Absolute Parameter Research Articles

Measurement Technique for the Absolute Acoustic Nonlinearity Parameter Employing Only a Narrowband Pulser

In the nonlinear ultrasonic technique, the measurement of the absolute acoustic nonlinearity parameter is employed to obtain quantitative material nonlinearity. In the piezoelectric method, this measurement involves two processes: calibration and harmonic measurements. In the calibration process, a transfer function is obtained, and distortion of the propagating wave is measured in the harmonic measurement. In the conventional method for this measurement, a narrowband pulser is typically used for the harmonic measurement, while a broadband pulser is used for the calibration measurement. In this study, we propose a technique that utilizes a narrowband pulser for both harmonic and calibration measurements. First, we introduced the proposed method to measure the transfer function in the calibration measurement employing the narrowband pulser. Then, we compared the results of the transfer functions and the absolute acoustic nonlinearity parameters obtained using both a narrowband and broadband pulser in the calibration. Based on the experimental results, we found that the results obtained using both the proposed and conventional methods are highly similar, confirming the validity of the proposed measurement technique. In conclusion, even though we exclusively employ the narrowband pulser, we can accurately measure the absolute nonlinearity parameter, leading to a reduction in the required measurement equipment.

Damage evolution and acoustic emission characteristics of sandstone under different true triaxial cyclic loading and unloading modes

In the process of deep coal mining, the cyclic mining disturbance behavior produces significant cyclic loading and unloading effects, to ensure safe production in the mining area, it is necessary to study the damage characteristics and acoustic emission characteristics of the rock body under different cyclic loading and unloading effects. This study developed a TAWZ-5000/3000 rock true triaxial (disturbance) test system and used it to carry out true triaxial cyclic loading and unloading tests in different modes, with acoustic emission (AE) monitoring of the deformation and damage processes. The test results proved that a large number of cycles weakens the rock’s ability to control deformation, and this weakening ability is also related to the types of cyclic loading and unloading modes. The hysteresis loop characteristics and mechanical parameters show obvious path dependence. Based on the damage equivalence method, it is found that the absolute damage parameter increases with the increase of the number of cycles in the same mode, and the accumulation rate of the cumulative damage parameter is faster; the cumulative damage parameter in the equal amplitude cyclic loading and unloading (EAC) mode is always higher than that in the other two modes. The normalized AE ring count rate in the rock samples under cyclic loading and unloading has a significant relationship with the damage percentage, and the crack extension scale function (b-value) shows the “steady increase – strong fluctuation − significant decline” trend. By analyzing the AE characteristic parameters, namely rise time/amplitude (RA) and ringing count/duration (AF), it is found that the sandstones in EAC, graded cyclic loading and unloading (GC), and stepped cyclic loading and unloading (SC) modes are mainly damaged by tension-shear and shear, respectively. By analyzing the values of the acoustic emission parameters RA-AF, it is found that the sandstone is mainly damaged by tensile shear, tensile tension, and shear under EAC, GC, and SC modes, respectively, corresponding to the rock samples’ damage patterns. The study results have important guiding significance for preventing and controlling disasters in deep mines.

The YMDB catalog: Young massive detached binaries for the determination of high-precision absolute stellar parameters

