Clustering is one of unsupervised learning algorithm to group similar objects into the same cluster and the objects in the same cluster are more similar to each other than those in the other clusters. Forecasting is making prediction based on the past data and efficient artificial intelligence models to predict data developing tendency, which can help to make appropriate decisions ahead. The datasets used in this thesis are the signal attenuation time series data from the microwave networks. Microwave networks are communication systems to transmit information between two fixed locations on the earth. They can support increasing capacity demands of mobile networks and play an important role in next generation wireless communication technology. But inherent vulnerability to random fluctuation such as rainfall will cause significant network performance degradation. In this thesis, K-means, Fuzzy c-means and 2-state Hidden Markov Model are used to develop one step and two step rain attenuation data clustering models. The forecasting models are designed based on k-nearest neighbor method and implemented with linear regression to predict the real-time rain attenuation in order to help microwave transport networks mitigate rain impact, make proper decisions ahead of time and improve the general performance. / Clustering is een van de unsupervised learning algorithmen om groep soortgelijke objecten in dezelfde cluster en de objecten in dezelfde cluster zijn meer vergelijkbaar met elkaar dan die in de andere clusters. Prognoser är att göra förutspårningar baserade på övergående data och effektiva artificiella intelligensmodeller för att förutspå datautveckling, som kan hjälpa till att fatta lämpliga beslut. Dataseten som används i denna avhandling är signaldämpningstidsseriedata från mikrovågsnätverket. Mikrovågsnät är kommunikationssystem för att överföra information mellan två fasta platser på jorden. De kan stödja ökade kapacitetsbehov i mobilnät och spela en viktig roll i nästa generationens trådlösa kommunikationsteknik. Men inneboende sårbarhet för slumpmässig fluktuering som nedbörd kommer att orsaka betydande nätverksförstöring. I den här avhandlingen används K-medel, Fuzzy c-medel och 2-state Hidden Markov Model för att utveckla ett steg och tvåstegs regen dämpning dataklyvningsmodeller. Prognosmodellerna är utformade utifrån k-närmaste granne-metoden och implementeras med linjär regression för att förutsäga realtidsdämpning för att hjälpa mikrovågstransportnät att mildra regnpåverkan, göra rätt beslut före tid och förbättra den allmänna prestandan.

Wireless transmission is an everyday part of movie production and a tool many people use in their work. Work, on a movie production, is fast, intense, and varies in geographical location almost on a daily basis (sometimes several locations in a day). Despite this, the stream, the transmission, must hold so the crew can work. This thesis explores the different impacts materials have on the transmission (using the Boxx Atom System as a test object). The materials were everyday occurrences such as walls (wood and stone), doors (steel, wood), windows (glass), and humans (the crew). The tests were done in the office of Video Assist Sweden in Stockholm, testing both quality and calculating the link margin. The results gave room for improvement but were interesting and sometimes surprising. Glass is best for a smooth transmission. Wooden doors and human beings’ impact were basically the same and stone and steel had the largest impact. In this thesis, we attempt to explain the results and draw conclusions from them and our own experiences in the field. / Trådlös överföring är en vardaglig del av en filmproduktion och ett verktyg som många använder i sitt arbete. Arbetet med en filmproduktion är snabbt, intensivt och varierar mellan olika platser nästan dagligen (ibland flera platser på en dag). Trots detta måste video transmissionen fungera så att hela teamet kan arbeta effektivt. Detta examensarbete undersöker de olika effekterna material har på transmissionen (med hjälp av Boxx Atom System som testobjekt). Materialen var vardagliga händelser som väggar (trä och sten), dörrar (stål, trä), fönster (glas) och människor (besättningen). Testerna gjordes på Video Assist Swedens kontor i Stockholm, där man testade både kvalitet och beräknade länk-marginalen. Resultaten gav utrymme för förbättringar men var intressanta och ibland överraskande. Glas är bäst för en smidig överföring. Träs och människors påverkan var i princip densamma och sten och stål hade störst påverkan. I detta examensarbete försöker vi förklara resultaten och dra slutsatser från dem och våra egna erfarenheter inom området.

