To see the other types of publications on this topic, follow the link: Improvement of accuracy.
Dissertations / Theses on the topic 'Improvement of accuracy'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Improvement of accuracy.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Han, Zhao. "Accuracy improvement of stereolithography." Thesis, University of Liverpool, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.486424.
Full textAbstract:
The basic layer-based manufacturing mechanism of stereolithography is built upon a scanning pattern for the entire cross section for each layer. The purpose of this research is to investigate experimentally and theoretically the effects of a new scanning pattern with the aim of improving the dimensional and geometrical performance of Stereolithography against a benchmarked industry standard scanning pattern. The development of the new Bisector scanning patterns is based on the hypothesis that a contour-oriented scanning sequence with more built-in relaxation could provide a more uniform distribution of residual stress caused by the intrinsic phase transformation due to the photopolymerization process. Experiments on a variety of geometries showed that the new scanning pattern offers substantial improvements in terms of dimensional accuracy, part flatness, surface profile and the system running cost. This further insight into the effects of the scanning patterns was gained through the use of Finite Element (FE) modelling. A commercial FE package ABAQUS was employed to develop thermo-mechanical analogous models to ~nalyse and compare the stresses, strains and distortion induced by each pattern. For the Bisector scanning pattern, the scanning direction and length of scanning vectors are more symmetrical distributed in X and Y axes and hence the distortion or curl occurs in both axes and is comparatively less than that observed for the STAR-WEAVE scanning pattern. If the same overall shrinkage is distributed in both axes then the net distortion must be reduced. The modelling results are consistent with the experimental results of this research, in that the amount of distortion on Bisector scanning patterns is less than the STAR-WEAVE scanning pattern.
2
Saravi, Mohammad Ebrahimzadeh. "Improving cost estimation accuracy through quality improvement techniques." Thesis, University of Bath, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.520948.
Full text
3
Johnsrud, Vegard. "Improvement of the Positioning Accuracy of Industrial Robots." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for produksjons- og kvalitetsteknikk, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-26243.
Full textAbstract:
Industriroboter er godt kjent for sin høye repeterbarhet, noe som reflekteres i deres hovedbruksområde i industrien, deriblant ”pick and place”-operasjoner og punktsveising. Med det økende behovet for automatisering i industrien, representerer roboter en unik mulighet for nettopp dette uten å redusere fleksibiliteten. Som det imidlertid påpekes i denne masteroppgaven, ligger hovedutfordringen for industriroboter i å forbedre dårlig posisjoneringsnøyaktighet. For å løse denne utfordringen kan man endre på robotens mekaniske utforming, men et mer gjennomførbart alternativ er å forbedre eller endre programvaren i robotens styreenhet. Det siste alternativet er bedre kjent som robotkalibrering, og er metoden som benyttes i denne oppgaven. For at posisjoneringsnøyaktigheten til en industrirobot skal forbedres, bør formålet med kalibreringen være å redusere hovedårsaken til dårlig posisjoneringsnøyaktighet. Dette handler i de fleste tilfeller om robotleddenes vinkelforskyvningsfeil, også kalt offset-feil. I de praktiske implementeringene i denne masteroppgaven, utføres offset-kalibrering ved hjelp av en flensmontert laser avstandssensor og en plan flate som kalibreringsobjekt. Masteroppgaven tar utgangspunkt i en matematisk modell basert på robotens kinematiske modell, en enkoder-leddmodell, en lasersensormodell og en plan modell. Den matematiske modellen benyttes for å sette opp en beregningsmodell for laseravstandsmålingen som en funksjon av leddvinkler og de øvrige modellparameterne. Der de interessante modellparameterne er leddforskyvninger (offsets), som skal korrigere for leddenes vinkelforskyvningsfeil. For å utvikle en optimal modell som best beskriver det virkelige oppsettet, er det utført flere datainnsamlinger bestående av ulike avstandsmålinger mellom laser og plan med tilhørende vinkelkonfigurasjoner for roboten. Avslutningsvis er det brukt en minstekvadratersmetode optimeringsalgoritme for å identifisere hvilke modellparametere som gir minst avvik mellom beregningsmodellen og faktiske målinger fra datasettet. Fra dette får man leddforskyvningskorreksjonen man er ute etter.Implementeringen er realisert ved å utvikle to LabVIEW-applikasjoner; én for å utføre datainnsamlingen og én for utførelse av optimalisering. Datainnsamlingsapplikasjonen bruker ”fjernkontroll” for styring og kommunikasjon av roboten, der den lager et tilfeldig utvalg av robotpositurer med tilhørende lasermåling mot et plan. For hver positur lagres robotleddenes posisjon i enkoderverdier og laserens avstandsmåling til et datasett. I optimaliseringsapplikasjonen brukes datasettet fra innsamlingen til å optimalisere beregningsmodellen, noe som resulterer i nye modellparametere og dermed også leddforskyvingskorreksjon. Masteroppgaven presenterer beregningsmodellens prinsipp og hvordan den er tilegnet bruk på det faktiske oppsettet i forskningsanlegget til PPM AS, samt inneholder tester for å verifisere beregningsmodellen og kalibreringsprinsippet. Testene viser at beregningsmodellen er overførbar til andre robotmodeller, og at den gir en bedre tilpasning til innsamlede data ved bruk av oppdaterte modellparametere funnet i kalibreringen. Testene viser også hvordan parameterkorreksjon i kalibreringen svinger mellom de forskjellige datasettene, noe som belyser behovet for en statistisk analyse av kalibreringsresultatene. På grunn av tidsbegrensninger for gjennomføring av oppgaven, ble den statistiske analysen og endelig valideringsforsøk av den kalibrerte roboten ikke oppnådd. Oppgaven har imidlertid en egen seksjon som beskriver hvordan videre arbeid bør foregå.
4
Gandhi, Anall Vijaykumar. "An Accuracy Improvement Method for Cricket Indoor Location System." Wright State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=wright1369316496.
Full text
5
Yang, Po. "Accuracy improvement of RFID based 2D tracking and localisation." Thesis, Staffordshire University, 2011. http://eprints.staffs.ac.uk/1884/.
Full textAbstract:
The purpose of localization and tracking technology in indoor application is to extract moving object parameters accurately and precisely. This thesis investigates the problem of how to utilize RFID technique for the accurate and precise extraction of indoor 2D moving object position parameters. Firstly, a framework named RFID-Loc with three modules: RFID-Loc Infrastructure, RFID-Loc Data Filter and RFID-Loc Localisation Algorithm, is established from a theoretical perspective. This framework can guide the research and design of methods used in an RFID based object localisation system with enhanced localisation accuracy and precision. Secondly, from practical perspective, few methods are proposed in RFID-Loc framework to improve the localisation accuracy and precision. A sparse RFID Tag Arrangement strategy is proposed in this RFID-Loc framework, aiming at reducing the impacts of regular false reading error from RFID infrastructure level on localisation precision. The efficiency of this methods and the assumptions upon which it relies, are investigated empirically. A rectangle-based feature selection method is justified as the major RFID Data Filter algorithm, with the capability of maximally reducing regular false reading errors. The possibility to resist unexpected false reading error in an RFID-Loc system is investigated by discussing and comparing several RFID-based localisation algorithms. A dynamic localisation algorithm for RFID-Loc system is proposed to accurately and precisely extract moving object position parameters overtime in an RFID-Loc system. This algorithm is shown to have a better capability of resisting unexpected false reading error than conventional localisation algorithms used in RFID-based localisation systems, while having a higher computational complexity. By following the theoretical guidelines in RFID-Loc framework and implementing the proposed methods, the experimental results demonstrate that the localisation accuracy and precision can be significantly improved, up to 10 centimetres and 3 centimetres under current RFID devices.
6
Ahmad, Ali Mohsin. "Digital terrain models in engineering : assessment and improvement of accuracy." Thesis, University of Newcastle Upon Tyne, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278756.
Full text
7
Lee, Jaehong. "Improvement of Experimental Data Accuracy for Neutron Capture Cross Section." Kyoto University, 2018. http://hdl.handle.net/2433/232482.
Full text
8
Zhao, Qiuying. "Towards Improvement of Numerical Accuracy for Unstructured Grid Flow Solver." University of Toledo / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1353107603.
