bluuebunny/crossref_metadata_2025 huggingface dataset:
Risk factors of anaemia and iron deficiency in Somali children and women: Findings from the 2019 Somalia Micronutrient Survey
Authors: Wirth James P. , Sesay Fatmata , Mbai Joshua , Ali Sundus Ibrahim , Donkor William E. S. , Woodruff Bradley A. , Pilane Zahra , Mohamud Kheyriya Mohamed , Muse Ahmed , Yussuf Hamda Omar , Mohamed Warsame Said , Veraguth Rosmarie , Rezzi Serge , Williams Thomas N. , Mohamoud Abdullahi Muse , Mohamud Farhan Mohamed , Galvin Melanie , Rohner Fabian , Katambo Yvonne , Petry Nicolai
Published: August 2021

There are limited data on the prevalence of anaemia and iron deficiency (ID) in Somalia. To address this data gap, Somalia's 2019 micronutrient survey assessed the prevalence of anaemia and ID in children (6–59 months) and non‐pregnant women of reproductive age (15–49 years). The survey also collected data on vitamin A deficiency, inflammation, malaria and other potential risk factors for anaemia and ID. Multivariable Poisson regressions models were used to identify the risk factors for anaemia and ID in children and women. Among children, the prevalence of anaemia and ID were 43.4% and 47.2%, respectively. Approximately 36% and 6% of anaemia were attributable to iron and vitamin A deficiencies, respectively, whereas household possession of soap was associated with approximately 11% fewer cases of anaemia. ID in children was associated with vitamin A deficiency and stunting, whereas inflammation was associated with iron sufficiency. Among women, 40.3% were anaemic, and 49.7% were iron deficient. In women, ID and number of births were significantly associated with anaemia in multivariate models, and approximately 42% of anaemia in women was attributable to ID. Increased parity was associated with ID, and incubation and early convalescent inflammation was associated with ID, whereas late convalescent inflammation was associated with iron sufficiency. ID is the main risk factor of anaemia in both women and children and contributed to a substantial portion of the anaemia cases. To tackle both anaemia and ID in Somalia, food assistance and micronutrient‐specific programmes (e.g. micronutrient powders and iron supplements) should be enhanced.
Shugoshin ensures maintenance of the spindle assembly checkpoint response and efficient spindle disassembly
Authors: Sane Aakanksha , Sridhar Shreyas , Sanyal Kaustuv , Ghosh Santanu K.
Published: August 2021

Shugoshin proteins are evolutionarily conserved across eukaryotes, with some species‐specific cellular functions, ensuring the fidelity of chromosome segregation. They act as adaptors at various subcellular locales to mediate several protein‐protein interactions in a spatio‐temporal manner. Here, we characterize shugoshin (Sgo1) in the human fungal pathogen Candida albicans. We observe that Sgo1 retains its centromeric localization and performs its conserved functions of regulating the sister chromatid biorientation, centromeric condensin localization, and maintenance of chromosomal passenger complex (CPC). We identify novel roles of Sgo1 as a spindle assembly checkpoint (SAC) component with functions in maintaining a prolonged SAC response by retaining Mad2 and Bub1 at the kinetochores in response to improper kinetochore‐microtubule attachments. Strikingly, we discover the in vivo localization of Sgo1 along the length of the mitotic spindle. Our results indicate that Sgo1 performs a hitherto unknown function of facilitating timely disassembly of the mitotic spindle in C. albicans. To summarize, this study unravels a unique functional adaptation of shugoshin in maintaining genomic stability.
Prediction of hand‐wrist maturation stages based on cervical vertebrae images using artificial intelligence
Authors: Kim Dong‐Wook , Kim Jinhee , Kim Taesung , Kim Taewoo , Kim Yoon‐Ji , Song In‐Seok , Ahn Byungduk , Choo Jaegul , Lee Dong‐Yul
Published: August 2021

Objective

To predict the hand‐wrist maturation stages based on the cervical vertebrae (CV) images, and to analyse the accuracy of the proposed algorithms.

Settings and population

A total of 499 pairs of hand‐wrist radiographs and lateral cephalograms of 455 orthodontic patients aged 6‐18 years were used for developing the prediction model for hand‐wrist skeletal maturation stages.

Materials and Methods

The hand‐wrist radiographs and the lateral cephalograms were collected from two university hospitals and a paediatric dental clinic. After identifying the 13 anatomic landmarks of the CV, the width‐height ratio, width‐perpendicular height ratio and concavity ratio of the CV were used as the morphometric features of the CV. Patients’ chronological age and sex were also included as input data. The ground truth data were the Fishman SMI based on the hand‐wrist radiographs. Three specialists determined the ground truth SMI. An ensemble machine learning methods were used to predict the Fishman SMI. Five‐fold cross‐validation was performed. The mean absolute error (MAE), round MAE and root mean square error (RMSE) values were used to assess the performance of the final ensemble model.

Results

The final ensemble model consisted of eight machine learning models. The MAE, round MAE and RMSE were 0.90, 0.87 and 1.20, respectively.

