bluuebunny/crossref_metadata_2025 huggingface dataset:
A preliminary investigation of sleep quality and patient‐reported outcomes in pediatric solid organ transplant candidates
Authors: Gutierrez‐Colina Ana M. , Cushman Grace K. , Eaton Cyd K. , Quast Lauren F. , Lee Jennifer , Rich Kristin Loiselle , Reed‐Knight Bonney , Mee Laura , Romero Rene , Mao Chad Y. , George Roshan , Blount Ronald L.
Published: January 2019

The current cross‐sectional, single‐center study aimed to examine sleep quality in a sample of adolescents awaiting solid organ transplantation and to explore associations between sleep quality and both health‐related quality of life and barriers to adherence. Thirty adolescents between the ages of 12 and 18 years (M age = 15.26, SD = 1.89) who were awaiting transplantation participated in this study. Participants completed measures of sleep quality, health‐related quality of life, and barriers to adherence. T test and correlational analyses were performed to examine study aims. Adolescents awaiting transplantation had significantly lower levels of overall sleep quality compared to published norms of healthy peers. Domains of sleep quality were positively related to emotional and psychosocial health‐related quality of life. Sleep quality domains were also negatively related to adherence barriers. This study provides preliminary evidence demonstrating that sleep quality among transplant candidates is compromised, and that poor sleep quality is related to adolescents’ functioning across a number of domains during the pretransplant period. Results highlight the clinical importance of assessing and targeting sleep functioning in adolescents awaiting transplantation in order to reduce the negative influence of suboptimal sleep on functioning during this vulnerable period.
Evidence: A Guide for the Uncertain
Authors: Dorst Kevin
Published: January 2019

Assume that it is yourevidencethat determines what opinions you should have. I argue that since you should take peer disagreement seriously, evidence must have two features. (1) It must sometimes warrant beingmodest: uncertain what your evidence warrants, and (thus) uncertain whether you’re rational. (2) But it must always warrant beingguided: disposed to treat your evidence as a guide. It is surprisingly difficult to vindicate these dual constraints. But diagnosing why this is so leads to a proposal—Trust—that is weak enough to allow modesty but strong enough to yield many guiding features. In fact, I argue that Trust is theGoldilocks principle—for it is necessary and sufficient to vindicate the claim that you should always prefer to use free evidence. Upshot: Trust lays the foundations for a theory of disagreement and, more generally, an epistemology that permits self‐doubt—a modest epistemology.
Measuring Complex State Policies: Pitfalls and Considerations, with an Application to Race and Welfare Policy
Authors: Plutzer Eric , Berkman Michael B. , Honaker James , Ojeda Christopher , Whitesell Anne
Published: January 2019

Welfare policy is multidimensional because of the political compromises, competing goals, and federalist structure underpinning it. This complexity has hindered measurement and, therefore, the comparability of research on race and welfare policy. This paper describes a measurement strategy that is transparent, replicable, and attuned to matching the assumptions of statistical models to the policy process. We demonstrate that this strategy leads to more nuanced conclusions regarding the relationship between minority caseloads and the flexibility of state welfare policies. The strategy and recommendations are adaptable to research agendas that scholars bring to the comparative study of welfare in the U.S. states, countries, or other units—and to other complex policies enacted in federal systems.
Next of kin's perceptions of the meaning of participation in the care of older persons in nursing homes: a phenomenographic study
Authors: Ekström Kajsa , Spelmans Sanna , Ahlström Gerd , Nilsen Per , Alftberg Åsa , Wallerstedt Birgitta , Behm Lina
Published: January 2019

Background

Being involved in the care of a loved one is a desire of many next of kin. However, according to several studies of the perceptions of nursing home staff, the involvement of next of kin is not an obvious part of care. To be able to involve next of kin in care at nursing homes, the perceptions of what participation means are an important piece of knowledge. The aim of this study was therefore to describe variations in next of kin's perceptions of the meaning of participation in the care of older persons living in nursing homes.

Methods

Eighteen next of kin of older persons living in ten nursing homes in Sweden were recruited for interviews. The study design was based on a phenomenographic approach, focusing on the qualitatively different ways in which a person perceives, experiences or conceptualises a phenomenon or certain aspect of reality.

Results

Five categories emerged from analysis of the interviews, representing the next of kin's perceptions of the meaning of participation in the care of older persons in nursing homes: be present; communicate; monitor; do practical tasks; and to represent. The next of kin expressed meanings that belonged to more than one category, and the categories were interdependent.

Conclusions

Our results indicate that there are several meanings of next of kin's perceptions of participation at nursing homes. Nursing home staff's knowledge of these perceptions is important to enable next of kin to participate according to their own preferences.
Gradient‐based 3D skin roughness rendering from an in‐vivo skin image for dynamic haptic palpation
Authors: Vicente Julia I. , Kim Kwangtaek
Published: January 2019

Background/Purpose

Many studies have revealed the importance of palpation for dermatologists; however, palpation is not always possible due to the risk of secondary infections or the risk of damaging the affected area. Thus, haptic rendering for indirect palpation using in‐vivo skin images, which will enable to examine a real three‐dimensional (3D) skin sample by virtual touch without directly palpating the infected skin area, could be a useful technology in dermatology.

