Stokes Vector Modulation of Optical Signals; Coherence, Noise, and Digital Signal Processing

Stokes vector modulation (SVM) is a method of encoding information onto an optical wave by controlling its amplitude and its state of polarization (SOP). SVM offers the potential to achieve the high spectral efficiency of multi-dimensional symbols using a power-efficient, direct-detection receiver. Combining the two independent degrees of freedom representing polarization with one representing amplitude, SVM symbols are defined in a 3-D space of Stokes vectors, where vector length represents the amplitude and altitude/azimuth angles represent the SOP. The recoverable information content is fundamentally limited by the noise on the received signal, which may include shot noise due to photon-counting, electrical circuit noise, amplified spontaneous emission due to optical amplifiers, and self-interference of low-coherence light sources. Some of these noise terms do not obey the usual approximation of additive white Gaussian noise, and some may not be isotropic in Stokes space. Taking these complexities into account, I will theoretically analyze and compare several recently-proposed SVM receiver designs under different conditions of source coherence and channel impairments. For the most promising options, I will design symbol constellations and receiver decision strategies suitable for maximal data throughput. Construction and operation of apparatus to experimentally verify bit-error performance up to at least 10 Gsym/s with different sources, constellations, fiber spans, and receivers will be an essential component of the work. Possible extensions may include simultaneous modulation of the degree of polarization, to create a 4-D symbol space. Further, I will develop and characterize a system based on a cubic constellation for 8-SVM, using an off-the-shelf integrated modulator driven with simple bias points and data waveforms. Symbol error rates (SER) and bit error rates BER) are measured up to 30 Gb/s, and analysis of the symbol errors reveals a significant effect of inter-symbol interference. Finally, I will theoretically and experimentally demonstrate a novel adaptation of independent component analysis (ICA) for compensation of both cross-polarization and inter-symbol interference in a direct-detection link using Stokes vector modulation (SVM). SVM systems suffer from multiple simultaneous impairments that can be difficult to resolve with conventional optical channel DSP techniques. The proposed method is based on a six-dimensional adaptation of ICA that simultaneously derotates the SVM constellation, corrects distortion of constellation shape, and mitigates inter-symbol interference (ISI) at high symbol rates. Experimental results at 7.5 Gb/s and 15Gb/s show that the newly-developed ICA-based equalizer achieves power penalties below ~1 dB, compared to the ideal theoretical bit-error rate (BER) curves. At 30-Gb/s, where ISI is more severe, ICA still enables polarization de-rotation and BE

Spectral and Transport Properties of Quantum Wires with Bond Disorder

Systems with bond disorder are defined through lattice Hamiltonians that are of pure nearest neighbour hopping type, i.e. do not contain on-site contributions. Previous analyses based on the Dorokhov-Mello-Pereyra-Kumar (DMPK) transfer matrix technique have shown that both spectral and transport properties of quasi one-dimensional systems belonging to this category are highly unusual. Notably, regimes with absence of exponential Anderson localization are observed, the single particle density of states exhibits singular structure in the vicinity of the band centre, and the manifestation of these phenomena depends in an apparently topological manner on the even- or oddness of the channel number. In this paper we re-consider the problem from the complementary perspective of the non-linear sigma-model. Relying on the standard analogy between one-dimensional statistical field theories and zero-dimensional quantum mechanics, we will relate the problem to the behaviour of a quantum point particle subject to an Aharonov-Bohm flux. We will re-derive previous DMPK results, identify a new class of even/odd staggering phenomena and trace back the anomalous behaviour of the bond disordered system to a simple physical mechanism, viz. the flux periodicity of the quantum Aharonov-Bohm system. We will also touch upon connections to the low energy physics of other lattice systems, notably disordered chiral systems in 0 and 2 dimensions and antiferromagnetic spin chains.Comment: 55 pages, 2 figures include

