Parameters Duty Cycle Research Articles

DM-CSAT: a LTE-U/Wi-Fi coexistence solution based on reinforcement learning

Recent literature demonstrated promising results of Long-Term Evolution (LTE) deployments over unlicensed bands when coexisting with Wi-Fi networks via the Duty-Cycle (DC) approach. However, it is known that performance in coexistence is strongly dependent on traffic patterns and on the duty-cycle ON–OFF rate of LTE. Most DC solutions rely on static coexistence parameters configuration, hence real-life performance in dynamically varying scenarios might be affected. Advanced reinforcement learning techniques may be used to adjust DC parameters towards efficient coexistence, and we propose a Q-learning Carrier-Sensing Adaptive Transmission mechanism which adapts LTE duty-cycle ON–OFF time ratio to the transmitted data rate, aiming at maximizing the Wi-Fi and LTE-Unlicensed (LTE-U) aggregated throughput. The problem is formulated as a Markov decision process, and the Q-learning solution for finding the best LTE-U ON–OFF time ratio is based on the Bellman’s equation. We evaluate the performance of the proposed solution for different traffic load scenarios using the ns-3 simulator. Results demonstrate the benefits from the adaptability to changing circumstances of the proposed method in terms of Wi-Fi/LTE aggregated throughput, as well as achieving a fair coexistence.

A Spur-Reduction DC–DC Converter With Active Ripple Cancelation Technique

This paper presents an active ripple cancelation (ARC) technique for reducing the switching harmonics of the output voltage of a dc–dc converter. An ARC module injects an ac current to accurately cancel the inductor current ripple while the switching converter provides the dc output current. As a result, the output spur of the switching converter can be reduced effectively. However, due to the ARC module, the proposed power converter includes two complex poles. To ensure the system stability and achieve accurate ripple cancelation, a proposed control method and an adaptive phase-lock circuit are utilized. Furthermore, the ripple cancelation capability is independent of duty cycle, load current, and other converter parameters. The measurement results demonstrate that the switching spur reduction with ARC technique can achieve 28 dB while the noise floor is kept the same.

THE RESEARCH OF PULSE SIGNAL PARAMETER MEASURING INSTRUMENT BASED ON FPGA AND STM32

Using the principle of measurement accuracy, combined with EDA technology and microcomputer control technology,we designed the pulse signal measuring instrument. The accuracy of frequency the measurement method not only has highmeasurement accuracy, butalso in the frequency measurement accuracy of the frequency bandwidth can be keptconstant.As a result of the front-end circuit and good isolation circuit and other technical measures, and In a wide rangeof frequencies in the range of frequency and amplitude, period, duty cycle and other parameters were measuredaccurately, and can be preset by adjusting the gate time measurement accuracy. After experimental verification and datameasurement, results show that our scheme is feasible and can achieve highermeasurement accuracy in a widebandwidth.

Formation and characterization of the vortices generated by a DBD plasma actuator in burst mode

The present study reports the formation and evolution characteristics of the continuously generated vortical structure and resulting flow field in quiescent air induced by a dielectric-barrier-discharge (DBD) plasma actuator in burst mode operation. A starting vortex is formed during the initial actuation period, which disappears after a small time interval for continuous mode operation of the DBD plasma actuator. A burst input signal to the actuator generates a train of self-similar vortices. The behaviour of vortices and the average flow field induced by the actuator has been studied using high speed schlieren visualization and particle image velocimetry technique for different actuation amplitude and duty cycle parameters. These repeating vortices travel faster than the starting vortex, and the vortex core velocity of these repeating vortices increases with increase in duty cycle parameter. Fuller u-velocity profile, higher v-velocity near the edge of the outer shear layer region, and higher growth of the wall jet thickness is observed due to enhanced entrainment by repeating vortices for burst mode operation. The repeating vortices travel at an angle of 21° relative to the wall surface for duty cycle parameter of 90.9% in comparison to 31° for the starting vortex. Self-similarity of the velocity profile is delayed in the streamwise direction for burst mode operation in comparison to that for the continuous mode of operation. This can be attributed to delay in attaining the maximum velocity of the wall jet profile and presence of coherent structures for the burst mode operation. The non-dimensional vortex core location and size for repeating vortices follow power law fit similar to the starting vortex with difference in value of the power law exponent. The phase difference between the input voltage and current drawn is in the range of π12 to π9 (in radians) for both continuous and burst mode operation indicating identical electrical behaviour of the actuator in both modes of operation. Overall, the present study illustrates the effectiveness of a DBD plasma actuator as a vortex generator while operating in the burst mode. The train of vortices generated during the burst mode operation shows overall similarity with the starting vortex, and the difference in behavior is attributed to the interaction between the vortices shed during consecutive bursting cycle, which is a function of the duty cycle parameter.