Context. Massive stars play a crucial role in the cosmic dynamics and chemical evolution of galaxies. Despite their significance, our understanding of their evolution and properties remains limited. An accurate determination of stellar parameters, such as the mass and radius, is essential for advancing our knowledge. Detached eclipsing binaries (DEBs) are particularly valuable for these determinations due to the minimal interaction between their stellar components, allowing for precise measurements. Aims. This study aims to introduce the Young Massive Detached Binary (YMDB) catalog, designed to address the gap in the high-precision absolute parameter determination for young massive stars. By focusing on DEBs within the spectral range O9-B1, this catalog seeks to provide a reliable database for future astronomical studies and improve our understanding of massive star evolution. Methods. We conducted a photometric analysis of 87 young massive stars in detached eclipsing systems using TESS light curves (LCs) that were processed through a custom pipeline. This analysis involved determining the amplitude of magnitude variations, orbital periods, times of minima, eccentricities, and the presence of apsidal motion and heartbeat phenomena. A thorough literature review was performed to obtain MK spectral classifications. We performed our own spectral classification of 19 systems to support the sample where a new classification was lacking or inconclusive. Results. The analysis identified 20 previously unreported binary systems, with 13 newly recognized as variable stars. Among the 87 stars examined, 30 are confirmed as YMDB members, and 25 are candidates pending spectral classification. The exclusion of the remaining 32 stars is attributed to unsuitable spectral types or their nondetached binary nature. Notable findings include the identification of new LC classifications, eccentricities in 13 systems, and heartbeat phenomena in several targets. Conclusions. The YMDB catalog offers a resource of high-quality LCs and reliable stellar classifications, serving as a valuable tool for the astronomical community.

Agreement and Consistency of Absolute and Relative Corticospinal Stimulus-Response Curves for Upper, Lower, and Axial Musculature in Healthy Adults.

To assess the agreement and consistency of absolute and relative stimulus-response curve (SRC) parameter estimates for upper extremity, lower extremity, and axial muscles. Thirty (15 W, age: 27.0 ± 6.3 y, height: 171.9 ± 8.9 cm, weight: 80.2 ± 19.3 kg) healthy adults completed absolute (5% to 100% stimulator output) and relative (65% to 160% motor threshold) SRCs of the first dorsal interosseous, vastus lateralis, and rectus abdominis during submaximal isometric contractions. Mean motor-evoked potential amplitudes were fit with nonlinear regression to derive MEPmax, V50, and slope. Absolute agreement and consistency were assessed with ICCs, Cronbachs alphas, and Bland-Altman plots. Independent t-tests were used to examine differences in motor threshold, physical activity, strength, and muscle activity among participants with valid and invalid SRC parameters. Absolute and relative SRCs displayed good agreement and consistency for MEPmax and V50 but not slope. Motor thresholds were lower among participants with valid absolute SRCs for the rectus abdominis and vastus lateralis. Motor threshold, physical activity, strength, and muscle activity did not differ among those with valid and invalid parameters for all relative SRCs and absolute SRCs for the first dorsal interosseous. Absolute and relative SRCs produce similar MEPmax and V50 estimates in the first dorsal interosseous, vastus lateralis, and rectus abdominis. The validity of absolute and relative SRC results may differ depending on individual characteristics and tested muscles.

Determination of the absolute nonlinear parameters using a pulse-echo method in a terminal impedance-mismatched system

ABSTRACT The pulse-echo method is desirable in practice because it enables single-sided measurement of the absolute nonlinear parameter (β), allowing quantitative characterisation of material properties, such as early damage and elastic constants. Transducer calibration is an essential step to determine the absolute β. However, the current transducer calibration method requires dedicated systems or specific apparatuses for the pulse-echo setup. Impedance-mismatch configurations involving different types of apparatuses have been employed in various studies, but there has not been work investigating and solving the effects of terminal impedance on the determination of β. In this study, the theory of the terminal impedance effect on the transfer function, as well as the β measurements is derived. A practical calibration method is proposed to eliminate the influence of the impedance-mismatched problem and the restrictions of specific apparatuses or experimental configurations. Three simple and impedance-mismatched experimental configurations were designed with general apparatuses. Nonlinear experiments were performed to determine the β of water using planar and focused transducers in the pulse-echo systems with these configurations. The measured β agrees with the reference value, which verifies the effectiveness of the proposed correction method. The measured results using the three configurations are also discussed to give practical advice for building a nonlinear pulse-echo setup.

