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EFFECTS OF TEMPERATURE ON THE SERVICE-LIFE OF LANDFILL LINERS AND POTENTIAL TEMPERATURE CONTROL STRATEGIESHOOR, AZADEH 10 August 2011 (has links)
Landfill facilities are required to have a barrier system that will limit escape of contaminants to groundwater and surface water for the contaminating lifespan of landfill. Heat generated by the biodegradation of waste and chemical reactions in landfills reduces the service-life of geomembranes by accelerating the ageing process of high-density polyethylene. It may also lead to the desiccation of clay components of the liners.
Four considerations with respect to the evaluation of the potential effects of liner temperature on the service-life of liners and the potential control of liner temperature are examined. For the first time, the likely temperature and service-life of a secondary geomembrane in a double composite lining system is predicted. It is shown that, in some cases, the temperature is likely to be high enough to substantially reduce the service-life of the secondary geomembrane. The possible effectiveness of using tire chips as passive thermal insulation between the primary and secondary liners, as well as traditional soil materials, is then explored. For the barrier system and contaminant examined, the results show that tire chips could potentially lower the temperature of the secondary geomembrane sufficiently to significantly extend its service-life. However, the use of tire chips brings about other practical issues, which are also discussed in this study. An active alternative method of controlling the increase in the landfill liner temperature is then examined. This approach, which is inspired by geothermal heat pumps, involves an array of cooling pipes beneath the waste. Numerical modelling showed that the hypotetical introduction of the cooling pipes resulted in a reasonable decrease in liner temperature. It is suggested that the proposed technique warrants further consideration. Finally the conditions that may lead to the desiccation of geosynthetic clay liners used in composite liners due to waste generated heat are examined and recommendations regarding possible means of mitigating the effects of heat on the performance of GCLs are presented. For example, numerical modelling shows that the hydration of GCL prior to waste placement, liner temperature, overburden stress, depth to aquifer and moisture content and grain size of subsoil affect desiccation. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2011-07-31 07:34:33.165
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Considerations in the Design of Barrier Systems for Landfills and LagoonsVerge, ASHLEY 01 October 2012 (has links)
A literature review of municipal solid waste landfill design was conducted to provide the knowledge base for development of an environmental decision support system (Landfill Advisor). Landfill Advisor integrates the current knowledge of barrier systems into a software program to assist in landfill design. The choices available for each liner component (e.g., drainage layer, geomembrane liner, compacted clay liner, geosynthetic clay liner) and their suitability for different situations (e.g., final cover, base liner, lagoon liner) are presented. Landfill Advisor covers both the design and related operational issues for municipal solid waste landfills, with consideration given to the interactions between components, operating conditions, and the natural environment with a view to maximization of long-term system performance. Unique to Landfill Advisor, the service life of each engineered component is estimated based on results from the latest research.
Original research is also presented on the risk of geosynthetic clay liner (GCL) desiccation in low stress applications such as solar ponds. Numerical modelling was undertaken using a thermo-hydro-mechanical model with parameters that were developed and verified by comparison to previously reported laboratory data. A parametric study was performed to establish recommendations for future investigation. The water retention curve of the GCL was found to have a significant effect on the conditions that are expected to cause desiccation. The temperature coefficient of the water retention curve was also found to have a significant effect, yet this parameter is not well defined. Poisson’s ratio was found to affect the risk of desiccation in proportion to the applied stress. As reported by previous researchers, the initial degree of saturation of a GCL was found to be important to desiccation; however, the effect is diminished at low applied stress. / Thesis (Master, Civil Engineering) -- Queen's University, 2012-09-28 18:52:20.106
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Ionizing Electron Incidents as an Efficient Way to Reduce Viscosity of Heavy Petroleum FluidsAlfi, Masoud 2012 August 1900 (has links)
The dependence on oil and the fact that petroleum conventional reservoirs are becoming depleted direct attentions toward unconventional-and harder to access-reservoirs. Among those, heavy and extremely heavy oil reservoirs and tar sands form a considerable portion of all petroleum resources. Conventional thermal and thermocatalytic refining methods are not affordable choices in some cases, as they demand a considerable energy investment. On the other hand, electron irradiation, as a novel technology, provides more promising results in heavy oil upgrading.