[pt] Os cabos ópticos submarinos estão distribuídos por boa parte dos oceanos ao redor do globo terrestre. Esses cabos começaram a ser instalados com maior intensidade na década de 90, apesar de o primeiro cabo submarino óptico ter sido instalado em 1982 nas ilhas Canárias. Atualmente a importância dos cabos ópticos submarinos é de grande relevância para as comunicações mundiais e vem crescendo muito ao longo do tempo com a demanda por serviços de internet, liderada hoje pelas grandes empresas de tecnologia e de exploração de mídia social, tais como Google, Amazon, Meta, etc. Hoje cerca de 99 por cento de todo o tráfego da comunicação mundial da internet passa pelos cabos submarinos. Os custos para implantação desses cabos são muito altos e, portanto, prover alternativas para a ampliação da sua duração para um período maior do que a sua expectativa de vida útil representa um ganho considerável para todos. Considera-se atualmente pelos fabricantes e organismos de padronização internacional, como o ITU-T (União Internacional de Telecomunicações), uma expectativa média de vida útil de 25 anos. Esta expectativa de vida útil dada para os cabos ópticos foi a principal motivação para o desenvolvimento dessa pesquisa, cujos objetivos visam apresentar evidências que indiquem que a tendência de vida útil dos cabos ópticos submarinos pode superar os 25 anos previstos, e dessa forma contribuir para o atendimento da crescente demanda por transmissão de dados no mundo impulsionada pelos serviços de Internet. A metodologia adotada foi coletar dados de medições com o OTDR em cabos ópticos submarinos ao longo de 24 anos e avaliar a degradação sofrida pelo coeficiente de atenuação em dB/km ao longo do tempo das fibras ópticas dos cabos em operação, e comparar com a degradação sofrida pelos cabos sobressalentes, e avaliar também a degradação das perdas nas emendas submarinas e a sua correlação com a profundidade de instalação no mesmo período. As análises foram realizadas através da avaliação das curvas em arquivos na extensão .Sor obtidas com as medições realizadas pelo OTDR. Os resultados obtidos demostraram que os cabos ópticos em operação sofreram degradações compatíveis com os valores esperados e dados pelo ITU-T, mas também mostraram através da análise de curvas de tendência, que a degradação tem um comportamento logarítmico, e a projeção da curva de tendência para os próximos anos indicou que esses cabos poderão continuar em operação por muito mais anos do que os 25 anos, dados como limite anterior. Foi observado também que a penalidade de potência dada pela perda nas emendas é muito superior a degradação somente nas fibras ópticas, que existe uma correlação positiva entre a profundidade das caixas de emenda e a degradação na emenda e que os cabos sobressalentes degradam muito mais que os cabos em operação. / [en] Submarine optical cables are distributed over most of the oceans around the globe.These cables were installed with greater intensity in the 1990s, despite the fact that the firstoptical submarine cable was installed in 1982 in the Canary Islands. Currently, theimportance of submarine optical cables is very relevant for world communications and hasbeen growing a lot over time with the demand for internet services, led today by largetechnology and social media companies such as Google, Amazon, Meta, etc. Today around 99 percent of all world internet communication goes through undersea cables. The costs forimplanting these cables are very high and, therefore, to provide alternatives for optimizingtheir use by extending their duration for a period longer than their expected useful life,given by international standardization bodies, such as the ITU-T (InternationalTelecommunications Union), and by the manufacturers, which currently is 25 years, is ahuge gain for everyone. The life expectancy given for optical cables was the mainmotivation for the development of this research, whose objectives aim to present evidencethat indicates that the useful life trend of submarine optical cables can reach much morethan the 25 years predicted and in this way contribute to meeting the growing demand fordata transmission in the world, driven by Internet services. The adopted methodology wasto collect measurement data with the OTDR in submarine optical cables over 24 years andto evaluate the degradation suffered by the attenuation coefficient in dB/Km over time ofthe optical fibers of the cables in operation and to compare with the degradation sufferedby the spare cables, and also evaluate the degradation of the losses in the underwater splicesand its correlation with the depth of installation in the same period. The analyzes werecarried out by evaluating the .Sor curves obtained with the measurements performed by theOTDR. The conclusions showed that the optical cables in operation suffered degradationscompatible with the expected values and given by the ITU-T, but also showed through theanalysis of trend curves, that the degradation has a logarithmic behavior, and the projectionof the trend curve for the coming years indicated that these cables could continue to operatefor many more years than the 25 years given as the previous limit. It was also observed thatthe power penalty given by the loss in the splices is much higher than the degradation inthe optical fibers alone, that there is a positive correlation between the depth of the spliceboxes and the degradation in the splice, and that the spare cables degrade much more thanthe cables in operation.

