Effect Of Different Waveforms Research Articles

Effects of pulse current waveform on electromagnetic railgun considering the eddy current effects

This paper investigates the effects of pulse current waveform on electromagnetic railgun considering the containment eddy current effects. First, a three-dimensional transient finite element model of the railgun with a metal containment and a pulse current waveform control model with constant feed energy are established. Then, taking the eddy current effect into account, the effects of different waveforms with constant feed energy on the eddy current, the rail current, the armature propulsive force, the rail repulsive force, the eddy current energy consumption, and the muzzle kinetic energy are analyzed. Finally, the simulation shows that reducing the slope of the rising edge of the pulse current can effectively suppress the eddy current and improve the muzzle kinetic energy. When the amplitude and the slope of the rising edge are determined, the excessively long flat top section will lead to more serious eddy current concentration at the ending moment of discharge, more eddy current loss, and less muzzle kinetic energy. Too high or too low amplitude of the pulse current is not conducive to the improvement of the muzzle kinetic energy. The investigation of this paper provides some references for the design of electromagnetic railgun and the selection of pulse current waveform.

The evoked compound nerve action potential is shaped by the electrical pulse-width

Abstract Introduction: Despite its central role in medicine electrical stimulation (ES) is still limited by its selectivity. Different reports did assess effects of different waveforms, intensities, and frequency on the activation threshold of nerve fibres with different diameters. We aimed to extend this knowledge by investigating the effect of short monophasic rectangular pulses (1, 2, 5, 10, 50, 100 and 200 μs) on the recruitment order. Methods:The sciatic nerve of rats was stimulated, and the evoked compound nerve action potential (CNAP) measured at two sites on the tibialis nerve, using epineural electrodes. Changes in delay, amplitude, and the shape of the CNAP were analyzed. Results:The amplitude and delay of the CNAP were significantly affected by the pulse-width (PW). The delay and duration of the compound nerve action potential increased with longer PW, while the amplitude decreased. Discussion:Found changes are likely caused by changes in the time point of excitation of individual neuron fibres, depending on electrical field strength and exposure time. This might be of particular interest when selecting PWs for design and validation of stimulation patterns and analysis of experimental and clinical observations.

Effects of paired stimulation with specific waveforms on cortical and spinal plasticity in subjects with a chronic spinal cord injury

Paired stimulation can cause neuroplasticity in corticospinal and spinal pathways in subjects with a chronic spinal cord injury (SCI). We aimed to know the effects of different waveforms using paired stimulations with bicycling in subjects with a chronic SCI. Recruited subjects with an SCI underwent three treatment interventions in random order for 4-20 min followed by 30 min of bicycling (control, repetitive transcranial magnetic stimulation (TMS; rTMS) at 20 Hz with transspinal direct current stimulation (tsDCS), and intermittent theta burst stimulation (iTBS) with tsDCS with a 1-week gap period. A TMS method was employed to record the resting motor threshold (RMT), the 90% values of which was used as the stimulation intensity, and the Hoffman (H)-reflex was measured by stimulating the tibial nerve in the popliteal fossa. The RMT, motor evoked potential (MEP) latency, MEP peak-to-peak amplitude, and H-reflex latency as primary variables and lower extremity motor scale (LEMS) and modified Ashworth spasticity scale (MAS) as secondary variables were analyzed before and after the interventions. The MEP latency, MEP amplitude, and LEMS significantly improved with the rTMS-iTBS/tsDCS or the rTMS-20 Hz/tsDCS (p < 0.050) protocols compared to the control intervention. All other outcome measures, including RMT, H-reflex latency, and MAS score showed some changes but did not fully attain a level of significance. The paired stimulation with rTMS-iTBS/tsDCS was equally effective to produce neuroplastic effect in subjects with chronic SCI compared to the conventional TMS-20 Hz/tsDCS intervention.

Effects of Electroacupuncture with Different Waveforms on Chronic Prostatitis/Chronic Pelvic Pain Syndromes: A Randomized Controlled Trial.

