Sudden Changes In Intensity Research Articles

Analysis of characteristics and evaluation of forecast accuracy for Super Typhoon Doksuri (2023)

Super Typhoon Doksuri is a significant meteorological challenge for China this year due to its strong intensity and wide influence range, as well as significant and prolonged hazards. In this work, we studied Doksuri's main characteristics and assessed its forecast accuracy meticulously based on official forecasts, global models and regional models with lead times varying from 1 to 5 days. The results indicate that Typhoon Doksuri underwent rapid intensification and made landfall at 09:55 BJT on July 28 with a powerful intensity of 50 m s−1 confirmed by the real-time operational warnings issued by China Meteorological Administration (CMA). The typhoon also caused significant wind and rainfall impacts, with precipitation at several stations reaching historical extremes, ranking eighth in terms of total rainfall impact during the event. The evaluation of forecast accuracy for Doksuri suggests that Shanghai Multi-model Ensemble Method (SSTC) and Fengwu Model are the most effective for short-term track forecasts. Meanwhile, the forecasts from the European Centre for Medium-Range Weather Forecasts (ECMWF) and United Kingdom Meteorological Office (UKMO) are optimal for long-term predictions. It is worth noting that objective forecasts systematically underestimate the typhoon maximum intensity. The objective forecast is terribly poor when there is a sudden change in intensity. CMA-National Digital Forecast System (CMA-NDFS) provides a better reference value for typhoon accumulated rainfall forecasts, and regional models perform well in forecasting extreme rainfall. The analyses above assist forecasters in pinpointing challenges within typhoon predictions and gaining a comprehensive insight into the performance of each model. This improves the effective application of model products.

An Intuitionistic Fuzzy C-Means and Local Information-Based DCT Filtering for Fast Brain MRI Segmentation.

Structural and photometric anomalies in the brain magnetic resonance images (MRIs) affect the segmentation performance. Moreover, a sudden change in intensity between two boundaries of the brain tissues makes it prone to data uncertainty, resulting in the misclassification of the pixels lying near the cluster boundaries. The discrete cosine transform (DCT) domain-based filtering is an effective way to deal with structural and photometric anomalies, while the intuitionistic fuzzy C-means (IFCM) clustering can handle the uncertainty using the intuitionistic fuzzy set (IFS) theory. In this background, we propose two novel approaches, namely, the DCT-based intuitionistic fuzzy C-means (DCT-IFCM) and the DCT-based local information IFCM (DCT-LIFCM), which effectively deal with the Rician and Gaussian noises and also handle the data uncertainty problem to provide high segmentation accuracy. The DCT-IFCM approach performs the histogram-based segmentation, while the DCT-LIFCM uses the pixel-wise computation to include the spatial information. Although the DCT-LIFCM delivers slightly better performance than the DCT-IFCM, the latter is very fast in providing equally high segmentation accuracy. An exhaustive performance analysis is provided to demonstrate the superior performance of the proposed algorithms compared with the state-of-the-art algorithms, including those based on the DCT-based filtering approach and the IFS theory.

Comparison of Tiling Artifact Removal Methods in Secondary Ion Mass Spectrometry Images.

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) imaging is used across many fields for the atomic and molecular characterization of surfaces, with both high sensitivity and high spatial resolution. When large analysis areas are required, standard ToF-SIMS instruments allow for the acquisition of adjoining tiles, which are acquired by rastering the primary ion beam. For such large area scans, tiling artifacts are a ubiquitous challenge, manifesting as intensity gradients across each tile and/or sudden changes in intensity between tiles. Such artifacts are thought to be related to a combination of sample charging, local detector sensitivity issues, and misalignment of the primary ion gun, among other instrumental factors. In this work, we investigated six different computational tiling artifact removal methods: tensor decomposition, multiplicative linear correction, linear discriminant analysis, seamless stitching, simple averaging, and simple interpolating. To ensure robustness in the study, we applied these methods to three hyperspectral ToF-SIMS data sets and one OrbiTrapSIMS data set. Our study includes a carefully designed statistical analysis and a quantitative survey that subjectively assessed the quality of the various methods employed. Our results demonstrate that while certain methods are useful and preferred more often, no one particular approach can be considered universally acceptable and that the effectiveness of the artifact removal method is strongly dependent on the particulars of the data set analyzed. As examples, the multiplicative linear correction and seamless stitching methods tended to score more highly on the subjective survey; however, for some data sets, this led to the introduction of new artifacts. In contrast, simple averaging and interpolation methods scored subjectively poorly on the biological data set, but more highly on the microarray data sets. We discuss and explore these findings in depth and present general recommendations given our findings to conclude the work.