No description available.

Necessary for effective ambulation, head stability affords optimal conditions for the perception of visual information during dynamic tasks. This maintenance of head-in-space equilibrium is achieved, in part, by the attenuation of the high frequency impact shock resulting from ground contact. While a great deal of experimentation has been done on the matter during steady state locomotion, little is known about how head stability or dynamic visual acuity is maintained during asymmetric walking. In this study, fifteen participants were instructed to walk on a split-belt treadmill for ten minutes while verbally reporting the orientation of a randomized Landolt-C optotype that was projected at heel strike. Participants were exposed to the baseline, adaptation, and washout conditions, as characterized by belt speed ratios of 1:1, 1:3, and 1:1, respectively. Step length asymmetry, shock attenuation, high (impact) and low (active) frequency head signal power, and dynamic visual acuity scores were averaged across the first and last fifty strides of each condition. Over the course of the first fifty strides, step length asymmetry was significantly greater during adaptation than during baseline (p d =2.442). Additionally, high frequency head signal power was significantly greater during adaptation than during baseline (p d =1.227), indicating a reduction in head stability. Shock attenuation was significantly lower during adaptation than during baseline (p d =-0.679), and a medium effect size suggests that dynamic visual acuity was lower during adaptation than during baseline as well (p =0.052; d =0.653). When comparing the baseline and adaptation conditions across the last fifty strides, however, many of these decrements were greatly reduced. The results of this study indicate that the locomotor asymmetry imposed by the split-belt treadmill during the early adaptation condition is responsible for moderate decrements to shock attenuation, head stability, and dynamic visual acuity. Moreover, the relative reduction in magnitude of these decrements across the last fifty strides underscores the adaptive nature of the locomotor and visuomotor systems.

Objective assessment for the effect of hearing protectors, background noise levels, and backup alarm acoustic features on listeners' abilities to localize backup alarm signals in the horizontal dimension, as well as on their ability to detect backup alarm signals in the distance dimension, is lacking in the acoustics and safety literature. Accordingly, two research experiments were conducted for this dissertation. In the first experiment, the effect of seven hearing protectors, two background pink noise levels (60 dBA and 90 dBA), and two backup alarm signals (standard and spectrally-modified) on the ability of normal hearing listeners to localize backup alarm signals in the horizontal dimension was investigated. Results indicated that a diotic sound transmission earmuff significantly degraded localization accuracy as compared to all other hearing protectors and the open ear condition. In addition, no significant difference existed between the open ear condition and the other hearing protectors in localization accuracy in most of the conditions tested. However, the E-A-R/3M HiFiTM earplug was advantageous in localization performance since it provided a significantly higher percentage correct localization than the Moldex foam earplug, the diotic earmuff, and the dichotic earmuff in 90 dBA pink noise. As for main effects of the other independent variables, the 90 dBA pink noise significantly degraded localization performance as compared to the quiet condition of 60 dBA, and a spectrally-modified backup alarm significantly improved localization performance as compared to the standard (narrowband) backup alarm. Potential application of these results includes the revision of backup alarm standards. In addition, these results provide clear advice for safety professionals to avoid the application of diotic sound transmission earmuffs for workers if localizing backup alarms is important. In the first experiment, listeners' feeling of comfort for each hearing protector was assessed subjectively by using a comfort rating scale. In addition, a subjective assessment for listeners' confidence in their localization decisions was established. Results indicated no significant difference between the hearing protectors in terms of comfort. However, in terms of listeners' confidence in localization decisions, their confidence was significantly degraded when they were fitted with the diotic earmuff. By contrast, they showed significantly more confidence in their localization decisions when they were fitted with the E-A-R/3M HiFi™ earplug as compared to when they were fitted with the Moldex foam earplug, the E-A-R/3M Ultrafit™ earplug, and the Bilsom passive earmuff. In the second experiment, listeners' performance in detecting a stationary backup alarm signal, including both a standard (narrowband) and broadband (pulsed white noise) alarm, was determined while they were equipped with various passive and electronic hearing protection devices. Listeners' performance was quantified by detection distance, which was defined as the distance between the stationary backup alarm device and the position where the listener detected the backup alarm signal. The resultant data demonstrated that normal hearing listeners detected a standard (narrowband) backup alarm signal at significantly longer distances as compared to the broadband (Brigade™) backup alarm signal, thus indicating the earlier forewarning by the standard alarm. In addition, passive hearing protection devices characterized with high attenuation significantly reduced the detection distance. These results may be applied to assist safety professionals in selecting hearing protectors and backup alarm signals that provide on-foot workers with ample time to react to an approaching backing vehicle, thus improving their safety. / Ph. D.

