Source Conditions Research Articles

Reconstructing the source condition for focused shear wave beams in soft elastic media

Shear waves are employed in medical ultrasound imaging because they reveal variations in viscoelastic properties of soft tissue. Focused shear waves produced by a longitudinally vibrating piston at several hundred hertz are investigated here experimentally in soft tissue phantoms and using an analytical model for shear wave beam generation and propagation. Experiments employed a spherically concave piston shaped to focus the shear wave beam at a depth of 4 cm in a soft tissue phantom. Analytical modeling of this data provided a good fit, but required treating the focal length and piston diameter as adjustable parameters. The largest source of error in the modeling is suspected to be that the source condition is assumed to exhibit zero displacement surrounding the piston, whereas the actual condition in the source plane is a traction-free surface surrounding the piston. Here, in order to elucidate the actual source condition, numerical back propagation of field measurements is employed. Simulations show that the shear source condition can be accurately recovered with information related only to the shear wave, i.e., without compressional wave information. Back propagation of measured beams is discussed in the context of more accurately modeling the source condition for future device optimization.

Protection exhibited by hearing protection devices using test fixtures under extended shock tube exposure ranges

Hearing protection devices (HPDs) are used in a variety of environments to mitigate the risk of hearing injury, particularly in environments with pervasive impulsive noise. Evaluation of HPD performance for these conditions can be performed with acoustic test fixtures to ensure human subjects are not exposed to injurious levels of noise. Impulse Peak Insertion Loss (IPIL) and Impulse Spectral Insertion Loss (ISIL), as defined in ASA/ANSI S12.42, are used to quantify and compare performance of HPDs in exposure environments created by different impulsive sources. To simulate a range of exposures relevant across industries, multiple shock tubes were used to generate waveforms with A-durations ranging from 0.1 to 6.0 ms and peak pressures ranging from 130 to 183 dB. Protection provided by each device varied depending on the source conditions with passive and active devices producing fundamentally different responses depending on source characteristics. Ultimately, evaluation of devices under a variety of impulsive noise conditions allows for a more representative evaluation of HPD performance, bridging the gap between standard testing protocols and real-world acoustic environments, thus enabling better informed HPD selection.

Experimental Study of the Injectability of Infiltration Grouting in Surface Moraine of Pulang Copper Mine

In order to effectively reduce the risk of underground debris flow, surface moraine is solidified and modified by using grouting technology to realize the change in fine-grained moraine from “powder” to “block” to change the source conditions of underground debris flow and to reduce the risk of moraine from the root. In this paper, the effects of grouting pressure, porosity, and pore diameter on the spillability of moraine are investigated experimentally. The results show that the grouting depth increases linearly with increasing sample porosity. For the same sample density, the grouting pressure is proportional to the grouting depth. As the pore diameter of the sample increases, the longitudinal grouting depth of the sample increases, but the transverse diffusion distance decreases. The chemical grout in the moraine is mainly split-infiltration grouting mode. The present research results can provide effective support for the prevention and control of underground debris flow in Pulang Copper Mine.

ISSLS PRIZE in Basic Science 2024: superiority of nucleus pulposus cell- versus mesenchymal stromal cell-derived extracellular vesicles in attenuating disc degeneration and alleviating pain

