Significant Changes In Amplitude Research Articles

Entropy Could Quantify Brain Activation Induced by Mechanical Impedance-Restrained Active Arm Motion: A Functional NIRS Study.

Brain activation has been used to understand brain-level events associated with cognitive tasks or physical tasks. As a quantitative measure for brain activation, we propose entropy in place of signal amplitude and beta value, which are widely used, but sometimes criticized for their limitations and shortcomings as such measures. To investigate the relevance of our proposition, we provided 22 subjects with physical stimuli through elbow extension-flexion motions by using our exoskeleton robot, measured brain activation in terms of entropy, signal amplitude, and beta value; and compared entropy with the other two. The results show that entropy is superior, in that its change appeared in limited, well established, motor areas, while signal amplitude and beta value changes appeared in a widespread fashion, contradicting the modularity theory. Entropy can predict increase in brain activation with task duration, while the other two cannot. When stimuli shifted from the rest state to the task state, entropy exhibited a similar increase as the other two did. Although entropy showed only a part of the phenomenon induced by task strength, it showed superiority by showing a decrease in brain activation that the other two did not show. Moreover, entropy was capable of identifying the physiologically important location.

Effects of Transcranial Direct Current Stimulation on Attentional Bias to Methamphetamine Cues and Its Association With EEG-Derived Functional Brain Network Topology.

Although transcranial direct current stimulation (tDCS) has shown to potentially mitigate drug craving and attentional bias to drug-related stimuli, individual differences in such modulatory effects of tDCS are less understood. In this study, we aimed to investigate a source of the inter-subject variability in the tDCS effects that can be useful for tDCS-based treatments of individuals with methamphetamine (MA) use disorder (IMUD). Forty-two IMUD (all male) were randomly assigned to receive a single-session of either sham or real bilateral tDCS (anodal right/cathodal left) over the dorsolateral prefrontal cortex. The tDCS effect on MA craving and biased attention to drug stimuli were investigated by quantifying EEG-derived P3 (a measure of initial attentional bias) and late positive potential (LPP; a measure of sustained motivated attention) elicited by these stimuli. To assess the association of changes in P3 and LPP with brain connectivity network (BCN) topology, the correlation between topology metrics, specifically those related to the efficiency of information processing, and the tDCS effect was investigated. The P3 amplitude significantly decreased following the tDCS session, whereas the amplitudes increased in the sham group. The changes in P3 amplitudes were significantly correlated with communication efficiency measured by BCN topology metrics (r = -0.47, P = .03; r = -0.49, P = .02). There was no significant change in LPP amplitude due to the tDCS application. These findings validate that tDCS mitigates initial attentional bias, but not the sustained motivated attention, to MA stimuli. Importantly, however, results also show that the individual differences in the effects of tDCS may be underpinned by communication efficiency of the BCN topology, and therefore, these BCN topology metrics may have the potential to robustly predict the effectiveness of tDCS-based interventions on MA craving and attentional bias to MA stimuli among IMUD.

Effects of angiotensin peptides on colonic motility in rats.

Renin-angiotensin system (RAS) is involved in the pathophysiology of colonic inflammation. The aim of this study was to investigate whether small angiotensins (Angs) peptides play a role in the regulation of colonic motility and their roles are modulated in colitis. Experimental colitis was induced by an intake of 5% dextran sulfate sodium (DSS) dissolved in tap water for 7 days in Sprague-Dawley rats. After sacrifice, plasma hormone concentrations and messenger RNAs (mRNAs) for RAS were measured. Functional analysis of colonic motility in response to Angs peptides was performed using Taenia coli. DSS-treated colon showed an increased necrosis with massive infiltration of inflammatory cells. The mRNA level of colonic angiotensin II receptor type 2 (AT2R) in DSS-treated rats was higher than that in control rats whereas the mRNA levels of angiotensin II converting enzyme (ACE), ACE2, AT1R, AT4R, and Mars receptor were not different from those in control rats. Ang III, Ang IV, and Ang-(1-9) (1, 3 μM) increased the frequency of basal colonic motility. Ang-(1-7) did not cause any significant changes in frequency and amplitude of basal motility. The order of potency for an increased frequency of basal motility seems to be Ang II>>Ang IV>Ang III=Ang-(1-9). The increased frequency of basal motility by Ang-(1-9) but not Ang IV was significantly enhanced in DSS-treated rat colon. In conclusion, these data suggest that small Angs peptides are partly involved in the pathophysiological regulation of colonic motility in experimental colitis.