Conclusion

Prediction of hand‐wrist SMI based on CV images is possible using machine learning methods. Chronological age and sex increased the prediction accuracy. An automated diagnosis of the skeletal maturation may aid as a decision‐supporting tool for evaluating the optimal treatment timing for growing patients.
What are patients' beliefs about, and experiences of, adaptation to glasses and how does this affect their wearing habits?
Authors: Hughes Amy , Fylan Fiona , Elliott David B.
Published: August 2021

Purpose

It is well known that some patients experience difficulties adapting to new glasses. However, little is known about what patients themselves understand of the adaptation process, and how this influences their attitudes and the decisions they make when adapting to a new pair of glasses. Nor is it understood whether these factors affect their wearing habits.

Methods

We conducted four focus groups. Participants were 22 glasses wearers (mean ± SD age 43 ± 14 years, range 21–71 years) who reported they: (1) wore spectacle correction for distance vision (single vision, bifocal or progressive lenses); (2) had struggled to get used to a new pair of glasses and (3) sometimes chose not to wear their distance correction. Focus groups were audio recorded, transcribed verbatim and analysed thematically.

Results

We identified three themes. Trust is about how participants' trust in their optometrist and themselves influences the likelihood of them adapting successfully to new glasses. Conflict describes how the advice patients have received about adapting to glasses can conflict with what they have experienced and how this conflict influences their expectations. Part of Me explores how participants' experiences and feelings about their glasses are important to adaptation and this includes physical, visual, emotional and behavioural aspects.

Conclusions

The traditional optometric perspective of adaptation to glasses is much narrower than that held by patients, and significantly underestimates the physical, behavioural and emotional adaptation that patients must go through in order to feel fully comfortable wearing their glasses. Patients should receive significantly more information about adaptation, including symptoms that may be experienced and why these happen, practical tips to aid adaptation, and when and how to raise concerns. Patients should also receive information about the day‐to‐day effects of blur adaptation to avoid them not wearing their glasses, including for vision‐critical tasks such as driving.
Comparison of the value of immature retyculocyte and immature platelet in the diagnosıs of sepsis
Authors: Türkmen Dilek , Özsoylu Serkan , Akyıldız Başak Nur
Published: August 2021

Background

Sepsis is one of the causes of pre‐treatment morbidity and mortality in the pediatric age group. In the present study, we investigated the place of the immature granulocyte percentage, (IG) immature reticulocyte fraction (IRF), and immature platelet fraction (IPF) in the diagnosis of sepsis.

Methods

Complete blood count, C‐reactive protein, (CRP) procalcitonin (PCT) and blood cultures were measured in 125 critical patients who were followed‐up in the intensive care unit with the suspicion of sepsis and 65 healthy children between 2017 and 2019. In addition to the complete blood counts and routine parameters, IG, IRF, and IPF were examined in the patients.

Results

When the critical patient group and the healthy control group were compared, it was found that the total number of leukocytes (white blood cells), neutrophil count, platelet count, CRP, PCT, IG, IRF, and IPF values were higher at statistically significant levels. When septic and non‐septic patients were compared, it was found that the CRP, PCT,IGP, and IPF were higher at statistically significant levels in the septic patients.

Conclusions

It was concluded that CRP, PCT, IG, and IPF were significant in determining sepsis and that PCT was the most sensitive and specific biomarker in these parameters. We believe that these parameters may be suitable for practical use in determining sepsis because they give faster results and suggest the diagnosis of sepsis.
Molecular insights into enhanced resistance of Papaver somniferum against downy mildew by application of endophyte bacteria Microbacterium sp. SMR1
Authors: Ray Tania , Pandey Alok , Pandey Shiv S. , Singh Sucheta , Shanker Karuna , Kalra Alok
Published: August 2021

Downy mildew is one of the most serious diseases of Papaver somniferum. Endophytes isolated from different parts of P. somniferum were screened for their ability to enhance resistance against downy mildew caused by the obligate biotrophic oomycete Peronospora meconopsidis. Two endophytes (SMR1 and SMR2) reduced the downy mildew on three P. somniferum genotypes (Sampada, J‐16, and I‐14). SMR1 (Microbacterium sp.) also enhanced the resistance of P. somniferum against downy mildew under field conditions. The biochemical markers of plant susceptibility under biotic stresses (proline and malondialdehyde) were found to be reduced in P. somniferum upon SMR1 treatment. To understand the mechanisms underlying the enhanced resistance to downy mildew in SMR1 endophyte‐treated P. somniferum genotype J‐16, we compared the expression profiles using the next‐generation RNA sequencing approach between P. somniferum pretreated with SMR1 and untreated endophyte‐free control plants following exposure to downy mildew pathogen. Comparative transcriptome analysis revealed differential expression of transcripts belonging to broad classes of signal transduction, protein modification, disease/defense proteins, transcription factors, and phytohormones in SMR1‐primed P. somniferum after infection with downy mildew pathogen. Furthermore, enhanced salicylic acid content was observed in SMR1‐primed P. somniferum after exposure to downy mildew pathogen. This study sheds light on molecular mechanisms underlying enhanced resistance to downy mildew in SMR1‐primed P. somniferum. Finally, we propose that the SA‐dependent defense pathway, the hallmark of systemic acquired resistance, is activated in SMR1‐primed P. somniferum, triggering the endophyte‐induced resistance.
The obscure divine: Ambivalence in the Ethiopian Orthodox Church
Authors: de Ménonville Siena‐Antonia
Published: August 2021

