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Thèses sur le sujet « Import penetration »
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1
Onaran, Özlem. « The effect of import penetration on labor market outcomes in Austrian manufacturing industry ». Inst. für Volkswirtschaftstheorie und -politik, WU Vienna University of Economics and Business, 2008. http://epub.wu.ac.at/1264/1/document.pdf.
Texte intégralRésumé :
This paper estimates the effects of imports on employment, wages, and the wage share in Austria for the period of 1990-2005 using panel data of manufacturing industry. Imports are disaggregated according to their origin and as final vs. intermediate imports. There is evidence of significant negative effects of imports on employment, wages and the wage share. Particularly workers in high skilled sectors experience negative effects. Offshoring to both Eastern Europe and the developed countries have a negative impact on employment, whereas offshoring to the East has a positive effect on wages, indicating the dominance of scope effects. (author´s abstract)Series: Department of Economics Working Paper Series
2
Jan, Nawawi Bin Mohammed. « Business strategies for firms in declining industries caused by low-cost import penetration ». Thesis, Loughborough University, 1995. https://dspace.lboro.ac.uk/2134/28270.
Texte intégralRésumé :
The major limitation of many studies on declining industries is the presumption that industrial decline is associated with the final stage of the industry life cycle. These studies often define the sample of their study as those firms where their dominant products are subjected to technological obsolescence and are experiencing a persistent decline in the demand of their products. Conversely, the current study identified factors that the cause of the shrinking in demand of the UK industries was not generally obsolete technology. The decline of UK industries was partly due to severe low cost import penetration that stimulated the shift in demand from the UK manufacturers to the cheaper imported products from the over-seas low cost manufacturers.
3
Van, Walsum Judith M. (Judith Margaretha) Carleton University Dissertation International Affairs. « The EC policy response to import penetration and foreign direct investment in the European semiconductor industry : a political economy analysis ». Ottawa, 1990.
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4
Moloto, Phineas Rameshovo. « Growth Trends in the South African Manufactured Export Industry ». Diss., University of Pretoria, 2005. http://hdl.handle.net/2263/28425.
Texte intégralRésumé :
Through empirical research the researcher gained an in-depth knowledge regarding the growth trends in the South African manufactured export industry as well as the factors determining the patterns of growth and champion industries. Finally, recommendations that may be used by relevant authorities and scholars were made. To researchers, a study at disaggregated level into the growth trends of each manufactured export sub-sector should be central to future research.Dissertation (MA (Economics))--University of Pretoria, 2005.
Economics
unrestricted
5
Olsen, Gregory Dana. « Experimental investigation into catastrophic failure of pressure vessels due to hypervelocity impact / ». Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3008411.
Texte intégral
6
Emanuel, Kevin. « Impact of high renewable penetration in a distribution network ». Thesis, Emanuel, Kevin (2019) Impact of high renewable penetration in a distribution network. Honours thesis, Murdoch University, 2019. https://researchrepository.murdoch.edu.au/id/eprint/52468/.
Texte intégralRésumé :
The growth of renewable energy, especially PV system has been accelerated in the past decades. With this growth, several problems have been identified that can interfere with the power quality on the distribution network. These problems include; voltage rise, voltage unbalance, voltage sag/swell, flickering, and harmonic issue. IEEE 13 bus distribution network has been chosen to be the base of this research due to its flexibility and it has been modeled in DigSILENT Power Factory. The results of the study shown that the identified problems were real, and it needs to be addressed before damages can be done to the equipment. The proposed solution to the network was to double feed the network. Double feeding is a solution that proposed an extra connection to the grid in the farthest node in the distribution network. The proposed solution has been tested and promising results were found. Overall the study has been helpful to test the capability of a distribution network to handle a various degree of PV production level and how double feeding affected the power quality of the network. More research in the network is needed, especially with a real distribution network involved as a real network will behave differently compared to the simulated network.
7
Ballew, Wesley D. « Taylor Impact Test and Penetration of Reinforced Concrete Targets by Cylindrical Composite Rods ». Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/34098.
Texte intégralRésumé :
We use the three-dimensional finite element code DYNA3D to analyze two problems: (a) the normal impact of a cylindrical monolithic or composite rod against a smooth flat rigid target, (commonly known as the Taylor impact test), and (b) the penetration of composite and monolithic steel cylindrical rods into reinforced concrete targets. The composite rod is made of either a steel or copper shell enclosing a ceramic. The ceramic and the steel are assumed to fail at a critical value of the effective plastic strain, whereas no failure is considered in the copper. The thermoviscoplastic response of steel and copper is modeled by the Johnson-Cook relation and the ceramic and concrete are assumed to be elastic-plastic. Values of material parameters in the constitutive relation for the reinforced concrete (RC) are derived by the rule of mixtures. Failure of a material is simulated by the element erosion technique for ceramic and steel, and element erosion along with stiffness reduction for the RC. The effect of the angle of obliquity of impact on the damage induced in the target is ascertained.
For the solid cylindrical copper rod impacting a smooth flat rigid target, the time history of the deformed length and the axial variation of the final diameter are found to match well with the experimental findings. For the composite rod, the diameter of the deformed impacted surface, the shape and size of the mushroomed region and the volume fraction of the failed ceramic material strongly depend upon the impact speed, the shell wall thickness and the thickness of the solid copper rod at the front end.
Some composite cylindrical rods impacting at normal incidence RC targets were found to buckle during the penetration process in the sense that their outer diameter at a cross-section close to the impacted end increased by at least 20%. For steel penetrators, the damage experienced increased as the nose shape got blunter and the angle of obliquity became larger whereas the damage induced to the target only increased with penetrator bluntness.
Master of Science
8
Stevens, John Boyet. « Finite Element Analysis of Adiabatic Shear Bands in Impact and Penetration Problems ». Thesis, Virginia Tech, 1996. http://hdl.handle.net/10919/36650.
Texte intégralRésumé :
We study axisymmetric deformations of depleted uranium (DU) and tungsten heavy alloy (WHA) rods impacting at normal incidence both a rigid, planar target and a thick, deformable steel target. Each deformable material is modeled as elastic thermoviscoplastic; the flow stress increases with an increase in the effective plastic strain and effective plastic strain-rate but decreases with a rise in the temperature. An objective of this work is to ascertain when and where a shear band, defined as a narrow region of rapid, intense plastic deformation, forms in each material subject to impact loading. The Taylor impact simulations show that shear bands form earlier in WHA than in DU for the material parameters used. In the penetration simulations, shear bands form continuously in the ejecta of the DU penetrator while only one shear band occurs in the WHA ejecta followed by more uniform deformations.
Note: In order to view the computer animations referenced in this thesis, one must have a QuickTime movie player and download the files named Ujce.mov Uz2e.mov Uz3e.mov Wjce.mov Wz2e.mov and Wz3e.mov from the same directory the "pdf" file resides in.Master of Science
9
Khastieva, Dina. « Energy Storage Impact On Systems With High Wind Energy Penetration ». Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1402063032.
Texte intégral
10
Blandin, Christopher. « Production of dielectric materials ». Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26568.
Texte intégralRésumé :
Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2009.Committee Chair: Colton, Jonathan; Committee Member: Schultz, John; Committee Member: Zhou, Min. Part of the SMARTech Electronic Thesis and Dissertation Collection.
11
Thanapisudwong, Thatchai. « The Impact of Raceway Mixing and Light Penetration on Algal Growth ». Ohio University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1479910640426105.
Texte intégral
12
Jiang, Tianci. « Impact & ; penetration studies simplified models and and materials design from AB initio methods / ». Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/10443.
Texte intégralRésumé :
In recent impact and penetration mechanical tests, steel projectiles (AISI4340) were impacted into targets like concrete with striking velocities (1200 m/s to 1500 m/s). Results indicated a material removal from the nose of the projectile, phase changes of the projectile materials, a reduction in the length of the projectile, and a blunting of the nose shape. These observations cannot be explained by current theories and numerical integration code that are used to study impact and penetration mechanics.
Thus, the objectives of the thesis research are to (a) formulate and characterize the mechanisms responsible for the material erosion of the impacting projectile and the mass loss from the nose region; and (b) to determine the physical properties of alloy steels that are important to penetration mechanics from ab initio methods. The results can be used to design new projectile materials that can provide the desired penetration characteristics.
These objectives are accomplished by investigating two related problems. The first problem is to formulate simplified models that can explain the penetration mechanics. The new models include the varying cross-section nose, changes of yield stress behind the shock wave and high strain rate phase transitions. Nose erosion effects, and time-dependent penetration path can be determined by integrating ODEs. A cavity expansion theory model is used to obtain the target resistance that is responsible slowing and deforming the penetrating projectile.