Wavelength-Dependent Optical Response of Single Photosynthetic Antenna Complexes from Siphonous Green Alga Codium fragile.

The siphonaxanthin-siphonein-Chl-a/b-protein (SCP) complex from the siphonous green alga Codium fragile is the major light-harvesting complex (LHC) of these alga and is highly homologous to that of green plants (trimeric pigment-protein complex, LHCII). Interestingly, we find remarkable differences in the spectral response from individual SCP complexes when excited at 561 and 639 nm. While excitation in the green spectral range reproduces the common LHCII-like emission features for most of the complexes, excitation in the red spectral range yields a red-shifted emission and a significant reduction of the fluorescence decay time. We hypothesize that the difference in spectral response of SCP to light in the green and red spectral ranges can be associated with the adaption of the algae to their natural habitat under water, where sudden intensity changes are diminished, and excess light features a red-enhanced spectrum that comes at tidal timings.

Understanding the characteristics of rapid intensity changes of Tropical Cyclones over North Indian Ocean

North Indian Ocean (NIO), which comprises of Bay of Bengal (BoB) and Arabian Sea (AS) basins, is one of the highly potential regions for Tropical Cyclones (TCs) in the world. Significant improvements have been achieved in the prediction of the movement of TCs, since the last decade. However, the prediction of sudden intensity changes becomes a challenging task for the research and operational meteorologists. Hence, the present study focuses on finding the climatological characteristics of such intensity changes over NIO regions. Rapid Intensification (RI) is defined as the 24-h maximum sustained surface wind speed rate equal to 30 knots (15.4 ms−1). The results suggest that the TCs formed over the NIO basin are both seasonal and basin sensitive. Since 2000, a significant trend is observed in RI TCs over the basin. At least one among three cyclones getting intensified is of RI category. More number of RI cases have been identified in the BoB basin than the AS. The post-monsoon season holds more RI and rapid decay cases, with 63% and 90% contribution. Most of the TCs are attaining RI onset in their initial stage. Further, India is receiving more landfalling RI TCs, followed by Bangladesh and Oman. The east coast of India, Tamil Nadu, and Andhra Pradesh are the most vulnerable states to these RI TCs. The cyclogenesis locations associated with RI cases hold higher moisture, and sea surface temperature as compared to the Non-RI cases.

Topographic Rainfall of Tropical Cyclones past a Mountain Range as Categorized by Idealized Simulations

Abstract Topographic rainfall induced by westbound tropical cyclones past an island mountain is investigated using an idealized Weather Research and Forecasting (WRF) Model. Idealized simulations with varying vortex core size R (100–250 km), vortex intensity Vmax (20–35 m s−1), and steering wind speed U (4–10 m s−1) are conducted. The results show that the geometric distributions of major rainfall over the island are not greatly sensitive to cloud microphysics schemes using either single momentum or double momentum. Major rainfall is produced over northeastern and southwestern slopes of the mountain for smaller U. As U is doubled, the rainfall, however, is considerably weakened or is present only over southwestern slopes. For smaller U, a bifurcation of island rainfall with a sudden change in intensity or geometric shifting exists within a tiny range of R or Vmax. When the bifurcation occurs with small track deviations, geometric distributions of major rainfall are also more sensitive to cloud microphysics schemes. Such formation of bifurcation or double-peak rainfall, however, is significantly reduced when the terrain size is doubled. Systematic experiments are conducted to relate the topographical rainfalls over the northern half, southern half, and the whole of the mountain slopes to varying R, Vmax, and U. Larger U tends to produce much larger southern rainfall than northern rainfall. The average and maximum rainfalls generally increase with increased Vmax, except for large R. The decrease of average rainfall and maximum rainfall with increased U is more evident for smaller R, while not necessarily true for larger R.

