# Universitat Politècnica de Catalunya

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238598 research outputs found

### Periodic economic model predictive control with nonlinear-constraint relaxation for water distribution networks

© 20xx IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.In this paper, a periodic economic model predictive control (EMPC) strategy with nonlinear algebraic constraint relaxations for water distribution networks (WDNs) is presented. A WDN is usually modeled by a series of differential-algebraic equations. When the hydraulic pressure/head and flow relations in the interconnected pipes are considered, the nonlinear algebraic equations will appear in the control-oriented model of WDNs. Specifically, two types of nonlinear algebraic equations are studied in terms of unidirectional and bidirectional flows in pipes. These nonlinear algebraic constraints are iteratively relaxed by a series of linear constraints. Therefore, the proposed EMPC strategy can be implemented by solving an optimization problem using the linear programming technique. Finally, the EMPC strategy with nonlinear algebraic constraint relaxations is verified in the Richmond water network. The comparison results of applying nonlinear EMPC strategy are also provided. The proposed nonlinear-constraint relaxation technique turns out to be much faster than the one obtained by a standard nonlinear optimization solver.Peer ReviewedPostprint (author's final draft

### Partial orderings for hesitant fuzzy sets

New partial orderings =o=o, =p=p and =H=H are defined, studied and compared on the set HH of finite subsets of the unit interval with special emphasis on the last one. Since comparing two sets of the same cardinality is a simple issue, the idea for comparing two sets A and B of different cardinalities n and m respectively using =H=H is repeating their elements in order to obtain two series with the same length. If lcm(n,m)lcm(n,m) is the least common multiple of n and m we can repeat every element of A lcm(n,m)/mlcm(n,m)/m times and every element of B lcm(n,m)/nlcm(n,m)/n times to obtain such series and compare them (Definition 2.2). (H,=H)(H,=H) is a bounded partially ordered set but not a lattice. Nevertheless, it will be shown that some interesting subsets of (H,=H)(H,=H) have a lattice structure. Moreover in the set BB of finite bags or multisets (i.e. allowing repetition of objects) of the unit interval a preorder =B=B can be defined in a similar way as =H=H in HH and considering the quotient set View the MathML sourceB¿=B/~ of BB by the equivalence relation ~ defined by A~BA~B when A=BBA=BB and B=BAB=BA, View the MathML source(B¿,=B) is a lattice and (H,=H)(H,=H) can be naturally embedded into it.Peer ReviewedPostprint (author's final draft

### The synergy of multithreading and access/execute decoupling

This work presents and evaluates a novel processor microarchitecture which combines two paradigms: access/execute decoupling and simultaneous multithreading. We investigate how both techniques complement each other: while decoupling features an excellent memory latency hiding efficiency, multithreading supplies the in-order issue stage with enough ILP to hide the functional unit latencies. Its partitioned layout, together with its in-order issue policy makes it potentially less complex, in terms of critical path delays, than a centralized out-of-order design, to support future growths in issue-width and clock speed. The simulations show that by adding decoupling to a multithreaded architecture, its miss latency tolerance is sharply increased and in addition, it needs fewer threads to achieve maximum throughput, especially for a large miss latency. Fewer threads result in a hardware complexity reduction and lower demands on the memory system, which becomes a critical resource for large miss latencies, since bandwidth may become a bottleneck.Peer ReviewedPostprint (published version

### The Xor embedding: An embedding of hypercubes onto rings and toruses

Many parallel algorithms use hypercubes as the communication topology among processes, which make them suitable to be executed on a hypercube multicomputer. In this way the communication cost is kept to a minimum since processes can be allocated to processors in such a way that only communication between neighbor processors is required. However, the scalability of hypercube multicomputer is constrained by the fact that the interconnection cost per node increases with the total number of nodes. From the point of view of scalability, meshes and toruses are a more interesting class of interconnection topologies. In this paper the authors propose an embedding of hypercubes onto toruses of any given dimension, incuding one-dimensional toruses which are also called rings. They also prove that the embedding is optimal in the sense that it minimizes the execution time on a ring of a class of parallel algorithms frequently found in real applications, such as FFT and some class of sorting algorithms.Peer ReviewedPostprint (published version

### Joint synchronization and symbol detection in asynchronous DS-CDMA systems

The design of accurate estimators which also consider the noise term in low SNR scenarios is paramount for achieving optimal solutions and obtaining precise symbol detectors. Particularly, this paper estimates the propagation delays focusing on asynchronous DS-CDMA systems. The proposed minimum conditioned variance (MCV) is the choice in noisy environments, implementing the best linear detector of the transmitted symbols under a minimum mean-square error criterion. The result is an estimator that improves the conditional ML (CML) solution when noise is not negligible, and attains the derived Gaussian unconditional Cramer-Rao bound (UCRB) in the whole EbNo range as classical Gaussian unconditional ML (UML) does. Consequently, the proposed MCV estimator, becomes an optimal quadratic solution achieving similar features than UML in a straightforward way, and with no assumptions on the signal statistics.Peer ReviewedPostprint (published version