Optimization and validation of the DESIGNER preprocessing pipeline for clinical diffusion MRI in white matter aging

Abstract Various diffusion MRI (dMRI) preprocessing pipelines are currently available to yield more accurate diffusion parameters. Here, we evaluated accuracy and robustness of the optimized Diffusion parameter EStImation with Gibbs and NoisE Removal (DESIGNER) pipeline in a large clinical dMRI dataset and using ground-truth phantoms. DESIGNER, a preprocessing pipeline targeting various imaging artifacts in diffusion MRI data, has been modified to improve denoising and target Gibbs ringing for partial Fourier acquisitions. We compared the revised DESIGNER (Dv2) (including denoising, Gibbs removal, correction for motion, echo planar imaging (EPI) distortion, and eddy currents) against the original DESIGNER (Dv1) pipeline, minimal preprocessing (including correction for motion, EPI distortion, and eddy currents only), and no preprocessing on a large clinical dMRI dataset of 524 control subjects with ages between 25 and 75 years old. We evaluated the effect of specific processing steps on age correlations in white matter with diffusion tensor imaging (DTI) and diffusion kurtosis imaging (DKI) metrics. We also evaluated the added effect of minimal Gaussian smoothing to deal with noise and to reduce outliers in parameter maps compared to DESIGNER-v2’s noise removal method. Moreover, Dv2’s updated noise and Gibbs removal methods were assessed using a ground truth dMRI phantom to evaluate accuracy. Results show age correlations of DTI and DKI metrics in white matter were affected by the preprocessing pipeline, causing systematic differences in absolute parameter values and loss or gain of statistical significance. Both in clinical dMRI and ground-truth phantoms, Dv2 pipeline resulted in the smallest number of outlier voxels and improved accuracy in DTI and DKI metrics as noise was reduced and Gibbs removal was improved. Thus, DESIGNER-v2 provides more accurate and robust DTI and DKI parameter maps by targeting common artifacts present in dMRI data acquired in clinical settings, as compared to no preprocessing or minimal preprocessing.

Coronal dimming parameters and their variations in the 24th solar cycle

We analyzed coronal dimming parameters and their relation to coronal mass ejections to determine the location of possible ejections sources on the solar disk in the 24th solar cycle. We used Solar Demon database that contains flares and dimmings parameters obtained from SDO/AIA image. Coronal mass ejections from the CACTus database were associated with 16% of all the dimmings for the period 2010–2018. On average, dimmings associated with coronal mass ejections are events with large absolute parameter values. Correlation coefficient between dimming position angle and associated coronal mass ejection position angle is 0.96. Correlation coefficients between the coronal mass ejection speed and dimming parameters are close to 0.5 for dimmings in the central region of the solar disk. Obtained results can be used to model coronal mass ejections propagation and to define the probability of their arrival in near-Earth space.

Tunable spectral continuous shift of high-order harmonic generation in atoms by a plasmon-assisted shaping pulse

We delve into the phenomenon of high-order harmonic generation within a helium atom under the influence of a plasmon-assisted shaping pulse. Our findings reveal an intriguing manipulation of the frequency peak position in the harmonic emission by adjusting the absolute phase parameter within the frequency domain of the shaping pulse. This phenomenon holds potential significance for experimental setups necessitating precisely tuned single harmonics. Notably, we observe a modulated shift in the created harmonic photon energy, spanning an impressive range of 1.2 eV. This frequency peak shift is rooted in the asymmetry exhibited by the rising and falling edges of the laser pulse, directly influencing the position of the peak frequency emission. Our study quantifies the dependence of this tuning range and the asymmetry of the laser pulse, offering valuable insights into the underlying mechanisms driving this phenomenon. Furthermore, our investigation uncovers the emergence of semi-integer order harmonics as the phase parameter is altered. We attribute this discovery to the intricate interference between harmonics generated by the primary and secondary return cores. This observation introduces an innovative approach for generating semi-integer order harmonics, thus expanding our understanding of high-order harmonic generation. Ultimately, our work contributes to the broader comprehension of complex phenomena in laser-matter interactions and provides a foundation for harnessing these effects in various applications, particularly those involving precise spectral control and the generation of unique harmonic patterns.

