Changes In Duty Cycle Research Articles

Abstract 17253: Chest Compression Hemodynamics are Dependent on Chest Compression Rate

Introduction: The mechanisms through which chest compressions (CC) generate blood flow remain controversial. The thoracic pump model is CC rate insensitive in the range 60 - 150 compressions per minute (cpm) but is sensitive to change in CC duty cycle with the prediction that increasing duty cycle would result in a modest, but linear, decrease in minute blood flow at a constant rate. Thus, the recently reported relationship between CC rate and outcomes may be due to changes in duty cycle instead of changes in rate. Methods: CPR was performed on nine domestic swine (∼30 Kg) using standard physiological monitoring. Flow was measured in the abdominal aorta, the inferior vena cava (IVC), the right renal artery and vein, the right common carotid and external jugular. Ventricular fibrillation (VF) was electrically induced. Mechanical CC were started after ten minutes of VF. CC were delivered at a rate of 50, 75, 100, 125, or 150 cpm and at a depth of 2” for a total of 54 min. CC rates were changed every 2 min and were randomized. The compression time was held constant at 350 ms. Results: CC generated blood flow showed a significant rate/duty cycle dependence and time dependence in all measured blood vessels. Early in the resuscitation, blood flows were optimized by rates above 100 cpm. As CC continued both the net blood flow and the optimal CC rate decreased as shown in Figure 1. Using previously collected data at 100 cpm and varying duty cycles, we found that minute blood flow did not decrease linearly with duty cycle, as predicted by the thoracic pump model. Conclusions: The optimal CC rate during CPR changes as a function of time suggesting that a fixed CC rate is not optimal. However, the data support the choice of ∼100 cpm as the “best” choice for a fixed CC rate. While some aspects of the observed rate effect may be explained by changes in CC duty cycle, these data do not support the idea that CC generated blood flow is independent of rate in the range 60-150 cpm.

DEVELOPMENT OF AN AUTONOMOUS NAVIGATION AGRICULTURAL ROBOTIC PLATFORM BASED ON MACHINE VISION

In Egypt, management of crops still away from what is being used today by utilizing the advances of mechanical design capabilities, sensing and electronics technology. These technologies have been introduced in many places and recorded high accuracy in different field operations. So, an autonomous agricultural robotic platform (ARP) based on machine vision has been developed and constructed. The ARP consisted of two main parts namely; 1) Power transmission and auto-guide system; and 2) Robotic platform. The experiments were carried out at department of agricultural engineering, faculty of agriculture, Kafrelsheikh University during 2014-2015. In this study, the experiments were conducted in laboratory to optimize the accuracy of ARP control using machine vision in term of the autonomous navigation and performance of the robot’s guidance system. For evaluation the image processing technique, four different camera resolutions (1080×1920, 1944×2592, 2736×3648, and 3240×4320 pixels) and three camera' heights (500, 700 and 1000 mm) have been used to measure the execution time for image processing steps. Flight time of spray droplets has been calculated under three levels of spray height, (70, 100 and 130 mm), three levels of spray pressure (1, 3 and 5 bar) and three levels of nozzle size, (1.5, 3 and 5 mm). Also, the effect of changing duty cycle percentage (DC, %) has been studied to control the speed of the ARP with Pulse Width Modulation (PWM) signals. Different nozzle tip sizes and spray pressures have been used to trace the flow rate variation. Based on the total time consumed in the execution time and droplets flight time, speed of the ARP has been noted according to the resolution of camera and its height levels. Results showed that the robotic platform' guidance system with machine vision was able to adequately distinguish the path, resist image noise and give less lateral offset error than the human operators.The average lateral error of autonomous was 2.75, 19.33, 21.22, 34.18 and16.69 mm, while the average lateral error of human operator was 32.70, 4.85, 7.85, 38.35 and 14.75 mm for straight path, curved path, sine wave path, offset discontinuity, and angle discontinuity respectively. The best execution time of image processing was obtained with the minimum values of the camera resolution at 500 mm camera height. While, increasing the size of nozzle at same height and spray pressure decreased the flight time. The favorable robotic platform' speeds were obtained at lower values of camera resolutions and wider distances between nozzle and camera.

