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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
321

Improved Energy Modelling of Wireless Personal Area Network

Wahab, Junaid, Ali, Zubair January 2009 (has links)
<p>Wireless sensors networks are used in a variety of environments ranging from environment</p><p>monitoring such as humidity and temperature, to environments like patient monitoring, habitat</p><p>monitoring etc. Sometimes sensors are deployed in inaccessible or hazardous places, and they</p><p>are battery operated; recharging or changing the sensor’s battery is almost impossible.</p><p>In such scenarios, where the battery can not be recharged or changed, it is crucial to know in</p><p>advance how long the battery will last so that the old sensor node can be replaced by a new</p><p>one. Normally, in order to effectively utilize the battery the components of a wireless sensor</p><p>node are turned off when not needed.</p><p>This paper presents an in-depth analysis of the importance of switching sensor node</p><p>components, and its impact on the life time prediction. A new energy model is presented</p><p>which caters for the current and time consumed in switching from one mode to another. A</p><p>comparison is made between scenarios where current consumption while switching is catered</p><p>with the one where it is not catered. This was achieved by using on chip fuel gauge, with</p><p>some limitation, which was verified by using digital multimeter.</p>
322

Effects of Different Silvicultural Treatments on the Distribution of Light in Upland Hardwood Forest Stands of the Cumberland Plateau.

Grayson, Stephen Frederick 01 December 2010 (has links)
Although manipulation of the light regime is a common goal of silvicultural treatments, the specific light conditions created are poorly documented for many forest types and geographic locations. To help quantify effects of silivicultural treatments on light conditions, basal area, canopy structure, and photosynthetically active radiation (PAR), collected both instantaneously and across time, were measured in central hardwood forests following silvicultural treatments. These measurements were used to: 1.) investigate the magnitudes of differences in understory percent ambient PAR following implementation of shelterwood and thinning treatments; 2.) document the specific amount and variability of understory percent ambient PAR in shelterwood treatments (mean residual basal area=21 ft2/ac [4.8 m2/ha]), thinning (78 ft2/ac [17.9 m2/ha]), and untreated controls (18 ft2/ac[4.1 m2/ha); and 3.) Examine relationships between: basal area and canopy cover; basal area and measured percent ambient PAR; and canopy cover and measured percent ambient PAR. It was found that greater light levels resulted from greater canopy removals. Indexes of variability in light across time and among locations within a stand were higher in the shelterwood and thinning treatments than in the uncut control. Simple linear regression relationships were observed between basal area and PAR (r2= 0.8784 for instantaneous measurements, r2= 0.9697 for continuous measurements), and basal area and canopy cover (r2=0.8479). Such relationships provide a means for including light management in forest planning and application of silivicultural treatments.
323

Multi-area power system state estimation utilizing boundary measurements and phasor measurement units ( PMUs)

Freeman, Matthew A 30 October 2006 (has links)
The objective of this thesis is to prove the validity of a multi-area state estimator and investigate the advantages it provides over a serial state estimator. This is done utilizing the IEEE 118 Bus Test System as a sample system. This thesis investigates the benefits that stem from utilizing a multi-area state estimator instead of a serial state estimator. These benefits are largely in the form of increased accuracy and decreased processing time. First, the theory behind power system state estimation is explained for a simple serial estimator. Then the thesis shows how conventional measurements and newer, more accurate PMU measurements work within the framework of weighted least squares estimation. Next, the multi-area state estimator is examined closely and the additional measurements provided by PMUs are used to increase accuracy and computational efficiency. Finally, the multi-area state estimator is tested for accuracy, its ability to detect bad data, and computation time.
324

The significance of organic carbon and sediment surface area to the benthic biogeochemistry of the slope and deep water environments of the northern Gulf of Mexico