Full text
9
Borm, Jin-Hwan. "Improvement and characterization of robot positioning accuracy for off-line programming /." The Ohio State University, 1988. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487596307357735.
Full text
10
Eriksson, Peter. "Milling accuracy improvement of a 6-axis industrial robot through dynamic analysis : From datasheet to improvement suggestions." Thesis, KTH, MWL Marcus Wallenberg Laboratoriet, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-250244.
Full textAbstract:
The industrial robot is a flexible and cheap standard component that can becombined with a milling head to complete low accuracy milling tasks. Thefuture goal for researchers and industry is to increase the milling accuracy, suchthat it can be introduced to more high value added operations.The serial build up of an industrial robot bring non-linear compliance andchallenges in vibration mitigation due to the member and reducer design. WithAdditive Manufacturing (AM), the traditional cast aluminum structure couldbe revised and, therefore, milling accuracy gain could be made possible due tostructural changes.This thesis proposes the structural changes that would improve the millingaccuracy for a specific trajectory. To quantify the improvement, first the robothad to be reverse engineered and a kinematic simulation model be built. Nextthe kinematic simulation process was automated such that multiple input parameterscould be varied and a screening conducted that proposed the mostprofitable change.It was found that a mass decrease in any member did not affect the millingaccuracy and a stiffness increase in the member of the second axis would increasethe milling accuracy the most, without changing the design concept. To changethe reducer in axis 1 would reduce the mean position error by 7.5 % and themean rotation error by 4.5 % approximately, but also reduces the maximumspeed of the robot. The best structural change would be to introduce twosupport bearings for axis two and three, which decreased the mean positioningerror and rotation error by approximately 8 % and 13 % respectively.En industrirobot är en anpassningsbar och relativt billig standardkomponent.Den kan utrustas med ett fräshuvud för att genomföra fräsoperationer med låg noggrannhet. Det framtida målet för forskare och industri är att öka noggrannheten vid fräsning så att dess användningsområde kan utökas till ändamål som kräver högre precision.Den seriella uppbyggnaden av en industrirobot medför icke-linjär styvhet och därmed utmaningar vid vibrationsdämpning. Detta på grund av den strukturella uppbyggnaden då en industrirobot kan förenklat sägas vara uppbyggd av balkelement som i ledpunkterna kopplas samman av växellådor. Med friformsframställning kan en mer komplex struktur erhållas jämfört med traditionellt gjuten aluminiumkonstruktion därmed skulle en ökad noggrannhet vid fräsning kunna uppnås.Det här examensarbetet föreslår strukturella ändringar som skulle kunna öka noggrannheten vid fräsning för en specifik fräsbana. För att kvantifiera förbättringen, var det först nödvändigt att utgående från tillgänglig data konstruktion en specific robot samt att bygga en kinematisk modell. Därefter automatiserades beräkningsflödet så att ett flertal indata kunde varieras. Detta resulterande i en kombinationsstudie som visade den mest gynsamma strukturella förändringen.Det visade sig att en minskning av balkelementens massa inte påverkade nogrannheten. Att öka styvheten i balkelementet från den andra axeln skulle d¨aremot öka nogrannheten mest utan att behöva ändra robotens uppbyggnad.Att byta växellåda i första axeln kan öka positionsnogrannheten med nära 7.5 % och rotationsnoggrannheten med cirka 4.5 % men ändringen sänker samtidigt den maximala hastigheten. Den bästa strukturella förändringen vore att introducera ett stödlager vid axel två respektive tre, vilket skulle förbättra positionsnogrannheten med cirka 8 % och rotationsnogrannheten med nära 13 %.
11
Bian, Chao. "Improvement of RFID tracking accuracy for a personnel tracking system in healthcare." The American Society of Mechanical Engineers, 2013. http://hdl.handle.net/1993/24053.
Full textAbstract:
Radio Frequency Identification (RFID) technology has been widely adopted by different industries for various purposes. While implementing a RFID system for personnel tracking in an industrial environment, such as a hospital, the tracking accuracy is not always satisfactory due to incorrect placement of RFID hardware, coarse system configuration or environment. This thesis proposes comprehensive optimization methods for improving the tracking accuracy of a RFID system for personnel tracking. The improvement is achieved from four perspectives including RFID data cleaning, experimental design, data fusion and simulation modeling. This research is based on a case study carried out in a local community hospital where a RFID system for personnel tracking has been implemented. Through applying the optimization methods, the tracking accuracy of the RFID system has been improved to 87.33%. The thesis provides a guideline for the hospital and other similar application environment to implement improvement methods on a RFID tracking system.
12
Do, Changhee. "Improvement in accuracy using records lacking sire information in the animal model." Diss., Virginia Tech, 1992. http://hdl.handle.net/10919/39430.
Full text
13
Lin, Shuding. "A Study on Measurement and Improvement of the Contouring Accuracy of NC Machine Tools." Kyoto University, 1999. http://hdl.handle.net/2433/181319.
Full text
14
Khurshid, Zain [Verfasser]. "Improvement in the accuracy of PET Signals by Analysis of Textural heterogeneity parameters / Zain Khurshid." Bonn : Universitäts- und Landesbibliothek Bonn, 2018. http://d-nb.info/1170872417/34.
Full text
15
Ishitsuka, Kazuya. "Synthetic Aperture Radar Interferometry Time-series for Surface Displacement Monitoring: Data interpretation and improvement in accuracy." 京都大学 (Kyoto University), 2015. http://hdl.handle.net/2433/199261.
Full text
16
Wang, Dewei. "Uncertainty Quantification and Accuracy Improvement of the Double-Sensor Conductivity Probe for Two-Phase Flow Measurement." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/103074.
Full textAbstract:
The double-sensor conductivity probe is one of the most commonly used techniques for obtaining local time-averaged parameters in two-phase flows. The uncertainty of this measurement technique has not been well understood in the past as it involves many different steps and influential factors in a typical measurement. This dissertation aims to address this gap by performing a systematic and comprehensive study on the measurement uncertainty of the probe. Three types of uncertainties are analyzed: that of measurands, of the model input parameters, and of the mathematical models. A Monte Carlo uncertainty evaluation framework closely simulating the actual measuring process is developed to link various uncertainty sources to the time-averaged two-phase flow quantities outputted by the probe. Based on the Monte Carlo uncertainty evaluation framework, an iteration method is developed to infer the true values of the quantities that are being measured. A better understanding of the uncertainty of the double-sensor conductivity probe is obtained.
Multiple advanced techniques, such as high speed optical imaging and fast X-ray densitometry, recently become mature and easily accessible. To further improve the accuracy of local two-phase flow measurement, a method is developed to integrate these techniques with the double-sensor conductivity probe by considering the measuring principles and unique advantages of each technique. It has been demonstrated that after processing and synergizing the data from different techniques using the current integration method, the final results show improved accuracy for void fraction, gas velocity and superficial gas velocity, compared to the original probe measurements.
High-resolution two-phase flow data is essential for the further development of various two-phase flow models and validation of two-phase CFD codes. Therefore, a comprehensive high-accuracy database of two-phase flows is acquired. The gas-phase information is obtained by the integration method developed in this dissertation, and the recently developed Particle Image Velocimetry and Planar Laser Induced Fluorescence (PIV-PLIF) technique is utilized to measure liquid-phase velocity and turbulence characteristics. Flow characteristics of bubbly flow, slug flow and churn-turbulent flow are investigated. The 1-D drift-flux model is re-evaluated by the newly obtained dataset. The distribution parameter model has been optimized based on a new void-profile classification method proposed in this study. The optimized drift-flux model has significant improvements in predicting both gas velocity and void fraction.Doctor of Philosophy
The double-sensor conductivity probe is one widely used technique for measuring local time-averaged parameters in two-phase flows. Although a number of studies have been carried out in the past, a good understanding of the uncertainty of this technique is still lacking. This paper aims to address this gap by performing a systematic and comprehensive study on the measurement uncertainty of the probe. Three types of uncertainties are analyzed: that of measurands, of the model input parameters, and of the mathematical models. A better understanding of the uncertainty of the double-sensor conductivity probe has been obtained. Considering the unique measuring principles and advantages of multiple advanced techniques, a method is developed to integrate these techniques with the double-sensor conductivity probe to further improve the accuracy of local two-phase flow measurement. It has been demonstrated that the integration method significantly improves the accuracy of probe measurements. Realizing the needs of high-resolution two-phase flow data to the further development of various two-phase flow models and validation of two-phase CFD codes, a comprehensive database of two-phase flows is acquired. The gas-phase and liquid-phase information are acquired by the new integration method and the recently developed Particle Image Velocimetry and Planar Laser Induced Fluorescence (PIV-PLIF) technique, respectively. The classical 1-D drift-flux model is re-evaluated by the newly obtained dataset. The distribution parameter model has been optimized, resulting in significant improvements in predicting both gas velocity and void fraction.
