Temporal Field Research Articles

LGSNet: A Two-Stream Network for Micro- and Macro-Expression Spotting With Background Modeling

Micro- and macro-expression spotting in an untrimmed video is a challenging task, due to the mass generation of false positive samples. Most existing methods localize higher response areas by extracting hand-crafted features or cropping specific regions from all or some key raw images. However, these methods either neglect the continuous temporal information or model the inherent human motion paradigms (background) as foreground. Consequently, we propose a novel two-stream network, named Local suppression and Global enhancement Spotting Network (LGSNet), which takes segment-level features from optical flow and videos as input. LGSNet adopts anchors to encode expression intervals and selects the encoded deviations as the object of optimization. Furthermore, we introduce a Temporal Multi-Receptive Field Feature Fusion Module (TMRF <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{3}$</tex-math></inline-formula> M) and a Local Suppression and Global Enhancement Module (LSGEM), which help spot short intervals more precisely and suppress background information. To further highlight the differences between positive and negative samples, we set up a large number of random pseudo ground truth intervals (background clips) on some discarded sliding windows to accomplish background clips modeling to counteract the effect of non-expressive face and head movements. Experimental results show that our proposed network achieves state-of-the-art performance on the CAS(ME) <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{2}$</tex-math></inline-formula> , CAS(ME) <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{3}$</tex-math></inline-formula> and SAMM-LV datasets.

Optimal Design of a Third Pair of Gravity Satellites to Augment Two Existing Polar Pairs to Enhance Earth's Temporal Gravity Field Recovery

Optimal Design of a Third Pair of Gravity Satellites to Augment Two Existing Polar Pairs to Enhance Earth's Temporal Gravity Field Recovery

Managing movements, ordering and transformations of resource flow processes in course of implementing development project life cycles

Based on previous research of theory and methodology, authors describe and systematize the triune process of motion, ordering and qualitive and quantitative transformations ща the development process resource flows from the externally chaotic resource surrounding at macro-, meso, and micro-resource levels, to the organized project organizational and technological stages. Characteristics of different flows located at different resource levels and project stages of project life cycles from initiation through implementation, modernization and demolition of the assets were provided according to the “order of multipole various resource flow processes from their chaos” paradigm. Authors determined sources and ends of the unordered and ordered resource flow processes in course of project life cycles, defined conditions for process ordering and transformations at each resource level and project life cycle stage, and outlined goals, interests, tasks and areas of responsibility for development project stakeholders at different project life cycle stages. Authors perform analysis and forecasting of resource flow management processes for different project life cycle processes and resource levels based on the logistic relay model, and according to the proposed methodology of managing resource flow “triad” of flow motion, ordering, and transformations is a common spatial and temporal field of resource logistics.

Effect of myopia-control lenses on central and peripheral visual performance in myopic children.

To evaluate the short-term effects of three myopia-control lenses, which impose peripheral myopic defocus while providing clear central vision, on central and peripheral visual performance in myopic children. Twenty-one myopic children were enrolled in the study. Central visual performance was assessed using the quick contrast sensitivity function. Peripheral visual performance was evaluated by measuring peripheral contrast threshold and global motion perception, while subjects maintained fixation through the central portion of the lens. Single-vision spectacle lenses (SVL), spectacle lenses with highly aspherical lenslets (HAL) and defocus-incorporated soft contact (DISC) lenses were evaluated in random order, followed by orthokeratology (OK) lenses. All tests were performed monocularly on the right eye. The area under the log contrast sensitivity function (AULCSF) with DISC lenses was lower than that with SVL (1.14 vs. 1.40, p < 0.001) and HAL (1.14 vs. 1.33, p = 0.001). HAL increased the temporal visual field contrast threshold compared with OK lenses (p = 0.04), and OK lenses decreased the superior visual field contrast threshold compared with that of SVL (p = 0.04) and HAL (p = 0.005). HAL also increased the peripheral coherence threshold for identifying the contraction movement compared with OK lenses (p = 0.01). The short-term use of these optical interventions for myopia control exhibited measurable differences in central and peripheral visual performance. Relevant attention could be paid to these differences, especially when children switch to different treatments. DISC lenses exhibited worse central contrast sensitivity than SVL and HAL. Imposing peripheral defocus signals did not affect children's peripheral visual performance compared with SVL. However, considering the poorer peripheral visual performance provided by HAL, OK lenses are recommended for children if there are specific demands for global scene recognition and motion perception.

