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Link Adaptation in 5G Networks : Reinforcement Learning Framework based Approach / Länkanpassning i 5G-nätverk : Förstärkning Lärande rambaserat tillvägagångssättSatya Sri Ganesh Seeram, Siva January 2022 (has links)
Link Adaptation is a core feature introduced in gNodeB (gNB) for Adaptive Modulation and Coding (AMC) scheme in new generation cellular networks. The main purpose of this is to correct the estimated Signal-to-Interference-plus-Noise ratio (SINR) at gNB and select the appropriate Modulation and Coding Scheme (MCS) so the User Equipment (UE) can decode the data successfully. Link adaptation is necessary for mobile communications because of the diverse wireless conditions of the channel due to mobility of users, interference, fading and shadowing effects, the estimated SINR will always be different from the actual value. The traditional link adaptation schemes like Outer Loop Link Adaptation (OLLA) improve the channel estimation by correcting the estimated SINR with some correction factor dependent on the Block Error Rate (BLER) target. But this scheme has a low convergence i.e., it takes several Transmission Time Intervals (TTIs) to adjust to the channel variations. Reinforcement Learning (RL) based framework is proposed to deal with this problem. Deep Deterministic Policy Gradient (DDPG) algorithm is selected as an agent and trained with several states of the channel variations to adapt to the changes. The trained model seems to show an increase in throughput for cell edge users of about 6-18% when compared to other baseline models. The mid-cell user throughput is increased up to 1-3%. This RL model trained is constrained with average BLER minimization and throughput maximization which makes the model perform well in different radio conditions. / Länkanpassning är en kärnfunktion som introduceras i gNB för adaptiv modulering och kodningsschema (AMC) i den nya generationens cellulära nätverk. Den huvudsakliga syftet med detta är att korrigera det uppskattade signal-till-störning-plus-bruset ratio (SINR) vid gNodeB (gNB) och välj lämplig Modulation och Coding Scheme (MCS) så att användarutrustningen (UE) kan avkoda data framgångsrikt. Länkanpassning är nödvändig för mobil kommunikation eftersom av de olika trådlösa förhållandena för kanalen på grund av användarnas mobilitet, störnings-, bleknings- och skuggeffekter, kommer den uppskattade SINR alltid skiljer sig från det faktiska värdet. De traditionella länkanpassningssystemen som Outer Loop Link Adaptation (OLLA) förbättra kanaluppskattningen med korrigera det uppskattade SINR med någon korrigeringsfaktor beroende på Mål för Block Error Rate (BLER). Men detta system har en låg konvergens det är det krävs flera TTI för att anpassa sig till kanalvariationerna. Förstärkning Ett lärande (RL)-baserat ramverk föreslås för att hantera detta problem. Djup Deterministic Policy Gradient (DDPG) algoritm väljs som en agent och tränas med flera tillstånd av kanalvariationerna för att anpassa sig till förändringarna. Den tränade modellen verkar visa en ökning i genomströmning för cellkantanvändare på cirka 6-18% jämfört med andra basmodeller. Mittcellsanvändaren genomströmningen ökas upp till 1-3%. Denna RL-modell utbildad är begränsad med genomsnittlig BLER-minimering och genomströmningsmaximering vilket gör modell fungerar bra i olika radioförhållanden.