This article presents a look at contemporary research on Orthodox Christianity in Ethiopia while specifically examining the controversialdebtera. Thedebtera, who figure among the Ethiopian Orthodox Church clergy preforming both Orthodox and occult services, are a telling societal phenomenon. This article should not be read strictly as a summary of the academic literature of the Ethiopian Orthodox Church, but rather it introduces a new category—“debteric studies”—in the hopes of expanding the limits of existing research in the field as well as by calling attention the cultural relevance of the duality that thedebteraembody. While tracking the trajectory of “debteric studies”, a discourse on secrecy, knowledge, and ambivalence also emerges. Studying thedebterareveals that he both incites rules and the transgression of those rules. He is considered to be on the margins of Ethiopian society, but, at the same time, his presence and the need for his capabilities remains ubiquitous. This article argues that furthering “debteric studies” may also contribute more generally to the study of ambivalence within religious structures.
A produção de alimentos básicos: reestruturação regional?
Authors: Hoefle Scott William
Published: August 2021

The evolution of development policy and the behavior of farm prices is related to change in the production of the traditional staples beans, manioc, maize and rice during three distinct periods: 1940-1964, 1964-1979 and 1979 to date. From 1940 onward staple production in the economic heartland of Brazil came under increasing pressure from expanding export and agroindustrial production on one hand and from discriminatory pricing policy on the other. In response to this pressure staple farmers in the South, Southeast and more recently in the Central-West increased productivity through flexible capitalization. Production continued to expand in these regions so that they still dominate the national market for beans, maize and rice. At the same time horizontal expansion of food production on the distant frontier proved to be insignificant and fell drastically in the depressed peripheral Northeast region disproving theses which attribute staple production to pre-capitalist peasant farmers of these regions.
"Urbanofilia" e "urbanofobia" na geopolítica: as cidades e a urbanização no pensamento geopolítico alemão do entre-guerras e na geopolítica brasileira do regime de 64
Authors: Souza Marcelo José Lopes de
Published: August 2021

This paper results from two short sections of the author's PhD thesis. The main purpose of this article is to focus a subject almost unknow in Brazil: The view of the German geopoliticians of the 30s on the urbanization and the cities, in relation to the thought of the German geographer Friedrich Ratzel and the Brazilian geopolitics during the military rule. One can only understand the "urbanophilia" of Ratzel, the "urbanophobia" of the German geopoliticians, and the more complex view of the Brazilian geopolitics of the Post-64 period, within their respective sociohistorical contexts. Despite there are doctrinal similarities among Ratzel's work and the thought of German geopoliticians of the 30s, and among the German geopoliticians and the Brazilian geopolitics of the Post-64 period, the different socio-historical situations explain the different views in relation to the urbanization and its significance in terms of "progress" and "development".
Aloestratigrafia e análise de fácies: "revoluções" na geologia sedimentar e o estudo do quaternário
Authors: Mello Claudio Limeira
Published: August 2021

A conceptual discussion is presented concerning some important aspects of the modern sedimentary geology as they are related to particularities of the Quaternary sedimentary record. This study intends to provide new elements for a most objective analysis of Quaternary deposits. The approach utilized is based on the purpose to integrate stratigraphie and sedimentologic analysis. The allostratigraphic perspective and the faciologic analysis of events are hereby recommended. The association of geomorphology and stratigraphy is also emphasized as a basic aspect to studies of Quaternary deposits. Concerning this aspect, the identification of depositional surfaces is particularly important.
Os 40 anos da CAGE: Campanha Nacional de Formação de Geólogos, os cursos de geologia no Brasil e, em particular, no Rio de Janeiro
Authors: Barroso Josué Alves
Published: August 2021

Celebrating the 40 years of CAGE-Campanha Nacional de Formação de Geólogos, a historical retrospective is presented since begining of Rio de Janeiro undergraduate course in geology. The achievements and its importance on technological and scientific brazilian earth sciences community are commented. Despite a vigorous past, there are difficulties at present, mainly as a result of staff decreasing. The foundation of College of Geology was already approved by Conselho Universitários and must be carried out in order to ransom the past.
Redes e sistemas do tráfico de drogas no Rio de Janeiro: uma tentativa de modelagem
Authors: Souza Marcelo Lopes de
Published: August 2021

Undoubtedly, most of the drug trade for local consumption in Rio de Janeiro is organized by quadrilhos (gangs) based in fovelas (shanty-towns), which are linked to different criminal organizations or networks (comandos). The most important criminal network of Rio de Janeiro, the Comando Vermelho (Red Commando) was created in the late 1970s. However, the mass media tend to give a false image of drug traffic and its structure. Although newspapers and television paaa the idea that the leaders of the drug traffic in the favelas are very powerful, they are to a considerable extent only the underlings of the drug trade's real sponsors, who have connection with important politicians, businessmen etc.; the most important traffickers, who operate at the level of the import/export/wholesale trade system, do not live in shanty-towns. Furthermore, the criminal organizations, which operate in the context of local retail trade (retail trade system), are not very centralized: the Comando Vermelho itself, whose founders are dead or in jail, is today essential)' a unstable solidarity network among inmates.
Enchentes no Rio de Janeiro: efeitos da urbanização no Rio Grande (arroio fundo) - Jacarepaguá
Authors: Ferreira Francisco Pontes de Miranda , Cunha Sandra Baptista da
Published: August 2021