Spatial-temporal offshore wind speed characteristics prediction based on an improved purely 2D CNN approach in a large-scale perspective using reanalysis dataset

Accurate prediction of spatial–temporal wind speed with a large-scale perspective is vital for the wind farm dynamic regulation, the floating wind turbine deployment and its early warning. Machine-learning approaches have been applied for wind prediction to alleviate the computational challenges of traditional numerical models. Yet, most previous studies emphasized the forecasting accuracy employing location-specific dataset, such methodologies are site-specific and ignore the importance of spatial–temporal fidelity required by the 2D regional wind farm blueprint. Furtherly, the Recurrent Neural Networks based approach they employed exhibit low efficiency in terms of model convergence on the aspect of practical engineering purposes. This study firstly proposed an improved Unet-based machine learning method using residual learning to predict the spatial–temporal wind field in the North Atlantic Ocean with great potential wind-energy in a large spatial-scale perspective. Several state-of-the-art machine learning methods were established for a better performance comparison. A public reanalysis dataset with very high resolution (0.25° x 0.25°) was employed to verify the proposed method with multi-steps ahead predictions, the model performance was furtherly compared with the rest approaches under different criteria, consisting of Pearson correlation coefficient (PCC), Mean absolutely error (MAE), Root mean square error (RMSE) and symmetric mean absolute percentage error (SMAPE), all exhibiting considerable improvements. The overall forecasting RMSE for the proposed method dropped to 0.088 m/s and 0.087 m/s for wind component U and V correspondingly. Furtherly, comprehensive discussions were provided with both temporal and spatial perspective, revealing that the proposed model can offer an accurate 2D wind speed prediction along timeline (the PCC equals to 0.99). The proposed data-driven method presents promising potential to accurately preserve the spatial-resolved patterns which are variant in both spatial and temporal dimensions, and show superiority in terms of computational efficiency in terms of achieving large-scale wind pattern predictions.

Noninvasive Deep Brain Stimulation via Temporal Interference Electric Fields Enhanced Motor Performance of Mice and Its Neuroplasticity Mechanisms.

A noninvasive deep brain stimulation via temporal interference (TI) electric fields is a novel neuromodulation technology, but few advances about TI stimulation effectiveness and mechanisms have been reported. One hundred twenty-six mice were selected for the experiment by power analysis. In the present study, TI stimulation was proved to stimulate noninvasively primary motor cortex (M1) of mice, and 7-day TI stimulation with an envelope frequency of 20 Hz (∆f =20 Hz), instead of an envelope frequency of 10 Hz (∆f =10 Hz), could obviously improve mice motor performance. The mechanism of action may be related to enhancing the strength of synaptic connections, improving synaptic transmission efficiency, increasing dendritic spine density, promoting neurotransmitter release, and increasing the expression and activity of synapse-related proteins, such as brain-derived neurotrophic factor (BDNF), postsynaptic density protein-95 (PSD-95), and glutamate receptor protein. Furthermore, the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway and its upstream BDNF play an important role in the enhancement of locomotor performance in mice by TI stimulation. To our knowledge, it is the first report about TI stimulation promoting multiple motor performances and describing its mechanisms. TI stimulation might serve as a novel promising approach to enhance motor performance and treat dysfunction in deep brain regions.

Peripheral refraction under different levels of illuminance.

