Journal articles on the topic 'Transient'
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Omel’chenko, Oleh E., and Tamás Tél. "Focusing on transient chaos." Journal of Physics: Complexity 3, no. 1 (March 1, 2022): 010201. http://dx.doi.org/10.1088/2632-072x/ac5566.
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Abstract Recent advances in the field of complex, transiently chaotic dynamics are reviewed, based on the results published in the focus issue of J. Phys. Complex. on this topic. One group of achievements concerns network dynamics where transient features are intimately related to the degree and stability of synchronization, as well as to the network topology. A plethora of various applications of transient chaos are described, ranging from the collective motion of active particles, through the operation of power grids, cardiac arrhythmias, and magnetohydrodynamical dynamos, to the use of machine learning to predict time evolutions. Nontraditional forms of transient chaos are also explored, such as the temporal change of the chaoticity in the transients (called doubly transient chaos), as well as transients in systems subjected to parameter drift, the paradigm of which is climate change.
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Gibson, Toby J., Markus Seiler, and Reiner A. Veitia. "The transience of transient overexpression." Nature Methods 10, no. 8 (July 30, 2013): 715–21. http://dx.doi.org/10.1038/nmeth.2534.
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Hine, M. "Transient Synthesis Using a Fourier Transform Envelope: An Alternative to Swept-Sine Vibration Testing." Journal of the IEST 39, no. 5 (September 1, 1996): 17–22. http://dx.doi.org/10.17764/jiet.2.39.5.y736q45216l175r6.
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Transient vibration test offer an alternative to the conventional swept-sine vibration test, with controllable conservatism. A method of deriving a single vibration test transient from several spacecraft flight transients is described. These transients were from different physical locations on the spacecraft. The test transient was derived by taking the inverse Fourier transform of an envelope of the Fourier transforms of the flight transients. The inverse transformation was performed using the real and imaginary parts of that Fourier transform forming the envelope amplitude at each frequency. The test transient therefore has the same frequency content and maximum amplitudes as the flight transients. A generic test transient was therefore produced that duplicates many operating conditions at separate physical locations. It could be applied to many different structural components of a spacecraft, simplifying a vibration test program. The transient vibration test produces significantly less overtest than a conventional swept-sine vibration test.
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Paar, V., N. Pavin, N. Paar, and B. Novaković. "Nonlinear dynamics of a single-degree robot model Part 2: Onset of chaotic transients." Robotica 18, no. 2 (March 2000): 201–8. http://dx.doi.org/10.1017/s0263574799001952.
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In Part 1 of this paper we have investigated numerically the quasiperiodic and frequency locked solutions of mathematical model of a robot with one degree of freedom. In this paper we extend our investigations to the region of transient chaos. The zones of chaotic transients are very broad and lie beyond the parameter range of engineering significance. Transiently chaotic zones exhibit a complex structure, fractally intertwined with tongues of regular pattern and cover a broad range of control parameter L. The crisis point for the onset of sustained chaos lies extremely far from the point of onset of transient chaos.
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Pannila, Earl A. R. L., and Mahesh Edirisinghe. "Characterization of Switching Transients in Low Voltage Power Systems of Tea Factories in Sri Lanka." European Journal of Electrical Engineering 22, no. 4-5 (October 30, 2020): 325–34. http://dx.doi.org/10.18280/ejee.224-504.
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Voltage transients caused by various motors and electrical equipment of tea factories in Sri Lanka have been observed and analyzed. While reporting the major components of transients, this work extends it aspires to investigate the risk of having faults in a three-phase induction motor by monitoring and analyzing the transient voltage waveforms during the starting period. Therefore, common mode transient investigations have been followed. Transient voltage signals have been obtained from high end test setup and altogether 588 waveforms have been analyzed in both the time and frequency domains. In DOL and Star-Delta starting, highest transient amplitude of 688.2 V and 572.1 V have been observed respectively. Highest transient amplitude of 976.4 V and 980.5 V were observed in DOL and Star-Delta switching respectively. Withering and rolling sections dominates over other stages, generating high amplitude transients in average, reflecting same endangerment in energy calculations as presented in voltage integral. DOL starting transients carries fast rise times as 14 ns and in Star-Delta it is 28 ns. In order to assist with the exegesis of these data, transient parameters like rise time, duration, highest peak, etc.… have also been presented in statistical basis.
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McNeer, Richard R., Jorge Bohórquez, and Özcan Özdamar. "Influence of Auditory Stimulation Rates on Evoked Potentials during General Anesthesia." Anesthesiology 110, no. 5 (May 1, 2009): 1026–35. http://dx.doi.org/10.1097/aln.0b013e31819dad6f.
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Background The auditory middle-latency response (transient) and the 40-Hz auditory steady state response (ASSR) are modulated by anesthetics. However, the quantitative relation between these evoked responses is difficult to obtain because of technical limitations of the recording methods used to obtain transients at high stimulation rates. This study uses continuous-loop averaging deconvolution to fill this technical gap and to study the relation between the transient and ASSR waveform during general anesthesia. Methods The authors recorded 5- and 40-Hz transients and 40-Hz ASSRs in 13 subjects during general anesthesia. The 5- and 40-Hz transients were used to predict the 40-Hz ASSR by linearly superimposing the transient waveforms. The predicted and recorded ASSRs were analyzed and compared using phasor and Hotelling T(2) analyses. Results Grand-averaged recordings revealed differences in the early middle-latency peaks between 5- and 40-Hz transients, e.g., the peak P(x) was present only in 5-Hz transient. Only the predicted 40-Hz ASSR derived from the 40-Hz transient matched the actual ASSR. Phasor analysis showed that the early peaks contribute significantly to the steady state waveform, and this explains why 5-Hz transient does not predict the 40-Hz ASSR. Oscillations in both the 5- and 40-Hz transients were observed during anesthesia. Discussion The 40-Hz ASSR represents a composite waveform and arises when transient waveforms elicited with a 40-Hz stimulation rate are overlapped and superimposed. During general anesthesia, the morphology of the transient is dependent on the rate of stimulus presentation. The composite nature of the ASSR may explain nonmonotonic anesthetic dose-response relations observed by others.
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Faria, J. A. Brandão. "Inception of transients and transient suppression methods." International Transactions on Electrical Energy Systems 24, no. 1 (October 17, 2013): 141–52. http://dx.doi.org/10.1002/etep.1818.
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Hastings, Alan, Karen C. Abbott, Kim Cuddington, Tessa Francis, Gabriel Gellner, Ying-Cheng Lai, Andrew Morozov, Sergei Petrovskii, Katherine Scranton, and Mary Lou Zeeman. "Transient phenomena in ecology." Science 361, no. 6406 (September 6, 2018): eaat6412. http://dx.doi.org/10.1126/science.aat6412.
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The importance of transient dynamics in ecological systems and in the models that describe them has become increasingly recognized. However, previous work has typically treated each instance of these dynamics separately. We review both empirical examples and model systems, and outline a classification of transient dynamics based on ideas and concepts from dynamical systems theory. This classification provides ways to understand the likelihood of transients for particular systems, and to guide investigations to determine the timing of sudden switches in dynamics and other characteristics of transients. Implications for both management and underlying ecological theories emerge.