Electron irradiation, as a method of delivering energy to a target molecule, ensures that most of the energy is absorbed by the molecule electronic structure. This leads to a very efficient generation of reactive species, which are capable of initiating chemical reactions. In contrast, when using thermal energy, only a small portion of the energy goes into the electronic structure of the molecule; therefore, bond rupture will result only at high energy levels.
The effect of electron irradiation on different heavy petroleum fluids is investigated in this study. Radiation-induced physical and chemical changes of the fluids have been evaluated using different analytical instruments. The results show that high energy electron particles intensify the cracking of heavy hydrocarbons into lighter species. Moreover, irradiation is seen to limit any post-treatment reactions, providing products of higher stability. Depending on the characteristics of the radiolyzed fluid, irradiation may change the distribution pattern of the products, or the radiolysis process may follow the same mechanism that thermal cracking does.
In addition to that, we have studied the effectiveness of different influencing variables such as reaction temperature, absorbed dose values, and additives on radiolytic reactions. More specifically, the following subjects are addressed in this study:
*Radiation?induced chain reactions of heavy petroleum fluids
*Complex hydrocarbon cracking mechanism
*High and low temperature radiolysis
*Synergetic effects of different chemical additives in radiolysis reactions
*Time stability of radiation products
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Επίδραση εξωτερικών παραμέτρων στις χαρακτηριστικές ιδιότητες ηλιακών πλαισίων τύπου CISΧριστοδούλου, Μαρία 19 January 2010 (has links)
Αντικείμενο της παρούσας διπλωματικής εργασίας, είναι η μελέτη της
συμπεριφοράς φωτοβολταϊκού πλαισίου λεπτής ταινίας CIS, σε πραγματικές
συνθήκες λειτουργίας. Μελετάται η επίδραση διάφορων εξωτερικών παραγόντων
και κυρίως της θερμοκρασίας, της ηλιακής ακτινοβολίας και της σκίασης.
Με στόχο την εκτίμηση της παραγόμενης DC ισχύος σε διάφορες συνθήκες
λειτουργίας., έχουν πραγματοποιηθεί μετρήσεις ρεύματος-τάσης στο χώρο του
Πανεπιστημίου Πατρών, σε φωτοβολταϊκό πλαίσιο CIS ονομαστικής ισχύος 75W. Οι
μετρήσεις ήταν συνήθως ημερήσιες και καταγράφονταν οι τιμές για διάφορες
συνθήκες λειτουργίας και σε διαφορετικές εποχές του έτους. Με ένα μεταβλητό
φορτίο συνδεδεμένο με το εν λόγω φωτοβολταϊκό πλαίσιο, ήταν δυνατός ο
προσδιορισμός της χαρακτηριστικής I-V καμπύλης σε κάθε μέτρηση και ως εκ
τούτου, ο υπολογισμός του σημείου μέγιστης ισχύος. Για κάθε μέτρηση
καταγράφονταν, εκτός του ρεύματος και της τάσης, η λαμβανόμενη ηλιακή
ακτινοβολία, η θερμοκρασία αέρα καθώς και οι θερμοκρασίες στις δύο όψεις του
συλλέκτη.
Αρχικά, υπολογίζεται η απόδοση του πλαισίου σε διαφορετικές θερμοκρασίες
λειτουργίας ενώ σε αυτό προσπίπτουν ίδια ποσά της ηλιακής ακτινοβολίας. Επίσης,
μελετάται ποιες χαρακτηριστικές παράμετροι επηρεάζονται περισσότερο όπου
διαπιστώνεται πως η αύξηση της θερμοκρασίας προκαλεί μείωση της τάσης και μία
μικρή αύξηση του ρεύματος η οποία όμως, δεν είναι ικανή να αντισταθμίσει την
μείωση της τάσης, με αποτέλεσμα η αύξηση της θερμοκρασίας να επιδρά αρνητικά
στην απόκριση ισχύος.
