bluuebunny/crossref_metadata_2025_split huggingface dataset:
The influence of invertebrate faecal material on compositional heterogeneity, diagenesis and trace metal distribution in the Ogeechee River estuary, Georgia, USA
Authors: Swaren Logan , Hao Weiduo , von Gunten Konstantin , Wilson Sasha , Alessi Daniel S. , Planavsky Noah , Tarhan Lidya , Gingras Murray K. , Konhauser Kurt O. 
Published: October 2020

AbstractBioturbating organisms contribute significantly to elemental cycling in sediments through burrowing, grazing, organic matter and altering porewater chemical conditions. In the process, organisms are known to produce copious amounts of faecal material at high rates, sometimes in excess of 1 000 000 kg day−1 in a 1 km2 area. Material from three organisms (Arenicola marina, Callichirus major and Diopatra cuprea) was collected from two locations, Raccoon Key and Steamboat Pass, in the Ogeechee River estuary, Georgia, USA, to explore how faecal production affects organic carbon cycling and clay mineralogies. The individual organisms’ feeding strategies played a strong role in the extent to which they concentrate organic matter and lead to the formation of clay minerals. The faecal material of filter feeding Diopatra cuprea and selective deposit feeding Callichirus major contains up 45.8% and 47.3% kaolinite, respectively, while kaolinite is below detection limits in the surrounding matrix. By contrast, the non‐selective deposit‐feeder Arenicola marina does not appear to form or concentrate clay minerals. Callichirus major increases organic carbon contents at Raccoon Key by 68‐fold and Diopatra cuprea increases total organic carbon (w/w%) by 119‐fold and 32‐fold at Raccoon Key and Steamboat Pass, respectively. Arenicola marina, in contrast, does not noticeably concentrate organic matter in its faecal material, most likely as a consequence of non‐selective deposit‐feeding. Potentiometric titration data was used to explore surface reactivity and metal sorption. Diopatra cuprea and Callichirus major faecal material has strong metal binding affinities relative to the surrounding matrix, thereby increasing the potential for trace metals to be sequestered into the sedimentary record. The widespread occurrence of invertebrate faecal material enriched in clay minerals and organic matter likely has a significant influence on organic matter, grain size and trace metal distribution in estuarine sediments.
Pre‐Klondikean oxidation prepared the ground for Broken Hill‐type mineralization in South Africa
Authors: Höhn Stefan , Frimmel Hartwig E. , Debaille Vinciane , Price Westley 
Published: October 2020

AbstractNew Cu isotope data obtained on chalcopyrite from the Black Mountain and the Broken Hill deposits in the medium‐ to high‐grade metamorphic Aggeneys‐Gamsberg ore district (South Africa) require a revision of our understanding of the genesis of metamorphic Broken Hill‐type massive sulphide deposits. Chalcopyrite from both deposits revealed unusually wide ranges in δ65Cu (−2.41 to 2.84‰ NIST 976 standard) in combination with distinctly positive mean values (0.27 and 0.94‰, respectively). This is interpreted to reflect derivation from various silicate and oxide precursor minerals in which Cu occurred in higher oxidation states. Together with the observation of a typical supergene base metal distribution within the deposits and their spatial association with an unconformity only meters above the ore horizon, our new data are best explained by supergene oxidation of originally possibly SEDEX deposits prior to metamorphic sulphide formation, between the Okiepian (1,210–1,180 Ma) and Klondikean (1,040–1,020 Ma) orogenic events.
Applying ASTM Standards to Tensile Tests of Musculoskeletal Soft Tissue: Methods to Reduce Grip Failures and Promote Reproducibility
Authors: Wale Madison E. , Nesbitt Derek Q. , Henderson Bradley S. , Fitzpatrick Clare K. , Creechley Jaremy J. , Lujan Trevor J. 
Published: October 2020

