Consecutive Pulses Research Articles

Selective stimulation of nociceptive small fibers during intraepidermal electrical stimulation: Experiment and computational analysis.

Electrical stimulation of skin nociceptors is gaining attention in pain research and peripheral neuropathy diagnosis. However, the optimal parameters for selective stimulation are still difficult to determine because they require simultaneous characterization of the electrical response of small fibers (Aδ- and C-fibers). In this study, we measured the in vivo electrical threshold responses of small fibers to train-pulse stimulation in humans for the first time. We also examined selective stimulation via a computational model, which combines electrical analysis, and terminal fiber and synaptic models, including the first cutaneous pain C-fiber model. Selective stimulation of small fibers is performed by injecting train-pulse stimulation via coaxial electrodes with an intraepidermal needle tip at varying pulse counts and frequencies. The activation Aδ- or C-fibers was discriminated from the differences in reaction time. Aδ-fiber elicited a pinpricking sensation with a mean reaction time of 0.522 s, and C-fiber elicited a tingling sensation or slight burning itch with a mean reaction time of 1.243 s. The implemented multiscale electrical model investigates synaptic effects while considering stimulation waveform characteristics. Experimental results showed that perception thresholds decreased with the number of consecutive pulses and frequency up to convergence (five pulses or 70 Hz) during the selective stimulation of Aδ- and C-fibers. Considering the synaptic properties, the optimal stimulus conditions for selective stimulation of Aδ- vs. C-fibers were train of at least four pulses and a frequency of 40-70 Hz at a pulse width of 1 ms. The experimental results were modeled with high fidelity by incorporating temporal synaptic effects into the computational model. Numerical analysis revealed terminal axon thickness to be the most important biophysical factor affecting threshold variability. The computational model can be used to estimate perception thresholds while understanding the mechanisms underlying the selective stimulation of small fibers. The parameters derived here are important in exploring selective stimulation between Aδ- and C-fibers for diagnosing neuropathies.

Random-modulated pulse lidar using a gain-switched semiconductor laser with a delayed self-homodyne interferometer.

We propose the generation of random-modulated pulses using a gain-switched semiconductor laser with a delayed self-homodyne interferometer (DSHI) for lidar applications. By emitting non-repetitive random-modulated pulses, ambiguity in ranging and interference in detection can be mitigated. When gain-switched, the wavelength of the laser fluctuates abruptly at the beginning of the pulse and then drops until it stabilizes toward its continuous-wave (CW) state. By beating the two pulses with instantaneous frequency detuning from the DSHI, pulses consisting of random and down-chirped modulations can be generated without any complex code generation and modulation. In this study, we investigate the waveforms and spectra of the random-modulated pulses generated under various homodyne delay lengths, switching currents, and pulsewidths. We characterize their signal-to-noise ratio (SNR), precision, and cross-correlation between consecutive pulses to evaluate their performance in lidar applications. For a good SNR of over 12 dB, the generated pulses have an optimal precision of approximately 1 mm in ranging, which is substantially better than the chaos-modulated pulses generated based on laser feedback dynamics. By establishing a random-modulated pulse lidar based on the proposed gain-switched homodyne scheme, we successfully demonstrate 3D imaging and profiling with good precision.

A Chaotic Pulse Train Generator Based on Henon Map

The Henon map forms one of the most-studied two-dimensional discrete-time dynamical systems that exhibits chaotic behavior. The Henon map takes a point in the plane and maps it to a new point . In this paper, a chaotic pulse generator based on the chaotic Henon map is proposed. It consists of a Henon map function subcircuit to realize the Henon map and another subcircuit to perform the iterative operation. The Henon map subcircuit comprises operational amplifiers, multipliers, delay elements and resistors, whereas, the iterative subcircuit is implemented with a simple design that comprises of an edge forming circuit followed by a monostable multivibrator and a voltage controlled switch without the use of any clock control. The proposed design can be used to realize the Henon map and also to generate a chaotic pulse train, with a controllable time interval and pulse position. The proposed circuit is implemented and simulated using Multisim 13.0 and MATLAB R2019b. The chaotic nature of the generated pulse train and also the time interval between the consecutive pulses is verified by the calculation of its Lyapunov exponents.

