Oscillation threshold of a clarinet model: a numerical continuation approach

This paper focuses on the oscillation threshold of single reed instruments. Several characteristics such as blowing pressure at threshold, regime selection, and playing frequency are known to change radically when taking into account the reed dynamics and the flow induced by the reed motion. Previous works have shown interesting tendencies, using analytical expressions with simplified models. In the present study, a more elaborated physical model is considered. The influence of several parameters, depending on the reed properties, the design of the instrument or the control operated by the player, are studied. Previous results on the influence of the reed resonance frequency are confirmed. New results concerning the simultaneous influence of two model parameters on oscillation threshold, regime selection and playing frequency are presented and discussed. The authors use a numerical continuation approach. Numerical continuation consists in following a given solution of a set of equations when a parameter varies. Considering the instrument as a dynamical system, the oscillation threshold problem is formulated as a path following of Hopf bifurcations, generalizing the usual approach of the characteristic equation, as used in previous works. The proposed numerical approach proves to be useful for the study of musical instruments. It is complementary to analytical analysis and direct time-domain or frequency-domain simulations since it allows to derive information that is hardly reachable through simulation, without the approximations needed for analytical approach

Thermal and Performance Efficient On-Chip Surface-Wave Communication for Many-Core Systems in Dark Silicon Era

Due to the exceedingly high integration density of VLSI circuits and the resulting high power density, thermal integrity became a major challenge. One way to tackle this problem is Dark silicon. Dark silicon is the amount of circuitry in a chip that is forced to switch off to insure thermal integrity of the system and prevent permanent thermal-related faults. In many-core systems, the presence of Dark Silicon adds new design constraints, in general, and on the communication fabric of such systems, in particular. This is due to the fact that system-level thermal-management systems tend to increase the distance between high activity cores to insure better thermal balancing and integrity. Consequently, a designing dilemma is created where a compromise has to be made between interconnect performance and power consumption. This study proposes a hybrid wire and surface-wave interconnect (SWI) based Network-on-Chip (NoC) to address the dark silicon challenge. Through efficient utilization of one-hop cross the chip communication SWI links, the proposed architecture is able to offer an efficient and scalable communication platform in terms of performance, power, and thermal impact. As a result, evaluations of the proposed architecture compared to baseline architecture under dark silicon scenarios show reduction in maximum temperature by 15°C, average delay up to 73.1%, and energy-saving up to ~3X. This study explores the promising potential of the proposed architecture in extending the utilization wall for current and future many-core systems in dark silicon era

Comparative analysis of computer-vision and BLE technology based indoor navigation systems for people with visual impairments

Background: Considerable number of indoor navigation systems has been proposed to augment people with visual impairments (VI) about their surroundings. These systems leverage several technologies, such as computer-vision, Bluetooth low energy (BLE), and other techniques to estimate the position of a user in indoor areas. Computer-vision based systems use several techniques including matching pictures, classifying captured images, recognizing visual objects or visual markers. BLE based system utilizes BLE beacons attached in the indoor areas as the source of the radio frequency signal to localize the position of the user. Methods: In this paper, we examine the performance and usability of two computer-vision based systems and BLE-based system. The first system is computer-vision based system, called CamNav that uses a trained deep learning model to recognize locations, and the second system, called QRNav, that utilizes visual markers (QR codes) to determine locations. A field test with 10 blindfolded users has been conducted while using the three navigation systems. Results: The obtained results from navigation experiment and feedback from blindfolded users show that QRNav and CamNav system is more efficient than BLE based system in terms of accuracy and usability. The error occurred in BLE based application is more than 30% compared to computer vision based systems including CamNav and QRNav. Conclusions: The developed navigation systems are able to provide reliable assistance for the participants during real time experiments. Some of the participants took minimal external assistance while moving through the junctions in the corridor areas. Computer vision technology demonstrated its superiority over BLE technology in assistive systems for people with visual impairments. - 2019 The Author(s).Scopu

Network on Chip Optimization Based on Surrogate Model Assisted Evolutionary Algorithms

Network-on-Chip (NoC) design is attracting more and more attention nowadays, but there is a lack of design optimization method due to the computationally very expensive simulations of NoC. To address this problem, an algorithm, called NoC design optimization based on Gaussian process model assisted differential evolution (NDPAD), is presented. Using the surrogate model-aware evolutionary search (SMAS) framework with the tournament selection based constraint handling method, NDPAD can obtain satisfactory solutions using a limited number of expensive simulations. The evolutionary search strategies and training data selection methods are then investigated to handle integer design parameters in NoC design optimization problems. Comparison shows that comparable or even better design solutions can be obtained compared to standard EAs, and much less computation effort is needed

Factors Affecting Hemodialysis Patients' Satisfaction with Their Dialysis Therapy