Ecological inference using data from accelerometers needs careful protocols.

Accelerometers in animal‐attached tags are powerful tools in behavioural ecology, they can be used to determine behaviour and provide proxies for movement‐based energy expenditure. Researchers are collecting and archiving data across systems, seasons and device types. However, using data repositories to draw ecological inference requires a good understanding of the error introduced according to sensor type and position on the study animal and protocols for error assessment and minimisation.Using laboratory trials, we examine the absolute accuracy of tri‐axial accelerometers and determine how inaccuracies impact measurements of dynamic body acceleration (DBA), a proxy for energy expenditure, in human participants. We then examine how tag type and placement affect the acceleration signal in birds, using pigeons Columba livia flying in a wind tunnel, with tags mounted simultaneously in two positions, and back‐ and tail‐mounted tags deployed on wild kittiwakes Rissa tridactyla. Finally, we present a case study where two generations of tag were deployed using different attachment procedures on red‐tailed tropicbirds Phaethon rubricauda foraging in different seasons.Bench tests showed that individual acceleration axes required a two‐level correction to eliminate measurement error. This resulted in DBA differences of up to 5% between calibrated and uncalibrated tags for humans walking at a range of speeds. Device position was associated with greater variation in DBA, with upper and lower back‐mounted tags varying by 9% in pigeons, and tail‐ and back‐mounted tags varying by 13% in kittiwakes. The tropicbird study highlighted the difficulties of attributing changes in signal amplitude to a single factor when confounding influences tend to covary, as DBA varied by 25% between seasons.Accelerometer accuracy, tag placement and attachment critically affect the signal amplitude and thereby the ability of the system to detect biologically meaningful phenomena. We propose a simple method to calibrate accelerometers that can be executed under field conditions. This should be used prior to deployments and archived with resulting data. We also suggest a way that researchers can assess accuracy in previously collected data, and caution that variable tag placement and attachment can increase sensor noise and even generate trends that have no biological meaning.

Noise Reduction in Electrical Signal Using OMP Algorithm Based on DCT and DSC Dictionaries

The noise is the most common issue present in all signals. Depending on the process or application, the reduction of the noise is mandatory mainly in areas such as signal classification, pattern recognition, and training process, among others. In recent years, diverse methodologies for noise reduction have been proposed, but they have left some issues with no solution. Such are the noise reduction in signals immersed in white noise without changes in their amplitude or phase or the high performance of recovering components of the desire signals distributed among the frequency spectrum. Also, filtering techniques without significant changes in signal phase and amplitude are necessary. This article proposes a methodology for noise reduction based on the orthogonal matching pursuit algorithm with dictionaries constructed from kernel functions of the discrete cosine transform and discrete sine transform. The methodology is proved in synthetic signals and real electrical signals, reaching noise reduction of white noise (~34 dB in electrical signals) and recovering without distortion.

Nanocollision mediated electrochemical sensing of host-guest chemistry at a nanoelectrode surface.

Electrochemical (EC) measurements of dynamic nanoparticle collisions on a support electrode provide a powerful approach to study the electrical properties of interfacial molecules self-assembled on the electrode surface. By introducing a special cage-shaped macrocyclic molecule, cucurbit[7]uril (CB7), onto a gold nanoelectrode surface, we show that the dynamic interactions between CB7 and the colliding nanoparticles can be real-time monitored via the appearance of distinct EC current switching signals. When a guest molecule is included in the CB7 cavity, the changed host-guest chemistry can be probed via the amplitude change of the EC current signals. In addition, different guest molecules can be recognized by CB7 on the nanoelectrode surface, giving rise to distinguishable current jump signals for different host-guest systems. Remarkably, two well-defined current states are observed in the EC measurements of the CB7-ferrocene complex, indicating two orientation geometries of ferrocene inside the CB7 cavity can be resolved in this EC sensing platform. This work demonstrates an effective approach for studying the dynamics of host-guest chemistry at the liquid-solid interface and sheds light on a convenient EC sensor for the recognition of target molecules with the aid of CB7.