Characterization of PDIV, PDEV, and RPDIV in Insulated Wires Under Unipolar Repetitive Square Wave Excitations for Inverter-Fed Motors

The behaviour of partial discharge inception voltage (PDIV), partial discharge extinction voltage (PDEV) and repetitive partial discharge inception voltage (RPDIV) as a function of exposure/poling time under unipolar repetitive square wave excitations at atmospheric pressure (1013 mbar) is experimentally measured and investigated. The partial discharge (PD) tests are performed on two commercially available insulated wires: Glass fibre as Type II and Polyether Ether Ketone (PEEK) as Type I insulated wires used in inverter-fed motors. The impact of excitation polarity, pulse repetition frequency and rise time on the PD quantities (i.e., PDIV, PDEV and RPDIV) is studied as a function of stressing duration. In addition, the trend of RPDIV and PDIV dispersion levels are compared as a function of poling time under positive and negative unipolar excitations with two rise times (i.e., 80 and 800 ns) and two pulse repetition frequencies (i.e., 50 Hz and 2.5 kHz), relying on the shape/slope parameter of the Weibull distribution. The collected data shows that the electric field induced by the interface charge deposited by PD occurring during consecutive pulses and the space charge accumulation in the insulation bulk plays a decisive role in PD quantities’ variations under unipolar repetitive square wave excitations.

Focal Irreversible Electroporation for Localized Prostate Cancer - Oncological and Safety Outcomes Using mpMRI and Transperineal Biopsy Follow-Up.

Irreversible electroporation (IRE) technology for prostate cancer (PC) generates consecutive electrical pulses between pairs of electrodes which move through tumorous cells, irreversibly perforate their membranes and eventually lead to cell death, while avoiding tissue thermal effect. The technique is used for primary focal lesions as well as for focal salvage cases. This series reports short term oncological control, quality of life and safety results. Retrospective data were collected from 45 consecutive cases of primary (N=38) and salvage (N=7) PC patients treated with IRE. All patients had transperineal MRI/US fusion biopsy and PET-PSMA scan prior to treatment, to verify single lesion. Transperineal Nano-Knife IRE system was used in day-care theatre. Patients had 6 months mpMRI, blood PSA and 1 year confirmatory biopsy following procedure. Quality of life was recorded during the first year. Median primary subgroup analysis (N=38): age 69 years, initial PSA 5.6 ng/dL, lesion size 0.8 mL and ISUP Group 2 (1-3). Median salvage subgroup analysis (N=7): age 76 years, initial PSA 11.9 ng/dL, lesion size 2.0 mL and ISUP Group 4 (1-5). Median catheter time 5 (3-7) days. No Clavien-Dindo>1 complications were reported nor re-admissions, incontinence, strictures or fistulas. 5% of patients were given PDE-5i drugs. Primary group PSA dropped by 39%, mpMRI clearance in 84%, out-field new lesion in 12%, in-field lesion in 4%. Biopsy at 1 year: 4 patients had out-field clinically significant PC, thus 3 had re-IRE and 1 had radiation therapy. Salvage subgroup MRI clearance was 60%, and 52% remained on active surveillance by 1 year. IRE treatment for focal PC is safe for primary and salvage cases, if done by a meticulously skilled and trained team, and under strict protocols. The short term oncological results are promising especially for primary lesions. Long term oncological results will be published over time.

Pulsed Production of Antihydrogen in AEgIS

Low-temperature antihydrogen atoms are an effective tool to probe the validity of the fundamental laws of Physics, for example the Weak Equivalence Principle (WEP) for antimatter, and -generally speaking- it is obvious that colder atoms will increase the level of precision. After the first production of cold antihydrogen in 2002 [1], experimental efforts have substantially progressed, with really competitive results already reached by adapting to cold antiatoms some well-known techniques pre- viously developed for ordinary atoms. Unfortunately, the number of antihydrogen atoms that can be produced in dedicated experiments is many orders of magnitude smaller than of hydrogen atoms, so the development of novel techniques to enhance the production of antihydrogen with well defined (and possibly controlled) conditions is essential to improve the sensitivity. We present here some experimental results achieved by the AEgIS Collaboration, based at the CERN AD (Antiproton Decelerator) on the production of antihydrogen in a pulsed mode where the production time of 90% of atoms is known with an uncertainty of ~ 250 ns [2]. The pulsed antihydrogen source is generated by the charge-exchange reaction between Rydberg positronium (Ps*) and an antiproton (p¯): p¯ + Ps* → H¯* + e−, where Ps* is produced via the implantation of a pulsed positron beam into a mesoporous silica target, and excited by two consecutive laser pulses, and antiprotons are trapped, cooled and manipulated in Penning-Malmberg traps. The pulsed production (which is a major milestone for AEgIS) makes it possible to select the antihydrogen axial temperature and opens the door for the tuning of the antihydrogen Rydberg states, their de-excitation by pulsed lasers and the manipulation through electric field gradients. In this paper, we present the results achieved by AEgIS in 2018, just before the Long Shutdown 2 (LS2), as well as some of the ongoing improvements to the system, aimed at exploiting the lower energy antiproton beam from ELENA [3].