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Gintant, Gary A. "Characterization and functional consequences of delayed rectifier current transient in ventricular repolarization." American Journal of Physiology-Heart and Circulatory Physiology 278, no. 3 (March 1, 2000): H806—H817. http://dx.doi.org/10.1152/ajpheart.2000.278.3.h806.
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Although inactivation of the rapidly activating delayed rectifier current ( I Kr) limits outward current on depolarization, the role of I Kr (and recovery from inactivation) during repolarization is uncertain. To characterize I Krduring ventricular repolarization (and compare with the inward rectifier current, I K1), voltage-clamp waveforms simulating the action potential were applied to canine ventricular, atrial, and Purkinje myocytes. In ventricular myocytes, I Kr was minimal at plateau potentials but transiently increased during repolarizing ramps. The I Kr transient was unaffected by repolarization rate and maximal after 150-ms depolarizations (+25 mV). Action potential clamps revealed the I Kr transient terminating the plateau. Although peak I Kr transient density was relatively uniform among myocytes, potentials characterizing the peak transients were widely dispersed. In contrast, peak inward rectifier current ( I K1) density during repolarization was dispersed, whereas potentials characterizing I K1 defined a narrower (more negative) voltage range. In summary, rapidly activating I Kr provides a delayed voltage-dependent (and functionally time-independent) outward transient during ventricular repolarization, consistent with rapid recovery from inactivation. The heterogeneous voltage dependence of I Kr provides a novel means for modulating the contribution of this current during repolarization.
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Korakianitis, T., J. I. Hochstein, and D. Zou. "Prediction of the Transient Thermodynamic Response of a Closed-Cycle Regenerative Gas Turbine." Journal of Engineering for Gas Turbines and Power 127, no. 1 (January 1, 2005): 57–64. http://dx.doi.org/10.1115/1.1806449.
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Instantaneous-response and transient-flow component models for the prediction of the transient response of gas turbine cycles are presented. The component models are based on applications of the principles of conservation of mass, energy, and momentum. The models are coupled to simulate the system transient thermodynamic behavior, and used to predict the transient response of a closed-cycle regenerative Brayton cycle. Various system transients are simulated using: the instantaneous-response turbomachinery models coupled with transient-flow heat-exchanger models; and transient-flow turbomachinery models coupled with transient-flow heat-exchanger models. The component sizes are comparable to those for a solar-powered Space Station (radial turbomachinery), but the models can easily be expanded to other applications with axial turbomachinery. An iterative scheme based on the principle of conservation of working-fluid mass in the system is used to compute the mass-flow rate at the solar-receiver inlet during the transients. In the process the mass-flow rate of every component at every time step is also computed. Representative results of different system models are compared and discussed.
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Granzier, H. L., A. Mattiazzi, and G. H. Pollack. "Sarcomere dynamics during isotonic velocity transients in single frog muscle fibers." American Journal of Physiology-Cell Physiology 259, no. 2 (August 1, 1990): C266—C278. http://dx.doi.org/10.1152/ajpcell.1990.259.2.c266.
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If the load on a tetanized fiber is abruptly changed to a new steady value, the ensuing fiber length change shows the well-known "isotonic velocity transient," in which the velocity oscillates before settling at some steady value. We studied sarcomere dynamics during these transients using two methods: optical diffraction and a segment-length method. Our principal aim was to determine whether these transients might be a reflection of the fact that sarcomere shortening is often found to be stepwise. We found that pauses in sarcomere shortening occurred during the low-velocity phases of the transient and that steps of sarcomere shortening occurred during the high-velocity phases. Thus the isotonic transient appears to arise from the steps. In addition to the isotonic transient, we studied the well-known isometric transient, in which fiber length is abruptly changed, and ensuing tension response is measured. Again, we found that the transient may be a reflection of the stepwise shortening pattern.
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Zaunschirm, Markus, Joshua D. Reiss, and Anssi Klapuri. "A Sub-Band Approach to Modification of Musical Transients." Computer Music Journal 36, no. 2 (June 2012): 23–36. http://dx.doi.org/10.1162/comj_a_00117.
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The transient modifier is a type of audio effect that changes the level of the transient parts in a musical signal while leaving the steady-state parts unchanged. This article presents a high-performance algorithm for transient detection and modification, one that is capable of modifying transients in polyphonic or multi-voiced signals, and capable of modifying both hard (percussive) and soft (non-percussive) transients. The detection and modification of transients are performed in the frequency-domain using a sub-band approach. Detection is based on both phase and energy information using an adaptive threshold, and modification is carried out independently at each sub-band. The performance of the proposed sub-band approach was compared with other transient-modification algorithms using subjective listening tests. We show that the sub-band approach with adaptive threshold mostly outperforms other approaches.
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Tonry, J. L. "Pan-STARRS, ATLAS and optical transient searches." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 371, no. 1992 (June 13, 2013): 20120269. http://dx.doi.org/10.1098/rsta.2012.0269.
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The Pan-STARRS1 survey is collecting multi-epoch, multi-colour observations of the sky north of declination −30 ° , and has designated 70 deg 2 for nightly observations that are particularly useful for transient detection. A duplicate, Pan-STARRS2, is nearing completion that offers opportunities to improve the quality of transient search and observation, as well as simply increasing the number of detections. A new system, the Asteroid Terrestrial-impact Last Alert System (ATLAS), increases the search area to all-sky in return for diminished sensitivity, and highlights tension among optimization for static sky images, optimization for faint transients and optimization for an unbiased number of transients. ATLAS gives up sub-arcsecond images and full colour information to specialize in the third category, but should detect many more transients than the Pan-STARRS1 Medium Deep fields or the Palomar Transient Factory, with examples of transient classes that are considerably closer and brighter.
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Kamler, Jan F., and Philip S. Gipson. "Space and habitat use by resident and transient coyotes." Canadian Journal of Zoology 78, no. 12 (December 1, 2000): 2106–11. http://dx.doi.org/10.1139/z00-153.
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We radio-tracked 10 coyotes (Canis latrans) from April 1996 to March 1998 on Fort Riley Military Reservation, Kansas, to compare movements, habitat use, and survival between resident (breeders and pack associates) and transient coyotes. Home ranges of resident coyotes were mutually exclusive, whereas those of transient coyotes overlapped the home ranges of other coyotes. Excursions from home ranges were made by all resident pack associates but not by resident breeders. Grassland habitats were used more than expected by resident coyotes but less than expected by transients. Woodlands and cultivated lands were used more than expected by transients. Transient coyotes used areas between the home ranges of resident family groups. Annual survival rates were higher for resident than for transient coyotes. Avoidance of resident coyotes by transient coyotes may explain differences in space and habitat use by coyotes.
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Zhou, Xiaobo, Erxi Liu, Dezeng Sun, and Wanhua Su. "Study on transient emission spikes reduction of a heavy-duty diesel engine equipped with a variable intake valve closing timing mechanism and a two-stage turbocharger." International Journal of Engine Research 20, no. 3 (February 1, 2018): 277–91. http://dx.doi.org/10.1177/1468087417748837.