Accurate ball tracking in volleyball actions to support referees

This paper proposes a method for offline accurate ball tracking for short volleyball actions in sport halls. Our aim is to detect block touches on the ball and to determinate accurate trajectory and impact positions of the ball to support referees. The proposed method is divided into two stages, namely training and ball tracking, and is based on background subtraction. Application of the Gaussian mixture model has been used to estimate a background, and a high-speed camera with a capture rate of 180 frames per second and a resolution of 1920 × 1080 are used for motion capture. In sport halls significant differences in light intensity occur between each sequence frame. To minimize the influence of these light changes, an additional model is created and template matching is used for accurate determination of ball positions when the ball contour in the foreground image is distorted. We show that this algorithm is more accurate than other methods used in similar systems. Our light intensity change model eliminates almost all pixels added to images of moving objects owing to sudden changes in intensity. The average accuracy achieved in the validation process is of 0.57 pixel. Our algorithm accurately determined 99.8% of all ball positions from 2000 test frames, with 25.4 ms being the average time for a single frame analysis. The algorithm presented in this paper is the first stage of referee support using a system of many cameras and 3D trajectories.

Voltage-induced Infrared Absorption from a Spin-cast Thin Film of Ferroelectric Poly(vinvlidene fhioride-co-trifluoroethvlene) (P(VDF-TrFE))

Voltage-induced infrared spectra of annealed spin-cast thin films of ferroelectric poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) (molar ratio, 3:1) were measured in a stepwise cyclic external electric field. Most of the observed infrared bands originated from the β ferroelectric crystalline phase. The voltage-induced spectral changes were decomposed into zeroth- (original), first-, and second-derivative spectra, and were attributed to the rotational motions of the polymer chains and the vibrational Stark effect. The values of the original spectral absorbance change ratios, ΔA/A, for the 849-cm-1 band (CF2 symmetric stretching, a1) and the 884-cm-1 band (CH2 rocking, b2) of the film exhibited double minimum and maximum peak hysteresis loops, respectively. The intensity of each band increased or decreased suddenly near a coercive field of ±0.6 MV/cm. These sudden intensity changes were attributed to the rotational inversion of the polymer chains that are associated with ferroelectricity.

Monte Carlo simulations for the analysis of texture and strain measured with Bragg edge neutron transmission

The transmission spectrum of cold and thermal neutrons displays sudden intensity changes, known as Bragg edges, whose appearance is connected to the crystallographic structure of the investigated sample. However, many difficulties in interpreting and understanding the detected signal exist, in particular when results are evaluated quantitatively. We measured strain and texture properties of different samples utilizing the Bragg edge method on the CONRAD and VSANS instruments at Helmholtz Centre Berlin as well as on ENGIN-X at ISIS, UK. The different results will be compared and validated with conventional diffraction measurements and theoretical considerations. According to this, a Bragg edge neutron transmission simulation was developed to include instrument effects together with sample characteristics. Therefore, a neutron ray-tracing simulation package was applied to emulate the employed instruments in combination with the Bragg edge transmission technique. A new sample module has been created to realize energy-dependent transmission simulations based on neutron cross sections calculations. Towards the analysis of the conducted experiments the virtual sample features the expected strain and texture parameters. The results of the simulation are in good agreement with the experiments and will be discussed with regard to the prospects and limitations of this measurement method and the utilized instruments.

