bluuebunny/crossref_metadata_2025 huggingface dataset:
Illuminating the mysteries of wolf history
Authors: Schweizer Rena M. , Wayne Robert K.
Published: April 2020

One of the most enduring surprises about the genetic history of Late Pleistocene populations is that continuity is often disturbed by upheaval. In fact, studies that support population continuity are increasingly rare in humans, a variety of vertebrate taxa, and vascular plants (Hofreiter & Stewart 2009; Burbrink et al. 2016). Perhaps such continuity should not be expected as the Pleistocene is marked by episodes of climate change, glaciation and the invasions of humans into previously isolated areas. Although fossils are one of the primary sources for inferring population continuity, a problem with fossil material is that, even if similar morphological forms might exist in a place over time, they may not be from the same genetic lineage. There are now readily available methods to assess genetic continuity solely from DNA found in fossil material, provided the record is fairly continuous. In a From the Cover article in this issue of Molecular Ecology, Loog et al. (2020) apply some of these readily available methods to analyse mitochondrial genomes and model the demography of wolves over the last 50,000 years.
Community structure – Ecosystem function relationships in the Congo Basin methane cycle depend on the physiological scale of function
Authors: Meyer Kyle M. , Hopple Anya M. , Klein Ann M. , Morris Andrew H. , Bridgham Scott D. , Bohannan Brendan J. M.
Published: April 2020

Belowground ecosystem processes can be highly variable and difficult to predict using microbial community data. Here, we argue that this stems from at least three issues: (a) complex covariance structure of samples (with environmental conditions or spatial proximity) can make distinguishing biotic drivers a challenge; (b) communities can control ecosystem processes through multiple mechanisms, making the identification of these controls a challenge; and (c) ecosystem function assessments can be broad in physiological scale, encapsulating multiple processes with unique microbially mediated controls. We test these assertions using methane (CH4)‐cycling processes in soil samples collected along a wetland‐to‐upland habitat gradient in the Congo Basin. We perform our measurements of function under controlled laboratory conditions and statistically control for environmental covariates to aid in identifying biotic drivers. We divide measurements of microbial communities into four attributes (abundance, activity, composition, and diversity) that represent different forms of community control. Lastly, our process measurements differ in physiological scale, including broader processes (gross methanogenesis and methanotrophy) that involve more mediating groups, to finer processes (hydrogenotrophic methanogenesis and high‐affinity CH4 oxidation) with fewer mediating groups. We observed that finer scale processes can be more readily predicted from microbial community structure than broader scale processes. In addition, the nature of those relationships differed, with broad processes limited by abundance while fine‐scale processes were associated with diversity and composition. These findings demonstrate the importance of carefully defining the physiological scale of ecosystem function and performing community measurements that represent the range of possible controls on ecosystem processes.
Laudato Si's View on Integral Ecology in Light of the Planetary Boundaries Concept
Authors: De Tavernier Johan , Ndubueze Kingsley
Published: April 2020

Promoting ecological awareness and sustainability of God's creation is now considered as a primary task of the CST. However, from its beginning with Rerum Novarum, CST emphasizes the promotion of social justice and equity, and highlights the dangers of economic inequalities between richer and poorer nations and the need for distributive justice. To that effect, human development was its central theme, which is favored by the dominion mandate and is known nowadays as the Anthropocene. Important documents like Gaudium et Spes and Populorum Progressio are illustrative for this anthropocentric stance, while less attention is given to the wellbeing of nonhuman creatures and natural ecosystems. Nevertheless, from Octogesima Adveniens onwards, the CST starts to look into environmental issues. Pope Francis' Laudato Si' in 2015 introduces a significant shift by referring to nonhuman creatures as ‘our fellow creatures’, thereby extending ‘intrinsic value’ to all nonhuman creatures. In his integral ecology, he promotes a sustainable and integral development that favors the wellbeing of both human and natural environments. In this article, we assess Laudato Si's view on sustainability and integral development in confrontation with the wider framework of the Planetary Boundaries's concept of sustainable development.
Vasogenic edema in the medial temporal lobe during treatment of diabetic ketoacidosis in an elderly patient
Authors: Wakabayashi Hikaru , Kobayashi Zen , Kakei Takeshi , Ishihara Shoichiro , Tomimitsu Hiroyuki , Shintani Shuzo
Published: April 2020

A 68‐year‐old woman presented with a 1‐month history of appetite loss and weight loss, followed by vertigo and a decreased level of consciousness. A diagnosis of diabetic ketoacidosis (DKA) was made, and treatment of DKA was initiated. Her level of consciousness gradually improved, but time‐related disorientation as well as recent memory disturbance persisted even after a decrease in the level of blood glucose. Brain MRI demonstrated vasogenic edema in the left medial temporal lobe. Vasogenic cerebral edema during the treatment of DKA should be considered not only in children and young adults, but also in elderly patients.
The canalization hypothesis – challenges and alternatives
Authors: Ravichandran Sree Janani , Linh Nguyen Manh , Scarpella Enrico
Published: April 2020

