Analytic Signal Analysis Research Articles

Quantitative ultrasonic imaging of weave structure in textile composites

Textile composites owe their desirable mechanical properties to the intricate fabric architecture. However, manufacturing deviations can influence these attributes, significantly affecting their mechanical performance. Thus, ensuring the quality and structural integrity of fabric architectures has become pivotal, leading to the advancement of ultrasonic non-destructive testing techniques. However, existing techniques, primarily tailored for unidirectional laminates, often struggle with weave pattern extraction, given the complex features of fabric laminates. To address this gap, a pulse-echo ultrasound coupled to a 2D analytic-signal analysis is proposed. The 2D analytic-signal methodology autonomously discerns the complex ultrasound features from fabric laminates, streamlining weave pattern analysis. The study showcases ply-by-ply reconstruction of local weave patterns of fabric laminates with nominal layups of [#(0/90)]8 and [#(+45/−45)#(0/90)]5s, respectively. The efficacy of the methodology is ascertained through quantitative metrics, highlighting its innovative potential for through-depth extraction of local weave patterns in a swift and automated manner.

Stability and Reliability of Enhanced External-Internal Motion Correlation via Dynamic Phase-Shift Corrections Over 30-min Timeframe for Respiratory-Gated Radiotherapy.

To assess the stability of patient-specific phase shifts between external- and internal-respiratory motion waveforms, the reliability of enhanced external–internal correlation with phase-shift correction, and the feasibility of guiding respiratory-gated radiotherapy (RGRT) over 30 min. In this clinical feasibility investigation, external bellows and internal-navigator waveforms were simultaneously and prospectively acquired along with two four-dimensional magnetic resonance imaging (4DMRI) scans (6–15 m each) with 15–20 m intervals in 10 volunteers. A bellows was placed 5 cm inferior to the xiphoid to monitor abdominal motion, and an MR navigator was used to track the diaphragmatic motion. The mean phase-domain (MPD) method was applied, which combines three individual phase-calculating methods: phase-space oval fitting, principal component analysis, and analytic signal analysis, weighted by the reciprocal of their residual errors (RE) excluding outliers (RE >2σ). The time-domain cross-correlation (TCC) analysis was applied for comparison. Dynamic phase-shift correction was performed based on the phase shift detected on the fly within two 10 s moving datasets. Simulating bellows-triggered gating, the median and 95% confidence interval for the navigator's position at beam-on/beam-off and %harm (percentage of beam-on time outside the safety margin) were calculated. Averaged across all subjects, the mean phase shifts are found indistinguishable (p > .05) between scan 1 (55˚ ± 9˚) and scan 2 (59˚ ± 11˚). Using the MPD method the averaged correlation increases from 0.56 ± 0.22 to 0.85 ± 0.11 for scan 1 and from 0.47 ± 0.30 to 0.84 ± 0.08 for scan 2. The TCC correction results in similar results. After phase-shift correction, the number of cases that were suitable for amplitude gating (with <10%harm) increased from 2 to 17 out of 20 cases. A patient-specific, stable phase-shift between the external and internal motions was observed and corrected using the MPD and TCC methods, producing long-lasting enhanced motion correlation over 30m. Phase-shift correction offers a feasible strategy for improving the accuracy of tumor-motion prediction during RGRT.

Comparative study of ultrasonic techniques for reconstructing the multilayer structure of composites

The multilayer structure of fiber-reinforced polymers may be extracted by ultrasonic pulse-echo inspection. Depending on the employed ultrasonic frequency and subsequent processing methodology, different depth resolution and dynamic depth range can be achieved. This study compares the performance of different ultrasonic pulse-echo approaches for extracting the ply-by-ply structure of multilayered composites. The following methodologies are studied: Method 1: 50 MHz, 15 MHz, and 5 MHz ultrasound with low-pass filtering using analysis of the instantaneous amplitude, Method 2: 15 MHz ultrasound with Wiener deconvolution (and autoregressive spectral extrapolation) using analysis of the instantaneous amplitude, and Method 3: 5 MHz ultrasound with low-pass or log-Gabor filtering using analysis of the instantaneous phase. In the simulation study, the performance of the various techniques is investigated on synthetic data representative for a 24-ply carbon fiber reinforced polymer. The robustness of the techniques is evaluated for different signal-to-noise ratios. The various techniques are further investigated on experimental data of a 24-ply cross-ply carbon fiber reinforced polymer. The ply-by-ply structure is extracted and presented in the form of both B-scan and C-scan images. The thickness of each ply is estimated for quantitative analysis. The obtained results indicate that the 5 MHz ultrasound coupled to analytic-signal analysis with log-Gabor filter shows the best performance for reconstructing the multilayer structure of the studied composites.

