bluuebunny/crossref_metadata_2025 huggingface dataset:
Anatomical site variation of water content in human skin measured by the Epsilon: A pilot study
Authors: Logger Jade G. M. , Münchhoff Christina U. , Olydam Jill I. , Peppelman Malou , Van Erp Piet E. J.
Published: January 2019

Background

This pilot study aimed to investigate the anatomical site variation of water content of the stratum corneum (SC) on the body by measuring skin capacitance with the Epsilon, a new generation corneometer with multiple sensors. Secondly, values of the Epsilon were compared to values measured by conventional single sensor corneometers.

Methods

The hydration status of SC was measured in 15 healthy Caucasian volunteers with the Epsilon at five body sites (cheek, lower forearm, mid‐calf, lower back and abdomen). Transepidermal water loss (TEWL) was measured with the Aquaflux to get more insight into the condition of the skin barrier. A literature search was performed to compare Epsilon values with conventional corneometers.

Results

The tested anatomical locations showed significant differences in water content (P < 0.001) with large interindividual variations; highest values were found in the cheek (11.64ε) and lowest values in the mid‐calf (4.43ε). No correlation between water content and TEWL was found. In general, Epsilon values were lower compared to values of conventional corneometers, with a similar trend.

Conclusion

This pilot study showed significant variations in water content at different skin locations measured by the Epsilon. Moreover, the Epsilon measured consistent lower values compared to single sensor corneometers. Further validation of the device is recommended.
Divergent host use among cryptic species in the fungivorous ciid beetleOctotemnus laminifrons(Motschulsky, 1860), with descriptions of three new species from Japan
Authors: Kobayashi Takuya , Sota Teiji
Published: January 2019

Insect–host fungus associations are important ecological features that affect population dynamics and interspecific interactions. However, details of host fungus relationships in fungivorous beetles remain unclear due to incompletely revised taxonomy and insufficient host records. We conducted a taxonomic study of the ciid beetleOctotemnus laminifrons(Coleoptera: Ciidae) and its cryptic species in Japan and investigated fungal host‐use by these ciid beetles. Maximum‐likelihood phylogenetic analysis of mitochondrialcytochrome c oxidase subunit Ifragments and two nuclear markers recovered four well‐supported, reciprocally monophyletic groups among specimens previously identified asO. laminifrons. Quantitative analyses of genital structures revealed diagnostic differences among these four lineages. These molecular and morphological analyses indicate that the ciid beetles currently identified asO. laminifronsactually comprise four species:O. laminifrons(Motschulsky, 1860),O. assimilisKobayashi & Sotasp.n.,O. crassusKobayashi & Sotasp.n.andO. kawanabeiKobayashi & Sotasp.n.Here we provide a redescription and lectotype designation forO. laminifronsand descriptions of the three new species. These species showed different patterns of fungal host‐use among fourTrametesand oneLenzitesspecies. We also studied the phylogenetic relationships among these four species based on restriction‐site associated DNA (RAD) sequence data, which provided a more reliable phylogenetic tree. We discuss shifts in their fungal host use. Our results demonstrate that closely related, congeneric fungivorous insects exhibit different utility patterns for closely related fungal species, a phenomenon that has rarely been reported previously.
An integrative approach elucidates the systematics of Sea Hayward and Cybdelis Boisduval (Lepidoptera: Nymphalidae: Biblidinae)
Authors: Dias Fernando M. S. , Siewert Ricardo R. , Freitas André V. L. , Lamas Gerardo , Magaldi Luiza M. , Mielke Olaf H. H. , Casagrande Mirna M.
Published: January 2019

The systematics of the enigmatic and rather uncommon species of Sea Hayward and Cybdelis Boisduval is assessed through morphological and molecular analyses. The aim of this paper is three‐fold: (i) to ascertain the phylogenetic position of Sea and Cybdelis in Biblidinae; (ii) to determine the evolutionary relationships among species of Sea and Cybdelis; and (iii) to review the taxonomy of Sea and Cybdelis. The result of the molecular analysis recovers Sea sister to Cybdelis, and this clade sister to Eubagina (sensu Lamas, ), rendering Epicaliina (sensu Lamas, ) paraphyletic. A new tribe, Cybdelini trib.n. is erected to include Sea and Cybdelis; the other genera formerly included in Epicaliina (sensu Lamas, ), Eunica Hübner and Sevenia Koçak are assigned to Eunicini trib.rest., and the remaining genera of Biblidinae to other previously recognized tribes, similar to those implicitly proposed by Wahlberg et al. (). The morphological analysis recovers similar results and the following relationships among species of Cybdelis: C. phaesyla (Hübner) (C. boliviana Salvin (C. mnasylus Doubleday (C. petronita Burmeister stat.rest. + C. thrasylla C. Felder & R. Felder stat.rest.))). Sea and Cybdelis are recognized as distinct genera; a new subspecies, S. sophronia jenkinsi Dias, Siewert & Freitas ssp.n., distributed from Venezuela to Bolivia along the Andes eastern foothills, is described; and C. petronita and C. thrasylla are accepted as valid species. Lectotypes for C. boliviana, C. peruviana Staudinger, C. mnasylus, C. thrasylla, C. petronita and C. mnasylus var. meridionalis Hall and a neotype for Vanessa sophronia Godart are designated. Additionally, dichotomous keys and distribution maps to all taxa are provided; male genitalia and hypandria are illustrated for all species; generic characters of the head, labial palpi and legs are illustrated; immature stages of some species also are figured.

