Duty Cycle Factor Research Articles

Enhancing the Precision of Proportional Electromagnetic Actuators used in Automatic Processes Control

In this study, an electromagnetic actuator is presented, that features precise proportional action and wide displacement capabilities. This actuator operates in two distinct modes. In the proportional mode, the actuator positions its mobile equipment within a 0 to 14 mm range, governed by the balance between electromagnetic force and spring elastic force. By employing the pulse width modulation (PWM) principle, the electronic control section finely tunes the duty cycle factor and the coil current, thus achieving precise displacement control. The displacement control was further enhanced through the integration of a magnetic sensor that correlates movement with the Hall Voltage. This additional feature augments the actuator's precision by providing real-time feedback on the position of the mobile equipment, thereby refining the overall control mechanism. In the modulated mode, the actuator's oscillation frequency spans from 1Hz to 10 Hz, requiring control from the arbitrary signal generator. The PWM waveform controller DRV101 and the related electronic circuits are powered by two stabilized encapsulated continuous voltage sources that are compact enough to fit inside the actuator housing. The final power stage was represented by two power IGBT transistors that are powered by an external continuous voltage source. Experiments were also realized for heat management and to measure the plunger force at different distances between 0 and 14 mm. These analyses aim to optimize performance across both operational modes, advancing the efficiency and reliability of precision control systems in automated processes.

Proposed Z-Source Electrical Propulsion System of a Fuel Cell/Supercapacitor-Powered Ship

The use of green energy to power ships in the marine industry has attracted increasing attention in recent years. This paper presents an inland river cruise ship supplied by a fuel cell (FC) as the main power source and a supercapacitor (SC) as the auxiliary power source. Its propulsion inverter adopts the proposed high-boost Z-source inverter, and the proposed high-voltage-boost Z-source inverter (HVB-ZSI) principle is studied. The advantages of this proposed HVB-ZSI in two cases are verified through simulation. In case 1, it can be seen that the capacitance voltage is only 250 V, and the maximum inductance’s inrush current at the start is less than 200 A. But the capacitance voltage of HVB-ZSI reaches 383 V, and the inrush current is 300 A. While considering different constraints of the propulsion system, four operating modes for the set of the FC and SC are proposed. The small-signal model of the propulsion system is derived, and the control strategy is studied. By controlling the shoot-through duty cycle and modulation factor, the FC power, output power, and state of charge (SOC) of the SC can be controlled. Finally, to verify the performance of the proposed propulsion system, a hybrid power ship prototype equipped with a 7.5 kw propulsion motor is constructed. Four modes of the entire system are simulated by MATLAB/SIMULINK, and its performance is analyzed with experimental results. These results show that the new Z-source propulsion system has a promising application in new energy ships, as it has higher reliability and lower complexity and cost compared to conventional propulsion systems.

Experimental investigation of hole geometry during electric discharge drilling of aerospace material sheet

In this research paper experimental investigation of hole geometry during electric discharge drilling (EDD) is reported on Arial material Inconel-718. Electric discharge drilling is extensively used for aerospace equipment and component manufacturing. Proper geometry and close dimensional tolerance play a very important role during operations and functioning of aerospace parts. One of the important application of electric discharge drilling is in creating cooling hole in gas channels of gas turbine engines and similar other high temperature applications. In order to understand the parametric effect on hole geometry during electrical discharge drilling on Inconel-718, experiments are conducted according to the Box-behnken design of experiments. Four main electric discharge drilling parameters considered: Flushing pressure, Discharge current, Pulse on time and Duty cycle factor. Parametric effects and their interactive influence on hole geometry are studied by plotting contour plots. Favourable range of process parameter: Flushing pressure (kPa): 26 – 30, Discharge current (amp): 2–2.5, Pulse on time (µs): 6 – 6.5, Duty cycle factor (%): 50 – 55. After validating the established favourable range, improved hole geometry in term of better circular hole is observed in range of 0.989 to 0.992. Reported results can be useful to aerospace equipment manufacturers for getting improved geometry of drilled hole and also main recommendation is useful developing efficient automation of EDD process for quality production.

