction of the machine, and the dynamics of the rotor are known, then the condition of the machine can be assessed.
A theoretical model is developed to describe the physical behavior of the slider-crank mechanism and the shaft system. Solution techniques, which are based on the machine construction, crankshaft dynamics, and load torque measurements, are presented to determine the machine parameters. A personal computer based system used to measure the quantities necessary to solve for the machine parameters and the quantities used to compare with calculations is also documented.
The solution algorithm for multi-stage compressors is verified by decoupling the load torque contributed by each cylinder. Pressure data for a four-stage two-cylinder high pressure air compressor (HPAC) is used. Also, the mathematical model is proven feasible by using measured angular velocity of the crankshaft and direct measurements of the load torque of a single stage, single cylinder air compressor to solve for the machine parameters.
With this unintrusive and nondestructive method of quantifying the operating parameters, the cylinder pressures, operating temperatures, heat transfer conditions, leakage, and power consumption of a reciprocating air compressor can be evaluated.Ph. D.
17
Das, Suma Rani. « Investigation of Design and Operating Parameters in Partially-Filled Rubber Mixing Simulations ». University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1479151141596147.
Texte intégral
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Vedantham, Kumar. « Effect of operating parameters on the growth rate of solution grown crystals ». Master's thesis, Mississippi State : Mississippi State University, 2004. http://library.msstate.edu/etd/show.asp?etd=etd-07122004-101317.
Texte intégral
19
Thorwesten, Lothar [Verfasser]. « Veränderung ausgewählter ganganalytischer Parameter in der Rehabilitation operativ versorgter Kreuzbandläsionen / Lothar Thorwesten ». Hamburg : Diplom.de, 2000. http://d-nb.info/1184883246/34.
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BORGSTROM, MARK CRAIG. « ESTIMATION OF RECEIVER OPERATING CHARACTERISTIC (ROC) CURVE PARAMETERS : SMALL SAMPLE PROPERTIES OF ESTIMATORS ». Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184127.
Texte intégralRésumé :
When studying detection systems, parameters associated with the Receiver Operating Characteristic (ROC) curve are often estimated to assess system performance. In some applied settings it is often not possible to test the detection system with large numbers of stimuli. The resulting small sample statistics many have undesirable properties. The characteristics of these small sample ROC estimators were examined in a Monte Carlo simulation. Three popular ROC parameters were chosen for study. One of the parameters was a single parameter index of system performance, Area under the ROC curve. The other parameters, ROC intercept and slope, were considered as a pair. ROC intercept and slope were varied along with sample size and points on the certainty rating scale to form a four way factorial design. Several types of estimators were examined. For the parameter, Area under the curve, Maximum Likelihood (ML), three types of Least Squares (LS), and Distribution Free (DF) estimators were considered. Except for the DF estimator, the same estimators were considered for the parameters, intercept and slope. These estimators were compared with respect to three characteristics: bias, efficiency, and consistency. For Area under the curve, the ML estimator was the least biased. The DF estimator was the most efficient, and all the estimators except the DF estimator appeared to be consistent. For intercept and slope the LS estimator that minimized vertical error of the points from the ROC curve (line) was the least biased for both estimators. This LS estimator was also the most efficient. This estimator along with the ML estimator also appeared to be the most consistent. The other two estimators had no significant trend toward consistency. These results along with other findings, illustrate that different estimators may be "best" for different sample sizes and for different parameters. Therefore, researchers should carefully consider the characteristics of ROC estimators before using them as indices of system performance.
21
Oral, Edibe Eda. « Effect Of Operating Parameters On Performance Of Additive/ Zeolite/ Polymer Mixed Matrix Membranes ». Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12612957/index.pdf.
Texte intégralRésumé :
Membrane based separation techniques have been widely used and developed over
decades. Generally polymeric membranes are used in membrane based gas
separationhowever their gas separation performances are not sufficient enough for industrial feasibility. On the other hand inorganic membranes have good separation performance but they have processing difficulties. As a consequence mixed matrix membranes (MMMs) which comprise of inorganic particles dispersed in organic matrices are developed. Moreover, to enhance the interaction between polymer and zeolite particles ternary mixed matrix membranes are introduced by using low molecular weight additives as third component and promising results were obtained at 35 °
C. Better understanding on gas transport mechanism of these membranes could be achieved by studying the effect of preparation and operating parameters. This study investigates the effect of operation temperature and annealing time and temperature on gas separation performance of MMMs. The membranes used in this study consist of glassy polyethersulfone (PES) polymer, SAPO-34 particles and 2- v hidroxy 5-methyl aniline (HMA) as compatibilizer. The membranes fabricated in previous study were used and some membranes were used as synthesized while post annealing (at 120°
C, 0.2atm, N2 atm, 7-30 days) applied to some membranes before they are tested. The temperature dependent gas transport properties of the membranes were characterized by single gas permeation measurements of H2, CO2, and CH4 gases between 35 °
C-120 °
C. The membranes also characterized by scanning electron microscopy (SEM), thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). Annealing time and temperature affected the reproducibility and stability of the mixed matrix membranes and by applying post annealing step to mixed matrix membranes at higher temperatures and longer times, more stable membranes were obtained. For pure PES membranes thermally stable performances were obtained without any need of extra treatment. The permeabilities of all studied gases increased with increasing operation temperature. Also the selectivities of H2/CO2 were increased while CO2/CH4, H2/CH4 selectivities were decreased with temperature. The best separation performance belongs to PES/SAPO-34/HMA mixed matrix membrane at each temperature. When the temperature increased from 35 °
C to 120 °
C H2/CO2 selectivity for PES/SAPO- 34/HMA membrane was increased from 3.2 to 4.6 and H2 permeability increased from 8 Barrer to 26.50 Barrer. This results show that for H2/CO2 separation working at higher temperatures will be more advantageous. The activation energies were found in the order of
CH4 >
H2>
CO2 for all types of membranes. Activation energies were in the same order of magnitude for all membranes but the PES/SAPO-34 membrane activation energies were slightly lower than PES membrane. Furthermore, PES/SAPO-34/HMA membrane has activation energies higher than PES/SAPO-34 membrane and is very close to pure membrane which shows that HMA acts as a compatibilizer between two phases.
22
Giffin, Amanda. « Investigation of Operating Parameters Influencing Electrostatic Charge Generation in Gas-Solid Fluidized Beds ». Thesis, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/19728.