The published work has been registered on ZooBank:
http://zoobank.org/urn:lsid:zoobank.org:pub:D8EBB649‐5E9D‐4218‐B1F1‐7A69DA775FD0.
Phloem loading in cucumber: combined symplastic and apoplastic strategies
Authors: Ma Si , Sun Lulu , Sui Xiaolei , Li Yaxin , Chang Ying , Fan Jingwei , Zhang Zhenxian
Published: January 2019

Phloem loading, as the first step of transporting photoassimilates from mesophyll cells to sieve element‐companion cell complex, creates a driving force for long‐distance nutrient transport. Three loading strategies have been proposed: passive symplastic loading, apoplastic loading and symplastic transfer followed by polymer‐trapping of stachyose and raffinose. Although individual species are generally referred to as using a single phloem loading mechanism, it has been suggested that some plants may use more than one, i.e. ‘mixed loading’. Here, by using a combination of electron microscopy, reverse genetics and 14C labeling, loading strategies were studied in cucumber, a polymer‐trapping loading species. The results indicate that intermediary cells (ICs), which mediate polymer‐trapping, and ordinary companion cells, which mediate apoplastic loading, were mainly found in the fifth and third order veins, respectively. Accordingly, a cucumber galactinol synthase gene (CsGolS1) and a sucrose transporter gene (CsSUT2) were expressed mainly in the fifth/third and the third order veins, respectively. Immunolocalization analysis indicated that CsGolS1 was localized in companion cells (CCs) while CsSUT2 was in CCs and sieve elements (SEs). Suppressing CsGolS1 significantly decreased the stachyose level and increased sucrose content, while suppressing CsSUT2 decreased the sucrose level and increased the stachyose content in leaves. After 14CO2 labeling, [14C]sucrose export increased and [14C]stachyose export reduced from petioles in CsGolS1i plants, but [14C]sucrose export decreased and [14C]stachyose export increased into petioles in CsSUT2i plants. Similar results were also observed after pre‐treating the CsGolS1i leaves with PCMBS (transporter inhibitor). These results demonstrate that cucumber phloem loading depends on both polymer‐trapping and apoplastic loading strategies.
Arabidopsis PCaP2 modulates the phosphatidylinositol 4,5‐bisphosphate signal on the plasma membrane and attenuates root hair elongation
Authors: Kato Mariko , Tsuge Tomohiko , Maeshima Masayoshi , Aoyama Takashi
Published: January 2019

Phosphatidylinositol 4,5‐bisphosphate [PtdIns(4,5)P2] serves as a subcellular signal on the plasma membrane, mediating various cell‐polarized phenomena including polar cell growth. Here, we investigated the involvement of Arabidopsis thaliana PCaP2, a plant‐unique plasma membrane protein with phosphoinositide‐binding activity, in PtdIns(4,5)P2 signaling for root hair tip growth. The long‐root‐hair phenotype of the pcap2 knockdown mutant was found to stem from its higher average root hair elongation rate compared with the wild type and to counteract the low average rate caused by a defect in the PtdIns(4,5)P2‐producing enzyme gene PIP5K3. On the plasma membrane of elongating root hairs, the PCaP2 promoter‐driven PCaP2–green fluorescent protein (GFP), which complemented the pcap2 mutant phenotype, overlapped with the PtdIns(4,5)P2 marker 2xCHERRY‐2xPHPLC in the subapical region, but not at the apex, suggesting that PCaP2 attenuates root hair elongation via PtdIns(4,5)P2 signaling on the subapical plasma membrane. Consistent with this, a GFP fusion with the PCaP2 phosphoinositide‐binding domain PCaP2N23, root hair‐specific overexpression of which caused a low average root hair elongation rate, localized more intense to the subapical plasma membrane than to the apical plasma membrane similar to PCaP2–GFP. Inducibly overexpressed PCaP2–GFP, but not its derivative lacking the PCaP2N23 domain, replaced 2xCHERRY‐2xPHPLC on the plasma membrane in root meristematic epidermal cells, and suppressed FM4‐64 internalization in elongating root hairs. Moreover, inducibly overexpressed PCaP2 arrested an endocytic process of PIN2–GFP recycling. Based on these results, we conclude that PCaP2 functions as a negative modulator of PtdIns(4,5)P2 signaling on the subapical plasma membrane probably through competitive binding to PtdIns(4,5)P2 and attenuates root hair elongation.
Predisposing factors for anti‐D immune response in D− patients with chronic liver disease transfused with D+ platelet concentrates
Authors: Burin des Roziers Nicolas , Chadebech Philippe , Malard Lucile , Vingert Benoit , Gallon Philippe , Samuel Didier , Djoudi Rachid , Fillet Anne‐Marie , Pirenne France
Published: January 2019

BACKGROUND

Recent reports have indicated that the risk of anti‐D alloimmunization following D‐incompatible platelet (PLT) transfusion is low in hematology and oncology patients. We investigated the rate of anti‐D alloimmunization in RhD‐negative (D−) patients with chronic liver disease transfused with D+ platelet concentrates (PCs) and the factors involved, at a liver transplant (LT) center.