Στη συνέχεια, γίνεται αντίστοιχος υπολογισμός και για την ηλιακή
ακτινοβολία όπου παρουσιάζεται η θετική της επίδραση στην απόδοση του
πλαισίου, ενώ ταυτόχρονα μελετάται η συμπεριφορά του CIS σε συνθήκες
ηλιοφάνειας αλλά και συννεφιάς. Κατά την επεξεργασία των αποτελεσμάτων
αυτών, ήταν δυνατός ο υπολογισμός μίας μέσης τιμής της αποδιδόμενης ισχύος
τόσο για τη θερινή όσο και για τη χειμερινή περίοδο.
Τέλος, προκαλώντας τεχνητή σκίαση στο 30% περίπου της επιφάνειας του
φωτοβολταϊκού πλαισίου κατά τη διάρκεια κάποιων μετρήσεων, υπολογίζεται το
ποσοστό μείωσης της παραγόμενης DC ισχύος, συγκριτικά με τις περιπτώσεις όπου
κάτω από τις ίδιες εξωτερικές συνθήκες, το πλαίσιο δεν σκιάζεται. / The objective of this diploma thesis, is to study the behavior of a thin film
photovoltaic module CIS, under real conditions of operation. The effect of various
exterior factors is studied and mainly the factors of temperature, solar radiation
and shading.
To estimate the produced DC Power in various conditions, measurements
has been took place at the University of Patras using a CIS photovoltaic module,
of 75W Maximum Power. Measurements were usually daily and were taken in all
seasons of year. With a variable load connected to the photovoltaic module, the
determination of the I-V curve was possible for each measurement and
consequently, the calculation of the Maximum Power Point could be made. At each
measurement, were noted the current, the voltage and also the received solar
radiation, the air temperature as well as the temperatures at the two sides of the
module.
At first, the output and the efficiency of the module in different
temperatures of operation are calculated , while the received solar radiation is the
same in every case. Also, it is studied witch parameters are more influenced by
increasing temperature and it is proved that voltage is decreased and current is a
little increased. However, the increasing current is not capable to compensate the
decreasing voltage, so the increase of temperature affects negatively the output
power and the efficiency.
Afterwards, a similar calculation has been made, studying the influence of
solar radiation at the characteristic parameters of the CIS photovoltaic module.
During these calculations, except the positive effect of solar radiation it is
presented the behavior of CIS in sunlight and also cloudy conditions. As a result,
an average output power of the module has calculated for the aestival and the
wintry period.
Finally, causing artificial shading in about the 30% of the module's surface,
it is determined the rate of reduction of produced DC power, comparatively the
case where the module is not shading under the same exterior conditions.
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Short and Long-Term Structural Health Monitoring of Highway BridgesZolghadri, Navid 01 May 2017 (has links)
Structural Health Monitoring (SHM) is a promising tool for condition assessment of bridge structures. SHM of bridges can be performed for different purposes in long or short-term. A few aspects of short- and long-term monitoring of highway bridges are addressed in this research.
Without quantifying environmental effects, applying vibration-based damage detection techniques may result in false damage identification. As part of a long-term monitoring project, the effect of temperature on vibrational characteristics of two continuously monitored bridges are studied. Natural frequencies of the structures are identified from ambient vibration data using the Natural Excitation Technique (NExT) along with the Eigen System Realization (ERA) algorithm. Variability of identified natural frequencies is investigated based on statistical properties of identified frequencies. Different statistical models are tested and the most accurate model is selected to remove the effect of temperature from the identified frequencies. After removing temperature effects, different damage cases are simulated on calibrated finite-element models. Comparing the effect of simulated damages on natural frequencies showed what levels of damage could be detected with this method.
Evaluating traffic loads can be helpful to different areas including bridge design and assessment, pavement design and maintenance, fatigue analysis, economic studies and enforcement of legal weight limits. In this study, feasibility of using a single-span bridge as a weigh-in-motion tool to quantify the gross vehicle weights (GVW) of trucks is studied. As part of a short-term monitoring project, this bridge was subjected to four sets of high speed, live-load tests. Measured strain data are used to implement bridge weigh-in-motion (B-WIM) algorithms and calculate the corresponding velocities and GVWs. A comparison is made between calculated and static weights, and furthermore, between supposed speeds and estimated speeds of the trucks.