The ‘canalization hypothesis’ was suggested 50 years ago by Tsvi Sachs to account for the formation of vascular strands in response to wounding or auxin application. The hypothesis proposes that positive feedback between auxin movement through a cell and the cell's auxin conductivity leads to the gradual selection of narrow ‘canals’ of polar auxin transport that will differentiate into vascular strands. Though the hypothesis has provided an invaluable conceptual framework to understand the patterned formation of vascular strands, evidence has been accumulating that seems to be incompatible with the hypothesis. We suggest that the challenging evidence is incompatible with current interpretations of the hypothesis but not with the concept at the core of the hypothesis' original formulation.
RLP/K enrichment sequencing; a novel method to identify receptor‐like protein (RLP) and receptor‐like kinase (RLK) genes
Authors: Lin Xiao , Armstrong Miles , Baker Katie , Wouters Doret , Visser Richard G. F. , Wolters Pieter J. , Hein Ingo , Vleeshouwers Vivianne G. A. A.
Published: April 2020

The identification of immune receptors in crop plants is time‐consuming but important for disease control. Previously, resistance gene enrichment sequencing (RenSeq) was developed to accelerate mapping of nucleotide‐binding domain and leucine‐rich repeat containing (NLR) genes. However, resistances mediated by pattern recognition receptors (PRRs) remain less utilized.

Here, our pipeline shows accelerated mapping of PRRs. Effectoromics leads to precise identification of plants with target PRRs, and subsequent RLP/K enrichment sequencing (RLP/KSeq) leads to detection of informative single nucleotide polymorphisms that are linked to the trait.

Using Phytophthora infestans as a model, we identified Solanum microdontum plants that recognize the apoplastic effectors INF1 or SCR74. RLP/KSeq in a segregating Solanum population confirmed the localization of the INF1 receptor on chromosome 12, and led to the rapid mapping of the response to SCR74 to chromosome 9. By using markers obtained from RLP/KSeq in conjunction with additional markers, we fine‐mapped the SCR74 receptor to a 43‐kbp G‐LecRK locus.

Our findings show that RLP/KSeq enables rapid mapping of PRRs and is especially beneficial for crop plants with large and complex genomes. This work will enable the elucidation and characterization of the nonNLR plant immune receptors and ultimately facilitate informed resistance breeding.
The influence of lateral flows in an aquifer on the agricultural value of groundwater
Authors: Kovacs Kent F. , Durand‐Morat Alvaro
Published: April 2020

Valuation of water in an aquifer depends on reliable information about the hydrologic conditions of an aquifer. Regions of depression emerge in an aquifer because groundwater cannot seamlessly flow between shallow and deep aquifer locations, and our analysis shows that the degree of lateral flow influences the value of the water in the aquifer. The assumption that groundwater declines uniformly over a landscape, a bathtub aquifer, leads to an underestimate of the value of a unit of water in an aquifer but an overestimate of the wealth that the aquifer represents. For the alluvial aquifer in Arkansas, USA, the average accounting price of water in an aquifer is almost 40% higher if there is no lateral flow, but the groundwater wealth is 10% lower. The value of an aquifer with the limited lateral flow is less sensitive to changes in agricultural markets, the discount rate, or the natural recharge of the aquifer.

Recommendations for Resource Managers

Average value of water in an aquifer with limited lateral flows is nearly 40% higher than the value of an aquifer with high lateral flows.

Groundwater wealth weights the accounting prices of water in the aquifer by the amount water underneath each site. As lateral flows decline, the wealth of the aquifer rises and then falls because the distribution of accounting prices change so most water is beneath sites with lower accounting prices.

The average value of water in an aquifer is less sensitive to changes in hydro‐economic model parameters such as the natural recharge or discount rate when the lateral flows are less.
Methylene blue and monosodium glutamate improve neurologic signs after fluoroacetate poisoning
Authors: DeLey Cox Vanessa E. , Hartog Matthew A. , Pueblo Erin , Racine Michelle , Jennings Laura , Tressler Justin , Tuet Wing Y. , Stone Samuel , Pierce Samuel A. , Thompson Lily , Dukes Aliyah , Hoard‐Fruchey Heidi , Wong Benjamin , McCranor Bryan J.
Published: April 2020

Fluoroacetate (FA) is a tasteless, odorless, water‐soluble metabolic poison with severe toxicological effects. Characterized in the mid‐1900s, it has been used as a rodenticide but is comparably lethal to all mammals. Many countries have restricted its use, and modern‐day accidental human exposures are rare, but recently, concerns have been raised about its application as a chemical weapon with no known antidote. A combined treatment of methylene blue (MB), an antioxidant, and monosodium glutamate (MSG), a precursor of the citric acid cycle substrate alpha‐ketoglutarate, has been recommended as an effective countermeasure; however, no peer‐reviewed articles documenting the efficacy of this therapy have been published. Using a rodent model, we assessed the effects of MB and MSG on the neurologic, cardiac, and pulmonary systems. Transcriptomic analysis was used to elucidate inflammatory pathway activation and guide bioassays, which revealed the advantages and disadvantages of these candidate countermeasures. Results show that MB and MSG can reduce neurologic signs observed in rats exposed to sodium FA and improve some effects of intoxication. However, while this strategy resolved some signs of intoxication, ultimately it was unable to significantly reduce lethality.
Characterization of ovarian development in girls from birth to 9 months
Authors: Chin Helen B. , Baird Donna D. , Kaplan Summer L. , Darge Kassa , Adgent Margaret A. , Ford Eileen G. , Rogan Walter J. , Stallings Virginia A. , Umbach David M.
Published: April 2020

Background

The minipuberty of infancy is a period of increased reproductive axis activity. Changes in reproductive hormone concentrations and organ size occur during this period, but longitudinal changes have not been well described.