Aim. To assess the degree of satisfaction among hemodialysis patients and the factors influencing this satisfaction. Methods. Patients were recruited from 3 Saudi dialysis centers. Demographic data was collected. Using 1 to 10 Likert scale, the patients were asked to rate the overall satisfaction with, and the overall impact of, their dialysis therapy on their lives and to rate the effect of the dialysis therapy on 15 qualities of life domains. Results. 322 patients were recruited (72.6% of the total eligible patients). The mean age was 51.7 years (±15.4); 58% have been on dialysis for >3 years. The mean Charlson Comorbidity Index was 3.2 (±2), and Kt/V was 1.3 (±0.44). The mean satisfaction score was (7.41 ± 2.75) and the mean score of the impact of the dialysis on the patients' lives was 5.32 ± 2.55. Male patients reported worse effect of dialysis on family life, social life, energy, and appetite. Longer period since the commencement of dialysis was associated with adverse effect on finances and energy. Lower level of education was associated with worse dialysis effect on stress, overall health, sexual life, hobbies, and exercise ability. Conclusion. The level of satisfaction is affected by gender, duration on dialysis, educational level, and standard of care given

Synthesis, characterization, molecular docking studies and biological activity of coumarin linked 2-pyridone heterocycles

231-237In the present paper, the synthesis, characterization, antimicrobial activity and in silico molecular docking study of 6-((arylidene)amino)-4-(4-chlorophenyl)-2-oxo-1-((1-(2-oxo-2H-chromen-3-yl)ethylidene)amino)-1,2-dihydropyridine-3,5-dicarbonitriles 4a-o have been reported. Compounds 4d, 4g, 4j, 4k, 4m and 4o show significant activity. Structure determination of the synthesized compounds has been done by the standard spectroscopic techniques. It is observed that biological activity is influenced by electronic environment of the molecules. Electron withdrawing group at para position plays a major role for enhancing the biological activity for antibacterial activity and the electron donating group at para position for antifungal activity. Compounds 4a-o have been further evaluated for cytotoxicity on HeLa cells. From the cytotoxicity results, compounds have been found to possess low cytotoxicity with potent antimicrobial activity

Synthesis, characterization, molecular docking studies and biological activity ofcoumarin linked 2-pyridone heterocycles

In the present paper, the synthesis, characterization, antimicrobial activity and in silico molecular docking study of6-((arylidene)amino)-4-(4-chlorophenyl)-2-oxo-1-((1-(2-oxo-2H-chromen-3-yl)ethylidene)amino)-1,2-dihydropyridine-3,5-dicarbonitriles 4a-o have been reported. Compounds 4d, 4g, 4j, 4k, 4m and 4o show significant activity. Structuredetermination of the synthesized compounds has been done by the standard spectroscopic techniques. It is observed thatbiological activity is influenced by electronic environment of the molecules. Electron withdrawing group at para positionplays a major role for enhancing the biological activity for antibacterial activity and the electron donating group at paraposition for antifungal activity. Compounds 4a-o have been further evaluated for cytotoxicity on HeLa cells. From thecytotoxicity results, compounds have been found to possess low cytotoxicity with potent antimicrobial activity

Idealized digital models for conical reed instruments, with focus on the internal pressure waveform

International audienceTwo models for the generation of self-oscillations of reed conical woodwinds are presented. They use the fewest parameters (of either the resonator or the ex-citer), whose influence can be quickly explored. The formulation extends iterated maps obtained for loss-less cylindrical pipes without reed dynamics. It uses spherical wave variables in idealized resonators, with one parameter more than for cylinders: the missing length of the cone. The mouthpiece volume equals that of the missing part of the cone, and is implemented as either a cylindrical pipe (first model) or a lumped element (second model). Only the first model adds a length parameter for the mouthpiece and leads to the solving of an implicit equation. For the second model, any shape of nonlinear characteristic can be directly considered. The complex characteristics impedance for spherical waves requires sampling times smaller than a round trip in the resonator. The convergence of the two models is shown when the length of the cylindrical mouthpiece tends to zero. The waveform is in semi-quantitative agreement with experiment. It is concluded that the oscillations of the positive episode of the mouthpiece pressure are related to the length of the missing part, not to the reed dynamics

NectarCAM : a camera for the medium size telescopes of the Cherenkov Telescope Array

NectarCAM is a camera proposed for the medium-sized telescopes of the Cherenkov Telescope Array (CTA) covering the central energy range of ~100 GeV to ~30 TeV. It has a modular design and is based on the NECTAr chip, at the heart of which is a GHz sampling Switched Capacitor Array and a 12-bit Analog to Digital converter. The camera will be equipped with 265 7-photomultiplier modules, covering a field of view of 8 degrees. Each module includes the photomultiplier bases, high voltage supply, pre-amplifier, trigger, readout and Ethernet transceiver. The recorded events last between a few nanoseconds and tens of nanoseconds. The camera trigger will be flexible so as to minimize the read-out dead-time of the NECTAr chips. NectarCAM is designed to sustain a data rate of more than 4 kHz with less than 5\% dead time. The camera concept, the design and tests of the various subcomponents and results of thermal and electrical prototypes are presented. The design includes the mechanical structure, cooling of the electronics, read-out, clock distribution, slow control, data-acquisition, triggering, monitoring and services.Comment: In Proceedings of the 34th International Cosmic Ray Conference (ICRC2015), The Hague, The Netherlands. All CTA contributions at arXiv:1508.0589