Beazley, Melanie J. 30 September 2004 (has links)
The bioavailability of metabolizable organic matter within marine sediments is one of the more important driving mechanisms controlling benthic pelagic communities. Interactions between organic material and mineral surfaces within the sediment, such as adsorption, can cause organic matter to be unavailable for degradation by organisms; therefore for this study we have used the relationship of organic carbon-to-sediment surface area as an indicator of available organic carbon in northern Gulf of Mexico sediments. We have determined that these sediment interactions demonstrate a significant association with benthic fauna abundances; however they are not the most dominant environmental variables. It may be the combination of biogeochemical parameters, such as organic carbon content, sediment surface area, grain size, water depth and other geophysical variables, that is the ultimate control on the bioavailability of metabolizable organic matter in the northern Gulf of Mexico.
325

Etude de l'expression du gène EphA7 et de son ligand ephrine-A5 dans le cortex en développement/ Transcriptional regulation of EphA7 and ephrin-A5 gene in the developing forebrain

Pietri, Sandra 26 October 2010 (has links)
Le cortex cérébral constitue l’une des structures les plus évoluées et complexes de notre cerveau. Sa surface est divisée en de nombreuses aires fonctionnelles. La mise en place des aires corticales dépend à la fois de facteurs intrinsèques comme la sécrétion de morphogènes ou l’expression en gradient de différents facteurs de transcription, mais elle dépend aussi de facteurs extrinsèques au cortex, en particulier l'innervation par le thalamus. Les ephrines et leurs récepteurs Eph constituent une famille multigénique de facteurs de signalisation impliqués dans divers événements clé du développement cortical où ils sont exprimés selon des profils spatio-temporels complexes. Aux stades tardifs du développement, EphA7 et l’ephrine-A5 sont exprimés en gradients complémentaires au sein de chaque territoire des aires présomptives, constituant ainsi les marqueurs les plus précoces de ces aires corticales. Par la combinaison d’approches in-vitro utilisant la technique d’électroporation focale de tranches corticales embryonnaires, puis in-vivo en utilisant la technique de transgénèse d’addition, nous avons identifié une séquence régulatrice de EphA7 appelée pA7, capable de mimer l’expression endogène de EphA7 au sein du télencéphale dorsal en développement. La lignée de souris pA7-GFP ainsi générée exprime la GFP spécifiquement au sein du télencéphale dorsal durant les stades précoces. Aux stades périnataux cette expression se régionalise au sein de la plaque corticale de chacune des aires présomptives selon des gradients récapitulant ceux observés pour EphA7. Nous avons ensuite purifié des neurones exprimant différents niveaux d’EphA7 par la technique de FACS «Fluorescence-Activated Cell Sorting » et l’analyse de leur transcriptome nous a permis de trouver un grand nombre de gènes différentiellement exprimés. Tous ceux testés par la technique d’hybridation in situ sont exprimés selon un gradient latéral fort et médial faible dans le cortex pariétal, similaire à celui d’EphA7. L’examination de leur profil au sein de cortex de souris dépourvus d’afférences thalamiques, nous a permis de conclure que l’expression de ces gènes incluant EphA7 s’établit indépendamment de celles-ci. Ainsi, notre étude a permis d'identifier un répertoire de gènes neuronaux, pouvant agir en amont ou en combinaison avec EphA7 pour contrôler les facteurs intrinsèques essentiels à l’établissement des aires corticales./ The cerebral cortex is subdivided into distinct cortical areas characterized by specific patterns of gene expression and neuronal connectivity. The patterning of cortical areas is thought to be controlled by a combination of intrinsic factors that are expressed in the cortex, and external signals such as inputs from the thalamus. EphA7 is a member of the ephrin/Eph family of guidance factors that is involved in key aspects of the development of the cortex, and is expressed in several gradients within developing cortical areas. By combining in vitro transcriptional assays and mouse transgenics, we identified a regulatory element of the EphA7 promoter, named pA7, that can recapitulate salient features of the pattern of expression of EphA7 in the developing forebrain, including gradients in the cortex. Using a mouse reporter line where GFP expression recapitulates EphA7 expression, we developed a GFP-based cell sorting procedure to isolate cortical neuron populations displaying different levels of EphA7 expression. Transcriptome analysis of these populations enabled to identify a specific array of differentially expressed genes. All genes validated further in vivo were confirmed to be expressed along distinct gradients in the developing cortical plate, similarly to EphA7. The expression of these genes was unchanged in mutant mice defective for thalamocortical projections, indicating that their graded pattern is largely intrinsic to the cortex. Our study identifies a novel repertoire of cortical neuron genes that may act upstream of, or together with EphA7, to control the intrinsic patterning of cortical areas.
326

