Long Duty Cycle Research Articles

Contribution to the Development of a Smart Ultrasound Scanner: Design and Analysis of the High-Voltage Power Supply of the Transmitter

A smart ultrasound scanner plays an important role in the transition to point-of-care imaging. DC–DC bipolar converters are essential in the generation of the ultrasound burst signal as they power the piezoelectric transducer. The conventional bipolar converter has minimal output gain and high-voltage stress, and the longer duty cycle on the semiconductors produces high conduction losses and reduces the efficiency of the system. The transmitter supply voltage is minimal, necessitating the use of high-gain bipolar converters. This proposed study is concerned with the development of an improved high-output voltage gain symmetric bipolar DC–DC converter topology which may be suitable for applications such as powering a smart ultrasound scanner transmitter. The proposed converter combines the conventional single-ended primary inductor converter (SEPIC) with a voltage multiplier cell (VMC) to improve voltage gain, transistor duty cycle, efficiency, and reliability. The present study describes the working principle of the proposed converter. The analysis of the voltage gain is carried out in continuous current mode (CCM) and discontinuous current mode (DCM), taking into account the nonidealities of the device. The simulation of the proposed system is carried out in the numerical environment Matlab/Simulink in order to verify its characteristics. A prototype model is realized and the experimental study presented validates the theoretical arguments and simulations. Due to the advantages of continuous input current, self-balancing bipolar outputs, and small component size, the proposed converter is a suitable choice for smart ultrasound transmitters.

A new phase-change cooling method for the frequent start-stop electric motor

Temperature control is critical to keep frequent start-stop electric motor running stably. A new phase-change cooling method is proposed for the frequent start-stop electric motor. The influence of the thermophysical properties of phase change material (PCM) and the operational mode of the electric motor on the proposed cooling method was analyzed to provide knowledge for the development of PCM and the operation optimization of electric motor. The numerical simulation results indicate the excellent performance of the proposed cooling method. The average temperatures of the stator core and the stator coil can be reduced by 7.5 K and 1.2 K for a single cycle when SP58 is chosen as PCM, while they can be decreased by 8.7 K and 2.4 K when the duty cycle is 0.67. The effect of the proposed method is more significant at the higher thermal conductivity and volumetric melting heat of PCM and the longer duty cycle.

Exploration of Sn70Li30 alloy as possible material for flowing liquid metal plasma facing components

• First wetting data for Sn 70 Li 30 alloy are reported on 316 SS, Mo and W substrates. • Wetting temperatures of 360 °C, 390 °C and 405 °C were measured respectively. • Alloy contamination/passivation worsened wettability with Δ T~130 °C in worst cases. • First depth profile characterization of the tin-lithium alloy by SIMS-ToF was carried out. • Mixing boundaries between alloy and substrates studied by SEM/EDS and 3D microscopy. • Lithium and tin induced corrosion found on 316 SS exposed at T < 550 °C during t ≤ 3 h. • Molybdenum and tungsten presented good compatibility after equivalent interaction. As an advanced alternative to solid materials, Liquid Metals (LM) may offer more resilient and feasible Plasma Facing Components (PFCs). Particularly, regarding the unavoidable material erosion/degradation produced by particle/heat fluxes in future fusion devices where much longer duty cycles are expected. Furthermore, configurations that propose a flowing LM surface can add the advantage of a continuously fresh and clean layer facing the plasma. Although lithium is the most widely tested option, tin-lithium (SnLi) alloys have been proposed to attempt to combine the positive characteristics of both pure elements and ameliorate the specific issues of lithium. In this work, the potential use of Sn 70 Li 30 alloy in such flowing concepts has been explored by addressing several preliminary and mandatory aspects for its utilization. Key issues such as wettability and compatibility of the alloy with relevant substrates have been studied in a multidisciplinary approach. The data obtained from deposited liquid tin-lithium droplets indicates approximate wetting temperatures of 360 °C, 390 °C and 405 °C for the fresh alloy on 316 stainless steel, molybdenum, and tungsten, respectively. However, the alloy contamination appeared to strongly affect the wetting characteristics of materials, increasing their wetting temperature by ~130 °C in the worst observed cases. Interestingly, in some instances, the instability of the liquid alloy surface was observed in the form of sudden gaseous ejection. The deposited droplets were posteriorly characterized in terms of absolute composition and depth profile by Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) and Secondary Ion Mass Spectrometry (SIMS-ToF). Additionally, the nature and composition of the boundaries between the substrates and alloy microparticles was investigated by Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), and 3D Laser microscopy. The overall results of this post-mortem characterization revealed that first signs of corrosion induced by both alloy elements (lithium-chromium association and iron-tin intermetallic mixing) were present on 316 stainless steel after short exposures (≤3 h) at temperatures lower than 550 °C. Conversely, molybdenum and tungsten showed good compatibility with the alloy in equivalent conditions. The global implications of these results are finally addressed, focusing on the future perspectives and the more viable scenarios for the eventual utilization of these alloys in flowing liquid metal configurations.