Texte intégralRésumé :
Electrostatic charge generation in gas-solid fluidized beds is a significant industrial problem. Associated problems include particle agglomeration and particle wall fouling. In the polymerization industry this may result in "sheets" of fused polymer, due to exothermic reaction causing the melting of the polymer, which can fall off and block the distributor plate disrupting fluidizing gas flow. Additionally, blockage of the catalyst feed or the polymer removal system can take place or the product can become non-uniform. All of these problems require shut-down of the reactor which results in lost production time. While this phenomena has been identified for many years, the mechanisms involved are not well understood, especially wall fouling and the distribution of charge within the bed. Isolation of individual parameters such as hydrodynamics, operating conditions, and material involved is necessary to evaluate how each parameter impacts charge generation during fluidization.
In this thesis, the fluidization system consisted of a stainless steel column, two online Faraday cups, and a retractable distributor plate. This system allowed for the simultaneous measurement of charge within different regions of the bed: the entrained fine particles, the particles adhered to the column wall, and the bulk of the bed. Additionally, mass and particle size distributions were measured and images of the layer of particles adhered to the column wall were taken for comparison. This allowed for a charge distribution comparison and evaluation of wall fouling.
Three different parameters were investigated: duration of fluidization, column wall material, and relative humidity of fluidizing gas. Fluidization time was studied for 15, 30, 60, 120, 180, and 360 min; relative humidity was investigated for 0%, 20%, 40%, 60%, and 80% relative humidity. Both fluidization time and relative humidity were evaluated at four different fluidization gas velocities, two each in the bubbling and slugging flow regimes. Column wall material was evaluated for a stainless steel and carbon steel column at two gas velocities, one each in the bubbling and slugging flow regimes.
Fluidization time was found to influence wall fouling in the bubbling flow regime as the particle layer continued to build as fluidization progressed. In the slugging flow regime, the particle layer developed within 15 minutes of the onset of fluidization. The bubbling flow regime was shown to have a greater capacity for charge generation than the slugging flow regime. This was due to the vigorous mixing in the bubbling flow regime resulting in more particle-particle interactions.
Column wall material was shown to influence wall fouling in the slugging flow regime due to the differences in surface roughness of the columns. This was due to the particle-wall contacts resulting in frictional charging which is the predominant charging mechanism in this flow regime. Charge was also impacted in the bubbling flow regime in those particles that were adhered to the column wall.
Relative humidity was found to influence wall fouling at the lowest gas velocity tested. However, variations in generation of charge occurred at all fluidization gas velocities tested; the charge-to-mass ratios for the particles adhered to the column wall in the slugging flow regime decreased with high relative humidities. This was due to either the formation of a water film layer on the column wall or instantaneous surface water films on the particles throughout fluidization.
23
Baqqar, Mabrouka. « Machine performance and condition monitoring using motor operating parameters through artificial intelligence techniques ». Thesis, University of Huddersfield, 2015. http://eprints.hud.ac.uk/id/eprint/28315/.
Texte intégralRésumé :
Condition monitoring (CM) of gearboxes is a necessary activity due to the crucial importance of gearboxes in power transmission in most industrial applications. There has long been pressure to improve measuring techniques and develop analytical tools for early fault detection in gearboxes. This thesis develops new gearbox monitoring methods by demonstrating that operating parameters (static data) obtained from machine control processes can be used, rather than parameters obtained from vibration and acoustic measurements. Such a development has important implications for the future of CM techniques because it could greatly simplify the measurement process. To monitor the gearbox under different operating and fault conditions based on the static data, three artificial intelligence (AI) techniques: a general regression neural network (GRNN), a back propagation neural network (BPNN), and an adaptive neuro-fuzzy inference system (ANFIS) have been used successfully to capture nonlinear variations of the electric motor current and control parameters such as load settings and temperatures. The three AI systems are taught the expected values of current; load and temperature for the gearbox in a given condition, and then measured values obtained from the gearbox with a known fault introduced are assessed by each of the AI models to indicate the presence of this abnormal condition. The experimental results show that each of GRNN, BPNN and ANFIS are adequate and are able to serve as an effective tool for gearbox condition monitoring and fault detection. The main contributions of this study is to examine the performance of a model based condition monitoring approach by using just operating parameters for fault detection in a two stage gearbox. A model for current prediction is developed using an ANFIS, GRNN and BPNN which captures the complicated inter-relations between measured variables, and uses direct comparison between the measured and predicted values for fault detection.
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Weichert, Miriam [Verfasser], et Christian [Akademischer Betreuer] Stremmel. « Praeoperative Parameter und perioperativer Verlauf - zur funktionellen Evaluation vor operativer Therapie des Lungenkarzinoms ». Freiburg : Universität, 2014. http://d-nb.info/1123479321/34.
Texte intégral
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Albusaidi, Waleed. « Techno-economic assessment of radial turbomachinery in process gas applications ». Thesis, Cranfield University, 2016. http://dspace.lib.cranfield.ac.uk/handle/1826/9872.
