bluuebunny/crossref_metadata_2025 huggingface dataset:
Shadows and sparks inWuthering Heights
Authors: Panagiotopoulou Maria
Published: October 2020

The aim of this study is to present Heathcliff, the damned lover and romantic villain ofWuthering Heights, through the light of ancient tragedy. The hero that Emily Brontë created is reminiscent of the spirit, feelings, and actions of heroes of Greek mythology such as Deianeira, Oedipus, Electra, Orestes, Medea, and Hippolytus, who were perfectly presented in Sophoclean and Euripidean dramas. Condemned love, unfulfilled, repelled, and undefined passion, the repressed emotions of a child without identity, along with the social conviction and marginalization that accompany lowly and unspecified origins, become motivations for his narcissism and his desire for vengeance.Wuthering Heightsis a story about love and death, storm and night, and last but not least, about souls that cannot find peace because of their denial of each other. This is why one can either hate the repulsive personality of Heathcliff, or fall in love with his mystery and darkness, but no one can be indifferent to him. He is a tragic hero, a man that gave flesh and blood toodi et amo. While reading this article, I think that you will feel that Emily Brontë created her fictional villain–lover having captured in her mind echoes of the ancient figures mentioned above, figures who are haunted by deeply human feelings such as love, revenge, hatred, and suffering that determine their actions, identifying them with angels who eventually turn into demons.
“Sound is essentially your path in”
Authors: Deng Yingying , Qionglin Tan Joan
Published: October 2020

With the recent years’ emphasis, in literature and culture, on sound studies, Gary Snyder’s thoughts about sound and his creation of sound poetry become the critics’ new perspective on understanding his ecological consciousness. To his mind, poetry is an art of sound, and voice is “a mirror of his own deepest self.” His sound poetics is rooted in his evolutionary cognitive understanding of voice and sound, and aesthetically manifests itself in three characteristics: the emphasis on “suchness” and origination when sound is treated as an object of poetry; the presentation of immediacy and musicality when properties of sound are adapted as a component of poetic rhythm; the expression of nonduality when sound shows itself as a deconstruction of dualism. This article argues that Snyder conceptualizes his sound ethics—what may be understood as his “Way of Sound”—by affirming the sound of the wilderness in the subjectivity of natural speech and cultivating an ethical attitude of “no‐self” and “inhumanism” in listening to inner whispers of the universe heard in religious meditation.
Healthcare utilization in Danish children with atopic dermatitis and parental topical corticosteroid phobia
Authors: Gerner Trine , Haugaard Jeanette Halskou , Vestergaard Christian , Deleuran Mette , Jemec Gregor Borut , Mortz Charlotte Gotthard , Agner Tove , Egeberg Alexander , Skov Lone , Thyssen Jacob P.
Published: October 2020

Background

Atopic dermatitis (AD) is a prevalent relapsing inflammatory skin disease. There is currently little knowledge about healthcare utilization and medication use along with parental corticosteroid phobia in relation to severity of pediatric AD.

Objectives

To study the association between parental‐reported healthcare utilization, medication use, and topical corticosteroid phobia and pediatric AD severity.

Methods

The study population included all children in Denmark with a diagnostic code of AD (ICD‐10 code, group L20) given at a hospital department of dermatology between 2014 and 2018. A questionnaire containing 158 response items was sent to the legal parents. We surveyed disease severity, AD treatment, corticosteroid phobia, and healthcare use along with other variables. Disease severity was assessed using the Patient‐Oriented Eczema Measure tool, and corticosteroid phobia was assessed using the Topical Corticosteroid Phobia (TOPICOP) score.

Results

In total, 1343 (39%) parents completed the questionnaire and 95.3% were completed by the biological mother. Children's mean age was 8.9 ± 4.5 years, and 52.8% were boys. Severe AD was associated with a higher number of healthcare visits to GPs, private dermatologists, and hospital departments. Mean global TOPICOP score was 38.27 ± 19.9%. There was a significant inverse linear trend between global TOPICOP score and parental educational level (Ptrend < .0005).