Peripheral refraction is believed to be involved in the development of myopia. The aim of this study was to compare the relative peripheral refraction (RPR) at four different levels of illuminance, ranging from photopic conditions to complete darkness, using an open-field autorefraction method. The RPRwas calculated for each eccentricity by subtracting central from peripheral autorefraction measurements. The study included 114 myopic eyes from 114 subjects (mean age of 21.81 ± 1.91 years) and the mean difference in RPRbetween scotopic and photopic conditions (0 and 300 lux, respectively) was +0.32 D at 30° temporal and +0.37 D at 30° in the nasal visual field (NVF). Statistically significant differences were observed between 0 and 300 lux at 30° in the temporal visual field and at 30° and 20° in the NVF. Our results revealed a significant increase in relative peripheral hyperopia with increasing visual field eccentricity along the horizontal visual field in myopic eyes of young adults. Furthermore, this relative peripheral hyperopia increased as illumination decreased. These findings suggest that an increase in peripheral illuminance may protect against myopic eye growth.

A detailed analysis of stochastic models applied to temporal gravity field recovery with GRACE observations

Summary In this study, we analyzed the impacts of errors in background force models and observed non-gravitational forces on the pseudo-observations (pre-fits) during gravity field recovery based on the GRACE satellite gravity mission. To reduce these effects, we introduced the stochastic parameters into the functional model of the variational equation integration approach to absorb this type of noise contribution. Simultaneously, the prior variances of observed orbits and K-Band range rates used in traditional method are re-estimated with least-square variance component estimation (LS-VCE) after considering these stochastic parameters. To improve the computing efficiency, a modified method of the calculation of sensitivity matrices related to the introduced stochastic parameters is proposed. Compared to the method of variation of constants widely used in the precise orbit determination and gravity field recovery, the modified method decreases the computational time of these matrices by about four times. Furthermore, an efficient LS-VCE algorithm is derived in a more generalized case. The efficient algorithm only costs 1% of the time of the unoptimized method. With the GRACE data, we analyzed the benefits of these refinements in gravity field recovery, and the results show that these improvements can mitigate the impacts of errors in background force models and accelerometer data on recovered gravity field models, especially in the high degree signals. Furthermore, the quality of results has less dependence on parameterization.

FRI318 A Case Of Mixed Growth Hormone And Prolactin-secreting Giant Pituitary Macroadenoma

Abstract Disclosure: A. Khan: None. I. Alpertunga: None. V. Kantorovich: None. Introduction Co-secretion of prolactin (PRL) and growth hormone (GH) from a single pituitary adenoma is an established entity in the medical literature and present in about 5% of the cases. Guidelines recommend to obtain an insulin-like growth factor-1 (IGF-1) in patients with prolactinoma at the time of initial diagnosis. Our case describes the management of a giant pituitary macroadenoma co-secreting PRL and GH. Case A 20-year-old male with history significant for schizophrenia presented with visual disturbances and discharge from his left nipple. His prolactin level (PRL) was noted to be elevated at 12,396 (4.0-15.2) ng/ml on work-up during recent prior investigation. On physical exam, he had bilateral temporal visual field deficit as well as dysfunction in upward gaze of left eye. Head imaging showed a 7.5 x 6.2 x 5 cm associated with remodeling of the sella turcica and expanding into the suprasellar space and significant mass-effect on the adjacent frontal lobes bilaterally, mild mass-effect on the adjacent optic chiasm with significant surrounding vasogenic edema and compressing the bilateral anterior cerebral arteries. Patient was started on low dose cabergoline in caution of prevention of possibility of rapid response-related significant volume contraction of the tumor with possibility of reactive edema. The dose of cabergoline was rapidly titrated up to 3 mg bi-weekly with minimal prolactin fluctuation of PRL between 12,000 and 16,000 ng/ml. Because of mild atypical acromegalic facial features, patient had GH axis assessment. IGF-1 level came back elevated at 529 (83-456) ng/ml with a high IGF Binding Protein- 3 of 8.9 (2.9-7.2) mg/l. He was started on octreotide titrated up to a dose of 150 mcg three times daily. Repeat MRI brain did not show tumor shrinkage. Subsequently, patient underwent bifrontal craniotomy for resection/debulking of parasellar tumor. PRL dropped to 931 ng/ml immediately after surgery. At the time of writing, pathology of the tumor and repeat IGF-1 level is pending. Patient was monitored closely in the ICU with a steroid taper postoperatively. Discussion Dopamine agonists are the first-line therapy for medical treatment of hyperprolactinemia but can also suppress GH and IGF-1 levels. However, in acromegaly, cabergoline is utilized mostly for small adenomas with mild elevation of IGF-1. In our case, we decided to use a combination of cabergoline and somatostatin receptor analog, octreotide. However, given the giant adenoma with very high PRL and IGF-1 levels, patient showed a poor response to medical therapy, and given the impending threat to patient’s vision, he underwent surgical debulking. Our case highlights the management of a giant, mixed hormone-secreting pituitary adenoma. Presentation: Friday, June 16, 2023