PurposeTo investigate the therapeutic potential of extracellular vesicles (EVs) derived from human nucleus pulposus cells (NPCs), with a specific emphasis on Tie2-enhanced NPCs, compared to EVs derived from human bone marrow-derived mesenchymal stromal cells (BM-MSCs) in a coccygeal intervertebral disc degeneration (IDD) rat model.MethodsEVs were isolated from healthy human NPCs cultured under standard (NPCSTD-EVs) and Tie2-enhancing (NPCTie2+-EVs) conditions. EVs were characterized, and their potential was assessed in vitro on degenerative NPCs in terms of cell proliferation and senescence, with or without 10 ng/mL interleukin (IL)-1β. Thereafter, 16 Sprague–Dawley rats underwent annular puncture of three contiguous coccygeal discs to develop IDD. Phosphate-buffered saline, NPCSTD-EVs, NPCTie2+-EVs, or BM-MSC-derived EVs were injected into injured discs, and animals were followed for 12 weeks until sacrifice. Behavioral tests, radiographic disc height index (DHI) measurements, evaluation of pain biomarkers, and histological analyses were performed to assess the outcomes of injected EVs.ResultsNPC-derived EVs exhibited the typical exosomal morphology and were efficiently internalized by degenerative NPCs, enhancing cell proliferation, and reducing senescence. In vivo, a single injection of NPC-derived EVs preserved DHI, attenuated degenerative changes, and notably reduced mechanical hypersensitivity. MSC-derived EVs showed marginal improvements over sham controls across all measured outcomes.ConclusionOur results underscore the regenerative potential of young NPC-derived EVs, particularly NPCTie2+-EVs, surpassing MSC-derived counterparts. These findings raise questions about the validity of MSCs as both EV sources and cellular therapeutics against IDD. The study emphasizes the critical influence of cell type, source, and culture conditions in EV-based therapeutics.

Review of Organic Rankine Cycles for Internal Combustion Engine Waste Heat Recovery: Latest Decade in Review

The last decade (2013–2023) was the most prolific period of organic Rankine cycle (ORC) research in history in terms of both publications and citations. This article provides a detailed review of the broad and voluminous collection of recent internal combustion engine (ICE) waste heat recovery (WHR) studies, serving as a necessary follow-on to the author’s 2013 review. Research efforts have targeted diverse applications (e.g., vehicular, stationary, and building-based), and it spans the full gamut of engine sizes and fuels. Furthermore, cycle configurations extend far beyond basic ORC and regenerative ORC, particularly with supercritical, trilateral, and multi-loop ORCs. Significant attention has been garnered by fourth-generation refrigerants like HFOs (hydrofluoroolefins), HFEs (hydrofluoroethers), natural refrigerants, and zeotropic mixtures, as research has migrated away from the popular HFC-245fa (hydrofluorocarbon). Performance-wise, the period was marked by a growing recognition of the diminished performance of physical systems under dynamic source conditions, especially compared to steady-state simulations. Through advancements in system control, especially using improved model predictive controllers, dynamics-based losses have been significantly reduced. Regarding practically minded investigations, research efforts have ameliorated working fluid flammability risks, limited thermal degradation, and pursued cost savings. State-of-the-art system designs and operational targets have emerged through increasingly sophisticated optimization efforts, with some studies leveraging “big data” and artificial intelligence. Major programs like SuperTruck II have further established the ongoing challenges of simultaneously meeting cost, size, and performance goals; however, off-the-shelf organic Rankine cycle systems are available today for engine waste heat recovery, signaling initial market penetration. Continuing forward, next-generation engines can be designed specifically as topping cycles for an organic Rankine (bottoming) cycle, with both power sources integrated into advanced hybrid drivetrains.

Non-Abelian physics in light and sound.

Non-Abelian phenomena arise when the sequence of operations on physical systems influences their behaviors. By possessing internal degrees of freedom such as polarization, light and sound can be subjected to various manipulations, including constituent materials, structured environments, and tailored source conditions. These manipulations enable the creation of a great variety of Hamiltonians, through which rich non-Abelian phenomena can be explored and observed. Recent developments have constituted a versatile testbed for exploring non-Abelian physics at the intersection of atomic, molecular, and optical physics; condensed matter physics; and mathematical physics. These fundamental endeavors could enable photonic and acoustic devices with multiplexing functionalities. Our review aims to provide a timely and comprehensive account of this emerging topic. Starting from the foundation of matrix-valued geometric phases, we address non-Abelian topological charges, non-Abelian gauge fields, non-Abelian braiding, non-Hermitian non-Abelian phenomena, and their realizations with photonics and acoustics and conclude with future prospects.

