Ecodesign of Low-Voltage Systems and Exposure to ELF Magnetic Fields

The Ecodesign of modern residential and commercial low-voltage systems implements energy and equipment cost savings, optimizing the size of the distribution system without compromising their functionality or causing environmental contamination, including electromagnetic pollution. Protection of persons against shock hazards should result increased, and the electrical interferences among power systems reduced. To achieve the aforementioned improvements, a possible Ecodesign calls for an earthing system utilizing single-phase separation transformers installed in the unit, grounded at the mid-point of their secondary side. The introduction of a source of magnetic fields into the premises at the power frequency of 60/50 Hz (i.e. extremely low frequency, ELF) might expose persons to their potential adverse health effects, as well as, sensitive electronic equipment to disturbances. This paper seeks to clarify this matter by evaluating the ELF magnetic fields as produced by the user's own transformer and by other units eventually present in the vicinity

Recognition of Intentional Violations of Active Constraints in Cooperative Manipulation Tasks

Active Constraints (ACs) are high-level control algorithms deployed to assist a human operator in man-machine cooperative tasks [1], and define regions within which it is safe for the robot to move and cut [2]. To enhance the performance in cooperative surgical tasks, adaptive constraints have been exploited to optimally adjust the provided level of assistance according to some knowledge of the task, hardware or user. In [3] Hidden Markov Models were used for the run-time detection of the user intention to leave a guidance constraint to circumvent an obstacle. In this work, we present a novel, Neural Network (NN)-based method for the runtime classification of intentional and unintentional violations of ACs, that is trained on either statistical or frequency features from the enforced constraint forces. We investigate which set of parameters yield faster and more reliable classification results, both for guidance and regional constraints

Effect of State Feedback Coupling and System Delays on the Transient Performance of Stand-Alone VSI with LC Output Filter

The influence of state feedback coupling in the dynamics performance of power converters for stand-alone microgrids is investigated. Computation and PWM delays are the main factors that limit the achievable bandwidth of current regulators in digital implementations. In particular, the performance of state feedback decoupling is degraded because of these delays. Two decoupling techniques to improve the transient response of the system are investigated, named non-ideal and ideal capacitor voltage decoupling respectively. In particular, the latter solution consists in leading the capacitor voltage on the state feedback decoupling path in order to compensate for system delays. Practical implementation issues are discussed with reference to both the decoupling techniques. A design methodology for the voltage loop, that considers the closed loop transfer functions developed for the inner loop, is also provided. A proportional resonant voltage controller is designed according to Nyquist criterion taking into account application requirements. For this purpose, a mathematical expression based on root locus analysis is proposed to find the minimum value of the fundamental resonant gain. Experimental tests performed in accordance to UPS standards verify the theoretical analysis

Liver contrast enhanced ultrasound perfusion imaging in the evaluation of chronic hepatitis C fibrosis: preliminary results

We wanted to determine whether liver contrast-enhanced ultrasound (CEUS)–derived peak signal intensity (PSI) and peak signal intensity/time (PIT) predict liver fibrosis in chronic hepatitis C (CHC). Fortynine patients with CHC (METAVIR classification) and 10 control subjects were included in the study. After a bolus of 2.4 mL SonoVue (Bracco Imaging, Milan, Italy) solution was injected into a peripheral vein, the right lobe of the liver containing the right portal vein was scanned in a transverse section. Two-dimensional sonography was performed using the Philips iU22 ultrasound system (Philips Healthcare, Best, the Netherlands). A 1.0–5.0-MHz (C5-1) wideband convex transducer was used, applying the following settings in all cases. Regions of interest were manually drawn over the right liver lobe and over the portal vein (PV). Liver parenchyma PSI (LPpsi) and PIT (LPpit), portal vein PSI (PVpsi) and PIT (PVpit) were automatically calculated. dPSI was defined as the difference between PVpsi and LPpsi. A significant correlation was observed between PAPSI and fibrosis scores. When patients were stratified according to their LPpsi, a significant difference was achieved only between patients with fibrosis score 0–1 vs. 2–3 and 2 vs. 4. Statistically significant differences between all fibrosis scores, except 0 vs. 1 and 3 vs. 4 were observed when dPSI was used to stratify patients. Overall diagnostic accuracy of LPpsi and dPSI measurement for severe fibrosis by area under the receiving operator characteristic curve analysis was, respectively, 0.87 and 0.88.We suggest that liver CEUS perfusion could have the potential to be used as a complementary tool for the evaluation of liver fibrosis. However, further large-scale studies are required to accurately assess its accuracy in the evaluation of liver fibrosis

GPU-based Real-time Triggering in the NA62 Experiment

Over the last few years the GPGPU (General-Purpose computing on Graphics Processing Units) paradigm represented a remarkable development in the world of computing. Computing for High-Energy Physics is no exception: several works have demonstrated the effectiveness of the integration of GPU-based systems in high level trigger of different experiments. On the other hand the use of GPUs in the low level trigger systems, characterized by stringent real-time constraints, such as tight time budget and high throughput, poses several challenges. In this paper we focus on the low level trigger in the CERN NA62 experiment, investigating the use of real-time computing on GPUs in this synchronous system. Our approach aimed at harvesting the GPU computing power to build in real-time refined physics-related trigger primitives for the RICH detector, as the the knowledge of Cerenkov rings parameters allows to build stringent conditions for data selection at trigger level. Latencies of all components of the trigger chain have been analyzed, pointing out that networking is the most critical one. To keep the latency of data transfer task under control, we devised NaNet, an FPGA-based PCIe Network Interface Card (NIC) with GPUDirect capabilities. For the processing task, we developed specific multiple ring trigger algorithms to leverage the parallel architecture of GPUs and increase the processing throughput to keep up with the high event rate. Results obtained during the first months of 2016 NA62 run are presented and discussed