The second problem concerns the determination of the constitutive relations from ab initio methods. The equation of state (EOS) and magnetic moments for alloy steels are investigated by using a special quasirandom structure technique and ab initio methods. Specifically, EOS for an interstitial disordered alloy Fe1-x-yNixCy is developed. First, the EOS of iron and phase transition of iron are studied and validated. Second, Nickel is considered to investigate the substitutional disordered alloy Fe1-x-yNixCy. Third, Carbon is placed at an interstitial position in the substitutional disordered alloy. These investigations will form foundation for future work involving new projectile with steel nose and shank made of multifunctional structural energetic materials.
13
Little, Sally. « The impact of increasing saline penetration upon estuarine and riverine benthic macroinvertebrates ». Thesis, Loughborough University, 2012. https://dspace.lboro.ac.uk/2134/9737.
Texte intégralRésumé :
Coastal and estuarine systems worldwide are under threat from future global climate change, with potential consequences including increased penetration of tidal driven salt water into estuarine surface waters. In coastal climate change research this issue has been neglected, despite increases in salinity potentially detrimentally impacting upper estuarine and riverine ecosystem function worldwide. In this research the first direct attempt is made at predicting the impact of future climate-driven increases in saline penetration upon estuarine and riverine benthic macroinvertebrate communities through the acute salinity tolerances of selected species. Two study estuary-river systems were selected based upon their perceived susceptibility to future increases in saline penetration. These estuaries exhibited dynamic tide and salinity profiles with large salinity ranges recorded over a tidal cycle and significant differences in saline penetration extents between low (summer) and high (winter) freshwater river discharge conditions. Salinity was shown to be the dominant environmental variable driving benthic macroinvertebrate species distributions in both estuaries; however additional environmental factors were shown to have locally dominant effects (i.e. sediment grain size). Laboratory and field based salinity toxicity experiments suggested that the tolerance of euryhaline-marine and brackish water species to reductions in salinity corresponded well to tolerance values in published literature. In contrast limnic derived species exhibited greater salinity tolerance under laboratory and field tidal cycle conditions than those published. For all test species, actual field distributions did not reflect distributions anticipated by saline tolerances alone, likely due to the effects of additional biotic and abiotic factors experienced under field conditions. The macroinvertebrate species salinity tolerances did not account for actual field distributions with sufficient accuracy to allow for precise prediction of future distribution patterns under projected saline penetration profiles due to the influence of additional environmental factors. Under the high greenhouse gas emissions climate scenario (SRES A1FI) for the years 2020, 2050 and 2080, projected relative sea level rise was shown to result in an increase in both the upstream extent of saline penetration and gradient of maximum salinity zones in both estuaries. However these increases were moderate even under worst-case conditions (0.32 km and 0.15 km) and unlikely to result in large-scale changes to the benthic macroinvertebrate community. However, in addition to relative sea level rise, predicted changes to freshwater river discharge (climatic and anthropogenic induced) and channel morphology could result in significant increases in the upstream extent of saline penetration predicted for projected sea level rise alone. This could result in critical consequences for estuarine and riverine ecology and ecosystem function across all trophic levels. A conceptual model exploring the potential ecological effects of both increases in saline penetration and changes to the estuarine system (anthropogenic and climatic) was developed, and implications for the future management of estuarine and riverine environments were identified.
14
Isaac, Nithin. « Economic impact of captive solar technology and an ideal grid penetration level ». Diss., University of Pretoria, 2017. http://hdl.handle.net/2263/59842.
Texte intégralRésumé :
Since the 2008 energy crisis, the national utility has been under stress to meet the country's electrical demand. Moreover, the costs of building new conventional power stations and the operation and maintenance costs of existing ones are taking a toll on the economy. The utility has hence resorted to hiking electricity tariffs. This combination of rising electricity prices and decreasing costs of photovoltaic (PV) technology have hence led a number of households to cover part of their electricity demand by self-produced captive solar PV technology. Reliable supply of energy is the backbone of a growing economy, hence the integration of captive solar PV technology, and self-generation seems to be growing on the back of an impending energy crisis. Although the integration of cleaner energy sources is good, uncontrolled or over penetration of captive solar technology could become a threat to the utility.Mini Dissertation (MBA)--University of Pretoria, 2017.
nk2017
Gordon Institute of Business Science (GIBS)
MBA
Unrestricted
15
Tsholoba, Mziwamadoda Timothy. « Impact assessment of high penetration of rooftop PV in municipal electrical networks ». Thesis, Cape Peninsula University of Technology, 2019. http://hdl.handle.net/20.500.11838/3073.
Texte intégralRésumé :
Thesis (MEng (Electrical Engineering))--Cape Peninsula University of Technology, 2019There is an increasing global trend of grid connected distributed generation, mainly based on renewable energy sources such as wind and photovoltaic (PV) systems. The proliferation of these intermittent energy sources into the existing networks may subject the network into technical challenges such as voltage rise, equipment over-load, power quality and protection scheme violations. With increased PVDG (mainly rooftop PV) uptake occurring mostly on Low Voltage (LV) feeders, characterised by lack of network visibility and controllability, these technical challenges may be exac-erbated. In the absence of government incentive, current uptake of rooftop PVDG is reliant on customer preference and financial means. Thus make PVDG integration on the network be randomly placed and sized, of which the network distribution operator (NDO) will have no control over. The lack of regulations and interconnection studies conducted on South African networks has resulted in a growing concern amongst util-ities on how the increasing customer-owned rooftop PV systems uptake will impact the existing networks. This study aims to investigate technical impact high penetration of rooftop PV sys-tem will have on the existing LV networks. The load flow (LF) computation is pivotal in determining power system state when subjected to high penetration of rooftop PV. Monte-Carlo based Probabilistic Load Flow (PLF) was proposed and input variables were modelled using Beta probabilistic distribution function (PDF). The proposed im-pact assessment framework was applied on real LV urban residential network situated in Cape Town, South Africa. Simulations were conducted on DIgSILENT PowerFac-tory and the PDF for input variables (Load demand and PV generation) were derived from historic data. Four scenarios were simulated and system performance parameters were recorded such as; voltage magnitude, voltage unbalance factor and equipment thermal loading. Simulation results in the test network indicated thermal loading violation as the main limiting factor in urban residential network. PV system topology (either three-phase or single phase) proved to have significant effect on network hosting capacity, were higher PV penetration can be achieved for a three-phase system. Penetration level as low as 12% were recorded, which is significantly lower than the prescribed guidelines in simplified criteria in NRS097-2-3 standard and therefore raises a concern on the relevance of this standard on all types of networks (in urban network in particu-lar). However, penetration level above NRS097-2-3 limits may be achieved depending on feeder characteristics.
16
Mubaraki, Abesh Sorab. « IMPACT OF PHOTOVOLTAIC SYSTEM PENETRATION ON THE OPERATION OF VOLTAGE REGULATOR EQUIPMENT ». DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/965.
Texte intégralRésumé :
The growing popularity of photovoltaic (PV) generation systems leads to an increase in the number of residential and commercial grid-tied PV systems that interconnect to the distribution circuit. This affects the characteristics of the distribution circuit; for example, the assumption that the voltage profile of a radial line decreases down-stream becomes invalid because of the addition of the PV system on the line. This poses new challenges when setting the parameters of voltage regulating devices. Add to that the fact that PV systems are intermittent, especially on cloudy days, which make the line even more difficult to regulate, and the number of switching occurrences of the regulating devices increases, thus accelerating wear-and-tear to the utility’s equipment.
The objective of this thesis is to develop an index which qualitatively indicates the impact of PV system(s) on operation, efficiency, reliability, and lifetime of voltage regulation equipment. Tests on the proposed index will be performed on several cases including circuits containing state-of-the art methods that integrate PV systems with minimum impact to utility equipment. Investigation of methods to further mitigate equipment wear by selecting the best interconnect point on the circuit will also be conducted to test the proposed index. The development and validation of the proposed index will entail power system modeling and simulation of distributed generation using PSCAD. The proposed index resulted from this study will provide a useful tool to allow utility companies pick the optimum locations for distributed generation to minimize their negative impact on the distribution lines as well as to determine the need for extra mitigation equipment.
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Ramirez, Amanda Christine. « Microstructural properties associated with adiabatic shear bands in Ti-6A1-4V deformed by ballistic impact ». To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2008. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
Texte intégral
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Kurt, Burcak. « Impact Of High-level Distributed Generation Penetration On The Transmission System Transient Stability ». Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/2/12611199/index.pdf.
Texte intégralRésumé :
This thesis investigates the impact of high-level penetration of distributed generation especially from the renewable energy sources on the transient stability of the transmission system.
Distributed generation is a source of electric power connected to the distribution network or on the consumer side. It is expected that distributed generation grows significantly by the increasing environmental concerns and deregulation in the market. As soon as the increasing penetration level, distributed generation starts to influence the distribution system as well as the transmission system.
To investigate the impact of distributed generation with different penetration levels on the transmission system transient stability, simulation scenarios are created and simulations are run on the basis of these scenarios by the implementation of the different distributed generation technologies to the &ldquoNew England&rdquo
test system. Stability indicators are observed to assess the impact on the transient stability. Results are presented throughout the thesis and the impact of the different distributed generation technologies and the different penetration levels on the transient stability is discussed by comparing the stability indicators.