A Theoretical Study on the Thermal Performance of an Increasing Pressure Endothermic Cycle for Geothermal Power Generation

In this study, a power cycle (IPEC), with an increasing pressure endothermic process in a downhole heat exchanger (DHE) and a CO2-based working fluid mixture, was developed for geothermal power generation. The increasing pressure endothermic process, which cannot be achieved in a conventional evaporator on the ground, was realized using the gravitational potential energy in the DHE. The parameters of the power cycle and the structural size of the DHE were optimized simultaneously. Using CO2-R32 as the working fluid of the IPEC provides the highest net power output. The net power generated with the IPEC was compared with a single-flash (SF) system, a trans-critical CO2 (t-CO2) system, and an organic Rankine cycle (ORC) under the same heat source and sink conditions. Six selection maps were generated for choosing the optimum power cycle for electricity production, in which four power generation systems (ORC, t-CO2, IPEC, and SF) were included, and two DHE diameters (0.155 m and 0.22 m) were investigated. It was found that the IPEC system had more net power output than the other three systems (ORC, t-CO2, and SF) under the conditions that the geofluid’s mass flow rate was less than 10 kg/s and its temperature was lower than 180 °C.

Novel Method on Mixing Degree Quantification of Mine Water Sources: A Case Study

After a mine water inrush occurs, it is crucial to quickly identify the source of the water inrush and the key control area, and to formulate accurately efficient water control measures. According to the differences in water chemical characteristics of four aquifers in the Fenyuan coal mine, the concentrations of K+~Na+, Ca2+, Mg2+, Cl−, SO42−, and HCO3− were taken as water source identification indexes. A decision tree classification model based on the C4.5 algorithm was adopted to visualize the chemical characteristics of a single water source and extract rules, and intuitively obtained the discrimination conditions of a single water source with Mg2+, Ca2+, and Cl− as important variables in the decision tree: Mg2+ < 39.585 mg/L, Cl− < 516.338 mg/L and Mg2+ ≥ 39.585 mg/L, Ca2+ < 160.860 mg/L. Factor analysis and Fisher discriminant theory were used to eliminate the redundant ion variables, and the discriminant function equations of the two, three, and four types of mixed water sources were obtained successively in turn. This paper puts forward MSE, RMSE, and MAE as the evaluation indexes of the water source mixing degree calculation models and obtains the ranking of the pros and cons of the mixed water source mixing degree calculation models. The results show that the minimum inscribed circle analytical method is the optimal model for the calculation of the mixing degree of two types of water sources, and the MSE, RMSE, and MAE are 0.17%, 4.13%, and 4.13%, respectively. The minimum inscribed circle clustering method is the optimal model for the calculation of the mixing degree of three types of water sources, and the minimum distance method is the optimal model for the calculation of the mixing degree of four types of water sources. The method of mine water source identification based on the decision tree C4.5 algorithm and mixing degree calculation has the characteristics of a simple calculation process, high efficiency, objective accuracy, and low cost, which can provide a scientific basis for the development of stope water control measures.

Remarkable reduction in thermal contact resistance between target and heat exchanger using TIMs in isotope neutron source accelerator

The high thermal contact resistance (TCR) between the target and the heat exchanger in the Isotope Neutron Source Accelerator will cause the high-energy charged particle beam to stay in the target, resulting in a remarkable increase of temperature which affects the production of stable isotopes. At present, the usage of thermal interface materials (TIMs) can fill the gap at the contact surface and thus reduces the TCR. In this paper, aiming at the actual working condition of neutron source, the steady-state TCR measurement experiment is designed under vacuum and high temperature environment. The TCR at the contact surface was reduced after adding graphite films, thermal greases, liquid metals and preloads. The improvement of TCR of the contact surface between palladium (Pd), copper (Cu) and graphite (Gr) were measured respectively. The results show that the TCR between palladium and graphite is reduced by 95 % by adding liquid metal (Gallium alloy). The TCR between copper and graphite was reduced by 91 % by brazing method. Compared with other TIMs, graphite film has the advantages of high thermal conductivity, high temperature resistance and no fluidity. Adding 0.08 mm thick graphite film between Pd/Gr and Cu/Gr contact surface can reduce the TCR by 50 % and 70 %, respectively. The improvement effect between the two contact surfaces was not obvious when 15.9–318.3 kPa preload was applied.