FRI310 Massive Gonadotropin-Secreting Adenoma In A Young Man: A Challenging Differential Diagnosis Of A Sellar Mass

Abstract Disclosure: C. Nava Suarez: None. J. Prater: None. N. Blocher: None. S. Sathi: None. Introduction: Gonadotropin-secreting adenomas are usually nonfunctioning representing 90% of silent pituitary masses. However, functioning gonadotropin-secreting adenomas (FGA) are rare, with unknown incidence given their infrequent recognition. FGA usually presents with high FSH and variable sex hormone levels. Usually misdiagnosed, these tumors present with late mass effect symptoms. Neuroimaging usually shows a sellar mass with extrasellar extension and compression of nearby structures. We present a case of a man with a massive FGA with craniopharyngioma features on imaging. Case: A 33-year-old male with left eye blindness for 3 years presented for evaluation of acute headache and right eye blurriness but no other symptoms. Ophthalmologic evaluation demonstrated left optic atrophy, right optic disc edema, and temporal field cut from optic chiasm involvement. Hormonal workup showed a markedly elevated FSH at 36.8 mIU/ml (&amp;lt;12 mIU/ml), normal total testosterone at 835 ng/dL (250-1000 ng/dL), and mildly elevated prolactin at 28.6 ng/dL (&amp;lt;29.4 ng/dL), all other pituitary hormones were normal. Brain MRI demonstrated a multilobulated, heterogeneously enhancing solid-cystic mass in the sellar and suprasellar area. It was T1 iso-hypointense, T2/FLAIR isointense, and had a few calcifications. There was mass effect on the optic chiasm, left frontal and temporal lobes, and left lateral ventricle causing obstructive hydrocephalus. Craniopharyngioma was the initial diagnosis given radiographic features. The patient required an extended left frontotemporal craniotomy for tumor debulking. Pathology reported pituitary macroadenoma with positive FSH immunostaining. He is planned for radiation therapy given the presence of residual tumor. Discussion: This case illustrates the late presentation of gonadotrophin pituitary adenoma. Up to 90% of silent pituitary adenomas stain for FSH or LH, but are not clinically active. A minority of these secrete functioning hormones which can result in clinically relevant effects with FSH elevation more commonly seen than LH elevation. In our case one would have expected low testosterone in the setting of high FSH as seen in primary hypogonadism, but testosterone levels can range from low to high in FGA. Men usually complain of erectile dysfunction and decreased libido. Our case is particularly interesting because of the imaging features (mixed cystic-solid components with calcifications) suggestive of craniopharyngioma. Radiologic features have over 90% accuracy in distinguishing craniopharyngioma from pituitary adenomas. An accurate pre-operatively diagnosis is important as it may affect the surgical approach and prognosis. Clinicians should have a high level of suspicion for FGA in patients with neurological and visual symptoms, especially when associated with sexual dysfunction, although the last is not always present. Presentation: Friday, June 16, 2023