Human participation as an agent in the modification of hydrologie conditions in urban areas has a direct relation with the processes of erosion, deposition and transport of material in river channels. Engineering work as deepening and rectification of the channel and modification in the surrounding vegetation, cause important impacts. The urban development of Jacarepagua and Barra da Tijuca districts has been causing alterations in the Grande river drainage system. In February of 1996, the flooding of the Grande river provoked more than 30 deaths, leaving hundreds of people homeless.
Electrochemical Defect Analysis of Additive Manufactured Components
Authors: Sous Florian , Herrig Tim , Bergs Thomas , Karges Florian , Feiling Nicole , Zeis Markus
Published: August 2021

Due to more freedom in design and flexibility in production, parts produced by additive manufacturing (AM) technologies offer a huge potential for the manufacture of turbomachinery components. Because of the layer by layer built structure, internal defects such as cracks or gaseous pores can occur. These defects considerably reduce the mechanical properties and increase the importance of quality control, especially in the field of turbomachinery. Therefore, in this study, an electrochemical defect analysis (EC-D) of additive manufactured components is introduced, performed, and validated in comparison to a nondestructive X-ray testing of the same part. A test rig was developed, which allows an alternation between electrochemical machining and subsequent optical documentation of each removed layer. The documentation of the surface and the macroscopic defects in the AM-parts are captured by an integrated camera system.
Impact of Hydrogen Addition on the Thermoacoustic Instability and Precessing Vortex Core Dynamics in a CH4/H2/Air Technically Premixed Combustor
Authors: Datta Anindya , Gupta Saarthak , Chterev Ianko , Boxx Isaac , Hemchandra Santosh
Published: August 2021

We study the impact of H2 enrichment on the unsteady flow dynamics and thermoacoustic instability in the prediction and control of instabilities in industrial turbines (PRECCINSTA) swirl combustor. The experiments were performed at atmospheric conditions with H2/CH4 fuel mixtures at a global equivalence ratio of 0.65 and a constant thermal power of 20 kW. We analyze data with three fuel compositions: 0%, 20%, and 50% H2 in two operating modes, premixed (PM) and technically premixed (TPM). A new multiresolution modal decomposition method, using a combination of wavelet transforms and proper orthogonal decomposition (WPOD) is performed on time resolved flow velocity and OH planar laser induced fluorescence (OH planar laser induced fluorescence (OH-PLIF)) measurements. Thermoacoustic oscillations are observed in the TPM operating mode alone, indicating that the primary heat release driving mechanism is due to fuel-air ratio oscillations. WPOD results for the 0% H2 TPM case reveal intermittent helical precessing vortex core (PVC) oscillations along with axisymmetric hydrodynamic flow oscillations due to the thermoacoustic oscillations. These oscillations cause local flame extinction near the nozzle centerbody resulting in liftoff. A PVC then develops in the flow and enables intermittent flame reattachment. In the 0% H2 premixed case, the flame remains lifted off the centerbody despite the presence of PVC oscillations. H2 enrichment results in the suppression of flame liftoff and the PVC in both operating modes. We show from flow strain rate statistics and extinction strain rate calculations that the increase of the latter with H2 addition, allows the flame to stabilize in the region near the centerbody where the pure CH4 cases show lift off.
Numerical Simulation of Resistance Sintering of Titanium by a Porous Continuum Approach
Authors: Cannella E. , Martins P. A. F. , Nielsen C. V.
Published: August 2021

This paper presents a numerical model for the simulation of resistance sintering. It involves an electro-thermo-mechanical coupling, where each model is simulated as a continuum with the influence of porosities included through the distribution of relative density, i.e., the ratio of the apparent density to that of the corresponding fully dense bulk material. For the mechanical response, this involves a plasticity model based on a porous formulation. Other material data have to be supplied as a function of relative density and temperature, as, for example, the electrical resistivity. The numerical modeling is compared to experimentally resistance sintered titanium with good agreement in terms of pre-compaction and developed relative density and temperature during the sintering process.
Development of an Actuator Line Model for Simulation of Floating Offshore Wind Turbines
Authors: Arabgolarcheh Alireza , Benini Ernesto , Anbarsooz Morteza
Published: August 2021