Flow Field and Heat Transfer of an Impinging Synthetic Jet in the Presence of Cross-Flow: Application of SAS and DES Approaches

Nowadays, synthetic jets have various applications such as cooling enhancement and active flow control. In the present paper, the capability of two turbulence modelling approaches in predicting thermal performance of an impinging synthetic jet is investigated. These two approaches are scale adaptive simulation (SAS) and detached eddy simulation (DES). Comparisons between numerical data and experimental studies reveal that the ability of DES in predicting the asymmetrical trend of heat transfer profiles is better than SAS in almost all the study cases. Although, near the stagnation zone, the performance of SAS is superior. Results show that the effects of parameters such as frequency, cross-flow velocity and suction duty cycle factor are well predicted by both approaches. An increase of cross-flow velocity from 1.81 m/s to 2.26 m/s results in an improvement of [Formula: see text] near the stagnation point by almost 16.3% and 9.2% using DES and SAS, respectively.

Biomimetic Chaotic Sensor for Moderate Static Magnetic Field.

The effects of a static magnetic field on systems with chaotic dynamical behavior have attracted little attention so far. Here, Chua’s electronic circuit with an inductor placed in a static uniform magnetic field operating in a chaotic double-scroll regime is studied experimentally. The effect of the magnetic field on the duty cycle factor and the spike count rate, with spikes defined by crossings between the scrolls of the double-scroll attractor, is described. A slow monotonic variation in the duty cycle factor and constant spike count rate is observed for magnetic field intensities up to the threshold, where both these metrics change severely; the dynamic trajectory remains on one scroll and spikes disappear. The dependence of the static magnetic field intensity on Chua’s circuit resistivity at the threshold is given. Two biomimetic magnetic chaotic sensors are proposed: one based on one Chua’s circuit and another that can have various transfer functions and is composed of several independent Chua’s circuits.

A Novel Energy-Safe Algorithm for Enhancing the Battery Life for IoT Sensors’ Applications

Energy safe is mandatory for all isolated IoT tools, such as in long way roads, mountains, or even in smart cities. If increasing the lifetime of these tools, the rentability of the global network loop becomes more efficient. Therefore, this paper presents a new approach for saving energy inside the source nodes by supervising the state of energy inside each source node and calculating the duty cycle factor. The relationship between these parameters is based on an optimization problem formulation. In this respect, the present paper is designed to propose a new approach that deals with increasing the lifetime of the wireless sensor network (WSN)-attached nodes, as fixed in the application. The newly devised design is based on implementing the IEEE 802.15.4 standard beacon-enabled mode, involving a cluster tree topology. Accordingly, every subgroup is allotted to apply a specifically different duty cycle, depending on the battery’s remaining energy level, which contributes to creating a wide range of functional modes. Hence, various thresholds are defined. Simulation results prove the efficiency of the proposed approach and show the energetic benefit. The proposed flowchart has minimized the consumed energy for the WSN, which improves the battery lifetime and enhances the IoT application’s robustness. Simulations and experiments have been carried out under different conditions and the results prove that the proposed method is a viable solution.

Improving Duty Cycle-based MAC Protocol in Wireless Networks using AI and Machine Learning

Duty cycle of a Medium Access Control (MAC) protocol is made up of sleep phase, wake-up phase and listen phase. MAC protocols usually proposes to optimize the duration of the wake-up and listen phases, in order to increase the duration of the sleep phase, thereby reducing the unwanted energy consumption of the wireless node. In this paper, we propose an Artificial Intelligence (AI) and machine learning (ML) based approach, which uses a hybrid combination of Time Division Multiple Access (TDMA), Bitmap Assisted MAC (BMA) and Sensor MAC (SMAC). The machine learning layer utilizes the duty cycle in the MAC layer, and generates multiple solutions for a given wireless communication. The AI layer then selects the best solution from the generated solutions by incorporating a duty cycle factor in the selection function, thereby optimizing the duty cycle of the protocol. The proposed system shows a 15% improvement in communication speed, and a 10% reduction in energy consumption across multiple communications. We plan to further extend this work for rural India, and apply it to real time agricultural applications.

Experimental investigation on the evolution of axi-symmetrical synthetic jet

The characteristics of a novel axi-symmetrical synthetic jet in quiescent environment is investigated with laser-induced fluorescence flow visualization technique. It is found that the trajectory of vortex ring is not only related to the dimensionless stroke length, but also the suction duty cycle factor. For the case of fixed dimensionless stroke length, the diameter of vortex ring tends to become smaller in the downstream direction with the increase of suction duty cycle factor.