Modified Perturb and Observe MPPT Algorithm for Drift Avoidance in Photovoltaic Systems

The perturb and observe (P&O) maximum power point tracking (MPPT) algorithm is a simple and efficient tracking technique. However, the P&O tracking method suffers from drift in case of an increase in insolation $(G) $ , and this drift effect is severe in case of a rapid increase in insolation. Drift occurs due to the incorrect decision taken by the conventional P&O algorithm at the first step change in duty cycle during increase in insolation. A modified P&O technique is proposed to avoid the drift problem by incorporating the information of change in current $(\Delta I) $ in the decision process in addition to change in power $(\Delta P)$ and change in voltage $(\Delta V) $ . The drift phenomena and its effects are clearly demonstrated in this paper for conventional P&O algorithm with both fixed and adaptive step size technique. A single-ended primary inductance converter is considered to validate the proposed drift-free P&O MPPT using direct duty ratio control technique. MATLAB/Simulink is used for simulation studies, and for experimental validation, a microcontroller is used as a digital platform to implement the proposed algorithm. The simulation and experimental results showed that the proposed algorithm accurately tracks the maximum power and avoids the drift in fast changing weather conditions.

A MODIFIED PERTURB AND OBSERVE ALGORITHM FOR MAXIMUM POWER POINT TRACKING OF PHOTOVOLTAIC SYSTEM USING BUCK-BOOST CONVERTER

Perturb and Observe (P&O) maximum power point tracking (MPPT) algorithm is widely applieddue to its simplicity, costless and easy implementation. However, P&O tracking algorithm suffersfrom drift or instabilities due to change of irradiance, and oscillation around maximum power point(MPP) at steady state. Drift occurs due to the incorrect decision taken by the conventional P&Oalgorithm at the first step change in duty cycle during the change in irradiance. This paper modifiesconventional P&O algorithm to overcome these drawbacks and improve MPPT performance ofphotovoltaic (PV) system and DC/DC converter to supply a resistive load under rapidly change ofweather conditions. This modified technique is proposed to avoid the problem of irradiancevariation by incorporating the information of voltage, current and power in the decision process forupdating the duty cycle of the converter. Simulation results of the proposed algorithm achievedminimum power oscillations with high accuracy, better dynamic response and stability for changesof irradiance, load and temperature. The obtained results are compared with the previousexperimental results which are obtained in the literature.

Speed control of synchronous machine by changing duty cycle of DC/DC buck converter

Renewable energies such as wind or solar energy are naturally intermittent and can create technical challenges to interconnected grid in particular with high integration amounts. In addition, if wind or solar is used to supply power to a stand-alone system, continuous power supply will be met only if sufficient energy storage system is available. The global penetration of renewable energy in power systems is increasing rapidly especially wind and solar photovoltaic (PV) systems. Hybrid wind and solar PV generation system becomes very attractive solution in particular for stand-alone applications. It can provide better reliability since the weakness of one system could be complemented by the strength of the other one. When wind energy is integrated into grid, maximum power point tracking control could be used to optimize the output of wind turbine. In variable speed wind turbine, the turbine speed is varied according to the wind speed. This paper presents a comparison between two methods of controlling the speed of a wind turbine in a microgrid namely; Proportional-Integral (PI) control of the tip speed ratio and stored power curve. The PI method provides more controllability, but it requires an anemometer to measure the wind speed. The stored power curve method, however, is easier to implement, but the amount of energy extracted can be less. The system has been modelled using Matlab/Simulink.

Fabrication of digital rainbow holograms and 3-D imaging using SEM based e-beam lithography.

Here we present an approach for creating full-color digital rainbow holograms based on mixing three basic colors. Much like in a color TV with three luminescent points per single screen pixel, each color pixel of initial image is presented by three (R, G, B) distinct diffractive gratings in a hologram structure. Change of either duty cycle or area of the gratings are used to provide proper R, G, B intensities. Special algorithms allow one to design rather complicated 3D images (that might even be replacing each other with hologram rotation). The software developed ("RainBow") provides stability of colorization of rotated image by means of equalizing of angular blur from gratings responsible for R, G, B basic colors. The approach based on R, G, B color synthesis allows one to fabricate gray-tone rainbow hologram containing white color what is hardly possible in traditional dot-matrix technology. Budgetary electron beam lithography based on SEM column was used to fabricate practical examples of digital rainbow hologram. The results of fabrication of large rainbow holograms from design to imprinting are presented. Advantages of the EBL in comparison to traditional optical (dot-matrix) technology is considered.