This study focuses on developing and applying an actuator line model (ALM) to predict the wake behind floating offshore wind turbines (FOWTs). A computational method is presented which implements an ALM, able to handle 6 Degree-of-Freedom (DOF) motion dynamics, coupled with a CFD solver. Computational grides used are cubic and do not require a boundary layer mesh. Results show that just about 300k grids are necessary for performance assessment of the NREL Phase VI case. Therefore, the proposed method leads to significantly lower computational cost and easier preprocessing compared to high-order methods used for solving RANS. On the other hand, coupled aerodynamic and motion analyses showed that pitch and surge motions have the most considerable influence on turbine performance due to their inherent effect on 3D local wind inclination in the relative frame. The peak power happened when the platform is in its initial position, where the platform motion velocity is maximum. Finally, it is shown that the wind turbine movement has a considerable effect on its wake characteristics. The gap distances between wake rings can also change wake interactions, and, for the case with platform pitch motion, the condition of the wake is even more complicated as such distance is not the same in all azimuthal sectors. The results show that the applied ALM method is beneficial for simulating the wake behind offshore wind turbines and the complex phenomena in the wake due to platform oscillation.
Experimental Evaluation of Dewar Volume and Cryocooler Cold Finger Size in a Small-Scale Stirling Liquid Air Energy Storage (LAES) System
Authors: Swanson Howard M. , Pollman Anthony G. , Hernandez Alejandro
Published: August 2021

This paper uses an experimental approach to evaluate two design characteristics for a liquid air energy storage (LAES) and generation system as part of the design analysis for a microgrid power system. The system evaluated utilized a Stirling engine based cryocooler that employs a coldfinger placed into a Dewar. Using a design of experiments, the cold finger surface area and Dewar volume were evaluated to determine the criticality and significance of changing their dimensions. Evaluations were made against the total liquid air production mass and average liquid air production rate during the experiments. This analysis found that changing the surface area of the cryocooler cold finger was a statistically significant design characteristic that affected total liquid air production and average production rate while changing the volume of the Dewar was not statistically significant. Additional responses relative to the time when the first gram of liquid air was produced and the minimum cold tip temperature that the cryocooler was able to achieve provided additional insight into design characteristics that can be used to inform the engineer when making design tradeoffs for specific operational environments.
Optimization of the Capacities of Private Generators Installed in a Hospital Building Under the Constraint of Demand Sufficiency During Power Outages
Authors: Uemichi Akane , Kaito Naoki , Yamasaki Yudai , Kaneko Shigehiko
Published: August 2021

It is essential to secure energy sources by installing a private power generator for business continuity in a power outage. The authors have developed an optimization tool to estimate the optimal amount of distributed power supply equipment using economic efficiency and resilience as two evaluation indicators. However, it is questionable whether the private generator in a hospital building can generate sufficient electricity to meet demands in case of a power failure, because demand has short cycle fluctuations on the order of seconds, and the private generator must respond to these fluctuations from time to time in the case of stand-alone operation. The optimization tools we have developed in the past have not considered the balance between power output and load demand (demand sufficiency). Therefore, this paper proposes a new optimization method that considers balancing power supply and demand in private generators’ independent operation during power outages. We narrowed the optimization constraints as demand sufficiency conditions: standard AC frequency range between 49 and 51 Hz. More practical optimal solutions are obtained by applying the new constraints to the multi-optimization. We also compare the case study results by applying these constraints to the results of previous case studies.
Common Mode Current Effects and Challenges for Wind Turbine Generator Application
Authors: Singh Gopal , Sundaram Kalpathy
Published: August 2021

Operation of the generator with full converter and long tower cables leads to common mode and bearing current in the wind turbine. Common mode and bearing current are almost always present in such systems, due to the harmonics reflections within large tower cables. An electrical system should be carefully designed to perform in such environments. Bearing insulation thickness should be carefully chosen to minimize the impact of bearing current. Ideally these currents should flow through the dedicated path within the nacelle and pass through the tower to the ground. Due to complex structure of the nacelle in the onshore geared turbine and dealing with a very high frequency current, this is usually not the case. A complex cable routing and formation of different conducting path leads the common mode current to flows into an unexpected direction. It is the part of a good system design to monitor the path and evaluate the potential impact on the sensitive components to avoid potential failure in the field. A higher downtime of the turbine corresponds to a less reliable turbine, this is also closely associated with the levelized cost of electricity. This paper presents an overview of the system for the preferred common mode current routing and recommend various method by which formation of unwanted grounding loops can be avoided.
Enginuity’s Combined Heat and Power (CHP) System Part 1: Fundamental Design & Performance Evaluation of Residential Engine System
Authors: Bade Mehar , Meyers Vince , Suits Eric , Mannarino Anthony F. , Subramanian Jayaram
Published: August 2021

The development of highly compact and energy-efficient systems is critical for world energy security and technology leadership. Due to the abundance of natural gas, the natural gas fueled distributed energy systems that lower the energy consumption and utility costs would be ideal in the U.S. as well as worldwide markets. To meet these objectives, researchers from Enginuity Power Systems (EPS) are currently working on the development of an ultra-efficient Combined Heat and Power (CHP) system for residential and commercial applications. These CHP systems generate electricity at the point of use while also meeting the space and water heating demands. Furthermore, a single CHP system replaces the conventional electricity generator, space, and water heating systems in residential and commercial applications. The main technical objective of this research article is the demonstration of the fundamental design and performance characteristics of an EPS’s 6 kW–10 kW CHP system intended for residential applications. The proposed residential system utilized a mirror-balanced, patented, inwardly opposed piston, four-stroke internal combustion engine as a prime mover. This novel four-stroke opposed piston design resolved the scavenging, cooling, and lubrication issues faced by the conventional opposed designs in the market while also maintaining the power density, balancing, and performance benefits. Initially, a series of experiments were conducted on the proposed system for different speeds and throttle openings. Later, the combustion, performance, and quantified energy loss pathways were presented at Wide Open Throttle (WOT) conditions to demonstrate the performance benefits of the proposed system. Finally, a performance-oriented framework was developed for the proposed CHP system for future efforts.
Air-Argon-Steam or Organic Fluid Combined Power Cycle With Pulse Detonation Combustion for Electric Power Plants
Authors: Nageswara Reddy Pereddy
Published: August 2021