Envelope correction for shear-longitudinal collinear wave mixing to extract absolute nonlinear acoustic parameters

This paper addresses the effect of the excitation envelope on the generated nonlinear resonant signal (NRS) for collinear wave mixing of shear and longitudinal waves. The aim is to explore how the absolute material nonlinearity can be extracted accurately for any enveloped sinusoidal excitation signal. A finite difference time domain (FDTD) model was built to simulate the effect of input waveforms on the NRS. A change in the measured nonlinearity was seen as the input waveforms were changed from rectangular to Hanning windowed tone burst. The required waveform correction was derived theoretically and validated against the FDTD simulation. Experimental measurements were carried out for different waveforms at several input amplitudes, demonstrating its influence over the NRS. The theoretically derived correction factor, which is required to map the small NRS to the rectangular tone burst resonant amplitude, was validated experimentally. The correction was then used to extract one the fundamental Murnaghan constant (m). Comparatively, Hanning tone burst inputs showed lower variance in the extracted material property due to better control of the frequency bandwidth, relative to that of the transducers. This opens the opportunity to using Hanning windowed tone burst inputs reliably for the measurement of the absolute nonlinearity parameter and m through collinear shear-longitudinal wave mixing.

The Effect of Month-Long Daily Fasting on Semen Parameters: A Retrospective Cohort Study

Objective: The aim of the study was to determine whether Ramadan month-long daily fasting affects semen analysis parameters. Methods: This retrospective cohort study was conducted in tertiary academic medical center. Medical records of 97 Muslim patients who were admitted to the IVF unit from May 2011 to May 2021 were reviewed. Only men who provided at least one semen sample during Ramadan period (Ramadan month +70 days after) and one sample not during Ramadan were included. Semen characteristics of each patient were independently compared to themselves. Results: The post-gradient semen analysis indicated significantly lower progressive sperm motility (mean 30.01 ± 20.46 vs. 38.12 ± 25.13) (p < 0.001). The decrease in the progressive motility remained significant among patients with non-male factor indications (p < 0.001). In the non-male factor indication group, the difference in the progressive motility of the post-gradient semen analysis between the 2 samples was not statistically significant (p = 0.4). There were no significant differences between semen parameters before centrifuging. The incidence of asthenospermia (progressive sperm motility <32%) as an absolute parameter was higher after centrifuging the semen sample during the Ramadan period (p = 0.04). Conclusions: Semen samples collected during Ramadan period were associated with lower progressive motility and reduced semen volume compared to semen samples from the same men outside of the Ramadan period. A possible effect of these altered semen parameters on fertility should be investigated further.

The influence of thermal-hygrometric properties of air on the tune of pipe-organs

Pipes of pipe-organ dynamically change their tune during the year due to environmental conditions, sometimes consistently, making these instruments hard to be played. Because thermal-hygrometric properties of air change through the seasons, this study investigates the influence of air temperature and relative humidity on pipes' tune by monitoring a real pipe organ during a year. Normalized frequency was introduced to analyze and compare notes and logs of different extents with each other, and a variation within 7% was reported. Absolute Humidity parameter was introduced to gather temperature and relative humidity under a single parameter, allowing the evaluation of the contribution of the relative humidity to the frequency changes. Fitting models and their equations were extracted, and normalized residuals were estimated. The same analyses were performed on a small pipe organ at a laboratory scale to confirm the reliability of those models. A comparison between standard equations for calculating the resonance frequency of pipes and the introduced models is also discussed. Finally, the slight influence of humidity on the sounding frequency was confirmed. K/coefficients were introduced to align the results of the longitudinal resonance frequency equation for cylindrical cavities from literature with the resulting model by comparing the temperature influence.