Abstract
Tensile testing is an essential experiment to assess the mechanical integrity of musculoskeletal soft tissues, yet standard test methods have not been developed to ensure the quality and reproducibility of these experiments. The ASTM International standards organization has created tensile test standards for common industry materials that specify geometric dimensions of test specimens (coupons) that promote valid failures within the gage section (midsubstance), away from the grips. This study examined whether ASTM test standards for plastics, elastomers, and fiber-reinforced composites are suitable for tensile testing of bovine meniscus along the circumferential fiber direction. We found that dumbbell (DB) shaped coupons based on ASTM standards for elastomers and plastics had an 80% and 60% rate of midsubstance failures, respectively. The rate of midsubstance failures dropped to 20% when using straight (ST) coupons based on ASTM standards for fiber-reinforced composites. The mechanical properties of dumbbell shaped coupons were also significantly greater than straight coupons. Finite element models of the test coupons revealed stress distributions that supported our experimental findings. In addition, we found that a commercial deli-slicer was able to slice meniscus to uniform layer thicknesses that were within ASTM dimensional tolerances. This study provides methods, recommendations, and insights that can advance the standardization of tensile testing in meniscus and other soft fibrous tissues.
Numerical Investigation of Optimal Air Flowrate for Cooling 600 W Brushless Direct-Current Motor
Authors: Kwon Hwabhin , Park Heesung 
Published: October 2020

Abstract
Personal mobility devices have drawn growing attention to relieve the congestion of traffic and air pollution. The efficiency of electric motors is significant in terms of energy utilization, driving range, and lifetime of the devices. In this study, a brushless direct-current (BLDC) motor is numerically investigated to maximize the system efficiency. The inevitable energy losses in the motor are evaluated using heat sources generated in the motor components. The resulting copper and iron losses generate heat and decrease the motor efficiency. With these, the developed three-dimensional numerical model accurately predicts the temperature variations of the motor components in accordance with the experimental results. Numerical simulations are conducted by supplying air flow at a rate of 0 to 40 l/min. The results show that the decreased temperature at copper windings improves the efficiency of the motor as more air flowrate is supplied. Nonetheless, after the temperature at the copper windings reaches 42.5 °C at an air flow of 30 l/min, the temperature remains constant despite additional increase in the air flow. Through a comparison between the improved electrical work by cooling and the consumed energy to supply the air flowrate, the maximum efficiency of the air-cooled BLDC is found to be 86.3% with an optimal air flowrate of 30 l/min.
The Effect of Orientation on the Performance of Small Free-Convection Heat Sinks for Use With a Thermoelectric Cryotherapy Device
Authors: Baldry Mark , Timchenko Victoria , Menictas Chris 
Published: October 2020

Abstract
The rapid development of metal 3D printing techniques has enabled the exploration of complex free-convection heat sink designs. Small free-convection heat sinks with pin-fin arrays (or novel geometries) are widely employed at different orientations in a variety of electronic devices, yet there is limited understanding of how orientation impacts their heat transfer behavior. This article characterizes the orientation-dependent performance of a small, tapered pin, free-convection heat sink (named HS17) manufactured with direct metal laser sintering for use with a thermoelectric scalp cryotherapy device for the prevention of chemotherapy-induced alopecia. A validated numerical model and custom-built free-convection test rig were used to investigate the heat sink’s performance over the orientation range of 0 deg to 135 deg. HS17 maintained relatively robust performance over the 0 deg to 90 deg range; however, the thermal resistance (Rth) at 112.5 deg and 135 deg was 6% and 11% higher compared to the 90 deg case, respectively. The heat sink design was modified to include a 22.5 deg wedge base (named HS17-W) to mitigate this performance decline, which is important to ensure safe and continued operation of the cryotherapy device. Compared to the flat base heat sink, the wedge-base design successfully reduced Rth from 11.9 K/W, 12.5 K/W, and 12.8 K/W to 11.5 K/W, 11.8 K/W, and 12.3 K/W at 90 deg, 112.5 deg, and 135 deg, respectively. These results demonstrate the effectiveness of the current proposed design to improve the performance of free-convection heat sinks at downward-facing orientations.
Finite Element Evaluation of Key Approaches to Develop Insensitive Fuze
Authors: Chang Tianxiao , Wen Quan , Wang Yushi , Wang Guangyu , Jiang Chao , Yan Li 
Published: October 2020