Conclusions

The significant association between high global TOPICOP score and low parental educational level, resulting in delayed treatment of AD flares, indicates that improved family education ultimately may reduce healthcare expenses and burden of disease.
Light signalling shapes plant–plant interactions in dense canopies
Authors: Huber Martina , Nieuwendijk Nicole M. , Pantazopoulou Chrysoula K. , Pierik Ronald
Published: October 2020

Plants growing at high densities interact via a multitude of pathways. Here, we provide an overview of mechanisms and functional consequences of plant architectural responses initiated by light cues that occur in dense vegetation. We will review the current state of knowledge about shade avoidance, as well as its possible applications. On an individual level, plants perceive neighbour‐associated changes in light quality and quantity mainly with phytochromes for red and far‐red light and cryptochromes and phototropins for blue light. Downstream of these photoreceptors, elaborate signalling and integration takes place with the PHYTOCHROME INTERACTING FACTORS, several hormones and other regulators. This signalling leads to the shade avoidance responses, consisting of hyponasty, stem and petiole elongation, apical dominance and life cycle adjustments. Architectural changes of the individual plant have consequences for the plant community, affecting canopy structure, species composition and population fitness. In this context, we highlight the ecological, evolutionary and agricultural importance of shade avoidance.
A study on stress response and fertility parameters in phenotypically thermotolerant and thermosensitive dairy cows during summer heat stress
Authors: Nanas Ioannis , Chouzouris Thomas‐Markos , Dadouli Katerina , Dovolou Eleni , Stamperna Konstantina , Barbagianni Mariana , Valasi Irini , Tsiaras Anastasios , Amiridis Georgios S.
Published: October 2020

It is well documented that heat stress (HS) causes subfertility in dairy cows. However, during the last ten years we have been observing that, under high temperature–humidity index (THI ≥ 75), despite the overall reduced fertility, some cows conceive at the first artificial insemination (AI). Here, we examined distinctive features of cows with conserved fertility under severe HS. From the databases of three herds, 167 lactating Holstein cows were selected; group TT cows (n = 57) conceived in the previous summer (THI ≥ 75) at the 1st AI, and group TS (n = 110) failed to conceive at the same period after at least 2 consecutive AIs. The animals calved in spring, and in August, blood samples were collected during a hot day (THI ≥ 81) for the determination of cortisol and HSP70 concentrations. In one farm, the validity of fertility data of the previous year was re‐examined. In 28 cows from group TT and in 39 cows from group TS, the conception rate was examined during July and August. In 6 cows from each group (TT and TS) the oestrous cycles were synchronized, ovulation was induced with GnRH (THI = 80), and the concentration of the pre‐ovulatory LH surge was determined in 9 blood samples. The progesterone concentration in the ensuing cycle was determined in blood samples collected every other day. Overall, cortisol and HSP70 were significantly lower in TT group compared to TS. More (p < .05) animals from group TT conceived at the first AI compared with those from group TS. The induced pre‐ovulatory LH surge peaked at higher level (p < .002) in group TT than in group TS, while no difference was recorded among groups either in mean progesterone concentrations or in the duration of the ensuing oestrous cycle. These results are highly suggestive that thermotolerance in some dairy cows is an inherent characteristic, warranting further genetic investigation.
Endometrial expression of key genes related to fertility in repeat breeder and non‐repeat breeder cows
Authors: Jaureguiberry María , Madoz Laura Vanina , Quintana Silvina , Marín Maia , Burucúa Mercedes , Tizzano Marco , Rabaglino Belén , Rearte Ramiro , Pecoraro Marcelo Ítalo , de la Sota Rodolfo Luzbel
Published: October 2020

The aim of the present study was to compare the endometrial gene expression of epidermal growth factor receptor (EGFR), nodal growth differentiation factor (NODAL), prostaglandin‐endoperoxide synthase 2 (PTGS2), oestrogen receptor 1 (ESR1) and progesterone receptor (PGR) in repeat breeder cows (RBC) and non‐RBC during diestrus. Endometrial samples were collected by cytobrush technique and stored in RNA stabilizing solution at −20°C until RT‐qPCR analysis. Differences in endometrial mRNA expression of selected genes were assessed by ANOVA and simple (r) and the partial correlations (rp) among selected genes were performed. Results demonstrated that mRNA expression of EGFR and NODAL were higher in RBC than in non‐RBC (3 and 25‐fold change, p < .01 and p < .01, respectively), while the mRNA expression of PTGS2 was lower (1.56‐fold change, p < .01). Although there were no differences detected in the mRNA expression of ESR1 and PGR, there was a positive correlation between the expression of ESR1 and EGFR (0.84, p < .05) and a negative correlation between PGR and PTGS2 (−0.49, p < .05). In conclusion, the difference on the endometrial mRNA expression of the genes included in the study between RBC and non‐RBC indicates a deregulation of important mechanisms that are vital to establish a successful pregnancy. Thus, the present study provides useful insight as a base for future studies to elucidate the causes of RBC.
Modeling the Dose Response Relationship of Waterborne Acanthamoeba
Authors: Dean Kara , Tamrakar Sushil , Huang Yin , Rose Joan B. , Mitchell Jade
Published: October 2020