Full-Featured, Real-Time Database Searching Platform Enables Fast and Accurate Multiplexed Quantitative Proteomics.

Multiplexed quantitative analyses of complex proteomes enable deep biological insight. While a multitude of workflows have been developed for multiplexed analyses, the most quantitatively accurate method (SPS-MS3) suffers from long acquisition duty cycles. We built a new, real-time database search (RTS) platform, Orbiter, to combat the SPS-MS3 method's longer duty cycles. RTS with Orbiter eliminates SPS-MS3 scans if no peptide matches to a given spectrum. With Orbiter's online proteomic analytical pipeline, which includes RTS and false discovery rate analysis, it was possible to process a single spectrum database search in less than 10 ms. The result is a fast, functional means to identify peptide spectral matches using Comet, filter these matches, and more efficiently quantify proteins of interest. Importantly, the use of Comet for peptide spectral matching allowed for a fully featured search, including analysis of post-translational modifications, with well-known and extensively validated scoring. These data could then be used to trigger subsequent scans in an adaptive and flexible manner. In this work we tested the utility of this adaptive data acquisition platform to improve the efficiency and accuracy of multiplexed quantitative experiments. We found that RTS enabled a 2-fold increase in mass spectrometric data acquisition efficiency. Orbiter's RTS quantified more than 8000 proteins across 10 proteomes in half the time of an SPS-MS3 analysis (18 h for RTS, 36 h for SPS-MS3).

The suppression of flying-wing roll oscillations with open and closed-loop spanwise blowing

Uncommanded self-induced roll oscillations cause significant challenges in flight control and are ubiquitous in high-attack-angle flights in the flying-wing configuration. Spanwise blowing slots were designed in this article to suppress these roll oscillations with nonzero mean angles of a 53° swept flying-wing model. Three flow control strategies were proposed and studied successively. The open-loop symmetric blowing successfully suppressed oscillations below the nominal angle of attack of 24° before losing its effectiveness. Subsequently, adaptive continuous blowing using the proportion-integral-differential algorithm was performed with symmetric pre-blowing to eliminate the ineffective region with a small blowing coefficient. Using this strategy, roll oscillations under all tested nominal angles of attack were successfully addressed as the nonzero trim angles were eliminated and the oscillations were suppressed. However, the air consumption needed to maintain the model balance was too large, which necessitated the development of pulsed blowing. Static force measurements showed that the blowing-induced rolling moment had a linear relationship with the duty cycle of blowing. The results from the particle-image-velocimetry tests revealed that the mechanism of the linear relationship was the increased duration of coherent vortices over a period at longer duty cycles. Based on the static experimental results, the model was stabilized via proportion-integral-differential adaptive blowing, which utilized the duty cycle as the control variable. Compared to the second strategy, the last one reduced the required mean blowing momentum coefficient by two orders of magnitude while maintaining a great control effect.

Locomotor kinematics and EMG activity during quadrupedal versus bipedal gait in the Japanese macaque.