Abstract
This paper evaluates several key approaches for their impact on the development of insensitive munition (IM) with special emphasis on the fuze. The effect of these approaches on the thermal vulnerability of a fuze is studied and evaluated by finite element analysis. These approaches include changing the proportion of the desensitizing agent, replacing the charge, changing the shell material, and adding the heat insulation coating. First, the cook-off test of a plastic-bonded explosive number-5 (PBXN-5) squib tube is simulated by abaqus and compared with the test results to validate the soundness of the proposed method. After this, comprehensive evaluations are conducted on each approach for its influence on the cook-off time. The results suggest that the weighting on the four proposed approach from high to low are insulation design, the insensitive charge, the shell material, and the proportion of the desensitizing agent, respectively.
Oxygen Crossover in Solid–Solid Heat Exchangers for Solar Water and Carbon Dioxide Splitting: A Thermodynamic Analysis
Authors: Holzemer-Zerhusen Philipp , Brendelberger Stefan , Roeb Martin , Sattler Christian 
Published: October 2020

Abstract
In solar thermochemical redox cycles for H2O/CO2-splitting, a large portion of the overall energy demand of the system is associated with heating the redox material from the oxidation temperature to the reduction temperature. Hence, an important measure to improve the efficiency is recuperation of sensible heat stored in the redox material. A solid–solid heat exchanger can be subjected to undesirable oxygen crossover, which decreases the oxygen uptake capacity of the redox material and consequently the system efficiency. We investigate the extent of this crossover in ceria-based cycles, to identify, under which conditions a heat exchanger that allows oxygen crossover can improve the system efficiency. In a thermodynamic analysis, we calculate the amount of transferred oxygen as a function of the heat exchanger efficiency and show the system efficiency of such a concept. A second law analysis is applied to the model to check the feasibility of calculated points of operation. For the investigated parameter set, the heat exchanger design improves the system efficiency by a factor of up to 2.1.
Fretting Tribocorrosion Behaviors of Marine Mooring Chain Steel 22MnCrNiMo in Artificial Seawater
Authors: Du Conghao , Bai Xiuqin , Yuan Chengqing 
Published: October 2020

Abstract
The fretting wear behaviors of mooring chain steel 22MnCrNiMo specimens were evaluated in pure water and artificial seawater using a pin-on-flat configuration with 500-μm amplitude at room temperature for 2 h. Open-circuit potential tests and potentiodynamic anodic polarization were used to measure the alloy’s corrosion behaviors. Worn specimen surfaces were observed using scanning electron microscopy and wear volume loss determined using laser-scanning confocal microscopy. Comparative analyses of friction coefficient, wear volume loss, and worn surface morphologies were conducted. The results showed that the friction coefficients of 22MnCrNiMo friction pairs were in general smaller in seawater compared with that in pure water. Comparing contact stresses, sliding velocities had greater influence on tribocorrosion behavior of friction pairs in a marine environment. Moreover, wear volume loss of this steel in seawater was lower than that in pure water, indicating that corrosion had inhibitory effects on wear. With the increase of wear degree, the corrosion degree also increased, indicating that wear occurrence promoted corrosion. This also demonstrated a transformation of positive to negative interactions between corrosion and wear in the fretting corrosion and wear processes of this steel. The wear mechanism of the mooring chain steel 22MnCrNiMo was typically abrasion wear in pure water, whereas it was corrosion fatigue in seawater.
Dynamic Simulation of Coal-Fired Power Plant Integrated With Trough Solar Collector Operating in Parallel With High Pressure Heaters
Authors: Yan Hui , Li Xin , Liu Ming , Chong Daotong , Yan Junjie 
Published: October 2020