Parametric amplification as a single-shot time-resolved off-harmonic probe for laser–matter interactions

Abstract An optical probing of laser–plasma interactions can provide time-resolved measurements of plasma density; however, single-shot and multi-frame probing capabilities generally rely on complex setups with limited flexibility. We have demonstrated a new method for temporal resolution of the rapid dynamics ( $\sim 170$ fs) of plasma evolution within a single laser shot based on the generation of several consecutive probe pulses from a single beta barium borate-based optical parametric amplifier using a fraction of the driver pulse with the possibility to adjust the central wavelengths and delays of particular pulses by optical delay lines. The flexibility and scalability of the proposed experimental technique are presented and discussed.

Studies of event burst phenomenon with SiPMs in liquid nitrogen

Silicon photomultiplier (SiPM) are used to collect scintillation photons in many cryogenic noble liquid detectors deployed around the world, such as DarkSide, nEXO, MEGII, ProtoDUNE and DUNE. An event burst phenomenon was observed during routine characterization on many models of SiPMs operated in liquid nitrogen. These bursts of consecutive pulses are initiated by an intense dark photoelectron pulse with an event rate much lower than the time-uncorrelated thermal dark pulse. Although the rate of these burst events is very low, it can potentially compromise some dedicated rare physics event searches which are also anticipated to be of extremely low rate. Here, we systematically studied the behavior of the event burst phenomenon and identified the probable cause of the phenomenon. This investigation is important for the selection of SiPMs for use in noble liquid detectors, high energy physics experiments, and industrial applications where SiPMs are used in cryogenic environment.

Two-dimensional Cs3Bi2I6Cl3 perovskite for resistive switching behaviors and artificial synaptic simulation

Two-dimensional Cs3Bi2I6Cl3 perovskite films have been successfully grown on indium tin oxide (ITO) glass substrates, which were used to fabricate the memory device with the structure of Al/Cs3Bi2I6Cl3/ITO. The current memristor exhibited bipolar resistive switching behaviors. Both the endurance and retention time tests clearly demonstrate the excellent stability of the present device. Moreover, the short-term plasticity of biological synapse was successfully simulated by evaluating the conductance responses of Al/Cs3Bi2I6Cl3/ITO device under applying various voltage pulses in detail. The enhancement of conductance triggered by 10 consecutive pulses (−0.5 V, 10 ms) was up to be around 40% compared to the resting conductance level. The simulations of long-term plasticity for biological synapse were also performed through spike-timing-dependent plasticity. The fitted time constants are 8.38 and 6.89 ms for long-term potentiation and long-term depression, respectively, which are comparable to the millisecond-scale response time in biological synapses. In addition, based on the photoelectric response ability, the current Al/Cs3Bi2I6Cl3/ITO device established associative learning behavior successfully by simulating the Pavlov’s dog experiment. The present Al/Cs3Bi2I6Cl3/ITO device is promising to be used for resistive switch and biological synaptic simulation of next generation memristors.

Enhanced Synaptic Features of ZnO/TaOx Bilayer Invisible Memristor for Brain-Inspired Computing

In this letter, we present a transparent bilayer ZnO/TaOx memristive synapse for brain-inspired computing. The device shows excellent AC endurance ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{{9}}$ </tex-math></inline-formula> cycles) and high-temperature retention ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{{4}}$ </tex-math></inline-formula> s) without any degradation at 100 °C. The device exhibits highly stable repetitive 5130 potentiation (P) and depression (D) epochs with 1.026 M pulses. The multilevel characteristics (MLC) of the device are achieved by changing the pulse height from 0.7 to 1.1 V for long-term potentiation (LTP) and from −0.9 to −1.3 V for long-term depression (LTD) having gradual conductance change for both P and D cases. The synaptic features such as paired-pulse facilitation (PPF) and spike time-dependent plasticity (STDP) are measured using consecutive AC pulses. These unique features confirm that the synaptic device has excellent capability for the application in the brain-inspired computing systems.