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Tanner, William Graydon. « Meteoroids and space debris hypervelocity impact penetrations : the role of hydrocodes ». Thesis, University of Kent, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319235.
Texte intégral
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Benoit, Paul Daniel. « Impact of on-site physician care in penetrating trauma ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0022/MQ50721.pdf.
Texte intégral
21
Wadagbalkar, Pushkar. « Real-time prediction of projectile penetration to laminates by training machine learning models with finite element solver as the trainer ». University of Cincinnati / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1592169428128864.
Texte intégral
22
Cole, Robert Paul. « Ballistic Penetration of a Sandbagged Redoubt Using Silica Sand and Pulverized Rubber of Various Grain Sizes ». Scholar Commons, 2010. http://scholarcommons.usf.edu/etd/3565.
Texte intégralRésumé :
The basis of this work is to find how varying the grain size of materials contained in sandbags (sand and crumb rubber) effects the ballistic penetration of the projectiles from both the 7.62x39mm (308-short), and 9mm Luger cartridges. The sandbags were stacked in a pyramidal stacking configuration according to military specifications in order to simulate a section of a sandbag barrier or redoubt as would be seen on the battlefield. The projectiles were fired at the targets, and the velocity and penetration data was recorded. The results concern both military and civilian applications alike. The 7.62x39 round was found to experience more fragmentation as grain size increased, and was also found to have, on average, the least amount of penetration into the largest grains. The 9mm round was found to suffer negligible deformation in all of the various sizes of materials, and when fired at the two types of materials, showed a steady trend of decreasing penetration depth with increasing grain size. The sand had a wearing effect on the projectiles leaving them scared or fragmented and deformed while the rubber kept the rounds in pristine condition.
23
Ntsadu, Ntlahla. « Impact assessment of large-scale penetration of permanent magnet synchronous generators on power quality ». Master's thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/26891.
Texte intégralRésumé :
Wind power generation has gained a large share in the renewable energy market over the past few years. This study investigates the impact of large scale penetration of permanent magnet synchronous generator (PMSG) based wind turbines on power quality of the grid. PMSGs are attractive due to the absence of a gearbox in the drive-train, which results in lower maintenance costs and higher reliability. Moreover, the advancements in power electronics have facilitated PMSGs to generate optimal power at varying wind speed conditions. This is achieved through the use of maximum power point tracking algorithms. The drawbacks of PMSG-based wind energy systems are that they inject harmonics into the network and cause flicker as well as other power quality issues. Despite these disadvantages, the grid code requires that PMSGs stay connected to the grid even under grid disturbances. This is because the reactive power control capability of PMSG-based wind energy systems can actually assist with voltage support. It will be shown in this study that disconnecting large scale PMSGs based wind turbines during grid disturbances has a detrimental effect on transient stability of the grid. This study will show that PMSG-based wind energy systems improve transient stability and assist in voltage support through reactive power control. Moreover, the impacts of large scale PMSG based wind turbines on power quality of the grid can be reduced by various means, which are also addressed in the study.
24
Snow, Camilla J. « Impact of Beaver Ponds on Stream Temperature and on Solar Radiation Penetration in Water ». DigitalCommons@USU, 2014. https://digitalcommons.usu.edu/etd/3858.
Texte intégralRésumé :
Beaver dams alter streams characteristics in a way that promotes the diversity of aquatic species and provides a wide distribution of temperatures within beaver ponds. In order to quantify the spatial distribution of these temperatures, a process-based temperature model was developed for a beaver pond in Northern Utah. This model provided insight into the processes and characteristics that are driving these temperatures. Solar radiation is one of these processes that is often the primary driver of stream temperature. There is a need to develop methods to measure the fate of solar radiation within the water to better represent solar radiation within stream temperature models. Black-body pyranometers are instruments that measure solar radiation in air, but require corrections for use underwater. Studies were conducted investigating methods for correcting these instruments. Based on the results of these studies it is suggested that these corrections are dependent on the spectrum of the light source and that the instrument needs further corrections when the light source is measured from different angles; therefore there is a need for further investigation into pyranometer corrections in order to measure the fate of solar radiation in natural water bodies. Combined, this research provides methods and suggests additional research opportunities for more accurately quantifying and predicting stream temperatures for waters impacted by beaver.
25
Lundberg, Patrik. « Interface Defeat and Penetration : Two Modes of Interaction between Metallic Projectiles and Ceramic Targets ». Doctoral thesis, Uppsala University, Department of Engineering Sciences, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4641.
Texte intégralRésumé :
Ceramics constitute an important group of low-density armour materials. Their high intrinsic strength makes it possible to design ceramic armour systems capable of defeating projectiles directly on the ceramic surface. This capability, named interface defeat, signifies that the projectile material is forced to flow radially outwards on the surface of the ceramic without penetrating significantly.
This thesis presents impact experiments between long-rod projectiles and ceramic targets. The projectile/target interaction was studied using flash X-ray technique. Transition velocities (the impact velocity at which interface defeat can no longer be maintained and penetration starts) were estimated for different combinations of metallic projectiles and ceramic targets and compared to critical velocities estimated on a theoretical basis. Replica scaling experiments were also performed in order to investigate the possible influence of scale.
All ceramic materials tested showed a distinct transition from interface defeat to penetration. Experiments with different silicon carbides showed that the transition velocity correlated better with the fracture toughness than with the hardness of the ceramic materials. For conical projectiles, penetration occurred along a conical surface crack and at a lower transition velocity than that observed for cylindrical projectiles. Experiments with unconfined alumina targets in different scales showed only a slight increase in dimensionless final penetration with length scale.
A unique transition velocity seems to exist for each combination of projectile, target material and target configuration. This velocity was found to depend on both the strength (hardness) and the brittleness (fracture toughness) of the ceramic. The lower transition velocity of conical projectiles compared with cylindrical ones is mainly due to the radially expanding load and the penetration of projectile material into surface cracks. The results of the experiments in different scales indicate that replica scaling is valid for penetration in ceramics.
26
Olatoke, Abraham Oladele. « Impact of high penetration of renewable energy sources on the relay coordination of distribution system ». Thesis, Brunel University, 2016. http://bura.brunel.ac.uk/handle/2438/12979.
Texte intégralRésumé :
The rate at which the integration of distributed generation (DG) penetrates the public power supply has started to put various demands on the distribution system, since they are directly connected to the network. Distribution level protection is based on a time-overcurrent design. The design is to clear faults with as little impact and minimum time on the equipment and the customer. The increasing demands placed by grid services on the DGs, especially the PV types have a serious impact on the distribution system. For example, special protective devices are required to prevent the risk of danger in the event of mains interference. In this thesis, the main focus was on the contribution of fault currents to the distribution networks, and how the high penetration of DGs especially the renewable energy resources (R.E.S.) types affect the coordination of overcurrent (O.C.) protection. In view of the changes in the international regulations, the DGs are expected to stay connected and perform grid-related control functions, instead of shutting down at the first sign of a fault. This problem becomes more acute when the DGs stay connected during faults, known as voltage ride through (VRT). This thesis presented its findings on the impact of the DGs of various types of DGs (synchronous generator, asynchronous and power electronic) on the protection coordination by the high increase of fault currents, and the mitigation techniques of the impact of the inverter interfaced DGs (whose fault current contribution was not so high) on the overcurrent protection. The impact on system’s over-current protection coordination in such hybrid AC and DC microgrid, how the fault current changes by the high penetration of DGs in the hybrid microgrid and their effects on the protection over-current coordination were presented, as the name microgrid was adopted for networks having a point of common connection (PCC). The inverter interfaced-equipment were never in the conventional systems, the few that were there were all on the load side of the distribution system. The inverter interfacing DGs (PVs) and the synchronous types are the types of DGs that affect over-current protection of the distribution system and these were mitigated accordingly, considering the first few cycles of the fault events of the ride through capabilities. The analysis of the different penetration levels of the DGs in an existing 33kV in the Nigerian distribution network, (CocaCola-Challenge Industrial feeder) was thoroughly analysed, for less than 20%, more than 60% and 100% of the feeder load. Most of the DGs, presently existing in that network are the synchronous types, but they are only used as standby sources of power, and the renewables (RES) like the photovoltaics (PV), run of flow (RoF) Hydo and the wind turbine generators (WTG) are proposed additions. The objective of this thesis was to explain the fundamentals of distribution generation (DG) and especially the RES, in relation to distribution protection relay coordination to see why there should be urgency in carrying out the study especially in a developing environment where the grid is unstable, the load is rapidly expanding and RES is intermittent. The radial distribution system (DS) with high penetration of DG was introduced. The motive was to critically investigate protection coordination problems and the solutions to the problems. The main objective was to optimally recommend the type, size and location of the DG for an actual distribution feeder in an unstable environment where the grid supply is not steady. The effect of 100% and above of feeder load penetration on such feeders formed the objective of this research. The literature review which was for investigating in greater details the technical aspects of the operation and control of the high penetration of RES in the distribution system were thoroughly analysed. The review of the existing radial distribution protection system and the effects of high penetration of DG on the protective relaying were thoroughly investigated. The issues of power electronic based inverters and the protection coordination problems, were investigated. The protection coordination as regards to fault level changes and grounding, intentional and un-intentional islanding were major important aspects which were treated in the technical review.