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is a common disorder in adult men. Evidence has demonstrated that acupuncture is effective for treating CP/CPPS. Electroacupuncture (EA) is a combination of traditional acupuncture and electrical stimulation, and the waveform is one of the key factors influencing EA effects. Different waveforms contain different stimulating parameters, thus generating different effects. However, the effects of different waveforms of EA on CP/CPPS remain unclear and there is no recommended standard for the application of EA waveforms. At the same time, the waveform prescription of CP/CPPS is also different, so exploring the influence of different waveforms on CP/CPPS patients will also provide a certain treatment basis for clinical treatment. A total of 108 eligible patients were recruited from the Seventh People's Hospital affiliated to the Shanghai University of Traditional Chinese Medicine from March 18, 2021, to January 31, 2022, according to inclusion and exclusion criteria. All subjects were randomly divided into three groups (continuous wave 4 Hz, continuous wave 20 Hz, and extended wave 4/20 Hz) in a ratio of 1 : 1 : 1. Patients in all three groups were treated for the same duration of 20 minutes, with intervention twice a week for 4 weeks. The changes in chronic prostatitis index (NIH-CPSI), erectile function index 5 (IIEF-5), Hospital Anxiety and Depression Scale (HADS), and NIH-CPSI response rate in three groups were compared after the intervention, and the occurrence of adverse events in patients during treatment was observed. After 4 weeks of treatment, the CP/CPPS response rates were 66.7%, 62.5%, and 88.2% in the 4 Hz, 20 Hz, and 4/20 Hz groups, respectively. The reaction rate of CP / CPPS in 4 / 20 Hz group was higher than that in 4 Hz group and 20 Hz group. (P < 0.05). During treatment, the difference between NIH-CPSI scores between 4 Hz and 4/20 Hz was insignificant (P > 0.05). NIH-CPSI scores were lower in the 4/20 Hz group than in the 4 Hz and 20 Hz groups (P < 0.05). After treatment, there was no significant difference in the pain and discomfort subscales (P > 0.05) between the 4 Hz and 20 Hz groups and there were significantly lower pain and discomfort scores in the 4/20 Hz group (P < 0.05) compared to the 4 Hz and 20 Hz groups. There was no significant difference in the reduction of urination symptoms and quality of life among the three groups (P > 0.05). Compared with before treatment, IIEF-5 scores of the three groups were improved (P < 0.05). After treatment, there was no significant difference between the IIEF-5 scores in 4 Hz and 20 Hz (P > 0.05), while the IIEF-5 score in 4/20 Hz was significantly higher than that in 4 Hz and 20 Hz, and the change was significant (P < 0.05). The HADS scores decreased in all the three groups (P < 0.05), but there was no significant difference in HADS scores between the three groups (P > 0.05). Adverse events were mild and transient, and no serious adverse events occurred in each group. Both the expansive and continuous waveforms of EA can effectively alleviate symptoms such as prostatitis, erectile dysfunction, anxiety, and depression in patients with CP/CPPS. Expansion waves are superior to continuous waves in improving erectile function and pain symptoms in chronic prostatitis and can be used as a preferred waveform for the treatment of CP/CPPS. Trial Registration. This trial is registered with Chinese Clinical Trial Registry, ChiCTR2100044418.

Experimental investigation of the effect of different waveforms on heat transfer in a thermoacoustic cooler

Thermoacoustic cooling systems are insufficiently compared to compressor compression cooling systems. The reasons for this should be investigated and solved. The performance of a thermoacoustic cooling system depends on many factors. The cooling system's success is possible by precisely determining the contributions of these factors to thermoacoustic cooling. However, both numerical and experimental studies in the literature on the subject contain certain limitations. One of the most important of these is that the studies were carried out with constant frequency and only a sine wave. This study examined the effect of this approach on thermoacoustic cooling. Thus, a polypropylene stack is placed in the resonance tube, and experiments were carried out. Air is used as a refrigerant. Five different wave types (sine, square, triangle, sawtooth, and trapeze) were used as wave types; resonance tube diameters were also selected as 50, 70, and 100 mm. The study determined that the resonance tube's diameter to be selected and the wave type were related. For the highest ΔT value, it turned out that the use of a 50 mm tube diameter sine wave, 70 mm tube diameter sawtooth wave, and 100 mm tube diameter trapezoidal wave were more appropriate than the other waveforms. the use of a sawtooth wave instead of a sine wave for the 70 mm tube diameter increased the cooling capacity by 2.61%, and trapezoidal wave usage for 100 mm tube diameter increased by 5.91%.