PWM Algorithms Synthesis

The paper describes various modified algorithms of classical sinusoidal pulse width modulation (PWM) serving for a three-phase two-level inverter control. The paper presents the results of a research of 3 PWM versions with varying duty cycle parameters and frequency of the pulse signal modulation. The method is to divide the modulated sinusoidal signal cycle (half-cycle) into intervals in order to change the modulation frequency within the separate sectors of forming the quasi-sinusoidal output voltage waves. In addition, algorithmic ways to compensate the additional losses in the inverter and the induction motor at high modulation frequencies of a discrete control signal are investigated and described in the paper. Calculations and simulations are performed by NI Multisim simulation program and NI LabVIEW visual programming environment. Theoretical studies are performed using the electric drive theories, discrete control systems and spectral analysis. The practical implementation performed by Texas Instruments Stellaris Launchpad using the Energia prototyping platform, field-programmable gate arrays (FPGA) of National Instruments CompactRIO-9074 and NI Single-Board RIO GPIC (sbRIO-9606, NI 9683 (GPIC), LX45 FPGA) using NI LabVIEW software and add-on modules (LabVIEW Real Time, LabVIEW FPGA). The suggested inverter control methods make it possible to reduce the distortion of the output quasi-sinusoidal signal and reduce the power consumption of the DC link while significantly reducing the number of inverter transistor switching in comparison with the classical method without premodulation or technical devices (filter-compensating devices).

Оценка показателей рабочего цикла HCCI-двигателя с наддувом при различных частотах вращения коленчатого вала и нагрузках

Оценка показателей рабочего цикла HCCI-двигателя с наддувом при различных частотах вращения коленчатого вала и нагрузках

Analysis and optimization of duty-cycle in preamble-based random access networks

Duty-cycling has been proposed as an effective mechanism for reducing the energy consumption in wireless sensor networks (WSNs). Asynchronous duty-cycle protocols where the receiver wakes up periodically to check whether there is a transmission and the sender transmits preambles to check if the receiver is awake are widely used in WSNs due to the elimination of complex control mechanisms for topology discovery and synchronization. However, the intrinsic simplicity of the asynchronous mechanism has the drawback of smaller energy saving potential that requires the optimization of the duty cycle parameters. In this paper, we propose a novel method for the optimization of the duty-cycle parameters in preamble-based random access networks based on the accurate modeling of delay, reliability and energy consumption as a function of listen time, sleep time, traffic rate and medium access control (MAC) protocol parameters. The challenges for modeling are the random access MAC and the sleep policy of the receivers, which make it impossible to determine the exact time of data packet transmissions, and thus difficult to investigate the performance indicators given by the delay, reliability and energy consumption to successfully receive packets. An analysis of these indicators is developed as a function of the relevant parameters of the network and it is used in the minimization of the energy consumption subject to delay and reliability requirements. The optimization provides significant reduction of the energy consumption compared to the previously proposed protocols in the literature.

Parametric study of vortex train generated by plasma actuator in dependency on input voltage waveform

This article is based on previous work of authors. The vortex train is created by a plasma DBD actuator after application of low-frequency amplitude modulation on high-frequency high-voltage carrier waveform. Data acquisition of flow field around actuators will be performed using time-resolved PIV measurement technique in plane parallel to flow and in cross-section. Phase-averaging will be used due to pseudo-periodical character of this process. The vortex behaviour dependency on modulation frequency, duty cycle, voltage value, electrode gap and other parameters will be shown. The generated flow patterns are to be applied for control of a boundary layer.