Texte intégralRésumé :
This research aims to assess the causes of inefficient and unstable operation of centrifugal compressors and turboexpanders in process gas applications in order to provide a solution for performance restoration and enhancement. It encompasses thermodynamic and flow evaluations to examine the efficiency and operating range improvement options of new units. Besides, this work is complemented by a technoeconomic analysis to provide a rounded outcome from these studies. In order to achieve the desired objectives, a novel integrated approach has been developed to assess the design and performance of multi-stage centrifugal compressors. The proposed systematic methodology involves five basic elements including evaluation of compressor selection, compressor sizing and casing structure, performance prediction at the design and off-design conditions, modelling of efficiency and head deterioration causes; and stage design evaluation. This will contribute towards evaluating the geometrical parameters of the new units’ designs at the early preliminary design phase, and thus, will be useful to identify the options for efficiency and operating range enhancements. For installed units, this approach can be implemented to assess the cause of inefficient and unstable operation by assessing the available operation data. A method was developed to predict the performance curve of multi-stage centrifugal compressor based on a stage stacking technique. This approach considers the advantages of Lüdtke and Casey-Robinson methods with an incorporation of a methodology for compressor selection and sizing to generate more accurate results. To emphasize the validity of the developed model, it has been evaluated for both low and high flow coefficient applications. The obtained results show a significant improvement in the estimated efficiency, pressure ratio, shaft power and operating range as compared with the existing methods. The centrifugal compressor is designed to run under various operating conditions and different gas compositions with the primary objective of high efficiency and reliability. Therefore, a new iterative method has been developed to predict the equivalent compressor performance at off-design conditions. This technique uses the performance parameters at design conditions as a reference point to derive the corresponding performance characteristics at numerous suction conditions with less dependency on the geometrical features. Through a case study on a gas transport centrifugal compressor, it was found that the developed approach can be applied for design evaluation on the expected variation of working conditions, and for the operation diagnosis of installed units as well. Furthermore, a parametric study has been conducted to investigate the effect of gas properties on the stage efficiency, surge margin, and compressor structure. The obtained results support the need for considering the gas properties variation when the off-design performance is derived. To evaluate the impact of internal blockage on the performance parameters, this study proposed an approach to model the effect of non-reactive deposits, which has been qualified using four operation cases and the obtained results are compared with the internal inspection findings from the stage overhauling process. This also covers the influential aspects of flow blockage on the technical and economic values. Since the main challenge here is to analyze the process gas composition in real time, the influences of the non-reactive deposits have been compared with the effect of the unanticipated gas composition change. Subsequently, it has turned out that the pressureratio parameter is not enough to assess the possibility of flow blockage and unexpected gas properties change. Moreover, it was observed that the stage discharge pressure was more sensitive to the fouled aftercooler comparing with suction and internal blockage. However, the effect of contaminated aftercooler on the surge point and discharge pressure and temperature of the upstream stage was found greater than its impact on the shaft power. Thus, a substantial surge margin reduction was detected when the first stage was operating with a fouled aftercooler comparing with the measured reduction as a result of unanticipated gas properties change. Furthermore, a larger pressure ratio drop was measured in the case of liquid carryover which revealed a more significant impact of the two phases densities difference comparing with the gas volume fraction (GVF) effect. The possibility of hydrate formation has been assessed using hydrate formation temperature (HFT) criteria. Additionally, this research highlights a number of challenges facing the selection of typical centrifugal stage design by assessing the contribution of design characteristics on the operating efficiency and stable flow range. Besides, an empirical-based-model was established to select the optimum impeller and diffuser configurations in order to make a compromise decision based on technical and economic perspective. It was concluded that there is no absolute answer to the question of optimum rotor and stator configuration. The preliminary aerothermodynamic evaluation exposed that the selection of the optimum impeller structure is governed by several variables: stage efficiency, pressure loss coefficient, manufacturing cost, required power cost, resonance frequency and stable operating range. Hence, an evaluation is required to compromise between these parameters to ensure better performance. Furthermore, it was argued throughout this study that the decision-making process of the typical stage geometrical features has to be based upon the long-term economic performance optimization. Thus, for higher long-term economic performance, it is not sufficient to select the characteristics of the impeller and diffuser geometry based on the low manufacturing cost or efficiency improvement criterion only. For turboexpanders, a simple and low cost tool has been developed to determine the optimum turboexpander characteristics by analysing the generated design alternatives. This approach was used in designing a turboexpander for hydrocarbon liquefaction process. Moreover, since the turboexpanders are expected to run continuously at severe gas conditions, the performance of the selected turboexpander was evaluated at different inlet flow rates and gas temperatures. It has turned out that designing a turboexpander with the maximum isentropic efficiency is not always possible due to the limitations of the aerodynamic parameters for each component. Therefore, it is necessary to assess the stage geometrical features prior the construction process to compromise between the high capital cost and the high energetic efficiency.
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Riggio, Silvio. « Méthanisation par voie sèche discontinue des fumiers : optimisation des paramètres opérationnels du procédé ». Thesis, Paris Est, 2017. http://www.theses.fr/2017PESC1183/document.
Texte intégralRésumé :
La Digestion Anaérobie (DA), ou méthanisation, est un procédé qui permet le traitement de déchets organiques et la production d’énergie renouvelable sous forme de biogaz. La DA par voie sèche permet en particulier la valorisation de substrats solides, offrant plusieurs possibilités aux traitements de résidus d’origine agricole tels les fumiers, des substrats constitués d’un mélange de paille, fèces et urine accumulés dans les litières des étables. Parmi les technologies disponibles en méthanisation, les « leach-bed reactors » (LBRs), constituent une option valide mais toutefois peu connue et peu développée soit au niveau scientifique qu’industriel.Dans le but d’optimiser ce procédé, plusieurs problématiques ont été affrontées : (i) la caractérisation bio-physico-chimique du fumier et du potentiel énergétique exprimé dans un LBR; (ii) l’optimisation de l’inoculation des réacteurs et de la température de digestion ; (iii) la co-digestion du fumier avec un substrat facilement biodégradable et la problématique reliées à la gestion des acides gras volatiles (AGVs) ainsi produits.Les résultats montrent que le fumier est un substrat lentement biodégradable qui nécessite un long temps de digestion. Cependant, il s’agit d’un déchet agricole adapté à la valorisation par méthanisation et dont les rendements de dégradation et de production de méthane en LBRs sont intéressants industriellement. Ce substrat est par conséquent une ressource organique précieuse dans le contexte agricole.Il a été montré que le fumier bovin contient une population méthanogène active capable de démarrer un procédé de digestion anaérobie efficacement sans l’ajout d’un inoculum externe spécifique, autant en mode mésophile que thermophile. Une analyse économique a démontré que cette propriété peut être exploitée afin de diminuer les coûts d’investissement initiaux d’un projet à l’échelle industrielle, en favorisant de cette manière le développement de la filière. De plus, les résultats montrent que pour la digestion du fumier en LBRs le mode thermophile ne comporte aucun intérêt par rapport à la production finale de méthane (qui est similaire pour les deux régimes) et que, au contraire, la valorisation par cogénération du méthane produit en thermophile diminue le rendement de production électrique surtout à cause d’une production de méthane très importante en début de digestion. Le régime mésophile parait donc être le mode de fonctionnement le plus adapté dans ce contexte.Enfin, le rôle joué par la percolation du lixiviat sur la mobilisation des AGV accumulés