Three-directional analytic signal analysis and interpretation of magnetic gradient tensor

Compared to conventional magnetic data, magnetic gradient tensor data contain more high-frequency signal components, which can better describe the features of geological bodies. The directional analytic signal of the magnetic gradient tensor is not easily interfered from the tilting magnetization, but it can infer the range of the field source more accurately. However, the analytic signal strength decays faster with depth, making it difficult to identify deep field sources. Balanced-boundary recognition can effectively overcome this disadvantage. We present here a balanced-boundary identification technique based on the normalization of three-directional analytic signals from aeromagnetic gradient tensor data. This method can effectively prevent the fast attenuation of analytic signals. We also derive an Euler inversion algorithm of three-directional analytic signal derivative. By combining magnetic-anomaly model testing with the traditional magnetic anomaly interpretation method, we show that the boundary-recognition technology based on a magnetic gradient tensor analytic signal has a greater advantage in identifying the boundaries of the geological body and can better reflect shallow anomalies. The characteristics of the Euler equation based on the magnetic anomaly direction to resolve the signal derivative have better convergence, and the obtained solution is more concentrated, which can obtain the depth and horizontal range information of the geological body more accurately. Applying the above method to the measured magnetic-anomaly gradient data from Baoding area, more accurate field source information is obtained, which shows the feasibility of applying this method to geological interpretations.

ANALYTIC SIGNAL AND RESERVOIR MODEL OF HATUASA-TALANGHAHA HOT SPRING, TULEHU, AMBON, INDONESIA BASED ON MAGNETIC DATA INVERSION

The earth magnetic field study has been carried out in Suli and Tulehu, Ambon island to study the geothermal systems that apply in the region, specifically the reservoir model in the Hatuasa and Talanghaha hot springs. These hot springs are located on the fault line, including the Banda and Banda-Hatuasa faults, southwestnortheast. The study was conducted by subsurface inversion modeling after performing an analytic signal analysis of magnetic data. The total magnetic field intensity in the geothermal regions of Suli and Tulehu ranges from -656 nT to 310 nT, which is dominated by high anomalies in Tulehu. Meanwhile, the reduce to pole (RTP) magnetic anomaly ranges from -1069.20 nT to 662.78 nT, which is dominated by low anomalies, where the Haasa and Talanghaha hot springs are at low to middle anomalies. The analytic signal analysis of magnetic data clearly shows the geological boundaries in the study area. Inversion modeling of magnetic anomaly produces contrast susceptibility of rocks ranging from -0.042 SI to 0.043 SI. The reservoir layer as a place for geothermal fluid under the Hatuasa - Talanghaha hot springs is generally associated with low susceptibility contrast at depths reaching 500 m-1000 m. The cap rock is 500 m deep with a susceptibility value of 0.0035 SI-0.0065 SI and the heat source is thought to originate from igneous intrusion in the study area.

Quantifying API polymorphs in formulations using X-ray powder diffraction and multivariate standard addition method combined with net analyte signal analysis

The direct quantification of Active Pharmaceutical Ingredients in solid formulations is a challenging open issue. A consolidated analytical technique based on X-ray Powder Diffraction is available, being the definitive test for the identification of polymorphs and crystal phases. However, its application for quantitative analysis is hindered by matrix effects: refinement methods (e.g. Rietveld method) require a complete knowledge of samples' composition, while univariate calibration methods require the matrix effect to be studied and severely suffer from the co-presence of crystalline and amorphous phases in the sample. Multivariate analysis is the only way to bypass problems affecting refinements procedures and univariate calibration. In particular, the multivariate standard addition method (SAM) is promising; however, it is straightforward only when the analytical blank (matrix devoid of analyte) is available: in that case SAM is applied by simply extrapolating the SAM model to the matrix experimental signal. In this work, the quantitative analysis of polymorphic forms of Active Pharmaceutical Ingredients based on X-ray Powder Diffraction is performed for the first time by a method based on multivariate standard addition method combined with net analyte signal procedure; it allows for reliable quantification of polymorphs of active principles in solid formulations, which are rapidly analyzed without any sample pre-treatment. Two test cases are presented: quantification of two polymorphs of piracetam in binary mixtures (forms II and III), and quantification of paracetamol (form I) in Tachifludec®.