Design of a New 3D Chaotic System Producing Infinitely Many Coexisting Attractors and Its Application to Weak Signal Detection

This paper proposes a new 3D chaotic system, which can produce infinitely many coexisting attractors. By introducing a boosted control of cosine function to an original chaotic system, as the initial conditions periodically change, the proposed chaotic system can spontaneously output infinitely many chaotic sequences of different amplitudes in two directions in the phase plane. This means that the proposed system can output more key information as a pseudo-random signal generator (PRSG). This is of great significance in the research of weak signal detection. In comparison with the original chaotic system, the chaotic behavior of the proposed system is obviously enhanced due to the introduction of the boosted control function. Then, by adding the mathematical models of a weak signal and a noise signal to the proposed chaotic system, a new chaotic oscillator, which is sensitive to the weak signal, can be restructured. With the change of weak signal amplitude and angular frequency, the dynamical state of the detection system will generate a big difference, which indicates that the weak signal can be detected successfully. Finally, the proposed chaotic system model is physically realized by DSP (Digital Signal Processing), which shows its feasibility in industrial implementation. Especially, since a third-order chaotic system is the lowest-dimensional continuous system that can generate infinitely many coexisting attractors, the proposed chaotic system is of great value in the basic research of chaos.

Reconfigurable Mach-Zehnder interferometer for dynamic modulations of spoof surface plasmon polaritons.

We propose an ultrathin reconfigurable Mach-Zehnder interferometer (MZI) for realizing dynamic frequency and amplitude modulations of spoof surface plasmon (SSP) signal. Active varactor diodes are integrated in the SSP unit cells on one of the MZI arms to introduce asymmetry to the MZI structure, which can control the interference patterns by varying bias voltages applied on the varactor diodes. We show that the spectral positions of multiple sharp interference dips are very sensitive to the change of diode capacitance, thereby allowing for good frequency modulation. We also demonstrate continuous amplitude modulation by tuning the varactor diodes at multiple selected frequencies. To verify the reconfigurable feature of the proposed SSP MZI, the frequency shift keying (FSK) and amplitude modulations have been experimentally demonstrated on the same structure. The modulation depth of the amplitude modulation can be further improved by designing geometrical parameters of the SSP structure, reaching a significant amplitude change from 0.88 to 0.05 in experiments.

Influence of Magnetostriction Induced by the Periodic Permanent Magnet Electromagnetic Acoustic Transducer (PPM EMAT) on Steel.

The periodic permanent magnet electromagnetic acoustic transducer (PPM EMAT) is a sensor that can generate and receive shear horizontal (SH) waves without direct contact with the inspected medium using the Lorentz mechanism. However, the PPM EMAT experiences high signal variance on ferromagnetic steel under specific conditions, such as a change in signal amplitude when the sensor is moved in the direction of SH wave propagation. Magnetostriction effects are hypothesized to be the cause of these anomalous behaviors; the objective of this paper is to determine the relative strengths of the magnetostriction and Lorentz wave generation mechanisms for this type of EMAT on steel. This goal is accomplished through the use of a second EMAT, which induces only magnetostriction (MS-EMAT), to calibrate a novel semi-empirical magnetostriction model. It is found that magnetostriction effects reduce the amplitude of the SH wave generated by this particular PPM EMAT transmitter by an average of 29% over a range of input currents. It is also determined that magnetostriction is significant only in the investigated PPM EMAT transmitter, not the receiver. In terms of practical application, it is shown that the MS-EMAT is less sensitive to changes in the static and dynamic fields than PPM EMATs at specific operating points; this makes the MS-EMAT a viable alternative for nondestructive evaluation despite lower amplitudes.

Adaptation of dolphins’ (Tursiops truncatus) location signals when searching for and identifying objects hidden by sea sediments

ABSTRACT An experimental study was conducted to research dolphins’ sonar adaptation capabilities for location of objects obscured by marine sediments. It was shown that dolphins are able to alter spectral and temporal characteristics of their location signals. Adaptive change in length, spectral width and amplitude of signals provides optimal tools to fight interference and allows dolphins to effectively identify objects.

Seasonal Changes in Climate Variables in Rainfed Crop Areas in the Lerma-Chapala-Santiago Basin, Mexico