dans la fraction solide a été mis en lumière dans un réacteur de co-digestion traitant une fraction de lentement biodégradable (le fumier) et une fraction facilement biodégradable. Une stratégie a été développée afin d’étudier le problème de l’extraction et de la consommation des AGV dans le but d’améliorer le rendement global du procédé.Pour conclure, ce travail a permis d’optimiser certains paramètres fondamentaux dans la gestion d’un LBR. Cette technologie s’est révélée efficace dans le traitement du fumier, autant en mono-digestion qu’en co-digestion avec un substrat facilement biodégradable. Ces recherches montrent que l’utilisation des LBR est appropriée au contexte agricole et que la modification des paramètres de contrôle permet à ce procédé de répondre efficacement aux problématiques du terrain. Ce travail représente une avancée significative vers la compréhension et le développement des LBRs pour le traitement des résidus agricole et, plus globalement, des énergies renouvelables mobilisant des biomasses agricolesAnaerobic Digestion (AD) is a process which allows the treatment of organic waste and the production of renewable energy. In particular, dry AD allows the treatment of solid organic substrates, offering several possibilities to the enhancement of agricultural waste such as spent livestock bedding (a mixture of straw, faeces and urine). Among the available biotechnologies in AD, leach-bed reactor (LBRs) is a promising but yet poorly known process both at scientific and industrial level.In order to develop this process, several issues have been studied: (i) the bio-physico-chemical characterization of spent animal bedding and its digestion potential in LBRs; (ii) the optimization of the start-up and the operating temperature of the digesters; (iii) the co-digestion of spent animal bedding with an easily-degradable substrate and the issues connected to the management of the volatile fatty acids (VFAs) produced.The results showed that spent animal bedding is a slowly-degradable substrate which needs a long digestion time. However, it is a substrate suitable to be treated through AD displaying high degradation and methane production rates when processed in LBRs. This substrate is, therefore, a valuable organic resource in the agricultural context.Spent animal bedding was shown to contain an active methanogenic population able to start the process efficiently, both in thermophilic and mesophilic temperature, without requiring a specific external inoculation. An economic study at industrial scale proved that this peculiarity can be used to diminish the investment costs and then promote the development of this process. Moreover, thermophilic temperature was proved to be less advantageous over mesophilic condition. In fact, despite the very close methane yield reached in both temperature range, the different biogas production rates in thermophilic conditions would lead to a reduction of the final electric energy production in this condition. Mesophilic temperature was then shown to be the best operating condition for this process.Finally, the role played by the leachate recirculation in the mobilization of the VFAs accumulating in the solid bulk was highlighted in the case of a reactor co-digesting slowly- (spent livestock bedding) and easily-degradable substrates. A strategy was even proposed to efficiently face such a problem by optimizing both the VFA extraction and consumption with the objectives of increasing the overall process efficiency.In the end, this work allowed to optimize some important parameters for the correct management of the LBRs. This technology was proved to be efficient in the treatment of spent livestock bedding, both as a sole substrate or in co-digestion with an easily-degradable substrate. This research study demonstrates that LBRs is an adapted process for the agricultural context and this technology can easily answer to the full scale issues usually encountered. This work represents a significant advance towards the comprehension and development of LBRs to treat agricultural waste and, more generally, to the development of renewable energies based on biomass
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Moughrabiah, Wajeeh O. « Effect of operating parameters and particle properties on electrostatics in gas-solid fluidized beds ». Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/12867.
Texte intégralRésumé :
The influences of operating pressure, temperature and gas velocity on electrostatics in a fluidized bed of glass beads and different grades of polyethylene resin were investigated in a fluidization column of 150 mm inner diameter and 2.0 m height. Eight collision probes at different levels and radial positions measured the electrostatics in the bed. The electrostatics increased as pressure increased, probably due to an increase in bubble rise velocity, frequency and volume fraction. As the pressure increased, particle-particle and particle-wall collisions near the distributor and wall contributed heavily to charge generation. Temperature also played a role. At higher temperatures (up to 90°C), the polarity of net cumulative charge in the bed reversed. As the superficial gas velocity increased, the electrostatics increased. However, at higher gas velocities, the polarity in the freeboard was opposite to that in the bed, indicating that fines entrained from the column carried charges, resulting in a net charge of opposite polarity to that inside the bed.
For Geldart group B particles the degree of electrification in the bed slightly increased with decreasing particle size. Charging for group A particles was significantly greater than for group B particles. For binary mixtures of group A and B particles the electrostatics increased as the proportion of small particles increased.
As the relative humidity (RH) of fluidizing air increased, the electrostatics decreased. For the RH range (5-30%) explored, the sensitivity of the charging to RH varied significantly depending on the location of the probes.
As the proportion of fine glass beads (<30 µm) increased to 2.0 wt% in a fluidized bed of large glass beads (574 µm), the electrostatics in the bed decreased, likely because the fines acted as spacers between larger particles.
The electrostatics decreased as the proportion of an antistatic agent (Larostat) increased from 0.0 to 0.5 wt%, because Larostat tends to adsorb moisture and attach to the surface of the glass beads, consequently enhancing their surface conductivity. However, the degree of electrification increased when the wt% of Larostat exceeded 1.0%, likely due to the tendency of Larostat particles to adsorb water and to agglomerate.
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Gambrill, Richard. « The sensitivity of diesel engine performance to fuel injection parameters at various operating points ». Thesis, University of Nottingham, 2004. http://eprints.nottingham.ac.uk/11253/.
Texte intégralRésumé :
This thesis describes research undertaken to establish the advantages and disadvantages of using high pressure common rail fuel injection systems with multiple injection capabilities. The areas covered are detailed as follows. Oscillations in the rail pressure due to the opening of the injector can affect the quantity of fuel injected in subsequent injection events. The source of these oscillations has been investigated. A method of damping or reducing the oscillations has been defined and was applied. This successfully reduced the level of unpredictability of the quantity of injected fuel in subsequent injection events. A relationship between needle lift, injection pressure and the quantity of fuel injected was established. The effects of fuel injection parameters (main injection timing, split main separation and ratio) and engine operating parameters (boost pressure and EGR level) on emissions formations and fuel economy have been investigated at five operating points. Design of Experiments techniques were applied to investigate the effect of variables on pollutant emissions and fuel consumption. The sensitivity and linearity of responses to parameter changes have been analysed to assess the extent to which linear extrapolations will describe changes in smoke number (FSN) and oxides of nitrogen (NOx); and which parameters are the least constricting when it comes to adjustments of parameter settings on the FSN-NOx map. Comparing results for split main and single injection strategies at the five operating conditions shows that split main injection can be exploited to reduce NOx or FSN values at all conditions and both NOx and FSN simultaneously at high load conditions. The influence of changing engine speed and brake mean effective pressure (BMEP) on FSN and NOx emissions with given fixed values of parameter settings has been investigated. This established how much of the operating map could be covered by discrete calibration settings. Finally the variation in parameter settings required to maintain fixed FSN and NOx values across the operating map, near the optimum trade-off on the FSN-NOx map, was analysed. Combining the information gained from the individual investigations carried out highlighted some techniques that can be used to simplify the calibration task across the operating map, while also reducing the amount of experimental testing required.
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Su, Chaoran. « Influence of lead impurity and manganese addition on main operating parameters of zinc electrowinning ». Master's thesis, Université Laval, 2017. http://hdl.handle.net/20.500.11794/27769.