Abstract
Solar-aided coal-fired power plant (SACFPP) is a cost-effective approach to overcome solar energy intermittency. SACFPPs frequently operate in dynamic processes due to power load and solar energy fluctuations. This study investigated the dynamic characteristics of SACFPPs; such characteristics are important for flexibility evaluation and control system design. The SACFPP used in this study was based on a 660 MW coal-fired power plant, and a trough collector system (TCS) operates in parallel with high pressure (HP) heaters. After model development and validation, the dynamic performance of the SACFPP was analyzed under four load ratios of power plant, with disturbances of two parameters: direct normal irradiance (DNI) and mass flowrate ratio to TCS. The performance was also compared with three parallel TCS connection modes. Results showed that the magnitude and response time for power variation under DNI disturbance increased with load ratio. With 500 W/m2 DNI step increments, power increased by approximately 18.4, 21.2, 24.7, and 29.8 MW in 2200, 2330, 2550 and 2620 s at 70%, 80%, 90%, and 100% load ratios, respectively, when all the HP heaters were replaced. The serial number and the number of HP heaters replaced also increased the power variation and response time. Under mass flowrate ratio to TCS increase disturbance, the power rapidly changed to its maximum and then slowly decreased, but the variation value depended on the load ratio.
Optimization of Extraction Position Under Low Loads Operation of Power Plant in Power-Water Cogeneration
Authors: Chen Weixiong , Fan Jiang , Meng Yu , Zhang Yousen , Yan Junjie 
Published: October 2020

Abstract
Power-water cogeneration is an effective mode to address fresh water shortage problem, namely low-temperature multi-effect seawater desalination (LT-MED) system coupled with thermal power plant. In the present study, the steam extraction position of thermal vapor compressor (TVC) under different loads was optimized to reduce the cost of water production. And then, the thermodynamic performance of the coupled system is obtained when the extraction position of motive steam varies from No.5 to No.7, whereas the power plant load is in the range of 30% THA – 50% THA. The results indicate that the optimal extraction position is not fixed under different low loads of the power plant, it depends on the cost calculation methods. For any method used to calculate the steam cost, the optimal steam extraction position is from No.5 extraction when the power plant load is 40%THA. The optimal steam extraction position is from No.6 extraction when the power plant load is 30%THA. And the optimal steam extraction position is from No.7 extraction when the power plant load is 30%THA.
A Novel Coal-Fired CHP System Integrated With Steam Ejectors to Realize Heat-Power Decoupling and Energy Saving
Authors: Liu Miaomiao , Liu Ming , Zhao Shuran , Song Gege , Yan Junjie 
Published: October 2020

Abstract
Traditional combined heat and power (CHP) units should run in the heat-controlled mode. The adjustable range of power load is restricted by the heat load, and the minimum power load increases with the heat load. Because of high penetration of intermittent renewable power, operational flexibility of CHP units is highly required. It is necessary to adopt some technical solutions to realize heat-power decoupling for CHP units. To find a heat-power decoupling method with low investment and high energy efficiency, the steam ejectors, simple in structure and low in cost, are applied to design a novel heat-power decoupling system in this study. Steam ejectors can recover the waste heat of exhaust steam of steam turbines. Therefore, the integration of steam ejector may realize heat-power decoupling and energy saving simultaneously. Three heat-power decoupling systems with steam ejectors are designed. The heat-power decoupling performance and energy consumption characteristics of these systems are investigated with a reference 330 MW coal-fired CHP unit. Results show that all three modified systems can realize heat-power decoupling. The heat-power decoupling performance of improved system III is the best, and improved system I has the least coal consumption rate for power generation.
Online Adaptive Control Tuning in a Gas Turbine Hybrid System
Authors: Bonilla-Alvarado Harry , Restrepo Bernardo , Pezzini Paolo , Shadle Lawrence , Tucker David , Bryden Kenneth Mark 
Published: October 2020

Abstract
Proportional integral and derivative (PID) controllers are the most popular technique used in the power plant industry for process automation. However, the performance of these controllers may be affected due to variations in the power plant operating conditions, such as between startup, shutdown, and baseload/part-load operation. To maintain the desired performance over the full range of operations, PID controllers are always retuned in most power plants. During this retuning process, the operator takes control of the manipulated variable to perform a standard procedure based on a bump test. This procedure is generally performed to characterize the relationship between the manipulated variable and the process variable at each operating condition.
After the bump test, the operator generally applies basic guidelines to assign new parameters to the PID controller. In this paper, the Model Reference Adaptive Controller (MRAC) control technique was implemented to update the PID controller parameters online without performing the bump test procedure. This approach allows updating the controller response on-the-fly while the power plant is running and without using the standard procedure based on a bump test. The MRAC was developed and demonstrated in the gas turbine hybrid cycle at the National Energy Technology Laboratory (NETL) to retune a critically damped mass flow PID controller into an over-damped response. Results showed stable performance during mass flow setpoint steps and also a stable update of the controller parameters.
Thermal Performance Evaluation of a Solar Collector Utilizing a Novel Resistance Network Model
Authors: Nokhosteen Arman , Sobhansarbandi Sarvenaz 
Published: October 2020