Configurable High-Frequency Alternating Magnetic Field Generator for Nanomedical Magnetic Hyperthermia Applications

This article shows the use of a high-frequency Full-Bridge inverter to design an alternating magnetic field generator for experimental studies on anti-cancer treatment with magnetic nanoparticles. In magnetic hyperthermia, nanoparticles are used to raise the pathological cancerous cell's temperature high enough to induce their death by apoptosis, but not as high as to destroy them by thermal ablation of the whole tissue volume, consequently leaving healthy cells alive. Conventionally, sinusoidal alternating magnetic fields are used to heat the nanoparticles, which can be more easily produced than other waveforms. However, there are no theoretical nor experimental reasons to choose the sinusoidal waveform. This work aims to develop an improved power system to study the effect of different waveforms of the magnetic field on heat production when exciting magnetic nanoparticles, aiming at demonstrating that other waveforms can be much more efficient in producing heat than conventional sinusoids. To prove our hypothesis, we designed an inverter able to generate four waveforms at high frequencies and a fifth sinusoidal signal derived by a resonant capacitor, in the range of 100 kHz to 1 MHz and up to 10 mT of peak intensity. Also, we used SiC devices to process high currents at high switching frequencies efficiently. Additionally, to enhance the system efficiency, Zero-Voltage Switching is used to reduce switching losses and minimize electromagnetic noise and interference. The experimental results obtained with non-sinusoidal waveforms have shown a remarkable performance improvement compared to classical sine wave excitation. The nanoparticles' heat dissipation depends on the applied alternating magnetic field's signal slope, signal frequency, and peak field intensity. We conclude that further work deserves to be done to find the optimum work conditions in function of the used particle and biological environment to test if this type of magnetic field generator could overcome the conventional system's performance.

Real-World Analysis: Long-Term Effect of Spinal Cord Stimulation With Different Waveforms for Patients With Failed Back Surgery Syndrome.

Spinal cord stimulation (SCS) is effective for patients with failed back surgery syndrome (FBSS). SCS improves their pain, as well as their functionality and health-related quality of life. Different waveforms for SCS have emerged that show improvement in small prospective studies. Analysis of real-world data shows the clinical implementation and the effect of different waveforms in SCS. A real-world analysis was performed of 208 patients with FBSS who were treated over 3 years. Stimulators with tonic, burst, high-density, and 10-kHz high-frequency (HF10) waveforms were implanted in patients with FBSS who had predominant pain in the back, legs, or both back and legs. Pain as measured by the VAS, functional disability as measured by the Oswestry Disability Index (ODI), and health-related quality of life as measured by the 3-level EuroQol 5-Dimension (EQ5D-3L) questionnaire were determined at baseline and for outcome assessment. SCS is effective for patients with FBSS. This analysis showed a change in baseline VAS score from 8.0 to 4.7 (P<0.0001) at 24months. The EQ5D-3L score improved from 0.29 to 0.49 (P<0.0001) at 24months. The ODI score improved from 54% to 42% (P<0.0001) at 24months. The unanticipated explantation rate was only 1.6%. This study of SCS showed significant long-term improvement in pain, disability, and quality of life in a large dataset of patients with FBSS. Strict selection procedures and a strong opioid policy contributed to the high success rate and low unanticipated explantation rate. There was no difference in pain reduction between tonic and HF10 stimulation. Further investigation is necessary to detect any difference between other waveforms of SCS.