Several qualitative features distinguish bipedal from quadrupedal locomotion in mammals. In this study we show quantitative differences between quadrupedal and bipedal gait in the Japanese monkey in terms of gait patterns, trunk/hindlimb kinematics, and electromyographic (EMG) activity, obtained from 3 macaques during treadmill walking. We predicted that as a consequence of an almost upright body axis, bipedal gait would show properties consistent with temporal and spatial optimization countering higher trunk/hindlimb loads and a less stable center of mass (CoM). A comparatively larger step width, an ~9% longer duty cycle, and ~20% increased relative duration of the double-support phase were all in line with such a strategy. Bipedal joint kinematics showed the strongest differences in proximal, and least in distal, hindlimb joint excursions compared with quadrupedal gait. Hindlimb joint coordination (cyclograms) revealed more periods of single-joint rotations during bipedal gait and predominance of proximal joints during single support. The CoM described a symmetrical, quasi-sinusoidal left/right path during bipedal gait, with an alternating shift toward the weight-supporting limb during stance. Trunk/hindlimb EMG activity was nonuniformally increased during bipedal gait, most prominently in proximal antigravity muscles during stance (up to 10-fold). Non-antigravity hindlimb EMG showed altered temporal profiles during liftoff or touchdown. Muscle coactivation was more, but muscle synergies less, frequent during bipedal gait. Together, these results show that behavioral and EMG properties of bipedal vs. quadrupedal gait are quantitatively distinct and suggest that the neural control of bipedal primate locomotion underwent specific adaptations to generate these particular behavioral features to counteract increased load and instability. NEW & NOTEWORTHY Bipedal locomotion imposes particular biomechanical constraints on motor control. In a within-species comparative study, we investigated joint kinematics and electromyographic characteristics of bipedal vs. quadrupedal treadmill locomotion in Japanese macaques. Because these features represent (to a large extent) emergent properties of the underlying neural control, they provide a comparative, behavioral, and neurophysiological framework for understanding the neural system dedicated to bipedal locomotion in this nonhuman primate, which constitutes a critical animal model for human bipedalism.

Electrical stunning in pacu (Piaractus mesopotamicus) using direct current waveform

In Brazil, pre-slaughter immersion in ice is used in most fish slaughterhouses. We aimed to study the parameters for electrical stunning in pacu (Piaractus mesopotamicus) as a way to reduce animal suffering during slaughter and the stunning effects on meat pH and rigor mortis. We evaluated 70 fish, divided into two groups. In group G205, fish were stunned with 205 Volts (V), 50 Hz, duty cycle of 70% and 1.3 Amp (A) applied for 45 s; in group G400, fish were stunned with 400 V, 30 Hz, duty cycle of 30% and 0.9 A, for 30 s. Electrical stunning was applied using a backpack electrofisher (Smith Root LR-24) in a plastic box with 80 L of fresh water. We determined the unconsciousness time through behavioral evaluation. Immediately after checking the return of consciousness, all fish were placed in a plastic box with 35 L of fresh water and 200 mg L−1 of benzocaine before bleeding. After slaughter, the first 10 fish from each group were identified and placed in refrigerated plastic boxes with ice for measurements of pH in the epaxial muscle as well as the rigor mortis index (RMI) at 0, 3, 6, 24, 72, 120 and 168 h after bleeding. All fish were effectively stunned. When the current was applied, we observed that all fish lost behavioral responses and reflexes instantly: fish stopped swimming, lost equilibrium, did not respond to painful stimuli, ceased opercular movements and did not show vestibulo-ocular reflex. The unconsciousness time was significantly higher in the G205 treatment, equal to 61.7 ± 13.4 s (P < .01), in relation to G400 50.1 ± 9.6 s, possibly related to longer exposure to the electric current and the longer duty cycle. The pH values (median, min-max) immediately after slaughter were: 6.80 (6.70–6.90) for G205 and 6.75 (6.60–6.80) for G400 (P > .05). All fish reached maximum rigor mortis (RMI = 100%) within 6 h post mortem. There was no external damage, vertebral fracture, hemorrhages or blood spotting in the meat. Electrical stunning in pacu seems to be feasible through the G205 parameters, due to the unconsciousness period longer than 1 min, which may allow minimum time period to proceed bleeding without suffering. More research is needed to provide best strategies to the fish industry, so that fish regulations regarding humane slaughter may be implemented.