Numerical study of circular synthetic jets at low Reynolds numbers

In this paper, the flow patterns of circular synthetic jets issuing into a quiescent flow at low Reynolds numbers are studied numerically. The results confirm the presence of the three jet flow regimes, i.e. no jet formation, jet flow without rollup and jet flow with rollup reported in the literature. The boundaries of the different jet flow regimes are determined by tracking the structures produced by the synthetic jets in the near field of the jet orifice over several actuation cycles and examining the cycle-averaged streamwise velocity profiles along the jet central axis. When the Stokes number is above a certain threshold value appropriate for the corresponding flow regime, a good correlation between the flow patterns and the jet Reynolds number defined using the jet orifice diameter, ReDo, is also found. Furthermore, the flow structures of synthetic jets with different suction duty cycle factors are compared. The use of a high suction duty cycle factor strengthens the synthetic jet resulting in a greater penetration depth into the surrounding fluid. Overall, the finding from this study enables the flow regimes, in which a synthetic jet actuator with a circular orifice operates, to be determined. It also provides a way of designing more effective synthetic jet actuators for enhancing mass and momentum transfer at very low Reynolds numbers.

Frequency and duty cycle modulation optimization in minimizing thermal accumulation effect in Z-scan measurement with high-repetition-rate laser

In this study, we demonstrate the optimization of the chopper frequency and duty cycle in a Z-scan measurement with a 250 MHz high-repetition-rate (HRR) femtosecond laser to minimize the thermal lensing effect due to cumulative heating of the sample. The result shows that such minimization can be achieved by keeping the modulated exposure time on the sample shorter than the thermal diffusivity decay time tc. The minimum chopper frequency fmin is predicted by relating the duty cycle factor F with tc, while maintaining stable peak and valley transmittances, i.e., ΔTp and ΔTv, respectively. Furthermore, a lower fmin is obtained by taking a stable range of the peak–valley difference ΔTpv into consideration. The optimization allows for the low operational modulation frequency of Z-scan measurement with reduced thermal influence, thus enabling simple management of the thermal lensing effect.

The virtual aeroshaping enhancement by synthetic jets with variable suction and blowing cycles

A novel waveform modified from the standard-sinusoidal function is adopted to enhance the virtual aeroshaping effect of the synthetic jets positioned at the front stagnation point of a circular cylinder. The waveform is characterized by a control parameter, namely, the suction duty cycle factor k, which is the ratio of the time duration of the suction cycle to that of the blowing cycle. The strength of the synthetic jet vortex pair is enhanced by increasing the suction duty cycle factor. The periodic closed envelope forms upstream of the circular cylinder for k ≤ 1.00, while the quasi-steady open envelope forms for k ≥ 2.00, acting the virtual aeroshaping effect. As a result, both the statistical characteristics and the vortex dynamics of the near-wake flow field change with the suction duty cycle factor. The recirculation region downstream of the circular cylinder becomes smaller or even disappears, and thus, the drag coefficient over the circular cylinder is reduced by increasing the suction duty cycle factor to k ≥ 1.00. The statistical mean and fluctuating velocities show corresponding changes in the near wake with the different wake patterns. For k ≤ 0.50, the wake vortex shows the antisymmetric shedding mode which is similar with the natural case. For 1.00 ≤ k ≤ 2.00, the wake vortex shows the bistable state mode, where vortex sheds with symmetric or antisymmetric mode; the antisymmetric shedding mode dominates the global flow field for k = 1.00, while it is the symmetric shedding mode that dominates the flow field for k = 2.00. For k = 4.00, it shows the antisymmetric shedding mode with a shorter vortex formation length than the natural case. The above findings indicate that the virtual aeroshaping effect of the synthetic jets can be enhanced by increasing the suction duty cycle factor so as to increase the momentum coefficient while keeping other control parameters unchanged, providing us another way for effective flow control.

Electrosurgical generators

Electrosurgical generators

Synthetic jet control of separation in the flow over a circular cylinder

A synthetic jet generated by a non-sinusoidal waveform is used to control flow separation around a circular cylinder at Reynolds number 950. The synthetic jet is positioned at the rear stagnation point. The suction duty cycle factor defined as the ratio of the time duration of the suction cycle to the blowing cycle is introduced as the determining parameter. Increasing the suction duty cycle factor, the exit velocity and entrainment effect of the synthetic jet are enhanced, flow separation is delayed, and drag reduction by up to 29 % is achieved. Different mechanisms for separation control during both the blowing cycle and the suction cycle have been revealed. It is suggested that a better control effect can be obtained during the blowing cycle.