New data on neotectonic contractional structures in Precordillera, south of Río de La Flecha: Structural setting from gravity and magnetic data. San Juan, Argentina

The Central and Eastern Precordillera form oppositely verging thrust systems on the western and eastern sides of the Matagusanos-Maradona-Acequión valley, establishing a thick-skinned triangle zone with significant changes in the axis position along strike. Between the del Agua and the de La Fecha rivers, the axis of this triangular zone is located in the eastern portion of the depression. Changes in the position of the triangle zone axis along strike, whether to the east or to the west, took place during Pliocene–Pleistocene times. Geophysical and geodetic data indicate a subsurface structure striking NE, oblique to the general direction of the foreland with dextral displacement. Accordingly, the change in the location of the triangular area could be attributed to stress transfer controlled by heterogeneities in the basement. By analytic signal analysis of magnetic anomalies, it is possible to assess the regional structural coupling between Pie de Palo and Eastern Precordillera. The oblique arrangement of basement blocks could explain transverse lineaments and the sigmoidal geometry of the Eastern Precordillera. Geophysical and geological evidence shows that the depression is crossed by several E–W strike-slip faults. These faults possibly controlled the position of the triangle zone axis until Neogene–Pleistocene times by transferring displacements and provoking its jump along strike.Basement structures might have also played a primary role in the location of Quaternary faults trending N–S. Finally, the east–west cross-section geophysical model shows the triangular zone, responding to the different controls imposed by the pre-existing basement structures.

Determination of Figures of Merit for Near-Infrared, Raman and Powder X-ray Diffraction by Net Analyte Signal Analysis for a Compacted Amorphous Dispersion with Spiked Crystallinity

With the growing interest in solubility enhancement of drugs via solid dispersion formulations, it is becoming more crucial to find appropriate analytical methods for detection of amorphous destabilization (i.e., crystallization). The objective of this work was to compare the performance of reflectance and transmittance near-infrared spectroscopy and Raman spectroscopy methods with powder X-ray diffraction. Specifically, the methods were compared on their ability to detect low concentrations (0–2 % w/w) of crystalline indomethacin-consolidated dispersions. Partial least squares regression and net analyte signal analyses were performed for the computation of figures of merit. Based on the calibration error statistics, all methods were suitable for the quantitative determination indomethacin content above 0.5 % (w/w) or 1 % (w/w) of drug content. However, the sensitivity, selectivity, limit of detection, and data collection time found for the near-infrared reflectance measurements provides the greatest promise for future online stability monitoring of consolidated dispersions.

3D geophysical characterization of the Sulu–Dabie orogen and its environs

In an effort to further advance our understanding of the evolution of the Sulu–Dabie orogen and its complex interactions with the Tanlu fault, and to tackle non-unique geophysical interpretations, we characterize the 3D geological structures and dynamics of the Sulu–Dabie orogen and its environs using various data processing and interpretation of a very large suite of gravimetric, magnetic, magnetotelluric, geothermal, and seismic data. We have modeled regional geothermal field of the lithosphere by incorporating both surface heat flow and Curie-point depths inverted from magnetic anomalies. This gives better constraints on regional thermal lithospheric thicknesses, which are found to be small (mostly between 55 and 95km), conformable to other geophysical results, and supportive of lithospheric de-rooting. From regional geotherms and Bouguer gravity anomalies, we assess depths, temperatures and heat flow of the Moho, and find that mantle contributes a little over 70% of the total surface heat flow. Large differences in thermal lithospheric thicknesses and geothermal activities are found between the Sulu and the Dabie segments of the Sulu–Dabie orogen. These differences result, at least partially, from large vertical differential movement at the lithospheric scale across the Tanlu fault, as seen from both reflection seismic sections and gravity anomalies. Within the Sulu–Dabie orogenic belt, reduction to the pole and 3D analytic signal analysis on magnetic anomalies reveal that positive magnetic anomalies associated with this belt are most due to gneiss, migmatite and Mesozoic granites, whereas ultrahigh-pressure metamorphic zones show weak or negative magnetic anomalies. This interesting magnetic contrast between ultrahigh-pressure metamorphic rocks and surrounding rocks suggests that ultrahigh-pressure metamorphic minerals are either only weakly magnetized, or possibly retrograded and remagnetized over a long time span or in a period of reversed magnetization. High-pressure metamorphic minerals of blueschist facies appear to be less susceptive than ultrahigh-pressure metamorphic minerals.