Effect of different waveforms and harmonic frequency orders on bubble cavitation in dual-frequency ultrasonic intensification

A numerical investigation of ultrasonic dual-frequency waveform assisted transesterification was performed. The dual-frequency waveforms of square waves (SQ + SQ), sine waves (SIN + SIN), and sawtooth waves (ST + ST) were explored. For non-sinusoidal signals, the Fourier coefficient and Fourier series were applied to convert the signal into the sum of sinusoidal waves in order to determine the bubble cavitation using Rayleigh-Plesset equation. The bubble radius ratios (R/Ro) of each waveform were evaluated to find the maximum value. At fundamental frequencies, the maximum R/Ro were 37.08, 31.65, and 12.06 for SQ + SQ, SIN + SIN and ST + ST, respectively. This revealed that the SQ + SQ had a stronger effect on the bubble size than the others. In summary, SQ + SQ had strongest influence on cavitation. Then, harmonic frequency orders (HFOs) were investigated for these two non-sinusoidal waveforms. For SQ + SQ, R/Ro increased with increasing HFO. The maximum R/Ro of 41.29 occurred at the 9th HFO and then started to decrease after this order. On the other hand, for ST + ST, increasing the HFO had no positive effect on the R/Ro. Additionally, increase in HFO would only promote R/Ro if combined waves amplitude were increased. Finally, the optimised HFO will be further used for the enhancement of biodiesel yield.

Surgical Technique and Patient Selection for Spinal Cord Stimulation for Chronic Pain.

Spinal cord stimulation (SCS) is a neuromodulation surgical technique that allows the treatment of various causes of chronic pain. SCS is effective in the treatment of chronic low back pain, neuropathic pain, chronic regional pain syndrome, and failed back surgery syndrome, among others. The mechanisms underlying the efficacy are still under investigation and different mechanisms are likely responsible for the effects of different waveforms used in the therapy. Successful application of SCS to individual patients depends on patient selection and meticulous surgical technique. Important factors in patient selection depend on preoperative imaging, maximizing noninvasive therapy, and neuropsychological evaluation. Percutaneous and open techniques exist for placing both paddle-shaped epidural leads as well as typical cylindrical leads. Benefits and risks exist for both techniques and the exact technique that is optimal depends on surgeon experience and surgeon and patient preference. Complications are rare and can be minimized and managed with appropriate preoperative mitigation.

Influence of convective conditions on the peristaltic mechanism of power-law fluid through a slippery elastic porous tube with different waveforms

PurposeThe purpose of this paper is to emphasize the peristaltic mechanism of power-law fluid in an elastic porous tube under the influence of slip and convective conditions. The effects of different waveforms on the peristaltic mechanism are taken into account.Design/methodology/approachThe governing equations are rendered dimensionless using the suitable similarity transformations. The analytical solutions are obtained by using the long wavelength and small Reynold’s number approximations. The expressions for velocity, flow rate, temperature and streamlines are obtained and analyzed graphically. Furthermore, an application to flow through an artery is determined by using a tensile expression given by Rubinow and Keller.FindingsThe principal findings from the present model are as follows. The axial velocity increases with an expansion in the estimation of velocity slip parameter and fluid behavior index, and it diminishes for a larger value of the porous parameter. The magnitude of temperature diminishes with an expansion in the Biot number. The flux is maximum for trapezoidal wave and minimum for the triangular wave when compared with other considered waveforms. The flow rate in an elastic tube increases with an expansion in the porous parameter, and it diminishes with an increment in the slip parameter. The volume of tapered bolus enhances with increasing values of the porous parameter.Originality/valueThe current study finds the application in designing the heart-lung machine and dialysis machine. The investigation further gives a superior comprehension of the peristaltic system associated with the gastrointestinal tract and the stream of blood in small or microvessels.

Evoked Compound Action Potentials to Guide Lead Placement: A Neuromonitoring Technique Case Series

