bluuebunny/crossref_metadata_2025 huggingface dataset:
ESTIMATING TEMPTATION AND COMMITMENT OVER THE LIFE CYCLE
Authors: Kovacs Agnes , Low Hamish , Moran Patrick
Published: October 2020

This article estimates the importance of temptation for consumption smoothing and asset accumulation in a life‐cycle model. We use two complementary estimation strategies: first, we estimate the model‐implied Euler equation; second, we match liquid and illiquid wealth accumulation using the method of simulated moments. In both cases, we find that the utility cost of temptation is one‐quarter of the utility benefit of consumption. Further, temptation is crucial for correctly estimating the elasticity of intertemporal substitution (EIS): EIS estimates are biased downward when ignoring temptation. Finally, the model only matches the share of illiquid wealth if temptation is in the preference specification.
Asexuality
Authors: Brunning Luke , McKeever Natasha
Published: October 2020

Asexuality is overlooked in the philosophical literature and in wider society. Such neglect produces incomplete or inaccurate accounts of romantic life and harms asexual people. We develop an account of asexuality to redress this neglect and enrich discussion of romantic life. Asexual experiences are diverse. Some asexual people have sex; some have romantic relationships in the absence of sex. We accept the common definition of asexuality as the absence of sexual attraction and explain how sexual attraction and sexual desire differ by giving an affordance‐like account of sexual attraction. Armed with that distinction, we show that asexuality is clearly different from celibacy or disorders of desire and that some existing philosophical theories of sexual desire struggle to accommodate asexual sexuality. We then build on asexual testimony about the diversity of non‐sexual attractions to answer two common objections levelled at asexual romance: that romantic relationships require sexual attraction or that sex in the absence of sexual attraction is insufficiently focused on someone as an individual. Finally, we describe some of the ways asexuality has been erased or denigrated in society, and the specific injustices and harms that result.
Vibration attraction response is a plastic trait in blind Mexican tetra (Astyanax mexicanus), variable within subpopulations inhabiting the same cave
Authors: Espinasa Luis , Heintz Carly , Rétaux Sylvie , Yoshisawa Masato , Agnès François , Ornelas‐Garcia Patricia , Balogh‐Robinson Robert
Published: October 2020

Animals evolve their sensory systems and foraging behaviours to adapt and colonize new and challenging habitats such as the dark cave environment. Vibration attraction behaviour (VAB) gives fish the ability to locate the source of a water disturbance in the darkness. VAB evolved in the blind Mexican cave tetra, Astyanax mexicanus. VAB is triggered in cavefish by vibration stimuli peaking at 35 Hz, which is within the main spectrum of water fluctuations produced by many prey crustaceans and insects. VAB has a genetic component and is correlated to an increased number of head mechanosensory neuromasts in the eye orbital region when compared to surface fish. Previous competitive prey capture assays have supported the advantage of VAB for foraging in the dark. Despite its putative adaptive function, VAB has been described as absent in some Astyanax cave populations (Tinaja and Molino) but present in others (Pachón, Piedras, Toro and Sabinos). Here we have tested the occurrence of VAB in the field and in multiple cave populations using a vibrating device in natural pools. Our results confirmed the presence of VAB in caves such as Pachón, Toro and Sabinos but showed that VAB is also present in the Tinaja and Molino cave populations, previously reported as VAB‐negative in laboratory experiments. Thus, VAB is available throughout the range of hypogean A. mexicanus. However, and most notably, within a given cave the levels of VAB were highly variable among different pools. Fish at one pool may express no VAB, while fish at another nearby pool of the same cave may actively show VAB. While a variety of environmental conditions may foster this diversity, we found that individuals inhabiting pools with a high abundance of organic matter have reduced expression of VAB. In contrast, in pools with little organic debris where fish probably depend more on hunting than on scavenging, VAB is enhanced. Our results suggest that expression of VAB is a plastic trait whose variability can depend on local conditions. Such plasticity may be required within and among caves where high environmental variability between pools results in a diverse availability of food.
Diagnostic accuracy of serum proteinase 3 antineutrophil cytoplasmic antibodies in children with ulcerative colitis
Authors: Mizuochi Tatsuki , Arai Katsuhiro , Kudo Takahiro , Nambu Ryusuke , Tajiri Hitoshi , Aomatsu Tomoki , Abe Naoki , Kakiuchi Toshihiko , Hashimoto Kunio , Sogo Tsuyoshi , Takahashi Michiko , Etani Yuri , Takaki Yugo , Konishi Ken‐ichiro , Ishihara Jun , Obara Hitoshi , Kakuma Tatsuyuki , Kurei Shunsuke , Yamashita Yushiro , Mitsuyama Keiichi
Published: October 2020

Background and Aim

Serologic markers such as myeloperoxidase (MPO) antineutrophil cytoplasmic antibodies (ANCA) (MPO‐ANCA) have been used to screen patients for ulcerative colitis (UC). However, MPO‐ANCA shows limited accuracy in Asians. Proteinase 3 ANCA (PR3‐ANCA) has performed better at UC diagnosis in Japanese adults than MPO‐ANCA. The present study aimed to evaluate usefulness of PR3‐ANCA for diagnosis of UC in Japanese pediatric practice.