Forbush decreases – clouds relation in the neutron monitor era

The proposed influence of cosmic rays on cloud formation is tested for the effect of sudden intensity changes of CR (Forbush decreases) on cloudiness. An attempt is made to widen the investigated period covered by satellite observation of cloudiness. As an indicator of cloud cover, the diurnal temperature range (DTR - a quantity anticorre- lated with cloudiness) is used. The superposed epoch anal- ysis on a set of isolated Forbush decreases is conducted and the results for a region of Europe are presented. The effect of Forbush decrease on DTR is statistically significant only if the analysis is restricted to high amplitude FDs (above the threshold value of 7% with the respect to undisturbed CR in- tensity). The magnitude of the effect on DTR is estimated to be (0.38± 0.06) C.

Applicability of White-Noise Techniques to Analyzing Motion Responses

Motion processing in visual neurons is often understood in terms of how they integrate light stimuli in space and time. These integrative properties, known as the spatiotemporal receptive fields (STRFs), are sometimes obtained using white-noise techniques where a continuous random contrast sequence is delivered to each spatial location within the cell's field of view. In contrast, motion stimuli such as moving bars are usually presented intermittently. Here we compare the STRF prediction of a neuron's response to a moving bar with the measured response in second-order interneurons (L-neurons) of dragonfly ocelli (simple eyes). These low-latency neurons transmit sudden changes in intensity and motion information to mediate flight and gaze stabilization reflexes. A white-noise analysis is made of the responses of L-neurons to random bar stimuli delivered either every frame (densely) or intermittently (sparsely) with a temporal sequence matched to the bar motion stimulus. Linear STRFs estimated using the sparse stimulus were significantly better at predicting the responses to moving bars than the STRFs estimated using a traditional dense white-noise stimulus, even when second-order nonlinear terms were added. Our results strongly suggest that visual adaptation significantly modifies the linear STRF properties of L-neurons in dragonfly ocelli during dense white-noise stimulation. We discuss the ability to predict the responses of visual neurons to arbitrary stimuli based on white-noise analysis. We also discuss the likely functional advantages that adaptive receptive field structures provide for stabilizing attitude during hover and forward flight in dragonflies.

Stability of the crystal structure of L‐valine under high pressure

AbstractRaman scattering measurements were carried out on a single crystal of L‐valine with the pressure increasing from the ambient value to 6.9 GPa. Sudden changes in intensity of the bands were observed in the higher energy spectral range at ∼3 GPa and ∼5.3 GPa. Discontinuities observed in the wave number vs. pressure plots occurred in the complete spectrum at those same pressures, suggesting changes in the crystal structure. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

COMMENTS

owell and Reinhold’s (2007) summary and brief discussion of several proposed scale designs as suitable alternatives to the Saffir–Simpson (SS) scale, defining damage potentials in hurricanes, is a useful contribution. Our comment here, however, pertains specifically to the new scale they propose based upon the integration of kinetic energy. While there are a number of procedural questions about the proposed new scale that merit discussion, this comment is primarily concerned with how well their scale may serve operational needs during hurricane crises, not only in warning decisions, but as a tool of communication with both public and private interests. The proposed scale may prove useful in postanalyses of hurricane wind distributions in relating integrated kinetic energy values to the character and scope of wind damage; however, it is unlikely to relate usefully to the processes that created the existing intensity to begin with, much less the significant changes that often defy prediction. Kinetic energy may relate well to analyses of wind loading on various structures, and possibly to a better identification—if not understanding—of more subtle processes generated from purely dynamic sources. However, the development of hurricane intensity and, more importantly, abrupt changes of intensity, depend significantly on the forcing from thermodynamic as well as dynamic sources. This is not only a critical prediction problem, but one of communicating the consequences of changes to both the public and private interests. Kinetic energy itself is arguably the least conservative property of any severe storm, exhibiting large variations from point to point, both in space and time, especially in urban coastal areas. The computation of kinetic energy from immediately available observational sources and its spatial integration is time consuming (according to the above-mentioned paper, there is a time lag of 6 hours), yielding numerical results that must be adjusted using arbitrarily derived coefficients of questionable validity when applied universally. These considerations raise serious questions about the applicability of such a scale to the time-sensitive operational requirements of hurricane warnings and evacuations, especially when the new scale does not take into account the thermodynamic contribution to sudden intensity changes that this forcing may invoke. The SS scale, since its introduction more than three decades ago, has been numerically related in each of its categories to hurricane central pressure, whose values are functionally related to both thermodynamic and dynamic sources of forcing. As such, it is a conservative index for both the stability and any eminent changes of intensity. It is readily measurable from reconnaissance aircraft by dropsonde and with close approximation from satellite observations, which is an asset that any attempt to improve the present scale should incorporate. It was the intended policy and practice at the time the SS scale was introduced by the National Hurricane Center to relate operationally the assignment of categories primarily in terms of net releases of energy as reflected in either changes or steadiness of central pressure values, remaining wary of individual point values of the highly variable, often ephemeral, reported maximum wind speeds. This proved particularly useful in assessing the transitions from tropical storm stages to hurricane strength. Of course, there are significant fluctuations in central pressure values too. However, in our view and experience these changes tend to usefully reflect the net competing sources of energy releases, for example, vertical shear