Abstract INTRODUCTION The procedure to place leads on the spinal cord traditionally required patients to be awake for reporting of device-induced paresthesias. Conversely, neuromonitoring using electromyography (EMG) recording determines optimal lead location while the patient is under general anesthesia. These techniques have been compared with regards to safety and efficacy, favoring the use of neuromonitoring1-2We present 7 subjects, incorporating the use of Evoked Compound Action Potential (ECAP) recording from implanted electrodes, using a new SCS system, and comparing the results with EMG recording. METHODS Standard neuromonitoring protocols were employed at 2 institutions Once leads were implanted, stimulation current was increased until the following were observed: ECAP and EMG signal (late response [LR]), and EMG signal on the neuromonitoring EMG electrodes. An x-ray was obtained; postoperative paresthesia testing was performed to assess coverage obtained at different points along the implanted leads. RESULTS Data were obtained from 7 patients, across 2 sites. Onset of EMG signals on implanted electrodes and EMG electrodes correlated. Furthermore, the ratio of current amplitude between EMG onset and ECAP onset (LR: ECAP), on implanted leads, provides a potential estimate of lead laterality and objective lead placement. Whereby a ratio &lt;1 indicates leads are too lateral. This technique was used successfully to place leads under general anesthesia (1 case), without utilizing EMG recording as a dermatomal coverage marker. CONCLUSION Intraoperative recording of ECAPs and EMG signals from implanted leads may facilitate optimized lead placement, without requiring additional equipment and setup. Analysis of ECAP morphology and its relationship with different waveforms could have diagnostic capabilities intraoperatively. This could be correlative with recent results showing the effect of different waveforms on EMG recording.

Investigating effects of serration geometry on milling forces and chatter stability for their optimal selection

Serrated end mills are widely used in the milling processes due to several advantages they offer. Previous studies on serrated tools are limited to methods which predict mechanics and dynamics of milling process using these tools with a specific serration waveform and no comparative work has been reported for different serration geometries in selection, design or optimization of these tools. In this paper, different types of end mills with frequently used serration shapes, i.e. circular, sinusoidal and trapezoidal, are modeled parametrically. The mechanics of milling processes by using serrated end mills are modeled and experimentally verified. The effects of different waveforms on the mechanics of process are investigated where effects of phase shift direction and local cutting angles on milling forces are verified experimentally. Moreover, serration wave shapes are optimized using a Genetic algorithm for reduced milling forces where up to 30% reduction in cutting forces is achieved and the effects of cutting conditions on optimum serration wave shapes are discussed. Finally, the stability performance of the designed optimum serrated tools is compared with the standard ones, and results show that the chatter stability performance of the optimized tools is enhanced significantly.

A mathematical model of the locomotion of bacteria near an inclined solid substrate: effects of different waveforms and rheological properties of couple-stress slime

Morphological mutations in bacterial cell make them the most miscellaneous microscopic group. Their non-flagellated species known as gliding bacteria exhibit self-powered motion and leave an adhesive trail of slime. The self-propelled motion in some gliding bacteria is achieved as a result of backward surface wave in the cell envelope. Motivated by this fact, an undulating surface on a layer of couple-stress fluid is used to model the motion of such gliding bacteria. Five different wave profiles, namely, sawtooth, sinusoidal, triangular, trapezoidal, and square profiles are used to model the waveform of the undulating wave in the outer cell surface. The inclination of the surface is also integrated into the model. The flow equations are set up under the lubrication assumption. Stream function is derived as an elementary function of an organism’s speed, undulation amplitude, and couple-stress parameter with its flow rate. Speed of the glider and flow rate (satisfying equilibrium conditions) are computed by employing modified Newton–Raphson method. These refined values are further utilized to compute the power dissipation. Effects of different waveforms, inclination angle, gravitational and couple-stress parameters on the speed of the microorganism and rate of energy expended are also quantified. Slime velocity is also plotted for fixed glider. In addition, making use of the obtained realistic set of values of the organism’s speed, flow rate, occlusion parameter, and couple-stress parameter, streamline patterns of the slime are plotted and discussed in detail.

The Effects of Different Waveforms and Frequency Values in Pre-slaughter Stunning by Electricity on Some Welfare Parameters and Carcass Defects

