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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.
801

Testing methods for calibrating Forest Vegetation Simulator (FVS) diameter growth predictions

Cankaya, Ergin Cagatay 20 September 2018 (has links)
The Forest Vegetation Simulator (FVS) is a growth and yield modeling system widely-used for predicting stand and tree-level attributes for management and planning applications in North American forests. The accuracy of FVS predictions for a range of tree and stand level attributes depends a great deal on the performance of the diameter increment model and its predictions of change in diameter at breast height (DBH) over time. To address the challenge of predicting growth in highly variable and geographically expansive forest systems, FVS was designed to include an internal calibration algorithm that makes use of growth observations, when available, from permanent inventory plots. The basic idea is that observed growth rates on a collection of remeasured trees are used to adjust or "calibrate" FVS diameter growth predictions. Therefore, DBH modeling was the focus of this investigation. Five methods were proposed for local calibration of individual tree DBH growth predictions and compared to two sets of results generated without calibration. Data from the US Forest Service's Forest Inventory and Analysis (FIA) program were used to test the methods for eleven widely-distributed forest tree species in Virginia. Two calibration approaches were based on median prediction errors from locally-observed DBH increments spanning a five year average time interval. Two were based on simple linear regression models fitted to the locally-observed prediction errors, and one method employed a mixed effects regression model with a random intercept term estimated from locally-observed DBH increments. Data witholding, specifically a leave-one-out cross-validation was used to compare results of the methods tested. Results showed that any of the calibration approaches tested in general led to improved accuracy of DBH growth predictions, with either of the median-based methods or regression based methods performing better than the random-effects-based approach. Equivalence testing showed that median or regression-based local calibration methods met error tolerances within ± 12% of observed DBH increments for all species with the random effects approach meeting a larger tolerance of ± 17%. These results showed improvement over uncalibrated models, which failed to meet tolerances as high as ± 30% for some species in a newly-fitted DBH growth model for Virginia, and as high as ± 170% for an existing model fitted to data from a much larger region of the Southeastern United States. Local calibration of regional DBH increment models provides an effective means of substantially reducing prediction errors when a relatively small set of observations are available from local sources such as permanent forest inventory plots, or the FIA database. / MS / The Forest Vegetation Simulator (FVS) is a growth and yield model widely-used for predicting stand dynamics, management and decision support in North American forests. Diameter increment is a major component in modeling tree growth. The system of integrated analytical tools in FVS is primarily based on the performance of the diameter increment model and the subsequent use of predicted in diameter at breast height (DBH) over time in forecasting tree attributes. To address the challenge of predicting growth in highly variable and geographically expansive forest systems, FVS was designed to include an internal calibration algorithm that makes use of growth observations, when available, from permanent inventory plots. The basic idea was that observed growth rates on a small set of remeasured trees are used to adjust or “calibrate” FVS growth predictions. The FVS internal calibration was the subject being investigated here. Five alternative methods were proposed attributed to a specific site or stand of interest and compared to two sets of results, which were based on median prediction errors, generated without calibration. Results illustrated that median-based methods or regression based methods performed better than the random-effects-based approach using independently observed growth data from Forest Service FIA re-measurements in Virginia. Local calibration of regional DBH increment models provides an effective means of substantially reducing prediction errors. The results of this study should also provide information to evaluate the efficiency of FVS calibration alternatives and a possible method for future implementation.
802

Statistical analysis of corrective and preventive maintenance in medical equipment

von Schewelov, Linn January 2022 (has links)
Maintenance of medical equipment plays an important role in ensuring the healthcare quality so that the care can be conducted with minimal risk. Preventive maintenance is performed to maintain the equipment in satisfactory operating condition, while corrective maintenance is made when there is an unpredicted maintenance requirement. This study aims to determine what effect preventive maintenance has on corrective maintenance. A correlation analysis, regression analysis and survival analysis are performed on work-order data from 2000-2021. The results obtained indicate that increasing the number of preventive maintenances made to medical equipment will decrease the number of corrective maintenances required for the medical equipment.
803

Women’s experiences of immigration detention in Italy: examining immigration procedural fairness, human dignity, and health