### Cell adhesive peptides functionalized on CoCr alloy stimulate endothelialization and prevent thrombogenesis and restenosis

Immobilization of bioactive peptide sequences on CoCr surfaces is an effective route to improve endothelialization, which is of great interest for cardiovascular stents. In this work, we explored the effect of physical and covalent immoblization of RGDS, YIGSR and their equimolar combination peptides on endothelial cells (EC) and smooth muscle cell (SMC) adhesion and on thrombogenicity. We extensively investigated using RT-qPCR, the expression by ECs cultured on functionalised CoCr surfaces of different genes. Genes relevant for adhesion (ICAM-1 and VCAM-1), vascularization (VEGFA, VEGFR-1 and VEGFR-2) and anti-thrombogenicity (tPA and eNOS) were over-expressed in the ECs grown to covalently functionalized CoCr surfaces compared to physisorbed and control surfaces. Pro-thrombogenic genes expression (PAI-1 and vWF) decreased over time. Cell co-cultures of ECs/SMCs found that functionalization increased the amount of adhered ECs onto modified surfaces compared to plain CoCr, independently of the used peptide and the strategy of immobilization. SMCs adhered less compared to ECs in all surfaces. All studied peptides showed a lower platelet cell adhesion compared to TCPS. Covalent functionalization of CoCr surfaces with an equimolar combination of RGDS and YIGSR represented prevailing strategy to enhance the early stages of ECs adhesion and proliferation, while preventing SMCs and platelet adhesion.Postprint (author's final draft

### Detection and analysis of part load and full load instabilities in a real Francis turbine prototype

Francis turbines operate in many cases out of its best effici ency point, in order to regulate their output power according to the instantaneous ener gy demand of the grid. Therefore, it is of paramount importance to analyse and determine the unst able operating points for these kind of units. In the framework of the HYPERBOLE project (FP7-E NERGY-2013-1; Project number 608532) a large Francis unit was investigated numericall y, experimentally in a reduced scale model and also experimen tally and numerically in the real prototype. This paper shows the unstable operating points identified during the experimental te sts on the real Francis unit and the analysis of the main characteristics of these instabilities. Fi nally, it is shown that similar phenomena have been identified on previous research in the LMH (Laboratory for Hydraulic Machines, Lausanne) with t he reduced scale model.Postprint (published version

### Thermoconductive thermosetting composites based on boron nitride fillers and thiol-epoxy matrices

In this work, the effect of the addition of boron nitride (BN) fillers in a thiol-cycloaliphatic epoxy formulation has been investigated. Calorimetric studies put into evidence that the kinetics of the curing has been scarcely affected and that the addition of particles does not affect the final structure of the network. Rheologic studies have shown the increase in the viscoelastic properties on adding the filler and allow the percolation threshold to be calculated, which was found to be 35.5%. The use of BN agglomerates of bigger size increases notably the viscosity of the formulation. Glass transition temperatures are not affected by the filler added, but Young’s modulus and hardness have been notably enhanced. Thermal conductivity of the composites prepared shows a linear increase with the proportion of BN particle sheets added, reaching a maximum of 0.97 W/K·m. The addition of 80 µm agglomerates, allowed to increase this value until 1.75 W/K·m.Postprint (published version

### An open benchmark implementation for multi-CPU multi-GPU pedestrian detection in automotive systems

Modern and future automotive systems incorporate several Advanced Driving Assistance Systems (ADAS). Those systems require significant performance that cannot be provided with traditional automotive processors and programming models. Multicore CPUs and Nvidia GPUs using CUDA are currently considered by both automotive industry and research community to provide the necessary computational power. However, despite several recent published works in this domain, there is an absolute lack of open implementations of GPU-based ADAS software, that can be used for benchmarking candidate platforms. In this work, we present a multi-CPU and GPU implementation of an open implementation of a pedestrian detection benchmark based on the Viola-Jones image recognition algorithm. We present our optimization strategies and evaluate our implementation on a multiprocessor system featuring multiple GPUs, showing an overall 88.5× speedup over the sequential version.This work has been supported by the Spanish Ministry of Science and Innovation under grant TIN2015-65316P, the HiPEAC Network of Excellence and a Microsoft sponsored ACM SRC. The first two authors acknowledge Dr. Petrisor for her assistance in understanding and using the sequential version of the benchmark and dedicate this article to the memory of the late beloved advisor prof. Nacho Navarro, without whom this work would not have been possible.Peer ReviewedPostprint (author's final draft

### Comparative aspects in control strategies for hybrid DC/DC converters

Peer ReviewedPostprint (published version

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