2,138 research outputs found
Capacity-achieving CPM schemes
The pragmatic approach to coded continuous-phase modulation (CPM) is proposed
as a capacity-achieving low-complexity alternative to the serially-concatenated
CPM (SC-CPM) coding scheme. In this paper, we first perform a selection of the
best spectrally-efficient CPM modulations to be embedded into SC-CPM schemes.
Then, we consider the pragmatic capacity (a.k.a. BICM capacity) of CPM
modulations and optimize it through a careful design of the mapping between
input bits and CPM waveforms. The so obtained schemes are cascaded with an
outer serially-concatenated convolutional code to form a pragmatic
coded-modulation system. The resulting schemes exhibit performance very close
to the CPM capacity without requiring iterations between the outer decoder and
the CPM demodulator. As a result, the receiver exhibits reduced complexity and
increased flexibility due to the separation of the demodulation and decoding
functions.Comment: Submitted to IEEE Transactions on Information Theor
Capacity -based parameter optimization of bandwidth constrained CPM
Continuous phase modulation (CPM) is an attractive modulation choice for bandwidth limited systems due to its small side lobes, fast spectral decay and the ability to be noncoherently detected. Furthermore, the constant envelope property of CPM permits highly power efficient amplification. The design of bit-interleaved coded continuous phase modulation is characterized by the code rate, modulation order, modulation index, and pulse shape. This dissertation outlines a methodology for determining the optimal values of these parameters under bandwidth and receiver complexity constraints. The cost function used to drive the optimization is the information-theoretic minimum ratio of energy-per-bit to noise-spectral density found by evaluating the constrained channel capacity. The capacity can be reliably estimated using Monte Carlo integration. A search for optimal parameters is conducted over a range of coded CPM parameters, bandwidth efficiencies, and channels. Results are presented for a system employing a trellis-based coherent detector. To constrain complexity and allow any modulation index to be considered, a soft output differential phase detector has also been developed.;Building upon the capacity results, extrinsic information transfer (EXIT) charts are used to analyze a system that iterates between demodulation and decoding. Convergence thresholds are determined for the iterative system for different outer convolutional codes, alphabet sizes, modulation indices and constellation mappings. These are used to identify the code and modulation parameters with the best energy efficiency at different spectral efficiencies for the AWGN channel. Finally, bit error rate curves are presented to corroborate the capacity and EXIT chart designs
Precoding for Non-coherent Detection of Continuous Phase Modulations
Non-coherent trellis based receiver (TBR) is an effective method to demodulate noncoherent continuous-phase modulated sequences. However it requires to increase the observation length to reach the performance of classical coherent TBRs. Furthermore it appears that both receivers offers different behaviours when considered in a bit-interleaved coded modulation (BICM) system using iterative decoding. Indeed, trellis based outer coding schemes performing well in coherent regime generate error floors in non-coherent regime. In this paper, we show that precoding of the continuous phase modulation (CPM) encoder can deal with the latter issue. The optimization of this non-coherent precoding relies on different objectives than the existing precoding methods introduced in the coherent case. The optimization relies on some asymptotic arguments enabling an efficient BICM scheme using iterative decoding. Using the proposed precoding approach enables to remove error floors in the non-coherent regime while enabling transparent use in the coherent case
OptimitzaciĂł de la metodologia de gestiĂł de projectes PERT/CPM implementant les filosofies Lean i Agile
Treballs Finals de MĂ ster d'Enginyeria QuĂmica, Facultat de QuĂmica, Universitat de Barcelona. Curs: 2020-2021. Tutora: Maria Alicia Cardete GarciaCompanies need to tackle investment projects in order to be more competitive. The proper
management of such projects is a key factor for the company’s results. In particular, the construction
phase is a critical point since it is the stage where time and/or resources constraints do not often meet,
mainly because of the susceptibility to the acceptance of potential changes. In order to comply with
such restrictions, project managers are supported by different management techniques, such as the
widely implemented PERT/CPM (Program Evaluation and Review Technique/ Critical Path Method)
Also, some other novel methodologies are being developed, such as Lean or Agile, in the field of
project management.
The objective of this study is to assess the impact of an improved, novel combination of such project
management methodologies, on the achievement of time and resource constraints. As a methodology,
a real case-study has been addressed by showing a comparison of the results obtained with the use of
the conventional PERT/CPM methodology to the implemented of the new project management
methodology proposed. The case-study focuses on the construction phase of a revamp project in an
Ethylene Glycol plant, which consists on changing the existing structured packing from a MEG
(monoethylene glycol) distillation column to a high performance one, in order to increase capacity,
while keeping the same efficiency.
The main constraints that apply this project refer to limited affordable plant shutdown time due to
commercial reasons and also to the strictly planned availability of a specialist technician, responsible
of the most critical task, to fit in the new structured packing.
This study begins with the implementation of the PERT/CPM methodology to programme the
construction phase. Although this technique allows to identify the critical path and therefore determine
the total duration of the project, it has substantial limitations. The main one, is the lack of tools to
optimize the planning either to meet the project constraints or even to make it more reliable. The study
reveals that just applying the conventional PERT/CPM methodology based on timings experienced in
previous similar projects does not allow to accomplish with the required constraints.
For that reason, a novel methodology is developed to ensure the accomplishment of time and resources
constraints. A SWOT analysis is run to identify weaknesses and potential threats which are overcome
through the introduction of Lean and Agile techniques. As a result, a modified PERT/CPM with Agile
and Lean methodologies have been developed. Whereas PERT/CPM sets the operative basis for the
project management, its upgrade with the philosophies Agile and Lean provides a combined
framework, which not only addresses the timely organization of the activities, but also provides tools
to deal with time and resources constraints. The report reveals that this innovative combined technique ensures compliance with the established deadlines while increasing the reliability of the project's
results.