Was sind und zu welchem Ende betreiben wir Regionalwissenschaften? : Eine politikwissenschaftliche Perspektive

Mols, Manfred January 2002 (has links)
On the occasion of his farewell lecture, Manfred Mols looks back to his academic work of the last four decades, and discusses the essential meaning of area studies.<br> He tries to clarify the important denotation of institutes for regional researchers. Area studies should help us to understand changing processes in international policies and they do. He underlines his critical point of view with the position and treatment of area studies among certain universities in Germany.
327

FPGA based reconfigurable body area network using Nios II and uClinux

2013 April 1900 (has links)
This research is focused on identifying an appropriate design for a reconfigurable Body Area Network (BAN). In order to investigate the benefits and drawbacks of the proposed design, a BAN system prototype was built. This system consists of two distinct node types: a slave node and a master node. These nodes communicate using ZigBee radio transceivers. The microcontroller-based slave node acquires sensor data and transmits digitized samples to the master node. The master node is FPGA-based and runs uClinux on a soft-core microcontroller. The purpose of the master node is to receive, process and store digitized sensor data. In order to verify the operation of the BAN system prototype and demonstrate reconfigurability, a specific application was required. Pattern recognition in electrocardiogram (ECG) data was the application used in this work and the MIT-BIH Arrhythmia Database was used as the known data source for verification. A custom test platform was designed and built for the purpose of injecting data from the MIT-BIH Arrhythmia Database into the BAN system. The BAN system designed and built in this work demonstrates the ability to record raw ECG data, detect R-peaks, calculate and record R-R intervals, detect premature ventricular and atrial contractions. As this thesis will identify, many aspects of this BAN system were designed to be highly reconfigurable allowing it to be used for a wide range of BAN applications, in addition to pattern recognition of ECG data.
328

Passivhus : Jämförelse av två väggkonstruktioner

Åberg, Filip January 2010 (has links)
Av den totala energianvändningen i Sverige och övriga EU så kommer 40 % från byggnadsbeståndet. Siffran blir alltmer omtalad och pressar automatiskt upp efterfrågan av energisnåla byggnader. Finns det enkla utföranden att sänka energiförbrukningen i byggnader på, genom att energieffektivisera byggnaden på olika sätt? Eller krävs det flera års erfarenhet samt en stor plånbok? Energimyndigheten sätter nya riktlinjer för att ett hus ska kunna kalla sig ett passivhus. Sverige delas in i tre klimatzoner och passivhus mindre än 200 m² i klimatzon III får idag högst ha en energiförbrukning på 30 kWh/m² uppvärmd yta och år. Samt 50 kWh/m² uppvärmd yta och år om passivhuset är större än 200 m². Denna rapport syftar till att jämföra två passivhusväggar i ett passivhus med samma energiprestanda och med en bruksarea på 183 m². Målet är att se hur väggarna skiljer sig i förhållande till material, energi, area och kostnad. Båda förslagen är byggda med förtillverkade isoleringselement, Besta-block respektive BBI Scandinavia element, där båda har bra energiegenskaper. Ett färdigprojekterat passivhus i norra Stockholm har en yttervägg som är 471 mm tjock, bestående av Besta-block. Passivhusväggen ersätts med en annan passivhusvägg med tjocklek 338 mm, uppbyggd med BBI Scandinavias element. Vilket resulterar till att passivhuset får en bruksarea som är 193 m2 vilket i sin tur leder till en 10,4 m2 sparad bruksarea. Samtidigt ger båda väggarna liknande energiförbrukning på 30,2 kWh/m2 bruksarea och år, respektive 30,3 kWh/m2 bruksarea och år. Energijämförandet mellan de båda väggarna är beräknade med hjälp av energiprogrammet BV2 samt Swedisols beräkningsmodeller för köldbryggor. En tredje passivhusvägg som är konstruerad med en traditionell träregelstomme jämförs också med de två andra väggtyperna men bara inom material och kostnad. Detta eftersom väggen i övrigt har liknande egenskaper som väggen försedd med Besta-block. U-värdet för alla tre exemplen är strax under 0,1 W/m2°C och relativt lika. Ändå bidrar ytterväggarna med olika stora areor, kostnad och material. Emissioner från material får inte ha en negativ effekt på dem som vistas i huset, därför är det viktigt att välja sunda material även om materialet i övrigt har bra egenskaper. En byggvarudeklaration åskådliggör en byggvaras relation till miljön i olika byggskeden. I projektet uppvisas en deklaration för en EPS-cellplast som bl.a. Besta-blocken består av. Undersökningar kan göras för att se hur mycket partiklar ett material avger till luften. Deklarationen påvisar att EPS-cellplasten avger ca 45 µg/m2h. I andra deklarationer påvisas att mineralull avger mindre än 20 µg/m2h och att linoleumgolv avger ca             110 µg/m2h.    Båda alternativen med förtillverkade isoleringselement har ett högt pris per m2 vägg, som båda kostar omkring 1600-1700 kr/m2. Den tredje passivhusväggen med träregelstomme kostar endast 422 kr/m2 och har en väggtjocklek på 483 mm.
329

