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The Ordos Basin, characterized by its abundant transitional shale gas resources, plays a significant role in Chinese oil and gas exploration industry. However, the complex sedimentary environment and lithofacies combination of transitional shale make it highly challenging for reservoir quality evaluation. Acknowledging the rapid development of artificial intelligence, particularly the extensive use of machine learning in geology, this study proposes a new approach to assess the quality of transitional shale reservoirs through the utilization of the Random Forest algorithm (RF). Firstly, the lithology identification chart and reservoir quality evaluation standard were established using data and logging curves, and the relevant datasets were constructed. Four logging curves (Acoustic curve (AC), Compensated Neutron Log (CNL), Density curve (DEN), Gamma Ray (GR)), which serve as input variables to reflect reservoir characteristics, were carefully selected, while reservoir quality classification was used as the output results. Subsequently, the RF model was constructed and trained using this dataset. By analyzing the confusion matrix, it was observed that the RF model achieved an impressive accuracy level of approximately 90%. The study confirmed RF's superiority through comparisons with five methods: Factor analysis, Bayesian discriminant analysis, Gaussian Mixture Model (GMM), K-Nearest Neighbors (KNN), Gradient Boosting Decision Tree (GBDT). The comparison results revealed that the RF model exhibited high reliability and practical efficiency. Additionally, the RF model is utilized to predict the thickness of Type I reservoirs in the study area. The results demonstrated remarkable success in confirming production data, further emphasizing the proficiency of the RF within the field of machine learning for evaluating transitional shale reservoirs. This method presents a valuable tool for assessing transitional shale reservoirs. [ABSTRACT FROM AUTHOR]

Diffracted wavefield carries high-resolution information about subwavelength geological structural elements crucial for imaging small-scale subsurface discontinuities. However, the presence of strong reflection often obscures weak diffraction, limiting the effective use of diffraction in depicting detailed small-scale structures. To obtain a high-resolution diffraction image, we present a novel two-phase diffraction separation method that combines pattern-based method and energy attenuation function of stationary reflection in migrated dip-angle gathers. In the first phase, the pattern-based method utilizes pattern operator to characterize non-stationary features of reflection in dip-angle gathers and effectively eliminates the reflection outside the stationary point. In the second phase, the energy attenuation function based on dip angle is used to further attenuate residual reflection near the stationary point. The conflicting dip angle often reduces the performance of dip-based energy attenuation methods. We introduce the covariance rate criterion to adaptively adjust the conflicting dip angle, so that the energy attenuation function can more accurately attenuate the residual reflection. The numerical experiment conducted on classic Sigsbee 2B model validates the efficacy of the proposed method in suppressing strong high-slope reflection while preserving details of small-scale faults and scatterers. The real data application demonstrates the performance of the method to highlight deep fractures, presenting additional potential reservoir-related structural insights. [ABSTRACT FROM AUTHOR]

This research discusses that cognitive processes such as memory, attention and creativity differ in students and professionals, among musicians and non-musicians, dealing with musical performance. The purpose of the study was to evaluate and compare the role of memory, attention and creativity as cognitive processes in musical performance, focusing on the differences between non-musicians and musicians. The sample involved 400 individuals, students and professionals, specialising in music and economics. The research instruments used by the scholars were the Wechsler Memory Scale, the Conners Performance Test, and the Torrance Tests of Creative Thinking. Musical students possessed better-developed auditory and short-term memory, while professional musicians had better auditory, visual working and short-term memory. Analysis of attention reveals that music students score better than non-musicians on all four aspects: inattention, impulsivity, sustained attention, and vigilance. For professionals, the key aspects are impulsivity and sustained attention with better results revealed in musicians. Creative thinking was the only factor where the differences were statistically significant in all five scales and the findings proved that creativity was better developed among musicians. This study provides an in-depth analysis and adds new knowledge to existing literature and empirical data on the cognitive processes associated with musical performance, focusing on memory, attention and creativity. By examining the differences between non-musicians and musicians, as well as students and professionals, the study provides insight into how musical performance can be used as a way to develop these cognitive processes. [ABSTRACT FROM AUTHOR]