Methods

We propose a new method of accurate 3D skin surface reconstruction using simple gradients from a single skin image for accurate 3D roughness rendering with a haptic device. Our approach takes advantage of bilateral filtering to preserve skin roughness and image gradients in order to generate a 3D skin surface (polygonal meshes) while preserving skin wrinkles and rough surface textures.

Results

Our method was evaluated using two experiments. The accuracy was tested with six 3D ground‐truth surfaces and four clinical skin images (acne, miliaria, sweet syndrome, and herpes simplex). For objective evaluation, a well‐known 3D roughness estimation method and the Hausdorff distance were adopted to compute errors. All results showed that the accuracy of our method is superior to that of the two existing methods.

Conclusion

Haptic roughness rendering for skin palpation examination requires efficient and accurate 3D surface reconstruction. In this study, we developed a new method that can be used to reconstruct a 3D skin surface accurately while preserving roughness through the use of a single skin image.
Non‐invasive analysis of skin mechanical properties in patients with lamellar ichthyosis
Authors: Cortés Hernán , Magaña Jonathan J. , Reyes‐Hernández Octavio D. , Zacaula‐Juárez Noé , González‐Torres Maykel , Diaz‐Beltrán Wendy , León‐Trejo María C. , Cariño‐Calvo Lizbeth , Leyva‐Gómez Gerardo , González‐Del Carmen Manuel
Published: January 2019

Background

Reliable methods for the quantitative evaluation of skin of patients with ichthyosis are critically needed. Our purpose was to evaluate the biomechanical parameters of skin in a cohort of patients with clinically diagnosed lamellar ichthyosis.

Materials and methods

Twenty‐two patients diagnosed with lamellar ichthyosis were studied. Ichthyosis plaques located in upper distal limbs were assayed, and a nearby anatomical region without plaques from the same patient was employed as control. Skin biomechanical properties were studied through a non‐invasive device (Cutometer® MPA 580).

Results

Ichthyosis plaques had higher values for the Uf‐Ua parameter and lower values for the Ua/Uf, Ur/Ue, and Ur/Uf parameters. Adults and children showed similar statistical differences. There were no significant differences in data from men, whereas in women differences for all of the parameters were found. There was a significant decrease in the hydration and an increase in melanin index in the ichthyosis plaques.

Conclusion

Our results suggest that analysis of parameters Uf‐Ua, Ua/Uf, Ur/Ue, Ur/Uf, hydration, and melanin index could be employed for quantitative monitoring of skin. Therefore, the non‐invasive method applied may be suitable for evaluation of skin of patients with ichthyosis in response to medical treatments.
Tattoos and skin barrier function: Measurements of TEWL, stratum corneum conductance and capacitance, pH, and filaggrin
Authors: Nørreslet Line Brok , Serup Jørgen , Kezic Sanja , Engebretsen Kristiane Aasen , Thyssen Jacob P. , Agner Tove , Clausen Maja‐Lisa
Published: January 2019

Background

Initially after tattooing, the skin barrier function is broken. However, the long‐term impact of clinically healed tattoos on this has never been studied. The aim was to investigate the long‐term effect on the skin barrier function in normal tattoos and examples of tattoos with chronic inflammatory complication.

Methods

Participants were recruited from the “Tattoo clinic” of the Dermatological Department on Bispebjerg Hospital in Denmark, where patients with complicated tattoo reactions are treated. Transepidermal water loss (TEWL), conductance, capacitance, and pH were measured in tattooed skin with regional control measurements in normal non‐tattooed skin. Natural moisturizing factor (NMF) was measured in collected tape strips.

Results

Twenty six individuals with 28 tattoos were included, that is, 23 normal tattoos without any pathologic reaction and 5 tattoos with chronic inflammatory complications. No significant differences were found in tattooed versus non‐tattooed skin with respect to TEWL (median values 6.6 vs 7.2 g/m2/h), conductance (76 vs 78 a.u.), pH (5.94 vs 5.79), and NMF (0.58 vs 0.59 mmol/g protein). Capacitance (64 vs 57 a.u.) was higher in tattooed skin compared to non‐tattooed skin (P = 0.006). Similar results were found in tattoos with inflammatory reactions.

Conclusion

Overall, skin tattoos do not affect the long‐term skin barrier function markedly. The skin capacitance was, however, affected in tattooed skin areas compared to non‐tattooed skin areas.
A multilocus phylogenetic framework of the tribe Aeromachini (Lepidoptera: Hesperiidae: Hesperiinae), with implications for taxonomy and biogeography
Authors: Huang Zhen‐Fu , Chiba Hideyuki , Jin Ju , Kizhakke Athulya Girish , Wang Min , Kunte Krushnamegh , Fan Xiao‐Ling
Published: January 2019