OptoNet- a non-directional infrared communication link for local area networks

Liu, Dongtai 05 December 1990 (has links)
This thesis work researches the theory and application of systems performing omnidirectional, non-direct path optical data communication (ONP systems). Such systems are characterized by 1) the communication involves a local, usually circular area; 2) Obstacles are allowed between a transmitter and the receivers. This is in contrast to the point-to-point and line-of-sight communications performed by almost all existing infrared data communication or transmission systems. The elimination of the point-to-point limitation makes ONP systems suitable for optical local area networking. The feasibility of ONP systems employing infrared LEDs and silicon photo detectors has been analyzed and the performance of such systems predicted. The analysis shows that indoor ONP systems are both feasible and practical. Only a few LEDs are required to cover the entire area of a large room. Efforts have been made in finding rules for optimal design of the ONP systems. A set of design criteria and curves have been established. The theoretical analysis has been verified in a successful experiment done with OptoNet, an ONP infrared datalink for local area networks. This experimental system consists of two identical communication units employing FSK modulation and microprocessor controllers. The experiment has demonstrated that the ONP optical data communications can be realized by relatively simple electronic hardware. / Graduation date: 1991
330

Ventral Tegmental Area GABAA Receptors Mediate the Change from a Drug-naive to an Opiate- or Ethanol-deprived Motivational State

Ting-A-Kee, Ryan Anthony 31 August 2012 (has links)
A crucial question in drug addiction research concerns whether the varying reports of dopamine-independent and dopamine-dependent motivation can be integrated. According to one theory, the prior drug history of a subject — that is to say, whether they have received minimal or chronic drug exposure — determines whether opiate motivation is dependent upon the brainstem tegmental pedunculopontine nucleus (TPP) or dopamine neurotransmission. The biological analogue of this change is thought to be a switch in the signalling properties (from hyperpolarizing to depolarizing) of ventral tegmental area (VTA) gamma-aminobutyric acid subtype-A (GABAA) receptors. In this thesis, I demonstrate that the mechanisms underlying opiate motivation can be selected artificially by manipulating the signalling properties of VTA GABAA receptors, irrespective of the past drug history of the subject. Furthermore, I suggest that these same VTA GABAA receptors also play a similar role in controlling ethanol motivation. Indeed, the mechanisms underlying ethanol motivation can be doubly dissociated in a manner similar to that observed with opiates. However, whereas opiate motivation is TPP-dependent in the drug-naive state, I found that ethanol motivation was dependent on dopamine neurotransmission (via the D2 receptor) in drug-naive animals. Conversely, ethanol motivation was TPP-dependent in ethanol-deprived mice (as opposed to opiate motivation being dopamine-dependent in opiate-deprived animals). These effects are consistent with a VTA GABAA receptor switching mechanism identical to the one seen in the case of opiate motivation.

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