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台灣不良債權市場之探討劉宏麟 Unknown Date (has links)
台灣政府為推動金融自由化,於1991年開放民營銀行之設立,另輔導信用投資公司及信用合作社轉制為商業銀行,公營銀行釋股轉為民營銀行,期待台灣金融業與國際接軌,提高全球的競爭力。因短時間內大量銀行的設立,相互競爭激烈,導致獲利下降,而競爭衍生不當放款,及財團惡意掏空銀行,種下未來之惡果,銀行逾期放款大幅增加,資本適足率不足,政府提出金融改革,展開台灣不良債權市場新的一頁。
台灣不良債權市場自2001年開始至今已邁入第13年,共出售新台幣1兆5,513億元,而不良債權市場高峰於2002年有2,500億,到2013年僅有新台幣93億,何種原因造成市場萎縮,經本研究蒐集彙整不良債權發展過程、相關資訊及法規,從不良債權相關法令與管制、金融機構授信品質提高及台灣經濟景氣與不動產景氣趨勢三項來探討,驗證不良債權市場的波動與金融機構授信品質及台灣總體經濟與不動產景氣呈反向關係,是造成台灣不良債權市場改變之原因,而相關法令之制訂與修改,促使不良債權市場成為健全台灣金融體系重要的一環。
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Framtida installationskrav på Electronic Flight Bags (EFB) : Med hänsyn till litiumbatterier / Future regulations for the installation of Electronic Flight Bags (EFB)Al Hamrani, Emad, Al-Dulaimi, Anmar January 2017 (has links)
This degree project studies the future regulations for the installation of electronic flight bags (EFB) with focus on the hardware and its safety implications in which the task was given by Bromma Air Maintenance (BAM). The aim is to ease the operator to handle issues dealing with EFB; such as lithium battery fire in the cockpit, placement of EFB in the cockpit, etc. This also addresses flight safety, flight controls, emergency evacuation and solutions in dealing with such issues. Flight safely is a vital factor to be considered since it jeopardizes lives. As recent reports indicate an increase in lithium battery powered devices incidents on aircrafts, this paves the way to find new solutions and procedures to mitigate them. By studying the current regulations, Acceptable Means of Compliance (AMC), Advisory Circular (AC) regarding the usage/installation of EFB and future regulation draft (NPA) this study analyzed the changes, which indicated that there were not many significant changes made to the future regulation (new AMC). Although many chapter of the current AMC have been removed and introduced into a new section under AMC & GM (Guidance Material). Different placement of the EFB in cockpit has also been studied in this degree project, which has shown that depending on the placement choice of the aircraft operator there are advantages and disadvantages. This follows by studying the lithium (Li-ion) batteries: technology, mitigation of fire and procedures for lithium battery fire while also studying the recent incidents regarding lithium batteries fire and explosion in commercial and cargo flights. The solutions consist of using the latest technology to propose a new approach to charge the batteries, and store the burning batteries as well. This lead to a smart inductive charger and a smart fire contamination bag to be integrated into the procedures. / Detta examensarbete studerar de framtida installationskrav för Electronic Flight Bag (EFB) med fokus på hårdvaran och dess påverkan på säkerheten. Rapporten kan användas som manual som tydliggör vilka procedurer och rekommendationer operatören kan ta hänsyn till vid installation och användning av EFB. I flygbranschen har de flesta flygbolag redan börjat använda surfplattor istället för dokument och manualer. EFB är ett elektroniskdisplaysystem som i första hand används i flygplanets cockpit. EFB:s funktion är att förse piloten med en mängd olika data om flygplanet t.ex. prestanda, balans och vikt beräkningar, bränsle mm. Displayen är en ersättning av det traditionella ”Flight Bag” som för i tiden var i pappersform och innehöll alla kartor och manualer skriftligt. Som alla andra teknologier har EFB sina begränsningar såsom batteriproblem, påverkan på säkerheten och ”Flight Controls” i flygplanets cockpit. Genom studier och sammanfattning av skillnaden mellan nuvarande och framtida regelverk har man kommit fram till att inga märkbara förändringar har skett. Fältstudien var till nytta för att analysera vilka säkerhetsproblem varje installationstyp har. Utrustningar som smart induktiv laddare och smart brandskyddsväska har fåtts som resultat i arbetet. Dessa utrustningar är till att motverka faror som är möjliga att ske under användning av EFB i cockpit.
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Simulation of hard projectile impact on friction stir welded plateWang, Wei 12 1900 (has links)
A numerical simulation is conducted using LS-DYNA to simulate hard projectile impact on a friction stir welded (FSW) plate. As the hard projectile has a wide range of velocity, mass and shape, when referring to AMC 25.963(e) of CS-25, ―Fuel Tank Access Cover‖, the hard projectile can be defined as 9.5 mm cubic-shaped steel engine debris with an initial impact velocity of 213.4 m/s (700 ft/s). This preliminary study was to evaluate whether the fuel tank adjacent skin panel joined by FSW would pass the regulation. First, the geometry and Johnson-Cook material model of the FSW joint were developed based on previous experimental research and validated by comparison with the tensile test on the FSW specimen. Then the impact on an Aluminium Alloy 2024 (AA 2024) plate without FSW was modelled. The minimum thickness of a homogeneous AA 2024 plate which could withstand the impact from engine debris is 3 mm. Finally the impact on 3 mm thick AA 2024 FSW plate was simulated. The welding induced residual stress was implemented in the plate model. The impact centre was changed from the nugget zone to the thermo-mechanically affected zone, heat-affected zone and base material zone of the FSW joint. Penetration only occurred in the model with impact centre on the nugget zone. Additional simulation indicated that increasing the thickness of the FSW plate to 3.6 mm could prevent the penetration.