Amaç: Bu çalışmada, etlik piliçlerin kesim öncesi bilinçsizleştirilmesi için farklı dalga tipi ve frekans değerlerini içeren elektrik akımı uygulamasının, refah parametreleri ve karkas kusurları üzerindeki etkileri incelenmiştir.Materyal ve Metot: Çalışmada, 43 günlük toplam 180 (90♀-90♂) etlik piliç, her biri 20 (10♀-10♂) pilice sahip 9 gruba ayrılmıştır. Uygulama grupları, elektrik uygulanmayan kontrol grubu ve elektrik akımıyla bilinçsizleştirilen 8 deneme grubundan oluşmaktadır. Piliçler 50, 200, 400 ve 1000 Hz’lik frekanslarda, 120 mA’lik sinüs dalgalı alternatif (AC) ve pulslanmış doğru akımlar (pDC) ile su banyosunda bilinçsizleştirilmiştir. Elektrik uygulamasından sonra piliçlerin durumunu ortaya koymak için, elektrokardiyogram (EKG) kayıtları alınmıştır. Bunun yanı sıra, piliçlerde nefes alma, kanat çırpma, titreme ve kalp fibrilasyon tepkileri ve göz, ibik ve ayak refleksleri de belirlenmiştir. Kanama sırasında piliçlerdeki kan kaybı ölçülmüştür. Ayrıca, karkas kusurları da değerlendirilmiştir.Bulgular: Bilinçsizleştirme için uygulanan elektrik akımı piliçlerin göz, ibik ve ayak reflekslerini, kanat çırpma davranışını ve solunumunu önemli şekilde etkilemiştir (P&amp;lt;0.05). Elektrikle bayıltma genel olarak etlik piliçlerde karkas kusurlarını artırmıştır. Elektrik uygulamasından kaynaklanan karkas kusurları etlik piliçlerde kanatların orta kısmında ve butlarda spot kanamalar şeklinde meydana gelmiştir (P&amp;lt;0.05). Sonuç: Araştırma sonuçları, piliçlerin AC akımın 50 ve 200 Hz’lik frekanslarda daha etkili bir şekilde bilinçsizleştirildiğini göstermiştir.

Comparison of the effects of 1 MHz and 3 MHz therapeutic ultrasound on endothelium-dependent vasodilation of humans: a randomised clinical trial

ObjectiveTo compare the effects of different waveforms of 1MHz and 3MHz therapeutic ultrasound on endothelial function in healthy subjects. DesignRandomised placebo-controlled, crossover study with concealed allocation and assessor blinding. SettingImaging Centre of the University Hospital. ParticipantsThirty volunteers aged between 18 and 35 years were divided into two homogeneous groups (1MHz and 3MHz). InterventionsContinuous (CUT; 0.4W/cm2SATA), pulsed (PUT; 20% duty cycle, 0.08W/cm2SATA) and placebo waveforms (equipment off) of ultrasound (1MHz and 3MHz) were randomized and applied over the brachial artery for 5minutes. Main outcome measuresEndothelial function was evaluated using the flow-mediated dilation (FMD) technique. ResultsBoth 1MHz [CUT: mean difference 4%, 95% confidence interval (CI) 2 to 6%, P<0.001; PUT: mean difference 4%, 95% CI 2 to 6%, P<0.001] and 3MHz (CUT: mean difference 4%, 95% CI 2 to 6%, P<0.001; PUT: mean difference 4%, 95% CI 2 to 6%, P<0.001) of therapeutic ultrasound increased %FMD by approximately 4% compared with the placebo waveforms. The endothelium-dependent vasodilator responses were the same for both types of waves and frequencies. No differences in baseline diameter, hyperaemic flow, and nitroglycerin-mediated diameter and vasodilation were observed between groups. ConclusionBoth CUT and PUT ultrasound waveforms improved endothelial function. The 1MHz and 3MHz frequencies of therapeutic ultrasound led to similar improvement in endothelial function in healthy volunteers.Clinical trial registration number RBR-4z5z3t.

Effects of Different Waveforms on the Performance of Active Capillary Dielectric Barrier Discharge Ionization Mass Spectrometry.

Active capillary dielectric barrier discharge ionization (DBDI) is emerging as a compact, low-cost, and robust method to form intact ions of small molecules for detection in near real time by portable mass spectrometers. Here, we demonstrate that by using a 10kHz, ~2.5 kVp-p high-voltage square-wave alternating current plasma, active capillary DBDI can consume less than 1μW of power. In contrast, the power consumed using a sine and triangle alternating current waveform is more than two orders of magnitude higher than that for the square waveform to obtain a similar voltage for plasma generation. Moreover, the plasma obtained using a square waveform can be significantly more homogenous than that obtained using sine and triangle waveforms. Protonated dimethyl methylphosphonate (DMMP) and deprotonated perfluorooctanoic acid (PFOA) can be detected at about the same or higher abundances using square-wave DBDI mass spectrometry compared with the use of sine and triangle waveforms. By use of benzylammonium thermometer ions, the extent of internal energy deposition using square, sine, or triangle waveform excited plasmas are essentially the same at the optimum voltages for ion detection. Using an H-bridge circuit driving a transformer optimized to reduce losses, square-wave active capillary DBDI can be continuously powered for ~50h by common 9V-battery (PP3). Graphical Abstract ᅟ.