27
Renström, René. « Impact of Metallic Projectiles on a Ceramic Target Surface : Transition Between Interface Defeat and Penetration ». Doctoral thesis, Uppsala universitet, Hållfasthetslära, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7264.
Texte intégralRésumé :
The purpose of this thesis is to gain understanding of the load on flat target surfaces produced by projectile impact. Models are proposed from which upper and lower bounds can be derived for the transition be-tween interface defeat and normal penetration. It is shown that the dominating contribution to the normal load is generally provided by the hydrodynamic pressure due to the effect of inertia. In addition it is shown that the contributions from yield strength and compressibility are also significant. For a cylindrical tungsten alloy projectile at an impact velocity representative of to-day’s ordnance velocities, the contributions to the load intensity on the axis of symmetry from yield strength and compressibility are shown to be 15% and 3.4%, respectively, of that of inertia. Impact tests have shown that for conical projectiles transition from interface defeat to penetration occurs at a significantly lower impact velocity than for cylindrical projectiles. In order to better understand the influence of projectile shape, a conical projectile in axi-symmetric impact is studied by use of an analytical model for self-similar flow, and the results obtained are compared to results of numerical simula-tions. It is shown how the maximum load intensity, and the position of the maximum, depends on the apex angle. For an apex angle of 90º, the maximum load intensity is found to be almost three times that pro-duced by a cylindrical projectile with the same impact velocity. This maximum occurs well off the axis of symmetry and is 20% larger than the load intensity at this axis. Both the self-similar model and the nu-merical simulations show that the contribution to the load intensity from compressibility is positive below and negative above an apex angle of around 80º. The contribution of yield strength to the load in-tensity at centre of impact depends only weakly on the apex angle and is therefore similar to that of a cylindrical projectile.
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Bartus, Shane D. « Simultaneous and sequential multi-site impact response of composite laminates ». Birmingham, Ala. : University of Alabama at Birmingham, 2006. http://www.mhsl.uab.edu/dt/2006p/bartus.pdf.
Texte intégralRésumé :
Thesis (Ph. D.)--University of Alabama at Birmingham, 2006.Additional advisors: James S. Davidson, Derrick R. Dean, Gregg M. Janowski, Mark L. Weaver. Description based on contents viewed Jan. 24, 2007; title from title screen. Includes bibliographical references (p. 235-246).
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Tapia-Ahumada, Karen de los Ángeles. « Understanding the impact of large-scale penetration of micro combined heat & ; power technologies within energy systems/ ». Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/67759.
Texte intégralRésumé :
Thesis (Ph. D.)--Massachusetts Institute of Technology, Engineering Systems Division, 2011.Cataloged from PDF version of thesis. Page 304 blank.
Includes bibliographical references (p. 247-254).
Significant energy challenges today come from security of supply and environmental concerns. Those surpass the quest for economic efficiency that has been the primary objective until recent times. In an intensive fossil-fuel energy world, it is critical to find more effective ways of using the existing resources and of identifying technologies that can improve the sustainability of the energy model. Both, distributed energy resources and renewable-based electricity generation technologies are considered, by energy experts and also policymakers, to be essential for this purpose. Co-generation of electricity and heat at the residential level, known as micro-CHP, is an attractive alternative because of the potential for enhancing energy efficiency, reducing GHG emissions, and improving the utilization of primary energy resources. This thesis aims at quantitatively assessing the impacts of a large-scale penetration of micro-CHPs within an energy system. Based on system-wide and residential metrics, this work intends to understand whether or not this technology is a valuable contribution to social welfare. For this purpose, a methodology is developed to integrate increasing numbers of micro-CHPs into a system's generation capacity expansion process over a 20-year timeframe, and into an electric power system's daily operation for a single year. Findings from our long-term analysis demonstrated that micro-CHPs helped in reducing cumulative C02 emissions. Under high-to-medium carbon price scenarios, they mostly displaced installed capacity from gas-based technologies, such as natural gas combined cycle units. Other results suggest that a larger micro-CHP penetration could be encouraged through economic incentives such as capital costs reduction, and/or lower natural gas retail prices, where conditions may favor one micro-CHP technology over another. Better economic conditions stimulate the deployment of micro-CHPs with low heat-to-power ratio (HPR), while machines with very high HPR do not appear to be a competitive alternative when compared to other micro-CHP technologies and conventional heating systems. Findings from our short-term analysis demonstrated that widespread deployment of micro-CHPs results in positive effects, such as C02 emissions reductions, energy efficiency improvements, decrease in system energy production costs, and summer peak load reduction at both system and residential levels. It was also found that these benefits could increase with the incorporation of additional features such as a hot water storage unit integrated with the heating system, micro-CHP modulating capability, and a micro-CHP price-based control strategy. However, the benefits at the system level seem to be relatively low for the level of penetration, assumed to be 10% of the total electric installed capacity. Moreover, the operation of a large number of these units considerably increases on-site natural gas fuel consumption all year round. Results also suggest that an adequate tariff design improves the economic efficiency of the system and the operation of micro-CHPs under an intelligent control strategy. When the price signal sent to customers reflects the system's short-term marginal price, the operation of the micro-CHPs is more efficient, and with minimum excess heat. Moreover, findings show that a production subsidy in the form of a buy-back rate impacts the operation of micro-CHPs which may distort the short-term marginal price signal. Depending on the tariff rate, micro-CHPs may favor electricity-only production, resulting in increased costs, increased excess heat, and decreased efficiency. In addition, it was shown that a flat electric tariff rate may result in similar results as with an hourly retail rate, in particular for micro-CHP technologies with medium to high heat-to-power ratio. In the end, the goal of this research is to have a better understanding of the conditions that influence the penetration of micro-CHPs, the economic signals that impact their operation, and the complexities that a widespread penetration brings to energy systems. We observe that this technology lends itself to qualitatively different ways of providing electricity service at value as seen by the customers. Future research is needed to explore potential of micro-CHPs for including customer choice.
by Karen de los Ángeles Tapia-Ahumada.
Ph.D.
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Kirby, Elizabeth Ann. « Quantification of the Impact of Intermittent Renewable Penetration Levels on Power Grid Frequency Performance Using Dynamic Modeling ». ScholarWorks @ UVM, 2015. http://scholarworks.uvm.edu/graddis/519.
Texte intégralRésumé :
As the technology behind renewable energy sources becomes more advanced and cost-effective, these sources have become an ever-increasing portion of the generation portfolios of power systems across the country. While the shift away from non-renewable resources is generally considered beneficial, the fact remains that intermittent renewable sources present special challenges associated with their unique operating characteristics. Because of the high variability of intermittent renewables, the frequency performance of the system to which they are connected can degrade. Generators assigned to regulate frequency, keeping it close to the desired 60 Hz, are forced to ramp up and down quickly in order to offset the rise and fall of the variable resources (in addition to the rise and fall of load), causing transient frequency deviations, power swings, major interface transfer variations and other significant issues.
This research measures the impact of intermittent renewable resource penetration level on power system frequency performance, and offers methods for managing that performance. Currently, the generally accepted amount of regulation (rapidly-dispatchable reserve, used as a supplement to base generation on a short time scale to avoid performance issues) is 1% of peak load. Because of the high variability associated with intermittent renewables, including wind generation (the focus of this thesis), it is expected that this amount of regulation must increase in order to maintain adequate system frequency performance. Thus, the primary objective of this thesis is to quantify the amount of regulation necessary to maintain adequate frequency performance as a function of the penetration level of wind generation.
Presently, balancing resource requirements are computed, in both industry and in the research literature, using static models, which rely entirely on statistical manipulation of net load, failing to capture the intricacies of dynamic system and generator interactions. Using a dynamic model with high temporal resolution data, instead of these statistical models, this thesis confirms the need for additional regulation as wind generation penetration increases. But beyond that, our research demonstrates an exponentially increasing relationship between necessary regulation and wind generation percentage, indicating that, without further technological breakthroughs, there is a practical limit to the amount of wind generation that a typical system can accommodate. Furthermore, we compare our dynamic model results with those of the statistical models, and show that the majority of current statistical models substantially under-predict the necessary amount of regulation to accommodate significant amounts of wind generation. Finally, we verify that the ramping capability of the regulating generators impacts the amount of necessary regulation, although it is generally ignored in current analysis and related literature.
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Mjöberg, Mårten, et Axel Stenfors. « CPTu Configuration Impact on Evaluated Undrained Shear Strength ». Thesis, KTH, Jord- och bergmekanik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-279465.