This study developed dose response models for determining the probability of eye or central nervous system infections from previously conducted studies using different strains of Acanthamoeba spp. The data were a result of animal experiments using mice and rats exposed corneally and intranasally to the pathogens. The corneal inoculations of Acanthamoeba isolate Ac 118 included varied amounts of Corynebacterium xerosis and were best fit by the exponential model. Virulence increased with higher levels of C. xerosis. The Acanthamoeba culbertsoni intranasal study with death as an endpoint of response was best fit by the beta‐Poisson model. The HN‐3 strain of A. castellanii was studied with an intranasal exposure and three different endpoints of response. For all three studies, the exponential model was the best fit. A model based on pooling data sets of the intranasal exposure and death endpoint resulted in an LD50 of 19,357 amebae. The dose response models developed in this study are an important step towards characterizing the risk associated with free‐living amoeba like Acanthamoeba in drinking water distribution systems. Understanding the human health risk posed by free‐living amoeba will allow for quantitative microbial risk assessments that support building design decisions to minimize opportunities for pathogen growth and survival.
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

Bioturbating 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

New 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.
Reuse of Treated Municipal Wastewater from Constructed Wetlands for Cut Flowers Irrigation in Aeroponic Cultivation
Authors: Vera-Puerto Ismael Leonardo , Olave-Vera Jorge Leonardo , Tapia Sussy , Chávez Wladimir Antonio , Arias Carlos
Published: October 2020

The aim of this work is to evaluate the reuse of municipal wastewaters treated through subsurface constructed wetlands (SS-CWs) as irrigation water in cut flower aeroponic cultivation under arid conditions. For this purpose, two experimental aeroponic cultivation systems were installed with the cut flower Lilium ‘Tresor’ planted and irrigated with SS-CWs treated water. The results showed that the quality of the SS-CWs wastewater has to be improved to be used in irrigation. Despite that, Lilium ‘Tresor’ grew under arid conditions with normal stem diameters and number of flowers but with heights under 0.65 m, which would restrict their commercialization to local markets. Water electrical conductivity (> 2300 µs/cm) and luminosity (> 120 klux) were factors that affected plant height. When compared to other cultivation systems, the aeroponic cultivation system used between 10 % and 20 % of the amount of water needed to produce Lilium ‘Tresor.’ Thus, this work showed the feasibility to produce cut flowers using an aeroponic cultivation system under arid conditions and irrigated with SS-CWs effluents. Likewise, it was detected that improvements to water quality and luminosity must be made for industrial scaling.
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

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

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

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

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

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

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

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

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

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

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

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

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

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.
Low-Grade Heat Utilization Through Ultrasound-Enhanced Desorption of Activated Alumina/Water for Thermal Energy Storage
Authors: Daghooghi Mobarakeh Hooman , Bandara Keshawa , Wang Liping , Wang Robert , Phelan Patrick E. , Miner Mark
Published: October 2020