Li-Ion Doped Artificial Synaptic Memristor for Highly Linear Neuromorphic Computing

Linear weights modulation in neuromorphic memristor plays an important role in high-accuracy image recognition task. Herein, a Li+ doped organic artificial memristor for neuromorphic computing was proposed for linear weights update, which shows active ions diffusive dynamics as Ca2+ diffusion in biological synapse. The memristor exhibits gradual resistive switching, multi-state storage and typical synaptic behaviors. In addition, the synaptic learning capability of letter “T” was demonstrated in a memristors array. By designing consecutive pulse waveforms with enhanced amplitude, the linearity of memristor for weight update in long-term potentiation and depression (LTP/LTD) could be improved from 6.8 to 0.4. Based on the great nonlinearity factor in LTP ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\alpha _{\text {p}}={1.5}$ </tex-math></inline-formula> ) and LTD ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\alpha _{\text {d}}={0.4}$ </tex-math></inline-formula> ), face recognition was achieved with high accuracy of 96% by artificial neural network consisting of ion doped memristors. The ion doped organic memristor with highly linear weights update provides guidelines for the development of bio-inspired ion diffusive neuromorphic computing system.

Characterization of pulsed light for microbial inactivation

Pulsed light is an emerging technology that can serve as an alternative to current antimicrobial interventions in the food industry. The first objective of this study was to define the spectrum and energy characteristics of pulsed light. The second objective was to establish the germicidal response of Escherichia coli , Salmonella enterica subsp. enterica ser. Typhimurium, Listeria monocytogenes , Bacillus cereus (vegetative cells and endospores), Aspergillus niger spores, and Penicillium roqueforti spores were evaluated following pulsed light treatments. Microorganisms were treated using three different broad-spectrum xenon gas flashlamps (Type A: 380–1100 nm, Type B: 235–1100 nm, and Type C: 190–1100 nm) for up to 15 pulses. All microorganisms experienced a significant interaction of flashlamp type × treatment duration (P < 0.0001). Additionally, E. coli was treated with pulsed light with flashlamp type B using light filters to block ultraviolet light and selectively deliver visible (VIS; 380–740 nm), near-infrared (NIR; 700–1080 nm), and VIS-NIR (400–1080 nm) radiation to the cells. The filter type × treatment duration interaction was significant (P < 0.0001). The VIS, NIR, and VIS-NIR filter treatments achieved modest reductions of 0.72, 0.19, and 0.83 Log 10 CFU/mL, respectively, after 75 consecutive pulses. To visualize physical effects on cell structures, transmission electron microscopy (TEM) images were obtained for E. coli following 15 pulse treatments of the three flashlamp types and the type B flashlamp with VIS-NIR filter placement. TEM imaging indicated that damage to cell morphology following treatment by broad-spectrum radiation was negligible. These results indicate that microbial sensitivity to pulsed light treatment differs for species and is predominantly attributed to the ultraviolet portion of the spectrum. • Pulsed light treatment susceptibility differs for Gram -, Gram +, and spores/fungi. • Microbial inactivation by pulsed light is predominantly attributed to UV light. • Visible and near-infrared radiation contribute negligibly to microbe inactivation. • Pulsed light treatment imparts negligible effects to Escherichia coli morphology.

Particle Production in Strong Electromagnetic Fields and Local Approximations

We investigate the phenomenon of electron–positron pair production in intense external backgrounds within the strong-field regime. We perform nonperturbative calculations by solving the quantum kinetic equations, and obtain the momentum distributions of particles created and the total number of pairs. In particular, we analyze the validity of the locally constant field approximation (LCFA), which represents a powerful method for treating inhomogeneous external backgrounds. We consider a combination of two consecutive time-dependent Sauter pulses and thoroughly examine the effects of quantum interference and the role of the Pauli exclusion principle. It is shown that the latter can be approximately incorporated within the LCFA when computing the momentum distributions, while the closed-form LCFA expression for the total particle yield completely disregards Pauli blocking. It is demonstrated that in the presence of multiple turning points of classical electron trajectories, one observes interference patterns in the particle spectra, and the LCFA may significantly overestimate the number of pairs. To further elaborate this issue, we perform the analogous calculations in the case of scalar QED. It is shown that the quantum statistics effects enhance the number of bosons produced.