Texte intégralRésumé :
L'influence des ions Pb2+ sur le dépôt de zinc a été étudiée dans l'électrolyte acide de sulfate de zinc avec et sans Mn2+. La polarisation galvanostatique, la polarisation potentiodynamique, la voltammétrie cyclique (VC), les mesures de bruit électrochimique (MBE) et la spectroscopie d'impédance électrochimique (SIE) en conjonction avec la microscopie électronique à balayage (MEB) et la diffraction des rayons-X (XRD) ont été considérés. L'effet de différents paramètres de fonctionnement tels que la concentration de Zn2+, la concentration d’acide sulfurique, la densité de courant, l'agitation de l’électrolyte et la température a été étudié en présence de Mn2+ et Pb2+. Les résultats galvanostatiques utilisant un électrolyte standard de zinc contenant 12 g/L de Mn2+ (ES) ont montré que les ions de plomb ajoutés à l’ES conduisaient à une augmentation du potentiel cathodique et de l'efficacité de courant (EC) du dépôt de zinc. L'augmentation de la concentration de Mn2+ dans l'électrolyte a entraîné une diminution du potentiel cathodique et d’EC du dépôt de zinc à cause de l'effet de dépolarisation du MnO4- formé. En outre, l'augmentation de la densité de courant de 45 à 60 mA/cm2 et de l'agitation de 60 à 412 tr/min ont donné lieu à une augmentation du potentiel et à une diminution d’EC. L'augmentation de la température de 35 à 45°C a conduit à une diminution du potentiel cathodique. Pour l'électrolyse de longue durée (72 h), la teneur de Pb dans le dépôt de zinc en utilisant l'anode Pb-0,7%Ag était de 1,90-1,98 ppm, presque équivalente à celle employant l'anode de Pt avec l’addition de 0,15-0,2 mg/L de Pb2 +. L'électrolyse à 40°C et 52,5 mA/cm2 en présence de plomb jusqu'à 0,1-0,2 mg/L dans un électrolyte contenant 12 g/L Mn2+ pourrait être considérée comme des meilleurs paramètres opérationnels pour le procédé d'extraction électrolytique. Les études SIE ont montré que le dépôt de zinc sur le zinc est plus facile que celui du zinc sur l'aluminium. L’analyse des MBE a révélé que l'augmentation des concentrations de Pb2+ (0,05-0,8 mg/L) dans l'électrolyte de zinc sans Mn2+ s'accompagne d'une diminution de l'inclinaison et d'une augmentation des valeurs du kurtosis qui puissent être corrélées à la morphologie du dépôt de zinc.The influence of Pb2+ ions on zinc deposition was investigated in acidic zinc sulfate electrolyte with and without Mn2+ ions. Galvanostatic polarization, potentiodynamic polarization, cyclic voltammetry (CV), electrochemical noise measurements (ENM) and electrochemical impedance spectroscopy (EIS) in conjunction with scanning electron microscopy (SEM) and X-ray diffraction (XRD) have been considered. Effects of different operating parameters such as Zn2+ ions concentration, sulfuric acid concentration, current density, electrolyte agitation and temperature were investigated in presence of Mn2+ and Pb2+ ions. The galvanostatic results using standard zinc electrolyte containing 12 g/L Mn2+ (SE) showed that lead ions added to the SE led to an increase in the cathodic potential and current efficiency (CE) of zinc deposit. Increasing Mn2+ concentration in the electrolyte resulted in decrease of cathodic potential and CE of zinc deposit due to the depolarization effect of formed MnO4-. In addition, increases of current density from 45 to 60 mA/cm2 and agitation from 60 to 412 rpm resulted in an increase of overpotential and decrease of CE. Increase of temperature from 35 to 45°C led to a decrease of cathodic potential. For long time electrolysis (72 h), the Pb content in zinc deposit using Pb-0.7%Ag anode was 1.90-1.98 ppm, almost equivalent to that employing Pt anode with addition of 0.15-0.2 mg/L of Pb2+. Electrolysis at 40°C and 52.5 mA/cm2 in presence of lead up to 0.1-0.2 mg/L in an electrolyte containing 12 g/L of Mn2+ could be considered as best conducted operating parameters for electrowinning process. EIS studies showed that zinc deposition on zinc is easier than that of zinc on aluminum. ENM revealed that increase of Pb2+ concentration (0.05-0.8 mg/L) in zinc electrolyte without Mn2+ is accompanied with a decrease of skew and increase of kurtosis values that could be correlated to the morphology of zinc deposit.
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BARNALA, PUKHRAJ K. « Optimization of Operating Parameters of a Material Recovery Facility using Lean Six Sigma Techniques ». University of Toledo / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1321575835.
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Nathoo, Jeeten. « Optimisation of electrolyte composition and operating parameters for the electropolishing of 304 stainless steel ». Master's thesis, University of Cape Town, 2003. http://hdl.handle.net/11427/5430.
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Saptari, Adi. « PC computer based algorithm for the selection of material handling equipment for a distribution warehouse based on least annual cost and operating parameters ». Ohio : Ohio University, 1990. http://www.ohiolink.edu/etd/view.cgi?ohiou1183473503.
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Celik, Eda. « Bioprocess Design Parameters For Beta-lactamase Production By Bacillus Species ». Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/1121029/index.pdf.
Texte intégralRésumé :
In this study, the effects of bioprocess design parameters on β
-lactamase production were systematically investigated using wild type Bacillus species. For this purpose, the research programme was carried out in mainly four parts. Initially, potential &
#946
-lactamase producers were screened and Bacillus licheniformis ATCC 25972, a constitutive &
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-lactamase producer, was selected. Next, the effects of bioprocess medium components, i.e., carbon sources (glucose, fructose, sucrose, citric acid and glycerol), inorganic nitrogen sources ((NH4)2HPO4 and NH4Cl) and organic nitrogen sources (yeast extract, peptone and casamino acids), were investigated in agitation and heating rate controlled laboratory scale bioreactors. Thereafter, by using the designed medium, the effects of bioprocess operation parameters, i.e., pH and temperature, on &
#946
- lactamase activity were investigated in order to achieve a higher &
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-lactamase production. Among the investigated bioprocess conditions, the highest &
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- lactamase activity was obtained as 275 U cm-3, in the medium with 10.0 kg m-3 glucose, 1.2 kg m-3 (NH4)2HPO4, 8.0 kg m-3 yeast extract and the salt solution, at pH0=6.0, T=32°
C, N=200 min-1, which was 7.9 fold higher than the activity obtained in the reference medium. Finally, using the optimum bioprocess parameters obtained in laboratory scale experiments, the fermentation and oxygen transfer characteristics of the bioprocess were investigated in 3.0 dm3 pilot scale bioreactor, having temperature, pH, foam and stirring rate controls, at Q0/V=0.5 vvm and N=500 min-1 oxygen transfer conditions. The variations in &
#946
- lactamase activity, cell, glucose, amino acid and organic acid concentrations with the cultivation time
the oxygen uptake rate and the liquid phase mass transfer coefficient values were determined. Throughout the bioprocess, overall oxygen transfer coefficient (KLa) varied between 0.008-0.016 s-1
oxygen uptake rate varied between 0.001-0.003 mol m-3 s-1. Furthermore, rate limiting step analysis was performed
the yield and maintenance coefficients for the bioprocess as well as the kinetic parameters for &
#946
-lactamase were determined.