Vibration-based techniques that use finite-element (FE) model updating for SHM of bridges are common for infrastructure applications. This study presents the application of both static and dynamic-based FE model updating of a full scale bridge. Both dynamic and live-load testing were conducted on this bridge and vibration, strain, and deflections were measured at different locations. A FE model is calibrated using different error functions. This model could capture both global and local response of the structure and the performance of the updated model is validated with part of the collected measurements that were not included in the calibration process.
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COLLISIONAL AND RADIATIVE RELAXATION IN SODIUM DIMER AND ARGON ATOM COLLISIONSHorton, Timothy Scott 02 December 2016 (has links)
No description available.
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Development of a Composite Concrete Bridge System for Short-to-Medium-Span BridgesMenkulasi, Fatmir 23 August 2014 (has links)
The inverted T-beam bridge system provides an accelerated bridge construction alternative for short-to-medium-span bridges. The system consists of adjacent precast inverted T-beams finished with a cast-in-place concrete topping. The system offers enhanced performance against reflective cracking, and reduces the likelihood of cracking due to time dependent effects. The effects of transverse bending due to concentrated wheel loads are investigated with respect to reflective cracking. Transverse bending moment are quantified and compared to transverse moment capacities provided by a combination of various cross-sectional shapes and transverse connections. A design methodology for transverse bending is suggested. Tensile stresses created due to time dependent and temperature effects are quantified at the cross-sectional and structure level and strategies for how to alleviate these tensile stresses are proposed. Because differential shrinkage is believed to be one of the causes of deck cracking in composite bridges, a study on shrinkage and creep properties of seven deck mixes is presented with the goal of identifying a mix whose long terms properties reduce the likelihood of deck cracking. The effects of differential shrinkage at a cross-sectional level are numerically demonstrated for a variety of composite bridge systems and the resistance of the inverted T-beam system against time dependent effects is highlighted. End stresses in the end zones of such a uniquely shaped precast element are investigated analytically in the vertical and horizontal planes. Existing design methods are evaluated and strut-and-tie models, calibrated to match the results of 3-D finite element analyses, are proposed as alternatives to existing methods to aid designers in sizing reinforcing in the end zones. Composite action between the precast beam and the cast-in-place topping is examined via a full scale test and the necessity of extended stirrups is explored. It is concluded that because of the large contact surface between the precast and cast-in-place elements, cohesion alone appears to provide the necessary horizontal shear strength to ensure full composite action. Live load distribution factors are quantified analytically and by performing four live loads tests. It is concluded that AASHTO's method for cast-in-place slab span bridges can be conservatively used in design. / Ph. D.
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Sizing Wind Tunnel Heater For High Enthalpy ConditionsSlavick, Justin M 01 June 2024 (has links) (PDF)
This paper determines the feasibility of adding a heater to an existing blowdown supersonic wind tunnel to unlock new high-enthalpy test applications, considering cost and power requirements at a variety of different states. This process includes both modeling the current range of test section properties in Cal Poly's blowdown wind tunnel and determining the new range of properties that a heat exchanger could induce. These results are verified with a computational fluid dynamics study. Additionally, sublimation and ablation properties of materials are explored to create appropriate models to study atmospheric re-entry once the heat exchanger is implemented.
It is found that adding a heater to the supersonic wind tunnel would significantly increase the test section temperature. Additionally, enough heat could be added without damaging the facility to surpass the vapor pressure of camphor and naphthalene at test section conditions, allowing for the tunnel to be used for sublimation and ablation applications. Using the tunnel with the variable Mach nozzle currently installed would induce minimum heater power requirements of 75kW for a Mach 4 configuration and 200kW for the testing Mach 3.13 condition to reach this vapor pressure. However, this power requirement can be significantly reduced by installing a new nozzle that would induce flow at a Mach number of 6-8. Liquefaction is found to be avoided at every test and Mach condition, even without any heat added, while condensation cannot be avoided at any configuration, regardless of nozzle used or heat added. Therefore, we recommend that a dryer be installed to help remedy these issues.