SU-E-T-493: 4D Considerations for Active-Scanning Proton Beams

Purpose: To optimize delivery parameters for mobile targets treated with active-scanning proton beams. Methods: An algorithm was developed to sort delivery of scanned proton plans into temporal bins. The binning reflects various dose rates and respiratory periods. A single-field proton plan was generated to treat a target within a phantom. The delivery of the plan was sorted into temporal bins, and the bins were displaced spatially to simulate residual motion within a respiratory gated delivery. The binned delivery was repeated multiple times with random starting points. Weighted combinations of the varied start points were formed to simulate repainting as a means of neutralizing intra-gate motion. This process was extended to a plan generated for a single phase of a 4DCT scan of a lung tumor. Intra-gate motion was simulated by binning the delivery and calculating portions on neighboring 4DCT phases. The dose matrices were deformably remapped back onto the planned 4DCT phase and the matrices were summed to yield the delivered dose. As with the phantom plan, various ranges of motion and repainting were simulated.Results: Simulated motion of a phantom tumor volume yields shallower DVH fall off than a static displacement of the same magnitude, although both hot and cold spots are observed. Simulated repaintings of the volume mitigated coverage inhomogeneities. Because of lower density tissue surrounding the lung tumor, simulated intra-gate motion results in a reduction of dose to the tumor. Conclusions: By varying the range of simulated motion and number of repaintings we will optimize duty cycle and delivery parameters for scanning proton treatment of a mobile tumor. J Kruse is supported in part by a grant from Varian Medical Systems, Inc.

Tribological Study of TiN Nano Structured Films Deposited on Plasma Nitrided H11 Steel by Pulsed DC PACVD

In recent years, plasma-assisted chemical vapor deposition (PACVD) has been introduced as a suitable technique to deposit hard coatings on to tools of complex geometries. This study focuses on the influence of process parameters during plasma nitriding and TiN coatings, such as duty cycle, treatment time and temperature parameters on the properties of nanostructured binary layers. To improve performance and the quality of the samples, a duplex process combining a plasma nitriding (PN) pre-treatment and a plasma-assisted chemical vapour deposition (PACVD) was applied on the steel surface. A mixture of H2, N2, Ar and TiCl4 was used to deposit a thin film of TiN on H11 steel. The microstructural, mechanical and tribological properties of the coating were investigated using X-Ray diffraction, scanning electron microscopy, atomic force microscopy combined with nanoindentation and pin-on-disc measurements. The results indicate that the small grain size was obtained at low duty cycle (33%) and increased with increasing of the duty cycle to 60 %. Calculated roughness of surface for duty cycle 50 % was 72 nm.

Bucket wheel failure caused by residual stresses in welded joints

Cracks in the welded joints on the bucket wheel (BW) body of the bucket wheel excavator (BWE) SRs 1300 were discovered after merely 1800 h of operation. Investigations are carried out in order to detect the causes of cracks occurrence and thus prevent possible heavy damages to the machine. Working stresses in the BW body are defined by using FEM. Methods of strain gauges are used for the experimental stress analysis in real working conditions. Measurements of welding residual stresses are carried out by applying the centre hole drilling method. Additionally, experimental investigations defined the chemical composition, tensile properties, hardness, impact toughness, as well as the susceptibility to cracking (measurement of residual hydrogen, FISCO, Tekken and CTS methods). External loads induced by the resistance-to-excavation are determined by following a model that encompasses all relevant structural parameters and also the BWE duty cycle parameters. By using FEM, it was identified that the maximum values of equivalent stress in the zones of cracks occurrence are lower than the allowable values. This conclusion is confirmed by measurements. The measured values of welding residual stresses reach the value of yield strength in critical zones. Non-compliances during grooving (clearance in the root is substantially larger than the prescribed one) caused large filler material deposition and heat input. Such welded joints are susceptible to cold cracking. Based on the results of the numerical–experimental analysis, findings show that in critical zones the combination of working (dynamic) and residual (static) stress can be above the limit lines of modified Goodman’s diagrams i.e. that the fatigue safety of the BW body structure was insufficient.