Hot dry rock (HDR) resources are gaining increasing attention as a significant renewable resource due to their low carbon footprint and stable nature. When assessing the potential of a conventional geothermal resource, a temperature field distribution is a crucial factor. However, the available geostatistical and numerical simulations methods are often influenced by data coverage and human factors. In this study, the Convolution Block Attention Module (CBAM) and Bottleneck Architecture were integrated into UNet (CBAM-B-UNet) for simulating the geothermal temperature field. The proposed CBAM-B-UNet takes in a geological model containing parameters such as density, thermal conductivity, and specific heat capacity as input, and it simulates the temperature field by dynamically blending these multiple parameters through the neural network. The bottleneck architectures and CBAM can reduce the computational cost while ensuring accuracy in the simulation. The CBAM-B-UNet was trained using thousands of geological models with various real structures and their corresponding temperature fields. The method's applicability was verified by employing a complex geological model of hot dry rock. In the final analysis, the simulated temperature field results are compared with the theoretical steady-state crustal ground temperature model of Gonghe Basin. The results indicated a small error between them, further validating the method's superiority. During the temperature field simulation, the thermal evolution law of a symmetrical cooling front formed by low thermal conductivity and high specific heat capacity in the center of the fault zone and on both sides of granite was revealed. The temperature gradually decreases from the center towards the edges. [ABSTRACT FROM AUTHOR]

Diffraction separation is crucial for high-resolution imaging of small-scale and discontinuous geological bodies, which are associated with oil and gas migration paths, reservoir spaces, or geological hazards in engineering. Diffraction and reflection show different geometric forms in the seismic common-offset domain, where reflection shapes are linear and diffractions are in the form of hyperbolic curves. One main challenge in diffraction separation technology lies in effectively suppressing reflected energy while preserving the diffraction energy. Curvelet is a sparse transformation with angle classification. After applying the curvelet transformation, reflections tend to be concentrated in a few coefficient matrices, while diffractions exhibit the opposite behavior. Based on the significant difference between reflections and diffractions in the curvelet domain, a diffraction separation and imaging method using cascaded filters in the curvelet domain is proposed that includes adaptive high-pass and median filters. Previous methods have encountered challenges in effectively separating reflected waves from diffracted waves, often struggling to simultaneously suppress reflected energy and preserve diffraction energy. These limitations can lead to difficulties in accurately identifying small-scale geological features and discontinuities. In contrast, the proposed method overcomes these limitations by leveraging the advantages of the curvelet transform and the cascaded filtering approach in the curvelet domain. The curvelet transform's sparse representation and angle classification properties enable effective concentration of reflections and diffractions in separate coefficient matrices. By employing adaptive high-pass and median filters, we achieve enhanced suppression of reflected energy and preservation of diffraction energy. Numerical experiments demonstrate that the proposed method not only eliminated high-slope and horizontal reflections but also preserved the energy-level and polarity-reversal of diffractions. Field application further confirms its potential value in accurately identifying complex stratigraphic structures and small-scale discontinuities. [ABSTRACT FROM AUTHOR]

Owing to the rapid development of wireless communication, radar and pulse power technology, the electromagnetic environment faced by electronic systems is increasingly complex and the intensity of electromagnetic field can be significant. In this study, a new interference phenomenon was observed when the microwave pulses were injected into the gallium nitride (GaN) high electron mobility transistor (HEMT) power amplifier through the output port. We investigated the relationship between the peak power of reverse injection microwave pulses and the duration or the amplitude of the interference by effect experiments. The interference duration could reach the magnitude of millisecond. Deep traps in GaN HEMT power amplifiers are proved to be the cause of this interference effects. [ABSTRACT FROM AUTHOR]