Texte intégralRésumé :
This thesis evaluates the commonly used geotechnical probing method CPTu, on how different probe configurations impact the resulting evaluated undrained shear strength in soft clay deposits, in comparison to each other and laboratory methods. This is done by performing field investigations on Lindefältet, Södermanlands län, Sweden. Comparison is done on the two Swedish manufacturers of CPTu probes, by different calibration limits, filter types and whether overloading the probe over the calibration limit affects the evaluated undrained shear strength registered. The main conclusions are that one of the manufacturers’ probes registers deviating results in one configuration, that calibration limit has a noticable impact on the results, and that overloading on the probe and filter choice has negliable impact on the results.I detta examensarbete utvärderas den vanligt förekommande geotekniska sonderingsmetoden CPTu, på hur olika konfigurationer av sonder påverkar den resulterande utvärderade odränerade skjuvhållfastheten i lösa leravlagringar, 9i jämförelse med varandra och med laboratoriemetoder. Detta är genomfört genom fältundersökningar på Lindefältet, Södermanlands län. Jämförelsen gjordes på de två svenska CPTu-tillverkarnas sonder. Detta är gjort med hänsyn till olika kalibreringar av konspetstryck, filtertyper, och huruvida sonden har varit överlastad påverkar den utvärderade skjuvhållfastheten som registreras. De huvudsakliga slutsatserna är att en av tillverkarnas sonder registerar udda värden i en konfiguration, att kalibreringar av konspetstryck har en märkbar påverkan på de resulterande värdena på utvärderade odränerade skjuvhållfastheten, samt att överlastning av sonder och val av filtertyp har liten till omärkbar påverkan på resultatet.
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Moiseeva, Ekaterina. « Impact of High levels of Wind Penetration on the Exercise of Market Power in the Multi-Area Systems ». Doctoral thesis, KTH, Elektriska energisystem, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-207090.
Texte intégralRésumé :
New European energy policies have set a goal of a high share of renewable energy in electricity markets. In the presence of high levels of renewable generation, and especially wind, there is more uncertainty in the supply. It is natural, that volatility in energy production induces the volatility in energy prices. This can create incentives for the generators to exercise market power by traditional means: withholding the output by conventional generators, bidding not the true marginal costs, or using locational market power. In addition, a new type of market power has been recently observed: exercise of market power on ramp rate. This dissertation focuses on modeling the exercise of market power in power systems with high penetration of wind power. The models consider a single, or multiple profit-maximizing generators. Flexibility is identified as one of the major issues in wind-integrated power systems. Therefore, part of the research studies the behavior of strategic hydropower producers as main providers of flexibility in systems, where hydropower is available.Developed models are formulated as mathematical and equilibrium problems with equilibrium constraints (MPECs and EPECs). The models are recast as mixed-integer linear programs (MILPs) using discretization. Resulting MILPs can be solved directly by commercially-available MILP solvers, or by applying decomposition. Proposed Modified Benders Decomposition Algorithm (MBDA) significantly improves the computational efficiency.QC 20170516
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Oxenberg, Tanya Palmateer. « The use of catchboxes to minimize the impact to the environment from testing depleted uranium penetrations ». Thesis, Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/18219.
Texte intégral
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Al-Harithi, T. A. « Moroccan policy towards the United States : A study in Moroccan society under the impact of Western penetration 1830-1912 ». Thesis, University of Exeter, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379763.
Texte intégralRésumé :
Morocco's strategic location, its society and its relations with the Mediterranean world all had their impact on relations between Morocco and the United States. After American independence, Morocco was one of the first countries to recognize the United States and as a result had better relations with the latter than any of the other North African countries before 163D. The reward for its friendly attitude was much needed when the French conquered Algeria and Morocco came under the threat of European expansion. During the period between 1830 and 1831,, Morocco's policy towards the United States was based on acquiring American support to fend off the Europeans. After 1871, the Moroccans simply classified the United States in the same category as the European countries. Moroccan policy towards the United States in the period between France's conquest of Algeria and its conquest of Morocco itself was affected by both external and internal affairs in Morocco. It was also guided by the reactions of the United States and the latter's growing interests in Morocco. During that period, three factors dominated Moroccan policy. First, Morocco's desire for American support to prevent further European expansion. Second, Morocco's need to resist American pressure when the United States joined in the European penetration. Third, the Moroccan attitude towards events affecting America such as the American Civil War and the Spanish-American War. The desire for suport was a key element of Moroccan policy during the first four decades following the conquest of Algeria. American reaction, however, was weak because it adhered to its traditional policy: the "Monroe Doctrine". The need to resist American pressure was a result of the United States' growing interests in Morocco. These were manifested in American support for the Jewish issue, its involvement in the system of protection and the arrival of its missionaries in Morocco. These new interests, together with those of the Europeans', damaged Morocco's legal system and economy and resulted in the collapse of Moroccan reforms. The only card left in Morocco's hand was prompted by competition against the European powers over Morocco. When the latter settled their competitions, Morocco lost its independence.
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Makeen, Hafiz Antar Mohammad. « Analysis of anti-cancer drug penetration through multicell layers in vitro : the development and evaluation of an in vitro model for assessing the impact of convective fluid flow on drug penetration through avascular cancer tissues ». Thesis, University of Bradford, 2012. http://hdl.handle.net/10454/5681.
Texte intégralRésumé :
High interstitial fluid pressure (IFP) in tumours is recognized as a barrier to drug delivery resulting in reduced efficacy. High IFP impedes the normal process of convective fluid flow (CFF) from blood vessels into the interstitium. The aim of this study was to develop an in vitro model that could be used to measure CFF and to study its effects on drug delivery. The model consists of a transwell cell culture insert which supports the growth of multicell layers (MCL) on collagen coated membranes. A graduated tube is inserted into the transwell and a pressure gradient is applied across the membrane by raising the volume of medium in the tube above that of the bottom chamber. CFF is determined by measuring the weight of medium in the bottom chamber as a function of time. CFF was inversely proportional to MCL thickness and 41.1±3.6µm thick MCL has completely stopped CFF. Using a physiologically relevant hydrostatic pressure of 28mmHg, a CFF of 21µL/min was recorded using a DLD-1 MCL that was 12.21±3.2µm thick. Under these conditions, the rates of penetration of doxorubicin, imatinib and gefitinib were respectively 42, 26 and 13 folds greater than when no CFF exists. Reversing the CFF so that it opposed the drug diffusion gradient significantly impairs drug penetration. In conclusion, a novel in vitro model for assessing the impact of CFF on drug delivery has been developed. This model could be used to evaluate strategies designed to increase drug delivery to solid tumours by modifying the CFF.
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Wang, Wei. « Simulation of hard projectile impact on friction stir welded plate ». Thesis, Cranfield University, 2011. http://dspace.lib.cranfield.ac.uk/handle/1826/7213.
Texte intégralRésumé :
A numerical simulation is conducted using LS-DYNA to simulate hard projectile impact on a friction stir welded (FSW) plate. As the hard projectile has a wide range of velocity, mass and shape, when referring to AMC 25.963(e) of CS-25, ―Fuel Tank Access Cover‖, the hard projectile can be defined as 9.5 mm cubic-shaped steel engine debris with an initial impact velocity of 213.4 m/s (700 ft/s). This preliminary study was to evaluate whether the fuel tank adjacent skin panel joined by FSW would pass the regulation. First, the geometry and Johnson-Cook material model of the FSW joint were developed based on previous experimental research and validated by comparison with the tensile test on the FSW specimen. Then the impact on an Aluminium Alloy 2024 (AA 2024) plate without FSW was modelled. The minimum thickness of a homogeneous AA 2024 plate which could withstand the impact from engine debris is 3 mm. Finally the impact on 3 mm thick AA 2024 FSW plate was simulated. The welding induced residual stress was implemented in the plate model. The impact centre was changed from the nugget zone to the thermo-mechanically affected zone, heat-affected zone and base material zone of the FSW joint. Penetration only occurred in the model with impact centre on the nugget zone. Additional simulation indicated that increasing the thickness of the FSW plate to 3.6 mm could prevent the penetration.
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Gautam, Himanshu. « The Impact of Customer Battery Storage on the Smart Grids and how Power Tariffs can increase Battery Storages’ penetration percentage ». Thesis, KTH, Elektroteknisk teori och konstruktion, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-217829.