Gaze Behaviour during Space Perception and Spatial Decision Making

A series of four experiments investigating gaze behavior and decision making in the context of wayfinding is reported. Participants were presented with screen-shots of choice points taken in large virtual environments. Each screen-shot depicted alternative path options. In Experiment 1, participants had to decide between them in order to find an object hidden in the environment. In Experiment 2, participants were first informed about which path option to take as if following a guided route. Subsequently they were presented with the same images in random order and had to indicate which path option they chose during initial exposure. In Experiment 1, we demonstrate (1) that participants have a tendency to choose the path option that featured the longer line of sight, and (2) a robust gaze bias towards the eventually chosen path option. In Experiment 2, systematic differences in gaze behavior towards the alternative path options between encoding and decoding were observed. Based on data from Experiments 1 & 2 and two control experiments ensuring that fixation patterns were specific to the spatial tasks, we develop a tentative model of gaze behavior during wayfinding decision making suggesting that particular attention was paid to image areas depicting changes in the local geometry of the environments such as corners, openings, and occlusions. Together, the results suggest that gaze during a wayfinding tasks is directed toward, and can be predicted by, a subset of environmental features and that gaze bias effects are a general phenomenon of visual decision making

Rekurrenttien neuroverkkojen käyttäminen kohteiden tunnistamiseen videoissa

This thesis explores recurrent neural network based methods for object detection in video sequences. Several models for object recognition are compared by using the KITTI object tracking dataset containing photos taken in an urban traffic environment. Metrics such as robustness to noise and object velocity prediction error are used to analyze the results. Neural networks and their training methodology is described in depth and recent models from the literature are reviewed. Several novel convolutional neural network architectures are introduced for the problem. The VGG-19 deep neural network is enhanced with convolutive recurrent layers to make it suitable for video analysis. Additionally a temporal coherency loss term is introduced to guide the learning process. Velocity estimation has not been studied in the literature and the velocity estimation performance was compared against a baseline frame-by-frame object detector neural network. The results from the experiments show that the recurrent architectures operating on video sequences consistently outperform an object detector that only perceives one frame of video at once. The recurrent models are more resilient to noise and produce more confident object detections as measured by the standard deviation of the predicted bounding boxes. The recurrent models are able to predict object velocity more accurately from video than the baseline frame-by-frame model

Monitoring War Destruction from Space Using Machine Learning

Satellite imagery is becoming ubiquitous. Research has demonstrated that artificial intelligence applied to satellite imagery holds promise for automated detection of war-related building destruction. While these results are promising, monitoring in real-world applications requires high precision, especially when destruction is sparse and detecting destroyed buildings is equivalent to looking for a needle in a haystack. We demonstrate that exploiting the persistent nature of building destruction can substantially improve the training of automated destruction monitoring. We also propose an additional machine-learning stage that leverages images of surrounding areas and multiple successive images of the same area, which further improves detection significantly. This will allow real-world applications, and we illustrate this in the context of the Syrian civil war

THE ANALYSIS OF READING EXERCISE IN “PATHWAY TO ENGLISH”, AN ENGLISH TEXTBOOK FOR SENIOR HIGH SCHOOL GRADE X, PUBLISHED BY ERLANGGA 2017

Lina Atika. 2017. The Analysis of Reading Exercise in “Pathway to English”, An English Textbook For Senior High School Grade X, Published bvy Erlangga. Thesis. English Education Study Program, Islamic Education and Teacher Trainning Faculty. Advisors : Hj. Suprapti, M. Pd Key words : Analysis, Reading Exercise, Pathway to English, Curriculum 2013 The purpose of this study is to find whether or not the mterials provided in the English textbook “Pathway to English” designed for the first grade of Senior High School compatible with the curriculum 2013. Beside that the researcher also studies about the content and relevancy with the curriculum of the textbook. This study uses descriptive qualitative reserarch. The data collected for this study will be gathered from the English textbook “Pathway to English” published by Erlangga. The data about type of text and type of exercise in reading exercise then will be analyzed. The results findings of this study concluded that (1) the English Textbook of “Pathway to English” is relevance with the curriculum 2013, as every single KI and KD succesfully implemented in the textbook. (2) the materials provided in the textbook complitely developed, as all suggested English language skill of reading exercise with the materials of the curriculum 2013 are implemented. (3) The relevancy of content in reading exercise is relevant with the curriculum 2013. Based on the findings of this study the researcher suggested that both English teachers and educational institution should concern and pay attention with the content of the textbook, not only its compatible ith the current curriculum, but also the compatible ith students‟ needs