Positive-intrinsic-negative (PIN) limiters are widely used to protect sensitive components from leakage power itself and adjacent high-power injection. Being the core of a PIN limiter, the PIN diode is possible to be burnt out by the external microwave pulses. Here, using a parallel computing program for semiconductor multi-physics effects designed by ourselves, we studied the influence of the thickness of the I layer and the anode diameter of the PIN diode on the maximum temperature change curve of the PIN diode limiter. The damage threshold criterion in the numerical simulation was first studied by comparing experimental results with simulation results. Then, we determined the impact of the structure on the thermal burnout effect induced by microwave pulses of PIN limiter diodes. [ABSTRACT FROM AUTHOR]

Diffraction separation is a vital key step for high-resolution imaging of small-scale geologic discontinuities. The multichannel singular-spectrum analysis (MSSA) algorithm has exhibited adequacy for diffraction separation and reflection suppression. However, the traditional MSSA algorithm is expensive because of the singular-value decomposition (SVD) operator. In addition, the common rank misidentification renders the diffraction separation highly rank-sensitive. Random noise caused by energy leakage is another problem for diffraction separation that is unresolved by the conventional MSSA. In this study, we propose a prestack diffraction separation method involving an improved MSSA algorithm. The new algorithm enables faster singular value estimation relative to the conventional SVD, with a diagonal Hankelization operator for artificial linear and random noise suppression, thereby enhancing the signal-to-noise ratio. Rank misidentification is alleviated by lowering the sensitivity to rank of the separated diffractions. Synthetic and field data are utilized to demonstrate the feasibility and superiority of the proposed method in computational efficiency and noise suppression compared with the conventional method. [ABSTRACT FROM AUTHOR]

Core OKI-152 is one of the best-dated late Holocene cores from the middle Okinawa Trough. The chronological framework and high resolution of this core can help better interpret the paleoclimatology and paleoceanography at centennial-millennial timescales. This core has been analyzed using the alkenone unsaturation index (UK′37) to determine the sea surface temperatures over the last 3.6 kyr. Temperatures obtained from the core-top sample and the 3.6-kyr-averaged temperatures correspond well to the mean annual sea surface temperature (SST) at this location. The SSTs were lower during three periods in 3.6–2.7, 2.0–1.0, and 0.6–0 cal kyr BP, which corresponded to the Neoglacial Period, Dark Age Cold Period, and Little Ice Age, respectively. The variations in the UK′37-derived SSTs in core OKI-152 were not correlated with the high-latitude North Atlantic climate but were synchronous with those of the western Pacific and the El Niño Southern Oscillation (ENSO) variability at low latitudes. When compared with SST signals from the southern Okinawa Trough, the differences in the SST (ΔSST) between the southern and middle Okinawa Trough over the past 3.6 kyr were mainly controlled by the input of freshwater from Taiwan. This result indicates that the East Asian monsoon could influence the SSTs in the Okinawa Trough by modulating precipitation. Modern observations, paleoceanographic proxies, and modeling studies are needed to further understand the interactions among the Okinawa Trough, Pacific Ocean, and East Asian monsoon system. [ABSTRACT FROM AUTHOR]

Diffractions with good illumination carry valuable subwavelength information below the Rayleigh limit and can be used for high-resolution imaging of small-scale discontinuous features. As diffractions are characterized by weak energy, diffracted wavefield separation is a key step before imaging of discontinuities. The traditional multichannel singular-spectrum analysis (MSSA) for diffraction separation considers the constant rank strategy. It is challenging to estimate the appropriate rank for various data. In this study, we propose a robust adaptive rank-reduction method for 3D diffraction separation and imaging. It utilizes the low-rank characteristics of reflections in the common-offset or poststack domain based on the MSSA algorithm. The method considers the kinematic and dynamic differences of reflections and diffractions, and combines the energy intensity and smoothed curvature to accurately estimate the rank thresholds as well as the ranks of the reflections and diffractions. Three-dimensional multilayer and complex synthetic examples are used to demonstrate the feasibility of the proposed method in removing reflections and separating diffractions and achieving high-resolution imaging with diffractions, which is helpful for seismic data interpretation. [ABSTRACT FROM AUTHOR]