Objectives

The objective of this study was to characterize ovarian growth trajectories and ovarian follicle development during the first 9 months of life in a large longitudinal cohort of healthy girls.

Methods

Data from the Infant Feeding and Early Development Study, a longitudinal cohort study of oestrogen‐responsive outcomes in healthy infants, were used to estimate ovarian growth trajectories and describe the presence of ovarian antral follicles in girls 0‐9 months old. Ovarian ultrasound evaluations were performed on the infants within 72 hours of birth (newborn visit) and at 4, 8, 16, 24, and 32 weeks of age. Mixed‐effects regression splines were used to characterize changes in ovarian volume during infancy and assess the association between the presence of ovarian follicles at the newborn visit and ovarian growth.

Results

This analysis included 163 girls with two or more ovarian ultrasounds in the study. Results from the estimated overall ovarian growth trajectory show that ovarian volume increases more than sixfold during the first 16 weeks after birth and then remains relatively stable in the later weeks of infancy. Among girls with observable ovaries at the newborn visit (n = 133), girls with at least one visible ovarian follicle showed more rapid initial ovarian growth compared with girls without visible follicles.

Conclusions

Infant ovarian volume increased to a peak at 16 weeks, which was influenced by the number and size of developing follicles. This research contributes to future development of reference ranges for postnatal ovarian growth in healthy, term infants.
Municipal Structure Matters: Evidence from Government Fiscal Performance
Authors: Wei Wenchi
Published: April 2020

Evidence for the fundamental presumption that municipal structure matters for government performance is smaller and weaker than many might expect. This research contributes evidence to the literature by focusing on how municipal structure affects government fiscal performance. Municipal structure is operationalized by constructing an index on a political‐administrative scale based on seven essential structural characteristics. As the index score increases, the municipal structure becomes less political and more administrative or professional. Theoretically, municipal structure can affect government performance by influencing managerial professionalism, managerial strategy stance, and the relative attention of government officials to managerial accountability and efficiency. The empirical evidence shows that municipalities adopting a structure with an imbalance toward administrative characteristics are more likely to achieve the best fiscal conditions in cash solvency, dependence on intergovernmental revenues, and outstanding debt level. Moreover, municipal structure moderates the influence of external environmental factors on government fiscal conditions.
MicroRNA regulation of Toll‐like receptor, RIG‐I‐like receptor and Nod‐like receptor pathways in teleost fish
Authors: Chu Qing , Xu Tianjun
Published: April 2020

The innate immune system is the first‐line defence against invading pathogens, and the main molecules involved in recognizing invading pathogens are the pattern recognition receptors. Accumulating evidences have demonstrated that activation and termination of the immune responses are regulated by various layers of regulators and mechanisms. MicroRNAs (miRNAs) are a group of small non‐coding RNAs that emerged as critical component of the complex regulatory networks in fish immune responses. In this review, we have summarized miRNA regulation in teleost fish, which can provide new insights into the regulation of innate immune receptor pathways in fish. Meanwhile, we comprehensively discuss the recent researches on how teleost miRNAs respond to the signalling pathways of innate immune receptors, including Toll‐like receptors, retinoic acid‐inducible gene‐I‐like receptors and Nod‐like receptors.
Fifty shades of binding: Appraising the enforcement toolkit for the EU’s 2030 renewable energy targets
Authors: Monti Alessandro , Martinez Romera Beatriz
Published: April 2020

In December 2018, the European Union (EU) adopted a recast of the Renewable Energy Directive (RED II), which introduces a new target of 32 percent renewable energy to be reached at the EU level by 2030. This target represents a discontinuity with the one enshrined in the previous Directive (RED I), as it is binding only for the EU as a whole but not for individual Member States. Such a policy shift paves the way to new legal challenges for the deployment of renewable energy. Yet, the contextual approval of the Regulation on the Governance of the Energy Union also provides the European Commission with an enforcement toolkit to respond to Member States’ ambition and delivery gaps in their National Energy and Climate Plans. Providing an appraisal of the RED II and the Governance Regulation, this article argues that, despite the lack of binding renewable energy targets at Member State level, the Commission is equipped with the necessary instruments to ensure the enforcement of the collective 2030 renewable energy target.
Facilitators and barriers associated with the implementation of a Swedish psychosocial dementia care programme in Japan: a secondary analysis of qualitative and quantitative data
Authors: Nakanishi Miharu , Ziylan Canan , Bakker Ton , Granvik Eva , Nägga Katarina , Nishida Atsushi
Published: April 2020

Background

A psychosocial dementia care programme for challenging behaviour (DEMBASE®) was developed in collaboration with a Swedish BPSD‐registry team for in‐home care services use in Japan. The programme consisted of a web‐based tool for the continued assessment of challenging behaviours and interdisciplinary discussion meetings. Effectiveness of the adapted programme was verified through a cluster‐randomised controlled trial. The Tokyo Metropolitan Government provided municipal funding to introduce the programme into daily practice beginning in April 2018.