Methods

Patients under 17 years old undergoing assessment at 12 Japanese pediatric centers between November 2016 and February 2018 were prospectively enrolled and divided into groups with UC, Crohn's disease (CD), intestinal disease control (IC), and healthy control (HC). Serum PR3‐ANCA and MPO‐ANCA were analyzed using chemiluminescence enzyme immunoassay kits.

Results

Sera from 367 patients (148 with UC at a median age of 12 years; 120 with CD, 13 years; 56 with IC, 10.5 years; and 43 with HC, 10 years) were examined. Median PR3‐ANCA values in UC (1.6 U/mL) were greater than in CD (0.2; P < 0.001), IC (0.15; P < 0.001), and HC (0.1; P < 0.001). In receiver operating characteristic curve analyses, the area under the curve for PR3‐ANCA was 0.79, significantly greater than for MPO‐ANCA (0.58; P < 0.001). Using a cut‐off value of 0.8 U/mL determined from the receiver operating characteristic analyses, PR3‐ANCA showed significantly greater sensitivity (64.9%) than MPO‐ANCA (cut‐off, 0.2 U/mL; sensitivity, 19.6%; P < 0.001) and good specificity (83.6%).

Conclusions

In Japanese children and adolescents, PR3‐ANCA performed better as a serologic marker for diagnosis of UC than MPO‐ANCA. To our knowledge, this is the first report of such a comparison.
“WAY”: A practical means to identify and treat the aging process
Authors: Farollch Prats Lisandro , Mirada Donisa Eduard , Villanueva Cristina
Published: October 2020

Background

Many patients consult a specialist in esthetics to improve certain aspects of their face that are altered by aging. To ensure optimal results and to define the best approach for such interventions, it is important that specialists have a comprehensive understanding of facial anatomy and of the aging process in the regions of interest.

Aims

The main purpose of this article was to provide a practical approach for managing aging process in the mid‐ and lower face. Additionally, this paper also aimed to describe the processes associated with aging that may affect the morphology and the appearance of jaw contour (“W”); prejowl (“A”); tear trough, palpebromalar area, and nasojugal groove (“Y”) (“WAY”) signs.

Methods

The Current paper combined the authors experience with the currently available scientific evidence.

Results

In this study, the anatomy and the changes associated with aging of the mandibular line and that of the tear trough, palpebromalar area, and nasojugal groove was described. The important anatomical changes in these facial regions can be considered through the “WAY” paradigm, signs of aging that can be treated through a variety of surgical and nonsurgical approaches. Although surgical procedures may obtain good results, patients generally prefer less invasive treatments, which have a good efficacy profile, but are safer and have a shorter recovery time.

Conclusions

The “WAY” signs identify anatomical changes in the mandibular line and tear trough, palpebromalar area, and nasojugal groove associated with aging that can be corrected by different procedures, preferably minimally invasive ones.
Reactive oxygen species, glutathione, and vitamin E concentrations in dogs with hemolytic or nonhemolytic anemia
Authors: Woolcock Andrew D. , Serpa Priscila B. S. , Santos Andrea P. , Christian John A. , Moore George E.
Published: October 2020

Background

Red blood cells (RBC) are uniquely susceptible to oxidative injury. Oxidative stress is both a cause for, and effect, of anemia in people but this has been minimally documented in dogs.

Objective

To describe direct and indirect markers of oxidative stress in anemic dogs.

Hypothesis

Anemic dogs will have oxidative stress when compared to healthy dogs.

Animals

Forty‐seven dogs with anemia (10 with hemolytic anemia) and 70 healthy control dogs.

Methods

Prospective, cross‐sectional study. Anemic dogs were identified from the patient population, and medical records were reviewed to classify the anemia as hemolytic or nonhemolytic. Flow cytometry was used to detect reactive oxygen species (ROS) in erythrocyte isolates. Reduced glutathione (GSH) concentrations were measured in both plasma and hemolysate samples, and vitamin E was measured in serum.

Results

Anemic dogs (both hemolytic and nonhemolytic) had significantly lower median RBC hemolysate GSH concentrations (3.1 μM [0.4‐30.8]) when compared to healthy dogs (7.0 μM [0.5‐29.7]; P = .03). Dogs with hemolytic anemia had significantly higher median plasma GSH (7.6 μM [0.4‐17.8]) when compared to dogs with nonhemolytic anemia (1.6 μM [0.01‐7.1]; P = .04) and healthy dogs (2.8 μM [0.1‐29.9]; P < .0001). Reactive oxygen species were detectable in all samples, but there was no difference in ROS or vitamin E between groups.

Conclusions and Clinical Importance

Oxidative stress is present in anemic dogs. Derangements in biomarkers of oxidative stress are different in dogs with hemolytic anemia and nonhemolytic anemia.
Teacher and Students' Mathematics Anxiety and Achievement in a Low‐Income National Context
Authors: Richland Lindsey Engle , Naslund‐Hadley Emma , Alonzo Haydee , Lyons Emily , Vollman Elayne
Published: October 2020