Sorption thermal energy storage (TES) seems to be an auspicious solution to overcome the issues of intermittent energy sources and utilization of low-grade heat. Ultrasound-assisted adsorption/desorption of water vapor on activated alumina is proposed as a means of low-grade heat utilization through TES. The effects of ultrasonic power on the storing stage (desorption of water vapor) were analyzed to optimize the desorption and overall efficiencies. To determine and justify the effectiveness of incorporating ultrasound from an energy-savings point of view, an approach of constant total (heat plus ultrasound) input power of 25 W was adopted. To measure the extent of the effectiveness of using ultrasound, ultrasonic-power-to-total power ratios of 0.2 and 0.4 were investigated and the results compared with those of no-ultrasound (heat only) at the same total power. The regeneration temperature and desorption rate were measured simultaneously to investigate the effects of ultrasonication on regeneration temperature and utilization of low-grade heat. The experimental results showed that using ultrasound facilitates the regeneration of activated alumina at both power ratios without increasing the total input power. With regard to regeneration temperature, incorporating ultrasound decreases the regeneration temperature hence justifying the utilization of low-grade heat for thermal energy purposes. In terms of overall energy recovery of the adsorption thermal storage process, a new metric is proposed to justify incorporating ultrasound and any other auxiliary energy along with low-grade heat.
Performance Analysis and Optimization of Flue Gas Waste Heat Recovery System of a 600MW Coal-Fired Power Plant
Authors: Chen Xun , Xu Shu , Yang Yi , Wang Li-min , Wang Dun-dun
Published: October 2020

Recovering the waste heat of the flue gas from the boilers of coal-fired units, so that part of the boiler’s flue gas waste heat can be utilized in the turbine regenerative heating system is an important way to increase efficiency and reduce emissions of coal-fired units. In this paper, a 600MW supercritical coal-fired unit is taken as an example, and the conceptual design of a flue gas waste heat cascade utilization system is carried out. Based on the first and second laws of thermodynamics, the thermodynamic perfection of the heat transfer process of the rotary regenerative air preheater, the exergy efficiency of the heat displacement process of the flue gas waste heat cascade utilization system, and the overall performance parameters of the coal-fired unit are calculated and analyzed under different parameters such as the bypass flue ratio and the inlet air temperature of the regenerative air preheater. The energy-saving effect of flue gas waste heat cascade utilization system is restricted by factors such as acid dew point temperature, ammonium bisulfate (ABS) deposition inside the air preheater, etc. Based on the performance analysis of regenerative air preheater and ABS deposition law, considering the structural characteristics and operating parameters of air preheater, this paper gives a criterion number (R-number) of ABS deposition tendency, and analyzes the actual operation performance of flue gas waste heat cascade utilization system considering the restrictions.
Data Analytics Applied to Coal Fired Boilers for Detecting Leaks
Authors: Indrawan Natarianto , Panday Rupendranath , Shadle Lawrence J. , Chitnis Umesh K.
Published: October 2020

Data analytics were used to detect boiler leaks from five different coal-fired boilers including both subcritical and supercritical systems. Discriminant functions were developed that detected leaks up to two weeks prior to forced plant shutdowns for repairs. The leaks were identified to occur at different sections of the boiler for each plant, including waterwalls, economizer and superheater using conventional process measurement data. Leaking conditions were detected with a high degree of confidence (≪ 1% misclassified observations) and were able to distinguish normal operations from those time periods with steam leaks even while operating the power plants in power cycling mode.

Multivariable statistical analyses, including Principal Component (PCA), cluster, and Fischer Discriminant Analysis (FDA) were used to characterize the leak occurrence. Normal and operational states with steam leaks were provided in the original process datasets. These datasets were split into two different groups for training and validation purposes. The data were sorted chronologically, and every third observation was assigned to training the Discriminant Function Model (DFM) while the rest were reserved for validation. PCA was used to reduce dimensionality of the original datasets. Canonical and FDA analyses were used to investigate the relationship between process variables. The outcome of the analyses revealed that nearly 35,000 observations were classified correctly; less than 0.05% of total observations were misclassified to be leaking, i.e. both false positives and false negatives.
Extending Life Expectancy of La Esmeralda Reservoir: A Bet to Support Colombia’s Future Energy Demand
Authors: del Río David A. , Moffett Hugo , Nieto-Londoño César , Vásquez Rafael E. , Escudero-Atehortúa Ana
Published: October 2020