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Essays on Dynamic Value Change Perspective in Resource Based View, Determinants of Alliance Formation and Risk Preference in Alliance FormationJun, Ik Su 2009 December 1900 (has links)
No description available.
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Log-Periodic Microstrip Patch Antenna Miniaturization Using Artificial Magnetic Conductor SurfacesAlmutawa, Ahmad Tariq 01 January 2011 (has links)
Microstrip patch antennas are attractive for numerous military and commercial applications due to their advantages in terms of low-profile, broadside radiation, low-cost, low-weight and conformability. However, the inherent narrowband performance of patch antennas prohibits their use in systems that demand wideband radiation. To alleviate the issue, an existing approach is to combine multiple patch antennas within a log-periodic array configuration. These log-periodic patch antennas (LPMAs) are capable of providing large bandwidths (>50%) with stable broadside radiation patterns. However, they suffer from electrically large sizes. Therefore, their miniaturization without degrading the bandwidth performance holds promise for extending their use in applications that demand conformal and wideband installations.
In recent years, electromagnetic band gap structures have been proposed to enhance the radiation performances of printed antennas. These engineered surfaces consist of a periodic arrangement of unit cells having specific metallization patterns. At particular frequencies, they provide a zero-degree phase shift for reflected plane waves and effectively act as high impedance surfaces. Since, their band-limited electromagnetic field behavior is quite similar to a hypothetical magnetic conductor; they are also referred to as artificial magnetic conductors (AMCs). AMC structures were shown to allow lower antenna profile, larger bandwidth, higher gain, and good unidirectional radiation by alleviating the field cancellation effects observed in ground plane backed antenna configurations.
Previous research studies have already demonstrated that microstrip patch antennas can enjoy significant size reductions when placed above the AMC surfaces. This project, for the first time, investigates the application of AMCs to LPMA configurations. Specifically, the goal is to reduce the LPMA size while retaining its highly desired large bandwidth performance. To accomplish this, we employ various AMC surface configurations (e.g. uniform, log-periodic) under traditional LPMAs and investigate their performance in terms of miniaturization, bandwidth, gain, and radiation patterns.
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Performance Management Systems in Albanian Mobile Operators – Two Case StudiesPone, Dorian January 2012 (has links)
This thesis explores the components of the MCSs in use by two Albanian Mobile Operators AMC and Eagle. The methodology used is that of multiple case studies; the study is interpretative, analyzing qualitative data, and has an inductive approach. There are three MCS frameworks used the Object of Control (Merchant and Van der Stede 2007), Control Package (Malmi and Brown 2008) and Performance Management Systems (Otley and Ferreira 2009). The empirical findings were gathered by using semi-structured interviews. Both managerial and non-managerial staff were interviewed according to their areas of expertise in MCSs. The findings suggest that the MCSs used by the two operators are highly structured as per the three frameworks, that AMC does not use any well known model (such as BSC, Tableau de Bord, Performance Prism etc.), whereas Eagle uses a customized BSC, and that the strategies of each of the companies are translated into action through the respective MCSs.
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Performance Management Systems in Albanian Mobile Operators - Two Case StudiesPone, Dorian January 2012 (has links)
This thesis explores the components of the MCSs in use by two Albanian Mobile Operators AMC and Eagle. The methodology used is that of multiple case studies; the study is interpretative, analyzing qualitative data, and has an inductive approach. There are three MCS frameworks used the Object of Control (Merchant and Van der Stede 2007), Control Package (Malmi and Brown 2008) and Performance Management Systems (Otley and Ferreira 2009). The empirical findings were gathered by using semi-structured interviews. Both managerial and non-managerial staff were interviewed according to their areas of expertise in MCSs. The findings suggest that the MCSs used by the two operators are highly structured as per the three frameworks, that AMC does not use any well known model (such as BSC, Tableau de Bord, Performance Prism etc.), whereas Eagle uses a customized BSC, and that the strategies of each of the companies are translated into action through the respective MCSs.