STUDY DESIGN AND METHODS

We reviewed the blood bank database from January 2003 to October 2016.

D− patients who had received D+ PLT transfusions were eligible if they had undergone antibody screening at least 28 days after the first D+ PC transfusion, had no previous or concomitant exposure to D+ blood products, and had not received anti‐D immunoglobulins.

RESULTS

Six of the 56 eligible patients (10.7%) had anti‐D antibodies. All had received whole blood‐derived PCs. Four of 20 patients (20%) untransplanted or transfused before LT and only two of 36 patients (5.6%) transfused during or after LT produced anti‐D antibodies. These two patients were on maintenance immunosuppression based on low‐dose steroids and tacrolimus. The factors identified as significantly associated with anti‐D immune response were the presence of red blood cell immune alloantibodies before D+ PLT transfusion (p = 0.003), and D+ PLT transfusion outside the operative and postoperative (5 days) periods for LT (p = 0.023).

CONCLUSION

D− patients with chronic liver disease transfused with D+ PLTs before LT are at high risk of developing anti‐D antibodies. Preventive measures should be considered for these patients.
Effective treatment and decolonization of a dog infected with carbapenemase (VIM‐2)‐producing Pseudomonas aeruginosa using probiotic and photodynamic therapies
Authors: Sellera Fábio P. , Fernandes Miriam R. , Sabino Caetano P. , de Freitas Laura M. , da Silva Luciano C.B.A. , Pogliani Fabio C. , Ribeiro Martha S. , Hamblin Michael R. , Lincopan Nilton
Published: January 2019

Background

Carbapenem‐resistant bacterial infections are a critical problem in veterinary medicine with limited treatment options.

Objective

To describe effective probiotic and photodynamic therapy of a dog with gut colonization and ear infection caused by a hospital‐associated lineage of carbapenemase (VIM‐2)‐producing Pseudomonas aeruginosa.

Animals

A 5‐year‐old Lhasa apso dog presented with otitis externa.

Methods and materials

Unilateral otitis externa caused by carbapenem‐resistant P. aeruginosa was treated with antimicrobial photodynamic therapy (aPDT) using methylene blue as photosensitizer [wavelength 660 nm, fluence 140 J/cm2, 8 J and 80 s per point (six equidistant points), 100 mW, spot size 0.028 cm2 and fluence rate 3.5 W/cm2]. The isolated bacterial strain also was tested for susceptibility to in vitro aPDT where the survival fraction was quantified by colony forming unit counts after exposure to increasing light doses. For decolonization, probiotic supplements were orally administered (once daily) for 14 days. Effectiveness of probiotics and photodynamic therapy was evaluated by clinical and microbiological culture assays.

Results

Complete resolution of clinical signs was achieved by Day 7 after aPDT. Samples collected immediately and after seven and 14 days following aPDT were negative for VIM‐2‐producing P. aeruginosa. Oral and rectal swabs collected on days 7, 14 and 21 after probiotic therapy, confirmed effective gastrointestinal decolonization.

Conclusions and clinical importance

Combined use of aPDT and probiotics could be a promising therapeutic strategy for treatment of superficial infections produced by carbapenem‐resistant bacteria, while avoiding recurrent infection due to intestinal bacterial carriage of these multidrug‐resistant pathogens.
Lack of radioprotection knowledge and compliance in Norwegian equine ambulatory practice
Authors: Mikkelsen Marthe Aamodt , Ottesen Nina , Knutsen Bjørn Helge , Søvik Åste
Published: January 2019

There is an increasing use of mobile radiographic units in equine ambulatory practices in Norway. Horse owners or handlers often participate in the radiographic examination in a non‐controlled area. The aim of this descriptive, cross‐sectional, survey study was to evaluate the radiation safety and protection in use of mobile radiography, and to identify areas where special attention from the regulatory authorities as well as veterinary educators would be required. A questionnaire was distributed to all equine veterinarians assumed to have access to mobile radiographic units, as part of a formal inspection in cooperation with the Norwegian Radiation Protection Authority. Few practices met the regulatory requirements of notifying the authorities of their radiographic units and designation of a radiation protection officer. The minority of the practices performed periodic quality assurance of their equipment. Many of the practices performed all of their radiographic examinations off‐site. The examinations were most often performed in the aisle outside the horses’ stalls, and few practices established an operating zone. The horse owner or handler participated in the radiographic examination in almost all of the practices. Few practices used dosimeters for determination of the radiation exposure. The study shows that there are major deficits in regulatory compliance in ambulatory equine radiography practices in Norway. The study also suggests that less stringent regulations and supervision may translate into less stringent radioprotection practices.
An approach using a novel phage mix for detecting Pseudomonas aeruginosa in water
Authors: Ezzat Safaa M. , Azzam Mohamed I.
Published: January 2019