The X-ray fluorescence (XRF) core scanning method is widely applied in studies of sedimentary paleoenvironments due to its convenient pretreatment, nondestructive characteristics, fast execution, continuous scanning, and high resolution. XRF core scanning for sediments is commonly used in the studies on the South China Sea. This study compares XRF-scanned intensities and measured inductively coupled plasma (ICP) elemental contents of core CS11 in the northeast South China Sea deep basin. The results show that the analyzed elements can be separated into three classes. Class I includes elements with high correlation coefficients, such as Ca, Sr, and Zr; Class II contains elements with average correlation coefficients, such as Fe, Mn, Ti, and Cu; and Class III comprises elements with low correlation coefficients, such as K, Ni, Zn, Rb, and Al. In the South China Sea deep basin, pore water, compaction, and grain size have weak effects on the elemental intensities and contents of short core sediments. Hence, for elements with high correlation coefficients, a linear relationship model can be established by the least-squares method, in which the converted XRF intensities are approximately equal to the measured ICP contents. Based on the established log-ratio calibration model, the resulting ln(K/Ca), ln(Ti/Ca), ln(Fe/Ca), and ln(Zr/Ca) values generally display the same variation trends as the measured curves. The elemental contents and ratios produced by the linear model via the least-squares method and the log-ratio calibration model are expected to provide high-resolution data support for future paleoenvironmental research on the South China Sea deep basin. [ABSTRACT FROM AUTHOR]

Positive-intrinsic-negative (PIN) diodes are widely used as limiters to protect sensitive components from damage in radio frequency (RF) receiver systems and communication front-ends. However, PIN diode limiters can be burnt out due to the microwave pulses coupling through the front-end of RF receiver systems. The damage processes and mechanisms in PIN limiters are undoubtedly important topics. Here, the damage accumulation process in PIN limiters induced by external microwave pulses is studied via the injection experiments. The relationship between the degree of damage (i.e., insertion loss) in the limiters and number of the injected pulses is reported. The maximum temperature criterion for burnout in PIN limiters is theoretically predicted and experimentally verified not accurate, and it is further observed that the insertion loss of the PIN diode limiter changes significantly only if more energy is injected into the limiter via microwave pulses. [ABSTRACT FROM AUTHOR]

Factors influencing millennial-scale variability in the thermocline depth (vertical mixing) and sea surface salinity (SSS) of the southern Okinawa Trough (OT) during the past 17,300 years were investigated based on foraminifer oxygen isotope records of the surface dweller Globigerinoides ruber sensu stricto and the thermocline dweller Pulleniatina obliquiloculata in the AMS C dated OKT-3 core. The thermocline depth is influenced by surface thermal buoyancy (heat) flux, in turn controlled by the annual mean insolation at 30°N and the strength of the East Asian winter monsoon (EAWM). Strong insolation and weak EAWM tend to increase buoyancy gain (decrease buoyancy loss), corresponding to shallow thermocline depths, and vice versa. Regional SSS is influenced by the global ice volume, the Kuroshio Current (KC), and vertical mixing. A deep thermocline coincides with a high SSS because strong vertical mixing brings more, saltier subsurface KC water to the surface, and vice versa. Local SSS (excluding the global ice volume effect) became lower in the northern OT than in the southern OT after ~9.2 ka, implying that Changjiang diluted water had stronger influence in the northern sector. SSS show no major changes during the Bølling/Allerød and Younger Dryas events, probably because the KC disturbed the North Atlantic signals. This argues against earlier interpretations of sea surface temperature records of this core. Wavelet and spectral analyses of the ΔδO (δO of P. obliquiloculata minus G. ruber s.s.) and δO records display 1,540-, 1,480-, 1,050-, 860-, 640-, and 630-year periods. These are consistent with published evidence of a pervasive periodicity of 1,500 years in global climate as well as EAWM and KC signatures, and a fundamental solar periodicity of 1,000 years and intermediary derived periodicity of 700 years. [ABSTRACT FROM AUTHOR]