Negative relationships between mathematics anxiety and achievement appear in many countries globally (Lee, 2009; OECD, 2013), suggesting that mathematics anxiety could be an underconsidered factor in regions with persistently low mathematics achievement. We draw on a national sample of students and their teachers in Belize to examine relations between mathematics anxiety and achievement. The data replicated the negative relationships between students' math anxiety and achievement observed in many higher achieving, higher resourced regions, and importantly also revealed that teachers' mathematics anxiety predicted their students' mathematics attitudes and sometimes achievement. The effects were small overall so the robustness of this relationship is not clear, but they provide novel data toward building a comprehensive theory of mathematics anxiety's relationship to achievement across cultural, gender and age contexts, and offer insight into how addressing mathematics anxiety might improve mathematics teaching and achievement in low resourced countries.
The impact of foreign capital flows on long‐term interest rates in emerging and advanced economies
Authors: Inoguchi Masahiro
Published: October 2020

This paper explores how foreign capital flows affect domestic long‐term interest rates. This is especially important in emerging economies when compared with advanced economies. We employ panel data to infer the yields of 10‐year government bonds along with the government bond inflows associated with foreign investors. We then use a regression approach to examine the differences in the interest rate effects between emerging and advanced economies before and after the global financial crisis (GFC). The results suggest that while government bond inflows influenced the government bond yields of emerging economies after the GFC, this was not the case for them before the GFC nor in small advanced economies before or after the GFC. Further, we find the purchase (sale) of government bonds by foreign investors corresponded to large decreases (increases) in emerging economy bond yields. Overall, the findings suggest that the massive government bond inflows associated with foreign investors after the GFC exerted a significant impact on long‐term interest rates in emerging economies.
Intestinal SALSA/dmbt1 levels are decreased in prematurely born infants
Authors: Reichhardt Martin Parnov , Messing Marcel , Andersson Sture , Kolho Kaija‐Leena , Meri Seppo
Published: October 2020

The first months of life represent a crucial time period for an infant. Alongside establishing the early microbiome, the mucosal immunological homeostasis is being developed. Both processes may be perturbed in prematurely born infants. The glycoprotein SALSA plays a role in mucosal inflammation and microbial clearance. It is one of the most abundant molecules on the intestinal mucosal surfaces in early life. SALSA binds to many types of microbes and host defence molecules like IgA, C1q and collectin molecules. We here describe the development in faecal SALSA levels during the first three months of life. During these 90 days, the median SALSA level in full‐term babies decreased from 1100 μg/mL (range 49‐17 000 μg/mL) to 450 μg/mL (range 33‐1000 μg/mL). Lower levels of SALSA were observed in prematurely born infants in the same time period. Our novel observation thus indicates an impact of prematurity on an important component of the infant intestinal immune system. Changes in SALSA in early life may have an effect on the early establishment of the human microbiome.
Functional recovery in human partial thickness skin wounds after application of multicomponent hydrolipidic film (MAS063DP): A prospective, open‐label, comparative clinical trial
Authors: Lin Erh‐Ti , Lin Bor‐Shyh , Tsai Li‐Cheng , Chen Wei‐Kung , Wang Yen‐Jen , Chiang Hsiu‐Mei , Chang Chang‐Cheng
Published: October 2020

Acute and minor skin wounds are common in daily life. However, in clinical practice, after initial management in the acute phase, the wounds are managed mainly through observation, and the patients are usually lost to follow‐up. Considering a multicomponent hydrolipidic dressing (MAS063DP) long‐known for its safe application in eczema and recently in laser‐induced wounds, we aimed to evaluate its ability in functional recovery of impaired skin integrity during wound healing. Sixteen patients (N = 16) were enrolled and completed (n = 8 vs n = 8) this prospective, open‐label, vehicle‐controlled clinical trial with 12‐week follow‐up. Transepidermal water, skin viscoelasticity and bioimpedance analysis were measured initially, at the 1st, 4th, 8th, and 12th weeks. Improvements in these parameters were greater in the MAS063DP group (from 31.4 ± 9.0 to 16.4 ± 4.3 g/m2 h, P < .001; from 77 ± 16% to 88 ± 9%, P < .05; from 4182 ± 3823 to 2644 ± 1772 Ω) than in the white petrolatum group. No significant adverse events occurred, and all participants were more satisfied with the intervention. In this study, MAS063DP can restore skin integrity and reinstitute physiologic function as a feasible and safe intervention more markedly than management through observation during the healing process by providing protective hydrolipidic layer on the skin with simultaneous anti‐inflammatory and antioxidant activities from its key ingredients such as glycyrrhetinic acid, Vitis vinifera, telmesteine, and vitamins C and E.
Thermal Characteristics of a Three-Dimensional Coil Type Pulsating Heat Pipe at Different Heating Modes
Authors: Abraham Satyanand , Takawale Anand , Stephan Peter , Pattamatta Arvind
Published: October 2020

The heat transfer performance of a pulsating heat pipe (PHP) configured as a three-dimensional (3D) structure is reported in the present study. The PHP structure resembles an elongated coil and termed “coil type PHP.” Five different heating modes were created by positioning the evaporator at different locations and placing the PHP device in vertical and horizontal orientations. Studies were conducted primarily with de-ionized water as the working fluid. Limited number of experiments were also performed using binary fluids. The filling ratio was varied from 40% to 80%, while the heat input was varied from 20 W to 240 W. The vertical and horizontal orientations show almost 30 and 10 times reduction in the thermal resistance, respectively, compared with bare PHP tubes without the working fluid. This results in an effective thermal conductivity of more than 3000 W/(m K) and 12,000 W/(m K) for horizontal and vertical orientations, respectively. The use of the binary fluid (10 wt% and 20 wt% of ethanol aqueous solution) results in an increase in the maximum heat input at different heating modes. The temperature of the coolant supplied to the condenser section of the PHP was also varied, and the thermal resistance of the system was observed to reduce with an increase in the coolant temperature.
Yield and Empirical Relationship for a Stirling Cryocooler Liquid Air Energy Storage System
Authors: Girouard Christopher M. , Pollman Anthony G. , Hernandez Alejandro
Published: October 2020