Implementation of a modified incremental conductance MPPT algorithm with direct control based on a fuzzy duty cycle change estimator using dSPACE

Maximum power point tracking (MPPT) is a necessary function in all photovoltaic (PV) systems. The classic incremental conductance (IC) MPPT algorithm is widely used in the literature. However, when large changes occur in the irradiance, the performance of this algorithm is degraded. To eliminate all of the disadvantages of the classic IC algorithm, we developed a new IC controller based on a fuzzy duty cycle change estimator with direct control. A fuzzy logic estimator (FLE) is used to estimate the new duty cycle used to track the PV array maximum power point. Compared with the fixed step IC MPPT method with direct control, the proposed algorithm reaches the MPP more accurately and faster during dynamic and steady-state conditions. A controlled Cuk DC–DC converter was implemented and connected to a SunTech STP085B PV panel to verify the accuracy of the proposed method. Matlab/Simulink was used for the simulation studies. Additionally, the algorithms were digitally implemented on the dSPACE ACE1104 platform. The results obtained confirm the advantages of the proposed algorithm.

Mapping ion stability in digitally driven ion traps and guides

Spreadsheet based programs for facile production of stability diagrams have been developed to accommodate the need for rapid generation for any change in the duty cycle of rectangular waveforms. In this publication, we have used these programs to demonstrate the effects of duty cycle manipulation and visually revealed the changes in the stability diagrams for each change. The concept of equating duty cycle change with a change in the Mathieu parameter a has been reexamined and found to be incorrect with respect to matrix methods definitions. The suggestion that the 50% duty cycle stability region can be mapped by varying the duty cycle to scan along lines of constant a/q is also shown to be incorrect. These observations were possible because the spreadsheet program allowed quick alteration of the waveforms and then observation of the stability results. Finally, the needs of the operator were examined. Because the stability diagrams have to be recalculated with each change in duty cycle, it is more helpful to use the matrix methods to directly calculate the stability diagrams at a=0 as a function of m/z and frequency. It is our intention to make these spreadsheet programs freely available to facilitate the mainstreaming of digital ion trap and guide technology.

Research on pulse electrodeposition of Fe-Ni alloy

Fe-Ni alloys were fabricated on steel substrates by means of pulse electrodeposition in sulfate solutions. The layers were electrodeposited using different peak current densities, duty cycles and frequencies. Fe contents, microhardnesses and crystalline phases were examined systematically. The Fe content in the deposit decreased and the microhardness increased with increasing duty cycle and peak current density. The pulse frequency had little effect on Fe content but led to a slight decrease in microhardness. X-ray diffraction patterns show that the crystalline phases vary with changes in peak current density and duty cycle but are barely influenced by frequency. When the peak current density or duty cycle is relatively low, crystalline Fe-Ni alloy and pure Fe phases coexist; the pure Fe phases disappear as the peak current density or duty cycle increases. At still larger peak current densities or duty cycles, crystalline Fe-Ni alloy and pure Ni phases coexist.

Achieving energy-synchronized communication in energy-harvesting wireless sensor networks

With advances in energy-harvesting techniques, it is now feasible to build sustainable sensor networks to support long-term applications. Unlike battery-powered sensor networks, the objective of sustainable sensor networks is to effectively utilize a continuous stream of ambient energy. Instead of pushing the limits of energy conservation, we aim to design energy-synchronized schemes that keep energy supplies and demands in balance. Specifically, this work presents Energy-Synchronized Communication (ESC) as a transparent middleware between the network layer and MAC layer that controls the amount and timing of RF activity at receiving nodes. In this work, we first derive a delay model for cross-traffic at individual nodes, which reveals an interesting stair effect . This effect allows us to design a localized energy synchronization control with ℴ( d 3 ) time complexity that shuffles or adjusts the working schedule of a node to optimize cross-traffic delays in the presence of changing duty cycle budgets, where d is the node degree in the network. Under different rates of energy fluctuations, shuffle-based and adjustment-based methods have different influences on logical connectivity and cross-traffic delay , due to the inconsistent views of working schedules among neighboring nodes before schedule updates. We study the trade-off between them and propose methods for updating working schedules efficiently. To evaluate our work, ESC is implemented on MicaZ nodes with two state-of-the-art routing protocols. Both testbed experiment and large-scale simulation results show significant performance improvements over randomized synchronization controls.