Analysis of ‘blinking’ or ‘hopping’ single molecule signals with a limited number of transitions

Most single molecule fluorescence signals exhibit two characteristic features: sudden intensity changes (‘blinking’, ‘hopping’) and a limited length (‘bleaching’). I show that the correlation functions of such ‘truncated telegraph signals’ for Poisson processes contain linear segments and oscillatory features, deviating strongly from the expected exponential decay. I find that the slope of the initial linear section of the normalized signal autocorrelation is a robust and reliable statistical estimate for the rate of sudden intensity changes in single molecule fluorescence signals with 4 to 100 transitions per trace, significantly outperforming an exponential fit.

The uhleri group of the genus Amblycorypha (Orthoptera: Tettigoniidae): extraordinarily complex songs and new species

The uhleri group of the genus Amblycorypha consists of A. uhleri Stål and 4 new species: arenicola, cajuni, longinicta, and rivograndis. The species are easily distinguished in the field by features of their songs, and most specimens can be identified by size and features of the ovipositor and male stridulatory apparatus. Males of the uhleri group produce the most complex calls known for ensiferan Orthoptera and thus earn the common name of “virtuoso katydids”. Each species uses 4 types of wing-movement cycles to produce 4 types of syllable sequences. During these sequences there are gradual and sudden changes in intensity. The 4 types of sequences are produced in more or less predictable order, with a complete song requiring 4 to > 60 s depending on the species, the population, and the temperature. In response to these songs, sexually responsive females make nondescript answering “ticks” immediately before and during the place in the songs where the males produce “type IV” syllables. Available evidence suggests that sequences of type I and II syllables are of special significance in eliciting ticks from females, that type III sequences may function in causing females to approach the male from afar, and that type IV sequences may lessen the chances of cuckoldry by eavesdropping males.

Theory of First Layer and Single Molecule Surface Enhanced Raman Scattering (SERS)

The first layer SERS effect is usually ascribed to dynamical charge transfer (DCT) between metal and absorbate, following a model by Persson. Experiments show that there is no first layer SERS effect at smooth noble metal surfaces, in spite of the surface resistance caused by adsorbates, which is also caused by DCT according to Persson. On the other hand, both SERS and SEIRA (surface enhanced infrared absorption) of ethylene on cold-deposited Cu display at low coverages exactly the same Raman active modes, which can be only understood by DCT. The apparent difference is attributed to special events of double scattering by DCT and atomic scale surface roughness, which prevent dephasing of the optical currents in the electromagnetic resonances. The double scattering model explains the observed change of the SERS background and SERS phonon spectra during annealing of the atomic scale roughness. Single molecule SERS is assigned to molecules within narrow and small contact zones of metal particle. The vibrations are effectively excited by the optical currents flowing through the molecule, without becoming dephased. “Blinking” (sudden changes in intensity and band positions) is assigned to thermally activated atomic scale jumps of the molecule, frozen out at low temperatures in agreement with experimental observations.