Microstructure and properties of electroformed nickel under different waveform conditions

In order to prepare electroformed nickel with excellent properties, the effect of different waveforms on microstructure and mechanical properties was investigated by optical microscopy (OM), X-ray diffraction (XRD) and tensile test, respectively. The results show that the samples are composed of micron columnar grains with high-density nanoscale coherent twin boundaries which are parallel to the growth plane. The tensile strength and elongation display opposite tendency with the increase in current density when direct current (DC) electroforming was applied. However, under the condition of pulse current (unidirectional, bidirectional) electroforming, the change regulation of tensile strength and elongation is close while cathode (peak, positive peak) current density increases. XRD results show that electroformed nickel layers with high purity are all fcc crystal configuration under different conditions of the current waveform. The nickel layers formed under bidirectional pulse current behave superior global performance with tensile strength of 692.0 MPa and elongation of 27.6 %.

Simulation of lightning strike damage in carbon nanotube doped CFRP composites

This study focuses on understanding the damage behavior caused by the lightning strike of carbon nanotube (CNT) doped carbon fiber reinforced plastic (CFRP) composites. Quasi isotropic CFRP laminated composite plates used in aerospace structures are modeled to investigate behavior of lightning strike damage. Abaqus finite element program is used in the analysis to study the effect of different waveforms and peak currents. First coupled electrical and thermal analysis is carried out using multi-physics, the results of which are verified with the experimental data obtained in open literature. In the next step, it is assumed that CNTs in different weight percentage are added to resin and the electrical properties of the CFRP plate are updated to run coupled thermal electrical analysis. The results show that the damage area in each ply and the depth of the damage are not linear under the effect of either different waveforms or maximum strike currents. When the weight percentage of CNT doped into the resin increases, the damage region substantially decreases because the electrical conductivity through the thickness of the plate plays significant role for the lightning strike damage.

Effect of Pulsatile Flow Waveform and Womersley Number on the Flow in Stenosed Arterial Geometry

The salient hemodynamic flow features in a stenosed artery depend not only on the degree of stenosis, but also on its location in the circulatory system and the physiological condition of the body. The nature of pulsatile flow waveform and local Womersley number vary in different regions of the arterial system and at different physiological state, which affects the local hemodynamic wall parameters, for example, the wall shear stress (WSS) and oscillatory shear index (OSI). Herein, we have numerically investigated the effects of different waveforms and Womersley numbers on the flow pattern and hemodynamic parameters in an axisymmetric stenosed arterial geometry with 50% diametral occlusion. Temporal evolution of the streamlines and hemodynamic parameters are investigated, and the time-averaged hemodynamic wall parameters are compared. Presence of the stenosis is found to increase the OSI of the flow even at the far-downstream side of the artery. At larger Womersley numbers, the instantaneous flow field in the stenosed region is found to have a stronger influence on the flow profiles of the previous time levels. The study delineates how an approximation in the assumption of inlet pulsatility profile may lead to significantly different prediction of hemodynamic wall parameters.

Numerical Analysis of Alternating Current Voltammetry: Identifiability, Parameter Selection and Experimental Design

This paper describes a numerical analysis of the parametric identifiability of electrochemical systems. First, we analyze global identifiability of the entire set of parameters in a single alternating current voltammetry experiment and examine the effect of different waveforms (square, sawtooth) on the accuracy of the identification procedure. The analysis of global identifiability is equivalent to finding a global optimum of a specially designed function. The optimization problem is solved by a random search method, and a statistical analysis of the obtained solution allows for selection of a subset of the parameters (or their linear combinations), which can be identified. Finally, we discuss optimization of the waveform for better identifiability.