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Haykir, Isik. « Investigation Of Bioprocess Parameters For Glucose Isomerase Production By Bacillus Thermoantarcticus ». Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/2/12608536/index.pdf.
Texte intégralRésumé :
In this study, the effects of bioprocess parameters on glucose isomerase roduction by Bacillus thermoantarcticus (DSMZ 9572) were investigated. For his purpose, firstly, in laboratory scale shake-bioreactors, a defined medium
was designed in terms of its carbon and nitrogen sources, to achieve the highest glucose isomerase activity. Optimum concentrations of medium components were determined by a statistical approach, namely Response Surface Methodology (RSM). RSM defined the relationship between the response, glucose isomerase activity and the independent variables, medium components. The highest glucose isomerase volumetric activity was obtained as 1630 U L-1 in the optimized medium containing 10.64 kg m-3 xylan, 5.66 kg
m-3 yeast extract, 5.92 kg m-3 (NH4)2SO4, 0.25 kg m-3 MgSO4.7H2O, 0.001 kg m-3 FeSO4.7H2O, 0.001 kg m-3 ZnSO4.7H2O , 0.000075 kg m-3 MnSO4. H2O,
and 0.00001 kg m-3 CuSO4.5H2O at conditions: pH0= 6.0, T=55°C, N=200 min-1. Then by using the designed medium, pH and oxygen transfer conditions of the bioprocess were investigated in 3.0 dm3 pilot scale bioreactor. The effect of pH was analyzed at pH=6 uncontrolled and controlled operations with the following conditions: air inlet rate of Q0/VR=0.5 vvm and agitation rate of N=500 min-1. The effects of oxygen transfer parameters were examined, at pH=6 controlled condition, at an air inlet rate of Q0/VR=0.5 vvm and the agitation rates of N=300,500,750 min-1. The variations in glucose isomerase activity, cell, amino acid and organic acid concentrations with the cell cultivation time, specific cell growth rate, the oxygen uptake rate, the liquid phase coefficient by using the dynamic method, maintenance coefficient for oxygen and yield coefficients were determined. The highest glucose isomerase volumetric activity and cell concentration, 1838 U L-1 and 2.26 kg m-3 at the 24th of the cell cultivation were attained at 0.5 vvm, 500 min 1 and pH=6 uncontrolled operation.
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Bothner, Rose. « An optimization model for selecting the economical cutting parameters in an external forward turning operation / ». Online version of thesis, 1990. http://hdl.handle.net/1850/10592.
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Saini, Sunil. « Bioreactor for the production of tissue engineered cartilage : defining operating parameters for optimal construct growth ». Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/10226.
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Man, Kayiu. « Investigations of operating parameters on controlled auto-ignition combustion in a four stroke gasoline engine ». Thesis, Brunel University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.429235.
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Hung, Yung-Cheng, et 洪雍程. « A Study on the Operative Parameters in the Production of Compost Tea from Food Waste ». Thesis, 2006. http://ndltd.ncl.edu.tw/handle/34122400080361733978.
Texte intégralRésumé :
碩士國立高雄海洋科技大學
海洋環境工程研究所
94
The Taiwan Environmental Protection Administration (Taiwan EPA) has promoted the food waste recycling policy since 2001. However、it runs into many practical difficulties: (1) More than 75% of the food waste relies on pig feeding that is not accepted by the Council of Agriculture. (2) Due to the growing popularity of composting、problems such as odor emitting、large production area is required for the long maturing time. (3) Huge amount of the leachate produced during the composting processes are difficult to handle. (4) The market value of the compost made of food waste is not well established. To resolve the problems、this study utilizes food wastes、leachate and mature compost as raw materials to precede aerobic-like fermentation for making compost tea. During the course of fermentation、physical、chemical、and biological parameters were monitored and discussed to find out applicable operating parameters. Major findings of this research include: (1) pH and ORP decrease at the initial stage、and rise up again at the mature stage. They are the handiest operating parameters. (2) In the process of turning food wastes into compost tea、oil and grease were also degraded、and the final degradation can be more than 70% of removals. (3) The final C/N ratio is 16.25 for making compost tea from food waste、and 15.16 for that of leachate、and 10.85 for that of mature compost. (4) For up to 23 VOCs were identified with more than 80% of the total VOCs are alcohols and terpenes for making compost tea from food waste. While in the case of making compost tea from leachate、only 5 VOCs can be identified with alcohol as the major content. When using mature compost to make tea、18 VOCs were identified with alcohols and ethers as the major content. (5) Fecal Coliform monitoring results indicate that pathogenic bacteria can be inhibited during the course of making compost tea. It is suspected that low pH (as low as 3.25 on the 7th day) inhibited the growth of Fecal Coliform. (6) The germination test results indicate that the compost tea is helpfully in growth of plants. (7) The electrical conductivity value and the concentration of NH3-N were found harmful to the growth of plant; thus、the concentrated compost tea needs to be diluted before application. (8) The N、P、and K content of the finished products are complied with the fertilizer standard (5%). Finally、(9) the harmful content of As and Cd were also below the limiting value of fertilizers. As a conclusion、the parameters such as pH、ORP、EC、C/N ratio、degradation rate of oil、NH3-N、N、P、K、and Fecal Coliform can be chosen to serve as the operating parameters for stabilizing compost tea manufacturing quality. This study had also demonstrated the technical feasibility of making compost tea from food waste、leachate、and mature compost.
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Huang, Chun-Ming, et 黃鈞民. « Pre-operative concurrent chemoradiotherapy for patients with locally advanced or low rectal cancer-The impact of clinical parameters and pathologic characteristics on prognosis ». Thesis, 2012. http://ndltd.ncl.edu.tw/handle/98583915519428798168.
Texte intégralRésumé :
碩士高雄醫學大學
醫學研究所
100
The incidence of colorectal cancer (CRC) in Taiwan has been rapidly increasing in the past few years, and CRC is the second most common cancer and also the third leading cause of cancer death in Taiwan. For locally advanced rectal cancer (T3-4 or N1-2), preoperative chemoradiotherapy (CCRT) has been demonstrated to achieve a lower local recurrence rate and good sphincter preservation rate. Several prospective and retrospective analyses suggest that pathological stage of disease after preoperative CCRT has a significant prognostic impact on disease-free and overall survival. In particular, the subgroup of patients who achieve a complete pathological response has a very low risk of local or distant recurrence. Traditionally, it is usually depends on TNM stage to determine whether patient receives preoperative CCRT or not. This proposal is aimed to discover clinical factors that can increase the power to predict the efficacy of preoperative CCRT.