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The overall performance and emission during a speed/torque versus time transient cycle are investigated in a heavy-duty truck engine equipped with an intake valve closing timing mechanism and a two-stage turbocharger system (high-pressure turbine is variable geometry turbine). The performance discrepancy analysis between steady-state and transient operation is completed based on a fairly optimized steady-state baseline. The result shows that during the transient operation, the transient NOx emission can track the steady-state baselines much better than particle matter, and the cumulative NOx in transients is even lower than the cumulative NOx of the steady-state baselines, while the rising particle matter emissions mainly due to appearance in particle matter emission spikes during the cycle. And the transient particle matter spikes appeared almost in two typical transient conditions: sharp acceleration from idling and abrupt load transients. The instantaneous equivalence ratio (Φ) is found to be the main physical factor governing particle matter spikes formation in transients. Particle matter spikes become prominent when Φ cannot track the steady-state baseline well or Φ rises over a critical value of 0.8. The control strategy of intake valve closing timing mechanism-variable geometry turbine-exhaust gas recirculation to bridge the gap of Φ between the steady-state and the transients has been established, which effectively cut down the emission spikes, reducing particle matter emissions by 32.9% with almost no change in NOx.
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Baumann, Markus, Christian Koch, and Stephan Staudacher. "Application of Neural Networks and Transfer Learning to Turbomachinery Heat Transfer." Aerospace 9, no. 2 (January 20, 2022): 49. http://dx.doi.org/10.3390/aerospace9020049.
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Model-based predictive maintenance using high-frequency in-flight data requires digital twins that can model the dynamics of their physical twin with high precision. The models of the twins need to be fast and dynamically updatable. Machine learning offers the possibility to address these challenges in modeling the transient performance of aero engines. During transient operation, heat transferred between the engine’s structure and the annulus flow plays an important role. Diabatic performance modeling is demonstrated using non-dimensional transient heat transfer maps and transfer learning to extend turbomachinery transient modeling. The general form of such a map for a simple system similar to a pipe is reproduced by a Multilayer Perceptron neural network. It is trained using data from a finite element simulation. In a next step, the network is transferred using measurements to model the thermal transients of an aero engine. Only a limited number of parameters measured during selected transient maneuvers is needed to generate suitable non-dimensional transient heat transfer maps. With these additional steps, the extended performance model matches the engine thermal transients well.
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Ferdous, Shahriar, and Laszlo B. Kish. "Transient attacks against the Kirchhoff–Law–Johnson–Noise (KLJN) secure key exchanger." Applied Physics Letters 122, no. 14 (April 3, 2023): 143503. http://dx.doi.org/10.1063/5.0146190.
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We demonstrate the security vulnerability of an ideal Kirchhoff–Law–Johnson–Noise key exchanger against transient attacks. Transients start when Alice and Bob connect a wire to their chosen resistor at the beginning of each clock cycle. A transient attack takes place during a short duration of time, before the transients reflected from the end of Alice and Bob mix together. The information leak arises from the fact that Eve (the eavesdropper) monitors the cable and analyzes the transients during this time period. We will demonstrate such a transient attack, and then, we introduce a defense protocol to protect against the attack. Computer simulations demonstrate that after applying the defense method the information leak becomes negligible.
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Ratan, R. R., F. R. Maxfield, and M. L. Shelanski. "Long-lasting and rapid calcium changes during mitosis." Journal of Cell Biology 107, no. 3 (September 1, 1988): 993–99. http://dx.doi.org/10.1083/jcb.107.3.993.
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A more complete understanding of calcium's role in cell division requires knowledge of the timing, magnitude, and duration of changes in cytoplasmic-free calcium, [Ca2+]i, associated with specific mitotic events. To define the temporal relationship of changes in [Ca2+]i to cellular and chromosomal movements, we have measured [Ca2+]i every 6-7 s in single-dividing Pt K2 cells using fura-2 and microspectrophotometry, coupling each calcium measurement with a bright-field observation. In the 12 min before discernable chromosome some separation, 90% of metaphase cells show at least one transient of increased [Ca2+]i, 72% show their last transient within 5 min, and a peak of activity is seen at 3 min before chromosome separation. The mean [Ca2+]i of the metaphase transients is 148 +/- 31 nM (61 transients in 35 cells) with an average duration of 21 +/- 14 s. The timing of these increases makes it unlikely that these transient increases in [Ca2+]i are acting directly to trigger the start of anaphase. However, it is possible that a transient rise in calcium during late metaphase is part of a more complex progression to anaphase. In addition to these transient changes, a gradual increase in [Ca2+]i was observed starting in late anaphase. Within the 2 min surrounding cytokinesis onset, 82% of cells show a transient increase in [Ca2+]i to 171 +/- 48 nM (53 transients in 32 cells). The close temporal correlation of these changes with cleavage is consistent with a more direct role for calcium in this event, possibly by activating the contractile system. To assess the specificity of these changes to the mitotic cycle, we examined calcium changes in interphase cells. Two-thirds of interphase cells show no transient increases in calcium with a mean [Ca2+]i of 100 +/- 18 nM (n = 12). However, one-third demonstrate dramatic and repeated transient increases in [Ca2+]i. The mean peak [Ca2+]i of these transients is 389 +/- 70 nM with an average duration of 77 s. The necessity of any of these transient changes in calcium for the completion of mitotic or interphase activities remains under investigation.
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Bellan, Diego. "Analytical Investigation of the Properties of Transients in Unbalanced Three-Phase Four-Wire Networks." Energies 15, no. 23 (December 1, 2022): 9122. http://dx.doi.org/10.3390/en15239122.
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In this paper, the theoretical properties of transients in three-phase networks, including the fourth wire and unbalanced source, are systematically investigated by resorting to several analytical tools. First, a Cartesian space vector is introduced to provide the geometrical three-dimensional representation of a three-phase voltage/current transient. It is shown that a voltage/current transient can be always represented as a three-dimensional trajectory leaving one plane (corresponding to the previous steady state) towards another plane (corresponding to the new steady state at the end of the transient). The quantity driving the trajectory from one plane to another is the Park/Clarke zero component. Second, the Clarke transformation is used to study the original three-phase circuit as a superposition of two independent transients: the transient of the Clarke space vectors and the transient of the Clarke zero components. Third, the Park transformation is used to evaluate the dq0 components of transient voltages/currents. Since the Park transformation is related to the Clarke transformation through a simple frequency shift, the effects on the frequency content of the steady-state and transient waveforms are put into evidence. Three case studies are presented and solved to prove the theoretical results.
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Fourches, N. "Deep level transient spectroscopy based on conductance transients." Applied Physics Letters 58, no. 4 (January 28, 1991): 364–66. http://dx.doi.org/10.1063/1.104635.
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BRZOZOWSKI, JANUSZ, BAIYU LI, and YULI YE. "ON THE COMPLEXITY OF THE EVALUATION OF TRANSIENT EXTENSIONS OF BOOLEAN FUNCTIONS." International Journal of Foundations of Computer Science 23, no. 01 (January 2012): 21–35. http://dx.doi.org/10.1142/s0129054112400023.
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Transient algebra is a multi-valued algebra for hazard detection in gate circuits. Sequences of alternating 0's and 1's, called transients, represent signal values, and gates are modeled by extensions of boolean functions to transients. Formulas for computing the output transient of a gate from the input transients are known for NOT, AND, OR and XOR gates and their complements, but, in general, even the problem of deciding whether the length of the output transient exceeds a given bound is NP-complete. We propose a method of evaluating extensions of general boolean functions. We study a class of functions for which, instead of evaluating the extensions on a given set of transients, it is possible to get the same values by using transients derived from the given ones, but having length at most 3. We prove that all functions of three variables, as well as certain other functions, have this property, and can be efficiently evaluated.