The present study aims to integrate the benefits of plaque assay using a novel phage mix with phylogenetic and molecular analysis for detecting Pseudomonas aeruginosa in water. Three phages were isolated and the transmission electron microscope related their morphological resemblance to those of Siphoviridae and Podoviridae families, while molecular analysis showed different cp‐gene sizes. The Phage mix was highly specific (86.0%), and data misleading didn't exceed 14.0% compared to membrane filter assay (39.2%). Time elapsed for test completion required 24 h. Identified P. aeruginosa were verified using 16S‐rDNA. Nucleotide sequence data for both phages and bacteria were submitted to the NCBI GenBank database, USA and gained their accession numbers. Concluding remarks highlight the potential of plaque assay as specific, simple and rapid method. The study recommended future efforts to isolate and characterize new phages for detecting other bacterial pathogens of public health concern to control water pollution and maintain adequate hygiene.
Application of Low-Temperature Phase Change Materials to Enable the Cold Weather Operability of B100 Biodiesel in Diesel Trucks
Authors: Nnaemeka Obiajulu J. , Bibeau Eric L.
Published: January 2019

The use of B100 biodiesel for compression ignition engines during the winter poses a challenge due to gelling and plugging of engine filters and fuel lines. The most common method to prevent this issue is blending it with petroleum diesel and many engine manufacturers limit the biodiesel in blends to 20% or less for warrantee purposes; as low as 5% may be set for winter months. In this research, an experimental analysis is performed using a scaled model of the fuel tank with canola oil as a test fluid in the tank. An insulated tank is subjected to an ambient temperature of −20 °C in an icing tunnel facility with air velocity at 10 m/s. The results show that the time for the oil to drop from 20 °C to 5 °C was increased from 18.6 h to 22.5 and 33 h, respectively, when 4 and 12 tubes containing phase change materials (PCM) were inserted in the tank containing 33 l of canola oil. A numerical model was further formulated to predict the transient temperature of the oil and comparison with experimental results showed excellent agreement. Finally, the developed numerical model was used to simulate different designs to investigate the effect of tank filling level, overall heat transfer coefficient, number of PCM modules, and diameter of PCM modules on the tank performance. The results show that B100 can be implemented in diesel engines in cold climates using a passive approach using engine coolant.
Influence of Swirl and Primary Zone Airflow Rate on the Emissions and Performance of a Liquid-Fueled Gas Turbine Combustor
Authors: Lokini Parneeth , Roshan Dinesh Kumar , Kushari Abhijit
Published: January 2019

This paper presents the results of an experimental study on the influence of swirl number (S) and primary zone airflow rate on the temperature, emission indices of the pollutants, and combustion efficiency in an atmospheric pressure liquid-fueled gas turbine (GT) combustor, equipped with a swirling jet air blast atomizer and operated with Jet A1 fuel. Experiments were conducted at three primary zone air flow rates and three swirl numbers (0.49, 0.86, and 1.32). For all the cases, it was found that the NOx emissions were very low (< 2 g/kg of fuel). At all the swirl numbers, an increase in primary zone airflow led to a nonmonotonous variation in CO while minimally affecting the NOx emissions. However, increase in the swirl number generated relatively higher NOx and lower CO owing to higher temperature resulting from efficient combustion caused by a superior fuel–air mixing. Also, the unburnt hydrocarbons (UHC) was quite high at S = 0.49 because of the unmixedness of fuel and air, and zero at S = 0.86 and 1.32. The combustion efficiency was very low (around 60%) at S = 0.49 while almost 100% at S = 0.86 and 1.32. The study conducted demonstrates a significant dependence of emissions and GT performance on the swirl number governed by the convective time scales and the residence time of the combustible mixture in the combustion zone.
Design and Optimization of Composite Offshore Wind Turbine Blades
Authors: Tarfaoui M. , Shah O. R. , Nachtane M.
Published: January 2019

In order to obtain an optimal design of composite offshore wind turbine blade, take into account all the structural properties and the limiting conditions applied as close as possible to real cases. This work is divided into two stages: the aerodynamic design and the structural design. The optimal blade structural configuration was determined through a parametric study by using a finite element method. The skin thickness, thickness and width of the spar flange, and thickness, location, and length of the front and rear spar web were varied until design criteria were satisfied. The purpose of this article is to provide the designer with all the tools required to model and optimize the blades. The aerodynamic performance has been covered in this study using blade element momentum (BEM) method to calculate the loads applied to the turbine blade during service and extreme stormy conditions, and the finite element analysis was performed by using abaqus code to predict the most critical damage behavior and to apprehend and obtain knowledge of the complex structural behavior of wind turbine blades. The approach developed based on the nonlinear finite element analysis using mean values for the material properties and the failure criteria of Hashin to predict failure modes in large structures and to identify the sensitive zones.
Origami-Based Design of Conceal-and-Reveal Systems
Authors: DeFigueiredo Bryce P. , Pehrson Nathan A. , Tolman Kyler A. , Crampton Erica , Magleby Spencer P. , Howell Larry L.
Published: January 2019

This work introduces a type of motion termed “conceal-and-reveal” which is characterized by a state that protects a payload, a state that exposes the payload, and coupled motions between these two states. As techniques for thick, rigid origami-based engineering designs are being developed, origami is becoming increasingly more attractive as inspiration for complex systems. This paper proposes a process for designing origami-based conceal-and-reveal systems, which can be generalized to design similar thick, rigid origami-based systems. The process is demonstrated through the development of three conceal-and-reveal systems that present a luxury product to the consumer. The three designs also confirm that multiple origami crease patterns can be used to initiate viable approaches to achieving conceal-and-reveal motion.
Accuracy of Diesel Engine Combustion Metrics Over the Full Range of Engine Operating Conditions
Authors: Dowell Peter G. , Burke Richard D. , Akehurst Sam
Published: January 2019

Measuring and analyzing combustion is a critical part of the development of high efficiency and low emitting engines. Faced with changes in legislation such as Real Driving Emissions and the fundamental change in the role of the combustion engine with the introduction of hybrid-electric powertrains, it is essential that combustion analysis can be conducted accurately across the full range of operating conditions. In this work, the sensitivity of five key combustion metrics is investigated with respect to eight necessary assumptions used for single zone Diesel Combustion analysis. The sensitivity was evaluated over the complete operating range of the engine using a combination of experimental and modelling techniques. This provides a holistic understanding of combustion measurement accuracy.