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Corti, Ferdinando, Bruno Zanoni et Lorenzo Guerrini. « Innovation in extra virgin olive oil (evoo) processing ». Doctoral thesis, 2023. https://hdl.handle.net/2158/1300080.
Texte intégralRésumé :
The thesis was motivated by the need to enrich the current knowledge in the extra virgin olive oil (EVOO) processing. In particular, the experimental studies focused on critical issue for the EVOO quality, related to three different fundamental operations: the olive fruit storage before milling, the temperature control during malaxation and the cross-batch contamination in the decanter centrifuge. The innovative features of the research work concerned both the plant and machines and the methodological approaches for the study of the relationship between the operative parameters/ procedures and EVOO quality.
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« Bioprocess Operation Parameters For Benzaldehyde Lyase Production ». Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/3/12605242/index.pdf.
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Lin, Yung-Ful, et 林永富. « Study of Processing and Optimal Operating Parameters ». Thesis, 2007. http://ndltd.ncl.edu.tw/handle/43077896625611932784.
Texte intégralRésumé :
碩士國立臺灣海洋大學
機械與機電工程學系
95
For the recent year，people have already known the importance of the resource and reuse of organic waste，especially the boosting and implement of reusing the kitchen waste。For the present，the government are boosting the policy of recycle the organic waste and compost。The study of the dissertation is about designing a small scale of kitchen waste equipment by Anaerobic Digestion and discussing the characteristics of the stuff by different parameter。By the coercive implement of the government，the recycling of organic waste has further development。The Kitchen waste compost and feedstuff will increase intensively。Therefore，promote the efficient of the producing procedure and reduce the fee is the key to boost and execute。According to the experiment，the average cost of the depletion electric power reaches at 14.86 NT dollars per kilogram and the average weight of the kitchen waste produces 158.38 kilogram per ton。The main technology of organic waste resource lies in selecting the apparatus and appropriate operation，and by good planning and designing，we can achieve the purpose of reducing and reusing the waste。 Keyword：oragnic wastes、compost、kitchen waste、thermophilic anaerobic digestion
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Fan, Chin-Yu, et 范今瑀. « Optimization of Operating Parameters for Stripper Recycle System ». Thesis, 2017. http://ndltd.ncl.edu.tw/handle/59699603733174246425.
Texte intégralRésumé :
碩士國立中興大學
化學工程學系所
105
The purpose of this research is to find out the major controllable factors for the Stripper Recycle System of an opto-electronic fab. According to the result of the full factorial experiments, the optimization of operating can be estimated. The experiments included parameter adjustment as well as the cost-effectiveness analysis. The results pointed out that flow rate of feed, steam pressure, rotation speed are the major controllable factors. Based on Thin Film Evaporator of SRS, the results of the eighteen groups of experiments revealed that the significance of influence is in the order of rotation speed＞steam pressure＞feed flow. As for the full factorial experiment, the optimal values of controllable factors are feed flow kept at 160 L/hr, steam pressure kept at 5 kg/cm2 and rotation speed kept at 50rpm. It has the cost-effectiveness of increasing stripper recycle rate by 1.55%, decreasing waste production rate by 19.46 ton/yr and saving the stripper purchase cost of NTD$1,322,600.
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Guan, Ru-Ying, et 管如英. « Compacted Wastewater Treatment Unit : Design and Operation Parameters ». Thesis, 2011. http://ndltd.ncl.edu.tw/handle/45788581970655550691.
Texte intégralRésumé :
碩士國立中興大學
環境工程學系所
99
Compacted wastewater treatment units are mainly used to treat the residence wastewater. The type and size of the compacted units depended on the building size and number of residence. The major design parameters for the compacted units must follow the published “Manual of Compacted Wastewater Treatment Units: Design Parameters”. The design documents then were reviewed by EPA. The approved design documents were used to construct the wastewater treatment unit for marketing. This study focused on the evaluation of an approved wastewater treatment unit of 2.5 CMD and 6.5 CMD. According to the results of evaluation, a new model of 100 CMD was designed. The new model of 100 CMD was then reviewed with the design parameters. The major evaluated parameters were: HRT of the clarifier (with two major functions: settling and SS storage), HRT of the contact aeration tank, air supply (with two major functions: decomposition of BOD and air-lift recycling of 2nd clarified SS), organic loading of the contact aeration tank, surface loading of the 2nd clarifier, solid loading of the 2nd clarifier, and HRT of the disinfection tank. After the evaluation of the new model of 100 CMD, the design parameters were in comparison with the approved units (2.5 CMD and 6.5 CMD). The results indicated that the new model of 100 CMD could be employed to treat the wastewater discharged from a 400 – residence building.
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Lin, Jia-He, et 林佳禾. « Optimization of Operating Parameters in the SAW/GC System ». Thesis, 2010. http://ndltd.ncl.edu.tw/handle/7g2he2.
Texte intégralRésumé :
碩士中原大學
電子工程研究所
98
Abstract Surface Acoustic Wave (SAW) Sensor has been quite widely used in gas detection sphere. Based on the surface wave transmission on the solid surface, the sensing stimulus can be determined through the SAW oscillator frequency drift to achieve the purpose of vapor sensing. The surface acoustic wave devices were studied in this paper for high sensitivity, low cost, and compact size in gas chromatography system. Quantitative study includes the optimization of the gas flow rate experiment, single gas under constant temperature experiments and mixed gas under constant temperature experiments. Finally, the scheme of modulated heating rate, with mixed gas heating procedure is used to study the gas chromatography/SAW system and optimal operating conditions. The results show that four gas mixture the heating rate and temperature has been successfully distinguished by varying, including ether, toluene, butyl alcohol and cyclohexanone. "Heating rate" and "temperature-programmed" are two effective factors to speed the gas separation time. This work is important for the future development of a high speed and compact gas chromatography/SAW system.
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Wang, Hun-You, et 王弘柚. « Optimum Operation Parameters for an HF Wastewater Treatment System ». Thesis, 2009. http://ndltd.ncl.edu.tw/handle/66000575631711373749.