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Lee, Karen W., Sarah E. Webb, and Andrew L. Miller. "Requirement for a localized, IP3R-generated Ca2+ transient during the furrow positioning process in zebrafish zygotes." Zygote 14, no. 2 (May 2006): 143–55. http://dx.doi.org/10.1017/s0967199406003637.
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SummaryWe report that the first localized Ca2+ transient visualized in the blastodisc cortex of post-mitotic zebrafish zygotes has unique features. We confirm that this initial ‘furrow positioning’ Ca2+ transient precedes the physical appearance of the first cleavage furrow at the blastodisc surface and that it has unique dynamics, which distinguish it from the subsequent furrow propagation transients that develop from it. This initial transient displays a distinct rising phase that peaks prior to the initiation of the two linear, subsurface, self-propagating Ca2+ waves that constitute the subsequent furrow propagation transient. Through the carefully timed introduction of the Ca2+ buffer, dibromo-BAPTA, we also demonstrate the absolute requirement of this initial rising phase Ca2+ transient in positioning the furrow at the blastodisc surface: no rising phase transient, no cleavage furrow. Likewise, the introduction of the inositol 1,4,5-trisphosphate receptor (IP3R) antagonist, 2-aminoethoxydiphenyl borate, eliminates both the rising phase transient and the appearance of the furrow at the cell surface. On the other hand, antagonists of the ryanodine receptor and NAADP-sensitive channels, or simply bathing the zygote in Ca2+-free medium, have no effect on the generation of the rising phase positioning transient or the appearance of the furrow at the surface. This suggests that like the subsequent propagation and deepening/zipping Ca2+ transients, the rising phase furrow positioning transient is also generated specifically by Ca2+ released via IP3Rs. We propose, however, that despite being generated by a similar Ca2+ release mechanism, the unique features of this initial transient suggest that it might be a distinct signal with a specific function associated with positioning the cleavage furrow at the blastodisc surface.
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Dudkowski, Dawid, Patrycja Jaros, and Tomasz Kapitaniak. "Extreme transient dynamics." Chaos: An Interdisciplinary Journal of Nonlinear Science 32, no. 12 (December 2022): 121101. http://dx.doi.org/10.1063/5.0131768.
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We study the extreme transient dynamics of four self-excited pendula coupled via the movable beam. A slight difference in the pendula lengths induces the appearance of traveling phase behavior, within which the oscillators synchronize, but the phases between the nodes change in time. We discuss various scenarios of traveling states (involving different pendula) and their properties, comparing them with classical synchronization patterns of phase-locking. The research investigates the problem of transient dynamics preceding the stabilization of the network on a final synchronous attractor, showing that the width of transient windows can become extremely long. The relation between the behavior of the system within the transient regime and its initial conditions is examined and described. Our results include both identical and non-identical pendula masses, showing that the distribution of the latter ones is related to the transients. The research performed in this paper underlines possible transient problems occurring during the analysis of the systems when the slow evolution of the dynamics can be misinterpreted as the final behavior.
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Hu, Laigui, Xian Liu, Simon Dalgleish, Michio M. Matsushita, Hirofumi Yoshikawa, and Kunio Awaga. "Organic optoelectronic interfaces with anomalous transient photocurrent." Journal of Materials Chemistry C 3, no. 20 (2015): 5122–35. http://dx.doi.org/10.1039/c5tc00414d.
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In this review, anomalous transient photocurrent from organic semiconductor devices in response to square-wave light pulses in the literature are discussed; current efforts to utilize these transients are highlighted, such as in transient-type photodetectors and artificial retinas.
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Polverino, A. J., B. P. Hughes, and G. J. Barritt. "Inhibition of Ca2+ inflow causes an abrupt cessation of growth-factor-induced repetitive free Ca2+ transients in single NIH-3T3 cells." Biochemical Journal 278, no. 3 (September 15, 1991): 849–55. http://dx.doi.org/10.1042/bj2780849.
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In single NIH-3T3 fibroblasts loaded with fura-2, bombesin induced one of three patterns of increase in the concentration of intracellular free Ca2+ [( Ca2+]i): a single transient increase, a sustained increase, or repetitive transient increases in [Ca2+]i. Foetal-calf serum and ATP also gave these three patterns of response, although a lower proportion of cells gave repetitive Ca2+ transients in response to ATP. An increase in the concentration of bombesin from 1 to 25 nM increased the proportion of cells which exhibited repetitive Ca2+ transients. At 25 nM-bombesin, the proportion of cells which exhibited repetitive Ca2+ transients increased as the extracellular Ca2+ (Ca2+o) concentration was increased from 1 to 5 mM. Removal of Ca2+o by addition of EGTA, or inhibition of Ca2+ inflow by treatment of cells incubated in the presence of Ca2+o with verapamil or an activator of protein kinase C, abruptly terminated repetitive Ca2+ transients, with only one transient observed after the cessation of Ca2+ inflow. Repetitive Ca2+ transients were not observed in cells incubated in the absence of Ca2+o and in the presence of EGTA. Addition of Ca2+o to cells previously incubated in the presence of EGTA caused a resumption of repetitive Ca2+ transients. Addition of thapsigargin alone induced a large transient increase in [Ca2+]i, whereas much smaller transient increases in [Ca2+]i were induced in about 30% of cells tested by caffeine or carbonyl cyanide m-chlorophenylhydrazone (CCCP) plus oligomycin. Thapsigargin or the combination of CCCP plus oligomycin completely inhibited bombesin-induced repetitive Ca2+ transients, whereas caffeine had no effect. It is concluded from the studies of the role of Ca2+o that NIH-3T3 cells differ from other cell types in the anatomical or chemical links between extracellular Ca2+ and the intracellular stores involved in the generation of Ca2+ transients, whereas the results of the experiments with inhibitors indicate that the generation of repetitive Ca2+ transients in NIH-3T3 cells is unlikely to involve Ca(2+)-induced Ca2+ release from caffeine-sensitive stores.
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Callewaert, G., L. Cleemann, and M. Morad. "Caffeine-induced Ca2+ release activates Ca2+ extrusion via Na+-Ca2+ exchanger in cardiac myocytes." American Journal of Physiology-Cell Physiology 257, no. 1 (July 1, 1989): C147—C152. http://dx.doi.org/10.1152/ajpcell.1989.257.1.c147.
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Rapid application of caffeine in fura-2-dialyzed and whole cell-clamped rat and guinea pig ventricular myocytes activated reversibly large intracellular Ca2+ transients that accompanied Na+-dependent transient inward currents. Such transient inward currents had the same time course as the intracellular Ca2+ transient and were suppressed by Ni2+ and removal of extracellular Na+. Because Ca2+ release signals were not altered by addition of Ni2+ or removal of Na+, we concluded that the rise in intracellular Ca2+ concentration was necessary for the activation of the transient inward current. Thus the caffeine-induced transient inward current represents efflux of Ca2+ via the Na+-Ca2+ exchanger.
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Becker, Mark W., and Sara Vera. "Attentional Filtering of Transients Allows for a Recovery from Change Blindness." Perception 36, no. 8 (August 2007): 1179–90. http://dx.doi.org/10.1068/p5750.