17
Henrico, Ivan. "Geometric accuracy improvement of VHR satellite imagery during orthorectification with the use of ground control points." Thesis, University of Pretoria, 2016. http://hdl.handle.net/2263/60812.
Full textAbstract:
Conducting single frame orthorectification on satellite images to create an ortho-image requires four basic components, namely an image, a geometric sensor model, elevation data (for example a digital elevation model (DEM)) and ground control points (GCPs). For this study, orthorectification was executed numerous times (in three stages) and each time components were altered to test the geometric accuracy of the resulting ortho-image. Most notably, the distribution and number of ground control points, the quality of the elevation source and the geometric sensor model or lack thereof were altered. Results were analysed through triangulating and comparing the geolocation accuracy of the ortho-images. The application of these different methods to perform orthorectification encompass the aim of this paper, which was to investigate and compare the positional accuracies of ortho-images under various orthorectification scenarios and provide improved geometric accuracies of VHR satellite imagery when diverse ground control and elevation data sources are available. By investigating the influence that the distribution and number of GCPs and the quality of DEMs have on the positional accuracy of an ortho-image, it became clear that a reasonable increase in the number of uniformly distributed GCPs combined with progressively accurate DEMs will ultimately improve the quality of the orthorectified product. The results also showed that when more GCPs were applied, the smaller the difference in accuracy was between the different DEMs utilised. It was interesting to note that when it is suitable to manually collect well-distributed GCPs using a GPS handheld device over the study area then a very accurate result can be expected. Nonetheless, it is also important to note that if it is not possible/practical to achieve the latter, satellite based GCP collection do provide a very good alternative. It was also determined that utilising GCPs which were extracted from vector road layers to only cover specific areas in the image scene produced less favourable results. Several contributions towards improved orthorectification procedures were made in this study. These include the development of an automatic GCP extraction script (A-GCP-ES), written in the Python scripting language with the purpose to ease the process of manually placing GCPs on an input image when repeatedly performing orthorectification.Thesis (PhD)--University of Pretoria, 2016.
Geography, Geoinformatics and Meteorology
PhD
Unrestricted
18
Li, Gong. "Improvement of Wind Forecasting Accuracy and its Impacts on Bidding Strategy Optimization for Wind Generation Companies." Diss., North Dakota State University, 2012. https://hdl.handle.net/10365/26815.
Full textAbstract:
One major issue of wind generation is its intermittence and uncertainty due to the highly volatile nature of wind resource, and it affects both the economy and the operation of the wind farms and the distribution networks. It is thus urgently needed to develop modeling methods for accurate and reliable forecasts on wind power generation. Meanwhile, along with the ongoing electricity market deregulation and liberalization, wind energy is expected to be directly auctioned in the wholesale market. This brings the wind generation companies another issue of particular importance, i.e., how to maximize the profits by optimizing the bids in the gradually deregulated electricity market based on the improved wind forecasts. As such, the main objective of this dissertation research is to investigate and develop reliable modeling methods for tackling the two issues.
To reach the objective, three main research tasks are identified and accomplished. Task 1 is about testing forecasting models for wind speed and power. After a thorough investigation into currently available forecasting methods, several representative models including autoregressive integrated moving average (ARIMA) and artificial neural networks (ANN) are developed for short-term wind forecasting. The forecasting performances are evaluated and compared in terms of mean absolute error (MAE), root mean square error (RMSE), and mean absolute percentage error (MAPE). The results reveal that no single model can outperform others universally. This indicates the need of generating a single robust and reliable forecast by applying a post-processing method. As such, a reliable and adaptive model for short-term forecasting the wind power is developed via adaptive Bayesian model averaging algorithms in Task 2. Experiments are performed for both long-term wind assessment and short-term wind forecasting. The results show that the proposed BMA-based model can always provide adaptive, reliable, and
iv
comparatively accurate forecast results in terms of MAE, RMSE, and MAPE. It also provides a unified approach to tackle the challenging model selection issue in wind forecasting applications. Task 3 is about developing a modeling method for optimizing the wind power bidding process in the deregulated electricity wholesale market. The optimal bids on wind power must take into account the uncertainty in wind forecasts and wind power generation. This research investigates the application of combining improved wind forecasts with agent-based models to optimize the bid and maximize the net earnings. The WSCC 9-bus 3-machine power system network and the IEEE 30-bus 9-GenCo power system network are adopted. Both single-sided and double-sided auctions are considered. The results demonstrate that improving wind forecasting accuracy helps increase the net earnings of wind generation companies, and that the implementation of agent learning algorithms further improves the earnings. The results also verify that agent-based simulation is a viable modeling tool for providing realistic insights about the complex interactions among different market participants and various market factors.
19
Kraljevic, Matija. "Character recognition in natural images : Testing the accuracy of OCR and potential improvement by image segmentation." Thesis, KTH, Skolan för datavetenskap och kommunikation (CSC), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-187991.
Full textAbstract:
In recent years, reading text from natural images has gained renewed research attention. One of the main reasons for this is the rapid growth of camera-based applications on smart phones and other portable devices. With the increasing availability of high performance, low-priced, image-capturing devices, the application of scene text recognition is rapidly expanding and becoming increasingly popular. Despite many efforts, character recognition in natural images, is still considered a challenging and unresolved problem. The difficulties stem from the fact that natural images suffer from a wide variety of obstacles such as complex backgrounds, font variation, uneven illumination, resolution problems, occlusions, perspective effects, just to mention a few. This paper aims to test the accuracy of OCR in character recognition of natural images as well as testing the possible improvement in accuracy after implementing three different segmentation methods.The results showed that the accuracy of OCR was very poor and no improvments in accuracy were found after implementing the chosen segmentation methods.
20
Dorica, Mark. "Novel mesh quality improvement systems for enhanced accuracy and efficiency of adaptive finite element electromagnetics with tetrahedra." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=80008.
Full textAbstract:
Finite element accuracy and efficiency can be directly affected by mesh quality. When employing h-adaptive solution strategies, a mesh improvement stage is required in order to ensure high quality tetrahedra. However, mesh improvement techniques and quality indicators are often based on purely geometrical considerations. Recent work has focused on theoretically linking mesh quality criteria to interpolation and discretization errors. The potential benefits and related costs of a family of new mesh quality improvement systems are investigated using a set of electromagnetic benchmarks and mesh quality measures directly associated with finite element accuracy and efficiency. The new techniques are shown to outperform the existing mesh smoothing techniques in both mesh quality improvement and computational cost. The significant gains in finite element accuracy and efficiency are highlighted through theoretical and experimental results.
21
Yan, Rong Shen. "Circuit techniques for CMOS amplifier accuracy and robustness improvement in high-side current sensing Read-out circuit." Thesis, University of Macau, 2017. http://umaclib3.umac.mo/record=b3691122.
Full text
22
Yang, Hao-Wei, and 楊皓偉. "The Application of High Accuracy Sensors on Precision Machine Tool Accuracy Improvement." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/37561462382915513474.