Esposito, F., Di Martino, Salvatore, Briozzo, E., Arcidiacono, C., Ornelas, J. 14 July 2022 (has links)
Yes / Recent decades have witnessed a growing number of states around the world relying on border control measures, such as immigration detention, to govern human mobility and control the movements of those classified as “unauthorised non-citizens.” In response to this, an increasing number of scholars from several disciplines, including psychologists, have begun to examine this phenomenon. In spite of the widespread concerns raised, few studies have been conducted inside immigration detention sites, primarily due to difficulties in gaining access. This body of research becomes even scanter when it comes to the experiences of detained women. This study is the first of its kind to have surveyed 93 women confined in an Italian immigration detention facility. A partial mediation model with latent variables was tested through partial least structural equation modelling (PLS-SEM). The findings revealed the negative impact that unfair immigration procedures have on detained women’s human dignity, which in turn negatively affects their self-rated physical and mental health. Overall, our study sheds light on the dehumanisation and damage to human dignity that immigration detention entails, as well as its negative impact on the health of those affected. This evidence reinforces the image of these institutions as sites of persistent injustice, while stressing the need to envision alternative justice-oriented forms to address human mobility. / FE’s doctoral research, on which this article relies, was supported by the Portuguese Foundation for Science and Technology (SFRH/BD/87854/2012), and her subsequent work was supported by the Portuguese Foundation for Science and Technology (grant number: CEECIND/00924/2018/CP1541/CT0004).
804

A multi-case study of secondary principal practices supporting co-teaching in the context of the least restrictive environment

Howser, Debora L. January 1900 (has links)
Doctor of Education / Department of Educational Leadership / Trudy A. Salsberry / Educational leadership is challenged with meeting the requirements of No Child Left Behind (NCLB) of 2001 and Individuals with Disabilities Education Improvement Act (IDEIA) of 2004. The focus on accessibility and accountability is resulting in an increase in the number of students with disabilities receiving specialized instruction within the least restrictive environment (LRE) of the general education classroom. To support students in the LRE, many schools are implementing the service delivery model of co-teaching, or pairing a special educator with a general educator, to provide core instruction with appropriate special education services to students with special needs. The purpose of this case study was to investigate what practices of principals are deemed most supportive to teachers engaged in a co-teaching service delivery model. The qualitative, multi-case study was designed to analyze perceptions of district level general education administrators, district level special education administrators, building principals, co-teaching coaches, and co-teaching partners who participated in the Kansas Co-Teaching Initiative. Data were obtained primarily through interviews of the participants. Demographic surveys, building schedules and field notes served as additional information for analysis and the interpretation of the data. The over-arching research question for this study was: “What practices of principals provide the most meaningful support to collaborative co-teaching in the context of the least restrictive environment?” Sheard and Kakabadse’s nine Key Elements of Effective Teams (2002, 2004) formed the framework for the study. These key elements also guided the research sub-questions. Data collected through the study revealed sixty patterns across the key elements of effective teams. When analyzed, the patterns yielded three themes: 1) principals arranged and protected time during the daily schedule for collaboration between co-teaching partners, 2) principals paired co-teachers together with careful consideration for compatibility, and 3) principals established and maintained a culture of professional growth.
805

Analysis of Fix‐point Aspects for Wireless Infrastructure Systems

Grill, Andreas, Englund, Robin January 2009 (has links)
A large amount of today’s telecommunication consists of mobile and short distance wireless applications, where the effect of the channel is unknown and changing over time, and thus needs to be described statistically. Therefore the received signal can not be accurately predicted and has to be estimated. Since telecom systems are implemented in real-time, the hardware in the receiver for estimating the sent signal can for example be based on a DSP where the statistic calculations are performed. A fixed-point DSP with a limited number of bits and a fixed binary point causes larger quantization errors compared to floating point operations with higher accuracy. The focus on this thesis has been to build a library of functions for handling fixed-point data. A class that can handle the most common arithmetic operations and a least squares solver for fixed-point have been implemented in MATLAB code. The MATLAB Fixed-Point Toolbox could have been used to solve this task, but in order to have full control of the algorithms and the fixed-point handling an independent library was created. The conclusion of the simulation made in this thesis is that the least squares result are depending more on the number of integer bits then the number of fractional bits. / En stor del av dagens telekommunikation består av mobila trådlösa kortdistanstillämpningar där kanalens påverkan är okänd och förändras över tid. Signalen måste därför beskrivas statistiskt, vilket gör att den inte kan bestämmas exakt, utan måste estimeras. Eftersom telekomsystem arbetar i realtid består hårdvaran i mottagaren av t.ex. en DSP där de statistiska beräkningarna görs. En fixtals DSP har ett bestämt antal bitar och fast binärpunkt, vilket introducerar ett större kvantiseringsbrus jämfört med flyttalsoperationer som har en större noggrannhet. Tyngdpunkten på det här arbetet har varit att skapa ett bibliotek av funktioner för att hantera fixtal. En klass har skapats i MATLAB-kod som kan hantera de vanligaste aritmetiska operationerna och lösa minsta-kvadrat-problem. MATLAB:s Fixed-Point Toolbox skulle kunna användas för att lösa den här uppgiften men för att ha full kontroll över algoritmerna och fixtalshanteringen behövs ett eget bibliotek av funktioner som är oberoende av MATLAB:s Fixed-Point Toolbox. Slutsatsen av simuleringen gjord i detta examensarbete är att resultatet av minsta-kvadrat-metoden är mer beroende av antalet heltalsbitar än antalet binaler. / fixtal, telekommunikation, DSP, MATLAB, Fixed-Point Toolbox, minsta-kvadrat-lösning, flyttal, Householder QR faktorisering, saturering, kvantiseringsbrus
806