For several metrics, it was found that the sensitivity at the mid speed/load condition was not representative of sensitivity across the full operating range, in particular at low speeds and loads. Peak heat release rate and indicated mean effective pressure were found to be most sensitive to the determination of top dead center (TDC) and the assumption of in-cylinder gas properties. An error of 0.5° in the location of TDC would cause on average a 4.2% error in peak heat release rate. The ratio of specific heats had a strong impact on peak heat release with an error of 8% for using the assumption of a constant value.

A novel method for determining TDC was proposed which combined a filling and emptying simulation with measured data obtained experimentally from an advanced engine test rig with external boosting system. This approach improved the robustness of the prediction of TDC which will allow engineers to measure accurate combustion data in operating conditions representative of in-service applications.
A Signal Processing of In-Cylinder Pressure for the Resonant Frequency Prediction of Combustion Process in Diesel Engines
Authors: Chen Ximing , Liu Long , Zhang Jiguang , Du Jingtao
Published: January 2019

The combustion resonance is a focal point of the analysis of combustion and thermodynamic processes in diesel engines, such as detecting ‘knock’ and predicting combustion noise. Combustion resonant frequency is also significant for the estimation of in-cylinder bulk gas temperature and trapped mass. Normally, the resonant frequency information is contained in in-cylinder pressure signals. Therefore, the in-cylinder pressure signal processing is used for resonant frequency calculation. Conventional spectral analyses, such as FFT (Fast Fourier transform), are unsuitable for processing in-cylinder pressure signals because of its non-stationary characteristic. Other approaches to deal with non-stationary signals are Short-Time Fourier Transform (STFT) and Continue Wavelet Transform (CWT). However, the choice of size and shape of window for STFT and the selection of wavelet basis for CWT are totally empirical, which is the limit for precisely calculating the resonant frequency. In this study, an approach based on Empirical Wavelet Transform (EWT) and Hilbert Transform (HT) is proposed to process in-cylinder pressure signals and extract resonant frequencies. In order to decompose in-cylinder pressure spectrum precisely, the EWT are applied for separating the frequency band corresponding combustion resonance mode from other irrelevant modes adaptively. The signals containing combustion resonant mode is processed by HT, so that the instantaneous resonant frequency and amplitude can be extracted. Validation is performed by four in-cylinder pressure signals with different injection timing. And the effects of injection timing on resonant frequency are discussed.
Non-Equiprobable Statistical Analysis of Misfires and Partial Burns for Cycle-to-Cycle Control of Combustion Variability
Authors: Maldonado Bryan P. , Stefanopoulou Anna G.
Published: January 2019

Cycle-to-cycle combustion variability (CV) in spark ignition internal combustion engines is amplified at high levels of exhaust gas recirculation (EGR) by sporadic partial burn and misfire events. A non-equiprobable cycle classification method, based on the magnitude of the indicated mean effective pressure (IMEP), was developed to discern and study the deterministic and stochastic components of cyclic CV. The time series analysis of experimental combustion cycles suggested that the occurrence of high energy release cycles right after misfires is the only deterministic component between consecutive cycles. This predictable behavior results from the retained air and fuel from the incomplete combustion cycle to the next. On the other hand, this study shows that the occurrence of partial burn and misfire cycles is the product of the stochastic component of cyclic CV with statistical properties similar to a multinomial probability distribution. It is demonstrated that observation of partial burns can increase the probability of observing a misfire when the conditional probability is used as the metric. Based on these findings, future work will be able to use the observation of partial burns alone to control the upper bound on the probability of misfire events. To this end, different metrics are proposed to control directly and indirectly the probability of misfires, and their advantages and disadvantages for feedback combustion control are discussed.
Analysis of Passenger Car Turbocharged Diesel Engines Performance When Tested at Altitude and of the Altitude Simulator Device Used
Authors: Broatch Alberto , Bermúdez Vicente , Serrano Jose Ramón , Tabet-Aleixandre Roberto , Gómez Javier , Bender Stefan
Published: January 2019

According to current worldwide trends for homologation vehicles in real driving conditions, is forced to test the engines in altitude and in highly dynamic driving cycles in order to approach nowadays and next future emissions standard. Up to now, there were two main options to perform this type of tests: round-robin tests of the whole vehicle or hypobaric chambers, both with high costs and low repeatability.

In this paper a new device is described, which can emulate ambient conditions at whatever altitude between sea level and 5000m high. Even it can be used to emulate ambient conditions at sea level when test bench is placed up to 2000 m high. The main advantages of the altitude simulation equipment are: dynamic emulation of all the psychrometric variables affecting the vehicles during round-robin tests; lower space usage and low energy consumption.