Full textAbstract:
碩士國立臺灣大學
機械工程學研究所
103
This research develop high accuracy multiple degrees of freedom sensors, including high resolution laser straightness measurement system and autocollimator. The sensors can detect straightness, pitch, yaw, and roll errors of the linear guideways and linear stage. By using laser expander and drift compensated system, the laser drift caused by the temperature and pressure can be reduced. The application of the digital filter can decrease the noise of the signal and improve the stability of the systems. According to the Abbe principle, the angular errors will be enlarged by the Abbe offset. The Abbe error is considered to be the major cause of volumetric error of machine tool. In the measurement system, we use the autocollimator and roll sensor to measure errors during the movement of machine tool and compensate the three angular errors immediately. Derive the volumetric error model of three-axis machine tool by homogeneous transformation matrix and compare to the volumetric error model which follow the Abbe principle. Experiment shows that the volumetric error model we proposed can significantly improve the accuracy of machine tool. Furthermore we apply the Bryan principle, the measurement axis of the straightness sensor and cutting axis cannot be coaxial. By using angular errors and Bryan offset, we can calculate the straightness error at any point in the space. Using the model we proposed to analyze and set up the error budget of a particular precision machine tool developed by the Industrial Technology Research Institute (ITRI). By using the error budget method, we can find the most cost-effective way to allocate the limit value of each geometric error of 3-axis as the guideline of installation in order to control the total volumetric errors of the machine tool. In order to achieve the target accuracy, the geometric errors of the linear stage must be decreased. The assembly error will affect the accuracy of linear guideway. The parallelism of two linear guideway will cause the pitch, yaw, and roll error. This research provides the method to adjust the linear guideway which can significantly reduce errors of the stage and achieve the target accuracy.
23
Lanza, Michele. "Improvement methods for diagnostic accuracy in ophthalmology." Rozprawa doktorska, 2018. https://repolis.bg.polsl.pl/dlibra/docmetadata?showContent=true&id=65610.
Full text
24
Wang, Han-Sen, and 王瀚森. "Improvement of visual odometry accuracy and instantaneity." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/38963526409935671706.
Full textAbstract:
碩士淡江大學
機械與機電工程學系碩士班
102
The purpose of this thesis is to improve the accuracy and instantaneity of the binocular-camera-based visual odometry (VO). The speeded-up robust features (SURF) algorithm was used to capture environment landmarks, and the perspective-3-point(P3P) algorithm and random sample consensus (RANSAC) method were used to the robot localization. The Upright-SURF, threshold of box filter, novel parametrizated P3P algorithm and randomized random sample consensus (R-RANSAC) algorithm were used to reduce computing time of the VO. The revised SURF can increase the frequency of landmark localization and then improve accuracy of the VO. The novel parametrizated P3P algorithm also improves accuracy of the VO. The improved VO was implemented on the two-wheeled mobile robot to verify accuracy and instantaneity of the VO.
25
Hsu, Jih-Sheng, and 許日昇. "Improvement in DGPS Accuracy Using Recurrent S_CMAC_GBF." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/37396085114300218770.
Full textAbstract:
碩士清雲科技大學
電機工程系所
97
This study is to design the structure of Recurrent S_CMAC_GBF use for improve in DGPS (Differential-Global Positioning System) accuracy, and to implement and test the hardware structure by using FPGA chip. This paper present the Recurrent S_CMAC_GBF in DGPS to increase for accurate positioning. We used a low cost commercial module (Trimble Lassen) to improvement the DGPS system and used the expensive commercial module (Trimble 5700) receiver to further. The proposed project is collects erroneous information and use Recurrent S_CMAC_GBF to predicted future erroneous tendency. This predicted information will be employed to improve the accuracy of DGPS. Finally, the FPGA chip is used implement Recurrent S_CMAC_GBF hardware structure, the result will be translated to computer by RS-232 to verify.
26
Lin, Chung-Jie, and 林中傑. "GPS Positioning Accuracy Improvement by Fuzzy Methods." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/04864117154083500771.
Full textAbstract:
碩士國立臺灣大學
電機工程學系
85
GPS接收機的定位精確度對於使用者而言是很重要的，特別是使用C/A 碼的單一接收機。在本論文中，將提出應用模糊理論於全球定位系統以改 善定位精確度的方法。 針對衛星幾何分佈所造成的精確釋 度(Dilution of Precision, DOP)及接收機通道之訊號雜訊比(Signal- Noise Ratio, SNR)對於定位誤差所造成的影響，於文中將有詳細的探討 。然而，PDOP和SNR之間的關係會彼此矛盾，且具有一定的模糊性，這也 就是為什麼引用模糊方法的原因。實驗的方法大致為，利用定位資料的 PDOP值、SNR值作為模糊處理單元( Fuzzy Processing Unit )的輸入，用 以推論計算該筆定位資料的信賴度因子 (Reliable Factor)。再者， 將此信賴度因子和一預先設定的臨界值比較，若信賴度因子大於該值，則 選用此定位資料。經由此方法，而可以從原始資料中，篩選出較為精確的 定位資料，達到精度改善的目的。 本實驗的方法將分別用於C/A碼單機及DGPS接收機。從實驗的結果可知， 以此方法改善GPS定位的精度，是確實可行的。而其改進之程度對C/A碼單 機是較具效果的。 The positioning accuracy of the GPS receiver is important to the users, especially for those who use the C/A code stand alone receiver. In this thesis,an application of fuzzy set theory to the problem of GPS positioning accuracyimprovement is proposed. The effects of DOP ( Dilution Of Precision ) , SNR (Signal- Noise Ratio) to positioning error are discussed in the content. However,there are tradeoffsamong the PDOP and SNR. That is the reason why we introduced these quantities into fuzzy processing unit. The PDOP and SNR values are used for the fuzzy processing unit to evaluate the reliable factor, which represents the reliability of this position fix. Next, the reliable factor is compared with adesired threshold value. If it exceeds this value, this position fix is adopted. By this way, we can select the more accurate position fixes from the original ones to improve the positioning accuracy. We employed this fuzzy processing on both the C/A code stand alone receiver and the DGPS receiver. Our experimental results will illustrate that fuzzy processing on GPS data can actually reduce the positioning error to a certain extent. The improvements on C/A code single receiver are more obvious.
27
Lin, Ting-Huei, and 林庭輝. "FEM Accuracy Improvement and Waveguide Transition Design." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/51761799883584250523.
Full textAbstract:
博士國立臺灣大學
電機工程學研究所
89
To improve the accuracy of FEM for waveguide discontinuity problems and waveguide transition design are investigated in this dissertation. The FEM method hybridizing modal expansion technique is employed to solve metallic waveguide discontinuity problems. The FEM was formulated in terms of electric or magnetic fields, called E- or H- formulations. By averaging the results obtained from E- and H-formulations with the same meshes, the accuracy improvement in the solution is analyzed. In the study, the E- and H-formulations for FEM are derived and their corresponding variational forms are described. The numerical errors of FEM using E- and H-formulation are also discussed. Some numerical results are presented to demonstrate the advantages of the finite element method by averaging the results obtained from E- and H-formulations with the same meshes. From our analysis, the accuracy of the S11 calculated with FEM can be dramatically improved for the same mode at the same port by taking the average from both E- and H-formulations with the same meshes. For scattering coefficients due to different modes or different ports, the results by dual formulations can yield a measure of the error range, but taking average does not necessarily improve the accuracy significantly. Another issue of interest in the dissertation is the transition design among waveguide and various planar transition lines. For waveguide to planar circuit transition, a new transition mechanism is proposed. The transition mechanism is based on the concept of tapered slot antenna and E-plane probe coupling. The design of the proposed transition mechanism is investigated in detail. Parameters of the new tapered slot probe are studied by numerical simulation. The newly developed tapered CPS probe is applied to different planar circuit to waveguide transition design, including slotline-to-waveguide, microstrip-to- waveguide and CPW-to-waveguide. The method and procedure to design the transitions are investigated. The X-band and Ka-band transition design is demonstrated by numerical simulation and some transitions have also been fabricated and verified by measurement results. The characteristics of the transitions exhibit advantages of broad bandwidth, compact size, easy integration, low fabrication cost, and high reliability. Finally, a new broadband microstrip-to-CPW transition based on microstrip electrical field and CPW magnetic field resonant coupling is proposed. The design procedure is investigated in detail and the equivalent circuit model is also described. The C-band and Ka-band transition are designed by numerical simulation and the C-band transition is also verified by measurement result. The features of this transitions are broad bandwidth, easy fabrication and no via or bonded-wire. The features will provide the transition a wide range of application in MIC/MMIC circuits.
28
Lanza, Michele. "Improvement methods for diagnostic accuracy in ophthalmology." Rozprawa doktorska, 2018. https://delibra.bg.polsl.pl/dlibra/docmetadata?showContent=true&id=47074.