The Oriental tribe Aeromachini (Lepidoptera: Hesperiidae: Hesperiinae) is diverse and widespread, but its monophyly and circumscription remain unresolved. In this study, we inferred phylogenetic relationships within the tribe using two mitochondrial (16S and COI‐COII) and two nuclear genes (EF‐1α and Wingless) from 71 samples representing all of the known genera of Aeromachini (s.l.). Phylogenetic topologies obtained from two model‐based methods (maximum‐likelihood and Bayesian inference) were largely congruent, showing that Aeromachini was monophyletic. Many genera within Aeromachini were polyphyletic, especially Arnetta, Thoressa, Ampittia and Sovia. Based on these results, we propose a new classification consisting of 14 genera, of which two are newly described: Halpemorpha gen.n. and Praethoressa gen.n. Ampittia and Ochus are restructured, with: (i) Ampittia nana and Ampittia dalailama moved to Aeromachus, (ii) new combinations proposed for the remaining Ampittia species, and (iii) a new combination, Ampittia subvittatus comb.n., proposed. The Oriental members of the genus Arnetta belong to this tribe, but the African Arnetta hyposticta was found to be embedded into the outgroup and closely related to Isoteinon. We propose that hyposticta be reinstated in the genus Galerga Mabille, along with two other African species (fito and ellipsis). Thoressa is polyphyletic, with three distinct lineages. The type species Thoressa masoni forms a clade closely related to the sister genera Sebastonyma and Parasovia. We thus describe Praethoressa gen.n. to include the species varia (formerly of Thoressa), and transfer the remaining Thoressa to Pedesta, which is confirmed as a valid genus. Although the relationships of some genera remained unsolved in our work, the present phylogenetic hypothesis will serve as a reference for further studies. A secondary calibration was used to estimate the divergence time, which indicated that the diversification of Aeromachini started in the late Eocene and early Oligocene (c. 34.22 Ma). Further, ancestral range estimates indicated that the common ancestor of Aeromachini originated in Southeast Asia. Diversification in situ and range expansion to adjacent areas have played essential roles in the evolution of Aeromachini, but founder‐event speciation and vicariance also have likely been important factors in shaping the biogeographical history of this tribe.

This published work has been registered on ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:AA11191A-A4E2-47C5-B47B-445E6A2A9E5D.
Improved Priority‐Flood method for depression filling by redundant calculation optimization in local micro‐relief areas
Authors: Xiong Li‐Yang , Jiang Ru‐Qiao , Lu Qing‐Hui , Yang Bi‐Sheng , Li Fa‐Yuan , Tang Guo‐An
Published: January 2019

Depression filling is a critical step in distributed hydrological modeling using digital elevation models (DEMs). The traditional Priority‐Flood (PF) approach is widely used due to its relatively high efficiency when dealing with a small‐sized DEM. However, it seems inadequate and inefficient when dealing with large high‐resolution DEMs. In this work, we examined the relationship between the PF algorithm calculation process and the topographical characteristics of depressions, and found significant redundant calculations in the local micro‐relief areas in the conventional PF algorithm. As such calculations require more time when dealing with large DEMs, we thus propose a new variant of the PF algorithm, wherein redundant points and calculations are recognized and eliminated based on the local micro‐relief water‐flow characteristics of the depression‐filling process. In addition, depressions and flatlands were optimally processed by a quick queue to improve the efficiency of the process. The proposed method was applied and validated in eight case areas using the Shuttle Radar Topography Mission digital elevation model (SRTM‐DEM) with 1 arc‐second resolution. These selected areas have different data sizes. A comparative analysis among the proposed method, the Wang and Liu‐based PF, the improved Barnes‐based PF, the improved Zhou‐based PF, and the Planchon and Darboux (P&D) algorithms was conducted to evaluate the accuracy and efficiency of the proposed algorithm. The results showed that the proposed algorithm is 43.2% (maximum) faster than Wang and Liu's variant of the PF method, with an average of 31.8%. In addition, the proposed algorithm achieved similar performance to the improved Zhou‐based PF algorithm, though our algorithm has the advantage of being simpler. The optimal strategies using the proposed algorithm can be employed in various landforms with high efficiency. The proposed method can also achieve good depression filling, even with large amounts of DEM data.
Mitochondrial complex II of plants: subunit composition, assembly, and function in respiration and signaling
Authors: Huang Shaobai , Braun Hans‐Peter , Gawryluk Ryan M. R. , Millar A. Harvey
Published: January 2019

Complex II [succinate dehydrogenase (succinate‐ubiquinone oxidoreductase); EC 1.3.5.1; SDH] is the only enzyme shared by both the electron transport chain and the tricarboxylic acid (TCA) cycle in mitochondria. Complex II in plants is considered unusual because of its accessory subunits (SDH5–SDH8), in addition to the catalytic subunits of SDH found in all eukaryotes (SDH1–SDH4). Here, we review compositional and phylogenetic analysis and biochemical dissection studies to both clarify the presence and propose a role for these subunits. We also consider the wider functional and phylogenetic evidence for SDH assembly factors and the reports from plants on the control of SDH1 flavination and SDH1–SDH2 interaction. Plant complex II has been shown to influence stomatal opening, the plant defense response and reactive oxygen species‐dependent stress responses. Signaling molecules such as salicyclic acid (SA) and nitric oxide (NO) are also reported to interact with the ubiquinone (UQ) binding site of SDH, influencing signaling transduction in plants. Future directions for SDH research in plants and the specific roles of its different subunits and assembly factors are suggested, including the potential for reverse electron transport to explain the succinate‐dependent production of reactive oxygen species in plants and new avenues to explore the evolution of plant mitochondrial complex II and its utility.
Characterizing nutrient dynamics with relation to changes in partial pressure of CO2 in a tropical sewage‐fed aquaculture pond situated in a Ramsar wetland
Authors: Bhattacharyya Sourav , Hazra Sugata , Das Sourav , Samanta Sourav , Mukhopadhyay Anirban , Dutta Dibyendu , Choudhury S. B. , Chanda Abhra
Published: January 2019