Gas turbine engines with pulse detonation combustion show the superior performance in terms of specific work output and thermal efficiency when compared to the conventional gas turbine engines with isobaric combustion. But, a quasi-steady expansion of detonation products through the gas turbine results in an unsteady operation. Moreover, as the detonation products during quasi-steady expansion are initially at a very high temperature (over 2500 K), they cannot be expanded in the turbine as it is. To overcome the above difficulties associated with pulse detonation combustion in gas turbine engines, Air-Argon-Steam or organic fluid Combined Cycle (AASCC) is proposed in the present work. AASCC comprises two gas turbine cycles, viz. the Humphrey cycle with the air as the working fluid and the Brayton cycle with the argon as the working fluid and a steam turbine cycle, viz. the Rankine or organic Rankine cycle with the steam or organic substance as the working fluid. The temperature of the hot detonation products is reduced to Turbine Inlet Temperature (TIT) by exchanging heat energy between detonation products and compressed argon in a Detonation Products to Argon Heat Exchanger (DPAHE) and in turn, raising the temperature of the compressed argon to Argon Turbine Inlet Temperature (ATIT). The residual energy of both detonation products and argon after the expansion in the respective turbines is utilized to generate the steam or organic fluid vapor in the Heat Recovery Generators (HRGs) to operate a steam or organic fluid turbine. AASCC with pulse detonation combustion is analyzed based on quasi-steady state one dimensional formulation, and a computer code is developed in MATLAB to simulate the cycle performance at different compressor pressure ratios and TITs. C2H4/air is taken as the fuel-oxidizer. The performance of AASCC with pulse detonation combustion is compared with that of a conventional Air-Steam Combined Cycle (ASCC) with constant pressure combustion. It is found that the thermal efficiency of AASCC with pulse detonation combustion can go up to 44.5%–46.5% depending on the working fluid used in the bottoming Rankine cycle as against 37.8%–41.0% of ASCC at a TIT of 1400 K. The maximum specific work output of AASCC at a TIT of 1400 K is found to vary from 1143.0 to 1202.0 kJ/kg air as against to 335.0 to 364.0 kJ/kg air of ASCC.
Investigation of the Performance of Air-Steam Combined Cycle for Electric Power Plants Using Low Grade Solid Fuels
Authors: Nageswara Reddy Pereddy
Published: August 2021

Since the solid fuels like coal produce a lot of ash upon burning, the products of combustion can’t be expanded as it is in a Gas Turbine (GT). Hence, the operation of a combined cycle with solid fuels includes: (i) production of syngas from the coal to operate a gas turbine engine and (ii) using the leftover coal after gasification to produce steam and operate a steam turbine engine. To avoid the coal-gasification and to use the solid coal fuel as it is in a combined cycle power plant, a novel Air-Steam Combined Cycle (ASCC) is proposed in the present work. ASCC comprises a gas turbine cycle (operating by the Brayton cycle) with the air as the working fluid and a steam turbine cycle (operating by the Rankine cycle) with the steam as the working fluid. A fraction F of the air is compressed, regenerated and finally heated to an Air Turbine Inlet Temperature (ATIT) by the hot products of combustion produced upon burning of the bituminous coal in a combustor. The residual heat energy of products of combustion is then utilized in a Heat Recovery Steam Generator (HRSG) to generate the steam initially and subsequently to preheat the remaining fraction (1-F) of the air. After expansion in an air turbine, the hot air passes through a regenerator directly into a combustor along with the preheated air for burning the coal so as to utilize the energy of expanded air completely. ASCC is analyzed based on the first and second laws of thermodynamics and a computer code is developed in MATLAB to simulate the cycle performance at different compressor pressure ratios, ATITs, and HRSG pressures. The performance of ASCC is compared with that of Baseline Steam Turbine Cycle (BSTC) for the same flue gas (stack) temperature. It is found that the overall thermal efficiency of ASCC can go up to 33.0%–37.5% depending on the compressor pressure ratio, ATIT and HRSG pressure as against to 29.0%–29.5% of BSTC.
Steam Inlet Expansion Joint Design & Case Study: Surface Condenser Application
Authors: Squires Kevin
Published: August 2021