Low temperature ITO thin film deposition on PES substrate using pulse magnetron sputtering

Experiments were conducted using pulse magnetron sputtering (PMS) to deposit transparent conducting indium tin oxide (ITO) thin film onto flexible polyethersulfone (PES) plastic substrates. The thin film microstructure, optoelectronic and residual stress were analyzed using the modulating PMS power, work pressure, pulse frequency, duty cycle and cycle time process parameters. The residual stress of the thin film was determined by scanning electron microscopy (SEM) combined with the Sony equation. The experimental results show that PMS has a lower process temperature, higher deposition rate and lower resistivity compared with the radio frequency process at the same output power. The duty cycle increase produces the optimum optoelectronic characteristics. When the pressure, power, duty cycle and sputter time are increased, the thin film stress will also increase, causing flexural distortion in the PES plastic substrate. When the deposition thickness reaches 1.5 μm, ITO thin film will appear with a distinct split. Under 5 mtorr work pressure, 60 W power, 33 μs duty time and 2 μs pulse reverse time at duty cycle 95%, thin film with an optimized electrical 3.0 × 10 −4 Ω-cm, RMS surface roughness of 0.85 nm and visible region optical transmittance will be achieved with acquisition of over 85%.

Refining Histotripsy: Defining the Parameter Space for the Creation of Nonthermal Lesions With High Intensity, Pulsed Focused Ultrasound of the In Vitro Kidney

Focused ultrasound therapy is a promising modality for noninvasive tissue ablation. However, the relative contributions of thermal and cavitational effects are poorly defined. We characterized the ultrasound parameters within which tissue ablation occurs by cavitational mechanisms without significant thermal effect. In vitro porcine kidneys were submerged in degassed water. Tissue ablation was performed by delivering ultrasound (750 kHz and 20 microsecond pulses) of constant spatial peak energy dose (100 J/cm(2)) to adjacent foci in a 3 x 3 grid configuration. For each ablation different intensity (0.11 to 211 kW/cm(2)) and duty cycle (0.04% to 100%) parameters were selected. A thermocouple co-localized with the center of each grid continuously measured temperature. Following ablation each kidney was examined grossly and histologically. Ablated tissue lesions were classified into 4 discrete morphological categories, including blanched--firm, pale, desiccated tissue, disrupted--a cavity containing thin, isochromatic liquid, mixed--a cavity containing pale, thick liquid with minimal blanching and no grossly visible effect. Morphologically similar lesions clustered at separable regions of the ultrasound parameter space. The maximal temperature attained in disrupted lesions was similar to that attained when there was no effect (44.2C and 47.2C, respectively, p = 0.31), although it was significantly lower than the maximal temperatures for desiccated or mixed lesions (67.5C and 59.4C, each p <0.0001). In an in vitro model we defined the ultrasound parameter region within which purely cavitational ablation of tissue is possible with a negligible thermal component. Additional research is needed to optimize the parameters for in vivo cavitational tissue ablation, incorporating the influence of tissue perfusion.

Analysis, simulation, and evaluation of scrolling illumination as a method for reducing motion blur in LCOS projectors

Abstract— A high‐fidelity simulation of motion blurring in an LCOS projector was developed by using the measured temporal response of the projector. The simulation was validated for continuous and scanning illumination by comparison with results of motion‐blur measurements by using a pursuit camera. The simulation was then used to analyze and optimize duty cycle and phase parameters for scrolling illumination in the general case.

Barometric whole body plethysmography in mice

There has been significant utilization of the technique described by Hamelmann et al. ( Am J Respir Crit Care Med 156: 766–775, 1997) in which a parameter, enhanced pause (Penh), related to airways responsiveness is noninvasively measured by unrestrained plethysmography (UP). Investigating this technique, we sought to answer these questions: 1) How do changes in Penh compare with changes in traditional plethysmographic and lung mechanical parameters? 2) How do UP parameters perform in two different mouse strains? Awake immunized and control BALB/c ( n = 16) and C57BL/6 ( n = 14) mice were placed in the UP chamber and exposed to doses of aerosolized methacholine while the following parameters were measured at each concentration: inspiratory time (Ti), expiratory time (Te), total time (Ttot), Ti/Ttot, peak inspiratory pressure, peak expiratory pressure, Pause, Penh, tidal volume (Vt), Vt/Ti, Vt/Te, and Vt/Ttot. The next day, lung resistance (Rl) and compliance (Cl) were invasively measured in the same animals. For the BALB/c, the parameters with the highest magnitude of correlation coefficient vs. Rl are (in order) 1) Cl, 2) Pause and Penh, 3) parameters of breathing frequency (Te, Ttot, Ti), and 4) parameters related to Vt (inspiratory pressure, expiratory pressure). Flow parameters (Vt/Ttot, Vt/Te, Vt/Ti) and duty cycle parameters (Ti/Ttot) had insignificant correlations. This ordering is significantly different in C57BL/6 mice, in which the parameters with the largest correlations are 1) Cl, 2) parameters of breathing frequency, and 3) flow parameters. Pause, Penh, Vt, and duty cycle parameters had insignificant correlations. These data show that Penh is problematic in the sense that it is strain specific; it behaves very differently in BALB/c and C57BL/6 mice. We suggest that UP parameters largely originate as part of reflex control of breathing processes, rather than in the lung mechanics and conclude that it is inappropriate to use UP parameters in general, and Penh specifically, as substitute variables for invasive mechanical indexes such as Rl.