Energy storage is a necessary design consideration to address intermittent generation on islanded, renewable microgrids. Using renewable energy in excess of immediate demand, Liquid Air Energy Storage (LAES) can produce and cryogenically store liquefied air for recovery and power generation later. While LAES has been demonstrated for large-scale energy storage, current designs use heat exchangers, expansion turbines, and co-located industrial processes. This study explores the use of simpler, low-pressure equipment, which may be suitable for smaller-scale applications. A prototype using a Stirling cryocooler for liquefaction, a vacuum dewar for storage, and a Stirling engine for energy recovery was built, tested, and analyzed. This paper focuses on quantifying the liquid air production for the prototype. A series of experiments was ran to gather data on liquid yield as a function of time for different power settings, dewar sizes and dewar shapes. An empirical relationship, useful for modeling, simulation, and design, was developed. Future work will include design, simulation, and construction of a new prototype for a specific capability. This work is part of a larger effort to determine the feasibility of different energy storage methods for small, mobile applications as well as fixed infrastructure energy storage systems.
Addressing the Energy Trilemma With LPG-Fuelled, Water-Free Combined Cycle Power Plants
Authors: Welch Michael
Published: October 2020

Many parts of the world are facing the triple challenge of providing secure energy to fuel economic growth at an affordable cost while minimizing the impact of energy production on the environment. Island nations especially struggle to address this trilemma, as renewable resources are usually limited and fossil fuels imported.

Traditionally such distributed power plants have relied on liquid fuels and multiple open cycle reciprocating engines to provide both redundancy and the ability to load follow across a broad load range to maximize efficiency. This approach has created high electricity prices and significant negative environmental impact, especially that attributed to CO2, NOx, and SOx.

With increasing natural gas production, the availability of Liquefied Petroleum Gas (LPG) has grown, and costs have fallen, allowing the potential to switch from fuel oils to LPG to reduce environmental impacts. Energy costs and environmental impact can be further reduced by using high efficiency Gas Turbine Combined Cycle plants with dry low emissions combustion technology. However, a further hurdle facing many locations is lack of the fresh water required for combined cycle operations.

LPG-fuelled Gas Turbine Combined Cycle using Organic Rankine Cycle (ORC) technology can address all aspects of this energy trilemma. This paper reviews the conceptual design of a proposed 100MW distributed power plant for an island location, based on multiple LPG-fuelled gas turbines to follow load demand, with an ORC bottoming cycle to maximize efficiency.
Stochastic Optimization for Long Term Capital Structures, Systems, and Components Refurbishment and Replacement
Authors: Wang Congjian , Mandelli Diego , St Germain Shawn , Smith Curtis , Morton David , Popova Ivilina , Hess Stephen
Published: October 2020

As commercial nuclear power plants (NPPs) pursue extended plant operations in the form of Second License Renewals (SLRs), opportunities exist for these plants to provide capital investments to ensure long-term, safe, and economic performance. Several utilities have already announced their intention to pursue extended operations for one or more of their NPPs via SLR2. The goal of this research is to develop a risk-informed approach to evaluate and prioritize plant capital investments made in preparation for, and during the period of, extended plant operations to support decisions in NPP operations. In order to prioritize project selection via a risk-informed approach we developed a single decision-making tool that integrates safety/reliability, cost, and stochastic optimization models to provide users with data analysis capabilities to more cost effectively manage plant assets. Both stochastic analysis methods — such as Monte Carlo-based sampling strategies — and multi-stage stochastic optimization strategies are employed to provide priority lists to decision-makers in support of risk-informed decisions. We applied the proposed method to a trial application of projected replacement/refurbishment expenditures for plant capital assets (i.e., structures, systems, and components [SSCs]). The objective is to optimize the SSC replacement/refurbishment schedule in terms of economic constraints, data uncertainties, and SSC reliability data, as well to generate a priority list for maximizing returns on investment.
Study on Basic Coal Consumption Characteristics in Dynamic Process of 660MW Ultra-Supercritical Coal-Fired Unit
Authors: Yin Junjie , Liu Ming , Yan Junjie , Zhao Yongliang
Published: October 2020

With the spreading of intermittent renewable power, coal-fired power units should cycle frequently to balance the load between power supply side and demand side. Coal consumption of coal-fired units operating in dynamic processes is influenced by many factors, including thermal system, control system, heat storage variation, etc. Therefore, it is very difficult to evaluate the energy efficiency of coal-fired units operating in dynamic processes. It is important to ascertain the basic coal consumption rate in dynamic processes, which is the basis to evaluate the operation performance of coal-fired units.

In this study, an off-design calculation model of 660MW ultra-supercritical coal-fired unit is developed and validated with design parameters. The developed model can be used to predict the coal consumption rates under steady-state off-design conditions. The basic coal consumption means the coal consumption of coal-fired units with operating parameters the same as target values. To calculate the basic coal consumption rate, a load cycling process is differentiated into lots of short time periods and every period is regarded as a steady-state condition with constant load, therefore the coal consumption rates in every period are equal to that of the corresponding steady-state condition. The calculation formula of basic coal consumption rates in is derived for load cycling processes.