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Etude des propriétés viscoélastiques d'un nitrile chargé sous sollicitations cycliques : application à la prédiction de la durée de vie des pompes à rotor excentréGarnier, Pierre 04 October 2012 (has links)
L’étude de la durabilité des élastomères des stators des pompes Moineau a été menée en utilisant à la fois des simulations numériques, des essais thermomécaniques et des analyses physico-chimiques. Les simulations numériques ont eu pour principal objectif de permettre de déterminer la localisation et le niveau des maximums des champs mécaniques dans le stator. Les essais ont permis quant à eux de caractériser le comportement mécanique du matériau élastomère sous sollicitations mécaniques cycliques à différentes températures. Une première étude a permis d’analyser l’évolution de l’effet Payne en fatigue. Une seconde s’est concentrée sur l’analyse de l’effet de l’application d’un chargement thermomécanique sur l’évolution de la microstructure du matériau élastomère. / The study of the sustainability of the rubber, which is the main constitutive material of the Moineau pump stator, was carried out using finite element analyses, thermomechanical experiments and physic-chemical analysis. The numerical simulations were performed to identify the range and location of the maximal stress and strain within the pump stator. The experimental tests allowed to characterize the mechanical behaviour of rubber under cyclic solicitation at several temperatures. The first part of the study focused on the Payne effect during fatigue loading while the second dealt with the effect of a thermomechanical loading on the rubber microstructure evolution.
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[en] TEMPERATURE EFFECTS ON SOILS / [pt] EFEITO DA TEMPERATURA EM SOLOSCLAUDIO RABE 23 April 2001 (has links)
[pt] O presente trabalho apresenta um estudo do comportamento
mecânico de um solo argiloso e um solo residual, submetidos
a ensaios com temperaturas entre 20ºC e 70ºC.
O programa experimental envolveu ensaios de caracterização
(limites de Atterberg), ensaios de adensamento com
carregamento incremental (SIC), triaxiais não drenados
(CIU) e de cisalhamento direto.
Para a realização dos ensaios de limites de Atterberg, as
amostras foram previamente aquecidas em estufa. Para a
realização dos ensaios de adensamento, triaxiais e de
cisalhamento direto, foram desenvolvidos sistemas de
aquecimento, controle e distribuição térmica, para garantir
ao corpo de prova uma uniformidade da temperatura
preestabelecida.
Uma metodologia de calibração do sistema de aquecimento foi
desenvolvida para se determinar o tempo necessário para o
equilíbrio térmico dos solos. Houve também a preocupação
com a calibração prévia dos instrumentos eletrônicos da
prensa triaxial (transdutores e célula de carga) na
temperatura dos ensaios.
Na faixa de temperatura estudada, o preaquecimento não têm
influência nos resultados de limites do solo argiloso. Os
ensaios de adensamento revelaram que o aquecimento leva a
um aumento da compressibilidade do solo, assim como um
aumento da velocidade de adensamento. Nos ensaios
triaxiais, observou-se que o aumento da temperatura causa
um aumento da resistência dos materiais, além de reduzir o
excesso de poropressões gerado durante o cisalhamento não
drenado.
Os ensaios de cisalhamento direto confirmaram a tendência
de aumento da resistência observada nos ensaios triaxiais,
além de indicar uma redução da deformabilidade volumétrica
durante o cisalhamento. / [en] The subject matter of this thesis is the study of the
mechanical behavior of clay and residual soils subjected to
a series of tests with temperatures ranging from 20 to 70ºC.
The experimental program consisted of Atterberg limits,
consolidation tests with incremental loading (SIC),
triaxial consolidated undrained tests (CIU) and direct
shear tests on both soil types under saturated conditions.
Samples for Atterberg limit tests have been pre-heated in
oven to the specified temperature. Heating control and
thermal distribution systems have been specially developed
for insuring an homogeneous temperature throughout the
consolidation, triaxial and direct shear tests.
The thermal balance times for the two soils were achieved
by means of a calibration method developed for the heating
system. Transducers and load cell calibration were carefully
calibrated acording to the temperature range for the
testing program.
It may be concluded that pre-heating to temperatures below
70ºC has no influence on
the Atterberg limits results for both soils. Consolidation
tests have shown that heating on
samples leads to an increase in compressibility and also on
the coefficient of consolidation.
From the triaxial tests it was observed that an increase in
temperature leads to an increase in strength and to smaller
excess porepressures during undrained shear tests.
The increase in shear strenght with temperature observed on
triaxial tests was also confirmed by direct shear tests.
These effects were more significant in clay than in residual
soil.
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