Full text
29
Lanza, Michele. "Improvement methods for diagnostic accuracy in ophthalmology." Rozprawa doktorska, 2018. https://repolis.bg.polsl.pl/dlibra/docmetadata?showContent=true&id=47074.
Full text
30
Lanza, Michele. "Improvement methods for diagnostic accuracy in ophthalmology." Rozprawa doktorska, 2018. https://delibra.bg.polsl.pl/dlibra/docmetadata?showContent=true&id=65610.
Full text
31
Tang, Y., Han Tong Loh, J. Y. H. Fuh, Yeow Sheong Wong, L. Lu, Y. Ning, and X. Wang. "Accuracy Analysis and Improvement for Direct Laser Sintering." 2003. http://hdl.handle.net/1721.1/3898.
Full textAbstract:
The accuracy issue of a rapid prototyping-direct laser sintering system is studied in this paper. The sources of errors are analyzed for their contribution to the final accuracy of built parts. The error sources are related to the hardware and software of the machine, the materials and the process. Special measures were exploited to improve the accuracy of the direct laser sintering system and process. For the errors caused by hardware like laser scanner, compensation by software was developed to correct the errors resulting from galvano-mirrors and F-θ lens. A compensation function mode was added to the slicing software to compensate the errors caused by material shrinkage and laser beam offset. Based on the analysis and improvement, a desired accuracy of 0.2mm has been achieved for the direct laser sintering system, which was verified by experiments.Singapore-MIT Alliance (SMA)
32
Shih, Naishuo, and 石乃碩. "Accuracy Improvement of License Plate Tracking and Recognition." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/01475805313044474609.
Full textAbstract:
碩士大葉大學
資訊管理學系碩士班
100
As economic activity to flourish and traffic's complete, people have more car than before. Therefore, traffic management becomes more important. In before, traffic monitoring was using people watching video. It is very waste time and human. So our proposed a new approach to improve this status. Our tracking and recognition license plate using the sequential video images. First, our using background subtraction to detection foreground objects. Second, our using Sobel edge detection to finding foreground objects edge. Finally, using Hough transform to location the license plate. After license plate location, our extract features for tracking. Our tracking’s approach is using the license plates locations range extend double to finding license plate location in the next image. By using this approach we can get the license plates moving direction. Another, we propose an approach of license plate recognition. Our propose a specific character set recognitions core join to the recognition system, and we also propose a specific strings search mechanism for license plates search. Our using by those, specific character set recognitions core and specific strings search mechanism, to improvement license plates recognition accuracy and its search speed.
33
Wu, Kuo-Hwa, and 吳國華. "GPS Accuracy Improvement with Satellite In-view VisualDetection." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/99500953279952419631.
Full textAbstract:
碩士國立臺灣科技大學
電子工程系
103
As GPS technology becomes more popular, its application becomes widely adapted in products across the market. GPS technology can be found in products such as automobile navigation systems, smart phones, wearable devices, and geographical surveying equipment. Among these, automobile navigation systems are the most widely known, with widespread commercial successes. As automobile navigation systems are primarily used in highly urbanized areas, high-rises will inevitably disrupt GPS signal acquisitions due to obstruction of satellites or will cause multipath effect phenomenon when signals are reflected from the surfaces of surrounding buildings. Hence, inaccurate positioning will be generated by GPS receivers. We suppose GPS receiver get satellites information(Elevation、Azimuth、C/No) and a coordinate of latitude & longitude to indicate user’s current position, along with current level of multipath effect, therefore we can make an inference the multipath pseudorange error from positioning calculation. This study used a fisheye camera mounted atop a vehicle to capture 360° aerial views of the sky via the binary image thresholding technique to identify boundaries of the sky with direct line-of-sight coverage. By incorporating NMEA data, the GPS receiver acquired the satellite aerial position, identified those that were obscured, and evaluated how surrounding buildings were contributing to the multipath effect. Because current position errors in GPS receiver could be preliminarily determined,multipath pseudorange error caused by surrounding interference effect was estimated. REVERSE DGPS algorithm was then applied to correct errors in pseudorange differences. Next, position deviations in direction and distance were calculated to obtain a more accurate position. This study aims to provide a method to help a vehicle adhere to its proper course when navigating through areas with obstructed satellite signals and multipath effect that may potentially deviate the vehicle from its desired route. The experimental results show that GPS positioning errors can indeed be reduced using this technique.
34
WU, YI-TSENG, and 吳奕增. "Accuracy Evaluation and Improvement of a Delta Robot." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/5p85s6.
Full textAbstract:
碩士明志科技大學
機械工程系機械與機電工程碩士班
107
Compared with the serial robot, delta robot has higher moving speed and better positioning accuracy. That is why delta robot used for pick and place and 3D printing. Previous research about delta robot are formula derivation and software simulation. There is no measurement research. Therefore, this study is based on previous research and laboratory-made delta robot. Check the kinematics with MATLAB, control the DC motor with Arduino, and using measuring instrument to evaluated accuracy and find the factors affecting the accuracy are identified for improvement. In this study, the position repetition accuracy of delta robot with spring is improved by 80% compared to a delta robot with no spring through the measurement results of Coordinate Measuring Machine, and judging whether the motor is working properly by the count value of encoder feedback. Laser tracker is used to measure the optimal working height of delta robot.
35
Ho, Hui-Chun, and 何慧君. "Improvement of Indexing Accuracy forGloboidal Cam Indexing Mechanisms." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/49190156036820219977.
Full textAbstract:
博士國立中山大學
機械與機電工程學系研究所
91
Globoidal cam indexing mechanism (GCIM) plays an important role in automation and machining tools. With the compact structure, a GCIM is able to reach the required precision on account of high stiffness and minimized backlash. The requirement to improve the indexing accuracy for GCIMs from industry applications drives the research going on. In this dissertation, two strategies to improve the indexing accuracy of GCIMs are proposed. The first strategy is by considering the manufacturing parameters involved in the processes of machining and assembly. Analytical expressions for the turret motion and indexing accuracy of grooved GCIMs have been identified. Based on the kinematic and geometric relationships between the cam and its roller-follower turret, the effects on the output of the cam mechanism due to clearances (between the cam and roller; in the roller bearing), preload (change of the distance between input and output shafts), and the cam taper angle have been investigated. As a result, the roller alternation in the cam-turret system can be analyzed. Favorable parameters for the design, machining, and assembly can be selected to manufacture such devices with improved turret motion and indexing accuracy. Worked examples are given to demonstrate the applications of the approach. The second strategy is a technique for designing torque balancing cam (TBC) systems that are composed of spring-loaded planar cams with translating followers for GCIMs. Such a device can be attached to the input shaft of a GCIM to reduce the variation of its cam rotational speed. As a result, for high-speed applications, the intensity of residual vibrations of a GCIM can be decreased and its indexing accuracy can be improved. To approximate the required counterbalancing torque curves, nonparametric rational B-splines have been applied to synthesize the planar cam motion programs. Experimental results have also been shown in a practical and high-speed application to prove such a TBC mechanism is useful and effective.
36
Yang, Chung Shun, and 楊中舜. "Kalman Filter for the Improvement of GPS Positioning Accuracy." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/75215051063814308180.
Full textAbstract:
碩士國立海洋大學
電機工程學系
85
Global Positioning System (GPS) has become the leader of modern electronic navigation systems due to its properties of high accuracy and multi-purpose.However, the GPS is also a physical system, so the positioning accuracy willdecrease because of the disturbance error source. From relevant literature, Kalman Filter, which is a multi-input/multi- outputsystem, can be successfully applied to GPS. Kalman Filter can not only computethe position and clock statesof the receiver simultaneously, but also its recursive form can easily be realized to avoid the increase of computation load.Besides, we can make use of the "off-line analysis process" to evaluate the positioning accuracy and the process models of Kalman Filter before the posi- tioning estimation starts. When we estimate the states of a dynamic receiver, it is often to describe the dynamics of the receiver with a process model called "Position- Velocity model"or "PV model". But it is inadquate to describe the high dynamics receiver with PV model because velocity changes rapidly in a short time interval. The purposeof this thesis is to describe the high dynamics receiver with anoyher processmodel called "Position-Velocity-Acceleration model" or "PVA model" used in Kalman Filter for improveing the positioning accuracy. Prediction results from off-line error analysis show that the ability of PVA model to improve the GDOPChimney due to bad observation conditions is better than PV model. Simulation results also show that PVA model can better describe the dynamics of a high dynamic receiver, as a result, wether the observation conditions is, the posi-tioning accuracy of PVA model is always better than PV model.