The altitude simulator has been validated comparing with results from a hypobaric chamber at different altitudes. Previously a research about the dispersion in the measurements of both testing devices has been done for assessing the results of the comparison experiment. Final conclusion resulted in the same operating performance and emissions of the studied engine with both types of testing equipments for altitude simulation.
Computational Study of Unsteady Cavitating Flows and Erosion in a Fuel Nozzle
Authors: Hosseinpour Javad , Bravo Luis , Samimi-Abianeh Omid
Published: January 2019

Shear-driven cavitation plays an important role in many technological applications, including fuel injectors and power generators. Cavitation affects the performance of components and hence it is desirable to understand and predict its behavior since it can have favorable as well as adverse consequences. Although there have been a vast number of studies, a full understanding or theoretical framework describing its behavior has not yet been achieved. This is in part due to the complexities associated with cavitating flows including, internal flow physics, turbulence, two-phase flow and non-equilibrium thermodynamics. Further, experimental techniques are limited in their ability to visualize the phenomena with sufficient resolution for a detailed analysis. In this work, an unstructured, finite volume, computational fluid dynamic (CFD) code coupled to the Eulerian-Eulerian multi-fluid model is utilized to study cavitation phenomena in a nozzle. The well-reported Winkhlofer nozzle at a range of conditions including ΔP = 20, 40, 60, 70, 75, 80, and 85 bar is modeled using n-dodecane reference fuel properties. Three cavitation sub-models were investigated and the results compared with previous experimental and simulation flow data. The flow turbulence was modeled using Reynolds Averaged Navier Stokes Equation (RANS) and Large Eddy Simulation (LES) models and the results evaluated. A mesh sensitivity analysis was conducted with minimum cell sizes of 13.40, 9.48, 7.55, and 6.13 μm were considered to show grid convergence. Further, a novel erosion model was also integrated to identify the potential vulnerability damage zones with respect to the nozzle flow operating conditions. The results were in good agreement with experimental data from optical nozzles as well as previous simulation results. The models capture the cavitation near the solid boundary region and were able to predict the critical cavitation as well as the chocked flow regions. This was consistent with all the models. The results from the erosion model revealed a direct relationship between surface erosion, in terms of Mean Depth of Penetration Rate (MDPR) and incubation time, to higher pressure drops across the nozzle. These findings can be useful to develop future injector nozzle designs that can better mitigate cavitation induced material damage for improved engine endurance.
Medium and High Load Performance of Partially Premixed Combustion in a Wave-Piston Multi-Cylinder Engine With Diesel and PRF70 Fuel
Authors: Muric Kenan , Tunestal Per , Magnusson Ingemar
Published: January 2019

European and US emission legislation on diesel compression ignition engines has pushed for the development of new types of combustion concepts to reduce hazardous pollutants and increase fuel efficiency. Partially premixed combustion (PPC) has been proposed as one solution to future restrictions on emissions while providing high gross indicated efficiency. The conceptual idea is that the time for the mixing between fuel and air will be longer when ignition delay is increased by addition of high amounts of exhaust gas recirculation (EGR). Increased air-fuel mixing time will lead to lower soot emissions and the high EGR rates will reduce both NOx emissions and combustion flame temperature, which decreases the overall heat transfer.

Previous research in heavy-duty gasoline PPC has mostly focused on emissions and efficiency at low and medium load in single-cylinder engines. In this paper a Volvo D13 heavy-duty single-stage VGT engine with a newly developed Wave piston was run at medium and high engine load with a variation in fuel injection pressure. The Wave piston was specifically designed to enhance air-fuel mixing and increase combustion velocity. Two fuels were used in the experiments, PRF70 and Swedish MK1 diesel. Soot-NOx trade-off, combustion characteristics and efficiency were compared for both fuels at 1000 and 2000 Nm engine torque. The results show that at high load the combustion behavior with respect to rate of heat release and heat transfer is very similar between the fuels and no major difference in indicated efficiency could be observed. Peak gross indicated efficiencies were reported to be around 49 % for both fuels at 1000 Nm and slightly above 50 % at 2000 Nm. The new Wave piston made it possible to obtain 1 g/kWh engine-out NOx emissions while still complying with Euro VI legislation for particulate emissions. Soot emissions were generally lower for PRF70 compared to MK1 diesel. We could also conclude that gas exchange performance is a major issue when running high load PPC where high Λ and EGR is required. The single-stage VGT turbocharger could not provide sufficient boost to keep Λ above 1.3 at high EGR rates. This penalized combustion efficiency and soot emissions when reaching Euro VI NOx emission levels (0.3–0.5 g/kWh).
Initial Results on a New Light-Duty 2.7L Opposed-Piston Gasoline Compression Ignition Multi-Cylinder Engine
Authors: Salvi Ashwin , Hanson Reed , Zermeno Rodrigo , Regner Gerhard , Sellnau Mark , Redon Fabien
Published: January 2019

Gasoline compression ignition (GCI) is a cost-effective approach to achieving diesel-like efficiencies with low emissions. Traditional challenges with GCI arise at low-load conditions due to low charge temperatures causing combustion instability and at high-load conditions due to peak cylinder pressure and noise limitations. The fundamental architecture of the two-stroke Achates Power Opposed-Piston Engine (OP Engine) enables GCI by decoupling piston motion from cylinder scavenging, allowing for flexible and independent control of cylinder residual fraction and temperature leading to improved low load combustion. In addition, the high peak cylinder pressure and noise challenges at high-load operation are mitigated by the lower BMEP operation and faster heat release for the same pressure rise rate of the OP Engine. These advantages further solidify the performance benefits of the OP Engine and demonstrate the near-term feasibility of advanced combustion technologies, enabled by the opposed-piston architecture.