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Previous reports suggest that introducing distracting visual transients during a change-detection task can result in change blindness. In four experiments, we found that presenting the distracting transients repeatedly prior to the change produces a recovery from change blindness. This recovery from change blindness is not due solely to low-level neural adaptation of transient detectors, but instead seems to be based on attentional filtering of the distracting transient signals. This attentional filtering can be object-based rather than location-based. In addition, we found that the ability to achieve this attentional filtering depends critically on presenting the to-be-ignored transient signals prior to the time of the change.
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Whitfield, Paul H., and Kathleen Dohan. "Identification and characterization of water quality transients using wavelet analysis. II. Application to electronic water quality data." Water Science and Technology 36, no. 5 (September 1, 1997): 337–48. http://dx.doi.org/10.2166/wst.1997.0232.
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Two wavelet transform techniques for identifying water quality transients are applied to example data sets from two small streams. Temperature and conductance represent the range of properties from periodic processes to transient events. Both methods were successful in identifying the location, duration and magnitude of the transient events in these data sets. The methods may be refined to automate the detection and classification of transient events.
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Nuttall, L. K. "Characterizing transient noise in the LIGO detectors." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 376, no. 2120 (April 16, 2018): 20170286. http://dx.doi.org/10.1098/rsta.2017.0286.
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Data from the LIGO detectors typically contain many non-Gaussian noise transients which arise due to instrumental and environmental conditions. These non-Gaussian transients can be an issue for the modelled and unmodelled transient gravitational-wave searches, as they can mask or mimic a true signal. Data quality can change quite rapidly, making it imperative to track and find new sources of transient noise so that data are minimally contaminated. Several examples of transient noise and the tools used to track them are presented. These instances serve to highlight the diverse range of noise sources present at the LIGO detectors during their second observing run. This article is part of a discussion meeting issue ‘The promises of gravitational-wave astronomy’.
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Brotto, M. A., and T. L. Creazzo. "Ca2+ transients in embryonic chick heart: contributions from Ca2+ channels and the sarcoplasmic reticulum." American Journal of Physiology-Heart and Circulatory Physiology 270, no. 2 (February 1, 1996): H518—H525. http://dx.doi.org/10.1152/ajpheart.1996.270.2.h518.
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In the embryonic mammalian heart, virtually all the Ca2+ available for the Ca2+ transient comes through sarcolemmal Ca2+ influx. However, several studies in avian species indicate that the sarcoplasmic reticulum (SR) is functional relatively early in development. For the present report we studied fura 2 Ca2+ transients elicited by field stimulation in single isolated ventricular myocytes from the day 11 embryonic chick heart to ascertain directly the roles of the SR and Ca2+ channels. A positive staircase phenomenon was observed at higher frequencies of stimulation (1 Hz). Isoproterenol (Iso) increased the peak of the transient in a dose-dependent manner with a maximum increase of 93% in 100 microM Iso. Nifedipine (10 microM) reduced the transient such that is was not observable above background noise. However, Ca2+ transients were visible when the myocytes were stimulated by Iso. These were blocked by approximately 70% with nifedipine, suggesting that most, but not all, of the transient is associated with L-type Ca2+ current. Thus a portion of the transient may result from T-type Ca2+ channels and/or reverse Na+/Ca2+ exchange. Calculations based on integration of the Ca2+ currents and cell volume indicate that as much as one-fourth of the Ca2+ entering via sarcolemmal Ca2+ channels is from T-type channels. Ryanodine at high concentrations (10-100 microM) inhibited the transients by 30%. Both Iso and ryanodine reduced the time to peak, the time constant of the exponential decay, and the total duration of the transients. Depolarizing the myocytes with high KCl induced a large and partially sustained transient when the external solution contained 1.8 mM CaCl2. CaCl2 (10 mM) in the external solution induced large cyclic Ca2+ oscillations. These results suggest that the SR is functional in the embryonic chick heart well before hatching at day 22, although most of the Ca2+ associated with the transient comes through the sarcolemmal Ca2+ channels and possibly reverse Na+/Ca2+ exchange.
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Rehemtulla, Nabeel, Adam A. Miller, Theophile Jegou Du Laz, Michael W. Coughlin, Christoffer Fremling, Daniel A. Perley, Yu-Jing Qin, et al. "The Zwicky Transient Facility Bright Transient Survey. III. BTSbot: Automated Identification and Follow-up of Bright Transients with Deep Learning." Astrophysical Journal 972, no. 1 (August 21, 2024): 7. http://dx.doi.org/10.3847/1538-4357/ad5666.
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Abstract The Bright Transient Survey (BTS) aims to obtain a classification spectrum for all bright (m peak ≤ 18.5 mag) extragalactic transients found in the Zwicky Transient Facility (ZTF) public survey. BTS critically relies on visual inspection (“scanning”) to select targets for spectroscopic follow-up, which, while effective, has required a significant time investment over the past ∼5 yr of ZTF operations. We present BTSbot, a multimodal convolutional neural network, which provides a bright transient score to individual ZTF detections using their image data and 25 extracted features. BTSbot is able to eliminate the need for daily human scanning by automatically identifying and requesting spectroscopic follow-up observations of new bright transient candidates. BTSbot recovers all bright transients in our test split and performs on par with scanners in terms of identification speed (on average, ∼1 hr quicker than scanners). We also find that BTSbot is not significantly impacted by any data shift by comparing performance across a concealed test split and a sample of very recent BTS candidates. BTSbot has been integrated into Fritz and Kowalski, ZTF’s first-party marshal and alert broker, and now sends automatic spectroscopic follow-up requests for the new transients it identifies. Between 2023 December and 2024 May, BTSbot selected 609 sources in real time, 96% of which were real extragalactic transients. With BTSbot and other automation tools, the BTS workflow has produced the first fully automatic end-to-end discovery and classification of a transient, representing a significant reduction in the human time needed to scan.
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Timoshin, S. N., and J. M. Linkins. "Transient feedback and global instability in non-homogeneous systems." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 363, no. 1830 (April 20, 2005): 1235–45. http://dx.doi.org/10.1098/rsta.2005.1563.
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Model examples of linear wave systems are considered to illustrate the origin of feedback instability in situations involving strong transients. Two mechanisms of transient growth are addressed. The first is a spatial amplification of resonant waves propagating in the same direction. The second form of transient growth is purely temporal. It is found that under certain conditions, both forms of transients can trigger global instability in a non-homogeneous system.
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Abubakar, Ukashatu, Saad Mekhilef, Hazlie Mokhlis, Mehdi Seyedmahmoudian, Ben Horan, Alex Stojcevski, Hussain Bassi, and Muhyaddin Hosin Rawa. "Transient Faults in Wind Energy Conversion Systems: Analysis, Modelling Methodologies and Remedies." Energies 11, no. 9 (August 27, 2018): 2249. http://dx.doi.org/10.3390/en11092249.