The Effects of Duty Cycle on the Step Potential Electrochemical Spectroscopy (SPECS) and Electrochemical Impedance Spectroscopy (EIS) Analysis of Manganese Oxides for Electrochemical Capacitors

Step potential electrochemical Spectroscopy (SPECS) and electrochemical impedance spectroscopy (EIS) have been developed for characterising the performance of electrochemical capacitors. However the effects of the different duty cycle on the behaviour and analysis of electrochemical methods still need to be investigated. In SPECS method a small potential step is applied with a sufficient rest time to allow equilibrium between each step throughout an applied potential window. This small scan rate enables an electrode to reach to its maximum charge storage capabilities. More importantly, it allows separation of the charge storage mechanisms such as electrical double layer charge storage and diffusional processes. EIS method also can provide the different information about the electrochemical cell such as double layer capacitance, series resistance, charge transfer resistance and mass transport using a small AC excitation signal. However, the AC excitation signal can be large in magnitude for the electrochemical capacitors due to the cyclability over a large potential window. In this work, the combined SPECS and EIS methods have been applied to electrolytic manganese dioxide (EMD) in 0.5 M Na2SO4 between 0.0 – 0.8 V (vs SCE) at different duty cycles to examine the changes in charge storage mechanisms. Hence, the different scan rates and equilibrium times have been applied for the same electrode ink and electrolyte. Firstly, the same duty cycle with the same effective scan rate has been examined with increasing the step size and equilibrium time which is constituted of the scan rate of 10 mV in 120 s, 25 mV in 300 s and 50 mV in 600 s. Then, the longer duty cycle with slower discharge rate such as 25 mV in 10 min has been applied to compare the results of different duty cycles. So, nine different experiments have been run using the different step size of 10 mV, 25 mV and 50 mV and different equilibrium times ranging of 120 s, 300 s and 600 s. The outcome of this work indicates the systematic effects of different scan rate on the charge storage mechanisms. Also, it can be seen that, the average capacitance of the electrochemical cell from cycling voltammetry (CV), increased with decreasing the scan rate of the duty cycle.

Advanced low-beta cavity development for proton and ion accelerators

Recent developments in designing and processing low-beta superconducting cavities at Argonne National Laboratory are very encouraging for future applications requiring compact proton and ion accelerators. One of the major benefits of these accelerating structures is achieving real-estate accelerating gradients greater than 3MV/m very efficiently either continuously or for long-duty cycle operation (>1%). The technology has been implemented in low-beta accelerator cryomodules for the Argonne ATLAS heavy-ion linac where the cryomodules are required to have real-estate gradients of more than 3MV/m. In offline testing low-beta cavities with even higher gradients have already been achieved. This paper will review this work where we have achieved surface fields greater than 166mT magnetic and 117MV/m electric in a 72MHz quarter-wave resonator optimized for β=0.077 ions.

Effects of varying duty cycle and pulse width on high-intensity focused ultrasound (HIFU)-induced transcranial thrombolysis.

The goal was to test the effects of various combinations of pulse widths (PW) and duty cycles (DC) on high-intensity focused ultrasound (HIFU)-induced sonothrombolysis efficacy using an in vitro flow model. An ExAblate™ 4000 HIFU headsystem (InSightec, Inc., Israel) was used. Artificial blood clots were placed into test tubes inside a human calvarium and exposed to pulsatile flow. Four different duty cycles were tested against four different pulse widths. For all study groups, an increase in thrombolysis efficacy could be seen in association with increasing DC and/or PW (p < 0.0001). Using transcranial HIFU, significant thrombolysis can be achieved within seconds and without the use of lytic drugs in vitro. Longer duty cycles in combination with longer pulse widths seem to have the highest potential to optimize clot lysis efficacy.

Low-Frequency Therapeutic Ultrasound with Varied Duty Cycle: Effects on the Ischemic Brain and the Inner Ear

Sonothrombolysis is a promising modality for acute stroke treatment. In vitro data suggest a duty cycle dependence of sonothrombolytic efficacy of low-frequency applications. The aim of our study was to examine its impact on safety issues in a rat model of middle cerebral artery occlusion. Rats were exposed to transcranial 60-kHz ultrasound with varied duty cycles. To determine effects on the inner ear, the acoustic threshold was determined in additional healthy animals (acoustic evoked potentials). A short duty cycle (20%) resulted in significant adverse effects (ischemic volume, hemorrhage, functional outcome), which was not observed in longer duty cycle (80%). Continuous-wave insonation produced high rates of mortality and subarachnoid hemorrhage. Hearing was impaired independent of duty cycle. In conclusion, cerebral side effects may be efficiently reduced by modulation of pulsed parameters, which is in line with data on an improved efficacy with longer duty cycle. However, side effects on the auditory system were found to be independent of parameter settings. (E-mail: max.nedelmann@neuro.med.uni-giessen.de)