This paper shows the effects of changes in the spatial-temporal behavior and phase shift of climate variables on rainfed agriculture in the Lerma-Chapala-Santiago Basin in central Mexico. Specifically, changes in rainfall (R), maximum temperature (Tmax), and minimum temperature (Tmin) were analyzed over two 25-year periods (1960 to 1985 and 1986 to 2010). Climate surfaces were generated by interpolation using the thin-plate smoothing spline algorithm in the software ANUSPLIN. Climate data were Fourier-transformed and fitted to a sinusoidal curve model, and changes in amplitude (increase) and phase were analyzed. The temporal behavior (1960–2010) indicated that rainfall was the most stable variable at the monthly level and presented no significant changes. However, Tmax increased by 2°C in the final period, and Tmin increased by 0.7°C at the end of the final period. The basin was discretized into ten rainfed crop areas (RCAs) according to the extent of changes in the amplitude and phase of the climate variables. The central and southern portions (55% of the area) presented more significant changes in amplitude, mainly in Tmin and Tmax. The remaining RCAs were smaller (14.6%) but presented greater variation: the amplitude of the Tmin decreased in addition to showing a phase shift, whereas Tmax increased in addition to showing a phase shift. These results translate into a delay in the characteristic temperatures of the spring and summer seasons, which can impact the rainfed crop cycle. Additionally, rainfall showed an annual decrease of approximately 50 mm in all RCAs, which can affect the phenological development of crops during critical stages (emergence through flowering). These changes represent a significant threat to the regional economy and food security of Mexico.

Seasonal trends in the Southeast Florida current and shelf CO2 fluxes

An anthropogenically driven increase in atmospheric CO2 concentrations is known to drive an increase in the globally integrated ocean carbon sink. However, there is significant regional and seasonal variability, and significant changes in seasonal cycle amplitudes have been predicted. Three decades of sea surface observations collected from the southeast Florida Current and shelf waters reveal behavior over seasonal and interannual timescales for a region important to global carbon storage and transport. The strong temperature dependence of fCO2 in the region dominates the seasonal cycle of air-sea flux, although biophysical processes are also important. The possibility of wet and dry seasonal asymmetric trends through time were evaluated, but no statistically significant trends were found. The results indicate that uptake in the region has not changed over the last three decades after accounting for sampling bias and demonstrate the importance of robust seasonally unbiased data sets in conducting climate studies. Even in this highly sampled region, data distribution biases were found, mainly in the early 1990s. Seasonally biased data are thus not only a problem for polar regions but can also affect flux calculations in sub-tropical regions. Although not statistically significant to date, different responses in different seasons with time may lead to seasonal amplification and a decoupling of the annual mean and the seasonal means in the future.

Direct-write piezoelectric coating transducers in combination with discrete ceramic transducer and laser pulse excitation for ultrasonic impact damage detection on composite plates

In this work, direct-write piezoelectric transducers (DWTs) were made by spraying piezoelectric poly(vinylidene fluoride-co-trifluoroethylene) coating with comb-shaped electrodes on carbon fibre reinforced polymer (CFRP) plates for drop weight impact damage detection. Their ability and performance were investigated and compared to discrete piezoelectric lead zirconate titanate (PZT) ceramic transducers that were adhesively bonded on the same CFRP plate. Guided wave signals were acquired with different combinations of actuator-sensor involving DWT, PZT and laser ultrasonic excitation, in pitch-catch configuration. DWTs allowed consistency and simplified signal interpretation due to an effective mode selection (A0 or S0 mode) with wavelengths of 10 and 12 mm. PZTs generated stronger but much more complex signals and mode selection with a larger wavelength (20 mm). The configuration with PZT as actuator and DWT as receiver showed the highest signal amplitude changes of A0 or S0 mode, allowing efficient detection of damage introduced by a 31 J impact. Further ultrasonic B- and C-scans revealed a 27 mm long crack on the plate’s backside developed in addition to internal cracks and delaminations of about 34 mm in length. For realizing contactless ultrasound excitation, a neodymium-doped yttrium aluminium garnet laser (wavelength of 1064 nm, 5.4 ns pulses) was used to replace the surface-mounted brittle PZT. The combination of the broadband laser excitation with the DWTs as sensors achieved more reliable damage detection than equivalent PZTs, attributed to DWT’s effective single mode selection. In addition to reduced weight, the polymeric coated DWTs allow large area implementation (scaling up), even on curved surfaces due to their flexibility and conformability, in contrast to adhesively bonded discrete transducers.

Is 0.01% Atropine an Effective and Safe Treatment for Myopic Children? A Systemic Review and Meta-Analysis.