Objectives

To investigate both facilitators and barriers associated with programme implementation.

Design

A secondary analysis of qualitative and quantitative data.

Settings

Data were collected in naturalistic long‐term care settings from April 2018 to March 2019.

Participants

A total of 138 professionals and 157 people with dementia participated in the programme.

Methods

Challenging behaviour in persons with dementia was assessed by professionals using a total Neuropsychiatric Inventory score. Data on expected facilitators and barriers were extracted for qualitative analysis from a debriefing meeting between professionals.

Results

Of the 157 persons with dementia, 81 (51.6%) received follow‐up behavioural evaluations by March 2019. The average level of challenging behaviour was significantly reduced for 81 persons from baseline to their most recent follow‐up evaluations. Facilitators included ‘programme available for care managers’, ‘visualised feedback on professionals’ work’, ‘affordable for providers and professionals’ and ‘media coverage’. Barriers included ‘professionals from different organisations’, ‘unpaid work’, ‘operation requirement for municipalities’ and ‘conflict with daily benefit‐oriented framework’.

Conclusions

A follow‐up evaluation was not fully achieved. Further strategies to address barriers may include the development of a benefit‐rewarding scheme for interdisciplinary discussion meetings, an e‐learning system capable of substituting training course portions and a cross‐municipality training course.
Psychometric evaluation of the Swedish Quality of Dyadic Relationships scale – homogeneity and construct validity
Authors: Gudjonsdottir Johanna , Eklund Mona , Ingberg Edvin , Ström Jakob O.
Published: April 2020

Rationale and aims

The Quality of Dyadic Relationships is a self‐assessment scale used to evaluate various aspects of relationship quality. Psychometric evaluation by the developers of the instrument has led to a nontested amended version. Further psychometric testing is thus warranted, and the aim of this study was to evaluate homogeneity, construct validity (in terms of concurrent, discriminant and known‐groups validity) and any floor and ceiling effects of the Quality of Dyadic Relationships.

Methods

Forty‐seven cohabitant couples (47 women with a mean age of 30.0 years and 47 men with a mean age of 31.5 years) answered the Quality of Dyadic Relationships, the Relationship Assessment Scale (to test concurrent validity) and the Perceived Stress Scale (to test discriminant validity). Homogeneity (internal consistency) was calculated by Cronbach’s alpha. Concurrent and discriminant validity were estimated as correlations between Quality of Dyadic Relationships and the other instruments. Assessment of known‐groups validity was based on the variables of parental status and gender. Floor and ceiling effects were evaluated according to frequency distribution.

Results

The overall homogeneity was good with acceptable Cronbach’s alpha values (α > 0.70) for all subscales but dyadic sexuality. Concurrent validity and discriminant validity were found. Known‐groups validity was indicated by significant differences between individuals with different parental status on the total QDR index, where the ones without children scored higher. No difference between the genders was found. No significant floor effects were found, but a significant ceiling effect was found in the subscale dyadic sensuality, with 27.7% of respondents scoring maximum.

Conclusion

In all, the QDR showed promising psychometric properties and may be used for screening and follow‐up purposes. However, it can benefit from further development, as suggested by the ceiling effect in the subscale dyadic sensuality and the low internal consistency in the subscale dyadic sexuality.
Uncertainties in BP management in dialysis patients
Authors: Doulton Timothy W. R. , Swift Pauline A. , Murtaza Asam , Dasgupta Indranil
Published: April 2020

Hypertension in dialysis patients is extremely common. In this article, we review the current evidence for blood pressure (BP) goals in hemodialysis patients, and consider the effectiveness of interventions by which BP may be lowered, including manipulation of dietary and dialysate sodium; optimization of extracellular water; prolongation of dialysis time; and antihypertensive medication. Although two meta‐analyses suggest lowering BP using antihypertensive drugs might be beneficial in reducing cardiovascular events and mortality, there are insufficient rigorously designed trials in hypertensive hemodialysis populations to determine preferred antihypertensive drug classes. We suggest aiming for predialysis systolic BP between 130 and 159 mm Hg, while at the same time acknowledge the significant limitations of the data upon which it is based. We conclude by summarizing current knowledge as regards management of hypertension in the peritoneal dialysis population and make recommendations for future research in this field.
The effect of biological maturity status on ground reaction force production during sprinting
Authors: Colyer Steffi L. , Nagahara Ryu , Takai Yohei , Salo Aki I.T.
Published: April 2020