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This paper presents an in-depth review of classical and state-of-the-art models for analysing the transient stability in wind energy conversion systems. Various transient simulation models for a number of wind turbine generator (WTG) configurations are introduced, under different disturbances. The mitigation is achieved, by manipulating the generator speed and power electronics control, whereas the protection is implemented using conventional, intelligent or digital relays for the safety of sensitive components, in case of transient fault occurrence. The various control systems in WECS are basically employed to transform and regulate the varying frequency, owing to the stochastic nature of wind speed, to the standard 50-Hz or 60-Hz frequency for coupling to an existing electrical utility grid. It has been observed that the control and protection schemes in wind energy systems are concurrently applied. Transient faults in WECSs are a dominant power quality problem especially in the doubly-fed induction generator (DFIG), and often classified as overcurrent or overvoltage transients. These transients are measured using the transient stability index and analysed using the EMTDC/PSCAD software. In addition, the inertia of the rotating masses of wind turbine generators is often characterized by a transient torque, which generates oscillations in power systems.
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Bhuvana, R. G., Abhay Singh Gour, and Parthasarathi Ghosh. "Experimental investigation of valve driven transient effect in liquid nitrogen pipeline." IOP Conference Series: Materials Science and Engineering 1240, no. 1 (May 1, 2022): 012034. http://dx.doi.org/10.1088/1757-899x/1240/1/012034.
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Abstract Liquified cryogenic fluids like Liquid oxygen, nitrogen, and hydrogen have various industrial applications. The cryogenic fluid transfer lines are generally fitted with valves to regulate, and control flow. The sudden operations of these valves lead to transient effects characterized by pressure fluctuations. The severity of pressure oscillations depends on various parameters including the valve parameters and the fluid properties. The fluid properties of cryogenic fluid in turn vary rapidly during such valve transients. In this work, a Cryogenic test facility is developed to investigate the valve-driven transients in a liquid nitrogen pipeline. The effect of the transient in the system is evaluated for two different cases of tank pressure and flow rate. The behavior of the transient is detected with the help of dynamic pressure sensors and RTD sensors. Further, the results are interpreted to understand the effect of the transient in the cryogenic fluid transfer system.
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Kostin, Alexey V. "Analysis of heating of printed circuit board conductors on a metal base for spacecraft devices at pulsed current." Physics of Wave Processes and Radio Systems 25, no. 4 (December 31, 2022): 59–66. http://dx.doi.org/10.18469/1810-3189.2022.25.4.59-66.
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The article presents the results of the analysis of heating of printed circuit conductors of printed circuit boards mounted on a metal base, on-board device of spacecraft when pulsed current flows through them. Thermal transient and impulse characteristics of a system consisting of a printed conductor and a printed circuit board are considered. The analysis of the dependence of the temperature rise rate of printed conductors and the duration of transient processes on the linear dimensions of the system elements is given. It is noted in the article that the time of transient processes most strongly depends on the thickness of the layer of insulating materials. All the results were obtained in the process of modeling transients in the ANSYS 2019 R1 Transient Thermal module. Practical recommendations on the consideration of thermal transients in printed conductors in the design of printed circuit boards are given.
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Nordin, J., V. Brinnel, J. van Santen, M. Bulla, U. Feindt, A. Franckowiak, C. Fremling, et al. "Transient processing and analysis using AMPEL: alert management, photometry, and evaluation of light curves." Astronomy & Astrophysics 631 (November 2019): A147. http://dx.doi.org/10.1051/0004-6361/201935634.
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Context. Both multi-messenger astronomy and new high-throughput wide-field surveys require flexible tools for the selection and analysis of astrophysical transients. Aims. Here we introduce the alert management, photometry, and evaluation of light curves (AMPEL) system, an analysis framework designed for high-throughput surveys and suited for streamed data. AMPEL combines the functionality of an alert broker with a generic framework capable of hosting user-contributed code; it encourages provenance and keeps track of the varying information states that a transient displays. The latter concept includes information gathered over time and data policies such as access or calibration levels. Methods. We describe a novel ongoing real-time multi-messenger analysis using AMPEL to combine IceCube neutrino data with the alert streams of the Zwicky Transient Facility (ZTF). We also reprocess the first four months of ZTF public alerts, and compare the yields of more than 200 different transient selection functions to quantify efficiencies for selecting Type Ia supernovae that were reported to the Transient Name Server (TNS). Results. We highlight three channels suitable for (1) the collection of a complete sample of extragalactic transients, (2) immediate follow-up of nearby transients, and (3) follow-up campaigns targeting young, extragalactic transients. We confirm ZTF completeness in that all TNS supernovae positioned on active CCD regions were detected. Conclusions. AMPEL can assist in filtering transients in real time, running alert reaction simulations, the reprocessing of full datasets as well as in the final scientific analysis of transient data. This is made possible by a novel way of capturing transient information through sequences of evolving states, and interfaces that allow new code to be natively applied to a full stream of alerts. This text also introduces a method by which users can design their own channels for inclusion in the AMPEL live instance that parses the ZTF stream and the real-time submission of high-quality extragalactic supernova candidates to the TNS.
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Osman, A. M., and J. V. Beck. "Investigation of Transient Heat Transfer Coefficients in Quenching Experiments." Journal of Heat Transfer 112, no. 4 (November 1, 1990): 843–48. http://dx.doi.org/10.1115/1.2910490.
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Methodological and experimental aspects of the estimation of transient heat transfer coefficients in quenching experiments, using inverse heat transfer methods, were addressed and investigated. Beck’s method was used for the estimation of the transient heat transfer coefficient history from interior transient temperature measurements during quenching. Experiments involved plunging a high-purity copper sphere into cooling baths without boiling. The sphere was instrumented with several interior thermocouples for measuring the transient temperature response during quenching. Water and ethylene glycol were investigated. The early transient values of the heat transfer coefficient history were found to be about 100–120 percent higher than the values predicted using well-known empirical correlations for free convection. The later time values were in good agreement with those predicted with empirical correlations. The transient inverse technique has the capability of estimating early transients and subsequent quasi-steady-state values of heat transfer coefficient in a single transient experiment.
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Cross, Nicholas J. G., and S. G. Djorgovski. "Optical & NIR Transient Surveys." Proceedings of the International Astronomical Union 7, S285 (September 2011): 185–90. http://dx.doi.org/10.1017/s1743921312000580.
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AbstractA workshop on Optical & Near Infrared Transients took place during the first afternoon of the Symposium. It ran for two sessions. The first was given over to talks about various current optical and near-infrared transient surveys, focussing on the Vista surveys, the Catalina Real-Time Transient Survey, Pan-STARRS, Gaia, TAOS and TAOS2. The second session was a panel-led discussion about coordinating multi-wavelength surveys and associated follow-ups.
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Qin, Yu-Jing, Ann Zabludoff, Marina Kisley, Yuantian Liu, Iair Arcavi, Kobus Barnard, Peter Behroozi, K. Decker French, Curtis McCully, and Nirav Merchant. "Linking Extragalactic Transients and Their Host Galaxy Properties: Transient Sample, Multiwavelength Host Identification, and Database Construction." Astrophysical Journal Supplement Series 259, no. 1 (February 24, 2022): 13. http://dx.doi.org/10.3847/1538-4365/ac2fa1.