Ground Magnetic Investigation of Subsurface Structures Affecting Wadi Thuwal Area, KSA

Ground magnetic survey was carried out in Wadi Thuwal area, north of Jeddah, during winter and spring of 2007-2009. The survey was intended to delineate the subsurface structures and covered an area of about 130 km 2 , located between latitudes 22° 10' 00 N and 22° 16' 53.5 N and longitudes 39° 06' 40 E and 39° 16' 20 E. The survey was conducted along profiles taking EW and NS directions. The field data were reduced and then interpolated to produce a high resolution total intensity ground magnetic map (HRTMI). Shaded relief maps have been effective in showing structural trends and characteristic anomaly patterns. Magnetic susceptibility measurements (k) were attended throughout the entire ground survey. The depth to the sources of the ground-magnetic anomalies was estimated using 2D and 3D Euler deconvolution. Observed surface faults are expected to be initiated from the basement. 2D and 3D analytic signal analysis and derivative maps show several trends crossing the study area. These trends, which are attributed to faults or contacts, are extended to the east of the study area, and further to the Arabian Shield (East), where some of them represent major faults that evidently have an impact on the water distribution potentiality of the Wadi. These trends are basically taking NE-SW faults direction, the rift shoulder master faults with N-S direction, NW-SE, and NNE-SSW normal faults direction. The Euler deconvolution analysis using N=1, reveals distinctive patterns of subsurface dikes. These may be attributed to dike swarms trending NW-SE and NNW-SSE. Keyword: Magnetic, Thuwal, 3D Euler deconvolution, analytic signal.

Determination of figures of merit for near-infrared and raman spectrometry by net analyte signal analysis for a 4-component solid dosage system

Process analytical technology has elevated the role of sensors in pharmaceutical manufacturing. Often the ideal technology must be selected from many suitable candidates based on limited data. Net analyte signal (NAS) theory provides an effective platform for method characterization based on multivariate figures of merit (FOM). The objective of this work was to demonstrate that these tools can be used to characterize the performance of 2 dissimilar analyzers based on different underlying spectroscopic principles for the analysis of pharmaceutical compacts. A fully balanced, 4-constituent mixture design composed of anhydrous theophylline, lactose monohydrate, microcrystalline cellulose, and starch was generated; it consisted of 29 design points. Six 13-mm tablets were produced from each mixture at 5 compaction levels and were analyzed by near-infrared and Raman spectroscopy. Partial least squares regression and NAS analyses were performed for each component, which allowed for the computation of FOM. Based on the calibration error statistics, both instruments were capable of accurately modeling all constituents. The results of this work indicate that these statistical tools are a suitable platform for comparing dissimilar analyzers and illustrate the complexity of technology selection.

Comparison of multivariate calibration models for glucose, urea, and lactate from near-infrared and Raman spectra

Partial least-squares (PLS) calibration models have been generated from a series of near-infrared (near-IR) and Raman spectra acquired separately from sixty different mixed solutions of glucose, lactate, and urea in aqueous phosphate buffer. Independent PLS models were prepared and compared for glucose, lactate, and urea. Near-IR and Raman spectral features differed substantially for these solutes, with Raman spectra enabling greater distinction with less spectral overlap than features in the near-IR spectra. Despite this, PLS models derived from near-IR spectra outperformed those from Raman spectra. Standard errors of prediction were 0.24, 0.11, and 0.14 mmol L(-1) for glucose, lactate, and urea, respectively, from near-IR spectra and 0.40, 0.42, and 0.36 mmol L(-1) for glucose, lactate, and urea, respectively, from Raman spectra. Differences between instrumental signal-to-noise ratios were responsible for the better performance of the near-IR models. The chemical basis of model selectivity was examined for each model by using a pure component selectivity analysis combined with analysis of the net analyte signal for each solute. This selectivity analysis showed that models based on either near-IR or Raman spectra had excellent selectivity for the targeted analyte. The net analyte signal analysis also revealed that analytical sensitivity was higher for the models generated from near-IR spectra. This is consistent with the lower standard errors of prediction.