37
Chiuo, Ming-Da, and 邱銘達. "Accuracy improvement on the directional buoy measuerment and analysis." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/81015167395554872251.
Full textAbstract:
碩士國立成功大學
水利及海洋工程學系
89
Data buoy, which features comparatively reliability and robustness, is the most frequent applied alternatives on the measurement of oceanographical data. The wave directional spectra can be obtained by analyzing the observed heave, pitch and roll motion of the buoy hull. The accurate determination of the directional spectra serves as a diagnostic tool for the quantification of key mechanisms governing the dynamics of ocean waves. The objective of present study is to improve the accuracy of directional spectra measurement and analysis. New algorithms are intended to be developed instead of modifying current hardware design and mooring structure. The low frequency noise contaminant, which can be magnified due to the linear conversion from the acceleration spectrum to the displacement spectrum, is the major cause of the inaccuracy. This kind of error leads to mistakenly estimate the significant wave heights and periods. To reduce the error, a correction function to eliminate low-frequency noise is developed based on the previous Lang’s theory. The present method is then proven by numerical simulations and field data analysis to be capable of eliminating the noise. Moreover, the parameters, which should be determined depending on the sea state, is unified to single one in present method. This contributes to improve its applicability of routine analysis. Concerning to wave directionality analysis, the asymmetric response of amplitudes and phase differences of buoy hull to the waves are the major sources of inaccuracy. This asymmetric response comes from the combined mooring and wind-current effect. On the other hand, the instrumentation of slope measurement will affect the estimation of directional spreading as well. Bi-accelerometers or Gyroscopes, which are available from sensing industry, are widely utilized in the data buoy as inclinometers. However, both the mentioned instrumentations will be effected by the combinations of the two physical mechanisms: the centripetal acceleration from the orbital motion of wave particles and the real inclinations on the wave surface. These two forces apply on the inclinometers with opposite directions and nearly the same order of magnitude and will result in the slope measurement incorrect thus lead to misestimate the main direction and over-estimate the directional spreading. In order to improve the accuracy of directional spreading estimation, Steele's theory was modified and adopted in present study. The newly proposed method was then validated by numerical simulations. Finally, the results demonstrate that the differences of the main direction between the target and the output range from 0 to 20 degree when applying the method to the field wave data.
38
HUANG, HSIU-LING, and 黃綉玲. "Accuracy Improvement of 5G Channel Measurements with Genetic Algorithms." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/v784fm.
Full textAbstract:
碩士國立中正大學
通訊工程研究所
105
The millimeter-wave frequency band has been considered as one of the key components for next generation (5G) mobile cellular communications. While these high frequency bands offer vast swaths of underutilized spectrum, the propagation channel characterization needs to be thoroughly scrutinized prior to system design at these bands. In this thesis, channel measurement is conducted by using an omni-directional antenna at transmitter and a directional horn antenna at receiver to help improve the range of measurements. With transmission of pseudo noise (PN) sequence, the cross-correlation is performed to acquire the multipath delays at receiver. Unlike the low frequency bands, the antenna configuration used for measurements above 6 GHz is actually not the same as used for the operating equipment. The measurements are the result of the convolution of the measurement radiation patterns and the propaga-tion channel. Thus reconstructing the true channel model needs to devise an effective algorithm to decouple the measurements from the measurement radiation patterns. In this thesis, the path delays are known in advance by PN-code sounding and the genetic algorithm (GA) is utilized to extract the channel characteristics in direction of arrival and received path power for the multipath components. We propose a simple method to find a good initial population for the GA algorithm. Numerical results show that the GA algorithm with the proposed initial popula-tion can greatly improve the accuracy of 5G channel measurements in comparison with that with random initial population. Moreover, the proposed GA can accurately estimate the channel characteristics even for large measurement angle and 3-dB beamwidth of horn antenna, which can significantly reduce the time consumption of channel measurement and enable the use of smaller size horn antenna, respectively.
39
"Accuracy improvement in XPS by low energy argon ion." 2004. http://library.cuhk.edu.hk/record=b5891899.
Full textAbstract:
Tam Yi Mei.Thesis (M.Phil.)--Chinese University of Hong Kong, 2004.
Includes bibliographical references.
Abstracts in English and Chinese.
Abstract --- p.ii
摘要 --- p.iii
Acknowledgement --- p.iv
Table of Contents --- p.v
List of Figures --- p.ix
List of Tables --- p.xii
Chapter Chapter 1 --- Background of study --- p.1
Chapter 1.1 --- Introduction --- p.1
Chapter 1.2 --- Theoretical background of XPS --- p.2
Chapter 1.2.1 --- Principle of XPS --- p.2
Chapter 1.2.2 --- Surface sensitivity --- p.6
Chapter 1.2.3 --- Inelastic Mean Free Path (IMFP) --- p.6
Chapter 1.3 --- XPS spectral features --- p.7
Chapter 1.3.1 --- Chemical shift --- p.8
Chapter 1.3.2 --- Spin orbital splitting (SOS) --- p.8
Chapter 1.4 --- Quantitative analysis in XPS --- p.10
Chapter 1.4.1 --- Atomic concentration --- p.10
Chapter 1.4.2 --- Layer thickness determination --- p.11
Chapter 1.5 --- The new XPS analysis technique in the present study --- p.14
Chapter 1.5.1 --- Ion sputtering --- p.14
Chapter 1.5.1.1 --- Sputtering-induced defects --- p.16
Chapter 1.5.1.2 --- Effects of ion incident angle --- p.17
Chapter 1.5.1.3 --- Depth resolution --- p.17
Chapter 1.5.2 --- Perpendicular detection --- p.19
Chapter 1.6 --- Objectives of present study --- p.23
References for Chapter1 --- p.24
Chapter Chapter 2 --- Instrumentation --- p.28
Chapter 2.1 --- Introduction --- p.28
Chapter 2.2 --- X-ray Photoelectron Spectroscopy --- p.28
Chapter 2.2.1 --- XPS used in the present study --- p.28
Chapter 2.2.2 --- Vacuum requirements --- p.29
Chapter 2.2.3 --- X-ray source --- p.29
Chapter 2.2.4 --- Charge Neutralizer --- p.33
Chapter 2.2.5 --- Ion sputtering gun --- p.34
Chapter 2.2.6 --- Electron energy analyzer --- p.36
Chapter 2.2.6.1 --- Energy resolution --- p.38
Chapter 2.2.6.2 --- Pass energy --- p.38
Chapter 2.2.7 --- Electron detector / Multiplier --- p.39
Chapter 2.3 --- Other analysis techniques for verification --- p.42
Chapter 2.3.1 --- Energy Dispersive X-ray detector in Scanning Electron Microscope (SEM-EDX) --- p.42
Chapter 2.3.2 --- X-ray Fluorescence Spectrometer (XRF) --- p.42
Chapter 2.3.3 --- Rutherford Backscattering Spectrometer (RBS) --- p.43
Chapter 2.3.4 --- Differential Scanning Calorimeter (DSC) --- p.44
References for Chapter2 --- p.45
Chapter Chapter 3 --- Determination of the thickness of the damaged layer --- p.46
Chapter 3.1 --- Introduction --- p.46
Chapter 3.2 --- Experimentation --- p.46
Chapter 3.2.1 --- Instrumentation --- p.46
Chapter 3.2.1.1 --- Work function calibration --- p.48
Chapter 3.2.1.2 --- Sputtering ion beam calibration --- p.49
Chapter 3.2.2 --- Sample preparation --- p.49
Chapter 3.2.3 --- XPS measurements --- p.51
Chapter 3.3 --- Results and discussion --- p.53
Chapter 3.3.1 --- Spectral analysis and peak fitting --- p.53
Chapter 3.3.2 --- Modeling and damaged layer thickness determination --- p.59
Chapter 3.3.3 --- TRIM simulation --- p.62
Chapter 3.4 --- Conclusion --- p.65
References for Chapter3 --- p.68
Chapter Chapter 4 --- Applications of the new XPS technique to different materials --- p.70
Chapter 4.1 --- Introduction --- p.70
Chapter 4.2 --- Analysis of ceramic --- p.70
Chapter 4.2.1 --- Experimentation --- p.71
Chapter 4.2.2 --- XPS results and comparison with other analysis techniques --- p.74
Chapter 4.3 --- Analysis of metal alloys --- p.77
Chapter 4.3.1 --- Experimentation for the tin-lead solder bump analysis --- p.78
Chapter 4.3.2 --- Calibration of XPS sensitivity --- p.78
Chapter 4.4 --- Development of XPS analysis method for the tin-silver solder bump measurement --- p.82
Chapter 4.4.1 --- Experimentation --- p.83
Chapter 4.4.2 --- XPS results --- p.83
Chapter 4.5 --- Analysis of polymer (Polyacrylic acid) --- p.84
Chapter 4.5.1 --- XPS results --- p.84
Chapter 4.6 --- Analysis of Indium Phosphide --- p.90
Chapter 4.6.1 --- XPS results --- p.92
Chapter 4.7 --- Analysis of Gallium Arsenide --- p.96
Chapter 4.8 --- Conclusion --- p.100
References for Chapter4 --- p.101
Chapter Chapter 5 --- Conclusions --- p.102
40
Chang, Chia-Hung, and 張嘉宏. "Accuracy Improvement for RNA Secondary Structure Prediction with SVM." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/gf7ax2.