The relationship between inflation and economic growth in Ethiopia

Abis Getachew Makuria 14 July 2014 (has links)
The main purpose of this study is to empirically assess the relationship between inflation and economic growth in Ethiopia using quarterly dataset from 1992Q1 to 2010Q4. In doing so, an interesting policy issue arises. What is the threshold level of inflation for the Ethiopian economy? Based on the Engle-Granger and Johansen co-integration tests it is found out that there is a positive long-run relationship between inflation and economic growth. The error correction models show that in cases of short-run disequilibrium, the inflation model adjusts itself to its long-run path correcting roughly 40% of the imbalance in each quarter. In addition, based on the conditional least square technique, the estimated threshold model suggests 10% as the optimal level of inflation that facilitates growth. An inflation level higher or lower than the threshold level of inflation affects the economic growth negatively and hence fiscal and monetary policy coordination is vital to keep inflation at the threshold. / Economics / M. Com. (Economics)
807

Online traffic engineering for MPLS networks

Botha, Marlene 4 1900 (has links)
Thesis (MSc) -- Stellenbosch University, 2004. / ENGLISH ABSTRACT: The Internet is fast evolving into a commercial platform that carries a mixture of narrow- and broadband applications such as voice, video, and data. Users expect a certain level of guaranteed service from their service providers and consequently the need exists for efficient Internet traffic engineering to enable better Quality of Service (QoS) capabilities. Multi-protocol Label Switching (MPLS) is a label switching protocol that has emerged as an enabling technology to achieve efficient traffic engineering for QoS management in IP networks. The ability of the MPLS protocol to create explicit virtual connections called Label Switched Paths (LSPs) to carry network traffic significantly enhances the traffic engineering capabilities of communication networks. The MPLS protocol supports two options for explicit LSP selection: offline LSP computation using an optimization method and dynamic route selection where a single node makes use of current available network state information in order to compute an explicit LSP online. This thesis investigates various methods for the selection of explicit bandwidth guaranteed LSPs through dynamic route selection. We address the problem of computing a sequence of optimal LSPs where each LSP can carry a specific traffic demand and we assume that no prior information regarding the future traffic demands are available and that the arrival sequence of LSP requests to the network is unknown. Furthermore, we investigate the rerouting abilities of the online LSP selection methods to perform MPLS failure restoration upon link failure. We propose a new online routing framework known as Least Interference Optimization (LIO) that utilizes the current bandwidth availability and traffic flow distribution to achieve efficient traffic engineering. We present the Least Interference Optimization Algorithm (LIOA) that reduces the interference among competing network flows by balancing the number and quantity of flows carried by a link for the setup of bandwidth guaranteed LSPs in MPLS networks. The LIOA routing strategy is evaluated and compared against well-known routing strategies such as the Minimum Hop Algorithm (MHA), Minimum Interference Routing Algorithm (MIRA), Open Shortest Path First (OSPF) and Constraint Shortest Path First (CSPF) by means of simulation. Simulation results revealed that, for the network topologies under consideration, the routing strategies that employed dynamic network state information in their routing decisions (LIOA, CSPF and MIRA) generally outperformed the routing strategies that only rely on static network information (OSPF and MHA). In most simulation experiments the best performance was achieved by the LIOA routing strategy while the MHA performed the worse. Furthermore we observed that the computational complexity of the MIRA routing strategy