Texte intégralRésumé :
The batterystoragewillplayanimportantroleinfuturesmartdistributiongrids.Atthesame time,thereshouldbeavailabilityofvaryingtariffstructures,fromwhichcustomerscan chooseaccordingtotheirrequirement.Thisresearchthesisfocusesonthestudyofimpact ofbatterystorageinthedistributiongridandhowpowertariffscanhelpincreasethebattery storage’spenetrationpercentage.The researchisdonetoassesstheimpactofbothhomebatteriesandEVsonthedistributiongrid, andhowmuchcantheyincreaseordecreasethedemandintheregion.Alsoapartofthesis isdedicatedtocreatenewpowertariffstructuresforStockholmregionofEllevio,andthenelectricity billsoftheconsumersarecomparedwithexistingtariffsandnewsuggestedtariffs.ForthethesisaresidentialareaofStockholmRoyalSeaport/NorraDjurgårdenstadenischosen.Ellevio iselectricitydistributionresponsibleforthearea.HomebatteriesofPowervaultU.KandTeslaPowerwall2arechosenandforEV,TeslaModelSwith60KWhbatterysizeisselected.One ofthemostinterestingfindingsisthatagroupof480customerswithhomebatterycanbring thepowerdemandduringpeakhoursdownbyupto11%,butontheotherhanda50%penetration ofEVintheareacanincreasedemandatcertainhoursbymorethan250%.Oneofother findingwasthatifcustomersshifttheirchargingpatternofEVbycoupleofhourstheycan increasethedemandinthegrid,emphasizingontheroleofcustomersinfuturedistributionsystems.SuggestedPowertariffsshowanincreaseinmonetaryamountsavedbycustomerifthey optforhomebatteries.Themostamountsavedbythecustomerisincaseofthestrictestpower tariffsuggested,i.e.Powertariffwithcriticaltimecomponentandtimeofusecomponent.This thesiswillbecomeafoundationforfuturestudyofimpactofbatteriesonalargerregionand impactofbatteriesownedbyDSOinthegrid.Italsoopensnewpathwaystostudyvaryingretail contractsforthecustomersandhowcombinationofvaryingretailcontractandpowertariffs canresultinbetterdemandflexibility.Batterilager kommerattspelaenviktigrolliframtidasmartaeldistributionsnät.Sam-tidigt bördetfinnasmöjlighettillvarierandeeltariffstrukturerförelkonsumenter.Dettaexamensarbete fokuserarpåstudieraveffektenavbatterilagringieldistributionsnätetochhureltarifferkanbidratillattökagenomslagetavbatterilager.Studierharävengjortsföratt bedömaeffektenpåeldistributionsnätetavhembatterierochelfordonmedstudieravhurefterfrågan påelinverkas.Specifiktföreslåsnyaeltarifferförettområdedärelräkningarförelkunder jämförsmedexisterandeochföreslagnanyaeltariffer.Arbetet harutförtsisamarbetemellanEllevio,denlokalaeldistributöreniStockholm,ochKTH. FallstudierharutförtsförbostadsområdetNorraDjurgårdsstaden.Vidarehartvåolikatyper avhembatteriervaltsförstudienvilkaärPowervaultrespektiveTeslaPowerwall2.Förstudie avelfordonharTeslaModelSvaltsmed60kWhbatteristorlek.Resultat frånfallstudiernavisarattengruppom480hushållskundermedhembatteri,kanminska totalaefterfråganpåelvidtopplastmedupptill11%.Resultatenvisarattom50%avpersonbilsparkenisammaområdevarelfordonskulleefterfråganavelvidtopplastökamed merän250%.Studiernavisarhurolikaladdningsmönsterförelbilarinverkarpåtotalabelastningen ielnätet.Därmedgesexempelpådencentralarollenelkonsumentenfåridetframtida eldistributionsnätet.Föreslagnaenergitarrifferförelvisarpåmöjlighetentillekonomiskvinst förelkonsumentervilkaanvänderhembatterier.Arbetet liggertillgrundförframtidastudieravinverkanavbatterieristörreområdenochbatteriersomägsaveldistributören.Ettannatområdeförframtidastudierärhurelkon-sumenternas efterfrågeflexibilitetkanökaserhållasgenomvarierandelösningarförelavtalochenergitariffer.
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朱紫瓊 et Chi-king Chu. « The penetration of Japanese capital in the commercial property market in Hong Kong and its possible impact on urban design ». Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1990. http://hub.hku.hk/bib/B31979701.
Texte intégral
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DE, LEON RAFAEL. « Modeling the impact of variable renewable energy sources penetration on supply-demand balance : Analysis of France from 2021 to 2025 ». Thesis, KTH, Skolan för industriell teknik och management (ITM), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-294583.
Texte intégralRésumé :
France is planning a strong development of solar photovoltaics (PV) and wind power in the medium term disrupting the power system. This Master Thesis analyzes the impacts of variable renewable energy production on the supply-demand balance from 2021 to 2025 in France. The model used relies on a dynamic programming method. The analysis is based on the assessment of indicators such as price signals, margins, loss of load duration (LOLD), expected energy not served (EENS) and nuclear drop stop that characterize the supply-demand balance and the security of supply of the electricity system. Wind power and PV are two very different technologies. Their load factor is very sizeable as it characterize their seasonality, variability and predictability and has an impact on all medium-term indicators. Wind power and PV have low marginal costs and their production is seasonal and in anti-phase. With new installed capacity, their added production in the supply-demand balance will substitute first the imports from the interconnections until saturation and then nuclear and thermal power plant production. Prices decrease with the same seasonality as the production and need to be considered when establishing the nuclear planning for the years to come. In addition a re-optimization of hydro power is observed. In terms of security of supply, wind power is more efficient than PV when assessing the reduction of LOLD but both are far from the performance of combined cycle gas turbines (CCGT). Lastly, the lack of nuclear production opportunities increases considerably more with PV due to a very localised production during the day which coincides in summer with periods of low consumption. Wind power and PV are two distinct technologies and should not be put in the same category when assessing their impact on the power system.Frankrike planerar en stark utveckling av solceller (PV) och vindkraft på medellång sikt för att störa kraftsystemet. Detta examensarbete analyserar effekterna av varierande produktion av förnybar energi på balans mellan utbud och efterfrågan från 2021 till 2025 i Frankrike. Modellen som används bygger på en dynamisk programmeringsmetod. Analysen baseras på bedömningen av indikatorer som prissignaler, marginaler, förlust av lasttid (LOLD), förväntad energi som inte serveras (EENS) och kärnkraftsfallstopp som kännetecknar efterfrågan och utbudssäkerheten för el systemet. Vindkraft och solceller är två mycket olika tekniker. Deras belastningsfaktor är mycket stor eftersom den kännetecknar deras säsongsvariation, variation och förutsägbarhet och påverkar alla medellångsiktiga indikatorer. Vindkraft och solceller har låga marginalkostnader och deras produktion är säsongsbetonad och i fas. Med ny installerad kapacitet kommer deras extra produktion i utbuds- och efterfrågan att ersätta importen från sammankopplingarna till mättnad och sedan produktion av kärnkraft och värmekraftverk. Priserna sjunker med samma säsong som produktionen och måste beaktas när kärnkraftsplaneringen fastställs för de kommande åren. Dessutom observeras en återoptimering av vattenkraften. När det gäller försörjningstrygghet är vindkraft effektivare än solceller vid bedömning av minskningen av LOLD men båda är långt ifrån prestanda för kombinerade cykelturbiner (CCGT). Slutligen ökar avsaknaden av kärnkraftsproduktionsmöjligheter betydligt mer med solceller på grund av en mycket lokal produktion under dagen som sammanfaller på sommaren med perioder med låg konsumtion. Vindkraft och solceller är två olika tekniker och bör inte placeras i samma kategori när man bedömer deras inverkan på kraftsystemet.
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Chu, Chi-king. « The penetration of Japanese capital in the commercial property market in Hong Kong and its possible impact on urban design ». Hong Kong : University of Hong Kong, 1990. http://sunzi.lib.hku.hk/hkuto/record.jsp?B25796604.
Texte intégral
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Cakir, Tanju. « Resistance Of Alumina Ceramics To Kinetic Energy Projectiles ». Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/4/1260450/index.pdf.
Texte intégralRésumé :
The objective of this study is to investigate the penetration and perforation resistance of alumina ceramics against kinetic energy projectiles. There are several different mechanisms by which a target can fail when it is subjected to impact of a projectile and these may occur singly or in combinations of two or more. The presence of large number of penetration and failure mechanisms makes the investigation of the perforation very difficult. Because of this difficulty, the analytical investigations of penetration and perforation processes usually assume one type of failure mechanism. One of these analytical investigations is reviewed and it is seen that this analytical model is capable of predicting after impact parameters reasonably accurately. A parallel investigation of this problem is also been carried out numerically by using
Autodyn hydrocodes. Numerical study is capable of simulating the main changes in ceramic/steel composite target during penetration process of kinetic energy projectile. Results of analytical and numerical investigations are parallel to each other. A set of experiments was carried out for checking the results of analytical and numerical calculations with the experimental data.
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Al, Buflasa Hanan Mubarak. « Impact of high wind power penetration into power systems with reverse osmosis desalination plants, taking Kingdom of Bahrain as a case study ». Thesis, Loughborough University, 2008. https://dspace.lboro.ac.uk/2134/36131.