Remediation of contaminated groundwater remains a high-priority national goal in the United States. Water is essential to life, and new sources of water are needed for an expanding population. Groundwater remediation remains a significant technical challenge despite decades of research into this field. New approaches are needed to address the most severely-polluted aquifers, and cost-effective solutions are required to meet remediation objectives that protect human health and the environment. Source reduction combined with Monitored Natural Attenuation (MNA) is a remediation strategy whereby the source of contamination is aggressively treated or removed and the residual groundwater plume depletes due to natural processes in the subsurface. The USEPA requires long-term performance monitoring of groundwater at MNA sites over the remediation timeframe, which often takes decades to complete. Presently, computational tools are lacking to adequately integrate source remediation with economic models. Furthermore, no framework has been developed to highlight the tradeoff between the degree of remediation versus the level of benefit within a cost structure. Using the Natural Attenuation Software (NAS) package developed at Virginia Tech, a set of formulae have been developed for calculating the TOR for petroleum-contaminated aquifers (specifically tracking benzene and MTBE) through statistical techniques. With the knowledge of source area residual saturation, groundwater velocity, and contaminant plume source length, the time to remediate a site contaminated with either benzene or MTBE can be determined across a range of regulatory maximum contaminant levels. After developing formulae for TOR, an integrated and interactive decision tool for framing the decision analysis component of the remediation problem was developed. While MNA can be a stand-alone groundwater remediation technology, significant benefits may be realized by layering a more traditional source zone remedial technique with MNA. Excavation and soil vapor extraction when applied to the front end of a remedial action plan can decrease the amount of time to remediation and while generally more expensive than an MNA-only approach, may accrue long-term economic advantages that would otherwise be foregone. The value of these research components can be realized within the engineering and science communities, as well as through government, business and industry, and communities where groundwater contamination and remediation are of issue. Together, these tools constitute the Sâ ªEâ ªEâ ªPâ ªAGE paradigm, founded upon the concept of sound science for an environmental engineering, effectual economics, and public policy agenda. The TOR formulation simplifies the inputs necessary to determine the number of years that an MNA strategy will require before project closure and thus reduces the specialized skills and training required to perform a numerical analysis that for one set of conditions could require many hours of simulation time. The economic decision tool, that utilizes a life cycle model to evaluate a set of feasible alternatives, highlights the tradeoffs between time and economics can be realized over the lifetime of the remedial project. / Ph. D.