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Real-World Considerations for RFML ApplicationsMuller, Braeden Phillip Swanson 20 December 2023 (has links)
Radio Frequency Machine Learning (RFML) is the application of ML techniques to solve problems in the RF domain as an alternative to traditional digital-signal processing (DSP) techniques. Notable among these are the tasks of specific emitter identification (SEI), determining source identity of a received RF signal, and automated modulation classification (AMC), determining the modulation scheme of a received RF transmission. Both tasks have a number of algorithms that are effective on simulated data, but struggle to generalize to data collected in the real-world, partially due to the lack of available datasets upon which to train models and understand their limitations. This thesis covers the practical considerations for systems that can create high-quality datasets for RFML tasks, how variances from real-world effects in these datasets affect RFML algorithm performance, and how well models developed from these datasets are able to generalize and adapt across different receiver hardware platforms. Moreover, this thesis presents a proof-of-concept system for large-scale and efficient data generation, proven through the design and implementation of a custom platform capable of coordinating transmissions from nearly a hundred Software-Defined Radios (SDRs). This platform was used to rapidly perform experiments in both RFML performance sensitivity analysis and successful transfer between SDRs of trained models for both SEI and AMC algorithms. / Master of Science / Radio Frequency Machine Learning (RFML) is the application of machine learning techniques to solve problems having to do with radio signals as an alternative to traditional signal processing techniques. Notable among these are the tasks of specific emitter identification (SEI), determining source identity of a received signal, and automated modulation classification (AMC), determining the data encoding format of a received RF transmission. Both tasks have practical limitations related to the real-world collection of RF training data. This thesis presents a proof-of-concept for large-scale, efficient data generation and management, as proven through the design and construction of a custom platform capable of coordinating transmissions from nearly a hundred radios. This platform was used to rapidly perform experiments in both RFML performance sensitivity analysis and successful cross-radio transfer of trained behaviors.
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Caractérisation expérimentale et optimisation de procédés plasma pour la décontamination de l'AMC (Contamination Moléculaire Aéroportée) / Experimental characterization and optimization of plasma processes for the decontamination of the AMC (Airborne Molecular Contamination)Laurent, Christopher 19 December 2016 (has links)
Un problème majeur en microélectronique est la contamination moléculaire aéroportée qui dégrade les substrats et les masques diminuant le rendement de production des composants. L'utilisation de boîtes de transport en polymères pour le stockage des substrats favorise la contamination moléculaire croisée entre les deux éléments. Il est alors primordial d'avoir un procédé de décontamination des boîtes efficace et rapide. Dans le cadre de cette thèse, plusieurs solutions de décontamination par plasmas ont été étudiées. Les plasmas étaient générés selon quatre couplages énergétiques en utilisant des excitations radiofréquence (13,56 MHz) et micro-onde (2,45 GHz). Ils étaient caractérisés avec une sonde de Langmuir et un spectromètre optique sous différentes conditions expérimentales. Enfin, un protocole de contamination au fluorure d'hydrogène a été développé pour évaluer et comparer l'efficacité de décontamination des procédés plasma à ceux utilisés actuellement en microélectronique. / Un problème majeur en microélectronique est la contamination moléculaire aéroportée qui dégrade les substrats et les masques diminuant le rendement de production des composants. L'utilisation de boîtes de transport en polymères pour le stockage des substrats favorise la contamination moléculaire croisée entre les deux éléments. Il est alors primordial d'avoir un procédé de décontamination des boîtes efficace et rapide. Dans le cadre de cette thèse, plusieurs solutions de décontamination par plasmas ont été étudiées. Les plasmas étaient générés selon quatre couplages énergétiques en utilisant des excitations radiofréquence (13,56 MHz) et micro-onde (2,45 GHz). Ils étaient caractérisés avec une sonde de Langmuir et un spectromètre optique sous différentes conditions expérimentales. Enfin, un protocole de contamination au fluorure d'hydrogène a été développé pour évaluer et comparer l'efficacité de décontamination des procédés plasma à ceux utilisés actuellement en microélectronique.
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