This paper is comprised of three sections and outlines the outcome achieved from instituting an effective preventative maintenance program; specifically, highlighting a steam surface condenser application that was originally equipped with a stainless-steel metal bellows type expansion joint system. In the first section of the paper, a general overview of steam inlet type expansion joint systems will be presented to provide an understanding of the specific application, typical design parameters and conditions, system components, varying expansion joint designs, configurations, and installation methodologies. The second section will outline types of inspections that typically support preventative maintenance programs within the power generation industry. Lastly, the case study will examine the account of an actual project and the practice of implementing a preventative maintenance program; outlining inspection types, how those measures supported a root cause analysis, and ultimately developing a unique solution to address the issues identified during subsequent inspections and analyses. The case study focuses on developing a retrofitted rubber ‘dog bone’ expansion joint system to replace the failed metal bellows expansion joint. Various points within the overall project life cycle will be reviewed; from the point of initial inspection that identified the root cause and defined loss in performance, evaluation and engineering to support the replacement design, onsite execution and installation methodology, and post-maintenance testing and operation.
Numerical Simulation of the Effect of Magnetic Fields on Soot Formation in Laminar Non-Premixed Flames
Authors: Chukwuemeka Edison E. , Schoegl Ingmar M.
Published: August 2021

Characteristics of non-premixed flames such as flame height and lift-off height are affected by the presence of magnetic fields due to the paramagnetic properties of some combustion species. However, it is unknown whether magnetic fields can be used to reduce the emission of pollutants in non-premixed flames.

In general, pollutant emissions are reduced in combustion systems if the mixing of combustion species is enhanced during the process. Since paramagnetic combustion species such as O2, O, OH, HO2, etc have a preferential motion direction in the presence of magnetic fields, there is a potential to harness this effect of mixing by imposing a magnetic field on the flame.

This study seeks to provide some insights on the effect of magnetic field on pollutants generated in a laminar non-premixed flame numerically. The non-premixed flame is simulated using a detailed chemical mechanism for propane-air combustion and a modified Moss-Brookes soot model. To simulate the effect of magnetism on the paramagnetic chemical species, the species paramagnetic susceptibility is computed using the Curie relation. The non-premixed flame is placed at three different locations within the magnetic field.

The computation predicted that the amount of average pollutants reduction is dependent on the location of the flames within the magnetic fields with respect to magnetic gradients. The mass weighted average of the soot volume fraction over the computational domain decreased when the non-premixed flame is located at certain locations within the magnetic field of the solenoid with respect to the absence of the magnetic fields, but increases in other locations.
A Digital Twin Environment Designed for the Implementation of Real Time Monitoring Tool
Authors: Pezzini Paolo , Bonilla Harry , Johnson Grant , Reinhart Zachary , Bryden Kenneth Mark
Published: August 2021

Real time models and digital twin environments represent a new frontier that allow the development of supplemental data analytics of measurable and unmeasurable parameters for a variety of power plant configurations. Performance prediction, monitoring of degradation effects, and a faster recognition of anomalous events during power plant load following operations and/or due to cyber-attacks can be easily detected with the support of digital twin environments. In the research work described in this article, a digital twin environment was developed to capture the dynamics of a micro compressor-turbine system modified for hybrid configuration at the Department of Energy’s National Energy Technology Laboratory (NETL). The innovative approach for the development of the digital twin environment was based on creating a compressor-turbine physics-based model using a stateless methodology generally utilized for microservices architectures. The advantage of using this approach was represented by modeling individual or a group of power plant components on distributed computational resources such as clouds in a lightweight and interchangeable manner.

Supplemental data analytics were performed using an online system identification tool developed in previous work and applied to an unmeasurable parameter only available in the digital twin system. This work demonstrated the ability to train a recursive algorithm to predict a supplemental parameter for faster anomaly detection or for replacing the physics-based model during design or monitoring of operational systems. The thermodynamic compressor-turbine net power was the unmeasurable parameter only available in the digital twin model, which was predicted with the online system identification tool. Results showed that the online system identification algorithm predicted the dynamic response of the thermodynamic net power based on a set of experimental data points at nominal operating conditions with an absolute mean percentage error of ∼0.644%.
Simulation Research on Explosives Detection System Based on D-D Sealed Neutron Generator
Authors: Gao Ya-Dong , He De-Dong , Gong Ke , Shi Guang-Yu , Chen Si-Yuan , Zhu Chen-Xi , Jing Shi-Wei
Published: August 2021

A prompt gamma neutron activation analysis (PGNAA) system based on a deuterium-deuterium (D-D) sealed neutron generator was designed using the MOCA code for explosive detection. The system is mainly composed of four parts: D-D sealed neutron generator, moderator, shielding, and Lutetium Yttrium OxyorthoSilicate (LYSO) scintillation detectors. Polyethylene (PE) was selected as the moderator and the optimal thickness was 7cm. Lead, PE, and boron-containing polyethylene were used as shielding materials. In the optimized model, the LYSO detector is used to measure eighteen materials, such as wood, melamine, glucose, and nylon, and so on. Firstly, the nitrogen characteristic peak of 10.8 MeV was analyzed to determine whether the material contained nitrogen. Then, the ratio of characteristic peak counts of C/O and O/N were calculated to distinguish explosives from nitrogen containing materials. Finally, dinitrobenzene, nitroglycerin, TNT, and ammonium nitrate can be separated from nitrogenous substances by a discriminant algorithm. The final device can be used to detect the chemical composition of the threat substances, and the maximum dose rate of the system meets the limits of international protection standards.
The Sandia National Laboratories Natural Circulation Cooler
Authors: Middleton Bobby D. , Brady Patrick V. , Lawles Serafina
Published: August 2021