THU104 An Atypical Case Of A Suprasellar Cyst: A Diagnostic Challenge

Abstract Disclosure: A. Chen: None. S. Zachariah: None. B. Wong: None. E. Owusu: None. A. Levitt: None. R. Todor: None. P. Kishore: None. Background: Cystic sellar masses may be challenging to diagnose on a clinical, imaging, and histopathological basis due to overlapping features. We report a case of a cystic sellar mass in which traditional imaging findings did not correspond to its histopathological findings. Clinical Case: A 37-year-old female presented with headaches and bilateral blurry vision for two months with acute worsening of left peripheral vision for one week. She denied irregular periods, hirsutism, or breast discharge. Ophthalmology evaluation found left temporal field vision loss but normal maculae/optic nerves. MRI pituitary exhibited 2.3 x 1.5 x 1.7 cm complex cystic suprasellar mass with partial rim enhancement, thought to represent a cystic macroadenoma. Initial tests were notable for negative HCG, prolactin 96.32 mIU/mL (n &amp;lt; 23.3 mIU/mL), TSH 9.440 uIU/mL (0.270-4.2 uIU/mL), normalized to 0.855 uIU/mL on repeat testing, FT4 0.748 ng/dL (n = 0.75 – 2.0 ng/dL). IGF-1, ACTH, AM cortisol, FSH, and LH were within normal limits. She was started on cabergoline prior to trans-nasal-sphenoid resection with cyst drainage of white and thick content. Histopathology exhibited a squamous epithelium-lined cyst with no columnar epithelium or mucin-containing cells, consistent with an epidermoid cyst (EC), although the differential included a Rathke’s cleft cyst (RCC). No pituitary tumor was noted. A re-evaluation of MRI in multidisciplinary rounds deemed epidermoid cyst unlikely, given that these present with restricted diffusion. Our patient had overall T2 hyperintensity with an associated T2 hypointense nodule and did not restrict diffusion [1]. After interdisciplinary discussion, including imaging and pathology review, it was felt that the most likely diagnosis was RCC with squamous metaplasia. After surgery, the patient's symptoms and visual function completely recovered, and follow-up imaging is scheduled. Conclusion: Differentiating RCC with squamous metaplasia from EC can be challenging since both may present with a squamous epithelial lining [2]. Rates of progression and recurrence vary amongst cysts; therefore, making an accurate diagnosis is essential for selecting management, predicting the likelihood of recurrence, and guiding postoperative surveillance. This case is unique in that radiologic features were more helpful than histopathology in determining the diagnosis and highlights the importance of collectively considering clinical, imaging, and histopathological features in making a final diagnosis.

Tracking of Gaussian pulse release length inside mode-locked semiconductor laser amplifier

The behavior of the optical pulse release was investigated during chirped pulses amplification, which consisted of two chirped fiber Bragg grating and one semiconductor optical amplifier (SOA). This occurred when the pulse width, &amp;lt;&amp;lt; carrier lifetime , as well as the effect of the length parameter on the shape and spectrum of the electric field, intensity, and phase of amplified pulses, were taken into consideration. The purpose of this research is to investigate the effect of release length on the temporal electric field laser amplifier while simultaneously generating optical pulses with the help of a mode-locked laser system semiconductor. In the scenario where τp and τc are taken into account, we discovered that the length of the release has a significant impact on the modes of the phase and the electric field.

A versatile 4K insert for characterization of the superconducting joints.

A multi-coil superconducting magnet is the heart of any modern Magnetic Resonance Imaging (MRI) scanner. The superconducting magnet in MRI produces a highly homogeneous field (±5 ppm) and stable field (<0.1 ppm/h) in its imaging volume. The temporal field stability depends on the electrical resistance of the inter-coil joints and the electrical resistance of the joint between the coil and the superconducting switch. To establish the joint technology, a 4K test rig is required for testing the sample joints. This paper briefly discusses the details of the versatile 4K insert recently developed at IUAC for the characterization of the superconducting joints using the field-decay measurement technique. It can measure the joint resistance up to ∼10-15 Ω in a straight or spiral joint configuration with lengths up to 150mm. The maximum current that can be induced on the test coil is more than 600A for the field-decay measurement. The behavior of the joint resistance can also be studied in the presence of a 1.5T background field. We have characterized many superconducting joints using this versatile 4K insert. The joints between two different conductors can also be studied using this 4K insert. The lowest joint resistance measured is 8 × 10-15 Ω at zero field. The joint resistance is also measured in the presence of the background field.