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Abstract Understanding the preferences of transient types for host galaxies with certain characteristics is key to studies of transient physics and galaxy evolution, as well as to transient identification and classification in the LSST era. Here we describe a value-added database of extragalactic transients—supernovae, tidal disruption events, gamma-ray bursts, and other rare events—and their host galaxy properties. Based on reported coordinates, redshifts, and host galaxies (if known) of events, we cross-identify their host galaxies or most likely host candidates in various value-added or survey catalogs, and compile the existing photometric, spectroscopic, and derived physical properties of the host galaxies in these catalogs. This new database covers photometric measurements from the far-ultraviolet to mid-infrared. Spectroscopic measurements and derived physical properties are also available for a smaller subset of hosts. For our 36,333 unique events, we have cross-identified 13,753 host galaxies using host names, plus 4480 using host coordinates. Besides those with known hosts, there are 18,100 transients with newly identified host candidates. This large database will allow explorations of the connections of transients to their hosts, including a path toward transient alert filtering and probabilistic classification based on host properties.
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Probst, Felipe L., Michael Beltle, and Stefan Tenbohlen. "Measurement of Transient Overvoltages by Capacitive Electric Field Sensors." Sensors 24, no. 5 (February 20, 2024): 1357. http://dx.doi.org/10.3390/s24051357.
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The accurate measurement and the investigation of electromagnetic transients are becoming more important, especially with the increasing integration of renewable energy sources into the power grid. These sources introduce new transient phenomena due to the extensive use of power electronics. To achieve this, the measurement devices must have a broadband response capable of measuring fast transients. This paper presents a capacitive electric field sensor-based measurement system to measure transient overvoltages in high-voltage substations. The concept and design of the measurement system are first presented. Then, the design and concept are validated using tests performed in a high-voltage laboratory. Afterwards, two different calibration techniques are discussed: the simplified method (SM) and the coupling capacitance compensation (CCC) method. Finally, three recorded transients are evaluated using the calibration methods. The investigation revealed that the SM tends to overestimate the maximum overvoltage, highlighting the CCC method as a more suitable approach for calibrating transient overvoltage measurements. This measurement system has been validated using various measurements and can be an efficient and flexible solution for the long-term monitoring of transient overvoltages in high-voltage substations.
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Anderson, G. E. "Discovering Radio Transients using ‘Triggered’ and ‘Targeted’ Observations." Proceedings of the International Astronomical Union 14, S339 (November 2017): 39–42. http://dx.doi.org/10.1017/s174392131800217x.
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AbstractAs the era of the Square Kilometre Array approaches, astronomers are investigating how to make good use of its facilities for studying radio transients. This talk presented two different methods for radio transient discovery – ‘triggered’ and ‘targeted’ observations – which can be used to supplement the blind survey approach. Both techniques focus on performing radio observations of sky regions in which we expect to find radio transients. ‘Triggered’ observations are obtained by telescopes capable of responding rapidly to transient alerts; they automatically repoint and begin collecting data within minutes of the alert being given. ‘Targeted’ observational techniques involve radio monitoring of specific sources or regions such as nearby, face-on galaxies, globular clusters, and the Galactic Plane. Such observations are sensitive to transient radio jets from black holes accreting at, or above, the Eddington limit, with the additional benefit of providing many potential sources within a single field of view. Both observing strategies illustrate important techniques for radio transient discovery that can be employed by the SKA.
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AA, Gareev. "Environmental Issues of Transient Behavior." Petroleum & Petrochemical Engineering Journal 5, no. 4 (2021): 1–10. http://dx.doi.org/10.23880/ppej-16000284.
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We are currently witnessing a high-rate of exploitation of oil fields at the stage of declining production. This decline is a result of the depletion of oil fields, which leads to the use of electric submersible centrifugal pumps (ESP) with dynamic head below saturation pressure. In this operating mode, the ESP’s efficiency deteriorates, leading to the overheating of its working elements during operation. The boiling of water contained in the wellstream and salt deposition can take place in an overheated pump. This, in turn, can lead to a premature failure of the centrifugal pump and reduce the economic viability of this oil production method. To eliminate premature failure, such units must be transferred to an operating mode with periodic shutdowns. Yet, the planning of trip-out and restart time schedules is performed in the absence of a proper theoretical justification. Such planning often leads to ESP failures due to the reduction of the electric resistance of cable lines or salt deposition. To prevent salt deposition, oil production companies use different chemicals, which are pumped into the hole annulus and are expected to stop salt deposition when propelled into the pump pot. Chemical treatment practice shows that these reagents perform poorly and may not prevent salt deposition at all. In reality, chemical compounds can damage downhole equipment and its structural elements. Long-term use of these reagents may lead to ecological disaster – the contamination of productive formations and confined groundwater beds. This work investigates the possibility of ESP operation in periodic mode without salt deposition and the exploitation of oil fields without the application of chemical reagents. The development of a periodic operation method allowing for ESP operation without salt deposition could eliminate the use of reagents in oil production and thereby reduce the risk of ecological disasters.
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Pandey, Manas, Debasis Mishra, and Sajid Nomani. "Post Traumatic Transient Cortical Blindness." Indian Journal of Emergency Medicine 4, no. 2 (June 15, 2018): 162–63. http://dx.doi.org/10.21088/ijem.2395.311x.4218.18.
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Transient cortical blindness is a rare complication of mild head trauma, but it always creates fear in the patient and their family. However, it usually has a benign outcome. Post traumatic Transient Cortical Blindness is defined as temporary and complete visual loss associated with normal pupillary reflexes and fundoscopic examination with return of visual function without any long term neurological complications following minor head trauma. Since the number of reported cases are very less, transient blindness after head injury has been mostly attributed to hysteria if brain imaging and fundoscopy examination is normal. Post traumatic Transient Cortical Blindness was first reported by Lemiere [in 1918]but its pathophysiology is still unknown. We report one such case of transient blindness.
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Saulitis, Eva L., Craig O. Matkin, and Francis H. Fay. "Vocal repertoire and acoustic behavior of the isolated AT1 killer whale subpopulation in southern Alaska." Canadian Journal of Zoology 83, no. 8 (August 1, 2005): 1015–29. http://dx.doi.org/10.1139/z05-089.
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Killer whales, Orcinus orca (L., 1758), in the North Pacific are classified as three genetically distinct ecotypes: residents (fish-eaters), transients (mammal-eaters), and offshores (probable fish-eaters). Within the transient ecotype, three putative subpopulations have been identified by genetic analysis: West Coast transients, Gulf of Alaska transients, and AT1 transients. Here, we examine the behavior and vocalizations of the AT1 transients, which are found only in the Prince William Sound/Kenai Fjords region, to determine if their acoustic behavior distinguishes them from other genetically distinct transient subpopulations. We identified 14 discrete, pulsed calls in the vocal repertoire of the AT1 transients. These calls were entirely different than those of West Coast and sympatric Gulf of Alaska transients. Despite their large call repertoire, AT1 transients were silent most of the time, utilizing a foraging strategy of stealth, acoustic crypsis, and passive listening for locating marine-mammal prey. Unlike resident killer whales, AT1 transient vocalization types were context specific. For example, lone AT1 transients produced long-distance, high-amplitude pulsed calls in stereotyped sequences to locate other AT1 whales. In contrast, hunting individuals emitted low-amplitude pulsed calls to maintain contact with group members. The repertoire and call-usage patterns of the AT1 transients are consistent with genetic evidence that they are a unique, reproductively and socially isolated subpopulation in danger of extinction.