NaNet: a Low-Latency, Real-Time, Multi-Standard Network Interface Card with GPUDirect Features

While the GPGPU paradigm is widely recognized as an effective approach to high performance computing, its adoption in low-latency, real-time systems is still in its early stages. Although GPUs typically show deterministic behaviour in terms of latency in executing computational kernels as soon as data is available in their internal memories, assessment of real-time features of a standard GPGPU system needs careful characterization of all subsystems along data stream path. The networking subsystem results in being the most critical one in terms of absolute value and fluctuations of its response latency. Our envisioned solution to this issue is NaNet, a FPGA-based PCIe Network Interface Card (NIC) design featuring a configurable and extensible set of network channels with direct access through GPUDirect to NVIDIA Fermi/Kepler GPU memories. NaNet design currently supports both standard - GbE (1000BASE-T) and 10GbE (10Base-R) - and custom - 34~Gbps APElink and 2.5~Gbps deterministic latency KM3link - channels, but its modularity allows for a straightforward inclusion of other link technologies. To avoid host OS intervention on data stream and remove a possible source of jitter, the design includes a network/transport layer offload module with cycle-accurate, upper-bound latency, supporting UDP, KM3link Time Division Multiplexing and APElink protocols. After NaNet architecture description and its latency/bandwidth characterization for all supported links, two real world use cases will be presented: the GPU-based low level trigger for the RICH detector in the NA62 experiment at CERN and the on-/off-shore data link for KM3 underwater neutrino telescope

Current control loop design and analysis based on resonant regulators for microgrid applications

Voltage and current control loops play an important role in the performance of microgrids employing power electronics voltage source inverters. Correct design of feedback loops is essential for the proper operation of these systems. This paper analyzes the influence of state feedback cross-coupling in the design of resonant regulators for inner current loops in power converters operating in standalone microgrids. It is also demonstrated that the effect of state feedback cross-coupling degrades the performance of the control loops by increasing the steady-state error. Different resonant regulators structures are analyzed and compared, performing experimental tests to validate the results of the theoretical analysis

Static and dynamic evaluation of pelvic floor disorders with an open low-field tilting magnet.

AIM: To assess the feasibility of magnetic resonance defaecography (MRD) in pelvic floor disorders using an open tilting magnet with a 0.25 T static field and to compare the results obtained from the same patient both in supine and orthostatic positions. MATERIALS AND METHODS: From May 2010 to November 2011, 49 symptomatic female subjects (mean age 43.5 years) were enrolled. All the patients underwent MRD in the supine and orthostatic positions using three-dimensional (3D) hybrid contrast-enhanced (HYCE) sequences and dynamic gradient echo (GE) T1-weighted sequences. All the patients underwent conventional defaecography (CD) to correlate both results. Two radiologists evaluated the examinations; inter and intra-observer concordance was measured. The results obtained in the two positions were compared between them and with CD. RESULTS: The comparison between CD and MRD found statistically significant differences in the evaluation of anterior and posterior rectocoele during defaecation in both positions and of rectal prolapse under the pubo-coccygeal line (PCL) during evacuation, only in the supine position (versus MRD orthostatic: rectal prolapse p < 0.0001; anterior rectocoele p < 0.001; posterior rectocoele p = 0.008; versus CD: rectal prolapse p < 0.0001; anterior rectocoele p < 0.001; posterior rectocoele p = 0.01). The value of intra-observer intra-class correlation coefficient (ICC) ranged from good to excellent; the interobserver ICC from moderate to excellent. CONCLUSION: MRD is feasible with an open low-field tilting magnet, and it is more accurate in the orthostatic position than in the supine position to evaluate pelvic floor disorders

Beneficial autoimmunity at body surfaces – immune surveillance and rapid type 2 immunity regulate tissue homeostasis and cancer

Epithelial cells line body surface tissues and provide a physicochemical barrier to the external environment. Frequent microbial and non-microbial challenges such as those imposed by mechanical disruption, injury or exposure to noxious environmental substances including chemicals, carcinogens, ultraviolet-irradiation or toxins cause activation of epithelial cells with release of cytokines and chemokines as well as alterations in the expression of cell surface ligands. Such display of epithelial stress is rapidly sensed by tissue resident immunocytes, which can directly interact with self-moieties on epithelial cells and initiate both local and systemic immune responses. Epithelial cells are thus key drivers of immune surveillance at body surface tissues. However, epithelial cells have a propensity to drive type 2 immunity (rather than type 1) upon non-invasive challenge or stress – a type of immunity whose regulation and function still remain enigmatic. Here we review the induction and possible role of type 2 immunity in epithelial tissues and propose that rapid immune surveillance and type 2 immunity are key regulators of tissue homeostasis and carcinogenesis

Position-sensorless control of permanent-magnet-assisted synchronous reluctance motor

The sensorless control of permanent-magnet-assisted synchronous reluctance (PMASR) motors is investigated, in order to conjugate the advantages of the sensorless control with full exploitation of the allowed operating area, for a given inverter. An additional pulsating flux is injected in the d-axis direction at low and zero speed, while it is dropped out, at large speed, to save voltage and additional loss. A flux-observer-based control scheme is used, which includes an accurate knowledge of the motor magnetic behavior. This leads, in general, to good robustness against load variations, by counteracting the magnetic cross saturation effect. Moreover, it allows an easy and effective correspondence between the wanted torque and flux and the set values of the chosen control variables, that is d-axis flux and q-axis current. Experimental verification of the proposed method is given, both steady-state and dynamic performance are outlined. A prototype PMASR motor will be used to this aim, as part of a purposely assembled prototype drive, for light traction application (electric scooter