Measuring and modeling investigation of the net photochemical ozone production rate via an improved dual-channel reaction chamber technique

Abstract. Current process-based research mainly uses box models to evaluate photochemical ozone production and destruction rates, and it is unclear to what extent the photochemical reaction mechanisms are elucidated. Here, we modified and improved a net photochemical ozone production rate (NPOPR, P(O3)net) detection system based on the current dual-channel reaction chamber technique, which makes the instrument applicable to different ambient environments, and its various operating indicators were characterized, i.e., “airtightness”, light transmittance, wall losses of the reaction and reference chambers, conversion rate of O3 to NO2, air residence time, and performance of the reaction and reference chambers. The limits of detection of the NPOPR detection system were determined to be 0.07, 1.4, and 2.3 ppbv h−1 at sampling flow rates of 1.3, 3, and 5 L min−1, respectively. We further applied the NPOPR detection system to field observations at an urban site in the Pearl River Delta (China). During the observation period, the maximum value of P(O3)net was 34.1 ppbv h−1, which was ∼ 0 ppbv h−1 at night within the system detection error and peaked at approximately noon local time. The daytime (from 06:00–18:00 LT) average value of P(O3)net was 12.8 (± 5.5) ppbv h−1. We investigated the detailed photochemical O3 formation mechanism in the reaction and reference chambers of the NPOPR detection system using a zero-dimensional box model. We found that the photochemical reactions in the reaction chamber were very close to those in ambient air, but there was not zero chemistry in the reference chamber because the reaction related to the production and destruction of RO2 (= HO2 + RO2) continued in the reference chamber, which led to a small amount of P(O3)net. Therefore, the P(O3)net measured here can be regarded as the lower limit of the real P(O3)net in the atmosphere; however, the measured P(O3)net was still ∼ 7.5 to 9.3 ppbv h−1 higher than the modeled P(O3)net value depending on different modeling methods, which may be due to the inaccurate estimation of HO2 / RO2 radicals in the modeling study. Short-lived intermediate measurements coupled with direct P(O3)net measurements are needed in the future to better understand O3 photochemistry. Our results show that the NPOPR detection system can achieve high temporal resolution and continuous field observations, which helps us to better understand photochemical O3 formation and provides a key scientific basis for continuous improvement of air quality in China.

Visual field after anti-vascular endothelial growth factor therapy and laser treatment for retinopathy of prematurity.

To evaluate the visual field after anti-vascular endothelial growth factor (VEGF) therapy and laser treatment for retinopathy of prematurity. Retrospective cohort study. Infants with retinopathy of prematurity treated by anti-VEGF therapy or laser treatment were included in the study. Degrees of visual field in eight directions examined by Goldmann perimeter (intensity, 1000 apostilb; size, V4e = 64 mm2) were compared between the anti-VEGF therapy and laser treatment groups. The visual acuity (VA) and spherical equivalent refraction were also compared between the two groups. Nine eyes with anti-VEGF therapy and 12 eyes with laser treatment were enrolled in the analysis. The total, upper, nasal upper, nasal, nasal lower, temporal lower, and temporal upper visual fields were significantly wider in the eyes with anti-VEGF therapy than in those with laser treatment (496 vs 416, P = .002; 53 vs 45, P = .008; 56 vs 43, P = .003; 58 vs 39, P < .001; 55 vs 44, P = .01; 72 vs 65, P = .01; and 62 vs 56, P = .03, respectively). The logarithm of the minimum angle of resolution VA tended to be better in the eyes with anti-VEGF therapy than in those with laser treatment (0.01 vs 0.15, P = .06). Eyes with anti-VEGF therapy had significantly lower myopia than those with laser treatment (spherical equivalent refraction: -0.72 vs -5.7, P = .001). Anti-VEGF therapy may provide a wider visual field, better VA, and less myopia compared with laser treatment.