The changes in nutrient dynamics (nitrate, ammonium, silicate, phosphate and iron concentration) vis‐à‐vis partial pressure of CO2 in water [pCO2(water)] from tropical sewage‐fed aquaculture ponds (East Kolkota Wetlands, India) were analysed by means of a microcosm. A significant relationship between these nutrient’s removal from the system and reduction in pCO2(water) was observed (with few exceptions). These water bodies acted as significant sources of CO2 in pre‐monsoon and monsoon seasons despite having substantial quantity of chlorophyll‐a to make it a net autotrophic system. The study revealed that if conditions favourable for optimum photosynthesis can be maintained in these ponds, the CO2 source character of these ponds can be reversed. In the post‐monsoon season, when the pH of the water column was high, the system acted as sink for CO2 which suggests the use of lime to prevent these systems from becoming hypereutrophic and carbon source at the same time.
Barriers Associated With Evidence‐Based Practice Among Nurses in Low‐ and Middle‐Income Countries: A Systematic Review
Authors: Shayan Shah Jahan , Kiwanuka Frank , Nakaye Zainah
Published: January 2019

Background

Evidence‐based practice (EBP) is both a goal and an approach that requires a combination of clinical experience with the most credible recent research evidence when making decisions in healthcare practice. The approach has been widely embraced; however, an evidence‐to‐practice gap still exists.

Aim

To assess barriers to EBP among nurses in low‐ and middle‐income countries.

Methods

This review conforms to the PRISMA statement. Databases PubMed, Scopus, EMBASE, and Web of Science/Knowledge were searched using a combination of keywords that included “barriers,” “evidence‐based practice,” and “nurses.” The references of the selected articles were also hand‐searched to obtain additional relevant articles. Studies published in peer‐reviewed journals in English between 2000 and 2018 were included in the review.

Results

Sixteen articles were included in the analysis, with a total number of 8,409 participants. Both qualitative and quantitative studies were included in the review. Three main themes emerged from eight categories found. The three main themes were institutional‐related barriers, interdisciplinary barriers, and nurse‐related barriers. The theme of institutional‐related barriers emerged from four categories, which included scant resources, limited access to information, inadequate staffing, and lack of institutional support. The theme of interdisciplinary barriers emerged from subcategories that included lack of communication between academic and clinical practice environments, inconsistency between education and practice in the nursing discipline, lack of teamwork, and the public's negative image about the nursing profession. Finally, the theme of nurse‐related barriers emerged from categories including perceived limitations in the scope of nurses’ practice, time, knowledge of EBP, and individual‐related barriers.

Linking Evidence to Action

These findings may guide the design of future interventions aimed at fostering EBP. Implementing EBP in practice should be systematic and requires institutional will and interdisciplinary and individual commitment. It should be a collective goal and a win‐win situation for nurses, clinicians, and healthcare organizations.
The Optimization of Zakat Maal Management in Baubau City
Authors: Sujana I Wayan , Gamsir Samdin , Nusantara Ambo Wonua
Published: January 2019

This research aims to know: (1) optimization of the management of zakat maal seen from the aspect of Muzakki, roles, and mustahik on the BAZNAS city of Baubau, (2) Factors that determine the optimization of the management of zakat wealth (Maal) in the city of Baubau (3) The optimization model of zakat wealth (Maal) management in the city of Baubau. The results showed that: (1) Management of zakat wealth (maal) in the city of Baubau is not optimal (2) The factors that determine the optimal management of zakat wealth consist of: (a) supporting aspects of zakat collection and distribution, (b) constraints collection and distribution of zakat, (3) The optimization model of zakat wealth management (maal) in this study is that BAZNAS needs to collaborate with all elements starting from the government, Ministry of Religion, and Scholar so that the management of zakat wealth can be maximized both in collection and distribution efforts. establish good relations with muzakki and mustahik.
Functional assessment of triheteromeric NMDA receptors containing a human variant associated with epilepsy
Authors: Marwick Katie F. M. , Hansen Kasper B. , Skehel Paul A. , Hardingham Giles E. , Wyllie David J. A.
Published: January 2019

Key points

NMDA receptors are neurotransmitter‐gated ion channels that are critically involved in brain cell communication

Variations in genes encoding NMDA receptor subunits have been found in a range of neurodevelopmental disorders.

We investigated a de novo genetic variant found in patients with epileptic encephalopathy that changes a residue located in the ion channel pore of the GluN2A NMDA receptor subunit.

We found that this variant (GluN2AN615K) impairs physiologically important receptor properties: it markedly reduces Mg2+ blockade and channel conductance, even for receptors in which one GluN2AN615K is co‐assembled with one wild‐type GluN2A subunit.