Developing a Pedestrian Route Network Service (PRNS)

Route network service is becoming increasingly popular. However, although there are significant amount of route network services there are still limitations especially to pedestrian network services. Pedestrians daily make decision about their navigation choices. Developing a pedestrian route network service (PRNS) involves several factors. During this study the analysis of several routing network services have demonstrated that the geographical data is one of the most important factors in order to develop an own PRNS. Considering the idea of estimation two different datasets for the PRNS were evaluated OpenStreetMap (OSM) and Swedish national road database (NVDB). The use of the OSM dataset for developing the PRNS was made after the comparison between both the dataset. OSM has shown more advantages in terms of completeness of route for pedestrian navigation than NVDB. The OSM dataset was created and stored in the PostGIS database. The implementation of own pedestrian network service is intended to facilitate the developments of new PRNS and analysis and comparison of others existing PRNS. The calculation and collection of the routes to be displayed for the user are performed by extended tools within PostGIS such as pgRouting and PostgreSQL respectively. The dataset’s network topology is related to the distance and determination of route choice by the pedestrian. Thus, Geographical Information System (GIS) is also one fundamental factor used in this study to evaluate and create results. The application was implemented in the city of Lund. One of the limitations developing the PRNS is the lack of documentation for new functions which are released by pgRouting developers. Although OSM provides an essential network for developing the PRNS, some closed residential areas, parks, and open areas are not include on the network limiting the PRNS application. In conclusion the PRNS is a useful application in order to assist pedestrians on their wayfinding in the city of Lund. It is also intended to help further development of new PRNS such as mobile PRNS applications. However, the PRNS must be improved and the dataset network requires updating and expansion for successful operations of the PRNS applications.Navigeringstjänster blir allt mer populära, men även om det finns en betydande mängd tjänster, finns det fortfarande begränsningar, speciellt för fotgängare. Fotgängare gör dagligen flera val om hur de ska hitta den bästa vägen i sin närmiljö. Att utveckla en navigeringstjänst för gående (PRNS) involverar flera viktiga faktorer. I denna studie analyseras flera befintliga nättjänster och studien visar att geografiska data är en av de viktigaste faktorerna för att utveckla egna PRNS. Två olika datamängder för PRNS utvärderades: OpenStreetMap (OSM) och svenska nationella vägdatabasen (NVDB). Efter en första utvärdering av de två datamängderna valdes OSM som visade sig ha flera fördelar för en fotgängares navigering. Implementeringen av en egen navigeringstjänst för gående är avsedd att underlätta utvecklingen av nya PRNS och analysering och jämförelsen av andra befintliga PRNS. pqRouting och PostgreSQL beräknar och samlar in de rutter som ska användas, med hjälp av datamängden som finns i databasen PostGIS. Topologin för nätverket i datamängden är relaterat till avstånden och fotgängaren bestämmer vägvalet. Geografiska informationssystem (GIS) är också en grundläggande faktor som används i den här studien för att analysera resultatet. PRNS implementerades i staden Lund och syftet är att underlätta för fotgängare att navigera i staden. En av begränsningarna vid utvecklandet av PRNS är bristen på dokumentation av vissa nya funktionaliteter i pgRouting. Även om OSM tillhandahåller ett grundläggande nätverk av vägar för utvecklingen av PRNS, så saknas information om vissa bostadsområden, parker och allmänna utrymmen, vilket begränsar PRNS. Sammanfattningsvis så är PRNS ett användbart program för att hjälpa fotgängare att välja väg i staden Lund. Vidare utveckling av PRNS kan exempelvis vara en mobilapplikation. Då måste dock PRNS förbättras och datamängden kräver uppdatering och utveckling för att bli framgångsrik.Internet based applications for finding shortest ways to travel are becoming increasingly popular. However, although there are significant amount of these applications there are still limitations especially for pedestrian. Developing an internet based application service for pedestrian involves several steps. During this study the analysis of several internet based applications service for pedestrian have demonstrated that the geographical data is one of the most important components in order to develop the PRNS. Two different dataset were evaluated OpenStreetMap (OSM) and Swedish national road database (NVDB). The use of the OSM dataset for developing the PRNS was made after the comparison between both the dataset. OSM has shown more advantages in terms of completeness of roads network and ways for pedestrian than NVDB. The OSM dataset was created and stored in a database called PostGIS. The calculation of distances and collection of the shortest ways to be displayed for the user are performed by extended tools and programs within PostGIS such as pgRouting and PostgreSQL respectively. The distance and determination of the shortest ways to walk is based on the structure of the dataset and the user choice. Thus, application such as Geographical Information System (GIS) is also one fundamental component used in this study, for example, to evaluate and create maps for visual analysis. One of the limitations developing the PRNS is the lack of documentation for new functions which are released by developers. Some closed residential areas, parks, and open areas are not included on the network limiting the PRNS application. In conclusion the PRNS is a useful application in order to assist pedestrians on their wayfinding in the city of Lund. It is also intended to help further development of new PRNS such as mobile PRNS applications. However, the PRNS must be improved and the dataset network requires updating and expansion for successful operations of the PRNS applications