Multi-Objective Process Optimization of Pulsed Plasma Arc Welding SS400 Steel Pipe with Foamed Aluminum Liner

Principal component analysis (PCA) coupled with Taguchi methods are employed in the study for developing multiple quality characteristics optimization of pulsed plasma arc welding SS400 steel pipe with foamed aluminum liner (SPFAL). The quality characteristics investigated are the micro-hardness, the compression strength, and the bending strength of the weldments. Eight control factors selected are the tip aperture (Factor A), plasma base current (Factor B), plasma pulse current (Factor C), duty cycle (Factor D), pulse frequency (Factor E), shielding gas (Factor F), plasma gas (Factor G), and welding velocity (Factor H), respectively. It is shown by the experimental results that the optimal parameter combination of the pulsed plasma arc welding process is A1 (tip aperture: O1.5mm), B3 (plasma base current: 30A), C3 (plasma pulse current: 100A), D2 (duty cycle: 50%), E3 (pulse frequency: 300Hz), F2 (shielding gas: 14L/min), G3 (plasma gas: 0.4L/min), and H2 (welding velocity: 4RPM). Moreover, it is ascertained from the analysis of variance (ANOVA) results that plasma base current (B), plasma pulse current (C), duty cycle (D), and welding velocity (H) are the most important control factors in the process design, and thus strict control must be applied to them. They account for 75.02% of the total variance. The experimental results likewise show that the best process design could indeed enhance the multiple quality characteristics of the pulsed plasma arc welded SPFAL as 3020kgf of the bending strength, 13650kgf of the compression strength, and 180.4Hv of the hardness, respectively.

Effect of novel synthetic jet on wake vortex shedding modes of a circular cylinder

A novel actuator signal achieved by changing the ratio of the suction duty cycle to the blowing duty cycle is adopted to enhance the control effect of the synthetic jet for the flow around a circular cylinder. The suction duty cycle factor k defined as the ratio between the time duration of the suction cycle and the blowing cycle and the equivalent momentum coefficient C μ are introduced as the determining parameters. The synthetic jet is positioned at the rear stagnation point in order to introduce symmetric perturbations upon the flow field. The proper orthogonal decomposition (POD) technique is applied for the analysis of the spanwise vorticity field. Increasing the suction duty cycle factor, the momentum coefficient is enhanced, and thus a stronger and larger scale synthetic jet vortex pair with a higher convection velocity is generated. The synthetic jet vortex pair interacts with the spanwise vorticity shear layers behind both sides of the cylinder, resulting in the variations of the wake vortex shedding modes at Re=950: for k=0.25, C μ =0.148, vortex synchronization at the subharmonic excitation frequency with antisymmetric shedding mode; for 0.50≤ k≤1.00, 0.213≤ C μ ≤0.378, vortex synchronization at the excitation frequency with the symmetric or antisymmetric shedding modes; for 2.00≤ k≤4.00, 0.850≤ C μ ≤2.362, vortex synchronization at the excitation frequency with symmetric shedding mode. Hence, the control effect of the synthetic jet upon the wake vortex of a circular cylinder can be enhanced by increasing the suction duty cycle factor so as to increase the momentum coefficient. This is also validated at a higher Reynolds number Re=1600.

Experimental investigation of a novel two-dimensional synthetic jet

The novel signal wave pattern realized by changing the suction duty cycle factor K for a two-dimensional synthetic jet was investigated experimentally with a two-dimensional particle image velocimeter (PIV) system in quiescent flow. The development and evolution of the vortex pair trajectories, jet velocity, jet width, flow flux and momentum flux were obtained for different K values. It is found that the distributions of the mean and turbulent flow fields for synthetic jets generated at different K values have similar features to those exhibited for the conventional synthetic jet. Moreover, the vortex pairs generated in the present way have larger convection velocity, stronger entrainment and higher momentum at larger K , which would be of benefit for flow control applications.