On the basis of the off-design calculation model and assumption of idealized condition, average coal consumption rates during different processes with constant load cycling rates can be calculated and analyzed. Results show that if the initial and final loads are both settled, the basic coal consumption rate remains unchanged and is independent of load cycling rate. If the load cycling amplitude remains unchanged, the basic coal consumption rate increases as the initial load decrease. The study aims to provide benchmark values for the energy consumption analysis in actual dynamic processes, and further study on coal consumption characteristics in dynamic processes will be developed based on it.
Thermo-Economic Analysis on Waste Heat and Water Recovery Systems of Boiler Exhaust in Coal-Fired Power Plants
Authors: Yang Kaixuan , Liu Ming , Yan Junjie
Published: October 2020

Waste heat and water recovery from boiler exhaust fluegas is significant for reducing coal and water consumption of coal-fired power plants. In this study, waste heat and water recovery system No.1 (WHWR1) and No.2 (WHWR2) were proposed with a 330MW air-cooling coal-fired power plant as the reference power plant. In these systems, boiler exhaust fluegas is cooled to 95 °C in fluegas coolers before being fed to the electrostatic precipitator. Moreover, a fluegas condenser is installed after the desulfurizer to recover water from fluegas. The recovered waste heat is used to heat the condensation water of the regenerative system, boiler feeding air and the fluegas after fluegas condenser. Then, thermodynamic and economic analyses were carried out. Heat exchangers’ areas of WHWRs are affected by heat loads and heat transfer temperature differences. For the unit area cost of heat exchangers is different, the cost of WHWRs may be decreased by optimizing multiple thermodynamic parameters of WHWR. Therefore, the optimization models based on Genetic Algorithm were developed to obtain the optimal system parameters with best economic performance. Results show that the change in coal consumption rate (Δb) is ∼ 4.8 g kW−1 h−1 in WHWR2 and ∼ 2.9 g kW−1 h−1 in WHWR1. About 15.3 kg s−1 of water can be saved and recovered when the fluegas moisture content is reduced to 8.5%. The investment of WHWR2 is higher than WHWR1, while the static recovery period of WHWR2 is shorter than that of WHWR1 for the additional Δb of pre air pre-heater.
Thermo-Economic Optimization on the Waste Heat Recovery System of SCO2 Coal-Fired Power Plants
Authors: Sun Ruiqiang , Yang Kaixuang , Liu Ming , Yan Junjie
Published: October 2020

The temperature of SCO2 fed to the boiler in SCO2 coal-fired power plants is relatively high, ∼500 °C. It leads to high boiler exhaust temperature, which is ∼120 °C according to previous studies. Waste heat recovery from low temperature fluegas in SCO2 coal-fired power plants is a key issue to be addressed to enhance power plant efficiency and electrostatic precipitator performance. Therefore, systems of waste heat recovery from low-temperature fluegas were proposed in this study. To evaluate the economic performances of the proposed systems and obtain the best system configurations, economic and thermodynamic models were developed. Moreover, multi-parameter optimization model based on Genetic Algorithm was developed. The waste heat recovery system is proposed and optimized by considering coupling and matching of the air preheating process, heat regenerative process and fluegas cooling process. With a 1000MW SCO2 coal-fired power plant as the reference case, thermodynamic and economic analyses were carried out. Results show that when the low temperature economizer is integrated together with the main compressor intercooling and flue bypass ahead the air-preheater, the temperature of exhaust fluegas can be decreased to ∼95 °C and the power plant efficiency can be enhanced by 1.39%-pts compared with basic system. Through the economic model analysis, the system levelized cost of electricity is 0.04158 $ kW−1 h−1.
A High-Power Ironless Ultra-Light Direct-Drive Wind Generator Based on Circular Flux
Authors: Zarghami Mahyar , Vann Charles , Steensnaes Frank
Published: October 2020

This paper introduces a novel type of direct-drive electric generator, suitable for producing high-power at low rpm in wind applications. The proposed patented design eliminates the magnetic core based on the concept of circular flux and characteristics of Halbach Array. By using circular flux crossing through patented Folded Electromagnetic Coils (FECs) on the stator, an optimal design with maximum use of space will be gained. Furthermore, through special configuration of diametric and axial magnets on the rotor, a pattern of circular flux can be produced, which is magnified only on the side of the stator (where needed), based on characteristics of the Halbach array. By using such design, the need for using magnets on both sides of armature windings (devised in certain designs such as the Yokeless and Segmented Armature (YASA) topology), will be eliminated, resulting in further reduction of the magnetic materials in the machine design. In the paper, we show how the proposed design results in better no-load voltage per kg by a factor of 1.52 when compared to a YASA design of the same physical size. Furthermore, we show how our calculations are based on experimental results verified through tests on a prototype of the proposed design.
Thermodynamic Analysis on a Heat-Power Decoupling System Integrated With Absorption Heat Pump
Authors: Wang Liyuan , Liu Ming , Fu Yue , Liu Jiping , Yan Junjie
Published: October 2020