In this study, we investigated the electrical properties and the strain of the AlGaN/AlN/GaN heterostructure field-effect transistors with Ni/Au gate electrodes using the measured capacitance-voltage (C-V) and current-voltage (I-V) characteristics and the polarization effect of the heterostructures. We found that the Ni/Au gate electrode showed a good thermal stability when the RTA temperature is below 400 °C; however, with further increase in the annealing temperature, the 2DEG sheet density under the Ni/Au Schottky contact started to decline dramatically, and the device started to exhibit bad pinch-off characteristics after a 700 °C RTA. We also found that the RTA process could change the strain and even damaged the crystal structure of the barrier layer under the gate electrodes. [ABSTRACT FROM AUTHOR]

The source and processes controlling the deposition of the sand fraction of muddy seafloor sediments remain poorly understood. Surficial seafloor sediments were collected offshore of the Eastern Shandong Peninsula and were analyzed regarding their detrital heavy mineral constituents and grain size distributions to determine their spatial distribution patterns, sand fraction provenance, and transport pathways. Five sediment types were identified in the study area: clayey silt, silt, sandy silt, silty sand, and sand. Each of these sediment types displayed distinct grain size parameters of their corresponding sand fractions. Moreover, three statistical clusters of sand grains were identified, suggesting variations in provenances and sedimentary processes from one cluster to the next. Twenty-five species of detrital heavy minerals in the sand fraction were identified and then assigned to four categories based on their mineral stability (i.e., ultrastable, stable, moderately stable, and unstable). The sandy sediments were enriched in ultrastable and stable heavy minerals, indicating that these sand grains mostly originated from coastal erosion of granitic and/or metamorphic rocks. In contrast, the muddy sediments were characterized by unstable heavy minerals dominated by hornblende and epidote. The results of principal component analysis further suggested that these sand grains are similar in terms of their provenance (coastal erosion) but have undergone complex sedimentary processes. Relative sea level changes during the late Quaternary caused shifts in the sediment sources and supplies, which were the primary factors controlling the grain sizes of the sand fractions and heavy mineral assemblages in the surficial sediments of the study area. [ABSTRACT FROM AUTHOR]

From the capacitance-voltage curves and current-voltage characteristics of the InAlN/AlN/GaN heterostructure field-effect transistors (HFETs) with side-Ohmic contacts and normal-Ohmic contacts, two-dimensional electron gas (2DEG) electron mobility was calculated. It is found that the polarization Coulomb field scattering (PCF) is closely related to the normal-Ohmic contact processing, and the PCF was weakened by side-Ohmic contact processing in InAlN/AlN/GaN HFETs, similar to that in AlGaN/AlN/GaN HFET devices. Further, due to the stronger spontaneous polarization in the thinner InAlN barrier layer, the influence of the gate bias on the PCF in InAlN/AlN/GaN HFETs is greater than that in AlGaN/AlN/GaN HFETs. As a result, the PCF in InAlN/AlN/GaN HFETs with side-Ohmic contacts is stronger than that in AlGaN/AlN/GaN HFETs with side-Ohmic contacts. Moreover, the 2DEG electron density in the InAlN/AlN/GaN HFETs with side-Ohmic contacts is increased by more than twice compared with the 2DEG electron density in the InAlN/AlN/GaN HFETs with normal-Ohmic contacts. [ABSTRACT FROM AUTHOR]