Optimal sufficient requirements on the embedded Ising problem in polynomial time

One of the central applications for quantum annealers is to find the solutions of Ising problems. Suitable Ising problems, however, need to be formulated such that they, on the one hand, respect the specific restrictions of the hardware and, on the other hand, represent the original problems which shall actually be solved. We evaluate sufficient requirements on such an embedded Ising problem analytically and transform them into a linear optimization problem. With an objective function aiming to minimize the maximal absolute problem parameter, the precision issues of the annealers are addressed. Due to the redundancy of several constraints, we can show that the formally exponentially large optimization problem can be reduced and finally solved in polynomial time for the standard embedding setting where the embedded vertices induce trees. This allows to formulate provably equivalent embedded Ising problems in a practical setup.

Emission or scattering? Discriminating the origin of responsiveness in AIEgen‐doped smart polymers using the TPE dye

AbstractAggregation‐induced emission (AIE) luminogens are attractive dyes to probe polymer properties that depend on changes in chain mobility and free volume. When embedded in polymers the restriction of intramolecular motion (RIM) can lead to their photoluminescence quantum yield (PLQY) strong enhancement if local microviscosity increases (lowering of chain mobility and free volume). Nonetheless, measuring PLQY during stimuli, i.e. heat or mechanical stress, is technically challenging; thus, emission intensity is commonly used instead, assuming its direct correlation with the PLQY. Here, by using fluorescence lifetime as an absolute fluorescence parameter, it is demonstrated that this assumption can be invalid in many commonly encountered conditions. To this aim, different polymers are loaded with tetraphenylenethylene (TPE) and characterized during the application of thermal and mechanical stress and physical aging. Under these conditions, polymer matrix transparency variation is observed, possibly due to local changes in refractive index and to the formation of microfractures. By combining different characterization techniques, it is proved that scattering can affect the apparent emission intensity, while lifetime measurements can be used to ascertain whether the observed phenomenon is due to modifications of the photophysical properties of AIE dyes (RIM effect) or to alterations in the matrix optical properties.

RANCANG BANGUN ANTENA MONOPOLE MIKROSTRIP MENGGUNAKAN DEFECTED GROUND STRUCTURE BENTUK PERSEGI UNTUK OPTIMASI BANDWIDTH PADA APLIKASI KOMUNIKASI ULTRA-WIDEBAND

The development of UWB technology is very helpful in supporting high-speed data access. UWB offers a solution for large capacity for wide bandwidth. The frequency range for UWB systems between 3.1–10.6GHz will cause interference to wireless communication systems via wireless local area networks (WLANs) for IEEE 802.11a operating at 5.15–5.35GHz and 5.725–5.825GHz. This research aims to obtain a design of a rectangular printed monopole patch microstrip antenna and a slit using the Defected Ground Structure (DGS) technique to obtain bandwidth optimization on the UWB spectrum. For the implementation of the antenna design, the simulation method is used with the support of the RT/ Duroid substrate material. Realization of the design with the results of a manufactured antenna prototype with a minimalist size. The simulation and measurement results of the Absolute UWB bandwidth parameter at return loss &lt; -10 dB (VSWR &lt;2) the measurement value is 600MHz narrower than the simulation and for fractional bandwidth the measurement value is narrower by 0.21%. Resonance at the 5.2GHz frequency produces polarization with a gain value of 3.29dBi, omnidirectional and vertical polarization. As a prototype antenna to support the application of indoor wireless access communication devices that are low profile, compact with minimalist dimensions.

PHOTOMETRIC ANALYSIS OF ECLIPSING BINARIES: VY UMI, RU UMI AND GSC 04364-00648

We present the photometric analysis of BVR and TESS light curves of three eclipsing binaries, together with their period changes considering archival data and new minima times from our and TESS observations. For the first time we detected wave-like variations with low-amplitude in O − C residua of RU UMi, which can be interpreted as a consequence of the light-time effect caused by the 3rd component with period 7370 days. The period increase detected in the VY UMi system corresponds to mass transfer from the secondary to the primary component. For the GSC 04364-00648 binary system we find quadratic changes on the O − C diagram, which correspond to a period decrease. We cannot make assumptions about their nature, mainly due to short time of observation and uneven coverage of O − C diagram. We also determined the absolute parameter of their components using the photometric solution and GAIA distances.