Sprint ability develops nonlinearly across childhood and adolescence. However, the underpinning ground reaction force (GRF) production is not fully understood. This study aimed to uncover the kinetic factors that explain these maturation‐related sprint performance differences in Japanese boys and girls. A total of 153 untrained schoolchildren (80 boys, 73 girls) performed two 50‐m maximal effort sprints over a 52‐force‐platform system embedded in an indoor track. Maturity offset (years from peak height velocity; PHV) was estimated using anthropometric data and used to categorise the children into six‐year‐long maturation groups (from group 1 [5.5‐4.5 years before PHV] to group 6 [0.5 years before to 0.5 years after PHV). Maximum and mean step‐averaged velocities across 26 steps were compared across consecutive maturation groups, with further GRF analysis (means and waveforms [statistical parametric mapping]) performed when velocity differences were observed. For boys, higher maximum velocities (effect size ± 90% CI = 1.63 ± 0.69) were observed in maturation group 2 (4.5‐3.5 years before PHV) compared to group 1 (5.5‐4.5 years before PHV), primarily attributable to higher antero‐posterior GRFs across shorter ground contacts. Maximum velocities increased from maturation group 4 (2.5‐1.5 years before PHV) to group 5 (1.5‐0.5 years before PHV) in the girls (effect size ± 90% CI = 1.00 ± 0.78), due to longer ground contacts rather than higher GRFs per se. Waveform analyses revealed more effective reversal of braking forces and higher propulsive forces (e.g. 14%‐77% of stance 4), particularly for comparisons involving boys, which suggested potentially enhanced stretch‐shortening ability. Youth sport practitioners should consider these maturation‐specific alterations when evaluating young athletes’ sprint abilities.
Solution of Biharmonic Equation in Complicated Geometries With Physics Informed Extreme Learning Machine
Authors: Dwivedi Vikas , Srinivasan Balaji
Published: April 2020

Recently, physics informed neural networks (PINNs) have produced excellent results in solving a series of linear and nonlinear partial differential equations (PDEs) without using any prior data. However, due to slow training speed, PINNs are not directly competitive with existing numerical methods. To overcome this issue, the authors developed Physics Informed Extreme Learning Machine (PIELM), a rapid version of PINN, and tested it on a range of linear PDEs of first and second order. In this paper, we evaluate the effectiveness of PIELM on higher-order PDEs with practical engineering applications. Specifically, we demonstrate the efficacy of PIELM to the biharmonic equation. Biharmonic equations have numerous applications in solid and fluid mechanics, but they are hard to solve due to the presence of fourth-order derivative terms, especially in complicated geometries. Our numerical experiments show that PIELM is much faster than the original PINN on both regular and irregular domains. On irregular domains, it also offers an excellent alternative to traditional methods due to its meshless nature.
Modeling of Flexible Beam Networks and Morphing Structures by Geometrically Exact Discrete Beams
Authors: Lestringant Claire , Kochmann Dennis M.
Published: April 2020

We demonstrate how a geometrically exact formulation of discrete slender beams can be generalized for the efficient simulation of complex networks of flexible beams by introducing rigid connections through special junction elements. The numerical framework, which is based on discrete differential geometry of framed curves in a time-discrete setting for time- and history-dependent constitutive models, is applicable to elastic and inelastic beams undergoing large rotations with and without natural curvature and actuation. Especially, the latter two aspects make our approach a versatile and efficient alternative to higher-dimensional finite element techniques frequently used, e.g., for the simulation of active, shape-morphing, and reconfigurable structures, as demonstrated by a suite of examples.
Effect of Homogenization on the Microstructure and Magnetic Properties of Direct Laser-Deposited Magnetocaloric Ni43Co7Mn39Sn11
Authors: Stevens Erica , Kimes Katerina , Chernenko Volodymyr , Lázpita Patricia , Wojcik Anna , Maziarz Wojciech , Toman Jakub , Chmielus Markus
Published: April 2020

Transitioning current cooling and refrigeration technologies to solid-state cooling leveraging the magnetocaloric effect would improve efficiency and eliminate a harmful influence on the environment. Employing additive manufacturing as a production method would increase geometrical freedom and allow designed channels and porosity in heat exchangers made from magnetocaloric materials, to increase surface area for heat transfer via a fluid. This study is the first to demonstrate a successful deposition of the Ni43Co7Mn39Sn11 magnetocaloric material by direct laser deposition. Samples were defined as either properly- or overbuilt, and representative ones were characterized for microstructural features before and after homogenization heat treatment, as well as magnetic behavior and constituent phases. As-built microstructures consisted of dendrites, columnar grains, and elongated cells, with a mix of both austenite and 7M martensite phases. Homogenization increased the fraction of 7M martensite, and encouraged distinct equiaxed and columnar grains, eliminating dendrites and cellular structures. The increased fraction of the weak magnetic martensitic phase also resulted in a strong reduction of the saturation magnetization. Some differences in structure and performance may be related to an energy density difference causing higher Mn loss in the properly built sample, with a lower powder-to-energy input ratio. As a whole, it is found that direct laser deposition (DLD) additive manufacturing of Ni-Mn-based magnetocaloric material is very promising, since representative transformation, phase state, and magnetic properties have been achieved in this study.
Surface Modification of Additively Manufactured 18% Nickel Maraging Steel by Ultrasonic Vibration-Assisted Ball Burnishing
Authors: Ituarte Iñigo Flores , Salmi Mika , Papula Suvi , Huuki Juha , Hemming Björn , Coatanea Eric , Nurmi Seppo , Virkkunen Iikka
Published: April 2020