Our findings are consistent with the GluN2AN615K mutation being the primary cause of the severe neurodevelopmental disorder in carriers.

NMDA receptors are ionotropic calcium‐permeable glutamate receptors with a voltage‐dependence mediated by blockade by Mg2+. Their activation is important in signal transduction, as well as synapse formation and maintenance. Two unrelated individuals with epileptic encephalopathy carry a de novo variant in the gene encoding the GluN2A NMDA receptor subunit: a N615K missense variant in the M2 pore helix (GRIN2AC1845A). We hypothesized that this variant underlies the neurodevelopmental disorders in carriers and explored its functional consequences by electrophysiological analysis in heterologous systems. We focused on GluN2AN615K co‐expressed with wild‐type GluN2 subunits in physiologically relevant triheteromeric NMDA receptors containing two GluN1 and two distinct GluN2 subunits, whereas previous studies have investigated the impact of the variant in diheteromeric NMDA receptors with two GluN1 and two identical GluN2 subunits. We found that GluN2AN615K‐containing triheteromers showed markedly reduced Mg2+ blockade, with a value intermediate between GluN2AN615K diheteromers and wild‐type NMDA receptors. Single‐channel conductance was reduced by four‐fold in GluN2AN615K diheteromers, again with an intermediate value in GluN2AN615K‐containing triheteromers. Glutamate deactivation rates were unaffected. Furthermore, we expressed GluN2AN615K in cultured primary mouse cortical neurons, observing a decrease in Mg2+ blockade and reduction in current density, confirming that the variant continues to have significant functional impact in neuronal systems. Our results demonstrate that the GluN2AN615K variant has substantial effects on NMDA receptor properties fundamental to the roles of the receptor in synaptic plasticity, even when expressed alongside wild‐type subunits. This work strengthens the evidence indicating that the GluN2AN615K variant underlies the disabling neurodevelopmental phenotype in carriers.
Enhanced History Matching of Gas Reservoirs With an Aquifer Using the Combination of Discrete Cosine Transform and Level Set Method in ES-MDA
Authors: Kim Sungil , Jung Hyungsik , Choe Jonggeun
Published: January 2019

Reservoir characterization is a process to make dependable reservoir models using available reservoir information. There are promising ensemble-based methods such as ensemble Kalman filter (EnKF), ensemble smoother (ES), and ensemble smoother with multiple data assimilation (ES-MDA). ES-MDA is an iterative version of ES with inflated covariance matrix of measurement errors. It provides efficient and consistent global updates compared to EnKF and ES. Ensemble-based method might not work properly for channel reservoirs because its parameters are highly non-Gaussian. Thus, various parameterization methods are suggested in previous studies to handle nonlinear and non-Gaussian parameters. Discrete cosine transform (DCT) can figure out essential channel information, whereas level set method (LSM) has advantages on detailed channel border analysis in grid scale transforming parameters into Gaussianity. However, DCT and LSM have weaknesses when they are applied separately on channel reservoirs. Therefore, we propose a properly designed combination algorithm using DCT and LSM in ES-MDA. When DCT and LSM agree with each other on facies update results, a grid has relevant facies naturally. If not, facies is assigned depending on the average facies probability map from DCT and LSM. By doing so, they work in supplementary way preventing from wrong or biased decision on facies. Consequently, the proposed method presents not only stable channel properties such as connectivity and continuity but also similar pattern with the true. It also gives trustworthy future predictions of gas and water productions due to well-matched facies distribution according to the reference.
Scaling Sealing Effectiveness in a Stator–Rotor Cavity for Differing Blade Spans
Authors: Berdanier Reid A. , Monge-Concepción Iván , Knisely Brian F. , Barringer Michael D. , Thole Karen A. , Grover Eric A.
Published: January 2019

As engine development continues to advance toward increased efficiency and reduced fuel consumption, efficient use of compressor bypass cooling flow becomes increasingly important. In particular, optimal use of compressor bypass flow yields an overall reduction of harmful emissions. Cooling flows used for cavity sealing between stages are critical to the engine and must be maintained to prevent damaging ingestion from the hot gas path. To assess cavity seals, the present study utilizes a one-stage turbine with true-scale engine hardware operated at engine-representative rotational Reynolds number and Mach number. Past experiments have made use of part-span (PS) rather than full-span (FS) blades to reduce flow rate requirements for the test rig; however, such decisions raise questions about potential influences of the blade span on sealing effectiveness measurements in the rim cavity. For this study, a tracer gas facilitates sealing effectiveness measurements in the rim cavity to compare data collected with FS engine airfoils and simplified, PS airfoils. The results from this study show sealing effectiveness does not scale as a function of relative purge flow with respect to main gas path flow rate when airfoil span is changed. However, scaling the sealing effectiveness for differing spans can be achieved if the fully purged flow rate is known. Results also suggest reductions of purge flow may have a relatively small loss of seal performance if the design is already near a fully purged condition. Rotor tip clearance is shown to have no effect on measured sealing effectiveness.
Expanding the Solution Space in Engineering Design Education: A Simulation-Based Investigation of Product Dissection
Authors: Alsager Alzayed Mohammad , McComb Christopher , Hunter Samuel T. , Miller Scarlett R.
Published: January 2019