Efficiency analysis of a multi-fuzzy logic controller for the determination of operating points in a PV system

Photovoltaic power characteristics have multiple local and global maximum power operating points due to nonlinear solar insolation. To track the operating point exactly, suitable algorithm is needed. In this paper, a new multi-fuzzy logic based maximum power point tracking controller is proposed and the tracking performance is examined with one day solar insolation data. The proposed algorithm follows current control for better performance of the converter. The output of the proposed method, that is the reference current, controls the DC–DC boost converter as per the changes of photovoltaic power, voltage, and converter duty cycle. Implementation is done in MATLAB/Simulink and the PV power is evaluated and its characteristics are compared. The comparative analysis with fuzzy logic controller and P&O algorithm shows that, the proposed controller takes less time to settle at the maximum power operating point, eliminated oscillation around the operating point and also reduced the steady state error by 1.29% and 1.76% respectively.

Intelligent Production of Quality Apparels

Example applications are developed, covering typical sections of garments manufacturing and addressing robotic solutions in three different contexts. The first deals with the fabric storing and sorting sections. The case aims at the integrated management of cloth data (included each bolt failure maps), so that the work-plans setting progresses according to optimal schedules, without surprises of defective parts to be replaced. The change is made possible after re- design of fabric warehousing, with higher automation, in order that all pertinent data on cloth quality are monitored, shared, exploited and up-dated. The second one addresses the laying and cutting sections, already fully operated by unmanned mode. The upgrading looks at knowledge intensive setting, for on-process management of discontinuities, making easy the combined-mode (batch and one-of-a-kind) schedules to expand plant flexibility, joined to early removal of defective parts (using fabric fault maps). The development specifically requires re-thinking the enterprise policy, with minor changes of the computer interfaces, but proper resetting of the shop information system. The third context differs, as we refer to assembly and sewing sections, still, mainly operated by front-end workers. It should be said that the setting of fully automatic sewing cells has been conceived and actual fixtures exist for the mass production of steady specialised articles; yet, this is hardly consistent with economy of scope; a different implementation is outlined, with front-end workers and shared information steering duty-cycle changes. Again, proper improvements are obtained, with benefits requesting little investments in hardware, rather than work-plans up-dating depending on the process progression.

Parametric study of a Mach 1.3 cold jet excited by the flapping mode using plasma actuators

This paper describes an investigation into numerical and physical parameters influencing an ideally-expanded Mach 1.3 jet excited by the m=±1 flapping mode. The nozzle exit properties of the perfectly expanded jet include: ρjet=1.576kg/(m3), Tjet=224K, Re=1.1×106, and T0jet=Tambient=300K. The excitation is imposed by eight Localized Arc Filament Plasma Actuators (LAFPA) placed around the periphery of the circular nozzle exit. The reference controlled case considers the most amplified (jet column mode) frequency corresponding to a Strouhal number of 0.3 based on the diameter of the nozzle and jet velocity, with an actuator-imposed temperature of 1500K and a duty cycle of 20%. Relative to this reference, the effects of changing frequency, duty cycle and actuator model temperature are explored and results are compared with experimental data where available. The results are analyzed with several different quantitative and qualitative metrics, including time-averaged centerline decay and jet half-width as well as phase-averaged coherent structures. Raising the frequency affects the dynamics in several ways; the number of features observed in the phase-averaged data increases and the rate of decay of the centerline velocity is reduced. The alternating vortex ring interactions observed in the reference case are not distinct but are rather replaced by smaller structures, trends which are also observed in experiment. Lowering the Strouhal number increases mixing until a reversal occurs at St=0.1. The higher duty cycle exhibits strengthened coherent structures and slightly higher jet growth along the flapping plane, but the overall dynamics remain the same. The response of the jet is relatively insensitive to actuator temperature model within reasonable limits. The latter two studies, with different duty cycles and actuator temperatures, are consistent with previous analyses demonstrating that instability manipulation, rather than heat deposition is the primary mechanism of control.