Histone deacetylase 4 and 5 translocation elicited by microsecond pulsed electric field exposure is mediated by kinase activity.

Electroporation-based technologies using microsecond pulsed electric field (µsPEF) exposures are established as laboratory and clinical tools that permeabilize cell membranes. We demonstrate a µsPEF bioeffect on nucleocytoplasmic import and export of enzymes that regulate genetic expression, histone deacetylases (HDAC) -4 and -5. Their μsPEF-induced nucleocytoplasmic transport depends on presence and absence of extracellular calcium ions (Ca2+) for both MCF7 and CHO-K1 cells. Exposure to 1, 10, 30 and 50 consecutive square wave pulses at 1Hz and of 100µs duration with 1.45kV/cm magnitude leads to translocation of endogenous HDAC4 and HDAC5. We posit that by eliciting a rise in intracellular Ca2+ concentration, a signaling pathway involving kinases, such as Ca2+/CaM-dependent protein kinase II (CaMKII), is activated. This cascade causes nuclear export and import of HDAC4 and HDAC5. The potential of µsPEF exposures to control nucleocytoplasmic transport unlocks future opportunities in epigenetic modification.

Local crystallization in amorphous Fe80Si11B9 ribbon by pulsed laser interference heating

Pulsed laser (Q-switched Nd:YAG) interference heating was used to create periodically distributed, crystallized, micro-areas, ∼10 μm in diameter within the amorphous matrix on Fe80Si11B9 alloy. Laser energy and a number of consecutive pulses were varied as controlled parameters of this study. The influence of such interference heating, on the resulting microstructure, magnetic domain structure and magnetic field was examined. TEM analysis showed that crystallized surface layer of the sample after pulsed laser heating consists of α-Fe(Si) nanocrystals embedded in the amorphous matrix. Research, using the Fresnel imaging (defocus mode) showed that the nanocrystallization of the amorphous alloy caused a significant refinement of the magnetic domain structure, as compared to amorphous state. The electron holography images show that the α - Fe(Si) crystallites introduce additional distortion of the magnetic field lines in the sample. The effects of an external magnetic field were studied by examining the configuration of the phase shift contours as a function of its magnitude.

Controlling bubble generation by femtosecond laser-induced filamentation

Femtosecond laser-induced optical breakdown in liquids results in filamentation, which involves the formation and collapse of bubbles. In the present work, we elucidate spatio-temporal evolution, interaction, and dynamics of the filamentation-induced bubbles in a liquid pool as a function of a broad spectrum of laser pulse energies (∼1 to 800 µJ), liquid media (water, ethanol, and glycerol), and the number of laser pulses. Filament attributes such as length and diameter have been demarcated and accurately measured by employing multiple laser pulses and were observed to have a logarithmic dependence on laser energy, irrespective of the medium. The size distribution of persisting microbubbles is controlled by varying the pulse energy and the number of pulses. Our experimental results reveal that introducing consecutive pulses leads to strong interaction and coalescence of the pulsating bubbles via Bjerknes force due to laser-induced acoustic field generation. The successive pulses also influence the population density and size distribution of the micro-bubbles. We also explore the size, shape, and agglomeration of bubbles near the focal region by controlling the laser energy for different liquids. The insights from this work on filamentation-induced bubble dynamics can be of importance in diverse applications such as surface cleaning, fluid mixing and emulsification, and biomedical engineering.

Noncontrast time-resolved pulmonary magnetic resonance angiography with consecutive beam saturation pulse and variable flip angles using three-dimensional fast spin echo: A preliminary study