Because of the continuous expanding of the district heating, the heating load of combined heat and power (CHP) plants increases year by year. The minimum power load of CHP plant increases with the heating load due to the heat-power coupling mechanism. Therefore, heat-power decoupling is necessary to improve the operation flexibility for CHP units. Integrating the absorption heat pump (AHP) is an effective method to realize the heat-power decoupling. In this study, a 330MW CHP unit model and AHP model have been developed and validated. The performance of the heat-power decoupling and energy saving performance has been investigated by comparing the thermodynamic performance indicators. Results show that, the proposed system can increase the maximum heating load and decrease the power generation when the primary network return temperature is decreased. When the heating steam extraction is kept constant, with the increase of the primary network return water temperature, the heat generation efficiency and the standard coal consumption rate of heating increases, the coal consumption rate of power generation and the heating efficiency decreases. And the primary network return water temperature increases from 40 °C to 70 °C, the coal consumption rate of power generation decreases by 4.3 g/kWh, and the coal consumption rate of heating increases by 0.67 kg/GJ.
Integration of Hydro and Renewable Energy Resources in Energy Planning
Authors: Luciano De La Cruz Lucero Cynthia , Celis Cesar
Published: October 2020

Renewable energy is the energy obtained from resources inexhaustible in the long term. Furthermore, in some countries, non-conventional renewable energy includes solar, wind, biomass, geothermal and mini-hydropower. The definition of mini-hydropower plants varies depending on the country. As an example, in Peru and Canada, mini-hydropower plants have different installing capacities, below 20MW and 50MW, respectively. Accordingly, this work (i) discusses the Energy Balance and challenges that renewable energies have to face on their way to the energy transition, (ii) highlights the forecast models to generate renewable energy in short-term energy planning. The historical data about the renewable energy resources and the energy produced have been obtained by COES. The R studio software was used for statistical analysis of renewable resources and electricity generation. Also, a forecast model was developed using a neural network to forecast renewable energy generation. The results show a strong correlation between hydro resources and non-conventional renewable energy resources. Finally, the data obtained from the renewable generation forecast model were used as input to carry out a short-term dispatch model using GAMS software to determine the forecast of daily marginal cost in SEIN.
Advancements of a Piston Engine and Electrochemical Combined Hybrid System for Unmanned Aerial Systems
Authors: Welles Thomas S. , Ahn Jeongmin
Published: October 2020

This work investigates the integration of solid oxide fuel cells (SOFCs) and a small methanol/nitromethane fueled piston engine as a prospective hybrid powertrain for small unmanned aerial systems (UASs). The increased chemical energy density of a liquid fuel when compared to traditional batteries, along with ease of storage, accessibility, and refuel time make the use of a liquid fuel powered UAS preferable when compared to battery only power UAS’.

Currently small UAS’ of increasing interest as a research area, as they have a wide application to a variety of fields. UAS’ are currently being used for precision agricultural crop management and water resource visual inspection. UAS’ are a cost effective avenue to survey water resources and track water runoff that is contaminating water resources. UAS’ can be easily automated and fitted with sensors and cameras capable of providing actionable feedback to the user. The use of UAS’ for land management and survey is expected to continue to expand. However, nearly all UAS’ are powered by a typical lithium polymer battery pack, giving an average endurance of approximately twenty minutes. This is acceptable to most hobbyists and for short filming duration; however, it limits UAS’ to only being able to be operated in close proximity to the user. Current power plants for UAS’ are not suited for long duration missions, such as the survey of water resources. Therefore, the development of a hybrid power plant is crucial for UAS’ to be utilized to their full potential as a survey tool.

This work introduces a small internal combustion engine to act as a partial oxidation fuel reformer, producing high temperature exhaust and syngas. The exhaust of this engine is then analyzed as a fuel source for tubular SOFC’s. The SOFC is integrated into the exhaust of a 3.3 cm3 nitromethane fueled two-stroke engine, achieving a maximum power of 680 mW/cm2. A theoretical comparison of flight time indicates that the modular hybrid system could increase a typical small UAS’ flight time beyond 1 hour. The system is capable of achieving a significantly higher energy density than traditional lithium polymer batteries.
Optimized Intake Manifold Designs and Their Effects on the Operation and Emissions of a Gas-to-Liquid Diesel Engine
Authors: Abdellatif Y. M. , Saker A. T. , Elbashir A. M. , Ahmed S. F.
Published: October 2020

Two simultaneous strategies have been used in this work to reduce the diesel engine emissions. First, using novel manifold designs to generate strong turbulence and improve the fuel-air mixing inside the cylinder. The second strategy is the usage of alternative fuels, namely Gas-To-Liquid (GTL) fuel and its blends with diesel fuel. In this study, six new spiral-helical manifolds designs have been tested, which could be divided into two groups. The first group is m(2.6,30,1t), m(2.6,30,2t), m(2.6,330,3t) and m(2.6,30,4t) which contains manifolds that have the same inner diameter (2.6 cm), same outlet angle (30°), but different number of spiral turns (1t, 2t..etc). The second group is m(2.1,30,3t), m(2.6,30,3t) and m(2.9,30,3t) which contains the same parameters but different inner diameters. It should be mentioned that the outlet angle of all manifolds has been tested in previous investigations [18, 52] and 30° showed the best performance.