Helium atom scattering from the Si(111) surface at high temperatures

Helium atom scattering has been used to investigate the structure of the Si(111) surface in the temperature range from 900 to 1600 K. Even below the well-known (7{times}7) to {open_quotes}(1{times}1){close_quotes} transition the adatoms become mobile, and, when the transition is reached near 1140 K, the specular- and integral-order diffraction peaks have sudden intensity changes, some up and others down, while the seventh-order peaks disappear. Above the transition the adatoms remain, moving rapidly on, and supported by, the ordered but relaxed, outer bilayer of the surface. A second transition, first reported by Ishizaka and co-workers occurs near 1470 K. The loss of all diffraction peaks and the attenuation of the specular peak indicate a completely disordered surface as the temperature approaches the melting point. {copyright} {ital 1997} {ital The American Physical Society}

Control of a Rotary Pulsatile Cardiac Assist Pump Driven by an Electric Motor Without a Pressure Sensor to Avoid Collapse of the Pump Inlet

Our ventricular assist device uses a valveless volumetric pump operating on the Maillard-Wankel rotary principle. It is driven by an electric motor and provides a semi pulsatile flow. At each cycle, blood is actively aspirated into the device, and overpumping results in collapse at the pump inlet. To prevent overpumping, it is necessary to ensure that pump intake does not exceed venous return. Poor long-term reliability rules out the use of current implantable pressure sensors for this purpose. To resolve this problem, we have developed a method of control based on monitoring of the intensity of electric current consumed by the motor. The method consists of real time monitoring of current intensity at the beginning of each pump cycle. A sudden change in intensity indicates underfilling, and motor speed is reduced to prevent collapse. The current consumed by the motor also depends on the afterload, but the form of the signal remains the same when afterload changes. After demonstrating the feasibility of this technique in a simulator, we are now testing it in animals. We were able to detect and prevent collapse due to overpumping by the cardiac assist device. This system also enables us to know the maximum possible assistance and to thus adapt assistance to the user.

The daily cercarial emission rhythm of Schistosoma margrebowiei with particular reference to dark period stimuli

The cercariae of Schistosoma margrebowiei showed two peaks of emergence from Bulinus natalensis in a 12 h light/dark cycle. Peak emission occurred at 0700 h (one hour after the onset of light) and at 1900 h (one hour after the onset of darkness). Both peaks were of equal magnitude and were maintained during constant illumination indicating that the rhythm is innate. Delaying or advancing the timing of the dark period did not affect the timing of these two peaks. Following a five minute dark treatment elevation in cercarial output resulted irrespective of when the treatment was applied. Subjecting snails to various intensities of light only resulted in an elevation in output when a sudden change in intensity from 0 to 360 Lux or the reverse was applied. No response was seen to a gradual change in light intensity although the parasite could detect a change in light from 1 to 0 Lux. These responses appear to optimize the chances of host parasite contact.

Effects of interplanetary shocks on kilometric type III radio bursts

Interplanetary (IP) type III bursts that undergo sudden intensity changes when their electron beams traverse the vicinity of an IP shock are examined. Three types of intensity changes are discussed: cutoffs in which the type III intensity is abruptly reduced and remains at the reduced level for all lower frequencies, narrow‐band intensifications that frequently occur on the high‐frequency edge of a cutoff, and narrow‐band intensity reductions. Pitch angle scattering of the beam electrons in the enhanced magnetic turbulence downstream of shocks is proposed as a principal cause of the intensity cutoffs and, possibly, the intensifications. These observations suggest that one type III emission mode (fP or 2fP) is frequently at least 10 times more intense than the other mode.