Incidence of Cardiac Arrhythmias With Therapeutic Versus Diagnostic Ultrasound and Intravenous Microbubbles

The purpose of this study was to determine the type of arrhythmias induced with therapeutic versus diagnostic transthoracic low-frequency ultrasound (TLFUS) transducers in the presence of intravenous microbubbles. Intravenous perfluorocarbon-exposed sonicated dextrose albumin (PESDA) microbubbles were infused or given as a bolus injection while TLFUS was applied in the standard parasternal and apical views with either a 1-MHz therapeutic ultrasound transducer or high-mechanical-index diagnostic ultrasound (1.7 MHz). Significantly more ectopy was produced by the therapeutic transducer, especially at higher-intensity settings in the continuous wave mode after bolus injections of PESDA (P < .001 compared with lower intensities and lower continuous infusion rates). Six patients (15%) had either clinical supraventricular tachycardia or nonsustained ventricular tachycardia after intravenous PESDA with therapeutic TLFUS. In comparison, diagnostic high-mechanical-index ultrasound produced only isolated ventricular ectopy and no sustained ventricular arrhythmias. Intravenously injected microbubbles and low-frequency therapeutic transducers operating at longer duty cycles and wide beam widths have the capability of eliciting clinically important arrhythmias in patients at high risk for such events.

HEMOGLOBIN/MYOGLOBIN O2 DESATURATION DURING ALPINE SKIING STRATIFIED BY AGE.

1772 Muscle contraction patterns and extreme joint angles observed during alpine skiing may impede blood flow and subsequent oxygen delivery affecting hemoglobin/myoglobin deoxygenation(OD) in working muscles. Although biomechanical analysis of giant slalom (GS) and slalom (SL) have previously been investigated, the relationship between the GS and SL for ΔOD in junior alpine skiers, stratified by age, has not been reported. Thirty individuals ranging in age from 9 to 17 years (13.5±2.3) were grouped by class and age: Group I, (J1; 17 to 18 yrs) and (J2; 15 to 16 yrs); Group II, (J3; 13 to 14 yrs); Group III, (J4; 11 to 12 yrs) and (J5; 9 to 10 yrs). Duel wavelength spectrophotometry (NIRS), was used to measure ΔOD in the capillary bed of the vastus lateralis during GS and SL events. MaximalΔOD (CI) was determined in the laboratory during thigh cuff ischemia. ANOVA revealed 33.8% greater ΔOD during the GS for all groups( p<0.05). When stratified by age, significant differences were observed for relative ΔOD (% CI) between groups as indicated by: Group I, GS-70.7% vs SL-52.1%; Group II, GS-82.9% vs SL-66.1%; Group III, GS-79.3% vs SL-71.4%. The greater ΔOD during GS is consistent with the hypothesis that oxygen delivery and blood flow are compromised due to the deeper joint angles and longer duty cycles during this event.

Status report on CLUE

The CLUE experiment uses a new cosmic ray detector array planned to operate for the next decade. It utilises a MWPC chambers sensitive to UV, to image Cherenkov radiation produced in cosmic ray showers. This approach is unique in that the instrument is insensitive to skylight backgrounds, has a threshold similar to that of visible Cherenkov experiments but a longer duty cycle. These features make possible a class of interesting cosmic ray physics experiments.The CLUE experiment has started operation with two of the ten telescopes that are foreseen for its beginning. These telescopes are at present at Roque de Los Muchachos in the Canary Islands, in the same site as the HEGRA experiment. A description of the telescopes is given and some data on the tests performed are presented.

Development and reversal of fatigue in human tibialis anterior.

The lack of easily measurable, objective physiologic indices of muscle fatigue in humans has hampered the evaluation of interventions that putatively inhibit muscle fatigue. In 6 healthy subjects, isometric fatigue of right and left tibialis anterior (TA) was produced using 180 s of intermittent electrical stimulation to the motor point (40 Hz, 650-ms or 250-ms trains, 1 train/s). The time course, magnitude, and reproducibility of fatigue and recovery from fatigue was established, and the effect of duty cycle measured. During fatigue, force fell rapidly in all subjects over the first 70 s, then fell more slowly. Recovery was also biphasic--force increased rapidly over the initial 30 s then slowly--and was incomplete at 300 s. Comparing duty cycles of 0.65 versus 0.25, the longer duty cycle caused a greater fall in force (-65% versus -29%; P < 0.001) and lower recovery (P < 0.02). In all subjects, left leg muscles fatigued more than right. We conclude that this noninvasive fatigue and recovery protocol is highly reproducible and that it may prove useful for evaluating the effects of pharmacologic or restorative interventions on human muscle fatigue.