Product dissection has been highlighted as an effective means of interacting with example products in order to produce creative outcomes. While product dissection is often conducted as a team in engineering design education, the research on the effectiveness of product dissection activities has been primarily limited to individuals. Thus, the purpose of this study was to investigate the impact of the type(s) of product dissected in a team environment on encouraging creative design outcomes (variety, novelty, and quantity) and the underlying influence of educational level and dissection modality on these effects. This was accomplished through a computational simulation of 14,000 teams of noninteracting brainstorming individuals generated by a statistical bootstrapping technique using a design repository of 931 ideas generated by first-year and senior engineering students. The results of the study highlight the importance of educational level, dissection modality, and the number of products dissected on team design outcomes. Specifically, virtual dissection encouraged the exploration of more novel solutions across both educational levels. However, physical dissection encouraged the exploration of a larger variety and quantity of ideas for senior teams while virtual dissection encouraged the same in first-year teams. Finally, dissecting different types of products allowed teams to explore a larger solution space. The findings presented in this study can lead to a better understanding of how to deploy product dissection modules in engineering design education in order to drive creative design outcomes.
Effects of Flash Boiling in Nozzle Flow of GDI Injector on Air/Fuel Mixture
Authors: Ishii Eiji , Yoshimura Kazuki , Koshizuka Seiichi , Sekine Akihiro , Sugihara Shota
Published: January 2019

The widths of fuel plumes around nozzle outlets expanded due to flash boiling during the nozzle flow. In some sprays, the length (penetration) of the air/fuel mixture increased due to the flash boiling. A cavitation model was incorporated in a simulation of the fuel spray integrating a simulation of the nozzle flow with a simulation of the air/fuel mixture. The simulation was applied to fuel sprays from a gasoline direct-injection injector; six nozzles were placed on an orifice cup in axial symmetry. Expansions of the plumes (in terms of width) around the nozzle outlets due to flash boiling and extension of spray penetration qualitatively agreed with the measured ones. Effects of the expansions of the plumes due to flash boiling on spray-penetration distance were also studied. The result of that study indicated that interactions between the expanded plumes around the nozzle outlets cause the spray shape of the air/fuel mixtures to thin, thereby extending the penetration of the spray.
Heavy Duty Engine Piston Cooling Gallery Oil Filling Ratio Measurement and Comparison of Results With Simulation
Authors: Chen Yu , Moghe Shashank
Published: January 2019

Pistons for heavy duty diesel applications endure high thermal loads and therefore result in reduced durability. Pistons for such heavy duty applications are generally designed with an internal oil gallery — called the piston cooling gallery (PCG) — where the intent is to reduce the piston crown temperatures through forced convection cooling and thereby ensure the durability of the piston. One of the key factors influencing the efficiency of such a heat-transfer process is the volume fraction of oil inside the piston cooling gallery — defined as the filling ratio (FR) — during engine operation.

As a part of this study, a motoring engine measurement system was developed to measure the piston filling ratio of an inline-6 production heavy duty engine. In this system, multiple high precision pressure sensors were applied to the piston cooling gallery and a linkage was designed and fabricated to transfer the piston cooling gallery oil pressure signal out of the motoring engine. This pressure information was then correlated with the oil filling ratio through a series of calibration runs with known oil quantity in the piston cooling gallery. This proposed method can be used to measure the piston cooling gallery oil filling ratio for heavy duty engine pistons. A preliminary transient Computational Fluid Dynamics (CFD) analysis was performed to identify the filling ratio and transient pressures at the corresponding transducer locations in the piston cooling gallery for one of the motoring test operating speeds (1200 RPM). A mesh dependency study was performed for the CFD analysis and the results were compared against those from the motoring test.
Combustion Ionization for Detection of Misfire, Knock, and Sporadic Pre-Ignition in a Gasoline Direct Injection Engine
Authors: Ayad Samuel , Sharma Swapnil , Verma Rohan , Henein Naeim
Published: January 2019

Detection of combustion related phenomena such as misfire, knock and sporadic preignition is very important for the development of electronic controls needed for the gasoline direct injection engines to meet the production goals in power, fuel economy, and low emissions.

This paper applies several types of combustion ionization sensors, and a pressure transducer that directly sense the in-cylinder combustion, and the knock sensor which is an accelerometer that detects the impact of combustion on engine structure vibration. Experimental investigations were conducted on a turbocharged four cylinders gasoline direct injection engine under operating conditions that produce the above phenomena. One of the cylinders is instrumented with a Piezo quartz pressure transducer, MSFI (Multi sensing fuel injector), a standalone ion current probe, and a spark plug applied to act as an ion current sensor. A comparison is made between the capabilities of the pressure transducer, ion current sensors, and the knock sensor in detecting the above phenomena. The signals from in-cylinder combustion sensors give more accurate information about combustion than the knock sensor. As far as the feasibility and cost of their application in production vehicles the spark plug sensor and MSFI appear to be the most favorable, followed by the Standalone mounted sensor which is an addition to the engine.
Experimental Investigations of Hydrogen-Natural Gas Engines for Maritime Applications
Authors: Sapra Harsh D. , Linden Youri , van Sluijs Wim , Godjevac Milinko , Visser Klaas
Published: January 2019