The results of the current study showed that the highest pressure and heat release achieved by manifold m(2.6,30,1t) for the blended diesel-GTL fuel. It was observed that the heat release rate decreases with the increase in number of turns. The lowest pressure raise rate was recorded for the combination of m(2.6,30,1t) and diesel fuel. Same combination also reduced the pressure raise rate (dP/dθ) by about 24% compared to the normal manifold. The bsfc for all fuels and m(2.6,30,1t) were almost the same as the normal manifold. For the emissions, NO emissions were reduced by about 25% compared to normal manifold when m(2.6,30,4t) and GTL are used. On the other hand, the normal manifold recorded the least NO emissions for the other fuels. The manifold m(2.6,30,1t) recorded slightly higher NO emissions compared to the normal manifold for all fuels. The total particulate matters (PM) were the lowest for m (2.6,30,1t) and normal manifold in case of diesel fuel. In general, It was found that the combination of m(2.6,30,1t) with diesel fuel gave the optimum performance among all manifolds, while using m (2.6,30,4t) with GTL fuel produced low emission levels.
Numerical Study on Renewable and Sustainable Fuels for HPDF Engines
Authors: Frankl Stephanie G. , Gelner Alexander D. , Gleis Stephan , Härtl Martin , Wachtmeister Georg
Published: October 2020

Renewable and sustainable fuels (based on electricity) will play a key role in future scenarios for power supply. Enabling storage and distribution of local and temporal fluctuations of renewable energies, different e-fuels with varying production processes and characteristics get interesting for different locations. For reconversion of the chemical energy, a fuel-flexible internal combustion engine with a High Pressure Dual Fuel (HPDF) combustion process is suitable for different e-fuels. As the combustion process is the main influence on emissions, combustion behavior of the studied fuels hydrogen, methane, methanol and ammonia, ignited by the pilot fuels Fischer-Tropsch diesel and polyoxymethylene dimethyl ethers (OME), is investigated in varying fuel pairings. In addition, a review of production efficiencies and important characteristics like toxicity and storage method is given. Afterwards, the application of the investigated fuels in HPDF-combustion is investigated. The investigations are conducted with a numerical 3D-CFD model of a large bore high speed single cylinder research engine. The differences in ignition and combustion when using diesel or OME as pilot fuel are shown and a comparison of the emissions for the used main fuels is given.
A Hybrid Wind Speed Prediction Approach Based on Ensemble Empirical Mode Decomposition and BO-LSTM Neural Networks for Digital Twin
Authors: Hu Weifei , He Yihan , Liu Zhenyu , Tan Jianrong , Yang Ming , Chen Jiancheng
Published: October 2020

Precise time series prediction serves as an important role in constructing a Digital Twin (DT). The various internal and external interferences result in highly non-linear and stochastic time series data sampled from real situations. Although artificial Neural Networks (ANNs) are often used to forecast time series for their strong self-learning and nonlinear fitting capabilities, it is a challenging and time-consuming task to obtain the optimal ANN architecture. This paper proposes a hybrid time series prediction model based on ensemble empirical mode decomposition (EEMD), long short-term memory (LSTM) neural networks, and Bayesian optimization (BO). To improve the predictability of stochastic and nonstationary time series, the EEMD method is implemented to decompose the original time series into several components, each of which is composed of single-frequency and stationary signal, and a residual signal. The decomposed signals are used to train the BO-LSTM neural networks, in which the hyper-parameters of the LSTM neural networks are fine-tuned by the BO algorithm. The following time series data are predicted by summating all the predictions of the decomposed signals based on the trained neural networks. To evaluate the performance of the proposed hybrid method (EEMD-BO-LSTM), this paper conducts a case study of wind speed time series prediction and has a comprehensive comparison between the proposed method and other approaches including the persistence model, ARIMA, LSTM neural networks, B0-LSTM neural networks, and EEMD-LSTM neural networks. Results show an improved prediction accuracy using the EEMD-BO-LSTM method by multiple accuracy metrics.
Large Eddy Simulations of In-Nozzle Cavitation Phenomena for Cold Fuel Injection
Authors: Bontitsopoulos Stavros , Hamzehloo Arash , Aleiferis Pavlos G. , Cracknell Roger F.
Published: October 2020

The present work investigates the in-nozzle phenomenology of cold fuel injections. Large Eddy Simulations (LES) were performed using a 3D model of a step nozzle injector with water and iso-octane serving as working fluids and the examined cases spanning across a range of temperatures that is relevant to an engine’s start-up operation. The aim is to shed light on the influence exerted by temperature on the in-nozzle cavitation mechanism, which in turn affects the primary atomization and the structure of the downstream emerging spray.

Results suggest that a decrease in the injected fuel’s temperature induces a reduction of the nozzle’s void fraction and a shrinkage in the streamwise length of the cavitation region. This suggests that the size and intensity of the hydrodynamic cavitation features tend to become suppressed in cold conditions. The phenomenon appears to be driven by the temperature dependence of the injected fluid’s thermophysical properties, primarily the vapour pressure, with lower values hindering phase change.
Thermodynamic Analysis for Cogeneration CSP-MED Cycle Using sCO2 and Sensible Heat Sources
Authors: Caceres Gonzalez Rodrigo A. , Hatzell Marta C.
Published: October 2020