Full textAbstract:
碩士國立中山大學
資訊工程學系研究所
96
Ribonucleic acid (RNA) sometimes occurs in a complex structure called pseudoknots. Prediction of RNA secondary structures has drawn much attention from both biologists and computer scientists. Consequently, many useful tools have been developed for RNA secondary structure prediction, with or without pseudoknots. These tools have their individual strength and weakness. As a result, we propose a hybrid feature extraction method which integrates two prediction tools pknotsRG and NUPACK with a support vector machine (SVM). We first extract some useful features from the target RNA sequence, and then decide its prediction tool preference with SVM classification. Our test data set contains 723 RNA sequences, where 202 pseudoknotted RNA sequences are obtained from PseudoBase, and 521 nested RNA sequences are obtained from RNA SSTRAND. Experimental results show that our method improves not only the overall accuracy but also the sensitivity and the selectivity of the target sequences. Our method serves as a preprocessing process in analyzing RNA sequences before employing the RNA secondary structure prediction tools. The ability to combine the existing methods and make the prediction tools more accurate is our main contribution.
41
Huang, Hsin Hung, and 黃信紘. "The Process improvement and accuracy analysis of Ceramic Laser Fusion." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/98611488392252016455.
Full text
42
Huang, Shih-Yu, and 黃仕宇. "Improvement of Machining Accuracy at Corner Parts for Wire-EDM." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/84436035780014677823.
Full textAbstract:
碩士國立交通大學
控制工程系
85
Manufacturing industry of nowadays follows a trend towards high precision machining. Wire electrical discharge machining (Wire-EDM) has almost occupied an important position in some production fields, due to its capability of machining hard materials and intricate shapes. However, the machining accuracy, especially at corner parts, may be destroyed because of some phenomena such as wire deflection and vibration, etc. The purpose of this thesis is to develop a control strategy so that the machining accuracy at corner parts for wire-EDM can be improved. Because of the use of low-rigidity wire electrodes, it is essential to understand the behavior of wire electrodes in machining process. The main causes of inaccuracies due to wire- EDM process at corner parts are illustrated. In order to maintain machining quality at corners, a control strategy based on fuzzy logic is proposed. The fuzzy rules based on the wire- EDM's physical characteristics, experimental data, and operator' s experience are constructed, so that the reduced percentage of sparking force can be determined by a multi-variables fuzzy logic controller. Sparking force is modified by means of regulating the machining coefficient, OFF-TIME. Thechange of the OFF-TIME of the discharging pulse can not only achieve the above aim but also have a little influence in the machining process. The objective of the total control is to improve the machining accuracy at corner parts, but still keep the cutting feedrate at fair values. In this thesis, the main phenomena thought to be predominantly related to inaccuracies at corners can be improved by the proposed control strategy. As a result of experiments, machining errors of corner parts, especially in rough-cutting, can be reduced to less than 50% of those in normalmachining, while the machining process time increases not more than 10% of the normal value.
43
Chen, Guan-Ru, and 陳冠儒. "Accuracy Improvement of Closed-Form TDOA LocationMethods Using IMM Algorithm." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/98899202417333178099.
Full textAbstract:
碩士國立中山大學
電機工程學系研究所
98
For target location and tracking in wireless communication systems, mobile target positioning and tracking play an important role. Since multi-sensor system can be used as an efficient solution to target positioning process, more accurate target location estimation and tracking results can be obtained. However, both the deployment of designed multi-sensor and location algorithm may affect the overall performance of position location. In this thesis, based on the time difference of arrival (TDOA), two closed-form least-square location methods, spherical-interpolation (SI) method and spherical-intersection (SX) method are used to estimate the target location. The two location methods are different from the usual process of iterative and nonlinear minimization. The locations of the target and the designed multiple sensors may yield geometric effects on location performance. The constraints and performance of the two location methods will first be introduced. To achieve real-time target tracking, the Kalman filtering structures are used to combine the SI and SX methods. Because these two positioning and tracking systems have different and complementary performance inside and outside the multi-sensor array, we consider using data fusion to improve location estimation results by using interacting multiple model (IMM) based estimator, in which internal filters running in parallel are designed as the SX-KF1 and the SI-KF2. However, due to the time-varying characteristics of measurement noises, we propose an adjusting scheme for measurement noise variance assignment in the Kalman filters to obtain improved location estimation results. Simulation results are obtained by running Matlab program. In three-dimensional multi-sensor array scenarios, the results of moving target location estimation shows that the IMM-based estimators effectively improve the position performance.
44
沈昱勝. "A Strategy for Improvement of Doppler Estimates and Navigation Accuracy." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/48442889735672320230.
Full textAbstract:
碩士國立臺灣海洋大學
通訊與導航工程學系
99
The paper by Kalman algorithm combines with design of ultra-tight integration navigation. Ultra-tight integration, also known as deep integration, has superb complementary nature between GPS and INS when front-end receiver receives I.Q. signals for real-time tracking. And velocity complementary is used to estimate the drift rate of auxiliary carrier Doppler ultra-tight structure, so as to enhance the performance of loop tracking. The structure of Doppler ultra-tight compensated integration provides more accurate concept of drifting rate which is resulted from Doppler. Increasing frequency and phase lock loop are applied to the filter to enhance the internal structure of multi-path interference and high dynamic capabilities and performance when to strengthen the weak signal tracking capability, improve the urban or indoor positioning accuracy. The feature of Interacting Multiple-model can be fully applied to the system which contains uncertainties, even to distinguish the position when in high dynamics; by the characteristics of Interacting Multiple-model algorithm to support ultra-tight EKF UKF, so that positioning is more flexibility and to enhance the accuracy of system.
45
Wang, Yang-Chang, and 王永川. "A study of accuracy improvement about carrier phase under DGPS." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/61223797902415950320.
Full textAbstract:
碩士國立海洋大學
航海技術學系
83
We edited programs to improve single position accuracy with carrier phase under DGPS. We use the skills of the kinematic survay to combined carrier phase and code to get a instantly accuracy position. Then use the 「 ambiguity function method 」 to find the cycle ambiguity. Afterward, we can use carrier phase to position and survey the cycle slip by accumulating the Doppler shift of the satellite signal. The result of static position test after phase smooth under SDGPS ( STDE: 0.8402, VAR: 0.7059 ) better than DGPS ( STDE: 0.8492, VAR: 0.7212 ), and little difference betwen DGPSand SDGPS in kinematic test. Beside, the single ambiguity function method ,which the style of error is same with C/A code position and which has not good accuracy.
46
Li, Chi-Han, and 李紀漢. "Accuracy Improvement on Cash Flow Forecasting Model on Architectural Engineering." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/26317868118081075026.