On the homogeneity of SnIa absolute magnitude in the Pantheon+ sample

ABSTRACT We have analysed the Pantheon+ sample using a new likelihood model that replaces the single Type Ia supernovae (SnIa) absolute magnitude parameter M used in the standard likelihood model of Brout et. al. with two absolute magnitude parameters (M&amp;lt; and M&amp;gt;) and a transition distance (dcrit) that determines the distance at which M changes from M&amp;lt; to M&amp;gt;. The use of this likelihood dramatically changes the quality of fit to the Pantheon+ sample for a Lambda cold dark matter background by Δχ2 = −19.6. The tension between the M&amp;lt; and M&amp;gt; best-fitting values is at a level more than 3σ with a best-fitting dcrit very close to $20\, \mathrm{Mpc}$. The origin of this improvement of fit and M&amp;lt;–M&amp;gt; tension is that the new likelihood model successfully models two signals hidden in the data: (1) the volumetric redshift scatter bias systematic and (2) a mild signal for a change of intrinsic SnIa luminosity at about $20\, \mathrm{Mpc}$. This interpretation of the results is confirmed by truncating the z &amp;lt; 0.01 Hubble diagram data from the Pantheon+ data where the above systematic is dominant and showing that the M&amp;lt;–M&amp;gt; tension decreases from above 3σ to a little less than 2σ. It is also confirmed by performing a Monte Carlo simulation, which shows that the maximum significance of the SnIa luminosity transition ($\Sigma \equiv \frac{|M_{\gt} -M_{\lt} |}{\sqrt{\sigma _{M_{\gt} }^2+\sigma _{M_{\lt} }^2}}$) as obtained from the real SH0ES data is larger than the corresponding maximum significance of $94{{\ \rm per\ cent}}$ of the corresponding homogeneous simulated samples.

An Online Condition-Based Parameter Identification Switching Algorithm for Lithium-Ion Batteries in Electric Vehicles

Safely and reliably managing the lithium-ion batteries in electric vehicles for daily operations relies on accurate state-of-charge estimation. To pursue accurate state-of-charge estimation, battery electric circuit model-based algorithms demand minimized modeling error from accurate parameter identifications. Typical online parameter identification algorithms: least square fitting approach and recursive least square fitting are commonly adopted but have their limitations and issues with continuously providing accurate identification results. To overcome their problems and utilize their strengths, this paper proposes a condition-based parameter identification switching algorithm. The proposed algorithm accurately and robustly identifies the lithium-ion batteries' parameters based on the battery data condition and the adoption of Bollinger bands. By minimizing the modeling error, the accuracy of the state-of-charge estimation is thus improved. The electric vehicle simulation results indicate that the proposed algorithm can improve the parameter identification accuracy by an average of 70.80% and 44.95% reduction in the mean absolute parameter identification error, compared to typical least square fitting and recursive least square fitting approaches. With the help of the minimized modeling error, the state-of-charge estimation accuracy can thus be improved, rendering an average of 62.44% and 21.49% improvement.

Generalized Space-Time Autoregressive Modeling of the Vertical Distribution of Copper and Gold Grades with a Porphyry-Deposit Case Study