The scope of this research is to characterize and optimize the vibration-assisted ball burnishing of additively manufactured 18% Nickel Maraging steel for tooling applications. We evaluate the suitability of vibration-assisted ball burnishing as an alternative method to post-process additively manufactured tool steel. To do so, we assessed a single pass post-processing technique to enhance surface roughness, surface micro-hardness, and residual stress state. Results show that ultrasonic burnishing after age hardening functionalizes additively manufactured surfaces for tooling applications creating a beneficial compressive residual stress state on the surface. The surface micro-hardness (HV1) varied between 503 and 630 HV1, and the average surface roughness (Ra) varied between 1.31 and 0.14 µm, depending on process parameters with a maximum productivity rate of 41.66 cm2/min making it an alternative approach to functionalize additively manufactured tool components.
Numerical Optimization of an Ejector for Waste Heat Recovery Used to Cool Down the Intake Air in an Internal Combustion Engine
Authors: Galindo José , Gil Antonio , Dolz Vicente , Ponce-Mora Alberto
Published: April 2020

In the present paper, a numerical investigation of a jet-ejector is carried out using a real gas model of R1234yf. The prototype under investigation works with specific operating conditions of a jet-ejector refrigeration system intended for waste heat recovery in an internal combustion engine (ICE). In the first instance, the geometry optimization involving nozzle exit diameter, mixing chamber diameter, and nozzle exit position (NXP) is performed. Once the optimum geometry has been obtained, the jet-ejector prototype is tested with different operating pressure ratios to determine its off-design performance. The flow structure in relevant cases has been examined with an emphasis on critical and subcritical modes. The flow phenomena occurring during expansion, entrainment, and mixing processes are discussed so performance degradation can be directly related to physical processes. The analysis has been completed fitting simulated points to critical and subcritical planar surfaces. The results in terms of goodness of fit are satisfactory so the jet-ejector performance in off-design operating conditions can be reflected through simple mathematic models. When the overall cycle is assessed by using previous computational fluid dynamics (CFD) maps, it is observed that the achievable cooling drops significantly when an ambient temperature of 31 °C is exceeded.
Unsteady Heat Transfer Between Gas and Tube in a Wave Rotor Refrigerator
Authors: Hu Dapeng , Wang Jingxian , Wu Mei , Liu Tingjiang , Zhao Yiming , Yu Yang
Published: April 2020

The performance of a wave rotor refrigerator (WRR) is strongly affected by unsteady heat transfer between gas and tubes. In this work, the mechanism of the heat transfer and its effects on WRR were investigated numerically and experimentally. Results show that the heat absorption of wave rotor occurs in the process of shock wave propagation, and heat release happens in other processes. The unsteady heat transfer causes an uneven wall temperature. The temperature varies along the longitudinal direction, while the time variation can be neglected. Furthermore, the position of the bolts, which link the wave rotor and the shaft, has a great influence on WRR gaps. The closer the position of bolts to the high-pressure (HP) nozzle is, the less effect of gaps would be. The research is an important guiding significance to the improvement of WRR refrigeration performance and WRR design.
Steam Condensation Heat Transfer During Initial Blow-Down Period of a Severe Nuclear Accident
Authors: Yadav Mahesh Kumar , Punetha Maneesh , Bhanawat Abhinav , Khandekar Sameer , Sharma Pavan K.
Published: April 2020

Heat transfer coefficient (HTC) relations developed using steady-state experimental data are used for capturing the complete heat transport characteristic in a severe nuclear accident. It is important to verify the applicability of these correlation(s) at an early stage of the accident where heat transfer is transient in nature. In this paper, an experimental study is executed for this purpose. High-pressure steam (at 0.26 MPa (2.6 bar) and 0.41 MPa (4.1 bar) absolute pressure) is leaked into the closed containment initially filled with atmospheric air, and filmwise condensation is studied on an isothermally maintained vertical stainless steel test plate. During the experiment, temperature variation across the test plate at specified locations and inside the containment are recorded using the microthermocouples. The steam–air mixture composition is also examined using an online mass-spectrometry system. An inverse heat conduction (IHC) technique, validated using air-jet impingement heat transfer data, is used to estimate the time-varying condensation heat flux. It is found that the existing correlations based on the steady-state experimental data predict the transient condensation flux quite well, except in very early transient situation with a time scale of ∼20 s.
Energy distribution in Dual-UAV collaborative transportation through load sharing
Authors: Mohiuddin Abdullah , Zweiri Yahya , Almadhoun Randa , Taha Tarek , Gan Dongming
Published: April 2020

In this paper, a novel dual-UAV collaborative aerial transport strategy based on energy distribution and load sharing is proposed. This paper presents the first experimental demonstration of dual-UAV collaborative aerial transport while distributing power consumption. The demonstration is performed while distributing the power consumption between two drones sharing a load based on their battery state of charge. A numerical model of the dual-hex-rotor-payload is used to validate the proposed strategy. Numerical and hardware tests were conducted to demonstrate the load distribution using multiple UAV with certain spatial configurations. Finally, collaborative aerial transport test scenarios are performed numerically and experimentally. The simulation and experimental results show the effectiveness and applicability of the proposed strategy.
Dead Center Identification of Two-Degrees-of-Freedom Planar Parallel Manipulator Using Graph Theory and Transmission Angle
Authors: Nie Liangyi , Ding Huafeng
Published: April 2020