A novel ship propulsion concept employs natural gas to reduce ship emissions and improve overall ship propulsion efficiency. This concept proposes a serial integration of Solid Oxide Fuel Cell (SOFC) and a natural gas engine, while anode-off gas (gas at the fuel cell exhaust) is used in the natural gas engine. This study focusses on SOFC-gas engine integration by experimentally analyzing the effects of adding hydrogen, which is the main combustible component of the fuel cell anode-off gas, in marine natural gas engines. The overall challenge is to employ the anode-off gas to improve the performance of marine natural gas engines. To study the effects of anode-off gas combustion in natural gas engines, experiments with hydrogen addition in a marine natural gas engine of 500 kW rated power were performed. Natural gas was replaced with 10 % and 20 % of hydrogen, by volume, without any penalties in terms of output power.

We found that the high combustion rate of hydrogen improved combustion stability, which allowed for better air-excess ratio control. Thus allowing leaning to higher air-excess ratios and extending the, otherwise, limited operating window. Hydrogen addition also improved brake thermal efficiency by 1.2 %, while keeping NOx emissions below the maritime emission regulations. The improvement in engine efficiency with a larger operating window may help improve the load-taking capabilities of marine natural gas engines.
Combustion Variability Model for Control of Injection Timing for Diesel Exhaust Heating
Authors: Bieniek Mitchell , Stefanopoulou Anna , Hoard John , Fulton Brien , Van Nieuwstadt Michiel
Published: January 2019

Diesel engine emission cycle data shows that major portions of cycle emissions are produced at the beginning of the test, when the aftertreatment is not at operational temperature (prior to “light-off”) [1]. To reduce diesel emissions, aggressive combustion phasing retard via injection timing can be used to achieve faster aftertreatment light-off, but this method is limited because of vibration and harshness concerns associated with the combustion variability induced by the late combustion phasing. In order to achieve aggressive exhaust heating while mitigating combustion variability concerns, the premise of controlling combustion variability is explored. In particular, a controller will use real-time measurements of combustion features and control injection timing to maintain an acceptable level of combustion variability. The closed loop controller tuning requires an understanding of combustion variability behavior as a function of combustion phasing retard. The characterization of combustion variability using engine experiments is presented, and the findings are used to develop a control-oriented combustion variability model consisting of regressions of the statistics of IMEP as a function of fuel and timing offsets.
Development of a New Four Valve Cylinder Head to Increase the Efficiency of a Worldwide High Reliable Gas Engine
Authors: Herdin Rüdiger , Herdin Andreas , Alten Hans , Herdin Günther , Mairegger Dominik
Published: January 2019

Electrical efficiency is an important factor for most of the owners of gas engines. To reach a high electrical efficiency, engine manufacturers use four valve cylinder head technology on new designed engines. The change from two valve to four valve technology, in combination with optimized charge motion, can achieve an increase of electrical efficiency up to 2.5%. A significant number of engines in the market are only equipped with two valve cylinder heads, thus leaving potential to reduce carbon emissions and fuel consumption.

The scope of the paper applies to the modernization of an already well established gas engine series available on the market with a power range of 500–1100kW [1].

In the first step, the potentials were considered purely in the context of a change in configuration of the spark plug, to pre-chamber spark plug. As second step an optimization of the ports was examined. Due to the pre-existing high level of development of the combustion stage, combined with an adaption of the boost charging system, an improvement of almost 2.5% was achieved. According to data sheets, modern gas engines within this power range have efficiencies in the range of ηe ∼ 44%. The project team therefore proceeded to develop a new cylinder head along with new design leading to a better combustion. Minimizing changes around the periphery of the engine was a prerequisite in order to complete these on site as part of the 30.000-hour service. Intake- as well as exhaustport geometries were optimized with the aid of CFD tools, such that swirl and flow capacity values achieved their specified objectives. The geometries of the water jacket and valve train were also optimized through a similar methodology. These changes led to a 7% reduction in gas exchange work, which directly reflect within improved efficiency levels. Altogether, the various measures (including combustion optimization) resulted in an efficiency improvement of about 2.5% leading to an electric efficiency of 42.9%. The first endurance run shows that the mechanics match the expected technical requirements. Very low wear rates despite the increased masses of the valve train could be reached due to higher qualities in terms of materials.

The paper focuses particularly on the flow optimization in conjunction with the variables surrounding the mechanic design. Finally, the test results of the pilot engines are presented alongside an economic analysis.
CFD Analysis of Diesel-Methane Dual Fuel Low Temperature Combustion at Low Load and High Methane Substitution
Authors: Aniello Andrea , Bartolucci Lorenzo , Cordiner Stefano , Mulone Vincenzo , Krishnan Sundar R. , Srinivasan Kalyan K.
Published: January 2019

Over the last few decades, emissions regulations for internal combustion engines have become increasingly restrictive, pushing researchers around the world to exploit innovative propulsion solutions. Among them, the dual fuel low temperature combustion (LTC) strategy has proven capable of reducing fuel consumption and while meeting emissions regulations for oxides of nitrogen (NOx) and particulate matter (PM) without problematic aftertreatment systems. However, further investigations are still needed to reduce engine-out hydrocarbon (HC) and carbon monoxide (CO) emissions as well as to extend the operational range and to further improve the performance and efficiency of dual-fuel engines.