Texte intégralRésumé :
This study is based on the Bahraini government's interest in the construction of largescale renewable energy projects in Bahrain. This thesis investigates the impact of integrating a high penetration of wind power into Bahrain's power system. It includes wind and site assessment and a study of the correlation between wind power and power demand. The power system is analysed before and after wind integration covering different wind penetration levels. In order to mitigate against the possible impact of high levels of wind power, the operation of reverse osmosis stations is modelled as a means of providing additional grid balancing. The geographical distribution of wind speed (the wind atlas) for the kingdom of Bahrain is presented, based on measured data and on calculations undertaken using WAsp and Matlab. The data used were recorded by the Meteorological Directorate using a weather station at Bahrain International Airport. The data were taken on an hourly basis for a period of ten years. These data indicate an annual mean wind speed of 6.93 m/s at 60 m height and mean Weibull scale and shape parameters C and k of 7.80 m/s and 1.79 respectively. This suggests that the area has a good wind resource. The wind atlas shows that several locations in the less populated central and southern regions of the main island of the archipelago of Bahrain are potentially suitable for wind energy production.
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Cramphorn, E. A. « The viability of image registration as a method for the quantification of displacement in penetrating impact experiments ». Thesis, University of Sheffield, 2018. http://etheses.whiterose.ac.uk/21942/.
Texte intégralRésumé :
Experimental characterisation of tissue deformations associated with penetrating impact of fragments from explosive devices is challenging. Whereas experiments involving ballistic gelatine tissue simulants enable direct visualisation of deformation patterns, quantification of these deformations remains difficult. This thesis investigates the use of image registration for this purpose. Image registration methods optimise alignment of corresponding structures in image pairs, and in the process estimate the deformation fields that best achieve this. In the current context, it is hypothesised that registration of consecutive images from videos of gelatine penetration events can enable the corresponding gelatine deformation fields to be estimated. Three main activities were undertaken towards validation of this hypothesis: the proposed registration approach was tested on a series of synthetic images emulating the types of deformations expected in penetration events; the approach was then tested on images derived from a carefully controlled indentation experiment, in which a block of gelatine was deformed quasi-statically with a rigid indenter while the resulting deformation was filmed; and finally it was tested on video footage from projectile penetration experiments, in which metal projectiles were fired into blocks of gelatine and filmed with a high speed video camera. A series of complementary studies was also undertaken in support of these experiments. Firstly, to better understand the parameters of real penetration scenarios, the fragment generation and flight behaviour of a typical explosive device were analysed. Secondly, to improve understanding of the material behaviour of the test gelatine, mechanical characterisation tests were undertaken, and a visco-hyperelastic constitutive model was proposed. The individual registration operations themselves appeared to perform well, in the sense that initially disparate consecutive image pairs were brought into good alignment. However, composition of the corresponding transformation fields, necessary for tracking accumulated deformations over the course of a video sequence, was found to yield artefacts and unphysical deformation estimates in some cases. These were judged to result both from deficiencies in the methods themselves, and flaws in the experimental arrangements. Therefore, while the proposed registration approach appears to show promise, further work is needed to establish its validity conclusively. The thesis closes with a discussion of possible approaches to the latter.
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PIRIU, ANDREEA ALEXANDRA. « ESSAYS ON GLOBALISATION : EFFECTS AND IMPLICATIONS FOR INDIVIDUALS ». Doctoral thesis, Università degli Studi di Milano, 2020. http://hdl.handle.net/2434/728739.
Texte intégralRésumé :
This thesis studies the effects of import competition from China and Eastern Europe
on the health and fertility decisions of German individuals working in manufacturing.
Individuals are matched with separate measures of exposure to competition from China
and Eastern Europe, respectively. To isolate exogenous supply shocks from the origin,
instrumental variables for competition from each of China and Eastern Europe are constructed.
Results in Chapter 1 suggest that higher import competition worsens individual health via
job displacement, wage decline, shortened employment duration, increased reliance on
welfare and less future orientation, with Chinese import competition affecting individuals
twice as much. Health declines as individuals increase their visits to the doctor, exercise
less frequently and have a higher probability of developing chronic illness. Also, there is
some evidence that individuals do not tend to become disabled but may be slowly pushed
into chronic illness.
Findings in Chapter 2 show that import competition negatively affects the individual’s
probability of having children via reduced earnings, lower satisfaction with personal
income and shortened employment duration. The chapter then investigates effects of
import exposure by gender. Results show that male and female fertility choices differ
upon rising import competition. Higher import exposure lowers female earnings and
job autonomy, which in turn generates a lower opportunity cost of work, to the point
where having children would become a more rewarding alternative for female workers.
By contrast, increased import exposure negatively affects male workers’ fertility through
reduced earnings and employment duration.
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Engelbrecht, Tanja Nadine [Verfasser], R. [Akademischer Betreuer] Neubert, B. [Akademischer Betreuer] Dobner et G. [Akademischer Betreuer] Brezesinski. « Impact of ceramides and penetration enhancers on the nanostructure of Stratum corneum lipid model membranes / Tanja Nadine Engelbrecht. Betreuer : R. Neubert ; B. Dobner ; G. Brezesinski ». Halle, Saale : Universitäts- und Landesbibliothek Sachsen-Anhalt, 2012. http://d-nb.info/1025352920/34.
Texte intégral
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Mohamed, Ali Mohamed. « ANALYZING THE IMPACT OF PHOTOVOLTAIC AND BATTERIE SYSTEMS ON THE LIFE OF A DISTRIBUTION TRANSFORMER ». Thesis, Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-54952.
Texte intégralRésumé :
This degree project presents a study case in Eskilstuna-Sweden, regarding the effect of the photovoltaic (PV) systems with battery energy storage system (BESS) on a power distribution transformer, and how they could change the transformer lifespan. For that, an extensive literature review has been conducted, and two MATLAB models were used to simulate the system. One model simulates the PV generation profile, with the option of including battery in the system, and the other one simulates the transformer loss of life (LOL) based on the thermal characteristics. Simulations were using hourly time steps over a year with provided load profile based on utility data and typical meteorological year weather data from SMHI and STRÅNG. In this study, three different scenarios have been put into consideration to study the change of LOL. The first scenario applies various levels of PV penetrations without energy storage, while, the other scenarios include energy storage under different operating strategies, self-consumption, and peak shaving. Similarly, different battery capacities have been applied for the purpose of studying the LOL change. Thus, under different PV penetrations and battery capacities, results included the variation of LOL, grid power, battery energy status, and battery power. Moreover, results concluded that the PV system has the maximum impact on LOL variation, as it could decrease it by 33.4 %, and this percentage could increase by applying different battery capacities to the system. Finally, LOL corresponding to the battery under peak shaving strategy varies according to the battery discharge target. As different peak shaving targets were used to control the battery discharge, and hence, study the impact on the transformer and estimate its LOL.
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Sucre, Eric Brandon. « Soil resource heterogeneity and site quality in Southern Appalachian hardwood forests : Impact of decomposing stumps, geology and salamander abundance ». Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/29470.
Texte intégralRésumé :
The Southern Appalachian hardwood forests contain a wide diversity of flora and fauna. Understanding processes that affect nutrient availability in these forests is essential for sound forest management. Three interconnected research projects regarding soil resource heterogeneity were designed to increase our understanding of this ecosystem. The objective of these projects were as follows: 1) to examine and quantify the role of decaying stumps in regards to total carbon (C) and nitrogen (N) pools and fine-root dynamics, 2) compare and contrast the use of ground-penetrating radar (GPR) vs. a soil auger for estimating soil depth and site quality and 3) to evaluate how eastern red-backed salamanders (Plethodon cinereus) affect N-availability.
For the stump study, results show that decomposing stumps occupy approximately 1.2% of the total soil volume and constitute 4% and 10% of total soil N and C pools. Significant differences in N (p = 0.0114), C (p = 0.0172), microbial biomass C (p = 0.0004), potentially mineralizable N (p = 0.0042), and extractable NH4+ (p = 0.0312) concentrations were observed when compared to mineral soil horizons. In particular, potentially mineralizable N was 2.5 times greater in stump soil than the A-horizon (103 vs. 39 mg kg-1), 2.7 times greater for extractable NH4+ (16 vs. 6 mg kg-1) and almost 4 times greater for MBC (1528 vs. 397 mg kg-1). These measured properties suggest higher N-availability, organic matter turnover and N uptake in stump soil versus the bulk soil. 19% of the total fine root length and 14% of fine root surface area also occurred in the stump soil. The increased fine root length suggests higher concentrations of labile nutrient in the stumps since roots often proliferate in areas with higher nutrient availability. Significant differences occurred in N and C concentrations between all four decay classes and the A-horizon, which validated the use of this system and the need to calculate weighted averages based on the frequency and soil volume influenced by each decay class.