Parallel manipulators are widely applied for their advantages of high stiffness, load-bearing, operation speed, and precision positioning capabilities, which are required in many industrial applications. However, dead center identification is a challenging task and fundamental problem during design stage of parallel manipulators, and becomes more intractable for two-degrees-of-freedom (DOF) complex planar parallel manipulators (PPMs) design. This paper proposes a method to identify the dead center positions of two-DOF PPMs based on graph theory and transmission angle. First, these PPMs are denoted by a set of independent loops using a topological structural analysis of the kinematic chains and structural decomposition. Then, the relationship between the mobility factor and the loop factor in the same independent loop is utilized to obtain the folded or stretched operation to form the new PPMs containing the corresponding instantaneous virtual loop. Subsequently, the dead center positions can be located since the corresponding transmission angle of the new PPMs is equal to 0 deg or 180 deg. As a result, the solved dead center positions of the two-DOF three types seven-bar, nine-bar, and 11-bar PPMs will provide guidance for the proper design of these PPMs. Finally, the Jacobian method for identifying the dead center position is then used to verify the proposed method. The proposed method is systematic and programmable and can be applied to any two-DOF PPM regardless of the number of independent loops or types of joints.
Multi-Objective Redundancy Allocation for Multi-State System Design Under Epistemic Uncertainty of Component States
Authors: Xiahou Tangfan , Liu Yu , Zhang Qin
Published: April 2020

Multi-state is a typical characteristic of engineered systems. Most existing studies of redundancy allocation problems (RAPs) for multi-state system (MSS) design assume that the state probabilities of redundant components are precisely known. However, due to lack of knowledge and/or ambiguous judgements from engineers/experts, the epistemic uncertainty associated with component states cannot be completely avoided and it is befitting to be represented as belief quantities. In this paper, a multi-objective RAP is developed for MSS design under the belief function theory. To address the epistemic uncertainty propagation from components to system reliability evaluation, an evidential network (EN) model is introduced to evaluate the reliability bounds of an MSS. The resulting multi-objective design optimization problem is resolved via a modified non-dominated sorting genetic algorithm II (NSGA-II), in which a set of new Pareto dominance criteria is put forth to compare any pair of feasible solutions under the belief function theory. A numerical case along with a SCADA system design is exemplified to demonstrate the efficiency of the EN model and the modified NSGA-II. As observed in our study, the EN model can properly handle the uncertainty propagation and achieve narrower reliability bounds than that of the existing methods. More importantly, the original nested design optimization formulation can be simplified into a one-stage optimization model by the proposed method.
Study on Building Digital-Twin of Face-Milled Hypoid Gear From Measured Tooth Surface Topographical Data
Authors: Lee Yi-Hui , Fong Zhang-Hua
Published: April 2020

A highly accurate digital-twin spiral bevel gear or hypoid gear is often required for dynamic analysis or stress analysis for gear transmission. However, a highly accurate digital-twin solid model is not always available because the final hypoid gear is completed by the gear manufacturer. This study constructs a digital-twin from a sample hypoid gear. The tooth surface of sample gear is digitized as topographical grids using a coordinate measuring machine (CMM) or a gear measurement center. The geometric parameters (the surface position vector, the normal vector, the principal curvatures, and the corresponding principal directions) for the measured tooth surface (MTS) are then extracted using numerical differential geometry (NDG). The machine settings and the cutter parameters for the sample hypoid gear are obtained by minimizing the topographical error between the replicated digital-twin and the sample gear using optimization software. The initial estimation for the machine settings and the cutter parameters is calculated using an explicit form of the modified-roll motion (MRM), which decreases numerical divergence and time that is required for calculation. The machine settings, the cutting tool parameters, and the auxiliary flank modification (AFM) motion are used as the design variables. A numerical example is presented to verify the proposed methodology. The numerical results show that the replicated digital-twin that is developed using the proposed method is sufficiently accurate for industrial applications.
Investigation of a Voronoi Diagram Representation for the Computational Design of Additively Manufactured Discrete Lattice Structures
Authors: Stanković Tino , Shea Kristina
Published: April 2020

A lattice structure is defined by a network of interconnected structural members whose architecture exhibits some degree of regularity. Although the overall architecture of a lattice may contain many members, its generation can be a simple process in which a unit cell composed of a small amount of members, in comparison to the overall structure, is mapped throughout the Euclidean space. However, finding the right lattice architecture in a vast search space that customizes the behavior of a design for a given purpose, subject to mechanical and manufacturing constraints, is a challenging task. In response to this challenge, this work investigates a Voronoi diagram-based tessellation of a body-centered cubic cell for applications in structural synthesis and computational design of 3D lattice structures. This work contributes by exploring how the Voronoi tessellation can be utilized to parametrically represent the architecture of a lattice structure and what the implications of the parametrization are on the optimization, for which a global direct search method is used. The work considers two benchmark studies, a cubic and a cantilever lattice structure, as well as the effect of isotropic and anisotropic material property models, stemming from applications to additive manufacturing. The results show that the proposed parameterization generates complex search spaces using only four variables and includes four different lattice structure types, a Kelvin cell, a hexagonal lattice, a diamond-core lattice structure, and a box-boom type lattice structure. The global direct search method applied is shown to be effective considering two different material property models from an additive manufacturing (AM) process.
Computational Study on Machine Settings for Face-Milled Hypoid Gears With Low Shaft Angles
Authors: Yang Xingyu , Song Chaosheng , Zhu Caichao , Liu Siyuan , Liang Chengcheng
Published: April 2020