The advent of Internet based digital services, and bandwidth-intensive business and personal applications has necessitated deployment of broadband network access technologies. Research analysts project that the U.S. market for broadband wireless networking will grow to nearly $2 billion by 2004 and Local Multipoint Distribution Services (LMDS) have enormous potential to emerge as the most reliable and cost-effective solution. However, in order to design and deploy LMDS systems, it is vital for system designers to be able to predict the behavior of mm-waves (28, 38 and 60GHz) during different weather conditions, especially rain. This research attempts to characterize the performance of pico-cell scenario broadband wireless channels by measuring path loss statistics during different weather conditions. Hardware and software components of a wideband direct-sequence spread spectrum (DSS) channel sounding system, used extensively throughout measurement campaigns, are discussed in detail in this dissertation. The measurement plan comprehensively describes the methodology, logistics, equipment setup, and calibration procedures for propagation measurement campaigns. Power Delay Profile (PDP) snapshots recorded during measurement campaigns are thoroughly analyzed using the 'Channel Imaging Analysis Suite' and Path Loss as well as Rain Attenuation statistics, calculated from recorded PDP data files, are classified and tabulated on the basis of measurement locations, propagation frequencies and antenna polarizations. Path Loss Exponent values are also calculated and Rain Attenuation statistics are compared with popular rain models. Results from Frequency Diversity measurement campaigns are also presented. / Master of Science

Die Verschmutzung von Süßgewässern mit organischen Mikroschadstoffen ist ein Problem, das sich weltweit zunehmend verschärft. Die vorliegende Doktorarbeit soll zu einem besseren Verständnis des Verhaltens einzelner Mikroschadstoffe und deren Transformationsprodukten in Flüssen beitragen, sowie die Rolle relevanter Einflussfaktoren untersuchen. Verhalten verschiedener Stoffe wurde im Oberflächenwasser eines urbanen Flusses analysiert. Es zeigte sich, dass die Sonneneinstrahlung für einige Verbindungen der wichtigste Einflussfaktor ist, während andere eher biologisch abgebaut wurden. Die Mahd von Makrophyten hatte ebenfalls stoffspezifische Folgen auf den Abbau. Um langfristige Variabilität von Stofftransport besser zu verstehen wurde eine neue Methode zur Schätzung des Stofftransports anhand von Schwankungen der elektrischen Leitfähigkeit getestet. Einige Stofftransportparameter änderten sich über die Jahreszeiten hinweg und transiente Speicherung unterschied sich zwischen den Flussabschnitten. Um im Besonderen den Einfluss von mikrobieller Diversität und von hyporheischem Austausch zu bewerten, wurde ein Meskosmenexperiment mit 20 rezirkulierenden Fließrinnen entwickelt. Es konnte festgestellt werden, dass vor allem mikrobielle Diversität einen starken Einfluss hat. Der neue Versuchsaufbau kann zukünftig für die Untersuchung weiterer Variablen Verwendung finden. Schließlich wurden Mikroschadstoffe und Transformationsprodukte in der hyporheischen Zone der Fließrinnen analysiert. Das Verhalten war sowohl stoffspezifisch als auch fließwegspezifisch. Die Ergebnisse unterstreichen die Bedeutung des oberflächennahen, hyporheischen Austauschs auf den Stoffabbau. Im Allgemeinen konnte die hohe Variabilität des Abbaus von Mikroschadstoffen mit besonderer Relevanz der hyporheischen Zone und der mikrobiellen Diversität nachgewiesen werden. Diese Faktoren sollten in zukünftigen Forschungsvorhaben besonders berücksichtigt werden. / Contamination of freshwaters with organic micropollutants is a worldwide emerging problem. The present thesis aims to contribute to a better understanding of the variability of the behaviour of individual micropollutants, the formation of transformation products in rivers and the specific role of relevant influencing factors. The behaviour of several substances was investigated in the surface water of an urban river by accounting for spatial and temporal dynamics. Solar radiation was identified to be the major driver for some compounds, while others were more susceptible to biodegradation. The response to macrophyte removal was also compound-specific. To better understand long-term variability of solute transport on a reach-scale a new method to estimate solute transport by use of electrical conductivity fluctuations was proposed and tested. Some solute transport metrics changed over the seasons and transient storage differed between river sections. To specifically assess the influence of microbial diversity and hyporheic exchange, a mesocosm experiment with 20 recirculating flumes was developed. It was found that microbial diversity in particular had a strong impact and the novel setup was suggested to be a useful method to test other variables in the future. Finally, the behaviour of micropollutants and transformation products in the hyporheic zone of the flumes was investigated on a centimeter-scale. The behaviour was found to be compound-specific as well as flowpath-specific. But several compounds were degraded most on the shortest, most oxic flowpath. The findings highlight the importance of shallow, small-scale hyporheic exchange for turnover of micropollutants. Generally, the high variability of micropollutant degradation depending on relevant influencing factors, specifically hyporheic exchange and microbial diversity, has been demonstrated. These factors are of great importance and need to be addressed and considered in future research.