Sandia National Laboratories (SNL) is developing a cooling technology concept — the Sandia National Laboratories Natural Circulation Cooler (SNLNCC) — that has potential to greatly improve the economic viability of hybrid cooling for power plants. The SNLNCC is a patented technology that holds promise for improved dry heat rejection capabilities when compared to currently available technologies. The cooler itself is a dry heat rejection device, but is conceptualized here as a heat exchanger used in conjunction with a wet cooling tower, creating a hybrid cooling system for a thermoelectric power plant.

The SNLNCC seeks to improve on currently available technologies by replacing the two-phase refrigerant currently used with either a supercritical fluid — such as supercritical CO2 (sCO2) — or a zeotropic mixture of refrigerants. In both cases, the heat being rejected by the water to the SNLNCC would be transferred over a range of temperatures, instead of at a single temperature as it is in a thermosyphon. This has the potential to improve the economics of dry heat rejection performance in three ways: decreasing the minimum temperature to which the water can be cooled, increasing the temperature to which air can be heated, and increasing the fraction of the year during which dry cooling is economically viable. This paper describes the experimental basis and the current state of the SNLNCC.
Stator Leakage Monitoring System in Water-Cooled Generators: Problems and Solutions
Authors: Bauer Thomas , Svoboda Matthias
Published: August 2021

An electrical generator is one of the most efficient large-scale machines. It converts mechanical to electrical energy with an efficiency coefficient of approximately 99%. The remaining 1% can mainly be contributed to heat losses. Direct cooling is only necessary for larger turbogenerators with more than 250 MVA where the cooling media is introduced via hollow conductors within the stator bars. Turbogenerators of approximately up to 700 MVA nowadays use exclusively hydrogen (H2) gas as a cooling media. Even larger turbogenerators have to introduce direct water cooling.

The water chemistry of the stator cooling water is typically of neutral pH and has a conductivity of less than 0.1 μS/cm. Two zones of the oxygen (O2) concentration have been established through the last 50 years, one at low dissolved O2 concentration with less than 20 ppb, the other with high concentrations of more than 2 ppm. The latter has to continuously inject CO2 free air to ensure to always keep the oxygen concentration above 2 ppm.

The first part of this publication shows several incidents with the air injection system in different Nuclear Power Plants in the US, resulting in unfavorable stator cooling water chemistry. This led to a reduced cooling efficiency, resulting in several chemical online cleanings being necessary.

The second part of this work presents a technical solution to overcome the issues associated with the reduced stator cooling. It continuously injects and monitors the air injected into the system. Additionally, it also measures the hydrogen leakage rate.
The Introduction and Analysis of the World’s First High-Temperature Retrofit Project on a Subcritical Coal-Fired Power Unit
Authors: Feng Weizhong , Li Li
Published: August 2021

Global warming concerns have pushed coal-fired power plants to develop innovative solutions which reduce CO2 emissions by increasing efficiency. While new ultra-supercritical units are built with extremely high efficiency, with Pingshan II approaching 50% LHV[1], subcritical units with much lower efficiency are a major source of installed capacity.

The typical annual average net efficiency of subcritical units in China is about 37% LHV, and some are lower than 35% LHV. Since the total subcritical capacity in China is about 350GW and accounts for over one third of its total coal-fired power capacity, shutting all subcritical units down is not practical.

Finding existing coal-fired plants a cost-effective solution which successfully combines advanced flexibility with high efficiency and low emissions, all while extending service lives, has challenged energy engineers worldwide. However, the (now proven) benefits a high temperature upgrade offers, compared to new construction options, made this an achievement worth pursuing.

After many years of substantial incremental improvements to best-in-class technology, this first-of-its-kind subcritical high temperature retrofit successfully proves that a technically and economically feasible solution exists. It increases the main and reheat steam temperatures from 538°C (1000°F) to 600°C (1112°F), and the plant cycle and turbine internal efficiencies are greatly improved.

This upgrade’s greatest efficiency gains occur at low loads, which is important as fossil plants respond to renewable energy’s increased grid contributions. These are combined with best-in-class flexibility, energy-savings, and technological advances, i.e., flue gas heat recovery technology and generalized regeneration technologies [4].

This project, the world’s first high-temperature subcritical coal-fired power plant retrofit, was initiated in April 2017 and finished in August 2019. Performance reports created by Siemens and GE record unit net efficiency at rated conditions improved from 38.6% to 43.5% LHV. The boiler’s lowest stable combustion load with operational SCR, without oil-firing support, was reduced from 55% to 19%. Substitution or upgrading of high-temperature components extended the lifetime of the unit by more than 30 years. At a third of the cost of new construction, this project set a high-water-mark for retrofitting subcritical units, and meets or supports the requisite attributes for Coal FIRST, Coal Plant of the Future, proposed by the United States Department of Energy (DOE) in 2019 [2].