A graphics-accelerated deep neural network approach for turbomachinery flows based on large eddy simulation

In turbomachinery, strongly unsteady rotor–stator interaction triggers complex three-dimensional turbulent flow phenomena such as flow separation and vortex dynamics. Large eddy simulation (LES) is an advanced numerical method that has recently been used to resolve large-scale turbulent motions and model subgrid-scale turbulence in turbomachinery. To largely reduce the computing cost of LES for turbomachinery flow, a graphics processing unit (GPU)-accelerated deep neural network-based flow field prediction approach is explored, which combines convolutional neural network autoencoder (CNN-AE) with long short-term memory (LSTM). CNN-AE extracts spatial features of turbomachinery flow by mapping high-dimensional flow fields into low-dimensional space, while LSTM is used to predict the temporal evolution of fluid dynamics. Automatic mixed precision (AMP) is employed to achieve rapid neural network training using Nvidia GTX 1080 Ti GPU, which shows a significant speedup compared with that without AMP. We evaluated the proposed CNN-AE-LSTM (CAL) method against gated recurrent units (GRU) and simple recurrent network (SRN) on two types of turbomachinery, i.e., centrifugal and axial flow pumps. The results show that the proposed CAL shows better capability of capturing the vortex structure details of turbomachinery. When predicting the temporal vorticity field, the mean square error of CAL results is 0.105%–0.124% for centrifugal pumps and 0.071%–0.072% for axial flow pumps. Meanwhile, the structural similarity index measure of the CAL results is 92.51%–92.77% for centrifugal pumps and 93.81%–94.61% for axial flow pumps. The proposed CAL is noticeably better than GRU and SRN in terms of both mean square error and structural similarity index measure.

A Novel Computationally Efficient Approach for Exploring Neural Entrainment to Continuous Speech Stimuli Incorporating Cross-Correlation

A linear system identification technique has been widely used to track neural entrainment in response to continuous speech stimuli. Although the approach of the standard regularization method using ridge regression provides a straightforward solution to estimate and interpret neural responses to continuous speech stimuli, inconsistent results and costly computational processes can arise due to the need for parameter tuning. We developed a novel approach to the system identification method called the detrended cross-correlation function, which aims to map stimulus features to neural responses using the reverse correlation and derivative of convolution. This non-parametric (i.e., no need for parametric tuning) approach can maintain consistent results. Moreover, it provides a computationally efficient training process compared to the conventional method of ridge regression. The detrended cross-correlation function correctly captures the temporal response function to speech envelope and the spectral–temporal receptive field to speech spectrogram in univariate and multivariate forward models, respectively. The suggested model also provides more efficient computation compared to the ridge regression to process electroencephalography (EEG) signals. In conclusion, we suggest that the detrended cross-correlation function can be comparably used to investigate continuous speech- (or sound-) evoked EEG signals.

A New GRACE Filtering Approach Based on Iterative Image Convolution

AbstractThe Gravity Recovery and Climate Experiment (GRACE) mission and its successor GRACE Follow‐On (GRACE‐FO) mission provide humans with a unique perspective on mass distribution through accurate temporal gravity field models. However, these models suffer from unavoidable stripe errors in the spatial domain. A new approach based on image processing has been developed for filtering GRACE and GRACE‐FO spherical harmonic solutions. In this approach, the gravity fields are treated as noise‐contaminated images, and the stripe errors are expected to be suppressed by convolving the input with an appropriate kernel. To verify the effectiveness of the proposed approach, a closed‐loop simulation environment over the nominal mission lifetime of 5 years is designed. Image processing indicators and geophysical information evaluation results demonstrate the superior performance of the new approach in suppressing stripe errors. In the context of real GRACE data processing, our new approach still yields better results as follows: (a) The comprehensive ability of de‐striping and retaining details has slight advantages over some commonly used filters, as demonstrated through spatial distributions, amplitude spectra, and coefficient spectra. (b) The equivalent water height time series at the basin scale is comparable to the results derived from other filters or Level‐3 products. (c) The estimated signal amplitude of the Mw9.1 2004 Sumatra earthquake co‐seismic gravity change is 52.7% larger than that derived from the Gaussian 300 km filter, which is much closer to the theoretical value derived from the dislocation theory.