Texte intégralRésumé :
碩士國立成功大學
工業與資訊管理學系專班
97
This study is intended to solve the problems of an hydrofluoric acid (HF) wastewater treatment system in the semiconductor industry. A wastewater treatment factory of semiconductor industry in Taiwan was used to research the operational condition of the system. As the quantity of chemicals was controlled by the pH meter and the fluorine ion meter, it was discovered that the control mode easily resulted in excess use of chemicals. As a result, the cost of the system increased easily. The goal of this study is to find out the optimum operation parameters for an HF wastewater treatment system. By using Taguchi Method, Taguchi’s orthogonal arrays, S/N ratio response forms, S/N ratio response plots, and analysis of variance (ANOVA), better operation parameters could be determined. Combining the Taguchi method and Response Surface Methodology (RSM), a better RSM model that described the equal effect could be matched. Thus, the optimum operation parameters with the least cost of chemicals could be obtained. By using the optimum operation parameters, it was proved that the parameters could determine the quality target. The cost of chemicals was significantly decreased by 13%. This could bring great benefit to the industry in the long run.
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Chang, Chien-Kuo, et 張建國. « Study of logistic parameters affecting operation and support costs ». Thesis, 2003. http://ndltd.ncl.edu.tw/handle/30996782224500119608.
Texte intégralRésumé :
碩士國立臺灣大學
機械工程學研究所
91
Logistics is a kind of knowledge that integrates science and sociology. It collects human experiences, intuition, judgments and quantitative analysis that result to a logical decision. To add logistic support consideration at the first stage of systematic design period may effectively increase reliability, maintainability and availability of a system. Thus decreases operation and support cost of that system. Most of the previous research focused on how reliability, maintainability and availability affect a logistic system. However, life cycle cost (LCC) was not included to magnify the results. In long-term observation, operation and support costs greatly affect life cycle cost. Thus lead to the interest of analyzing the effectiveness of logistic parameters to the operation and support costs. This work analyze reliability, maintainability and availability that affect operation and support costs. Referring to USA MIL-STD-1388-2B specification, some major items will be selected so as to establish operation and support costs of a system. A folklift vehicle is chosen as a case study to understand its performance.
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Lin, Yu-Chi, et 林于祺. « Investigation of Operating Parameters for Liquid Desiccant Dehumidification Process ». Thesis, 2018. http://ndltd.ncl.edu.tw/handle/zr8c7n.
Texte intégralRésumé :
碩士國立臺灣大學
生物產業機電工程學研究所
106
Compared with solid desiccant dehumidification systems, liquid desiccant dehumidification systems are characterized by the low regeneration temperature, flexible regeneration time, and separable dehumidification and regeneration unit. Liquid desiccant dehumidification systems with thereafter cooling devices, which come with lower operating cost, lower-grade energy demand, and better performance in air quality and humidity control, could be an alternate for air conditioning. Therefore, there is great development potential in liquid desiccant dehumidification systems. A large liquid desiccant dehumidifier has been constructed in this study. The parameters affecting the mass transfer of liquid desiccant have been discussed. The additional measurement system and the indicators for desiccant carry-over have been made and established. Vapor pressures of the mixed liquid desiccant aqueous solution reported in recent years have been measured in order to find the optimum mixing ratio for cost reduction. Finally, a small liquid desiccant dehumidifier has been constructed to test some more expensive liquid desiccant solutions. In this study, with the CFD results in the large liquid desiccant dehumidifier, the additional measurement device with a height of 200 mm was designed and used in the system for the carry-over problem. The KDM421 demister was used on dehumidifier experiments because of the high average wind speed and the low degree of droplet residue. For the large and small dehumidifiers, various operating parameters such as air flow rate, inlet air temperature, and so on were explored. The performance of the large dehumidifier with lithium chloride solution was equivalent to a commercial dehumidifier with the dehumidifying capacity of 19.48 L/d and the energy factor of 2.50 L/kWh, falling on the second level of dehumidifier energy efficiency grade. The experimental results of calcium chloride, lithium chloride and potassium acetate solutions in the small dehumidifier show that the surface vapor pressure of the liquid desiccant solution is strongly related to the moisture removal rate in air. Regarding the vapor pressure measurement of the mixed liquid desiccant solutions, the vapor pressure of the CaCl2+LiCl and LiCl+MgCl2 solutions both decreases with the increase of lithium chloride proportion. The vapor pressure of the LiBr+CaCl2 solutions increases with the increase of lithium bromide proportion. About the cost of mixed solutions, the cost of the CaCl2+LiCl solution increases with the increase of lithium chloride proportion. According to the cost and vapor pressure of the CaCl2+LiCl solution, the optimum ratio is 70% CaCl2+ 30% LiCl. Because the magnesium chloride used is more expensive than the lithium chloride, the cost of LiCl+MgCl2 solution decreases with the increase of lithium chloride proportion. The cost of the LiBr+CaCl2 solution increases with the increase of lithium bromide proportion.
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Chen, Yu-Kuang, et 陳昱光. « Experimental Study of the Operating Parameter for Ionizer ». Thesis, 2011. http://ndltd.ncl.edu.tw/handle/30795290048086178379.
Texte intégralRésumé :
碩士國立中央大學
工業管理研究所碩士在職專班
99
As the advanced technology development of Integrated Circuit (IC) and in order to increase the circuit efficiency, the circuit channels become shorter and the floodgate extremely oxide layers become thinner which results in the tolerance of electrostatic discharge (ESD) for electronic components become lower. As for the manufacturing environment of electrostatic and sensitive components, the requirement will be more careful. The process of manufacturing, fabrication, test and transportation for electronic products which will be because of the incomplete grounding system, miss operation or no proper prevention action for static charge to result in the ESD, product circuit damage or low reliability. The ESD control program except grounding system and material choice, the ionizer can neutralize the static charge on insulated objects. The operating parameter of ionizer includes power output, pulse time, overlap and balance. The charged plate monitor (CPM) is used to measure the positive discharge time, negative discharge time, high peak offset voltage and low peak offset voltage. In this research, the factorial design, central composite design, response surface methodology and desirability function were used to investigate the most significant factor (Balance) and optimum operating parameter (Power Output =70%、Pulse Time=0.955、Overlap=21.72%、Balance=53.1). Based on the statistical analysis and conditionality, the results have provided much valuable information on the setting method.
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Diltz, Robert. « Investigation on bioreactor operating parameters for optimum microbial hydrogen production ». 2006. http://etd.lib.fsu.edu/theses/available/etd-11132006-145751.
Texte intégralRésumé :
Thesis (M.S.)--Florida State University, 2006.Advisor: Bruce R. Locke, Florida State University, College of Engineering, Dept. of Chemical and Biomedical Engineering. Title and description from dissertation home page (viewed Jan. 23, 2007). Document formatted into pages; contains viii, 52 pages. Includes bibliographical references.