Synthesis of functionally graded nano Al2O3–Ni composite coating by pulse electrodeposition

The main goal of this research is the synthesis of functionally graded nickel–nano Al2O3 composite coatings by using pulse deposition in which the amount of the embedded nano alumina particles changes in the cross section of the composite. For producing functionally graded nanocomposite coatings by pulse electrodeposition under ultrasonic agitation, frequency and duty cycle changes can be applied and in this research, the influence of both parameters has been studied. Microstructure of these coatings investigated by SEM, EBSD and XRD methods. By changing the duty cycle from 90% to 10% at different frequency, the microstructure of the coatings did not change significantly. These coatings showed ductile structure with {001} texture at primary layers and small randomly oriented grains at final layers. The most important factor affecting the microstructure of the nickel matrix was the average current density and incorporation of nano alumina particles does not have significant effect on the microstructure. The optimum condition for production of functionally graded nano Al2O3–Ni coating was changing of the duty cycle from 90% to 10% at fixed frequency of 10Hz.

Duty cycle-based isolation in linear quadrupole ion traps

Simulation and matrix methods were used to determine the change in the minimum trapping frequency during duty cycle base waveform manipulation to provide axial trapping. Duty cycle based axial trapping sets both rod sets of a digitally driven linear quadrupole to the same potential thereby nullifying the radial trapping field for a definable interval during the waveform cycle. Turning off the radial trapping field affects the ion motion. Consequently, the ion stability conditions and the secular frequency change with duty cycle during axial trapping. The work presented here demonstrates the change in the ion motion by simulating the ion trajectories under duty cycle base trapping conditions and determining the change in the minimum trapping frequency as a function of the change in duty cycle. The change in the stability conditions with duty cycle was determined by matrix methods. These calculations were used to determine the minimum trapping frequency change with duty cycle and validate the simulations. They were then used to discuss the duty cycle effects and propose methodology for using duty cycle waveform manipulation to perform precise ion isolation. Finally, matrix methods were used to show that ion isolation can be performed concurrently with duty cycle based axial trapping. These results were confirmed by simulation.

Novel Battery Charging Control System for Batteries Using On/Off and Pwm Controllers for Stand Alone Power Systems

Photovoltaic or in short term PV is one of the renewable energy resources that recently has become broader in nowadays technology. The demand or future work is looking for high efficiency, more reliable and economical price PV charge controller which is come in portable size has become very popular in PV system. In this paper, two different topologies of chargers will be simulated using proteus professional software. Both configurations are designed based on microcontroller (Atmega 32) which reduces complexity in the number of electronic components and increased monitoring and regulative functions. Pulse width modulation (PWM) will be implemented on a MCU to control duty cycle and voltage. Liquid Crystal Display (LCD) is used to display the voltage from rechargeable battery. The benefit of this project is an improvement of efficiency depend on duty cycle and voltage change.

Compromise revisited: inhibitory synapse and electrical coupling effects on bilateral phasing in the leech heartbeat system

The leech heartbeat central pattern generator (CPG) consists of a network of heart interneurons (HN) that coordinate heart excitor (HE) motor neuron activity via inhibitory chemical synapses. Each segmental pair of HE’s is connected to one another via electrical coupling. Depending on the segment, the pair of motor neurons in the living system is active across a wide range of phase differences from nearly in-phase to anti-phase [1]. Prior efforts to model this complete network have not quantitatively matched the intersegmental phase differences observed [2]. We have created a reduced network model in Simulink to explore parameters that contribute to these phase differences. In our network model, we implemented known neuronal properties and synaptic connections from a single segmental ganglion as shown in Figure ​Figure1.1. In our initial model run, the HN’s were modeled as endogenous bursters as previously described [3]; the HE’s were modeled as tonic firers. We varied three parameters in this study: phased delay of the right HN synaptic input (ΦSyn) and the maximum conductances of the inhibitory synapse (gSyn) and electrical coupling (gcoup). Figure 1 Leech heartbeat circuit diagram showing identified heart interneurons (HN) of the CPG and their pattern of inhibitory synaptic connections (lines with circles) onto each other and the heart excitor motor neurons (HE). The resistor symbol indicates rectifying ... We found that in this network gSyn must be at least 150 times greater than gcoup in order to obtain 1:1 entrainment of the HE’s with the HN’s. Under conditions with zero ΦSyn, increased gcoup led to increased instantaneous spike frequencies (ISF) and reduced duty cycle, primarily due to a delayed burst beginning. Increasing gSyn alone with zero ΦSyn led to little change in HE phase or duty cycle, but saw increased ISF. With relatively high levels of gSyn (300-600 nS), increasing ΦSyn (0.2-0.5) caused one HE to decrease its duty cycle while the other increased. Higher levels of ΦSyn (0.5-0.8) caused the HE’s to switch their relative duty cycle patterns. With weak gcoup (0.25-0.50 nS) and moderate ΦSyn (0.4-0.6), increasing gSyn led to a reduced HE duty cycle and side-to-side phase difference. The largest phase differences were found when both gSyn and gcoup were relatively strong. In summary, increases in gcoup tended to lead to increased phase differences, while increases in gSyn led to decreased phase differences. Our search of parameter space has provided a foundation for understanding the mechanisms underlying variable phase differences in neuronal networks and reinforced the importance of compromise between synaptic and neuronal properties for producing functional motor patterns.