Abstract
Heat pipe evacuated tube solar collectors (HPETCs) are a type of solar collectors with appealing characteristics for the application in solar water heating (SWH) technologies. In order to better understand the heat transfer phenomena in HPETCs and improve their efficiency, there is a need for a fast and robust numerical tool. Due to the complexity of the heat transfer processes involved in modeling a collector’s performance, direct numerical analysis solutions (DNS) are computationally cumbersome. Recent studies have shown that resistance network (RN) models are suitable tools for studying the performance and thermal behavior of HPETCs. In this work, a novel method of resistance network based proper orthogonal decomposition (RNPOD) is presented which can not only consider the geographical and meteorological characteristics of the ambient surroundings, but also take into account the peripheral temperature distribution of a single HPETC. Once the temperatures at each instance in time have been calculated, a POD method is used to predict the thermal behavior of the collector with desired temporal accuracy. The obtained results of this study are cross-validated with the previous experimental work of the authors, illustrating that the model is able to predict the peripheral temperature distribution with a maximum error of 10%.
Chemical Kinetic Model Reduction and Analysis of Tetrahydrofuran Combustion Using Stochastic Species Elimination
Authors: Eldeeb Mazen A. , Wadugurunnehalage Malshana 
Published: October 2020

Abstract
In this work, a chemical kinetic modeling study of the high-temperature ignition and laminar flame behavior of Tetrahydrofuran (THF), a promising second-generation transportation biofuel, is presented. Stochastic Species Elimination (SSE) model reduction approach (Eldeeb and Akih-Kumgeh, Proceedings of ASME Power Conference 2018) is implemented to develop multiple skeletal versions of a detailed chemical kinetic model of THF (Fenard et al., Combustion and Flame, 2018) based on ignition delay time simulations at various pressures and temperature ranges. The detailed THF model contains 467 species and 2390 reactions. The developed skeletal versions are combined into an overall reduced model of THF, consisting of 193 species and 1151 reactions. Ignition delay time simulations are performed using detailed and reduced models, with varying levels of agreement observed at most conditions. Sensitivity analysis is then performed to identify the most important reactions responsible for the observed performance of the reduced model. Reaction rate parameter modification is performed for such reactions in order to improve the agreement of detailed and reduced model predictions with literature experimental ignition data. The work contributes toward improved understanding and modeling of the oxidation kinetics of potential transportation biofuels, especially cyclic ethers.
Study on Formation, Deposition and Fouling Prediction of Ammonium Bisulfate (ABS) at Air Preheater in Utility Boiler
Authors: Pang Liping , Liang Qiyuan , Duan Liqiang 
Published: October 2020

Abstract
The ammonium bisulfate (ABS) widely exists at air preheater. The ABS may deposit and foul at the heating elements of air preheater because of the chemical reaction between SO3 at flue gas side and ammonia slip from SCR excess injection. The heat transfer equation between flue gas side and air side is constructed and simplified using physical and mathematical models accordingly. The finite difference method is applied to solve numerically by means of iterative computation. Based on the NH3 and SO3 concentration data from the real time data in the actual operation and the discrete calculation of the temperature field, the Radian number (Ra) is used to evaluate the possibility of ABS fouling and the developing trend of heating elements at the air preheater. A 1000MW ultra supercritical boiler is selected as example. The ABS deposit area is simulated under different working conditions 100%BMCR, 75% BMCR and 50% BMCR. The possible ABS deposition and fouling is analyzed for operators to evaluate the risk of cold-end and hot-end heating elements plate at air preheater. As the working load decreases lower than 50%BMCR, the deposition and fouling position could extend to the hot-end area of heating elements at air preheater.