Uncertainty Quantification of Neural Reflectance Fields for Underwater Scenes

Neural radiance fields and neural reflectance fields are novel deep learning methods for generating novel views of 3D scenes from 2D images. To extend the neural scene representation techniques to complex underwater environments, beyond neural reflectance fields underwater (BNU) was proposed, which considers the relighting conditions of on-aboard light sources by using neural reflectance fields, and approximates the attenuation and backscatter effects of water with an additional constant. Because the quality of the neural representation of underwater scenes is critical to downstream tasks such as marine surveying and mapping, the model reliability should be considered and evaluated. However, current neural reflectance models lack the ability of quantifying the uncertainty of underwater scenes that are not directly observed during training, which hinders their widespread use in the field of underwater unmanned autonomous navigation. To address this issue, we introduce an ensemble strategy to BNU that quantifies cognitive uncertainty in color space and unobserved regions with the expectation and variance of RGB values and termination probabilities along the ray. We also employ a regularization method to smooth the density of the underwater neural reflectance model. The effectiveness of the present method is demonstrated in numerical experiments.

Exploration of the microbial dust suppressant application in open-pit coal mines: Dust source conditions and application processes

To promote large-scale application, this paper studied the influences of different dust source conditions and application processes on microbial dust suppressant. Results showed that microbial dust suppressant could adapt to various dust source conditions. The wind erosion rate of samples did not exceed 47 g·m−2·min−1 after a single spraying volume of more than 1.25 L·m−2 and more than 4 spraying times. The change of CaCO3 crystallinity (about 6%) and crystal forms led to the change of hardness and thickness of the cemented layer (about 12–24%). The crystallization process of microbial dust suppressant is an important factor affecting performance, which is mainly regulated by saturation. In addition, the contact distribution mode of CaCO3 between particles and its corresponding pore was put forward. CaCO3 deposited by surface contact was the key to improving dust suppression performance. Under the background of large-scale application, 1.25 L·m−2 and 2 times for spraying were more suitable.

Configuration of Organic Rankine Cycles for Geothermal Applications: An Industrial Perspective

Abstract Geothermal resources represent a valuable option to reduce fossil fuel-based power production because they feature an unmatched capacity factor among other renewable energy sources (RES). Geothermal resource availability reduces with the temperature. Therefore, developing cost-effective solutions to exploit low-temperature geothermal energy is mandatory to expand technology utilization. The standard solution for converting low-temperature thermal sources into power is organic rankine cycles (ORCs). ORC basic layout (subcritical) is well-known, but the more advanced alternatives, such as transcritical and two-pressure level cycles, are much less widespread, and it is unclear whether the higher efficiency justifies the higher capital cost. The paper focuses on the exploitation with ORC of geothermal resources (hot water) with a temperature lower than 200 °C and mass flow rates between 200 and 1400 m3/h for a target power production ranging from 3 to 30 MW. The paper compares three ORC layouts, subcritical, transcritical, and two pressure-level, from thermodynamic and economic points of view to map the most cost-effective solutions in the investigated size ranges. The techno-economic comparison considers the impact of the operating conditions and fluid on the machine's expected performance and the heat exchangers' size. As expected, more complicated layouts yield higher conversion efficiencies, with the two pressure-level cycles achieving the highest power output for the same geothermal source conditions. However, the economic analysis showed that the most efficient solutions are not always preferable when considering the cost-efficiency tradeoff.

