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Key-value stores (e.g., Memcached) and web servers (e.g., NGINX) are widely used by cloud providers. As interactive services, they have strict service-level objectives, with typical 99th-percentile tail latencies on the order of a few milliseconds. Unlike average latency, tail latency is more sensitive to changes in usage load and traffic patterns, system configurations, and resource availability...
The teaching of electrical machines and drives requires a new approach to make them more attractive to students, to address and overcome the limitations of time and resources that are usual in electrical engineering programs. The target of this new approach is that after following the course students should have a consistent knowledge and skills on electric machines and drives that gives them the...
This work presents a control strategy for grid-connected voltage source inverters in Distributed Power Generation. The proposal combines two control loops, an internal loop based on the Robust Predictive Current Control (RPCC) and an external proportional-resonant with harmonic compensators (PR+HC) to achieve high rejection to external perturbations and improve grid current THD in steady state. The...
This work presents a dead-time compensation technique for robust predictive current control of grid-connected voltage source inverter. Among current controls, dead-beat predictive controllers are one of the fastest, but are extremely sensitive to inconsistencies between the model and the actual plant. Dead-time modifies the plant model and is one of the main sources of distortion in high dynamic range...
A new type of linear-programming based Model Predictive Control (LP-MPC) is presented in this work. The MPC optimization process is reformulated as a linear programming problem and solved using the Simplex method. The optimization result is the duty cycle of a fixed-frequency pulse width modulator (PWM) which switches the transistors of a three-phase grid-connected voltage source inverter. In opposition...
Performance isolation is an important goal in server-class environments. Partitioning the last-level cache of a chip multiprocessor (CMP) across co-running applications has proven useful in this regard. Two popular approaches are (a) hardware support for way partitioning, or (b) operating system support for set partitioning through page coloring. Unfortunately, neither approach by itself is scalable...
CHESS-2 (CMOS HV Evaluation for Strip Sensors) is a novel ASIC strip architecture designed to investigate the feasibility of using HV-CMOS MAPS (Monolithic Active Pixel Sensors) as alternative sensors for the ATLAS Phase-II Strip Tracker Upgrade. The ASIC is optimized for signal processing, hit pixel position encoding and readout. CHESS-2 includes three independent groups of 128 strips composed of...
This paper presents a simple and fast expression recognition algorithm aimed at running in a secondary plane to provide emotion awareness for primary applications as e.g. exergames, in real time. The algorithm is based on the extraction of 19 facial landmarks which are used to detect some of the Action Units (AUs) defined in the Facial Action Coding System (FACS) and a newly created one. In addition,...
This paper presents the design of a new exergaming environment consisting of a modular middleware tool aimed at serving for intelligent adventure games. The middleware provides a modular and user-adaptive interface for data exchange between different devices (to date it supports a motion capture camera, a mobile phone, and a VR headset) and Blender. The target group is formed by young people between...
Microcalcifications are the earliest sign of breast carcinoma. Their typical size is about 1 mm, which is why it is difficult to detect for an expert. Therefore, a tool that eases their visualization becomes relevant. Segmentation gives the candidate areas that could contain microcalcifications. A preprocessing step can improve segmentation performance but the algorithm becomes database dependent...
This work compares Triangle, Maximum Entropy and Mean Peak thresholding methods to locate the optic disc in color fundus images. Localizing the optic disc is a significant task in an automated retinal image analysis process as is used on most vessel segmentation, disease diagnostic, and retinal recognition algorithms. The DIARETDBv1 dataset includes 89 retinal images are used to evaluate the 3 thresholding...
The need for upkeep and management of medical technology has fostered the creation of a large number of under graduate programs in the field of biomedical Engineering. In Latin America alone, there are over 85 programs dedicated to this. This contrasts with programs in other regions where most of the undergraduates continue on to pursue graduate degrees or work as research and development engineers...
In recent years, photovoltaic systems designers have been started to pay attention in transformerless multilevel inverter topologies. This is due to they possess several advantages, such as, high efficiency, good performance, multiple voltage output levels and small size. In order to meet the safety requirement for transformerless grid-tied photovoltaic inverters, the leakage current has to be tackled...
This paper presents a topology and a modulation scheme for a single-phase multi-level inverter referred as asymmetrical NPC. The proposed topology is formed by two legs, namely, a NPC and a standard two-level leg, where The NPC leg allows access to the middle point of the DC source. The proposed asymmetrical NPC is able to produce an output with f ve voltage levels. The proposed modulation algorithm...
The current work proposes an algorithm for implementing a 32-bits chaotic map; which is implemented in an 8-bits microcontroller. For the algorithm, many operations are modified. The operations consist on multiplication, accommodation, addition, and shifting; the modifications are needed because the embedded operations were originally designed for 8-bit numbers. Once the microcontroller algorithm...
This paper presents a real-time simulation of a closed loop DC-DC converter implemented in a FPGA platform and programmed with LabVIEW. This implementation allows to generate a user friendly interface that facilitates the analysis and design of control techniques. As a particular case study a Buck converter is simulated with a PI digital controller to keep constant the output voltage. The real-time...
This work proposes a valve model that uses cardiac cycle phases and the flow control in order to model a closer representation of their operation based on its shape and values of the blood flow through the valve to study some dysfunctions such as aortic stenosis and how these affect cardiovascular dynamics. This dynamic model uses the 3 phases of a real valve operation; quick opening, slow closing,...
Maximum a posteriori probability (MAP) inference on Markov random fields (MRF) is the basis of many computer vision applications. Sequential tree-reweighted belief propagation (TRW-S) has been shown to provide very good inference quality and strong convergence properties. However, software TRW-S solvers are slow due to the algorithm's high computational requirements. A state-of-the-art FPGA implementation...
Multiple myeloma is a disease primarily affecting bone marrow. This paper presents a novel method that can automatically detect infiltration of the bone marrow by multiple myeloma in diseased femurs (thigh bones) from low-dose CT images. This detection is done by evaluating two aspects of the CT images: bone marrow infiltrations (increased density values compared to regular fatty bone marrow) and...
This paper describes the development of a software complement for Blender (a freely available animation software) which allows to insert motion data obtained from a motion capture camera device. The main target is to provide Blender with a tool to develop exergames, i.e. serious games for performing physical exercises, which are fully adaptive to the user's needs and capabilities, especially addressing...
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