In Situ, Time-Resolved Normal Incidence Reflectance Spectroscopy of Polycrystalline Platinum Microelectrodes in Aqueous Electrolytes

In situ normal incidence reflectance spectra of polycrystalline Pt microelectrodes have been monitored as a function of the applied potential in aqueous 0.5 M H(2)SO(4) using a He-Ne laser source (633 nm) and a beam splitter/microscope objective arrangement. Data recorded during voltammetric cycles in Ar-purged solutions revealed a linear correlation between the normalized change in reflectance, DeltaR/R = (R(s) - R(ref))/R(ref) (where R(s) and R(ref) are the light intensities measured by the detector at the sampling, s, and reference potentials, ref, respectively), and the extent of oxidation of the Pt surface over a wide coverage range. Reflectance spectra were also collected in CO-saturated 0.5 M H(2)SO(4) during chronocoulometric measurements involving judiciously selected limits for both the potential step and duty cycle parameters. Analysis of these results made it possible to extract contributions to the current derived from oxide formation during oxidation of adsorbed and bulk CO, based strictly on the optical response.

Monomolecular Functionalization of Pulsed Plasma Deposited Poly(2-hydroxyethyl methacrylate) Surfaces

A combination of X-ray photoelectron, infrared, and nuclear magnetic resonance spectroscopies have shown that pulsed plasma polymerization of 2-hydroxyethyl methacrylate (HEMA) leads to the deposition of structurally well-defined poly(HEMA) films. The molecular weight and surface hydroxyl density of these plasma polymer layers can be controlled by varying the electrical discharge pulse duty cycle parameters. These films are found to display hydrogel behavior, and the surface hydroxyl groups readily undergo reaction with diethylchlorophosphite. The latter is shown to be a useful way of coordinating catalytic rhodium complexes to solid surfaces.

Controlled Attachment of PAMAM Dendrimers to Solid Surfaces

Amine-terminated polyamidoamine (PAMAM) dendrimers can be immobilized onto anhydride-functionalized pulsed plasma polymer surfaces via amide linkage formation. The packing density of dendrimers at the surface can be tailored by programming the pulse duty cycle parameters during plasma polymerization. These PAMAM dendrimer layers are shown to be useful for a variety of surface-related phenomena, for example, fluorination, adhesion, and gas barrier enhancement.

Electroglottographic, aerodynamic, and acoustic study of normal and breathy phonation

A series of experiments were conducted to delineate relationships between voice fundamental frequency (f0), vocal duty cycle (closure/f0 period), amount of unmodulated air flow (air leakage), and acoustic intensity during normal and breathy phonation of the vowel /ɑ/. The f0 and duty cycle parameters were extracted from the electroglottographic signal; the air flow was measured with a Rothenberg‐type pneumotachograph. In order to control the parameters they were displayed graphically during data collection from five normal adult speakers. The results revealed: (1) a positive relationship between vocal duty cycle and acoustic intensity, and between air leakage and acoustic intensity, (2) an inverse relationship between vocal duty cycle and air leakage, (3) a reduction of the maximum duty cycle in the periphery of the speaker's f0 range, (4) speaker‐specific phonatory control. Findings support the notion that the vocal tract is more weakly and less efficiently excited during breathy than normal phonation. [Work supported by the National Institute of Handicapped Research and the Gallaudet Research Institute.]