To develop and validate a novel noncontrast time-resolved magnetic resonance angiography (NC TR-MRA) using consecutive beam pulses with variable flip angles for visualizing hemodynamics in the pulmonary artery, we performed phantom and volunteer studies and applied the novel NC TR-MRA to a 51-year-old woman with pulmonary arteriovenous malformation (PAVM).The novel NC TR-MRA sequence utilized consecutive multiple-beam saturation pulses with variable flip angles considering venous blood T1 relaxation to alter the visualized blood signal length. The flowing blood signal length is suppressed according to the number of beam saturation pulses. NC TR-MRA in each flow phase was assessed by subtracting the images with and without beam saturation pulses. In the flow phantom study, three flow velocities were used to simulate physiological pulmonary arterial blood flow. Signal profiles along the flow direction were evaluated in each flow phase. In the volunteer study, five healthy volunteers were recruited, and NC TR-MRA was applied to evaluate relationships between the flow-saturated time and signal enhancement rates. Four regions of interest (ROIs) were determined on the proximal and distal portions of the right basal artery. A patient with PAVM was included to validate whether a PAVM lesion could be visualized using NC TR-MRA. The visualized flow signal lengths extended proportionally with the number of beam saturation pulses in the steady-flow phantom at all velocities. In the volunteer study, NC TR-MRA images showed signal enhancement from the proximal to distal portions of the right basal artery with increase in the flow-saturated time. Signal enhancement rates in all ROIs were significantly positively correlated with the flow-saturated time (p < 0.001 in all ROIs). Further, the lesion and its hemodynamics could be explicitly visualized in the patient with PAVM. Hence, NC TR-MRA using beam saturation pulse can visualize the hemodynamics of the pulmonary artery and may be useful for diagnosing and following patients with PAVM.

Use of Antibacterial Envelopes for Prevention of Infection in Neuromodulation Implantable Pulse Generators.

Neuromodulation unit placement carries a historic infection rate as high as 12%. Treatment of such requires surgical removal and a long course of systemic antibiotics. Antibiotic-impregnated envelopes have been effective in preventing infection in implantable cardiac devices. At our center, 1 surgeon uses these envelopes with all implanted neuromodulation units. To assess the efficacy of antibacterial envelopes in prevention of infection in neuromodulation device placement. We conducted a retrospective cohort study of consecutive implantable pulse generator (IPG) unit implantation with an antibacterial envelope at a single center between October 2014 and December 2019. We collected demographic data, including postoperative infections, reoperations, and complications, associated with the IPGs. This cohort was then compared with a historical cohort of consecutive patients undergoing surgery before envelope usage (October 2007-April 2014). In the pre-envelope cohort of 151 IPGs placed in 116 patients, there were 18 culture-confirmed infections (11.9%). In the antibacterial envelope cohort of 233 IPGs placed in 185 patients, there were 5 culture-confirmed infections (2.1%). The absolute risk reduction of the antibacterial envelope was 9.85% (95% CI 4.3%-15.4%, P &lt; .01). The number needed to treat was 10.1 (95% CI 6.5-23.1, P &lt; .01) envelopes to prevent 1 IPG infection. We saw a reduced rate of infections in the antibacterial envelope cohort. Although this is likely multifactorial, our results suggest a benefit of antibacterial envelopes on infection after neuromodulation surgery.

IMPROVING THE SIMULATION ALGORITHM FOR THE WORK PROCESS OF PENDULUM-BASED TENSILE STRENGTH TESTING MACHINE

Article considers approaches to improve the functioning of tensile strength testing machine K-1, based on modelling the mechanical and informational processes of its operation. The pendulum movement registration process is analysed in detail, resulting in a set of restrictions imposed on data processing methods used during simulation. Based on this, a set of recommendations is developed, regarding the correct way to track pendulum’s motion. It is suggested to register intervals between consecutive encoder pulses, rather than independently poll encoder’s current position using a timer. Based on this idea, a simulation algorithm is developed that allows for a close reproduction of the properties of the data gathered during experiment. This algorithm is implemented in a software system. The data produced by this system closely resembles the data gathered during experiments with a real device. As such, the model and the algorithm can be used to develop a quality control system for the K-1 machine.

Reducing Pumping Power Consumption by Pulsed Operation?

Abstract A computational study, based on exact solutions for transient laminar flow in pipes and on an empirical correlation for transition to turbulence in the presence of temporal acceleration, shows that, provided certain conditions are met, pumping an incompressible fluid at a prescribed flow rate by a series of consecutive pressure gradient pulses may require less mechanical power consumption than pumping the same flow rate under steady-state turbulent flow conditions. The reason is that, in the former case, the fluid is pumped under conditions of accelerated laminar flow, for which the onset of turbulence occurs at Reynolds numbers much larger than the steady-state critical value of ∼2,100. The conclusions of this study rest crucially on the exact criterion for transition to turbulence in accelerated laminar flow, for which, unfortunately, existing experimental results exhibit a large scatter and general consensus is still lacking. Also, this study adopts a simplified description of the problem, and further model refinements, design efforts, and supporting experimental tests will have to be performed before the hypothesis that pulsed pumping can provide energetic advantages can be demonstrated in “real-world” situations.