Performance Limits of Optical Clock Recovery Systems Based on Two-Photon Absorption Detection Scheme

In this paper, we analyze and discuss the performance limits of optical clock recovery systems using a phase-locked loop (PLL) structure with nonlinear two-photon absorption (TPA) phase detection scheme. The motivation in analyzing the aforementioned optical PLL with TPA receiver structure is due to a recent successful experiment reported in . We characterize the mathematical structure of PLLs with TPA, so as to evaluate the performance limits on optical clock recovery mechanism. More specifically, we identify two intrinsic sources of phase noise in the system namely, the on- off nature of the incoming data pulses and the detector's shot noise that ultimately limit the performance of the aforementioned optical clock recovery system. In our characterization of the clock recovery system, we obtain the power spectral densities (PSDs) of the signals involved in the PLL and use the PSDs to obtain a mathematical expression for the variance of the timing jitter inherently associated with the recovered clock. We examine the variance of the introduced timing jitter as a function of different system parameters such as power, bit rate, and pulsewidth of the data and clock signals. An interesting result is that the duty cycle factor near 4 in return to zero optical pulses is optimal in the sense that it minimizes the variance of the system phase noise.

Novel Signal Wave Pattern for Efficient Synthetic Jet Generation

A novel signal wave pattern is proposed to generate a more efficient synthetic jet, and the unsteady and mean flow characteristics of the synthetic jet generated by different suction duty cycle factors k are examined by numerical simulation. The mean flowfields of the synthetic jet with different k have similar features to that exhibited in previous experiments, but they would have a stronger and larger scale vortex pair with a larger suction duty cycle factor k, when the two key parameters, the stroke length ratio L 0 /D and the Reynolds number Re U0 (based on the characteristic blowing velocity U 0 and the orifice scale D), are set to be constant. The suction duty cycle factor k affects the vortex strength formed during the blowing cycle only, and nearly does not influence the convection velocity and trajectory of the vortex. During the suction cycle, the entrainment effect of the actuator decreases with the increase of suction duty cycle factor k, so that the vortex pair can propagate farther and coalesce to synthesize a larger scale jet.

Effects of pulsating magnetic fields on electrolytic mass transfer around cylindrical cathodes.

The influence of pulsating magnetic fields on mass transfer was studied experimentally in the electroreduction of ferrocyanide ions around an inclined cylindrical cathode under diffusion-controlled conditions. The mass transfer rate is increased by applying the pulsating magnetic field as well as the static one. The time-averaged enhancement of the mass transfer rate is dependent markedly on duty cycle (ON-time ratio), peak magnetic flux density of the applied pulsating magnetic fields in a range of 20 to 200 mHz, and slightly on its frequency. The mass transfer coefficient was correlated well by two types of non-dimensional regression equations with and without a duty-cycle factor, by using the “magneto-diffusion factor” to express the contribution of the applied magnetic flux density.

Identification of lunar rock types and search for polar ice by gamma ray spectroscopy

The ability to map the surface composition of the Moon from orbit by means of gamma ray spectroscopy has been studied with attention to the possible use of small spinstabilized spacecraft. Two types of detectors were considered, a sodium iodide scintillator and a cooled germanium solid‐state device. The latter has superior sensitivity for all determinable elements, the difference ranging from factors of 3 to 11. A design for accommodating the preferred germanium detector gamma ray spectrometer (GeGRS) on either a small or large spacecraft has been devised. Detection sensitivity has been applied to typical rock compositions to determine measurement times and the ability to discriminate among representative lunar rock types. For sets comprising nine highland and 16 mare types, the most useful elements are found to be Mg, Al, K, Ti, Fe, U, and Th. Compositional distinctions combined with the sensitivity of the GeGRS instrument should allow each major rock type to be recognized in accumulation periods of 2 hours or less. The presence of two or more rock types in comparable abundance will require longer periods. Permanently shadowed polar areas of the Moon may be repositories of water ice. The expected instrument response to the resulting gamma ray and neutron fluxes has been analyzed. A neutron mode added to the spectrometer will be more sensitive to the possible presence of ice than the gamma ray mode, although without the application of compositional corrections based on analysis of the gamma ray data, most of the neutron mode sensitivity will be lost. With a pair of selected neutron absorbers, and a model which provides that 2.5% of the area above 75° latitude is occupied by trapping sites, the most sensitive of the configurations examined will provide a one year mission detection limit of 0.056% H2O by weight for each polar region. Given the postulated abundance of trapping sites, a determination of whether water is present in adequate abundance for resource utilization can be made within a week. These results are applicable to alternative spacecraft by simply adjusting the duty cycle factor.