Changing Attitudes About a Pro-Environmental Proposal Concerning Solar Power: The Self-Validating Role of Ingroup Versus Outgroup Sources.

In this study, we examined whether a persuasive message in favor of a pro-environmental proposal could influence attitude change through a self-validation process when individuals were told that the source of the proposal belonged to their ingroup (vs. their outgroup). Participants read a message that advocated for the use of solar power. Immediately following the message, participants were asked to list their thoughts regarding the persuasive proposal. A thought favorability index was created for each participant. Following the thought-listing task, participants received the experimental manipulation (i.e., ingroup vs. outgroup source) based on the minimal group paradigm, after which they reported their attitudes towards the proposal. A regression analysis showed the predicted interaction between thought favorability and type of source (i.e., ingroup vs. outgroup) on attitudes towards the solar power proposal. According to our expectations, thought favorability was a better predictor of attitudes for participants in the ingroup (vs. outgroup) source condition. Attitudes can be polarized as a function of ingroup versus outgroup differentiation through a self-validation process.

Performance analysis of multiview video compression based on MIV and VVC multilayer

AbstractTo represent immersive media providing six degree‐of‐freedom experience, moving picture experts group (MPEG) immersive video (MIV) was developed to compress multiview videos. Meanwhile, the state‐of‐the‐art versatile video coding (VVC) also supports multilayer (ML) functionality, enabling the coding of multiview videos. In this study, we designed experimental conditions to assess the performance of these two state‐of‐the‐art standards in terms of objective and subjective quality. We observe that their performances are highly dependent on the conditions of the input source, such as the camera arrangement and the ratio of input views to all views. VVC‐ML is efficient when the input source is captured by a planar camera arrangement and many input views are used. Conversely, MIV outperforms VVC‐ML when the camera arrangement is non‐planar and the ratio of input views to all views is low. In terms of the subjective quality of the synthesized view, VVC‐ML causes severe rendering artifacts such as holes when occluded regions exist among the input views, whereas MIV reconstructs the occluded regions correctly but induces rendering artifacts with rectangular shapes at low bitrates.

Energy loss evaluation in radical inflow turbine based on entropy production theory and orthogonal experiment method

The fluctuation of heat source conditions results in off-design operation of the radial inflow turbines (RIT) in the organic Rankine cycle. However, the flow loss characteristics of RIT under off-design conditions have not been completely revealed. The entropy production theory has the advantage of determining the quantity and location of energy dissipation, which is used to evaluate the energy loss of RIT under different conditions. In addition, the order of operating parameters on the RIT energy loss is determined by the orthogonal experimental method. The results show that each entropy production term and the entropy production of different components increase with the increase in the inlet pressure and inlet temperature, while they decrease with the increase in the outlet pressure of the RIT. Under different operating conditions, the turbulent dissipation and wall dissipation are the main cause of RIT energy loss, which are closely related to vortices and high velocity gradients in the flow field. The rotor and diffuser contribute the main energy loss of RIT. However, the volume-average entropy production and area-average entropy production of the stator and rotor are higher than those of other components. In addition, the wall shear is the main cause of the stator energy loss, while the turbulent dissipation dominants the rotor energy loss. The outlet pressure has the greatest impact on the turbulent entropy production and wall dissipation.

Focused Shear Wave Beam Propagation in Tissue-Mimicking Phantoms.