Narrowband Notch Filters with Composite Nanostructure Layers on a GaN-Based Light Emitting Diode

In this paper, novel active narrowband notch filters with triple-layer composite nanostructures on a GaN-based LED are obtained by mainly adjusting the grating period and duty cycle. The three layers consist of two dielectric thin layers and one metallic / dielectric grating layer. The grating layer composes of subwavelength period and thickness rectangular stripes, which lies between a transition layer and a protecting layer. Line-width and attenuation peak properties of the resonance filters are calculated and investigated by using a full vector implementation of Rigorous Coupled Wave Analysis (RCWA) algorithm. It is shown that the grating period can significantly change the filter peak wavelength, and the grating duty cycle heavily changes the filter line-width. The filter attenuation peak has a red shift with 23.3nm as the grating period increases 18nm. The FWHM (Full Width at Half Maximum) of the filter reduces from 1.9nm to 0.28nm as the duty cycle changes from 0.55 to 0.3, which compressed more than six times. Moreover, thickness of each composite nanostructure layer can also affect the narrowband width and peak wavelength of the filter. The results provide guidance in designing, optimizing and fabricating such an active narrowband filter with highly integrated photonic devices.

Optimal choice and design of different topologies of DC–DC converter used in PV systems, at different climatic conditions in Egypt

This paper investigates the effect of changing cell temperature and solar irradiance on the choice and design of different topologies of DC–DC converter commonly used in photovoltaic (PV) systems. Under fluctuation of climatic conditions, the maximum power point (MPP) of PV generator will change. The maximum power point tracker (MPPT) must adjust the converter duty cycle to track the new MPP. Thus the converter must be chosen to be able to match the MPP under different atmospheric conditions. In addition, when the duty cycle changes as a result of changed climatic conditions, the boundary of the converter design parameters will change. So these parameters must be chosen to achieve the highest performance at all. The study shows that, only the buck–boost and the C′uk converter are capable of achieving the optimal operation regardless of the load value. And for a permanent operation in continuous conduction mode the filter inductance for all converter topologies must be greater than the maximum value of boundary inductance. Also in order to limit the ripple in the output voltage below a certain value, the filter capacitance must be larger than the maximum value of boundary capacitance.

Influence of duty cycle on the microstructure and microhardness of pulse electrodeposited Ni–CeO 2 nanocomposite coating

The Ni–CeO 2 nanocomposite coatings have been synthesized by pulse electrodeposition technique with different duty cycles (6, 9 and 17%) from a Watts-type electrolyte containing nano-sized CeO 2 particles. The XRD results show that the (2 0 0) orientation is dominant over (1 1 1) orientation in the Ni–CeO 2 nanocomposite coatings prepared with 6 and 17% duty cycles, while the opposite is true for the sample prepared with 9% duty cycle. The maximum amount of CeO 2 (10 wt%) incorporation in the coating occurs at 9% duty cycle. The crystallite size changes from micrometer to nanometer as the duty cycle changes from 6 to 9%. The hardness increases as the duty cycle increases from 6 to 17%. However, a coating with optimum smoothness and small number of microcracks is obtained at 9% duty cycle.