Finally, the present study proposes the implementation of a risk assessment as an objective and
rigorous methodology for the proper resource assignment, an issue which in today’s project tends to
be done either arbitrarily or on the background of previous project experiences, resulting in inefficient
resource management and high financial losses
In conclusion, because of the flexible framework provided by this innovative methodology, it can also
be applied in small improvement projects, in other sectors different from the chemical industry and
even in maintenance activities that have to be organised on a daily basis in production plants
CHANGE-READY MPC SYSTEMS AND PROGRESSIVE MODELING: VISION, PRINCIPLES, AND APPLICATIONS
The last couple of decades have witnessed a level of fast-paced development of new ideas, products, manufacturing technologies, manufacturing practices, customer expectations, knowledge transition, and civilization movements, as it has never before. In today\u27s manufacturing world, change became an intrinsic characteristic that is addressed everywhere. How to deal with change, how to manage it, how to bind to it, how to steer it, and how to create a value out of it, were the key drivers that brought this research to existence. Change-Ready Manufacturing Planning and Control (CMPC) systems are presented as the first answer. CMPC characteristics, change drivers, and some principles of Component-Based Software Engineering (CBSE) are interwoven to present a blueprint of a new framework and mind-set in the manufacturing planning and control field, CMPC systems. In order to step further and make the internals of CMPC systems/components change-ready, an enabling modeling approach was needed. Progressive Modeling (PM), a forward-looking multi-disciplinary modeling approach, is developed in order to modernize the modeling process of today\u27s complex industrial problems and create pragmatic solutions for them. It is designed to be pragmatic, highly sophisticated, and revolves around many seminal principles that either innovated or imported from many disciplines: Systems Analysis and Design, Software Engineering, Advanced Optimization Algorisms, Business Concepts, Manufacturing Strategies, Operations Management, and others. Problems are systemized, analyzed, componentized; their logic and their solution approaches are redefined to make them progressive (ready to change, adapt, and develop further). Many innovations have been developed in order to enrich the modeling process and make it a well-assorted toolkit able to address today\u27s tougher, larger, and more complex industrial problems. PM brings so many novel gadgets in its toolbox: function templates, advanced notation, cascaded mathematical models, mathematical statements, society of decision structures, couplers--just to name a few. In this research, PM has been applied to three different applications: a couple of variants of Aggregate Production Planning (APP) Problem and the novel Reconfiguration and Operations Planning (ROP) problem. The latest is pioneering in both the Reconfigurable Manufacturing and the Operations Management fields. All the developed models, algorithms, and results reveal that the new analytical and computational power gained by PM development and demonstrate its ability to create a new generation of unmatched large scale and scope system problems and their integrated solutions. PM has the potential to be instrumental toolkit in the development of Reconfigurable Manufacturing Systems. In terms of other potential applications domain, PM is about to spark a new paradigm in addressing large-scale system problems of many engineering and scientific fields in a highly pragmatic way without losing the scientific rigor
Using stratified medicine to understand, diagnose, and treat neuropathic pain
Neuropathic pain (NeuP) is defined as pain arising from a lesion or disease of the somatosensory nervous system. NeuP is common, affecting approximately 6-8% of the general population and currently treatment is inadequate due to both poor drug efficacy and tolerability. Many different types of injury can cause neuropathic pain including genetic (e.g. SCN9A gain of function variants), metabolic (e.g. diabetic polyneuropathy), infective (e.g. HIV associated neuropathy, hepatitis), traumatic and toxic (e.g. chemotherapy induced neuropathy) causes. Such injurious events can impact on anatomically distinct regions of the somatosensory nervous system ranging from the terminals of nociceptive afferents (in small fiber neuropathy) to the thalamus (in post-stroke pain). Classification of neuropathic pain using etiology and location remains an important aspect of routine clinical practice; however, pain medicine is coming to the realization that we need more precision in this classification. The hope is that improved classification will lead to better understanding of risk, prognosis and optimal treatment of NeuP
Nouvelle forme d'onde et récepteur avancé pour la télémesure des futurs lanceurs
Les modulations à phase continue (CPMs) sont des méthodes de modulations robuste à la noncohérence du canal de propagation. Dans un contexte spatial, les CPM sont utilisées dans la chaîne de transmission de télémesure de la fusée. Depuis les années 70, la modulation la plus usitée dans les systèmes de télémesures est la modulation CPFSK continuous phase frequency shift keying filtrée. Historiquement, ce type de modulation est concaténée avec un code ReedSolomon (RS) afin d'améliorer le processus de décodage. Côté récepteur, les séquences CPM non-cohérentes sont démodulées par un détecteur Viterbi à sortie dure et un décodeur RS. Néanmoins, le gain du code RS n'est pas aussi satisfaisant que des techniques de codage moderne capables d'atteindre la limite de Shannon. Actualiser la chaîne de communication avec des codes atteignant la limite de Shannon tels que les codes en graphe creux, implique deremanier l’architecture du récepteur usuel pour un détecteur à sortie souple. Ainsi, on propose dans cette étude d' élaborer un détecteur treillis à sortie souple pour démoduler les séquences CPM non-cohérentes. Dans un deuxième temps, on concevra des schémas de pré-codages améliorant le comportement asymptotique du récepteur non-cohérent et dans une dernière étape on élabora des codes de parité à faible densité (LDPC) approchant la limite de Shannon
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