Integrated analyses of grain size, Pb stable isotope, and heavy metals were performed to characterize the sedimentary core LDC30 collected from the southeastern Liaodong Bay of China and investigate the 100-year history of heavy metal accumulation. The aluminum-normalized enrichment factors and the excess metal fluxes (MF) indicated that the metal accumulation in the southeastern Liaodong Bay occurred in three stages: a pre-industrial stage (prior to 1960s) with natural accumulation, an initial industrial stage (1960-1990) with slowly elevated accumulation, and an industrialized stage (post-1990s) with accelerated accumulation. A moderate enrichment of Cd and Pb (up to 4.1- and 2.6-fold over the baseline, respectively) and a slight enrichment of Cr, Cu, Ni, and Zn (up to 1.3-fold) were measured in the recent sediments. Multivariate analysis demonstrated that the Cr, Cu, Ni, and Zn were from the natural origin, whereas Cd and Pb from the anthropogenic origin. The MF of Cd and Pb showed a drastically increasing trend since 1990s, which could result from the intensive application of fertilizers and combustion of fossil fuels. [ABSTRACT FROM AUTHOR]

In an effort to assess the potential contamination and determine the environmental risks associated with heavy metals, the surface sediments in Liaodong Bay, northeast China, were systematically sampled and analyzed for the concentrations of Cu, Pb, Zn, Cr, Ni, As, and Hg. The metal enrichment factor (EF) and geoaccumulation index ( I) were calculated to assess the anthropogenic contamination in the region. Results showed that heavy metal concentrations in the sediments generally met the criteria of China Marine Sediment Quality (GB18668-2002); however, both EF and I values suggested the elevation of Pb concentration in the region. Based on the effect-range classification (TEL-PEL SQGs), Cu, Pb, Ni, and As were likely to pose environment risks, and the toxic units decreased in the order: Ni > Pb > Cr > Zn > As > Cu > Hg. The spatial distribution of ecotoxicological index (mean-ERM-quotient) suggested that most of the surface sediments were 'low-medium' priority zone. Multivariate analysis indicated that the sources of Cr, Ni, Zn, Cu, and Hg resulted primarily from parent rocks, and Pb or As were mainly attributed to anthropogenic sources. The results of this study would provide a useful aid for sustainable marine management in the region. [ABSTRACT FROM AUTHOR]

The concentrations of heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn) and organic carbon in surface sediments, collected from the southern Bohai Bay, were determined to assess the potential contamination and determine the environmental risks associated with heavy metals. Results showed that heavy metal concentrations in the sediments generally met the China Marine Sediment Quality criteria. Both the ecotoxicological index and the potential ecological risk index suggest that the combined ecological risk of the six studied metals may be low, with the highest ecotoxicological potential zones located in the offshore area. The methods of enrichment factor and geoaccumulation index suggested that elevated concentrations of Cd, Cr, and Ni are presented in the region. Multivariate analysis also indicated that the lithogenic factor dominates the distribution of most part of the considered metals in the study area, whereas Cd and Cr are clearly influenced by anthropogenic inputs. The results of this study are likely to be a useful tool to authorities in charge of sustainable marine management. [ABSTRACT FROM AUTHOR]

Based on 17 AMSC age data, we reconstructed high-resolution records of sea surface primary productivity (PP) in the southern Okinawa Trough (MD05-2908) over the last 6.8 ka BP using the calcareous nannofossil carbon isotope and the relative percentage contents of Florisphaera profunda indexes. The underlying mechanism controlling the sea surface PP was then discussed. The sea surface PP, indicated by the coccolith δC and %Fp conversional equations, decreased with some fluctuations since 6.8 ka BP. This decrease may be connected to the decreased terrigenous input resulting from the reduced East Asian Summer Monsoon (EASM) precipitation. Both the periods of 4-2 ka BP (PME) and 6.8-4.8 ka BP were characterized by relatively higher PP. The former was mainly controlled by the weakening of the Kuroshio Current, whereas the latter mainly resulted from the greater terrigenous input associated with the stronger EASM. [ABSTRACT FROM AUTHOR]