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Durden, Stephen L., Victor A. Vilnrotter, and Scott J. Shaffer. "Assessment of Techniques for Detection of Transient Radio-Frequency Interference (RFI) Signals: A Case Study of a Transient in Radar Test Data." Eng 4, no. 3 (August 21, 2023): 2191–203. http://dx.doi.org/10.3390/eng4030126.
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The authors present a case study of the investigation of a transient signal that appeared in the testing of a radar receiver. The characteristics of the test conditions and data are first discussed. The authors then proceed to outline the methods for detecting and analyzing transients in the data. For this, they consider several methods based on modern signal processing and evaluate their utility. The initial method used for identifying transients is based on computer vision techniques, specifically, thresholding spectrograms into binary images, morphological processing, and object boundary extraction. The authors also consider deep learning methods and methods related to optimal statistical detection. For the latter approach, since the transient in this case was chirp-like, the method of maximum likelihood is used to estimate its parameters. Each approach is evaluated, followed by a discussion of how the results could be extended to analysis and detection of other types of transient radio-frequency interference (RFI). The authors find that computer vision, deep learning, and statistical detection methods are all useful. However, each is best used at different stages of the investigation when a transient appears in data. Computer vision is particularly useful when little is known about the transient, while traditional statistically optimal detection can be quite accurate once the structure of the transient is known and its parameters estimated.
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Anderson, G. E., B. W. Stappers, I. Andreoni, M. Caleb, D. Coppejans, S. Corbel, R. P. Fender, et al. "Radio Transients in the Era of Multi-Messenger Astrophysics." Proceedings of the International Astronomical Union 14, S339 (November 2017): 207–14. http://dx.doi.org/10.1017/s1743921318002624.
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AbstractRadio emission from astrophysical transients allows us to derive calorimetry of kinetic feedback and detailed imaging in ways that are not possible at other wavelengths, and as such it forms an important part of the multi-messenger follow-ups of these events. The field is burgeoning, with a renaissance of interest in accretion, stellar explosions and jetted supernovæ, alongside newer classes of phenomena such as fast radio bursts and tidal disruption events. The purpose of this workshop was to discuss the infrastructure and techniques for detecting, identifying and probing radio transients, with a particular focus on how best to exploit transient alerts from multi-messenger facilities. We examined the type of transient alerts those facilities will broadcast, and methods for following them up, such as rapid-response triggering and shadowing. In break-out groups, participants chose a science question related to a particular radio transient type or class and discussed whether the planned transient strategies and observing techniques on the Square Kilometre Array will be adequate to address the particular question. The classes they chose included fast radio bursts, supernovæ, cataclysmic variable and unknown transients. Any proposed adaptation or suggestion was relayed to a panel of experts for further discussion. The second part of the workshop concentrated on the application of long baseline interferometry for detecting and measuring radio transients.
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Wang, Jun, and R. Natarajan. "Microcomputer Aided Transient Analysis." International Journal of Electrical Engineering & Education 29, no. 1 (January 1992): 61–70. http://dx.doi.org/10.1177/002072099202900107.
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Microcomputer-aided transient analysis In this paper a mathematical model based on differential equations and state variables is used to describe the transients in an electric circuit. The numerical and graphical solution is obtained by using Runge-Kutta method and implemented on a microcomputer using a spreadsheet program.
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Hartmann, T., M. Kondo, H. Mochizuki, A. S. Verkman, and J. H. Widdicombe. "Calcium-dependent regulation of Cl secretion in tracheal epithelium." American Journal of Physiology-Lung Cellular and Molecular Physiology 262, no. 2 (February 1, 1992): L163—L168. http://dx.doi.org/10.1152/ajplung.1992.262.2.l163.
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In primary cultures of dog tracheal epithelium, isoproterenol produced a transient increase in short-circuit current (Isc) (duration 30 s; maximal increase, 32 +/- 5 microA/cm2). This was followed by a more slowly developing sustained increase (9 +/- 3 microA/cm2), which mimicked the response to N6, 2'-O-dibutyryladenosine 3',5'-cyclic monophosphate (DBcAMP). The transient and sustained responses had dissociation constants for isoproterenol of 2 x 10(-8) and 2 x 10(-9) M, respectively. Bradykinin (in the presence of indomethacin), substance P, histamine, and thrombin produced only transient increases in Isc. The time courses of these transients closely paralleled changes in concentration of intracellular Ca ([Ca2+]i) as measured with fura 2. For different mediators, there was a significant correlation between the maximal transient increase in Isc and the maximal increase in [Ca2+]i. The transients in Isc were not associated with elevation of adenosine 3',5'-cyclic monophosphate (cAMP) and were unaffected by pretreatment with DBcAMP, which abolishes the steady-state increase in response to isoproterenol. Both the transient increases in Isc and [Ca2+]i were inhibited by pretreatment with the Ca chelator 1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid. The phorbol ester 12-O-tetradecanoylphorbol 13-acetate abolished the transient increases in [Ca2+]i and Isc in response to isoproterenol but not to bradykinin. These results provide evidence that 1) isoproterenol and bradykinin elevate [Ca2+]i by different mechanisms, and 2) Ca elevation is associated with a transient increase in Isc, whereas increased cAMP is associated with a smaller sustained increase.
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Fan, Wei, Z. K. Zhu, Wei Guo Huang, and Gai Gai Cai. "Sparse Representation De-Noising Based on Morlet Wavelet Basis and its Application for Transient Feature Extraction." Applied Mechanics and Materials 526 (February 2014): 200–204. http://dx.doi.org/10.4028/www.scientific.net/amm.526.200.
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Signals with multiple transients are often encountered with much noise in engineering. The transient feature extraction has always been the key issue for signal analysis. A new signal de-noising method combining sparse representation and Morlet wavelet basis is proposed for signal de-noising and feature extraction. Simulation study concerning multiple transients signal shows the effectiveness of this method in transient feature extraction. The efficiency of this de-noising method is also verified by its application to extract fault signature for gearbox.
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Vinkó, József, Benjamin P. Thomas, J. Craig Wheeler, Anna Y. Q. Ho, Erin Mentuch Cooper, Karl Gebhardt, Robin Ciardullo, et al. "Searching for Supernovae in HETDEX Data Release 3*." Astrophysical Journal 946, no. 1 (March 1, 2023): 31. http://dx.doi.org/10.3847/1538-4357/acbfa8.
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Abstract We have extracted 636 spectra taken at the positions of 583 transient sources from the third data release of the Hobby–Eberly Telescope Dark Energy eXperiment (HETDEX). The transients were discovered by the Zwicky Transient Facility (ZTF) during 2018–2022. The HETDEX spectra provide a potential means to obtain classifications for a large number of objects found by photometric surveys for free. We attempt to explore and classify the spectra by utilizing several template-matching techniques. We have identified two transient sources, ZTF20aatpoos = AT 2020fiz and ZTF19abdkelq, as supernova (SN) candidates. We classify AT 2020fiz as a Type IIP SN observed ∼10 days after explosion, and we propose ZTF19abdkelq as a likely Type Ia SN caught ∼40 days after maximum light. ZTF photometry of these two sources are consistent with their classifications as SNe. Beside these two objects, we have confirmed several ZTF transients as variable active galactic nuclei based on their spectral appearance, and determined the host galaxy types of several other ZTF transients.