In the GPR Study, depth estimations were shallower using a soil auger compared to estimates obtained using GPR across all plots (p = 0.0002; Figure 3.4). On a soil volume basis, this was equivalent to about 3500 m3 of soil per hectare unaccounted for using traditional methods. In regards to using soil depth as a predictor for site quality, no significant relationships were observed with soil depth estimations obtained from the auger (Table 3.3). On the other hand, depth measurements from GPR explained significant amounts of variation across all sites and by physiographic region. Across all sites, soil depth estimates from GPR explained 45.5% of the residual variation (p = 0.001; Table 3.3). When the data were stratified by physiographic region, a higher amount of variation was explained by the regression equations; 85% for the Cumberland Plateau (p = 0.009), 86.7% for the Allegheny Plateau (0.007) and 66.7% for the Ridge and Valley (p = 0.013), respectively (Table 4.2). Results from this study demonstrate how inaccurate current methods can be for estimating soil depth rocky forests soils. Furthermore, depth estimations from GPR can be used to increase the accuracy of site quality in the southern Appalachians.
In the salamander study, no significant salamander density treatment or treatment by time effects were observed over the entire study period (p < 0.05). However, when the data were separated by individual sampling periods a few significant treatment by time interactions occurred: 1) during August 2006 for available NH4+ under the forest floor (i.e. horizontal cation membranes; p = 0.001), 2) August and 3) September 2006 for available NH4+ in the A-horizon (p = 0.026), and 4) May 2007 for available NO3- under the forest floor (p = 0.011). As a result of these trends, an index of cumulative N-availability (i.e. NH4+ and NO3-) under the forest floor and in the A-horizon was examined through the entire study period. Cumulative N-availability under the forest floor was consistently higher in the low- and medium-density salamander treatments compared to the high-density treatment. For cumulative N-availability in the A-horizon, a gradient of high to low N-availability existed as salamander density increased. Factors such as a prolonged drought in 2007 may have affected our ability to accurately assess the effects of salamanders on N-availability. We concluded that higher salamander densities do not increase N-availability.
Implementing methodologies that accurately account for soil nutrient pools such as stump soil, physical properties such as depth and fauna such as salamanders, increase our understanding of factors that regulate site productivity in these ecosystems. As a result, landscape-level and stand-level management decisions can be conducted more effectively.Ph. D.
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Taddei, Lorenzo. « Simulation numérique en dynamique rapide à l’aide de la méthode SPH (Smoothed Particle Hydrodynamics). : Application à la biomécanique de l’impact ». Thesis, Bourgogne Franche-Comté, 2017. http://www.theses.fr/2017UBFCA017.
Texte intégralRésumé :
Dans le cadre de la simulation numérique portant sur la prédiction de phénomènes complexes, la modélisation de la pénétration d’un corps à travers un solide reste un challenge. Ceci est d’autant plus vrai si le corps impacté comporte une épaisseur importante devant les dimensions du projectile. Notamment, dans le contexte de la biomécanique des chocs, l’investigation des traumatismes suite à une blessure par balle, par un moyen numérique, nécessite la modélisation d’une zone pouvant être de plusieurs dizaines de fois supérieure aux dimensions du projectile sur un temps extrêmement court (de l’ordre de quelques dixièmes de milli-seconde). Les méthodes numériques dites classiques comme les éléments finis sont limitées dans ce domaine, dû en particulier à des problèmes de distorsions de maillage. Ce travail de thèse tente donc d’apporter une contribution dans le cadre de la modélisation des impacts pénétrants en proposant l'utilisation d’une méthode alternative sans maillage, la méthode "Smoothed Particle Hydrodynamics" (SPH).Méthode "Smoothed Particle Hydrodynamics, Impact Pénétrant, Biomécanique, Dynamique Rapide, AxisymétrieNumerical simulation offers the possibility to investigate complexe phenomenons by giving access to useful informations about the evolution of a material system under constraints. Nevertheless, there are some situations where classical procedures, such as the Finite Elements Method (FEM), suffers from issues (e.g. mesh distorsions). One of these situations comes from a biomechanical context, where the investigation tends to observe the penetration of a projectile through human soft tissus. In this context, the objective of this Ph.D Thesis is to evaluate the capability of one alternative method, named Smoothed Particle Hydrodynamics method (SPH), to handle such modelling configurations.Smoothed Particle Hydrodynamics method, Penetrating Impact, Biomechanics, Fast Dynamics, Axis-symmetry
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ZHOU, XIAO-WEI. « Contribution au comportement dynamique des materiaux metalliques : etude experimentale de l'alliage al-li en torsion et en compression, simulation numerique du processus de penetration a grande vitesse ». Nantes, 1988. http://www.theses.fr/1988NANT2014.
Texte intégralRésumé :
Etude experimentale sur les alliages al-li soumis a des essais de traction et de compression pour des vitesses de deformation comprises entre 10**(-4) et 310**(3) s**(-1) et de 10**(-3) a 210**(3) s**(-1) respectivement. Auparavant ces alliages ont ete traites thermiquement. Analyse de la sensibilite a la vitesse de deformation. Influence du mecanisme d'activation thermique sur le processus de deformation. Determination du mode de rupture. Analyse des facies de rupture pour les echantillons deformes en traction et de la formation des cellules de dislocation dans ceux deformes en compression. Simulation numerique du processus de penetration a grande vitesse d'une cible mince par un projectile circulaire en utilisant un modele de fluide elasto-plastique. Comparaison avec des resultats experimentaux
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Ettinger, Susanne. « Geomorphological impact of lahars on the southwestern flank of Cotopaxi volcano, Ecuador : drainage system and alluvial fan ». Thesis, Clermont-Ferrand 2, 2012. http://www.theses.fr/2012CLF20017.
Texte intégralRésumé :
Pendant une éruption volcanique sur des sommets englacés, des coulées de débris syn-eruptifs,dénommées lahars, peuvent être générées par la fonte partiale de glaciers. Ce phénomène estbien connu sur le volcan Cotopaxi, Equateur. La présente étude concerne trois vallées et un cônede déjection sur le flanc sud-ouest de ce volcan. Une première analyse a été conduite par relevésde formes géomorphologiques dans ces vallées qui témoignent des processus d’érosion et desédimentation lors du passage de lahars dans le passé, notamment ceux du dernier événementéruptif datant de 1877 AD. Bien que les types des formes géomorphologiques déterminées sontles mêmes, leur distribution spatiale varie d’une vallée à l’autre en fonction d’une interaction deparamètres morphologiques locaux. Les conditions environnementales individuelles déterminentégalement le volume de l’écoulement, paramètre crucial dans la délimitation de zones de risques delahars dans les plaines adjacentes. Pour cela, une deuxième étude a été menée à grande échelle surle cône de déjection à l’exutoire de la vallée la plus au Sud des trois. Une analyse intégrale de la morphologiede surface et des affleurements naturels a été complétée par des données stratigraphiquesde subsurface obtenues via un sondage avec un Géoradar. Reconstituer l’architecture sédimentairede ce cône permet de visualiser la distribution spatiale de formes érosives et de dépôts. L’étude àrévélé que différentes parties du cône sont actives à des moments distincts et les épaisseurs dedépôts de lahars sont variables en fonction du type d’écoulement et de son volume. Ceci permetde relier les dynamiques géomorphologiques des plaines alluviales aux zones d’initiation de laharssur les flancs du volcan. Enfin, cette étude a débouché sur la mise en place d’une nouvelle fonctiondans le logiciel de modélisation de lahars LAHARZ prenant en compte l’incorporation progressive desédiment dans un contexte érosif dans les vallées, ce qui permet une meilleure délimitation de zonesde risque de lahars sur le côneDuring a volcanic eruption at ice capped volcanoes, syn-eruptive volcanic debris flows, lahars, canbe triggered through the partial melting of the glaciers. This phenomenon is well known to have happenedat Cotopaxi volcano, Ecuador, where the present study has been realized. The latter concernsthree drainages on the southwestern flank of the volcano and one alluvial fan. A first analysis hasbeen conducted assessing geomorphologic features in the drainages testifying from erosional anddepositional processes during past lahars, in particular of those generated during the last eruptiveevent dating back to 1877 AD. Although the types of determined geomorphologic features are thesame, their spatial distribution varies among the three valleys as a function of an interplay of localmorphologic parameters. The individual environmental conditions determine also the flow volumeof such lahars, a critical parameter when to delineating hazard zones in the adjacent lowlands. Thesecond analysis has therefore be performed at large scale on the alluvial fan forming at the mouthof the southernmost of the three drainages. An integral study of the surface morphology and naturalexposures was enriched with subsurface stratigraphic information obtained through a ground penetratingradar survey. The sediment architecture of the fan provides valuable insights on the distributionof erosional features and deposits. Different fan parts appear to be active at different times andlahar deposit thicknesses are highly variable as a function of flow type and volume. This allows torelate floodplain dynamics to the initiation zone of lahars on the upper flanks of the volcano. At last,this research led to integrate a new bulking function acknowledging for erosional processes in thevalleys into the lahar-modeling software LAHARZ allowing to better delineate lahar hazard zones onthe fan