Hypoid gear with small cone angle and large pitch cone distance can be directed at the transmission with low shaft angle (LSA). The manufacturing process has more freedoms of motion to control the tooth surface and ensure higher mesh performance. However, it is difficult to adjust the machine settings due to the extreme geometry. This paper focused on the manufacturing process and machine settings calculation of hypoid gear with low shaft angle (LSA hypoid gear). Based on the generating process, nongenerated gear, and generated pinion manufactured by circular cutter blade, the mathematic model of tooth surface of LSA hypoid gear was developed, and the expressions of principal directions and curvatures of LSA hypoid gear were derived. The relationship of curvatures between pinion and gear was also proposed. Then based on the basic relationships of two mating surfaces, an approach to determinate machine settings for LSA hypoid gear was proposed. Finally, the tooth contact analysis (TCA) and loaded tooth contact analysis (LTCA) were directed at the validation of machine settings’ derivation. TCA contact pattern results highly coincide with the preset values. And the LTCA contact pattern also highly coincides with TCA results, it can be considered that the determination approach of machine settings is valid. The TCA transmission error result also shows that the ratio of contact is quite large, which is a little bigger than 2. Thus, the load bearing ability and stability of LSA hypoid gear may be superior.
The role of grey-scale ultrasound in the diagnosis of adhesive capsulitis of the shoulder: a systematic review and meta-analysis
Authors: Wu Huaiyu , Tian Hongtian , Dong Fajin , Liang Weiyu , Song Di , Zeng Jieying , Ding Zhimin , Shi Yang , Luo Hui , Xu Jinfeng
Published: April 2020

Aims: In this systematic review and meta-analysis, we discuss the value of grey-scale ultrasonography (US) in diagnosing adhesive capsulitis of the shoulder (ACS).Material and methods: We retrieved relevant studies from PubMed, Cochrane Library, and Embase before 8 April 2019. We selected 7 studies concerning 446 patients (490 shoulders) that used grey-scale US to diagnose ACS and magnetic resonance imaging (MRI) or arthroscopy as the reference standard. We assessed the diagnostic accuracy of US on the basis of combined sensitivity, specificity, likelihood ratio (LR), and the area under the summary receiver operating characteristic (SROC) curve (AUC).Results: The combined sensitivity, specificity, positive LR and negative LR were found to be 88% (95%CI: 74–95), 96% (95%CI: 88–99), 23.89 (95%CI: 6.31–90.51) and 0.12 (95%CI: 0.05–0.29), respectively. The AUC was 0.97 (95%CI: 0.96–0.98). ACS was diagnosed on the basis of four US features: coracohumeral ligament thickening, inferior capsule/axillary recess capsule thickening, rotator interval abnormality, and restriction of the range of motion. The corresponding sensitivities were 64.4 (95%CI: 48.8–78.1), 82.1 (95%CI: 73.8–88.7), 82.6 (95%CI: 74.1–89.2) and 94.3 (95%CI: 84.3–98.8), respectively, and specificities were 88.9 (95%CI: 76.0–96.3), 95.7 (95%CI: 90.3–98.6), 93.9 (95%CI: 89.8–96.7), and 90.9 (95%CI: 75.7–98.1), respectively.Conclusions: Our meta-analysis showed that grey-scale US plays a significant role in the diagnosis of ACS. Because of its high sensitivity and specificity, US can be added to the existing clinical diagnosis program.
Gold photoemission survey spectra from hard x rays
Authors: Flanagan Timothy M. , Brumbach Michael T. , Chow Rebecca , Casalnuovo Dominic , Rubio-Zuazo Juan , Castro Germán R.
Published: April 2020

Polished single crystal gold was analyzed using hard x-ray photoemission at six different x-ray energies, nominally 8.0, 11, 13, 15, 18, and 22 keV. Survey spectra were recorded with each excitation to a maximum kinetic energy of 15 keV.
Investigations of the high-frequency dynamic properties of polymeric systems with quartz crystal resonators
Authors: Shull Kenneth R. , Taghon Meredith , Wang Qifeng
Published: April 2020

Opportunities arising from the use of the rheometric quartz crystal microbalance (RheoQCM) as a fixed frequency rheometer operating at 15 MHz are discussed. The technique requires the use of films in a specified thickness range that depends on the mechanical properties of the material of interest. A regime map quantifying the appropriate thicknesses is developed, based on the properties of a highly crosslinked epoxy sample that is representative of a broad class of polymeric materials. Relative errors in the measured film properties are typically in the range of several percent or less and are minimized by using a power law model to relate the rheological properties at two different resonant harmonics of the quartz crystal. Application of the RheoQCM technique is illustrated by measuring the temperature- and molecular weight-dependent properties of polystyrene and poly(methyl methacrylate) in the vicinity of the glass transition.