does not translate into equivalent performance gains. We employed the online routing strategies for MPLS failure recovery upon link failure. In particular we investigated two aspects to determine the efficiency of the routing strategies for MPLS rerouting: the suitability of the LSP configuration that results due to the establishment of LSPs prior to link failure and the ability of the online routing strategy to reroute failed LSPs upon link failure. Simulation results revealed similar rerouting performance for all online routing strategies under investigation, but a LSP configuration most suitable for online rerouting was observed for the LIOA routing strategy. / AFRIKAANSE OPSOMMING:Die Internet is voordurend besig om te evoleer in 'n medium wat 'n wye reeks moderne kommunikasietegnologiee ondersteun, insluitende telefoon, video en data. Internet gebruikers verwag gewaarborgde diens van hul diensverskaffers en daar bestaan dus 'n vraag na doeltreffende televerkeerbeheer vir gewaarborgde Internet diensgehalte. Multiprotokol Etiketskakeling (MPLS) is 'n etiketskakeling protokol wat doeltreffende televerkeerbeheer en diensgehalte moontlik maak deur die eksplisiete seleksie van virtuele konneksies vir die transmissie van netwerkverkeer in Internetprotokol (IP) netwerke. Hierdie virtuele konneksies staan bekend as etiketgeskakelde paaie. Die MPLS protokol ondersteun tans twee moontlikhede vir eksplisiete seleksie van etiketgeskakelde paaie: aflyn padberekening met behulp van optimeringsmetodes en dinamiese aanlyn padseleksie waar 'n gekose node 'n eksplisiete pad bereken deur die huidige stand van die netwerk in ag te neem. In hierdie tesis word verskeie padseleksiemetodes vir die seleksie van eksplisiete bandwydte-gewaarborgde etiketgeskakelde paaie deur mid del van dinamiese padseleksie ondersoek. Die probleem om 'n reeks optimale etiketgeskakelde paaie te bereken wat elk 'n gespesifeerde verkeersaanvraag kan akkommodeer word aangespreek. Daar word aanvaar dat geen informasie in verband met die toekomstige verkeersaanvraag bekend is nie en dat die aankomsvolgorde van etiketgeskakelde pad verso eke onbekend is. Ons ondersoek verder die herroeteringsmoontlikhede van die aanlyn padseleksiemetodes vir MPLS foutrestorasie in die geval van skakelonderbreking. Vir hierdie doel word 'n nuwe aanlyn roeteringsraamwerk naamlik Laagste Inwerking Optimering (LIO) voorgestel. LIO benut die huidige beskikbare bandwydte en verkeersvloeidistribusie van die netwerk om doeltreffende televerkeerbeheer moontlik te maak. Ons beskryf 'n Laagste Inwerking Optimering Algoritme (LIOA) wat die inwerking tussen kompeterende verkeersvloei verminder deur 'n balans te handhaaf tussen die aantal en kwantiteit van die verkeersvloeistrome wat gedra word deur elke netwerkskakel. Die LIOA roeteringstrategie word geevalueer met behulp van simulasie en die resultate word vergelyk met ander bekende roeteringstrategiee insluitende die Minimum Node Algorithme (MHA), die Minimum Inwerking Algoritme (MIRA), die Wydste Kortste Pad Eerste Algoritme (OSPF) en die Beperkte Kortste Pad Eerste Algoritme (CSPF). Die resultate van die simulasie-eksperimente to on dat, vir die netwerk topologiee onder eksperimentasie, die roeteringstratgiee wat roeteringsbesluite op dinamiese netwerk informasie baseer (LIOA, MIRA, CSPF) oor die algemeen beter vaar as die wat slegs staatmaak op statiese netwerkinformasie (MHA, OSPF). In die meeste simulasie-eksperimente vaar die LIOA roeteringstrategie die beste en die MHA roeteringstrategie die slegste. Daar word verder waargeneem dat die komputasiekomplesiteit van die MIRA roeteringstrategie nie noodwendig weerspieel word in die sukses van roeteringsuitkoms nie. In die geval waar die aanlyn roeteringstrategiee aangewend word vir MPLS foutrestorasie, toon die resultate van simulasie-eksperimente dat al die roeteringstrategiee min of meer dieselfde uitkoms lewer ten opsigte van herroetering van onderbreekte verkeersvloei. Die konfigurasie van etiketgeskakelde paaie deur die LIOA roeteringstrategie voor skakelonderbreking is egter die geskikste vir televerkeer herroetering na skakelonderbreking
808