Ultrasound transient elastography (TE) technologies for liver stiffness measurement (LSM) utilize vibration of small, flat pistons, which generate shear waves that lack directivity. The most common cause for LSM failure in practice is insufficient shear wave signal at the needed depths. We propose to increase shear wave amplitude by focusing the waves into a directional beam. Here, we demonstrate the generation and propagation of focused shear wave beams (fSWBs) in gelatin. Directional fSWBs are generated by vibration at 200-400 Hz of a concave piston embedded near the surface of gelatin phantoms and measured with high-frame-rate ultrasound imaging. Five phantoms with a range of stiffnesses are employed. Shear wave speeds assessed by fSWBs are compared with those by radiation-force-based methods (2D SWE). fSWB amplitudes are compared to predictions using an analytical model. fSWB-derived shear wave speeds are in good agreement with 2D SWE. The amplitudes of fSWBs are localized to the LSM region and are significantly greater than unfocused shear waves. Overall agreement with theory is observed, with some discrepancies in the theoretical source condition. Focusing shear waves can increase the signal in the LSM region for TE. Challenges for translation include coupling piston vibration with the patient skin and increased attenuation in vivo compared to the phantoms employed here. Fibrosis is the most predictive measure of patient outcome in non-alcoholic fatty liver disease. Increased shear wave amplitude in the LSM region can reduce fibrosis assessment failure rates by TE, thus reducing the need for invasive methods like biopsy.

Relationship between water sources and diarrhea incidence in North Buton Regency

Background: The condition of water sources in the unprotected category is classified as unsafe sanitation facilities. This is very risky for endangering the people who use it as a source of clean water for their daily needs. In North Buton Regency, based on monitoring, unprotected water sources are still found, both dug wells and springs which are used by the community to meet their clean water needs. Method: quantitative analytical, with a cross sectional study design. This research was carried out using a household survey method using a questionnaire, as well as observationally using an observation sheet. The sample in this study was 3,640 households, this number was obtained from 91 villages, where each village was represented by 40 households selected using the simple random sampling method. Result: The results of this study show that there is a significant relationship between the use of dug well water sources and the incidence of diarrhea based on statistical tests using the chi square test, obtaining a p value of 0.000 < 0.05. There is a relationship between the use of spring water and the incidence of diarrhea in North Buton Regency with a p value of 0.000 < 0.05. Conclusion: There is a significant relationship between dug wells and spring water sources and the incidence of diarrhea in North Buton Regency.

Spatial assessment and chemical characterization of degraded (salt-affected) soils at post-reclamation stage of the Indo-Gangetic Plain in Haryana State.

Dynamics of soil salinity and sodicity is a common feature driven by anthropogenic causes such as soil reclamation, the effect of extreme climate events, disturbed salt, and water balance in irrigated areas that are devoid of any good quality groundwater source and adequate natural surface drainage condition in a semiarid climatic region. Periodic soil salinity assessment is therefore vital to know the current soil salinity status, plan reclamation, and/or management strategies for sustained agricultural growth and livelihood security. Temporal studies using Indian Remote Sensing (IRS) LISS III data, at pre- (1997) and post-reclamation (2017) stages have indicated spatial changes as reclaimed areas (~ 35%) and dynamics of soil salinity as increased areas (~ 61%) under irrigation across the Gangetic plain of Haryana State. The prominent areas of reclaimed sodic soil soils were located in the old alluvial plain which covered Panipat (12.32%), Karnal (6.01%), and Jind (5.9%) districts. Based on pH, ECe, and ESP values, these were classified as slight (Sso1, 8.75%), moderate (Sso2, 24.73%), and strong (Sso3, 18.20%) sodic soils, respectively. Significant salinity-inflictions (emerging areas) were identified at low-lying, poorly drained, irrigated soils in south and central Haryana that cover Jhajjar (13.99%), Sirsa (11.06%), Hisar (10.15%), Rohtak (8.73%), Bhiwani (6.43%), Palwal (4.31%), and Rewari (3.01%) districts. Slight (Ssa1, 16.82%), and moderate (Ssa2, 22.13%), categories are dominant soils, respectively. Among the landforms, significant areas (28.24%) were identified in the old alluvial plain with sand dunes (OAPSD), aeo-fluvial plain (AFP, 8.6%), and fluvio-aeolian plain (FAP, 6.0%), respectively. Dominant areas of reclaimed soils (14.4%) were identified in OAPSD. The soil analysis data indicated that these soil are moderate to strongly sodic (pH 8.7-11.0) and saline (ECe 4-26 dS m-1). The reclaimed sodic soils showed prominent improvement in soil pH and sodicity levels (pH 8.3-9.2) at 0-15cm depth and are commonly located in the Ghaggar and Yamuna river plains. Poor quality groundwater with high Residual Sodium Carbonate (RSC) was dominant at selected locations under the arid and semiarid climate. The database can also be used as a reference database for further monitoring of soil salinity status particularly in the irrigated regions. Currently, it is also used as a primary database for harmonization, monitoring, and reconciling of similar soils of the world under the Global Soil Partnership projects.