Full textAbstract:
碩士逢甲大學
土木工程所
94
Sales, field administration and finance are the key to operation management of construction companies, also the essentiality to survival of construction contractors. Finance management back-ups sales and field administration, and cash-flow among finance management as important as keeping blood flowing in human bodies. The major profit comes from getting engineer projects, the finance management of each engineering project needs to probe into operation flow and finance management of every bid, operation and even final in order to consolidating and modifying an achievable cash-flow forecast model, to assist contractor in having stable growth and profit through security control and elastic cash-flow performance. Construction workers mostly come from professional schools, in general, they lack of finance background and cash-flow thinking. The purpose of cash-flow forecast is to provide operators to understand if income and expense achieve balance in each project period, for the purpose of organizing all building engineer, predicting finance balance, and preventing to happen fund shortage. On the other hand, the passive function is to offer executive to overview current funds and active capital in advance, and the active function is to build a health financial structure, adjust directions and acting conditions of receiving cases.
47
Su-WeiLin and 林舒葦. "Accuracy Improvement of Terrestrial Mobile Mapping Systems Using Triangulation Adjustment." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/s6nu5v.
Full textAbstract:
碩士國立成功大學
測量及空間資訊學系
105
Traditionally, aerial Photogrammetry is used to do large area measurements by aerial images. However, taking images from an airplane can be so easily affected by weather that the time limitation related to taking images is very serious, and aerial Photogrammetry is also expensive. The other problem by Photogrammetry is the lack of façades of houses. Therefore, to overcome these problems, Mobile Mapping Systems (MMS) have been developed. In this article, a terrestrial MMS is used for the research. If a terrestrial MMS combines GPSs and an IMU, it can perform direct geo-referencing and then a forward intersection to determine many ground coordinates of points. However, the accuracy of results using terrestrial MMS is not stable or reliable, and thus this approach may be worse than using aerial Photogrammetry. This research introduces exterior orientation obtained from a terrestrial MMS with the help of ground control points introduced into bundle block adjustment in order to improve the positioning accuracy. The positioning accuracy will be significantly improved when we set a pair of ground control points every 60m. Using an exterior orientation from a terrestrial MMS with a pair of ground control points placed every 60m and using bundle block adjustment can raise the accuracy from 2232cm to 15cm.
48
CUC, LE THI, and 黎氏菊. "The improvement of the accuracy of the PM2.5 sampling system." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/43t3d8.
Full textAbstract:
博士國立交通大學
環境工程系所
107
PM2.5 air quality standard was promulgated in many countries to protect public health since epidemiology studies have found association between particles with aerodynamic diameter <2.5 µm (PM2.5) and increased mortality, both daily and over time. FRM (Federal Reference Method) PM2.5 samplers and FEM (Federal Equivalent Method) monitors are mainly used as compliance monitors, which make use of size-selective inlets followed by a filter to collect particles for further analysis. The PM2.5 size-selective inlets which are WINS (Well Impactor Ninety-Six) or PM2.5 VSCC (Very Sharp-cut Cyclone) inlets play an important role in the sampling accuracy of the sampling systems. However, the field test of the WINS without regular replacement of the well shows the decrease in the cutoff diameter (dpa50) down to 2.12 µm and the increase in the negative sampling bias to 20% after 17 continuous sampling days. It is due to particles pile up the mound on the substrate, resulting in the particle loading effect. The performance of the uncleaned PM2.5 VSCC is claimed not to be affected by the particle loading effect. However, when the sampling period is over 6 days, we found fluctuations in measured PM2.5 concentrations as compared to the concentrations of the VSCC which is cleaned daily. In this study, a modified WINS (M-WINS) were developed to eliminate the particle bounce and overloading effects for unattended operation over a long sampling period. The M-WINS¬1 which uses water to wash the wetted glass fiber filter substrate (GFFS) clean continuously to eliminate the particle overloading effect and extend the service life of the impactor without the need of impaction well cleaning and replacement of the oil-soaked GFF. The laboratory test shows that dpa50 of the M-WINS1 only varies slightly from 2.44 to 2.49 µm when the loaded particle mass increases from 0–6 mg. The field test shows that dpa50 and the sampling bias of the M-WINS1 meet the USEPA requirements (dpa50 = 2.5 ± 0.2 µm and sampling bias < ±5%) after 17 continuous sampling days. Instead of using continuous water flow, the M-WINS2 uses vacuum oil which is injected periodically to wash off the deposited particles. The laboratory test results show that the M-WINS2 has a similar cut-size (2.43 ± 0.02 µm) and sharpness (1.22) as the WINS. Without cleaning the substrate, the particle loading test at the laboratory for M-WINS2 shows that the cut-size decreases from 2.49 to 2.18 µm as the particle mass loading increases from 0 to 3.5 mg with a particle mound formed on the substrate. The cut-size of M-WINS2 is able to recover to 2.46 µm when the oil flow is injected for just 1-min at the flow rate of 3 mL min-1 to wash off the mound. This saves oil consumption. Therefore, the current M-WINS can be used as the PM2.5 size-selective inlet for unattended, continuous sampling for a long time with a very good sampling accuracy. In addition, the liquid sample collected from the M-WINS¬1 can be analyzed for measurement of the water-soluble ions (WSI) in deposited particles. In order to determine the accurate ion concentration of WSIs, the particle loss in the inlet tube of the M-WINS1 was studied. The results show that the particle loss in the inlet and outlet tubes of the M-WINS1 increases from 0 to 77% for oleic acid (OA) particles and 0 to 67% for ammonium fluorescein (AF) particles when the particle sizes are increased from 2.3-10.3 µm. Particle loss is severe for large particles since the original inlet tube (inner diameter = 28.4 mm) have two sharp-edged contractions (28.4 to 12.7 mm, then 12.7 to 3.91 mm) before the nozzle of 3.91 mm in diameter, large particles deposit on the contractions and inner walls due to inertial impaction and interception. A new inlet tube was made by smoothing the sharp edges to eliminate the particle loss. The results show that the particle loss is reduced from <11.8% to <4.3% for dpa less than 4 µm, <33.4% to <21.5% for dpa less than 5.8 µm and <68.2% to <49.9% for dpa less than 10.3 µm. The total estimated particle loss in coarse particles in the M-WINS is reduced from 28.7 ± 11% for the original inlet tube to 19.5 ± 7% for the new inlet tube, which is reasonably small enough for correcting the measured ion concentrations in coarse particles. Therefore, the new PM2.5 inlet developed in this study is useful for future automatic monitoring of ion concentrations in coarse particles.
49
FU, CHIA-KUO, and 傅嘉國. "The Study of Improvement GPS Accuracy in Multiple User Modes." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/pha5a7.
Full textAbstract:
碩士淡江大學
電機工程學系碩士在職專班
106
Before measuring geographies, buildings, mapping maps and communications, must be used to measure the GPS coordinates. In order to reduce the number of tester and the time for measurement and comparison, we are to design an industrial tablet to find suitable locations, control instruments, collect data, combine drawing software and communicate in face time. So we must first set the accuracy and use in different windows working modes. Debug and find the solution of fail modes after accuracy test with different working modes. Last compare accuracy to another brand industrial tablet in different working modes.
50
CAI, JHENG-JHE, and 蔡正哲. "Accuracy improvement of image database positioning by using smart phone." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/20837220759333644575.
Full textAbstract:
碩士國立臺灣科技大學
機械工程系
102
Currently positioning mobile phone is using GPS but it always be affected by environmental factors which end up positioning error. In this thesis our main research directions is by using the images to assist mobile phone positioning. In the case of building an image database, use shooting image and the information on mobile phone sensor to achieve high precision positioning. The thesis is divided into three major structures, mainly is building an image database to search images then use the same feature points and the forward intersection method to locate, effectively improve the positioning accuracy. Establishing Image Database: Using a mobile phone camera and e-compass to build an image Database. It contains the coordinates and angles of the images. Image searching and matching: Using the image and the angle of image to match and search images from an image database, using the image processing SURF algorithms to search the similar images. Self-Positioning: Using SIFT algorithm to search the same feature points from two similar images with shooting image and calculate angle of feature points and use the forward intersection method to locate two feature point coordinates. Utilizing other similar images to correct feature points coordinates, and use the correct feature points coordinate to locate shooting image coordinate.