A Preconditioned Conjugated Gradient Method for Computing Ground States of Rotating Dipolar Bose-Einstein Condensates via Kernel Truncation Method for Dipole-Dipole Interaction Evaluation

International audienceIn this paper, we propose an efficient and accurate method to compute the ground state of 2D/3D rotating dipolar BEC by incorporating the Kernel Truncation Method (KTM) for Dipole-Dipole Interaction (DDI) evaluation into the newly-developed Preconditioned Conjugate Gradient (PCG) method [9]. Adaptation details of KTM and PCG, including multidimensional discrete convolution acceleration for KTM, choice of the preconditioners in PCG, are provided. The performance of our method is confirmed with extensive numerical tests, with emphasis on spectral accuracy of KTM and efficiency of ground state computation with PCG. Application of our method shows some interesting vortex lattice patterns in 2D and 3D respectively

A systematic study of Brain Tissue microstructure: from composition to biomechanics and modelling of White Matter

This thesis aims to shed light on the biomechanical knowledge of the brain, in particular of its white matter (WM). An extensive, multidisciplinary and bottom-up research has been carried out to understand its micromechanical response focusing on three areas: Corpus Callosum, Corona Radiata and Fornix. Axons and the surrounding matrix with its accessory cells, the two main components of the tissue, have been analysed via Focused Ion Beam Scanning Electron Microscopy (FIB-SEM). Tissue volumes have been sampled, stained, embedded and imaged to finally be 3D-reconstructed, appearing as unidirectional composite materials. They have been geometrically characterised, creating a location-specific database of: cross-sectional area, diameter, ellipticity and tortuosity of the axons, together with the volume fraction of the volumes. The AFM-enabled nanoindentations investigated the mechanical response of WM. Stress-relaxation experiments have been performed on samples with axons running either parallel or perpendicular to the testing plane. The tissue showed linear viscoelasticity and slight anisotropy at the investigated level. The perpendicular samples showed a higher initial stiffness than parallel samples while the relative change in stiffness after relaxation was higher for the parallel samples than for the perpendicular ones. Finally, micromechanical modelling of the areas was performed. Location-speci c Representative Volume Elements have been created with the geometrical info obtained via FIB-SEM. Via an inverse-modelling approach, using the AFM data, material parameters of the axons and the matrix, the tissue components, have been obtained. The predicted stress-relaxation curves simulated by the finite element analysis showed good agreement with the experimental curves. The acquired knowledge of the microenvironment is fundamental for a comprehensive microscopical characterisation of the white matter. It provides important information to reduce axonal damage during neurosurgery, by predicting the local mechanical response and planning accordingly, and to improve the efficacy and therapeutic reach of Convection Enhanced Delivery, by exploiting the cytoarchitecture, leading to minimal side effects and maximal efficacy of the treatments.Open Acces