Detection and quantification of poliovirus infection using FTIR spectroscopy and cell culture

Lee-Montiel, Felipe, Reynolds, Kelly, Riley, Mark January 2011 (has links)
BACKGROUND:In a globalized word, prevention of infectious diseases is a major challenge. Rapid detection of viable virus particles in water and other environmental samples is essential to public health risk assessment, homeland security and environmental protection. Current virus detection methods, especially assessing viral infectivity, are complex and time-consuming, making point-of-care detection a challenge. Faster, more sensitive, highly specific methods are needed to quantify potentially hazardous viral pathogens and to determine if suspected materials contain viable viral particles. Fourier transform infrared (FTIR) spectroscopy combined with cellular-based sensing, may offer a precise way to detect specific viruses. This approach utilizes infrared light to monitor changes in molecular components of cells by tracking changes in absorbance patterns produced following virus infection. In this work poliovirus (PV1) was used to evaluate the utility of FTIR spectroscopy with cell culture for rapid detection of infective virus particles.RESULTS:Buffalo green monkey kidney (BGMK) cells infected with different virus titers were studied at 1 - 12 hours post-infection (h.p.i.). A partial least squares (PLS) regression method was used to analyze and model cellular responses to different infection titers and times post-infection. The model performs best at 8 h.p.i., resulting in an estimated root mean square error of cross validation (RMSECV) of 17 plaque forming units (PFU)/ml when using low titers of infection of 10 and 100 PFU/ml. Higher titers, from 103 to 106 PFU/ml, could also be reliably detected.CONCLUSIONS:This approach to poliovirus detection and quantification using FTIR spectroscopy and cell culture could potentially be extended to compare biochemical cell responses to infection with different viruses. This virus detection method could feasibly be adapted to an automated scheme for use in areas such as water safety monitoring and medical diagnostics.
809

Creating opportunity by connecting the unconnected : mobile phone based agriculture market information service for farmers in Bangladesh

Islam, M. Sirajul January 2011 (has links)
This thesis is framed within the research area of Information and Communication Technologies for Development (ICT4D), which is concerned with how ICT can make a difference to the lives of the poor. This study focuses primarily on mobile phones and how they can be used as part of an Agriculture Market Information Service (AMIS) in order to provide crucial information to farmers in Bangladesh. AMIS principally collect, manage and disseminate agricultural market prices and related information through various processes and media. These services are mainly used by farmers. The research question of how mobile phone-based AMIS can be designed and deployed in order to improve opportunities for farmers in Bangladesh is investigated through a design science research approach in four steps; understanding the scope and challenges related to AMIS in least developed countries; diagnosing the situational realities of farmers of Bangladesh; understanding the process of adopting mobile phones and investigating market information practices and preferences in a rural context; and finally designing and implementing a mobile phone based AMIS and evaluating the efficiency and effectiveness of it for the farmers of Bangladesh. In this thesis, development is viewed in terms of bringing about an in-crease in farmers’ capability set directed towards the utilization of resources for the purpose of production and trade. Information and knowledge are important drivers of development and poverty reduction: ICT can create new opportunities to expand the availability, exchange, and impact of information and knowledge. This thesis contributes to ICT4D research and practice through empirical findings, the design of an AMIS, test results, and the development of analytical tools. Its major contributions include an increased understanding of farmers’ attitudes and preferences towards the use of technology in general, and mobile phones in particular, and a broader understanding of ICT for human development in the context of poor rural regions. / Informatics or ICT4D
810

Topic Analysis of Tweets on the European Refugee Crisis Using Non-negative Matrix Factorization

Shen, Chong 01 January 2016 (has links)
The ongoing European Refugee Crisis has been one of the most popular trending topics on Twitter for the past 8 months. This paper applies topic modeling on bulks of tweets to discover the hidden patterns within these social media discussions. In particular, we perform topic analysis through solving Non-negative Matrix Factorization (NMF) as an Inexact Alternating Least Squares problem. We accelerate the computation using techniques including tweet sampling and augmented NMF, compare NMF results with different ranks and visualize the outputs through topic representation and frequency plots. We observe that supportive sentiments maintained a strong presence while negative sentiments such as safety concerns have emerged over time.

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