Investigating the Groundwater Occurrence in Wadi Rahjan and Its Potential Contribution to Ain Zubaida Using Magnetic and Electric Methods, Makkah Al-Mukarramah, KSA

Ground magnetic and DC resistivity surveys are imple- mented to explore groundwater in the northern part of Wadi Rahjan, Makkah Al-Mukarramah, Saudi Arabia. This part includes the down- stream area of Wadi Rahjan which flows into Wadi Nu'man where Ain Zubida is located. A system of E-W dikes is shown on available geologic map, which is cutting across the surrounding metavolcanic rocks and Wadi Rahjan stream. This study aims to locating the exten- sions of these dikes/discontinuities that may control the groundwater flow and distribution along this important part of Wadi Rahjan. Ground magnetic survey is utilized along wadi Rahjan and the mag- netic data are presented as contour map. Selected nine profiles are quantitatively analyzed using analytic signal analysis and horizontal gradient techniques. The present study reveals four discontinuities representing most probably dikes crossing the wadi. These dikes have great impact on the groundwater flow from upstream side to down- stream side reaching wadi Nu'man where these dikes act as barriers for groundwater flow. Electrical resistivity sounding using Schlumberger array is used along the wadi to delineate the extent of saturation zones, depth to basement, and to clarify the possible occurrence of the groundwater accumulations. It can be used also to show the effect of dikes occurrence on the groundwater flow and its distribution along this part of the Wadi. The study was successful in locating the water saturated zone and in determining its extension along the downstream part at the south of a major dike that partially prevents the groundwater flow to wadi Nu'man.

The Application Of Fractional Calculus To Potential Field Data

Gradients of magnetic and gravity data are used routinely to enhance the edges of anomalies, or as input to interpretation techniques such as analytic signal analysis or Euler deconvolution. The most commonly used gradients are of first and second order, higher orders being used less frequently due to noise problems. This paper discusses the benefits of a generalized approach using fractional gradients, demonstrating their usefulness as an aid to interpretation, both on theoretical models and on aeromagnetic data from the Free State province, South Africa. Fractional horizontal gradients are suggested as a means of avoiding the instability problems present when magnetic data from low latitudes is reduced to the pole. They also allow the use of an improved sunshading algorithm that is less affected by noise than the standard method. Fractional vertical gradients may be used to generate both enhanced analytic signal data and enhanced Euler deconvolution solutions.

The application of fractional calculus to potential field data

Gradients of magnetic and gravity data are used routinely to enhance the edges of anomalies, or as input to interpretation techniques such as analytic signal analysis or Euler deconvolution. The most commonly used gradients are of first and second order, higher orders being used less frequently due to noise problems. This paper discusses the benefits of a generalized approach using fractional gradients, demonstrating their usefulness as an aid to interpretation, both on theoretical models and on aeromagnetic data from the Free State province, South Africa. Fractional horizontal gradients are suggested as a means of avoiding the instability problems present when magnetic data from low latitudes is reduced to the pole. They also allow the use of an improved sunshading algorithm that is less affected by noise than the standard method. Fractional vertical gradients may be used to generate both enhanced analytic signal data and enhanced Euler deconvolution solutions.

Aeromagnetic interpretation in a geotraverse area across the central Scandinavian Caledonides

Abstract Total magnetic field data have been measured and interpreted along selected profiles in an area through the Jämtland-Trøndelag Caledonides. The object has been to model local and regional structures and investigate their possible relevance for interpretation of Caledonian tectonics. Two different methods of interpretation have been applied: analytic signal analysis, and fitting of polygonal models: they yield partly consistent, partly supplementary results. With few exceptions, the Caledonian cover units are weakly magnetized and are only responsible for very local anomalies. The main anomalies derive from the autochthonous-parautochthonous crystalline basement. The prominent regional anomaly in the area (the Jämtland Anomaly) is found to originate from the Proterozoic sequence of Dala granites and volcanics that crop out in the autochthon south of the area and obviously continue northwards as a basement below the Caledonian rocks. It forms a huge rock volume, 500 km long, 200 km wide and about 10 km thick. The assigned magnetic susceptibility, 0.075 SI-units, is supported by the existing rock magnetic data. The magnetic model of the basement surface below the Caledonian cover shows a pattern of synforms and antiforms in general agreement with the existing geological information. However, a previously unpredicted antiform is found at the eastern front of the Offerdal Nappe near Landön. Caledonian activity appears to have shaped the basement surface. It may also be responsible, at least partly, for some internal structure in the Precambrian basement, such as is seen in the alignment of the regular linear western flank of the Jämtland Anomaly with the western limb of the Sylarna Antiform.