This paper presents initial results from a steady state testing on a brand new 2.7L OP GCI multi-cylinder engine. A part of the recipe for successful GCI operation calls for high compression ratio, leading to higher combustion stability at low-loads, higher efficiencies, and lower cycle HC+NOx emissions. In addition, initial results on catalyst light-off mode with GCI are also presented. The OP Engine’s architectural advantages enable faster and earlier catalyst light-off while producing low emissions, which further improves cycle emissions and fuel consumption over conventional engines.
Performance and Combustion Investigation of a Lean Burn Natural Gas Engine Using CFD
Authors: Sahoo Sridhar , Tripathy Srinibas , Srivastava Dhananjay Kumar
Published: January 2019

Natural gas is widely used in sequentially port fuel injection engine to meet stringent emission regulation. Lean burn operation is one of the ways to improve spark-ignition engine fuel economy. The instability in the combustion process of the lean burn engine is one of the major challenges for engine research. In this study, the performance and combustion characteristics of a lean burn sequential injection compressed natural gas (CNG) engine were investigated numerically using computational fluid dynamics (CFD) modeling over a wide range of air/fuel equivalence ratio. A detailed chemical kinetic mechanism was used for natural gas combustion along with laminar flame speed model to capture lean burn operating condition within the combustion chamber. Combustion pressure, indicated mean effective pressure (IMEP), and heat release were analyzed for performance analysis, whereas flame development angle (CA 10), combustion duration, thermal efficiency were taken for combustion analysis. The results show that on increasing air/fuel equivalence ratio at a given spark timing, IMEP decreases as the lean burn mixture produces less amount of gross power output due to insufficient available energy. Moreover, lower burning velocity characteristic of natural gas extends the combustion duration, where a substantial amount of total energy released after top dead center. It is also seen that optimum spark timing (MBT) for maximum IMEP advances with an increase in air/fuel equivalence ratio due to late ignition timing under lean burn condition. CFD model successfully captures the effect of dilution to illustrate the considerations to design future combustion engine for spark ignited natural gas engine.
Numerical Study on Fretting Wear of Mating Surface Between Piston Crown and Skirt in Heavy Duty Diesel Engine
Authors: Wang Yi , Wu Limin , Liu Shuo , Li Mei , Meng Xianghui , Cui Yi
Published: January 2019

Composite pistons are often used in heavy duty diesel engines due to its good reliability and durability. Owing to the alternating loads, fretting wear usually happens on the mating surfaces between piston crown and skirt. In this paper, a fretting wear finite element model is developed to analyze the mating surface wear of composite piston of heavy duty diesel engine. The fretting wear model predicts the wear depth evolution for each working cycle based on Archard model and mesh updating technique, which is validated by previous pin and disk contact experiments. The wear evolution of the top contact surface of piston skirt is simulated according to engine operating condition, and fretting wear life is estimated by the decreasing process of crown-skirt connecting bolt preload. Effects of the shape of piston skirt top surface is also evaluated. In the end, the rationality of fretting wear model is validated by durability tests of diesel engine.
Emission and Combustion Characteristics of Diesel Engine Fumigated With Ammonia
Authors: Niki Yoichi , Nitta Yoshifuru , Sekiguchi Hidenori , Hirata Koichi
Published: January 2019

It is well known that ammonia (NH3) combustion does not produce carbon dioxide (CO2) causing global warming. Therefore, NH3 has received much attention as an alternative diesel fuel for internal combustion engines. On the other hand, it has been reported that the exhaust gas of diesel engine fumigated with NH3 contains unburned NH3 with toxicity for humans and nitrous oxide (N2O) with strong global warming effect. Hence the NH3 and N2O emissions should be reduced to prevent the human health damage and global warming.

The aim of this study was to develop the combustion strategies for reducing the unburned NH3 and N2O emissions on diesel engine fumigated with NH3. The experimental results indicated that the higher temperature combustion of NH3 prevents the N2O production and allows itself to react well. From the numerical simulation results, hydrocarbon combustion decomposes NH3 and N2O in ignition processes.
Investigation of the Impact of Adding Titanium Dioxide to Jojoba Biodiesel-Diesel-N-Hexane Mixture on the Performance and Emission Characteristics of a Diesel Engine
Authors: El-Seesy Ahmed I. , Hassan Hamdy , Dawood Alaa , Attia Ali M. A. , Kosaka Hidenori , Ookawara Shinichi
Published: January 2019