This work addresses the strategy of AES Corporation (AES Chivor) in order to extend the life of La Esmeralda reservoir to support Colombia’s future energy demand. Chivor Hydropower Plant entered into service in 1978 and has a capacity of 1000 MW, 8 % of Colombia’s demand. It is first described how the Colombian electricity energy mix is composed. Then, La Esmeralda reservoir, which is used by Chivor for power generation, is described; sediment management plans and maintenance costs for equipment and infrastructure are addressed. Then, sediment dynamics studies that have been done in order to determine life expectancy of La Esmeralda reservoir are listed. Such studies have been used to execute the Chivor’s Life Extension Project, which considers the modification of intakes as the best option to extend the life of the reservoir for at least 50 years, among several alternatives that were evaluated by a panel of international experts. This represents a challenge from the engineering point of view, and the project will be shown as a successful example for a country with such dependence on hydropower generation. Modernizing existing infrastructure without affecting the operation, as in this case, is crucial to show how a sustainable sediment management plan and technological development are necessary to extend life of hydropower generation projects, and to help meeting energy demand in a sustainable way for countries such as Colombia with a growing economy.
A Take on Wake Modeling of Turbines Based on Deep Learning
Authors: Ziaei Dorsa , Goudarzi Navid
Published: October 2020

Analyzing real-world engineering problems such as wake modeling of wind/ocean current turbines are known to be complex and challenging. The multivariable nature of these problems requires either the implementation of computational analyses under certain simplifying assumptions or conducting experiments for a limited number of scenarios. Hence, there is always several fundamental features missed in understanding the key players in determining the complex turbulent velocity fields within the wake of turbines. It becomes more critical when studying the optimization of wind/ocean renewable farms with more than one turbine to determine the true power density or cost of energy.

Machine learning (ML) algorithms suggest promising complementary solutions to the existing physics-based (e.g. wind farm wake modeling) techniques. Implementation of conventional ML algorithms that require long-term historical data is either not feasible in many real-case applications or very expensive and time-consuming. Moreover, there are often infinite features in dataset with complex relation between them. It makes the tasks of feature selection and model tuning more challenging. In this work, a cross-domain study of physics and ML models is performed to show the need of integration of these domains. The key achievement of this work is two-fold: first, suggesting a group of emerging generative models (e.g. Generative Adversarial Networks) in the wake modeling domain; second, reducing the computational cost by demanding either smaller or no simulation dataset.
Analysis of Current Hybrid-Electric Automobile Drivetrains and Proposal of an Alternative Powertrain
Authors: Ahn Andrew , Welles Thomas S. , Akih-Kumgeh Benjamin
Published: October 2020

Byproducts of fossil fuel combustion contribute to negative changes in the global climate. Specifically, emissions from automobiles are a major source of greenhouse gas pollution. Efforts to minimize these harmful emissions have led to the development and sustained improvement of hybrid drivetrains in automobiles. Despite many advancements, however, hybrid systems still face substantial challenges which bear on their practicality, performance, and competitive disadvantage in view of the low cost of today’s traditional internal combustion engines. These imperfections notwithstanding, hybrid electric vehicles have the potential to play significant roles in the future as cleaner transportation solutions. Actualization of this potential will depend on the ability of hybrid-electric vehicles to minimize their disadvantages while increasing their positive features relative to traditional combustion engines. This research investigates current hybrid electric architectures in automobiles with the aim of suggesting an alternative, more efficient hybrid configuration that utilizes current technology. This is completed by utilizing an iterative design process to compare how various components of existing hybrids can be combined and/or improved to develop a single, efficient and cohesive system that performs comparably to or surpasses existing ones in fuel efficiency and low emissions in all driving conditions. A critical and comparative analysis is provided based on current hybrid-electric vehicle architectures as well as a plausible alternative.
Treatment Outcomes and Adverse Drug Effects of Ethambutol, Cycloserine, and Terizidone for the Treatment of Multidrug-Resistant Tuberculosis in South Africa
Authors: van der Walt Martha L. , Shean Karen , Becker Piet , Keddy Karen H. , Lancaster Joey
Published: October 2020

Treatment outcomes among multidrug-resistant tuberculosis (MDR-TB) patients receiving ethambutol, cycloserine, or terizidone as part of a standardized regimen were compared, determining occurrence of serious adverse drug events (SADEs). Newly diagnosed adult MDR-TB patients were enrolled between 2000 and 2004, receiving a standardized multidrug regimen for 18 to 24 months, including ethambutol, cycloserine, or terizidone. Cycloserine and terizidone were recorded individually. SADEs and factors associated with culture conversion and unfavorable treatment outcomes (default, death, treatment failure) were determined.