Several conflicting results regarding the efficacy of 0.01% atropine in slowing axial elongation remain in doubt. To solve this issue and evaluate the safety of 0.01% atropine, we conducted a systematic review and meta-analysis with the latest evidence. The review included a total of 1178 participants (myopic children). The efficacy outcomes were the mean annual progression in standardized equivalent refraction (SER) and axial length (AL). The safety outcomes included mean annual change in accommodative amplitude, photopic and mesopic pupil diameter. The results demonstrated that 0.01% atropine significantly retarded SER progression compared with the controls (weighted mean difference [WMD], 0.28 diopter (D) per year; 95% confidence interval (CI) = 0.17, 0.38; p < 0.01), and axial elongation (WMD, −0.06 mm; 95% CI = −0.09, −0.03; p < 0.01) during the 1-year period. Patients receiving 0.01% atropine showed no significant changes in accommodative amplitude (WMD, −0.45 D; 95% CI = −1.80, 0.90; p = 0.51) but showed dilated photopic pupil diameter (WMD, 0.35 mm; 95% CI = 0.02, 0.68; p = 0.04) and mesopic pupil diameter (WMD, 0.20 mm; 95% CI = 0.08, 0.32; p < 0.01). In the subgroup analysis of SER progression, myopic children with lower baseline refraction (>−3 D) and older age (>10-year-old) obtained better responses with 0.01% atropine treatment. Furthermore, the European and multi-ethnicity groups showed greater effect than the Asian groups. In conclusion, 0.01% atropine had favorable efficacy and adequate safety for childhood myopia over a 1-year period.

Features of the performance of cognitive auditory evoked potentials by adolescents with intellectual disabilities

The article informs about the results of theoretical and practical study the features of the implementation of cognitive load by adolescents with intellectual disabilities. The involvement of the cerebrospinal system and, in particular, the brain, in the performance of the cognitive load was determined using the standardized P300 method of evoked potentials, traditionally used to detect cognitive impairments and assess the brain function in children with problems of behavior, attention, and learning. As a result of the experiment, it was shown that with normative cognitive load - the allocation of significant stimulus - at the group of adolescents with normal intellectual development, a statistically significant change in wave amplitude and latency was observed Р3 wave. At the group of adolescents with intellectual disabilities these results were not revealed. Recommendations. The authors have developed pedagogical methods of working with adolescents with intellectual disabilities.

Establishment of novel standardised operating procedures for LF‐NMR: used in rapid detection of typical fruit and vegetable

SummaryAlthough LF‐NMR has been widely used in many fields of food science, the lack of NMR expertise of many food researchers needs to be bridged. Using samples of carrots, bananas, and king oyster mushroom, this work systematically studied the influence of LF‐NMR parameters (repetition time (TR), echo time (TE)) on experimental results. The result showed that the TR of carrot, mushroom and banana were 2684, 4572 and 4317 ms, respectively. The rate of change of signal amplitude can be used as an index to optimise TR. The change of TE has different effects on the short relaxation components of the T2 distributions and long relaxation components in different TR samples. TE and Nech should be set according to T2 to record completely the decay process. What’s more, the method of normalised CPMG decay was suggested to eliminate the effects of parameters such as number of scan (NS), pre‐amp regulate gain (PRG) and mass of sample. At last, the standardised operating procedures were proposed to provide a strategy of improving the properties and applications of LF‐NMR.

Dry Needling For The Treatment Of Spasticity In Persons With Multiple Sclerosis

Spasticity is a symptom commonly reported by person’s with multiple sclerosis (PwMS) which can make walking difficult thus increasing energy expenditure and exacerbating symptoms of fatigue. It has been proposed that dry needling, a common practice in orthopedics and sports medicine for treating pain, may decrease spasticity in PwMS. PURPOSE: To determine whether repeated sessions of dry needling with electrical stimulation followed by walking with functional electrical stimulation to the gastroc and tib anterior in PwMS resulted in a decreased level of spasticity as measured by the number of foot-taps and mean muscle EMG amplitude. METHODS: Sixteen PwMS (10 females and 6 males, mean age: 47.9 ± 10.0) were recruited and completed 4 separate sessions of dry needling of the gastrocnemius followed by functional electrical stimulation walking (FESW). Subjects went on to complete 8 more sessions with FESW only. Pre and post needling gastrocnemius EMG mean amplitude was assessed during a 5-second heel raise. EMG was furthermore assessed pre and post FESW. The number of foot-taps was assessed using the foot-tapping test (FTT). Results were compared using repeated measures ANOVA and paired samples t-tests. Of the original 16, only 11 subjects had a complete EMG dataset capable of being analyzed. RESULTS: No significant changes were seen in the mean EMG amplitude between pre and post needling tests in either the first (Pre: 43.4 ± 23.5 μV, Post: 41.2 ± 21.1 μV, p = 0.47) or last needling sessions (Pre: 50.8 ± 32.0 μV, Post: 50.5 ± 24.0 μV, p = 0.93) nor was the post needling EMG different between the first and last needling sessions (p = 0.18). Furthermore, no significant differences in amplitude were found post FESAW at any of the dry needling sessions or FESAW only sessions (all p > 0.05). Despite a non-significant difference in EMG amplitude, there was a significant increase in foot-taps from the first visit (24.1 ± 7.9 foot-taps) to the final visit (27.6 ± 6.5 foot-taps, p < 0.01). CONCLUSION: Neither dry needling nor FESAW sessions resulted any significant changes in mean EMG amplitude of the gastrocnemius during heel raises. Despite this, there was a significant increase in mean foot tapping ability between pre and post intervention which may lend some support to the efficacy of dry needling for the improvement of spasticity in PwMS.