In this experimental examination, an attempt was made to improve the performance and diminish the exhaust emissions by adding titanium oxide (TiO2) nanoparticles into J30D5H blend (5% by volume n-hexane, 30% by volume jojoba methyl ester, and 65% by volume diesel fuel) under various engine loads and a constant speed of 2000 rpm. The titanium oxide nanoparticles were added to J30D5H blend at two proportions, including 25 mg/l and 50 mg/l by using an ultrasonic technique. The addition of TiO2 into J30D5H led to a significant improvement in the engine performance, where the brake specific fuel consumption was reduced by 12%, while the brake thermal efficiency was increased by 15% compared to J30D5H blend. The combustion consequences for the J30D5H blend with nanoparticles addition exhibited that the peak pressure and maximum heat release rate were increased by approximately 4.5% and 2%, respectively. Moreover, the CO and UHC emissions were reduced by 20% and 50%, respectively. Nevertheless, the NOx emission was increased by about 15% with adding TiO2 into J30D5H blend.
Coordinated Control Strategy in Engine Starting Process for a Novel Compound Power-Split Hybrid Electric Vehicle
Authors: Shen Dengfeng , Gühmann Clemens , Zhang Tong , Dong Xizhen
Published: January 2019

Due to the direct connection between the engine and the compound power split hybrid transmission (CPSHT) in hybrid electric vehicle (HEV), engine ripple torque (ERT) can result in obvious jerks in engine starting process (ESP). In order to improve the riding comfort, two wet clutches are mounted in this novel CPSHT. This research developed a new coordinated control strategy and its effectiveness was verified in simulation. Firstly, the mechanical and hydraulic parts of the CPSHT were introduced, and the riding comfort problem during ESP in primary design was illustrated. Secondly, the dynamic plant model including ERT, driveline model and clutch torque was deduced. Thirdly, a coordinated control strategy was designed to determine the target engine torque, motor torque, clutch torque and the moment of fuel injection. A Kalman filter based clutch torque estimator was applied with the help of electric motors information. The simulation result indicates that proposed coordinated control strategy can indeed suppress vehicle jerk and improve the riding comfort in ESP.
Spray Evaporative Cooling System Design for Automotive Internal Combustion Engines
Authors: T. Jose Jisjoe , Dunne Julian F. , Pirault Jean-Pierre , Long Christopher A.
Published: January 2019

IC engine spray evaporative cooling system design is discussed starting with a review of existing evaporative cooling systems that automotive applications are required to address. A component-level system design is proposed culminating in a simulation model of a PID strategy used to control transient gasside metal temperatures with varying engine load. The model combines a spray evaporation correlation model with 1D finite-difference equations to model the transient heat transfer through a 7 mm thick metal slab which represents the wall of a cylinderhead. Based on the simulation results, the particular changes required of existing engine cooling jacket designs are discussed.
Comparison of Near-Wall Flow and Heat Transfer of an Internal Combustion Engine Using Particle Image Velocimetry and Computational Fluid Dynamics
Authors: Wu Angela , Keum Seunghwan , Greene Mark , Reuss David , Sick Volker
Published: January 2019

In this study, CFD modeling capability of near-wall flow and heat transfer was evaluated against experimental data. Industry-standard wall models for RANS and LES (law of the wall) were examined against near-wall flow and heat flux measurements from the transparent combustion chamber (TCC-III) engine. The study shows that the measured, normalized velocity profile does not follow law of the wall. This wall model, which provides boundary conditions for the simulations, failed to predict the measured velocity profiles away from the wall. LES showed reasonable prediction in peak heat flux and peak in-cylinder pressure to the experiment, while RANS-heat flux was closer to experimental heat flux but lower in peak pressure. The measurement resolution is higher than that of the simulations, indicating that higher spatial resolution for CFD is needed near the wall to accurately represent the flow and heat transfer. Near-wall mesh refinement was then performed in LES. The wall-normal velocity from the refined mesh case matches better with measurements compared to the wall-parallel velocity. Mesh refinement leads to a normalized velocity profile that matches with measurement in trend only. In addition, the heat flux and its peak value matches well with the experimental heat flux compared to the base mesh.
Development of a Hybrid Lagrangian-Eulerian Model to Describe Spark-Ignition Processes at Engine-Like Turbulent Flow Conditions
Authors: Scarcelli Riccardo , Zhang Anqi , Wallner Thomas , Som Sibendu , Huang Jing , Wijeyakulasuriya Sameera , Mao Yijin , Zhu Xiucheng , Lee Seong-Young
Published: January 2019

With the engine technology moving towards more challenging (highly dilute and boosted) operation, spark-ignition processes play a key role in determining flame propagation and completeness of the combustion process. On the computational side, there is plenty of spark-ignition models available in literature and validated under conventional, stoichiometric SI operation. Nevertheless, these models need to be expanded and developed on more physical grounds since at challenging operation they are not truly predictive.

This paper reports on the development of a dedicated model for the spark-ignition event at non-quiescent, engine-like conditions, performed in the commercial CFD code CONVERGE. The developed methodology leverages previous findings that have expanded the use and improved the accuracy of Eulerian-type energy deposition models. In this work, the Eulerian energy deposition is coupled at every computational time-step with a Lagrangian-type evolution of the spark channel. Typical features such as spark channel elongation, stretch, attachment to the electrodes are properly described to deliver realistic energy deposition along the channel during the entire ignition process.

The numerical results are validated against schlieren images from an optical constant volume chamber and show the improvement in the simulation of the spark channel during the entire ignition event, with respect to the most commonly used energy deposition approach. Further development pathways are discussed to provide more physics-based features from the developed ignition model in the future.