Here we perform a steady state thermodynamic analysis of a cogeneration cycle capable of producing power through a supercritical Carbon Dioxide (sCO2) recompression Brayton cycle and water through a Multi Effect Distillation (MED) plant. The integration considers a demineralized water loop heated by rejected sCO2. Thus, the performance of the power block is independent of the desalination block. Each block of the system is independently analyzed to identify the operational or design parameters that influence the thermodynamic efficiency and water and power production. For a power block producing 112.6 MW, with a fixed turbine inlet temperature, the pressure ratio (PR) is the most influential variable in order to maximize net power production and thermal efficiency. For the desalination block, producing 2659 m3/d of water, the last effect temperature (TN) is the most influential variable for water production. In the integrated cogeneration system, increasing PR beyond the power block optimized value (From PR = 3.5 to 3.96) reduces power (from 112.6 to 112.4 MW), but increases water production (from 35 to 40 kg/s), and decreases the specific energy consumption from 29.4 kWh/m3 of water to 26.5 kWh/m3 of water.
Reactor Network Modeling of Stability and Emissions of Hydrogen and Natural Gas Blends for a Piloted Gas Turbine Combustor
Authors: Hernandez Candy , McDonell Vincent
Published: October 2020

Lean-premixed (LPM) gas turbines have been developed for stationary power generation in efforts to reduce emissions due to strict air quality standards. Lean-premixed operation is beneficial as it reduces combustor temperatures, thus decreasing NOx formation and unburned hydrocarbons. However, tradeoffs occur between system performance and turbine emissions. Efforts to minimize tradeoffs between stability and emissions include the addition of hydrogen to natural gas, a common fuel used in stationary gas turbines. The addition of hydrogen is promising for both increasing combustor stability and further reducing emissions because of its wide flammability limits allowing for lower temperature operation, and lack of carbon molecules. Other efforts to increase gas turbine stability include the usage of a non-lean pilot flame to assist in stabilizing the main flame. By varying fuel composition for both the main and piloted flows of a gas turbine combustor, the effect of hydrogen addition on performance and emissions can be systematically evaluated. In the present work, computational fluid dynamics (CFD) and chemical reactor networks (CRN) are created to evaluate stability (LBO) and emissions of a gas turbine combustor by utilizing fuel and flow rate conditions from former hydrogen and natural gas experimental results. With CFD and CRN analysis, the optimization of parameters between fuel composition and main/pilot flow splits can provide feedback for minimizing pollutants while increasing stability limits. The results from both the gas turbine model and former experimental results can guide future gas turbine operation and design.
Pilot-Scale System With Particle-Based Heat Transfer Fluids for Concentrated Solar Power Applications
Authors: Bonino Christopher A. , Hlebak Joshua , Baldasaro Nicholas , Gilmore Dennis
Published: October 2020

Concentrated solar power (CSP) is a promising large-scale, renewable power generation and energy storage technology, yet limited by the material properties of the heat transfer fluid. Current CSP plants use molten salts, which degrade above 600°C and freeze below 220°C. A dry, particle-based heat transfer fluid (pHTF) can operate up to and above 1,000°C, enabling high-efficiency power cycles, which may enhance CSP’s commercial competitiveness. Demonstration of the flow and heat-transfer performance of the pHTF in a scalable process is thereby critical to assess the feasibility for this technology.

In this study, we report on a first-of-a-kind pilot system to evaluate heat transfer to/from a densely flowing pHTF. This process unit circulates the pHTF at flowrates up to 1 tonne/h. Thermal energy is transferred to the pHTF as it flows through an electrically heated pipe. A fluidization gas in the heated zone enhances the wall-to-pHTF heat transfer rate. We found that the introduction of gas mixtures with thermal conductivities 4.6 times greater than that of air led to a 65% increase in the heat transfer coefficient compared to fluidization by air alone. In addition to the fluidization gas, the particle size also plays a critical role in heat transfer performance. Particles with an average diameter of 270 μm contributed to heat transfer coefficients that were up to 25% greater than the performance of other particles of the same composition in size range of 65 to 350 μm. The considerations for the design of an on-sun system are also discussed. Moreover, the collective work demonstrates the promise of this unique design in solar applications.
Investigation of Soot Formation in Fuel-Rich Premixed Propane/Air Microcombustion at Low Temperatures
Authors: Khalid Abdul H. , Tian Jiashen , Skabelund Brent B. , Milcarek Ryan J.
Published: October 2020

The advantage of micro/meso combustion includes higher efficiency, improved heat and mass transfer, swift startup and shutdown when compared with regular combustion. This study aims to investigate the critical sooting equivalence ratio and soot precursor formation in a micro-flow reactor with a controlled temperature profile of diameter 2.3mm and their dependence on the temperature ranging from 800–1250 °C. The equivalence ratio is varied from 1–13 and flow rates of 10 and 100sccm were investigated. Also, nitrogen is used to study the effect of inert gas dilution. A gas chromatograph is used to study the exhaust gas composition. The reactor is analyzed visually for the traces of soot particles before and after combustion, each time the temperature and/or equivalence ratio is varied. From 750–950°C, no soot is indicted at all equivalence ratios even up to 100. The inert gas dilution helped in raising the critical sooting equivalence ratio as expected because of the lower temperature. The results indicated an opposite trend to what has been well understood for the pre-mixed sooting flames, i.e., decreasing temperature decreases soot formation. The capability of the reactor to examine the effects of temperature on the critical sooting equivalence ratio at different flow rates has been successfully demonstrated.