Piezoelectric-sensored sustainable pads for smart railway traffic and track state monitoring: Full-scale laboratory tests

The present paper focuses on an initial assessment into the applicability of sensored sustainable pads, made from recycled polymers and embedded with commonly-accessible piezoelectrics. These sensing devices were used as smart rail pads and inside bituminous sub-ballast to monitor traffic and track state by measuring the stress variations in the components. A series of full-scale laboratory tests were carried out simulating train passage under diverse traffic scenarios and varying track section conditions in a testing box. Results indicated that the smart sustainable pads in both components showed the capacity to detect traffic load variations by measuring relative changes in signal amplitude of the sensor. Nonetheless, the smart rail pads presented higher accuracy to monitor axle loads, while the signals from the sub-ballast were influenced by the position of the sensor and so a higher potential to monitor track performance, rail-sleeper load distribution and detecting phenomena like hanging sleepers.

Error characteristic analysis of fiber optic current transformer with sine modulation

The optoelectronic circuit and modulation circuit of the fiber optic current transformer (FOCT) are easily affected by the complex environment in the converter station during operation, leading to abnormal operation and fault warning. In order to analyze the error characteristic on the output signal and harmonics of FOCT, the output signal models of FOCT with sine modulation in steady-state and error-state are established respectively in this paper. Combined with the output signal, the key parameters are solved, and it is pointed out that the change of photoelectric circuit may cause the ratio error. The Faraday phase shift and the change of the modulation circuit may cause the drift error. The error characteristics of the FOCT under different influencing factors are simulated and analyzed. The results show that output signal of FOCT is influenced by photoelectric circuit, Faraday phase shift circuit and modulation circuit. Changes in the photoelectric circuit will cause a proportional change in the FOCT output signal and harmonics. Both the Faraday phase-shifting and the increasing of modulation amplitude will reduce the minimum value of output signal. Changes in Faraday phase shift will cause an approximately proportional change in first harmonic. Changes in modulation signal amplitude will cause the harmonics to appear attenuate and oscillate. The modulation frequency is inversely proportional to the period of the output signal and harmonics. Both the first and second harmonics can be used as the monitoring state parameters of fault determination. Designed experiment verified the correctness of the conjecture. This article provides a theoretical basis for the follow-up status monitoring and fault diagnosis of FOCT.

Mechanism study for directivity of TR probe when applying Eddy current testing to ferro-magnetic structural materials

Transmitter/receiver (TR) pancake probes are widely used in eddy current testing (ECT) owing to their multi-axial structure and sensitivity in different directions. However, the behavior of the ECT signal affected by the directivity of the TR pancake probe has not been discussed, especially when considering the magnetic properties of materials. The present paper therefore investigates the behavior of the ECT signal for different angles between the crack orientation and the centerline of the probe in experiments and numerical analysis. In experiments, sample plates of ferromagnetic carbon steel SM490 and non-ferromagnetic stainless steel AISI316 are employed for the investigation. Slits are fabricated on the plates to simulate cracks. Numerical analysis adapts a finite element method, the Ar method. The change in signal amplitude with the scanning angle has an obvious difference between the two materials in both experimental and simulation results. The presence of magnetic flux leakage around a slit in ferromagnetic material is assumed as the main reason for the difference and subsequently examined in numerical analysis. The results reveal that the magnetic field detected for a ferromagnetic material is the superposition of the magnetic field induced by eddy current and the magnetic flux leakage. The present study confirms the presence of magnetic flux leakage and explains the difference in the directivity of a TR pancake probe between ferromagnetic and non-ferromagnetic materials. This work contributes to a more reasonable analysis of ECT signals measured using a TR pancake probe when detecting cracks in different materials and the evaluation of crack orientation.