Mechanical transients of single toad stomach smooth muscle cells. Effects of lowering temperature and extracellular calcium.

Smooth muscle's slow, economical contractions may relate to the kinetics of the crossbridge cycle. We characterized the crossbridge cycle in smooth muscle by studying tension recovery in response to a small, rapid length change (i.e., tension transients) in single smooth muscle cells from the toad stomach (Bufo marinus). To confirm that these tension transients reflect crossbridge kinetics, we examined the effect of lowering cell temperature on the tension transient time course. Once this was confirmed, cells were exposed to low extracellular calcium [( Ca2+]o) to determine whether modulation of the cell's shortening velocity by changes in [Ca2+]o reflected the calcium sensitivity of one or more steps in the crossbridge cycle. Single smooth muscle cells were tied between an ultrasensitive force transducer and length displacement device after equilibration in temperature-controlled physiological saline having either a low (0.18 mM) or normal (1.8 mM) calcium concentration. At the peak of isometric force, after electrical stimulation, small, rapid (less than or equal to 1.8% cell length in 3.6 ms) step stretches and releases were imposed. At room temperature (20 degrees C) in normal [Ca2+]o, tension recovery after the length step was described by the sum of two exponentials with rates of 40-90 s-1 for the fast phase and 2-4 s-1 for the slow phase. In normal [Ca2+]o but at low temperature (10 degrees C), the fast tension recovery phase slowed (apparent Q10 = 1.9) for both stretches and releases whereas the slow tension recovery phase for a release was only moderately affected (apparent Q10 = 1.4) while unaffected for a stretch. Dynamic stiffness was determined throughout the time course of the tension transient to help correlate the tension transient phases with specific step(s) in the crossbridge cycle. The dissociation of tension and stiffness, during the fast tension recovery phase after a release, was interpreted as evidence that this recovery phase resulted from both the transition of crossbridges from a low- to high-force producing state as well as a transient detachment of crossbridges. From the temperature studies and dynamic stiffness measurements, the slow tension recovery phase most likely reflects the overall rate of crossbridge cycling. From the tension transient studies, it appears that crossbridges cycle slower and have a longer duty cycle in smooth muscle. In low [Ca2+]o at 20 degrees C, little effect was observed on the form or time course of the tension transients.(ABSTRACT TRUNCATED AT 400 WORDS)

Acoustic-reflex dynamics for pulsed signals.

Contralateral acoustic-reflex measurements were taken for 10 normal-hearing subjects using a pulsed broadband noise as the reflex-activating signal. Acoustic impedance was measured at selected times during the on (response maximum) and off (response minimum) portions of the pulsed activator over a 2-min interval as a function of activator period and duty cycle. Major findings were that response maxima increased as a function of time for longer duty cycles and that response minima increased as a function of time for all duty cycles. It is hypothesized that these findings are attributable to the recovery characteristics of the stapedius muscle. An explanation of portions of the results from previous temporary threshold shift experiments on the basis of acoustic-reflex dynamics is proposed.

Some Parameters Influencing the Pitch of Amplitude Modulated Signals

The rise-fall time, duty cycle, and carrier frequency of a pulsed tone were systematically varied. Listeners matched the pitch of this signal to that of a sinusoidal comparison tone. Low SPL was used throughout. Two pitches were identified, one corresponding to the repetition rate (periodicity pitch), and the other to the carrier frequency (carrier pitch). The periodicity pitch decreased in audibility with the increase of any of the experimental variables. These variables had the opposite effect on the perception of the carrier pitch, which in general was audible only at the longer duty cycles. Individual listeners varied considerably in their ability to match the pitch of the pulsed tones. Comparison of the results obtained with pulsed sinusoids to those of pulsed noise suggest that the perception of a periodicity pitch depends upon the band width and spectral location of the pulsed signal's frequency components as well as envelope wave form fluctuation.