Carbon metabolism characteristics of quorum quenching bacteria Rhodococcus sp. BH4 determine the bioaugmentation efficiency under different carbon source conditions

Carbon sources are critical factors influencing bacterial bioaugmentation, however, the underlying mechanisms, particularly the metabolic characteristics of bioaugmented bacteria remain poorly understood. The bioaugmented bacterium Rhodococcus sp. BH4 secretes the quorum quenching (QQ) enzyme QsdA to disrupt the quorum sensing (QS) in the activated sludge (AS) process, reducing AS yield in-situ. This study investigated the carbon metabolic characteristics of BH4 and explored the effects on bioaugmentation with different influent carbon sources. Because of the absence of glucose-specific phosphoenol phosphotransferase system (PTS), BH4 prefers sodium acetate to glucose. However, the lactones produced during extracellular glucose metabolism enhance BH4 qsdA expression. Moreover, BH4 possess carbon catabolite repression (CCR), acetate inhibits glucose utilization. BH4 microbeads were added to reactors with different carbon sources (R1: sodium acetate; R2: glucose; R3: a mixture of sodium acetate and glucose) for in-situ AS yield reduction. During operation, AS reduction efficiency decreased in the following order: R1 > R3 > R2. R2 and R3 microbeads exhibited similar QQ activity to R1, with less BH4 biomass at 5 d. 13C labeling and Michaelis-Menten equation showed that, due to differences in the competitiveness of carbon sources, R1 BH4 obtained the most carbon, whereas R2 BH4 obtained the least carbon. Moreover, acetate inhibited glucose utilization of R3 BH4. Transcriptome analysis showed that R1 BH4 qsdA expression was the lowest, R2 BH4 was the most serious form of programmed cell death, and the R3 BH4 PTS pathway was inhibited. At 10 d, R1 BH4 biomass and microbead QQ activity were higher than that in R3, and the R2 BH4 lost viability and QQ activity. This study provides new insights into bioaugmentation from the perspectives of carbon source competitiveness, carbon metabolism pathways, and CCR.

Transfer learning neural network for reconstructing temperature field in film cooling with scarce local measurements

Film cooling is widely adopted for thermal protection of gas turbine blades. Obtaining the surface temperature field is essential for film cooling design. However, it is generally challenging because temperature measurement points are scarce in practice. Although machine learning models can be trained to reconstruct the temperature field, their accuracy is limited when the measurement points are insufficient and the explicit physical constraints are lacking. To address the problem, a transfer learning neural network (TLNN) is proposed in present study. The main idea is to learn the general characteristics of temperature field from abundant data in other working conditions as implicit constraints, and to make fine-tuning of the model for a specific working condition with scarce measurement points. Numerical simulations were conducted under various working conditions to generate dataset for model training and testing. With the blowing ratios of 1 and 0.5 used as the source and target working conditions, the mean relative L2-norm errors are 52 %, 41 %, and 32 % lower for 20, 10, and 5 measurement points, respectively, compared to the model without transfer learning. The results indicate that the proposed TLNN model can accurately reconstruct the temperature field in film cooling with scarce measurement points.