We examined the first-order application of the generalized space-time autoregressive GSTAR (1;1) model. The autoregressive model was used and was performed simultaneously in multiple drill-hole locations. The GSTAR model was applied to data with absolute time parameter units, such as hours, days, months, or years. Here a new perspective on modeling space-time data is raised. We used the relative time parameter index as a discretization of the same drilling depth of mineralization through a porphyritic deposit. Random variables were the copper and gold grades derived from the hydrothermal fluid that passed through the rock fractures in a porphyry copper deposit in Indonesia. This research aims to model the vertical distribution of copper and gold grades through backcasting the GSTAR (1;1) model. Such results could help geologists to predict copper and gold grades in deeper zones in an ore deposit. Two spatial weight matrices were used in the GSTAR (1;1) model, and these were based on a Euclidean distance and kernel function. Both weight matrices were constructed from different perspectives. The Euclidean distance approach gave a fixed weight matrix. Meanwhile, the kernel function approach gave the possibility to be random since it is based on real observations. It is obtained that the estimated (in-sample) and predicted (out-sample) kernel weight approach was accurate. Copper and gold grades data could recommend the GSTAR (1;1) model with a spatial kernel weight for modeling the vertical continuity case.

Convolutional neural networks for the classification of guitar effects and extraction of the parameter settings of single and multi-guitar effects from instrument mixes

Guitar effects are commonly used in popular music to shape the guitar sound to fit specific genres, or to create more variety within musical compositions. The sound not only is determined by the choice of the guitar effect, but also heavily depends on the parameter settings of the effect. Previous research focused on the classification of guitar effects and extraction of their parameter settings from solo guitar audio recordings. However, more realistic is the classification and extraction from instrument mixes. This work investigates the use of convolution neural networks (CNNs) for the classification and parameter extraction of guitar effects from audio samples containing guitar, bass, keyboard, and drums. The CNN was compared to baseline methods previously proposed, like support vector machines and shallow neural networks together with predesigned features. On two datasets, the CNN achieved classification accuracies 1-5,% above the baseline accuracy, achieving up to 97.4, % accuracy. With parameter values between 0.0 and 1.0, mean absolute parameter extraction errors of below 0.016 for the distortion, below 0.052 for the tremolo, and below 0.038 for the slapback delay effect were achieved, matching or surpassing the presumed human expert error of 0.05. The CNN approach was found to generalize to further effects, achieving mean absolute parameter extraction errors below 0.05 for the chorus, phaser, reverb, and overdrive effect. For sequentially applied combinations of distortion, tremolo, and slapback delay, the mean extraction error slightly increased from the performance for the single effects to the range of 0.05 to 0.1. The CNN was found to be moderately robust to noise and pitch changes of the background instrumentation suggesting that the CNN extracted meaningful features.

Texture analysis of sonographic image of placenta in pregnancies with normal and adverse outcomes, a pilot study

IntroductionMany maternal and fetal morbidity and mortality from complications of pregnancy have been attributed to placenta abnormality. Placenta assessment in developing countries is mainly through ultrasonography which is subjective and prone to error. Objective assessment of placental abnormalities through texture analysis has been frequently done using magnetic resonance images with little done on ultrasound generated images, thus, the need for this study. The study is aimed at using statistical texture analysis in characterizing placenta tissue into normal and abnormal placenta as well as testing the accuracy of different texture analysis algorithms in differentiating placenta into normal and abnormal placental tissues. MethodsThis longitudinal study involved 500 ultrasound-generated placenta images from patients screened for adverse pregnancy outcomes in a private hospital in Enugu. These images were loaded onto an HP laptop for viewing. Two regions of interest were selected from the placenta tissue where texture features were extracted and were classified into normal and abnormal placentas using MaZda® software version 47 while the accuracy of the classification descriptors was assessed using WEKA classification algorithms. ResultsCo-occurrence matrix, run length matrix and histogram parameters differentiated normal placenta tissue from abnormal placental tissues (p-value <0.05) while variance is the only absolute gradient parameter that can differentiate normal placenta tissue from abnormal placenta tissues. All feature descriptors show high classification accuracy using KNN and ANN algorithms. ConclusionTexture analysis can differentiate normal placenta tissues from abnormal placenta tissue which will reduce the errors associated with subjective assessment of the placenta echogenicity. Implications for practiceIntegrating these computer-aided algorithms into our ultrasound machines will lead to early detection of abnormal placenta tissues as early management results in better pregnancy outcomes.