In this scenario, the present study focuses on numerical simulation of fumigated methane-diesel dual fuel LTC in a single-cylinder research engine (SCRE) operating at low load and high methane percent energy substitution (PES). Results are validated against experimental cylinder pressure and apparent heat release rate (AHRR) data. A 3D full-cylinder RANS simulation is used to thoroughly understand the influence of the start of injection (SOI) of diesel fuel on the overall combustion behavior, clarifying the causes of AHRR transition from two-stage AHRR at late SOIs to single-stage AHRR at early SOIs, low temperature heat release (LTHR) behavior, as well as high HC production.

The numerical campaign shows that it is crucial to reliably represent the interaction between the diesel spray and the in-cylinder charge to match both local and overall methane energy fraction, which in turn, ensures a proper representation of the whole combustion. To that aim, even a slight deviation (∼3%) of the trapped mass or of the thermodynamic conditions would compromise the numerical accuracy, highlighting the importance of properly capturing all the phenomena occurring during the engine cycle.

The comparison between numerical and experimental AHRR curves shows the capability of the numerical framework proposed to correctly represent the dual-fuel combustion process, including low temperature heat release (LTHR) and the transition from two-stage to single stage AHRR with advancing SOI. The numerical simulations allow for quantitative evaluation of the residence time of vapor-phase diesel fuel inside the combustion chamber and at the same time tracking the evolution of local diesel mass fraction during ignition delay — showing their influence on the LTHR phenomena. Oxidation regions of diesel and ignition points of methane are also displayed for each case, clarifying the reasons for the observed differences in combustion evolution at different SOIs.
Evaluation of Strategies for Highly Transient Operation of Diesel-Gas Engines
Authors: Malin Maximilian , Redtenbacher Christoph , Lurf Gottfried , Wermuth Nicole , Wimmer Andreas
Published: January 2019

The balancing of the electric grid has become more challenging due to the expansion of fluctuating renewable energy sources for electric power generation. The importance of power plants driven by internal combustion engines will increase since they can react flexibly and quickly to changes in the energy demand. With regard to the emission of pollutants and CO2, gas fueled engines are favored for gensets. However, it is more challenging to meet the dynamic load requirements with a gas engine than with a conventional diesel engine because the load acceptance of the gas engine is limited by the occurrence of knocking combustion.

Dual fuel engines are a good compromise between these two engine concepts; they can use gaseous fuel during steady state engine operation and increase the diesel share during transient modes to improve the dynamic behavior. The high number of degrees of freedom of dual fuel combustion concepts requires advanced operating strategies.

The aim of this paper is to investigate and evaluate strategies to improve the transient behavior of a 20-cylinder large bore diesel-gas engine (displacement 6.24 dm3 per cylinder) for a genset application. In the investigations, the latest turbocharging technology is applied in combination with a turbine waste gate. A wide range diesel injector that covers the whole diesel injection range of approximately 1 % to 100 % diesel fraction1 of the rated power fuel mass provides the basis for the most flexible diesel injection. A 1D simulation tool was used to model and optimize the genset in transient operation. The combustion process was simulated with Vibe heat release rate models. The optimized transient engine operating strategies were validated on a highly dynamic single cylinder research engine test bed.

The paper provides a comparison of different strategies that use these technologies to improve the dynamic behavior of the genset in island mode operation during a 50 % load step. Key to meeting the challenging requirements is an optimized diesel injection strategy or even a switch from gas operation mode to diesel operation mode during the load step. Based on the results of simulation and engine testing, potential ways to minimize engine speed drop and recovery time after the load demand increase are evaluated.
A Study to Determine Factors That Have Influence on the Propensity of Natural LSPI Occurring in GTDI Engines
Authors: Sethi Paras , Passow Eric , Karrip Kimm , Maschewske Max , Bieneman Jason , Truckel Paul
Published: January 2019

There are many articles and papers published about the developments in engine downsizing as an effective means in reducing vehicle fuel consumption while improving engine performance. The increase in performance of gasoline turbo charged direct injected (GTDI) engines, in conjunction with diverse vehicle platform performance targets (i.e. towing capability) and higher gear transmissions pushes the engine to operate with higher torques at lower engine speeds. This operating condition has increased the propensity of an abnormal combustion event, known as Low Speed Pre-Ignition (LSPI) or Stochastic Pre-Ignition (SPI). The power cylinder unit (PCU) components exposed to this pre-ignition event can experience failure. The engine manufacturers, as well as MAHLE, continue to ensure engine and PCU component survivability against LSPI by performing life cycle robustness testing. MAHLE’s research of LSPI continues to focus on the robustness of PCU components in the presence of LSPI events, as well as investigating design developments that have the potential to minimize the propensity of LSPI to occur. The test procedure development for evaluating natural LSPI events will be presented. Various test results and parameter sensitivities that were documented during this procedure development, along with the many challenges associated with engine performance repeatability will be discussed. Parameters that were found to influence LSPI propensity, as well as parameters that were found not to influence LSPI propensity will be discussed.