Bei der Behandlung von Tumoren und Metastasen werden neben der moderaten Hyperthermie auch minimalinvasive, thermotherapeutische Verfahren als Alternativen zur chirurgischen Resektion und / oder zur Unterstützung der Radio- und Chemotherapie angewandt, bei denen das Gewebe lokal begrenzt zur gezielten Zerstörung durch Koagulation auf Temperaturen bis zu 100 °C erhitzt wird. Dabei zeigen besonders die interstitiellen Techniken bei der Behandlung von Lebermetastasen und Prostataerkrankungen vielversprechende Ergebnisse, jedoch steht derzeit neben der Magnetresonanztomographie kein kostengünstiges, routinemäßig einsetzbares Verfahren zur nicht-invasiven on-line Therapiekontrolle zur Verfügung, so daß diese Eingriffe meist "blind", auf anatomische Normwerte und praktische Erfahrungen des Arztes gestützt, durchgeführt werden. In dieser Arbeit werden die Möglichkeiten der nicht-invasiven Ultraschall Kontrolle der Thermotherapien am Beispiel der laserinduzierten interstitiellen Thermotherapie untersucht und zwei Ultraschallverfahren zur Therapiekontrolle vorgeschlagen. Das erste Verfahren basiert auf der Auswertung von lokalen Veränderungen der Laufzeit des Schallsignals zur Ermittelung der Temperaturverteilung im Gewebe. Es beruht physikalisch auf der Temperaturabhängigkeit der Schallgeschwindigkeit. Das zweite Verfahren basiert physikalisch auf den Dämpfungseigenschaften von biologischem Gewebe und deren Abhängigkeit von der Gewebestruktur. Mit diesem Verfahren werden Veränderungen in der Frequenzabhängikeit der Dämpfung quantitativ ausgewertet und somit auf den Gewebezustand geschlossen. Beide Verfahren werden im Hinblick auf den klinischen Einsatz entwickelt und in ein experimentelles System zur Therapiekontrolle implementiert, wobei besonderes Augenmerk auf die Entstehung von Störungen und Artefakten durch Patientenbewegungen gelegt und eine Methode zur Kompensation dieser Bewegungen vorgestellt wird. Anhand von in vitro Experimenten und einer ersten in vivo Messung wird gezeigt, daß beide Verfahren zur Therapiekontrolle von thermischen Therapien in Echtzeit tauglich sind. Sowohl anhand von Temperaturkarten als auch anhand von Strukturkarten kann die Läsionsausbreitung während der Therapie nicht-invasiv ermittelt und dargestellt werden. / As alternatives to surgical resection and/or supportive to radio- or chemo-therapy of tumors and metastases minimal invasive thermal treatment procedures besides the moderate hyperthermia are used, by which the tissue is heated up locally to temperatures up to 100 ° C. Particularly the interstitial techniques show promising results with the treatment of liver metastases and prostate cancer. However beside nuclear magnetic resonance tomography there is no economical, by routine applicable procedure for non invasive therapy control at present disposal, so that these interventions are usually executed "blind" by means of anatomical standard values and practical experience of the physician. By the example of the laser induced interstitial thermo-therapy in this work the possibility of non invasive control of thermal therapies by means of ultrasound are evaluated. Two different ultrasonic procedures are proposed for therapy control. The first procedure is based on the analysis of local modifications in the time of flight of the ultrasound signal for determination of the temperature distribution in the tissue. It is based on the physical dependence of the sound velocity on temperature. The second procedure is based on the physical attenuation characteristics of biological tissue and their dependence on the tissue structure. With this procedure changes in the frequency dependence of the ultrasound attenuation are quantitatively analyzed yielding information on the tissue status. Both procedures are developed with regard to the clinical application and are implemented in an experimental system for therapy control, whereby special attention was given to disturbances and artifacts due to patient movement and a method for compensating these movements is presented. With in vitro experiments and a first in vivo measurement it is shown, that both procedures are feasible for real time control of thermal therapies. During the treatment the formation of the therapeutic lesion can be observed and displayed through temperature mapping as well as structural mapping.