Electromagnetic characteristics of NI-REBCO coils according to contact surface conditions controlled by the oxidation state and roughness of the REBCO conductor

Although no-insulation (NI) rare-earth barium copper oxide (REBCO) coils offer technical advantages, such as high-energy density, mechanical strength, and self-stabilizing performance, sometimes their applications are limited owing to current leaks through turn-to-turns inside the coils, which are caused by their very low turn-to-turn contact resistance. This results in temporal magnetic field delays and limits their applicability in fields requiring fast response performance in magnetic field control. These shortcomings can be addressed by increasing the turn-to-turn contact resistance of the NI coils. A NI winding method with REBCO conductor variations of surface-oxidation and roughness was proposed in this study; this method improved the magnetic field response by reducing the temporal delays of the magnetic field via the suppression of the turn-to-turn bypass current. This was achieved by increasing the turn-to-turn contact resistance within the NI coils through adjustments to the oxidation and roughness of the surface of a copper stabilizer layer, which was coated on the outermost part of the REBCO conductor by electroplating to ensure electrical and mechanical protection. In this study, the steady- and transient-state characteristics of NI coils were experimentally analyzed according to changes in the oxidation and roughness levels of the surface of the REBCO conductor. To verify the effectiveness of the proposed winding approach, basic tests were conducted in a liquid nitrogen cooling environment by constructing different types of sample coils using REBCO conductors, which were thermally oxidized at different temperatures in a convection oven and scratched using sandpaper. Further, the decay time constant and the time delay of the center magnetic field in the sample coils were measured in sudden current discharging and current charging/discharging tests, respectively. In addition, overcurrent tests using currents exceeding the critical current were conducted to analyze the thermal stability of the sample coils. In conclusion, it was experimentally verified that the time delays of the NI coils were reduced as the surface oxidation and roughness of the REBCO conductor increased. Furthermore, when the oxidizing and scratching approaches were employed, the contact resistance values of the NI coils (3.48 µΩ·cm2), which were not subjected to any surface treatment, increased to 155.01 and 4.43 µΩ·cm2, which were oxidized at 230 °C and sanded using P400-grit sandpaper, respectively. For oxidizing approach, heat treat temperatures at 200 °C – 230 °C will be suitable for increasing the contact resistance of NI coils without inserting any resistive material, thus resulting in a enhancing the magnetic response performance of NI coils.

Experimental and numerical analyses of gravity-driven granular flows between vertical parallel plates for solar thermal energy storage and transport

Gravity-driven granular flows between vertical parallel plates were considered at elevated temperatures to examine flow behavior and inform solar thermal energy storage and transport infrastructure design and performance. A series of experiments was performed at inlet temperatures of 23, 200, 400, 600, and 800 °C in a high-temperature granular flow experimental rig and spatial and temporal velocity and surface temperature fields were measured. Granular flows were observed to change as a function of temperature. The interaction between the particles and the wall significantly increased with decreases in channel widths. Particle velocities at the outlet of the channel were compared with results from numerical model using the discrete element method. Temperature-dependent flow properties directly related to the assembly were measured and used for granular flow simulation. Flow behavior within the channel was investigated from the simulated results by obtaining particle volume fractions and particle velocities. Wall temperature and outlet granular flow temperature were monitored during the flow experiment and temporal heat loss in the flow was calculated. The granular flow behavior and heat transfer analysis from both the experiment work and simulation provide important mass transfer information for heat transfer modeling at elevated temperature.